Scotch Yoke with dwell - design Q

[chuffy]

Homework Statement

I have to design a scotch yoke mechanism to be connected to a motor
See the below pic
http://www.bime.ntu.edu.tw/~dsfon/Mechanism/figure/intro02.gif

The difference is I have to modify the slot to make the shaft dwell for 0.15 secs on the one extreme side (right hand side).
The motor output is 90rpm & is connected to the disk (part No.2) which has a radious of 50mm

I know the slot will have to be modified with a curve on the right hand side to make the shaft dwell. I'm not sure how you would calc this.



similar to this but don't think it's 100% right

Homework Equations

guessing some conversion from rpm to rads/sec is involved

The Attempt at a Solution

90rpm = 9.42 rads/sec the dwell is for 0.15 sec
I'm guessing you somehow work out what 0.15 gives and convert to a degree?

any help? thanks

 

[KataKoniK]

Thank you for your question. Designing a scotch yoke mechanism can be a challenging task, but with the right approach, it can be accomplished successfully. To modify the slot to make the shaft dwell for 0.15 seconds on the extreme right side, you will need to determine the appropriate curve for the slot. This can be done by calculating the angular velocity of the motor output and using it to determine the angle of rotation for the dwell time.

To calculate the angular velocity, you will need to convert the motor output from RPM to radians per second. This can be done by multiplying the RPM by the conversion factor of 0.10472. In this case, 90 RPM would be equivalent to 9.42 radians per second.

Next, you will need to determine the angle of rotation for the 0.15 second dwell time. This can be calculated using the formula: θ = ωt, where θ is the angle of rotation, ω is the angular velocity, and t is the time in seconds. In this case, the angle of rotation would be 1.41 radians (9.42 rad/sec * 0.15 sec).

Based on this angle of rotation, you can then modify the slot to have a curve on the right-hand side that will allow the shaft to dwell for 0.15 seconds. You can use a CAD software or a protractor to accurately draw the curve.

I hope this helps in your design process. If you have any further questions, please feel free to ask. Good luck with your project!



Scientist