MCHE 363 Final Design Report

Project: MCHE 363 DesignInstructor: Dr. Sally McInerny

Authors: Daniel Newman, Matt Gurnik,Derick Huval, Landon Latiolais, Gage Melancon

Date: December 10, 2014

MCHE 363 Final Design Report

TABLE OF CONTENTSPage

1.0 IDENTIFICATION OF NEED................................................................22.0 BACKGROUND RESEARCH.................................................................22.1 Scissor Lift 22.2 Threaded Rod Lift32.3 Tripod Pulley 33.0 DESIGN REQUIREMENTS...................................................................34.0 PROPOSED DESIGNS..........................................................................44.1 Design 1 – Scissor Lift 44.2 Design 2 – Helical Rod 44.3 Design 3 – Surgical Tubing 54.4 Design 4 – Inflatable Bellows 54.5 Design 5 – Tripod 65.0 DESIGN SELECTION...........................................................................66.0 PROTOTYPE CONSTRUCTION AND EVALUATION.............................77.0 APPENDIX - CALCULATIONS........................................................................9

LIST OF ILLUSTRATIONSPage

Figure 1 - Current Can Setup..........................................................................................2Figure 2 - Scissor Lift......................................................................................................2Figure 3 - Threaded Rod Lift............................................................................................3Figure 4 - Tripod Pulley...................................................................................................3Figure 5 - Scissor Lift: Minimum Extension Figure 6 - Scissor Lift: Maximum Extension

4Figure 7 - Helical Rod Lift...............................................................................................5Figure 8 - Inflatable Bellows............................................................................................6Figure 9 - Constructed Prototype....................................................................................8

LIST OF TABLESTable 1 - Design Selection Matrix....................................................................................7

1.0 IDENTIFICATION OF NEED A solution is required for a volunteer group which uses a 44 gallon trash can to

store cooked chicken halves for a fundraiser. The existing setup requires the volunteers to reach further into the can as the day progresses, causing unnecessary

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MCHE 363 Final Design Report

strain. A simple means of lifting the chicken halves as the can empties to minimize this strain is required.

2.0 BACKGROUND RESEARCH Research was conducted to evaluate existing design solutions for applications

similar to the scope of this design. A summary follows.

2.1 Scissor LiftThe scissor lift mechanism is widely used in many industries to safely elevate a

payload to a desired height.

Figure 2 - Scissor Lifti

2.2 Threaded Rod LiftThreaded rods are widely used as a means of controlling the location of a specified device and could be modified for this design application.

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Figure 1 - Current Can Setup

MCHE 363 Final Design Report

Figure 3 - Threaded Rod Liftii

2.3 Tripod PulleyThis mechanism is used in hunting applications and could fit the needs of this design with little modification.

Figure 4 - Tripod Pulleyiii

3.0 DESIGN REQUIREMENTS To meet the given need, the design solution must:

Be resilient to food residue and the cleaning products that the volunteer group use to clean the can after events.

Not significantly reduce the amount of chicken that can be stored in the can

Be able to hold approximately 225 pounds of chicken Comply with FDA guidelines Be as simple and cost effective as feasible. Be able to lift the chicken halves to a comfortable height from which they

can be removed from the can, whether continuously or incrementally.

4.0 PROPOSED DESIGNS The designs presented in this report are as follows:

1. Modified scissor lift2. Threaded rod 3. Elastic tubing lift4. Inflatable bellows5. Tripod crane

4.1 Design 1 – Scissor LiftThe ratio of maximum lift to minimum height for the scissor lift design is

extremely appealing. Additionally, the single point of actuation required by the scissor lift provides for several options regarding the application of force. Finally, proper design of this mechanism should minimize the footprint of it, possibly eliminating the need for an external force application.

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MCHE 363 Final Design Report

Manufacturing of this design will most likely prove to be quite complex and reliant on precise measurement. Additonally, this design has many moving parts contained within the can and would be exposed to food particles, making cleaning and maintenance a problem.

Figure 5 - Scissor Lift: Minimum Extension Figure 6 - Scissor Lift: Maximum Extension

4.2 Design 2 – Helical RodThis design is based on the threaded rod lift mechanism referenced in the

background research of this report. It has few moving components and therefore would be theoretically easy to manufacture.

Preliminary research into the cost of such a threaded rod indicates that this design would be relatively expensive. Additionally, the threads themselves present a food contamination hazard, as they need to be lubricated to function properly. The potential for bits of food to interfere with the function of the threads is another point of concern for this design. Furthermore, the proposed mechanism would significantly reduce the effective storage space of the can.

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MCHE 363 Final Design Report

Figure 7 - Helical Rod Lift

4.3 Design 3 – Surgical TubingThis design is based on the use of stored elastic energy of a material such as

surgical tubing to oppose the weight of the chicken in the can in a pulley application. In theory, platform in the can would slowly rise as chicken is removed from it without any external force application. This design is appealing due to its potential simplicity and ease of use.

The primary concern for this design is food safety and sanitation. Preliminary research has shown that the mechanics of this design are sound, but the materials from which surgical tubing is made are not FDA approved. Any assumed simplification in this design would be negated in an attempt to make it food safe and durable.

4.4 Design 4 – Inflatable BellowsThe premise of this proposed design is to incrementally inflate some sort of bag

to lift the chickens out of the can. The materials and manufacture would theoretically be expensive and the final product should be light and easy to transport.

Once again, food safety is a big concern with this design. The maintenance and cleaning of such a mechanism would likely be unmanageable. Additionally, this mechanism would be very fragile and catastrophically fail if anything goes wrong.

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MCHE 363 Final Design Report

Figure 8 - Inflatable Bellows

4.5 Design 5 – Tripod Based on the tripod pulley from the background research of this report, this

design has several advantages. First, it will be relatively lightweight and portable. Second, as the lifting mechanism will be external to the can, it will not reduce its effective capacity. Third, the materials will be relatively cheap as it is composed of aluminum and stainless steel hardware. Finally, there will be no issue with food safety as food grade aluminum and steel is readily available.

5.0 DESIGN SELECTION In order to properly weigh the proposed designs against one another, a design

selection matrix was created. As food safety is the only criterion by which a design can be eliminated, its weight is three times that of the other selection criteria.

 Selection Criterion Scissor Lift Screw Lift Inflatable

BagElastic Tubing Crane

Food Safety 3 1 2 1 3Simplicity of Construction 1 1 2 3 2Simplicity of Operation 3 2 1 3 3

Price 2 1 1 3 2Maintenance 2 1 2 2 3

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MCHE 363 Final Design Report

Alteration to can 2 2 3 2 3Score 13 8 11 14 16Weighted Average 2.4 1.3 1.9 2 2.8

Table 1 - Design Selection Matrix

Based on the selection criteria, the tripod crane design was chosen for construction.

6.0 PROTOTYPE CONSTRUCTION AND EVALUATION Preliminary calculations were performed to determine the size of aluminum pipe

for the legs of the crane (Appendix I). Based on these calculations, a prototype was built and tested. Though the design performed well in preliminary tests, the top plate to which the legs were welded failed in bending during final testing.

A few factors played into the failure of this prototype. First, the shop floor where the design failed was much smoother than the rough gravel where preliminary tests took place. As a result, there was no force stabilizing the feet of the tripod – a force which was present in preliminary testing. Second, it is likely that the anvil used in preliminary testing was only 150-200lbs in comparison to the approximately 225lbs under which the design failed.

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Figure 9 - Constructed PrototypeFigure 9 - Constructed Prototype

MCHE 363 Final Design Report

Realistically speaking, the prototype met all of the identified needs aside from the mechanical failure at 225lbs of weight in a worst case scenario loading. This issue can easily be fixed by adding additional thickness to the top plate. By welding a 0.5” plate on top of the existing prototype, a fully functional design solution to the identified need would be achieved.

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MCHE 363 Final Design Report

7.0 APPENDIX - CALCULATIONS

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MCHE 363 Final Design Report

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MCHE 363 Final Design Report

i Image taken from www.midlandpallettrucks.comii Image taken from www.ever-power.biziii Image taken from www.tradeindia.com

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