Service HotlineWhen using screws, if you can understand the mechanical properties of screws first, then you can use screws better. Different types of screws have different mechanical properties, and the different mechanical properties lead to different occasions when screws are used. 1. Self-tapping screws: mechanical performance requirements 1. Heart hardness: standard value HRC28-38. When testing, take the section 1-2 times the diameter of the name from the tail. If the length of the name is too short, it can be embedded first, and then the hardness is measured. 2. Surface hardness: standard MIN HV450. 3. Carburized layer: standard 4#-6#: 0.05-0.18mm, 8#-12#: 0.10-0.23 mm, 14#: 0.13-0.28 mm. The main purpose of carburizing is to enhance the surface hardness and ensure the strength of the teeth. If the decarburization is too deep and the carburization is insufficient, the strength of the teeth will not meet the requirements, that is, the teeth will be damaged during the screw-in test. 4. Torque: standard specification 4#5#6#7#8#10#12#14#A tooth 14212835455696145AB tooth 142128354565102165. 5. Screw-in test: screw the self-tapping screw into a steel plate with a reserved test hole. The self-tapping screw should form a matching thread in the test plate, and the thread of the screw itself will not be deformed or damaged until the end. Tapered threads pass completely through the test plate. The screw-in test is only applicable to AB, B, BP and other types of self-tapping screws. It is stipulated in IFI that the test plate shall be prepared from semi-hard low-carbon cold-rolled steel, and the hardness of the steel plate is 70–85HRB in Rockwell. The standard specification of the steel plate, that is, the thickness, is shown in the table below. The test hole should be punched or drilled, and the tolerance is the specified nominal diameter (see the table below) ± 0.025mm. Specifications 6#7#8#10#12#1/4 Test plate thickness (mm) 1.85-1.953.12-3.234.68-4.84 Aperture (mm) ±0.0252.953.263.454.044.765.50.
The quality of the combination screw should start with the screw wire of the combination screw manufacturer. The wire of the screw is the first hurdle to determine the quality of the combination screw. Even if the wire is not good, even if the production equipment is advanced and the staff is skilled, it is impossible to produce high-quality combination screws. In the second look at the quality of the combination screw products, from the overall aesthetics of the combination screw. A combined screw is formed, the size of the screw head, the superior appearance of the flat washer, whether the screw thread can pass the stop gauge, etc. These are all things that need to be detected. A good combination screw, its overall standard can meet the national standard requirements, or customer requirements. Finally, the quality of the combination screw product is seen from the color of the plating. Of course, the iron combination screw needs to be plated, but the stainless steel combination screw does not need it. Some of them are passivation at most, in order to increase the salt spray resistance of stainless steel combination screws. In the electroplating color of the combination screw, some of them are not well controlled, which will produce a great color difference. That doesn't look good.
Further, the pressure riveting portion and the pressure-bearing portion are both columnar structures, the outer diameter of the pressure-bearing portion is larger than the outer diameter of the pressure riveting portion, the pressure riveting portion is a stepped structure, and the diameter of the lower end of the pressure riveting portion is smaller than that of the pressure riveting portion. The diameter of the upper end of the rivet part.
screw can be equipped with only one spring washer or only one flat washer, or it can also only be equipped with a two-piece combination of flower teeth. The national standard number of the combination screw is represented by GB9074. The commonly used cross recessed small pan head three combination screw national standard is GB9074.8.
The four corners of the bolt head of the traditional T-slot connection bolt are all rounded corners, which will make the contact area between the bolt and the T-slot too small and reduce the connection fastness, especially when used for connection. When aluminum or copper profiles are used, due to the low hardness of the material, it is more likely to cause deformation of the T-shaped groove and affect the connection effect. Furthermore, since the traditional T-bolt has no direction indicator, it is difficult for the installer to identify the installation state during installation.
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