What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Traditional rivet nuts are usually cylindrical, and special tools are required to complete the riveting operation between the workpiece and the sheet, and tools are completely required for locking. And in the actual production process, it is often encountered that there are square holes on the workpiece, and bolts need to be installed in the square holes, especially in the power cabinet and the control cabinet when the workpiece with prefabricated square holes is used as the main frame, due to Due to the special structure of the workpiece, the installation nut can only be inserted from the side, and the installation cannot be completed when the side installation space is limited, which brings inconvenience to the installation.
The semicircular key is a kind of key, the upper surface is a plane, the lower surface is a semicircular arc surface, the two sides are parallel, commonly known as the crescent key. It is basically the same as the flat key connection method, but it is more convenient to manufacture and disassemble than the flat key, and is especially suitable for the connection between the tapered shaft and the hub. The half-round key transmits torque on the side, but the keyway is deep, which weakens the shaft greatly. Due to the deep keyway, the bottom of the keyway is easily deformed after the shaft is heat treated. Therefore, when the semicircular key and the keyway are assembled in a transitional fit relationship, the interference between the lower part of the semicircular key and the bottom of the keyway often occurs, resulting in difficult or impossible assembly. Assembly situation. In order to solve the above technical problems, the current method is to make the thickness of the semicircular key appropriately thin, so that the semicircular key and the keyway are clearance fit, which brings about a large gap between the upper part of the semicircular key and the keyway, and the semicircular key is in operation. Difficult to locate in the keyway, affecting smooth transmission.
Materials and main equipment: 1.1 Bolts, nuts and washers shall be accompanied by quality certificates and shall comply with design requirements and national standards. 1.2 The high-strength bolts should be stored in categories according to their specifications, and should be protected from rain and moisture. Do not use if the bolts and nuts are not matched and the threads are damaged. If the bolts, nuts and washers are corroded, the tightening axial force should be sampled and used only after meeting the requirements. Bolts, etc. shall not be contaminated by soil or oil, and shall be kept clean and dry. It must be used in the same batch according to the batch number, and must not be mixed or mixed. 1.3 Main tools: electric torque wrench and controller, manual torque wrench, manual wrench, wire brush, tool bag, etc. 2 Operating conditions: 2.1 Friction surface treatment: The friction surface is treated by sandblasting, grinding wheel grinding and other methods, and the friction coefficient should meet the design requirements (a requirement is that the Q235 steel is above 0.45, and the 16 manganese steel is above 0.55). The friction surface wood is allowed to have residual iron oxide scale. The treated friction surface can generate red rust surface and then install the bolts (generally stored in the open air for about 10d). The sandblasted friction surface can be installed without rusting. When grinding with a grinding wheel, the grinding range is not less than 4 times the diameter of the bolt, the grinding direction is perpendicular to the direction of force, and the friction surface after grinding should be free of obvious unevenness. The friction surface should be prevented from being polluted by oil or paint. If polluted, it should be cleaned thoroughly. 2.2 Check the hole size of the bolt hole, the burrs on the edge of the hole must be removed. 2.3 The bolts, nuts and washers of the same batch number and specification should be packaged for use. 2.4 Electric wrenches and manual wrenches should be calibrated.
Fasteners are a type of mechanical parts that are used for fastening connections and are widely used. They are used in a wide range of industries, including energy, electronics, electrical appliances, machinery, chemicals, metallurgy, molds, hydraulics and other industries. This kind of fastener is a widely used mechanical basic part. It is characterized by a wide variety of specifications, different performance and uses, and a very high degree of standardization, serialization and generalization. Therefore, some people also refer to a type of fasteners with existing standards as standard fasteners, or simply as standard parts.
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