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Reason and Repair Method of YHB Vertical Gear Pump Camshaft Breaking Fault

1, the cause of the malfunction

YHB vertical gear pump camshaft and pump drive shaft coupling. YHB vertical gear pump cam lift is 10mm, sub-pump center distance of 40mm, the maximum pump speed of 1000 rev / min. Due to high speed working conditions and the installation form of "four-point support" and improper use and maintenance, etc., the circular arc surface of the pump body of the YHB vertical gear pump and the bracket are worn out (the abrasion on the arc surface of the bracket is relatively small) Pump down, so that the camshaft and pump drive shaft offset. YHB vertical gear pump camshaft by the twisting, bending and swinging and other forces generated additional alternating stress, eventually leading to camshaft fatigue fracture.

2, repair methods

YHB vertical gear camshaft journal surface finish of not less than 8, the hardness of not less than HRC45, cylindricity tolerance of 0.10mm, full-length straightness tolerance of 0.05mm, are precision parts. For the repair of camshaft rupture, Po Taibang generally use the "replacement repair method", that is, replace the camshaft. However, after the replacement of repair if not ruled out the root causes of camshaft fracture, will inevitably lead to camshaft rupture again. To avoid repeated camshaft fractures, it is common practice to replace the pump or YHB vertical gear pump assembly. This approach is neither economical nor difficult to guarantee (the method of replacing the pump is required to use a test bench pump), especially in field conditions, the protection is more difficult. After many years of practice, the following three kinds of emergency methods, more suitable for field conditions YHB vertical gear pump camshaft rupture repair.

2.1 original repair method

The root cause of the camshaft rupture is the wear of the YHB vertical gear pump body. Based on this, we can weld the pump body with the "heap fill" welding method, the thickness of the heap compensation and slightly larger than the amount of wear and tear. Welding after the use of methods of cutting and grinding the welding parts polished flat, restore the original geometry of the pump body, cleaning the various parts, installed after commissioning can be used. Original repair method can also use metal glue make up method, YHB vertical gear pump body repair. That is, the prepared metal glue is coated on the worn area, the thickness and area of the metal adhesive coating is slightly larger than the wear amount. After the metal glue is solidified for 20 to 30 minutes, the area coated with the metal glue is polished and polished, Installed to use after debugging.

2.2 parts spelling method

YHB vertical gear pump body material is generally cast iron or aluminum alloy, despite the different materials, the installation of the same size and internal structure. Therefore, can be scrapped 6135 diesel engine type B, according to the need to disassemble available pump body, camshaft and other parts, assembled into a complete YHB vertical gear pump, installed after debugging qualified use.

2.3 additional parts method

In the field conditions, can not use the "original repair law" and "parts dismantling method", you can use the "additional parts law." The specific method is: ① with a knife and grinding abrasive cloth to wear and tear parts of the pump grinding (wear parts with the bracket with the surface, and by the end of the pump drive shaft is more serious); ② with a deep caliper after abrasion measured by the pump The depth of the site, the wear depth is generally between 0.5 ~ 1mm; ③ made of copper or iron pieces into additional parts gasket. The thickness of the additional part is determined according to the depth of the worn part measured. The width of the additional part is about equal to the thickness of the bracket. The length of the additional part is approximately equal to the arc length of the worn part of the pump body. ④ Attach the prepared gasket to the bracket and the pump Body wear between parts. The number of additional gaskets is determined according to the depth of the worn parts measured, generally not more than three; ⑤ start the test after installation and adjustment, delivery. 3, preventive measures

YHB vertical gear pump body wear is mainly due to the relatively loose pump body and bracket caused. Therefore, we can prevent it from the following three aspects.

3.1 installation should be correct

YHB vertical gear pump often due to uneven supply of fuel for each cylinder, fuel supply interval angle is not allowed to remove the overall reasons for repair, the whole pump after the installation. Installation should pay attention to the following points: ① fixed bolt diagonal tight. If the first tight outside or on the side of the body by two bolts, on the one hand may result in a good adjustment of the fuel supply advance was destroyed. The first fixed by the body side of the two fixed bolts, advance advance angle of oil supply; first fixed outside the two fixed bolts, fuel supply ahead of schedule in advance. On the other hand may cause YHB vertical gear pump camshaft axis and pump drive shaft, the installation has been offset, the engine starts, the camshaft directly under additional alternating stress and fatigue fracture. ② fixed bolts should be sub-2 to 3 times tight. ③ The tightening torque of the fixing bolt should be between 1.5 ~ 2.5kg (the fixing bolt is M8 × 1 or M10 × 1 fine thread, the tightening torque is too big and easy to damage the thread); ④ The fixing bolt should be tight in place . In practice, two fixing bolts close to one side of the body often appear, which are not tightly fixed because of the installation position, but the two fixing bolts on the outside are tightly over-adjusted.

3.2 Maintenance should be appropriate

YHB vertical gear pump diesel engine fuel supply system is an important component. In the use and maintenance process should pay attention to the following three points:

① the number of oil pump, the quality to meet the requirements. Such as poor lubrication, ranging from the pump drive components early wear and tear, heavy bearing stuck, resulting in camshaft was broken.

② camshaft axial clearance should be appropriate. Camshaft axial clearance is generally about 0.03 ~ 0.15mm, the gap is too large, the camshaft wear and tear accelerated, the engine is not running smoothly, causing the pump early wear and tear. Oil pump advance angle and the cylinder oil supply interval angle to meet the requirements. If the fuel supply advance angle and the interval between each cylinder oil supply do not meet the requirements, not only will the engine power, economic deterioration, but also cause the engine start difficult, unstable operation, leading to pump wear and tear accelerated.

3.3 check to be timely

Pump and stent loose situation, usually during the week to carry out inspection. If you find the engine has abnormal conditions or loose body, should be promptly checked tight. Check the tight method according to the installation requirements.

The above is the YHB vertical gear camshaft fracture failure causes, repair methods and preventive measures introduced.

Practice has proved that the above emergency methods and preventive measures are scientific, reasonable, feasible and practical, with high military and economic benefits.