What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
With the rapid development of electronic technology, the integration of circuit boards is getting higher and higher, and the number of layers of circuit boards is increasing. Press-fit and fix to ensure accurate alignment during riveting and pressing. The rivets used on PCB boards are basically brass rivets. When riveting and pressing multi-layer PCB boards, metal chips are prone to appear, inner layer short circuits or foreign objects between layers, and because of the brass rivets With higher hardness and larger wall thickness, the riveted area of the PCB is thicker than the non-riveted area, which is easy to cause damage to the middle steel plate of the auxiliary tool. At the same time, the protruding rivets hinder the free expansion of the copper foil, which is easy to produce copper foil. wrinkling phenomenon. Now there are improved plastic rivets used to manufacture multi-layer PCB boards. The advantage is that no metal debris is generated, and at the same time, the tool steel plate is not damaged to the greatest extent. However, the existing plastic rivets are insufficient due to the inherent strength of plastics. When the PCB board is riveted and pressed, it is easy to deform, and the positioning is inaccurate, resulting in dislocation between layers, resulting in poor improvement of the product defect rate.
Nut fasteners are used in various industries with connection and fastening requirements, such as vehicles, construction machinery, agricultural machinery, manufacturing machinery, etc. For large construction machinery or construction vehicles, due to the harsh working environment and the action of heavy loads, the nut fasteners on it are subjected to vibration and load impact in all directions, which makes the nut easier to loosen, resulting in tightening. The function of the device is reduced or even failed. cause a great safety hazard.
In the existing life, repair parts are often used to repair the cassettes with damaged screw holes, and the screw holes on the repair parts are used instead of the original damaged cassette screw holes. However, in the prior art (application number: 201520948368.3), the restoration is fixed by rotating the support of the restoration, which is often inconvenient due to the small space of the cassette. In addition, the set screw in the prior art mainly fastens the object through the end of the screw without threaded holes, which makes it difficult to install external screws. Based on this, a method of extruding the support through a set screw with screw installation holes and tightening the repair piece, and then installing the screw on the set screw, will facilitate the quick installation and use of the repair piece.
The flat gasket product is an accessory on the high-speed rail backing plate. The product requires two planes to be flat, the shape and size of the inner hole are accurate, and there are no casting defects (such as air holes, shrinkage holes, sand holes, etc.), and the casting material requires GB/T450-10 . Due to the light weight and large demand of flat gaskets, if they are produced by ordinary sand casting process, the castings are prone to deformation, sand holes, air holes and other casting defects, and the molding area is large, the production efficiency is low, and the production tasks are difficult to complete.
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