Kinematics of Machines

Introduction of Kinematics of Machines

1. KINEMATICS OF MACHINES UNIT-1 BASIC MECHANISM

2. THEORY OF MACHINES KINEMATICS OF MACHINERY DYNAMICS OF MACHINERY STATICS KINETICS

3. Kinematics Kinematics is the branch of classical mechanics which describes the motion of points, bodies (objects) and systems of bodies (groups of objects) without consideration of the causes of motion.

4. MACHINE

5. RESISTANT BODY

6. LINK or ELEMENT

7. EXAMPLES FOR LINK

8. TYPES OF LINK

9. RIGID LINK

10. FLEXIBLE LINK

11. FLUID LINK

12. STRUCTURE

13. MACHINE Vs STRUCTURE

14. KINEMATIC PAIR

15. CLASSIFICATION OF KINEMATIC PAIRS Based on type of Contact Based on type of Relative motion Based on type of constraint

16. 1. Based on Nature of contact or Type of contact

17. 2. Based on Nature of relative motion between them or Type of relative motion

18. 3. Based on Type of constraint

19. BASED ON NATURE OF CONTACT IN KINEMATIC PAIRS LOWER PAIR HIGHER PAIR

20. LOWER PAIR

21. HIGHER PAIR

22. DEPEND ON RELATIVE MOTION IN KINEMATIC PAIRS

23. ii) Turning pair

24. iii) Rolling pair

25. iv) Screw pair (helical pair)

26. v) Spherical pair

27. DEPEND ON CONSTRAINING MOTIONS IN KINEMATIC PAIR

28. TYPES OF CONSTRAINED MOTIONS

29. 1. COMPLETELY CONSTRAINED MOTION

30. 2.INCOMPLETELY CONSTRAINED MOTION

31. 3.SUCCESSFULLY CONSTRAINED MOTION

32. KINEMATIC CHAIN

33. HOW TO FIND KINEMATIC CHAIN OR NOT

34. EXAMPLE .1 ARRANGEMENT OF THREE LINKS

35. SOLUTION

36. EXAMPLE-2 ARRANGEMENT OF FOUR LINKS

37. EXAMPLE – 3 ARRANGEMENT OF FIVE LINKS

38. JOINTS

39. 1.Binary joint Here, Number of Links = 4 Number of Binary Joints = 4 If two links are connected at the same joint, it is called a Binary Joint

40. Checking whether it’s a kinematic chain

41. 2.Ternary joint If three links are connected at the same joint, it is called a ternary joint. For the given Diagram, Apply Kline’s Criterion, Number of Joints , j = Number of binary joints + 2 ( Number of Ternary Joints ) = 3 + ( 2 x 2) = 7

42. 3.Quaternary Joint Number of Joints , j = Number of binary joints + 2 ( Number of Ternary joints) + 3 ( Quaternary Joints)

43. DEGREES OF FREEDOM (DOF): It is the number of independent coordinates required to describe the position of a body.

44. DEGREE OF FREEDOM OR MOBILITY Degree of Freedom for plane Mechanism m (mobility): It is defined as the no of input motions, which must be independently controlled in order to bring mechanism into useful engineering purpose.

45. (a) Siding pair [DOF = 1] (b) Turning pair (revolute pair) [DOF = 1]

46. (c) Cylindrical pair [DOF = 2] (d) Rolling pair [DOF = 1]

47. . (e) Spherical pair [DOF = 3] Eg. Ball and socket joint (f) Helical pair or screw pair [DOF = 1]

48. PROBLEMS

49. FIND THE DEGREE OF FREEDOM(MOBILITY) FOR THE GIVEN DIAGRAMS

50. EXAMPLE-1

51. EXAMPLE-2

52. EXAMPLE - 3

53. EXAMPLE-4

54. EXAMPLE -5

55. INVERSION MECHANISM Inversion of a kinematic linkage or mechanism is observing the motion of the members of the mechanism with fixing different links as reference frame. Each time when a different link is chose as the frame link the mechanism shows different characteristics of the motion. KEEPING ANY ONE OF THE LINK FIXED AND ROTATING OR OSCILLATING OTHER LINKS- THIS RESULTS DIFFERENT FORM OF MOTION OUTPUT FOR DIFFERENT USAGE

56. Inversion of Mechanisms

57. Types of kinematic chain

58. . How to use Drag the red point. The red point moves on a line when "Line" option is selected. The red point moves on a circle when "Circle" option is selected.

59. examples

60. Inversions of Grashof’s chain

61. Inversions of Grashof’s chain

62. Inversions of Grashof’s chain

63. INVERSIONS OF FOUR BAR CHAIN

64. INVERSIONS OF FOUR BAR CHAIN

65. INVERSIONS OF FOUR BAR CHAIN

66. INVERSIONS OF FOUR BAR CHAIN

67. INVERSIONS OF FOUR BAR CHAIN

68. FIRST INVERSION -

69. SECOND INVERSION

70. COUPLING ROD OF A LOCOMOTIVE – USED TO TRANSMIT ROTATION FROM ONE WHEEL TO ANOTHER WHEEL EXAMPLE --- IN TRAIN .

71. THIRD INVERSION

72. WATT INDICATOR MECHANISM- USED TO SHOW THE STEAM PRESSURE IN THE CYLINDER

73. PANTOGRAPH - USED TO ENLARGE THE SMALL GIVEN DIAGRAM

74. WORKING --- PANTOGRAPH

75. "Pantograph" is a drawing instrument to magnify figures. Tracing the original figure by moving the red point, we can automatically obtain the magnified figure with the pen at the blue point . Find the ratio of magnification when the lengths of the arms are defined in the right figure.

76. ACKERMAN STEERING

77. INVERSIONS OF SINGLE SLIDER CRANK CHAIN

78. First Inversion

79. Second Inversion

80. .

81. .

82. Third Inversion

83. .

84. .

85. Crank and slotted lever quick return motion mechanism

86. Application of Crank and slotted lever quick return motion mechanism

87. Fourth Inversion

88. Pendulam pump or Bull Engine

89. Hand Pump

90. INVERSIONS OF DOUBLE SLIDER CRANK CHAIN

91. ,

92. Second Inversion

93. Third Inversion

94. .

95. .

96. Toggle mechanism, UNIT - I

97. Toggle mechanism

98. toggle mechanisms The toggle mechanisms can be used in the situation when one needs to output large force subject to a short stroke, for example, the stone crushers and mechanical presses, etc. The shown mechanism has a toggle position when the two lower links arrange to be aligned. At this position, the slider can produce an extremely large power to press workpiece.

99. . .

100. Intermittent motion mechanisms Ratchet and pawl mechanism

101. Application of Ratchet Pawl mechanism

102. , .

103. . .

104. Intermittent motion mechanisms Geneva wheel mechanism

105. Snap Action Mechanism . Its known as toggle mechanism or flip flop mechanisms

106. Hooke’s joint

107. Straight line generators Unit -1

108. Scott Russell straight line Mechanism

109. Arrangement The green link is 2 times greater than the length of blue link. This blue link is pinned as shown in fig with green link. One more requirement is that the slider's connection pin needs to be sliding in a line that would intersect the static pivot end of the short link.

110. Scott Russell straight line Mechanism The complexity of the mechanisms to generate exact straight lines can be reduced by introduction of one or more slider crank linkages. It is possible to generate an exact straight line using the slider crank mechanism but the range of motion is limited. Based on the geometry of the linkage the output motion is a simple sine function of the drive link or a simple harmonic motion. It is evident from the figure that this mechanism is made up of isosceles triangles, AB, AC and AO2 are of equal lengths.

111. Peaucellier Exact Straight Line Mechanism Peaucellier linkage can convert an input circular motion to the exact straight line motion. The construction of this mechanism is such that the point which is connected to the crank moves in a circular path and the point traversing the straight line is selected as the output point. The linkage has a rhombic loop formed of the equal length members, 5, 6, 7 and 8. Two equal length links are connected to the opposite corners of the rhombus at one end and to a common fixed point O 4 at the other ends. The point A of the rhombus is connect to fixed point O2 through the link 2. The length of the link 2 is equal to the distance between points O2 and O4. By the constraints of the geometry point A moves in a circular path and as the point A moves in a circle point P traverses an exact straight line path normal to the line joining O2 and O4.

112. Peaucellier Apparatus --- For drawing straight lines

113. MECHANICAL ADVANTAGE OF MECHANISM -------- a quality measure Due to more usage of 4 bar mechanism, its necessary to study some of the advantages of mechanisms. Which tell whether the mechanism is good one or not. It’s a quality measure of all mechanism

114. MECHANICAL ADVANTAGE It’s the ratio of output torque to the input torque M.A (ideal) = M.A (Actual) = T A = Driving link torque T B = Driven link Torque

115. Transmission Angle The angle between Coupler and the follower

116. Effect of Transmission angle on mechanical advantage .