WO1997034099A2

WO1997034099A2 - A pipe coupling

Info

Publication number: WO1997034099A2
Application number: PCT/NZ1997/000028
Authority: WO
Inventors: Albert Frederick Hansen
Original assignee: Hansen Developments Limited
Priority date: 1996-03-12
Filing date: 1997-03-12
Publication date: 1997-09-18
Also published as: AU2181697A; WO1997034099A3; AU711022B2

Abstract

A pipe coupling comprises a body part (1) having a hollow interior (4), a clamp nut (30) also having a hollow interior (32) and a die ring (20). The clamp nut (30) is threaded coaxially onto the body part (1) of the coupling and has a tapered interior. The die ring (20) is positioned within the tapered portion of the clamp nut (30) and has a gripping interior surface (23) and is connected to the clamp nut (30) so that the die ring (20) will rotate with the clamp nut (30). A pipe end (40) is inserted through the clamp nut (30) and the die ring (20) within the clamp nut (30), and into the body part (1) of the coupling. Rotation of the clamp nut (30) advances the clamp nut (30) onto the body part (1) and rotates the die ring (20) to force the threaded interior (23) of the die ring (20) into contact with the exterior wall of the pipe (40) to secure the pipe end in the coupling.

Description

A PIPE COUPLING

FIELD OF INVENTION

This invention relates to a pipe coupling and m particular a pipe coupling which is capable of enabling a pipe to be readily connected and disconnected to the pipe coupling and which is primarily but not necessarily for application to pipe formed of a rigid or semi rigid plastics material.

BACKGROUND

One form of pipe coupling disclosed in our New Zealand patent specification 264022 has a body part with a hollow interior and a rotatable sleeve mounted on the body part and having a tapered interior of narrowing diameter towards the pipe entry end of the sleeve. The pipe coupling includes a circular band which is coaxially positioned within the rotatable sleeve so that after the pipe end has been engaged within the body part of the pipe coupling the sleeve is rotated to force the circular band to close about the pipe end.

SUMMARY OF INVENTION

The present invention provides an improved or at least alternative form of pipe coupling.

In broad terms the invention comprises a pipe coupling comprising a body part having a hollow interior and a clamp nut having a screw threaded interior part by which the clamp nut is threaded coaxially onto the body part and a tapered interior part with a diameter which tapers with reducing diameter towards an end of the clamp nut opposite the threaded interior part, and a die ring positioned within the tapered portion of the clamp nut and having a gripping interior surface and means connecting the die ring to the clamp nut so that the die ring will rotate with the clamp nut, such that on insertion of a pipe end through the clamp nut and the die ring within the clamp nut and into the body part of the coupling, rotation of the clamp nut to advance the clamp nut onto the body part will rotate the die ring to force the gripping interior of the die ring into contact with the exterior wall of the pipe to secure the pipe end in the coupling.

Preferably the interior of the die ring is threaded or provided with one or more ribs to form the gripping interior surface of the die ring which will engage into the exterior wall of the pipe end as the clamp nut is rotated to advance the clamp nut. The interior gripping surface of the die ring may comprise a thread of a hand opposite to the hand of the threaded interior part of the clamp nut, so that rotation of the clamp nut to advance the clamp nut onto the body part will rotate the die ring to force the threaded interior of the die ring into contact with the exterior wall of the pipe to form a reverse thread, groove or circumferential of helical groove on the pipe end and move the die ring towards the entry end of the clamp nut (and further move the pipe end into the pipe coupling). Where the interior gripping surface of the die nng is provided with a reverse thread, preferably this is a thread of a finer pitch than the coarser pitch of the thread between the clamp nut and the body part of the coupling so that the die ring will move rearwardly on the pipe at a slower rate than the clamp nut moves forwardly onto the body part of the coupling on rotation of the clamp nut. Alternatively but less preferably, the interior gripping surface of the die ring may have a thread of the same hand as that between the clamp nut and the body part of the coupling, of a similar, finer, or coarser thread. Preferably the pipe coupling includes means to prevent the pipe end from rotating within the pipe coupling.

Preferably the die ring is split longitudinally to allow contraction and expansion of the die ring.

Preferably the die ring is formed of a resilient plastics material with a memory for the circular shape of the die ring.

Preferably the die ring includes a means to remove and contain pipe material cut from the exterior pipe wall by the action of the rotating die ring in such a manner that said removed material does not interfere with the action of the die ring.

Preferably the die ring includes a means of positively cutting a thread form, groove or other shape into the exterior wall of the pipe.

Preferably the pipe coupling includes an end seal within the bore of the body part which co-acts with a pusher ring capable of being compressed against the end seal when the clamp nut and die ring have been screwed onto the body part.

Preferably means are provided to retain the die ring in the clamp nut while the clamp nut is being unscrewed.

Preferably means are provided to ensure that the end seal is capable of sealing against both the exterior wall of the pipe and the bore of the body part. Preferably means are provided to ensure that the end seal is capable of maintaining both a pressure and/or a vacuum seal within predetermined limits, -dependent upon the condition of the fluid within the pipe.

BRIEF DESCRIPTION OF DRAWINGS

Preferred forms of couplings of the invention will now be described by way of example with the aid of the accompanying drawings, wherein:

Figure 1 is an exploded view of the disassembled components of a preferred form pipe coupling;

Figure 2 is a sectional view of the preferred form pipe coupling of Figure 1 in which the interior gripping surface of the die ring of the coupling comprises a thread of reverse hand, when assembled ready for use and into which a pipe end has been inserted;

Figure 3 is a sectional view of the preferred form pipe coupling of Figure 1 similar to that of Figure 2 but showing the coupling when the pipe end is fully coupled;

Figure 4 is a sectional view of the pipe coupling of Figures 1 to 3 when the clamp nut has been loosened just prior to the withdrawal of the pipe;

Figure 5 is a sectional view similar to that of Figure 2 of another preferred form pipe coupling which the gripping surface of the die ring comprises ribs; Figure 6 is a sectional view similar to that of Figure 3 but of the preferred form pipe coupling of Figure 5; and

Figure 7 is a sectional view similar to Figure 4 but of the second preferred form pipe coupling of Figure 5.

DETAILED DESCRIPTION OF PREFERRED FORMS

Referring to Figures 1 to 4, the preferred form pipe coupling shown includes a cylindrical body portion 1 having an internal bore 4, and which is provided with an annular flange 2. A portion of the bore 4 is provided with a screw thread 3 adjacent the flange 2 for securing the coupling to a pump inlet or outlet fitting or similar so that the coupling may then be used to couple a pipe to the pump or similar. As can be seen in Figures 2, 3 and 4, the bore 4 is stepped to form an area of larger diameter with the junction between the different diameter parts of the bore 4 being provided with a sealing seat 6.

As shown in Figure 1 , in the preferred form coupling a clamp nut 30 is hexagonally shaped as at 31 on its exterior wall so that it can be tightened by a spanner, but alternatively the exterior of the clamp nut 30 may be shaped to be hand gripped. The interior of the clamp nut 30 as shown in Figures 2, 3 and 4 has a leading part and which is screw threaded at 18 so that the clamp nut 30 can be engaged on the screw threaded portion 7 of the main body 1 of the coupling. The bore of the trailing portion of the clamp nut 30 is of reducing diameter towards the rear end of the clamp nut 30 and is provided with a series of longitudinal teeth 33. The pipe coupling also includes a die ring 20 which is also preferably formed from a plastics material and which has a bore 21 of substantially the same diameter as the sealing ring 10. The die ring 20 has a gripping interior surface. In the coupling of Figures 2 to 4 the interior gripping surface of the die ring 20 comprises a thread of a reverse hand to the thread between the clamp nut 30 and the body position 1 of the coupling. As shown in the drawings, the interior wall of the die ring 20 is screw threaded as at 23, but the screw thread is a left hand thread. A series of swarf clearance slots 24 are preferably formed in the interior wall of the die ring 20 as indicated particularly in Figure 1. The die ring 20 is split longitudinally and one preferred method of achieving this is indicated at 25 in Figure 1. While the actual form of the split 25 can vary to suit particular circumstances it is preferable that the construction be such that the die ring 20 can expand radially and retain its circular integrity. The exterior wall of the die ring 20 is tapered as shown in the drawings and is provided with a longitudinal rib or ribs 26 which will mate with the longitudinal teeth or splines 33 formed in the bore 32 of the clamp nut 30 as will be further described^

The outer wall of the die ring 20 and the tapered portion of the clamp nut 30 are of a complementary shape so that the die ring 20 can engage in the clamp nut 30 and the teeth or splines 33 on the interior of the clamp nut 30 can engage in the ribs 26 on the exterior of the die ring 20. Therefore when the grab ring 20 has been engaged within the clamp nut 30, the die ring 20 can move longitudinally within the tapered portion of the bore of the clamp nut 30. During such movement the diameter of the die ring 20 will either increase or decrease, depending upon the position of the die ring 20 within the clamp nut 30. Preferably the die ring 20 is made of a resilient material with a plastic "memory" so that in its relaxed state it will assume a position of maximum diameter. A sealing ring 10 which may be formed from a deformable plastics material has end faces, each of which is provided with a groove 1 1 which is substantially complementary in shape to the sealing seat 6, so that when the coupling is assembled as shown in Figure 3, the groove 1 1 on one face of the sealing ring 10 will engage with the sealing seat 6 to form a fluid tight seal. When assembled, the groove 1 1 in the other end face of the sealing ring 10 will mate with a similarly shaped end face of a pusher ring 15 which can be seen from the drawings has internal and external diameters substantially similar to the sealing ring 10.

The sealing ring 10 has sealing lips 17 at both ends of the seal on both the bore and the external diameters. These sealing lips 17 can have the same or dissimilar configurations and shapes dependent upon the service requirements of the pipe coupling.

In operation, the pipe coupling is assembled as shown in Figure 2 and a pipe end 40 is entered into the coupling and through the bore of the clamp nut 30, the die ring 20, the pusher ring 15 and the sealing ring 10 and into the bore 4 of the main body 1 of the pipe coupling. As can be seen from Figures 1 , 2 and 3, the bore 4 of the mam body 1 of the pipe coupling is provided with a series of ribs 8 or similar which will engage with the wall of the pipe end 40 and which will tend to resist rotation of the pipe 40 within the bore 4 of the main body 1 of the pipe coupling. The clamp nut 30 is then rotated so it will advance on the main body 1 of the pipe fitting by means of the screw threads 7 and 18. This action will cause the teeth or splines 26 on the die ring 20 to engage the teeth or splines 33 in the clamp nut 30. Once engaged further rotating the clamp nut 30 will also rotate the die ring 20 in the same direction in relation to the pipe 40 but because the thread 23 in the bore of the die ring 20 is a reverse thread, the die ring 20 will tend to cut a number of threads or grooves concurrently in a direction opposite to that of the clamp nut 30 and during such movement, because of the complementary tapers of the outside of the die ring 20 and the interior of the clamp nut 30, the bore 21 of the die ring 20 will be decreased from that shown in Figure 2 to that indicated in Figure 3. This will force the cutting threads 23 against the outside of the pipe end 40 and therefore tend to concurrently cut a number of reverse threads or grooves in the outside wall of the pipe. During this action the material removed in cutting the threads will be contained in the slots 24 in the die ring 20. Also during this action, the pipe end 40 will be retained against possible rotation by reason of the ribs 8 or similar within the bore 4 of the main body 1 of the pipe coupling engaging on the wall or the end of the pipe end 40.

Preferably the threads on the interior of the die ring 20 are of a finer pitch than the thread between the clamp nut 30 and the body portion 1 of the coupling, so that the clamp nut 30 will move onto the body portion of the coupling as it is rotated at a greater rate than that at which the die ring 20 is forced to move rearwardly within the clamp nut. This has been found to give a more reliable operation of the coupling.

When the die ring 20 has moved as far as possible towards the small end of the interior of the clamp nut 30, further rotation of the clamp nut 30 will result in the combined die ring 20 and the pipe end 40 moving into the bore 4 of the mam body 1 of the pipe coupling, this movement being facilitated by the ribs 8 or similar. When the clamp nut 30 has been screwed home, the pusher ring 15 will compress the sealing ring 10 which will therefore complete a seal between the exterior wall of the pipe end 40 and the pipe coupling. The lips 17 on the sealing ring 10 will move to contact the exterior wall of the pipe end 40 on the inside of the seal and the bore 4 of the main body 1 of the pipe coupling when the pusher ring 15 compresses the sealing ring 10 between itself and the internal groove 6 in the main body 1 of the pipe coupling. The shape and configuration of these lips 17 will vary dependent upon the service requirements of the pipe coupling.

Referring to Figures 5 to 7, the second preferred form pipe coupling shown is identical to that of Figures 2 to 4 except that the interior of the die ring 20 comprises a ribbed gripping surface. The gripping surface comprises a number of adjacent ribs as shown. Otherwise in Figures 5 to 7 the same reference numerals indicate the same components as in the coupling of Figures 2 to 4. In the coupling of Figures 5 to 7, as the clamp nut 30 is rotated and advances on the main body 1 of the coupling by means of the screw thread 7 and 18, the die ring 20 will be simultaneously rotated around the pipe end and closed about the pipe end, so that the ribs around the interior of the die ring forming the gripping surface will clamp into the surface of the pipe end. Again, when the die ring 20 has moved as far as possible towards the small end of the interior of the clamp nut 30, further rotation of the clamp nut 30 will result in the combined die ring 20 and the pipe end 40 moving into the bore 4 of the main body 1 of the coupling so that the pusher ring 15 will compress the sealing ring 10 to complete a seal between the exterior wall of the pipe end 40 and the pipe coupling.

As referred to previously, in a further form of the pipe coupling the interior of the die ring may be provided with threads of a similar hand to the thread between the clamp nut 30 and the body portion of the coupling. Further again, the interior of the die ring may comprise a knurled or cross-hatched or a roughened surface to form a gripping surface which will effectively clamp around the pipe end in use, instead of being threaded or ribbed.

The foregoing describes preferred forms of coupling of the invention for coupling a pipe to a piece of equipment such as a pump. Pipe couplings of the invention can be configured to couple two pipes end to end or to couple pipes as an elbow joint or as a T joint. Other modifications and changes can be made to the specific forms described still within the scope of the invention.

Claims

1. A pipe coupling comprising a body part having a hollow interior, a clamp nut also having a hollow interior and comprising a screw threaded part by which the clamp nut is threaded coaxially onto the body part of the coupling and a part which is tapered with a diameter which reduces towards an end of the clamp nut opposite the threaded interior part, and a die ring positioned within the tapered portion of the clamp nut and having a gripping interior surface and means connecting the die ring to the clamp nut so that the die ring will rotate with the clamp nut, such that on insertion of a pipe end through the clamp nut and the die nng within the clamp nut and into the body part of the coupling, rotation of the clamp nut to advance the clamp nut onto the body part will rotate the die ring to force the threaded interior of the die ring into contact with the exterior wall of the pipe to secure the pipe end in the coupling.

2. A pipe coupling according to claim 1 wherein the interior of the die ring is threaded with a thread of a hand opposite to the hand of the threaded interior part of the clamp nut, so that rotation of the clamp nut to advance the clamp nut onto the body part of the coupling will rotate the die ring to force the threaded interior of the die ring to close about the exterior wall of the pipe end and form a reverse thread, groove or circumferential or helical groove on the pipe end and move the die ring towards the entry end of the clamp nut.

3. A pipe coupling according to claim 1 wherein the interior of the die ring is provided with one or more ribs to form the gripping interior surface of the die ring, which will engage into the exterior wall of the pipe end as the clamp nut is rotated to advance the clamp nut.

4. A pipe coupling according to claim 2 wherein said thread of opposite hand on the interior of the clamp nut is of a finer pitch than the pitch of the thread between the clamp nut and the body part of the coupling so that the die ring will move rearwardly on the pipe at a slower rate than the clamp nut moves forwardly onto the body part of the coupling on rotation of the clamp nut.

5. A pipe coupling according to claim 1 wherein the interior of the die ring is threaded with a thread of the same hand as that between the clamp nut and the body part of the coupling.

6. A pipe coupling according to any one of the preceding claims wherein the die ring is split longitudinally to allow contraction and expansion of the die ring.

7. A pipe coupling according to any one of the preceding claims wherein the die ring is formed of a resilient plastics material.

8. A pipe coupling according to any one of the preceding claims including means to prevent the pipe end from rotating within the pipe coupling.

9. A pipe coupling according to any one of the preceding claims wherein the die ring includes a means to remove pipe material cut from the exterior pipe wall by the action of the rotating die ring such that said removed material does not interfere with the action of the die ring.

10. A pipe coupling according to any one of the preceding claims wherein the die ring includes a means of positively cutting a thread, groove or other shape into the exterior wall of the pipe.

1 1. A pipe coupling according to any one of the preceding claims including an end seal within the bore of the body part of the coupling which co-acts with a pusher ring capable of being compressed against the end seal when the clamp nut has been screwed home onto the body part.

12. A pipe coupling according to any one of the preceding claims including means to retain the die ring in the clamp nut while the clamp nut is being unscrewed.

13. A pipe coupling according to any one of the preceding claims wherein means are provided to ensure that the end seal is capable of sealing against both the exterior wall of the pipe and the bore of the body part.

14. A pipe coupling according to any one of the preceding claims wherein means are provided to ensure that the end seal is capable of maintaining both a pressure and/or a vacuum seal.