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Different Process Methods for Precision Die Forging

There are many precision die forging processes that have been used in production. According to the different forming temperature, it can be divided into hot precision forging, cold precision forging, warm precision forging, compound precision forging, isothermal precision forging and so on.

Ⅰ. The hot precision forging process among the precision die forging processes

1. The precision die forging process whose forging temperature is above the recrystallization temperature is called hot precision forging. The hot precision forging material has low deformation resistance and good plasticity, and is easy to form more complex workpieces. However, due to strong oxidation, the surface quality and dimensional accuracy of the workpiece are low.

2. The commonly used forging process method of hot precision forging is closed die forging process. Due to inaccurate blanking, insufficient die design and manufacturing accuracy, the closed die forging process has a large deformation resistance in the final clamping stage, which will cause great damage to equipment and dies. The commonly used method to solve this problem is the principle of shunting and depressurization, that is, a shunt and depressurizing cavity with reasonable shape and size is set at the place where the closed cavity is filled at the end. When the cavity is completely filled, the excess metal of the blank is extruded from the split cavity hole, which not only solves the contradiction that the blank volume and the cavity volume cannot be strictly equal, but also reduces the internal pressure of the cavity, which is beneficial to improve the service life of the die.

3. The development of hot forging process has been very mature, the economic benefits are obvious, and it has been widely used, especially in the gear forging industry.

Ⅱ. Equipments suitable for hot precision forging process

1. There are many types of equipment used in the hot precision forging process, mainly including CNC die forging hammers, screw presses, hot die forging presses and so on.

2. The CNC die forging hammer has a fast striking speed, which enables the red hot metal forging material to be quickly formed in a short time, thereby improving the flow effect of the metal, and also greatly reducing the stamping on the die. The striking energy can be precisely controlled. In addition to improving the forging efficiency, it also reduces the die loss. Therefore, the CNC hydraulic die forging hammer is an ideal equipment for the closed die forging process.

3. Screw presses suitable for hot precision forging process are divided into friction presses and electric screw presses according to different power transmission methods. As the name implies, the friction press transfers the kinetic energy generated by the motor to the screw through friction, and then realizes the rise and blow of the slider. The electric screw press directly transmits the kinetic energy of the motor to the screw through gear transmission, which greatly reduces the loss of forging materials during the energy transmission process, and also reduces the noise during the operation of the equipment, and can be controlled by PLC to achieve the recycling of inertial energy. While saving energy, it can also achieve precise control of energy.

4. Compared with other types of presses, the electric screw press has the advantages of fast forging speed, simple principle and low maintenance cost. Therefore, the electric screw press is an upgraded product of the friction press. Compared with the forging hammer, the vibration is low and the noise is low. Both are suitable for small batch and multi-variety production. The replacement of dies of precision die forging is convenient and simple, and the organization of production is more flexible.

5. The working principle of the hot die forging press is that the motor drives the crankshaft, and the crankshaft drives the slider through the connecting rod to move up and down to achieve the effect of forging precision die forging materials. Since the hot die forging press has a bottom dead center, the size of the metal forging tools produced is consistent. However, if the required deformation force of the forging exceeds the capacity of the press, the press will be stuck before passing the bottom dead center, commonly known as stuffed lathe, the power part of the press has to be disassembled and reassembled to restore the operation of the equipment. Therefore, compared with forging hammers and screw presses, hot die forging presses have the advantages of good uniformity of the forgings produced, but they also have the disadvantages of high cost and complicated replacement of dies of precision die forging. This precision die forging equipment is suitable for large batch and small-variety production of forgings.