advanced mechanical design
Edith Cowan University School of Engineering Advanced Mechanical Design Major Assignment Skip Bin Truck Actuator Gearbox Design Due Date: 5:00pm 28th September 2020 (Design Report and load calculations) Due Date: 9:00am 26th October 2020 (Overall report) Submission: Hardcopy with a completed ECU coversheet. Submit to Engineering Office, building 23. Note: Peer assessment considered during marking, please include if you feel there is workload disparity Your team’s (group of 5 students maximum) task is to design an entire gearbox assembly that is mounted to a skip bin truck and drives a threaded-rod linear actuator to raise and lower the skip bin, as illustrated in Figure 1 below. The linear actuator gearbox is driven by a hydraulic motor. The gearbox then rotates a nut that extends or retracts the linear actuator threaded rod. The hydraulic motor (TB0036) specifications are provided in the attached documentation. The overall gearbox design should include, load calculations, gear design, shaft design, fastener sizing, bearing selection, gearbox housing design, the size of the linear-actuator threaded-rod as well as any other accompanying components such as seals and clips, etc. to ensure a completely operating gearbox. Fastener calculations are only required to justify the size of main structural bolts used in the design (and not every bolt). It is a design requirement that any rotating structural components in the design are located by rolling element bearings. Figure 1. Schematic of Skip Bin Truck during unloading: Truck, bin, linear actuator and mechanism Linear Actuator Chains Bin Bin Arm Mechanism Truck Ground Loading Unloading The bin mass including bin and payload is 1tonne, where the bin is 2.5m long, 1,5m wide and 0.9m high. When fully loaded the bin centre of gravity (CoG) height is 490mm from the base of the bin, and located centrally from a side view. The bin rests on the truck bed once loaded, where the truck bed is 900mm from the ground plane. At a minimum range of travel, the actuator length should vary from 1m when the bin is loaded, to 1.77m when the bin is unloaded. Dimensions of the bin load-and-unload mechanism are detailed in Figure 2 below. Note: there is a bin arm mechanism either side of the bin, and each bin arm is operated by a separate, identical linear actuator. The bin is suspended from the bin arm mechanism using chains. Your load analysis of the loading and unloading phases of operation should detail any critical assumptions that are made in order to complete your calculations for a safe operation. To improve overall productivity, the bin load and unload speed should be as high as possible. Hydraulic motor (TB0036) and gearbox are attached to one another, where the gearbox is then mounted to the truck bed (as illustrated in Figure 1). As a result, the gearbox and hydraulic motor should be designed as one single device that is then attached to the mast, where the gearbox is a structural member that ensures attachment of both the linear actuator and hydraulic motor to the truck bed. No details of the truck bed are provided, hence you can specific where you would like to mount the gearbox to the truck bed with provisions to do so. Rotating motion between components should be isolated with rolling element bearings that are adequately sized. There is no requirement for coaxial alignment between the hydraulic motor and linear actuator, this is your choice. The truck has a hydraulic power supply that offers a maximum of 100 Bar oil pressure and a maximum of 50 L/min oil flow rate. Along with the gearbox design, please provide any operating conditions (such as hydraulic performance) in order for the operator to maximise productivity. The truck is designed to operate as reliably as possible to avoid any downtime, however, this must be within reason to avoid unnecessarily expensive components and the entire gearbox should not need servicing for a minimum of 10,000 hours. Figure 2: Dimensions of skip bin arm mechanism The assignment deliverables for the design are as follows: 1. A set of design documents for the assembly: A design report that details (15%): Product design specification Manufacturing details (including processes, off-the-shelf components, required treatments, etc.) An analysis report that covers (45%): Load calculations (prior to failure analysis) Stress and fatigue calculations for life analysis Failure analysis calculations of component(s)/assembly where applicable Finite Element Analysis of structural gearbox housing A set of manufacturing drawings – fully dimensioned of all parts ready for manufacture (Note: this excludes the motor, gear tooth profiles and bearings) (10%) SolidWorks 3D model (or equivalent CAD model that can be opened within SolidWorks) of the complete actuator assembly and components. Printed (hardcopy) images of the components in your design are required along with electronic files of the parts and assemblies (15%) 2. Presentation: A 5-minute presentation of your group’s design to the class during the final lecture (5%). 3. Teamwork: Cooperate as an effective team with suitable load sharing (5%) 4. Report: All aspects for a quality report, such as grammar, referencing, presentation, etc. (5%) Note: The design report and load calculations are due 5pm 28 September 2020. The overall report is then due 9am 26 October 2020. The written component (excl. drawings) of the design report should not exceed 10 pages, any content beyond 10 pages will not be considered in the mark. The analysis report should not exceed 30 pages, any content beyond 30 pages will not be considered in the mark. Notes and Assumptions: I. The gearbox should be serviceable II. The gearbox should include oil fill and drain locations III. This gearbox should be designed for a heavy industrial application IV. The final design should be a complete ready-for-manufacture design Dr. Ferdinando Guzzomi Email:
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