Electric heating – Metal heating – Cutting or disintegrating
Patent
1985-12-03
1987-12-08
Pellinen, A. D.
Electric heating
Metal heating
Cutting or disintegrating
219 69R, B23H 702
Patent
active
047119810
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an initial hole forming device for forming an initial hole through a metallic workpiece to receive the wire electrode of an electrical discharge machine using a wire electrode (referred to as "wire-cut electrical discharge machine" hereinafter) and, more particularly, to an initial hole forming device adapted for disposition adjacent to the wire electrode guiding unit of a wire-cut electrical discharge machine.
BACKGROUND ART
A hole for receiving a wire electrode therethrough, namely, an initial hole, must be formed at a predetermined position on a workpiece prior to wire-cut electrical discharge machining. The initial hole must be formed at a position as near as possible to the wire guide of the wire-cut electrical discharge machine. When an initial hole is formed near a wire-cut starting position, the wire electrode can be inserted through the initial hole immediately after the initial hole has been formed, to start wire-cut electrical discharge machining.
However, the conventional initial hole forming means is disposed as far away as possible from the wire electrode guiding unit of the electrical discharge machine in order to prevent interference between the initial hole forming means and the wire electrode guiding unit. Consequently, in some cases, the wire electrode guiding unit cannot be moved relative to the workpiece to insert the wire electrode through the initial hole formed in the workpiece by the initial hole forming means. That is, inconveniently, the initial hole can be formed in the workpiece only within a particular limited area. Accordingly, it is desired to dispose an initial hole forming device adjacent to the wire guiding unit. However, when an initial hole forming device is disposed adjacent to the wire guiding unit, the wire guiding unit may interfere with the initial hole forming device in that the wire guiding unit is displaced from the normal position for forming a tapered hole or the like by the wire electrode. Therefore, such disposition of the initial hole forming device requires an appropriate interference preventing means to prevent damage to the machine.
DISCLOSURE OF THE INVENTION
Accordingly, it is an object of the present invention to provide an initial hole forming device provided with interference preventing means and capable of being disposed near the wire guiding unit of a wire-cut electrical discharge machine.
The present invention provides an initial hole forming device for an electrical discharge machine having wire guiding means for guiding a wire electrode and vertical feed means for moving the wire guiding means vertically toward and away from the workpiece, comprising: frame means attached to the vertical feed means; an initial hole forming head attached to the frame means so as to be vertically slidable relative to the frame means and provided at the lower end thereof with a rotary chuck for holding a hollow bar electrode; means for vertically shifting the initial hole forming head on the frame means between two positions, namely, an initial hole forming position near the wire guiding means and a resting position to which the initial hole forming head is retracted upward from the initial hole forming position; and position detecting means provided on the frame means and capable of detecting the arrival of the initial hole forming head at the initial hole forming position and at the resting position. In this configuration, the wire guiding means cannot be moved laterally, except when the initial hole forming unit is retracted from the working position, namely, the initial hole forming position, to the resting position, and hence interference between the initial hole forming head and the wire guiding means is prevented. Furthermore, it is also possible to interlock the initial hole forming device employing a hollow bar electrode and the electrical discharge machine by interconnecting a numerical control (NC) device, which is used for the programmed control of the machining work of the electrical discharge ma
REFERENCES:
patent: 3609279 (1971-09-01), Giesbrecht
patent: 3891819 (1975-06-01), Ullmann et al.
patent: 4387284 (1983-06-01), Nicholas et al.
patent: 4518842 (1985-05-01), Obara
patent: 4598189 (1986-07-01), Inoue et al.
Aso Toshiyuki
Ishibashi Tamotu
Evans Geoffrey S.
Fanuc Ltd.
Pellinen A. D.
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