What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
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.
In the design of modern aviation and aerospace vehicles, in order to reduce weight and save space, the space of the fastening installation system is getting narrower and narrower, and blind hole installation is often required. In this case, single-sided riveting installation is usually used for fastening connection. At present, this kind of fastening connection products are mainly blind rivets. The riveting installation principle of blind rivets is to use the method of pulling, pulling the mandrel, and extruding the nail sleeve to deform it at the blind end to achieve the function of fastened connection. This kind of fastening connection method requires special riveting, generally imported riveting, the replacement of internal parts is expensive, the installation process is complicated, and the installation cost is high.
Generally, the T-bolt structure is common, and its blank shape can be completed at one time on a multi-station cold heading machine. But for T-bolts with relatively rare structures, (for example: the intersection of ¢14x42 cylinder (head) + ¢12 cylinder, the two cylinders form a 90° intersection) due to the special structure, the head Cold forming is difficult, and the traditional processing route is: die casting blank → deburring → turning processing → grinding blank diameter → wire rolling → heat treatment → surface treatment → finished product packaging.
As we all know, bolt and nut kits are commonly used fastening parts, but when ordinary bolt fasteners are used in a large number of parts, because the nuts and bolts are engaged by threads, manual or machine tightening is required, and during installation, It is easy to slip, and the bolts need to be operated in both directions, and a pair of bolts and nuts cannot be installed quickly, which reduces the installation efficiency.
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