GB2187666A - Pipe bending apparatus - Google Patents

Abstract

A pipe-bending apparatus 1 comprises a pivotable bend arm 2, upper and lower bend dies 3 (and 4 not shown) mounted on the arm 2 on a common vertical axis, clamping means 5, 6, also mounted on the arm for clamping a pipe P in the respective die, and follower slides 8 and 9 of channel-shaped configuration respectively associated with the dies 3 and 4 for engagement with the pipe. The slides 8 and 9 may be advanced independently of each other so that, during bending at the larger radius die 3, slide 9 need not be advanced thereby avoiding any possibility of interference with clamp 6. <IMAGE>

Description

SPECIFICATION Pipe bending apparatus The present invention relates to apparatus for the bending of metal tubes and other elongate stock, i.e.

so-called pipe-bending apparatus.

Apparatus for the draw bending of pipes, tubes and the like is well known. Generally, such apparatus comprisesacarriageorthe like for advancing the pipe along the centre line ofthe apparatus, a pivotal bend arm, a bend die and a pipe clamp both mounted on the bend arm, and a follower slide. To effect bending, the pipe is firstly advanced by the carriage so thatthe portion ofthe pipe to be bent is in the region ofthe bend die, and advancement ofthe carriage is terminated. Atthis stage, the bend arm extends transversely to the follower slide. The clamp is moved along the bend arm to clamp the pipe in the die, and the follower slide is applied against the pipe.

Bending now commences by pivotally moving the bend arm so as to rotate the bend die. During this pivotal movement ofthe bend arm,the pipe clamp is moved therewith. Simultaneously, the follower slide is moved tangentiallyto the bend die and the bend is produced. During this bending, the pipe (and thus the carriage) is "pulled" along the centre line ofthe apparatus.

Such apparatus may be of the 'shift-head' type which incorporates a plurality (usually two) of bend dies (usually of different radii) positioned one above the other on the same vertical axis. In a shift-head machine, the pipe to be bent is positioned along either an upper or lower centre line (the two centre lines being in the same vertical plane) depending on which ofthe dies isto be used. The term 'shift-head' is derived from the fact that the dies of the apparatus may be moved (or shifted) laterally of the machine centre line sothatthe required die engagesthe pipe on the centre-line of the machine.

The 'shift-head' apparatus has upper and lower clamps each mounted on the bend arm and each serving to clamp the pipe in one ofthe bend dies.

Similarly, the follower slide ofthe apparatus comprises a plurality of channeled blocks orthe like (one of each of the bend dies) mounted on a common slide so that both blocksareadvanced at the same speed during bending (irrespective of which die is used).

We have howeverfound that problems arise in the case where the dies are used for producing bends of significantly different radii.

When bending is effected atthe larger radius die, the channeled block associated with the smaller radius die may interfere with the pipe clamp associated with the smaller radius die. The problem arises because the channeled blockforthe smaller die necessarily projects laterally beyond thatforthe larger radius die by a significant distance and, similarly, the pipe clamp forthe smaller radius die projects laterally beyond thatforthe larger radius die. When bending is effected atthe larger radius die, thefollowerslide arrangement must be advanced more quicklythan when bending is effected atthe lower radius die, whereas the angular speed of the bend arm is similar (orthe same) in both cases.As a result, the channeled blockforthe smaller radius die is advanced relatively quickly towards the clamp for the smaller radius die and may ultimately make contact therewith, which is obviously undesirable.

It is an object of the present invention to obviate or mitigate this disadvantage.

According to the present invention there is provided pipe-bending apparatus comprising a bend arm, upper and lower bend dies mounted on the arm on a common vertical axis, clamping means for clamping a pipe in the dies, and a followerslide associated with each of the dies wherein the slides may be advanced independently of each other.

The invention is particularly applicable to a shift-head bending machine with a plurality(e.g.2) of dies of significantly different bend radii in which the pipe clampforthe smaller radius die projects laterally beyond thatforthe larger radius die, and the followerslideforthe smaller radius die projects laterally beyond thatforthe larger radius die.

During bending at the larger radius die, the followersilde associated with the smallerradius die need not be adva nced, thereby avoiding any possibility of interference with the pipe clamp forthe smaller radius die.

The invention will be further described by way of example onlywith reference to the accompanying drawings, in which: Figure lisa perspective view of one embodiment of pipe-bending apparatus in accordance with the invention; Figure2 is a detail ofthe bend die arrangement of the apparatus of Figure 1; Figure3is a detail ofthe follower slide arrangement ofthe apparatus of Figure 1 as viewed in the direction of arrowA; and Figure 4 is a diagram of a hydraulic control circuit.

The apparatus 1 illustrated in Figure 1 is a so-called shift-head bending machine. The apparatus comprises a pivotal bend arm 2 on which are mounted (on a common-vertical axis) upper and lower bend dies 3 and 4 of different radii (see Figure 2 - die 3 being of a larger bend radius than die 4), upper and lower clamps 5 and 6 (mounted on the arm 2), andafollowerslidearrangement7to be described in more detail below.

As is well known for shift-head bending machines, bending is effected along either an upper centre line (as illustrated in Figure 1 forthe larger radius die 3) or along a lower centre line (forthe die 4), the upperand lower centre lines being in the same vertical plane.

To caterfor bending along vertically spaced centre-lines the pipe P may be moved vertically (a rrows X). Provision for this movement is provided in carriage C which is used for positioning the pipe for the bending operation. The term shift-head derives from the fact that, to change from bending at one die to the other, the head of the machine (i.e. that part incorporating the dies 3 and 4) is laterally shifted so that as the pipe is changed from one centre lineto the other it is engaged by the appropriate die.

The follower slide arrangement incorporates upper and lower channeled blocks 8 and 9 which are associated with the upper and lower dies 3 and 4 respectively. To caterforthe fact that lower die 4 is of smaller radius than upper die 3, the block 9 projects laterally beyond block 8. Similarly, pipe clamp 6 (for the smaller radius die 4) projects beyond clamp 5.

Referring backnowto Figure 1,the pipe P is shown as located in the larger radius die 3 and the bend arm 2 is in the 'start' position for a bending operation, although the clamp 5 and channeled block 8 have not yet been engaged with the pipe. It will be seen that if (as in the prior art apparatus) the channeled blocks 8 and 9 can only be advanced as a single unit, there is the possibility that block 9 may interfere with clamp 6 (assuming thatthe linear advancement of blocks 8 and 9 is greaterthan the 'angular' speed of clamp 6 as is likelyto be the case for bending atthe larger radius die).

To avoid this problem, and in accordance with the invention,the blocks 8 and 9 provide independently movablefollowerslidesforthe apparatus.

Movement of slide 9 is effected by a fluid pressure (e.g. hydraulic) cylinder 10 whereas movement of slide 8 is effected by a furtherfluid pressure operated cylinder 11.

Consequently, during bending atthe larger radius die 3, slide 9 need not be advanced thereby avoiding any possibility of interferencewith clamp 6.

Figure 3 shows a detail of the follower slide arrangement 7. Cylinders 10 and 11 (which are hidden in Figure 3) are mounted on a support head 12 which is itself moveable laterally ofthe machine centre line (along a slideway7a) bya further cylinder 13 so as to allowtheslides 8 and 9to be moved towards and away from the dies 3 and 4. Although cylinders 10 and 11 are hidden in Figure 3, their rods are illustrated therein as 10' and 11' respectively.

Support 12 incorporates a central channel 14 extending parallel to the machine centre line. Slide 9 is mounted on a plate 15 which is moveable along a face 12a support head and which isattachedtoa bracket 16 which locates in channel 14. Bracket 16 is, in turn, attached to the rod 10' of cylinder 10. Thus extension or retraction of cylinder 10 effects corresponding linear movement of bracket 16, plate 15 and thus slide 9. Asmall block 17 (overwhich slide 9 is moveable) serves as a guideforthe movement of plate 15.

Afurther bracket 18 is attached to the rod 1 of cylinder 11 and is fast with the follower slide 8. Thus, extension and retraction of cylinder 11 causes movement of slide 8 relative to slide 9. Slide 8 has an upper guide recess 19 in which locates a guide element 20 fixed on support head 12. Additionally, affixed to the base offollowerslide8 is a guide bar21 which slides in a channel 22 in the upper surface of follower slide 9.

As mentioned above, followerslides 8 and 9 are independently movable and, additionally, the accurate linear movement required of theses slides is ensured by the guide components described above.

The operation of cylinders 10 and 11 may be governed by conventional hydraulic control valves and a suitable arrangement is illustrated in Figure 4.

Figure 4 is self explanatory and no further explanation will be given save to say that, upon extension of either cylinder 10 or 11, hydraulicfluid passes from that cylinder to a line Lwhich is common to both cylinders. Thus, during extension of, say, cylinder 10 to move slide 9, a back pressure is established in cylinder 11 thus ensuring thatthe follower slide 8 remains stationary is not subject to unwanted movement with slide 9.

Although the invention has been illustrated with specific reference to dies 3 and 4 of different radii,the use of independently moveable follower slides is equally applicable inthe case of dies with thesame radii as such an arrangement may be required for certain bending operations.

Claims (10)

1. Pipe-bending apparatus comprising a bend arm, upper and lower bend dies mounted on the arm on a common vertical axis, clamping means for clamping a pipe in the dies, and a follower slide associated with each of the dies wherein the slides may be advanced independently of each other.

2. Apparatus as claimed in claim 1,which is a shift head bending apparatus having a plurality of dies of different bend radii, said apparatus having pipe clamps for each of the dies with the clamp for the smaller radius die projecting beyond thatforthe larger radius die, andthefollowerslideforthe smaller radius die projecting laterallybeyondthatfor the larger radius die.

3. Apparatus as claimed in claim 2, wherein the larger bend radius die is the upper die.

4. Apparatus as claimed in any one of claims 1 to 3, wherein each follower slide is associated with a respective fluid pressure operated cylinder for effecting said independent linear movement.

5. Apparatus as claimed in claim 4, wherein said fluid pressure operated cylinders are operated bya fluid pressure supply arrangement adapted to generate a back pressure in one of said cylinders when the other cylinder is being extended to advance the associated follower slide.

6. Apparatus as claimed in claim 4 or 5, wherein the cylinders and the follower slides are mounted on a support unit which is movable laterallyofthe centre line ofthe apparatus.

7. Apparatus as claimed in claim 6, wherein the support unit has a channel extending parallel to the centre line of the apparatus and a first one of said follower slides is connected to its associated cylinder by means which move along said channel during extension and retraction of this cylinder.

8. Apparatus as claimed in claim 7, wherein said firstfollowerslide is guided in its linear movement byaguideelementoverwhichtheslide movesand which is fixed relative to the support unit.

9. Apparatus as claimed in claim 7 or 8, wherein the other of said slides has a guide barwhich is slidablein a channel provided in the first said slide.

10. Pipe bending apparatus substantially as hereinbefore described with reference to the accompanying drawings.