Service HotlineThe drawing process has two purposes, one is to modify the size of the raw materials; the other is to obtain basic mechanical properties of the fasteners through deformation and strengthening. For medium carbon steel, medium carbon alloy steel also has another purpose, that is, to make the wire rod. The flaky cementite obtained after controlled cooling is cracked as much as possible during the drawing process to prepare for the subsequent spheroidization (softening) annealing to obtain granular cementite. However, some manufacturers arbitrarily reduce the drawing in order to reduce costs. The excessive reduction rate increases the work hardening tendency of the wire rod, which directly affects the cold heading performance of the wire rod. If the distribution of the reduction ratio of each pass is not appropriate, it will also cause torsional cracks in the wire rod during the drawing process. In addition, if the lubrication is not good during the drawing process, it can also cause regular transverse cracks in the cold drawn wire rod. The tangential direction of the wire rod and the wire drawing die is not concentric at the same time when the wire rod is rolled out of the die, which will cause the wear of the unilateral hole pattern of the wire drawing die to aggravate, make the inner hole out of round, and cause uneven drawing deformation in the circumferential direction of the wire. The roundness of the steel wire is out of tolerance, and the cross-sectional stress of the steel wire is not uniform during the cold heading process, which affects the cold heading pass rate. During the drawing process of the wire rod, the excessive surface reduction ratio will deteriorate the surface quality of the steel wire, while the too low surface reduction ratio is not conducive to the crushing of the flaky cementite, and it is difficult to obtain as much granular cementite as possible. , that is, the spheroidization rate of cementite is low, which is extremely unfavorable to the cold heading performance of the steel wire. For the bar and wire rod produced by the drawing method, the partial surface reduction rate is directly controlled within the range of 10%-15%.
The lifting ring screw should be made of 20 or 25 steel (GB699). The lifting ring screw must be forged as a whole. The forgings should be normalized and the oxide scale should be removed. The grain size of the finished product should not be lower than grade 5 (YB27-77). There must be over-burning, crack defects.
4. Manufacturing and assembly Due to the limitations of manufacturing technology and accuracy, there are sharp corners on the edge of the thread or the dimensional coordination between parts is not coordinated. During the initial assembly, the screw-in and screw-out torque may fluctuate or fluctuate to a certain extent. After a certain number of running-in, more accurate reusability characteristics of the lock nut can be obtained.
Existing bolt pairs usually include bolts, nuts and washers, and their specific structures and usage methods are traditionally known and common in life. They will not be described in detail here. You can find relevant bolt pairs by searching for bolt pairs on the Internet. Information picture, the structure of the ordinary bolt pair has basically no structural improvement since it was used as a fastener. The production requirements of ordinary bolt pairs are the basic material, structural strength, and accuracy requirements, while the tightening and anti-loosening requirements The requirements of the effect are basically to achieve the problem of tightening and anti-loosening by using elastic washers, anti-loosening washers or using double nuts.
Cylindrical pins are widely used for positioning or connecting components on mechanical equipment, and the cylindrical pins are fixed in the pin holes by means of interference fit. Cylindrical pins are generally processed by a grinding machine and a punch former, but the above processing methods have complex operation procedures, high processing equipment and high processing costs.
We have many years of experience in the production and sales of screws, nuts, flat washers, etc. The main products are: PP polypropylene DIN933 screws, DIN1481 pins, nut set screws, DIN6796 gaskets and other products, we can provide you with suitable fastener solutions for you Program.
