Mold burst reason. metal tubing
1 mold material is not easy to break in the follow-up processing
2. Heat Treatment: Improper deformation due to quenching and tempering
3 mold grinding flatness is not enough to produce deflection deformation
3. Design process: mold strength is not enough, knife edge spacing is too close, mold structure is not reasonable, the number of template blocks is not enough
4. Improper wire cutting: Pull wire cut, gap is not correct, no clean corners
5. Selection of punching equipment: punch tonnage, punching force is not enough, mold adjustment is too deep
6. The material is not smooth: There is no demagnetization before production, no return tip; there are broken springs and other cards in the production
7. The material is not flowing smoothly: There is no leakage during the assembly of the mold, or the roller is blocked and the foot is blocked.
8. Production awareness: laminated stamping, positioning is not in place, air blow guns are not used, cracks in the formwork continue production. metal tubing
Die failure form
The failure modes of the die are mainly wear failure, deformation failure, fracture failure, and failure of a bruising. However, due to different stamping processes and different working conditions, the factors that affect die life are many. In the following, the impact factors of the die life are analyzed comprehensively in terms of the design, manufacture and use of the die, and corresponding improvement measures are taken. metal tubing
1, stamping equipment
The precision and rigidity of the stamping equipment (such as the press) have an extremely important effect on the die life. The stamping equipment has high precision and rigidity, and the life of the die is greatly improved. For example, the complex silicon steel die material is Crl2MoV, which is used on ordinary open presses and has an average regrinding life of 1 to 30,000 times. However, on the new precision presses, the resurfacing life of dies can reach 6 to 120,000 times. In particular, small gaps or gapless dies, hard alloy dies, and precision dies must be selected with high precision and good rigidity. Otherwise, the life of the dies will be reduced, and in serious cases, the chess can be damaged. metal tubing
2, mold design
(1) The accuracy of the guide mechanism of the mold. Accurate and reliable guidance is more effective in reducing the wear of mould working parts and avoiding the great influence of convex and concave die bruising. In particular, gapless and small clearance blanking die, compound die and multi-position progressive die are more effective. In order to improve the life of the mold, the guide type and the accuracy of the guide mechanism must be correctly selected according to the requirements of the nature of the process and the accuracy of the parts. Die up to people WeChat public number, up to share experience. Under normal circumstances, the accuracy of the guide mechanism should be higher than the convex and concave mold fitting.
(2) Die (convex, concave die) edge geometry. The shape of the convex and concave molds, the fit clearance, and the radius of the fillet not only have a greater impact on the stamping part, but also have a great influence on the wear and life of the mold. For example, the clearance of the mold directly affects the blanking quality and die life. If the accuracy is higher, a smaller clearance value should be selected; otherwise, the clearance can be increased to improve the life of the mold. metal tubing
3, stamping process
(1) Raw materials for stamping parts.
In actual production, due to the excessive thickness tolerance of raw materials for external pressure parts, fluctuations in material properties, poor surface quality (such as rust), or unclean (such as oil stains), etc., wear of the mold working parts will be aggravated, and easy to chipping. as a result of. To this end, it should be noted: 1 as far as possible the use of stamping process of good raw materials, in order to reduce the stamping deformation force; 2 stamping should strictly check the brand of raw materials, thickness and surface quality, etc., and wipe clean raw materials, if necessary, should remove the surface Oxide and rust; 3 According to the stamping process and the type of raw materials, if necessary, softening treatment and surface treatment can be arranged, and appropriate lubricants and lubrication procedures can be selected. metal tubing
(2) layout and take the edge.
Unreasonable reciprocating feed layout methods and excessively small bridging values often result in rapid tool wear or convex or concave die damage. Therefore, in consideration of improving the use of materials, it is necessary to reasonably select the method of layout and the margin value in accordance with the processing volume, quality requirements of the parts, and the clearances for the mold assembly, so as to increase the life of the mold.
4, mold material
The impact of mold materials on the life of the mold is a comprehensive reflection of Gango Soo, such as material type, chemical composition, structure, hardness, and metallurgical quality. Die life of different materials is often different. To this end, two basic requirements are put forward for the working part material of the die: 1 The performance of the material should have high hardness (58~64HRC) and high strength, and have high wear resistance and sufficient toughness, heat treatment deformation is small, there is a certain Hardness; 2 process performance is good. The processing and manufacturing process of die working parts is generally more complicated. Therefore, it must have adaptability to various processing technologies such as malleability, machinability, hardenability, hardenability, quench cracking sensitivity, and grinding processability. Generally, according to the material characteristics, production volume, and precision requirements of the stamping parts, mold materials with excellent properties are selected, taking into consideration the processability and economy. metal tubing
5, hot processing technology
Practice has proved. The hot processing quality of the mold has a great influence on the performance and service life of the mold. From the analysis and statistics of the cause of the failure of the mold, it can be known that the “accident” caused by improper heat treatment accounted for more than 40% of the mold failure. The quenching deformation and cracking of the working parts of the mould and the early fracture of the working process are all related to the hot processing technology of the fixture.
(1) Forging process, this is an important part in the manufacturing process of mold working parts. For the tooling of high-alloy tool steels, the technical requirements for the metallographic structure of the material, such as the distribution of carbides, are usually put forward. In addition, the forging temperature range should be strictly controlled, the correct heating specification should be established, the correct forging force method should be used, and the slow cooling or timely annealing after forging should be adopted. metal tubing
(2) Prepare heat treatment. The heat treatment process of annealing, normalizing, or quenching and tempering should be adopted separately depending on the materials and requirements of the working parts of the mold, in order to improve the organization, eliminate the defects of the forging blanks, and improve the processing technology. High-carbon alloy die steels can eliminate meshed secondary cementite or chain carbides through proper preliminary heat treatment, which can spheroidize and refine carbides and promote the distribution of carbides. This will help ensure the quality of quenching and tempering and improve the life of the mold.
(3) Quenching and tempering. This is a key part of the mold heat treatment. If overheating occurs during quenching and heating, not only the workpiece will cause large brittleness, but also it will easily cause deformation and cracking during cooling, which will seriously affect the life of the mold. Special care should be taken to prevent oxidation and decarburization when die quenching is heated. Strictly control the heat treatment process specification. If conditions permit, vacuum heat treatment can be used. After quenching, it shall be tempered in time, and different tempering processes shall be adopted according to technical requirements.
(4) stress relief annealing. The mold working parts should be annealed and annealed after rough machining. The purpose is to eliminate the internal stress caused by rough machining, so as to avoid quenching and excessive deformation and cracking. For molds with high precision requirements, after stressing or electro-machining, they need to undergo stress-reducing and tempering treatment, which will help stabilize the precision of the mold and increase the service life. metal tubing
6, the processing of surface quality
The quality of the mold work parts plus surface quality has a very close relationship with the wear resistance, fracture resistance and anti-adhesion ability of the mold, which directly affects the service life of the mold. In particular, the surface roughness value has a great influence on the die life. If the surface roughness value is too large, stress concentration will occur during operation, and cracks will easily occur between peaks and valleys, which will affect the durability of the die, and will also affect the The corrosion resistance of the workpiece surface directly affects the service life and precision of the die. Therefore, the following items should be noted:
1 Mold working parts must be prevented from grinding the surface of burned parts in the process of machining. Grinding process conditions and technological methods (such as grinding wheel hardness, grain size, coolant, feed rate, etc.) should be strictly controlled;
2 In the process of machining, the surface of the working part of the mold should be prevented from leaving marks. Interlayers, cracks, impact scars and other macro defects. metal tubing