Abstract:
A bending machine that includes a device that is used to drive and support a tube that is to be bent in relation to a bending head which is disposed at one end of a frame of the bending machine. The device includes a mandrel member that is solidly connected to an expandable member that is selectively applied against an inner wall of the tube to be bent and movement means that is used to align the mandrel member relative to a section of the tube to be bent during a bending step and that moves the expandable member to move the tube in translation and/or rotation between bending steps and when the expandable member is expanded to engage the inner wall of the tube.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to device for retaining a tube on a bending machine and more particularly to a device for selectively retaining or moving the tube relative to a bending head of the machine. 
   2. Brief Description of the Related Art 
   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. 
   After the tube is bent, the tools are retracted, the first movable carriage is advanced to position the tube for a new bending operation and 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. 
   SUMMARY OF THE INVENTION 
   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 present invention comprises gripping means which are connected to a movable carriage by way of a bar that also supports a mandrel. 
   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. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     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. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   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 an end retained by the securement means  7 , a gripping device  9  that is operable to function as a releasable connector to engage a tube or pipe prior to and after bending in order to permit movements in longitudinal translation and in rotation of the tube of pipe  10  and to disengage the tube or pipe to permit the positioning of a mandrel  11  or mouse within the tube or pipe  10  to be bent and wherein the movements of the tube or pipe and the mandrel are under a common drive source. 
   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 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 or rollers  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 , the gripping member  12  to function as a releasable connector such that, when expanded into engagement with the tube, the carriage  6  may be used to control the movements in longitudinal translation and rotation of the tube  10  prior to and after bending relative to the bending head  3 , and when the gripping member is not expanded, the carriage may be used to control the positioning of the mandrel  11  within the tube  10  prior to bending so as to permit the bending of the tube 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  is provided with a first gear or motor reducer  21  that permits movements of of the carriage along the guide rail  5  of the frame  2  of the bending machine  1 . The movable carriage  6  has a second gear or motor reducer  22  that controls 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 , the longitudinal movement of the tube  10  is shown to disengage it from the jaw  16  of the gripping jaws  15  when the gripper  12  is expanded to grip the tube. The movement of the tube  10  is carried out by means of the movable carriage  6  which slides, by means of the gear of motor reducer  21 , along the rails  5  of the frame  2  in the direction of the bending head  3 . Thus, the movement of the carriage  6  gives rise simultaneously to the movement of the carrying bar  8  that is secured to the gripping device  9  and thus to by the mandrel and the griper  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.