What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The core rivet is another type of single-sided riveting. When riveting, the head of the rivet is hit with a hammer to expose the core, so that it is flush with the end face of the nail head, that is, the riveting operation is completed, which is very convenient, especially suitable for inconvenient Riveting occasions using ordinary rivets (which must be riveted from both sides) or blind rivets (lack of a rivet gun). Usually use flat head rivets, countersunk head rivets are suitable for occasions where smooth riveting is required on the surface.
The most important link in the development and design of fasteners is quality control. There are several major points from the feed to the finished product shipment, and these major points have different inspection methods. First of all, the feed is related to appearance, size, elements, performance, detection of harmful substances, etc.; the process is more about appearance, size, percussion test, forging flow line; heat treatment is more about appearance, hardness, torque, tension , metallography, etc.; the surface treatment is more about some hydrogen embrittlement tests, coatings, salt spray, etc., including a detection of harmful substances in shipments. In size and appearance inspection, the common ones are quadratic element, contour measuring instrument, three-coordinate measuring instrument, image sorting machine (this is a full selection machine); in mechanical and chemical inspection, there are mainly hardness machines (Rockwell and Vickers). ), tensile machine, metallographic microscope; in material testing, there is a spectrum analyzer and a salt spray testing machine.
However, due to a radial external tension, the external tension is caused by the tightening axial force generated by the tightening torque, and the phenomenon of open ring expansion occurs, and the spring washer often breaks due to hydrogen embrittlement. The nut exerts uneven pressure on the flat washer through the spring washer. And the friction coefficient between the spring washer and the nut and the flat washer is very small, and the phenomenon of vibration, rotation and relaxation occurs.
R-type plastic rivets, also known as expansion rivets, are composed of plastic sub-nails and female buckles. It is not necessary to use installation tools during installation, place the installation base in the smooth hole, and then press the head, the specially designed feet expand and stretch after being stressed, and are firmly locked on the installation surface. It is often used to connect plastic shells, lightweight boards, insulating materials, circuit boards, or any other thin, light-weight materials. It is beautiful, practical, and easy to use.
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