Discharge detection device for an electric discharge machining machine

Abstract

The application discloses a discharge detection device for a discharge machining machine tool, which comprises an NC device, a parameter selection and signal generation device, a rough machining power supply loop, a fine machining power supply loop, a discharge detection device and a feed shaft motor driving control device, and the discharge detection device comprises a decoding circuit, a first driving amplification circuit, a relay module, a branch circuit unit, a sampling signal processing circuit, a V / F conversion circuit, a second driving amplification circuit and a switch relay. In the application, the adjustment method of the sampling reference voltage is realized by receiving three-bit binary codes given by the parameter selection and signal generation device, the V / F conversion of the sampling signal under two different working conditions of rough machining and fine machining is realized by using different filtering, isolating and processing circuits, the discharge detection device is more accurate in judging whether the discharge process occurs in the machining gap, and the sampling of the discharge pulse with a pulse width of less than 1us is more accurate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of discharge detection device, in particular to a discharge detection device for electrical discharge machining machine tool. BACKGROUND

[0002] The discharge detection device is a device for detecting the gap voltage between the wire electrode and the workpiece and converting the analog voltage value into a frequency signal for controlling the feed shaft movement of the electrical discharge machining machine tool. Generally, in order to improve the surface roughness of the finished product produced by electrical discharge machining, multiple steps with different machining conditions are performed. First, the desired profile is roughly formed on the workpiece, then the excess material is removed from the cutting surface with high precision, and finally the cutting surface is finished again to improve the roughness.

[0003] The function of the discharge detection device in the electrical discharge machining machine tool is to determine whether the discharge phenomenon occurs between the wire electrode and the workpiece in real time through the collected voltage pulse signal. In the traditional discharge detection device, the sampling reference voltage value represented by the total voltage value of two series-connected voltage stabilizing diodes is fixed, but in the actual machining process, when the workpiece thickness, material properties and other parameters change or the discharge process between the wire electrode and the workpiece occurs under different working conditions of rough machining and finishing of the same workpiece, the amplitude and pulse width of the gap voltage will change greatly. At this time, the traditional discharge detection device will not be accurate in determining whether the discharge process actually occurs, thereby affecting the machining efficiency and the roughness of the machined surface of the workpiece. SUMMARY

[0004] The purpose of the present application is to provide a discharge detection device for electrical discharge machining machine tool to solve the problems raised in the background.

[0005] In order to solve the above technical problems, the present application provides the following technical scheme:

[0006] The discharge detection device for the electrical discharge machining tool comprises an NC device, a parameter selection and signal generation device connected with the NC device, a rough machining power supply circuit and a fine machining power supply circuit connected with the parameter selection and signal generation device, the rough machining power supply circuit and the fine machining power supply circuit both passing through a workpiece and a metal electrode wire, a machining gap being arranged between the workpiece and the metal electrode wire, a discharge detection device being connected with signal output ends of the rough machining power supply circuit and the fine machining power supply circuit, a feed shaft motor driving control device being connected with the discharge detection device, the discharge detection device comprising a decoding circuit, a first driving amplification circuit, a relay module, a branch circuit unit, a sampling signal processing circuit, a V / F conversion circuit, a second driving amplification circuit and a switching relay, the first driving amplification circuit sending a level signal for driving the relay module, the branch circuit unit comprising a rough machining branch circuit and a fine machining branch circuit, the sampling signal processing circuit comprising an optical isolation device and a current limiting filter protection circuit, and the V / F conversion circuit comprising a rough machining conversion circuit and a fine machining conversion circuit.

[0007] The NC device sends the set relevant machining parameters to the parameter selection and signal generating device through the bus, the parameter selection and signal generating device generates corresponding pulse signal waveforms according to the set relevant parameters to control the rough machining power loop and the fine machining power loop, so as to control the discharge process between the workpiece and the metal electrode wire, the discharge detection device collects the voltage signal sampling signal PM+ and the sampling signal PM- of the electric discharge machining machine tool to judge the current electric discharge machining process and converts the collected voltage pulse signal into a frequency signal through a V / F conversion circuit to send to the servo feed system of the machine tool to control the movement of the machine tool feed shaft, wherein the parameter selection and signal generating device sends a three-bit binary coded digital signal composed of A0, A1 and A2, the parameter selection and signal generating device determines the required sampling reference voltage value and the required sampling filter circuit parameter according to the workpiece thickness, workpiece material type, rough cutting or fine machining state setting and other process parameters sent by the NC device, and then uses one of the eight states represented by the three-bit binary data A0, A1 and A2 to represent, after receiving the three-bit binary coded A0, A1 and A2, the discharge detection device first analyzes it into one of the eight states through a decoding circuit, and then converts it into a level signal capable of driving the relay module through a first drive amplifier circuit, the selection of the optical isolation device in the sampling signal processing circuit and the parameter setting of the current limiting filter protection circuit are mainly used to meet the processing requirements of the rough and fine machining pulse signals, and the filter cutoff frequency set for the fine machining pulse signal processing is much higher than the filter cutoff frequency set for the rough machining pulse signal processing, the pulse frequency signals Pulse_1 and Pulse_2 generated through the branch circuit unit, the sampling signal processing circuit and the V / F conversion circuit are connected to the switch relay respectively, the switch relay is controlled by the signal processed by the second drive amplifier circuit through the highest bit A2 of the three-bit binary coded digital signal, and the pulse frequency signal generated by the currently used sampling circuit can be output to the Pulse_OUT end through the switch relay, and finally the frequency signal output from the Pulse_OUT end is sent to the feed shaft motor drive control device after differential processing, so as to realize the movement control of the servo feed shaft of the electric discharge machining machine tool, the adjustment method of the sampling reference voltage is realized by receiving the three-bit binary code given by the parameter selection and signal generating device, and the V / F conversion of the sampling signal under the conditions of rough and fine machining is realized by using different filter, isolation and processing circuits, so that the discharge detection device can more accurately judge whether the discharge process occurs in the machining gap, and the discharge pulse sampling of less than 1us is more accurate, so that the surface roughness of the machined workpiece is better, and the machining efficiency of the workpiece is higher.

[0008] As a preferred scheme of the present application, the relay module is composed of eight relays K1 to K8.

[0009] The above technical solution is realized, one common end of the eight relay switch contacts is connected to the sampling signal PM+, the other end is in the form of normally open contact, one of the eight relays is closed according to the driving control signal given by the first driving amplifier circuit each time, and it is ensured that PM+ can only be connected to one of the rear end rough machining branch circuit and the fine machining branch circuit.

[0010] As a preferred scheme of the present application, the branch circuit unit is composed of four groups of series-connected voltage stabilizing diodes.

[0011] The above technical solution is realized, the model of the diode is selected according to the required total voltage stabilizing value, the total voltage stabilizing value is set according to the judgment threshold voltage value of the gap discharge phenomenon under different working conditions, the sampling signal processing circuit connected to the rear end of the rough machining branch circuit mainly meets the setting requirement of the sampling voltage during rough machining, so the total voltage stabilizing value is generally set to 20V, 22V, 24V, 27V, the sampling signal processing circuit connected to the rear end of the fine machining branch circuit mainly meets the setting requirement of the sampling voltage during fine machining, so the total voltage stabilizing value is generally set to 13V, 15V, 16V, 18V, and a power resistor is connected to the sampling signal PM- end of each branch in the fine machining branch circuit.

[0012] As a preferred scheme of the present application, CD4046BCN conversion chip is selected in the rough machining conversion circuit, and LM331AN conversion chip is selected in the fine machining conversion circuit.

[0013] The above technical solution is realized, the rough machining conversion circuit and the fine machining conversion circuit meet the V / F conversion requirement of the sampling voltage signal.

[0014] As a preferred scheme of the present application, the rough machining power loop includes a rough machining MOS tube unit, a current-limiting resistor, a rough machining voltage source and a rough machining anti-backflow diode, and the fine machining power loop includes a fine machining MOS tube unit, a fine machining voltage source and a fine machining anti-backflow diode.

[0015] The above technical solution is realized, the on and off of the corresponding number of MOS tubes in the rough machining MOS tube unit composed of multiple parallel MOS tubes and the fine machining MOS tube unit composed of multiple parallel MOS tubes realize the purpose of controlling the discharge process of the machining gap between the workpiece and the metal electrode wire, the voltage amplitude of the rough machining voltage source and the fine machining voltage source is adjustable, the voltage adjustment is realized by receiving the setting value from the parameter selection and signal generation device, and the rough machining anti-backflow diode and the fine machining anti-backflow diode prevent the pulse voltage spike generated when the rough machining MOS tube unit and the fine machining MOS tube unit are turned off from damaging the rough machining voltage source and the fine machining voltage source.

[0016] In summary, the present application has the following advantages: the NC device sends the set relevant processing parameters to the parameter selection and signal generating device through the bus, the parameter selection and signal generating device generates corresponding pulse signal waveforms according to the set relevant parameters to control the rough machining power loop and the fine machining power loop to achieve the purpose of controlling the discharge process between the workpiece and the metal electrode wire, the discharge detection device judges the current discharge machining process by collecting the voltage signal sampling signal PM+ and the sampling signal PM- through the discharge machining machine tool and converts the collected and processed voltage pulse signal into a frequency signal through the V / F conversion circuit to send to the servo feed system of the machine tool to control the movement of the machine tool feed shaft, wherein the parameter selection and signal generating device sends a three-bit binary coded digital signal composed of A0, A1 and A2, the parameter selection and signal generating device determines the required sampling reference voltage value and the required sampling filter circuit parameters according to the workpiece thickness, workpiece material type, rough cutting or fine finishing state setting and other process parameters issued by the NC device, and then uses one of the eight states represented by the A0, A1 and A2 three-bit binary data to represent, after receiving the A0, A1 and A2 three-bit binary code, the discharge detection device first analyzes it into one of the eight states through the decoding circuit, and then converts it into a level signal that can drive the relay module to act through the first drive amplifier circuit, the selection of the optical isolation device in the sampling signal processing circuit and the parameter setting of the current limiting filter protection circuit are mainly used to meet the processing requirements of the rough and fine machining pulse signals, and the filter cutoff frequency set for the fine machining pulse signal processing is much higher than the filter cutoff frequency set for the rough machining pulse signal processing, after generating the pulse frequency signals Pulse_1 and Pulse_2 through the branch circuit unit, the sampling signal processing circuit and the V / F conversion circuit, the signals are connected to the switch relays, the switch relays are controlled by the signal processed by the second drive amplifier circuit through the highest bit A2 of the three-bit binary coded digital signal, and the pulse frequency signals generated by the currently used sampling circuit can be output to the Pulse_OUT terminal through the switch relays, and finally the frequency signal output from the Pulse_OUT terminal is sent to the feed shaft motor drive control device after differential processing to realize the movement control of the servo feed shaft of the discharge machining machine tool, the adjustment method of the sampling reference voltage is realized by receiving the three-bit binary code given by the parameter selection and signal generating device, and the method of using different filter, isolation and processing circuits for V / F conversion of the sampling signal under the conditions of rough and fine machining is used to realize the discharge detection device to more accurately judge whether the discharge process occurs in the machining gap, and more accurately sample the discharge pulse with a pulse width of less than 1us, so that the surface roughness of the machined workpiece is better and the machining efficiency of the workpiece is higher. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification, illustrate embodiments of the application, and together with the description serve to explain the application, and do not limit the application. In the drawings:

[0018] Fig. 1 is a basic block diagram of the application;

[0019] Fig. 2 is a structural schematic diagram of the discharge detection device in the application;

[0020] In the figure: 1 is a rough machining voltage source; 2 is a fine machining voltage source; 3 is a fine machining anti-reverse flow diode; 4 is a rough machining anti-reverse flow diode; 5 is a flow resistance; 6 is a rough machining MOS tube unit; 7 is a fine machining MOS tube unit; 8 is a workpiece; 9 is a machining gap; 10 is a metal electrode wire; 11 is a sampling signal PM+; 12 is a sampling signal PM-; 13 is a parameter selection and signal generation device; 14 is an NC device; 15 is a discharge detection device; 16 is a feed shaft motor drive control device; 17 is a decoding circuit; 18 is a first drive amplification circuit; 19 is a relay module; 20 is a rough machining branch circuit; 21 is a fine machining branch circuit; 22 is a sampling signal processing circuit; 24 is a rough machining conversion circuit; 25 is a fine machining conversion circuit; 26 is a switch relay; 27 is a second drive amplification circuit. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the application.

[0022] EMBODIMENT

[0023] Please refer to Figs. 1-2The present application provides a kind of discharge detection device 15 for electrical discharge machining machine tool, including NC device 14, NC device 14 is connected with parameter selection and signal generating device 13, parameter selection and signal generating device 13 is connected with rough machining power supply loop and finishing power supply loop, rough machining power supply loop and finishing power supply loop are all through workpiece 8 and metal electrode wire 10, and processing gap 9 is arranged between workpiece 8 and metal electrode wire 10, rough machining power supply loop and finishing power supply loop signal output end are connected with discharge detection device 15, discharge detection device 15 is connected with feed shaft motor drive control device 16, discharge detection device 15 includes decoding circuit 17, first drive amplifier circuit 18, relay module 19, branch circuit unit, sampling signal processing circuit 22, V / F conversion circuit, second drive amplifier circuit 27, switch relay 26, first drive amplifier circuit 18 sends the level signal of driving relay module 19, branch circuit unit includes rough machining branch circuit 20 and finishing branch circuit 21, sampling signal processing circuit 22 includes optical isolator and current-limiting filter protection circuit, V / F conversion circuit includes rough machining conversion circuit 24 and finishing conversion circuit 25.

[0024] Relay module 19 is composed of eight relays K1 to K8, one common end of the switching contacts of the eight relays is connected to the sampling signal PM+, and the other end is in the form of a normally open contact. Each time, one of the eight relays is closed according to the drive control signal given by the first drive amplifier circuit 18, ensuring that PM+ can only be connected to one of the rough machining branch circuit 20 and the finishing branch circuit 21 at the back end.

[0025] The branch circuit unit is composed of four groups of series-connected zener diodes. The model of the diodes is selected according to the required total zener voltage, which is set according to the judgment threshold voltage value of the gap discharge phenomenon under different working conditions. The sampling signal processing circuit 22 connected at the back end of the rough machining branch circuit 20 mainly meets the setting requirements of the sampling voltage during rough machining, so the total zener voltage is generally set to 20V, 22V, 24V, and 27V. The sampling signal processing circuit 22 connected at the back end of the finishing branch circuit 21 mainly meets the setting requirements of the sampling voltage during finishing, so the total zener voltage is generally set to 13V, 15V, 16V, and 18V. Each branch of the finishing branch circuit 21 is also connected to a power resistor at the PM- end.

[0026] The CD4046BCN conversion chip is selected in the rough machining conversion circuit 24, and the LM331AN conversion chip is selected in the finishing conversion circuit 25. The rough machining conversion circuit 24 and the finishing conversion circuit 25 meet the V / F conversion requirements of the sampling voltage signal.

[0027] The coarse machining power circuit comprises a coarse machining MOS tube unit 6, a current-limiting resistor 5, a coarse machining voltage source 1 and a coarse machining anti-reverse flow diode 4, and the fine machining power circuit comprises a fine machining MOS tube unit 7, a fine machining voltage source 2 and a fine machining anti-reverse flow diode 3. The turn-on and turn-off of the corresponding number of MOS tubes in the coarse machining MOS tube unit 6 composed of a plurality of parallel MOS tubes and the fine machining MOS tube unit 7 composed of a plurality of parallel MOS tubes achieve the purpose of controlling the discharge process of the machining gap 9 between the workpiece 8 and the metal electrode wire 10. The voltage amplitude of the coarse machining voltage source 1 and the fine machining voltage source 2 is adjustable, and the adjustment of the voltage is realized by receiving the set value from the parameter selection and signal generation device 13. The coarse machining anti-reverse flow diode 4 and the fine machining anti-reverse flow diode 3 prevent the pulse voltage spike generated when the coarse machining MOS tube unit 6 and the fine machining MOS tube unit 7 are turned off from damaging the coarse machining voltage source 1 and the fine machining voltage source 2.

[0028] In the embodiment of the present application, the NC device 14 sends the set relevant processing parameters to the parameter selection and signal generating device 13 through the bus, the parameter selection and signal generating device 13 generates corresponding pulse signal waveforms according to the set relevant parameters to control the rough machining power loop and the fine machining power loop to achieve the purpose of controlling the discharge process of the machining gap 9 between the workpiece 8 and the metal electrode wire 10, the discharge detection device 15 judges the current discharge machining process occurrence by collecting the voltage signal sampling signals PM+ 11 and PM- 12 passing through the electric discharge machining machine tool and converts the collected and processed voltage pulse signals into frequency signals through a V / F conversion circuit to send to the servo feed system of the machine tool to control the movement of the machine tool feed shaft, wherein the parameter selection and signal generating device 13 sends a three-bit binary coded digital signal composed of A0, A1, and A2, the parameter selection and signal generating device 13 determines the required sampling reference voltage value and the required sampling filter circuit parameters according to the workpiece 8 thickness, workpiece 8 material type, rough cutting or finishing state setting and other process parameters issued by the NC device 14, and then uses one of the eight states represented by the A0, A1, and A2 three-bit binary data to represent, after receiving the A0, A1, and A2 three-bit binary code, the discharge detection device 15 first analyzes it into one of the eight states through the decoding circuit 17, and then converts it into a level signal that can drive the relay module 19 to act through the first drive amplifier circuit 18, the selection of the optical isolation device in the sampling signal processing circuit 22 and the setting of the current limiting filter protection circuit parameters are mainly used to meet the processing requirements of the rough and fine machining pulse signals, wherein the filter cutoff frequency set for the fine machining pulse signal processing is much higher than the filter cutoff frequency set for the rough machining pulse signal processing, after passing through the branch circuit unit, the sampling signal processing circuit 22, and the V / F conversion circuit to generate pulse frequency signals Pulse_1 and Pulse_2, which are connected to the switch relay 26, the switch relay 26 is controlled by the signal processed by the second drive amplifier circuit 27 through the highest bit A2 of the three-bit binary coded digital signal, and the pulse frequency signal generated by the currently used sampling circuit can be output to the Pulse_OUT terminal through the switching of the switch relay 26, and finally the frequency signal output from the Pulse_OUT terminal is sent to the feed shaft motor drive control device 16 after differential processing to realize the movement control of the servo feed shaft of the electric discharge machining machine tool, the adjustment method of the sampling reference voltage is realized by receiving the three-bit binary code given by the parameter selection and signal generating device 13, and the method of using different filter, isolation, and processing circuits for V / F conversion of the sampling signal under two different working conditions of rough and fine machining is used to make the judgment of the discharge process of the machining gap 9 by the discharge detection device 15 more accurate, and the sampling of the discharge pulse with a pulse width below 1us is more accurate, so that the surface roughness of the machined workpiece 8 is better, and the machining efficiency of the workpiece 8 is higher.

[0029] It should be noted that the relationship terms, such as first and second, and the like, are used only to differentiate one entity or action from another, and do not necessarily require or imply any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0030] Finally, it should be noted that the above-described embodiments are merely possible implementations of the present application, but not to be taken to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, the technical solutions recorded in the foregoing embodiments can still be modified by those skilled in the art, or some technical features thereof can be replaced by equivalent replacements. Any modifications, equivalent replacements, improvements, and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A discharge detection device for an electrical discharge machine tool, characterized in that: The NC device includes an NC device, the NC device is connected to a parameter selection and signal generating device, the parameter selection and signal generating device is connected to a roughing power supply circuit and a fine machining power supply circuit, the roughing power supply circuit and the fine machining power supply circuit both pass through a workpiece and a metal electrode wire, a machining gap is provided between the workpiece and the metal electrode wire, the signal output ends of the roughing power supply circuit and the fine machining power supply circuit are connected to a discharge detection device, the discharge detection device is connected to a feed axis motor drive control device, the discharge detection device includes a decoding circuit, a first drive amplifier circuit, a relay module, a branch circuit unit, a sampling signal processing circuit, a V / F conversion circuit, a second drive amplifier circuit, and a switch relay, the first drive amplifier circuit emits a signal that drives the relay The module's level signal, the branch circuit unit includes a roughing branch circuit and a fine-machining branch circuit, the sampling signal processing circuit includes an optical isolator and a current limiting filter protection circuit, the V / F conversion circuit includes a roughing conversion circuit and a fine-machining conversion circuit, the branch circuit unit is composed of four groups of voltage-stabilizing diodes connected in series, the roughing power supply circuit includes a roughing MOS tube unit, a blocking resistor, a roughing voltage source, and a roughing anti-backflow diode, the fine-machining power supply circuit includes a fine-machining MOS tube unit, a fine-machining voltage source, and a fine-machining anti-backflow diode, each branch in the fine-machining branch circuit is connected to a power resistor for the sampling signal terminal PM-terminal, and the roughing MOS tube unit and the fine-machining MOS tube unit are composed of MOS tubes connected in parallel.

2. The discharge detection device for an electric discharge machine tool according to claim 1, wherein: The relay module consists of eight relays from K1 to K8.

3. The discharge detection device for an electric discharge machine tool according to claim 2, wherein: The CD4046BCN conversion chip is selected in the rough processing conversion circuit, and the LM331AN conversion chip is selected in the fine processing conversion circuit.

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