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INTEGRATION OF CAPP AND CAD/CAM SYSTEMS

Stroka, R. & Helis, A.

Ing. Roman Stroka, Ing. Alexander Helis Žilinská univerzita v Žiline, Strojnícka fakulta

Katedra merania a automatizácie, Velký diel, 010 26 Žilina, Tel.: ++421 41 5132810, 5132814, E-mail: stroka@fstroj.utc.sk, helis@fstroj.utc.sk

Abstract: In the paper is described creation of external form technological process, with application CAD/CAPP or CAM/CAPP systems. Connection CAD/CAM and CAPP systems by the external software or integral language is in the first partition of the paper. NC programme, which is one from external form technological process, is output from software. This software is result of connection CAD and CAPP systems. This connection is described in the second partition of this paper.

INTRODUCTION

Realisation of real CIM system supposing connecting of information dates single systems. Single systems, inside CIM system, with full integration connecting predvýrobnú, výrobnú and povýrobnú phase production. Absent or small integration causing decrease of effects work, of qualitative indexes and total decrease of economic production rate factories. Single systems are often buying without of solid more analyse systems, which is in factory working. If we want the systems connecting, originate problem. Is here problem of incompatibility dates. Interfaces between single CA systems are generator contradiction. By separate using of systems makes “island of automation”. In the middle of they is very high quality of work and effects but communication between they stagnate. And so effects all CA systems are below. Is it a lot of executive software products, which but working isolate.

INTEGRATION OF SYSTEMS

There has been successful integration of CAD – system, supporting design of technical documentation and CAM system, supporting production of parts to one safety working CAD/CAM system. After integration of CAD/CAM systems it is logical to focus on to next system, which follows in the realisation process of the part, that is CAPP system. There exist a lot of CA systems either in CAD/CAM systems or in CAPP. In the ideal CIM system the data, gained in CAD/CAM module, used in CAPP module through database.

The base of the whole problem is, that output files of one part of suggestion are not input files of next part. This problem is solved by duplication of saved data in form of documentation, plan of tabs. Saved data are not maximum used, what leads to decreasing of effects of computer using and k increasing of error occurring. There is necessary to focus on the following areas to solve problem of working areas integration and relevant operations in CA systems:

?? conservation and transmission of dates – field of databases, computer nets, processing of various data types and similar

?? unification of data formats – field of standards and respecting of them

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In the communication between CAPP and CAD/CAM systems there is necessary to provide transmission of two types of information:

?? constructive – (geometric) data, describing design of part ?? technological – data describing way of machining of part

Therefore this problem needs to be split into two single parts, but solve them in the interaction.

In CAM part of system are information describing sequence of operation machining of product, information about machines, tools, gripping, time of machining etc. This information create base, from them is possible make process plan. Process plan is base of CAPP systems. Problem of integration is possible solve by two way. The first from of possible approaches is transformation of standard files by interface. The second approach is using aided of build in programming language of graphic system.

INDIVIDUAL WORKING MODULE

The program, which mange and transform data both systems, could be solution in today’s conditions. System SYSKLASS is working with databases files. These files are without problems available. System ALPHACAM is working with data, especially geometric, in own format. This data are, without more extensive intervention to main system, difficult available. Important entries are in format, which make possible processing. These entries are final information about single technologic operation. This data is possible read and transform to form of necessary to input to system SYSKLASS. Communication between systems is in two levels, designing and technologic. Designing information are in format DWG and DXF. Technologic information is in format DBF. ALPHACAM generate description operation and NC programme and save in format ANC. From save file is generating simple verbal process plan and export to databases of SYSKLASS.

Fig.1. Communication between systems

MSVC

RMAT

TLGP

TLGNAR

NC PROGRAM

DXF/DWG

TOOLS

PROCESS PLAN NC

PROGRAM

GEOMETRY

NC PROGRAM

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The work in the Communication Manager had following rules:

1. Choosing of the project by the project name or part name from system SYSKLASS ?? the possibility to load the choosing project and than to search of the part design or workpiece,

technological process, tools or NC program 2. The work in system ALPHACAM, modification of existing part design or creation of new part

design. ?? the generating of operation and NC program list ?? the finish work with system ALPHACAM

3. The generating of simple verbal technological process in Communication Manager (fig.3) ?? the possibility to rating new part design, technological process or NC program to the database of

system SYSSKLAS with help of Communication Manager. ?? the possibility to continue in work with new part after the classification of this part.

Is creating effective instrument to quickly communication between both systems. Using CAD/CAM properties of system ALPHACAM, under production new product, are at the same time obtained input information for databases of system SYSKLASS. This connection markedly to hurry filling of databases. System SYSKLASS may be using in the short time after application to firm.

BUILD IN PROGRAMMING LANGUAGE

CAD/CAM systems have usually built in programming language – API (Application Programming Interface). The ALPHACAM API is an OLE (Object Linking and Embedding) automation-programming interface to ALPHACAM. The API contains many functions that can be called from VBA (Visual Basic for Application). The function can also be called by VBA in programs Excel, Access, Word etc., or by programs or DLLs (Dynamic Link Library) created with Visual Basic, Delphi, C++ or any other language that supports OLE automation.

The API function provide the programmer with direct access to ALPHACAM functionality such as creating geometries, machining them, controlling the input and saving of files etc. The API interface uses an object-oriented approach. ALL of the functions are methods or properties which apply to an object. All Advanced modules, in SYSTÉM ALPHACAM, include the ability to run externally created Parametric macros. The API does not replace Parametric macros, but is an additional, more powerful, way of control-ling the functions in ALPHACAM module.

A COLLECTION is an object that is a list of objects. VBA provides a general Collection object which can be used to hold any kind of object. These are usually used to give access to the objects. In AL-PHACAM a Collection for a particular type of object has the same name as the object, with “s” added on the end. For example, a Paths object is a Collection of Path objects. The number of objects in a Collection is given by the Count property.

ATTRIBUTES are feature of the API which let a VBA Macro (or DLL or EXE) attach data to a Path object. (Geometry or tool path.) Each attribute may be an integer or floating point number, or a string. Each attribute may be read and written using the API, and can be read in the Post processor. They are saved with the ALPHACAM drawing eg in the AMD file. Each attribute is identified by string. Because the attributes are saved in the drawing file and a user may have more then one add-in using attributes, we need to have a way of choosing the string identifier so that it is unique. The attributes is set and returned as a Variant. VBA will automatically convert between a Variant and string or number. Attributes can also be

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attached to MillData (or TurnData or WireData) object. The attributes will then be copied to the resulting tool paths when eg the RoughFinish method is used. Attributes are stored as Variants. A Variant is a vari-able stored as a number giving its type and another variable storing the data. The type is determined by the type of the variable or expression used to set the attribute.

ERROR HANDLING. Some ALPHACAM API methods will “Raise an Error” if they are unable to do the required action. “Raise an Error” means that the macro will stop and VBA will display a diaog box describing the error. For example, if the Application.SelectTool method is called with an invalid tool name, the dialog box will display the next “Error selecting tool”. The user then has the option of ending the macro or debugging the code.

SYNTAX. ALPHACAM API objects have Methods . Methods are functions that may be called to perform tasks in ALPHACAM. For example, the MillData object has a RoughFinish which is equivalent to the Rough / Finish command in the Machines menu in Mill module. ALPHACAM API objects support a Dual interface. To call a method use the syntax:

ObjectVariable.method (arguments)

LPHACAM API objects have PROPERTIES. Properties are numbers or text strings which may be read and written. For example, a Path object has a property called Closed which will be True if the ge-ometry or toolpath is closed. CONSTANTS. Some of the API methods and properties use named con-stant values eg acamINSIDE or acamToolBALL. These all start with “acam”. In VBA Project inside AL-PHACAM they are defined automatically. In externally created program or DLL they be used by importing the Type Library.

OBJECTS have method and properties. To access an object you need an object variable. Usually you start with the Application object. In VBA inside ALPHACAM, the Application object is always available as App. In a program run outside ALPHACAM eg using Visual Basic or VBA inside Word or Excel etc first set a reference to the Type Library for the required ALPHACAM Module, using the Tools / Reference command in the VBA or VB IDE.

INTEGRATION CAD/CAPP SYSTEMS

Integration of CA systems isn´t just that systems can communicate together, they must „understand“ together too, that is they must share date that often are saving in different types of models with different information’s format. It depends at systems that must by integrated together. If it‘s CA systems with similar character (for example CAD systems), then their communication mainly depend at supported by transfer of protocols DXF, IGES, SAT, SET, VGA, VRML, STEP, DWG etc.

The integration of CA system wiht different character their function is commplicated.The integration of CAD of CAD/CAM system with CAPP system is most complicated. It‘s mean makeing integration of every systems which are intended for constuction added design (CAD) and systems intaded for computer addied process planing (CAPP). This two engineering activities are very related together and interlock. It‘s necessary to transfer geometrical (design and dimensions) and nongeometrical (material, tolerances, buck-ling etc.) informations between this two systems. This informations affects in large area planing of technolo-gy of production. There are the reasons of troubles of data integration in different computer systems. The problem exist by the transformation of differnet data models and often in ambiguity of data strukturs too. Without this mentioned data it‘s imposible to crate technological documentation as output CAPP system.

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Fig.2 CAD/CAD integration – the transfer of geometrical information about part between CAD systemsfrom different makers

Fig.3 CAD and CAPP integration: the transfer of geometrical and nongeometrical in-formationsí about part

Fig4 CAD a CAPP integrtion: the transfer alongs geometrical and nongeometrical in-formations about part by using STEP standard.

NEUTRAL FORMAT AND INTEGRATION CAD/CAPP SYSTEMS

Data formats DXF, IGES, SAT, SET, VDA, VRML, enable just transmission the geometrical in-formations. Problem of transmission nongeometrical informations is handle often by various accessory mo-duls, extendions and tools created in various program languages whitch are implemented in CAD systems (for examle AutoLisp in CAD system AutoCad) or the external procedures are calling witch are created in Delphi, C++, Visual Basic. This procedurs recored into internal and special created files mainly nongeome-trical data. Such problems solving isn‘t standard and requiste programing skill and knowns of inetrcomm-position CAD system and internal CAD database. The example of this nonstandardconecting CAD and

Geometrical date

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CAPP system is teaching CAD/CAPP system. TXT file was here generated by using internat implemented language AutoLisp from the partdesign (was created in AutoCAD R14). It was generated by destructural designing. That is‘t example of integration of two systems (Fig. 2). TXT file created after this manner and information into it are prepearing by external application. This external application is created here in Visual FoxPro and output is NC program like one of many forms of representation the technological documenta-cion.

NEUTRAL FORMAT STEP

Transmission problem with no geometric entry promote solve neutral format STEP. This format solves interpretation and exchange entry of production model with ample quantity of information that we need for upgrading connection application software with straight valuation and with minimal interaction hu-man. Production model is assumption of information power for purposes generate job description for pro-duction, straight test of quality and for execution production subsidiary functions. Seldom hold a production entry element how for example is technical conditions modification material. In addition was formation vi-sion, that standard will be support full measure no geometric entry’s how for example are: scale tolerance, material property and face rough. Geometric model includes planes presentation for frontier and construc-tion form plain geometry. This connection with no geometric entry and with relative information’s come out from idea, that transmission system will be use standard to formation complete production model.

When we compare format STEP for example with format IGES, so format STEP have a fortiori information’s, that are needs and important in production process component. From this and same from table resulting that from this aspect description production entry is this format (STEP) most effective. As for needs production technological documentation are needs complex data about component equally geometric as well as no geometric nature. For integration CAD and CAPP systems is format STEP as best instrument for they’re intermitting.

The article is output from VEGA project of MS SR Nr.1/7088/20 "Object oriented approach for design of process plan - theoretical basis for building of intelligent CAPPsystem"

REFERENCES

[1] Cubonová N.,Kuric I., Automatizácia technologickej prípravy výroby, návody na cvicenia VŠDS SjF Žili-na, 1996 [2] Kuric I., Technológia automatizovanej výroby, ucebné texty – elektronická verzia, fstroj.utc.sk/web/kma/student/tav.htm [3] Novák-Marcincin J., Petík A., Pocítacová podpora výroby (CAM) – neoddelitelná súcast retazca CAD/CAM/CAE. WEB journal: fstroj.utc.sk/journal/sk [4] Koncír M., Programové zabezpecenie komunikácie CAD/CAM systému AlphaCAM s CAPP systémom SYSKLASS. Diplomová práca VSPRM/ 189 - 2000. Žilinská univerzita Žilina, 2000 [5] Kuric I., Stroka R.., Cubonová N., INTEGRÁCIA CAPP A CAD/CAM SYSTÉMOV, MM PRUMYS-LOVÉ SPEKTRUM c.9, september 2000, Praha, Ceská republika, str. 32 [6] Licom Systems Ltd., AlphCAM API – Reference Manual, AlphaCAM 99 Version, 12.10.1999

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[7} Kuric I., Neaga I.,: STEP – prostriedok integrácie CA systémov, WEB casopis Pocítacom podporované systémy v strojárstve, 1.11.1999, ISSN 1335-3926 [8] ISO 10303: Industrial automation systems - Product data representation and exchange , 1996 [9] ISO 10303 – Part 1: Overview and fundamental principles, 1996