What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Bolts or screws and flat washers assemblies GB/T 9074.1-2002 Cross recessed head screws and external serrated lock washers assemblies GB 9074.2-88 Cross recessed pan head screws and spring washers assemblies GB 9074.3-88 Cross recessed pan head screws, springs Washer and flat washer assembly GB 9074.4-88 Cross recessed small pan head screw and flat washer assembly GB 9074.5-88 Cross recessed small pan head screw and large washer assembly GB 9074.6-88 [1] Cross recessed small pan head screw and spring washer Assembly GB 9074.7-88 Cross recessed pan head screw, spring washer and flat washer assembly GB 9074.8-88 Cross recessed countersunk head screw and conical lock washer assembly GB 9074.9-88 Cross recessed countersunk head screw and conical lock Tight washer assembly GB 9074.10-88 Cross groove hexagon head bolt and flat washer assembly GB 9074.11-88 Cross groove hexagon head bolt and spring washer assembly GB 9074.12-88 Cross groove hexagon head bolt, spring washer and flat Washer assembly GB9074.13-88 Hexagon head bolt and spring washer assembly GB 9074.15-88 Hexagon head bolt and external serrated lock washer assembly GB 9074.16-88 Hexagon head bolt, spring washer and flat washer assembly GB 9074.17-88 From Tapping screw and flat washer assembly GB /T 9074.18-2002 Cross recessed hexagon head self-tapping screw and flat washer assembly GB 9074.20-88 Cross recessed hexagonal head self-tapping screw and large washer assembly GB 9074.21-88 For assembly Spring Washers GB 9074.26-88 External Serrated Lock Washers for Assemblies GB 9074.27-88 Conical Lock Washers for Assemblies GB 9074.28-88.
④ Screw tooth type A: Self-tapping sharp tail (Japanese standard type 1) sparse AB: Self-tapping sharp tail (Japanese standard type 4) dense; B: Self-tapping flat tail (Japanese standard type 2) sparse; C: Self-tapping Tapping flat tail (the third type of Japanese standard) dense; P: double wire teeth Type triangle teeth CCT: C type triangle teeth PTT: P type triangle teeth STT: S type triangle teeth
The technical process of nickel-phosphorus plating for high-strength bolts consists of three parts: The first part is the pre-treatment process, including the precision and appearance inspection of high-strength bolts before plating, manual degreasing, immersion degreasing, pickling, electro-activation and flash nickel plating and other processes; the second part is the electroless nickel plating treatment process; the third part is the post-treatment process, including the processes of hydrogen-displacing heat treatment, polishing and finished product inspection. As follows: Bolt chemical composition inspection → bolt pre-plating accuracy, visual inspection → manual degreasing → visual inspection → immersion degreasing → hot water washing → cold water washing → pickling → cold water washing → electric activation → cold water washing → flash nickel plating → cold water washing → Deionized water washing → Electroless nickel plating → Deionized water washing → Cold water washing → Hydrogen removal → Polishing → Finished product inspection.
The flat screw mainly includes a rotating part and a screw locking part, wherein the rotating part and the screw locking part are respectively flat-shaped structures; At least two sides of the screw lock portion are respectively provided with tooth rows, and the two tooth rows are mutually dislocated, so that the screw lock portion can be locked in a pre-formed screw hole in the workpiece.
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