Nowadays, the transmission of most cars has been gradually transferred from manual transmission to automatic transmission. Shaft and gear are the essential core parts of automatic transmission. No matter gear cutting, gear hobbing, gear hobbing, gear hobbing, gear hobbing, gear hobbing, gear hobbing, gear hobbing, gear hobbing, gear hobbing, etc. These play a key role in the production of automotive transmission.
Forging process
Forging blank is a process to obtain the blank of parts by forging method. Hot die forging is the most widely used blank forging process for automobile shaft and gear parts. Hot forging and cold extrusion are the most widely used forging methods in the past, but they are not particularly ideal in terms of precision and subsequent machining allowance. In recent years, cross wedge rolling technology has been widely used in shaft machining. This technology is especially suitable for the production of complex stepped shafts. It not only has high precision and small machining allowance, but also has better production efficiency than other methods.
Normalizing process
Normalizing, also known as normalizing, is the final temperature when the workpiece is heated until all free ferrite is transformed into austenite. Automobile shaft and gear parts must be normalized in order to obtain the hardness suitable for subsequent cutting and to prepare the microstructure for the final heat treatment so as to effectively reduce the heat treatment deformation. Due to the influence of operators, processing equipment and environment on non isothermal normalizing, it is difficult to accurately control the cooling rate and uniformity of workpiece. As a result, the hardness dispersion of the workpiece is large, and the metallographic structure is not uniform, which directly affects the metal machining and final heat treatment. The parts produced in this way often have large and irregular thermal deformation, the quality of the parts can not meet the requirements, and the loss of the cutting tool is also very large, especially in the process of rubbing teeth, which is under great stress. Therefore, it is necessary to adopt isothermal normalizing process. Practice has proved that isothermal normalizing can effectively improve the disadvantages of normal normalizing process, make the product quality more stable and reliable, and prolong the tool life.
Finish turning process
In order to meet the positioning requirements of high-precision gear processing, the finish turning of blank must be completed by CNC lathe. Take gear as an example, first finish turning of inner hole and locating end face, and then finish Finishing Machining of other end face and outer diameter simultaneously. This not only meets the requirements of perpendicularity between the inner hole and the locating end face, but also reduces the size dispersion of each gear in the production process of large batch of gear blanks, so as to improve the accuracy of gear blanks and ensure the machining quality of subsequent gears. Another advantage of choosing CNC lathe processing is to greatly improve the processing efficiency, reduce the number of equipment, save processing costs, and can bring better economic benefits.
Rubbing / hobbing / gear shaping
Gear hobbing machine and gear shaper machine are still widely used in gear processing. Although it is convenient to adjust and maintain, the production efficiency is low. If the production capacity is large, multiple machines need to be produced at the same time. With the development of coating technology, the second coating of hob and slotter after grinding can be carried out conveniently. The tool life can be significantly improved by coating, generally more than 90%. The tool changing times and grinding time are effectively reduced, and the benefit is remarkable.
Shaving
Radial shaving technology is widely used in the production of automobile gears with its advantages of high efficiency and easy realization of modification requirements of tooth profile and tooth direction. The influence of tooth profile and tooth direction on vehicle noise is great. The transmission noise of transmission can be reduced by modifying the profile and anti twisting. Wechat of metal processing has good content and deserves attention.
heat treatment
Automobile gears are required to be carburized and quenched to ensure the good mechanical properties required by the design. Stable and reliable heat treatment equipment is indispensable for the products that are not grinded after heat treatment.
Grinding
The essence of metal grinding is that the metal surface of the workpiece is grinded, which is extruded by innumerable abrasive particles instantaneously and produces deformation under the action of friction, and then turns into wear debris and forms a smooth representation process. It is mainly used for the gear bore after heat treatment. Finish machining of the end face and the outer diameter of the shaft to improve the dimensional accuracy and shape and position accuracy. The pitch circle fixture is used for positioning and clamping of gear processing, which can effectively ensure the cnc machining accuracy of tooth and installation reference, and obtain satisfactory product quality. The grinding accuracy usually reaches the tolerance level of it6-it7, and the surface roughness reaches ra1.25-0.16um.
Retouching
This is to check and clean the bumping burr of the gear before assembly, so as to eliminate the abnormal noise caused by them after assembly. This is accomplished by listening to the sound of a single pair of meshing or observing the meshing deviation on a comprehensive tester. It is also used to check the burr, center distance and runout with automatic meshing instrument.
