The overall technical level of bearings in the world has made remarkable progress in the past 30 years. High precision, high speed, high reliability, long life, maintenance-free and standardization, unitization and generalization have become the basic technical signs of bearings. The achievements in bearing basic technology advancement, structural improvement of general-purpose products, special bearing unitization and development of ceramic bearings have been most remarkable.
(1) Basic theoretical level. Bearing basic theory mainly refers to the theory related to bearing life, rated load and limit speed. From 1980 to 1998, Ioanndeshe and Harris proposed the contact fatigue life theory to improve the bearing life calculation method. The latest theory of static load rating gives the maximum rolling element contact stress of various types of bearings corresponding to the permanent deformation of the bearing, which is equivalent to one-tenth of the rolling element diameter. The study of the limit speed of the bearing proposes the definition and limitation of the limit speed. Scope and conditions of use.
(2) Design technology level. Bearing design theory has been greatly developed, and finite difference method, finite element method, dynamics and pseudo-dynamics, elastic fluid dynamic lubrication theory, etc. have been proposed and applied. In line with this, computer-aided design has been calculated in bearing design in various countries. It is widely used. The internal structure of the bearing is improved, mainly including reducing the wall thickness of the ferrule, increasing the diameter and length of the rolling element, using the logarithmic busbar crown roller, changing the structure and parameters of the cage, changing the guiding mode, and increasing the inner seal of the bearing to improve the rib contact. Wait.
(3) Technical level of bearing products. Today's bearing product development has five distinctive features: 1 adhere to standardization, serialization, generalization; 2 to light weight, functional component, unitization and intelligent development; 3 products to high speed, high precision, high reliability , low friction, low vibration and low noise development; 4 adoption and development of computer-aided design (CAD), computer-aided manufacturing (CAM) and computer integrated manufacturing system / information management system CIMS / IMS) technology; 5 using modern high technology Such as new steel grades, new engineering ceramic materials, surface modification technology and new design structures.
(4) Process and process equipment level. In industrialized countries, large-scale standard bearings are manufactured with high-efficiency and high-precision automated equipment. For larger batches, they are organized in automated production lines, automated workshops and even automated plants. The heat treatment controls the residual content according to the dimensional stability requirements; the quantitative quantitative control is carried out according to the impact performance requirements; the reasonable hardness and matching are designed (the ferrule and the rolling element have different high hardness); in order to obtain a long life, the fine grain is studied. The requirements for the non-oxidation heat treatment process; in order to improve the impact toughness of the material, the bainite quenching process was developed. In addition, surface engineering technology is also widely used, such as laser surface impact enhancement, ion implantation and so on. In terms of machining, it has developed into high-precision, high-volume, standardized production, high-quality, high-efficiency and low-cost, and has adopted a large number of composite processes and automated production lines. The ferrule forging uses refined and semi-refined processes and equipment, such as high-speed upsetting machines, multi-station presses and cold heading machines to improve material utilization, reduce cutting volume and reduce post-processing costs. Grinding processing takes high speed and high efficiency as the development direction, and at the same time vigorously develops the grinding-super-finishing automatic production line, applying new technologies such as CBN grinding wheel grinding, adaptive grinding, on-line measurement and automatic fault diagnosis, and equipped with automatic bearing assembly line. To ensure productivity and stabilize product quality. Nano-scale bearing processing and measurement technology has made progress. At present, it has been able to carry out metallurgical quality testing of raw materials, heat treatment of parasitic detection, closed-loop control system for on-line detection of automated production line processing, high-precision roundness measurement technology and error compensation technology. Bearing inspection instruments are developing in the direction of networking, intelligence, virtualization and nanotechnology. High-precision nano-roundness measuring instruments, industrial CT non-destructive testing technology and laser technology are also applied in the bearing industry.
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