What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The positioning pin is a pin designed to accurately position the two adjacent parts of the mold in a mold composed of two or more parts. It can be seen that the positioning pin plays a positioning role, and the mold must be accurately synchronized when it is closed. product, and the positioning pin can make the upper and lower molds play a role in accurate positioning. In the mold design and manufacture of Yueluo, the positioning pin is one of the most common parts. Since it is only used for positioning between parts, few people will pay too much attention to it. In the cold stamping process of Yueluo, the dimensional accuracy of the blanking parts depends on the size of the working part of the punch and the concave die, and the dimensional difference between them constitutes the blanking die gap. Gap is an important process parameter for die design, and its size has a great influence on the quality of the section of the blanking part, the blanking force, and the life of the die. If the gap is too large, punching burrs will appear in punching; if the gap is too small, secondary cracks will occur in the section and extrusion burrs will appear, which will make the quality of the section after punching unsatisfactory, and a reasonable gap will not only help the punching section. The improvement of quality also contributes to the improvement of the lifespan of the 9 bottles.
Process equipment for aircraft production (hereinafter referred to as tooling) is directly used for part forming and component assembly. In order to satisfy the loading and unloading of aircraft parts and components during the use of the tooling, the tooling generally adopts a structural form that is easy to disassemble as a whole. In the field of aircraft process equipment manufacturing, positioning pins are usually used to connect and position the detachable parts of the tooling. At present, this kind of locating pin is divided into two types: direct pull-out locating pin and tie-suspended locating pin.
Referring to Figure 1, one end of the existing insert nut 1' is embedded in the injection molded part 2', and the other end is exposed to the injection molded part 2'. The insert nut 1' has opposite lower and upper end surfaces in the axial direction. The end face of one end of the insert injection molded part 2' is the lower end face. In order to reduce the resistance during hot pressing, the connection between the inner wall surface and the lower end surface of the insert nut 1 ′ is provided with an inclined surface. However, when the embedded nut 1' of this structure is hot-pressed, the hot melted glue will generate a shunt that rises along the slope, and then a convex peak is formed in the screw hole of the embedded nut 1', and the convex peak occupies the screw. The space in the hole prevents the screw 5' from being completely screwed in; at the same time, due to the shunting of the hot solder, the knurling of the inner nut 1' near the upper end face cannot be filled with the solder, which makes the inner nut 1' and the inner nut 1' and The injection part 2' is not firmly embedded. Therefore, the locking strength of the existing insert nut 1 ′ and the screw 5 ′ after being hot-pressed is relatively low.
In order to prevent the waste of materials, those skilled in the art select steel wire as the processing material, and form an annular ring body by drawing the steel wire. Such as the announcement: CN103522009's invention name is a method of processing a retaining ring. The steel wire is used as the processing material, and the processing is carried out by drawing. After the steel wire is drawn and formed, annealing is performed. After the annealing is completed, the forming needs to bundle the steel wire. Since the cross section of the steel wire is rectangular, when it is drawn into the retaining ring base, the cross section changes due to the extrusion of the material, and the inner ring of the retaining ring base will be higher than the outer ring (forming a slope). The deformation is large. At this time, the punching of the opening of the retaining ring base body will produce a slump or cause greater material deformation; therefore, the retaining ring base body needs to be bundled. The bundling process is to prevent the material from being heated more during the quenching process. At the same time, it also has a certain adjustment effect during the quenching process, which makes the inclined surface smaller; but after the quenching is completed, the hardness of the retaining ring base increases, and the punching process for the upper opening will become more complicated.
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