What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
T-slot bolts refer to the bolts installed in the T-slot. The installation process of T-slot bolts is usually as follows. When the T-slot (generally refers to the T-slot aluminum alloy profile) is set horizontally, the bolt The bolt head is placed in the T-slot in the horizontal direction, the bolt shaft is facing outward, and then the bolt is rotated 90 degrees axially, the bolt head becomes vertical and will not come out of the T-slot, and then install the mounting hole of the object Align the bolt rod and insert it and screw the nut on the bolt rod. During the tightening process of the nut, if the thread gap is small or the thread is damaged or there is dirt, the bolt will often rotate, and the rotation angle of the bolt is uncontrollable and impossible. Observe that when the rotation angle of the bolt is in the range of about 90 degrees, the bolt is in a state of being released from the T-shaped groove at any time. Even if the nut is tightened, the installation of the installation object is invalid and unreliable, and there is a serious safety hazard. , the actual situation is that when the rotation angle of the bolt exceeds 20-30 degrees, the installation of the installation object is already unreliable.
As a standard part, it should have its own general specifications. For hexagonal nuts, the commonly used standards are: GB52, GB6170, GB6172 and DIN934. The main differences between them are: GB6170 is thicker than GB52, GB6172 and DIN934. Thick from DIN934, commonly known as thick nut. The other is the difference between the opposite sides, the opposite sides of DIN934, GB6170 and GB6172 in the M8 nut series are 13MM smaller than the opposite side 14MM of GB52, and the opposite sides of M10 nuts, DIN934 and GB52 are 17MM. The opposite side of GB6170 and GB6172 should be 1MM larger, M12 nut, DIN934, GB52's opposite side is 19MM larger than GB6170 and GB6172's opposite side 18MM is 1MM larger. For M14 nuts, the opposite side of DIN934 and GB52 is 22MM, which is 1MM larger than the opposite side of GB6170 and GB6172, which is 21MM. The other is the M22 nut. The opposite side of DIN934 and GB52 is 32MM, which is 2MM smaller than the opposite side of GB6170 and GB6172, which is 34MM. (Besides the thickness of GB6170 and GB6172 are the same, the width of the opposite side is exactly the same) The rest of the specifications can be used in general without considering the thickness.
As my digital TV technology becomes more and more mature, more and more people with digital-to-analog signal conversion function enter people's lives. Therefore, the number of production and processing is also increasing day by day. There are many requirements for the form, reliability and cost of PCB fixing screws in production. One of the existing fixing methods is to fix by means of bolts and nuts. The operation steps are to place the PCB board on the inner threaded copper column connected to the casing, and pass through the bolts with fine teeth. Screw holes on the PCB board, and then fix them on the copper posts with nuts. The connection method of this solution is reliable, but its manufacturing cost is high, and the copper column and the metal shell need to be screwed together, resulting in low production efficiency and high cost. In addition, there is also a common way that the PCB is supported by a plastic column, and the self-tapping screw is passed through the screw hole on the PCB board, and the PCB board and the metal bottom shell are connected by the self-tapping thread on the screw. The main disadvantage of this solution is that after the screw is fixed on the metal shell, the screw head is exposed at the bottom of the machine. If the user is not careful during use, the hand scratching phenomenon will occur, which will bring changes and harm to the user's use. . And when the machine slides on the desktop, if the screw head is too exposed, it will scratch the desktop. Therefore, how to provide a PCB fixing method with convenient operation, reliable connection and low production cost is a technical problem to be solved urgently in the industry.
At present, more rivets are used on car tires. Due to the long-term bumps of the car, traditional equipment is prone to loosening during the use process, which affects safety. The above problems need to be improved on traditional equipment, so how to design a Rivets on car tires, this becomes a problem we need to solve.
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