What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
GB bolts are generally divided into two types: GB30 bolts and GB21 bolts. The difference is that the hexagonal head of GB30 is larger than that of GB21. The materials are all used: Q235. The grade is 4.8, the hardness is weak, and it is used for parts with low hardness requirements and infrequent activities, which are called ordinary bolts. The most typical use: machinery, construction, fixing, fastening.
The existing structure is found in the practical application experience that there are still the following problems and drawbacks: the screw structure and the screw space are combined with each other in a complementary manner, so they can provide a higher torque value, however, not every workpiece. The combination requires a high torque value, so it often results in excess quality. Although the price of the screw is low, if it can change the unchanging structure of the traditional screw, it can provide a technical means to simplify (change) the process. The effect of improving production capacity and convenience of use is indeed a technical bottleneck that the relevant industry should break through.
The main function of the spring washer is to prevent the nut from loosening. It is also known that: the existing spring washer is a ring made of spring steel, and then a gap is cut in the diameter direction on the ring, and the heads on both sides of the gap are cut. The material of the part is turned to two different sides of the ring to form a pawl, and the purpose of preventing loosening is achieved by the fit between the pawl and the nut on the surface and the workpiece. Obviously, only one pawl is used to achieve the purpose of preventing loosening. Since the braking force generated by one pawl is limited, there are defects of poor braking effect and poor anti-loosening effect.
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. , using the chip groove 134 and the chip groove 135 to be connected by different helical curvatures, so that the drill tail 13 can form a symmetrical and complete chip groove of 190 degrees.
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