Design Project SP22 ENGR-100 Design Project Spring 2022 Overview Your assignment is to design a gearbox that will allow a motor to lift a 120lbf load 60ft vertically in 30 seconds using a rope and...

assignment attached.


Design Project SP22 ENGR-100 Design Project Spring 2022 Overview Your assignment is to design a gearbox that will allow a motor to lift a 120lbf load 60ft vertically in 30 seconds using a rope and winch system. See the rubric in Brightspace for grading info. Key Dates: ● All materials must be submitted in Brightspace by 7PM on Monday, April 18th. Deliverables: 1. CAD Model: at minimum, a basic “crayola” CAD model with gears and a backing plate. To earn full credit, include additional detail beyond the bare-minimum requirements. 2. Overview Sheet: a single typed page that contains, at minimum: a. The overall gear ratio for the gearbox b. The calculated output torque for the gearbox c. The calculated rope linear speed d. The part number, cost, power, speed, and continuous torque for your motor e. Your selected winch diameter f. The following information about each of the gears in your gearbox i. Tooth count ii. Diametral pitch iii. Pitch diameter iv. Material v. Tooth stress g. Total cost of the parts from McMaster for your gearbox (motor and gears) h. An image of your gearbox, with the overall dimensions and gear tooth counts labeled. 3. Supporting Documentation: copies of all your math used throughout the design of your gearbox. Be sure to clearly label your steps and work, so that it is obvious what is being done, and which iteration the math is for. If you use spreadsheets, include those files in your Brightspace submission. Note: part of your project grade will be based on the accuracy of the calculations for your final design. Design Requirements: As stated above, the gearbox must allow a motor to lift a 120lbf load 60ft vertically in 30 seconds 1. The output torque of the gearbox should be at least 20% greater than the load torque. For your calculations, use the “continuous torque” rating from the motor product page. a. Assume 95% efficiency for 2 gears, or 92.5% for 4 gears b. Note: having more torque than needed is OK. 2. The output speed of the gearbox should be such that the rope speed is within ±0.5ft/s of the necessary speed. For your calculations, use the maximum speed rating from the motor product page. a. Note: this means your system has both a minimum and maximum speed. 3. The tooth stress on each gear must be less than 1/3rd of the yield stress for the gear material: a. Brass: 55000PSI b. 1117 Carbon Steel 68900PSI c. 1144 Carbon Steel (Hardened): 89900PSI1 d. 1020 Carbon Steel 60900PSI Available Materials: ● The available winch diameters are: 1in, 1.5in, 2in, 2.5in ● You may use any of the motors listed here: https://www.mcmaster.com/motors/face-mount-ac-motors/electrical-phase~single/voltage ~115v-ac/motor-frame-size~nema-56c/motor-enclosure-type~open-dripproof-odp-/ ● You may use any of the 20 degree gears listed here (don’t worry about gear shaft size): https://www.mcmaster.com/gears/metal-gears-and-gear-racks-20-pressure-angle/compo nent~gear/system-of-measurement~inch https://www.mcmaster.com/motors/face-mount-ac-motors/electrical-phase~single/voltage~115v-ac/motor-frame-size~nema-56c/motor-enclosure-type~open-dripproof-odp-/ https://www.mcmaster.com/motors/face-mount-ac-motors/electrical-phase~single/voltage~115v-ac/motor-frame-size~nema-56c/motor-enclosure-type~open-dripproof-odp-/ https://www.mcmaster.com/gears/metal-gears-and-gear-racks-20-pressure-angle/component~gear/system-of-measurement~inch/ https://www.mcmaster.com/gears/metal-gears-and-gear-racks-20-pressure-angle/component~gear/system-of-measurement~inch/ Math Tips ● Start by using the linear power equation to determine the motor HP rating you’ll need. ● The load torque is based on the load weight and winch radius (note radius vs diameter) ● When determining the gear ratio for your gearbox, remember to check both the output torque and output speed at your chosen ratio ● For tooth stress, meshing gears have the same tangential load (WT) and tip speed (V). ● If you are using a 2-stage gearbox (2 pairs of meshing gears): ○ The tangential load (WT) and tip velocity (V) for the last gear (N4 in diagram on the next page) should be calculated using the gearbox output torque and speed. ○ The tangential load and tip speed would then be the same for the 3rd gear (N3). Equations ● ?????? = ????? * ???????? ● ?????? ????? = ????? * ???????????? ● ?????????? ????? = ?????? * ??? * 2π60 ● Gear ratio for single pair of gears: ????? = # ?????? ????ℎ# ??????? ????ℎ = ? 2 ? 1 ● Gear ratio for a 2-stage gearbox: ????? = ? 2 ? 1 ( ) * ?4? 3 ( ) ● Gearbox output speed: ????? ??? = ????? ?? ????? ● Gearbox output torque: ?????? ??? = ?????? ?? * ????? * ?????????? ● Tooth stress (V in ft/min, Pd is the pitch, not the pitch diameter) σ = ? ? *? ? ?*? * 1200 + ? 1200