Metal deforming – Tool and/or tool holder – Having unitary tool-face
Reexamination Certificate
2001-10-09
2002-09-17
Jones, David (Department: 3725)
Metal deforming
Tool and/or tool holder
Having unitary tool-face
C072S481100, C072S462000, C072S482200
Reexamination Certificate
active
06450004
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to large, heavy duty powered metal forming equipment, and more specifically to a punch holder for use with a hydraulically or otherwise powered metal forming press brake. The present punch holder provides for the transfer of mechanical force from a separate activator mechanism to operate a series of otherwise independent punch holder clamps, thereby simultaneously engaging or releasing the press brake punches held therein and greatly reducing the time required for configuration changes.
2. Description of the Related Art
Press brakes are conventionally used in metal forming, particularly for forming bends in relatively large and/or thick sheets of metal. Such brakes are almost universally actuated by hydraulics, but may be powered by other means (mechanical, electromechanical, etc.) as desired. These brakes commonly have a relatively fixed, lower table or bed which carries a metal forming die (or series of dies), and a relatively movable upper ram which holds a series of complementary punches. When the machine is activated, the ram with its punches is forced downwardly into the die or dies, bending any metal placed therebetween.
Punches and dies must frequently be changed due to material and workpiece requirements. While die changes are demanded primarily by material thickness demands, punches are subject to a broader variety of demands. A wide variety of punch profiles, and frequent changeovers, are required to address workpiece demands. With reference to the so-called European style of tooling, multiple independent punch holders function as intermediate spacers between the ram and the punches. These punch holders typically utilize two bolts per punch holder to secure a punch by means of a clamp plate. A ten foot long machine typically utilizes sixteen of these independent punch holders. Thus, it can require the loosening of thirty-two separate bolts to release the entire punch series. The installation of new tools can also require the tightening of thirty-two bolts, in order to secure the new punches. Thus, a total of sixty-four separate mechanical actions may be necessary in order to make a complete punch changeover in such a machine.
Accordingly, a need will be seen for a press brake punch holder system which activates the clamps and secures punches, by means of a single mechanism which acts simultaneously upon all of the punch clamps to secure or release the punches as desired, using a single mechanical motion. Two embodiments of the present punch holder are provided, with a first embodiment using a series of laterally disposed wedges for actuating the clamps, and a second embodiment using fluid means (pneumatic or hydraulic pressure).
A discussion of the related art of which the present inventors are aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 3,584,497 issued on Jun. 15, 1971 to William L. Pohjola, titled “Sliding Parallel Ways For Releasing Jammed Press,” describes a series of wedges for installation beneath the dies of a metal forming press or the like. The wedges facilitate release of the press pressure in the event the press actuating mechanism becomes caught on dead center, or overcenter, and cannot be released using standard procedures. In this event, the wedges are knocked loose from their positions, thereby relieving the pressure in the press and allowing the press to be reset normally. Pohjola does not disclose any means of engaging or releasing a series of otherwise independent laterally disposed jaws using his wedges in a punch press, nor do his wedges act laterally, as in the present invention.
U.S. Pat. No. 3,889,515 issued on Jun. 17, 1975 to Walter J. Grombka, titled “Wedging Structure For Presses Or The Like,” describes a similar structure to that of the Pohjola wedge assembly discussed immediately above. Grombka provides powered hydraulic means for adjusting or releasing the positions of his wedges, as well as hydraulic fluid under high pressure between the surfaces of his wedges and adjacent surfaces for reducing friction therebetween. However, the Grombka wedge assembly still functions essentially like the Pohjola assembly, and cannot operate laterally for actuating a series of punch clamps.
U.S. Pat. No. 3,965,721 issued on Jun. 29, 1976 to Gerald V. Roch, titled “Adjustable Die Holder,” describes the use of a series of vertically acting yedges which may be differentially adjusted to compensate for any bending of the die holder bar under-pressure during the bending operation. As in the devices described above, the Roch wedges act vertically, not laterally, and as they are disposed beneath the relatively stationary die, they do not communicate with the multiple punch holder clamps or jaws in any way.
U.S. Pat. No. 4,137,748 issued on Feb. 6, 1979 to Walter J. Grombka, titled “Wedging Structure For Presses Or The Like,” describes a wedge system similar to that of his earlier '515 U.S. Patent discussed further above. The wedge structure of the '748 U.S. Patent includes sealing means capable of preventing blowout under the extremely high hydraulic pressures used. However, the system still operates in essentially the same manner as that of his '515 patent, i. e., vertically, rather than laterally, as in the present invention, and does not provide any means of actuating a series of punch clamps.
U.S. Pat. No. 4,354,374 issued on Oct. 19, 1982 to Hideaki Deguchi, titled “Bending Press,” describes a longitudinally acting wedge system, i. e., along the length or span of the press, for compensating for flexure of the stationary die during bending operations. The Deguchi apparatus is thus more closely related to that of the Roch '721 U.S. Patent, discussed further above, than to the present invention.
U.S. Pat. No. 4,535,689 issued on Aug. 20, 1985 to Ladislao W. Putkowski, titled “Press With Wedge,” describes a system having opposed, longitudinally acting wedges which act to lift the die in the press to compensate for bending of the structure during forming operations. The Putkowski assembly is thus more closely related to that of the Roch '721 and Deguchi '374 U.S. Patents, than to the present invention.
U.S. Pat. No. 4,586,361 issued on May 6, 1986 to Andrei Reinhorn et al., titled “Press Brake Deflection Compensation Structure,” describes a wedge system disposed within the stationary bed of the press, rather than in the movable ram portion, as in the present invention. The Reinhorn et al. assembly includes a tension rod for the lower wedge, to adjust the height and bending of the lower plate in the machine. No lateral wedging or dual action for engaging or releasing a series of punch clamps is provided by Reinhorn et al.
U.S. Pat. No. 4,653,307 issued on Mar. 31, 1987 to Vaclav Zbornik, titled “Bending Tool,” describes a press brake having a linear series of mutually adjacent vertical pins forming the bottom of the die. The pins are adjusted vertically by a wedge assembly, to achieve the desired height for the base of the die. Thus, Zbornik is only directed to vertical adjustment, and does not provide any means of lateral adjustment nor engagement with the upper punch clamps of the brake, as provided by the present invention.
U.S. Pat. No. 4,736,612 issued on Apr. 12, 1988 to Robert L. Russell, titled “Compensating Die Holder,” describes a wedge assembly disposed beneath the relatively stationary die of a punch press or similar machine. The two wedge components are sloped laterally, and while they move laterally relative to one another, the result is vertical adjustment of the upper wedge component, rather than lateral motion of adjusting members, as in the present invention. Russell does not disclose any means of engaging or releasing the punch clamps or jaws in an upper ram assembly, as provided by the present invention.
U.S. Pat. No. 4,895,014 issued on Jan. 23, 1990 to David L. Houston, titled “Failsafe Tool Clamping System For Press Brake,” describes various embodiments
Edmondson Douglas E.
Stover Carl
Jones David
Litman Richard C.
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