All analyses were completed in the documents below. The following sections will refer to these documents when referencing calculations.
The rotational-to-linear mechanism operates in the horizontal plane with a the driving motor set below the system. A rugged baseplate provides support for the system.
The linear slider mechanism translates the rotational motion of the shaft through a connecting rod to a linear motion. It employs linear bearings guided by rails.
The adjustment mechanism is a friction locking device. Two bolts located on the upper slider clamp with two T-blocks located in the notched bed of the device. When torque is applied to the screws, the entire system is drawn together as the T-blocks come in contact with the upper groove. There are four major friction locking surfaces.
The connecting rod is the true medium between which rotational motion is converted to linear. It employs ball bearings that rotate about two press-fit pins, one located on the adjustment mechanism and the other located on the linear slider.
The recommended frame design significantly lowers the current system's size envelope. Additionally, a flange attachment region has been added for mounting improvement for the vertical conduit and luminaire.
Lubrication of the crankshaft system is much simplified from the scotch yoke design, which is the major reason for the move to the crankshaft style mechanism.
Kinematic Analysis of Crankshaft
This analysis was adapted from Dr. Stephen Boedo's Single-Cylinder Engine Dynamic Analysis. Our analysis was a simplified form that treated the piston as a general linear slider and replaced any pressure forces on the piston with the 800lb force from the vertical conduit deflection.
GFEM of the adjustment mechanism is shown below.
Drive Shaft AnalysisThe recommended motor for this system outputs a 5/8" shaft diameter. Using variable diameter locking collars, the actual drive shaft of the system is chosen as 1" to aid in the robustness of the system. Two flange-type bearings mounted on either side of the system baseplate provide lateral support for the shaft. It is connected to the rotating disc and adjustment mechanism by a flange collar on the upper side of the baseplate. The shaft is keyed along its entire length.
Analysis of Miscellaneous ComponentsThe threaded extension rod is the rigid connection between the slider mechanism and the vertical conduit. It is clamped to the slider in two places and is to be threaded into the collar located on the conduit to complete the connection.
The connecting rod is a simple rectangular design with ball bearings on either end. The entire part will be machined from one solid piece of steel and will be bolted together on either end to provide the force to keep the bearings in place. GFEM analysis of the component is shown below.
GFEM was completed on the connecting rod as shown below:
Bolt Strength AnalysisThe system was designed in such a way that the bolts would be taking the majority of the load. This builds in a safety factor so that there is a better chance that, if failure were to occur, it would be the bolts that were the issue and not the more expensive and important machine components.
The following table details the major bolt locations in the system and their associated factors of safety. Note that the location of these calculations are denoted by section and page number as well as an equation number on that page. These locations are to be found in Appendix A, a PDF of which can be found at the top of this page.
Motor SelectionFollowing Customer Need CN3, the desired motor was to be a 3-phase, 240V AC motor. Analysis was completed on the system at steady state, yielding a maximum required horsepower of 0.41HP. A 1HP motor was then decided upon. A start-up period analysis followed, where the inertia of the system was included. Assuming under a minute start-up to 2000RPM, a motor torque was calculated and referenced to the Reliance Electric torque-speed curve. The recommended motor was chosen from Baldor and is also shown below.
Bill of Material (BOM)
Test PlansThe testing of this system will consist only of verifying the displacement (or stroke) of the crankshaft mechanism. A dial gauge will be used for measurement purposes. The adjustment mechanism will allow for fine-tuning of the system if the initial displacement is not exact.
Risk AssessmentThe below assessment has been updated to reflected actions taked since the System Design Review to mitigate risk. Additionally, new risk areas have developed.
Senior Design II Preliminary Schedule
Detailed Design ReviewDetailed Design Review to be completed at Cooper in Syracuse on Thursday, February 21, 2013 at 11:30am.
Full transcript of this meeting to follow.