NC machining technology of spiral bevel gear

The processing technology of spiral bevel gear is to first cut the gear surface, then select some reference points on the gear surface as the benchmark, and use the continuous tangent principle to calculate the parameters such as the position, normal vector and normal curvature of the reference point, and then calculate the normal curvature according to the requirements of contact conditions to determine the adjustment parameters of small gear cutting. However, this machining method based on the local conjugate principle has low efficiency and difficult to ensure the accuracy. After independent experimental calculation, American scholars put forward the local synthesis method of gear NC machining process. Through process improvement, the machining defects caused by the inability of conjugate principle to pre control the second-order contact parameters are avoided. The improved process first cuts the large gear tooth surface, selects the reference point as the reference, and then pre controls the second-order contact condition parameters at the reference point to calculate the principal curvature and principal direction of the small gear tooth surface at the reference point, which improves the machining process of spiral bevel gear.

spiral bevel gear

According to the theory of spiral bevel gear, the conjugate surface of line contact or point contact is obtained by using the auxiliary surface. Using this principle, the envelope surface of conjugate tooth surface can be solved quickly, so that the machining quality of spiral bevel gear is easy to control and the accuracy is higher. With the further research of spiral bevel gear machining theory, scholars use the theory of spiral bevel gear meshing analysis principle to analyze the NC machining technology of spiral bevel gear. Because the tooth surface of spiral bevel gear is a complex curved surface, it is required to produce complex spiral cutting motion between tool and parts during machining. In terms of gear transmission, bevel gear is used to transmit the motion and power between intersecting shafts, quasi biaxial gear transmission is used to transmit the motion and power between staggered shafts, and quasi hyperbolic gear transmission is mostly used for the deceleration motion of the rear axle of automobile and construction machinery. Although China’s modern spiral bevel gear technology started later than western developed countries, great progress has been made through the introduction of advanced technology. Spiral bevel gear has the advantages of large bearing capacity, large transmission overlap coefficient and long service life. The model diagram of spiral bevel gear is shown in the figure.

With the advantages of low cost, short cycle and high precision, the application technology of NC machining and cutting spiral bevel gear tooth surface has obtained high meshing accuracy and good tooth surface roughness quality. During the NC machining of spiral bevel gears, the tool path in the machining process of large and small gears of long cone pitch spiral bevel gears is calculated, the corresponding NC machining program file is generated, and then the tooth cutting is completed on the four-axis linkage NC gear milling machine, which gets rid of the limitations of traditional machine tools in machining long cone pitch spiral bevel gears. NC machining technology combines with virtual simulation technology to simplify the machining process and improve the machining efficiency. At present, the NC machining process of spiral bevel gear has begun to effectively integrate the tooth surface milling control technology and intelligent manufacturing technology, so as to continuously improve the quality and accuracy of spiral bevel gear.

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