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'MACHINE ELEMENTS 2 Cams ? Cam is a link having an irregular fold or groove that im move interrogative sentence to a companion ? Cams are very classic and frequently occurring elements in many types of machines †oddly AUTOMATIC MACHINES ? Cams are the heart of much(prenominal) automatic devices as automatic devices as automatic machine tools, record changers, mechanically skillful calculators, cash registers, and many other devices. Types of Cams: gestures use for Cam Followers: ? The crusade of the companion is of base interest in the analysis of breathing cams or in the design of spick-and-span cams. It is easier to analyze the motion of cam accessorys if their motion is plotted as a graph often referred to as DISPLACEMENT draw A. Displacement Diagram B. efforts that are approximately commonly used: 1. supply speed (straight line) motion †UVM 2. easyx Harmonic communicate †SHM 3. Uniformly Accelerated motion (Parabolic Motion) †UAM or PM 4. Modified Uniform- upper Motion †MUVM a. curl regularity †MUVM-Arc b. Uniform Acceleration regularity †MUVM-UAM 5. Cycloidal Motion †CM A. Uniform Velocity Motion (Straight line of merchandise Motion)If the follower is to move with uniform velocity, its extirpation mustiness be the same for disturb units of clock. Its lift in the chemise diagram, therefore, is a full-strength LINE. Example 1: posture show up the transformation reaction diagram for a cam follower that is to have the following motions: abide 30O (at rest) cosmetic surgery 2 inches in 90O (uniform velocity) anticipate 30O clear 2 inches in 60O (uniform velocity) Dwell 150O B. Simple Harmonic Motion (SHM) As a occlusion moves around the circumference of a bunch with a constant velocity, its jutting on the diam of the carousel moves with simple harmonic motion.How to plot in the version diagram? Example 2: Lay show up the displacement diagram for a cam follower that is to hav e the following motions: airlift 2 inches in 120O (SHM) Dwell 30O drop curtain 1 inch in 90O (SHM) Dwell 30O flow 1 inch in 60O (SHM) Dwell 30O C. Uniformly Accelerated Motion (Parabolic Motion) ? A motion of uniform or constant speedup, often called parabolic motion because a graph of its equation ( s = at2 / 2 ) is a parabola. ? It is motion in which the displacement taking place in each successive interval of meter proportional to the square of the time.How to plot in the displacement diagram? Example 3: Lay tabu the displacement diagram for a cam follower that is to have the following motions: Rise 2 inches in 120O (uniform acceleration and deceleration motion) Dwell 30O Fall 1 inch in 90O (uniform acceleration and deceleration motion) Dwell 30O Fall 1 inch in 90O (uniform acceleration and deceleration motion) D. Modified Uniform Velocity Motion a) Arc method acting: This method consists merely in introducing arcs at the antecedent and at the end of the displacement period. The surface of the arcs is arbitrary, but they are usually careworn with a radius equal to 1 half the displacement. The arcs are drawn low to an indefinite length then a straight line is drawn topaz to both arcs. b) Uniform Acceleration Method: This method consists in introducing short periods of uniform acceleration or deceleration at both ends of the displacement period. D. Cycloidal Motion ? If a circle rolls along a straight line without slipping, a point on its circumference traces a yield that is called a cycloid. How to plot in the displacement diagram?In the inscribe beneath shows how such motion is laid out in a displacement diagram. Line AB is drawn and is extended to both(prenominal) point such as C. A circle is drawn at C whose circumference is equal to the displacement s or whose diameter is equal to s over constant pi. The circumference of this circle is divided into a event of parts corresponding to the physical body of divisions along the plain scale. Th e points around the circle are intercommunicate to the vertical center line of the circle and then parallel to the line AB to the corresponding vertical lines in the displacement diagram. ———————- [pic] [pic] [pic] [pic] [pic] [pic] In this construction, it should be noted that the diameter of the semicircle is equal to the follower hop on and that the number of divisions around the semicircle agrees with the number of divisions along the time axis (angle of cam rotation). [pic] [pic] The figure at the left shows the displacement, s of a falling object compares with arbitrary time units [pic] a) First method (Figure @ the right)In laying out this type of motion in a displacement diagram, a given displacement is divided into two halves †the first half is uniformly accelerated, and the second half is uniformly retarded motion. It is therefore, necessary that the even distance involved in the total displacement be divided into an even number of divisions. [pic] b) Second Method (Figure @ the left) Figure as shown, shows an alternative method of constructing this type of motion. In this case, the half displacement is divided into equal sized divisions corresponding to the number of horizontal divisions. [pic] [pic] [pic] [pic]\r\n'