Applied Precision Design, LLC
Concept Design Review
BioMedical Orbital Mixer
Amir Torkaman
Applied Precision Design, LLC
1755 East Bayshore Rd. Suite 9B
Redwood City, CA 94063
Phone: (650) 387-7902
Fax: (650) 493-1195
www.AprecisionDesign.com
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
Typical Design Cycle: Biomedical Orbital Mixer
VIDEO
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
Simplified Energy Model: Energy Entering System
CONSERVATION OF ENERGY:
Two Modes of Operation:
1.
Cranking Cycle: Energy In = Energy Stored into System
2.
Operating Cycle: Energy Stored = Work Done By System
L
Energy Internal
Into
energy
System (stored)
Work
Done By
System
T
Energy Into the System:
Energy Into System = Human Power
Work = Τ∆Θ
example: T = 2.25Nm
L = 75mm
∆Θ = 30 Turns X 2Π = 188.4 rad
W = 423.9 J
Independent of Crank Time or Speed (30 sec)
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
Simplified Energy Model: Energy Stored
CONSERVATION OF ENERGY:
L
T
Energy Internal
Into
energy
System
Work
Done By
System
W
K
m
I
Energy Stored in the System:
Total Energy = Potential + Kinetic Energy
Potential = m.g.∆h
Spring = ½ K ∆Θ^2
m = 5 grams (x4)
m = 5 grams (x4)
k ~ 23 N-mm / rad
d = 50mm
g= 9.8 m/sec^2
∆Θ = turns x 2Π
I = 50e-6 Kg/m^2
∆h = 30mm
Spring E = varies with time
Kinetic E = 0.88 J
Potential E = 0.005 J
Kinetic Energy = ½ Iw^2
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
Simplified Energy Model: Energy Leaving System
L
Drag Force =
T
C ~ 0.8
A = .0012 m^2
W
K
m
I
D (drag)
V = 9.4 m/sec
F = .05 N (drag force)
Drag Energy = 363 Joules
F (friction)
Energy Out of the System:
Total Work = Frictional Losses + Drag
Frictional Losses = Σ (ζ.E + μ.N.d.∆Θ)
ζ = 3-5 % (gear efficiency)
μ = 0.2 (sliding bearing friction)
Total Energy Loss ~ 80 Joules
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
Critical Design Parameters
V = r.W
Power In = Work / Time = 1.90 Watts (after frictional losses)
Drag Power =
m
g1
= 2.02 Watts
Centripetal Acceleration = r.W^2 (120g’s)
Drag Power ~ r^3
Acceleration ~ r
Minimize Distance To
Center of Mass (r)
EXPERIMENTS
Air Drag Coefficient < 0.4

Use Rolling Bearing μ < 0.01
Critical Design
Parameters
Increase Air Resistance
(Thru addition of a thin sheet metal foil)
Significant reduction in final velocity

Reduce # of Gears / Belts / &
provide Good Alignment
Increase Mass 5g  10g
(Same max speed / took longer to get to speed

Increase Mass 5g –> 15g
(no change in Steady-State conditions)
Reduce Moving Mass / Inertia
Improve Gear Efficiency
Thru Lubrication ζ < 3%
Amir Torkaman • ENGR10 • Fa13
 vibration and rattling, more force on bearings

Reduce # of Cartridges

Increase of Cartridge Length
Applied Precision Design
Mixer Design

Design Goals
 Top loading
 Cartridge top twist in holder
 Low power loss


Ball bearings
Minimize CG dia.
 Mixer: 2mm orbital diameter
 Centrifuge: 1800 RPM
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
COMPARISON
CONCEPT 1 - CONCEPT 2
CONCEPT 1: Separate Mechanisms
CONCEPT 2: Combined Mixer /
Centrifuge
1.
2.
3.
4.
1.
+ SEPARATE MECHANISMS SIMPLIFY DRIVE
+ EASY ACCESS TO CARTRIDGES
- SEPARATE SHAFT AND SUPPORT
- TWO ENCLOSURES REQUIRED
2.
3.
Amir Torkaman • ENGR10 • Fa13
+ REDUCES OVERALL BOX LENGTH FROM 15.75
TO 14.5
- REQUIRES CLUTCH AND BRAKE TO STOP
MOTION OF SPINNER WHILE MIXING
- INTERFERENCE IF CARTRIDGES ARE NOT
REMOVED FROM NON-USED MECANISM
Applied Precision Design
CONCEPT 1
CONCENTRIC MIXER/SPINNER
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
CONCEPT 1
CONCENTRIC MIXER/SPINNER
PINS IN SLOTS GUIDED IN SLOTS
OF POLYMER BEARING
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
CONCEPT 2
SEPARATE MIXER/SPINNER ASSEMBLY
TOP VIEW
15.75”
9”
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
ECCENTRIC DRIVE
Orbital Mixer Design
ECCENTRIC SHAFT
UPPER BEARINGS
LOWER BEARINGS
TIMING BELT COG
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
Centrifuge Design

Design Goals
 Top loading
 Low power loss







Ball bearings
Minimize CG dia.
Aerodynamic Holders
G1 > 50G
G2 ~ 120G
G-load axial to cartridge
Contain Blood Spill
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
CONCEPT
CONCENTRIC MIXER/SPINNER
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
DETAL DESIGN
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
CONCEPT
SEPARATE MIXER/SPINNER ASSEMBLY
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
Typical Design Cycle: Biomedical Orbital Mixer
VIDEO
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design

BACK UP SLIDES
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
CONCEPT
SEPARATE MIXER/SPINNER ASSEMBLY
FRONT VIEW
7.75”
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
Centrifuge Design

Calculated Cartridge G’s
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
CARTRAGE RETAINER
RIBS ON CARTRAGE PREVENT ROTATION SO THAT CAP CAN BE
TWISTED IN PLACE
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
CONCEPT 1 - ARM WITH PIN IN SLOT PREVENTS ROTATION
DOES NOT YIELS TRUE ORBITAL MOTION.

CARTIRIDGES NEARIST PIN
RESTRICTED IN Y MOVEMENT

CARTRIDGES AWAY FROM PIN
EMPHASIXED IN Y MOVEMENT
PIN IN SLPT
Y
X
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
CONCEPT 2 - SPRING ROTATION PREVENTER
4X SPRING POST
SPRING NOT SHOWN
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
COMPARISON OF MIXER ANTI-ROTATION DEVICES
ARM IN SLOT

- DOES NOT YIELD TRUE ORBITAL MOTION.
1.
2.
CARTIRIDGES NEARIST PIN RESTRICTED IN Y MOVEMENT
CARTRIDGES AWAY FROM PIN EMPHASIXED IN Y MOVEMENT

+ Simple Design

- FRICTION
SPRING

- SPRINGS PRONE TO BREAKAGE
- UNKNOWN HARMONICS
+ LOW FRICTION
- NOT GOOD WITH CAP TWIST

+ Simple Design



SWASH PLATE


+ ROBUST DESIGN
- FRICTION
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
MECHANICAL GOVERNOR WITH SPEED INDICATOR
GOVERNOR
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
MECHANICAL GOVERNOR WITH SPEED INDICATOR
WITHOUT SIGHT
WITH INDICATOR SIGHT
CORRECT SPEED
OVER SPEED
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
ELECTRONIC GOVERNOR
GENERATOR
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
COMPARISON OF GOVERNORS
MECHANICAL GOVERNOR
1.
2.
3.
4.
- MULTIPLE MOVING PARTS
- DIFICULT TO CALIBRATE
- INDICATOR APPROXIMATE
- DRAG DEPENDENT UPON WIND RESISTANCE
ELECTRICAL GOVERNOR
1. +/- POSSIBLY COUPLED WITH RECHARGABLE BATTERY TO INDICATE CRANK
WIND
2. + ELECTRIC SPEED INDICATOR
3. + GOOD GOVERNOR SPEED CONTROL
4. - ADDITION OF MULTIPLE ELECTRICAL COMPONENTS
5. - COST OF GENERATOR & CIRCUIT BOARD
NO GOVERNOR – CENTRIFUGE ACTS AS FLYWHEEL
1.
2.
3.
+ ELIMINATES MECHANISN
- DIFFICULT TO BALANCE/CALIBRATE
- NO INDICATOR
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design
3 MINUTE ROTATION STOP
PUSH ROD TO RELEASE
SPRING LOADED
CATCH LEVER
GEAR REDUCTION STACK
INPUT SPROKET
Amir Torkaman • ENGR10 • Fa13
Applied Precision Design