What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
hand screw is a screw with a plastic head, and the user fixes the hand screw by turning the plastic head by hand. At present, a hand screw is disclosed in the market publication number CN202203253U, which includes a plastic head and a screw rod, the plastic head and the screw rod are connected together, and the height of the plastic head is higher than that of an ordinary screw, and the height is 12 cm. The screw of the hand screw is fixed in the plastic head by glue. After a period of use, the aging of the glue leads to the loosening of the screw and the plastic head. When the plastic head is stressed, the screw rod comes out of the plastic head, which affects the normal use of the hand screw.
The process of removing iron oxide plate from cold heading steel wire rod is stripping and dephosphorization. There are two methods: mechanical dephosphorization and chemical pickling. Replacing the chemical pickling process of wire rod with mechanical phosphorus removal not only improves productivity, but also reduces environmental pollution. This phosphorus removal process includes bending method (the round wheel with triangular grooves is commonly used to repeatedly bend the wire rod), spray nine method, etc. The phosphorus removal effect is good, but the residual iron and phosphorus cannot be removed (the removal rate of iron oxide scale is 97%) ), especially when the iron oxide scale is very sticky, therefore, mechanical phosphorus removal is affected by iron scale thickness, structure and stress state. Carbon steel wire rods used for low strength fasteners (less than or equal to 6.8) High-strength bolts (greater than or equal to grade 8.8) use wire rods to remove all iron oxide scales after mechanical dephosphorization, and then go through a chemical pickling process for compound dephosphorization. For low carbon steel wire rods, the iron sheets left by mechanical dephosphorization are likely to cause uneven wear of grain draft. When the grain draft hole adheres to the iron sheet when the wire rod rubs against the external temperature, the surface of the wire rod produces longitudinal grain marks. More than 95% are caused by scratches on the surface of the steel wire during the drawing process. Therefore, the mechanical phosphorus removal method is not suitable for high-speed drawing.
A T-bolt. This kind of bolt includes a bolt shank and a bolt head, and the bolt head adopts a special cylindrical bolt head, which can be suitable for installation and cooperation of various sizes. Although the shape of such a bolt head is greatly improved compared to the square bolt head in the prior art, the cylindrical bolt head is particularly inconvenient to install, and special installation tools must be used for installation. If the manual direct installation method is adopted, since the force area of the finger touching the side of the cylinder is small, it will increase the difficulty of the installation work and needs to be improved.
However, although the existing screws can meet the function of connecting and fastening objects, they are all pressed against the object by the head to achieve the purpose of pressing and fixing. However, due to the small size of the head, it is difficult to press the object firmly. , for this reason, only spacers can be added to increase the pressing area. However, in the assembly process, the gasket is prone to slip off, and it needs to be supported by hand, which brings inconvenience to installation and use; at the same time, sometimes the object to be pressed is only on one side of the screw, and the other side of the screw does not need to be pressed. This results in unnecessary waste of materials, and also occupies a certain space, which brings trouble to the installation of other components.
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