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In the actual operation process, some use and maintenance personnel have a lot of wrong practices, affecting the normal use of long spiral drilling rigs.
Do not check the plunger stroke margin
In the satirical test of the plunger-type fuel injection pump, many maintenance personnel did not pay attention to checking the plunger's travel allowance. The so-called plunger stroke margin refers to the amount of movement that the plunger can continue to ascend after it is top-dead-centered on the camshaft. After adjusting the start time of fuel supply, the reason why the travel allowance is also checked is because the stroke allowance of the plunger is related to the wear of the plunger and the sleeve. After the plunger and sleeve are worn out, the plunger must move upwards for a while to start oil supply, thereby delaying the start of oil supply. When the adjustment bolt is screwed out or replaced with a thicker adjustment pad or spacer, the lowermost position of the plunger moves upwards, so that the stroke margin of the plunger is reduced. Therefore, when repairing and debugging the fuel injection pump, it is firstly necessary to check the travel allowance to determine whether the injection pump also allows adjustment. During the inspection, the following different methods should be used according to the different structures of the fuel injection pump: a) Turn the camshaft, push the plunger to the top dead center, remove the oil valve and valve seat, and measure with a deep vernier. b) After the plunger is topped to the top dead center, lift the spring seat of the plunger spring with a screwdriver to raise the plunger to the highest point. Then use a thick gauge inserted between the plunger lower plane and the tappet adjustment bolt to measure. The standard travel distance of the plunger is about 1.5mm, and the limit stroke residual after wear is not to be less than 0.5mm.
Avoid the piston open flame heating
Because the auger piston and piston pin are interference fit, when installing the piston pin, the piston should be heated to expand. At this time, some maintenance personnel will directly heat the piston on an open flame. This is very wrong. Because the thick and uneven parts of the piston, the extent of thermal expansion and contraction will be different, the heat will make the piston heated uneven, easily lead to deformation; the piston surface will be attached to charcoal, reducing the life of the piston. If the piston cools naturally after reaching a certain temperature, its metallurgical structure will be damaged and wear resistance will be greatly reduced, and its service life will also be significantly shortened. When installing the piston pin, the piston can be heated evenly in hot oil to make it expand slowly, and it is not allowed to directly heat with an open flame.
Avoid butter smearing
(1) Apply grease to the drill cylinder pad. Butter is a commonly used grease in the repair of long spiral drills and can act as a lubricant and seal. Therefore, some repairmen apply a layer of butter to the cylinder pad when installing the cylinder pad, which is believed to increase the tightness of the diesel engine. As everyone knows, this will affect the performance of the diesel engine. The cylinder head gasket is the most important seal between the diesel engine cylinder block and the cylinder head. It not only seals the high temperature and high pressure gas generated in the cylinder, but also seals the cooling water and lubricant oil in the cylinder head and cylinder. When disassembling the cylinder head gasket, pay special attention to its sealing quality. If the cylinder pad is greased during installation, when the cylinder head bolts are tightened, some of the butter will be squeezed into the cylinder water channel and the oil channel. When the grease left between the cylinder pads is working in the cylinder, due to the influence of high temperature, part of the grease will flow. The human cylinder burns, and the other part remains on the joint surface between the cylinder block and the cylinder head, which creates a gap between the cylinder pad, the cylinder head and the plane of the machine body. The high temperature and high pressure gas can easily impact the cylinder pad from this and damage the cylinder pad, causing leakage. gas. In addition, the butter will produce carbon deposits at high temperatures for a long time, resulting in premature aging and deterioration of the cylinder mat. Therefore, do not apply butter when installing the cylinder head gasket.
(2) Apply butter to tire nuts. In order to easily tighten the nut and prevent corrosion, many repairmen apply oil to the bolts and nuts of the tire. This is actually a wrong practice. Because the tire nut is tightened, there is a self-locking feature between the threads. This is because the thread helix angle is smaller than the equivalent friction angle between the threads. For a given bolt connection, the helix angle is a certain value, and the equivalent friction angle varies with the friction between the threads. Obviously, after the oil coating, the equivalent friction angle between the threads is reduced, and the self-locking performance of the bolt connection is deteriorated. Therefore, never apply grease or dripping lubricant to the bolts and nuts of the tire. Doing so will make the nut loose and even cause an accident.
Avoid bolts tighten too tightly
In the process of disassembly and assembly of long spiral pile drivers, bolts in many parts are required by the specified torque, such as transmission boxes, cylinder heads, hubs, connecting rods, and front axles. Tightening torques are specified in the manual. Must not change at will. However, many users mistakenly believe that tightening some of them will be more secure, but tightening them too tightly will cause the screws or bolts to break, and it may also cause malfunctions due to thread sliding.
Avoid tire pressure is too high
The tire inflation pressure of Henan Sanli mechanical wheeled auger is an important factor in determining its service life and work efficiency. Tyre pressure is too high or too low will affect its service life, but also not conducive to safe driving, especially in hot summer. The scientific inflation standard should be: based on the standard tire pressure, with the temperature changes, the tire pressure slightly adjusted. For example, in summer, it should be 5%-7% lower than in winter. Taking into account the high temperature in summer, the gas is heated and the pressure is increased. Instead, the winter temperature must reach the standard pressure or be slightly lower.
Avoid cylinder gap measurement is not allowed
When measuring the cylinder gap, hydraulic drills in particular cannot be measured in the direction perpendicular to the piston pin bore of the piston skirt and are measured in other directions. The structural characteristics of the aluminum alloy piston is that it is small and large, it is a cone, and the skirt section is oval, so the cylinder gap along the circumferential direction is not equal. When measuring, it is specified that the clearance in the direction of the long axis of the ellipse shall prevail, that is, the clearance of the piston skirt perpendicular to the direction of the piston pin hole shall be measured. This measurement is more convenient and accurate, and in the reciprocating motion, the direction of the piston skirt perpendicular to the pin hole of the piston is greatly abraded due to the effect of lateral pressure. Therefore, when measuring the cylinder gap, the piston skirt should be perpendicular to the piston. Pin hole direction measurement.
Avoid grinding the bearing bush with emery cloth
For some inexperienced repairers, scraping is a difficult task. Since the scraping technique is difficult to grasp, the bearing is not easy to meet the technical requirements. For this reason, when replacing the bearing, it is necessary to increase the bearing. The contact area of ​​the crankshaft is sanded instead of the trowel. This method is extremely undesirable in practical maintenance because the abrasive grains on the abrasive cloth are hard and the bearing alloy is soft, so that the sand grains are easily embedded in the alloy when the grinding is performed, and the journal wear is accelerated when the diesel engine is in operation. Reduce the service life of the crankshaft
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