Gear and rack rolling generation software

[gearman1234]

I was just wondering if there is any software out there which could be used to test the rolling of rack and a gear of known data.

WE are having gear and a rack of 14.5 degree Pressure angle and 20 DP but do not seem to roll properly. Individually both are good in dimensions but seem to have problem rolling together.

Any information is appreciated.

 

[EnglishMuffin]

What's the known data ? If there is an inconsistency in it, it should be fairly obvious even without software. Of course, the problem probably lies with the data that you don't know.

 

[diamondjim]

How was the gear generated? If it
was rack or hob generated it should
mesh ok with the rack profile. If
the gear were shaped you would find
problems with the mesh.

 

[gearman1234]

The gear data is 28 T, 20 DP , 14.5 deg PA.Ofcourse the rack is of the same data. I checked the gear and is having pressure angle error on one flank 0.002" instead of 0.0008" required. The measurement over pins for the gear is OK. 0.001" to 0.003" backlash. Pitch error 0.0005".

Rack obviously of the same design data. I can check the Measurement over pins for the rack and it is 0.005 under than required. The full depth is 0.1125". I can not check the pressure angle or pitch error of the rack .

Gear is hobbed and rack is probably shaped.

Is it wrong to assume that 14.5 deg pressure angle system or this small DP may have inherent roll out problem? I want to check this assumption that 14.5 pressure angle, 20 DP gear meshing wity the rack has a roll out problem.

Theorectically I do not see any reason to have aproblem but practically it seems to have a problem.

 

[EnglishMuffin]

Sounds like you need to check the pressure angle and pitch of the rack - like I said, it's probably the things you don't know that are the problem. You should be able to check pressure angle and pitch error by using various sizes of roller, together with position measuring equipment of some type, for example.

 

[diamondjim]

If the pressure angles of both parts
are the same, they should mesh or roll
correctly. I would check both gear and
rack with another size pin and see if
the different measurements agree with
the change in pins sizes. This would give
you some indication that the gears have
the same pressure angle and pitch to
pitch measurements. I would bet that
the pressure angle for one or the other
is not correct.
You mention that the rack is .005 under.
Are you talking about from some theroretical
plane or surface below its pitch line?

 

[gearman1234]

The 0.005" under is the surface below the rack. I measured the width of rack. One side we have the rack and the other side is the plain surface which acts as a datum. It was as per dwg. Then I measured the size over pins with reference to the bottom surface only.

 

[Gearhead]

Software is available to plot the mesh of gear teeth. see

http://www.uts.com

 

[Spurs]

In order for the gear to mesh with the rack properly, they must have the same base pitch.

The base pitch is affected by the diametral pitch and the pressure angle. Did you do a measuremetn of the base pitch of each to see if you can spot the error that way?

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

 

[gearman1234]

Thanks for input from all of you.

I found that some gears which do not roll properly have burrs on them. We would eliminate this cause first and see for the results.

 

[MooreGear]

Hi there, I work for Moore Gear and Manufacturing. We manufacture thoasands of gears and gear rack using CNC machines. We keep standard sizes of gear rack in stock. We are abe to trouble shoot situations like the one you are having with our CNC gear checker. Also a common cause for the problem you are having is cirular pitch error (improper spacing of the teeth on the rack). If you want to get a hold of me I can be reached at william@mooregear.com

Thanks,
Bill

 

[gearman1234]

Hi William,

Thanks for the information.
The burr generated in hobbing was the main cause of rolling problem. After removing the burr the problem disappeared.
The pitch error in the gears was checked on CNC gear checker and found to be within AGMA 9. However I could not check the rack as we do not have that software.