What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
As we all know, bolt and nut kits are commonly used fastening parts, but when ordinary bolt fasteners are used in a large number of parts, because the nuts and bolts are engaged by threads, manual or machine tightening is required, and during installation, It is easy to slip, and the bolts need to be operated in both directions, and a pair of bolts and nuts cannot be installed quickly, which reduces the installation efficiency.
Type 1 nut refers to an ordinary hexagonal nut with a nominal height of m ≥ 0.8D. Its type and size should meet the requirements of GB/T6170; while the height of type 2 nut is higher than that of type 1 nut, its type and size should comply with GB/T6170. T6175. There are two purposes to increase the type 2 nut: one is to obtain a relatively inexpensive nut that does not require heat treatment by increasing the height of the nut. Because D≤M16 grade 8 type 1 nuts do not need heat treatment, among grade 8 nuts, only the specifications of D>M16~39 use type 2 nuts. Obviously, type 1 nuts that do not need heat treatment cannot reach grade 9 nuts. Mechanical property requirements. Another purpose of specifying Type 2 nuts is to obtain a more ductile grade 12 nut. As the height of the nut increases, the guaranteed stress index can be achieved at a lower quenching and tempering hardness, so the toughness of the nut is increased. Classified by tooth spacing: standard teeth, regular teeth, fine teeth, very fine teeth and cross teeth. Classification by material: stainless steel hexagon nuts and carbon steel hexagon nuts, copper hexagon nuts, iron hexagon nuts. Classification by thickness: hexagonal thick nuts and hexagonal thin nuts. Classification by usage: hot melt copper nut, hot pressed copper nut, embedded copper nut and ultrasonic copper nut
When using a rivet nut, drill a hole corresponding to the outer diameter of the rivet nut on the thin wall, then place the rivet nut on the bolt of the special rivet gun, push the handle to screw in the rivet nut, and put it into the drilled hole. In the workpiece, squeeze the handle, the rivet nut expands, and the deformed skirt bulges and deforms. At this time, the workpiece is tightened. After riveting, the handle is pulled out, the bolt is released from the rivet nut, and the corresponding screw is screwed into the rivet nut threaded hole. , forming a tight riveted body.
The two combination screws are classified according to the national standard, including GB9074.2, GB9074.3, GB9074.5, etc. GB9074.3 refers to a two-component combination of a cross pan head screw and a foreign lock washer.
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