Gear heat treatment
The heat treatment deformation of carburized gear directly affects the accuracy, strength, noise and life of the gear. Even if the gear grinding process is added after the carburizing heat treatment, the deformation still reduces the gear accuracy level. There are many factors that affect the deformation of carburizing heat treatment, and only by controlling various factors can the deformation be controlled to a small extent. Controlling gear deformation must also be solved in the whole process of manufacturing gears.
Influences
(1) The influence of gear material metallurgical factors on deformation
Tests show that the higher the hardenability of steel. The greater the deformation. When the core hardness is higher than 40HRC, the deformation will increase significantly. Therefore, there are certain requirements for the hardenability of steel, the narrower the hardenability band. The more stable the deformation, the steel mill is required to provide "low and stable deformation" steel. The A1/N content ratio is controlled within the range of 1 to 2.5, which can narrow the hardenability band and reduce deformation. In addition, the box segregation and band structure of the material affect the uneven deformation and uneven carburization of the gear spline hole.
(2) The influence of preliminary heat treatment on gear deformation
Excessive normalizing hardness, mixed crystals, a large amount of sorbite, or Widmanstatten structure will increase the deformation of the inner hole, so temperature control normalizing or isothermal annealing should be used to treat forgings.
(3) The influence of the carburizing process on deformation
Uniformity of temperature. The uniformity of the carbon layer and the uniformity of the cooling medium temperature affect the deformation of the gear. At the same time, the higher the carburizing temperature, the thicker the carburizing layer. Low oil temperature and large gear deformation. Therefore, it is necessary to improve equipment, optimize technology, and improve the quality of gear heat treatment.
(4) The effect of quenching on deformation
Quenching cooling behavior is the most important factor affecting gear deformation. Hot oil quenching has less deformation than cold oil quenching and is generally controlled at 100℃±120℃. The cooling capacity of the oil is also critical to deformation. The stirring method and intensity affect the deformation, and the disk gears quenched by the upper quenching press are subject to the deformation of various gears. Adjust the parameters of the flushing press to reduce the deformation, adjust the pressure of the inner and outer die and the expansion block, the size of each section of the fuel injection, and the upper work table to control the deformation.
Clamping method and fixture
The purpose is to make the workpiece heating and cooling uniform, the carburized layer of each part of the workpiece is uniform, so as to reduce the uneven thermal stress and the uneven structural stress, to reduce deformation, and the clamping method can be changed. The disc parts are perpendicular to the oil surface, and the shaft parts stand upright. Install, use compensation washer, support washer, superimposed washer, etc., spline hole parts can be carburized mandrel, etc.
Machining coordination
First, grasp the heat treatment deformation law, move the position of the tolerance zone, and improve the product qualification rate;
Second, according to the law of deformation, use anti-deformation and pre-expansion holes at the shrinking end to increase the qualified rate of deformation after quenching;
Third, the method of reserved machining amount is used for asymmetric or uneven thickness parts. Processing after heat treatment;
Fourth, after heat treatment, use a push knife to finish the spline hole, or electrolytically process the spline hole, or heat the mandrel after carburization for quenching, and then press out the mandrel to ensure the size of the spline hole to reduce deformation.
Luoyang Yujie Industry &Trade Co.Ltd located in Luoyang City, one of the main heavy industrial bases in China. We specialize in the production of bearings, nonstandard machinery parts, machine tools. For the bearings, we can offer cross roller bearing, slewing bearing, YRT bearing, thin section bearing, ball screw bearing, deep groove ball bearing, etc. For the nonstandard machine parts, we can produce gears, shafts, sprockets, molds, rollers, pulley, mining machine parts, etc as per customer drawing and requirements. For the machine tools, we offer CNC vertical machine center, CNC horizontal lathe, CNC gantry boring and milling machine, CNC floor type boring, and milling machine.
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Luoyang Yujie Industry & Trade Co., Ltd.
Tel: +86-379-80865527
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Email:sales@yujieindustry.com
ADD: Jianxi Industrial Park, Luoyang City, Henan, China
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