What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
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.
At the beginning of the quality inspection process broadcast, we ordered the cross recessed screw and screw wire material into our production screw industry. For manufacturers in the screw industry, we must first detect the wire diameter of the screw wire and the material of the screw. Generally, the wire diameter of the screw is measured by a caliper and a measuring wire. Diameter size, whether it is the same as the size ordered by yourself. After testing these, it is the testing in the production process, starting from the head of the screw, to determine the size of the head, the opposite side of the head, the diagonal angle, the depth of the cross groove, the tolerance range of the screw, and so on. These are checked with calipers. In the inspection of all aspects when rolling teeth, the main thing is whether the thread can pass the pass and stop gauge, and whether the screw thread can pass the gauge and stop. Next is the electroplating measurement problem. After electroplating, whether it meets the requirements of environmental protection and whether it can pass the time required by the salt spray. Tools include environmental testing machines and salt spray testing machines. In short, in the production and sales process of cross recessed screws, there must be necessary tools to detect the quality of screws. The summary should be summarized as follows: calipers, hardness testers, salt spray machines, environmental testing machines, pass and stop gauges, etc. .
Fasteners are widely used in nuclear power plant safety systems and equipment, and undertake the functions of component connection, pressure sealing box support and fixation, and their quality and performance play an important role in nuclear power plant safety systems and equipment performing nuclear safety functions. None of the special fasteners for nuclear power in the prior art have protective sleeves, which cannot protect the exposed part of the bolt shank. In order to solve the above difficulties, it is necessary to develop a fastener stud nut washer set that can protect the exposed part of the bolt shank.
Most electrical appliance manufacturers only require the size and riveting gap to be tested for riveted contact components. There is no clear requirement for riveting strength. Only a few manufacturers perform torsion testing on riveting strength. The torque detection method is as follows: use a saw blade to open a one-shaped groove on the rivet head of the riveted contact element, and then insert a torque wrench into the one-shaped open groove to rotate, and measure the torque value. Because most of the electrical contacts are made of copper-silver alloy, the strength is low, and it is easy to slip during the test, and when a saw blade is used to open the one-shaped groove, the width and depth cannot be accurately positioned, so the measured value fluctuates greatly. , has always been an unsolvable technical problem in the industry.
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