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Stamping Die

Stamping die is a special process equipment for processing materials (metal or non-metal) into parts (or semi-finished products) in cold stamping processing, called cold stamping die (commonly known as cold stamping die). Stamping is a pressure processing method that uses a mold installed on a press to apply pressure to the material at room temperature to cause separation or plastic deformation to obtain the required parts.

Stamping is a pressure processing method that uses a stamping die to apply pressure to the material on a press to cause plastic deformation or separation to obtain parts of the required shape and size at room temperature. This processing method is usually called cold stamping.

Stamping die is a process equipment for processing materials into workpieces or semi-finished products in stamping processing, and is the main process equipment for industrial production. The use of stamping dies to produce parts can use mass-produced rolled steel plates or steel strips as blanks in metallurgical plants, and does not need to be heated in production. It has the advantages of high production efficiency, good quality, light weight and low cost. Cold stamping products can be seen everywhere in airplanes, automobiles, tractors, motors, electrical appliances, instruments, meters and daily necessities. Such as: stainless steel lunch boxes, dinner plates, cans, car covers, bullet shells, aircraft skins, etc. According to incomplete statistics, stamping parts account for about 60% in the automobile and tractor industries, about 85% in the electronics industry, and about 90% in daily hardware products.

The press is a machine used to perform pressure processing on the material placed in the mold. The commonly used presses for stamping are mechanical presses and hydraulic presses.

A stamping part often needs to go through multiple stamping processes to complete. Due to the different shapes, dimensional accuracy, production batches, raw materials, etc. of stamping parts, the stamping process is also diverse, but it can be roughly divided into two categories: separation process and forming process.

  • (1) Separation process The process of separating stamping parts and sheet metal from each other along a certain contour line. For example: cutting, punching, blanking, cutting, trimming, etc.
  • (2) Molding process The material is plastically deformed without breaking, so as to obtain a process that requires a certain shape, size and accuracy of parts. For example: bending, deep drawing, flanging, bulging, shaping, etc.

The Composition Of The Stamping Die

Although the structure and complexity of various stamping dies are different, and the parts that make up the mold are diverse, they are always divided into upper and lower dies. The upper die is generally fixed on the slider of the press by a die handle, and moves up and down along the press guide rail together with the slider, and the lower die is fixed on the worktable of the press. The classification and functions of the components of the stamping die are as follows:

1.Working parts

It is a part that directly contacts the stamping material and applies pressure to it to complete the stamping process. The working parts of the die include a punch, a die, and a punch and die, which are also called forming parts, which are the most important parts in the die.

2.Positioning parts

It is to determine the correct position of the material or process parts in the die, so that the stamping parts can obtain qualified quality requirements. The positioning parts belonging to the feeding guide include guide pins, guide plates, side pressure plates, etc.; the positioning parts belonging to the feeding distance include starting stop pins, stop pins, guide pins, side edges, etc.; belong to block materials or The positioning parts of the process parts include positioning pins, positioning plates and so on.

3.Pressing and unloading parts

This kind of parts plays the role of pressing materials, and ensures that the waste or stamping parts stuck on the punch and the cavity L are unloaded or pushed (ejected) out to ensure that the stamping work can continue.
The function of the holding plate is to prevent the blank from moving and bouncing. The function of the unloading board is to facilitate the discharging and cleaning of waste materials. Usually, the unloading device refers to the removal of stamping parts or waste from the punch; the pushing and ejecting device refers to the removal of the stamping or waste from the die. Generally, the one installed in the upper mold is called the pusher: the one installed in the lower mold is called the top.

4.Guide parts

Its main function is to ensure the accuracy of the mutual position between the male mold and the female mold, and to ensure that each part of the mold maintains a good state of motion. It is composed of a guide post, a guide sleeve, and a guide plate.

5.Supporting parts

It connects and fixes the above-mentioned various parts on a certain position, or connects the die with a press. It is the basic part of the die. Mainly include upper mold base, lower mold base, fixed plate, backing plate, mold handle, etc.

6.Fastening parts

Mainly used to fasten and connect various die parts, such as various bolts, screws, round pins, etc. The above-mentioned guide parts and supporting parts are called a mold base after being assembled. The mold base is the skeleton of the entire mold, all parts of the mold are fixed on it, and bear all the loads in the stamping process. The upper mold base of the mold base is connected with the press slide block through a mold handle, and the lower mold base is fixed on the work table of the press with a screw pressing plate. The guide device of the mold base between the upper and lower molds maintains its precise position to guide the movement of the punch and ensure the uniformity of the gap during the stamping process. The mold base and its components have been standardized, and certain technical conditions have been specified for it.

The mold base is divided into a guide column mold base and a guide plate mold base. The most widely used is the mold base that uses guide posts and guide sleeves as guide devices. According to different feeding methods, this standard mold base includes a rear guide pillar mold base, a middle guide pillar mold base, a diagonal guide pillar mold base and a four guide pillar mold base. When designing the mold, you can select it correctly according to the design requirements of the convex and concave molds. The size of the mold base can be directly selected from the standard by the perimeter size of the die.

The Classification Of Stamping Die

There are many forms of stamping dies, which can generally be classified according to the following main characteristics:

Classification according to the nature of the process

  • (1) Blanking die A die that separates materials along a closed or open outline. Such as blanking die, punching die, cutting die, slitting die, trimming die, cutting die, etc.
  • (2) Bending mold It is a mold that makes the sheet blank or other blanks bend and deform along a straight line (bending line) to obtain a certain angle and shape of the workpiece.
  • (3) Stretching mold is a mold for making a blank sheet into an open hollow part, or to further change the shape and size of the hollow part.
  • (4) Forming mold is a mold that directly replicates the blank or semi-finished workpiece according to the shape of the convex and concave molds, and the material itself only produces local plastic deformation. Such as bulging molds, necking molds, flaring molds, undulating forming molds, flanging molds, shaping molds, etc.

Classification according to the degree of process combination

  • (1) Single-process mold In one stroke of the press, only one stamping process mold is completed.
  • (2) The compound mold has only one station. In one stroke of the press, two or more stamping processes can be completed at the same time on the same station.
  • (3) Progressive die (also called continuous die) In the feeding direction of the blank, there are two or more stations. In one stroke of the press, two or two passes are completed successively at different stations. Die for more than one stamping process.
  • (4) The transfer mold combines the characteristics of single-process mold and progressive mold. The robot transfer system is used to realize the rapid transfer of the product in the mold, which can greatly improve the production efficiency of the product, reduce the production cost of the product, save the material cost, and quality Stable and reliable.

China’s development status

In recent years, the level of stamping dies in China has been greatly improved. Large-scale stamping dies have been able to produce a single set of dies with a weight of more than 50 tons. Cover molds for mid-range cars can also be produced in China. The multi-station progressive die with an accuracy of 1~2μm and a life span of about 200 million times has been produced by many companies in China. The fine blanking dies with surface roughness reaching Ra≦1.5μm, large-size (Φ≧300mm) fine blanking dies and medium-thick plate fine blanking dies have also reached a very high level in China.

Mold CAD/CAM technology status

The development of China’s mold CAD/CAM technology has a history of more than 20 years. The fine blanking die CAD/CAM system jointly completed by the former Huazhong Institute of Technology and Wuhan 733 Factory in 1984 is the first self-developed die CAD/CAM system in China. The CAD/CAM system for cold stamping dies jointly completed by Huazhong Institute of Technology and Beijing Mould Factory in 1986 is the first CAD/CAM system for stamping dies developed by China itself. The cold die CAD/CAM system developed by Shanghai Jiaotong University was also completed in the same year. Since the 1990s, CAD/CAM technology has been adopted in the mold design and manufacturing of China’s automobile industry. The National Science and Technology Commission 863 plans to use Dongfeng Motor Corporation as a CIMS application demonstration plant, with Huazhong University of Science and Technology as the technical support unit. The CAD/CAPP/CAM integrated system for automobile body and panel molds developed by the Huazhong University of Science and Technology passed the appraisal in early 1996. During this period, FAW and Chengfei Automobile Mould Center introduced workstations and CAD/CAM software systems, and applied them in mould design and manufacturing, and achieved significant benefits. In 1997, FAW introduced CAE software for computer simulation of sheet metal forming process and started to use it in production.

Since the beginning of the 21st century, CAD/CAM technology has gradually become popular. Now stamping die companies with a certain production capacity basically have CAD/CAM technology. Some of the 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 a consensus. During the “Eighth Five-Year Plan” and “Ninth Five-Year Plan” period, a large number of mold companies have popularized computer graphics technology, and the utilization rate of CNC machining has become higher and higher, and a considerable number of CAD/CAM systems have been introduced one after another. For example, UG from EDS in the United States, Pro/Engineer from Parametric Technology in the United States, CADS5 from CV in the United States, DOCT5 from DELCAM in the United Kingdom, CRADE and space-E from HZS in Japan, Cimatron from Israel, and software such as AutoCAD and CATIA have also been introduced. And special software such as Euclid-IS used by French Marta-Daravision company for automobile and panel molds. CAD/CAM technology is generally adopted by Chinese automobile panel mold production enterprises. Both the design of DL drawing and the design of mold structure drawing have realized two-dimensional CAD. Most companies have already transitioned to three-dimensional, and general drawing production has gradually replaced part drawing production. And the parametric design of molds has also begun to move towards the field of technology development by a few mold manufacturers.

In terms of stamping and forming CAE software, in addition to the imported software, Huazhong University of Science and Technology, Jilin University, Hunan University, etc. have all developed high-level software with independent intellectual property rights, and they have been successfully applied in production practice. Good benefits.

Rapid prototyping (RP) is combined with traditional rapid economic molds to quickly manufacture large-scale automobile panel molds, which solves the problems of low melting point alloy molds relying on sample casting molds, low mold accuracy, low precision of parts, and difficult sample production. , To achieve rapid mold manufacturing based on the three-dimensional CAD model, and to ensure the accuracy of the parts, for the development of new models in the automotive industry, rapid trial production of car bodies to provide guarantees for the production of cover parts, it marks the application of RPM to automobiles The trial-manufacture of large-scale car body panels has been successful.

Some new rapid prototyping methods have emerged in recent years around the trial production of automobile bodies and the rapid manufacturing of large-scale cover molds, such as the moldless multi-point molding and laser shock and electromagnetic molding technologies that have been applied in production. They all show the advantages of reducing costs and improving efficiency.

Mould design and manufacturing capacity status

Under the correct guidance of the national industrial policy, after decades of hard work, China’s stamping die design and manufacturing capabilities have reached a relatively high level. Many modern design and manufacturing technologies, including information engineering and virtual technology, have been applied in many mold companies.

Even so, China’s stamping die design and manufacturing capabilities still lag far behind the market demand and the international advanced level. These are mainly manifested in the high-end car and large and medium-sized automobile panel molds and high-precision die, both in terms of design, processing technology and capabilities, there is a big gap. Car cover molds have the characteristics of difficult design and manufacturing, and high quality and precision requirements, which can represent the level of cover molds. Although the design and manufacturing methods and means have basically reached the international level, and the mold structure and function are also close to the international level, it has made a big step forward in the process of localization of car molds. However, in terms of manufacturing quality, precision, and manufacturing cycle, it has Compared with foreign countries, there is still a certain gap.

Multi-station progressive die and multi-function die, which mark the advanced level of die technology, are the precision die varieties that China focuses on development. The representative one is the multi-function mold of the iron core precision automatic valve disc integrating mechatronics, which has basically reached the international level.

However, compared with foreign multi-station progressive molds, there is still a certain gap in manufacturing accuracy, service life, mold structure and function.

Automobile panel mold manufacturing technology is constantly improving and perfecting, and the use of high-precision and high-efficiency processing equipment is becoming more and more widespread. High-performance five-axis high-speed milling machines and three-axis high-speed milling machines have been increasingly used. The application of NC and DNC technology is becoming more and more mature and can be used for inclination processing and super finishing. These have improved the precision of mold surface processing, improved the quality of the mold, and shortened the mold manufacturing cycle.

Mold surface strengthening technology has also been widely used. Ion nitriding technology with mature technology, pollution-free and moderate cost is increasingly recognized, and the application of carbide coating treatment (TD treatment) and many plating (coating) technologies on stamping dies is increasing. Vacuum processing technology, solid casting technology, and edge surfacing technology are becoming more mature. Laser cutting and laser welding technology have also been applied.

Degree of specialization and distribution

The degree of specialization of China’s mold industry is still relatively low, and the proportion of self-produced and self-made molds is too high. The self-produced and self-made ratio of foreign molds is generally 30%, and the self-produced and self-made ratio of Chinese stamping dies is 60%. This has had a lot of adverse effects on specialization. Nowadays, molds with high technical requirements and large investment have a higher degree of specialization, such as cover molds, multi-station progressive dies and fine blanking dies. The general degree of specialization of the die is low. Due to the high proportion of self-matching, the distribution of stamping die production capacity basically follows the distribution of stamping parts production capacity. However, the distribution of highly specialized automotive panel molds and multi-station, multi-functional precision stamping professional production companies does not follow the distribution of stamping capabilities, but often depends on the decision of major investors. For example, Sichuan has a relatively large capacity for automobile panel molds, and Jiangsu has a relatively strong capacity for precision punching dies, and most of the mold users are not local.

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