Hydraulic oil cylinder is the most important part of construction machinery, and it is also the most prone to problems, especially the internal surface scratch of oil cylinder is more common. If the hydraulic cylinder is not repaired in time after being pulled, it will lead to premature damage. In order to restore its characteristics in a short time, the damaged hydraulic cylinder can be repaired by brush plating and brazing.

1. Clean oil stains

① First, remove oil stains and impurities on the surface. Fix the parts on the workbench, clean the oil stains on the parts with metal cleaner, and completely scrape off the oil stains and impurities on the parts with triangular scraper or other methods.

② Scrub the inner surface of hydraulic cylinder with toluene.

(3) Electrochemical cleaning with electric cleaning solution, the voltage is 12~15V, the parts are connected to the negative electrode, and the cleaning time is 60 ~ 90 s. 。

④ After electrochemical cleaning, rinse it off with clean water.

2. Activity

① No.2 activation liquid is used as electrochemical decontamination, with the purpose of removing the oxide on the parts. Connect the anode of the part, the voltage is 10~12V, and the time is controlled for 40~60s.

② When the service parts are black or dark gray, rinse them off with clean water.

(3) After washing with clean water, electrochemical cleaning is carried out with activating liquid, in order to thoroughly remove impurities in the parts' tissues. The parts are connected to the anode, and the voltage is L6 ~ 20V, and the time is 50 ~ 90s.

④ After the surface of the machine is silvery, rinse it with clean water.

3. Brush nickel plating quickly

(1) Flash nickel plating on the surface of the processed parts, the voltage is 18V, the parts are connected to the negative electrode, and the plating pen swings rapidly.

② After flash plating for 3 ~ 5s, when the surface of the part is pale yellow, reduce the voltage to 12V, brush plating rate to 9~11m/min, and continue brush plating.

③ When the thickness of nickel coating reaches 1~3μm, wash it with clean water.

4. Brush plating alkaline copper layer

① After nickel plating is rapid, brush the alkaline copper layer. When plating alkaline copper solution, the voltage is 6-8-8V, the parts are connected to the negative electrode, and the brush plating rate is 9-14m/min.

② After the alkali copper layer is increased to 20~500μcm, rinse it with clean water.

5. Brazing alloy

① Dry the surface of the brushed parts with clean silk cloth, coat zinc oxide flux on the parts that need repair welding, and then repair weld the brazing alloy to the strained parts with 300-500w electric ferrochrome in turn until the required size.

② Finally, scrape the brazing alloy layer to the required shape with a scraper, and then polish it with oilstone.

Step 6 clean

① Clean the surface of drilling layer with electric cleaning fluid to remove oil and impurities.

② Remove the oxide on the surface with No.2 activating solution. Strictly control the electrochemical cleaning time to prevent the alloy surface from blackening.

③ Remove impurities with No.3 activating solution first, and then quickly brush alkaline copper on the brazing surface.

7. Brush plating alkaline copper

① The purpose of brushing alkaline copper is to improve the strength of brazing surface. Brush plating voltage is 6~88V, the parts are connected to the negative electrode, brush plating rate is 9~14m/min, and the thickness of alkaline copper is 30~50μcm.

② After cleaning with clean water, brush nickel plating, the brush plating voltage is 12V, the parts are connected to the negative electrode, the brush plating rate is 9m/min, and the rapid nickel plating thickness is 60μm m.

③ Rinse the parts with clean water, dry them with clean silk cloth and then install and use them.