What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Advanced bolts are the foundation of high-end machinery manufacturing, and their role can be called four ounces. On the surface, the output value of bolts only accounts for a few percent of the machinery industry. In essence, the added value it brings to key components and equipment is much higher. Over the years, after the continuous double-digit growth of Chinese bolts, the bolt industry experienced negative growth in 2012, down about 1.5% year-on-year, mainly due to insufficient market demand, especially after the bolts suffered from international anti-dumping, export sales declined. situation. [1] The competition in the bolt market is fierce, and it is moving towards brand management. In the past 10 years, the development speed of China Bolt has attracted the attention of the world, which surprised the developed countries, but also made them discover a new type of big market, and multinational companies filed in. When domestic bolt companies suddenly feel that it is so difficult to survive in the market, powerful competitors have blossomed everywhere. In today's Chinese bolt market, some small and medium-sized bolt enterprises manufacture a large number of common standard parts, which does not really bring core competitiveness to the enterprise, but is subject to changes in raw materials, labor costs and other conditions. From 4.8 to 6.8 low-strength bolts, or 8.8 to 12.9 high-strength bolts, the production technology level of Chinese bolts will be basically close to the world's advanced level, mainly ordinary standard parts and low- and medium-grade special and special-shaped bolts, with large quantities Inexpensive. It can be concluded that low-grade products flood the dominant market, a small part of high-grade, high-precision, high-strength bolts still need to be imported, and the difference between the unit price of products imported and the bid price is about 6 times or more. It can be seen that China's bolt industry is still a developing industry, big but not strong, fat but not strong, and the gap with the United States, Japan, South Korea and Taiwan, my country, and lack of technical services to solve mechanical tightening. A solid solution to realize the digitalization of products, design, manufacturing and management, and the greening of products and manufacturing processes. It is understood that the development of Chinese bolts is under increasing pressure from resources and the environment. An important way to alleviate resource constraints is to develop green manufacturing. The development of bolts will continue to be actively promoted in the direction of brand management for a period of time in the future, and promote the development of bolt projects in all directions. [1] In terms of products, mid-to-high-end products will accelerate the localization of quality research and development. The whole process from design, manufacturing, packaging, transportation, use to end-of-life treatment must consider the least waste, the lowest emissions, and the high resource utilization rate. And the environmental impact is minimized, so that the corporate benefits and social benefits are coordinated and optimized. [1] In terms of circulation, explore various value-added service models to bring value and benefits to customers. From providing a single set of bolts to providing mechanical fastening solutions, customized services, remote monitoring, etc., the proportion of services in the sales revenue of bolt manufacturers will gradually increase. [1] Corporate restructuring is a trend, and strategic alliances seek development. At present, the low industrial concentration of China's bolt enterprises has seriously restricted the improvement of China's bolt competitiveness. The market opening over the years has not brought the core technology. In view of the above situation, the reorganization and strategic alliance between enterprises is a major trend. China's bolt industry must conform to this trend and trend, strengthen strategic cooperation between enterprises, and improve the overall competitiveness of China's bolts. China's growth in the field of bolt core technology lacks breakthroughs. At the same time, the living space of low-end products is getting smaller and smaller, and foreign capital through localized enterprises also has considerable cost advantages, coupled with the advantages of technology brands, and began to enter the market space of the original independent brands.
2. Wall panel nails 1. Hardness of the heart: Standard: HRC24-45. 2. Surface hardness: Standard: HV600-800. 3. Carburized layer: 4#-6# 0.05-0.18mm, 8#-12#0.10-0.23, 14# 0.13-0.28. 4. Bending degree: the requirement is 150-450 5. Salt spray test: generally MIN 48h. 6. Torque: Specification 6#7#8#10# Torque 21283558. 3. Drilling screw 1. Hardness of the heart: Standard: HRC32-40 The actual measurement of the company's products is HRC31.7-39.0. 2. Surface hardness: Standard: HV600-700 The actual measurement of the company's products is about HV620. 3. Hard penetration layer: 4#-6#: 0.05-0.18mm 8#-12#: 0.10-0.23mm 14#: 0.15-0.28mm 4. Torque: specification, drill tail, screw, TYPE BSDTYPE CSDINCH-LBKG- CMINCH-LBKG-CM4# (2.9) 141614166# (3.5) 242824288# (4.2) 4248485510# (4.8) 6170657512# (5.5) 9210610011514# (6.3) 150173156180.
1. The twisted screw should be considered according to the actual inner diameter of the barrel, and the outer diameter deviation of the new screw should be given according to the normal clearance with the barrel. 2. After the thread surface with the reduced diameter of the worn screw is treated, the wear-resistant tungsten carbide alloy is thermally sprayed, and then ground to size. 3. Surfacing wear-resistant tungsten carbide alloy on the thread part of the worn screw. According to the degree of screw wear, surfacing welding is 1~2mm thick, and then the screw is ground and processed to size. This wear-resistant tungsten carbide alloy is composed of materials such as C, Cr, Vi, Co, W and B, which increases the wear resistance and corrosion resistance of the screw. 4. The bottom diameter of the screw is repaired by electroplating hard chromium. Chromium is also a wear-resistant and corrosion-resistant metal, but the hard chromium layer is easier to fall off.
1. Precautions for the quality of high-strength bolts or screws and flat washers assemblies. The surface of the Phillips hexagon combination screw should be checked for burrs or scratches. There is no oil stains, or rust. To test the material of the combination screw, the strength of the grade used in different high strengths should be consistent with it. Second, the combination bolt and nut should be used together with the same grade as the nut, and the same grade should be used together. Third, when installing and using combined bolts, it should be in reasonable weather conditions and should not be operated in the rain. Fourth, when installing, it is forbidden to use excessive force and excessive force. Lead to sliding teeth, or locking phenomenon.
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