Data processing: generic control systems or specific application – Generic control system – apparatus or process – Specific compensation or stabilization feature
Reexamination Certificate
1998-04-27
2001-10-09
Sheikh, Ayaz (Department: 2155)
Data processing: generic control systems or specific application
Generic control system, apparatus or process
Specific compensation or stabilization feature
C700S069000, C700S070000, C318S560000, C318S561000, C318S568100, C318S568220, C318S600000
Reexamination Certificate
active
06301511
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a numeric control unit for a turning mechanism which turns a turning body around a designated turning shaft through a non-linear transmitting mechanism by a driving source moving in a non-circular movement.
2. Description of the Related Art
Conventionally, in a machine tool or the like which is provided with a turning mechanism which turns a turning body around a designated turning shaft, a turning mechanism which has a driving source to move in a linear motion, and a transmitting mechanism which transmits the linear motion by the driving source to the turning body. As for a transmitting mechanism, a rack and pinion mechanism, a worm-gear mechanism and so on are used.
Among such turning mechanisms, there is a turning mechanism which turns a turning body using a cam mechanism, for instance, a turning mechanism shown in Japanese Patent Application No. Hei 8-198035.
This turning mechanism
1
is formed, as shown in
FIG. 12
, including a turning bodies
12
supported by a base member
11
as possible to turn, a driving source
13
which turns the turning body
12
and a transmitting mechanism
14
which transmits the movement of the driving source
13
to the turning body
12
.
The turning body
12
is supported by a supporting shaft
15
as possible to turn around a turning shaft A to a base member
11
, and on the tip thereof, a concave portion
121
is formed to engage in a connecting shaft
143
which will be explained later.
A main shaft head
122
in a built-in motor system is provided near the turning shaft A of the turning body
12
, and it becomes possible that the main shaft head
122
turns in accordance with the turning movement of the turning body
12
to perform various processing on a work piece.
The driving source
13
is provided with: a servo-motor
131
; a pinion gear
132
which meshes with a gear wheel provided on the tip of the revolving shaft of the servo-motor
131
; a feed screw rod
133
rotated by the pinion
132
in accordance with the revolution of the revolving shaft of the servo-motor
131
; and a feed nut
134
which screws with the feed screw rod
133
, and moves in a linear movement along the extending direction of the feed screw rod
133
.
A transmitting mechanism
14
which transmits a linear movement of the feed nut
134
of the driving source
13
to the turning body
12
is comprised with a horizontal slider
141
, a vertical slider
142
, and a connecting shaft
143
.
The horizontal slider
141
is attached in a movable manner in the extending direction of the horizontal guide
111
which is linearly mounted on the base member
11
, and a vertical guide
141
A perpendicularly extending into the extending direction of the horizontal guide
111
is constructed on the upper surface of the slider
141
.
The vertical slider
142
is attached in a movable manner in the direction of the vertical guide
141
A and the connecting shaft
143
which engages with the concave portion
121
of the turning shaft
12
, is provided on the upper surface of the vertical slider
142
.
The feed nut
134
of the driving source
13
is jointly fixed to the horizontal slider
141
on the right.
The horizontal sliders
141
provided on the two turning bodies
12
respectively, are connected to each other by a connecting rod
144
, and according to the turning movement of the turning body
12
shown in the right side on
FIG. 12
, the other turning body
12
also turns.
The turning mechanism
1
behaves as follows.
1) When the servo-motor turns, the feed screw rod
133
rotates through the pinion gear
132
.
2) The feed nut
134
moves along the direction extending from the feed screw rod
133
by the rotation of the feed screw rod
133
.
3) In accordance with the movement of the feed nut
134
, the horizontal slider
141
moves and the turning body
12
turns through the connecting shaft
143
.
While the horizontal slider
141
is moving, the connecting shaft
143
moves with the vertical slider
142
along the vertical guide
141
A to maintain engagement with the concave portion
121
of the turning body
12
.
As shown in
FIG. 13
, a path
143
A of the connecting shaft
143
form an arc in &thgr; direction around the turning shaft A to a path
134
A of the feed nut
134
in the X direction.
According to the turning mechanism
1
, a linear movement of the driving source
13
can be transmitted to the turning movement of the turning body
12
through a simple motion along the guides
111
and
141
A of the horizontal slider
141
and the vertical slider
142
.
Therefore, a turning mechanism having an extreme durability can be formed with no fear of a turning motion failure caused by the abrasion of the mesh portion as in the case of a rack and pinion mechanism or a worm gear mechanism.
When plural turning bodies
12
in a rack and pinion transmitting mechanism and the like are placed adjacent to each other, it is necessary to take a large space interval for each element so that the gear of the adjacent transmitting mechanism does not interfere with each other. On the other hand, when the turning mechanism
1
described above is used, there is no need to take it into consideration, and the turning bodies
12
can be placed near to each other, so that a machine tool having plural turning bodies can be made small size.
In order to machine a work piece with high precision with the turning mechanism
1
in a machine tool and the like, it is necessary to enhance the positioning precision of the turning body to the inputted turn angle signal, and stabilize the turn velocity of the turning body with high precision. Particularly, in a multi-shaft high precision machine tool for contour processing such as a profiler and the like, achievement of a high precision in positioning and turn velocity is an important subject.
However, as shown in
FIG. 13
, since such a turning mechanism
1
converts a linear movement of the feed nut
134
into a turn movement of the turning body
12
, the distance between the turning shaft A and a driving point of the straight line (the position of the feed nut
134
) of the driving source
13
varies in accordance with the turn angles &thgr;. This means that even when the feed nut
134
moves with constant velocity along the path
134
A, the turn velocity of the turning body
12
varies.
Therefore, in order to turn the turning body
12
while maintaining constant turn velocity, the linear movement of the driving source
13
must be controlled to change in response to the turn angles &thgr;.
More specifically, since the linear movement of the driving source
13
is converted to the turning movement of the turning body
12
, the driving source
13
must be driven with trigonometric-functionally changing the movement velocity of the driving source
13
.
When a positional error (droop) Ex arises at the driving point of the straight line of the driving source
13
, a positional error E
&thgr;
of the turning body which follows the linear movement varies in accordance with the turn angles.
Accordingly, the positional error E
&thgr;
must be controlled in response to the angles &thgr; to be the same as in the case of direct driving through the revolution driving source.
Such a subject is grasped not only in the turning mechanism
1
which transmits the movement of the driving source
13
to the turning body through the transmitting mechanism
14
, but also in the turning mechanism which applies a non-linear transmitting mechanism such as a link mechanism and the like.
In a numerical control device of a turning mechanism which turns a turning body with a non-circularly-moving driving source through a non-linear transmitting mechanism, it is an object of the present invention to provide a numerical control device of a turning mechanism which enables it to stabilize the turn velocity of the turning body with a high precision and to control the droop of the driving source in a similar manner to the case when driven with a revolution driving source.
SUMMARY OF THE INVENTIO
Fujita Jun
Hayashi Hideki
Inoue Kiyoshi
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Jean Frantz
Sheikh Ayaz
Toshiba Kikai Kabushiki Kaisha
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