What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The advantages of Guangdong Yueluo Hardware Industry Co., Ltd. are that the rivet nut is fixed on thin-walled or thin-plate objects without welding, easy operation, high production efficiency, easy to manufacture, low cost, single-sided riveting, firm connection, no pollution, no noise, Has significant economic benefits.
Use performance self-tapping screws for self-tapping screws with a diameter of 0.8mm to 12mm. For this type of screw, it generally has a high hardness. Self-tapping screws must be screwed into the test, that is, screw the screw into a test plate to check whether the hardness of the screw meets the standard. The shape of the drill tail, the hardness of this kind of screw is very strong. Compared with ordinary screws, it not only has better maintenance ability, but also has a very strong effect in connecting objects. For screws with this performance, it is generally not necessary. Auxiliary processing can directly drill a hole on the object and lock it into the object, which is not only very convenient to use, but also greatly improves work efficiency. This kind of drill screw can be said to be the first choice of the staff in various fields.
Fig. 1, Fig. 2, and Fig. 3 show that the rivet nut is cut into the required blank from a chemically treated low carbon steel disc, and the blank is placed in the die, and the upper and lower punches are used for shaping to obtain a shaped blank. , and then put the shaped blank in the die, use the punch punch to cold-head out the required brim blank (1) and the deformed skirt (2), and then use the punch punch in the die to continue Cold heading out the brim blank (1) and the deformed skirt (2). Then put the semi-finished material into the concave die and use the punch of the punch to continue to squeeze the threaded hole (3) of the nut tapping skirt, and then put the semi-finished blank into the concave die and use the upper punch and the lower sleeve to drop it. material. There are fish teeth (6) below the brim; the outer side of the lower end of the threaded hole is provided with a chamfer (5); the cross-section of the thread of the inner wall of the threaded hole is an isosceles trapezoid, and the upper bottom of the trapezoid is a concave arc (4), In this way, the riveted object is firmly connected to the rivet nut.
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.
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