Sheet Metal Corner Seams and Reliefs
Estimated Time Required to Complete: 30 minutes
Use with: Autodesk Inventor 2010 or Autodesk Inventor Professional 2010
ScenarioYou are optimizing the electrical box, and you need to assess the different corner types in the model and flat pattern. You will apply the different corner options, override the style settings, and observe the changes.
In this Exercise
In this Skill Builder, you learn to:
- Edit sheet metal corners
- Set sheet metal defaults
- Download the file Electrical Box.zip.
- Extract the part file.
- Edit the part and the sheet metal style.
- Have Inventor 2010 installed.
- Complete the Sheet Metal Parts tutorial or have experience using sheet metal.
- Download (and unzip) the zip file containing the source files to use during this exercise.
| ||electrical_box.zip (zip - 501Kb)|
The zip file contains an Autodesk Inventor 2010 model named Electrical Box.ipt
Sheet Metal Overview
Sheet metal features are driven by functional, appearance, manufacturing, and cost considerations. Corner seams define the gap between adjoining faces and whether one edge overlaps the other. Corner reliefs provide end clearance for the sheet metal brake die, but the resulting gap affects appearance and there is a cost for punching each relief. If the corner will be welded, then the smallest possible gap is required.
You can control the geometry and the size of corner seams and reliefs. While this appears straightforward, the combination of settings can produce significantly different results.
- Corner seam overlap
- Corner seam gap
- Corner relief shape
- Corner relief size
Sheet Metal Rules
The sheet metal rule is a collection of settings for a sheet metal part. In a nutshell, the rule defines the material and thickness, the unfolding method, the bend radius and end reliefs, the corner gap and the corner relief shape and size. Sheet metal rules are extremely powerful because they let you set defaults for your parts and they let you easily make changes to a design, such as changing the material or thickness.
- Open the Electrical Box.ipt part.
- On the Sheet Metal tab> Setup panel, click Sheet Metal Defaults to display the Sheet Metal Defaults dialog box. Click the pencil icon next to the Sheet Metal Rule selector to launch the Style and Standard Editor.
- The sheet metal rule has tabs for Sheet, Bend, and Corner settings. Note that the Miter/Rip/Seam Gap setting is on the Sheet tab.
- On the Corner tab are settings for 2 Bend and 3 Bend intersections. If you click the Relief Shape drop-down in the 2 Bend Intersection group, the list includes Round, Square, Tear, Trim to Bend, Linear Weld, and Arc Weld.
- Close the Style and Standard Editor and the Sheet Metal Defaults dialog boxes without saving changes.
Creating Corner Seams and Reliefs
Inventor has two methods to create corner seams. If you add corner seams after creating faces and flanges, a dialog provides access to the controls for the overlap, gap, and relief. If you create a multi-edge flange, corner seams are automatically created for adjacent flanges. Instead of a dialog, glyphs display at each corner, and you double-click to launch an edit dialog. This skill builder focuses on corner seams created with multi-edge flanges.
Modifying Multi-Edge Flange Corner Seams
Corner seams define how two faces meet. Multi-edge flanges automatically create corner seams between adjacent edges. The default corner seam gaps and reliefs are applied, and changes can be made by double-clicking a glyph in the graphics window. The workflow is the same whether you are creating or editing the corner seam.
- In the browser, expand Flange1 and double-click Corner2. The flanges display in preview mode and edit glyphs display at each corner.
- Click the glyph in the foreground. The Corner Edit dialog displays. There are two rows of controls. The upper row is for the corner seam while the lower row is for corner reliefs. You will learn about corner relief editing in the next section.
The checked box next to the corner seam icon indicates that the default corner seam type is overridden and editable. Click to remove the check mark, and the corner preview changes. An overlap corner seam was applied, but it is now the default symmetric type.
- Click OK. The model returns from the edit state with the updated corner seam. When you edit the corner feature rather than the flange feature, you can only modify one corner seam. Double-click Flange1 to edit the feature. You can drag the Flange dialog box off to the side since you will be working entirely in the graphics window. Click the glyph on the right. The Corner Edit dialog box displays. Select No Seam from the corner seam drop-down list and click OK.
- Click the glyph on the left. The Corner Edit dialog box displays. Select Overlap from the corner seam drop-down list. Click the Gap check box, and enter 0.06 inch. Change the Overlap Percentage to 0.5, and click OK.
- Click OK in the Flange dialog box to finish edit. Click FRONT on the view cube and compare the four corners.
- The original reverse overlap corner seam is in the upper left.
- In the upper right, the flanges end at the point where the bend zones intersect.
- In the lower left, the bottom flange partially overlaps the side, and the gap is increased.
- In the lower right, the flanges do not overlap, and the gap which is measured between the inside edges.
- Right-click on Corner2 in the browser and select Reset All Corners to prepare the part for the next section. It simplifies learning about the different corner relief options if the part has the original corner settings.
Modifying Corner Reliefs
- Open Electrical Box.ipt, if necessary, and rotate the view to look at the round corner reliefs. Double-click on Flat Pattern in the browser and zoom in on a corner relief. The bend lines have a thick dot-dash line style, and the bend extents have a dotted line style. Note in the image below that the corner relief prevents the bend extent lines from touching.
The corner relief is supposed to prevent the deformation and tearing that occurs if the bends overlap. If the corner relief is too small, Inventor cannot create the folded model geometry. It substitutes the Trim to Bend relief shape in the folded model but will still show the relief in the flat pattern.
- Expand Flange1 in the browser and double-click Corner2. Click the corner icon in the foreground, select the Corner Relief Size checkbox and enter 0.1.
Click OK to return to the folded model. Rotate the model so you can view the corner. Since this value is too small, the bends have been trimmed back to the intersection point.
Double-click Flat Pattern in the browser to activate the flat pattern view. Note that one corner relief is much smaller. Even though Inventor did not create the geometry in the folded model, it still put the corner relief in the flat pattern.
- Double-click Folded Model in the browser and press F6 to return to the home view. Double-click Flange1 and click the foreground corner icon again. In the Corner Edit dialog box, select the corner Relief checkbox and change the selection to Default (Round).
This overrides any edits and returns the settings to the defaults. Note that even though the Relief Size setting is disabled, it is still selected and retains the value. Click OK to accept the changes.
- Click the corner icon on the right side. In the Corner Edit dialog box, select the corner Relief checkbox, and then select Square from the relief type list. You can use a smaller square relief and still cut the bend zones. Change the relief size to 3/16 and click OK.
- Click the corner icon on the left side. In the Corner Edit dialog box, select the corner Relief checkbox, and then change the relief type to Tear, which simulates the no corner relief condition. The folded model will have a small gap or tear. Separate the bends and the flat pattern won’t have a corner relief. Click OK to close the dialog box.
- Click the corner icon in the back. Even though it is obscured by the preview, you can still select it without changing the view. In the Corner Edit dialog box, select the corner Relief checkbox, and then select Trim to Bend as the relief type. This trims the bends back to the intersection point.
Click OK to close the Corner Edit dialog box and click OK to close the Flange dialog box. If an error dialog box displays, click Accept. Changes to the corner reliefs can cause the iFeatures to lose their insertion points.
- Double-click Flat Pattern in the browser. Observe the different shapes and sizes of the corner relief.
- Double-click Folded Model in the browser, and then double-click Flange1. Click the corner icon in front, change the relief type to Linear Weld, and click OK.
- Click the corner icon on the left side, change the relief type to Arc Weld, and click OK.
- Click OK to close the Flange dialog box and double-click Flat Pattern in the browser. Zoom in on the linear and arc weld corner reliefs. The names refer to the geometry, not the welding process. The linear weld has straight edges while the arc weld has curved edges.
Note: The arc weld relief is intended for large radius bends. A tank or vat usually has large radius bends to simplify cleaning, and this relief provides a good gap for full penetration welds.
Congratulations! You have learned how the corner seam and corner relief settings affect the model and flat pattern.
Let’s review your accomplishments…
In this Skill Builder you: Learned the corner settings in the sheet metal rule.
- Modified corner seams in the model.
- Modified corner reliefs in the model.
- Learned how corner relief settings change the flat pattern.
Now that you understand corner settings, you can experiment with bend settings. You can also create new sheet metal rules with the corner settings your company uses.