US3602950A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Injection molding machine
Assignee: Eckert and Ziegler GmbH
•
Filing: 1969-01-15
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Granted: 1971-09-07
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Expires: 1989-01-15
Abstract
Abstract An injection molding machine for thermosetting plastic material which comprises a heatable cylinder having a constant internal diameter, and a rotary and axially movable screw which transports plastic material toward the outlet of the cylinder. The diameter of the screw thread decreases gradually toward the tip of the screw along an intermediate portion whose axial length is between one and eight times the maximum diameter of the screw. The diameter of the core in the intermediate portion of the screw also decreases gradually but the pitch of threads on such intermediate portion increases toward the tip. This reduces wear on the internal surface of the cylinder and on the external surface of the screw.
Inventors
- 👤 Friedrich Bernd Bielfeldt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:44
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/17; B29C45/46; B29C45/47; B29C45/50; B29C45/58; B29C45/60
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
16 words
A combination as defined in claim 1, wherein said front end portion is a conical tip.
Claim 2
Dependent Claim
17 words
A combination as defined in claim 2, wherein said helical thread ends short of said conical tip.
Claim 3
Dependent Claim
24 words
A combination as defined in claim 2, wherein the angle of taper of said intermediate portion is less than that of said conical tip.
Claim 4
Dependent Claim
27 words
A combination as defined in claim 1, wherein the axial length of said intermediate portion is between one and eight times the maximum diameter of said screw.
Claim 5
Dependent Claim
21 words
A combination as defined in claim 5, wherein said intermediate portion tapers gradually toward the front end portion of said screw.
Claim 6
Dependent Claim
27 words
A combination as defined in claim 1, wherein the axial length of said intermediate portion is between three and five times the maximum diameter of said screw.
Claim 7
Dependent Claim
38 words
A combination as defined in claim 1, wherein said external helical thread has a ridge and wherein at least the ridge of the thread on said intermediate portion of the screw is bounded by a strongly rounded surface.
Claim 8
Dependent Claim
27 words
A combination as defined in claim 8, wherein the radius of curvature of said rounded surface is at least one-fortieth of the maximum diameter of the screw.
Claim 9
Dependent Claim
40 words
A combination as defined in claim 1, wherein said screw includes a core and an external helical thread provided on said core, said core tapering toward said front end portion over the length of said intermediate portion of the screw.
Claim 10
Dependent Claim
27 words
A combination as defined in claim 1, wherein the pitch of the thread on said intermediate portion increases gradually in a direction toward said front end portion.
Claim 11
Dependent Claim
42 words
A combination as defined in claim 1, wherein said screw comprises a core and an external helical thread on said core, and wherein the pitch of the thread on said intermediate portion increases gradually toward said front end portion of the screw.
References Cited (Backward Citations)
US2496625A
Cited
US3065502A
Cited
US2743812A
Cited
US3164375A
Cited
US3121914A
Cited
US3169275A
Cited
US3499187A
Cited
US3427639A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-06 | 1975-03-08 | 1975-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-06 | 1979-03-08 | 1979-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-06 | 1983-03-08 | 1983-09-07 | $7700.00 | Window Closed / Lapsed |