Challenge

Week 9 - Attachment Feature Creation - Challenge 2

SCREW BOSS AND DOG HOUSE DESIGN ON COIN HOLDER

AIM- Create the screw boss and dog house for the centre console coin holder considering the design rules

GENERAL RULES FOR SCREW BOSSES

Draft of 0.5 degrees on walls of boss
Thickness is 40% of the nominal wall at the base
Height to diameter ratio- 3:1
Fillet radius of max 0.25
Doghouse wall thickness at the intersection of the part wall C should be 40% or less than the main wall stock T Height of B should be between 3-6 mm

SCREW BOSS

It is used in many parts designed for attachments and assembly.
It helps to screw two different components.
It helps to screw two different components.
It exerts different types of forces - tension, compression, torsion, and shear.
Avoid the bosses that merge into sidewalls because they can form thick section that leads to sink.

SCREW BOSS DESIGN

Screw boss can be on B surface or it can be on a dog house in this we are mounting it on the dog house.
Draw a circular sketch inside a circle of dia 5mm and for the outer circle wall should be 0.6*T on one side so outside dia =2*(0.6*2.5)+5(inside dia)=8mm
Pad it with main tooling direction considering height to dia ratio of 3:1

Draft to ribs of 0.5 degrees. Do union trim with screw boss. Assemble to coin holder main body

Dog House:-

Dog-House is the Engineering supporting feature used in Plastic Designing.
It helps to avoid sink marks.
It also provides enough strength to join different surfaces having a large distance between them.

DOG HOUSE DESIGN

Extract the base of Class A surface and offset it will part thickness as 2.5mm
Sketch a rectangle that should be open from one side for the dog house.
Using sweep with tooling direction and draft it at an angle of 1.5 degrees for the outer surface
Close the upper surface face by offsetting the below-extracted surface and then after trimming it

Convert the dog house surface into the thickened surface by applying a part thickness of 2 mm

Now for the inside faces of the dog house, we need a side core tooling axis created in the Z direction Give a draft to the inside surface of 0.5 degree

Now to create the C and B sections as shown in the design rules, offset the base surface between 3 to 6mm
Extrapolate the surface to achieve the desired length
Switch to the part workbench and split the C and b sections with the thickening part
Again provide a draft to the inside surface as shown Give radius/fillet to inside as 0.4*T = 0.4*2.5 =1mm and for outer edges give fillet as inside radius + part thickness And minimum fillet of 0.5 mm
Assemble with coin holder main body

DRAFT ANALYSIS OF DOG HOUSE

TREE STRUCTURE

FRONT VIEW

TOP VIEW

SIDE VIEW

ISOMETRIC VIEW

Ship work like this
in your own course.