GB2050219A

GB2050219A - Apparatus for bending pipe

Info

Publication number: GB2050219A
Application number: GB8016778A
Authority: GB
Original assignee: Siekmann GmbH
Current assignee: Siekmann GmbH
Priority date: 1979-05-22
Filing date: 1980-05-21
Publication date: 1981-01-07
Also published as: DE2920623C2; FR2457137A1; IT1140928B; GB2050219B; IT8021559A0; FR2457137B1; BE883133A; DE2920623A1; AT368723B; ATA266580A

Abstract

In a pipe bending apparatus in which a pipe length 4 is forced by a ram 5 over a curved mandrel 1 having a thickened end, a curved holding arm 2 supports the thickened end of the mandrel and receives the pipe bend. To enable bends of more than about 110 DEG to be formed, the arm 2 disengagably engages the thickened mandrel end to enable the holding arm to be swung round on a turntable 38, after release of a rightward clamping load applied to a turntable support carriage 26 to forceably engage the arm with the mandrel, whereby the pipe bend 6 can be drawn off the support arm in the reverse direction. In the rotated position of the turntable, a further support arm 40 engages and supports the mandrel when the rightward clamping load is restored. <IMAGE>

Description

SPECIFICATION Apparatus for bending pipes The invention relates to an apparatus for bending pipes.

A known apparatus for bending pipes has a curved mandrel which becomes thicker towards its end and which is detachably secured to a frame of the apparatus, and a holding arm is provided which is curved in accordance with the mandrel and which forms a rigid extension of the mandrel. The holding arm is likewise secured to the frame of the apparatus at its end opposite the mandrel, the transverse extent of the holding arm being smaller than that of the mandrel at its thickest part. To bend pipe, pipe is forced along the mandrel from its thinner end, the pipe bend passing onto the supporting arm which supports the mandrel against the pipe bending forces which tend to straighten the mandrel.The support of the mandrel by the holding arm, against its high operating loads, is quite successful in practice but the arrangement has the disadvantage that the pipe bends which can be achieved are limited to little more than 90 , i.e. up to a maximum of about 110', because the finished pipe bend must be withdrawn from the holding arm over the holding arm, which operation requires that a free space be left between the end of the holding arm and the mandrel which exceeds the length of the pipe bend.

In practice there is a great interest in being able to produce pipe bends turning through an angle substantially greater than 90 C, and particularly pipe bends turning through 1 80' plus, so that end regions of the bends extending beyond 1 80' are presented for finishing work such as the transverse cutting off of the end and/or for forming a straight welding end and so on.

It is an object of the invention therefore to provide an apparatus for bending pipes to form pipe bends turning through an angle considerably greater than 90 .

According to the invention, apparatus for bending pipes comprises a curved mandrel thickened towards one end and a curved holding arm therefor, the holding arm extending through a circular arc exceeding 110', the thickened end of the mandrel and one end of the holding arm being adapted disengagably to engage one another to enable the holding arm to support the mandrel against straightening during a pipe bending operation, and to receive the pipe bend, the holding arm being movably supported in relation to a frame of the apparatus and being movable to disengage the mandrel end for the removal of the pipe from the holding arm.

In the apparatus of the invention, the holding arm is lengthened so that it can receive pipe bends with a length going considerably beyond 90 . In contrast to the previously known apparatus, the holding arm is not permanently connected to the end of the mandrel but is disengagably engaged with it so that it is possible to release the holding arm from the mandrel, in the operation of the apparatus to enable pipe bends produced to be removed from the holding arm. Despite its being releasable, it has been found that such a holding arm can still be effective in supporting the mandrel, which is nevertheless, heavily stressed mechanically and possibly also thermally. Also economic working is possible since pipe bends can be pressed over the mandrel, and released, in relatively brief succession.

Since the length of the holding arm is no longer limited by the necessity to provide removal space for the pipe bends and is limited only by the approach of its opposite end towards the pipe fed to the mandrel, lengths of pipe bend going far beyond 180 can be produced and so all important requirements can be covered.

Specific embodiments of the invention will now be described by way of example, and not by way of limitation, with reference to the accompanying drawings in which: Figure 1 is a side view of part of an apparatus of the invention for bending pipes, Figure 2 is a section on the line lI-lI in Fig.

1, Figure 3 is a side view of part of a further apparatus of the invention, Figure 4 is a side view of a part of a still further apparatus of the invention, Figure 5 is a partial view in the direction of arrow V in Fig. 4, Figure 6 is a side view of part of a still further apparatus of the invention, and Figure 7 is a partial view in the direction of arrow VII in Fig. 6.

With reference now to the accompanying drawings in the side views according to Figs.

1, 3, 4 and 6, there is shown a mandrel 1 and a holding arm 2. The mandrel 1 is held by a straight mandrel rod 3 and, starting from this, it follows a curved course and becomes thicker, which, in detail, causes the complex shaping operations to achieve a steadily curved pipe bend with an even wall thickness from a cylindrical pipe. Lengths of pipe 4 are stored on the mandrel rod 3 and are advanced along the mandrel rod 3 by means of a ram 5 (see Figs. 3, 4 and 6) which presses them round the mandrel 1 to obtain a pipe bend 6.

In previously known pipe-bending apparatuses of this kind, a holding arm is integrally connected to the mandrel. The course of the work, during which the pipe bend leaving the mandrel first slides on the holding arm and, after the release of a holding-arm support from the apparatus, can be withdrawn in a circular movement in the same direction over the end of the holding arm, requires a considerable free bend region behind the end of the holding arm for the removal of the pipe bend.

This leads to the restriction that, conventionally, such pipe bends can only be produced with a bend limited to little more than 90 .

The maximum bend, for technical reasons, capable of being produced with such an apparatus is about 110', and this applies equally to the total angle of turn of the mandrel and the holding arm.

As Figs. 1, 3, 4 and 6 of the drawing show, the holding arm 2 of the present apparatus, and the finished pipe bend 6, turn far beyond 110 , and even beyond 180 . This means that now pipe bends can be manufactured which comprise a semi-circular section and, in addition, an end region which is available for a final machining operation, such as the facing of the end and also straightening for welding to a straight pipe for example. A limitation of the length of the holding arm and of the angle of turn of the pipe bend results, on extension beyond the forms illustrated, only in the abutment of the pipe end against the mandrel rod 3 or a pipe length 4, and, if necessary, it only requires simple constructional means to form the end support of the holding arm so that this does not restrict the bending of the pipe.As can be seen, the pipe bend can now no longer be withdrawn over the end of the holding arm in conventional manner because then it would abut against the mandrel 1 or the mandrel rod 3. The removal of the finished pipe bend 6 from the holding arm 2 is rendered possible by the fact that the holding arm 2 is constructed for release from the mandrel in a simple manner.

The mandrel 1 and the holding arm 2 are connected to one another by means of a hooking engagement, indicated at 7, wherein the holding arm offers a pressure surface 8 to the mandrel, which is directed substantially towards the centre of curvature 9 of the mandrel. This pressure surface 8 allows forces acting through the holding arm 2 towards the centre of curvature 9 to be transmitted to the mandrel 1, to counteract its loading. The loading of the mandrel during the shaping of straight lengths of pipe into pipe bends leads obviously to a tendency to bend the mandrel straight. High mandrel loading is typical of those apparatuses which are used in particular for making thick-walled, sharply bent pipe bends.In many applications, in addition to heavy loading, the pipes have to be shaped hot, in which case considerable inroad into the strength of the mandrel is made by the heat transmitted thereto.

The conventional holding arm has already proved very important in counteracting this loading. Now, however, it has been found that the transmission of bending moment between the holding arm and the mandrel is not necessarily important; a force transmission acting inwardly is usually adequately effective.

This force transmission is effected through the pressure surface 8.

Security against unintentional displacement of the holding arm 2 relative to the mandrel 1 is provided by a hooked profile 10 of the pressure surface 8 which, in the case illustrated, is of an S-shape. According to the illustration, the S-shaped profile extends in the direction of the mandrel axis i.e. along the curvature of the mandrel. There is no hooking engagement transverse to the plane of curvature of the mandrel. This renders possible a lateral outward movement of the holding arm 2, as will be explained below. It will be understood that, fundamentally, hooking engagement could also be provided in the direction transverse to the plane of curvature of the mandrel.

The release of the hooking engagement at 7 is preferably effected by a movement of the surface 8 outwardly with respect to the centre 9 and upwardly with respect to the apparatus.

The holding arm is afforded the necessary play inside the pipe bend 6 as a result of the fact that it has a smaller cross-sectional diameter than the end of the mandrel 1 and, therefore, the diameter of the internal crosssection of the pipe bend 6. Particularly important is the play between pipe bend 6 and holding arm 2 at the outside of the latter, since this is sufficient to facilitate the release of the holding arm at. its hooking engagement at 7, towards the outside of the bend.

In the arrangement of the mandrel 1 and the holding arm 2 shown in the working position in Fig. 1, the latter is held at its free end 11 only in an eye 12 of a pull strap 13, the pull strap 13 being part of a supporting member 14. The latter consists essentially of a roller carriage 15 with rollers 16, 17 which are supported on the lengths of pipe 4 guided along the mandrel rod 3. In its direction of movement parallel to the mandrel rod 3, the roller carriage 15 is held by a piston rod 18 of an adjusting jack (not illustrated) actuated by a pressure medium.

Through the piston rod 18, a tensile force can be applied to the roller carriage 14 and so to the holding arm 2, to hold this in the position illustrated and also to provide the supporting force for the mandrel 1 directed towards the centre of curvature 9.

If the piston rod 18 frees the roller carriage for movement towards the holding arm 2, however, then the latter can be lifted out of the pull strap 1 3 and can be removed, with the pipe bend 6, from the mandrel 1. Then the holding arm 2 can be taken out of the pipe bend 6 and re-positioned for a further pipe bending operation.

The roller carriage 15 is supplemented, for guiding in relation to the lengths of pipe 4, by a counter carriage 19 which likewise has two rollers 20, 21 for rolling contact at the under side of the pipe lengths 4. A connection between the carriages 15 and 19 is established by means of a claw 22, which is slidingly adjustable in height, in relation to the lower carriage 19, by means of a threaded anchoring bolt 23, so that the spacing between the rollers 16 and 17 on the one hand and 20 and 21 on the other hand is variable, to accommodate different diameters of pipe 4.

In comparison with the embodiment of Figs. 1 and 2, the embodiments illustrated in the further figures differ essentially in the manner of the support of the holding arm 2, the latter remaining connected to the supporting member in the course of operation.

In the embodiment shown in Fig. 3, the holding arm 2 is held by a supporting member 25 which again comprises a roller carriage 26 which is supported on the lengths of pipe 4 through rollers 27, 28. The roller carriage 26 is supported for adjustment in height in relation to a bracket 27 fixed to the apparatus by a vertical strut system 28, and an interposed sliding bearing 29 renders possible a horizontal movement of the roller carriage 26.

The horizontal displacement is effected by a piston rod 30 of a hydraulic or pneumatic jack (not illustrated). During the bending operation, the jack applies the holding force needed for the mandrel 1, this being transmitted by the holding arm 2, and subsequently causes the holding arm to disengage and be released from its hooking engagement with the mandrel at 7, by advancing the roller carriage 26 towards the left in Fig. 3.

A roller bearing arrangement 31, with rollers 32 and 33, which is adjustable in height and which is likewise disposed on the bracket 27, serves to support the pipes 4 and hence the mandrel rod 3.

The securing of the holding arm 2 in relation to the supporting member 25 is effected through a pivot bearing 34 having a vertical pivot axis, which is disposed centrally in relation to the end portion of the holding arm 2 received in the bearing. This pivot bearing 34 renders possible a pivoting of the holding arm out of the plane of the drawing about its end held in the pivot bearing 34. After its release from its hooking engagement at 7 by a slight advance of the roller carriage 26 towards the left, the holding arm 2 can be pivoted, with the pipe bend present on it, out of the poisition shown in Fig. 3.Then the pipe bend 6 can be withdrawn from the holding arm 2 in a counterclockwise direction and the holding arm then restored to its working position illustrated by pivoting it back and then tightening its hooking engagement with the mandrel by operating the jack to displace the carriage 26 to the right in the Figure. The apparatus is then ready for the next bending operation.

The pivoting operation of the holding arm 2 can be carried out mechanically, and, to this end, a jack 35, actuated by pressure medium and disposed on the roller carriage 26, acts through a piston rod 36 constructed in the form of a rack, to engage peripheral teeth on the pivot bearing.

Illustrated in Figs. 4 and 5 is a further embodiment which, apart from the fundamental form of the mandrel 1 and the holding arm 2, also employs the roller carriage shown in Fig. 3 with a supporting member 37 for the holding arm 2. Here, however, the holding arm 2 is anchored at its end on a turntable 38, the axis of rotation of which is again directed vertically, as at 39, but at a position spaced apart from the end portion of the holding arm 2. Upon rotary movement of the turntable 38, the holding arm 2, as a whole, moves out of the plane of curvature of the mandrel 1 represented by the plane of the drawing.

It is of particular interest, using this kind of pivoting, that a second holding arm 40 can thus be pivoted into the plane of curvature of the mandrel 1 for hooking engagement with it. As can be seen in more detail from Fig. 5, the holding arm 40 is disposed at an angle of 90 with respect to the holding arm 2. A pivoting backwards and forwards of the turntable 38 enables the two holding arms 2 and 40 to be brought alternately into operative engagement with the end of the mandrel 1, to receive a pipe bend, while the holding arm which is disengaged by the same movement is presented for the removal of the pipe bend formed around it. In this fashion, working time for the removal of the pipe bends from the apparatus is eliminated, with the result that the productivity of the apparatus is increased.This feature is particularly advantageous for the hot shaping of pipes since it enables extra delays and intervals to be eliminated.

The pivoting of the turntable 38 is effected by mechanical means, for which purpose a jack 41 actuated by a pressure medium is disposed on the roller carriage 26, the jack being aligned eccentrically with respect to the axis 39, and being provided with a piston rod 42 constructed in the form of a rack which engages with peripheral teeth 43 (see Fig. 5) on the turntable 38.

The embodiment illustrated in Figs. 6 and 7 differs from that described with reference to Figs. 3 to 5 essentially again in the form of the supporting member 44, the roller carriage 26 again corresponding to that previously described. In this embodiment, the holding arm 2 is secured to a carrier 45 which is slidably movable in a sliding bearing 46, transverse to the plane of curvature of the mandrel 1. The transverse displacement of the holding arm 2 is effected by a jack disposed at the under side of the carrier 45. Disposed parallel to the holding arm 2, on the sliding carrier 45, is a second holding arm 47 which can come into engagement with the mandrel 1 alternately with the holding arm 2 as the carrier is displaced to-and-fro by the jack.

Thus, assurance is again provided that no loss of time occurs for the removal of the finished pipe bends 6 from the holding arms 2 and 47.

Using an apparatus as described with reference to the accompanying drawings, pipe bends, if necessary, extending through more than an angle of 1 80' can be produced in a simple and rapid manner. Since the mandrel and the holding arm are detachably connected to one another, the possibility results of using two or more holding arms in alternate or successive co-operation with one mandrel so achieving a rapid working sequence. On the other hand, by using a uniform construction to effect the hooking engagement, a number of mandrels such as 1 can be combined with the same holding arm or a set of holding arms, so that less holding arms need be stocked. Also, the production cost of the mandrels is reduced because the integral arrangement of holding arm is eliminated in favour of a hooking engagement with a separate holding arm.

For the easier removal of a pipe bend from the holding arm, in the embodiments described, particularly in the embodiments using a plurality of holding arms like those described with reference to and as shown in Figs. 4 to 7, an easy detachability of the holding arm 2 from the supporting member is an advantage, particularly with heavy pipe bends which fit the supporting arm tightly.

The removal of the pipe bend can then be effected remote from the apparatus with easier accessibility and also with auxiliary equipment if necessary.

Furthermore, there is the possibility of providing the holding arm 2 with at least one cooling passage for cooling medium, which preferably extends in its neutral plane of bending stress. For example, the holding arm may be provided with a channel at both sides, which extends round the holding arm near its end having hooking engagement with the mandrel. In this channel, a cooling pipe can be inserted to supply a cooling fluid flow along one side and a return flow along the other side, the pipe having connections for coolant disposed adjacent the supporting member.

Claims

1. Apparatus for bending pipes comprising a curved mandrel thickened towards one end and a curved holding arm therefor, the holding arm extending through a circular arc exceeding 110', the thickened end of the mandrel and one end of the holding arm being adapted disengagably to engage one another to enable the holding arm to support the mandrel against straightening during a pipe bending operation, and to receive the pipe bend, the holding arm being movably supported in relation to a frame of the apparatus and being movable to disengage the mandrel end for the removal of the pipe from the holding arm.

2. Apparatus as claimed in Claim 1 in which said one end of the holding arm presents a hooked surface which is directed substantially towards the centre of curvature of the mandrel for engaging and supporting the thickened end of the mandrel and which comes out of engagement with the thickened end of the mandrel when the holding arm is moved to move the hooked surface away from the centre of curvature of the mandrel.

3. A apparatus as claimed in Claim 2 in which said one end of the holding arm has a cross-sectional diameter less than that of the thickened end of the mandrel and said hooked surface is positioned to engage and support the thickened end of the mandrel such that the holding arm is movable within a pipe bend formed on the mandrel to disengage the mandrel.

4. Apparatus as claimed in Claim 2 or 3 in which said hooked surface has an S-shaped profile which extends in the direction of the mandrel axis, said surface being substantially plane in directions transverse to the plane of curvature of the mandrel.

5. A apparatus as claimed in any one of Claims 1 to 4 in which the holding arm is connected, at its end opposite said one end thereof, to a travelling supporting member of the apparatus, which supports the holding arm at least in the direction to support the mandrel against straightening during a pipe bending operation and which is movable to move the holding arm to disengage the mandrel end for the removal of the pipe bend from the holding arm.

6. Apparatus as claimed in Claim 5 in which a pivot bearing pivotally supports the opposite end of the holding arm for swinging movement of the holding arm to carry said one end thereof away from the mandrel.

7. Apparatus as claimed in Claim 6 in which the holding arm is connected to the supporting member through a turntable that carries at least one further holding arm supported by a pivot bearing and which can be brought into operative engagement with the mandrel upon rotation of the turntable.

8. A apparatus as claimed in Claim 5 in which a sliding bearing slidably supports the oposite end of the holding arm for transverse movement of the holding arm relative to the mandrel.

9. Apparatus as claimed in Claim 5 in which a sliding carrier supports the opposite end of the holding arm for transverse movement of the holding arm relative to the mandrel and the sliding carrier carries at least one further holding arm which can be brought into operative engagement with the mandrel by movement of the carrier.

10. Apparatus as claimed in any one of Claims 6 to 9 in which a drive element is disposed on the supporting member for moving the holding arm.

11. Apparatus as claimed in any of Claims 5 to 10 further comprising a mandrel rod which supports the mandrel at its end opposite its thickened end and which receives pipe to be bent, and a ram operable to press pipe along the rod and on to and along the mandrel, the travelling supporting member being constructed in the form of a roller carriage to rest with its rollers on pipe mounted on the mandrel rod and means to hold the carriage and to move the carriage to-and-fro in the longitudinal direction of the mandrel rod.

12. Apparatus as claimed in Claim 11 in which a spacing adjustment is provided to adjust the spacing of the rollers of the roller carriage away from the longitudinal axis of the mandrel rod.

13. Apparatus as claimed in any one of Claims 5 to 11 in which the holding arm is detachably connected to the travelling supporting member.

14. Apparatus as claimed in any preceding claim in which the holding arm has means for cooling same.

15. Apparatus for bending pipes substantially as hereinbefore described with reference to, and as shown in Figs. 1 and 2 or Fig. 3 or Figs. 4 and 5 or Figs. 6 and 7 of the accompanying drawings.