Creating a Helix Documentation

7/30/2019 Creating a Helix Documentation

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Creating a Helix

This task shows the various methods for creating helical curves, such as coils and springs

for example.

These curves are 3D curves, as opposed to the spirals.

Open the Helix1.CATPart document.

1. ClickHelix .The Helix Curve Definition dialog box appears.

2. Select a starting point.

3. Select an axis.


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4. Set the helix parameters.o Pitch: the distance between two revolutions of the curve

You can define the evolution of the pitch along the helix using a law.

b. ClickLaw... to display the Law Definition dialog box. In thiscase, you need to select a law as defined in Creating Laws.

The 2D viewer enables you to preview the law evolution before applying

it.

The Law Viewer allows you to:

visualize the law evolution and the maximum andminimum values,

navigate into the viewer by panning and zooming(using to the mouse),

trace the law coordinates by using the manipulator,


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change the viewer size by changing the dialog boxsize

reframe on by using the viewer contextual menu change the law evaluation step by using the viewer

contextual menu (from 0.1 (10 evaluations) to 0.001 (1000

evaluations)).

c. Choose type of law to be applied to the pitch.It can stay Constant, or evolve according to a S type law.

For the S type pitch, you need to define a second pitch value. The pitch

distance will vary between these two pitch values, over the specified

number of revolutions.

d. ClickOK to return to the Helix Curve Definition dialog box.o Height: the global height of the helical curve, in the case of a

constant pitch type helix

o Orientation: defines the rotation direction (clockwise or counterclockwise)

o Starting Angle: defines where the helical curve starts, inrelation to the starting point.

This parameter can be set only for the Constant pitch only.

o

Taper Angle: the radius variation from one revolution to theother. It ranges from -90 to 90 excluded.

For a constant radius, set the taper angle to 0.

o Way: defines the taper angle orientation.Inward: the radius decreases

Outward: the radius increases.

o Profile: the curve used to control the helical curve radiusvariation. The radius evolves according to the distance between the axis

and the selected profile (here the orange curve).

Note that the Starting point must be on the profile.


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o

5. ClickReverse Direction to invert the curve direction.6. ClickOK to create the helix.

The helical curve (identified as Helix.xxx) is added to the specification tree.

Parameters can be edited in the 3D geometry. To have further information,

refer to the Editing Parameters chapter.

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Creating Spirals


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This task shows how to create curves in the shape of spirals, that is a in 2D plane, as

opposed to the helical curves.

Open the Spiral1.CATPart document.

1.

ClickSpiral .

The Spiral Curve Definition dialog box appears.

2. Select a supporting plane and the Center point for the spiral.

3. Specify a Reference direction along which the Start radius value ismeasured and from which the angle is computed, when the spiral is defined by an

angle.

The spiral is previewed with the current options:


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4. Specify the Start radius value, that is the distance from the Center point,along the Reference direction, at which the spiral's first revolution starts.

5. Define the spiral's Orientation, that is the rotation direction: clockwise orcounter clockwise.

6. Specify the spiral creation mode, and fill in the corresponding values:o Angle & Radius: the spiral is defined by a given End angle from

the Reference direction and the radius value, the radius being

comprised between the Start and End radius, on the first and last

revolutions respectively (i.e. the last revolution ends on a point which

distance from the center point is the End radius value).

Ref. direction = Z, Start radius = 5mm, Angle = 45,

End radius = 20mm, Revolutions = 5

o Angle & Pitch: the spiral is defined by a given End angle fromthe Reference direction and the pitch, that is the distance betweentwo revolutions of the spiral.


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o Radius & Pitch: the spiral is defined by the End radius valueand the pitch.

The spiral ends when the distance from the center point to the spiral's last

point equals the End radius value.Ref. direction = Z, Start radius = 5mm,

End radius = 20mm, Pitch = 4mm

Ref. direction = Z, Start radius = 5mm, Angle = 45,

Pitch = 4mm, Revolutions = 5

oDepending on the selected creation mode, the End angle, End radius,

Pitch, and Revolutions fields are available or not.

7. ClickOK to create the spiral curve.The curve (identified as Spiral.xxx) is added to the specification tree.

Parameters can be edited in the 3D geometry. To have further information,

refer to the Editing Parameters chapter.

8.


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Creating Laws

This task shows how to create evolution laws within a .CATPart document, to be used

later on when creating Generative Shape Design elements, such as swept surfaces, or

parallel curves.

Open the Law1.CATPart document.

1. ClickLaw .The Law Definition dialog box appears.

2. Select the reference line.3. Select a definition curve.

The law is computed as the distance between points on the reference line and

their matching points onto the curve.

o Laws can be created using negative values.The intersection between the reference line and the definition curve

is taken into account to change the law evaluation sign.

The direction lets allows you to choose which side of the referenceline must be considered as positive.


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o IfX parameter on definition is checked, the Xparameter is displayed on the selected curve and represents the

percentage of the curvilinear abscissa on this curve. The law is

computed by projecting the start point normally onto the reference

line.o You can analyze the law using the manipulator, or specifying

a value in the X field. This parameter represents the percentage of

the curvilinear abscissa on this curve. The law is computed by

projecting the start point normally onto the reference line.

The Y field indicates the distance between any point on the reference

line and its matching point on the selected curve.

4. Define the law amplitude by entering a value or using the graphic manipulators inthe Scaling field.

When the law is applied to a geometric element, the latter usually is not of the

same length as the reference line. Therefore a linear mapping is applied between

the reference line and the element the law is applied to, resulting in a scaling of

the law.

In the illustration, the law is applied to a circular sweep (top) and to a parallel

curve (bottom). The dotted lines represent the linear mapping between the law

(middle) and the two elements to which it is applied.

5. CheckHeterogeneous Law to define the applied law unit (none for ratio law;degree, radian, or grade for angle law) and the distance measure units (current

unit by default).

Two conversions will be performed during the law evaluation:

o conversion from the model unit (millimeters) to the storedmeasure unit

o conversion from the stored applied law unit to the model unit(degrees) in case of an angle


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6. ClickOK to create the law.The law (identified as Law.xxx) is added to the specification tree.

It is now ready for use in the creation of other Shape Design elements.

7. ClickParallel Curve .8. In the Parallel Curve Definition dialog box, clickLaw....9. Select the Law.1 from the specification tree.10.ClickOK.

The law is applied to the selected element.

o When the reference line and definition curve do not present thesame length, only the common area is used to compute the law.


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o CheckBoth Sides to generate a parallel curve symmetrically oneach side of the selected curve.

Note that depending on the geometry, the elements may not appear

symmetrical. They are if the curve is a line, otherwise, the resulting

curves' shape may differ:

Resulting parallel curves

when a line is selected

Resulting parallel curves when any curve is

selected

o When X parameter on definition is deselected, the selectedcurve should not present several intersections with the plane normal to the

reference line. If there are several intersections, the law cannot be

evaluated and cannot be applied when creating geometric elements.

11.Laws created using the Knowledge Advisor product, being mathematical formulas, can

be used with Generative Shape Design's operators, such as swept surfaces, or parallel

curves for instance.

For further information, refer to Creating and Using a Knowledge Advisor Law in

Knowledge Advisor's User's Guide.

Note that laws created using the Law icon of Generative Shape Design product can be

referenced by laws created with Knowledge Advisor product.

Selecting a published law from another part is not allowed.


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Editing Parameters

This task shows all the parameters that appear in green in the 3D geometry when

creating or editing a feature.

This command is available on the following commands:

Operator Type Sub- Type Parameter(s) displayed

Bump Deformation Distance

(Maximum distance along the

deformation direction from the

deformed surface)

Center and

Radius

Radius, Start Angle, End Angle

Center and Point Start Angle, End Angle

Two Points and

Radius

Radius

Bitangent and

Radius

Radius

Circle

Center and

Tangent

Curve as center

element

Radius

Corner Radius

Curve

Parallel

Geodesic parallel

mode

Constant (Offset Distance)

Diabolo Draft Angle

Extrapolate Length Length, Limit Type

Extrude Length 1, Limit 1

Length 2, Limit 2

Helix Taper Angle, Starting Angle

Pitch

Height

Angle/Normal

to Curve

Support and

Geometry on

support selected

Angle

Length (Start and End)

Point-Point Support selected

Point-Direction Support selected

Tangent to

Curve

Mono-tangent and

Support selected

Normal to

Surface

Line

Bisecting Support selected

Length (Start and End)

Infinite Start Point: End

Infinite End Point: Start

Infinite: /

Offset Offset Value

Angle/Normalto Plane

AnglePlane

Offset from Length, Offset Distance


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Plane

Coordinates Length, X, Y, Z coordinates

On Curve Geodesic Length (distance on curve)

On Plane Length, H, V

Point

On Surface Length (distance on surface)

Polyline Radius, Radius at point

Reflect

Line

Angle

Revolve Angle1, Angle2

Rotate Rotation Angle

Shape Fillet Bi-Tangent

Fillet

Radius

Parallel Start Angle, Parallel

End Angle, Meridian StartAngle, Meridian End Angle

Sphere

Radius

Angle and

Radius

Start Radius

End Radius

End Angle

Angle and Pitch Start Radius

Pitch

End Angle

Spiral

Radius andPitch

Start RadiusEnd Radius

Pitch

Explicit Sweep Angle

Two Limits Length1, Length2

With Reference

Surface

Angle, Length1, Length2

With Reference

Curve


Sweep

Linear Sweep

With Draft

Direction


Translate Distance and

Direction

Distance

Create any of the features above.

Let's take an example by performing a rotation.

1. Once you selected the inputs to create the rotated element, clickPreview todisplay the associated parameters in the 3D geometry.


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2. Double-click the angle value in the 3D geometry.The Edit Parameter dialog box appears.

3. Use the spinners to modify the value.The display automatically updates and the object is modified accordingly.

You can modify the angle value using the Angle manipulators.

o To display the parameters' values, you need to click thePreview button. Otherwise, only manipulators are displayed.

o To edit the parameters once the feature is created, select it inthe specification tree, right-clickxxx.1object > Edit

Parameters from the contextual menu.

o If you want the parameters to be kept permanently, check theParameters of features and constraints option in Tools > Options

> Infrastructure > Part Infrastructure > Display.

4.

Creating a Helix Documentation

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