GB2155576A

GB2155576A - Pipe couplings

Info

Publication number: GB2155576A
Application number: GB08506012A
Authority: GB
Inventors: Graham Felton
Original assignee: Hepworth Plastics Ltd
Current assignee: Hepworth Plastics Ltd
Priority date: 1984-03-09
Filing date: 1985-03-08
Publication date: 1985-09-25
Also published as: GB8406226D0; GB8506012D0; GB2155576B

Abstract

A toggle ring (7) for a push-in pipe coupling has a frusto-conical portion (8) with teeth (17) integral with one end of a cylindrical portion (14) the other end of which is integral with an inwardly directed annular flange (15), which substantially increases the radial stiffness of the toggle ring so it retains its shape when gripping a pipe (4) inserted in the socket (1). An annular element (10) with a flange (11) forms part of a thin stainless steel end cap (19) having a skirt (22) terminating in an inturned bead (23) engaging a groove (24) in the outside of the socket (1), thus ensuring an overall outside diameter of the coupling appreciably less than with a plastics end cap. The bead (23) also affords added hoop strength to resist radial expansion under pressurisation of the coupling. <IMAGE>

Description

SPECIFICATION Pipe couplings This invention relates to pipe couplings of the type comprising at least one pipe socket (usually of plastics material) having a first socket portion for receiving an end portion of a pipe as a close sliding fit and a second socket portion with a larger internal diameter towards the mouth of the socket, defining between the socket portions a first annular shoulder, a toggle ring (usually of thin stainless steel) housed in the second socket portion adjacent the first annular shoulder and having a frustoconical portion extending axially and radially inwardly of the socket to a terminal edge at a lesser diameter than the inside of the first socket portion, so as to be able to penetrate into and secure an inserted pipe against withdrawal from the coupling, an annular element in the mouth of the socket and having an inner diameter not less than the inside of the first socket portion, defining a second annular shoulder facing towards the first annular shoulder, and a resilient sealing ring housed between the toggle ring and the second annular shoulder. The frusto-conical portion of the toggle ring usually has slits or notches extending from its terminal edge to enable it to open to facilitate insertion of a pipe. A washer may be provided between the toggle ring and the sealing ring so that the sealing ring cannot be damaged by the toggle ring.

In known pipe couplings of this type (see GB-PS 1 520 150 and GB-PS 1 569 400) the toggle ring has a cylindrical portion integral with the outside of the frusto-conical portion. In order to achieve a pipe insertion force which is sufficiently low to enable manual insertion of a pipe into the socket, whilst at the same time minimising the overall diameter of the toggle ring, the radial slits or notches preferably extend to the outer edge of the frusto-conical section. With this known and hitherto preferable form it has been found that the toggle ring has a low radial stiffness and may be deformed from its initial circular shape by mechanical handling before or during assembly of the ring into the second socket portion or during insertion of the pipe into the pipe socket or by subsequent nonaxial mechanical loading of the pipe joint.

It is a disadvantage of the known pipe couplings that such deformation of the toggle ring may significantly reduce the security of retention of the pipe in the socket.

It is a further disadvantage of the known pipe couplings that the toggle ring may not be maintained in a perpendicular relationship with the axis of the pipe during pipe insertion or subsequent mechanical loading, which may also reduce the security of retention of the pipe in the socket.

It is a further disadvantage of both of the above known couplings that they comprise at least four component parts, in addition to the socket, which makes them expensive to manufacture and also makes automated assembly difficult and expensive, especially as most pipe couplings or pipe fittings have at least two sockets, differently directed, and each requiring the same component parts.

The primary object of the present invention is to provide a pipe coupling which overcomes the disadvantages of the known pipe couplings. A secondary object is to facilitate automated assembly of such pipe couplings.

According to the present invention, the toggle ring in a pipe coupling of the type initially defined has a cylindrical portion integral at one end with an inwardly directed annular flange next to the sealing ring and integral at the other end with the outside of the frustoconical portion which extends away from the flange.

The annular flange of the toggle ring substantially increases the radial stiffness of the toggle ring thus ensuring that the toggle ring retains its circular shape during mechanical handling and when performing its function of gripping and retaining a pipe inserted in the socket. The inner diameter of the flange is preferably substantially the same as the internal diameter of the first socket portion and a close sliding fit on the outer surface of the inserted pipe. The toggle ring is thereby maintained in a plane perpendicular to the axis of the pipe during pipe insertion and subsequent mechanical loading of the joint.

The flange of the toggle ring being next to the sealing ring, thus serves-in place of a washer-to prevent the sealing ring from making contact with and being damaged by the frusto-conical portion of the toggle ring and also, in conjunction with the second annular shoulder, to define a housing for the sealing ring. The inner edge of the flange is preferably turned axially towards the frusto-conical portion of the toggle ring, to provide a lead-in for an inserted pipe, the flange conveniently being formed with a semicircular or greater than semi-circular cross-section by rolling or spinning it inwards from that end of the cylindrical portion after the frusto-conical portion has been formed at the other end of the cylindrical portion.

The frusto-conical portion preferably has slits or notches dividing its terminal edge and forming a number of teeth, each of which is preferably bent slightly about a medial line to increase its resistance to buckling and to form points for engaging and biting into an inserted pipe. The first annular shoulder in the socket is preferably frusto-conical and preferably has a cone angle appreciably less than the cone angle of the frusto-conical portion of the toggle ring.

Although the annular element in the mouth of the socket may be a radially and preferably axially inwardly projecting portion of a plastics end cap secured to the outside of the socket by mating screwthreads on the socket and inside a skirt of the end cap (see GB-PS 1 520 150), or an annular plastics plug with an annular flange abutting the rim of the socket mouth and welded thereto (see GB-PS 1 569 400), according to a feature of independent significance the annular element preferably makes engagement with the socket to hold itself in place.Thus, the annular element may be formed of thin stainless steel with a cylindrical portion having an internal diameter substantially the same as the internal diameter of the first socket portion, and with integral inner and outer outwardly extending annular end flanges, the inner end flange having its terminal edge divided into barbs for biting into the inside of the second socket portion when the outer end flange abuts the rim of the socket mouth or lies within an annular rebate in the socket mouth.

Alternatively, and again of independent significance, the annular element may be part of a thin stainless steel end cap having an annular portion overlying and extending radially inwards from the rim of the socket mouth, a skirt integral with the outside of the annular portion and terminating in an inturned bead engaging in a peripheral groove in the outside of the second socket portion, and a cylindrical portion integral with the inside of the annular portion extending into the second socket portion with an inside diameter substantially the same as the internal diameter of the first socket portion and terminating in an outwardly extending annular flange providing the second annular shoulder; the inturned bead and the outwardly extending annular flange are conveniently both formed with a semicircular cross-section by rolling or spinning them respectively inwards and outwards from the skirt and cylindrical portion respectively. The skirt of the thin stainless steel end cap adds but little to the outside diameter of the socket, thereby ensuring an overall outside diameter of the coupling appreciably less than with a plastics end cap, and the bead of the skirt also affords added hoop strength to resist radial expansion under fluid pressurisation of the coupling.

An inwardly directed shoulder is preferably provided at the end of the first socket portion remote from the second socket portion to serve as a stop for an inserted pipe end, which shoulder may be the end of a bore of a pipe integral with the socket. Alternatively the socket may be one end of a coupling sleeve, bend or elbow, the other end of which has a similar socket with toggle ring, sealing ring and cap or it may be on one branch of a junction fitting (e.g. a tee) having a similar socket with toggle ring, sealing ring and cap on each of its other branches, or it may be integral with a connector for a tank or a tap.

The resilient sealing ring may be an O-ring.

Two embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a part-sectioned elevation of a pipe coupling in accordance with the invention; Figure 2 corresponds to the right-hand end of Fig. 1 but shows a pipe inserted into the socket; and Figure 3 corresponds to the upper part of Fig. 1 but shows another pipe coupling in accordance with the invention.

In Figs. 1 and 2 each pipe socket 1 of a plastics coupling sleeve has a first socket portion 2 for receiving an end portion 3 of a pipe 4 as a close sliding fit and a second socket portion 5 with a larger internal diameter towards the mouth of the socket, defining between the socket portions a first annular shoulder 6, a toggle ring 7 of thin stainless steel housed in the second socket portion 5 adjacent the first annular shoulder 6 and having a frusto-conical portion 8 extending axially and radially inwardly of the socket to a terminal edge 9 at a lesser diameter than the inside of the first socket portion, so as to be able to penetrate into and secure the inserted pipe 4 against withdrawal from the coupling, an annular element 10 in the mouth of the socket 1 and having an inner diameter not less than the inside of the first socket portion 2, defining a second annular shoulder 11 facing towards the first annular shoulder 6, and a resilient sealing ring 12 housed between the toggle ring 7 and the second annular shoulder, and wherein the toggle ring 7 has notches 13 extending from its terminal edge 9 to enable it to open to facilitate insertion of the pipe 4.

The toggle ring 7 also has a cylindrical portion 14 integral at one end with an inwardly directed annular flange 15 next to the sealing ring 12 and integral at the other end with the outside of the frusto-conical portion 8 which extends away from the flange.

The annular flange 15 substantially increases the radial stiffness of the toggle ring 7 thus ensuring that it retains its circular shape during mechanical handling and when performing its function of gripping and retaining the pipe 4 inserted in the socket. Being next to the sealing ring 12, the flange 15 serves to prevent the sealing ring from making contact with and being damaged by the frusto-conical portion 8 of the toggle ring 7 and also, in conjunction with the second annular shoulder 11, to define a housing for the sealing ring.

The inner diameter of the flange 15 is substantially the same as the internal diameter as the first socket portion 2 and a close sliding fit on the outer surface of the pipe 4, and the inner edge 16 of the flange 15 is turned axially towards the frusto-conical por tion 8 (by the flange being rolled or spun to a semi-circular cross-section), to provide a lead in for the inserted pipe end 3.

Teeth 17 formed by the notches 9 in the frusto-conical portion 8 of the toggle ring 7 are each bent slightly about a medial line to increase resistance to buckling and to form points 18 for engaging and biting into the inserted pipe 4. The first annular shoulder 6 in the socket 1 is frusto-conical and has a cone angle less than the cone angle of the frusto-conical portion 8 of the toggle ring 7.

In Figs. 1 and 2 the annular element 10 is part of a thin stainless steel end cap 19 having an annular portion 20 overlying and extending radially inwards from the rim 21 of the socket mouth, a skirt 22 integral with the outside of the annular portion 20 and terminating in an inturned bead 23 engaging in a peripheral groove 24 in the outside of the second socket portion 5, and a cylindrical portion 10 integral with the inside of the annular portion 20 extending into the second socket portion with an inside diameter substantially the same as the internal diameter of the first socket portion 2 and terminating in an outwardly extending annular flange providing the second annular shoulder 11.The inturned bead 23 and the outwardly extending annular flange 11 are both formed with a semicircular cross-section by rolling or spinning them respectively inwards and outwards from the skirt 22 and the cylindrical portion 10 respectively of the cap 19.

The skirt 22 of the cap 19 adds but little to the outside diameter of the socket 1 (especially compared with a plastics cap as previously referred to with reference to GB-PS 1 520 150) and the bead 23 also affords added hoop strength to resist radial expansion under fluid pressurisation of the coupling. The tapered portion 25 of the cap 19 and the rim 21 of the socket mouth within it may be formed with a greater degree of taper than that shown in Figs. 1 and 2, so as to afford the coupling an even more streamlined appearance.

An inwardly directed shoulder 26 (formed by one side of an internal central flange 27) is provided at the end of the first socket portion 2 remote from the second socket portion 5 to serve as a stop for the inserted pipe end 3, which-however-is preferably pulled back (as indicated by Fig. 2) manually to ensure the points 18 of the teeth 17 of the frusto-conical portion 8 of the toggle ring 7 have bitten into the inserted pipe before fluid pressurisation of the coupling.

Fig. 3 shows a simpler form of coupling sleeve than that of Figs. 1 and 2, but with like parts represented by like references, the differences being that the flange 15 of the toggle ring 7 is not of semicircular crosssection, and that the annular element 10 is formed of thin stainless steel with a cylindrical portion having an internal diameter substantially the same as the internal diameter of the first socket portion 2, with an integral inner flange 11 (likewise not of semicircular crosssection) having its terminal edge divided into barbs 28 for biting into the inside of the (longer) second socket portion 5 when an outer integral flange 29 lies within an annular rebate 30 in the socket mouth.

Claims

1. A pipe coupling comprising at least one pipe socket having a first socket portion for receiving an end portion of a pipe as a close sliding fit and a second socket portion with a larger internal diameter towards the mouth of the socket, defining between the socket portions a first annular shoulder, a toggle ring housed in the second socket portion adjacent the first annular shoulder and having a frustoconical portion extending axially and radially inwardly of the socket to a terminal edge at a lesser diameter than the inside of the first socket portion, so as to be able to penetrate into and secure an inserted pipe against withdrawal from the coupling, an annular element in the mouth of the socket and having an inner diameter not less than the inside of the first socket portion, defining a second annular shoulder facing towards the first annular shoulder, and a resilient sealing ring housed between the toggle ring and the second annular shoulder and wherein the toggle ring has a cylindrical portion integral at one end with an inwardly directed annular flange next to the sealing ring and integral at the other end with the outside of the frusto-conical portion which extends away from the flange.

2. A pipe coupling as in Claim 1, wherein the inner diameter of the flange is substantially the same as the internal diameter of the first socket portion and a close sliding fit on the outer surface of the inserted pipe.

3. A pipe coupling as in Claim 1 or Claim 2, wherein the inner edge of the flange is turned axially towards the frusto-conical portion of the toggle ring, to provide a lead-in for an inserted pipe.

4. A pipe coupling as in Claim 3, wherein the flange is formed with a semicircular or greater than semi-circular cross-section by rolling or spinning it inwards from that end of the cylindrical portion after the frusto-conical portion has been formed at the other end of the cylindrical portion.

5. A pipe coupling as in any one of Claims 1 to 4, wherein the frusto-conical portion has slits or notches dividing its terminal edge and forming a number of teeth.

6. A pipe coupling as in Claim 5, wherein each tooth is bent slightly about a medial line to increase its resistance to buckling and to form points for engaging and biting into an inserted pipe.

7. A pipe coupling as in any one of Claims 1 to 6, wherein the first annular shoulder in the socket is frusto-conical.

8. A pipe coupling as in Claim 7, wherein the cone angle of the first annular shoulder is appreciably less than the cone angle of the frusto-conical portion of the toggle ring.

9. A pipe coupling as in any one of Claims 1 to 8, wherein the annular element in the mouth of the socket makes engagement within the socket to hold itself in place.

10. A pipe coupling as in Claim 9, wherein the annular element is formed of thin stainless steel with a cylindrical portion having an internal diameter substantially the same as the internal diameter of the first socket portion, and with integral inner and outer outwardly extending annular end flanges, the inner end flange having its terminal edge divided into barbs for biting into the inside of the second socket portion when the outer end flange abuts the rim of the socket mouth or lies within an annular rebate in the socket mouth.

11. A pipe coupling as in any one of Claims 1 to 8, wherein the annular element in the mouth of the sockets is part of a thin stainless steel end cap having an annular portion overlying and extending radially inwards from the rim of the socket mouth, a skirt integral with the outside of the annular portion and terminating in an inturned bead engaging in a peripheral groove in the outside of the second socket portion, and a cylindrical portion integral with the inside of the annular portion extending into the second socket portion with an inside diameter substantially the same as the internal diameter of the first socket portion and terminating in an outwardly extending annular flange providing the second annular shoulder.

12. A pipe coupling as in Claim 11, wherein the inturned bead and the outwardly extending annular flange are both formed with a semicircular cross-section by rolling or spinning them respectively inwards and outwards from the skirt and cylindrical portion respectively.

13. A pipe coupling as in any one of Claims 1 to 12, wherein an inwardly directed shoulder is provided at the end of the first socket portion remote from the second socket portion to serve as a stop for an inserted pipe end.

14. A pipe coupling as in Claim 13, wherein the shoulder at the end of the first socket portion remote from the second socket portion is the end of a bore of a pipe integral with the socket.

15. A pipe coupling as in Claim 13, wherein the socket is one end of a coupling sleeve, bend or elbow, the other end of which has a similar socket with toggle ring, sealing ring and cap or it is on one branch of a junction fitting having a similar socket with toggle ring, sealing ring and cap on each of its other branches.

16. A pipe coupling as in Claim 13, wherein the socket is integral with a connector for a tank or a tap.

17. A pipe coupling substantially as hereinbefore described with reference to Figs. 1 and 2 of the accompanying drawings.

18. A pipe coupling substantially as hereinbefore described with reference to Fig. 3 of the accompanying drawings.