JPH0472653B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electric discharge machining apparatus such as a die-sinking electric discharge machining apparatus and a wire-cut electric discharge machining apparatus that performs machining by applying electric discharge to a gap between a machining electrode and a workpiece facing each other.

[Prior art]

In electrical discharge machining, it is necessary to be able to easily detect and adjust the relative position between a machining electrode and a workpiece. Conventional positioning jigs have a predetermined positional relationship with a predetermined reference surface of the workpiece and are equipped with contact detection electrodes, for example, contact detection by energization. , positioning and detection is performed by moving the replaced machining electrode close to and in contact with the detection electrode. The feed accuracy directly affects the accuracy of contact detection, and it was not possible to obtain a higher positioning accuracy of the motor drive device for relative movement.

[Problem solving means]

The present invention was provided in order to improve this positioning accuracy, and the positioning detection tool or the relatively moving drive device is provided with a microscopic drop in the direction in which the detection electrode and the processing electrode at the tip of the positioning detection tool approach each other. It is characterized by providing an electrostrictive material or a magnetostrictive material to be displaced.

〔Example〕

The present invention will be explained below with reference to an embodiment of the drawings.

In FIG. 1, reference numeral 1 denotes a processing electrode, which is detachably attached to the quill 2. 3 is the workpiece,
It is fixedly mounted on the processing table 4. Reference numeral 5 denotes a machining tank which surrounds the machining table 4 and the workpiece 3, and performs electric discharge machining while supplying and storing machining fluid 6 at a depth that covers the workpiece 3 inside. Reference numerals 7 and 8 indicate position detection devices, in which support columns 71 and 81 are fixed with magnetic chucks 72 and 82, and detection electrodes 73 and 83 are provided at the tip of the support columns to protrude above the machining liquid level 6, and the detection electrodes 7
3 and 83 are interposed with electrostrictive materials 74 and 84 to cause slight displacement.

The position detectors 7 and 8 are for detecting a reference position in the X-axis direction, and are fixed in a predetermined positional relationship with a predetermined reference plane of the workpiece 3 by magnetic chucks 72 and 82. Electrodes 73 and 83 are provided parallel to the X-axis in the direction of the processing electrode 1. Of course, a similar detection tool is also provided in the orthogonal Y-axis direction.

Although not shown, the processing tank 5 is provided on a moving table that moves in the X-axis and Y-axis directions,
The workpiece 3 is moved relative to the processing electrode 1 in a desired manner by the drive motor, and positioning is controlled.

The processing electrode 1 is detachably attached to the quill 2, and can be automatically replaced by an automatic electrode replacement device (not shown) or the like.

FIG. 2 is a layout diagram of the position detecting tools 7 and 8, which are positioned in a predetermined positional relationship with the reference surfaces a and b of the workpiece 3 as shown. Position detector 7, 8
The center position p is set at a distance lp from the reference plane a in the X-axis direction, and the position detectors 7 and 8 are provided on axes parallel to the reference plane b with the point p as the center.

Now, to explain the positioning of the processing electrode 1 in the X-axis direction, the electrode 1 is relatively moved onto the central axis between the position detection tools 7 and 8. After that, the processing electrode 1 is moved to the right and left in the X-axis direction. Both are moved relative to each other by a numerical control device. The processing electrode 1 is moved rightward until it comes into contact with the detection electrode 73. Next, it is turned to the left and moved until it contacts the detection electrode 83, and the distance traveled at that time is measured by a numerical control device.

The processing electrode 1 is moved by a motor drive device, but before it comes into contact with the detection electrodes 73, 83, the feed control is switched to the electrostrictive materials 74, 84, and a voltage is applied to the electrostrictive materials 74, 84. Detection control for approaching and touching is performed as the size increases. The amount of approaching movement by the electrostrictive materials 74, 84 can be determined by measuring the voltage applied before contact, and the amount of movement proportional to the applied voltage can be precisely measured depending on the characteristics of the electrostrictive materials used. As described above, the dimensional distance l that the processing electrode 1 moves between the detection electrodes 74 and 84 can be accurately detected and measured by the sum of the movement amount measured by the motor drive and the movement amount measured by the electrostrictive material. can.

Therefore, by moving the processing electrode 1 by l/2 to the right from the position where it contacts the electrode 83, the center of the electrode can be made to coincide with the point p. Also, p
If you move leftward from the point by Lp, the processing electrode 1
The center of can be made to coincide with the reference plane a.

By feeding back the determination of such dimensions to the numerical control drive system, accurate control and electrical discharge machining can be performed.

In addition, the micro displacement characteristics of electrostrictive materials are usually 30μm/
The voltage is approximately 400V, and it is possible to control to within 1μm per 1V of voltage, and the processing accuracy based on this dimension measurement is approximately ±
EDMing of approximately 0.005μm is now possible.

Note that the positioning control can be similarly detected and controlled in the Y-axis direction from the workpiece reference surface b.

〔effect〕

As described above, in the present invention, when replacing a processing electrode, the center of the replaced electrode can always be accurately aligned with the reference position. In particular, we installed an electrostrictive material that moves minutely in the direction in which the detection electrode and processing electrode approach each other at the tip of the positioning detector, and this measures the movement dimension of contact detection, making it easy to reduce the accuracy to 1μ or less. Accordingly, the machining accuracy was approximately 0.005μ. The minute displacement element can be made of a magnetostrictive material, and can be provided in a drive control device that relatively moves the processing electrode. In addition, the detection electrode at the tip of the positioning detector uses electricity to detect contact with the processing electrode, but since the detection electrode is always provided so as to protrude above the surface of the processing liquid in the processing tank, there is no possibility of adhering impurities such as processing debris. Therefore, stable and accurate detection control can be performed at all times without disturbing the current-carrying contact.

The present invention is particularly effective when electrical discharge machining is automatically performed while sequentially replacing machining electrodes using an automatic electrode exchange device.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the implementation operation. 1... Electrode for processing, 3... Workpiece, 5... Processing tank, 6... Processing liquid, 7, 8... Position detection tool, 73, 83... Detection electrode, 74, 84... Electrostriction Material.

Claims (1)

[Claims] 1. A position detection tool provided with a detection electrode that has a predetermined positional relationship with a predetermined reference surface of a workpiece to be subjected to electric discharge machining and faces a machining electrode and that contacts and inspects the machining electrode, In an electric discharge machining apparatus in which position detection is performed by causing relative movement between the machining electrode and the workpiece by a drive device, the position detection tool or the relative movement drive device is configured to detect a position of the tip of the position detection tool. An electric discharge machining apparatus characterized in that an electrostrictive material or a magnetostrictive material is provided to cause a slight displacement in a direction in which a detection electrode and the machining electrode approach each other.