Tool cathode for electrolytic machining of a variable-pitch internal helix

Abstract

The application discloses a tool cathode for electrolytic machining of variable-pitch internal helical wire and belongs to the technical field of electrolytic machining. The tool cathode comprises a cathode body, a working tooth, a rear guide, an insulating strip and an extension sleeve. The working tooth is arranged on the peripheral surface of the cathode body, and the rear guide sleeve is arranged on the cathode body and close to the forming end of the working tooth. The insulating strip is embedded in the helical groove of the working tooth, the axial length of the insulating strip is greater than the axial length of the working tooth, and one end of the insulating strip located at the forming end protrudes from the end face of the forming end of the working tooth. The extension sleeve is sleeved on the cathode body and located between the working tooth and the rear guide, the extension sleeve is provided with an insulating tooth matched with the shape of the protruding part of the insulating strip, and the insulating tooth is embedded in cooperation with the protruding part. The peripheral surface of the rear guide is provided with an annular rectification groove. The tool cathode solves the problems of short service life of the existing cathode caused by gap discharge and poor surface quality of the machined helical wire.

Description

Technical Field

[0001] This application relates to the field of electrochemical machining technology, and in particular to a tool cathode for electrochemical machining of variable conductance inner spirals. Background Technology

[0002] Electrolytic machining is a highly efficient method for machining internal spirals. It utilizes the principle of electrochemical anodic dissolution, in which a high-speed flowing electrolyte is passed between the tool cathode and the workpiece. Under the action of a large current, the cathode rotates and feeds along the axial direction of the deep hole, ultimately electrochemically dissolving the desired spiral on the inner wall of the workpiece.

[0003] In this application, the end of the tool cathode that penetrates the workpiece is defined as the starting end, and the end that exits the workpiece is defined as the forming end, which is the end where the spiral is finally formed.

[0004] The lead of the spiral within the constant lead is constant along the axial direction. During machining, the machining gap between the working teeth of the tool cathode and the inner wall of the workpiece is basically consistent across all cross sections along the axial direction. The flow rate and pressure of the electrolyte within the gap are uniformly distributed, and the electric field lines are concentrated in the machining area directly opposite the working teeth. No stray corrosion occurs in the non-machining area.

[0005] An existing electrolytic machining tool cathode for machining helical lines with equal lead includes a cathode body, helical working teeth disposed on the outer circumference of the cathode body, and a rear guide disposed at the rear end of the working teeth. The cathode body is made of conductive material, and insulating strips are embedded in the helical grooves of the working teeth. The outer circumference of the rear guide has helical guide grooves for guiding the flow of electrolyte. The cathode body has an inlet channel and an outlet hole. The electrolyte is introduced through the inlet channel and sprayed out through the outlet hole into the machining gap. During operation, the insulating strips provide insulation and protection for non-machining areas, and the rear guide supports, positions, and maintains back pressure on the tool cathode.

[0006] However, when the aforementioned cathodes are used to process variable conductance inner spirals, quality defects such as missing corners and roughness appear at the junction of the cathode and anode of the spiral. The cathode insulation material is rapidly eroded, and usually only 1 to 3 deep tubes are processed before they are scrapped. Summary of the Invention

[0007] The purpose of this application is to provide a tool cathode for electrolytic machining of spirals with variable conductance, aiming to solve the technical problems of missing corners and roughness at the junction of the cathode and anode of the spiral when machining spirals with variable conductance, as well as the rapid ablation and short life of the cathode insulation material.

[0008] The inventors discovered that in variable-lead spirals, the lead changes continuously along the axial direction. During the tool cathode's movement, the relative motion between the working teeth and the workpiece's inner wall constantly changes, forcing the electrolyte to continuously adjust its flow direction within the spiral groove. Near the forming end, the lead change accumulates to its maximum value, resulting in the most severe flow field disturbance. This causes electrolyte flow deflection and velocity fluctuations, scouring into non-processed areas and triggering stray corrosion, leading to chipped corners and roughness at the junction of the cathode and anode of the spiral. Simultaneously, the minute gap between the end face of the insulating strip and the rear guide end face is more prone to discharge under the combined effect of the unstable flow field and electric field in variable-lead machining, exacerbating the ablation of the insulating material. These problems severely restrict the machining efficiency and product quality of variable-lead spirals.

[0009] To solve the above-mentioned technical problems, this application provides the following technical solution:

[0010] A tool cathode for electrolytic machining of a variable-lead internal helix includes: a cathode body, which is cylindrical, with working teeth distributed along the helical direction on its outer circumference, the working teeth being used for electrolytic machining of the variable-lead internal helix; the tool cathode having a starting end and a forming end, the starting end being the end where the tool cathode enters the workpiece, the forming end being the end where the tool cathode exits the workpiece, and the forming end being the end where the helix is ​​finally formed during electrolytic machining; a rear guide, sleeved on the cathode body and close to the forming end of the working teeth; and an insulating strip, embedded in the helical groove of the working teeth, the axial length of the insulating strip being greater than the helical groove of the working teeth. The axial length of the working tooth is such that one end of the insulating strip at the forming end protrudes from the forming end face of the working tooth; an extension sleeve is fitted onto the cathode body and located between the working tooth and the rear guide, the extension sleeve having insulating teeth that match the shape of the protruding part of the insulating strip, the insulating teeth being fitted into the protruding part; an annular rectifier groove is provided on the outer circumferential surface of the rear guide; the cathode body has an inlet channel and an outlet hole, the inlet channel being a blind hole opened along the axial direction of the cathode body, one end of the outlet hole being connected to the inlet channel, and the other end extending into the spiral groove of the working tooth.

[0011] Optionally, the thickness of the insulating strip is greater than the depth of the spiral groove of the working tooth, so that the outer surface of the insulating strip protrudes from the outer circumferential surface of the working tooth; the outer surface of the insulating strip is an arc surface, the axis of which coincides with the axis of the inner wall of the workpiece, and the outer surfaces of all the insulating strips are located on the same cylindrical surface at equal intervals from the inner wall of the workpiece.

[0012] Optionally, the insulating strip is fitted into the spiral groove of the working tooth with a clearance fit, and the end face of the insulating strip at one end of the starting end is flush with the end face of the starting end of the working tooth.

[0013] Optionally, after the insulating teeth of the extension sleeve are fitted into the protruding part of the insulating strip, the outer surface of the protruding part of the insulating strip is located on the first cylindrical surface, and the outer surface of the insulating teeth of the extension sleeve is located on the second cylindrical surface, wherein the diameter of the first cylindrical surface is larger than the diameter of the second cylindrical surface.

[0014] Optionally, the rear guide sleeve is disposed on the side of the extension sleeve opposite to the working tooth and is threadedly connected to the cathode body.

[0015] Optionally, the radial height of the working tooth gradually increases from the starting end to the forming end.

[0016] Optionally, a spiral guide groove is also provided on the outer peripheral surface of the rear guide, and the lead of the spiral guide groove is the same as the lead of the working tooth.

[0017] Optionally, it also includes a front guide, which is disposed at the starting end of the tool cathode. The outer surface of the front guide is provided with a liquid passage groove along the extension direction of the working tooth, and the bottom of the liquid passage groove is smoothly connected to the top surface of the working tooth.

[0018] Optionally, the front guide is provided with a sealing ring mounting groove and a sealing ring disposed in the sealing ring mounting groove.

[0019] Optionally, the liquid outlet is an oblique hole, and there are multiple liquid outlet holes, which are arranged alternately along the extension direction of the working tooth; one end of the oblique hole is connected to the liquid inlet channel, and the other end extends to the liquid passage groove, and the oblique hole is inclined from the starting end to the forming end along the axial direction of the cathode body.

[0020] The technical solution provided in this application has the following beneficial effects:

[0021] One end of the insulating strip protrudes from the end face of the working tooth forming end, preventing the end face of the insulating strip from contacting the end face of the rear guide, thus eliminating the physical conditions for gap discharge between them. The extension sleeve is located between the working tooth and the rear guide, with its insulating teeth interlocking with the protruding part of the insulating strip, completely filling the space between the insulating strip and the rear guide, sealing the original gap. The combination of these two structures cuts off the gap discharge channel caused by flow field disturbances during variable lead machining, suppresses electrolytic erosion of the cathode insulating material, and extends the cathode's service life.

[0022] Simultaneously, the interlocking fit between the insulating strip and the extension sleeve creates a height difference between the outer surface of the insulating strip and the outer surface of the insulating teeth of the extension sleeve. Specifically, the diameter of the cylindrical surface containing the outer surface of the insulating strip is larger than the diameter of the cylindrical surface containing the outer surface of the insulating teeth of the extension sleeve. The extension sleeve area, relative to the insulating strip area, forms an expanded electrolyte flow space. During variable lead machining, the electrolyte, whose flow direction is deflected due to continuous lead changes, experiences a decrease in velocity and an increase in pressure as it flows through this expanded space. The flow direction is then readjusted, preventing it from flowing into the non-machined area in a deflected direction. The annular rectifier groove on the outer circumference of the guide tube further integrates the electrolyte flowing out of the forming end, making the velocity and pressure distribution more uniform and stabilizing the flow field within the machining gap at the forming end.

[0023] The three structural features mentioned above work together to address the flow field disturbance caused by the continuous change of lead in the machining of spirals with variable lead, thereby suppressing stray corrosion in the forming end area. The line corners at the junction of the male and female leads of the spiral are complete and clear, and there are no more missing corners or roughness, thus realizing stable electrolytic machining of spirals with variable lead.

[0024] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 It is a three-dimensional schematic diagram of a workpiece with a variable lead internal helix;

[0027] Figure 2 It is a three-dimensional sectional view of a workpiece with a variable lead internal helix;

[0028] Figure 3 This is a front view of the tool cathode for electrolytic machining of variable conductance inner spirals provided in an embodiment of this application;

[0029] Figure 4 yes Figure 3 Cross-sectional view at point AA;

[0030] Figure 5 yes Figure 3 A schematic diagram of the decomposition process;

[0031] Figure 6 This is a perspective view of the cathode body in the tool cathode for electrolytic machining of variable conductance inner spirals provided in the embodiments of this application;

[0032] Figure 7 This is a perspective view of the front guide in the tool cathode for electrolytic machining of variable lead internal spirals provided in the embodiments of this application;

[0033] Figure 8 This is a cross-sectional view of the extension sleeve in the tool cathode for electrolytic machining of variable lead internal spirals provided in an embodiment of this application;

[0034] Figure 9 This is a perspective view of the tool cathode for electrolytic machining of variable-lead inner spirals provided in the embodiments of this application.

[0035] Explanation of reference numerals in the attached figures

[0036] 1-Cathode body; 101-Outlet hole; 102-Working tooth; 103-Inlet channel; 2-Sealing rubber ring; 3-Pressure nut; 4-Front guide; 401-Passing groove; 402-Sealing ring mounting groove; 5-Sealing ring; 6-Insulating strip; 7-Extension sleeve; 701-Insulating tooth; 8-Rear guide; 801-Annular rectifier groove; 802-Spiral guide groove; 9-Screw cap; 10-Workpiece; 1001-Variable lead inner spiral. Detailed Implementation

[0037] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0038] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the relative positions of the corresponding components in the direction of gravity when they are in use, while "inner" and "outer" refer to their relative positions to the contours of the corresponding components themselves. Furthermore, the terms "first," "second," etc., used in this application are for distinguishing one element from another and do not imply sequentiality or importance. In the following description, when referring to the accompanying drawings, unless otherwise explained, the same reference numerals in different drawings denote the same or similar elements.

[0039] The present application will now be described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the application.

[0040] refer to Figure 1 and Figure 2 The workpiece 10 is tubular, and its inner wall has a variable-lead internal helical groove 1001. This invention provides a tool cathode for electrolytic machining of tubes with variable-lead internal helical grooves on their inner walls.

[0041] According to the embodiments of this application, refer to Figures 3 to 9The tool cathode includes a cathode body 1, a rear guide 8, an insulating strip 6, and an extension sleeve 7. The tool cathode uses the cathode body 1 as its mounting base. The cathode body 1 is a cylindrical structure, which can be made of brass and serves to conduct electricity and provide support.

[0042] refer to Figure 5 and Figure 6 The outer peripheral surface of the cathode body 1 is machined with working teeth 102 extending in a spiral direction. The tooth shape of the working teeth 102 is a single-sided cutting wedge structure, with the right end being the starting end and the left end being the forming end.

[0043] The starting end of the tool cathode is defined as the end that enters the workpiece 10, and the forming end is defined as the end that exits the workpiece 10. The forming end is also the end where the spiral is finally formed. A rear guide 8 is sleeved on one side of the forming end of the cathode body 1. The rear guide 8 is made of insulating material and has a spiral groove with the same lead as the working tooth 102 milled on its outer circle to guide the flow of electrolyte.

[0044] refer to Figure 3 and Figure 4 An insulating strip 6 is embedded in the spiral groove of the working tooth 102. The axial length of the insulating strip 6 is designed to be greater than the axial length of the working tooth 102. After assembly, one end of the insulating strip 6 located at the forming end extends outward from the forming end face of the working tooth 102. This protruding structure prevents the insulating strip 6 from directly contacting the end face of the rear guide 8, eliminating the tiny gap caused by contact in traditional structures and thus eliminating the physical conditions for gap discharge under the action of a high-voltage electric field.

[0045] refer to Figure 3 , Figure 4 and Figure 5 An extension sleeve 7 is fitted onto one side of the formed end of the cathode body 1, between the working tooth 102 and the rear guide 8. The extension sleeve 7 is made of insulating material and has insulating teeth 701 machined to match the shape of the protruding portion of the insulating strip 6. During assembly, the protruding portion of the insulating strip 6 is inserted into the insulating teeth 701 of the extension sleeve 7, forming an interlocking fit. Optionally, the extension sleeve 7 is fitted into the cathode body 1 with a clearance fit and coaxially, and is glued in place, with each insulating tooth 701 interlocking with the protrusion of the insulating strip 6. This interlocking fit fills the space between the insulating strip 6 and the rear guide 8, preventing gap discharge.

[0046] refer to Figure 3 and Figure 8 An annular rectifier groove 801 is machined on the outer peripheral surface of the guide 8. The annular rectifier groove 801 is closed circumferentially. After the electrolyte flows through the forming end of the working tooth 102, the annular rectifier groove 801 reorganizes the electrolyte, making the flow rate and pressure distribution more uniform, providing appropriate back pressure for the forming end, and preventing flow field turbulence.

[0047] refer to Figure 6 The cathode body 1 has an axially oriented liquid inlet channel 103, which is a blind hole. The cathode body 1 also has a liquid outlet hole 101, one end of which communicates with the liquid inlet channel 103, and the other end extends into the spiral groove of the working tooth 102. After entering through the liquid inlet channel 103, the electrolyte is sprayed out through the liquid outlet hole 101 into the spiral groove of the working tooth 102, forming a uniform electrolyte flow field in the gap between the tool cathode and the inner wall of the workpiece 10.

[0048] With the combination of the above structures, the tool cathode can maintain a stable flow field distribution during electrolytic machining, eliminating discharge gaps and flow channel steps, thereby extending the service life of the cathode and improving the surface quality of the spiral.

[0049] According to the embodiments of this application, refer to Figure 3 and Figure 5 The thickness of the insulating strip 6 is designed to be greater than the depth of the spiral groove of the working tooth 102. After assembly, the outer surface of the insulating strip 6 protrudes from the outer peripheral surface of the working tooth 102. This protruding structure allows the outer surface of the insulating strip 6 to form an electrolyte flow gap with the inner wall of the workpiece 10, while isolating the non-machined area from the electric field.

[0050] The outer surface of the insulating strip 6 is an arc surface, and the axis of this arc surface coincides with the axis of the inner wall of the workpiece 10. The outer surfaces of all the insulating strips 6 are located on the same cylindrical surface that is equidistant from the inner wall of the workpiece 10. The equidistant gap between this cylindrical surface and the inner wall of the workpiece 10 ensures that the electrolyte is evenly distributed circumferentially in the processing area, so that the processing area corresponding to the working tooth 102 receives a stable supply of electrolyte.

[0051] The insulating strip 6 is made of insulating material, and its outer surface is higher than the outer circumferential surface of the working tooth 102, forming a non-conductive isolation layer between the tool cathode and the inner wall of the workpiece 10. During machining, a certain gap exists between the outer circumferential surface of the working tooth 102 and the inner wall of the workpiece 10, within which the electrolyte flows. The protruding portion of the insulating strip 6 fills the gap in the non-machined area, concentrating the electric field energy on the etching area corresponding to the working tooth 102, thus reducing stray corrosion.

[0052] This structure concentrates the electrolyte in the etching area, preventing anodic dissolution in non-processed areas. When machining spirals with varying conductance, the angles at the junction of the cathode and anode lines are clear, without missing corners or roughness. Simultaneously, the equidistant gap between the arc surface of the insulating strip 6 and the inner wall of the workpiece 10 ensures a consistent machining gap along the circumference and a uniform current density distribution.

[0053] According to an embodiment of this application, the insulating strip 6 is fitted into the spiral groove of the working tooth 102 with a clearance fit. The clearance fit provides sufficient installation allowance for the assembly of the insulating strip 6, ensuring that the insulating strip 6 will not be damaged due to interference when embedded in the spiral groove, and at the same time, it facilitates fixing the insulating strip 6 in the spiral groove by adhesive.

[0054] The end face of the insulating strip 6 at one end of the starting end is aligned with the end face of the starting end of the working tooth 102, and the two remain flush. This flush structure ensures that when the electrolyte flows from the inlet channel 103 through the outlet hole 101 into the spiral groove of the working tooth 102, it will not encounter any steps or obstructions at the starting end, and can flow smoothly forward along the spiral groove.

[0055] During electrolytic machining, the electrolyte flows into the spiral groove of the working tooth 102 from one side of the starting end. The flush end face of the starting end ensures that the initial conditions for electrolyte flow are consistent, preventing local separation or eddies caused by uneven end faces. The clearance fit between the insulating strip 6 and the spiral groove also allows for fine-tuning of the position during assembly to ensure that the protruding length of the formed end of the insulating strip 6 is consistent.

[0056] According to the embodiments of this application, refer to Figure 3 and Figure 4 After the insulating teeth 701 of the extension sleeve 7 are fitted into the protruding part of the insulating strip 6, the outer surface of the protruding part of the insulating strip 6 is located on the first cylindrical surface, and the outer surface of the insulating teeth 701 of the extension sleeve 7 is located on the second cylindrical surface. The diameter of the first cylindrical surface is larger than the diameter of the second cylindrical surface.

[0057] After assembly, the outer peripheral surface of the protruding portion of the insulating strip 6 is higher than the outer surface of the insulating teeth 701 of the extension sleeve 7, creating a height difference between them. The outer surface of the insulating teeth 701 of the extension sleeve 7 is recessed relative to the outer surface of the protruding portion of the insulating strip 6, providing a flow space for the electrolyte. When the electrolyte flows from the spiral groove of the working tooth 102 through the forming end, the gap between the outer surface of the insulating strip 6 and the inner wall of the workpiece 10 constitutes the main flow channel of the electrolyte. However, the outer surface of the insulating teeth 701 of the extension sleeve 7 is lower than the recessed area formed by the outer surface of the insulating strip 6, causing the cross-sectional area of ​​the flow channel to suddenly expand, the flow velocity to decrease, and the pressure to rise when the electrolyte enters the area of ​​the extension sleeve 7, thus playing a role in buffering and stabilizing the flow.

[0058] This height difference structure allows the electrolyte to smoothly enter the area between the extension sleeve 7 and the inner wall of the workpiece 10 after flowing through the forming end of the working tooth 102, avoiding flow obstruction and pressure increase caused by the sudden contraction of the flow channel cross-sectional area.

[0059] According to the embodiments of this application, refer to Figures 3 to 5The rear guide 8 is sleeved on the side of the extension sleeve 7 away from the working tooth 102, that is, the extension sleeve 7 is located in the axial position between the working tooth 102 and the rear guide 8. The inner hole of the rear guide 8 is connected to the cathode body 1 by threads. After tightening, the end face of the rear guide 8 abuts against the end face of the extension sleeve 7, pressing and fixing the extension sleeve 7 to one side of the forming end of the working tooth 102.

[0060] The threaded connection of the rear guide 8 enables detachable fastening, facilitating the assembly, adjustment, and replacement of various components. The rear guide 8 clamps the extension sleeve 7 axially between the working tooth 102 and the rear guide 8, preventing axial movement of the extension sleeve 7 during processing and ensuring the stability of the interlocking fit between the extension sleeve 7 and the protruding part of the insulating strip 6.

[0061] The rear guide 8 is sleeved on the outside of the extension sleeve 7. Its inner hole and the outer cylindrical surface of the extension sleeve 7 can be fitted with a clearance fit. This fit ensures the concentricity between the two and allows for thermal expansion and contraction during temperature changes. The outer circle of the rear guide 8 also serves as a guide to ensure the coaxiality between the tool cathode and the workpiece 10.

[0062] According to the embodiments of this application, refer to Figure 5 and Figure 6 The radial height of the working tooth 102 gradually increases from the starting end to the forming end. This change is achieved by machining an axial taper on the outer circumferential surface of the working tooth 102.

[0063] The gradual increase in radial height of the working teeth 102 creates a gradual change in the machining clearance from the starting end to the forming end. During electrolytic machining, the electrolyte flows from the starting end to the forming end. As electrochemical dissolution proceeds, the composition and conductivity of the electrolyte within the machining clearance change along the flow direction. The gradual increase in the height of the working teeth 102 compensates for the change in the machining clearance, ensuring sufficient machining allowance at the forming end and guaranteeing that the helix has a complete tooth profile in the final forming process.

[0064] This structural design ensures that the machining quality of the spiral within the variable lead remains consistent along the axial direction, and that the line angle at the forming end is full, without any missing corners due to changes in the flow field.

[0065] According to the embodiments of this application, refer to Figure 5 and Figure 9 A spiral guide groove 802 is also machined on the outer peripheral surface of the rear guide 8. The lead of the spiral guide groove 802 is the same as the lead of the working tooth 102. The spiral guide groove 802 is located on one side of the starting end of the annular rectifier groove 801 in the axial direction, and is used to guide the electrolyte from the spiral groove of the working tooth 102 to the outer surface of the rear guide 8.

[0066] The spiral guide groove 802 and the spiral groove of the working tooth 102 have the same lead, ensuring that the electrolyte flows in the same direction as it flows from the working tooth 102 region into the guide region 8. If the leads were different, the electrolyte would be subjected to inertial forces caused by the change in direction in the transition region, inducing turbulence. The same lead ensures the continuity of the electrolyte flow direction and reduces flow resistance.

[0067] The spiral guide channel 802 is responsible for guiding the flow direction of the electrolyte, while the annular rectifier channel 801 is responsible for regulating the flow velocity distribution of the electrolyte. The two work together to keep the electrolyte stable after it exits the forming end.

[0068] According to the embodiments of this application, refer to Figure 5 and Figure 7 The tool cathode is also provided with a front guide 4. The front guide 4 is located at the starting end of the tool cathode, that is, in front of the starting end of the working tooth 102. The front guide 4 is assembled with the cathode body 1 by means of a threaded connection.

[0069] The outer surface of the front guide 4 is machined with a liquid-passing groove 401 along the extension direction of the working tooth 102. The bottom of the liquid-passing groove 401 is smoothly connected to the top surface of the working tooth 102. The liquid-passing groove 401 guides the electrolyte from the outlet hole 101 into the spiral groove formed by the working tooth 102 and the insulating strip 6. The outlet hole 101 penetrates the wall of the front guide 4 and communicates with the liquid-passing groove 401. After the electrolyte is sprayed out from the outlet hole 101, it directly enters the liquid-passing groove 401 and flows along the liquid-passing groove 401 to the spiral groove formed by the working tooth 102 and the insulating strip 6.

[0070] The front guide 4 plays a positioning and guiding role in the electrolytic machining process, ensuring the coaxiality between the tool cathode and the workpiece 10. At the same time, the liquid passage groove 401 on the outer surface of the front guide 4 smoothly connects with the spiral groove of the working tooth 102, so that the flow path of the electrolyte before entering the working area is unobstructed, without generating additional pressure loss or sudden changes in flow direction.

[0071] According to the embodiments of this application, refer to Figure 3 , Figure 5 and Figure 7 The front guide 4 has a sealing ring mounting groove 402, and a sealing ring 5 is placed in the sealing ring mounting groove 402. The sealing ring 5 is made of rubber material and has an O-ring structure, which is assembled into the annular groove on the outer circumference of the front guide 4.

[0072] The sealing ring 5 forms an elastic contact seal between the front guide 4 and the inner wall of the workpiece 10, preventing electrolyte from leaking forward along the gap between the front guide 4 and the workpiece 10. Under high-pressure electrolyte conditions, the sealing ring 5 is pressed between the sealing ring mounting groove 402 of the front guide 4 and the inner wall of the workpiece 10, preventing electrolyte from bypassing the front guide 4 and flowing to the non-working area of ​​the tool cathode.

[0073] The number of sealing ring mounting grooves 402 is two rows, each row is closed circumferentially along the front guide 4, and the two rows of sealing rings 5 ​​are arranged axially at intervals. The double-row sealing ring 5 structure provides a redundant sealing effect. Even if one sealing ring 5 wears, the other sealing ring 5 can still maintain the sealing performance, ensuring the stability of electrolyte pressure and flow.

[0074] According to the embodiments of this application, refer to Figure 5 The liquid outlet 101 has an oblique hole structure. The liquid outlet 101 extends outward from the inside of the cathode body 1, with one end inside the cathode body 1 communicating with the liquid inlet channel 103, and the other end outside the cathode body 1 extending to the liquid passage 401. The liquid outlet 101 is inclined along the axial direction of the cathode body 1 from the starting end to the forming end.

[0075] There are multiple outlet holes 101, which are staggered along the extension direction of the working teeth 102. Based on the helical direction of the working teeth 102, the projected positions of each outlet hole 101 on the helical path are staggered and not on the same circumference. This staggered arrangement makes the distribution density of the outlet holes 101 uniform in the circumferential direction of the cathode body 1, avoiding uneven electrolyte supply caused by the outlet holes 101 being concentrated in a certain circumferential area.

[0076] After the electrolyte flows into each inclined hole from the inlet channel 103, it is ejected from the inside of the cathode body 1 along the inclined holes and enters the spiral groove formed by the working tooth 102 and the insulating strip 6 through the liquid passage 401 of the front guide 4. The inclination direction of the inclined holes is consistent with the flow direction of the electrolyte in the spiral groove, which reduces the flow diversion loss when the electrolyte is ejected from the outlet hole 101. The staggered arrangement makes the outlet holes 101 uniformly distributed in the circumferential direction, ensuring that the electrolyte supply in each spiral groove of the working tooth 102 is consistent, and the flow field in the machining gap is symmetrically distributed in the circumferential direction.

[0077] According to the embodiments of this application, refer to Figures 3 to 9 The working principle of the tool cathode of the present invention will be explained below with reference to specific embodiments. The tool cathode includes a cathode body 1, a rear guide 8, an insulating strip 6, an extension sleeve 7, a front guide 4, a sealing ring 5, a water-sealing rubber ring 2, a clamping nut 3, and a screw cap 9.

[0078] For example, the outer peripheral surface of the cathode body 1 is machined with sixteen working teeth 102, the helix angle of each working tooth 102 gradually changing from 15° at the starting end to 25° at the forming end. The radial height of the working teeth 102 gradually increases from 2 mm to 3.5 mm from the starting end to the forming end. A liquid inlet channel 103 is machined along the axis inside the cathode body 1, which is drilled from the end face of the starting end of the cathode body 1 and terminates on the forming end side of the working teeth 102. Sixteen liquid outlet holes 101 are machined on the cathode body 1, arranged in two staggered rows, each liquid outlet hole 101 extending obliquely from the liquid inlet channel 103 towards the outer peripheral surface of the working teeth 102, the oblique direction being consistent with the helix direction of the working teeth 102.

[0079] Before processing begins, the operator installs the cathode body 1 onto the spindle pull rod of the electrolytic machining machine. The front guide 4 is inserted into and tightened onto the external thread of the cathode body 1 from its starting end, positioning it in front of the starting end of the working tooth 102. The clamping nut 3 is inserted into and tightened onto the right side of the front guide 4 from its starting end, axially pressing and fixing the front guide 4 to prevent axial movement during processing. The sealing ring 5 is inserted into the annular groove of the front guide 4 to ensure a seal between the front guide 4 and the inner wall of the workpiece 10. The water-sealing rubber ring 2 is fitted onto the external threaded cylindrical surface of the cathode body 1, located to the right of the clamping nut 3. After the cathode body 1 is connected to the electrolyte delivery device, the water-sealing rubber ring 2 is pressed between the connecting end faces to prevent electrolyte leakage from the connection point. Insulating strip 6 is inserted into each spiral groove from the starting end of working tooth 102. The end face of insulating strip 6 at the starting end is aligned with the end face of working tooth 102 at the starting end, and the end face at the forming end extends 2 mm from the end face of forming end of working tooth 102. Extension sleeve 7 is fitted into cathode body 1 from the forming end. The insulating teeth 701 on its inner wall are aligned with the protruding part of insulating strip 6 and then fitted in. The diameter of the first cylindrical surface of the outer surface of the protruding part of insulating strip 6 is larger than the diameter of the second cylindrical surface of the outer surface of insulating teeth 701 of extension sleeve 7. Rear guide 8 is fitted into the end of extension sleeve 7 and connected to cathode body 1 by threads and tightened, pressing extension sleeve 7 between the end face of forming end of working tooth 102 and rear guide 8.

[0080] The screw cap 9 is made of insulating material and is a stepped columnar shape. The small-diameter cylindrical surface is machined with fine threads and is assembled into the threaded hole at the end of the rear guide 8. The end face of the large-diameter cylinder fits against the end face of the rear guide 8, which on the one hand prevents electrolyte from seeping into the cathode body 1, and on the other hand serves as insulation.

[0081] The assembled tool cathode is inserted into the deep-hole workpiece 10 to be machined. The workpiece 10 is fixed on the machine tool table, and the tool cathode moves along the axial direction of the workpiece 10 under the traction of the pull rod, while rotating around its own axis. Electrolyte enters the inlet channel 103 of the cathode body 1 from the machine tool's supply system, sprays out through the outlet hole 101, and flows into the spiral groove of the working tooth 102 along the liquid passage 401 of the front guide 4, filling the machining gap between the tool cathode and the inner wall of the workpiece 10. After the electrolytic machining power is turned on, the inner wall of the workpiece 10 undergoes electrochemical dissolution in the area corresponding to the working tooth 102. The equidistant gap between the outer surface of the insulating strip 6 and the inner wall of the workpiece 10 concentrates the electric field energy in the erosion area corresponding to the working tooth 102, while the non-machined area is protected by the insulating strip 6 and does not dissolve.

[0082] As the tool cathode moves axially from the starting end to the forming end, the radial height of the working tooth 102 gradually increases, and the machining clearance gradually changes axially, compensating for the conductivity changes in the electrolyte flow direction. After flowing through the forming end of the working tooth 102, the electrolyte passes through the smooth transition area of ​​the extension sleeve 7 and enters the rear guide 8. The spiral guide groove 802 on the outer periphery of the rear guide 8 guides the electrolyte to the annular rectifier groove 801, which reorganizes the electrolyte, making the flow rate and pressure distribution uniform.

[0083] After machining, the tool cathode passes through the formed end of the workpiece 10, and a variable-lead internal helix corresponding to the shape of the working tooth 102 is formed on the inner wall of the workpiece 10. The entire process realizes stable electrolytic machining of variable-lead internal helices in small-diameter deep holes.

[0084] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this application will not describe the various possible combinations separately.

[0085] Furthermore, various different implementations of this application can be combined in any way, as long as they do not violate the spirit of this application, they should also be regarded as the content disclosed in this application.

Claims

1. A tool cathode for electrolytic machining of variable conductance inner spirals, characterized in that, include: The cathode body (1) is cylindrical, and its outer circumferential surface is provided with working teeth (102) distributed along the spiral direction. The working teeth (102) are used for electrolytic machining of the variable lead internal spiral (1001) of the workpiece (10). The tool cathode has a starting end and a forming end. The starting end is the end where the tool cathode enters the workpiece (10), and the forming end is the end where the tool cathode exits the workpiece (10). The forming end is the end where the spiral is finally formed during electrolytic machining. The rear guide (8) is sleeved on the cathode body (1) and close to the forming end of the working tooth (102); An insulating strip (6) is embedded in the spiral groove of the working tooth (102). The axial length of the insulating strip (6) is greater than the axial length of the working tooth (102) so that one end of the insulating strip (6) at the forming end protrudes from the forming end face of the working tooth (102). An extension sleeve (7) is fitted onto the cathode body (1) and located between the working tooth (102) and the rear guide (8). The extension sleeve (7) is provided with insulating teeth (701) that match the shape of the protruding part of the insulating strip (6). The insulating teeth (701) are fitted into the protruding part. The rear guide (8) has an annular rectifier groove (801) on its outer peripheral surface. The cathode body (1) is provided with an inlet channel (103) and an outlet hole (101). The inlet channel (103) is a blind hole opened along the axial direction of the cathode body (1). One end of the outlet hole (101) is connected to the inlet channel (103), and the other end extends into the spiral groove of the working tooth (102).

2. The tool cathode according to claim 1, characterized in that, The thickness of the insulating strip (6) is greater than the spiral groove depth of the working tooth (102) so that the outer surface of the insulating strip (6) protrudes from the outer circumferential surface of the working tooth (102); the outer surface of the insulating strip (6) is an arc surface, the axis of which coincides with the axis of the inner wall of the workpiece (10), and the outer surfaces of all the insulating strips (6) are located on the same cylindrical surface at equal intervals with the inner wall of the workpiece (10).

3. The tool cathode according to claim 1, characterized in that, The insulating strip (6) is fitted into the spiral groove of the working tooth (102) with a clearance fit, and the end face of the insulating strip (6) at one end of the starting end is flush with the end face of the starting end of the working tooth (102).

4. The tool cathode according to claim 1, characterized in that, After the insulating teeth (701) of the extension sleeve (7) are fitted into the protruding part of the insulating strip (6), the outer surface of the protruding part of the insulating strip (6) is located on the first cylindrical surface, and the outer surface of the insulating teeth (701) of the extension sleeve (7) is located on the second cylindrical surface. The diameter of the first cylindrical surface is larger than the diameter of the second cylindrical surface.

5. The tool cathode according to claim 1, characterized in that, The rear guide (8) is sleeved on the side of the extension sleeve (7) away from the working tooth (102) and is threadedly connected to the cathode body (1).

6. The tool cathode according to claim 1, characterized in that, The radial height of the working tooth (102) gradually increases from the starting end to the forming end.

7. The tool cathode according to claim 1, characterized in that, The outer circumferential surface of the rear guide (8) is also provided with a spiral guide groove (802), the lead of the spiral guide groove (802) is the same as the lead of the working tooth (102).

8. The tool cathode according to claim 1, characterized in that, It also includes a front guide (4), which is located at the starting end of the tool cathode. The outer surface of the front guide (4) is provided with a liquid passage groove (401) along the extension direction of the working tooth (102). The bottom of the liquid passage groove (401) is smoothly connected to the top surface of the working tooth (102).

9. The tool cathode according to claim 8, characterized in that, The front guide (4) is provided with a sealing ring mounting groove (402) and a sealing ring (5) disposed in the sealing ring mounting groove (402).

10. The tool cathode according to claim 8, characterized in that, The liquid outlet hole (101) is an oblique hole, and there are multiple liquid outlet holes (101), which are staggered along the extension direction of the working tooth (102); one end of the oblique hole is connected to the liquid inlet channel (103), and the other end extends to the liquid passage (401), and the oblique hole is inclined from the starting end to the forming end along the axial direction of the cathode body (1).

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