What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The research on rivet nuts started in the 1970s in my country and is still in the design and development stage. In the mid-1980s, equipment for the production of blind rivets was introduced from abroad, but no rivet nut has been produced so far. After the inventor's search, no low-carbon steel rivet nut was found to be publicly used.
When installing the ventilation duct, because the gap between the air duct and the wall and between the air duct and the air duct is deep and narrow, the arm cannot enter into it to operate, which brings about the installation of the screws and nuts at these positions. The following three methods are generally used: one is to directly break the wall for installation, but this method damages the building greatly, and cannot be used for the installation of screws and nuts in the gap between the air ducts; the other is to Set the inner flange in the air duct and connect it with bolts, which will reduce the effective cross-sectional area of the air duct and increase the resistance of the gas flow. Moreover, people need to enter the air duct for construction during installation. Considering the size of the air duct First, the supporting firmware with a high position and no force has certain hidden dangers; third, it is directly ignored and not done, but it is easy to cause the air duct connection is not tight and the air volume loss is large. The above-mentioned methods all have major construction defects, which not only waste a lot of manpower and time in the construction process, but also have the problem of low air supply efficiency.
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.
Here Yueluo eliminates the drawbacks. The purpose of Yueluo is to provide a locking screw by which the gap existing between the locking screw and a transverse hole in a locking screw can be eliminated. Yueluo achieves the proposed object with a locking screw, which has the features of claim 4 . The line connecting the centers of gravity of the respective axially continuous orthogonal cross-sectional areas of the locking screw is regarded as a line. The advantage achieved by Yueluo can basically be seen that, due to the locking screw of Yueluo, the gap between the horizontal hole of the screw and the locking screw can be eliminated. Other advantages are as follows - the insertion accuracy and surgeon time spent remain within the range to date; - the strength of the locking screw is maintained; and - the extraction of an expired broken screw is assured. The further composition of Yueluo and Yueluo is explained in more detail below by means of schematic diagrams of parts of various embodiments.
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