Chucks or sockets – Socket type – Friction grip
Reexamination Certificate
2000-01-12
2001-07-17
Bishop, Steven C. (Department: 3722)
Chucks or sockets
Socket type
Friction grip
C029S447000, C403S273000, C408S226000, C409S234000
Reexamination Certificate
active
06260858
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of Invention
This invention relates to heat shrink tool assemblies wherein a work piece such as a drill bit or cutting tool is positioned with a tool chuck by means of heating the chuck thereby causing it to expand whereby the tool shank is inserted within the chuck and held in place by the chuck when it has cooled and shrunk around the tool shank.
2. Description of Prior Art
It is known in the art to utilize heat shrink tool assemblies in high speed industrial applications. The prior designs have utilized unitary chucks having an inner diameter slightly smaller than the exterior diameter of the shank of the cutting tool or other work piece. During use the tool chuck is heated, typically by means of induction heating, causing the chuck to expand a sufficient amount to allow the tool shank to be inserted within the chuck. The tool is then allowed to cool during which the thermal contraction of the chuck exerts a uniform pressure on the tool shank, allowing the chuck to shrink down around the tool shank to securely lock or hold the shank in place. It has long been recognized that these types of heat shrink tool assemblies provide an improvement over standard milling chucks or collet chucks.
Various prior approaches to heat shrink tool assemblies are shown in Zale, U.S. Pat. No. 2,942,891; Yamaguchi, et al., U.S. Pat. No. 5,140,739; Teeslink, U.S. Pat. No. 5,267,384, Marquert; U.S. Pat. No. 5,280,671; Krämer, et al., U.S. Pat. No. 5,277,435; Cook, U.S. Pat. No. 5,311,654 and Cook, U.S. Pat. No. 5,582,494.
These prior devices all suffer from the same shortcoming when it is desired to remove the tool from the chuck. In order to remove the tool the chuck is re-heated to expand the opening. During the heating process the chuck transfers heat to the tool shank itself. The expanding tool shank can create problems with the removal of the tool from the chuck, even resulting in the tool remaining grasped by the chuck and requiring a significant force to remove the tool.
A need therefore exists for a heat shrink tool assembly which allows for the easy and quick removal of the tool from the chuck.
SUMMARY OF THE INVENTION
The present invention comprises a new insulated, shrink fit tool system and method of assembly, which utilizes an insulating sleeve within the internal opening of a heat shrink tool holder wherein the insulating sleeve is made of chemically pure titanium or a titanium alloy having a thermal conductivity of 4 to 5 times less than that of the tool holder. In use the tool holder, preferably constructed from nickel-chromium steel, is heated by means of an induction heating system. As the tool holder is heated it expands outwardly thereby enlarging or increasing the internal diameter of the holder. The internal section of the holder is lined with an insulating sleeve prepared from titanium or a titanium alloy having a thermal conductivity less than the holder. The insulating sleeve is brazed, or otherwise joined to the inner wall of the holder so that the expansion of the holder during heating will result in a simultaneous, and equal expansion of the inner diameter of the insulating sleeve. The shank of a cutting tool is than inserted within the thermal insulating sleeve of the holder and the holder is allowed to cool. As the holder cools it exerts a uniform pressure on the tool shank positioned within the thermal insulating sleeve resulting in a tight, uniform and rigid concentric coupling of the cutting tool and chuck.
When it is desired to remove the tool from the holder the holder is again heated by induction heating. The holder, including the insulating sleeve, expands outwardly thereby allowing the tool shank to be pulled from or otherwise removed from the tool holder. Due to its lower thermal conductivity the insulating sleeve does not transfer the heat to the tool which allows for the removal time to be shortened and also allows for the removal of the tool by the machine operator.
The new insulated, heat shrink tool holder of the subject invention is manufactured by means of preparing a thermal insulating sleeve out of chemically pure titanium or 6-4 titanium alloy, wherein the external diameter of the sleeve is approximately 0.001″ inches less than the internal diameter of the tool holder. The thermal insulating sleeve is inserted within the tool holder and the tool holder and sleeve are then joined together by means of explosive bonding or by brazing. Thereafter, the thermal insulating sleeve will expand or contract in unison with the tool holder as the tool holder is heated or cooled.
REFERENCES:
patent: 2942891 (1960-06-01), Zale
patent: 3382563 (1968-05-01), Barroil et al.
patent: 4499646 (1985-02-01), Allor et al.
patent: 4516787 (1985-05-01), Venable
patent: 4602411 (1986-07-01), Brown
patent: 5140739 (1992-08-01), Yamaguchi et al.
patent: 5267384 (1993-12-01), Teeslink
patent: 5277435 (1994-01-01), Kramer et al.
patent: 5280671 (1994-01-01), Marquart
patent: 5311654 (1994-05-01), Cook
patent: 5582494 (1996-12-01), Cook
patent: 5979912 (1999-11-01), Cook
patent: 6035512 (2000-03-01), Cook
Bishop Steven C.
Fulwider Patton Lee & Utecht LLP
Induction Technologies
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