Combined seam electrode electrolytic milling tool and method

Abstract

The invention relates to a combined type seam electrode electrolytic milling tool and method, and belongs to the field of electrolytic machining. The combined tool provided by the invention comprises an electrode supporting plate, a cathode block, an insulating cover plate and an insulating sleeve shell. The pair of cathode block units are positioned and installed on the electrode supporting plate, the peripheries of the cathode block units are wrapped by the insulating sleeve shell and the insulating cover plate, only the central liquid outlet seam is exposed, an electric field is limited from diffusing outwards from the end face and the outer contour face of the cathode block, electricity is supplied more intensively only through the inner contour face of the cathode block, and the anode current density is greatly improved; and the processing precision and the processing locality are obviously improved while the stray corrosion is reduced. The combined structure solves the problem that an extremely narrow liquid outlet seam is difficult to manufacture, a flow channel between opposite inner contour surfaces of the cathode block is narrowed, an electric field is further concentrated, electrolyte jet flow is sprayed out in an accelerated mode after being compressed, machining products are washed in an accelerated mode, the high conductivity of electrolyte in the machining gap is guaranteed, and continuous and efficient electrolysis is promoted. And the electrolytic milling surface quality and the machining efficiency are effectively improved.

Description

Technical Field

[0001] The present invention relates to a combined slit electrode electro-chemical milling tool and method, belonging to the field of electro-chemical machining. Background Art

[0002] Electro-chemical milling is a non-contact machining method for removing materials based on the principle of electro-chemical anodic dissolution. It uses a numerical control system to control the tool electrode to move along a predetermined path on the workpiece surface. Meanwhile, the electrolyte flows in the gap between the electrode and the workpiece. When the current is switched on, the metal of the workpiece undergoes oxidative dissolution, thereby achieving efficient machining of difficult-to-cut materials. Compared with traditional mechanical milling, during electro-chemical milling, materials are removed layer by layer in the form of ions, avoiding thermal deformation and mechanical stress, and being suitable for thin-walled parts or precision components. Moreover, since there is no physical contact between the electrode and the workpiece, tool wear in traditional milling is avoided. Therefore, electro-chemical milling is not restricted by the hardness, strength, and toughness of the anode material and is very suitable for batch machining of difficult-to-cut materials and complex structural parts. Electro-chemical milling not only has good machining flexibility and wide adaptability, but also has low tool cost, short design and manufacturing cycle, and can ensure the stability and consistency of the machining process. Therefore, electro-chemical milling has been widely applied in fields such as medical treatment, automotive, and aerospace.

[0003] During the electro-chemical milling process, the commonly used rectangular electrode has uneven electric field distribution because the electric field intensity distribution on the bottom surface of the electrode is affected by factors such as electrode shape, machining gap, and electrolyte flow field. At the sharp corners of the liquid outlet holes of the rectangular electrode, the current density is the most concentrated and the local material removal is the strongest; while the current density from the bottom surface to the side wall of the rectangular electrode gradually decreases, increasing the surface roughness and shape error of the machining surface and deteriorating the machining surface quality. For example, in the machining of deep and narrow grooves of molds, it is difficult for traditional electro-chemical machining to control the side wall taper, resulting in insufficient precision and affecting the mold life or part fit. In addition, the right-angle structure of the rectangular electrode is prone to forming eddy currents or dead zones in the machining gap, hindering the electrolyte from timely carrying away reaction products (such as metal hydroxides, bubbles, etc.). The residual products will reduce the conductivity of the local electrolyte, leading to abnormal current distribution and affecting machining precision and efficiency. Moreover, the exposed side walls of the rectangular electrode will produce an edge electric field diffusion effect, generating a low current density area on the anode surface, causing secondary corrosion of the machined area and stray corrosion of the machined contour, damaging the machining localization, machining precision, and machining surface quality.

[0004] In terms of flow field, the right angle or sudden change cross section of the traditional rectangular electrode flow channel is easy to cause turbulence, increase flow resistance, and make it difficult for the electrolytic products to be taken away by the electrolyte in time. They are deposited in the low flow rate area, blocking the flow channel and further deteriorating the uniformity of the flow field. At the same time, too low electrolyte flow rate will also cause concentration polarization in the processing gap, which is not conducive to maintaining the high conductivity of the electrolyte in the processing gap and the stability of the processing electric field. Therefore, the flow field and electric field design are very attractive for achieving precise and efficient electrolytic milling.

[0005] Now more and more scholars are engaged in the optimization design of electric field and flow field in electrolytic milling. In terms of flow field, in addition to simply increasing the power of the water pump to increase the flow rate, some scholars have proposed to adjust the flow channel by chamfering the edge to reduce the flow resistance. The patent "Process method for electrolytic milling with extremely small machining gap by reverse copying electrode" (CN116197471A) is to trim the sharp right angle at the bottom of the rectangular electrode by reverse copying with reverse polarity. Some scholars have proposed to adjust the back pressure to increase the pressure difference between the inlet and outlet liquids. The patent "A cathode and electrolytic processing device for electrolytic milling" (CN118752016A) is to recover the electrolyte flowing out of the machining gap by setting a negative pressure reflux port, increase the electrolyte discharge speed, and take away the processing products in time. However, this method requires the additional installation of a negative pressure device, which not only increases the cost, but also is only suitable for cut-in processing, which has certain requirements for the machining gap and is not widely applicable. Some scholars have also proposed to compress the flow channel, but the rectangular electrode outlet hole is a long and thin flat hole, and its narrowing is severely limited by the manufacturing level.

[0006] In terms of electric field, some scholars have optimized the electrode shape by using arc edges, end face tilting and other forms to reduce the impact of edge effects and improve the electric field distribution. The patent "Process method for electrolytic milling with extremely small machining gap by reverse copying electrodes" (CN116197471A) is to trim the sharp right angles of rectangular electrodes into smooth rounded corners by reverse copying with reverse polarity to eliminate the concentrated area of ​​current density distribution. This method is simple and efficient, but it still cannot eradicate stray corrosion. Some scholars have also introduced auxiliary electric fields to adjust the current density distribution, thereby improving the uniformity of the electric field in the processing area. The patent "Electrolytic processing device and method for special-shaped holes that actively suppress stray corrosion" (CN107999907A) combs the stray electric field through a low-voltage controllable electric field to suppress stray corrosion. Although the effect is obvious, this method increases the complexity and cost of the system, and the installation and adjustment of the auxiliary electrode are relatively cumbersome. In summary, it is urgent to find a simple structure, convenient installation, and low-cost way to constrain the electric field and improve the flow field distribution to achieve precise and efficient electrolytic milling. Summary of the invention

[0007] In view of the problems existing in the above-mentioned prior art, the present invention designs a combined slit electrode electrochemical milling tool and method, aiming to realize the constraint of the electric field with a simple device, supply electric quantity concentratedly by the inner contour surface of the tool electrode, improve the machining current density and machining accuracy; at the same time, the problem of difficult machining of the extremely narrow electrolyte flow channel of the rectangular electrode is solved through the combined design, which not only greatly reduces the cost, but also accelerates the flow rate of the electrolyte in the machining gap, ensures the high cleanliness and high conductivity of the electrolyte in the machining gap, and improves the machining efficiency and machining surface quality of electrochemical milling.

[0008] A combined slit electrode electrochemical milling tool, characterized in that it comprises an electrode support plate, a cathode block, an insulating cover plate and an insulating sleeve; The above-mentioned electrode support plate is a metal plate, and a rectangular hole is opened in the center thereof; The above-mentioned cathode block is composed of a left cathode block unit and a right cathode block unit; the left cathode block unit and the right cathode block unit are arranged symmetrically left and right, and an electrolyte flow channel is formed between their opposite inner contour surfaces; the left cathode block unit and the right cathode block unit are successively divided into a tail part, a middle part and a head part from top to bottom; the tail parts of the left and right cathode block units are jointly inserted into the rectangular hole of the electrode support plate for positioning, and the distance between the two tail parts gradually narrows from top to bottom; the distance between the middle parts of the left and right cathode block units and the distance between the head parts are both the same as the narrowest distance at the bottom between the two tail parts; the heads of the left cathode block unit and the right cathode block unit are both triangular, that is, the cross-section of the head gradually decreases from top to bottom and finally forms an edge line; the edge lines formed by the heads of the left and right cathode block units form the cathode block liquid outlet slit; The above-mentioned insulating sleeve and insulating cover plate are successively divided into a body part and a head part from top to bottom; the insulating sleeve and insulating cover plate are both fixed to the electrode support plate through the body part; the insulating sleeve is located at the rear side of the left cathode block unit and the right cathode block unit, and the inner contours of its body part and head part match the outer contours of the middle part and head part of the cathode block, so that the rear side, left side, right side and lower side of the cathode block are all covered and protected therein; the insulating cover plate is located at the front side of the cathode block to protect the front side of the cathode block by fitting; An insulating sleeve liquid outlet slit is provided at the position where the head of the above-mentioned insulating sleeve coincides with the cathode block liquid outlet slit; the outer contours of the heads of the insulating sleeve and the insulating cover plate are both frustum structures with a gradually decreasing cross-section from top to bottom, and gradually shrink to the insulating sleeve liquid outlet slit to avoid the influence of the end face on the machining.

[0009] Therefore, in the combined slit electrode electrochemical milling tool, the left-right direction of the electrolyte flow channel is restricted by the left and right cathode block units, and the front-back direction is restricted by the insulating cover plate and the insulating housing. The tails of the left and right cathode block units are jointly inserted into the rectangular holes of the electrode support plate for positioning. The cathode blocks can be positioned in two directions by means of the inner walls of the rectangular holes in two perpendicular directions. The rectangular holes thus become the inlets of the electrolyte flow channels. The distance between the two tails of the left and right cathode block units gradually narrows from top to bottom. In this way, there is a transition during the process of the electrolyte flowing from the large rectangular hole at the top to the extremely narrow flow channel between the relatively inner contour surfaces of the two cathode block units at the bottom. The electrolyte can be smoothly and gradually compressed, avoiding chaotic turbulence caused by sudden changes in the flow channel size. Therefore, the electrolyte flow channel is divided into upper and lower parts. The upper part can be called the transition section of the electrolyte flow channel. In the lower part of the electrolyte flow channel, the distances between the middle parts and the head parts of the left and right cathode block units are the same as the narrowest distance at the bottom between the two tails, which can be called the extremely narrow section of the electrolyte flow channel. The function of this section of the flow channel is to constrain the electrolyte compressed and accelerated through the transition section into a laminar flow with a vertically downward flow direction. The cross-section of the heads of the left and right cathode block units gradually decreases from top to bottom until a ridge line is formed. The cathode block liquid outlet slit is between the two ridge lines. The cathode block liquid outlet slit is the lowest end of the extremely narrow flow channel. The liquid outlet slit of the insulating housing coincides with the cathode block liquid outlet slit. They are the lowest ends of the entire combined slit electrode electrochemical milling tool. The electrolyte sprays out from the liquid outlet slit of the insulating housing onto the workpiece surface to participate in the electrolysis process, and then scatters and discharges the electrolysis products. In order to reduce the obstruction of the too small machining gap between the lowermost end faces of the insulating housing and the insulating cover plate and the workpiece surface to the discharge of the products, the heads of their frustum structures contract the lowermost end faces as small as possible.

[0010] The cross-section of the heads of the left and right cathode block units gradually decreases from top to bottom until a ridge line is formed. The cathode block liquid outlet slit is formed between the two ridge lines, which also means that the lowermost end face and the side face of the cathode block are integrated, or rather, the lowermost end face of the cathode block no longer exists, which has never occurred in the cathode design of traditional electrochemical milling tools in the past. In addition, the insulating housing and the insulating cover plate fit and protect the rear side, left side, right side, lower side, and front side of the cathode block. The liquid outlet slit of the insulating housing at the head of the insulating housing coincides with the cathode block liquid outlet slit. In this way, only the inner contour surfaces of the lowermost heads of the left and right cathode block units of the entire cathode block can provide an electric field and supply electricity through the liquid outlet slit of the insulating housing.

[0011] The electrochemical milling method using the above-mentioned combined slit electrode electrochemical milling tool is characterized by including the following processes: The electrode support plate is connected to the negative pole of the power supply and clamped on the machine tool spindle, and the workpiece is connected to the positive pole of the power supply; The electrolyte flows into the rectangular hole in the center of the electrode support plate through the spindle, passes through the flow channel between the relatively inner contour surfaces of the two cathode block units, and then sprays out from the liquid outlet slit of the insulating housing onto the machining area of the workpiece; During machining, the electrode support plate, the cathode block, and the workpiece are energized. Under the electrolytic action, the workpiece material directly below the liquid outlet slit of the insulating jacket dissolves and generates a large number of insoluble electrolytic product particles. During the process that the electrolyte enters the gap between the opposing inner contour surfaces of the two cathode block units from the rectangular hole in the center of the electrode support plate, the flow channel is narrowed and compressed, accelerating the ejection from the liquid outlet slit of the insulating jacket, quickly flushing away the heat and products generated during machining, ensuring high cleanliness and high conductivity of the electrolyte in the machining gap, promoting the continuous and efficient progress of the electrolytic action, and effectively improving the surface quality and machining efficiency of electrolytic milling. In addition, the two cathode block units are wrapped by the insulating cover plate and the insulating jacket, preventing the electric field from diffusing outward from the end face and the outer contour surface. The electric quantity is only supplied centrally through the inner contour surface, greatly increasing the anode current density, reducing stray corrosion, and significantly improving the machining accuracy and machining localization at the same time.

[0012] The electrolytic action occurs in the machining gap directly below the liquid outlet slit of the insulating jacket. The electrolyte accelerates and ejects from the liquid outlet slit of the insulating jacket. When discharging, there is no obstruction from the lowermost end faces of the insulating jacket and the insulating cover plate, so that the electrolyte in the machining gap can be quickly circulated and updated, ensuring high cleanliness and high conductivity of the electrolyte in the machining gap. The inner contour surfaces of the lowermost heads of the left and right cathode block units provide an electric field downward through the liquid outlet slit of the insulating jacket, concentrating the electric quantity supply. The workpiece surface directly below the liquid outlet slit of the insulating jacket is the main electrolytic action area, with a concentrated area and enhanced localization, and the current density naturally increases significantly.

[0013] The above-mentioned combined slit electrode electrolytic milling tool is characterized in that: The middle part of the above-mentioned left cathode block unit has an L-shaped structure with a right-angled bend to the right, the middle part of the right cathode block unit has an L-shaped structure with a left-angled bend to the left, the body of the insulating jacket has an L-shaped structure with a right-angled bend forward, and the body of the insulating cover plate has an L-shaped structure with a right-angled bend backward; the above-mentioned left cathode block unit, right cathode block unit, insulating jacket, and insulating cover plate are respectively fixedly connected to the electrode support plate through the horizontal end faces of their L-shaped structures, positioning them in the up-down direction with the electrode support plate. The body of the above-mentioned insulating jacket is fixed to the rear surface and the left side surface of the middle part of the left cathode block unit, and is fixed to the rear surface and the right side surface of the middle part of the right cathode block unit, positioning the insulating jacket in the front-rear direction and the left-right direction with the left and right cathode block units. The body of the above-mentioned insulating cover plate is fixed to the front surfaces of the middle parts of the left and right cathode units, positioning the insulating cover plate in the front-rear direction with the left and right cathode block units respectively.

[0014] Therefore, the cathode block is positioned in the front-back direction and left-right direction by means of the inner walls of the rectangular holes in two perpendicular directions, and then positioned in the up-down direction between the electrode support plates. These two metal parts are positioned and fixed as a whole. Then, the insulating housing is positioned in the front-back direction and left-right direction with the left and right cathode block units, the insulating cover plate is positioned in the front-back direction with the left and right cathode block units, and finally, the matching insulating cover plate is positioned in the left-right direction with the insulating housing, so as to realize the positioning, fitting and protection of the left and right cathode block units.

[0015] The above-mentioned combined slit electrode electrolytic milling tool is characterized in that: the electrode support plate and the cathode block are made of metal materials, and the insulating cover plate and the insulating housing are made of rigid insulating materials.

[0016] The above-mentioned combined slit electrode electrolytic milling tool is characterized in that: the rigid insulating material is polyether ether ketone (PEEK) or polyoxymethylene (POM).

[0017] Although the insulating cover plate and the insulating housing will not be subjected to external forces such as cutting forces during the use of the combined slit electrode electrolytic milling tool, in order to ensure the overall positioning accuracy, installation accuracy and sealing effect, the insulating materials of these two must have sufficient rigidity. Also, because the electrolyte may have certain corrosiveness, in order to avoid the insulating cover plate and the insulating housing being corroded and aged too quickly, polyether ether ketone (PEEK) and polyoxymethylene (POM) are selected to maintain a qualified service life.

[0018] The present invention has the following advantages: 1. The combined tool of the present invention has a simple structure and low cost. It does not require additional complex devices and control programs. It can perfectly confine the electric field only by the structural combination of the cathode block, the insulating cover plate and the insulating housing, and at the same time overcome the problem of difficult manufacturing of extremely narrow electrolyte flow channels. The present invention has no size limitation, and extremely narrow flow channels of any size can be obtained by changing the sizes of the cathode block, the insulating cover plate and the insulating housing, and the adaptability is very strong. In addition, when these three key components are worn or corroded and aged after long-term work, the combined structure can restore its performance by replacing the corresponding components, which is convenient, fast and cost-saving.

[0019] 2. The process method of the present invention is convenient and efficient. While controlling the electric field, it can also accelerate the electrolyte jet to a certain extent. On the one hand, it restricts the outward diffusion of the electric field from the end face and outer contour of the cathode block, and only supplies electricity more concentratedly by the inner contour of the cathode block, greatly improving the anode current density and reducing stray corrosion; on the other hand, it compresses the electrolyte by narrowing the flow channel between the relative inner contours of the two cathode block units, so that it accelerates and sprays out from the liquid outlet slit, quickly flushing away the heat and products generated by processing, ensuring the high conductivity of the electrolyte in the processing gap, and at the same time significantly improving the processing accuracy, processing localization, processing efficiency and processing surface quality. Description of the Drawings

[0020] Figure 1 is a three-dimensional structural schematic diagram of a combined slit electrode electrochemical milling tool; Figure 2 is an exploded view of the structure of a combined slit electrode electrochemical milling tool; Figure 3 is a structural schematic diagram of an electrode support plate; Figure 4 is a structural schematic diagram of a left cathode block unit; Figure 5 is a structural schematic diagram of an insulating cover plate; Figure 6 is a structural schematic diagram of an insulating sleeve; Figure 7 is a schematic diagram of combined slit electrode electrochemical milling; Figure 8 is a comparison diagram between combined slit electrode electrochemical milling and ordinary rectangular electrode electrochemical milling; where the reference numerals and names are: 1. Electrode support plate; 2. Cathode block; 3. Insulating cover plate; 4. Insulating sleeve; 5. Side pull screw; 6. Clamping bolt; 7. Gasket; 8. Nut; 9. Support bolt; 10. Fastening screw; 11. Positioning screw; 12. Workpiece; 13. Ordinary rectangular electrode; 14. Liquid outlet slit of cathode block; 15. Liquid outlet slit of insulating sleeve; 2-1. Left cathode block unit; 2-2. Right cathode block unit. Specific embodiments

[0021] The following further describes the present invention in detail with reference to the accompanying drawings: As Figure 1 and Figure 2 shown, a combined slit electrode electrochemical milling tool proposed by the present invention includes an electrode support plate 1, a left cathode block unit 2-1 and a right cathode block unit 2-2 of a cathode block 2, an insulating cover plate 3, an insulating sleeve 4, a side pull screw 5, a clamping bolt 6, a gasket 7, a nut 8, a support bolt 9, a fastening screw 10, and a positioning screw 11.

[0022] Figure 3 is a structural schematic diagram of the electrode support plate 1. The upper left is an axonometric view from below, the lower left is a top view, the left is a full-section front view, the right is a full-section left view, and the lower right is a regular isometric view. As shown in the figure, the electrode support plate 1 is a rectangular metal plate, and is symmetric about the center line in the length direction (the horizontal axis in the axonometric view from below) and the center line in the width direction (the vertical axis in the axonometric view from below). A rectangular hole is opened in its center. A pair of capsule-shaped grooves with two through holes at the bottom are symmetrically arranged on the electrode support plate 1 with respect to the center line in the length direction, distributed on both sides of the rectangular hole. The centers of the two semicircles at both ends of each capsule-shaped groove are the centers of the two through holes at its bottom, and these centers are all on the center line in the width direction of the electrode support plate 1, as Figure 3As shown in the bottom view. The electrode support plate 1 is symmetrically provided with four columns of countersunk holes arranged in parallel about the center line in the width direction, with five in each column, and two columns are arranged on each side of the rectangular hole. In the edge area near the wide side of the electrode support plate 1 outside these four columns of countersunk holes, the electrode support plate 1 is symmetrically provided with two groups of large-aperture through holes about the center line in the width direction, with three through holes in each group arranged in a "pin" shape for the positioning and clamping of the electrode support plate 1 and the machine tool spindle. The larger-diameter parts of the walls of these capsule-shaped grooves and countersunk holes are for hiding the heads of screws and bolts after inserting threaded fasteners to prevent them from protruding on the electrode support plate 1 and interfering with the positioning of the machine tool spindle.

[0023] Figure 4 It is a structural schematic diagram of the left cathode block unit 2-1. The upper left is the full-section front view, the upper right is the left view, the lower left is the full-section top view, and the lower right is the orthographic axonometric view. The right cathode block unit 2-2 has exactly the same structure as it, but is arranged symmetrically. The left cathode block unit 2-1 is a special-shaped straight prism metal block. Except for the upper and lower parallel and congruent bottom surfaces, the other surfaces of the prism are its side surfaces. The front and rear surfaces of the left cathode block unit 2-1 are these two congruent parallel bottom surfaces, which are composed of three parts: a triangular head, a middle part with an L-shaped structure, and a trapezoidal tail, as Figure 4 Shown in the full-section front view. The right-angled side surface of the triangular prism at the head of the left cathode block unit 2-1, the longest side surface of the L-shaped prism in the middle, and the parallel side surface with a smaller area of the quadrangular prism at the tail are coplanar to form the inner side surface of the left cathode block unit 2-1, which can also be called the right side surface, that is Figure 4 The surface represented by the rightmost line in the full-section front view. The right side surface and the inclined side surface of the quadrangular prism at the tail form the inner contour surface of the left cathode block unit 2-1. On the middle L-shaped prism, the relatively large parallel side surface facing the right side surface is the left side surface of the left cathode block unit 2-1. The interface between the middle L-shaped prism and the quadrangular prism at the tail is the horizontal end surface of the left cathode block unit 2-1. The holes of the left cathode block unit 2-1 are all opened on the middle L-shaped prism. Four through holes are evenly distributed along the right side surface direction in the edge area near the right side surface of the left cathode block unit 2-1 on the parallel bottom surface of the middle L-shaped prism. Two threaded blind holes are opened on the left side surface of the left cathode block unit 2-1, and two threaded holes are opened on the horizontal end surface of the left cathode block unit 2-1. The outer one is a threaded through hole, and the inner one is a threaded blind hole. The thickness of the left cathode block unit 2-1 is the same as the length of the rectangular hole on the electrode support plate 1 along the length direction of the electrode support plate 1 ( Figure 3The lengths in the horizontal direction of the bottom view are equal; the length of the parallel side with a larger area on the quadrangular prism at the tail of the left cathode block unit 2-1 is equal to the thickness of the electrode support plate 1. In this way, when the left cathode block unit 2-1 inserts the quadrangular prism at the tail into the central rectangular hole of the electrode support plate 1, the parallel side with a larger area on the quadrangular prism at the tail will contact and coincide with the hole wall of the rectangular hole on the electrode support plate 1 along the length direction of the electrode support plate 1, and the two parallel bottom surfaces of the quadrangular prism at the tail will respectively contact the two hole walls of the rectangular hole on the electrode support plate 1 along the width direction of the electrode support plate 1 ( Figure 3 in the vertical direction of the bottom view), so as to meet the positioning conditions. The positions of the two threaded holes on the horizontal end face of the left cathode block unit 2-1 correspond to the positions of the two through holes at the bottom of the capsule-shaped groove of the electrode support plate 1. After positioning, these holes will be aligned one by one, and inserting and tightening the screws can fix them. During actual use, the triangular prism at the head of the left cathode block unit 2-1 is at the bottom, and the quadrangular prism at the tail is at the top. In this way, when the left cathode block unit 2-1 and the right cathode block unit 2-2 are arranged symmetrically relative to each other, the distance between their two quadrangular prisms at the tail (i.e., the distance between the inclined side faces of the two quadrangular prisms at the tail) gradually narrows from top to bottom, which is a section of the electrolyte flow channel transition. The distance between the middle parts and the distance between the heads of the left and right cathode block units are both the same as the narrowest gap at the bottom between the two tails. This section is the extremely narrow section of the electrolyte flow channel, that is, the extremely narrow flow channel restricted by the relative inner side faces of the left and right cathode block units. The cross-section of the triangular prisms at the heads of the left and right cathode block units gradually decreases from top to bottom until it forms a ridge line. The cathode block liquid outlet slit 14 is between the two ridge lines, and the cathode block liquid outlet slit 14 is the lowest end of the extremely narrow flow channel.

[0024] Figure 5 It is a schematic structural diagram of the insulating cover plate 3. The upper left is the bottom view, the lower left is the top view, the left is the main view with a partial section, the right is the left view with a partial section, and the lower right is the orthographic axonometric drawing. As Figure 5 shown in the orthographic axonometric drawing, the overall structure of the insulating cover plate 3 is an L-shaped prism at the body part plus a quadrangular frustum at the head. The smaller side face adjacent to the side face with the largest area on the L-shaped prism at the body part and the parallel bottom surface with a larger area of the quadrangular frustum at the head share a surface. The side face with the largest area of the vertical L-shaped prism at the body part and the only vertical side face of the quadrangular frustum at the head together form the inner side face of the insulating cover plate 3, which is Figure 5 the surface represented by the rightmost line in the left view with a partial section. The larger parallel side face facing the inner side face of the insulating cover plate 3 is the outer side face of the insulating cover plate 3. The larger side face adjacent to the side face with the largest area on the L-shaped prism at the body part of the insulating cover plate 3 is the horizontal end face of the insulating cover plate 3, which is Figure 5The surface represented by the bottommost line of the partially-sectioned left view is such that the entire insulating cover plate 3 is symmetric about the center line of its inner side. Four pairs of symmetric horizontal through-holes are vertically and evenly distributed on the outer side of the insulating cover plate 3. Along the right-angle side direction, a row of five threaded blind holes is provided on the inner side of the horizontal end face of the insulating cover plate 3, and a row of five through-holes with the same arrangement is also provided on the outer side of its horizontal end face. The positions of the five threaded blind holes on the horizontal end face of the insulating cover plate 3 correspond to the positions of the counterbore holes in the inner row of the two rows on one side of the electrode support plate 1, and the positions of the five through-holes on the horizontal end face of the insulating cover plate 3 correspond to the positions of the counterbore holes in the outer row of the two rows on one side of the electrode support plate 1. During installation, through these ten pairs of aligned holes, not only can the fixing of the insulating cover plate 3 and the electrode support plate 1 be completed, but also a certain degree of sealing between the two can be achieved, preventing the electrolyte from leaking outwards from the horizontal end face of the insulating cover plate 3 when the combined tool is working. The positions of four through-holes on one side of the four pairs of through-holes on the outer side of the insulating cover plate 3 correspond to the positions of four through-holes in the middle of the left cathode block unit 2-1, and the positions of the four through-holes on the other side correspond to the positions of four through-holes in the middle of the right cathode block unit 2-2. These four pairs of holes are for fixing the insulating cover plate 3 to the left and right cathode block units, and a certain degree of sealing between the two is achieved, preventing the electrolyte from leaking outwards from the overlapping part between the inner side of the insulating cover plate 3 and the parallel bottom surfaces of the left and right cathode block units when the combined tool is working. The distance from the horizontal end face of the insulating cover plate 3 to the smaller bottom surface of its quadrangular frustum is equal to the length of the remaining surface after removing the smaller-area parallel side of the tail quadrangular prism from the right side of the left cathode block unit 2-1. This means that the maximum height of the insulating cover plate 3 and the left and right cathode block units protruding from the surface of the electrode support plate 1 is the same. After combined installation, the insulating cover plate 3 can perfectly contact and wrap the cathode block 2.

[0025] Figure 6 It is a structural schematic diagram of the insulating sleeve 4. The upper left is the bottom view, the lower left is the top view, the left is the partially-sectioned front view, the right is the partially-sectioned left view, and the lower right is the orthographic axonometric view. Comparing Figure 5 and 6 , the insulating sleeve 4 is obtained by adding a pair of approximately V-shaped prism convex platforms that are symmetric about the center line of the inner side on the basis of the insulating cover plate 3, that is, a body L-shaped prism plus a head quadrangular frustum plus a pair of convex platforms. The minimum gap at the ends of the two convex platforms is the liquid outlet slit 15 of the insulating sleeve, as shown in Figure 6 the partially-sectioned front view. As can be seen from Figure 6 the top view, the liquid outlet slit 15 of the insulating sleeve is rectangular. One parallel bottom surface of the convex platform of the insulating sleeve 4 is coplanar with the inner side of the insulating sleeve 4. The outer contour surface of this convex platform is formed by the extension and connection of the smaller bottom surface of the adjacent quadrangular frustum, the vertical side of the only vertical surface of the quadrangular frustum, and the parallel bottom surface of the L-shaped prism, as shown in Figure 6As shown in the partially-sectioned left view. The edge length of the outer contour surface of the boss of the insulating jacket 4 that coincides with the smaller bottom surface of the quadrangular frustum is less than half of the edge length where the smaller bottom surface of the quadrangular frustum intersects with the only vertical surface of the quadrangular frustum. Twice the difference between them is the slit width of the liquid outlet slit 15 of the insulating jacket. The edge length of the outer contour surface of the boss of the insulating jacket 4 that coincides with the parallel bottom surface of the L-shaped prism is less than the edge length where the inner side surface of the insulating jacket 4 intersects with the parallel bottom surface of the L-shaped prism. The thickness of the boss extended from the insulating jacket 4 is equal to the thickness of the left and right cathode block units. So from Figure 6 As can be seen from the partially-sectioned left view, there is a little space under the boss of the insulating jacket 4, which is reserved for installing the left and right cathode block units. Two vertically arranged through holes are opened in the part of the outer contour surface of the boss of the insulating jacket 4 extended from the parallel bottom surface of the L-shaped prism, as Figure 6 shown in the partially-sectioned left view. The positions of these two through holes correspond to the positions of the two threaded blind holes on the left side surface of the left cathode block unit 2-1. Two vertically arranged through holes are also opened at the corresponding positions on the symmetrically opposite boss, corresponding to the positions of the two threaded blind holes on the right side surface of the right cathode block unit 2-2. The inner contour surface of the boss of the insulating jacket 4 has the same shape and size as the remaining outer contour surfaces of the left and right cathode block units except for the inner contour surface, the horizontal end surface, all the side surfaces of the tail quadrangular prism, and the smaller area side surface facing the longest side surface of the middle L-shaped prism. In this way, after the insulating jacket 4 and the left cathode block unit 2-1 are installed and fixed together, side pull screws 5 can be inserted through the two through holes on the outer contour surface of the boss of the insulating jacket 4 and the two threaded blind holes on the left side surface of the left cathode block unit 2-1, pulling the left cathode block unit 2-1 to make the remaining outer contour surfaces except for the inner contour surface, the horizontal end surface, all the side surfaces of the tail quadrangular prism, and the smaller area side surface facing the longest side surface of the middle L-shaped prism closely fit with the inner contour surface of the boss of the insulating jacket 4 for further precise positioning. The same applies to the right cathode block unit 2-2.

[0026] Through Figure 2 、 Figure 7The installation process of the combined slit electrode electrochemical milling tool can be understood. The left and right cathode block units symmetrically insert the quadrangular prisms at their tails into the central rectangular hole of the electrode support plate 1, making the parallel sides with larger areas on the quadrangular prisms at their tails respectively contact and coincide with the two hole walls of the rectangular hole on the electrode support plate 1 along the length direction of the electrode support plate 1. The two parallel bottom surfaces of each quadrangular prism at the tail respectively contact the two hole walls of the rectangular hole on the electrode support plate 1 along the width direction of the electrode support plate 1. At the same time, the horizontal end faces of the left and right cathode block units contact the surface opposite to the capsule-shaped groove of the electrode support plate 1, thus realizing the positioning of the cathode block 2; at this time, the two threaded holes on the horizontal end faces of the left and right cathode block units are exactly aligned with the two through holes at the bottom of the capsule-shaped groove of the electrode support plate 1, and positioning screws 11 are inserted and tightened; then the insulating sleeve 4 is wrapped around the cathode block 2 along the vertical direction of its inner side surface, making the inner side surface of the insulating sleeve 4 contact the rear surfaces of the left and right cathode block units. The inner contour surface of the convex platform of the insulating sleeve 4 contacts and coincides with the remaining outer contour surfaces of the left and right cathode block units except for the inner contour surface, horizontal end face, all side surfaces of the quadrangular prism at the tail, and the smaller area side surface opposite to the longest side surface of the middle L-shaped prism. At this time, the five threaded blind holes on the horizontal end face of the insulating sleeve 4 are aligned with the five counterbore holes in the inner row of the two columns on one side of the electrode support plate 1, and fastening screws 10 are inserted and tightened. Moreover, the five through holes on the horizontal end face of the insulating sleeve 4 are aligned with the five counterbore holes in the outer row of the two columns on one side of the electrode support plate 1. Similarly, support bolts 9 are inserted, washers 7 and nuts 8 are put on and tightened; then the insulating cover plate 3 is aligned and joined with the insulating sleeve 4 along the vertical direction of its inner side surface, and its inner side surface contacts the front surfaces of the left and right cathode block units. Similarly, at this time, the five threaded blind holes on the horizontal end face of the insulating cover plate 3 are aligned with the five counterbore holes in the inner row of the two columns on the other side of the electrode support plate 1, and the five through holes on the horizontal end face of the insulating cover plate 3 are aligned with the five counterbore holes in the outer row of the two columns on the other side of the electrode support plate 1. Fastening screws 10 and support bolts 9 are respectively inserted and tightened; in addition, the four pairs of through holes evenly distributed vertically on the outer side surface of the insulating cover plate 3 are aligned with the four pairs of through holes on the outer side surface of the insulating sleeve 4, and the four through holes on one side of the four pairs of through holes are respectively aligned with the four through holes in the middle of the left and right cathode block units. Eight clamping bolts 6 are inserted, washers 7 and nuts 8 are put on and tightened, thus completing the wrapping of the cathode block 2; finally, the side pull screws 5 are inserted into the two threaded blind holes on the left side surface of the left cathode block unit 2-1 and the two threaded blind holes on the right side surface of the right cathode block unit 2-2 through the two through holes on each side of the outer contour surface of the convex platform of the insulating sleeve 4 and then tightened, completing all the assembly. The cross-sectional view after assembly is as shown in Figure 7 It can be seen that the sum of the spacing of the liquid outlet slits 15 of the insulating sleeve and the distance between the two parallel side surfaces of the quadrangular prisms at the tails of the left and right cathode block units respectively is equal to the distance between the two hole walls of the rectangular hole on the electrode support plate 1 along the length direction of the electrode support plate 1.

[0027] Figure 7It is a schematic diagram of combined slit - electrode electrochemical milling. The electrode support plate 1 is connected to the negative pole of the power supply and vertically clamped on the machine tool spindle, while the workpiece 12 is connected to the positive pole of the power supply. The electrolyte flows into the center rectangular hole of the electrode support plate 1 through the spindle, passes through the flow channel between the relative inner contour surfaces of the two cathode block units, and then sprays out from the liquid - outlet slit 15 of the insulating sleeve shell to the machining area of the workpiece 12. After being powered on, the machine tool spindle drives the combined tool to feed. Under the action of electrolysis, the material of the workpiece 12 directly below the liquid - outlet slit 15 of the insulating sleeve shell dissolves and generates a large number of insoluble electrolytic product particles, and pits appear on the surface of the workpiece 12.

[0028] Figure 8 It is a comparison diagram between combined slit - electrode electrochemical milling and ordinary rectangular - electrode electrochemical milling. Figure 8 (a) is a schematic diagram of the flow field of combined slit - electrode electrochemical milling; Figure 8 (b) is a schematic diagram of the electric field of combined slit - electrode electrochemical milling; Figure 8 (c) is a schematic diagram of the flow field of ordinary rectangular - electrode electrochemical milling; Figure 8 (d) is a schematic diagram of the electric field of ordinary rectangular - electrode electrochemical milling.

[0029] As Figure 8 shown in (c), during the processing of ordinary rectangular - electrode electrochemical milling, the electrolyte flows through the through - hole of the ordinary rectangular electrode 13 through the spindle to the machining area of the workpiece 12, and the ordinary rectangular electrode 13 and the workpiece 12 are powered on. The material of the workpiece 12 below the ordinary rectangular electrode 13 dissolves under the action of electrolysis and generates a large number of insoluble electrolytic products. The electrolyte vertically impacting the surface of the workpiece 12 overflows horizontally in all directions and diffuses outward through the machining gap. Due to the obstruction of the small machining gap, the electrolyte carrying a large number of electrolytic products cannot be completely discharged, and naturally, many product particles remain in the machining gap. During the combined slit - electrode electrochemical milling proposed by the present invention, as Figure 8 shown in (a), the narrow flow channel formed by the combination of the cathode block 2, the insulating cover plate 3, and the insulating sleeve shell 4 will compress the electrolyte, increasing the flow velocity of the electrolyte in the flow channel until it accelerates and sprays out from the liquid - outlet slit 15 of the insulating sleeve shell. The higher - speed electrolyte jet can more effectively wash away the heat and products generated during processing, reduce the residue of electrolytic products in the machining gap, ensure the high cleanliness and high conductivity of the electrolyte in the machining gap, promote the continuous and efficient progress of the electrolysis process, and effectively improve the surface quality and machining efficiency of electrochemical milling.

[0030] As Figure 8As shown in (d), during the electrolytic milling process with a common rectangular electrode, the electric field generated by the common rectangular electrode 13 will diffuse outward. In particular, the diffusion effect of the electric field edge at the bottom of the common rectangular electrode 13 is obvious, and low current density areas will be formed in the machined surface and the area to be machined, which not only wastes power supply, but also causes secondary electrolysis and stray corrosion on the machined surface, and at the same time destroys the machining efficiency, machining accuracy and machining surface quality. During the electrolytic milling process with the combined slit electrode proposed by the present invention, as Figure 8 shown in (b), the electric field is restricted by the insulating structure and cannot diffuse outward from the end face and the outer contour surface. The electric quantity is only supplied concentratedly by the inner contour surface of the cathode block 2. Moreover, the extremely narrow liquid outlet slit 14 of the combined cathode block can further concentrate the electric field, greatly increasing the anode current density on the surface of the workpiece 12 directly below the liquid outlet slit 14 of the cathode block, reducing stray corrosion while significantly improving the machining accuracy and machining localization. The machining depth is significantly increased, further promoting the electrolyte to carry the electrolytic products out as soon as possible.

[0031] The process method of the present invention can control the electric field and accelerate the electrolyte jet to a certain extent at the same time. On the one hand, it restricts the outward diffusion of the electric field from the end face and the outer contour surface of the cathode block 2, and the electric quantity is only supplied more concentratedly by the inner contour surface of the cathode block 2, greatly increasing the anode current density and reducing stray corrosion; on the other hand, the electrolyte is compressed by narrowing the flow channel between the relative inner contour surfaces of the two cathode block units, so that it accelerates and sprays out from the liquid outlet slit, quickly flushing away the heat and products generated during machining, ensuring the high conductivity of the electrolyte in the machining gap, and at the same time significantly improving the machining accuracy, machining localization, machining efficiency and machining surface quality. However, the above description should not be construed as a limitation of the patent of the present invention. It should be noted that several improvements can be made without departing from the concept of the present invention, and these should all fall within the protection scope of the patent of the present invention.

Claims

1. A combined seam electrode electrolytic milling tool, characterized in that: It comprises an electrode support plate (1), a cathode block (2), an insulating cover plate (3), and an insulating casing (4); The electrode support plate (1) is a metal plate with a rectangular hole in the center; The cathode block (2) is composed of a left cathode block unit (2-1) and a right cathode block unit (2-2); the left cathode block unit (2-1) and the right cathode block unit (2-2) are arranged symmetrically, and an electrolyte flow channel is formed between their relative inner contour surfaces; the left cathode block unit (2-1) and the right cathode block unit (2-2) are respectively divided into a tail, a middle part and a head part from top to bottom; the tail parts of the left and right cathode block units are inserted into the rectangular hole of the electrode support plate (1) for positioning, and the distance between the two tail parts gradually narrows from top to bottom; the distance between the middle parts of the left and right cathode block units and the distance between the heads are consistent with the narrowest distance at the bottom between the two tail parts; the heads of the left cathode block unit (2-1) and the right cathode block unit (2-2) are both triangular, that is, the cross-section of the heads gradually decreases from top to bottom, and finally forms a ridge line; the cathode block liquid outlet gap (14) is formed between the ridge lines formed by the heads of the left and right cathode block units; The insulating casing (4) and the insulating cover plate (3) are divided into a body and a head from top to bottom; the insulating casing (4) and the insulating cover plate (3) are fixed to the electrode support plate (1) through the body; the insulating casing (4) is located at the rear side of the left cathode block unit (2-1) and the right cathode block unit (2-2), and the inner contours of the body and the head of the insulating casing (4) match the outer contours of the middle part and the head of the cathode block (2), so that the rear side, left side, right side and lower side of the cathode block (2) are covered therein for close protection; the insulating cover plate (3) is located at the front side of the cathode block (2), so that the front side of the cathode block (2) is close protected by the insulating cover plate; An insulating casing liquid outlet slit (15) is provided at the position where the head of the insulating casing (4) overlaps with the cathode block liquid outlet slit (14); the outer contours of the insulating casing (4) and the insulating cover plate (3) heads are both prism structures with a cross-section that gradually decreases from top to bottom, gradually shrinking to the insulating casing liquid outlet slit (15) to avoid the influence of the end surface on processing.

2. The combined seam electrode electrolytic milling tool according to claim 1, characterized in that: The middle part of the left cathode block unit (2-1) is an L-shaped structure pointing rightward at a right angle, the middle part of the right cathode block unit (2-2) is an L-shaped structure pointing leftward at a right angle, the body of the insulating casing (4) is an L-shaped structure pointing forward at a right angle, and the body of the insulating cover plate (3) is an L-shaped structure pointing backward at a right angle; the left cathode block unit (2-1), the right cathode block unit (2-2), the insulating casing (4), and the insulating cover plate (3) are fixedly connected to the electrode support plate (1) through the horizontal end surfaces of their L-shaped structures, so that they are positioned in the upper and lower directions with respect to the electrode support plate (1); The insulating casing (4) is fixed to the rear surface and left side surface of the middle part of the left cathode block unit (2-1), and to the rear surface and right side surface of the middle part of the right cathode block unit (2-2), so that the insulating casing (4) is positioned with the left and right cathode block units in the front-to-back direction and the left-to-right direction; The body of the insulating cover plate (3) is fixed to the front surface of the middle part of the left and right cathode units, so that the insulating cover plate (3) is respectively positioned in the front-to-rear direction with respect to the left and right cathode block units.

3. The combined seam electrode electrolytic milling tool according to claim 1, characterized in that: The electrode support plate (1) and the cathode block (2) are made of metal materials, and the insulating cover plate (3) and the insulating casing (4) are made of rigid insulating materials.

4. The combined seam electrode electrolytic milling tool according to claim 3, characterized in that: The rigid insulating material is polyetheretherketone (PEEK) or polyoxymethylene (POM).

5. An electrolytic milling method using the combined slot electrode electrolytic milling tool according to claim 1, characterized in that The process includes: The electrode support plate (1) is connected to the negative pole of the power supply and is clamped on the main shaft of the machine tool, and the workpiece (12) is connected to the positive pole of the power supply; The electrolyte flows into the rectangular hole in the center of the electrode support plate (1) through the main shaft, passes through the flow channel between the relative inner contour surfaces of the two cathode block units, and then sprays out from the liquid outlet slit (15) of the insulating shell to the processing area of ​​the workpiece (12); During processing, the electrode support plate (1), the cathode block (2) and the workpiece (12) are energized, and the material of the workpiece (12) directly below the liquid outlet slit (15) of the insulating casing is dissolved under the action of electrolysis to produce a large amount of insoluble electrolysis product particles; The electrolyte is compressed by the narrowed flow channel when entering the gap between the relative inner contour surfaces of the two cathode block units from the rectangular hole in the center of the electrode support plate (1), and is accelerated to be ejected from the liquid outlet slit (15) of the insulating casing, so as to quickly flush away the heat and products generated by the processing, thereby ensuring the high cleanliness and high conductivity of the electrolyte in the processing gap, promoting the continuous and efficient electrolysis, and effectively improving the surface quality and processing efficiency of the electrolytic milling process; In addition, the two cathode block units are wrapped by the insulating cover plate (3) and the insulating casing (4), and the electric field cannot be diffused outward from the end face and the outer contour surface. Electricity is only concentratedly supplied through the inner contour surface, which greatly increases the anode current density, reduces stray corrosion, and significantly improves the processing accuracy and processing localization.

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