What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
In the non-standard mechanical design, when the middle part of the long shaft or rod-shaped structure needs to be threaded, the end is limited and the nut cannot be penetrated, which will cause the problem that the installation cannot be realized. In order to solve this problem, it often has to be cancelled. It is not conducive to the realization of equipment cost reduction and optimal function, and even the problem cannot be solved, and another way out is needed.
According to relevant standards, the performance grades of carbon steel and alloy steel bolts are divided into more than 10 grades such as 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, etc. Among them, the bolts of grade 8.8 and above are made of low-carbon alloy steel or medium Carbon steel and heat treatment (quenching, tempering) are generally called high-strength bolts, and the rest are generally called ordinary bolts. The bolt performance grade label consists of two parts of numbers, which represent the nominal tensile strength value and yield ratio of the bolt material respectively. Stainless steel bolts are divided into A1-50, A1-70, A1-80, A2-50, A2-70, A2-80, A3-50, A3-70, A3-80, A4-50, A4-70, A4-80, A5-50, A5-70, A5-80, C1-50, C1-70, C1-110, C4-50, C4-70, C3-80, F1-45, F1- 60. The first letter and number represent the stainless steel group, and the second and third numbers represent 1/10 of the tensile strength. [2]
Specification Model Screw Specification Model Example: 4 X 10 PW AHC (+) ① ② ③ ④ ⑤ ⑥ ⑦ ① Screw Diameter ② Screw Length ③ Screw Head Type B: Spherical Cylindrical; C: Cylindrical; F (K): Countersunk ; H: Hexagon head; HW: Hexagon head with washer; O: Half countersunk head; P: Plain head; R: Half head; PW: Plain head with washer; T: Large flat head; V: Mushroom head;
In actual use, the rivet rod body 3-2 is passed through the riveting plate 6 and the riveting plate 7, and the rivet dome head 3-1 is placed in the mold cavity 1-1, and the cover mold 2 is driven by the riveting machine to impact the rivet rod body 3-2. Because the center of the cover mold 2 is provided with a cavity 2-1 that matches the shape of the rivet dome 3-3, the end of the rivet rod 3-2 will form the rivet dome 3-3. However, due to the rivet When the riveting machine is impacted and vibrated, a large amount of oxide slag 4 will be generated, and the oxide slag 4 will slide down the surface of the cavity 1-1 to the bottom of the cavity 1-1 and accumulate. At this time, the temperature of the rivet is very high and the plasticity is very good. The hardness is extremely low and it is easy to form. Therefore, the accumulated oxide slag 4 squeezes the surface of the rivet dome 3-1 and the bottom surface of the cavity 1-1 to form pits, and causes wear on the bottom surface of the cavity, not only It affects the riveting quality, riveting strength and appearance quality of the rivet, and also affects the quality of the rivet die, resulting in economic losses.
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