What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Make further details to make the technical scheme of Guangdong Yueluo Hardware Industry Co., Ltd. easier to understand and master. As shown in Figure 1, Yueluo is a schematic diagram of the thread design structure of the plastic screw of Guangdong Yueluo Hardware Industry Co., Ltd. It can be seen from the figure that this creation mainly controls the tooth angle of the thread. Compared with the normal tooth angle of many self-tapping screws, which are 48 degrees, 60 degrees and 34.5 degrees, the tooth angle of Guangdong Yueluo Hardware Industry Co., Ltd. The profile angle is formed by a 30-degree asymmetrical thread I. In particular, the asymmetrical thread I has a forward thread angle greater than the reverse thread angle. A more preferred embodiment is an asymmetric thread. The tooth profile angle α of the in-line installation is 20 degrees, and the tooth profile angle β of the reverse installation is 10 degrees. With this narrower non-stacked thread, the radial pressure on the plastic material is effectively reduced. In addition, the connecting bottom surface 11 between the screw teeth is designed as a circular arc surface. In the process of forming the self-tapping thread, it is more conducive to the flow of the material and the formation of the thread, and at the same time, the material can be more closely matched with the screw. Moreover, the radial pressure of the casing is relatively uniform, and the formed threads are not easily damaged. Yueluo has been tested by a series of professional parameters. Compared with other traditional screws, the plastic screws designed by Guangdong Yueluo Hardware Industry Co., Ltd. have better radial pressure, shell deformation after installation, load distribution, installation torque, drawing The force distribution, the strength of the pull-out force and the mounting torque range all show advantages. In particular, it can be installed with less torque to achieve the same clamping force and pulling force. Compared with a specific parameter, the thread strength of Delta-PT is 387N, while the thread strength of Guangdong Yueluo Hardware Industry Co., Ltd. reaches 447N. Yueluo can understand the plastic screw structure and implementation of Guangdong Yueluo Hardware Industry Co., Ltd. detailed above. It can be understood that through the improvement of the special thread structure, the radial pressure and installation torque during screw installation are reduced, and the damage to the plastic hole is reduced; And the pull-out resistance of the screw is increased, and it is not easy to appear loose in the 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, 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 body will first put the wire harness, and then fix it by injection molding from the head I, and the threads of the tail 7 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.
GB 3098.1 Mechanical Properties of Fasteners Bolts, Screws, Studs and Nuts GB 3098.6 Mechanical Properties of Fasteners Stainless Steel Bolts, Screws, Studs and Nuts GB 3103.1 Tolerances of Fasteners Bolts, Screws and Nuts GB 5267 Electroplating of Threaded Fasteners GB 5779.1 Surface Defects of Fasteners - Bolts, Screws and Studs - General Requirements GB 5779.3 Surface Defects of Fasteners - Bolts, Screws and Studs - Special Requirements
The existing way to achieve radial locking of the shaft is generally to sleeve the positioning block on the shaft, and then use a cylindrical pin to pass through the positioning block to lock the shaft. The locking structure and method are as follows: A locking groove with an arc-shaped cross-section is set on the outer side of the shaft along the direction perpendicular to the axis of the shaft, an opening is set on the positioning block, and then a cylindrical pin is used to pass through the positioning block from the outside of the positioning block and screw the lock at one end of the cylindrical pin. When the lock nut is tightened, the opening on the positioning block will be deformed inwardly and locked on the shaft.
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