METHOD FOR GRINDING METALLIC WORKPIECES CONTAINING, IN PARTICULAR, NICKEL

PROCEDE POUR MEULER DES PIECES METALLIQUES CONTENANT NOTAMMENT DU NICKEL

English Abstract

The invention relates to a method for grinding metallic workpieces containing,
in particular, nickel, whereby a rotationally driven grinding wheel (2) is
continuously dressed by a rotationally driven dressing wheel (3) during the
grinding of the workpiece (1) by the continual advance (vfrd) of the dressing
wheel. In order to increase the grinding capacity, the invention provides that
with a dressing advance velocity of 1 to 2 µm per rotation of the grinding
wheel and with a circumferential velocity of the grinding wheel (vs) of at
least 45 m/s, the advance (table velocity vt) is set such that the rate of
metal removal is at least 90 mm3/mms.

French Abstract

L'invention concerne un procédé permettant de meuler des pièces métalliques contenant notamment du nickel, selon lequel une meule (2) entraînée en rotation, d'une roue de dressage (3) entraînée en rotation est dressée en continu pendant le meulage d'une pièce (1), par approche continue (cfrd) de la roue de dressage. Afin d'augmenter la capacité de meulage, il est prévu d'ajuster l'avance, pour une vitesse d'approche de dressage allant de 1 à 2 µm par rotation de la meule et pour une vitesse périphérique de la meule (vs) d'au moins 45 m/s, de sorte que le taux d'enlèvement de copeaux soit d'au moins 90 mm?3¿/mms.

Claims

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Claims
1. A method for grinding in particular nickel-
containing metallic workpieces, in which a grinding
wheel (2), which is driven in rotation, is continuously
dressed by a dressing wheel (3), which is driven in
rotation, during the grinding of the workpiece (1) by
means of a continuous infeed (vfrd) of the dressing
wheel, characterized in that, at a dressing infeed rate
of 1 to 2 µm per revolution of the grinding wheel and a
circumferential speed of the grinding wheel (vs) of at
least 45 m/s, the advance (table speed vt) is set in
such a way that the material-removal rate is at least
90 mm3/mms.
2. The method according to one or more of the
preceding claims or in particular according thereto,
characterized by a highly porous grinding wheel, in
particular comprising 50% by volume of air.
3. The method according to one or more of the
preceding claims or in particular according thereto,
characterized by a grinding-wheel speed of revolution
of more than 50 m/s, preferably more than 60 m/s, and
an advance which corresponds to a material-removal rate
of more than 100 mm3/mms or more than 150 mm3/mms.

Description

' . CA 02408434 2002-11-07
~ WO 01/89766 PCT/EPO1/04529
Method for grinding in parti~uhar nick~1-containing
metallic v~rorkpieces
The invention relates to a method for grinding in
particular nickel-containing metallic workpieces, in
which a grinding wheel, which is driven in rotation, is
continuously dressed by a dressing wheel, which is
driven in rotation, during the grinding of the
workpiece by means of a continuous infeed of the
dressing wheel.
Methods of this type are known. in the prior art as CD
grinding. The continuous dressing of t.ne grinding wheel
means that the grinding wheel always retains its exact
shape. However, it has the drawback of a high
consumption of the grinding wheel. T~:e grinding
capacity, i.e. the material-removal rate:, is determined
by the table speed. In the prior art, this is set in
such a way that the material-removal rate is below
30 mm3/mms. In the prior art, the infeed rate of the
dressing wheel is less than 1 Ecm/revolution, based on
the grinding wheel. The grinding-wheel speed of
revolution, i.e. the cutting speed, is at most 30 m/s.
The rotation of the dressing wheel is approximately 80$
of the grinding-wheel rotational speed, running in the
same direction as the grinding wheel.
The invention is based on the object of increasing the
grinding capacity.
The object is achieved by the invention specified in
the claims.
In Claim 1 it is provided that the dressing infeed rate
is increased drastically to a level which is between 1
and 2 ~m/revolution. The grinding-wheel speed of
revolution is set to at least 45 m/s. With these
parameters, the advance (table speed) can be set in

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such a way that the material-removal rate is at least
90 mm3/mms. Surprisingly, it has emerged that a
considerable increase in the dressing. infeed rate and
only a relatively moderate increase in the grinding-
s wheel speed of revolution leads to a dispxopo,rtionate
increase in the material-removal rate. Surprisingly, it
has emerged that when the material-removal rate is
increased by increasing the table speed, the normal
forces acting on the table remain virtually constant
and do not rise in the same way. If the grinding wheel
is made from a highly porous material which forms an
air volume of, for example, 50~, it is possible to
improve the results still further. The cutting speed
can be increased to 60 m/s. It is then possible to
achieve material-removal rates of more than l00 mm3/mms,
even for nickel alloys, which form long chips. At a
grinding-wheel speed of revolution of 80 m/s and a
dressing infeed rate of 2 Eun/revolution, it is possible
to achieve material-removal rates of 300 mm3/mms. The
increase in the material-removal rate which is achieved
by increasing the dressing i~n~eed rate is explained by
the fact that the increase in the dressing infeed leads
to an increase in the sharpness of the tool. This is
also deemed responsible for the almost imperceptible
increase in the normal force. Although the method using
the sets of parameters according to the invention leads
to faster wear to the grinding wheel, the consumption
of the grinding wheel is surprisingly compensated for
by the increased material-removal rate, so that overall
the grinding capacity is increased. The penetration
depth of the grinding wheel, which works using its
circumferential surface, is ,pref.erably 3 mm. The table
speed can reach levels of over 1.8 m/_min. The abrasion
to the grinding wheel caused by~.the dressing,, is; greater
than the abrasion during grinding.

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Exemplary embodiments of the invention are explained
with reference to the appended figures, in which:
Fig. 1 diagrammatically depicts the device for
carrying out the method according to the
invention, and
Fig. 2 shows sets of parameters with which optimum
grinding results can be achieved.-
The device for grinding the workpiece 1 comprises a
grinding wheel 2 which is continuously driven in
rotation and is operated at a rotational speed which is
such that it acts on the workpiece 1 with a grinding-
contact speed vs. The direction of rotation is
indicated by the arrow 2'.
The grinding wheel 2 is continuously :dressed by a
dressing wheel 3 which runs in the same. direction 3'
and can be displaced in the direction of the arrow 3" .
The dressing wheel rotates at approximately 80% of the
rotational speed of the grinding wheel. For grinding
purposes, the circumferential surface of the grinding
wheel 2 penetrates a depth ae into the workpiece 1,
which is resting on a moveable table 4 which can be
displaced in the direction indicated by arrow 4' at the
table speed vt.
The grinding wheel consists of a porous material. 25%
of the volume is formed by abrasive grain, 15% by a
binder, while 50% of the volume of the grinding wheel
is air. This is a porous grinding wheel. It is
particularly suitable for nickel alloys.
To enable the considerable horizontal forces which
occur at relatively high material-removal rates to be
absorbed, the grinding wheel may have a specially
reinforced hub (not shown). A grinding' wheel in
accordance with Austrian patent application A 314/2000,

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to which reference is made in its entirety at this
point, is particularly suitable for this purpose.
The parameters illustrated in Fig. 2 are operating
parameters at which the device illustrated in Fig. 1
gives good grinding results. The first set of
parameters corresponds to the prior art. The second set
of parameters shows how a slight increase in the
grinding-contact speed and a drastic 'increase in the
dressing infeed rate vfrd leads to an initially
approximately proportional increase in the material-
removal rate.
A further increase in the contact speed vs to 45 m/s,
while only involving approximately doubling the
grinding-contact speed, leads to a material-removal
rate which is more than four times greater than that
achieved with the set of parameters used in the prior
art.
At a contact speed of 50 m/s, with a dressing infeed
rate of 1.5 ~m/revolution it is even possible to
achieve a material-removal rate of 150 mm3/mms. If the
contact speed is increased to 80 m/s, with a dressing
infeed rate of 2 Etm/revolution it is even possible to
achieve a material-removal rate of 300 mm3/mms.
The sets of parameters illustrated in Fig. 2 were
determined by carrying out grinding experiments in
which the cutting speed vs and the infeed rate vfrd of
the dressing wheel were kept constant and the advance
(table speed) vt was increased in steps. The value
shown in Fig. 2 for the material-removal rate
corresponds to the experiment with the highest advance
in which a sufficiently good grinding result was still
achieved.

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All features of the invention disclosed are
(inherently) pertinent to the invention. The disclosure
content of the associated/appended priority documents
(copy of the prior application) and of A 314/2000 is
hereby incorporated in its entirety in the disclosure
of the present application, partly with a view to
incorporating features of these documents in claims of
the present application.

Representative Drawing