GB2101027A - Method and apparatus for flaring the end of a pipe - Google Patents

Abstract

A method and apparatus for forming a flared end on a pipe 13, in which a male die 8 is positionable over the pipe at a location adjacent to but spaced from the end of the pipe. An elastomeric bung 14 is mounted on the end of the piston rod 1 of a fluid pressure operated piston and cylinder arrangement, the rod extending through a female die 7. The end of the bung is fitted over the rod 1 and the bung and the end of the pipe abut the inner surface of the female die 7. The male die 8 surrounds and supports that portion of the pipe into which the bung has been inserted, but leaves free, on the exterior, an unsupported length. The piston and cylinder arrangement are operated so that a stop 12 urges the bung against the female die, compressing it axially, so that it expands radially and presses the unsupported portion of the pipe to provide the flared end. <IMAGE>

Description

SPECIFICATION Method and apparatus for flaring the end of a pipe The present invention relates to a method and apparatus for forming a flared end on a pipe.

It is often advantageous to form a flared end on a pipe, to enable the pipe to be connected to a similar pipe having a flared end. It is quite difficult to achieve this flared end in an economic manner, particularly if the pipe is a metal pipe lined with a plastic lining material, because the act of flaring can damage or distort the lining.

It is now proposed, according to the present invention, to provide a method of forming a flared end on a pipe, said method comprising the steps of inserting an elastomeric bung into the end of the pipe to be flared, placing a male die around the exterior of the pipe, so that the male die surrounds at least a portion of the pipe into which the bung has been inserted, but leaves free, on the exterior, an unsupported length corresponding to the length of the flare desired, and axially compressing the elastomeric bung, whereby it expands radially outwardly and flares the unsupported length of pipe.

During the axial compression of the bung, the portion of the pipe which is held within the male die is supported thereby to prevent it from expanding radially. The very end portion, however, is unsupported and so, as the bung expands radially, due to its axial compression, it urges the pipe radially outwardly to provide the flared end.

It has been indicated above that the unsupported length of the pipe corresponds to the length to be flared. In practice, this will mean that the actual unsupported length will be slightly greater than the final length which is flared, a small portion of the unsupported length remaining substantially unaffected.

Experience has shown that, in order to prevent the pipe from splitting, it is often necessary to prepare the end of the pipe to be flared, this preparation involving providing a smooth finish at the end. It can be useful, in this connection, to ensure that the end of the pipe is cut off accurately square, to provide a chamfer on the outside diameter and/or to polish the pipe end.

Preferably, the end of the pipe and the bung are abutted against the inner surface of a female die, which is shaped to correspond to the path of movement of the end of the pipe as it is flared, thereby reducing to a minimum any gap between the end of the pipe and the female die, to prevent the elastomer from being extruded therebetween. This will only be effective if the pipe is prevented from moving axially.

Preferably, therefore, the pipe is clamped adjacent the male die on the side thereof remote from the end of the pipe. This may be achieved by means of a plurality of partannular wedges which are mounted on the pipe on the side of the male die remote from the female die, the wedges having part-cylindrical inner surfaces adapted to clamp on to the exterior of the pipe and tapered external surfaces to cooperate with the tapered inner surface of a clamping ring, means being provided to draw the clamping ring towards the male die whereby the wedges are urged into clamping contact with the pipe.

The invention also provides apparatus for forming a flared end on a pipe, said apparatus comprising a male die positionable over the pipe at a location adjacent to, but spaced from, the end of the pipe, an elastomeric bung insertable into the interior of the pipe from the end, the male die surrounding at least a portion of the pipe into which the bung has been inserted, but leaving free, on the exterior, an unsupported length, and means for axially compressing the elastomeric bung, whereby it expands radially outwardly and flares the unsupported length of the pipe.

Advantageously, the apparatus further comprises a female die against which the end of the pipe and the bung may be abutted, the inner surface of the female die being shaped to correspond to the path of movement of the end of the pipe as it is flared, thereby reducing to a minimum any gap between the end of the pipe and the female die, to prevent the elastomer from being extruded therebetween.

Preferably the male die comprises a pair of semi-cylindrical die halves which are insertable into an annular die holder. A plurality of part-annular wedges may be mountable on the pipe on the side of the male die remote from the female die, the wedges having partcylindrical inner surfaces adapted to clamp onto the exterior of the pipe and tapered external surfaces to cooperate with the tapered inner surface of the clamping ring, means being provided to draw the clamping ring towards the male die, whereby the wedges are urged into clamping contact with the pipe, to prevent axial movement of the pipe.

The bung is preferably mounted on a rod, which passes axially through the female die and is retained thereon by a stop, means being provided to move the rod axially, whereby the stop compresses the bung against the female die. A fluid pressure operated piston and cylinder arrangement may be used to effect the movement of the rod which can then form the piston rod of the piston and cylinder arrangement.

In order that the present invention may more readily be understood, the following description is given, merely by way of example, reference being made to the accompanying drawing, in which: Figure 1 is a schematic cross-section through one embodiment of apparatus accord ing to the present invention in a first position; and Figure 2 is a similar view showing the apparatus in its other extreme position.

Referring to the drawings, the apparatus illustrated therein comprises a piston rod 1 which is screwthreaded at each end. At its lefthand end a saddle 2 is threaded onto the piston rod which is inserted into a hydraulic cylinder body 3 having a return spring 4.

Axially reciprocable within the cylinder body 3 is a hollow piston 5, which is provided with an internal thread at its lefthand end which cooperates with the external thread on the saddle 2.

The cylinder body 3 is secured by means (not shown) to the lefthand face of a female die holder 6 which is used to support, on the side remote from the cylinder 3, a female die 7 which is of a bowl shape having a flat, radially extending inner portion and a concave generally curved outer portion 7B.

Mountable adjacent the female die 7 is a male die 8 which is formed with two shell halves, these being provided with a radially outwardly extending shoulder 8A. This is inserted into an annular male die holder 9 having a recess to accommodate a shoulder 8A of each of the two male die halves 8.

Locatable to the right of the male die 8 and its holder 9, is a sleeve 10 which has a tapered inner surface adapted to cooperate with the tapered outer surface of two part annular wedges 11 which themselves have a part-cylindrical inner surface.

A hollow cylindrical elastomeric bung 14 is secured onto the end of the rod 1 by a locking nut 12 which is threaded onto the end of the rod.

The cylinder body 3 is provided with a hydraulic fluid inlet 1 5.

In order to use the apparatus described above, it is brought to the position illustrated in Fig. 1, that is with the cylinder body 3 mounted on the rear face of the female die holder 6. With the piston 5 in the fully retracted position illustrated in Fig. 1, the rod is connected to the piston 5 by the saddle 2.

The elastomeric bung and locking nut are mounted on the other end of the rod and the lock nut is then tightened up to lock the elastomeric bung in position against the front face of the female die.

One then takes the pipe 13 to be flared, and feeds onto this, in this order, the sleeve 10, the part annular wedges 11, the male die holder 9 and the male die halves 8. This assembly and the pipe are then presented to the female die face and the pipe is pushed over the elastomeric bung until the pipe contacts the die face. The male die holder 9 is then moved and clamped to the female die holder which brings the male die halves into contact with the female die and forms the boundary of the gap to which the pipe is to be flared.

The pipe is then clamped in place by mov ing the sleeve 10 towards the male die holder 9 by any suitable means, e.g. by threading it on until a specified torque has been reached.

The apparatus is then ready for use.

Hydraulic fluid is then pumped into inlet 15 and the piston is thus forced to the left, against the action of the spring 4, whereby the piston rod 1 also moves to the left bringing with it the locking nut or stop 12 which compresses the bung 14 axially against the face of the female die 7. The bung then expands radially outwardly and flares the pipe in the manner shown in Fig. 2. It will be appreciated that the shaping of the outer portions 7B of the female die is such that there will be substantially no gap left between the end of the pipe and the curved surface of the female die, so that the elastomer will not be extruded between the end of the pipe and the female die. If this were to happen, then the end of the pipe would simply be enveloped by the bung and no flaring would take place.

When the pipe is fully flared, this can be detected by a rapid rise in hydraulic pressure and the flaring process has been completed.

The hydraulic pressure is then released from the cylinder and the spring 4 returns the piston back to the position illustrated in Fig.

1. The male and female die holders are then separated which leaves the flared pipe with the male die halves, the male die holder, the sleeve and the wedges round the outside of the pipe. In order to dismantle these parts, the sleeve is moved away from the male die holder which unloads the wedges. Once the sleeve has cleared from the wedges, they can be removed as they only fit around half of the outside diameter of the pipe. The sleeve must remain on the pipe as this fits around the pipe until the male die and die holder are removed, this being achieved by moving the male die holder away from the pipe flare whereupon the dies can be removed radially as before.

The male die holder and the sleeve are then removed by bringing them over the flared end of the pipe. This means that the sleeve and the male die holder should each have an internal diameter which is greater than the flare to enable this to happen.

The method and apparatus of the present invention are capable of flaring any tube or pipe material and it has been found that they are quite satisfactory even for flaring the ends of pipes lined with a plastic material. It has been found, however, that there can be some advantage when trying to flare the ends of lined plastics pipes, to provide a suitable lubricant, such as oil, particularly between the male die and the lining material of the pipe. It will also be noted that in the drawings, the junction of the bore through the male die and the lefthand end face has been shown as slightly radiused. This prevents too sharp a bend being formed in the pipe at the end of the flaring, thus reducing the possibility of damaging either the pipe or any lining thereon.

Claims (11)

1. A method of forming a flared end on a pipe, said method comprising the steps of inserting an elastomeric bung into the end of the pipe to be flared, placing a male die around the exterior of the pipe, so that the male die surrounds at least a portion of the pipe into which the bung has been inserted, but leaves free, on the exterior, an unsupported length corresponding to the length of the flare desired, and axially compressing the elastomeric bung, whereby it expands radially outwardly and flares the unsupported length of pipe.

2. A method according to claim 1, wherein the end of the pipe and the bung are abutted against the inner surface of a female die, which is shaped to correspond to the path of movement of the end of the pipe as it is flared, thereby reducing to a minimum any gap between the end of the pipe and the female die, to prevent the elastomer from extruding therebetween.

3. A method according to claim 1 or 2, wherein the pipe is clamped adjacent the male die on the side thereof remote from the end of the pipe.

4. A method of forming a flared end on a pipe substantially as hereinbefore described, with reference to and as illustrated in, the accompanying drawing.

5. Apparatus for forming a flared end on a pipe, said apparatus comprising a male die positionable over the pipe at a location adjacent to, but spaced from, the end of the pipe, an elastomeric bung insertable into the interior of the pipe from the end, the male die surrounding at least a portion of the pipe into which the bung has been inserted, but leaving free, on the exterior, an unsupported length, and means for axially compressing the elastomeric bung, whereby it expands radially outwardly and flares the unsupported length of pipe.

6. Apparatus according to claim 5, and further comprising a female die against which the end of the pipe and the bung may be abutted, the inner surface of the female die being shaped to correspond to the path of movement of the end of the pipe as it is flared, thereby reducing to a minimum any gap between the end of the pipe and the female die, to prevent the elastomer from being extruded therebetween.

7. Apparatus according to claim 5 or 6, wherein the male die comprises a pair of semi-cylindrical die halves insertable into an annular die holder.

8. Apparatus according to claim 7, wherein a plurality of part-annular wedges are mountable on the pipe on the side of the male die remote from the female die, the wedges having part-cylindrical inner surfaces adapted to clamp onto the exterior of the pipe and tapered external surfaces to cooperate with the tapered inner surface of a clamping ring, means being provided to draw the clamping ring towards the male die, whereby the wedges are urged into clamping contact with the pipe.

9. Apparatus according to any one of claims 6, 7 or 8, wherein the bung is mounted on a rod, which passes axially through the female die and is retained thereon by a stop, means being provided to move the rod axially, whereby the stop compresses the bung against the female die.

10. Apparatus according to claim 9, wherein said means to move the rod axially comprise a fluid pressure operated piston and cylinder arrangement, mounted on the back of the female die, the rod forming the piston rod of said arrangement.

11. Apparatus for forming a flared end on a pipe, said apparatus being constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.