sofaking: the lazy-man futon chris wooldridge loren hankla ankur desai jt stukes barrett evans john...
TRANSCRIPT
SofaKing:The Lazy-Man Futon
Chris WooldridgeLoren HanklaAnkur DesaiJT Stukes
Barrett EvansJohn 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
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.
2/4)( dForcestressshear
Single Shear Equations
22 /604)83(/)6400(*4 inlbsinchboltslbs
Double Shear Equations
2/*2)( dForcestressshear
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.
22 4324
alEI
WaCenteratDeflection
alEI
WaLoadsatDeflection 43
6
2
236
avlvEI
WaLoadsBetweenDeflection
SteelAISIkpsiModulusElasticE 1030000,30)(
)(4
41
42 rrI
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 springs.
Weight of Upper and Lower Frame
inchesTubingofLengthTotal 368
TubingofLengthTotalLengthUnitPer
TubeofVolumeSteelofVolumeTotal *
SteelofDensitySteelofVolumeFrameOfWeight /
Length of Tubing = 328 inches
Density of Steel = 490 lbs / ft3
Weight of Frame = 40.5 lbs
22
122 )
44( in
dd
LengthUnitPer
TubeofVolume
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).
DN
EdRt 2.10
4
3
2.10
d
MS
d = Wire size (inches) D = Mean diameter (inches) Torsion Spring.N = Number of active coils (front side) Rt = Rate of Torsion (Inch-lbs./Rev.)
S = Stress (lbs. /sq. inch)
M = Moment (Inch-lbs.)
P = Load (lbs.)
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 VideosLinks:
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?