Service HotlineThread 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 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.
The blind rivet is realized by pulling the core head. With the help of a force from the inside to the outside, under the action of the unidirectional pulling force, the pulling screw is pulled upwards, which causes the outer collar material to expand and deform, resulting in a sexual tightening force. , After the riveting is completed, the tension screw in the middle part breaks and falls out. Since a large pulling force is required to cause the rivet to expand and deform, the tensile screw is longer and accounts for about 60-80% of the total length of the rivet. At the same time, due to the limitation of the deformation mode, it is difficult for the blind rivet to be made into a hexagonal structure like a rivet nut, so the torsion resistance of its connection is low.
In the switchgear of high and low voltage power equipment, the surface of many switchgear shells is painted or sprayed with plastic, and the installation beams and other parts of the switchgear and the entire cabinet must be continuously grounded according to the requirements of switchgear standards to improve the safe use of equipment. Because the common screw, spring washer, flat washer and nut type structural connection between the surface of the shell and the metal mounting beam cannot meet the requirements of grounding continuity, in order to meet the requirements, the surface of the shell is painted or Before spraying, special grounding studs must be welded. With the increase of installation beams, the number of welded studs must also increase, which increases the complexity of the product processing technology, wastes man-hours and increases costs.
hand screw is a screw with a plastic head, and the user fixes the hand screw by turning the plastic head by hand. At present, a hand screw is disclosed in the market publication number CN202203253U, which includes a plastic head and a screw rod, the plastic head and the screw rod are connected together, and the height of the plastic head is higher than that of an ordinary screw, and the height is 12 cm. The screw of the hand screw is fixed in the plastic head by glue. After a period of use, the aging of the glue leads to the loosening of the screw and the plastic head. When the plastic head is stressed, the screw rod comes out of the plastic head, which affects the normal use of the hand screw.
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