Curved cylindrical gear is a new type of parallel shaft transmission gear, whose teeth are circular arc. In the course of meshing, gears are divided into point contact curve cylindrical gears and line contact curve cylindrical gears according to different contact forms of tooth surfaces.
At present, the transmission performance of line contact curve cylindrical gear has been widely studied by scholars at home and abroad, but no efficient processing method has been found. Although many scholars have been constantly exploring the feasibility and efficiency of various processing methods, they have not achieved good results. Song Aiping proposed a parallel link type machining mechanism to machine this kind of curved cylindrical gear, but the mechanism has low stiffness, can not machine materials with high hardness, and has low machining efficiency. Tang Rui and others designed a special machining machine tool based on single edge milling cutter. FUENTES et al. proposed to use a double edge milling cutter to process one of the gears, and a single edge milling cutter to process the concave and convex tooth surfaces of the other gear. The nominal diameter of the single edge milling cutter is slightly larger than that of the double edge milling cutter. The specific size needs to be determined through complex theoretical calculations. This method requires 3 different cutters, and the nominal diameter of the single blade cutter head needs to be adjusted, so the processing technology is complex. UZUN and INAN used ball end milling cutter to process line contact gear on vertical CNC milling machine, but this processing method is extremely inefficient, and the tooth surface finish is difficult to meet the requirements. SUN, ZHANG and others put forward a planetary gear system for processing line contact gears. This structure has a limited number of installed cutter heads and low processing efficiency.
A processing method of line contact curve cylindrical gear is proposed. Based on the meshing theory, the mathematical model of line contact curve cylindrical gear is derived, and the three-dimensional model of the gear is built. The deviation between the three-dimensional model and the processed curve cylindrical gear is compared and analyzed:
(1) Two different single edge milling cutter heads are installed on the existing six axis CNC gear milling machine to process linear contact curve cylindrical gears, which has lower cost and higher efficiency. But compared with the point contact curve cylindrical gear machined with a double edge milling cutter, its machining efficiency is lower;
(2) Through deviation comparison, the maximum deviation of the machined curved cylindrical gear tooth surface is 0. 06 mm, but this part of deviation includes the deviation of three-dimensional modeling of curved cylindrical gear, and the actual deviation may be far less than this value; On the whole, it is feasible to adopt the method proposed in the paper;
(3) The processing scheme proposed in this paper can reduce the investment of scientific researchers in the research of special line contact curve cylindrical gear machine tools, and provide a reference for the industrial batch production of line contact curve cylindrical gears.
This paper presents a method of machining spiral bevel gears without special machine tools and special cutters. The existing single edge milling disc cutter and six axis CNC gear milling machine are used to machine line contact curve cylindrical gears. Based on the meshing theory, the tooth surface equation is derived, and the three-dimensional model of the gear is established; VERICUT software is used to verify the feasibility of the proposed processing method.