What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The conventional auger bit structure 1 includes a rod body 11, a screw head 12 provided on one end of the rod body 11, a drill tail 13 provided on the other end of the rod body 11, and a plurality of threads 14 arranged around the rod body 11; Wherein, the periphery of the drill tail 13 defines a parting line 15, and the parting line 15 makes the drill tail 13 symmetrically divided into a side 131 and a side 132, and a cutting end 133 is formed at the junction of the end of the side 131 and the end of the side 132, respectively. The cutting end 133 is concavely provided with a quarter-turn chip flute 134 in the same direction of the helix, and the edge 132 continues the chip flute 134 and has a quarter-turn chip flute 135 with different helical curvatures. , by connecting the chip groove 134 and the chip groove 135 through different helical curvatures, the drill tail 13 can form a symmetrical and complete chip groove of 186 degrees.
flat washer is also called a flat washer. It is mainly stamped out of an iron plate. The shape is generally a flat washer with a hole in the middle. The size of this hole is generally determined according to customer requirements. There are 9 standards for flat washers in my country. From 2000 to 2002, GB/T97.3-2000, GB/T5286-2001, GB/T95-2002, GB/T96.1-2002, GB/T96.2 were approved and released respectively. -2002, GB/T97.1-2002, GB/T97.2-2002, GB/T97.4-2002 and GB/T5287-2002 Standard for flat washers. According to the performance grade of the flat washer, the author recommends the use of materials: ST12, ST13, Q235, Q215, Q195, etc. can be selected for the 100HV grade, and the surface hardness can reach about 110HV; 08F, 08Al, 10, 10F, etc. can be selected for the 140HV grade etc., the surface hardness can reach about 140HV; for 200HV and 300HV grades, 45, 50, 60, 70 or 65Mn steel should be selected, which can be quenched and tempered by heat treatment to meet the technical requirements of 200~300HV and 300~400HV. Because according to the standard, flat washers of 100HV and 140HV grades can be manufactured from mild steel. Most enterprises use Baosteel materials when selecting materials, which is convenient for cold stamping. The following is a brief description of Baosteel's standards. Compared with the BZJ407-1999 standard, there are major changes in Continuous Cold Rolled Low-Carbon Steel Plates and Strips and the enterprise standard: (1) The grades have been revised and integrated, and the grades have been changed from 8 commonly used to 5. St12 is changed to DC01; ST13 is changed to DC03; St14, St15 is changed to DC04; BSC2 is changed to DC05; St16, St14-T, BSC3 is changed to DC06. (2) The surface quality level is changed from two to three: the higher-level finishing surface (FB), the surface is allowed to have a small amount of defects that do not affect the formability and coating and plating adhesion, such as slight scratches, indentations, Pock, roll printing and oxidation color, etc. Premium Finished Surface (FC) products have no visible defects on the better of the two sides and must meet at least FB requirements on the other side. The super-advanced finishing (FD) product must not have any defects on the better side of the two sides, that is, it cannot affect the appearance quality after painting or the appearance quality after electroplating, and the other side must at least meet the requirements of FB. (3) The surface structure is modified from four to two, and the control value of surface roughness is increased. The average roughness Ra when the surface structure is pitted (D) is 0.6 μm. (4) The provisions on Si and residual elements in the chemical composition of the five grades have been cancelled, and the contents of elements such as C, S, and Alt have been revised.
The opening circlip is widely used in many industrial fields and plays a role in limiting the position of the parts. When in use, as long as the circlip is installed in the circlip groove of the part, the position of other matching parts can be effectively limited, so as to avoid the axial displacement of the matching parts. Since some opening circlips do not have circlip pliers installation holes, circlip pliers cannot be used and can only be installed by hand, which not only cannot effectively ensure the installation quality of the circlip, but also limits the efficiency of installation work.
As the most common hardware, screws and nuts are widely used in construction and machinery fields. However, existing screws and nuts are easily corroded to varying degrees in the natural environment, especially the threads on screws and nuts are corroded After that, the whole screw and nut are useless, and people have to discard them, which will inevitably lead to a lot of waste of resources.
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