Chucks or sockets – Radially reciprocating jaws – Jaws
Reexamination Certificate
2002-01-04
2004-01-20
Howell, Daniel W. (Department: 3722)
Chucks or sockets
Radially reciprocating jaws
Jaws
C269S266000, C279S004100, C279S133000
Reexamination Certificate
active
06679503
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a chuck unit for a machine tool capable of holding a workpiece at a section which is circular or non-circular.
A conventional chuck unit for a machine tool to be installed on a lathe or the like is usually produced for holding a workpiece having a section that is circular. It may not be possible to hold a workpiece having a section that is a polygon or an irregular shape, except in a chuck with special or customized jaws.
Recently, the machining capabilities of machine tools, such as lathes, have become more complicated and have advanced highly. Various machining operations, such as milling machining, fraise machining, and drilling machining, are possible in addition to mere lathe turning.
For efficient machining, it may be desirable to complete all the machining steps needed on a workpiece in a given machine tool in such a way that a workpiece is subjected to a first routine of machining while held by a first chuck unit, and then is delivered to a second chuck unit facing the first chuck unit. The second chuck unit holds the workpiece by the portion that was machined during the first routine of machining. A second routine of machining is then executed on the portion which has not yet been machined, such as the portion that had been held by the first chuck unit.
In such a case, the portion of the workpiece to be held by the second chuck unit, namely the portion on which the first routine of machining has already been finished, may not always have a circular section. It may have various shapes. In fact, due to increasingly diverse machining operations in recent years, the sectional shape may not be circular in most cases. Nevertheless, it is necessary to execute the second routine of machining while properly holding even such a workpiece.
In a conventional method of using so-called raw jaws, it is possible to machine single use raw jaws for every change of a workpiece. This is not efficient, and the jaws cannot be used to machine various kinds of workpieces. There is a need for a chuck unit capable of properly holding a workpiece having various sectional shapes without troublesome work, such as machining of raw jaws.
German patent No. 19755517 discloses a technique wherein a plurality of workpiece holding rods are provided at a workpiece holding member, such as a jaw. The rods are free to move in a radial direction, and a workpiece having various shapes can be held by such workpiece holding rods. At least two such workpiece holding members need to be provided in a chuck unit to hold the workpiece. The particular structure of the workpiece holding rods and workpiece holding members, and how they are to be driven, and how driving operations of the workpiece holding rod are executed, and the nature of the fixing operation, are problems which remain to be solved.
If the workpiece holding rods and workpiece holding members operate such that every workpiece holding member or workpiece holding rod needs to be moved and driven, then setting and holding the workpiece takes some time. If moving and driving the workpiece holding rod to a predetermined position, and an operation for then fixing the workpiece, are executed with respectively different driving means, it may be necessary to operate driving means at two places concerning each workpiece holding member. The choices are troublesome, and often impractical.
The object of the present invention is to provide a chuck unit for machine tool capable of properly holding a workpiece having various sectional shapes, not limited to a circular section, and capable of executing moving and driving operations and fixing operations using workpiece holding rods, by a simple operation driven from outside the workpiece holding parts, taking the above-mentioned circumstances into consideration.
SUMMARY OF THE INVENTION
It is an aspect of the invention that a chuck unit for a machine tool is capable of holding a workpiece, the chuck unit being installed on a spindle that is rotatably supported. The chuck unit comprises a main body that is free to rotate and drive, defining an axial center. Two or more sliding members are provided on said main body. The sliding members are free to move in a radial direction with respect to said axial center of the main body, through sliding member driving means. A workpiece holding member is provided on said each sliding member. The workpiece holding member is capable of moving together with said sliding member. A plurality of workpiece holding rods are provided on the workpiece holding member. The workpiece holding rods are free to move and drive in the radial direction relative to the axial center. The workpiece holding rods are driven by a fluid cylinder driving means. The fluid cylinder driving means has a cylinder formed in each such workpiece holding member. The workpiece holding rod is engaged with said cylinder and is free to move and reciprocate. A member moving mechanism is provided between the sliding member and the workpiece holding member, such that said respective workpiece holding members are free independently to move and drive in the radial direction by operation of the member moving mechanism. The member moving mechanism has an adjustable screw mechanism rotatably provided between said sliding member and said workpiece holding member, such that the workpiece holding member is free to move and drive with respect to said sliding member in said radial direction, by operating the adjustable screw mechanism. The adjustable screw mechanism has a screw operation portion, operable by a rotating jig, rotatably provided at said machine tool, on an outer peripheral side of said chuck unit. A workpiece end face abutting means is provided at said main body. The abutting means is free to move, drive and become fixed in the axial direction relative to the main body. A workpiece end face abutting face is formed at a top end of said workpiece end face abutting means, at a right angle with respect to said axial center direction of the main body.
The workpiece holding rods as described can hold a workpiece at a portion that has been machined or has various sectional shapes, not limited to shapes having a circular section. Machining is possible on the workpiece, even assuming a machined and/or noncircular sectional shape, without the need for raw jaws to hold an irregular or already machined sectional portion. Thus, a first routine of machining and a second routine of machining can be successively executed with a single machine tool, including first holding one portion of the workpiece while machining another, delivering the workpiece between spindles, and then holding the now-machined portion while machining the portion that was previously held. The efficiency of machining work can be rapidly improved.
The workpiece holding members can be respectively independently moved by the member moving mechanism. This makes it readily possible to hold workpieces that have any of a variety of different sectional shapes. The adjustable screw mechanism of the member moving mechanism has a screw operating portion that is rotatable and drivable by the rotating operation jig . Accordingly, the position of the member moving mechanism can be adjusted mechanically rather than by hand, which contributes to automation of the machining operations.
The workpiece holding member can rapidly be moved to a position approaching the workpiece by the member moving mechanism. It is possible to adapt to a new workpiece diameter by moving the workpiece holding rod, and not necessarily by changing the length of its moving stroke. As a result, the workpiece holding member can be compact.
The workpiece also can be held because the workpiece end face is abutted by the workpiece end face abutting face. Workpieces are securely held even if they have irregular shapes.
According to another aspect, the sliding member driving means has first members that are free to move in the axial center direction, and an engagement portion formed at said first members. The sliding member is connected with said engagement p
Koike Haruhiko
Yamamoto Noboru
Yamazaki Tsunehiko
Duane Morris LLP
Howell Daniel W.
Yamazaki Mazak Kabushiki Kaisha
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