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 blind rivet is realized by pulling the core head. With the help of a force from the inside to the outside, under the action of the unidirectional pulling force, the pulling screw is pulled upwards, which causes the outer collar material to expand and deform, resulting in a sexual tightening force. , After the riveting is completed, the tension screw in the middle part breaks and falls out. Since a large pulling force is required to cause the rivet to expand and deform, the tensile screw is longer and accounts for about 60-80% of the total length of the rivet. At the same time, due to the limitation of the deformation mode, it is difficult for the blind rivet to be made into a hexagonal structure like a rivet nut, so the torsion resistance of its connection is low.
1. The expansion phenomenon of the spring washer is generally not the problem of the spring washer itself. 2. The spring washer with the expansion ring must be subjected to a radial external tension. The external tension is derived from the tightening axial force generated by the tightening torque. The chamfer creates a radial component of the axial clamping force, which expands the opening of the spring washer. The smaller the chamfer diameter, the greater the possibility of ring expansion. 4. Adding a flat washer between the nut and the spring washer helps to slow down or prevent the expansion of the ring, but the flat washer is too thin or too soft. Prevent ring expansion 5. The reason for the hydrogen embrittlement fracture of spring washers is generally due to unreasonable heat treatment process and the failure of hydrogen removal treatment after electro-galvanizing. A large number of tests and long-term practical experience have confirmed the above analysis.
The commonly used tools for fixing screws on the surface of the workpiece are electric screwdrivers and manual screwdrivers. Both of these screwdrivers manually attach the screws to the bits of the electric screwdriver or manual screwdriver, and then fix the screws on the surface of the workpiece. The screwdriver is inefficient in fixing the screw, and cannot accurately locate the screw fixing point.
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