AU2018101628A4 - Improved Joint Between Two Plastics Pipes and a Method for Making Such a Joint - Google Patents

Abstract

Abstract A joint between two plastics pipes and a method of forming such a joint, where the male part of the joint provides an external surface adjacent the end of the pipe being joined; this surface supports a seal encircling the surface and providing at least one 5 protruding annular ridge; also provided on the male portion of the joint is a rib which encircles the external surface of the pipe adjacent the seal supporting surface, with the face of the rib abutting the seal being formed as an interrupted edge; the female part of the joint provides a collar at the joining end of the pipe, this collar is proportioned to be a snap fit over the male portion of the joint and provides a first shoulder which 10 engages the rib when the collar is snap fitted over the male portion, and a second shoulder which engages the end of the pipe; the method of making the joint includes forming the male and female components and then forcing them together to form the joint with the male portion of the joint and seal at an ambient temperature and the female portion of the joint within its thermoplastic temperature range.

Description

Improved Joint Between Two Plastics Pipes and a Method for Making Such a

Joint

Technical Field

The present invention relates to an improvement in a joint between two plastics pipes, and to a method for making such a joint, where the joint permits relative rotation of the two pipes.

The joint of the present invention has been designed for joining the pipes forming two io plumbing fittings together, and will therefore be described with particular reference to this application. However, it will be appreciated that the joint and method of the present invention could be applied to plastics pipes used for other purposes.

Background Art is The pipes forming parts of plumbing fittings often are installed in confined spaces, and often have to turn through multiple angles to provide a path between the plumbing installation, (e.g. a sink) and the wastewater outlet, and to provide (in many cases) a water trap between the inlet on the outlet, as required by sanitary regulations.

It follows that the pipes forming the plumbing fittings often have to be capable of providing a path with a number of bends and turns. The regulations do not permit the use of flexible pipes, and obviously it would be extremely expensive to custom make each set of pipes for a particular application. There is therefore a demand for pipes which can be joined together by reliably watertight joints. To allow the adjacent sections of pipe to be bent at angles to each other, these joints need to be rotatable without any loss of water tightness, so that adjacent sections of pipe can be moved easily and rapidly into the required configuration to fit in any particular space.

Since plastic pipes were first introduced for plumbing purposes, there have been a large number of different proposals for joints of the above described type. Many of the known joints do not completely fulfil the above objectives; some fulfil the above objectives but are expensive to manufacture and/or awkward to fit in situ.

2018101628 30 Oct 2018

Disclosure of Invention

An object of the present invention is to provide a joint between adjacent plastics pipes which fulfils the above requirements and is also inexpensive to manufacture and reliable in use.

The present invention provides a joint between two plastics pipes, one pipe providing the male portion of the joint adjacent one end of said pipe, and the other pipe providing the female portion of the joint adjacent one end of said other pipe, wherein:

• the male portion of the joint provides an external surface adjacent said one end io of said pipe, said surface supporting a seal which encircles said surface and provides at least one protruding annular ridge;

• the male portion of the joint further providing a rib encircling the external surface of said pipe adjacent said seal supporting surface, around the edge of the seal supporting surface furthest from said one end of said pipe;

is · the face of said rib abutting said seal being formed as an interrupted edge;

• the female portion of the joint providing a collar at said one end of said other pipe, said collar being proportioned and dimensioned to be a snap fit over the male portion of the joint;

• said collar providing a first shoulder dimensioned and located so as to engage 20 said rib when said collar is snap fitted over the male portion of the joint;

• said collar further providing a second shoulder dimensioned and located so as to engage said one end of said pipe when said collar is snap fitted over the male portion of the joint;

• said male and female portions of the joint being constructed and dimensioned 25 such that when said male portion is fully engaged with said female portion to form said joint, there is a smooth transition across said joint on the interior of the joined pipes.

Preferably, the edge of said seal adjacent said one end of said pipe leaves a portion of said seal supporting surface exposed around said end, and said collar further provides 30 a third shoulder dimensioned and arranged to engage said exposed surface and the edge of said seal adjacent said one end of said pipe, when said collar is snap fitted over the male portion of the joint.

Preferably also, the interior surface of said collar is formed with an annular groove to 35 correspond to the or each annular ridge on the seal.

2018101628 30 Oct 2018

Preferably also, said rib is provided by an annular surface encircling said pipe, said annular surface being tapered such that the thickness of said surfacing increases in a direction away from said end of said pipe.

The present invention further provides a method of making a joint between two plastics pipes, wherein one pipe provides the male portion of the joint adjacent one end of said pipe, and the other pipe provides the female portion of the joint adjacent one end of said other pipe, said method including:

• forming the male portion of the joint to provide an external surface adjacent io said one end of said pipe, said surface being adapted to support a seal which encircles said surface and provides at least one annular ridge;

• forming the male portion of the joint to provide a rib encircling the external surface of said pipe adjacent said seal supporting surface around the edge of the seal supporting surface furthest from said one end of said pipe, the face of said rib abutting is said seal being formed as an interrupted edge;

• fitting said seal on to said seal supporting surface;

• forming the female portion of the joint with a collar at said one end of said other pipe, said collar being proportioned and dimensioned to be a snap fit over the male portion of the joint;

· said collar providing a first shoulder dimensioned and located so as to engage said rib when said collar is snap fitted over the male portion of the joint;

• said collar further providing a second shoulder dimensioned and located so as to engage said one end of said pipe when said collar is snap fitted over the male portion of the joint;

· wherein the joint between the two plastics pipes is formed when the male portion of the joint and the seal are at or near ambient temperature and the female portion of the joint is within its thermoplastic temperature range, such that when said collar is snap fitted over the male portion of the joint, the collar shrinks as it cools and the or each ridge on the seal forms a corresponding groove in the adjacent interior surface of the collar;

• said male and female portions of the joint being constructed and dimensioned such that when said male portion is fully engaged with said female portion to form said joint, there is a smooth transition across said joint on the interior of the joined pipes.

Preferably, the seal is moulded onto said seal supporting surface.

2018101628 30 Oct 2018

Preferably also, the edge of said seal adjacent said one end of said pipe leaves a portion of said seal supporting surface exposed around said end, and said collar further provides a third shoulder dimensioned and arranged to engage said exposed surface and the edge of said seal adjacent said one end of said pipe, when said collar 5 is snap fitted over the male portion of the joint.

Preferably also, said rib is provided by an annular surface encircling said pipe, said annulur surface being tapered such that the thickness of said surface increases in a direction away from said pipe.

Brief Description of Drawings

By way of example only, a preferred embodiment of the present invention is described in detail with reference to the accompanying drawings, in which:Figure 1 shows a cross-section through the male and female parts of a joint in is accordance with the present invention;

Figure 2 shows a cross-section of the male and female parts engaged to form a rotatable joint;

Figure 3 shows a cross-section of part of the joint on an enlarged scale;

Figure 4 is an end view of the male part of the joint;

Figure 5 is a side view of the male part of the joint; and

Figure 6 is a cross-section through the male part of the joint

Best Mode for Carrying out the Invention

Referring to the drawings, a joint 10 between two sections of pipe 11, 12, includes a 25 male portion 13 carrying a seal 14, and a female portion 15. The pipes 11, 12 may be any of a wide range of types of plastics pipe, e.g. pipes forming parts of domestic or commercial plumbing fittings.

The joint 10 is required to join the pipes 11, 12 securely together, and provide a 30 watertight seal which allows rotation of one pipe relative to the other in a plane perpendicular to the longitudinal axes of the pipes across the joint 10; the axes are indicated in Figure 2 by broken line A - A.

The joint 10 described below in fact permits 360° rotation of one pipe relative to the 35 other. However, it is not essential that the joint should allow such a large angle of

2018101628 30 Oct 2018 rotation, and for some applications, stops may be moulded into the opposed surfaces of the pipes 11, 12 to limit the permitted degree of rotation.

The male portion 13 of the joint provides a flat annular surface 16 around the exterior 5 of the pipe 12 adjacent the end of the pipe on which the joint is formed. A tapered rib is formed around the exterior of the pipe 12 a short distance S from the end 18 of the pipe; the distance S is greater than the width W of the seal 14 (see Figure 1).

The rib 17 provides a first face 19 against which one edge of the seal 14 abuts (see io Fig. 3), and a second, wider, face 20. As shown in Fig. 4 and 5, the face 19 is formed as an interrupted edge, so as to provide a series of spaced faces 35 around the perimeter of the rib. The outer edge 36 of each face 35 (i.e. the edge in contact with the seal) is equidistantly spaced from the face 20, so that the abutting edge of the seal 14 is supported by the edges 36 at spaced intervals around the perimeter of the seal.

Figure 5 shows the faces 35 formed as castellations, i.e. rectangular formations equidistantly spaced around the rib 17.

However, the shape of the faces is not important:- what is important is that they combine to provide support for the perimeter of the seal, but require significantly less 20 material than the solid rib described and shown in parent specification number 631136.

Because of the reduction in volume of material used in the rib, the rib cools more rapidly than a solid rib:- this provides a cooler substrate over which to mould the seal 25 14. Moulding of the seal 14 onto a cooler substrate reduces any possible distortion of that end of the pipe during the moulding operation, and also means that the combined pipe plus seal itself cools more rapidly, so that it can be fitted onto the female part of the seal with less delay.

The rib 17 tapers such that the rib increases in width between the face 19 and the face 20. The taper of the rib 17 provides a lead-in angle when the pipes 11,12 are pushed together to form the joint, as described below, so that the end of the pipe 11 is expanded gradually as the interior of the collar 25 passes over the rib 17.

The seal 14 is moulded onto the end of the pipe and effectively is bonded to the underlying surface of the pipe such that it cannot be removed once installed. The seal

2018101628 30 Oct 2018 is annular and provides a base 21, one edge of which contacts the face 19 of the shoulder 17, and the other edge of which terminates a short distance D (S - W) away from the end of the pipe 12.

Integrally moulded with the base 21 of the seal 14 are two spaced parallel annular ridges 22, 23; the ridges may be the same height above the base 21 or may have different heights. The seal 14 may be formed with one, two, or more ridges.

The female portion 15 of the joint provides a collar 25 adjacent the end of the pipe 11 io at which the joint is formed; the collar 25 has a larger interior and exterior diameter than the remainder of the pipe, and may also have an increased wall thickness. The interior of the collar provides first, second and third spaced internally protruding annular shoulders 26, 27, 28.

is The first shoulder 26 is located adjacent the end of the pipe at which the joint is formed and is inclined at approximately 45° to the axis A-A of the joint. The second and third shoulders 28 and 27 are approximately 90° to the axis A-A, and are formed close to each other, with the distance D between the two shoulders equal to the width (S - W) of the exposed portion of the pipe 12 lying between the outer end of the seal 14 and 20 the end of the pipe 12. Between the shoulders 26 and 27 on the interior of the collar

25, the surface 31 of the female portion is substantially smooth, and is not formed with grooves to accommodate the ridges on the seal.

When the joint between the two pipes is formed, the male portion 13 and seal 14 are 25 cold, but the female portion 15 of the joint is snap fitted onto the male portion 13 of the joint when the female portion 15 is still hot from the moulding process (i.e. still within its thermoplastic range). Typically, for a polypropylene pipe, this temperate range is 210-230°C). When the female portion 15 is pressed into position, the first shoulder 26 rides over and engages the outer edge of the face 20 of the rib 17 on the male portion, 30 and the second shoulder 28 engages against the end of the pipe 12. The second shoulder 28 is dimensioned such that, when the joint is assembled, there is a smooth transition across the joint, on the interior of the pipes. The third shoulder 27 engages against the outer edge 30 of the seal 14. In this position, once the female portion of the joint has been snap fitted into place, it cannot move axially in either direction 35 because of the engagement of the shoulders as described above. However, the 45°

2018101628 30 Oct 2018 inclination of the shoulder 26 allows the male and female portions to be pulled apart if necessary

Although the inner surface 31 of the female portion is smooth between the shoulders

26 and 27, because the female portion is fitted when it is hot and thus shrinks onto the male portion as it cools, the ridges 22, 23 of the seal 14 form the inner surface 31 of the female portion between the shoulders 26 and 27 into two grooves corresponding exactly to the ridges 22 and 23. It will be appreciated that this provides a very tight seal, but also is an inexpensive method of manufacture, because it is unnecessary to io pre-form grooves in the inner surface 31 of the female portion. The resulting join permits relative rotation of the pipes 11,12 through 360°.

The joint normally would be made immediately after moulding the female portion 15 of the joint. However, it also would be possible to allow the portions 15 to cool after is moulding, and reheat them to a temperature within their thermoplastic range, before forming the joint.

It is possible to use a fitted seal 14 rather than a moulded on seal 14, but a moulded on seal is preferred because it is permanently fixed in position and thus permits a very 20 accurate alignment of the parts forming the joint.

Further, a moulded on the seal ensures a watertight joint between the seal 14 and the underlying male portion 13.

The pipes and the seal may be made of any suitable materials. For example, the pipes typically would be moulded from polypropylene and the seal from Santoprene (registered trade mark), a thermoplastic elastomer which is a mixture of polypropylene and rubber.

Claims (5)

Claims:

1. A joint between two plastics pipes, one pipe providing the male portion of the joint adjacent one end of said pipe, and the other pipe providing the female

5 portion of the joint adjacent one end of said other pipe, wherein:

• the male portion of the joint provides an external surface adjacent said one end of said pipe, said surface supporting a seal which encircles said surface and provides at least one protruding annular ridge;

• the male portion of the joint further providing a rib encircling the io external surface of said pipe adjacent said seal supporting surface, around the edge of the seal supporting surface furthest from said one end of said pipe;

• the face of said rib abutting said seal being formed as an interrupted edge;

• the female portion of the joint providing a collar at said one end of said is other pipe, said collar being proportioned and dimensioned to be a snap fit over the male portion of the joint;

• said collar providing a first shoulder dimensioned and located so as to engage said rib when said collar is snap fitted over the male portion of the joint;

20 · said collar further providing a second shoulder dimensioned and located so as to engage said one end of said pipe when said collar is snap fitted over the male portion of the joint;

• said male and female portions of the joint being constructed and dimensioned such that when said male portion is fully engaged with said

25 female portion to form said joint, there is a smooth transition across said joint on the interior of the joined pipes.

2. The joint as claimed in claim 1 wherein:

• the edge of said seal adjacent said one end of said pipe leaves a

30 portion of said seal supporting surface exposed around said end;

• said collar further provides a third shoulder dimensioned and arranged to engage said exposed surface and the edge of said seal adjacent said one end of said pipe, when said collar is snap fitted over the male portion of the joint;

35 · the interior surface of said collar is formed with an annular groove to correspond to the or each annular ridge on the seal; and

2018101628 30 Oct 2018 • said rib is provided by an annular surface encircling said pipe, said annular surface being tapered such that the thickness of said surface increases in a direction away from said end of said pipe.

5

3. The joint as claimed in claim 1 or claim 2 wherein the face of said rib abutting said seal formed as an interrupted edge provides a series of spaced faces around the perimeter of said rib, said faces in combination providing a support for the perimeter of the seal.

10

4. A method of making a joint between two plastics pipes, wherein one pipe provides the male portion of the joint adjacent one end of said pipe, and the other pipe provides the female portion of the joint adjacent one end of said other pipe, said method including:

• forming the male portion of the joint to provide an external surface is adjacent said one end of said pipe, said surface being adapted to support a seal which encircles said surface and provides at least one annular ridge;

• forming the male portion of the joint to provide a rib encircling the external surface of said pipe adjacent said seal supporting surface around the edge of the seal supporting surface furthest from said one end of said pipe, the

20 face of said rib abutting said seal being formed as an interrupted edge;

• fitting said seal on to said seal supporting surface;

• forming the female portion of the joint with a collar at said one end of said other pipe, said collar being proportioned and dimensioned to be a snap fit over the male portion of the joint;

25 · said collar providing a first shoulder dimensioned and located so as to engage said rib when said collar is snap fitted over the male portion of the joint;

• said collar further providing a second shoulder dimensioned and located so as to engage said one end of said pipe when said collar is snap fitted over the male portion of the joint;

30 · wherein the joint between the two plastics pipes is formed when the male portion of the joint and the seal are at or near ambient temperature and the female portion of the joint is within its thermoplastic temperature range, such that when said collar is snap fitted over the male portion of the joint, the collar shrinks as it cools and the or each ridge on the seal forms a

35 corresponding groove in the adjacent interior surface of the collar;

2018101628 30 Oct 2018 • said male and female portions of the joint being constructed and dimensioned such that when said male portion is fully engaged with said female portion to form said joint, there is a smooth transition across said joint on the interior of the joined pipes.

5. The method as claimed in claim 4 wherein the face of said rib abutting said seal formed as an interrupted edge provides a series of spaced faces around the perimeter of said rib, said faces in combination providing a support for the perimeter of the seal.