FR3138058A1 - DEVICE FOR GRIPPERING A PROFILE TO BE BENDED - Google Patents

Abstract

Device for gripping a tube to be bent comprising: - a first disc (2) with a first toothed peripheral ring (8) and a housing (6) for a tube, - a system for holding a tube (12), - a second disk (4) with a second peripheral ring (8), mounted coaxially with the first disk (2), - a control system (16, 18, 20) of the holding system (12), - a motor ( 28) intended for rotating a disc via a first transmission (42, 44) comprising a driving wheel (42), - a second transmission between said driving wheel (42) and the other disc, with three toothed wheels (46, 48, 50), the axes of rotation of the three toothed wheels and the driving wheel defining articulations of a deformable parallelogram, and - control means (30) for modifying the relative position of a toothed wheel (46) relative to the driving wheel (42). Abstract Figure: Figure 1

Description

DEVICE FOR GRIPPING A PROFILE TO BE BENT

The present disclosure relates to a device for gripping a profile to be bent, for example a tube or a bar.

This disclosure relates to the field of machine tools and more particularly to profile bending machines. Since it is more common to bend tubes, subsequently when it comes to tube bending, the bending of any profile will be concerned,

It is known to have a gripping head in a bending machine in order to position a tube for bending and prevent any rotation of the tube. The tube to be bent must be able to be gripped radially over its entire length. It is known to have a disc-shaped head with a radial slot. A tube can then be introduced radially towards the center of the disc.

Several technologies exist to grip a tube:
- self-locking jaws (kept closed by a knee lever or spring) and unlocked at a single point,
- grippers equipped with two disks driven by two independent motors. In this case, by rotating the disk, the tube is rotated around the axis of the disk (which corresponds at least locally to the longitudinal axis of the tube).

Self-holding systems have only one opening position or are limited in rotation. Systems equipped with two motors are more expensive and require the ability to be synchronized and desynchronized from a software point of view.

The purpose of the present disclosure is to provide a system which makes it possible to make the tube holding clamp independent of the rotation of the disk in order to be able, on the one hand, to open the holding clamp in all positions of the disk and, on the other hand, to be able to rotate the disk with the tube held relative to the disk without any limitation of rotation angle (any angle even greater than 360°). Advantageously, the proposed solution can operate with a single electric motor.

Summary

This disclosure improves the situation.

A device for gripping a tube to be bent is proposed comprising:
- a first disk with a first center and a first peripheral toothed crown, said disk having in its center a housing for a tube,
- a system for holding a tube placed in the center of the first disk, said system being mounted on a face called the front face of said first disk,
- a second disk with a second center and a second peripheral crown, mounted coaxially with the first disk, said disk having in its center a housing for a tube,
- a control system such that a relative rotational movement of the second disc relative to the first disc controls the tightening and loosening of the holding system,
- a motor with an output shaft, said motor being intended for driving in rotation a disk, chosen from the first disk respectively the second disk, by means of a first transmission comprising at least one toothed wheel, called a drive wheel.

According to the present disclosure, the gripping device further comprises:
a second transmission between said drive wheel of the first transmission and the other disk, corresponding to the second disk respectively to the first disk; the second transmission comprises at least three toothed wheels each having an axis of rotation:
- a first toothed wheel meshing with the drive wheel while being mounted on an axis movable relative to the axis of the drive wheel,
- a second toothed wheel driven by the first toothed wheel while being mounted on an axis movable relative to the axis of the drive wheel, and
- a third toothed wheel meshing, on the one hand, with the second toothed wheel and, on the other hand, directly or indirectly, with the peripheral crown of the other disc,
the axes of rotation of the three toothed wheels and the drive wheel defining articulations of a deformable parallelogram, and
control means are provided for modifying the relative position of the axis of rotation of the first toothed wheel with respect to the axis of rotation of the drive wheel.

In this device, the motor drives a disk of the gripping device by a first transmission. From a wheel of this transmission, a second transmission is provided for driving the other disk of the gripping device. Means are provided between the first and second transmissions (or within the second transmission) to provide an additional degree of freedom relative to the motor. The deformable parallelogram makes it possible to introduce a “phase shift” of the second transmission relative to the first transmission. By deforming the parallelogram, the second transmission is driven and thus rotates the corresponding disk without the other disk rotating.

In such a device, so that tubes can be taken not only at one end of the tube but over their entire length, it is advantageously provided that:
- the first disc has a radial slot allowing the introduction of a tube from its periphery towards the center,
- the second disc has a radial slot allowing the introduction of a tube from its periphery towards the center, and
when the radial slot of the first disc coincides with the radial slot of the second disc, the holding system is in the released position.

In this embodiment, the first transmission and the second transmission can each have in the distal position two separate wheels in contact with the peripheral toothed crown. Thus, it is possible to have a drive wheel permanently engaged with each of the two disks to be driven in rotation.

The features set out in the following paragraphs may, optionally, be implemented, independently of each other or in combination with each other:

- in the second transmission, the axis of rotation of the drive wheel is connected to the axis of rotation of the first toothed wheel by at least one first connecting rod, the axis of rotation of the first toothed wheel is connected to the axis of rotation of the second toothed wheel by at least one second connecting rod, and the axis of rotation of the second toothed wheel is connected to the axis of rotation of the third toothed wheel by at least one third connecting rod, each connecting rod thus defining one side of the deformable parallelogram;

- the control means for modifying the relative position of the axis of rotation of the first toothed wheel with respect to the axis of rotation of the drive wheel comprise a cylinder, for example a hydraulic cylinder (other actuators such as a geared motor can also be envisaged);

- the motor is an electric motor;

- the holding system comprises two jaws arranged on either side of the centre of the first disc, each jaw being movable in radial translation and each jaw is associated with a control pin extending towards the second disc and the free end of which is housed in a groove formed in the second disc, said groove being shaped such that a relative rotational movement between the first disc and the second disc controls a simultaneous translational movement of the two jaws;

- the motor has an output shaft equipped with a first toothed pulley driving a second toothed pulley via a toothed belt so as to form a reducer, the drive wheel and the second toothed pulley being mounted integrally on the same shaft.

According to another aspect, there is provided a bending machine, characterized in that it comprises among other things a device for gripping a tube as described above.

Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the attached figures, in which:

Fig. 1

shows a perspective view of a gripping device according to a preferred embodiment.

Fig. 2

shows the gripping device of the in perspective from another angle of view.

Fig. 3

is a front view, called the front face, on an enlarged scale, showing the gripping device without a protective cover.

Fig. 4

is a view similar to the with some elements removed to allow visualization of the internal mechanism of the gripping device of the previous figures.

Fig. 5

shows a front view, called the front face, of the assembly illustrated on the .

Fig. 6

shows a front view, called the back face, of the assembly illustrated on the .

Fig. 7

is a cross-sectional view of the elements of Figures 4 to 6, and

Fig. 8

is a cross-sectional view of the elements of Figures 4 to 6 according to a different cutting plane.

Reference is now made to the . This figure shows a gripping device intended to be placed at the distal end of a robot arm to handle a tube of circular section in a bending machine. Other applications than tube bending can be envisaged.

This gripping device firstly comprises a first disk 2 and a second disk 4. Each of these two disks has in its center a recess 6 intended to serve as a housing for a tube not shown and at its periphery a toothed crown 8. The two disks are coaxial. In the illustrated embodiment, the first disk 2 has the same diameter as the second disk 4. The recesses 6 are preferably similar since they are intended to accommodate the same tube.

In the illustrated embodiment, which is a preferred non-limiting embodiment, a radial slot 10 extends for each of the discs from the central recess serving as a housing 6 to the toothed crown 8 which therefore has a discontinuity at its periphery. This embodiment is advantageous because it allows the gripping of a tube over the entire length of the tube. Without this radial slot (an alternative that could be envisaged) the gripping device would be limited in most configurations to the gripping of one end of the tube.

The first disk 2, or front disk, carries a device for holding a tube arranged in the housing 6. This holding device, in the illustrated embodiment, comprises two jaws 12 mounted to slide in translation in a radial direction. Each jaw 12 is mounted to slide in a rail 14. The jaws 12 can move towards or away from the center of the first disk 2. They thus make it possible to tighten or loosen a tube arranged in the housing 6. Alternatively, a holding device could have jaws that can move in a pivot and move along, for example, an arc of a circle.

The control of the movement of the jaws 12 is carried out by the second disk 4. Each jaw 12 is associated with a control pin 16. This control pin 16 extends through a radial oblong hole 18 (cf. ) to the second disk 4. The distal part of each control pin 16 is housed in an arcuate slot 20 (figures 2 and 7) designed such that when the second disk rotates relative to the first around its axis of rotation (corresponding to the axis of its toothed crown 8), the control pin 16 moves radially in the corresponding radial oblong hole 18. The radial oblong hole 18 and the arcuate slot 20 are furthermore each time such that when the two radial slots 10 are superimposed, the jaws 12 are in the released position, that is to say away from the housing 6.

We notice that the first disk 2 and the second disk 4 are mounted ( ) on a support plate 22 which is used, as will be explained later, for supporting other elements of the gripping device.

Since the center of the disks must remain free for the passage and housing of a tube, their axis of rotation is geometric and the rotational guidance of the disks is achieved by bearings 24 mounted on the second disk 4 and cooperating on one side with the support plate 22 and on the other side with the first disk 2. A groove 26 (figures 1 and 2) is made undercut at the rear of the toothed crown 8 of the first disk 2 and in the support plate 22 to receive these bearings and achieve rotational guidance.

The first disk 2 and the second disk 4 of the gripping device can pivot about their geometric axis of rotation in a synchronous manner. Such a rotational movement allows, for example, the orientation of a tube clamped between the jaws 12 of the holding system. A relative rotational movement between the first disk 2 and the second disk 4 allows the holding system to be actuated. A motor, for example an electric motor 28, as well as a cylinder, for example a hydraulic cylinder 30, are used to carry out these rotational movements. The mechanism for driving these two disks in rotation is shown in more detail in FIGS. 3 to 8.

The electric motor 28 has an output shaft 32 which is here parallel to the axis of rotation of the first disc 2 and the second disc 4. A reducer, visible only on the , is provided at the output of the electric motor 28. Thus, a first toothed pulley 34 is mounted on the output shaft 32 and cooperates with a second toothed pulley 36 by means of a toothed belt 38.

The second toothed pulley 34 is mounted on a rotation shaft and is secured to it, said shaft being called the input shaft 40. The latter also carries a pinion, called the input pinion 42, secured to the input shaft 40 and coplanar with the first disc 2.

There is a cross-sectional view passing through the first disk 2. It shows the input pinion 42 which meshes with a first pair of satellite pinions 44, each satellite pinion 44 being engaged with the first disk 2. The presence of this first pair of satellite pinions 44 makes it possible to drive the first disk 2 continuously even when passing through the radial slot 10. This pair of pinions is in fact such that the points of contact between these pinions and the first disk are spaced apart from each other by a distance greater than the width of the radial slot 10. Thus, whatever the position of the first disk 2, at least one satellite pinion 44 is engaged with this first disk 2. The electric motor 28 can then always drive the first disk 2 (and where appropriate the tube held between the jaws 12) in rotation.

We notice on the that the input pinion 42 also meshes with a third pinion, or double pinion 46. The latter transmits the rotational movement of the input pinion 42, which is only in the plane of the first disc 2 also in the plane of the second disc 4, as can be seen in the which is a cross-sectional view passing through the second disk 4. The double pinion 46 may be a pinion of double width, that is to say whose width corresponds substantially to the width of the first disk 2 increased by the width of the second disk 4 (while the input pinion 42 and the satellite pinions 44 each have a width corresponding substantially to that of the first disk 2) or it may be two separate pinions both secured to the same axis.

In the plan of the second disc 4 ( ), the double pinion 46 meshes with a fourth pinion 48 which in turn meshes with a fifth pinion 50 which then drives the second disc 4.

It is noted that the satellite pinions 44, the double pinion 46, the fourth pinion 48 and the fifth pinion 50 all have the same number of teeth. Thus, the transmission ratio between the input pinion 42 and the first disc 2 is the same as between the input pinion 42 with the second disc 4 (which has a toothed crown 8 of the same diameter and with the same number of teeth as the first disc 2). Different gears could be chosen to obtain the same transmission ratio.

It is further noted that the fifth pinion 50 is mounted on the same axis as a satellite pinion 44. However, these two pinions are not linked and can rotate on this axis independently of each other (as explained below). This mounting on a common axis makes the structure simpler and more compact.

To ensure continuous drive of the second disk 4 despite the radial slot 10 that it includes, it is planned to “double” the fifth pinion 50. The latter then drives a sixth pinion, or intermediate pinion 52, which in turn drives a seventh pinion 54, similar to the fifth pinion 50 (same diameter, same number of teeth), and meshing with the toothed crown 8 of the second disk 4.

The axes of the various pinions (input pinion 42, satellite pinions 44, fifth pinion 50, intermediate pinion 52 and seventh pinion 54) except the axes of the double pinion(s) 46 and the fourth pinion 48 are mounted on the support plate 22 and are therefore fixed (because they do not change their relative position) relative to the electric motor 28. Most of these fixed rotation axes are also also mounted on a counter-plate 56 (figures 1 and 3) and are thus held in bearings at their two ends. This counter-plate 56 also receives the bearings of the first toothed pulley 34 and the second toothed pulley 36. In the illustrated embodiment, the axis of the seventh pinion 54 is mounted on a bearing only, made in the support plate 22.

The axes of the double pinion(s) 46 and of the fourth pinion 48 are movable relative to the other pinion axes and in particular relative to the support plate 22.

As can be seen in particular in Figures 5 and 6, two first connecting rods 58 connect the input shaft 40 to the axis of the double pinion(s) 46. The length of these connecting rods is adapted to keep the double pinion 46 (or one of the double pinions 46) engaged with the input pinion 42. These first connecting rods 58 are thus located on either side of the double pinions 46.

Similarly, second connecting rods 60 connect the axis of the double pinion(s) 46 with the axis of the fourth pinion 48 and third connecting rods 62 connect the axis of the fourth pinion 48 with the (fixed) axis of the fifth pinion 50. These pairs of connecting rods 58, 60, 62 thus define three sides of a deformable parallelogram, the fourth side being formed by the segment going from the center of the input shaft 40 to the center of the axis of the fifth pinion 50, this fourth side being “rigid”.

The deformable parallelogram above can be deformed by the jack 30. The latter is pivotally mounted on the support plate 22 and acts advantageously on the axis of the fourth pinion 48. Any other point of action on the deformable parallelogram can be envisaged: the action can be direct on the parallelogram or indirect, for example using an arm acting on this parallelogram.

The operation of the gripping device is described below.

A position of the jack 30 corresponds to the position illustrated in the figures in which the jaws 12 are in the open position. Furthermore, the first disk 2 and the second disk 4 are oriented relative to the support plate 22 which also has a slot such that the two radial slots 10 (that of the first disk 2 and that of the second disk 4) overlap with the slot of the support plate 22 such that a tube can slide in the radial slots 10 and reach the center of the disks, at the level of the housings 6. In a bending machine, a device such as the gripping device illustrated in the figures is mounted at the end of a robot arm which moves to grip a tube to be bent. Due to the presence of the slots mentioned above, the gripping device can grip the tube to be bent not only at its end but all along this tube.

Once the tube is in its housings 6, the jack 30 is actuated. The double pinion 46 (or one of the double pinions 46) guided by the first connecting rods 58 turns around the input pinion 42 which remains stationary. In this movement, the pinions, from the fourth pinion 48 to the seventh pinion 54 are driven and therefore pivot the second disk 4 relative to the first disk 2. As explained above, the radial oblong holes 18, the arcuate slots 20 and the control pin 16 cooperate to close the jaws 12 on the tube to be bent. The electric motor 28 can then be started to orient the tube to be bent in space.

The jaws 12 can be released in all positions of the first disc 2 and the second disc 4. The jack 30 then acts in the opposite direction to release the tube.

These technical solutions can be applied in particular in a bending machine.

Many variations can be envisaged here. For example, for a device for gripping a tube at the end of the tube, the presence of radial slots is unnecessary and the structure can then be simplified (a single pinion engaging each peripheral toothed crown).

The electric motor here first drives the disc carrying the holding means, here formed by jaws. It could also drive the other disc first.

The presence of a reducer is optional. In addition, this reducer could be achieved by a gear train rather than with wheels and a belt.

The cylinder is a preferred solution for the opening and closing control of the device holding system. However, other actuators, even an electric motor, could be considered.

The proposed solution has a simple structure and works advantageously with a single motor. This configuration, in addition to saving on a motor, also allows for a simplification of the device's control means.

This solution is also particularly advantageous due to its flexibility of use. The fact that the clamping jaws can be controlled independently of the rotation of the gripping head makes it possible to grip and release the tube in almost any position of the tube.

This disclosure is not limited to the preferred embodiment and the variants mentioned above, only as an example, but it encompasses all the variants that may be envisaged by those skilled in the art within the framework of the protection sought.

Claims (9)

Device for gripping a tube to be bent comprising:
- a first disk (2) with a first center and a first peripheral toothed crown (8), said disk having in its center a housing (6) for a tube,
- a system (12) for holding a tube placed in the center of the first disk (2), said system being mounted on a face called the front face of said first disk (2),
- a second disk (4) with a second center and a second peripheral crown (8), mounted coaxially with the first disk (2), said disk having in its center a housing (6) for a tube,
- a control system (16, 18, 20) such that a relative rotational movement of the second disc (4) relative to the first disc (2) controls the tightening and loosening of the holding system (12),
- a motor (28) with an output shaft (32), said motor being intended for driving in rotation a disk, chosen from the first disk (2) respectively the second disk (4), by means of a first transmission (42, 44) comprising at least one toothed wheel (42), called a drive wheel,
characterized in that the gripping device further comprises:
a second transmission between said drive wheel (42) of the first transmission and the other disk, corresponding to the second disk (4) respectively to the first disk (2),
in that the second transmission comprises at least three toothed wheels (46, 48, 50) each having an axis of rotation:
- a first toothed wheel (46) meshing with the drive wheel (42) while being mounted on an axis movable relative to the axis of the drive wheel,
- a second toothed wheel (48) driven by the first toothed wheel (46) while being mounted on an axis movable relative to the axis of the drive wheel (42), and
- a third toothed wheel (50) meshing, on the one hand, with the second toothed wheel (48) and, on the other hand, directly or indirectly, with the peripheral crown (8) of the other disk (4),
the axes of rotation of the three toothed wheels and the drive wheel defining articulations of a deformable parallelogram, and
in that control means (30) are provided for modifying the relative position of the axis of rotation of the first toothed wheel (46) with respect to the axis of rotation of the drive wheel (42). Gripping device according to claim 1, characterized in that
- the first disc (2) has a radial slot (10) allowing the introduction of a tube from its periphery towards the center,
- the second disc (4) has a radial slot (10) allowing the introduction of a tube from its periphery towards the center, and
in that when the radial slot (10) of the first disc (2) coincides with the radial slot (10) of the second disc (4), the holding system (12) is in the released position. Gripping device according to claim 2, characterized in that the first transmission and the second transmission each have in the distal position two separate wheels (34; 50, 54) in contact with the peripheral toothed crown (8). Gripping device according to one of claims 1 to 3, characterized in that in the second transmission the axis of rotation of the drive wheel (42) is connected to the axis of rotation of the first toothed wheel (42) by at least one first connecting rod (58), the axis of rotation of the first toothed wheel (48) is connected to the axis of rotation of the second toothed wheel (50) by at least one second connecting rod (60), and in that the axis of rotation of the second toothed wheel (50) is connected to the axis of rotation of the third toothed wheel (52) by at least one third connecting rod (62), each connecting rod thus defining one side of the deformable parallelogram. Gripping device according to one of claims 1 to 4, characterized in that the motor is an electric motor (28). Gripping device according to one of claims 1 to 5, characterized in that the control means for modifying the relative position of the axis of rotation of the first toothed wheel (46) with respect to the axis of rotation of the drive wheel (42) comprise a jack (30), for example a hydraulic jack. Gripping device according to one of claims 1 to 6, characterized in that the holding system comprises two jaws (12) arranged on either side of the center of the first disc (2), each jaw (12) being movable in radial translation,
in that each jaw (12) is associated with a control pin (16) extending towards the second disc (4) and the free end of which is housed in a groove (20) formed in the second disc (4), said groove being shaped in such a way that a relative rotational movement between the first disc (2) and the second disc (4) controls a simultaneous translational movement of the two jaws (12). Gripping device according to one of claims 1 to 7, characterized in that the motor (28) has an output shaft (32) provided with a first toothed pulley (34) driving a second toothed pulley (36) via a toothed belt (38) so as to produce a reducer, the drive wheel (42) and the second toothed pulley (36) being mounted integrally on the same shaft (40). Bending machine, characterized in that it comprises, among other things, a device for gripping a tube according to one of claims 1 to 8.