Some Opinions On The Design And Production Maintenance Of Precision High-Speed Stamping Dies

Some Opinions On The Design And Production Maintenance Of Precision High-Speed Stamping Dies


Precision high-speed stamping production technology is widely used in electronics, automobiles, optics, industrial control, medical and other fields due to its advantages of high efficiency, high quality, consistency, and cost savings. Today, with the highly developed market economy and the rapid development of science and technology, high-speed, precise Stamping technology has been paid more and more attention by many related industries in industrial production, and its high efficiency, reliability and stability have become the main subject of continuous breakthrough and research in continuous stamping technology. Today’s molds are updated and the pace of technological innovation is getting faster and faster. The application of rapid development, automation technology, optical technology, and electromechanical integration technology has also been continuously applied and made breakthroughs. With the advancement of “Made in China 2025”, precision high-speed stamping technology will also usher in an opportunity for benign development.

Precision high-speed stamping die structure and typical production process design

The commonly used structures of precision high-speed stamping dies are two-plate molds, drawer molds (modular molds) and three-plate molds (also known as eight-plate molds)

The two-plate die is designed and fixed on the lower die plate with the functional structure of stamping and stripping. The whole set of die is named after two relatively independent whole. It is characterized by high precision and small stamping stroke, but due to the high processing cost of mold parts, it is largely replaced by three-plate molds.

The drawer mold is evolved from the structure of the three-plate mold. The template is designed as a modular type, and the mold base is designed to adapt to the structure of rapid loading and unloading of multiple modules. Quick die change has become a veritable synonym for its name, but due to its relatively complex structure, high die manufacturing cost, and high requirements for punching parameters, its application is more limited to the stamping production of products with multiple material numbers.

Three-plate die, as the name suggests, is composed of three template groups: upper die, stripper plate, and lower die. It is suitable for stamping production of single material number or small material number. Due to its simple structure, low processing cost, high precision, convenient maintenance and stability It has good characteristics and is adopted by most mold design and stamping manufacturers. Relatively speaking, the three-plate mold can replace the two-plate mold to a certain extent, and the drawer mold has more advantages in the production of multiple material numbers. Therefore, the three-plate mold and the drawer mold have become the mainstream of the precision high-speed stamping industry at this stage.

No matter what kind of mold, its working principle and functional structure are the same. From the working principle, they all drive the relative movement of the die parts through the up and down movement of the punching block and act on the material to be punched, so that they can complete the process of separation or plastic deformation such as punching, bending, etc. From the perspective of functional structure composition The mold is composed of 7 major parts (Fig. 10, the main structure of the field (the mold base template), the carrier of the mold. <2) the guiding element (the guide post and the guide sleeve), the main guiding function of the mold. (3) Pressing and discharging system (stripping plate, Power transmission pin, compression spring, contour sleeve, etc.) Pressing and discharging function of stamping process. (4 Jiang as components (punch, cutting edge, forming, adjustment) Parts, etc.) are directly involved in the core functional parts of material separation and plastic deformation. <5) Positioning elements (positioning needles, guide plates, stripping inserts) ensure the smooth running of the material strip in the mold and the accuracy of the working position of the working elements . (6) Fixed components (screws, positioning pins, pressing blocks, blocks), the relative positions of formwork and formwork, parts and formwork are fixed (7) Auxiliary parts (floating material pin, spring height limit column), material belt auxiliary support and Mold protection and other functions.

Typical stamping process design

There are many types of precision stamping process structures, each with its own process design, production and maintenance characteristics, such as shrapnel bending for contacts, v-CUT forming for pre-breaking, rib stretching for shielding and partitioning, and Mold processes such as tin foot piercing of solder plates, barb blanking for assembly, and needle bar blanking for transmission are typical examples of its production applications. Here, the author introduces several typical mold process structure design schemes for readers’ reference. Figure 2 shows a partial view of the FPC terminal. The shearing surface is the contact part, so the shearing surface should be uniform and higher than the tearing surface without turning over. In the case of limited product pressing material, in addition to local strong pressure, rough cutting + fine cutting is often used in mold design to reduce excessive punching force and internal stress. product impact. Figure 3 shows the blanking of small terminals. Similarly, because the pressing area is too small and the pressing force is insufficient during blanking, the product is pulled out and turned over because the pressing force is less than the punching force during the punching and shearing process. Therefore, the method of fine cutting + rough cutting can also be used to improve the blanking quality when producing such terminals. Furthermore, let’s talk about the design of the bending process. Generally, the mold design personnel know the expansion of the bending. It mainly depends on the bending neutral line of the material. The bending rebound mainly depends on the rebound coefficient of different materials (of course, conditions such as stamping speed, mold lubrication, mold temperature, material texture, etc. will also affect the value of bending parameters) Different materials Neutral line calculation and rebound coefficient, except for special materials, have basically accumulated relatively accurate experience values ​​for designers to choose and calculate. As shown in Figure 4, the basic steps of bending and unfolding are briefly explained. In addition, the size adjustment structure is also a commonly used function of precision stamping dies, especially for multi-pin terminals, the mold parts cannot be absolutely accurate. After stamping, it is difficult to effectively guarantee the dimensional consistency of multi-pin terminals.

The in-mold fine-tuning of each PIN alone can well correct the deviation of the bending size. As shown in Figure 5, in the design, the bending size is set to slightly exceed the upper limit value, and then each pin is fine-tuned to different degrees. In order to achieve the purpose of better consistency of the elastic height and size.

The design of the mold should be a comprehensive technical whole. From the functional requirements of the product, process requirements, assembly and use requirements, and other factors, it is necessary to analyze what effect the mold design needs to achieve to meet the real needs of the product. The mold structure, technology and other means are used to realize the above-mentioned multi-dimensional requirements.Therefore, the mold design itself is a part of the whole of this technology, not the whole. For example, the design of the shrapnel as a contact (Fig. 6) should have contact transmission characteristics in terms of product function, and good contact is required, so how to control the surface roughness of the contact area? Ensure that the contact point is the most reliable place for the shrapnel, which is the key to the mold design. From the process requirements, we should think about how to control the bending expansion, how to prevent the two sides of the contact from being higher than the middle after bending, and how to prevent the bending skew, etc. , From the assembly use, what should be considered is what kind of design process can better improve the fatigue life of shrapnel assembly insertion and extraction. Other influencing factors, material material characteristics, punching speed punch tonnage, electroplating dimensional changes, heat treatment springback, etc. are directly or Indirectly affects the choice of mold design structure, the design layout process, the consideration of the material and processing method of the parts, and the value of design parameters

In the preliminary work of the precision mold design, if the designer can fully think and analyze the mold design according to the above or more dimensions, it will be a matter of course. The designed mold is only the carrier of the designer’s dimension. The requirements can be naturally reflected, so the mold design work is regarded as the overall technology of mold design from multiple dimensions, and the function, process, application and mold characteristics of the entire product can be truly achieved in terms of concept and behavior. High speed and precision.

Use, maintenance and workshop management of precision high-speed stamping dies

A set of high-efficiency, stable, high-quality precision high-speed stamping dies not only needs to analyze and design product functions, processes, applications, and mold design structures in the early stage of design, but also in the normal production process of molds. It directly affects the use effect and life of the mold.

In the use of molds, taking the setting and use of frame conditions as an example, the precise setting and curing of frame conditions parameters play a pivotal role in production efficiency and quality stability. In the case that the special mold and special machine cannot be met, the one-to-one correspondence between the mold and the punch frame mold conditions can well meet the requirements of the curing of the conditional parameters, that is, one mold, one machine, one conditional parameter, and one mold N machine has N conditional parameters. The specific operation is to first select a punch with a suitable tonnage and suitable structure according to the overall requirements of the mold, and then set and fine-tune the theoretical value of the mold parameters to achieve the ideal state of the frame mold adjustment machine and follow up the production quality status to meet the requirements of the process capacity. It is defined as the fixed parameters of the mold in the machine, and then the frame mold production is carried out according to the fixed parameters to achieve the purpose of stable condition curing. In the same way, the conditions of the mold are set on other machines to form a series of fixed conditions. Frame mold condition parameters, these condition parameters provide the most fundamental guarantee for production efficiency and quality stability.

The purpose of mold maintenance is to maintain the excellent and stable production state of the mold and improve the service life of the mold. Generally speaking, the maintenance can be divided into the following four stages. The field inspection stage is to check whether the parts are loose and worn, and repair, polish and lubricate them. and other basic maintenance work. Return the mold to the design state. (2) In the part replacement stage, it is confirmed that the parts are worn and cannot meet the production quality requirements and the relevant blanking parts will be ground when the life of the parts is reached. Replacement of formed parts. (3) Guide precision maintenance The overall precision of the mold comes from the guide elements of the mold. When it is worn to a certain extent. When the required accuracy cannot be provided. It is replaced and precision repaired to restore guiding precision. (4) Mold refurbishment, the template mold base is the main body of the mold, and its overall accuracy will naturally affect the accuracy of the mold. Fitter correction, precision adjustment or even replacement of individual or main templates, to restore the mutual gap, flatness, verticality, etc. of the templates. No matter which stage, the purpose is to maintain and restore the accuracy of the mold. make it in good condition. Here, an important term is involved: die life (number of strokes). For each inspection and maintenance, the corresponding number of punches is the corresponding punching life of each stage. It depends on the material characteristics of the material to be stamped, the material of the mold parts, the stamping speed and other factors. during production process. It is necessary to record the cumulative number of strokes every day, which can better manage the time and frequency of mold maintenance and understand the life status of the mold more freshly.

In terms of mold maintenance, the author believes that we should focus on grasping the root of the problem and analyzing it, such as product size. In general, the idea of ​​maintenance should be based on the basic positioning of the reference hole in the mold to ensure that the reference is correct, and then the analysis of the station or the material belt is carried out. Instead of seeing the blanking gap is unilateral. Just move the cutting edge, reduce the bending gap when the bending is not in place, etc. “When you see the phenomenon, take a countermeasure. The maintenance method is a conditional reaction type, because it is easy to lead to the confusion of maintenance standards, and the more the mold is repaired, the more problems there are. A vicious circle. In addition, the common problem faced by precision high-speed stamping is the problem of chip jumping. I will also briefly talk about the view here. The chip jumping originates from the punched scrap and is brought out of the die surface by external force, and this external force may be atmospheric pressure. The interaction with the vacuum, the viscous force generated by the adhesion of oil stains, the thrust generated by the gas in the mold, and the force generated by the vibration during the stamping process of the mold, and the relative solutions are also various, and the advantages and disadvantages of each are clear. The idea of ​​​​solving the problem is also similar, that is to reduce the generation of this “force”, or create a relative force to offset the external force that causes the chip to jump. From the product, you can change the shape of the scrap to increase the contact area with the mold and increase the frictional force. From the mold structure, you can use the blade coating method, the blade clamping structure, the punch special-shaped structure, the T-shaped blanking hole, etc. From other external forces, you can add a blowing device from top to bottom to form negative pressure , the effect of atmospheric pressure produces a downward suction on the waste chips, or a suction device is added from below to directly suck up the waste, as shown in Figure 7. From the production conditions, the amount of punching oil can be adjusted, and the punching SPM can be adjusted. In short, it is possible to fundamentally distinguish problems and think in multiple dimensions, and the ideas and methods of mold maintenance are ever-changing.

New application and progress of precision high-speed stamping technology

With the iteration of scientific and technological innovation, precision stamping continues to expand the scope of application with its unique advantages such as high efficiency and repeatability, especially in terms of product function expansion, such as the shear surface as the functional area of ​​the product, which will inevitably affect the shear surface. There are very high requirements for quality, and the needs of bright and flat, no burr, no stamping sag, full bright belt, etc. continue to expand the ideas of precision stamping designers. In terms of processing methods, in the processing of some products, precision stamping has successfully completed the process that could only be completed by die-casting Cnc, lathes, etc., thereby greatly improving production efficiency and reducing production costs. In terms of process technology, the precision stamping process combined with automation technology, the precision stamping process combined with photoelectric technology, the non-waste stamping process, the low-stroke ultra-high-speed stamping process, and the multi-material belt mold design process have gradually been adopted by the precision high-speed stamping industry. Use, technical capabilities are also constantly innovating.

As a practitioner of precision high-speed stamping, maintain a dedication to technology and the original intention of continuous pursuit from preliminary analysis, mold design, production and maintenance to technological innovation and application, and continue to explore and excavate with the attitude of excellence. my country’s precision high-speed stamping It is just around the corner for technology to ride on the east wind of “Made in China 2025” and stand on the top of the world industry.

 

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