The material of the bearing ring is mainly bearing steel (GCr15, etc.), which is generally processed by turning, grinding, etc. Its machining accuracy directly affects the transmission accuracy of the bearing. In the grinding process, in addition to the dressing conditions of the grinding wheel itself and the amount of abrasive In addition to the characteristics of toughness, particle size, degree of bonding, and organization, the influence of metal cutting fluid on the grinding quality of bearing rings cannot be ignored. The cutting fluids currently used are mainly oil-based and water-based cutting fluids: mineral oil is one of the main components of oil-based cutting fluids, which can stay in water and soil for a long time and are not easy to degrade, destroying the ecological environment, and when incinerating at low temperatures Harmful substances will be produced; water-based cutting fluids are mainly emulsions, microemulsions and synthetic cutting fluids. Ordinary water-based cutting fluids contain additives and rust inhibitors such as nitrite, sulfur, phosphorus, phenol and other harmful elements. Red tides will occur when discharged into rivers, and fungicides such as phenols and formaldehyde will also harm the environment. Environmentally friendly cutting fluid uses non-toxic and harmless solvents and catalysts in a reasonable ratio to minimize environmental pollution during use and post-processing. Now an environmentally friendly cutting fluid is developed, and its extreme pressure lubricity, rust and anti-corrosion, cooling and cleaning properties are studied by comparing it with ordinary water-based cutting fluids.
Friction performance Borate ester is a multifunctional and environmentally friendly additive in water-based cutting fluid. The synergistic effect of triethanolamine oleate, borate ester and thiourea enables the cutting fluid to have lubricating and antirust functions. During the grinding process, the cutting fluid forms a physical (or chemical) adsorption film on the surface of the workpiece and the grinding wheel, and penetrates into the surface of the grinding wheel and the bearing to form a deposition film, which adheres and develops on the metal surface, under high pressure, high temperature and intense friction. The film works together, the friction reduction effect is obvious, and it shows excellent extreme pressure lubrication performance, which is beneficial to prevent or reduce the direct contact of metal surfaces and achieve the purpose of reducing adhesion. The comparison between the test load P and the friction force F of the two cutting fluids shows that with the increase of the test load, the friction forces of the two cutting fluids both increase, but the friction force of the ordinary water-based cutting fluid increases greatly, indicating that the environmental protection type The cutting fluid reduces friction better. Anti-rust properties
With the prolongation of time, the anti-rust performance of ordinary cutting fluids is obviously weakened; the test results of environmental-friendly cutting fluids in 24-36 hours are all grade A, and slight rust begins to appear after 48 hours, indicating that its anti-rust performance gradually weakens. The cutting fluid has obvious rust phenomenon; the environmentally friendly cutting fluid has obvious rust after 72h, indicating that the environmentally friendly cutting fluid can also maintain good rust resistance under long-term continuous work.
Antiseptic and bactericidal properties Water-based cutting fluid has the conditions for the growth and reproduction of microorganisms and fungi during use, and is easy to spoil and deteriorate. It is necessary to add antiseptic bactericides to inhibit the growth of microorganisms and fungi. From the tissue diagrams of the hyphae of the two cutting fluids under the microscope, it can be seen that the type, size and quantity of the hyphae of the ordinary water-based cutting fluid are significantly higher than those of the environment-friendly cutting fluid. The boron atoms in the environment-friendly cutting fluid itself have a bactericidal effect. , Boric acid is often used as a disinfectant in the pharmaceutical industry, indicating that boric acid esters can reduce the reproductive capacity of microorganisms in water-based metal cutting fluids, and have strong antiseptic and bactericidal properties. In addition, the environmentally friendly cutting fluid can achieve the effect of anti-corrosion and sterilization without adding other additives, saving costs. Workpiece surface quality The surface quality inspection of the bearing inner ring machined with the two cutting fluids is shown in Table 3. Through calculation, the arithmetic mean values of the surface roughness Ra of the specimens processed by ordinary water-based cutting fluid and environment-friendly cutting fluid are 0.821 and 0.684 μm, respectively. The surface of the test piece is free of burns and scratches after pickling. The use of environmentally friendly cutting fluids to grind and process workpieces can effectively improve the surface quality of the workpieces. The main reason is that the environmentally friendly cutting fluids have good lubrication, cooling and cleaning effects. Treatment and Discharge of Cutting Fluid At present, the most widely used water-based cutting fluid waste liquid treatment methods are physical treatment, chemical treatment, biological treatment, combustion treatment. One of the most effective treatment methods for environmentally friendly cutting fluids is to establish a cutting fluid recycling system, which collects the cutting fluids applied by each machine tool, and then transports them to each machine tool for recycling after being filtered and processed through the pipe network. For cutting fluid containing impurities such as chips and abrasive particles, it flows back to the cutting fluid waste treatment system through trenches or pipes for reprocessing, and the impurities contained in the waste fluid are collected and processed. The biodegradation rate of environmentally friendly cutting fluid can reach 90%~ 100%. The cutting fluid should be detected and maintained through the index during the use process, so as to keep abreast of the changing trend of the cutting fluid, ensure the normal processing, and prolong the service life of the cutting fluid.
Analysis of the use cost and life cycle of environment-friendly cutting fluid Environmentally friendly cutting fluids should not only have good environmental performance during use, but also have a reasonable cost of use. Ordinary water-based cutting fluid and environment-friendly cutting fluid are used in the bearing grinding production lines of workshops 1 and 2 of internal bearing grinding respectively. Both use cutting fluid recycling and reuse system. After waste fluid treatment and cutting fluid price calculation, it is found that: The cost of cutting fluid in the environmentally friendly cutting fluid production line is reduced by 50% to 60%. Through statistics, it is found that the bearing internal grinding workshop 1 using ordinary water-based cutting fluid needs to add preparations once every 2 months after the microbiological detection of the cutting fluid from January to April and from October to December, and the microbiological detection of the cutting fluid from May to September. After that, the preparation needs to be added once every month on average, the cutting fluid needs to be replaced once a year, and the waste fluid needs to be specially treated; the 2nd workshop of the bearing inner grinding that uses the environment-friendly cutting fluid needs to monitor the microbial indicators of the cutting fluid about every 6 months. The preparation is added once, and the cutting fluid is replaced once every 2 years, and the waste fluid can be effectively degraded. Therefore, the use of environmentally friendly cutting fluid not only reduces the pollution to the environment, but also improves the use cost and service cycle. By comparing the performance of ordinary cutting fluid and environmentally friendly water-based cutting fluid, it can be seen that the environmental-friendly water-based cutting fluid has good lubrication and anti-rust performance, can improve the machining accuracy and surface quality of the inner and outer rings of the bearing, and reduce the cost of use. Waste liquid treatment, life cycle and occupational health and safety are developing in a green direction.
