GB2095597A

GB2095597A - Expanding solder rings in pipe fittings

Info

Publication number: GB2095597A
Application number: GB8109791A
Authority: GB
Original assignee: Tryang Jig & Gauge Co Ltd
Current assignee: Tryang Jig & Gauge Co Ltd
Priority date: 1981-03-28
Filing date: 1981-03-28
Publication date: 1982-10-06
Also published as: GB2095597B

Abstract

A gapped or gapless ring of solder (11) carried on a mandrel (32) is introduced into a pipe fitting (10) and the mandrel is temporarily expanded to engage the solder ring in a recess (14) in the internal surface of the pipe fitting. The ring is further expanded in a rolling operation between rolls (23, 25). <IMAGE>

Description

SPECIFICATION Process for providing solder ring in pipe fitting and apparatus for use in the method Description of Invention A first aspect of the present invention relates to a process for providing a ring of solder in a pipe fitting. Pipe fittings are used in plumbing systems for connecting a length of pipe to one or more further lengths of pipe, to valves and other devices and to close the end of a length of pipe. The invention is concerned particularly with fittings of the kind which are soldered to the length of pipe, the required amount of solder being provided in the fitting during manufacture thereof. The invention also relates to apparatus for use in the process.

Pipe fittings for use in plumbing systems generally have relatively thin walls. When an end portion of a pipe is introduced into the fitting, there should be between the pipe and the wall of the fitting a gap which is sufficiently narrow for molten solder to spread substantially throughout the gap by capillary action. Accordingly, the soldering provided in the fitting during manufacture must not protrude substantially into the space within the fitting which is to receive the end portion of the pipe. The solder is therefore provided in a groove formed in the internal surface of the wall of the fitting by displacing material in an annular region of the wall radially outwardly to form an annular rib on the outside of the fitting.

For many years, the required quantity of solder has been provided in pipe fittings by introducing the solder in a molten condition through a feeding head which is temporarily placed within the fitting. Molten solder which is injected through the feeding head substantially fills a space between the feeding head and a wall of the fitting. It is difficult to avoid the solder intruding on the space within the fitting which is to receive an end portion of the pipe when the fitting is used, particularly as the molten or partly molten solder tends to follow the feeding head when this is withdrawn from the fitting. Other problems which are well known to those skilled in the art arise in the known process.

According to a first aspect of the present invention, there is provided a process in which a ring of solder is supported on a radially expandible mandrel at a position inside a pipe fitting, the mandrel is expanded to expand radially the ring sufficiently for axial movement of the ring relative to the fitting to be restrained, the mandrel then contracts and relative axial movement of the mandrel and fitting is effected to withdraw the mandrel from the fitting.

After the mandrel has been withdrawn from the fitting, a roller may be introduced into the fitting to roll the solder ring against an internal surface of the fitting, thereby increasing the internal diameter of the solder ring.

Throughout a process in accordance with the present invention, the ring of solder can remain in a solid condition and heating of the solder is not necessary.

As introduced into the fitting, the ring of solder may have an interruption, having been formed by bending into a curve an extruded length of solder. Immediately after expansion of the mandrel, the solder ring will usually have between its ends a gap. By subsequent rolling of the solder ring, this gap may be closed to provide a substantially endless ring.

The expression "ring" as used herein refers to a complete, endless ring, to a ring having ends between which there is no substantial gap and to a ring having ends between which there is a substantial gap.

According to a further aspect of the invention, there is provided apparatus for use in a process according to the first aspect and comprising a radially expandible mandrel and means for expanding the mandrel, the mandrel having a first abutment for limiting movement along the mandrel of the solder ring when placed on the mandrel and a second abutment for limiting movement along the mandrel of the pipe fitting when placed on the mandrel.

An example of a process embodying the invention and using apparatus in accordance with the invention, will now be described, with reference to the accompanying drawings, wherein: Figure 1 illustrates diagrammatically the combination of a pipe fitting, a ring of solder and apparatus for expanding the ring to engage loosely in the fitting; and Figure 2 illustrates diagrammatically the combination of a pipe fitting, a ring of solder loosely engaged in the fitting and apparatus for expanding the solder ring within the fitting, in both figures the fitting and the ring being shown in cross-section and the apparatus being shown partly in cross-section.

The particular examples of apparatus illustrated in the accompanying drawings are intended for use with a pipe fitting 10 which is a straight coupler and which is required to have two rings of solder 11 and 12. The fitting comprises a generally cylindrical wall 13 formed of copper. There is formed at the internal surface of the wall 13 at positions spaced from the ends of the wall by a distance approximately equal to one quarter of the length of the fitting respective annular grooves 14, 15, there being corresponding annular ribs on the external surface of the wall 13.

By means of the apparatus shown in Fig. 1, the solder rings 11 and 12 are loosely engaged in respective ones of the grooves 14 and 15 so that the rings are restrained against axial movement relative to the wall 13. The rings 11 and 12 are formed by bending extruded lengths of solder. By means of the apparatus illustrated in Fig. 2, the internal diameters of the rings are increased and the rings are formed into substantially endless rings within the grooves of the fitting.

The apparatus shown in Fig. 1 comprises a base 30, only a part of which is shown, having an aperture in which there is seated a hollow mandrel 31. The mandrel is formed of a resiliently deformable material, preferably a plastics material. A suitable material is a Nylon. An upper part 32 of the mandrel is radially expandible. To this end, there are formed in the upper part 32 a number, typically five, slits 33 which are spaced apart circumferentially of the mandrel and extend from an upper, free end of the mandrel to a level somewhat above the seat provided by the base 30. In its unstressed state, the upper part 32 of the mandrel has a substantially cylindrical form.

For expanding the upper part 32 of the mandrel radially, there is provided a plug 34 of frusto-conical form having a maximum diameter somewhat greater than the internal diameter of the upper part 32 when in its unstressed state. The plug rests in the upper end of the mandrel with its narrower end lowermost. At a position below the mandrel 31, there is mounted on the base 30 actuating means which may be in the form of a piston and cylinder unit 35. The piston of this unit is connected with the plug 34 by a substantially inextensible force-transmitting element 36 in the form of a metal rod to which the plug 34 is rigidly secured.

On the outside of the upper mandrel part 32, there is provided a first abutment in the form of an annular shoulder 37 which faces towards the upper end of the mandrel. Adjacent to the lower ends of the slits 33, there is formed on the mandrel a second abutment, also in the form of a radially outwardly projecting shoulder 38. The upper part 32 of the mandrel, which lies above the shoulder 38, has a diameter somewhat less than the internal diameter of the fitting 10. The part of the mandrel lying below the shoulder 38 has a diameter somewhat greater than the internal diameter of the fitting.

As shown in Fig. 1, a pre-formed ring of solder is placed over the upper part of the mandrel 31 to rest on the shoulder 37. The fitting 10 is then placed over the upper part of the mandrel to rest on the shoulder 38.

The shoulders 37 and 38 are spaced along an axis of the mandrel by a distance such that when the fitting rests on the shoulder 38, the solder ring resting on the shoulder 37 lies opposite to one of the grooves of the fitting.

The upper part 32 of the mandrel is then expanded by means of the piston and cylinder unit 35 and plug 34 so that the diameter of the solder ring is increased and a radially outer part of the ring engages in the groove of the fitting 10. The mandrel may be expanded until it engages the internal surface of the fitting around the entire circumference of the mandrel. The plug 34 is then moved upwardly by the piston and cylinder unit 35 and the upper part 32 of the mandrel, which has been stressed resiliently by the action of the plug, contracts as it returns to a substantially unstressed condition. The fitting 10, with the solder ring loosely engaged in a groove thereof, is then removed from the apparatus of Fig. 1, inverted and replaced over the mandrel 31 with the solder ring at a lower level than the vacant groove of the fitting.The process is then repeated with a further solder ring to engage that further ring loosely in the upper groove.

It will be noted that the axially movable plug 34 does not engages the solder rings and that no axial movement of the mandrel relative to the fitting 10 occurs during radial expansion of the solder ring. During radial expansion of the solder ring by means of the apparatus of Fig. 1, the cross-sectional dimensions of the ring are not significantly changed.

Accordingly, a gap 16 is opened up between ends of each ring. It will be noted that, when loosely engaged in the grooves of the fitting 10, the solder rings protrude considerably into the cylindrical spaced defined by the wall 13 of the fitting.

The fitting 10 with the two solder rings 11 and 12 loosely engaged therein are transferred from the apparatus of Fig. 1 to the apparatus illustrated in Fig. 2 which includes a body 17, only a part of which is shown in the drawing, and which is stationary when the apparatus is in use. A slide 18 is mounted on the body and guided thereby for movement relative to the body in directions along an axis 19 of the apparatus, which axis is normally upright in use. The body includes a support 20 for the fiflin 1 0, the support being annular and having a recess which can receive an end portion of the wall 13 to limit movement of the fitting along the axis 19 and transversely of the axis. It will be noted that there is freedom for considerable movement of the fitting transversely of the axis whilst remaing in the recess but that the fitting will normally be maintained by gravity in the lowest position permitted by the support 20. When seated in the recess, the fitting is constrained by the support having its axis at least approxi mately coinciding with the axis 19.

There is mounted on the slide 18 for rotation relative thereto about the axis 19 a work roller 21 provided with drive means 22 for rotating the roller about its axis. The drive means may comprise an electric motor and a belt and pulley transmission. The roller 21 includes annular lands 23 and 24 which are spaced apart axially by a distance correspond ing to the axial spacing between the grooves 14 and 15. By reciprocation of the slide 18, the roller 21 can be moved between a retracted position illustrated in the drawing, in which the roller lies almost entirely below the surface of the support 20 on which the fitting 10 rests and an operative position in which the lands 23 and 24 lie directly opposite to the grooves 14 and 15.

The apparatus further comprises a pressure roller 25 which is mounted on a carrier 26 for free rotation relative thereto about a pressure roller axis 27 which is parallel to the axis 19 of the work roller. The carrier 26 is guided on the body 17 for reciprocation in a direction perpendicular to the work roller axis 19 and a piston and cylinder unit 28 is provided for reciprocating the carrier between the retracted position shown in the drawing, in which the pressure roller 25 is clear of the fitting 10, and an operative position in which the pressure roller engages the fitting. The pressure roller has a larger diameter than does the work roller.

In use of the apparatus, the fitting 10 is placed on the support 20 whilst the work roller 21 and the pressure roller 25 are in their respective retracted positions. The work roller 21 is then moved along the axis 19 to its operative position in which a part of the roller is disposed within the fitting 10. It will be noted that the diameter of the lands 23 and 24 is somewhat less than the internal diameter of the rings 11 and 12 so that axial movement of the work roller can occur without axial movement of the fitting. The pressure roller 25 is then advanced towards the axis 19 into engagement with the external surface of the wall 13.By continued movement of the pressure roller, there is exerted on the wall 13 by the pressure roller a force directed towards the axis 19 which causes displacement of the fitting in a direction transverse to the axis 19 so that the solder rings 11 and 12 engage the lands 23 and 24 of the work roller. Each solder ring is trapped and squeezed between the work roller and the wall 13. The work roller is rotated by the drive means 22 and imparts rotation to the solder rings and to the wall 13 so that all parts of each ring are successively squeezed by the corresponding land. Since the wall 13 is in pressure rolling contact with the roller 25, this roller also rotates.

The solder rings 11 and 12 are pressed into their respective grooves 14 and 15 by the combined action of the rollers 21 and 25. The squeezing action of these rollers decreases the transverse cross-sectional area of each solder ring and increases the circumferential length of the piece of solder so that the diameter of the ring is increased and the gap 16 between the ends of the ring is closed until each ring lies entirely within the corresponding groove in the wall 13. Preferably, the axial dimension of each of the lands 23 and 24 is somewhat less than the axial dimension of each of the grooves 14 and 15 so that the lands can penetrate slightly into the grooves and displace each solder ring radially outwardly from the internal surface of the wall 13. The rolling may effectively work the ring of solder into an endless ring.

Whilst it is possible for the work roller 21 to be rotated only when it is in rolling contact with the solder rings, the work roller is preferably rotated continuously. It will be appreciated that instead of moving the work roller along the axis 19 into the pipe fitting, the pipe fitting may be moved along the axis to avoid axial displacement of the roller. Furthermore, the roller may be provided with a number of lands exceeding two for acting on the solder rings of a plurality of coaxial pipe fittings concurrently. On the other hand, when the roller is used to act on the solder rings of a pipe fitting which is an elbow, only a single land of the roller would be used.

Claims

1. A process in which a ring of solder is supported on a radially expandible mandrel at a position inside a pipe fitting, the mandrel is expanded to expand radially the ring sufficiently for axial movement of the ring relative to the fitting to be restrained, the mandrel then contracts and relative axial movement of the mandrel and fitting is effected to withdraw the mandrel from the fitting.

2. A process according to Claim 1 wherein prior to expansion of the mandrel the ring is placed on the outside of the mandrel, the pipe fitting is aligned axially with the mandrel and relative axial movement of the pipe fitting and mandrel occurs until the ring is disposed within the pipe fitting and at the required position along the fitting.

3. A process according to Claim 1 or Claim 2 wherein there is no axial movement of the mandrel relative to the ring whilst the mandrel is being expanded.

4. A process according to Claim 3 wherein the mandrel is resiliently stressed when it is expanded and is subsequently permitted to contract.

5. A process according to any preceding claim wherein the ring is squeezed against the internal surface of a wall of the fitting.

6. A process according to Claim 5 wherein, after the mandrel has been withdrawn from the fitting, rolling pressure contact is established between the ring and a work roller so that the ring is squeezed between the work roller and the internal surface of a wall of the fitting.

7. A process according to Claim 6 wherein pressure contact is maintained between the solder ring and the work roller by a pressure member which is maintained in rolling contact with an external surface of said wall of the fitting whilst rolling pressure contact is maintained between the ring and the work roller.

8. A process according to Claim 7 wherein the pressure member is a pressure roller which rotates about an axis parallel to an axis of rotation of the work roller.

9. A process according to Claim 8 wherein the work roller is driven.

10. Apparatus for use in a process according to Claim 1 comprising a radially expandible mandrel and means for expanding same, the mandrel having a first abutment for limiting movement along the mandrel of the solder ring when placed on the mandrel and a second abutment for limiting movement along the mandrel of the pipe fitting when placed on the mandrel.

11. Apparatus according to Claim 10 wherein the mandrel is hollow and has a wall in which there is formed a plurality of slits which are spaced apart circumferentially of the mandrel, each slit extending axially from an end of the mandrel past the first abutment.

12. A process for loosely engaging a solder ring in a pipe fitting substantially as herein described with reference to Fig. 1 of the accompanying drawings.

13. A process for providing a solder ring in a pipe fitting substantially as herein described with reference to Figs. 1 and 2 of the accompanying drawings.

14. Apparatus substantially as herein described with reference to and as illustrated in Fig. 1 of the accompanying drawings or substantially as herein described with reference to and as illustrated in Figs. 1 and 2 of the accompanying drawings.

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