Design Project Introduction and General Instructions

Mech 323 ­ Winter 2005­6

One­Stage Reduction Gearbox for Conveyor­Belt

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Table of Contents 1 Introduction....................................................................................................................2 2 Application specifications..............................................................................................3

2.1 Belts.....................................................................................................................3 2.2 Gearbox design....................................................................................................4 2.3 Gear Attachment..................................................................................................4 2.4 Shaft Installation Considerations.........................................................................4

3 Format of project deliverables.......................................................................................5 3.1 Manual calculations............................................................................................5 3.2 Design drawings.................................................................................................5 3.3 Units of measure.................................................................................................6 3.4 Phase submission format....................................................................................6

4 Evaluation......................................................................................................................6 5 Teamwork......................................................................................................................6

5.1 Team formation...................................................................................................6 5.2 Teamwork TA.....................................................................................................7

6 Design assistance...........................................................................................................7 7 Summary descriptions of project phases .......................................................................7

Team formation ........................................................................................................7 7.1 Phase #1: Problem definition for Gearbox design..................….……..…..…...7 7.2 Phase #2: Spur gear train design ........................................................................8 7.3 Phase #3: Shaft design .......................................................................................8 7.4 Phase #4: Bearing/Seal Selection .......................................................................8

8 Appendix I: Sample Manual Calculation.......................................................................9

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1 Introduction

We are designing a one­stage gearbox for a conveyor belt on an automated tire manufacturing line. The conveyor belt is used to transport the tires, and is driven by an electric motor via the gearbox. The electric motor drives the input shaft of the gearbox through a flat belt over an input pulley. The output pulley is on the output shaft and is what the conveyor belt wraps over.

Figure 1 – Example of a conveyor Belt.

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2 Application Specifications

Output RPM from output shaft of the gearbox 40RPM with output power of 9 kW. Operation ­ 24hrs /day, 5days /week, 12 months/yr

2.1 Belts

Figure 2. Diagram of forces and torque on a Pulley

T is the torque, Nm; F1, F2 are the force acting on the pulleys through the belts, N; D is the diameter of the pulley, m; φ is the wrap angle of the belt, rad; Fi is the initial tension force applied to the belt, N; Fc is hoop tension due to centrifugal force, N; V is linear velocity of the belt, m/s.

­ Wrap angles φ are 210° for the pulley on the input shaft, and 180° for the pulley on the output shaft of the gearbox.

­ The coefficient of friction is 0.8 for both conveyor belt and input flat belt. ­ The linear velocity of the input flat belt is 4m/s. ­ Range for belt widths is 127 ­ 178 mm. ­ Choose a value for gear ratio from 4 to 5.

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2.2 Gearbox design

­ The gearbox is to have 1 stage reduction ­ The gearbox is to have an estimated lifetime of 10years ­ Gear material: AISI 4140 ­ Shaft material: AISI 4340

Fig.3 – Diagram for general layout of the gearbox

Fig. 3 shows a general arrangement. Note: input from motor and output to conveyor pulley are on different sides of the gearbox. Also note the direction of the flat belt and the conveyor belt, as this will become important when analyzing bending properties. The input and output shafts are the same elevation from the floor. The centerlines that bisect the wrap angles of each belt are horizontal. Thus the forces from the belts acting on the shafts are purely in the horizontal direction.

2.3 Gear Attachment

The pinion and gear will be fixed and located on the shafts by use of shoulders, spacers, keyways/keys, etc. You will need to decide how all these items are to be arranged on the shafts.

2.4 Shaft Installation Considerations

When deciding how to arrange the shaft assemblies, some things to consider with regard to how the assembly will be installed are:

­ Can each part of the assembly be placed on the shaft (i.e. no shoulders in the way)?

­ Are all parts ‘located’ on the shaft ­ Is there only one ‘locating’ bearing

Flat Belt

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3 Format of project deliverables

This design project is comprised of four phases. Each of the submissions that your Team will produce should be concise, well organized and easy to follow. Sections 3.1 to 3.4 describe, in general terms, the required format for the deliverables associated with each of these phases.

3.1 Manual calculations

Where you are requested to submit manual calculations, ensure that these are well presented. The purpose of engineering design calculations is not only to verify that a design is acceptable but also to provide clear documentation so that an engineer, not familiar with this project, could reproduce and verify your design calculations. Take note of the following in preparing your calculations:

­ Provide clear headings to indicate the purpose of each calculation. ­ It is strongly recommended that you use pencil for your calculations. ­ Clearly state and discuss the validity of all key assumptions. ­ Always explain what it is that you are trying to achieve. ­ Provide all key relations and provide references unless the relations are commonplace (e.g. “F = m × a” need not be referenced).

­ Define all notations and provide sketches if needed to ensure the reader knows unequivocally what you mean and that your notation is clear.

­ Provide free body diagrams. ­ Highlight key results.

An example of a well­presented design calculation is provided in Appendix I. NOTE THAT POORLY PRESENTED CALCULATIONS WILL NOT BE GRADED.

3.2 Design drawings

For every Phase (except Phase 1), each Team will develop an assembly drawing and/or component drawings that illustrate the key aspects of the design. It is recommended that drawings be done using Solid Edge. The assembly drawing will be a single cross­ sectional view of the gearbox in which all shafts, gears and bearings appear in side view or full section. All drawings must be handed in on the template Title Block, provided on the course web page. All drawings are to be in metric units, to a standard metric scale, and the scale is to be noted. Label all key components using a part number (in a circle) connected by a leader to the part. Include a bill of materials in the top right hand corner, or attached to the assembly drawing which provides the component names, part numbers, materials, and any other comments.

Drawings are to be plotted on 11” by 17” paper on the printer in Room 405 of McLaughlin Hall. Print credits have to be purchased at the Campus Bookstore and are 10cents for black and white, 75cents for color. It usually takes at least 24hrs for the credits to get logged into the system, so get them well in advance of something being due.

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3.3 Units of measure:

All calculations and drawings are to be done in metric units.

3.4 Phase submission format:

The submission that your team makes at the end of each phase MUST comply with the following format:

a) A title page with your team number, team member names, student numbers, and e­ mail addresses in the top right hand corner.

b) A table of contents c) Sections separated with tabs. d) All pages of the report should be numbered.

The report is to be stapled and put into a 9”x12” envelope. ALL DRAWINGS (11”x17”) ARE TO BE FOLDED IN HALF, BUT NOT STAPLED TO THE REPORT, and placed in the envelope as well.

The front of the envelope should display GROUP NUMBER, MEMBER’S NAMES, STUDENT NUMBERS, AND EMAIL ADDRESSES.

These are to be submitted in the MECH 323 dropbox on the 3 rd floor of McLaughlin Hall.

Bear in mind that your Team’s submission is one of many and that anything that you can do to make the markers’ work easier will be appreciated.

4 Evaluation

Each phase of the project is assigned a weight out of 40 total course marks (See Section 7.0). The basis by which marks are awarded will be shown on marking templates available on the course web page. Use these templates as a guideline to understand what the instructors and TA’s will look for when marking. Note that some minor changes may be made to these templates at the time of marking.

5 Teamwork

5.1 Team formation This project is to be done in Teams consisting of four students. The Design Project is demanding and it is important that your Team functions effectively. You will have two weeks to form your own team. If after two weeks you have not formed a team, the instructor will assign a team for you.

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5.2 Teamwork TA The Teamwork TA, Slav Florian (florian@me.queensu.ca) is available, upon request, for meetings with teams who need assistance with teamwork issues.

NOTE: THE TEAMWORK TA MAY BE CONTACTED AT ANY TIME DURING THE COURSE (BY ANY INDIVIDUAL OR ENTIRE TEAM) TO HELP DEAL WITH TEAM ISSUES. DO NOT HESITATE TO USE THIS RESOURCE, IT’S BETTER TO HAVE A ½ HOUR MEETING THAN WEEKS OF HEADACHES!!

6 Design assistance

Due to the large number of students in this course, the following system has been adopted for obtaining assistance in the course:

1) Come to the Tutorial/Lab sessions. During this time the instructor and TA’s will be available to answer questions.

2) Ask questions during lecture.

If you have a question that you have been unable to resolve by these methods, personal consultations can be arranged. To arrange for a personal consultation, send an e­mail to a TA or one of the instructors. In your e­mail, identify the problem and refer to the correspondence (as in (1) and (2) above) that you have already had on the issue. At least one day’s notice is required for personal consultations. To encourage you to undertake your work in a timely fashion, note that NO PERSONAL CONSULTATIONS WILL BE AVAILABLE ON THE DAY OF A SUBMISSION OR ON THE DAY BEFORE A SUBMISSION.

7 Summary descriptions of project phases

Team Formation Due: Friday January 17, Marks: 0/40

You will form your team of FOUR MEMBERS and report your team member’s names, student numbers and e­mail addresses to the teamwork TA by email. If the deadline is not met, a team will be assigned to those who have not formed a team yet.

7.1 Phase #1: Problem Definition for Gear Box design

Due: Monday January 30, Marks: 5/40

You will specify the key parameters and calculations, such as, diameter of the input pulley, in determining the required reduction ratio of the gearbox, and load on your input and/or output shafts.

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7.2 Phase #2: Spur Gear train design

Due: Monday February 27, Marks: 10/40

You will determine the initial gearbox using spur gears. The design of the spur gears will be based on the AGMA methods presented in the lectures. A technical drawing of the gearbox assembly is required.

7.3 Phase #3: Shaft design

Due: Monday March 13, Marks: 10/40

You will design the shafts based on the Gerber fatigue failure criterion for infinite fatigue life.

7.4 Phase #4: Bearing/Seal Selection

Due: Monday April 10, Marks: 15/40

Part I: Based on calculated reaction forces, you will select bearings to be used in your gearbox. For each of the two shafts in your gearbox, you will assess two (different) bearing configurations and then select the most appropriate alternative. You will use the SKF on­line catalogue to perform the bearing life calculations.

Part II: Using the CR Seals catalogue, you will specify appropriate seals for your gearbox. These specifications will be based on operating conditions and desired life. A technical drawing of your gearbox assembly is required for this phase, which includes the details of the bearing and seal configurations.

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8 Appendix I: Sample Manual Calculation