What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
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.
Rivets are nail-shaped objects with a cap on one end: in riveting, the riveted parts are connected by their own deformation or interference. There are many types of rivets, and they are not restricted in form. Commonly used are R-type rivets, fan rivets, blind rivets, tree-shaped rivets Rivets, semi-circular head, flat head, semi-hollow rivets, solid rivets, countersunk head rivets, blind rivets, hollow rivets, these usually use their own deformation to connect the riveted parts, generally less than 8 mm with cold rivets, larger than this size with Hot riveting, but there are exceptions. For example, the nameplate on some locks is riveted by the interference between the rivet and the lock body hole. The rivet pliers are used to cut rivets. The existing rivet pliers have a simple structure and cannot be riveted according to the The user needs to cut a certain length of rivets, and cutting the rivets is time-consuming and labor-intensive, and it is not convenient for people to use.
In the field of mechanical design, there are a large number of connector connection structures that need to be fastened and positioned. As shown in Figure 1, the more common positioning and fastening connection methods at present are that pins 5 and fasteners are used for positioning and fastening, respectively. That is, cylindrical pins or taper pins are used for positioning, and fasteners such as screws or double-ended studs are used for fastening.
The equipment is tightened and fixed by screws during assembly. During high-speed operation, the equipment will generate high-frequency micro-vibration. This micro-vibration can easily lead to loosening of screws, resulting in weak connection of components and easy to cause safety accidents. Fastening is attached great importance. Many companies even directly weld the screw caps after using screws to fasten the components. However, this practice greatly hinders the subsequent maintenance and also seriously affects the maintenance and maintenance of the equipment; The emergence of tightening screws has attracted the attention and favor of enterprises; however, the self-tightening screws I use are mainly imported, and when the trade war begins, the shortage of this autonomous technology will severely limit my defense.
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