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US3580122A
Expired / Lapsed
US
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Apparatus for making knockouts in electrical boxes formed of plastic material
Assignee: All Steel Equipment Inc
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Filing: 1968-12-13
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Granted: 1971-05-25
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Expires: 1988-12-13
Abstract
Abstract Knockouts are formed in electrical fixtures, such as connector boxes made of plastic sheet material, by punching the knockouts from plastic sheet or blanks prior to shaping into the fixture or by shaping the fixture and then punching out the knockouts. By resiliently supporting the material surrounding the knockout area on the punch side and resiliently biasing a knockout stripper against the surface of the knockout opposite that contacted by the punch, knockouts can be punched out and replaced in the material in a single operation if the opposite biasing forces of the support and knockout stripper are properly correlated.
Inventors
- 👤 James C Powell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 14:51
CPC Classifications
H; H02; H02G; H02G3/00; H02G3/02; H02G3/08; H02G3/081; H02G3/083; B; B21; B21D; B21D28/00; B21D28/02; B21D28/14; B21D28/145; B26; B26F; B26F1/00; B26F1/02; Y; Y10; Y10T; Y10T83/00; Y10T83/202; Y10T83/209; Y10T83/2092; Y10T83/2096; Y10T83/2122; Y10T83/2133; Y10T83/384; Y10T83/387; Y10T83/388; Y10T83/395; Y10T83/40; Y10T83/401; Y10T83/402; Y10T83/929; Y10T83/9411; Y10T83/9423; Y10T83/9425; Y10T83/9449
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
214 words
A device for forming knockouts in plastic sheet material comprising: a. a spring-supported plate; b. a rigidly mounted punch element extending through said plate so that the end of said element is in approximately the same plane as said plate when the latter is in its normal position; c. a die element in alignment with said punch element and adapted to be reciprocated toward and away from said punch element; d. a knockout stripper snugly and slidably mounted in the cavity of said die; e. spring means biasing said knockout stripper toward said punch element; f. spring means biasing said plate toward said knockout stripper; g. said die element and said knockout stripper having cooperating means to prevent said knockout stripper from projecting beyond the face of said die element and to move said knockout stripper in the direction of the die during its release stroke; h. said spring means being sufficiently strong to return the knockout to a position in the plastic sheet material substantially coplanar therewith at the same locus from which the knockout is cut; and i. said punch and die elements being formed with aligned grooves of different sizes to form a tab connecting the knockout to the plastic sheet material that is located outside the periphery of the knockout.
Claim 2
Independent Claim
214 words
A device for forming knockouts in plastic sheet material comprising: a. a spring-supported plate; b. a rigidly mounted punch element extending through said plate so that the end of said element is in approximately the same plane as said plate when the latter is in its normal position; c. a die element in alignment with said punch element and adapted to be reciprocated toward and away from said punch element; d. a knockout stripper snugly and slidably mounted in the cavity of said die; e. spring means biasing said knockout stripper toward said punch element; f. spring means biasing said plate toward said knockout stripper; g. said die element and said knockout stripper having cooperating means to prevent said knockout stripper from projecting beyond the face of said die element and to move said knockout stripper in the direction of the die during its release stroke; h. said spring means being sufficiently strong to return the knockout to a position in the plastic sheet material substantially coplanar therewith at the same locus from which the knockout is cut; and i. said punch and die elements being formed with aligned grooves of different sizes to form a tab connecting the knockout to the plastic sheet material that is located outside the periphery of the knockout.
Claim 3
Dependent Claim
37 words
A device in accordance with claim 1 in which the punch element extends upwardly through said plate from a rigidly mounted punch holder and the plate is supported in a horizontal position by springs resistant to compression.
Claim 4
Dependent Claim
42 words
A device in accordance with claim 1 in which said knockout stripper cooperating means is a shoulder formed adjacent one end of said stripper and said die element cooperating means is a plate, extending into the die cavity, which engages said shoulder.
Claim 5
Dependent Claim
45 words
A device in accordance with claim 1 in which said spring supported plate is located above a solid base so that in its normal position the space between said base and said plate is at least as great as the thickness of the sheet material.
Claim 6
Dependent Claim
21 words
A device in accordance with claim 1 in which said knockout strippers are movable toward and away from the sheet material.
Claim 7
Dependent Claim
37 words
A device in accordance with claim 1 in which said cooperating means are arranged to move said knockout stripper free of the knockout when said die member is moved free of the sheet on its release stroke.
Claim 8
Dependent Claim
42 words
A device in accordance with claim 1 in which said knockout stripper cooperating means is a shoulder formed adjacent one end of said stripper and said die element cooperating means is a plate, extending into the die cavity, which engages said shoulder.
Claim 9
Dependent Claim
45 words
A device in accordance with claim 1 in which said spring supported plate is located above a solid base so that in its normal position the space between said base and said plate is at least as great as the thickness of the sheet material.
Claim 10
Dependent Claim
21 words
A device in accordance with claim 1 in which said knockout strippers are movable toward and away from the sheet material.
Claim 11
Dependent Claim
37 words
A device in accordance with claim 1 in which said cooperating means are arranged to move said knockout stripper free of the knockout when said die member is moved free of the sheet on its release stroke.
Claim 12
Independent Claim
155 words
A device for forming a knockout in plastic material having substantially parallel opposite surfaces comprising: a. a stationary die; b. a movable knockout punch aligned with said die; c. means for reciprocating said punch to and from operational and release positions; d. a resiliently biased knockout stripper mounted in said die and biased toward said punch; e. a support surrounding said punch and resiliently biased toward said die; f. means for resiliently biasing said knockout stripper and said support toward each other during the release stroke of said punch with sufficient force to return said knockout to the space in said material from which it was punched during the punching stroke of said punch, in substantially coplanar relationship with said material; and g. said punch and die being formed with aligned grooves of different sizes to form a tab connecting the knockout to the plastic material that is located outside the periphery of the knockout.
Claim 13
Independent Claim
155 words
A device for forming a knockout in plastic material having substantially parallel opposite surfaces comprising: a. a stationary die; b. a movable knockout punch aligned with said die; c. means for reciprocating said punch to and from operational and release positions; d. a resiliently biased knockout stripper mounted in said die and biased toward said punch; e. a support surrounding said punch and resiliently biased toward said die; f. means for resiliently biasing said knockout stripper and said support toward each other during the release stroke of said punch with sufficient force to return said knockout to the space in said material from which it was punched during the punching stroke of said punch, in substantially coplanar relationship with said material; and g. said punch and die being formed with aligned grooves of different sizes to form a tab connecting the knockout to the plastic material that is located outside the periphery of the knockout.
Claim 14
Dependent Claim
33 words
A device in accordance with claim 11 in which: h. said punch is actuated during its punch stroke by means of a cam mechanism and is released by means of a spring mechanism.
Claim 15
Dependent Claim
24 words
A device in accordance with claim 11 in which: h. said knockout punch is biased by means of a combination cam and resilient mechanism.
Claim 16
Dependent Claim
51 words
A device in accordance with claim 12 in which: i. said die contains knockout strippers operated in opposite directions on opposite sides of said die by a common cam and resilient biasing means; and j. separate punches, aligned with the opposite sides of said die, are actuated by a common actuator.
Claim 17
Dependent Claim
24 words
A device in accordance with claim 11 in which: h. said knockout punch is biased by means of a combination cam and resilient mechanism.
Claim 18
Dependent Claim
51 words
A device in accordance with claim 11 in which: i. said die contains knockout strippers operated in opposite directions on opposite sides of said die by a common cam and resilient biasing means; and j. separate punches, aligned with the opposite sides of said die, are actuated by a common actuator.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-05-24 | 1974-11-23 | 1975-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-24 | 1978-11-23 | 1979-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-24 | 1982-11-23 | 1983-05-25 | $7700.00 | Window Closed / Lapsed |