What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The tooling for screw standard parts provided by Yueluo Guangdong Yueluo Hardware Industry Co., Ltd. mainly solves the problems of low manual operation matching efficiency, wrong specifications of screw standard parts, and easy falling of screw standard parts into the product when assembling screws in the prior art. . The specific technical solutions of Guangdong Yueluo Hardware Industry Co., Ltd. are as follows. The screw standard parts supporting tooling includes a stud sleeve hole plate, a gasket sleeve hole plate and a nut sleeve hole plate with matching structure; the stud sleeve hole plate There is at least one stud hole matching with the assembled stud structure, at least one gasket hole matching with the assembled gasket structure is arranged on the gasket sleeve hole plate, and the nut sleeve hole plate is provided with at least one gasket hole matching with the assembled gasket structure. At least one nut hole matched with the assembled nut structure; the number of stud holes, gasket holes and nut holes are equal. The above-mentioned stud sleeve hole plate is provided with a positioning device, and the gasket sleeve hole plate is provided with a matching positioning hole; or the gasket sleeve hole plate is provided with a positioning device, and the stud sleeve hole plate is provided with a matching positioning hole. The above stud holes are through holes; the nut holes are blind holes. Forty to one hundred and fifty stud holes are arranged on the stud sleeve hole plate. The above-mentioned positioning device is a positioning plate and/or a positioning column. The advantage of Guangdong Yueluo Hardware Industry Co., Ltd. is that the matching tooling for screw standard parts improves the matching quality of screw standard parts, effectively prevents screw standard parts from falling into the product easily and screw specifications are wrong; it simplifies the matching difficulty of screw standard parts and improves assembly efficiency. . The screw standard parts supporting tooling can be processed differently according to different screw standard parts specifications, and the applicability is very wide.
M4 grounding screw used to fix the grounding wire on household appliances and other equipment, the stud is cylindrical, and the thread is perpendicular to the end (section) surface. However, the screw holes on the equipment all have tapping guide grooves for sinking and guiding due to the manufacturing process requirements. When fixing the ground wire, if the screw is not positioned accurately (the screw is inclined), the screw is pressed down hard, which is easy to cause the screw and the screw. The screw hole bites the teeth, and after biting the teeth, it is easy to cause the screw to loosen or fall off, posing a safety hazard.
In the prior art, there are two ways to feed the screws of the locking screw machine, the air blowing type and the air suction type. The air suction type is suitable for relatively small screws. If the screw size is larger than M2, smaller than M5, and the length-diameter ratio is larger than 1.4, the air-blown screw machine can be selected.
(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.
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