南京理工大学机械原理chapter6.pptVIP

6.4. Standard Involute Spur Gears addendum circle (or tip circle) （齿顶圆） ----da, ra dedendum circle (or root circle) （齿根圆）----df, rf base circle ----db, rb an arbitrary circle (任意圆) ----di, ri The tooth space (齿槽) ----the space between the profiles of two adjacent(相邻的) teeth. The spacewidth(齿槽宽) ei----the arc length of the tooth space along an arbitrary circle. The tooth thickness (齿厚) si---- the arc length of the tooth along an arbitrary circle. The pitch(齿距，周节) pi ---arc distance between corresponding points of adjacent teeth along an arbitrary circle. pi = ei + si pressure angle ?K Any parameter on the reference circle has no subscript(下标), r, e, s, p, ?=20 ° The module m (模数)---- a basic parameter on the reference circle. Different module needs different cutter. The module m has been standardized. Tab 6-1 modules of Involute Cylindrical Gears  (GB/T1357-1987) Modules of the first series are preferable. The addendum (齿顶高) ha---- radial distance between the reference circle and the addendum circle. The dedendum (齿根高) hf ----radial distance between the reference circle and the dedendum circle. The tooth depth (齿全高) h ----radial distance between the dedendum circle and addendum circle. For standard gears: Base pitch(基节)pb--- the pitch on the base circle. Normal pitch(法节)pn-------The distance between corresponding sides of adjacent tooth profiles along the common normal. Review: The normal distance between two involutes of the same base circle remains the same. The fundamental parameters: 6.4.2 The Rack（齿条） 6.4.3 Internal Gears The tooth thickness ? the tooth space To ensure a continuous transmission, there must exist such situation that two pairs of teeth contact simultaneously(同时地) . the bottom clearance(顶隙) c ： the radial distance from the dedendum circle of one gear to the addendum circle of another Working pressure angle ?’ (啮合角) The meshing begins at point B2, K moves along the line of action and ends at point B1 The segment B1B2