US 6,487,944 B2Granted

Machine tool and control method therefor

AssigneeStar Micronics Co., Ltd.

InventorsNobuyuki Endo, Shigeyuki Kurihara

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Abstract

In cutting a high-accuracy thread, a control unit (CPU) uses a first position data calculation program to determine the moving positions of a workpiece and tool every predetermined rotational angle of a spindle rotating motor. The control unit stores the determined moving positions of the workpiece and tool in a first position data table memory, and outputs the determined moving positions as a workpiece position instruction signal and tool position instruction signal to a workpiece feed control circuit and tool feed control circuit every predetermined rotation. In cutting a low-accuracy thread, the control unit uses a second position data calculation program to determine the moving positions of the workpiece and tool every predetermined time interval. The control unit stores the determined moving positions of the workpiece and tool in a second position data table memory, and outputs the determined moving positions as a workpiece position instruction signal and tool position instruction signal to the workpiece feed control circuit and tool feed control circuit every predetermined time interval.

Claims6

Dependent claims

A machine tool for rotating a workpiece about a predetermined axis, and moving at least one of the workpiece and a tool for machining the workpiece, thereby machining the workpiece into a desired shape, comprising:

pulse signal generation means for generating a pulse signal every predetermined rotational angle at the predetermined axis;
first moving position determination means for determining a moving position of at least one of the workpiece and the tool every predetermined rotational angle;
first movement control means for controlling movement of at least one of the workpiece and the tool in correspondence with the pulse signal generated by said pulse signal generation means so as to set the moving position of at least one of the workpiece and the tool to the moving position determined by said first moving position determination means;
divided-timing signal generation means for generating a divided-timing signal every predetermined time interval;
second moving position determination means for determining the moving position of at least one of the workpiece and the tool every predetermined time interval;
second movement control means for controlling movement of at least one of the workpiece and the tool in correspondence with the divided-timing signal generated by said divided-timing signal generation means so as to set the moving position of at least one of the workpiece and the tool to the moving position determined by said second moving position determination means;
and
control selection means for selecting one of said first and second movement control means to control movement of at least one of the workpiece and the tool.

5 more elements

A control method for a machine tool for rotating a workpiece about a predetermined axis, and moving at least one of the workpiece and a tool for machining the workpiece, thereby machining the workpiece into a desired shape,

the machine tool including:
pulse signal generation means for generating a pulse signal every predetermined rotational angle at the predetermined axis;
first moving position determination means for determining a moving position of at least one of the workpiece and the tool every predetermined rotational angle;
first movement control means for controlling movement of at least one of the workpiece and the tool in correspondence with the pulse signal generated by the pulse signal generation means so as to set the moving position of at least one of the workpiece and the tool to the moving position determined by the first moving position determination means;
divided-timing signal generation means for generating a divided-timing signal every predetermined time interval;
second moving position determination means for determining the moving position of at least one of the workpiece and the tool every predetermined time interval;
and
second movement control means for controlling movement of at least one of the workpiece and the tool in correspondence with the divided-timing signal generated by the divided-timing signal generation means so as to set the moving position of at least one of the workpiece and the tool to the moving position determined by the second moving position determination means, comprising the steps of:
selecting the first movement control means in machining the workpiece at high machining accuracy, and the second movement control means in machining the workpiece at low machining accuracy;
and
decreasing a rotational speed of the workpiece about the predetermined axis in machining the workpiece at the high machining accuracy, and increasing the rotational speed of the workpiece about the predetermined axis in machining the workpiece at the low machining accuracy in comparison with machining the workpiece at the high machining accuracy.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/783,086Filed 15 Feb 2001
Priority: JP 2000-03846016 Feb 2000
Published: US 2001/0013267 A116 Aug 2001
Granted: 3 Dec 2002
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

G05B 19/186
Characterised by the machine tool function, e.g. thread cutting, cam making, tool direction control: generation of screw- or gearlike surfaces
G05B 2219/34341
Director, elements to supervisory: choose between electronic cam or time-dependent as function of required machining accuracy
G05B 2219/36198
Nc in input of data, input key till input tape: gear, thread cutting
G05B 2219/45214
Nc applications: gear cutting