Week 8 - Challenge 4 - Bumper

REPORT :

INTRODUCTION

A bumper is a structure attached to or integrated with the front and rear ends of a automobile, to absorb impact in a minor collision, ideally minimizing repair costs.

They are designed to absorb impact onto the front and rear of vehicles and minimize low-speed collision damage. Today, standard passenger's vehicle bumpers have a rigid reinforcing bar under the outer cover, with sections of compressible foam or plastic underneath.

A bumper is made up of four parts:

• Bumper cover.
• bumper absorber.
• bumper reinforcement bar.
• bumper mounting system.

The first car bumpers were created in 1901 and consisted of metal beams attached to the front and rear of the car to protect it during a low-speed collision. Designed to protect the expensive and fragile components like the headlights, tail lights, hood, exhaust, and cooling systems, early metal bumpers were focused on sheer resilience.

Modern consumer production cars have almost completely switched over to plastic bumpers. Modern car bumpers are made from thermoplastic olefins, a blend of plastic molecules, rubber, and a reinforcing filler like carbon fiber or calcium carbonate. This blend of materials creates a scratch and impact-resistant plastic that can bond with a wide range of paints and finishes, making it ideal for vehicle bumpers.

Plastic is the preferred material for modern car bumpers for several reasons. First and foremost, plastic is much lighter and more aerodynamic than metal, which improves the car's fuel efficiency. Plastic is also easier to shape, which is useful during both the manufacturing and bumper repair process.

Bumpers of most modern automobiles have been made of a combination of polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) called PC/ABS.

DRAFT ANALYSIS :

The Draft allows the part to easily eject from the mold. The draft angle is to reduce friction between the core, cavity and part and it also avoid the damages. The minimum draft angle is 0.5 degree and the most common draft angle used in the plastic design is 3 degrees.

In CATIA the draft analysis is performed based on colour ranges identifying zones on the analysed element where the deviation from the draft direction at any point, corresponds to specified values.

DESIGN METHODOLOGY

Skin data will be provided to us by the styling team.

Class-A surface means aesthetic surface. It gives the aesthetic of the component which is created by the styling team and gives to the part design engineer to create the part with all engineering aspects.

The first step is to check the continuity of the class A surface. This is to ensure that there is no gap between surfaces. If we find any then we should fix that first.

Analyse the class A surface through visual inspection.

To make sure that the given surface has no gap in between them. We can check it also with the help of Join or boundary commands.

STEPS :

• For plastic parts the Nominal draft angle is 3deg, but even 7deg is allowed for the subassemblies like ribs and slots
• INSERT - ANALYSIS - FEATURE DRAFT ANALYSIS
• First the compass is moved to the part (the compass sholud be placed on the tooling axis) which used to define the new current draft direction, then lock the draft direction using the lock icon
• The colour chart indicates the various condition of the draft angle . the green colour indicates that the part passes and the and can be used for the further operations
• By using the analysis under the running point icon we can check draft angle at the various surfaces of the component
• There are two modes in the Draft analysis quick mode and fully detailed mode .

TOOLING AXIS :

Tooling direction is the main element that to be consider while designing a plastic component. In moulding machine the arrangement is given to open the mould along the direction. It is the direction in which the core and cavity opens.

• First the connectivity between the surfaces to be checked, by using the join option see how the surface is connected and ensure that there are no surface gaps in between the component.
• The other method to check connectivity is using the boundary option. By Extracting and disassemble the boundary of the class – A surface we can check visually gaps between the surface.
• Insert an axis system ensure that is not in current.
• An intersection sketch is made using the ZX plane and the class a surface

By using the point – point line option extend the line along the sketch. With the bisecting line option selecting the two line the TOOLING CLEARING X DIRECTION is created

TOOLING AXIS CREATION IN BISECTING METHOD

• First, the given styling surface was imported into CATIA and checked for irregularities by using Join, Boundary and Disassemble option.
• By using the boundary option the boundary of the hole was created and the centre point was marked.
• Then a dummy tooling axis was created with the centre point in the z-direction.
• By using the axis system the intersection curves were created over the xz plane and then the sides were extended by using point to point line then by using bisecting lines the tooling axis in X direction was created.
• Then by using zy plane the intersection curves were created as shown below and the same procedure was followed for creating the tooling axis in the Y direction.
• Bisecting lines were used to get the exact medium from the two sides so that maximum positive draft angle can be achieved.
• Finally by using the bisecting line option the tooling axis were created by selecting the tooling axis x direction and y direction axis.