Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Patent
1995-03-07
1996-10-08
Cabeca, John W.
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
318573, 36447434, 36447431, B23B 3926
Patent
active
055634842
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a three-dimensional cutter compensation system for use with a numerically controlled machine tool, and more particularly to a three-dimensional cutter compensation system for use in machining a workpiece with an edge of a cutter having a round tip end while the axis of the cutter is being tilted in any optional direction in a three-dimensional space.
BACKGROUND ART
Numerically controlled machine tools which operate only about X-, Y-, and Z-axes have a cutter axis that is oriented always in a vertical direction, i.e., in any of the axis directions. If two rotational axes are added to such a numerically controlled machine tool, making it a 5-axis numerically controlled machine tool, then the cutter axis may be oriented in any optional direction. For example, a 5-axis diesinking machine can machine a workpiece three-dimensionally with a cutter that can be tilted in any optional direction.
A process of three-dimensionally machining a workpiece with a cutter includes a mode in which the cutter is tilted and the workpiece is machined by an edge of the cutter. In such a mode, a cutter compensation vector is required to be determined as a three-dimensional vector. Heretofore, there have been available different methods of determining a cutter compensation vector as a three-dimensional vector.
According to the first method, an automatic programming apparatus is used to calculate a cutter compensation vector. When the automatic programming apparatus generates a machining program, it simultaneously calculates a cutter compensation vector for automatically determining a cutter path which has been compensated for.
The second method relies upon an NC programmer to calculate the tilt of a cutter, an amount of compensation, and a direction of compensation when a machining program is generated.
The first method which employs an automatic programming apparatus has the following problems: Since the first method needs an automatic programming apparatus at all times, the overall system is expensive. Therefore necessary for the automatic programming apparatus to generate a machining program each time the cutter radius changes.
The second method in which calculations are carried out by an NC programmer is also disadvantageous for the following reasons: When a workpiece surface to be machined varies, i.e., when a curved surface is to be machined, a very large number of calculations is required, and program commands are highly complex, resulting in a large expenditure of time and labor to generate a machining program.
The above methods of determining a cutter compensation vector are also more complex if the cutter has a round edge as with an end mill.
SUMMARY OF THE INVENTION
In view of the aforesaid problems, it is an object of the present invention to provide a three-dimensional cutter compensation system capable of effecting cutter compensation with respect to cutters including a cutter with a round edge, for machining a workpiece with an edge of a cutter while the axis of the cutter is being oriented in any optional direction in three-dimensional space.
To achieve the above object, there is provided a three-dimensional cutter compensation system for use with a numerically controlled machine tool for machining a workpiece with an edge of a cutter while an axis of the cutter is being tilted in any optional direction in three-dimensional space, comprising cutter direction vector calculating means for calculating a cutter direction vector from present positions of a control axes which controls tilt of the cutter, a cutter offset memory for storing a radius of the cutter and a radius of an arc of an edge of the cutter, programmed path calculating means for calculating a programmed path commanded by a machining program, and cutter compensation vector calculating means for calculating a cutter compensation vector from the cutter direction vector calculated by the cutter direction vector calculating means, the radius of the cutter and the radius of the arc of the edge of the cutt
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patent: 5282144 (1994-01-01), Kawamura et al.
Kozai Haruhiko
Ogino Hideo
Otsuki Toshiaki
Cabeca John W.
Fanuc Limited
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