EP0320408B1 - Control device for the reglet of a tube-bending machine - Google Patents

Abstract

This device controls, during the operational cycle of the machine, the transverse movement of a reglet (12) which is applied laterally against the tube to be bent (4) which is held and moved longitudinally by a carriage (2). A first actuator (18) moves the reglet (12) over a significant extent so as to disengage entirely the tube (4) from its clamping position and to thus enable the free passage of the carriage (2). A second actuator (23) moves the reglet (12) over a short extent, such that the tube (4) is laterally free but remains held by a portion (A) of the reglet (12). <IMAGE>

Description

The present invention relates to machines for bending tubes, and it relates, more particularly, to a control device for the strip of a machine for bending tubes. Such a device according to the preamble of claim 1 is known from document US-A-4063441.

In such a machine, the bending tool usually comprises: a rotary forming roller, of vertical axis, having at its periphery an annular groove and supporting a first jaw - a second jaw carried by a bending arm mounted pivoting around the vertical axis mentioned above, the second jaw cooperating with the first jaw to grip and drive the tube to be bent - a horizontal strip, parallel to the non-bent part of the tube, located behind the jaws and intended to be applied laterally against the tube to bend.

Thus, to produce an elbow on a part of the tube, this part is clamped between the two jaws and driven forward by the rotation of the bending arm, so as to wind in the groove of the forming roller. The angle of rotation of the arm determines the bending angle, and the radius of the forming roller determines the radius of the elbow formed on the tube. The strip, applied laterally against the tube behind the part being bent, avoids any unwanted deformation of the tube outside the part to be bent, and it transmits to the frame of the machine the forces developed in the tube during bending.

The strip is movable relative to the frame, transverse to the initial direction of the tube to be bent, so as to release this tube to allow its introduction, its advance and its withdrawal. In some machines, this strip can also be moved longitudinally to follow the advance of the tube during bending. These well-known provisions are visible, for example, in documents US-A-4063441 and GB-A-2098895.

More particularly, the aforementioned documents indicate, as control means for the displacement of the strip transversely to the initial direction of the tube to be bent, motorized means in the form of a jack, capable of tightening the strip against the tube to be bent or to move away from this tube so as to release it. In addition, these documents show screw means for adjusting the position of the strip, these means being of the manual type and not being able to intervene during an automatic operating cycle of the bending machine.

Always considering the automatic tube bending machines, in particular according to the aforementioned document US-A-4063441, the tube to be bent is pinched, in its rectilinear part, by a clamping mandrel carried by a carriage movable in longitudinal direction. The carriage controls the advance of the tube and ensures, in its stopped positions, the positioning of the tube relative to the bending tool, for the production of successive bends on this tube.

When the carriage reaches the vicinity of the bending tool, the strip constitutes by its presence an obstacle to the passage of the carriage, and it must then be retracted laterally to allow free passage of the carriage, which is achievable by means of the aforementioned cylinder . There is, however, no drawback because the tube is held by the clamp of the carriage in its part close to the bending tool.

On the other hand, when the carriage remains distant from the bending tool, the tube has a portion of considerable length which, when the strip deviates from it, is no longer supported by this strip, and is in door-to-door position. false. To then support the straight part of the tube, it is necessary to use devices. To this end, mobile supports are provided in particular distributed over the length of the machine frame and controlled either mechanically by the advance of the carriage, or by pneumatic or other means; these supports, supporting the tube at several points, retract one after the other as the carriage advances.

Such a set of supports, with their control means, constitutes a complicated, expensive and not very rational device; in particular, the adjustment of the device is inconvenient because it requires intervention on each of the supports.

The present invention aims to avoid these drawbacks, by providing a tube support device which is simple, compact, rational and easy to use, the proposed device eliminating all the supports previously mentioned, while solving the problem posed by the arrival of the carriage in interference with the strip.

To this end, the subject of the invention is a control device for a strip for a machine for bending tubes of the type considered here, which comprises, for controlling the movement of the strip during the operating cycle of the machine and transversely to the initial direction of the tube to be bent, motorized means for moving this strip over a relatively large stroke, so as to completely release the tube from its clamping position and thus allow the carriage to pass freely, this device being characterized in what it also includes other motorized means, distinct from the previous ones, for moving said strip during the operating cycle of the machine and transversely to the initial direction of the tube to be bent exclusively over a relatively short stroke, so that the tube is released laterally but remains supported by a part of the strip.

Thus, by an appropriate motorized control, the strip itself provides support for the tube to be bent as long as the carriage remains away from the bending tool. It is only when the carriage interferes with the strip that the latter is spaced apart sufficiently to completely release the tube and allow the carriage to pass.

According to a preferred embodiment of the invention, the motorized means for moving the slide over a relatively large stroke are constituted by a first cylinder, and the motorized means for moving the slide over a relatively short stroke are constituted by a second cylinder, the two cylinders being mounted "in series" and being controlled one independently of the other.

In a particular embodiment, the first cylinder, with a relatively large stroke, connects the support of the strip, which is slidably mounted on guide means carried by the frame of the machine, with the piston of the second cylinder, with relatively stroke weak, whose body is fixed to the machine frame. When the second cylinder is actuated, the strip is thus moved over a short stroke through the first cylinder which, not being actuated, then simply plays the role of a transmission rod.

The device also advantageously comprises means for manual adjustment of the relative axial position of the first cylinder and of the piston of the second cylinder. These adjustment means may take the form of an adjustment screw, mounted to rotate freely in the piston of the second cylinder along the axis of the latter and linked to a flywheel or to a crank, the screw cooperating by its threading with a socket. tapped slidingly mounted in axial direction in the piston of the second cylinder but immobilized in rotation, and fixed to one end of the first cylinder. With these adjustment means it becomes possible to compensate for any differences in thickness of the strip, without disturbing the operation of the two cylinders.

• Figure 1 est une vue en en plan par dessus, très schématique, d'une machine à cintrer les tubes avec une réglette commandée par le dispositif selon un mode de réalisation de l'invention, la réglette étant ici montrée en position de serrage du tube à cintrer;
• Figure 2 est une vue similaire à figure 1, mais montrant la réglette dans une position légèrement écartée du tube;
• Figure 3 est une vue similaire aux deux figures précédentes, montrant la réglette déplacée de manière à permettre le libre passage du chariot;
• Figure 4 est une vue de détail, avec coupe longitudinale partielle, du dispositif de commande de la réglette.

In any case, the invention will be better understood with the aid of the description which follows, with reference to the diagrammatic drawing representing, by way of nonlimiting example, an embodiment of this control device for a machine strip bending the tubes, and illustrating its operation:

• Figure 1 is a plan view from above, very schematic, of a machine for bending tubes with a strip controlled by the device according to an embodiment of the invention, the strip being here shown in the tube clamping position to bend;
• Figure 2 is a view similar to Figure 1, but showing the strip in a position slightly away from the tube;
• Figure 3 is a view similar to the previous two figures, showing the strip moved so as to allow the free passage of the cart;
• Figure 4 is a detail view, with partial longitudinal section, of the control device of the strip.

The machine for bending tubes, shown in the drawing and more particularly in Figures 1 to 3, comprises an elongated frame 1 which supports longitudinal guides along which a carriage 2 can be moved. The carriage 2 comprises a clamping mandrel 3, suitable pinching the bending tube 4 while maintaining it along a horizontal axis 5; the carriage 2 allows not only the advancement of the tube 4 along the axis 5, but also the rotation of this tube 4 around said axis 5.

At the front of the frame 1 of the machine, there is provided a bending tool which mainly comprises: a forming roller 6 of vertical axis 7, having at its periphery an annular groove 8 and supporting a first jaw 9 - a second jaw 10 carried by a bending arm 11 mounted pivoting about the vertical axis 7 - a strip 12 extending parallel to the axis 5 of the tube to be bent 4 and having a longitudinal groove 13.

The carriage 2 makes it possible to bring, to the level of the tool previously described, the part of the tube 4 which must be bent. This part of the tube 4 is clamped between the two jaws 9 and 10, and the bending arm 11 is rotated about the vertical axis 7, at a predetermined angle, to wind the considered part of the tube 4 around the forming roller. 6, by engaging it in the annular groove 8 of the roller 6.

During the bending operation, the strip 12 must be applied laterally against the tube 4, just behind the part to be bent, so as to balance the force generated by the bending torque. Clamped against the tube 4 during bending, this strip 12 must obviously be removed from the tube 4 to allow the introduction of this tube 4, its advance along the axis 5 and its withdrawal. To this end, a motorized control device is provided, which moves the strip 12 in a horizontal plane, in a direction transverse to the initial direction of the tube to be bent 4, in other words in a direction perpendicular to the axis 5 of this tube 4. The present invention relates, precisely, to the structure of this motorized control device for the strip 12, which appears in detail in FIG. 4.

The strip 12 is carried by a support 14, itself mounted on a movable horizontal slide 15 which slides on a fixed slide 16 mounted on the frame 1 of the machine, as indicated by an arrow 17.

A first control cylinder 18, arranged along an axis horizontal 19 perpendicular to the axis 5 of the tube to be bent 4, has a body 20 linked to the support 14 of the strip 12. The rod 21 of this first cylinder 17 is axially linked to the piston 22 of a second control cylinder 23, the body 24 of which is fixed to the frame 1 by means of a support 25.

The first cylinder 18, supplied with pressurized fluid at 26, has a relatively large stroke, which will be specified below by describing the operation of the machine. The second cylinder 23 has a short stroke, for example of a few millimeters, which is designated by C and whose role will also be specified below. This latter jack 23 is supplied with pressurized fluid at two locations independently of the first jack 18, as indicated by the respective arrows 27 and 28, for controlling its two movements, namely the advance and the reverse on the stroke C.

The device shown in Figure 4 further comprises manual adjustment means, with an outer crank 29 secured to an adjustment screw 30, rotatably mounted in the piston 22 of the second cylinder 23, along the axis 19 of this cylinder. The adjusting screw 30 has a smooth part mounted to rotate freely in the piston 22, but axially linked to this piston 22. The thread of the screw 30 is screwed into a threaded sleeve 31, partially housed in a central recess of the piston 22. The sleeve 31 is itself slidably mounted relative to the body 24 and to the piston 22 of the jack 23. A key 32 prevents rotation of the bush 31 relative to the body 24 of the jack 23. A connecting member, such as a screw 33, secures the sleeve 31 with the outer end of the rod 21 of the first cylinder 18. There is also provided a handle 34 secured to a pressure screw 35, which can be pressed laterally on the adjusting screw 30 to block it in rotation.

During the operating cycle of the bending machine, and more particularly in the case of the production of several bends distributed over the length of a tube 4, the strip 12 is controlled as follows by the device described above:

As long as the carriage 2 remains away from the bending tool, the strip 12 is only slightly apart from the tube 4 to allow the latter to advance between two successive bending operations. To this end, only the second cylinder 23 is actuated, and this cylinder 23 moves the slide 12 through the first cylinder 18 which then acts as a simple transmission rod. Due to the short stroke C of the second cylinder 23, the strip 12 releases the tube 4 while leaving it engaged partially in the longitudinal groove 13 of this strip 12, as shown in Figure 2 and the dashed line in Figure 4 (left). The tube 4 thus remains supported by a part of the strip 12, as indicated in A.

When the carriage 2 reaches the vicinity of the bending tool and interferes with the strip 12, it is the first cylinder 18 which is actuated so as to transversely move the strip 12 over a large stroke, as illustrated in the figure 3. The carriage 2 with its mandrel 3 can then come up to the height of the bending tool, without encountering any obstacle.

The program controlling the movements of the machine automatically determines the intervention of the first cylinder 18 or of the second cylinder 23, as a function of the position of the carriage 2.

The adjustment means 29 to 35 make it possible to correct the position of the strip 12, relative to the tube 4, in particular to compensate for any differences in thickness of this strip 12. By turning the crank 29 in one direction or the other, the sleeve 30 is moved relative to the piston 22 of the second cylinder 23, and it is thus possible to slightly shift the initial position of the first cylinder 18, of the support 14 and of the strip 12. It is understood that this adjustment has no influence on the stroke C of the second cylinder 23.

In all the preceding description, only the transverse displacement of the strip 12, which is directly concerned with the present invention, has been considered. It should be noted that this invention is applicable both to a machine with a strip only movable transversely, as to a machine with strip movable transversely and also longitudinally to accompany the tube in its advance during bending, thanks to an additional longitudinal slide 36 (see Figure 4).

As is obvious, and as appears from the above, the invention is not limited to the only embodiment of this control device for a strip for bending machines which has been described above, for exemple; on the contrary, it embraces all of the variant embodiments and applications respecting the same principle. In particular, the jacks 18 and 23 can be replaced by other motorized control means, ensuring the same functions vis-à-vis the strip in the operating cycle of the bending machine.

Claims (5)

1. A device for controlling the guide strip of a pipe bending machine, provided to be applied laterally against a pipe (4) to be bent behind the portion being bent, this pipe being held and moved longitudinally by a carriage (2), the device including, for controlling the movement of the guide strip (12) during the operating cycle of the machine and transversely of the initial direction (5) of the pipe (4) to be bent, motorised means (18) to move this guide strip (12) over a relatively long distance, so as entirely to disengage the pipe (4) from its gripped position and thus to allow the free passage of the carriage (2), characterised in that the device also includes other motorised means (23), separate from the aforementioned motorised means (18), for moving said guide strip (12) during the operating cycle of the machine and transversely to the initial direction (5) of the pipe (4) to be bent exclusively over a relatively short path (C), such that the pipe (4) is freed laterally, but remains supported by a portion (A) of the guide strip (12).

2. A control device for the guide strip of a pipe bending machine according to Claim 1, characterised in that the motorised means for moving the guide strip (12) over a relatively long path are constituted by a first jack (18), and in that the motorised means for moving the guide strip (12) exclusively over a relatively short path (C) are constituted by a second jack (23), the two jacks (18, 23) being mounted "in series" and being controlled independently of one another.

3. A control device for the guide strip of a pipe bending machine according to Claim 2, characterised in that the first jack (18), having a relatively long travel, connects the support (14) of the guide strip (12), which is slidably mounted on guide means (16) carried by the frame (1) of the machine, with the piston (22) of the second jack (23) having a relatively short travel (C), of which the body (24) is fixed (at 25) to the frame (1) of the machine.

4. A control device for the guide strip of a pipe bending machine according to Claim 3, characterised in that it also includes means (29 to 35) for manually regulating the relative axial position of the first jack (18) and of the piston (22) of the second jack (23).

5. A control device for the guide strip of the pipe bending machine according to Claim 4, characterised in that the regulating means are made in the form of a regulating screw (30), freely rotatably mounted in the piston (22) of the second jack (23) along the axis (19) of this latter and connected to a hand-wheel or a crank (29), the screw (30) cooperating by its thread with a threaded sleeve (31) slidably mounted in an axial direction in the piston (22) of the second jack (23), but rotationally immobilised and fixed (at 33) to one end of the rod (21) of the first jack (18).

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