JPS61284320A - Wire electric discharge machining method - Google Patents

Abstract

PURPOSE:To protect a surface layer part on a work from corrosion due to an electrolytic current, by performing wire electric discharge machining under a condition that the work of cemented carbides or the like closely attaches to its upper and bottom surfaces a thin conductive metallic plate. CONSTITUTION:The method, closely attaching metallic plates 1, 1' of stainless steel, brass, etc. with less generation of rust to upper and bottom surfaces of a cemented carbide plate 2 of tungsten carbide or the like, performs electric discharge machining by a wire electric discharge machine in machining fluid of about 10<4>-10<6>OMEGA.cm specific resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is primarily concerned with improving the wire electrical discharge machining method for workpieces made of cemented carbide such as tungsten carbide.

[Conventional technology]

Conventional wire electrical discharge machining uses a specific resistance of 10 to 10Ω as machining fluid.
・The workpiece is immersed in the machining fluid using ion-exchanged water of about 100 ml of ion-exchanged water, and electrical discharge machining is performed using a wire electrode.

[Problem that the invention seeks to solve]

In this conventional wire electric discharge machining method, a voltage applied between the wire electrode and the workpiece causes a minute current to flow from the wire electrode to the workpiece surface via the machining fluid. This esl! l! ta<Electrolytic Tfttl) IIC -) The surface layer of the Che crop undergoes electrolytic corrosion. Sometimes, when the workpiece is a superalloy, the cobalt acts on the cobalt layer, which is the binder of the cemented carbide, and the cobalt is electrolytically extracted, causing a cobalt removal phenomenon, which destroys the fabric structure in the surface layer of the workpiece, and changes the properties of the cemented carbide. There was a problem that it caused deterioration. As a countermeasure to this problem, even if a machining fluid with extremely high resistivity (fsK) that is close to pure water is used, ion generation during machining causes ion dissolution into the machining fluid, making it impossible to achieve complete insulation. Corrosion due to electrolytic current could not be avoided.

[Means for solving problems]

The present invention aims to solve these problems and provide an excellent wire electrical discharge machining method that can almost completely prevent corrosion of the surface layer due to electrolytic current. The workpiece is made of cemented carbide, which is characterized by protecting Table 1fAIIIS of the workpiece from corrosion caused by electrolytic flow, by applying wire electrical discharge machining to the top and bottom surfaces of the workpiece, such as a cemented carbide, with a metal plate in close contact with the top and bottom surfaces of the workpiece. Alloy wire electrical discharge machining method. The metal plate to be brought into close contact with the workpiece is not particularly made of metal as long as it is electrically conductive and can be subjected to electrical discharge machining, but stainless steel plates, brass plates, etc., which are less susceptible to rust, are preferable. There is also no particular restriction on the thickness of the metal plate, but it is 0.01
If the thickness is less than 1 km, burrs will appear during discharge, so it is practical to use one with a thickness greater than that. The metal plate is usually brought into close contact with the upper and lower surfaces of the workpiece by means such as clamps.

[Effect]

In this invention, the workpiece and the metal plate are integrally subjected to electric discharge machining while being in close contact with each other. At this time, an electrolytic current is generated between the workpiece, the gold 1j4 plate, and the wire electrode, but corrosion mainly occurs on the surface of the metal plate, and the surface layer of the workpiece is almost free from electrolytic corrosion.

〔Example〕

The example company tungsten carbide cemented carbide plate (2) shown in the drawings was inserted into a stainless steel gold digger W (1) and (1).
', and electrical discharge machining is carried out in a machining fluid with a specific resistance of 1O to 0Ω·α. In the figure, (3) is a wire electrode, (4) is a wire guide, (5) is a machining trajectory after machining, and (6) is a roller.

In this example, gold 1411 plate (1), cemented carbide plate (2
] Approximately 1.5 to 2.5 ff of galvanic corrosion was observed from the processed end surface on the surface of the Kanejima plate (1), as shown in the drawing table.
If (1)' is brought into close contact with cemented carbide (2) K, it will be 15 μm or more.
The corrosion was only about 50P, and the degree of corrosion could not be improved to any degree.

〔Effect of the invention〕

As described above, the present invention has an excellent effect in that electrolytic corrosion of the surface layer of a workpiece can be significantly suppressed by the simple measures described above. .

[Brief explanation of drawings]

The drawings are explanatory diagrams showing an embodiment of the wire electrical discharge machining method of the present invention.

Claims (1)

[Claims] 1) The surface layer of the workpiece is protected from corrosion due to electrolytic current by performing wire electrical discharge machining with metal plates in close contact with the top and bottom surfaces of the workpiece, such as cemented carbide. Cemented carbide wire electrical discharge machining method.