A cathode for electrochemical machining with a twisted channel and a machining method of cross-feed with a twisted channel

Abstract

A kind of cathode for electrochemical machining of twisted channels and a method for cross-feed machining of twisted channels provided by the present invention include a horizontal tool cathode, a vertical tool cathode and a power supply; in the present invention, the tool tip has a three-layer superposition structure of copper-tungsten alloy-stainless steel-copper-tungsten alloy, so that the tool tip does not need to be replaced frequently, reducing the production cost and ensuring the machining efficiency; at the same time, the auxiliary liquid in the hollow cavity of the tool body flows out from the narrow slit and converges with the main liquid outside, which helps to improve the stability of the flow field in the machining area and overcome the problem that the electrolytic products in the current electrochemical machining of twisted channels are not easy to discharge; in addition, the twisted channels are divided into two regions according to the morphological differences from the blade tip to the blade root, and the corresponding tool cathode contours are designed respectively, so that the machining accuracy and surface machining quality of the machined twisted channels can meet the machining requirements; finally, the horizontal tool cathode and the vertical tool cathode feed and machine simultaneously, shortening the machining time of the twisted channels and effectively improving the machining efficiency of the parts.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical machining equipment and machining methods, and particularly relates to a cathode for electrochemical machining of a twisted channel and a machining method for cross-feed machining of a twisted channel. Background Art

[0002] As key components in the aerospace field, integral components such as diffusers and blisks significantly improve key parameters such as the working efficiency and thrust-to-weight ratio of aeroengines. However, the twisted channel profiles between adjacent blades in blisks and diffusers are complex, and difficult-to-machine materials with excellent performance are widely used. At the same time, the machining accuracy and surface machining quality requirements for these twisted channels are very high, which makes the machining of twisted channels very difficult. Among them, electrochemical machining has become the main machining process for twisted channels on diffusers and blisks due to its advantages such as a wide range of machinable materials, no residual stress and heat-affected zone on the workpiece surface, high machining efficiency, and no tool wear. The electrochemical machining of twisted channels mainly includes two steps: pre-machining of the cascade channel and finish-machining of the blade profile. During the electrochemical machining of the cascade channel, most of the material is removed to form a cascade channel with a certain allowance on the workpiece blank. However, due to genetic errors, the allowance distribution of the blade blank will affect the subsequent electrochemical machining accuracy of the blade profile. Therefore, the pre-machining of the cascade channel plays a very crucial role in the electrochemical machining of twisted channels. However, the current electrochemical machining of twisted channels has the following problems:

[0003] (1) The machining edge material of the front end face of the tool cathode is stainless steel. If a short circuit occurs during the machining process, large areas of the front end face and machining edge of the tool cathode will be burned, and a new tool cathode needs to be replaced, which not only increases the production cost but also affects the machining efficiency. In addition, when electrochemically machining a twisted channel of titanium alloy, a large amount of flocculent insoluble substances will be generated in the machining area, which will adsorb on the surface of the tool cathode and affect the machining stability.

[0004] (2) As the complexity of the twisted channel increases, the morphological differences in the areas near the tip and root of the channel become larger and larger. The difference in the allowances between the blade suction surface and pressure surface in the twisted channel obtained by the current rotary feed electrochemical machining and the double-rotation electrochemical machining of the tool cathode and the workpiece is relatively large, and the maximum and minimum allowances are generally located at the tip and root of the cascade channel. Eventually, the machining accuracy and surface machining quality of the twisted channel cannot meet the machining requirements. At the same time, since components such as blisks and diffusers have multiple twisted channels, but the existing electrochemical machining only feeds radially through a single tool cathode, the machining of the twisted channel takes a long time and the production efficiency of the components is low. Summary of the Invention

[0005] In order to address the shortcomings and deficiencies of the prior art, a twisted channel electrolytic machining cathode and a twisted channel cross-feed machining method are provided, thereby solving the problems of high scrap rate in existing tool cathode manufacturing, increased production cost due to machining short circuit, low machining efficiency, and insufficient twisted channel machining accuracy and surface machining quality and long machining time caused by existing electrolytic machining methods.

[0006] A twisted channel electrolytic machining cathode provided to achieve the purpose of the present invention includes a horizontal tool cathode and a vertical tool cathode. The horizontal tool cathode and the vertical tool cathode are both connected to the negative electrode of a power supply through a wire, and the positive electrode of the power supply is connected to a workpiece blank through a wire. The horizontal tool cathode and the vertical tool cathode both include a cutter head, a blade body and a base. The cutter head is a three-layer stacked structure of copper-tungsten alloy-stainless steel-copper-tungsten alloy. The bottom of the cutter head is fixed to the top of the blade body through an axle pin, and the bottom of the blade body is fixed to the base through an axle pin. A hollow cavity is provided inside the blade body, and a plurality of narrow slits connected to the hollow cavity are provided on one side wall of the blade body, which are used to allow the auxiliary liquid in the hollow cavity to flow out from the narrow slits and merge with the main liquid outside.

[0007] As a further improvement of the above solution, the side profile of the blade body is polished by rough milling, electric spark finishing and ultrasonic electrochemical process to remove the surface recast layer.

[0008] A twisted channel cross-feed electrochemical machining method, characterized in that it includes the following steps:

[0009] Step 1, determine the processing area of the horizontal tool cathode and the vertical tool cathode;

[0010] Step 2, determining the feed speed of the horizontal tool cathode and the vertical tool cathode;

[0011] Step 3: The auxiliary liquid flows out from the narrow gap of the hollow cavity of the blade body and merges with the main liquid outside, and the electrolysis products are quickly discharged in the processing area. The horizontal tool cathode and the vertical tool cathode work together to process a twisted channel on the workpiece blank through electrochemical reaction.

[0012] As a further improvement of the above solution, the step 1 realizes the determination of the horizontal tool cathode and the vertical tool cathode processing area in the following manner:

[0013] Step 1.1, use a computer to simulate the contour of the twisted channel to be prepared to form a geometric model contour, and then divide the geometric model contour into n groups of control curves at equal intervals. i , the first group of control curves a1 and the nth group of control curves a n Vertically projected into a plane perpendicular to the rotation axis d, forming the first group of projection pairs b1 and the nth group of projection pairs b n, rotate the first set of projection pairs b1 by an angle θ around the rotation axis d to obtain the first set of rotated pairs c1, such that the contour of the first set of rotated pairs c1 is close to the contour of the nth set of projection pairs b n , then the rotation angle θ is the distortion angle of the geometric model contour, where i = 1, 2, 3... n, and n = 5, 6, 7...;

[0014] Step 1.2: Repeat the method of the above step S1.1 to obtain the distortion angle θ i between the first set of control curve pairs a1 and the ith set of control curve pairs a i , such that the distortion angle θ i between the first set of control curve pairs a1 and the ith set of control curve pairs a i is equal to half of the distortion angle θ of the geometric model contour obtained in step S1.1. Then, the area between the first set of control curve pairs a1 to the ith set of control curve pairs a i is the machining area of the horizontal tool cathode, and the remaining area is the machining area of the vertical tool cathode.

[0015] As a further improvement of the above solution, the horizontal tool cathode and the vertical tool cathode feed speeds v a , v b in step two are determined as follows:

[0016] Step 2.1: The feed speeds v a , v b of the horizontal tool cathode and the vertical tool cathode should be ensured to be 1.0 - 1.4 mm / min;

[0017] Step 2.2: The feed distance of the horizontal tool cathode is l a , the feed speed of the horizontal tool cathode is v a , the distance from the intake edge to the exhaust edge of the workpiece blank is b, and the feed speed of the vertical tool cathode is v b need to satisfy the following formula:

[0018] l a / v a > b / v b .

[0019] As a further improvement of the above solution, in step three, the horizontal tool cathode and the vertical tool cathode are driven simultaneously. The horizontal tool cathode feeds radially from the tool setting position and returns to the tool setting position after the machining is completed. The vertical tool cathode feeds axially from the tool setting position. After penetrating the channel machined by the horizontal tool cathode, it returns to the tool setting position, thereby realizing the coordinated linkage of the horizontal tool cathode and the vertical tool cathode.

[0020] The beneficial effects of the present invention are:

[0021] Compared with the prior art, a cathode for electrolytic machining of a twisted channel and a machining method of cross-feed of the twisted channel provided by the present invention have the following advantages:

[0022] 1. In the present invention, the tool tips of the horizontal tool cathode and the vertical tool cathode are of a three-layer stacked structure of copper-tungsten alloy-stainless steel-copper-tungsten alloy. In the machining process, if a short circuit occurs, the damage to the machining surface of the tool tip is small, so that the tool tip does not need to be frequently replaced, reducing the production cost while ensuring the machining efficiency; at the same time, the tool tips, tool bodies and bases in the horizontal tool cathode and the vertical tool cathode are fixedly connected by pin shafts. When the morphologies of the machined twisted channels are different, the tool tips, tool bodies and bases can be replaced extremely conveniently; in addition, the side profiles of the horizontal tool cathode and the vertical tool cathode replace the original precision milling machining method with the electro-discharge forming machining method in the machining process, thus avoiding the deformation caused by the precision milling machining method, and then removing the surface recast layer by ultrasonic electro-chemical polishing, improving the qualified rate of finished products and the surface machining quality; finally, a hollow cavity and a narrow slit are arranged in the horizontal tool cathode and the vertical tool cathode, and the auxiliary liquid in the hollow cavity flows out from the narrow slit and converges with the main liquid outside, which helps to improve the stability of the flow field in the machining area and overcome the problem that the electrolytic products in the current electrolytic machining of the twisted channel are not easily discharged.

[0023] 2. In the present invention, the twisted channel is divided into two regions according to the morphological differences from the blade tip to the blade root, and the corresponding tool cathode profiles are designed for the two regions respectively, so that the difference in the allowance of the machined twisted channel is reduced, and the machining accuracy and the surface machining quality of the twisted channel can meet the machining requirements; at the same time, the horizontal tool cathode and the vertical tool cathode feed and machine the workpiece blank at the same time, so that the machining time of the twisted channel is shortened, effectively improving the machining efficiency of the parts. Description of the Drawings

[0024] Figure 1 is a schematic diagram of the cathode for electrolytic machining of the twisted channel in the present invention;

[0025] Figure 2 is a schematic diagram of the structures of the horizontal tool cathode and the vertical tool cathode in the present invention;

[0026] Figure 3 is a schematic diagram of the morphology of the workpiece blank in the electrolytic machining process in the present invention;

[0027] Figure 4 is a schematic diagram of equally spacing the geometric model contour to divide out the control curve pairs in the present invention;

[0028] Figure 5 is a process schematic diagram of Step 1 in the present invention.

[0029] Among them, 1 - cutting head; 2 - tool body; 3 - base; 4 - hollow cavity; 5 - narrow slit; 6 - power supply; 7 - workpiece blank; 8 - horizontal tool cathode; 9 - vertical tool cathode; 71 - blade tip; 72 - inlet edge; 73 - blade root; 74 - exhaust edge; 75 - geometric model; a i - the i-th group of control curve pairs; b i - the i-th group of projection pairs; c i - the i-th group of rotation pairs; d - rotation axis. Specific embodiments

[0030] The following further elaborates on the specific embodiments of the present invention in conjunction with the accompanying drawings:

[0031] Embodiment 1

[0032] As Figure 1 - Figure 2 shown, the present invention provides a twisted channel electrochemical machining cathode, including a horizontal tool cathode 8 and a vertical tool cathode 9. The horizontal tool cathode 8 and the vertical tool cathode 9 are both connected to the negative electrode of the power supply 6 through wires, and the positive electrode of the power supply 6 is connected to the workpiece blank 7 through a wire.

[0033] Both the horizontal tool cathode 8 and the vertical tool cathode 9 include a cutting head 1, a tool body 2, and a base 3. The cutting head 1 is a three-layer stacked structure of copper-tungsten alloy - stainless steel - copper-tungsten alloy, obtained by the rolling composite method. The thickness of the copper-tungsten alloy layers on both sides is about 0.1 mm, and the thickness of the middle stainless steel layer depends on the width of the narrowest part of the geometric model profile 75 formed by simulating the profile of the twisted channel to be prepared by computer. The horizontal tool cathode 8 forms three machining surfaces on the workpiece blank 7, and its profile is designed according to the curves of the blade tip 71 and the blade root 73 in the geometric model profile 75 formed by simulating the profile of the twisted channel by computer; the vertical tool cathode 9 forms five machining surfaces on the workpiece blank 7, and its profile is designed according to the curves of the inlet edge 72 and the exhaust edge 74 in the geometric model profile 75 formed by simulating the profile of the twisted channel by computer.

[0034] The bottom of the cutting head 1 is fixed to the top of the tool body 2 through a pin, the bottom of the tool body 2 is fixed to the base 3 through a pin, a hollow cavity 4 is opened inside the tool body 2, and a plurality of narrow slits 5 communicating with the hollow cavity 4 are opened on one side wall of the tool body 2 for flowing the auxiliary liquid in the hollow cavity 4 out of the narrow slits 5 to converge with the main liquid outside to occur an electrolytic reaction. The side profile of the tool body 2 is polished by rough milling, electrical discharge finishing, and ultrasonic electrochemical process to remove the surface recast layer.

[0035] As Figure 3 - Figure 5 shown, the present invention provides a twisted channel cross-feed electrochemical machining method, including the following steps:

[0036] Step 1. Determine the machining areas of the horizontal tool cathode 8 and the vertical tool cathode 9;

[0037] Among them, the determination of the machining areas of the horizontal tool cathode 8 and the vertical tool cathode 9 in Step 1 is achieved through the following method:

[0038] Step 1.1. Use a computer to simulate and form the geometric model profile 75 of the distorted channel profile to be fabricated, and then divide the geometric model profile 75 into n groups of control curve pairs a at equal intervals i , project the first group of control curve pairs a1 and the nth group of control curve pairs a n vertically onto a plane perpendicular to the rotation axis d to form the first group of projection pairs b1 and the nth group of projection pairs b n , rotate the first group of projection pairs b1 by an angle θ around the rotation axis d to obtain the first group of rotation pairs c1, such that the profile of the first group of rotation pairs c1 is close to the profile of the nth group of projection pairs b n , then the rotation angle θ is the distortion angle of the geometric model profile 75, where i = 1, 2, 3... n, and n = 5, 6, 7...;

[0039] Step 1.2. Repeat the method in Step S1.1 to obtain the distortion angle θ i between the first group of control curve pairs a1 and the ith group of control curve pairs a i , such that the distortion angle θ i between the first group of control curve pairs a1 and the ith group of control curve pairs a i is equal to half of the distortion angle θ of the geometric model profile 75 obtained in Step S1.1. Then, the area between the first group of control curve pairs a1 and the ith group of control curve pairs a i is the machining area of the horizontal tool cathode 8, and the remaining area is the machining area of the vertical tool cathode 9.

[0040] Step 2. Determine the feed rates of the horizontal tool cathode 8 and the vertical tool cathode 9;

[0041] Among them, the determination of the feed rates v a , v b of the horizontal tool cathode 8 and the vertical tool cathode 9 in Step 2 is achieved through the following method:

[0042] Step 2.1. To avoid short - circuit phenomena during machining, the feed rates v a , v b of the horizontal tool cathode 8 and the vertical tool cathode 9 should be ensured to be within 1.0 - 1.4 mm / min;

[0043] Step 2.2. The feed distance of the horizontal tool cathode 8 is l a , and the feed rate of the horizontal tool cathode 8 is v a, the distance from the air intake edge 72 to the exhaust edge 74 of the workpiece blank 7 is b and the feed speed of the vertical tool cathode 9 is v b The following formula must be satisfied:

[0044] l a / v a >b / v b .

[0045] That is, the vertical tool cathode 9 is processed first, and the horizontal tool cathode 8 is processed subsequently, and finally a through twisted channel is formed.

[0046] Step 3: The auxiliary liquid flows out from the hollow cavity 4 of the blade body 2 through the narrow slit 5 and merges with the main liquid outside, and the electrolysis product is quickly discharged in the processing area. The horizontal tool cathode 8 and the vertical tool cathode 9 work together to process a twisted channel on the workpiece blank through electrochemical reaction.

[0047] In step three, the horizontal tool cathode 8 and the vertical tool cathode 9 are driven simultaneously. The horizontal tool cathode 8 is radially fed from the tool setting position and returns to the tool setting position after the processing is completed. The vertical tool cathode 9 is axially fed from the tool setting position and returns to the tool setting position after the channel processed by the horizontal tool cathode 8 is connected, thereby realizing the coordinated linkage of the horizontal tool cathode 8 and the vertical tool cathode 9.

[0048] In addition, the electrolyte parameters (electrolyte concentration, temperature, etc.) and electrical machining parameters (machining voltage, pulse frequency) are related to the electrochemical dissolution characteristics of the processed materials. Taking the high-temperature alloy GH4169 as an example, the processing voltage is 20V, the electrolyte is sodium nitrate, the concentration is 20%, the pressure is 0.70Mpa, the temperature is 30°C, etc.

[0049] During the processing of the twisted channel, the auxiliary liquid in the hollow cavity 4 of the blade body 2 flows out through the narrow slit 5 and merges with the main liquid flowing into the liquid inlet of the electrolytic machining fixture, and the electrolysis product is quickly discharged in the processing area.

[0050] The above embodiments are not limited to the technical solutions of the embodiments themselves, and the embodiments can be combined with each other to form new embodiments. The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Any modification or equivalent replacement that does not deviate from the spirit and scope of the present invention shall be included in the scope of the technical solutions of the present invention.

Claims

1. A cathode for electrochemical machining with a twisted channel, characterized in that: The invention comprises a horizontal tool cathode (8) and a vertical tool cathode (9), wherein the horizontal tool cathode (8) and the vertical tool cathode (9) are both connected to the negative electrode of a power source (6) via a wire, and the positive electrode of the power source (6) is connected to a workpiece blank (7) via a wire. The horizontal tool cathode (8) and the vertical tool cathode (9) both comprise a cutter head (1), a cutter body (2) and a base (3). The cutter head (1) is a three-layer stacked structure of copper-tungsten alloy-stainless steel-copper-tungsten alloy. The bottom of the cutter head (1) is fixed to the top of the cutter body (2) via an axle pin, and the bottom of the cutter body (2) is fixed to the base (3) via an axle pin. A hollow cavity (4) is provided inside the cutter body (2), and a plurality of narrow slits (5) connected to the hollow cavity (4) are provided on a side wall of the cutter body (2), for allowing auxiliary liquid in the hollow cavity (4) to flow out from the narrow slits (5) to merge with external main liquid.

2. The twisted-channel electrochemical machining cathode according to claim 1, wherein: The side profile of the blade body (2) is rough milled, electrospark finished and polished using an ultrasonic electrochemical process to remove the surface recast layer.

3. The cross-feed electrochemical machining method for a twisted-channel electrochemical machining cathode according to any one of claims 1-2, characterized in that: The following steps are included: Step 1, determining the processing area of the horizontal tool cathode (8) and the vertical tool cathode (9); Step 2, determining the feed speed of the horizontal tool cathode (8) and the vertical tool cathode (9); Step 3: The auxiliary liquid flows out from the hollow cavity (4) of the blade (2) through the narrow slit (5) to merge with the main liquid outside, and the electrolysis product is quickly discharged in the processing area. The horizontal tool cathode (8) and the vertical tool cathode (9) work together to process a twisted channel on the workpiece blank through an electrochemical reaction.

4. A method for electrolytic machining of a twisted channel with cross-feed according to claim 3, characterized in that: The step 1 is implemented by determining the processing area of the horizontal tool cathode (8) and the vertical tool cathode (9) in the following manner: Step 1.1: Use a computer to simulate and form a geometric model contour (75) of the twisted channel profile to be fabricated, and then equally divide the geometric model contour (75) into n groups of control curve pairs a i , project the first group of control curve pairs a1 and the nth group of control curve pairs a n vertically onto a plane perpendicular to the rotation axis d to form the first group of projection pairs b1 and the nth group of projection pairs b n , rotate the first group of projection pairs b1 by an angle θ around the rotation axis d to obtain the first group of rotation pairs c1, such that the contour of the first group of rotation pairs c1 is close to the contour of the nth group of projection pairs b n , then the rotation angle θ is the twist angle of the geometric model contour (75), where i = 1, 2, 3... n and n = 5, 6, 7...; Step 1.2: Repeat the method of step 1.1 to obtain the first group of control curve pairs a1 and the i-th group of control curve pairs a i The twist angle θ i , so that the first group of control curves a1 and the i-th group of control curves a i The twist angle θ i The value of is equal to half of the twist angle θ of the geometric model contour (75) obtained in step 1.1, then the first group of control curves a1 to the i-th group of control curves a i The area in between is the processing area of the horizontal tool cathode (8), and the remaining area is the processing area of the vertical tool cathode (9).

5. A method for electrolytic machining of a twisted channel cross-feed according to claim 3, characterized in that: The second step realizes the determination of the feeding speeds v a and v b of the horizontal tool cathode (8) and the vertical tool cathode (9) in the following manner: Step 2.1, the feed rates v a and v b of the horizontal tool cathode (8) and the vertical tool cathode (9) should be ensured to be 1.0 - 1.4 mm / min; Step 2.2, the feeding distance of the horizontal tool cathode (8) is l a , the feeding speed of the horizontal tool cathode (8) is v a , the distance from the intake edge (72) to the exhaust edge (74) of the workpiece blank (7) is b and the feeding speed of the vertical tool cathode (9) is v b The following formula needs to be satisfied: l a / v a > b / v b .

6. A method for electrolytic machining with a twisted channel cross-feed according to claim 3, characterized in that: In the step three, the horizontal tool cathode (8) and the vertical tool cathode (9) are driven simultaneously, the horizontal tool cathode (8) is radially fed from the tool setting position, and returns to the tool setting position after the processing is completed, and the vertical tool cathode (9) is axially fed from the tool setting position, and returns to the tool setting position after the channel processed by the horizontal tool cathode (8) is connected, thereby realizing the coordinated linkage of the horizontal tool cathode (8) and the vertical tool cathode (9).

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