To Increase Wear Resistance of Screw Cylindrical Compression Springs Working with Coil Contacts

During operation of springs, especially cyclic buffer and high-speed springs, there are inevitable relative movements of their surfaces, friction, and coil contacts. Due to friction, a lot of energy is converted into thermal energy, this is а cause of spring wear on the contact points of the coils and of overheating of the machines and mechanisms. The known methods of increasing spring resourcefulness do not consider the issue of friction and wear of springs surfaces contact. Тhe new technologies for increasing the wear resistance of compression springs using contact predeformation are presented in the article. In this case, an additional axial load exceeding the load on the spring in the product by more than 5% and determined theoretically at the stage of development of the technological process is applied to the compressed spring coils into contact. The exposure time under axial load is 1–1.5 s. Serial springs were manufactured and two batches of experimental springs were produced using new technologies. The dispersion of the force parameters of the springs of experimental batch No. 1 as compared with serial springs was reduced by 14.3%, and as compared with experimental batch No. 2 by 42.9%. After cyclic tests the decrease of workload for serial springs averaged 1.17%; for springs of experimental batch No. 1, 0.23%; for springs of experimental batch No. 2, 0.45%. Contact clamping not only promotes the formation of useful residual stresses, but also increases the bearing capacity of the springs. The strip of hardened material is formed, which increases the wear resistance of the contacting surfaces of the coils and reduces friction due to parallel layering. On the contact places of the spring coils, the specific pressure decreases and the deformation wear resistance of the springs increases. Therefore, contact clamping should also be considered as a finishing operation to reduce friction on the places of contact of the spring’s coils and increasing their wear resistance.