Analysis and solution of the fracture of the tie rod of Standard Injection Molding Machine

Analysis and solution of the fracture of the tie rod of Standard Injection Molding Machine



1. Analysis of the reason for the breakage of the tie rod of the Standard Injection Molding Machine
Fatigue damage. The working process of the machine is a process of exchanging stress, so any factor that causes stress concentration will cause fatigue damage.
E.g:
1. On stairs where the shaft diameter varies greatly.
2. Insufficient corners, undercuts, etc. during conversion.
3. Surface wounds or machining screws accidentally damage the surface of the optical axis.
4. The surface roughness of the thread is too large.
5. The screw is under long-term pressure and the surface strength is insufficient, resulting in surface extrusion damage (modeling nut).
Improper heat treatment of the screw surface causes stress concentration.

Material defects, overload tensile fracture:
The toggle lever obtains the clamping force through the deformation of the four levers. Therefore, if the length of the four levers is different, the deformation will be different. For example, if one of the four is short, the short lever may far exceed the 1/4 clamping force it needs to withstand, resulting in tension fracture.

Pulling due to temperature deformation:
If the four levers are of different lengths (for example, one length and three short), the long lever will be constrained by the other three levers due to the sharp or decrease in temperature. When it becomes static, the lever may break.
Tensile force caused by compound deformation:
When the mold is uneven, the overall error of the connecting rod (hinge) length, the height of the bearing base, the lever length and other parts is too large, resulting in uneven force on both sides when the connecting rod is straightened.

E.g:
1. The back template swings, the lever is bent, and the lever is easily pulled under the action of bending stress and tensile stress.
2. Due to the flash of the product, usually inexperienced workers will further increase the clamping force, causing the lever to be overloaded and the mold to be overloaded and deformed.
Damage caused by instant impact stress:
Because the clamping force can be released before the toggle lever is opened,

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