How to extend the life of the blow mold
2024-07-19 14:05:23
The research shows that the service life of the mold is related to many factors such as improper heat treatment, improper material selection, unreasonable mold structure, unreasonable mechanical processing, poor mold slippage and poor design level. According to the analysis and statistics of a large number of failed molds, among the various factors causing mold failure, improper heat treatment accounts for about 45%, improper material selection, unreasonable mold structure accounts for about 25%, and process problems account for about 10%; slip problems, equipment problems Other factors account for about 20%.
With the continuous improvement of industrial automation, the application of molds is more and more extensive. However, in many enterprises in China, the service life of molds is still relatively low, only 1/3~1/5 of foreign countries. The low life of the mold and the poor precision of the working part will not only affect the quality of the product, but also cause huge waste of cost such as mold material and processing time, greatly increase the cost of the product and reduce the production efficiency, which seriously affects the competitiveness of the product. Therefore, in the mold design and manufacturing process, the appropriate materials are selected, the mold structure is rationally designed, a reasonable heat treatment process is selected, the processing route of each part of the mold is properly arranged, and the working conditions of the mold are improved to improve the quality and use of the mold. life.
Reasonable selection of mold materials
1.1 Reasonable mold structure
The principle of mold design is to ensure sufficient strength, stiffness, concentricity, neutrality and reasonable blanking clearance, and reduce stress concentration to ensure that the parts produced by the mold meet the design requirements. Therefore, the main work of the mold is zero (such as the convex and concave die of the die, the movement of the injection mold, the fixed die, the upper and lower die of the die forging die, etc.), which requires high guiding precision, concentricity and neutrality, and punching. The gap is reasonable.
When designing a mold, the important considerations are:
1 When designing the punch, attention must be paid to the guide support and alignment protection. In particular, the design of the small hole punch uses its own guiding structure to extend the life of the mold.
2 For weak parts such as angles and narrow grooves, in order to reduce stress concentration, a circular arc transition is required, and the radius R of the arc may be 3 to 5 mm.
3 For the complicated structure of the concave mold, the inlaid structure can also reduce the stress concentration.
1.2 Selection of mold materials
When selecting mold materials, they should be selected according to different production batches, process methods and processing objects. In mass production, long-life mold materials, such as hard alloys, high-strength, high-wearing mold steels (such as YG15, YG20) should be used. For small batches or new products, zinc alloys, bismuth-tin alloys, etc. can be used for trial production. Mold material; for general molds that are easy to deform and break easily, high-strength, high-toughness materials (T10A) are required; hot forging dies are required to have good toughness, strength, mold resistance and resistance to cold and heat fatigue. Materials (such as 5CrM-nMo); die-casting molds should use alloy steel with high thermal fatigue resistance and high temperature strength (such as 3Cr2W8V); plastic molds should be made of materials that are easy to cut, dense, and polished. In addition, when designing the punch and the die, it is preferable to match the molds of different hardness or different materials, such as: tool steel for punch (such as T10A), high carbon and high chromium steel for die (such as Cr12, Cr12MoV), The mold life can be increased by 5 to 6 times.
With the continuous improvement of industrial automation, the application of molds is more and more extensive. However, in many enterprises in China, the service life of molds is still relatively low, only 1/3~1/5 of foreign countries. The low life of the mold and the poor precision of the working part will not only affect the quality of the product, but also cause huge waste of cost such as mold material and processing time, greatly increase the cost of the product and reduce the production efficiency, which seriously affects the competitiveness of the product. Therefore, in the mold design and manufacturing process, the appropriate materials are selected, the mold structure is rationally designed, a reasonable heat treatment process is selected, the processing route of each part of the mold is properly arranged, and the working conditions of the mold are improved to improve the quality and use of the mold. life.
Reasonable selection of mold materials
1.1 Reasonable mold structure
The principle of mold design is to ensure sufficient strength, stiffness, concentricity, neutrality and reasonable blanking clearance, and reduce stress concentration to ensure that the parts produced by the mold meet the design requirements. Therefore, the main work of the mold is zero (such as the convex and concave die of the die, the movement of the injection mold, the fixed die, the upper and lower die of the die forging die, etc.), which requires high guiding precision, concentricity and neutrality, and punching. The gap is reasonable.
When designing a mold, the important considerations are:
1 When designing the punch, attention must be paid to the guide support and alignment protection. In particular, the design of the small hole punch uses its own guiding structure to extend the life of the mold.
2 For weak parts such as angles and narrow grooves, in order to reduce stress concentration, a circular arc transition is required, and the radius R of the arc may be 3 to 5 mm.
3 For the complicated structure of the concave mold, the inlaid structure can also reduce the stress concentration.
1.2 Selection of mold materials
When selecting mold materials, they should be selected according to different production batches, process methods and processing objects. In mass production, long-life mold materials, such as hard alloys, high-strength, high-wearing mold steels (such as YG15, YG20) should be used. For small batches or new products, zinc alloys, bismuth-tin alloys, etc. can be used for trial production. Mold material; for general molds that are easy to deform and break easily, high-strength, high-toughness materials (T10A) are required; hot forging dies are required to have good toughness, strength, mold resistance and resistance to cold and heat fatigue. Materials (such as 5CrM-nMo); die-casting molds should use alloy steel with high thermal fatigue resistance and high temperature strength (such as 3Cr2W8V); plastic molds should be made of materials that are easy to cut, dense, and polished. In addition, when designing the punch and the die, it is preferable to match the molds of different hardness or different materials, such as: tool steel for punch (such as T10A), high carbon and high chromium steel for die (such as Cr12, Cr12MoV), The mold life can be increased by 5 to 6 times.
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