Control method for bar material feeder of NC lathe and NC lathe

Details Control method for bar material feeder of NC lathe and NC lathe Control method for bar material feeder of NC lathe and NC lathe

2002-06-04

2003-12-16

Paladini, Albert W. (Department: 2125)

Data processing: generic control systems or specific application

Specific application, apparatus or process

Product assembly or manufacturing

C082S127000, C029S02700R

Reexamination Certificate

active

06665579

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a method of controlling a bar supplying apparatus provided for a numerically controlled lathe, for continuously machining products while feeding a long bar on a predetermined length unit basis through a through hole in a main spindle.
BACKGROUND ART
A bar supplying apparatus for supplying a long bar through a through hole formed on the axis of a main spindle of a numerically controlled lathe (hereinbelow, described as NC lathe) is known. The bar supplying apparatus can continuously machine a plurality of products from a single bar by repeating a process of allowing the tip of the bar project by a predetermined length from a guide bush provided on the axis or in front of the main spindle, machining the tip of the bar with a tool attached to a tool post, cutting off a product from the tip of the bar by a cutting-off tool, feeding the bar by a predetermined length, and similarly machining the tip of the bar.
FIG. 9
shows the configuration of a conventional NC lathe having such a bar supplying apparatus.
As shown in the diagram, an NC lathe
110
has a headstock
113
which can move forward and backward in the same direction as the Z axis, a main spindle
112
rotatably supported by the headstock
113
, in which a through hole
112
a
into which a bar W is inserted along a main spindle axis C is formed, a chuck
117
for holding the bar W, provided at the tip of the main spindle
112
, a guide bush
116
provided in front of the headstock
113
(in the left part of FIG.
9
), for rotatably supporting the tip of the bar W, and a tool post
114
to which a plurality of tools T are attached.
The tools T attached to the tool post
114
include not only a single point tool for machining the tip of the bar W projected from the guide bush
116
but also a cutting-off tool for cutting off a product formed at the tip of the bar W, and a positioning tool for positioning the bar W on the main spindle axis C by making the tip of the bar W fed from a bar supplying apparatus
120
to be described next come into contact with the tool.
An NC apparatus
115
of the NC lathe
110
controls travel of the headstock
113
and the tool post
114
in accordance with a machining program.
The bar supplying apparatus
120
for feeding the bar W to the NC lathe
110
is disposed rearward of the NC lathe
110
(in the right part of FIG.
9
).
The bar supplying apparatus
120
has a not-illustrated bar housing for housing a plurality of bars W, a plurality of bar supporting units
128
a
,
128
b
, and
128
c
each for placing the bar W supplied from the bar housing on the main spindle axis C, and run-out preventing chucks
129
a
,
129
b
, and
129
c
provided for the bar supporting units
128
a
,
128
b
, and
128
c
, respectively, each for holding some midpoint of the bar W so that the long bar W is not bent at the time of machining the tip of the bar W. A similar run-out preventing chuck
129
d
is also provided on the rear end side of the main spindle
112
of the NC lathe
110
.
In the rear part of the bar supplying apparatus
120
, a feeder
123
for feeding the bar W placed on the bar supporting units
128
a
,
128
b
, and
128
c
toward the main spindle
112
is provided. At the tip of the feeder
123
, a finger chuck
123
a
which holds the rear end of the bar W and rotates with the bar W is provided.
The feeder
123
is moved forward/backward in the main spindle axis C direction by a driving unit
121
constructed by a motor
121
a
, a pulley
121
b
rotated by the driving of the motor
121
a
, and a belt
121
c
running around the pulley
121
b.
Supply of the bar W from the bar housing, opening/closing of the run-out preventing chucks
129
a
,
129
b
,
129
c
, and
129
d
, and driving of the motor
121
a
are controlled by a control unit
125
provided for the bar supplying apparatus
120
.
In the bar supplying apparatus
120
having the above configuration, it is necessary to prevent interference between the feeder
123
and the run-out preventing chucks
129
a
,
129
b
,
129
c
, and
129
d
at the time of feeding the bar W to the main spindle
112
and during the bar W is machined.
For this purpose, before automatic machining is started, the operator manually feeds the feeder
123
in the main spindle axis C direction to position the tip of the feeder
123
at the position
1
,
2
,
3
, or
4
(refer to
FIG. 9
) before the run-out preventing chuck
129
a
,
129
b
,
129
c
, or
129
d
, respectively. The position of the feeder
123
at this time is stored in the control unit
125
. When the feeder
123
is positioned at the position
1
,
2
,
3
, or
4
, the run-out preventing chuck
129
a
,
129
b
,
129
c
, or
129
d
corresponding to the position is set to be open.
Also, with respect to a timing of cutting the bar W short (which denotes cutting off of the tip portion of the bar having low machine accuracy at the start of machining on the supplied bar) and a timing of replacing the bar W, before the automatic machining is started, the feeder
123
is manually fed so that the tip of the feeder
123
is positioned in the timing position, and the position of the feeder
123
at this time is stored in a memory or the like of the control unit
125
.
The flowchart of
FIG. 10
shows the procedure of the above-described settings.
At the stage of setting before automatic machining is started, setting is started (step S
100
) and, simultaneously, a machining program is loaded to the NC apparatus
115
(step
101
), and the number of products to be machined and the length of a bar are input (steps S
102
and S
103
). A feed torque according to the length and diameter of the bar W is input to the control unit
125
of the bar supplying apparatus
120
(step S
104
).
Subsequently, a timing of opening the run-out preventing chucks
129
a
to
129
d
is input to the control unit
125
(step S
105
). As described above, the timing is input by manually feeding the feeder
123
to any of the positions
1
to
4
and inputting the coordinates of the feeder
123
at this time or the like. The positions
1
to
4
have to be determined in consideration of the maximum stroke of the headstock
113
during machining.
Similarly, the positions of the feeder
123
at the timing of replacing the bar W and timing of cutting the tip short are input to the control unit
125
(step
106
).
Subsequently, data indicating whether the lengths of the bars W housed in the not illustrated bar housing are the same or not is entered (step S
107
).
After completion of the inputting operations, data setting is made, input values are stored in the NC apparatus
115
or the memory in the control unit
125
(step S
108
), and automatic machining is started (step S
109
).
However, in the conventional bar supplying apparatus
120
, the operator has to manually feed the feeder
123
to one of the positions
1
to
4
and enter the coordinates or the like of the feeder
123
in the corresponding position to the control unit
125
. Consequently, the work is troublesome and, moreover, there is a problem that long time is required since the bar W is set initially until the automatic machining starts.
The positions
1
to
4
which are set to prevent interference between the run-out preventing chucks
129
a
to
129
d
and the feeder
123
have to be determined in consideration of the maximum stroke of the headstock
113
at the time of machining the bar W. The operator has to determine the stoke on the basis of the length of a product and the machining program. It is consequently feared that, due to an improper determination, an unexpected situation such that the feeder
123
collides with the run-out preventing chucks
129
a
to
129
d
during machining or at the time of feeding the bar W arises.
The invention has been achieved in consideration of the problems and is to provide a method of controlling a bar supplying apparatus and a numerically controlled lathe which can realize automatic setting of the timing of opening a run-out preventing chuck, the timing of cutting a bar short, and th

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