What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Heat treatment technology has a crucial impact on high-strength fasteners, especially its intrinsic quality. Therefore, in order to produce high-quality high-strength fasteners, advanced heat treatment technology and equipment must be available. 1. Status of heat treatment of high-strength fasteners High-strength fasteners have 4 performance levels, namely 8.8, 9.8, 10.9, and 12.9. These four grades of high-strength fasteners must be quenched and tempered. The purpose of heat treatment and tempering is to improve the comprehensive mechanical properties of fasteners to meet the specified tensile strength value and yield ratio of the product. Therefore, the quenching and tempering process has strict requirements on raw materials, furnace temperature control, furnace atmosphere control, quenching medium, heat treatment quality inspection and control, etc.
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.
However, for some thin-walled parts (such as metal material parts with a thickness of less than 1mm), the combination of cylindrical pins and edge-cutting positioning pins is used as the positioning method on the workstation equipment. In the process of automatic grasping by mechanical grippers, there are many The disadvantage is that if the positioning accuracy is to be met, it is inconvenient for the parts to be placed in the station utensils, and it is also inconvenient for the mechanical gripper to grasp the parts, and it is easy to cause the phenomenon of positioning pin hook parts when grasping the parts. Abandon the positioning and matching accuracy of pins and holes, but in the process of equipment assembly, due to poor positioning accuracy, another phenomenon will occur, that is, the positioning pins on the mechanical gripper are not aligned with the positioning holes of the workstation equipment, so that the equipment Frequent errors. As shown in Figure 2, when the mechanical gripper grasps thin-walled parts with an inclined angle, if a cylindrical pin is used, there must be a large gap between the cylindrical pin head and the part positioning hole, that is, the diameter A of the part positioning hole must be larger than Only when the diameter B of the cylindrical pin head is larger, the parts can be picked and placed.
Classification broadcast product series Product detailed classification Hexagon bolts (1) Hexagon bolts (1) Hexagon full teeth: GB5783/DIN933 (2) Hexagon half teeth; GB5782/DIN931 (3) Class B flange hexagon bolts: GB5787 (4) Joint bolts: GB798/DIN444 (5) Welding bolts for manual welding: GB902 square neck bolts (1) Half round head square neck bolts: GB14/DIN603 (2) Small half round head square neck bolts: GB12 (3) Half round head low square neck bolts: GB801 Remarks: Square neck bolts and carriage bolts Hexagon socket head cap screws (1) Hexagon socket head cap screws: GB70/DIN912 (2) Hexagon socket flat end set screws: BG70/DIN913 (3) Hexagon socket head set screws: GB78/DIN914 ( 4) Countersunk head socket head socket head set screw: GB79/DIN915 (5) Hexagon socket socket head set screw: GB80/DIN916 (6) Hexagon socket head countersunk head screw: DIN7991 (7) Hexagon socket head thin head screw: DIN7984 ( 8) Plug screw: ISO7379 machine screw (1) Slotted cylinder head screw: GB65/DIN84 (2) Slotted pan head screw: GB67/DIN85 (3) Slotted countersunk head screw: GB68/DIN963 (4) Slotted Large flat head screw (5) Cross recessed small pan head screw: GB823 (6) Cross recessed large flat head screw (7) Cross recessed pan head screw: GB818/DIN7985 (8) Cross recessed countersunk head screw: GB819/DIN965 (9 ) Cross recessed countersunk head screw: GB820/DIN966 thread and stud (2) Stud bolt-bm=1d: GB897/DIN938 (3) Stud bolt-bm=1.25d: GB898/DIN939 (4) Stud head Bolt-bm=1.5d: GB899 (5) Stud bolt-bm=2d: GB900 (1) Tooth bar: GB15389/DIN976 (6) Equal length stud: GB901/DIN976
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