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Thread: mechanism

  1. #1
    Associate Engineer
    Join Date
    May 2020
    Posts
    1

    mechanism

    Can you explain me how does it work?

    Circular into rectilinear motion. The waved-wheel or cam on the upright shaft communicates a rectilinear motion to the upright bar through the oscillating rod.

    i've not understood
    Cattura.JPG

  2. #2
    Principle Engineer
    Join Date
    May 2015
    Posts
    198
    search: Tilt-a-Whirl

  3. #3
    Banned
    Join Date
    May 2020
    Posts
    5
    A slider-crank mechanism is a typical design which converts rotary motion into linear motion. It is achieved by connecting a slider and a crank with a rod.

  4. #4
    Associate Engineer
    Join Date
    Jan 2021
    Posts
    1
    Design Requirement

    (Refer to Table 1 for variables and values)


    1. A mechanism is to be driven by an electric motor turning at constant speed and direction. The speed of the motor must be a multiple of 10 rpm.
    2. Two motion outputs are required from the mechanism. The motions are all on a single plane. Their descriptions are as follows:
      1. A linear reciprocating motion of a slider along the horizontal axis with a stroke of S. The expected tolerance is 0.5 mm.
      2. A rocking motion with a throw angle of θ degrees. The expected tolerance is 1. One of the angular position limits of the rocker must be vertical.


    3. To reduce the forces in the joints,
    4. The coupler ratio of the sliding mechanism must be made greater than 4.
    5. The transmission angle of the rocking mechanism should be between 35 and 145.
    6. The space occupied by the moving parts of the mechanism should be minimized. The coupler ratio of the sliding mechanism should be less than 6.
    7. The time ratio of the sliding mechanism must be at least 1.07.
    8. The highest speed attained by the sliding mechanism must be between VMIN and VMAX mm/s.
    9. Each project group must use the assigned values S, θ , VMIN and VMAX as shown in TABLE 1




    TABLE 1:
    The dimensional and motion constraints of the mechanism for each group.





    Group Stroke
    S
    Throw Angle θ Maximum Slider Speed
    VMIN VMAX
    No mm degree mm/s mm/s
    1 170 75 800 1000
    2 190 85 900 1100
    3 210 95 1000 1200









    Design Tasks

    The output of the design project is in the form of a brief report (50%) and a presentation (50%).



    1. REPORT




    The report should have the following contents:



    1. Introduction


    A brief description of the mechanism, the aim of the project and the design requirement (~2 pages)



    1. Methodology


    The design approach. (~2 pages). Should show and justify how the design parameters were finalized.



    1. Results


    Sample design calculations (2-3 pages)

    Diagrams (To be plotted based on calculations performed using MS Excel, not ADAMS)


    1. The kinematic diagram of the mechanism showing the slider at mid-stroke position.
    2. The slider displacement curve for 2 cycles.
    3. The slider velocity curve for 2 cycles.
    4. The slider acceleration curve for 2 cycles.
    5. The rocker angular displacement curve for 2 cycles.
    6. The rocker angular velocity curve for 2 cycles.
    7. The rocker angular acceleration curve for 2 cycles.






    1. Conclusion


    Design Specifications


    1. The lengths of all links, the slider offset.
    2. The strokes of the slider and the rocker.
    3. The crankshaft speed in rpm
    4. The time ratios of the slider and the rockers.
    5. The coupler ratio of the slider.
    6. The range of transmission angles of the rocker.
    7. The working area required by the mechanism (in terms of L x W).
    8. The maximum speed of the slider and the rocker




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