What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
China is the world's largest producer of carbon steel fasteners such as screws, nuts and bolts, and the EU is a major market for these products. In January 2009, the EU decided to impose anti-dumping duties of 26.5% to 85% on Chinese carbon steel fastener products. On July 31 of the same year, China resorted to the relevant EU legislation and anti-dumping measures to the WTO dispute settlement mechanism. The case became China's first lawsuit against the EU at the WTO. On July 15, 2011, the WTO Appellate Body issued a report and finally ruled that China won the case in the trade dispute with the European Union on fasteners. The head of the Department of Treaty and Law of the Ministry of Commerce of China welcomed the ruling on the 16th, and said that China's victory in the case is of great significance, which will help improve the competitive environment for Chinese companies in the international market including the European Union, and will also strengthen the WTO members' interest in the case. Confidence in WTO rules and the multilateral trading system. This is not only a victory for China's industry, but also a victory for WTO rules, the official said. The WTO Appellate Body found in its ruling report issued on the 15th that Article 9(5) of the EU's Basic Anti-dumping Regulations on individual tax rates violated WTO rules; at the same time, the Appellate Body overturned some of the panel's rulings and supported China's position , ruled that the EU's anti-dumping measures against Chinese screws, nuts, bolts and other carbon steel fasteners also violated WTO rules in terms of domestic industry identification, normal value and fair comparison of export prices. The head of the Treaty and Law Department of the Ministry of Commerce of China said that the EU is one of the WTO members that has initiated the most anti-dumping investigations against Chinese products in the world. unfair treatment. He said that China hopes that the EU will cancel the legislation and discriminatory anti-dumping measures that are inconsistent with WTO rules as soon as possible, treat Chinese export enterprises fairly, and effectively safeguard free trade and fair competition.
In the household and industry, when installing furniture, home appliances, electrical appliances, equipment and other objects, the objects are uneven or uneven due to the uneven bottom of the object, or because the placement surface or installation surface is uneven, or because the two surfaces are different and do not fit together. stable, produce vibration, shaking or sliding, affecting the use effect and service life. Sometimes two items need to be placed next to each other, but their surfaces cannot be in direct contact, otherwise the surfaces will be damaged. For these two cases, the common solution is to install gaskets. There are two types of gaskets: wedge and flat. The wedge-shaped gasket adjusts the actual thickness by adjusting the length of the insertion gap, but the contact surface and load-bearing surface of this method are small, and due to its wedge-shaped structure, the gasket may withdraw after being stressed for a long time. Flat gaskets are generally made from local materials, using waste paper, plastic, rubber, metal and other materials to form the required thickness by folding or stacking. Such gaskets are often not quickly assembled to the exact desired thickness, are not aesthetically pleasing, and are not reusable. The purpose of Guangdong Yueluo Hardware Industry Co., Ltd. is to provide a product that can keep furniture, home appliances, equipment, electrical appliances and other objects horizontal, vertical or stable, prevent them from vibrating, shaking or sliding, and can provide appropriate thickness and beautiful appearance. gasket. The purpose of Yueluo is to realize a gasket that can be combined at will. The sheet 1 is provided with small holes 3 , and the connecting device 2 connects a plurality of sheets 1 together through the small holes 3 . The connecting device 2 is a rivet or a screw. The material of the sheet 1 can be plastic, metal, paper card or rubber. The gaskets provided by Yueluo can be combined at will. Multiple sheets are connected together by rivets or screws. By opening or closing the sheets, or dismantling the screws, the sheets are reassembled to obtain a combination of gaskets with different thicknesses and elasticity. The space between the installation object and the installation surface to keep the object horizontal, vertical or stable and prevent it from vibrating, shaking or sliding.
1) Scope This standard specifies the lock nut (referred to as nut), the size of the locking device, technical requirements, acceptance rules and measurement methods. This standard applies to the design, production, inspection and user acceptance of nuts and locking devices for tapered bushings. 2) Terminology The terms used in this standard conform to the provisions of GB/T 6930. This standard specifies the marking system, index, test method and marking of the mechanical and working performance of the effective torque section steel hexagonal lock nut. This standard is applicable to coarse thread 6H class nuts made of carbon steel or alloy steel, the width across the sides conforming to the provisions of GB 3104, the nominal height is ≥ 0.8D, and the guaranteed load and effective torque need to be specified, and the thread diameter is 3 ~ 39mm. Except for the effective torque part, the thread size and tolerance are specified in GB 193, GB 196 and GB 197. The working temperature range of the nut should be in accordance with: All-metal nut without electroplating treatment: -50℃～+300℃. All-metal nuts with electroplating treatment: -50℃～+230℃; nuts embedded with non-metallic elements: -50℃～+120℃. This standard does not apply to nuts with special performance requirements (such as weldability and corrosion resistance). For stainless steel and non-ferrous metals with fine pitch lock nuts or thin nuts made of carbon steel or alloy steel, the performance indicators and test methods of effective torque specified in this standard may be adopted by mutual agreement.
The technical process of nickel-phosphorus plating for high-strength bolts consists of three parts: The first part is the pre-treatment process, including the precision and appearance inspection of high-strength bolts before plating, manual degreasing, immersion degreasing, pickling, electro-activation and flash nickel plating and other processes; the second part is the electroless nickel plating treatment process; the third part is the post-treatment process, including the processes of hydrogen-displacing heat treatment, polishing and finished product inspection. As follows: Bolt chemical composition inspection → bolt pre-plating accuracy, visual inspection → manual degreasing → visual inspection → immersion degreasing → hot water washing → cold water washing → pickling → cold water washing → electric activation → cold water washing → flash nickel plating → cold water washing → Deionized water washing → Electroless nickel plating → Deionized water washing → Cold water washing → Hydrogen removal → Polishing → Finished product inspection.
The above content is uploaded by Yueluo or the Internet. If there is any copyright issue, please contact [email protected].
