Service HotlineThe capped nut can prevent the bolt connection from directly contacting with the outside world, which is corroded and makes it difficult to disassemble later. Nuts with caps in the prior art are mostly of one-piece structure, and the surface is not treated with anti-oxidation, which is easy to be corroded. In addition to the protective effect, the fastening method is the same as that of ordinary nuts, so it is easy to loosen when subjected to severe vibration. .
The front wall sound insulation pad is used to absorb the heat and noise transmitted by the firewall, and also plays the role of heat insulation and vibration isolation, ensuring a relatively quiet and comfortable environment in the car and improving ride comfort. As shown in FIGS. 1 and 2 , the front wall sound insulation and heat insulation pad 101 is generally fixed to the vehicle body by means of screw buckles 102 . The screws 100 are clamped by the clamping feet 103 in the screw The limiting rib 104 clamps the screw 100. After the screw 100 is clamped into the screw buckle 102, the tail end of the screw 100 is exposed, which is easy to scratch the operator when assembling other components, and the exposed screw 100 is easy to cause corrosion, thereby affecting the connection strength of the screw 100, and also The service life of the screw 107 is reduced.
Anchor bolts are also known as stiffened anchor plate anchor bolts, welded anchor bolts, anchor claw anchor bolts, rib plate anchor bolts, anchor bolts, anchor screws, anchor wires, etc. It is specially designed to be buried in the concrete foundation and used as the base for fixing various machines and equipment. Figure 7 anchor bolts are the most commonly used anchor bolts. It is generally made of Q235 steel, with high strength using Q345B or 16Mn material, and also using 40Cr material to process 8.8-strength products, and occasionally using secondary or tertiary rebar. Anchor bolts are divided into wool, thick rod and thin rod. The wool material is the raw material steel, which is directly processed from round steel or wire without modification; thick rods or called A-type, thin rods or B-type, are processed from steel modified into the corresponding required rod diameter. Welded anchor bolts are made of single-headed bolts welded with stiffened iron plates. Its anti-pulling ability is strong. According to the different conditions of use, it can reach 3.6, 4.8, 6.8, 8.8 and other grades respectively. The tensile capacity of 3.6 grade 7-shaped anchor bolts is the tensile capacity of the steel itself. The tensile strength of anchor bolts directly processed from Q345B or 16Mn raw materials can reach a tensile strength of 5.8. The tensile strength of grades 4.8, 5.8, 6.8 and 8.8 refer to the provisions on mechanical properties in GB/T3098.1.
Therefore, in order to obtain fasteners that meet the requirements, it is usually necessary to anneal the middle sections of bolts, rivets, etc. to reduce the hardness of the middle sections, while ensuring the hardness of the heads of bolts, rivets, etc. At present, the existing process adopts ultra-high frequency induction heating equipment to instantly heat the middle section and reduce the hardness. However, this process requires a lot of control, and the heating time is slightly longer, which affects the hardness of the head, and the mass production is very unstable, which is easy to cause the rivet to fail. At the same time, the cost of ultra-high frequency equipment is high and the power consumption is large, which is not conducive to mass production and energy saving. Environmental friendly.
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.
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