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.
The classification of the second combination screw is divided according to the material of the screw wire and the hardness index of the screw wire. Generally, the two combination screws are divided into stainless steel and iron, and stainless steel is divided into stainless steel 201, stainless steel 304 and stainless steel 316. Iron is divided into three types: low carbon steel, medium carbon steel, and high carbon steel. Carbon steel combination screws refer to iron combination screws. Generally, iron combination screws are classified into grades 4.8, 8.8, 10.9, and 12.9. But in the market, the combination screws of grade 10.9 and grade 12.9 are rarely used, so we won't talk about it here. And the two combination screws on the market are more commonly used combination screws of grade 4.8 and 8.8. 4.8 grade combination screws are generally made of 1010A screw wire rods. After the screw wire rods are beaten into screws, they are combined with spring flat washers. After production, this 4.8 grade combination screw does not need to be hardened. Its hardness can reach 4.8. The 8.8 grade combination screw is generally made of 10B21 screw wire. After the screw wire is punched into a screw, it is equipped with a spring washer and a flat washer, and the three pieces can be combined and rubbed by an automatic spring-flat washer machine. Fasten the spring-flat washer combination on the screw, and the spring-flat washer will not fall off. After the combination screw is produced, it needs to be hardened to make the hardness reach 8.8. After the hardness reaches 8.8, we need to take it for electroplating. In order to prevent hydrogen embrittlement of the spring washer in the 8.8-level combination screw with added hardness, it is easy to break. In this way, it is necessary to carry out hydrogen removal treatment on the hardened combined screws, and the electroplating can only be done after the hydrogen removal.
For common screw belts, please refer to the Central Taiwan Announcement No. 327449 on February 21, 1998, Screw Belts (2), which includes a main body with multiple grooves on the side of the main body for the purpose of locking screw tools to drive the belt. A toggler; and a plurality of nail grooves are arranged on the nail belt so that the screw planting is arranged in an arrangement, and the nail grooves are all provided with through holes, and the through holes extend downward with a ring to form a support portion for the screws; and the It is surrounded and provided with a plurality of cutting grooves, which is beneficial for the screw to be rotated through the nail groove; and it is characterized in that the nail groove is located on the inner wall surface of the surrounding and is provided with a plurality of lobes, and these lobes are implanted in the screw. In the nail groove, the leaflet supports the screw, so that the screws with different outer diameters are fully supported and positioned by the leaflet; and/or the upper part of the leaflet is inclined or curved, so that a depression is formed above the ring to support the screw The arc surface or tapered surface of the neck can make the screw more stable to be supported.
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.
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