Electric heating – Metal heating – Cutting or disintegrating
Reexamination Certificate
1999-10-08
2001-06-12
Evans, Geoffrey S. (Department: 1725)
Electric heating
Metal heating
Cutting or disintegrating
Reexamination Certificate
active
06246024
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a wire electric discharge machining apparatus for machining a workpiece by generating electric discharges between the workpiece and a wire electrode traveling vertically between a pair of wire guide devices, while moving the workpiece relative to the traveling wire electrode. More particularly, the present invention relates to a wire electric discharge machining apparatus having an arm for supporting a lower wire guide device passing through the wall of a work tank.
BACKGROUND OF THE INVENTION
Generally, a lower wire guide device positioned inside a work tank of a wire electric discharge machine is supported at the end of a horizontally extending arm. The arm is fixed to a side surface of a column, for example, at a base end of the arm, and passes through an elongated hole formed in one of the work tank walls. An opening of the elongated hole normally extends in the X-axis direction and the arm extends in the Y-axis direction so that the work tank can move within the X-Y plane relative to the arm. The elongated hole is sealed in a fluid tight manner by a slide plate having a hole through which the arm passes. If the arm is long, there are large variations in the position of the lower wire guide device due to bending in a direction perpendicular to the arm.
U.S. Pat. No. 5,897,791 discloses a wire electric discharge machine having a mechanism for driving a lower wire guide device positioned inside a work tank within the X-Y plane. With this type of wire electric discharge machine, there is no need for an arm for attaching the lower wire guide mechanism, which obviously means that there is no need to seal an arm. A unit including a servo motor, ball screw, guide rail, position sensor, etc. is positioned inside a work tank filled with dielectric fluid, so they are covered in a fluid-tight manner by bellows. However, this unit is heavier than the conventional arm, making it necessary for a mechanism supporting the unit to be sufficiently large. Great care must be taken with respect to protecting the drive mechanism from invasion by dielectric fluid.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a wire electric discharge machine in which a lower wire guide device is positioned as close as possible to a guide mechanism for the lower wire guide device, to ensure accurate positioning of the lower wire guide device.
Another object of the present invention is to provide a wire electric discharge machine that does not require protection against dielectric fluid invasion for the drive mechanism of a lower wire guide device.
Additional objects advantages and novel features of the invention will be set forth in the description that follows and will become apparent to those skilled in the art upon reading His description or practicing the invention. The objects and advantages of the invention may be realized and attained by practicing the invention as recited in the appended claims.
In order to achieve the above objects and other, a wire electric discharge machining apparatus of the present invention for machining a workpiece using a wire electrode traveling vertically between upper and lower wire guide devices may comprise:
a work tank in which the lower wire guide device and the workpiece are disposed,
a lower wire guide drive unit disposed outside the work tank for driving the lower wire guide device horizontally in a direction of a first axis,
a connecting shaft connecting the lower wire guide device and the lower wire guide drive unit,
a first guide rail, extending from the outside to the inside of the work tank in the direction of the first axis and movable relative to the work tank in the direction of a second axis perpendicular to the first axis, and
a moveable support, moveable along the first guide rail, for supporting the lower wire guide.
It is preferable that the moveable support includes a pair of linear motion bearing rails provided on the upper surface of the first guide rail extending in the direction of the second axis, and a pair of linear motion bearings that engage the pair of linear motion bearing rails for movably supporting the lower wire guide device.
It is preferable that the wire electric discharge machining apparatus comprises second guide rail extending in the direction of the second axis, a linear motion bearing rail provided on an upper surface of the second guide rail, and a linear motion bearing engaging the linear motion bearing rail for supporting a tip end of the first guide rail.
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patent: 5070224 (1991-12-01), Töpter et al.
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patent: 5111016 (1992-05-01), Lodetti et al.
patent: 5171955 (1992-12-01), Hosaka et al.
patent: 5243165 (1993-09-01), Hosaka
patent: 5897791 (1999-04-01), Hayakawa
patent: 0 707 917 A1 (1996-04-01), None
patent: 0 779 124 A1 (1997-06-01), None
Devinsky Paul
Evans Geoffrey S.
McDermott & Will & Emery
Sodick Co. Ltd.
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