US4377541A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing low voltage varistors
Assignee: General Electric Co
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Filing: 1978-08-21
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Granted: 1983-03-22
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Expires: 1998-08-21
Abstract
Abstract Low voltage varistors having one or more recesses or dimples which reduces the thickness of the varistor in the recessed areas are provided by an improved process which comprises fitting a pressing surface on a die punch with a resilient material, preferably an abhesive material such as polydimethylsiloxane, having one or more nipples whereby during pressing of a metal oxide varistor powder contained in the die cavity the nipple imparts a depression thereby reducing the thickness of the varistor body in said depression. In addition, the resilient material aids in the distribution of the powder during pressing and with the preferred abhesive material aids also in the release of the pressed body from the die.
Inventors
- 👤 Carl F. Bobik
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:33
CPC Classifications
B; B30; B30B; B30B15/00; B30B15/02; B30B15/022; B30B15/024; B22; B22F; B22F5/00; B22F5/10; H; H01; H01C; H01C17/00; H01C17/30; H01C7/00; H01C7/10; H01C7/102
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
98 words
In a method of forming a varistor comprising compressing a suitable powder in a die to a compact body having at least one recess, and sintering said body, the improvement comprising fitting a pressing surface in the die containing the powder with a resilient material having as part thereof at least one resilient protrusion, which during pressing imparts a depression into the surface of said powder to produce a region of reduced thickness in said compact body opposite said protrusion, said protrusion deforming during said pressing operation and returning to its undeformed shape as the compression is released.
Claim 2
Dependent Claim
98 words
In a method of forming a varistor comprising compressing a suitable powder in a die to a compact body having at least one recess, and sintering said body, the improvement comprising fitting a pressing surface in the die containing the powder with a resilient material having as part thereof at least one resilient protrusion, which during pressing imparts a depression into the surface of said powder to produce a region of reduced thickness in said compact body opposite said protrusion, said protrusion deforming during said pressing operation and returning to its undeformed shape as the compression is released.
Claim 3
Dependent Claim
20 words
The method of claim 1 in which the resilient material has a plurality of protrusions in the shape of nipples.
Claim 4
Dependent Claim
15 words
The method of claim 2 wherein the nipples are arranged substantially in a honeycomb pattern.
Claim 5
Dependent Claim
25 words
The method of claim 1 in which all of the pressing surfaces of the die are fitted with resilient material having a plurality of nipples.
Claim 6
Dependent Claim
15 words
The method of claim 4 wherein the nipples are arranged substantially in a honeycomb pattern.
Claim 7
Dependent Claim
12 words
The method of claim 1 in which the resilient material is abhesive.
Claim 8
Independent Claim
22 words
The method of claims 1 in which the resilient material has a Shore A hardness of between about 40 and about 60.
Claim 9
Independent Claim
13 words
The method of claims 1 in which the resilient material is a polydimethylsiloxane.
Claim 10
Independent Claim
14 words
The method of claims 1 in which the resilient material is cured RTV resin.
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) | 1986-03-21 | 1986-09-20 | 1987-03-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-03-21 | 1990-09-20 | 1991-03-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-03-21 | 1994-09-20 | 1995-03-22 | $7700.00 | Window Closed / Lapsed |