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US3596485A
Expired / Lapsed
US
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Hydromechanical method and device for the reverse redrawing of sheet metal
Assignee: SEG Hausgeraete GmbH
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Filing: 1969-09-11
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Granted: 1971-08-03
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Expires: 1989-09-11
Abstract
Abstract Blanks for sheet metal are drawn with the aid of a pressure container, a liquid displacing annular plunger pressure tightly glidable in the container and having a top adapted for accommodating the blank, a holddown for pressing the blank against the top, and a draw punch passing through the holddown. The container and plunger are first filled with liquid up to the top. Then the blank is placed onto the top, whereafter the holddown is forced downwardly against the blank, thereby pressing the plunger into the container. The increasing liquid pressure in the container draws the blank to a shape bulging upwardly into the holddown. Thereafter, the blank is reversely redrawn into the pressure container by pressing the punch from above against the blank and downwardly into the container.
Inventors
- 👤 Eugen Burk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 04:56
CPC Classifications
B; B21; B21D; B21D22/00; B21D22/20; B21D22/205
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
136 words
A hydromechanical reverse redrawing method for shaping blanks of sheet metal with the aid of a pressure container, a liquid displacing annular plunger pressure tightly glidable in said container and having outside said container a top adapted for accommodating a blank, a holddown for pressing the blank against the top and a draw punch passing through the holddown, which method comprises the steps of filling the container and plunger with liquid up to the top, placing the blank onto the top, forcing the holddown against the blank and thereby pressing the plunger into the container whereby the increasing liquid pressure draws the blank to a preshape bulging upwardly into the holddown, and thereafter reversely redrawing the blank into the pressure container by pressing the punch from above against the preshaped blank and downwardly into the container.
Claim 2
Dependent Claim
136 words
A hydromechanical reverse redrawing method for shaping blanks of sheet metal with the aid of a pressure container, a liquid displacing annular plunger pressure tightly glidable in said container and having outside said container a top adapted for accommodating a blank, a holddown for pressing the blank against the top and a draw punch passing through the holddown, which method comprises the steps of filling the container and plunger with liquid up to the top, placing the blank onto the top, forcing the holddown against the blank and thereby pressing the plunger into the container whereby the increasing liquid pressure draws the blank to a preshape bulging upwardly into the holddown, and thereafter reversely redrawing the blank into the pressure container by pressing the punch from above against the preshaped blank and downwardly into the container.
Claim 3
Dependent Claim
44 words
The method according to claim 1, which comprises maintaining the pressure in the pressure container during reverse redrawing substantially constant and simultaneously discharging from the container a quantity of liquid corresponding to the reduction in liquid volume displaced by the workpiece being reversely redrawn.
Claim 4
Dependent Claim
139 words
A hydromechanical reverse redrawing device for shaping blanks of sheet metal, comprising an upwardly open container for pressure liquid having liquid supply ducts, a plunger having a hollow and being glidably and pressure tightly displaceable in said container, said plunger having a flange with a top outside and above said container and having sealable means on said top for receiving the workpiece blank across the hollow so that the blank when pressed against the plunger forms a closure of said container, an holddown movable under pressure toward the container to force the plunger into the container whereby the increasing liquid pressure draws the workpiece blank to a shape bulging upwardly into the holddown, and a draw punch vertically movable in the hollow of said holddown for reversely redrawing the preshaped workpiece by pressing it from above into the container.
Claim 5
Dependent Claim
139 words
A hydromechanical reverse redrawing device for shaping blanks of sheet metal, comprising an upwardly open container for pressure liquid having liquid supply ducts, a plunger having a hollow and being glidably and pressure tightly displaceable in said container, said plunger having a flange with a top outside and above said container and having sealable means on said top for receiving the workpiece blank across the hollow so that the blank when pressed against the plunger forms a closure of said container, an holddown movable under pressure toward the container to force the plunger into the container whereby the increasing liquid pressure draws the workpiece blank to a shape bulging upwardly into the holddown, and a draw punch vertically movable in the hollow of said holddown for reversely redrawing the preshaped workpiece by pressing it from above into the container.
Claim 6
Dependent Claim
31 words
In a device according to claim 3, said punch, when in its top position, forming within the hollow of said holddown an abutment for limiting the upward draw of the blank.
Claim 7
Dependent Claim
23 words
In a device according to claim 3, said holddown having an inner width at least 30 percent larger than that of said punch.
Claim 8
Dependent Claim
19 words
A device according to claim 3, comprising stroke limiting stop means between said pressure container and said displacing plunger.
Claim 9
Dependent Claim
35 words
A device according to claim 3, comprising a liquid-collector tank and a pressure control valve through which said pressure container communicates with said tank for maintaining in said container a valve-controlled pressure during reverse redrawing.
References Cited (Backward Citations)
US3208255A
Cited
US3504070A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-02 | 1975-02-01 | 1975-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-02 | 1979-02-01 | 1979-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-02 | 1983-02-01 | 1983-08-03 | $7700.00 | Window Closed / Lapsed |