EP1543891A1

EP1543891A1 - Locking device

Info

Publication number: EP1543891A1
Application number: EP04078322A
Authority: EP
Inventors: Anders Alrutz
Original assignee: Herber Industri AB
Current assignee: KMT HERBER AB
Priority date: 2003-12-18
Filing date: 2004-12-07
Publication date: 2005-06-22
Also published as: SE0303427D0; SE526757C2; SE0303427L

Abstract

A tool (1) which is included in a machine has a locking position and an open position. The tool (1) or a part thereof is movable between the locking position and the open position. A locking device (2) for the tool (1) includes a movable guide (11) and a carrier member (10) which is guided in the guide (11, 12). The carrier member (10) is motionally connected to the tool (1) for realising the movement of the tool (1) between the locking position and the open position.

Description

TECHNICAL FIELD

The present invention relates to a locking device for a tool included in a machine, having a locking position and an open position, the tool being movable between the locking position and the free position, and vice versa.

BACKGROUND ART

For moving and locking tools in different types of machines, use has long been made of an extensive range of different types of locking devices.
One commonly occurring type of locking device is a hydraulic system. The hydraulics can either act directly on the tool or via a linkage system, for example an elbow joint lock. While these systems give the desired locking force, there are nevertheless drawbacks inherent in this type of system. A first drawback resides in the hydraulics themselves, with the handling of hydraulic fluid, the risk of leakage, service and maintenance of the hydraulic system etc. Other drawbacks are that specific hydraulic systems with an elbow joint lock require quite a number of components in order to function, and that the systems readily become unwieldy. A further drawback is that the speed of movement is limited, since the dimensions of the system restrict the flow of the hydraulic fluid therein.
Pneumatic systems are generally combined with an elbow joint lock. These systems also per se give the locking force, but like the hydraulic systems, pneumatic systems also become bulky and unwieldy, not least because so many components are included. Moreover, these systems function best in long movements of tools, while shorter movements are difficult - not to say impossible - to achieve with the requisite precision. This is essentially because of the resilient action inherent in the air of the system..
A further alternative for realising the movement and locking of the tool is to provide a ball screw, i.e. a screw with balls in its threads. One advantage with this construction is that it is well suited for electric operation, while the drawbacks are that the construction readily becomes unwieldy, that the moving and locking cycle is relatively slow and that the force that is generated is often insufficient to provide for the intended locking.

PROBLEM STRUCTURE

The object of the present invention is to realise a compact locking device which, on the one hand, displays rapid movement, and, on the other hand, delivers considerable force in the locking position.

SOLUTION

The object forming the basis of the present invention will be attained if the locking device intimated by way of introduction is characterised in that the device includes a movable guide and a carrier member guided in the guide which is motionally connected to the tool for realising the movement of the tool between the locking position and the open position, or vice versa.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will now be described in greater detail hereinbelow, with particular reference to the accompanying Drawings. In the accompanying Drawings:

Fig. 1: is a straight side elevation of the locking device according to the present invention in an open position, the device forming part of a pipe bending machine;
Fig. 2: is a view corresponding to that of Fig. 1 of the locking device and the bending tool in the pipe bending machine in a locking position;
Fig. 3: is a perspective view from the opposite side of the locking device and the bending tool according to Figs. 1 and 2, the locking device being in its open position;
Fig. 4: is a top plan view of the bending tool; and
Fig. 5: is a perspective view of the moving guide included in the locking device according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENT

The present invention will be exemplified hereinbelow as applied to a pipe and profile bending machine which has a tool with two parts 4 and 5 which are reciprocally movable towards and away from one another between a closed position where they are urged against one another with a locking force, and an open position where a workpiece may be placed in, moved in or removed from the tool. However, the present invention may advantageously also be applied to other types of machines and tools where the above-outlined functions and requirements also apply.
Fig. 1 shows a part of a pipe bending machine. In the illustrated part, there is included a separable bending tool 1 which is locked by a locking device 2 according to the present invention. Further, there is provided a motor 3 for driving the locking device 2 and a part of the bending tool 1 movable therethrough.
Thus, the bending tool 1 is separable into two different parts 4, 5 which are reciprocally movable towards and away from one another and simultaneously rotary about a substantially vertical axis Y. While the tool is shown in its open position in Fig. 1, it is shown in its locking position in Fig. 2. When observing Fig. 2, it will be apparent that the straight part 5 has moved a distance to the left in the Figure compared with Fig. 1.
In the preferred embodiment, the locking movement is substantially realised by the straight part 5 along a slide 6, while the bending of the pipe is carried out around the bending part 4. The vertical axis Y about which rotation of the tool 1 takes place extends through a centre axis through the bending part 4.
Fig. 3 shows the tool in its open position and the slide 6 is also visible. On both the bending part 4 and the straight part 5, there is provided, in the preferred embodiment, a series of recesses 7 for receiving the pipes that are to be bent. When the parts 4 and 5 included in the tool 1 are moved towards one another to the locking position, the recesses 7 in each respective part 4 and 5 meet and provide a gripping retention of the pipe, as is best apparent from Fig. 2.
The parts 4, 5 included in the bending tool 1 are rotary about the substantially vertical axis Y. The bending part 4 displays a series of different radii at different levels along the axis Y. These radii affect the appearance of the bent pipe, more precisely how sharp the bend will be. The bending part 5, as well as the straight part 5 are replaceable so as function for different pipe dimensions and bending radii. The degree of bending is also affected by the degree of rotation of the bending tool 1 in the bending operation.
Fig. 4 shows, in a top plan view, the bending tool 1 with the included parts 4 and 5 which, together with the slide 6, are rotary about the axis Y. In Fig. 4 can be seen a pipe 5 during its bending. An abutment 16 abuts against the pipe 15 in order to ensure that the pipe 15 is bent at the intended place, but is otherwise held straight. Possibly, an additional locking device 2 according to the invention may also be included so as to move the abutment 16 to and from its working position.
A chuck 17 fixedly holds the pipe 15 during the bending phase and advances the pipe 15 predetermined distances between several bending operations in order to realise complex pipe configurations. In addition, the chuck 17 is capable of rotating the pipe about its longitudinal axis between the bending operations so that a series of bends gives a pipe configuration with a spatial extent rather than in a single plane. It readily follows from this that the bent end of the pipe may assume an unwieldy configuration and that, as a result, it is of crucial importance that the bending machine is as a compact as possible in order to make maximum room for the pipe.
In order to parry reaction forces from the pipe 16 which is in the process of being bent, there is provided a transverse boom 8 between the bending part 4 and a fixed turret 9 in the machine. The reaction forces strive to force apart the parts 4 and 5 included in the bending tool 1 when they are rotated about the axis Y. The forces will be particularly powerful at the edges of the recesses 7.
The bending tool 1 is well suited for mass production where a large number of pipes of the same dimension are automatically fed into the machine. A high speed is desirable both in the automatic infeed and during the gripping of the pipes in the tool 1, and in the bending process proper. This places corresponding demands on the locking device 2 in that it must attain rapid movement in the straight part 5, at least during the greater part of the movement to and from the free position. Further, the locking device 2 must realise a powerful locking of the separable tool 1. Thus, considerable force is required from the locking device 2 close to the locking position of the bending tool 1.
The locking device 2 is connected to the straight part 5 of the bending tool 1 by the intermediary of a carrier member 10. The carrier member 10 is movable along a line simultaneously with the straight tool part 5, preferably in a slide 6. The direction of this movement is designated the X-direction. The simultaneous movement implies that an action on the carrier member 10 will realise a movement of the straight tool part 5, at least to the extent the movement takes place in the X-direction. When the carrier member 10 is actuated in the X-Z plane, the slide 6 only permits that the component of the force which is directed in the X-direction is transferred to the tool part 5. The slide 6 blocks the force in the Z-direction. Thus, that movement which the force realises on the carrier member 10 and the tool part 5 is a movement in the X-direction.
In the preferred embodiment, a movable guide 11 is disposed below the bending tool 1 in order to transfer the movement to the carrier member 10. The design of the movable guide 11 is such that its own movement realises that movement obtained by the carrier member 10. This is attained in that the movable guide 11 is provided with a groove 12 in which the carrier member is guided.
Since other movements than those in the X-direction are blocked by the slide 6, the movements of the guide 11 in other directions than the X-direction are immaterial. What is significant is the force which actuates the carrier member 10 to a movement in the X-direction, and that the movement of the guide 11 permits a compact construction of the guide 11 and the entire locking device 2.
In an opening or locking movement of the guide 11, the carrier member 10 will be guided in a path which depends on the design of the movable guide 11 and its movement.
In the preferred embodiment, the guide 11 is designed as a groove 12. Since only movements along the direction of the slide 6, i.e. in the X-direction, will be received by the carrier member 10 and transferred to the tool 1, it is essentially the edges of the groove 12 that are in contact with the carrier member 10. This type of guiding is also called desmodromic guiding or positive guiding. The groove 12 in the guide 11 is also designated a cam surface. In the preferred embodiment, the carrier member 10 is designed as a roller that runs freely in the groove 12.
In the preferred embodiment, the guide 11 is in the form of a cylinder 13 in which the groove 12 is disposed. This is apparent in detail from Fig. 5. The guide 11 is hereby given extremely compact design, since the groove 12 is curved in the circumferential surface of the cylinder 13. This design also affords excellent possibilities for realising, in a simple manner, the movement of the guide 11, more precisely in that the cylinder 13 rotates in either direction about its centre axis.
The design of the groove 12 also gives an adaptation of the movement, and in particular its speed, in relation to the speed of the cylinder 13. The configuration of the groove 12 in the cylinder 13 corresponds to the thread of a screw of variable pitch. In the regions where the groove 12 is steepest, the speed of the movable carrier member 10 in the groove 12 will be at its highest in relation to the speed of rotation of the cylinder 13. In those areas where the groove is flat, i.e. where the thread pitch is least, the speed will be slowest in relation to the speed of rotation of the cylinder 13. The pitch of the groove 12 also affects the direction of the contact force that occurs between the carrier member 10 and the edges of the groove 12. Since the contact force is a normal to the edge of the groove 12, this implies that the force in the X-direction, i.e. in the direction of the slide 6, is at its greatest when the pitch of the groove 12 is at its lowest. In other words, obtain a greater force when the carrier member 10 is located in that part of the groove 12 which corresponds to the locking position of the bending tool 1.
The transitions between the different pitches in the groove 12 must be gentle in order to obtain smooth and problem-free operation. The cycle where the moving part 5 moves from the open position to the locking position or the reverse is relatively rapid, typically within one or a few hundredths of a second. Possible unevenness in the groove 12 would consequently give rise to undesirable contact forces, vibrations or jolts which would run the risk of reducing the service life of the locking device 2. Moreover, an unnecessarily high level of noise would be generated.
Realising such a groove 12 with varying pitch has proved to be extremely complicated in practice. One method is by hand, with careful testing, for realising the groove 12 which is in the form of a helix whose pitch varies throughout all of its length. Hence, the groove 12 lacks sections where the pitch is totally constant, even if changes along the distance passed are very slight in certain sections. Another method of realising the groove 12 is to utilise advanced CAD programs in the design and construction. The construction must then give a number of helices of different constant pitches in different sections. The computer software then calculates a helix with varying pitch. This helix is to be considered as a composition of the originally disclosed, but the new composite helix has a pitch that constantly varies. As a result, there are no well-defined transitions between those pitches that were originally disclosed. The new helix is a unit that could be difficult - or even impossible - to realise using manual calculations. In practical trials, it has proved that at least three different helices must be disclosed initially, otherwise the variation in pitch in the composite helix would be far too great in the application disclosed in the preferred embodiment.
The rapid cycles in locking and opening of the bending tool 1 also entail that a minimisation of the inertia of the cylinder 13 is desirable. Consequently, the intention is to minimise its mass as far as possible without its mechanical strength being reduced to any appreciable degree. In the preferred embodiment, this has been solved in that a series of foraminations 18 are provided in the cylinder 13 in those parts of the cylinder 13 where no groove 12 is provided. The quantity of material included in the cylinder 13 is reduced so that the force that is required for accelerating and retarding the cylinder 13 to the desired speed will be a slight as possible.
In the preferred embodiment, the motor 3 is electric. This in general gives a compact motor that may be placed close to the moving cylinder 13. In the preferred embodiment, the motor 3 is connected via a transmission 14 to the cylinder 13. The compactness of the entire construction enjoys the advantage that there is plenty of space for the partly bent pipe during the bending process. The reason for this is that, in certain machines, where the motor is far too bulky, it is impossible to bend certain types of complicated bent pipes, since the bent pipe has, after a number of sequential bends, such a spatial extent that it is difficult or impossible to apply further bends without the already bent section of the pipe slamming against some part of the machine during the bending movement.
In the preferred embodiment, the motor is also provided with a torque guide where the maximum permitted torque is adjustable. Since the pitch of the groove 12 affects the torque, the varying pitch will give a varying force. Close to the open position of the tool, the force is at its slightest, which reduces the risk of serious contusion or crushing injury in the event of an accident. On the other hand, close to the locking position, the desired powerful locking force is obtained.

DESCRIPTION OF ALTERNATIVE EMBODIMENTS

In the preferred embodiment, the guide is shown as a cylinder 13. It is naturally also possible to make the movable guide 11 planar. A planar disk with a wholly or partly through-going groove however enjoys the advantage that it can realise force and movement in one angle in the plane to its own direction of movement, on condition that the guide is given a design which is suitable for this purpose. This may be interesting in certain applications, where special requirements are placed on the rest of the design of the machine.
In the preferred embodiment, the groove 12 was at its steepest in the position corresponding to the open position of the tool, so that this is given maximum speed in this region, while the speed is reduced when the tool part 5 approaches the locking position of the tool 1. If another speed pattern is desired, for example a slow movement close to both end positions of the moving part, the groove is designed accordingly.
The locking device 2 according to the invention may also be disposed on other tools and in other positions in a pipe bending machine, for example for supporting the pipe during the bending process or for functioning as an abutment which takes up a part of the reaction forces from the pipe during the bending operation.
Correspondingly, it is also naturally possible to dispose the locking device 2 according to the present invention also in other types of machines where a corresponding movement is required between an open position and a locking position. A number of examples of such machines are injection moulding machines, die casting machines, other casting machines and multi-operation machines, in particular retention jaws in such machines.
The present invention may be modified further without departing from the scope of the appended Claims.

Claims

A locking device for a tool (1) included in a machine, having a locking position and an open position, the tool (1) or a part (5) thereof being movable between the locking position and the open position, and vice versa, characterised in that the device (2) includes a movable guide (11, 12) and a carrier member (10) guided in the guide (11, 12) and motionally connected to the tool (1) for realising the movement of the tool (1) between the locking position and the open position, or vice versa.
The locking device as claimed in Claim 1, characterised in that the movable guide (11, 12) is designed as a groove (12) in the circumferential surface of a cylinder (13) which is rotary about its centre axis.
The locking device as claimed in Claim 2, characterised in that the groove (12) is of helical configuration with varying pitch along the longitudinal direction of the cylinder (13).
The locking device as claimed in Claim 3, characterised in that the pitch is steepest in that section of the groove (12) which corresponds to that part of the linear movement which is most proximal the open position and is flatter proximal the locking position.
The locking device as claimed in any of Claims 1 to 4, characterised in that the movement of the guide (11, 12) is realised by means of an electric motor (3).
The locking device as claimed in Claim 5, characterised in that the electric motor (3) has a torque limiter.
The locking device as claimed in any of Claims 1 to 6, characterised in that the carrier member (10) is a roller.
The locking device as claimed in any of Claims 1 to 7, characterised in that the machine is a pipe or profile bending machine.