What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Screws are a common fastener widely used in machinery, electrical appliances and buildings. The general material is metal or plastic, it is cylindrical, and the grooves engraved on the surface are called threads. Due to the different units of measurement, the representation methods of various threads are also different. For example, M16-2X60 represents a metric thread. His specific meaning is that the nominal diameter of the screw is 16MM, the pitch is 2MM, and the length is 60MM. Another example: 1/4—20X3/4 means the inch thread, what he specifically means is the nominal diameter of the screw It is 1/4 inch (one inch = 25.4MM), there are 20 teeth on one inch, and the length is 3/4 inch. In addition, if you want to express American screws, UNC and UNF are usually added to the back of the British screws to distinguish between American coarse teeth or American fine teeth.
At present, injection molding screws are widely used in various electronic and automotive components, including a body, the middle of which is provided with a through hole 3, the body head 1 has a hexagonal cross-section, and the tail 2 is provided with screw teeth. When in use, the middle through hole 3 of the main body will first put the wire harness, and then fix it by injection molding from the head I, and the threads of the tail 11 should be connected and installed with other components. Because the head I of the main body is hexagonal, the torque provided after injection molding is insufficient. Therefore, after the external thread is installed and connected with other components, the head is prone to slip, the installation is not reliable, and there is no push-pull force, resulting in product failure and increased safety hazards.
The lifting ring screw should be made of 20 or 25 steel (GB699). The lifting ring screw must be forged as a whole. The forgings should be normalized and the oxide scale should be removed. The grain size of the finished product should not be lower than grade 5 (YB27-77). There must be over-burning, crack defects.
In order to overcome the above problems, Guangdong Yueluo Hardware Industry Co., Ltd. provides a screw that can be quickly installed and removed. Using the principle of lever, press the handle downward, and the screw can form a backward force through the connecting piece. Press the screw and nut tightly; lift the handle, the screw forms a forward force, and the screw can be removed. Thus, the time and manpower for screwing during installation and disassembly are reduced. The solution adopted by Guangdong Yueluo Hardware Industry Co., Ltd. to solve its technical problems is that the entire screw includes a screw rod, a nut, a connecting piece, a circlip, a positioning pin, a small shaft, a fixed piece, a base, and a handle; the screw is connected by the small shaft at the upper end. At the upper end of the connecting piece, the handle is connected to the lower end of the connecting piece, and the front end of the handle is connected to the base fixing piece through a positioning pin. There are gaps at both ends of the small shaft, and the small shaft is installed through the circlip. The front end of the handle can only be rotated on the positioning pin. Due to the lever principle, when the handle is pressed down, it will drive the screw at the front end of the connecting piece, so that the screw generates a backward force and tightens the screw and the nut. On the contrary, when the handle is pulled up, the screw generates a forward force, so that the screw can be easily removed. The beneficial effect of Guangdong Yueluo Hardware Industry Co., Ltd. is that the quick-opening screw saves the time and labor of repeatedly twisting the nut during installation and disassembly. The installation and removal process is simple.
The above content is uploaded by Yueluo or the Internet. If there is any copyright issue, please contact [email protected].
