What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Traditionally used for plastic fastening screws, most of the thread designs are self-tapping threads, but for different plastic types, the self-tapping threads also have many different classifications, such as PT profile, Plastite series, Remform profile, etc. The structural parameters and manufacturing process of these threads are inconsistent, or require different main molds and wires. Therefore, to find a plastic screw that is universally applicable to various plastic types, has a single pressing structure, low-cost and simple manufacturing process, especially its special self-tapping thread, is an important issue that needs to be solved urgently at present. question. The purpose of Yueluo Yueluo Guangdong Yueluo Hardware Industry Co., Ltd. is to propose a plastic screw to solve the screw fastening problem that is generally applicable to different plastics. The purpose of Yueluo Guangdong Yueluo Hardware Industry Co., Ltd. is to realize a kind of plastic screw through the following technical scheme, it is characterized in that, the thread of the screw is composed of asymmetric threads with a profile angle of 30°, and the threads are The bottom surface of the connection between them is an arc surface. Yueluo preferably, the asymmetrical thread has a forward thread angle greater than the reverse thread angle, and the sum of the two-direction thread angles is 30°. Yueluo further preferred that the tooth profile angle of the asymmetrical thread is 20 degrees in the direction of installation, and the tooth profile angle in the reverse direction is 12 degrees. Yueluo Guangdong Yueluo Hardware Industry Co., Ltd.'s application of plastic screws, through the improvement of special thread structure, reduces the radial pressure and installation torque when the screw is installed, reduces the damage to the plastic hole; and increases the pull-out resistance of the screw force, it is not easy to appear loose assembly. At the same time, the design of the bottom surface of the connection between the threads of the arc optimizes the flow of the material of the installation object, which improves the integrity of the installation connection.
At present, in the era of industrialization, rivets used in specific occasions, automobiles, and aviation industries can only rely on professional tools and equipment to complete the riveting method.
At present, most of the cylindrical pin press-fitting is to put the product into the positioning position of the lower die first, and then take a cylindrical pin and put it into a cylindrical pin positioning hole that is concentric and perpendicular to the hole in which the product is pressed, or put it on the product. , the pin needs to have a positioning guide; or it is fixed on the top of the indenter so that it will not fall, and then the press is completed. In fact, it is difficult to press the small cylindrical pins. To ensure the good quality of the product, it is required to locate accurately, to ensure that the cylindrical pins are concentric and vertical, and to put the cylindrical pins one by one. It is very easy for workers to produce. Fatigue and low efficiency, product quality control is affected by many human factors, resulting in unstable product quality and certain safety hazards in work. On the other hand, in some production lines, the cost of the press-in cylindrical pins is relatively expensive, such as finger cylinders and moving mechanisms, which will put a lot of cost pressure on the equipment investment of small and micro enterprises.
Reference standard GB 90 Fastener acceptance inspection, marking and packaging GB 196 Basic dimensions of ordinary threads (1～600mm in diameter) GB 197 Tolerance and fit of ordinary threads (1～355mm in diameter) GB 230 Test method for Rockwell hardness of metals GB 699 High-quality carbon Plain structural steel technical conditions GB 1237 Marking method of fasteners GB 5267 Electroplating layer of threaded fasteners GB6394 Determination of average grain size of metals
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