GB1561770A

GB1561770A - Method of joining tubes having a corugated wall

Info

Publication number: GB1561770A
Application number: GB38959/76A
Authority: GB
Original assignee: N Lundbergs Fabriks AB
Current assignee: N Lundbergs Fabriks AB
Priority date: 1975-09-25
Filing date: 1976-09-20
Publication date: 1980-03-05
Also published as: IL50538A0; AU509064B2; FI762714A; CH610081A5; JPS5260429A; FR2325875A1; IN146136B; DE2642283A1; AU1805976A; NO763283L; NL7610710A; JPS6015834B2; FR2325875B1; DK432176A; CA1054645A

Abstract

The internally located corrugation ridges of the outer wall (19) of the pipes are connected by means of an inner wall (11) which is smooth or is corrugated in an opposite manner. Two mutually adjacent pipes end axially against one another. As a result of this construction of both pipe ends in each case one annular space (15) is formed between the outer wall and the inner wall, into which a sealing ring (16) is inserted. A locking ring (17) which engages round the last corrugation ridge of the two pipes clamps the two pipe ends axially against one another. As a result of this construction of the pipe connection, the pipes require no special end construction, so that they can be cut to length as required. <IMAGE>

Description

(54) METHOD OF JOINING TUBES HAVING A CORRUGATED WALL (71) We, N. LUNDBERGS FABRIKS AB, a company duly organized and existing under the laws of Sweden, of Fristad, Sweden, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement.

The invention relates to a method of making a joint between tubes having a double wall structure comprising a corrugated outer wall and a smooth cylindrical or reversedly corrugated inner wall joining the inside crests of the outer wall, by means of a lock ring applied around the tube ends and engaging the corrugated outer wall of each tube.

An object of the invention is to provide a simple joint between tubes of the kind referred to wherein the specific characteristics of such tubes are utilized and which comprises a minimum of elements so that the joint will be of a simple structure and thus can be produced at low costs and can easily be mounted and demounted.

According to the invention, we provide a method of making a joint between two pieces of tubing each of which has a double wall of which the outer wall is annularly corrugated and the inner wall is either reversely annularly corrugated with the same pitch as that of the outer wall or is smooth cylindrical, the corrugations of the outer wall having inclined sides to the crests, each of the pieces to be joined having been cut through the crest of a corrugation so that there is an annular groove between the inner and outer walls at the cut end of the piece, which method comprises (a) placing the cut ends together with an annular sealing ring disposed in the aligned annular grooves, (b) placing around the cut ends a lock ring which has a channelled cross-sectional form the flanges of which are shaped to engage the inclined sides of the cut crests on each side of the joint, and (c) tightening the lock ring so as to press the tube ends axially towards each other by camming action whereby the sealing ring is caused to span the joint and provide a seal therein, and locking the lock ring in position.

The accompanying drawings illustrate an embodiment of the invention and, together with the description, serve to explain the principles of the invention.

In the drawings: Fig. 1 is a perspective view of a tube joint made according to the method of the invention; Fig. 2 is a view partly in elevational side view and partly in longitudinal sectional view of the tube joint; Fig. 3 is a cross-sectional view of the tube joint along line III-m in Fig. 2; Fig. 4 is a perspective view of the lock ring forming part of the joint, in opened or disengaged condition; and Fig. 5 is a perspective view of the lock ring in closed or engaged condition.

The two pipes joined are of a double wall structure of well-known type and comprise each a corrugated outer wall 10 (e.g.

of extruded and then in moulds vacuum formed plastics material), and a smooth cylindrical inner wall 11 (also of extruded plastics material), which is connected or fused to the inside crests of the corrugated outer wall at 12 so that the double wall structure comprises a number of circumferential annular spaces 13 each closed individually, and grooves 14 provided therebetween. In the embodiment illustrated, the corrugation of the outer wall is substantially of trapezoid cross-sectional form but other forms can be used, such as (a) one having a smoothly corrugated outer wall having substantially sinusoidal curvature or (b) a corrugated outer wall with an inner wall also corrugated, which is reversed in rela tion to the outer wall and the outside crests of which are connected or fused to the inside crests of the outer wall. In said latter case the corrugation of the inner wall must not necessarily follow that of the outer wall; however, the pitch of the inner wall should be the same as that of the outer wall.

Each tube end terminates in a plane which passes through a crest of the outer wall. However, it is not necessary that this plane passes through the centre of the crest if this crest, as shown, is of trapezoid crosssectional form and it is not necessary that it passes through the top of the crest if the corrugaion is sinusoidal or has a similar form. Terminating as described, each tube end forms an annular space 15 open at the end and defined between the outer and inner walls said space receiving a sealing ring 16 such as a ring of elastic material (e.g. rubber or plastics) which is received partly by the space in one tube end and partly by the space in the other tube end.

However, the tube ends are mutually spaced before they are clamped together as will be described below so that they can be pressed against each other, the sealing ring being squeezed between the tube ends. In the embodiment disclosed, sealing ring 16 is of substantially X-formed cross-sectional form, which is preferred since the arms of the profile are brought to seal effectively against the corners of spaces 15 receiving the sealing ring when the tube ends are pressed together.

The tube ends are pressed together by means of an external lock ring 17 which is disclosed in FIGS. 4 and 5 and comprises a slotted ring 18 (e.g. of plastics or metal) which is channelled in cross section and the flanges of which diverge towards the free ends thereof. At one side of the slot designated 19 the ring is formed with a hook 20 or other projection on the outside thereof close to the slot. At the other side of the slot there is connected to ring 18 by means of rivets 21 a straplike flap 22 of plastics or metal sheet. This flap is disposed on the outside of the ring and joins the ring substantially tangentially spaced about 90" from the slot. It projects freely from the ring towards the slot and beyond the adjacent end of the ring. For the major part thereof the flap is spaced from the ring but it is flexible towards and away from the ring. In the free end thereof, which has a greater width than the rest of the flap, the flap has a rectangular opening 23 which extends in the longitudinal direction of the flap and is sufficiently large to receive hook 20.

By further expansion of lock ring 17 from the condition disclosed in FIG. 4 the lock ring can be applied over the two tube ends transversely to receive the two terminating crests thereof which each form a space 15, between the flanges of ring 18.

Then, lock ring 17 is tightened circumferentially about the tube ends by means of pliers, a screwdriver or another suitable tool, and hook 20 is engaged with slot 23 in flap 22 so that the lock ring will be brought to the closed condition shown in FIGS. 1, 2, 3 and 5.

Sealing ring 16 should have such a width that the two terminating crests, when the sealing ring is not squeezed, are spaced a distance determined by the sealing ring, which allows the lock ring to be threaded transverseIy over the terminating crests at the outer ends of the ring flanges. Then, when the lock ring is being tightened about the tube ends as described the flanges of slotted ring 18, diverging towards the free ends thereof, slide along the inclined sides of the terminating crests so that the tube ends are moved axially towards each other by cam action between the tubes and the lock ring, the tubes being pressed against the sealing ring 16 which is squeezed and substantially fills the annular spaces 15, spanning the joint between the tubes to provide a seal therebetween.

By using a sealing ring and a lock ring there is thus provided a joint between the tubes by utilising the specific wall structure without the necessity to form the tubes in any specific way in the area of the joint.

The tubes can be cut at any place of the length thereof through a crest and can be joined according to the principles of the invention by using particularly simple means for obtaining the necessary seal between the tube ends.

WHAT WE CLAIM IS: 1. A method of making a joint between two pieces of tubing each of which has a double wall of which the outer wall is annularly corrugated and the inner wall is either reversely annularly corrugated with the same pitch as that of the outer wall or is smooth cylindrical, the corrugations of the outer wall having inclined sides to the crests, each of the pieces to be joined having been cut through the crest of a corrugation so that there is an annular groove between the inner and outer walls at the cut end of the piece, which method comprises (a) placing the cut ends together with an annular sealing ring disposed in the aligned annular grooves, (b) placing around the cut ends a lock ring which has a channeled cross-sectional form the flanges of which are shaped to engage the inclined sides of the cut crests on each side of the joint, and (c) tightening the lock ring so as to press the tube ends axially towards each other by camming action whereby the sealing ring is caused to span the joint and

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. tion to the outer wall and the outside crests of which are connected or fused to the inside crests of the outer wall. In said latter case the corrugation of the inner wall must not necessarily follow that of the outer wall; however, the pitch of the inner wall should be the same as that of the outer wall. Each tube end terminates in a plane which passes through a crest of the outer wall. However, it is not necessary that this plane passes through the centre of the crest if this crest, as shown, is of trapezoid crosssectional form and it is not necessary that it passes through the top of the crest if the corrugaion is sinusoidal or has a similar form. Terminating as described, each tube end forms an annular space 15 open at the end and defined between the outer and inner walls said space receiving a sealing ring 16 such as a ring of elastic material (e.g. rubber or plastics) which is received partly by the space in one tube end and partly by the space in the other tube end. However, the tube ends are mutually spaced before they are clamped together as will be described below so that they can be pressed against each other, the sealing ring being squeezed between the tube ends. In the embodiment disclosed, sealing ring 16 is of substantially X-formed cross-sectional form, which is preferred since the arms of the profile are brought to seal effectively against the corners of spaces 15 receiving the sealing ring when the tube ends are pressed together. The tube ends are pressed together by means of an external lock ring 17 which is disclosed in FIGS. 4 and 5 and comprises a slotted ring 18 (e.g. of plastics or metal) which is channelled in cross section and the flanges of which diverge towards the free ends thereof. At one side of the slot designated 19 the ring is formed with a hook 20 or other projection on the outside thereof close to the slot. At the other side of the slot there is connected to ring 18 by means of rivets 21 a straplike flap 22 of plastics or metal sheet. This flap is disposed on the outside of the ring and joins the ring substantially tangentially spaced about 90" from the slot. It projects freely from the ring towards the slot and beyond the adjacent end of the ring. For the major part thereof the flap is spaced from the ring but it is flexible towards and away from the ring. In the free end thereof, which has a greater width than the rest of the flap, the flap has a rectangular opening 23 which extends in the longitudinal direction of the flap and is sufficiently large to receive hook 20. By further expansion of lock ring 17 from the condition disclosed in FIG. 4 the lock ring can be applied over the two tube ends transversely to receive the two terminating crests thereof which each form a space 15, between the flanges of ring 18. Then, lock ring 17 is tightened circumferentially about the tube ends by means of pliers, a screwdriver or another suitable tool, and hook 20 is engaged with slot 23 in flap 22 so that the lock ring will be brought to the closed condition shown in FIGS. 1, 2, 3 and 5. Sealing ring 16 should have such a width that the two terminating crests, when the sealing ring is not squeezed, are spaced a distance determined by the sealing ring, which allows the lock ring to be threaded transverseIy over the terminating crests at the outer ends of the ring flanges. Then, when the lock ring is being tightened about the tube ends as described the flanges of slotted ring 18, diverging towards the free ends thereof, slide along the inclined sides of the terminating crests so that the tube ends are moved axially towards each other by cam action between the tubes and the lock ring, the tubes being pressed against the sealing ring 16 which is squeezed and substantially fills the annular spaces 15, spanning the joint between the tubes to provide a seal therebetween. By using a sealing ring and a lock ring there is thus provided a joint between the tubes by utilising the specific wall structure without the necessity to form the tubes in any specific way in the area of the joint. The tubes can be cut at any place of the length thereof through a crest and can be joined according to the principles of the invention by using particularly simple means for obtaining the necessary seal between the tube ends. WHAT WE CLAIM IS:

1. A method of making a joint between two pieces of tubing each of which has a double wall of which the outer wall is annularly corrugated and the inner wall is either reversely annularly corrugated with the same pitch as that of the outer wall or is smooth cylindrical, the corrugations of the outer wall having inclined sides to the crests, each of the pieces to be joined having been cut through the crest of a corrugation so that there is an annular groove between the inner and outer walls at the cut end of the piece, which method comprises (a) placing the cut ends together with an annular sealing ring disposed in the aligned annular grooves, (b) placing around the cut ends a lock ring which has a channeled cross-sectional form the flanges of which are shaped to engage the inclined sides of the cut crests on each side of the joint, and (c) tightening the lock ring so as to press the tube ends axially towards each other by camming action whereby the sealing ring is caused to span the joint and

provide a seal therein, and locking the lock ring in position.

2. A method as claimed in Claim 1, wherein the corrugations in the outer wall are of substantially trapezoid cross-section.

3. A method as claimed in Claim 1 or 2, wherein the sealing ring is of substantially X-shaped cross-section.

4. A method as claimed in Claim 1, 2 or 3, wherein the lock ring includes as locking means a flexible strap attached by one end to the outside of the ring and having in its other end an aperture for engagement with a projection on the outside of the ring.

5. A method as claimed in Claim 4, wherein said projection is spaced approximately 90" angularly from the attachment of the strap to the ring.

6. A method of making a joint as claimed in Claim 1 and substantially as hereinbefore described with reference to or as shown in the accompanying drawings.

7. A joint when made by a method as claimed in any preceding Claim.