Cutting – Means to drive or to guide tool – With simple rectilinear reciprocating motion only
Reexamination Certificate
1999-03-17
2001-01-09
Rada, Rinaldi I. (Department: 3724)
Cutting
Means to drive or to guide tool
With simple rectilinear reciprocating motion only
C083S698910, C083S699410, C083S824000
Reexamination Certificate
active
06170375
ABSTRACT:
This invention relates to devices for shaping, trimming, and punching sheet metal or the like utilizing what are referred to in the trade as bump cams.
BACKGROUND OF THE INVENTION
In conventional bump cams, a driver is pushed downwardly by an upper die into the bump cam housing. The driver has an inclined lower end which engages a complimentary inclined end of a tool holder. As the driver moves downwardly, the inclined surfaces cause a tool carried by the tool holder to be shifted outwardly to punch a hole, for example, in the sheet metal workpiece. After a period of time, the laterally directed loading imposed on the tool holder by the inclined face of the driver causes a wearing of the bearing surfaces between the tool holder and the bump cam housing, and the tool carried by the tool holder will drift off center so that the hole being punched will not be in the proper location.
In addition, the construction of conventional bump cams causes a high unit loading at the bearing surfaces within the bump cam that leads to rapid wear and shorter cam life.
SUMMARY OF THE INVENTION
I have designed a bump cam that reduces or substantially eliminates the abuse of the tool holder by the driver which formerly lead to off-center operation of the tool held by the tool holder. In addition, my design enables the alteration of the speed of tool movement and loading of the bump cam without disturbing the design of the tool holder.
These desirable results are obtained by utilizing a sacrificial force transmitting block between the driver and the tool holder which essentially eliminates the lateral loading on the tool holder which was heretofore imposed by the inclined face of the driver engaging a complimentary face of the tool holder. One portion of the sacrificial block has an inclined surface complementing the inclined surface of the driver and another portion floatingly engages the tool holder to push it outwardly without imposing a lateral loading thereon. As a result, my improved bump cam can operate over long periods without causing a tool carried by the holder to be laterally displaced from its proper position vis-a-vis the workpiece.
In addition, when the sacrificial block has become sufficiently worn at its bearing surfaces to impair operation of the bump cam, the block can be simply replaced in the bump cam at a much lower cost than replacing the entire bump cam, as was necessary in the conventional bump cams of the prior art.
Additionally, my design allows an increase in the tonnage capacity of the bump cam without a massive increase in the size of the unit. This is accomplished by increasing the surface area at the inclined interface between the driver and the sacrificial block and does not disturb the tool holder.
REFERENCES:
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patent: 3473425 (1969-10-01), Foist et al.
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patent: 3589226 (1971-06-01), Shadowens, Jr.
patent: 4471680 (1984-09-01), Gerhart
patent: 4621512 (1986-11-01), Tachikawa et al.
patent: 4726270 (1988-02-01), Lucas
patent: 5038599 (1991-08-01), Wellman
patent: 5099708 (1992-03-01), Chung
patent: 5101705 (1992-04-01), Matsuoka
patent: 5197368 (1993-03-01), Meyer et al.
patent: 5410932 (1995-05-01), Moellering
patent: 5678468 (1997-10-01), Bonet et al.
Document entitled External Cam Unit Information, IEM Division of Connell Limited Partnership (9pages, double-sided), 1992.
Brooks & Kushman P.C.
Flores-S{acute over (a)}nchez Omar
LaMina, Inc.
Rada Rinaldi I.
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