What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Comparing the physical properties of stainless steel and carbon steel, the density of carbon steel is slightly higher than that of ferritic and martensitic stainless steel, but slightly lower than that of austenitic stainless steel; the resistivity is based on carbon steel, ferritic, martensitic and The order of austenitic stainless steel is increasing; the order of linear expansion coefficient is similar, austenitic stainless steel is the highest and carbon steel is the smallest; carbon steel, ferritic and martensitic stainless steel are magnetic, austenitic stainless steel is non-magnetic, But its cold work hardening will generate magnetism when it is transformed into intensite, and heat treatment method can be used to eliminate this martensitic structure and restore its non-magnetic properties. Compared with carbon steel, austenitic stainless steel has the following characteristics: 1) High electronegative rate, which is about 5 times that of carbon steel. 2) The large coefficient of linear expansion is 40% larger than that of carbon steel, and with the increase of temperature, the value of the coefficient of linear expansion of stainless steel screws increases accordingly. 3) Low thermal conductivity, about 1/3 of carbon steel.
T-bolts for channel steel usually include a head and a shank. The shank is provided with threads. Traditional T-bolts for channel steel are used for channel steel, and both channel steel and bolts are made of steel. , the two are prone to thermal expansion and contraction due to changes in the external ambient temperature, and are prone to loosening, resulting in unstable connections.
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 444N. 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.
In the current plastic matrix, it is common to use self-tapping screws or add copper inserts during injection molding. The former has poor strength, and the threaded hole is easy to crack; the processing cost is high, the injection molding efficiency is low, the labor cost and manufacturing cost are increased, and the insert is easy to slip and crack on the plastic, and the thread strength of the copper insert is not as high as that of the iron nut.
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