Join John Helfen for an in-depth discussion in this video Motion constraint, part of Autodesk Inventor 2018 Essential Training.
- [Voiceover] In this movie, we're going to look at how we can create rotary-to-rotary motion and rotary-to-linear motion. On the screen you can see Gears - Complete.iam and this is a model I created so you can see the final results of what we're about to create. If we expand Gear 1 in the browser, I have an Angle Constraint that you can right click on and select Drive to see this motion. I'm going to drive from zero to 1080, and I'm going to click the double arrows to expand the additional information.
And you can see that we're going to drive this in one degree increments, and that's what we want. I'm going to simply hit Play so that you can see the motion. Here we have the center gear rotating, and the outer gears rotating in the opposite direction causing this motion of the stage to ride down the shaft. If you right click on Angle 2 and select Drive, you can see that we get our drive dialogue, and right now we're going to drive from zero to 1080 degrees. If we click the double arrow, you can see that we're also going to drive at one degree increments.
I'm going to go ahead and collapse that and select Play. And you can see on the screen that we have rotary-to-rotary motion between the gears, and we have rotary-to-linear motion between the gear and the stage. If we reverse that, you can see that they move in both directions. And that's what we're going to create here with the Motion tab. To start, I have a file called Gears.iam where everything's in position and ready to go, but the constraints that cause the motion have not been created yet. We're going to begin by right clicking and selecting the Constraint option.
And this time we're going to go to the Motion tab in the dialogue box. And here you can see we have different types and selections and solutions, and the first one is Rotation and the second type is Rotation Translation. The first one will allow two gears to rotate and interconnect with each other, and the second one will cause a rotation in a gear to cause the stage to move. Let's go ahead and zoom in on the gears and have a look at how we can create some rotary motion. If I click the right view to look at this straight on, you can see that we have the three gears, and they're in a position where they're going to intermesh with each other.
In order to see this a little more clearly, let's go to the Navigation Bar and select the Shaded with Edges option. If you don't have this button, you can use the arrow at the bottom right, and select Visual Styles. This makes it a little bit easier to see the gears and how they're positioned. Here you can see they're not touching and they're in a position where they mesh with each other. So what we're going to do is rotate just a little bit so that we can see the face on the inside, and we're going to use this to select rotation around the center gear, and we'll select the face on the center of the outside gear, and left click to select it as well.
If you look closely, you'll see these arrows are both facing the same direction, and that's not what we want. When this rotates in one direction, we want the other to rotate in the opposite direction. So just like the Mate or Flush, there's multiple solutions here. We can have them moving in the same direction or forward, or we can have them in reverse, and that's what we want here. By selecting that, the arrows now are opposite of each other. If we go ahead and select OK, and apply that constraint and get out of the dialogue box, we can go back to Gear 1, and we can right click and select Drive on the Angle 2, and hit Play to see what the results are.
10 degrees isn't quite enough, so let's go ahead and bump this back up to 1080 and click Play again. Here you can see we are getting the motion we expected, and that's what we wanted, so we're going to go ahead and click Cancel, and then it will replace everything back to the position it was. Let's do that one more time on the opposite gear in order to create motion there. We'll right click in the Graphics Window, select Constraint, return to the Motion tab, and this time we're going to use the center face on the center gear, and we're going to select the center face on the right gear.
Now I'm going to hover over this and pause for a moment, and use the drop-down that Inventor presents to reach that face, the Access Vector face on the inside of that gear. And just like we did in the previous step, you can see by default, both arrows are facing in the same direction. So we're simply going to flip the solution, and select OK to create that constraint. Now if we right click on Angle 2 in the browser, and Drive it, you'll see that we have motion, both from the center gear to the right and the left gear.
Go ahead and click Cancel, and that'll return everything back to its original position. We're now ready to create the linear motion that'll cause this stage to slide down the shaft. We're going to go ahead and right click and select Constraint one more time. And this time when we get into the Motion Constraint, we're going to change the type of Motion Constraint. Rather than rotary-to-rotary, this time we're going to do rotary-to-translational. What we can do, is we can first select the rotary motion we want. We'll hover over that face again, and wait for the popup to appear, and here we can select Axis Vector 2.
And then we need to simply need to select a direction on this part for linear motion. To do that, let's go ahead and rotate a little bit. We could select a face, but in this case, we want this edge right here on the edge of the stage. And it doesn't matter where on the edge you pick, but you do need to pick the edge in the direction you want this to travel when the rotary motion happens. The other thing we want to do is set a distance. We need to set a distance this specific stage is going to travel. For every single revolution of the gear, how far do we want this to move? I'm going to go ahead and enter point five.
As the engineer, it's going to be up to you to determine the type of shaft you have and the distance that you're going to actually get from that shaft based on the threading you have. But for this demonstration, point five is plenty. I'm going to go ahead and select OK to create that constraint, and return to the Graphics window. And we're going to right click on Drive 2 in the browser one more time, and select Drive. This time when we hit Play, you can see that as the gears spin, the stage moves as well. If we rotate to the right, you can clearly see this.
If we play it in reverse, the opposite is true. So now you know how to create rotary-to-rotary motion and rotary-to-linear motion.
- Reviewing interface changes
- Projecting and importing geometry
- Working with Autodesk AnyCAD
- Understanding part modeling
- Building parts with placed features
- Working with partial chamfers