WY20 hydraulic excavator hydraulic pump suction pressure fluctuation reason

Below, the situation of the working face of the eccentric sleeve should be under the action of the broken object, and the working surface of the eccentric circle through the movable cone shaft is on the round surface above and below the thick edge.

Due to structural reasons, the eccentric sleeve is designed to be inverted. Therefore, during normal operation, the weight of the entire eccentric sleeve is supported by the bottom surface of the large gear, and the bottom surface of the large gear has relative motion traces in the entire area.

After analysis and comparison, it can be considered that the coarse crusher eccentric sleeve is not running in the vertical state in the face frame seat hole, but has an inclined angle, and the tilt direction is the thick edge of the upper end of the eccentric sleeve is inclined to the thin edge direction. The reason for this inclination may be that the tolerance of the machining position tolerance of the eccentric sleeve or the large gear joint surface is too large; 1 the assembly quality does not meet the requirements, because the eccentric sleeve is operated within the rack sleeve at an inclined state, so the parts of each operation The stress condition also undergoes a major change from the original surface contact to a point contact, the working surface that is not easy to form an oil film will not be reliably lubricated, and the gradually elevated working temperature will be the rack copper sleeve eccentric sleeve. And the copper bushes inside the copper sleeves in the eccentric sleeve are burned until they are locked.

2 Detection of Eccentric Sleeve and Large Gear Coupling Position After detecting the assembly between the eccentric sleeve and the large gear, it was found that the dimensional error of the assembly is large. The specific situation is that the circumferential depth of the lower end of the eccentric sleeve and the bottom surface of the large gear is different. And symmetry. The depth of the edge of the bevel measured directly below the thick edge of the eccentric sleeve is 7.68, and the depth of the edge of the bevel is measured to be 7.10 directly below the edge of the bevel. When the feeler is inspected, the eccentric sleeve and the gear assembly face the step In the case of combination, it was found that the interval of the week is not equal, the gap directly below the thick edge of the eccentric sleeve is 2.3, and the gap directly below the thin edge is 1.7. By comparing the detection data, it is found that the dimensional change of the upper and lower positions is corresponding and consistent. The change value is about 0.6, and the law of change is from big to small and then from small to large.

In the progressive disintegration test, it was found that the tilt of the eccentric sleeve was caused by improper assembly. After confirming the cause of the fault, when the new eccentric sleeve is replaced, the assembly of the eccentric sleeve and the large gear is ensured slightly, and the three machines after the repair are basically in the normal state of production and operation. However, on the oil return screen of the lubrication system, foam and lead, silver and gold chips can still be recovered. In order to prolong the service life of various parts, such as the levelness of the lower frame body and the levelness of the eccentric sleeve bottom thrust bearing, etc., there is still room for improvement in inspection or adjustment. Reversible hammer mill hammer repair old waste Hou Yulong Ping, Shan coking company Henan 467021 reverse hammer mill 6171430 father 1300 is commonly used in large and medium-sized coking plant crushing machinery, with good effect and strong adaptability , Our company uses the crushing process for clean coal. However, the hammer wear in use needs to be changed frequently, and then whether the scrapped hammerhead can be reused.

Work face, easy to wear during use, especially in 6 places. When the wear on the face is serious and can't be used, install it in reverse and use 5 sides. When the wear on the face is serious, especially at the place where it cannot be used, the hammer is basically scrapped. We have restructured this so that the severely worn joints will be cut off from the benefits, beveled, and forged joints of the same size can be welded.

Using a new hammerhead, the average life span is one and a half months to a month, and each set of hammers has a minimum of 14,000 yuan per set of 70, each at least 200 yuan, and an annual consumption of 168,000 yuan. For the reuse of the scrapped hammer head, the effect is good and the service life is quite long. The rebuilding of each hammerhead is only 4900 yuan and only 70 yuan per hammerhead. In the next year, it can save 109,200 yuan. Excavator 20 hydraulic excavator Hydraulic Pump suction port pressure fluctuation causes I Luoming Quantuo Group Technology Center Engineering Institute, Henan Luoyang 471039 1 company developed a hydraulic excavator hydraulic system using a constant power transformer ram 1 series, in order to ensure the pump Suction capacity, using a closed inflatable pressurized fuel tank. When measuring the inlet pressure of the children's hydraulic pump, it was found that the pressure changes periodically with the movement of the working device, and the range of change is large, the minimum is 0.075MPa, the vacuum is 0.025, and the highest is 0.2, 3. The working device When not exercising, the pressure is about 0,4 MPa compared with Deding. 1 We know that if the pressure in the oil suction port of the oil pump is too low, that is, the vacuum level exceeds the limit, the working efficiency of the pump will be reduced, and cavitation will easily occur. The fluidity of the oil will deteriorate and the surface of the component will be subject to localized erosion, fatigue and even damage. Sound and movement.

Therefore, the suction pressure of the oil pump should not be too low, and the suction pressure of the general plunger pump should not be lower than 0.085; while the pressure of the suction port is too large, that is to say the pressure in the oil tank is too high, which will cause the hydraulic pump and the motor casing. The pressure of the drain inside the body increases, which can seriously affect the normal operation of the hydraulic pump and the hydraulic motor, and even cause the shaft seal to break down and fail to work. The case drain pressure of the plunger pump and the plunger motor does not exceed 0.15 MPa. Therefore, the hydraulic pump suction port pressure is too high or too low will affect the speed of the hydraulic system to work properly, and even the Hydraulic Components are destroyed. Reasons to eliminate in time.

1Cause Analysis The hydraulic pressure of the hydraulic tank is 0.15 MPa, which is achieved through the air pressure system. The gas is provided by the air compressor on the engine, after the decompression of the storage tank, and the pipeline is sent to the fuel tank. Internally, the tank pressure is increased, and the oil pump suction port pressure 3 working device is driven by a double-acting single-piston rod Hydraulic Cylinder. Due to the difference in area between the two working chambers of the cylinder, the rod cavity area difference is always smaller than that of the rodless cavity. The area, when the cylinder moves, there is a difference between the flow of the two chambers into and out of the child. If the big cavity of the oil tank is filled with oil, that is, the oil pump supplies oil to the large cavity, then the small cavity flows out so that the oil flow from the oil tank is greater than the oil flow from the oil tank back to the tank. Then the oil boy in the tank will When the oil level is reduced, the oil flow in the oil tank will be greater than the flow rate into the tank. The pressure in the tank will decrease. The larger the difference, the lower the pressure will be, resulting in an oil pump. Inlet pressure is too low.

When the small cavity of the oil cylinder enters the oil, that is, the oil pump supplies oil to the small cavity, the oil flowing out of the large cavity enters the oil tank. Since the oil flow entering the small cavity is smaller than the flow of the large cavity, the oil pump sucks the oil from the oil tank. The fluid flow is set to be less than the flow of oil flowing from the large chamber of the cylinder to the tank. Then the oil level in the tank will increase, the oil level will increase, the gas in the tank will be compressed by the pressure, the safety valve will open, and the gas in the tank Drain to keep the pressure constant. If the flow of exhaust gas is less than the flow of children in the tank, the pressure in the tank will increase, causing the pressure in the oil pump inlet to increase.

Taking the stick operation as an example, it can be calculated that when the stick cylinder is in motion, the value of the flow of fluid in and out of the two-chamber fluid in the fuel tank is increased or the saltiness of the fluid in the fuel tank is relatively large. When the flow of gas out of the tank reaches this value, the pressure in the tank can not be guaranteed. Due to the limitation of the air source, and the long lengthy bending of the air pressure line and the small diameter of the air pipe, resulting in a large air resistance, this is the main reason for the insufficient intake air volume, 170,. When the working device does not move, ie the cylinder does not move, the oil discharged from the oil pump directly flows back to the oil tank. That is to say, the flow of the oil sucked from the oil tank by the oil pump is equal to the flow of oil flowing back to the tank, so the oil tank The oil level is constant, the oil level is constant, and the pressure is stable, so that the oil pump inlet pressure remains unchanged.

In addition, the oil pump suction pipe is too long and bends, which increases the resistance to oil absorption. It is the reason why the oil pump inlet pressure is too low.

Improve the airway system to increase the diameter of the air pressure pipeline, reduce the bending, increase the air supply child, and replace the larger safety valve. However, this method has changed a lot, and is limited by the arrangement of pneumatic piping, and the cost is also high.

Remove the air line pressurizing system. Install a pre-pressure air filter model on the fuel tank. Model number is 10.020.4510. It can ensure that when the internal pressure of the fuel tank is less than 0.1MPa, the check valve is opened. When the pressure in the tank is greater than io, 12MPa, the internal exhaust check valve opens and the gas is exhausted. Ventilation up to 4501 heart is far greater than the flow difference between the two chambers of the oil in and out of the cylinder. At the same time, shorten the oil pump suction pipe to reduce the bending of the oil pipe. This will ensure that the suction pressure of the oil pump is within the normal range of 0.0.12 MPa. This method is simple and inexpensive, and eliminates the tank's pressurized system, which reduces costs.

After the improvement of the first method, the machine has a good effect. The reasons for the collision between the cylinder and the drive and selenium are only relevant. Zhou Jiqin, Jinchang, Gansu 737102, USA The introduction of underground mining equipment, said 0922, scraper, small power and comfortable operation, its fully hydraulic closed brake, etc. More suitable for gold mine working environment. However, when the machine was operating downhole, it had successively tipped over and dumped the cylinder in a six-year period. The direct cause of the accident is that the tipping cylinder collided with the drive axle housing and squeezed to make the housing of the cylinder recessed and cracked, while the connection between other components and components was not obviously damaged, but the tilting cylinder and the rocker arm, the rocker arm and the connecting rod The angle between the two is different from the normal position.

19220 Scraper Working Mechanism Analysis DC, EFHM Lifting Cylinder for Turning Rocker Arm! The lift-lifting-link-barrel-bucket boom mechanism includes a lift arm 2 and two lift cylinders 6. The dump mechanism is composed of a tilting cylinder 5, a rocker arm 4, a connecting rod 3, and a bucket 1. Two parts constitute a parallel link mechanism. With this mechanism, when the lift arm is raised and lowered, the bucket position is maintained in translation to ensure that the scooped material will not fall due to the tilt of the bucket, which greatly simplifies the operation. The revolving bucket adopts a reversing single-link type tipping bucket mechanism. This linking mechanism is a six-bar linkage consisting of two rod mechanisms, and the rocker arm steering is opposite to the bucket. 9220 scraper tipping mechanism and some imported scrapers such as Germany's 4. France's 5003 squeezing, WesComtech, condition, squeak, and ram linkage arm and bucket connection 3 such that the cylinder without rod cavity into the oil The piston rod extends, causing the bucket to turn. Because the piston's force-free area is larger than the rod cavity, the tilting cylinder has a low speed and a large output. Fully match the working status of the bucket.

On the contrary, there is a rod chamber for oil, the piston rod is recovered;

The thrust of the cylinder is fully utilized. Due to the configuration of the rocker linkage system, the stroke of the piston rod is short, and therefore the tilt cylinder is relatively short and well-arranged. The position of the cylinder rod after it sticks out is far away from the bucket, so it is hidden and it is not easy to be injured by scattered ore.

Due to the adoption of the inverted six-bar mechanism, the structure of the working mechanism is very compact, the distance between the center of gravity of the front suspension small working mechanism and the center of gravity of the vehicle is good, and the operator's field of vision is good.3 However, the distance between the lowest position of the tipping cylinder and the front drive axle is relatively small. Under the influence of abnormal factors, it is easy to ask questions. This is because the position of the lifting mechanism will affect the driver's line of sight; lowering the position of the transaxle will reduce the ground clearance of the vehicle.

Downhole trackless equipment features a compact structure.

2 Analysis of Damage Caused by the Cylinders The 9220 working mechanism has two extreme positions up and down, that is, shoveling conditions and unloading conditions.

2.1 Scoop condition analysis When the scraper is in the scooping condition, the boom is lowered, the bucket is placed on the ground, the tip of the bucket touches the ground, the bucket is inserted into the pile by means of the machine thrust, the scraper moves forward while turning the bucket, shovel Take the material. When the boom falls to the lowest level and the bucket mouth is turned to level, the tilting cylinder position is the lowest and the distance from the front drive axle is the shortest. 2. After actual measurement, the tilt is 4, DC irrigation, cylinder, 1 rocker arm EF rod only The bucket HM lift cylinder and; lift arm around 2 Hutu conditions, working mechanism and component location tipping cylinder and drive axle still have a certain distance, in order to ensure the safety of the cylinder. Therefore, under normal conditions, the bucket block is normal, and the clearances of the hinge points are appropriate. The various components of the working mechanism of the Hu Yun machine will not interfere with the drive axle.

2.2 Unloading condition analysis When the scraper is unloaded, the lifting boom raises the bucket to the unloading position and the inverting bucket unloads to the mine car or the irrigation well. From 3, it can be seen that when the lift arm is raised to the maximum, the bucket EF connecting rod is lifted by the Shanghai bucket lift cylinder 4, and the 2 working conditions and position of the working mechanism and components are turned to the limit position. The block is in contact with the lift arm. At this time, the connecting rod and the rocker arm have the largest angle. In this case, if the connecting point of the rocker arm and the connecting rod is subjected to an external force 4, or the limit block does not exceed the limit, the clearance of each hinge point is too large, so that the rocker arm and the connecting rod are between Incline angle 1