What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
nut is a connecting nut, a part that is screwed together with a bolt or connecting screw for fastening, and a component that must be used in all production and manufacturing machinery. There are many kinds of nuts, we commonly have standard, German standard, British standard, American standard, Japanese standard nuts. According to different materials, nuts are divided into carbon steel, high strength, stainless steel, plastic steel and other types. According to the product attributes, the corresponding standard numbers are divided into ordinary, non-standard, standard, new standard, American system, British system, and German standard. Different sizes, unequal threads are divided into different specifications. The general standard and German standard are represented by M, and the American system and the British system are represented by fractions or #. The specification nut is a part that tightly connects the mechanical equipment. Only through the inner thread, the same specification nut and screw can be connected together. The anti-loosening of the screw has always been the intersection of people's attention. The anti-loosening of the nut is of great significance to the current life, because it directly affects the service life of the machine. Therefore, it is also very important for people's life safety. Technicians can achieve the anti-feeding of the nut by changing the material of the nut and increasing the method of tightening the nut, but these methods cannot fundamentally solve the problem, and increase the tightening nut while taking up more space.
The maximum unscrewing torque of the lock nut is affected by many factors. For the research on the low-cycle fatigue performance of the lock nut, the pitch diameter of the thread, the helix angle and the bevel angle of the thread remain unchanged. Only the maximum elastic restoring force FNmax and the equivalent friction angle ρe of the thread piece will appear to a certain extent after repeated use. Change. Therefore, it is only necessary to analyze the variation law of the maximum unscrewing moment when the lock nut is subjected to cyclic load from these two aspects.
As a commonly used data communication device, connectors are widely used in computers and TVs. Because common connectors such as D-SUB and DVI are composed of a male seat and a female seat, the iron shell of the male seat and the female seat is The corresponding position is provided with holes, the holes of the male seat are connected with rivets, and the holes of the female seat are correspondingly provided with screws for fixing. After the male seat and the female seat are connected, tighten the screws so that the male seat and the female seat are tightly connected together. When assembling on a computer or a TV, the rivet has a fixed assembly direction, and the fixation of the rivet direction is very important for assembly. However, there is no anti-rotation device on the iron shell hole connected with the rivet on the existing connector, and the rivet cannot be positioned during the assembly process, and it is easy to rotate and dislocate. production 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 14 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.
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