1. Classification according to process attributes
(1) Stamping die A die that separates materials along a closed or open contour. Such as blanking die, punching die, cutting die, cutting die, trimming die, cutting die, etc.
(2) Bending the die makes the blank or other blanks bend and deform along a straight line (bending line), thus obtaining a die with a certain angle and shape.
(3) Drawing die is a die that makes the blank of sheet metal into an open hollow part or further changes the shape and size of the hollow part.
(4) The forming die is a die for directly copying and forming a blank or semi-finished workpiece according to the shapes of the male die and the female die, and the material itself only produces local plastic deformation. Such as expanding die, necking die, flaring die, wavy forming die, flanging die, shaping die, etc.
2. Classification according to the degree of process combination
(1) Single-process stamping die A die that only completes one stamping process in one stroke of the printing machine.
(2) The compound die has only one station, and in one stroke of the press, two or more stamping processes are completed at the same station at the same time.
(3) The progressive die (also called the continuous die) has two or more stations in the feeding direction of the blank, and in one stroke of the press, two or more stamping processes are continuously completed at different stations.
3. Classification according to the deformation characteristics of materials
Typical mold structure:
Fig. 1. 1.2 is a single-process blanking die with a guide post and a guide sleeve. It consists of an upper die and a lower die. The upper die consists of a die handle 5, an upper die holder 3, a guide sleeve 2, a punch 10, a backing plate 8, a fixing plate 7, a discharging plate 14, screws, pins and other parts. The lower die consists of lower die holder 17, guide post 1, female die1,guide plate 15, support plate 18, screws, pins and other parts. The upper die is installed on the slider of the press through the die handle 5, and moves up and down with the slider, so it is called the movable part. The lower die is fixed on the workbench of the press through the lower die seat, so it is also called a fixed part.
Generally, molds consist of two types of parts:
One kind is process parts, which directly participate in the completion of the process and have direct contact with the blank, including work parts, positioning parts, unloading pressing parts and so on.
One kind is structural parts, which do not directly participate in the completion of the process, nor directly contact with the blank, but only play the role of ensuring the completion of the mold process, or improve the mold function, including guide parts, fasteners, standard parts and other parts, as shown in table 1. 1.3. It should be pointed out that not all stamping dies must have the above six parts, especially single-process dies, but the working part and the necessary fixed part are indispensable.
Stamping Die —— Present Situation and Development of Stamping Die
According to archaeological findings, as early as more than 2,000 years ago, the existing stamping dies in China were used to make bronzes, which proved that the achievements of ancient stamping forming and stamping dies in China were leading in the world. 1953 Changchun No.1 automobile factory set up a stamping die workshop for the first time in China, and the factory began to manufacture automobile panel dies in 1958. China began to produce fine blanking dies in 1960s. After a long road of development, China has now formed more than 30 billion yuan (excluding statistics from Hong Kong, Macao and Taiwan, the same below). ) the production capacity of various stamping dies.
I. Market Situation of Stamping Die
China's stamping dies have made great progress in quantity, quality, technology and ability, but there is still a big gap compared with the national economic demand and the world advanced level. Every year, a large number of large-scale, precise, complex and long-life high-end molds are still imported, especially for the panel dies of mid-to high-end cars, which are still mainly imported. Some low-grade simple stamping dies have been oversupplied and the market competition is fierce.
According to the statistical data released by China Mould Industry Association, the total output of stamping dies in China in 2004 was about 22 billion yuan, of which 75 million dollars was exported, about 620 million yuan.
According to the statistics of China Customs, in 2004, * * imported stamping dies from China amounted to 56,654.38 billion US dollars, about 4.66 billion yuan. From the above figures, it can be concluded that the total size of the stamping die market in China in 2004 was about 26.66 billion yuan. Among them, the domestic market demand is 26.04 billion yuan, the total supply is about 265.438+38 billion yuan, and the market satisfaction rate is 82%. In the above overview of supply and demand, there are several specific situations that must be explained: First, most imported molds are large precision molds with high technology content, while most export molds are middle and low-grade molds with low technology content, so the market satisfaction rate of middle and high-grade molds with high technology content is lower than that of stamping molds, and the development of these molds has lagged behind the production of stamping parts, while the market satisfaction rate of middle and low-grade molds with low technology content is higher than that of stamping molds; Secondly, the mould price in China is much lower than that in the international market, so it has a good prospect in the international market. In 2005, the export of stamping dies reached $65.438+0.46 billion, an increase of 94.7% over 2004. Third, Hong Kong-funded, Taiwan-funded and foreign-funded enterprises have developed rapidly in China in recent years. There are no exact statistical data for a large number of stamping dies produced and used by these enterprises, so they cannot be included in the above figures.
Second, the level of stamping die
In recent years, the level of stamping dies in China has been greatly improved. Large stamping dies have been able to produce a set of dies weighing more than 50 tons. The panel dies for mid-range cars can also be produced in China. Many domestic enterprises have produced multi-position progressive dies with accuracy of 1~2μm and service life of about 200 million times. Fine dies with surface roughness Ra≤ 1.5μm, large-size (φ≥ 300 mm) fine dies and medium plate fine dies have also reached a fairly high level in China.
1. Present situation of mould CAD/CAM technology
The development of mould CAD/CAM technology in China has a history of more than 20 years. The precision mould CAD/CAM system completed by Huazhong University of Science and Technology and Wuhan 733 Factory in 1984 * * is the first self-developed mould CAD/CAM system in China. The cold stamping die CAD/CAM system, which was jointly completed by Huazhong University of Science and Technology and Beijing Mould Factory, is the first cold stamping die CAD/CAM system developed by China. The CAD/CAM system of cold stamping die developed by Shanghai Jiaotong University was also completed in the same year. Since 1990s, domestic automobile industry has started to adopt CAD/CAM technology to design and manufacture molds. The National Science and Technology Commission 863 plans to use Dongfeng Motor Company as a CIMS application demonstration factory and Huazhong University of Science and Technology as a technical support unit. The developed CAD/CAPP/CAM integrated system for automobile panel dies passed the appraisal in early 1996. During this period, FAW and Cheng Fei Automobile Mold Center introduced workstations and CAD/CAM software systems, which were applied to mold design and manufacturing, and achieved remarkable benefits. 1997 faw introduced CAE software for computer simulation of sheet metal forming process and began to use it in production.
Since the 20th century, CAD/CAM technology has been gradually popularized, and now all stamping die enterprises with certain production capacity basically have CAD/CAM technology. Some key enterprises also have various CAE capabilities.
Mold CAD/CAM technology can significantly shorten the mold design and manufacturing cycle, reduce production costs and improve product quality, which has become the consensus of people. During the "Eighth Five-Year Plan" and "Ninth Five-Year Plan" period, a large number of mold enterprises popularized computer drawing technology, and the utilization rate of NC machining became higher and higher, and a considerable number of CAD/CAM systems were successively introduced. For example, UG of American EDS Company, Pro/Engineer of American Parametric Technology Company, CADS5 of American CV Company, DOCT5 of British DELCAM Company, CRADE and space-E of Japanese HZS Company, Cimatron of Israeli Company, AutoCAD and CATIA and Euclid-IS of French Marta-Daravision Company, etc. have also been introduced one after another. CAD/CAM technology is widely used by domestic automobile panel die manufacturers. Two-dimensional CAD has been realized in the design of DL drawing and die structure drawing, and most enterprises have transitioned to three-dimensional, and the production of general drawing has gradually replaced the production of part drawing. Moreover, the parametric design of mold has also begun to move towards the technical development field of a few mold manufacturers.
In stamping CAE software, in addition to imported software, Huazhong University of Science and Technology, Jilin University and Hunan University have all developed advanced software with independent intellectual property rights, which has been successfully applied in production practice and produced good benefits.
Rapid prototyping technology (RP) is combined with traditional rapid and economical molds to rapidly manufacture large-scale automobile panel molds, which solves the problems of low mold precision, low parts precision and difficult sample making of the original low-melting-point alloy molds, realizes rapid mold manufacturing based on 3D CAD models, ensures the parts precision, and provides a guarantee for the development of new models in the automobile industry and the rapid trial production of automobile bodies. It marks the application of RPM technology in large automobile body.
Around the trial production of automobile body and the rapid manufacturing of large panel dies, some new rapid prototyping methods have appeared in recent years, such as dieless multi-point forming, laser shock, electromagnetic forming and so on, which have been applied to production at present. Both show the advantages of reducing costs and improving efficiency.
2, mold design and manufacturing capacity
Under the correct guidance of the national industrial policy, after decades of efforts, the design and manufacturing capacity of stamping dies in China has reached a high level, and many modern design and manufacturing technologies, including information engineering and virtual technology, have been applied in many die enterprises.
Even so, there is still a big gap between the design and manufacturing capacity of stamping dies in China and the market demand and the international advanced level. These are mainly manifested in high-end cars and large and medium-sized automobile panel dies and high-precision stamping dies, and there is a big gap in design, processing technology and ability. The automobile panel die has the characteristics of great difficulty in design and manufacture, high quality and high precision, and can represent the level of the panel die. Although the design and manufacturing methods and means have basically reached the international level, and the mold structure and function are close to the international level, which has made a big step forward in the localization process of automobile molds, there is still a certain gap compared with foreign countries in manufacturing quality, accuracy and manufacturing cycle.
Multi-station progressive die and multifunctional die are the key varieties in the development of precision die in China, which indicates the advanced level of stamping die technology. The representative is the multifunctional die for precise automatic valve plate of iron core, which basically reaches the international level.
However, compared with foreign multi-station progressive dies, there is still a certain gap in manufacturing accuracy, service life, die structure and function.
The manufacturing technology of automobile panel dies has been continuously improved and perfected, and the use of high-precision and efficient processing equipment has become more and more extensive. High-performance five-axis high-speed milling machines and three-axis high-speed milling machines have been used more and more. The application of NC and DNC technology is becoming more and more mature, which can be used for bevel machining and ultra-precision machining. All these have improved the machining accuracy of the mold surface, improved the mold quality and shortened the mold manufacturing cycle.
Die surface strengthening technology has also been widely used. The ion nitriding technology with mature technology, no pollution and moderate cost is more and more recognized, and carbide coating treatment (TD treatment) and many plating (coating) technologies are more and more used in stamping dies. Vacuum treatment technology, full mold casting technology and cutting edge surfacing technology are becoming more and more mature. Laser cutting and laser welding technology have also been applied.
3. Degree and distribution of specialization
The degree of specialization of mold industry in China is still relatively low, and the proportion of self-production and self-marketing is too high. Generally, the proportion of foreign dies produced and sold is 30%, and the proportion of domestic stamping dies produced and sold is 60%. This has many adverse effects on specialization. At present, the die with high technical requirements and large investment has a high degree of specialization, such as panel die, multi-position progressive die and fine blanking die. However, the specialization of general molds is low. Due to the high self-proportioning, the productivity distribution of stamping die basically follows the productivity distribution of stamping parts. However, the distribution of highly specialized automobile panel dies and multi-position and multi-function precision dies does not follow the distribution of stamping capacity, but often depends on the decisions of major investors. For example, Sichuan automobile panel dies have a large capacity, while Jiangsu has a strong precision stamping capacity, and most die users are not locals.
Third, the development focus and prospect of stamping die
The choice of development focus should be determined according to market demand, development trend and present situation. It can be described by product focus, technology focus and other focus respectively.
1, the development focus of stamping die products
There are seven categories of stamping dies, some of which are called by their customers. At present, it is urgent to develop automobile panel dies, multi-functional multi-position progressive dies and fine blanking dies. There is a great contradiction between production and demand of these molds now, and their development prospects are very good.
The development focus of automobile panel dies is the medium and high-grade car panel dies with high technical requirements, especially the outer panel dies. Stamping dies, large-scale multi-position progressive dies and continuous dies for high-strength plates and unequal thick plates will develop rapidly in the future.
The development of multi-functional multi-station progressive die focuses on high precision, high efficiency and large-scale long-life progressive die.
The focus of fine blanking die development is the large-scale fine blanking die for thick plate, and its accuracy is constantly improving.
2. The development focus of stamping die technology
In the future, the development trend of mold technology is mainly information, high speed and high precision. Therefore, in terms of design technology, the development focus is to vigorously promote the application of CAD/CAE/CAM technology to continuously improve efficiency, especially the computer simulation analysis technology of sheet metal forming process. Mould CAD/CAM technology should develop in the direction of humanization, integration, intelligence and networking, and improve the professional level of mould CAD/CAM system.
In order to improve the application level of CAD, CAE and CAM technology, it is very important to establish a complete mold database, develop an expert system and improve the practicability of the software. In terms of machining technology, the development focus is on high-speed machining and high-precision machining. At present, high-speed machining mainly develops high-speed milling, high-speed grinding and polishing, high-speed electrical machining and rapid die making technology. At present, high-precision machining is mainly to develop all kinds of precision machining of die parts with precision below 1μm and surface roughness Ra ≤ 0. 1 μ m. Improving the standardization of dies and improving the production and supply of die standard parts is also one of the key points in the development of stamping die technology.
In order to improve the service life of stamping die, various technologies such as die surface strengthening and superhard treatment are also the focus of development.
It is the focus of stamping die technology development to form an all-round solution of digital die manufacturing, system integration, reverse engineering, rapid prototyping/die manufacturing and computer-aided application technology, provide die development and engineering services, and comprehensively improve the enterprise level and die quality.
3. Other development priorities and prospects
Other development priorities and prospects are very rich in connotation. Here we only analyze three aspects: management, specialization and standardization, and industry adjustment.
Enterprise management is a systematic project, a science and technology. Compared with mold enterprises in developed countries, in a sense, our management is even behind our technology. Therefore, it is very important to improve the management level and the task is heavy. At present, there are many management forms of mold enterprises, and each form has its own adaptive object. However, doing a good job in information construction and gradually realizing information management have become the development direction, and the industry has also recognized this.
4. Current problems
Due to historical and institutional reasons, the level of specialization and standardization of molds in China has been very low, and the degree of specialization of stamping molds is lower than that of plastic molds and die-casting molds. This has hindered the development of stamping die to some extent. According to the specialization degree of molds at home and abroad,
1) Mold production is independent of other products, specializing in the production of molds for external supply;
2) Specializing in the production of a certain type of mold (such as stamping mold) according to the mold type;
3) In a certain mold, according to its service object or mold technology and size, select a certain mold (such as automobile panel mold, multi-station progressive mold, fine blanking mold, etc.). ) professional production;
4) Specializing in the production of some parts in the mold (such as mold base, punch, elastic element, etc.). ) is a mold manufacturing enterprise;
5) Carry out specialization and cooperation according to the process. For example, at present, companies specializing in mold design, enterprises specializing in cavity machining or electro-machining cooperation, enterprises specializing in measurement or heat treatment and enterprises specializing in polishing business have promoted the development of mold industry. However, the road to specialization is still far away, and we must speed up the process to adapt to the situation. Therefore, this is also the focus of development.