TechDraw Section Examples/fr

Introduction
L' atelier TechDraw a fait un grand pas en avant en ce qui concerne la génération de vues de coupe. Pour ne pas surcharger les pages de référence, l'objet de cette page est de donner des exemples et de fournir des noms appropriés pour les tâches effectuées.

Je fais de mon mieux pour trouver les termes corrects, mais comme je ne suis pas de langue maternelle anglaise, c'est à vous de corriger mes erreurs si vous en trouvez.

Coupes
Les coupes sont utilisées pour regarder à l'intérieur d'un objet afin de montrer des détails qui sont autrement invisibles ou difficiles à reconnaître. Le dessin comporte généralement des vues montrant l'objet dans au moins deux directions. Si une coupe est fournie, sa position et son orientation sont indiquées par une ligne de coupe dans l'une des vues.

Dans FreeCAD, il n'est pas possible de dessiner directement une ligne de coupe, FreeCAD s'appuie plutôt sur les entrées du panneau de tâches (voir TechDraw Coupe simple et TechDraw Coupe complexe).



Exemple d'objet
Cet objet n'a aucune utilité si ce n'est de décrire les différentes représentations des coupes.





Les coupes simples
L'outil TechDraw Vue en coupe crée une coupe simple qui utilise un seul plan pour couper un objet. L'outil nécessite une vue de base (propriété ) pour positionner le plan de coupe. L'axe vertical du plan de coupe est toujours la normale de la vue de base et l'axe horizontal du plan de coupe est parallèle à la ligne de coupe. En général, la vue de section est orientée avec son axe horizontal également parallèle à la ligne de coupe. L'angle entre la ligne de coupe et l'axe horizontal de la vue de base est contrôlé par des widgets dans la zone du panneau des tâches de l'outil :



La combo-boxe permet de définir un angle arbitraire. Les quatre boutons peuvent être utilisés des angles prédéfinis :

90° (up), 270° (down), 180° (left), 0° (right)



Coupe horizontale
Coupe A-A (coupe vers le haut)





Coupe B-B (coupe vers le bas)







Coupe verticale
Section C-C (section left)





Section D-D (section right)







Coupe arbitraire
Section E-E (section at an arbitrary angle)





By default the section plane goes through the center of gravity of the object. To get an offset section we need to change the values in the area.



Auxiliary view
FreeCAD lacks a tool to derive auxiliary views from a base view, but Insert Section View can also handle that:

Using Section E-E from above and changing the mentioned values to X = and Y =  the section no longer cuts the object and becomes an auxiliary view instead. Note: be careful when changing the values, large steps can crash FreeCAD!

The label was edited. The section line and one arrow have to be hidden in following steps since a single arrow is enough to properly define an auxiliary view.

Single Section
If there is only one section view in the drawing, and it is plain to see that the object is cut along a center line, the section line, including the arrows, and the view title may be omitted.



Internal section
A section view may be integrated into the base view. This case doesn't require arrows and a title either.



Complex sections
The Insert Complex Section tool creates a complex section, such as an aligned section or an offset section, that uses more than one plane to cut an object.

The tool requires a base view ( property) to place several connected section planes to cut through the object, these are defined by a 3D polyline. (This tool can also handle curves, but curved sections are rather unusual.)

The vertical axes of the section planes are always parallel to the normal of the base view. Their horizontal axes are derived from the related segments of the 3D polyline. The orientation of the Section view depends on one of the 3D polyline's segments and is influenced by the widgets in the area of the tool's task panel:



This tool provides 3 options in the combobox to handle the section line segments:
 * : only segments perpendicular to the view direction are displayed (default).
 * : all segments are displayed in true length.
 * : all segments are projected along the same view direction. Depending on the angle between a segment and the view direction the projection may be shorter than the cut area. Segments parallel to the view direction result in a single line.

Offset section
An offset section starts with a base view plus a 3D polyline, a sketch in this case.

The view direction angle must be set to a matching value to avoid unexpected results.



Aligned section
An aligned section also starts with a base view and 3D polyline.

The view direction angle can be set with and  for a coarse orientation. It has to be guessed and set to a best matching value or the result may be unexpected.



If the view direction angle is set incorrectly the result may look like this:



Auxiliary view
The Insert Complex Section tool can, like the  Insert Section View tool, create auxiliary views from base views:

An auxiliary view starts with a base view and a single 3D line placed outside the object.

The value has to be extracted from the 3D line manually. The label was edited. The section line and one arrow have to be hidden in following steps since a single arrow is enough to properly define an auxiliary view.

NoParallel section
A NoParallel section is a mixture of aligned and offset sections.

The arrow direction should have been horizontal, but the tool did not work when the value of was set to. So the sketch was rotated by 5° and said angle was set to as well.

Comparison NoParallel vs. Offset and Aligned


For some reason if the value of of the aligned section is set to exactly  the result is faulty. Only after editing the section and accepting the strange value of that the angle is somehow set to, is the correct result displayed.



Complex one line sections
The length (width) of a complex section depends on the length of the used 3D line, but the results differ from offset section to NoParallel section:



Half section
A view showing a symmetric object cut on one side of a center line and uncut on the other. The depth is usually defined by another center line.