Plastic Bevel Gear Design
Plastic Bevel Gear Design
(OP)
Hello all,
I am attempting to design a set of 2 plastic bevel gears to be injection molded. I have consulted the AGMA standards for bevel gearing and plastic gear design, but neither show how to design a gear tooth for a bevel gear. It seems to me that many bevel gears do not even have involute profiles. I have designed the main body of the gear fairly easily, and designing a basic rack is fairly straighforward, but does anyone know how to draw/design the gear teeth for a bevel gear?
Help is much appreciated.
I am attempting to design a set of 2 plastic bevel gears to be injection molded. I have consulted the AGMA standards for bevel gearing and plastic gear design, but neither show how to design a gear tooth for a bevel gear. It seems to me that many bevel gears do not even have involute profiles. I have designed the main body of the gear fairly easily, and designing a basic rack is fairly straighforward, but does anyone know how to draw/design the gear teeth for a bevel gear?
Help is much appreciated.





RE: Plastic Bevel Gear Design
RE: Plastic Bevel Gear Design
If it is the latter, then there are companies that specialize in plastic gear design. However, tooth deflection, stress distribution, and many other considerations are likely to need addressing and that's where experts come in.
Other than that they are involute, just not constant pitch across the face. I would expect that creating a curve at the smallest and largest part of the cone and linearly interpolating would be close. This may help:
www.atlantis-press.com/php/download_paper.php?id=2...
RE: Plastic Bevel Gear Design
Most of the straight bevel gears do not use the spherical involute shape at all, they use the octoid shape instead.
Here is some general info: http://www.gearsolutions.com/article/detail/6616/a...
RE: Plastic Bevel Gear Design
If true, what is the best way to go about designing the teeth with no standards?
RE: Plastic Bevel Gear Design
RE: Plastic Bevel Gear Design
Within each manufacturer; there are different machines that generate the profile in different ways.
So, as a gear designer, you need to be specific about which manufacture's profile you intend to use...............they are not interchangeable.
If producing the profile by molding; then you are free to use a theoretically correct profile..........with modifications for the molding process.
The main thing you'd need to consider is how the mold is going to be manufactured...........so speak to your manufacturer before embarking on your design.
Gear Geometry and Applied Theory, by Faydor L. Litvin, shows how to mathematically reproduce several of the more common bevel gear profiles.
RE: Plastic Bevel Gear Design
Here's some nice info about the shape of teeth:
https://books.google.com/books?id=iauMTmKxfBoC&...
There are three main standards- octoid, arc and spherical involute. Octoid has sub types- e.g. flat root or concave root, line and/or profile crowning, generated or formate. Arc is typically used with bigger profile angles and used for differential gears, tooth shape comes from the tooling manufacturer. Spherical involute is easy to model, general (spherical involute can be defined with few parameters, just as the planar involute) and is used by flank generators for the end milling.
The real geometry comes from the teeth making technology, the main thing is that the meshing should be correct in terms of contact pattern and transmission error.
The gear shop will typically make the electrode for EDM with the technology available to them, so the exact tooth shape is not your concern, right?
RE: Plastic Bevel Gear Design
RE: Plastic Bevel Gear Design
RE: Plastic Bevel Gear Design
H
www.tynevalleyplastics.co.uk
Politicians like to panic, they need activity. It is their substitute for achievement.
RE: Plastic Bevel Gear Design
RE: Plastic Bevel Gear Design
Might be of some use.
H
www.tynevalleyplastics.co.uk
Politicians like to panic, they need activity. It is their substitute for achievement.