特征生成器

特征生成器

特征生成器将一些工程数字转换为精确的轮廓或啮合：根据模数和齿数计算的渐开线齿轮、根据直径和螺距计算的 ISO 螺纹、根据半径和节距计算的螺旋、根据中心线和厚度计算的弯曲条带。每个都是纯函数 packages/core/src/cad;编辑器、助手和 CAM 模型调用相同的函数，因此三者都会看到相同的部分。

渐开线齿轮

Pitch radius m·z/2, tip radius pitch + m, root radius pitch − 1.25·m, flanks the involute of the base circle r_p·cos α (ISO 53 / DIN 867). The outline is one counter-clockwise ring about the origin with tooth 0 centred on +X. When the teeth would come to a point before the tip circle (few teeth, a large pressure angle), the tip is pulled in by bisection to where the tooth is still 2 % of a pitch wide.

gearOutline({ moduleValue: 2, teeth: 5 })
// RangeError: A gear needs a module > 0 and at least 6 whole teeth
gearOutline({ moduleValue: 2, teeth: 18, pressureAngle: 50 })
// RangeError: The pressure angle must be between 0 and 45 degrees

ISO 公制螺纹

A modelled thread is real helical geometry: a core cylinder at the root united with a ridge swept along a helix with the profile kept radial, clipped to the thread length. External threads have their core at d₃ = d − 1.22687·P and a ridge up to d; internal ones are the tool that cuts a tapped hole, core at D₁ = D − 1.08253·P (the tap drill) and a groove out to D. The flank is cut square to the helix and the axial widths are corrected by the cosine of the helix angle so pitch and crest widths are exact.

值为 threadSizes(d, P, internal) output. Heights are 0.61343·P (external) and 0.54127·P (internal); the crest is P/8.

threadProblem({ diameter: 6, pitch: 4, length: 10, internal: false })
// "A pitch of 4 mm is too coarse for a 6 mm thread"       (pitch > d/2)
threadProblem({ diameter: 6, pitch: 0.1, length: 10, internal: false })
// "A thread has at most 58 turns (this one is 100.0 long: 10 mm at a pitch of 0.1 mm)"
threadProblem({ diameter: 6, pitch: 1, length: 10, internal: false })   // undefined: buildable

58 圈限制为 COIL_MAX_TURNS − 2：脊在螺纹前一螺距开始，在螺纹后一螺距结束，因此平端切削符合整个轮廓。

螺旋

钣金

钣金轮廓是一条中心线加厚为厚度恒定的条带，材料位于左侧、右侧或两侧，每个角都有内部弯曲半径 r。 developedLength unbends it with a K-factor (default 0.44): each bend contributes (r + K·t)·θ and each straight run loses the setback of its neighbouring bends.

{"straight":70,
 "bends":[{"angle":1.5707963267948966,"allowance":6.094689747964199},
          {"angle":1.5707963267948966,"allowance":6.094689747964199}],
 "length":82.18937949592839}

Check: (3 + 0.44 × 2) × π/2 = 6.0947 per bend, and 70 + 2 × 6.0947 = 82.189 mm.

故障排除