JPS6012166B2 - electrical discharge machine - Google Patents

Description

[Detailed description of the invention] The present invention relates to an electrical discharge machine, particularly to a speed control device thereof.

A wire electrical discharge machine moves a machining electrode (wire) or a workpiece (workpiece) along a desired shape, and applies a high voltage between the wire and the workpiece to generate an electrical discharge between them, causing damage to the area due to electrical discharge destruction. It can be processed into a desired shape, and has excellent performance with no noise during processing.

A well-known electrode feeding method for electrical discharge machines is the differential voltage method, which provides feeding at a speed proportional to the voltage difference between the discharge gap voltage between the workpiece and the machining electrode and a predetermined reference voltage. However, since the gain between the differential voltage and the feed rate is set constant and at a relatively high value, there is a drawback that the feed tends to pulsate. Another possible method of feeding is to provide a feed at a speed proportional to the discharge gap voltage itself between the workpiece and the machining electrode, but if the material and thickness of the workpiece change, It has been difficult to adjust the relationship between gap voltage and feed rate so as to obtain the optimum relationship between gap voltage and feed rate. In other words, when the optimal gap voltage and feed rate at that gap voltage are known for a certain material and plate thickness, the gap voltage and feed proportional to this are determined in the circuit so that the gap voltage and feed rate can be obtained. Setting a proportional relationship with speed does not mean that it will achieve the optimum gap voltage and feed rate for a different material or thickness. For example, if the feed rate for the same gap voltage is the optimum feed. If the feed rate is set higher than the optimum feed rate, the feed rate will be excessive and the discharge gap will become abnormally narrow, resulting in unstable machining. The present invention is directed to the latter of the above-mentioned feeding methods.
Based on a method that provides feed at a speed proportional to the discharge gap voltage - the aim is to ensure that the relationship between the feed rate and the discharge gap voltage can take an optimal value even if the material of the workpiece changes. It is said that This purpose is achieved by the present invention, which includes a pulse train generation means for converting the voltage between the workpiece and the machining end into a pulse train, and a dividing means for dividing the pulse train into segments based on command numerical data. This is achieved by using the pulse train obtained as the pulse for driving the relative feed of the machining electrode or the workpiece. The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. WP is an electrode, WK is a workpiece, tMT is a motor that stirs the workpiece, for example, a pulse motor, AMP is an amplifier, and VC is a frequency proportional to the voltage. A variable oscillator that generates pulses of F
RS is a register that stores speed data commanded by an input means (not shown), such as a command tape, and DIV is a frequency divider that divides the pulse train generated from the variable oscillator according to the contents of register FRO, and drives the pulse motor MT with the output pulse. It is a vessel. This frequency divider OW is a well-known digital differential analyzer (DigitalDif project) as shown in FIG.
ntialA female lyze). In other words, the cylinder divider DIV is the accumulation rare ACC and the register FR.
The contents of G and the contents of the accumulator ACC are pulsed by P.
, and an adder ADD which adds the result every time , and stores the result in an accumulator.
Therefore, the frequency of pulse P, is fv, the contents of register FRO is F, and the capacity of the accurator is 2n (n is the number of bits).
Then, the accumulator ACC outputs a pulse train P2 with a frequency fc given by the following equation. fC=ftempleF
(1) The optimum voltage and machining speed between the wire and the workpiece are known from experience, depending on the material of the workpiece.

Now, the above voltage for a certain material is VM, and the processing speed is FM.
, when the output frequency of the variable oscillator VC at the time of generation of the voltage VM is Fv, find the content F of the register FRG such that this machining speed FM can be obtained.・．F: Voice G2n (2) This (1}
Substituting into the formula, fC=Poetry/fV (3) However, if the value F given by the formula is inputted into the register FRG from the command tape, machining can be performed at the optimal machining speed.

In addition, if the material of the workpiece is not uniform at all and the voltage changes, the output frequency fv of the variable oscillator Vc will change according to the voltage (3), so the output of the frequency divider DIV By changing the frequency fc, processing can be performed at a speed that corresponds to changes in material quality.

Furthermore, although the material in one workpiece is not uniform at all, it is almost uniform, and fv will not change significantly, so fc will not change significantly, making it possible to perform electrical discharge machining with high precision. It can be carried out. Furthermore, for a workpiece made of 8U material, the machining speed can be controlled by similarly determining the speed data F and inputting it from the command tape.
This shows the machining voltage vs. division output frequency (V vs. fc) characteristics when the content F of O is changed.For workpieces that are easy to cut, F increases and the characteristics shift upward. .

As described above, according to the present invention, "the speed data is commanded according to the material or thickness of the workpiece, and the speed is variable according to the voltage between the electrodes, so the precision is optimal for the material of the workpiece. In addition, the numerical data punched on the command tape is calculated and given by the program at the time of program creation, so that the operator can check the material, plate thickness, etc. of the workpiece one by one at the electrical discharge machining site. There is no need to take into consideration the adjustment and setting of circuit elements each time, and the operation of the electrical discharge machine is extremely simple.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the present invention, Fig. 2 shows an example of a frequency divider, and Fig. 3 shows an example of a frequency divider.
The figure is a diagram showing the voltage between poles versus output frequency characteristic. In the figure, WP is an electrode, DIV is a frequency divider, FRG is a speed data storage register, and VC is a variable oscillator. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A feed motor MT that controls the relative movement between the electrode WP, the workpiece WK disposed opposite to the electrode WP, and the electrode, and a voltage between the electrodes WP and the workpiece WK. and speed control means for responsively controlling the speed of the feed motor MT. a register FRG in which a designated speed control value is set; and a frequency divider DIV that divides the output pulse train of the pulse oscillator VC by the designated speed control value set in the register FRG, and an output of the frequency divider DIV. An electric discharge machine characterized in that a pulse train is used as a pulse train for driving the feed motor MT.