Applications of graphical design, Mechanical shuttle

Clarence McChristian

Parkfield Dr

Austin, Texas 78758

United States

Email address: [e-mail]

Telephone no: 01 512 837 2572

Mobile no: 01 512 554 3969

The school year is over for NEISD in San Antonio. I am seeking an AutoCAD

job in your area. My work experience includes Aerospace, Avionics, and Architectural;

residential and commercial, Civil/Survey one year, Mechanical and sheet metal.

APPLICATIONS OF GRAPHICAL DESIGN, Mechanical Shuttle

This application is used to convert rotational motion into controlled linear motion. Start creating a scale drawing of the linkage components. The linkage is drawn to show the end point “P”, which is used as the zero point for plotting the travel versus the degrees of revolution.

DESIGN SPECIFICATIONS:

I Index = 90 in. Index Time = 1.5 SEC. Load Wsubs = 2,000 LB Friction f = 0.2

Since rotation is constant at one revolution per three seconds, the degrees of revolution can be converted to time.

Graphical determination of velocity and acceleration of the mechanical handling shuttle by differential calculus.

R1 = Length of Drive Crank P = Point Accelerated

R2 = Length of Driven Crank S = Displacement of P

L = Effective Lever Arm T = Torque required to Accelerate Load

Fa = Accelerating Force theta = Drive Crank Angle of Rotation

Fc = Resultant Acceleration Force Phi = Drive Crank Angle to Perpendicular

Fo = Retarding Force Omega = Drive Crank Angular Velocity

The drive crank R1 is revolved at 30-degree intervals, and the distance that point “P” travels from its end position is plotted on the graph. This determine the ordinate scale of the derivative grid by estimating the maximum slope of the given data curve, which is found to be a little less than 100 in/sec. A convenient Scale is chosen that will be used for the derivative curve; the maximum limit is 100 units. A slope of 40 is drawn on the given data curve; this will be used in determining the location of pole “P” in the derivative grid. From point 40 on the derivative ordinate scale, we draw a line parallel to the known slope, which is found on the given grid. Point “P” is the point where this line intersects the extension of the X-axis.

Shuttle used to move automobile parts on an assembly line.

A series of chords are drawn on the given curve to approximate the slope at various points. Lines are constructed through point “P” of the derivative scale parallel to the chord lines of the given curve and extended to the ordinate scale. The points thus obtained are then projected across to their respective intervals to form vertical bars. A smooth curve is drawn through the top of each of the bars to give an average of the bars. This curve can be used to find the velocity of the shuttle in inches per second at any time interval.

The construction of the second derivative curve, the acceleration, is very similar to that of the first derivative. By inspecting the first derivative, we estimate the maximum slope to be 200 in./sec/sec. An easily measured scale is established for the ordinate scale of the second derivative curve. Point “P” is found in the same manner as the first derivative.

Chords are drawn at intervals on the first derivative curve. Lines are drawn parallel to these chords from point “P” in the second derivative curve to the Y-axis, where they are projected horizontally to their respective intervals to form a series of bars. A smooth curve is drawn through the tops of the bars to give a close approximation of the average areas of the bars.

NOTE: A minus scale is given for the acceleration curve to indicate deceleration.

The maximum acceleration is found to be at the extreme endpoints and the minimum acceleration is at 90-degrees, where the velocity is the maximum. It can be seen from the velocity and acceleration plots that the parts being handled by the shuttle are accelerated at a rapid rate until the maximum velocity is attained at 90-degrees, at which time deceleration begins and continues until the parts come to rest.

Дата добавления: 2015-10-31