In the manufacturing process of hydraulic valves, in order to improve the assembly accuracy, the matching method is adopted. That is, for a batch of processed parts, such as the valve body and the valve core, according to the actual size, the pair with the most suitable clearance is selected to ensure good. Spool sliding and sealing performance. That is to say, the same type of hydraulic valve, the valve core and the valve body have different dimensions. For the enterprise, when a certain number of failed hydraulic valves are large, all the valves can be disassembled and cleaned, and the parts are inspected and tested. According to the test results, the parts are classified and re-assembled according to the following methods.
The auxiliary processing of hydraulic components mainly includes: valve body cleaning, component deburring, heat treatment residue and cleaning.
1. Most of the valve body-made sand-cleaning hydraulic valve body is made of ductile iron, vermicular iron and gray iron, and is made of resin sand as a molding medium. It has small volume, compact structure, complex shape and precision. High requirements are required, and the quality of the castings largely determines the grade of the hydraulic valve. Since the valve body is made of sand as a molding material, there is inevitably a sticky sand in the casting. Sticky sand is more harmful to the hydraulic system. There are many methods for removing sand sticks. The commonly used hydraulic pumps in China include drum sand cleaning, shot blasting, electrochemical sand cleaning and water blasting. Shot blasting is generally used for valve body with large oil passage opening or larger oil passage and sand cleaning of rough valve body. It can remove not only sand and sand, but also rust and rough processing. It is liquid blasting and can also act as a surface for finishing castings. Electrochemical sand cleaning uses (SiO2) to react with molten NaOH to form sodium metasilicate and water, which can remove the sticky sand in narrow oil passages. Therefore, two methods of shot peening and electrochemical cleaning are used. The method of fine sand removal of valve body castings is widely used by various manufacturers. However, these two methods of sand cleaning also have shortcomings: (1) Sand blasting is suitable for valve bodies with large oil chambers or oil passages, which have great limitations on complex structures and small oil passages. Effectively removes the sticky sand, and is easy to cause damage to the processed surface, thus affecting the sealing, aesthetics and product precision, and is not conducive to the arrangement of the processing steps; (2) electrochemical cleaning is difficult for some non-circulating cavities to effectively The net stick sand, and the energy consumption is high, the damage to the environment is great, and the work intensity of the workers is also high. Therefore, the sand cleaning of the complicated parts is still being explored.
2. Deburring and heat treatment residue of the sliding valve parts Another major problem in the auxiliary process of the hydraulic parts is the machining of burrs and heat treatment residues. The presence of burrs will adversely affect the hydraulic components, such as the valve stem clamping, the damper hole blockage, especially the grinding in the chrome-plated stem balance groove, and the burr breaks into the valve stem with the hydraulic fluid dynamics of the oil. In the gap of the valve hole, not only can the function of eliminating the hydraulic force be eliminated, but the valve stem can be clamped, the operating force is increased, the system pressure is unstable, and the micro-motion performance and the pressure modulation performance are degraded.
When machining, reasonable cutting parameters should be used to control the generation of burrs. For the generated burrs, the process should be removed. The deburring methods are: manual operation, vibratory finishing, belt grinding, copper wire wheel or grinding. Light machine polishing method, stainless steel wire brush polishing method, liquid sand blasting method, and the like. The choice of method should be based on actual conditions. Relatively speaking, the valve body parts use a ball nylon brush or a stainless steel wire brush to remove the valve hole burr, that is, before the fine hinge, the burr generated by the cutting groove and the thick hinge is removed by the hand electric drill clamping brush. Abrasive belts or copper wire wheels are ideal for grinding burrs and rust on the outer surface of the valve. For some coarse grinding flashes, first use the steel saw blade to scrape off. Other burrs in the inner cavity can be cleaned by liquid blasting. The quenched parts can be removed by special tools or wire brushes. After quenching, the oxides can be removed by vibrating or pickling. Of course, pickling should use different acid solutions according to different materials and add suitable degreasing agent and corrosion inhibition. Agent.
3. Cleaning of hydraulic valve parts Cleaning of hydraulic valve parts is a key auxiliary process in the production of hydraulic parts. Its quality restricts the reliability and stability of hydraulic valves. The quality of cleaning has a great relationship with the cleaning method, the preparation of the cleaning solution, the cleaning equipment and the responsibility of the personnel.
Hydraulic valve assisted machining is a complex system engineering. It involves a wide range of applications, not only to provide protection from equipment, but also to continuously practice, summarize and improve the technology. It is necessary to seriously grasp and manage the management from the management. Only in this way can the auxiliary processing of the hydraulic valve be carried out. The content involved here is only some shallow experience, and it is hoped that it can be assisted by the domestic hydraulic valve. The quality of the processing has improved.