EP1529573A1

EP1529573A1 - A plant for bending metal bars, with automatic transfer of the bars into the bending position

Info

Publication number: EP1529573A1
Application number: EP04026138A
Authority: EP
Inventors: Stefano Peruzzo
Original assignee: Oscam SpA
Current assignee: Oscam SpA
Priority date: 2003-11-07
Filing date: 2004-11-04
Publication date: 2005-05-11
Anticipated expiration: 2024-11-04
Also published as: ES2312902T3; ATE406223T1; DE602004016103D1; EP1529573B1; ITTO20040203A1; IT1351915B1

Abstract

A plant (1) for bending metal bars (B) envisages a stationary structure (11) adjacent to the bending units (2), provided on which are a number of sets of mobile transverse arms (13,14,15), which are controlled for picking up the bars (B) from the stationary structure (11) and unloading them automatically as far as within the receiving space (8) provided on said bending units (2).

Description

The present invention relates to the field of plants for bending metal bars, in particular bars for the reinforcement of concrete.
Known in general are plants of the type specified above, which comprise:

a stationary structure having at least one supporting surface for receiving the bars arranged substantially parallel to one another; and
at least one bending unit, which is set adjacent to the stationary structure and defines a surface for bending the bars and a space for receiving one or more bars to be bent on the bending unit or units, said bars being arranged usually parallel to one another and aligned in a plane substantially orthogonal to the bending surface.

In known plants, the bars to be bent are transferred onto one or more bending units after they have been picked up from a station, in which they are arranged substantially parallel to one another even though sometimes they criss-cross one another. Transfer occurs typically by translating the bars in a direction transverse to their longitudinal direction of lie and possibly in the vertical direction. In a case provided by way of example, the pick-up station is constituted by a channel provided on a bench, where the bars are cut to the desired length starting from bars of a pre-set standard length, but can be constituted also by transfer tracks, storage areas, catenaries, or areas specifically dedicated to feeding the bending units.
In more traditional solutions, transfer of the bars onto the bending unit is carried out manually by one or more operators. For example, known to the art are machines of the latter more conventional type, in which the pick-up station is provided with a set of lifting arms extending in a transverse direction underneath the bars received on the pick-up station, which is rack-shaped. Said arms are able to be raised above the surface for resting the bars, passing through the spaces defined between the various elements of the rack so as to bring the bars to a level where they can be easily picked up manually by the operators. Alternatively, lever loading systems are used, in which the operators transfer the bars manually to a pre-loading station, from which the levers pick said bars up, but in which the levers are carried by the bending units so that, above all on account of the excessive distance between the levers, in the case of long bars, problems of criss-crossing or deflection arise, and often a further manual intervention is necessary prior to proceeding to the bending operation. Consequently, at best some reduction of the physical fatigue of the operators may be achieved, but a really automatic apparatus is not obtained.
Alternatively, there are also systems (JP 2002 143931) in which the bars are simply brought up to the bending surface, without however their being introduced into the receiving space in which they will undergo bending, said systems merely being aimed at reducing the muscular effort of the operator. None of the above systems performs the loading cycle in an automatic and reliable way.
The present applicant has also proposed in the past various types of automatic devices for handling bars inside the bending plant. For example, the European patent No. EP648577B1, filed in the name of the present applicant, proposes equipping the bending units with mobile pick-up structures capable of picking up the bars from seats, in which they are stacked on top of one another vertically, and transferring them onto the bending units. The present applicant has also proposed a device for handling bars that employs grippers, which forms the subject of the European patent application No. 03014748, still secret at the date of filing of the present patent application.
The purpose of the present invention is a device of an improved type for transferring bars, which will be able to transfer the bars into the receiving space defined on one or more bending units with which the plant is equipped, with means that are relatively simple, functional, and inexpensive.
With a view to achieving the aforesaid purpose, the subject of the invention is a plant which presents all the characteristics indicated at the beginning of the present description and is further characterized in that:

it comprises means for transferring one or more bars from the stationary structure onto said at least one bending unit;
said transfer means comprise a plurality of first arms or levers, which are substantially parallel to one another and are set in a transverse direction with respect to the longitudinal direction of lie of the bars on the stationary structure;
said arms are mounted on the stationary structure, and distributed in the longitudinal direction of lie of the bars; and
means are provided for controlling a simultaneous movement of said arms or levers from a first position, in which they are designed to receive the bars from said supporting surface on the stationary structure, to a second position for unloading the bars into said receiving space on said bending unit.

It should be emphasized that the set of the aforesaid first arms or levers is carried by the stationary structure of the plant and is able to form an inclined plane, which is not necessarily rectilinear, but could even be curved when the arms are arranged in the aforesaid second position and from which the bars are unloaded onto the receiving space on the bending unit or units.
In a preferred embodiment, the surface of the aforesaid first arms or levers has a cradle-shaped concave curved profile. Thanks to said characteristic, when the arms are gradually brought up to their second position for unloading the bars onto the bending units, the bars at no point follow stretches with a very marked inclination and, in the final stage, they encounter a decreasing inclination, so that they are slowed down in their travel prior to arrival in the receiving space on the bending unit. Said characteristic constitutes an important advantage in so far as it prevents the bars from arriving in the receiving space higgledy-piggledy, criss-crossing one another, or in any case at an excessive rate. At the same time, the cradle-shaped concave profile of the arms is such that, even in the case where the bars arrive on the arms in a condition in which they criss-cross one another, are entangled, or are on top of one another, they tend to arrange themselves in a coplanar condition following their natural oscillations on the cradle-shaped surface. This guarantees that, in the final stage, the bars will enter the receiving space on the bending unit one after another, thus lying on top of one another in the aforesaid plane orthogonal to the bending surface in the same order on all the bending units.
Furthermore, in a particularly preferred case in which there are two bending units both of which are mobile with respect to one another, a vice is set for keeping the bars stationary during the bending operations. Also this vice is provided with a receiving space similar to that of the bending units. Consequently, it is important that also therein the bars enter in an orderly way and in the same order in which they entered the receiving spaces of the bending units, and the plant forming the subject of the invention enables this to be achieved. This vice may be fixed or even mobile in the longitudinal direction of the bars in order to enable unloading of the finished product throughout the length of the plant. In general, it is also possible to have vices also set on the at least one bending unit even in the case where a different number of mobile or fixed bending units is envisaged.
In a particular embodiment, illustrated in what follows, the aforesaid curved profile of each of the aforesaid first arms has one end facing the bending unit, where an arrest surface for the bars is defined. In addition, in the preferred embodiment, the transfer means comprise a plurality of second arms or levers also mounted on the stationary structure and distributed in the longitudinal direction of lie of the bars on the stationary structure in positions interspersed with those of the first arms. Said second arms are designed to co-operate with the first arms to receive the bars carried by the first arms after the latter have been brought into their second position. In said condition, the bars initially arranged on the first arms move downwards, rolling thereon, until they come to stop against the arrest surfaces at the ends of the first arms. The second arms are arranged to form an inclined surface adjacent to the surface defined by the first arms in such a way that a subsequent further slight lowering of the first arms causes the bars to be received on the second arms, albeit remaining stationary against said arrest surfaces of the first arms, which in said step still project over the second arms. A further lowering of the first arms hence causes the bars to slide by gravity on the inclined plane defined by the second arms until they enter, one after another, the receiving space on the bending units. Consequently, in the preferred embodiment, the final stage of sliding of the bars takes place on the inclined plane defined by the aforesaid second arms, which possibly co-operate also with other structures, such as inclined planes carried by the bending units, but starting from a position close to the receiving space so that the bars are not able to acquire an excessive speed, which could jeopardize orderly and correct transfer into the receiving space.
According to yet a further characteristic, the transfer means finally comprise a plurality of third arms or levers mounted once again on the stationary structure and distributed in the longitudinal direction of lie of the bars on the stationary structure, in positions interspersed with those of the first arms and of the second arms. Said third arms or levers are able to move simultaneously between a first position substantially underneath the surface for supporting the bars on the stationary structure and a second position substantially above said surface, in such a way that raising of said third arms or levers from the first position to the second position brings about interception of the bars which are located on said supporting surface and their transfer onto the first arms or levers.
Once again according to a further preferred characteristic, the first arms, second arms and third arms are mounted articulated to the stationary structure about a common axis, so that their movement between the respective operative positions is a movement of rotation about said axis.
In the case of a concrete embodiment, each set of arms constitutes a single rack structure, which is set in motion by motor means of any type, for example by fluid-driven cylinders.
Once again according to a further preferred characteristic of the invention, associated to the stationary structure are also fourth arms or levers, which are also distributed in the longitudinal direction of lie of the bars and can be raised from a first position to a second position for intercepting the bars that are located on the supporting surface on the stationary structure and cause them to slide towards an unloading position designed for receiving the bars that do not require bending operations. In this way, should the supporting surface on the stationary structure receive bars that are not to be bent, the first, second and third arms do not intervene and the aforesaid fourth arms unload said bars, bypassing the bending units, typically unloading them on the side opposite to the one in which there is located the at least one bending unit with respect to the longitudinal axis of the bars. In order to maximize the productivity of the apparatus and reduce dead times, it is possible to provide control means such that, according to the duration of the cycles for cutting and bending or for cutting only, will appropriately alternate cycles for cutting only and for bending only. The bars that have only been cut will be unloaded preferably on the opposite side to that of the at least one bending unit, but sometimes even on the same side in the case of particular requirements.
In a preferred embodiment, means are provided designed to cause, by appropriately arranging the bending units according to the position of the bars, the position of dropping of the bars and, in particular, the length of the trailing portion of each bar which projects longitudinally outside the receiving space ???(8) on the bending units to be a function of the diameter of the bars, of their length, of their mechanical characteristics and possibly of their number so as to reduce the risk of criss-crossing.
In a normal cycle of transfer of bars that are to undergo bending, the aforesaid third arms intercept the bars that have arrived on the supporting surface on the stationary structure (in a typical case, the bottom of a channel provided on the bench where the bars are cut to the desired length, but even the pre-loading area of a bending plant or the like) and transfer them onto the first arms. The latter are displaced downwards, in the meantime leaving the bars free to set themselves in order in a condition in which they are set alongside one another along the surface of the curve that constitutes the profile of the cradles, without any criss-crossing, and stop the bars in said condition at a short distance from the receiving space on the bending units. This is obtained on account of the fact that the first arms move into their lowered position, in which the bars slide thereon, stopping on top of the arrest surfaces defined at the ends of the first arms. Starting from said condition, the first arms are further lowered, so as to enable the second arms, set adjacent thereto, to receive the bars and finally guide them as they drop into the receiving space on the bending units, once the arrest surfaces at the ends of the first arms drop below the second arms. While the first and second arms are operating in this way, the third arms can return into their starting position so as to be ready to receive a new set of bars present in the channel of the cutting bench, without waiting for the other arms to complete their cycle, so as to eliminate any dead time.
It should be noted that the plant according to the invention enables automatic unloading of the bars into a receiving space, which is the one in which the bars are located during the bending operations, so that, unlike other plants, no further transfer of the bars to be carried out either manually or via additional devices is necessary.
The plant according to the invention is hence characterized by a high operating efficiency and, at the same time, has an extremely simple and reliable structure.
Further characteristics and advantages of the invention will emerge from the ensuing description with reference to the annexed plate of drawings, which are provided purely by way of non-limiting example and in which:

Figure 1 is a partial schematic plan view of a plant according to one example of embodiment of the present invention;
Figures 2 and 2A are plan views, at an enlarged scale, of two bending units forming part of the plant of Figure 1, before and after the bending operation;
Figure 3 is a partially cross-sectional side view of the plant in a first condition of operation;
Figures 4-10 are views corresponding to that of Figure 3 which illustrate the plant in various conditions of operation;
Figures 11 and 12 are views similar to that of Figure 3, which illustrate a plant made according to a variant of the invention, in conditions of operation substantially corresponding to the ones illustrated in Figures 6 and 8; and
Figure 13 is a schematic view illustrating the principle underlying the variant of Figures 11 and 12.

In the plate of drawings, the reference number 1 designates, as a whole, a plant according to the invention. Said plant comprises, with reference to the specific example illustrated, two bending units 2 (see Figure 2), each of which can be made in any known way. Once again with reference to the example illustrated schematically in the plate of drawings, each bending unit 2 comprises a supporting structure 3, on which there is mounted so that it can turn a bending disk 4, which has a central spindle 5 and carries an eccentric pin 6 for bending a portion of one or more bars B around the central spindle 5. In the specific example illustrated, the axis 4A (Figure 3) of the bending disk 4 is inclined with respect to the vertical direction. However, it would also be possible for said axis to be oriented vertically, as is also well known to the art. With reference once again to Figure 2, during bending of the bar B, the portion thereof adjacent to the part that is bent comes to rest against a contrast element 7, carried by the structure 3 of the machine, which is illustrated in a purely schematic way in Figure 2. This contrast could possibly carry an inclined chute co-operating with the second arms in the final unloading step.
The annexed plate of drawings does not show the structure inside the outer casing of the machine, which comprises the motor means for rotation of the disk 4, as well as the means possibly provided for bringing about lowering of the disk below the top surface of the machine to perform bends in the second direction of rotation of the disk.
As may be seen in Figures 3 and 4, the two bending units 2 define a receiving space 8 for the bars to be bent, in which a number of bars can be received set on top of one another in a plane substantially orthogonal to the bending plane of the bars.
Figure 9 of the annexed plate of drawings shows, for example, three bars B designed to undergo bending operations, which are received in the receiving space 8 of the bending units.
Once again with reference to Figure 2, in the case of the example illustrated, the two bending units 2 are mobile on rails 9 in the direction A parallel to the longitudinal direction of lie of the bars B. Typically, once again according to a technique in itself known, provided inside the casing 3 of each bending unit are motor means designed to control movement of the bending unit along the rails 9. Furthermore, the plant is provided with an electronic control system, which controls, according to a pre-set program, the subsequent movements of the bending units 2 and of the corresponding bending disks to carry out the various bends on a bar or on a set of bars subjected simultaneously to bending in order to obtain any pre-set shape.
The bending units 2 may be of the type illustrated in Figures 2 and 2A, with a spindle 5, around which the bars are bent, and with the contrast element 7, or else they may be of the type with a spindle having a diametral slit, which also defines the receiving space for the bars. In this case, one of the portions will possibly function also as contrast element.
Once again according to a technique in itself known, the two bending units 2 of the plant according to the invention are arranged, in the case of the specific example illustrated, adjacent to a bench, on which the bars that are to undergo bending are cut to the desired length, starting from bars of a standard length. Said bench, designated as a whole by the reference number 10 (see Figures 1 and 3), comprises a stationary structure 11, on which there is a channel 12, along the bottom of which the bars B are fed, possibly after they have undergone a cutting operation. In the present description, and in the annexed plate of drawings, the details corresponding to the device for carrying out cutting of the bars and to the device for feeding the bars longitudinally to the cutting device are not shown. Not shown either are the possible devices for arrest of the bars, up against which the ends of the bars are set to enable regulation of the cutting length prior to the cutting operation. All the aforesaid constructional details regard the conventional technique of benches for cutting metal bars, which, of course, do not fall within the scope of the present invention. In any case, purely by way of reference, it is emphasized herein that the bars arrive in the channel 12 by being fed in the direction of their length on a roller surface 130. It should be noted that the channel 12 has interruptions along its length, which, on the one hand, do not prevent the bars from resting in a secure way on said plane and, on the other hand, enable passage through the spaces thus defined of the elements forming part of the device according to the invention that will be described in what follows.
In accordance with a preceding patent application filed in the name of the present applicant, the stationary structure is preferably provided with a plurality of resting surfaces that can be sent down (not illustrated), set adjacent to one another, which can be selectively brought into their operative raised position to provide a continuous resting surface for the bars B at least for a substantial part of the space comprised between the two bending units 2, however the latter may be positioned, said resting surface being preferably coplanar with the top surfaces of the bending units 2 in such a way that the bars B do not bend or deform as a result of gravity. In their lowered inoperative position, instead, the resting surfaces do not interfere with the movement of the bending units 2 in the direction A. On a part of some of these resting surfaces there could also be mounted hide-away surfaces forming inclined planes, said surfaces being coplanar, at least for one stretch, with said second arms 14, when the latter are in their lowered position, and with said elements 7. Once the loading step has been completed, these inclined surfaces would disappear leaving a plane table during the bending cycle. In order to reduce further deformation and bending of the bars due to gravity it would be possible to add to the inclined surface a receiving space 8 proper, so increasing the points on which the bars B rest.
Alternatively, a roller-shutter-type hide-away structure could be used like the one described in the European patent EP1184099 filed in the name of the present applicant or, at least, an additional resting surface for the at least one bending unit 2.
With reference now to the device according to the invention, the preferred embodiment illustrated herein envisages four sets of arms 13, 14, 15 and 16 used for movement of the bars, said arms being mounted in an articulated way on the stationary structure 11 of the bench 10. According to the invention, one first set of arms 13 is mounted articulated on the stationary structure 11 about an axis A parallel to the longitudinal direction of lie of the bars B in the channel 12. The arms 13 extend in a transverse direction with respect to the longitudinal direction of the bars and are distributed along said length, i.e., along the axis A on the bench 10. They are moreover connected to one another by a longitudinal structure 13A (Figure 1) so that they are able to move simultaneously about the respective axis of articulation A. The movement of the structure comprising the set of the arms 13 is controlled by means of one or more fluid-driven cylinders 17, each of which has an end articulated to the stationary structure 11 and a stem, the opposite end of which is connected, in an articulated way, to the structure comprising the arms 13.
Figure 3 illustrates the arms 13 in a raised position, in which they are set for receiving a set of bars B to be transferred onto the bending unit 2. The set of arms 15 (also visible in the plate of drawings) comprises a plurality of arms, which are also articulated around the aforesaid longitudinal axis A and also extend in a direction transverse to said axis, on the opposite side with respect to the arms 13. Also in the case of the arms 15, these are connected by a transverse structure (not visible in the plate of drawings), which is such that said arms can move simultaneously rotating all about the aforesaid axis A. Said movement is controlled by one or more fluid-driven cylinders 18, each of which has one end articulated to the stationary structure 11 and a stem, the free end of which is connected in an articulated way to the arm structure comprising the arms 15. Figure 3 shows the arms 15 in a lowered starting condition, in which said arms are set underneath the bottom of the channel 12 in which the bars B are received.
Once again with reference to the plate of drawings, the device comprises a further set of arms 14 set in a direction transverse to the longitudinal direction of lie of the bars and articulated about the same axis A of articulation of the arms 13 and 15. Also the arms 14 are distributed along the bench 10 and are each adjacent to a respective arm 13. Also the arms 14 are connected to one another by means of a longitudinal structure 14A (Figure 1).
Finally, once again in the case of the specific example illustrated, the plant comprises a further set of transverse arms 16, which are connected to one another by a structure 16A, are distributed along the bench 10, are also set in the resting position underneath the plane of the cutting channel 12, and are articulated about a longitudinal axis C located on one side of the bench 10 opposite to the one having the axis A (Figures 1 and 3).
A further important characteristic of the device according to the invention lies in the fact that the top surface of each transverse arm 13 has a cradle-shaped concave profile 13B (Figure 3). Thanks to said characteristic, the surface defined by the set of the arms 13 is a cradle-shaped surface, the generatrices of which are parallel to the axis A and the function of which will emerge clearly from what follows.
Finally, a further characteristic of the plant according to the invention, in the case of the specific example illustrated here, lies in the fact that the central spindle 5 of the bending disks 4 has a top prolongation 5A functioning as arrest for the bars which are to be made to drop into the receiving space 8 described above.
Operation of the plant according to the invention is described in what follows.
In the starting condition, the arms 13, 14, 15 and 16 are in the positions illustrated in Figure 3. In said condition, it is assumed that the cutting channel 12, or in any case the pick-up station, will receive a plurality of bars B designed to undergo a bending operation of the same type as the one illustrated in Figure 2A. The device according to the invention is used for transferring the bars from the cutting channel 12 to the receiving space 8 on the bending units. In a first step (Figure 4), the cylinder, or cylinders, 18 which control the position of the arms 15 are actuated for controlling simultaneous displacement of said arms from the lowered position illustrated in Figure 3 to the raised position illustrated in Figure 4. Following upon said movement, the arms 15 intercept the bars B that are located in the cutting channel 12, causing transfer thereof onto the arms 13. As may be seen in Figure 4, the arrangement of the arms 15 and 13 and their conformation are such that, when the arms 15 are raised, their top surfaces define an inclined plane flush with the surface defined by the top edges of the arms 13. In this way, the bars B are forced to slide downwards, gathering on the surface 13B of the arm 13. In said step, the cradle-shaped concave profile of the top surface defined by the arms 13 can bring about a certain movement of oscillation of the bars B, which helps to eliminate any possible criss-crossing of the bars and to arrange the latter substantially alongside one another along the curve that defines the profile of the surface 13B.
Figure 5 shows how the arms 15, once the bars B have been transferred onto the arms 13, can return immediately into the starting position, in which they are ready to pick up a new set of bars B received in the cutting channel 12.
As is illustrated in Figure 6, at the same time or even beforehand or immediately afterwards, the arms 14 can be brought into their lowered position, in which their top edges define an inclined plane that is aligned with the top inclined surface of the contrast elements 7 of the bending units, so that they can co-operate therewith for unloading the bars B directly into the receiving space 8. In any case, the top surface of the contrast elements 7 can have different inclinations in the various stretches, for example a decreasing inclination (whether with a continuous curve or with broken-line stretches with different inclinations), and a chamfered edge for facilitating introduction into the final stretch, and alignment with the arms 14 can occur even just for an appropriate stretch. Furthermore, in a preferred embodiment, additional structures provided with a profile defining an inclined plane aligned for an appropriate stretch with the arms 14 can be set on hide-away structures located between the bending units 2, such as, for example, the aforementioned send-down resting surfaces, in such a way as to facilitate an orderly movement of the bars in the final stretch of transfer.
Once the arms 14 have been set in the condition illustrated in Figure 6 or whilst they are terminating said movement, also the arms 13 are lowered. Of course, in order to lower the arms 13 or 14, it is necessary for the bending units not to be moving or set in points in which structures that said units carry, in particular the contrast elements 7, can interfere with the aforesaid arms. As may be seen in the plate of drawings, in the example illustrated, each arm has, at its free end, an arrest finger 13C, which projects upwards and defines an arrest surface for the bars B arranged on the arms 13. When the arms 13 are lowered towards the position illustrated in Figure 7, the bars are initially forced to slide downwards. Said sliding movement, however, is slowed down by the cradle-shaped conformation of the top profiles of the arms 13, said conformation hence performing, also thanks to the movement of oscillation induced in the bars B, the function of preventing any criss-crossing between the bars B and of preventing the bars in their travel from reaching an excessive speed. Shortly before reaching the final position illustrated in Figure 7, the bars B are thus all set alongside one another on the arms 13 but stopped against the arrest fingers 13C. Once the position illustrated in Figure 7 is reached, the arms 13 have their top edges set below the top edges of the arms 14, so that the bars B are taken up by the arms ,14. However, the position reached by the arms 13 is such that the arrest fingers 13C are still able to keep the bars B stationary against them and set alongside one another. Consequently, in the condition illustrated in Figure 7, the result is achieved of arranging the set of bars B on the inclined plane defined by the top edges of the arms 14, keeping them temporarily stationary, at a short distance from the receiving spaces 8 on the bending units. Said result is a further advantage, which guarantees reliability of operation of the device in obtaining a correct and orderly introduction of the bars into the receiving spaces 8. Of course, it could even be possible for the arrest fingers 13C not to be carried by the lever arms, but by the contrast elements 7 or else by the bending units 2. In any case, said arrest fingers will have to be provided with means, for example motors or fluid-driven cylinders, such as to enable them to be brought into a position in which there is no interference with the bars B, leaving the latter free to drop into the receiving space 8. Furthermore, it could be envisaged that the distance of the arrest fingers 13C and/or of the ends of the lever arms 13 and/or 14 from the receiving space 8 will be adjustable.
Figure 8 shows the immediately subsequent step, in which the arms 13 are further lowered, so as to remove the arrest fingers 13C from any possible interference with the bars B and consequently leave the latter free to move by gravity (and/or by inertia, in the case where the arrest fingers 13C are not present) one after another until they enter the receiving space 8 after they have possibly struck against the arrest surface 5 and 5A. In this way, the bars reach the condition illustrated in Figure 9, where they are set on top of one another in a plane substantially orthogonal to the bending plane of the bars. Once said condition has been reached, the arms 13 and 14 can be brought back again into their starting positions, illustrated in Figure 3, and the bending unit can be controlled according to any programmed bending cycle, to perform the bending operation as illustrated in Figures 2 and 2A. Before the start of the bending cycle, it may be possible to set the bars B head on, for example by pushing them via an arrest element carried by a mobile bending unit in the direction A. Alternatively, the bending units will be displaced in the case where the position of start of bending does not coincide with that of loading of the bars B in so far as it has been necessary to prevent interference between the arms or levers 13 and 14 and the bending units 2 with all the items that they carry.
Figure 10 illustrates once again the case where there arrive, in the cutting channel 12, bars B that are not to undergo any bending operation. In this case, the bars are intercepted by the arms 16, which are raised to enable the bars B to slide on the side of the bench 10 opposite to that of the bending unit 2.
As regards the bars which have to undergo bending, once the bending operation is completed, said bars can be unloaded, on the right (with reference to Figures 3 and 10) of the bending units, onto any suitable receiving device, such as a rack, a bench, a trolley, an endless belt, or in general any storage or conveying device.
There will frequently arise the case where a mobile magazine will be used such as to translate partially underneath the plant so as to be able to gather together in the various unloading positions various metal bars or rods that are to be grouped together.
Transfer of the bars from the bending units onto the unloading station can be obtained in any known way, including the use of gripper means for automatic movement, such as the ones that form the subject of the prior European patent application No. 03014748 filed in the name of the present applicant, or lever expellers.
As emerges clearly from the foregoing description, the system according to the invention is characterized, on the one hand, by a considerable simplicity and consequently by a low cost of fabrication and, on the other hand, by a high reliability and efficiency of operation. A fundamental characteristic of the invention lies in the fact that the arms or levers used for handling the bars are all carried by the stationary structure adjacent to the bending units and are able to handle the bars by picking them up from a horizontal coplanar condition, or in any case a condition of alignment on a plane with moderate inclination, and unloading them into the receiving space 8 on the bending units without any manual intervention, with simple, fast and automatic operations. Each set of arms typically comprises at least three arms and preferably at least ten, preferably set at the same distance from one another. The arms extend preferably for at least half of the length of the bars to be handled. There is by no means excluded, on the other hand, the possibility of adding further arms or levers mounted on the bending units, even co-operating with the former, but this does not appear strictly necessary, given that, already as it is, the apparatus achieves a high degree of reliability.
Of course, the invention applies to any type of bending plant, with any conformation and arrangement of one or more bending units provided in the plant. Also the conformation of the stationary structure that receives the bars to be transferred onto the bending station may of course be altogether different from what is illustrated herein purely by way of example.
When the bars are unloaded into the receiving space 8 on the bending units 2, it could be possible for not all of them to be positioned correctly in the longitudinal direction A. To solve this problem, at least one of said bending units is provided with an element for arresting the bars and setting them head-on, said element being designed to function as contrast for one leading end of the bars after they are received in said receiving space so that the bending unit provided with said arrest element can be displaced in said longitudinal direction A in order to bring the arrest element up against the leading end of the bars, if necessary pushing them, and consequently forcing all the bars to assume a pre-set longitudinal position.
Furthermore, during the step of unloading of the bars onto the bending units, the latter are positioned longitudinally so as to prevent any interference with the arms of the device. When, after unloading has been carried out, the arms are raised again, the units can be set in the correct positions, in order to carry out the desired bending operation. During the movements of the units subsequent to unloading of the bars thereon, the bars B are gripped in their central part by clamping grippers (in themselves of a known type and not illustrated herein), set between the bending units 2, in the case where there are two or more of said units, or in any case adjacent to the bending unit 2 in the case where there is just one. Additional vices can be mounted on the at least one bending unit 2 for the purpose of withholding the bars during bending, but not during the movements of the at least one bending unit.
Of course, the various arms, in particular the arms 13, 14 and 15, but also 16, can move at a different rate according to the load. With just one bar or a few bars or, in any case, with bars of larger diameter and with favourable lengths or mechanical characteristics, the risks of improper dropping are reduced, and the arms can move faster.
Furthermore, in a preferred embodiment, the arms 13 and 14, as likewise possibly the structures 13A and 14A that connect them together, can translate in the direction perpendicular to the direction A for varying their distance from the receiving space 8 and/or from the central spindle 5. In this way, also the distance between the arrest fingers 13C and the receiving space 8 and/or the central spindle 5 is readily adjustable. Alternatively, it could be the bending units 2, or even just the structure 3, that translate in the same direction to obtain the same result. The most important parameters according to which the distances are to be adjusted are: the diameter of the bars; the length of the bars; the mechanical characteristics of the bars; the number of the bars; the diameter of the central spindle 5; and the diameter and position of the eccentric bending pin 6. Of course, it could be possible to displace also just the position of the arrest surfaces 13C.
Figures 11-13 illustrate a possible variant embodiment of the invention, according to which the arms 13 are without the respective arrest finger 13C, and each spindle 5 has, instead of the top prolongation 5A of the previous figures, a respective guiding and containment member, designated as a whole by 5B.
Said member 5B operates to guarantee that the plurality of bars B that is conveyed via the arms 13 and 14 in the direction of the intake mouth of the space 8 will be fed correctly, with the bars themselves arranged alongside one another so as to enter in succession within the space 8, without any criss-crossing or piling-up that could cause clogging or in any case a disorderly entry into the mouth of said space 8, as explained previously.
The principle of operation of the guiding and containment member 5B is exemplified in Figure 13. It should be noted that, for reasons of simplicity, in said figure the assembly constituted by the contrast element 7, the spindle 5 bearing the member 5B, and the underlying bending disk 4 has been represented as lying on a horizontal plane. In actual fact, however, the plane of lie of the aforesaid assembly is preferably inclined in order to facilitate movement by gravity of the bars B, as may be seen in Figures 11 and 12.
The guiding and containment member 5B, in its operative condition as illustrated schematically in Figure 13, defines a guiding and containment surface 5B' that overlies the space 8. More specifically, the guiding and containment surface 5B' is a surface inclined from the top downwards in the direction of the mouth of the space 8 for receiving the bars. In the example illustrated, the surface 5B' includes two portions having a different inclination which increases in the direction of the space 8. Alternatively, the guiding surface 5B' may be constituted by a curve with an inclination increasing from the top downwards in the direction of the space 8 for receiving the bars.
Thanks to the above solution, after the arms 13, 14 have reached the position visible in Figure 12, the bars B are free to slide or roll on the inclined top surfaces of the arms 14 and contrast element 7, until they hit against the guiding surface 5B', so as to be re-directed thereby, or "reflected" downwards, within the space 8. The inclination or curvature of the surface 5B' and the fact that it overlies the inlet mouth of the space 8 prevents, following upon impact, a bar from possibly "bouncing" back and thus returning onto the aforesaid top surfaces of the arms 14 and of the contrast element 7, falling astride of the subsequent bars. Of course, the slowest bars could enter the receiving space 8 directly, without hitting against the surface B', but for them there is no risk of any irregular entry.
In a further preferred embodiment, the guiding member 5B can be displaced into an inoperative position (not represented in the figures), in which it does not overlie the space 8 so as to enable raising of the bars B that have already undergone a bending operation outside the aforesaid space for receiving the bars in order to enable their unloading from the plant, it being possible for said raising to be carried out with modalities and means in themselves known (for example, extractor levers).
For said purpose, for example, the guiding member 5B can be connected in an articulated way to a respective support connected to the disk 4 and engaged in guides shaped in such a way as to cause displacement of the guiding member 13 between its operative position and its inoperative position on account of the movement of the bending disk 4 between a raised position thereof and a lowered position thereof (said movement of the disk 4 being moreover already envisaged in a preferred embodiment of the invention in order to facilitate particular bending operations).
Of course, at the moment when the disk 4 is raised again, the aforesaid support is raised along with it, and the guiding member 5B is forced to return into its operative position (illustrated in Figures 11-13) as a result of its engagement with the aforesaid guides.
In summary, operation of the plant according to the variant described with reference to Figures 11-13 is outlined in what follows.
The bars B received by the bench 10 are transferred by means of the system of arms 13, 14 into the spaces 8 for receiving the bars defined by the two bending units 2. In said step, the two members 5B for guiding and containment of the bars B associated to the bending units 2 are all in their operative condition so that they define the aforesaid guiding surface 5B' overlying the space 8 for receiving the bars. In this way, it is ensured that the bars B will be freely conveyed within the space 8 without any risk of criss-crossing or piling-up. Once the bars have all been received within the spaces 8, they are subjected to the pre-set cycle of bending operations. Said bending operations are carried out by controlling the rotation of the bending disks 4 of the bending units 2 and by displacing the bending units 2 in the longitudinal direction of the bars so as to make the bends in the various positions desired. The means provided for bending are of course of any type and in themselves do not form part of the present invention.
Once the bending cycle has been completed, the members 13 are displaced into their inoperative position. In the case of the bending units 2, this is obtained by lowering the two bending disks 4. In said condition, the bent bars can be taken out of the space 8 and unloaded, using any technique, at the side of the bending units.
Without prejudice to the principle of the invention, the details of construction and the embodiments may vary widely with respect to what is described herein.
In particular, it is pointed out that the plant according to the invention can be equipped with an intermediate supporting and vicing structure, provided, according to techniques in themselves known, in the space comprised between the two bending units 2, for supporting the bars B and keeping them stationary in their central part during the bending operation, or else for clamping the bars B when the distance between the bending units is varied.
In the case of implementation of the invention as illustrated in Figures 11-13, the aforesaid intermediate structure will preferably be provided with the member 5B for guiding and containment of the bars B. In this embodiment, the member 5B can be displaced between its operative position and its inoperative position by means of a kinematic mechanism actuated by a fluid-driven cylinder.

Claims

A plant for bending metal bars, in particular bars designed for the reinforcement of concrete, of the type comprising:

a stationary structure (11) having at least one supporting surface (12) for receiving the bars (B) arranged substantially parallel to one another; and

at least one bending unit (2) set adjacent to the stationary structure (11) and defining a bending surface and a space (8) for receiving one or more bars (B) to be bent on the at least one bending unit (2), arranged parallel to one another and aligned in a plane substantially orthogonal to the bending surface,

said plant being characterized in that:

it comprises means for automatic transfer of one or more bars (B) from the stationary structure (11) into said receiving space (8) on said at least one bending unit (2);

said transfer means comprise a plurality of first arms or levers (13), set substantially parallel to one another and directed in a transverse direction with respect to the longitudinal direction of lie of the bars on the stationary structure;

said first arms (13) are mounted on the stationary structure (11) and distributed in the longitudinal direction of lie (A) of the bars (B); and

means are provided for controlling a simultaneous movement of said first arms or levers (13) between a first position, in which they are designed to receive the bars (B) from said stationary structure, and a second position from which the bars (B) move until they enter said receiving space (8) on said at least one bending unit (2).
The plant according to Claim 1, characterized in that the top surface of said first arms or levers (13) for resting of the bars (B) has a cradle-shaped concave curved profile (13B).
The plant according to Claim 2, characterized in that said curved profile (13B) has one end facing the at least one bending unit (2), where an arrest surface (13C) of the bars (B) is defined.
The plant according to Claim 2, characterized in that said transfer means comprise at least one member (5B) for containment and guiding of the bars (B) during their conveyance into the space (8) for receiving the bars, said member (5B) being mounted on said at least one bending unit (2) and having an operative position, in which it defines a guiding surface (5B') partially overlying said space (8) for receiving the bars, and an inoperative position, in which it does not hamper unloading of the bars (B) from the space (8).
The plant according to Claims 1 to 4, characterized in that said transfer means further comprise a plurality of second arms or levers (14), which are also mounted on the stationary structure (11) and are distributed in the longitudinal direction of lie of the bars (B) on the stationary structures, said second arms or levers (14) being designed to co-operate with said first arms (13) for receiving the bars carried by said first arms (13) and for loading them then onto the at least one bending unit (2), where preferably said second arms (14) are mounted oscillating about an axis (A) substantially parallel to the longitudinal direction of lie of the bars (B).
The plant according to Claim 5, characterized in that said first and second arms (13, 14) are shaped and arranged in such a way that the bars (B) to be transferred to the aforesaid receiving space (8) are stopped against said arrest surfaces (13C) in a condition in which they are set alongside one another without criss-crossing, at a short distance from the aforesaid receiving space (8).
The plant according to Claim 5, characterized in that said first and second arms (13, 14) are shaped and arranged in such a way that at least some of the bars (B) to be transferred to the aforesaid receiving space (8) are able to hit against said guiding surface (5B') so as to be directed thereby downwards into said space (8), at the same time preventing them from bouncing back.
The plant according to Claim 5, characterized in that said transfer means comprise a plurality of third arms or levers (15) mounted on the stationary structure (11) and distributed in the longitudinal direction of lie (A) of the bars on the stationary structure, said arms or levers being mobile simultaneously between a first position substantially underneath the supporting surface (12) of the bars on the stationary structures and a position substantially above said surface in such a way that raising of said third arms or levers (15) from said first position to said second position brings about interception of the bars (B) that are located on said surface and their transfer on top of said first arms or levers (13), where preferably said third arms (15) are mounted oscillating about an axis (A) substantially parallel to the longitudinal direction of lie of the bars (B).
The plant according to any one of Claims 1 to 8, characterized in that it further comprises a plurality of fourth arms or levers (16) mounted on the stationary structure (11) and distributed in the longitudinal direction of lie (A) of the bars on the stationary structure (11), said fourth arms or levers (16) being mobile simultaneously between a first position substantially underneath the surface (12) for supporting the bars (B) on the stationary structure (11) and a second position substantially above said surface in such a way that raising of said fourth arms or levers from said first position to said second position enables unloading of the bars (B) that are not to undergo a bending operation on a side of the stationary structure (11) opposite to the side where one or more bending units (2) are provided, where preferably said fourth arms (16) are mounted oscillating about an axis (C) substantially parallel to the longitudinal direction of lie of the bars (B).
The plant according to Claim 1 or Claim 2 or Claim 3, characterized in that said first arms (13) are mounted oscillating about a longitudinal axis (A) substantially parallel to the longitudinal direction of lie of the bars.
The plant according to Claim 5, characterized in that the axis of oscillation of the second arms (14) coincides with the axis of oscillation (A) of the first arms (13).
The plant according to Claim 8 or Claim 11, characterized in that the axis of oscillation of the third arms (15) coincides with the axis of oscillation (A) of the first arms (13).
The plant according to Claim 9, characterized in that motor means are provided in the form of fluid-driven cylinders for controlling the movement of said first arms (13) and/or said second arms (14) and/or said third arms (15) and/or said fourth arms (16).
The plant according to Claim 5 or Claim 6, characterized in that said second arms (14) have a substantially rectilinear top edge designed to define an inclined plane, and in that said arms can be displaced between an inoperative raised position and a lowered position, in which said inclined plane is oriented so as to cause the bars received thereon to slide towards said receiving space (8).
The plant according to any one of Claims 5, 6 and 14, characterized in that the bending unit (2), or each bending unit (2), comprises an arrest surface (5A; 5B') adjacent to the receiving space (8), which guides the bars (B) that slide along the inclined plane defined by the aforesaid second arms (14) in their lowered condition into said receiving space (8).
The plant according to any one of Claims 5, 6, 14 and 15, characterized in that said first arms are designed to assume a lowered position, in which their top profile (13B) is located underneath the top edge of the second arms (14) when the latter are also in their lowered position in such a way that the bars carried by said first arms (13) are taken up by said second arms (14), where preferably, in said lowered position of the first arms (13), the arrest surfaces (13C) defined at the ends of said first arms project over the top edge of the second arms (14) so that the bars (B) carried by said arms are kept stationary in position by said arrest surfaces (13C).
The plant according to Claim 16, characterized in that the aforesaid first arms are designed to assume a further lowered position, in which also the arrest surfaces (13C) are located underneath the top edge of the second arms (14), so that the bars (B) previously stopped against the arrest surfaces (13C) are free to drop into the receiving space (8).
The plant according to any one of Claims 14 to 17, characterized in that the bending unit (2), or each bending unit (2), comprises an element (7) adjacent to the receiving space (8), which defines an inclined plane that is substantially coplanar with the inclined plane defined by the top edges of the second arms (14) when the latter are in their lowered position.
The plant according to any one of the preceding claims, characterized in that the bending unit (2), or each bending unit (2), comprises a structure (3) surmounted by a rotating bending disk (4) having a central spindle (5), an eccentric bending pin (6), said structure (3) of the bending unit, or of each bending unit, further carrying a contrast element (7), which defines, jointly with the central spindle (5), the aforesaid receiving space (8), where preferably:

said central spindle (5) is provided with a top prolongation defining an arrest surface (5A; 5B') for guiding the bars that drop into the receiving space (8); and/or

the aforesaid bending disk (4) has its axis (4A) that is vertical or inclined with respect to the vertical.
The plant according to Claim 1, characterized in that said plurality of first arms (13) carried by the stationary structure (11) comprises at least three arms, preferably at least ten arms.
The plant according to Claim 1, characterized in that said plurality of first arms (13) is distributed along the major part of the length of the bars to be handled and moved.
The plant according to Claim 1 or Claim 19, characterized in that it comprises two bending units (2), at least one of which can be positioned in one and the same direction parallel to the longitudinal direction (A) of the stationary structure (11), alongside the latter, and in that the stationary structure (11) is provided with a plurality of send-down resting surfaces, set adjacent to one another, which can be brought selectively into their operative raised position to provide a continuous resting surface for the bars (B) at least for a substantial part of the space comprised between the two bending units (2) or on the outside thereof, however the latter are positioned.
The plant according to Claim 1 or Claim 19, characterized in that it comprises two bending units (2), one of which or both of which can be positioned in one and the same direction (A) parallel to the longitudinal direction of the stationary structure (11), alongside the latter, and in that at least one of said bending units (2), which is mobile, is provided with an arrest element designed to function as contrast for one leading end of the bars B after they are received in said receiving space (8) so that the bending unit (2) provided with said arrest element can be displaced in said longitudinal direction (A) for the purpose of bringing the arrest element up against the leading end of the bars and of consequently forcing the bars (B) to assume a pre-set longitudinal position.
The plant according to Claim 22 or Claim 23, characterized in that it comprises an intermediate supporting and/or vicing structure located in the space comprised between the two bending units (2) for supporting and/or vicing the bars to be bent in their central part.
The plant according to any one of the preceding claims, characterized in that said supporting surface (12) is defined by at least one between:

the bottom of a channel (12) on a bench for cutting the bars to the desired length; and

a surface of a structure for receiving the bars in a bending plant, located in a remote position with respect to a bench for cutting of the bars.
The plant according to any one of the preceding claims, characterized in that said at least one bending unit (2) comprises, in a way in itself known, at least one between:

a central spindle (5) around which the bars (B) are bent; and

a central spindle (5) with a diametral slit, through which the bars (B) to be bent are engaged.
The plant according to Claim 1, characterized in that it comprises arrest means (13C) designed to intervene when said first arms are in an unloading position, for stopping the bars to be unloaded into said receiving space (8) at a short distance from said space so that a subsequent de-activation of the arrest means (13C) enables a slower and more orderly unloading of the bars into said receiving space (8).
The plant according to Claim 27, characterized in that said arrest means (13C) are carried by at least some of said first arms.
The plant according to Claim 27, characterized in that said arrest means (13C) are carried by said at least one bending unit (2).
The plant according to Claim 29, in which said at least one bending unit (2) comprises a structure (3) surmounted by a rotating bending disk (4) having a central spindle (5), an eccentric bending pin (6), and a contrast element (7), which defines, jointly with the central spindle (5), the aforesaid receiving space (8), said plant being characterized in that said arrest means (13C) are carried by said contrast element (7).
The plant according to any one of Claims 27 to 30, characterized in that said arrest means can be displaced into an inoperative position, preferably via motor-driven control means or fluid-driven cylinders.
The plant according to Claim 1, characterized in that said supporting surface (12) is formed by a resting surface for the bars on top of a chain conveyor, which comprises a plurality of closed-loop chains oriented in vertical planes transverse with respect to the bars.
The plant according to Claim 27, characterized in that said transfer means further comprise a plurality of second arms or levers (14), which are also mounted on the stationary structure (11) and are distributed in the longitudinal direction of lie of the bars (B) on the stationary structures, said second arms or levers (14) being designed to co-operate with said first arms (13) for receiving the bars carried by said first arms (13) and stopped against said arrest means (13C) and for loading them then onto the at least one bending unit (2).
The plant according to Claim 1, characterized in that it is equipped with at least one vice for withholding the bar or bars during bending, said vice being set at the side in the longitudinal direction (A) of the at least one bending unit (2) or at the edge thereof, said vice being preferably provided with a receiving space (8) and with an element (7) adjacent thereto that defines an inclined plane for enabling loading thereof with the same means with which the at least one bending unit (2) is loaded.
The plant according to any one of Claims 14 to 17, characterized in that the bending unit (2), or each bending unit (2) comprises an element (7) adjacent to the receiving space (8), which defines an inclined plane, which may be also one with variable inclination and is substantially coplanar, for an appropriate stretch, with the inclined plane defined by the top edges of the second arms (14) when the latter are in their lowered position.
The plant according to Claim 1 or Claim 9, characterized in that motor means are envisaged, which can operate with a number of speeds for controlling said first arms (13) and/or said second arms (14) and/or said third arms (15) and/or said fourth arms (16) .
The plant according to Claim 36, characterized in that the speed of said motor means is a function of one or more of the following parameters: the diameter of the bars; the length of the bars; the mechanical characteristics of the bars; the number of the bars; the diameter of the central spindle (5) of the at least one bending unit (2); and the diameter and position of the bending pin (6) of the at least one bending unit (2).
The plant according to Claim 9, characterized in that it comprises electronic control means programmed for reducing the dead times deriving from the differences of duration between the bending cycle and the cutting cycle, alternating appropriately steps of feeding cut bars to said bending units with steps of just cutting bars, which are then unloaded preferably on said side opposite to the bending units.
The plant according to Claim 1 or Claim 5 or Claim 6, characterized in that said first and/or second arms or levers (13) and (14) can be displaced, possibly with their connection structures (13A) and (14A), in the horizontal direction perpendicular to the axis (A) before, during, or after their working cycle.
The plant according to Claim 19, characterized in that the at least one bending unit (2) or even just the structure (3) can be displaced in the horizontal direction perpendicular to the axis (A).
The plant according to Claim 1 or Claim 19, characterized in that it comprises at least one bending unit (2), which can be positioned in a direction parallel to the longitudinal direction (A) of the stationary structure (11), alongside the latter, and in that the at least one unit (2) is provided with a hide-away resting surface, which can be retracted like a roller-shutter, to widen the resting surface of the bars of the at least one bending unit (2).
The plant according to Claims 3, 5, 6, 27, 28, 29, 39, and 40, characterized in that the distance between said receiving space (8) and said arrest means (13C) and/or the ends of the levers (13 and/or 14) is adjustable.
The plant according to Claim 42, characterized in that it comprises at least one bending unit (2) comprising a structure (3) surmounted by a rotating disk (4) having a central spindle (5) and an eccentric bending pin (6), and in that control of the computer is a function of:

one or more of the following parameters: diameter of the bars; length of the bars; mechanical characteristics of the bars; number of bars; diameter of the central spindle (5); and diameter and position of the eccentric bending pin (6);

at least one of the following distances: distance between the receiving space (8) and the arrest means (13C) and/or the ends of the levers (13 and/or 14); and distance between the central spindle (5) and the arrest means (13C) and/or the ends of the levers (13 and/or 14).
The plant according to Claim 35, characterized in that said element (7) has a decreasing inclination.
The plant according to Claim 35, characterized in that said element (7) in the terminal stretch has a chamfered portion, which facilitates entry of the bars (B) into the receiving space (8).
The plant according to Claim 18 or Claim 35, characterized in that the arms (14) and the elements (7) co-operate for unloading the bars (B) into the receiving space (8).
The plant according to one or both of Claims 39 and 40, characterized in that, as a consequence of the relative motion in the horizontal direction perpendicular to the axis (A) between the arms or levers (13) and/or (14) and the at least one bending unit (2) and/or the structure (3), the distance between the receiving space (8) and the arrest surfaces (13C) and/or the ends of the levers (13 and/or 14) varies.
The plant according to one or both of Claims 39 and 40, characterized in that the at least one bending unit (2) comprises a structure (3) surmounted by a rotating bending disk (4) having a central spindle (5) and an eccentric bending pin (6), and in that translation of the first arms or levers (13) and/or of the second arms or levers (14) and/or of the at least one bending unit (2) and/or of the structure (3) in the horizontal direction perpendicular to the axis (A) is controlled by a computer in such a way that the position reached is a function of one or more of the following parameters: the diameter of the bars; the length of the bars; the mechanical characteristics of the bars; the number of the bars; the diameter of the central spindle (5); and the diameter and position of the eccentric bending pin (6).
The plant according to Claim 18 or Claim 35, characterized in that it comprises further elements that define inclined planes, which can possibly be brought into a position in which they do not hamper movement of the bending unit (2) during their translation, said inclined planes being substantially coplanar for an appropriate stretch with the inclined plane defined by the top edges of the second arms (14), when the latter are in their lowered position, and with the inclined plane defined by the elements (7).
The plant according to one or both of Claims 39 and 40, characterized in that the at least one bending unit (2) comprises a structure (3) surmounted by a rotating bending disk (4) having a central spindle (5) and an eccentric bending pin (6), and in that, as a consequence of the relative motion in the horizontal direction perpendicular to the axis (A) between the arms or levers (13) and/or (14) and the at least one bending unit (2) and/or the structure (3), the distance between the arrest surfaces (13C) and the central spindle (5) varies.
The plant according to Claim 1, characterized in that the at least one bending unit carries further arms or levers co-operating with said first arms or levers (13).
A process for transferring metal bars, in particular bars designed for reinforcement of concrete, from a stationary structure (11), having at least one supporting surface (12) on which the bars (B) are arranged substantially parallel to one another, to at least one bending unit (2), arranged adjacent to the stationary structure (11) and defining a bending surface and a space (8) for receiving the bars (B) to be bent arranged parallel to one another and aligned in a plane substantially orthogonal to the bending surface,
said process being characterized in that:

there are provided means for automatic transfer of the bars (B) from the stationary structure (11) as far as within said receiving space (8) on said at least one bending unit (2);

said transfer means comprise a plurality of first arms or levers (13) substantially parallel to one another and directed transversely with respect to the longitudinal direction of lie of the bars on the stationary structure;

said first arms (13) are mounted on the stationary structure (11) and distributed in the longitudinal direction of lie (A) of the bars (B); and

a command is issued for simultaneous movement of said first arms or levers (13) between a first position in which they receive the bars (B) from said stationary structure and a second position from which the bars (B) move until they enter said receiving space (8) on said at least one bending unit (2).
The process according to Claim 52, characterized in that means are provided designed to define an inclined plane for loading the bars within .said receiving space (8) and means (13C) for stopping the aforesaid bars (B) on the aforesaid inclined plane in a condition in which the bars (B) are set alongside one another without any mutual criss-crossing at a short distance from the receiving space (8), and in that, following upon arrest of the bars in said position, said arrest means (13C) are removed so as to leave the bars free to drop within said receiving space (8).
The process according to Claim 52, characterized in that said transfer means comprise at least one member (5B) for containment and guiding of the bars (B) during their conveyance into the space (8) for receiving the bars, said member (5B) being mounted on said at least one bending unit (2) and having an operative position in which it defines a guiding surface (5B') at least partially overlying said space (8) for receiving the bars, said guiding surface being designed to deviate towards said space (8) the bars that impinge upon it.
The process according to any one of Claims 52-54, characterized in that it comprises two bending units (2) that can be positioned in one and the same direction (A) parallel to the longitudinal direction of the stationary structure, alongside the latter, and in that said bending units (2) are provided for receiving the bars to be bent in longitudinal positions in which the bending units (2) do not interfere with said arms or levers (13) and/or (14), and in that said arms or levers are retracted following upon unloading of the bars onto the bending units (2) to enable positioning of the latter in the their correct longitudinal positions prior to execution of the bending operation.
The process according to any one of Claims 52-55, characterized in that, during the longitudinal movements of the at least one bending unit (2) following upon loading of the bars (B), the latter are withheld in position via gripping means for gripping the intermediate portion of the bars.
The process according to Claim 53, characterized in that prior to arrangement of the bars on said inclined plane, the bars are pre-arranged on a plurality of arms or levers (13) designed to define a cradle-shaped resting surface for the bars, from which the bars are subsequently transferred onto the aforesaid inclined plane.
The process according to Claim 57, characterized in that a further plurality of transverse arms or levers (15) is provided, distributed in the longitudinal direction of lie of the bars, for transferring the bars from a stationary structure (11) to the aforesaid arms (13) defining the cradle-shaped resting surface.
The process according to any one of Claims 52 to 58 for automatic transfer of one or more metal bars, in particular bars designed for the reinforcement of concrete, onto one or more bending units (2), which define a bending surface and a space (8) for receiving one or more bars (B) to be bent, said bars being arranged parallel to one another and aligned in a plane substantially orthogonal to the bending surface, said process being characterized in that the portion at the end of the bar or bars that remains outside of the receiving space (8) after transfer depends upon one or more of the following parameters: the diameter of the bars; the length of the bars; the mechanical characteristics of the bars; the number of bars; the diameter of the central spindle (5) of the at least one bending unit (2); and the diameter and position of the bending pin (6) of the at least one bending unit (2).
The process according to Claim 52 or Claim 55 or Claim 59, characterized in that it comprises two bending units (2), one of which or both of which can be positioned in one and the same direction (A) parallel to the longitudinal direction of the stationary structure (11), alongside the latter, and in that at least one of said bending units (2), which is mobile, is provided with an arrest element designed to function as contrast for one leading end of the bars (B) after the latter have been received in said receiving space (8) so that the bending unit (2) provided with said arrest element can be displaced in said longitudinal direction (A) for the purpose of bringing the arrest element up against the leading end of the bars and of consequently forcing the bars (B) to assume a pre-set longitudinal position.