Hydraulic control valve of the electro-hydraulic valve brush plating repair process: the first to demolition seized and degreasing. Hydraulic valves are precision parts, dismantling may not be damaged or lost, it is necessary to carefully analyze the working principle, to determine the disassembly order, and make all the parts assembly mark, parts to be loaded into a special box, safekeeping. Degreasing can be cleaned with a cleaning agent, and then chemically repeated degreasing. Repair methods include grinding the valve hole and repair valve two elements. Measure the clearance between the valve hole and the valve plug. The valve hole diameter is 50 mm and the valve plug diameter is 50 mm. The clearance between the valve plug and the valve hole is seriously out of tolerance, reaching 0.07 ~ 0.15mm, and the valve plug cylinder tolerance is between 10 ~ 20μm. 1. Grinding valve hole (1) Grinding tool is mainly to restore the geometric size of the valve hole to eliminate the valve hole taper and ovality. Grinding using gray cast iron HT200 material made of grinding tools, grinding rod structure as shown in the figure, is adjustable. In order to adjust the diameter of the grinding rod and to store the abrasive, there are four grooves on the surface of the grinding rod, one of which is cut through. Grinding rod hole made of 1:20 or 1:30 taper, relying on the taper hole and matching tapered mandrel to adjust the gap between the grinding rod and the workpiece hole. When the conical mandrel position is biased toward the small head of the grinding rod, the diameter of the grinding rod increases and the gap between the grinding rod and the investigated valve hole becomes smaller. When the tapered mandrel moves to the large position of the inner hole of the grinding rod, Grinding rod cut through the slot to produce a small elasticity, leaving the grinding rod and the valve hole to be increased gap. In order to be able to be well guided during grinding, the working length of the grinding rod deep into the valve hole is about 3/4 of the length of the workpiece. The diameter of the grinding rod cylinder is usually 30 ~ 50μm smaller than the diameter of the ground to be ground to accommodate the abrasive and the material. (2) grinding selection 220 grinding paste, diluted with kerosene, applied to the grinding rod; grinding rod fixed to the lathe to 200? R / min speed rotation, holding the valve body, the grinding rod for linear reciprocating motion and Turn and polish properly before grinding. Grinding to prevent the body due to the role of self-weight to form an elliptical hole, the diameter of the valve hole after grinding 50.5mm, the valve hole of the cylindrical surface of the roundness and cylindricity shall not exceed 5μm, the cylindrical surface of the coaxial error error Above 1μm, the valve hole surface roughness Ra is not more than 0.8μm. 2. Repair spool first cylindrical grinder in the refining, to ensure that the spool of cylindrical less than 5μm. Then degreasing, the key is to pay attention to brushing the working layer before the spool surface treatment, can not allow the groove of oil or other impurities in the brush into the brush plating work surface or stick to the pen coating on the quality of brush plating . (1) brush plating process ①brush plating preparation and pretreatment. The valve core material is 35? CrMo steel, carbon steel can be medium and activated carbon surface treatment process. Activate with Activator # 2 first and then Activate with Activator # 3 at a voltage of 15 ~ 18V until a uniform silver-gray color appears on the surface. ② brush plating the bottom. With a special nickel coating as the bottom, brush plating first without electricity, with a special pen coated with nickel solution wipe the surface to be plated, which lasted 3 ~ 5s, and then under the voltage of 15V, the pen plating speed of 10m / min plating Movement, brush coating thickness 2μm. ③ brush plating working layer. According to the working conditions can choose fast nickel or dense rapid single nickel coating as the working layer, the diameter of the spool brush to 50.5mm or so. (2) grinding Grinding the valve core on the cylindrical grinder so that the clearance between the valve core and the valve hole reaches 0.015mm. 3. Assembling test Assemble the valve in the reverse order of disassembly, and pay attention to the following points when assembling: (1) Clean all the valve parts with kerosene, light diesel oil or gasoline, and remove the coated abrasives, especially the valve body Undercut groove and the valve body, the valve hole should be carefully examined the channel, there should be no residue. After cleaning, blow dry with air and dry it with care not to allow the fibers and dirt on the cloth to adhere to the part. (2) check the spool and the valve hole with the gap If there is no measuring instruments, gauges can smear a thin layer of clean oil on the spool, carefully into the valve hole, the valve hole in the full length range, Should be able to move without any movement of flexibility, rotating spool can maintain the above state after a certain angle, there is no block, you can be considered eligible. (3) Check the sealing condition of the contact surface Put clean kerosene into the valve hole, check the sealing between the valve body, the cover and the contact surface of the electromagnet housing, and do not allow leakage. Electro-hydraulic valve installed test, work well, the user to prove that its life has reached the level of the new valve. Brush plating repair costs usually only buy the new valve about 1/10, and the repair time is short, high quality, can reduce the loss caused by downtime. This article Keywords: control valve
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