What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
ANSI B1.1 Thread Pitch Comparison Table Nominal Diameter (inch〖mm〗) Coarse Thread Pitch (UNC) Fine Thread Pitch (UNF) Ultra Fine Thread Pitch (UNEF) Drilling Diameter (Coarse Thread) Drilling Diameter (Fine Thread) #0 0.060 〖1.524〗 80 1.2 # 1 0.073 〖1.5 1.5 # 2 0.086 〖2.8 # 3 0.099 〖2.515〗 48 56 2.0 2.1 # 4 0.112 〖2.4 # 5 0.125 〖 3.175〗 40 44 2.5 2.6 # 6 0.138 〖3.50〗 32 40 2.7 2.9 # 8 0.164 〖4.166〗 32 36 3.4 3.5 # 10 0.190 〖4.0 # 12 0.216 〖5.486〗 24 28 32 4.5 4.6 1/4 6.35 20 28 32 5.1 5.4 5/16 10.7 11.5 9/16 〖14.288〗 12 18 24 12.3 13.1 5/8 〖15.875〗 11 18 24 13.5 14.7 3/4 〖19.05〗 10 16 20 16.7 17.5 7/8 〖22.125 2.4 9 14 〗 8 12 20 22.2 23.4 The pitch is expressed by the number of teeth per inch, such as: 11 teeth per inch, then the pitch=25.4/11=2.309mm. The unit of pitch in the table is the number of threads per inch. The hole diameter is the recommended hole size for tapping, in millimeters.
In the production process of Yueluo, according to the different gap guarantee schemes adopted in the mold design, different gap assembly adjustment methods are adopted accordingly. At present, the gasket method, light transmission method, measurement method, copper plating (zinc) method are often used Method, coating method, process allowance, locator positioning and other assembly adjustment methods. Generally speaking, for the working parts processed separately by the punch and the concave die, since the reasonable gap of the die has been formed theoretically, the assembly principle is to fix the working part that is not easy to adjust, and adjust the working part of the other working part. To change the position between the punch and the die to ensure a uniform gap, at this time, only the screws are pre-tightened, and the positioning pins are not fixed. Yueluo, however, many years of practical experience have made those skilled in the art notice that if they can pay attention to the positioning pins and use the positioning pins in a targeted manner in the mold design or manufacturing process, they can often produce miraculous results with half the effort. Therefore, it is very important to design a positioning pin for a specific mold, which is of great practical significance.
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 the quality also contributes to the improvement of the lifespan of the 7-pack.
Generally, the most commonly used material on the market is iron. The iron one is known as carbon steel. It is punched out or turned. After being manufactured, it is in its natural color. In order to prevent rusting, it is necessary to Electroplated. The stainless steel rivet nuts do not need electroplating. In the case of iron, the color of electroplating is generally determined by the customer, and the color of the electroplating depends on what color the customer needs. There are also some requirements for salt spray time. Some electroplating colors have a higher salt spray time, and some electroplating, less rust in a few hours. Another point is to see whether the customer needs to export the product. Generally, the export needs to be environmentally friendly, and some domestic ones also need it, but most of them are not needed.
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