Final Design Review Report Design of a Particulate Material Compression Feed Screw for Research and Data Collection Submitted to: Dr. Marcial Gonzalez Dr. Carl Wassgren Dr. Charles Jensen Abhishek Paul Submitted by: The Feed Screw Speed Crew: Marcus Gunyon Mohammed Matar Josh Meiners Evan Selking Yun-Jui Jeremy Tu Rachel Wasem 8/4/2020
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Final Design Review Report - Purdue University...2020/08/04 · cause 50 psi, 30 psi, and 15 psi of pressure on the fed material. A closer view of the pressure plate apparatus can
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Final Design Review Report
Design of a Particulate Material
Compression Feed Screw for Research and
Data Collection
Submitted to:
Dr. Marcial Gonzalez
Dr. Carl Wassgren
Dr. Charles Jensen
Abhishek Paul
Submitted by:
The Feed Screw Speed Crew:
Marcus Gunyon
Mohammed Matar
Josh Meiners
Evan Selking
Yun-Jui Jeremy Tu
Rachel Wasem
8/4/2020
Page 2 of 115
Executive Summary:
Our mission was to produce a cost-effective, modular tabletop design of a compression
feed screw for formulation and validation of predictive models of torque, angular speed, and
mass flow. Currently, the project is prepared for fabrication, as all manufacturing and systems
design is complete. The team members’ leads, charter, and schedule can be found in Appendix
A, B and D. The focus of this phase has been finalization of the prototype and validation of met
engineering requirements, summarized in Table 1 below and detailed in Appendix Q:
Table 1: Customer Requirements and Validation of Parameters
Close attention to mitigation of risk (Appendix E) and adherence to the project budget
(Appendix C) resulted in a safe and readily accessible means of data model validation costing
tens of dollars instead of thousands per test. Providing a personal feed screw also allows for
more thorough improvement in the researcher’s models, leading to exponentially larger
improvements and smaller costs of feeding issues in multi-million dollar biorefineries, saving
them up to $1,000,000 per year. The final prototype, as pictured in Figure 1 below, was
mechanically and electronically designed to provide repeatable feeding experiments while
producing useful data for model validation.
Page 3 of 115
Figure 1: Photo-Realistic Render of Fully Assembled Device
The mechanical model was dimensioned as a scale model (Length: 53 in. Width: 9.5 in.
Height: 10.5 in., Weight: 103 lbs) of a provided basic feed screw. The team innovated this design
to include clamshelled casing, flexible chain coupling, a motor and modular supporting stand,
and a simulating, spring loaded back-pressure plate to resist flow of biomass. The basic model
alone was previously unable to collect or electronically record any operational data, lacked
flange connections, and only included 4 total parts. Perhaps the largest innovation made was the
creation of the pressure plate, made up of a 45 degree cone extruding to block the end of the
plug, forced against fed particulate material by 4 15 lbs/in springs. The springs are pushed by a
1/16 in. A36 Steel plate that butts up against a load cell, which is attached to a supported 9.5 in.
square plate. The 9.5 in. plate’s supports are then screwed into one of 5 potential steel insert
locations. These locations were chosen specifically to provide spring displacements that will
cause 50 psi, 30 psi, and 15 psi of pressure on the fed material. A closer view of the pressure
plate apparatus can be seen below in Figure 2. Appendix G illustrates all the innovations made to
the physical design, while Appendix H validates operability. Products of the design process,
including benchmarks and sketches exist in Appendices N and F respectively.
Page 4 of 115
Figure 2: Photo-Realistic Render of Pressure Plate Apparatus
The device allows for user control of motor speed, controlled by a potentiometer. Once
running, an Arduino collects readings of shaft speed, motor power, pressure load, torque, and
strain on 12 different bolt connections and records them each second. This data is placed into
visual time graphs, highlighting maximum and minimum values and when variations may occur.
The mass flow is also measured using a simple scale underneath the exit of the feed screw, from
which average mass flow is calculated by dividing mass collected by time of operation. A wiring
diagram, displaying the Arduino based circuit is seen below in Figure 3, while Figure 4 shows
the data table and example graph that the operator would see automatically updating while
running the device. Appendices I, J, and K contain further details, as well as the electronic
schematic, Arduino code, and a flow chart.
Page 5 of 115
Figure 3: Full Wiring Diagram
Page 6 of 115
Figure 4: Automatically Updating Example Graph and Data Collection Table
The parts as seen in Figure 1 will be manufactured 1 of 3 ways: Xometry custom
manufacturing, personal manufacturing at Bechtel Innovation Design Center, or pre-
manufactured part orders. Manufacturing drawings for parts produced in BIDC or Xometry can
be found in Appendix L, and links for any needed purchases are found in Appendix R. Further,
Appendices M, O and P outline what was learned from each of the three prototypes produced
during the project, the basic physics model of the device, and a list of standards referenced.
Appendix U was used to confirm the necessary tolerances of these manufactured parts.
Given all this information, the team requests that the researchers fabricate and assemble
the design using steps listed in Appendix S, the manufacturing plan laid out in Appendix T, and
apply all physical validations stated in Appendix Q before operating.
Page 7 of 115
Contents
Appendix 8
A: Team Members and Organization Structure 8
B: Charter 9
C: Business Case and Project Budget 10
D: Work Breakdown Structure and Project Schedule 13
E: Risk Mitigation 15
F: Sketches 17
G: Mechanical CAD 30
H: Mechanical CAE 36
J: Arduino Code 54
K: Flow Chart of Control/Operation 63
L: Manufacturing Drawings 67
M: What was Learned from the Low, Mid, and High-Fidelity Prototypes 86
N: Benchmark research 88
O: Basic Physics Model (Free Body Diagram) 91
P: Standards Referenced/Used/Applied 96
Q: Testing and Validation 98
R: Links to Purchased Components and Display Videos 100
S: Assembly Instructions 104
T: Manufacturing Plan 112
U: Table of Fits and Tolerances 115
NOTE:
For the Final Design Review (FDR), each Appendix was finalized. The updated
appendices from the Critical Design Review (PDR) exist in appendices A through P. While they
were created for the PDR, they reflect progress made in preparation for the CDR and FDR.
Significant changes from CDR to FDR can be found in Appendices F, G, H, J, L, M, P, Q, R, S
and T. All new appendices created specifically for the CDR exist after Appendix P.
Page 8 of 115
Appendix
A: Team Members and Organization Structure
The roles and coverage of the six members of the Feed Screw Speed Crew has not
6. Purchased and Modified Parts ……………………………………….………….85
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7.11
R1.73
.50
6.61
.10
4.07
.25 x4
3.31
3.56 .25
.50
1.00
1.50
1.25 Dimensions symmetric across centerline
A A
B B
4
4
3
3
2
2
1
1
6061-T6 ALUMINUM
FEED SCREW SPEED CREW
1DO NOT SCALE DRAWING
Motor Back Frame
SHEET 1 OF 1
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UNLESS OTHERWISE SPECIFIED:
Scale: 2:3 WEIGHT:
REVDWG. NO.
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TITLE:
NAME DATE
COMMENTS:
CHECKED
DRAWN
125 µin FINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX±0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
THE FEED SCREW SPEED CREW. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
THE FEED SCREW SPEED CREW IS
PROHIBITED.
Page 71 of 115
7.110
R1.575
0.500 6.610
0.131
4.073
3.500
4.000
0.250
0.500
3.305
3.555
0.250 x4
Dimensions symmetric across centerline
A A
B B
4
4
3
3
2
2
1
1
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1DO NOT SCALE DRAWING
Mid Motor Frame
SHEET 1 OF 1
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DRAWN
125 µinFINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX±0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
THE FEED SCREW SPEED CREW. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
THE FEED SCREW SPEED CREW IS
PROHIBITED.
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R1.000 R1.500
0.615
6.495
7.110
2.055
2.555
4.555
5.055
4.100
0.100
5.100
0.250 x2
3.247
3.555
0.250
0.500
0.750
Dimensions symmetric across centerline
A A
B B
4
4
3
3
2
2
1
1
6061-T6 ALUMINUM
FEED SCREW SPEED CREW
1DO NOT SCALE DRAWING
Hopper Frame Back
SHEET 1 OF 1
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SCALE: 2:3 WEIGHT:
REVDWG. NO.
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TITLE:
NAME DATE
COMMENTS:
CHECKED
DRAWN
125 µinFINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX±0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
THE FEED SCREW SPEED CREW. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
THE FEED SCREW SPEED CREW IS
PROHIBITED.
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.62
6.49
7.11
.250 x2
R1.50
3.35
.10
4.10
R1.78
0°
45° 135°
3.25
3.56
.250 x2
.25 .50
A A
B B
4
4
3
3
2
2
1
1
6061-T6 ALUMINUM
FEED SCREW SPEED CREW
1DO NOT SCALE DRAWING
Hopper FrameSHEET 1 OF 1
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SCALE: 1:1 WEIGHT:
REVDWG. NO.
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DRAWN
125 µinFINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX±0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
THE FEED SCREW SPEED CREW. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
THE FEED SCREW SPEED CREW IS
PROHIBITED.
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.62
6.49
7.11
R1.50
.25 x2
.10
3.35
.75
0°
45° 135°
R1.76
3.56
.25
3.25
.25 x2
.50 View is symmetrical about centerline
A A
B B
4
4
3
3
2
2
1
1
6061-T6 ALUMINUM
FEED SCREW SPEED CREW
1DO NOT SCALE DRAWING
Big Plug Frame
SHEET 1 OF 1
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DRAWN
125 µinFINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX±0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
THE FEED SCREW SPEED CREW. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
THE FEED SCREW SPEED CREW IS
PROHIBITED.
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7.11
.62 6.49
R.13 x2
R1.00
3.22
4.10
.10
3.25
3.56
.50 .25
.25 x2
.88
3.25
Dimensions are symmetric across centerline
A A
B B
4
4
3
3
2
2
1
1
6061-T6 ALUMINUM
FEED SCREW SPEED CREW
1DO NOT SCALE DRAWING
Small Plug FrameSHEET 1 OF 1
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SCALE: 1:1 WEIGHT:
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TITLE:
NAME DATE
COMMENTS:
CHECKED
DRAWN
125 µinFINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX±0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
THE FEED SCREW SPEED CREW. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
THE FEED SCREW SPEED CREW IS
PROHIBITED.
jensen23
Sticky Note
you do not have a 2 place tolerance only a 3 place tolerance.
Page 76 of 115
.50
2.00
2.00
1.79
2.22
.50
.50
.50
.13
.19
.44
.87
.86
6.29
9.79
1.79
2.22
.24 x30
16.31 11.61 1.25 12.87 9.41
1.06 5.30 .70 4.31 .70 3.40 1.06 3.50 5.25 1.01
52.01
3.28
3.31
3.30 3.25
3.31
4.75 3.56
2.70
.25 x20
1. Unless otherwise specified, dimensions are symmetric across the centerlines in both views
NOTES:
2. Every grouping of five holes in the enlarged view maintains the same relative location to each other. The leftmost and bottommost holes have been located in each group to apply the relative locations. This view is an enlarged section (1:1 scale) of the top view
A A
B B
C C
D D
8
8
7
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FINISH
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DIMENSIONS ARE IN INCHES
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PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
<INSERT COMPANY NAME HERE>. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
<INSERT COMPANY NAME HERE> IS
PROHIBITED.
RW
08-03-2020
6061-T6 ALUMINUM
125 µin
Page 77 of 115
4.00
.30 1.00
3.15
6.85
3.68
5.00
.33 1.95
2.50
3.16
.50 x2
.72
A A
B B
C C
D D
8
8
7
7
6
6
5
5
4
4
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2
2
1
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FEED SCREWSPEED CREW
1DO NOT SCALE DRAWING
Base Top View
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DRAWN
FINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX ± 0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
<INSERT COMPANY NAME HERE>. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
<INSERT COMPANY NAME HERE> IS
PROHIBITED.
RW
08-03-2020
6061-T6 ALUMINUM
125 µin
Page 78 of 115
.74
A A
B B
C C
D D
8
8
7
7
6
6
5
5
4
4
3
3
2
2
1
1
FEED SCREWSPEED CREW
1DO NOT SCALE DRAWING
Base Right View
SHEET 3 OF 3
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FINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX ± 0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
<INSERT COMPANY NAME HERE>. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
<INSERT COMPANY NAME HERE> IS
PROHIBITED.
RW
08-03-2020
6061-T6 ALUMINUM
125 µin
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4.00
2.50
1.00
.25 x4
0°
45° 135°
225° 315°
1.25
.25
2.75
3.00
3.90
4.00
1.50
1.25
2.00
2.50
3.00
Dimensions symmetric across centerline
A A
B B
4
4
3
3
2
2
1
1
6061-T6 ALUMINUM
FEED SCREW SPEED CREW
1DO NOT SCALE DRAWING
Hopper
SHEET 1 OF 1
RW 08-03-2020
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UNLESS OTHERWISE SPECIFIED:
SCALE: 2:3 WEIGHT:
REVDWG. NO.
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TITLE:
NAME DATE
COMMENTS:
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DRAWN
125 µinFINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX±0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
THE FEED SCREW SPEED CREW. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
THE FEED SCREW SPEED CREW IS
PROHIBITED.
Page 80 of 115
R.750
R.988
R1.263
R2.000
.250 x2
0°
45° 135°
R1.735
4.760
2.853°
47.853°
.250
3.910
.550
1.992
1.989
.986
.986
.250 x4
2.000
2.000
2.489
.100
1.000
4.010
4.910
5.010
R1.500
Dimensions are symmetrical across centerline
A A
B B
4
4
3
3
2
2
1
1
6061-T6 ALUMINUM
FEED SCREW SPEED CREW
1DO NOT SCALE DRAWING
ThroatSHEET 1 OF 1
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125 µinFINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX±0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
THE FEED SCREW SPEED CREW. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
THE FEED SCREW SPEED CREW IS
PROHIBITED.
Page 81 of 115
.250 x4
R2.000 R1.500
R.625
2.498
0°
45° 135°
R1.749 R1.249
.250 x4 45° .125
1.500
1.250
1.497
1.998
.100
1.000
5.000
5.900
6.000
.077
Dimensions are symmetric across centerline
A A
B B
4
4
3
3
2
2
1
1
6061-T6 ALUMINUM
FEED SCREW SPEED CREW
1DO NOT SCALE DRAWING
PlugSHEET 1 OF 1
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125 µinFINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX±0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
THE FEED SCREW SPEED CREW. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
THE FEED SCREW SPEED CREW IS
PROHIBITED.
Page 82 of 115
.999 .848
8.740
14.500
20.125
.75°
1.000 4° .633
.380
A A
B B
4
4
3
3
2
2
1
1
STEEL 4130
FEED SCREW SPEED CREW
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ScrewSHEET 1 OF 1
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125 µinFINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX±0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
THE FEED SCREW SPEED CREW. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
THE FEED SCREW SPEED CREW IS
PROHIBITED.
Page 83 of 115
3.00
3.00
.25 x4
1.50
1.50
2.50 0°
44.82° 134.82°
224.82° 314.82°
.50
60°
2.23
.50
.56
A A
B B
4
4
3
3
2
2
1
1
A36 STEEL
FEED SCREW SPEED CREW
1DO NOT SCALE DRAWING
Pressure PlateSHEET 1 OF 1
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125 µinFINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX±0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
THE FEED SCREW SPEED CREW. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
THE FEED SCREW SPEED CREW IS
PROHIBITED.
Page 84 of 115
.250 x4
9.500
9.500 .063
A A
B B
4
4
3
3
2
2
1
1
A36 Steel
FEED SCREW SPEED CREW
1DO NOT SCALE DRAWING
Back PlateSHEET 1 OF 1
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125 µinFINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX±0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
THE FEED SCREW SPEED CREW. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
THE FEED SCREW SPEED CREW IS
PROHIBITED.
Page 85 of 115
.079 .453
Note: Bolt purchased from McMaster Carr
A A
B B
4
4
3
3
2
2
1
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YELLOW CHROMATE-PLATED ZINC
FEED SCREW SPEED CREW
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125 µinFINISH
MATERIAL
DIMENSIONS ARE IN INCHES
TOLERANCES:
X.XXX±0.005
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
THE FEED SCREW SPEED CREW. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
THE FEED SCREW SPEED CREW IS
PROHIBITED.
Page 86 of 115
M: What was Learned from the Low, Mid, and High-Fidelity Prototypes
Appendix M includes the insights gained from the design process of each stage as labeled
below. Lessons learned from the CDR have been included towards the bottom of this section.
Low-Fidelity Prototype:
From the low fidelity prototype the team learned that it must ensure modularity of parts,
proper sensor placement, and simple supports. While designing the modularity of the barrel, the
team learned it had to either maintain a constant outside diameter across all modular parts or
ensure the base structure was able to adjust to components of varying diameters.
Further insights gathered from the low-fidelity prototype were possible locations for
sensor placement. This forced each section to be considered separately in the design process.
For example, the motor and its connection were isolated and determined to be the best fit for a
hall effect sensor that will track the rotation of the shaft. Flanges were added to allow the barrel
to open and to provide locations for strain gauges to measure the stresses of the structure. A scale
was added to capture fed material to determine mass flow rate out, and the back pressure plate
was designed to incorporate a pressure sensor to allow the simulated pressure to be measured and
adjusted.
The final insights were in relation to the support structure. There were several designs
considered, but ultimately, the team learned it was simplest from a manufacturing and design
perspective to create a set of simple supports to elevate the screw system and connect it to the
baseplate.
Mid-fidelity Prototype:
The mid-fidelity prototype allowed the thicknesses of parts and tolerances in connection
areas to be validated. For example, the shaft was determined to be an R4 fit due to the pressures
experienced by that section of the shaft. For the bolts, an LC3 fit was determined to be proper
due to the tighter tolerances. This will prevent the internal casing from shifting and interfering
with the screw. The mid-fidelity prototype also required a deeper analysis of sensor locations.
The E-stop was placed on a panel for easy reach. The force plate and scale had to be designed to
not interfere with each other as they occupy a similar space. The force plate required a thicker,
reinforced section of the stand in order to provide support for the desired pressures.
FEA analysis was performed on the inside of the casing and was able to verify the
thickness was correct. The shaft was analyzed using a simple mathematical model and the
material properties and factors of safety were found to be much higher than desired. This allowed
a smaller design to be considered, however the current system was still viable within the
specified design parameters, so the design was not changed.
High-Fidelity Prototype:
When completing the high-fidelity prototype, the team updated and improved the back
pressure plate. A concern was raised about the springs being compressed by the material exiting
the plug and not falling into the collection bin. To combat this, the back pressure plate was
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changed to a conical shape without the tip. The center of the plate would be a flat circle the same
size as the screw. The angled sides interacting with the material will push the material radially
outwards, forcing it to fall into the bin. This will decrease the fluctuation of back pressure by
reducing the length fluctuation of the spring.
Another lesson learned regarding the back pressure plate was the need for additional
support to the wall supporting the springs (pushing the plate into the plug of the screw). To
overcome this, 2 L-brackets were added to the back of the plate. These L-brackets also make it
easier to move the support plate forward and backward to adjust the back pressure.
To create a prototype that is easier to work with, the inner diameter was scaled down
from 2” to 1.5” and 1.25” (2 test cases). This will allow testing to be done on a table top and
keep the device from getting too heavy. It will also cut costs. Since this device will only be used
for testing purposes, rather than full-scale production, a size-reduction made sense in every
aspect.
After discussing pros and cons of balancing rpm and torque in a motor, the team decided
it was best to sacrifice some speed for extra torque. This is because when testing, it will be more
important that the motor is able to push the material out when up against the back pressure, than
how fast the motor is able to turn. It was impossible to find a motor that fit the size requirement,
5+ rpm, and 500+ Nm torque. The team decided on a 24V DC Motor Low Rpm High Torque DC
Planetary Reduction Gear Motor that could spin at 4 rpm and had 543.4 Nm torque. This motor
has slightly under 5 rpm and is able to exceed the 500 Nm torque requirement. The team was
much more comfortable sacrificing speed for torque to reduce jamming of the material inside the
casing in a case where the motor would not be strong enough to push the material out, one of the
researchers’ main concerns.
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N: Benchmark research
Appendix N contains information relating to similar designs to the desired feed screw
that already exist. This includes multiple Figures that highlight different aspects of the
benchmarks.
The Screw and Barrel System by Dynisco
The price of this benchmark is not provided on their website. This design seems to
be very comprehensive and expensive, which goes against the requirement of keeping the
table-top feed screw inexpensive. Because our design only uses milled or pelleted biomass
into chemical reactor vessels, the feed screw can be simplified and focused to keep costs
low.
One of the existing benchmark solutions is The Screw and Barrel System by
Dynisco. Figure 58 shows the components of this screw and barrel system design. The
screw consists of three different sections: the feed zone, transition zone and metering zone.
The compression ratio, which is the ratio of the volume of the flight in the feed zone to the
volume of the flight in the metering zone, is 3:1 for their design. This design also provides
a variety of different screw types according to each material or process, such as the
extrusion screw shown in Figure 59. They also provide multiple methods to achieve screw
mixing in order to deliver the material at a constant and controllable rate. Figure 60 and
Figure 61 show the dispersive mixing and distributive mixing, respectively. The static
mixer in Figure 62 is the device to perform the mixing methods. The screen packs, with the
support of breaker plates, build up pressure in a machine to uniformly heat, melt, and mix
the material, as shown in Figure 63. Both AC and DC motors could be used in their design.
The price of this benchmark is not provided on their website. This design seems to
be very comprehensive and expensive, which goes against the requirement of keeping the
table-top feed screw inexpensive. Because our design only uses milled or pelleted biomass
into chemical reactor vessels, the feed screw can be simplified and focused to keep costs
low.
Figure 58: The Basic Extrusion Screw Design
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Figure 59: Elements of an Extrusion Screw
Figure 60: Dispersive Mixing
Figure 61: Distributive Mixing
Figure 62: Static Mixer
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Figure 63: Breaker Plate and Screen Pack
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O: Basic Physics Model (Free Body Diagram)
Appendix O contains free body diagrams and force analysis of different aspects of the
screw. Additional analysis from the FDR has been appended to the end.
The main forces concerning this project will be torque applied by the motor, pressure
from the back-pressure plate, and normal force by the tapered walls. The torque can be
calculated, utilizing a volt sensor attached to the motor, and an RPM sensor we plan to have
attached to the driveshaft. The back-plate pressure will be measured utilizing the force sensing
plate itself. Finally, the normal force on the tapered walls can be found using strain gauges
attached to the flanges holding the tapered, clamshell section together. These forces are shown
below in Figure 64.
Figure 64: Force Identification upon Powdered Microcrystalline Cellulose
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In Figure 65, to estimate the bending moment, the end of the shaft connected to the motor
was simulated as being fixed to the wall, disallowing rotation. The weight of the shaft was
calculated using the density of Aluminum 6061 (2.7 g/cm^3) and the volume of the shaft. This
then showed the shear forces and bending moment the shaft would experience at any point in its
operation due to the force of gravity. This estimation was used in the subsequent calculations as
the bending moment experienced by the shaft.
Figure 65: Force diagram of shaft
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Figure 66 calculates the factor of safety of the shaft in operation. Using the maximum
specified torque and the bending moment found in Figure 65 above, the factor of safety was
found to be 9.14 for normal operation and 8.184 for the possibility of a static failure in the first
load. The first factor of safety was calculated using the Goodman criteria because it is an
extremely conservative estimate. This should ensure a safe design. Both factors of safety are well
above the minimum factor of safety of 2, indicating this is a good design that could theoretically
be adjusted to reduce the factor of safety, thereby reducing space and cost of the system.
Figure 66: Factor of safety during operation of shaft
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Figure 67 calculates the minimum possible diameter for the desired factor of safety of 2
for the operation of the shaft. It uses the Goodman criteria to remain consistent with other
calculations of the factor of safety. Using this, it was found that the minimum acceptable
diameter to retain a factor of safety of 2 was 1.537 inches.
Figure 67: Minimum possible diameter calculations
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Figure 68 estimates the factor of safety in an instance where the material flowing through
the feeder compacts and the motor stalls. In this event, the weight of the shaft is supported on
both ends by the compacted material and the motor, so it experiences pure torsion. It used the
factor of safety of yielding to check for yielding. The factor of safety was found to be 8.203,
comparable to the value found previously for shaft operation. The equation was then rearranged
to solve for the minimum diameter of the shaft, which was found to be 1.829 inches. This
confirms that the current shaft design is within the desired factors of safety and can withstand the
forces experienced when the material plugs the feeder.
Figure 68: Factor of safety and minimum acceptable diameter during stall
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P: Standards Referenced/Used/Applied
Appendix P has been included to show the standards identified and used in the design of
the screw and casing. They are used to determine the tolerances needed for each mating section
of the system shown in Appendix Q.
The first reference used below in Figure 69 is the American National Standard Running
and Sliding Fits ANSI B4.1-1967 (R2004). This table aided in the creation of the table of fits and
tolerances, seen in Appendix Q. The table was located at the following link:
http://www.zpag.net/Usinage/standard_ansiB4_1_1967.htm. This link also contained tables for
LC fittings which were utilized for analysis of bolt hole tolerances.
Figure 69: American National Standard Running and Sliding Fits ANSI B4.1-1967 (R2004)
The following drawing in Figure 70 is a reference provided in class by Dr. Jensen. This
example part drawing helped the team formulate part drawings in preparation for FDR.