TUBE JOINT

Abstract: The invention relates to a joint for connection of two tubes (1, 20) to each other, especially tubes of a relatively soft plastic material, the one tube (1) in its one end having a male part (2) and the other tube (20) in its one end having a female part (22), the male part (2) and the female part (22) being brought into engagement with each other. The male part (2) has externally at least two oblique shoulders of engagement (3, 4). The female part (22) has internally at least two oblique shoulders of engagement (23, 24). The oblique shoulders of engagement (3, 4) of the male part come into contact with the oblique shoulders of engagement (23, 24) of the female part (22) when one strives to pull the mounted tubes (1, 20) apart. The mounted tube joint allows a limited axial movability between the tubes (1, 20) by the fact that there are a cavity (40) and two gaps (41, 42). The tube joint has a very good resistance against separation by pulling and it is very resistant against bending load and compression.

Description: Tube joint This invention relates to a joint for connection of two tubes to each other, especially tubes of a relatively soft plastic material, the one tube in its one end having a male part and the second tube in its one end having a female part, the male part and the female part being brought into engagement with each other. There is a great problem to bring about a joint between tubes of relatively soft material, for instance plastic material, which joint has a good resistance against among other things separation by pulling. There is a need of such tube joints for instance when relining leaking or defect tube lines, a new tube line being inserted into the damaged tube line. The object of the present invention is to provide an exceptionally attractive tube joint which is very suitable for joining tubes of relatively soft material. This object is achieved by the fact that the tube joint has the characterizing features mentioned in the claims. Besides the eminent resistance of the tube joint against separation by pulling, it may also be mentioned that the joint is very resistant against bending load and compression. Embodiments of the invention will be more closely described in the following with reference to the accompanying drawings in which fig 1 shows a longitu¬ dinal section through a tube joint according to the invention and fig 2 shows a longitudinal section through a further embodiment of the tube oint according to the invention. In fig 1 there is shown a tube joint between two tubes 1 and 20, the centre line of the tubes being denoted by C. The tube 1 has in its one end a male part 2 which is externally provided with two obligue or undercut shoulders of engagement 3 and 4. Furthermore, the male part 2 has four cylindrical platforms 5-8. Between the platforms 6 and 7 there is an obligue transition surface 9. The free end surface of the male part 2 is denoted by 10. The obligue shoulders of engagement 3 and 4 of the male part 2 form an acute angle ( < 90°) with the adjacent platforms 5,6 and 7,8, respectively. As a not limiting example of the size of this angle can be mentioned for instance 45°. The male part 2 has on its external platform 5 a groove 11 going round the male part for a gasket ring, for instance an O-ring (not shown). The tube 20 has in its one end a female part 22 which internally has two obligue or undercut shoulders of engagement 23 and 24. Furthermore the female part 22 has four cylindrical platforms 25-28. Between the platforms 25 and 27 there is an obligue transition surface 29. The obligue shoulders of engagement 23 and 24 of the female part form an acute angle ( t 90°) for instance 45° with the adjacent platforms 25,26 and 27,28, respectively. The free end surface of the female part 22 is denoted by 30. The mounting of the tubes 1 and 20 is made in that way that the male part 2 and the female part 22 are brought into engagement with each other, the elasticity of the tubes making it possible for the tubes to be brought together to the engagement position shown in fig 1, in which ttie shoulders of engagement 4,23 and 3,24, respectively, can come into contact with each other which happens when, after completed mounting, one strives to pull the mounted tubes apart. When the obligue shoulders of engagement come into contact with each other there is a cavity 40 which is limited by the obligue transition surfaces 9 and 29 and portions of the platforms 6 and 26. Furthermore, there is a gap 41 at the end surface 30 of the female part 22 and a gap 42 at the end surface 10 of the male part 2. The size of the cavity 40 and the gaps 41,42 is reduced when one strives to push the mounted tubes further together at the same time as the contact between the obligue shoulders of engagement of the male parts and the female parts is temporarily broken. It should be understood from what has been mentioned just now that the tube joint according to the invention offers a limited axial movability which among other things makes possible to take up for instance length changes of the mounted tubes. In the embodiment according to fig 2 the male part 2 of the tube 1 has two ring gaskets 11 and 12, respectively, for a gasket ring, for instance an 0-ring (not shown). The number of gasket rings can of course be varied in addition to what has been shown here. It should be understood that the number; of obligue or undercut shoulders of engagement of the male part and female part, respectively, can of course be more than two within the scope of the invention. In the shown embodiments the platforms 7 and 26 have a somewhat larger diametre than have the platforms 5 and 28, but all these platforms can of course have the same diametre measure. It should be mentioned that the length measure of the platform 25 suitably should be so great that..there will be no room for the platform in the recess which is limited by the surfaces 9,6 and 3, since this should lead to a more difficult mounting of the tube joint. Furthermore, it should be mentioned that it is possible for instance also to choose the diametre measures of the male part and the female part in that way that the female part 22 is forced to a certain diametrical elongation also after a completed mounting of the tube oint. The invention is not limited to what has been shown and described but changes and modifications of the invention is possible within the scope of the following claims.

Claims: Claims 1. A joint for connection of two tubes (1,20) to each other, especially tubes of a relatively soft plastic material, the one tube (1) in its one end having a male part (2) and the other tube (20) in its one end having a female part (22), the male part (2) and the female part (22) being brought into engagement with each other, c h a r a c t e r i z e d in that the male part (2) externally has at least two obligue shoulders of engagement (3,4), that the female part (22) internally has at least two obligue shoulders of engagement (23,24), and that the obligue shoulders of engagement (3,4) of the male part (2) come into contact with the obligue shoulders of engagement (23,24) of the female part (22) when one strives to pull the mounted tubes (1,20) apart. 2. A tube joint according to claim 1, c h a ¬ r a c t e r i z e d in that the obligue shoulders of engagement (3,4) of the male part (2) form an acute angle with the adjacent platforms (5,6 and 7,8, respectively). 3. A tube joint according to claim 1 or 2, c h a r a c t e r i z e d in that the obligue shoulders of engagement (23,24) of the female part (22) form an acute angle with adjacent platforms (25,26 and 27,28, respectively). 4. A tube joint according to anyone of the claims 1-3, c h a r a c t e r i z e d in that the mounted tube joint allows—a limited axial movability between the tubes (1,20) by the fact that there is a cavity (40) in an area between the shoulders of engagement (4,23 and 3,24, respectively) coming into contact with each other and by the fact that there are gaps (41,42) at the end surfaces (10 and 30, respectively) of the male part (2) and the female part (22), the size of the cavity (40) and the gaps (41,42) being reduced when the mounreα runes (.1,20) are further pushed together at the same time as the contact between the shoulders of engagement (3,4 and 23,24, respectively) of the male part (2) and the female part (22) is temporarily broken. 5. A tube joint according to anyone of the claims 1-4, c h a r a c t e r i z e d in that the male part (2) has at least one ring groove (11) for a gasket ring.

Inventors: PERSSON SUNE, PERSSON, SUNE
Applicants: RINTUV HB
Application year: 1988
Main classification: F16L47
IPC codes: F16L27, F16L31, F16L47