Does the cold rolled ribbed steel bar machine need to frequently change the mold?
Cold-rolled ribbed steel bars are formed on the surface of the steel bars through the cold rolling process. The mold should be the key component used to form the ribs in this process.First, the material of the mold may affect its durability.Secondly, frequency of use is also a factor.In addition, the hardness of the processed material also needs to be considered,and the design of the mold is reasonable.
1. Main factors affecting mold life
Mold material and process:
High-quality molds (such as alloy steel, tungsten carbide and other wear-resistant materials) can last for thousands of tons of steel bars, while ordinary molds may only last for hundreds of tons. Surface heat treatment (such as nitriding, coating) can greatly extend the service life.
Processing material hardness:
High-strength steel (such as HRB500) wears the mold more severely than ordinary steel (HRB400), which may shorten the mold life by 30%-50%.
Equipment load:
The wear rate of molds in continuous 24-hour production may be 2-3 times that of intermittent use. For example, a case shows that the mold needs to be repaired every 2 months under continuous production, while it can be extended to 6 months under 8-hour work per day.
Rolling process parameters:
Excessive reduction (such as more than 15%) or excessive roller speed (such as >30m/min) will cause the mold temperature to rise sharply and accelerate fatigue cracks.
2. Key measures for maintenance
Daily inspection: clean steel bar debris (especially the oxide scale produced by Q235 steel) to prevent scratches on the working surface of the mold.
Lubrication management: use high-temperature grease (such as molybdenum disulfide) and replenish it every 4 hours to reduce the friction coefficient by about 40%.
Wear monitoring: use a laser micrometer to measure the rib groove depth regularly. When the deviation exceeds 0.2mm, the mold needs to be repaired. Data from a steel plant shows that timely repair can extend the life of the mold by 25%.
3. Economic replacement strategy
Cost calculation: The mold cost accounts for about 1.5%-3% of the cost of a single ton of steel bars. When the mold repair cost reaches 70% of the price of a new mold, replacement is more economical.
Batch management: It is recommended to keep 2-3 sets of molds for rotation to avoid emergency stops affecting production. For example, a company adopts a three-shift mode, and each set of molds is rotated and cooled after 200 hours of use.
Conclusion
Under standard operation and maintenance, high-quality molds can be used continuously for 3-6 months, and the annual replacement frequency is usually controlled at 4-6 times. By selecting high-performance materials, optimizing rolling parameters (such as controlling the reduction to 10%-12%), and implementing preventive maintenance, the replacement frequency can be further reduced and production efficiency can be improved by 15%-20%. It is recommended to conduct a comprehensive mold evaluation after producing 5,000-8,000 tons of steel bars.
