High-precision indexing device and method for long-axis blind hole internal spline

Abstract

This invention discloses a high-precision indexing machining device and method for long-shaft blind-hole internal splines. The device includes a gantry machining center, which comprises a worktable and a spindle; a milling head, which is right-handedly Z-shaped with a 90° bend; a forming cutter, mounted on the output end of the milling head and corresponding to the inner wall of the blind hole; an outer circular indexing clasp, which is sleeved on the blind hole end of the long-shaft workpiece and detachably connected to it. Multiple pin holes are radially formed on the outer circumference of the outer circular indexing clasp, the number of which is equal to the number of teeth in the internal spline of the long-shaft workpiece. The center lines of the multiple pin holes correspond one-to-one with the indexing center lines of the multiple tooth grooves of the internal spline to be machined; and an indexing verification component, comprising a pin bar and an indexing indicator. This invention externalizes the reference by using a combination of the outer circular indexing clasp, pin bar, and indexing indicator, allowing direct reading from the indexing indicator for quantitative judgment, thus achieving ultra-high precision indexing control of the internal spline.

Description

Technical Field

[0001] This invention relates to the field of spline machining technology, specifically to a high-precision indexing machining device and method for internal splines in blind holes of long shafts. Background Technology

[0002] In the manufacturing of large screws, helical rotors and other long shaft parts (with lengths exceeding 8 meters), it is often necessary to machine high-precision internal splines in the blind holes on their end faces to achieve torque transmission.

[0003] Gear shaping is a common machining method for splines within blind holes. A gear shaping cutter performs a reciprocating cutting motion inside the blind hole, with the help of an indexing mechanism to shape each tooth sequentially. Gear shaping machines are vertical machine tools, requiring the workpiece to be mounted vertically or horizontally near the worktable. Taking a typical gear shaping machine, the Y54, as an example, its maximum longitudinal movement of the tool post is only 510mm; even large CNC gear shaping machines generally have a maximum machining tooth width of around 300mm. For long shaft workpieces exceeding 8 meters in length, existing gear shaping machines cannot accommodate clamping, let alone complete gear shaping of blind holes on the end face. Furthermore, gear shaping in deep blind holes is extremely difficult in terms of tool setting and measurement, usually relying on operator experience, making it difficult to guarantee machining accuracy, resulting in low yield. Additionally, it requires pre-cutting a retractable and chip-removing annular groove inside the blind hole, increasing the machining process and difficulty. Summary of the Invention

[0004] The purpose of this invention is to provide a high-precision indexing machining device and method for long-shaft blind hole internal splines, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides a high-precision indexing machining device and method for long-shaft blind hole internal splines, comprising:

[0006] A gantry machining center includes a worktable and a spindle. The worktable is used to clamp long shaft workpieces, and the spindle is used to provide cutting power.

[0007] A right-handed Z-shaped milling head with a 90° bend, the input end of which is detachably connected to the spindle, and the output end of which is located inside the blind hole of the long shaft workpiece;

[0008] A forming cutter is mounted on the output end of the milling head and corresponds to the inner wall of the blind hole;

[0009] An outer circular indexing circumference is provided, wherein the outer circular indexing circumference is sleeved on the blind hole end of the long shaft workpiece, and its inner circumferential surface is adapted to the outer surface of the long shaft workpiece. The outer circular indexing circumference is detachably connected to the long shaft workpiece. Multiple pin holes are radially provided on the outer circumference of the outer circular indexing circumference. The number of pin holes is equal to the number of teeth of the internal spline of the long shaft workpiece. The center lines of the multiple pin holes correspond one-to-one with the indexing center lines of the multiple tooth grooves of the internal spline to be machined.

[0010] The indexing verification component includes a pin and an indexing indicator. The pin is movably inserted into the pin hole, and the indexing indicator is detachably connected to the gantry machining center machine tool for cooperating with the pin to perform indexing verification on the tooth grooves of the internal spline.

[0011] Furthermore, the milling head is equipped with a spiral bevel gear pair for transmitting the torque of the spindle.

[0012] Furthermore, the graduation indicator is a lever micrometer, and the probe of the graduation indicator is spherical or flat.

[0013] A high-precision indexing machining method for long-shaft blind hole internal splines, using any of the above-mentioned high-precision indexing machining devices for long-shaft blind hole internal splines, includes the following steps:

[0014] S1. Clamp the long shaft workpiece on the worktable of the gantry machining center, align the outer circle and end face of the long shaft workpiece using a calibration table, take the center of the end face of the long shaft workpiece as the origin, set the blind hole axis of the long shaft workpiece to be parallel to the Z-axis of the gantry machining center, and establish the coordinate system of the long shaft workpiece.

[0015] S2. Install the right-hand Z-shaped 90° milling head on the spindle of the gantry machining center, so that its output end extends into the blind hole on the end face of the long shaft workpiece;

[0016] S3. Install the outer diameter indexing circlip on the outer surface of the end where the blind hole of the long shaft workpiece is located;

[0017] S4. Start the spindle of the gantry machining center and drive the milling head to machine the first internal spline groove from the bottom of the blind hole upwards. This is the reference groove. After machining, insert a high-precision cylindrical pin into the pin hole on the outer circle indexing ring corresponding to the reference groove that has passed the inspection with a spline plug gauge.

[0018] S5.1 Rotate the long shaft workpiece to the theoretical angular position of the next tooth groove to be machined;

[0019] S5.2 Install the indexing indicator on the bed or tooling clamping bracket of the gantry machining center that does not rotate with the long axis workpiece, use the probe of the indexing indicator to align with the pin hole position on the outer circle indexing ring corresponding to the tooth groove to be machined, and insert a pin bar into the pin hole of the tooth groove to be machined.

[0020] S5.3. Micro-rotate the long shaft workpiece and observe the reading of the indexing indicator. When the probe of the indexing indicator touches the outer circumferential surface of the pin inserted into the pin hole of the tooth groove to be processed and reaches the maximum runout value, or when the probe of the indexing indicator just slides past the top of the outer circumference of the pin and the pointer returns to the point, confirm that the indexing angle of the tooth groove is in precise position.

[0021] S5.4 After locking the long shaft workpiece, start the spindle of the gantry machining center to drive the milling head to process the tooth groove;

[0022] S5.5 Repeat steps S5.1-S5.4 to complete the machining of all internal spline grooves in sequence;

[0023] S6. After all the internal spline grooves are machined, insert a pin into each pin hole of the outer diameter indexing circlip, and use an indexing indicator to check the position of each pin in turn to verify the spline indexing accuracy.

[0024] Furthermore, in step S3, a cylindrical surface that precisely matches the inner circumferential surface of the outer diameter indexing ring is machined on the outer diameter surface of the end of the long shaft workpiece where the blind hole is located, and the outer diameter indexing ring is fixed on the cylindrical surface by interference fit or key connection.

[0025] Further, in step S4, after inserting a high-precision cylindrical pin into the pin hole corresponding to the reference tooth groove of the outer circular indexing circlip, the indexing indicator is installed on the bed or tooling clamping bracket of the gantry machining center machine tool that does not rotate with the long shaft workpiece, and the probe of the indexing indicator is brought into contact with the highest radial point of the pin to measure the maximum runout value.

[0026] Furthermore, when the machining module of the internal spline is ≥5, after the pin hole of the tooth groove to be machined is checked, the corresponding pin holes at the symmetrical locations of the pin holes of the tooth groove to be machined are checked again by repeating steps S5.2 and S5.3.

[0027] Furthermore, the angular correspondence between the multiple pin holes on the outer cylindrical indexing circlip and the multiple tooth grooves of the inner spline is ensured by the simultaneous machining of the multiple tooth grooves of the inner spline and the multiple pin holes of the outer cylindrical indexing circlip in the same clamping operation under the same long shaft workpiece coordinate system on the gantry machining center.

[0028] The beneficial effects of this invention are as follows: This invention uses a gantry machining center and a milling head to enable horizontal clamping of long-shaft workpieces, which is not limited by the tool stroke. At the same time, the combination of an external cylindrical indexing circlip, pin bar and indexing indicator externalizes the reference, and the indexing indicator is directly read for quantitative judgment. Moreover, it does not rely solely on the accuracy of the machine tool encoder or optical indexing head, and achieves ultra-high precision indexing control of internal splines, eliminating the cumulative error of machine tool indexing and the workpiece torsional deformation error. Attached Figure Description

[0029] Figure 1 This is a partial cross-sectional view of a milling head extending into a blind hole to machine a spline, according to an embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram of the long shaft workpiece and the internal spline structure of the blind hole according to an embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram of the outer circle indexing ring according to an embodiment of the present invention.

[0032] Figure 4 This is a schematic diagram of the indexing state of the calibration pin position of the indexing indicator table according to an embodiment of the present invention.

[0033] Figure 5 This is a flowchart of the processing method according to an embodiment of the present invention.

[0034] The components include: 1. Machine tool spindle; 2. Long shaft workpiece; 3. Milling head; 4. Forming cutter; 5. External diameter indexing circlip; 6. Pin; 7. Indexing indicator.

[0035] 21. Internal spline; 51. Pin hole. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely one embodiment of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0037] To make the objectives, technical solutions and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments.

[0038] In the following description, references to "an embodiment," "an embodiment," "an example," "example," etc., indicate that the described embodiment or example may include a particular feature, structure, characteristic, property, element, or limitation, but not every embodiment or example necessarily includes that particular feature, structure, characteristic, property, element, or limitation. Furthermore, the repeated use of the phrase "an embodiment according to this application," while possibly referring to the same embodiment, does not necessarily refer to the same embodiment.

[0039] like Figures 1-5 As shown, this invention discloses a high-precision indexing machining device for a long-axis blind hole internal spline 21, which includes:

[0040] The gantry machining center consists of a worktable and a spindle 1. The worktable is used to clamp long-shaft workpieces 2, and the spindle 1 is used to provide cutting power. The open-type long-stroke gantry machining center has no limitations on the bed and tool post structure of traditional gear shapers, and can easily accommodate long-shaft workpieces 2. The workpiece clamping rigidity can be guaranteed by multiple sets of auxiliary supports, which completely solves the fatal problem that conventional gear shapers cannot clamp ultra-long shafts.

[0041] The milling head 3 is a right-handed Z-shaped bend of 90°. The input end of the milling head 3 is detachably connected to the spindle 1, and the output end of the milling head 3 is located inside the blind hole of the long shaft workpiece 2. That is, the axis of the output end of the milling head 3 is parallel to the axis of the spindle 1 and offset by a certain distance, so that the output end of the milling head 3 can extend into the blind hole of the end face of the long shaft workpiece 2.

[0042] The forming cutter 4 is installed at the output end of the milling head 3 and corresponds to the inner wall of the blind hole. When the output end of the milling head 3 is close to the inner wall of the blind hole, the forming cutter 4 can mill the inner wall of the blind hole under the drive of the milling head 3, thereby realizing the complete machining of the spline 21 inside the blind hole.

[0043] An outer circular indexing clasp 5 is fitted onto the blind hole end of the long shaft workpiece 2, and its inner circumferential surface is adapted to the outer surface of the long shaft workpiece 2. The outer circular indexing clasp 5 is detachably connected to the long shaft workpiece 2. Multiple pin holes 51 are radially opened on the outer circumference of the outer circular indexing clasp 5. The number of pin holes 51 is equal to the number of teeth of the inner spline 21 of the long shaft workpiece 2. The center lines of the multiple pin holes 51 correspond one-to-one with the indexing center lines of the multiple tooth grooves of the inner spline 21 to be processed. In the embodiment, the indexing indicator 7 can be a dial indicator or a micrometer indicator.

[0044] On the outer circumference of the outer cylindrical indexing circumference 5, an equal number of pin holes 51 are drilled evenly according to the number of teeth of the machined internal spline 21. The center angle position of each pin hole 51 corresponds one-to-one with the indexing centerline of an internal spline 21 tooth groove. Then, the pre-machined high-precision outer cylindrical indexing circumference 5 is fitted onto the outer circumference of the blind hole end of the long shaft workpiece 2, ensuring that the inner hole and the outer cylindrical surface of the long shaft workpiece 2 are completely in contact. In this way, the angular position of each spline tooth groove inside the blind hole is mapped to the corresponding pin hole 51 on the outside of the long shaft workpiece 2. The invisible spline tooth groove position inside the blind hole is converted into the visible and tangible pin hole 51 position on the outer cylindrical indexing circumference 5, realizing the externalization of the indexing reference.

[0045] The indexing calibration component includes a pin 6 and an indexing indicator 7. The pin 6 is movably inserted into the pin hole 51, and the indexing indicator 7 is detachably connected to the gantry machining center machine tool. It is used to cooperate with the pin 6 to perform indexing calibration on the tooth groove of the internal spline 21.

[0046] This scheme uses a combination of the scale indicator 7 and the pin 6 for physical verification, specifically:

[0047] A unified measurement benchmark is established using the pin hole 51 corresponding to the qualified reference tooth groove as the zero point. Before machining each tooth groove, the indexing angle of the tooth groove is precisely calibrated using a mechanical alignment method with the pin bar 6 and the indexing indicator 7 to correct the theoretical indexing error. Furthermore, the indexing of each tooth groove is independently verified, eliminating the cumulative error of machine tool indexing and the workpiece torsional deformation error. The indexing accuracy is determined solely by the accuracy of the pin hole 51 of the outer cylindrical indexing circlip 5 and the accuracy of the measurement system, unaffected by the workpiece length and independent of the operator's experience. This accuracy is far superior to that achieved by relying solely on machine tool encoders or optical indexing heads, and is particularly suitable for compensating for torsional deformation of ultra-long shafts.

[0048] This invention employs a gantry machining center and a milling head 3 to allow the long-shaft workpiece 2 to be horizontally clamped without being limited by the tool travel. At the same time, the combination of an external circular indexing circlip 5, a pin 6, and an indexing indicator 7 externalizes the reference, allowing direct reading from the indexing indicator 7 for quantitative judgment. This achieves ultra-high precision indexing control of the internal spline 21 without relying solely on the accuracy of the machine tool encoder or optical indexing head, thus eliminating the cumulative error of machine tool indexing and the workpiece torsional deformation error.

[0049] In one embodiment, the milling head 3 is internally equipped with a spiral bevel gear pair for transmitting the torque of the spindle 1. Specifically, the input end of the milling head 3 is connected to the spindle 1 via a standard machine tool taper shank. When the spindle 1 rotates, the driving spiral bevel gear at the input end drives the driven spiral bevel gear meshing with it, resulting in the output end obtaining a rotational motion that is equal in speed and perpendicular in direction to the spindle 1. Compared with straight bevel gear pairs, it has the advantages of smooth meshing, high load-bearing capacity, and small transmission error, which can ensure the stability of tool rotation and machining accuracy in deep blind hole machining.

[0050] In one embodiment, the graduation indicator 7 is a lever dial indicator with a graduation value of up to 0.002 mm to capture micron-level angular position changes. The probe of the graduation indicator 7 is spherical or flat to reduce frictional errors when in contact with the pin 6. Using a spherical probe ensures point contact with the outer circumference of the pin 6, resulting in low frictional resistance and suitability for high-speed micro-motion alignment; using a flat probe provides stable surface contact, suitable for applications requiring greater contact pressure. Users can flexibly choose the appropriate probe based on on-site accuracy requirements and surface roughness.

[0051] A high-precision indexing machining method for a long-shaft blind hole internal spline 21, using any of the above-mentioned high-precision indexing machining devices for long-shaft blind hole internal splines 21, includes the following steps:

[0052] S1. Mount the long shaft workpiece 2 on the worktable of the gantry machining center. Align the outer circle and end face of the long shaft workpiece 2 with the calibration table. With the center of the end face of the long shaft workpiece 2 as the origin, set the blind hole axis of the long shaft workpiece 2 to be parallel to the Z-axis of the gantry machining center and establish the coordinate system of the long shaft workpiece 2.

[0053] In this embodiment, the gantry machining center also includes a pressure plate to hoist the long-shaft workpiece 2 onto the worktable of the gantry machining center and fix it with the pressure plate. A dial indicator is used to align the workpiece along the axial and radial directions of its outer circle. The center of the blind hole end of the long-shaft workpiece 2 is taken as the origin, and the centerline of the blind hole is set to be completely parallel to the Z-axis of the machine tool. The machining coordinate system of the long-shaft workpiece 2 is established, and the zero point of the fourth axis (rotation axis) of the gantry machining center is calibrated to ensure that the rotation axis is coaxial with the centerline of the workpiece.

[0054] S2. Install the right-hand Z-shaped 90° milling head 3 on the spindle 1 of the gantry machining center, so that its output end extends into the blind hole on the end face of the long shaft workpiece 2;

[0055] S3. Install the outer circle indexing ring 5 on the outer surface of the end where the blind hole of the long shaft workpiece 2 is located;

[0056] S4. Start the spindle 1 of the gantry machining center and drive the milling head 3 to process the first internal spline 21 tooth groove from the bottom of the blind hole upwards using a plunge milling or spiral milling method. This is the reference tooth groove. After the machining is completed, insert a high-precision cylindrical pin 6 into the pin hole 51 on the outer circle indexing circlip 5 corresponding to the reference tooth groove that has passed the inspection with a spline plug gauge.

[0057] In a specific embodiment, cutting parameters such as spindle speed and feed rate can be set. The spindle 1 is started to drive the forming cutter 4 to rotate at high speed. The machine tool Z-axis drives the milling head 3 to make a linear feed from the bottom of the blind hole to the hole opening. The first tooth groove (reference tooth groove) is machined in one pass. After the machining is completed, the tool is withdrawn. The tooth profile and tooth direction accuracy of the reference tooth groove are checked with a high-precision spline plug gauge. After the inspection is qualified, a high-precision cylindrical pin 6 is inserted into the retaining ring pin hole 51 corresponding to the tooth groove.

[0058] S5.1 Rotate the long shaft workpiece 2 to the theoretical angular position of the next tooth groove to be processed; in the embodiment, the rotation of the long shaft workpiece 2 is achieved by the machine tool rotary table.

[0059] S5.2 Install the indexing indicator 7 on the bed or tooling clamping bracket of the gantry machining center that does not rotate with the long shaft workpiece 2, use the probe of the indexing indicator 7 to align with the pin hole 51 on the outer circle indexing circlip 5 corresponding to the tooth groove to be machined, and at the same time insert the pin 6 into the pin hole 51 of the tooth groove to be machined.

[0060] In this embodiment, the indexing indicator 7 includes a magnetic base and an indicator body. The indexing indicator 7 can be fixed to the bed or tooling clamping bracket of a gantry machining center machine tool that does not rotate with the long axis workpiece 2 via the magnetic base, so that the probe of the indexing indicator 7 is aligned with the pin hole 51 on the retaining ring corresponding to the tooth groove to be machined.

[0061] S5.3. Micro-rotate the long shaft workpiece 2 while observing the reading of the indexing indicator 7. When the probe of the indexing indicator 7 touches the outer circumferential surface of the pin 6 inserted into the pin hole 51 of the tooth groove to be processed and reaches the maximum runout value, or when the probe of the indexing indicator 7 just slides past the top of the outer circumference of the pin 6 and the pointer returns to its original position, confirm that the indexing angle of the tooth groove is accurately in place. Use the handwheel or manual mode to micro-rotate the machine tool table. When the pointer gradually increases, it indicates that the probe is approaching the highest point of the pin 6. Move the machine tool table back to the position of the maximum pointer reading. At this time, the reading of the indexing indicator 7 is the maximum runout value of the tooth.

[0062] S5.4 After locking the long shaft workpiece 2, start the spindle 1 of the gantry machining center and drive the milling head 3 to process the tooth groove; after confirming that the indexing angle is in place, immediately lock the machine tool rotary table (i.e. the fourth axis of the machine tool), maintain the cutting parameters that are completely consistent with the reference tooth groove, start the spindle 1, and the machine tool Z axis drives the milling head 3 to complete the milling of the tooth groove. After the machining is completed, remove the tool and perform intermediate sampling inspection by spline plug gauge.

[0063] S5.5 Repeat steps S5.1-S5.4 to complete the machining of all internal spline 21 tooth grooves in sequence;

[0064] S6. After all the internal spline 21 tooth grooves are machined, insert the pin 6 into each pin hole 51 of the outer diameter indexing circlip 5, and use the indexing indicator 7 to check the position of each pin 6 in turn to verify the spline indexing accuracy.

[0065] After all the tooth grooves are machined, without disassembling the workpiece and the outer diameter indexing circlip 5, insert high-precision pins 6 into each pin hole 51 of the outer diameter indexing circlip 5 in sequence. Use the indexing indicator 7 to check the reading of the highest point of each pin 6 in sequence, record the total indexing deviation, and verify whether the spline indexing accuracy meets the design requirements. After the inspection is qualified, disassemble the tooling and remove the workpiece in sequence to complete the entire process.

[0066] In this solution, even if there are gaps or errors in the machine tool's rotary table, the actual angular position of the workpiece can be directly verified using the external indexing indicator table 7, eliminating transmission chain errors. Simultaneously, the indexing accuracy can be verified at any time during machining without disassembling the workpiece; and it can be directly used as a final inspection method after machining.

[0067] In one embodiment, in step S3, a cylindrical surface that precisely matches the inner circumferential surface of the outer diameter indexing ring 5 is machined on the outer diameter surface of the long shaft workpiece 2 at the end where the blind hole is located, and the outer diameter indexing ring 5 is fixed on the cylindrical surface by interference fit or key connection.

[0068] When the outer circular indexing retaining ring 5 is fixed to the cylindrical surface by interference fit, the interference fit is 0.02-0.04mm. The heat fitting method can be used, that is, the retaining ring is heated to 200℃-250℃, causing its inner hole to expand and fit into the cylindrical surface of the long shaft workpiece 2. After cooling, it shrinks and tightens, which is suitable for permanent or semi-permanent fixation.

[0069] When the outer diameter indexing retaining ring 5 needs to be detachable, a key connection method is adopted. A keyway is machined on the cylindrical surface, and a key is set at the corresponding position of the outer diameter indexing retaining ring 5. It is axially pressed with screws, which is suitable for scenarios that require repeated disassembly and assembly of the retaining ring.

[0070] In one embodiment, in step S4, after inserting a high-precision cylindrical pin 6 into the pin hole 51 corresponding to the reference tooth groove of the outer circular indexing circlip 5, the indexing indicator 7 is installed on the bed or tooling clamping bracket of the gantry machining center machine tool that does not rotate with the long shaft workpiece 2, and the probe of the indexing indicator 7 is brought into contact with the highest radial point of the pin 6 to measure the maximum runout value.

[0071] The reference tooth groove is a qualified tooth groove that has been actually machined, and its indexing centerline is the true indexing reference of the internal spline 21. The outer diameter indexing circlip 5 is fixed to the long shaft workpiece 2, and the centerline of the corresponding pin hole 51 is strictly coplanar with the indexing centerline of the reference tooth groove. After the high-precision cylindrical pin 6 is inserted into the pin hole 51, the line connecting its radial highest point is the projection of the indexing centerline of the reference tooth groove onto the outer diameter of the workpiece. The indexing indicator 7 is fixed on the stationary part of the machine tool, and its probe position is an absolutely fixed point in space. When the radial highest point of the pin 6 contacts the probe, this position is the zero point of the indexing reference. The indexing of all subsequent tooth grooves is referenced to this point and is independent of the initial zero point of the fourth axis of the machine tool. After this zero point is established, the fourth axis of the machine tool is only used as a coarse positioning tool. Moreover, the maximum runout value here can be used as a reference zero point for the verification of subsequent indexed tooth grooves, or as a reference value for calculating the indexing error. It replaces the electronic reference with a mechanical reference, and uses the machined reference tooth groove as the physical origin to establish an absolute indexing reference independent of the machine tool encoder, thus isolating the influence of machine tool transmission error, workpiece clamping error, and snap ring installation error.

[0072] In one embodiment, when the machining module of the internal spline 21 is ≥5, after the verification of the pin hole 51 of the tooth groove to be machined is completed, the operation steps S5.2 and S5.3 are repeated for auxiliary verification of the corresponding pin hole 51 at the symmetrical position of the pin hole 51 of the tooth groove to be machined.

[0073] A large module means larger spline teeth and greater cutting force. When the milling head 3 mills a single-sided tooth groove, the cutting force will cause slight twisting or displacement of the workpiece, which may result in a unilateral clearance between the machine tool rotary table or the long shaft workpiece 2 and the outer cylindrical indexing circlip 5. Checking only the pin hole 51 corresponding to the tooth groove to be machined may not detect the deviation in the symmetrical direction. By simultaneously checking the pin holes 51 on the symmetrical side, it can be determined whether the long shaft workpiece 2 has an overall angular drift or eccentricity, thus enabling bidirectional compensation.

[0074] The specific operation is as follows: After the pin hole 51 of the tooth groove to be machined is checked, the same check operation is repeated for the pin hole 51 at the symmetrical location of the tooth groove, that is, the pin bar 6 is inserted into the pin hole 51 at the symmetrical location and the maximum runout value is found using the indexing indicator 7. When both pin holes 51 reach the same maximum runout value corresponding to the reference tooth, the indexing angle is confirmed to be accurate. If there is a difference on both sides, the long shaft workpiece 2 is finely adjusted until the readings on both sides meet the requirements simultaneously. This method can effectively eliminate the indexing error caused by the workpiece being subjected to force on one side or the rotational clearance.

[0075] In one embodiment, the angular correspondence between the multiple pin holes 51 on the outer circular indexing circlip 5 and the multiple tooth grooves of the inner spline 21 is ensured by the simultaneous machining of the multiple tooth grooves of the inner spline 21 and the multiple pin holes 51 of the outer circular indexing circlip 5 in the same clamping operation of the long shaft workpiece 2 in the same coordinate system of the long shaft workpiece 2 on the gantry machining center machine tool.

[0076] The long-shaft workpiece 2 is clamped along the Z-axis of the gantry machining center, and the outer diameter indexing circlip 5 is fixed to the long-shaft workpiece 2, forming an inseparable whole. All clamping plates and auxiliary support mechanisms of the long-shaft workpiece 2 are locked, and the workpiece clamping is not loosened throughout the entire process. The rotation of the long-shaft workpiece 2 is completed via the machine tool's rotary table until all pin holes 51 and tooth grooves are machined. That is, all machining is performed in the same workpiece coordinate system of the gantry machining center, by the same machining center, and with the same program. The indexing angle of the inner spline 21 tooth groove and the indexing angle of the outer diameter indexing circlip 5 pin holes 51 are directly guaranteed by the same rotational motion of the machine tool's fourth axis (the machine tool's rotary table).

[0077] The specific implementation examples are as follows:

[0078] The machining method for a spiral rotor with a length of 8 meters, a blind hole diameter of 292 mm on the end face, 21 internal splines with a module of 7.5 mm, and 39 teeth is as follows:

[0079] S1. On the outer circular surface of the blind hole end of the rotor, a cylindrical surface that is precisely matched with the outer circular indexing ring 5 is precision machined. Then, the rotor is hoisted onto the worktable of the gantry machining center and fixed with a pressure plate. The runout of the outer circle is leveled to ≤0.02mm. With the center of the workpiece end face as the origin, the center line of the blind hole is made parallel to the Z-axis of the machine tool. The workpiece coordinate system is set, and the coordinate system is recorded and locked in the machine tool control system.

[0080] S2. Install a Z-shaped 90° milling head 3 on the spindle 1 of the gantry machining center. Its output end diameter is 250mm and it can extend into the blind hole to a depth of 600mm. Install a forming cutter 4 with a module of 7.5mm.

[0081] S3. Machining an outer cylindrical indexing ring 5 with an outer diameter of 466mm and an inner diameter that mates with the cylindrical surface of the workpiece. Machining 39 pin holes 51 with a diameter of 16mm evenly distributed on the outer cylindrical indexing ring 5, with a hole position accuracy requirement of ±0.01mm. Then heat-fitting the outer cylindrical indexing ring 5 onto the cylindrical surface of the workpiece, with an interference fit of 0.02-0.04mm.

[0082] S4. Set the cutting parameters such as spindle speed and feed rate of spindle 1, start spindle 1 to drive the milling head 3 and the forming cutter 4 to rotate at high speed, and machine the first spline tooth groove (reference tooth groove). After machining, use a spline plug gauge to check and confirm that the tooth groove size and shape are qualified.

[0083] Insert a φ16h6 cylindrical pin 6 into the pin hole 51 corresponding to the reference tooth groove on the outer circular indexing ring 5. Attach the lever micrometer to the machine tool bed via a magnetic base (it does not rotate with the workpiece). Adjust the probe so that the center of the probe ball is on the same horizontal plane as the axis of the pin 6, and the probe is radially perpendicular to the pin 6. Adjust the spherical probe to lightly contact the highest radial point of the pin 6, causing the lever micrometer pointer to read a value. Record this value; it is the maximum runout value. This value serves as the reference benchmark for subsequent indexing calibration of each tooth groove. Furthermore, the lever micrometer is only installed after machining or during pre-machining inspection; it is not installed during machining, and the pin does not interfere with machining.

[0084] S5.1 Rotate the workpiece 9.231° (360° / 39°) using the machine tool's rotary table. This completes the theoretical pre-positioning of the second tooth groove to be machined.

[0085] S5.2 Insert the second pin 6 into the pin hole 51 (second tooth pin hole 51) on the outer circular indexing circlip 5 that corresponds to the tooth groove to be machined. The lever dial indicator (graduation value 0.002mm) is attached to the machine tool bed by a magnetic base (it does not rotate with the workpiece).

[0086] S5.3. Using the probe of a dial indicator, touch the second pin 6 at the position of the second tooth pin hole 51. Manually fine-tune the angle of the machine tool's rotary table to adjust the workpiece angle, observing the dial indicator reading until the pointer reaches the same reading at the highest point of the pin 6, confirming the correct position. Additionally, insert the pin 6 into the pin hole 51 at the symmetrical location and use the dial indicator to calibrate the maximum runout value. When both pin holes 51 reach the same maximum runout value corresponding to the reference tooth, confirm the indexing angle is accurately in place. If there is a difference on both sides, fine-tune the long shaft workpiece 2 until the readings on both sides simultaneously meet the requirements, confirming the correct position.

[0087] S5.4 After confirming the position, lock the machine tool rotary table, start spindle 1, and mill the second tooth groove.

[0088] S5.5 Repeat the above steps until all 39 tooth grooves are completed.

[0089] S6. After all tooth grooves are machined, without disassembling the workpiece and the outer diameter indexing circlip 5, insert φ16h6 pins 6 sequentially into the 39 pin holes 51. Use a lever dial indicator to check all pins 6 sequentially and record all data. Calculate the difference between the maximum and minimum readings to obtain the cumulative pitch error. Confirm that the cumulative pitch error is ≤0.03mm, achieving GB / T 3478.1 Grade 5 accuracy.

[0090] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-precision indexing machining device for long-shaft blind hole internal splines, characterized in that: include: A gantry machining center includes a worktable and a spindle. The worktable is used to clamp long shaft workpieces, and the spindle is used to provide cutting power. A right-handed Z-shaped milling head with a 90° bend, the input end of which is detachably connected to the spindle, and the output end of which is located inside the blind hole of the long shaft workpiece; A forming cutter is mounted on the output end of the milling head and corresponds to the inner wall of the blind hole; An outer circular indexing circumference is provided, wherein the outer circular indexing circumference is sleeved on the blind hole end of the long shaft workpiece, and its inner circumferential surface is adapted to the outer surface of the long shaft workpiece. The outer circular indexing circumference is detachably connected to the long shaft workpiece. Multiple pin holes are radially provided on the outer circumference of the outer circular indexing circumference. The number of pin holes is equal to the number of teeth of the internal spline of the long shaft workpiece. The center lines of the multiple pin holes correspond one-to-one with the indexing center lines of the multiple tooth grooves of the internal spline to be machined. The indexing verification component includes a pin and an indexing indicator. The pin is movably inserted into the pin hole, and the indexing indicator is detachably connected to the gantry machining center machine tool for cooperating with the pin to perform indexing verification on the tooth grooves of the internal spline.

2. The high-precision indexing machining device for long-shaft blind hole internal splines according to claim 1, characterized in that: The milling head is equipped with a spiral bevel gear pair for transmitting the torque of the spindle.

3. The high-precision indexing machining device for long-shaft blind hole internal splines according to claim 1, characterized in that: The graduated indicator is a lever micrometer, and the probe of the graduated indicator is spherical or flat.

4. A high-precision indexing machining method for long-shaft blind hole internal splines, using the high-precision indexing machining device for long-shaft blind hole internal splines according to any one of claims 1-3, characterized in that: Includes the following steps: S1. Clamp the long shaft workpiece on the worktable of the gantry machining center, align the outer circle and end face of the long shaft workpiece using a calibration table, take the center of the end face of the long shaft workpiece as the origin, set the blind hole axis of the long shaft workpiece to be parallel to the Z-axis of the gantry machining center, and establish the coordinate system of the long shaft workpiece. S2. Install the right-hand Z-shaped 90° milling head on the spindle of the gantry machining center, so that its output end extends into the blind hole on the end face of the long shaft workpiece; S3. Install the outer diameter indexing circlip on the outer surface of the end where the blind hole of the long shaft workpiece is located; S4. Start the spindle of the gantry machining center and drive the milling head to machine the first internal spline groove from the bottom of the blind hole upwards. This is the reference groove. After machining, insert a high-precision cylindrical pin into the pin hole on the outer circle indexing ring corresponding to the reference groove that has passed the inspection with a spline plug gauge. S5.1 Rotate the long shaft workpiece to the theoretical angular position of the next tooth groove to be machined; S5.2 Install the indexing indicator on the bed or tooling clamping bracket of the gantry machining center that does not rotate with the long axis workpiece, use the probe of the indexing indicator to align with the pin hole position on the outer circle indexing ring corresponding to the tooth groove to be machined, and insert a pin bar into the pin hole of the tooth groove to be machined. S5.

3. Micro-rotate the long shaft workpiece and observe the reading of the indexing indicator. When the probe of the indexing indicator touches the outer circumferential surface of the pin inserted into the pin hole of the tooth groove to be processed and reaches the maximum runout value, or when the probe of the indexing indicator just slides past the top of the outer circumference of the pin and the pointer returns to the point, confirm that the indexing angle of the tooth groove is in precise position. S5.4 After locking the long shaft workpiece, start the spindle of the gantry machining center to drive the milling head to process the tooth groove; S5.5 Repeat steps S5.1-S5.4 to complete the machining of all internal spline grooves in sequence; S6. After all the internal spline grooves are machined, insert a pin into each pin hole of the outer diameter indexing circlip, and use an indexing indicator to check the position of each pin in turn to verify the spline indexing accuracy.

5. The high-precision indexing machining method for a long-shaft blind hole internal spline according to claim 4, characterized in that: In step S3, a cylindrical surface that precisely matches the inner circumference of the outer diameter indexing circumference is machined on the outer diameter surface of the end of the long shaft workpiece where the blind hole is located, and the outer diameter indexing circumference is fixed on the cylindrical surface by interference fit or key connection.

6. The high-precision indexing machining method for a long-shaft blind hole internal spline according to claim 4, characterized in that: In step S4, after inserting a high-precision cylindrical pin into the pin hole corresponding to the reference tooth groove of the outer circular indexing circlip, the indexing indicator is installed on the bed or tooling clamping bracket of the gantry machining center machine tool that does not rotate with the long shaft workpiece, and the probe of the indexing indicator is brought into contact with the highest radial point of the pin to measure the maximum runout value.

7. The high-precision indexing machining method for a long-shaft blind hole internal spline according to claim 4, characterized in that: When the machining module of the internal spline is ≥5, after the pin hole of the tooth groove to be machined is checked, repeat the operation steps S5.2 and S5.3 for auxiliary check of the corresponding pin hole at the symmetrical position of the pin hole of the tooth groove to be machined.

8. A high-precision indexing machining method for a long-shaft blind hole internal spline according to claim 4, characterized in that: The angular correspondence between the multiple pin holes on the outer cylindrical indexing circlip and the multiple tooth grooves of the inner spline is ensured by the simultaneous machining of the multiple tooth grooves of the inner spline and the multiple pin holes of the outer cylindrical indexing circlip in the same clamping operation of the long shaft workpiece in the same long shaft workpiece coordinate system on the gantry machining center.

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