help to set two gears in motion

I am new in Pro-E, I try to set two gears in motion as a mechanism, I wonder
what should I do, any help?

 

: I am new in Pro-E, I try to set two gears in motion as a mechanism, I wonder
: what should I do, any help?
:
: --
: Ulises
:

I will assume that you know how to assemble and already have assembled the gears
so that each has a pin type connection and can freely turn. Next, go into
Mechanisms (Applications>Mechanism) and select the icon labelled 'Define gear-pair
connections' or from the Mechanism menu at the top, select Gears. On the gear
definition manager, press the 'New' button will open the 'Gear Pair Definition'
input screen where you can name the gear pair, select whether it will be standard
type driver/driven pair or rack and pinion, select the joint axis of whatever
gears will rotate and give it some numbers for pitch diameter and number of teeth
for each gear. The first gear you pick will be the 'carrier', the second will be
the 'gear'. When you selected and defined Gear1, click the Gear2 tab and define
the second gear. Pick a place to put the gear pair icon, click Okay and you're
done. Give one of them a motor, set up the Motion definition and you're off and
running.

BTW, this functionality started fairly recently, possibly even with Wildfire. I'm
not sure what you'll do if you have an older version of the software and there is
not gear pair connection available. You could possibly put a motor on each and use
both motors in your motion definiton, never tried it.

David Janes

 

David,

Thanks for the reply. very valuable information, unfortunately I haven't
been able to find the mechanism you have mentioned, I am afraid my version
of Pro-E doesn't have it, or has been restricted form the licence, I am
using Pro-E 2001 educational version.

I already have the gears spinning freely, but I haven't find the way to link
them at the diameter pitch, and putting a motor on each and use
both motors in motion definiton will be useful to show a motion, but I need
it to set an epicyclic gearbox to analyse the output speed in the arm and
the rig, so I am afraid I need to add a motor on only one gear and the other
should move as a consequence of the movement of the first one.

However, I appreciate your help, and in case you have any additional
comment, I will be really grateful

Ulises

PS. What version are you using at the moment?

 

: David,
:
: Thanks for the reply. very valuable information, unfortunately I haven't
: been able to find the mechanism you have mentioned, I am afraid my version
: of Pro-E doesn't have it, or has been restricted form the licence, I am
: using Pro-E 2001 educational version.
:
It's possible that 2001 doesn't have 'Mechanism>Gears', that this innovation
didn't come about until Wildfire. I'll check at school this evening where they
have license for 2001.

: I already have the gears spinning freely, but I haven't find the way to link
: them at the diameter pitch, and putting a motor on each and use
: both motors in motion definiton will be useful to show a motion, but I need
: it to set an epicyclic gearbox to analyse the output speed in the arm and
: the rig, so I am afraid I need to add a motor on only one gear and the other
: should move as a consequence of the movement of the first one.
:
I'm sorry I can't help you with this. I've seen quite a few gear boxes but never
one that could be described as epicyclic, even those with complicated planetary
gear systems. The motor control might be epicyclic, but not the gear box. Are you
talking about a motor control, a motion defintion?

David Janes

 

yes I was talking about motion definition (wonder if I am right) to set for
one of the gears. The epiciclyc geaxbox I am trying to model is actually a
complicated planetary gear system (wonder if it is because it is UK), that
needs two speed inputs to obtain one output (2 degree of freedom system ),
and that I agree is quite complex.

So, I will continue looking for a way to do it, and if I find anyway, I'll
let you know...

cheers

 

Hi there, could you please explain me how to set a gear freely in
motion with pin locator. Thanks in advance

 

: yes I was talking about motion definition (wonder if I am right) to set for
: one of the gears. The epiciclyc geaxbox I am trying to model is actually a
: complicated planetary gear system

One of the nice things about gears is that when a tooth moves in the driver,
another tooth moves exactly the same amount in the driven gear, one tooth in each.
The proportionality is decided by a simple ratio, even if it's something like 17
teeth in the driver to 79 teeth in the driven gear (17/79). One full turn of the
driver will produce a proportional motion in the driven governed by this ratio, or
17:79 in the driven.

This ratio then governs all the equations of motion used by Mechanism Design in
Pro/e. I'm not sure where, but there is a place in the epicyclic equation where
these values can be inserted for the driven gear to give you proportional motion.
So, in a time dependent system, the driver will be 17t/s. The driven will be
17:79t/s in a separate driver for the driven gear. In effect, they will appear to
move together, yet they will be separately driven, but in proportion to their
ratio. Both 'motors' will be used in the new analysis you run. If they both start
and stop at the same time, the driver will appear to be moving the driven gear.
Yes, it will be an illusion, but that's computers for you. And the result will be
the same. Loading, dampers and that kind of thing may not be possible when you
have not defined contact between teeth. The problem with defining this is that the
contact is intermittent. However, with starting conditions set properly, you
should be able to get the gears moving so that good involute tooth profile
produces no interference with interference checking set. With compound gearing and
idlers, you must do the gear pairs manually, based on the intial ratio.

David Janes

 

: Hi there, could you please explain me how to set a gear freely in
: motion with pin locator.

The problem everyone has is that they expect to be able to create mechisms with
'Applications>Mechanism'. No, the problem of making components in an asssembly
'moveable' was thought to be best approached in assembly. This is the function of
that little bar with the arrow above the usual constraints box called
'Connections'. If you click the arrow, you get a whole interface. In this
interface, you start with a base which is not moveable (for example, assembly
datums and axes for gear centers), then add components which are, in various ways,
with various DOF, moveable. Each connection type has different dofs. The pin type
connection allows complete freedom of movement around an axis but constraint in a
plane normal to the axis of movement. When each gear is thus contrained, it can
move freely about this axis. Then you go into 'Application>Mechanism'. At this
point, you have two gears, with packaged type constraints, i.e. moveable in at
least one DOF. The Mechanism menu gives you the ability to define 'motors' (a
movement defintion, such as a simple velocity or acceleration, continuing for a
certain duration.) At each increment of movement, a picture is taken, a snapshot,
which can be recorded with 'Capture' and turned into an MPEG file. The sequence of
movement may be run with interference detection so that any contact between bodies
will be recorded in red. A most wonderful tool!!

David Janes

 

A couple of years ago I modeled some gears and actually had them run
together with a 'cam' definition that allowed liftoff, by setting the
entire surface of each gear as the cam.

Very compute intensive, but it worked. Your gears need to be modelled
accurately, and the liftoff takes care of the relief at the bottom of
the tooth, as well as backlash.

Regards
Pete

 

: A couple of years ago I modeled some gears and actually had them run
: together with a 'cam' definition that allowed liftoff, by setting the
: entire surface of each gear as the cam.
:
If you define one gear as a cam, the other (driven, I suppose) has to be defined
as the cam follower? I don't get that. Have you seen this documented anywhere. I
sure would love to see it. What kind of gears? spur, helical, bevel, spiral bevel?
Helicals are somewhat more forgiving about liftoff because of tooth geometry. The
computing horsepower is coming along, so it might be time to try it again.

David Janes

 

Made this work last night in 2001. I modelled 2 spur gears, 20t, 20p.
Made 2 pins, assembled them at center distance (1.00), and pin
connnected the gears to them. Went into mechanism>model>cams and
defined the gear tooth surfaces of gear 1 as a cam 1, and the gear
tooth surfaces of gear 2 as cam 2, and enabled liftoff. Put a motor
on the joint axis of gear 1, and off they went.

Pete

 

: Made this work last night in 2001. I modelled 2 spur gears, 20t, 20p.
: Made 2 pins, assembled them at center distance (1.00), and pin
: connnected the gears to them. Went into mechanism>model>cams and
: defined the gear tooth surfaces of gear 1 as a cam 1, and the gear
: tooth surfaces of gear 2 as cam 2, and enabled liftoff. Put a motor
: on the joint axis of gear 1, and off they went.
:
Hey, that's great! Sure beats the way Wildfire is doing gear pairs where it
basically doesn't care whether gears mate, running the two at the pitch circle of
each, as if they were rubber rollers running against each other, and just using
the the ratio to determine the speed of the second gear. It's actually like the
SolidWorks method ~ smoke and mirrors, not real simulation but the illusion of
simulation.

Your way, aside from computing horsepower needed, at least offers the possibility,
with contact surfaces and real tooth geometry, of loading them, doing interference
studies, stress analysis and realistic speed, torque and other behavior curves at
the end of the drive train. Thanks and I hope Ulises Diego is getting this.

David Janes

 

Did you receive the mpeg file?

 

: Did you receive the mpeg file?

Yeah, thanks, very cool stuff. Are those gears the product of a gear design
program? I saw something for Pro/e from AGMA a few years ago and wish I'd kept it.

David Janes

 

Nah, made those myself a few years ago. Wish I'd known about the
templates and techniques available, because I used sketcher relations
to actually draw the involute, and then pattern it around; it's a real
beast. But very accurate, I've even double-checked my over pin dims
from my Excel program (that I also wrote) by sketching tangent circles
and measuring them. Doesn't account for thinning, though.

Regards

 

<snip>
: Doesn't account for thinning, though.
:
Just throw some lapping compound on them. They'll wear in in a couple days.

 

Try the gears designed on the following link.
http://www.geartechnology.com/mag/gt-model.htm

Doug

 

: Try the gears designed on the following link.
: http://www.geartechnology.com/mag/gt-model.htm
:
: Doug
:
Yes, thanks, Doug, those were the articles that I saw a few years ago. Somebody
had reprinted them, I thought, from a magazine, but possibly they were always
online. I remember the pictures were very bad, now removed. And I never could
figure out what the layout was that they referred to. Then there is the
unexplained Pro/PROGRAM input as a sidebar to the article. I guess I didn't get
very far with it at the time. Maybe I'll take another crack at it, useful at least
for explaining how to create an involute profile with the curve equation.

David Janes

 

Hi

I am now trying to model the gears following
http://www.geartechnology.com/mag/gt-model.htm to try the cam-follower, but
for some reason I can't see any picture, any of you happen to have the
pictures? to draw the gear in the easiest possible way

many thanks in advance

Ulises