A Graphical Post Processor For An Educational Cnc Code Generator

Abstract

The authors have developed a post-processor with a graphical user interface for use with a CNC code generator that was originally intended to operate one particular vertical milling machining center. The CNC code-generator, VAL-CAM, was developed by one of the authors for teaching part of a CAD/CAM course for engineering technology students. In order to make the CNC code more universally applicable, a post-processor has been written as a stand-alone program. The program not only converts the current CNC code to operate other machine tools, but also allows the addition of machine tool functions that are not included in the existing CNC code. This will allow engineering technology students to use a variety of CNC milling machines that have recently been, and may at some future time be, installed at Buffalo State College.

The program was written in Visual Basic to run under the Microsoft Windows environment, and hence on any PC platform. Modules have been written for existing CNC milling machines. The modules allow for capabilities of new machines to be added above and beyond those capabilities already incorporated. For instance, the machine for which the VAL-CAM program was originally written does not have an automatic tool changer, whereas one of the recently installed machine tools does have such a tool changer. The program module for this new machine allows the user to specify the codes that are used by the new machine that will effect an automatic change of tool. A variety of standard and non-standard codes are also provided so that the user can tailor the code to operate most new machine tools.

The significance of this project is that the generality and modularity of the post-processor lends itself to utilization in similar laboratories at other educational facilities.

Introduction and Problem Statement

A CNC code generator, VAL-CAM1,2,3, was developed by one of the authors for teaching part of a CAD/CAM course for engineering technology students. This program is couched as an attachment to AutoCAD and is written in AutoLisp, a command language affiliated with AutoCAD. The program used geometric data from a drawing currently on the AutoCAD screen, and, after the user supplied choices for various tooling and milling options, produced CNC code for one particular vertical milling machining center, as well as a graphical representation on the AutoCAD screen of the milling process. This process provided an instructional tool for learning

Proceedings of the 2003 American Society for Engineering Education Annual Conference & Exposition Copyright © 2003, American Society for Engineering Education