Typically, the manufactured tooth flanks are not perfect: they exhibit errors:
- along the facewidth, which translate as Spiral
/ Helix angle (fb) and Lengthwise crowning (Cb) errors;
- in the depthwise direction, which translate as Pressure angle (fa) and Profile
crowning (Ca) errors;
- Bias, i.e differences in pressure angle errors at Toe and Heel;
- Twist, i.e. crowning along the Toe Tip to Heel
Fillet diagonal (Ct).
Some errors are caused by the tool that cannot be corrected without a tool modification: typically profile crowning
(Ca); these are not covered here. Other errors are caused by the machine itself, which is especially true of older mechanical
machines, and / or the part installation.
Assuming part installation does not change significantly, Spiral / Helix angle, Pressure
angle, Bias, Twist and Lengthwise crowning errors can be eliminated by the HyGEARS Closed Loop function.
For example, a
Z13 spiral bevel pinion is face-milled on a 5Axis CnC machine. Measurement after the 1st cut shows the following results:
Pressure (fa) and Spiral (fb) angle errors on the Concave flank;
- virtually no Pressure (fa) and Spiral (fb) angle errors on the Convex
- some profile crowning (ca) on the Convex flank and virtually no lengthwise crowning (cb) on either flank;
- significant tooth
thickness error (ThErr).
the application of one Closed Loop iteration, the following result is obtained where virtually all errors, apart from the Profile
crowning (Ca), have been eliminated.
Loop can be used on all HyGEARS supported gear types, whether Face Milled or simply milled.
The figure below illustrates the
data flow when Closed Loop is applied in combination with the HyGEARS 5Axis CnC post-processor.
HyGEARS THE GEAR PROCESSOR ™
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