The present invention relates to a device permitting retaining a tube on a bending machine and more particularly retaining and driving said tube in the bending head.

There are known tube bending machines which comprise an elongated frame along which moves a first movable carriage secured to a gripper for holding the tube to be bent, a second carriage movable independently of the first and carrying a mandrel or mouse disposed within the tube and a bending head.

The first movable carriage comprises a gripper which grips the tube to be bent to move it in longitudinal translation and/or rotation, as a function of pre-selected positions relative to tools carried by a bending head.

For a bending operation, the first movable carriage advances and turns the tube about its longitudinal axis to position it relative to the bending tools carried by the bending head. The second movable carriage positions, within the tube and in the bending zone, the mandrel or a mouse to ensure the bending of the tube and to avoid its flattening during deformation.

Thus, gripping and bending tools coact so as to grip a forward portion of the tube in which the mandrel or mouse is not located. The gripping and bending tools are driven simultaneously in rotation about a substantially vertical axis to permit the bending of the tube. This gives rise to the curving of the tube about the bending tool.

Then, the tools are retracted, the first movable carriage is advanced to position the tube for a new bending operation, the second movable carriage is moved to withdraw the mandrel or its mouse from its position within the tube.

The assembly of the bending head comprises an assembly with a fixed arm in which is mounted the mechanism for driving in rotation the bending tool. On the stationary arm is also mounted the mechanism for actuating the pressing tool. An assembly with a swinging bending arm is mounted on the assembly with a fixed arm so as to be secured in rotation to the bending tools about the axis of these latter, and this assembly carries gripping tools and their actuating mechanism.

The machine is preferably controlled entirely automatically so as to carry out a series of bending operations on a given tube.

The drive and retaining device according to the present invention has for its object to ensure simultaneously on the one hand the movements in longitudinal translation and rotation of the tube or pipe to be bent, and on the other hand the positioning of the mandrel or the mouse within the tube or pipe to permit the bending of this latter.

The drive and retaining device according to the present invention comprises a guide mandrel secured to gripping means that will be applied against the internal wall of the tube to be bent, and movement means which are common to the mandrel and to the gripping means.

The drive and retaining device according to the present invention comprises gripping means which are connected to the movable carriage by a mandrel carrying bar.

The drive and retaining device according to the present invention comprises gripping means which are constituted by a gripper that can be deformed by hydraulic or pneumatic control means, so as to be able to exert a sufficient pressure force against the internal wall of the tube and to block this latter in the bending position.

The drive and retaining device according to the present invention comprises a gripper which is constituted by fingers that move axially to increase the external diameter of said gripper.

The drive and retaining device according to the present invention comprises a gripper which is constituted by a sealed envelope of elastomer which is elastically deformable to increase the external diameter of said gripper.

The drive and retaining device according to the present invention comprises a mandrel which is constituted by a solid bar, at one of its ends, with deformable cups ensuring the deformation of the tube during its bending.

The drive and retaining device according to the present invention comprises a mandrel whose solid bar is secured at the end opposite that carrying the cups of a gripper.

The drive and retaining device according to the present invention comprises a mandrel whose solid bar is secured, at the end opposite that carrying the cups, to a connecting bar permitting connection with a gripping member.

The description which follows with respect to the accompanying drawings, given by way of non-limiting example, will permit better understanding of the invention, the characteristics that it provides and the advantages which it is adapted to supply:

FIG. 1 is a perspective view showing a machine for bending tubes or pipes and its gripping device, according to the present invention.

FIGS. 2 to 7 are views showing different modifications of embodiments of the gripping device according to the present invention.

FIGS. 8 to 12 are views showing the different steps in the bending cycle of the bending machine provided with the gripping device according to the present invention.

There is shown in FIG. 1 a bending machine 1 comprising a fixed frame 2 which carries at one of its ends a bending head 3 about which pivots a bending arm 4.

The fixed frame 2 comprises, opposite the bending head 3 and along its longitudinal axis, a guide rail 5 on which slides the carriage 6 which moves toward and away from the bending head 3.

The carriage 6 comprises securement means 7 for the reception and securement of a bar 8, which is moved in translation and in rotation about its axis.

The bar 8 comprises, at its free end and opposite that held by the securement means 7, a gripping device 9 permitting ensuring simultaneously on the one hand movements in longitudinal translation and in rotation of a tube or pipe 10, and on the other hand the positioning of a mandrel 11 or mouse within the tube 10 to be bent.

The gripping device 9 is constituted by an internal gripping member 12 which can be integrated or not with the mandrel 11.

The bending arm 4 comprises a jaw support 14 which moves horizontally in the direction of the bending head 3.

The bending arm 4 is secured to a bending roller 14 constituting a securement device for one of the jaws 16 of a gripping jaw 15, the other jaw 17 being fixed on the jaw support 13 of the bending arm 4.

The bending head 3 can comprise movement means, to be able to move it horizontally and vertically relative to the fixed frame 2, which is to say in directions located in a plane perpendicular to that containing the longitudinal axis of the machine 1 or the fixed frame 2, which is generally defined by the tube 10 to be bent.

In FIGS. 2 and 3 there is shown the gripping device 9 according to the present invention comprising a mandrel or mouse 11 which is fixed on the mandrel carrying bar 8, so as to ensure movement and bending of the tube 10.

The mandrel 11 is constituted by a solid bar 18 terminating for example at one of its ends in a series of cups or rollers 19, mounted on an axle adapted to deform during bending of the tube 10. The cups 19 are adapted to ensure the constant deformation of the tube 10 without rupture.

The bar 18 comprises, opposite the cups 19, a gripper 12 which will bear, after opening or resilient deformation, against the internal wall of the tube 10 so as to ensure on the one hand the holding of this latter and on the other hand the horizontal and rotary movements relative to the fixed frame 2 of the bending machine 1.

The gripping member 12 is constituted by expansible means such that its external diameter will increase to press against and be gripped against the internal wall of the tube 10 to be bent.

The gripping member 12 can be deformed by hydraulic or pneumatic control means, so as to be able to exert a sufficient pressure force to block the tube 10 in the bending position.

According to this embodiment, the gripping device 9 constitutes the mandrel 11 and the gripper 12 in one piece.

In FIGS. 4 and 5, there is shown a first modification of the gripping device 9 whose mandrel 11 is separated from the gripper 12 to constitute two separate members. In this modification, the gripper 12 is disposed against the mandrel 11 to prolong the latter axially.

In FIGS. 6 and 7, there is shown a second modification of the gripping device 9 according to the present invention, whose mandrel 11 forms a member independent from the gripper 12. In this modification, the gripper 12 is connected to the mandrel 11 by a connecting bar 20.

The gripping device 9 according to the present invention permits, during the steps of bending the tube 10, ensuring simultaneously on the one hand by means of the gripping member 12 the movements in longitudinal translation and rotation of the tube 10 relative to the bending head 3, and on the other hand the positioning of the mandrel 11 within the tube 10 to permit the bending of this latter without deformation.

It will be noted that the bending machine 1 comprises a single movable carriage 6, in contrast to the prior art, reducing the time of movement and the bending cycles of the tube 10.

Because of this, the movable carriage 6 comprises a first moto reducer 21 permitting movements of this latter along the guide rail 5 of the frame 2 of the bending machine 1. The movable carriage 6 has a second moto reducer 22 ensuring the rotational movements of the bar 8 carrying the gripping device 9 and the mandrel 11.

The gripper 12 can be constituted by fingers 23 movable axially to increase the external diameter of said gripper (FIGS. 2, 5 and 6).

The gripper 12 can be constituted by a sealed envelope 24 of resiliently deformable elastomer to increase the external diameter of said gripper (FIGS. 3, 5 and 7).

In FIG. 8 there is shown the emplacement of the tube 10 in the jaws 16 and 17 of the gripping jaws 15 to carry out a first bend. The mandrel 11 is in position within the tube 10 to accompany this latter during bending whilst the gripper 12 is free, which is to say, it is not pressed against the internal wall of the tube 10.

In FIG. 9 there is shown the jaws 16 and 17 of the gripping jaws 15 in closed position against the tube 10. The gripping device 9 constituted by the mandrel 11 and the gripper 12 is in the same position and in the same condition as in FIG. 8.

In FIG. 10 there is shown the bending of the tube 10 to the radius of curvature of the bending roller 14 after pivoting of the bending arm 4 about the bending head 3. The gripping device 9 constituted by the mandrel 11 and the gripper 12 is in the same position and in the same condition as in FIG. 8. It will be noted that because of the bending of the tube 10, the latter has advanced in the direction of the bending head 3.

In FIG. 11 there is shown the end of bending of the tube 10 and the opening of the jaws 16 and 17 of the gripping jaws 15. The bending arm 4 is still in position pivoting about the bending head 3. The gripping device 9 and more particularly the gripper 12 is open or inflated to be pressed against the internal wall of the tube 10 and to grip this latter.

In FIG. 12 there is shown the longitudinal movement of the tube 10 to disengage it from the jaw 16 of the gripping jaws 15. The movement of the tube 10 is carried out by means of the movable carriage 6 which slides by means of the moto reducer 21 along the rails 5 of the frame 2 in the direction of the bending head 3. The movement of the carriage 6 gives rise simultaneously to the movement of the mandrel carrying bar 8 secured to the gripping device 9 constituted by the mandrel 11 and the gripper 12 gripped within the tube 10.

It will be noted that the gripping machine 1 comprises a movable carriage 6 common to the gripping means (12) and to the mandrel (11) of the gripping device 9 to permit the movements of the tube 10.

It should also be understood that the preceding description has been given only by way of example and that it in no way limits the scope of the invention from which one will not depart by replacing details of execution described by any other equivalent.