KOMPAS-3D v23

When determining the flat pattern length using the above methods, the flat pattern parameters (K, BA or BD) can be specified arbitrarily, however, subject to the existing constraints.

Dependence of the flat pattern parameter on the thickness of material, bend angle and radius can be determined experimentally, for example, and presented in the form of tables. In KOMPAS, they are called tables of bends and can be used for setting flat pattern lengths.

The type of the table is based on its contents:

•table of position coefficients of the neutral layer;

•table of bend amounts;

•table of bend reductions.

Bend tables are stored in files with the extension loa.

KOMPAS-3D is supplied with four tables of bends:

•two tables of position coefficients of the neutral layer:

•Sample1_K_factor.loa;

•Sample4_K_factor.loa;

•table of bend amounts Sample2_Bend_allowance.loa;

•table of bend reductions Sample3_Bend_deduction.loa.

Examples of tables of bends are stored in the folder the path to which is specified by the SHEETMETAL system variable of KOMPAS-3D. By default this is a subfolder of the ...\Sys\SHEETMETAL main system folder.

Format of the Table of Bends

Table of bends is a text file with the loa extension. Table files are available for viewing and editing in any text editor, for example, in Windows Notepad. Below is the fragment from the table of position coefficients of the neutral layer.

# Table type - table of coefficients K

1

# Interpolation - use linear interpolation

1

<0.5> 1.0 2.0 3.0

0.0 0.375 0.415 0.439

360.0 0.375 0.415 0.439

 

<1.0> 1.0 2.0 3.0

0.0 0.350 0.375 0.398

360.0 0.350 0.375 0.398

Tables of bends are built in accordance with the following rules.

•Measurement units are not indicated in the table. Linear values are measured in millimeters, angular values – in degrees.

•Rows starting with a "#" character are the comments.

•The table may contain empty rows. They are ignored when the table is processed.

•The first value in the table defines its type:

1 – table of coefficients K;

2 – table of bend amounts BA;

3 – table of bend reductions BD.

•The second value defines whether interpolation could be applied to determine intermediate parameter values:

0 – do not apply interpolation;

1 – apply linear interpolation.

•The table of bends consists of several data blocks. Each block contains values of the K, BA or BD parameters for various thicknesses, bend radii and angles. All blocks have identical structure.

•The thickness of sheet material is a constant value for the data block. Its value is given in broken brackets. For example, in the above table fragment the thickness value is found in the upper left-hand corner of the block.

•The first row in the block contains values of the bend radii. They are given in ascending order from left to right.

•The first column in the block contains values of the bend angles. They are given in ascending order top down.

•Blocks in the table are arranged in the order of increase of material thickness.

•Values in the table are separated by spaces or tabs.

Using Tables of Bends

To use a particular table of bends in sheet parts, specify this table file in the sheet solid properties settings dialog or select the table using the Modeling — Sheet modelling — Bend table — Select command.

To obtain a flat pattern parameter from the table of bends for bends of a sheet element to be created or edited, do the following.

1.Expand the Flat pattern list in the Length Determination Method section on the Parameters bar.

2.Select the Bend Table row in the list. The name of the table of bends selected during setup of the sheet solid properties will appear in the Source File field.

If the Bend Table option was enabled when configuring properties of the sheet solid, then Bend Table will be a default method for determining flat pattern lengths of all new bends. In this case the above actions are not required.

After you enter values of the bend angle and radius, a flat pattern parameter matching these values will be selected from the table of bends. It will be used for unfolding the bends of the created sheet element.

When building a sheet solid or shell ring, the name of the Source File field is the link. After clicking the field, the Open File dialog box will appear where you select the required table file.

When you create the first sheet element in the model for which the table of bends is used, all data from the table will be stored in this model. The reference of the model with the table file is not formed.

All bends for which the flat pattern parameter is taken from the table will use the data stored inside the document. You can edit or delete the source table file. This will not change the bend parameters.

Changing Table of bends

To use data from another table file for bends built with help of the table, change the table stored in the model using one of the methods.

•Run the Modelling – Sheet modelling – Bend Table – Select... command. A Select File dialog box will appear. By default, tables of bends are searched in the folder the path to which is specified by the SHEETMETAL system variable of KOMPAS-3D.

If the part already contains a table of bends, a dialog box with the following message appears: Selecting another bend table will replace the bend table in the current part. All bends, whose infolding parameter is defined by table, will get new parameter value. Continue? You can cancel or confirm changing the table of bends.

•Click the Overview  button in sheet solid properties setup dialog for the current model.

Changing the table of bends will result in changing properties of all elements of the sheet solid if their flat pattern parameter was taken from the table: the value of this parameter will be selected from a new table. Icons of the changed elements in the Design Tree will be marked with a symbol , indicating the need for the assembly to be rebuilt.

You can write the table of bends stored in the model to a file using the Modelling – Sheet modelling – Bend Table – Save As... command. Specify the file name to be written in a standard Windows dialog box that will appear.

Deleting a Table of bends

To delete a table of bends from the model, use the Modelling – Sheet modelling – Bend Table – Delete command.

After you delete a table of bends from the part, the method for determining the flat pattern length for sheet elements built with the use of the table will automatically change. It will match the type of the table of bends used. The value of the flat pattern parameter will remain equal to the table value for the current radius, bend angle and material thickness.

For example, the element was built with the use of the table of bend amounts. After you delete the table, the Bend Amount method for determining the flat pattern length will be selected for this element. The value of the bend amount will remain equal to the value previously selected from the table.

The model may contain elements with automatically defined bend angles. Such elements include:

•a sheet solid with an open sketch (bend angles are defined by sketch object parameters),

•an incision with the specified size less than minimum (bend angles are calculated using a formula).

If these elements used the table of bends, they will be processed in the following way after the table is deleted.

The method for determining the flat pattern length is automatically changed to a method matching the type of the table used. The flat pattern parameter will take a default value.

If the above sheet elements contain bends that have determination of parameters by source item, then on the screen will appear a bend selection dialog. It contains a list of bends with the described properties and lets you configure processing of these bends if the table is deleted.

In the Bend Selection dialog, specify the bends for which you want to save the flat pattern value obtained from the table. Click OK.

Determination of parameters by source object will be automatically disabled for the selected bends. The method for determining the flat pattern length is automatically changed to a method matching the type of the table used. The flat pattern parameter for each bend will take a value selected from the table based on the angle value of this bend.

The remaining bends will retain determination of parameters by source object. Therefore, each of them will get the same parameters as the source object regardless of the bend angle.