Pro Mechanica Motion

I've been trying to get this to work for days. Basically, I have a
piston (disc shape) and a cylinder (tube shaped). Both are just
1-feature parts- the piston is just a 10cm. diameter circle protruded
5cm., and the cylinder is just a sketch of 2 concentric circles to get
the hollow shape, with the inner cicle having a diameter of 10cm. and
the outer circle having a diameter of 12cm, protruded 30 cm.

All I want to do is show the piston move to the end and back of the
cylinder. I'm sure someone out there knows how to do it- I am using
Pro/E 2001. Would someone be so kind as to provide a step-by-step
guide of how to do it? Keep in mind that this is my first time trying
to do the "motion" thing- I am very good at regular Pro/E, but know
nothing about "motion".

Thanks in advance!

Jurgen

 

OK, first off, do you have Motion operational? You need a "C" compiler.
There also is a product called MDX which will give you kinematics but
not dynamic (force) information. If all you want to do is animate I
think you can do this through something called Mechanisms... or is this
MDX?

Has anyone else heard that official support for Motion goes away in
2004? MDO will be the replacement.

So what have you tried doing? Basically, any stationary pieces are
"ground" and don't really participate in the analysis. You need a
translating joint between ground and the piston and something to move it
back and forth. Usually this is demo'd with a slider crank where the
crank is spun. If you don't want to add those pieces and joints then
you'll need to write some sort of function to drive the piston back and
forth (a Driver in Motion terms)

-D

 

Jurgen, first check the following:
* Under Help, open Technical Support Info. Here you will find lots of
information about the installation, including installed modules, floating
licenses, date codes and builds. Under Configured Option Modules heading, check to
see if you have Mechanism_Design, Mechanism_Dynamics and/or Design_Animation (also
possibly Mechanica which you don't actually need for what you want to do, as the
first two options are 'junior' Mechanica Motion). If you do not have
Mechanism_Design, you'll have to try something more primitive, but it is still
possible to do.
* Assuming you have MDX, open your assembly of the cylinder and piston. With
the assembly of the piston and cylinder open, redefine the cylinder to get the
Component Placement interface. You should have placed the cylinder as the base
component using the Default placement. At the bottom of the window is an icon for
this. Redefine the component placement now if it wasn't placed this way. Also,
notice above the familiar constraints window a heading called Connections with an
arrowhead pointing right. Click on this arrowhead and the mechanism setup part of
assembly opens to show the implicit connection of your Default placement which is
a Rigid connection. This is the part which remains stationary. Part of what
confuses most people about Mechanisms is that you can't do the assembly and make
the connections in 'Applications>Mechanism' (or Mechanica, for that matter). You
need to do this with Connections from the Component Placement window.
* Now, redefine or place the piston in the assembly. If there are any hard
constraints which will prevent the piston form moving, i.e. any constraint which
would lock it in a fixed position along the length of the cylinder, remove the
constraint. Next, open the Connections setup window. Notice that it gives you a
default type of connection as Pin. Click on the Pin type to highlight it and open
the drop down list with the arrow. Each of these connection types has different
motion attributes (DOF, degrees of freedom; for a description of each what to use
them for, check the Help files under 'connections'.) In the case of the piston,
you should probably use 'Slider' as the connection type. It provides an axial
connection between cylinder and piston and a rotational constraint (plane to
plane).
* When the connection definition is complete, a message the bottom so
indicates. Click OK to close the Component Placement dialogue. You are not ready
to start Mechanism from the Applications menu. What remains to be done from this
menu is to give a connection or connections drivers, define the motion this driver
will create, including such things as speed or limits of motion, then run an
analysis which simulates the parts being driven by your 'motor'. When the analysis
has been run with no 'crashes' and performs to your satisfaction, you can do a
playback of the analysis, save it to disk with the drivers and motion definition
and capture the cycle as an mpeg. There is a PTC course available on MDX and it's
pretty comprehensive and detailed, much more so than this simplified introduction
can convey.

David Janes

: I've been trying to get this to work for days. Basically, I have a
: piston (disc shape) and a cylinder (tube shaped). Both are just
: 1-feature parts- the piston is just a 10cm. diameter circle protruded
: 5cm., and the cylinder is just a sketch of 2 concentric circles to get
: the hollow shape, with the inner cicle having a diameter of 10cm. and
: the outer circle having a diameter of 12cm, protruded 30 cm.
:
: All I want to do is show the piston move to the end and back of the
: cylinder. I'm sure someone out there knows how to do it- I am using
: Pro/E 2001. Would someone be so kind as to provide a step-by-step
: guide of how to do it? Keep in mind that this is my first time trying
: to do the "motion" thing- I am very good at regular Pro/E, but know
: nothing about "motion".
:
: Thanks in advance!
:
: Jurgen

 

David,

I was able to follow what you wrote. I do have the "Mechanism Design"
module. I was able to constrain my piston/cylinder by using an align
constraint (aligning the axis of the piston with that of the
cylinder), then I used the slider constraint, and I go the message
saying that the connection definition is complete.

From there, how do I get it to move? How do I give it the drivers,
and finally how do I "play" the motion?

Thanks

Jurgen

 

<snip>
: From there, how do I get it to move? How do I give it the drivers,
: and finally how do I "play" the motion?
:
: Thanks
:
: Jurgen
:
<snip>
This is what I wrote in my first reply. Try this at least and let us know how far
you get. Will help if you get stuck.
DJ

: > * When the connection definition is complete, a message at the bottom so
: > indicates. Click OK to close the Component Placement dialogue. You are now
ready
: > to start Mechanism from the Applications menu. What remains to be done from
this
: > menu is to give a connection or connections drivers, define the motion this
driver
: > will create, including such things as speed or limits of motion, then run an
: > analysis which simulates the parts being driven by your 'motor'. When the
analysis
: > has been run with no 'crashes' and performs to your satisfaction, you can do a
: > playback of the analysis, save it to disk with the drivers and motion
definition
: > and capture the cycle as an mpeg. There is a PTC course available on MDX and
it's
: > pretty comprehensive and detailed, much more so than this simplified
introduction
: > can convey. But you can also check the Help files on Drivers (Motors?), etc.
: >
: > David Janes
: >

 

When you make your barrel part, create a point at the end of your stoke on
the axis. This will be your reference point..
Create another point on the piston axis and face to be use as a follower
point.
Assemble the components using the "cylinder" option and the axis as
references.

Select Mechanism>Model>servo motors>new
Select Point as your driven entity.
Choose the point on the rod as your driven entity.
Chose the reference point on the barrel.
Choose the motion direction on the axis (flip if required)
Select Profile and set up your motion using Cosine.
Using a 12 inch stroke:
A=6
B=180
C=6
T=10
For other strokes A and C = Stroke/2
Next choose Analysis
New>motors
Select "Run"
All should work if you have done it right.
You can then save this analysis and playback the result.

Hope this works.
Doug