Casing end face sealing groove electrode machining method and application

Abstract

The invention discloses a machining method and application of a sealing groove electrode on the end face of a cartridge receiver. According to the machining method, a thin graphite electrode with the thickness being 0.5 mm and the height being 10 mm is obtained through milling by means of rough machining, semi-finish machining and finish machining. Meanwhile, the cutting-in part width of the milling cutter is smaller than the radius of the milling cutter, the rotating speed, the feeding amount and the like of the milling cutter are strictly controlled, the rigidity of the graphite flake is reserved, vibration generated during milling is reduced, the product quality and the product percent of pass are improved, and the problems that the graphite flake is prone to breakage and wide in top and narrow in bottom in the machining process of the thin graphite electrode are solved.

Description

Technical Field

[0001] This invention relates to the field of thin graphite electrode processing technology, and more specifically, to a method and application for processing sealing groove electrodes on the end face of a casing.

[0002] Background technology.

[0003] The outer ring assembly of the power turbine is made of GH3536 steel and has a ring-shaped structure. It is divided into 10 segments from a single ring using wire EDM. Each segment requires a narrow groove, 0.5 mm wide, 10 mm deep, and approximately 50 mm long, to be machined on both ends. Common milling processes require milling cutters with a length-to-diameter ratio greater than 20 to reach into the sealing groove on the end face of the part. However, due to the small and long cutter, there is insufficient rigidity, which can cause tool deflection and chatter when cutting high-temperature alloys, making it impossible to guarantee the required dimensions of the narrow groove. Electrical discharge machining (EDM) can effectively avoid tool deflection, but the groove structure requires thin and long electrodes. Graphite has low hardness, low strength, poor toughness, and high brittleness, making it prone to chipping and breakage during milling.

[0004] CN107263744A discloses a method for machining ultrathin-walled graphite electrodes, which involves selecting suitable diamond-coated tools T1 / T21 for roughing, T6 for finishing, and T19 for corner clearing, and controlling the machining parameters. During roughing, the spindle speeds are: T1 15000 rpm, T21 18000 rpm; feed rates are: T1 10000 mm / min, T21... 3500 mm / min; feed rate: T1 radial 4.2 mm / r, axial 1.5 mm / r, T21 radial 1.95 mm / r, axial 0.6 mm / r; machining time 15 min; during finishing, the spindle speed is 18000 rpm, feed rate is 4000 mm / min, feed amount is radial 1.0 mm / r, axial 0.18 mm / r, and machining time is 27 min. This patent, by controlling spindle speed, feed rate, feed amount, and machining time, produces ultra-thin-walled graphite electrodes with a thickness as low as 0.04–0.10 mm. The resulting graphite electrodes have a smooth appearance and do not chip. This patent can reduce chipping problems to some extent, but there is still a relatively high probability of chipping during machining, especially at the edges and corners of the graphite. Furthermore, there is some vibration during cutting, with obvious surface grooves, and when using the upper end of the tool, a phenomenon of being narrower at the top and wider at the bottom is easily observed. Summary of the Invention

[0005] The main technical problem this invention aims to solve is the high probability of chipping at the corners and edges in the preparation of ultrathin graphite electrodes using existing technologies, as well as defects such as surface ripples and a narrow top and wide bottom. This invention provides a method for machining sealing groove electrodes on the end face of a casing. The thin graphite electrodes prepared using this method are applied to the groove machining of power turbine components.

[0006] The objective of this invention is achieved through the following technical solution: A method for machining a sealing groove electrode on the end face of a casing, wherein the thin graphite electrode has a thickness of 0.5 mm and a height of 10 mm, and the steps include: S1. Rough machining; A clockwise rotating milling cutter cuts along the outer edge of a cuboid graphite matrix towards the center in a clockwise direction. The width of the milling cutter entering the workpiece is less than the radius of the milling cutter. The rotation speed is controlled at 8000~12000 r / min, the feed rate is 2800~3200 mm / min, and the allowance on each side is not less than 1.25 mm, to obtain a rough-machined graphite sheet. S2. Semi-finished product; Using a milling cutter II, the allowance is cut in a clockwise downward spiral motion to obtain an upper graphite sheet with a height of 3mm and a single-sided allowance of not less than 0.1mm, and a middle graphite sheet with a height of 3mm and a single-sided allowance of 0.2~0.3mm. The cutting parameters are a speed of 14000~16000r / min and a feed rate of 2400~2600mm / min to obtain a semi-finished graphite sheet. S3. Finishing; Using a milling cutter, milling is performed clockwise from the top in a spiral motion downwards at a speed of 18000~22000 r / min and a feed rate of 1400~1600 mm / min to obtain a thin graphite electrode.

[0007] Furthermore, the cuboid graphite substrate has dimensions of 210x50x40mm, and at least one thin graphite electrode is milled onto the cuboid graphite substrate. Specifically, five thin graphite electrodes are uniformly milled onto the cuboid graphite substrate.

[0008] Furthermore, the milling cutter is a diamond-coated milling cutter with a diameter of 10mm and a tip radius of 1mm. The helix angle of the milling cutter is 25°, which can reduce milling resistance and increase the chip groove space. When using this milling cutter for high-speed milling, it will not cause chipping due to poor chip removal, thus preventing chipping at the edges and corners of the blank.

[0009] Furthermore, the milling cutter adopts a layered machining method, with a layered machining depth of 1mm.

[0010] Furthermore, the first milling cutter has a rotational speed of 10000 r / min and a feed rate of 3000 mm / min, the second milling cutter has a rotational speed of 15000 r / min and a feed rate of 2500 mm / min, and the third milling cutter has a rotational speed of 20000 r / min and a feed rate of 1500 mm / min.

[0011] Furthermore, the second milling cutter is a diamond-coated milling cutter with a diameter of 6mm.

[0012] Furthermore, the milling cutter has a clockwise helical milling depth of 0.5 mm.

[0013] Furthermore, the semi-finished graphite sheet has a three-layer stepped structure from bottom to top, including an upper graphite sheet with a single-sided allowance of 0.1mm, a middle graphite sheet with a single-sided allowance of 0.25mm, and a lower graphite sheet with a single-sided allowance of 1.25mm. This stepped structure can ensure that the top processing electrode has sufficient rigid support and will not cause tool deflection or vibration.

[0014] Furthermore, the milling cutter three is a diamond-coated milling cutter with a diameter of 3mm and a tip radius of 1.5mm, which can effectively reduce milling force compared to a φ10 roughing milling cutter and avoid chipping at the sharp corners of the graphite sheet.

[0015] Furthermore, the depth of the triple helix of the milling cutter is 0.3 mm.

[0016] The thin graphite electrode prepared according to the above method is used for the groove machining of power turbine components.

[0017] Compared with existing technologies, the beneficial effects are: This invention uses roughing, semi-finishing, and finishing methods to mill a thin graphite electrode with a thickness of 0.5 mm and a height of 10 mm. During the machining process, a clockwise rotating milling cutter is used to machine from the outer edge towards the center in a clockwise climb milling manner. The clockwise rotation of the milling cutter ensures that the cutting force at the cutter tip always points inward towards the graphite matrix, milling the chips from the outside in. The milling force is inward, and combined with milling away the outer edge of the graphite matrix first, while retaining some material in the center, this prevents the material at the edges from becoming too thin and losing rigidity, thus effectively preventing chipping at the electrode edges. Furthermore, the width of the milling cutter entering the workpiece is smaller than the cutter radius, and when the cutter exits, the remaining material has a large contact surface with the workpiece body, providing a certain degree of rigidity and preventing chipping.

[0018] This invention also constructs a stepped semi-finishing structure. The semi-finishing allowance ensures sufficient rigid support for the top machining electrode, preventing tool deflection and chatter. During finishing, a clockwise spiral machining motion is used around the electrode from top to bottom, ensuring the milling force always points from the outside towards the inside of the graphite material, avoiding edge chipping. Combined with a layered milling method, spiraling downwards from the top of the graphite, a smaller depth of cut effectively prevents the tool from becoming narrower at the top and wider at the bottom.

[0019] This invention improves the quality and yield of thin graphite electrode products and solves the problem of chipping during graphite processing by strictly controlling the rotation mode and feed direction of the milling cutter during roughing, semi-finishing, and finishing, as well as the matching of milling cutter types and the control of parameters such as rotation speed, feed rate, and feed depth. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of roughing, semi-finishing, and finishing in Example 1.

[0021] Figure 2 This is a schematic diagram of the milling cutter rotation and feed in Example 1.

[0022] Figure 3 This is a schematic diagram of milling with a milling cutter in Example 1.

[0023] Figure 4 This is a diagram of the thin graphite electrode obtained in Example 1; Figure 5 This is a schematic diagram of the reciprocating milling process in Example 2.

[0024] Figure 6 This is a schematic diagram of graphite chipping in Example 2.

[0025] Figure 7 This is a schematic diagram of the milling cutter rotation and feed in Example 3.

[0026] Figure 8 This is a schematic diagram of milling with a milling cutter in Example 4; Figure 9 This is a schematic diagram of the milling cutter deflection phenomenon in Example 5. Detailed Implementation

[0027] The following examples further explain and clarify the invention, but the specific examples do not limit the invention in any way.

[0028] Example 1 This embodiment provides a method for machining the sealing groove electrode on the end face of a casing, the steps of which include: S1. Positioning and installation; Mount the graphite fixture on a high-speed five-axis CNC machine tool. Set the fixture's positioning center to G54XY zero point and the angular direction of the fixture to the positive X-axis. Then, mount the 210x50x40mm graphite substrate on the fixture's positioning circle and clamp it securely. The runout of the outer diameter of the part should be within 0.01mm at the G54 center. Set the upper surface of the part to G54 Z zero point.

[0029] S2. Perform rough machining; A diamond-coated end mill with a φ10XR1 helix angle of 25° is used to rotate clockwise and feed clockwise along the outer edge of the part. The width of the end mill entering the part is controlled to be less than the end mill radius. The process is carried out in layers with a depth of 1 mm per layer. The cutting parameters are a speed of 10000 r / min, a feed rate of 3000 mm / min, and a time of 75 min. The result is a single-sided allowance of not less than 1.25 mm, which yields a rough-machined graphite sheet.

[0030] S3, Semi-finished; A φ6 diameter diamond-coated end mill was used. The end mill rotated clockwise and machined in a clockwise spiral layer from top to bottom, controlling the depth of each layer to be 0.5 mm. The cutting parameters were a speed of 15000 r / min and a feed rate of 2500 mm / min. This process yielded a three-layer stepped semi-finished graphite sheet, including an upper graphite sheet with a single-sided allowance of 0.1 mm and a height of 3 mm, a middle graphite sheet with a single-sided allowance of 0.25 mm and a height of 3 mm, and a lower graphite sheet with a single-sided allowance of 1.25 mm and a height of 4 mm. S4, finishing; A diamond-coated milling cutter with a diameter of φ3R1.5 was used. The milling cutter rotated clockwise and was used to machine from top to bottom in a clockwise spiral motion. The depth of each layer was controlled to be 0.3 mm. The cutting parameters were a speed of 20000 r / min, a feed rate of 1500 mm / min, and a time of 60 min, to obtain a thin graphite electrode with a thickness of 0.5 mm and a height of 10 mm.

[0031] Testing revealed that the thin graphite electrode prepared in this embodiment exhibited no chipping at its edges and corners, resulting in a higher pass rate. The surface roughness of the graphite electrode reached 0.8, and the width of the graphite electrode was uniform throughout.

[0032] Example 2 This embodiment provides a method for machining the sealing groove electrode on the end face of the casing. During rough machining, a reciprocating milling process in an "arch" shape is used. Figure 5 As shown, the cutting tool enters from one side of the edge and then returns from the other side. When the tool begins to cut from the outside in, the allowance on the other side of the graphite matrix is ​​very thick. The thick chips have good rigidity and will not chip. When the tool is about to exit from the inside to the other side, as... Figure 6 As shown, the material at the edge becomes thinner and thinner, and the rigidity becomes worse. As the milling force continues to move outward, the edge becomes thinner and thinner, making it prone to chipping.

[0033] Example 3 This embodiment provides a method for machining the sealing groove electrode on the end face of the casing, such as... Figure 7 As shown, during roughing, the milling cutter rotates clockwise and feeds counterclockwise along the outer edge of the graphite substrate. Because the milling cutter processes counterclockwise along the outer edge of the part, and the tool rotates clockwise, the tool tip always mills the chips from the inside out. The milling force is outward, which easily leads to outward chipping.

[0034] Example 4 This embodiment provides a method for machining the sealing groove electrode on the end face of a casing. During rough machining, the milling cutter rotates clockwise and feeds clockwise along the outer edge of the graphite substrate. Figure 8As shown, the width of the end mill cutter into the workpiece is greater than the end mill radius. When the end mill exits, the remaining material has a small contact area with the graphite body, almost like a thin sheet, lacking rigidity and prone to chipping.

[0035] Example 5 This embodiment provides a method for machining the sealing groove electrode on the end face of the casing. During finishing, when milling the right side of the electrode, the top of the electrode deflects to the left, and when milling the left side of the electrode, the top of the electrode deflects to the right. Because there is a deflection phenomenon on both sides of the top of the electrode, the thin graphite electrode exhibits a phenomenon of being wider at the top and narrower at the bottom.

[0036] Example 6 This embodiment provides a method for machining the sealing groove electrode on the end face of a casing, the steps of which include: S1. Positioning and installation; Mount the graphite fixture on a high-speed five-axis CNC machine tool. Set the fixture's positioning center to G54XY zero point and the angular direction of the fixture to the positive X-axis. Then, mount the 210x50x40mm graphite substrate on the fixture's positioning circle and clamp it securely. The runout of the outer diameter of the part should be within 0.01mm at the G54 center. Set the upper surface of the part to G54 Z zero point.

[0037] S2. Perform rough machining; A diamond-coated end mill with a φ10XR1 helix angle of 25° is rotated clockwise and fed clockwise along the outer edge of the part. The width of the end mill entering the part is controlled to be less than the end mill radius. The process is carried out in layers with a depth of 1 mm per layer. The cutting parameters are a rotation speed of 8000 r / min and a feed rate of 2800 mm / min. The allowance on each side is not less than 1.25 mm, resulting in a rough-machined graphite sheet.

[0038] S3, Semi-finished; A φ6 diameter diamond-coated milling cutter was used. The cutter rotated clockwise and machined layer by layer from top to bottom in a clockwise spiral direction, controlling the depth of each layer to be 0.5 mm. The cutting parameters were a speed of 14000 r / min and a feed of 2400 mm / min. This process produced a three-layer stepped semi-finished graphite sheet, including an upper graphite sheet with a single-sided allowance of 0.1 mm and a height of 3 mm, a middle graphite sheet with a single-sided allowance of 0.25 mm and a height of 3 mm, and a lower graphite sheet with a single-sided allowance of 1.25 mm and a height of 4 mm.

[0039] S4, finishing; A diamond-coated milling cutter with a diameter of φ3R1.5 was used. The milling cutter rotated clockwise and was used to process the material from top to bottom in a clockwise spiral motion. The depth of each layer was controlled to be 0.3 mm. The cutting parameters were a rotation speed of S18000 r / min and a feed rate of 1400 mm / min, resulting in a thin graphite electrode with a thickness of 0.5 mm and a height of 10 mm.

[0040] Example 7 This embodiment provides a method for machining the sealing groove electrode on the end face of a casing, the steps of which include: S1. Positioning and installation; Mount the graphite fixture on a high-speed five-axis CNC machine tool. Set the fixture's positioning center to G54XY zero point and the angular direction of the fixture to the positive X-axis. Then, mount the 210x50x40mm graphite substrate on the fixture's positioning circle and clamp it securely. The runout of the outer diameter of the part should be within 0.01mm at the G54 center. Set the upper surface of the part to G54 Z zero point.

[0041] S2. Perform rough machining; A diamond-coated end mill with a φ10XR1 helix angle of 25° is used to rotate clockwise and feed clockwise along the outer edge of the part. The width of the end mill entering the part is controlled to be less than the radius of the end mill. The process is carried out in layers with a depth of 1 mm per layer. The cutting parameters are a rotation speed of 12000 r / min and a feed rate of 3200 mm / min. The allowance on each side is not less than 1.25 mm, resulting in a rough-machined graphite sheet.

[0042] S3, Semi-finished; A φ6 diameter diamond-coated milling cutter was used. The cutter rotated clockwise and machined layer by layer from top to bottom in a clockwise spiral direction, controlling the depth of each layer to be 0.5 mm. The cutting parameters were a speed of 16000 r / min and a feed of 2600 mm / min. This process produced a three-layer stepped semi-finished graphite sheet, including an upper graphite sheet with a single-sided allowance of 0.1 mm and a height of 3 mm, a middle graphite sheet with a single-sided allowance of 0.25 mm and a height of 3 mm, and a lower graphite sheet with a single-sided allowance of 1.25 mm and a height of 4 mm.

[0043] S4, finishing; A diamond-coated milling cutter with a diameter of φ3R1.5 was used. The milling cutter rotated clockwise and was used to process the material from top to bottom in a clockwise spiral motion. The depth of each layer was controlled to be 0.3 mm. The cutting parameters were a rotation speed of S22000 r / min and a feed rate of 1600 mm / min, resulting in a thin graphite electrode with a thickness of 0.5 mm and a height of 10 mm.

[0044] Example 8 This embodiment provides a method for machining the sealing groove electrode on the end face of a casing, the steps of which include: S1. Positioning and installation; Mount the graphite fixture on a high-speed five-axis CNC machine tool. Set the fixture's positioning center to G54XY zero point and the angular direction of the fixture to the positive X-axis. Then, mount the 210x50x40mm graphite substrate on the fixture's positioning circle and clamp it securely. The runout of the outer diameter of the part should be within 0.01mm at the G54 center. Set the upper surface of the part to G54 Z zero point.

[0045] S2. Perform rough machining; A diamond-coated end mill with a φ10XR1 diameter and a helix angle of 25° is used to rotate clockwise and feed clockwise along the outer edge of the part. The width of the end mill entering the part is controlled to be less than the end mill radius. A layered machining method is used, with each layer having a depth of 1 mm. The cutting parameters are a rotation speed of 12000 r / min, a feed rate of 3200 mm / min, and a machining time of 75 min. This yields a single-sided allowance of not less than 1.25 mm, resulting in a rough-machined graphite sheet.

[0046] S3, Semi-finished; A φ6 diameter diamond-coated milling cutter was used. The cutter rotated clockwise and machined layer by layer from top to bottom in a clockwise spiral direction, controlling the depth of each layer to be 0.5 mm. The cutting parameters were a speed of 14000 r / min and a feed of 2400 mm / min. This process produced a three-layer stepped semi-finished graphite sheet, including an upper graphite sheet with a single-sided allowance of 0.1 mm and a height of 3 mm, a middle graphite sheet with a single-sided allowance of 0.25 mm and a height of 3 mm, and a lower graphite sheet with a single-sided allowance of 1.25 mm and a height of 4 mm.

[0047] S4, finishing; A diamond-coated milling cutter with a diameter of φ3R1.5 was used. The milling cutter rotated clockwise and was used to machine from top to bottom in a clockwise spiral motion. The depth of each layer was controlled to be 0.3 mm. The cutting parameters were a speed of 20000 r / min, a feed rate of 1500 mm / min, and a time of 75 min, resulting in a thin graphite electrode with a thickness of 0.5 mm and a height of 10 mm.

[0048] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for machining a sealing groove electrode on the end face of a casing, characterized in that, The thin graphite electrode has a thickness of 0.5 mm and a height of 10 mm. The steps include: S1. Rough machining; A clockwise rotating milling cutter cuts along the outer edge of a cuboid graphite matrix towards the center in a clockwise direction. The width of the milling cutter entering the workpiece is less than the radius of the milling cutter. The rotation speed is controlled at 8000~12000 r / min, the feed rate is 2800~3200 mm / min, and the allowance on each side is not less than 1.25 mm, to obtain a rough-machined graphite sheet. S2. Semi-finished product; First, use milling cutter 2 to cut the allowance in a clockwise spiral motion to obtain an upper graphite sheet with a height of 3mm and a single-sided allowance of not less than 0.1mm. Then, adjust the milling cutter's cutting allowance to obtain a middle graphite sheet with a height of 3mm and a single-sided allowance of 0.2~0.3mm. The cutting parameters are a speed of 14000~16000r / min and a feed rate of 2400~2600mm / min to obtain a semi-finished graphite sheet. S3. Finishing; Using a milling cutter, milling is performed clockwise from the top in a spiral motion downwards at a speed of 18000~22000 r / min and a feed rate of 1400~1600 mm / min to obtain a thin graphite electrode.

2. The method for machining the sealing groove electrode on the end face of the casing according to claim 1, characterized in that, The rectangular graphite substrate has dimensions of 210x50x40mm, and at least one thin graphite electrode is milled on the rectangular graphite substrate.

3. The method for machining the sealing groove electrode on the end face of the casing according to claim 1, characterized in that, The milling cutter is a diamond-coated milling cutter with a diameter of 10 mm and a tip radius of 1 mm, and the helix angle of the milling cutter is 25°.

4. The method for machining the sealing groove electrode on the end face of the casing according to claim 1, characterized in that, The milling cutter adopts a layered machining method, with a layered machining depth of 1mm.

5. The method for machining the sealing groove electrode on the end face of the casing according to claim 1, characterized in that, The second milling cutter is a diamond-coated milling cutter with a diameter of 6mm.

6. The method for machining the sealing groove electrode on the end face of the casing according to claim 1, characterized in that, The depth of the clockwise helix of the milling cutter is 0.5 mm.

7. The method for machining the sealing groove electrode on the end face of the casing according to claim 1, characterized in that, The semi-finished graphite sheet has a three-layer stepped structure from bottom to top, including an upper graphite sheet with a single-sided allowance of 0.1 mm, a middle graphite sheet with a single-sided allowance of 0.25 mm, and a lower graphite sheet with a single-sided allowance of 1.25 mm.

8. The method for machining the sealing groove electrode on the end face of the casing according to claim 1, characterized in that, The second milling cutter is a diamond-coated milling cutter with a diameter of 3mm and a tip radius of 1.5mm.

9. The method for machining the sealing groove electrode on the end face of the casing according to claim 1, characterized in that, The depth of the triple helix of the milling cutter is 0.3 mm.

10. The thin graphite electrode prepared by any one of claims 1 to 9 is used in the groove machining of a power turbine assembly.

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