Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2001-06-01
2003-09-02
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S181000, C709S200000, C318S566000
Reexamination Certificate
active
06615103
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a maintenance system for a machine tool including driver mechanisms such as a spindle unit, a tool clamp unit and an automatic tool changer and a controller for controlling operations of the driver mechanisms, the maintenance system being adapted to perform a management operation on the operating life expectancies of the driver mechanisms.
2. Description of the Prior Art
One exemplary machine tool of the aforesaid type is illustrated in FIG.
10
. The machine tool
21
is a so-called vertical machining center. The machine tool
21
illustrated in
FIG. 10
includes: a bed
22
; a column
23
provided upright on the bed
22
; a spindle unit
24
rotatably supporting a spindle
25
and supported by the column
23
in a vertically movable manner; a table
26
provided below the spindle unit
24
on the bed
22
; a tool magazine
40
provided on the left side of the spindle unit
24
; an automatic tool changer
42
provided at a lower end of the tool magazine
40
for exchanging a tool T attached to the spindle
25
and a tool T stored in a retainer pot
41
of the tool magazine
40
; a clamp unit
57
as shown in
FIG. 11
for fixing the tool T to a front end (lower end) of the spindle
25
; and a numerical controller
80
as shown in
FIG. 13
for controlling the respective components of the machine tool
21
.
As shown in
FIG. 11
, the spindle unit
24
includes the spindle
25
, a housing
50
rotatably supporting the spindle
25
via a bearing
51
, a cover
52
provided at a front end of the housing
50
, and a driving motor (not shown) for rotatively driving the spindle
25
. A taper hole
25
a
for receiving the tool T is formed in the front end of the spindle
25
(as seen in the direction of an arrow D).
As shown in
FIG. 11
, the clamp unit
57
includes a collet
53
provided in the spindle
25
for holding a pull stud (holder portion) Ta of the tool T fitted in the taper hole
25
a
of the spindle
25
, a push-pull rod
54
engaged with the collet
53
, a driving rod
60
coupled to the push-pull rod
54
, coned disc springs
61
for biasing the driving rod
60
in the direction of an arrow E, and a hydraulic cylinder (not shown) for moving the driving rod
60
in the direction of the arrow D.
When a hydraulic pressure is supplied to the hydraulic cylinder (not shown), the clamp unit
57
moves the driving rod
60
in the direction of the arrow D against a biasing force of the coned disc springs
61
, whereby the push-pull rod
54
and the collet
53
are moved in the direction of the arrow D to open a front end of the collet
53
which holds the pull stud Ta of the tool T. Thus, the tool T can be withdrawn from the taper hole
25
a
of the spindle
25
. Where the tool T is fitted in the taper hole
25
a
of the spindle
25
in this state, the pull stud Ta of the tool T is inserted in the collet
53
. When the supply of the hydraulic pressure to the hydraulic cylinder (not shown) is stopped in this state, the driving rod
60
is moved in the direction of the arrow E by the biasing force of the coned disc springs
61
to close the collet
53
, whereby the tool T attached to the spindle
25
is held by the collet
53
with the pull stud Ta thereof inserted in the direction of the arrow E.
As shown in
FIG. 12
, the automatic tool changer
42
includes: a rotation shaft
43
provided parallel to the spindle
25
; a changer arm
44
fixed to a lower end of the rotation shaft
43
; roller-shaped cam followers
70
provided around an outer circumference of a middle portion of the rotation shaft
43
at a predetermined angular interval for rotating the rotation shaft
43
about an axis thereof; a lever-shaped cam follower
71
provided in engagement with the rotation shaft
43
below the cam followers
70
for moving the rotation shaft
43
along the axis thereof; a roller gear cam
72
having guide grooves formed in an outer circumference thereof for engagement with the cam followers
70
, and a guide groove formed in a side face thereof for engagement with the cam follower
71
; a gear
76
integrally fixed to the roller gear cam
72
; and a motor
73
for generating a rotative driving force which is transmitted to the gear
76
via transmission gears
74
,
75
and the like. The cam followers
70
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
72
. The cam follower
71
includes an engagement roller rotatably supported by a bearing for engagement with the guide groove formed in the side face of the roller gear cam
72
.
In the automatic tool changer
42
, the rotative driving force is transmitted from the motor
73
to the roller gear cam
72
via the gears
74
,
75
,
76
and the like to rotate the roller gear cam
72
about the axis thereof, whereby the rotation shaft
43
is rotated about the axis thereof by the action of the cam followers
70
engaged with the roller gear cam
72
and is axially moved by the action of the cam follower
71
engaged with the roller gear cam
72
. The action of the rotation shaft
43
causes the changer arm
44
to perform a tool changing operation.
As shown in
FIG. 13
, the numerical controller
80
includes a CNC
81
, a PLC
82
, an input/output interface
83
and the like, and is connected to an external control circuit
84
via the input/output interface
83
. The control circuit
84
is connected to the spindle unit
24
, the automatic tool changer
42
and the clamp unit
57
. The CNC
81
executes a machining program stored therein to control basic operations of the machine tool
21
such as axial movements of the spindle unit
24
and the table
26
. The PLC
82
includes a spindle controlling section
82
a
, a clamp controlling section
82
b
, a changer controlling section
82
c
and the like, and controls auxiliary operations of the machine tool
21
such as operations of the spindle unit
24
, the automatic tool changer
42
and the clamp unit
57
upon reception of commands applied from the CNC
81
.
More specifically, the spindle controlling section
82
a
drives and controls a spindle motor (not shown) upon reception of a rotating command applied from the CNC
81
to rotate the spindle
25
shown in
FIG. 11
at a commanded speed in a commanded rotation direction. The clamp controlling section
82
b
drives the hydraulic cylinder (not shown) of the clamp unit
57
upon reception of a tool clamp command or a tool unclamp command applied from the CNC
81
to clamp or unclamp the tool T attached to the spindle
25
. The changer controlling section
82
c
drives the automatic tool changer
42
upon reception of a tool changing command applied from the CNC
81
to perform the tool changing operation.
As described above, the spindle
25
is rotatably supported by the bearing
51
, and the cam followers
70
,
71
also employ the bearings. The bearings naturally each have a limited service durability due to the wear and the like of rolling element thereof and, hence, have a finite service life. Further, the clamp unit
57
employs the coned disc springs
61
, which naturally have a limited fatigue durability because the coned disc springs
61
are repeatedly subjected to a load and, hence, have a finite service life.
Where the service lives of the bearing
51
, the bearings of the cam followers
70
,
71
and the coned disc springs
61
end during operation to result in breakage thereof, the time required for recovery from the breakage is prolonged depending on operating conditions thereof at the breakage. Moreover, there is a danger of breakage of other components depending on the conditions of the breakage. The breakage of a greater number of components further prolongs the time required for repair of the components. This disadvantageously reduces the availability of the machine tool. If there are no spare components, the machine tool cannot be repaired until replacement components are delivered. This further reduces the avail
Akamatsu Yoshiaki
Fujishima Makoto
Armstrong Westerman & Hattori, LLP
Lee Douglas S.
Moki Seiki Co., Ltd.
Picard Leo
LandOfFree
Machine tool maintenance system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Machine tool maintenance system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Machine tool maintenance system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3061954