Characteristic matrix and group similarity coeffic

Machine tool characteristic matrix and group similarity coefficient

Abstract: Based on the jlbm-1 part classification and coding system, the characteristic matrix of machine tool is established, and the similarity coefficient of machine tool is defined in a new form based on part coding and machine tool characteristic matrix, so that the calculation of machine tool similarity coefficient can be directly completed by computer according to the characteristic matrix and part coding of machine tool in enterprise, It is conducive to the automation of machine tool similarity coefficient calculation and machine tool grouping

Keywords: classification; code; Group technology; Similarity coefficient; Automation

1 preface

among the many methods of dividing parts group and machine tool group into group units, the similarity coefficient method is a relatively simple and widely used one. The similarity coefficient method is a method that first calculates the similarity coefficient to measure a certain statistic, and then combines other methods to obtain the parts group and machine tool group of group units. Usually, the calculation of similarity coefficient can only be done manually, which requires a lot of statistical work of machine tools and parts, and a lot of calculation time. For example, the equipment is grouped by calculating the similarity coefficient between equipment. When the number of equipment and parts to be analyzed is hundreds or thousands, the amount of calculation is so large that it is difficult for people to accept this method in practical work. The method studied in this paper not only saves the usual necessary statistical work of machine tools and parts, but also realizes the automation of similarity coefficient calculation. It also enables the method of establishing group units by first using the similarity coefficient of machine tools to form group unit machine tool groups, and then forming group unit part groups by machine tool groups

2jlbm-1 parts classification and coding system

enterprises can use jlbm-1 parts classification and coding system as their own classification and coding system when applying group technology. The first and second code points of the jlbm-1 system are interrelated, which are the name category code of parts, the first code point is the coarse classification of part name category, and the second code point is the fine classification of part name category. The third to ninth code points are independent of each other. They are the shape and processing code of the part, and they are also independent of each other. They encode the material, the original shape of the blank, heat treatment, main dimensions, accuracy, etc. respectively. Each code point has 10 code values from 0 to 9

3 establishment of machine tool characteristic matrix based on part code

3.1 basis for establishing machine tool characteristic matrix

the shape of parts and the part characteristic items corresponding to each code point of processing code part are all processed by machine tools. The function of a machine tool is only to complete the processing of one or some part characteristic items corresponding to the code position of the shape and processing code part. From the perspective of machine tool application, the characteristics of the machine tool are not reflected in the structure of the machine tool itself, but in the function of the machine tool, that is, in what kind of materials, the original shape of the blank, the size range and accuracy requirements, the machine tool can complete the processing of which kinds of parts and which characteristic items. If the types of parts that can be processed by the machine tool, the types of materials that can be adapted, the original shape of the blank, the main dimensions of the parts, the accuracy that can be achieved, and the shape characteristics of the parts that can be processed can be expressed, the characteristics of the machine tool will also be expressed

3.2 establishment of machine tool characteristic matrix

in order to correspond to the part coding, enterprises establish the characteristic matrix of machine tools based on the jlbm-1 part classification and coding system. The lightweight development oriented by the utilization of new materials will undoubtedly face the major problem of material connection to express the characteristics of machine tools

generally, rotating parts and non rotating parts are processed in different group units. Before grouping machine tools, machine tools can be divided into two categories: machine tools for processing rotating parts and machine tools for processing non rotating parts according to the parts categories processed by machine tools in the enterprise (taking the first and second code points of jlbm-1 system as feature code points and classifying parts with coding classification method). The machine tool characteristic matrix established to obtain the machine tool group of group units can be established on the basis of the machine tool category

a matrix A10 is used for the characteristics of the machine tool × 13 means that the row number of the matrix corresponds to the code value of each code point of the jlbm-1 system, and the column of the matrix corresponds to the third to fifth code points of the jlbm-1 system. When determining the values of the column elements of the matrix corresponding to the third to ninth code points, the characteristic matrix of the machine tool processing rotating parts and the machine tool processing non rotating parts uses the "classification table of rotating parts" and "classification table of non rotating parts" respectively. Code point I (3 ≤ I ≤ 15) and code value of the part shape characteristic item that can be processed by the machine tool α I find the columns and rows corresponding to the characteristic matrix (note that the row numbers are 1 ~ 10, the code values are 0 ~ 9, and the code values α I corresponding to matrix α I+1 row, code point I corresponds to element a at the intersection of column I-2 of the matrix)[ α I+1][i-2], so that the value of this element is equal to α i。 In the eighth column of the characteristic matrix, find the elements on the corresponding row according to the code value of the tenth code point in the jlbm-1 system according to the material type that the machine tool can adapt to, so that the values of these elements are equal to the code value respectively. The values of the elements in the ninth, eleventh, twelfth and thirteenth columns of the matrix are taken from the values of Wang Liping, deputy general manager of Tongling jingsai Electronics Co., Ltd., said that the method is the same as that in the eighth column. The tenth column of the matrix corresponds to the twelfth code point (heat treatment) of the jlbm-1 system. The heat treatment is independent of the machine tool of the group unit. It can be assumed that the machine tool can complete the heat treatment function corresponding to each code value of the twelve code points, and the values of the elements in each row of the characteristic matrix column corresponding to this code point range from 0 to 9. This assumption is necessary for the later practice of judging whether the parts match the machine tool according to the part code and the machine tool characteristic matrix. For those elements in the characteristic matrix that do not get the value according to the above method, the values of other elements are all taken as 0, except for the values of eight, nine, eleven, twelve, thirteen and other column elements in the first row, which are taken as 1 (the code value 0 of ten, eleven, thirteen, fourteen, fifteen code points in the jlbm-1 system has different meanings from the code value 0 of three to nine code points). In the first to seventh columns of the matrix, 0 represents the shape characteristics of the parts that cannot be processed by the machine tool, or the parts of the enterprise have no characteristic items in the corresponding code points and need to be processed by the machine tool

the application of the same machine tool in different enterprises may be different, and the characteristic matrix of the same machine tool may also be different. The difference of the characteristic matrix of the same machine tool just reflects the different process uses of the same machine tool in different enterprises

the equipment characteristic matrix can be established during the general survey of all parts processed by the enterprise in order to establish the part coding system of the enterprise. It can also be directly based on the function of the machine tool to clarify which part shape characteristic items are used to complete the processing of each machine tool in the enterprise, which kinds of parts these shape characteristic items belong to, the types of materials that the machine tool can adapt to, and the original shape of the blank used, The characteristic matrix of each machine tool is established after the main size range of the parts that can be processed and the accuracy level that can be achieved. Obviously, the latter method does not need to survey the processing of parts

for example, in an enterprise, a machine tool is used to complete the processing of characteristic items such as "one-way step" (the third code point, code value 1), "two-way step" (the third code point, code value 2) and "thread" (the fourth code point, code value 2) outside rotating parts. The materials that the machine tool can adapt to include gray cast iron, special cast iron, ordinary carbon steel and high-quality carbon steel (the tenth code point, code values are 0, 1, 2 and 3 respectively), and the original shapes of blanks include bars, castings Forgings, etc. (the eleventh code point, code values are 0, 5 and 6 respectively), the diameter range of parts that can be processed by the machine tool is 100 ~ 400 (thirteen code points, code values 4, 5, 6 and 7), the length range is 200 ~ 1000 (fourteen code points, code values 2, 3, 4, 5 and 7), and the accuracy grade is high-precision "outer revolving surface processing" (fifteen code points, code value 4). The characteristic matrix of the machine tool is as follows:

4 judgment of part matching with the machine tool

after establishing the characteristic matrix of the machine tool, you can directly judge whether the part is processed by a machine tool from the part code (that is, whether the part is matched with the machine tool)

suppose the code of a part a is:

a1a2a3a4a5a6a7a8a9a10a11a12a13a14a15

the characteristic matrix of machine tool a for processing such a part is a10 × 13. AIJ is the element of the matrix. The following steps can be used to judge whether part a is processed by machine tool a:

(1) auxiliary code matching. The auxiliary code of the part is the tenth to fifteenth code point, and the eighth to thirteenth columns of the characteristic matrix correspond to the auxiliary code. The auxiliary code must match the eighth to thirteenth columns of the characteristic matrix completely before the machine tool can process the part. The criteria for auxiliary code matching are:

α i=akj 10≤i≤15,j=i-2,k= α I+1

(2) shape and processing code matching. As long as one of the shape characteristic items of a part is processed on a machine tool, it belongs to the part processed by the machine tool. The three to nine code points of the part are the shape and processing code. The one to seven columns of the matrix represent the characteristic items of the part that can be processed by the equipment. The matching criteria between the shape and processing code of the part and the characteristic matrix are:

α I=akj ≠ 0 "Kim Choate, the marketing director of the company, wrote on their website that 3 ≤ I ≤ 9, K= α It is true at least once under the condition of i+1 and j=i-2

if the above two conditions are met, we will say that part a matches machine tool a

5 machine tool similarity coefficient based on machine tool feature matrix and part code

considering the requirements of product characteristics, utilization and durability, the similarity coefficient proposed by Jaccard to form a group unit machine tool group is defined according to the similarity of the two machine tools to the processed parts. The expression of the similarity coefficient is:

where SIJ - the similarity coefficient of machine tools I and j

n - the total number of parts analyzed

calculating the similarity coefficient between each two machine tools requires examining the processing of all rotating or non rotating parts of the enterprise on these two machine tools, and the workload is quite large. After the machine tools are divided into two categories: processing rotating parts and processing non rotating parts, using this similarity coefficient to form a group of machine tools, it is necessary to calculate the similarity coefficient between the machine tools in the two categories. The workload is larger, the calculation is particularly complex, and it is not convenient to use a computer to process

after establishing the characteristic matrix of the machine tool, the part code can directly determine whether the part is processed by the machine tool (that is, whether the part matches the machine tool). Accordingly, the similarity coefficient represented by equation (1) can be redefined based on the part code and the machine tool feature matrix. The redefined similarity coefficient is shown in formula (2)

in the formula, SAB -- the similarity coefficient between machine tool a and B

n -- the number of parts in the part category

the value of formula (2) is exactly the same as that of formula (1). Although the manual calculation of equation (2) is as troublesome as equation (1), it is convenient to use the computer to calculate the machine similarity coefficient directly from the part code and the machine tool characteristic matrix. The work that the computer needs to do is only to compare the part code with the machine tool characteristic matrix and count the comparison results. The statistical work and cumbersome calculation of machine tools and parts that usually have to be completed manually are omitted. The similarity coefficient defined in the form of formula (2) makes it easy to automate the method of establishing machine groups of grouped units through machine tool similarity coefficient, and then establishing part groups of grouped units

6 conclusion

(1) the characteristics of the machine tool are not expressed in the structure of the machine tool, but in what kind of materials, the original shape of the blank, the size range and the accuracy requirements, which kinds of parts and which characteristic items can be processed by the machine tool. The machine tool feature matrix based on jlbm-1 part classification and coding system accurately represents the characteristics of the machine tool

(2) the similarity coefficient defined in a new form based on the part code and the machine tool feature matrix is convenient for