Hardware materials are widely used in our daily lives and can be said to be ubiquitous. The processing of metal stamping parts is inseparable from stamping die equipment, and the quality of the dies has a significant impact on the stamped parts. However, during the production process of hardware stamping dies, die explosion (die cracking) often occurs, which halts production lines and disrupts the normal production schedule of stamping plants. Below, the editors of Zhejiang Balford Electromechanical Co., Ltd. will introduce the causes of explosion in hardware stamping dies.
Die cracking in blanking dies is a very common undesirable phenomenon. Typically, the die may only develop a small notch, but in severe cases, the die can crack open, and in the most extreme situations, it can break into several fragments, thereby damaging the die and the quality of the products, ultimately leading to die explosion.
1. Selection of the Press
To extend the service life of metal blanking dies, a high-quality press should be selected. The average regrinding life of an open-back press is 10,000 to 30,000 strokes, while the die life of a new precision press can reach 60,000 to 120,000 strokes. In particular, for dies with small or zero clearance, carbide dies, and precision stamping dies, a press with high precision and good rigidity should be chosen; otherwise, the die service life will be reduced, and in severe cases, the die may be damaged.
2. Die Design Causes
Generally, if the structure is unreasonable, the strength is insufficient, the cutting edge spacing is too close, the number of die blocks is insufficient, or there are no spacers (risers), the die will have a high risk of explosion. Die design mainly includes the following aspects:
1. Strip layout and blank layout: The reciprocating feeding method often leads to die damage, and if the blank layout (web) value is too small, die wear is aggravated. Therefore, selecting a reasonable strip layout method and blank layout value can extend die life and avoid die explosion.
2. Guide rail precision: High and reliable guide rail precision can reduce guide rail wear and prevent scoring between the punch and die. This is especially important for zero-clearance and small-clearance blanking, compound dies, and multi-station progressive dies. In addition, selecting the correct guide die type and guide mechanism precision based on the processing characteristics and part accuracy is key to improving die service life.
3. Processing Technology Causes
Experimental results show that the heat treatment quality of the die has a significant impact on its performance and service life. Statistical analysis of failure causes reveals that more than 40% of die failure accidents are caused by improper heat treatment. During the manufacturing of blanking dies, improper quenching and tempering processes can cause deformation of the finished product, ultimately leading to die explosion.
1. Preheating heat treatment: Operators should adopt preparatory heat treatment methods such as annealing, normalizing, and quenching and tempering according to different die materials and requirements to eliminate structural defects in forgings and improve processing technology levels. In addition, appropriate preheating treatment of raw die materials can make carbide distribution more uniform, which is conducive to ensuring quenching and tempering quality and extending die service life.
2. Quenching and tempering: This is a critical step in die heat treatment. Excessive quenching temperature can cause brittle strengthening of the die, leading to easy deformation and fracture of the product during cooling, seriously affecting die service life. Quenching heating must be strictly carried out according to heat treatment process specifications, with special attention paid to phenomena such as oxidation and decarburization. If conditions permit, vacuum heat treatment can be adopted. In addition, tempering should be carried out promptly after quenching, and different tempering processes should be selected according to technical requirements.
IV. Surface Strengthening Treatment
In order to improve the performance and service life of stamping dies, surface strengthening treatment of die working parts is increasingly widely applied. Common surface strengthening methods include liquid carbonitriding, ion nitriding, boronizing, vanadizing, electro-spark strengthening, chemical vapor deposition (CVD), physical vapor deposition (PVD), and TD (thermal diffusion) treatment where carbides are immersed into the workpiece surface in a salt bath. In addition, surface strengthening treatments such as high-frequency quenching, hydraulic pressing, and shot peening can generate compressive stress on the surface of die working parts, improving their fatigue strength and helping to extend die service life.
The above is content related to hardware stamping dies. The selection of stamping equipment is directly related to a series of important issues such as equipment safety, production efficiency, stamping part quality, blanking die service life, and production costs. Therefore, it needs to be chosen carefully. It is hoped that the above content can be helpful to readers.