Tool changing – Tool transfer to or from matrix – Indexing matrix
Reexamination Certificate
2000-03-31
2001-05-08
Briggs, William (Department: 3722)
Tool changing
Tool transfer to or from matrix
Indexing matrix
C211S001520, C483S058000
Reexamination Certificate
active
06228008
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a tool carousel for use in a tool changer on a machining centre.
2. Background Art
A tool carousel comprises a wheel-like structure which, in use, carries a series of individually removable tools. In most cases, the carousel comprises a rotational index means, so as to enable any selected one of the tools carried by the carousel wheel to be located at a predetermined rotational position, whereat a transfer mechanism can present the selected tool to a machine tool for use in a machining operation.
FIG. 1
shows a typical example of a machining centre which includes a tool carousel. As can be seen, the tool carousel wheel
1
is mounted upon a horizontal rotational axis adjacent a transfer mechanism
2
. Referring to
FIG. 2
, it will be seen that the transfer mechanism
2
comprises a transfer arm
4
for transferring tools between the carousel wheel
1
and a machine tool spindle
3
. The transfer arm rotates about a central rotation axis
8
and has a tool grip at each end.
As can be best seen in
FIG. 3
, the carousel wheel
1
comprises a plurality of circumferentially consecutive pots
6
, each of which is used for storing a respective tool. In the storage position, each of the pots orientates its respective tool with its axis generally horizontal. However, when a tool is specified by the machine control, the carousel wheel
1
is rotated until the correct tool is located in the transfer position
5
, and the pot containing this tool is then rotated through 90° about a horizontal axis which is perpendicular to the rotational axis of the carousel wheel. As a consequence, the pot hangs vertically down and in the manner of the pot designated
7
. In this position, the tool has its axis parallel to the centre line of the machine tool spindle
3
. Once the pot is in this position, the transfer arm
4
is able to rotate about its vertical rotation axis
8
and remove the selected tool from its pot
7
whilst simultaneously removing any existing tool from the spindle nose
3
. As it continues to rotate, the position of the two tools is reversed, the selected tool is presented to the spindle nose, and the deselected tool is presented to the appropriate pot on the carousel
1
. That pot is then rotated back up through 90°, so that the deselected tool is stored with its axis inclined horizontally, in common with the other tools stored in the carousel.
Tools for use in a machine tool are invariably heavy, metal items and the carousel wheel of a tool carousel therefore has to be strong and sturdy enough to carry all of the tools without buckling or breaking over a long period of time during which the tool carousel is required to operate reliably, without breakdown. It has therefore been the practice to form carousel wheels of known tool carousels from metal.
FIG. 4
shows a vertical section through a known tool changer incorporating such a carousel. From the figure, it can be seen that a pot
105
has a generally cylindrical form and is attached to the hub
124
of a carousel wheel via a rotation axis
117
. The pot
105
is fitted with a collar
119
at an end thereof which is situated at the top of the pot when it is rotated through 90° about the axis
117
at the tool access position, as shown in dotted lines in FIG.
4
. Axially inwardly of the collar
119
, there is located a retention collar
104
that comprises a central axial bore into which a number of balls
100
are resiliently urged to project. In use, a pull-stud of a tool holder is located within the bore and gripped by the balls
100
. When the tool is to be extracted, this is achieved by axial displacement of an extractor
118
which can be axially pushed into the bore, to force the pull-stud out.
A dog
102
is provided in the mouth of the pot
105
for retaining the correct orientation of the tool holder. A tool identification tag is provided at
101
.
The pot
105
is integrally formed with an arm
103
. The arm
103
projects radially from the side of the pot body and terminates with a transversely extending section, upon which is fitted a rotatable pusher wheel
108
and a bearing
109
. The pot is retained in the storage position shown in
FIG. 4
by the action of the bearing
109
, which bears against a bearing plate
125
. The plate is provided with a local slot at the pot release position, thus enabling the pot to be rotated about the axis
117
, when it is located there. The pusher wheel
108
is adapted to fit within a mouth
123
of a fork
122
mounted at the end of a rod
121
of a vertically aligned piston
120
. As the carousel wheel rotates, the pusher wheel
108
of each pot assembly consecutively enters the mouth
123
of the fork
122
from the side. When the appropriate tool holder is in position, pneumatic cylinder
120
is actuated, so as to cause the piston rod
120
to extend vertically downwards. As this happens, the pusher wheel
108
is urged downwardly by virtue of the fact that it is constrained within the mouth
123
of the fork
122
. This downward movement causes the pot
105
to rotate about the axis
117
, thereby eventually bringing the tool holder into the position shown in chain-dotted line in FIG.
4
. From this position, a transfer arm can transfer the tool to the machine head, as generally described in relation to
FIGS. 1
to
3
.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a tool carousel which is easier and less expensive to manufacture and, if necessary, repair than that of the known tool changer.
According to a first aspect of the invention there is provided a tool carousel according to claim
1
. Preferred features of this aspect of the invention are set out in claims
2
to
21
. According to a second aspect of the invention, claim
25
provides a lifting and lowering mechanism for a tool carousel wheel. A third aspect of the invention is set out in claim
28
and provides a drive mechanism for a tool carousel. Preferred features of the various aspects of the invention are set out in the dependent claims.
REFERENCES:
patent: 4008518 (1977-02-01), Hague et al.
patent: 4190947 (1980-03-01), Sato et al.
patent: 4356621 (1982-11-01), Tomita et al.
patent: 4358888 (1982-11-01), Zankl et al.
patent: 4398136 (1983-08-01), Tanaka et al.
patent: 4426763 (1984-01-01), Hornok et al.
patent: 4489629 (1984-12-01), D'Andrea
patent: 4631684 (1986-12-01), Akasofu et al.
patent: 5300006 (1994-04-01), Tanaka et al.
Mandalia Harish Devji
Pollington Andrew Roy
Bridgeport Machines Limited
Briggs William
Ohlandt Greeley Ruggiero & Perle L.L.P.
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