What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Surface treatment process of screws 1. Types of surface treatment: Surface treatment is the process of forming a covering layer on the surface of the workpiece by a certain method. The purpose is to give the surface of the product a beautiful and anti-corrosion effect. The following methods are as follows: 1. Electroplating: Immerse the part to be electroplated in an aqueous solution containing the metal compound to be deposited, and pass the current through the plating solution to precipitate and deposit the electroplated metal on the part. Generally, electroplating includes galvanized, copper, nickel, chromium, copper-nickel alloy, etc., and sometimes blackening (blue), phosphating, etc. are also included. 2. Hot-dip galvanizing: It is done by immersing the carbon steel parts in a zinc-melting bath with a temperature of about 510°C. The result is that the iron-zinc alloy on the surface of the steel gradually becomes passive zinc on the outer surface of the product. Hot dip aluminizing is a similar process. 3. Mechanical plating: The surface of the product is impacted by the particles of the plated metal, and the coating is cold welded to the surface of the product.
Most of the existing belts control the length of the belt by fixing the other end of the belt by the buckle, and the period that is often buckled by the buckle will be deformed and damaged after long-term use, and the user may change the position from standing to sitting or after meals. The circumference of the belt can be adjusted, and micro-adjustment is not necessarily possible when adjusting the tightness of the pin buckle type or buckle plate type belt buckle. In order to solve this problem, it is necessary to design a belt that is relatively suitable for the waist of a person.
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.
At present, for roller or needle roller bearings without cages, ribs, and low-speed operation, the structure mainly includes inner and outer rings and rollers or needle rollers in the raceway between the inner and outer rings, and additional The retaining rings on both sides of the roller or needle roller, among which the retaining rings added on both sides of the roller or needle roller are annular steel sheets punched from metal sheet, and their function in the bearing is only Correctly guide the rollers or needle rollers to run normally in the raceway between the inner and outer rings to prevent the rollers or needle rollers from deviating and slipping out of the raceway. The defect of the retaining ring of this structure is that first, because the rigid retaining ring and the inner ring are completely separated, there is a gap between the retaining ring and the installation shaft during installation. When the bearing is working, The retaining ring is driven by the outer ring and the rollers or needle rollers to rotate around the installation shaft. Due to the inconsistency of the structure, the retaining ring is easy to fall off during the rotation process, the safety of use is poor, and the rollers or needle rollers will appear toward the raceway. The situation of one side offset, which causes the bearing load center to offset, affects the reliability of the bearing operation, and ultimately affects the service life of the bearing; There is a gap between the raceways of the needle, so the tidbits, dust, etc. generated during the working process will continue to enter the raceway between the inner and outer rings. It is stuck; in addition, due to the gap between the steel retaining ring and the raceway, the grease stored in the raceway will be continuously lost, which will cause the bearing to heat up due to frequent lack of grease, or even burn out, which also affects the to the service life of the bearing.
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