Parametrisches Pfeilrad-Planetengetriebe / Parametric Herringbone Planetary Gear

thingiverse

Parametric Planetary Gear using Involute Tooth Geometry and Herringbone Shape This script calculates both the ring gear as well as the number and geometry of the planetary gears from the number of teeth on the sun and planets. For a module of m, zs teeth for the sun and zp teeth for the planets, the centre distance will be m/2 · (zs + zp) If the number of planets is set to zero, then the script will try and calculate them. For a module of m, zs teeth for the sun, zp teeth for the planets and a rim width of br, the outer diameter is m · (zs+2zp+2.333) + 2br The helix angle should be between 30° and 45°. Recommendations for the helix angle depending on the module can be found in DIN 3978. This script adjusts the pressure angle in the transverse section to the helix angle: e.g. with a 30° helix angle, a pressure angle of 20° becomes a pressure angle of 22.80° in the transverse section. To avoid the gears sticking in a 3D print, particularly sticking of the planet gears to the ring gear, the gears can be printed in disassembled layout (zusammen gebaut = 0). In that case, please note that herringbone teeth complicate the re-assembly. Experience shows that reassembly is still possible at 30°; however in case of reassembly problems, a lesser helix angle should be selected. The gears can also be kept from sticking by a sufficiently large clearance ("Spiel"); a sufficient clearance also avoids meshing problems. Clearance can be left smaller if the 3D printer offers good resolution, however experience shows that it should not be less than 5%. Format: planetengetriebe(modul, zahnzahl_sonne, zahnzahl_planet, breite, randbreite, bohrung, eingriffswinkel=20, schraegungswinkel=0, zusammen_gebaut=true, optimiert=1) Parameters: spiel = clearance between teeth as a fraction of their width (0 = no clearance) modul = gear module = 25.4 / diametrical pitch = circular pitch / pi zahnzahl_sonne = number of teeth on the sun gear zahnzahl_planet = number of teeth per planet gear anzahl_planeten = number of planet gears breite = face width randbreite = width of the rim around the ring gear, measured from the root circle bohrung = central bore diameter eingriffswinkel = pressure angle, standard value = 20° according to DIN 867 schraegungswinkel = helix angle to the rotation axis; 0° = straight teeth zusammen_gebaut = components assembled (= 1) for construction or disassembled (= 0) for 3D printing optimiert = create holes for material/weight reduction resp. surface increase, if geometry allows (= 1 if true)