cadquery创建螺纹thread

参考来源: https://github.com/CadQuery/cadquery/issues/407

import math
import cadquery as cq


def profile(base, pitch, h, extra=True):
    """
pitch 螺距
    Creates a trapezoidal wire for the cross section of the thread. If the
    cross section only goes out to the major diameter, then it doesn't cut a
    cylinder for some reason. Set extra=True to extend the cross section beyond
    the major diameter, to be certain it clears the outer surface of the base
    cylinder.
    """
    vertices = [
        base + cq.Vector(-5 / 8 * h, 0, -pitch / 8)
        , base + cq.Vector(0, 0, -7 / 16 * pitch)
    ]
    if extra:
        vertices.extend([
            base + cq.Vector(h, 0, -7 / 16 * pitch)
            , base + cq.Vector(h, 0, 7 / 16 * pitch)
        ])
    vertices.extend([
        base + cq.Vector(0, 0, 7 / 16 * pitch)
        , base + cq.Vector(-5 / 8 * h, 0, pitch / 8)
    ])
    vertices.append(vertices[0])
    return vertices


def thread_solid(pitch=3.5, major_diam=30+1e-4, length=10, included_angle=60, offset=0):
    """
    Makes a solid representing a metric thread. Can be unioned to a tube with
    ID == major_diam to make an internal thread, or cut from a cylinder with
    OD == major_diam for an external thread. If offset != 0, then the profile
    is offset before sweeping, which can be used to add clearance.
    """
    h = pitch / (2 * math.tan(included_angle / 2 * math.pi / 180))
    base = cq.Vector(major_diam / 2, 0, 0)
    vertices = profile(base, pitch, h)
    profile_wire = cq.Wire.makePolygon(vertices)
    if offset:
        profile_wire = profile_wire.offset2D(offset)[0]  # offset2d returns a list, we need the one and only wire returned
    # make the helical path to sweep
    path = cq.Wire.makeHelix(pitch, length + 2 * pitch, major_diam / 2, center=cq.Vector(0, 0, -pitch))
    thread = cq.Solid.sweep(profile_wire, [], path, isFrenet=True)
    print(thread.isValid())
    return thread


thread = thread_solid(length=20)
screw = (
    cq
    .Workplane(origin=(0, 0, -5))  # make sure the thread cutting tool extends below the screw
    .circle(30 / 2)
    .extrude(30)  # make sure the thread cutting toold extends above the screw
    .cut(thread,clean=False)
)

screw = (
    screw
    .faces('<Z').workplane(offset=-10).split(False,True)
    .faces('<Z').workplane(offset=-10).split(True)
)

1. profile 函数:

   • profile 函数用于创建螺纹横截面的轮廓。它的参数包括 base（基准点），pitch（螺距），h（梯形的高度）和 extra（一个布尔值，控制是否扩展轮廓以确保清除基础圆柱体的外表面）。
   • 该函数计算并返回一个包含横截面轮廓顶点坐标的列表，这些顶点定义了梯形的形状。

2. thread_solid 函数:

   • thread_solid 函数用于创建表示度量螺纹的实体。可以将这个实体与具有内径等于 major_diam 的管道进行合并，以创建内部螺纹，或者从具有外径等于 major_diam 的圆柱体中进行切割，以创建外部螺纹。offset 参数用于控制轮廓是否在扫描之前进行偏移以添加间隙。
   • 该函数使用 profile 函数创建螺纹的横截面轮廓，然后使用 cq.Wire.makeHelix 创建一个螺旋路径，最后使用 Solid.sweep 函数将横截面轮廓沿着螺旋路径进行扫描以创建螺纹实体。

3. 在接下来的代码部分，螺纹实体被切割以创建一个螺纹工具。切割工具由一个圆柱体组成，用于在后续步骤中切割螺纹。

4. 最后，使用 cq.Workplane 创建一个工作平面，该平面从螺纹工具的底部开始，然后在螺纹工具上创建一个圆形。接着，使用 extrude 创建一个立体图形，然后使用 cut 将这个立体图形切割螺纹，从而创建一个带有螺纹的螺栓。接着对螺栓进行分割操作以将其切成一定长度。