The default interface of Symmetry/Double Attach is illustrated in Figure 6.1.47(a). The user can select any function in Double Attach to display the interface as shown in Figure 6.1.47(b). In Symmetry function, there are four types of part geometry for the user to input: NO SYMMETRY, SYMMETRY, HALF SYMMETRY INPUT and QUARTER SYMMETRY INPUT. In Double Attach function, there are three types of part geometry for the user to select: LEFT / RIGHT HALF INPUT, LEFT / RIGHT FULL INPUT and TWO PARTS. When using LEFT / RIGHT HALF INPUT, the user should first mirror another same part using Symmetry function, then design the Double Attach.
(a) (b)
Figure 6.1.47 Symmetry / Double Attach
This function allows the user to define a symmetrical die by mirroring a half symmetry or quarter symmetry plane.
Four geometry options are available in the SYMMETRY dialog box. There are described as following:
NO
SYMMETRY (Default)
This is the default option. All other functions provided in the SYSMMETRY dialog box is disabled.
SYMMETRY
The part is defined as 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.
QUARTER SMMETRY INPUT
Only one quarter of the part geometry is available. The function will mirror the other three quarters of the part about two symmetry planes to create a complete part.
There are three types of symmetry options available. There are described as the following:
X-Z 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.
Y-Z 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 or Quarter 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 a DYNAFORM Question dialog box, as
shown in Figure 6.1.48, and highlight the
result from the operation. 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 6.1.48 DYNAFORM Question dialog box
Note: If the symmetry plane is not defined to be die, when clicking on ALIGN NODES, the message window prompts:
DIE NOT DEFINED IN DATABASE
If QUARTER SYMMETRY INPUT is selected, there are two symmetry planes and two symmetry axes. One symmetry axis is vertical to the first and through the base point (first selected point), while the other symmetry axis is vertical to the first plane and through the second symmetry axis.
If HALF SYMMETRY INPUT or QUARTER SYMMETRY 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 UNDO button is used to undo the mirror operation.
The steps needed to define a symmetrical die are listed as the following:
1. Read in the symmetrical geometry, mesh it and assign it as DIE.
2. Select a geometry type, for example, HALF SYMMETRY.
3. Select a symmetry type, for example, X-Z PLANE.
4. Using the SELECT POINT button to select two points to define the symmetry plane and the axis direction.
Figure 6.1.49 Half Symmetry Part With X-Z Plane
5. Click on the MIRROR GEOMETRY SYMMETRY button, following by selecting the part as illustrated in Figure 6.1.49. The mirror result is illustrated in Figure 6.1.50.
Figure 6.1.50 The Mirroring Result
This function allows the user to design Double Attach by entering the part geometry. There are three types of part geometry listed below.
LEFT / RIGHT HALF INPUT
This function allows the user to input one part geometry, then mirror another same part by using Symmetry function. Once this button is selected, the Symmetry interface is activated, as shown in Figure 6.1.51.
Figure 6.1.51 Left / Right Half Input
LEFT
/ RIGHT FULL INPUT
This function allows the user to input two part geometries with the same outline and different interior. Once this button is selected, the Symmetry Type is disabled, but Select buttons for Left and Right are activated, as shown in Figure 6.1.52.
Figure 6.1.52 Left /Right Full Input
TWO PARTS
This function allows the user to input two totally different part geometries. Once this button is selected, the Symmetry Type is disabled, but Select buttons for Left and Right are activated. The interface is similar to the one in Figure 6.1.52.
The user can select LEFT and click on SELECT to select the left part; select RIGHT and click on SELECT to select the right part; or click on AUTO SELECT to select left / right part automatically. After selection of part, the program will auto generate outline between two parts and activate ADJUST BDY-POINT for the user to adjust the location of boundary point. Once the outline is generated, the user can modify the shape of it by using ADD, DELETE and EDIT buttons.
If LEFT / RIGHT HALF INPUT option is selected, the Symmetry Type is activated. After mirroring the part via symmetry function, the program will select left / right part automatically and auto generate outline between two parts, as shown in Figure 6.1.53. Click APPLY to generate region, as illustrated in Figure 6.1.54.
Figure 6.1.53 Generate Outline
Figure 6.1.54 Generate Middle Region
If the generated region needs to be modified, the user can select ADD to add control lines. Click the left mouse button to add landscape control lines, as shown in Figure 6.1.55, and click the right mouse button to add portrait control lines, as shown in Figure 6.1.56. After control lines are added, select a control line in Control Lines list and click on EDIT to edit the control line in the displayed Edit Curve dialog box. The generated region after editing is illustrated in Figure 6.1.57. Refer to Section 5.1.15 Edit Line for detailed description.
Figure 6.1.55 Add Landscape Control Line
Figure 6.1.56 Add Portrait Control Line
Figure 6.1.57 Generated Region after Editing
If the generated region is easy to form undercut or the part boundary is not smooth, the user can first smooth the boundary by OUTER SMOOTH function to avoid undercut or poor quality. Refer to Section 6.1.1.10 OUTER SMOOTH for detailed description.