What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
A screw is a tool that uses the physical and mathematical principles of the circular rotation and friction of an object to fasten the mechanism of the object step by step. A drill-tail screw is a screw with a self-tapping drill head on the front end of the screw. The screw is a common invention in people's production and life for thousands of years. According to the application field, it is the first invention of mankind. Drilling screw is a new invention in recent years, also called self-drilling screw. A screw is a common term for fasteners, an everyday colloquial language.
The tail of the drill tail screw is in the shape of a drill tail or a pointed tail, and no auxiliary processing is required. Drilling, tapping and locking can be directly carried out on the setting material and basic material, which greatly saves construction time. Compared with ordinary screws, its toughness and pull-out force and maintenance force are high, and it will not loosen for a long time after combination, so it is safe to use. Especially in the combination of construction, construction, residential and other places, self-tapping and self-drilling screws are the best economical fasteners in terms of workability, cost and reliability. Now the construction of high-rise buildings and high-speed traffic in mainland China requires more high-quality drill screws;
The maximum unscrewing torque of the lock nut is affected by many factors. For the research on the low-cycle fatigue performance of the lock nut, the pitch diameter of the thread, the helix angle and the bevel angle of the thread remain unchanged. Only the maximum elastic restoring force FNmax and the equivalent friction angle ρe of the thread piece will appear to a certain extent after repeated use. Change. Therefore, it is only necessary to analyze the variation law of the maximum unscrewing moment when the lock nut is subjected to cyclic load from these two aspects.
Self-locking nuts generally rely on friction. The principle is to press the embossed teeth into the preset holes of the sheet metal. Generally, the diameter of the square preset holes is slightly smaller than that of the rivet nut. The nut is connected with the locking mechanism. When the nut is tightened, the locking mechanism locks the ruler body, and the ruler frame cannot move freely to achieve the purpose of locking; when the nut is loosened, the locking mechanism disengages the ruler body, and the ruler frame edge body movement
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