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What Are The Specific Operation Methods For Maintenance And Repair Of Screw Compressors In Cold Storage?

Mar 23, 2020

What are the specific operation methods for maintenance and repair of screw compressors in cold storage?


I. Disassembly method of cold storage screw compressor


Before the cold storage screw compressor must be overhauled, if possible, unload the slide valve to the "0" position, shut down normally, and cut off the power. The compressor can be disassembled only after the pipeline connected to the compressor is cut off and the refrigerant and lubricant in the compressor are discharged. Pay attention to good habits when disassembling, and place parts of different parts separately, and make necessary assembly marks.


1. After removing the pipes, couplings and anchor bolts connected to the compressor, lift the compressor to the workplace. There are operating platforms.


2. Remove the suction filter and suction check valve.


3. Remove the energy indicator.


4. Remove the positioning pin, remove the suction end cover in parallel, and take out the oil piston and balance piston. Note that the positioning pin can only be pulled out and not smashed out. Be sure to remove the positioning pin first, and then remove all the bolts, to prevent the weight of the suction end cover from acting on the positioning pin and bending the positioning pin.


5. Remove the shaft seal cover and take out the shaft seal. Be careful not to hit the moving or static ring.


6. Remove the positioning pin and remove the exhaust end cap.


7. Remove the bearing gland, lock nut, washer, thrust bearing, adjustment pad, etc. To remove the lock nut, use the special tools provided and first open the lock sheet of the lock washer. Mark them at any time and place them separately.


8. After removing the positioning pin, remove the exhaust end seat.


9. Take out the active rotor slowly and smoothly by using special eye bolts, and do not collide with the body. At this time, the driven rotor rotates with it.


10. Take out the driven rotor.


11. Take out the slide valve.


Second, the inspection items of cold storage screw compressor


1. Check the inner surface of the machine body and the surface of the slide valve for abnormal wear marks, and measure the inner surface size and roundness with an internal dial indicator.


2. Check whether there are any wear marks on the end faces of the main and driven rotors and the suction and exhaust end seats.


3. Check the wear and tear of the outer diameter and tooth surface of the main and driven rotors, and measure the outer diameter of the rotor with an external dial indicator.


4. Measure the main shaft diameter of the rotor and the inner diameter of the main bearing hole to check the main bearing wear.


5, check the wear of the shaft seal.


6. Check the deformation and damage of all "o" rings and springs.


7. Check all internal oil circuits of the compressor.


8. Check the energy indicator for damage or jamming.


9. Check the oil piston and balance piston for abnormal wear.


10. Check whether the transmission core or diaphragm of the coupling is damaged.


Ⅲ. Repair method of screw compressor in cold storage


After inspection, repair or replace damaged parts. The details are as follows:


1. For less serious abrasion and hair pulling phenomenon, the fitter can grind and smooth with oil stone. The surface of the rotor journal and the shaft seal's dynamic and static rings must not have any defects such as rust, cracks, etc. After the surface of the main journal is polished, its size should be carefully measured, and the main bearing should be adjusted based on this.


2. If the main bearing is severely worn and exceeds the limit of clearance with the shaft, it should be replaced. If the bearing alloy is cast, the coaxiality between the inner surface and the bearing hole must be guaranteed.


3. Thrust bearing is damaged or the clearance is increased, it must be replaced with a new one. And should measure its vacuum clearance size, based on this with the bearing adjustment pad.


4. All gaskets and "O" rings must be replaced if damaged. The gasket can be machined by yourself, but be careful not to break or crack near the bolt hole to avoid leakage. The gasket should be made of high-quality materials. The "O" ring should be made of a material suitable for the refrigerant.


5. Clean the sealant on both sides of the body and the plane of the suction and exhaust end seat. Be careful not to scratch the surface.


Four, assembly details of the cold storage screw compressor


After inspecting each part and repairing or replacing damaged parts, assembly work can be performed. When assembling, pay attention to the marks marked during disassembly, and do not confuse the parts. When assembling, it is necessary to measure the assembling gap of each part at any time, and to adjust the gap or replace the parts where the gap exceeds the standard. See clearance table for assembly clearance


1. Clean all parts and blow dry with compressed air.


2. Prepare all necessary tools and clean them.


3. Install the main bearing into the bearing hole in the original position, and measure the inner diameter of the bearing so that the inner diameter meets the clearance requirements for matching with the rotor journal.


4. Apply sealant evenly on the mating surface of the suction end seat and the body.


5. Place the suction end seat on the suction end of the body, and string some bolts to bear the weight. After pressing in the positioning pin, tighten the bolt.


6. Install the slide valve and its guide plate. The guide plate can be fixed with bolts after positioning with positioning pins.


7. Apply the same type of lubricating oil to the main bearing hole and the hole in the body of the suction end as they are used during operation, and put them into the male and female rotors. The rear-mounted rotor should be slowly rotated in, and it should not be forced into the body.


8. Close the female and male rotors on the suction end seat, and measure the size difference between the rotor exhaust end face and the body exhaust end face.


9. Apply sealant evenly on the joint surface of the exhaust end seat and the body.


10. Place the exhaust end seat on the exhaust end of the body, press the positioning pin, and tighten the bolt. When installing the exhaust end seat, pay attention to the inner bore of the main bearing, and do not damage the main bearing.


11. Install the adjusting washer and thrust bearing, and fix the inner ring of the thrust bearing on the journal of the rotor with a round nut and an anti-loosening lock pad. The thrust bearings are installed in pairs, paying attention to the installation direction.


12. Install the rotor bearing gland and press the outer ring of the thrust bearing against the body. Remove the connection bolt between the exhaust end seat and the body, and pull the exhaust end seat together with the rotor, and measure the gap between the exhaust end face of the rotor and the exhaust end seat. This gap is the exhaust end gap. If the gap is not reasonable, the thickness of the adjustment pad should be changed. Adjust after adjusting the clearance of the exhaust end. After installation, move the active rotor according to the actual operation of the steering wheel. The rotation should be flexible without jamming.


13. Install the positioning cap on the exhaust end cap, and fix it with bolts.


14. Install the shaft seal moving ring, and apply freezing oil on the surface of the moving ring and the rubber ring.


15. Install the static ring into the shaft seal gland, and fix it on the exhaust end seat with bolts. Adjust the preload of the shaft seal spring by the thickness of the gasket. The static ring surface and the static ring rubber ring are also coated with freezing oil.


16. Install oil piston and balance piston. Apply freezing oil during assembly.


17. Install the positioning pin on the suction end seat and fix it with bolts.


18. Install the energy indicator. Note that the pointer corresponds to the position of the slide valve.


19. Install the repaired suction filter and check valve on the suction end seat. Ship the assembled compressor to the unit. After finding the coaxiality, fix the compressor and motor and connect them with a coupling.