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Merge pull request #8934 from jbaehr/partdesign-ingolutegear-profileshift

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PD: Implement Profile Shift for InvoluteGear
This commit is contained in:
Uwe
2023-03-18 00:48:44 +01:00
committed by GitHub
parent 5e6a63be24 e05231aa7f
commit 95087132a2
4 changed files with 200 additions and 16 deletions
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10
src/Mod/PartDesign/InvoluteGearFeature.py
View File

@@ -122,13 +122,17 @@ class _InvoluteGear:
doc=QtCore.QT_TRANSLATE_NOOP("App::Property",
"The radius of the fillet at the root of the tooth, normalized by the module."),
default=lambda: 0.375 if is_restore else 0.38)
ensure_property("App::PropertyFloat","ProfileShiftCoefficient",
doc=QtCore.QT_TRANSLATE_NOOP("App::Property",
"The distance by which the reference profile is shifted outwards, normalized by the module."),
default=0.0)
def execute(self,obj):
w = fcgear.FCWireBuilder()
generator_func = involute.CreateExternalGear if obj.ExternalGear else involute.CreateInternalGear
generator_func(w, obj.Modules.Value, obj.NumberOfTeeth, obj.PressureAngle.Value,
split=obj.HighPrecision, addCoeff=obj.AddendumCoefficient, dedCoeff=obj.DedendumCoefficient,
filletCoeff=obj.RootFilletCoefficient)
filletCoeff=obj.RootFilletCoefficient, shiftCoeff=obj.ProfileShiftCoefficient)
gearw = Part.Wire([o.toShape() for o in w.wire])
obj.Shape = gearw
obj.positionBySupport()
@@ -199,6 +203,7 @@ class _InvoluteGearTaskPanel:
self.form.doubleSpinBox_Addendum.valueChanged.connect(assignValue("AddendumCoefficient"))
self.form.doubleSpinBox_Dedendum.valueChanged.connect(assignValue("DedendumCoefficient"))
self.form.doubleSpinBox_RootFillet.valueChanged.connect(assignValue("RootFilletCoefficient"))
self.form.doubleSpinBox_ProfileShift.valueChanged.connect(assignValue("ProfileShiftCoefficient"))
self.update()
@@ -222,6 +227,7 @@ class _InvoluteGearTaskPanel:
assign("AddendumCoefficient", self.form.doubleSpinBox_Addendum, self.form.label_Addendum)
assign("DedendumCoefficient", self.form.doubleSpinBox_Dedendum, self.form.label_Dedendum)
assign("RootFilletCoefficient", self.form.doubleSpinBox_RootFillet, self.form.label_RootFillet)
assign("ProfileShiftCoefficient", self.form.doubleSpinBox_ProfileShift, self.form.label_ProfileShift)
def changeEvent(self, event):
if event == QtCore.QEvent.LanguageChange:
@@ -237,6 +243,7 @@ class _InvoluteGearTaskPanel:
self.obj.AddendumCoefficient = self.form.doubleSpinBox_Addendum.value()
self.obj.DedendumCoefficient = self.form.doubleSpinBox_Dedendum.value()
self.obj.RootFilletCoefficient = self.form.doubleSpinBox_RootFillet.value()
self.obj.ProfileShiftCoefficient = self.form.doubleSpinBox_ProfileShift.value()
def transferFrom(self):
"Transfer from the object to the dialog"
@@ -248,6 +255,7 @@ class _InvoluteGearTaskPanel:
self.form.doubleSpinBox_Addendum.setValue(self.obj.AddendumCoefficient)
self.form.doubleSpinBox_Dedendum.setValue(self.obj.DedendumCoefficient)
self.form.doubleSpinBox_RootFillet.setValue(self.obj.RootFilletCoefficient)
self.form.doubleSpinBox_ProfileShift.setValue(self.obj.ProfileShiftCoefficient)
def getStandardButtons(self):
return int(QtGui.QDialogButtonBox.Ok) | int(QtGui.QDialogButtonBox.Cancel)| int(QtGui.QDialogButtonBox.Apply)

27
src/Mod/PartDesign/InvoluteGearFeature.ui
View File

@@ -6,8 +6,8 @@
<rect>
<x>0</x>
<y>0</y>
<width>248</width>
<height>270</height>
<width>253</width>
<height>301</height>
</rect>
</property>
<property name="windowTitle">
@@ -233,6 +233,29 @@
</property>
</widget>
</item>
<item row="8" column="0">
<widget class="QLabel" name="label_ProfileShift">
<property name="text">
<string>Profile Shift Coefficient</string>
</property>
</widget>
</item>
<item row="8" column="1">
<widget class="QDoubleSpinBox" name="doubleSpinBox_ProfileShift">
<property name="minimum">
<double>-3.000000000000000</double>
</property>
<property name="maximum">
<double>3.000000000000000</double>
</property>
<property name="singleStep">
<double>0.100000000000000</double>
</property>
<property name="value">
<double>0.000000000000000</double>
</property>
</widget>
</item>
</layout>
</widget>
<customwidgets>

140
src/Mod/PartDesign/PartDesignTests/TestInvoluteGear.py
View File

@@ -21,8 +21,10 @@
import unittest
import pathlib
from math import pi, tan, cos, acos
import FreeCAD
Quantity = FreeCAD.Units.Quantity # FIXME from FreeCAD.Units import Quantity doesn't work
from FreeCAD import Vector
from Part import makeCircle, Precision
import InvoluteGearFeature
@@ -150,6 +152,66 @@ class TestInvoluteGear(unittest.TestCase):
self.assertNoIntersection(hub.Shape, makeCircle(tip_diameter/2 - delta), "Teeth extent below tip circle")
self.assertNoIntersection(hub.Shape, makeCircle(root_diameter/2 + delta), "Teeth extend beyond root circle")
def testShiftedExternalGearProfile(self):
gear = InvoluteGearFeature.makeInvoluteGear('InvoluteGear')
gear.NumberOfTeeth = 9 # odd number to have a tooth space on the negative X-axis
gear.ProfileShiftCoefficient = 0.6
self.assertSuccessfulRecompute(gear)
self.assertClosedWire(gear.Shape)
# first, verify the radial dimensions
xm = gear.ProfileShiftCoefficient * gear.Modules
Rref = gear.NumberOfTeeth * gear.Modules / 2
Rtip = Rref + gear.AddendumCoefficient * gear.Modules + xm
Rroot = Rref - gear.DedendumCoefficient * gear.Modules + xm
delta = Quantity("20 um") # 20 micron is as good as it gets
self.assertIntersection(gear.Shape, makeCircle(Rref), "Expecting intersection at reference circle")
self.assertNoIntersection(gear.Shape, makeCircle(Rtip + delta), "Teeth extent beyond tip circle")
self.assertNoIntersection(gear.Shape, makeCircle(Rroot - delta), "Teeth extend below root circle")
# to verify the angular dimensions, we use an "over pin measurement"
Dpin, Rc = external_pin_diameter_and_distance(
z=gear.NumberOfTeeth,
m=gear.Modules.getValueAs('mm'),
a=gear.PressureAngle.getValueAs('rad'),
x=gear.ProfileShiftCoefficient)
Rpin = Quantity(f"{Dpin/2} mm")
delta = Quantity("1 um") # our angular precision is much greater then the radial one
self.assertIntersection(gear.Shape, makeCircle(Rpin + delta, Vector(-Rc)),
msg="Expecting intersection with enlarged pin")
self.assertNoIntersection(gear.Shape, makeCircle(Rpin - delta, Vector(-Rc)),
msg="Expecting no intersection with reduced pin")
def testShiftedInternalGearProfile(self):
gear = InvoluteGearFeature.makeInvoluteGear('InvoluteGear')
gear.NumberOfTeeth = 11 # odd number to have a tooth space on the negative X-axis
gear.ExternalGear = False # to ensure "clean" flanks we need to tweak some more props
gear.ProfileShiftCoefficient = 0.4
gear.AddendumCoefficient = 0.6
gear.DedendumCoefficient = 0.8
self.assertSuccessfulRecompute(gear)
self.assertClosedWire(gear.Shape)
# first, verify the radial dimensions
xm = gear.ProfileShiftCoefficient * gear.Modules
Rref = gear.NumberOfTeeth * gear.Modules / 2
# For internal, too, positive shift is outwards. So this is *not* inverted.
Rtip = Rref - gear.AddendumCoefficient * gear.Modules + xm
Rroot = Rref + gear.DedendumCoefficient * gear.Modules + xm
delta = Quantity("20 um") # 20 micron is as good as it gets
self.assertIntersection(gear.Shape, makeCircle(Rref), "Expecting intersection at reference circle")
self.assertNoIntersection(gear.Shape, makeCircle(Rtip - delta), "Teeth extent below tip circle")
self.assertNoIntersection(gear.Shape, makeCircle(Rroot + delta), "Teeth extend beyond root circle")
# to verify the angular dimensions, we use an "over pin measurement"
Dpin, Rc = internal_pin_diameter_and_distance(
z=gear.NumberOfTeeth,
m=gear.Modules.getValueAs('mm'),
a=gear.PressureAngle.getValueAs('rad'),
x=gear.ProfileShiftCoefficient)
Rpin = Quantity(f"{Dpin/2} mm")
delta = Quantity("1 um") # our angular precision is much greater then the radial one
self.assertIntersection(gear.Shape, makeCircle(Rpin + delta, Vector(-Rc)),
msg="Expecting intersection with enlarged pin")
self.assertNoIntersection(gear.Shape, makeCircle(Rpin - delta, Vector(-Rc)),
msg="Expecting no intersection with reduced pin")
def testZeroFilletExternalGearProfile_BaseAboveRoot(self):
gear = InvoluteGearFeature.makeInvoluteGear('InvoluteGear')
# below 42 teeth, with default dedendum 1.25, we have some non-involute flanks
@@ -261,3 +323,81 @@ class TestInvoluteGear(unittest.TestCase):
def assertSolid(self, shape, msg=None):
self.assertEqual(shape.ShapeType, 'Solid', msg=msg)
def inv(a):
"""the involute function"""
return tan(a) - a
def external_pin_diameter_and_distance(z, m, a, x):
"""Calculates the ideal pin diameter for over pins measurement and its distance
for extrnal spur gears.
z is the number of teeth
m is the module, in millimeter
a is the pressure angle, in radians
x is the profile shift coefficient
returns the tuple of ideal pin diameter and its center distance from the gear's center
"""
# Equations taken from http://qtcgears.com/tools/catalogs/PDF_Q420/Tech.pdf
# Table 10-13 (1-4) and Table 10-14 (4a)
# 1. Half Tooth Space Angle at Base Circle
nu = pi / (2 * z) - inv(a) - 2 * x * tan(a) / z
# 2. The Pressure Angle at the Point Pin is Tangent to Tooth Surface
ap = acos(z * m * cos(a) / (z * m + 2 * x * m))
# 3. The Pressure Angle at Pin Center
phi = tan(ap) + nu
# 4. Ideal Pin Diameter
dp = z * m * cos(a) * (inv(phi) + nu)
# 4a. Over Pins Measurement, even number of teeth
# As we return the distance from the gear's center, we need dm to pass thought this center
# and that's only the case for a dm for an even number of teeth. However, this center distance
# is also valid for an odd number of teeth, as we don't measure pin-to-pin but pin-to-center.
dm = z * m * cos(a) / cos(phi) + dp
# Eq. 10-12 on page T46
rc = (dm - dp) / 2
return (dp, rc)
def internal_pin_diameter_and_distance(z, m, a, x):
"""Calculates the ideal pin diameter for over pins measurement and its distance
for intrnal spur gears.
z is the number of teeth
m is the module, in millimeter
a is the pressure angle, in radians
x is the profile shift coefficient
returns the tuple of ideal pin diameter and its center distance from the gear's center
"""
# Equations taken from http://qtcgears.com/tools/catalogs/PDF_Q420/Tech.pdf
# Table 10-17 (1-4) and Table 10-18 (4a)
# 1. Half Tooth Space Angle at Base Circle
nu = pi / (2 * z) + inv(a) + 2 * x * tan(a) / z
# 2. The Pressure Angle at the Point Pin is Tangent to Tooth Surface
ap = acos(z * m * cos(a) / (z * m + 2 * x * m))
# 3. The Pressure Angle at Pin Center
phi = tan(ap) - nu
# 4. Ideal Pin Diameter
dp = z * m * cos(a) * (nu - inv(phi))
# 4a. Over Pins Measurement, even number of teeth
# As we return the distance from the gear's center, we need dm to pass thought this center
# and that's only the case for a dm for an even number of teeth. However, this center distance
# is also valid for an odd number of teeth, as we don't measure pin-to-pin but pin-to-center.
dm = z * m * cos(a) / cos(phi) - dp
rc = (dm + dp) / 2
return (dp, rc)

39
src/Mod/PartDesign/fcgear/involute.py
View File

@@ -23,14 +23,15 @@
# License along with FCGear; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
from math import cos, sin, pi, acos, asin, atan, sqrt, radians
from math import cos, sin, tan, pi, acos, asin, atan, sqrt, radians
from math import comb as binom
def CreateExternalGear(w, m, Z, phi,
split=True,
addCoeff=1.0, dedCoeff=1.25,
filletCoeff=0.375):
filletCoeff=0.375,
shiftCoeff=0.0):
"""
Create an external gear
@@ -43,6 +44,7 @@ def CreateExternalGear(w, m, Z, phi,
filletCoeff is the root fillet radius, normalized by the module.
The default of 0.375 matches the hard-coded value (1.5 * 0.25) of the implementation
up to v0.20. The ISO Rack specified 0.38, though.
shiftCoeff is the profile shift coefficient (profile shift normalized by module)
if split is True, each profile of a teeth will consist in 2 Bezier
curves of degree 3, otherwise it will be made of one Bezier curve
@@ -56,13 +58,15 @@ def CreateExternalGear(w, m, Z, phi,
split_involute=split,
outer_height_coefficient=addCoeff,
inner_height_coefficient=dedCoeff,
inner_fillet_coefficient=filletCoeff)
inner_fillet_coefficient=filletCoeff,
profile_shift_coefficient=shiftCoeff)
def CreateInternalGear(w, m, Z, phi,
split=True,
addCoeff=0.6, dedCoeff=1.25,
filletCoeff=0.375):
filletCoeff=0.375,
shiftCoeff=0.0):
"""
Create an internal gear
@@ -81,6 +85,7 @@ def CreateInternalGear(w, m, Z, phi,
filletCoeff is the root fillet radius, normalized by the module.
The default of 0.375 matches the hard-coded value (1.5 * 0.25) of the implementation
up to v0.20. The ISO Rack specified 0.38, though.
shiftCoeff is the profile shift coefficient (profile shift normalized by module)
if split is True, each profile of a teeth will consist in 2 Bezier
curves of degree 3, otherwise it will be made of one Bezier curve
@@ -95,7 +100,8 @@ def CreateInternalGear(w, m, Z, phi,
rotation=pi/Z, # rotate by half a tooth to align the "inner" tooth with the X-axis
outer_height_coefficient=dedCoeff,
inner_height_coefficient=addCoeff,
outer_fillet_coefficient=filletCoeff)
outer_fillet_coefficient=filletCoeff,
profile_shift_coefficient=shiftCoeff)
def _create_involute_profile(
@@ -108,7 +114,8 @@ def _create_involute_profile(
outer_height_coefficient=1.0,
inner_height_coefficient=1.0,
outer_fillet_coefficient=0.0,
inner_fillet_coefficient=0.0):
inner_fillet_coefficient=0.0,
profile_shift_coefficient=0.0):
"""
Create an involute gear profile in the given wire builder
@@ -125,8 +132,9 @@ def _create_involute_profile(
The "_coefficient" suffix denotes values normalized by the module.
"""
outer_height = outer_height_coefficient * module # external: addendum, internal: dedendum
inner_height = inner_height_coefficient * module # external: dedendum, internal: addednum
profile_shift = profile_shift_coefficient * module
outer_height = outer_height_coefficient * module + profile_shift # ext: addendum, int: dedednum
inner_height = inner_height_coefficient * module - profile_shift # ext: dedendum, int: addednum
# ****** calculate radii
# All distances from the center of the profile start with "R".
@@ -248,8 +256,13 @@ def _create_involute_profile(
else:
inv = BezCoeffs(Rb, Rfo, 4, fs, fe)
# ****** calculate angular tooth thickness at reference circle
enlargement_by_shift = profile_shift * tan(pressure_angle) / Rref
tooth_thickness_half_angle = angular_pitch / 4 + enlargement_by_shift
psi = tooth_thickness_half_angle # for the formulae below, a symbol is more readable
# rotate all points to make the tooth symetric to the X axis
inv = [rotate(pt, -base_to_ref - angular_pitch / 4) for pt in inv]
inv = [rotate(pt, -base_to_ref - psi) for pt in inv]
# create the back profile of tooth (mirror image on X axis)
invR = [mirror(pt) for pt in inv]
@@ -257,12 +270,12 @@ def _create_involute_profile(
# ****** calculate section junction points.
# Those are the points where the named element ends (start is the end of the previous element).
# Suffix _back is back of this tooth, suffix _next is front of next tooth.
inner_fillet = toCartesian(Rfi, -angular_pitch / 4 - start_to_ref) # top of fillet
inner_fillet = toCartesian(Rfi, -psi - start_to_ref) # top of fillet
inner_fillet_back = mirror(inner_fillet) # flip to make same point on back of tooth
inner_circle_back = toCartesian(Ri, angular_pitch / 4 + start_to_ref + inner_fillet_angle)
inner_circle_next = toCartesian(Ri, 3 * angular_pitch / 4 - start_to_ref - inner_fillet_angle)
inner_circle_back = toCartesian(Ri, psi + start_to_ref + inner_fillet_angle)
inner_circle_next = toCartesian(Ri, angular_pitch - psi - start_to_ref - inner_fillet_angle)
inner_fillet_next = rotate(inner_fillet, angular_pitch) # top of fillet, front of next tooth
outer_fillet = toCartesian(Ro, -angular_pitch / 4 + ref_to_stop + outer_fillet_angle)
outer_fillet = toCartesian(Ro, -psi + ref_to_stop + outer_fillet_angle)
outer_circle = mirror(outer_fillet)
# ****** build the gear profile using the provided wire builder