Establishment of CAD knowledge base of the hottest

The establishment of intelligent pass CAD knowledge base

Abstract This paper analyzes the necessity of applying expert system technology to pass design CAD, and according to the characteristics of angle steel pass design, puts forward the method of establishing angle steel pass design knowledge base, and applies it in pass design CAD

keyword expert system pass design CAD

1 preface

with the increasing popularity of computers, the research of computer-aided pass design is more and more in-depth, and the level of pass CAD is also constantly improving [1]. Generally, the pass design CAD system only completes the pass design calculation and drawing of engineering drawings, but there is another very important aspect of pass design, namely conceptual design, including the preliminary selection of overall performance parameters and overall structural scheme and scheme decision-making, which needs to be completed by using the empirical knowledge and heuristic knowledge of experts, so it also involves the technology of expert system. Expert system is a branch of artificial intelligence. Combining artificial intelligence technology with CAD technology to form intelligent CAD is a direction of CAD development

intelligent CAD is to solve the design problems of engineering or products in a specific field according to some knowledge or rules. This CAD technology based on knowledge base and rule base connects the connotation of design with the expression of design, and guides users to make choices and decisions about the design process and expression form. Its basic components are user interface, knowledge base, reasoning mechanism, engineering database, etc., and then form a decision support system. An important feature of intelligent CAD is that the system has a knowledge base containing a large amount of knowledge in a specific field. Therefore, an important work of establishing pass intelligent CAD is to collect and sort out the knowledge in the field of pass design CAD and form a knowledge base. By analyzing the characteristics of pass design of angle steel, this paper puts forward the method of establishing the knowledge base of pass design of angle steel

2 analysis of pass design knowledge base

the important feature of pass design is that it requires both empirical knowledge and a lot of design calculation. Design calculation inevitably involves calculation models and methods, which can be described by mathematical methods. The accuracy of mathematical model description and the choice of calculation method directly affect the quality of design results. In addition, the pass design also requires a lot of empirical data and methods, including a large number of expert knowledge in the field of pass design, which is difficult to be accurately described by mathematical models, especially in the determination of the overall scheme. Such as the selection of raw materials, the determination of raw material size, the determination of pass system, the arrangement of rack passes, the selection of pass basic empirical parameters, the determination of design method, the type of overall design scheme and the evaluation of design scheme, etc. these knowledge are very important for the determination of the overall scheme of pass design. Due to the improper selection of the overall design scheme, it is difficult to ensure the optimal result of the pass design even if the accurate mathematical model and the correct design and calculation method are adopted. The description of these knowledge can only use the expression technology of knowledge, so it is very necessary to use the function of expert system to summarize and sort out the knowledge of experts in these fields and form the knowledge base of CAD

the knowledge involved in pass design is very complex. From the pass used in the field practice, there will be different views on the same problem or due to different actual process equipment conditions, or different views and operating habits of designers. Some knowledge contains some kind of uncertainty. Many parameters and indicators are interrelated and affect each other. In actual determination, various factors should be comprehensively considered to select appropriate values. All these make the composition of knowledge base more difficult. But on the whole, after long-term practice, most experts have the same understanding, which can also be seen from the analysis of a large number of actual pass design results. Therefore, when constructing the knowledge base, it should be based on the general rules, and there is no need to adhere to some local experience. For some problems, when the process and equipment conditions are the same, there will be different design schemes, such as rack pass arrangement, determination of pass system, etc. for these problems, we should also analyze the advantages and disadvantages from the calculation results of multiple indicators through a lot of analysis and calculation, and conduct a comprehensive evaluation in combination with the actual production situation

in a word, the collation and induction of pass design knowledge is complex. Extensive research and continuous consultation of experts should be carried out in order to continuously improve the knowledge base

3 collation and induction of pass design knowledge

pass design CAD knowledge includes declarative and procedural knowledge. Declarative knowledge is more involved in the determination of the overall plan. The constructed knowledge base is mainly used to solve the following problems

1) selection of raw materials and determination of raw material size

2) total rolling passes and pass arrangement of each rack

3) selection of pass system (including finished hole, butterfly hole, slit hole and extension hole)

4) determination of basic empirical parameters of pass formation

5) selection of design methods and other important empirical data

to solve the above problems, it is necessary to analyze and summarize the results of on-site pass design, application occasions and on-site process equipment. Firstly, according to the practice of angle steel production, the layout of rolling mill is summarized into seven types, such as three in one row, four in three rows, tracking, continuous rolling, etc. The layout of the rack has a very close impact on the determination of raw material size, the arrangement of rack passes, the selection of pass system, especially the determination of extended pass system. Taking the seven types of rolling mill layout as the basic conditions, the above problem is divided into several sub problems. The expression and processing of knowledge is relatively convenient, which is conducive to the establishment of knowledge base. Now take the rack pass arrangement and pass system selection as examples for analysis

3.1 pass arrangement of each stand

the layout of the rolling mill, the cross-section shape and size of raw materials, and the total number of passes have an impact on the pass arrangement of the stand. Generally, only one finished product pass is arranged for the finished product rack, which is conducive to the adjustment of the rolling mill and the improvement of the finished product quality. The pass arrangement of other racks varies according to specific conditions. The following issues are mainly considered when determining the pass arrangement of the rack

3.1.1 layout of rolling mills

according to the analysis of the layout of rolling mills in the actual angle steel production workshop, the basic layout of rolling mills is divided into 7 types. For example, three in one row, four in three row, five in three row, tracking, and continuous rolling. In addition to continuous rolling and tracking, other types of mills usually use three high mills, and the rolled pieces are cross rolled on the upper and lower rolling lines. Among the seven basic types, the tracking type has the most changes, such as the number of rolling mills, the number of rolling passes of the first roughing mill, etc. the detailed division of this type is difficult to cover everything. There are many racks in the tracking layout, and most of them adopt single pass rolling, mainly to make the speed distribution of racks more reasonable. If the racks in a single pass are distinguished, the layout types of the remaining racks can be classified. Here, we should also pay attention to the parity of the number of remaining rack channels

3.1.2 total pass times of rolling

total pass times of rolling are determined by raw materials, finished products and average elongation coefficient. However, due to the different arrangement of rolling mills, there will be different requirements for the total number of passes. The total number of passes will be adjusted according to the different requirements for the average extension of large and small angle steels. The average elongation coefficient of large-sized angle steel is small, and the total number of passes can be increased when the above conditions are not met, while the small-sized angle steel is on the contrary

3.1.3 number of special-shaped holes

special-shaped holes of angle steel mainly refer to finished holes, dished holes and slit holes. The number of finished holes is determined, but the number of butterfly holes and slitting holes varies with the deformation properties of finished angle steel and metal. With the different sizes of angle steel, the number of butterfly holes can be increased from 2 to more than 5, and the number of slitting holes can also be 1 or 2. Sometimes there are vertical pressing holes in front of the slitting holes. This form is usually used for small angle steel or rolling mills with vertical rollers. Considering the size of rolled angle steel, the number of special-shaped holes can be determined

3.1.4 type of extension hole

angle steel extension hole mainly refers to box hole type. There should be at least one extension hole in the whole rolling pass, and in most cases there are more than three extension holes. The hole patterns used in practice are analyzed. In order to facilitate the establishment of knowledge base, the types of box extended holes are divided into 9 categories. Such as horizontal horizontal vertical (square), horizontal horizontal vertical (rectangular), etc. These categories of the extended pass are closely related not only to the arrangement of the rolling mill, but also to the setting position of the steel turnover device. Therefore, the seven layout modes of the rack are also ● bond laminates, a subsidiary of Lansheng in brilon, Germany, has expanded the production capacity of its continuous fiber reinforced thermoplastic composites, which can be further divided into several sub types according to the setting of the steel turning device. The clearer the decomposition of basic conditions, the more conducive it is to solve the problem of pass arrangement. For example, the raw material is square billet, the first roughing mill is a three high mill, and the rear of the mill is a lifting table without a steel turnover device. Vertical rolling is required before entering the slitting hole. If the extension pass is 4, it is difficult to meet the rolling requirements. According to the type of extension hole, one extension pass should be increased or reduced, and 3 passes should be arranged on the first roughing mill, or another 2 passes should be arranged on the second rolling mill. If vertical rolling is not required before entering the slitting hole, 3 or 5 passes can be arranged on the first roughing mill

based on the above problems, the pass arrangement of each rack can be determined according to the total pass number, mill layout and pass system. After the rack pass arrangement is determined, the gap time of each pass can also be determined according to the database. It is very important to calculate the hourly output of the mill and check the motor in the optimization design, for example:

1) the layout of the mill is the second type, the total pass number is 10, and the number of special-shaped holes is 5. Then the general arrangement of each erection is 5-3-1-1

2) the layout of the rolling mill is the fifth type, the total number of passes is 15, and the number of special-shaped holes is 5. Then the general arrangement of each track is 7-5-1-1-1

see Figure 1 for the structure of the rack pass arrangement knowledge base

3.2 determination of pass system

selecting pass system is the most important basic work in pass design. The main problem involved here is the type and number of special-shaped holes; Type of extension hole and pressing method of rolled piece

finished product holes are divided into open and closed holes. The number of butterfly holes and slitting holes varies with rolling conditions, and there are several different types of slitting holes. The arrangement of rolling and screwdown procedures of box shaped extension holes is similar. Here, attention should be paid to the number and position of steel turnover. The relationship between the type of extension holes and the layout of rolling mills is closer than that of special-shaped holes. The following problems are mainly considered in determining the pass system

3.2.1 section shape of raw materials

the section of raw materials generally includes square billet and rectangular billet. In most cases, square billet is used, and sometimes rectangular billet is also used in order to reduce passes. The change of the blank form will affect the rolling method of the rolled piece in the extension hole. When rectangular billets are used, the first pass is usually vertical rolling. In order to ensure the size requirements of rolled pieces before entering the slitting hole (vertical rolling is best before the slitting hole of small and medium-sized angle steel to ensure the width of rolled pieces entering the slitting hole. When the number of angle steel is large, flat rolling can be used before the slitting hole), the number of extension holes and pressing method should be adapted to it, and here