Using AutoCAD features to get the orthogonal projections of a solid model

1. Using AutoCAD features to get the orthogonal projections of a solid model Author: Elena Mereuta, University “Dunarea de Jos”of Galati, Romania

2. Abstract The paper presents the steps to be followed when we want to get the orthogonal projections from a complex solid model. After creating the solid model, the desired view ports, the user has to create and manipulate the layers on each view port and the section and make different profiles in order to get on each projection the desired profiles (internal or external) and the sections.

3. Review of the descriptive geometry methods • In order to solve the intersection of solid bodies, the descriptive geometry offers some methods that lead to the solution. Such methods aim either acquiring the intersection points of the edges of one body, with the faces of the other, or acquiring the intersection segments of the faces of a body with another body faces. This is the case of the polyhedrons. When about cylinders and cones, or spheres the solutions are much difficult to obtain, as for the necessity of finding a large number of common points, in order to picture the most appropriate shape.

4. The proposed method Steps: • ·      Solid modelling of the complex body; • ·    The command VPORTS offers the possibility of defining a desired number of view ports; • ·     The system variable Tilemode offers the possibility of changing from model space to paper space; • ·     We use the MVIEW command to get the mobile views in paper space; the Restore option leads to retrieve the view port configuration previously saved; • ·   The command VPLAYER offers the possibility of defining new frozen layers in all view ports. Their number is according to the necessities; • ·     The first view port is for the vertical plane projection and, this time, we get the profile of the complex model after we change the point of  view in order to get the desired projection. Automatically, two layers will be created: one for the visible edges, and one for the invisible ones. The same step is followed for the horizontal and lateral plane projection; we use the DRAW- SOLIDS-SETUP –PROFILE command.

5. Examples • The intersection of a quadrilateral right prism with the base in the horizontal plane and a triangular right prism with the base in the lateral plane that defines the inward shape

6. The intersection between a circular right cylinder with the base in the lateral plane and a rectangular right prism with the base in horizontal plane, as internal shape

7. The intersection curve of a cylinder and a sphere

8. The orthogonal projections of a tenon

9. The intersection of a pipe with a hexagonal right prism

10. The intersection curve of a torus and a frustum of a cone

11. Conclusions • In order to better visualize the intersection curves obtained in different cases we can use the methods proposed in this paper that uses the AutoCAD features for solid modelling of the main bodies. We create and manipulate the bodies in order to show the intersection shape. It is necessary to define the desired projection, to define appropriate layers and to manage them according to the aims