EP0108695B1 - Automatic machine for bending thin and rectilinear metallic elements, especially metal wire, into a spatial configuration - Google Patents

Abstract

1. An automatic machine for curving, according to a predetermined configuration, thin rectilinear metallic elements of constant thickness of the wire, strip or tube kind, this machine including a bending device (12) which comprises a distributor member (13) through which the element to be curved (1) may be inserted to extend beyond an outlet of said distributor member, a bending member (14) which is located downstream and in in the vicinity of the outlet of the distributor member (13) and which may, by means of a first drive mechanism (24), be driven with an angular rotational movement about a first axis (Y) perpendicular to the extending direction of the element to be curved, said curving machine further comprising first driving means (5) for generating a relative stepped feeding movement between the element to be curved and the bending device (12), as well as second driving means (49) for generating a relative angular rotational movement between the bending device (12) and the element to be curved (1) about a second axis (Z) merging with the extending direction of the element to be curved, the operations of the first driving mechanism and second driving means (24, 29) being synchronized with the operation of first driving means (5), according to a predetermined cycle, said curving machine being characterized in that the bending member consists in a bending finger (14) which is associated with a second drive mechanism (23) adapted to reciprocate said bending finger along a rectilinear path (X) parallel with said first axis (Y), the bending finger being supported in a frame (22) which is mounted for rotation about said second axis (Z) and on which said second driving means (49) act.

Description

The present invention relates to an automatic machine for bending, according to a predetermined configuration, thin and straight metal elements of constant thickness of the son, strip or tube type according to the preamble of claim 1, see US-E 27021. In this document it provision is made for the element to be bent to be subjected to angular rotation about the axis of the element to be bent.

Cambering machines of this type are currently the most efficient because of their automatic operation and the possibility that they offer of continuously bending thin and straight metal elements.

In these known machines, the use of which is generally limited to the bending of the metal wires with a view more particularly to the manufacture of folded wire articles, the angular rotation movement of the folding member occurs, at each folding cycle , between the back and forth strokes of its back and forth movement.

The succession of these movements makes it possible, first of all, to bring the folding member into lateral contact with the segment of wire emerging from the dispensing member, then to rotate it, at a certain angle, in a direction or in the other, so that it folds this segment of wire around the point of exit from the dispensing member and finally retracts it to allow the advance of the wire for the next folding cycle. The degree of wire bending is a function of the angle by which the bending member is rotated, while the length of the folded wire segment is determined by the pitch of the advancing device.

The essential mechanical element used in the construction of a bending machine of this known type, consists of a cylindrical bending head whose axis of symmetry is perpendicular to the direction of advance of the wire to be bent. On its face facing the outlet of the dispensing member, this head carries the actual folding member which is formed by a fixed finger eccentric with respect to the axis of symmetry of the head; the reciprocating movement of this folding member takes place under the action of a jack which moves the entire folding head while its angular rotation is produced by a stepping motor which rotates the folding head around its axis of symmetry.

In this first known machine, the particular structure of the folding member and of its drive means is the cause of a certain number of drawbacks.

The first of these drawbacks results from the large inertia of the folding head, which opposes the translational movement of the latter by causing a delay in response to the actuation of the jack, delay which is detrimental to the speed d execution and, consequently, the productivity of the bending machine.

Another drawback is inherent in the drive motor for angular rotation of the folding head which is not of sufficient precision for certain applications of the bending machine.

But the main drawback of this known cambering machine, as shown in the description of its operation made above, lies in the fact that it can only produce wires whose folds extend in one and the same plane. perpendicular to the axis of rotation of the folding member. In other words, it is not suitable for bending wires in all directions of space. However, in many fields of application and, in particular in the manufacture of car seat skeletons or skeletons, there is a need for metal wires bent in a spatial configuration.

To manufacture such wires, multiple slide machines are currently available. In these machines, the slides which are mounted side by side on the frame of the machine, comprise folding heads of different shapes cooperating with complementary counter-dies and can be oriented in any direction of space. Thus a wire placed between the folding heads of the slides and the associated counter-dies, can be bent, after actuation of the slides, according to a spatial configuration which is defined by the orientation and the working stroke of the slides as well as by the shape of their folding head.

It will be understood that this multiple slide machine is only of interest for bending long wires.

In addition, its profitability is only effective in the case of mass production, since each time it is desired to change the configuration or the bending pattern of the wire, it is necessary to replace the slides. in place by slides specially adapted to the new production envisaged, then to adjust the operation of the latter, this double operation can take two to three hours. Added to this is the fact that this multiple slide machine requires very high cost tooling.

The present invention proposes to remedy all these drawbacks and, to do this, it relates to a cambering machine of the type specified in the preamble, which is characterized by the characteristics of the characterizing part of claim 1.

Thanks to this arrangement, the axis of rotation of the folding member can be oriented in any direction, with respect to the metallic element inside a plane perpendicular to the direction of advance of this latest.

The folding member can therefore arch wires in all directions of space, and the machine according to the invention is able to produce, at a high and continuous rate, wires folded according to any configuration. spatial. It can thus be observed that the cambering machine according to the invention has all the advantages of the first machine as mentioned above for folding in a single plane, without having the disadvantages of the multiple slide machine for spatial folding.

According to preferred embodiments of the invention, the features of claims 2 to 9 are provided.

These embodiments of the cambering machine according to the invention are more particularly suitable for the manufacture of articles produced by folding a continuous metallic element, each finished article being separated from the latter by a shear which acts at the outlet of the distributor body.

By comparison with conventional cylindrical folding heads, this folding finger is of a very reduced weight and opposes an almost negligible inertia to the actuation of its movement mechanism. As a result, its back-and-forth movement is instantaneous, which has a favorable influence on the working speed and the productivity of the bending machine according to the invention.

In this case, the second folding finger drive mechanism comprises a jack integral with the frame, the rod of which passes freely through the support head along the axis of rotation of the latter, the free end of this rod. being connected to the folding finger by a rotating lateral link, which allows the folding finger to rotate around the cylinder rod while being able to be moved in translation by the latter, in any angular position.

In a preferred embodiment, the first folding finger drive mechanism comprises an endless chain driven parallel to the direction of advance of the wire around two toothed wheels, one of which is fixed coaxially around the support head and the other is carried by a loose shaft mounted for free rotation on the frame parallel to the axis of rotation of the support head, one of the strands of the endless chain being connected to the free end of the rod a cylinder which extends in the direction of drive of the endless chain.

This mode of driving the folding member in rotation has the advantage, on the one hand, of being very precise with regard to the repeatability of the folding angles and, on the other hand, of producing very low angular rotations up to 1/10 of a degree.

To increase the degree of precision of this second drive mechanism, a silent endless chain is used and it is further provided that the free end of the cylinder rod is slidably mounted along a guide rail parallel to the stem.

Furthermore, the third folding finger drive mechanism comprises a large diameter toothed wheel secured to the frame and centered around the axis of rotation of the latter, this large diameter toothed wheel meshing with a small diameter toothed wheel keyed to a shaft, which is driven, via a chain drive without play, by a stepping motor.

Finally, according to yet another characteristic of the invention, the various drive mechanisms of the folding member as well as the advance device are actuated in synchronism by a programmable digital control with assisted programming.

This arrangement considerably increases the productivity of the machine according to the invention in the case of medium series production or even small series. In fact, the operations of the drive mechanisms and of the machine advance device which determine the folding parameters are controlled synchronously by a program which contains a series of digital instructions and which can be recorded on a tape cassette. classic magnetic. Thus, the transition from one type of manufacturing to another simply requires a change of cassette in the playback device of the digital control cabinet, a change which can be carried out in a very short time of the order of two minutes.

• la fig. 1 est une vue de côté schématique avec arrachements de la machine à cambrer selon ce mode de réalisation de l'invention;
• la fig. 2 est une vue en coupe de son dispositif de pliage proprement dit, effectuée dans le plan de la fig. 1;
• la fig. 3 est une vue en coupe effectuée selon la fig. III-III de la fig. 2; et
• la fig. 4 est une vue représentant, partiellement en coupe, le troisième mécanisme d'entraînement de la machine à cambrer.

An embodiment of the cambering machine according to the present invention will be described below by way of nonlimiting example, with reference to the accompanying drawings in which:

• fig. 1 is a schematic side view with cutaway of the arching machine according to this embodiment of the invention;
• fig. 2 is a sectional view of its actual folding device, taken in the plane of FIG. 1;
• fig. 3 is a sectional view taken according to FIG. III-III of fig. 2; and
• fig. 4 is a view showing, partially in section, the third drive mechanism of the bending machine.

As shown in the appended figures, the machine is specially designed for producing articles of folded wire in succession, by bending a continuous metal wire. However, this is not a limiting application of this machine which, with a reduced number of structural modifications, can be used to produce articles produced by bending any other type of thin and straight metal elements, d constant thickness, such as strips or small diameter tubes.

This machine can also be used for bending simple segments of metallic elements of this type.

As can be seen in fig. 1, a continuous metal wire 1, coming from a motorized reel, not shown, first passes through a straightening device 2. This straightening device consists of a number of rollers 3 mounted free to rotate on the chassis 4 of the machine and arranged in staggered rows on two parallel rows which delimit a passage for the wire 1. By being drawn between the two rows of rollers, the wire which has a certain curvature at its exit from the reel, is made rectilinear. The height of the passage defined by the two rows of rollers can be adjusted by known means as a function of the diameter of the wire.

In alignment with and at the outlet of this straightening device is a step advancing device 5, housed in a casing 6 which is fixed to the chassis 4 of the machine. This advance device 5 consists of a movable clamp 7 and a fixed clamp 8. The movable clamp 7 is slidably mounted on a cylindrical rail 9 parallel to the direction of advance of the wire 1 and is fixed to the end of the rod 10 of a jack 11 carried by the casing 6. The fixed clamp 8 is in turn secured to the rail 9, near its end opposite the jack 11. The opening and closing of the two clamps 7 and 8 are controlled by conventional means known per se.

In this advance device 5, the movable clamp grasps the wire 1 which enters the casing 6 through an opening mj arranged in the rear wall of the latter. Then the fixed clamp 8 being open, the movable clamp 7, moved along the rail 9 by the jack 11, advances the wire 1 over a distance determined by the stroke of the latter. The fixed gripper is then closed and the jack brings the movable gripper back to its starting position in the open position for a new wire advance cycle 1. In this way, the movable gripper 7 advances the wire 1 according to a straight path and in successive steps not necessarily identical, in the direction of the folding device 12 of the machine.

As can be seen in fig. 1, this folding device 12 comprises a cylindrical distributor barrel 13 of circular section, which is secured to the chassis of the machine and which extends in the extension of the advance device 5 so as to direct the wire 1, moved in translation by the latter, at the level of a movable folding member 14 which ensures the actual bending of the segment of wire emerging from the dispensing barrel, around the point of exit of the latter. A shears 15 is also automatically brought, by an actuation system not shown, to the exit point of the dispensing barrel to separate by section each finished article from the wire 1.

As can be seen more precisely in FIG. 2, the wire 1 which enters the distributor barrel 13 through the end 16 thereof, located near the fixed clamp 8 of the feed device 5, is moved in translation inside a passage 17 s 'extending along the longitudinal axis of the barrel 13, before leaving the barrel through a tapered nozzle 18 removably mounted in the other end 19 of the barrel. The longitudinal passage 17 has a diameter significantly greater than the maximum diameter that the wire passing through it can have. On the other hand, the channel 20 of the nozzle 18 has a diameter strictly equal to that of the wire to be bent so that the latter slides without play inside the nozzle. Consequently, there must be a set of nozzles adapted to each diameter of wire to be bent. The chosen nozzle is fixed to the end 19 of the barrel 13 by a screw 21 but, as a variant, it is possible to provide, for the same purpose, a bayonet fixing.

As still shown in fig. 2, the movable folding member 14 is carried by a frame 22 so as to be disposed opposite and very close to the point of exit from the nozzle 18. Under the action of a first drive mechanism, 24, the folding member 14 can be driven by an angular rotation movement about an axis Y which extends perpendicularly to the direction of advance of the wire 1 in alignment with the point of exit of the distributor barrel 13. By elsewhere, a second drive mechanism 23 makes it possible to move the folding member 14 in a reciprocating movement on a rectilinear trajectory X parallel to the axis Y. By the combination of its two movements, the member bending 14 can be brought into lateral contact with the segment of wire leaving the barrel 13 and then bend it at a certain angle in one direction or the other around the tip of the nozzle 18. But as can easily be understood, a folding member having only these two possibilities of movement can only fold the wire in a plane perpendicular to its axis of rotation.

This is why, according to the main characteristic, the frame 22 which carries the folding member 14, is rotatably mounted around the cylindrical distributor barrel 13, by means of two bearings 25 and can be animated by a movement of angular rotation transmitted by a third drive mechanism which will be described later with reference to FIG. 4. Consequently, the folding member 14 has a third possibility of movement which consists of an angular rotation around a second axis coincides with the longitudinal axis of symmetry of the passage 17 of the barrel 13, that is to say with the direction of advance of the wire 1. By the combination of this third movement with the first two, the folding member 14 can bend wire 1 in all directions of space and the machine can produce wires bent in a spatial configuration.

According to a second characteristic, the folding member 14 is constituted by a cylindrical finger mounted sliding along the path X in a support head 26 which is itself kept in rotation inside the front part of the frame 22 by means of two bearings 27, 28. The folding finger 14 is eccentric relative to the axis of symmetry of the head of the support 26, which in fact constitutes the axis of rotation Y mentioned above.

Under the action of the second mechanism 23, the folding finger 14 can sometimes be taken out of its support head 26 for positioning against the wire 1, sometimes retracted to allow the wire 1 to advance at the end of a folding cycle. It will be observed that, by its reduced weight, the folding finger 14 opposes a practically negligible inertia to the action of the drive mechanism 23; its back-and-forth movement is therefore instantaneous, which has the consequence of increasing the working speed and the productivity of the bending machine.

The drive mechanism 23 more specifically comprises a hydraulic cylinder 29 fixed to the upper wall 30 of the frame 22, in which an opening 31 is made through which the rod 32 of the cylinder is formed. Cylinder rod 32 grout cross member the support head 26 along the axis Y is free and, at its free end, opens into an interior cavity 35 of the support head where it is connected to the folding finger 14 by a rotary link 36. Thanks to this connection, the finger 14 can be rotated about the axis Y while being able to be moved in translation by the rod 34 whatever its angular position.

The first drive mechanism 24 of the folding finger 14 which can impart to it this angular rotation movement around the axis Y, is housed in an interior cavity 33 of the frame 22.

Referring simultaneously to Figures 2 and 3, we can see this first drive mechanism 24 which first includes an endless chain 37 whose representation has been omitted for clarity in FIG. 2. This endless chain 37, which is preferably a silent chain, cooperates with two toothed wheels 38, 39, one of which 38 is fixed coaxially around the support head 26 and the other 39 is carried by a shaft idler 40, kept in rotation in the frame 22 so that its axis of rotation is parallel to that of the support head. The two strands of the endless chain 39 are thus parallel to the direction of advance of the wire 1, and one of them is connected by a connecting link 41, to the end of the rod 42 of a jack. hydraulic 43 fixed to the rear face 44 of the frame 22. The free end of the jack rod 42 is also slidably mounted by means of a ball bushing 45, along a cylindrical rail 46 parallel to the direction of advance of the wire and fixed by its ends to the frame 22.

It will be understood that, thanks to this mechanism, the endless chain 39, driven in one direction or the other by the jack 43, rotates the support head 26 by an angle determined by the stroke of the jack rod, this angular rotation being transmitted to the folding finger 14 which describes an arc of a circle with the same angle in the center, around the axis Y. Thus, the folding finger 14, in lateral contact with the wire 1, can bend the latter in a plane perpendicular to the axis Y, the degree of folding obtained being a direct function of the stroke of the rod of the jack 43.

It will be observed here that this second drive mechanism is very precise. It makes it possible to produce very small angular rotations of the bending finger of the order of 0.1 °, which allows the latter to perform bends according to non-polygonal curves and in particular according to arcs of a circle.

The finger 14 exerts its folding action on the wire 1 by means of a V-shaped groove 47 which adapts to all the wire diameters. The folding finger is further mounted with the rotary link 36, inside a removable cover 48 which is fixed to the rotary head, the rotary link coming to be snapped on to the free end of the rod 32 .

The bending plane of the wire 1 is determined, before the finger 14 comes into action, by the third drive mechanism 49 which will now be described with reference to FIG. 4.

As can be seen, this third drive mechanism 49 comprises a large diameter toothed wheel 50 secured to the frame 22 and centered around the axis of rotation Z of the latter. The toothed wheel 50 meshes with a toothed wheel of small diameter 51 which is keyed onto a fixed shaft 52 and which is driven by a stepping motor (of which only the shaft 54 is visible in FIG. 4), by the intermediate a silent chain transmission 53 forming a backlash without play. The chain transmission 53 comprises an endless chain 55 winding around two toothed pinions 56 and 57, respectively integral with the shaft 52 of the small toothed wheel and the motor shaft 54. The endless chain 55 is further tensioned by an adjustable tension roller 58.

It will be understood that, in this third drive mechanism 49, a given angular displacement of the large toothed wheel 50 around the axis of rotation Z systematically orients in a desired direction, the axis of rotation Y and therefore the bending plane of wire 1, which is thus determined by the pitch of rotation of the motor.

The assembly constituted by the chain transmission 53, the small toothed wheel 51 and the stepping motor is housed inside a protective casing 59, which is partially open at the level of the gear of the two toothed wheels 50 and 51 and can be moved, perpendicular to their axis of rotation, for adjusting the backlash.

In fig. 4 are also shown support pins 60 arranged in a spiral and around which the supply pipe 61 for hydraulic fluid under pressure of the jack 43 is wound during the various rotations of the wheel 50.

The different cylinders 11, 29 and 43 of the bending machine are, as can be seen in FIG. 1, supplied with pressurized fluid by a hydraulic unit 62, under the control of a digital control panel shown diagrammatically by a square under the reference 63. The motor for rotating the frame 22 as well as the actuation device for the shears 15 are also controlled by this digital control console.

The digital control panel contains a reading device into which a magnetic tape cassette can be inserted, on which a program is pre-recorded in the form of a succession of digital instructions which govern and synchronize the operations of the various mechanisms of drive 23, 24, 49, of the advance device 5 and of the device for actuating the shears 15 of the machine according to the type of article of bent wire which it is desired to produce.

More precisely, these instructions relate, for each folding cycle, to the speed and the angle of rotation of the folding finger 14 around the two axes Y and Z, to the length and to the speed of advance of the wire, at the diameter of the latter and at the time of intervention of the shears 15.

The program also allows an automatic search for the origins of the different movements. ffients of the bending machine and fault management.

It will be understood that this programmable digital control makes it possible to considerably increase the profitability in the case of a medium or small series production, since a change in the type of production requires only one replacement of one program cassette by another. The program of an article can also be viewed on a standard video screen in the form of a table and the operator has the possibility of modifying any parameter of the table by the cursor of the video screen.

It is also worth emphasizing the particularly high working speed of the bending machine. By way of illustration, it can be mentioned that the speeds of rotation of the folding finger around the axes Y and Z can reach 277 rpm and 66 rpm respectively and that the speed of advance of the wire can go up to 1 m / s.

Among the advantages of the cambering machine according to the invention, one can also cite its great flexibility of use. Indeed, it can bend metal wires whose diameter can reach 8 mm as well as metal strips or ribbons. For folding the strips or ribbons, it is of course necessary to adapt the shape of the central passage 17 of the dispensing barrel 13 and of the channel 20 of the nozzle 18 accordingly. The machine according to the invention can even produce bent tubes , more particularly thanks to the very high precision of the second drive mechanism 24 of the folding finger 14, which allows bending in an arc by successive close keys.

Claims (9)

1. An automatic machine for curving, according to a predetermined configuration, thin rectilinear metallic elements of constant thickness of the wire, strip or tube kind, this machine including a bending device (12) which comprises a distributor member (13) through which the element to be curved (1) may be inserted to extend beyond an outlet of said distributor member, a bending member (14) which is located downstream and in in the vicinity of the outlet of the distributor member (13) and which may, by means of a first drive mechanism (24), be driven with an angular rotational movement about a first axis (Y) perpendicular to the extending direction of the element to be curved, said curving machine further comprising first driving means (5) for generating a relative stepped feeding movement between the element to be curved and the bending device (12), as well as second driving means (49) for generating a relative angular rotational movement between the bending device (12) and the element to be curved (1) about a second axis (Z) merging with the extending direction of the element to be curved, the operations of the first driving mechanism and second driving means (24, 29) being synchronized with the operation of first driving means (5), according to a predetermined cycle, said curving machine being characterized in that the bending member consists in a bending finger (14) which is associated with a second drive mechanism (23) adapted to reciprocate said bending finger along a rectilinear path (X) parallel with said first axis (Y), the bending finger being supported in a frame (22) which is mounted for rotation about said second axis (Z) and on which said second driving means (49) act.

2. The curving machine according to claim 1, characterized in that the bending finger is slidably mounted in a support head (26) which has an axis of symmetry forming the first axis (Y) and which is held for rotation about his axis inside the frame (22), the first and second drive mechanisms (24, 23) acting respectively on the support head (26) and the bending finger (14).

3. The curving machine according to claim 2, characterized in that the second mechanism (23) for driving the bending finger (14) comprises a piston and cylinder device (29) firmly fixed to the frame and whose piston rod (32) slides freely through the support head (26) along the axis of rotation (Y) of this latter, the free end of this rod (32) being coupled with the bending finger (14) by a rotary lateral connection (36).

4. The curving machine according to claim 2 or 3, characterized in that the first mechanism (24) for driving the bending finger (14) comprises an endless chain (37) extending parallel with the second axis (Z) around two toothed wheels (38, 39), one of which (38) is fixed coaxially around the support head (26) and the other (39) is supported by an idle shaft (40) mounted for free rotation on the frame (22) and parallel with the axis of rotation (Y) of the support head, one of the runs of the endless chain (37) being connected with the free end of the rod (42) of a piston and cylinder device (43) which is parallel therewith.

5. The curving machine according to claim 4, characterized in that the endless chain (37) is a silent chain.

6. The curving machine according to claim 4 or 5, characterized in that the free end of the rod (42) of the piston and cylinder device (43) is mounted for sliding along a guide rail (46) parallel with the rod (42).

7. The curving machine according to any one of claims 1 to 6, characterized in that said second driving meand (49) comprise a large-diameter toothed wheel (50) firmly fixed to the frame (22) and centered about the axis of rotation (Z) of this latter, this large-diameter toothed wheel meshing with a smaller-diameter toothed wheel (51) keyed to a shaft (52) and driven, through a chain transmission withour play by a stepper motor.

8. The curving machine according to any one of claims 1 to 7, characterized in that the first and second drive mechanisms (23, 24) as well as the first and second driving means (5, 49) are actuated in synchronism by a programmable digital control with assisted programming.

9. The curving machine according to any one of claims 1 to 8, characterized in that the distribu- _tor member (13) is formed by a cylindrical barrel of circular cross section, the axis of symmetry of which forms said second axis (Z), and in that the frame (22) is mounted for rotation about this cylindrical barrel.

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