Abrading – Machine – Rotary tool
Reexamination Certificate
2000-01-19
2001-08-14
Banks, Derris H. (Department: 3723)
Abrading
Machine
Rotary tool
C451S540000
Reexamination Certificate
active
06273801
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to composite honing rings consisting of an abrasive honing part (in the form of a gear tooth ring member) and a peripherally or internally arranged receiving ring, in the following designated as the carrier part, on which the honing part is mounted without any transition element.
BACKGROUND OF THE INVENTION
Honing rings as well as their uses have long been known in the field of gear tooth flank machining. They may be composed of different materials, the abrasive region mostly consisting of synthetic resin-bonded abrasive material, and the carrier rings being made of the same materials. The abrasive part has considerable porosity, which, for some applications, is artificially induced or increased by adding hollow spheres or ceramic agglomerates.
This combinated system corresponds to the effect of conventional grinding wheels, while, on the one hand, vibrations are transmitted to the work piece to be machined, and, on the other hand, the bore play causes inaccuracies which must be corrected for before utilisation, so as to make a stable honing process possible. Irregularities of the abrasive part require reinforcements, for honing rings without reinforcement tend to be subject to uncontrollable tooth breakage, and are thus not secure in their operation.
SUMMARY OF THE INVENTION
The invention aims at avoiding the above drawbacks, which is achieved according to the invention by a composite honing ring of the above kind, characterized in that the abrasive honing ring part has low porosity, in particular a porosity of less than 5%, and preferably contains fibrous reinforcing elements, and in that the carrier part has higher elasticity than the honing part.
This low porosity is achieved, for example, by compressing the honing part composition, e.g. by using hot-pressed epoxy resin. This reduction of porosity results in an increased strength, and it the same time the raggedness after indentation of the abrasive part is drastically reduced, which almost eliminates the tendency of chipping off the work pieces being honed and brings about high dimensional stability of the honing ring.
The fibrous reinforcing elements preferably used in particular have a length of 0,5 to 10 mm. Advantageously, such fibers may be whiskers and do not only reinforce the binder matrix, but in a further advantageous embodiment also participate in the machining of the work piece during honing—thus being abrasive—which results in additional smoothing of the work piece surface and thus an improvement of the surface quality. Whiskers are defined as fibrous single crystals of metals, oxides, borides, carbides, nitrides, polytitanate, carbon, etc., mostly of polygonal cross-section (see Römpp Chemie Lexikon, 9th edition, p. 5039, which is incorporated herein by reference).
The carrier part of the honing ring preferably consists of unfilled synthetic resin, in particular epoxy resin, which is why the materials of the abrasive honing ring part and the carrier part have different damping properties. The carrier part is elastic and causes damping of machine vibrations and bearing oscillations, which are absorbed by the carrier part. Thus the invention is able to achieve optimum honing results even in case of less stable machines and to prevent accumulating process forces.
According to a further preferred embodiment of the invention, the carrier part possesses flow properties under tension. When mounting the inventive part on a machine seat the carrier part encloses it without play, i.e. similar to a press fit. This provides for a very high truth of running, even in case the tools are repeatedly exchanged, as such a press fit is maintained.
In a preferred embodiment the abrasive honing ring part of the composite honing ring according to the invention is filled with abrasive grains, preferably consisting of corundum, SiC, metal nitrides, diamond and CBN grain, in particular having a grain size of ≦200 &mgr;m, which makes efficient and uniform honing possible while at the same time keeping the wear of the honing ring low.
All the above properties taken together result in a good balance between costs and effectiveness, as in this way the honing ring has a much longer service life as compared to conventional honing rings. Service life is additionally prolonged by a reduction of the trueing cycles necessary, as well as by minimum adjustment values in the process of trueing.
Composition of the Honing Ring Members
a) Reinforced honing part with indentation
Components:
Polishing grains, 50-95% by weight, preferably corundum having an average grain diameter of 200 &mgr;m or less; alternatively SiC, diamond, CBN, metal carbides, nitrides and microcrystalline corundum;
binder (resins), 5-50% by weight, preferably epoxy resins;
fillers, 0-15% by weight, inorganic metal salts and/or oxides, organic fillers;
fibrous materials, 1-10% by weight, preferably having a length of 0.5-10 mm, made of glass, ceramics, carbon, plastics (e.g. aramides, amides, polyesters, etc.) and/or whiskers.
b) Carrier part
Components:
epoxide resins comprising different contents of curing agents, ranging from 0.02 to 0.3% by weight.
REFERENCES:
patent: 1924380 (1933-08-01), Rideout
patent: 4707950 (1987-11-01), Kawasaki
patent: 5221294 (1993-06-01), Carman et al.
patent: 1 261 772 (1968-02-01), None
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patent: 0 506 640 (1992-09-01), None
patent: 226533 (1994-08-01), None
patent: 100710 (1995-04-01), None
patent: 214423 (1995-08-01), None
patent: 252768 (1996-10-01), None
J. Falbe, M. Regitz, “Römpp Chemie Lexikon” Georg Thieme Verlag Stuttgart, New York.
Banks Derris H.
Knobbe Martens Olson & Bear LLP
Rappold International Sales
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