Gas assisted injection molding apparatus utilizing sleeve and pin arrangement

- Nitrojection Corporation

An apparatus for use in fluid assisted injection molding of plastic material so as to form an injection molded product includes a pair of mold members defining when closed the sealed cavity, a first opening provided in one of the mold members for allowing the injection of plastic material into the cavity and the second opening provided in one of the mold members, and spaced from the first opening, for allowing the injection of the fluid into the cavity. A sleeve extends through the second opening. The sleeve has a longitudinally extending bore with an open first end. Preferably, the sleeve is rigidly secured in relation to the one of the mold members through which it extends. A pin extends through the sleeve with the pin having a first end, located adjacent the sleeve first end, and a second end. Preferably the pin in rigidly secured in relation to the sleeve. A fluid flow passage is defined between the pin and the sleeve. In another embodiment, the fluid flow passage is defined between a tube and a pin. The tube is secured at one end to a bushing body. The busing is, in turn, positioned between a nozzle of an injection molding machine and a sprue of a mold cavity. In yet another embodiment, the pin is allowed to reciprocate in relation to the sleeve so as to selectively open and close a fluid flow passage defined between the pin and the sleeve.

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Claims

2. The apparatus of claim 1 further comprising a nozzle body positioned adjacent one of said mold body members.

3. The apparatus of claim 1 wherein said sleeve includes a first end which extends past a wall of said one of said mold members.

4. The apparatus of claim 1 wherein said longitudinally extending bore of said sleeve has a substantially constant diameter at and adjacent a sleeve first end.

6. The apparatus of claim 1 wherein said pin includes a first end located substantially even with a sleeve first end.

8. The apparatus of claim 1 wherein said flow passage defined between said pin and said sleeve element is substantially constant in area.

9. The apparatus of claim 5 wherein said support base comprises a fluid passage which communicates with said flow passage defined between said pin and said sleeve.

10. The apparatus of claim 7 wherein said sleeve second end comprises a threaded portion and said support base comprises a threaded bore in which said sleeve threaded portion is engaged.

11. The apparatus of claim 1 wherein said pin comprises a right cylinder having a substantially constant diameter.

12. The apparatus of claim 1 wherein said sleeve first end is so positioned in relation to said one of said mold members as to be even with a mold cavity wall of said one of said mold members.

13. A bushing for an injection molding machine and positioned between a nozzle thereof and a sprue of a mold, comprising:

a body having a longitudinal axis, a front end, a rear end and an exterior periphery:
a first bore which extends parallel to said longitudinal axis from said rear end to said front end of said body for accommodating a first fluid;
a bridge extending transversely across said first bore between opposing walls of said bore adjacent said body first end, fluid flow being allowed in said first bore around said bridge;
a second bore which extends in said bridge and in said body for accommodating a second fluid, said second bore terminating adjacent said body front end;
a sleeve having a first end and a second end, said sleeve first end being secured to said body front end and said sleeve extending away therefrom such that said sleeve second end is located forwardly of said body, said sleeve having a through bore which is in fluid communication with said second bore;
a pin extending longitudinally in said sleeve through bore; and,
a fluid flow passage defined between said sleeve and said pin.

14. The bushing of claim 13 wherein said pin has a first end secured to said bridge and a second end, said pin second end being approximately even with said tube second end.

15. The bushing of claim 13 wherein said pin comprises a right cylinder having a substantially constant diameter.

16. The bushing of claim 13 further comprising an outer sleeve having a first end, secured to said body first end, and a second end, said sleeve extending away from said body first end in a direction coaxial with said sleeve and encircling said sleeve.

17. The bushing of claim 13 wherein said flow passage defined between said pin and said sleeve element is substantially constant in area.

18. The bushing of claim 13 wherein said through bore of said sleeve has a substantially constant diameter at and adjacent said sleeve second end.

19. The bushing of claim 13 wherein said sleeve and said pin extend into a bore of the sprue of the mold.

20. The bushing of claim 13 further comprising fastening means for securing said bushing to one of the nozzle of the injection molding machine and the sprue of the mold.

21. An apparatus for injecting a molten thermoplastic material and a fluid, comprising:

a pair of mold members defining, when closed, a sealed cavity;
a first opening provided in one of said mold members for allowing the injection of a plastic material into said cavity;
a second opening provided in one of said mold members, and spaced from said first opening, for allowing the injection of a fluid into said cavity; and,
a fluid injection assembly disposed for reciprocating movement in said second opening in relation to said sealed cavity to control a flow of fluid into said cavity, said assembly comprising:
a pin,
a sleeve coaxial with said pin and encircling said pin, and
a fluid flow passage defined between said pin and said sleeve said pin and sleeve being fixedly secured in relation to each other.

22. The apparatus of claim 21 wherein said fluid injection assembly further comprises a base to which said pin and said sleeve are both rigidly secured, such that said pin and said sleeve do not move in relation to each other.

23. The apparatus of claim 22 further comprising a bore located in said base and in fluid communication at one end with said fluid flow passage.

24. The apparatus of claim 21 wherein said fluid injection assembly further comprises a selectively movable base, said pin being rigidly secured to said base and said sleeve being secured to said one of said mold members such that said pin moves in relation to said sleeve.

25. The apparatus of claim 24 wherein said base includes a bore which is in fluid communication at one end with said fluid flow passage.

26. The apparatus of claim 21 further comprising a means for reciprocating said fluid injection assembly.

27. The apparatus of claim 25 wherein said means for reciprocating comprises a piston and cylinder assembly..Iadd.

28. The apparatus of claim 1 further comprising a first means for rigidly securing said sleeve in relation to said one of said mold members..Iaddend..Iadd.29. The apparatus of claim 28 further comprising a second means for rigidly securing said pin in relation to said sleeve..Iaddend..Iadd.30. An apparatus for injecting a molten thermoplastic material and a fluid comprising:

a pair of mold members defining when closed, a sealed cavity and a runner;
a first opening provided in one of said mold members for allowing the injection of a plastic material into said runner and said cavity;
a second opening provided in one of said mold members and spaced from said first opening for allowing the injection of a fluid into at least one of said cavity and said runner; and,
a fluid injection and exhaust assembly disposed in said second opening to direct a flow of fluid into and out of said at least one of said cavity and said runner, said fluid injection and exhaust assembly comprising:
a pin,
a sleeve coaxial with said pin and encircling said pin, and
a fluid flow passage defined between said pin and said sleeve, wherein said fluid flow passage is open at all times during the operation of the apparatus..Iaddend..Iadd.31. The apparatus of claim 30 further comprising a second means for rigidly securing said pin in relation to said one of

said mold members..Iaddend..Iadd.32. The apparatus of claim 30 further comprising a second means for rigidly securing said pin in relation to said one of said mold members..Iaddend..Iadd.33. The apparatus of claim 30 wherein said flow passage defined between said pin and said sleeve is annular..Iaddend..Iadd.34. The apparatus of claim 30 wherein said pin comprises a right cylinder having a substantially constant diameter..Iaddend..Iadd.35. The apparatus of claim 30 wherein said sleeve comprises a reduced diameter bore section..Iaddend..Iadd.36. The apparatus of claim 30 wherein said pin comprises an increased diameter section..Iaddend.

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  • Machine Design article entitled "The Best of Two Worlds in Plastics Processing" (Dec. 9, 1982 issue) (4 pages).
Patent History
Patent number: RE35705
Type: Grant
Filed: Sep 21, 1995
Date of Patent: Dec 30, 1997
Assignee: Nitrojection Corporation (Chagrin Falls, OH)
Inventor: Jay F. Moldovanyi (Brecksville, OH)
Primary Examiner: Tim Heitbrink
Law Firm: Fay, Sharpe, Beall, Fagan, Minnich & McKee
Application Number: 8/531,430