What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Flat washers are generally used in connectors, one of which is soft and the other is hard and brittle. Its main function is to increase the contact area, disperse the pressure, and prevent the soft texture from being crushed. The basic function of the spring of the spring washer is to give a force to the nut after the nut is tightened to increase the friction between the nut and the bolt! The material is 65Mn (spring steel), the heat treatment hardness is HRC44~51HRC, and the surface is oxidized.
In addition, the angle aluminum connection structure itself has structural defects of poor torsional and shear resistance, and many projects use larger insulating glass to meet the requirements of architects, resulting in a larger self-weight. In the event of a natural disaster such as an earthquake that will cause the curtain wall to shake violently, the bolts on the angle aluminum are prone to breakage, and the seismic performance is not good. Especially for the beam with the open structure, since the angle aluminum is installed in the opening cavity of the beam, the inertia moment of the beam is small, and the torsion resistance and shear resistance performance of the force are worse.
The lifting ring screws are generally not surface treated, but according to the requirements, surface treatment such as galvanized passivation and chrome plating can be carried out, and it is specified in GB5267-85. The chemical composition and mechanical properties of the material should be treated immediately after electro-galvanizing. The test methods are specified in GB699. During routine inspection, the grain size test may not be advanced, and the grain size test method shall be in accordance with the provisions of YB27. Thread inspection is performed with thread gauges and smooth limit gauges or universal energy tools.
Many parts on the car need to be rubberized, which can reduce noise, especially the parts related to shock absorption. Nuts are welded on many of these parts to facilitate the installation of other parts on them. The sheet metal is generally relatively thin, and most of them are only one or two millimeters. A through hole is punched, and then the nut is placed in the hole, and then around it. Spot welding is done so that it can be fixed. After spot welding, the periphery of the screw hole on the sheet metal will not be flat due to thermal deformation, which will affect the appearance.
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