Week 9 - Attachment Feature Creation - Challenge 2
Aim:-
- To create the attachment features screw boss and dog house on the coin holder using the given design rule.
Objective:-
- To design a screw boss by applying all design constraints.
- To design a dog house by applying all design constraints.
- To perform draft analysis.
Screw boss design rule:-
1. Thickness(W):
Screw boss thickness should be 0.4 or 0.5 times the wall thickness.very thin results in poor mold filing ability.
W=0.4*t mm
In case the outer diameter of boss is 2.4 times screw diameter used.
2. Fillet radius:
Optimal fillet radius is 0.25 mm.
3. Height:
Height to diameter ratio taken is 3:1 for steel whereas the nominal ratio 2:1. it can project up to 0.3 times wall thickness of component.
4. Draft:
The minimum draft for boss walls is 0.5 degree.
Screw boss design:-
1.Importing the coin holder component into CATIA interface.
2.Sketch the boss profile in the base surface.
3.Insert a new body.
4.Pad the profile and thicken it.
From design rule ,
- I am choosing a M6 bolt ,its major diameter will be 6mm.tap drill size would be approximately 5.5mm.
Outer diameter (D)=2.4*d
=2.4*5.5
=13.2mm
5.Change the extruded height to 15mm.
6.Draft is given of about 0.5 degree.
7.All the edges are given 0.25mm maximum fillet radius.
8.Now we can create ribs on bosses to stiffen it.
9.Extract the surface on which the bo is to be design.
10.Draw a line and extrude it to create a surface.
11. Insert a new body.
12.Thicken the surface by 1mm.
From design rule,
W=0.4*t
=0.4*2.5
=1mm.
13.Change the extruded height to 12.5mm.
H=5*t
=5*2.5
=12.5mm.
14.Draft is given of about 0.5 degree.
- The minimum draft angle for boss is +/- 0.5 degree.
- All the edeges should be 0.25 mm fillet radius.
- As per 3:1 ratio.
Height/width =3/1.
Width=12.5/3.
Width=4.166= 5mm.
Views:-
Front view:
Top view:
Side view:
Isometric view:
Intersection of screw boss:-
Dog house design:-
1.Importing the coin holder component into CATIA interface.
2.Sketch a 20*20 square profilein the base surface.
3.Do surface extrude on it. the minimum specified height is 6mm ,we can take 21mm.
4.Extract the base surface ,untrim it ,extrapolate and offset it by 20mm.
5.Use trim command.
6.Insert a body.
7.Thicken it.
The thickness at the junction B surface and dog house should be 0.4*t.
W=0.4*t
=0.4*2.5
=1mm.
But we take 2mm.
6.Extract the wall which is opposite to open side ,untrim it ,extrapolate it and offset it by 19mm.
7.Trim the solid body .
8.Draft is given to 1.5 degreealong tooling direction Y and Z.
From design rule,
- The minimum draft angle for boss is +/- 1.5 degree.
- All the edeges should be 0.25 mm fillet radius.
- Now ,we create rib on bosses to stiffen it
- Extract the surface on which the rib is to be design .
- Draw a line and extract it to the surface.
- Insert a new body .
- Thicken by 1mm.
From design rule,
W=0.4*t
=0.4*2.5
=1mm.
9.Change the extruded height to 12.5mm.
H=5*t
=5*2.5
=12.5mm.
10.Draft is given of about 0.5 degree.
- The minimum draft angle for boss is +/- 0.5 degree.
- All the edeges should be 0.25 mm fillet radius.
- As per 3:1 ratio.
Height/width =3/1.
Width=12.5/3.
Width=4.166= 5mm.
Views:-
Front view:
Top view:
Side view:
Isometric view:
Intersection of screw boss:-
Draft analysis:-
Tree diagram:-
Conclusion:-
I sucessfully completed screw boss and dog house design.