Week 9 - Project 1 - Door Trim Lower with Engineering Features

                                        Door Trim Lower with Engineering Features

Objective: The main aim of this challenge is to create a solid body of 'Door Trim Lower' with the help of the closed surface method by using the 'Generative shape design' workbench in CATIA V5. Performing the 'Draft Analysis' on the solid part body of the Door trim.

Given sample design

Overview:
Initially, we need to offset the given Door Trim class A surface in the inner direction to the required thickness (here the thickness is 2.5mm). After that, we need to close the patches on the offset surface of the bumper, the patches are formed due to the fillets on the Class A surface. Once all the patches are closed properly join them together to make a proper class B surface and now sweep the boundary of the class  A surface to trim with the class B surface to make a closed body. By using the closed body command in the Prat workbench we can get the solid body from the closed surface of the Door Trim. Now, I created the Heat stakes and Locators by considering all the design parameters. After creating all the B-side features on the solid part body of the door trim, I performed a draft analysis for it to check whether all the surfaces are drafted properly or not (The draft angle for the plastic component is 0.5deg to 3deg).

TOOLING AXIS:

To create the tooling axis, I extracted a surface from class A and created a point in the middle of the surface by using the point command and created a line at that point through the x-axis. Now, I performed a draft analysis check from that line whether the created tooling axis is in the correct position or not. If in the draft, analysis check the surface highlighted with green colour on both sides of the surface the tooling axis is in the correct position and direction. 

Tooling axis:

DRAFT ANALYSIS FOR CLASS A SURFACE:

We do perform the draft analysis check for class A surface before we make solid and creation of B-side features. Initially I align the compass to the tooling axis and I gave a 3deg draft angle for the green colour in the colour bar. If the surface is highlighted in green colour the draft angle is given properly for class A surface. If the class A surface is not highlighted fully in green colour, that might be the reason for the draft angle of the class A surface.

CLASS B SURFACE:

To create the class B surface, offset the class A surface inside as per our thickness requirement (here the thickness is 2.5mm, so I offset the class A to 2.5mm inside). Once the offset is created, we can observe some patches on the offset surface by taking the boundary for the offset surface, those patches are formed due to the fillets on the class A surface. We need to cover those patches with the help of the multi-section surfaces command by extracting the patch boundaries. Once all the patches on the offset are covered properly join all the patches with the offset surface, to get the replicated surface of the class A surface. 

CLASS C SURFACE:

I used the sweep command to create the class C surface concerning the boundary of the class A surface. Initially, I extracted the boundary of the class A surface with tangent continuity, and I sweep the extracted boundary concerning the surface at 93deg (for draft angle) for 4mm to intersect properly with the class B surface. Once we sweep all the surface boundaries of class A, extrapolate the sweeped surfaces until both surfaces got intersect properly, and trim them to remove extended extrapolated surfaces to get a proper sweep boundary throughout the entire surface, including the centre hole of the door trim. Now, join both class A and sweep boundary to get the complete class C surface. 

PART BODY:

To create the solid part body from the closed surface, I used the closed surface command in the part workbench.

DESIGN OF HEAT STAKES WITH RIBS :

I took a gemoetrical set and i had drawn a sketch with reference of plane and projection point, after i given PAD for the sketch with in the dimension limits as, with NEUTRAL FIBER.

I had given a DRAFT = 0.5, and given a fillet on the locators side,

DOOR TRIM LOWER WITH HEAT STAKES AND LOCATORS :

Heat stakes :-

Heat staking also known as thermoplastic staking is the process of joining two dissimilar materials together. In heat staking we use local heating and cooling to raise the temperature of plastic components and allow plastic reforming to be carried out.

       

 

 

 

DOG HOUSE

Dog house is an engineering feature used in plastic trim design. Dog houses are used as supporting feature. Sometimes other engineering features like snaps; locators etc. are mounded on them to increase their strength. Dog houses are subjected to draft analysis to prevent breakage of the component during ejection from mould cavity. Dog house and other engineering components are built on B-surface.

GUIDE LINES OF DOG HOUSE

 

C- is where doghouse contacts back side of surface.

Dog house wall thickness at intersection of partwaqll(c) should be 40% or less than main wall stock(T).

Height of (B) should be between 3-6mm.

dog house draft outer faces -1.5 degree

dog house inner face draft-0.5-1 degree

Coring or sink mark cut 3-6mm

height of the dog house is 60mm

dog house outside fillets -3.5mm

dog house inside fillet- 1mm

 

FINAL COMPONENT :

 

 

CONCLUSION :

This project imparted a great deal of knowledge regarding the creation of tooling axis and performing proper draft analysis on a component which are essential steps to ensure a design is fit for manufacture. It also provided valuable insights on the design of a plastic component using Class A, B and C surfaces using CATIA.