Automatic tool changer

Details Automatic tool changer Automatic tool changer

2001-05-07

2003-01-21

Smith, Scott A. (Department: 3721)

Tool driving or impacting

Automatic control of power operated means

C173S213000, C173S217000, C173S171000

Reexamination Certificate

active

06508314

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an automatic tool changer for a machine tool and, more particularly, to an automatic tool changer which is adapted to rotate a changer arm by engagement of a cam and cam followers.
2. Description of the Prior Art
One exemplary machine tool having an automatic tool changer of the aforesaid type will be explained with reference to
FIGS. 3
to
5
. The machine tool
12
illustrated in
FIG. 3
is a so-called vertical machining center. The machine tool
12
includes: a bed
13
; a column
14
provided upright on the bed
13
; a spindle head
15
supported by the column
14
in a vertically movable manner; a spindle
16
supported by the spindle head
15
and rotatable about an axis thereof; a table
17
provided below the spindle
16
on the bed
13
; a tool magazine
21
provided on the left side of the spindle head
15
; a tool changer mechanism
26
provided at a lower end of the tool magazine
21
for exchanging a tool T attached to the spindle
16
with a tool T stored in a retainer pot
23
of the tool magazine
21
; and a numerical controller
50
as shown in
FIG. 5
for controlling the respective components of the machine tool.
The tool magazine
21
includes: a plurality of retainer pots
23
for retaining tool holders TH; a retainer disk plate
24
for retaining the retainer pots
23
at a predetermined interval circumferentially thereof; and a cover
22
surrounding the retainer pots
23
and the retainer disk plate
24
.
As shown in
FIG. 4
, the tool changer mechanism
26
includes: a rotation shaft
27
provided parallel to the spindle
16
(see FIG.
3
); a changer arm
28
fixed to a lower end of the rotation shaft
27
and having tool holding portions
28
a
provided at opposite ends thereof; roller-shaped cam followers
33
provided around an outer circumference of a middle portion of the rotation shaft
27
at a predetermined angular interval for rotating the rotation shaft
27
about an axis thereof; a lever-shaped cam follower
34
provided in engagement with the rotation shaft
27
below the cam followers
33
for moving the rotation shaft
27
along the axis thereof; a roller gear cam
35
having guide grooves formed in an outer circumference thereof for engagement with the cam followers
33
, and a guide groove formed in a side face thereof for engagement with the cam follower
34
; a gear
41
integrally fixed to the roller gear cam
35
; and a motor
36
for generating a rotative driving force which is transmitted to the gear
41
via transmission gears
38
,
39
and the like. The cam followers
33
each include an engagement roller rotatably supported by a bearing for engagement with the guide groove formed in the outer circumference of the roller gear cam
35
. The cam follower
34
includes an engagement roller rotatably supported by a bearing for engagement with the guide groove formed on the side face of the roller gear cam
35
.
With this arrangement, the rotative driving force is transmitted from the motor
36
to the roller gear cam
35
via the gears
38
,
39
,
41
to rotate the roller gear cam
35
about the axis thereof, whereby the rotation shaft
27
is rotated about the axis thereof by the action of the cam followers
33
engaged with the roller gear cam
35
and is axially moved by the action of the cam follower
34
engaged with the roller gear cam
35
. The action of the rotation shaft
27
causes the changer arm
28
to perform a tool changing operation which will be described later.
As shown in
FIG. 5
, the numerical controller
50
includes a computerized numerical controller (CNC)
54
, a programmable logic controller (PLC)
55
, an input/output interface
56
and the like, and is connected to an external control circuit
51
via the input/output interface
56
. The control circuit
51
is connected to an operation panel
52
, the tool changer mechanism
26
and the like.
The CNC
54
executes a machining program stored therein to control basic operations of the machine tool
12
such as axial movements of the spindle head
15
and the table
17
, and display of a CRT
11
. The PLC
55
includes a changer controlling section
57
and the like, and controls auxiliary operations of the machine tool
12
such as operations of the tool magazine
21
and the tool changer mechanism
26
. The CRT
11
typically displays the machining program and the coordinates of the current position of a tool.
As described above, the changer controlling section
57
controls the operation of the tool changer mechanism
26
via the control circuit
51
. The changer controlling section
57
usually drives the tool changer mechanism
26
to perform the tool changing operation in response to a tool changing command from the CNC
54
executing the machining program. The tool changing command can also be manually inputted from the operation panel
52
to cause the tool changer mechanism
26
to perform the tool changing operation. In this case, the tool changing command inputted from the operation panel
52
is transmitted to the CNC
54
via the control circuit
51
, the input/output interface
56
and the PLC
55
. Then, the tool changing command is output ted to the changer controlling section
57
from the CNC
54
. Upon reception of the tool changing command, the changer controlling section
57
drives the tool changer mechanism
26
for the tool changing operation.
The automatic tool changer is constituted by the tool changer mechanism
26
, the changer controlling section
57
and the like. The tool T attached to the spindle
16
is automatically exchanged with another tool in the following manner by the automatic tool changer.
First, a retainer pot
23
which retains a desired tool holder TH on the tool magazine
21
is moved to a changing position thereby to be ready for tool exchange. Then, the cam followers
33
rotate the rotation shaft
27
by 90 degrees about the axis thereof in a normal rotation direction. The changer arm
28
is rotated together with the rotation shaft
27
by 90 degrees, whereby the tool holder TH attached to the spindle
16
(hereinafter referred to as “current tool holder”) and the tool holder TH in the retainer pot
23
(hereinafter referred to as “next tool holder”) are respectively held by the tool holding portions
28
a
provided at the opposite ends of the changer arm
28
.
In turn, the cam follower
34
advances the rotation shaft
27
along the axis thereof, whereby the current tool holder TH and the next tool holder TH held by the changer arm
28
are respectively removed from the spindle
16
and the retainer pot
23
. Thereafter, the cam followers
33
further rotate the rotation shaft
27
by 180 degrees in the normal rotation direction, and the cam follower
34
retracts the rotation shaft
27
along the axis thereof. Thus, the next tool holder TH is attached to the spindle
16
, and the current tool holder TH is retained in the retainer pot
23
.
The cam followers
33
rotate the rotation shaft
27
by 90 degrees in a reverse direction to return the rotation shaft
27
to an original position. Then, the retainer pot
23
is transported to the previous indexing position, and stored within the cover
22
. Thus, the current tool holder TH attached to the spindle
16
is exchanged with the next tool holder TH stored in the tool magazine
21
.
As described above, the cam followers
33
,
34
each employ the bearing, which naturally has a limited service durability due to the wear and the like of rolls thereof and, hence, has a finite service life. However, the conventional automatic tool changer is not adapted to detect the end of the service life of the bearings. Therefore, the service life of the bearings of the cam followers
33
,
34
may end during the operation of the automatic tool changer, resulting in breakage of the bearings. Depending on operating conditions of the cam followers
33
,
34
, the time required for recovery from the breakage is disadvantageously prolonged.
Where the bearings of the cam followers
33
,

Affiliated with

Also associated with

Rating

Automatic tool changer does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Automatic tool changer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Automatic tool changer will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3050121