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US 4,588,336 AGranted
Rack and pinion gear and process of fabrication
OwnerBernard J. Navarroinventor
Life of this patent
Estimating the term…
Abstract
A rack and pinion gear having helical teeth. A conical hob is employed for cutting recessed rack teeth in the work piece by continuously engaging the hob and work piece as the work piece moves longitudinally beneath (or with respect to) the rotating hob. To mate with the helical teeth in the rack, a helical gear having rounded or arcuate teeth is provided.
Claims5
Process for cutting rack teeth having arcuate roots comprising:
- providing a rotatably mounted, conical hob with a substantially uniform semi vertical angle along its entire length and having teeth formed on a helix;
- providing an elongate work piece generally parallel to the axis of the hob;
- rotating the hob about its axis
- longitudinally moving the hob and work piece relative to each other in synchronism with hob rotation, and at a rate dependent upon hob lead;
- engaging the smaller end of the hob with the work piece;
- continuing the relative longitudinal movement to cause hob teeth of continuously increasing diameter to cut into the work piece, until the hob has passed completely over the work piece;
- thereby forming in the work piece, generally transverse, arcuate, parallel grooves constituting recessed, concave, arcuate roots of rack teeth.
4 more elements
A conical hob comprising:
- a hob body with a conical face having a substantially uniform semivertical angle along its entire length;
- at least one helical thread or ridge substantially surrounding said face;
- said thread having its crest lying on said conical face, and having its root lying on a cylinder formed about the hob axis;
- a plurality of flutes or gashes passing through said helical ridge, generally parallel to the hob axis, and forming the cutting teeth of the hob;
- the leading edges of said teeth facing said flutes constituting the cutting edges of the hob;
- said flutes constituting chip collection regions where chips cut from a work piece gather.
3 more elements
Dependencies are inferred from the claim text.