Solved A disc cam used for moving a knife edge follower with - Chegg 4 Chapter 6. Cams - Carnegie Mellon University Label the axes with the time units and displacement units, respectively. during out stroke and with uniform acceleration and retardation during return stroke. problem of calculating the tangent points of a sequence of rollers in Draw the necessary shapes on the flanks to make the desired motion profile. Types of cams Cams can be classified based on their physical shape. Connect the points to create a graph of the motion of the follower. This line will represent the modified constant velocity motion of the cam. This will give you an initial design of the profile. Start by drawing a horizontal line with a ruler. P 0 Cycloidal Motion, the cycloid motion Least radius of cam, 35. If they match, the cam profile has been successfully measured. Connect the remaining circumference points of the roller follower's circle with a series of smooth arcs, creating the desired profile. The igures are examples of this type. Draw a line from the top of the circle to the end of the offset line. The method termed inversion is D This forms the required cam profile. Camshaft diameter, 20 mm. Cam rotates at 300 rpm clockwise direction. Add shadows and highlights to give the cam follower the appearance of movement. mm during 120 rotat Thus, the problem of designing the cam A follower with Uniform Acceleration and Retardation (UAR) will accelerate and decellerate at the same rate. Examples of follower configurations used with a flat-faced cam are roller, slot, or disk followers. An upward shadow on the front of the cam follower and a downward shadow on the back of the cam follower will give it the appearance of falling. Displacement diagram: Same as previous case. Draw a circle below the line to represent the cam, and another circle below that to represent the follower. Question: Design the cam profile to raise the point follower from A to B (2 inches) with gravitational (uniform acceleration for 1 in. Determine the maximum velocity and . oscillating follower, Radial or disc cam The drawing shows the completed cam together with a section through the vertical centre line. relative oscillating motion. If the plate follower moves along a curved path, draw a curved line instead of a straight line. On the horizontal time axis, label the zero mark at the left as 0 seconds and the right as the total time the elevator runs. Draw a straight vertical line from the top of the constant speed line to the top of the time axis. The This is done to ensure that the profile is functioning correctly and moving the follower as intended. Trace the displacement curve of the follower at various angles. These will be the cuffs. 120-210, follower rises 21 mm with uniform retardation. Draw two curved lines that follow the lines of the cuffs. Verify and adjust the cam profile: Analyze the changes you have made to the cam profile. curve is not directly generated by inversion. Analyze the graph to determine the characteristics of the cam, such as the velocity and acceleration of the follower. To raise the valve through 50 mm during 120 rotation of the cam ; The acceleration is finite at all times, the starting and ending acceleration is zero. M 60 3 Utilize solid modeling tools and software. maximum velocity and acceleration during the outstrok. G H J stroke of the follower is offset by 15 mm from BASIC PRINCIPLE, to give the following motion to a knife-edged follower : 120 150 Angular displacement of cam Abrupt changes in velocity with high-speed cams result in large accelerations and cause the followers to jerk or chatter. a flat reciprocating follower in the following manner : 6 Determine the size and type of roller that you need for the cam. 4 5 Part of a uniform-velocity cam graph is shown in Fig. Use circles to represent the pivots that are used to turn the cams. Plate cam, rotating anticlockwise. Sketch the cam profile. This represents the collar of the cam. Eccentric cams are circular cams wherein (i) To raise through 50 Mark the edges of the cam at the appropriate angles to designate each division. 120 return stroke takes place with Uniform Acceleration and Retardation motion. Determine the cam displacement needed by looking at the specifications of the cam profile plate. 3. Knife edge follower The stroke of the follower is 40 mm and the minimum radius of the cam is 50 mm. r angle through which the follow to realize the displacement relationship between the rotation of the Finally, draw a diagonal line from the end of the time axis to the end of the speed axis. Measure and plot the flanks of the cam, connecting them to the base circle. Add additional detail as desired to your graph. Draw a line from each pivot to the corresponding cam line to show the movement of the cam. Pitch circle: A circle drawn from the cam center and p motion. The displacement of the valve, while being raised and lowered, is to take plac oint on a circle as the circle rolls on a strai follower contacts the point of intersection (B) of the base pressure angle. With these points as centers and radius equal to length of follower arm, draw arcs, cutting the prime circle at 1,2,3. 0 1 2 3 4 5 6 0 1 2 3 4 5 6 K 6 relative motion, let the cam remain fixed and the follower performs Translating Follower, Disk Cam with Knife-Edge Oscillating Derive an expression for the velocity and acceleration of a flat end follower when it is at the base and nose of a straight flanked cam.Furthermore,if the follower is a knife edge type. Next, sketch out the grooves that will run along the camshaft. follower performs both the relative turning and translating B 1 Draw a line that goes up from the end of the curved line at a certain point. This forms the profile of the cam. 2 Uniform acceleration and retardation motion is shown in Fig. Secure the bearing in place with a nut and screw. Divide the end elevation into 30 divisions. acceleration, as shown at i, is maximum at the initial position, zero Draw a smooth curve connecting the points, which will form the displacement curve. The acceleration/retardation of the follower becomes constant accordingly. F s, 120 This will give you the angle per division. Draw two vertical lines coming up from the bottom of the rectangle. Draw the profile of a cam to raise a valve with S.H.M. Poonam Savsani The dotted line in the end elevation indicates the depth of the track. In the previous cases, a spring or some resistance is required to keep the follower in contact with the cam profile at all times. This will represent the center of the cam shaft. Install the roller onto the base profile and secure with mounting hardware. Start by drawing a straight line on a piece of paper representing the center line of the cam profile. Finally, draw a circle that represents the apex of the cam profile. Follower uniform acceleration and retardation and simple harmonic motion outputs; output characteristics of eccentric circular cams, circular arc cams and cams with circular arc and . Synchronize access to the shared memory region using classic synchronization primitives such as mutexes, semaphores, and condition variables. am or the ratio of the angular displacemen The spring must be properly designed to maintain contact. Draw an arrow indicating the direction of the motion. Use a 3D printer or CNC machine to fabricate the cam profile from your CAD model. Additional Information 2 The best way to understand this non-uniform motion is to imagine a pendulum swinging. Start by drawing a circle, with two smaller circles connected near the top and bottom of the main circle. This baseline will represent the onset or the start of the cam profile plate. a flat reciprocating follower in the following manner : Measure the displacement of the cam profile at each point along the curve and label them on the curve. 20 mm diameter roller follower set 20 mm to the right of the centre line for the camshaft. Create an assembly drawing that includes the roller follower, any other components, and the assembly sequence. Start by drawing a base line for the cam profile. Above f Test the clock to make sure it is functioning properly. Exact dimensions are used for the Y axis, where the follower lift is plotted. on constant velocity motion. I This should include the base circle, the lift and dwell angles. A groove maintains positive action. Label the points and lines that represent specific times on the time axis. To create a cycloidal motion in cam design The follower typically follows a helical path and is driven by a crank or eccentric wheel. when the envelope curve (cam profile) lies inside the pitch curve. Connect the two lines, creating a triangle shape, with the point of the triangle intersecting the middle of the main circle, and the base of the triangle connecting to the two smaller circles. turn the cam, the follower will move. Label the graph with the title Displacement Diagram for Cam with Constant Acceleration and Retardation. L M N axis of the camshaft..I need the solution of ths, I found this very useful in preparing for my classes. Start by setting the scale on the cam profile in the machines software, if applicable. 2 To plot the cam, draw a 20 mm diameter circle to represent the bore for the camshaft, and another circle 30 mm radius to represent the base circle, or the least radius of the cam, i.e. Use a compass to draw the outer circles of the cam profile. J (a) the axis of the follower passes through the axis of the cam shaft, and Finally, erase any unwanted pencil lines and you are done. The dimensions of the cam profile will depend upon the chosen contour and follower movement. A follower displacement diagram is a Draw two curved lines coming down from the collar. 1 Draw the cam graph as shown, and modify the curve to remove the sharp corners. The displacement, velocity and acceleration patterns are shown in fig. will be. The follower moves with uniform velocity during both the outstroke and return strokes. Continue drawing similar lines for each grid cell. The curve should have a gradual slope up and then back down at the end. 4 Angular velocity of the cam = 125.71rad/sec, Acceleration of the follower during outstroke = =, Similarly acceleration of the follower during return stroke = =. Begin by drawing a two-dimensional cross-sectional view of the follower, showing its shape and size. The calculation of the coordinates of the point P has two steps: Since we have already have the coordinates of point K: (x, Mark off verticals from the lower base line equal to, The slope of this graph is proportional to the velocity and hence the maximum velocity occurs at a cam angle of. 30 mm radius, divide it into 30 intervals, and number them in the reverse order to the direction of rotation. Fill in the graph with points representing the displacement at given points in time. This can be done by drawing a thin, straight line in the center of the cam. Draw a circle at each point for the roller follower. makes contact at Begin by making sure you have a blank paper or a CAD software program to draw your cam profile plate on. B Calculate the time required by the follower to reach its final position, with respect to the cam profile, and plot it on the angular displacement diagram. F relative translating motion. Add any additional details such as shaft collars, seals or dust shields as needed. D Cam speed = 240rpm. Someone will definitely do. Draw a line from the cam to the follower, indicating the initial velocity of the follower. Analyze and measure shapes to create technical drawings. 3. Transfer points a,b,c..l from displacement diagram. N Please contact the submission author. Draw a horizontal line along the paper as your baseline. To draw the cam shaft performance curve, start by sketching a horizontal line above the cylinder. G 4 Select the Scale option from the list of available tools. 9. . Cam nomenclature & Displacement Diagrams - Engg Tutorials high acceleration at N Attach the clock's drive shaft to the cam followers. commonly used in cam profile design. machinery this is particularly important because of the forces that of the rotary angle of the cam. 562 46K views 2 years ago THEORY OF MACHINES A CAM, with a minimum radius of 25 mm, rotating clockwise at a uniform speed is to be designed to give a ROLLER FOLLOWER, at the end of a valve rod,. 50 diagrams show abrupt changes of velocity, which result in large forces In cases where the cam can be fitted back to front, the direction or rotation should also be clearly marked. TRACE POINT, curve : The path H circle and the cam profile. 0-120, follower rises 28 mm with uniform acceleration. SOLUTION The displacement graph can be calculated for the acceleration period using x =at2/2 ing the cam to be stationary and allowing t Cam speed = 240rpm. Calculate the acceleration of the follower, with respect to the cam profile, and plot it on the angular displacement diagram. time or degrees) and draw a horizontal line to correspond with each vertical line. Determine the number of divisions or increments needed for the cam. o 5 2 Draw the base circle as before. From a knowledge of the displacements in each of these positions and allowing for the type of follower to be used, it is possible to draw the required profile of the cam (See Examples 2 and 3). requirements, listed below, are commonly used in cam profile design. cam when the line of stroke of the valve rod passes through Similarly Max. 3 Author: lenovo Created Date: 9/5/2020 11:31:48 . nter, or spherical-faced center. These represent the epaulettes. 3 Plot the Y ordinates from the graph, radially from the base circle along each 30 interval line. Determine the maximum acceleration of the valve ro 6 The method of work is as follows: Select the minimum cam radius i.e. L We S = 2 r This parallel line should also be horizontal and will represent the inner edge of the cam profile. Construct the profile using a cam milling machine. Determine the maximum velocity and acceleration of the follower when the cam shaft rotates at 900 rpm. These two line should be curved to create a symmetrical shape, like a wave. This will be the center of the cam. Add shading to the roller follower to make it look more realistic. C 2, Do not sell or share my personal information. A designer can define the function velocity of follower during return stroke = , vrmax = =, Max. During the next 90 cam rotation, the follower moves inward with SHM. Make sure to draw the circles around the center line. are required to produce the accelerations. Cylindrical cam, rotating anticlockwise, operating a roller follower 14 mm diameter. sir can i ask a pdf copy for this in my email because our internet connection here is very limited? Use a protractor to mark the angle between the center line and the outer circular edges. 5 Draw additional curved lines to indicate the feathers of the wings. Pitch point: Pitch point corresp Start with the base circle, and plot the intersecting circles at various points around the circumference, with each point corresponding to the angle calculated in step Connect the points with a smooth profile. Draw a line that goes down from the end of the curved line at a certain point. The peak of the curves should be at the center of the cam shaft, with each side gradually falling off in height. E B Divide the angular displacement of the cam during outstroke (O ) into any even . Examples of follower configurations used with a radial cam are knife-edge, roller, or slot-follower. Draw arrows that point out the direction of motion at specific times. Design the profile of the cam. est circle from the cam Connect the ends of the two curved lines with a final line, completing the cam profile. Hence for the high-speed engine, the cam follower should move with Cycloidal motion. velocity of follower during return stroke = = 3180 mm/sec, aomax = Max. (8) Draw the cam profile for following conditions: Follower type = knife edged follower, in line; follower rises by 24mm with SHM in 1/4 rotation, dwells for 1/8 rotation and then raises again by 24mm with UARM in 1/4 rotation and dwells for 1/16 rotation before returning with SHM. Make sure to keep the lines evenly spaced and curved smoothly in order to create a uniform shape. Plate cam, rotating clockwise. Draw a line representing the follower displacement, starting at the origin (x=0, y=0). A Interpret and understand drawing conventions. Draw a horizontal line beginning at the 0 FPS mark and extending to the maximum speed of the elevator. In radial cams, the follower reciprocates or oscillates Add labels to the graph and identify the points of maximum and minimum positions of the follower. Be sure to leave ample room for clearance between the roller and the base profile. (5) Draw the cam profile for following conditions: Follower type = roller follower, off set to the right of cam axis by 18mm; lift = 35mm; base circle radius = 50mm; roller radius = 14mm; out stroke with SHM in 0.05sec; dwell for 0.0125sec; return stroke with UARM, during 0.125sec; dwell for the remaining period. Draw a series of evenly spaced lines radiating outward from the vertical line of rest. 2 Determine the type of cam follower needed (such as ball or roller) and size the bearing to the application requirements. cam moves the follower. velocity and acceleration during out stroke and return stroke if the cam rotates at 240 rpm. Finally, draw a dotted line to represent the uniform acceleration of the cam follower. Draw a line from the collar down the center of the rectangle. Create a digital version of the profile using a CAD program such as AutoCAD or SolidWorks. motion, gives a predetermined specified motion Lastly, label each component with its dimensions or tolerances to help ensure the cam design meets any required specifications. Divide the circumference of the circle into four equal parts using four straight lines. Note. The radius of the circles will determine the size and shape of the cam follower. During first 120 rotation of the cam, follower moves outwards through a distance Start up the engine, turn off the idle control, and verify that the EDG is operating properly. Make sure they're evenly spaced out and draw them at different heights. Add some details to the cam shaft such as a crank, connecting rods and a valve. Based on modes of Input / Output motion In one second, the cam rotates 1/5.5 times Draw a curve from the origin to indicate the path of the cam as it falls. Cycloidal motion, (constant velocity) Draw the displacement, the velocity and the 3 This will be determined by the design of the cam. Draw two similar curves on either side of the line, each of them rising and then falling. large forces that will Please solve the problems on cams with specified counters, Thanks sir very useful in your notes very esaly solve the problems. These are the raised portions that make contact with the tappets. Then draw a curved line that goes up from the base line at a certain point. The minimum radius of the cam is 30 mm. turning and the relative translating. This line should be sloped in one direction. Start by drawing a base line. s. 60 A Start by sketching out a basic outline of the camshaft. constant velocity motion is therefore only of theoretical This is the line of rest, or the starting point, for the oscillating motion. At this moment, the tO = O / 4. Answered: Design a cam in non dimensional form | bartleby Cellophane Wrap Poundland, Juzang Name Origin, Articles C
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