Key technology and management of the most popular

2022-08-23
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The key technology and management of large-scale mold production

mold is different from general manufacturing products. Its biggest feature is single piece order production. Each set of mold is a new product development process from design to manufacturing, and there is basically no repeated manufacturing of identical molds. Therefore, many people believe that due to these uncontrollable characteristics of molds, the scale of mold manufacturers cannot be large, and the production capacity cannot be too full. However, with the application of some advanced technologies in the mold field, the mold development process has undergone fundamental changes, especially the technological progress has promoted the progress of mold production management, making large-scale mold production possible

large scale mold production has several characteristics: large output value; There are many customers, many projects and miscellaneous standards; Many enterprises participate in production cooperation. The general process of stamping die development is: stamping process design - die structure design - foam mold production - casting and standard parts procurement - machining - die assembly - die debugging. This paper mainly discusses the key technology and management of supporting large-scale die production from the main links of automobile stamping die production

stamping process knowledge base and intelligent process design

1. Stamping process knowledge base

stamping process is the core content of stamping die technology, and the quality and cycle of parts are directly affected by the stamping process. For a long time, the stamping process depends on experience. Therefore, even the same part will have different process schemes in the eyes of different people, and it is often not good to evaluate the advantages and disadvantages in the design stage, and there is no comparability when debugging. On the one hand, this phenomenon shows that the process plan is not unique, only better; On the other hand, it shows that this content lacks controllable standards and the quality is not guaranteed. How to realize the control and standardization of stamping process is the most important in stamping die technology. To realize large-scale production, we must first solve this problem

for the stamping die of automobile panel, there are about 300 ~ 400 stamping parts in a vehicle model, and there are about dozens of kinds of stamping parts classified according to the characteristics of the parts. Generally, there are only a few difficult points or feature points that can affect the process in each part. Therefore, a knowledge base can be established according to such feature classification, and an intelligent stamping process analysis system based on knowledge engineering can be developed by applying KBE technology and manual interaction function, Rely on software technology to ensure optimized and standard process results. The application of this technology can break the barriers of experience, so that people with a little knowledge of stamping can complete these tasks. Figure 1 shows the interface of stamping process knowledge base template

Figure 1 stamping process knowledge base template

it is worth mentioning that the impact on stamping process analysis is not only process experience, but also the design of body parts themselves. A good product design should not only meet the requirements of function and beauty, but also consider the manufacturing process and cost of the product. Automobile companies with strong strength generally have their own body stamping process department, whose role is to analyze the manufacturing process of products in the body design stage and provide suggestions for improvement. If it is a deformed car design, it will also feed back some previous problems to this change. The difficulty of developing such body mold is also greatly reduced. In contrast, the stamping process problems left over in the design of some domestic automobile bodies are large. Once the digital model is sealed, the change process is complex and difficult, which will not only affect the development cycle, but also leave quality hidden dangers. Therefore, in the development of modern body mold, the stamping process analysis in the body design stage is becoming more and more important, and it is also an important link to control the mold development. As the front-end technology of mold development, stamping technology should be gradually integrated into the process of automobile body design. This demand will promote the strategic alliance between mold enterprises, automobile companies and design companies

2. Analysis of stamping CAE aided process

the application of CAE Technology in the field of stamping die is a major technological revolution in the die industry. The current stamping CAE software is basically developed based on the finite element theory. The more popular software in the world are AutoForm, DYNAFORM and PAM-STAMP. With the popularization of CAE software in the mold industry, the function of the software is also constantly improved and strengthened. The current software can complete the simulation calculation and analysis of the whole process of stretching, trimming, flanging, shaping and springback (see Figure 2)

Figure 2 Calculation and analysis results of springback

the application effect of stamping CAE technology should give full play to its several functions:

(1) establish a stamping process evaluation standard system based on CAE analysis results, which becomes the basis of controlling the process

(2) integrate stamping process experience, combine CAE analysis with knowledge engineering, and become a tool to optimize stamping process

(3) provide reference basis for auxiliary commissioning in combination with the actual measurement of stamping commissioning

(4) the process control based on CAE analysis should have sufficient margin to improve the applicability to the actual stamping conditions

standardized and templated rapid die structure design

with the development of CAD software technology, parametric 3D design has been widely used in the die field. At present, the 3D CAD software used in the stamping die field includes CATIA, UG and Pro-E, which have strong parametric functions. It is an important condition to meet the requirements of large-scale mold production, improve the speed of mold structure design and shorten the design cycle. Relying on parametric design software, studying the structural characteristics of various stamping dies and developing template design system can reduce repeated structural design and significantly improve the design speed. However, due to the singularity of mold structure design, it is not feasible to pursue a universal templating system, but the mold design process can be turned into a cumulative process of local parametric structure by using the associated standardized parameterized local typical structure, which can be realized by software Boolean operation. The mold templating design system is shown in Figure 3

Figure 3 mold templating design system

mold structure design is the specific realization of the process. In the traditional mold design process, the mold structure design of each sequence of the same part is completed by different people, and there is little communication between them. If there is an unclear design change of the previous process, the information cannot be transmitted in time, and the mold structure change is often affected by process changes in production, As a result, the next process actually wastes a lot of time doing useless work. For a certain process, the processes are interrelated. If the links between processes can also be connected in the mold structure of each sequence, the parallel of each sequence in mold design can be realized. The key technology to realize concurrent design is associative design. Now some software module systems based on knowledge engineering can help realize associative design. Through associative design, it can also realize the repeated application of mold design resources of similar parts and shorten the design cycle

Another difficult problem in mold design is to make the pointer return to zero and change large quality control. Simply from the perspective of mold development, there is basically no possibility to improve the existing mold. Then we should go through the process of "mold design - physical verification - modified design - formal manufacturing" and the demand for electrical insulation and flame retardant materials in the power and electrical industry to ensure the quality of products. However, due to the problem of cycle and cost, "physical verification" and "formal manufacturing" are often combined into one link, so there will be various "anomalies" in actual production, These "anomalies" affect the product quality and cycle, and even disrupt the whole production plan. The root of the problem lies in the lack of verification process. Applying advanced digital means, we can realize "Digital Verification" instead of "physical verification". The specific methods are:

(1) establish standard design methods to avoid abnormal problems caused by irregular personal design habits

(2) establish a strict quality control process and check the proofreading

(3) use advanced digital software technology for targeted verification, such as developing CAD software function modules for automatic interference inspection; Using finite element software to analyze the structural strength; The castability of castings was analyzed by flow casting analysis software; The dynamic motion analysis of die and stamping line is carried out by using the mechanism motion simulation software; Using tool motion simulation software for Machinability analysis. Figure 4 shows the simulation results of mold casting process

Figure 4 mold casting process simulation

"Digital Verification" can replace "physical verification" to achieve quality control, but if each set of mold goes through such a process, it will take a lot of time. Therefore, relying on digital simulation calculation to establish various design standards and realizing the control of various quality parameters through the proofreading and inspection function of software is the most effective method

high speed and high precision NC machining

High Performance NC milling technology has become one of the core technologies of high-quality automobile mold manufacturing because of its excellent match between high machining accuracy and high cutting feed speed. High Performance NC machining of mold free-form surface can greatly improve mold machining accuracy and shorten machining time, so as to improve mold manufacturing quality and production efficiency

tool path design and planning is the primary task of high-performance NC machining of free-form surfaces. The traditional tool path design planning is based on the geometric characteristics of the machined parts. According to the experience, the tool path is designed and the cutting parameters are set, and then it is transformed into NC machining code, which is realized by NC equipment. In order to realize high-speed and high-precision NC machining of such tool path, the NC system needs to have very good advanced functions such as program preprocessing and monitoring. These functions can scan the NC code to be machined while controlling the machining, and adjust the feed speed accordingly according to its calculation method. Some CNC systems also have better intelligent error compensation and contour control functions for high-performance machining. These advanced hardware functions play a key role in ensuring the machining accuracy of parts

processing efficiency and reliability should also be considered in mold processing. The application of machining path optimization technology can improve the machining efficiency, but due to the design or casting errors, the machining entity may be inconsistent with the design size, resulting in the phenomenon of machining knife collision. Therefore, before machining, the solid castings should be tested and confirmed, and the machining process simulation should be carried out with simulation technology (see Figure 5), so as to ensure the reliability of machining and optimize the machining path

Figure 5 machining process simulation

High Performance NC milling and tool path optimization design solve the problem of single product mold manufacturing, but to ensure the manufacturing efficiency of a large number of molds, it requires a reasonable matching of the capabilities of various processing equipment. According to the processing characteristics, the mold structure can be divided into mold body, punch and concave mold, trimming insert, integer insert and other types. Organizing professional processing according to the type can significantly improve the efficiency. Since it is difficult to predict the volatility of mold orders and types, adopting appropriate specialized outsourcing processing is the most effective way to improve efficiency and control costs

digital mold debugging

mold debugging is an important link in the mold development process. Due to the lack of early "physical verification" process, the debugging stage also plays the task of finding design defects or mistakes and correcting them. Its completion quality and cycle mainly depend on three aspects: the quality of mold process and design

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