The failure of pipe fitting dies is divided into abnormal failure and normal failure. Abnormal failure is the failure of the mold to achieve normal use, maintenance of the service life.
The situation of early failure and abandonment; Normal failure means that the mold is used in mass production because of slow plastic deformation, uniform wear and tear, etc.
Failure to continue working.
The failure modes of the mold include:
1. Plastic deformation
The plastic deformation mainly consists of upsetting, bending, cavity deformation and collapse. Because the mold works with a greater stress, when the stress exceeds the mold.
When the yield limit of the material is limited, the plastic deformation will be produced and its geometric shape or size will be changed. The yield process of die material during plastic deformation.
It is usually carried out by lattice slip, twin crystal and grain boundary slip. Whether the mold produces plastic deformation and the working temperature of the stress and mold.
And the high temperature strength of mold materials.
2. Wear failure
When the mold is working, contact with the material and produce relative motion, thus causing the contact surface to gradually lose the material phenomenon called wear. grinding
The loss effect is divided into: fatigue wear of surface metal fatigue; Cavitation erosion of small pitting pits and pits formed by the rupture of the metal surface bubbles; liquid
The surface of the die surface is affected by the repeated high-speed impact of the small particles of the solid, and the surface of the mold is lost, and the abrasion and erosion of the pits and pits are formed. And in the
During friction, chemical or electrochemical reactions occur on the surface of the mold and the surrounding media, causing abrasion of the surface material. Wear is often more.
It's a form of coexistence.
3. Fracture failure
When the mold cracks or separates into two parts or more, the failure of the working ability is broken. Fracture can be divided into plastic fracture.
And brittle fracture. The mold materials are mostly brittle fracture.