What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The elastic cylindrical pin, also known as the spring pin, is a headless hollow cylindrical body, which is slotted in the axial direction and chamfered at both ends. It is used for positioning, connection and fixation between parts. The outer diameter of the spring pin is usually slightly larger than the mounting hole. The deformation force generated by the elastic cylindrical pin to be restored to its original state by extrusion ensures the clamping effect of the elastic cylindrical pin. But just because of its clamping effect, it will play a big obstacle to the disassembly of the elastic cylindrical pin. When in use, the open end is extended out of the through hole on the pin shaft, and the open end is flared and separated to prevent the elastic cylindrical pin from sliding off the pin shaft to realize the function of preventing backlash. At present, the disassembly method of the elastic cylindrical pin usually uses a punching machine to remove the cylindrical pin, which easily destroys the equipment installed on the cylindrical pin, and the disassembled elastic cylindrical pin cannot be used again due to damage. One method is to insert the mounting pin with the clearance fit of the mandrel, punch the pin behind the mandrel to clamp the bottom of the cylindrical pin, and then pull out the cylindrical pin, which can only be used when the elastic mounting pin is installed in the through hole, and because it is necessary Applying force to the mandrel increases the difficulty of disassembly and increases the work intensity of the installer. Three methods are done by the installer using two needle nose pliers. Specifically, first use needle-nose pliers to clamp the ends of both sides of the elastic cylindrical pin, and then apply an inward force to the needle-nose pliers, so that both sides of the elastic cylindrical pin rotate in the same direction until the opening becomes smaller, and then Pull it out to remove it successfully. The defects of these existing methods are obvious. The shape of the disassembled elastic cylindrical pin is either unusable or the deformation of the cylindrical pin after disassembly is not uniform, which seriously affects the performance of the elastic cylindrical pin, resulting in waste and increased cost; The method is purely manual work, and sometimes it takes several repetitions to remove the elastic cylindrical pin. Due to the different installation positions of the elastic cylindrical pin, it sometimes increases the difficulty of disassembly, and it is difficult to remove the needle-nose pliers effectively. The pliers are difficult to construct, and the elastic cylindrical pins are easily damaged. If there are too many elastic cylindrical pins to be disassembled, the existing methods are often difficult to meet the needs, which not only consumes a lot of time and physical strength of the installer, but also makes it difficult to ensure the quality.
The advantage of wood screws is that the consolidation ability is stronger than that of nails, and they can be removed and replaced, which is more convenient to use without damaging the wood surface. This is a kind of nail specially designed for wood, and after entering the wood, it will be embedded in it very firmly. If the wood is not damaged, it is impossible to pull it out, and even if it is pulled out forcibly, it will bring out the nearby wood. Another point to note is that the wood screws must be screwed in with a screwdriver. Never knock them in with a hammer, as it will damage the surrounding wood. A screwdriver is a tool for loading and unloading wood screws. The shape matches the groove shape of the wood screw head, and there are two types: one-word and cross-shaped. In addition, there is a special screwdriver installed on the bow drill, which is suitable for loading and unloading large wood screws. Convenient and labor-saving. [2]
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.
Yueluo Company adopts the following technical solutions: fasteners for preventing nuts from falling off, including bolts and nuts, the nuts are provided with screw holes, the screw holes are provided with internal threads, the bolts are provided with M grooves along its axial direction, M ≥1; There is an arc-shaped notch on the screw hole of the nut, and there are N V-shaped tooth grooves along the axial direction of the nut in the arc-shaped notch, N≥2; a locking strip is placed in the groove, and the locking The bar includes a locking bar body and a V-shaped locking tooth, the width of the locking bar body is the same as the width of the groove, the V-shaped locking tooth is located on one side of the locking bar body, and the V-shaped locking tooth is engaged with the V-shaped locking tooth.
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