How to reduce the damage rate of nylon rods on couplings
Thread Content
This post was last edited by shuimufeng111 on 2019-7-17 at 19:55. In this type of pin coupling, the shaft sleeve and one side of the coupling are secured together using 12 nylon pin rods (located at the red circles in the diagram); in total, there are 24 such pins on each side. Currently, nylon pin shafts often get squeezed and deformed, resulting in damage. Is there any way to improve the coupling in order to reduce wear on the pin shafts? Later, according to feedback from the workshop, the temperature of this coupling was very high, and water had to be used to cool it down; the reason for such high temperatures is unknown. It might be the hot air blown by the motor, or the heat from the motor being transmitted through the shaft. To withstand high temperatures, I planned to use a diaphragm coupling, but the equipment manufacturer advised against it and suggested using a new pin coupling instead!
The measurement of the fit clearance and the requirements for concentricity need to be higher
This post was last edited by shuimufeng111 on 2019-7-16 at 13:32. What kind of fit should be used for nylon pins and bushings?
This coupling has a simple structure and is easy to manufacture; it is convenient to install, remove, and replace its elastic elements. The use of nylon provides a slight degree of compensation for axis misalignment. However, the elastic elements are subjected to shear forces during operation, resulting in very poor reliability. It is only suitable for medium and low-speed drive systems with low reliability requirements, and not appropriate for applications that demand higher levels of operational reliability. In situations where the speed is too high or the power is too great, it is recommended to use a flexible double-diaphragm coupling or a permanent magnet coupling, in order to prevent such accidents from occurring in the first place.
Thank you. The nylon pins used in our factory are made of PA6; according to the standard GB/T 5015-2017 for elastic pin toothed couplings, it should be MC nylon. Moreover, the factory uses water to cool the coupling (1450 revolutions per minute). PA6 has a high water absorption capacity, which can lead to a significant decrease in strength. I’d like to try replacing it with MC nylon first; if that doesn’t work, I’ll follow your advice and switch to a diaphragm coupling. I can’t figure out how abnormally high temperatures can occur to the point where cooling with water is necessary.
Our factory also has such couplings, but they consist of a steel rod and a nylon rod that are arranged crosswise
Can I use a steel rod? Won’t it vibrate?
High temperature indicates the presence of displacement friction. It still seems to be due to a large error in alignment. Were any marks made during disassembly? Sometimes this slot has a direction, and it’s important to install it in its original position.
1. The alignment was corrected before; it didn’t deform for a short time, but then it started to deform frequently again after some time. The coupling has its end caps opened daily to check the condition of the nylon pins. I don’t quite understand how friction and heat can be generated by displacement, since both halves of the coupling are fixed together. 2. No markings were made during disassembly; can replacing it with a new coupling of the same model solve the problem of constant alignment errors?