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Information Management of Equipment Productivity in Compliance with Digital Manufacturing Mode Li Wei, Chen Kun, School of Mechanical and Electronic Engineering, Central South University, P.R. China, 410075 Abstract The importance of equipment manufacturing ability in the digital enterprise is analyzed, and some problems on the management information of equipment manufacturing ability are pointed out. Then taking machine tool for instance, the description model of the management information of equipment manufacturing ability and the method of establishing corresponding database system are put forward. The study provides a practical guide for the digital description of equipment manufacturing ability in enterprises. Key words Digital enterprise, Equipment manufacturing ability, Management information , 1 Introduction Nowadays, the digital manufacturing has become a developing orientation in the modern enterprise because of the introduction of digital technology to the manufacturing technology. As a result, the manufacturing activities increasingly depend on equipments. Therefore, the description of management information of equipment manufacturing ability plays a key role in digital-based manufacturing. In recent years, compared with the product information, the study on description of equipment manufacturing ability information develops very slowly mostly because of the diversity and complexity of equipment and the dynamic change of its environment, thus blocking the practical development of equipment manufacturing ability information model to some extent. By far, there are a few scholars both at home and abroad who have studied the information description of equipment manufacturing ability. For example, Hu qingxi has investigated the facility resource model based on hierarchical and feature technology in concurrent environment[1], and a dynamic model of equipment resource for an integrated production environment was put out by Chen weike and Wubo[2], et al. Although these scholars have made some progress in modeling management information of equipment manufacturing ability, their studies don’t consider the details interrelated with the machining activities of equipment, such as the information of cutting depth and productivity computation, etc, which are important for the decision-making of many departments, such as process planning department and product manufacturing department. So in this paper, taking machine tool for instance, all information interrelated with the machining activities is abstracted from the complex information of equipment. Finally the description of management information model of equipment manufacturing ability and its database system are studied. 2 The basic demands for the management information of equipment manufacturing ability Different departments in an enterprise have different demands for the management information of equipment manufacturing ability. For example, the product design department need consider the producibility of product while designing, so some basic information of equipment manufacturing ability should be understood, such as the material and structure of parts that the equipment can deal with, as well as the accuracy that the equipment can arrive at. And the process planning department must know all information about the equipment manufacturing ability in detail in order to determine the process scheme of parts, such as information of cutting depth and man-hour, etc. However, in the traditional management information system of equipment manufacturing ability, the management information description model of equipment manufacturing ability is built only according to the different demands in the different departments. And as a result, the information databases established by different departments are various and independent from another. Such a kind of multilevel management may certainly cause some troubles as follows: 1) The redundance of datum due to the lack of the unified and intact definition and expression of 275 equipment manufacturing ability information; 2) The impossibility in exchanging information among different departments because of the difference of data expression; 3) The difficulty in maintaining and updating data owing to so many store locations of datum, and waste of store space. Under the digital manufacturing mode, the production task is usually finished by virtual enterprises, and the environment of equipment changes with the different tasks. Then various equipments must be rearranged quickly according to different task and their manufacturing abilities. Therefore it is essential to found unified, shared and flexible information database of equipment manufacturing ability. 3 The foundation of the management information model of equipment manufacturing ability According to the analysis above, the management information model of equipment manufacturing ability is built in feature-based modeling technology. The features of equipment manufacturing ability, which are the technical property relevant to the manufacturing ability, embody the comprehensive manufacturing ability of machine tool, cutting tool, clamp, measuring tool and machining environment, etc. They may be divided into three classes as rendered below. 3.1 The feature of management The feature of management is a combination of a group of information related to the management of equipment manufacturing ability, whose main contents are as follows: (1) The general information: It includes the name, type, number, specification, purchase date, price, workshop, section, cell, fare per hour, useable hour and current status of equipment, etc. (2 The information of the main components of equipment 1 The information of coordinate axis: It includes the amount of axes, the name and amount of linkage axis, the name, removable distance and rotation accuracy of principal axis, etc. 2 The information of worktable: It includes the name, function, size, maximal load and maximal removable distance of worktable. 3 The information of cutting tool storage: It includes the name, capacity, velocity, exchange mode and exchange velocity of storage. 4 The information of cutting tool shelf: It includes the name, amount, removable distance and turning angle of cutting tool shelf. 5 The information of numerical control system: It includes the type, supplier, CPU type, memory type, memory capacity, numerical control mode, NC code and NC rule. (3) The information of spare parts: It includes the name, type and amount of fittings, cutting tool, clamp, measuring tool of machine tool, etc. 3.2 The feature of function It embodies the manufacturing abilities that equipment possesses. Because most equipments not only have the commonness of function feature of the same kind, but also their own personality, the common and special features of equipment function are abstracted. 1 The common feature of function: Embodying the commonness of the same kind and reflecting the common manufacturing ability of equipment, it is easily classified and has good commonality and wide application. As a result, it can be described with fixed parameters and users may input some datum according to the directions, whose main contents are considered as follows. 1 The machining range of parts The machining information of material: It usually includes the ordinary machining material, the special machining material and the material unable to be processed. The machining information of parts: It mainly includes the machining range and method of parts, the machining range of shape feature and the machining accuracy, which consists of the independent accuracy and the accuracy of location. The independent accuracy comes from the accuracy demands of single shape feature of part, such as the dimension accuracy for shaping, shape accuracy and surface roughness, etc. ) ) ) ) ) ) () ) ① ② 276 ③ The information of machining accuracy: It means the machining range of location accuracy. 2) The load of equipment: It includes machining task, beginning time, finishing time. 3) Machining data: It means cutting speed feed level and cutting depth. Machining experience actual machining request and machining tool should be considered to determine the machining data because of its complexity. The general steps are as follows: determine cutting depth according to the reference information of machining data or computation formula and actual machining request, and to primarily estimate cutting speed and feed level; calculate the rev of the principal axis on the basis of ; finally determine the feed level and the rev of the principal axis according to the technical parameter of machining tool; calculate the cutting speed again; checkout the machining data above according to such main machining parameters as cutting force cutting power, etc. If the value of the main machining parameter is too big, the machining data should be determined anew. There are such two kinds of method as calculation and table lookup for checkout. From what has been discussed above, the main information related to machining data can be gotten. The information are related to relevant reference for selecting machining data, the calculation of cutting speed and principal axis rev, the range and progression of the principal axis rev, feed level, the maximal power transmitted by principal axis, the power of the main electromotor, the maximal cutting force that equipment can bear, the calculation and table lookup of the cutting force and cutting power. 4) Productivity and machining cost: It includes the reference information to determine cutting man-hour, the calculation information of the cutting man-hour and machining cost, etc. (2) The special feature of function: Because it reflects the special manufacturing ability of the equipment, it is difficult to be classified and has so narrow use that it only belongs to each enterprise. It is described with some describing parameters defined by users according to their practice and users need not only input the name of describing parameters, but also the specific values[3]. The manufacturing ability of old lathe in one enterprise for boring an offset deep hole is just an example in point. All kinds of feature information of the equipment manufacturing ability in each enterprise can be described because the description parameter of the special function feature can be defined by users themselves, which lay a good foundation for establishing a flexible, open feature information database of the equipment manufacturing ability. 3.3 Accessorial feature It is a group of information of the assisted function feature, such as cooling way the way of excluding scrap iron, etc. Some equipment doesn’t have all feature information introduced above. For example, in general lathe there aren’t the storage information of cutting tool or the information of numerical control system. Only the existing information is considered when modeling, can the store space be saved and can the running speed be increased in establishing information database. 、 、 ① ② ③ ④ ⑤ 、 ① 、 4 The establishment and management of the information database of equipment manufacturing ability Under the mode of digital manufacturing, in order to highly integrate and efficiently manage information of equipment manufacturing ability, the technology of database and network can be employed. The information database of equipment manufacturing ability is established with SQL SERVER 2000, name, type, serial number, specification…, fare per hour, useable the hour, current status which is a distributedGeneral network database software. Four distributed databases, including authority management database, the management feature database, function feature database and accessorial feature database of equipment manufacturing ability, are designed. The forms in each database are planned as table 1. Machine tool Management feature : Axis: name, turning accuracy of principal axis 277 Machining range of parts Machined material: ordinary material, infrequent material, unable machined material Machined parts: the shape, type, batch, maximal weight, maximal diameter above the bed and knife shelf, maximal length of parts, maximal diameter of bar stock Machined shape feature: machining approach, shape feature, main parameter ZH, range of ZH, size accuracy and surface roughness, shape accuracy name X, machining range of X, location accuracy name W, machining range of W, the measured surface of W, datum plane of W Reference information Load of equipment: machining task, beginning time, finishing time Hard alloy cutting tool of roughly turning cylindrical surface: the material and diameter of workpiece, cutting depth, feed level, remark …… Calculation of cutting speed: formula, machining material, machining way, knife material, cutting fluid, feed level, coefficient and index in formula, remark of the rev of principal axis: formula Calculation Technical parameter: the range and progression of orthogyral rev of principal axis, the range and progression of reversion rev of principal axis the range and progression of feed level of Y-coordinate and X-coordinate, maximal power transferred by principal axis, power of main motor, maximal cutting force capable to be exerted Machining data , Calculation of cutting force: formula, workpiece material, material of cutting tool, processing way, coefficient and index in formula, remark …… Main cutting force of hard alloy cutting tool: workpiece material, cutting depth, feed level, cutting speed, main cutting force, remark …… of cutting man-hour Reference for selecting cutting man-hour: the shape LJ, material and rigidity of parts, the main parameter and range of LJ, shape feature XZH, machining parameter of XZH, dimension of processing procedure, the processing allowance, processing accuracy, surface roughness and man-hour, remark Calculation Productivity and Machining cost Information Information for checkout for checking table Common function feature Function feature Information of common lathe manufacturing ability Knife shelf: name, amount, removable distance, turning angle Spare parts: name, type, amount Cutting man-hour of lathing cylindrical surface: formula, accessorial length for testing cutting tool, remark …… Calculation of machining cost: formula, remark Special function feature: user parameter name 1, user parameter name 2, …… Accessorial feature: cooling mode, the mode of excluding the scrap iron…… Fig 1 information model of common lathe manufacturing ability The hardware used for the network management of equipment manufacturing ability information consists of the broad band local area network of enterprise the computers with good performance, etc. The B/S structure is adopted among the servers of parent company and the servers of filiale or workshop, which communicate with one another by TCP/IP protocol; The C/S structure is adopted among the servers of filiale or workshop and the computers used for equipments, which communicate with one 、 278 another by COM+; The local area network of enterprise links the internet through the fire wall, which makes it possible to access the long-distance data. Name of database Authority management Management feature Function feature Accessorial feature Table 1 information of the forms in each database Name of data form Login form authority management form General information form Information form of the main components of machine tool: information form of axis, information form of worktable, information form of cutting tool storage, information form of cutting tool shelf, information form of numerical control system Information form of spare parts range form of machined parts: information form of machined material, information form of machined parts, information form of accuracy Load form of equipment Form of Machining data form: reference information form, calculation information common form of the cutting speed, calculation information form of t principal axis function rev, technical parameter information form of machine tool, calculation and feature consulting information form for checking Productivity and machining cost forms: reference information form of confirming machining man-hour, calculation information form of the cutting man-hour, calculation information form of machining cost Form of special function feature Accessorial feature form 、 After logging in and authority permission, the forms in SQL SERVER database are visited through the access to data module ADO of Microsoft which is programmed in the VBScript language of ASP programming technology to consult network data dictionary. The forms in database are established dynamically in the way of SQL SERVER programming technology DMO in order to be convenient for users who don’t know how to use SQL SERVER to establish new forms of database. The maintenance management of the forms of database is realized by some subprograms used for appending, deleting and amending. The real-time task can be showed by contrasting the results of time function so that the equipment can be managed in time. 5 Conclusion Based on the mode of digital manufacturing, the feature-based model of equipment manufacturing ability information is built, as well as an open feature database system of equipment manufacturing ability. As a result, effective information management of equipment manufacturing ability may be realized. With the help of feature database of equipment manufacturing ability, on one hand, the exact real-time information data of equipment manufacturing ability can be provided to the different computer application systems; On the other hand, new virtual enterprise can be formed quickly and rationally. 、 References [1]Hu Qingxi. Facility resource model based on hierarchical and feature technology in concurrent environment. Mechanical engineering in china,1999, 10(11):1231~1234(in Chinese) [2]Chen Weike, Wu Bo, et al. Research and application of dynamic equipment resource modeling in heavy machinery CAPP. Mechanical engineering in china, 1996, 7(4):62~ 64 (in Chinese) [3]Li Wei. Information description method based on part-machine tool feature matching. Computer integrated manufacturing system—CIMS, 2002, 8(12):1002~1005 (in Chinese) 279