Patent US3929953A successfully refreshed from Google Patents.
US3929953A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for forming noncircular thermoplastic cupped articles
Assignee: Shell USA Inc
•
Filing: 1974-09-12
•
Granted: 1975-12-30
•
Expires: 1994-09-12
Abstract
Abstract An improved method for forming noncircular cupped articles from thermoplastic sheet by plug-assist drawing of the sheet in solid phase utilizing a plug or mandrel with recessed sides in at least about the upper half of the mandrel. Plug-assist drawing of noncircular containers, such as square or rectangular containers having rounded edges, from thermoplastic sheet in the solid phase, utilizing such a plug with recessed sides results in articles having greatly improved uniformity of wall thickness in the edges and sidewalls, when compared with drawing by means of a plug in which the sides are not recessed.
Inventors
- 👤 Der Gaag Gerrit Van
- 👤 Thomas C Tomey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 10:33
CPC Classifications
B; B29; B29C; B29C51/00; B29C51/04; B29C51/10
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
215 words
A METHOD FOR MOLDING HOLLOW ARTICLES OF A CONFIGURATION HAVING AN APPROXIMATELY POLYGONAL CROSS-SECTION WITH ROUNDED CORNERS, FROM THERMOPLASTIC MATERIAL OVER THE OPENING OF ING A SHEET OF THERMOPLASTIC MATERIAL OVER THE OPENING OF A MOLDING CAVITY HAVING SAID CONFIGURATION, DRAWING THE THERMOPLASTIC SHEET INTO THE CAVITY WHILE THE SHEET IS MAINTAINED IN THE SOLID PHASE AT A TEMPERATURE BELOW ITS MELTING POINT BY LOWERING A PLUG HAVING A MODIFIED POLYGONAL SHAPE, THE MODIFICATION IN CROSS-SECTION CONSISTING OF AN UPPER PORTION WITH ROUNDED CORNERS AND CONCAVE INDENTATION OF THE SIDE WALLS AND A LOWER PORTION CONVERGING FROM SAID INDENTED UPPER PORTION TO AN UNINDENTED CONFIGURATION APPROXIMATELY ELLEPTICAL IN PLANES PARALLEL TO THE PLANE MADE BY THE UNDRAWN SHEET AND APPROXIMATELY PARABOLIC IN PHASE PERPENDICULAR TO THE UNDRAWN SHEET, ON TO THE SHEET AND INTO THE MOLDING CAVITY, THEREBY CAUSING THE SHEET TO BE FORCED INTO CAVITY BY FIRST CONTACTING THE LOWER PART OF THE PLUG IN A SEQUENCE OF PROGRESSIVELY LARGER ELIPTICAL LINES OF CONTACT, THEN THE LOWER PART OF THE PLUG AND ONLY THE ROUNDED CORNERS OF THE UPPER PART OF THE PLUUG AND THEREAFTER PROVIDING A FLUID PRESSURE DIFFERENCE BETWEEN SAID PLUG AND FULY PLUG STRETCHED SHEET FORCING THE SHEET UP AGAINST THE WALLS OF THE MOLD CAVITY TO FORM THE HOLLOW ARTICLE.
Claim 2
Independent Claim
215 words
A METHOD FOR MOLDING HOLLOW ARTICLES OF A CONFIGURATION HAVING AN APPROXIMATELY POLYGONAL CROSS-SECTION WITH ROUNDED CORNERS, FROM THERMOPLASTIC MATERIAL OVER THE OPENING OF ING A SHEET OF THERMOPLASTIC MATERIAL OVER THE OPENING OF A MOLDING CAVITY HAVING SAID CONFIGURATION, DRAWING THE THERMOPLASTIC SHEET INTO THE CAVITY WHILE THE SHEET IS MAINTAINED IN THE SOLID PHASE AT A TEMPERATURE BELOW ITS MELTING POINT BY LOWERING A PLUG HAVING A MODIFIED POLYGONAL SHAPE, THE MODIFICATION IN CROSS-SECTION CONSISTING OF AN UPPER PORTION WITH ROUNDED CORNERS AND CONCAVE INDENTATION OF THE SIDE WALLS AND A LOWER PORTION CONVERGING FROM SAID INDENTED UPPER PORTION TO AN UNINDENTED CONFIGURATION APPROXIMATELY ELLEPTICAL IN PLANES PARALLEL TO THE PLANE MADE BY THE UNDRAWN SHEET AND APPROXIMATELY PARABOLIC IN PHASE PERPENDICULAR TO THE UNDRAWN SHEET, ON TO THE SHEET AND INTO THE MOLDING CAVITY, THEREBY CAUSING THE SHEET TO BE FORCED INTO CAVITY BY FIRST CONTACTING THE LOWER PART OF THE PLUG IN A SEQUENCE OF PROGRESSIVELY LARGER ELIPTICAL LINES OF CONTACT, THEN THE LOWER PART OF THE PLUG AND ONLY THE ROUNDED CORNERS OF THE UPPER PART OF THE PLUUG AND THEREAFTER PROVIDING A FLUID PRESSURE DIFFERENCE BETWEEN SAID PLUG AND FULY PLUG STRETCHED SHEET FORCING THE SHEET UP AGAINST THE WALLS OF THE MOLD CAVITY TO FORM THE HOLLOW ARTICLE.
Claim 3
Dependent Claim
14 words
Method according to claim 1 in which said approximately polygonal cross-section is approximately rectangular.
Claim 4
Dependent Claim
14 words
Method according to claim 1 in which said approximately polygonal cross-section is approximately square.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-29 | 1979-06-30 | 1979-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-29 | 1983-06-30 | 1983-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-29 | 1987-06-30 | 1987-12-30 | $7700.00 | Window Closed / Lapsed |