CADquery 螺纹的绘制

from cadquery import *
import cadquery as cq
from math import *


def helix(r0, r_eps, p, h, d=0, frac=1e-1):
    def func(t):

        if frac < t < 1 - frac:
            z = h * t + d
            r = r0 + r_eps
        elif t <= frac:
            z = h * t + d * sin(pi / 2 * t / frac)
            r = r0 + r_eps * sin(pi / 2 * t / frac)
        else:
            z = h * t - d * sin(2 * pi - pi / 2 * (1 - t) / frac)
            r = r0 - r_eps * sin(2 * pi - pi / 2 * (1 - t) / frac)

        x = r * sin(-2 * pi / (p / h) * t)
        y = r * cos(2 * pi / (p / h) * t)

        return x, y, z

    return func


def thread(radius, pitch, height, d, radius_eps, aspect=10):
    e1_bottom = (cq.Workplane("XY")
                 .parametricCurve(helix(radius, 0, pitch, height, -d)).val()
                 )
    e1_top = (cq.Workplane("XY")
              .parametricCurve(helix(radius, 0, pitch, height, d)).val()
              )

    e2_bottom = (cq.Workplane("XY")
                 .parametricCurve(helix(radius, radius_eps, pitch, height, -d / aspect)).val()
                 )
    e2_top = (cq.Workplane("XY")
              .parametricCurve(helix(radius, radius_eps, pitch, height, d / aspect)).val()
              )

    f1 = Face.makeRuledSurface(e1_bottom, e1_top)
    f2 = Face.makeRuledSurface(e2_bottom, e2_top)
    f3 = Face.makeRuledSurface(e1_bottom, e2_bottom)
    f4 = Face.makeRuledSurface(e1_top, e2_top)

    sh = Shell.makeShell([f1, f2, f3, f4])
    rv = Solid.makeSolid(sh)

    return rv


radius = 4
pitch = 2
height = 4
d = pitch / 4
radius_eps = 0.5
eps = 1e-3

core = cq.Workplane("XY", origin=(0, 0, -d)).circle(4).circle(3).extrude(height + 1.75 * d)
th1 = thread(radius - eps, pitch, height, d, radius_eps)
th2 = thread(radius - 1 + eps, pitch, height, d, -radius_eps)

res = core.union(Compound.makeCompound([th1, th2]))