What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
(1) The screw-in performance test is to screw the self-tapping locking screw sample into the test plate until one complete thread completely passes the test without breaking. (2) The destructive torque test is to clamp the stem of the self-tapping locking screw specimen in a thread mold or other device that matches the screw thread, and uses a calibrated torque-measuring device to measure the screw. Torque is applied until fracture, which should not occur in the clamped threaded portion. (3) Carry out a tensile test on the screw sample to check the minimum tensile load for failure. The fracture should be within the length of the rod or the unthreaded thread, and should not occur at the junction of the nail head and the rod. Before the sample breaks, it should be It can reach the minimum tensile load specified by the corresponding performance class. (4) Hydrogen embrittlement is a problem that must be strictly paid attention to in the surface treatment process of self-tapping locking screws. In the pickling process, the screw is stirred in dilute hydrochloric acid, and the amount of hydrogen absorbed by the pickling steel increases linearly with the square root of time and reaches the saturation value. Less than 100%, a large number of hydrogen atoms will be produced, which will be attached to the surface of the screw, resulting in hydrogen infiltration, and the steel will become brittle due to the absorption of hydrogen. The self-tapping locking screw takes 6~8h to drive hydrogen, and the temperature is 160~200℃ (phosphating) and 200~240℃ (electroplating). However, in the production process, the hydrogen drive time should be determined according to many production conditions such as core hardness, surface roughness, electroplating time, coating thickness, pickling time, and acid concentration. It is best to do it before passivation and just after electroplating.
Rivets are mostly used for fixed riveting and movable riveting between parts. The rivets used for movable riveting are mostly cylindrical, and there is no size limit for riveted parts, which is easy to cause parts to be squeezed and deformed during riveting. For example, The parts are inserted into the parts for active riveting. When riveting, the riveting force can easily cause the parts to clamp the parts, which in turn causes difficulty in the movement of the parts and the parts, high operating force and noise problems, and the parts are easily damaged.
By adopting the above technical solution, the setting of the pin cap allows the user to conveniently drive the pin into the pin hole of the workpiece by using a hammer and other power-assisted equipment. Pin hole, the plane of the top contact body relative to the pin cap will collide with the plane where the pin hole is located, the convex body and the pin hole are tightly squeezed, and the pin cannot fall off.
Yueluo Company adopts the following technical solutions: fasteners for preventing nuts from falling off, including bolts and nuts, the nuts are provided with screw holes, the screw holes are provided with internal threads, the bolts are provided with M grooves along its axial direction, M ≥1; There is an arc-shaped notch on the screw hole of the nut, and there are N V-shaped tooth grooves along the axial direction of the nut in the arc-shaped notch, N≥2; a locking strip is placed in the groove, and the locking The bar includes a locking bar body and a V-shaped locking tooth, the width of the locking bar body is the same as the width of the groove, the V-shaped locking tooth is located on one side of the locking bar body, and the V-shaped locking tooth is engaged with the V-shaped locking tooth.
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