What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
High-strength hexagon head bolt combination screws for steel structures, mainly used in railway and highway bridges, boiler steel structures, industrial plants, high-rise civil buildings, tower and mast structures, hoisting machinery and their steel structures need to use friction-type high-strength bolt combinations for screws. It is characterized by an extra dodecagon at the end of the bolt, also known as the bolt. When installing, a special electric wrench must be used, which has two socket heads up and down, one is set on the hexagonal body of the nut, and the other is set on the decagon body of the outer hexagon screw. When tightening, apply a clockwise force to the nut, and apply an equal counterclockwise force to the dodecagon body of the bolt, so that the connecting neck between the end of the outer hexagon screw and the dodecagon body is subjected to torsion shearing until the neck is sheared. So far, the installation has come to an end. This torsion shear type high-strength outer hexagon screw is a one-time-use screw and generally cannot be removed after installation.
A rivet is a nail-shaped object with a cap on one end: in riveting, the parts being riveted are joined by their own deformation or by interference. There are many types of rivets, and they are informal. However, the two ends of conventional rivets are concentric, which is not suitable for special occasions.
Among the mold parts used in the can manufacturing industry, some product inner holes need to be processed with stop slots after heat treatment. The inner hole diameter of the product is φ28mm, the width of the slot is about 1.3mm, and the size and shape of the outer end face of the slot adjacent to the orifice The tolerance requirements are very strict, generally within the range of 0.02mm. If the CNC machine tool is used for cutting, the blade loss is very serious because the groove width is too narrow; if the inner hole grinding is used, there is no ready-made grinder and grinding wheel.
1. Correctly select the product a. Before use, confirm whether the mechanical properties of the product can meet the needs of use, such as the tensile strength of the screw and the guaranteed load of the nut. The length of the screw should be selected appropriately, and the 1-2 pitch of the nut will be exposed after tightening. b. Before use, check whether the threads are rough, and whether there is iron filings or dirt between the threads, which often lead to locking. c. The fasteners can be lubricated before use. It is recommended to use butter, molybdenum disulfide, mica, graphite or talc for lubrication. Generally, dipping wax is used for lubrication and anti-locking. [1] 2. Pay attention to the use method when using it. a. The speed and force of screwing in should be appropriate, not too fast or too large. Use a torque wrench or socket wrench as much as possible, and avoid using an adjustable wrench or an electric wrench. Excessive speed will cause the temperature to rise rapidly and cause lock-up. b. In the direction of force, the nut must be screwed in perpendicular to the axis of the screw. c. The use of washers can effectively prevent the problem of over-tightening.
The above content is uploaded by Yueluo or the Internet. If there is any copyright issue, please contact [email protected].
