Hard turning technology and key technologies
0 Introduction Hard turning, also known as "replacement by vehicle," refers to turning hardened steel as the final finishing process. Under normal circumstances, rough machining of hardened steel parts is carried out before quenching, and after quenching, grinding is performed. However, the grinding process is costly and inefficient. With the development of high-hard tool materials and related technologies, it is possible to use PCBN tools, ceramic tools or new carbide tools to turn hardened steels on lathes or turning machining centers, and the machining quality can also reach the level of fine grinding. 1 Compared with grinding, hard turning has the following characteristics: Hard turning has the following characteristics: When the machining efficiency is high and the economic benefit is good, when removing the same volume of metal, hard turning can often use larger depth of cut and higher speed. The grinding can only use a small depth of cut, otherwise it is easy to produce grinding burns, deformation caused by large radial force, hard turning metal removal rate can be 3 to 4 times of grinding, energy consumption is only grinding 1/5; Turning one clamping can complete multi-surface machining (such as outer circle, inner hole, end surface, step, groove, etc.), grinding can not; under the same processing efficiency, lathe investment is only grinder's 1/3 ~ 1/2, small footprint, low cost of auxiliary systems. It is a cutting tool used in the hard machining of the machining process. Basically, cutting fluid is not used. This saves the related cutting fluid transmission device and processing device, which greatly saves the investment cost; the cutting fluid generally contains poisonous and harmful substances. It will cause environmental pollution and also damage the operator's health. Hard turning without cutting fluid is a clean process. Achieving good overall machining quality A reduction in the number of workpiece installations results in higher position accuracy and roundness of the workpiece, and no surface burns or micro-cracks due to turning. At present, the processing precision of hard turning can reach IT5 level, and the surface roughness Ra can reach 0.8-0.2 μm. 2 Key technologies for hard turning In the hard turning process, the cutting force is large (especially the radial force is larger than the main cutting force), the cutting temperature is high, and the tool life is short. This requires that the tool be used as a hard turning tool. Heat and wear resistance should be better and the machine tool system must have sufficient stiffness. Tool materials and geometric parameters can be used as hard turning tool materials are cubic boron nitride (CBN), ceramics and new carbide. CBN has high hardness and wear resistance and is suitable for hardened steel workpieces with hardness greater than HRC55. The cost of ceramic cutting tool materials is lower than that of CBN, and it has good chemical and thermal stability, but its hardness and wear resistance are not as good as CBN. It is more appropriate to use ceramic cutting tools for hardened steel workpieces with hardness less than HRC50. China's ceramic tool technology has been more complete, blade performance is also more reliable, domestic Al2O3, ceramic blade has nearly 20 varieties. The new cemented carbide and coated carbide cutting tool materials have higher bending strength and impact toughness than CBN and ceramic materials, and the price is low. They can be used to process hardened steel workpieces with a hardness of HRC40 to 50. The reasonable choice of blade shape and tool geometry parameters is crucial to the full play of the cutting performance of the tool. For blades of various materials, high strength, good blade shape with heat dissipation conditions, and as large a tool tip arc radius as possible should be selected. The main feature of the tool geometry parameters is to choose a larger negative rake angle or a pre-abrasive negative chamfer. Choosing the amount of cutting and cutting conditions is reasonable or not, and it has a great influence on the effect of hard turning. Because of the heat resistance and wear resistance of CBN and ceramic tool materials, higher cutting speeds, larger depths of cut, and smaller feed rates can be used. The effect of cutting on the wear of cemented carbide tools is larger than that of CBN tools. Therefore, it is not appropriate to use carbide cutting tools for high cutting speeds and cutting depths. In general, hard turning does not require cutting fluid. However, when there are special requirements on the machining accuracy, surface quality and tool life of the workpiece, it is also possible to use a water-based cutting fluid and adopt a continuous and uniform cooling method to avoid micro cracks in the blade. Hard turning machine hard turning Compared with non-hardened steel turning, the cutting force is increased by 30% to 100%, and the cutting power is increased by 1.5 to 2 times. So hard turning makes higher requirements on the machine tool, such as high Stiffness, high power and so on. In addition to ensuring high stiffness, the spindle system of the machine tool itself should also have a high rotational speed to ensure that the performance advantages of CBN or ceramic tools are fully realized. However, the spindle's high rotation speed often causes vibration. In order to prevent and eliminate vibration, the entire spindle system including the fixture must be well-balanced, and the spindle radial runout and end surface runout must not exceed 3 μm.
The precision of the machine tool guide rail is high, the linearity is better, and the clearance is smaller. In particular, there must be no crawling phenomenon. In addition, the machine tool must have good thermal stability, and the thermal deformation of the machine tool must be within a certain range, so as to ensure the processing accuracy requirements of continuous production.
3 Hard turning applications and prospects Practice has proved that hard turning ratio grinding can reduce costs by 40% to 60%. In the automotive industry in Germany and the United States, crankshafts, camshafts, and other components are machined using hard turning technology and have received good results. China also has a few factories in the CNC lathe hardened thin-walled sleeves, bearing rings, gear holes and end surfaces, and cutting tools and other parts, with hard turning to achieve the grinding effect, and improve the processing efficiency. At present, the application of hard turning technology is not enough, the main reasons are: the technical requirements of the machine, tools, fixtures and processes should have the best combination; the workpiece hardness and margin should be uniform, the study of hard turning mechanism is not enough; hard state The actual guiding role of successful turning machining examples is not strong; the promotion of hard turning effects is not enough. Despite this, hard turning with its distinctive features and advantages is bound to become one of the important directions in the field of cutting.This steel baler equipment can squeeze all kinds of scrap metal raw materials into cuboid, cylinder and other various shapes, its compression ratio is high, convenient for storage, transportation and smelting, improve the furnace feeding efficiency, suitable for scrap steel processing and distribution center, scrap car dismantling center, casting industry, steel mills and non-ferrous metal industry.
1) All structural parts are reliable and stable. The wear-resistant plate is made of Hardox plate imported from Switzerland, featuring long service life and low maintenance cost
2) The operation mode can be manual mode or automatic control mode, which is simple and easy to learn
Steel Shavings Baler, Steel Turnings Baler, Waste Steel Baler, Steel Scraps Baler
Jiangyin Metallurgy Hydraulic Machinery Factory , https://www.eco-balingmachine.com