Abrading – Abrading process – Gear or worm abrading
Patent
1995-05-08
1997-10-28
Rose, Robert A.
Abrading
Abrading process
Gear or worm abrading
451 48, 451147, 451253, 451275, 409 38, 409 51, 409 57, B24B 1504
Patent
active
056812078
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of working a helical gear by grinding with a grindstone, more particularly to a method of working a helical gear capable of obtaining a proper crowing or relieving.
2. Description of the Prior Art
There are various method of working the helical gear such as those by cutting, forging, casting, etc., one of which is the method of working a helical gear by grinding. It is the method of forming a tooth profile by grinding with a grindstone and the following method of working the helical gear by grinding has been well known.
FIGS. 9 and 10 is a view showing the conventionally well-known method of grinding a helical gear.
The helical gear 1 to be ground indexes in the direction of the arrow A and a grindstone 2 is brought into contact therewith to form a tooth profile 3 by grinding. The grindstone 2 rotates on the y-axis (the axis of revolution of the grindstone) and is movable in the directions of the x-axis (the radial direction of the helical gear) and the y-axis (the direction of the tooth trace of the helical gear) in the figure.
In case of forming the tooth profile 3 by grinding with the grindstone 2, the helical gear 1 is turned in the direction of the arrow A by a helix angle while the grindstone 2 is moved in the direction of the z-axis in the figure. Thereafter the helical gear 1 is returned to the original position and the grindstone 2 is slightly displaced in the direction of the x-axis and the helical gear 1 is turned in the direction of the arrow A by the helix angle while the grindstone 2 increased in depth of cut is moved in the direction of the z-axis again. The grinding of the tooth profile 3 is performed by successively repeating this operation. Upon completion of forming a tooth profile 3 by grinding, the helical gear 1 indexes in the direction of the arrow A to allocate the grindstone on the position thereof at which next tooth should be formed, where the aforementioned operation is performed to form the next tooth profile 3 by grinding. The process of grinding the tooth profile 3 is not limited to that described above, but other processes may be employed such as grinding the portions between the teeth of the helical gear 1 bit by bit all over the outer circumference thereof while the helical gear 1 successively indexes so as to gradually deepening the concave portions to form the tooth profiles 3.
FIG. 11 shows an example of a tooth profile 3 which has been formed by grinding in such a way. The tooth profile 3 has the thicknesses D1, D2 and D3 which are respectively same on the contour lines all over the total length thereof in the tooth trace direction indicated by H1, H2 and H3. In case that the tooth profile 3 has the same thickness all over the tooth trace directional length H, there occurs uneven contact between the helical gears 1 when they are engaged each other, which results in the breakage of the tooth profile 3 or the generation of noise in operation.
In order to prevent the breakage of the tooth profile 3 set forth above and reduce the generation of noise, conventional helical gears 1 are provided with crowning or relieving on the tooth profiles 3 thereof. The crowing means the shape of the tooth profile 3 which is modified thinner in thickness (D) at the both ends of the tooth trace directional length H of the tooth profile 3 while gradually thicker toward the center thereof in thickness (D) as illustrated in FIG. 12.
The relieving means the shape of the tooth profile 3 which is modified thinner in thickness (D) at the both ends of the tooth trace directional length H of the tooth profile 3 while other portions remain the same in thickness (D) as illustrated in FIG. 13. The crowing and the relieving will be generically called "crowing etc." hereinafter. Conventional helical gears have prevented the uneven contact between them by forming the aforementioned crowing etc. thereon, thereby preventing the breakage of the tooth profile 3 and reducing the noise caused by the uneven engageme
REFERENCES:
patent: 4954027 (1990-09-01), Faulstich
Kobayashi Youichi
Nishida Noriteru
Nguyen George
Rose Robert A.
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