UPDATEDMid Semester Presentation.pptx
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Transcript of UPDATEDMid Semester Presentation.pptx
Semi-automated Thermoforming
SystemBrendan CrosbyLeon Hill
Rene Vallesteros
Jesus ToledanoSponsored by:
CalSci Inc.
Problem Statement
Build a semi automated thermoforming vacuum system for 1/16” -1/8" thick ABS and Acrylic measuring 24in. x 24in.
Requiring a uniform temperature exceeding 350℉ to be autonomously moved to a mold and pull minimum vacuum pressure of 10 psia.
Form 0.1-0.125in. thick Acrylic, and ABS plastic sheets.
Sheet dimensions: 24inx24in.Cannot heat plastic too quickly or too slowlyForming temperature: T≥ 350℉Pull vacuum pressure large enough to form plasticDepth of draw may not exceed 1/3 of smallest part width approximately 8 inches.Plastic must be formed before dropping below forming temp
Function
ConstraintsVacuum Thermoformer
● Plastic placed in machine● Heats plastic to forming
temperature● Plastic placed on mold● Vacuum pulls plastic
tightly around moldAutomated System
● Loads plastic into machine● Controls heat rate● Maintains constant
vacuum● Releases part from
machine
Systems
1
34
1.Structural Frame2.Oven3.Plastic Holding
Frame4.Drive System5.Vacuum System
2
5
Fig 1. System Model
Figure 2 (a): System in up position Figure 2 (b): System in up position
Structural Frame
● Comprised of 2”x2”x1/8” aluminum angles and particle board and sheet steel
● Will have to support weight of the oven, drive system, and vacuum system.
● System weighs 58 lbs22 lbs oven21 lbs pump12 lbs frame & plastic
Figure 3(a):Premade materials
Figure 3(b):Assembly
Figure 3(c):Completed
OvenManufacturing
• The oven is comprised of an internal and external cover.
• Internal cover housed the heating elements.
• Fiberglass insulation is covered by an external cover.
Figure 4(b): Fiberglass insulation in between internal and external covers
Figure 4(c): Two 725 watt heating elements
Figure 4(d): Oven shield comprised of wooden board covered in aluminum foil to help reflect and store heatFigure 4(a): Sheet metal oven sidings
Oven Analysis
Figure 5(b): Oven Circuit
1st law of Heat Transfer
Oven Differential Equation Matrix
Steady State Convection and Radiation
Figure 5(a): Transient Oven Response
Oven Air Temperature
Testing Results
Will put excel plot here
Testing by using an analog air thermometer taking measurements at 2 minute intervals. Will do several runs and to create a general trend that will be compared to theoretical values
Figure(s) 6() will go here.
Plastic holding Frame
• Frame moves plastic up to be heated then down to vacuum platen for forming
• The frame wanted to tip and bind inside the structural frame
• Bearing sliders had to be redesigned to prevent tipping and binding
• Weighs roughly 12 lbs Figure 7(c): Plastic holding frame clamped to a piece of acrylic
Figure 7(a): Visiting Japanese ME student Kyosuke Kurokawa assembling plastic holding frame
Figure 7(b): Bearing sliders
Plastic Analysis
Figure 8(b) Testing results plot
Figure 8(a) Transient Plastic Heating
1D Conductive Heat Transfer
Nodal Numerical Analysis
Resulting Plot
Plastic Results
Drive System
● Comprised of laser cut ABS, ½” aluminum driveshaft, DC motor, and coil springs
● Coil springs offset the weight of plastic frame reducing motor size
● Arms are glued together and interference fit onto drive shaft
Figure 9(a) Drive shaft and controls table
Figure 9(b) Laser cut ABS for drive arms
Drive System Analysis
● F is weight of frame, F=12lbf● T = F*L*cos(Ө)
Where L = 9” ; Ө = Ang Position● Worst case Ө = 23°● T = 99.4 in-lbf● This model assumes frictionless
bearings
Results● Measured with torque wrench on the
end of drive shaft
Tactual = 110 in-lbf
Figure 10 GIF of torque wrench testing drive system
Vacuum System
● Vacuum below part allows pressure of atmosphere to form heated material onto mold
● Plastic must seal to vacuum platen
● With 1mm plastic 3.5 inHg vacuum will form part
● High CFM pulls heated plastic over platen more efficentily than low CFM with high vacuum pressure.
Figure 11(a): Part to be formed laying on vacuum platen
Figure 11(b): Part formed over using 1mm ABS sheet
Overall System
Comment: GIF of system -->
Figure 12 complete system in operation (GIF)
Special Thanks to:
• Sponsor:Mark Lawrence|CalSci Inc. • Professor: Dr. Vogt• Assistant professor:
Efrain Garcia• Professor: Dr. Zhou• James Mullinix (SDSU)
Questions?
ReferencesRosato, Donald, Ph.D, Marlene Rosato, PE, and Nich
Schott, Ph.D. "3G Thermoforming." Plastics Institute of America: Plastics Engineering, Manufacturing & Data Handbook. By Dominick Rosato. Vol. 1. Boston: Kluwer, 2002. 886-977. Print.
Ogorkiewcz, R. M., ed. Engineering Properties of Thermoplastics. Bristol: Wiley-Interscience, 1970. Print.
Mizra, Sohail. "Overview of Industrial Motor Control Systems." Design Support. Maxim Integrated, May 2010. Web. 15 Feb. 2016.
“Vacuum Forming Tutorial.” Massachusetts Institute of Technology, Web. 15 Feb. 2016.
Taylor, C. A., Delorenzi, H. G. and Kazmer, D. O. (1992), “Experimental and numerical investigations of the vacuum-forming process”. Polym Eng Sci, 32: 1163–1173. doi: 10.1002/pen.760321613