Electric heating – Metal heating – Cutting or disintegrating
Reexamination Certificate
1999-09-20
2001-03-13
Evans, Geoffrey S. (Department: 1725)
Electric heating
Metal heating
Cutting or disintegrating
Reexamination Certificate
active
06201205
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to a wire-cut electric discharge machine, and in particular, to a wire-cut electric discharge machine capable of forming a workpiece with a taper including an extendable pipe which is provided between a frame and an upper wire guide to guide a wire electrode therein.
2. Description of Related Art
Conventionally, a wire-cut electric discharge machine is equipped with a wire electrode, a pair of an upper wire guide and a lower wire guide that supports the wire electrode across a workpiece, and a table moving mechanism that moves a table supporting a workpiece thereon in a horizontal direction at substantially a right angle relative to the length of the electrode. In electric discharge machining, the wire electrode is reeled out, guided near the surface of a workpiece by the upper and lower wire guides, and the table moving mechanism moves the table supporting the workpiece thereon in the horizontal direction. Arc electric discharging is repeatedly performed in between the wire electrode and the workpiece in insulated machining fluid, for example, resulting in electric discharge machining the workpiece.
Normally, the pair of wire guides is installed vertically, and the wire electrode guided by the wire guides, is also kept in tension vertically. When a workpiece is electrical discharge machined as above, a surface of the workpiece becomes vertical, however, when the pair of the wire guides is relatively moved in the horizontal direction, the wire electrode becomes slanted, and a processed surface of the workpiece can be electric discharge machined so that it can be tapered relative to a vertical direction.
The applicant of this application proposed a wire-cut electric discharge machine disclosed in Japanese Laid-Open Patent Publication No. 5-277836. In this wire-cut discharge machine, an automatic connection device that automatically connects a broken wire electrode is fixed to a frame at an upper part of the upper wire guide, and a vertically extendable pipe is provided in between the upper wire guide and the automatic connection device. Both ends of the pipe are respectively fixed to the automatic connection device and the upper wire guide. A wire electrode extending from the automatic connection device passes through the pipe and extends in the upper wire guide. The upper wire guide can be moved upward and downward by the wire guide lifting mechanism.
Since the wire-cut discharge machine provides the pipe, the machine gains a function of enabling the wire electrode to be guided to the upper wire guide on the occasion when a broken wire electrode is automatically connected. Therefore, the automatic connection device is mounted to the frame fixedly above the upper wire guide. Compared with the original conventional machine where the automatic connection device is raised and lowered along with the upper wire guide, a wire guide lifting mechanism is smaller, and deterioration of the automatic connection device due to stains of machining fluid can be prevented.
When workpieces are electrical discharge machined so that their processed surfaces can be tapered relative to the vertical direction, the wire electrode between the pair of wire guides needs to be inclined from the vertical direction. For this purpose, the upper wire guide needs to be moved horizontally because it is difficult to move the lower wire guide only in the horizontal direction.
In the wire-cut electric discharge machine described in Japanese Laid-Open Patent Publication No. 5-277836, however, both ends of pipe are fixedly linked to the automatic connection device and the upper wire guide respectively, and the upper wire guide is not allowed to move horizontally. Therefore, electrical discharge machining cannot be applied to workpieces, so that their processed surfaces become tapered inclined from the vertical direction.
To allow the upper wire guide to move horizontally, it is possible to omit the pipe in the machine. However, this is not desirable from a safety standpoint because the wire electrode therebetween is exposed to the outside, and the automatic connection device may not able to operate correctly because the wire electrode is not guided to the upper wire guide.
On the other hand, it is possible to make the automatic connection device rise and lower along with the upper wire guide by installing the automatic connection device to the upper wire guide. However, it becomes difficult to shrink the size of the wire guide lifting mechanism and prevent the automatic connection device from deteriorating due to stains of machining fluid.
SUMMARY OF THE INVENTION
A first object of the invention is to provide a wire-cut electric discharge machine that enables a surface of a workpiece to be tapered by introducing a hollow member to allow a wire electrode to be inserted in between a frame and a wire guide that is on an upper part thereof, and by connecting either end of the hollow member so that the pipe can oscillate. A second object of the invention is to provide a wire-cut electric discharge machine that is not subject to receiving an electrical shock by covering the hollow member in which the wire electrode is inserted with an insulated material.
To accomplish the first object, the invention provides a wire-cut electric discharge machine that includes a frame, a wire electrode to be supplied from the frame, and a first wire guide is disposed upstream of a workpiece. The first wire guide guides the wire electrode. A second wire guide is disposed downstream of the workpiece opposite to the first wire guide. The second wire guide guides the wire electrode. A first moving device moves the workpiece relative to said first and second wire guides. A second moving device moves the first wire guide in a direction that is substantially perpendicular to the lengthwise of the wire electrode. A hollow member is mounted between the frame and the first wire guide. The hollow member enables the wire electrode to pass through therein. The hollow member is able to extend and contract in a lengthwise direction of the hollow member. A connecting mechanism connects one end of the hollow member to the frame, and connects another end of the hollow member to the wire guide. The connecting mechanism includes of a first connecting member and a second connecting member. The first connecting member is attached to the frame. The first connecting member enables one end of the hollow member to oscillate. The second connecting member is attached to the first wire guide. The second connecting member enables another end of the hollow member to oscillate.
In the case where electrical discharge machining is performed with the first and second wire guides set on an identical axis relative to the length of the wire electrode, a workpiece is machined so that a processed surface becomes parallel to a vertical direction. On the other hand, where electrical discharge machining is performed after the second moving device moves the first wire guide to set the first and second wire guides in different positions relative to the length of the wire electrode, a workpiece is machined so that a processed surface becomes tapered toward a direction to which the first wire guide moves.
Namely, since the wire-cut electric discharge machine of this invention has been equipped with the second drive device and the connecting mechanism, it can move the first wire guide in a direction at right angles substantially to the length of the wire electrode, wherein both ends of the hollow member are kept connected to the frame and the first wire guide respectively. Hereby, the wire electrode guided by the first and second wire guides is kept inclined relative to a direction to which the first wire guide moves, and it is possible to carry out electrical discharge machining so that a surface of a workpiece to be processed can be tapered with an inclination relative to a direction to which the first wire guide moves. The wire electrode has high safety since it is covered with a hollow member in order not to b
Brother Kogyo Kabushiki Kaisha
Evans Geoffrey S.
Oliff & Berridg,e PLC
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