Blind groove electric spark trepanning and reciprocating vibration multi-channel discharging combined machining method

Abstract

The invention discloses a blind groove electric spark trepanning and reciprocating vibration multi-channel discharging combined machining method, and belongs to the technical field of discharging machining. According to the method, firstly, a thin-wall electrode is adopted for conducting electric spark nesting machining on the outline of the large-depth blind groove, and a blank of the blind groove is efficiently drawn; and then reciprocating vibration multi-channel electric discharge machining is adopted to conduct efficient corrosion removal on the material core obtained after previous trepanning machining, and the corrosion removal efficiency and the surface quality are greatly improved through the synergistic effect of high-frequency reciprocating vibration of an electrode and multi-channel electric discharge. The interpolar chip removal, cooling and deionization characteristics in the machining process are improved, and the machining stability is maintained. Energy is dispersed to multiple channels through multi-channel discharge, the energy density of a single channel is reduced, electrode loss is reduced, and the surface quality is improved. The method is suitable for machining large-depth blind grooves with various end face sizes, the machining time is remarkably shortened, and the cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical discharge machining, and particularly to a combined machining method for blind groove electric discharge trepanning and reciprocating vibration multi-channel discharge. Background Technique

[0002] Difficult-to-machine materials, such as titanium alloys, superalloys, high-strength steels, and composite materials, which are new high-performance materials, are widely used in many fields such as aerospace, military weapons, and biomedicine due to their excellent properties. With the substantial improvement of equipment performance, the application demand for these materials will further increase, and structural parts will also develop towards complexity, thin-walledness, and integration. When machining these difficult-to-machine materials, traditional machining methods such as CNC milling expose problems such as large tool wear, high cost, and long machining cycle. In particular, problems such as low material removal rate and poor machining surface quality severely limit the accuracy and durability of parts. Therefore, it has gradually become an inevitable trend to adopt special machining methods to achieve high-efficiency, high-quality, and low-cost forming machining of difficult-to-machine materials.

[0003] Electric discharge trepanning machining only needs to erode the materials around the required machining shape on the workpiece without eroding all the materials inside the workpiece. Therefore, the electric discharge trepanning machining speed is faster, which can effectively shorten the machining cycle, reduce the tool electrode loss, and lower the machining cost. However, electric discharge trepanning machining can only machine through holes and cannot machine semi-closed structural parts such as blind holes and blind grooves.

[0004] Reciprocating vibration electrical discharge machining can ensure that the electrode and the workpiece are always in a relative motion state during the machining process, which can effectively eliminate the harm caused by arc discharge during the machining process. Moreover, the reciprocating vibration of the electrode can effectively discharge the erosion products generated between the electrodes, reducing abnormal discharge phenomena such as short circuits that occur as the machining depth increases. It has a stable and efficient machining effect for the erosion of thick materials. However, when machining deep grooves by reciprocating vibration electrical discharge machining, due to the reciprocating vibration of the electrode hitting the inner wall of the workpiece during the machining process, the machining efficiency of machining deep grooves is greatly reduced, increasing the production cycle of semi-closed structural parts such as blind holes and blind grooves.

[0005] Multi-channel discharge machining technology is a new type of special machining method established on the basis of traditional electro-discharge machining. That is, multiple resistors are connected in parallel in the discharge circuit to maintain the open-circuit voltage at each possible discharge channel formation point, realizing multi-channel discharge in one pulse and breaking through the technical barrier that only one discharge channel can be formed in one pulse in traditional discharge machining technology. The multi-channel group electrode can generate multiple discharge channels within a single pulse cycle. The current in each sub-electrode discharge branch is equal, and the current in the total discharge circuit is equal to the superposition of the currents in each unit sub-electrode discharge branches, rising in a stepped manner. The number of steps is the number of formed discharge channels. This method not only keeps the total discharge energy equal to that of traditional electro-discharge machining by dispersing the discharge energy, but also can effectively improve the surface quality of the workpiece.

[0006] When machining a deep blind groove using the traditional electro-discharge machining method, as the machining depth increases, the discharge environment between the electrodes will gradually deteriorate, and the flow rate of the working medium is slow, resulting in the inability to timely discharge the erosion products between the electrodes. In some cases, the erosion products even reattach to the substrate surface after being secondary discharged between the electrodes, seriously affecting the machining efficiency and the surface quality of the workpiece. Summary of the Invention

[0007] The object of the present invention is to provide a combined machining method of electro-discharge trepanning and reciprocating vibration multi-channel discharge for deep blind grooves, which can take into account machining efficiency and surface quality while ensuring continuous and stable machining. This method is applicable to machining deep blind grooves with various end-face sizes. Compared with the traditional machining method, it significantly shortens the machining time and reduces costs, providing a more advanced and reliable machining method for related industrial production.

[0008] To achieve the above object, the present invention provides the following technical solution: A combined machining method of electro-discharge trepanning and reciprocating vibration multi-channel discharge for blind grooves, comprising the following steps:

[0009] S1. First, clamp a thin-wall electrode on an electro-discharge machine tool and introduce a working medium into the thin-wall electrode.

[0010] S2. Carry out electro-discharge trepanning machining with a fixed depth on the contour part of the deep blind groove to be machined. During the machining process, cooperate with the tool-lifting instruction. After machining to the specified depth, lift the thin-wall electrode to machine a rectangular groove on the workpiece. This step can prevent the tool-collision phenomenon between the electrode side wall and the workpiece side wall during the subsequent reciprocating vibration multi-channel discharge machining process, and can improve the discharge stability of the machining area by enhancing the discharge between the electrodes.

[0011] S3. Replace it with a multi-channel electrode. The multi-channel electrode is composed of several resistors connected in parallel and respectively in series with sub-electrodes. Each sub-electrode includes a working medium inlet end and a discharge end. An insulating layer is provided on the outer wall of the sub-electrode to achieve multi-channel discharge machining. Introduce the working medium into the multi-channel electrode, and at the same time drive the reciprocating vibration device to make the multi-channel electrode generate a longitudinal feed superposed with a high-frequency lateral reciprocating motion, that is, on the basis of a single longitudinal feed motion, add a high-frequency lateral reciprocating motion.

[0012] S4. Perform reciprocating vibration multi-channel discharge machining on the previously machined rectangular groove until the core material in the rectangular groove is completely removed, that is, complete the machining of the large-depth blind groove.

[0013] Preferably, the wall thickness of the thin-walled electrode is in the range of 0.5 mm to 2 mm. A working medium inlet channel is provided at the top of the thin-walled electrode. The channel diameter is in the range of 5 mm to 10 mm, and the number of channels is at least one.

[0014] Preferably, the cross-sectional shape of the thin-walled electrode is an arbitrary rectangle and is set according to the shape of the cavity to be machined.

[0015] Preferably, the lateral reciprocating motion distance of the multi-channel electrode is in the range of 0.1 mm to 2 mm, and the lateral reciprocating vibration frequency is in the range of 10 times to 1500 times per minute.

[0016] Preferably, the materials of the thin-walled electrode and the multi-channel electrode include any conductive material.

[0017] Preferably, the resistance value range is 0.2 Ω to 50 Ω.

[0018] Preferably, the insulating layer is a polyurethane coating of 20 to 40 μm.

[0019] Preferably, during the machining process, keep the working medium flowing from the centers of the thin-walled electrode and the multi-channel electrode to the machining area, and the pressure range of the working medium is 0.01 MPA to 9 MPA.

[0020] Preferably, the working medium includes one or a combination of several of deionized water, spark oil, and working fluid, and the combination is configured in an equal volume ratio.

[0021] Preferably, the base material of the workpiece is any conductive material.

[0022] Compared with the prior art, the beneficial effects of the present invention:

[0023] 1. In the present invention, the wire EDM trepanning technology is adopted to erode the material of the surrounding contour of the cavity to be machined, so as to prevent the electrode from colliding with the cavity side wall driven by the reciprocating vibration device when the reciprocating vibration multi-channel EDM technology is subsequently used to erode the core material of the cavity. When the reciprocating vibration multi-channel EDM technology is subsequently used to erode the core of the cavity, since the reciprocating movement of the electrode during the machining process can change the flow state of the working medium and effectively discharge the erosion products from between the electrodes, it is ensured that the discharge instability phenomenon will not occur due to the increase of the machining depth during the subsequent machining process. Even if arc discharge occurs during the machining process, the mechanical arc breaking effect will be achieved due to the high-frequency reciprocating movement of the electrode.

[0024] 2. The present invention can continuously, stably and efficiently machine deep blind grooves compared with the traditional EDM. Compared with the EDM forming machining under the same electrical parameters, the machining efficiency is greatly improved and the machining stability is significantly enhanced. Especially when machining deep blind grooves of aerospace difficult-to-machine materials such as titanium alloy, superalloy, high-strength steel, etc., the present invention effectively solves the problems of low machining efficiency and poor surface quality, and provides a more advanced and reliable machining means for related industrial production.

[0025] 3. In the present invention, through the synergistic effect of the high-frequency reciprocating vibration of the electrode and multi-channel discharge, the energy is dispersed into multiple channels, the energy density of a single channel is reduced, the electrode loss is reduced, and the machining efficiency and surface quality of deep blind grooves are significantly improved. Moreover, the chip removal, cooling and deionization characteristics between the electrodes during the machining process are improved, and the machining stability is maintained. It has the characteristics of high efficiency and high quality machining for semi-closed structural parts such as blind holes and blind grooves, especially deep blind grooves. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, but do not constitute a limitation to the present invention.

[0027] In the drawings:

[0028] Figure 1 is a schematic diagram of the combined machining process of wire EDM trepanning and reciprocating vibration multi-channel EDM for the deep blind groove of the present invention;

[0029] Figure 2 is a schematic diagram of the structure of the reciprocating vibration multi-channel EDM machining device of the present invention;

[0030] The reference numerals in the figure: 1, workpiece; 2, thin-wall electrode; 3, working medium inflow channel; 4, core; 5, multi-channel electrode; 51, sub-electrode; 52, insulating layer; 53, resistor; 6, reciprocating vibration device; 7, pulse power supply; 8, working medium. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0032] Embodiment: As Figure 1 and Figure 2 shown, the present invention provides a combined machining method of electric discharge machining with a large-depth blind groove and reciprocating vibration multi-channel discharge, and the specific steps are as follows:

[0033] Preparation stage: Prepare workpiece 1, thin-walled electrode 2, working medium inflow channel 3, multi-channel electrode 5, sub-electrode 51, insulating layer 52, resistor 53, reciprocating vibration device 6, pulse power supply 7, and working medium 8;

[0034] Step 1: Clamp the thin-walled electrode 2 on an electric discharge machine tool, and introduce the working medium 8 into the thin-walled electrode 2;

[0035] Step 2: Perform electric discharge machining with a fixed depth on the contour part of the large-depth blind groove to be machined. During the machining process, cooperate with the tool lifting command. After machining to the specified depth, lift the thin-walled electrode 2 to machine a rectangular groove on the workpiece 1. This step can prevent the tool hitting phenomenon between the side wall of the electrode and the side wall of the workpiece during the subsequent reciprocating vibration multi-channel discharge machining process, and can improve the discharge stability of the machining area by enhancing the discharge stability during the subsequent machining process and discharging the erosion products between the electrodes;

[0036] Step 3: Replace it with the multi-channel electrode 5. The multi-channel electrode 5 is composed of several resistors 53 connected in parallel and respectively connected in series with the sub-electrodes 51. Each sub-electrode 51 has a working medium inflow end and a discharge end, and the outer wall of the sub-electrode has an insulating layer 52 to achieve multi-channel discharge machining. Introduce the working medium 8 into the multi-channel electrode 5, and at the same time drive the reciprocating vibration device 6 to make the multi-channel electrode 5 perform high-frequency transverse reciprocating motion on the basis of a single longitudinal feeding motion;

[0037] Step 4: Perform reciprocating vibration multi-channel discharge machining on the previously machined rectangular groove until the core 4 in the rectangular groove is completely removed, that is, the machining of the large-depth blind groove is completed.

[0038] Specifically, the wall thickness of the thin-walled electrode 2 is 1 mm, and there is a working medium inflow channel 3 at the top of the electrode, with a diameter of 10 mm.

[0039] Specifically, the transverse reciprocating motion distance of the multi-channel electrode 5 is 1 mm, and the frequency of the transverse reciprocating vibration is within the range of 1200 times per minute.

[0040] Specifically, the materials of the thin-walled electrode 2 and the multi-channel electrode 5 are copper.

[0041] Specifically, the resistance value of the resistor 53 is 0.2 Ω to 50 Ω.

[0042] Specifically, the insulating layer 52 is a polyurethane coating with a thickness of 20 to 40 μm.

[0043] Specifically, during the processing, the working medium 8 is always kept flowing continuously and stably from the centers of the thin-walled electrode 2 and the multi-channel electrode 5 to the processing area. Meanwhile, the pressure range of the working medium 8 is 2.5 MPA.

[0044] Specifically, the working medium 8 is deionized water.

[0045] Specifically, the base material of the workpiece 1 is titanium alloy (Ti-6Al-4V).

[0046] Working principle: The length, width, and height of the workpiece 1 are 60 mm, 50 mm, and 50 mm respectively, the length, width, and height of the blind groove to be machined are 40 mm, 40 mm, and 40 mm respectively, and the working medium 8 used during the processing is deionized water. First, the thin-walled electrode 2 is clamped on the electric discharge machine, and deionized water is introduced into the thin-walled electrode 2 to complete the tool setting between the thin-walled electrode 2 and the workpiece 1, as shown in Figure 1 Figure -a; Under the command of the spindle feed, electric discharge trepanning machining with a fixed depth is performed on the contour part of the blind groove to be machined, and the tool lifting command is coordinated during the processing, as shown in Figure 1 Figure -b; After machining to a depth of 40 mm, the thin-walled electrode 2 is lifted to machine a rectangular groove on the workpiece 1, as shown in Figure 1 Figure -c; Subsequently, the thin-walled electrode 2 is removed, the outer wall of the sub-electrode 51 is sprayed with the insulating layer 52, the resistor 53 is connected in series with the sub-electrode 51, all the sub-electrodes 51 are connected in parallel to form the multi-channel electrode 5, the multi-channel electrode 5 is clamped on the reciprocating vibration device 6, and deionized water is introduced into the top of the multi-channel electrode 5, as shown in Figure 2 Figure; The reciprocating vibration multi-channel discharge machining device is clamped on the machine, the end face of the multi-channel electrode 5 is aligned with the groove machined on the upper surface of the workpiece 1, the reciprocating vibration device 6 is driven to make the multi-channel electrode 5 perform reciprocating horizontal movement in the horizontal direction, as shown in Figure 1 Figure -d; Under the command of the spindle feed, reciprocating vibration multi-channel discharge machining is performed on the previously machined rectangular groove, as shown in Figure 1 Figure -e; During the processing until the core 4 in the rectangular groove is completely removed, the multi-channel electrode 5 is lifted, and the machining is completed, as shown in Figure 1 Figure -f.

[0047] This method can efficiently process deep blind grooves. By combining the reciprocating motion of the electrode to improve the inter-electrode state and the characteristics of multi-channel discharge to disperse the discharge energy, the deterioration of the inter-electrode discharge environment will not occur during the processing due to the increase in the processing depth. Even if arc discharge occurs, the high-frequency reciprocating motion of the electrode will play a role in mechanical arc breaking, thereby reducing the burns caused by abnormal discharge phenomena such as inter-electrode arcing and short-circuiting to the surface of the workpiece and the electrode, significantly improving the processing efficiency, surface quality and processing stability of the blind groove, and greatly reducing the electrode loss. At the same time, this method is simple to operate, convenient to implement and energy-saving. Especially when processing deep blind grooves of aviation difficult-to-machine materials such as titanium alloy, superalloy and high-strength steel, it has obvious advantages.

[0048] Finally, it should be noted that the above are only preferred examples of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A combined machining method of blind groove EDM trepanning and reciprocating vibration multi-channel discharge, characterized in that, It includes the following steps: S1. First, clamp the thin-walled electrode (2) on the electric discharge machine tool, and introduce the working medium (8) into the thin-walled electrode (2); S2. Perform fixed-depth electric discharge trepanning machining on the contour part of the workpiece (1) that needs to be machined with a large-depth blind groove. During the machining process, cooperate with the tool-lifting instruction. After machining to the specified depth, lift the thin-walled electrode (2) to machine a rectangular groove on the workpiece (1); S3. Replace it with a multi-channel electrode (5). The multi-channel electrode (5) is composed of several resistors (53) in parallel respectively connected in series with the sub-electrodes (51). Each sub-electrode (51) is provided with a working medium inlet end and a discharge end, and the outer wall of the sub-electrode is provided with an insulating layer (52) to achieve multi-channel discharge machining; while introducing the working medium (8) into the multi-channel electrode (5), drive the reciprocating vibration device (6) to make the multi-channel electrode (5) generate a longitudinal feed superimposed with a transverse high-frequency reciprocating motion; S4. Perform reciprocating vibration multi-channel discharge machining on the previously machined rectangular groove until the core material (4) in the rectangular groove is completely removed, that is, the machining of the large-depth blind groove is completed.

2. A blind groove electric discharge machining and reciprocating vibration multi-channel discharge combined machining method according to claim 1, characterized in that: The wall thickness of the thin-walled electrode is in the range of 0.5 mm to 2 mm. At least one working medium inlet channel (3) is provided at the top of the thin-walled electrode, and the channel diameter is in the range of 5 mm to 10 mm.

3. A combined machining method of blind groove EDM blanking and reciprocating vibration multi-channel discharge according to claim 1, characterized in that: The cross-sectional shape of the thin-walled electrode (2) is a rectangle matching the cavity to be machined.

4. A combined machining method of blind groove EDM blanking and reciprocating vibration multi-channel discharge according to claim 1, characterized in that: The transverse reciprocating motion stroke of the multi-channel electrode (5) is in the range of 0.1 mm to 2 mm, and the frequency of the transverse reciprocating vibration is in the range of 10 times to 1500 times per minute.

5. A combined machining method for blind groove EDM blanking and reciprocating vibration multi-channel discharge according to claim 1, characterized in that: The thin-walled electrode (2) and the multi-channel electrode (5) are made of any conductive material.

6. A combined machining method of blind groove electrical discharge trepanning and reciprocating vibration multi-channel discharge according to claim 1, characterized in that: The resistance value range of the resistor (53) is 0.2 Ω to 50 Ω.

7. A combined machining method for blind groove EDM blanking and reciprocating vibration multi-channel discharge according to claim 1, characterized in that: The insulating layer (52) is a polyurethane coating with a thickness of 20 to 40 μm.

8. A blind groove electric discharge machining and reciprocating vibration multi-channel discharge combined machining method according to claim 1, characterized in that: During the machining process, keep the working medium (8) flowing from the centers of the thin-walled electrode (2) and the multi-channel electrode (5) to the machining area, and the pressure range of the working medium (8) is 0.01 MPA to 9 MPA.

9. A combined machining method of blind groove electric discharge trepanning and reciprocating vibration multi-channel discharge according to claim 1, characterized in that: The working medium (8) includes one or a combination of deionized water, spark oil, and working fluid, and the combination is configured with an equal volume ratio.

10. A blind groove electric discharge trepanning and reciprocating vibration multi-channel discharge combined machining method according to claim 1, characterized in that: The base material of the workpiece (1) is any conductive material.

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