In many different industries, gear transmission is a common way to transmit power. Soft tooth surface gears have gradually been phased out in favor of hard tooth surface gears that have been carburized and hardened as a result of advancements in processing technology. It increases the contact and bending strength of the teeth as well as torque transmission in a smaller volume. Click here for Grinding and Polishing Wheels.
The term "hard-toothed gears" describes gears that are harder than HRC40. Quenching or carburizing and quenching typically require heat treatment. The workpiece will be deformed after heat treatment, and the precision of its pre-heating processing will typically be reduced by 1-2 grades. As a result, after heating, finishing is required. For such high-precision hardened gears, the most common processing method is to hob first, then carburize and quench, and finally grind the tooth surface. The entire tooth surface can be given the same structure and carburized layer as a result of this process. Depth, the final hardness of the tooth surface can reach HRC58-HRC62, and the tooth surface can have high geometric accuracy and surface finish.
Integral hobs are used to process smaller modulus workpieces, and the material is typically coated with high-speed steel or powder metallurgy. It is generally designed as an insert hob due to the large size of the hob body and the high cost of gear with a large modulus. Such hobs must check the wear of each blade regularly and replace any worn or chipped blades. Drop: Gear milling cutters are commonly used for processing extra large modulus gears (generally M>22).
Gear grinding is the most effective and dependable method for achieving high precision of the tooth surface, as well as grinding off the hobbing allowance and its deformation. The gear will be corrected to some extent on the standard involute tooth shape and tooth direction to make the force and meshing of the gear more reasonable under load. Through preset parameters, the CNC gear grinding machine grinds the tooth shape to the required geometric accuracy. The final roughness requirement can be met by selecting the appropriate grinding wheel and dressing parameters. The industry standard is Ra0.8, but there are some special applications, such as wind power gearboxes, that require Ra0.6 or even higher. Its processing methods are divided into two categories: developing grinding and forming grinding.
The processing of the generating method is similar to the hobbing principle. Because the grinding wheel continuously meshes with the tooth to be ground during the grinding process, the involute shape of the tooth is developed, and there is no interruption in the grinding process, its processing efficiency is very high. Because of the size of the grinding wheel, generating grinding is best suited for processing smaller modulus gears (generally M=12).
During the grinding process, an alumina grinding wheel can be used, and it must be processed by the set wear life length and serial hob shifting method. The hob is shifted step by step during the hob shifting process to achieve the highest material removal efficiency; during the fine grinding process, the hob is shifted at the same position while the grinding wheel is ground to maintain the stability of the tooth surface quality. High-precision CBN worm grinding wheels are another option for the mass production of a single variety of gears. These wheels can significantly increase grinding efficiency but are relatively expensive.
The grinding wheel is cut to match the diamond wheel's tooth shape, and each tooth is ground. This manufacturing process is fairly adaptable. Only the grinding wheel needs to be cut to the proper shape when the gear model is changed. Preset CNC axes manage the entire dressing and machining process.