Anti-backflow valve for injection molding machines
| Title: | Anti-backflow valve for injection molding machines |
|---|---|
| Patent Number: | 5,044,926 |
| Publication Date: | September 03, 1991 |
| Appl. No: | 07/542,988 |
| Application Filed: | June 25, 1990 |
| Abstract: | An anti-backflow valve for mounting on the forward end of a plasticating screw rotatably and translatably carried in a tubular barrel of an injection molding machine. The valve includes a rod-like body member that extends forwardly of the plasticating screw for rotation relative to the screw and for axial translation relative to the screw for a limited distance. A retaining sleeve is threadedly secured to the forward end of the screw to define a forward stop to limit axial outward movement of the body member relative to the screw. The outer surface of the retaining sleeve includes a valve seat that is engagable with a sealing surface on a screw tip that is carried at the forward end of the body member. The screw tip includes flow passageways extending substantially axially therethrough to provide communication between the space ahead of the screw and an area behind the screw tip and between the screw body and the screw-receiving tubular barrel. At least one sealing ring is carried by the body member and the retaining sleeve to prevent flow of plasticated material therebetween. The ability of the body member to rotate relative to the screw avoids breakage of the screw tip during a cold start-up condition when solidified plastic material from a previous operation of the machine surrounds the screw tip. |
| Inventors: | Dinerman, Alex (Cincinnati, OH); O'Bryan, James E. (Cincinnati, OH) |
| Assignees: | Cincinnati Milacron Inc. (Cincinnati, OH) |
| Claim: | What is claimed is |
| Claim: | 1. Injection molding apparatus comprising |
| Claim: | a) a tubular barrel having an inner surface, the barrel including a material inlet and a material outlet spaced axially from the material inlet; |
| Claim: | b) a plasticating screw rotatably and slidably supported in the barrel for plasticating polymeric material and for conveying polymeric material within the barrel from the material inlet to the material outlet, the screw including a forward end facing toward the material outlet; |
| Claim: | c) flow control means carried by the plasticating screw at a forward end of the screw for controlling flow of plasticated polymeric material from the screw toward the material outlet, the flow control means including body means extending outwardly from the forward end of the screw said body means being rotationally and translationally movable relative to the screw while the screw is rotating to plasticate polymeric material, the body means having a forward end and a back end, retainer means carried by the forward end of the screw and surrounding the body means for retaining the body means, the retainer means including stop means for limiting forward axial translational movement of the body means relative to the screw and including valve seat means facing in a forward direction relative to the screw for defining a first valve surface, sealing means positioned between the body means and the retainer means to prevent flow of plasticated material therebetween, the sealing means including an annular metallic sealing ring, and a screw tip carried by the forward end of the body means, the screw tip having a longitudinal axis and including a second valve surface facing and engagable with the first valve surface for selectively opening and closing a plasticated material flow path between the screw and the screw tip, the screw tip having an outer diameter sufficient to prevent flow of plasticated material between the screw tip and the tubular barrel, and the screw tip including passageway means for permitting flow of plasticated material from the screw through the flow control means to an area forward of the screw when the second valve surface is spaced from the first valve surface. |
| Claim: | 2. Injection molding apparatus in accordance with claim 1, wherein the screw tip passageway means includes a plurality of longitudinally extending flow paths through the screw tip to define a plurality of openings facing the screw, the openings each positioned radially inwardly of the second valve surface. |
| Claim: | 3. Injection molding apparatus in accordance with claim 2, wherein the flow paths in the screw tip are substantially equidistantly spaced about the longitudinal axis of the screw tip. |
| Claim: | 4. Injection molding apparatus in accordance with claim 3, wherein the flow paths are arc-shaped in transverse cross section. |
| Claim: | 5. Injection molding apparatus in accordance with claim 1, wherein the valve seat means includes an annular sealing surface. |
| Claim: | 6. Injection molding apparatus in accordance with claim 5, wherein the screw has a longitudinal axis and the annular sealing surface is inclined relative to the screw axis. |
| Claim: | 7. Injection molding apparatus in accordance with claim 1, wherein the sealing ring has a substantially rectangular cross section. |
| Claim: | 8. Injection molding apparatus in accordance with claim 1, wherein the sealing ring is carried in an annular recess on the body means. |
| Claim: | 9. Injection molding apparatus comprising |
| Claim: | c) anti-backflow valve means carried at the forward end of the screw for permitting flow of plasticated material only in a direction toward and past the forward end of the screw and for preventing backflow of plasticated material into the screw from the forward end thereof, the valve means including a valve seat carried by the screw for rotation therewith, the valve seat including a first sealing surface, and closure means slidably engaging the barrel inner surface and movable toward and away from the valve seat for selectively preventing and permitting flow through the valve means, the closure means including rod means extending form the closure means toward the forward end of the screw for rotational movement and axial translational movement of the rod means relative to an axial bore in the valve seat, sealing means positioned between the axial bore in the valve seat and the rod means for preventing the flow of plasticated material into the axial bore, the sealing means including an annular metallic sealing ring, the closure means including a second sealing surface engagable with the first sealing surface for sealing engagement therewith to prevent flow of plasticated material past the valve means, the closure means including passageway means positioned downstream of the second sealing surface to permit flow of plasticated material through the closure means when the second sealing surface is spaced from the first sealing surface, to selectively permit flow of plasticated material through the valve means. |
| Claim: | 10. Injection molding apparatus in accordance with claim 9, wherein the closure means includes a body member that is rotatably and axially translatably received in a bore at the forward end of the screw, and the screw includes retaining means for rotatably and axially translatably retaining the body member relative to the screw. |
| Claim: | 11. Injection molding apparatus in accordance with claim 10, wherein the body member includes an enlarged end rotatably and axially translatably received within the forward end of the screw. |
| Claim: | 12. Injection molding apparatus in accordance with claim 9, wherein the valve seat means is frustoconical. |
| Claim: | 13. Injection molding apparatus in accordance with claim 9, the valve surface means is frustoconical. |
| Claim: | 14. Injection molding apparatus in accordance with claim 10, wherein the body member includes an enlarged end portion for engagement with the retainer means carried by the screw for limiting forward movement of the body member relative to the screw, the end portion having a smaller axial length than the axial length of the bore with the retaining means in position, to permit limited axial movement of the body member relative to the screw. |
| Claim: | 15. Injection molding apparatus in accordance with claim 9, wherein the sealing means has a substantially rectangular cross section. |
| Claim: | 16. Injection molding apparatus in accordance with claim 9, wherein the sealing ring is carried in an annular recess in the rod means. |
| Claim: | 17. An anti-backflow valve for the forward end of a plasticating screw, the screw adapted to be rotatably and axially slidably carried in a barrel, said valve comprising |
| Claim: | a) body means adapted to extend outwardly from the forward end of the screw and rotatable and axially translatably relative to the screw while the screw is rotating to plasticate polymeric material, the body means including a forward end and a back end; |
| Claim: | b) retainer means adapted to be secured to the forward end of the screw and surrounding a portion of the body means, the retainer means defining a forward stop for limiting forward axial translation of the body means relative to the screw, and valve seat means for defining a first sealing surface carried by the retainer means and facing in a forward direction relative to the screw; |
| Claim: | c) sealing means positioned between the body means and the retainer means to prevent flow of plasticated material therebetween, the sealing means including an annular metallic sealing ring having a substantially rectangular cross section; and |
| Claim: | d) screw tip means carried by the forward end of the body means, the screw tip means including valve surface means for defining a second sealing surface facing and engagable with the first sealing surface of the valve seat means for selectively opening and closing a plasticated material flow path between the screw and a space forward of the screw, the screw tip means having an outer diameter sufficient to prevent flow of plasticated material between the screw tip means and the tubular barrel and including passageway means extending longitudinally through the screw tip means and defining an opening facing the screw, the opening positioned radially inwardly of the valve surface means for permitting flow of plasticated material from the screw through the valve to the space forward of the screw when the valve surface means is spaced from the valve seat means. |
| Current U.S. Class: | 425/562; 26432/812; 425/563 |
| Current International Class: | B29C 4552 |
| Patent References Cited: | 3007202 November 1961 Wucher 3319299 May 1967 Kiraly 3550208 December 1970 Peters 3888393 June 1975 Drori 4349044 September 1982 Schirmer 4377180 March 1983 Biljes 4477242 October 1984 Eichlseder et al. 4498860 February 1985 Gahan 4512733 April 1985 Eichlseder et al. 4582224 April 1986 Proksa et al. 4643665 February 1987 Zeiger 4850851 July 1989 Dinerman 4954073 September 1990 Oriez et al. |
| Primary Examiner: | Heitbrink, Timothy |
| Attorney, Agent or Firm: | Nies, Kurz, Bergert & Tamburro |
| Accession Number: | edspgr.05044926 |
| Database: | USPTO Patent Grants |
| Language: | English |
|---|