Views: 6 Author: Site Editor Publish Time: 2022-10-10 Origin: Site
Currently, the rapid design system for sheet metal dies is the main system in the production of sheet metal parts processing. In this regard, this paper discusses the concept of sheet metal die rapid design system, outlines the design of standard die base library, rapid design of concave and convex dies and the design of standard die holder, and aims to provide valuable reference opinions for major industrial production-oriented enterprises.
Sheet metal parts are widely used in the production process of large machinery and equipment because of their advantageous features such as high strength, good quality and low cost. However, as the appearance shape of sheet metal parts is becoming more and more irregular and complex, higher requirements are put forward for the production efficiency and processing quality of sheet metal parts. In the whole design and production cycle of a large machinery and equipment, the design of sheet metal tooling determines the design quality and production of the whole product.
efficiency. In order to effectively solve all kinds of diverse technical problems in sheet metal mold design and processing, more and more mechanical design engineers have gradually increased the importance and investment in sheet metal mold design.
Currently, sheet metal parts are widely used in large automobile manufacturing processes. Not only does it take up more than half of the total working hours, but the quality of sheet metal parts design and production also largely determines the final results of the whole automobile manufacturing process. In the manufacturing process of large automobiles, due to the large volume and complex appearance of sheet metal parts, the design of sheet metal dies is also relatively difficult and the production cycle is relatively long.
Generally speaking, the traditional sheet metal mold design lacks the support and assistance of a mold base library. As a result, the accumulated practical design experience, mechanical process principles and processing and manufacturing rules are not deeply integrated into the mold design process, which leads to a series of problems such as unreasonable design, low design efficiency and substandard design quality of mold tooling. In the process of sheet metal mold design, due to the similarity of most common parts
Therefore, under the premise of different sizes of common parts, how to improve the quality and production efficiency of such parts has become a new topic for mechanical engineers to explore. Since the application frequency of such parts in the whole sheet metal mold design process is high, it is especially important to design a set of complete, expandable and standardized mold library. The design and use of the mold library greatly improves the efficiency of mold design, shortens the mold design cycle, and improves the level of mold design quality, which has a high value of promotion and application.
The design of convex and concave dies is an important part of the design and processing of sheet metal parts. The design quality of the convex and concave dies determines the design quality and processing accuracy of the whole sheet metal parts. The traditional design of convex and concave dies often refers to the accumulated practical design experience and combines the key process parameters of the sheet metal die to make a reasonable design of the rough die in advance. According to the initial design drawing, the rough billet sample is processed and the surface structure of the convex die and concave die is modified according to the appearance of the rough billet sample. After determining the shape of the surface structure, the design accuracy of the surface structure of the convex die and concave die is further improved by repeated debugging and adjustment. However, this traditional design mode also has significant defects. The mechanical design engineers have limited design specifications to refer to, and the design is carried out entirely based on personal practical experience, which often requires a lot of time, low design efficiency and long design cycle.
The convex and concave die design model discussed in this paper fully considers the basic features and fundamental knowledge of the designed finished product, and builds a rapid design model with structural morphology characterization and knowledge information parameterization. This design model is driven by dimensional specifications, and brings together the conventional and specific features of sheet metal to create a complete and accurate model to digitally quantify the sheet metal features for describing the functional relationships of sheet metal variables. The result is a digitally quantized sheet metal design. These various design features are based on the rich practical experience in sheet metal design and processing accumulated in the past, and have certain accuracy, reliability and practicality, which effectively make up for the design defects of traditional convex and concave dies. Specifically, the three key steps of digital modeling are described as follows.
① First, select appropriate features for description as input conditions for creating a digital model of feature parameters. Since mechanical design engineers need certain input conditions and criteria when creating feature descriptions, feature descriptions are particularly important for feature orientation. Feature description is the process of integrating and digitally quantifying geometric element information with reference to relatively cluttered features. Typically, the digital quantitative representation consists of positioning elements such as center of gravity points, hole centerlines, outer contour lines, support surfaces, and profile positioning surfaces. As a result, the key design points of convex and concave dies can be further defined.
②The feature modeling is used as the basis for the surface modeling of convex and concave dies. Since the full constraint model cannot be changed after the digital quantitative description of the features, it is necessary to constrain the feature positioning information at the early stage of model creation, so as to provide reliable reference information for the subsequent optimized design and ensure that the overall design results meet the expected standard requirements.
③Establish the binding constraint relationship and determine the parameterization information. After the above two steps are completed, the variable analysis is performed on the key parameter information of all geometric shapes and the location information between each part to further clarify the variable analysis relationship and update the variable parameter information simultaneously. After creating the digital model to integrate and analyze the geometric element information, the digital model of convex and concave dies containing current values, variables and digital formulas is formed to ensure the uniformity, completeness and standardization of the digital design models of convex and concave dies.
The design of standard die holder is as important as the design of convex and concave dies. The standard die holder mainly includes a series of auxiliary tools such as guide pillars, die holders and positioning pins. According to the difference of the function of the die holder in the sheet metal die design, it can be further divided into auxiliary support type die holder, positioning guide type die holder, unloading transfer type die holder and fixed role type die holder. Among them, the positioning guiding type mold frame can be further divided into positioning pin guiding type mold frame and retaining pin guiding type mold frame.
The unloading transfer type die frame can be further divided into two categories: unloading plate transfer guide die frame and top plate transfer guide die frame.
According to the difference of the reference standard of the mold frame design, the mold frame design plan can be divided into two forms: standard mold frame design and non-standard mold frame design. The main function of the mold frame is to improve the design quality of sheet metal mold and increase the processing productivity of the mold. Extra emphasis should be placed on the fact that the mold design should be in the form of standard die set-up design as much as possible.
The creation of digital models is also an indispensable and critical part of the standard die design. According to the difference of modeling process and order, it can be further divided into two categories: top-down modeling form and bottom-up modeling form. The top-down modeling form refers to the formation of new parts through the second assembly adjustment of the already formed parts. The dimensional specifications of the newly formed parts are consistent with those of the original parts, thus, fundamentally solving the problem of assembly conflicts. Bottom-up modeling form is to create a model of each part in advance, and then loaded and assembled according to the pre-set order, forming a clear division of labor, coordinated with each other parts model. This kind of part model can optimize the design resource allocation, improve the modeling efficiency and quality, and avoid the assembly conflict problem effectively.
In this paper, the advantages and disadvantages of top-down modeling and bottom-up modeling are considered comprehensively and objectively, and the modeling process is divided into two key steps: part level and assembly level, taking into account the characteristics of the standard model. Among them, in the part-level modeling, the design process can be simplified by referring to the standardized digital model, avoiding a large number of repetitive designs and improving the efficiency of design. In the assembly level modeling process, we optimize the parameter information of parts and create a normalized table of assembly characteristics to realize the parametric design of digital model and improve the overall design quality.
In summary, in the sheet metal mold design process, there are a series of outstanding problems that need to be solved, such as poor design quality and low production efficiency. The application of the rapid design system for sheet metal moulds has realized the parametric modeling design of the standard database, convex and concave dies and die frames, and improved the overall design level, which can meet the basic needs of sheet metal moulds for large machinery and equipment manufacturing to the greatest extent.
