SU865575A1 - Method and apparatus for electro-erosion working - Google Patents

Description

(54) METHOD OF ELECTRIC PROCESSING AND DEVICE FOR ITS IMPLEMENTATION

The invention relates to the electrosurgery treatment of metals by spark discharge and can be used, for example, for electrospark grinding. The known method of erosion treatment by a series of dependent spark discharges by applying an increasing voltage to the electrode tool at a speed not exceeding the speed of restoration of the properties of the gap after passing the spark discharge and increasing the growth rate after reaching the threshold voltage tl on the tool electrode. . The disadvantage of this method is the impossibility of ensuring the optimal processing mode in terms of its speed and quality, corresponding to the change in the properties of the cavity in the process. This is due to the inability to adjust the threshold voltage during processing depending on the Specific properties of the gap. To achieve high processing speed, the threshold voltage should be reduced, while to restore the dielectric properties of the gap and prevent the arc, which reduces the quality of processing, the threshold voltage should be increased. In the known method, the value of the threshold voltage is chosen before the start of operation of the device and this cannot provide the optimal treatment mode when the gap properties change randomly. A device for carrying out this method is known, comprising an electrode-instrument, a capacitive energy storage device, a voltage increase switching unit, a constant voltage source, and a threshold circuit tl. The drawback of the device is that the threshold scheme in the device is manually adjusted before starting work on a certain, pre-selected threshold voltage, which does not provide an optimal processing mode in terms of speed and quality, caused by the need to adjust the threshold voltage during operation. . The purpose of the invention is to increase the processing speed while maintaining the quality of the treated surface. The goal is achieved by the fact that in the method of erosion processing a series of dependent spark bits

by applying an increasing voltage to the electrode tool with a speed not exceeding the dielectric properties of the gap after passing a spark discharge, and increasing the voltage increasing rate after reaching the threshold voltage on the electric tool, the threshold voltage is automatically inversely proportional to the average in the series value of one of the measured electrical parameters characterizing the dielectric properties of the gap, for example, the voltage instR5 ente-way at the time of discharge. In this case, the regulation of the threshold voltage is made in accordance with the ratio

Vp VnoP-KP,

I70R adjustable threshold voltage; VnoB is the maximum threshold voltage value that is set during the pre-tuning process;

.K is the coefficient determining the range of adjustment of the threshold voltage (set during the pre-setting process);

P - c) In a series of bits, the value of the voltage on the tool electrode at the time of the discharge.

An apparatus for carrying out the method, comprising an electrode-tool capacitive energy storage, a voltage increase rate switching unit, a constant voltage source and a threshold circuit, is equipped with a spark parameter measuring unit, a threshold voltage control setting unit and a threshold voltage regulator, with In this case, the input of the measurement unit of the spark-discharge parameter is connected to the tool electrode, its output and the output of the control-limit setting unit are connected to the corresponding inputs threshold voltage regulator, and the output of the latter is connected to the control input of the threshold circuit.

An understanding of the gap and the deterioration of the dielectric properties of the working fluid in the gap leads to a togl, which causes a spark at low voltages on the tool electrode, which leads to. processing speed. With a further reduction of the gap, an arc arises, which leads to the heating of the working fluid and the surface of the part being burned, which not only reduces the processing speed, but also degrades the quality of the surface being treated. Thus, the voltage on the electrode tool at the time of the occurrence of the discharge can serve as an indicator of the properties of the gap.

To eliminate negative effects, it is necessary to improve the restoration of the dielectric properties of the gap. This is achieved by increasing the threshold voltage value.

As the negative effects disappear, the threshold voltage is lowered to a value at which the processing speed reaches its maximum value.

Thus, the adjustment of the threshold voltage by the average in a series of bits of the voltage of the electrode electrode at the moment of occurrence of the discharge provides an increase in processing speed while maintaining the quality of the surface to be treated.

In addition to the specified adjustment parameter (voltage regulation on the instrument electrode at the moment of discharge), other parameters of the spark discharge, the amplitude of current pulses in the gap, the amplitude of voltage pulses on the electrode instrument, etc., can also serve as control parameters.

The drawing shows a functional diagram of the proposed device for implementing the method.

The method is sacrificed as follows.

An increasing voltage is applied to the tool electrode at a rate not exceeding the rate of recovery of the gap properties after passing the previous discharge. This mode is maintained until the threshold voltage value is reached, after which the voltage rise rate is increased until the occurrence of the spark discharge.

. During processing, porous Han – i automatically adjust depending on the value of one of the measured electrical parameters characterizing the dielectric properties of the gap. Such can be the voltage at the tool-electrode electrode at the time of the discharge, the amplitude of the current pulses in the gap, the amplitude of the voltage pulses at the electrode-tool, etc.

The average in a series of bits of the value of one of these parameters, which is used to regulate the threshold voltage, is determined during processing and the threshold voltage is adjusted in accordance with the ratio

where adjustable threshold

voltage;

Claims (3)

Vfiop is the maximum value of the threshold voltage, set before the start of processing; k is the coefficient that determines the threshold voltage control range (set before starting processing; p is the average value of the spark discharge parameters in a series of bits, which is used to control the horizontal voltage. The choice of the parameter by which the threshold voltage is adjusted voltage, produced on the basis of specific processing conditions, type of equipment and workpiece. The device for implementing the method contains an electrode-tool 1, a capacitive energy storage device 2, a switch unit 3 voltages, constant voltage source 4, and threshold circuit 5. The device is equipped with a spark voltage meter measurement unit and a threshold voltage Jierl generator 8 for adjusting the threshold voltage during voltage threshold processing. Yes, if the threshold voltage is controlled by the voltage on an electric tool, it is an amplitude detector, the output voltage of which (F) is proportional to the average in a series of bits e .niyu on the electrode-tool at the time of occurrence of discharge. The unit 7 for setting the threshold voltage control limits contains two independent dividers with a switchable division factor and two switches with which the Vnop and K values required for this type of parts, previously found from the analysis of the processing speed and quality: the surface in an experimental series of parts. Cores corresponds to the value of the voltage With the voltage for the case of restoring the properties of the gap in the same mode. The oriented value for OPOR is within (0.15-35) V, where Vc is the voltage of source 4 of constant voltage. The threshold voltage regulator 8 is an inverting amplifier with a gain of K. The latter is set before starting processing in block 7 and determines the range of control of the threshold voltage. The output voltage of the regulator, depending on the input value P, takes the values than and causes the desired control effect. The outputs of block 6 and block 7 are connected to the corresponding inputs of threshold voltage regulator 8. The input of block b is connected to the electrode insert 1, and the output of regulator 8 to the control input of the threshold circuit 5. The proposed device works as follows. When a spark discharge occurs at a point, the voltage across the electrotool 1 drops sharply. The moment of occurrence of the discharge is fixed by the threshold circuit 5, which is triggered by a sharp drop in voltage and sets the block 3 switching the rate of voltage rise to a position at which the voltage on the capacitive energy storage 2 and on the electrode tool 1 occurs with a speed not exceeding the recovery rate of the dielectric properties of the gap. When the voltage at the electrode tool 1 and the capacitive storage device 2 reaches a threshold value, the process of restoring the dielectric properties of the gap ends. The threshold circuit 5 triggers and switches the switching unit 3 of the rate of increase in voltage so that a fast charge of the capacitive energy storage 2 of the energy to the maximum voltage starts, at the moment when the voltage on the tool electrode and the distance from the second to the workpiece sufficient, a spark occurs, the threshold circuit 5 is activated, returns to the initial state and sets block 3 to its original position. From this moment a new cycle of operation of the device begins. The average in the series of bits the value of the spark bit parameter, which is controlled by, is measured by block b. The output voltage P from the block b is fed to the input of the regulator 8, the output of which produces a voltage dependent on P and receiving the value of VnoP. which is fed to the input of the threshold circuit 5. The method implemented by the proposed device makes it possible to ensure an optimal mode of speed and quality of erosion treatment. Claim 1. Electro-erosion treatment method by a series of dependent discharges, consisting in supplying an increasing voltage to an electric tool with a speed not exceeding the dielectric properties of the gap, and increasing the voltage increase rate after reaching the threshold voltage corresponding to the electrode voltage. that, in order to increase productivity, the threshold voltage automatically adjusts inversely proportional to the average value of one in a series of bits about from the measured electrical parameters characterizing the dielectric properties of the gaps. 2. Method POP.1, characterized in that the voltage on the tool electrode is measured at the moment of the occurrence of the discharge and the threshold voltage is adjusted in accordance with the ratio Vnop 49 {fx-KP. where Vp (jp-adjustable threshold voltage; pore is the maximum value of the stresses of the horny stress, determined experimentally; K - coefficient determining the range of regulation 74/1 and determined by experienced However, P is a measurable parameter, 3. An apparatus for carrying out the method according to claim 1, including a power tool, a capacitive energy storage unit, a voltage increase rate switching unit, a constant voltage source, and a threshold circuit, characterized in that it is provided with a measurement unit, a spark parameter, a task unit the threshold voltage control and the threshold voltage regulator, while the input of the measurement unit of the parameter of the spark discharge is connected to the tool electrode, its output and the output of the limit setting unit are regulated are connected to respective inputs of the regulator porogoyogo voltage, and the last output - to the control input of the threshold circuit. Sources of information taken into account in the examination 1. US patent 3549851, CL 219-69 1970,