How to control the deformation of precision gear stamping
- The main factors affecting the heat treatment deformation of gears
1. The influence of material metallurgical factors on gear deformation: the higher the hardenability of steel, the greater the deformation. When the center hardness is greater than 40HRC, the amount of deformation increases significantly. Deformation is more stable, provided by steel mills, deformation is low, stable, steel. When the content of a/n is controlled between 1 and 2.5, the hardenability zone can be reduced and the amount of deformation can be reduced.
2. The effect of preliminary heat treatment on gear deformation: the normalizing hardness is too high, and a large amount of sorbite will increase the deformation of the inner hole, so the forgings should be treated with temperature-controlled normalizing or isothermal annealing.
3. Influence of carburizing process on deformation: uniformity of temperature. The uniformity of the carbon layer and the uniform temperature of the cooling system medium will affect the analysis of the deformation of the gear structure. At the same time, the carburizing temperature is required to be higher and higher, the thicker the carburized layer, the lower the oil temperature, and the larger the gear deformation.
4. Influence of quenching on deformation: Quenching and cooling behavior is an important factor affecting the deformation of gears, and the deformation of hot oil quenching is smaller than that of cold oil quenching. The cooling ability of the oil is also key to deformation. The mixing mode and strength are affected by deformation, quenching pressure quenching plate gears, according to the deformation of various gears. By adjusting the parameters of the punching machine, reducing the deformation, adjusting the pressure of the inner and outer die and the expansion pellet, adjusting the size of the oil injection of each section and the size of the top table, the deformation is controlled.
5. Clamping method and fixture: The purpose is to make the workpiece heat and cool evenly, and the carburized layer of each part of the workpiece is uniform to reduce uneven thermal stress and structural stress, thereby reducing deformation. The clamping mode can be changed. The disc part is perpendicular to the oil surface, and the shaft part is installed vertically, using compensation washers, support washers and superimposed washers. The splined hole parts can be carburized mandrels.
There are many factors that affect the deformation of carburizing heat treatment, which may be the result of the comprehensive influence of various reasons. Only by controlling various factors, the deformation can be controlled to a lesser extent. Controlling gear deformation is also an important problem to be solved in the whole process of gear manufacturing.
2. Specific control measures for gear heat treatment deformation
Through the above analysis, it is known that there are many factors that affect the deformation of gears during heat treatment, and they exist in each link. In order to control the deformation of gears during heat treatment, relevant technical personnel can refer to specific control measures to improve the quality of gears.
1. Scientific selection of gear material
The hardenability of gear raw materials directly affects the heat treatment deformation of gears. It is necessary to scientifically select the raw materials for making gears. Different materials have different hardenability. , Compared with other materials, the hardenability of steel is better. At the same time, the precision of the gear will also affect the hardenability of the raw material. For example, the raw material of the gear in my country is mainly 20Cr Mn Ti steel. This kind of steel has uneven crystals and is prone to heat treatment deformation. In addition, considering the overall cost, it is necessary to choose suitable machining equipment.
2. Reasonable gear design
Relevant designers should fully consider the various reasons that cause the deformation of the gear heat treatment process, and design the gear shape scientifically and rationally without changing the original performance. Simple and direct is the best, so as to reduce the deformation problem caused by uneven force.
3. Select the appropriate heat treatment process
In the process of heat treatment of gears, quenching oil should be selected as the quenching medium. Hot oil quenching has smaller deformation than cold oil quenching. The cooling capacity and stirring method of the oil are also important factors affecting the deformation. At the same time, additives should be properly applied to improve the hardness of gear parts. , to ensure the quality of the gear.
4. Optimize the charging method
In order to make the gear parts heat evenly during the heating process, the charging method can be optimized. The disc parts are placed vertically with the oil surface, and the shaft parts are installed vertically. At the same time, compensation washers can be used to reduce gears caused by uneven heat. Deformation occurs.
After the gear is forged, there will also be uneven heating in the heat treatment process due to uncontrollable stress. Preheating can effectively prevent this from happening. Preheating after forging can improve the quality of gear raw materials. The organizational structure can effectively prevent the problem of deformation due to stress redistribution.
6. Improve the quality of machining
In the selection of mechanical equipment, it is necessary to choose high-quality mechanical equipment. Considering a series of factors that affect the deformation of the gear heat treatment, the technicians can summarize the reasons for the deformation of the gear, and prepare a preventive plan in advance in the subsequent heat treatment process of the gear, which can effectively prevent the occurrence of deformation. In addition, for gears with special materials and strange shapes, secondary heat treatment is required to be safe.
From the above analysis, it is known that there are many factors that affect the deformation of gear heat treatment. In order to
It can effectively prevent the occurrence of gear heat treatment deformation, not only to scientifically select the material of cast gears and reasonable gear design, but also to make full use of thermal processing technology to comprehensively improve the quality of machining, thereby effectively reducing the probability of gear heat treatment deformation. , to ensure the service life of the gear.