Posted by Stepan Lunin on January 07, 2010 at 12:28:20:
In Reply to: spiral angle meaurment posted by km on November 27, 2009 at 09:55:52:
Good question! Gleason and Klingelnberg are not offering spiral angle measurement. It is nearly impossible to cut bevel gear on Gleason or on Klingelnberg machines with the spiral angle that is specified on the drawing because of the iterative process of tooth contact development. It is even more difficult to achieve specified spiral angle on both sides of the tooth. It is safe to say that 99.9% of spiral bevel gears from Gleason or Klingelnberg machines have been delivered to the customers with spiral angle different from what it is specified on the drawing. Depending on the accuracy of a gear cutting machine the spiral angle can deviate for a few degrees. But Gleason and Klingelnberg do not want you to measure the angle. They want you to check only the tooth contact. If you start demanding accurate spiral angle the cost of the Gleason and Klingelnberg manufacturing method will increase. This is why more and more people cut gears on 3-axis CNC milling machines. With correct 3d CAD model the CNC milling of gear is more accurate and less expensive compare to gear machining. Spiral Bevel Company provides correct CAD models for CNC milling of spiral bevel gears. With correct spiral bevel gear models and CNC milling inspection of the spiral angle is simple but unnecessary because the tooth surface is measured against a digital master. It is ironic. You would like to measure the spiral angle if the gears are cut on Gleason or on Klingelnberg machines but they do not let you to do so. It is easy to measure spiral angle if you use CNC milling technology, but you do not need to measure the angle because the angle is always correct.
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