With the rapid development of the steel industry, in order to improve the output rate of steel, improve the utilization rate and production efficiency of the rolling mill, and reduce the number of shutdowns of the rolling mill, carbide mill rolls and roll rings have emerged as the times require, and are widely used in high-speed wire rod rolling. system.
In the early days, people mainly used the grinding process to process the cemented carbide mill rolls, but the grinding efficiency was too low, which affected the production efficiency. Finally, a tool material that can be turned instead of grinding is developed, and turning is used to replace the rough grinding process, which greatly improves the production efficiency of cemented carbide rolls and reduces production costs.
In the process of turning cemented carbide mill rolls, the hardness of the tool itself must be higher than the hardness of the workpiece to be processed. Therefore, the current cutting tool materials for turning cemented carbide rolls are mainly high-hardness, high-heat-resistant non-metallic binders cubic boron nitride and diamond. host.
Carbide roll processing methods and selection rules of tools:
1. Look at the hardness: Carbide rolls with hardness less than HRA90 can choose HLCBN material or BNK30 material for turning with large allowances, and turning carbide rolls with large allowances will not break or burn the tool. When the hardness of the cemented carbide roll is greater than HRA90, the processing range of the cubic boron nitride tool has been exceeded. Generally, the diamond tool of CDW025 material or the resin-bonded diamond grinding wheel is used for grinding. Generally, the higher the hardness, the more brittle the material will be. When the cemented carbide is cut, the cutting edge will be “slagging or chipping”, which will cause the workpiece to be scrapped. Therefore, it is more cautious to cut high-hardness materials. Either do chamfering in advance, or use accurate pre-processing. Leave fine grinding allowance to avoid.
2. Look at the machining allowance and processing method: if the outer surface or the groove above R3 of the car is processed, and the allowance is large, generally use HLCBN material or BNK30 material for rough machining, and then use a grinding wheel for grinding (resin bond diamond). Grinding wheel grinding of outer circle or plane, roll groove groove and other forming grinding generally use electroplating or metal bond diamond grinding wheel); for small machining allowance, either use grinding wheel for direct grinding, or use diamond tool for profiling processing (such as chamfering process and grooving process, you can choose customized diamond tools); generally speaking, cutting instead of grinding can improve processing efficiency, and the cutting method of carbide chips is easier to recover; because the customization of forming grinding wheel requires cycle Or a mold is required, but the non-standard customization of the forming tool is relatively fast, so the cutting method is more conducive to improving the production cycle.
3. When ribbing the crescent groove of the roll, CDW025 diamond engraving and milling cutter (also known as flying cutter, rotary cutter) is used.
4. The rolls are divided into new production and grinding. The above methods are not only suitable for reference when new rolls are produced in cemented carbide roll factories, but can also be used for grinding cemented carbide rolls in steel mills.
When machining cemented carbide mill rolls, the tool may be passivated. The so-called passivation treatment is to solve the defect of the micro-notch of the tool edge after sharpening, reduce or eliminate the edge value, and achieve smoothness and smoothness. Sharp sturdy and durable purpose. However, the passivation treatment should not be too large, because the contact surface of the cutting edge of the tool becomes larger after passivation, and the cutting resistance also increases.
Post time: Jul-13-2022