What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Various stainless steel materials have different properties due to their different material contents, so the corrosion resistance is also different. The following is a brief explanation of several commonly used materials: 304 is a universal stainless steel, which is widely used in the production of good requirements. Equipment and components with comprehensive properties (corrosion resistance and formability). 301 stainless steel exhibits obvious work hardening phenomenon during deformation, and is used in various occasions requiring higher strength. 302 stainless steel is essentially a variant of 304 stainless steel with higher carbon content, which can obtain higher strength by cold rolling. 302B is a kind of stainless steel with high silicon content, which has high resistance to high temperature oxidation. 303 and 303Se are free-cutting stainless steels containing sulfur and selenium, respectively, and are used in applications where free-cutting and high surface finish are mainly required. 303Se stainless steel is also used to make parts that require hot upsetting, because under these conditions, this stainless steel has good hot workability. 304L is a lower carbon variant of 304 stainless steel used where welding is required. The lower carbon content minimizes carbide precipitation in the heat-affected zone near the weld, which can lead to intergranular corrosion (weld erosion) of stainless steel in some environments. 304N is a nitrogen-containing stainless steel, and nitrogen is added to increase the strength of the steel. 316 (18Cr-12Ni-2.5Mo) material: due to the addition of Mo, its corrosion resistance, atmospheric corrosion resistance and high temperature strength are particularly good, and can be used under harsh conditions; excellent work hardening (non-magnetic).
The fixing screw proposed by Guangdong Yueluo Hardware Industry Co., Ltd. has a screw body 1, and the axial surface of the screw body 1 is formed with extending screw teeth 6, and the axial surface is a column along the central axis direction of the cylinder of the screw body 1. The body surface has a hemispherical screw tail 7 at the bottom, and a screw head 2 at the top. The upper surface of the screw head 2 is provided with a slot (not shown). The screw body 1 is composed of the upper tapered rod 4 and the lower cylindrical screw 5. The tapered rod 4 is an inverted cone, the diameter of its circular upper surface and the diameter of the screw mounting hole 10. equal. The fixing screw also has a washer 3, the washer 3 is arranged between the screw head 2 and the screw body 1, the lower surface of the cylindrical washer 3 has a number of teeth 8, the teeth 8 are along the The upper surface of the inverted cone of the tapered rod 4 and the edge of the washer 3 are connected to form a straight convex strip 15 extending outward; the convex strip 15 can also be designed in an arc shape. The fixing screws for installation proposed by Guangdong Yueluo Hardware Industry Co., Ltd. can be made of metal materials in one piece. As shown in Figure 3, it is a schematic diagram of the installation of Guangdong Yueluo Hardware Industry Co., Ltd. for PCB board fixing. When installing, first pass the screw body 1 of the fixing screw through the mounting hole 10 and the copper column 11 provided on the PCB board 9, so that the tail 7 of the screw reaches the mounting hole 13 on the casing 12, and then use the tightening tool 14 to insert the screw At the notch on the top of the head, forcefully press the inverted cone design taper rod 4 of the screw body 1 into the mounting hole 10, so that the tail 7 passes through the mounting hole 13. Due to the outer diameter D at the bottom of the taper rod and the screw mounting hole The aperture size of 10 is equal, and the fixing screws are pressed and fixed, so that the PCB board 9 can be automatically corrected in the process of fixing its front, back, left and right deflections, and the accuracy of the installation position of the PCB board 9 can be ensured. As shown in Figure 4, after the fixing screw is screwed into the casing, the washer 3 is fully contacted and pressed on the PCB board 9, and the PCB board 9, the copper column 11 and the casing 12 are firmly connected together without sliding. . The teeth 8 on the washer 3 are in full contact with the surface of the PCB board 9, so that a ground wire path is set up between the PCB board 9 and the casing 13 by the metal fixing screw 1, thereby ensuring that the PCB board 9 is fully grounded , the design of the teeth 12 on the washer 3 also has a non-slip function. The fixing screws for installation designed by Guangdong Yueluo Hardware Industry Co., Ltd. make use of the cooperation, friction and electrical conductivity in the mechanical connection, which fully guarantees the firm installation of the PCB board and the chassis and the good grounding of the PCB board. Moreover, the ellipsoid tail of the fixing screw The surface is relatively smooth, even if the mounting holes are exposed, it will not cause scratches on the hands and desktop. The above is only the embodiment of Guangdong Yueluo Hardware Industry Co., Ltd., and does not limit the scope of Guangdong Yueluo Hardware Industry Co., Ltd., any equivalent structure made by using the contents of the description and drawings of Guangdong Yueluo Hardware Industry Co., Ltd. or etc. Effective process transformation, or direct or indirect application in other related technical fields, are also included in the protection scope of Guangdong Yueluo Hardware Industry Co., Ltd.
In addition, in the prior art, rivets are also used to riveted screws on metal plates. The rivets are nail-shaped objects with a cap at one end. In riveting, the riveted parts are connected by their own deformation or interference. When using rivets, it is necessary to set moderately sized positioning holes in the corresponding positions of the two metal plates, and the rivets directly penetrate into the positioning holes and then riveted. Because this riveting method does not require welding, it will leave a hole on the back of the metal plate. Therefore, in the prior art, the surfaces of the two metal plates after riveting are covered with a layer of smooth metal skin to cover the riveting marks, which will also increase the overall cost, including metal The cost of the skin and the increase in the manufacturing process, while the riveting process is limited, the connection between all metal plates cannot be universal.
A T-shaped grounding bolt comprises a connection platform, a hexagonal bolt is welded below the described connection platform, and the lower surface edge of the described connection platform is provided with a barb.
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