Service Hotlinetotal of 13 domestic automotive fastener companies were interviewed and investigated in this survey, and all the companies under investigation have passed the TS16949 system certification. An average car has about 1500 fasteners, and the total bolt assembly time for each car is about 2.5~3.2h. It can be seen that the variety and quality of fasteners have an important impact on the level of the main engine and the quality of the vehicle. This article analyzes the localization of high-strength threaded fasteners and the management of supply quality from the perspective of the production process of high-strength threaded fasteners. Product flow of high-strength threaded fasteners The production process of high-strength threaded fasteners is raw material transformation → cold heading forming → thread processing (thread rolling or thread rolling) → heat treatment → surface treatment → sorting and packaging, generally used above grade 10.9 Thread rolling process after heat treatment. The steel grades commonly used for high-strength bolts of automotive fastener materials are 35 steel, 45 steel, and ML35 steel for grade 8.8 bolts; 35CrMo for grade 10.9 bolts; 40Cr; 35CrMo, 42CrMo, and SCM435 for grade 12.9 bolts. The raw materials for domestic fasteners are basically in the hot-rolled state, while the steel for fasteners produced in Japan and other countries is basically in the state of direct cold heading. Users do not need pretreatment, which can reduce costs from the link. Common failure modes of fastener failure are assembly elongation, fatigue fracture, and delayed fracture. In addition to the material, the quality of cold heading forming and thread processing (thread rolling or thread rolling, tapping) threaded fasteners, forming equipment and thread processing equipment and molds (production process and equipment) are the key factors to ensure their quality. Especially in the state of large-scale and multi-variety supply, automotive fasteners that require high machining accuracy, how to ensure product consistency and defect prevention is one of the problems faced by fastener production. For the cold heading equipment and thread processing equipment of the investigated companies, domestic equipment accounts for about 40%, Taiwan equipment accounts for 50%, and imported (Europe, America, Japan) equipment accounts for about 10%; Partial folding, thread streamline upsetting, tooth wrinkles and cracks, etc. Domestic fastener factories are limited by capital or other reasons, and most of them use domestic equipment and Taiwan equipment to produce fasteners for automobiles. To ensure the dimensional tolerance and geometric tolerance of large-scale production of high-end fastener products, online monitoring should be increased. Means and mold making level. Eliminate unqualified products in production, so as to ensure the assembly quality of OEMs and OEMs. [1] About 80% of the surveyed fastener enterprises have heat treatment equipment, and most of them use Taiwan heat treatment process lines; the process line equipment is a continuous mesh belt furnace with atmosphere protection, and the atmosphere, temperature and process parameters are controlled by a computer. The high-strength fastener industry is a relatively competitive industry. If we want to have a thorough and objective analysis of the technology and market of the high-strength fastener industry, we need to start from the following aspects: domestic high-strength fasteners Industry and Enterprise Competition Pattern High-strength Fastener Industry Industrial Policy High-strength Fastener Product Technical Standards and Regulations my country's High-strength Fastener Product Technology Competition Pattern Dynamics Regarding these six aspects, many domestic research institutions have conducted in-depth research and research, and many institutions have long been engaged in research and research in this industry.
The pull-out type positioning pin and the tie-suspended type positioning pin are in the form of a straight cylindrical shape. The pull-out locating pin is temporarily pulled out from the connected piece of the tooling, and it is in a loose state; the tail of the tie-suspended locating pin is connected with a tie such as iron wire or string to the connecting piece of the tooling. After the locating pin is pulled out, the tie Suspended on tooling. The main disadvantages of the two types of positioning pins are as follows: First, the suspension straps are easy to fall off after long-term wear, and the pull-out positioning pins of the same parts are not convenient for on-site storage and placement, and are usually placed on the nearby ground at will; All kinds of positioning pins are prone to position transfer, forgetting and losing, which affects the reset of the tooling and the subsequent manufacture and assembly of aircraft products.
The positioning pin is a pin designed to accurately position the two adjacent parts of the mold in a mold composed of two or more parts. It can be seen that the positioning pin plays a positioning role, and the mold must be accurately synchronized when it is closed. product, and the positioning pin can make the upper and lower molds play a role in accurate positioning. In the mold design and manufacture of Yueluo, the positioning pin is one of the most common parts. Since it is only used for positioning between parts, few people will pay too much attention to it. In the cold stamping process of Yueluo, the dimensional accuracy of the blanking parts depends on the size of the working part of the punch and the concave die, and the dimensional difference between them constitutes the blanking die gap. Gap is an important process parameter for die design, and its size has a great influence on the quality of the section of the blanking part, the blanking force, and the life of the die. If the gap is too large, punching burrs will appear in punching; if the gap is too small, secondary cracks will occur in the section and extrusion burrs will appear, which will make the quality of the section after punching unsatisfactory, and a reasonable gap will not only help the punching section. The improvement of the quality also contributes to the improvement of the lifespan of the 7-pack.
At present, most of the thread locking structures use an integral nut and a matching external thread screw structure. To remove the nut from the screw rod, it must be completely unscrewed along the screw rod, which is time-consuming and labor-intensive. It is more inconvenient to install.
Nuts are parts that tightly connect mechanical equipment. Through the inner threads, nuts and bolts of the same specification can be connected together. For example, M4-P0.7 nuts can only be connected with M4-P0.7 series bolts (in the nut). Among them, M4 means the inner diameter of the nut is about 4mm, and 0.7 means that the distance between the two threads is 0.7mm); the same is true for American products, for example, a 1/4-20 nut can only be matched with a 1/4-20 screw ( A 1/4 finger nut has an inner diameter of about 0.25 inches, and 20 fingers have 20 teeth in each inch).
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