GB2098895A - Pipe bending apparatus - Google Patents

Abstract

A pipe bending machine for non-mandrel bending of pipes includes a bend die 1 and a follower slide 3. The pipe to be bent is deformed into the follower slide only in the region of the bend die 1. In order that the tail of the pipe may extend in any desired orientation the follower slide 3 is angled with respect to the centre line A of the machine. <IMAGE>

Description

SPECIFICATION Pipe bending apparatus The present invention relates to pipe bending apparatus.

During pipe bending it is necessary to prevent collapse of the pipe in the region of the bend being formed. One method of preventing collapse is to provide a flexible mandrel within the pipe. The bending of pipes without mandrel is however also known.

In non-mandrel bending machines the pipe to be bent is clamped into a portion of circumferentially extending channel of a circular or part-circular bend die which is rotated about its axis to bend the pipe as the pipe is advanced through the machine. During this operation a follower slide in which the pipe is partially clamped as described below moves tangentially to the bend die along a line parallel to the centre line of the machine and at a speed commensurate with the rate at which the pipe moves through the machine. A force is applied to the follower slide perpendicular to its line of movement to urge the slide towards the die.

The follower slide includes a longitudinally extending channel into which a half-section of the pipe only partially seats. The channel of the bend die has a section corresponding either to a half-section of the pipe which thus seats therein, or to the channel profile of the follower slide.

The channels are shaped such that slight deformation of the pipe section will occur in the region at which the follower slide is urged towards the die and the pipe will seat in the channel once deformation has occurred. This deformation gives added strength to the pipe in the bend region thereby preventing collapse.

There is however the disadvantage that because the pipe only seats in the follower slide at the bend die and not upstream thereof there is an angle between the line of movement of the follower slide and the centre line of the pipe. The tail of the pipe is thus displaced out of line, and in fact this displacement may be so large that the pipe tail interferes with pipe positioning devices on the machine.

In order to overcome the disadvantage it is general practice to restrain this deflection by mechanical means. The forces produced however tend to bow the pipe between the bend head and the point at which it is restrained.

This bowing can interfere with the bending operation.

It is also known to perform non-mandrel bending with a follower slide which is urged towards the bend die as above but which is stationary, throughout the bending operation, which moves past the bend die at a rate slower than the pipe, or which moves past the die for a short distance and then stops. These methods have the same disadvantages as discussed above.

It is an object of the present invention to obviate or mitigate the abovementioned disadvantages.

According to a first aspect of the invention there is provided a method of bending a pipe in a pipe bending machine for bending a pipe without a mandrel, the melthod comprising bending the pipe around a bend die whilst a follower slide is urged towards the bend die by a clamping force transversely of the follower slide, said bend die and follower slide each having a channel formation receiving the pipe and which together cause deformation of the pipe section at the bend die to permit non-mandrel bending, wherein said follower slide is angled with respect to the centre line of the machine.

According to a second aspect of the invention there is provided a pipe bending machine in which a follower slide may be urged towards a bend die around which the pipe may be bent, wherein the follower slide is angled with respect to the centre line of the machine.

The method of the invention may be applied to pipe bending, in which: (a) the follower slide moves linearly past the bend die at the same rate as the pipe; (b) the follower slide moves past the bend die at a rate slower than the pipe; (c) the follower slide moves past the bend die for a certain distance and is then arrested before termination of the bending operation; and (d) the follower slide remains stationary.

The apparatus of the invention may be constructed so that it may be modified to perform bending operations with a mandrel.

The invention will be further described by way of example with reference to the accompanying drawings, in which: Figure 1 is a plan view of part of a pipe bending machine in accordance with the invention; Figure 2 is a diagrammatic sectional view of the follower slide used in the machine of Fig.

1 and showing also the pipe, and Figure 3 is diagrammatic plan illustration showing a pipe in relation to the bend die and follower slide of the machine of Fig. 1.

The pipe bending machine shown in Fig. 1 is of generally conventional construction and includes a bend die 1 mounted on a pivotally movable bend arm 2, and a follower slide 3 on a backing slide 4. A boost cylinder 5 serves to move the assembly of follower slide 3 and backing slide 4 linearly past the bend die 1. A cylinder 6 acts generally transversely to the line of movement of the follower slide 3 to urge the slide 3 towards the die 1 during a bending operation. A clamp arrangement 7 mounted on the bend arm 2 serves to clamp the pipe against the bend die 1 during bend ing.

The centre line of the pipe bending machine is depicted by "A" and the centre line of cylinder 6 by "8".

Follower slide 3 is movable at an angle a with respect to the centre line A of the machine (see also Fig. 3).

The various components of the pipe bending machine and its use will be further described with respect to the bending of circular section pipes, such as pipe 8 as shown in Figs. 2 and 3. It should however be appreciated that with suitable modification the machine may be used for bending pipes of noncircular section.

The bend die 1 has a circumferentially extending channel 9 (Fig. 3) having a section corresponding to a half-section of the pipe 8 which will thus seat therein. It is of course possible for the channel 9 to have a section corresponding to the channel of the follower slide 3 (see below).

Follower slide 3 has a longitudinally extending channel 10 having an opening of width less than the outer diameter of pipe 8 to be bent, although in some cases the width may be greater. Channel 10 is formed of two arcuate sections not on a common circular locus but each having a radius larger than the outer radius of pipe 8 to be bent. Slide 3 may be formed by machining a semi-circular channel of diameter greater to that of pipe 8 symmetrically along on the arrangement of two parallel workpieces separated by a spacer.

Once the spacer has been removed and the workpieces juxtaposed, the channel 10 is defined.

It will thus be appreciated that a halfsection of pipe 8 will not seat in channel 10.

During pipe bending discussed more fully below, deformation of the pipe into channel 10 will occur at the bend die to permit nonmandrel bending.

The bending of a pipe 8 will now be described.

Pipe 8 is firstly clamped against the bend die 1 by means of the clamp arrangement 7.

Bending is commenced by rotating bend arm 2 in the direction of arrow X and moving follower slide 3 past die 1 (as described more fully below) whilst applying a clamping force by means of cylinder 6.

At the bend die 1 the pipe 8 is deformed into the channel 10 to permit bending without a mandrel, as described previously. Because pipe 8 is deformed into channel 10 only in the region of bend die 1 there is an angle ss between the tail of pipe 8 and the line of movement of slide 3 (see Fig. 3).

It will be recalled that slide 3 moves at an angle a to the centre line of the machine. This angle (which is equal to angle ss) is generally between 1 and 5 and is preferably selected such that the centre line of the undeformed length of pipe 8 is parallel to the centre line A of the pipe bending machine, thus preventing the tail of pipe 8 from interfering with conventional pipe handling apparatus (not shown) provided upstream of the bend die 1, and off the centre line. It is however also possible for the follower slide 3 to be angled such that the pipe 8 is not brought into parallel with the centre line A but rather is located at any desired angle thereto.

The angle at which the follower slide 3 moves with respect to the centre iine A of the machine may be fixed or adjustable, i.e. the angle may be changed for the bending of different pipes.

Although the follower slide is angled with respect to centre line A it should be noted that the centre line B of cylinder 6 is maintained at right angles to centre line A so that the angle between centre line B and the line of movement of slide 3 is 90-a.

It will of course be appreciated that, in the case where the follower slide is stationary with respect to the bend die, its angled disposition slide allows the pipe 8 to remain parallel to the centre line of the apparatus, or at any other desired angle thereto.

Claims (5)

1. A method of bending a pipe in a pipe bending machine for bending a pipe without a mandrel, the method comprising bending the pipe around a bend die whilst follower slide is urged towards the bend die by a clamping force transversely to the follower slide, said bend die and follower slide each having a channel formation receiving the pipe and which together cause deformations of the pipe section at the bend die to permit non-mandrel bending, wherein said follower slide is angled with respect to the centre line of the machine.

2. A method as claimed in claim 1 wherein the follower slide is angled so that the pipe upstream of said deformation is parallel to the centre line of the machine.

3. A method as claimed in claim 1 or 2 wherein the pipe is of circular section and the channel of the follower slide is comprised of two connected arcuate sections not on a circular locus and each having a radius larger than the outer radius of the pipe to be bent.

4. A method as claimed in claim 1 or bending a pipe substantially as hereinbefore described.

5. A pipe bending machine in which a toliower silue may be urged towards a bed die around which the pipe may be bent, said bend die and follower slide each having a channel formation receiving the pipe and which together cause deformations of the pipe sections at the bend die to permit non-mandrel bending, wherein said follower slide is angled with respect to the centre line of the machine.

5. A pipe bending machine in which a follower slide may be urged towards a bend die around which the pipe may be bent, wherein the follower slide is angled with respect to the centre line of the machine.

6. A pipe bending machine substantially as hereinbefore described with rerference to the accompanying drawings.

CLAIMS (18tug 1982)