What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
At present, injection molding screws are widely used in various electronic and automotive components, including a body, the middle of which is provided with a through hole 3, the body head 1 has a hexagonal cross-section, and the tail 2 is provided with screw teeth. When in use, the middle through hole 3 of the body will first put the wire harness, and then fix it by injection molding from the head I, and the threads of the tail 7 should be connected and installed with other components. Because the head I of the main body is hexagonal, the torque provided after injection molding is insufficient. Therefore, after the external thread is installed and connected with other components, the head is prone to slip, the installation is not reliable, and there is no push-pull force, resulting in product failure and increased safety hazards.
In addition, in the prior art, rivets are also used to riveted screws on metal plates. The rivets are nail-shaped objects with a cap at one end. In riveting, the riveted parts are connected by their own deformation or interference. When using rivets, it is necessary to set moderately sized positioning holes in the corresponding positions of the two metal plates, and the rivets directly penetrate into the positioning holes and then riveted. Because this riveting method does not require welding, it will leave a hole on the back of the metal plate. Therefore, in the prior art, the surfaces of the two metal plates after riveting are covered with a layer of smooth metal skin to cover the riveting marks, which will also increase the overall cost, including metal The cost of the skin and the increase in the manufacturing process, while the riveting process is limited, the connection between all metal plates cannot be universal.
At present, injection molding screws are widely used in various electronic and automotive components, including a body, the middle of which is provided with a through hole 3, the body head 1 has a hexagonal cross-section, and the tail 2 is provided with screw teeth. When in use, the middle through hole 3 of the body will first put the wire harness, and then fix it by injection molding from the head I, and the threads of the tail 7 should be connected and installed with other components. Because the head I of the main body is hexagonal, the torque provided after injection molding is insufficient. Therefore, after the external thread is installed and connected with other components, the head is prone to slip, the installation is not reliable, and there is no push-pull force, resulting in product failure and increased safety hazards.
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.
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