How to quickly repair gear pump hydraulic system failure (A)

CB series gear pumps are commonly used in agricultural machinery hydraulic system. After a period of gear pump performance, its performance will decline, the survey shows that the main form of gear pump damage is uniform sleeve and gear wear and scratches, the average wear is generally between 0.02-0.50mm, The depth of the mark is usually between 0.05-0.50mm. Due to agricultural time constraints, the urgent need to repair in a short time after damage, but also must take into account the service life of the gear pump after the second life and maintenance costs and maintenance work site operability. This article describes techniques for arc spraying and sticking in quick fixes. Gear pump arc spraying repair technology 1, the principle and characteristics of arc spraying Arc coating technology in the past 20 years in materials, equipment and applications developed rapidly, its working principle is to be two sprayed metal wire as a melting electrode, the motor Variable speed drives, which create a short circuit at the intersection of the gun mouth and cause an arc to melt, are atomized into fine particles with compressed air and sprayed at high velocity onto the pre-treated work surface to form a coating. It is a spray high efficiency, high bonding strength, good coating quality spraying method, with high energy efficiency, equipment investment and low cost, simple equipment, convenient and flexible operation, easy site construction and safety advantages. 2, gear pump arc spray repair process Bushing bore, bushing outer, gear shaft and pump casing uniform wear and scratches between 0.02-0.20mm, should adopt high hardness, and the body with a combination of strong , Good wear resistance arc spray repair process. Arc spraying process: the working surface pretreatment → preheat → spray bonding the bottom → spraying the working layer → cooling → coating processing. Spraying process, the requirements of the workpiece without oil, no rust, surface roughness, preheating temperature is appropriate, the bottom combined with a solid, smooth working layer, the material particles melt-bonded reliable, good wear resistance and corrosion resistance. Spray coating quality and workpieces surface treatment and spraying process has a great relationship, therefore, choose the appropriate surface treatment and spraying process is very important. In addition, the non-sprayed portions adjacent to the coated surface should be bundled with a thin sheet of metal or copper during spraying and spraying. ⑴ surface pretreatment coating and the basic bonding strength and substrate cleanliness and roughness. Before spraying, the basic surface cleaning, degreasing and surface roughening and other pretreatment is an important process spraying process. The first part of the spray should be sprayed with gasoline, acetone degreasing treatment, with a file, fine sandpaper, whetstone will be the fatigue layer and the oxide layer removed, exposing the metal color. Then roughening treatment, roughening treatment can provide surface compressive stress, increase the bonding area and clean the surface of the coating and the substrate, reduce the stress when cooling the coating, ease the internal stress of the coating, it is conducive to the increase of adhesion . Sandblasting is the most commonly used roughening process, sand to sharp, hard as well, the choice of quartz sand, emery and so on. Rough fresh surface easily oxidized or polluted by the environment, it should be timely spraying, if placed more than 4h will be re-roughened. ⑵ surface preheat treatment The temperature difference between the coating and the substrate surface will produce shrinkage stress coating, causing the coating cracking and peeling. Preheating of the substrate surface can reduce and prevent the above adverse effects. But the preheating temperature should not be too high, so as not to cause the substrate surface oxidation and affect the bonding strength of the coating and the substrate surface. Preheat temperature is generally 80-90 ℃, commonly used to complete the neutral flame. ⑶ spray-bonded primer coating before spraying the work of a thin layer of metal coating for the follow-up to provide a clean, rough surface, thereby enhancing the bond between the coating and the substrate strength and shear strength. Bottom bonding materials generally use ferrochrome nickel alloy.