An electrospark machining device for thick workpieces and a frequency conversion feeding method thereof

Abstract

The present invention discloses an EDM device for thick workpieces, comprising: a discharge module; a discharge gap processing module, the discharge gap processing module samples the discharge gap voltage during EDM wire cutting; a dead zone compensation voltage generation module; a subtractor module; a variable frequency feed processing module; a host computer processing module; and a workbench drive pulse module. The method for feeding thick workpieces during EDM wire cutting of the present invention has the following advantages: by detecting the discharge state of thick workpieces, generating the discharge gap voltage, and performing subtractor operation with the dead zone compensation voltage, a real variable frequency feed voltage is generated, and a variable frequency feed signal is generated, thereby overcoming the random interference of multiple external uncertain factors and the dead zone voltage of the circuit components themselves, thereby processing products with excellent performance.

Description

Technical Field

[0001] The invention relates to an electric spark machining device, more specifically, to an electric spark machining device for thick workpieces. Background Art

[0002] As we all know, wire EDM is a kind of electrical machining, that is, it uses the principle of discharge to erode conductive metals. Generally, a reciprocating molybdenum electrode wire (which moves up and down in the workpiece) is used as the cathode, and the metal material is used as the anode (workpiece) to form two poles. With the aid of a medium (cutting fluid), voltage is applied to the two poles. As the distance between the two poles continues to approach, a breakdown discharge is triggered to erode the conductive anode metal material. Maintain the distance between the two poles, move the electrode or metal material at a certain tracking feed speed, and neither short circuit nor open circuit can be achieved, so as to meet the requirements of position size, shape, surface quality, processing speed, molybdenum wire loss, etc. During the EDM process, the distance between the two poles is generally expressed by the voltage between the two poles, which is generally called the discharge gap voltage. After sampling, this discharge gap voltage is output to the frequency conversion circuit to generate a feed signal to drive the worktable to move, thereby discharging and eroding the workpiece.

[0003] like Figure 1 As shown in the figure, the discharge state of wire EDM can be roughly divided into three types, namely open circuit no-load, spark discharge (unstable discharge is also classified here) and short circuit. The ideal state is no open circuit no-load and short circuit, only normal spark discharge. Figure 1 It can be seen that the voltage amplitude values ​​in these three states are different.

[0004] like Figure 2 The figure shows the existing discharge gap voltage peak detection circuit. Specifically, the spark maintenance voltage and short-circuit voltage lower than its voltage regulation value are blocked and filtered out by the voltage regulator W1. Only the no-load peak-to-peak voltage greater than the maintenance voltage can be charged and filtered to the capacitor C1 through the diode D1. The voltage regulator W2 eliminates the no-load voltage higher than its voltage regulation value. The filtered voltage is divided by RW1 and then outputs a voltage signal representing the peak-to-peak value.

[0005] However, as the height of the workpiece increases, due to the mechanical structure and working principle, the jitter of the molybdenum wire moving up and down increases; it becomes increasingly difficult for the cutting fluid to enter the workpiece, especially when the molybdenum wire moves in the opposite direction, that is, when the molybdenum wire moves from bottom to top, it is even more difficult for the cutting fluid to enter the workpiece; at this time, the molybdenum wire and the workpiece are often in a micro-short circuit state, and the reflected gap voltage is very small, sometimes even less than 1V. Due to the inherent reasons of the electronic components, the dead zone compensation voltage of the general variable frequency feed circuit is often as high as 1V, so the variable frequency feed module cannot generate a feed signal, resulting in failure of processing. Summary of the invention

[0006] Based on this, it is necessary to provide an electrospark machining device for thick workpieces in order to solve the above technical problems.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] An electrospark machining device for a thick workpiece, characterized in that the electrospark machining device for a thick workpiece comprises:

[0009] a discharge module, wherein the discharge module performs discharge according to a discharge parameter;

[0010] a discharge gap processing module, wherein the discharge gap processing module samples the discharge gap voltage during wire-cutting electrospark machining, and performs proportional processing on the sampled discharge gap voltage, so as to characterize the magnitude of the discharge gap voltage with a voltage signal;

[0011] a dead zone compensation voltage generating module, wherein the dead zone compensation voltage generating module is used to generate a dead zone compensation voltage;

[0012] a subtractor module, the subtractor module receiving the discharge gap voltage sampled by the discharge gap processing module and the dead zone compensation voltage from the dead zone compensation voltage generating module, and used for generating an accurate variable frequency feed voltage after removing the dead zone compensation voltage;

[0013] a variable frequency feed processing module, the variable frequency feed processing module receives the accurate variable frequency feed voltage output from the subtractor module and generates an accurate variable frequency feed signal;

[0014] A host computer processing module, the host computer processing module receives the accurate variable frequency feeding signal output from the variable frequency feeding processing module and generates an accurate feeding signal;

[0015] A workbench driving pulse module receives accurate feed signals from the host computer processing module, and after power amplification processing, drives the workbench to move and perform discharge machining.

[0016] As a preferred embodiment of the present invention, the dead zone compensation voltage is a negative voltage.

[0017] As a preferred embodiment of the present invention, the subtractor module includes a subtractor, the discharge gap voltage sampled by the discharge gap processing module is input to the non-inverting input terminal of the subtractor, and the dead zone compensation voltage is input to the inverting input terminal of the subtractor.

[0018] As a preferred embodiment of the present invention, the variable frequency feed processing module includes an A / D conversion chip, and the A / D conversion chip is 4066.

[0019] A method for variable frequency feeding using the aforementioned electrospark machining device comprises the steps of:

[0020] Step S1, the discharge module performs discharge;

[0021] Step S2, the discharge gap processing module samples the discharge gap voltage during wire-cut electric discharge machining, and performs proportional processing on the sampled discharge gap voltage;

[0022] Step S3, the dead zone compensation voltage generation module outputs the dead zone compensation voltage;

[0023] Step S4, the subtractor module subtracts the dead zone compensation voltage from the discharge gap voltage sampled by the discharge gap processing module to generate an accurate variable frequency feed voltage after removing the dead zone compensation voltage;

[0024] Step S5, the variable frequency feed processing module receives the accurate variable frequency feed voltage output from the subtractor module, and generates an accurate variable frequency feed signal;

[0025] Step S6, the host computer processing module receives the accurate variable frequency feeding signal output from the variable frequency feeding processing module, and generates an accurate feeding signal;

[0026] Step S7: The workbench drive pulse module receives the accurate feed signal from the host computer processing module, drives the workbench to move, and performs electrical discharge machining.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The method for feeding thick workpieces during wire-cutting of electric sparks of the present invention has the following advantages: by detecting the discharge state of the thick workpiece, generating a discharge gap voltage, and performing a subtractor operation with the dead zone compensation voltage, a real variable frequency feed voltage is generated, and a variable frequency feed signal is generated, thereby overcoming the random interference of multiple uncertain factors in the outside world, and thus processing a product with excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the scheme of the present invention, a brief introduction is given below to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 It is a schematic diagram of the discharge state of wire-cutting electric discharge;

[0031] Figure 2 is a schematic diagram of an existing discharge gap voltage peak detection circuit,

[0032] Figure 3 It is a schematic diagram of module connection of the electric spark machining device for thick workpieces of the present invention;

[0033] Figure 4 is a circuit diagram of a discharge module of the present invention;

[0034] Figure 5 A circuit diagram of a dead zone compensation voltage generating module of the present invention;

[0035] Figure 6 is a circuit diagram of a subtractor module of the present invention;

[0036] Figure 7 A circuit diagram of a variable frequency feeding processing module of the present invention;

[0037] Figure 8 It is a combined circuit diagram of a dead zone compensation voltage generation module, a subtractor module and a variable frequency feed processing module of the present invention;

[0038] Fig. 9 It is a frequency-voltage output curve of the discharge gap voltage sampled by the discharge gap processing module of the present invention and the variable frequency feed signal output by the variable frequency feed processing module. DETAILED DESCRIPTION

[0039] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0040] like Figure 3 As shown, the electrospark machining device for thick workpieces comprises:

[0041] A discharge module 1, wherein the discharge module 1 discharges according to a discharge parameter;

[0042] a discharge gap processing module 3, which samples the discharge gap voltage during wire-cutting electrospark machining and performs proportional processing on the sampled discharge gap voltage, so as to characterize the magnitude of the discharge gap voltage with a voltage signal;

[0043] a dead zone compensation voltage generating module 5, wherein the dead zone compensation voltage generating module 5 is used to generate a dead zone compensation voltage;

[0044] A subtractor module 4, the subtractor module 4 is used to generate an accurate variable frequency feed voltage after removing the dead zone compensation voltage;

[0045] a variable frequency feed processing module 6, which receives the accurate variable frequency feed voltage outputted from the subtractor module 4 and generates an accurate variable frequency feed signal;

[0046] A host computer processing module 7, the host computer processing module 7 receives the accurate variable frequency feeding signal output from the variable frequency feeding processing module 6, and generates an accurate feeding signal;

[0047] A workbench driving pulse module 8 receives an accurate feed signal from the host computer processing module 7, and after power amplification processing, drives the workbench to move and perform discharge machining.

[0048] like Figure 4 As shown, it is a circuit diagram of the discharge module 1.

[0049] The discharge module 1 is composed of a pair of complementary transistors, namely, transistor T1-1 and transistor T1-2 to form a push-pull circuit, which generates a strong electric driving current and a fast wire discharge circuit, completes the rapid opening and closing of the field effect transistor QV1, and thus generates a discharge pulse (breakdown dielectric discharge) and a rest pulse (deionization, restoration of dielectric insulation, preparation for the next discharge) between the workpiece 9 and the molybdenum wire 2.

[0050] Specifically, in the discharge module 1, BSV1 is a pre-amplification shaping circuit, which performs impedance matching, shaping and amplification on the signal from the host computer; a push-pull circuit is composed of a pair of complementary transistors, namely transistor T1-1 and transistor T1-2; in the positive level stage of the signal, transistor T1-1 is turned on, and the D12V power supply quickly charges the field effect transistor QV1 through the diode DV11 and the resistor RV12; in the negative level (0 level) stage of the signal, transistor T1-1 is cut off, transistor TV1-2 is turned on, and the field effect transistor QV1 quickly discharges the field effect transistor QV1 through the resistor RV12; the resistor RV1 is a current limiting resistor, and the diode DV12 is a reverse peak elimination diode.

[0051] like Figure 5 As shown, the dead zone compensation voltage generating module 5 includes a voltage of -9V, and generates a 1.4V regulated voltage value through a voltage stabilizing circuit composed of a resistor R54 and a voltage stabilizing tube T8; a voltage VG is generated through a voltage divider through a resistor R54-1, a potentiometer RW, and a resistor R55 as a dead zone compensation voltage; by adjusting the potentiometer RW, the size of the voltage dead zone compensation voltage VG can be changed.

[0052] like Figure 6As shown, it is the circuit diagram of the subtractor module 4. Since R47=R48=R49=R50, the output voltage VG1 of the subtractor U10 is Vin-VG. Since VG is a negative value, subtracting a negative value is equal to adding the absolute value of this value, that is, the actual value of VG1 is increased, and the increased part offsets the dead zone voltage of the components.

[0053] like Figure 7 The circuit diagram of the variable frequency feed processing module 6 is shown in FIG. U9 (4066) is an A / D conversion chip, which applies the input analog signal voltage VG1 to the 9th pin of the chip, converts it into a waveform of a certain frequency and drives the transistor T7 (8055) to output through the 4th pin; the capacitor C20 between the 6th and 7th pins and the resistor R44 between the 11th pin and the ground determine the frequency.

[0054] Due to the manufacturing process, the 4066 chip has a dead zone voltage. Only when the input analog voltage is greater than this voltage, the 4th pin of the 4066 chip will have a frequency waveform output. This dead zone voltage varies with different products and batches.

[0055] like Figure 8 As shown, it is a combined circuit diagram of a dead zone compensation voltage generation module, a subtractor module and a variable frequency feed processing module, showing how an accurate variable frequency feed signal is obtained.

[0056] Specifically, the subtractor module 4 subtracts the dead zone compensation voltage generated by the dead zone compensation voltage module from the discharge gap voltage sampled by the discharge gap processing module 3, and sends it to the variable frequency feed processing module 6 to generate a frequency waveform as a feed signal to drive the interpolation movement of the machine tool worktable motor to perform discharge machining.

[0057] like Fig. 9 As shown, Line 1 is the frequency-voltage output curve without dead-zone voltage compensation. It can be clearly seen that the frequency waveform is output only when the voltage is greater than VG1.

[0058] Line 2 is a frequency-voltage output curve with dead zone voltage compensation. It can be clearly seen that as long as there is voltage, there will be frequency waveform output. When processing high workpieces, when the sampling voltage is lower than VG1, variable frequency feeding can be performed.

[0059] The following method for frequency conversion feeding of the electrospark machining device in cutting and machining a thick workpiece comprises the following steps:

[0060] Step S1, the discharge module 1 performs discharge;

[0061] Step S2, the discharge gap processing module 3 samples the discharge gap voltage during wire-cut electric discharge machining, and performs proportional processing on the sampled discharge gap voltage;

[0062] Step S3, the dead zone compensation voltage generating module 5 outputs a dead zone compensation voltage, and the dead zone compensation voltage is usually a negative value;

[0063] Step S4, the subtractor module 4 generates an accurate variable frequency feed voltage after removing the dead zone compensation voltage. Specifically, the subtractor module 4 subtracts the dead zone compensation voltage from the discharge gap voltage sampled by the discharge gap processing module 3, which results in an increase in voltage, eliminating the dead zone of the variable frequency feed circuit, and ensuring that the variable frequency feed module can also generate a feed pulse when the discharge gap voltage is small when processing a thick workpiece;

[0064] Step S5, the variable frequency feed processing module 6 receives the accurate variable frequency feed voltage output from the subtractor module 4, and generates an accurate variable frequency feed signal;

[0065] Step S6, the host computer processing module 7 receives the accurate variable frequency feeding signal output from the variable frequency feeding processing module 6, and generates an accurate feeding signal;

[0066] Step S7, the workbench driving pulse module 8 receives the accurate feed signal from the host computer processing module 7, drives the workbench to move, and performs electrical discharge machining.

[0067] The method for feeding thick workpieces during wire-cutting of electric sparks of the present invention has the following advantages: by detecting the discharge state of the thick workpiece, generating a discharge gap voltage, and performing a subtractor operation with the dead zone compensation voltage, a real variable frequency feed voltage is generated, and a variable frequency feed signal is generated, thereby overcoming the random interference of multiple uncertain factors in the outside world, and thus processing a product with excellent performance.

[0068] Without limitation to this, any changes or substitutions that are not conceived through creative work should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined in the claims.

Claims

1. An electrospark machining device for thick workpieces, It is characterized in that The electrospark machining device for thick workpieces comprises: A discharge module (1), wherein the discharge module (1) performs discharge according to a discharge parameter; a discharge gap processing module (3), wherein the discharge gap processing module (3) samples the discharge gap voltage during wire-cut electric discharge machining, and performs proportional processing on the sampled discharge gap voltage, so as to characterize the magnitude of the discharge gap voltage with a voltage signal; A dead zone compensation voltage generating module (5), wherein the dead zone compensation voltage generating module (5) is used to generate a dead zone compensation voltage (VG); a subtractor module (4), the subtractor module (4) receiving the discharge gap voltage sampled by the discharge gap processing module (3) and the dead zone compensation voltage from the dead zone compensation voltage generating module (5), and used to generate an accurate variable frequency feed voltage after removing the dead zone compensation voltage; a variable frequency feed processing module (6), the variable frequency feed processing module (6) receiving the accurate variable frequency feed voltage outputted by the subtractor module (4) and generating an accurate variable frequency feed signal; a host computer processing module (7), wherein the host computer processing module (7) receives the accurate variable frequency feeding signal outputted by the variable frequency feeding processing module (6) and generates an accurate feeding signal; A workbench driving pulse module (8), the workbench driving pulse module (8) receives the accurate feed signal from the host computer processing module (7), and after power amplification processing, drives the workbench to move and perform discharge machining.

2. The electrospark machining device for thick workpieces according to claim 1, It is characterized in that The dead zone compensation voltage (VG) is a negative voltage.

3. The electrospark machining device for thick workpieces according to claim 1, It is characterized in that The subtractor module (4) comprises a subtractor (U10), the discharge gap voltage sampled by the discharge gap processing module (3) is input to the non-inverting input terminal of the subtractor (U10), and the dead zone compensation voltage (VG) is input to the inverting input terminal of the subtractor (U10).

4. The electrospark machining device for thick workpieces according to claim 1, It is characterized in that The variable frequency feed processing module (6) comprises an A / D conversion chip (U9), and the A / D conversion chip (U9) is 4066.

5. A method for variable frequency feeding using the electrospark machining device as claimed in claim 1, comprising the steps of: Step S1, the discharge module (1) performs discharge; Step S2, the discharge gap processing module (3) samples the discharge gap voltage during wire-cut electric discharge machining, and performs proportional processing on the sampled discharge gap voltage; Step S3, the dead zone compensation voltage generating module (5) outputs the dead zone compensation voltage; Step S4: The subtractor module (4) subtracts the dead zone compensation voltage from the discharge gap voltage sampled by the discharge gap processing module (3) to generate an accurate variable-frequency feed voltage after removing the dead zone compensation voltage; Step S5: The variable-frequency feed processing module (6) receives the accurate variable-frequency feed voltage output from the subtractor module (4) and generates an accurate variable-frequency feed signal; Step S6: The host computer processing module (7) receives the accurate variable-frequency feed signal output from the variable-frequency feed processing module (6) and generates an accurate feed signal; Step S7: The workbench drive pulse module (8) receives the accurate feed signal from the host computer processing module (7), drives the workbench to move, and performs electrical discharge machining.

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