CAD as a design object

Design called a description of the process needed to create the prescribed conditions is not an existing facility on the basis of the primary descriptions of the object and (or) the algorithm of its functioning. Design includes a significant range of research, calculation and design work, whose purpose is to get onwritings object design.

Automated called projection, which is performed during the interaction (usually in a dialog mode) user and the computer. Computer-aided design based on the systematic use of computer technology in the rational distribution of functions between the designer and the computer and informed choice of methods of machine tasks.

Aided design (CAD) - A set of design automation, interlinked with entities or group speAliste (user system). CAD integrates hardware, mathematical, computer, methodical, information, linguistic and organizational support, parameters and characteristics of which are chosen with a maximum view of features of design and construction tasks.

The main function of CAD is to perform computer-aided design for all or individual stages of design objects and their constituent elements.

Design object can be for production and technical assistance (means of production - technological equipment), manufacturing processes, as a result of which projects objects are embodied in material form, buildings, engineering structures, vehicles, communications, computing, organizational and managerial system etc.

Project is the set of project documents, corresponding to a given list. Designing the content is a process of processing a certain amount of various information. Output process is a description of the desired object (the information model in the form of diagrams, drawings, diagrams, specifications, schedules and other documentation), which is necessary and sufficient for the material and the material embodiment of the idea of designing a concrete physical object.

To create a CAD system is required: improving the design through the application of mathematical methods and the latest computer technology, automation of search, processing and delivery of information, the use of optimization methods and contingency planning, effective use of mathematical models designed objects, creation of databases containing systematic reference information, providing automation of the design, improving the quality of project design documentation, harmonization and standardization of design methods, training of professionals in the field of CAD, interaction design departments with automated systems at various levels and purposes.

Creating CAD is a complex scientific and technical challenge. The introduction of CAD systems requires significant capital expenditures.

Mƈ You can mention some basic features of building CAD.

CAD is a man-machine system. Important role in it belongs to the engineer, is developing the project of technical means. A man decides to CAD problems, formalization of which has not yet been achieved, as well as tasks that based on its heuristic capacity more efficiently than on a modern computer. One of the principles of construction and operation of CAD is the close interaction between man and computer in the design process.

CAD is a hierarchical system. It implements an integrated approach to automation at all levels of design. Hierarchy of levels of design is reflected in the structure of special software (software) CAD as a hierarchy of subsystems.

Composition and structure of the CAD

Constituent structural parts of the CAD system are the subsystem. In the subsystems through specialized complexes solved by means of functional sequence of tasks finished CAD.

Projection subsystem perform procedures and operations to obtain new data. They are object oriented and implement a stage of design or group of related design problems. Examples of projections subsystems are: schematic design product, design of parts (hull, shafts, gears, etc.), design of technological processes of assembly, machining and other types of processing.

Serving subsystem have a system-wide application and are used to ensure the functioning of subsystems of its own design, as well as for registration, transfer and display the results obtained in them. Examples of service subsystems: a database management system, subsystem documentation, graphical input-output.

Complexes of funds attributed to industrial products to be manufactured, replication and use of CAD. They are documenting as Specified products. Complexes of funds are subdivided into complexes of one kind of (technical, software, information) and combined (Fig. 2.1). The first includes complexes and (or) components of one type of security. The latter contain a set of complexes and components of various types of software. Combined complexes divided into:

- program-me­todicheskie (PMK);

- software and hardware (TAP).

Fig. 1. Types of systems and components of the CAD

Classification CAD

CAD classified in order to address several problems:

- preparation of a consolidated formalized description of the CAD system according to the established classification of signs;

- designations CAD developed in organizations of various industries;

- Planning values increase the level of automation of design, efficiency CAD;

- set conditions for determining the technically based norms for the creation, operation and development of CAD necessary resources (expertise, technical resources, information, energy, etc.).

Signs characterizing SAD include: type, variety, complexity of design object: level, integrated automation design, nature, the number of documents produced by the project, the number of levels in the structure of logistics CAD. To get an idea of the specific CAD system, it should be assessed on all grounds.

Type Design. CAD systems are classified on the basis of nine groups:

- engineering products;

- instrumentation products;

- technological processes in machineStructure and instrumentation

- construction projects;

- Techno­logical objects in the building;

- software products;

- organizational systems.

Variety of objects of design. Special designations objects of design is not established. Their point and coded according to the current in each branch of industry systems refer to the documentation designed system objects.

The complexity of design object. On this basis distinguish CAD:

- simple objects with the number of parts to 10;

- objects of average complexity;

- complex objects;

- very complex objects;

- super complex objects.

Integral part of design object that constitutes a product, is a part. If the object of designing a manufacturing process, then determine its component parts is much more difficult. In this case the technological process is divided into elementary technological operations or shared object on the design of conventionally produced according to the nomenclature of technological documentation.

Level design automation. On this basis distinguish CAD:

- nizkoavtomatizirovannye (up to 25%: the design procedures);

- sredneavtomatizirovannye (25 -50%);

- highly automated (over 50%).

The complexity of design. On this basis CAD subyayut:

- Single-stage;

- multiphase;

- complex.

If the automated any one stage of the design of a particular object, then the SAD relate to the first group. Where to automate all stages, CAD is complex.

Released design documents. CAD divided into five groups according to their outputs of project documents:

- on the tape and (or) sheet;

- on storage media;

- of photocarriers;

- combined (issue documents in two or more types of media).

The fifth group left back.

Number of project documents. Number of documents produced by the project characterizes the performance of CAD. In accordance with this distinction CAD small, medium and high performance.

The number of levels in the structure of technological support. On this basis CAD divided into one-, two-and three -.

Basis one-level complex of technical means (CTS) is a computer medium or high performance and full-time set of peripherals. These computer program performed data processing and storage. One or more computers form a level, which is called a central computing system (PPM). If you are using a minicomputer, the CTS is called automated workplace (AWP).

For effective communication with the user's CAD system and solutions, in addition to the most complex program procedures, a large number of simple tasks in the latest organize the second level in the computer-integrated manufacturing.

Three-level CAD, besides technical means of two-level system are peripheral and software-controlled equipment: complex monitoring of control programs for CNC machines, drawing machines, systems for manufacturing photomasks.

Types of CAD

Software for CAD

The most difficult step in creating CAD is the development of software (MO). Last largely determines the performance and efficiency of CAD in general. DoD CAD is based on algorithms, which are developing software (software) CAD. DoD CAD includes a variety of elements, among which are invariant - the principles of the development of functional models, numerical methods for solving equations, finding the extremum. Appointment and way to implement DoD CAD divided into two parts:

- mathematical methods and building on the basis of their mathematical­cal object model design;

- formalized description of technology of automated­tion design.

Information support CAD (IO CAD)

The main purpose of the IO CAD - Decrease the volume of information required in the design process from DeveloperAnd avoidance of duplication of data in the application, software and technical support of CAD.

The basis of the information security (IO) are the CAD data that designers use to develop design solutions. Collection of data used by all components of CAD is its Information Facility. Data can be presented in different media in the form of any documents containing background information about the materials, types of equipment, model design decisions, options, elements, information on the status of current developments.

IO CAD consists of a description of standard design procedures, standard designs decisions, typical elements, Components and their models, materials, numerical values of the parameters and other data.

Furthermore, IO CAD includes rules and design standards contained in the relevant normative and technical documentation, as well as information on how to document the results of design. Structure and content of the IO CAD, as well as the nature of its use depends on the degree of development Database.

Data IO usually grouped in separate arrays, each of which relates to a particular object descriptions. Such arrays are called File. All set File forms databaseWhich can be reused when designing for different stages and levels.

The data, which are the result of any single conversion process may be the source for another process of transformation. The main purpose of the IO is the CAD information management fund, which is to ensure the creation, support and organization of data access. IO CAD is, therefore, the totality of information collection and means of reference.

All varied in content information used in CAD, is accumulated in the database (DB). Last created on the basis of a uniform classification system, coding the entire set of information on the form, as well as the centralization of databases to the same database could use and technology designers.

Information used in CAD can be divided into declarative (eg, description of the typical elementary surfaces, form elements and details; model of technological processes of these elements or blanks in general) and procedural (eg, procedure of formation process of picking routes, machining).

Declarative information may be statistical or dynamic. Static is characterized by few changes. The dynamic information consists of intermediate and resulting data of the design process. Dynamic information becomes static when the CAD system is programmed for a constant updating of its database, due to newly occurring cases of design (the creation of precedents).

In the database, in general, accumulate: for policy information, which is a task for the design, standards, guidance documents and standards of enterprises; regulatory information, representing the classifiers, the rules of coding and decoding methods of calculation and design, analysis and synthesis, simulation, practical recommendations of the heuristic nature of summarizing the experience of manual design, etc.; factual information which is non-quantitative and quantitative reference, catalog and passport data, typical solutions, prototypes, analogues and precedents.

Original form of information can be documented (eg in the form of "technological map processing model details"), iconographic (eg, drawing tools, devices) and factual (eg, the technological parameters of the range equipment, taken from his passport).

Database is constantly updated with information on the development of systems of classification and coding. This allows, for example, to effectively use the principles of group technology assembly or processing and to avoid re-development through the application instead of them made earlier developments.

CAD software

CAD software (In CAD) is a collection of computer programs and their associated operational documents necessary to carry out computer-aided design. Completeness, properties and characteristics of the software - define the functionality, scope and effectiveness of CAD.

CAD software consists of a document with the programs, programs for all types of storage media, as well as operational documents (instructions on the application, etc.).

The set of computer programs presented in the specified form, required to perform any procedure, the machine is called the package of applied programs (PPP).

Some software that serves to manage the processing of information by computer, called the operating system (OS).

The software is divided into system-wide (common) and application (special).

Enterprise-wide software used to organize the functioning of technical means.

Application software is focused on a specific subject area of computer-aided design.

Programs included in the software should:

- ensure economy of use of computer resources (memory and CPU time), ie be effective;

- have reliability;

- have structural and modular, which lies in the fact that the challenge can be divided into simpler, each of which corresponds to a specific software module;

- allow modifiability, ie made to the program changes should not impair their quality;

- allow portability to new types of computers and technological problems;

- be consistent, ie data that are used in two or more programs that should be included in the numerical arrays that do not require correction in the transition from one program to another;

- be "friendly", ie easier to use.

Linguistic Support CAD

Linguistic Support CAD represents the totality of the form of a given language (including terms and definitions, rules of formalization of language, as well as methods of compression and the deployment of the texts) needed for computer-aided design. Languages that are used in computer engineering, are algorithmic. They serve to define specific algorithms of information processing and built through a set of symbols and rules of the language.

With CAD used programming languages and languages spoken man with a computer.

With programming languages are compiled programs that are part of a system-wide or application software. These languages are divided into the languages of low and high levels.

Low-level language - Machine languages, operators of which consist of machine instructions, and assemblers, ie Languages symbolic coding, which used mnemonic symbols of machine instructions.

High-level languages not imply knowledge of the user machine language. They are not associated with a particular type of computer. Therefore possible to translate programs from one computer to another. A team of high-level language is translated into several teams of machine code. Expressions of language consistent with its scope and have a rigid tabular form. To the language of this level algorithmic programming languages include FORTRAN, BASIC, COBOL, ALGOL, PASCAL, APL, C + +, etc.

Input language CAD oriented to the problem of designing objects a certain area, ie is problem-oriented language (singing) and is typically for use in interactive mode. In some cases, singing is constructed so that the description of any task or assignment on its decision to include mainly original terms of physical and functional content. The transition from the physical and functional description of a problem to a computer program then automatically executed by the translator. In other cases, for example, in solving problems of geometric type, singing together means algorithmic high-level language providing computational solution of mathematical problems and the special linguistic resources modeling geometric objects. Algorithmic language translator, with a complement of special programs.

Thus, singing may describe in detail:

- job design, ie describe the set of notes and restrictive conditions, forming a "model release";

- objects considered in the design (to describe the set of all variants of all the objects that appear as "selected factors"), all intermediate and resulting decisions;

- all the procedures that must be done to get a solution.

The first two conditions define the singing as a language for describing the object, the third - as a language for describing the job.

Input languages CAD must meet the following basic requirements: fully describe any facilities for the design-oriented CAD system, this, you have easy alphabet and syntax of the text, as well as the familiarity of geometric constructions; provide concise entries; ensure the uniqueness of interpretation and the interpretation of text and graphic constructions; prevent opportunity to develop and adjust the language in accordance with the improvement of CAD.

Technical support of CAD

Technical CAD software is a set of interrelated and interacting hardware (components) to carry out computer-aided design, with each tool performs a specific function of design.

Technical facilities are classified as follows.

- Training and data entry designed for the automatic preparation, encoding, visual inspection and editing of input into the computer alphanumeric and graphical information, as well as the application of data on different storage media information.

- Program data provide remote communications facilities through various channels of communication.

- Software processing, data is digital data reception, processing, accumulation and withdrawal of storage media, display devices and communication channels.

- Archiving of project solutions perform storage, control, restoration and reproduction of data on project decisions, etc.

Methodological Support CAD

Under the methodological basis for CAD to understand set of documents setting out the composition and rules of selection and operation of computer-aided design tools needed for its implementation.

Organizational support CAD

Under the organizational maintenance CAD understood as a set of documents setting out the structure and functions of the company or organization, interacting with the CAD, as well as determining the order of reference documentation. Organizational maintenance of CAD as an independent component contains various provisions, regulations, orders, qualifications, staffing plans and other documents governing the organizational structure of departments of design organization, as well as the interactions of entities with the means of computer-aided design.

CAD in computer-integrated manufacturing

Reflecting the prevailing practice of consistent implementation of processes of design and development of technologies, CAD usually divided in at least two basic types:

- CAD product design (CAD I);

- CAD technology for their manufacture.

CAD design products (CAD) perform volumetric and flat geometric modeling, engineering analysis, evaluation of design decisions, getting the drawings. Andssledovatelsky stage CAD products are sometimes released in a separate automated system research.

CAD technology manufacturing (CAM), which in Russia is called the automated system of technological preparation of production (ASTPP). The task of CAD process (CAD TA) is the development of technical documentation (route, operating), brought to jobs and with varying degrees of detail the future process of manufacturing parts.

A separate, unrelated, operation systems, CAD and he gives to the economic effect, the size of which can be substantially increased integration of these systems (Fig. 2) by Sarah. Such Integrated System SAD/ CAM at the information level is supported by a unified database that stores information about the structure and geometry of the product (as a result of design in the CAD) On the production technology and equipment for UP CNC (as background information for processing in the system itself on the equipment with CNC).

Figure.2. Elements of an integrated system

At present the main trend in the achievement of high competitive ability of Western companies is the transition from individual closed CAD and their partial integration to full integration of technical and organizational standpoint. Such integration is associated with the introduction of models of computer-integrated manufacturing (TRC), or in English withIM.

Fig. 3 shows the main stages of construction and logistical CAD, realized withIM.

Figure.3. Basic systems CIM

Practical experience of establishing and operating withIM shows that the strategic concept of CIM should cover the design, manufacture and marketing of products for computer-integrated manufacturing. Planning should begin with market research and end with issues of delivery of products to the consumer.

Building CIM includes addressing:

- Information Management (departure from the principle of centralization and decentralization of the transition to a co-ordinated at each of the considered­GOVERNMENTAL levels both through the collection and accumulation of information within individual subsystems, and in the central database);

- processing (docking and adaptation of software of various subsystems) and the physical connection subsystems (interfaces, ie docking, computer hardware, including the use of computer networks).

Innedrenie CIM significantly reduces the total travel time of the order by reducing the transfer time from one area to another and reduce the downtime when making your order, and also due to the transition from sequential to simultaneous processing, increases productivity by eliminating or drastically reducing repetitive manual operations, training and data transmission (eg , Machine mapping of geometric data can be used in all parts of the construction products).



Literature

«SOFTWARE PROBLEMS OF ROAD TRANSPORT». Textbook Novgorod State University named after Yaroslav the Wise site at http://www.novsu.ru/npe/files/um/1128/umk/POZAT/Glava_2/Glava_2.htm