Iron two combination screws can be sucked up with magnets, but stainless steel two combination screws are difficult to be sucked up. Environmentally friendly three-combination screws and non-environmentally friendly ones are invisible to the naked eye and require mechanical testing. It cannot be judged with the naked eye and out of thin air. The specifications of the two combination screws need to be determined by the national standard. The salt spray of the two combination screws needs to be measured with a salt spray machine for how many hours.
Washers (spring) washers, circlips are elastic pads or card lock washers a washer that prevents bolts from loosening. The working principle of lock washers is very simple. It consists of two washers. The outside is a radial relief surface, and the inside is a helical tooth surface. When assembling, the inner helical tooth surfaces are opposite each other, and the outer radial raised surface is engaged with the contact surfaces at both ends. When the connecting piece is vibrated and the bolt tends to loosen, only the inner helical tooth surfaces of the two washers are allowed to face each other. Staggered movement, resulting in lifting tension, so as to achieve 100% locking.
The assembly of hollow rivets and flat head screws riveted on the cover plate is assembled in the product. Compared with the method of connecting with bolts, the loading and unloading speed can improve the efficiency by about 80% to 90%, and is widely used. The assembly needs to riveted hollow rivets and flat head screws on the cover plate, and ensure that the riveted flat head screws can rotate flexibly. When riveting, it is necessary to use special tools to riveted the hollow rivets, flat head screws and cover plates together for riveting. In the existing riveting process, the oval head screw is often damaged due to the action of external force. The positioning process is cumbersome and the work efficiency is low.
Plastic tree rivets are also called inverted tooth plastic rivets, also known as Christmas tree plastic rivets. The toothed flakes have good elasticity and can be directly manually pressed and installed in the round holes of the interference assembly. The toothed flakes can be installed according to the actual thickness and size. It can be fixed by self-adjustment. The design of the inverted tooth type is that the rivet is firmly fixed to the installation surface after installation, and it is not easy to be pulled out. It is suitable for fixing between soft materials such as foam, wood, rubber, and automobile interiors. Plastic tree rivets have excellent insulation, fire resistance, non-magnetic, heat insulation, light weight, high temperature resistance, high strength, corrosion resistance, and are widely used in various industrial fields.
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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