Reasons and repair methods of screw damage of screw chiller

Reasons and repair methods of screw damage of screw chiller

Screw chillers are named after the use of screw compressors. They are often used in large-scale industrial refrigeration such as chemical plants and central air-conditioning systems. Because the performance of screw chillers is more stable and efficient, they are welcomed by many users. During the use of the chiller, some damage is unavoidable. The following editor will introduce the reasons for the damage of the screw of the screw chiller.

　　 1. The screw of the screw chiller rotates in the barrel, and the lubricating oil and compressed gas rub against the screw and the body, causing the working surface of the screw to gradually wear. The matching diameter gap between the screw and the body will increase a little as the two gradually wear. However, since the resistance of the head and the manifold on the front of the machine body has not changed, this increases the leakage flow of the squeezed air forward and reduces the flow rate of the discharge machine.

　　 2. If there are corrosive substances such as acid in the gas, it will accelerate the wear of the screw and body of the screw chiller.

　 　　3. When the machine wears abrasives or metal foreign matter is mixed into the material, the screw torque is suddenly increased. This torque exceeds the strength limit of the screw, causing the screw to twist.

　　 When the screw of the screw chiller is damaged, if the damage is not repaired, the screw compressor will be unusable and the machine unusable. If the screw is damaged, it is expensive to replace the compressor, so in general, customers will choose to repair the screw.

　　1. The twisted screw should be considered according to the actual inner diameter of the body, and the outer diameter deviation of the new screw should be given according to the normal clearance of the body.

　　2. After the surface of the thread with the reduced diameter of the worn screw is treated, it is thermally sprayed with a wear-resistant alloy, and then processed to size by grinding. This method is generally processed and repaired by a professional spraying factory, and the cost is relatively low.

　　3. Wear-resistant alloy is built-up on the threaded part of the worn screw. According to the degree of screw wear, the wear-resistant alloy with a thickness of 1-2mm is surfacing welded. This wear-resistant alloy is composed of materials such as C, Cr, Vi, Co, W, and B to increase the wear resistance and corrosion resistance of the screw. Grind the screw to size. Due to the high cost of this kind of processing, it is rarely used except for special screws.

　　4. Hard chrome plating can also be used to repair the screw. Chromium is also a wear-resistant and corrosion-resistant metal, but the hard chrome layer is easier to fall off.

　　 The screw of the screw chiller has been repaired, and the body must be repaired. Since the inner surface of the body is harder than the screw, it will be damaged faster than the screw. The scrap of the body is the increase in the inner diameter due to time wear. The repair method of the compressor body is if there is a certain nitriding layer, the holes in the body can be directly bored, ground to a new diameter size, and then a new screw can be prepared according to this diameter.