C-Open Collar

```python import FreeCAD as App import Part import math # ========================================== # C口项圈三维建模 # 单位：mm # ========================================== DOC_NAME = "C_Open_Collar" doc = App.newDocument(DOC_NAME) # ---------- 基础尺寸 ---------- INNER_DIAMETER = 140.0 CENTER_WIDTH = 35.0 END_WIDTH = 8.0 THICKNESS = 1.2 OPENING_GAP = 60.0 FLARE_ANGLE_DEG = 31.0 R_INNER = INNER_DIAMETER / 2.0 R_MID = R_INNER + THICKNESS / 2.0 # ---------- C形圆弧 ---------- # 开口位于后方，保留60mm间距 half_angle = math.degrees( math.asin(min(OPENING_GAP / (2.0 * R_MID), 0.99)) ) start_angle = 90.0 + half_angle end_angle = 450.0 - half_angle # 从一侧端头绕过前方，到另一侧端头 arc_points = [] steps = 120 for i in range(steps + 1): t = i / steps angle = math.radians( start_angle + (end_angle - start_angle) * t ) x = R_MID * math.cos(angle) y = R_MID * math.sin(angle) arc_points.append(App.Vector(x, y, 0)) spine = Part.BSplineCurve() spine.interpolate(arc_points) spine_edge = spine.toShape() # ---------- 沿圆弧构造变化宽度的实体 ---------- # 截面在局部平面内构造，宽度由端头8mm渐变至中央35mm sections = [] section_count = 60 for i in range(section_count + 1): t = i / section_count # 两端窄，中间宽，采用平滑余弦过渡 profile_factor = (1.0 - math.cos(2.0 * math.pi * t)) / 2.0 width = END_WIDTH + ( CENTER_WIDTH - END_WIDTH ) * profile_factor angle = math.radians( start_angle + (end_angle - start_angle) * t ) # 径向方向 radial = App.Vector(math.cos(angle), math.sin(angle), 0)

Parameters

Every value above is a live dimension. Open a model like this in the editor and each one becomes a slider you can drag before exporting.