Challenge

Week 9 - Attachment Feature Creation - Challenge 2

SShobhit Nautiyal8 Jun 2022

DESIGNING OF BOSS AND DOGHOUSE FOR THE CENTRE CONSOLE COIN HOLDER

OBJECTIVES

To create side main tooling axis and side core tooling axis for the centre console coin holder.
To create boss and doghouse on the outer bottom wall of the coin holder.
To do draft analysis of the coin holder along with boss and doghouse using both main tooling and side core tooling axis.

INTRODUCTION

SCREW BOSS: Boss find uses in many part design as points for attachment and assembly, most commonly used variety consists cyclindrical projections with holes designed to receive screws, threaded inserts or other types of fastening hardware. As a rule of thumb the outside diameter of bosses should remain within 2 to 2.4 times the outside diameter of the screw or insert.

DOG HOUSE: The primary function of the doghouse is to avoid sink marks caused due to thick cross sections of the screw boss.

Apart from that it also serves engineering purposes such as if we need a mating point at a height of 100mm from the class B surface, in that case we can first create a doghouse of height of 80mm and then put the screw boss on the top of it.

It is also very helpful in case we need to create the screw boss perpendicular to the tooling axis, in such case we can't attach the screw boss directly to the class B surface because it would lead to sink marks, so here also we can create a doghouse parallel to the tooling axis and put screw boss on it perpendicularly.

DESIGNING METHODOLOGY

CREATION OF SIDE CORE TOOLING AXIS

Extract the base wall of the coin holder and untrim it
create a point on the surface using "on the surface" option and keep the distance zero.
Create a line using "point direction" option and keep the direction along the Y axis.
The resulting line is the side core tooling axis of the coin holder.

CREATION OF SCREW BOSS

DESIGNING RULES FOR BOSSES:

Draft - 0.5 degrees on walls of boss
Thickness- Typically 40% of nominal wall at base.
Height to diameter ratio - 3:1
Radii - 0.25mm of maximum radii.
Boss gussets must meet rib guidlines.

Need to plan ahead for type of ejection.

If less than 25mm tall, draft is not required when sleeve ejection is used.
Over 25 mm tall, draft is required on the outer walls only if sleeve ejection is used.
If sleeve ejection is not used draft is required on all the walls.

CREATION OF DOGHOUSE

DESIGNING RULES FOR DOGHOUSE:

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 3.0 – 6.0 mm.