If the
Piston Rod of the hydraulic cylinder is pulled and not dealt with in a timely manner, it may affect normal use in mild cases and render the hydraulic cylinder inoperable in severe cases. Our repair method is to use local grinding and polishing to repair lighter scratches; For heavier scratches, welding and manual grinding methods are used to repair them.
Formation of pull marks: After disassembling the crane, it was found that one of the variable amplitude cylinder piston rods was severely pulled, with 6 pull marks arranged side by side. The main cause of piston rod strain is that after the dust ring becomes brittle and falls off in a block shape, it not only loses its dust-proof function, but also accumulates a lot of dust and debris, causing the piston rod to directly rub against impurities, resulting in the piston rod being pulled and the scar scratching the rubber sealing component of the cylinder mouth, causing serious leakage of the hydraulic cylinder.
Repair requirements: The filler and base material must be firmly and smoothly bonded; Seasoning must be durable and easy to process by hand; Manual processing must ensure that the diameter error of the piston rod is less than 0.06mm. After analysis, it has been decided to use J422 welding rod as the filler. Because acidic welding rods are not sensitive to rust, oil stains, and moisture, and are less likely to produce hydrogenation pores; Good craftsmanship and easy operation; Beautiful weld formation; The material has moderate hardness and is easy to manually process; The arc is stable, the melting depth is large, and it is firmly bonded to the base material.
Repair process:
(1) First, clean the area to be welded, and then surround the scratch with wet mud.
(2) Select a welding rod with a diameter of 2.5mm, adjust the current of the welding machine to 120A, and use the straight line running method to smoothly weld.
(3) After all welding is completed, remove the mud and slag, use a coarse file to file along the circumference of the piston rod, and leave a machining allowance of 0.1-0.2mm.
(4) A cylinder with an outer diameter of 185mm, an inner diameter of 125mm, and a length of 150mm is used as a reference mold (piston rod outer diameter of 125mm), which is sawed along the axis. One is a rough mold and the other is a precision mold.
(5) Apply a thin layer of red ink on the inner wall of the rough mold, then press the rough mold against the repair area of the piston rod and run it back and forth along the axis several times, and then use a fine file to remove the heavier red ink on the piston rod. Repeatedly filing in this way, leaving a machining allowance of 0.04-0.07mm in the end.
(6) Then dip a 320 grit sand bar in kerosene and use a precision mold to grind the piston rod to the specified size.
(7) Finally, dip the back of the sandpaper in kerosene for manual polishing. After measurement, the maximum error is only 0.03mm.
After one and a half years of use, the slewing hydraulic cylinder of the crane has never experienced any leakage, and the piston rod is smooth and rust free.
Repair requirements: The filler and base material must be firmly and smoothly bonded; Seasoning must be durable and easy to process by hand; Manual processing must ensure that the diameter error of the piston rod is less than 0.06mm. After analysis, it has been decided to use J422 welding rod as the filler. Because acidic welding rods are not sensitive to rust, oil stains, and moisture, and are less likely to produce hydrogenation pores; Good craftsmanship and easy operation; Beautiful weld formation; The material has moderate hardness and is easy to manually process; The arc is stable, the melting depth is large, and it is firmly bonded to the base material.