Design of backdoor
Project: Backdoor Design Challenge
Introduction:
This project report is about 3D modelling a Backdoor Assembly of automobile using Siemens NX 11.
Objective:
The aim of this Project is to model a Backdoor Assembly considering all design and safety factors which satisfies industry’s standards, manufacturing & functional requirements and engineering inputs using Siemens NX 11.
Introduction:
Backdoor or also called as tailgate is a hinged door at the rear of a vehicle that can move up or down which allows access to boot space during loading and unloading.
Backdoor assembly is consisting of Inner panel, Outer panel and reinforcements like hinge, gas stay, wiper motor mount and latch reinforcements.
In this project we will design assemble backdoor with respect to the given outer panel skin.
Backdoor Assembly:
Backdoor is a sheet metal assembly consisting inner panel, outer panel, latch and hinge. Outer panel is fixed on the inner panel by using hemming operation which is carried out using rollers rolling the outer panel over the inner panel.
The inner panel provides strength and it helps to dissipate forces in rear collision. It also provides place to attach the latch and hinges and space for routing electric cables for electronic equipment.
The latch and striker are responsible for flush fitting of hood.
The hinge allows hood to swing along its axis which helps to open and close the backdoor.
Design inputs:
Backdoor thickness information
Outer panel thickness = 0.75 mm
Inner panel thickness = 0.75 mm
Reinforcement thickness = 1.5 mm
3D Modelling:
Inner panel:
The inner panel is designed with respect to the provided skin data/surface. The inner panel is important part of backdoor assembly which redirect the forces during rear crash.
Reinforcements:
Reinforcements are provided at hinge mounting, gas stay mounting, striker mounting and wiper motor mounting to increase the strength.
Commands used:
Extracted geometry: Creates a associative copies of bodies, surfaces, curves, points etc.
Offset Surface: This command is used to create a surface by offsetting a set of faces.
Offset Curve in Face: It is used to offset curves along a selected face or surface.
Trim Sheet: It is used to cut off a portion of surface.
Bridge Curves: Creates a tangent blend curve between two objects.
Through curves: Creates a surface through multiple sections where the shape changes to pass through each section.
Through curve mesh: Creates a body through a mesh of sections in one direction and guides in another direction where the shape fits through the mesh of curves.
Swept: Creates a body by sweeping a section along one or more guides using various options to control the shape along the guide.
Studio Surface: Creates a surface using any number of section and guide strings.
Face blend: Add tangent blend faces between selected set of faces with specified radius.
Projected curve: Using this command we can project curves, sketch or points on to the selected face or plane.
Law Extension: It creates a law-controlled extension from base sheet, dynamically or based on laws for distance and angle.
Extend Sheet: Extends the sheet body by distance or to the intersection with another body.
Edge blend: Rounds the sharp edges of the faces with specified radius.
Emboss: This command modifies the surface by projecting a section along a vector, with options for end cap location and shape.
Curve on Surface: It used for sketching a spline on face or surface.
Mirror Geometry: Copies the geometry and mirrors them across a plane.
Sew: Sew is used to combine sheet bodies by sewing their edges together.
Thicken: It gives thickness to the surface body.
Striker and Hinge Assembly:
Latch & striker positioning and orientation is the critical stage in backdoor design.
The positioning done using sketching a circle with center as the axis of the hinge which passes through the center of the striker. The latch striker must be perpendicular to the circle to get the correct orientation of the latch which enables it to close the backdoor perfectly.
Hemming:
Hemming is a forming operation in which the edges of the sheet are folded over another sheet in order to achieve a tight fit.
In the backdoor assembly outer panel is rolled over the inner panel joining it together.
Relief given at front and rear:
Mastic Points:
The mastic seal is a kind of hard rubber glue added between inner and outer panel of hood to join them together at different points called mastic points.
Mastic sealant also helps to reduces noise and vibrations.
Conclusion:
Thus, the backdoor of the car is modeled using the engineering inputs and it satisfies the industrial manufacturing and functional requirements using NX CAD.