What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The pretreatment process is a key process that determines the quality of nickel-phosphorus plating on high-strength bolts. The purpose of this process is to remove the passivation layer on the surface of the bolt and prevent the regeneration of the passivation film. The execution of this process directly determines the degree of bonding between the substrate and the coating. Most of the quality accidents in production are caused by poor pretreatment of bolts. Before plating, the oil, rust and oxide scale attached to the surface of the bolt must be carefully removed; the difference with electroplating is that it should be inspected more carefully, and plating is absolutely not allowed on unclean bolts. ① Inspection of bolts: Visual inspection of the surface quality of bolts requires that any burrs left by processing must be removed, and sharp edges and corners must be rounded. ② Manual degreasing; ensure that the surface of the substrate is free of oil stains. ③ Soak and remove oil; boil the bolts in alkaline water to remove the surface oil. ④ Pickling: In order to prevent the alkaline degreasing solution from contaminating the flash nickel plating tank, electro-activation treatment is carried out with pickling solution before flash nickel plating. ⑤ Electro-activation; electro-activation treatment with acid solution. ⑥ Flash nickel plating; flash nickel plating should be used for low alloy steel to increase the bonding strength between the coating and the substrate.
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.
Pins are widely used. In the connection of the rotating mechanism of two moving components, such as the crank mechanism, the turning mechanism, the connection between the hydraulic cylinder and the moving parts, the pins are used. kind. In order to ensure the normal use of the running equipment and prevent the cylindrical pin from slipping out and falling off during use, some anti-falling methods are usually used at the head of the pin, such as 1. Drill holes and insert cotter pins to prevent the pins from slipping out; 2. The external thread is tightened with a nut to prevent the pin from slipping out; 3. The slot is clamped with a circlip to prevent it from slipping out, etc. These measures make the cylindrical pin very practical in the case of infrequent disassembly and assembly, but in the actual use of the field, in order to prevent the collision of some equipment during each troubleshooting or maintenance, the pin needs to be pulled out and turned up, etc. After the failure or maintenance is completed, put down and then insert the pin to restore, this process will bring trouble to the actual operator. For example, special tools must be brought with you every time you disassemble and assemble the pin, and the split pin or the circlip is easily damaged after repeated disassembly and assembly. , In order to save trouble, the operator sometimes uses iron wire to thread or fasten it instead, and even does not remove the pin for the sake of speed and convenience, which is easy to cause damage to the equipment when dealing with faults.
When using ordinary hexagon head bolts or ordinary T-bolts with the oval groove structure, the bolts need to be inserted from the back of the groove. When the bolts cannot be inserted from the back of the groove due to the structural limitations of the steel base or the platform itself, it is often necessary to open the installation surface. Large diameter hand holes allow for easy mounting of bolts, which weakens the inherent strength and rigidity of a steel base or platform.
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