TETE D'OUTIL S'UTILISANT DANS DES MACHINES-OUTILS

TOOL HEAD FOR USE IN MACHINE TOOLS

Abrégé français

L'invention concerne une tête d'outil s'utilisant dans des machines-outils. Cette tête d'outil comprend principalement un corps de base (10), une tige d'outil (16) pouvant être accouplée à un arbre de machine et faisant saillie au-dessus du corps de base dans le sens axial, une cavité (18) pour loger un outil de coupe (20) et une coulisse rotative (30) qui porte de manière excentrée la cavité (18) pour loger l'outil de coupe (20) et peut tourner par rapport au corps de base (10), avec déplacement du rayon de coupe de l'outil de coupe (20), autour d'un axe à excentrique (28) parallèle à l'axe du corps de base (12). Afin de garantir une géométrie de coupe constante pendant le processus de coupe, la cavité (18) qui loge l'outil de coupe peut être ajustée de manière définie en fonction de l'angle d'ajustement de la coulisse rotative (30) ou en fonction du rayon de coupe, par rapport à la coulisse rotative (30).

Abrégé anglais

The invention concerns a tool head for use in machine tools. The tool head
substantially comprises a basic body (10), a tool shank (16) which projects
axially over the basic body (10) and can be coupled to a machine spindle, a
tool holder (18) for a cutting tool (20) and a rotary slide (30) which
supports the tool holder (18) eccentrically and can be rotated relative to the
basic body (10), with adjustment of the cutting radius of the cutting tool
(20), about an eccentric axis (28) parallel with the basic body axis (12). In
order to ensure that the cutting geometry is constant during a cutting
operation, the tool holder (18) can be adjusted in defined manner relative to
the rotary slide (30) as a function of the adjusting angle thereof or of the
cutting radius.

Revendications

15
claims
1. A tool head for use in machine tools, comprising a base
body (10), a tool shank (16) which is disposed on the
base body (10) and which is adapted to be coupled to a
rotating machine spindle (14), a tool holding fixture
(18) for a cutting tool (20), and a rotary slide (30)
which eccentrically carries the tool holding fixture
(18) and which is rotatable with respect to the base
body (10), preferably about an eccentric axis (28)
parallel to the base body axis (12), thereby adjusting
the cutting radius of the cutting tool (20),
characterized in that the tool holding fixture (18) is
adapted to be adjusted in a defined manner with respect
to the rotary slide (30) dependent on the rotary angle
(.alpha.) of the rotary slide (30) or on the cutting radius
(s, x).
2. The tool head of claim 1, characterized in that the
tool holding fixture (18) is adapted to be adjusted
with respect to the rotary slide (30) aligning the
cutting tool (20) relative to the base body axis (12)
in a defined manner.
3. The tool head of claim 1 or 2, characterized in that
the tool holding fixture (18) is adjustable with
respect to the rotary slide (30) with the base body
axis (12) under alignment of a reference plane (60)
associated with the cutting tool (20).
4. The tool head of one of claims 1 to 3, characterized in
that the tool holding fixture (18) is disposed in an
eccentric bore (22) of the rotary slide (30) such that

16
it is rotatable about an axis which is parallel to the
eccentric axis (28) of the rotary slide.
5. The tool head of one of claims 1 to 4, characterized by
an alignment rail (72) which protrudes over the base
body axis (12) and which is rotatable about this axis,
with respect to which alignment rail a reference plane
(60) which is associated with the tool holding fixture
(18) or the cutting tool (20) is adapted to be aligned
during the adjustment of the rotary slide (30).
6. The tool head of one of claims 1 to 5, characterized in
that the rotary slide (30) and the tool holding fixture
(18) are coupled to each other and to the base body by
transmission means (50, 52, 54, 58; 62 64, 66, 68, 70;
72, 74, 60).
7. The tool head of claim 6, characterized in that the
transmission means comprise gears, toothed rings and/or
toothed racks.
8. The tool head of claim 6 or 7, characterized in that
the transmission means are adapted to be actuated
without free play.
9. The tool head of one of claims 6 to 8, characterized in
that the transmission means comprise on the drive side
a rotary reducing gear unit (47) or a translation-to-
rotation conversion gear unit (47').
10. The tool head of claim 9, characterized in that the
rotary reducing gear unit (47) is designed to be a
planetary gear unit or a harmonic drive gear unit

17
having drive and driven axes (45, 48) which are coaxial
with respect to each other.
11. The tool head of claim 9 or 10, characterized in that
the reducing gear unit (47) or the conversion gear unit
(47') and the transmission means coupled thereto are
disposed within the base body, preferably in a radially
interpenatrating manner.
12. The tool head of one of claims 1 to 11, characterized
in that for the cutting radius of the tool head in
dependency of the angle (.alpha.) of rotation of the rotary
slide (30) about its eccentric axis (28) the relation
<IMG>
and for the correction angle .delta.'(.alpha.) of the reference
plane (60) of the cutting tool (20) the relation
<IMG>
are valid, wherein r denotes the cutting radius with
respect to the eccentric axis of the rotary slide
(eccentricity) and a denotes the smallest cutting ratio
with respect to the base body axis (12).
13. The tool head of one of claims 1 to 12, characterized
in that for the cutting edge intersecting the base body
axis (12) in a starting position (a = 0) the relation
<IMG>

18
is valid for the cutting radius s in dependency of the
angle of rotation .alpha. of the rotary slide (30) and
.delta. = .alpha./2
is valid for the correction angle, wherein r denotes
the eccentricity of the rotary slide (30).
14. The tool head of one of claims 1 to 13, characterized
in that the rotary slide (30) is rotatably borne in an
eccentric bore (32) of the base body (10), that the
tool holding fixture (18) is rotatably borne in an
eccentric bore (22) of the rotary slide (30), that
transmission means (50, 52) on the side of the rotary
slide are disposed between a base-body-fixed or
machine-side drive mechanism (rotary rod, driven shaft
48) and the rotary slide (30), that transmission means
(54, 56, 58) on the side of the tool holding fixture
are disposed between the tool holding fixture (18) and
the base body (10), and that the transmission means on
the side of the rotary slide and the transmission means
on the side of the tool holding fixture have a defined
transmission ratio.
15. The tool head of claim 14, characterized in that the
transmission means on the side of the rotary slide
comprise a toothed ring which is adapted to be driven
by the drive mechanism (rotary rod, driven shaft 48),
which is concentric with respect to the base body axis
(12), and which is preferably designed to be an
internally toothed ring (50), and comprising a toothed
ring meshing with the former, which is preferably
designed to be a rotary-slide-fixed externally toothed
ring (52).

19
16. The tool head of claim 14 or 15, characterized in that
the transmission means on the side of the tool holding
fixture comprise a base-body-fixed gear (58) and a
tool-holding-fixture-fixed toothed ring meshing
therewith and preferably being formed to be an
internally toothed ring (54).
17. The tool head of one of claims 1 to 16, characterized
in that at least part of the toothed rings and the
associated parts are formed segment-like (Fig. 1c).
18. The tool head of one of claims 1 to 13, characterized
in that a round slide (34) is rotatably borne in a
concentric bore (40) of the base body (10), that the
rotary slide (30) is rotatably borne in an eccentric
bore (32) of the round slide (34), that the tool
holding fixture (18) is rotatably borne in an eccentric
bore (22) of the rotary slide (30), that the round
slide (34) is rotatable, taking along the rotary slide
(30) and the tool holding fixture (18), about the base
body axis (12) by means of a base-body-fixed or
machine-side drive mechanism (rotary rod, driven shaft
48), that transmission means (62, 69, 66, 68, 70) are
disposed between the base body (10) on the one hand and
the rotary slide (30) and the tool holding fixture (18)
on the other hand, which transmission means are matched
to each other by way of a defined transmission ratio.
19. The tool head of claim 18, characterized in that the
rotary slide (30) carries a toothed ring (62) which is
concentric with respect to it axis of rotation (28),
with which it rolls off on a base-body-fixed toothed

20
ring which is preferably formed to by an internally
toothed ring (64).
20. The tool head of claim 18 or 19, characterized in that
the tool holding fixture (18) carries a toothed ring
(66) which is concentric with respect to its axis of
rotation, with which it rolls off on a base-body-fixed
toothed ring which is preferably formed to be an
internally toothed ring (70), if need be over an
interposed intermediate gear (68) loosely borne on the
rotary slide (30).
21. The tool head of one of claims 14 to 20, characterized
in that the drive mechanism comprises a rotary rod
which is coaxial with respect to the base body axis
(12) and which is driven from the machine side.
22. The tool head of one of claims 14 to 21, characterized
in that the drive mechanism comprises an intermediate
transmission having a driven shaft (48) which is
concentric with respect to the base body axis (12).
23. The tool head of one of claims 18 to 22, characterized
in that the eccentricities of the eccentric bores (32,
22) in the round slide (34) and the rotary slide (30)
are of equal magnitude.
24. The tool head of one of claims 1 to 23, characterized
by an angle or displacement measuring system (80, 82)
measuring the adjusting angle of the rotary slide (30)
or of the round slide (34) or the displacement of the
cutting tool (20).

21
25. The tool head of one of claims 1 to 29, characterized
by balancing weights (49, 46) disposed in the rotary
slide (30) and/or the base body (10) and/or the round
slide (34) for balancing the tool head with respect to
the base body axis (12).
26. The tool head of one of claims 1 to 25, characterized
in that separate drive means which can be
electronically coupled to each other are provided for
the rotary slide (30) and the tool holding fixture
(18).
27. The tool head of one of claims 1 to 26, characterized
in that at least two rotary slides having adjustable
tool holding fixtures are provided, which are disposed
in eccentric bores of the base body or of the round
slide and which can be driven in unision or seperately.

Description

CA 02277961 1999-07-20
' 1
n~
Tool head for use in machine tools
Description
The invention relates to a tool head for use in machine
tools, comprising a base body, a tool shank which is
disposed on the base body and which is adapted to be
coupled to a rotating machine spindle, a tool holding
fixture for a cutting tool, and a rotary slide which
eccentrically carries the tool holding fixture and which is
rotatable with respect to the base body, preferably about
an eccentric axis parallel to the base body axis, thereby
adjusting the cutting radius of the cutting tool.
In DE-A-196 17 877 it has been proposed for an application
with a plane turning lathe head to provide as a working
slide a rotary slide which is eccentrically disposed on the
tool head, which rotary slide is rotatable by means of a
drive sprocket and a gear rigidly connected to the rotary
slide, thereby essentially radially adjusting the tool
holding fixture. The rotation of the rotary slide results
in no mass displacement, so that the provision of a
compensating slide is not necessary. A disadvantage of this
rotary slide, though, is that not only the distance of the
cutting edges with respect to the base body axis is changed
during an adjustment, but that also the alignment of the
cutting edge with respect to the axis of rotation is
changed.
Based on this it is the object of the invention to improve
the known tool head of the type described above such that
the cutting edge geometry can adapt during an adjusting
process.

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2
For the solution of this object the combination of features
stated in patent claim 1 is proposed. Advantageous
embodiments and further developments of the invention
result from the dependent claims.
The solution according to the invention is based foremost
on the idea that the tool holding fixture is adapted to be
adjusted in a defined manner with respect to the rotary
slide dependent on the rotary angle of the rotary slide or
on the cutting radius. By this it is possible to hold
constant the cutting edge geometry during an adjustment of
the cutting radius. This can, for instance, be effected by
the tool holding fixture being adapted to be adjusted with
respect to the rotary slide aligning the cutting tool
relative to the base body axis in a defined manner. This is
expediently realized by the tool holding fixture being
adjustable with respect to the rotary slide with the base
body axis under alignment of a reference plane associated
with the cutting tool. To this end the tool holding fixture
can be disposed in an eccentric bore of the rotary slide
such that it is rotatable about an axis which is parallel
to the eccentric axis of the rotary slide.
According to a preferred embodiment of the invention there
is provided an alignment rail which protrudes over the base
body axis and which is rotatable about this axis, with
respect to which alignment rail a reference plane which is
associated with the tool holding fixture or the cutting
tool is adapted to be aligned during the adjustment of the
rotary slide.
According to an alternative embodiment of the invention the
rotary slide and the tool holding fixture are coupled to

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3
each other and to the base body by transmission means,
wherein the transmission means are expediently formed.to.be
a gear transmission.
According to a preferred further development of this
principle the rotary slide is rotatably borne in an
eccentric bore of the base body, while the tool holding
fixture is rotatably borne in an eccentric bore of the
rotary slide. Transmission means on the side of the rotary
slide are disposed between a base-body-fixed or machine-
side drive mechanism and the rotary slide, while
transmission means on the side of the tool holding fixture
are disposed between the tool holding fixture and the base
body. In this, the adjustment of the cutting edge is
effected by the transmission means on the side of the
rotary slide and the transmission means on the side of the
tool holding fixture having a defined transmission ratio.
The transmission means on the side of the rotary slide
expediently comprise a toothed ring which is adapted to be
driven by the drive mechanism, which is concentric with
respect to the base body axis, and which is preferably
designed to be an internally toothed ring, and comprising a
toothed ring meshing with the former, which is preferably
designed to be a rotary-slide-fixed externally toothed
ring, while the transmission means on the side of the tool
holding fixture comprise a base-body-fixed gear and a tool-
holding-fixture-fixed toothed ring meshing therewith and
preferably being formed to be an internally toothed ring.
In order to be able to transfer the forces occurring during
the cutting and adjusting processes without free play, the
rotary slide is borne in an axial/radial bearing which is
disposed in the eccentric bore and which is preferably
formed to be a tapered roller bearing. Due to the limited

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4
available space at least part of the toothed,rings and the
associated parts are formed segment-like, wherein it must,
be taken into consideration that in these regions there are
no full rotations but only partial rotations of the parts.
Due to the eccentric arrangement of the cutting tool on the
rotary slide an imbalance results, which can be compensated
by providing balancing weights in the rotary slide as well
as in the base body. A considerable advantage of the rotary
slides is that the imbalances can be designed to be
symmetrical. This means that they are mass-symmetrical with
respect to their respective axis of rotation. Therefore, a
precise balancing of the tool head with respect to its axis
of rotation is possible, without the need for providing a
compensation slide.
According to a further embodiment of the invention a round
slide is rotatably borne in a concentric bore of the base
body, the rotary slide is rotatably borne in an eccentric
bore of the round slide, the tool holding fixture is
rotatably borne in an eccentric bore of the rotary slide,
wherein the round slide is rotatable, taking along the
rotary slide and the tool holding fixture, about the base
body axis by means of a base-body-fixed or machine-side
drive mechanism, and wherein transmission means are
disposed between the base body on the one hand and the
rotary slide and the tool holding fixture on the other
hand, which transmission means are matched to each other by
way of a defined transmission ratio. The rotary slide
carries as transmission means a toothed ring which is
concentric with respect to it axis of rotation, with which
it rolls off on a base-body-fixed toothed ring which is
preferably formed to by an internally toothed ring. On the
other hand, the tool holding fixture expediently carries a

CA 02277961 1999-07-20
- toothed ring which is concentric with respect to its axis
of rotation, with which it rolls off on a base-body-fixed
toothed ring which is preferably formed to be an internally
toothed ring, if need be over an interposed intermediate
5 gear loosely borne on the rotary slide. The eccentricities
of the eccentric bores in the round slide and the rotary
slide advantageously are of equal magnitude.
The drive mechanism advantageously comprises a rotary rod
which is coaxial with respect to the base body axis and
which is driven from the machine side or an intermediate
transmission having a driven shaft which is concentric with
respect to the base body axis. The intermediate
transmission may therein be designed to be a rotary
reducing gear unit or a translation-to-rotation conversion
gear unit. Advantageously, the rotary reducing gear unit is
designed to be a planetary gear unit or a harmonic drive
gear unit having drive and driven axes which are coaxial
with respect to each other.
In principle it is possible to provide separate drive means
which can be electronically coupled to each other for the
rotary slide, the round slide and the tool holding fixture.
This makes it possible to fashion the adjustment rules for
the tool holding fixtures in dependency on the rotary slide
adjustment to be largely arbitrary. In this way the chip
forming can be influenced, for instance when machining work
pieces consisting of different materials. Moreover, the
service life of the cutting edges can be extended in this
manner.
For monitoring the adjustment path a preferably electronic
angle or displacement measuring system measuring the
adjusting angle of the rotary slide or of the round slide

CA 02277961 1999-07-20
6
- or the displacement of the cutting tool can be provided in
the base body.
According to a further advantageous embodiment of the
invention at least two rotary slides having adjustable tool
holding fixtures are provided, which are disposed in
eccentric bores of the base body or of the round slide and
which can be driven in unision or seperately.
In the following the invention will be further described
with reference to embodiment schematically shown in the
drawing, in which:
Fig. la shows a section through a tool head designed to
be a plane turning lathe head having an eccentric
rotary slide;
Fig. lb shows a plan view of the tool head with the tool
holding fixture;
Fig. lc shows a section through the tool head in the
region of the gear transmission;
Fig. ld shows a section through the rotary slide;
Fig. 2a and b schematically show a plan view of the tool
head in two rotary positions of the rotary slide;
Fig. 3a shows a plan view of an embodiment of a plane
turning lathe head which is modified with respect
to Fig. l;
Fig. 3b shows a section along the line B-B in Fig. 3a;

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7
Fig. 3c shows a section through the tool head rotated b.y
90° with respect to Fig. 3b;
Fig. 3d shows a section along the line D-D in Fig. 3a;
Fig. 4a shows a section through a tool head modified with
respect to Fig. 1 and 3 and having a concentric
round slide and an eccentric rotary slide;
Fig. 4b and c schematically show a plan view of the tool
head according to Fig. 4a in.two different
angular positions of the round slide;
Fig. 5 shows a schematic plan view of a modified tool
head comprising an alingment rail;
Fig. 6a shows a diagram for calculating the cutting
radius and the correction angle of a tool head
having a rotary slide in a simplified
representation;
Fig. 6b and c show two diagrams s = s(a) and b = 8(a);
Fig. 7 shows a model for calculating the cutting radius
(x) and the correction angle (8) of the cutting
insert for a tool head with an arrangement of the
rotary slide in the base body, which has been
generalized with respect to Fig. 6a.
The tool heads shown in the drawing are intended to be used
as plane turning lathe heads in machine tools. The tool
heads essentially consists of a base body 10 which is

CA 02277961 1999-07-20
8
rotatable about an axis of rotation 12, a tool shaft 16
which axially protrudes over the base body and can be.
coupled to a mchine spindle 14 (Fig. 4a), a toll holding
fixture 18 for a cutting tool 20, a cutting insert 26 which
has a cutting edge 24 and which is disposed on the cutting
tool 20, and a rotary slide 30 which carries the tool
holding fixture 18 in an eccentric bore 22 and which is
rotatable with respect to the base body 10 about an
eccentric axis 28 parallel to the base body axis 12,
thereby adjusting the cutting radius of the cutting edge
24. To this end, the rotary slide 30 is borne in an
eccentric bore 32 of the base body 10 (Fig. 1 and 3) or of
a round slide 34 (Fig. 4) by means of roller bearings 36.
In the case of Fig. 4 the round slide 34 is in turn borne
in roller bearings 38 in a bore 40 which is concentric with
respect to the axis of rotation 12. The tool holder fixture
18 is, in the case of Fig. 1 and 3, borne with its
cylindrical surface in a plain bearing which forms the
eccentric bore 22, while in the case of Fig. 4 it is
additionally supported in the eccentric bore 22 by a roller
bearing 42.
As can be seen especially from Fig. la, 3c and d as well as
Fig. 4b, the eccentric bores 22, 32 have in the embodiments
shown the same eccentricity e. An imbalance is created by
the eccentric arrangement of the cutting tool 20 in the
rotatary slide 30 on the one hand and by the eccentric
arrangement of the rotary slide 30 in the base body 10 or
in the round slide 34 on the other hand, which imbalance
can be balanced by balancing weights 44 in the rotary slide
30 and balancing weights 46 in the base body 10 or in the
round slide.

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9
A substantial advantage of the rotary slide is that
imbalances with respect to the axis of rotation 12 of,the~
base body can be balanced mass-symmetrically. The rotation
of the rotary slide does not result in a mass shift, so
that a compensating slide is not needed. Therefore only a
relatively small drive power which is independent of the
adjusting path is needed.
In the embodiments shown in Fig. 1 to 3 the rotary slide 30
is driven by a a machine-side drive mechanism having a
rotary rod or driven shaft 48 which is concentric with
respect to the axis of rotation 12. The drive mechanism
comprises a conversion transmission to slow speeds, the
machine-side drive shaft 47 of which and the head-side
driven shaft 48 of which are disposed coaxially with
respect to each other. The transmission ratio of the
conversion transmission is expediently chosen to lie
between 10:1 and 1000:1, preferably about 100:1.
The driven shaft 48 carries at its face end a segment-like
internally toothed ring 50 which meshes with an externally
toothed ring 52 of smaller diameter on the rotary slide 30
and which has no free play with respect thereto. When
rotating the rotary slide 30 the tool holding fixture 18 is
carried along, thereby adjusting the cutting radius of the
cutting edge 24. In order to compensate the cutting
geometry (alignment of the cutting edge with respect to the
axis of rotation 12) during the adjustment of the cutting
tool, the tool holding fixture 18 carries an internally
toothed ring 54 which is concentric with respect to the
axis of the tool holding fixture 18, which ring meshes with
a base-body-fixed gear 58 which can be formed onto a base-
body-fixed holder 11. The transmission ratios of the
transmission means formed by the internally toothed ring 50

CA 02277961 1999-07-20
and the externally toothed ring 52 on the one hand and the
transmission means formed by internally toothed ring 54 and
the gear 58 on the other hand are matched to each other
such that the cutting insert 26 is aligned relative to the
5 axis of rotation 12 with its reference plane 60 in each
rotary position of the rotary slide 30. In the embodiment
shown in Fig. 2a and b the cutting insert 26 is adjusted by
a correction angle S = 15° for an angle of rotation a = 30°
of the rotary slide 30. At the same time the cutting
10 diameter is increased from initially 50 mm to 54.14 mm.
In the embodiment according to Fig. 4a to c the round slide
34 is rotated concentrically with respect to the base body
10 by means of the rotary rod or driven shaft 48. The
driven shaft 48 in turn is driven by a drive mechanism
which comprises a machine-side pull rod 51 and a
translation-to-rotation conversion transmission 47'. The
displacement effected by the pull rod 51 in the direction
of the double arrow 49 is converted into the desired
rotation of the driven shaft 48 in the direction of the
arrow 53 by means of the conversion transmission 47'. The
drive mechanism and the transmission means can be arranged
in an interpenetrating manner within the base body 10 such
that a relatively short length results. The rotary slide 30
which is disposed in the eccentric bore 32 of the round
slide as well as the tool holding fixture which is disposed
in the eccentric bore 22 are carried along in the direction
of rotation by the driven shaft 48. The rotary slide 30
carries an externally toothed ring 62 for the adjustment of
the rotary slide 30 with respect to the round slide 34 and
the base body 10, which ring 62 meshes with a base-body-
fixed internally toothed ring 64. Furthermore, the tool
holding fixture 18 carries an externally toothed ring 66

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11
which is concentric with respect to the axis. thereof, which
ring 66 meshes with a base-body-fixed internally toothed.
ring 70 by way of an intermediate gear 68 which is loosely
positioned on the rotary slide axis 28. The transmission
ratios of the transmission means formed by the described
toothed rings are matched to each other such that upon
adjusting the cutting radius of the cutting insert 26 the
reference plane 60 associated with the cutting insert 26 is
aligned with respect to the axis of rotation 12 (cf. the
transition between Fig. 9b and c).
In the embodiment of a tool head schematically shown in
plan view in Fig. 5 the rotary slide 30 which is borne
rotatably about the eccentric axis 28 in the base body 10
is also fitted with a tool holding fixture 18 which is
rotatably positioned in an eccentric bore 22 of the rotary
slide. The alignment of the reference. plane 60 of the
cutting insert 26 with respect to the axis of rotation 12
of the tool head is in this instance performed by means of
an alignment rail 72 which is rotatable on the base body 10
about the axis of rotation 12 and which lies against the
reference plane 60 of the cutting insert 26 with its
alignment surface 74 and which rotatably carries along the
tool holding fixture 18 in its eccentric bore 22 during the
adjusting process. The alignment rail 72 therefore fulfills
the same function as the gear transmissions according to
Fig. 1 to 4.
In the embodiment shown in Fig. 6a there is provided a
displacement path measuring system which comprises a rule
80 which is connected to the cutting insert carrier and a
measuring head 82 which is disposed on the alignment rail
72. With these means an absolute measurement of the

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12
adjusting path of the cutting insert 24 with.respect to the
base body 10 is possible. , ,
In the diagram of Fig. 6a the displacement and angle
relationships are shown for the simplified case of the
adjusting path of the cutting insert 24 running through the
axis of rotation 12 from the sarting point, from which
relationships the following formula for the cutting radius
s(a) and for the correction angle of the cutting edge 8(a)
can be derived.
The cutting radius with respect to the base body axis 12 in
dependency of the angle a of the rotary slide in this case
is
s(a) = r 2(1- cosa) (1 )
wherein r denotes the cutting radius with respect to the
eccentric axis 28 and therefore the eccentricity of the
rotary slide 30.
For the correction angle 8 being a function of the angle of
rotation a the following relationship results
8 = a/2 ~ (2~.
The relationships according to the equations (1) and (2)
are shown in the graphs of Fig. 6b and c.
The diagram of Fig. 7 shows the paths and angles which are
necessary for calculating the cutting radius x and the
correction angle 8' for the general case of the rotary
slide eccenter being disposed out of center.

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From this the equation for the cutting radius x as a
function of the angle of rotation a of the rotary slide
follows as
x(a)=Ja2+2r2(1-casa)+4arsina(a/2) (3)
wherein r denotes the radius of the cutting insert 26 with
respect to the eccentric axis 28 of the rotary slide 30,
and a denotes the smallest cutting radius with respect to
the axis of rotation 12. For the correction angle 8' in
denpendency of the angle of rotation a the equation
a 1 + cosa (4)
8 ~ (a) = a / 2 + 90°- arcsin
~x(a)
follows, wherein x(a) is to be substituted from equation
(3) .
The definition of the correction angle 8' differs from the
definition of the correction angle 8 of equation (2) by an
angle of 90°.
The angles (3, y, and s and the path s additionally shown in
the diagram of Fig. 7 are needed for the derivation of
equations ( 3 ) and ( 9 ) .
In summary the following is to be stated: The invention
relates to a tool head for use in machine tools. The tool
head essentially consists of base body 10, a tool shank 16
which is disposed on the base body 10 and which is adapted
to be coupled to a rotating machine spindle 14, a tool
holding fixture 18 for a cutting tool 20, and a rotary

CA 02277961 1999-07-20
14
slide 30 which eccentrically carries the tool holding
fixture 18 and which is rotatable with respect to th~,ba5e
body 10, preferably about an eccentric axis 28 parallel to
the base body axis 12, thereby adjusting the cutting radius
of the cutting tool 20. In order to ensure a constant
cutting geometry during a cutting process the tool holding
fixture 18 is adapted to be adjusted in a defined manner
with respect to the rotary slide 30 dependent on the rotary
angle of the rotary slide 30 or on the cutting radius.

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