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As one of the most important types of energy, wind power generated electricity is used more and more commonly. For the system of wind power generated electricity, gear box is a key assembly and directly determines its performance. The surface accuracy of gears is one of the key factors which influence the gear box's property. Nowadays, blanks of wind power generating gears are often derived by hobbing and the finishing process is completed using the profile grinding method. In this process, extreme grinding points are very important for studying grinding process, optimizing grinding parameters and eliminating machining deficiencies. Therefore, a new method to determine extreme grinding points is proposed. Based on the meshing principle, surfaces of gear teeth are obtained. Using the profile grinding method, the model for determining extreme grinding points is developed and an iterative way is used to get the points. One example using typical wind power generating gears is carried out to illustrate the correctness and validity of the proposed method. more...

Due to properties of reducing impact，improving uneven load，and lowering noise in the meshing process，the technology of tooth surface modified are very common in the wind power gear. As the last process of machining gear，form grinding determines the accuracy of gear directly. Therefore，solving geometry error of form grinding becomes vital for optimize grinding tool path and enhancing the machining precision. Thus，this paper builds a model of geometrical error. In order to solve the geometry error of form grinding， firstly， tooth surface model of gears combining the profile and axial modification （including drum and helix modification） is constructed. Then，based on the tooth surface parameter，the length of common perpendicular between axes of the gear and the wheel，the contacting curve between the gear and the wheel is solved. The form grinding tooth surface is constructed. Finally，the geometrical error of tooth surfuce form grinding is defined by using the theoretical tooth surface and form grinding tooth surface， the geometric error model of tooth surface form grinding is established， some suggestions are given to reduce the geometry error of form grinding. more...

Abstract A successive tooth forming process for producing large modulus spur gears (m>2.5 mm) is firstly proposed in this paper to break the restrictions of large forming load and large equipment structure of traditional plastic forming. It contains the preforming stage and the finishing stage. In the first stage, the die with a single-tooth preforms gear teeth one by one through several passes. In the second stage, the other die with multi-teeth refines the preformed teeth into required shape. The influence of total pressing depth and feed distribution in preforming stage on final forming quality is analyzed by numerical simulation, and the reasonable process parameters are presented. Successive tooth forming experiments are carried out on the self-designed gear forming device to verify the optimal simulation results. Gears without fold defects are well formed both in simulations and experiments, proving the feasibility of this method. Compared with the whole die forging process, the new technology has advantages of smaller load and simpler tooling, which shows a good potential for manufacturing large modulus and large size spur gears. more...

Rack is the key component of the rotary device of the overweight roadheader. Its performance directly affects the bearing capacity, impact resistance and seismic resistance of the rotary device, which determines the safety, stability, reliability and service life of the roadheader. The deep carburizing and quenching technology, structure and distortion control technology of the 32 mm large modulus rotary rack in the rotary device of the roadheader are studied in combination with the performance requirements, structural characteristics and technical difficulties of heat treatment. The results show that, by the multi-stage carburizing process with high intensity carburizing and diffusion, the depth of the carburizing layer of the rack is up to 0.5 mm,the bending deformation of rack is 0.8~1.4 mm by process equipment and process control, and the metallographic structure are effectively controlled. more...

A successive tooth forming process for producing large modulus spur gears (m>2.5 mm) is firstly proposed in this paper to break the restrictions of large forming load and large equipment structure of traditional plastic forming. It contains the preforming stage and the finishing stage. In the first stage, the die with a single-tooth preforms gear teeth one by one through several passes. In the second stage, the other die with multi-teeth refines the preformed teeth into required shape. The influence of total pressing depth and feed distribution in preforming stage on final forming quality is analyzed by numerical simulation, and the reasonable process parameters are presented. Successive tooth forming experiments are carried out on the self-designed gear forming device to verify the optimal simulation results. Gears without fold defects are well formed both in simulations and experiments, proving the feasibility of this method. Compared with the whole die forging process, the new technology has advantages of smaller load and simpler tooling, which shows a good potential for manufacturing large modulus and large size spur gears. [ABSTRACT FROM AUTHOR] more...