Drawing velocity polygon for a press mechanism

In summary, the problem is that the velocity vector of joint B should be represented as perpendicular to the radius of that gear and pointing to the right.
  • #1
Archives_3
4
1
Homework Statement
Draw a velocity polygon and identify absolute and relative velocity
Relevant Equations
Velocity polygon
IMG-20230509-WA0002.jpg
Hello, I'm new to the forum, I want to ask help on this problem here, above is a press mechanism and I'm tasked to draw a velocity polygon based on this mechanism. The point of contact between the two gears is A and consider it as a swivel hinge (rotating but stay still), so I guess it's O2?

Here's my attempt

IMG-20230509-WA0003.jpg

But I feel like it doesn't quite right, if you can help me solve this problem I would be very grateful thank you.
 
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  • #2
Welcome, @Archives_3 !

Sorry, I don't see points A or O2 in your diagram.
 
  • #3
Lnewqban said:
Welcome, @Archives_3 !

Sorry, I don't see points A or O2 in your diagram.
My mistake sorry, A is the point of contact between two gears. Now because the instructions that I've not put it in here says that considers A as a swivel hinge, then I assume then A becomes O2.
WhatsApp Image 2023-05-09 at 10.16.35.jpeg

Here's the picture again, I edited the A and B so to not cause confusion anymore I hope.
 
  • #4
Thank you.
If those discontinuous lines are the meshing circles of two gears with fixed centers, I don't understand the swivel idea.
The bigger gear should have a clockwise rotation.
In that case, the velocity vector of joint B should be represented as perpendicular to the radius of that gear and pointing to the right.
That vector then determines the velocity vectors of joints C, D and E.
 
  • #5
Lnewqban said:
Thank you.
If those discontinuous lines are the meshing circles of two gears with fixed centers, I don't understand the swivel idea.
The bigger gear should have a clockwise rotation.
In that case, the velocity vector of joint B should be represented as perpendicular to the radius of that gear and pointing to the right.
That vector then determines the velocity vectors of joints C, D and E.
WhatsApp Image 2023-05-09 at 10.57.00.jpeg

So can I see the problem like this?
 
  • #6
Yes, but only if I am correct about the gears and other assumptions.
Could you consult with your professor?
Is it a number-less assignment, just to represent those vectors in a rough way?
 
  • #7
Oh okay I understand, I will consult it when I have a chance,
Yes it's a number-less assignment
Thank you for your help
 
  • Like
Likes Lnewqban

1. What is a velocity polygon for a press mechanism?

A velocity polygon for a press mechanism is a graphical representation of the velocities and accelerations of the various parts of a press machine. It helps to visualize the motion and forces involved in the press mechanism.

2. How is a velocity polygon created?

A velocity polygon is created by first identifying the various parts of the press mechanism and determining their velocities and accelerations. These values are then plotted on a graph, with the velocities on the horizontal axis and the accelerations on the vertical axis. Lines are then drawn connecting the points to create the velocity polygon.

3. What information can be obtained from a velocity polygon?

A velocity polygon provides information about the relative velocities and accelerations of the different parts of a press mechanism. It can also show the direction and magnitude of forces acting on the different parts, which can be useful in analyzing the performance and efficiency of the press mechanism.

4. Why is a velocity polygon important in press mechanism design?

A velocity polygon is important in press mechanism design because it allows engineers to visualize and analyze the motion and forces involved in the press mechanism. This can help in identifying potential design flaws and optimizing the performance of the press machine.

5. Are there any limitations to using a velocity polygon for press mechanism design?

While a velocity polygon can provide valuable information, it is limited to representing only the velocities and accelerations of the various parts of a press mechanism. It does not take into account other factors such as friction, material properties, and external forces, which may also affect the performance of the press machine.

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