Injection molded cold-expansion compression collar
A compression collar is manufactured for use in reinforcing an interference fit between an end of a pipe and a fitting. A precursor form is injection molded using a cold-expansion material. The precursor form has a tubular body with an initially closed axial end and a bore that is initially blind formed in the other axial end. Material is removed from the initially closed axial end of the tubular body of the precursor form to form an opening in the initially closed axial end that connects to the bore thereby forming the compression collar. The opening has an inner periphery with a profile in axial cross section that is different than any profile in axial cross section of an inner periphery of the bore. The collar formed may lack knitlines and may include tabs formed during the removal step which help to position the collar on a pipe.
1. A compression collar for reinforcing an interference fit between an end of a pipe and a fitting, the compression collar comprising: an injection molded tubular body formed of a cold-expansion material, the tubular body having a pipe insertion end, the pipe insertion end including an insertion opening defined therein, a stop end opposite the pipe insertion end, the stop end including a stop opening defined therein, a central axis extending axially through the pipe insertion end and the stop end, a radially inner surface defining a bore extending along the central axis through the tubular body, the bore in fluid communication with the insertion opening and the stop opening, a radially outer surface spaced radially outwardly from the radially inner surface, at least one positioning tab positioned adjacent the stop end and extending radially inwardly toward the central axis, wherein the compression collar is structurally configured such that the compression collar is formed without and includes no knitlines, wherein each of the radially inner surface and the radially outer surface has a substantially constant radius with respect to the central axis between the pipe insertion end and the stop end such that the compression collar is a straight member.
2. The compression collar of claim 1 , wherein the cold-expansion material is at least one of polyolefin, cross-linked polyolefin, polyethylene, cross-linked polyethylene, PEX, PEX-a, PEX-b, PEX-c, and PERT.
3. The compression collar of claim 1 , wherein the compression collar includes no injection points from injection molding.
4. The compression collar of claim 1 , further comprising a chamfered edge defining a portion of the bore at the pipe insertion end.
5. The compression collar of claim 1 , further comprising a curved corner with a radius of curvature defining a portion of the bore at the pipe insertion end.
6. The compression collar of claim 1 , wherein the radially inner surface includes an injection molded radially inner surface.
7. The compression collar of claim 1 , wherein the radially outer surface includes an injection molded radially outer surface.
8. The compression collar of claim 1 , wherein the pipe insertion end is an injection molded pipe insertion end.
9. The compression collar of claim 1 , further comprising a wall thickness extending radially from the radially inner surface to the radially outer surface, the wall thickness being substantially constant along the axial direction of the tubular body.
10. The compression collar of claim 1 , wherein
the stop end includes a stop end outer face, the stop end outer face being an injection molded face, and
the stop opening is defined in the stop end outer face.
11. A compression collar for reinforcing an interference fit between an end of a pipe and a fitting, the compression collar comprising: an injection molded tubular body formed of a cold-expansion material, the tubular body having a first end including a first opening defined therein, a second end opposite the first end and including a second opening defined therein, a central axis extending axially through the first end and the second end along a length of the tubular body, a radially inner surface defining a bore extending along the central axis through the tubular body, a radially outer surface extending linearly along a majority of the length of the tubular body, and at least one positioning tab positioned adjacent the stop end and formed as a unitary part with the tubular body, the positioning tab extending radially inwardly toward the central axis, the positioning tab having an end face and a stop face opposite the end face, wherein the compression collar is structurally configured such that the compression collar is formed without and includes no knitlines, wherein each of the radially inner surface and the radially outer surface has a substantially constant radius along the central axis between the pipe insertion end and the stop end such that the compression collar is a straight member.
12. The compression collar of claim 11 , wherein the bore extending along the central axis through the tubular body is in fluid communication with the first opening and the second opening.
13. The compression collar of claim 12 , wherein
the radially inner surface further includes a plurality of flat surfaces,
each flat surface is separated from a circumferentially adjacent flat surface by a trough,
each flat surface extends along the axial direction of the tubular body such that the flat surfaces are configured to be tangent to a radially-outward facing surface of the pipe around which the compression collar is received.
14. The compression collar of claim 13 , wherein the second opening includes the at least one positioning tab, and the radially inner surface includes as many flat surfaces as there are positioning tabs.
15. The compression collar of claim 14 , wherein each flat surface has a width that is shorter than a width of a corresponding positioning tab.