Multi-head super-large-lead spiral groove machining method

Abstract

The invention relates to the technical field of multi-head ultra-large-lead spiral groove machining, and discloses a multi-head ultra-large-lead spiral groove machining method which comprises the steps that a blank is hoisted to a rotation center of a workbench and is vertically placed, and the axis of the blank is adjusted to coincide with the rotation center of the workbench; a boring machine with a rotary table is used for machining, a blank is clamped to the rotary center of the rotary table, and linkage machining of a spiral groove is achieved through rotation of the rotary table and Y-axis movement (the rotary center of the rotary table is rotated to enable the blank to rotate); on the premise of guaranteeing the machining quality, compared with left and right cutter machining of each layer, half of the machining time can be shortened, the machining efficiency is improved, the cutter has no idle stroke, the machining efficiency is improved, meanwhile, errors caused by machine tool precision can be reduced through trial cutting angle calculation compensation, and the machining precision is improved. And the problem that the old machine tool exceeds the machining precision limit and cannot machine is solved.

Description

Technical Field

[0001] This invention relates to the field of multi-head ultra-large lead spiral groove machining technology, and particularly to a method for machining multi-head ultra-large lead spiral grooves. Background Technology

[0002] The machining of multi-start spiral grooves in water jackets is generally limited by the objective condition of excessively large lead dimensions, and can only be performed using mill-turn machining centers and lathes. Mill-turn machining centers horizontally mount the workpiece between the chuck and tailstock, utilizing the CNC linkage between the chuck indexing and the milling head to machine the spiral grooves. This method is more suitable for small to medium-sized, non-thin-walled workpieces. However, due to limitations in machine tool travel, load-bearing capacity, and clamping capacity, it is difficult to achieve this for machining ultra-large and ultra-heavy parts. When using a lathe, for parts with large leads, the lathe's Z-axis feed cannot be matched with the rotational speed, making machining impossible.

[0003] Using a gantry milling machine for angled machining requires three to four adjustments to process different areas, resulting in inconsistencies in tool spacing between areas, tool transition steps, and extremely poor machining accuracy. Furthermore, with gantry milling, the tool axis cannot maintain a constant radial direction, leaving large residual tool fillets at the root of the helical groove that cannot be removed, failing to meet the actual requirements. Moreover, multiple interpolation operations using this method require extremely long tool lengths for larger diameters (Φ3440), generating significant vibrations during machining, compromising machining accuracy and surface finish, and resulting in low machining efficiency.

[0004] Therefore, the above problems are solved by a multi-head ultra-large lead spiral groove machining method. Summary of the Invention

[0005] The purpose of this invention is to provide a method for machining multi-head ultra-large lead spiral grooves to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: the billet is hoisted onto the rotation center of the worktable, the billet is placed upright, and the axis of the billet is adjusted to coincide with the rotation center of the worktable; The workpiece is clamped to the rotation center of the rotary platform and the spiral groove is machined by rotating the workpiece and moving the Y-axis (rotating the rotation center of the workpiece causes the workpiece to rotate). A single-headed spiral shallow groove was test-cut on the outer circle of the blank, with one cut from top to bottom and another from bottom to top, with a depth of 0.5-1mm. After machining, the actual value of the spiral groove width was measured and compared with the theoretical value to obtain the deviation value ΔL1. The deviation value ΔL1 was then calculated according to the formula... The compensation angle θ is calculated, where θ1 is the helix angle, L2 is the lead, and ΔL1 is the slot width deviation value. The compensation angle θ is added to the machining program before the reverse rotation command of the worktable using the rotation coordinate system transformation command of the CNC system. The entire machining program for the spiral groove is divided into program segments according to the rotation of the rotary table every 90°, and executed sequentially. The multi-start spiral groove is milled by CNC linkage between the rotation of the table (B-axis) and the longitudinal movement of the boring machine milling head (Y-axis). The multi-head spiral groove is processed by a combination of interval processing and layered cutting. First, a groove is processed with two grooves in between. Each groove is cut multiple times to the final depth of 35mm, with each cut depth being 5mm. This process is repeated until all spiral grooves are processed to the target size.

[0007] Preferably, the multi-head spiral groove is a 12-head spiral groove, and the groove skipping process is carried out by skipping two groove positions.

[0008] Preferably, the billet is divided into three parts, including a fixing ring, a relief groove, and a spiral groove. The fixing ring is located at both ends of the billet, two relief grooves are formed between the two fixing rings, and a spiral groove is formed between the two relief grooves.

[0009] Preferably, the spiral groove method is divided into two types. One cutting method is: the tool diameter is greater than half the groove width, and the layered alternating cutting method is adopted. When cutting each layer, the tool first cuts on one side of the groove, and then moves to the other side to cut, and the tool paths on both sides have an overlapping area in the groove width direction.

[0010] Preferably, the width of the overlapping area is: 2 × tool diameter - groove width.

[0011] Preferably, another chip-cutting method is as follows: when the diameter of the milling cutter is equal to the width of the spiral groove, a single spiral groove is machined by a unidirectional continuous cutting method. The rotary table rotates continuously in one direction, and the Y-axis moves in coordination to complete the cutting of one layer of a single spiral groove in one go.

[0012] Preferably, the depth of a single spiral groove completed in one go is 5mm.

[0013] The technical effects and advantages of this invention are as follows: 1. Under the premise of ensuring processing quality, this invention can reduce the processing time by half compared to processing one cut on each side of each layer, thereby improving processing efficiency. Moreover, the tool has no idle stroke, which further improves processing efficiency.

[0014] 2. This invention can reduce errors caused by machine tool precision by calculating and compensating for the angle of trial cutting, and avoid the problem of not being able to process due to the machine tool being too old and exceeding the processing precision limit.

[0015] 3. In this invention, the machining program is divided into segments every 90 degrees. For example, if the total length of the spiral groove on the blank is 6210 mm and the spiral groove lead is 1680 mm, it is divided into 15 segments, as shown in the segmented program below. The advantage of using segmented CNC programming is that some ordinary CNC machine tools cannot recognize the zero-crossing point of the rotary table, causing errors in reverse rotation machining. Using segmented CNC programming can effectively solve the zero-crossing point problem and improve the high controllability and high precision of spiral groove machining.

[0016] 4. In this invention, the machine tool rotates forward in coordination with the Y-axis movement speed ratio, and the Y-axis completes single-groove machining from bottom to top. At this time, the Y-axis is at the upper part of the cylinder, rotating to another spiral groove. The machine tool then rotates backward in coordination with the Y-axis movement speed ratio, and the Y-axis completes single-groove machining from top to bottom. This machining method ensures that the cutting tool and groove width are the same, avoiding the need for two cuts to achieve the required groove width for each layer of the spiral groove, and preventing discrepancies between the groove width and the actual size caused by the backlash inherent in the machine tool's rotary table. Furthermore, each cut in the single spiral groove layer cutting is performed in one direction, preventing backlash from causing deviations in the groove width dimensions. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the billet being installed at the center of the worktable rotation.

[0018] Figure 2 This is a schematic diagram of blank cutting in accordance with the present invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] Example 1 This invention provides, for example Figures 1 to 2 The above describes a method for machining multi-head ultra-large lead spiral grooves, with reference to... Figure 1 The billet is hoisted onto the center of the workbench rotation, placed upright, and its axis is adjusted to coincide with the center of the workbench rotation.

[0021] First, the blank is vertically hoisted onto the rotary worktable. The blank is placed upright with four level shims underneath. Then, the center of the blank is adjusted to be consistent with the rotation center of the worktable using jacks. Four pressure points are evenly distributed around the circumference of the relief groove at the bottom of the spiral groove to ensure that the blank can be installed and fixed on the rotation center of the worktable, preventing the blank from shaking during processing. This ensures that the rotation center of the blank is consistent with the rotation axis of the machine tool, reducing processing errors and vibrations caused by eccentricity from the source, and laying a stable foundation for subsequent high-precision spiral groove processing.

[0022] The vertical clamping method, combined with jack fine-tuning, effectively utilizes the billet's own weight to enhance stability compared to horizontal clamping, reducing deformation of long billets caused by gravity sagging, making it particularly suitable for processing ultra-large billets.

[0023] The boring machine with a rotary table is used to process the helical groove. The workpiece is clamped to the center of the rotary platform. The helical groove is processed by rotating the workpiece and moving the Y-axis. Since the workpiece is located in the center of the workpiece, the tool extension length is relatively long. A universal milling head is added to extend the tool extension length, so as to ensure that the tool length is smaller, prevent greater vibration during processing, and ensure processing quality.

[0024] The CNC program is used to test cut two adjacent spiral grooves on the outer circle of the part. After machining, the groove width and pitch are measured. Based on the measurement results, the forward and reverse clearance angle of the computer tool rotary table is calculated as shown below. The value is then compensated to the value before the program reverses, reducing the machining tool deviation caused by the machine tool's rotational clearance.

[0025] In the formula: θ is the compensation angle; ∆L1 is the slot width or pitch deviation value; θ1 is the helix angle; L2 is the lead.

[0026] The compensation angle is added before the reverse rotation machining program by rotating the coordinate system (TRANS B=θ) to eliminate backlash. After adding the compensation, a test cut is performed, and measurements are taken to confirm that the compensation is correct.

[0027] In the machining program, each 90-degree rotation is divided into a segment. For example, if the total length of the spiral groove on the blank is 6210 mm and the spiral groove lead is 1680 mm, it is divided into 15 segments, as shown in the segmented program below. The advantage of using segmented CNC programming is that some ordinary CNC machine tools cannot recognize the zero-crossing point of the rotary table, causing errors in reverse rotation machining. Using segmented CNC programming can effectively solve the zero-crossing point problem and improve the high controllability and high precision of spiral groove machining.

[0028] By adopting a segmented machining strategy, the continuous and ultra-long spiral path is discretized into multiple short program segments of 90° intervals. This effectively avoids calculation errors or data overflow problems that may occur when the CNC system processes ultra-long programs, and enhances the stability and reliability of program operation. It is particularly suitable for machining spiral grooves with large leads and total lengths.

[0029] During the processing, the multi-head spiral grooves are processed by a combination of interval processing and layer cutting. First, a groove is processed with two grooves in between. Each groove is cut multiple times to the final depth of 35mm, with each cut depth being 5mm. This process is repeated until all spiral grooves are processed to the target size.

[0030] Intermittent processing can disperse processing heat and cutting force, avoiding thermal deformation and stress deformation caused by concentration on one side of the blank.

[0031] "Layered cutting" reduces the cutting force and heat of a single cut, lowers the tool load and the risk of workpiece deformation. The combination of these two methods significantly improves the shape accuracy and surface quality of deep groove machining while ensuring machining efficiency and protecting the tool.

[0032] During the machining process, a tool with a diameter greater than half the groove width is used, that is, a groove width of 45mm. A 32mm diameter tool is used for chip removal, which is combined with the interval machining method.

[0033] refer to Figure 1 Place the billet at the center of the worktable rotation, stand the billet upright, and place four equal-height shims underneath it. Then, use jacks to adjust the center of the billet to be consistent with the center of the worktable rotation, and then use clamps to fix the billet on the center of the worktable rotation.

[0034] The retaining ring and the tool relief groove form a stepped shape, and the clamping fixture holds the top of the retaining ring and the bottom of the tool relief groove.

[0035] The 32mm diameter cutter enters from the relief groove at the bottom of the blank and begins cutting. Because the groove width is 45mm, the diameter of the cutting cutter is only 32mm, and there is a 19mm overlap area between the cutters on the left and right sides in the middle.

[0036] During cutting, first cut along the left side of the spiral groove to a depth of 1mm. Using the uncut surface of the billet as the zero point, advance the tool 1mm, entering from the lower side of the billet through the retraction groove. Start cutting from bottom to top. When the spiral groove reaches the top, the worktable rotation center rotates slightly, causing the billet to rotate so that the 32mm diameter tool is located on the right side of the spiral groove. Move to the right side of the spiral groove, using the uncut surface of the billet as the zero point, and advance the tool 2mm, cutting from top to bottom along the right side of the spiral groove. At this time, there is a 19mm overlap area in the middle.

[0037] The first cut enters from the relief groove at the bottom of the billet, starting from the left side of the spiral groove and cutting from bottom to top, with a cutting depth of 1mm. Taking the uncut surface of the billet as the zero point, the cutter advances 1mm, at which point the spiral groove depth is 1mm and the groove width is 32mm.

[0038] The second cut begins from the retraction groove at the top of the billet. The worktable rotates slightly, causing the billet to rotate, positioning the 32mm diameter tool on the right side of the spiral groove. The tool cuts along the right side of the spiral groove from top to bottom, with a cutting depth of 2mm. Using the uncut surface of the billet as the zero point, the tool advances 2mm. At this point, the depth on the right side of the spiral groove is 2mm, the depth on the left side is 1mm, the groove width is 45mm, and the overlap area in the middle is 19mm.

[0039] The third cut enters from the retraction groove at the top of the billet. The worktable rotates slightly, causing the billet to rotate, so that the 32mm diameter tool is positioned on the left side of the spiral groove. Cutting begins from bottom to top along the left side of the spiral groove, with a cutting depth of 3mm. Taking the uncut surface of the billet as the zero point, the tool advances 3mm. At this point, the depth on the right side of the spiral groove is 2mm, the depth on the left side of the spiral groove is 3mm, the groove width is 45mm, and the overlap area in the middle is 19mm.

[0040] The fourth cut enters from the retraction groove at the top of the billet. The worktable rotates slightly, causing the billet to rotate, so that the 32mm diameter tool is located on the right side of the spiral groove. Cutting begins from top to bottom along the right side of the spiral groove, with a cutting depth of 4mm. Taking the uncut surface of the billet as the zero point, the tool advances 4mm. At this time, the depth of the right side of the spiral groove is 4mm, the depth of the left side of the spiral groove is 3mm, the groove width is 45mm, and the overlap area in the middle is 19mm.

[0041] The fifth cut enters from the retraction groove at the top of the billet. The worktable rotates slightly, causing the billet to rotate, so that the 32mm diameter tool is positioned on the left side of the spiral groove. Cutting begins from bottom to top along the left side of the spiral groove, with a cutting depth of 5mm. Taking the uncut surface of the billet as the zero point, the tool advances 5mm. At this point, the depth on the right side of the spiral groove is 4mm, the depth on the left side of the spiral groove is 5mm, the groove width is 45mm, and the overlap area in the middle is 19mm.

[0042] The sixth cut enters from the retraction groove at the top of the billet. The worktable rotates slightly, causing the billet to rotate, so that the 32mm diameter tool is located on the right side of the spiral groove. Cutting begins from top to bottom along the right side of the spiral groove, with a cutting depth of 5mm. Taking the uncut surface of the billet as the zero point, the tool advances 5mm. At this time, the depth of the right side of the spiral groove is 5mm, the depth of the left side of the spiral groove is 5mm, the groove width is 45mm, and the overlap area in the middle is 19mm.

[0043] At this point, the first stage of cutting for the first spiral groove has been completed, and the worktable rotation center rotates at an angle equal to the angle between two spiral grooves.

[0044] In other words, 12 spiral grooves are machined on the surface of the blank, divided into three groups of four. Taking the first spiral groove as the reference, the second and third spiral grooves are skipped before machining the fourth spiral groove.

[0045] For example: the first group consists of the first, fourth, seventh, and tenth spiral grooves.

[0046] The second group consists of: the second spiral groove, the fifth spiral groove, the eighth spiral groove, and the eleventh spiral groove.

[0047] The third group consists of: the third spiral groove, the sixth spiral groove, the ninth spiral groove, and the twelfth spiral groove.

[0048] After processing the first group, the processing program will process the second group, and then the third group.

[0049] For example, the first group will machine the first spiral groove to a depth of 5mm, then machine the fourth spiral groove, then the seventh spiral groove, and finally the tenth spiral groove. At this point, the depth of all four spiral grooves in the first group will be 5mm, which means that the first stage of machining the spiral grooves in the first group has been completed. The machining program will then rotate the center of the worktable to machine the second group.

[0050] After the second group of four threaded grooves are machined in sequence, and the depth of each of the four spiral grooves in the second group is 5mm, it means that the first stage of the second group of spiral grooves has been completed. The machining program will then rotate the center of the worktable to machine the third group.

[0051] After the four threaded grooves in the third group are machined in sequence, and the depth of each of the four spiral grooves in the third group is 5mm, it means that the first stage of machining the spiral grooves in the third group has been completed. The machining program will then rotate the center of the worktable to machine the first group again.

[0052] The second stage of processing begins, where each spiral groove is machined to a depth of 10mm.

[0053] This process continues in the same manner, with each processing depth being 5mm. That is, the first processing depth is 5mm, the second processing depth is 10mm, the third processing depth is 15mm, and so on, until the depth of the 12 spiral grooves reaches 35mm, at which point the entire blank is processed.

[0054] While ensuring processing quality, compared to processing each layer with one cut on each side, the processing time can be reduced by half, improving processing efficiency. Furthermore, the tool has no idle stroke, further enhancing processing efficiency.

[0055] In addition, by using an interval processing method, the next spiral groove is processed every two spiral grooves to prevent excessive deformation of the billet.

[0056] When used together, these two techniques avoid thermal and stress deformation caused by concentration on one side of the workpiece; "layered cutting" reduces the cutting force and heat of a single cut, lowering tool load and the risk of workpiece deformation. The combination of these two techniques significantly improves the shape accuracy and surface quality of deep groove machining while ensuring machining efficiency, and protects the cutting tool.

[0057] Before processing, perform a trial cut of one end of the spiral groove on both sides of the outer circle of the blank, with a depth of 1mm, according to the above processing method. After processing, measure the actual value of the spiral groove width and compare it with the theoretical value to obtain the deviation value ΔL1. Then, calculate the deviation value ΔL1 according to the formula... The compensation angle θ is calculated, where θ1 is the helix angle, L2 is the lead, and ΔL1 is the slot width deviation. The compensation angle is added before the program segment of the reverse rotation machining from top to bottom of the rotary table to compensate for the reverse rotation clearance, ensuring that the machine tool's forward and reverse rotation machining are consistent.

[0058] Example 2 Another cutting method is as follows: When the diameter of the milling cutter is equal to the width of the spiral groove, a single spiral groove is machined using a unidirectional continuous cutting method. The rotary table rotates continuously in one direction, and the Y-axis moves in coordination, completing the cutting of one layer of a single spiral groove in one go. The depth of a single spiral groove completed in one go is 5mm.

[0059] refer to Figure 1 Place the billet at the center of the worktable rotation, stand the billet upright, and place four equal-height shims underneath. Then, use jacks to adjust the center of the billet to be consistent with the center of the worktable rotation, and then use clamping fixtures to fix the billet on the center of the worktable rotation.

[0060] The retaining ring and the tool relief groove form a stepped shape, and the clamping fixture holds the top of the retaining ring and the bottom of the tool relief groove.

[0061] A 45mm diameter cutting tool enters from the relief groove at the bottom of the blank and begins chip removal.

[0062] During cutting, the chip depth is 1mm. Taking the uncut surface of the blank as the zero point, the infeed is 1mm. It enters from the lower side of the blank through the retraction groove and starts cutting from bottom to top. When the spiral groove chip reaches the top, it cuts from top to bottom. Taking the uncut surface of the blank as the zero point, the infeed is 2mm. It moves back and forth until the groove depth is 5mm, completing the preliminary machining.

[0063] For example, the first cut enters from the relief groove at the bottom of the billet and begins cutting from bottom to top. Taking the uncut surface of the billet as the zero point, the cut is 1mm deep. At this time, the depth of the spiral groove is 1mm and the groove width is 45mm.

[0064] The second cut begins from the retraction groove at the top of the billet, cutting from top to bottom. Taking the uncut surface of the billet as the zero point, the cut is 2mm deep. At this point, the depth of the spiral groove is 2mm and the groove width is 45mm.

[0065] The third cut enters from the retraction groove at the bottom of the billet and begins cutting from bottom to top. Taking the uncut surface of the billet as the zero point, the cut is 3mm deep. At this time, the depth of the spiral groove is 3mm and the groove width is 45mm.

[0066] The fourth cut begins from the retraction groove at the top of the blank, cutting from top to bottom. Taking the uncut surface of the blank as the zero point, the cut is 4mm deep. At this point, the depth of the spiral groove is 4mm and the groove width is 45mm.

[0067] The fifth cut begins from the retraction groove at the bottom of the billet, cutting from bottom to top. Taking the uncut surface of the billet as the zero point, the cut is 5mm deep. At this point, the spiral groove is 5mm deep and 45mm wide.

[0068] At this point, the first stage of cutting for the first spiral groove has been completed, and the worktable rotation center rotates at an angle equal to the angle between two spiral grooves.

[0069] In other words, 12 spiral grooves are machined on the surface of the blank, divided into three groups of four. Taking the first spiral groove as the reference, the second and third spiral grooves are skipped before machining the fourth spiral groove.

[0070] For example: the first group consists of the first, fourth, seventh, and tenth spiral grooves.

[0071] The second group consists of: the second spiral groove, the fifth spiral groove, the eighth spiral groove, and the eleventh spiral groove.

[0072] The third group consists of: the third spiral groove, the sixth spiral groove, the ninth spiral groove, and the twelfth spiral groove.

[0073] After processing the first group, the processing program will process the second group, and then the third group.

[0074] For example, the first group will machine the first spiral groove to a depth of 5mm, then machine the fourth spiral groove, then the seventh spiral groove, and finally the tenth spiral groove. At this point, the depth of all four spiral grooves in the first group will be 5mm, which means that the first stage of machining the spiral grooves in the first group has been completed. The machining program will then rotate the center of the worktable to machine the second group.

[0075] After the second set of four threaded grooves are machined in sequence, and the depth of each of the four spiral grooves in the second set is 5mm, the machining program will rotate the worktable to the center of rotation to process the third set after the first stage of machining the second set of spiral grooves is completed.

[0076] After the four threaded grooves in the third group are machined in sequence, and the depth of each of the four spiral grooves in the third group is 5mm, it means that the first stage of machining the spiral grooves in the third group has been completed. The machining program will then rotate the center of the worktable to machine the first group again.

[0077] The second stage of processing begins, where each spiral groove is machined to a depth of 10mm.

[0078] This process continues in the same manner, with each processing depth being 5mm. That is, the first processing depth is 5mm, the second processing depth is 10mm, the third processing depth is 15mm, and so on, until the depth of the 12 spiral grooves reaches 35mm, at which point the entire blank is processed.

[0079] When the machine tool rotates forward and the Y-axis movement speed is matched, the Y-axis completes the single groove machining from bottom to top. At this time, the Y-axis is at the top of the cylinder and rotates to another spiral groove. When the machine tool rotates backward and the Y-axis movement speed is matched, the Y-axis completes the single groove machining from top to bottom.

[0080] This machining method uses the same cutting tool as the groove width, avoiding the need for two cuts to machine each layer of the spiral groove to the required width. This prevents discrepancies between the groove width and the actual size caused by backlash inherent in the machine tool's rotary table. Furthermore, each cut in a single spiral groove layer is performed in one direction, further preventing backlash from causing deviations in the groove width.

[0081] Before processing, perform a trial cut of the single-head spiral groove on the outer circle of the blank using the above processing method, with a depth of 0.5-1mm. After processing, measure the actual value of the spiral groove width and compare it with the theoretical value to obtain the deviation value ΔL1. Then, calculate the deviation value ΔL1 according to the formula... The compensation angle θ is calculated, where θ1 is the helix angle, L2 is the lead, and ΔL1 is the slot width deviation. The compensation angle is added before the program segment of the reverse rotation machining from top to bottom of the rotary table to compensate for the reverse rotation clearance, ensuring that the machine tool's forward and reverse rotation machining are consistent.

[0082] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0083] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for machining multi-head ultra-large lead spiral grooves, characterized in that: The billet is hoisted onto the center of the workbench rotation, placed upright, and its axis is adjusted to coincide with the center of the workbench rotation. The workpiece is clamped to the rotation center of the rotary platform and the spiral groove is machined by rotating the workpiece and moving the Y-axis (rotating the rotation center of the workpiece causes the workpiece to rotate). A single-headed spiral shallow groove was test-cut on the outer circle of the blank, with one cut from top to bottom and another from bottom to top, with a depth of 0.5-1mm. After machining, the actual value of the spiral groove width was measured and compared with the theoretical value to obtain the deviation value ΔL1. The deviation value ΔL1 was then calculated according to the formula... The compensation angle θ is calculated, where θ1 is the helix angle, L2 is the lead, and ΔL1 is the slot width deviation value. The compensation angle θ is added to the machining program before the table reverse rotation command via the CNC system's rotary coordinate system transformation command. The entire machining program for the spiral groove is divided into program segments according to the rotation of the rotary table every 90°, and executed sequentially. The multi-start spiral groove is milled by CNC linkage between the rotation of the table (B-axis) and the longitudinal movement of the boring machine milling head (Y-axis). The multi-head spiral groove is processed by a combination of interval processing and layered cutting. First, a groove is processed with two grooves in between. Each groove is cut multiple times to the final depth of 35mm, with each cut depth being 5mm. This process is repeated until all spiral grooves are processed to the target size.

2. The method for machining multi-head ultra-large lead spiral grooves according to claim 1, characterized in that: The multi-head spiral groove is a 12-head spiral groove, and the groove skipping process is carried out by skipping two groove positions.

3. The method for machining multi-head ultra-large lead spiral grooves according to claim 2, characterized in that: The billet is divided into three parts, including a fixing ring, a relief groove, and a spiral groove. The fixing ring is located at both ends of the billet, and two relief grooves are formed between the two fixing rings. A spiral groove is formed between the two relief grooves.

4. The method for machining multi-head ultra-large lead spiral grooves according to claim 3, characterized in that: The spiral groove method is divided into two types. One cutting method is: the tool diameter is greater than half the groove width. The method adopts a layered alternating cutting method. When cutting each layer, the tool first cuts on one side of the groove and then moves to the other side to cut. The tool paths on both sides have an overlapping area in the groove width direction.

5. The method for machining multi-head ultra-large lead spiral grooves according to claim 4, characterized in that: The width of the overlapping area is: 2 × tool diameter - groove width.

6. The method for machining multi-head ultra-large lead spiral grooves according to claim 4, characterized in that: Another cutting method is as follows: when the diameter of the milling cutter is equal to the width of the spiral groove, a single spiral groove is machined by a unidirectional continuous cutting method. The rotary table rotates continuously in one direction, and the Y-axis moves in coordination to complete the cutting of one layer of a single spiral groove in one go.

7. The method for machining multi-head ultra-large lead spiral grooves according to claim 6, characterized in that: The depth of a single spiral groove completed in one go is 5mm.

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