What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
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 force condition of the screw is broadcasted: 1) Self-weight G; 2) Torque M required to overcome material resistance; 3) Axial force P generated by material pressure. Screw screw screw is generally scrapped due to long-term wear, the gap between the screw and the barrel is too large and cannot be extruded normally, but there are also examples of damage due to improper design or improper operation. Therefore, the screw should also meet certain strength requirements. 4) The dangerous section of the screw is generally at the smallest thread root diameter in the feeding section. According to material mechanics, for plastic materials, the composite stress is calculated by the third strength theory, and its strength conditions are:
Nuts and bolts are one of the most widely used fasteners in modern mechanical structures. At present, the common metric bolts and nuts are generally trapezoidal in cross-section. The connection between the bolt and the nut is prone to loosening under severe vibration, or even falls off by itself, and the tightening force of the bolt and nut thread is mainly concentrated in the bolt thread and Between the teeth of the first few threads where the threads of the nut are in contact, resulting in loosening of the fastener and sliding pressure of the threads
Fan rivets are specially designed for manual installation. They can be pulled in through the holes of the panel or the bottom frame. They are made of elastomer material with good toughness and can be installed quickly even in interference assembly. The design is clever and has elastic function. It is not easy to slide out after being pulled in with the corresponding aperture. The fan rivets are mainly used in the fixing of electronic computer case fans, heat sinks and chips, with anti-vibration and noise reduction.
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