Abrading – Abrading process – Gear or worm abrading
Patent
1994-09-20
1997-04-29
Rose, Robert A.
Abrading
Abrading process
Gear or worm abrading
451 21, 451219, B24B 100
Patent
active
056243014
DESCRIPTION:
BRIEF SUMMARY
This invention covers a method and mechanism for the grinding of groove-shaped external profiles on work pieces, particularly for the grinding of the teeth of straight and helical spur gears, i.e., profile sections of one and the same work piece are simultaneously machined by two grinding wheels which are profiled according to the required external profile contours of the work pieces and the metal is removed by opposite feed movement and joint stroking travel of the two grinding wheels.
It is known that with profile grinding the accuracy of the profile generated on the work piece depends principally on the accuracy of the grinding wheel profile. This is due to the fact that the profile of the grinding wheel is directly transferred to the work piece. Each deviation from the desired profile of the grinding wheel results in a real error on the work piece.
Consequently, the grinding wheel has to have the precise negative profile of the profile to be produced in order to obtain a high machined accuracy.
On the other hand, the topography of the grinding wheel is determined by the mode and method used to profile the grinding wheel. The topography, in turn, influences to a large extent the accuracy and efficiency of the grinding operation.
Due to the afore said causes, the process of profiling the grinding wheel is most important with profile grinding.
Various methods and mechanisms are known for the profile grinding of work pieces which also include solutions for the dressing of grinding wheels.
According to Keck "Die Zahnradpraxis" (Published by R. Oldenbourg, Munich, 1956), pages 195 and following, the use of two grinding wheels for the simultaneous machining of opposite tooth flanks of one and the same gear wheel with profile grinding is known. Both grinding wheels are firmly and co-axially mounted on a single grinding spindle, a defined distance apart. Before the grinding process starts the grinding wheels are profiled by a dresser.
This solution has the disadvantage that the two grinding wheels exhibit a low stiffness because of their disc shape. The low stiffness of the grinding wheels and their different inclination caused by the spindle bending lead to reduced machining accuracy. This disadvantage occurs especially when gear wheels featuring a small module are machined. In connection with this solution ways of profile dressing the grinding wheels is described. This description refers to the method by which the profiled grinding wheels are diamond dressed, whose points follow a given path which is controlled by templates. This, in turn, makes it necessary to produce a special template for each profile.
A further disadvantage of this solution is poor flexibility, since the machine can only be changed to other machining tasks by the necessary alteration to the grinding wheel mounts, changing the grinding wheels and resetting the dresser. A process which is both time consuming and costly.
In the DD-AP 291 500 a solution is described which covers the machining of profiled work pieces, particularly gear wheels, by two separately arranged grinding wheels. Each grinding wheel is located on a grinding slide and both grinding slides are inclined by a fixed angle related to the traversing axes of the grinding slides. For the profiling, a separate dressing tool is allocated to each grinding wheel. The grinding wheels are profiled through continuous path control along the machine axes Y.sub.A /U.sub.1 and Y.sub.A /U.sub.2. The disadvantage of this solution is that the infeed travel of the dressing slide .DELTA. Y.sub.A requires a compensation for the two grinding wheel axes by .DELTA.U.sub.1 and .DELTA.U.sub.2. In this, both the positioning errors of the dressing tools and the compensatory movement directly effect the machining accuracy.
A further disadvantage is that, in order to guide the machine axes Y.sub.A /U.sub.1 and Y.sub.A /U.sub.2 along a continuous path, the work piece profile has to be permanently transferred into the software controlling the dressing profile, which increases the cost of the computer requi
REFERENCES:
patent: 3776213 (1973-12-01), Clarke et al.
patent: 4393625 (1983-07-01), Bloch et al.
patent: 4400916 (1983-08-01), Bloch et al.
Werkstatt und Betrieb vol. 118, No. 5, May 1985, Munchen (DE) pp. 289-293.
H.H. Hofmann 'Zahnflankenschileifen Mit Life See p. 292, right-hand col., line 12-p. 293, left hand col. line 11: Fig. 8.
Keck "Die Zahnradpraxis" Verlag R. Oldenbourg Munchen(DE)1956 see pp. 195 ff. cited in the application.
Lenz Sieghart
Ruhle Jurgen
Ulrich Hans-Joachim
NILES Werkzeugmaschinen GmbH Berlin
Rose Robert A.
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