JP2009230552A - Numerical control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a moving route of a movable shaft which obtains the same working shape as when there is no installation error of a workpiece while suppressing the speed of the movable shaft of a machine tool from being excessively increased while keeping the moving route of the movable shaft within the movable range of the movable shaft of the machine tool even when there is an installation error of the workpiece. <P>SOLUTION: A singular point neighborhood passing determining part 2 determines whether a route of a tool direction specified by corrected coordinates pass near a singular point when correcting the rotating shaft angle of each coordinate between start coordinates and end coordinates according to a correction parameter 7. A corrected start and end coordinate operating part 3 operates corrected end coordinates of an installation error of the workpiece on the basis of a singular point neighborhood passing determination result and the correction parameter 7. An interpolation method determining part 4 determines an interpolation method between the start coordinates and the end coordinates on the basis of a determination result of the singular point neighborhood passing determining part 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a numerical control device for numerically controlling a machine tool (Numerical Control: NC), and more particularly to a numerical control device for controlling a machine tool having a rotating shaft in addition to a linear motion shaft.

When machining a workpiece with a machine tool, even if the workpiece is placed at a position and orientation different from the machining workpiece installation position assumed when creating the machining program, it is the same as when machining with the correct installation position. The command value may be corrected by the numerical control device so that it can be processed into a shape.
In particular, in a machine tool having a rotation axis in addition to the X, Y, and Z linear motion axes, the direction of the tool relative to the workpiece is also corrected. In this correction, the direction of the tool viewed from the workpiece (hereinafter referred to as the tool direction) is obtained from the commanded rotation axis angle, and the machining workpiece installation error is corrected for this tool direction. This is realized by obtaining a rotation axis angle such that the tool is directed in the tool direction after the minute correction is performed (for example, Patent Document 1).

JP 7-299697 A

However, according to the above conventional technique, in order to correct the orientation of the tool with respect to the workpiece, the rotation axis angle is obtained from the tool direction. However, in general, the rotation axis angle cannot be uniquely obtained. . That is, there are two or more rotation axis angles at which the tool can be directed in the designated tool direction.
For example, consider a 5-axis machine in which a rotary table that rotates around the Z axis is connected to a tilt table that rotates around the X axis, and the rotation axis around the X axis is the rotation around the A axis and the Z axis. Let the axis be the C-axis. In this case, the direction of the tool when the A-axis is 45 ° and the C-axis is 0 ° and the direction of the tool when the A-axis is −45 ° and the C-axis are 180 ° are exactly the same when viewed from the workpiece attached to the table. Direction. If the A axis is 0 °, the direction of the tool viewed from the workpiece is exactly the same regardless of the angle of the C axis.
Therefore, in the conventional numerical control device, the angle closest to the angle immediately before moving (the angle at the previous interpolation point) is selected, but if the movable range of the rotation axis of the machine tool is limited, the rotation axis is corrected. There was a problem that the later angle could not be reached.
Also, if the tool direction is in the vicinity of a singular point (the point where the tool direction coincides with the axis direction of the rotation axis, in the above example, the A axis is 0 ° or 180 °), the rotation axis before correction The change in the angle of the rotation axis after correction may become extremely large compared to the change in the angle of the machine, and by correcting the angle of the rotation axis, the speed of each axis of the machine tool may become excessive. There was a problem.

  The present invention has been made in view of the above. Even when there is an installation error of a workpiece, the moving path of the movable shaft is within the movable range of the movable shaft of the machine tool, and An object of the present invention is to obtain a numerical control device capable of realizing a path of a movable axis that can obtain the same machining shape as when there is no installation error of a workpiece while suppressing an excessive speed of the movable axis. .

  In order to solve the above-described problems and achieve the object, the present invention corrects a workpiece installation error according to a preset correction parameter, and determines the position of each axis of a machine tool including a linear motion axis and a rotation axis, and In a numerical control device that controls the angle, a program analysis unit that analyzes a machining program and outputs a start point coordinate and an end point coordinate before correction of the machining workpiece installation error based on the analysis result, and a start point before the correction A singular point vicinity passage determination unit that determines whether or not a path of the coordinate after correcting the installation error of the workpiece passes through the vicinity of a singular point based on the coordinates and end point coordinates and the correction parameter, and the vicinity of the singular point Based on the determination result by the passage determination unit and the correction parameter, the corrected start / end point coordinate calculation unit that calculates the corrected start point coordinate and end point coordinate, and the singularity An interpolation method determining unit that determines an interpolation method between the start point coordinates and the end point coordinates based on a determination result by a proximity pass determination unit, the start point coordinates and end point coordinates before correction, and the start point coordinates after correction and Performing interpolation between the start point coordinates and the end point coordinates based on the end point coordinates, the interpolation method, and the correction parameter, and correcting the machining workpiece installation error at the interpolation points, thereby interpolating the points. And an interpolation calculation unit for outputting the linear motion axis position and the rotation axis angle after correction of the installation error of the workpiece.

  According to the present invention, even when there is an installation error of the workpiece, the speed of the movable shaft of the machine tool becomes excessive after the moving path of the movable shaft is within the movable range of the movable shaft of the machine tool. While suppressing the above, there is an effect that it is possible to realize the path of the movable shaft that can obtain the same machining shape as when there is no installation error of the workpiece.

  Embodiments of a numerical controller according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a numerical control apparatus according to the present invention.
In FIG. 1, a numerical control device 10 corrects a correction value of a workpiece installation error according to a preset correction parameter 7 and controls the position and angle of each axis of a machine tool including a linear motion axis and a rotation axis. be able to. The correction parameter 7 can specify an installation error (translation component error, rotation component error) of the workpiece.
Here, the numerical controller 10 indicates that the tool direction path specified by the corrected coordinates when the correction is performed so as to obtain the same machining shape as when there is no machining workpiece installation error is near the singular point. Can be determined. Note that the singular point is a point where the tool direction and the axial direction of any one of the rotating shafts coincide with each other. This refers to the direction in which the tool direction seen from the workpiece is exactly the same.

Then, based on the determination result as to whether or not it passes through the vicinity of the singular point, the path of the linear motion axis and the rotational axis can be selected from the candidates for the path of the linear motion axis and the rotational axis. For example, when the path of the rotation axis passes in the vicinity of the singular point, the angle of the rotation axis at the command end point is within the movable range, and the rotation axis so that the amount of angular movement of the rotation axis in the vicinity of the singular point is minimized. The route can be selected.
Specifically, the numerical control device 10 includes a program analysis unit 1 that analyzes a machining program, and whether or not a tool direction path specified by coordinates after correction of a machining workpiece installation error passes near a singular point. Singularity point vicinity passage determination unit 2 to determine, based on the singularity point vicinity passage determination result, corrected start and end point coordinate calculation unit 3 that calculates the corrected start point coordinates and end point coordinates of the workpiece installation error, the start point coordinates and the above Interpolation method determining unit 4 for determining an interpolation method between the end point coordinates and an interpolation operation for outputting a linear motion axis position and a rotation axis angle after correcting a work workpiece installation error at an interpolation point between the start point coordinates and the end point coordinates. Part 5 is provided.

In the following description, the coordinates before correction of the machining workpiece setting error set in the correction parameter 7 are referred to as coordinates before correction (linear motion axis position / rotation axis angle), and the machining workpiece installation error is corrected. The coordinates after correction is referred to as corrected coordinates (linear motion axis position / rotation axis angle).
The machining program 6 is input to the program analysis unit 1, and the correction parameter 7 is input to the singular point vicinity passage determination unit 2, the corrected start / end point coordinate calculation unit 3, and the interpolation calculation unit 5.
Then, the program analysis unit 1 analyzes the machining program 6 and determines the start point coordinates (linear motion axis position / rotation axis angle) and end point coordinates (linear motion axis position / rotation axis angle) of the path instructed by the machining program 6. It outputs to the singularity vicinity passage determination unit 2. Then, the singular point vicinity passage determination unit 2 determines that the path in the tool direction specified by the corrected coordinates when the rotation axis angle of each coordinate between the start point coordinates and the end point coordinates is corrected according to the correction parameter 7 is the singular point. It is determined whether or not the vehicle passes through the vicinity, and the singular point vicinity pass determination result is output to the corrected start / end coordinate calculation unit 3. Then, the corrected start / end point coordinate calculation unit 3 calculates the corrected end point coordinates (linear motion axis position / rotation axis angle) of the workpiece installation error based on the singular point vicinity passage determination result and the correction parameter 7. And output to the interpolation calculation unit 5.

  On the other hand, the interpolation method determination unit 4 determines an interpolation method between the start point coordinates and the end point coordinates based on the determination result of the singular point neighboring passage determination unit 2 and outputs the interpolation method to the interpolation calculation unit 5. Then, the interpolation calculation unit 5 performs an interpolation method from the start point coordinates and end point coordinates before correction output from the program analysis unit 1 and the corrected start point coordinates and end point coordinates output from the corrected start / end point coordinate calculation unit 3. In accordance with the interpolation method and the correction parameter 7 designated by the determination unit 4, the linear motion axis position and the rotational axis angle after correction of the machining workpiece installation error at the interpolation point are calculated and output to the servo controller 9. Then, the servo control device 9 performs servo control so that each axis of the machine is driven according to the linear motion axis position and the rotation axis angle output from the interpolation calculation unit 5.

  Thereby, the path | route of each axis | shaft after the correction | amendment of the installation error of a workpiece can be set, considering whether it passes the vicinity of a singular point. For this reason, even if there is an installation error of the workpiece, it is possible to process into the same shape as when there is no installation error of the workpiece, while keeping the movement path of the movable axis out of the movable range. It becomes possible to set the coordinates of the end point, and it is possible to suppress the rapid movement of the axis due to the excessive movement speed of each axis even near the singular point.

  Hereinafter, the operation of the present embodiment will be described in detail. In the following description, for the sake of brevity, the machine to be controlled is a 5-axis processing machine in which a rotary table rotating around the Z axis is connected to an inclined table rotating around the X axis. The rotation axis around the X axis is the A axis, and the rotation axis around the Z axis is the C axis. This type of machine is called an AC table rotary type 5-axis machine.

FIG. 10 is a diagram schematically showing an AC table rotary type five-axis machine that is numerically controlled by the numerical controller of FIG.
In FIG. 10, the AC table rotary type 5-axis processing machine is provided with an A-axis tilt table 22 and a C-axis tilt table 23 with respect to the main shaft 21, and the A-axis tilt table 22 can rotate around the X axis. The C-axis rotary table 23 can rotate around the Z-axis on the A-axis tilt table 22.
In FIG. 1, the program analysis unit 1 reads an axis movement command in the machining program, creates a start point coordinate and an end point coordinate before correction for each movement command, a singular point neighboring passage determination unit 2 and an interpolation calculation unit 5. Output to.

Then, the singular point vicinity passage determination unit 2 determines that the path in the tool direction specified by the corrected coordinates when the rotation axis angle of each coordinate between the start point coordinates and the end point coordinates is corrected according to the correction parameter 7 is the singular point. Judge whether it passes through the neighborhood. In the AC table rotary type 5-axis machine shown in FIG. 10, the state where the A axis is 0 ° or 180 ° is a singular point.
Hereinafter, a method for determining the passage around the singular point will be described.
First, when the machining workpiece installation error is corrected according to the correction parameter 7, an angle before correction, which becomes a singular point, is obtained. This angle is called an angle before singular point correction. In the AC table rotating type 5-axis machining apparatus, it can be obtained as follows. If the singular point pre-correction angles are A _sg and C _sg , the following equation (1) is established.

ここで、Ｒ_ｅｒｒは姿勢誤差行列であり、加工ワークの設置誤差のうち、回転成分誤差（姿勢に関する誤差）を定義するための３行３列の回転行列であり、補正パラメータ７から求めることができる。すなわち、補正パラメータ７の回転成分誤差がロール角θ_Ｒ、ピッチ角θ_Ｐ、ヨー角θ_Ｙで表される場合、姿勢誤差行列Ｒ_ｅｒｒは以下の式で求めることができる。

Here, R _err is an attitude error matrix, which is a 3-by-3 rotation matrix for defining a rotation component error (an error related to the attitude) among the workpiece installation errors, and can be obtained from the correction parameter 7. it can. That is, when the rotation component error of the correction parameter 7 is expressed by the roll angle θ _R , the pitch angle θ _P , and the yaw angle θ _Y , the attitude error matrix R _err can be obtained by the following equation.

従って、特異点補正前角度Ａ_ｓｇ、Ｃ_ｓｇについて（１）式を解けば、特異点補正前角度Ａ_ｓｇ、Ｃ_ｓｇを求めることができる。なお、（１）式は一般に複数組の解を持つので、始点回転軸角度と終点回転軸角度の間にあるすべての解の組を求める。

Therefore, the singularity uncorrected angle _{A sg,} Solving for _{C sg} (1) formula, singularity uncorrected angle _{A sg,} can be obtained _{C sg.} Since equation (1) generally has a plurality of sets of solutions, all solution sets between the start point rotation axis angle and the end point rotation axis angle are obtained.

Next, when the singular point vicinity passage determination unit 2 finds the singular point pre-correction angle, it determines whether the path interpolated between the start point rotation axis angle and the end point rotation axis angle passes near the singular point correction angle. judge. Normally, linear interpolation is performed between the commanded start point rotation axis angle and end point rotation axis angle, so that the coordinate values of the two rotation axes are expressed as points in a two-dimensional plane where each coordinate axis represents the coordinates of each rotation axis. If the distance between the straight line connecting the start point rotation axis angle and the end point rotation axis angle and the point before the singular point correction is geometrically determined, and if the distance is smaller than a preset threshold, It is determined that the path in the tool direction specified by the coordinates passes near the singular point, and if it is larger than the threshold value, it can be determined that the tool does not pass near the singular point. This determination is characterized in that the determination can be made without performing the interpolation calculation of the start point coordinates and the end point coordinates and the interpolation calculation of the machining work installation error with respect to the interpolation point coordinates.
In addition, when the tool direction path specified by the corrected coordinates passes near the singular point, the original section that is commanded to move is divided into small sections at the point that passes the boundary near the singular point. Then, start point coordinates and end point coordinates before correction in each small section are obtained. Further, information is set for each small section as to whether it is near a singular point or not near a singular point.
Next, the post-correction start / end point coordinate calculation unit 3 is based on the determination result by the singular point vicinity pass determination unit 2 and the correction parameter 7, and the start point / end point coordinates (direct (Dynamic axis position / rotation axis angle) is calculated.

FIG. 2 is a flowchart showing the operation of the corrected start / end point coordinate calculation unit 3 of FIG.
In FIG. 2, in step S1, candidates for the corrected end point rotation axis angle are obtained from the end point rotation axis angle before correction. This calculation can be performed as follows in the case of the AC table rotary type five-axis processing machine of FIG.
That is, if the end point rotation axis angles before correction are A _ref and C _ref and the end point rotation axis angles after correction are A _comp and C _comp , the following equation (3) is established.

この（３）式を補正後の終点回転軸角度Ａ_ｃｏｍｐ、Ｃ_ｃｏｍｐについて解けば、補正後の終点回転軸角度Ａ_ｃｏｍｐ、Ｃ_ｃｏｍｐを求めることができる。ただし、（３）式は一般に複数の解を持つので、これらの解をすべて補正後の終点回転軸角度の候補とする。

By solving the equation (3) for the corrected end point rotation axis angles A _comp and C _comp , the corrected end point rotation axis angles A _comp and C _comp can be obtained. However, since equation (3) generally has a plurality of solutions, all these solutions are candidates for the corrected end-point rotation axis angle.

  Next, in step S <b> 2, it is determined whether or not each small section is set to be in the vicinity of the singular point in the singular point vicinity passage determination unit 2. Then, the corrected initial start / end point coordinate calculation unit 3 determines that the small section determined not to be in the vicinity of the singular point is a plurality of corrected end point rotation axis angle candidates after correction of the small section in step S5. Candidates in the same solution area as the starting point rotation axis angle are selected as corrected end point rotation axis angles. The solution region is defined as a solution region having a singular point as a boundary. For example, in the case of the AC table rotating type 5-axis processing machine shown in FIG. 10, the angle of the A-axis is a solution area with 0 ° and 180 ° as boundaries.

On the other hand, in the small section determined to be close to the singular point by the singular point vicinity passage determination unit 2, the corrected angle of the command end point is out of the movable range from a plurality of corrected end point rotation axis angle candidates in step S3. Are excluded. Here, by excluding candidates for which the corrected angle of the command end point is outside the movable range, the coordinates of the corrected end point do not fall outside the movable range of the processing machine when passing near the singular point. It becomes possible to set the end point coordinates.
Thereafter, in step S4, an end point rotation axis angle candidate is selected from the remaining candidates so that the amount of movement of the rotation axis angle in the region near the singular point is minimized.
Here, the singular point vicinity passage determination unit 2 divides the commanded section into small sections divided into a singular point vicinity part and a non-singular point vicinity part when passing near the singular point, and calculates corrected start and end point coordinates. The unit 3 can calculate the end point rotation axis angle at the time of passing near the singular point before performing interpolation by calculating the corrected end point coordinates for each small section. It can be determined in advance whether or not the movable range is exceeded.

Next, in step S6, the corrected end point linear motion axis position is obtained. That is, the commanded position is once converted into a coordinate system viewed from the workpiece, the converted coordinate value is multiplied by the posture error matrix R _err of the machining workpiece installation error, and the translation component of the installation error amount is added. By performing coordinate conversion to the coordinate system seen from the machine, the corrected end point linear motion axis position can be obtained. Further, the start point coordinates of each small section can be obtained by substituting the end point coordinates of the previous small section.

Next, the interpolation method determination unit 4 determines a rotation axis angle interpolation method for each small section based on the determination result in the singular point vicinity passage determination unit 2. Determination of the rotation axis angle interpolation method is performed as follows. That is, in the small section where the tool direction is in the vicinity of the singular point, the corrected rotation axis angle is linearly interpolated. On the other hand, in the small section where the tool direction is not near the singular point, the rotation axis angle before correction is linearly interpolated. Here, when the tool direction is in the vicinity of the singular point, the interpolation method determination unit 4 interpolates the corrected rotation axis angle, so that the coordinate value changes abruptly in the vicinity of the singular point and each axis is changed. It is possible to prevent the movement speed from becoming excessive.
Next, the interpolation calculation unit 5 interpolates between the start point coordinates and end point coordinates of each small section, and calculates the corrected linear motion axis position and rotation axis angle based on the correction parameter 7 for each interpolation point.

FIG. 3 is a flowchart showing the operation of the interpolation calculation unit 5 of FIG.
3, in step S11, it is determined whether the interpolation method of the rotation axis angle is the interpolation before correction or the interpolation after correction, and the interpolation method determination unit 4 in FIG. 1 performs linear interpolation on the rotation axis angle after correction. In the set section, the correction at the interpolation point is performed by linearly interpolating between the corrected start point rotation axis angle and end point rotation axis angle obtained in the corrected start / end point coordinate calculation unit 3 in step S14. The later rotation axis angle is obtained. Here, in the case of the vicinity of the singular point, by interpolating the corrected coordinates, it is possible to prevent the coordinate value from changing suddenly in the vicinity of the singular point and the movement speed of each axis from becoming excessive.

On the other hand, in the section set by the interpolation method determination unit 4 so as to linearly interpolate the rotation axis angle before correction, linear interpolation is performed between the start point rotation axis angle and end point rotation axis angle before correction in step S12. Thus, the rotation axis angle before correction at the interpolation point is obtained.
Further, in step S13, an angle after correction of the machining workpiece installation error at the interpolation point, that is, an angle after correction at the interpolation point is obtained. This calculation can be performed by the same method as the calculation of the end point rotation axis angle.
For example, in the case of an AC table rotary type 5-axis processing machine, it can be obtained by using equation (3). However, in this case, a candidate of the same solution area as the starting point of the small section is selected.
After the corrected rotation axis angle at the interpolation point is obtained by the above steps, the corrected linear motion axis position at each interpolation point is obtained in steps S15 and S16.

That is, in step S15, the linear motion axis position before correction at the interpolation point is obtained by performing linear interpolation between the start point linear motion axis position and the end point linear motion shaft position before correction.
Next, in step S16, a linear motion axis position after correction for the linear motion axis position of the interpolation point is obtained. The linear motion axis position after correction of this interpolation point can be obtained in the same manner as the calculation of the end linear motion axis position. In other words, the linear motion axis position of the interpolation point is once converted into a coordinate system viewed from the workpiece, the post-conversion coordinate value is multiplied by the posture error matrix R _err of the workpiece installation error, and the translation component of the installation error amount is added. Further, it can be obtained by converting the coordinates into a coordinate system viewed from the machine.

Next, a specific operation example in this embodiment will be described. Consider the case where the following angle command is issued in the AC table rotary type 5-axis machining apparatus of FIG.
Start point: (A, C) = (30 °, 210 °)
End point: (A, C) = (30 °, 60 °)
Speed: 600 ° / min In addition, the C-axis of this processing machine can be rotated without any limitation of the movable range, but the A-axis is limited to a range of −90 ° to 40 °. .

FIG. 4 is a diagram illustrating an example of a change in rotation axis angle when there is no installation error of the workpiece.
In FIG. 4, when the workpiece is set without installation error, the A axis does not move because the start point and the end point are the same, and the C axis moves from 210 ° to 60 ° at a constant speed.

FIG. 5 is a diagram illustrating an example of a change in the tool direction as viewed from the machining workpiece when there is no installation error of the machining workpiece.
In FIG. 5, the A axis remains 30 ° and only the C axis rotates from 210 ° to 60 °. For this reason, the tool direction viewed from the workpiece passes through a path along the side surface of the cone having a half apex angle of 30 ° between the start point P1 and the end point P2.
Next, let us consider correcting the machining work installation error when the workpiece is placed at an angle of 30.1 ° around the X axis. The installation error, expressed in roll, pitch and yaw angle, the roll angle theta _R is 30.1 °, corresponds to the case both the pitch angle theta _P and the yaw angle theta _Y of 0 °.

FIG. 6 is a diagram illustrating an example of a change in the corrected rotation axis angle corrected using the conventional technique when there is an installation error of the workpiece. It is assumed that the A axis is in the range of (0 ° <A <180 °) before the start of the command.
In FIG. 6, when the rotation axis angle is corrected by the conventional technique so that the tool direction viewed from the machining workpiece passes through the same path as when there is no machining workpiece installation error, the corrected angle starts at (A, C ) = (14.9 °, −76.6 °), and the end point is (A, C) = (51.4 °, 33.6 °).

However, since the movable range of the A axis is limited between −90 ° and 40 °, in this case, the A axis cannot reach the end point. Even if there is no limitation on the movable range of the A axis, the angle of the C axis changes abruptly when the A axis is near 0 °, and the maximum speed that can be realized by the servo controller 9 is reached. It may exceed.
Next, the operation when this embodiment is used will be described.
In this case, an angle before singular point correction is obtained in order to perform a singular point vicinity passage determination. For the angle before singular point correction, the following four combinations can be obtained using equation (1). That is, (A, C) = (30.1 °, 180 °), (−30.1 °, 0 °), (−149.9 °, 180 °), (149.9 °, 0 °) There are four ways. Here, for example, a region where the difference from the angle before singular point correction is 5 ° or less for both the A axis and the C axis is defined as a singular point vicinity region.

FIG. 7 is a diagram for explaining a singular point vicinity passage determination method in the singular point vicinity passage determination unit 2 of FIG.
In FIG. 7, (A, C) = (30.1 °, 180 °), (-30.1 °, 0 °), (-149.9 °, 180 °), (149.9 °, 0 ° ), Four singularity neighboring regions R2, R3, R1, and R4 are obtained respectively.
The path of the angle before correction passes in the vicinity of (A, C) = (30.5 °, 180 °), and the path obtained by linear interpolation between the start point P1 and the end point P2 before correction is a singular point. It can be seen that it passes through the neighborhood region R2. Therefore, as shown below, the command section is divided into three small sections before and after the singular point vicinity region R2.
First small section: Start point (A, C) = (30 °, 210 °)
End point (A, C) = (30 °, 185 °)
Second small section: Start point (A, C) = (30 °, 185 °)
End point (A, C) = (30 °, 175 °)
Third small section: Start point (A, C) = (30 °, 175 °)
End point (A, C) = (30 °, 60 °)

Next, in each subsection, the corrected end point rotation axis angle is calculated. Each candidate of the corrected end-point rotation axis angle is obtained using equation (1), and selected from a plurality of candidates by the procedure shown in FIG.
Since the first small section is not near the singular point, the corrected end point angle is a candidate for the same solution region (0 ° <A <180 °) as the start point (A, C) = (2.4 °, −85. 5 °). Since the second small section is near the singular point, an angle is selected so that the command end point is within the movable range of each axis. As a result, (A, C) = (− 2.8 °, −94.5 °). Since the third small section is not near the singular point, it is an angle (A, C) = (− 51 °, −146) that is the same solution region (−180 ° <A <0 °) as the start point of the third small section. °).
The interpolation method interpolates the angle before correction because the first small section and the third small section are not near the singular point, and the corrected angle is interpolated because the second small section is near the singular point.

FIG. 8 is an example of the corrected rotation axis angle change corrected using the present embodiment when there is an installation error of the workpiece.
In FIG. 8, it can be seen that the corrected rotation axis angle changes within the movable range, and there is no sudden change in the rotation axis angle.

FIG. 9 is a diagram illustrating an example of a change in the tool direction viewed from the machining workpiece when there is an installation error of the machining workpiece.
In FIG. 9, the route is the same as the route when there is no machining workpiece installation error (FIG. 5), and the same machining shape as the machining shape when there is no machining workpiece installation error even if there is a machining workpiece installation error. It can be seen that
As described above, by using the numerical control device described in the present invention, even when there is a machining work installation error, the same shape as when there is no machining work installation error can be machined, and the manufacturing yield is improved. Therefore, it is possible to reduce the environmental load in the machining process. In addition, even if the movement range of each axis is limited, the coordinates of the end point can be set so as not to be outside the movement range, and in addition, the axis movement speed is excessive even near the singular point, causing rapid axis movement This can be prevented and a long life of the machine tool can be achieved.

In the present embodiment, the AC table rotating type 5-axis processing machine has been described. However, a 5-axis processing machine having a different shaft configuration of the rotating shaft may be used. That is, it may be a machine having a biaxial rotating part on the tool side, or a machine having a rotating part on each of the tool side and the table side.
In the present embodiment, in the small section near the singular point, the interpolation calculation unit 5 linearly interpolates the corrected angle of only the rotation axis angle among the coordinates of the start point and end point. You may make it linearly interpolate the rotation axis angle and linear motion axis position after correction | amendment about both an angle and a linear motion axis position. By doing in this way, the calculation of the workpiece installation error correction about the linear motion axis position in the small section near the singular point can be omitted.
Further, in the present embodiment, the correction parameter 7 is given independently of the machining program 6, but may be recorded in advance on the machining program 6. In this case, a portion corresponding to the correction parameter 7 may be read from the machining program 6 and used as the correction parameter 7.

  As described above, the numerical control device according to the present invention can obtain the same machining shape as when there is no machining work installation error without imposing an excessive load on the machine tool even when there is a machining work installation error. Thus, it is suitable for a method of numerically controlling a machine tool.

It is a block diagram which shows schematic structure of embodiment of the numerical control apparatus which concerns on this invention. It is a flowchart which shows operation | movement of the after-correction start / end point coordinate calculating part 3 of FIG. It is a flowchart which shows operation | movement of the interpolation calculating part 5 of FIG. It is a figure which shows an example of a rotating shaft angle change when there is no installation error of a workpiece. It is a figure which shows an example of the change of the tool direction seen from the process workpiece when there is no installation error of a process workpiece. It is a figure which shows an example of the change of the rotation axis angle after correction | amendment correct | amended using the prior art when there exists an installation error of a workpiece. It is a figure explaining the singular point vicinity passage determination method in the singular point vicinity passage determination part 2 of FIG. It is a figure which shows the example of the rotation axis angle change after correction | amendment correct | amended using this Embodiment when there exists an installation error of a workpiece. It is a figure which shows an example of the change of the tool direction seen from the workpiece | work when there exists an installation error of a workpiece | work. It is a figure which shows typically the AC table rotary type 5 axis | shaft processing machine numerically controlled by the numerical control apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Program analysis part 2 Singularity vicinity passage determination part 3 After correction | amendment start / end point coordinate calculation part 4 Interpolation method determination part 5 Interpolation calculation part 6 Machining program 7 Correction parameter 9 Servo control apparatus 10 Numerical control apparatus 21 Spindle 22 A-axis inclination table 23 C-axis rotary table

Claims (4)

In a numerical control device that corrects an installation error of a workpiece according to a preset correction parameter and controls the position and angle of each axis of a machine tool including a linear motion axis and a rotation axis,
Analyzing a machining program, and based on the analysis result, a program analysis unit that outputs start point coordinates and end point coordinates before correction of the machining workpiece installation error;
A singular point vicinity passage determination unit that determines whether or not a path of coordinates after correction of the installation error of the workpiece passes through the vicinity of a singular point based on the start point coordinates and end point coordinates before correction and the correction parameter; ,
Based on a determination result by the singular point vicinity passage determination unit and the correction parameter, a corrected start / end coordinate calculation unit that calculates the corrected start point coordinate and end point coordinate,
An interpolation method determining unit that determines an interpolation method between the start point coordinates and the end point coordinates based on a determination result by the singular point vicinity passage determination unit;
Based on the start point coordinates and end point coordinates before correction, the corrected start point coordinates and end point coordinates, the interpolation method, and the correction parameters, interpolation is performed between the start point coordinates and the end point coordinates, and the processing A numerical value, comprising: an interpolation calculation unit that outputs a linear motion axis position and a rotation axis angle after correction of the installation error of the processed workpiece at the interpolation point by correcting the workpiece installation error at the interpolation point. Control device. The singular point vicinity passage determination unit, when it is determined that the route passes through the vicinity of the singular point, divides the commanded section into small sections divided into a singular point vicinity part and a non-singular point vicinity part,
The numerical control apparatus according to claim 1, wherein the corrected start / end point coordinate calculation unit calculates a start point coordinate and an end point coordinate after correction of an installation error of the workpiece for each small section.   The corrected start / end point coordinate calculation unit, if the small section is in the vicinity of a singular point, the coordinate at the end point of the commanded section is within the movable range of the machine tool from a plurality of corrected end point coordinate candidates. The numerical control device according to claim 2, wherein the end point coordinates are selected so as to fall within the range. The interpolation method determining unit interpolates the corrected rotation axis angle in a small section near a singular point, and interpolates the rotation axis angle before the correction in a small section not in the vicinity of a singular point. Decide
When interpolating the rotation axis angle before correction, the interpolation calculation unit processes the interpolation point obtained by interpolation between the start point rotation axis angle and the end point rotation axis angle before correction of the small section. When the rotation axis angle obtained by correcting the workpiece installation error is output and the corrected rotation axis angle is interpolated, the correction is made between the corrected start point rotation axis angle and end point rotation axis angle of the small section. 4. The numerical control apparatus according to claim 2, wherein the rotation axis angle after correction at the interpolation point obtained by the interpolation is output.

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