A pillar Design with Master Section

OBJECTIVE: To create the A-Pillar's Plastic component from the given Class A Surface using the Master Section that is provided while following all the design rules.

 

 

INTRODUCTION:

Types of Pillars and their Importance in the Automotive Industry:-

 

These pillars standing at the vertical or near-vertical (slightly inclined) position are structural supports for the car's roof and window areas. 

They are pretty important as they provide a strong foundation to install the glass (windscreens, rear, and side windows) of your car. Also, these are strong enough to hold the entire roof (even with roof racking to carry additional weights).

There are several pillars your car can have, and each has got a name. Pillars are named “A”, “B”, “C”, or “D” (in larger vehicles), if you move from the front to the rear end of your vehicle.

The number of pillars will vary from car to car.

For example, most sedans and hatchbacks will have three (A, B & C) pillars whereas larger cars like SUVs will have all four (A, B, C & D) pillars.

Hardtop structures (often referred to as pillarless hardtops) will have only two (A & C) pillars.

 

ROLE OF THE A-PILLAR:

A-Pillar is located on either side of your car’s front window (or windshield).

They also hold the hinges of your front doors. A-pillars are normally made of steel alloys.

Besides being a supporting member, A-pillars are very crucial as far as safety is concerned. A-pillars usually carry a significant amount of load during a frontal collision or a rollover crash. So the larger the width or cross-section, the greater would be the strength but A-pillars always block the driver’s vision (create blind spots) to some extent that can be realized while driving. So, having that said, using thicker A-pillars can make the situation even worst. It might further lower the driver’s vision and raise a question about the vehicle’s and passenger’s safety.

Hence, the design of A-pillars must be optimized giving equal importance to both strength and the driver’s vision.

 

Firstly, we have to create the required Tooling-Axis for the given Class A Surface while meeting the requirements of the necessary Draft Angle & then perform the Draft-Analysis Operation on the Class A Surface itself.

After that, we have to create the required Class B & Class C Surfaces using which we have to make the Final Plastic Component and perform Draft Analysis on it.

 

MAIN REPORT:

Types of Surfaces and their importance for an Automotive Plastic Designer:

• Class A Surface: Class A is an aesthetic surface with the highest quality finish. Most Class A Surfaces for an Automotive Component are made using 'Autodesk-Alias' based on the final Concept-Sketch. All Class A surfaces should have 'Curvature-Continuity', meaning the continuity between the surfaces should share the same boundary. It is taken as a reference by the Automotive Plastic Designer to create 'Class B' and 'Class C' Surfaces.

 

• Class B Surface: The Class B Surface resides below the Class A Surface at a certain thickness. It is created using Engineering Principles that consist of all the necessary features such as Ribs, Bosses, Snaps, etc. This surface isn't visible to the observer from the outside.

 

• Class C Surface: The Class C Surface is the surface created between the Class A and Class B surfaces to join them with each other.

 

Now, we will begin by checking the State of Connectivity for the Class A Surface and ensure that there are no gaps between the surfaces as all the surfaces should be joined well together with each other and shouldn't consist of any discontinuities between them.

Our Class A Surface:

 

There are two methods to inspect the State of Connectivity for the Class A Surface:

1. Using the 'Join' Command' from the 'Operations Toolbar': 

First, we'll click on 'Join Command' and select our Class A Surface. Then, we have to ensure that the 'Check Connexity' option is marked as shown in the images below. It will check for any gaps that may be present between our surfaces. Then, we'll click on the 'Preview' button and if it doesn't show any 'Connexity Error' on our surface then it means our surface is well-connected and there are no discontinuities between it.

In our case, there are no 'Connexity Errors' for the given Class A Surface.

In case there is a 'Connexity Error', we can fix it by increasing the 'Merging-Distance' up to 0.003mm following the industry standard.

 

2. Using the 'Boundary' Command' from the Operations Toolbar:

In this case, we have to click on the 'Boundary' command and then select the Class-A Surface. After that, we'll click on the 'Preview' button to highlight all the boundaries that are on the Class-A surface and check if there are any internal boundaries other than the outer edge boundaries. 

In our case, there is only one boundary present on the Class-A Surface which is the Outer-Edge Boundary and hence we can conclude that all the surfaces are well connected. 

 

CLASS A SURFACE WITH MASTER SECTIONS:

 

PROCEDURE TO CREATE THE MAIN TOOLING AXIS:

Since we have a Master Section provided to us using which we have to create the desired A-Pillar Plastic Component, We'll use that Master Section by extracting the lines as shown below and create a Bisecting Line with respect to those extracted lines to create our Main Tooling Axis.

 

DRAFT ANALYSIS ON THE CLASS A SURFACE:

Next, We will perform a Draft Analysis on the Class A Surface itself:

Before starting with a Draft Analysis Operation, we will go to the 'Customize View Parameters' option under the 'View Toolbar'. Then we will enter the 'Customize View Mode' where we will go under the 'Mesh' option and select 'Material' and press 'OK'. 

To start the Draft Analysis in the 'Generative Surface Design Workbench', we will go to 'Insert' and then look for the option called 'Analysis'. Once found, we will go under that and click on 'Feature Draft Analysis. This will open the 'Draft Analysis' Dialogue box. There, we will ensure that under 'Mode'  we have selected 'Quick Analysis', under 'Display' we will select 'Show or Hide the Color Scale' and then select '3 Degrees' as the permissible draft angle. Then, under 'Direction' we will choose the icon with the symbol of the compass on it which stands for 'Use the Compass to define the new current draft direction'.

It is evident from the above image that the Draft-Analysis on our Class A Surface was successful and the component is feasible to manufacture.

At the region shown below the draft angle is lower than 3 degrees but only by a small amount. 

 

We can communicate this development with the Class A Surface Designer and request them to recreate this region so that it'll clear properly with the Main Tooling Axis but for now we're going to continue with this Class A Surface. 

 

PROCEDURE TO CREATE THE CLASS B SURFACE:

We'll offset the Class A Surface by 2.5mm as shown below:

It is not offsetting properly due to the complexity of the curvature of the Class A Surface and hence we have to recreate that missing patch using tools such as Sweep Command as shown below.

We'll create two boundaries as shown below so that we can use the sweep command on it:

We'll create it using Reference Surface in the Sweep Command's Dialogue Box as shown below:

 

Then, we'll join the newly created surface with the main offset obtained from the Class A Surface.

 Hence, our Class B Surface is created. 

 

PROCEDURE TO CREATE THE CLASS C SURFACE:

To create the Class C surface firstly we have to unhide the Class A Surface and extract it's boundaries as shown below:

We're going to smoothen these extracted boundaries using 'Curve Smooth'. Then we're going to use the 'Sweep' command with 'Reference Surface' & 'With Draft Direction' to create the Class C Surface as shown below:

 

Now, we're going to join the Class A and Class C surfaces with each other. 

Then, we going to trim it with the Class B surface. To ensure that it will be feasible to trim the Class B surface with the joint surface of Class A & C, we're going to extrapolate the Class B surface by a small amount to obtain the closed body as shown below:

 

 

DRAFT ANALYSIS FOR THE CLOSED BODY USING THE MAIN TOOLING AXIS:

 

 

 

PROCEDURE TO CREATE THE ENGINEERING FEATURE- DOGHOUSE USING THE MASTER SECTION:-

Using the Master Section we can create a sketch that can be extruded to create the doghouse's walls as shown below:

 

 

 

Using the Multi-Sections Surface command we're going to create the rear wall of the doghouse as shown below:

 

 

 Then, we'll join them all together and move on to the Part Workbench to thicken it by 2.5mm  as shown below:

 

After that, we're going to provide all the required drafts using the 'Draft Angle' command in Part Workbench. 

Draft Angle is provided at both the outer and inner sections of the doghouse with respect to the Main Tooling axis and Side-Core axis respectively. 

Then, using the Master Section, we're going to create the inner walls of the doghouse as shown below:

We've to provide the draft to these walls with respect to the Side-Core axis as shown below:

We'll also provide the Edge-Fillet as found in the Master Section with a radius of 1.5mm as shown below:

 

 

PROCEDURE TO PERFORM THE CORING OPERATION:

Firstly, we'll create a Multi-Section Surface that will be the base section of the Doghouse as shown below:

 

Then, we'll extrapolate it using Point Continuity and then offset it by 4mm as shown below:

After that, we'll extract the inside walls of the doghouse using the extract command and trim it with the offseted surface as shown below:

Now, we'll offset this surface by 0.708mm because we need a 1mm width for the walls of the doghouse to avoid sink mark formations and the current width is 1,708mm. 

We'll offset it and then extrapolate it so that we can carry out the split operation easily as shown below:

Hence, our coring operation is successful and the engineering feature is now ready to be manufactured. 

 

Now, we're going to conduct a Draft-Analysis on the Engineering Feature to check if it is clearing the draft with respect to both axes and is feasible to manufacture or not.

From the above image, it is evident that the doghouse is clearing along the Main Tooling Axis. 

In the Draft-Analysis,

Green Colour stands for regions where the Draft Angle is more than 0.5 degrees,

Blue Colour stands for regions where the Draft Angle is between 0-0.5 degrees, &

Red Colour stands for regions where the Draft Angle is lower than 0 degrees

It is evident from the above images that the Draft Analysis is successful and the A-Pillar with the Doghouse is feasible to manufacture.

 

Finally, using the Boolean Operation,  we're going to add the Doghouse to the Closed Body of the A-Pillar as shown below:

 

 

3D VIEWS OF THE FINAL PART WITH PROPER COLOR CODE OF THE DRAFT ANGLE IN VARIOUS ORIENTATIONS:

1. FRONT VIEW:

 

 2. TOP VIEW:

 

 3. ISOMETRIC VIEW:

 

 

 

TREE STRUCTURE:

1. CLASS A SURFACE: 

 

2. MAIN TOOLING AXIS AND SIDE-CORE AXIS:

 

3. MASTER SECTIONS:

 

 

4. CLASS B SURFACE:

    

 

5. CLASS C SURFACE:

   

 

6. JOIN & TRIM OPERATIONS:

   

 

 

 7. ENGINEERING FEATURE: DOGHOUSE

 

CORING OPERATION IN THE DOGHOUSE:

   

 

 8. PART WORKBENCH:

 

 

9. DRAFT ANALYSIS AND PUBLICATION: