Aging is to eliminate the residual machining parts machining process. Vibration aging in the 1970s originated in the United States, and later in Germany, Britain, France has been widely used in our country from the early 1980s the introduction of the use of vibration aging process. As vibration aging is an efficient, energy saving, environmental protection and low cost aging method, compared with the traditional thermal aging and natural aging, vibration aging has the advantages of short production cycle, simple and flexible site, low production cost and no environmental pollution . Due to the incomparable superiority of VSR and the requirements of modern industry for energy and environmental protection, the application of VSR is the best choice for enterprises to improve their traditional technology to enhance their market competitiveness. In some aspects, they have replaced the traditional thermal aging and Natural aging. 1, Vibration aging mechanism and device principle 1.1, Vibration aging mechanism Workpiece in the blank manufacturing and cutting process, the internal residual stress, resulting in the workpiece in an unstable state, reducing the dimensional stability and mechanical and physical properties. Vibration aging process by hammering to eliminate residual stress in the metal workpiece. The work piece resonates under the action of periodic external force. The alternating stress in resonance is superposed with the residual stress in the work piece. After a certain period of time, the material yields locally, resulting in the slippage between the intragranular and the grain boundaries. Move to a more stable position to low energy. After this process, the macroscopic residual stress of the workpiece is transferred, reduced and homogenized, so as to reduce or eliminate the internal residual stress of the workpiece. 1.2, the principle of vibration aging device Mechanical vibration aging devices include exciter, control panel, acceleration sensor, support rubber and other parts. The main function is to control the exciter output level at a certain excitation force and work at any frequency with a higher frequency stabilization frequency at a certain frequency (speed) range. Especially when the load characteristics change sharply before and after the formant, And record, identify and output the aging curve and parameters. 2, the valve plate vibration aging process Vibration aging effect depends on the choice of vibration aging process. As shown in Figure 2 is a metallurgical butterfly body, is cast from the structure, its complex shape, relatively rigid, convex and concave surface, uneven wall thickness, large residual stress and complicated distribution. In the past, the process of using natural aging has many shortcomings. Since a company started using the VSR technology in 2005, great progress has been made in product quality and production efficiency. Years of production experience show that: Due to the complexity of the process of vibration aging, the box must be part of the vibration before the process analysis, design and optimization of vibration parameters to improve the effect of vibration aging. 2.1 Process Analysis In accordance with the vibration failure of the technical specifications, the workpiece aging process analysis should be carried out in order to achieve the purpose of saving power and working hours. First of all, we should analyze the distribution of residual stress field, the requirements of dimensional accuracy, the working load and the possible causes of failure according to the material, structure and the manufacturing process and process of the blank, and then decide the implementation of vibration Aging process line and the key points of aging. Metallurgical butterfly body generally treated by the box-like workpieces, the structure of such workpieces are generally more complex, poor conditions of stress. Box blank is generally cast or welded components, the residual stress generated by the casting should be based on the casting process, such as the shape of the structure, the location of the gate, thin wall thickness and cooling conditions to analyze the case of stress. For welding, the order of pre-welding and post-welding of each welding part, the size of groove and the shape and position of welding seam have an impact on the size and distribution of residual stress. According to the analysis of the loading condition of the box during service, the working load of the box body is often complicated. Since the metallurgical butterfly valve body is mainly subjected to bending deformation during the work, the failure vibration of the workpiece mainly adopts bending vibration mode. 2.2, the optimization of process parameters Vibration aging process parameters include excitation point, support point, excitation frequency, excitation force and excitation time, the selection of these parameters should be based on the inherent vibration characteristics of the workpiece to determine. When the excitation frequency in the vicinity of the workpiece's natural frequency, with a small excitation force can be excited enough dynamic stress, only the workpiece with the natural frequency excitation, in order to be the most economical, easiest and most quickly reduce the workpiece Residual Stress. However, it has been found in practice that due to the size of the exciting force, the frequency of the exciting force and the position of the exciting point are not reasonable, the effect of eliminating the residual stress sometimes occurs. The workpiece only partially eliminates the residual stress; sometimes, Workpiece shattered. Therefore, it is necessary to optimize the design of vibration aging process parameters. According to "Vibration Aging Equipment Operation Manual" in the operation requirements, before the vibration on the workpiece multi-point frequency sweep, sweep sweep at the same time and trace the vibration before the process curve and print parameters, all natural frequency sweep curve corresponding to find out Effectively eliminate the effective vibration mode (and the corresponding effective frequency) of the stress in the key part of the workpiece and directly apply the effective frequency (effective mode), print the gt curve online to observe the aging process, decide when to stop and then pass Frequency (mode) local sweep and local printing. 2.3, the evaluation of the aging effect Vibration aging effect mainly refers to the parts after vibration residual stress elimination, homogenization, anti-deformation ability to improve and dimensional stability of the degree of stability. In the production site often used in accordance with Figure 3 shows the amplitude of the time (At) curve using the following method to quickly determine the effect of vibration aging: (1) detection amplitude-frequency curve changes in the shape of the resonance peak amplitude-frequency curve showed formant (2) the change of the resonant frequency of the inspection side; (3) the change of the amplitude of the part and the excitation power during the vibration detection, if the excitation energy can be kept the most unchanged, the amplitude will rise; if the control amplitude Constant, then the excitation power is reduced. In the event of such a situation, it is determined in practice that the vibration aging has achieved its intended purpose. 2.4, Vibration aging test before and after the residual stress In order to quantitatively understand the effect of vibration aging process, the use of magnetic stress meter, excavation platform and other work pieces measured at the weld residual stress after vibration aging. The measurement results show that before the vibration treatment of the workpiece, the weld residual stress concentration is more serious. In the weld center area, the stress is high, the maximum shear residual stress is about 54-67MPa, which is close to allowable safety shear stress, which is unsafe residual stress. In the weld non-central area of ​​lower stress, about 30-50MPa. After vibration aging treatment, the residual stress concentration in the weld has been eliminated. The stress values ​​in the weld center and non-weld areas are similar. The peak residual stress has decreased from 60 MPa to 25 MPa, and the descending rate is about 60%. Less than permissible safety shear stress. 2.5 Vibration aging should pay attention to several issues (1) the occurrence of forced resonance: With the vibration frequency increases, the motor current has been rising without a downward trend, then forced resonance occurs, this phenomenon is generally by the vibration Workpiece weight is too small and too rigid caused. (2) Can not find the resonance region: It is found in the sweep process that as the frequency increases, the armature current also increases slowly, but the current is not large, until the end of the sweep acceleration is always increasing and small, this phenomenon Generally due to the workpiece's natural frequency beyond the device's control frequency range. For the above situation, through the experimental method can be solved. Repeatedly changing the excitation force and the supporting point and the clamping position of the vibration exciter; adopting a cantilever method (a method of fixing one end of the workpiece and installing the exciter on the other end), a combination vibration method Rigidly linked together to reduce the natural frequency of the workpiece). 3, Vibration aging process management and economic benefits In the production practice, a company through the vibration aging process curve to detect vibration aging effect. Each vibration aging treatment of a workpiece, must have a corresponding vibration aging process curve, the process curve, to go through the quality inspection department according to the process of the development of the Vibration Process card standard curve for acceptance, if not up to the acceptance criteria Rework to revive. Acceptance of qualified workpieces to go to the next process, effectively ensure the quality of vibration aging process is stable and reliable. Since 2005, the company has cumulatively treated 1,500 butterfly valve box-type weldments by vibration-aging, with an average mass of about 0.5 tons for each welded structure and a total processing capacity of about 750 tons. The company purchased a set of vibration aging equipment, equipment purchase costs 60,000 yuan, the operator 1 person, 4 years total salary of 80,000 yuan, vibration aging equipment daily power consumption of 16 degrees per kilowatt in accordance with 0.8 yuan , 4 years total use of electricity is 6,000 yuan. The total cost of 4 years cumulative vibration aging is 146,000 yuan. If the use of thermal aging, the need to buy thermal aging furnace, because of environmental pollution problems, can not use coal thermal aging, can only use the electric furnace thermal aging. In accordance with the company's production, the need to buy two 100kW electric furnace, equipment investment of about 300000 yuan, electric furnace power consumption, the integrated thermal aging cost 500 yuan / ton, processing 750 tons of work, need 375000 yuan. The total cost of 4-year cumulative thermal aging needs 755,000 yuan. Compared with thermal aging, vibration aging can save the cost of aging 600000 yuan, in addition, the use of vibration aging and thermal aging compared to save a large number of working hours have not been included, we can see that the application of Vibration Aging technology is equivalent to the economic benefits obviously.
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