AutoForm Hydro

iletisim: [email protected]

ALGHAFORM PAYLASIMIDIR

www.forum.alghaform.com

iletisim: [email protected]

1

6666 AutoFormHydroAutoFormHydroAutoFormHydroAutoFormHydro

AutoFormHydro is an AutoForm Software package for simulation of tube hydroforming processes processes that use internal fluid pressure, acting in conjunction with the movement of axial and radial tools, to form and shape tubular blanks.

In simulations using AutoFormHydro, load application through the fluid medium may be specified by pressure, volume and heightcontrol. In the first variant, pressurecontrol, evolution of pressure during the forming process is specified by the user, and the resulting volumetric change is computed during the analysis. In the second case, volumecontrol, the desired change of volume is specified and the required pressure is calculated. The third variant, heightcontrol, allows the user to define the approximate radial expansion of the tube during the deformation process. The resulting volumetric change and the required pressure are then calculated during the analysis.

Volume and heightcontrol may be used in the early stages of pro-cess design, when pressure history and optimal tool kinematics are as yet unknown.

Pressurecontrol should be used if the user already has a reasonable idea of its evolution during the deformation process (experience, similar processes, similar parts, etc.).

The following tube deformation process components may be simu-lated using AutoFormHydro:

Prebending Annealing Preforming (closing of tools without fluid medium) Hydroforming (Forming with fluid medium)

In the current version, version 3.1, prebending is simulated in a sin-gle time step. This is a stable and efficient way to simulate prebend-ing whereby changes in thickness and material hardening arising from prebending may be computed. However, change in cross sec-tional shape during prebending cannot be established using this singlestep approach.


2

If shape of the tube cross section is important to simulate accurately subsequent forming stages (for example, if the prebent tube does not have the right shape in its cross section, it may not be possible to position it in the hydroforming tools), prebending may be simu-lated using the preforming process step. CAD models of the preb-ending tools components of the complete tool that define the bent shape of the tube are required in this case. The current version does not allow the simulation of rotary prebending operations.

One of the most important features of AutoFormHydro is its userfriendliness and the ease with which simulations may be set up, run and evaluated. As with all other AutoForm Software packages, pre-processing and data input are tailored to the logical needs of the dif-ferent simulation types. Such a userfriendly design of the software allows even the casual/occasional user to set up and run simulations and to thus carry out feasibility assessments reliably, easily and quickly.

This chapter illustrates the application as well as features of the AutoFormHydro software package based on a series of tutorial lessons. Each lesson introduces new software features and high-lights some of the wide variety of application possibilities. It is rec-ommended that the user work through the lessons in the order listed here as this order represents a progression in the complexity of usage and features, and since each lesson assumes familiarity with features illustrated in the previous ones.

In particular, Lesson 1 gives a very detailed description of the steps involved in the preparation and set up of a typical AutoFormHydro simulation, and is ideal for introducing the new user to the software. Special applications are described in detail in subsequent lessons where some familiarity with the software is assumed.


3

Contents of the Workshop AutoFormHydroContents of the Workshop AutoFormHydroContents of the Workshop AutoFormHydroContents of the Workshop AutoFormHydro

Lesson 1Lesson 1Lesson 1Lesson 1 Set up of a Simulation with Linear Pressure HistorySet up of a Simulation with Linear Pressure HistorySet up of a Simulation with Linear Pressure HistorySet up of a Simulation with Linear Pressure History. . . . . . . . . .. . . . . . . . . .. . . . . . . . . .. . . . . . . . . .4444

Creating a new simulation file Importing CADgeometry Specifying upper and lowertools Defining initial tube geometry Setting up process steps Starting the simulation Post processing results of the simulation

Lesson 2Lesson 2Lesson 2Lesson 2 Specification of Axial Tools and their MovementSpecification of Axial Tools and their MovementSpecification of Axial Tools and their MovementSpecification of Axial Tools and their Movement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48484848

Opening an existing simulation file Inserting new tools (axial tools) Modifying the process step hydroforming Starting the simulation Post processing results of the simulation

Lesson 3Lesson 3Lesson 3Lesson 3 Definition of Timedependent Pressure Definition of Timedependent Pressure Definition of Timedependent Pressure Definition of Timedependent Pressure and ToolControland ToolControland ToolControland ToolControl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59595959

Specifying an annealing process step Defining fluid pressure versus time Defining tool movement as a function of time

Lesson 4Lesson 4Lesson 4Lesson 4 Simulation of Hydroforming using a Counterpunch Simulation of Hydroforming using a Counterpunch Simulation of Hydroforming using a Counterpunch Simulation of Hydroforming using a Counterpunch . . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .71717171

Defining geometry of a counterpunch Specifying working direction for counterpunch Specifying fluid pressure versus time Specifying movements (distance versus time) of counter-

punch and axial tools


Lesson 1: Set up of a Simulation with Linear Pressure HistoryLesson 1: Set up of a Simulation with Linear Pressure HistoryLesson 1: Set up of a Simulation with Linear Pressure HistoryLesson 1: Set up of a Simulation with Linear Pressure History

4

6. 16. 16. 16. 1 Lesson 1: Set up of a Simulation with Linear Pressure Lesson 1: Set up of a Simulation with Linear Pressure Lesson 1: Set up of a Simulation with Linear Pressure Lesson 1: Set up of a Simulation with Linear Pressure HistoryHistoryHistoryHistory

As a first step in setting up, running and evaluating an AutoFormHydro simulation, it is necessary to open a new simulation file and to name it appropriately. This simulation file provides the right context, within the AutoFormUser Interface, for importing required data CAD geometries, lines, material data, etc. and for setting up a simu-lation as desired. In the present lesson, tool geometries will be defined on the basis of imported CAD geometries, the initial tube will be defined from its centerline and dia-meter, and a process sequence (comprising prebending, closing and hydroforming steps) will be established, with linear pressure evolution during hydroforming. Following these steps, the simulation may be started up, and simulation results may be evalu-ated/post processed.

Fig. 1.1Fig. 1.1Fig. 1.1Fig. 1.1

Part geometry lesson 1

Import of a CADgeometryImport of a CADgeometryImport of a CADgeometryImport of a CADgeometryStarting up the AutoForm UserInterfaceStarting up the AutoForm UserInterfaceStarting up the AutoForm UserInterfaceStarting up the AutoForm UserInterfaceThe AutoFormUser Interface may be started up either by doubleclicking on the predefined AutoForm icon on the users desktop, or by using the command xaf at the prompt of an open UNIX shell window. The User Interface displays the AutoForm Logo upon start up.



5

Fig. 1.2Fig. 1.2Fig. 1.2Fig. 1.2

AutoFormUser Interface

Creating a new simulation fileCreating a new simulation fileCreating a new simulation fileCreating a new simulation file

User interfaceUser interfaceUser interfaceUser interface File > New ... > New file > File name: hy_lesson_01 > OK

Fig. 1.3Fig. 1.3Fig. 1.3Fig. 1.3

Dialog box: New file

File name: Enter name of *.sim file (without extension) Units: Select units to be used for inputs. Length units

should be the same as used in the CAD system.



6

Geometric error tolerance: Enter value of acceptable chordal deviation error, to be used for meshing (see below). Default value is adapted to the length units selected under Units. Typical values are between 0.05 and 0.1 mm.

NoteNoteNoteNote: An input field, in any of the AutoForm input utilities, that ishighlighted in red indicates that user input is mandatory in therespective field. Upon appropriate user input, these fields turnwhite. Input fields containing software default parameter values arealso displayed in white; the user may modify the parameter valuesin these fields as required.

Importing CADgeometryImporting CADgeometryImporting CADgeometryImporting CADgeometryClicking on the OK button after completing inputs in the New file dialog box starts up the Geometry generator a utility for import-ing and preprocessing surface geometry.

Fig. 1.4Fig. 1.4Fig. 1.4Fig. 1.4

Geometry generator: PreparePreparePreparePrepare page



7

The surfaces representing tool geometry (CADmodel of the tool) need to be imported and used to define tools for the simulation. These surfaces may be imported either from an IGES or from a VDAFSformat file. During the process of importing such files, the AutoFormAutomesher automatically converts (in the background) the analytical surface descriptions into a mesh, and displays the meshed geometry in the main display. The meshed geometry may be examined visually for problems such as untrimmed or overlap-ping surfaces, and/or gaps between surfaces. If such problems do exist, they need to be fixed in the CAD system, and the corrected tool geometry needs to be reexported (in IGES or VDAFSfor-mat), and reimported into the AutoFormUser Interface.

Reading in and meshing the CADmodelReading in and meshing the CADmodelReading in and meshing the CADmodelReading in and meshing the CADmodel

Geometry gen-Geometry gen-Geometry gen-Geometry gen-eratoreratoreratorerator

File > Import ...

The dialog box Import geometry is displayed. Here the format of the geometry file has to be selected. For Lesson 1 the CAD data of the tools is available in IGESformat.

Fig. 1.5Fig. 1.5Fig. 1.5Fig. 1.5

Dialog: Import geometryImport geometryImport geometryImport geometry

Import geometry > Format: IGES > OK

Upon clicking OK, a file browser dialog box (Select a file) opens up from where the user selects the file to be imported.



8

Fig. 1.6Fig. 1.6Fig. 1.6Fig. 1.6

Dialog: Select a fileSelect a fileSelect a fileSelect a file

Select a file > Files: hy_lesson_01_tools.igs > OK

Upon clicking the button OK a new dialog box the AutoFormAutomesher interface opens up.

Fig. 1.7Fig. 1.7Fig. 1.7Fig. 1.7

Dialog box: AutoFormAutomesherAutoFormAutomesherAutoFormAutomesherAutoFormAutomesher interface



9

The quality of mesh created over the tool surfaces in the IGESfor-mat file is controlled by the AutoFormAutomesher parameters listed in the interface.

Parameters:Parameters:Parameters:Parameters: Error tolerance: Determines the chordal deviation error for meshing. This value is taken from the New file input inter-face (default: 0.1; see Fig. 1.3), but may be modified here. If the imported surface geometry has small radii (2 mm or less), this value should be reduced to 0.05.

Max side length: Maximum element side length in flat areas.

Faces:Faces:Faces:Faces: Treat only: Only faces with specified numbers will be meshed.

Exclude: Faces with specified numbers will not be meshed.

Layers:Layers:Layers:Layers: Treat only: Only layers with specified numbers will be meshed.

Exclude: Layers with specified numbers will not be meshed.

Program: afmesh_3.1 > OK

Clicking the OK button starts up automatic mesh generation using the AutoFormAutomesher (afmesh_3.1). Mesh generation typi-cally requires a few seconds. The progress of the mesh generation can be tracked in the output area of the AutoFormAutomesher interface.

Following mesh generation, the meshed geometry is displayed in the main display.

NoteNoteNoteNote: Please refer to Lesson 2 and Lesson 4 of the workshop Auto-Auto-Auto-Auto-FormUser InterfaceFormUser InterfaceFormUser InterfaceFormUser Interface for detailed instructions on controlling the dis-play of geometry in the main display of the AutoFormUserInterface.

No further inputs or actions are required in the Geometry genera-tor, and it may therefore be closed. All further inputs may be defined entirely from within the AutoFormInput generator.

Geometry gen-Geometry gen-Geometry gen-Geometry gen-eratoreratoreratorerator

File > Dismiss



10

Working with the Input generatorWorking with the Input generatorWorking with the Input generatorWorking with the Input generatorStart of the input generatorStart of the input generatorStart of the input generatorStart of the input generator

User interfaceUser interfaceUser interfaceUser interfaceModel > Input generator ...

Upon making the above menu selection, a dialog box appears wherein the type of simulation set up (Incremental, OneStep or Hydro) needs to be selected and the sheet/tube thickness needs to be specified.

Fig. 1.8Fig. 1.8Fig. 1.8Fig. 1.8

Dialog box: Simulation typeSimulation typeSimulation typeSimulation type

Selection of the type of simulationSelection of the type of simulationSelection of the type of simulationSelection of the type of simulation

Simulation type > Simulation type: Hydro

Upon selecting Hydro the dialog changes to the form:

Fig. 1.9Fig. 1.9Fig. 1.9Fig. 1.9

Window: Simulation type HydroSimulation type HydroSimulation type HydroSimulation type Hydro



11

Choice of tube wall thicknessChoice of tube wall thicknessChoice of tube wall thicknessChoice of tube wall thickness

Simulation type > Tube thickness: 1.2 > OK

The Input generator utility (Fig 1.10) opens up. The Input generator is organized into 6 pages with their respective tabs titled as follows: Title, Tools, Tube, Lube, Process and Control. These titles indicate the type of input data to be specified in each page. Further, tab titles highlighted in red indicate that one or more user inputs are required in the corresponding page. Although explicit user input may not be required in pages titled in black, the user is advised to check the correctness of the default input values in these pages before starting a simulation: AutoForm only checks for the presence of parameters in these pages, but NOT for their correctness/appro-priateness for the simulation being set up. It is recommended that the user traverse the pages from left to right completing the required definitions/inputs under each page.

Fig. 1.10Fig. 1.10Fig. 1.10Fig. 1.10

Input generator: TitleTitleTitleTitle page



12

Input generator: TitleInput generator: TitleInput generator: TitleInput generator: TitleUnder Title, the user may include a brief description of the present simulation/product. The content of this box is displayed in the lower left corner of the main window and also appears as an anno-tation on a postscript printout/file output.

TitleTitleTitleTitleTitle: hy_lesson_01 (training, date)

NoteNoteNoteNote: While a brief title consisting of the simulation file name,username and current date is automatically created, this may beedited and modified by the user.

In addition to the Title field, the user may write in a description of the current level of development, material, etc. in the field titled Comments (Fig. 1.10).

Input generator: ToolsInput generator: ToolsInput generator: ToolsInput generator: ToolsTwo types of tools may be specified for an AutoFormHydro simu-lation: Lateral and Axial.

Lateral: Lateral tools work/move laterally to the tube. For example upper and lowerdie, all preforming tools, sliders, counterpressure punch (radial punch) etc.

Axial: Axial tools work/move axially to the tube. Axial punches/counterpunches that are used to facilitate tar-geted material flow in the forming zone may be defined using this option. Only two axial tools can be defined. Axial start at the beginning of the tube and Axial end at the end of the tube.

A page needs to be created under the Tools page for each tool in the simulation. One such page, for the lateral tool (die), is already defined (Fig. 1.11). Tool pages for additional tools need to be cre-ated by the user. In Lesson 1 two lateral tools (upper and lowerdie) have to be defined. Definition and usage of axial tools will be described in Lesson 2.



13

Fig. 1.11Fig. 1.11Fig. 1.11Fig. 1.11

Input generator: ToolsToolsToolsTools page

First the predefined tool die needs to be renamed as upper_die. This is accomplished very easily by clicking the mouse pointer in the input field Name (Fig. 1.11) and typing in the new name.

ToolsToolsToolsTools die > Tool name > Name: upper_die > Enter

The subpage die is thus renamed as upper_die.

Tool geometry must now be defined. This may be carried out by using one of two options: Reference ... and Read f. file ... (Fig 1.11).

Reference: Based on the tool geometry entities already imported (Geometry generator). Currently active meshed faces of the selected imported entity may be assigned to the tool.



14

Read f. file: By reading in tool geometry previously saved to file in AutoFormformat (e.g. tool data from earlier sim-ulations).

ToolsToolsToolsToolsupper_die > Geometry: Reference ...

A new dialog box appears (Fig. 1.12) wherein faces may be selected that may then be defined as the tool geometry. The following are the available options for selecting faces:

Fig. 1.12Fig. 1.12Fig. 1.12Fig. 1.12

Window: Reference tool geometryReference tool geometryReference tool geometryReference tool geometry

Current geometry: The valid geometry is displayed and all further actions refer to this geometry. If more than one geometry is available in the geometry generator the appro-priate one may be selected here.

Pick faces: In the current version of AutoFormHydro, Pick faces is the only available method for identifying geometry (tool surfaces) for subsequent definition.

Activate/Deactivate: Faces may be picked or highlighted using the rightmouse button (or Shift right mouse but-ton). Once picked, these faces may be activated or deacti-vated using the Activate/Deactivate button. If a picked face is already active, it may only deactivated. Conversely, an active face may only be deactivated. Also, it is only pos-sible either to activate or to deactivate a face at a time: it is not possible to activate a few of the picked faces and to simultaneously deactivate others.

Activate all: The button Activate all activates all faces. This option is used to activate the whole model.

Toggle active: The button Toggle active inverts the activa-tion status of the objects in the geometry file: it activates



15

the deactivated objects and deactivates those that are acti-vated.

The faces of the tool upper_die are selected as follows:

To select a face that will be part of the tool to be defined,

click on the desired face with the right mouse button

NoteNoteNoteNote: Several faces can be selected using the ShiftShiftShiftShift right mousebutton combination. This key combination may also be used tocreate a rectangular rubber band which may be used to enclosea set of faces to be selected. Two selection possibilities are avail-able:

Only those faces that lie entirely within the rubber band may beselected, or those faces that are entirely within the rubber bandand those that intersect the rubber band may be selected. It ispossible to toggle between these options as follows: FileFileFileFile > Prefer-Prefer-Prefer-Prefer-encesencesencesences > Select crossingSelect crossingSelect crossingSelect crossing (on or off).

Select the faces which represent the tool to be defined, and activate them, as shown in Fig. 1.13.

Fig. 1.13Fig. 1.13Fig. 1.13Fig. 1.13

Necessary faces for the tool upper_dieupper_dieupper_dieupper_die

Complete the definition of tool geometry, after picking the appro-priate faces, by clicking on OK in the Reference tool geometry dia-log box.

Reference tool geometry > Activate > OKwww.forum.alghaform.com


16

No further inputs are required in this subpage of the Tools page. However a short description of Position and Offset is given here:

Position: Positioning is used to move the tools into correct position prior to start of the simulation. The input fields correspond to the x, y and zcoordinate.

Offset: An input for the offset means that from the new tool an offset is created with the value in this field. Usually it is not necessary to specify any offset for hydroforming.

In the field Working direction the working direction for each tool is defined:

dx dy dz: A vector in x, y and zdirection determines the working direction for the tool.

Move: Movement of the tools in or opposite to working direction is defined here.

ToolsToolsToolsToolsupper_die > Working direction > dx dy dz: 0, 0, 1 > Move: -10

NoteNoteNoteNote: The input for MoveMoveMoveMove must be 10101010 because the tool is movedagainst the working direction.

It is also possible to define the working direction by a start/end pointor by a default curve/line.

Tool stiffness is specified in the Stiffness input field. A stiffness value of approximately 50 is appropriate and should not be changed. When complete, the upper_die tool input page appears as shown in Fig. 1.14.



17

Fig. 1.14Fig. 1.14Fig. 1.14Fig. 1.14

Inputs for the tool upper_dieupper_dieupper_dieupper_die in the page ToolsToolsToolsTools

It is necessary to define another tool (lower_die) for the simulation. To do this, a new subpage has to be created under the Tools page.

ToolsToolsToolsTools Add tool ...

The Add tool (Fig. 1.15) dialog box opens up.Fig. 1.15Fig. 1.15Fig. 1.15Fig. 1.15

Dialog box: Add toolAdd toolAdd toolAdd tool



18

Type of tool: The type of the tool (Lateral or Axial, see above) is defined here.

Default tool settings: Input values, except geometry, of an earlier defined tool can be taken over (Use settings of tool:), or the standard settings (Use default settings) can be selected.

NoteNoteNoteNote: For axial tools (Axial startAxial startAxial startAxial start or Axial endAxial endAxial endAxial end) only standard settingsare available.

Selection of type and settings for the new toolSelection of type and settings for the new toolSelection of type and settings for the new toolSelection of type and settings for the new tool

ToolsToolsToolsToolsAdd tool > Type of tool > Lateral > Use settings of tool: upper_die > Add tool

A new Tools page opens up, with the settings carried over from the tool page upper_die. For this new tool the name, the geometry and the working direction must be defined. The procedure to do so is same as described above.

Settings for the new toolSettings for the new toolSettings for the new toolSettings for the new tool

ToolsToolsToolsToolstool2 > Name: lower_die > Enter

Geometry > Reference ...

Select faces, from the geometry displayed in the main display, by using the Shiftright mouse button combination (Fig. 1.16), and activate the selected ones using the Activate button in the dialog box Reference tool geometry.

Reference tool geometry > Activate > OK

ToolsToolsToolsToolslower_die > Working direction > dx dy dz: 0, 0, 1

NoteNoteNoteNote: Setting for MoveMoveMoveMove (-10-10-10-10) was taken over from tool upper_dieupper_dieupper_dieupper_dieautomatically.



19

Fig. 1.16Fig. 1.16Fig. 1.16Fig. 1.16

Necessary faces for the tool lower_dielower_dielower_dielower_die

After the inputs for the tool lower_die are completed, the subpage for this tool should appear as shown in Fig. 1.17.



20

Fig. 1.17Fig. 1.17Fig. 1.17Fig. 1.17

Inputs for the tool lower_dielower_dielower_dielower_die in the page ToolsToolsToolsTools

All specifications on the page Tools are thus complete for Lesson 1.

Input generator: Input generator: Input generator: Input generator: TubeTubeTubeTubeAll details relating to the tubular blank material are specified on this page (Fig. 1.18).

NoteNoteNoteNote: The designation tube includes all semifinished material withany cross section drawn along a defined axis.

www.forum.alghaform.comwww.forum.alghaform.com


21

Fig. 1.18Fig. 1.18Fig. 1.18Fig. 1.18

Input generator: TubeTubeTubeTube page

Three dimensional geometry of the tube axis needs to be specified first.

If a prebent tube is used during hydroforming, the axis of this prebent tube needs to be defined here. This specification is essential even if prebending of the tube is to be simulated using Prebending as the first process step.

NoteNoteNoteNote: The prebent tube axis must be present as a curve. Bendinformation such as axis and radius of bend may not be used here.

There are different ways to define the tube axis:

Input: Contour of tube axis is created using the Curve edi-tor.

Import: The tube axis is specified directly by import from a CAD file.



22

Copy from: The tube axis is specified as a copy of an exist-ing curve. This curve can be selected from curves listed in the Curve manager. These curves may have been imported into the Curve manager from a CADfile, or they may have been already generated in AutoForm.

NoteNoteNoteNote: After definition of the tube axis the button labeled InputInputInputInputchanges to read EditEditEditEdit. Now tube axis can be edited using the Curveeditor.

To specify the tube axis an existing curve from a CAD file is selected.

Import of a tube axisImport of a tube axisImport of a tube axisImport of a tube axis

TubeTubeTubeTubeAxis > Import ...

The dialog box Import line(s) (Fig. 1.19) appears. Here the format of the file to be imported has to be selected. For Lesson 1, the CAD data of the tube axis has been saved in IGESformat

Fig. 1.19Fig. 1.19Fig. 1.19Fig. 1.19

Dialog box: Import line(s)Import line(s)Import line(s)Import line(s)

Import line(s) > Format: IGES > OK

The oftenencountered dialog box Select a file opens up, and the IGESfile for the tube axis can be selected.

Select a file > Files: > hy_lesson_01_axis.igs > OK

Upon clicking the button OK the AutoFormAutomesher interface appears. No further inputs have to be specified, and the mesher afmesh_3.1 is started by clicking OK.

Program: afmesh_3.1 > OKwww.forum.alghaform.com


23

After completion of meshing the dialog box Select curve (Fig. 1.20) appears. Here all meshed curves are listed, and the appropriate one may be selected for the definition of the tube axis.

Fig. 1.20Fig. 1.20Fig. 1.20Fig. 1.20

Dialog: Select curveSelect curveSelect curveSelect curve

Select curve > Curve 1 > OK

NoteNoteNoteNote: It is also possible to select one or more curves in the main dis-play with the right mouse button.

Tube cross section needs to be specified next. Similar to the defini-tion of tube axis, there are several input modes to specify tube cross section.

Additionally circular cross section may be defined using the button Circle. Here the outer diameter may be specified. (Fig. 1.21).

Fig. 1.21Fig. 1.21Fig. 1.21Fig. 1.21

Dialog: Cross section - CircleCross section - CircleCross section - CircleCross section - Circle

TubeTubeTubeTube Cross section > Circle ... > Cross section - Circle > Outer diameter: 58 > OK

NoteNoteNoteNote: Always the socalled neutral fiber has to be defined for thecross section, except the definition of the cross section by CircleCircleCircleCircle. Inthis case the outer diameter will be automatically converted to theneutral fiber.



24

It is possible to influence the position of the cross section relative to the tube axis. This can be done using the field Cross section:

Axis pos: Input boxes may be used to specify the position of the tube axis relative to the center of the cross section defined. If these boxes are empty, or if both boxes have the value 0, the tube axis is positioned to pass through the cen-ter of the cross section. If a x and/or yvalue is input, the tube axis is positioned accordingly with respect to the cen-ter of the cross section of the tube.

Ref X: This option is useful only if the cross section is non-circular. The cross section can be rotated around the tube axis by the specification of a vector.

For Lesson 1, it is not necessary to define either Axis pos, or Ref X.. Here it is possible to move the position of the tube in x, y and/or zdirection.

In the field Properties, material properties of the tube must be specified.

Thickness: Thickness of the tube wall. Although this value is specified when starting up the Input generator, it may be modified here.

Material: The user may select an appropriate preexisting material data file from the available material database (Import), or set up the material data by specifying all of the required material properties (Input). Either way, the speci-fied material characteristics may be reviewed by clicking on the View button.

Rolling direction: Here the rolling direction of the tube needs to be specified. The rolling direction may be either Axial or Circumferential.

Definition of thickness and the material of the tubeDefinition of thickness and the material of the tubeDefinition of thickness and the material of the tubeDefinition of thickness and the material of the tube

TubeTubeTubeTubeProperties > Thickness: 1.2 > Material: FeP04_1 > Rolling direc-tion: Axial

After the inputs for the tube are finished the page tube should appear as shown in Fig. 1.22.



25

Fig. 1.22Fig. 1.22Fig. 1.22Fig. 1.22

Inputs for the tube on the TubeTubeTubeTube page

Input generator: LubeInput generator: LubeInput generator: LubeInput generator: LubeOn this page a coefficient of friction for all defined tools is specified (Fig. 1.23):

Constant: Friction is specified with a constant coefficient for all defined tools. It is possible to select predefined val-ues with the buttons Special lubrication, Standard and Clean. If User defined is selected, an input is necessary.

Table: It is possible to define different coefficients of fric-tion for each tool.

NoteNoteNoteNote: Predefined/default values may be modified in the file Auto-Form.cfg, located in the AutoForm software installation directory.



26

Fig. 1.23Fig. 1.23Fig. 1.23Fig. 1.23

Input generator: LubeLubeLubeLube page

Definition of the coefficient of frictionDefinition of the coefficient of frictionDefinition of the coefficient of frictionDefinition of the coefficient of friction

LubeLubeLubeLubeLubrication > Constant > Constant: User defined: 0.1

The completed Lube page should appear as shown in Fig. 1.23.

Input generator: ProcessInput generator: ProcessInput generator: ProcessInput generator: ProcessThe process step hydroforming is predefined on the page Process as standard.



27

Fig. 1.24Fig. 1.24Fig. 1.24Fig. 1.24

Input generator: ProcessProcessProcessProcess page

For the present simulation, additional process steps must be defined. Therefore it is necessary to add process subpages under the page Process.

ProcessProcessProcessProcess Add process step ...

The dialog Add process step appears (Fig. 1.25)



28

Fig. 1.25Fig. 1.25Fig. 1.25Fig. 1.25

Dialog: Add process stepAdd process stepAdd process stepAdd process step

There are three different types of process steps in AutoFormHydro:

Prebending: This type is used to simulate prebending pro-cesses.

Forming: All forming processes, except the prebending, may be simulated using this type of process.

Annealing: Using this type, an annealing process step may be defined.

NoteNoteNoteNote: The appearance of a new process subpage depends uponthe type of process selected to be specified. In some cases, nouser inputs are required beyond selection of that process type.

Selection of process step PrebendingSelection of process step PrebendingSelection of process step PrebendingSelection of process step Prebending

Add process step > Type of process step: Prebending

The dialog Add process step changes its appearance (Fig. 1.26)



29

Fig. 1.26Fig. 1.26Fig. 1.26Fig. 1.26

Dialog: Add process stepAdd process stepAdd process stepAdd process step, Type: PrebendingPrebendingPrebendingPrebending

Further inputs cannot be specified in this dialog. Preforming may be simulated only as the first step and can only be defined once at the beginning of a simulation.

With Add process step a new process step subpage will be added under the page Process. The name of this new process step may be changed; also, it is possible to define if the start (Start locked) or the end (End locked) of the tube should be locked when simulating prebending.

NoteNoteNoteNote: Prebending of the tube is simulated in this process step in asingle increment. This process step allows the computation of thick-ness and hardening distribution only, and not changes in the tubecross section.

For Lesson 1 predefined/default inputs are used. The page for the Prebending should now appear as shown in Fig. 1.27.



30

Fig. 1.27Fig. 1.27Fig. 1.27Fig. 1.27

Inputs for PrebendingPrebendingPrebendingPrebending on the ProcessProcessProcessProcess page

A new process step has to be defined for closing the tools.

ProcessProcessProcessProcessAdd process step ... > Add process step > Type of process step: Forming

Dialog Add process step looks as shown in Fig. 1.28.



31

Fig. 1.28Fig. 1.28Fig. 1.28Fig. 1.28

Dialog box: Add process stepAdd process stepAdd process stepAdd process step, Type: FormingFormingFormingForming

For this type of process step it is possible to specify further inputs in the dialog Add process step:

Forming step default settings: The settings of a previ-ously defined process step (Use settings of forming step:) may be taken over, or standard defaults (Use default set-tings) can be selected.

Insert position: In this field the position of the new process step is determined. One of the existing process steps has to be identified. After this, it is necessary to specify whether the new process step should be inserted before (Insert before) or inserted after (Insert after) the selected process step.

Further inputs in the dialog box Add process step (see Fig. 1.28):

Add process step > Use default settings > Insert before > hydroforming > Add process step

A new subpage (hydroforming2) is added under the page Process. The following inputs need to be specified here:

Name: In this field the name of the process step must be entered.

Type: The process step Forming has the following sub-types:



32

Preforming: Used to simulate preform operations (except for prebending) or the closing of the tools without fluid medium. This is the default for the process step Forming.

Hydroforming: The hydroforming process (forming with fluid medium) may also be defined here. There are differ-ent ways of specifying a hydroforming process step, as will be explained during the description of the process step Hydroforming.

NoteNoteNoteNote: The subpage changes its appearance depending on thetype of the process step FormingFormingFormingForming selected.

Inputs for the new process stepInputs for the new process stepInputs for the new process stepInputs for the new process step

ProcessProcessProcessProcesshydroforming2 > Process step > Name: closing > Type: Preforming

The subpage for this process step should look like shown below:

Fig. 1.29Fig. 1.29Fig. 1.29Fig. 1.29

Inputs for the process step FormingFormingFormingForming on the page ProcessProcessProcessProcess



33

Further specifications refers to the tool control and the defaults for time:

Tool Control: All defined tools are listed (in case not all tools are shown, the button Show all must be pressed in/turned on). Three control mode possibilities are available for each tool.

Non-active: Tool is not used during this process step. Stationary: Tool is active but stationary during this process

step. Displcmnt: Tool moves during this process step. A veloc-

ity needs to be specified for this tool. Duration: Here the duration of the process step is speci-

fied. Until time: The time measured from start of simulation

until completion of this process step. Until closure: Time needed to close two tools against one

another is established automatically based on contact between these tools.

During time: The time measured from start of this pro-cess step until completion of this process step.

Following inputs for tool and timecontrol should be taken speci-fied:

ProcessProcessProcessProcess closing > Tool control > upper_die > Control mode: Displcmnt > Forming step - tool setup > Velocity: 1 > Setlower_die > Control mode: Displcmnt > Forming step - tool setup > Velocity: 1 > Set

Duration > During time > Time: 10

NoteNoteNoteNote: The duration of the process step depends on the distance ofthe tools and the selected velocity. With a distance of 20 mmbetween upper and lowerdie, and a specified velocity of 1 forboth tools, the duration of movement of both tools towards oneanother is 10 s.

The subpage for the process step closing should appear as shown in Fig. 1.30 upon completion of inputs.



34

Fig. 1.30Fig. 1.30Fig. 1.30Fig. 1.30

Inputs for closingclosingclosingclosing under the page ProcessProcessProcessProcess

Hydroforming is defined as the last process step. When opening the input generator a process step hydroforming is already predefined, and must be modified for this lesson.

The type of this forming process step is hydroforming (see above). This process type offers the following options to control of load (fluid pressure) evolution:

Pressurecontrol: The evolution of pressure is specified. Volumecontrol: The desired change of volume is speci-

fied and the required pressure evolution is calculated dur-ing the simulation.

Heightcontrol: The approximate radial expansion of the tube has to be defined. The required pressure evolution is calculated during the simulation.



35

NoteNoteNoteNote: This process subpages appearance depends on theselected load control method. Inputs specific to the load controloption chosen need to be provided.

In this lesson hydroforming will be done using an increasing pres-sure during the process. This option (Hydroforming, Pressure) is predefined for the type Hydroforming.

Further inputs for tool and pressure control as well as the specifica-tion of the time must be completed.

ProcessProcessProcessProcess hydroforming > Tool control > Show all > upper_die > Control mode: Stationary > lower_die > Control mode: Stationary

Inputs for the process of pressure must be specified in the field Hydroforming. Clicking on the button No pressure starts up the dialog box Pressure (Fig. 1.31).

Fig. 1.31Fig. 1.31Fig. 1.31Fig. 1.31

Dialog box: PressurePressurePressurePressure

For pressurecontrolled processes, there are two ways to define pressure:

End p: The end pressure has to be specified. Time variable: The increase of pressure is defined as

dependent on time.

NoteNoteNoteNote: Pressure inputs are made in N/mm. Options available in thisdialog box depend on the particular pressure input mode chosen(End pEnd pEnd pEnd p, Time variableTime variableTime variableTime variable), and may require additional inputs.



36

In this lesson the end pressure (at end of process step) is specified. Use of the time variable pressure option is described in Lesson 3.

Pressure > End p > Value: 70 > Set

Time input also needs to be completed as follows:

ProcessProcessProcessProcesshydroforming > Duration > During time > Time: 70

The subpage for the process step hydroforming should appear as shown in Fig. 1.32 upon completion of all above inputs.

Fig 1.32Fig 1.32Fig 1.32Fig 1.32

Inputs for hydroforminghydroforminghydroforminghydroforming on the page ProcessProcessProcessProcess

This completes the input of process parameters and description for this simulation. Inputs under the Control page are reviewed below.



37

Input generator: ControlInput generator: ControlInput generator: ControlInput generator: Control

Fig. 1.33Fig. 1.33Fig. 1.33Fig. 1.33

Input generator: ControlControlControlControl page

Inputs on this page (Fig. 1.33) may be numerical (Main), or may be a selection of result variables (Rslts).

Default settings may be used over for Lesson 1 except for the fol-lowing changes.

ControlControlControlControl Main > Restart/post output > WriteRestart (switch off)

Rslts > Contact results > Contact distance above (switch on)

All necessary inputs are now complete, and the simulation may be started, after savings the inputs.

The simulation will be saved under the name that was entered in the dialog box New file. The Save as option may be used to save the



38

inputs to a file with a different name. The user may save the input data from time to time to avoid loss of data in the event of crash of the workstation, loss of power, etc.

Input generatorInput generatorInput generatorInput generatorFile > Save

Job > Start simulation/View log

The window Start job appears (Fig. 1.34).

Fig. 1.34Fig. 1.34Fig. 1.34Fig. 1.34

Window: Start jobStart jobStart jobStart job

Only one simulation may run at any time. Additional simulations may be set up and queued using the Queue option at the bottom of the Start job window. These additional simulations may be added either to the end or start of the current queue.

The simulation can be started by clicking on the button Start.

Start job > Program: afhydro_3.1 > Start

Computed results are appended progressively to the input data geometry, process parameters, control parameters saved in the



39

simulation file specified in the New file input box. Currently avail-able simulation results may be viewed at any time after starting the simulation by reopening the simulation file (File > Reopen) in main display.

After the entire simulation is completed, the window Start job should be closed using the Dismiss button.

Analysis of resultsAnalysis of resultsAnalysis of resultsAnalysis of resultsIn the following the analysis of the most important result variables will be discussed.

Open the *.sim file after the solver finished the calculation.

User interfaceUser interfaceUser interfaceUser interface File > Reopen

Go to the end of the computed simulation:

User interfaceUser interfaceUser interfaceUser interface Time > hydroforming

NoteNoteNoteNote: This can also be achieved with the combination of keys CtrlCtrlCtrlCtrl EEEE.

There are different ways to display result variable:

Using icons: A subset of the computed results (Thickness, Thinning, ...) may be displayed by using corresponding icons displayed on the right side of the main window (Fig. 1.35).

Results menu: All selected result variable are listed under Result variables in the Results menu (Fig. 136).

Fig. 1.35Fig. 1.35Fig. 1.35Fig. 1.35

Icons for the result variables



40

Fig. 1.36Fig. 1.36Fig. 1.36Fig. 1.36

Result variablesResult variablesResult variablesResult variables pulldown menu

FormabilityFormabilityFormabilityFormabilityThe result variable Formability displays the strain state at different locations on the formed tube/sheet (based on the Forming Limit Diagram FLD), and gives the user an overall picture of formabil-ity. Different colors are used to denote the following qualitative types of strain states.

Cracks: Areas of cracks. These areas are above the Forming Limit Curve (FLC) of the material used.

Excess. Thinning: In these areas thinning is higher than the acceptable thinning level (default value for steel 30%).

Risk of cracks: These areas may crack. By default this area is within a 20% zone below the FLC.

Safe: All areas which have no defects wrinkles, thinning or cracks.

Insuff. Stretching: Areas which do not have enough strain (default 2%).

Wrinkling tendency: Areas where wrinkles might appear. In these areas the material has compressive stress but no compressive strain.

Wrinkles: Areas where wrinkles can be expected, depend-ing on geometry curvature, thickness and tool contact. Material in these areas has compressive strains.



41

Display of the result variable FormabilityDisplay of the result variable FormabilityDisplay of the result variable FormabilityDisplay of the result variable Formability

User interfaceUser interfaceUser interfaceUser interface Results > Result variables ... > Formability > Dismiss

or

Select icon Formability.

Display of the result variable Formability in the main display (Fig. 1.37).

Fig. 1.37Fig. 1.37Fig. 1.37Fig. 1.37

Display of the result variable FormabilityFormabilityFormabilityFormability in the main display

In this example cracks can be expected on one side of the dome. On the opposite side, there exists the risk of cracks (Fig. 1.37).

The defaultvalues of result variable Formability can be changed in the following menu:



42

User interfaceUser interfaceUser interfaceUser interfaceResults > Formability ...

Fig. 1.38Fig. 1.38Fig. 1.38Fig. 1.38

Dialog: AutoForm - FormabilityAutoForm - FormabilityAutoForm - FormabilityAutoForm - Formability

The small plot shows the different strain regions/states with respect to the FLC.

ThinningThinningThinningThinningAnother result variable that is often used is the percentage thinning of the material (Thinning).

Display of the result variable Thinning in the main display:

User interfaceUser interfaceUser interfaceUser interfaceResults > Result variables ... > Thinning > Dismiss

or

Select icon Thinning.



43

Display of the result variable Thinning in the main display (Fig. 1.39).

Fig. 1.39Fig. 1.39Fig. 1.39Fig. 1.39

Display of the result variable ThinningThinningThinningThinning in the main display

A scale is displayed in the lower part of the main window with a range of 30% thinning (-0.3) to 10% thickening (0.1) colored from yellow to green (depending on the use color settings). The exact thinning level at any location on the formed tube/sheet may be dis-played by clicking at that location on the tube/sheet (in the main display) using the right mouse button. Esc removes the labels from the display.

To find the maximum thinning and the maximum thickening of the part use the following options:

User interfaceUser interfaceUser interfaceUser interface Results > Show maxResults > Show min



44

Fig. 1.40Fig. 1.40Fig. 1.40Fig. 1.40

Display of the result variable ThinningThinningThinningThinning with min and max values in the main display

NoteNoteNoteNote: The labels for maxmaxmaxmax and minminminmin cannot be removed with the keyEscEscEscEsc. They have to be switched off by using Results > Show maxResults > Show maxResults > Show maxResults > Show max andResults > Show minResults > Show minResults > Show minResults > Show min as toggle switches.

To analyze the areas with high values for thinning the range of the Thinning scale must be changed.

User interfaceUser interfaceUser interfaceUser interfaceResults > Ranges ...

The dialog AutoForm Min/Max Editor appears.



45

Fig. 1.41Fig. 1.41Fig. 1.41Fig. 1.41

Dialog: AutoForm Min/Max EditorAutoForm Min/Max EditorAutoForm Min/Max EditorAutoForm Min/Max Editor

NoteNoteNoteNote: The AutoForm - Min/Max EditorAutoForm - Min/Max EditorAutoForm - Min/Max EditorAutoForm - Min/Max Editor may also be accessed fromthe ResultsResultsResultsResults menu in the user interface: Results > Result variables:Results > Result variables:Results > Result variables:Results > Result variables:RangesRangesRangesRanges.

Min/Max Simulation: Use min and max values of the whole simulation.

Min/Max Increment: Use min and max values of the cur-rent increment.

Simulation default: Use default min and max values. Manual: Use user defined min and max values.

Change the values for the scale manually:

AutoForm Min/Max Editor > Manual > Min.: -0.4 > Max.: -0.2 > Return > Dismiss

Display should correspond to Fig. 1.42. All areas with less than 20% thinning are displayed in green (depending on the chosen color set-tings).



46

Fig. 1.42Fig. 1.42Fig. 1.42Fig. 1.42

Display of the result value ThinningThinningThinningThinning with min value 0.40.40.40.4 and max value 0.20.20.20.2.

Contact distance aboveContact distance aboveContact distance aboveContact distance aboveWith this result variable the distance of each element to the surfaces of the tools is displayed. Thus it is possible to check if the tube is formed out at the end of the simulation, i.e. if it has contact to the tool everywhere.

If this is not the case, the pressure must be increased or the radii have to be increased.

User interfaceUser interfaceUser interfaceUser interfaceResults > Result variables ... > Contact distance above > Dismiss

The range of the scale may be modified to obtain a more meaningful display:

User interfaceUser interfaceUser interfaceUser interfaceResults > Ranges ... > Manual > Min.: 0 > Max.: 1 > Return > Dis-miss

The display should correspond to Fig. 1.43.



47

Fig. 1.43Fig. 1.43Fig. 1.43Fig. 1.43

Display of the result value Contact distance aboveContact distance aboveContact distance aboveContact distance above with min value 0 0 0 0 and max value 1111

You can see that the part is not formed out completely in the area of the dome, in particular at the radii in this region.

Simulation predicts cracks in the area of the dome when using the load control method specified here. In Lesson 2, it will be attempted to prevent splitting by trying to push material into the forming zone.


Lesson 2: Specification of Axial Tools and their MovementLesson 2: Specification of Axial Tools and their MovementLesson 2: Specification of Axial Tools and their MovementLesson 2: Specification of Axial Tools and their Movement

48

6. 26. 26. 26. 2 Lesson 2: Specification of Axial Tools and their Move-Lesson 2: Specification of Axial Tools and their Move-Lesson 2: Specification of Axial Tools and their Move-Lesson 2: Specification of Axial Tools and their Move-ment ment ment ment

Building on the simulation from Lesson 1, we show in this chapter how to improve the result (cracks within the area of the dome).

For this, the existing simulation from Lesson 1 is read in. Since the formability within the area of the dome is exhausted and results in cracks, to afterpush over tried directed material into the transformation zone. This is implemented by axial tools ( slide gate valves), which are to be defined as new tools. In the hydroforming process step, these redefined axial tools must be considered and the axial tool movement should be determined.

During the following analysis we see that the results (among other things regarding the cracks) could be improved substantially (Fig. 2,1).

Fig. 2.1Fig. 2.1Fig. 2.1Fig. 2.1

Calculated part lesson 2

Read in a simulationRead in a simulationRead in a simulationRead in a simulationFor this example, an existing simulation is used and modified as required. For this a prepared *.sim file is available, which is based on Lesson 1.

User interfaceUser interfaceUser interfaceUser interfaceFile > Open

The dialog opens with Select a file (Fig. 2.2).



49

Fig. 2.2Fig. 2.2Fig. 2.2Fig. 2.2

Dialog: Select a fileSelect a fileSelect a fileSelect a file

Select the following sim file in the dialog Select a file:

Files: hy_lesson_02.sim > OK

The geometry from Lesson 1 is shown in the main window and the input generator for a Hydro simulation is opened.



50

Fig. 2.3Fig. 2.3Fig. 2.3Fig. 2.3

Geometry in the user interface

Some modifications in the input generator must be made now.

Modifications in the Input generatorModifications in the Input generatorModifications in the Input generatorModifications in the Input generatorInput generator: TitleInput generator: TitleInput generator: TitleInput generator: TitleThe title for the new simulation can be modified.


After this, you can continue to work on the Tools page.

Input generator: ToolsInput generator: ToolsInput generator: ToolsInput generator: ToolsHere the axial tools must be defined, with which the material is to be moved directly into the transformation zone.

As mentioned in Lesson 1, only an axial tool can used for the start of tubing, Axial start, and an axial tool at the tube end, Axial end has to be defined.

NoteNoteNoteNote: The axial tools are created automatically. It is not possible inthe present version to define your own geometry for the axial tools.



51

Create the axial punch:

ToolsToolsToolsTools Add tool ... > Add tool > Axial start > Use default setting > Add tool

A new tool was defined of the type Axial start. Now, the name must be modified:

tool3 > Tool name > Name: axial_start > Enter

Further specification are not required here.

NoteNoteNoteNote: The working direction is set to standard by default. This work-ing direction is then the direction (curved) of the tubing axle. Inaddition, it is possible to define for the working direction a vector(dx dy dzdx dy dzdx dy dzdx dy dz).

The second axial tool is similarly created:

ToolsToolsToolsTools Add tool ... > Add tool > Axial end > Use default setting > Add tool > tool4 > Tool name > Name: axial_end > Enter

Thus, the axial tools are defined. Further specification must be only given now on the Process page.

Input generator: ProcessInput generator: ProcessInput generator: ProcessInput generator: ProcessOn the Process page, only the process step hydroforming has to be redefined and must be selected.

The redefined axial tools are set by default to Non active and must be all inserted with Show.

First, the tool control for axial_start is defined:

ProcessProcessProcessProcess hydrofoming > Tool control > axial_start > Control mode: Displc-mnt



52

The dialog Forming step - tool setup appears, in which a constant rate (Constant velocity) or a shift in dependency of the time (Time variable displacement) for the axial tool can be selected for axial_start (Fig. 2.4).

Fig. 2.4Fig. 2.4Fig. 2.4Fig. 2.4

Dialog: Forming Step tool setupForming Step tool setupForming Step tool setupForming Step tool setup

NoteNoteNoteNote: In order to check for which axial end the tool attacks b, thistool can be displayed in the main window, by clicking on the but-ton named axial_startaxial_startaxial_startaxial_start on the bottom right in the main window. Thisapplies similarly to all other tools.

Define the velocity for the axial tool axial_start:

Forming Step - tool setup > Constant velocity > Value: 0.01 > Set

NoteNoteNoteNote: Option Time variable displacement is explained in lesson 3.

Thus the control inputs of the tool axial_start are completed. Now the specification for the tool axial_end will be defined:

ProcessProcessProcessProcesshydrofoming > Tool control > axial_end > Control mode: Displcmnt > Forming Step tool setup > Constant velocity > Value: 0.1 > Set

Thus the specification on the Process page is finished.



53

The page for the process step hydroforming should look as in Fig. 2.5 now.

Fig. 2.5Fig. 2.5Fig. 2.5Fig. 2.5

Specification for hydroforminghydroforminghydroforminghydroforming on the ProcessProcessProcessProcess page

From the Control page, make sure the WriteRestart option is switched off and under Rslts the post variable Contact distance above is switched on

Now the simulation can be started:

Input generatorInput generatorInput generatorInput generator File > SaveJob > Start simulation ... > Start job > Program: afhydro_3.1 > Start

After the calculation is complete, the *.sim file is reopened and the results can be analyzed. Close the Start job window with Dismiss.

User interfaceUser interfaceUser interfaceUser interface File > ReopenTime > hydroforming



54

Analysis of the simulation resultsAnalysis of the simulation resultsAnalysis of the simulation resultsAnalysis of the simulation resultsFormabilityFormabilityFormabilityFormabilityFirst the simulation is examined with the Formability criterion. The post variable is activated by clicking the Formability button on the icons menu located on the right side of the main window (moving the mouse over each icon shows the label).

It is clearly seen that the critical areas of the dome are now no longer at risk of splitting (Fig. 2.6).

Fig. 2.6Fig. 2.6Fig. 2.6Fig. 2.6

Representation of the post variable FormabilityFormabilityFormabilityFormability in the main display



55

ThinningThinningThinningThinningNow the second post variable Thinning will be analyzed. The Icon Thinning is selected.

From the Thinning plot, it is clear that an improvement of the result has been achieved by the axial tool movement (Fig. 2.7).

Fig. 2.7Fig. 2.7Fig. 2.7Fig. 2.7

Representation of the post variable ThinningThinningThinningThinning in the main display

Contact distance aboveContact distance aboveContact distance aboveContact distance aboveThe formingout of the pipe can be checked with the Contact dis-tance above result criteria:

User interfaceUser interfaceUser interfaceUser interface Results > Result variables ... > Contact distance above > Dismiss

Results > Ranges ... > Manual > Min.: 0 > Max.: 1 > Return > Dis-miss



56

The representation in the main display should look as in Fig. 2.8:

Fig. 2.8Fig. 2.8Fig. 2.8Fig. 2.8

Representation of the post variable Contact distance aboveContact distance aboveContact distance aboveContact distance above in the main display

It can be seen that the formingout the pipe has been improved by the axial tool movement. The pipe is almost completely formed out. There are only certain small areas in the dome, which have a small distance of the pipe to the tool surface.

Finally, the Forming Limit Diagram is to be analyzed.

Forming Limit DiagramForming Limit DiagramForming Limit DiagramForming Limit DiagramThe Forming Limit Diagram (FLD) describes the failure of the sheet metal due to cracks. In the FLD the Forming Limit Curve (strain states above those failure/cracks are detected) is represented as a black curve. Into this diagram, all finite elements of a simulation with the two main strain results (major and minor) are shown. So one can judge the robustness of a reforming process also visually in this diagram.



57

This diagram is activated with the following instruction in the main window:

User interfaceUser interfaceUser interfaceUser interface Results > FLD ...

By selecting Show all (on the top right), all the elemental strains are shown in this diagram (Fig. 2.9). In the current example, all strains are situated below the border deformation curve. This indicates that the process is quite safe and robust from a formability standpoint.

Fig. 2.9Fig. 2.9Fig. 2.9Fig. 2.9

Representation of all finite elements in the forming limit diagram at the end of the forming process

It is also possible to plot the colors of the post variable Formability in the forming limit diagram:

AutoForm FLD > Diagram > Formability



58

The representation is then as in Fig. 2.10.

Fig. 2.10Fig. 2.10Fig. 2.10Fig. 2.10

Representation of all finite elements in the forming limit diagram with the colors of the post variable FormabilityFormabilityFormabilityFormability

The window AutoForm - FLD is closed with Dismiss.

The user interface can be closed as follows:

User interfaceUser interfaceUser interfaceUser interfaceFile > Quit or hot keys Ctrl Q


Lesson 3: Definition of Timedependent Pressure and Tool ControlLesson 3: Definition of Timedependent Pressure and Tool ControlLesson 3: Definition of Timedependent Pressure and Tool ControlLesson 3: Definition of Timedependent Pressure and Tool Control

59

6. 36. 36. 36. 3 Lesson 3: Definition of Timedependent Pressure Lesson 3: Definition of Timedependent Pressure Lesson 3: Definition of Timedependent Pressure Lesson 3: Definition of Timedependent Pressure and Tool Controland Tool Controland Tool Controland Tool Control

Tube hydroforming requires numerous process steps for manufacturing: The semi fin-ished tube undergoes prebending, annealing and hydroforming with timevariable pressure increase and axial tool displacement. To achieve this in simulation, it is neces-sary to define lateral and axial tools first. Next, we need to specify prebending and annealing. Finally, it is necessary to add timepressurecontrol and time variable tool movement.

Fig 3.1Fig 3.1Fig 3.1Fig 3.1

Part geometry

Creating a new projectCreating a new projectCreating a new projectCreating a new project

File > New ... > New file > File name: hy_lesson_03 > OK

Meshing and import of CAD geometryMeshing and import of CAD geometryMeshing and import of CAD geometryMeshing and import of CAD geometry

The CAD tool data for this example is provided in IGES format.

Geometry generator > File > Import ... > Import geometry > Format: IGES > OK > Select a file > Files: hy_lesson_03_tools.igs > OK

This opens the meshing dialog:



60

After meshing, the full tool appears in the main display. Close the Geometry generator:

Geometry generator > File > Dismiss

Input generator dataInput generator dataInput generator dataInput generator data

User interfaceUser interfaceUser interfaceUser interfaceModel > Input generator > Simulation type > Hydro

For this example please use an initial wall thickness of 1.2 mm.

Simulation type > Tube thickness: 1.2 > OK

Input generator: TitleInput generator: TitleInput generator: TitleInput generator: Title


Input generator: ToolsInput generator: ToolsInput generator: ToolsInput generator: ToolsIn case the semi tube is not formed by tool closure, it is not neces-sary to define the above and below tools. Only one (closed) tool is sufficient.

Lesson 3 will contain one lateral tool only.

Definition of a lateral tool:

ToolsToolsToolsToolsGeometry > Reference ...

In the main window, select all faces using the right mouse button (Fig. 3.2) and open the Reference tool geometry dialog using Acti-vate.

Reference tool geometry > Activate > OK



61

Fig. 3.2Fig. 3.2Fig. 3.2Fig. 3.2

Faces for the lateral tool

Fig. 3.3Fig. 3.3Fig. 3.3Fig. 3.3

Input for lateral moving tool on ToolsToolsToolsTools page



62

Please use the default settings for tool working direction and stiff-ness (Fig. 3.3).

Definition of axial moving tools:

ToolsToolsToolsToolsAdd tool Add tool > Axial start > Use default setting > Add tool

tool2 > Tool name > Name: axial_start > Enter

Please use the default settings for tool working direction.

The last remaining tool is axial_end. For this definition, follow the procedure described for tool axial_start accordingly.

ToolsToolsToolsToolsAdd tool Add tool > Axial end > Use default setting > Add tool

tool3 > Tool name > Name: axial_end > Enter

Please use the default settings for tool working direction. This com-pletes the entries on Tools page for Lesson 3.

Input generator: TubeInput generator: TubeInput generator: TubeInput generator: Tube

Enter the data for the semi finished tube: Tube centerline, outer tube diameter, material data, etc.

The tube centerline for this lesson is provided in IGESformat which can be imported as follows:

TubeTubeTubeTubeAxis > Import ... Import line (s) > Format: IGES > OK > Select a file > Files: hy_lesson_03_axis.igs > OK


After meshing is complete, select the tube centerline in the main window using the right mouse button (Fig. 3.4).

Select curve > OK



63

Fig. 3.4Fig. 3.4Fig. 3.4Fig. 3.4

Center axis

This example features a circular cross section. Therefore, definition can be achieved using the tube outer diameter.

TubeTubeTubeTube Cross section > Circle ...Cross section - Circle > Outer diameter: 51 > OK



64

Tube position and material (FeP04_1) are according to default val-ues (Fig. 3.5).

Fig. 3.5Fig. 3.5Fig. 3.5Fig. 3.5

Input data on TubeTubeTubeTube page

Input generator: LubeInput generator: LubeInput generator: LubeInput generator: Lube

LubeLubeLubeLubeLubrication > Constant > Constant > User defined: 0.15

Input generator: ProcessInput generator: ProcessInput generator: ProcessInput generator: Process

Next, define process steps prebending, annealing and tube hydro-forming.

PrebendingPrebendingPrebendingPrebendingProcessProcessProcessProcessAdd process step ...

Add process step > Type of process step > Prebending > Add pro-cess step



65

ProcessProcessProcessProcess Prebending > Process Step > Type: Prebending > End locked

AnnealingAnnealingAnnealingAnnealingAfter prebending, define the process step annealing. This stress relieving procedure may be added after each forming process. Annealing provides better material forming capabilities for the main forming process. For calculation purposes, this is achieved by resetting stresses and strains in the part, yet saving the tube thick-ness values. You may also change the material properties during annealing.

Fig. 3.6Fig. 3.6Fig. 3.6Fig. 3.6

Definition of annealing

Initial material: Base material (before annealing) New material: New material data (after annealing)

Upon working with defaultvalues, AutoFormHydro will calcu-late with the rvalues data. Optionally you can choose a material



66

from the AutoForm database or create a user defined material (e. g. via Input on Tube page) or by file import.

View: Displays stressstraincurve, forming limit diagram and materials rvalues.

Import: Import of a material file (*.mat)

Defining the annealing process:

ProcessProcessProcessProcessAdd process step ...Add process step > Type of process step > Annealing > Insert posi-tion > hydroforming > Insert before > Add process step

Please use default values for annealing (Initial material, New mate-rial).

Tube HydroformingTube HydroformingTube HydroformingTube HydroformingThe main, final process step is hydroforming.

ProcessProcessProcessProcesshydroforming > Process step > Type: Hydroforming > PressureTool control > Show all > die > Control mode: Stationary

Axial tool movement (axial_start and axial_end) is described by a function of time and displacement.

hydroforming > axial_start > Control mode: DisplcmntForming step - tool setup > Time variable displacement

Pressing the button Time variable displacement activates the box Time - Displacement - Table in dialog Forming step - tool setup activated.



67

This allows for a definition of tool movement dependent on time.

Fig. 3.7Fig. 3.7Fig. 3.7Fig. 3.7

Dialog: Forming step - tool setup

Add: Allows for definition of data sets (Time - Displace-ment).

From start: The input is defined for beginning of the pro-cess. If the data is not sufficient for the entire process step, the pressure value will be kept constant until end of pro-cess is reached.

From end: If pressure is known at the end of the process, the definition may start from there. Input data in the box will start at the end of the process and calculate backwards.

At end: In this case the pressureline will be used in the defined direction. However, the final value is moved towards the ends of the process step. It may happen that the pressureline is unknown at the beginning. In this case, the first pressure value will be used until timecontrol is activated.

For this lesson please use the following settings in the Forming step - tool setup dialog box:

Time: 0 > Displacement: 0Time: 10 > Displacement: 4 > AddTime: 40 > Displacement: 5 > AddTime: 100 > Displacement: 5 > From start > Set



68

For axial_endtool use data according to tool movement of axial_start.

hydroforming > axial_end > Control mode: DisplcmntForming step - tool setup > Time variable displacement

Time: 0 > Displacement: 0Time: 10 > Displacement: 4 > AddTime: 40 > Displacement: 5 > AddTime: 100 > Displacement: 5 > From start > Set

Finally, enter the time controlled pressure increase.

Documents

AutoForm Hydro