Creating a model by using cutting action simulation 1

[Spurs]

I am trying to create a model of a very complicated gear geometry. (Its a face gear) The geometry cannot be easily defined by standard geometric equations.

In the real world, to create this face gear, a spur gear shaped cutter is mounted at right angles to the face gear blank. The cutter is then revolved at a controlled speed relative to the workpiece.

So there is a combination involved of moving the workpiece (roatationally) at some indexing relationship to the rotation of the cutter.

Modeling the spur gear cutter is no problem. Modeling the face gear blank is no problem.
Can the final face gear profile be modeled in solidworks with some sort of technique that resemles the manufacturing process? I am not interested in visually simulating the machining operation. I am only interested in the final model of the face gear.

 

[SnowCrash]

I have done something close to this. Create your base part and place it in an assembly. Create a new solid part which is essentially the cutting tool. Move copies of the cutting tool into the cutting tool path and create a new solid tool part which represents the cut.
Use your mold tools to create a cavity in the base part which is the cut you want. Step and repeat as neccesary.
--
Crashj

 

[mncad]

Spurs,

I don't think there is a good way to accomplish this. It is an enhancement request that I have turned in though. To be able to create a sweep cut using a 3d sketch for the toolpath and a solid as the cutting tool. I'm not sure about how Snowcrash is saying to do it, seems like you would need alot of copies of the cutting tool to make it work right and even then it wouldn't be exactly right.

mncad

 

[rporter]

Spurs,

if you know the number of teeth on the gear start with the mold cavity as SnowCrash stated above but use a pattern of the cavity instead of repeating the process this will save a little time.

 

[krywarick6]

Is it similar to a bevel gear, only having a pitch cone angle which is 90° or perpendicular to the center/hub axis?

Why not take a look at the SW Services and Support site? Login and guide to Support/Downloads/Model Library/Parts/Gears, Sprockets and Power Trans and scroll down to "Bevel2.zip".

This may help conceptualize what you are trying to achieve.

Christopher Zona
Litens Automotive Partnership
Concord, Ontario, Canada

 

[drawoh]

Spurs,

I take you are trying to model an involute. My copy of Dudley's Gear Handbook Second Edition, Dennis P. Townsend, McGraw Hill, has instructions on how to approximate an involute. Check out their section on Gear Drawings. I used their procedure to test 3D CAD packages. It turned out to be an effective piece of software abuse.

Also, I have a copy of Engineering Drawings, by Thomas E. French, McGraw Hill. My copy is dated 1941, so I doubt this is in print anymore. I paid ten dollars Canadian for it in a second hand book store. It has a section entitled "How to Draw a Spur Gear". I have not tried out their technique, so I cannot vouch for it.

I suggest that you look around for some old drafting books. I knew about my Dudley's Gear Handbook. The other book took me five minutes to search.

JHG

 

[EdDanzer]

Camnetics, Inc. has the GearTrax add in for sprocket and gear design. It seems to work fine and the files are not to large.

 

[Spurs]

Drawoh
I am not trying to produce an involute - thats no problem

EdDanzer
I tried the GearTrax software - it makes a picture but is totally inaccuate to actually machine anything with it - the main problem with GearTrax is that it treats helical gears like spur gears from a calculation point of view which is totally wrong - it looks to me like it was developed by software guys who dont know gearing

To draw and design gears, I use Web Gear Services software

http://members.rogers.com/webgear/software.htm

but for this problem, I am trying to create an accurate model of a face gear which has some similarities to bevels

krywarick6
I am familiar with the bevel gear example. It is not quiet the same thing that I am looking for. In that example, a loft cut is done using a sketched profile. The sketched profile lookis like it was developed by some other software.

What I am trying to do, is take several of these profiles in small increments of rotation (on the cutter axis) and then do multiple loft cuts just to define 1 tooth of the face gear. It seams to me that some sort of macro can do this but I am not familiar how to do that.

 

[Theophilus]

If I'm getting this correctly, I would think a loosely-defined sweep cut would work much more effectively than any sort of loft. You can use multiple guide curves (conically helical if you like) and a loosely-defined profile will allow your cut to vary slightly along the path while following your guide curves.

The tough part is figuring out exactly where your guide curves need to be to properly define your edges/surfaces. However, if you've got that behind you, the cut itself shouldn't be a problem.




Jeff Mowry
Industrial Designhaus, LLC

http://www.industrialdesignhaus.com

 

[TheTick]

Spurs:

re: "...the main problem with GearTrax is that it treats helical gears like spur gears from a calculation point of view which is totally wrong..."

I haven't seen GearTrax. Still, I'm curious what you mean by this. Could you elaborate?

"Great ideas need landing gear as well as wings."--C. D. Jackson

http://www.EsoxRepublic.com

 

[Spurs]

TheTick

Very simple

The standard pitch diameter of a spur gear (in metric units) is # of teeth x module

Therefore if the gear is module 1 with 20 teeth, the standard pitch diameter is 20 mm

In a helical gear, the standard pitch diameter is
# of teeth x module / cos(Helix Angle)

Therefore a module 1 - 20 tooth helical gear with a 10 degree helix angle would have a standard pitch diameter of 20.309 mm

Gear trax would draw the helical gear with a 20.0 mm pitch diamter - which means that the tooth thickness in the model would be wrong because it is taken at the wrong diameter,

 

[TheTick]

Interesting.

Thanks, Spurs.

 

[SBaugh]

You should send this to the creator of Geartrax

http://www.camnetics.com

Regards,

Scott Baugh, CSWP

http://www.3dvisiontech.com

http://www.scottjbaugh.com

faq731-376

 

[Spurs]

Scott

I learned this through their demo on their web site. Maybe they would send me a full package to look at.

 

[SBaugh]

Can't hurt to ask

Regards,

Scott Baugh, CSWP

http://www.3dvisiontech.com

http://www.scottjbaugh.com

faq731-376

 

[Dennyd]

Scott, your emoticon looks like a Borg that needs a haircut!! Very cool.

And now for what we call "The Vulcan Conundrum":
If a Vulcan were to conclude that science fiction was illogical, would he cease to exist?

(Just starting the new year off with some fun!)

- - -Dennyd