ME 4182 Capstone Design Final Report Train Car Hopper Gate

Document Sample
ME 4182 Capstone Design Final Report Train Car Hopper Gate Powered By Docstoc
					       ME 4182: Capstone Design

              Final Report

Train Car Hopper Gate Automation Device




            Submitted by:
        Team “Flood the Gates”

            Amy Bolling
           Travis Palladino
           Michael Skrifvars
           Mike Silberstein
            Mehtab Wasi
ABSTRACT
       Rail transportation has been a key mode of transportation of goods since the 19th century
and it will continue to be integral in safely transporting bulk materials. In particular, trains are
commonly used to transport grain and phosphate via multiple cars with hopper gates on the
bottom of each car. Currently, in order to release these materials from the cars into storage is by
opening the gates by way of a large air gun forcing rack and pinion interaction. According to
CSX Transportation Company, this method has room for improvement, but new designs have not
yet been approached. After exploring multiple possibilities, Team “Flood the Gates” has chosen
this engineering task as the basis for ME 4182 Capstone Design. The goal of the project was to
solve the current design problems of inefficiency and excessive wear on the system. Conceptual
designs were deliberated over and placed into an evaluation matrix. After careful analysis of
design criteria, a final design was chosen involving linear actuation by means of a piston-
cylinder assembly.    Engineering calculations were then made to size the assembly for the
required forces involved. The design was then built and mounted on the hopper gate assembly.
After several trials, Team “Flood the Gates” has deemed this design to successfully meet the
design criteria and be a viable option for real-world implementation. This final report includes
the major aspects of the design process and completion.




                                                 1
TABLE OF CONTENTS


PROBLEM STATEMENT ............................................................................................................... 3
DESIGN PARTITION ..................................................................................................................... 5
DESIGN CONCEPT EVOLUTION AND ANALYSIS ..................................................................... 5
ENGINEERING ANALYSIS (PRELIMINARY) ............................................................................... 9
FINAL DESIGN ............................................................................................................................ 11
ENGINEERING ANALYSIS .......................................................................................................... 13
PROTOTYPE ................................................................................................................................ 13
ECONOMIC CONSIDERATIONS................................................................................................ 14
CONCLUSION.............................................................................................................................. 14
APPENDIX A: PART DRAWINGS ............................................................................................... 15
APPENDIX B: ENGINEERING ANALYSIS ................................................................................. 21
APPENDIX C: FINITE ELEMENT ANALYSIS............................................................................ 23




                                                                     2
PROBLEM STATEMENT
       The current method of opening an outlet gate involves manually attaching a pneumatic
tool to the end of the hopper gate shaft. This method is limiting because the pneumatic cart needs
to be attached to each hopper gate by an employee, and it is also damaging to the locking
mechanism of the gate to apply an indiscriminate amount of force to pry open the gate. The
hopper door requires air pressure from an external tool separate from the train in order to release
the door. Our proposed design would include a device already attached to the freight car and
connected across all three hopper chutes. Operation would be simply applying an air source to
the device and pushing a button to open or close the door. A design that would allow the hopper
door to open from a remote location would reduce time and manpower and also increase safety
of operation. Figures 1 and 2 represent photographs of the gate assembly that is connected to the
bottom of the rail car in the correct orientation for use and in the flipped orientation for design
purposes, respectively.




                    Figure 1: Hopper Gate Assembly in Correct Orientation



                                                3
               Figure 2: Hopper Gate Assembly (Opened) in Flipped Orientation


       The team chose to design by working on the apparatus in the flipped position as shown in
Figure 2. The figure shows the shaft to which the air gun currently attaches and the rack of the
gate to which the pinion of the shaft is connected and moves with rotational motion.
       Design problems include determining the amount of force necessary to open the gate, the
sizing of the pneumatic cylinder, securing everything to the underside of the car, and connecting
the power source to the door-opening component. A motor or movement mechanism must
deliver enough pressure to open the hopper door, attaching the motor to the train car and the
source of energy for the motor must be determined. Purchasers of the product may also be able
to open all hopper doors simultaneously rather than opening one door at a time per worker. The
air pressure to open the hopper door is still unknown. A motor must be sized to deliver enough
pressure to the door to open it. The motor must be mounted to the train. The product shall be
evaluated on consistency of use, the cost of each unit, and the amount of maintenance required



                                                4
which keeps the motors operable. The targeted market for this device is car owners which
includes private car owners, industries, and railroads.



DESIGN PARTITION
       Before exploring possible conceptual designs, it is important to first gain an
understanding of the basic functions that the device will have to include. This is done by design
partitioning. The hopper gate opener consists of three major partitions.
       The first partition involves the power production of the system. The source of the power
was considered most likely be compressed air, which is readily available on rail yards. This
compressed air can be supplied to a driving force such as a motor or pneumatic actuator.
       The second partition involves the challenge of structurally supporting the device.
Mounting the device correctly is essential to correct performance and long life of the entire
system. The gate assembly poses mounting problems as there are many angled and curved
surfaces. The building of a significant mounting assembly can also be considered.
       The third partition involves the coupling of the device to the actual gate that must be
opened. There are a few viable options for connection and different benefits and drawbacks to
each one. This is the area that requires the most innovation because this determination can
significantly reduce the total energy that needs to be produced by the opening system.



DESIGN CONCEPT EVOLUTION AND ANALYSIS
       Once the objectives for design became clear, the team was able to offer conceptual
designs for opening the hopper gate. Six designs were considered. The first five involved using
rotational motion via the rack and pinion method to open the gate and the sixth involves a direct
linear actuator connection.
       The first concept was called the Tachometer Control design. This design involved a
motor and PD control box that would react to increasing rotational motor velocity in order to
dampen the system for smooth opening. This design would alleviate stress on the contact
between rack and pinion.




                                                 5
       The second concept was called the Linear Damping design. This design involved a
dampening system inside a gearbox connected to a motor. This system was intended to dampen
the contact between the tooth and the pinion at the gate connection.
       The third concept was called the Pneumatic Cable design. This design consisted of two
linear actuators with dampers connected to the rotating shaft by way of cables. One actuator was
designed to open the gate and the other to close it.
       The fourth concept, the Spring-Damper design, also focused on a cable connection to the
shaft but in this case springs were attached to open the gate. Three springs were designed with a
clutch system that was intended to fire different springs in the process of opening the gate in
order to decrease the speed once the gate began to open.
       The fifth concept was called the Gear Reduction design. This design involved a motor
connected to a set of spur gears design to reduce the rotational speed by a large factor for smooth
opening while creating a large amount of torque. The gears can then connect directly to one of
the pinions on the shaft.
       The sixth concept was called the Pneumatic Actuator design which involved a large
cylinder designed to attach to the gate in such a way that it may provide the correct amount of
travel. The piston-cylinder would be actuated by compressed air.
       Once conceptualization was completed, it became necessary to explore what other
inventors had already patented to perform similar functions. Each team member searched online
for patents followed by group collaboration. Two of the patents found were for mechanisms that
included a special hopper gate for a railcar. One of which was similar to the current design with
a rack and pinion fitting for an air gun. Other designs showed methods for transferring energy
from a motor or actuators to a system of gears. Discussion about these patents affirmed the
general belief that the team’s design should involve either a pneumatic motor with a gear system
or the use of pneumatic actuators.
       After comparing the conceptual designs with patents, the designs were placed into an
evaluation matrix that would analyze the designs based on weighted criteria. The criteria, in
order of importance, included robustness, force produced, reliability, operating simplicity, cost,
building simplicity, safety, speed, and size. Table 1 displays the evaluation matrix.




                                                 6
                      Table 1: Evaluation Matrix for Conceptual Analysis
                                                   simple          easy to
                    robust   force   reliability            cost             safety   speed   size
                                                    oper.           build

   Weight Factor:     5      4.5         4           4       3      2.5        2       2       1     Score

    Tachometer
                      2       2          3           3       3       2         3       2       2     66.5
      Control


  Linear Damping      2       2          1           2       2       1         3       2       2     49.5


    Pneumatic
                      1       2          1           3       2       2         2       3       2      50
      Cable


  Spring-Damper
                      2       3          1           2       2       1         2       3       2     53.5
      System



  Gear Reduction      3       3          3           4       1       2         4       3       3      78



    Pneumatic
                      4       3          3           3       2       3         2       4       2     81.5
     Actuator



       As shown in the table, each criterion was given a weight factor of importance. These
factors were based on a scale of 1-5, where a weight of 5 was the most important and a weight of
1 was the least important. The design scores were based on a scale of 1-4, where a 4 was the
best score that could be achieved and a 1 was the worst score. The final weighted scores for each
concept are shown in the far right column. The Pneumatic actuator design scored the highest
with 81.5 points and the Gear Reduction design was close behind with 78 points. The other
conceptual designs had significantly lower scores.
       Through this part of the analysis, the team decided to further explore both the Gear
Reduction and the Piston-Cylinder designs to come to a final decision. After researching motors
and gears for the Gear Reduction design, it became evident that complications would occur in
reducing the gears to providing the correct torque and speed from the motor. Also, using one
motor and gearbox with a high ratio could only produce a torque of 200 ft-lbs which was half the
torque required for worst-case loading. This brought up the issue of possibly designing for two



                                                    7
motors, which would be very costly. On the other hand, the piston-cylinder concept seemed
more feasible after preliminary calculations were performed for sizing the cylinder. It also
seemed to be the most robust of all the designs. Hence, the team decided to pursue the Piston-
Cylinder concept as the basis for design, shown in Figure 3.




                          Figure 3: Piston-Cylinder Conceptual Design


       As shown in the figure, a pneumatic piston-cylinder assembly would be mounted in some
way to the frame. The piston would then attach to the gate slider for opening. However, this
design brought forth some questions. Can the cylinder be built for sufficient travel to fully open
the gate? How can the piston be connected to the gate to handle a large force? Will there be
enough room for mounting as the cylinder must have a large diameter? After considering these
questions and using preliminary engineering knowledge, the design was then further
conceptualized and is displayed in Figure 4.




                                                8
                            Figure 4. Modified Piston-Cylinder Design


       In this basic design, the cylinder is connected to the flange of the gate with a connector
angle. Two cantilever angles, a crossover angle, and a central door-piston connector would
provide the basic frame for connecting the force provided by the piston to the slider door. The
piston would be attached with a mounting bracket and connector angle.



ENGINEERING ANALYSIS (PRELIMINARY)
       With this system on hand, the next task that was approached was an engineering analysis.
The first part that needed to be considered was the piston-cylinder assembly. From an inquiry to
CSX Transportation, the maximum required torque to open the gate at worst-case loading
conditions was said to be 400 ft-lbs, applying to the end of the shaft at which the air gun
currently connects. This is also equal to the torque at the locations on the shaft directly above
the racks of the slider door. Using a simple moment equation, it was found that the torque
translated to a linear force of 1,920 lbs on the gate for opening at maximum load conditions. So,
from this force, it was determined that a cylinder of 7” would be an appropriate selection,



                                                 9
producing a force of 1,924 lbs. This size at first seemed excessively large, but when the team
looked further into mounting options, it was actually very feasible as the gate assembly is very
large in itself with robust connection points.
       The next part that needed to be approached was the travel of the piston which is equal to
the length of the assembly. This seemed to be a point of concern as to the increasing moment on
the system with increasing travel. After taking measurements on the slider door, it was decided
that this length would need to be 30”. The moment produced by this assembly will be further
discussed.
       The basic framing connections of the design were then approached. A detail of the pin
connection is shown in Figure 5.




                                     Figure 5. Pin Connection Detail


       The connection at the slider door and door-piston connection was first approached. This
is a pin connection that would involve bearing and shear stresses. Using the force that the
piston-cylinder would produce, the factors of safety for the bearing and shear stresses on the pin
were found to be 8.8 and 13.8, respectively with a material of ASTM A-36 steel (used for all
parts calculations). Further using simple moment equations, the factor of safety for the
cantilever angles was calculated to be 5.64.


                                                 10
       These calculations allowed the group to discuss and further refine the system into the
final design described above.



FINAL DESIGN
       The solution to this problem statement is shown in the final design of Figures 6, 7, and 8.
The part drawings for the final design are shown in Appendix A.




                             Figure 6. Final Design Isometric View




                                               11
Figure 7. Side View of Final Design




Figure 8. Front View of Final Design




                12
ENGINEERING ANALYSIS
       The calculations performed for the engineering analysis of components can be seen in
Appendix B. The pertinent finite element analysis on parts can be seen in Appendix C.



PROTOTYPE
       While the final design formed the basis for actual implementation into the current
infrastructure, the prototype is the design that was actually built and tested by the team. The
essential function of the prototype is to prove the concept offered by the final design. A picture
of the final prototype can be seen in Figure 7. The main difference from the final design to this
prototype is the size of the cylinder. For the prototype, the team decided to install a 4” diameter
cylinder as opposed to the 7” diameter cylinder.       The 7” cylinder would lead to building
difficulties within the realm of the tools available by the team in that is would have a large
weight. Also, its higher cost was not very appealing to the project budget. A 4” cylinder was all
that was needed to perform the operation under zero loading conditions and prove the basic
concept of the design. Furthermore, the travel of the piston was reduced to 30” instead of the
designed 32”. It was decided that the travel of the cylinder in the prototype would not disprove
the concept.
       The performance of the prototype was very successful. The team encountered a problem
of a leaking air valve sent from CSX, but still was able to get enough air to the cylinder for
opening and closing. The air for the prototype was supplied by an air compressor which
supplied the air through a smaller diameter hose than the hose connected to the valve. This
apparently caused fluctuations in the air supply that led to a “stop and go” functioning of the
cylinder during operation. Although, the prototype still performed its function of opening and
closing the gate relatively quickly.
       The final design and prototype described above were the culmination of the design
process over many weeks. Described below are the essential steps that were taken by the team to
form the successful design.




                                                13
ECONOMIC CONSIDERATIONS
        After completion of the final design, it became important to explore the feasibility of
actually implementing this system into an existing infrastructure. In particular, the team wanted
to see if this is something that a company such as CSX Transportation would seriously consider
putting in its rail cars. The two main aspects a company must consider for any new project is
cost and payback period. This type of analysis involves making base assumptions. For the
current hopper gate opening scenario, it was assumed that opening and closing the gates takes
about 4 hours for two workers. With labor at $20/hr for each worker and standard maintenance
on the equipment, the current system costs about $180 per full rail car operation. For the gate
opener system designed by Team Flood the Gates, the installation cost for all gates on a 100-car
train was estimated to be $23,000. However, with the newly established ease of opening in
closing, the time to perform the operation will likely reduce to 1 hour for just one person, or $25
for labor and maintenance. This leads to a payback period calculation of 148 operations for the
Pneumatic Actuator system. These types of rail cars are typically unloaded once or twice a
week, so this corresponds to a payback period of approximately 2 years. This payback time is
relatively short for rail cars that are in use for well beyond that time.



CONCLUSION
        This Capstone Design project has encompassed many aspects of engineering that have
been previously studied in the mechanical engineering curriculum. The project has allowed the
members of the team to apply engineering knowledge and the design process to a real-world
design scenario. Perhaps the most valuable thing that the team learned was that the design
process is never perfect in reality. In regard to the final design, it is the accumulation of several
compounded modifications and improvements. Each part of the system affects all of the others,
and simple changes may result in needed complex changes elsewhere. It was satisfying to see
the final result in action and look back on the entire design process. Beyond the realm of the
class, the team will follow up with CSX Transportation and discuss future implementation of the
final design and any recommended changes.




                                                  14
APPENDIX A: PART DRAWINGS




                            15
16
17
18
19
20
APPENDIX B: ENGINEERING ANALYSIS

AMY BOLLING
    6/25/2008

CALCULATIONS FOR ENGINEERING ANALYSIS


Part:          CROSSOVER ANGLE
Material Spec: A-36
Dimensions:               1.5 in X              1.5 in X                      0.25 in
      Length = 2 ' 8 11/16" = 32.6875 in                        I=           0.135 in^4           C=         0.46 in


Loading:        Simple supports - center load
                         F=         200 lb                                                Result of Calculation:
                                                                                          1.5 x 1.5 x 0.25" Angle produces FOS of 6.5
                              Fx Fl
                   M MAX =      =         Mmax =        1634.375 in-lb
                              2   4                                                       Properties:
                                                                                             weight per foot, w =      2.34 lb/ft
                            M MAX * C
                  σ MAX =             sigMAX=           5568.981 lb/in^2                              Area, A =        0.69 in^2
                                I

                  Factor of Safety, X =    6.464378
                *Assumes A-36 steel




Part:          CANTILEVER ANGLE
Material Spec: A-36
Dimensions:               2 in X                     2 in X                  0.375 in
                  Length =       37.5 in                        I=           0.479 in^4           C=        0.636

Loading:        Cantilever - end load
                         F=           100 lb                                              Result of Calculations:
                                                                                          2 x 2 x 3/8" angle produces FOS of 7.2
                 M MAX = F * L             Mmax =             3750 in-lb

                                          sigMAX =      4979.123 lb/in^2
                           M MAX * C
                 σ MAX =
                               I

                  Factor of Safety, X =    7.230189




Part:          ANGLE CONNECTING MOVING END OF ROD TO DOOR CONNECTION PIECE
Material Spec: A-36
Dimensions:                in X          in X            in
                  Length =       in            I=        in^4           C=

Loading:
                         F=               lb                                              Result of Calculations:

                 M MAX = F * L             Mmax =                    in-lb

                                          sigMAX =                   lb/in^2
                           M MAX * C
                 σ MAX =
                               I

                  Factor of Safety, X =    #DIV/0!




                                                                             21
Part:          ANGLE CONNECTING FIXED END OF CYLINDER TO GATE FRAME
Material Spec: A-36
Dimensions:                in X           in X             in
                  Length =       in             I=         in^4                           C=

Loading:
                         F=                lb                                     Result of Calculations:

                M MAX = F * L                Mmax =                in-lb

                                           sigMAX =                lb/in^2
                           M MAX * C
               σ MAX =
                               I

                 Factor of Safety, X =       #DIV/0!




Part:          DOOR-TO-CONNECTION PIN
Material Spec: A-36       Material Strength =              36000 psi
Dimensions:         Dia =     1.48 in                   Length =             in

Loading:      Pin with bearing and shear forces from pulling sheet
                                                                                  Result of Calculations:
                             d 2π
                A piston =               Cylinder D =          7 in
                               4           Apiston =    38.48451 in^2             Existing diameter in slider door of 1.48 in is
                                                                                  acceptable with A-36 steel. Resulting safety factors
                F = 50 psi * A piston             F=    1924.226 lb                of 8.6 in bearing and 13.5 in shear.

                            Gate thickness, t =             0.31 in
              Bearing Forces:          Pin D =              1.48 in

                Abearing = D * t          Abearing =      0.4588 in^2
                                          Pbearing =     4194.04 psi
                                F
                Pbearing =
                              Abearing          FOS =   8.583609

              Shear Forces:
                           πDt              Ashear =    0.720681 in^2
                Ashear =
                           2                Pshear =    2670.009 psi
                           F
               Pshear   =                       FOS =    13.4831
                          Ashear




                                                                       22
APPENDIX C: FINITE ELEMENT ANALYSIS




Figure C-1. Loading Conditions on Support Structure




                                  ME 4182: Capstone Design   9


Figure C-2. Max Stresses in Support Structure
.




                                                23
Figure C-3. Displacement in Support Structure




Figure C-4. Loading Conditions and Stresses in Lug Connector Placed in Tension




                                                24
Figure C-5. Loading Conditions and Stresses in Lug Connector Placed in Compression




   Figure C-6. Loading Conditions and Stresses in Existing Gate Frame in Tension




                                        25
Figure C-7. Loading Conditions and Stresses in Existing Gate Frame in Compression




Figure C-8. Stresses in Door and Pulling Channel Connection.




                                             26

				
DOCUMENT INFO