Electrical processing method for folding groove of super-fine long stainless steel pipe

Abstract

The present application relates to a kind of super long stainless steel pipe breakage groove electroprocessing method, belong to super long pipe processing technical field, solve the problem that high-precision processing breakage groove on super long stainless steel pipe is difficult to be realized in prior art.The method includes the working state of the multiple circumferential arrangement of the tool electrode electric spark machining point on stainless steel pipe to realize the processing of breakage groove on the surface to be processed;Wherein, the same electric spark machining point includes working state and non-working state;When the distance between electric spark machining point and the surface to be processed is greater than threshold value, electric spark machining point is non-working state;When the distance between electric spark machining point and the surface to be processed is less than or equal to threshold value, electric spark machining point is working state;Threshold value is the discharge distance between electric spark machining point and the surface to be processed to meet processing requirement.High-precision processing of breakage groove on super long stainless steel pipe is realized, and it can be processed in place at one time, and processing efficiency is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of ultra-slender tube processing technology, and in particular to an electrical discharge machining method for a fracture groove in an ultra-slender stainless steel tube. Background Technology

[0002] Some ultra-slender flight products require the machining of breakaway grooves to separate the guidance system from the fairing when the product reaches a predetermined altitude and position. Due to the small diameter and thin wall thickness of these ultra-slender flight products, the breakaway grooves must be even smaller. For flight products where dimensional control is crucial, the precision requirements for machining these breakaway grooves place higher demands on the machining methods.

[0003] Traditional turning methods are insufficient to meet the machining accuracy requirements of fracture grooves. This is because the clamping of the part and the application of cutting forces during turning inevitably affect the machining accuracy of the fracture grooves.

[0004] Therefore, in order to meet the processing requirements of fracture grooves on ultra-slender aircraft products, it is necessary to explore new fracture groove processing methods. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide an electrical discharge machining method for creating a break groove in an ultra-slender stainless steel tube, thereby solving the problem that it is difficult to achieve high-precision machining of break grooves on ultra-slender stainless steel tubes.

[0006] On one hand, embodiments of the present invention provide an electrical discharge machining method for creating a break groove in an ultra-slender stainless steel tube, which includes utilizing the working state of multiple electrical discharge machining points arranged around the circumference of the stainless steel tube using a tool electrode to realize the machining of the break groove on the surface to be machined.

[0007] Specifically, by changing the distance between the EDM point and the surface to be processed, the same EDM point can be in a working state or a non-working state.

[0008] Based on a further improvement of the above method, the lower end of the tool electrode is a discharge end, and the discharge end is provided with multiple electrical discharge machining points. During machining, the multiple electrical discharge machining points arranged around the circumference of the stainless steel tube are continuously and uninterruptedly distributed around the circumference of the stainless steel tube.

[0009] Based on a further improvement of the above method, during processing, multiple EDM points arranged around the circumference of the stainless steel tube form a continuous ring shape, and the inner circle of the ring matches the shape of the break groove.

[0010] Based on a further improvement of the above method, the discharge end of the tool electrode is sleeved on a stainless steel tube, and during processing, the discharge end of the tool electrode makes an eccentric movement around the central axis of the inner cavity of the stainless steel tube.

[0011] Based on a further improvement of the above method, the inner diameter of the discharge end of the tool electrode is 5 to 10 times the outer diameter of the stainless steel tube. Before processing, the position of the stainless steel tube is adjusted so that the central axis of the inner cavity of the stainless steel tube coincides with the center line of the inner circle of the discharge end.

[0012] Based on the further improvement of the above method, before processing, two equal-height positioning blocks are used to clamp the stainless steel pipe at the position to be processed, and two auxiliary bearing blocks are used to clamp the two ends of the stainless steel pipe.

[0013] The distance between the two equal-height positioning blocks is 20-50mm;

[0014] The inner axis of the stainless steel tube is aligned with the inner center line of the discharge end by adjusting the positions of the level positioning block and the auxiliary bearing block.

[0015] Based on the above method, a further improvement is made to use a drive component to drive the tool electrode to make an eccentric motion.

[0016] Among them, the non-electrical parameters satisfy:

[0017] The oscillation speed of the drive component is 0.4 to 0.6 rpm, the machining gap is 10 to 50 μm, and the machining speed is 0.02 to 0.045 g / min.

[0018] Based on further improvements to the above method, during the eccentric motion of the tool electrode, the unilateral feed rate O1O2 satisfies:

[0019] O1O2=S1+(H1-H2)-S2

[0020] Where H1 is the wall thickness of the stainless steel tube; H2 is the wall thickness of the fracture groove; S1 is the distance between the discharge end of the tool electrode and the outer end face of the stainless steel tube before processing; and S2 is the processing gap.

[0021] The distance S1 between the discharge end of the tool electrode and the outer end face of the stainless steel tube satisfies:

[0022]

[0023] Among them, S 11 S 12 S 13 S 14 The actual clearance value between four points selected on the annular discharge end of the tool electrode and the outer end face of the stainless steel tube is given. These four points are evenly distributed on the annular discharge end.

[0024] Based on further improvements to the above method, the electrical parameters satisfy the following during processing:

[0025] Pulse width 30-60μs, pulse interval 20-30μs, average machining current 0.8-2A, average machining voltage 30-60V.

[0026] Based on further improvements to the above method, during processing, in any direction, the center of the discharge end of the tool electrode deviates from the central axis of the inner cavity of the stainless steel tube along a straight line. When the deviation distance reaches O1O2, the discharge end of the tool electrode then makes an eccentric movement around the central axis of the inner cavity of the stainless steel tube.

[0027] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0028] 1. This invention abandons the traditional turning process for ultra-thin stainless steel tubes. It uses the working end of the tool electrode to discharge and erode the metal on the surface of the ultra-thin stainless steel tube to perform the fracture groove processing. That is, during the processing, the tool electrode does not come into contact with the surface of the ultra-thin stainless steel tube, so it will not cause deformation and overcomes the problem of damage to the ultra-thin stainless steel tube by cutting force.

[0029] 2. This invention utilizes the eccentric movement of the discharge end of the tool electrode around the central axis of the inner cavity of the ultra-thin stainless steel tube to process the fracture groove of the ultra-thin stainless steel tube. That is, during the processing, the ultra-thin stainless steel tube does not need to rotate, and a ring-shaped fracture groove can be processed on its outer surface. This overcomes the problem that the coaxiality of the ultra-thin stainless steel tube deteriorates during rotation, which affects the processing accuracy.

[0030] 3. During processing, simply place the ultra-thin stainless steel tube in the V-shaped groove on the level positioning block and auxiliary bearing block, and use the clamping plate to limit the upper surface of the ultra-thin stainless steel tube to achieve clamping and positioning of the ultra-thin stainless steel tube. The clamping is convenient and can ensure the stability of the ultra-thin stainless steel tube during the processing.

[0031] 4. The discharge end of the tool electrode of the present invention is annular and moves eccentrically on the outer end face of the ultra-thin stainless steel tube. During this process, the distance between the end face of the discharge end and the end face to be processed of the ultra-thin stainless steel tube is constantly changing. The closer end is the working end, and the farther end is the non-working end. In this way, the outer end face of the ultra-thin stainless steel tube is subjected to electrical discharge machining through the working end. That is, along the processing direction, the position of the working end on the inner circular end face of the discharge end is constantly changing. When the inner circular end face of the discharge end is close to the outer end face of the ultra-thin stainless steel tube, the end face of the discharge end is the working end. When the end face is far away from the outer end face of the ultra-thin stainless steel tube, the end face becomes the non-working end. This realizes the dynamic transformation between the working end and the non-working end, thereby avoiding the working end of the tool electrode being in a continuous processing state, greatly reducing the wear of the working end of the tool electrode, achieving a tool electrode wear of ≤1%, and further reducing the deformation of the working end face of the tool electrode, thereby improving the accuracy of processing the fracture groove of the ultra-thin stainless steel tube.

[0032] 5. The tool electrode of the present invention can complete the processing of the fracture groove of the ultra-thin stainless steel tube by eccentrically moving around the central axis of the inner cavity of the ultra-thin stainless steel tube for one revolution, realizing one-time processing and significantly improving processing efficiency.

[0033] 6. By eccentrically moving the tool electrode around the central axis of the inner cavity of the stainless steel tube, the single-sided feed amount of each end face at the discharge end can be made the same, ensuring the consistency of the processing depth of the break groove, thereby improving the processing accuracy of the break groove.

[0034] 7. The discharge end of the tool electrode has the same shape as the breakage groove, that is, the discharge end is convex and the breakage groove is concave. The cross-sectional dimensions of the convex shape are the same as the cross-sectional shape of the concave shape. Thus, after the tool electrode moves eccentrically around the central axis of the inner cavity of the ultra-thin stainless steel tube for one revolution, the depth and angle of the processed breakage groove are the required depth and angle of the breakage groove, and the processing accuracy is significantly improved.

[0035] 8. By adjusting the value of the single-sided feed, it is possible to process fracture grooves with different wall thicknesses. By adjusting the shape of the discharge end of the tool electrode, it is possible to process dimensions with different bevel angles α, laying the foundation for rapid production and mass production of products.

[0036] 9. The discharge end of the tool electrode of the present invention is fitted onto an ultra-thin stainless steel tube and moves eccentrically. During processing, the distance between the discharge end and the ultra-thin stainless steel tube decreases and then increases. During the process of decreasing distance, metal debris is generated between the discharge end and the stainless steel tube. At this time, some of the metal debris will be discharged with the working fluid through the processing gap. During the process of increasing distance, the distance between the discharge end and the stainless steel tube can increase by nearly 200 times, which significantly improves the efficiency of metal debris discharge. This avoids the accumulation of metal debris at the discharge end due to untimely discharge, thereby reducing the wear of the tool electrode and avoiding the risk of short circuit caused by the tool electrode directly connecting to the stainless steel tube through metal debris.

[0037] 10. By using the discharge end of the tool electrode to make an eccentric movement on the ultra-thin stainless steel tube, metal chips can be efficiently discharged, thereby enabling electrical discharge machining with a smaller machining gap. This reduces the machining current and voltage, lowers machining costs, and produces fracture grooves with low surface roughness.

[0038] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0039] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0040] Figure 1 This is a flowchart of the electrical discharge machining method for the ultra-slender stainless steel tube fracture groove of the present invention.

[0041] Figure 2 This is a schematic diagram of the tool electrode structure of the present invention;

[0042] Figure 3 for Figure 2 Schematic diagram of the cross-section at point AA;

[0043] Figure 4 for Figure 2 Schematic diagram of the cross-section at point BB;

[0044] Figure 5 This is a schematic diagram of the structure when the center line of the discharge end of the tool electrode of the present invention coincides with the central axis of the inner cavity of the stainless steel tube;

[0045] Figure 6 This is a schematic diagram of the structure when the center line of the tool electrode of the present invention deviates from the central axis of the inner cavity of the stainless steel tube;

[0046] Figure 7 This is a cross-sectional schematic diagram of the discharge end of the tool electrode of the present invention when it is fitted onto a stainless steel tube.

[0047] Figure 8 This is a schematic diagram of the trajectory of the center point O2 of the discharge end when the discharge end of the tool electrode moves eccentrically around the central axis of the inner cavity of the stainless steel tube in this invention.

[0048] Figure 9 This is a schematic diagram of the motion trajectory of any point O3 on the discharge end of the tool electrode when it moves eccentrically around the central axis of the inner cavity of the stainless steel tube in this invention.

[0049] Figure 10 This is a schematic diagram of the stainless steel pipe breakage groove in this invention;

[0050] Figure 11 This is a schematic diagram of the structure of the load-bearing component and the stainless steel tube of the present invention.

[0051] Figure 12 This is a schematic diagram of the structure of the equal-height positioning block, clamping plate and stainless steel tube in this invention.

[0052] Figure 13 This is a schematic diagram of the auxiliary support block and the stainless steel pipe working together in this invention;

[0053] Figure 14 This is a schematic diagram of the actual product after the stainless steel pipe fracture groove has been processed in this invention.

[0054] Figure label:

[0055] 1-Tool electrode; 101-Discharge end; 102-Working end; 103-Non-working end; 104-Conductive end; 2-Transmission rod; 3-Equal height positioning block; 4-Auxiliary bearing block; 5-Clamping plate; 6-Stainless steel tube; 601-Break groove; 7-Machining direction; 8-Eccentric motion direction; 9-Machine tool worktable; H1-Wall thickness of stainless steel tube; H2-Wall thickness of break groove; α-Break groove angle; S 11 S 12 S 13 S 14 - The actual clearance values ​​between four points selected on the circular working end of the tool electrode and the outer end face of the stainless steel tube; S2 - Machining clearance; O1 - Center point of the discharge end; O2 - Center point of the inner cavity of the stainless steel tube; O3 - Point selected on the discharge end. Detailed Implementation

[0056] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0057] A diameter-to-length ratio of 1:100 to 150 generally qualifies as an ultra-slender shaft. For example, a stainless steel tube used in a certain aircraft product has an outer diameter of 2mm, an inner diameter of 1mm, and a length of 1 to 1.2m. This stainless steel tube has an outer diameter-to-length ratio of 1:500 to 600, classifying it as an ultra-slender stainless steel tube. During processing, a break-off groove is typically machined into the ultra-slender steel tube. The purpose of this break-off groove is to separate the aircraft product's guidance system from the fairing when the product reaches a predetermined altitude and position.

[0058] Because ultra-thin stainless steel tubes have small diameters and thin walls, and the wall thickness at the break groove location is even thinner (e.g., 0.3±0.05mm), it is impossible to determine their critical dimensions through direct measurement. When machining a break groove at a certain location on an ultra-thin stainless steel tube, it is difficult to guarantee the wall thickness at the break groove location using traditional turning methods. This is because the excessive length will result in a greater centrifugal force during the rotation of the workpiece, leading to poorer coaxiality of the workpiece, and the resulting cutting force can easily cause deformation of the ultra-thin stainless steel tube.

[0059] To solve the above problems, the present invention provides an electrical discharge machining method for a broken groove in an ultra-thin stainless steel tube, which includes using the working state of multiple electrical discharge machining points arranged around the stainless steel tube 6 by the tool electrode 1 to realize the machining of the broken groove 601 on the surface to be machined.

[0060] Specifically, by changing the distance between the electrical discharge machining point and the surface to be machined, the same electrical discharge machining point can be in a working state or a non-working state.

[0061] Among them, when the distance between the EDM point and the surface to be processed is greater than the threshold, the EDM point is in a non-working state.

[0062] When the distance between the EDM point and the surface to be processed is less than or equal to the threshold, the EDM point is in working state.

[0063] The above threshold is the discharge distance between the EDM point that meets the processing requirements and the surface to be processed.

[0064] It is understandable that the discharge end 101 includes multiple electrical discharge machining points arranged around the circumference of the stainless steel tube. These multiple electrical discharge machining points can be continuously and uninterruptedly distributed around the circumference of the stainless steel tube, or they can be discontinuously distributed around the circumference of the stainless steel tube, as long as they can achieve continuous processing and forming of the fracture groove on the surface to be processed.

[0065] In one possible implementation, one end of the tool electrode 1 is annular, meaning that multiple electrical discharge machining points arranged circumferentially around the stainless steel tube form a continuous annular shape, such as... Figure 2-7 As shown, the inner circle of the ring matches the shape of the break groove 601, that is, the inner circle is convex and the break groove 601 is concave. The cross-sectional dimensions of the convex shape are the same as the cross-sectional shape of the concave shape. The other end of the tool electrode 1 is a conductive end 104, which is electrically connected to an output end of a power supply device installed on the machine tool to introduce current and transmit the current to the inner circle. At this time, the inner circle is a discharge end 101, so that the break groove on the surface to be processed can be realized through the working state of multiple electrical discharge machining points arranged around the stainless steel tube through the discharge end 101.

[0066] In one possible implementation, the discharge end is a rigid structure, with the discharge end 101 fitted onto the outer end face of the stainless steel tube 6. During processing, the stainless steel tube 6 is electrically connected to another output end of the power supply device, and the tool electrode 1 moves eccentrically around the central axis of the inner cavity of the stainless steel tube 6. During the eccentric movement of the tool electrode 1, the distance between the inner circular end face of the discharge end 101 and the end face of the stainless steel tube 6 to be processed continuously changes. When the distance between the electrical discharge machining point and the surface to be processed is greater than a threshold, the electrical discharge machining point is in a non-working state; at this time, the electrical discharge machining point is the non-working end 103. When the distance between the electrical discharge machining point and the surface to be processed is less than or equal to a threshold, the electrical discharge machining point is in a non-working state. When the threshold is reached, the electrical discharge machining (EDM) point is in the working state. At this time, the EDM point is the working end 102. In this way, the transition between the working state and the non-working state is realized at the same EDM point. The working states of all EDM points together realize the machining of the fracture groove on the surface to be machined. That is to say, the position of the working end 102 is constantly changing within the inner circular end face of the discharge end 101. The circular discharge end of the tool electrode moves eccentrically around the central axis of the inner cavity of the stainless steel tube. All the working ends form a continuous circular discharge end around the circumference of the stainless steel tube. In this way, the discharge end 101 of the tool electrode 1 is avoided from being in a continuous machining state, thereby reducing the wear of the tool electrode 1.

[0067] Among them, the annular discharge end 101 of the tool electrode 1 includes several working ends 102 distributed in a ring. When the discharge end moves eccentrically around the central axis of the inner cavity of the stainless steel tube 6 for processing, the several working ends 102 are in a non-synchronous and non-continuous processing state; and the processing trajectory of the several working ends together constitutes the break groove of the stainless steel tube 6.

[0068] In this process, after the tool electrode 1 completes one eccentric movement, all end faces of the discharge end 101 participate in electrical discharge machining. That is, all working ends 102 constitute a complete discharge end 101, and the machining trajectories of all working ends 102 together form the ultra-slender stainless steel tube breakage groove 601. Along the machining direction 7, the working ends 102 exhibit a "circular motion" phenomenon on the discharge end 101. That is, the position of the working ends 102 is different at different times. In this way, all working ends 102 are processed alternately and in an orderly manner. The machining direction 7 is the circumferential direction around the outer end face of the stainless steel tube 6, and the plane containing this circumferential direction is perpendicular to the central axis of the inner cavity of the stainless steel tube 6.

[0069] Compared with the prior art, in the present invention, the tool electrode 1 does not contact the surface of the stainless steel tube 6 during processing, thus preventing deformation. Furthermore, the stainless steel tube 6 does not need to move during processing, allowing the ring-shaped break groove 601 to be machined on its outer surface. This overcomes the problem of decreased coaxiality of the stainless steel tube 6 during rotation, which affects processing accuracy. Additionally, the tool electrode 1 completes the processing of the break groove 601 by eccentrically moving around the central axis of the inner cavity of the stainless steel tube 6 in one revolution, achieving one-time processing and significantly improving processing efficiency. Moreover, the discharge end 101 of the tool electrode 1 is annular, and it moves eccentrically around the outer end face of the stainless steel tube 6. During this process, the distance between the end face of the discharge end 101 and the end face of the stainless steel tube 6 to be processed continuously changes, with the working end 102 being closer and the distance between the working end 102 and the end face of the stainless steel tube 6 being further apart. The end farther away is the non-working end 103, and the outer end face of the stainless steel tube 6 is subjected to electrical discharge machining through the working end 102. Along the machining direction, the position of the working end 102 changes continuously within the inner circle end face of the discharge end 101. That is, when the inner circle end face of the discharge end 101 is close to the outer end face of the stainless steel tube 6, the end face of the discharge end 101 is the working end 102. When the end face is far away from the outer end face of the stainless steel tube 6, the end face becomes the non-working end 103. This realizes the dynamic transformation between the working end 102 and the non-working end 103, thereby avoiding the working end 102 of the tool electrode 1 being in a continuous machining state, greatly reducing the wear of the working end of the tool electrode 1, achieving a tool electrode wear of ≤1%, and thus reducing the deformation of the working end face of the tool electrode 1, thereby improving the machining accuracy of the ultra-thin stainless steel tube break groove 601.

[0070] The criterion for determining whether the discharge end 101 is the working end 102 is whether the distance between the discharge end 101 and the surface to be processed of the stainless steel tube 6 is greater than 50μm. If not, the discharge end 101 is the working end 102; if so, the discharge end 101 is the non-working end 103.

[0071] Specifically, the tool electrode 1 is mounted on a machine tool. During machining, the machine tool drives the tool electrode 1 to make an eccentric motion, thereby enabling the discharge end 101 of the tool electrode to perform electrical discharge machining around the end face of the stainless steel tube 6. The machining direction 7 is a circumferential direction around the outer end face of the stainless steel tube 6, and the center line of this circumferential direction coincides with the central axis of the inner cavity of the stainless steel tube 6.

[0072] Specifically, before the tool electrode 1 makes an eccentric movement, it is necessary to adjust the center of the inner circle of the discharge end 101 of the tool electrode 1 to coincide with the central axis of the stainless steel tube 6, and there should be a margin gap between the discharge end 101 and the outer end face of the stainless steel tube 6. That is, the diameter of the inner circle of the discharge end 101 is larger than the outer diameter of the stainless steel tube 6. For example, the diameter of the inner circle is 10 to 20 mm, which is 5 to 10 times the outer diameter of the stainless steel tube 6. In this way, it is easy to determine the value of the single-sided feed rate O1O2 during the electrical discharge machining process.

[0073] Among them, the unilateral feed rate O1O2 satisfies:

[0074] O1O2=S1+(H1-H2)-S2

[0075] Where O1 represents the center point of the discharge terminal 101 of the tool electrode 1;

[0076] O2 indicates the center point of the inner cavity of the stainless steel pipe 6;

[0077] H1 is the wall thickness of stainless steel pipe 6;

[0078] H2 is the wall thickness of the fracture groove 601;

[0079] S1 indicates that there is a margin gap between the discharge terminal 101 and the outer end face of the stainless steel tube 6.

[0080] S2 is the machining clearance, which refers to the closest distance between the working end 102 and the end face of the stainless steel tube 601 when the tool electrode 1 moves eccentrically.

[0081] Wherein, S1 satisfies:

[0082]

[0083] Among them, such as Figure 5 As shown, S 11 S 12 S 13 S 14 The actual clearance value between four points selected on the discharge end 101 of the tool electrode 1 and the outer end face of the stainless steel tube 6 is given. These four points are evenly distributed on the discharge end 101.

[0084] For example, S 11 S 12 S 13 S 14 The corresponding values ​​are 2.055mm, 2.060mm, 2.065mm, and 2.050mm, respectively. At this time, S1 = 2.058mm.

[0085] The machining gap S2 is set to 10-50 μm to meet the requirements of electrical discharge machining.

[0086] For example, S2 = 10 μm; H1 = 0.5 mm, H2 = 0.3 mm, S1 = 2.058 mm, and O1O2 = 2.248 mm.

[0087] Among them, the automatic centering module on the machine tool can be used to measure S. 11 S 12 S 13 S 14 If the four values ​​are equal, the center of the inner circle of the discharge end 101 of the tool electrode 1 coincides with the central axis of the inner cavity of the stainless steel tube 6.

[0088] Among them, after the center of the discharge end 101 of the machine tool adjustment tool electrode 1 is aligned with the central axis of the inner cavity of the stainless steel tube 6, the actual measured S 11 S 12 S 13 S 14 The closer the four values ​​are, the more accurate the value of S1 will be, and the more accurate the single-sided feed amount O1O2 will be. In this way, the accuracy of the machining gap can be ensured during the eccentric movement of the tool electrode 1, thereby ensuring the machining depth of the working end 102 and ensuring the dimensional accuracy of the machined break groove 601.

[0089] Specifically, after the center of the discharge end 101 of the adjustment tool electrode 1 is aligned with the central axis of the inner cavity of the stainless steel tube 6, the machine tool drives the tool electrode 1 to make an eccentric movement. The detailed process is as follows.

[0090] The movement trajectories of the center point O1 of the discharge terminal 101 of the tool electrode 1 and the center point O2 of the inner cavity of the stainless steel tube 6 are described below:

[0091] Move tool electrode 1 so that O1 is away from O2. The moving distance is the same as the unilateral feed amount O1O2. At this time, the distance between O1 and O2 is O1O2.

[0092] With O2 as the center and O1O2 as the radius, rotate O1 around O2. The trajectory of O1's movement will then be a circle, as shown below. Figure 8 As shown, the center of the circle is O2, and the radius is O1O2;

[0093] During the movement of O1, when the closest distance between the end face of the discharge end 101 and the surface of the stainless steel tube 6 reaches 10μm, the power supply device is turned on to deliver a pulse voltage to the tool electrode 1 and the stainless steel tube 6, and the metal on the surface of the stainless steel tube 6 is etched at a processing speed of 0.04g / min until the distance between O1 and O2 is O1O2, and then O1 moves in a circular motion around O2.

[0094] To further illustrate the motion trajectory of tool electrode 1, an arbitrary point O3 on discharge terminal 101 is selected, and the trajectory of O3 is used for illustration, as follows:

[0095] Move tool electrode 1 so that O3 moves toward O2, and the moving distance is O1O2;

[0096] When O1 rotates around O2, at this time, as Figure 9 As shown, the trajectory of O3 is a circle with the initial position of O3 as the center and O1O2 as the radius;

[0097] During the movement of O3, when the closest distance between the end face of the discharge end 101 and the surface of the stainless steel tube 6 reaches 10μm, the power supply device is turned on to deliver a pulse voltage to the tool electrode 1 and the stainless steel tube 6, and the metal on the surface of the stainless steel tube 6 is etched at a processing speed of 0.04g / min until the moving distance of O3 reaches O1O2. Then, O3 moves in a circle with its initial position as the center.

[0098] Thus, during the eccentric movement of the tool electrode 1, the distance between the inner circular end face of the discharge end 101 and the outer surface of the stainless steel tube 6 changes continuously. The distance between each part of the inner circular end face of the discharge end 101 and the outer end face of the stainless steel tube 6 changes from close to far away. Consequently, the discharge end 101 changes from the working state to the non-working state, that is, the dynamic transformation between the working end 102 and the non-working end 103 is realized.

[0099] The discharge end 101 has a clearance between itself and the outer end face of the stainless steel tube 601 to ensure that the non-working end 103 at the discharge end 101 and the end face of the stainless steel tube 6 have a sufficiently large non-processing clearance, thereby ensuring that the pulse voltage released at the non-working end 103 cannot erode the metal on the surface of the stainless steel tube 6. Thus, when the tool electrode 1 moves eccentrically, the working end 102 and the non-working end 103 can be dynamically switched.

[0100] The conductive end 104 of the tool electrode 1 is electrically connected to one output end of the power supply device installed on the machine tool, and the stainless steel tube 6 is electrically connected to the other output end of the power supply device. The power supply device includes a pulse power supply, and its two output ends are respectively connected to the positive and negative terminals of the pulse power supply to output pulse voltage.

[0101] During processing, the stainless steel tube 6 and the discharge end 101 of the tool electrode 1 are immersed in a liquid medium with a certain degree of insulation, for example, kerosene, mineral oil, or deionized water; when a pulse voltage is applied to the discharge end 101 and the stainless steel tube 6, the liquid medium at the closest point between the stainless steel tube 6 and the discharge end 101 under the given conditions is broken down, forming a discharge channel. Due to the very small cross-sectional area of ​​the channel and the extremely short discharge time, the energy is highly concentrated (10). 6 W / cm2 The instantaneous high temperature generated in the discharge area is sufficient to melt or even evaporate the metal on the surface of the stainless steel tube 6, resulting in a small pit. After the first pulse discharge ends, after a very short interval, the second pulse discharges at the closest point between the other electrodes. This process continues at a high frequency, and the tool electrode 1 continuously feeds into the stainless steel tube 6. Its shape is eventually replicated on the stainless steel tube 6, forming the required machining surface. During the machining process, although a small portion of the total energy is released onto the tool electrode 1, causing wear on the tool electrode 1, the working end 102 at the discharge end 101 is constantly changing position due to the eccentric movement of the discharge end 101 around the central axis of the inner cavity of the stainless steel tube 6. This reduces wear on the tool electrode 1 by avoiding continuous machining of the working end 102. Consequently, at each moment of machining, the working end 102 of the discharge end 101 maintains a relatively complete shape, improving machining accuracy.

[0102] For example, during the processing, the electrical parameters satisfy:

[0103] Pulse width 30-60μs, pulse interval 20-30μs, average machining current 0.8-2A, average machining voltage 30-60V.

[0104] Specifically, during processing, the tool electrode 1 is eccentrically moved by the machine tool control, while the stainless steel tube 6 remains stationary.

[0105] The tool electrode 1 is connected to a drive device installed on the machine tool. The drive device includes a transmission rod 2. During processing, the machine tool controls the transmission rod 2 to swing, thereby driving the tool electrode 1 to make an eccentric motion through the transmission rod 2.

[0106] Specifically, the transmission rod 2 swings clockwise within the swing plane ZY, which is parallel to the plane where the discharge end 101 is located. In this way, the tool electrode 1 achieves eccentric movement around the central axis of the inner cavity of the stainless steel tube 6.

[0107] For example, during the processing, the non-electrical parameters satisfy:

[0108] The swing speed of the transmission rod 2 is 0.4 to 0.6 rpm, the machining gap is 10 to 50 μm, the machining speed is 0.02 to 0.045 g / min, and the single-sided feed rate is 2.214 to 2.2316 mm.

[0109] Specifically, the stainless steel tube 6 is clamped using a load-bearing component to ensure processing accuracy.

[0110] Among them, such as Figure 10-13As shown, the bearing assembly includes a height positioning block 3 and an auxiliary bearing block 4 mounted on the machine tool; the stainless steel pipe 6 is placed on the height positioning block 3 and the auxiliary bearing block 4 to clamp the stainless steel pipe 6.

[0111] Specifically, two equal-height positioning blocks 3 are provided, which are located on both sides of the position to be processed on the stainless steel tube 6, to ensure the stability of the position to be processed on the stainless steel tube 6 during processing. For example, the distance between the two equal-height positioning blocks 3 is 30mm.

[0112] Specifically, two auxiliary support blocks 4 are provided, and two equal-height positioning blocks 3 are located between the two auxiliary support blocks 4, so as to support and position the two ends of the stainless steel pipe 6 through the two auxiliary support blocks 4, and further ensure the stability of the stainless steel pipe 6 during the processing.

[0113] The upper surfaces of the equal-height positioning block 3 and the auxiliary bearing block 4 are flush, and a V-shaped groove is provided on the upper surfaces of the equal-height positioning block 3 and the auxiliary bearing block 4. The stainless steel pipe 6 is placed in the V-shaped groove to limit the movement of the stainless steel pipe 6.

[0114] Furthermore, a clamping plate 5 is provided on the leveling positioning block 3. The clamping plate 5 covers the V-groove and is engaged with the leveling positioning block 3 to limit the movement of the stainless steel tube 6 and further improve the stability of the stainless steel tube 6. For example, the angle of the V-groove is 60°-90° and the depth is 5-10mm.

[0115] Before placing the stainless steel tube 6 on the leveling block 3, the tool electrode 1 needs to be aligned using a machine tool. Then, the stainless steel tube 6 is inserted into the discharge end 101 of the tool electrode 1. Finally, the stainless steel tube 6 is clamped using the leveling block 3, the auxiliary bearing block 4, and the clamping plate 5, and the leveling block 3 and the auxiliary bearing block 4 are used to align the stainless steel tube 6.

[0116] Specifically, after the tool electrode 1 is aligned, the position of the equal height positioning block 3 and the auxiliary bearing block 4 on the machine tool is adjusted using the XYZ axis of the machine tool to align the stainless steel tube 6, ensuring that the central axis of the inner cavity of the stainless steel tube 6 coincides with the center line of the discharge end 101 of the tool electrode 1, so as to determine the value of the single-sided feed amount O1O2, thereby improving the machining accuracy.

[0117] The alignment process for stainless steel pipe 6 is as follows.

[0118] First, fix two equal-height positioning blocks 3 and two auxiliary support blocks 4 on the machine tool's worktable 9. Then, use a dial indicator to align the sides of the blocks with the X-axis of the machine tool, ensuring a parallelism error of ≤0.01mm.

[0119] Before placing the stainless steel tube 6 on the leveling block 3, first insert the stainless steel tube 6 into the discharge end 101 of the tool electrode 1, and then place the stainless steel tube 6 on the leveling block 3 and the auxiliary support block 4. In this way, the leveling block 3 and the auxiliary support block 4 are used to align the stainless steel tube 6.

[0120] One end of the transmission rod 2 is connected to the tool electrode 1 and is parallel to the center line of the discharge end 101 of the tool electrode 1. During the processing, the other end of the transmission rod 2 is mounted on the machine tool so that the machine tool drives the transmission rod 2 to swing, and then drives the tool electrode 1 to move through the transmission rod 2, so that the discharge end 101 of the tool electrode 1 can make an eccentric movement around the central axis of the inner cavity of the stainless steel tube 6.

[0121] In this way, the discharge end 101 of the tool electrode 1 moves eccentrically around the central axis of the inner cavity of the stainless steel tube 6 for one revolution, which can complete the processing of the stainless steel tube break groove 601, achieving one-time processing and significantly improving processing efficiency.

[0122] In order to better utilize the above processing method to process the stainless steel pipe break groove 601, the present invention also provides a processing device, including a tool electrode 1 installed on a machine tool, a bearing component for clamping the stainless steel pipe 6, and a drive component for controlling the movement state of the tool electrode 1.

[0123] Among them, one end of the tool electrode 1 is the discharge end 101, and the discharge end 101 includes multiple electrical discharge machining points arranged circumferentially around the stainless steel tube 6. The same electrical discharge machining point includes a working state and a non-working state.

[0124] When the distance between the EDM point and the surface to be processed is greater than the threshold, the EDM point is in a non-working state.

[0125] When the distance between the EDM point and the surface to be processed is less than or equal to the threshold, the EDM point is in working state.

[0126] The above threshold is the discharge distance between the EDM point that meets the processing requirements and the surface to be processed. For example, this distance is 0-50μm.

[0127] Among them, the working state of multiple electrical discharge machining points arranged around the stainless steel tube in six directions realizes the processing of the break groove 601 on the surface to be processed.

[0128] It is understandable that the discharge end 101 includes multiple electrical discharge machining points arranged around the circumference of the stainless steel tube. These multiple electrical discharge machining points can be continuously and uninterruptedly distributed around the circumference of the stainless steel tube, or they can be discontinuously distributed around the circumference of the stainless steel tube, as long as they can achieve continuous processing and forming of the fracture groove on the surface to be processed.

[0129] In one possible implementation, one end of the tool electrode 1 is annular, meaning that multiple electrical discharge machining points arranged around the circumference of the stainless steel tube form a continuous annular shape. The inner end of the annular shape matches the shape of the break groove 601, i.e., the inner end is convex and the break groove 601 is concave. The cross-sectional dimensions of the convex shape are the same as the cross-sectional shape of the concave shape. The other end of the tool electrode 1 is a conductive end 104, which is electrically connected to an output end of a power supply device installed on the machine tool to introduce current and transmit the current to the inner end. At this time, the inner end is a discharge end 101, so that the break groove on the surface to be processed can be processed through the working state of the multiple electrical discharge machining points arranged around the circumference of the stainless steel tube via the discharge end 101.

[0130] In one possible implementation, the discharge end is a rigid structure, with the discharge end 101 fitted onto the outer end face of the stainless steel tube 6. During processing, the stainless steel tube 6 is electrically connected to another output end of the power supply device, and the tool electrode 1 moves eccentrically around the central axis of the inner cavity of the stainless steel tube 6. During the eccentric movement of the tool electrode 1, the distance between the inner circular end face of the discharge end 101 and the end face of the stainless steel tube 6 to be processed continuously changes. When the distance between the electrical discharge machining point and the surface to be processed is greater than a threshold, the electrical discharge machining point is in a non-working state; at this time, the electrical discharge machining point is the non-working end 103. When the distance between the electrical discharge machining point and the surface to be processed is less than or equal to a threshold, the electrical discharge machining point is in a non-working state. When the threshold is reached, the electrical discharge machining (EDM) point is in the working state. At this time, the EDM point is the working end 102. In this way, the transition between the working state and the non-working state is realized at the same EDM point. The working states of all EDM points together realize the machining of the fracture groove on the surface to be machined. That is to say, the position of the working end 102 is constantly changing within the inner circular end face of the discharge end 101. The circular discharge end of the tool electrode moves eccentrically around the central axis of the inner cavity of the stainless steel tube. All the working ends form a continuous circular discharge end around the circumference of the stainless steel tube. In this way, the discharge end 101 of the tool electrode 1 is avoided from being in a continuous machining state, thereby reducing the wear of the tool electrode 1.

[0131] Among them, the annular discharge end 101 of the tool electrode 1 includes several working ends 102 distributed in a ring. When the discharge end moves eccentrically around the central axis of the inner cavity of the stainless steel tube 6 for processing, the several working ends 102 are in a non-synchronous and non-continuous processing state; and the processing trajectory of the several working ends together constitutes the break groove of the stainless steel tube 6.

[0132] In this process, after the tool electrode 1 completes one eccentric movement, all end faces of the discharge end 101 participate in electrical discharge machining. That is, all working ends 102 constitute a complete discharge end 101, and the machining trajectories of all working ends 102 together form the ultra-slender stainless steel tube breakage groove 601. Along the machining direction 7, the working ends 102 exhibit a "circular motion" phenomenon on the discharge end 101. That is, the position of the working ends 102 is different at different times. In this way, all working ends 102 are processed alternately and in an orderly manner. The machining direction 7 is the circumferential direction around the outer end face of the stainless steel tube 6, and the plane containing this circumferential direction is perpendicular to the central axis of the inner cavity of the stainless steel tube 6.

[0133] Specifically, one end of the tool electrode 1 is mounted on a machine tool, and the discharge end 101 of the tool electrode 1 is fitted onto the outer end face of the stainless steel tube 6. The center of the inner circle of the discharge end 101 of the tool electrode 1 coincides with the central axis of the inner cavity of the stainless steel tube 6, and there is a clearance between the discharge end 101 and the outer end face of the stainless steel tube 6. That is, the diameter of the inner circle of the discharge end 101 is larger than the outer diameter of the stainless steel tube 6. For example, the diameter of the inner circle is 10-20 mm, which is 5-10 times the outer diameter of the stainless steel tube 6. This facilitates the determination of the single-sided feed rate O1O2 during the electrical discharge machining process. During machining, the tool electrode 1 is oscillated by the machine tool. At this time, the discharge end 101 of the tool electrode 1 is in an eccentric motion state around the central axis of the inner cavity of the stainless steel tube 6.

[0134] Among them, the unilateral feed rate O1O2 satisfies:

[0135] O1O2=S1+(H1-H2)-S2

[0136] Where O1 represents the center point of the discharge terminal 101 of the tool electrode;

[0137] O2 indicates the center point of the inner cavity of the stainless steel pipe 6;

[0138] H1 is the wall thickness of stainless steel pipe 6;

[0139] H2 is the wall thickness of the fracture groove 601;

[0140] S2 is the machining clearance, which refers to the closest distance between the working end 102 and the end face of the stainless steel tube 601 when the tool electrode 1 moves eccentrically.

[0141] S1 indicates that there is a margin gap between the discharge end 101 and the outer end face of the stainless steel tube 6.

[0142] Wherein, S1 satisfies:

[0143]

[0144] Among them, S 11 S 12 S13 S 14 The actual clearance value between four points selected on the discharge end 101 of the tool electrode and the outer end face of the stainless steel tube 6 is given. These four points are evenly distributed on the discharge end 101.

[0145] For example, S 11 S 12 S 13 S 14 The corresponding values ​​are 2.055mm, 2.060mm, 2.065mm, and 2.050mm, respectively. At this time, S1 = 2.058mm.

[0146] The machining gap S2 is set to 10-50 μm to meet the requirements of electrical discharge machining.

[0147] For example, S2 = 10 μm; H1 = 0.5 mm, H2 = 0.3 mm, S1 = 2.058 mm, and O1O2 = 2.248 mm.

[0148] Among them, the automatic centering module on the machine tool can be used to measure S. 11 S 12 S 13 S 14 If the four values ​​are equal, the center of the inner circle of the discharge end 101 of the tool electrode 1 coincides with the central axis of the inner cavity of the stainless steel tube 6.

[0149] Among them, after the center of the discharge end 101 of the machine tool adjustment tool electrode 1 is aligned with the central axis of the inner cavity of the stainless steel tube 6, the actual measured S 11 S 12 S 13 S 14 The closer the four values ​​are, the more accurate the value of S1 will be, and the more accurate the single-sided feed amount O1O2 will be. In this way, the accuracy of the machining gap can be ensured during the eccentric movement of the tool electrode 1, thereby ensuring the machining depth of the working end 101 and ensuring the dimensional accuracy of the machined break groove 601.

[0150] In this process, after the center of the discharge end 101 of the adjustment tool electrode 1 coincides with the central axis of the inner cavity of the stainless steel tube 6, the tool electrode 1 is in an eccentric motion state under the action of the machine tool. The detailed process is as follows.

[0151] The movement trajectories of the center point O1 of the discharge terminal 101 of the tool electrode 1 and the center point O2 of the inner cavity of the stainless steel tube 6 are described below:

[0152] Move tool electrode 1 so that O1 is away from O2. The moving distance is the same as the unilateral feed amount O1O2. At this time, the distance between O1 and O2 is O1O2.

[0153] With O2 as the center and O1O2 as the radius, rotate O1 around O2. At this time, the trajectory of O1 is a circle with O2 as the center and O1O2 as the radius.

[0154] During the movement of O1, when the closest distance between the end face of the discharge end 101 and the surface of the stainless steel tube 6 reaches 10μm, the power supply device is turned on to deliver a pulse voltage to the tool electrode 1 and the stainless steel tube 6, and the metal on the surface of the stainless steel tube 6 is etched at a processing speed of 0.04g / min until the distance between O1 and O2 is O1O2, and then O1 moves in a circular motion around O2.

[0155] To further illustrate the motion trajectory of tool electrode 1, an arbitrary point O3 on discharge terminal 101 is selected, and the trajectory of O3 is used for illustration, as follows:

[0156] Move tool electrode 1 so that O3 moves toward O2, and the moving distance is O1O2;

[0157] When O1 rotates around O2, the trajectory of O3 is a circle with the initial position of O3 as the center and O1O2 as the radius.

[0158] During the movement of O3, when the closest distance between the end face of the discharge end 101 and the surface of the stainless steel tube 6 reaches 10μm, the power supply device is turned on to deliver a pulse voltage to the tool electrode 1 and the stainless steel tube 6, and the metal on the surface of the stainless steel tube 6 is etched at a processing speed of 0.04g / min until the moving distance of O3 reaches O1O2. Then, O3 moves in a circle with its initial position as the center.

[0159] Thus, during the eccentric movement of the tool electrode 1, the distance between the inner circular end face of the discharge end 101 and the outer surface of the stainless steel tube 6 changes continuously. The distance between each part of the inner circular end face of the discharge end 101 and the outer end face of the stainless steel tube 6 changes from close to far away. Consequently, the discharge end 101 changes from a working state to a non-working state, that is, the dynamic transformation between the working end 102 and the non-working end 103 is realized. In this way, the working end 102 of the tool electrode 1 is avoided from being in a continuous processing state, which greatly reduces the wear on the working end 102 of the tool electrode 1.

[0160] The discharge end 101 has a clearance S1 between itself and the outer end face of the stainless steel tube 601. This clearance ensures that the non-working end 103 at the discharge end 101 and the end face of the stainless steel tube 6 have a sufficiently large non-processing clearance, thereby ensuring that the pulse voltage released at the non-working end 103 cannot erode the metal on the surface of the stainless steel tube 6. Thus, when the tool electrode 1 moves eccentrically, the working end 102 and the non-working end 103 can be dynamically switched.

[0161] The conductive end of the tool electrode 1 is electrically connected to one output end of the power supply device installed on the machine tool, and the stainless steel tube 6 is electrically connected to the other output end of the power supply device. The power supply device includes a pulse power supply, and its two output ends are respectively connected to the positive and negative terminals of the pulse power supply to output pulse voltage.

[0162] For example, during the processing, the electrical parameters satisfy:

[0163] Pulse width 30-60μs, pulse interval 20-30μs, average machining current 0.8-2A, average machining voltage 30-60V.

[0164] Specifically, the aforementioned drive assembly includes a transmission rod 2, one end of which is connected to the tool electrode 1, and the other end of which is mounted on a machine tool. The machine tool can control the swing of the transmission rod 2, thereby causing the discharge end 101 of the tool electrode 1 to move eccentrically around the central axis of the inner cavity of the stainless steel tube 6.

[0165] Specifically, the transmission rod 2 swings clockwise within the swing plane ZY, which is parallel to the plane containing the discharge end 101. This achieves the eccentric movement of the discharge end of the tool electrode 1 around the central axis of the inner cavity of the stainless steel tube 6. During processing, the stainless steel tube 6 remains stationary.

[0166] For example, during the processing, the non-electrical parameters satisfy:

[0167] The oscillation speed of the drive component is 0.4 to 0.6 rpm, the machining gap is 10 to 50 μm, the machining speed is 0.02 to 0.045 g / min, and the single-sided feed rate is 2.214 to 2.2316 mm.

[0168] Specifically, the load-bearing components include a height positioning block 3 and an auxiliary support block 4 installed on the machine tool to place the stainless steel pipe 6 on the height positioning block 3 and the auxiliary support block 4 to clamp the stainless steel pipe 6.

[0169] Specifically, two equal-height positioning blocks 3 are provided, which are located on both sides of the position to be processed on the stainless steel tube 6, to ensure the stability of the position to be processed on the stainless steel tube 6 during processing. For example, the distance between the two equal-height positioning blocks 3 is 30mm.

[0170] Specifically, two auxiliary support blocks 4 are provided, and two equal-height positioning blocks 3 are located between the two auxiliary support blocks 4, so as to support and position the two ends of the stainless steel pipe 6 through the two auxiliary support blocks 4, and further ensure the stability of the stainless steel pipe 6 during the processing.

[0171] The upper surfaces of the equal-height positioning block 3 and the auxiliary bearing block 4 are flush, and a V-shaped groove is provided on the upper surfaces of the equal-height positioning block 3 and the auxiliary bearing block 4. The stainless steel pipe 6 is placed in the V-shaped groove to limit the movement of the stainless steel pipe 6.

[0172] Furthermore, a clamping plate 5 is provided on the leveling positioning block 3. The clamping plate 5 covers the V-groove and is engaged with the leveling positioning block 3 to limit the movement of the stainless steel tube 6 and further improve the stability of the stainless steel tube 6. For example, the angle of the V-groove is 60°-90° and the depth is 5-10mm.

[0173] Before placing the stainless steel tube 6 on the leveling block 3, the tool electrode 1 needs to be aligned first. Then, the stainless steel tube 6 is inserted into the discharge end 101 of the tool electrode 1. Finally, the stainless steel tube 6 is clamped using the leveling block 3, the auxiliary support block 4, and the clamping plate 5, and the stainless steel tube 6 is aligned using the leveling block 3 and the auxiliary support block 4.

[0174] Specifically, after the tool electrode 1 is aligned, the position of the equal height positioning block 3 and the auxiliary bearing block 4 on the machine tool is adjusted using the XYZ axis of the machine tool to align the stainless steel tube 6, ensuring that the central axis of the inner cavity of the stainless steel tube 6 coincides with the center line of the discharge end 101 of the tool electrode 1, so as to determine the value of the single-sided feed amount O1O2, thereby improving the machining accuracy.

[0175] The alignment process for stainless steel pipe 6 is as follows.

[0176] First, fix two equal-height positioning blocks 3 and two auxiliary support blocks 4 on the machine tool's worktable 9. Then, use a dial indicator to align the sides of the blocks with the X-axis of the machine tool, ensuring a parallelism error of ≤0.01mm.

[0177] One end of the transmission rod 2 is connected to the tool electrode 1 and is parallel to the center line of the discharge end 101 of the tool electrode 1. During the processing, the other end of the transmission rod 2 is mounted on the machine tool so that the machine tool drives the transmission rod 2 to swing, and then drives the tool electrode 1 to move, so as to realize that the discharge end 101 of the tool electrode 1 makes an eccentric movement around the central axis of the inner cavity of the stainless steel tube 6.

[0178] In this way, the discharge end 101 of the tool electrode 1 moves eccentrically around the central axis of the inner cavity of the stainless steel tube 6 for one revolution, which can complete the processing of the stainless steel tube break groove 601, achieving one-time processing and significantly improving processing efficiency.

[0179] Compared with the prior art, the present invention abandons the traditional turning process for ultra-thin stainless steel tubes. It uses the working end 102 of the tool electrode 1 to discharge and erode the surface metal of the ultra-thin stainless steel tube 6 to process the fracture groove 601. That is, during the processing, the tool electrode 1 does not contact the surface of the ultra-thin stainless steel tube, so it will not cause deformation and overcomes the problem of damage to the ultra-thin stainless steel tube by cutting force.

[0180] This invention utilizes the eccentric movement of the discharge end 101 of the tool electrode 1 around the central axis of the inner cavity of the ultra-thin stainless steel tube to process the break groove 601 of the ultra-thin stainless steel tube. That is, during the processing, the ultra-thin stainless steel tube does not need to move, and the ring-shaped break groove 601 can be processed on its outer surface. This overcomes the problem that the coaxiality of the ultra-thin stainless steel tube deteriorates during rotation, which affects the processing accuracy.

[0181] During processing, the ultra-thin stainless steel tube is simply placed in the V-shaped groove on the equal height positioning block 3 and the auxiliary bearing block 4, and the upper surface of the ultra-thin stainless steel tube is limited by the clamping plate 5. This allows for the clamping and positioning of the ultra-thin stainless steel tube, which is convenient and ensures the stability of the ultra-thin stainless steel tube 6 during processing.

[0182] The discharge end 101 of the tool electrode 1 of the present invention is annular and moves eccentrically around the outer end face of the ultra-thin stainless steel tube 6. During this process, the distance between the end face of the discharge end 101 and the end face to be processed of the ultra-thin stainless steel tube 6 is constantly changing. The closer end is the working end 102, and the farther end is the non-working end 103. Thus, the outer end face of the ultra-thin stainless steel tube 6 is subjected to electrical discharge machining through the working end 102. That is, along the machining direction, the position of the working end 102 on the inner circular end face of the discharge end 101 is constantly changing, that is, the inner circular end face of the discharge end 101 is closer to the ultra-thin stainless steel tube 6. When the discharge end 101 is on the outer end face of the slender stainless steel tube 6, the end face of the discharge end 101 is the working end 102. When the end face is far away from the outer end face of the ultra-slender stainless steel tube 6, the end face transforms into the non-working end 103, realizing the dynamic transformation between the working end 102 and the non-working end 103. In this way, the working end 102 of the tool electrode 1 is not in a continuous processing state, which greatly reduces the wear on the working end 102 of the tool electrode 1, achieving a tool electrode wear of ≤1%, thereby reducing the deformation of the working end face of the tool electrode 1, and thus improving the processing accuracy of the fracture groove 601 of the ultra-slender stainless steel tube.

[0183] The discharge end 101 of the tool electrode 1 of the present invention can complete the processing of the fracture groove 601 of the ultra-thin stainless steel tube by moving eccentrically around the central axis of the inner cavity of the ultra-thin stainless steel tube 6 once, thus achieving one-time processing and significantly improving processing efficiency.

[0184] By eccentrically moving the discharge end 101 of the tool electrode 1 around the central axis of the inner cavity of the stainless steel tube 6, the single-sided feed amount of each end face of the discharge end 101 can be made the same, ensuring the consistency of the processing depth of the break groove 601, thereby improving the processing accuracy of the break groove 601.

[0185] The discharge end 101 of the tool electrode 1 has the same shape as the breakage groove 601, that is, the discharge end 101 is convex and the breakage groove 601 is concave. The cross-sectional dimensions of the convex shape are the same as the cross-sectional shape of the concave shape. Thus, after the discharge end 101 of the tool electrode 1 moves eccentrically around the central axis of the inner cavity of the ultra-thin stainless steel tube 6 for one revolution, the depth and angle of the processed breakage groove 601 are the required depth and angle of the breakage groove 601, and the processing accuracy is significantly improved.

[0186] By adjusting the value of the single-sided feed, the fracture groove 601 with different wall thicknesses can be processed. By adjusting the shape of the discharge end 101 of the tool electrode 1, the size processing of different oblique angles α can be achieved, laying the foundation for rapid production and mass production of products.

[0187] The discharge end 101 of the tool electrode 1 of the present invention is fitted onto the ultra-thin stainless steel tube 6 and moves eccentrically. During processing, the distance between the discharge end 101 and the ultra-thin stainless steel tube 6 decreases and then increases. During the process of decreasing distance, metal debris is generated between the discharge end 101 and the stainless steel tube 6. At this time, some of the metal debris will be discharged through the processing gap with the working fluid. During the process of increasing distance, the distance between the discharge end 101 and the stainless steel tube 6 can increase by nearly 200 times, which significantly improves the efficiency of metal debris discharge. This avoids the accumulation of metal debris at the discharge end 101 due to untimely discharge, thereby reducing the wear of the tool electrode 1 and avoiding the risk of short circuit caused by direct connection of the tool electrode 1 to the stainless steel tube 6 through metal debris.

[0188] By having the discharge end 101 of the tool electrode 1 made eccentric motion on the ultra-thin stainless steel tube 6, metal chips can be efficiently discharged, thereby enabling electrical discharge machining with a smaller machining gap. This reduces the machining current and voltage, lowers the machining cost, and allows for the production of a fracture groove 601 with a lower surface roughness.

[0189] Example 1

[0190] A method for processing fracture grooves in ultra-slender stainless steel tubes, such as... Figure 1 As shown, it includes the following steps:

[0191] Step 1: Use the machine tool to adjust the position of the tool electrode 1 so that the plane where the discharge end 101 of the tool electrode 1 is located is perpendicular to the worktable surface 9 of the machine tool;

[0192] Specifically, the machine tool's worktable 9 is a horizontal plane, and the tool electrode 1 is vertically mounted on the machine tool and connected to the transmission rod mounted on the machine tool.

[0193] Step 2: Clamp the stainless steel pipe 6 using the bearing assembly and align the stainless steel pipe 6.

[0194] Specifically, first, fix two equal-height positioning blocks 3 and two auxiliary support blocks 4 on the worktable 9, use a dial indicator to align their sides parallel to the X-axis of the machine tool, and use the machine tool to adjust the position of the equal-height positioning blocks 3 and auxiliary support blocks 4, wherein the parallelism error is ≤0.01mm.

[0195] Then place the stainless steel tube 6 on the leveling block 3. Before placing it, pass the stainless steel tube 6 through the inner circle of the lower end of the tool electrode 1. Use the leveling block 3 to ensure that the stainless steel tube 6 is in a horizontal position. The distance between the two leveling blocks 3 is 30mm.

[0196] Next, place both ends of the stainless steel pipe 6 on the auxiliary support block 4, and finally fix it with the clamping plate 5.

[0197] Step 3: Use the machine tool to adjust the center line of the discharge end 101 of the tool electrode 1 to coincide with the central axis of the inner cavity of the stainless steel tube 6;

[0198] Specifically, the position of the stainless steel tube 6 is first adjusted by moving the bearing component upward along the X-axis of the machine tool so that the position of the stainless steel tube 6 to be processed is located within the discharge end 101 of the tool electrode 1.

[0199] Next, the S is measured using the machine tool's automatic centering module. 11 S 12 S 13 S 14 If the four values ​​are equal or the error is within ±0.02mm, then the center of the discharge end 101 of the tool electrode 1 is aligned with the central axis of the inner cavity of the stainless steel tube 6. If they are not aligned, the position of the bearing component is adjusted by the machine tool until the requirements are met.

[0200] Step 4: Using kerosene and water as the working fluid, perform electrical discharge machining on the stainless steel tube 6 using tool electrode 1 in the working fluid.

[0201] S101: Control the discharge end 101 of the tool electrode 1 to move eccentrically around the central axis of the inner cavity of the stainless steel tube 6.

[0202] Specifically, the machine tool drives the transmission rod 2 to swing within the swing plane YZ, thereby controlling the discharge end 101 of the tool electrode 1 to perform eccentric motion around the central axis of the inner cavity of the stainless steel tube 6 via the transmission rod 2; the direction of eccentric motion 8 is as follows: Figure 9 As shown.

[0203] The swing speed of transmission rod 2 is 0.5 rpm;

[0204] S 11 S 12 S 13 S 14 The actual measured values ​​were 2.055mm, 2.060mm, 2.065mm, and 2.050mm, respectively. At this time, S1 = 2.058mm.

[0205] The machining clearance S2 is 10 μm;

[0206] Single-sided feed rate O1O2=S1+(H1-H2)-S2=2.058+(0.5-0.3)-0.01=2.248mm;

[0207] The processing speed is 0.04 g / min.

[0208] S102: When the tool electrode 1 is in eccentric motion, energize the tool electrode 1 to perform electrical discharge machining.

[0209] Specifically, the electrical parameters meet the following requirements:

[0210] Pulse width 40μs, pulse interval 26μs, average machining current 1A, average machining voltage 40V.

[0211] Example 2

[0212] A processing device for fracture grooves on ultra-thin stainless steel tubes includes a tool electrode 1, a bearing assembly, and a drive assembly mounted on a machine tool. The bearing assembly is used to clamp the stainless steel tube 6, and the drive assembly is used to drive the tool electrode 1 to move eccentrically around the central axis of the inner cavity of the stainless steel tube 6, so as to realize the electrical discharge machining of the fracture groove 601 on the stainless steel tube, thereby solving the problem that it is difficult to process fracture grooves on ultra-thin stainless steel tubes.

[0213] Specifically, one end of the tool electrode 1 is annular, and the inner end of the annular ring has the same shape as the break groove 601. The other end of the tool electrode 1 is a conductive end 104, which is electrically connected to an output end of a power supply device installed on the machine tool to introduce current and transmit the current to the inner end. At this time, the inner end is a discharge end 101, which is sleeved on the outer end face of the stainless steel tube 6. During processing, the stainless steel tube 6 is electrically connected to the other output end of the power supply device, and the discharge end 101 of the tool electrode 1 moves eccentrically around the central axis of the inner cavity of the stainless steel tube 6. At this time, the discharge end 101 includes a working end 102 and a non-working end 103, so that the metal on the surface of the stainless steel tube 6 can be removed by discharging the working end 102 during processing.

[0214] During the eccentric movement of the tool electrode 1, the distance between the end face of the discharge end 101 and the end face to be processed of the stainless steel tube 6 continuously changes. A distance of 10-50 μm indicates the working state, i.e., the working end 102, while a distance greater than 50 μm indicates the non-working state, i.e., the non-working end 103. The processing trajectories of all working ends 102 together constitute the ultra-slender stainless steel tube breakage groove 601.

[0215] The center of the inner circle of the discharge end 101 of the tool electrode 1 coincides with the central axis of the inner cavity of the stainless steel tube 6, and there is a clearance between the discharge end 101 and the outer end face of the stainless steel tube 6. The diameter of the end face of the discharge end 101 is 20mm, which is 10 times the outer diameter of the stainless steel tube 6, so as to facilitate the determination of the value of the single-sided feed amount O1O2. During processing, the tool electrode 1 is driven to swing by the drive assembly. At this time, the discharge end 101 of the tool electrode 1 is in an eccentric motion state around the central axis of the inner cavity of the stainless steel tube 6.

[0216] Among them, the automatic centering module on the machine tool is used to measure S. 11 S 12 S 13 S 14 The corresponding values ​​are 2.055mm, 2.060mm, 2.065mm, and 2.050mm, respectively. At this time, S1 = 2.058mm.

[0217] Where S2 = 10 μm; H1 = 0.5 mm, H2 = 0.3 mm, S1 = 2.058 mm, and O1O2 = 2.248 mm.

[0218] When the center of the discharge end 101 of the adjustment tool electrode 1 coincides with the central axis of the inner cavity of the stainless steel tube 6, the tool electrode 1 is in an eccentric motion state under the action of the drive assembly.

[0219] The conductive end 104 of the tool electrode 1 is electrically connected to one output end of the power supply device installed on the machine tool, and the stainless steel tube 6 is electrically connected to the other output end of the power supply device. The power supply device includes a pulse power supply, and its two output ends are respectively connected to the positive and negative terminals of the pulse power supply to output pulse voltage.

[0220] During the processing, the electrical parameters must meet the following requirements:

[0221] Pulse width 40μs, pulse interval 26μs, average machining current 1A, average machining voltage 40V.

[0222] Specifically, the aforementioned drive assembly includes a transmission rod 2, one end of which is connected to the tool electrode 1, and the other end of which is mounted on a machine tool. The machine tool can control the transmission rod 2 to swing, thereby causing the discharge end 101 of the tool electrode 1 to move eccentrically around the central axis of the inner cavity of the stainless steel tube 6. During processing, the stainless steel tube 6 remains stationary.

[0223] During the processing, the non-electrical parameters satisfy the following:

[0224] The swing speed of transmission rod 2 is 0.5 rpm, the machining gap S2 is 10 μm, the machining speed is 0.04 g / min, and the single-sided feed amount O1O2 is 2.248 mm.

[0225] Specifically, the load-bearing components include a height positioning block 3 and an auxiliary support block 4 installed on the machine tool to place the stainless steel pipe 6 on the height positioning block 3 and the auxiliary support block 4 to clamp the stainless steel pipe 6.

[0226] The system includes two equal-height positioning blocks 3, which are located on both sides of the stainless steel pipe 6 to be processed, with a distance of 30mm between them.

[0227] The system includes two auxiliary support blocks 4 and two equal-height positioning blocks 3 located between the two auxiliary support blocks 4, so as to support and position the two ends of the stainless steel pipe 6 through the two auxiliary support blocks 4.

[0228] The upper surfaces of the level positioning block 3 and the auxiliary bearing block 4 are flush, and a V-shaped groove is provided on the upper surfaces of the level positioning block 3 and the auxiliary bearing block 4. The stainless steel pipe 6 is placed in the V-shaped groove to limit the movement of the stainless steel pipe 6.

[0229] Furthermore, a clamping plate 5 is provided on the leveling positioning block 3. The clamping plate 5 covers the V-groove and is engaged with the leveling positioning block 3 to limit the movement of the stainless steel tube 6 and further improve the stability of the stainless steel tube 6. For example, the angle of the V-groove is 90° and the depth is 10mm.

[0230] Before placing the stainless steel tube 6 on the leveling block 3, the tool electrode 1 needs to be aligned first. Then, the stainless steel tube 6 is inserted into the discharge end 101 of the tool electrode 1. Finally, the leveling block 3, the auxiliary bearing block 4 and the clamping plate 5 are used to clamp the stainless steel tube 6, and the leveling block 3 and the auxiliary bearing block 4 are used to align the stainless steel tube 6.

[0231] One end of the transmission rod 2 is connected to the tool electrode 1 and is parallel to the center line of the discharge end 101 of the tool electrode 1. During the processing, the other end of the transmission rod 2 is mounted on the machine tool so that the machine tool drives the transmission rod 2 to swing, and then drives the tool electrode 1 to move, so as to realize that the discharge end 101 of the tool electrode 1 makes an eccentric movement around the central axis of the inner cavity of the stainless steel tube 6.

[0232] In this way, the discharge end 101 of the tool electrode 1 moves eccentrically around the central axis of the inner cavity of the stainless steel tube 6 for one revolution, which can complete the processing of the stainless steel tube break groove 601, achieving one-time processing and significantly improving processing efficiency.

[0233] The above processing method was used to process the fracture grooves of the ultra-slender stainless steel tubes #01-#10. The processing parameters are shown in Table 1 below.

[0234] Table 1 Processing Parameters

[0235]

[0236] Processing requirements: The wall thickness of the fracture groove is 0.3±0.05mm, and the bevel angle α is 90°.

[0237] The test results are shown in Table 2 below.

[0238] Table 2 Detection Results

[0239]

[0240] The electrode consumption ratio is E / W*100%, where E is the change in the diameter of the discharge end of the tool electrode, and W is the initial diameter of the inner end of the tool electrode.

[0241] As shown in Table 2, the average depth of the fracture grooves of the 10 stainless steel tubes processed by this invention is 0.2146 mm, the standard deviation is 0.01427, and the coefficient of variation is 0.07. The fracture groove angle is 90°. The average wall thickness of the fracture groove is 0.299 mm, the standard deviation is 0.006681, and the coefficient of variation is 0.02. It can be seen that the processing method of this invention can realize the processing of fracture grooves on ultra-thin stainless steel tubes, and the processed fracture grooves have high precision and stability, will not damage the ultra-thin stainless steel tubes, and have less wear on the tool electrode.

[0242] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0243] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. An electro-discharge machining method for a notching groove of an ultra-long stainless steel pipe, characterized by: The working state comprises a plurality of electric spark machining points arranged circumferentially around the stainless steel pipe by using a tool electrode, and the machining of the breaking groove on the surface to be machined is realized; Wherein, the same electric spark machining point is in working state or non-working state by changing the distance between the electric spark machining point and the surface to be machined; During machining, the plurality of electric spark machining points arranged circumferentially around the stainless steel pipe form a continuous circular ring, and the inner circle end of the circular ring matches the shape of the breaking groove; The discharge end of the tool electrode is sleeved on the stainless steel pipe, and during machining, the discharge end of the tool electrode moves eccentrically around the central axis of the inner cavity of the stainless steel pipe, and during machining, the eccentric movement of the tool electrode is controlled by the machine tool, and the stainless steel pipe remains stationary; The machining direction is the circumferential direction of the outer end surface of the stainless steel pipe, and the center line of the circumferential direction coincides with the central axis of the inner cavity of the stainless steel pipe; The discharge end of the tool electrode comprises a plurality of working ends arranged in a ring shape, and during machining, the plurality of working ends are in non-synchronous and non-continuous machining state when the discharge end moves eccentrically around the central axis of the inner cavity of the stainless steel pipe; and the machining tracks of the plurality of working ends jointly form the breaking groove of the stainless steel pipe.

2. The method of claim 1, wherein: The lower end of the tool electrode is a discharge end, and a plurality of electric spark machining points are arranged on the discharge end, and during machining, the plurality of electric spark machining points arranged circumferentially around the stainless steel pipe are continuously and uninterruptedly distributed circumferentially around the stainless steel pipe.

3. The method of claim 1, wherein: The inner circle diameter of the discharge end of the tool electrode is 5-10 times the outer diameter of the stainless steel pipe, and before machining, the position of the stainless steel pipe is adjusted so that the central axis of the inner cavity of the stainless steel pipe coincides with the center line of the inner circle of the discharge end.

4. The method of claim 1, wherein: Before machining, the position to be machined of the stainless steel pipe is clamped by using two equal-height positioning blocks, and the two ends of the stainless steel pipe are clamped by using two auxiliary bearing blocks; Wherein, the distance between the two equal-height positioning blocks is 20-50 mm; Wherein, the central axis of the inner cavity of the stainless steel pipe is adjusted to coincide with the center line of the inner circle of the discharge end by adjusting the positions of the equal-height positioning blocks and the auxiliary bearing blocks.

5. The method of claim 1, wherein: The eccentric movement of the tool electrode is driven by the driving assembly; Wherein, the non-electric parameters satisfy: The swing speed of the driving assembly is 0.4-0.6 rpm, the machining gap is 10-50 μm, and the machining speed is 0.02-0.045 g / min.

6. The method of claim 1, wherein: During the eccentric movement of the tool electrode, the single-side feed amount O1O2 satisfies: O1O2=S1+(H1-H2)-S2 Wherein, H1 is the wall thickness of the stainless steel pipe; H2 is the wall thickness of the breaking groove; S1 is the distance between the discharge end of the tool electrode and the outer end surface of the stainless steel pipe before machining; and S2 is the machining gap; Wherein, the distance S1 between the discharge end of the tool electrode and the outer end surface of the stainless steel pipe satisfies: wherein S 11 , S 12 , S 13 , S 14 are actual excess gap values between the outer end surface of the stainless steel pipe and four points selected on the circular ring-shaped discharge end of the tool electrode, the four points being uniformly distributed on the circular ring-shaped discharge end.

7. The method of claim 1, wherein, During machining, the electric parameters satisfy: The pulse width is 30-60 μs, the pulse interval is 20-30 μs, the average machining current is 0.8-2 A, and the average machining voltage is 30-60 V.

8. The method of claim 1, wherein: During machining, the center of the discharge end of the tool electrode deviates from the central axis of the inner cavity of the stainless steel pipe in a straight line direction in any direction, and when the deviation distance reaches O1O2, the discharge end of the tool electrode moves eccentrically again around the central axis of the inner cavity of the stainless steel pipe.

Images