text
Due to the trend of light weight, high performance and energy saving of transportation tools, Tube Hydroforming or Internal High Pressure Forming technology has been greatly attracting attention from industry and academia since the 1990s. Development, has become one of the mainstream manufacturing technologies of the international automotive industry, including: Germany double B, VW, AUDI, OPEL, US GM, FORD, CHRYSLER, Japan TOYOTA, HONDA, NISSAN, SUBARU, MAZDA, MITSUBISHI, Korea KIA, Hyundai has been put into production or trial production. The main applications are chassis parts, body structural parts and exhaust system components. The application in other industries is also expanding, and the prospects are very broad. Pipe fitting hydroforming technology has: light weight / energy saving, integrated product, good rigidity, improved product performance / precision and innovation, and can reduce the number of semi-finished parts in the production process, reducing welding, machining and product assembly After the processing, it effectively reduces the production cost and shortens the processing cycle.
Technical principle
Pipe fitting hydroforming technology is suitable for hollow structural pipe fittings with different thickness and shape. As the name suggests, the pipe is first placed in a shaped mold. High pressure fluid is added inside the pipe (currently mainly water), with axial pressure compensation. The tube material is pressed into the mold cavity to form the tube. The hydraulic pressure required for its formation is generally about 2000 Bar, and even up to 4000 Bar under special conditions. Applicable materials and application range: Excellent extensibility is the key to hydroforming. In principle, the materials suitable for cold forming processing are suitable for pipe forming hydroforming technology. At present, mainly: carbon steel, special steel, stainless steel, aluminum Alloys, copper alloys, etc. are dominant.
2. Technical characteristics
The application of high pressure technology inside the pipe can reduce the number of structural parts, weld passes and shorten the assembly time, achieving the goal of reducing weight and reducing costs. The advantages vary from product to product, compared to the advantages of traditional production technology. include:
1. Lightening weight: compared with turning and boring, the hollow shaft of hydraulic forming of pipe fittings can be reduced by 40%~50%, and some even up to 75%; if compared with stamped welded parts, the hydraulic forming of pipe fittings on automobiles Hollow structural parts can be reduced by 20% to 30%.
2. Reducing the number of semi-finished parts: Large and complex 3D geometry workpieces such as engine brackets, top cover frames, and door frames can be machined at one time during the forming process. Compared with stamped welded parts, the number of sub-frame parts has been reduced from 6 to 1; the number of radiator bracket parts has been reduced from 17 to 10.
3. Reducing the cost of the mold: The hydraulic forming of the pipe fitting usually only requires one set of molds, and the stamped and welded parts are welded by a plurality of stamping parts, so multiple sets of stamping dies are required.
4. Reduce the amount of subsequent machining and assembly welding: Take the radiator bracket as an example, the number of welding points is reduced from 174 to 20, the number of manufacturing passes is reduced from 13 to 6, and the production efficiency is increased by 66%.
5. Improve strength, rigidity and fatigue strength: The liquid has a cooling effect during the forming process, so that the workpiece is "cold-strengthened" to obtain a higher workpiece strength than the general press processing. Taking the radiator bracket as an example, the vertical direction is increased by 39%; the horizontal direction is increased by 50%.
6. Reduce production costs: Schuler Hydroforming analyzes the products that have been applied. The cost of hydraulically formed parts is 15% to 20% lower than that of stamped and welded parts, and the cost of molds is reduced by 20% to 30%.
7. Innovative: Overcoming traditional process limitations and applying to new product design and development.
3. Status of industrial applications at home and abroad
From the application development history of the past 10 years, as shown in Figure 2, the automotive industry is undoubtedly the largest application industry, and the products are also expanded from the instrument panel bracket, engine bracket, radiator bracket, etc. to the frame rails ( Frame Rail), Sub Frame and other projects; In addition, in other vehicle industries, the frame and rear arm of the locomotive (Rear Arm) were officially applied in Harley, Yamaha and other off-road vehicles in 2002. In the model, the bicycle frame, rocker arm and upper tube also have the track of the manufacturer's application. As for faucets, valve products, spherical containers, superconducting accelerators, pipe fittings and other products, hydraulic forming technology is also used to achieve its quality and consumer demand. The following is a detailed description of the application related to hydroforming technology.
The application manufacturers on locomotive hydroforming components are Harley and YAMAHA. In terms of YAMAHA, its hydroforming technology is mainly applied to the rocker ngarm of the 2002 WR250F (four-stroke off-road vehicle) to reduce weight and increase rigidity. As for the application of Harley's company, the Harley's Product Development Centre applied hydroforming technology to the frame of the 2002 V-Rod model to form a weld-free and rigid The structure adopts a 1.5-inch pipe fitting to form a complex three-dimensional structure by high-pressure forming after pre-bending.
4. Research and development trend of pipe fitting hydroforming technology
The current research focuses on how to improve the competitiveness of hydroforming technology, including: reducing capital expenditures (initial equipment investment), increasing productivity and output, improving material utilization, process rationalization, reducing non-performing rates, and developing integrated hydroformed parts. The main research and development projects are as follows:
4.1 Tube Formability Analysis Technology
It is mainly the establishment of basic data and experimental methods of material properties, including: Bulging test, flow stress (K, n value), and tube forming limit diagram (FLD).
4.2 Application of CAD/CAE technology for pipe fitting hydroforming
In order to reduce costs, shorten product development time and increase development success rate, CAD/CAE is becoming more and more important for new hydroforming technology. The numerical simulation can accurately reflect the hydroforming process of the pipe fittings, predict the forming defects, show the mold sticking and forming conditions, and calculate the wall thickness distribution. Moreover, the relationship between internal pressure and axial displacement can be conveniently adjusted, and the influence on the forming defects and wall thickness distribution can be studied to obtain the optimal loading curve. Therefore, CAE simulation of pipe fitting hydroforming has also received attention from researchers and industry in various countries.
5. Development trend of hydroforming industry
In view of the current application market of hydroforming technology, the automotive industry is undoubtedly the largest development market in the future. The most successful application of hydroforming technology should be automotive chassis. The main reasons for its popularity are high rigidity, high dimensional accuracy and stability, corrosion resistance, low workpiece count, simplified process and reduced cost. As a result, the demand for tube hydroforming components has increased dramatically dramatically. This demand will force hydroforming equipment producers and chassis system suppliers to accelerate the development of related technologies. The car body architecture of the future North American market may be replaced by hydroformed components, including:
(1) Government Regulations – Corporate Average Fuel Economy (CAFE): This regulation has made North American automakers nervous. In a time when a gallon of oil cost less than a bottle of drinking water, consumers are reluctant to give up sacrificing car spaciousness, performance or safety to save fuel. However, when CAFE regulations conflict with customer expectations, engineers must develop more fuel efficient and lighter weight vehicles.
(2) Safety: More and more impact test standards, coupled with customer awareness and attention to vehicle safety, have prompted OEMs to improve vehicle safety without sacrificing fuel efficiency.
(3) Vehicle performance: The average speed limit on American highways is 68.5 miles per hour. There are many national highways without speed limits in Europe, and vehicle performance must keep up with customer expectations.
(4) Accelerating into the market: In the past, it took 4-6 years for a new car to be launched from the product concept to the market. The idea of ​​vehicle performance, style and market demand is established as early as the development process. Therefore, the longer the period drags, the more easily the representative concept is outdated, the higher the market risk, and the unfavorable products are sold in the market. In order to ensure the success of vehicle vehicles in the future, OEMs must shorten this time schedule by 50% or more. Pipe fitting hydroforming technology is one of the key technologies to meet customers' requirements for safety, light weight and timeliness.
(5) According to the survey conducted by the Automotive Research Council of the American Iron and Steel Research Institute, the proportion of hollow light-weight parts in the total number of cars in North America has increased from 10% 15 years ago to 16%, while in medium-sized commercial vehicles. The proportion of big jeep and minivans is even higher. It is estimated that 50% of the structural parts produced in North America in 2004 will be manufactured by pipe fitting hydroforming technology.
(6) Daimler Chrysler estimates that the hydraulic forming components for pipe fittings will grow three times in 2000 compared to 2000.
(7) Dana Corporation (automotive components and international manufacturers) estimates that pipe fittings will account for 50% of automotive chassis components in 2004. To this end, Dana will be in California, Thailand, Brazil and Venezuela in the next five years. At least 12 sets of hydroforming machine production lines have been established in countries such as Argentina.
(8) According to the latest report of Global Trade Consulting, the US automotive hydroforming components were valued at US$730 million in 1998, US$1.6 billion in 2000, and approximately US$1.9 billion in 2001, and in the next 3 years ( In 2002-2004, the average annual growth rate will reach 20%.
Va Distributor,Super Distributor,Super Va Distributor,Best Va Distributor
Yantai Ciso Lubrication Technology Co.,LTD , https://www.cisolubrication.com