Note: Descriptions are shown in the official language in which they were submitted.
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Method for machining a workpiece as well as such machining device
DESCRIPTION
The invention relates to a method for machining a workpiece, wherein the
workpiece is fixed in a first gripping device of a machining device, in order
to make at
least one element, after which the workpiece is transferred to a second
gripping
device of the machining device, where by means of the element the workpiece is
fixed
in the second gripping device of the machining device, while the first
gripping device
remains connected to the machining device.
The invention also relates to a machining device for machining a workpiece,
which machining device is provided with at least a first gripping device that
is suited
for fixing the workpiece to be provided with an element, which machining
device is
further provided with a second gripping device that is suited for fixing the
workpiece
by means of the element.
In such method, known from US-Patent 5. 582. 297, the workpiece is machined
while being fixed in the first gripping device. Next it is fixed with the
machined
portion in a second gripping device, after which further machining takes
place. In this
known method only a limited number of operations is possible on the workpiece
in
the second gripping device, because of the manner of clamping.
The invention aims at providing a method wherein in a workpiece can simply be
provided with a mounting element, with which it can be firmly and accurately
fixed,
after which nearly the entire workpiece can be machined.
This object is achieved with the device according to the invention in that the
first and second gripping devices are located on different sides of a gripping
table that
is swivelling about a swivel axle, which swivel table is at least swivelling
from a first
position, in which the workpiece that is fixed in the first gripping device
can be
machined for making in the workpiece the element that comprises a dovetail-
shaped
mounting element, towards a second position in which the workpiece that is
fixed in
the second gripping device by means of the dovetail-shaped mounting element
can be
machined, and vice versa.
By swivelling the gripping table the first or the second gripping device can
easily
be put in a position where the workpiece fixed in the relevant gripping device
can be
machined. Such machining may e. g. be a metal-removing operation, like
cutting,
drilling etc.
In this way it is possible with one and the same machining device to make the
dovetail-shaped mounting element in the workpiece, as well as to carry out
further
operations to the workpiece.
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The first gripping device is suited for holding the workpiece is such a way
that
the dovetail-shaped mounting element can be made in the workpiece. During this
procedure the workpiece can be fixed along nearly its complete circumference,
if
desired. The workpiece provided with the dovetail-shaped mounting element can
consequently be positioned in the second gripping device, and be further
machined.
Interim storage of the workpieces provided with the dovetail-shaped mounting
element is not necessary in the method according to the invention. The
advantage of
fixing the workpiece with a dovetail-shaped mounting element is that the
dovetail-
shaped mounting element is just located on only one side of the workpiece, so
that
the remaining sides are easily accessible and can thus be machined. Moreover a
good
fixation is achieved by means of a dovetail-shaped mounting element.
Because of the dovetail-shaped mounting element a very stable and accurately
positioned attachment is achieved. Herewith only a minimal amount of material
needs to be removed, so that the machining time is short and a relatively
small base
material may be chosen, especially as regards cylindrical material. The
entirety of the
gripping devices with the dovetail-shaped mounting element facilitate an
efficient
and reliable automated machining process, which can be carried out unmanned on
e.
g. a 5-axled machine tool. An instance of such per se known 5-axled machine
tool is a
5-axled cutting tool.
As the first and second gripping devices are located on different sides of a
gripping table that is swivelling about a swivel axle, each gripping device
can be easily
positioned with respect to the machining tool.
It should be noted that in the method known from the US-Patent 5. 582. 297 a
component to be formed in the workpiece is used as a mounting element.
Therefore
no optimal fixation is guaranteed. As moreover in the arrangement according to
the
US-Patent 5. 582. 297 the gripping devices are positioned stationary, the one
gripping
device may obstruct the machining of the workpiece that is fixed in the other
gripping
device. Since in the method according to the invention the gripping devices
are
located on a gripping table that is swivelling about a swivel axle, it is
possible to direct
the workpiece clamped with the dovetail-shaped mounting element towards the
tool,
while the first gripping device does not obstruct the machining of the
workpiece by
means of the tool.
Furthermore it should be noted that usually with a separate device mounting
elements are made in a number of workpieces, after which the workpieces are
stored.
As soon as one wishes to machine the workpiece further, the workpiece needs to
be
collected from storage, after which it can simply be mounted in the machining
device
by means of the mounting element. As long as the workpiece is not provided
with a
mounting element, the workpiece cannot be fixed onto the known machining
device,
unless the gripping device is replaced. Replacement of gripping devices is
time-
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consuming and undesirable, certainly in the case of automated machining
devices. An
employee is required for replacing gripping devices. The subsequent making of
the
dovetail-shaped mounting element takes a relatively short time, which means
that in
the meantime the employee can do nothing else but wait until the gripping
device
needs replacing again.
By means of the method according to the invention the dovetail-shaped
mounting element can be made in the workpiece fully automatically in the
machining
device, the workpiece provided with the dovetail-shaped mounting element can
be
fixed by means of the dovetail-shaped mounting element and can subsequently be
machined.
An embodiment of the device according to the invention is characterized in
that
by means of a gripper the workpiece is positioned in the first and/or second
gripping
device, and/or is removed from the same.
By such gripper an automated collecting from storage of a workpiece to be
machined is possible, as well as the transfer of the workpiece of the first
gripping
device to the second gripping device and the subsequent removal of the
machined
workpiece from the second gripping device and the transfer to another storage.
The invention further relates to a machining device that is characterized in
that
the machining device is provided with at least one tool for making the element
comprising a dovetail-shaped mounting element in the workpiece that is fixed
in the
first gripping device, the first and second gripping devices being located on
different
sides of a gripping table that is swivelling about a swivel axle, which
gripping table is
at least swivelling from a first position, in which the workpiece can be
machined for
making the dovetail-shaped mounting element in the workpiece, towards a second
position in which the workpiece that is fixed in the second gripping device by
means
of the dovetail-shaped mounting element can be machined with the tool, and
vice
versa.
By such machining device an efficient machining of a workpiece becomes
possible, because of which the machining device is suited for small series of
workpieces to be machined, without the necessity of interim storage of the
workpieces en/or replacements of gripping devices.
An embodiment of the machining device according to the invention is
characterized in that the machining device is provided with different first
gripping
devices, which are respectively suited for fixing an cross cut side and a
longitudinal
side of a cylindrical workpiece.
Hereby the cylindrical workpiece to be machined can be made in the cross cut
side or the longitudinal side, according to preference.
Another embodiment of the machining device according to the invention is
characterized in that the first gripping device is provided with a recess that
is limited
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by at least two abutment surfaces including an angle with one another, as well
as
gripping surface that is movable with respect to the abutment surfaces.
Preferably the
abutment surfaces and the gripping surface include herewith an angle of about
600
with one another.
Such gripping device is particularly suited for fixing end cross cut sides of
a
cylindrical workpiece, in which case workpieces with different diameters can
simply
be fixed because of the movable gripping surface. By the angle of about 600
the
contact points of the abutment surfaces and the gripping surface with the
workpiece
will be regularly distributed along the circumference of the workpiece.
Yet another embodiment of the machining device according to the invention is
characterized in that the first gripping device comprises a central portion
and two
gripping parts located on both sides of the central portion, each being
separately
movable from the central portion and towards the central portion. Preferably
the
central portion and the gripping part comprise gripping surfaces that include
an
angle of about 300 with one another.
Such gripping device is particularly suited for fixing the longitudinal side
of a
cylindrical workpiece, the gripping surfaces preferably extending past the
centre of
the workpiece.
The invention will be described in further detail with reference to the
drawings, in
which:
Fig. 1 shows a perspective view of an embodiment of a gripping table of a
machining device according to the invention,
Fig. 2 shows a perspective view of a first embodiment of a first gripping
device
according to the gripping table illustrated in Fig. 1,
Fig. 3 shows a side view of the gripping device illustrated in Fig. 2,
Fig. 4 shows a side view of the gripping device illustrated in Fig. 2, in a
different
gripping position,
Fig. 5 shows a perspective view of a second embodiment of a first gripping
device of the gripping device illustrated in Fig. 1,
Fig. 6 shows a plan view of the gripping device illustrated in Fig. 5,
Fig. 7 shows a perspective view of the gripping table illustrated in Fig. 1,
which is
provided with a second gripping device, in which workpieces are fixed in the
first and
second gripping devices,
Fig. 8 shows another perspective view of the gripping table illustrated in
Fig. 7,
Fig. 9 shows the gripping table illustrated in Fig. 1, where the gripping
table is
swiveled over goo.
In the figures like parts are referred to by like reference numbers.
Fig. 1 shows a perspective view of a gripping table 1 of a machining device
according to the invention. The gripping table 1 bearing-mounted in the
machining
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device, is swivelling about a swivel axle 2, by which the gripping table 1 is
swivelling
in, and opposite to, the direction indicated by arrow Pi. The machining device
further
includes at least one machining unit, such as a cutter, a drill etc. and means
for
moving the machining unit with respect to the X-, Y-, Z- and q)-directions of
the
5 gripping table i. Such machining device, by which movements in five
directions can
be performed, is called a 5-axle machining device. A 5-axle machining device
is
known per se and is therefore not shown and its operation will therefore not
be
explained in further detail.
The gripping table 1 of the machining device according to the invention
comprises a frame 3 that at one end is provided with a main axis 4, by means
of
which the gripping table 1 is bearing-mounted in the machining device and can
be
driven to be rotated in, or opposite to, the direction indicated by the arrow
Pi.
The frame 3 comprises four sides 5, 6, 7, 8 that extend parallel to the swivel
axle
2. The parallel extending sides 5, 7 are each provided with a gripping device
9, io,
that is respectively suited for fixing a longitudinal side and an cross cut
side of a
cylindrical workpiece (see Figs. 7 and 8). Side 6 is provided with a clamping
unit 11,
which is suited for clamping a gripping device 12 (see Figs. 7 and 8). The
clamping
unit 11 is rotatable about a rotation axle extending transversely to the side
6 and the
swivel axle 2.
Figs. 2 - 4 show various views of the gripping device 9 that is detachably
connected to the side 5 of the frame 3. The gripping device 9 comprises a
bottom
plate 13, a central portion 14, centrally connected to the bottom plate, and
gripping
parts 15, 16, which are located on both sides of the central portion 14. On
one side
that is turned towards the gripping part 15, the central portion 14 is
provided with a
curved supporting surface 17 and an abutting gripping surface 18 that inclines
in the
direction of gripping part 15. The gripping surface 18 includes an angle a
with the
horizontal 19. The supporting surface 17 includes an angle of 110 -120 with
the
gripping surface 18. On one side that is turned towards the gripping part 16,
the
central portion 14 is provided with a curved supporting surface 20 and an
abutting
gripping surface 21 that inclines in the direction of gripping part 16. The
gripping
surface 21 includes an angle a with the horizontal 19. The curved supporting
surface
17 of the gripping part 15 is situated closer to the bottom plate 13 than the
curved
supporting surface 20 of the gripping part 16. Due to the curvature of the
curved
supporting surfaces 17, 20 the range of the gripping device 9 is relatively
large. The
gripping parts 15, 16 are each provided with respectively gripping surface 22,
23
inclining in the direction of the central portion 14. The gripping surfaces
22, 23
include an angle a with the horizontal 19. The angle a is preferably 750 tot
88 and
more preferably 85 . The gripping part 15 is movable with respect to the
central
portion 14 in, and opposite to, the direction indicated by arrow P2. The
distance L2
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between the gripping surfaces 18, 22 is herewith e. g. adjustable between 8o
and 160
mm. The gripping part 16 is movable with respect to the central portion 14 in,
and
opposite to, the direction indicated by arrow P3. The distance Li between the
gripping surfaces 21, 23 is herewith e. g. adjustable between 4o and 10o mm.
The
gripping part 15 in cooperation with the central portion 14 is suited for
fixing
longitudinal sides of cylindrical workpieces with a diameter of e. g. 90 to
150 mm,
whereas the gripping part 16 in cooperation with the central portion 14 is
suited for
fixing longitudinal sides of cylindrical workpieces with a diameter of e. g.
50 to 90
mm.
Figs. 5 and 6 show views of the gripping device 1o that is detachably
connected
to the side 7 of the frame 3. The gripping device 1o comprises a bottom plate
30, an
abutment part 31 that is connected to the bottom plate 3o and a gripping part
32 that
is slidable with respect to the abutment part 31 in, and opposite to, the
direction
indicated by arrow P4. The gripping part 32 is slidably bearing-mounted over
piston
rods 33, and is movable by means of a hydraulic drive (not illustrated). The
abutment
part 31 comprises a recess 34 that is limited by at least two abutment
surfaces 35
including an angle of 600 with one another. On one side that is turned towards
the
recess 34, the gripping part 32 comprises a gripping surface 36 that is
located
centrally with respect to the abutment surfaces 35. The gripping surface 36
preferably
includes an angle of preferably 600 with the abutment surfaces 35. The
gripping
surface 36 is movable with respect to the abutment surfaces 35, the distance
L3
between the gripping surface 36 and point 37 of the recess 34 that is most
remote
from the gripping surface 37 being adjustable to hold workpieces with a
diameter of
between 4o and 200 mm, for example.
Figs. 7 and 8 show views of the gripping table 1. Side 6 is provided with the
clamping unit 11, on which the gripping device 12 is detachably mounted. The
gripping device 12 comprises a bottom plate 40, as well as two gripping parts
41, 42
that are movably connected to the bottom plate 40 in, and opposite to,
directions
indicated by arrow P5. The gripping parts 41, 42 are provided with gripping
edges 43
that are apt to be brought into grip with a dovetail-shaped mounting element
44 on a
workpiece 45. Such gripping parts 41, 42 are known per se.
The operation of the machining device according to the invention is as
follows.
By means of a gripper (not illustrated) a workpiece 45 to be machined, like e.
g. a
cylindrical workpiece 45, is lifted. If at the cross cut side 46 of the
workpiece 45 a
dovetail-shaped mounting element 44 needs to be made, the workpiece 45 is
moved
to the gripping device 10, while the end of the workpiece 45 that is averted
from the
cross cut side 46 is positioned in the recess 34 against the abutment surfaces
35.
Subsequently the gripping surface 36 is pressed against the longitudinal side
47 of the
workpiece 45, due to which the workpiece 45 is fixed firmly between the
abutment
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surfaces 35 and the gripping surface 36. If in the longitudinal side 47 of the
workpiece
a dovetail-shaped mounting element 44 needs to be made, the workpiece 45 is
moved
to the gripping device 9. Dependent on the diameter of the workpiece 45, the
workpiece 45 is positioned between the central portion 14 and the gripping
part 15 or
the gripping part 16. Then the gripping part 15, 16 is moved to the central
portion 14,
the workpiece being firmly fixed between the supporting surface 17; 20 and the
gripping surfaces 18, 22; 21, 23.
It is also possible to position workpieces 45 with different diameters next to
one
another in the gripping device 9.
Subsequently the gripping table 1 is swiveled about the swivel axle 2, as e.
g. is
illustrated in Fig. 9, where the gripping device 9, 1o with the workpiece 45,
that is
provided with a mounting element 45, is directed towards the machining unit of
the
machining device. In order to make a dovetail-shaped mounting element 44 an
adequate cutter will be used here.
After dovetail-shaped mounting elements 44 have been made in the workpiece
45, the workpiece 45 is lifted from the gripper device 9, 10 by means of the
gripper,
and is moved tot the gripping device 12. Here the workpiece 45 is fixed
between the
gripping parts 41, 42 by means of the dovetail-shaped mounting elements 44.
The
gripping table 1 is swiveled once more, so that the workpiece 45 that is fixed
in the
gripping device 12 can be machined.
The gripping devices 9, 1o form first gripping devices that are suited for
fixing a
workpiece that is not yet provided with a mounting element. If desired it is
also
possible to provide such first gripping device to side 8 extending parallel to
side 6,
which e. g. is suited for fixing rectangular workpieces.
The gripping in the first gripping device can also take place in another way
like
e. g. by means of magnetic power.
It is also possible to mount bearings on both sides of the rotatable frame 3.
