GB2209373A

GB2209373A - Pipe coupling

Info

Publication number: GB2209373A
Application number: GB8820580A
Authority: GB
Inventors: Heinrich Eckermann
Original assignee: WAELZLAGER NORMTEILE VEB; VEB KOMBINAT WALZLAGER und NORMTEILE
Current assignee: WAELZLAGER NORMTEILE VEB; VEB KOMBINAT WALZLAGER und NORMTEILE
Priority date: 1987-09-02
Filing date: 1988-08-31
Publication date: 1989-05-10
Also published as: GB8820580D0; DE3827243A1; DD263575A1

Description

1 4 4 1 PIPE-JOINT 77 22093 j This invention relates to a screwed pipe

joint or coupling for radial and axial assembly, which can be used in any industrial application but especially in the hydraulics and pneumatics industry where pipes of coarse manufacturing tolerance and having surface irregularities are commonly used.

Screwed pipe joints for connecting pipes to each other or for connecting pipes with machine units are known in many forms which differ from each other greatly, depending on their compressive load capacity, dynamic load capacity, assemj)ly costs and service life. These screwed pipe joints have the disadvantage that they can only be used for connecting or joining seamless or welded precision steel tubing. Accordingly, high requirements are imposed in terms of diameter tolerances, dimensional and positional deviations in both the longitudinal and transverse directions. Furthermore, in accordance with the prevailing standards, only very slight surface irregularities are permitted on the outside and the inside of the pipe, 1 1. 1 1 2 - is since the sealing function of the packings of these screwed pipe joints is very much influenced by the quality of the outer surface or, respectively, the outer or inner surface of the pipes to which they are fitted. In addition, hardness defects lead directly to faulty assemblies and a reduced sealing effect.

A screwed joint is known, which consists of a socket, a sleeve nut and a conical welding nipple. The latter assumes the sealing function and acts as an adaptor to which the coarse-tolerance pipe is welded. These screwed joints are highly material-intensive and, by reason of the required welding operations, cannot be executed at any working site. In addition, strict dimensional requirements are imposed on the finish of the sealing surface of the conical nipple.

A pipe coupling is also known, in which a nut having a conical internal contour causes a metal ring fitting into the internal cone of the nut to taper radially when tightened and press it against the pipe, the said metal ring being frontally supported on studs so that it does not execute any axial movement. A chamber is formed in the zone of support of the ring on the studs 1, 1 j 1 1 is - 3 in which a zone subassembly forms the seal on the surface of the pipe. The disadvantage of this screwed joint is that it can only be used with precision steel pipe and not coarse-tolerance pipes, since the sealing takes place on the surface of the pipe and all the pipe parameters such as diameter tolerances, dimensional and positional deviations, surface quality have a direct effect on the quality of the seal. Moreover, the radial deformation of the conical ring requires large assembling forces.

Another screwed joint is known, in which a sleeve nut with an internal cone presses a metal ring having a corresponding external cone against a socket in such a manner, that it undergoes a radial deformation and bears against the pipe projecting into or passing through the ring and projecting into the socket whilst sealing said pipe on its outer surface, partly with the use of further sealing elements. This screwed joint has the drawback that it can only be used with precision steel tubing since the large dimensional tolerances and the permitted surface defects of coarse-tolerance pipes do not allow a reliable seal with their surfaces. Moreover, the requirements 1 - 4 imposed on dimensional precision and surface quality are very high.

is A still further screwed joint is known, which consists of a socket without an internal cone against which, by means of a sleeve nut, a compression ring in cooperation with a cutting ring is pressed. When the sleeve nut is tightened, the cutting ring cuts with sealing effect into the surface of the pipe. The compression ring is sealed relative to the socket by means of a plastic gasket. The disadvantage of this joint is again that precision steel tubing is required, because the cutting ring cannot be cut into coarse-tolerance tubing with the required cutting quality and'the joint is highly material-intensive owing to the compression ring-cutting ring combination. Also, two gasket elements are required, as well as a lengthened sleeve nut. Variations in pipe quality directly affect the quality of the sealing and the dynamic load bearing capacity and the assembling forces required are very high since the cutting ring must be radially deformed and pressed into the pipe.

1 - 5 It is an object of the invention to provide a screwed pipe joint which makes it possible to join to each other or to connect to machine units not only precision steel pipes but also coarse-tolerance pipes.

According to the invention, there is provided a pipe coupling comprising a socket to receive one end of a pipe, a coupling member which threadingly engages with said socket to connect the pipe thereto, the coupling member having a tapered surface which engages with a matching tapered surface provided on an axially slotted portion of a locking ring fitted around the end of the pipe inserted in the coupling member, a gasket located between an end face on the socket and the juxtaposed end of the pipe, the arrangement being such that on rotation of the coupling member, it moves axially towards the socket member whereby the slotted portion of the locking ring is radially compressed to engage the pipe and move it axially against the gasket whereby the end of the pipe compresses the gasket against the end face on the socket to form a seal therewith.

i 1 1 t 1 -1 - 6 An advantage of the coupling of the invention relative to the known solutions is that, especially where it is used for radial assembly, there is a considerable saving on material expenditure with a corresponding reduction in weight and assembly expenditure and, in contrast to the comparable screwed joints, is also interchangeable.

With the pipe coupling of the present invention, the gasket element or locking ring is so designed geometrically as to fit in combination with the resilient gasket that the functional reliability, including a high sealing effect, is ensured independently of the-variable tube properties (diameter-tolerance, unroundness, surface quality, strength, hardness, weld seam quality) to the full extent.

Preferably, the diameter of the slotted part of the locking ring is smaller than the diameter of the unslotted part. Desirably, the gasket has a cylindrical or bevelled contact surface, into which a cylindrical pipe centering surface or rebate is k 7 machined. The unslotted part of the IOCKIng ring may be provided with a smooth or bevelled contact surface.

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:Figure 1 shows a side elevation, partly in section, of a screwed pipe joint with a gasket element for radial assembly, Figure 2 shows a plan view of the gasket element of Figure 1, is Figure 3 shows a section of the gasket element of Figure 2 taken along the line A-A, Figure 4 shows a section of another gasket element with a stepped portion, Figure 5 shows a section of a packing element with a bevelled pipe centering portion, R - p Figure 6 shows a section of a gasket with a cone in its unslotted part, Figure 7 shows a side elevation, partly in section, of a screwed pipe joint and gasket element for axial assembly using a tightening screw incorporating a conical surface, Figure 8 is a side elevation, partly in section, of screwed pipe joint with a gasket element for axial assembly using a tightening screw without a conical surface, is Figure 9 is a side elevation, partly in section, of screwed pipe joint with a gasket element for axial assembly using a known socket having a 24 conical surface, and Figure 10 is a view similar to Figure 1.

Figure 1 shows a known angled connection socket 1 for radial assembly, connected to a pipe 5 with sealing effect by means of a subassembly consisting of. a sleeve nut 2, with a conical inner face 10, a gasket 3 and a - 9 locking ring 4. The locking ring 4 is provided in axial direction with four slots 6 connected by four webs 7 and, on the slotted side, with a 247 bevel at end 8. On the inner peripheral face of the locking ring 4, teeth 9 may be machined (see Figures 2 and 3).

metallic is During tightening of the sleeve nut 2 onto the connection socket 1, the locking ring 4 is axially pressed against the gasket 3, which is supported on a sealing surface 12 provided on the connection socket 1 and the front face of the pipe 5 bears against the gasket 3. On further tightening of the sleeve nut 2, the webs 7 of the slotted locking ring 4 are radially deformed in the bevelled region 8 and their toothed portion 9 is urged into the surface of the pipe 5. Still further tightening causes the front face of the pipe 5 to be pressed against the gasket 3. Owing to the action of the conical inner face 10 of the sleeve nut 2 during assembly there is transmitted not only a radially acting contact pressure through the webs 7 to the surface of the pipe 5, but an axially acting force component is also active which presses the pipe 5 1 10 axially against the gasket 3. By this means a very strong sealing effect is achieved.

Since the webs 7 of the locking ring 4 are much easier to deform radially than the known solid embodiments, the assembling force required is much smaller. A further advantage is that the sealing on the surface of the pipe 5 is not effected in the conventional manner, but instead only the locking ring 4 is tensioned by way of packing. Owing to this, the requirements imposed on the manufacturing qualities of the components (tolerances, surface properties) can be substantially reduced. Additionally, the performance of the sealing means are substantially independent of the pipe properties (dimensions, tolerances, dimensional and positional deviations, strength parameters and surface quality), so the joint can readily be used with coarsely toleranced pipes.

In another embodiment shown in Figure 7, the assembly of pipes 5 as in Figure 1 can be effected by using instead of the sleeve nut 2 a tightening screw with an inner cone 13 in conjunction with a connection. socket 14, gaskets 3 with pipe centering 11 and a slotted locking ring 15 which has a stepped-down shaft portion (see Figure 4). The screwed pipe joint shown in Figure 7 can be used for axial assembly and is suitable for sealingly connecting two pipes 5 located opposite each other. An important advantage of this embodiment is that the dimensions of the components can be reduced.

is Figure 8 shows another embodiment for the sealing connection of pipes 5 using a connection socket 16 having a conical inner surface 17 which cooperates sealingly with a subassembly consisting of gaskets 18, slotted locking rings 4 and tightening screws 19 having a plane inner contour. In consequence of the design of the components employed, this screwed connection is suitable for higher compressive and dynamic loading.

Figure 9 shows yet another pipe connection for axial assembly which consists or a connection socket 20. with conical inner surface 21, by means of which sleeve nuts 22, slotted locking rings 4, gaskets 18 and pipes 5 are joined with sealing effect.. In this arrangement, a pipe seat 23 is provided in the socket 20 to correspond with sockets 16 in the Figure 8 arrangement, -1 12 adapted to the tolerance conditions- when coarse-tolerance pipes are employed.

is 7 In the embodiments of Figures 8 and 9, the slotted locking ring 4 is supported with its unslotted face on the front face of the tightening screw 19 or the sleeve nut 22 respectively.

Figures 5 and 6 show alternative forms of gasket 3 and slotted locking rings 4 or 15. The gasket 3 of Figure 5 is provided with a contact surface 24 which is preferably bevelled at 600 and the locking ring 4a of Figure 6 has an inner bevel 25 on its unslotted part and t_he webs 7 are bevelled on their front face.

4 o 13

Claims

CLAIMS is 1. A pipe coupling comprising a socket to receive one end of a pipe, a coupling member which threadingly engages with said socket to connect the pipe thereto, the coupling member having a tapered surface which engages with a matching tapered surface provided on an axially slotted portion of a locking ring fitted around the end of the pipe-inserted in the coupling member, a gasket located between an end face on the socket and the juxtaposed end of the pipe, the arrangement being such that on rotation of the coupling member, it moves axially towards the socket member whereby the slotted portion of the locking ring is radially compressed to engage the pipe and move it axially against the gasket whereby the end of the pipe compresses the gasket against the end face on the socket to form a seal therewith.

1 14

2. A pipe coupling as claimed in claim 1 wherein the coupling member is internally threaded to engage with corresponding threads on the exterior of the socket.

is

3. A pipe coupling as claimed in claim 1 wherein the coupling member is externally threaded to engage with corresponding threads on the interior of the socket.

4. A pipe coupling as claimed in any of claims 1-3 wherein the locking ring directly engages with the gasket.

5. A pipe coupling as claimed in any of claims 1-3 wherein there is no contact between the locking ring and the gasket.

6. A pipe coupling as claimed in any one of the preceding claims wherein the slotted portion of the locking ring is provided at one end thereof.

k 1 A 1 C.1, W 1 i 5

7. A pipe coupling as claimed in claim 6, wherein the outside diameter of the slotted portion of the locking ring excluding the tapered surface thereon is the same as that of the remainder of said ring.

is

8. A pipe coupling as claimed in claim 6 wherein the outside diameter of the slotted portion of the locking ring is less than that of the remainder of said ring.

9. A pipe coupling as claimed in any of the preceding claims wherein the end of the ring remote from its slotted portion has a plane surface.

10. A pipe coupling as claimed in any one of claims 1-8 wherein the end of the ring remote from its slotted portin is bevelled or tapered.

11. A pipe coupling as claimed in any of the preceding claims wherein the interior of the locking ring which engages with the pipe is provided with teeth.

C1 C 16 -

12. A pipe coupling as claimed in any of the preceding claims wherein the gasket is annular and includes a cylindrical pipe end receiving rebate.

13. A pipe coupling as claimed in claim 12 wherein the exterior surface of the gasket is cylindrical.

14. A pipe coupling as claimed in claim 12 wherein the exterior surface of the gasket is bevelled or tapered.

is Q,

15. A pipe coupling comprising a connection socket with or without a sealing cone. with external thread or a connection socket with sealing cone and internal thread for the tensioning of gasket elements combining a metallic gasket with a resilient packing, with the pipe by means of a sleeve nut or tightening screw, respectively, with or without sealing cone, in which the metallic gasket may optionally have a profiled portion on its inner peripheral face, characterised in that the metallic gasket is constructed as a locking t 1 1 I ' ring which has a part provided with a plurality of slots on the front faces of which a bevel is located with cooperates with the internal cone in the sleeve nut, in the tightening screw, or in the connection sockets.

16. A pipe coupling substantially as herein described with reference to the accompanying drawings.

0, 1 Fl,bllshe: 1986 at The Patent Office. State House. 6671 Hi_.'. 11,.'bcrn London WC1R 4TP- Further copies may be obtained from The Patent Office, SEaes Branch, St Mary Cray, Orpington. Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray. Kent. Con. 1187.