工程机械采用变位齿轮较多,其固定弦齿厚和齿高是控制加工精度的重要尺寸。由于计算公式较复杂,不易记住,在施工现场又无处查表。掌握公式的推导方法,就很方便。计算公式是S′_X=m(π/2·cos~2α+(?)·sin2α) (1)h′_X=m(1+(?))-m((π/8)sin2α+(?)·sin~2α)(2)式中S′_X——固定弦齿厚m——模数h′——固定弦齿高(?)——变位系数推导方法:如图1所示,(?)为周节的1/4,即(?)=(mπ)/4,将(?)拉直,其顶点必与齿廓切线相交。这是由渐开线齿轮特性所决定。即渐开线 Construction machinery using more variable gear, the fixed chord thickness and tooth height is an important dimension to control the machining accuracy. As the calculation formula is more complex, not easy to remember, there is no place in the construction site look-up table. Grasp the derivation of the formula, it is very convenient. The calculation formula is: S’_X = m (π / 2 · cos ~ 2α + (?) · Sin2α) h’_X = m (1 + (?)) - m ((π / 8) sin2α + ) · Sin ~ 2α) (2) Where S’_X - fixed chord thickness m - modulus h ’- fixed chord height (?) - Derivation coefficient derivation method: As shown in Figure 1, (?) Is 1/4 of the week, ie (?) = (Mπ) / 4, straighten (?) And its vertex will intersect the tooth profile tangent. This is determined by the involute gear characteristics. That is involute