The anti-theft screw of this structure has two disadvantages. One is that the polygonal block moves up and down in the polygonal hole, and the polygonal hole in the connecting piece and the polygonal hole on the threaded part have no limit structure. Because of the polygonal structure, the two If the polygonal holes of the parts cannot be aligned, dislocation occurs, and any edge may block the up and down movement of the polygonal block, which is very unsmooth during use. The second is that the shell of the lock cylinder and the hexagonal part are connected by pins, and the pins are exposed on the hexagonal parts, which are easily damaged and leave opportunities for theft; once the pin is pried off, the lock cylinder will be taken out, and the entire anti-theft screw will be lost. and the pin fixation is sometimes unstable, which is detrimental to theft.
The maximum unscrewing torque of the lock nut is affected by many factors. For the research on the low-cycle fatigue performance of the lock nut, the pitch diameter of the thread, the helix angle and the bevel angle of the thread remain unchanged. Only the maximum elastic restoring force FNmax and the equivalent friction angle ρe of the thread piece will appear to a certain extent after repeated use. Change. Therefore, it is only necessary to analyze the variation law of the maximum unscrewing moment when the lock nut is subjected to cyclic load from these two aspects.
Blind rivets (blind rivets) --------- rivet body (rivet body) mandrel (rivet stem or rivet mandrel). It is a type of rivet for single-sided riveting, but it must be riveted with a special tool - a rivet gun (manual, electric, pneumatic). When riveting, the rivet core is pulled by a special rivet gun to expand the rivet body and play a riveting role. This type of rivet is especially suitable for riveting occasions where it is inconvenient to use ordinary rivets (riveting from both sides), so it is widely used in construction, automobiles , ships, aircraft, machinery, electrical appliances, furniture and other products. Among them, the open-type oblate head blind rivets are the most widely used, the countersunk head blind rivets are suitable for riveting occasions where the surface needs to be smooth, and the closed blind rivets are suitable for riveting occasions that require high load and certain sealing performance.
The inner tooth elastic washer and the outer tooth elastic washer have many sharp elastic warping teeth on the circumference, which are pressed against the supporting surface and can prevent the loosening of the fastener. The inner tooth elastic washer is used under the screw head with smaller head size; the outer tooth elastic washer is mostly used under the bolt head and the nut. The elastic washer with teeth is smaller than the ordinary spring washer, and the fastener is evenly stressed and reliable to prevent loosening, but it is not suitable for frequent disassembly. Wave spring washer GB: GB/T 7246-1987 Wave washer is divided into WG type, WL type, WN type WG type wave washer WG type wave washer is an open elastic washer, which can usually be installed in a small space, such as giving The bearing is prestressed to reduce the noise of the bearing operation and improve the running accuracy and stability of the bearing. In addition, there are a large number of applied materials in electronic appliances, such as carbon steel, stainless steel, copper alloy and so on. WL-type wave washer WL-type wave washer is a lap-type elastic washer, which can usually be installed in a small space, such as prestressing the bearing, reducing the noise of the bearing operation, and improving the running accuracy and stability of the bearing. There are also a large number of applications in electronic appliances. Materials are carbon steel, stainless steel, copper alloy, etc. WN type wave washer WN type wave washer is a multi-layer wave crest overlapping elastic washer. Compared with the WL type, this series is composed of multi-layer materials, so the K value curve under the same compression stroke is flatter than that of the WL type, which is suitable for elastic force. Larger, and the elastic release of the entire working stroke is required to be more uniform. The materials used are carbon steel, stainless steel, copper alloy, etc. Disc spring washer Disc spring washer, also known as Belleville spring washer, was invented by the French Belleville. DIN6796 Disc Spring Washers (HDS Series) are lock washers designed for bolted and screwed connections. It is designed and manufactured according to DIN 6796 for the connection of medium or high strength bolts and screws. High bearing loads and elastic recovery make the HDS series very effective, and the bolt tension can withstand slack due to: wear of consumables, creep, relaxation, thermal expansion, contraction, or compression of seals. The HDS series increases the elasticity of the screw several times. It can effectively replace the ordinary spring washer, but it is not suitable for the combination of lock washer and flat washer. Since the HDS series is a disc spring that can be folded or overlapped. The combination of the butt joint can increase the deformation of the disc spring group, and the combination of the overlapping method can increase the spring force of the disc spring group. The ideal installation method is to flatten as much as possible. The closer it is to the flattened state, the faster the tension torque increases, and the proper bolt tension can be obtained without a torque wrench.
Countersunk rivet is a kind of part that uses its own deformation or interference connection to connect and position two objects in riveting. It is widely used in automobiles, vehicles, electromechanical products, aerospace products and other fields. When the countersunk head rivet is used, the head of the rivet sinks into the connected parts in whole or in part. This structure is mostly used for parts that require a smooth and smooth appearance. The standard structure of countersunk head rivets is specified in the national aviation standard, national standard and national standard, and the countersunk head rivets involved in these standards are all standard rotary structures.
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