Several mechanical parts maintenance methods

2024-09-19 11:06:16

1, engine cylinder head deformation repair my company two Japanese Kawasaki kld85z loader, the engine cylinder head due to long-term work in high temperature, high pressure, heat load and alternating load and warping deformation, cylinder pad from the water outlet is broken, resulting in a drop in combustion chamber pressure, insufficient engine power and radiator water inlet.

The cylinder gasket was changed twice in a row, and it was washed out again after one month of use. After disassembly and inspection, it is found that the cylinder block and cylinder head are deformed. The flatness error of the cylinder block is 50μm, which also meets the technical requirements, but the flatness error of the cylinder head reaches 0.20mm, and this deformation is the main reason for the cylinder pad to be washed out.

The repair method we use is that because there is no combustion chamber concave on the cover of the machine, it is unnecessary to consider the change of the combustion volume (the change value of the combustion chamber volume should not be greater than 4% of the original volume), and the surface milling method is used to process the cylinder head plane; A copper gasket (the thickness of the copper gasket is 1.2 times the thickness of the water groove) is installed at the water channel opening on the cylinder head and the cylinder block joint surface to replace the rubber seal ring on the cylinder gasket, and then the cylinder gasket is installed, and the method of cold tightening and hot tightening is used to strengthen the cylinder head bolt. The engine repaired by this method does not have the failure of overpunching cylinder pad.

2, dry thin wall cylinder liner emergency repair

A Komatsu wa420 loader, due to long-term field work, the cooling water used by the engine contains more minerals, coupled with the neglect of the maintenance of the cooling system filter, the engine crankcase cavitation occurred at the ii cylinder, and the thin-walled cylinder liner was also cavitation, resulting in a φ2mm hole, resulting in water in the crankcase oil pan.

Considering that the machine is the equipment purchased in 1992, the crankshaft, camshaft and cylinder block of the engine have reached or are close to the limit of use, investing a lot of money to repair has no value, but the wear of the cylinder liner and piston of the engine still meet the technical standards, no burning oil and black smoke phenomenon, and the engine works normally, and the fuel consumption has not increased significantly. The hydraulic system and the chassis part can still be used, and the efficiency is obviously higher than that of the domestic similar machinery.

To this end, we will turn the original cylinder liner 180 degrees, and in the crankshaft box cavity with ab adhesive plug, and then reassemble the engine, run again to show that the work is normal. With this lesson, in the later work is normal. With this lesson, in the later work, management and maintenance personnel attach great importance to the maintenance of cooling water filters. It has been a year since the repair and the machine is still in use.

3. Processing and repair of the piston cylinder of the loading mechanism power unit

The double line pneumatic power hydraulic braking system is used on the loader, and this braking system is also used on a kld85z loader. Due to long-term use, once, the brake booster suddenly fails during use, and the reason for its failure is as following: the inner cavity of the booster hydraulic cylinder is corroded by the brake fluid for a long time, resulting in the rubber bowl wearing and failing.

After inquiry, this product has no domestic parts, and the import price is 12,000 yuan. Obviously, it doesn't make economic sense to buy it. We found that the rubber bowl in the clutch repair kit of the bj2020 Jeep is similar in size to the leather bowl of this machine, but with a slightly smaller outside diameter. After analyzing the size of piston cavity, it is concluded that this part can be machined completely by lathe. Using fast and small feed machining to reduce the roughness of the inner cavity; Adjust the tool holder 23 degrees when feeding, so that the inner wall has a certain slope; The inner diameter is determined according to the outer diameter of the leather bowl, and is 0.40.5mm smaller than its original size. After careful measurement and processing, it can be used normally after repair.

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