JPS63272420A - Wire electric discharge machining method - Google Patents

Abstract

PURPOSE:To make it possible to automate an electric discharge machining process by jetting liquid containing large particles locked in a machined groove in a workpiece, onto the workpiece so as to prevent a core from dropping even though the remaining part to be cut becomes small, thereby an energizing path is ensured. CONSTITUTION:When a machining process is nearly completed so that the final remaining part to be cut 2-3 becomes less, particle mixed liquid 4 is jetted from a nozzle 3 onto a workpiece 2. The size of particles which are of various kinds mixed and contained in the liquid is such that they are locked in a machined groove 2-2. The particles 4-1 locked in the machined groove 2-1 give wedge action as obtained by a wedge so as to prevent a core 2-4 from dropping. If the material of particles is electrically conductive, the particles themselves establish an electrical path leading to the core 2-4, and therefore, even though the final remaining part 2-3 to be cut, becomes narrow, it is possible to ensure an electrical path necessary for completing the electric discharge machining process.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a wire electrical discharge machining method, and particularly to a wire electrical discharge machining method when there is a portion (hereinafter referred to as a "core") to be cut out from a workpiece.

[Conventional technology]

FIG. 4 shows a workpiece immediately before the end of machining when there is a portion to be cut out from the workpiece in wire electric discharge machining. In FIG. 4, 1 is a wire serving as an electrode for electrical discharge machining, 2 is a workpiece, 2-1 is a start hole drilled at the starting point of electrical discharge machining, 2-2 is a machined groove drilled by electrical discharge machining, 2-3 is the final uncut portion, 2-4 is the core, and 2-5 is the outer frame. FIG. 6 is an enlarged view of part A in FIG. 4. As the electrical discharge machining progresses and the final uncut portion 2-3 becomes small, the final uncut portion 2-3 breaks due to the weight of the core 2-4, and as shown in FIG. 4 falls. Since it is not cut by electrical discharge machining but is broken by mechanical force, both broken surfaces 2-6 are uneven, which is unfavorable from the viewpoint of processing accuracy or appearance. Further, even if the core 2-4 does not fall, it may tilt and pinch the wire, making it impossible to feed the wire or, in some cases, cutting the wire. In order to ensure that the final uncut portion 2-3 is cut by electrical discharge machining to the end rather than by breakage, ■ Preventing the core 2-4 from falling ■ Electric discharge machining of the final portion It is necessary to satisfy the condition of ensuring that the core 2-4 is energized until it is finished. The reason why condition (2) is necessary is as follows. The discharge is performed by applying a voltage between the wire 1 and the workpiece 2. When electrical discharge machining approaches the end, the current to the core 2-4 is applied to the area surrounding the outside of the core 2-4 across the machining groove 2-2 (from the outer periphery, that is, the outer frame 2-5, to the final cut). Remaining part 2-3
done through. Therefore, the less the final uncut portion 2-3 remains, the more difficult it becomes to energize the core 2-4, and when the final portion is cut, satisfactory energization is not performed. As a result, the machining accuracy will deteriorate, so in order to improve the machining accuracy, it is necessary to prevent the core 2-4 from falling until the last part is finished with electrical discharge machining as described above. At the same time, it is necessary to secure a current-carrying path. Therefore, conventionally, as shown in FIG. 7, for example, a magnet piece 5 has been used to satisfy the conditions (1) and (2). That is, when the electrical discharge machining reaches the state shown in FIG. 4, the machining is temporarily interrupted. Then, as shown in FIG. 7, the magnet piece 5 is placed at a position straddling the processed groove 2-2. Since the magnet piece 5 attracts the core 2-4 on one side and the outer frame 2-5 outside the processed groove 2-2 on the other side, the core 2-4 is prevented from falling. Ru. Electricity is supplied from the outer frame 2-5 to the core 2-4 not only through the final uncut portion 2-3 but also through the magnet piece 5, so that only a small amount of the final uncut portion 2-3 remains. Even when this happens, the magnet piece 5 will ensure the required current conduction path. Another conventional technique involves temporarily suspending machining when the state shown in FIG. 4 is reached, inserting a conductive clip into the machining groove 2-2, and then restarting machining. In this example, it acts to prevent the clip from falling and is also crowded with conductive particles.

[Problem that the invention seeks to solve] However,
All of the above-mentioned conventional techniques had the problem that the electrical discharge machining had to be temporarily interrupted and the magnet pieces 5 had to be placed or the clips inserted manually, which hindered automation. The present invention aims to solve the above problems. [Means for Solving the Problems] In order to solve the above-mentioned problems, in the wire electrical discharge machining method of the present invention, a liquid mixed with particles of a size that is retained in the machining groove 2-2 is applied to the workpiece. We decided to include the process of applying body 2.

[For production]

If the particles retained in the processed groove 2-2 are placed on the core 2-4, the particles themselves form an electrically conductive path.

【Example】

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. When the machining process approaches the end and the final uncut portion 2-3 is reduced (when the state shown in Fig. 4 is reached), as shown in Fig. 1, the particle-containing liquid is discharged from the nozzle 3. 4 is spouted and applied to the workpiece 2. Since no manpower is required to carry out this process, there is no risk of electric shock, and there is no need to temporarily interrupt electrical discharge machining. Automation is therefore possible. The particles 4-1 are mixed in various sizes so as to be retained in the processed grooves 2-2. FIG. 2 shows a state in which particles 4-1 are locked in the processing groove 2-2 of the workpiece 2. As shown in FIG. Machining groove 2
The particles 4-1 locked in the core 2-2 prevent the core 2-4 from falling through the same action as a wedge. If the material of the particles 4-1 is made conductive, the particles 4-1 themselves will form a conductive path from the outer frame 2-5 to the core 2-4, so the final uncut portion 2-3 Even if it becomes narrow, it is possible to secure the current conduction path necessary to complete electrical discharge machining to the last part. In addition, if the above-mentioned energizing path is secured by another means, it is sufficient for the particles 4-1 to simply act to prevent falling, so particles 4-1 may be made of a non-conductive material (e.g., ceramics, plastics). It may be something you have. FIG. 3 is a diagram showing the workpiece at the end of machining. After applying the particle-containing liquid 4 to the workpiece 2, the particles 4-1 are locked in the processing groove 2-2, so there is no fear that the core 2-4 will fall or tilt, and the required Since the energizing path is secured, the final uncut portion 2-3 is left as shown in Figure 3.
It is possible to cut cleanly up to the last part using electrical discharge machining.

【Effect of the invention】

As described above, the wire electrical discharge machining method of the present invention includes the step of applying a liquid mixed with particles of various sizes that are retained in the machining groove to the workpiece during electrical discharge machining. Even if the final uncut portion 2-3 approaches the end of machining, the core 2-4 is prevented from falling and the core 2-3 is
-4 can now be automatically secured.

[Brief explanation of drawings]

Figure 1: A diagram showing a state in which particle-containing liquid is applied to a workpiece just before the end of machining. Figure 2: A diagram showing a state in which particles are locked in the machining groove of a workpiece. Figure...Figure 4 shows the workpiece at the end of machining...
・Figure 5 shows the workpiece just before the end of machining...Figure 6 shows how the cut core falls...Figure 7 is an enlarged view of part A in Figure 4... - In the diagram showing the conventional example, 1 is the wire, 2 is the workpiece, 2-1 is the start hole, 2-2 is the machined groove, 2-3 is the final -7 = uncut portion, 2-4 is the middle 2-5 is an outer frame, 3 is a nozzle, 4 is a particle-containing liquid, 4-1 is a particle, and 5 is a magnet piece.

Claims (1)

[Claims] In a wire electrical discharge machining method in which a voltage is applied between a wire serving as an electrode and a workpiece to produce an electrical discharge and the workpiece is machined into a desired shape, the wire is locked in a machining groove during electrical discharge machining. A wire electrical discharge machining method comprising the step of applying a liquid mixed with particles having a size of about 100 to 1000 to 1000 to 1000, to a workpiece.