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.
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 1.7, the air-blown screw machine can be selected.
Embodiments of Guangdong Yueluo Hardware Industry Co., Ltd. are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary, and are intended to be used to explain Guangdong Yueluo Hardware Industry Co., Ltd., and should not be construed as a limitation to Guangdong Yueluo Hardware Industry Co., Ltd.
Half round head rivets are mainly used for riveting occasions with large lateral loads, and are the most widely used. Flat cone head rivets are often used in riveting occasions with strong corrosion such as ship hulls, boiler water tanks, etc. Countersunk head and 1200 countersunk head rivets are mainly used for riveting occasions where the surface must be smooth and the load is not large. Half countersunk head and 1200 half countersunk head rivets are mainly used for riveting occasions where the surface must be smooth and the load is not large. Flat head rivets are used for riveting occasions with general load. Flat head and flat head rivets are mainly used for riveting of metal sheets or non-metallic materials such as leather, canvas and wood. Large flat head rivets are mainly used for riveting of non-metallic materials. Semi-hollow rivets are mainly used for riveting occasions with small loads. Headless rivets are mainly used for riveting of non-metallic materials. Hollow rivets are light in weight and weak in head, and are used for riveting of non-metallic materials with small loads. Tubular rivets are used for riveting of non-metallic materials without load. Nameplate rivets are mainly used for riveting nameplates on machines and equipment.
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