Analysis of NC machining process of spiral bevel gear

1. NC machining process principle of spiral bevel gear

Spiral bevel gear is only a kind of gear transmission, and the machining method is more complex. Spiral bevel gear is mainly used in the transmission process of automobile differential. The consumption of spiral bevel gear and hypoid gear is very large, which requires both high productivity and high precision. The longitudinal tooth line of spiral bevel gear is circular arc, and the tooth height shrinks from the big end to the small end. Using this method to process spiral bevel gear, the machining technology of hypoid gear is realized. Spiral bevel gear has complex tooth surface geometry. When using 3D modeling software to model it, the amount of calculation is large, and the simulation process is more difficult. Therefore, according to the process characteristics of spiral bevel gear NC machining, scholars use vector analysis method and velocity derivation method to simulate the NC machining process of spiral bevel gear, and then use computer to simulate the specific NC machining process of spiral bevel gear.

2. NC machining process of spiral bevel gear

Choosing reasonable cutting speed and feed speed can prolong the service life of the tool, which is the key to the realization of the scraping process of spiral bevel gear on NC machine tools. When NC machine tool scrapes the surface of spiral bevel gear, it is very important to select the appropriate cutting speed. It determines the service life of the cutter and the surface roughness of the spiral bevel gear. If the cutting speed is too high, the cemented carbide blade will be fatigued; If the cutting speed is too low, the comb crack on the cemented carbide blade will increase, and the crack on the blade surface will continue to expand to form tool collapse. During actual machining, the hard scraping speed should be slightly lower than the soft scraping speed. At the same time, according to the characteristics of large volume and high hardness workpiece, the cutting tool with large gear ring (20 m · min-1) and small gear ring (50 m · min-1) should be selected to have the best effect. NC machining scraping is to scrape the tooth surface of large gear first, and then scrape the small tooth surface for correction. During scraping, divide the feed into 3 or more times, and assist in the use of rotary distributor. In addition, the engineer studied the parametric modeling of cutter head entity and gear blank entity, proposed the calculation method and formula of three-dimensional solid modeling, parameterized all the process of scraping tooth surface, and improved the stability and accuracy of machining. When NC machining scraping pinion, use single-sided internal and external precision cutting tools to process the convex and concave surfaces of the gear, as well as the length and position of the gear, and constantly correct and modify the machining parameters.

3. Practical application of NC machining process of spiral bevel gear

Spiral bevel gear has strong bearing capacity, stable transmission and high tooth surface overlap coefficient, so its machining process must comprehensively consider many factors such as material, machining accuracy and machining environment. In case of machining deviation, the normal surface parameters of cycloid tooth profile shall be modified in time to avoid affecting the accuracy of tooth profile due to machining process error. At the same time, there is machining deformation in NC machining tools and workpieces. The key to high-precision machining of spiral bevel gears is to establish a reasonable tool path and adopt the optimal algorithm to reduce machining deformation. At present, engineering universities mostly use the five axis NC machining technology of spiral bevel gear to reduce the tooth surface deformation of spiral bevel gear. When the gear is actually machined, the engineer will also use UG modeling software to model the spatial entity of spiral bevel gear to determine the machining parameters and path. Especially when machining the tooth profile of spiral bevel gear, it is necessary to establish a finite element model for side milling to analyze the causes of machining thermal deformation of the tooth profile and reduce the deformation of the tool and the deformation error between the tooth surface and the tool in the process of side milling.

Scroll to Top