GB2153471A - Retaining a fitting on a pipe - Google Patents

Abstract

A male fitting (10) for example a B.S.P. fitting, is retained on the end of a pipe by deforming the end to provide a conical receiving formation (26) with which a conical projecting formation (30) of a female thread is, in use, engaged. The end (26) of the pipe (10) is deformed by a punching operation in which the end (26) is punched into a conical recess (25) of the male fitting. <IMAGE>

Description

SPECIFICATION Method of retaining a fitting on a pipe This invention relates to a method of retaining a male fitting, such as a BSP (British Standard Pipe) fitting, on the end of a pipe, such as is used to convey hydraulic fluid under pressure in a hydraulic system, to enable the pipe to be connected to another pipe or a female fitting on another pipe, or machine part having a female fitting or thread provided thereon.

For convenience, female fittings such as are provided on the ends of pipes, and machine parts having female threads for engagement with the male fitting will be called "female fittings".

Where a pipe has a thick wall, it is well established practice to roll a male thread on the exterior surface of the pipe adjacent the end thereof so that a connection may be made with a female fitting, for example on the end of another pipe. It is also well known to cut, file or mill the end edge of the pipe wall to provide a conical annular receiving formation with which a conical projecting formation of said another pipe or said female fitting having the female thread, in use, engages, to provide a fluid-tight connection between the pipes.

However, where the pipe wall is thin, i.e. less than 12 gauge (wall thickness 2.642 mm) for example, where the pressures within the pipe are not great enough to warrant a more expensive pipe with a thicker wall, there is insufficient thickness of pipe wall for rolling a thread or for the conical receiving formation to be provided. Accordingly, it is necessary for a male fitting, i.e. a fitting having a male thread on the external surface thereof to be provided at the end of the pipe. At present, this is retained by welding or brazing the male fitting to the end of the pipe, the male fitting providing a conical receiving formation to receive the conical projecting formation of said another pipe or female fitting when the female thread on said another pipe is engaged with the male thread of the male fitting.However, such a method is slow and requires the services of a skilled workman to ensure that a fluid-tight weld or braze between the male fitting and the pipe end on which it is received, is achieved.

Accordingly, it is one object of the invention to provide a new or improved method of retaining a male fitting on the end of a pipe.

According to the invention, we provide a method of retaining a male fitting on the end of a pipe comprising the steps of passing the pipe through an opening in the male fitting, so that the male fitting is received thereon, deforming the end of the pipe to prevent the fitting passing over said end.

Preferably, the opening in the male fitting terminates in a conical recess and the end of the pipe is deformed to provide a conical receiving formation which is, in use, received in the conical recess of the female fitting.

Thus a conical male projecting formation on the end of another pipe or female fitting can be engaged with the conical receiving formation at the end of the one pipe.

The male fitting may be received on the pipe with the end of the pipe adjacent said fitting, and the end of the pipe may be deformed into the conical recess to provide said conical receiving formation. Thus, the male fitting acts as a former as the end of the pipe is deformed. Alternatively, a former separate from the male fitting could be used, which would need to be suitably constructed to facilitate its removal after the end of the pipe has been deformed.

Where the male fitting is used as a former, preferably said deforming step is achieved using a punching tool having a first part with an external diameter substantially equal to or slightly greater that the internal diameter of said pipe, so that during the punching operation at least part of the pipe in the opening in the male fitting is urged outwardly into tight frictional engagement with the opening of the fitting to prevent the fitting moving along the pipe away from said end, and a second part having a conical surface which engages in the end of the pipe to urge the end of the pipe outwardly and into said conical recess of the male fitting to provide said conical receiving formation.

Such a punching operation is not only easier and faster than prior methods which involve brazing or welding, but can be carried out by a relatively unskilled workman as a fluid-tight joint is achieved by engagement of the conical receiving formation formed in the end of the one pipe, and the corresponding conical projecting formation on the end of said another pipe or female fitting, no brazing or welding being involved.

By ensuring that during the part of the pipe in which the first part of the punch is received is urged outwardly into tight frictional engagement with the opening of the male fitting, there is no risk of the male fitting passing along the pipe which, could result in the fitting becoming lost if it can pass over the opposite end of the pipe, or at least incovenience to a fitter fitting the pipe. Thus, not only is the fitting retained on the pipe by the deformed end of the pipe, but its position is fixed on the end of the pipe.

The male fitting may be conveniently provided on the end of the pipe at a location such as a factory remote from where the pipe is to be fitted.

During punching, the fitting may be held by clamp means, such as a two-part clamp, at least one of said parts being movable transversely of the longitudinal axis of the pipe into clamping engagement with the fitting.

The clamp means may include a stop, the pipe being moved prior to punching and prior to clamping, towards and into engagement with the stop so that the fitting is at a predetermined position relative to the clamping parts, to facilitate clamping.

The stop would of course need to be removed before the punching operation can be carried out.

The male fitting may comprise a body in which the opening for the pipe is provided, the opening extending along the entire length of the body and communicating with the body at both ends, and an outwaradly projecting collar integral or secured rel ative to the body around the axis of the opening, the collar providing a grip for a spanner or wrench to facilitate assembly of the male fitting with the female fitting on said another pipe. During clamping, the collar of the male fitting may be received in a hollow or hollows provided in one or both of the clamping parts.

According to a second aspect of the invention, we provide a male fitting for use in the method according to the first aspect of the invention, the fitting having a body, an elongate opening extending through the body from one end to the other, a conical recess at one end of the body, surrounding the opening and a thread formed on the external surface of the body around the axis of the opening at least adjacent said one end.

According to a third aspect of the invention, we provide a joint between one pipe and another pipe or a female fitting, said one one pipe having retained thereon a male fitting, said another pipe or female fitting having a socket part with an internal female thread provided therein with which the external male thread of the male fitting is engaged, said another pipe or female fitting having a conical male projection received in the conical receiving formation provided by said deforming step at the end of said one pipe.

The invention will now be described with the aid of the accompanying drawings, in which: Figure 1 is a side view, partially in section, showing a male fitting provided on the end of a thin-walled pipe, and a female fitting on the end of another pipe; Figures 2a to 2d show various steps which result in the deformation of an end of a thin-walled pipe and method of providing a male fitting thereon.

Referring first to Figure 1, a thin-walled pipe 10, i.e. having a tube wall of a thickness t between 2.642 mm and 0.914 mm, i.e. 12 gauge to 20 gauge, has received on an end 11 thereof, a male fitting 12. In the present case, the male fitting is a BSP fitting and has a collar 13 comprising a plurality of hexagonal faces 14 which are intended to be engaged by a spanner, wrench or the like to facilitate connecting the male fitting 12 to a female fitting as hereinafter described.

Such pipes are used in many applications, and the invention has particular, but not exclusive, application to pipes which convey hydraulic fluid under pressure in a hydraulic system.

The collar 13 is integral with a body 15 of the male fitting 12 and provided on an external surface of the male fitting 12, adjacent an end 16 thereof, is a male thread 17. The body has an opening 20 extending therethrough from end 16 to opposite end 21, the opening 20 having a diameter slightly larger than the external diameter D of the pipe 10.

The end 16 of the male fitting 12 has a conical shaped annular recess 25 and as shown in Figure 1, the end 26 of the pipe 10 has a conical annular receiving formation 26 in engagement with the surface 25 which, in use, receives a conical annular projecting formation 30 on the end of another pipe 31, for example another pipe in a hydraulic system, on which a female fitting 32 is provided, which female fitting 32 has a female thread 33 to co-operate with the male thread 17 on the male fitting 12.

The female fitting 32 is provided on the end of the pipe 31 in any desired manner.

In place of the female fitting 32 on the end of the pipe 31, if desired a pipe of larger diameter than pipe 10 could be provided, so that the male thread 17 on the male fitting 12 engages with a female thread provided in the interior of the larger diameter bore pipe.

Instead of a collar 13 of hexagonal configuration on male fitting 12, a knurled collar or a collar of other configuration could be provided to engage any desired tool, or if desired, the collar 13 may be omitted altogether.

Thus the fitting 12 may not be of the exact configuration as shown, but any desired male fitting having a through opening 20 to receive the pipe 10 could be provided. Preferably, the opening 20 is of constant diameter from the conical recess 25 to the other end 21 of the fitting 12 for a reason hereinafter explained.

Referring now to Figure 2a, the first stage in a method of providing the male fitting 12 on the end of pipe 10 is shown. The pipe 10 is moved in the direction of the longitudinal axis A in the direction of the arrow until the then undeformed end indicated at 26a engages a stop 35 of a clamp means which is in its path.

The fitting 12 is received over the end of the pipe 10 prior to moving the pipe 10 or when the stop 35 is removed, and placed in a position where the pipe 10 projects a short distance from the end 16 of the fitting. Thus, when the end 16 is deformed, as hereinafter explained, the end 26a will lie adjacent end 16 of the male fitting 12.

On the right hand side of Figure 2a, a first clamping part 36 of the clamping means is shown engaged with the collar 13 of the male fitting 12 and with the pipe 10 as shown in region 10'. The part 36 has a hollow 37 in which the projecting collar 13 is received. On the left hand side of Figure 2a, a second clamping part 38 which also has a hollow 39 to receive the collar 13, is shown displaced laterally from the pipe 10 and fitting 12.

The first clamping part 36 has already been moved into engagement with the pipe 10 and the male fitting 12, and the second clamping part 38 is about to be moved transversely relative to the axis A of the pipe 10 into engagement with the pipe, the male fitting 12 and the other clamping part 36.

Also shown in Figure 2a is a punching tool 40 which is hereinafter described in more detail.

Referring now to Figure 2b, the second clamping part 38 has been moved transversely relative to axis A, into engagement with the pipe 10 and the male fitting 12 and the first clamping part 36, so that the male fitting 12 is firmly clamped by the clamping parts 36 and 38 and held rigidly relative thereto. Further, the pipe 10 is held rigidly by the clamping parts 36, 38 which are shaped to surround the pipe 10 in the region 10'.

The clamping parts 36 and 38 may comprise part of an automated machine. In any case, only a small portion of the clamping means is seen in the drawings.

The stop 35 is, in Figure 2b, about to be removed. It will be appreciated that as the pipe 10 and male fitting 12 are rigidly held by the clamping means that the stop 35 is no longer required and if retained in position, would prevent operation of the punching tool 40.

The punching tool 40 has a first part 41 having a diameter D' substantially equal to, or slightly greater than, the internal diameter D" of the pipe 10 and sufficient length L to enable the first part 41 to be inserted within the pipe 10 so that the first part 41 extends along substantially the entire length of the opening 20 provided in the male fitting.

The end of part 41 is tapered to facilitate its insertion into the end of the pipe 10 as hereinafter explained.

The punching tool 40 has a second part 43 which comprises a conical surface 44 which extends at an angle relative to axis A substantially equal to the angle of the conical surface on the conical recess 25 of the male fitting 12.

Referring now to Figure 2c, a further stage in the operation is shown. The stop 35 has been removed, and the punching tool 40 has been inserted partially into the end of pipe 10.

Because the external diameter D' of the first punch part 41 is slightly greater than the internal diameter D" of the pipe 10, the wall of the pipe 10 will be urged outwardly into tight frictional engagement with the opening 20 provided in the male fitting 12 so that the position of the fitting 12 along pipe 10 will be fixed.

Referring now to Figure 2d, a further stage in the operation is shown. The second part 43 of the punching tool 40 is received within the end of the pipe 10 and as shown, the end 26 of the pipe 10 is urged outwardly by che surface 44 into engagement with the conical recess 25 of the male fitting 12 so as to extend at an angle to axis A substantially equal to the angle of the conical surface 44 of the second punch part 43, and the conical surface of the conical recess 25 of the male fitting 12.

Thus, the fitting 12 will be retained on the pipe 10 as the fitting will not be able to pass over the deformed end 26 even if the frictional engagement between the pipe 10 and the fitting 12 is overcome.

The first part 41 of the punching tool 40 is received within the pipe 10 along substantially the entire length of the opening 20 of the male fitting and thus along substantially the entire part of the pipe which is received within the male fitting 12 between the end 21 thereof and the deformed end 26.

Subsequent to the stage shown in Figure 2d, the punching tool 40 is removed by moving along axis A out of the pipe 10, and the clamping parts 36 and 38 are both moved transversely to axis A to release the pipe 10 and male fitting 12 from engagement.

The pipe 10 and male fitting 12 will then be ready for engagement with a female fitting, such as shown at 32 in Figure 1, on the end of another pipe, or the male fitting 12 may be received within the end of a larger diameter pipe as required.

It will be appreciated that the method described enables a male fitting 12 to be easily and conveniently retained on the end of a thin-walled pipe. It is envisaged that the method described may be used for pipes having a wall thickness from 12 gauge to 20 gauge and thus the necessity for welding or brazing to retain male fittings on pipes as in prior known methods is entirely alleviated.

Various modifications may be made in the method described, and the apparatus for carrying out the method, without departing from the scope of the invention.

For example, it is not necessary to provide the deformed end 26 of the pipe 10 by using a punching tool such as that shown at 40, but any alternative tool or means for providing deformation may be used.

Where a punching tool is used, this may be substantially different from the punching tool described, although preferably has a conical surface 44 to urge the end 26 of the pipe 10 outwardly. For example, the punch need not have a first punching part to urge the pipe outwardly into engagement with the wall of the opening where a friction fit between the male fitting 12 and the pipe 10 to prevent the male fitting moving along the length of the pipe, is not required.

Although in the method described, the conical recess 25 of the male fitting 12 has been used as a former during the punching operation, if desired a separate former could be used. In this event the former would need to be construction so as to be removable after the punching operation and the position of the male fitting would be fixed as frictional engagement between the male fitting and the pipe could not be achieved as described during punching. Hence the method described above is preferred.

Although as described, the male fitting 10 is for connection to a female fitting or female thread on another pipe, of course, the male fitting can be connected to any female fitting, for example to a female threaded machine part, such as a valve or actuator. In this latter case, the female threaded part may not have a conical projecting portion which is received in the conical receiving formation 25 of the end 26 of the pipe 10 but alternative means would need to be provided if a fluid tight joint is required.

Claims (15)

1. A method of retaining a male fitting on the end of a pipe comprising the steps of passing the pipe through an opening in the male fitting, so that the male fitting is received thereon, deforming the end of the pipe to prevent the fitting passing over said end.

2. A method according to Claim 1 wherein the opening in the male fitting terminates in a conical recesses and the end of the pipe is deformed to provide a conical receiving formation which is, in use, received in the conical recess of the female fitting.

3. A method according to Claim 2 wherein the male fitting is received on the pipe with the end of the pipe adjacent said fitting, and the end of the pipe is deformed into the conical recess to provide said conical receiving formation.

4. A method according to Claim 3 wherein said deforming step is achieved using a punching tool having a first part with an external diameter substantially equal tc or slightly greater than the internal diameter of said pipe, so that during the punching operation at least part of the pipe in the opening in the male fitting is urged outwardly into tight frictional engagement with the opening of the fitting to prevent the fitting moving along the pipe away from said end, and a second part having a conical surface which engages in the end of the pipe to urge the end of the pipe outwardly and into said conical recess of the male fitting to provide said conical receiving formation.

5. A method according to Claim 4 wherein during punching, the fitting is held by clamp means.

6. A method according to Claim 5 wherein the clamp means comprises a two-part clamp, at least one of said parts being movable transversely of the longitudinal axis of the pipe into clamping engagement with the fitting.

7. A method according to Claim 5 or Claim 6 wherein the clamp means includes a stop, the pipe being moved prior to punching and prior to clamping, towards and into engagement with the stop so that the fitting is at a predetermined position relative to the clamping parts.

8. A method according to any one of the preceding claims wherein the male fitting comprise a body in which the opening for the pipe is provided, the opening extending along the entire length of the body and communicating with the body at both ends, and an outwardly projecting collar integral or secured relative to the body around the axis of the opening, the collar providing a grip for a spanner or wrench to facilitate assembly of the male fitting with the female fitting on said another pipe.

9. A method according to Claim 8 where appendant to Claim 6 or Claim 7 wherein during clamping, the collar of the male fitting is received in a hollow or hollows provided in one or both of the clamping parts.

10. A method substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

11. A male fitting for use in the method according to any one of Claims 1 to 10 the fitting having a body, an elongate opening extending through the body from one end to the other, a conical recess at one end of the body, surrounding the opening and a thread formed on the external surface of the body around the axis of the opening at least adjacent said one end.

12. A male pipe fitting for use in a method according to any one of Claims 1 to 10 substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

13. A joint between one pipe and another pipe or a female fitting, said one one pipe having retained thereon a male fitting according to Claim 11 or Claim 12 by a method according to any one of Claims 1 to 10, said another pipe or female fitting having a socket part with an internal female thread provided therein with which the external male thread of the male fitting is engaged, said another pipe or female fitting having a conical male projection received in the conical receiving formation provided by said deforming step at the end of said one pipe.

14. A joint between one pipe and another pipe or a female fitting as hereinbefore described with reference to and as shown in the accompanying drawings.

15. Any novel feature or novel combination of features disclosed herein and/or shown in the accompanying drawings.