Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1998-07-02
2001-04-24
Lee, Thomas (Department: 2182)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S086000
Reexamination Certificate
active
06223095
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and a method for generating commands for executing an orientation action of an NC machine tool.
In the present application, the term orientation action is defined as an action for changing the orientation of a workpiece with reference to a tool or the orientation of a tool with reference to a workpiece.
2. Description of the Prior Arts
Until now, when a free-form surface was going to be machined using a five-axis machine tool, an NC program including an interpolation command for an linerotational axis of a tool holding unit and an interpolation command for a workpiece supporting table was first prepared by an automatic programming device together with interpolation commands for linear axes, and then the free-form surface was machined by applying this NC program to an NC control device of the five-axis machine tool.
The above-mentioned automatic programming device generated the interpolation commands for the linear axes and, at the same time, calculated an optimum vector for the surface at each machining point, where the tool came in contact with the surface, on the basis of the generated interpolation commands, and then generated the interpolation commands for the linerotational axis of the tool holding unit and the linerotational axis of the workpiece supporting table so that the tool was always oriented toward the optimum vector at the machining point. Thus the automatic programming device generated an NC program including the interpolation commands for the linear axes and the interpolation commands for the angular motion axes.
As a result, when the obtained NC program has been applied to the NC control device of the five-axis machine tool, the geometrical relationship between the tool and the workpiece surface during machining will exhibit the behavior as shown in FIG.
11
and shown in exaggerated form in FIG.
12
. Both of FIG.
11
and
FIG. 12
show the behavior in the Y-Z plane for convenience.
SUMMARY OF THE INVENTION
In the above-mentioned method, interpolating actions for X, Y, Z linear axes and interpolating actions for angular motion axes of a tool holding unit and a workpiece supporting table should always be executed during machining. Consequently, stiffness of the machine tool is deteriorated. As a result, there are such problems that machining accuracy is lowered, and in addition, this method is not suitable for heavy cutting.
In addition, it is necessary to calculate optimum vectors at every machining point, and interpolation commands for angular motion axes should be prepared so as to cause the tool to be oriented in the direction of the optimum vector. Therefore, complicated calculation should be executed for a tremendously large number of repetitions. Consequently, it takes a long time to prepare an NC program. When it is required to shorten the calculation time, then high performance, that is, expensive automatic programming device is needed.
Objects of the present invention are to generate numerical control commands including orientation commands for angular motion axes so as to carry out heavy cutting and five-axis machining under highly rigid conditions without deteriorating machining accuracy, and in addition, to prepare the above-mentioned orientation commands without executing complicated calculations for a tremendously large number of repetitions by solving the above-mentioned problems.
The objects can be achieved by a numerical control command generating device comprising grouping means for grouping workpiece surfaces to be machined according to inclination of the surfaces on the basis of machining information, angle deciding means for deciding an orientation angle for each of the groups, and command generating means for generating numerical control commands including orientation commands based on the decided orientation angle, wherein the machining information is generated by using any of a shape to be machined, an NC program, and a decoded NC program data decoded from the NC program inside the numerical control device. The numerical control commands are generated by the NC program or the decoded NC program data decoded from the NC program inside the numerical control device, and the grouping means are prepared by comprising dividing means for dividing the workpiece surface, inclination calculating means for calculating inclination of each of the divided workpiece surfaces, and classifying means for classifying the divided workpiece surfaces on the basis of the similarity of the inclination of the divided workpiece surfaces.
In addition, the objects can be achieved in a numerical control command generating device by comprising the steps of a grouping step for grouping workpiece surfaces to be machined according to the inclination of the surfaces on the basis of machining information, an angle deciding step for deciding an orientation angle for each of the groups, and a command generating step for generating numerical control commands including orientation commands based on the decided orientation angle, wherein the grouping step is achieved by comprising the steps of a dividing step for dividing the workpiece surface, an inclination-calculating step for calculating the inclination of each of the divided workpiece surfaces, and a classifying step for classifying the divided workpiece surfaces on the basis of the similarity of the inclination of the divided workpiece surfaces.
In addition, the present invention for achieving the above-mentioned objects comprises media recording a program for making a computer execute a grouping procedure for grouping workpiece surfaces to be machined according to the inclination of the surfaces on the basis of machining information, an angle deciding procedure for deciding an orientation angle for each of the groups, and a command-generating procedure for generating numerical control commands including orientation commands based on the decided orientation angle, wherein the program for executing the grouping procedure comprises a program for executing the dividing procedure for dividing the workpiece surface, a program for executing the inclination-calculating procedure for calculating the inclination of each of the divided workpiece surfaces, and a program for executing a classifying procedure for classifying the divided workpiece surfaces on the basis of the similarity of the inclination.
REFERENCES:
patent: 4998196 (1991-03-01), Seki et al.
patent: 5173648 (1992-12-01), Kawamura et al.
patent: 5704238 (1998-01-01), Tokai
patent: 5828574 (1998-10-01), Robinson et al.
patent: 5930142 (1999-07-01), Schleicher et al.
Fukaya Yasushi
Matsumiya Sadayuki
Morita Naoki
Yamazaki Kazuo
Lee Thomas
Okuma Corporation
Oliff & Berridg,e PLC
Patel Nitin
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