What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Spring mattresses and spring seat cushions are modern and commonly used furniture products with better performance, and their cushion cores are composed of springs. It makes full use of the advantages of good spring elasticity, good support, strong air permeability and durability. The traditional spring pad is a spring with a thicker wire diameter, which is connected and fixed by steel wires, and has high hardness. Most of the elders of the older generation often use linked spring beds, but if they sleep in a fixed position for a long time or are accustomed to sitting on the side and corners of the bed, or flip the mattress irregularly, it is easy to cause depression and elastic fatigue.
Generally, the countersunk head is used in places where the surface is required to be smooth without protrusions, because the countersunk head can be screwed into the part. Round heads can also be screwed into parts. The tightening force of the square head can be larger, but the size is large. In addition, in order to meet the needs of locking after installation, there are holes in the head and holes in the rod. These holes can prevent the bolts from loosening when they are vibrated. Some bolts without threads should be made thin, called thin-waisted bolts. This kind of bolt is beneficial to the connection under variable force. There are special high-strength bolts on the steel structure, the head will be larger, and the size will also change. In addition, there are special uses: for T-slot bolts, which are most used on machine tool fixtures, with special shapes, and both sides of the head should be cut off. Anchor bolts, used for machine and ground connection and fixing, come in many shapes. U-bolts, as previously described. and many more. There are also special studs for welding. One end has a thread and the other end is not. It can be welded to the part, and the other side can directly screw the nut.
Commonly used standards are broadcast. For hexagonal nuts, the commonly used standards are: GB52, GB6170, GB6172 and DIN934. The main differences between them are: the thickness of GB6170 is thicker than that of GB52, GB6172 and DIN934, commonly known as thick screw cap. 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.
In the installation of the external electrical components of the high-voltage electrical box, generally, the whole aluminum alloy profile with a T-slot is laid on the shell of the high-voltage electrical box, and then the upper nut is placed in the T-slot, and the bottom of the square nut is provided with a spring , When installing the electrical components, align the mounting holes with the screw holes of the square nut, then screw and tighten the screws to achieve the installation of electrical components. The biggest defect in the above installation process is that the alignment of the mounting hole and the screw hole is not very convenient, and the spring at the bottom of the square nut is easy to be missing. Once the spring is missing or damaged, the square nut cannot be effectively positioned in the T-slot. It makes the alignment of the mounting hole and the screw hole more difficult. Third, the above-mentioned connection and fixing method itself is not particularly ideal.
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