Method And Apparatus For Coupling Melt Conduits In A Molding System And/Or A Runner System

1 . An expansion bushing of a molding runner system, comprising:

a body having a portion configured to cooperate with a melt conduit, the body sealing against the melt conduit responsive to a thermal expansion of the body relative to the melt conduit.

2 . An expansion bushing according to claim 1 , wherein said body has an outer surface configured to contact inner surfaces of first and second melt conduits responsive to said thermal expansion.

3 . An expansion bushing according to claim 1 , wherein said body comprises an annular member having an inside diameter substantially equal to an inner diameter of the melt conduit.

4 . An expansion bushing according to claim 1 , wherein said body grows more per given temperature change than the melt conduit.

5 . An expansion bushing according to claim 4 , wherein said body comprises a cobalt-based alloy.

6 . An expansion bushing according to claim 5 , wherein said body is made of a different material than the melt conduit.

7 . A coupler coupling a first melt conduit and a second melt conduit, comprising:

an annular expansion bushing having a cylindrical outer surface configured to seal, upon application of heat to said bushing, with an inner cylindrical surface of the first melt conduit and an inner cylindrical surface of the second melt conduit; and

said annular expansion bushing having an inner cylindrical surface corresponding substantially to melt passageways of the first and second melt conduits.

8 . A coupler according to claim 7 , wherein said annular expansion bushing has a thermal expansion property which is greater than that of the first melt conduit and the second melt conduit.

9 . A coupler according to claim 7 , wherein said annular expansion bushing comprises a cobalt-based alloy.

10 . A coupler according to claim 7 , wherein said annular expansion bushing is made of a different material than the first and second melt conduits.

11 . A coupler according to claim 7 , further comprising:

external coupling structure having at least one surface configured to couple with outside surfaces of the first and melt conduits; and

cooling structure configured to provide a coolant to said external coupling structure.

12 . A melt conduit coupler, comprising:

a fist melt conduit having a first melt channel and a first bushing seat;

a second melt conduit having a second melt channel and a second bushing seat; and

an expansion coupler having (i) an outer surface configured to seal with the first bushing seat and the second bushing seat in response to thermal energy applied to said expansion coupler, and (ii) a melt channel having substantially the same diameter as the first melt channel and the second melt channel.

13 . A coupler according to claim 12 , wherein said expansion coupler has an annular outer surface and an annular melt channel.

14 . A coupler according to claim 12 , wherein said expansion coupler has a thermal expansion property which is greater than that of the first melt conduit and the second melt conduit.

15 . A coupler according to claim 12 , wherein said expansion coupler comprises a cobalt-based alloy.

16 . A coupler according to claim 12 , wherein said expansion coupler grows more per given temperature change than either melt conduit.

17 . A coupler according to claim 12 , wherein a cold clearance is provided between ends of the expansion coupler and corresponding ends of the first and second bushing seats.