Machine tool control system capable of obtaining workpiece origin and workpiece origin setting method

1. A machine tool control system, comprising:

a machine tool configured to machine an ingot according to a machining program;

an imaging apparatus placed at a predetermined position in the machine tool and configured to take an image of the ingot by a stereo system;

a three-dimensional coordinate computing unit configured to

calculate three-dimensional coordinates of the ingot based on the image of the ingot taken by the imaging apparatus, and

calculate, from the three-dimensional coordinates of the ingot, three-dimensional coordinates of a specified machining start point on the ingot;

a coordinate converting unit configured to

convert the three-dimensional coordinates of the machining start point on the ingot, that are calculated by the three-dimensional coordinate computing unit, into coordinates in a machine coordinate system for the machine tool, and

set the converted three-dimensional coordinates of the machining start point on the ingot, as a workpiece origin, into the machining program for the machine tool;

a touch probe configured to contact each of end faces and a top face of the ingot; and

a workpiece origin updating unit configured to

obtain, in response to the touch probe contacting the ingot, positional coordinates of each of the end faces and the top face of the ingot in the machine coordinate system,

calculate further three-dimensional coordinates of the machining start point on the ingot from the obtained positional coordinates, and

set the further three-dimensional coordinates of the machining start point, as the workpiece origin, into the machining program for the machine tool.

2. The machine tool control system according to claim 1 , further comprising:

a robot having a predetermined relative position to the machine tool, wherein

the imaging apparatus along with a hand configured to grip the ingot is attached to a tip of the robot, and

the robot is configured to place the imaging apparatus at the predetermined position in the machine tool.

3. The machine tool control system according to claim 1 , wherein:

the machine tool comprises an automatic tool changer to which a plurality of machining tools is configured to be attached,

the imaging apparatus is attached to a turret of the automatic tool changer, and

the turret is configured to place the imaging apparatus to the predetermined position in the machine tool.

4. The machine tool control system according to claim 1 , further comprising:

a touch probe motion path generating unit configured to generate a motion path of the touch probe to be brought into contact with each of the end faces and the top face of the ingot, based on the converted three-dimensional coordinates of the ingot obtained by the coordinate converting unit converting the three-dimensional coordinates of the ingot; and

a machine tool control unit configured to cause the machine tool to perform contact motion of the touch probe according to the motion path of the touch probe, the motion path being generated by the touch probe motion path generating unit.

5. A workpiece origin setting method of setting a workpiece origin in a machine tool which machines an ingot according to a machining program, the method comprising:

placing an imaging apparatus at a predetermined position in the machine tool and taking an image of the ingot by a stereo system;

calculating three-dimensional coordinates of the ingot based on the image of the ingot taken by the imaging apparatus, and calculating, from the three-dimensional coordinates of the ingot, three-dimensional coordinates of a specified machining start point on the ingot;

converting the three-dimensional coordinates of the machining start point on the ingot into coordinates in a machine coordinate system for the machine tool;

setting the converted three-dimensional coordinates of the machining start point on the ingot, as a workpiece origin, into the machining program for the machine tool;

converting the three-dimensional coordinates of the ingot into the coordinates in the machine coordinate system for the machine tool;

after setting the workpiece origin, generating a motion path of a touch probe to be brought into contact with each of end faces and a top face of the ingot, based on the converted three-dimensional coordinates in the machine coordinate system for the machine tool;

causing the machine tool to perform contact motion of the touch probe, according to the generated motion path of the touch probe;

obtaining positional coordinates of each of the end faces and the top face of the ingot in the machine coordinate system, in response to the contact motion of the touch probe;

calculating, from the obtained positional coordinates, further three-dimensional coordinates of the machining start point on the ingot; and

setting the further three-dimensional coordinates of the machining start point, as the workpiece origin, into the machining program for the machine tool.

6. A workpiece origin setting method of setting a workpiece origin in a machine tool which machines a workpiece according to a machining program, the method comprising:

placing an imaging apparatus at a predetermined position in the machine tool and taking an image of the workpiece from a plurality of different directions;

calculating three-dimensional coordinates of the workpiece based on a plurality of taken images of the workpiece, and calculating, from the three-dimensional coordinates, three-dimensional coordinates of a specified machining start point on the workpiece;

converting the three-dimensional coordinates of the calculated machining start point on the workpiece into coordinates in a machine coordinate system for the machine tool;

setting the converted three-dimensional coordinates of the machining start point on the workpiece, as a workpiece origin, into the machining program for the machine tool;

converting the three-dimensional coordinates of the workpiece into the coordinates in the machine coordinate system for the machine tool;

rotating, at a predetermined rotation speed, a main spindle to which a machining tool for the machine tool is to be attached;

after setting the workpiece origin, moving the rotating main spindle to each of end faces and a top face of the workpiece, based on the converted three-dimensional coordinates of the workpiece in the machine coordinate system for the machine tool; and

in response to detection of an increase in disturbance torque on the rotating main spindle, the increase being caused by contact of the rotating main spindle with the workpiece,

obtaining positional coordinates of each of the end faces and the top face of the workpiece in the machine coordinate system,

calculating, from the obtained positional coordinates, further three-dimensional coordinates of the machining start point on the workpiece, and

setting the further three-dimensional coordinates of the machining start point, as the workpiece origin, into the machining program for the machine tool.

7. The machine tool control system according to claim 1 , wherein the three-dimensional coordinate computing unit is configured to obtain the three-dimensional coordinates of the machining start point on the ingot based on image data of the ingot from the imaging apparatus.