Gear rack is a special gear whose teeth are distributed in the strip.
1. The basic concept:
The rack can be split into a spur gear rack and a helical gear rack, which are paired with a spur gear and a helical gear, respectively; the tooth profile of the rack is normally a straight line rather than an involute (planar for the tooth surface) , equivalent to the indexing circle radius is normally infinite cylindrical gear.
2. The main features:
(1) Because the tooth profile of the rack is direct, each point about the tooth profile gets the same pressure angle and is add up to the inclination position of the tooth profile. This angle is named the tooth angle and the standard value is 20°.
(2) The same pitch and modulus are given on the right lines parallel to the top line.
(3) A line parallel to the top type of the tooth and having a tooth thickness equal to the width of the tooth groove is called a dividing line (middle line), which is a reference series for calculating how big is the rack.
3. The main parameters:
Groove width, high tooth tip, high root height, tooth elevation, tooth thickness, root radius, etc.
4. The choice of parameters:
(1) Whether the gear is beating, the entire tooth depth, the common normal line, the tooth direction is qualified, the tooth pitch is poor, and the circumferential section error is out of tolerance.
(2) Whether the installation distance following the gears and racks are installed is suitable.
(3) The rack and gear meshing clearance should be 0.25* modulus.
(4) Whether the complete tooth depth, runout, and common normal type of the rack are experienced.
5. Processing methods:
Gear rack and pinion machining method:
(1) hobbing
(2) gear shaping
(3) shaving
(4) grinding teeth
(5) molars