Week 8 - Challenge 2 - Base Bracket Design

AIM:

To Create solid part body of BASE BRACKET from given Class-A surface.

OBJECTIVE:

• Ensure proper tree structure.
• Ensure proper names for every geometrical set according to sketches.
• All sketches should be under the Geometrical set.
• Creating a solid surface using closed surface feature from the given surface.
• Publication of tooling axis,class-A surface,class-B surface,class-C surface.

OPERATIONS INVOLVED:

DRAFT: Draft is amount of taper for molded or cast parts perpendicular to the parting line.

PULLING DIRECTION:The direction from which part is ejected from the mold is called pulling direction. This direction also corresponds to the reference from which the draft faces are defined.

DRAFT ANGLE: A draft angle is angle which is applied to each side of most features of injection moulding part. The angle which is posyioned to run towars the direction of mold's pull an parting line.

NEUTRAL ELEMENT: It is the neutral curve on which the drafted angle will lie. Neutral and parting lines may be same in some cases.

DRAFT ANALYSIS: This command enables you to detect if the oart you drafted will be easily removed . This type of analysis is performed based on colour ranges identifying zones where the deviation frrom the draft direction at any point corresponds to specified values.

TOOLING AXIS: The definiton tab on the tool as dialog this controls how you want tool to orient itself at the same time cutting a multi-axis toolpath. The direction in which mold or core and cavity opens is tooling axis.

CLASS-B SURFACE: These are secondary surfaces that you can see sometimes but are less important these surfaces have tangent continuity and these are created according to Class-A surface.

CLASS-C SURFACE: These are surfaces that are connecting surfaces Class-A,B.

Commands Used:

• Creating new geometrical sets and renaming them
• Point using Circle centre
• Bisecting Line
• Offset Surface
• Extracting the Surface
• Converting the edges by using Intersect 3D lines
• Extrapolating the extracted surface
• Applying the fillets to surface edges
• Trim out the edges which are excess
• Sweep Surface
• Join Surface
• Soldifying the surface body

TOOLING AXIS

Procedure:

Step-1

To import the given class-A surface model in this case Base Bracket model in CATIA V5.

Step-2

Test the boundries in the model.

Step-3

To create tooling axis , first create a dummy axis in the Z-direction by creating a centre point using main hole as reference in the point tool.

Step-4

Now create a plane parallel to point on main hole and YZ plane as reference.

Step-5

Now using the intersect option on the toolbar, select the new plane of the axis system as the first element and class-A surface as the second element. This will give a 2D sketch of Base Bracket viewing from X-direction.

Step-6

Now create lines representing the walls of the Base Bracket using point to point in the line command as shown in below figure.

Step-7

Using the 2lines , create a tooling axis . Create a line that bisects these two lines . This will create a tooling axis as shown below.

DRAFT ANALYSIS(Class-A Surface):

To perform draft analysis on the model: Go to menu bar > Analysis > Feature Draft analysis. to give draft direction use the compass and align Z-axis of it with tooling axis. Once it properly aligned , lock the draft direction. A red point shown on the screen ,select class A-surface and it will show us the current of the model . then go to display tab on draft analysis and select the first option under it colour scale and it will show draft value .set the value to 3 deg under the colour scale variat and press ok.here analysis can be done in two ways quick analysis and full anaysis we choose quick analysis.

Here draft analysis shows

• The Green colour is drafted walls above 3 degree.
• The Red colour is drafted walls above 0 degree.

The analysis shows the drafted walls of Base bracket are above the par of 3deg which is permissible to manfacture in injection modeling.

The Running point analysis hovered along the drafted walls show parts are above 3 and will easily cleared from ejection.

CLASS-B SURFACE CREATION

For creating the class-B surface the required surface have been extracted and then untrimm the surfaces.

Then all the surfaces have been extrapolated to get intersections between them. Likewise we need to repeat the same for all parts of Base Bracket

Since thickness of Base bracket is 2.5mm the B-surface was offset to 2.5mm and the required trim operations must be carried out. and then all parts B-surfaces are joined to form Base bracket B-Surface.

CLASS-C SURFACE CREATION:

The required outer edges of A-Surface were taken by using boundary option.

Then by using the sweep command the surface was created.then by using join command we will join all there edges (2 holes boundaries and outer edge)

Now required C-Surface is formed by trimming edges.

CLOSED SOLID SURFACE:

Now join the class-A and C-surface and check for any open surfaces, now trim these with B-Surface.

Then ,by defining the part body using closed surface command in part design thus solid body is created.

DRAFT ANALYSIS(Solid body):

To perform draft analysis on the model: Go to menu bar > Analysis > Feature Draft analysis. to give draft direction use the compass and align Z-axis of it with tooling axis. Once it properly aligned , lock the draft direction. A red point shown on the screen ,select class A-surface and it will show us the current of the model . then go to display tab on draft analysis and select the first option under it colour scale and it will show draft value .set the value to 3 deg under the colour scale variat and press ok.here analysis can be done in two ways quick analysis and full anaysis we choose quick analysis.

Note: when 3deg draft given to surface sweep of class C Surface edge faces are shown with 2.69 deg draft angle which is not feasible to manfacture then draft given to surface sweep is changed to 3.5deg now the part shows its possible to manfacture.