Tube couplings

In a tube coupling of the kind comprising a body member with a bore having an axially tapered portion, a collet having arms extending into said portion of the bore, the tapered portion being such that axially outward movement of the collet arms engaging the tapered portion causes the collet arms to be pressed inwardly for gripping a tube in the bore, the body member is formed of inner and outer parts, at least the inner part being of plastics material which is, by ultrasonic vibrations, caused to enter into recesses, grooves, serrations or the like in an outer part.

I claim:

1. A method of making a tube coupling, wherein said method comprises

providing an outer part having a bore for receiving a tube, wherein the outer part comprises a first end through which the bore passes, a step in the bore facing and spaced from the first end, and axially spaced annular recesses encircling the bore between the step and the first end;

providing an annular molded plastics inner part having a head portion, and insert portion with an end face, and an opening through the inner part having an axially tapered inner annulus, wherein the molded plastics part has an outer surface tapering toward the end face between the head portion and the end face;

inserting the molded plastics inner part in the bore of the outer part so that the head portion of the inner part overlies and abuts the first end of the outer part, the end face of the inner part abuts the step in the bore of the outer part, and the tapered outer surface of the inner part overlies the recesses in the bore;

applying ultrasonic vibration to soften or melt the plastics material of the inner part to deform the outer tapered surface of the plastics part into the annular recesses in the bore of the outer part;

hardening the plastics material to form a locking engagement between the inner part and recesses of the outer part;

providing a collet having arms; and

inserting the arms of the collet into said tapered inner annulus of the plastics part, wherein the tapered portion is such that axially outward movement of the collet arms results in the collet arms engaging the inner tapered annulus thereby causing the collet arms to be pressed inwardly for gripping a tube in the bore.

2. A method as claimed in claim 1 wherein the outer part is of metal.

3. A method as claimed in claim 1 wherein the outer part is of plastics material.

4. A method as claimed in claim 1 wherein a further plastics bush or lining is ultrasonically welded into another part of the bore in the outer metal part.

5. A method of making a tube coupling, wherein said method comprises

providing an outer part having a bore for receiving a tube, wherein the outer part comprises a first end through which the bore passes, a step in the bore facing and spaced from the first end, and axially spaced annular recesses encircling the bore between the step and the first end;

providing an annular molded plastics inner part having a head portion, an insert portion with an end face, and an opening through the inner part having an axially tapered inner annulus, wherein the molded plastics part has an outer surface tapering toward the end face between the head portion and the end face;

inserting the molded plastics inner part in the bore of the outer part so that the head portion of the inner part overlies and abuts the first end of the outer part, the end face of the inner part abuts the step in the bore of the outer part, and the tapered outer surface of the inner part overlies the recesses in the bore;

providing a collet having arms;

inserting the arms of the collet into said tapered inner annulus of the plastics part, wherein the tapered portion is such that axially outward movement of the collet arms results in the collet arms engaging the inner tapered annulus thereby causing the collet arms to be pressed inwardly for gripping a tube in the bore;

applying ultrasonic vibration to soften or melt the plastics material of the inner part to deform the outer tapered surface of the plastics part into the annular recesses in the bore of the outer part; and

hardening the plastics material to form a locking engagement between the inner part and recesses of the outer part.

6. A method as claimed in claim 5 wherein the outer part is comprised of metal.

7. A method as claimed in claim 5 wherein the outer part is comprised of plastics material.

8. A method as claimed in claim 6 wherein a plastics lining is ultrasonically welded into another part of the bore in the outer metal part.