JP5399881B2 - Numerical control device for 5-axis machine - Google Patents

Description

  The present invention relates to a numerical control device for controlling a 5-axis machining machine that processes a workpiece (workpiece) fixed and attached to a table by three linear axes and two rotary axes.

  The 5-axis processing machine includes a head rotating type (see FIG. 1) in which the head rotates, a table rotating type (not shown) in which the table rotates, and a mixed type (not shown) in which the head and the table rotate.

  In FIG. 1, the machine control point is a point where the rotation centers of the two rotation axes intersect. In FIG. 2 and subsequent figures, only the portion (TS) and the tool for supporting the tool of the tool head are drawn for the sake of simplicity. In addition, in order to make the A-axis and C-axis positions easy to understand, the shape of the part (TS) that supports the tool and the tool is slightly changed and drawn longer.

  Patent Document 1 discloses a method for controlling the coordinate value of each axis in a numerical control device for controlling a 5-axis processing machine that processes a workpiece (workpiece) attached to a table with three linear axes and two rotary axes. Command the tool position, tool posture (relative posture of the tool with respect to the workpiece) and speed on the Cartesian coordinate system (table coordinate system) fixed to the table, and this is the coordinates of each axis at the machine control point A technique of tool tip point control, which is a method of controlling by converting coordinates into values, is disclosed.

  In the tool tip point control, the position and speed of the tool are controlled, and the tool posture is determined by interpolating the position of each rotation axis. In the tool tip point control, the position and speed of the tool tip point are controlled, but the two rotation axes are controlled independently, and the tool posture in the middle of the command block is not controlled.

  On the other hand, Patent Literature 2 and Patent Literature 3 include the tool posture calculated based on the command rotation axis positions at the command block start point and the command block end point, between the command block start point and the command block end point. A technique of tool posture control, which is a method of controlling the rotation axis position and the linear axis position for each sampling period so as to exist in a plane or a smooth surface, is disclosed. In the tool attitude control, a tool attitude command may be based on a rotation axis position command or a vector command.

  In the tool posture control, the tool posture in the middle of the command block moves in a plane or a smooth surface including the tool posture at the command block start point and end point. Is used for machining on the side of the tool. In addition, since the tool posture control can easily predict a change in the tool posture, unexpected interference and collision between the machine structure and the tool can be prevented.

  On the other hand, in the tool posture control, the operation of the rotary shaft may become unstable in order to keep the tool posture in a plane including the tool posture at the start point and the end point of the command block or in a smooth plane. For example, when tool posture control is performed in a machine having a singular point (singular point posture) where the position of one of the two rotation axes is arbitrary (undefined), the tool posture in the middle of the command block is a singular point. When a command to pass near is given, the speed and acceleration of the rotation axis may become very large near a singular point.

  In Patent Document 4, a range in the vicinity of a singular point is determined so that the posture error of the tool is not more than the allowable posture error value, and the tool tip point control is performed in the range, and the tool posture control is performed in the other range. Thus, a technique is disclosed in which the tool posture error satisfies the required accuracy, the speed and acceleration of the rotating shaft at a singular point is suppressed, and the moving time of the tool is shortened as much as possible.

Japanese Patent Laid-Open No. 2003-195917 JP 2005-182437 A JP 2007-293522 A JP 2004-220435 A

Here, a description will be given of a case where a tool posture command is based on a rotation axis position command and a vector command in the tool posture control. Note that a rotation axis in which the speed and acceleration are very large near a singular point is called a turning rotation axis, and the other rotation axis is called a tilt rotation axis. In the machine configuration of FIG. 1, the A axis is an inclined rotation axis, and the C axis is a turning rotation axis. When a tool posture in the Z-axis direction is commanded, A = 0 degrees, but the position of the C-axis is arbitrary (undefined). That is, the tool posture is in the Z-axis direction regardless of whether C = 0 ° or C = 180 °. Therefore, a singular point is a position where the tool posture is in the Z-axis direction or the A-axis position is 0 degrees.
However, there is a machine configuration in which the state of FIG. 23 is A = 0 degrees and the state of FIG. 1 is A = 90 degrees. In the case of the machine configuration, the position where the A axis is 90 degrees is a singular point. Furthermore, the singular point is not A = 0 degrees or 90 degrees, and may be at other angles. In the following description, it is assumed that the state of FIG. 1 is A = 0 degree and the position where the A-axis position is 0 degree is a singular point, but the position where the tilt rotation axis position is 0 degree is not necessarily a singular point.
First, the case of the rotation axis position command will be described.

  When the tool posture control is performed by the tool posture command commanded at the position of the rotation axis (A, C axis), the command end point (A20, C-30) is commanded from the state of the command start point (A-20, C30). Then, the relationship between the command start point and the command end point is commanded as shown in FIG.

An example of the command program is <command example 1> below.
<Command example 1>
N10 G43.4P1X1.2Y3.0Z5.0A-20.0C30.0H01;
N20 Y0.0A20.0C-30.0;
...
N90 G49;
Here, “N10”, “N20”, and “N90” represent block numbers. “G43.4” is a G code for performing tool tip point control by a rotation axis position command, and further performing tool posture control by commanding P1. X, Y, and Z are commands for the position at which the tool tip point moves, and A and C commands the direction of the tool posture based on the A and C axis positions. H01 commands a tool length correction amount number for performing tool tip point control or tool posture control. G49 is a command for canceling the tool tip point control or the tool attitude control.

  At N10, the tool tip is operated according to the Y command, and since the relationship between the command start point and the command end point as shown in FIG. 2 is commanded when focusing only on the tool posture, the tool posture is on the hatched plane in FIG. This command is expected to operate on the smooth surface of No. 4.

  In the specification attached to the present application (hereinafter referred to as “the present specification”), for the sake of simplicity, the tool posture is controlled not to be on a smooth surface as shown in FIG. 4 but to be present on a plane as shown in FIG. Will be described below. In addition, FIGS. 2 to 4 and the subsequent drawings depicting the operation of the tool head or the tool are views focusing only on the operation of the tool head or the tool. In the actual command, X, Y, and Z are normally commanded together with the commands A and C as described above, and the tool tip operates corresponding to the commanded X, Y, and Z. However, in the drawings attached to the present application, the movement of the tool tip in the X, Y, and Z directions is omitted (there is no movement on the drawing) and only the movement of the tool head or the tool is considered.

  Here, when interpolation is performed to change the tool posture from the command start point tool posture to the command end point tool posture every sampling cycle on the plane of FIG. 3, the tool tip is normalized to the machine control point in each sampling cycle. For the tool posture vector Vt (Vtx, Vty, Vtz) (see FIG. 1), the solutions for the A-axis and C-axis are usually two sets (Formula 1 and Formula 2). B) exists.

Here, it is assumed that the arccos calculation obtains a value of 0 to 180 degrees. Moreover, it is assumed that the value of arctan is obtained as follows.
When Vtx, Vty ≧ 0, 0 degree to 90 degree Vtx <0, When Vty ≧ 0, When 90 degree to 180 degree Vtx <0, When Vty <0, 180 degree to 270 degree Vtx ≧ 0, Vty <0 In the case of 270 degrees to 360 degrees
In the calculation of arctan, n in the term of n * 360 degrees is an integer value, and a position obtained by adding a value of n times 360 degrees is a solution. That is, the C-axis can operate in any number of rotations in the positive and negative directions, but the A-axis can operate within −180 degrees to 180 degrees.

  If a solution close to the immediately preceding A-axis and C-axis positions is selected from the two sets of solutions, the operation is as shown in FIG. An example of such an operation is disclosed in Japanese Patent Application Laid-Open No. 9-207089 (Claim 2).

The operation shown in FIG. 5 will be described. A description will be given in order from FIG. As described above, the intermediate point 1 includes the intermediate point 1A (A-13.409, C49.764) and the intermediate point 1B (A13.409, C-130.236). The position of the intermediate point 1B is a position opposite to the intermediate point 1A, and is another solution of the two sets of solutions. The tool moves to an intermediate point 1A (A-13.409, C49.764) close to the start point (A-20, C30) which is the immediately preceding position.
As shown in FIG. 5B, the intermediate point 2 has two solutions, the intermediate point 2A and the intermediate point 2B, but the intermediate point 2A close to the immediately preceding position (intermediate point 1A) is selected. As shown in FIG. 5C, the intermediate point 3 has two solutions of the intermediate point 3A and the intermediate point 3B, but the intermediate point 3A close to the immediately preceding position (intermediate point 2A) is selected. The end point has two solutions, the end point A and the end point B, and the end point A close to the immediately preceding position (intermediate point 3A) is selected. This position is not the “command end position”, but the command end position is the end point B. As shown in FIG. 5D, the commanded end point position is not reached. Therefore, it is against the command. That is, it is physically impossible to operate on the hatched plane of FIG. 3 by the command of FIG.

Since it is physically impossible, it is inevitable that the tool cannot move toward the commanded end point on the plane where the tool posture is expected. For this reason, when such a command block is commanded, the conventional numerical control device controls as follows.
(1) Stop the machine tool with an alarm.
(2) In a block with such a command, tool posture control is not performed but tool tip point control is performed.
(3) As shown in FIG. 5, a solution close to the immediately preceding position is selected. For example, the technique disclosed in JP 09-207089 A (Claim 2) is used.

However, the methods (1) to (3) have the following problems.
The method (1) is not desirable because the machining is not performed by stopping the machine.
In the method (2), if the tool posture control is not performed, a smooth machining surface cannot be obtained when a smooth workpiece side surface is machined on the tool side surface. A step is generated on the processing surface between the front and rear blocks. Since the tool posture is not controlled, a cut is generated on the machined surface.
In the method (3), the end point position is different from the command position, and there is a possibility that the tool collides (interferences) with a machine part or the like. In addition, the speed of the rotating shaft increases near the singular point, and if it tries to exceed the maximum speed of the rotating shaft, it takes a long time because it is limited by the maximum speed.

Next, the case of a vector command will be described.
The tool posture can be commanded by a tool posture vector indicating the tool posture direction, instead of commanding the rotation axis position by the A and C axes. The command program is as shown in <Command example 2>.
<Command example 2>
N10 G43.5P1X1.2Y3.0Z5.0I-0.171J0.296
K0.94H01;
N20 Y0.0I-0.171J-0.296K0.94;
...
N90 G49;
Here, G43.5 is a G code for performing tool tip point control by commanding a tool posture vector, and further performing tool posture control by commanding P1. X, Y, and Z are commands for the position at which the tool tip moves, and I, J, and K are commands for the tool attitude vector. H01 commands a tool length correction amount number for performing tool tip point control or tool posture control. G49 is a command for canceling the tool tip point control or the tool attitude control.
The same problem may occur when the tool posture is commanded by a tool posture vector instead of the rotation axis position command that commands the A-axis and C-axis positions. When the same command as in FIG. 3 is commanded with the tool posture vector, the path of the tip of the tool posture vector is interpolated and changed as shown by the broken line in FIG. The tool posture vector is normalized (length = 1). For the sake of simplicity, the vector is drawn longer than the tool posture vector of FIG.

It is assumed that the tool posture is commanded by the start tool posture vector Vs (Vsx, Vsy, Vsz) at the command start point, and the tool posture is commanded by the end point tool posture vector Ve (Vex, Vey, Vez) at the command end point. FIG. 7 shows the angle θcs between the intermediate point tool posture vector Vc (Vcx, Vcy, Vcz) and the singular point tool posture vector Vsi (0, 0, 1), and the intermediate point tool posture vector Vc (Vcx, Vcy, Vcz). It is a figure explaining the distance Lcs of the vector front-end | tip position with singular point tool posture vector Vsi (0, 0, 1).
Here, it is assumed that the tool posture is sufficiently close to the singular point. That is, it is assumed that the following condition (4) or (5) is satisfied in the intermediate point tool posture vector Vc (Vcx, Vcy, Vcz). Note that the intermediate point does not mean that it is exactly between the command start point and the command end point. It is the point closest to the singular point between the command start point and the command end point. The “closest point” is an angle with the singular point tool posture vector indicating the tool posture at the singular point or a position where the distance of the vector tip position from the singular point is the shortest.

(4) The angle θcs between the intermediate point tool posture vector Vc (Vcx, Vcy, Vcz) and the singular point tool posture vector Vsi (0, 0, 1) is smaller than a certain set value θs.

  Here, θcs is θcs = arccos (Vc · Vsi) (the symbol “·” is an inner product).

(5) The distance Lcs of the vector tip position between the intermediate point tool posture vector and the singular point tool posture vector is smaller than a set value Ls.

Here, Lcs is Lcs = sin θcs
However, Lcs = TL * sin θcs may be set in consideration of other lengths (TL) such as a tool length.

  In the conventional numerical control device, a solution close to the immediately preceding rotational axis position is selected. Therefore, in the case of (4) or (5) above, the operation is the same as in FIG. In this case, since it is commanded by the tool posture vector, the “end point position becomes a position different from the command position” will not occur. However, the speed of the rotating shaft increases in the vicinity of the singular point, and if it tries to exceed the maximum speed of the rotating shaft, it is limited to the maximum speed, and therefore processing time is required.

  Therefore, in Patent Document 4, tool posture control is not performed at an intermediate point of a block having such a command or in the vicinity thereof (in the patent document, a joint interpolation range) (in Patent Document, interpolation of the rotation spindle method is performed). Without joint interpolation). However, if tool posture control is not performed, as described above, when a smooth workpiece side surface is processed on the tool side surface, a smooth processed surface cannot be obtained. Since the tool posture is not controlled, a cut is generated on the machined surface.

  Accordingly, an object of the present invention is to provide a 5-axis machine that does not generate a large operation of a rotating shaft capable of making a smooth operation and an end point position as a command position so as not to generate a cutting flaw, in view of the above-described problems of the prior art. A numerical control device is provided.

The invention according to claim 1 of the present application controls a five-axis processing machine that processes a workpiece (workpiece) attached to a table by three linear axes, an inclined rotation axis, and two rotation axes of a turning rotation axis. in the numerical control device, the posture of the tool relative to the workpiece between the two command position command start and command end point, the two said Accordingly direction command position at which the command rotational axis position with respect to the two rotation axes in the command position is There is no movement of the swivel rotation axis between the two command positions and the tool attitude control unit that controls the rotation axis position and the linear axis position so that the rotation axis position and the linear axis position exist on a plane or a smooth surface including the commanded tool attitude. singularity pass judgment to determine that when the command of the inclined rotary shaft across the singularity is a position of the tilt rotary shaft to become stable is opposite should exceed vital passing through the singular point If, when it is determined that it is necessary to exceed vital passing through the singular point at the singular point passing determination unit, and the singularity passing path which the tool orientation exceeds vital pass through the singular point and the two command position 5 is a numerical control device for a 5-axis processing machine provided with a singular point passage route creating unit.

The invention according to claim 2 is a numerical control for controlling a five-axis processing machine for processing a workpiece (workpiece) attached to a table by three axes of a linear axis, an inclined rotation axis, and a rotary axis of rotation. In the apparatus, the rotation axis position and the tool posture with respect to the workpiece between the two command positions of the command start point and the command end point exist on a plane or a smooth surface including the tool posture by the vector command at the two command positions. Minimum distance or minimum between a tool attitude control unit that controls the position of the linear axis, a plane or a smooth surface including the tool attitude, and a singular point that is the position of the tilt rotation axis at which the operation of the swivel rotation axis becomes unstable a singular point passing determination unit for determining that when the angle is smaller than the set value must exceed vital passing through the singular point, only pass through the singular point at the singular point passing determination unit If it is determined that it is necessary to exceed the numerical for 5 axis machine with a singular point passing route creating unit for a singular point passing path which the tool orientation exceeds vital pass through the singular point and the two command position It is a control device.

  According to a third aspect of the present invention, the singular point passage path creation unit creates the path so as to connect to the direction of change of the tool posture to the command start point at the command start point. This is a numerical control device for a shaft machine.

  According to a fourth aspect of the present invention, the singular point passage route creation unit creates a route so as to connect to a change direction of the tool posture from the command end point at the command end point. 5 is a numerical control device for a 5-axis processing machine.

  The invention according to claim 5 is the numerical control device for a 5-axis machining apparatus according to any one of claims 1 to 4, wherein the singular point passage path is created as a command path function representing a tool posture direction. is there.

  The invention according to claim 6 is the numerical control device for a 5-axis machining apparatus according to any one of claims 1 to 4, wherein the singular point passage path is created as a command path function based on a rotation axis position. .

The invention according to claim 7, when the command path such tool attitude by the singular point passing route creating unit exceeds vital pass through the singular point and the two command position is created, the tool posture control unit, In the calculation for obtaining the tool posture vector representing the tool posture for each sampling period and obtaining the position of the two rotation axes from the tool posture vector, the swivel rotation axis in the immediately preceding sampling period in the two sets of solutions obtained The numerical control device for a 5-axis machining apparatus according to claim 5, wherein a solution close to the position of is selected.

According to an eighth aspect of the present invention, the singular point passage path creation unit represents a command path to be created when a command path is created so that the tool posture passes through and exceeds the two command positions and the singular point. The singular point passing path creation unit that obtains a command path function and obtains a singular point parameter value as a parameter of the command path function at the singular point, and the tool posture control unit In the calculation for obtaining the tool posture vector by the parameter and obtaining the position of the two rotation axes from the tool posture vector, when the parameter exceeds the singular point parameter value, The numerical control device for a 5-axis machining apparatus according to claim 5, wherein the set is changed.
According to a ninth aspect of the present invention, in the 5-axis machining apparatus in which the position of the tilt rotation axis is 0 degree is the singular point, the singular point passage determination unit includes the tilt between the two command positions. When the sign of the rotating shaft command is reversed, it is determined that the tilted rotating shaft command is on the opposite side across the singular point between the two command positions and needs to pass and exceed the singular point. The numerical control device for a five-axis machine tool according to claim 1, wherein the singularity passage determination unit is configured to perform the singular point passage determination unit.
According to a tenth aspect of the present invention, in the five-axis machining apparatus in which the position where the tilt rotation axis is not 0 degrees is the singular point, the singular point passage determination unit is configured to move the tilt between the two command positions. When the signs of (command start point-singular point) and (command end point-singular point) are reversed with respect to the command of the rotation axis, the command of the tilt rotation axis is opposite between the two singular points. 2. The numerical control device for a 5-axis machining apparatus according to claim 1, wherein the numerical control device is a singularity passage determination unit that determines that it is necessary to pass through and exceed the singularity.

  According to the present invention, it is possible to perform a smooth operation so as not to generate a cut-in flaw, to obtain a smooth machining surface by machining a workpiece smoothly, and to make the end point position a command position, and the tool can be a machine part, etc. It is possible to provide a numerical control device for a 5-axis machine that can prevent the possibility of collision (interference) and can reduce the machining time because a large operation of the rotating shaft is not generated.

It is a schematic block diagram of the 5-axis processing machine which processes with the linear axis | shaft 3 axis | shafts and the rotating shaft 2 axis | shaft with respect to the workpiece | work (workpiece) fixed and attached to the table. It is a figure explaining the relationship between the command start point commanded by block N10 at the time of paying attention only to the tool posture of <command example 1>. It is the figure which represented the plane by which the tool attitude | position by the instruction | command of the block N10 of <command example 1> is anticipated to operate | move with the oblique line plane. It is a figure showing the smooth surface by which the tool posture by the command of block N10 of <command example 1> is expected to operate. It is a figure explaining operation | movement of a tool attitude | position at the time of selecting the solution close | similar to the last A-axis and C-axis position among 2 sets of solutions. FIG. 4 is a diagram for explaining that the tip of a tool posture vector is interpolated and changed when the same command as in FIG. 3 is commanded with a tool posture vector. The angle θcs between the intermediate point tool posture vector Vc (Vcx, Vcy, Vcz) and the singular point tool posture vector Vsi (0, 0, 1), the intermediate point tool posture vector Vc (Vcx, Vcy, Vcz) and the singular point tool It is a figure explaining distance Lcs of vector tip position with posture vector Vsi (0, 0, 1). It is a figure explaining the singular point passage route in the case of a rotation axis position command. It is a figure explaining the singular point passage course in the case of a tool posture vector command. It is a figure explaining connecting a change of a tool posture to a change direction of a tool posture to a command start point and a change direction of a tool posture from a command end point. N (Nx, Ny, Nz), which is a command path function representing a tool posture vector, is a path that passes through the command start point, command end point, and singular point while the change in tool posture is connected when the tool posture is the command start point and command end point. It is a figure explaining what is calculated | required. Connect D (A, C), which is a command path representing the tool posture, to the command start point, the command end point, and the singular point, and to the tool posture change direction to the command start point and to the tool posture change direction from the command end point. FIG. When the tool posture moves on the plane shown in FIG. 3 from the command start point (A-20, C30) to the command end point (A20, C-30), solutions A and B are obtained as solutions Ac and Bc. It is illustrated. It is the figure which drawn the tool posture vector by solution Ac in FIG. 13 from the Z plus direction. The tool posture vector Vt (Vtx, Vty, Vtz) is obtained from the command path function N (Nx, Ny, Nz), the solutions A and B are obtained from Vt, and these are superimposed on FIG. 13 as the solutions An and Bn. It is. It is the figure which drawn the tool posture vector front-end | tip at the time of transfering from solution An to solution Bn so that it may exceed a singular point from the Z plus direction. FIG. 14 is a diagram in which a command path function D (A, C) is displayed superimposed on the graph of FIG. 13. It is the figure which computed the tool posture vector front-end | tip with respect to instruction | command path | route function D (A, C), and was drawn from the Z plus direction. It is a functional block diagram of the numerical control device for a 5-axis machine of the present invention. It is a functional block diagram of the numerical controller for a 5-axis machine that performs the first interpolation and the second interpolation of the present invention. It is a flowchart which shows the algorithm of a process of the singular point passage judgment part and singular point passage route creation part of this invention. It is a flowchart which shows the algorithm of a process in the case of interpolating the singular point passage route produced | generated by the singular point passage route creation part of this invention by the tool attitude | position control part linked | related with the interpolation part. 1 is a 5-axis processing machine that processes a workpiece (workpiece) fixed and attached to a table with A = 90 degrees by using three linear axes and two rotational axes. It is a schematic block diagram. It is a flowchart which shows the algorithm of the process of the singular point passage judgment part of this invention, and a singular point passage route creation part in the 5-axis processing machine whose position where an inclination rotation axis position is not 0 degree | times is a singular point.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the specification of the present application, the head rotating type 5-axis processing machine shown in FIG. 1 will be described as an example. In FIG. 1, the two rotation axes are A and C axes, but there are also five-axis processing machines in which the B and C axes and the A and B axes are the two rotation axes. Further, as described above, there are table rotating type and mixed type 5-axis processing machines. Since these five-axis machines are the same in terms of controlling the tool posture (relative posture of the tool with respect to the workpiece), the present invention can be applied.
The present invention relates to a numerical control apparatus for controlling a 5-axis processing machine for processing a workpiece (workpiece) attached to a table by two rotation axes of a linear axis, an inclined rotation axis, and a turning rotation axis. Tool posture control for controlling the rotation axis position and the linear axis position so that the tool posture with respect to the workpiece at the two command positions of the start point and the command end point exists on a plane or a smooth surface including the tool posture at the two command positions. A singularity passage determination unit that determines that it is necessary to pass a singular point between the two command positions, and a singular point passage determination unit that determines that it is necessary to pass a singular point. Is a numerical control device for a 5-axis machine, which includes a singular point passage path creation unit that creates a command path so that the tool posture passes through the two command positions and the singular point.

Here, the singularity passage determination will be described.
First, singularity passage determination in the case of the rotation axis position command will be described.
When the tool posture is commanded at the position of the rotation axis (A axis, C axis), when the sign of the tilt rotation axis command of the two rotation axes is reversed between the two command positions of the command start point and the command end point, Judge that it is necessary to pass the singularity. In FIG. 2, since the command start point is A axis −20 degrees and the command end point is A axis 20 degrees, it is determined that the sign of the tilt rotation axis command is reversed and it is necessary to pass through a singular point. In addition, it is considered that the sign of the previous command is continued at 0 degree. For example, when the command start point is A axis −20 degrees and the command end point is A axis 0 degrees, the sign is not considered to be reversed.
However, the above description is a case where A = 0 degree is a singular point. As described in the paragraph “0011”, the state of FIG. 23 is A = 0 degree and the state of FIG. 1 is A = 90 degree. There is also a machine configuration that is.
Furthermore, the singular point is not A = 0 degrees or 90 degrees, and may be at other angles. In such a 5-axis machine, attention is paid to whether or not the signs of (command start point−singular point) and (command end point−singular point) are reversed with respect to the tilt rotation axis (A axis). That is, with respect to the tilt rotation axis (A axis), if the signs of (command start point-singular point) and (command end point-singular point) are reversed, the tilt rotation axis command is on the opposite side across the singular point. Judge that it is necessary to pass through. With respect to the tilt rotation axis (A axis), in the case of a command to a singular point, it is the same as described above that the singular point is not considered to be on the opposite side.

Next, singular point passage determination in the case of a vector command will be described.
When the tool posture is instructed by a tool posture vector, it is determined that it is necessary to pass a singular point when the above-described Equation 3 or Equation 4 is satisfied.

  Next, creation of a singular point passage route when it is determined that it is necessary to pass a singular point in the singular point passage determination will be described. When it is determined that it is necessary to pass the singular point, the command path is changed so that the tool posture passes the command start point, the command end point, and the singular point, and interpolation is performed so that the tool posture exceeds the singular point. Interpolation will be described later. In the example shown in FIG. 2, the present invention changes to a path passing through a singular point as shown in FIG. The same applies when the tool posture is commanded as a vector. The path at the tip of the tool posture vector is changed to a path that passes through a singular point as shown by the dotted line in FIG. 9, and interpolation is performed so that the tool posture exceeds the singular point. Compared with FIG. 6 before the change, it is easy to understand the route change. Interpolation will be described later.

  Further, the tool posture is changed such that the tool posture is connected to the change direction of the tool posture to the command start point and the change direction of the tool posture from the command end point at the command start point and the command end point. That is, as shown in FIG. 10, the change in the tool posture is connected to the command start point in the tool posture change direction from the command end point.

  In FIG. 10, the tool posture is changed so as to be connected to the change direction of the tool posture to the command start point and the change direction of the tool posture from the command end point, but the change direction of the tool posture to the command start point and the tool from the command end point If it is not necessary to connect in the direction of change in posture, the tool path may simply be a command start point, a command end point, and a singular point. Further, when the change direction of the tool posture from the command end point is not yet known, it is only necessary to change the tool posture so as to connect to the change direction of the tool posture to the command start point.

  As shown in FIGS. 8 to 10, by creating a singular point passage, a smooth machined surface with no cuts on the machined surface is obtained. Moreover, since a large operation does not occur, the processing time is short. Furthermore, the end point position becomes a command position.

Next, an example of obtaining a command path function representing a command path of a tool posture will be described.
FIG. 11 shows a command start point, a command end point, and a singular point while N (Nx, Ny, Nz), which is a command path function representing the tool posture direction, is connected with changes in the tool posture at the command start point and the command end point. It is a figure explaining calculating | requiring as a path | route which passes through.

  When the tool posture is commanded by a rotation axis position command or a vector command, a command path function representing the tool posture direction is obtained. Further, the function is interpolated with parameters, and the rotation axis positions of the A axis and the C axis are obtained from the obtained tool posture vector. The A-axis and C-axis servos are controlled according to the obtained A-axis and C-axis positions. Here, N (Nx, Ny, Nz) is a command path function representing the tool posture direction in the X, Y, Z coordinate system, and when this is normalized, it becomes a tool posture vector.

In the following manner, N (Nx, Ny, Nz) is obtained as a path passing through the command start point, the command end point, and the singular point while the change in the tool posture is connected when the tool posture is the command start point and the command end point. Ns is the tool posture vector at the command start point, Ns ′ is the tangential direction of the tool posture change at the command start point (the change direction of the tool posture to the command start point), Nc is the tool posture vector at the singular point, and Ne is the tool posture vector at the command end point , Ne ′ is the tangential direction of the tool posture change at the command end point (the tool posture change direction from the command end point).
Ns, Ns ′, Nc, Ne, Ne ′ are given, and the command path function N (Nx, Ny, Nz) is obtained as a function representing a smooth curve such as a polynomial, a spline function, or a NURBS function. When N (Nx, Ny, Nz) is normalized, a tool posture vector Vt (Vtx, Vty, Vtz) is obtained. When it is not necessary to connect a change in tool posture at the command start point or command end point, the conditions to be given are reduced and the order of the function is reduced.

  For example, the case where the command path function N (Nx, Ny, Nz) is expressed by a function of a fourth-order polynomial of the parameter t as follows is shown.

E, F, G, H, and J are three-dimensional (X, Y, Z) coefficient vectors, respectively.
If five conditions of Ns, Ns ′, Nc, Ne, Ne ′ are given, five coefficients of E, F, G, H, and J can be calculated. As a result, the command path function N (Nx, Ny, Nz) can be obtained.

  While changing the parameter t for each sampling period, N (Nx, Ny, Nz) is calculated and normalized to obtain a tool attitude vector Vt representing the tool attitude for each sampling period. When the A-axis and C-axis positions are obtained from the tool attitude vector Vt, normally two sets of solutions (solution A and solution B) are obtained as described above (see Equation 1 and Equation 2). The command path function N (Nx, Ny, Nz) is obtained as a function representing a path passing through the singular point. To exceed the singular point as the A-axis and C-axis positions, the solution A from the solution A before or after the singular point or its solution B On the contrary, after the singularity, it is necessary to change from the solution set before the singularity to another solution set. A method for this is described.

(1) Selection of a solution close to the immediately preceding turning axis The position of the turning axis (C axis) is always close to the position of the turning axis (C axis) at the immediately preceding sampling period in the current sampling period. Select a solution. Since N (Nx, Ny, Nz) changes smoothly, it does not change rapidly even near the singular point. For this reason, a solution that does not change rapidly, that is, a solution close to the position of the rotation axis (C axis) in the immediately preceding sampling period is selected in the current sampling period.

(2) Method by singular point parameter value For the command path function, a singular point parameter value is obtained as a parameter at the singular point. Substituting a singular point into Equation 5 to solve it, and let t be ts. That is, ts is obtained as shown in Equation 6.

  When the command path function is calculated from the parameter t for each sampling period to obtain the tool posture vector, the A-axis and C-axis positions are obtained from the tool posture vector, the solution is obtained when the parameter t exceeds the singular point parameter ts (t> ts). Change the pair. That is, after the singular point, the solution set before the singular point is changed to another solution set, such as the solution A to the solution B or vice versa. As a result, the positions of the A axis and the C axis exceeding the singular point can be obtained. The A-axis and C-axis servos are driven according to the obtained A-axis and C-axis positions. A specific method for interpolating the command path function and obtaining the A-axis and C-axis positions will be described later together with a simulation example.

A case of a function of the rotation axis position will be described.
FIG. 12 shows a command path function D (A, C) representing a tool posture, a command start point, a command end point, a singular point, a change direction of the tool posture to the command start point, and a tool posture change from the command end point. It is a figure explaining connecting in a direction.

  When the tool posture is commanded by the rotation axis position command, paying attention to the operation of the rotation axis, the direction of change of the tool posture from the command start point to the command start point passing through the command start point, command end point and singular point, and the tool posture change from the command end point Interpolate by finding the command path function connected in the direction. The A-axis and C-axis servos are driven according to the A-axis and C-axis positions obtained by interpolation.

  Here, D (A, C) is a command path function indicating the tool posture. (A, C) means a function based on the A-axis and C-axis positions. D is obtained as follows, passing through the command start point, the command end point, and the singular point, and connecting the tool posture change direction to the command start point and the tool posture change direction from the command end point. Ds is the command start point, Ds ′ is the tangential direction at the command start point (the tool orientation change direction to the command start point is converted to the A-axis and C-axis directions), De is the command end point, and De ′ is the tangential direction at the end point. (The change direction of the tool posture from the command end point is converted to the A-axis and C-axis directions).

  Ds, Ds ′, De, and De ′ are given, and a command path function D (A, C) indicating the tool posture is obtained as a function representing a smooth curve such as a polynomial, a spline function, or a NURBS function. In this case, since it always passes through the singular point (A = 0), the condition for passing through the singular point Nc when N is obtained is unnecessary. If it is not necessary to connect in the direction of change of the tool posture at the command start point or command end point, the condition to be given may be reduced and the order of the function may be reduced. For example, a case where the command path function D (A, C axis) is expressed by a function of a third-order polynomial of the parameter t as follows is shown.

Here, P, Q, R, and S are two-dimensional (A, C) coefficient vectors, respectively.
If four conditions of Ds, Ds ′, De, and De ′ are given, four coefficients of P, Q, R, and S can be calculated. As a result, the command path function D (A, C) can be obtained.

  While changing the parameter t for each sampling period, D (A, C) is calculated to obtain the A-axis and C-axis positions for each sampling period. The A-axis and C-axis servos are driven according to the obtained A-axis and C-axis positions. A specific method for interpolating the command path function to obtain the A-axis and C-axis positions will be described later along with a simulation example.

  Next, a description will be given of the result of a simulation for obtaining the A-axis and C-axis positions in the command example 1 of FIG. When the tool posture changes on the plane indicated by the command end point (A20, C-30) from the command start point (A-20, C30), a solution A and a solution B are obtained and shown as a solution Ac and a solution Bc in FIG. As described with reference to FIG. 5, when a solution close to the A-axis and C-axis positions immediately before the solutions A and C are obtained is assumed that the solution A is close to the immediately preceding rotation axis position at the command start point, As shown in “Change of solution Ac” in FIG. 13, solutions of A and C are obtained. This is the case (3) described as the problem of the prior art. Therefore, the command end point is not reached. FIG. 14 shows the tool posture vector based on the solution Ac at this time when drawn from the Z plus direction. FIG. 14 corresponds to FIG.

When commanded as in command example 1 in FIG. 2, command path function N (Nx, Ny, Nz) that passes through the singular point described in Equation 5 (parameter t is 0 to 1 between command start point and command end point) ). Here, Ns and Ne are obtained as follows by converting the commands for the A-axis and C-axis at the command start point and the command end point in FIG. 2 into the tool posture direction. The singular point is Nc = (0, 0, 1). This N is the same when the tool posture direction is commanded by the tool posture vector as in command example 2 of FIG.
Ns = (− 0.171, 0.296, 0.94)
Ne = (− 0.171, −0.296, 0.94)

Assume that Ns ′ and Ne ′ are given as follows. This is obtained by converting the change direction when the tool posture changes in the direction on the plane at the command start point and the command end point in the plane of FIG. 3 into the change direction of the tool posture direction. In FIG. 15, the vector at the command start point and the command end point is also entered.
Ns ′ = (− 0.053, −0.955, 0.291)
Ne ′ = (0.053, −0.955, −0.291)

From now on, when the command path function N (Nx, Ny, Nz) is obtained by the method described in the explanation of Expression 5, each coefficient is as follows.
E = (2.948, 0.0, −0.201)
F = (− 5.897, −0.725, 0.401)
G = (3.001, 1.088, -0.492)
H = (− 0.053, −0.955, 0.291)
J = (− 0.171, −0.296, 0.94)
When the result N (Nx, Ny, Nz) is normalized to obtain a solution A and a solution B as a tool posture vector Vt (Vtx, Vty, Vtz), which are superimposed on FIG. 13 as a solution An and a solution Bn. As shown in FIG.

  Ns ′ and Ne ′ are drawn with the vector length changed in terms of the A axis and the C axis. Here, it is necessary to change the selection of the solution from the solution An to the solution Bn in the portion marked with “exceeding the singular point” with a circle, and thereby the A-axis and C-axis positions exceeding the singular point are obtained. Although the method of exceeding the singular point has been described above, it will be described more specifically.

(1) Interpretation of a solution close to the immediately preceding turning axis As described above, with respect to the position of the turning axis (C axis) in the immediately preceding sampling cycle, the position of the turning axis (C axis) is In the sampling period, a solution that is always close to the position of the rotation axis (C axis) in the immediately preceding sampling period is selected. In the above example, N (Nx, Ny, Nz) is obtained and normalized to obtain the tool posture vector Vt (Vtx, Vty, Vtz), and the A axis and C axis positions when the solutions An and Bn are calculated pass singular points. It changes as shown in Table 1 before and after this part. A and C are expressed in degrees.

  The solution An is selected immediately before the singular point. However, if the solution An is continuously selected, a large movement (0 → 175.07) occurs on the C axis from the singular point to immediately after the singular point. If the singular point is the solution An and the solution Bn is selected immediately after the singular point, the movement of the C axis (0 → −4.928) is small. Therefore, the solution Bn is selected immediately after the singular point.

(2) Method by singular point parameter value For the command path function, a singular point parameter value is obtained as a parameter at the singular point. That is, ts is obtained by the equation (6). In the above example, ts = 0.5. In Table 1, the parameter t changes from 0.475 → 0.5 → 0.525 immediately before the singular point to immediately after the singular point for each sampling period. When the parameter t exceeds the singular point parameter ts (t> ts), the solution set is changed. Therefore, the solution An is selected up to the singular point, and the solution Bn is selected immediately after the singular point.

  By these methods, the positions of the A axis and the C axis exceeding the singular point are obtained. When the tip of the tool posture vector is drawn from the Z plus direction when moving from the solution An to the solution Bn so as to exceed the singular point, it becomes as shown in FIG. 16 and passes through the singular point (0, 0, 1). The path of the tool posture vector tip in FIG. 16 corresponds to the operation of the machine control point in FIG.

When commanded as in command example 1 in FIG. 2, command path function D (A, C) passing through the singular point described in Equation 7 (parameter t changes from 0 to 1 between command start point and command end point) Then ask). Here, from the commands for the A-axis and C-axis in FIG.
Ds = (− 20, 30) (degree) = (− 0.349, 0.524) (radian)
De = (20, −30) (degrees) = (0.349, −0.524) (radians)
Assume that Ds ′ and De ′ are given as follows. This is obtained by converting the direction of change when the tool posture changes in the direction on the plane at the command start point and the command end point in the plane of FIG. 3 into the directions of the A axis and the C axis. That is, it is equivalent to Ns ′ and Ne ′. In FIG. 17, the tangent direction at the command start point and the command end point is also entered.
Ds ′ = (0.852, 1.531) (radian)
De ′ = (0.852, 1.531) (radian)
From this, when the command path function D (A, C) is obtained by the method described in the explanation of Expression 7, each coefficient is as follows.
P = (0.308, 5.156)
Q = (− 0.462, −7.733)
R = (0.852, 1.531)
S = (− 0.349, 0.524)
When the resultant D (A, C) is superimposed on FIG. 13, the result is shown in FIG. Since D (A, C) is uniquely determined as a polynomial with respect to t, it does not have two sets of solutions A and B. By calculating D (A, C) while changing the parameter t for each sampling period, the A-axis and C-axis positions for each sampling period are obtained.

  At that time, when the tool posture vector tip is calculated with respect to D (A, C) and drawn from the Z plus direction, it becomes as shown in FIG. 18, and the singular point (0, 0, 1) is shown as shown in FIG. Has passed. The tool tip vector path in FIG. 18 corresponds to the dotted path in FIG.

  Here, the command start point and the command end point in FIG. 2 will be described. The command start point and the command end point may be a program command position commanded by a program or a first interpolated position.

  FIG. 19 is a functional block diagram of the numerical controller according to the present invention in the case of the program command position. In general, the numerical control device analyzes each block command of the program command by the command analysis unit 10, performs interpolation by the interpolation unit 11, and drives each axis servo 12X,. When performing the tool posture control, the tool posture control unit 15 associated with the interpolation unit 11 performs the tool posture control so that the tool posture is operated on the commanded or smooth surface.

  When the command start point and command end point are the block start point and block end point commanded by the program, the singular point passage determination unit 13 and the singular point passage route creation unit 14 are associated with the command analysis unit 10 and command the block start point and block end point. Singular point passage judgment and singular point passage route creation are performed as the start point and command end point. The tool posture control unit 15 is associated with the interpolation unit 11 and performs tool posture control by interpolating the created singular point passage.

  FIG. 20 is a functional block diagram of a numerical controller that analyzes each block command of the program command by the command analysis unit 20, performs the first interpolation roughly in the first interpolation unit, and then performs the second interpolation finely. In this case, the singular point passage determination unit 25, the singular point passage route creation unit 26, and the tool posture control unit 27 are associated with the first interpolation unit 21 that performs the first interpolation, and the second interpolation unit 23 also includes The tool posture control unit 27 is associated.

  The interpolation position of the first interpolation that has been subjected to the tool posture control at each sampling period of the first interpolation is set as the command start point and the command end point, and the singular point passage determination unit 25 passes through the command start point and the command end point position. If the singular point passage is determined, the singular point passage route creation unit 26 changes the interpolation position of the first interpolation to the singular point passage route, and sets the changed singular point passage route in the intermediate memory 22. The second interpolation unit 23 that performs interpolation at a finer sampling period interpolates the singular point passage based on the set data in the intermediate memory 22 and performs tool posture control. In this case, the sampling period of claims 5 and 6 is a sampling period of the second interpolation. Further, “interpolation” described in other paragraphs of the present specification means processing in the second interpolation and processing in the tool posture control unit 27 associated with the second interpolation.

FIG. 21 is a flowchart showing the processing algorithm of the singularity passage determination unit and the singularity passage route creation unit of the present invention. However, it is a flowchart when A = 0 degree is a singular point. FIG. 21 shows that the command start point and command end point are the block start point and block end point specified by the rotation axis position command in the program, and the singular point passage determination unit and the singular point when the command path is changed as a function of the tool posture direction. The point passage route creation unit is shown in a flowchart. Hereinafter, it demonstrates according to each step.
[Step SA1] Obtain the command start point and command end point.
[Step SA2] It is determined whether or not the sign of the tilt rotation axis is reversed at the command start point and the command end point. If the sign of the tilt rotation axis is reversed, the process proceeds to Step SA3.
[Step SA3] The command path function N of Formula 5 is obtained from the conditions of Ns, Ne, Nc, Ns ′, and Ne ′. The singularity parameter value ts is obtained from Equation 6 and the processing is completed. Steps SA1 and SA2 correspond to a singular point passage determination unit, and step SA3 corresponds to a singular point passage route creation unit.

FIG. 22 is a flowchart showing a processing algorithm when the singular point passage route created by the singular point passage route creation unit of the present invention is interpolated by the tool posture control unit associated with the interpolation unit. Hereinafter, it demonstrates according to each step. Here, it is assumed that the solution A is close to the immediately preceding rotation axis position at the command start point.
[Step SB1] The command path function N is calculated with the parameter t. Here, it is assumed that t has already been calculated by the interpolation unit as a value that changes from 0 to 1 between the command start point and the command end point. N is normalized to obtain a tool posture vector Vt (Vtx, Vty, Vtz). A solution An and a solution Bn are obtained from Vt by Equation 1 and Equation 2.
[Step SB2] It is determined whether t is equal to or less than ts. If it is equal to or less, the process proceeds to Step SB3, and if not, the process proceeds to Step SB4.
[Step SB3] The solution An is selected, and the A and C axis interpolation positions based on the solution An are set.
[Step SB4] The solution Bn is selected, and the A and C axis interpolation positions based on the solution Bn are set.

FIG. 24 is a flowchart showing an algorithm of processing of the singular point passage determination unit and the singular point passage route creation unit of the present invention in a 5-axis machine with a singular point where the tilt rotation axis position is not 0 degrees. The command start point and command end point are the block start point and block end point specified by the rotation axis position command in the program, and the singular point passage determination unit and singular point passage route creation unit when changing the command path as a function of the tool posture direction Are shown in a flowchart. Hereinafter, it demonstrates according to each step.
[Step SAA1] Obtain the command start point and command end point.
[Step SAA2] Regarding the tilt rotation axis, it is determined whether or not the signs of (command start point-singular point) and (command end point-singular point) are reversed. If the signs are reversed, the process proceeds to step SAA3 and reversed. If not, exit.
[Step SAA3] The command path function N of Formula 5 is obtained from the conditions of Ns, Ne, Nc, Ns ′, and Ne ′. The singularity parameter value ts is obtained from Equation 6 and the processing is completed. Step SAA1 and step SAA2 correspond to a singular point passage determination unit, and step SAA3 corresponds to a singular point passage route creation unit.

DESCRIPTION OF SYMBOLS 10 Command analysis part 11 Interpolation part 12X X-axis servo 12Y Y-axis servo 12Z Z-axis servo 12A (B) A (B) axis servo 12C C-axis servo 13 Singularity passage judgment part 14 Singularity passage path creation part 15 Tool attitude control Unit 20 Command analysis unit 21 First interpolation unit 22 Intermediate memory 23 Second interpolation unit 24X X-axis servo 24Y Y-axis servo 24Z Z-axis servo 24B (A) B (A) -axis servo 24C C-axis servo 25 Singularity passage determination unit 26 Singularity passing path creation unit 27 Tool posture control unit

Claims (10)

In a numerical control device for controlling a 5-axis processing machine that processes a workpiece (workpiece) attached to a table by two rotation axes of a linear axis, an inclined rotation axis, and a turning rotation axis,
Orientation of the tool relative to the workpiece between the two command position command start and command end point, tool posture wherein two of said command position in which the command rotational axis Accordingly direction position relative to the two rotation axes in the command position is commanded A tool attitude control unit that controls the rotation axis position and the linear axis position so that they exist on a plane or smooth surface including
Between said two command position, the case where the command of the tilt rotary shaft turning operation of the rotation axis is a position of the tilt rotary shaft unstable across the singularity is opposite to the singularity A singularity passage determination unit that determines that it is necessary to pass and exceed
If it is determined that it is necessary to exceed vital passing through the singular point at the singular point passing determination unit, specific to a singular point passing path which the tool orientation exceeds vital passes through the two command position and the singular point A numerical control device for a 5-axis machine, comprising a point passing path creation unit. In a numerical control device for controlling a 5-axis processing machine that processes a workpiece (workpiece) attached to a table by two rotation axes of a linear axis, an inclined rotation axis, and a turning rotation axis,
Rotation axis position and linear axis position so that the tool posture with respect to the workpiece between the two command positions of the command start point and the command end point exists on a plane or a smooth surface including the tool posture by the vector command at the two command positions A tool attitude control unit for controlling
Plane or smooth surface and the case where the minimum distance or minimum angle between the singular point is a position of the tilt rotary shaft operation of pivoting the rotating shaft becomes unstable is smaller than the set value the singular point comprising said tool attitude A singularity passage determination unit that determines that it is necessary to pass and exceed
If it is determined that it is necessary to exceed vital passing through the singular point at the singular point passing determination unit, specific to a singular point passing path which the tool orientation exceeds vital pass through the singular point and the two command position A numerical control device for a 5-axis machine, comprising a point passing path creation unit.   3. The numerical control device for a 5-axis machining apparatus according to claim 1, wherein the singular point passage route creation unit creates a route so as to be connected to a change direction of a tool posture to the command start point at the command start point.   The 5-axis processing machine according to any one of claims 1 to 3, wherein the singular point passage route creation unit creates a route so as to connect to a change direction of a tool posture from a command end point at the command end point. Numerical controller.   The numerical control device for a 5-axis machining apparatus according to any one of claims 1 to 4, wherein the singular point passing path is created as a command path function representing a tool posture direction.   The numerical control device for a 5-axis machining apparatus according to any one of claims 1 to 4, wherein the singular point passage path is created as a command path function based on a rotation axis position. When commanded path to tool attitude exceeds vital pass through the singular point and the two command position by the singular point passing route creating unit is created, the tool posture control unit, the tool posture of each sampling period In a calculation for obtaining a tool posture vector to be expressed and obtaining the position of the two rotary shafts from the tool posture vector, a solution close to the position of the swivel rotary shaft in the immediately preceding sampling cycle is selected from the two obtained solutions. The numerical control device for a 5-axis machining apparatus according to claim 5. The singular point passing route creating unit, when the tool posture to create a commanded path to exceed vital pass through the singular point and the two command position, the singular point seek command path function representing a command path for the created The singularity passing path creation unit for obtaining a singularity parameter value as a parameter of the command path function in
The tool posture control unit obtains a tool posture vector from the command path function and a parameter for each sampling period, and calculates the position of the two rotation axes from the tool posture vector. The parameter exceeds the singular point parameter value. 6. The numerical control device for a 5-axis machining apparatus according to claim 5, wherein a set of solutions selected from the two sets of solutions obtained is changed. In the 5-axis processing machine in which the position of the tilt rotation axis is 0 degree is the singular point, the singular point passage determination unit reverses the sign of the command of the tilt rotation axis between the two command positions. The singularity passage determination unit that determines that the command of the tilt rotation axis is opposite to the singularity and needs to pass and exceed the singularity between the two command positions. The numerical control device for a 5-axis machining apparatus according to claim 1 . In the 5-axis machining apparatus in which the position of the tilt rotation axis is not 0 degrees is the singular point, the singular point passage determination unit is configured to provide a command for the tilt rotation axis between the two command positions (command start point). -When the signs of (singular point) and (command end point-singular point) are reversed, the command of the tilt rotation axis is on the opposite side across the singular point between the two command positions and passes through the singular point The numerical control device for a 5-axis machining apparatus according to claim 1, wherein the singularity passage determination unit determines that it is necessary to exceed.

Images