Thread selection of non-standard nuts

Today, the editor will tell you some little knowledge about Qingdao non-standard nuts.

First of all, in all walks of life in modern society, especially in machinery, construction and other industries, few products can avoid fasteners such as bolts and nuts. With the rapid development of modern industry, people continue to summarize design and production experience, and gradually develop a series of bolts and nuts related to the standard system, including commonly used mechanical properties, size bolts and nuts, bolt hole sizes and tightening standards, etc. The design, processing and installation work has brought great convenience. However, due to the complexity of these standard systems and the relative dispersion of standards, it brings relative inconvenience to the design and installation. This article mainly summarizes the design and installation of bolts and nuts to make the design and installation of bolts and nuts more standardized, so as to ensure the quality of crystal production.

Selection of thread

The thread of bolts and nuts is generally selected with a tooth profile angle of 60°, which has high root strength and good self-locking performance. The thread conforms to the national standard of GB/T 192-2003 "Basic Tooth Profile of Ordinary Thread". According to different pitches, connecting threads are divided into coarse threads and fine threads. The thread diameter of fine thread is larger than that of coarse thread, so the use of fine thread bolts has high strength and good self-locking performance. However, the filament is not wear-resistant, has low shear strength, and is easy to slip. Coarse threads are often used in general design; for thin-walled parts that have to withstand vibration and impact and require large dynamic loads and high precision requirements, the mechanism generally selects fine threads; in high temperature areas and the use of hydraulic tensioning device installation bolts, thread design, In order to disassemble, generally in large-diameter bolt thread, the diameter is slightly smaller than the corresponding specification and track design size 6g tolerance size, and the nut thread is still used 6h tolerance, suitable for this bolt and nut, the gap increases, so it will be easy to remove. This design is reflected in marine diesel engines, especially the bolts of the exhaust system and the main bolts pulled by the hydraulic tensioner.