Flame Spray Repair of Heavy Duty Machine Tool Rails

       During the overhaul and maintenance of the machine tool, it is often encountered that the guide rails of the sliding parts are worn or scratched, and it is required to spray repair. However, since the repaired guide rail is not allowed to deform, and the large machine tool guide rail is very difficult to preheat due to its large size. The TDQ20206 gantry planer guide rail and the T62160 floor boring machine column guide rail were successfully repaired by oxygen-acetylene flame spraying without preheating.



(1) Spraying objects. The guide rail of the 6m gantry planer was scratched and worn, the spraying area was 12m long and 50mm wide, the coating thickness was 1~2mm, and the cross-sectional area of the bed was 580mm high and 260mm wide.



(2) Spraying process



1) Surface pretreatment. Use gasoline and trichloroethylene to remove the oil stains on the surface of the workpiece, brush the surface and grind the edges into rounded corners, and repair the scratches with a depth of less than 1mm to a depth of about 1mm, and remove the surface layer to be sprayed to reveal the metallic luster.



2) Spray the adhesive bottom layer. Spray aluminum-coated nickel powder, and the thickness of the bottom layer should be controlled at about 0.15mm, which should not be too thick.



3) Spray the transition layer. The powder used for the spraying transition layer is the mixed powder of aluminum-clad nickel and "Powder 11" (product of Shanghai Nonferrous Metal Welding Materials Factory), and the coating thickness is about 0.3mm.



4) Spray the working coat. Use "Powder 111" until the predetermined thickness is reached, the spray gun is QSH-4, the spraying distance is 170~190mm, the oxygen pressure is 0.4~0.5MPa, and the acetylene pressure is 0.1~0.12MPa.



Since the surface of the guide rail to be sprayed is 12m long, it is impossible to finish spraying at one time, and it must be sprayed section by section, about 1m each time. However, it is necessary to deal with each joint, that is, use a grinding wheel to grind the coating of the previous joint into a gentle slope state, so as to create good joint conditions for the next spraying.



(3) Cooling. In order to prevent the coating from peeling off during the cooling process, the temperature of the workpiece should be controlled at about 100°C.



(4) Effects. For large parts that cannot be preheated, it can be directly repaired, and the equipment is simple and economical. Improved wear resistance and extended service life after repair.