What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
rivet is a metal rod-shaped part with a cap at one end. During riveting, the rivet uses its own deformation or interference to connect the riveted parts. Commonly used rivets are semi-circular head, flat head, semi-hollow rivets, solid rivets, countersunk head rivets, blind rivets, hollow rivets, etc. At present, rivets are widely used in various backplane products and other stamping products. Since rivets are responsible for the functions of locking, positioning and bearing lateral force in the product, the degree of riveting and vertical have higher requirements. However, in actual production, there are often problems such as the failure of the rivet torsion to meet the requirements, the rivet being skewed by the rivet, the surface of the rivet being cut, the rivet placement being inaccurate and requiring manual repositioning, etc. Very high and very inefficient.
In all kinds of machines and equipment, the various parts are fixed and assembled by bolts and nuts. However, after the machine and equipment are used for a period of time, the bolts and nuts will become loose, which will bring great safety hazards to the use of the machine and equipment. For this reason, when bolts and nuts are used for connection, a spring washer is installed between the nut and the connected part. The spring washer is in the shape of a circular ring, and the ring is not closed, and is sleeved on the bolt. The addition of the spring washer has a certain anti-loosening effect, but it can only prevent the nut from rotating relative to the bolt. In the case of large vibration of the machine, the bolt will rotate relative to the connected part.
Friction type high-strength bolts: suitable for beam and column connections of steel frame structures, solid web beam connections, heavy-duty crane beam connections in industrial plants, braking systems and important structures bearing dynamic loads. Pressure-bearing high-strength bolts: Can be used for shear connections in statically loaded structures that allow a small amount of sliding or in members that are indirectly loaded with dynamic loads. Tensile high-strength bolts: When the bolts are in tension, the fatigue strength is low. Under the action of dynamic load, its bearing capacity is not easy to exceed 0.6P (P is the allowable axial force of the bolt). Therefore, it is only suitable for use under static load. Such as flange butt joints, T-joints, etc. of pressure members.
According to relevant standards, the performance grades of carbon steel and alloy steel bolts are divided into more than 10 grades such as 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, etc. Among them, the bolts of grade 8.8 and above are made of low-carbon alloy steel or medium Carbon steel and heat treatment (quenching, tempering) are generally called high-strength bolts, and the rest are generally called ordinary bolts. The bolt performance grade label consists of two parts of numbers, which represent the nominal tensile strength value and yield ratio of the bolt material respectively. Stainless steel bolts are divided into A1-50, A1-70, A1-80, A2-50, A2-70, A2-80, A3-50, A3-70, A3-80, A4-50, A4-70, A4-80, A5-50, A5-70, A5-80, C1-50, C1-70, C1-110, C4-50, C4-70, C3-80, F1-45, F1- 60. The first letter and number represent the stainless steel group, and the second and third numbers represent 1/10 of the tensile strength. [2]
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