SofaKing The Lazy Man Futon by sanmelody


The Lazy-Man Futon
     Chris Wooldridge
      Loren Hankla
       Ankur Desai
        JT Stukes
      Barrett Evans
      John Pendley
•   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
  access to adjust the futon

• 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 
                                   3l 2  4a 2   

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

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

E ( Elastic Modulus)  30,000 kpsi  AISI1030 Steel
I       (r24  r14 )      Moment of Inertia for Tubular Beam
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
 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
Loading of Upper Frame
        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.
         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.)
  S              P = Load (lbs.)
    Range for Spring Constant

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
• 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

• 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

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