Create bend tables for sheet metal materials

When you select Bend Table as the unfolding method in the Sheet Metal Styles dialog box, the flat pattern analyzer uses a bend table to create the flat pattern. A bend table contains bend deductions for the specified material thickness at specific bend radii and bend angles. If a specific bend angle or bend radius is not in the table, the flat pattern analyzer interpolates between adjacent cells to determine a value.

Note: A column for a specific bend radius must contain values for each specified angle row. Each cell within the table must contain a value!

Autodesk Inventor provides sample Imperial and metric bend tables as spreadsheet files. The bend deduction values in the sample bend table spreadsheets are based on formula however the true value of a bend table is the ability to provide measured results from your machinery and tooling which may not be uniform across all angles and radii. The supplied samples can be used as a starting point for the creation of tables which reflect your particular requirements.

Include an Excel bend table using the integrated editor

While the integrated editor can be used to create a bend table within an unfold rule definition most often you use all or part of an existing spreadsheet.

  1. On the ribbon, click Manage tab Styles and Standards panel Styles Editor .
  2. In the Style and Standard Editor dialog box, click the expand/collapse “+” to the left of the Sheet Metal Unfold Rule entry to display the list of existing unfold rules.
  3. Click on the Default rule to serve as the template for the rule you create.
  4. Click New along the top of the right-hand portion of the Style and Standard Editor dialog box.
  5. The New Style Name dialog box appears. Name the new sheet metal unfold rule you are about to create. Enter a descriptive name to replace the supplied Copy of Default in the Name field and click OK.
  6. The New Style Name dialog box is closed and a new sheet metal unfold rule is listed. The new rule is an exact copy of the Default rule. Make edits as described in the following steps before your new unfold rule definition is completed and saved.
  7. Set the method to: Bend Table.
  8. Set the linear units for the bend table.
  9. Using Excel, open the bend table that you want to use.
  10. In Excel, select the range of cells containing the bend angle column and the row of bend radii and all cells for the selected angles and radii. Using CTRL+X, cut these cells to the clipboard.
  11. Within the Autodesk Inventor Style and Standard Editor dialog box, click to add a thickness value and edit the thickness as required.
  12. A table consisting of rows and two columns appears to the right. Position your cursor in the empty cell located in the upper left, right-click and select Paste Table from the context menu. The cells in the integrated editor populate with the data that was cut from Excel.
  13. Click within any cell to edit that cell.
  14. When you have completed making edits to your bend table, click Save (located at the top of the dialog box) to save your edits.
  15. Click Done (located near the lower right corner of the dialog box) when you have completed making edits to your styles and rules.
Note: Rows and columns can be added by right-clicking in any cell and selecting Insert Row or Insert Column as required.

Set up an externally stored bend table file using Excel

Using the sample bend table, you specify units of measure, and tolerances.

  1. Browse to the sample bend table spreadsheets in the \Autodesk\Inventor [version]\Design Data\Bend Tables folder (which can be found under \Documents and Settings\All Users\Application Data) and double-click one of the .xls files to open.
  2. Enter units of measure. Scroll to the line that starts with /U and enter units of measure. The default is cm.
  3. Enter tolerances. Scroll to the lines that starts with /T and enter the following:
    • On line /T1, enter the +/- tolerance for sheet thickness.
    • On line /T2, enter the equal minimum and maximum bending radius.
    • On line /T3, enter the tolerance for equal minimum and maximum opening angle.
    Note: Tolerances 2 and 3 are used only under special conditions, as noted in the table.
  4. Select FileSave As, give the spreadsheet a new name, and click OK.

Edit an externally stored bend table using Excel

Use a bend table file that was set up with your units of measure and tolerances to create a bend table for each material thickness.

To begin, browse to the bend table *.xls file and double-click to open.

  1. Enter sheet thickness. Scroll to the line that starts with /S and enter thickness.
  2. Enter bend radii. Scroll to the line that starts with /R and enter radii.
  3. Edit the value of specific bend deductions, as necessary.
    Note: The bend deduction values provided in the sample spreadsheets are all determined by a conditional equation. To be of value, a bend table should be populated with empirical values determined by measuring sample pieces produced on a specific piece of equipment.
  4. Highlight the table, then press Ctrl+C to copy. Scroll down to an empty area of the spreadsheet and then press Ctrl+V to paste.
  5. Rename the table and reset the material thickness, as needed.
  6. Continue to copy and paste the table, renaming it and setting a new material thickness, as needed.
  7. Select FileSave As, select .txt file type, and then click OK.
Note: It is important to save the spreadsheet in a text (*.txt) file format. The analyzer uses the text format to calculate bends.

Sample bend table

Parent topic: Bend tables for sheet metal materials