The inside of the rock breaker hammer is a confined space. Except for air and hydraulic oil, if impurities or other hard objects enter, it may strain the piston of the breaker. If it is severely strained, the entire rock breaker hammer may be scrapped. Therefore, Jiama Heavy Industry recommends extensively. For rock breaker hammer users, regular maintenance of the breaker is essential to the life of the breaker. When replacing the breaker seals in three months or 600 hours, check the internal conditions of the piston and cylinder. Of course, if it is slightly strained, you can use the following Method to repair.

After the piston rod of the hydraulic cylinder is strained, it will cause the internal space of the rock breaker hammer to leak. If it is not handled in time, it will affect the normal use in the slightest, and the hydraulic cylinder will not work in the severe case. Our repair method is to repair the lighter pull marks by local grinding and polishing; for the heavier pull marks, repair by welding and manual grinding.

Formation of pull marks: After disassembling the crane, it was found that a piston rod of the luffing cylinder was severely strained, and there were 6 pull marks side by side. The main reason for the strain of the breaker parts is: after the rock breaker hammer oil seal is embrittled and fell off, not only does it lose its dust-proof function, but also a lot of dust and magazines accumulate there, causing the piston rod to directly grind with impurities, resulting in The piston rod was strained, and the scars scratched the rubber seal assembly of the cylinder mouth, causing serious leakage of the hydraulic cylinder.

Repair requirements: The filler and the base material must be firmly and smoothly combined; the seasoning must be durable and easy to be processed by hand; manual processing must ensure that the error of the piston rod diameter is less than 0.06mm. After analysis, it is determined that the filler used is J422 electrode.

Because the acid electrode is not sensitive to rust, oil and moisture, it is not easy to produce hydrogenation holes; it has good manufacturability and is easy to operate; the weld seam is beautifully formed; the material has moderate hardness and is easy to process by hand; the arc is stable and the penetration depth is large. The combination is firm.

Repair process

First clean the parts to be welded, and then use wet mud to surround the pull marks.

Choose a welding rod with a diameter of 2.5mm, adjust the current of the electric welder to 120A, and use the straight-line method to perform welding smoothly.

After all the welding is completed, remove the mud and slag, use a rough file to repair the file along the circumference of the piston rod and leave a machining allowance of 0.1-0.2mm.

A cylinder with an outer diameter of 185mm, an inner diameter of 125mm, and a length of 150mm is used as a master mold (the outer diameter of the piston rod is 125mm), which is sawn along the axis, one is a rough mold, and the other is a fine mold.

Coat the inner wall of the rough mold with a thin layer of red stamp oil, then press the rough mold against the part to be repaired on the piston rod to reciprocate several times along the axis, and then use a fine file to file off the heavier red stamp on the piston rod. Repeatedly repair the file in this way, and finally leave a machining allowance of 0.04-0.07mm.

Then use 320-mesh sand bar dipped in kerosene to match the precision mold to grind the piston rod to the specified size.

Finally, the back of the emery cloth is dipped in kerosene for manual polishing. After measurement, the maximum error is only 0.03mm.

After the rock breaker hammer of the excavator was repaired, after a year and a half of use, the luffing hydraulic cylinder has never leaked, and the piston rod is smooth and free of rust spots.