This tutorial shows how to assemble gears (that are imported) in SpaceClaim. The type of gears considered is “Internal Gears”. These are typically used in planetary gears. This is in continuation of our earlier tutorial on assembling external gears in SpaceClaim. Please go through it to catch up in this tutorial.
Here, we have to find the pitch radii of the internal gear (larger number of teeth) and the external gear (lesser number of teeth). Then, Gear Condition needs to be defined between these pitch cylinders for perfect mating of the gears at hand. The following diagram shows the equations of determining the radii R1 and R2 of the two cylinders, given the number of teeth in the gears and the distance between the centers of the gears. We have two equations with R1 and R2 and solving for R1 and R2 is straight forward.
In the video tutorial below:
- We have imported a Gear Assembly from GrabCAD.
- Make the internal gear as fixed component and define Tangent condition between the mating planes of the gears.
- The pitch cylinders are determined in the form of surfaces (which do not add up to the mass of the components).
- Gear condition is defined between them.
- Edit the property of Gear condition “Reverse Rotation Direction” so that the sense of rotation for external gears and internal gears are same (as opposed to that between two external gears, where the sense of rotation is reversed).
- Try to move the external gear. It does not move as required. This is because, the gear condition only makes sure that the relative rotation of the gears are as per the ratio of number of teeth [This is as of SpaceClaim 2012 version].
- Define a Tangent condition between the same set of pitch cylinders. Move the external gear and it follows the desired path. This needs to be defined so that external gear and internal gear mesh perfectly.
- Go to SC-Motion. Since we do not have a revolute joint to define rotation, we have defined Gravity for the assembly and let the external gear move due to the action of gravity (Dynamic Simulation)
The SpaceClaim assembly file (with Gear condition defined) can be downloaded here.