A green and efficient upward-looking electrospark machining method

Abstract

The present invention belongs to the field of special processing, and specifically, relates to an upward-looking green and efficient electrospark machining method. In the upward-looking green and efficient electrospark machining method, during the machining process, the tool electrode is located below the workpiece, and the tool electrode is servo-fed upward; a high-energy electrospark pulse power supply provides pulse energy to achieve efficient discharge erosion of the workpiece material, thereby achieving upward-looking green and efficient electrospark machining. The internal flow channel of the tool electrode continuously injects the working hydraulic pressure of deionized water mixed with fine bubbles into the working gap, takes the discharge erosion products away from the machining gap, and provides better discharge conditions. The monitoring module controls the electrode servo retraction in real time to prevent short-circuit burns. Compared with the existing electrospark machining method, the upward-looking green and efficient electrospark machining method according to the embodiment of the present invention can speed up the chip removal speed of the discharge machining process, obtain higher machining efficiency and better surface quality, and the machining advantage for ultra-deep hole groove structures is particularly significant.

Description

Technical Field

[0001] The invention belongs to the field of special processing, and in particular, relates to an upward-looking green and efficient electrospark processing method. Background Art

[0002] Traditional machining uses expensive tools made of cemented carbide and other materials, relying on mechanical cutting force to remove materials. Discharge machining technology often uses tool electrodes made of graphite, brass and other materials as "tools". It uses electric sparks or arc discharges to break through the working medium in the machining gap, and uses the formed plasma to thermally remove the workpiece material. The non-contact material removal method can ensure that the workpiece material is not affected by the strength and hardness of the workpiece material when machining, and has certain advantages when machining parts with complex structures. The commonly used tool materials for discharge machining are graphite, brass, etc., which are relatively cheap.

[0003] However, while EDM technologies, including arc machining technology, have advantages such as no cutting force and the ability to process complex structures, they still have the disadvantage of poor surface quality, and this phenomenon is particularly prominent when processing ultra-deep hole structures. At present, almost all EDM technologies use a top-down machining method in which the workpiece is at the bottom, the electrode is at the top, and the electrode is servo-fed downward to remove material. This is not conducive to the renewal of the working fluid in the machining gap, and may cause the EDM erosion products to fail to be discharged in time, thereby causing the discharge conditions to deteriorate, and short-circuit burns are prone to occur, resulting in poor surface quality. When EDM is used to manufacture blades for aerospace turbine disks and complex cavities for large molds, a large amount of raw materials need to be removed. However, when processing ultra-deep hole structures, the existing top-down EDM method has particularly serious electrode loss, and the cross-section of the hole presents an obvious inverted trapezoid with a wide top and a narrow bottom. The closer to the bottom of the hole, the smaller the machining gap, which is more unfavorable for the discharge of machining debris, and thus leads to deterioration of discharge conditions. Some researchers have invented an inverted machining method by combining electrochemistry and ultrasonic technology. Although this method has improved machining efficiency and surface quality to a certain extent, it still cannot meet the requirements of high-efficiency and high-quality machining. Therefore, an upward-looking green and efficient EDM method is urgently needed. Summary of the invention

[0004] In order to overcome the defects of the prior art, the present invention provides a green and efficient upward-looking electrospark machining method, which includes three steps:

[0005] Step 1: Install the tool electrode on the Z axis of the machine tool through a fixed chuck, and clamp the workpiece 2 on the workbench above the machine tool through a fixture. The tool electrode and the workpiece are respectively connected to the two poles of the output end of the high-energy electric spark pulse power supply; use a working fluid mixed with fine air bubbles as the working medium; adjust the tool electrode and the workpiece to the specified initial position, and set the machine tool processing program;

[0006] Step 2: Run the machining program described in step 1, the machine tool servo control system issues a motion command to control the Z-axis servo motor to drive the tool electrode to servo feed at a uniform speed from bottom to top; when the machining gap between the tool electrode and the workpiece reaches the discharge breakdown distance, the high-energy electric spark pulse power supply performs pulse discharge, and the plasma formed after the gap is broken down performs efficient thermal etching on the workpiece; at the same time, the working fluid is continuously injected into the machining gap through the internal flow channel of the tool electrode to take the discharge etching products away from the working gap; the monitoring system monitors the working voltage between the workpiece and the tool electrode in real time, and issues a retraction command when the machining voltage is lower than the set retraction voltage, and the Z-axis drives the tool electrode to move downward;

[0007] Step 3: When the monitoring system detects that the voltage between the tool electrode and the workpiece rises to the set working voltage again, it sends a signal, and the machine tool servo control system continues to run the unfinished processing program in step 2 until all processing programs are completed.

[0008] In the method, the working fluid mixed with fine air bubbles is prepared by uniformly mixing deionized water and compressed air through a venturi tube, wherein the inlet pressure of the deionized water is 0.1-0.4 MPa, and the inlet pressure of the compressed air is 0.2-0.8 MPa.

[0009] According to the method, a high-energy electric spark pulse power supply can efficiently remove workpiece materials through plasma in a machining gap; the output voltage range of the high-energy electric spark pulse power supply is 50-380 V, the output current range is 10-2000 A, the pulse width range is 1-20 ms, and the duty cycle range is 0.2-5.

[0010] In the method described, the fallback voltage set by the monitoring system is 70% of the working voltage of the high-energy electric spark pulse power supply.

[0011] Compared with the prior art, the effective gain effect of the present invention is: compared with the top-down discharge machining method, the top-down green and efficient electrospark machining method with the workpiece above and the electrode below can increase the working fluid pressure to a certain extent, and the participation of the high-energy electrospark pulse power supply can realize the efficient etching of the workpiece material. By detecting the work through the monitoring system to control the electrode retraction, the discharge medium in the working gap can be better updated, the etching products can be discharged more quickly, and the discharge conditions can be improved. Compared with other existing electrospark machining, it has higher machining efficiency and better surface quality, and the machining advantages for ultra-deep hole groove structures are particularly significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a working schematic diagram of a green and efficient EDM method looking up;

[0013] Figure 2It is a schematic diagram of the machining gap of a green and efficient EDM method viewed from above;

[0014] In the figure, 1. tool electrode, 2. workpiece, 3. deionized water, 4. fine air bubbles, 5. discharge etching products. DETAILED DESCRIPTION

[0015] The present invention is described in detail below with reference to specific embodiments in conjunction with the accompanying drawings. The embodiments provided herein are only used to explain the present invention but are not intended to limit the present invention.

[0016] like Figure 1 As shown, the present invention provides a green and efficient upward electrospark machining method, comprising three steps:

[0017] Step 1: Install the tool electrode 1 on the Z axis of the machine tool through a fixed chuck, and clamp the workpiece 2 on the workbench above the machine tool through a fixture. The tool electrode 1 and the workpiece 2 are respectively connected to the two poles of the output end of the high-energy electric spark pulse power supply; use a working fluid mixed with fine air bubbles 4 as the working medium; adjust the tool electrode 1 and the workpiece 2 to the specified initial position, and set the machine tool processing program;

[0018] Step 2: Run the machining program described in step 1, the machine tool servo control system issues a motion command to control the Z-axis servo motor to drive the tool electrode 1 to servo feed at a uniform speed from bottom to top; when the machining gap between the tool electrode 1 and the workpiece 2 reaches the discharge breakdown distance, the high-energy electric spark pulse power supply performs pulse discharge, and the plasma formed after the gap is broken down performs efficient thermal etching on the workpiece 2; at the same time, the working fluid is continuously injected into the machining gap through the internal flow channel of the tool electrode 1 to take the discharge etching product 5 away from the working gap; the monitoring system monitors the working voltage between the workpiece 2 and the tool electrode 1 in real time, and issues a retraction command when the machining voltage is lower than the set retraction voltage, and the Z-axis drives the tool electrode 1 to move downward;

[0019] Step 3: When the monitoring system detects that the voltage between the tool electrode 1 and the workpiece 2 rises to the set working voltage again, it sends a signal, and the machine tool servo control system continues to run the unfinished processing program in step 2 until all processing programs are completed.

[0020] Preferably, the working fluid mixed with fine air bubbles 4 is prepared by uniformly mixing deionized water 3 and compressed air through a venturi tube, wherein the inlet pressure of the deionized water 3 is 0.1-0.4 MPa, and the inlet pressure of the compressed air is 0.2-0.8 MPa.

[0021] Preferably, the high-energy electric spark pulse power supply efficiently etches the workpiece material through the plasma in the machining gap; the output voltage range of the high-energy electric spark pulse power supply is 50~380 V, the output current range is 10~2000 A, the pulse width range is 1~20 ms, and the duty cycle range is 0.2~5.

[0022] Preferably, the fallback voltage set by the monitoring system is 70% of the working voltage of the high-energy electric spark pulse power supply.

[0023] like Figure 2 As shown, during the process of electrical discharge machining, the working fluid mixed with fine air bubbles 4 is continuously injected into the machining gap through the flow channel inside the tool electrode 1. The green and efficient electrospark machining method has increased the injection pressure of the working fluid to a certain extent. The presence of fine air bubbles 4 effectively impacts the molten pool formed by the plasma on the surface of the workpiece 2, increases the amount of discharge etching products 5, and better entrains the discharge etching products 5, quickly taking them away from the working gap.

Claims

1. A green and efficient upward-looking electrospark machining method, characterized in that: There are three steps involved: Step 1: Install the tool electrode on the Z axis of the machine tool through the fixed chuck, and fix the workpiece on the workbench above the machine tool through the fixture. The tool electrode and the workpiece are respectively connected to the two poles of the output end of the high-energy electric spark pulse power supply; use the working fluid mixed with fine air bubbles as the working medium; adjust the tool electrode and the workpiece to the specified initial position, and set the machine tool processing program; Step 2: Run the machining program described in step 1, the machine tool servo control system issues a motion command to control the Z-axis servo motor to drive the tool electrode to servo feed at a uniform speed from bottom to top; when the machining gap between the tool electrode and the workpiece reaches the discharge breakdown distance, the high-energy electric spark pulse power supply performs pulse discharge, and the plasma formed after the gap is broken down performs efficient thermal etching on the workpiece; at the same time, the working fluid is continuously injected into the machining gap through the internal flow channel of the tool electrode to take the discharge etching products away from the working gap; the monitoring system monitors the working voltage between the workpiece and the tool electrode in real time, and issues a retraction command when the machining voltage is lower than the set retraction voltage, and the Z-axis drives the tool electrode to move downward; Step 3: When the monitoring system detects that the voltage between the tool electrode and the workpiece rises to the set working voltage again, it sends a signal, and the machine tool servo control system continues to run the unfinished processing program in step 2 until all processing programs are completed; The working fluid mixed with fine air bubbles is prepared by uniformly mixing deionized water and compressed air through a venturi tube, wherein the inlet pressure of deionized water is 0.1~0.4 MPa, and the inlet pressure of compressed air is 0.2~0.8 MPa; The high-energy electric spark pulse power supply can efficiently remove the workpiece material through the plasma in the machining gap; the output voltage range of the high-energy electric spark pulse power supply is 50~380 V, the output current range is 10~2000 A, the pulse width range is 1~20 ms, and the duty cycle range is 0.2~5; The fallback voltage set by the monitoring system is 70% of the working voltage of the high-energy spark pulse power supply.

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