Electric spark constant current pulse power supply

Abstract

The present application relates to the technical field of electric spark machining, and discloses an electric spark constant-current pulse power supply, which comprises: a parameter interface, which is used for receiving machining parameters, and the machining parameters at least include a target discharge current and a target discharge voltage; a control module, which is used for determining a target equivalent current-limiting resistor according to the target discharge current and the target discharge voltage, and outputting a resistor selection control signal; a resistor array, which comprises a plurality of resistor branches; a selection switch assembly, which selectively inputs or bypasses the plurality of resistor branches under the action of the resistor selection control signal; and a pulse power switch device, which is connected in series in a discharge circuit and outputs a discharge pulse under the driving of the control module. The resistor array and the selection switch assembly form a switchable equivalent current-limiting resistance value, the control module outputs the resistor selection control signal according to the target discharge current and the target discharge voltage, and the equivalent resistance value is synchronously switched when the voltage changes, so that the output current of the discharge circuit is maintained in a preset range of the target current.

Description

Technical Field

[0001] This invention relates to the field of electrical discharge machining technology, specifically to a constant current pulse power supply for electrical discharge machining. Background Technology

[0002] A constant current pulse power supply is a key power supply device in an EDM system. It is used to output pulsed discharge energy between the electrode and the workpiece to achieve material removal and shaping. A constant current pulse power supply is a power supply form that constrains and regulates the discharge current based on pulsed power supply. The aim is to make the current during the discharge process closer to the set target, thereby improving machining stability and quality. Existing EDM power supplies typically use constant voltage power supply combined with current-limiting components or control strategies to achieve current control.

[0003] However, in current technology, since the inter-electrode voltage fluctuates with the state of the discharge gap during the processing, the existing constant voltage power supply combined with current limiting is difficult to adjust the current limiting condition synchronously when the voltage changes. This can easily lead to sudden changes in the inter-electrode output current, thereby affecting the discharge stability and the quality of the processed surface. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an electrical discharge constant current pulse power supply, which solves the problem of sudden changes in the output current of the discharge circuit caused by changes in the target discharge voltage during the processing.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an electrical spark constant current pulse power supply, comprising: A parameter interface is used to receive processing parameters, which include at least the target discharge current and the target discharge voltage. The control module is used to determine the target equivalent current limiting resistor based on the target discharge current and the target discharge voltage, and output a resistor selection control signal; A resistor array containing multiple resistor branches; The selection switch assembly is configured corresponding to the resistor array and is used to selectively engage or bypass the plurality of resistor branches under the action of the resistor selection control signal, so as to form an equivalent resistance value that matches the target equivalent current limiting resistor. A pulse power switching device is connected in series in the discharge circuit to output discharge pulses under the drive of the control module; When the target discharge voltage changes, the control module changes the conduction combination of the selection switch assembly to change the equivalent resistance value, so that the output current of the discharge circuit is maintained within the preset range of the target current.

[0006] Preferably, the control module is used to select the resistor branch combination corresponding to the target equivalent current limiting resistor after determining the target equivalent current limiting resistor, and control the selection switch component to turn on the switch combination corresponding to the resistor branch combination.

[0007] Preferably, the resistor array includes multiple resistor branches with different resistance values, which are used to form multiple equivalent resistance values ​​by being connected in series.

[0008] Preferably, the resistor array includes at least a number of resistor branches with different resistance values, and the set of resistance values ​​of the resistor branches is used to cover the required equivalent resistance range.

[0009] Preferably, the selection switch assembly includes a switch unit corresponding to the resistor branch, the number of switch units corresponds to the number of resistor branches, and each switch unit is used to control the connection or bypass of the corresponding resistor branch.

[0010] Preferably, under the condition that the target discharge current remains unchanged, when the target discharge voltage is at a first set value, the selection switch assembly is controlled to form a first equivalent resistance value; When the target discharge voltage changes to the second set value, the selection switch assembly is controlled to form a second equivalent resistance value different from the first equivalent resistance value, so that the output current is maintained within the preset range of the target discharge current.

[0011] Preferably, the first equivalent resistance value is formed by combining at least two resistor branches, the second equivalent resistance value is formed by combining at least two resistor branches, and the resistor branch combination used to form the first equivalent resistance value is different from the resistor branch combination used to form the second equivalent resistance value.

[0012] Preferably, the control module includes a processing parameter parsing unit, used to parse the received processing parameters and generate the resistor selection control signal, wherein the resistor selection control signal is generated by a software algorithm.

[0013] Preferably, the pulse power switching device is a MOS transistor, which is used to generate a discharge pulse during the conduction period and a pulse interval during the turn-off period to provide energy for pulse discharge between the electrode and the workpiece.

[0014] Preferably, the selection switch assembly includes a drive isolation unit for electrically isolating the control signal of the control module from the selection switch assembly, so as to drive the selection switch assembly to selectively engage or bypass the resistor branch.

[0015] This invention provides an electrical spark constant current pulse power supply. It has the following beneficial effects: 1. The present invention forms a switchable equivalent current limiting resistance value through a resistor array and a selection switch component. The control module outputs a control signal based on the target discharge current and the target discharge voltage, and synchronously switches the equivalent resistance value when the voltage changes, so that the output current of the discharge circuit is maintained within the preset range of the target current.

[0016] 2. This invention achieves graded current limiting by combining resistor branches and switches. The resistor array is composed of branches with various resistance values ​​and can be connected in series to form multiple equivalent resistance values, which is convenient for adapting to different processing parameters, reducing current surges caused by voltage fluctuations, and improving discharge stability and processing consistency.

[0017] 3. The present invention sets up a drive isolation unit between the control module and the selection switch assembly to achieve electrical isolation between the control signal and the power side, reduce the impact of discharge interference on the control side, improve the reliability of switch switching and constant current control, and enhance the stable operation capability of the power supply in the EDM environment. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the electrical discharge constant current pulse power supply of the present invention. Figure 2 This is the equivalent circuit diagram of the main power supply circuit of the present invention; Figure 3 This is a schematic diagram of the resistor switching and isolation drive circuit of the present invention. Detailed Implementation

[0019] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see the appendix Figure 1 - Appendix Figure 3 This invention provides an electrical spark constant current pulse power supply, comprising: The parameter interface is used to receive processing parameters, which include at least the target discharge current and the target discharge voltage. The control module is used to determine the target equivalent current-limiting resistor based on the target discharge current and the target discharge voltage, and output a resistor selection control signal. A resistor array containing multiple resistor branches; Select the switch component, which is set up in correspondence with the resistor array, to selectively connect or bypass multiple resistor branches under the action of the resistor selection control signal, so as to form an equivalent resistance value that matches the target equivalent current limiting resistor. A pulse power switching device is connected in series in the discharge circuit to output discharge pulses under the drive of the control module; When the target discharge voltage changes, the control module changes the conduction combination of the selection switch components to change the equivalent resistance value, so that the output current of the discharge circuit is maintained within the preset range of the target current.

[0021] Specifically, the power supply establishes a communication connection with the CNC device or machining control terminal, obtains the setting values ​​related to the machining process through the parameter interface, and sends the setting values ​​to the control module as the control basis. The parameter interface mainly completes the reception and transmission of parameters, so that the control module can obtain the target quantity corresponding to the machining process, thereby ensuring that the subsequent current limiting matching and pulse output have a unified parameter source, and avoiding discontinuity in the control link due to parameter dispersion. The control module analyzes the set values ​​from the parameter interface to obtain the equivalent current-limiting resistance value that needs to be matched, and generates a control signal for driving resistor switching. The control module can be implemented using digital control logic or a controller, and internally includes resistor combination selection logic: it determines the resistor branch combination to be engaged based on the analysis results and outputs the corresponding switch drive command. When the set discharge voltage changes, the control module synchronously updates the matched equivalent resistance value and the switch drive command, adjusting the equivalent resistance value of the resistor array accordingly. This keeps the discharge circuit current within the preset allowable fluctuation range of the target current. Through this linkage method, "parameter changes" can be directly mapped to "resistance changes," suppressing the impact of voltage changes on the discharge current and improving processing stability. The resistor array is set on the current-limiting path of the discharge circuit and consists of multiple resistor branches with different resistance values. It is used to provide equivalent resistance values ​​in different ranges. After different resistor branches are selectively connected, they form the required equivalent resistance values, so that the discharge circuit still has the corresponding current-limiting capability under different voltage settings. When the equivalent resistance value is updated, the current-limiting condition of the discharge circuit changes accordingly, thereby constraining current fluctuations, reducing the probability of current sudden changes caused by inter-electrode voltage changes, and improving discharge consistency and texture quality. The selection switch assembly is arranged corresponding to each resistor branch. Under the action of the control signal, the connection state of the resistor branch can be changed, thereby realizing the switching of the equivalent resistance value of the resistor array. The selection switch assembly can be composed of multiple switch units. Each switch unit cooperates with the corresponding resistor branch to switch the resistor branch between the input circuit and the bypass circuit, so as to obtain the combination corresponding to the target equivalent resistance value. In order to improve anti-interference and safety, the control signal can be driven by isolation before being applied to the switch unit, so that the control side and the power side are electrically isolated. With the help of the selection switch assembly, the "combination command" output by the control module is converted into "branch state", thereby ensuring that the execution result of the resistance value switching is consistent with the target equivalent resistance value determined by the control module. A pulsed power switch is connected in series in the discharge circuit. Driven by the control module, it realizes the pulsed supply of discharge energy. The pulsed power switch can be a MOSFET. The control module drives the output gate of the MOSFET with a pulse, which makes it periodically turn on and off. During the on period, a discharge pulse is formed, and during the off period, a pulse interval is formed, realizing the pulsed discharge energy supply between the electrode and the workpiece. The resistor array and the equivalent resistance formed by its switching work together with the pulsed power switch: the former provides the current limiting condition that matches the set value, and the latter completes the pulse output and circuit on / off control. Thus, when the voltage setting changes, the current can still be kept stable by switching the resistance value, thereby reducing the sudden change of output current, improving discharge stability and the consistency of the processed surface.

[0022] The resistor array includes resistor branches with different resistance values, which are used to form multiple equivalent resistance values ​​by being connected in series.

[0023] Specifically, after determining the target equivalent current-limiting resistor, the control module further executes the process of resistor branch combination selection and switch combination control: First, it reads or calls the resistance value information of each resistor branch in the resistor array and selects the one-to-one correspondence between the switch component and the resistor branch; then, taking the target equivalent current-limiting resistor as the matching target, it selects the resistor branch combination that can form the target equivalent current-limiting resistor as the target combination, and generates the switch conduction state corresponding to the target combination accordingly; finally, it outputs the switch conduction state as a resistor selection control signal, drives the selection switch component to conduct the switch unit corresponding to the target combination, so that the resistor branch corresponding to the target combination is put into the current-limiting path and the other resistor branches are bypassed, thereby forming an equivalent resistance value that matches the target equivalent current-limiting resistor; when the target equivalent current-limiting resistor changes with the update of processing parameters, the control module synchronously updates the resistor branch combination and switch combination to realize the switching of the equivalent resistance value to maintain the output current stable within the preset range.

[0024] The resistor array includes resistor branches with different resistance values, which are used to form multiple equivalent resistance values ​​by being connected in series.

[0025] Specifically, the resistor array consists of multiple resistor branches with different resistance values, arranged on the current-limiting path of the discharge circuit. With the cooperation of the selective switching component, several resistor branches can be selectively connected to the circuit, so that the connected resistor branches are superimposed in series to form a corresponding equivalent resistance value. By changing the resistance value combination and number of resistor branches connected to the circuit, different levels of equivalent resistance values ​​can be obtained, realizing multi-level current-limiting output conditions. When the target equivalent current-limiting resistance changes, it can switch to the matching equivalent resistance value, thereby constraining the discharge circuit current in different levels and improving the adaptability and stability of the constant current pulse output.

[0026] The resistor array includes at least several resistor branches with different resistance values, and the set of resistance values ​​of the resistor branches is used to cover the required range of equivalent resistance values.

[0027] Specifically, in order for the resistor array to cover the range of equivalent resistance values ​​required for processing, in one embodiment, the resistor array is provided with at least a variety of resistor branches with different resistance values ​​as basic resistance units; for example, the resistor array may include resistor branches with resistance values ​​of 50Ω, 30Ω, 10Ω, 10Ω, 100Ω, 60Ω, 20Ω, and 20Ω. Based on the above set of resistance values, under the control of the selective switching component, different resistor branches can be selectively connected and combined in series to form multiple equivalent resistance values ​​and cover the required range of the target equivalent current limiting resistor. For example, two 10Ω branches can be combined to form a 20Ω range, two 20Ω branches can be combined to form a 40Ω range, and the range of equivalent resistance values ​​that can be formed can be expanded by using different combinations of 30Ω, 50Ω, 60Ω, and 100Ω branches with 10Ω or 20Ω branches to meet the current limiting matching requirements under different processing parameters.

[0028] The selector switch assembly includes switch units corresponding to resistor branches. The number of switch units corresponds to the number of resistor branches, and each switch unit is used to control the connection or bypass of the corresponding resistor branch.

[0029] Specifically, the switching components are matched with the resistor array, and each resistor branch in the resistor array is equipped with a corresponding switching unit, so that the number of switching units corresponds to the number of resistor branches. In one embodiment, the resistor array is equipped with 8 resistor branches (e.g., 50Ω, 30Ω, 10Ω, 10Ω, 100Ω, 60Ω, 20Ω, and 20Ω respectively), and the corresponding switching components are equipped with 8 switching units and connected to the above resistor branches. When the control module outputs the resistor selection control signal, it controls the state of each switching unit to realize the "on / bypass" switching of the corresponding resistor branch: when a resistor branch needs to participate in forming the target equivalent resistance value, its corresponding switching unit is controlled to put the resistor branch in the on state and connect it to the current limiting path. When a resistor branch needs to participate in forming the target equivalent resistance value, its corresponding switching unit is controlled to put the resistor branch into the active state and connect it to the current limiting path; when a resistor branch does not need to participate in forming the equivalent resistance value, its corresponding switching unit is controlled to put the resistor branch into the bypass state and not participate in the loop current limiting. Through the structural relationship of "one-to-one correspondence between switching units and resistor branches", the resistor branch combination selection result of the control module can be converted into the actual connection state of each resistor branch, thereby realizing the graded switching of the equivalent resistance value of the resistor array and the rapid matching of constant current limiting conditions.

[0030] Under the condition that the target discharge current remains unchanged, when the target discharge voltage is at a first set value, the control selection switch assembly forms a first equivalent resistance value; When the target discharge voltage changes to the second set value, the control selection switch assembly forms a second equivalent resistance value that is different from the first equivalent resistance value, so that the output current is maintained within the preset range of the target discharge current.

[0031] Specifically, under the condition that the target discharge current remains unchanged, the control module matches and switches the equivalent resistance value of the resistor array according to the set value of the current target discharge voltage: when the target discharge voltage is at the first set value, the control module determines the first equivalent resistance value corresponding to the first set value, and outputs a resistor selection control signal to drive the selection switch component to switch to the switch combination corresponding to the first equivalent resistance value, so that the resistor array forms the first equivalent resistance value as the current limiting condition of the discharge circuit; When the target discharge voltage changes to the second set value, the control module synchronously updates the required equivalent resistance value and outputs the corresponding resistance selection control signal to drive the selection switch component to switch to the switch combination corresponding to the second equivalent resistance value, so that the resistor array forms a second equivalent resistance value different from the first equivalent resistance value. By switching the equivalent resistance value in conjunction with the change of the target voltage setting, the current limiting condition of the discharge circuit is adjusted accordingly. Thus, even when the voltage setting changes, the output current is still constrained within the preset range of the target discharge current, reducing the current surge caused by voltage changes and improving discharge stability and processing consistency.

[0032] The first equivalent resistance value is formed by combining at least two resistor branches, and the second equivalent resistance value is formed by combining at least two resistor branches, wherein the combination of resistor branches used to form the first equivalent resistance value is different from the combination of resistor branches used to form the second equivalent resistance value.

[0033] Specifically, in order to achieve the switching of equivalent resistance values ​​under different target discharge voltage settings, both the first equivalent resistance value and the second equivalent resistance value are formed by combining multiple resistor branches: when it is necessary to form the first equivalent resistance value, the control module controls the selection switch component to put at least two resistor branches into the current limiting path and combine them to obtain the first equivalent resistance value. When it is necessary to form a second equivalent resistance value, the control module controls the selection switch assembly to put at least two resistor branches into the current limiting path and combine them to obtain the second equivalent resistance value. The combination of resistor branches used to form the second equivalent resistance value is different from the combination of resistor branches used to form the first equivalent resistance value. By means of the above method, different combinations of resistor branches can be switched according to the changes in the target discharge voltage while keeping the target discharge current constant, so that the resistor array forms an equivalent resistance value corresponding to each set value, so as to match and limit the discharge circuit current and keep the output current stable within the preset range.

[0034] The control module includes a processing parameter parsing unit, which is used to parse the received processing parameters and generate a resistance selection control signal, and the resistance selection control signal is generated by a software algorithm.

[0035] Specifically, the control module is equipped with a processing parameter parsing unit to parse the processing parameters received by the parameter interface, obtain the target quantity for resistor matching, and generate a resistor selection control signal accordingly. The processing parameter analysis unit is implemented in software. The software algorithm running inside it determines the combination of resistor branches to be put into operation based on the target discharge current, target discharge voltage, and the resistance configuration of the resistor array and the correspondence between the switch obtained by analysis, and outputs the corresponding switch conduction state as a resistor selection control signal, thereby driving the selection switch component to complete the input or bypass of the resistor branch, and realize the matching of the equivalent resistance value of the resistor array with the target equivalent current limiting resistor.

[0036] The pulse power switching device is a MOSFET. The MOSFET is used to generate discharge pulses during the conduction period and pulse intervals during the turn-off period, which is used to supply energy for pulse discharge between the electrode and the workpiece.

[0037] Specifically, the pulse power switching device uses a MOSFET connected in series in the discharge circuit. The gate of the MOSFET is connected to the drive output terminal of the control module. The control module outputs a pulse drive signal to the MOSFET, causing the MOSFET to periodically turn on and off. During the on-time, a discharge path is established between the power supply and the electrode and workpiece, forming a discharge pulse. During the off-time, the discharge path is cut off, forming a pulse interval, thereby realizing pulse discharge power supply between the electrode and the workpiece. The on-off process of the MOSFET is coordinated with the equivalent current limiting condition formed by the resistor array, so that the output current of the discharge pulse meets the processing pulse power supply requirements while being constrained by the equivalent resistance value, thereby improving the stability of the discharge process and the consistency of processing.

[0038] The selector switch assembly includes a drive isolation unit for electrically isolating the control signals from the control module from the selector switch assembly, so as to drive the selector switch assembly to selectively engage or bypass the resistor branch.

[0039] Specifically, a drive isolation unit is incorporated into the selector switch assembly. The input of this drive isolation unit is connected to the control signal output of the control module, and its output is connected to the drive terminal of each switch unit. This isolates the resistance selection control signal output by the control module from the selector switch assembly before driving it. During operation, the control module outputs a switch on / off command. The drive isolation unit transmits this command in isolation and generates a corresponding drive signal, which in turn drives the switch units of the selector switch assembly to activate or bypass the corresponding resistor branch, thus switching the equivalent resistance value of the resistor array. By incorporating the drive isolation unit, the impact of power circuit interference on the control side is reduced, improving the reliability of control signal transmission and the stability of system operation.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A constant current pulse power supply for electrical discharge machining, characterized in that, include: A parameter interface is used to receive processing parameters, which include at least the target discharge current and the target discharge voltage. The control module is used to determine the target equivalent current limiting resistor based on the target discharge current and the target discharge voltage, and output a resistor selection control signal; A resistor array containing multiple resistor branches; The selection switch assembly is configured corresponding to the resistor array and is used to selectively engage or bypass the plurality of resistor branches under the action of the resistor selection control signal, so as to form an equivalent resistance value that matches the target equivalent current limiting resistor. A pulse power switching device is connected in series in the discharge circuit to output discharge pulses under the drive of the control module; When the target discharge voltage changes, the control module changes the conduction combination of the selection switch assembly to change the equivalent resistance value, so that the output current of the discharge circuit is maintained within the preset range of the target current.

2. The electrical discharge constant current pulse power supply according to claim 1, characterized in that, The control module is used to select the resistor branch combination corresponding to the target equivalent current limiting resistor after determining the target equivalent current limiting resistor, and control the selection switch component to turn on the switch combination corresponding to the resistor branch combination.

3. The electrical discharge constant current pulse power supply according to claim 1, characterized in that, The resistor array includes resistor branches with different resistance values, which are used to form multiple equivalent resistance values ​​by being connected in series.

4. The electrical discharge constant current pulse power supply according to claim 3, characterized in that, The resistor array includes at least several resistor branches with different resistance values, and the set of resistance values ​​of the resistor branches is used to cover the required equivalent resistance range.

5. The electrical discharge constant current pulse power supply according to claim 1, characterized in that, The selection switch assembly includes a switch unit corresponding to the resistor branch, the number of switch units corresponding to the number of resistor branches, and each switch unit is used to control the connection or bypass of the corresponding resistor branch.

6. The electrical discharge constant current pulse power supply according to claim 1, characterized in that, Under the condition that the target discharge current remains unchanged, when the target discharge voltage is at a first set value, the selection switch assembly is controlled to form a first equivalent resistance value; When the target discharge voltage changes to the second set value, the selection switch assembly is controlled to form a second equivalent resistance value different from the first equivalent resistance value, so that the output current is maintained within the preset range of the target discharge current.

7. The electrical discharge constant current pulse power supply according to claim 6, characterized in that, The first equivalent resistance value is formed by combining at least two resistor branches, and the second equivalent resistance value is formed by combining at least two resistor branches, wherein the resistor branch combination used to form the first equivalent resistance value is different from the resistor branch combination used to form the second equivalent resistance value.

8. The electrical discharge constant current pulse power supply according to claim 1, characterized in that, The control module includes a processing parameter parsing unit, which is used to parse the received processing parameters and generate the resistor selection control signal, and the resistor selection control signal is generated by a software algorithm.

9. The electrical discharge constant current pulse power supply according to claim 1, characterized in that, The pulse power switching device is a MOS transistor, which is used to generate discharge pulses during the on period and pulse intervals during the off period to supply energy for pulse discharge between the electrode and the workpiece.

10. The electrical discharge constant current pulse power supply according to claim 1, characterized in that, The selection switch assembly includes a drive isolation unit for electrically isolating the control signal of the control module from the selection switch assembly, so as to drive the selection switch assembly to selectively engage or bypass the resistor branch.

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