US3880978A
Expired / Lapsed
US
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Method for forming a remote annular rim of plastic material
Assignee: Ford Motor Co
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Filing: 1974-04-23
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Granted: 1975-04-29
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Expires: 1994-04-23
Abstract
Abstract A method is disclosed for forming a remote mounting web and rim of plastic material to provide that rim with good structural stength and reliable integrity. The method is intended for use with injection molding plastic forming equipment and is compatible with transfer molding techniques. The remote rim is formed of plastic material which is required to flow under heat and pressure from a central location through web portions to form an annular exterior rim portion which must be continuous and free from defects. In order to assure that the rim portion has the desired integrity and freedom from defects, the mold is provided with means defining high resistance flow paths and low resistance flow paths such that a staggered and overlapping flow pattern is provided for the plastic material. This prevents knit lines from forming across the rim which would constitute a defect or in an extreme case would provide a discontinuity in the annular rim portion. The high resistance flow paths comprise sharp angular changes in flow direction coupled with a relatively thin cross sectional flow area while the low resistance flow paths comprise a gradual angular change in flow direction provided by a relatively large radius of curvature combined with a relatively thicker cross sectional flow area. At the annular rim portion, a relatively short high resistance flow path is arranged in radial proximity to a relatively long low resistance flow path and to be circumferentially adjacent to a second relatively long low resistance flow path.
Inventors
- 👤 Theodore G Apostoleris
- 👤 Marion L Callahan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:43
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/0025; B29C45/0046; B29C45/17; B29C45/26; B29C45/34
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
130 words
The method of forming, in a mold, a flow molded plastic structure having a central body portion and a remote annular rim connected to a central body portion by at least one generally radially directed spoke member comprising the steps of: introducing plastic material into the mold at a central location; flowing the plastic material, under heat and pressure, through the central body portion and at least one spoke member; causing the plastic material to flow from the at least one spoke member into the annular rim through a first pair of radially offset, circumferentially oppositely directed low impedance flow paths and a second pair of radially offset, circumferentially oppositely directed high impedance flow paths, each path of said first pair being radially adjacent a path of said second pair.
Claim 2
Independent Claim
130 words
The method of forming, in a mold, a flow molded plastic structure having a central body portion and a remote annular rim connected to a central body portion by at least one generally radially directed spoke member comprising the steps of: introducing plastic material into the mold at a central location; flowing the plastic material, under heat and pressure, through the central body portion and at least one spoke member; causing the plastic material to flow from the at least one spoke member into the annular rim through a first pair of radially offset, circumferentially oppositely directed low impedance flow paths and a second pair of radially offset, circumferentially oppositely directed high impedance flow paths, each path of said first pair being radially adjacent a path of said second pair.
Claim 3
Dependent Claim
78 words
The method of claim 1 wherein the annular rim is connected to the central body portion by a plurality of spoke members and the step of causing the plastic material to flow into the rim includes the step of: causing the plastic material to flow into the annular rim through each of the plurality of spoke members and each spoke member communicates with first and second pairs of annular rim flow paths of respectively low and high impedance.
Claim 4
Dependent Claim
48 words
The method of claim 2 wherein the first and second pairs of annular rim rlow paths which communicate with a spoke member are arranged to communicate at their opposite ends with second and first pairs of annular rim flow paths, respectively, which communicate with the adjacent spoke members.
Claim 5
Dependent Claim
45 words
The method of claim 1 wherein the step of causing the plastic material to flow is accomplished by providing the first pair of flow paths with a relatively large flow cross-section while providing the second pair of flow paths with a relatively small flow cross-section.
Claim 6
Dependent Claim
38 words
The method of claim 1 wherein the first pair of Flow paths are also provided with relatively gradual changes in flow direction while the second pair of flow paths are provided with relatively abrupt changes in flow direction.
Claim 7
Dependent Claim
188 words
In a method for flow molding a unitary plastic structure having a remote annular rim connected to a central portion by at least one generally radially directed spoke member wherein a mold is formed having the general configuration of the plastic structure and plastic material is introduced into the mold at a central location and caused to flow, under heat and pressure, to fill the mold, the improvement comprising the steps of: defining inner rim segments of the annular rim and outer rim segments of the annular rim, the inner and outer rim segments being fillable by plastic material flow from the at least one spoke member in clockwise and counterclockwise directions; and causing the plastic material to flow into an inner rim segment in one of said clockwise and counterclockwise directions and to flow into an outer rim segment in the other of said clockwise and counterclockwise directions with a relative high lineal speed; and causing the plastic material to flow into a second inner rim segment in the other direction and into an outer rim segment in the one direction at a relatively low lineal speed.
Claim 8
Dependent Claim
188 words
In a method for flow molding a unitary plastic structure having a remote annular rim connected to a central portion by at least one generally radially directed spoke member wherein a mold is formed having the general configuration of the plastic structure and plastic material is introduced into the mold at a central location and caused to flow, under heat and pressure, to fill the mold, the improvement comprising the steps of: defining inner rim segments of the annular rim and outer rim segments of the annular rim, the inner and outer rim segments being fillable by plastic material flow from the at least one spoke member in clockwise and counterclockwise directions; and causing the plastic material to flow into an inner rim segment in one of said clockwise and counterclockwise directions and to flow into an outer rim segment in the other of said clockwise and counterclockwise directions with a relative high lineal speed; and causing the plastic material to flow into a second inner rim segment in the other direction and into an outer rim segment in the one direction at a relatively low lineal speed.
Claim 9
Dependent Claim
124 words
The improved method of claim 6 wherein the steps of causing the plastic material to flow into the inner and outer rim segments at different lineal speeds comprise the steps of: providing a first relatively high impedance flow path in an inner rim segment in the other direction from the at least one spoke; providing a second relatively high impedance flow path in an outer rim segment in the one direction from the at least one spoke; providing a first relatively low impedance flow path in an inner rim segment in the one direction from the at least one spoke; and providing a second relatively low impedance flow path in an outer rim segment in the other direction from the at least one spoke.
Claim 10
Dependent Claim
35 words
The improved method of claim 7 wherein the steps of providing relatively low impedance flow paths comprise the steps of: providing relatively large flow path cross sectional areas; and providing relatively gradual flow direction changes.
Claim 11
Dependent Claim
35 words
The improved method of claim 7 wherein the steps of providing relatively high impedance flow paths comprise the steps of: providing relatively small flow path cross sectional areas; and providing relatively abrupt flow direction changes.
Claim 12
Dependent Claim
37 words
The improved method of claim 6 wherein the unitary plastic structure includes a plurality of spoke members and the steps of causing the plastic material to flow into the rim segments is performed for each spoke member.
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) | 1978-04-28 | 1978-10-28 | 1979-04-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-28 | 1982-10-28 | 1983-04-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-28 | 1986-10-28 | 1987-04-29 | $7700.00 | Window Closed / Lapsed |