What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Bolts or screws and flat washers assemblies GB/T 9074.1-2002 Cross recessed head screws and external serrated lock washers assemblies GB 9074.2-88 Cross recessed pan head screws and spring washers assemblies GB 9074.3-88 Cross recessed pan head screws, springs Washer and flat washer assembly GB 9074.4-88 Cross recessed small pan head screw and flat washer assembly GB 9074.5-88 Cross recessed small pan head screw and large washer assembly GB 9074.6-88 [1] Cross recessed small pan head screw and spring washer Assembly GB 9074.7-88 Cross recessed pan head screw, spring washer and flat washer assembly GB 9074.8-88 Cross recessed countersunk head screw and conical lock washer assembly GB 9074.9-88 Cross recessed countersunk head screw and conical lock Tight washer assembly GB 9074.10-88 Cross groove hexagon head bolt and flat washer assembly GB 9074.11-88 Cross groove hexagon head bolt and spring washer assembly GB 9074.12-88 Cross groove hexagon head bolt, spring washer and flat Washer assembly GB9074.13-88 Hexagon head bolt and spring washer assembly GB 9074.15-88 Hexagon head bolt and external serrated lock washer assembly GB 9074.16-88 Hexagon head bolt, spring washer and flat washer assembly GB 9074.17-88 From Tapping screw and flat washer assembly GB /T 9074.18-2002 Cross recessed hexagon head self-tapping screw and flat washer assembly GB 9074.20-88 Cross recessed hexagonal head self-tapping screw and large washer assembly GB 9074.21-88 For assembly Spring Washers GB 9074.26-88 External Serrated Lock Washers for Assemblies GB 9074.27-88 Conical Lock Washers for Assemblies GB 9074.28-88.
The product structure in the known technology includes a T-shaped bolt with a longitudinal section, and a polygonal nut matched with the bolt. The bolt is divided into two parts: the screw and the screw head. The screw head is placed at one end of the screw to form an integral part. The radial length of the tightening surface of the screw head is greater than the radial length of the screw, and its axial length is less than the axial length of the screw; The solid surface is a polygon, and now a hexagon is commonly used. The periphery of the base of the nut and the screw head has a number of elastic surfaces corresponding to the polygon; the periphery of the axial screw is provided with an external thread matching the internal thread of the nut. In actual use, the fastener of this structure can be tightened by using a conventional screw, such as a wrench. Therefore, its anti-theft performance is poor and it is not suitable for occasions with special requirements.
Screw: A type of fastener consisting of a screw head and a screw rod (a cylinder with an external thread), which needs to be used in conjunction with a nut to fasten and connect two parts with through holes. and widely used in people's lives. In real life, due to the vibration of the machine, the workpiece is loose at the connection between the screw and the nut, and the nut needs to be tightened frequently, which is time-consuming and laborious, delays time, and reduces the production efficiency, so how to reduce the production process. Frequent tightening of screws has become an unsolved problem for people. Therefore, there is an urgent need to provide a slotted screw.
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.
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