What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Now people often use spring washers to lock nuts and bolts, spring washers, generally stainless steel and carbon steel non-closed spiral washers, under the nut, above the flat washer, increase the friction between the nut and the bolt, used to prevent The loosening of the nut plays a role in preventing vibration and loosening, but it is often due to a radial external tension, which is caused by the tightening axial force generated by the tightening torque, and the phenomenon of open ring expansion occurs, and the hydrogen embrittlement of the spring washer often occurs. The pressure is unevenly applied to the flat washer through the spring washer, and the friction coefficient between the spring washer and the nut and the flat washer is small, resulting in vibration, rotation and relaxation.
Traditional rivet nuts are usually cylindrical, and special tools are required to complete the riveting operation between the workpiece and the sheet, and tools are completely required for locking. And in the actual production process, it is often encountered that there are square holes on the workpiece, and bolts need to be installed in the square holes, especially in the power cabinet and the control cabinet when the workpiece with prefabricated square holes is used as the main frame, due to Due to the special structure of the workpiece, the installation nut can only be inserted from the side, and the installation cannot be completed when the side installation space is limited, which brings inconvenience to the installation.
1. Fixed anchor bolts, also known as short anchor bolts, are poured together with the foundation and used to fix equipment without strong vibration and impact. 2. The movable anchor bolt, also known as the long anchor bolt, is a detachable anchor bolt used for fixing heavy machinery and equipment with strong vibration and impact. 3. Expansion anchor bolts are often used to fix stationary simple equipment or auxiliary equipment. The installation of expansion anchor bolts should meet the following requirements: the distance from the center of the bolt to the edge of the foundation shall not be less than 7 times the diameter of the expansion anchor bolt; the foundation strength of the expansion anchor bolt shall not be less than 10MPa; there shall be no cracks in the drilling holes. The drill bit collides with the steel bars and buried pipes in the foundation; the diameter and depth of the drill hole should match the expansion anchor bolts. 4. The bonding anchor bolt is a kind of anchor bolt commonly used in recent years, and its method and requirements are the same as the expansion anchor anchor bolt. However, when bonding, pay attention to blowing out the debris in the hole, and do not get wet. [1]
There are two types of bolt detection: manual and machine. Manual is the most primitive and the most commonly used consistent detection method. In order to minimize the outflow of defective products, general production enterprise personnel inspect the packaged or shipped products by visual means to exclude defective products (defects include tooth damage, mixed materials, rust, etc.). [2] Another way is automatic machine inspection, mainly magnetic particle inspection. Magnetic particle inspection is to use the interaction between the leakage magnetic field at the defect of the bolt and the magnetic powder, aiming at the difference between the magnetic permeability of the bolts (such as cracks, slag inclusions, mixed materials, etc.) and the magnetic permeability of steel, these materials are discontinuous after magnetization. The magnetic field at the place will be turbulent, and a leakage magnetic field will be generated on the surface of the workpiece where part of the magnetic flux leaks, thereby attracting the magnetic powder to form the magnetic powder accumulation at the defect—magnetic traces. The accumulation of these magnetic powders is observed and explained, and the purpose of rejecting defective products has been achieved.
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