Comparisons of Forging Ability between Electric Screw Press and Forging Hammer

The forging ability of a kind of equipment is mainly measured by its resistance to deformation and energy output. Although forging hammer and electric screw press are both forging equipment, it is difficult to determine how large the forging capacity of a screw press can correspond to the forging hammer. Because the forging hammer can withstand large deformation resistance, but the energy output is smaller each time. For the forgings with large deformation, it needs multi-hammer strike and energy superposition. The electric screw press can withstand less deformation resistance, but the output energy is large. For the forgings whose deformation resistance is within the forging capacity of the press, they are often forged at one time. I think we should compare the force-energy relationship between the two devices.

Forging hammer is a force-energy independent equipment. The impact force produced by forging hammer is calculated by momentum theorem. It is generally believed that the deformation resistance of forgings is related to the projection area, forging temperature and material quality of forgings. However, when the deformation resistance exceeds 1000 tons, forging cannot be carried out. When forging from raw billet to final forming, if the deformation work needed by forging is greater than the maximum strike energy of forging hammer, it is necessary to strike with multiple times and superimpose the energy until forming. The force-energy relationship is independent in forging process.

The screw press is an energy-limited equipment. The forging process is carried out in its closed body. The forging force is related to the total stiffness of the equipment, the energy of the moving part and the total mechanical efficiency. The force-energy relationship can be expressed by the following formulas:

F_max=

F_max is the biggest strike force.

E is the energy of the moving part.

C is the total stiffness of the machine.

Z is the total mechanical efficiency of machines.

 

Through the analysis of the force-energy relationship formula, it can be seen that for forgings with large deformation and small forming pressure, the press can give larger effective energy and smaller strike force, while for thin-walled parts with small deformation, such as blades, the press can produce larger strike force and give smaller energy. That is to say, the force-energy relationship of the press is not independent, but related. The national standard stipulates that under the condition of nominal strike force, the pressure can output more than or equal to 60% of the energy of the moving part.

Therefore, according to calculation and production practice, in the case of producing similar forgings economically, the forging capacity of 1T forging hammer is equivalent to about 400-500T of screw press. Of course, our electro-hydraulic hammer is more efficient.