What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The application range of the oil pump is very wide. When it is used, the oil pump needs to be assembled. During the assembly process, when the pin is driven into the pin hole, it is generally held by the operator with a hammer, and then aiming at the top of the pin to press. Into the hole, due to the relatively high tolerance requirements for the depth of the pin pressing and the side clearance (the gap between the pin and the groove wall), the traditional operation method not only causes a high rejection rate and a long training time for personnel, but also The slow processing speed affects the production efficiency.
Specification label broadcast representation format: Thread specification d=M12, nominal length L=80mm, and performance level 4.8 equal-length stud bolts are completely marked as: GB 901 M12×80 [1] Product example: Stud studs are generally required After surface treatment, there are many types of bolt surface treatment, commonly used are electroplating, blackening, oxidation, phosphating, electroless zinc flake coating treatment, etc. However, electroplated fasteners account for a large proportion of the actual use of fasteners. Especially in automobiles, tractors, home appliances, instrumentation, aerospace, communications and other industries and fields are more widely used. However, for threaded fasteners, not only a certain anti-corrosion capability is required in use, but also the interchangeability of threads must be ensured, which can also be called screwability here. In order to meet the dual-use performance of anti-corrosion and interchangeability required by threaded fasteners in use, it is very necessary to formulate special plating standards.
The existing method of tightening large screws is generally 1. After the nut is screwed to the connected piece by hammering + nut angle method, use a casing to connect the lever arm of the wrench, or use a free hammer to hammer the plate handle, Rotate the nut an additional angle to obtain the required preload. This is not only a primitive and labor-intensive fastening method, but also has great limitations, such as limited space, or the screw itself is a rotating shaft and so on, it is difficult to use this method.
Thread Code Broadcast Coarse Thread Series UNC Fine Thread Series UNF Extra Fine Thread Series UNEF Fixed Pitch Series UN Marking Method Broadcast Marking Method: Thread Diameter - Number of Threads per Inch Serial Code - Accuracy Grade Example: Coarse Thread Series 3/8—16 UNC— 2A Fine pitch series 3/8—24 UNF—2A Extra fine pitch series 3/8—32 UNEF—2A Fixed pitch series 3/8—20 UN—2A The first digit 3/8 indicates the outer diameter of the thread, in inches , to convert to metric unit mm, multiply by 25.4, that is, 3/8×25.4=9.525mm; the second and third digits 16, 24, 32, 20 are the number of teeth per inch (the number of teeth on the 25.4mm length); The text code UNC, UNF, UNEF, UN after the third digit is the series code, and the last two digits 2A are the precision grade. UNC: Unified Coarse Thread.
The above content is uploaded by Yueluo or the Internet. If there is any copyright issue, please contact [email protected].
