PART A: REPORT (TO BE TURNED ELECTRONICALLY AS A .PDF FILE)
Page 1: This cover page
Page 2: Detailed Drawing of your shaft designs (one for the bottom and one for the top) like the one I handed out in class that shows all of the dimensions, locations of bearings, keyways, shoulders, radii, etc. In the bottom right hand corner, put your name.
Pages 3-5: Type written report: 3 pages. 12 pt Times New Roman Font with double spacing and 1.0" margins all around. (Use of tables is encouraged to summarize your design). The following sections must be included:
a. Executive Summary
b. Problem Statement
c. Problem Solution w/assumptions
d. Design Summary: summarize all components of your design
e. Conclusions and Recommendations
Pages 6-end: Appendix of Design Equations: This is where you write out your diagrams, free-body diagrams and solution equations and state your assumptions for each part of your design. You will use these equations in Excel. It is as long as you need it to be and should be hand written neatly.
PART B: EXCEL DESIGN
One worksheet should be input parameters. A second worksheet should be intermediate calculations/results and a third worksheet should be the output of your design.
Design of a Shaft for a 30 HP, 3600 RPM Electric Motor
Assignment
You are a design engineer. It is your responsibility to design and specify rotating machines and drivetrains for a variety of applications. A customer is proposing to manufacture 30 HP, 3600 RPM motors in mass quantities. The electrical design for the motor has been completed and the figure on the next page shows the electrical armature which is a cylinder of high magnetic permeability steel attached to a steel carrier on its inner diameter and two steel end caps that complete the assembly. The dimensions of the armature assembly are given in Figure 1. The armature assembly is attached to the shaft at its inner diameter using an interference fit. The motor is to operate in a horizontal configuration, meaning that the shaft is parallel to the ground (orthogonal to the direction of gravity).
It is your job to design the shaft, coupling key, fan key and ball bearings for this application. Assume that the armature assembly design is fixed and will survive any of the loads. In particular you are to design the shaft geometry, select a set of ball bearings for the application and select and design the key and keyway for a coupling that would be placed on the end of the shaft that protrudes from the motor housing (stub shaft) and for the fan that is attached at the other end of the motor shaft internal to the motor housing. You are also required to make sure the critical speed of the shaft/armature assembly is above the operating speed of the motor by at least 10%. Figure 2 shows an example drawing of a simple motor as an example. Shaft geometry includes all shoulders and radii, bearing locations and the interference fit between the shaft and the inner diameter of the armature assembly. For the interference fit, be sure to specify both the shaft outer diameter and the armature inner diameter.
The loads that you should consider are: 1) the constant force due to gravity (consider the armature and shaft - neglect the coupling, ball bearings and fan as they are small by comparison), 2) a constant torque equal to 5 times the torque at the operating speed (1800 rpm) which is the approximate torque seen by the shaft at start-up and 3) the dynamic unbalance force assumed to occur in two balancing planes (see Figure 1). You are to use the attached ISO specification for two plane balancing to compute the residual unbalance in the two planes and assume that the unbalance forces occur either in the same direction or 180 degrees out of phase, whichever creates the worst case force on the shaft. Not given in that handout is the equation to compute the force at each balance plane due to residual imbalance.
Attachment:- project_fall.rar