计算步骤
步骤1: 计算端面模数 m_t = m_n / cos(β) = 2.5 / cos(15°) = 2.588 mm
步骤2: 计算分度圆直径 d = m_t * Z = 2.588 * 20 = 51.76 mm (小齿轮), 2.588 * 30 = 77.65 mm (大齿轮)
步骤3: 计算基圆直径 d_b = d * cos(α_t) = 51.76 * cos(20.65°) = 48.63 mm (小齿轮)
步骤4: 计算齿顶高 h_a = (1 + x) * m_n = (1 + 0) * 2.5 = 2.5 mm
步骤5: 计算齿根高 h_f = (1.25 - x) * m_n = (1.25 - 0) * 2.5 = 3.125 mm
步骤6: 计算齿顶圆直径 d_a = d + 2 * h_a = 51.76 + 2*2.5 = 56.76 mm (小齿轮)