help to set two gears in motion

Discussion in 'Pro/Engineer & Creo Elements/Pro' started by Ulises Diego, Nov 12, 2003.

  1. Ulises Diego

    Ulises Diego Guest

    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 Diego, Nov 12, 2003
    #1
  2. Ulises Diego

    David Janes Guest

    : 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 Janes, Nov 14, 2003
    #2
  3. Ulises Diego

    Ulises Diego Guest

    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?
     
    Ulises Diego, Nov 17, 2003
    #3
  4. Ulises Diego

    David Janes Guest

    : 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
     
    David Janes, Nov 17, 2003
    #4
  5. Ulises Diego

    Ulises Diego Guest

    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
     
    Ulises Diego, Nov 22, 2003
    #5
  6. Hi there, could you please explain me how to set a gear freely in
    motion with pin locator. Thanks in advance
     
    Shankar Venkateswaran, Nov 23, 2003
    #6
  7. Ulises Diego

    David Janes Guest

    : 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
     
    David Janes, Nov 24, 2003
    #7
  8. Ulises Diego

    David Janes Guest

    : 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
     
    David Janes, Nov 24, 2003
    #8
  9. Ulises Diego

    Pete Guest

    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
     
    Pete, Nov 24, 2003
    #9
  10. Ulises Diego

    David Janes Guest

    : 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
     
    David Janes, Nov 24, 2003
    #10
  11. Ulises Diego

    Pete Guest

    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
     
    Pete, Nov 25, 2003
    #11
  12. Ulises Diego

    David Janes Guest

    : 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
     
    David Janes, Nov 25, 2003
    #12
  13. Ulises Diego

    Pete Guest

    Did you receive the mpeg file?
     
    Pete, Nov 25, 2003
    #13
  14. Ulises Diego

    David Janes Guest

    : 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
     
    David Janes, Nov 25, 2003
    #14
  15. Ulises Diego

    Pete Guest

    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
     
    Pete, Nov 25, 2003
    #15
  16. Ulises Diego

    David Janes Guest

    <snip>
    : Doesn't account for thinning, though.
    :
    Just throw some lapping compound on them. They'll wear in in a couple days.
     
    David Janes, Nov 25, 2003
    #16
  17. Ulises Diego

    Doug Guest

    Doug, Nov 26, 2003
    #17
  18. Ulises Diego

    David Janes Guest

    : 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
     
    David Janes, Nov 26, 2003
    #18
  19. Ulises Diego

    Ulises Diego Guest

    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
     
    Ulises Diego, Dec 1, 2003
    #19
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