In the process of mine construction and production, md mining wear-resistant centrifugal water pumps are responsible for the important task of drainage. Correct use and dimensional water pumps play a decisive role in the safe production of mines. This article mainly analyzes the inspection and repair of the main parts and wearing parts of the wear-resistant mining centrifugal water pump, and puts forward a series of effective measures for operation and maintenance.
Malfunctions and judgments of wear-resistant centrifugal water pumps for md mines
1) The main characteristics of the operation failure are: the pump does not absorb water, the pointer of the pressure gauge and the vacuum gauge vibrates violently; the pump does not discharge water, and the value of the vacuum gauge is too high; the pump casing is not full of water before starting, etc.
2) The characteristic features of performance failures mainly include: too much starting load, too much operating current, pressure gauge indicating but no water from the drain pipe, insufficient flow, etc.
3) The main characteristics of mechanical failure are: bearing overheating, stuffing box overheating and excessive water leakage in the shaft seal; when the rotation speed of the water pump rotor gradually increases and approaches the natural frequency of the water pump, the water pump will vibrate violently, making it difficult to work normally Even cause structural damage.
Inspection and repair of main parts and components of md mine wear-resistant centrifugal water pump
1) Repair of impeller. The impeller is rubbed with other parts, and the partial wear caused by it can be repaired by surfacing welding. The layer thickness of the impeller is reduced, and the cast iron impeller has pores or slag inclusions and cracks. Generally, it is replaced with new spare parts or repaired by "repair welding".
The radial runout of the outer circle of the inlet and outlet ends of the impeller should generally not exceed 0.05mm. If it is not too much (within 0.1mm), go to 0.06~0.1mm; if it is too much, check the straightness deviation of the pump shaft, straighten the pump shaft, and eliminate the radial runout of the impeller.
2) Repair of bushings. The wear amount is very small, and the method of surfacing welding is used to repair it. If the wear is serious and the wear scar is deeper, you should replace the bushing with a new one.
3) Repair of the pump shaft. After the bending direction and bending of the pump shaft are measured, the pump shaft can be straightened. When the wear depth is not too large, use surfacing welding to repair. After surfacing welding, it is turned to the original size on a lathe. When the wear depth is large, it can be repaired by the "inlaid and added parts method". Pump shafts with severe wear or cracks are generally not repaired and replaced with spare parts. If the side of the keyway on the pump shaft is slightly damaged, it can be repaired with a file; if the skew is severe, it should be repaired by surfacing. In addition, it can also be repaired by changing the position of the keyway.
4) Repair of the pump body. When the inner circle size of the rolling bearing hole of the pump body is worn out or there are defects such as steps or grooves, the bearing hole size is bored, and then the bearing hole size is inserted according to the boring bearing hole size. When the cast iron pump body has slag inclusions or pores, and the pump body cracks due to vibration, collision or knock, repair welding or bonding methods.
Detection and maintenance of common wearing parts of md mine wear-resistant centrifugal water pump
Sealing ring inspection and measurement
1) Check the wear of the seal ring. The wear of the seal ring usually has two types: uniform wear in the circumferential direction and partial partial wear. The wear of any kind of radial clearance will cause the seal ring to be scrapped.
2) Measurement of the radial gap between the seal ring and the outer circle of the inlet end of the impeller. Vernier calipers can be used to measure the radial clearance between the seal ring and the inlet end of the impeller. First measure the size of the inner diameter of the seal ring, then measure the size of the outer diameter of the impeller inlet end, and then calculate the radial gap between them for comparison. If the limit gap value is reached, a new sealing ring should be replaced. As for the axial gap between the seal ring and the impeller, the requirements are generally not high. It is better to have a gap between the two without friction.
Repair of sealing ring
There should not be any looseness after the outer circle of the sealing ring and the inner hole of the pump cover are matched. The outer diameter of the seal ring is the repair size, which can be filed, and its interference value is about 0~0.02mm. Then, hit the sealing ring into the hole in the center of the pump cover with a hand hammer. A clearance fit is formed between the inner circle of the sealing ring and the outer circle of the inlet end of the impeller. If the gap is too small, you can make the car bigger or scrape bigger to keep a certain radial gap between the two. If the gap is too large, a new seal ring should be replaced. The thickness of the sealing ring is small and the strength is low. If there is a large wear or fracture, it is usually not repaired, but should be replaced with new spare parts.
Packing seal installation and repair
1. Inspection and measurement of packing seal
The main parts of packing seal include stuffing box shell, packing, liquid seal ring, packing gland, bottom bushing, etc. When inspecting and measuring the packing seal, focus on the following aspects:
1) The radial clearance between the pump casing and the shaft sleeve. First use a vernier caliper to measure the inner diameter of the center hole, and then measure the outer diameter of the sleeve, and then calculate it. The smaller the value of the radial clearance a, the better, but there should be no friction. When the radial clearance is too large, the phenomenon of "eating stuffing" appears. The radial clearance between the pump casing and the shaft sleeve is 0.3~0.5mm.
2) The radial clearance between the outer circle of the packing gland and the inner circle of the stuffing box.
The stuffing box of the centrifugal pump plays a guiding role in the advancement of the packing gland. If the radial clearance is too large, the packing gland is easily crushed, which will cause friction and wear.
3) The radial gap between the inner circle of the packing gland and the outer circle of the shaft sleeve. The radial clearance value between the inner circle of the packing gland of the centrifugal pump and the outer circle of the shaft sleeve is too small, and the inner circle of the packing gland and the outer circle of the shaft sleeve will rub, and frictional heat will be generated at the same time, which will cause the packing to coking and fail, and make the packing The gland and shaft sleeve are worn out. Generally, the radial clearance is 0.4~0.5mm.
2. Repair of packing seal device
1) Packing gland repair The radial gap between the outer circle of the packing gland and the inner circle of the stuffing box is 0.1~0.2mm. If the radial clearance is too small, it can be turned or filed to the required size. If the radial clearance is too large, a new packing gland should be replaced. The radial gap between the inner circle of the packing gland and the outer circle of the shaft sleeve is 0.4~0.5mm. If the gap value is too small, make the inner hole of the packing gland larger on the lathe to ensure the due gap.
2) Repair of packing seal device. The mechanical seal of the centrifugal pump is realized by a moving ring mounted on the pump shaft and a static ring fixed on the inner circle of the stuffing box. The end faces of the two rings are tightly attached to each other by the elastic force of the spring and the pressure of the medium to play a sealing role.
