GB2120338A

GB2120338A - Pipe seal including adjustable expansion ring

Info

Publication number: GB2120338A
Application number: GB08212987A
Authority: GB
Inventors: Johannes Carolus Delhaes
Original assignee: BOLD VENTURE AG
Current assignee: BOLD VENTURE AG
Priority date: 1981-05-05
Filing date: 1982-05-05
Publication date: 1983-11-30
Also published as: IT8221082A0; FR2505435B3; DE3216682C2; NL187541C; IT1190805B; FR2505435A1; NL8102199A; NL187541B; DE3216682A1; GB2120338B

Abstract

A seal for use in a pipe joint between spigot and socket ends includes an expansion ring for clamping a gasket into sealing contact with the inner wall of the socket. The free ends of the expansion ring overlap and are provided with meshing teeth to prevent removal of the ring once it has been installed in expanded position. <IMAGE>

Description

SPECIFICATION Seal including adjustable expansion ring This invention relates to a seal for use in pipes to be fitted one into the other with spigot and socket ends, including a gasket made of an elastomeric material and arranged in said socket, which gasket is clamped against the inner wall of the socket by means of an expansion ring.

By pipes to be fitted one into another with spigot and socket ends are understood in this application all pipes which can be coupled to make pipe joints in which one pipe end (spigot end) can be inserted into a wider pipe portion (socket). This socket may be the widened end or a side-branch of another pipe, or an auxiliary member, such as a coupling sleeve or a tee piece, to which two or more pipes can be connected.

In a prior seal of this type, as described in German patent 629,981, the expansion ring is provided with screw-thread, and the desired clamping force is obtained by screwing alikewise threaded-conical bushing into the ring.

That construction is not suitable for use in cases in which there may be major dimensional variations of the inside diameter of the socket, such as in salt-glazed pipes. Another drawback is that the aid for tensioning the expansion ring forms part of the construction, and so, after tensioning the expansion ring, remains behind in the socket. This means not only an increase in cost of the seal, but has the additional disadvantage that during transport or storage of pipes provided with seals, the seals can be removed by unauthorized persons or become lost through other causes.

The present invention provides a seal in which the clamping ring for retaining the gasket in the socket can also be used with large dimensional variations of the socket, consists of a single part, and, after being mounted cannot be removed from the socket or with great difficulty only.

For that purpose the seal according to the present invention is characterized in that the free ends of the expansion ring overlap and are provided with meshing teeth.

The tensioning of the expansion ring is now effected by displacing the overlapping ends of the ring in the tangential direction relative to each other so that the diameter of the ring is increased.

When a torque spanner is used for this purpose, the gasket is always clamped in the socket with the same pre-determined force, irrespective of the dimension of the inside diameter of the socket.

After the torque spanner has been removed the ring remains locked in its operative position owing to the fact that the meshing teeth prevent the ring ends from sliding back.

Preferably one end of the expansion ring is provided with a tongue, which extends into a rabbet in the other end of the ring. This excludes the possibility of removing the ring by displacing the ring ends in the transverse direction relative to each other.

In one embodiment of the invention the expansion ring is provided with a radially outward flange Preferably the thickness of the lapping ends of the flange is so much less than the thickness at other places that the total thickness at the lap is equal to the thickness at these other places. At the rabbeted end, the flange extends tangentialiy beyond the rabbet.

Preferably, one end of the expansion ring is provided with teeth on the inside and the other on the outside. In case one end extends with a tongue into a rabbet of the other end, then the tongue is provided with teeth on the inside and the rabbet is provided with teeth on the side facing the gasket. As a result of the radially inward force exerted by the gasket on the expansion ring after the ring has been mounted under tension, the teeth are then forced together.

In a preferred embodiment of the invention, the rabbet is formed with a channel-shaped crosssectional configuration, with its open side directed outwardly, so that after the expansion ring has been tensioned, the resilient gasket is in contact with the tongue, and the latter bears on the teeth in the rabbet.

Naturally it is also possible to provide the teeth in radial planes, for example, by making the expansion ring in the form of a piston ring or key ring, in which case the ends of the ring lap as viewed in the axial direction.

According to the invention, the teeth may have the form of non-equilateral triangle in section, with the front face directed to the nearer end being steeper than the rear face. Displacing the ends of a ring mounted under tension, in such a manner that the diameter of the ring is decreased is then considerably more difficult than a displacement in the opposite direction.

Decreasing the diameter is rendered particularly difficult if the base angle of the teeth adjoining the steep front face is equal to, or larger than 900, as the teeth then interengage like barbs.

It is observed that it is known to secure flexible tubes to the end of a pipe by means of a so-called hose-clip, which consists of a toothed band to be applied around the tube for securing it and preventing unintentional loosening. Such a device, however, is unsuitable for exerting a force directed radially outwardly, and securing a gasket in the socket of a pipe.

One embodiment of the invention will now be described, by way of example with reference to the accompanying drawings.

In said drawings, Fig. 1 shows an elevational view in the axial direction of an expansion ring used in a seal according to the invention; Fig. 2 shows an elevational view taken on the line Il-Il of Fig. 1; Fig. 3 is a cross-sectional view taken on the line Ill-Ill of Fig. 1; Fig. 4 is a cross-sectional view taken on the line lV-lV of Fig. 1; Fig. 5 is a cross-sectional view taken on the line V-V of Fig. 1; Fig. 6 shows the teeth at the ends of the ring on a larger scale; Fig. 7 is a part-sectional perspective elevation, showing the ring with a gasket applied around it at the lap, with the ring being set back to its smallest diameter; Fig. 8 shows the lap after an increase in diameter of the expansion ring; and Fig. 9 shows an axial cross-sectional view of a pipe joint according to the present invention.

A sealing sleeve 1, made of an elastomeric material, such as rubber, consists of a cylindrical portion 2 and a hammer-head-shaped portion 3.

Provided on the inside of cylindrical portion 2 is a split ring 4, which is provided on its outer circumference with a circumferential groove 5, in which fits a circumferential ridge 6 present on the inside of cylindrical portion 2. Ring 4 has been made by injection moulding from a thermoplastic synthetic plastics material, such as polypropylene. It is also possible, however, to use metal rings.

Ring 4 is provided on one end with a tongue 7 and on the other end with a rabbet 8, and further with a flange 9 directed radially outwardly. Fig. 1 shows ring 4 in the non-mounted state, as it is removed from the mould after injection moulding.

For mounting ring 4 in sealing sleeve 1, ring 4 is pinched so that tongue 7 slides into rabbet 8.

Tongue 7 is provided on the inside with teeth 10, and rabbet 8 with teeth 11, which teeth intermesh after tongue 7 has been inserted into rabbet 8, so that expansion ring 4 is prevented from springing back into its original position. Sleeve 1 is now pushed over ring 4 to such an extend that circumferential ridge 6 falls into groove 5.

In the embodiment shown, flange 9 extends beyond the rabbet, and at the other end recedes somewhat relatively to tongue 7. Flange 9 and cylindrical portion 12 of ring 4 are thinner at ends 13 and 14 than at other places, so that they slide one over the other when the diameter of ring 4 is decreased, as shown in dash lines in Fig. 3.

Sleeve 1 is shifted with expansion ring 4 into socket 15 of a pipe 16 until flange 9 is in contact with the end face of the socket. Thereafter the ends of the ring are forced apart, for example, by means of a tool specifically made for the purpose, which engages the lugs 17 formed integrally with the ring. The diameter of expansion ring 4 is then increased, as a result of which the cylindrical wall 2 of sleeve 1 is omnilaterally clamped into contact with the inner surface of socket 1 5.

The distance through which ends 13, 14 of ring 4 are forced apart depends on the inner diameter of socket 1 5. With a maximum lap of the toothed parts 7, 8 of, for example, 65 mm, differences in diameter of 20 mm can be bridged.

The force with which the cylindrical wall 2 is forced by expansion ring 4 into contact with the inner wall of socket 15 can be set at a predetermined value by operating the expansion tool by means of a torque spanner set at the desired value. This has the advantage that under all conditions there is an effective seal along the inner wall of socket 15, which is of importance in particular in case the inner diameter of socket 15 is so wide that the hammer-head portion 3 of sleeve 1 does not ensure complete sealing.

As shown in Fig. 6, the teeth have the form, in section, of a non-equilateral triangle, with the steep side facing the nearer end. When the diameter of ring 4 is increased the teeth slide over each other along the less steep edges. Adjacent the teeth, ridge 6 on the inside of sleeve 1 is depressed an amount corresponding to the height of a tooth each time a tooth jumps. Teeth 10, 1 1 are then again forced to mesh by the radial resiliency of the sleeve. A sliding of teeth 10, 1 1 in such a direction that the diameter of the ring is decreased is impossible, owing to the fact that, as viewed in that direction, the teeth contact each other along the steep front edges.

This movement tending to reduce the diameter is particularly prevented owing to the fact that the base angle of the triangular teeth at the front edge is slightly greater than 900, so that the teeth are slightly undercut and hence interengage like barbs.

Rabbet 8 has a channel-shaped cross-sectional shape and links up with the circumferential groove 5. Teeth 1 1 are formed on the bottom of the rabbet. Tongue 7 is in contact with these teeth 11, and is axially confined between the upright walls of the channel-shaped rabbet 8. At the open side of the channel-shaped rabbet 8, facing the sealing sleeve 1, tongue 7 contacts the ridge 6 of the sleeve.

In joining pipes, a pipe 18 is inserted with its spigot end into socket 15. During this operation, pipe 18 first slides over expansion ring 4 and then over the hammer-head-shaped sealing portion 3 of sleeve 1. During this operation the lugs 1 7 on the inside of ring 4 serve to guide the spigot end of pipe 18.

Claims

1. A seal for use in pipes to be fitted one into the other with spigot and socket ends, including a gasket means of an elastomeric material and arranged in said socket, which gasket is clamped against the inner wall of the socket by means of an expansion ring, characterized in that the free ends of the expansion ring overlap and are provided with meshing teeth.

2. A seal as claimed in claim 1, wherein the one end of the expansion ring is provided with a tongue, which extends into a rabbet in the other end of the ring.

3. A seal as claimed in claim 1 or 2, wherein the expansion ring is provided with a radially outward flange having lapping ends whose thickness is so much less than the thickness at other places that the total thickness at the lap is equal to the thickness at said other places.

4. A seal as claimed in claim 3, wherein at the rabbeted end the flange extends tangentially beyond the rabbet.

5. A seal as claimed in claims 1-4, wherein one end of the expansion ring is provided with teeth on the inside, and the other end is provided with teeth on the outside.

6. A seal as claimed in claims 2-5, wherein the tongue is provided with teeth on the inside, and the rabbet is provided with teeth on the side facing the outer circumference of the expansion ring.

7. A seal as claimed in claims 1-6, wherein the rabbet has a channel-shaped cross-sectional configuration with its open side directed outwardly.

8. A seal as claimed in claims 1-7, wherein the teeth have the form of a non-equilateral triangle in section, with the front face directed to the.nearer end being steeper than the rear face.

9. A seal as claimed in claim 8, wherein the base angle adjoining the steep front face is equal to,orlargerthan,900.