COUPLING FITTING FOR PIPES

Abstract

The invention is directed to a coupling fitting, having a pipeline and having a connector sleeve. The pipeline and connector sleeve are each separate parts and are fixedly and non-detachably connected to one another by a connecting ring which can be produced in situ by injection molding plastics material. The invention is also directed to a method for making the coupling fitting.

Claims

1. A coupling fitting comprising: a pipeline having an inner diameter and defining an end and an outwardly directed radial annular bead disposed at a predetermined distance from said end; a connecting sleeve pushed onto said pipeline; said connecting sleeve having a first end disposed in the region of said annular bead and an inner wall surface defining a first inner diameter dimensioned so as to cause said annular bead and said inner wall surface to conjointly define a gap therebetween; said connecting sleeve further having a second end defining a second inner diameter which corresponds to said inner diameter of said pipeline; said radial annular bead and said end of said pipeline conjointly defining a transition zone wherein said first inner diameter transitions to said second inner diameter so as to permit said connecting sleeve to be pushed onto said pipeline only so far until said end of said pipeline does not fit any farther into said second diameter of said connecting sleeve; said end of said pipeline and said annular bead together with said coupling sleeve and said pipeline conjointly defining an annular cavity; an elastic annular seal disposed in said annular cavity; an injection molded connecting ring made of plastics material in an injection-molding process and being disposed in a region of said coupling fitting which is axially dimensioned so as to permit said connecting ring to cover over said first end of said connecting sleeve both in a first direction toward said second end of said connecting sleeve as well as in a second direction opposite said first direction to a predetermined dimension; and, the plastics material, because of injection pressure, extending through said gap into said annular cavity up to said elastic annular seal and extending from behind said annular bead in a direction away from said end of said pipeline so as to form a shoulder extending inwardly to said pipeline.

2. The coupling fitting of claim 1, wherein said connecting sleeve has at least one annular groove into which said plastics material of said connecting ring engages.

3. The coupling fitting of claim 1, wherein said coupling fitting further comprises a holder having a part thereof embedded in the plastics material of said connecting ring.

4. The coupling fitting of claim 3, wherein said part projecting into the plastics material of said connecting ring has at least one through hole which is filled with said plastics material.

5. A method of making a coupling fitting which includes a pipeline having an inner diameter and defining an end and a connecting sleeve, the method comprising the steps of: generating an annular bead on the pipeline disposed at a predetermined distance from the end of the pipeline; pushing an elastic annular seal onto the end of the pipeline so as to cause the annular seal to come to rest between the bead and the end of the pipeline; pushing the connecting sleeve having first and second ends onto the end of the pipeline until the first end comes to rest in the region of said bead so as to cause the outer diameter of the bead and a first inner diameter of the connecting sleeve to conjointly define a gap therebetween and the second end of said connecting sleeve having a second inner diameter corresponding to the inner diameter of the pipeline; the annular bead and the end of the pipeline conjointly defining a transition zone wherein the first inner diameter of said connecting sleeve transitions to the second inner diameter thereof so as to permit the connecting sleeve to be pushed onto the pipeline only so far until the end of the pipeline does not fit any farther into the second diameter of the connecting sleeve; and, injection molding the assembly composed of pipeline end and connecting sleeve to form a connecting ring of plastics material in a region which is axially dimensioned such that the connecting ring covers over the pushed-on first end of the connecting sleeve both in a first direction toward the second end of the connecting sleeve and in a second direction opposite the first direction by a predetermined dimension, wherein the plastics material of the connecting ring is, owing to the injection pressure, pressed through the gap as far as the elastic seal and, secondly, the injected material is pressed around the pipeline behind the bead in a direction away from the pipeline end, such that a shoulder is formed which extends inwardly to the pipeline.

6. The method of claim 5 comprising the further step of: arranging a holder in the region of the connecting ring to be injection molded, in such a way that a part of the holder projects into the region in which injection molding is to be performed, and said part is encapsulated by the injection-molded plastics material during the injection molding process.

7. The method of claim 6, wherein part of the holder which projects into the region in which injection molding is to be performed has at least one through hole into which the injection-molded plastics material ingresses during the injection molding process.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0034] The invention will now be described with reference to the single figure of the drawing (FIG. 1) which shows a coupling fitting according to the invention in longitudinal section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0035] In FIG. 1, the coupling fitting 1 has a pipeline 2 with an inner diameter 3 and has an end contour 4 and an encircling bead 5. The coupling 1 further includes a connector sleeve 6 with a first inner diameter 8 and a second inner diameter 7. The first inner diameter 8 is dimensioned such that a gap 9 exists between the encircling bead 5 and the connector sleeve 6. Between the end contour 4, the bead 5 and the inner diameter 8 of the connector sleeve 6, there is arranged an elastic ring seal 10 which seals off the pipeline 2 against the sleeve 6.

[0036] The sleeve 6 has an encircling groove 11 on its outer circumference. In the end region 12 of the sleeve 6, which end region is pushed onto the pipeline 2 over the bead 5, a connecting ring 13 composed of plastics material is injection-molded thereon. The connecting ring 13 completely covers the end region 12 of the sleeve 6 in an axial direction. The plastics material of the connecting ring 13 has, during the injection molding process, ingressed through the gap 9 into a cavity 14. The cavity 14 is formed by the elastic seal 10, the inner diameter 8 of the sleeve 6 and the pipeline 2. Owing to the injection-molding pressure, the seal 10 has been compressed slightly, which gives rise to an increase in the contact pressure of the seal 10 and thus an improvement of the sealing action. The connecting ring 13 furthermore engages around the outer circumference of the sleeve 6, wherein the material is also pressed into the groove 11. The connecting ring 13 furthermore extends around the end region 12 of the sleeve 6 such that, behind the end 12 of the sleeve 6 in the direction of the pipeline 2, the connecting ring 13 forms a shoulder 15 which extends as far as the pipeline 2. Here, the bead 5 is also enclosed or enveloped.

[0037] The connecting ring 13 thus prevents the inadvertent separation of sleeve 6 and pipeline 2 both in positively locking fashion, by engagement into the groove 11 and behind the bead 5, and by frictional engagement between the sleeve 6 and pipeline 2.

[0038] It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.

LIST OF REFERENCE SIGNS

Part of the Description

[0039] 1 Coupling fitting [0040] 2 Pipeline [0041] 3 Inner diameter of the pipeline 2 [0042] 4 End contour of the pipeline 2 [0043] 5 Encircling bead of the pipeline 2 [0044] 6 Connector sleeve/sleeve [0045] 7 Second inner diameter of the sleeve 6 [0046] 8 First inner diameter of the sleeve 6 [0047] 9 Gap [0048] 10 Elastic ring seal/seal [0049] 11 Encircling groove of the sleeve 6 [0050] 12 End region of the sleeve 6 [0051] 13 Connecting ring [0052] 14 Cavity [0053] 15 Shoulder of the sleeve 6