What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
There are many types of T-bolts used with pre-embedded chutes, which are used for the connection of external components of pre-embedded chutes embedded in segments, U-beams, building concrete, etc. The fixing of the chute on the forming die. When producing segments and U-shaped beams, the embedded chute is fixed on the forming mold by T-bolts. During the concrete pouring process, the tightening nut is easily covered by concrete. In this way, the concrete on the fastening nut should be removed, but it is difficult to remove the concrete, which will cause inconvenience to the disassembly of the forming mold after the production of the segment and the U-shaped beam.
At present, machinery and equipment have gradually become the main force of work production. Many equipment require frequent maintenance and even replacement of parts during use. During the process of maintenance and replacement, it is inevitable to encounter the problem of screw disassembly and assembly. In the process of disassembly and assembly, it is almost necessary to cooperate with both hands, or because the thread is too long, installation and disassembly are very cumbersome. Especially in the butt installation of flanges, bolts and nuts are used for clamping and fixing at this stage. During use, two hands are required to hold a board, a fixed screw, and a screw nut. This is to prevent the nut from During the turning process, the screw also rotates. When screwing, the wrench should be taken down without interruption, re-selected a good position, and then screw the screw forcefully again, and repeated several times before the screw can be unscrewed. Time and labor costs for maintenance are wasted. At present, there is no screw that is easy to install and remove.
Fig. 1, Fig. 2, and Fig. 3 show that the rivet nut is cut into the required blank from a chemically treated low carbon steel disc, and the blank is placed in the die, and the upper and lower punches are used for shaping to obtain a shaped blank. , and then put the shaped blank in the die, use the punch punch to cold-head out the required brim blank (1) and the deformed skirt (2), and then use the punch punch in the die to continue Cold heading out the brim blank (1) and the deformed skirt (2). Then put the semi-finished material into the concave die and use the punch of the punch to continue to squeeze the threaded hole (3) of the nut tapping skirt, and then put the semi-finished blank into the concave die and use the upper punch and the lower sleeve to drop it. material. There are fish teeth (6) below the brim; the outer side of the lower end of the threaded hole is provided with a chamfer (5); the cross-section of the thread of the inner wall of the threaded hole is an isosceles trapezoid, and the upper bottom of the trapezoid is a concave arc (4), In this way, the riveted object is firmly connected to the rivet nut.
The process factors that affect the quality of high-strength fasteners include steel design, spheroidizing annealing, peeling and dephosphorization, drawing, cold heading, thread processing, heat treatment, etc., and sometimes the superposition of various factors.
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