In the production and application process, pultrusion mold may fail often in various different situations, which will waste a lot of labor costs, material resources, and affect the production schedule. Several of the main mold basic failure modes and failure reasons and preventive measures.
The pultrusion mold failure
The basic form of hot and cold mold failure in service can be divided into plastic deformation wear, fatigue, and fracture.
(1) The plastic deformation.
Plastic deformation under load is greater than the yield strength and deformation generated. Such as the die cavity collapse hole appears, expand, edges and corners collapse depression and punch appeared upsetting longitudinal bending. Especially hot work die, its work surface and high-temperature materials contact, the surface temperature of the cavity is often more than hot work die steel tempering temperature, type of groove of the inner wall due to softening and collapsed under or heap.
(2) Wear failure.
Wear failure refers to the edge, the edges and corners rounded door passivation, plane surface subsidence, grooves, spalling mucosa (sheet mold in the friction and stick some blank metal).
(3) The fatigue failure.
Features: certain parts of fatigue failure of the die after a certain period of service, the initiation of small cracks, and gradually to expand in-depth, expanded to a certain size, severely weakened the bearing capacity of the die and cause a fracture. Fatigue crack adorable was born in stress large parts, especially the stress concentration position (size of the transition, the gap, knife, wear cracks), fatigue fracture when the door is divided into two parts, one part for fatigue at fatigue crack development and the formation of the broken section, showing the conchoidal, fatigue source is located in the shell vertex. Another part is the sudden fracture appears uneven, rough section. To mold the fundamental cause of fatigue damage for ring load, all can make the surface tensile stress increase factors that can accelerate the fatigue crack initiation.
(4) Failure.
Fracture failure of common forms: chipping, Luo teeth, splitting, broken, cracking, the driving force of mold fracture is different in different.
Mould fracture process is of two kinds: disposable fracture and fatigue fracture. The disposable fault is sometimes in the stamping die suddenly fracture, crack initiation after once, instability, expansion. The main reasons for it is the serious overload or die materials serious embrittlement (such as overheating, insufficient tempering, severe stress in ten and serious metallurgical defects, etc.).
