With the increasingly fierce competition in the automobile industry, the model renewal is getting faster and faster, and the cycle is getting shorter and shorter. The mold development department needs to summarize and analyze each link of the mold development, shorten the development cycle, in order to achieve the purpose of improving the mold development efficiency.
The development of mould for automobile cover parts is divided into two stages: design and manufacture. Design includes stamping SE, stamping process DL figure design, CAE analysis and die surface compensation design, CAM mold design, mold structure design, FMC, structure and surface programming, manufacturing including FMC production, casting billet preparation, once at the beginning of the processing, assembly and secondary processing, assembling, bedding-in, debugging and improving quality and delivery process. In the mold development cycle, the mold design cycle of the vehicle is usually about 4 ~ 5 months, while the mold manufacturing cycle is as long as 12 months. Debugging and quality improvement account for 5 ~ 6.5 months. Therefore, improving the manufacturing efficiency of the mold is of great significance for shortening the development cycle.
Present situation of mould design and manufacture of covering parts
In recent years, the development of covering mold has made great progress in technology. Most of them have realized 3D DL design, CAE analysis of the whole process, compensation design of die surface and unequal clearance design of die surface. The 3D solid design of the mold structure, dynamic interference simulation, waste slip simulation and stamping automatic line simulation, etc.
In the mold manufacturing, FMC three-dimensional processing has been implemented, the primary processing is fully programmed, the secondary processing is automated, the mold quenching (the implementation of medium frequency quenching and flame quenching),Progressive Die Stamping, some enterprises have carried out laser quenching, the implementation of fire surface finishing processing. Mold manufacturing has carried out the “one flow” manufacturing mode.
The main reasons for the long mold manufacturing cycle include: the clamping difficulty of some parts, the inappropriate gap between convex and concave dies, the heavy workload of research and preparation, the defects such as cracking, wrinkling and springback of some parts that need repeated debugging and rectification, the improper planning management and design errors.
Process and die surface design issues
1 product technology is not reasonable, it is difficult to completely solve from the stamping process, parts can not meet the quality requirements, debugging is difficult, resulting in mold change or repeated debugging.
2. The CAE analysis parameters are not set reasonably or the performance of materials selected for analysis is better than that actually used in production, and the analysis does not consider the safety margin or the special requirements of products, resulting in a large deviation between process design data and manufacturing debugging results, resulting in repeated debugging.
3. There are defects in process data or parts product data, which should be solved in the later debugging.
4. The design of die surface clearance is not reasonable, resulting in a large amount of work in the later stage of research and matching. The design does not consider the thickness change of materials in the forming process of parts, the concave core compensation of machine tools, and the expansion treatment of parts. The UNCOLORED PART OF THE top drawing DIE is designed according to the material thickness gap, resulting in the excess of the shaped surface of the colored part needs to be fully researched and matched, wasting more than 30 hours.
5. The angle of edge trimming is not reasonable, or it is easy to produce burrs at the cutting edge of the side trimming, which often causes repeated debugging. Trimming edge expansion accuracy is not enough or test material verification is not allowed, resulting in edge adjustment and repair welding processing, especially sometimes the modified edge is not vertical, not sharp and uneven gap, burr, need to be adjusted many times.
6. Root-clearing design of non-important fillet when establishing standard die surface design.
7. Timely and accurate transmission of design information is an essential part of decreasing repetition. In order to assure the smooth flow of information, specifications and information sheets should be established, such as data handover sheets, color cards, quenching area indication charts for turning over types of molds, etc., which should be placed in PDM and ERP.
Mold structure design and manufacturing process optimization
1. Exhaust holes and bolt holes. Die exhaust hole and bolt hole design, in CNC milling out, or vertical hole point nest, lateral in CNC milling out, vertical hole fitter drilling, shorten drilling time, enhance accuracy.
2. Te establishment of special-shaped punch, wedge and slider parts clamping support system specifications, design reserved process chuck, can achieve the unity of programming and processing, enhance processing efficiency and accuracy. An example of the use of the design slider chuck and clamp is illustrated in Figure 9.
3. Mold identification. According to the characteristics of each user and the mold factory, the mold identification standard is established, and the logo or the printing position of the logo is designed on the mold holder and the block, and the casting is given priority to the casting. The operator can locate or install the logo according to the logo, and the mold maintenance is useful. FIG. 10 shows an example of marking the slider and mounting surface of the repair die.
4. Study the processing parameters of the number milling surface that affect the accuracy and efficiency, and set optimization specifications for tool speed, feed, step distance, cutting mode and allowance combined with the characteristics of each part. For example, the finishing allowance of the die surface is modified to 0.05mm, the tool speed and feed are adjusted, the semi-finishing and finishing efficiency of the die surface is enhanced by more than 40%, and the roughness and accuracy of the die surface are likewise considerably enhanced.
5. Adapt the processing route of trimming and turning over pieces. Trimming and spinning the piecing surface and edge are processed in place step by step, and then assembled after heat treatment. For trimming the edge of the die, the allowance for finishing is only left after fire. From the programming, it is executed independently, saving the cycle of processing and heat treatment of the piecing surface and edge.
With the improvement of the mould database covering parts and in-depth analysis software applications, as well as improve the machining accuracy of machine tool, as long as each design refinement technology stage, considering the problems at the design stage, from product design, process design and die design source, to fully virtual verification, analyzing the problem that happened before, or find the defects of prevention, Take measures as soon as possible, information transfer in place, can reduce the assembly, processing clamping and auxiliary time, improve the manufacturing accuracy, will greatly reduce the research and debugging time, meet the quality requirements of stamping parts, and eventually achieve the purpose of shortening the mold manufacturing cycle.