Cutting – Two tool pairs – driver for one pair moves relative to driver... – Successively acting
Reexamination Certificate
1998-12-15
2001-05-29
Peterson, Kenneth E. (Department: 3724)
Cutting
Two tool pairs, driver for one pair moves relative to driver...
Successively acting
C083S615000, C083S618000, C083S623000, C083S639500
Reexamination Certificate
active
06237458
ABSTRACT:
BACKGROUND OF THE INVENTION
Certain manufacturing processes call for operations on two legs of a single piece such as a workpiece having a U-shaped cross-section. The operations are designed to be along a common axis going through that U cross-section. Due to tolerances in the part, as well as the stiffness of the part, the machinery is designed to bring the tools in contact with each leg without deforming the leg prior to the operation, e.g. piercing. A variety of machinery or presses have been devised to alleviate some of the problems encountered in this area. That machinery has included various cylinder and piston combinations for moving opposed tooling against a central workpiece. This tooling, however, suffers from several drawbacks. Among the drawbacks are that the mechanisms for producing sufficient force for the piercing operations are not collinear with the tools themselves, e.g. the punches and anvils. Thus, as more forces are produced, the tools are subject to greater forces which can cant or cock the tooling relative to the desired line of operation. This results in greater tool wear with concomitant reduced tool life, as well as poorer performance due to inaccurate tool alignment, etc. Efforts to reduce some of the problems with unbalanced forces have been countered with larger more massive tools to resist the forces. This, however, can be self defeating in that the tools have to fit within limited space in the factory environment.
SUMMARY OF THE INVENTION
The present invention concerns tooling for operations, e.g. punching, on legs of a U-shaped workpiece whereby the tools, e.g. the punches and anvils, are autoequalized so that the punch will first contact the part, then will actuate anvil (die) into or towards the workpiece to prevent deformation of the workpiece prior to the operation itself. The tooling then allows the sequential operation on the other leg of the workpiece in a similar manner.
One component of the tooling, e.g. either punches or anvils, are mounted on independently reciprocal slide blocks. One of the slide blocks is actuated by fluid pressure against a connective portion. A certain amount of travel of the slide block will result in sufficient force to overcome a mechanical resistor, e.g. a spring, and cause the other component of tooling to draw closer to the first set of tooling. For example, movement of a punch mounted on a slide block will, at a point in travel, cause sufficient force to be generated to cause an anvil mounted on the tooling to travel towards the punch. The resistance of the spring and relative location of the punch and anvil are selected so that the punch and anvil arrive sequentially at the workpiece. The resistance is selected, however, so that the tool that first contacts the workpiece does not substantially deform the workpiece prior to the complementary tool contacting the workpiece. The independently reciprocating slide blocks are mounted within a T-slot of the tooling to resist canting forces generated by the non-collinear systems.
Among the advantages of the present invention are a more compact unit that better resists torquing or canting forces caused by non-collinear pistons with less resultant wear and higher accuracy. Further features and attributes of the present invention are explained in greater detail below.
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BTM Drawing No. 620000A entitled “50.8mm Bore×50mm Stroke Hand Held Unit w/.18 TL Tooling” having T-slot and offset piston (offered for sale or publicly disclosed around 1991).
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Dennison Glenn M.
Kruger Dean J.
Miller Michael D.
BTM Corporation
Harness & Dickey & Pierce P.L.C.
Peterson Kenneth E.
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