【Mechanical Equipment Technology Edition】Daily Question 201802024: Common Faults in Refrigeration Systems (9.6)
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This post was last edited by YORK Industrial Refrigeration on 2018-2-26 at 08:13. Starting from now, in order to enhance communication among users, a 【Daily Question】 activity has been launched on the Mechanical Equipment Technology forum. We hope everyone will participate actively to progress and improve together! ! ! Rewards: 3 wealth points for active participation, 10-15 wealth points for correct answers. This question is valid for two days; no score will be given after that period. If the screw of a screw compressor suffers damage due to dead spots, how should it be repaired depending on the severity of the damage? For the answer, please see: https://bbs.hcbbs.com/thread-1930554-1-1.html ============================== High-quality promotions: Mechanical equipment——Maintenance procedures for York screw compressors https://bbs.hcbbs.com/thread-1806833-1-1.html Mechanical equipment——Upgrading of York Quinton control centers https://bbs.hcbbs.com/thread-1804837-1-1.html Mechanical equipment——Major repairs for GEA Grasso screw compressors https://bbs.hcbbs.com/thread-1800467-1-1.html Mechanical equipment——Disassembly and maintenance of British HOWDEN screw compressors https://bbs.hcbbs.com/thread-1832529-1-1.html Mechanical equipment——Disassembly and maintenance of Japanese Maekawa MYCOM screw compressors https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=
Gently polish off the damaged peaks with an emery stone; in more severe cases, use laser coating
Mild cases can be polished with a laser, while severe cases require welding repairs and re-machining
The screws of screw air compressors require special cutting tools to be machined on expensive dedicated equipment, as the tooth surfaces of the rotor are spatial curves; in addition, high precision is also demanded for the machining of the compressor cylinders.
Contact the manufacturer to confirm the dead center, pull out the dead center, and redo the dynamic balancing.
If it’s light, grind it; if it’s heavy, that’s even better
The screws of screw air compressors require special cutting tools to be machined on expensive dedicated equipment, as the tooth surfaces of the rotor are spatial curves; in addition, high precision is also demanded for the machining of the compressor cylinders.
1. The threaded surface of the worn screw, whose diameter has decreased, is treated, followed by thermal spraying with a wear-resistant alloy, and then ground to the desired size. 2. Weld a wear-resistant alloy onto the threaded part of the worn screw. Depending on the degree of wear of the screw, a wear-resistant alloy with a thickness of 1–2 mm is welded on; this alloy is composed of materials such as C, Cr, Vi, Co, W, and B, which enhances the screw’s resistance to wear and corrosion. The screw is then ground to the desired dimensions. 3. The screw can also be repaired by coating its surface with hard chromium; chromium is a metal that is resistant to wear and corrosion, but the hard chromium layer tends to peel off easily.
The screws of screw air compressors require special cutting tools to be machined on expensive dedicated equipment, as the tooth surfaces of the rotor are spatial curves; in addition, high precision is also demanded for the machining of the compressor cylinders.
Gently polish off the damaged peaks with an emery stone; in more severe cases, use laser coating
The profile and meshing clearance of the two rotors, as well as the radial clearance between the rotors and the casing and the end-face clearance between the rotors and the casing, are the main factors affecting the performance and efficiency of the compressor. For every 50% increase in these relative clearances, the efficiency decreases by approximately 5%. Therefore, when dead spots occur, repairs must be carried out according to the specific circumstances: 1. When the degree of damage to the rotor’s tooth profile is no more than one-fifth, the comparison method or the gap method can be used to repair the tooth profile; depending on the conditions on site, grinding and coating can be employed to restore the proper shape and gap in those areas. 2. When the damage is severe enough to exceed the limits of on-site repair, it is necessary to return the component to the factory for professional welding, machining to restore the shape and clearance, as well as balancing to ensure proper operation.