JPS63267122A - Wire-cut electric discharge machining device - Google Patents

Abstract

PURPOSE:To make an erosion rate go up as well as to secure a good finishing surface by performing rough machining, medium machining or finishing work with two types of discharge pulses dirrefent in pulse discharge current value. CONSTITUTION:A working power source 3 is provided with a high current crest value pulse generating circuit 3a and a low current crest value pulse generating circuit 3b whereby two types of pulses are generated, and they are impressed on a gap between a wire electrode 1 and a workpiece 2 via both current-energizing pins 8a and 8b. When a pulse output number of the high current crest value pulse generating circuit 3a is set to N, and that of the low current crest value pulse generating circuit 3b to (n), respectively, the (n) and the N value are set so as to become rough machining n<=N, medium machining n>=N and finishing work n>>N as a working condition with each output number of n and N according to those of rough machining, medium machining and finishing work, thus machining takes place.

Description

[Detailed description of the invention] 1 skin” J-So’s breasts are sad! The present invention relates to a wire cutting machine.

Yoshiki 2μ-! In wire cut electrical discharge machining, the electric discharge pressure generated during machining excire electrodes are excited, so electrical control must be optimized so that the frequency does not resonate with the unique vibration of the wire electrode stretched between the positioning guides. It is known that if this is not done, the width will increase and the number of short circuits will increase, leading to an air discharge and disconnection of the electrode. As a way to prevent the disconnection, the unit pulse width τ is controlled by the control circuit of the unit pulse oscillator. Japanese Patent Publication No. 59-21755 discloses a method of controlling the power density and peak value of a processing pulse based on a pulse signal that oscillates while changing n-s and interval τoff-s and a signal from a peak value control circuit. has been done.

Further, Japanese Patent Application Laid-Open No. 192420/1983 discloses a method in which a discharge energy increasing pulse is incorporated into a pulse train of a predetermined blade unit to maintain a constant amount of machining chips in the machining gap.

Conventional methods and devices control unit pulses temporally to change and control the power density, or control unit pulses in predetermined processing units. This is a method that incorporates discharge energy increasing pulses into the pulse train to keep the amount of intervening chips in the machining gap constant at all times, and does not control pulses corresponding to rough machining, semi-machining, and finishing machining. Therefore, the present invention uses two types of pulses: a pulse with high energy and a large peak value of discharge current, and a pulse with low energy and a small peak value of discharge current. This was done for the purpose of electrical control.

1111111 and 12 ρtμ Further, the inventor carried out experiments and prototype production, and was able to use these two types of discharge pulses for rough machining and semi-machining.

Alternatively, the contents of the finishing process were defined and the optimal electrical control was changed. That is, the low pulse number of Ip is nl I
If the number of pulses with high p is set to N, it is said that it is optimal to set the machining conditions according to the relationship n≦N for rough machining, n≧N for medium 710 machining, and n >> N for finishing machining. The results were obtained.

In this way, the condition of the machining gap is detected and the number of N is reduced depending on the frequency of short circuits in one gap to prevent wire breakage. It is a sum that effectively generates the following. In the case of finishing machining, if the gap is narrow, it will become unstable and there is a risk of wire breakage. Since the smaller pulses are discharged more and more while the gap is wide, the efficiency is improved.

The device of the present invention without an embodiment will be explained using an electrical connection diagram of one embodiment. The wire-cut electric discharge machining device unwinds the wire electrode 1 from a reel of 10,000, and while recovering it by winding it onto the other reel, maintains a predetermined tension between the pair of positioning guides 7a and 7b. Move this guide 7a
, 7b, the workpiece 2 is opposed to the axis of the wire electrode 1 from a direction substantially perpendicular to the axis of the wire electrode 1 to form a machining gap, and a machining liquid such as water is supplied to this gap and a machining voltage pulse is applied. The cutting process is performed by generating a pulse discharge and moving the workpiece 2 and the wire electrode 1 relative to each other while repeating this discharge.

In addition, a wear-resistant, usually cylindrical current-carrying pin 8 made of cemented carbide or the like is used to apply a voltage pulse by contacting the wire electrode 1.
A+8b is attached.

5 is a Loe power source, which is provided with a high current peak value pulse generation circuit 5a and a low current peak value pulse generation circuit 5b, and two types of pulses are generated and connected to the wire electrode 1 and the workpiece via the energizing pins 8g and 8b. It is applied between 2 and 2. Figure 2 shows the relationship between the pulse discharge current value Ip and the machining time. When the discharge is completed, the peak value of the discharge current is large. The waveform q is a machining pulse with a number N of pulses, and the waveform q has a small energy and the peak of the discharge current. The value is also a processing pulse with a small number of pulses n. Further, 4 is a pulse generation device, 5 is a pulse generation condition storage device, and 6 is a pulse generation condition input device. A setting input and a gap signal are applied to the pulse generation condition input device 6, and some of the pulse generation conditions are stored in the pulse generation condition storage device 5 or directly applied to the pulse generation device 4 from the input device 6. , the number N of pulse outputs of the high current peak value pulse generating circuit 5a and the number n of pulse outputs of the low current peak value pulse generating circuit 5b are controlled and applied to the machining gap.

Thus, depending on rough machining, medium machining, and finishing machining, the respective n and N
The machining conditions are as follows: rough machining n≦N, medium machining nnN, finishing machining n >> N. Optimal electrical control can be obtained to perform wire-cut electric discharge machining throughout finishing machining.

1 As an experimental example, 5KD-11 steel is used as workpiece 2,
Apply the same voltage to a Bs wire electrode 1 with a diameter of 0.25 mm with a voltage pulse width TOn & 5 μsec and τoff 40 μsec. Friend as follows.

n N Machining p1 Machining p2 t Rough machining 10-100 4ON4
00 500A 500A2, Medium processing 4to400 4ON400 250A 550A5 Finishing 10UF%-10001to100150A 25
0A (τOn1.6μaecJ As a result, the roughness of the surface during rough machining is 15~18μRmQX
The machining speed is changed to 2.5~2.7 nwrv'nli n, and the surface roughness is 12~14μRmlx in medium machining.
The machining speed is 14 to 18 surfaces min.
With Qx〃o machining speed [15 to 0.7 xTIITL/11
1i n is obtained.

In this invention, two types of pulses with different current values Ip, high current peak value and low current peak value, are used to supply one machining gap, and the number of pulses with low Ip is The 7JO machining speed can be increased by setting the machining conditions in the following relationship: n≦N for rough machining, n≧N for medium machining, and n >> N for finishing machining, assuming the high pulse number of n and Ip as N. You can get a good finished surface as well as raise the surface. Further, by detecting the state of the machining gap and controlling the number N of high current pulses depending on the frequency of short circuits, disconnection can be prevented. Furthermore, the low current peak value can also be used as a separate discharge for gap detection.

[Brief explanation of drawings]

FIG. 1 is an electrical connection diagram of an embodiment of the device of the present invention, and FIG. 2 is a current waveform diagram of discharged waveforms.

Claims (2)

[Claims] (1) A wire-cut electrical discharge machining device is equipped with a machining power source having a high current peak value pulse generation circuit and a low current peak value pulse generation circuit, and the current value I of the machining power source is
It generates two types of pulse currents with different p and supplies them to the machining gap, where n is the number of pulses with low Ip and N is the number of pulses with high Ip, n≦N for rough machining and n for medium machining. A wire characterized in that machining conditions for current values Ip of the high current peak value pulse generation circuit and the low current peak value pulse generation circuit of the processing power source are set in a relationship such that ≧N, and n≫N in the case of finishing processing. Cut electrical discharge machining equipment. (2) The wire-cut electric discharge machining apparatus according to claim 1, wherein the state of the machining gap is detected and the number of N is controlled depending on the frequency of short circuits to prevent wire breakage.