# SofaKing The Lazy Man Futon by sanmelody

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```									     SofaKing:
The Lazy-Man Futon
Chris Wooldridge
Loren Hankla
Ankur Desai
JT Stukes
Barrett Evans
John Pendley
Agenda
•   Problem Statement
•   Functional Requirements
•   Design Partition
•   Solution
•   Engineering Analysis
•   Prototype
•   Conclusions
•   Questions
Problem Statement
• Futons can be bulky and difficult to adjust
• Create a method to transform the futon
with minimal user effort
• Mechanism must be cost efficient
• Must be able to endure normal everyday
use by an adult
Functional Requirements
•   Single hand operation (maximum of 20 lbs of force)
•   Reliable in terms of life expectancy of design
•   Safely move back and forth without fast moving parts
•   Futon should not hit wall or floor when converting
•   Minimize areas where fingers or clothing may get caught
•   No sharp corners or edges
•   “Lock” mechanisms to prevent accidental shifting
•   Aesthetically pleasing
•   Fairly lightweight
Design Partition
• User Interface: The mechanism the user will

• Sit-up Mechanism: This will transform the futon
from the down position to the up position

• Lay-Down Mechanism: This will transform the
futon from the up position to the down position

• Moving from Wall Mechanism: This will allow
the user to open the futon without having to
move the entire unit away from the wall
Solution: The Lazy-Man Futon
The Lazy-Man Futon
Locking Mechanism: Upright
Locking Mechanism: Down
Total System: Down
Engineering Analysis
Bolt Shear Stress Calc.

Single Shear Equations                                       Double Shear Equations

 ( shear stress )  4 Force /  d 2                          ( shear stress )  2 * Force /  d 2
  4 * (400lbs 6 bolts) /  ( 3 8 inch) 2  604lbs / in 2

SAE Grade 5 bolts – Bolt Shear Strength 120,000 psi
Beam Deflection Calculations
• Frames will be made from 1 inch O.D.
tubing. The thickness of each tube will be
0.3 inches
• Lower Frame will be designed to support
two adult males. Each male is assumed to
weigh less than 200 lbs.
• Maximum beam deflection shall be
calculated and checked
Beam Deflection Calc.

Deflection at Center 
Wa
24EI

3l 2  4a 2   

Wa 2
Deflection at Loads       3l  4a 
6 EI

Deflection Between Loads 
Wa
6 EI

3vl  v   a 2   

E ( Elastic Modulus)  30,000 kpsi  AISI1030 Steel

I       (r24  r14 )      Moment of Inertia for Tubular Beam
4
Summary of Beam Deflection
Torsion Spring Design
• Torsion Spring should require no more
than 20lbs to lower upper rail
• Mattress should not weigh more than 40
lbs. Similar mattress weighed 35 lbs.
• Weight of frame is calculated to be less
than 30 lbs.
• Weight of Individuals shall be supported
by the Locking Mechanism, not the torsion
springs.
Weight of Upper and Lower Frame

Volume of Tube        2
d 2 d12
(        ) in 2
Per Unit Length      4    4
Total Length of Tubing  368 inches
Volume of Tube
Total Volume of Steel                     * Total Length of Tubing
Per Unit Length

Weight Of Frame  Volume of Steel / Density of Steel

Length of Tubing = 328 inches

Density of Steel = 490 lbs / ft 3

Weight of Frame = 40.5 lbs
Torsion Spring Design
• Balance moments about pin connection to
calculate necessary strength of spring
• Minimum spring strength necessary to
prevent back from moving equals 0.8125
(lbs – in/deg). d = Wire size (inches)
D = Mean diameter (inches) Torsion Spring.
4
Ed       N = Number of active coils (front side)
Rt             Rt = Rate of Torsion (Inch-lbs./Rev.)
10 .2 DN
S = Stress (lbs. /sq. inch)
M = Moment (Inch-lbs.)
10.2M
S              P = Load (lbs.)
d3
Range for Spring Constant

Converted:
Minimum Spring Constant – 9.75 (lb-in/deg)
Maximum Spring Constant – 12.0 (lb-in/deg)
Constructing the Prototype
The Lazy-Man Prototype
Spring: Upright and Down
Sliding Mechanism: Drawer Slides
Lazy-Man Futon Videos
Conclusions
• A viable design was for a futon that can easily be adjusted
was created

• SofaKing feels that there is a place in the market for such a
product

• Several additional considerations to the design should be
made in terms of materials
– Bolts appeared to be much stronger than needed
– Metal tubing may be thicker than necessary
– SofaKing feels that there is a place in the market for
such a product
Questions?

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