AU677838B2

AU677838B2 - Pipe joint, pipe connector and hydraulic device for producing pipe joints

Info

Publication number: AU677838B2
Application number: AU64284/94A
Authority: AU
Inventors: Friedrich Imgram
Original assignee: WIRSBO ROHRPROD und VERTR GmbH
Current assignee: WIRSBO PEX GmbH
Priority date: 1993-03-27
Filing date: 1994-03-21
Publication date: 1997-05-08
Anticipated expiration: 2014-03-21
Also published as: HU219524B; ZA941769B; PL310885A1; JPH08508330A; DE4310000A1; KR960701331A; DK0694143T3; DE59405397D1; HUT72196A; SK115895A3; GR3026330T3; HU9502754D0; NO953810L; WO1994023237A1; NZ263554A; EP0694143A1; PL174049B1; IL109047A0; SK280978B6; CZ249695A3

Abstract

The pipe joint proposed includes a connector (1) with at least one spigot (2, 2', 2") on which the end (6) of a pipe made of thermoelastic, cross-linked polyolefin is fixed by opening out and self-reforming to form a secure, gastight joint. The spigots (2, 2', 2") have a surface feature (3, 3', 3") and, beyond it, an extension (4, 4', 4") with chamfered end (5, 5', 5").

Description

Amended Documents Presented During Examination Tube Conduit Connection, Tube Conduit Connector and Hydraulic Apparatus for Making Tube Conduit Connections The invention relates to a tube conduit connection containing a tube conduit connector having a connecting member which comprises a surface structure, and a tube end which has been expanded at ambient temperature and which is formed at the end of a tube which is self-reconvertable at ambient temperature, the tube end being firmly and sealingly connected to the connecting member.

The invention also relates to a tube conduit connector which contains at least one connecting member having a surface structure, for producing a firm and sealing connection to tube conduits which have a tube end expanded at ambient temperature and formed of a tube which is selfreconvertable at ambient temperature.

Finally, the invention also relates to a method of using a hydraulic pulling device for connecting a tube conduit connector to a tube end, which pulling device contains at least one hydraulic cylinder-piston unit, retaining means for respectively retaining a tube end or the tube conduit connector, movable retaining means for respectively retaining the tube conduit connector or the tube end, and a hydraulic pump connected to the at least one hydraulic cylinder-piston unit.

From published European Patent Application No. 0,530,387, there is known to produce firm and gas-tight tube conduit connections at ambient temperature using tubes made of a material like medium density, high density or thermoelastic, cross-linked polyolefins. Therefore, the tube end is reversibly expanded and applied to the connecting member of the tube conduit connector. An expanding mandrel is usually employed for this purpose. Even under these conditions, the material, particularly the thermo-elastic cross-linked polyolefin is subject to self-reconversion into the original condition. The self-reconversion is of sufficient rate also at ambient temperature in order to form a firm and gas-tight connection to the tube conduit connector after expansion. The firm and gas-tight connection therein is effected by means of a surface structure which is present at the connecting member of the tube conduit connector and about which the expanded tube end contracts due to the self-reconversion so that there is formed a large surface area, very tight connection between the tube end and the connecting member of the tube conduit connector.

From British Patent No. 773,033 there is known a tube connector which is connectable to an expanded end of a PVC tube. The tube connector contains a connecting member having a surface structure in the form of an annular expansion. A smooth tube-shaped end extends from the surface structure and carries a seal. The tube end of the PVC tube is heated until it is softened and, then, expanded by means of a mandrel which is pulled out from the expanded end after it has cooled. The tube connector is, then, inserted into the expanded tube end which subsequently is re-heated up to the softening temperature. During this operation, the expanded tube end re-contracts and is firmly and sealingly applied to the tube-shaped end which is provided with the seal, and the tube connector and its annular expansion.

From German Gebrauchsmuster (Utility Model) No. 89 14 321 there is known a hydraulic tube mounting apparatus containing a hydraulic cylinder and a double-acting piston.

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Each one of one end of the cylinder and the free end of the piston are respectively connected to tube retaining means for the tube ends of respective one of two tubes which are guided on rolls. One of the two tube ends is provided with a bushing or expansion and a bushing seal is located between the tube ends to be connected. The two tube ends are moved into each other by operating the hydraulic cylinder whereby a firm and sealing connection is produced due to the inserted bushing seal.

It has been found in practice that the initially mentioned tube conduit connections which are produced at ambient temperature using the expanding mandrel, can be produced with good success when using tube diameters in the range of 50 mm and above. With smaller diameters, there exists a problem in that such narrower tube conduit is relatively flexible and that the tube end eventually can become disconnected from the connecting member of the tube conduit connector to a small extent upon bending of the tube conduit. This small extent is sufficient for causing an undesired leak at the location of the connection.

In correspondence therewith it is the object of the invention to provide a tube conduit connection to the tube conduit connector which tube conduit connection is sufficiently tight even upon bending of the tube conduit, and to further provide a tube conduit connector which renders possible producing such sufficiently tight connection.

According to 17 th A-Invni this ebjeet is i respect to the tube conduit co 1::11-in that the connecting meqi]i :iriises an elongation in the form of a strc-C]~- clnril tube wich extends from the 3: Thus according to the present invention there is provided a tube conduit connection containing a tube conduit connector, which includes a connecting member having a surface structure, and further containing a tube end which has been expanded at ambient temperature and which is formed at the end of a tube which is seif-reconvertable at ambient temperature, the tube end being firmly and sealingly connected to the connecting member, characterised in that the connecting member comprises an elongation in the form of a structureless cylindrical tube which extends from the surface structure and forms the free end of the connecting member, said tube and said connecting member having substantially the same inner diameters and said end extending over the structureless cylindrical tube as well as over the surface structure provided at the connecting member.

With respect to the method of using the hydraulic pulling device, this 15 object is achieved in that this hydraulic pulling device is employed for producing the inventive tube conduit connection by means of the inventive tube conduit connector.

In this manner it is achieved that even tube ends of tubes having relatively small diameters can be applied to the connecting member of the respective tube conduit connector in a manner such that the tube conduit connection does not produce a leak under bending stress. Also the tube end containing the elongation is firmly and sealingly connected to the connecting member by using the hydraulic pulling device without any preceding deformation or the interposition of a seal.

It can be expedient that the outer diameter of the elongation can. be smaller than the outer diameter of the connecting member.

Advantageous further developments of the inventive tube conduit conmnection and tube conduit comnectors are characterised in the dependent claims.

Likewise it has been found in practice that the expansion of the tube end using an expanding mandrel may result in problems in the case of smaller tube diameters. It has been found that a hydraulic pulling device which is known as such for producing connections using plastic tubing can also be used with advantage for producing connections in the case of tubes which are made of relatively stiff materials such as thermo-elastic cross-linked polyolefin, particularly at ambient temperature and in a manner such that a firm and gas-tight connection is formed at ambient temperature due to the self-reconversion of the material.

Exemplary embodiments of the invention are illustrated in the drawings and will be explained and described h nr- nliol t~r -i i-n-.-ii 1 *v m n i- -hn o f r ni. -h.T r^ar There are shown in Figure 1 a sectional view of a tube coni t connection according to the invention; a Figure 2 a schematic view a hydraulic pulling device for producing e tube conduit connection as shown in Fia 1.

In the sectional view of Figure 1, there will be rrn 17cFrl a +-iht rTcnrim+11- e-r'nno.ccrt in l fh .rm P Ft'v--n rr -cnfnjzd atil- codlii rn -rt-r 1in -he for 4, L -C L _1 Lt hereinbelow in detail by means of the reference characters.

There are shown in Figure 1 a sectional view of a tube conduit connection according to the invention; and Figure 2 a schematic view of a hydraulic pulling device for producing the tube conduit connection shown in Figure 1.

In the sectional view of Figure i, there will be recognized a tube conduit connector 1 in the form of a Tpiece having three connecting members 2, and Each one of the connecting members 2, and 2" contains a respective surface structure in the form of a reinforcement 3, 3' and which may also be constructed as a groove or bead or the like. In the illustrated embodiment the reinforcements steeply descend inwardly to the outer diameter of the respective connecting member whereas the reinforcements taper outwardly to the free end. There is thus formed a structure which facilitates sliding on the tube end due to the ramp shape but which otherwise presents sufficient resistance against pulling off the applied tube end again due to the inner steep descent.

The reinforcements 3, and 3" are adjoined toward the exterior by respective elongations 4, and 4" which have the same inner diameter as the associated connecting members 2, and 2" but which may have, if desired, an outer diameter slightly reduced relative to that of the respective connecting member, as illustrated. The free end of the elongations 4, and 4" is provided with respective chamfers 5, and 5" in order to facilitate the introduction into the related tube end.

Identically formed tube ends 6 which are applied to the connecting members 2, and will be recognized at the respective connecting members 2, and In particular, these tube ends or tubes are designed such that their inner diameter is substantially equal to the inner diameter of the respective connecting members 2, and In this manner it will be avoided that edges are formed on the inside at the transition from the tube ends 6 to the respective connecting members which edges represent flow resistances to the throughflow of the medium respectively flowing therethrough. If such flow resistances are no object, other relative inner diameter relations can, of course, be selected.

In the illustrated exemplary embodiment, the tubes or tube ends 6 are made of thermo-elastic cross-linked polyolefin which is expanded at ambient temperature and applied to or pushed onto the respective connecting member 2, or 2" in the expanded condition. It will be recognized that the expanded tube end 6 will be tightly applied to the respective connecting member upon selfreconversion and thereby contracted around the respective reinforcement 4, and Due to the elongation 4, 4', and 4" the length of the connection will be increased and, due to the hold at the surface structure of the respective connecting member, there will be formed a large surface area connection, which remains firm and gas-tight even under bending stress effective at the associated tube.

As a result of the expanding operation, the tube conduit connection described hereinbefore may eventually still contain a reinforcement 20, see Figure 2, which is applied to the outside in the region adjacent the expanded tube end 6. Such reinforcement 20 may consist of an elastomeric, -3 5 thermoplastic or thermo-elastic material having higher t elasticity than the material of the tube, however, may also be made of the same material as the tube.

In the illustrated exemplary embodiment, the tube conduit connector 1 is constructed as a T-piece. Instead, the tube conduit connector 1 may have a Y-shape or may be differently shaped, for example, also as a simple tube connector having just two connecting members. In the most simple case, the connecting member may also be formed by a correspondingly constructed tube end in the event that a direct connection is intended to be formed between two tube ends. In the illustrated exemplary embodiment, the tube conduit connector consists of metal, particularly bronze; it may also consist of other materials like glass or plastic and also of thermo-elastic cross-linked polyolefin.

For producing the connection between a connecting member of the aforementioned type and a tube end, there may serve, for instance, a hydraulic pulling device as schematically illustrated in Figure 2; such pulling device is known as such for use in connection with plastic tubes. It has been found that this hydraulic pulling device can also be used with advantage for reversibly expanding at ambient temperatures the tube ends of tubes which are made of thermo-elastic cross-linked polyolefin.

Two hydraulic cylinders 7 and 8 will be recognized in Figure 2 and are arranged parallel to each other and bridged by first retaining means 9. The first retaining means 9 include a knurled screw 10 or the like at one of its ends and a hinge 11 at the other end. Two retaining members of the first retaining device 9 are interconnected by means of the hinge 11 such that the retaining members can be opened and receice a tube end 6 of a tube 12 therebetween and retain the same in the closed state.

From the hydraulic cylinders 7 and 8 respective piston rods 13 and 24 protrude and extend parallel to each other; free ends thereof are bridged by second retaining means The second retaining means also comprise hinge-connected retaining members between which a tube connector, for example, a tube connector 1, can be received and retained such that, as shown, a connecting member 2 protrudes from the second retaining means 15 towards the tube end 6.

A manually operable hydraulic pump 16 is connected through a hydraulic conduit 17 to connectors 18 and 19 at the respective hydraulic cylinders 7 and 8. It will be recognized that, upon actuating the hydraulic pump 16, the piston rods 13 and 14 are retracted into the respective hydraulic cylinders 7 and 8. As a result, the second retaining means 15 conjointly with the connecting member 2 is pulled towards the free tube end 6 and into the same.

There is directly obtained in this manner a firm and gastight connection between the connecting member 2 and the tube end 6.

For supporting the tube end 6 against deformation during the pulling-in operation of the connecting member 2, it is provided that the tube end 6 is surrounded by a reinforcement 20, which is made of an elastomeric, thermoplastic or thermo-elastic material, in the region which protrudes beyond the first retaining means 9 and which is not applied to the connecting member 2 or adjoins the tube end 6 which is intended to be expanded. The material of the reinforcement 20 may be more elastic than the material of the tube but may also be made of the same material. After expansion of the tube end 6, the reinforcement 20 may be removed or left to remain at the tube end 6.

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Claims

1. A tube conduit connection containing a tube conduit connector, which includes a connecting member having a surface structure, and further containing a tube end which has been expanded at ambient temperature and which is formed at the end of a tube which is seif-reconvertable at ambient temperature, the tube end being firmly and sealingly connected to the connecting member, characterise d in that the connecting member comprises anl elongation in the form of a st., octureless cylindrical tube which extends from the surface structure and forms the free end of the connecting memnber, said connecting member and said tube end having substantially the same inner diameter, and said tube end extending over the structureless cylindrical tube as well as over the surfacc structure provided at the connecting member.

2. The tube conduit connection according to claim 1, characterised in 15 that the elongation has anl outer diameter which is smaller than the outer diameter of the connecting member. t3.a The tube conduit connection according to claim 1 or 2, characterised in thtthe surface structure consists of a reinforcement which tapers towards the elongation and z'erges therewith.

4. The tube conduit connection according to claim 2 or 3, characterised 0: in that time free end of the elongation is chamfered. The tube conduit connection according to any one of claims 1 to 4, characterised in that the tube end has an inner diameter which is equal to the inner diameter of the connecting member.

6. The tube conduit connection according to any one of the preceding claims, characterised in that the tube conduit connector is selected from a tube connector, a multiple connector or a tube end.

7. The tube conduit connection according to any one of the preceding claims, characterised in that the tube is selected from medium density, high density or thermo-elastic cross-linked polyolefin.

8. The tube conduit connection according to any one of claims 1 to 7, characterised in that the tube is provided with a reinforcement adjacent the expanded tube end, which is connected to the connecting member, the reinforcement being made of an elastomeric material and surrounding the tube end, in the region adjacent to the and surrounding the tube end.

9. A tube conduit connector for producing a firm and sealing connection of a tube end which is expanded at ambient temperature and which is formed at a tube which is self-reconvertable at ambient temperature, the tube conduir. connector containing at least one connecting member having a surface structure comprising a reinforcement disposed on the connecting member and an elongation in the form of a structureless cylindrical tube which extends from the surface structure and defines a free end, the free end being chamfered, the elongation having an outer diameter which is smaller than the outer diameter of the connecting member whichi is 10 disposed on the opposite side of the surface structure from the elongation, said coniecting member and said tube end having substantially the same inner diameter, and said tube end extending over the shuctureless cylindrical tube as well as over the surface structure piovided at the connecting member, and wherein the reinforcement tapers towards the elongation and merges therewith. The tube conduit connector according to claim 9, characterised in .that the connector is selected from a tube connector, a multiple connector or a tube end.

11. A method of using a hydraulic pulling device for producing a tuoe conduit connection according to any one of claims I to 8 by attaching a tube conduit connector according to any one of claims 9 to 10 to a tube end, the device including at least one hydraulic cylinder-piston unit, retaining ans for a tube end or the tube conduit connector, respectively, movable rewxing means for respectively retaining the tube conduit connector or the tube end, and a hydraulic pump which is connected to the at least one hydraulic cylinder-piston unit, for connecting a tube which is made of a thermo-elastic cross-linked polyolefin, to the tube conduit connector,

12. The method of using the pulling device according to claim 11, characterised in that the end of the tube or the tube conduit connector, respectively, which end is to be hydraulically expanded, is provided with a reinforcement which is made of an elastomeric material, in a region adjacent the tube end to be expanded.

13. The method of using the pulling device according to claim 11 or 12, characterised in that the hydraulic cylinder-piston unit comprises a cylinder which includes a piston and an oil reservoir and which is connected to a manually operated pump, and that there are provided stationary retaining retaining means, which is guided in guide means, for the tube end or the tube connector, respectively.

14. The method of using the pulling device according to claim 11 or 12, characterised in that the pulling device includes two hydraulic cylinder- piston units each including a hydraulic cylinder and a piston rod, that the stationary retaining means bridges the two hydraulic cylinders which are arranged parallel to each other, and that the movable retaining means is attached to the piston rods which extend parallel to each other and protrude from the hydraulic cylinders. 10 15. A tube conduit connection as claimed in any one of claims 1 to 8 and substantially as hereinbefore described with reference to the drawings.

16. A tube conduit connection as claimed in any one of claims 9 to and substantially as hereinbefore described with reference to the drawings.

17. A method as claimed in any one of claims 11 to 14 and substantially as hereinbefore described with reference to the drawings. DATED this twenty-eighth day of February 1997 WIRSBO ROHRPRODUKTION UND VERTRIEBS-GMBH Patent Attorneys for the Applicant: F.B. RICE CO. i -9 Abstract Tube Conduit Connection, Tube Conduit Connector and Hydraulic Apparatus for Making Tube Conduit Connections The tube conduit connection contains a tube conduit connector including at least one connecting member and a tube end which is made of a thermo- elastic cross-linked polyolefin and which is firmly and gas-tightly applied to the connecting member by expansion and self-reconversion of the tube end. The connecting member contains a surface structure which is outwardly followed by an elongation having a chamfered end (Figure 1) K~ ~i i g i ~1 Pill