Machining gearIt is an important part of modern mechanical transmission.From defense machinery to civilian machinery, from heavy industrial machinery to light industrial machinery, processing gear transmissions are widely used.With the rapid development of my country's industrial and agricultural production and science and technology, the demand for processed gears has increased significantly.Therefore, how to produce gears quickly, with high quality and precision has become an important link in the development of the machinery industry.In recent years, engaged inGear processingProduction workers, especially young workers, have made great progress.According to the characteristics of different gears, the distribution is slightly different.Automatic gearboxes are completely controlled by foreign companies and can only be equipped with gears.General gearboxes have a lot of foreign investment, and SEW of Germany is the main representative.Domestic enterprises are mainly famous enterprises.
Special gearboxes: State-owned enterprises occupy the main market.
High-speed and heavy-duty gears: mainly state-owned enterprises and foreign-funded enterprises.
Machining the gear base circle is the only parameter that determines the involute tooth profile.If there is an error in the base circle during gear hobbing, the tooth profile will inevitably have an error.The base radius R=hob moving speed/table rotation angular speed is the original tooth profile angle of the hob).In the hobbing process, the involute tooth profile is mainly ensured by maintaining a certain speed ratio between the hob and the gear blank.It can be seen that the tooth profile error is mainly determined by the tooth profile error of the hob, and the poor grinding quality of the hobbing edge is prone to tooth profile error.
With the continuous development of industrial technology, the requirements for the precision of machining gears are getting higher and higher.After arduous exploration, gear machinery has found that the reasons that affect the noise of processing gears are roughly as follows:
XNUMX. Ensure the quality of raw materials
The commonly used materials for making gears are alloy steels, such as 40Cr, 20CrMnTi, 40CrNi and 45 steel.In order to ensure the quality of raw materials, we adopt the method of fixed-point procurement, that is, we purchase high-quality steel produced by steel plants such as Shougang, Baosteel, Handan Iron and Steel. After arriving at the plant, they must undergo strict chemical composition inspection, particle size determination and purity evaluation, and the purpose is to facilitate timely adjustments. Heat treatment process, control heat treatment deformation, improve the quality of tooth profile processing.
XNUMX. Prevent heat treatment deformation
After rough machining or fine forging, the tooth blank must be normalized to eliminate internal residual stress; during normalizing or quenching and tempering, the furnace temperature must be kept uniform, and the work piece must be uniformly heated and cooled with the work station fixture; cyanidation should be used as much as possible The treatment is lower than carburizing and quenching temperature, less deformation, and cheaper than nitriding or carburizing.The equipment used for cyanide treatment must use a drip-type UNIC gas carburizing and nitriding furnace; some gear parts can also be changed to a soft nitriding process after high-frequency quenching and cyanidation treatment to obtain high hardness and thick white Bright layer.
Third, improve the precision of machining gears
1. Improve the machining accuracy of the gear hole: the dimensional accuracy of the gear hole must be distributed around the middle difference of the hole deviation value, generally set at 0.003 ~ 0.005 mm, if the deviation is within the range required by the hole design, it must be transferred to the gear cutting process Take measures; at the same time, the straightness of the hole must be controlled within 0.003 mm;
2. Control the end face runout and radial runout of the tooth blank: the end face runout of the tooth blank is an item that directly affects the tooth tolerance.When machining the two end faces of the tooth blank, ensure that the parallelism is within 0.01 mm, and then finish boring on the tooling to ensure the runout tolerance of the hole to the end face; when cutting the tooth, a 100% calibration circle is required to ensure the diameter of the ring gear Tolerance of runout.