JP4038185B2 - Numerical control method - Google Patents

Description

The present invention relates to a numerical control method of controlling a machine having a rotating shaft in addition to the linear movement axis.

  As a machine tool for machining a free-form surface such as a mold, a machine having a rotation axis in addition to a linear movement axis is used. A 5-axis machine tool having X, Y, and Z linear movement axes and two rotation axes is known. Since the rotary shafts are provided, the tool can be arbitrarily tilted with respect to the workpiece processing surface of the workpiece as the rotary shafts rotate. Since the tool length correction amount changes as the tool tilts, machining is performed while correcting the tool length (see, for example, Patent Document 1 and Patent Document 2).

  Further, in a 5-axis machine tool including a linear movement axis of X, Y, and Z, a C axis of a rotation axis around a vertical axis, and a member that rotates about a B ′ axis inclined by a predetermined angle with respect to the C axis, In order to correct the tilt error from the vertical axis of the shaft, the tilt angle error of the B ′ axis, and the error of the rotation center position of the B ′ and C axes, the B ′ axis is fixed at a predetermined angle and rotated around the C axis. The spindle tip position for each predetermined turning angle is measured, multiple regression analysis is performed from the regression data from the measurement data to obtain the turning plane, the axial direction vector of the C axis member is obtained, the C axis is fixed at the predetermined angle, Rotate around the B axis and measure the spindle tip position for each predetermined turning angle. From this measurement data, multiple regression analysis is performed from the regression equation to obtain the turning plane to obtain the axis direction vector of the B axis member. Find the spindle tip position when swiveling around the axis. The difference between the spindle tip position and the spindle position when there is no error is taken as the spindle head position error, the sign of the spindle head position error is inverted to obtain a correction value, and the NC program coordinate system is offset to correct the spindle head error. What was made is known (refer patent document 3).

Japanese Patent Laid-Open No. 3-109606 Japanese Patent Laid-Open No. 5-100723 JP 2001-269839 A

  In the above-described tool length correction methods of Patent Documents 1 and 2, a shift or inclination of the rotation axis center is not taken into consideration. When the rotation axis center deviates or tilts from the original position (when there is an error in the rotation center axis and its direction recognized by the control system executing the machining program and the rotation center axis and its direction) Not considered. Further, even when the main spindle turning center is deviated or inclined from the original position, no consideration is given.

  However, in manufacturing the machine tool, it is difficult to accurately manufacture the rotation axis center in the original position and direction and the spindle turning center in the original position and direction, and an error occurs. In Patent Document 3 described above, the spindle head position error correction is performed in consideration of the center position error and the tilt error of the rotation axis. This method, however, fixes one of the two rotation axes and the other is a predetermined one. Based on the data obtained by measuring the spindle tip position for each angle rotated position, multiple regression analysis is performed from the regression equation to obtain the turning plane to obtain the axial direction vector, and further, the axial direction vector is rotated. In this state, the spindle tip position is obtained, the difference from the original spindle position is set as the spindle head position error, and the NC coordinate system is offset corresponding to the spindle head position error, and the processing is complicated.

Furthermore, the method described in Patent Document 3 has the following problems.
For each positioning of the two rotating shafts, the rotating shafts are rotated by a predetermined angle and measured, and the actual direction vector of these rotating shafts is obtained. Therefore, there is a problem that it takes time for measurement every time the rotary shaft is positioned, and a problem that it cannot be used for continuous machining including the movement of the rotary shaft. Further, it is assumed that the rotation centers of the two rotation shafts cross each other, and the case where there is a divergence between the two rotation centers is not considered. Furthermore, there is a problem that an error between the spindle rotation center and the rotation axis is not considered.

Therefore, an object of the present invention is to provide a numerical control method for controlling a machine including a rotating shaft when the center of the rotating shaft is deviated or inclined from the original position, or when the spindle turning center is deviated or inclined from the original position. in case it is also to provide a numerical control method which can easily and highly accurate machining, and including the movement of the rotary shaft continuous processing.

The invention according to claim 1 of the present application is a numerical control method by a numerical control device for a machine having a linear movement axis, a first rotation axis for rotating a tool head, and a second rotation axis on the first rotation axis,
An actual tool length vector V3 in which the tool length vector is corrected by a conversion matrix based on a deviation position between the spindle center of rotation without a mechanical error and the actual spindle center of rotation is obtained.
The actual tool length vector V3 is rotated by a command for the second rotation axis by a conversion matrix based on a reference position free from a mechanical error of the second rotation axis, an actual rotation axis shift amount, and a command position to the second rotation axis. Thus, an actual tool length vector V5 in which the deviation of the second rotation axis is corrected is obtained,
The actual tool length vector V5 is rotated by a command with respect to the first rotation axis based on a conversion matrix based on a reference position free from a mechanical error of the first rotation axis, an actual rotation axis deviation amount, and a command position to the first rotation axis. Accordingly, an actual tool length vector V7 in which the deviation of the first rotation axis is corrected is obtained,
Adding a command position vector and a workpiece origin offset vector to the actual tool length vector V7 to obtain a machine position;
In the numerical control method, the linear movement shaft and the rotation shaft are moved to the determined machine position.

The invention according to claim 2 is a numerical control method by a numerical controller of a machine having a linear movement shaft, a first rotation shaft for table rotation, and a second rotation shaft on the first rotation shaft,
Add the offset of the table coordinate system origin to the command position on the table coordinate system to obtain the command position on the machine coordinate system,
The command position on the machine coordinate system is only the command for the second rotation axis by a conversion matrix based on the reference position where there is no mechanical error of the second rotation axis, the actual deviation amount of the rotation axis, and the command position to the second rotation axis. Rotate, thereby obtaining the second rotational axis rotational position in which the deviation of the second rotational axis is corrected,
The second rotational axis rotational position is determined only by a command for the first rotational axis based on a conversion matrix based on a reference position where there is no mechanical error of the first rotational axis, a deviation amount of the actual rotational axis, and a command position for the first rotational axis. Rotate, thereby obtaining a first rotational axis rotational position in which the deviation of the first rotational axis is corrected,
Adding a tool length vector to the first rotational axis rotational position to obtain a machine position;
In the numerical control method, the linear movement shaft and the rotation shaft are moved to the determined machine position.

The invention according to claim 3 is a numerical control method by a numerical control device of a machine having a linear movement axis, one rotation axis for rotating the tool head, and one rotation axis for rotating the table,
Add the offset of the table coordinate system origin to the command position on the table coordinate system to obtain the command position on the machine coordinate system,
Rotate the command position on the machine coordinate system by a command for the table rotation axis by a conversion matrix based on a reference position where there is no mechanical error of the table rotation axis, a deviation amount of the actual rotation axis, and a command position to the table rotation axis, Accordingly, the table rotation axis rotation position in which the deviation of the table rotation axis is corrected is obtained,
Rotating Engineering Gucho vector by a transformation matrix shift amount of the actual rotation axis mechanical error is no reference position of the tool head rotary shaft and by the command position to the tool head rotary axis only command to the tool head rotary shaft And thereby obtaining a tool length vector in which the deviation of the rotation axis of the tool head is corrected,
Add the tool length vector to the table rotation axis rotation position to obtain the machine position,
In the numerical control method, the linear movement shaft and the rotation shaft are moved to the determined machine position.

  In the present invention, even if there is a deviation in the rotation axis or the main spindle turning axis, the machine position is instructed by correcting the deviation, so that it is possible to perform control with high machining accuracy.

There are a plurality of types (differences in configuration) of machines (machine tools) having a rotation axis. The embodiment of application of the present invention to each type of machine shall be applied to three types of machines: a tool head rotary machine, a table rotary machine, a tool head and a table rotary machine, The principle of the present invention in three embodiments will be described.
1. First embodiment of the present invention (tool head rotating type machine)
As a first embodiment of the present invention, a tool head rotary machine, which is an X, Y, Z axis linear movement axis orthogonal to each other, and an A axis (around the X axis) and C axis as rotation axes of the tool head (Around the Z axis), the C axis becomes the master axis, the A axis operates on the C axis, and the rotation angle of the A axis and the C axis is “0”, the tool direction is the Z axis direction A tool head rotating type machine will be described.

The tool length vector Vt _-H (0,0, h, 1) ^T and the workpiece origin offset amount WO _-H (WOx _-H , WOy _-H , WOz _-H , 1) ^T is assumed to be given as an initial condition. Further, hereinafter, it is expressed in a homogeneous coordinate system, and “ ^T ” means transposition.
(1-1) How to obtain the machine position when there is no deviation First, when the rotation axis center and the spindle turning center have no position deviation or inclination and no deviation or inclination from the original position, that is, there is no deviation, that is, a machining program. A case where the position and direction of the rotation axis center or the spindle turning center recognized by the control system coincide with the actual position will be described.

FIG. 1 is an explanatory diagram for explaining the calculation of the machine position when there is no deviation. Reference numeral 1 is a tool head, and reference numeral 2 is a tool.
A position command value P (x, y, z) was given to the X, Y, Z axis linear movement axes, and a position command R (a, c) was given to the A axis and C axis of the rotation axis. Then, the machine position Vm _-H (X, Y, Z, 1) ^T is obtained by the following equation (1).
Vm- _H = Mwo- _H * Mp- _H * Mc- _H * Ma- _H * Vt- _H (1)
In this equation, Mwo- _H , Mp- _H , Mc- _H and Ma- _H are transformation matrices as follows.

That is, the matrix Mwo- _H is determined by the workpiece origin offset amount WO- _H (WOx- _H , WOy- _H , WOz- _H , 1) ^T given as an initial condition, and the matrix Mp- _H , It is obtained from the position command value P (x, y, z). The matrix Mc _-H is obtained by a command c for the rotation axis C, and the matrix Ma _-H is obtained by a command a for the rotation axis A.

As shown in FIG. 1, the workpiece coordinate system origin position is obtained by adding the workpiece origin offset amount WO- _H vector set at the machine origin, and the program command value P (x , Y, z), and the tool length vector Vt _-H (0,0, h, 1) ^T when the rotation amounts of the A-axis and C-axis are “0”, The machine position Vm _-H (X, Y, Z, 1) ^T is obtained by adding the tool length vector obtained by rotating the C axis by the rotation commands a and c.

(1-2) Regarding the element of deviation (deviation of the position of the rotation center axis, main axis turning center, and inclination) The deviation that occurs in this first embodiment is (i) deviation of the C axis rotation center, (ii) A deviation of the A-axis rotation center, and (iii) a deviation of the main spindle turning center. In expressing these deviations, related items are represented by the following symbols. FIG. 2 is an explanatory diagram for explaining the calculation of the position of the machine having this deviation.
As- _H : Actual spindle turning center when A = 0, C = 0 Cs- _H : Original spindle turning center (reference position) when A = 0, C = 0
Ac _-H : Actual C axis rotation center Cc _-H : Original C axis rotation center (reference position)
Aa- _H : Actual A-axis rotation center Ca- _H : Original A-rotation center (reference position)
Further, the axis of the original C-axis rotation center (reference position) Cc- _{H and} the axis of the A-axis rotation center (reference position) Ca- _H are assumed to be orthogonal.

(I) Deviation of the actual C-axis rotation center Ac- _{H from} the original C-axis rotation center (reference position) Cc- _H (C-axis deviation).
This deviation, the actual A-axis rotation center Aa _-H from the actual deviation distance to the C-axis rotation center Ac _-H X, Y, Z-axis components _{δac -H (δacx -H, δacy -H} , δacz - _H ) and the rotational deviation (αc _-H , βc _-H , γc _-H ) around the X, Y, and Z axes around the C axis rotation center.

δac _-H (δacx _-H , δacy _-H , δacz _-H ):
The X, Y, and Z components of the separation distance from the actual A axis rotation center Aa _-H to the actual C axis rotation center Ac _-H are vectors from the actual A axis rotation center to the actual C axis rotation center. There, it is primarily in the C-axis rotation center Cc _-H and vector .delta.c _-H to the actual C-axis rotation center Ac _-H from the intersection of the original a-axis rotation center Ca _-H (δcx _-H, δcy _{- H,} When δcz _-H), a _{δac -H = -δa -H + δc -H} . (Note that δa _-H will be described later.)
(Αc _-H , βc _-H , γc _-H ):
The actual C-axis rotation center Ac _-H is inherently C axis rotation center Cc _-H, .alpha.c _-H around the X axis, .beta.c _-H around the Y axis, displacement inclined rotating [gamma] c _-H around the Z axis Represents.

(Ii) Deviation of the actual A-axis rotation center Aa- _{H from} the original A-axis rotation center (reference position) Ca- _H (A-axis deviation).
The deviation, X, Y, the linear axis of displacement .delta.a _-H of Z-axis _{(δax -H, δay -H, δaz} -H) and the rotational displacement around the axes of the A-axis rotation center (.alpha.a _-H , βa- _H , γa- _H ).
δa _-H (δax _-H , δay _-H , δaz _-H ):
X of the offset distance to the actual A-axis rotation center Aa _-H from the original A-axis rotation center Ca _-H, Y, Z components (the original C-axis rotation center Cc _-H and the original A-axis rotation center Ca _- A vector from the intersection of _H to the actual center of rotation of the A axis).
_{(Αa -H, βa -H, γa} -H):
The actual A-axis rotation center Aa _-H is original A axis rotation center Ca _-H, .alpha.a _-H around the X axis, .beta.a _-H around the Y axis, errors inclined by .gamma.a _-H rotated around the Z axis Represents.

(Iii) Deviation of the actual spindle turning center As- _{H from} the original spindle turning center (reference position) Cs- _H (shift of the spindle).
This deviation is represented by the deviation δs _-H (δsx _-H , δsy _-H , δsz _-H ) in the linear axis direction of the X, Y, and Z axes and the rotational deviation εs _-H (αs _-H , βs- _H , γs- _H ).
δs _-H (δsx _-H , δsy _-H , δsz _-H ):
X, Y, Z components of the deviation distance from the actual spindle turning center As- _H to the original spindle turning center Cs- _H (on the actual spindle turning center As- _H from the tool tip when A, C = 0) To the intersection of the original C-axis rotation center Cc- _H and the original A-axis rotation center Ca- _H ).
εs _-H (αs _-H , βs _-H , γs _-H ):
The actual spindle turning center As- _H represents an error that is tilted from the original spindle turning center Cs- _H by αs- _H around the X-axis, βs- _H around the Y-axis, and γs- _H around the Z-axis. . Including the following, the units of α, β, and γ representing the rotation angle are radians.

(1-3) How to determine the machine position when there is a deviation When there is one of the above-described three deviations of the C-axis, A-axis, and spindle (the deviation distance and the rotation amount of the linear movement axis component), It is necessary to obtain the machine position in consideration of the deviation. FIG. 2 is an explanatory diagram for obtaining the machine position in consideration of these deviations, and FIG. 3 is an explanatory diagram showing only the deviations. 4 to 6 are explanatory diagrams of the principle for obtaining the machine position in consideration of these deviations.

FIG. 4 shows a state in which the rotation axes A and C are “0”. The vector indicated by the broken line is an actual tool length vector V1 from the tool tip along the original spindle turning center Cs- _H to the intersection P1 of the original C-axis rotation center Cc- _H and the original A-axis rotation center Ca- _H. Represents. This vector becomes V2 due to the tilt error εs _-H (αs _-H , βs _-H , γs _-H ) of the main axis. Furthermore, this vector becomes V3 due to an error δs _−H (δsx _−H , δsy _−H , δsz _−H ) in the linear axis direction of the main shaft. That is, the vector V3 represents an actual tool length vector of the tool length h from the tool tip due to the deviation of the main axis when the rotation angle of the rotation axes A and C is “0”. The actual tool length vector V3 is changed to the vector V5 shown in FIG. 5 according to the deviation of the actual A-axis rotation center Aa- _{H from} the original A-rotation center Ca- _H and the rotation command a to the A-axis. That was determined by 4, the actual tool length vector V3 is the deviation of the A-axis _{δa -H (δax -H, δay -H} , δaz -H), (αa -H, βa -H, γa -H) by Instead of the vector V4, the actual center of rotation of the A axis is P2. When the tool rotates by the rotation command a to the A axis, the actual tool length vector after this rotation is V5.

Further, the actual tool length vector V5 becomes a vector V7 shown in FIG. 6 according to the deviation of the actual C-axis center Ac- _{H from} the original C-axis center Cc- _H and the rotation command c to the C-axis. Deviation of C-axis, i.e., the actual A-axis rotation center Aa _-H from the actual deviation distance to the C-axis rotation center Ac _-H X, Y, Z-axis, the components δac _-H (δacx _-H, δacy _{- H} , δacz _-H ) and the rotational deviations about the X, Y, and Z axes (αc _-H , βc _-H , γc _-H ), the center of rotation of the C axis moves to point P3 in FIG. The actual tool length vector V5 is changed to the vector V6. Then, the actual tool length vector becomes V7 by rotating around the point P3 by the C-axis rotation command value c. This point P3 is the machine position when there is a deviation. As a result, the actual tool length vector V7 obtained when the displacement command and the position command R (a, c) for the rotation axes A and C are executed is added to the position command P (x, y, z). The machine position is obtained (see FIG. 2).

Therefore, the machine position Vm _-H 'when there is a deviation can be obtained by calculating the following two expressions.
Vm _-H '= Mwo _-H * Mp _-H * Mc _-H ' * δac _-H * Ma _-H '* δa _-H * δs _-H * εs _-H * Vt _-H (2)
In the above two equations, the transformation matrices Mwo- _H and Mp- _H are as described above, and the other elements are as follows.

Explaining the above two formulas, the tool length vector Vt _-H (0,0, h, 1) ^T , which is the initial setting, the transformation matrix of the rotation error εs _-H of the X, Y, and Z axes of the spindle, and the spindle deviation seeking of X, Y, Z components .delta.s _-H over 4 to the actual tool length vector V3 shown, further, X in a-axis, Y, Z components deviation .delta.a _-H and X, Y, rotation about the Z axis deviation _{(αa -H, βa -H, γa} -H), and over the transformation matrix Ma _-H 'including a rotation command a to the a-axis determining an actual tool length vector V5 shown in Fig.

Furthermore, the transformation matrix of each component δac- _H of X, Y, Z of the deviation distance from the actual A axis rotation center Aa _-H to the actual C axis rotation center Ac _-H , and the X, Y, Z of the C axis The actual tool length vector V7 shown in FIG. 6 is obtained by multiplying the rotation deviations (αc _−H , βc _−H , γc _−H ) around the axes and the conversion matrix Mc _−H ′ including the rotation command c to the C axis.
Then, as shown in FIG. 2, a matrix Mp- _H for adding the vector of the position command value P (x, y, z) from the workpiece coordinate system origin is applied, and further a matrix Mwo- _H for adding the machine origin and workpiece origin offset vector. By applying, the machine position Vm- _H ′ at the command position where the deviation is corrected is obtained in the machine having the deviation.

2. Second embodiment of the present invention (table rotary machine)
As a second embodiment of the present invention, an example of a machine in which a table for mounting a workpiece on two rotating shafts rotates will be described. As shown in FIG. 7, the X axis, the Y axis, and the Z axis linear movement axes are orthogonal, and the A axis (around the X axis) and the C axis (around the Z axis) are provided as the rotation axes of the table 3, and the A axis is the master axis. Thus, it is assumed that the C-axis operates on the A-axis, and the A-axis rotation center Ca- _T and the C-axis rotation center Cc- _T are orthogonal to each other. The tool direction is the Z-axis direction.

In this case of the second embodiment, the tool length vector _{Vt --T (0,0, h, 1} ) T, workpiece origin offset _{WO -T (WOx -T, WOy -T} , WOz -T, 1) ^T , the intersection vector Co- _T (Cox- _T , Coy- _T , Coz- _T , 1) ^T of the rotation center Ca _- ^{T of} the A-axis and the rotation center Cc _{- T} of the C-axis is given as an initial condition And

(2-1) Determination of machine position when there is no deviation Position command value P (x, y, z) for the X, Y, Z coordinates on the table coordinate system (work coordinate system), and rotation axes A, C When the position command R (a, c) for is given, the machine position Vm _-T (XYZ, 1) ^T is obtained by the following three equations.
Vm _-T = Mvt _-T * Mad _-T * Mcd _-T * Mwo _-T * P _-T (3)
Each conversion matrix of the elements in these three formulas is as follows.

That is, as shown in FIG. 7, a vector P _-T of a position P (x, y, z) commanded on the table coordinate system (work coordinate system) is changed from the machine coordinate origin to the table coordinate system (work coordinate system). By applying a matrix Mwo- _T for adding the workpiece origin offset vector to the origin, the command position when the rotation axes A and C do not rotate can be obtained. On the other hand, by applying a conversion matrix Mcd- _T for rotating the C axis by the command position c, the command position when the C axis is rotated by the command c is obtained. Further, by applying a conversion matrix Mad- _T that rotates the A axis by the command position a, the command position when the A axis is rotated by the command a can be obtained. The machine position Vm- _T is obtained by multiplying this by a matrix Mvt- _T to which the tool length vector is added.

The three formulas for determining the machine position are compared with one formula in the head rotation formula, and the conversion matrixes Mc _-H and Ma _-H in the formula 1 and the transformation matrices Mc _-T and Mai _-T in the formula 3 are inverted in sign of angle. is doing. This is because the head rotates in the commanded direction with respect to the command angle (clockwise when the vector tip side is viewed from the base side of the rotation axis vector vector, but the table rotates in the opposite direction). Because.

(2-2) Elements of deviation (deviation of position of rotation center axis, main axis turning center, and inclination) In the second embodiment (table rotation type), (i) deviation of C axis rotation center, ( ii) It is assumed that there is a shift of the A-axis rotation center. Therefore,
Ac- _T : Actual C-axis rotation center Cc- _T : Original C-axis rotation center (reference position)
Aa- _T : Actual A-axis rotation center Ca- _T : Original A-axis rotation center (reference position)
Then,

(I) C axis rotation center shift,
Actual C-axis rotation center Ac original C-axis rotation center (reference position) Cc linear movement axis deviation relative to _-T X of _-T, Y, and Z-direction displacement _{δc -T (δcx -T, δcy -T} , δcz _−T ) and rotational deviations about each axis (αc _−T , βc _−T , γc _−T ).
δc _-T (δcx _-T , δcy _-T , δcz _-T ):
X, Y, and Z components of the separation distance from the actual C-axis rotation center Ac- _T to the original C-axis rotation center Cc- _T . This is expressed as a vector from the intersection of the original C-axis rotation center Cc- _T and the original A-axis rotation center Ca- _T to the actual C-axis rotation center.
(Αc _-T , βc _-T , γc _-T ):
The actual C-axis rotation center Ac _-T is the original C-axis rotation center Cc _-T, .alpha.c _-T around the X axis, .beta.c _-T around the Y axis, to be inclined by rotating [gamma] c _-T around the Z axis Expressed as misalignment.

(Ii) Deviation of the A-axis rotation center The deviation of the actual A-axis rotation center Aa- _{T from} the original A-axis rotation center (reference position) Ca- _T is expressed as follows.
δa _-T (δax _-T , δay _-T , δaz _-T ):
This is represented by X, Y, and Z components of the deviation distance from the original A-axis rotation center Ca- _T to the actual A-axis rotation center Aa- _T . This is expressed as a vector from the intersection of the original C-axis rotation center Cc- _T and the original A-axis rotation center Ca- _T to the actual A-axis rotation center.
_{(Αa -T, βa -T, γa} -T):
The actual A-axis rotation center Aa _-T is the original A-axis rotation center Ca _-T, .alpha.a _-T around the X axis, .beta.a _-T around the Y axis, deviation are inclined rotating .gamma.a _-T around the Z axis Represent as
In the second embodiment, it is assumed that there is no deviation from the tool length vector Vt- _T .

(2-3) How to obtain machine position when there is a deviation The machine position of the machine with a deviation in the second embodiment is the following calculation formula corresponding to the above-described three formulas for obtaining the machine position when there is no deviation. The following four formulas.
Vm _-T '= Mvt _-T * Mad _-T ' * Mcd _-T '* Mwo _-T * P _-T (4)
The conversion matrix of the elements shown in Formula 4 is as follows.

The vector P _{-T of} the command position P (x, y, z) and the workpiece origin offset amount WO _-T (WOx _-T , WOy _-T , WOz _-T , 1) ^T conversion matrix Mwo _-T , tool The matrix Mvt _- ^T of the long vector Vt- _T (0,0, h, 1) ^T is as described above.

As shown in FIG. 8, the vector P _-T of the command position P (x, y, z) on the table coordinate system is added to the vector of the workpiece origin offset amount WO _-T to obtain the command position on the machine coordinate system. Ask. Then, a conversion matrix Mcd- _T ′ according to the C axis deviation δc _{- T} (δcx- _T , δcy- _T , δcz- _T ), (αc- _T , βc _{- T} , γc _{- T} ) and the command c to the C axis. To correct the deviation of the C axis and obtain the position where the C axis is rotated by the command c. Furthermore, the deviation of the A-axis _{δa -T (δax -T, δay -T} , δaz -T), (αa -T, βa -T, γa -T) transformation matrix by the command a to the A-axis and Mad _-T ' To correct the deviation of the A axis and obtain the position where the A axis is rotated by the command a. Then, the machine position Vm _-T 'is obtained by multiplying the matrix Mvt _-T of the tool length vector Vt _-T (0,0, h, 1) ^T.

3. Third embodiment of the present invention (machine in which a tool head and a table rotate)
As a third embodiment of the present invention, the table 3 is rotated by one rotation axis (C axis) and the tool head 1 is rotated by another rotation axis (B axis). The rotation about the Z axis and the B axis is about the Y axis. Further, the tool direction when the rotation axis positions are both 0 (B, C = 0) is the Z direction.
In the third embodiment, the following data is given as an initial condition.
・ Tool length vector Vt _-M (0,0, h, 1) ^T
・ Workpiece origin offset amount WO _-M (WOx _-M , WOy _-M , WOz _-M , 1) ^T
・ C-axis rotation center Cc _-M (Ccx _-M , Ccy _-M , Ccz _-M , 1) ^T

(3-1) Method for obtaining machine position when there is no deviation In the third embodiment, the position command value P (x, y, z) on the table coordinate system for X, Y, Z and the rotation axis When the position command value R (b, c) for the B and C axes is given, the following calculation is performed to obtain the machine position Vm _-M (x, y, z, 1) ^T corrected for the tool length.
Vp _-M = Mcd _-M * Mwo _-M * P _-M (5)
Vv _-M = Mb _-M * Vt _-M (6)
Then,
Vm _-M = Vp _-M + Vv _-M (7)
Each element in the above formulas 5 to 7 is as follows.

That is, as shown in FIG. 9, the position command value P on the table coordinate system (x, y, z) workpiece zero offset vector P _-M showing the amount _{WO -M (WOx -M, WOy -M} , WOz - _M , 1) The vector Mwo- _M of ^T is added, and further, the command position Vp- _M after rotating the C-axis by the command c is obtained by applying the rotation conversion matrix Mcd- _M of the C-axis rotation command c. (Formula 5).
Further, the tool length vector Vt- _M is obtained by multiplying the tool length vector Vt- _M by the rotation conversion matrix Mb- _M for rotating the B axis by the command b to obtain the tool length vector Vv- _M by rotating the B axis by b (Equation 6).
Then, as shown in the above equation 7, the machine position Vm is obtained by adding the tool length vector Vv _-M obtained by rotating the B axis by b to the command position Vp _-M after rotating the C axis by the command c. _-M is found.

(3-2) Elements of deviation (deviation of rotation center axis, deviation of position of spindle turning center, and inclination) The deviation that occurs in this third embodiment (tool head and table rotation type) is (i) C axis Rotation center deviation, (ii) B axis rotation center deviation. Therefore,
Ac _-M : Actual C axis rotation center Cc _-M : Original C axis rotation center (reference position)
Ab- _M : Actual B-axis rotation center Cb- _M : Original B-axis rotation center (reference position)
Then,

(I) C axis rotation center shift,
The deviation of the actual C-axis rotation center Ac- _{M from} the original C-axis rotation center (reference position) Cc _{- M is} defined as the deviation δc _{- M} (δcx- _M , δcy- _M , δcz in the linear movement axis X, Y, Z direction. _-M ) and rotational deviations about each axis (αc _-M , βc _-M , γc _-M ).
δc _-M (δcx _-M , δcy _-M , δcz _-M ):
X, Y, and Z components of the separation distance from the actual C-axis rotation center Ac- _M to the original C-axis rotation center Cc- _M .
(Αc _-M , βc _-M , γc _-M ):
The actual C-axis rotation center Ac _-M is inherently C axis rotation center Cc _-M, .alpha.c _-M around the X axis, .beta.c _-M around the Y axis, to be inclined by rotating [gamma] c _-M around the Z axis This represents a gap.

(Ii) Deviation of the B-axis rotation center The deviation of the actual B-axis rotation center Ab- _{M from} the original B-axis rotation center (reference position) Cb- _M is expressed as follows.
δb _-M (δbx _-M , δby _-M , δbz _-M ):
This is represented by X, Y, and Z components of the separation distance from the original B-axis rotation center Cb _{- M} to the actual B-axis rotation center Ab _{- M} .
_{(Αb -M, βb -M, γb} -M):
The actual B-axis rotation center Ab _-M is original B-axis rotation center Cb _-M, .alpha.b _-M around the X axis, .beta.b _-M around the Y axis, to be inclined by rotating .gamma.b _-M around the Z axis Represents that
It is assumed that there is no deviation from the tool length vector Vt- _M .

(3-3) How to determine the machine position when there is a deviation The machine position of the machine with a deviation in the third embodiment is a calculation formula corresponding to the above-described formulas 5 to 7 for obtaining the machine position when there is no deviation. Is the following 8-10 formula.
Vp _-M '= Mcd _-M ' * Mwo _-M * P _-M (8)
Vv _-M '= Mb _-M ' * δb _-M * Vt _-M (9)
Vm- _M '= Vp- _M ' + Vv- _M '(10)
Each element in the above 8 to 10 expressions is as follows.

That is, as shown in FIG. 10, the position command value P on the table coordinate system (x, y, z) workpiece zero offset vector P _-M showing the amount _{WO -M (WOx -M, WOy -M} , WOz - _M , 1) The command position on the machine coordinate system is obtained by multiplying the matrix Mwo- _M to which the vector of ^T is added. Then, the conversion matrix Mcd- _M ′ according to the C-axis command δc _{- M} (δcx- _M , δcy- _M , δcz- _M ), (αc- _M , βc _{- M} , γc _{- M} ) and the C-axis command c. To correct the deviation of the C axis and obtain the position Vp- _M ′ obtained by rotating the C axis by the command c (Equation 8).

Also, the tool length vector Vt _-M is multiplied by a matrix δb _-M that adds the vector of deviations of the X, Y, and Z components of the B axis, and further, the B axis rotation deviation is corrected and the B axis is rotated by the command b. By applying the conversion matrix Mb- _M ′ to be corrected, the rotational deviation of the B-axis is corrected, and a tool length vector Vv- _M ′ obtained by rotating the B-axis by the command b is obtained (Equation 9).
Then, as shown in the above equation 10, by adding the tool length vector Vv _-M 'obtained by rotating the B axis by b to the command position Vp _-M ' after rotating the C axis by the command c, the machine A position Vm- _M ′ is obtained.

(4) For other machines,
The case where the center of rotation of the spindle is displaced from the reference position has been described only for the tool head rotating machine, but it is also applicable to the table rotating machine and the machine where the tool head and table rotate. Is something that can be done.

Further, in the case of a tool head rotating type machine, the case where the main spindle turning center is deviated from the reference position has been described. , if the spindle turning center Cs _-H does not intersect the a-axis rotation center Ca _-H or, as shown in FIG. 12, the machine table is rotated, C axis rotational center Cc _-T and a-axis rotation center Ca _{- The} present invention can also be applied when _T does not intersect.

Furthermore, in the case of a tool head rotary machine and in the case of a table rotary machine, the rotation axes are orthogonal to each other, but the present invention can also be applied to a case where they are not orthogonal.
In addition, regarding the configuration of the rotary shaft, in each of the above-described embodiments, the C and A axes in the case of a tool head rotary machine, the A and C axes in the case of a table rotary machine, and the tool head and table rotate. In the case of a machine, the C and B axes are used. However, the present invention can also be applied to machines having other shaft configurations, and naturally, the present invention can also be applied to a machine having only one rotating shaft.
Furthermore, when the rotation axis position = 0, the tool direction is the Z-axis direction, but the present invention can naturally be applied to other axial directions.

FIG. 13 is a block diagram of a numerical control apparatus that implements the method of each embodiment for obtaining the machine position by correcting the deviation described above.
The CPU 11 is a processor that controls the numerical controller 100 as a whole. The CPU 11 reads a system program stored in the ROM 12 via the bus 20 and controls the entire numerical control device according to the system program. The RAM 13 stores temporary calculation data, display data, and various data input by the operator via the display / MDI unit 70. The CMOS memory 14 is configured as a non-volatile memory that is backed up by a battery (not shown) and that retains the memory state even when the numerical controller 100 is turned off. In the CMOS memory 14, a machining program read via the interface 15, a machining program input via the display / MDI unit 70, and the like are stored. The ROM 12 also stores software for performing the arithmetic processing of the above-described formulas 1 to 10 for performing the deviation correction of the present invention.

  The interface 15 enables connection between the numerical controller 100 and an external device 72 such as an adapter. A machining program or the like is read from the external device 71 side. Further, the machining program edited in the numerical control apparatus 100 can be stored in the external storage means via the external device 72. A PMC (programmable machine controller) 16 outputs a signal to an auxiliary device of a machine tool (for example, an actuator such as a robot hand for tool change) via an I / O unit 17 and controls it with a built-in sequence program. Note that the PMC may be provided on the machine side. It receives signals from various switches on the operation panel provided in the machine tool body, performs necessary signal processing, and passes them to the CPU 11.

  The display / MDI unit 70 is a manual data input device having a display, a keyboard, and the like. The interface 18 receives commands and data from the keyboard of the CRT / MDI unit 70 and passes them to the CPU 11.

  The axis control circuits 30 to 33 for each axis receive the movement command amount for each axis from the CPU 11 and output the command for each axis to the servo amplifiers 40 to 43. In response to this command, the servo amplifiers 40 to 43 drive the servo motors 50 to 53 of the respective axes (X, Y, Z axes and rotation axes of the linear movement axes). The servo motors 50 to 53 for each axis have a built-in position / speed detector, and a position / speed feedback signal from the position / speed detector is fed back to the axis control circuits 30 to 33 to perform position / speed feedback control. . In FIG. 13, the position / velocity feedback is omitted.

  Further, the spindle control circuit 60 receives the spindle turning command and outputs a spindle speed signal to the spindle amplifier 61. The spindle amplifier 61 receives the spindle speed signal and rotates the spindle motor 62 at the commanded rotational speed. The position coder 63 feeds back a feedback pulse to the spindle control circuit 60 in synchronization with the rotation of the spindle motor 62 to perform speed control.

  The configuration of the numerical control device described above is not different from the configuration of the conventional numerical control device. However, as described above, the software that corrects the machine deviation and outputs the command position is stored in the storage means, and the deviation of the rotation axis center from the original position and the inclination deviation, the original rotation center of the spindle A function that is not included in the conventional numerical control device that corrects a deviation from the position and a deviation represented by an inclination and outputs a movement command to the machine is added.

First, when the numerical control device 100 is attached to a machine, the above-described deviation is set and registered in the numerical control device according to the type of the machine. That is, in the case of the first embodiment in which the machine is a tool head rotation type machine and has the A and C axes as the rotation axes, the deviation of the C axis, δac _-H (δacx _-H , δacy _{-H , δacz -H), (αc -H} , βc -H, γc -H), displacement of the a-axis _{δa -H (δax -H, δay -H} , δaz -H), (αa -H, βa -H, γa _-H ), main axis deviation δs _-H (δsx _-H , δsy _-H , δsz _-H ), εs _-H (αs _-H , βs _-H , γs _-H ) are set.

Further, in the case of the machine table it has been described as a second embodiment the rotating deviation .delta.c _-T in the C-axis _{(δcx -T, δcy -T, δcz} -T), (αc -T, βc -T, [gamma] c _-T), the deviation of the a-axis _{δa -T (δax -T, δay -T} , δaz -T), sets the _{(αa -T, βa -T, γa} -T). In the case of the machine described as the third embodiment, the deviation .delta.c _-M in the C-axis _{(δcx -M, δcy -M, δcz} -M), (αc -M, βc -M, γc -M ), B axis deviations δb _-M (δbx _-M , δby _-M , δbz _-M ), (αb _-M , βb _-M , γb _-M ) are set.

  As a method for setting these deviation amounts, parameters are set in the CMOS memory 14 or the like in the numerical controller 100. Alternatively, these error amounts are stored in advance in the machine, and when the machine is connected to the numerical controller 100, the deviation amount is transmitted from a PLC (programmable logic controller) provided on the machine side, and this is sent in. Set the amount of deviation. Furthermore, the amount of deviation is received by communication from an external computer via the interface 15 or the like and set.

  In the numerical control device 100, the type of machine connected, that is, the type of machine such as a tool head rotating type machine, a table rotating type machine, or a machine in which the tool head and the table rotate is set. deep. Note that the tool length, workpiece origin (work origin offset), and in the case of a table rotation type machine, the intersection of the A-axis rotation center and the C-axis rotation center is set, and the tool head and table rotate. In this case, it is assumed that the C-axis rotation center position is set.

  FIG. 14 is a flowchart of a tool length correction process executed by the numerical controller 100. First, the CPU 11 determines whether or not a deviation amount is set (step 1). If the deviation amount is not set, the CPU 11 determines the set machine type (type) (step 2), and the tool head. If the machine is a rotary machine, the above-described one set of calculation processing is selected (step 3), and thereafter, one set of calculations is performed on the position command commanded by the program to perform tool length correction processing.

  If the machine is a table rotating type machine, select 3 types of arithmetic processing (step 4). If the tool head and table rotate, select 5-7 type arithmetic processing (step 5). The tool length compensation process is performed by performing the selected computation process for the position command commanded by the program.

  If the deviation is set, the machine configuration (type) is discriminated (step 6). If the tool head is a rotary machine, the above-described two types of arithmetic processing are selected (step 7). In the case of a table rotating type machine, four types of arithmetic processing are selected (step 8), and in the case of a machine in which the tool head and the table are rotated, the arithmetic processing of eight to ten types is selected (step 9). The tool length correction process is performed by performing the selected calculation process for the position command commanded in step (b).

  The calculation of the tool length correction can be performed for each block, but can also be performed at an interpolation cycle or at other timing in the numerical controller.

It is explanatory drawing explaining the calculation of the machine position in the case where there is no deviation in the machine which has the rotation axis of A axis and C axis. It is explanatory drawing of machine position calculation when there exists deviation in the same machine. It is an enlarged explanatory view of a shift part in the machine. It is explanatory drawing of the change of the tool length vector by the shift | offset | difference of a spindle turning center in the same machine. In the same machine, it is explanatory drawing of the change of the tool length vector by the shift | offset | difference of the A-axis rotation center, and the instruction | command to A-axis. It is explanatory drawing of the change of the tool length vector by the shift | offset | difference of a C-axis rotation center, and the instruction | command to C-axis in the same machine. It is explanatory drawing of how to obtain | require a machine position when there is no shift | offset | difference in the machine which has the rotating shaft A and C axis | shaft in a table. It is explanatory drawing of how to obtain | require a machine position when there exists deviation | shift in the machine which has the rotating shaft A and C axis | shaft in a table. It is explanatory drawing of how to obtain | require a machine position when there is no shift | offset | difference in the machine which has a rotating shaft in a tool head and a table. It is explanatory drawing of how to obtain | require a machine position when there exists a shift | offset | difference in the machine which has a rotating shaft in a tool head and a table. It is explanatory drawing of the machine in which the spindle turning center which can apply this invention does not cross | intersect the A-axis rotation center. In the machine in which the table to which the present invention can be applied is rotated, the C axis rotation center and the A axis rotation center do not intersect with each other. It is a principal part block diagram of one Embodiment of the numerical control apparatus which correct | amends the shift | offset | difference of each machine, and performs tool length correction | amendment. It is a process flowchart of the tool length correction | amendment which one Embodiment of the same numerical control apparatus performs.

Explanation of symbols

1 Tool head 2 Tool 3 Table

Claims (3)

A numerical control method by a numerical controller of a machine having a linear movement axis, a first rotation axis for rotating a tool head, and a second rotation axis on the first rotation axis,
An actual tool length vector V3 in which the tool length vector is corrected by a conversion matrix based on a deviation position between the spindle center of rotation without a mechanical error and the actual spindle center of rotation is obtained.
The actual tool length vector V3 is rotated by a command for the second rotation axis by a conversion matrix based on a reference position free from a mechanical error of the second rotation axis, an actual rotation axis shift amount, and a command position to the second rotation axis. Thus, an actual tool length vector V5 in which the deviation of the second rotation axis is corrected is obtained,
The actual tool length vector V5 is rotated by a command with respect to the first rotation axis based on a conversion matrix based on a reference position free from a mechanical error of the first rotation axis, an actual rotation axis deviation amount, and a command position to the first rotation axis. Accordingly, an actual tool length vector V7 in which the deviation of the first rotation axis is corrected is obtained,
Adding a command position vector and a workpiece origin offset vector to the actual tool length vector V7 to obtain a machine position;
A numerical control method, wherein the linear movement axis and the rotation axis are moved to the determined machine position. A numerical control method by a numerical controller of a machine having a linear movement axis, a first rotation axis for table rotation, and a second rotation axis on the first rotation axis,
Add the offset of the table coordinate system origin to the command position on the table coordinate system to obtain the command position on the machine coordinate system,
The command position on the machine coordinate system is only the command for the second rotation axis by a conversion matrix based on the reference position where there is no mechanical error of the second rotation axis, the actual deviation amount of the rotation axis, and the command position to the second rotation axis. Rotate, thereby obtaining the second rotational axis rotational position in which the deviation of the second rotational axis is corrected,
The second rotational axis rotational position is determined only by a command for the first rotational axis based on a conversion matrix based on a reference position where there is no mechanical error of the first rotational axis, a deviation amount of the actual rotational axis, and a command position for the first rotational axis. Rotate, thereby obtaining a first rotational axis rotational position in which the deviation of the first rotational axis is corrected,
Adding a tool length vector to the first rotational axis rotational position to obtain a machine position;
A numerical control method, wherein the linear movement axis and the rotation axis are moved to the determined machine position. A numerical control method using a numerical control device of a machine having a linear movement axis, a rotary axis for rotating a tool head, and a rotary axis for rotating a table,
Add the offset of the table coordinate system origin to the command position on the table coordinate system to obtain the command position on the machine coordinate system,
Rotate the command position on the machine coordinate system by a command for the table rotation axis by a conversion matrix based on a reference position where there is no mechanical error of the table rotation axis, a deviation amount of the actual rotation axis, and a command position to the table rotation axis, Accordingly, the table rotation axis rotation position in which the deviation of the table rotation axis is corrected is obtained,
Rotating Engineering Gucho vector by a transformation matrix shift amount of the actual rotation axis mechanical error is no reference position of the tool head rotary shaft and by the command position to the tool head rotary axis only command to the tool head rotary shaft And thereby obtaining a tool length vector in which the deviation of the rotation axis of the tool head is corrected,
Add the tool length vector to the table rotation axis rotation position to obtain the machine position,
A numerical control method, wherein the linear movement axis and the rotation axis are moved to the determined machine position.

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