Reference no: EM132940134

MECH215 Mechanical Engineering Design - University of Wollongong

Project Brief 2020 - Geared Drive System Design

This assignment is individually assessed. You are required to design various elements of an overall geared drive and to produce the resulting Creo Parametric generated 3D models and associated engineering drawings. You must record your design work contemporaneously on design sheets and maintain your individual reflective journal (diary with reflections) using the templates supplied.

The work is divided into discrete tasks and you will submit completed tasks progressively for review and assessment. Prior to commencing each task you will need to complete the associated topic learning activities utilising the study guides and quizzes provided for that purpose.

You will work in a team of 2 people, with clearly defined responsibilities for particular parts of the design. You will maintain an interest in the overall design.

OVERVIEW

Purpose:
The purpose of this assignment is to provide you with the opportunity to undertake typical mechanical design tasks within the context of a mechanical system. You will be supported in this by the topics you study as part of this subject.

Overall Task:
The design of a geared drive system is required. The system is a motor-driven geared drive incorporating a single-stage reduction gearbox. It is to drive a belt conveyor. Some prescribed aspects of the design problem as stated and the design provided are not necessarily relevant to a practical case.
You are supplied with a Project Folder that you download from eLearning, containing Creo Parametric 5.0 part models for the upper and lower gear cases as well as the following parts:
Input (1st motion) shaft assembly
- Shaft with integral pinion gear
- Bearings and associated components
- Seal
- Endcaps
Output (2nd motion) shaft assembly
- Gear (without bore features)
Your team will be provided with specific design parameters for the drive. You will need to modify the parts models provided to match with the parameters specified.
Gearbox as supplied and with top hidden

Tasks:
You will be required to complete the design of a geared drive that will be used to connect an electric motor (energy source) to a load. To do this you will need to design or select a:
0. Induction motor suitable for the task, then considering the motor characteristics and the load:
1. Output shaft assembly including the shaft, bearing arrangement and selection; endcap and screws, and seal based on the nominal size of the supplied gear bore; modifying the upper and lower gear-casings to accommodate your design.
2. Coupling for the output shaft.
3. Conduct both an analytical and numerical (FEA) examination of the stresses induced into the input and the output shaft making suitable assumptions and geometry simplifications.
4. Gear-casing joint design including dowels; bearing housing bolts and flange bolts.
5. Baseplate that allows for the relative location and support of the gearbox, motor and connecting flexible drive.
6. Hold-down bolts for the gearbox and for the motor.
7. Flexible drive (belt or chain) connecting the motor to the input shaft of the gearbox, modifying the input shaft.
8. Tensioning device for the flexible element, incorporating a bespoke spring.
9. Produce an assembly model.
10. Produce General Arrangement, Assembly and Part drawings and assembly drawing that will enable the manufacture of the geared drive.
Tasks need to be allocated amongst the team members so that all topics are covered by each team member and responsibility is taken for specific parts.
Note, unless specified otherwise, proprietary items are to be used, where possible.

Set out your work methodically on design sheets utilising the task statements as headings. For each task, set out: 1. Task statement; 2. Inputs and data, 3. approach, 4. Options where relevant; 5. Analysis;
6. Selection; 7. Verification and 8. Conclusion. The use of spreadsheets is strictly prohibited.

There are 2 parts to the submission for each task:
1. Workbook: Submit to assignment link provided on eLearning.
a) Title page and table of contents.
b) Prints of relevant Part drawings (Note part drawings for proprietary items must not be drawn or provided: especially bearings; bolts; washers; belts or chains; motors; couplings. Those will however need to feature in relevant general arrangement and assembly drawings.)
c) Prints of relevant General Arrangement and Assembly drawings where relevant
d) Design sheets for each of the tasks;
2. Creo Parametric 5.0 files: ZIP file: 200Mb maximum file size, including all: part; assembly and drawing files used for this assignment Submitted through a separate link provided on eLearning. Ensure no erroneous files are included.

TASKS
Note that the order of design prescribed has been designed to balance out topics covered in the program. The order may not be a strictly logical approach, depending on the situation faced.

1. ENERGY SOURCE SELECTION For this task, work as a team.
1.1 SELECT A MOTOR
Given the required torque, speed and speed ratio required for your specific requirements, select an appropriate motor size from the catalogue provided.
1.2 DETERMINE THE APPLIED MOTOR CHARACTERISTICS
Obtain the Torque-Speed curve for the selected motor and determine the motor's operating speed and start-up torque and maximum torque assuming the motor is started direct-on-line (DOL).
SUBMIT YOUR DESIGN SHEETS THROUGH THE LINK PROVIDED FOR THIS TASK

2. OUTPUT SHAFT ASSEMBLY DESIGN
For this task, work as a team but allocate responsibilities for each section between you. Each person is to use separate and clearly identified design sheets for their parts.
2.0 ESTABLISH YOUR SPECIFIC GEAR SET DETAILS
Setting out your work methodically on design sheets: determine the required pinion and gear dimensions from the gear details provided to you separately in the Specific Design Parameters document provided to you. At this stage you may edit the definition and dimensions of the Creo Parametric 5.0 gear models provided to match your requirements. Note the gear tooth sections have been modelled separately and assembled to the remainder of the gear for convenience. Alternate approaches may be used.
2.1 SET OUT THE SHAFT DESIGN PROBLEM
Develop the problem statement and sketch out a schematic of the shaft with suitably sketched representation of the situation and all relevant variables and data identified.
2.2 SELECT A COUPLING FOR THE OUTPUT SHAFT
Establish 3 options for suitable coupling types given that the gearbox is to drive a belt conveyor in a mine application. Choose one of these types and select a specific coupling from a catalogue.
Choose a suitable fit for the coupling.
2.3 SHAFT FORM DESIGN, PRELIMINARY SIZING
Estimate the shaft size at the gear using the approximate formula:

d = 3.4 3fTNAs

where TNAS is the maximum torque applied to the shaft in Nm and is the shaft diameter in mm. Design of the keys and keyways required to couple the gearwheel, and to coupling the output coupling half: utilising the British Standard guidelines to determine the profile and strength considerations to determine the required length for the key. The fit for the gear should be H7/r6.

Determine gear loadings applied to the shaft by identifying the parameters for your gear-set and calculating the tooth forces.

Select the bearings for the shaft. Establish suitable bearing types and arrangement: a. establish the requirements for these bearings; b. identify 3 options for bearing types and arrangements; c. select what you consider to be the best option, providing the logic leading from the situation to your decision. Select specific bearings by first determining the gear forces and resulting reactions at the bearing locations. Now identify the relevant features of the bearing shaft journal and housings, including the endcaps and record the relevant bearing data: fits, geometry and surface finishes required. Bearing selection must be done manually, based on the ISO basic life rating. You are required to use SKF Bearings. Select a suitable seal.

Note you need to be prepared to iterate given that the span of the shaft depends on the width and position of the bearings thus affecting the forces applied to the bearings.
2.4 MODIFY GEARBOX COMPONENTS
Model or modify the resulting parts and assemblies in order to create your gearbox assembly. SUBMIT YOUR DESIGN SHEETS THROUGH THE LINK PROVIDED FOR THIS TASK ON ELEARNING.

3. CHECK STRESSES INDUCED INTO THE SHAFTS
For this task, allocate one of the shafts to each person in the team.
3.1 ANALYTICAL ANALYSIS
Calculate the von-Mises (equivalent) stress and Factor of Safety for fatigue failure, at the maximum torque, using the modified Goodman criteria for the critical section: advised to be the outboard (coupling) end of the gear journal. For this you are required to investigate 2 different materials: AISI4130 Q&T 650C and AISI4340 Q&T 315C. You must use the properties for these materials as defined in the text. From your analysis, specify the shaft material and finalise the shaft details.
For this analysis you are required to use the basic theory as set out in Chapter 5 and 6 of the text. You are forbidden from using the approach given in Chapter 7 or other direct shaft analysis algorithms.
3.2 NUMERICAL ANALYSIS
Perform a FEA of the output shaft designed and compare the output to those you obtained from your analytical results. Include a brief discussion on the reasons for the differences in the results, noting that it is not expected that they will match. Suggest any actions that could be taken to reduce the stress in the shaft but do not redesign the shaft.
Your design sheets should include: the inputs to your FEA (model, forces, joints used, meshing strategy) and the output: picture of meshed shaft; comparison of the bearing reactions and coupling torque to the theoretical values; picture of the shaft with von Mises (equivalent) stress field.
Take care to identify the maximum stress indicated in the FEA and to consider which analytical results should be compared with the FEA result.
SUBMIT YOUR DESIGN SHEETS THROUGH THE LINK PROVIDED FOR THIS TASK

4. COMPLETE THE CASING AND MOUNTING ARRANGMENTS FOR THE GEARBOX
For this task, allocate 4.1 to one person in the team and 4.2 to the other person.
4.1 DESIGN THE FASTENERS and WELDS FOR THE CASING HALVES
Select bearing housing bolts or screws and closure bolts or screws and design the welds for the casing.
4.2 DESIGN THE BASEPLATE INCLUDING HOLDDOWN BOLTS
Design a baseplate, by selecting appropriate structural sections and designing the welds, that will support the motor and gearbox, including allowance for a flexible drive connecting them. Include features allowing appropriate adjustments.
SUBMIT YOUR DESIGN SHEETS INDEPENDENTLY THROUGH THE LINK PROVIDED FOR THIS TASK

5. DESIGN THE CONNECTION BETWEEN THE MOTOR AND THE GEARBOX
For this task, allocate 5.1 to one person in the team and 5.2 to the other person.
5.1 SELECT AND DESIGN AN APPROPRIATE FLEXIBLE DRIVE ARRANGEMENT
For the ratio required select an appropriate flexible drive and size its components. Design the interfaces with the motor shaft and the gearbox input shaft.
5.2 DESIGN A BESPOKE TENSIONING DEVICE FOR THE FLEXIBLE DRIVE
Design a tensioning device for integration into the drive, utilising a compression spring as the active element.
SUBMIT YOUR DESIGN SHEETS INDEPENDENTLY THROUGH THE LINK PROVIDED FOR THIS TASK

6. FINALISE AND COMMUNICATE YOUR DESIGN
Revise the design and submit. Make changes to the models provided as you see fit. This task is to be completed by each member of the team independently.
6.1 PART DRAWING FOR THE OUTPUT SHAFT
Produce a detailed shaft drawing-sheet from your shaft model using Creo Parametric such that the shaft can be manufactured from this drawing. Ensure that all details are provided such that the shaft could be manufactured from the drawing: include all dimensioning and geometric tolerances.
6.2 ASSEMBLY DRAWING
Produce an assembly drawing for the gearbox.
6.3 GENERAL ARRANGEMENT DRAWING Produce an assembly drawing for the gearbox.
6.4 PRESENT YOUR DESIGN
Record a 2 minute video answering the questions provided separately concerning your design approach and analysis processes and their outcomes.

SUBMIT YOUR DRAWINGS AND VIDEO INDEPENDENTLY THROUGH THE LINK PROVIDED FOR THIS TASK

Attachment:- Mechanical Engineering Design.rar