This function allows the user to define a symmetrical die by defining a bilateral symmetry plane.

Three part geometry options are available in the Symmetry dialog box.

 NO SYMMETRY (Default)

This is the default option. All other functions provided in the Symmetry dialog box are disabled.

 SYMMETRY

The part is defined as symmetrical (the part itself is usually symmetrical).

 HALF SYMMETRY INPUT

Only one half of the part geometry is available. The function will mirror the other half of the part about a symmetry plane to create a complete part.

There are three types of symmetry options available. There are described as the following:

XZ-PLANE

The symmetry plane is parallel to the XZ-Plane of the Global Coordinate System. The user must select two points to define the XZ-Plane. The first point is used to define the location of the symmetry plane, while the second point is used to define direction of the axis of symmetry.

YZ-PLANE

The symmetry plane is parallel to the YZ-Plane of the Global Coordinate System. The user must select two points to define the YZ-Plane. The first point is used to define the location of the symmetry plane, while the second point is used to define direction of the axis of symmetry.

TWO-XY-POINT

The symmetry plane is normal to the XY-Plane of the Global Coordinate System. The user must select two points to define the XY-Plane. The first point is used to define the location of the symmetry plane, while the second point is used to define direction of the axis of symmetry.

The user can enter the Shift value and click on  or  to move the symmetry axis. If the nodes at the plane of symmetry are not collinear along the symmetry plane, the Align Nodes function can be utilized to correct the problem.  When the part is defined as Half Symmetry, eta/DYNAFORM will activate the Align Nodes function  The user can define the tolerance input field to align the nodes along the line of symmetry. After clicking on this button, the program will pop up an eta/DYNAFORM Question dialog box, as shown in Figure 7.1.40, and highlight the result from the operation. As illustrated in Figure 7.1.41, the user can select Yes to accept the result or select No to correct the inconsistency between some nodes on symmetry plane and symmetry plane direction within the offset range via adding align nodes by cursor. The user can also select Abort to redefine the offset range.

Figure 7.1.40  eta/DYNAFORM Question dialog box

Figure 7.1.41  Highlight nodes

If Half Symmetry Input is selected, the Mirror Geometry button will be activated. This function allows the user to select elements, which will be mirrored about the symmetry plane(s). The Reset button is used to undo the mirror operation.

The steps needed to define a symmetrical die are listed as follows:

1.       Read in the symmetrical geometry, mesh it and assign it as Die part.

2.       Select a geometry type, for example, Half Symmetry.

3.       Select a symmetry type, for example, Two – X-Y - Points.

4.       Using the Select Point(s) button to select two points to define the symmetry plane and the axis direction.

Figure 7.1.42  Half Symmetry Part with XZ-Plane defined by selecting two points

5.       Click on the Mirror Geometry button. The mirror result is illustrated in Figure 7.1.43.

Figure 7.1.43  The Mirroring Result

Note: Define the part geometry as Symmetry or Half Symmetry Input, if user click other type of part geometry, the eta/DYNAFORM Question dialog box will pop up below.

Figure 7.1.44  eta/DYNAFORM Question dialog box

Yes

Click the Yes button, the part will restore to the status before define as Symmetry or Half Symmetry Input, without saving the tipping operations, delete created boundary fill features, binder and addendum. For Half Symmetry Input geometry, it will delete mirrored half part same time.

No

Click the No button to exit the dialog box with no operation.