What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Bolts refer specifically to screws with larger diameters and may also have no heads, such as stud bolts. In general, it is not called a stud bolt but a stud stud. The most common form of stud is threaded at both ends and a polished rod in the middle. The most typical use: anchor bolts, or places similar to anchor bolts, thicker connections, when ordinary bolts cannot be used.
Comparing the physical properties of stainless steel and carbon steel, the density of carbon steel is slightly higher than that of ferritic and martensitic stainless steel, but slightly lower than that of austenitic stainless steel; the resistivity is based on carbon steel, ferritic, martensitic and The order of austenitic stainless steel is increasing; the order of linear expansion coefficient is similar, austenitic stainless steel is the highest and carbon steel is the smallest; carbon steel, ferritic and martensitic stainless steel are magnetic, austenitic stainless steel is non-magnetic, But its cold work hardening will generate magnetism when it is transformed into intensite, and heat treatment method can be used to eliminate this martensitic structure and restore its non-magnetic properties. Compared with carbon steel, austenitic stainless steel has the following characteristics: 1) High electronegative rate, which is about 5 times that of carbon steel. 2) The large coefficient of linear expansion is 40% larger than that of carbon steel, and with the increase of temperature, the value of the coefficient of linear expansion of stainless steel screws increases accordingly. 3) Low thermal conductivity, about 1/3 of carbon steel.
The marking format of the thread mark is: Thread code - thread tolerance zone code (pitch diameter, top diameter) - screw length l) Tolerance zone code is represented by numbers plus letters (inner thread with uppercase letters, external thread with lowercase letters) , such as 7H, 6g, etc., it should be specially pointed out that 7H, 6g, etc. represent thread tolerance, while H7, g6 represent cylinder tolerance code. 2) The length of rotation is specified as short (represented by S), medium (represented by N), and long (represented by L). In general, the thread engagement length is not marked, and the thread tolerance zone is determined by the medium engagement length (N). If necessary, add the screw length code S or L, such as M20-5g6g-L. When special needs are required, the value of the screwing length can be indicated, such as M20-5g6g-30.
Pull rivets, * marked as blind rivets, are based on the principle of Hooke's law. After the two joints are clamped with special equipment for pull rivets, the metal of the ring-shaped collar is squeezed and filled to the point where there are many rivets. In the groove of the bolt column of the annular groove, a fastening method that tightly combines the collar and the bolt column. A riveting machine is a mechanical device that uses rivets to riveted items together in batches. The riveting machine is mainly assembled by rotation and pressure. The riveting machine is mainly used in the occasions where rivet riveting is required. The common specifications and models include pneumatic, hydraulic and electric, single-head and double-head.
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