CN1031668A - Spark machined discharge parameter checkout gear and parameter measurement circuit - Google Patents

Abstract

The invention relates to a device for quantitatively detecting time parameters of various gap states in electric discharge machining and a parameter measuring circuit for such a device. The device detects the voltage, current and high-frequency signals of the machining gap to obtain pulses representing no-load, spark discharge, transitional arc, stable arc and short circuit. And the low-pass filter forms the time ratio parameters of the above gap states in the ti time. This circuit has the characteristics of simple structure, low cost, easy debugging, and easy computer processing of output parameters.

Description

The invention relates to a device for quantitatively detecting time parameters of various gap states in electric discharge machining and a parameter measuring circuit for such a device.

EDM technology is an effective technology in contemporary mold manufacturing. Due to the stable arc discharge during the machining process, the surface of the workpiece and tool is burned, resulting in the scrapping of expensive molds. Therefore, in recent years, technologies such as the identification of the machining gap state in EDM, parameter measurement, and adaptive optimal control of the machining process have received extensive attention from the EDM industry in various countries. Existing devices similar to the present invention, such as US Pat. No. 4,249,059, use the method of measuring the voltage level of the gap to identify the state of the gap. It utilizes the law that the processing discharge voltage is a constant of about 25 volts, the no-load voltage is close to the DC power supply voltage in the high-frequency power supply of the EDM machine tool, and the short-circuit voltage is close to zero volts. Two voltage comparison thresholds are preset, one of which is lower The no-load voltage is higher than the discharge voltage, and the other is higher than the short-circuit voltage but lower than the discharge voltage. When the processing gap voltage is higher than the two comparison voltages, it means that the gap is in a no-load state; when the processing gap voltage value is less than the first voltage threshold but greater than the second threshold, the gap is considered to be in a discharge state; when the gap voltage value is low When the above two thresholds are met, the gap is considered to be short-circuited. The main disadvantages of this device are: 1. It can only identify the three states of "no load", "discharge" and "short circuit" and cannot identify the states of "stable arc" that endangers the processing quality; 2. Due to the high The electric energy supplied by the frequency power supply to the processing gap is pulse by pulse. During the pulse interval time to, the processing gap voltage disappears. The device also counts this state as "short circuit", so it cannot distinguish between "short circuit" and the above-mentioned inter-pulse time. "to"; 3. The device only qualitatively displays the identified three states. Three light-emitting diodes are used to display the three gap states, and the brightness of the light-emitting diodes is used to indicate the time ratio of each gap state. size. European patent EP 9928 and U.S. patent US4338504 adopt the method of comprehensive detection of processing gap voltage and high-frequency signal. The method is the same as US 4249059. The method of high-frequency signal detection is to send the processing gap voltage to a high-pass filter to separate the high-frequency component in the gap voltage signal and then form a pulse after amplification, detection and filtering. When the gap discharge If the pulse exists at this time, it means that the gap discharge is generated from the high-frequency oscillation component, which is considered to be "spark" discharge, and when the pulse disappears, it is considered to be "arc" discharge. Although this patent can identify "spark" and "arc", it still has the shortcoming of not being able to separate the short circuit from the interpulse time of the high-frequency power supply. U.S. Patent No. 4,338,504 just uses the "arc" signal pulse identified by it to control an audio generator, and when the "arc" pulse identified by it is stronger, the loudspeaker sounds an alarm. Only the European patent EP 9928 involves the quantitative measurement of the gap state time parameter in machining. It can only measure the parameter "arc discharge time" as a percentage of "total gap discharge time". This measurement circuit generates a 5MH _Z clock pulse, which is counted by two counters, one of which is controlled by the detected "arc" state pulse, and only counts when the arc is discharged; the other is detected by the representative gap discharge The pulse control of the state, as long as it counts as soon as a discharge occurs in the gap. When the above-mentioned second counter counts a preset value, the count value of the above-mentioned first counter is converted to D/A and then displayed and output as an analog quantity. The disadvantages of this measurement method are: 1. The counter works in the high-frequency interference environment generated by strong electric spark discharge, which will affect the reliability of the measurement line; 2. The structure of the measurement line is more complicated; 3. The measurement parameters are only "arc " or "spark" discharge accounts for the percentage of the total discharge time. Since the time percentage is not greatly affected by the change of the machining gap size of the machine tool, it cannot include the machining gap size, that is, the information of the machine tool servo feed, so this parameter cannot be used directly. It is used to evaluate and control the servo feed of the machine tool; 4. Since the EDM process is a very complicated process, only measuring one or two parameters is far from enough to predict the "stable arc discharge" in the process and to predict the machining process. The need for adaptive optimal control of the process.

The task of the present invention is to propose a parameter measurement line with simpler structure and lower cost, the measured parameters include servo feed information between tool and workpiece, and its dynamic characteristics are easy to be processed by computer. This detection parameter is more complete, and it can detect the precursor of "stable arc discharge" and "transitional unstable arc discharge" parameters. It is a device for quantitative detection of various gap state time parameters in EDM. This device can be used as a tool in EDM A detection component in the microcomputer adaptive control system can also be used for manual monitoring of the processing process.

Based on a large number of experimental studies on the characteristics and frequency spectrum analysis of high-frequency signals generated in EDM, the present invention adopts a new method for comprehensive detection of the processing gap voltage, current and the intensity of high-frequency random oscillation signals, and designs a new method for Lines for identification of processing gap status. The purpose of detecting the gap voltage and current is to accurately identify the three gap states of "no load", "discharge" and "short circuit", which can overcome the inability to distinguish short circuit and pulse-to-pulse states of high-frequency power output pulses in the prior art shortcoming. The basic idea is: when there is voltage at both ends of the gap and no current flows in the gap, it means that the gap is open; when there is both voltage and current in the gap, it means that the gap is in a discharge state; when there is only current and no voltage in the gap It means that the gap is short-circuited. When the gap is in the discharge state, three states of "spark", "transition unstable arc" and "stable arc" can be identified by measuring the strength of the high-frequency random oscillation signal. The method is: if the gap discharge produces a strong high-frequency random When the signal oscillates, it means "spark" discharge; when the high-frequency signal weakens, it means "transitional unstable arc" discharge; when the high-frequency signal disappears, it means "stable arc" discharge. Since the present invention is mainly used in the occasion of computer dynamic real-time control of the machining process, it is not only required that the measured parameters include the servo feed information of the machine tool, but also have good dynamic characteristics, which should facilitate the establishment of mathematical models and facilitate computer deal with. Through theoretical and experimental research on the control algorithm and mathematical model of the processing process, the entire test system is required to be a first-order system. Through circuit experiments and theoretical analysis, a novel circuit for analog measurement of the time parameters of each gap state has been developed. This circuit can measure the "no-load ", "spark discharge", "transitional unstable arc discharge", "stable arc discharge", "short circuit" and other five basic gap states accounted for the analog quantity of the statistical time percentage parameter.

The content of the present invention will be described below with reference to FIG. 1 . The invention mainly includes an encoder, a decoder, a parameter measuring device and an output interface. The parameter measuring device is the specific application of the parameter measuring circuit in this device. While explaining the parameter measuring device, the structure and measuring method of the circuit are explained. The encoder consists of a voltage detection circuit 1, a current detection circuit 2 and a high frequency detection circuit 3. The input end of the voltage detection circuit is connected to both ends of the processing gap 11, and the output end outputs Tu signal. The function of this circuit is to convert the gap voltage into a pulse Tu of "0" or "1". Voltage (such as 11 volts), the output pulse Tu is a logic "1", otherwise it is a logic "0". The input end of the current detection circuit is connected to both ends of a main circuit current limiting resistor 12 in the high frequency pulse power supply of the EDM machine tool to measure the current voltage drop on the resistor, and the output end of the circuit outputs a Ti signal. The function of the current detection circuit 2 is to convert the voltage drop of the current limiting resistor 12 into a pulse Ti of "0" or "1". When the voltage drop of the current limiting resistor 12 is higher than half of its own peak value, the output pulse Ti is logic "1", logic "0" otherwise. The input terminal of the high-frequency detection circuit 3 is connected to the processing gap 11, and the output terminal outputs two pulse signals of TH and TL. It is logic "1"; when the above-mentioned high-frequency signal weakens, TH is logic "0" and TL is logic "1"; when the above-mentioned high-frequency signal disappears, both TH and TL are logic "0". The function of the high-frequency detection circuit 3 is to detect the strength of the high-frequency signal component on the discharge voltage to distinguish whether it is "spark discharge" or "transitional unstable arc" or "stable arc discharge". In order to realize the above functions of the encoder, the voltage detection circuit 1 can be composed of a voltage divider circuit and a gate circuit or a voltage divider circuit and a voltage comparator; Neither end can be directly connected to the common terminal of the voltage detection line 1 and the high frequency detection line 3, in order to make the output signal Ti of the current detection line 2 and the output signal of the voltage detection line 1 and the high frequency detection line 3 have the same zero voltage Therefore, an isolation circuit can be used to isolate the input and output of the current detection circuit 2, so the current detection circuit can be composed of a voltage divider circuit and a high-speed optocoupler; the high-frequency detection circuit can be composed of a high-pass filter, amplifier, demodulator and Composed of two voltage comparators, the processing gap voltage is directly input to the high-pass filter. During processing, the high-pass filter separates the high-frequency components of the discharge voltage. After being amplified by the amplifier, it is detected and filtered by the demodulator, making it a A pulse signal, the amplitude of the pulse signal is proportional to the amplitude of the above-mentioned high-frequency component, this pulse signal is directly transmitted to the above-mentioned two voltage comparators, one of the voltage comparators has a higher comparison voltage, and the voltage comparator Output TH signal, the comparison voltage of another voltage comparator is lower, it outputs TL signal. When a "normal spark discharge" occurs during processing, a strong high-frequency random oscillation signal is generated in the gap 11, so that the amplitude of the pulse signal output by the above-mentioned demodulator is higher than the comparison voltage of the above-mentioned two voltage comparators, and both TH and TL All signals are logic "1"; when "transitional unstable arc discharge" occurs during processing, the above-mentioned high-frequency signal is weakened so that the pulse amplitude output by the demodulator is between the above-mentioned two comparison voltages, TH is logic "0", TL is logic "1"; when a "stable arc discharge" occurs during processing, the above-mentioned high-frequency signal disappears and the pulse amplitude output by the demodulator is lower than the above-mentioned two comparison voltages, TH and TL Both signals are logic "0". The input terminal of the decoder 4 is connected to the output terminal of the encoder, and the Tu, Ti, TH and TL pulses output by the encoder are sent to the decoder 4, and the decoder performs logical decoding on this, and the decoded signal represents "no load" Td of "spark" discharge, Te' of "transition unstable arc", Ta of "stable arc" and TS of "short circuit" and other five pulse signals. The pulse widths of these pulse signals are synchronously equal to the instantaneous time of their corresponding gap states, that is, the dead time td, the spark discharge time te, the transition unstable arc discharge time te′, the stable arc discharge time ta, and the short circuit time ts. See Figure 2 for comparison, the first row in Figure 2 is the waveform of the processing gap voltage Ug. In addition, the decoder 4 also outputs a synchronous pulse signal TΣ, whose pulse width and pulse interval are synchronously equal to the pulse width ti and pulse interval to of the output pulse of the high-frequency pulse power supply of the EDM machine tool. The decoder can be composed of gate circuits that can realize the above functions or a double 2-4 decoder, or a 4-16 decoder, or a BCD-10 line decoder and other general logic devices and gate circuits, which should meet The following logical relationship:

Td＝Tu·Ti

Te＝Tu·Ti·TH·TL

Te'＝Tu·Ti·TH·TL

Ta＝Tu·Ti·TH·TL

Ts＝Tu·Ti

TΣ=Tu+Ti.

If it is necessary to isolate the level between the encoder and the parameter measuring device, the decoder 4 also includes a high-speed optocoupler for isolating the input signal or the output signal respectively, and the input signal enters the decoder after being isolated by the high-speed optocoupler The internal or decoded output signal is isolated by a high-speed optocoupler and then output to the outside.

The parameter measuring circuit is the core of the present invention, and the parameter measuring device is the concrete application of this circuit in this device, and its effect is that the Td, Te, Te ', Ta, Ts pulse signal that the decoder outputs are transformed into td/ Analog voltage for ti, te/ti, te′/ti, ta/ti, ts/ti parameters. The parameter measurement circuit can also be used for other similar devices that only measure one or several parameters in the above parameters. The parameter measuring device is composed of a pulse amplitude modulator 5, an analog switch 6, a low-pass filter 7 and an amplifier 8, and an amplitude stabilizing circuit 10 can also be added on the basis of the above structure. The function of the pulse amplitude modulator 5 is to convert the amplitude of the pulse sent by the decoder. It is required that the circuit output a high level equal to its own power supply voltage under the condition of no load, and the output low level should be zero volts. , so that the output pulse amplitude has higher precision, so it can be composed of CMOS gate circuits or other forms of circuits with similar performance. The switch part of the analog switch 6 is connected between the output terminal of the pulse amplitude modulator 5 and the input terminal of the low-pass filter 7, and the control input terminal J of the analog switch 6 inputs a TΣ signal, so the analog switch is controlled by the TΣ pulse. When TΣ is "1", the switch part of the analog switch is turned on during the ti time of the output pulse of the high-frequency pulse power supply; when TΣ is "0", it is simulated during the to time of the output pulse of the high-frequency pulse power supply The switch part of switch 6 is turned off. The output value of the low-pass filter 7 remains unchanged when the analog switch 6 is turned off, and it may be a first-order low-pass filter. The function of the amplifier 8 is to perform impedance transformation on the output signal of the low-pass filter 7, so that the output value of the low-pass filter 7 is not affected by the load after it is loaded, and the amplifier 8 can be omitted when the output load impedance is very high. When the parameter measuring device does not use the amplitude-stabilizing line 10, the pulse amplitude modulator 5 is powered by a DC regulated power supply, so the power supply input terminal K of the pulse amplitude modulator 5 should be connected to one end of the output of the regulated power supply. The output pulse amplitude of the pulse amplitude modulator 5 can be adjusted by adjusting the output voltage value of the stabilized power supply, so as to calibrate the full scale value of each output signal. When the parameter measuring device was added to the amplitude-stabilizing line 10, the pulse amplitude modulator 5 was powered by the amplitude-stabilizing line 10, and the amplitude-stabilizing line 10 was composed of a single-way pulse amplitude modulator 13, an analog switch 14, a low-pass filter 15, an amplifier 16, an Compressor 17 is composed. The function of the amplitude stabilizing circuit 10 is to use the synchronous pulse TΣ as the value after processing by the pulse amplitude modulator 13, the analog switch 14, the low-pass filter 15 and the amplifier 16, that is, the voltage value between the two points F and H as a reference value to adjust the I The voltage between point F and point H keeps the voltage between point F and point H constant under any processing pulse width ti and pulse-to-pulse to, so that the full-scale calibration value of each output parameter signal is stable, so as to improve the measurement precision. Above-mentioned adjusting function is realized by regulator 17, and F point is its detection input end, and I point is its output end, and H point is its output common end, and L point and G point are its power supply input ends, if The amplifier 16 can be omitted when the detection input impedance of the regulator 17 is high. Adjusting the gain of the amplifier 16, or adjusting the detection ratio of the voltage regulator 17F point, or adjusting the given reference voltage inside the voltage regulator 17 can adjust the output pulse amplitude of the pulse amplitude modulator 5 to calibrate the full scale value of each output signal. The effect of the amplitude stabilizing circuit 10 is: when the pulse amplitude modulator 5 works at a high frequency, especially when ti is less than 1 microsecond, the amplitude of its output is low due to the influence of the response speed, and the amplitude stabilizing circuit can control the pulse The actual pulse amplitude output by the amplitude modulator is stabilized to compensate for the deviation caused by the change of the working frequency. The working principle of the parameter measuring device is: after the gap state pulses Td, Te, Te′, Ta and Ts pass through the amplitude modulator 5 respectively, their amplitudes are precisely controlled, and then each pulse signal passes through the analog switch 6 and the low-pass After the filter 7 and the amplifier 8, the average voltage of each gap state pulse is obtained. Since each analog switch is controlled by the TΣ signal, it is only closed in the pulse width time "ti" of the output pulse of the high-frequency pulse power supply of the electric discharge machine tool. Each low-pass filter can work, and when the above-mentioned pulse is in the inter-pulse time to, each analog switch is turned off, so that the output value of each filter remains unchanged. Therefore, the output voltage of each filter is linearly proportional to the average time percentage parameter of each corresponding gap state within "ti".

Positive logic or negative logic or a combination of positive and negative logic can be used in the present invention.

Output interface 9 is the connection part that the output terminals such as A, B, C, D, E of the parameter measurer of the device of the present invention are connected with external equipment, such as computers or recorders, etc., if the device of the present invention is used as an independent In the case of an instrument for displaying gap state parameters during processing, the output interface 9 should also include a display connected to the output terminal of the parameter measuring device, which is composed of an adjustable current-limiting resistor, a current or voltage meter head, or a general-purpose luminous level indicating component composition.

The main advantages of the present invention are:

1. It can correctly identify five basic gap states such as "no load", "spark discharge", "transitional unstable arc", "stable arc" and "short circuit", which can overcome the shortcomings of the above-mentioned European and American patents.

2. The time percentage parameters of the above five basic gap states in the pulse width period "ti" of the high-frequency power supply output pulse of the machine tool can be set. These parameters contain information on the servo feed between the tool 5 and the workpiece on the machine tool. For example, when the machining gap is too large, the no-load parameter td/ti is too large; when the machining gap is too small, the short circuit parameter ts/ti is too large; when the machining gap is appropriate, if the gap is not polluted by discharge debris, the spark discharge parameter te/ti If the gap is polluted, the transition unstable arc parameter te′/ti and the stable arc parameter ta/ti are too large. After processing these parameters, the servo feed of the machine tool can be directly controlled to directly adjust the size of the machining gap. Therefore, the parameters measured by the present invention are more practical.

3. Since "transitional unstable arc" is a precursor to "stable arc", it is an important information to predict the appearance of "stable arc" to prevent arc burns. Identifying this state and measuring the time parameter means that the EDM detection technology an important progress.

4. The parameters measured by the present invention are perfect, and the number of measured parameters is equal to five times that of the European patent EP 9928, while the circuit structure is greatly simplified, making it reliable and low in cost.

5. The test dynamic characteristic of the present invention is a first-order characteristic, which is easy to be processed by a computer and to establish a mathematical model for the entire processing system.

Fig. 1 is a circuit block diagram of the device of the present invention.

Fig. 2 is a comparison diagram of the machining gap voltage waveform in EDM and the signal waveforms output by the decoder 4 in the block diagram shown in Fig. 1 .

Fig. 3 is a circuit diagram of an embodiment of the device of the present invention.

Application examples of the present invention will be described in detail below. Figure 3 provides an ideal implementation of a fully integrated circuit. The voltage detector 1 is composed of a resistor divider composed of R ₁ and R ₂ , a high-speed voltage comparator Ii, and a comparison voltage adjustment potentiometer R _3. The gap voltage is directly sent to the voltage divider, and the output signal of the voltage divider is sent to The high-speed voltage comparator I ₁ adjusts R ₃ to adjust the threshold voltage of the entire voltage detector 1, which can be set at about 11 volts. The current detector 2 is composed of a resistor divider composed of _R4 and _R5 , a current limiting resistor _R6 and an integrated circuit type ultra-high-speed optocoupler _I2 with a response time of less than 0.5 microseconds; the current signal is sent from the electric discharge machine tool The current-limiting resistor 12 of the main circuit of the high-frequency pulse power supply is obtained by measuring the current voltage drop at both ends, and the signal is sent to the primary of the optocoupler _I2 through the resistor divider, and the secondary output of the optocoupler _I2 is the Ti signal. The threshold voltage of the whole circuit is about 1/2 of the peak voltage drop at both ends of the resistor 12 during processing discharge.

The high-pass filter in the high-frequency detection circuit 3 is an RC differential circuit composed of R ₁ and C ₁ , and the starting frequency is about 30MH _Z ; the amplifier I ₃ is a differential high-frequency broadband amplifier, and its cut-off frequency can be 80MH _Z About, its gain is 40db, I ₃ can use LM 733 and other integrated chips, so the high-pass filter and amplifier I ₃ composite frequency band is 30MH _Z -80MH _Z ; the demodulator consists of C ₂ , C ₃ , D ₁ , D ₂ , The full-wave voltage doubler rectifier composed of D ₃ and D ₄ and the peak filter composed of R ₈ and C ₄ are composed. The time constant of R ₈ C ₄ is about 0.5 microseconds; I ₄ and I ₅ are high-speed voltage comparators , The comparison voltage of I ₄ is adjusted by R ₉ , which can be adjusted to about 1 volt, and the comparison voltage of I ₅ is adjusted by R ₁₀ , which can be adjusted to about 0.3 volts. R ₇ and C ₁ filter out the high-frequency components on the gap voltage, and the high-frequency components are amplified by I ₃ and then passed by C ₂ , C ₃ , D ₁ , D ₂ , D ₃ , D ₄ and C ₄ and R ₈ After the demodulator is formed, a pulse signal is obtained, and the amplitude of the pulse is proportional to the amplitude of the high-frequency component. When the high-frequency component is very strong, the pulse amplitude is higher than the comparison voltage amplitude of _I4 and _I5 value, TH output by I ₄ and _TL output by I ₅ are both logic "1"; when the high-frequency component is weakened, the demodulator output pulse amplitude is lower than the comparison voltage of I ₄ but the level is higher than the comparison of I ₅ Voltage, so that the TH output by _I4 is logic "0", and the T _L output by _I5 is logic "1"; when the high-frequency component disappears, the demodulator output pulse amplitude is very low, close to zero volts, that is Below the comparison voltage of _I4 and _I5 , TH and TL are logic "0".

Fig. 3 provides a scheme that adopts general double 2-4 decoder I ₆ and five inverting gates G ₁ , G ₂ , G ₃ , G ₄ , G ₅ to form decoder 4 .

The amplitude modulator 5 in the parameter measuring instrument is composed of CMOS non-inverting gate circuits G ₆ , G ₇ , G ₈ , G ₉ , and G ₁₀ , and can adopt MC 14050 or CD 4050 integrated chip; the analog switch 6 is composed of CMOS analog gate G ₁₁ , G ₁₂ , G ₁₃ , G ₁₄ , G ₁₅ etc., can use MC 14016 or CD 4016 integrated chip; low-pass filter 7 is R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₁₅ and C ₅ , C ₆ , C ₇ , C ₈ , C ₉ form the five-way RC first-order low-pass filter, its filter time constant depends on the specific use of the device, generally should be greater than 2 milliseconds; amplifier 8 is composed of integrated operational amplifier I _7. A five-way voltage follower composed of I ₈ , I ₉ , I ₁₀ , and I ₁₁ ; the amplitude stabilization line 10 is composed of a CMOS non-inverting gate G ₁₆ , an analog switch G ₁₇ , a low-pass filter R ₂₁ C ₁₀ , and an amplifier I ₁₂ , Potentiometer R ₂₂ and three-terminal regulator I ₁₃ . The time constant of the low-pass filter R ₂₁ C ₁₀ is the same as that of the low-pass filter 7; I ₁₃ is a three-terminal integrated voltage regulator chip that outputs negative voltage, and its voltage stabilization value should be equal to or greater than the full scale of the output parameter of the parameter measurer calibration value. The common terminal of I ₁₃ is connected to point F, the input terminal is connected to point G, the output terminal is connected to point H, the positive pole of the DC power supply of the amplitude-stabilizing line 10 is connected to point I, and the negative pole is connected to point G. The closed-loop gain of the amplifier I ₁₂ can be adjusted by R _22. Adjusting this amplifier gain can adjust the output pulse amplitude of the amplitude modulator to adjust the full-scale value of each parameter of the entire line output. Points A, B, C, D, and E in Fig. 1 and Fig. 3 correspond to output analog voltages of five parameters of td/ti, te/ti, te'/ti, ta/ti, ts/ts respectively. C ₁₁ is a shock absorbing capacitor, generally greater than 200 microfarads.

The output parameters of the parameter measuring device can be sent to the A/D conversion port of the computer or other recording or data acquisition devices, and a monitor can also be installed in the device of the present invention to display these parameters for the operator to observe the processing status. If these five parameters are all displayed in one way, it will make the operator feel dazzled and inconvenient to observe. An application example of a display is provided in FIG. 3 . The display is composed of three meter heads M ₁ , M ₂ , M ₃ and two sets of general luminous level indicator components LED ₁ and LED ₂ . M ₁ displays the "no-load" parameter td/ti, and the adjustable resistor R ₁₆ is used to limit the current and full-scale calibration of M ₁ ; M ₂ displays the "spark discharge" parameter te/ti and "transition unstable arc" The parameters te′/ti are superimposed by the adjustable resistors R ₁₇ and R ₁₈ respectively, that is, the sum of te/ti and te′/ti, and R ₁₇ and R ₁₈ are used for full-scale calibration and current limiting of M ₂ ; Similarly, M ₃ displays the sum of the "stable arc" parameter ta/ti and the "short circuit" parameter ts/ti, and R ₁₉ and R ₂₀ are used for full-scale calibration and current limiting of M ₃ , so the meter head The sum displayed by M ₁ , M ₂ , and M ₃ should be 100%. Light Level Indicator Assembly LED ₁ and LED ₂ display te'/ti and ta/ti parameters respectively. During the processing, the machine tool operator can observe the three heads of _M1 , _M2 and _M3 to understand the basic status of the machine tool processing; when the light-emitting level display LED ₁ indicates that the parameter value increases, it warns the operator that the processing state is deteriorating; when the LED ₂ When the indicated value increases, it means that the "stabilized arc" parameter ta/ti in the machining gap increases, telling the machine tool operator that the surface of the workpiece is burned, and measures need to be taken to eliminate this fault.

Claims (10)

1, a kind of spark machined discharge parameter checkout gear, it is made up of encoder, decoder, parameter measurement device and output interface, and said encoder comprises: voltage sense line; Current sense link and high-frequency detection circuit; Voltage sense line is made up of divider and gate circuit or divider and voltage comparator, the spark machined gap voltage of its input through the divider step-down after gate circuit or voltage comparator form a pulse signal Tu in its output output; Current detector is made up of divider and high-speed light coupling device, and device formation pulse signal Ti exports at its output the spark machined high frequency pulse power supply major loop current-limiting resistance pressure drop signal of its input input after high-speed light is coupled through the divider step-down: the high-frequency detection circuit is made up of high-pass filter, amplifier, demodulator and two voltage comparators; High-pass filter is separated the high frequency signal on the spark machined gap voltage of its input, amplify again through demodulator its detection and filtering through amplifier, form the dc pulse signal that amplitude is proportional to this high fdrequency component amplitude, with two voltage comparators of its pulse signal input, wherein comparative voltage higher voltage comparator is exported the TH signal, the voltage comparator output TL signal that comparative voltage is lower; Said decoder is exported Tu, Ti, TH, the TL signal of encoder output forms Td, Te that instantaneous pulsewidth corresponds to td, te, te ', ta, ts, ti respectively, Te ', Ta, Ts, T Σ through deciphering after pulse signal at its output, it is made up of gate circuit or is formed or be made up of gate circuit and high-speed light coupling device by general decoder and gate circuit, or form by general decoder, gate circuit and high-speed light coupling device, should satisfy following logical relation:

Td=Tu、 Ti

Te=Tu.Ti·TH·TL

Te′=Tu·Ti·TH· TL

Ta=Tu·Ti· TH· TL

Ts= Tu·Ti

T∑=Tu+Ti；

Input input Td, the Te of said parameter measurement device, Te ', Ta, Ts, T Σ pulse signal, the analog quantity voltage of output output td/ti, te/ti, te '/ti, ta/ti, ts/ti parameter; Said output interface is the connection end that links to each other with external equipment of parameter measurement device output or is made up of this connection end and display; Display is made up of adjustable current-limiting resistance and curtage gauge outfit, or is made up of general luminous level indication component; Feature of the present invention is: said parameter measurement device is made up of pulse amplitude modulator 5, mould helium switch 6, low pass filter 7, pulse signal Td, the Te of its input input, Te ', Ta, Ts carry out amplitude by pulse amplitude modulator 5 and become after the iron respectively through being subjected to T ∑ signal controlling only at Ti in the time behind the just closed analog switch 6, and the analog quantity voltage that forms td/ti, te/ti, te '/ti, ta/ti, ts/ti parameter through low pass filter 7 filtering is respectively exported again.

2, the spark machined discharge parameter checkout gear that claim 1 proposed, it is characterized in that: said parameter measurement device also comprises the amplifier 8 that input links to each other with low pass filter 7 outputs, and the parameter signal that low pass filter is exported carries out exporting at its output after the impedance conversion.

3, the spark machined discharge parameter checkout gear that claim 1 and claim 2 are proposed, feature is: said parameter measurement device also comprises fixed ampllitude circuit 10, this fixed ampllitude circuit is by pulse amplitude modulation 13, analog switch 14, low pass filter 15, voltage-stablizer 17 is formed, the T Σ signal of its input input by pulse amplitude modulator 13 amplitude transformation after through being subjected to T Σ signal controlling only just after low pass filter 15 filtering, to transport to the detection input of voltage-stablizer 17 in the time behind the analog switch 14 of closure again at ti, the output of voltage-stablizer 17 links to each other with the power end of pulse amplitude modulator 13, and it is a stationary value that voltage-stablizer 17 regulating impulse modulators 13 output pulse amplitudes make it detect input terminal voltage.

4, the spark machined discharge parameter checkout gear that claim 3 proposed is characterized in that: said fixed ampllitude circuit comprises that also input links to each other with low pass filter 15 outputs, and output detects the amplifier 16 that input links to each other with voltage-stablizer 17.

5, the spark machined discharge parameter checkout gear that proposed of claim 1 and claim 4, it is characterized in that: said pulse amplitude modulator is the CMOS gate circuit; Said analog switch is the MOS analog switch of control end input T Σ signal; Said low pass filter is the RC low-pass first order filter; Amplifier 8 is a voltage follower; The adjustable gain in-phase amplifier of amplifier 16 for constituting by operational amplifier; Voltage-stablizer 17 is the three terminal integrated voltage stabilizer of output negative voltage.

6, a kind of spark machined discharge parameter measurement circuitry, input input pulsewidth respectively synchronously correspondence equal required detector gap state instantaneous time pulse signal and with the pulsewidth ti of spark machined high frequency pulse power supply output pulse and arteries and veins between the T Σ pulse signal that equates synchronously of to, output is exported each measured gap state and distinguished scale parameter interior average time of place ti time, it is characterized in that: this parameter measurement circuit comprises and identical pulse amplitude modulator, analog switch, the low pass filter of need measurement parameter quantity; Analog switch is subjected to T Σ signal controlling only just closed in the time at ti, and output valve remained unchanged when low pass filter disconnected at analog switch; Each road pulse signal of input input is respectively by the analog quantity voltage that is formed on ti each detected gap state respectively shared average time of scale parameter in the time after the pulse amplitude modulator amplitude transformation through analog switch again after low pass filter filtering.

7, the spark machined discharge parameter measurement circuitry that claim 6 proposed, it is characterized in that: this circuit also comprises the amplifier that input links to each other with said low pass filter output, and the parameter signal that low pass filter is exported carries out exporting at its output after the impedance conversion.

8, the spark machined discharge parameter measurement circuitry that proposed of claim 6 and claim 7, it is characterized in that: this circuit also comprises a fixed ampllitude circuit, the fixed ampllitude circuit is by a pulse amplitude modulator, and one is subjected to T Σ signal controlling only just analog switch, a low pass filter that output valve remains unchanged when analog switch disconnects and a voltage-stablizer of closure are formed in the time at ti; The T Σ signal of its input is transported to the detection input of voltage-stablizer after by low pass filter filtering through analog switch after by the pulse amplitude modulator amplitude transformation, and the output of voltage-stablizer links to each other with the power end of pulse amplitude modulator; It is a stationary value that voltage-stablizer regulating impulse modulator output pulse amplitude makes its detection output go into terminal voltage.

9, the spark machined discharge parameter measurement circuitry that claim 8 proposed is characterized in that: said fixed ampllitude circuit comprises that also an input links to each other with said low pass filter output, and output 5 said voltage-stablizers detect the amplifier that input links to each other.

10, the spark machined discharge parameter measurement circuitry that proposed of claim 6 and claim 9, it is characterized in that: said pulse amplitude modulator is the CMOS gate circuit; Said analog switch is the MOS analog switch of control end input T Σ signal; Said low pass filter is the RC low-pass first order filter; The said amplifier that low pass filter output parameter signal is carried out the impedance conversion is a voltage follower; Amplifier in the said fixed ampllitude circuit is an adjustable gain in-phase amplifier that is made of operational amplifier; Said voltage-stablizer is the three terminal integrated voltage stabilizer of output negative voltage.

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