What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Please refer to FIG. 1 , which is a cross-sectional view of a conventional screw and screw washer for locking two metal parts. The screw 100 is combined with the screw washer 110 to lock the metal parts 120 and 130 . The screw washer 110 includes a washer portion 112 and a body washer portion 114 . The washer portion 112 is used for electrically isolating the screw head 102 from the metal piece 120 , and the screw body washer portion 114 is used for electrically isolating the screw body 104 and the metal piece 120 . Therefore, through the design of the screw washer 110 , the screw 100 can be isolated from conducting the metal parts 120 and 130 .
Bearings are an important component in contemporary machinery and equipment. Its main function is to support the mechanical rotating body, reduce the friction coefficient during its movement, and ensure its rotation accuracy. Every time the locomotive is repaired, the end cover of the axle box needs to be disassembled, the axle head is tested for flaws and the bearing is supplemented with grease, which involves the disassembly and assembly of the axle box bearing retaining ring. The existing disassembly method is to use the traditional method of inserting two tongue pins into the gap between the bearing retaining ring and the axle box to pry left and right, and slowly separate it from the axle head. Because the clearance between the bearing retaining ring and the shaft head is small, and the adhesive force generated by the grease in the axle box is large, if the disassembly method is not appropriate or the force is not uniform, it will cause certain damage to the axle box body and the bearing retaining ring or jam. It is easy to cause damage to the bearing, and there is also the possibility of damage to the disassembly and assembly tools, so the safety risk is high, and each disassembly and assembly of the bearing retaining ring is time-consuming and laborious, labor-intensive, low-efficiency, and increased maintenance costs.
Process equipment for aircraft production (hereinafter referred to as tooling) is directly used for part forming and component assembly. In order to satisfy the loading and unloading of aircraft parts and components during the use of the tooling, the tooling generally adopts a structural form that is easy to disassemble as a whole. In the field of aircraft process equipment manufacturing, positioning pins are usually used to connect and position the detachable parts of the tooling. At present, this kind of locating pin is divided into two types: direct pull-out locating pin and tie-suspended locating pin.
Large, countersunk, and thin rivet nuts can be produced according to different die angles. Then the cold forged rivet nut is degreasing, cleaned and annealed, and then extruded and tapped and surface electroplated. Since the rivet nut is formed by cold extrusion of low carbon steel, it has high mechanical properties. Specifically, the tensile strength of M3 is 250Kg, the shear strength is 140Kg; the tensile strength of M4 is 700Kg, the shear strength is 220Kg; the tensile strength of M5 1100Kg, shear force 380Kg; M6 tensile force 1750Kg, shear force 450Kg; M8 tensile force 2650Kg, shear force 660Kg.
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