CN-117381082-B - Electric spark pulse power supply current change rate control method

CN117381082BCN 117381082 BCN117381082 BCN 117381082BCN-117381082-B

Abstract

The invention provides a method for controlling the current change rate of an electric spark pulse power supply, which comprises a high-voltage breakdown loop for gap breakdown processing of electric spark processing, a constant-current source loop for controlling pulse discharge peak current and a current waveform control loop for controlling the current change rate of the front edge and the rear edge of an output current waveform. Different requirements in actual processing are met, and market applicability is better. The output current waveform can be effectively controlled to rise and fall with a certain slope, the variety of the output current waveform is increased, the processing efficiency is high, the electrode loss is low, and different processing requirements in actual production are met.

Inventors

SUN SHIWEI
CAO LIXIN
ZHANG JIAQIANG
WEI WANG
DENG DONGFENG
WANG HONGSHUANG
WANG PEIDE
WU DI
JIA JINGYU
LIU ZEKUN
HU QIAN
HU SU
XI SHANSHAN

Assignees

北京机床所精密机电有限公司

Dates

Publication Date: 20260505
Application Date: 20231103

Claims (8)

1. The electric spark pulse power supply is characterized by comprising a high-voltage breakdown loop for gap breakdown processing of electric spark processing, a constant current source loop for controlling pulse discharge peak current and a current waveform control loop for controlling the current change rate of the front edge and the rear edge of an output current waveform; The high-voltage breakdown loop comprises a direct-current second power supply V2, a first resistor R1, a second power switching tube Q2, a second resistor R2, a third diode D3 and a discharge gap, wherein the second power switching tube Q2 is connected with a processing time sequence controller; The constant current source loop comprises a constant current source charging loop and a constant current source follow current loop; The constant current source charging circuit comprises a direct current first power supply V1, a first power switch tube Q1, a current sensor, a first inductor L1 and a first diode D1, wherein the first power switch tube Q1 of the constant current source charging circuit is connected with a current closed-loop controller, and the current sensor is connected in series between the first power switch tube Q1 and the first inductor L1 of the constant current source charging circuit; When the first power switch tube Q1 is disconnected, the second power switch tube Q2 is disconnected, and the discharge gap is not broken down, the first inductor L1, the first diode D1, the direct-current second power supply V2 and the second diode D2 form a constant-current source freewheel loop; when the first power switch tube Q1 is opened, the second power switch tube Q2 is closed, and the discharge gap is broken down, the first inductor L1, the second power switch tube Q2, the second resistor R2, the inductor L, the third diode D3, the discharge gap and the second diode D2 which are connected in parallel form a constant current source freewheeling loop; The current waveform control loop is composed of at least more than two switches, at least more than two inductors, a second resistor R2, a third diode D3, a discharge gap and a fourth diode D4; The at least more than two switches and the at least more than two inductors are connected with the second resistor R2 in parallel; And the high-voltage breakdown loop circuit and the constant-current source loop form a discharge current loop when the gap is broken down, and the current waveform control loop controls the current change rate of the front edge and the rear edge of the output current waveform.
2. The spark pulse power supply of claim 1 wherein said constant current source circuit includes a low voltage constant current source circuit which is a low voltage current output circuit.
3. The spark pulse power supply according to claim 1, wherein the current waveform control loop is composed of a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a fifth switch S5, a sixth switch S6, a second inductor L2, a third inductor L3, a fourth inductor L4, a fifth inductor L5, a second resistor R2, a third diode D3, a discharge gap, and a fourth diode D4.
4. The spark pulse power supply according to claim 1, wherein the discharging current loop is composed of a direct current first power supply V1, a direct current second power supply V2, a first power switch tube Q1, a first inductor L1, a second power switch tube Q2, a second resistor R2, a third diode D3 and a discharging gap.
5. The spark pulse power supply according to claim 3, wherein the first power switch tube and the second power switch tube are any one of field effect transistors and insulated gate bipolar transistors.
6. An electric spark pulse power source as claimed in claim 5, characterized in that the switching control is selected to combine different inductance parameter loops.
7. The spark pulse power supply according to claim 1, wherein the control mode of the current closed-loop controller is a PWM control mode.
8. A current change rate control method using the spark pulse power source as described in any one of claims 1 to 7, characterized by comprising (1) Constant current source loop continuously stores energy before breakdown of discharge gap; (2) The high-voltage breakdown loop continuously boosts the breakdown discharge gap, the current closed-loop controller receives a detection signal of the breakdown of the discharge gap, and a target current value is set; (3) The closed loop of the second power switch tube is conducted, and the inductive current is output to the current waveform control loop; (4) The processing mode is selected by switching on and switching off the first switch S1; (5) The processing time sequence controller controls the pulse width and the pulse intermittence of the output current; (6) The current waveform control loop controls the current slope to rise or fall.

Description

Electric spark pulse power supply current change rate control method Technical Field The invention belongs to the technical field of electric spark machining power supplies, and particularly relates to a control method for the current change rate of an electric spark pulse power supply. Background Electric discharge machining is a non-contact special machining technique that creates a pulse energy between a tool electrode and a workpiece to remove the workpiece. With the advent of new materials, materials with excellent properties such as superalloys, but difficult to process, are widely used in aerospace, mold manufacturing, and other fields. Compared with the traditional machining, the electric spark machining can avoid a plurality of machining problems such as insufficient small-size deformation precision and the like caused by contact machining, and can also machine special metal materials such as high hardness, high strength, high melting point and the like and some precise parts with complex structures and shapes. The change of discharge energy of electric discharge machining is a key for determining machining efficiency and machining quality, and the control of the discharge energy mainly depends on the regulation and control of discharge current. The pulsed power supply is therefore particularly important for electrical discharge machining. Some traditional power supplies still applied today have low power efficiency because most of the energy consumption is consumed in the current limiting resistor. Along with the continuous improvement of requirements of energy conservation, environmental protection, high precision, high efficiency, low tool loss and the like of processed parts, the low energy consumption and the low tool loss performance of the pulse power supply are also required to be improved. The current waveform output by the spark pulse power supply in most processing application occasions is approximate to triangular wave or square wave. The literature shows that the rate of change of the leading and trailing edges of the output current waveform has a great influence on the loss of the electrodes. For difficult-to-process materials with high melting point, high hardness and the like, enough energy is needed to provide explosive force, the current front rises fast, and the slope is large. And some machining requiring low electrode loss and good surface quality require that the current leading edge output rise smoothly with a slightly smaller slope. But the energy cannot be too small, otherwise the processing time is increased, and the trailing edge of the current waveform cannot be too fast reduced, so that a certain pulse width is required to ensure a certain stable discharge. The special current waveform which is required to be output is combined with different processing conditions and requirements so as to meet different requirements. Patent document CN108422055B discloses a pulse power supply and a control method of the power supply current waveform, which remove the increase of the power utilization rate of the current limiting resistor of the traditional power supply, design the rising edge of the output current to rise to a certain extent, and increase the variety of the output current waveform, but the falling edge of the design current is unchanged and the current change rate of the rising edge is less. The current waveform output by the existing energy-saving pulse power supply is single, and the processing requirements of high performance are difficult to meet at the same time. Therefore, the problem of waveform control of the output current of the energy-saving power supply is one of important research directions in the field of electric spark machining. In view of the problems in the related art, no effective solution has been published in this field. Disclosure of Invention The invention provides an electric spark pulse power supply, which is improved in that the electric spark pulse power supply comprises a high-voltage breakdown loop for gap breakdown processing of electric spark processing, a constant current source loop for controlling pulse discharge peak current and a current waveform control loop for controlling the current change rate of the front edge and the rear edge of an output current waveform; The high-voltage breakdown loop comprises a direct-current second power supply V2, a first resistor R1, a second power switching tube Q2, a second resistor R2, a third diode D3 and a discharge gap, wherein the second power switching tube Q2 is connected with a processing time sequence controller; The constant current source loop comprises a constant current source charging loop and a constant current source follow current loop; The constant current source charging circuit comprises a direct current first power supply V1, a first power switch tube Q1, a current sensor, a first inductor L1 and a first diode D1, wherein the first power switch tube Q1 of the constant current