What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The anti-theft screw of this structure has two disadvantages. One is that the polygonal block moves up and down in the polygonal hole, and the polygonal hole in the connecting piece and the polygonal hole on the threaded part have no limit structure. Because of the polygonal structure, the two If the polygonal holes of the parts cannot be aligned, dislocation occurs, and any edge may block the up and down movement of the polygonal block, which is very unsmooth during use. The second is that the shell of the lock cylinder and the hexagonal part are connected by pins, and the pins are exposed on the hexagonal parts, which are easily damaged and leave opportunities for theft; once the pin is pried off, the lock cylinder will be taken out, and the entire anti-theft screw will be lost. and the pin fixation is sometimes unstable, which is detrimental to theft.
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-tight 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 6 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.
screw with a gasket includes a screw head and a screw connection part connected with the screw head, the screw connection part is provided with a thread, and a transition part is provided between the screw head and the thread provided on the screw connection part , the diameter of the transition part is smaller than the diameter of the thread, the transition part is sleeved with a plastic washer, the inner ring of the plastic washer is a polygon, and the diameter of the inscribed circle of the inner ring of the plastic washer is smaller than the diameter of the thread. The utility model replaces the traditional metal washer with a plastic washer, which avoids the phenomenon that the washer causes wear on the connection base. The inner hole of the plastic washer adopts a polygonal design, and the diameter of the inscribed circle of the inner ring of the plastic washer is smaller than the diameter of the thread, which is in the same shape as the thread. The multi-point contact solves the problem that the washer is easy to slip off due to the circular design of the inner hole of the traditional metal washer, and improves the assembly efficiency of the screw.
Yueluo relates to a self-tapping screw according to the preamble of claim 1. A self-tapping screw is known from EP0623759B1, the ratio of the outer diameter to the smaller diameter of the self-tapping screw is about 1.25-1.5, the ratio of the outer diameter to the pitch lead is about 1.5-1.6 and the thread The flank angles of , are < 50° and ≥ 35°. EP0433484B1 proposes a self-tapping screw whose thread is provided with cutting teeth of approximately arcuate design, and the cutting edge and the thread crest are at the same horizontal position and are set in opposite directions. One purpose of Yueluo is to realize a general type of self-tapping screw so that it can be screwed particularly easily into holes drilled in concrete or other materials such as bricks and the like. According to Yueluo, this object is achieved by the features in the characterizing part of claim 1, and surprisingly, it has been found that the parallel arrangement of the flanks, ie with a flank angle of about 0°, will make screwing particularly easy when screwing in , especially if the diameter of the hole varies within an allowable tolerance. One reason may be due to the fact that there is no lateral pressure on the material screwed into the thread, even if threads of different depths are cut in concrete or other materials such as brick, chipped plywood, or hardwood. The thread cuts into the material over its entire width by cutting grooves. In particular according to the embodiment of claim 13 the material cut out when screwing in the screw can be discharged without any accumulation, the dependent claims reflecting many advantages of further embodiments.
The above content is uploaded by Yueluo or the Internet. If there is any copyright issue, please contact [email protected].
