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CN-121988994-A - Method for improving machining precision of internal gear

CN121988994ACN 121988994 ACN121988994 ACN 121988994ACN-121988994-A

Abstract

The invention discloses a method for improving machining precision of an internal gear, which comprises the following steps of S1, material preparation, S2, rough machining, S3, heat treatment, S4, semi-finishing of a tooth blank, S5, rough tooth shaping of the tooth blank, S6, surface hardening, S7, finishing of the tooth blank, S8, slow wire feeding, S9, polishing and deburring, S10, and fluid polishing. According to the invention, the manufacturing precision and the production efficiency of the high-precision gear can be obviously improved by optimizing the process route, and meanwhile, the production cost is reduced, so that the product quality is comprehensively optimized. The efficiency, cost and quality bottlenecks in the high-precision internal gear manufacturing process are fundamentally solved.

Inventors

  • YAO YONG
  • LI XIANYAO
  • Zhou Pengliang
  • CHEN HANBING
  • CHEN LONG

Assignees

  • 贵州航天群建精密机械有限公司

Dates

Publication Date
20260508
Application Date
20260316

Claims (10)

  1. 1. A method for improving machining precision of an internal gear is characterized by comprising the following steps of S1, preparing materials, S2, rough machining, S3, heat treatment, S4, semi-finishing of a tooth blank, S5, rough tooth shaping of the tooth blank, S6, surface hardening, S7, finishing of the tooth blank, S8, slow wire feeding, S9, polishing and deburring, S10, and fluid polishing.
  2. 2. The method for improving machining precision of the internal gear, as claimed in claim 1, wherein the S1 material preparation is specifically CF170 precipitation hardening stainless steel, and forging or precision casting is selected.
  3. 3. The method for improving machining precision of an internal gear according to claim 1, wherein the step S2 of rough machining is characterized in that the method for ensuring the basic shape and the dimensional stability of a tooth blank by adopting the uniform allowance of each appearance and the inner hole allowance is adopted, so that the hole size and the final size of the tooth blank after rough machining are controlled to be 1mm.
  4. 4. The method for improving the machining precision of the internal gear according to claim 2, wherein the S3 is characterized in that the heat treatment specifically comprises the steps of adopting a solid solution, aging and cold treatment mode to treat a CF170 stainless steel tooth blank, and the control process of each link is as follows: Solution treatment of The temperature is 980-1050 ℃, the heat preservation time is 3-9 h, and the cooling speed is 20-50 ℃ per second by air cooling or oil cooling; Aging The temperature window is 440-540 ℃, the retained austenite is controlled to be 5-15%, and the heat preservation time is 2-4 hours; cold treatment In a liquid nitrogen medium, the constant temperature is 80 ℃ to 100 ℃ for 1 to 2 hours.
  5. 5. The method for improving the machining precision of the internal gear according to claim 1, wherein the S4 semi-finishing of the tooth blank specifically comprises the following steps: S401, releasing and removing residual stress, namely reducing the residual stress in the tooth blank through vibration aging or heat treatment aging treatment; s402, removing the redundant size of the tooth blank, namely removing the redundant allowance after heat treatment through a milling process and a turning process, ensuring that the size of the tooth blank is close to a final design value, and reserving the allowance on a single side by 0.5-1 mm; S403, improving the surface roughness or oxidation problem, namely adopting sand blasting, acid washing or polishing technology to reduce the surface roughness from Ra6.3μm to Ra3.2μm and thoroughly removing oxide skin; S404, removing the hardening layer and the oxide layer, namely removing the surface hardening layer by cutting; s405, controlling machining allowance, namely reducing the size tolerance of the tooth blank from +/-0.05 mm to +/-0.01 mm according to the tooth tip 0.8mm and the tooth root 0.5mm which are reserved allowance for the shape differentiation of the tooth blank; S406, improving the processing efficiency, namely reducing the semi-finishing time compared with the traditional method by adopting a high-speed milling and strong turning efficient process.
  6. 6. The method for improving the machining precision of the internal gear according to claim 2, wherein the step S5 of machining the rough gear blank is characterized in that a numerical control gear shaping machine is adopted for gear shaping, and machining errors are reduced by optimizing gear shaping technological parameters: (1) Accurately controlling the feeding quantity to be 0.1-0.3 mm/tooth through a numerical control system; (2) Aiming at the CF170 material, the cutting speed is adjusted to be 70-100 m/min; (3) The clamping deformation is reduced by adopting a hydraulic clamp, so that the jump error of the gear ring is less than or equal to 0.03mm; (4) And compensating the thermal deformation and cutter abrasion of the machine tool in real time through numerical control.
  7. 7. The method for improving machining precision of an internal gear according to claim 1, wherein S6 is characterized in that the surface hardening treatment is specifically to improve the surface hardness of the gear by adopting an ion nitriding technology, so that the surface hardness of the gear is more than 60HRC, and the rest parts of the gear are subjected to protection treatment.
  8. 8. The method for improving the machining precision of the internal gear according to claim 1, wherein the step S7 of finishing the tooth blank specifically comprises the following steps: s701, establishing a finish machining reference, namely machining a high-precision process hole with the position degree less than or equal to 0.005mm on the end face of a tooth blank as the finish machining reference, and finishing tooth form, tooth direction and end face machining in one clamping by adopting a composite machining center; S702, clamping, positioning and controlling precision, namely realizing zero-clearance clamping of a workpiece by adopting a hydraulic expansion clamp through uniform pressure of 6-8MPa, wherein the positioning precision is +/-0.002 mm, adopting a hot clamping technology, enabling the temperature difference between the clamp and the workpiece to be less than or equal to 1 ℃, eliminating the influence of thermal deformation, carrying out laser interferometer calibration on 20 workpieces processed by CBN or diamond coating cutters, enabling the runout error of the cutters to be less than or equal to 0.003mm, replacing the cutters every 60, utilizing high-precision equipment with a grating rule with resolution of 0.001 mu, compensating the thermal deformation and mechanical error in real time, and dynamically adjusting cutting parameters through a temperature sensor and a force sensor.
  9. 9. The method for improving machining precision of the internal gear according to claim 2, wherein the S8 slow wire-moving machining specifically comprises the following steps: S801, ensuring the precision of a machine tool, namely adopting a high-precision slow wire-moving machine tool to ensure that the straightness of the machine tool is less than or equal to 0.002mm/m, the angle deviation is less than or equal to 1'', the tooth form error is less than or equal to 0.005mm, and controlling the thermal deformation error of the machine tool to be less than or equal to 0.003 mm/DEG C through a constant-temperature workshop and a thermal symmetry structure; S802, electrode wire selection and trimming, namely, selecting electrode wires with the diameter of 0.015-0.20 mm and the tension of 12-15N for CF170 materials, trimming the electrode wires by a single-point diamond pen with the tip radius of less than or equal to 0.05mm, so that the perpendicularity error of the electrode wires is less than or equal to 0.003mm, trimming 20 pieces per time, detecting the abrasion of the electrode wires by an acoustic emission sensor, forcibly replacing the electrode wires when the discharge current fluctuation exceeds 15%, detecting tooth shapes by a laser profiler, and ensuring that the tooth shape error is less than or equal to 0.005mm; S803, high-precision clamping, namely realizing positioning precision of +/-0.001 mm and clamping repeatability of less than or equal to 0.002mm by utilizing a hydraulic expansion axis with expansion pressure of 8-10 MPa, enabling radial runout of a gear ring to be less than or equal to 0.005mm by an end face positioning pin with diameter tolerance of +/-0.005 mm, adopting a pressure sensor to monitor clamping force in real time, avoiding workpiece deformation, and enabling hydraulic clamping time to be less than or equal to 30S; S804, optimizing processing parameters, namely setting discharge current of 5-20A, pulse width of 12-14 mu S, pulse interval of 12-14 mu S, wire feeding speed of 20mm/S and feeding speed of 0.005-0.01 mm/tooth for CF170 material, avoiding overburning and controlling tooth form error to be 0.005mm; s805, feeding, namely executing by using a process method of cutting for 1 time and repairing for 5 times in a reciprocating way; S806, cooling and chip removal, namely ensuring that the gear workpiece is effectively cooled and can be sufficiently washed and removed in the machining process, so that the allowance of the fine slow wire running in the direction of the common normal line of the gear is 0.10-0.15 mm.
  10. 10. The method for improving the machining precision of the internal gear according to claim 2, wherein the S9 step of finishing and deburring is specifically realized by adopting a combination mode of finishing equipment and manual deburring: (1) The chamfering size tolerance is controlled to +/-0.05 mm and the surface roughness is controlled to be less than or equal to 0.4 mu m through batch processing of finishing equipment; (2) Manually processing the fine parts of the tooth root and the key groove, and controlling the chamfer dimensional tolerance to +/-0.02 mm and the surface roughness Ra to be less than or equal to 0.4 mu m; The S10 is specifically characterized in that a fluid polishing process is adopted, a polishing solution containing alumina or silicon carbide abrasive particles is matched, the pressure is controlled to be 0.2-0.5 MPa, the flow rate is controlled to be 1-2 m/S, and the tooth surface is uniformly polished for 15-30 min.

Description

Method for improving machining precision of internal gear Technical Field The invention relates to a method for improving machining precision of an internal gear, and belongs to the technical field of gear machining and manufacturing. Background Gears are critical components in mechanical transmission systems, and their machining accuracy and surface roughness directly affect transmission efficiency, operating noise, and equipment life. Although the traditional internal gear processing method such as gear shaping and the like can meet certain precision requirements, the problems of insufficient processing precision and higher surface roughness still exist in the high-precision internal gear manufacturing. In the prior art, finish machining processes such as gear grinding, gear honing and the like are generally adopted to improve the precision and surface quality of gears, but the problems of low machining efficiency, high cost, poor suitability for internal gears and the like exist in the methods. Aiming at the pain points of the above industries, the invention provides an improved scheme taking slow wire feeding processing as a core, and aims to fundamentally solve the efficiency, cost and quality bottlenecks in the manufacturing process of high-precision internal gears. Disclosure of Invention The invention aims to provide a method for improving machining precision of an internal gear. The technical problems of low manufacturing efficiency, high cost and poor quality of the high-precision internal gear are solved. The technical scheme includes that the method for improving machining precision of the internal gear comprises the following steps of S1, preparing materials, S2, rough machining, S3, heat treatment, S4, semi-finishing of a tooth blank, S5, rough tooth shaping of the tooth blank, S6, surface hardening, S7, finishing of the tooth blank, S8, slow wire feeding, S9, polishing and deburring, and S10, and fluid polishing. In the method for improving the machining precision of the internal gear, the S1 material preparation is specifically that CF170 precipitation hardening stainless steel is selected as a material, and a forging or a precision casting is selected. In the method for improving the machining precision of the internal gear, the step S2 of rough machining is specifically that the method for ensuring the uniform allowance of all the shapes and the inner hole allowance is adopted to ensure that the basic shape and the size of the tooth blank are stable, so that the hole size and the final size of the tooth blank after rough machining are controlled to be 1mm. In the method for improving the machining precision of the internal gear, the S3 heat treatment specifically comprises the steps of treating the CF170 stainless steel tooth blank by adopting a solid solution, aging and cold treatment mode, wherein the control process of each link is as follows: Solution treatment of The temperature is 980-1050 ℃, the heat preservation time is 3-9 h, and the cooling speed is 20-50 ℃ per second by air cooling or oil cooling; Aging The temperature window is 440-540 ℃, the retained austenite is controlled to be 5-15%, and the heat preservation time is 2-4 hours; cold treatment In a liquid nitrogen medium, the constant temperature is 80 ℃ to 100 ℃ for 1 to 2 hours. In the foregoing method for improving machining precision of an internal gear, the step S4 of semi-finishing the tooth blank specifically includes the following steps: S401, releasing and removing residual stress, namely reducing the residual stress in the tooth blank through vibration aging or heat treatment aging treatment; s402, removing the redundant size of the tooth blank, namely removing the redundant allowance after heat treatment through a milling process and a turning process, ensuring that the size of the tooth blank is close to a final design value, and reserving the allowance on a single side by 0.5-1 mm; S403, improving the surface roughness or oxidation problem, namely adopting sand blasting, acid washing or polishing technology to reduce the surface roughness from Ra6.3μm to Ra3.2μm and thoroughly removing oxide skin; S404, removing the hardening layer and the oxide layer, namely removing the surface hardening layer by cutting; s405, controlling machining allowance, namely reducing the size tolerance of the tooth blank from +/-0.05 mm to +/-0.01 mm according to the tooth tip 0.8mm and the tooth root 0.5mm which are reserved allowance for the shape differentiation of the tooth blank; S406, improving the processing efficiency, namely reducing the semi-finishing time compared with the traditional method by adopting a high-speed milling and strong turning efficient process. In the method for improving the machining precision of the internal gear, the step S5 of the rough gear shaping machining of the gear blank specifically comprises the steps of adopting a numerical control gear shaping machine to machine the gear, and reducing machini