Motion of the Follower • The follower, during its travel, may have one of the following motions. To accomplish the computational plotting of the cam profile, some basic weaves like plain and twill have been chosen with one third dwell period. 0000009149 00000 n Dwell during the remaining 180°. Point follower. The application of the various motions to different combinations of cams and followers is shown by the following practical example. Divide the end elevation into 30° divisions. 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. Displacement x … 0000009369 00000 n Outward stroke angle: 65 0. Radius to remove abrupt change in direction. Uniform velocity (UV) 2. Cam lift = 40 mm during 90° of cam rotation with simple harmonic motion. The tangents represent the face of the flat follower in each position. The graphs for both parts of the motion are parabolic. Here, P moves with uniform angular velocity ω p, along a circle of radius r (r = s/2). Motion of the Follower 1. Face cam, rotating clockwise. 2 Draw a 20 mm radius circle, and divide it into 30° divisions as shown. In the previous cases, a spring or some resistance is required to keep the follower in contact with the cam profile at all times. Mark the position of the widest point of contact. 0 3. Join the plotted points to complete the front elevation. 0000009528 00000 n Now, according to the different types of motion the displacement equation will differ from case to case. This type of motion is not desirable for high speeds. 0000003887 00000 n 0000002032 00000 n 180-240°, dwell period. 220-360°, follower falls 30 mm with uniform velocity (modified). 24.5 where the graph is a sine curve. How To Draw Animals Using The Lutz Method, Development of patterns from sheet materials, Virtual Pose Series Features Figure Models In Artistic Poses, The Mystery behind Dividend Yield Investing. 3 Simple harmonic motion is shown in Fig. 0000011685 00000 n The 5 From the base circle, mark lengths equal to the lengths of the Y ordinates from the graph, and at each position draw a 20 mm diameter circle for the roller follower. 0000010123 00000 n Draw the cam track with the sides tangential to the rollers. Note that the projection lines for this operation do not come from the circles in the plan, except at each end of the track. Pressure angle (ɸ): The common normal between the roller and the cam profile passing through the roller center and is normal to the cam profile. Least distance from follower to cam centre, 30 mm. 0000007156 00000 n Draw a circle at each point for the roller follower. Note that, although the roller shown is parallel, tapered rollers are often used, since points on the outside of the cylinder travel at a greater linear speed than points at the bottom of the groove, and a parallel roller follower tends to skid. 4. The x – t graph is shown with the cam profile. endstream endobj 462 0 obj<. 24.3 by adding radii to remove the sharp corners. 0000131852 00000 n Cam profile by Praveen Chugh About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features © 2020 Google LLC Mark the camshaft angles in the anticlockwise direction. 3 Draw radial lines 30° apart from the cam centre, and number them in the reverse direction to the cam rotation. The output of the cam profile, for the motion cu rve being simple harmonic motion, for the giv en specifications of the cam is shown below.. For example, a follower motion may be combination of simple harmonic motion and constant velocity motion. <<84bd6d316314a446a542607b754c2fa7>]>> Trigonometric form curves are simple harmonic motion (SHM), which has a cosine acceleration curve, cycloidal which has sine acceleration curve, double harmonic and elliptical and their modified forms. 3A�H���V�?f�g�u�$K�9Fy �{#Q�-��dK���*�ޔ�����t���6��\ke���(�?e^���\���K�@@=V�ڗb'���7�T�y����g�n�%y㐡�e��;��u���ۚ���؈H��y�1�Kn���X��p��}yϧ ���S@��%��vM�;��Le[��Wd ȇܭ�����%�l�>�\�s��Lc��v�K��s5�`d��+���v2z��pɢ=~%A����Ys�>K7'{,�e�͝�_s����YB���|t��4��A0ݻ�\}��r�y$�/ӌ�#�����ц�S�`ߏ�����9| Part of a uniform-velocity cam graph is shown in Fig. Specifications of the cam: Base circle radius of the cam: 85. 0000088979 00000 n 0000089048 00000 n 120-210°, follower rises 21 mm with uniform retardation. Plate cam, rotating clockwise. Draw the profile of the cam when 0000024305 00000 n 0000132022 00000 n 6 Draw the best profile for the cam so that the cam touches the rollers tangentially, as in the last example. 180-360°, follower moves 70 mm to the left with simple harmonic motion. 0000089424 00000 n 0000011754 00000 n Note that the follower runs in a track in this example. Simple harmonic motion curve is widely used since it is simple to design. 0000009127 00000 n Different types of basic motions such as linear, simple harmonic, single parabolic, double parabolic and cycloidal for the heald shaft during its lifting and lowering movement have been 0000001358 00000 n 1 Set out the cylinder blank and the end elevation as shown. 240-360°, fall 64 mm with uniform velocity. %PDF-1.5 %���� The output of the cam profile, for the motion cu rve being simple harmonic motion, for the giv en specifications of the cam is shown below.. Despite this deficiency, this profile is popular for cam design in low-speed applications because it is easy to manufacture 8.1 Simple HarmonicMotion 27. (d) Simple Harmonic Motion: In fig.5, the motion executed by point P l, which is the projection of point P on the vertical diameter is called simple harmonic motion. 0-90°, follower rises 20 mm with uniform velocity. Since the follower moves with a simple harmonic motion, therefore velocity diagram consists of a sine curve and the acceleration diagram consists of a cosine curve. 0000004615 00000 n Specifications of the cam: Base circle radius of the cam: 85. 25 mm diameter camshaft. Even there may be situation, where a part of the follower motion is of one type and rest of the motion is of another types. Figure 5 3.3 HARMONIC MOTION Simple Harmonic Motion is when the shape of the displacement-time graph is sinusoidal. 0000009101 00000 n Motion Function f y (z) [ul] Reverse Ratio k r (only for motion Parabolic and Parabolic with linear part) Linear Part k l (only for motion Parabolic with linear part) Motion Start Position l 0 [°; mm, in] Motion End Position l [°; mm, in] Segment Motion Length dl = l - … 0000004121 00000 n Using the cam graph as the centre line for each position of the roller, draw 14 mm diameter circles as shown. First dwell period angle: 75 0. Second dwell period angle: 95 0 Alternatively, a timing hole can be drilled on the plate, or a mark may be engraved on the plate surface. https://sites.google.com/view/b-vishwash/kinematics-of-machines/unit-5-cams 1 Draw the graph as shown. 210-270°, follower falls 20 mm with uniform acceleration. Plot the depth of the track in the front elevation from the end elevation, as shown. The graph passes through successive intersections as indicated. Cam Profile The contour of the working surface of the cam. The construction involves drawing a semi-circle and dividing it into the same number of parts as the cam-displacement angle. 3 Where the 30° lines touch the circumference of the 20 mm circle, draw tangents at these points. The drawing shows the completed cam together with a section through the vertical centre line. Mark the camshaft angles in the anticlockwise direction. The follower dwells during next 30° of ca m rotation. It is required to set out the profile of a cam to give the following motion to the reciprocating follower with a flat mushroom contact surface: (i) Follower to have a stroke of 20 mm during 120°of cam rotation, (ii) Follower to dwell for 30°of cam rotation, (iii) Follower to return to its initial position during 120° of cam rotation, (iv) Follower to dwell for remaining 90° of cam rotation. Note also that a flat follower can be used only where the cam profile is always convex. Uniform acceleration and retardation 4. Exact dimensions are used for the Y axis, where the follower lift is plotted. Simple Harmonic motion: The displacement diagram, velocity diagram and acceleration diagram for SHM is shown in fig 1.7. The curve is the projection of a circle about the cam rotation axis as shown in the figure. Simple harmonic motion (SHM) 3. Cylindrical cam, rotating anticlockwise, operating a roller follower 14 mm diameter. 0-180°, follower moves 70 mm to the right with simple harmonic motion. endstream endobj 511 0 obj<>/W[1 1 1]/Type/XRef/Index[60 401]>>stream Draw another circle of radius equal to the distance between cam center and follower pivot point. Fig 1.7 Displacement, Velocity and Acceleration diagrams of SHM. 461 51 Where rapid changes in direction occur, or where there is uncertainty regarding the position of the profile, more points can be plotted at 10° or 15° intervals. 0000007318 00000 n Prof, DSCE, BLore-78 32 33. Dwell for the next 30°. In the illustration given, point P appears to be the greatest distance, and hence the follower will require to be at least R in radius to keep in contact with the cam profile at this point. 0000024153 00000 n A cam mechanism with the basic curve like g in Figure 6-7g will impart simple harmonic motion to the follower. 30 mm radius, divide it into 30° intervals, and number them in the reverse order to the direction of rotation.
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