A machining method of a thin-walled long cylinder gear with inner and outer teeth

Abstract

The present application belongs to the field of mechanical processing and relates to a processing method of a long-thin-wall gear ring with inner and outer teeth, which optimizes the whole processing procedure of the part: forging, isothermal normalizing, rough machining, quenching and tempering, stress relieving annealing, semi-finishing, stress relieving annealing, finishing, tooth making (hobbing + gear shaping), deburring, nitriding treatment, stress relieving annealing (aging treatment twice), finishing and finished product. The increased stress relieving annealing has low cost, but can significantly reduce the deformation in the processing of the part, which can significantly improve the precision and qualification rate of the part. It is beneficial to the stable batch production of the product and can reduce the overall production cost and cycle to a certain extent.

Description

Technical Field

[0001] This invention belongs to the field of machining and relates to a machining method for a thin-walled long cylindrical gear ring with internal and external teeth. Background Technology

[0002] For thin-walled long cylindrical gear rings with internal and external teeth, the thickness of the gear ring wall is very thin, with the thinnest gear ring wall being only about 2mm, but the diameter is 100mm and the axial dimension is nearly 50mm. It belongs to the thin-walled long cylindrical structure, and the precision machining and heat treatment deformation control are particularly complex.

[0003] Current processing methods include: one is to first perform fine machining on the gear blank, then perform gear machining, and finally perform final heat treatment such as nitriding to finish the product. The process flow is: bar stock—rough machining—quenching and tempering—semi-finishing—finishing—gear making (gear hobbing + gear shaping, burnishing)—deburring—nitriding treatment—finished product. Gear machining includes gear hobbing, gear shaping, burnishing, and other methods for gear finishing.

[0004] However, because this processing method involves precision machining and heat treatment on a precision gear blank, due to the large size and thin walls of the parts, there are significant deformation problems in both gear machining and final nitriding heat treatment, which seriously affect the machining accuracy and pass rate of the gear ring, especially for parts with thinner walls, longer barrels, and higher precision. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a processing method for a thin-walled long cylindrical gear ring including internal and external teeth, which optimizes the entire processing flow of the part, optimizes and adjusts the gear blank in order to reduce the deformation during the gear making and nitriding process, and adds a stress relief process to ensure dimensional stability.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for processing a thin-walled long cylindrical gear ring including internal and external teeth, comprising the following steps:

[0007] A. Provides gear forgings, rough-machined forgings, and removal of a large amount of excess material;

[0008] B. Normalizing treatment: The forging is treated with isothermal normalizing process. After the treatment, it is subjected to rough machining, tempering and quenching process, and stress-relieving annealing process.

[0009] C. The blank is semi-finished, then stress-relief annealing is performed, followed by grinding. The blank is then machined by turning with a lathe, hobbing with a hob, and shaping with a cutter. After deburring, it is nitrided.

[0010] D. After nitriding, a stress-relieving annealing process is performed again. The inner hole, end face, and outer diameter of the shaft of the heat-treated gear are then precision machined. After completion, the finished product is inspected.

[0011] Optionally, the inner and outer surfaces of the teeth are thickened to increase rigidity, ensuring that the thinnest wall thickness during heat treatment and gear shaping is not less than 1 / 10 of the radius and 1 / 5 of the axial dimension; the thickened part is then removed by finishing after nitriding-stress relief annealing.

[0012] Optionally, in step D, the stress-relief annealing process involves aging treatment twice.

[0013] The beneficial effects of this invention are as follows: The increased cost of multiple stress-relief annealing processes is not high, but it significantly reduces deformation during part processing, which significantly improves part accuracy and yield. The increased local wall thickness during processing enhances part rigidity and reduces cold and hot working deformation, further improving part accuracy and yield. This facilitates stable mass production and reduces overall production costs and cycle time.

[0014] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Detailed Implementation

[0015] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0016] A processing method for thin-walled long cylindrical gear rings with internal and external teeth is provided for thin-walled long cylindrical gear rings with internal and external teeth, where deformation is difficult to control due to the thinness of the gear ring wall, and in combination with the purpose of the final heat treatment: nitriding aims to increase the strength and durability of the tooth surface.

[0017] Optimize the entire machining process of the part, including the following steps:

[0018] A. Provides gear forgings, rough-machined forgings, and removal of a large amount of excess material;

[0019] B. Normalizing treatment: The forging is treated with isothermal normalizing process. After the treatment, it is subjected to rough machining, tempering and quenching process, and stress-relieving annealing process.

[0020] C. The blank is semi-finished, then stress-relief annealing is performed, followed by grinding. The blank is then machined by turning with a lathe, hobbing with a hob, and shaping with a cutter. After deburring, it is nitrided.

[0021] D. After nitriding, stress-relieving annealing (aging treatment twice) is performed again. The inner hole, end face, and outer diameter of the shaft of the heat-treated gear are then precision machined. After completion, the finished product is inspected.

[0022] Meanwhile, in order to reduce the deformation during the tooth making and nitriding process, the tooth blank is optimized and adjusted, and the inner and outer parts of the tooth are thickened to increase rigidity. This ensures that the thinnest wall thickness during heat treatment and tooth shaping is not less than 1 / 10 of the radius and 1 / 5 of the axial dimension. The thickened part is then removed by finishing after nitriding and stress-relief annealing.

[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for machining a thin-walled long cylindrical gear ring including internal and external teeth, characterized in that, Includes the following steps: A. Provides gear forgings, rough-machined forgings, and removal of a large amount of excess material; B. Normalizing treatment: The forging is treated with isothermal normalizing process. After the treatment, it is subjected to rough machining, tempering and quenching process, and stress-relieving annealing process. C. The blank is semi-finished, then stress-relief annealing is performed, followed by grinding. The blank is then machined by turning with a lathe, hobbing with a hob, and shaping with a cutter. After deburring, it is nitrided. D. After nitriding, a stress-relief annealing process is performed again. The inner hole, end face, and outer diameter of the shaft of the heat-treated gear are then precision machined. After completion, the finished product is inspected. The stress-relief annealing process involves aging treatment twice. The inner and outer surfaces of the teeth are thickened to increase rigidity, ensuring that the thinnest wall thickness during heat treatment and gear shaping is not less than 1 / 10 of the radius and 1 / 5 of the axial dimension; the thickened part is then removed by finishing after nitriding and stress-relief annealing.