Presses – Methods
Utility Patent
1999-03-02
2001-01-02
Gerrity, Stephen F. (Department: 3721)
Presses
Methods
C100S267000, C264S320000, C425S078000, C425S355000, C425S398000, C425S411000
Utility Patent
active
06167802
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to presses of the type generally employed for compressing, volume reducing, crimping, pressure inserting, and other pressure-based processes by exerting pressure to at least two opposite sides of the material being worked on. The invention is characterized by a sliding frame part that is movably displaceable within a fixed frame base and an oppositely disposed pressure generator, by means of the force supplied by a single pressure generating (force exerting) actuator.
PRIOR ART
Presses used in general industrial applications are often the single action type which employ a single pressure generating actuator as a means of applying pressure in one direction. This design has an inherent shortcoming in that it cannot simultaneously apply uniform pressure to both the upper and lower surfaces of the workpiece. Dualaction presses have been developed as a means of eliminating this shortcoming through a mechanism that is able to apply pressure simultaneously to opposing sides of the workpiece. This type of press presently requires the use of two pressure generating actuators installed on the press frame as a means of simultaneously pressurizing opposing surfaces of the workpiece. Load cells are further employed as a means of measuring and comparing the operating pressure of each of the aforesaid actuators in order to provide uniform pressure application there between. As these actuators require a feedback type of control system, the resulting press design is relatively complex and operation is difficult.
In cases where the aforesaid dual-action press is employed as a powdered metal molding press, operation requires that the die and lower punch assembly be temporarily raised through the insertion of a spacer between the punch and frame, powdered metal is then inserted into the die, and the die contents subjected to pre-forming pressure through a load applied by the lower punch. This pre-forming pressure is then released, the spacer removed, and full molding pressure applied by both actuators as means of forming the finished workpiece. This process, however, makes it relatively difficult to equalize the pressure applied by the upper and lower punches as such pressure is largely dependent on the amount of pressure applied in the pre-forming process. Moreover, due to the clearance required to remove the spacer, the need to stabilize die placement, and the desirability of preventing lower punch damage, it becomes necessary to structure the lower punch to have a shorter length dimension and the upper punch to a have a longer length dimension than that of the die. Moreover, the die must be partially rotated and the upper punch lowered in order to press the workpiece out of the die—a relatively complex and time consuming operation.
BRIEF SUMMARY OF THE INVENTION
The invention utilizes a sliding frame that drives a lower punch toward the material being worked on and an upper punch toward the material from the other side, and single pressure generating actuator (a force exerter) as a means of simultaneously applying uniform pressure against two opposing sides of the workpiece, thus providing for greater uniformity of the pressure dispersion pattern within the workpiece. Moreover, in cases where the invention is applied to a powdered metal molding press, the invention can significantly reduce the number of operations needed for forming the finished molded product as compared to what was previously required. Further, fewer operations are required to remove the finished workpiece from the die, thus, providing for increased efficiency in press operation.
REFERENCES:
patent: 435212 (1890-08-01), Deane
patent: 4874564 (1989-10-01), Sudani et al.
patent: 5215010 (1993-06-01), Johnson
patent: 5364253 (1994-11-01), Kojima et al.
patent: 63-168296 (1988-07-01), None
Gerrity Stephen F.
Gilman & Berner LLP
Hauptman Lowe
Tsutomu Yamamoto
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