JP4607993B2 - Numerical control method of 5-axis machine - Google Patents

Description

  A numerical control method for controlling a 5-axis machine having two rotary axes and three linear axes, and relates to operation control in the vicinity of a singular point that may cause unstable operation.

A 5-axis machine that performs machining by moving a tool relative to a workpiece (workpiece) in a linear three-axis direction and tilting the tool relative to the workpiece in a two-axis rotation axis is already known. .
For example, a machining method using a 5-axis machining machine that performs curved surface interpolation to process a curved surface based on command point sequence data created by a CAD / CAM device or a copying device and a command vector sequence that commands the tilt angle of a workpiece and a tool The machining method is known in which a smooth curved surface close to the intended curve is interpolated to obtain a smooth machined surface (see Patent Document 1).

  Also, in a 5-axis machine, when the tool position and orientation are commanded on the Cartesian coordinate system fixed to the work target and the tool is moved at a certain speed, a singular point (singular posture) within the operating range of the machine In some machines, the speed and acceleration of each joint may exceed the allowable values for that joint. Therefore, based on the posture at two points given to the tool, the tool posture error between the two points The joint interpolation range is determined so that is less than the posture error allowable value. In this joint interpolation range, joint interpolation (interpolation for obtaining joint coordinate values of each axis based on the position vector and posture vector at two points in time) By controlling the posture of the tool, the speed and acceleration of each joint near the singular point will be excessive, and the moving speed will be shortened as much as possible while satisfying the required accuracy for the trajectory error. Inventions are also known (see Patent Document 2).

JP 2005-182437 A JP 2004-220435 A

A cutting point for machining a workpiece with a tool is different from a control point for controlling a tool position with respect to the workpiece.
FIG. 1 shows a case where a ball end mill is used as a tool 1 in a 5-axis processing machine having three linear axes of X, Y, and Z axes, a rotation axis A axis around the X axis, and a C axis around the Z axis. It is explanatory drawing of the relationship between the commanded cutting point and the tool position controlled.
As the cutting points, the positions (X, Y, Z) of the X, Y, and Z axes in the orthogonal coordinate system corresponding to the X, Y, and Z axes of the linear axes are commanded. For such a cutting point command (X, Y, Z), the control point for controlling the position of the tool 1 with respect to the workpiece is not a point that contacts the workpiece at the tip of the tool 1 (cutting point command point), The linear axis position (Xc, Yc, Zc) is far from the position, and the commanded cutting point position (X, Y, Z) does not match the corresponding linear axis position (Xc, Yc, Zc). Cutting surface vertical direction command (I, J, K) commanded together with cutting point position (X, Y, Z) and tool radius correction determined by set tool radius correction amount TR, and rotation of A axis and C axis The tool length is corrected by the tool direction obtained from the command to the axis, the set tool radius correction amount TR, and the tool length correction amount TL, and the linear axis position (Xc, Yc, Zc) is obtained, and the linear axis position (Xc , Yc, Zc) and the rotation axis position (A, C) are controlled.

  As described above, the commanded cutting point position (X, Y, Z) and the position of the tool 1 with respect to the workpiece, that is, the position (Xc, Yc, Zc) of the controlled linear axis do not match. The same applies when using a square end mill that has a rectangular cross-section when the main shaft turns, or a radius end mill with a rounded corner (R) at the corner, other than the ball end mill. The positions of the linear axes do not match.

However, in general, it is desirable that the cutting point command point and the control point operate in the same manner. That is, it is desirable that the operation of the corresponding control point is small if the command interval of the cutting point is small, and the operation of the corresponding control point is large if the command interval of the cutting point is large.
For example, the relationship between cutting points and control points in a general cutting point command in a square end mill is as shown in FIG. As shown in FIG. 2, the tool 1 is determined by the distance between the start point command (XS, YS, ZS) and the end point command (XE, YE, ZE) commanded in one block and the command in the block. It is desirable that the distance between the starting point and the ending point of the control point (Xc, Yc, Zc) of the linear axis that drives is substantially proportional. However, depending on the command shape and the tool type, the operation of the cutting point (command point) and the control point may differ greatly. That is, when the command interval of the cutting point is small but the corresponding control point operates large (as shown in FIG. 9 described later), or when the operation of the corresponding control point is small although the interval of the command cutting point is large ( (A case as shown in FIG. 10 described later) or the like occurs (hereinafter, such a case is referred to as a singular point vicinity).
In the vicinity of the singular point where the operation of the control point corresponding to the cutting point (command point) is greatly different, unstable operation and excessive cutting into the workpiece are undesirable. The present invention is intended to solve such problems.

First, before explaining this problem, the operation and principle of machining control based on a cutting point command that has been conventionally performed by a control device such as a numerical control device that controls a 5-axis machine will be described.
FIG. 3 is an operation explanatory diagram when a ball end mill is used as the tool 1 and the positions of the three linear axes of the XYZ axes and the rotational axis of the AC axis are obtained and controlled from a cutting point command.
In this case, a program as shown in FIG. 4 is used as the machining program.

In FIG. 4, the left side is a machining program and the right side is an explanation of this machining program. “G43.8” is a cutting point command code, “H01” is a tool length correction number “01”, and a command to use the tool length correction amount indicated by the tool length correction number is “D01”. Is a command to use the tool radius correction amount indicated by the tool radius correction number when the tool radius correction number is “01”. Also, “X Y Z A C I J K "Is a cutting point command block" X Y Z "A cutting point command indicating the position of the cutting point on the XYZ axes on the Cartesian coordinate system," A C "Is a tool direction command," I J K "Is a command indicating the direction perpendicular to the cutting surface at the cutting point. “G49” is a command for canceling and ending the machining control by this cutting point command.

  Further, a tool radius correction amount TR, a tool length correction amount TL, and a corner R correction amount CR, which will be described later, are set as parameters for each correction number. FIG. 5 shows an example of setting the tool correction amount. If the corner R correction amount CR is set to “0.0”, it means that there is no corner R and that the tool is a square end mill. If the same value as the tool radius correction amount TR is set in the corner R correction amount CR, the tool means a ball end mill. In the example shown in FIG. 5, the correction number “01” means a ball end mill, the correction number “02” means a radius end mill, and the correction number “03” means a square end mill.

The control device reads the block command (X, Y, Z, A, C, I, J, K) from the machining program, and the read block cutting point command (X, Y, Z) at the end point of the block. The cutting point command (XE, YE, ZE) is used, and the cutting point command (X, Y, Z) in the previous block which is the end point of the previous block is used as the cutting point command (XS, YS, ZS). Similarly, the cutting surface vertical direction command (I, J, K) at the start point of the block read from the program is represented as (IS, JS, KS), and the cutting surface vertical direction command (I, J, K) at the block end point. ) Is represented as (IE, JE, KE).
(1) Interpolation processing is performed at every interpolation cycle from the position of the cutting point command (XS, YS, ZS) at the block start point to the position of the cutting point command (XE, YE, ZE) at the block end point. The position (Xt, Yt, Zt) is obtained.
(2) Similarly, interpolation processing is performed from the cutting surface vertical direction command (IS, JS, KS) at the block start point to the cutting surface vertical direction command (IE, JE, KE) at the block end point for each interpolation cycle, that is, A cutting surface vertical direction interpolation vector (It, Jt, Kt) at the cutting point interpolation position (Xt, Yt, Zt) is obtained. The cutting surface vertical direction interpolation vector (It, Jt, Kt) is obtained as a unit vector.
(3) The tool radius correction vector (TCx, TCy, TCz) is obtained by multiplying the cutting surface vertical direction interpolation vector (It, Jt, Kt) by the tool radius correction amount TR set as a parameter.
(4) The tool direction vector (TSx, TSy, TSz) at the block start point and the tool direction vector (TEx, TEy, TEz) at the block end point are obtained from the tool direction commands A and C at the start point and end point in the read block. . If the tool direction command at the block start point is AS, CS, and the tool direction command at the block end point is AE, CE,
TSx = -cos (CS) sin (AS)
TSy = -sin (CS) sin (AS)
TSz = cos (AS)
TEx = -cos (CE) sin (AE)
TEy = −sin (CE) sin (AE)
TEz = cos (AE)
It is obtained as
(5) A tool direction interpolation vector (Ttx, Tty, Ttz) is obtained by performing interpolation processing from the tool direction vector (TSx, TSy, TSz) at the block start point to the tool direction vector (TEx, TEy, TEz) at the block end point. . This tool direction interpolation vector (Ttx, Tty, Ttz) is also obtained as a unit vector.
(6) The tool length correction vector (TLx, TLy, TLz) is obtained by multiplying the tool direction interpolation vector (Ttx, Tty, Ttz) by the value (TL-TR) obtained by subtracting the tool radius correction amount TR from the tool length correction amount TL. Ask.
(7) The tool diameter correction vector (TCx, TCy, TCz) and the tool length correction vector (TLx, TLy, TLz) are added to the cutting point interpolation position (Xt, Yt, Zt), and the linear axis control point position (Xc , Yc, Zc). This linear axis control point position (Xc, Yc, Zc) is the moving position of the linear axis (X, Y, Z axis) in the interpolation cycle.
(8) The tool direction vector (Ttx, Tty, Ttz) is converted into the rotation axis control point position (Ac, Cc). The converted rotation axis control point position (Ac, Cc) is a position where the rotation axis (A, C axis) for each interpolation period moves.
Ac = arccos (Ttz)
Cc = arctan (Tty / Ttx)
Through the above processing, the linear axis control point position (Xc, Yc, Zc) and the rotation axis control point position (Ac, Cc) for each interpolation cycle are obtained, and the servo that drives each axis to move to this position. Machining is performed by driving and controlling the motor.

FIG. 6 is an explanatory diagram of a process for obtaining the linear axis control point position and the rotation axis control point position by the cutting point command for each interpolation period when the tool 1 is a square end mill. The machining program in this case is equivalent to the machining program shown in FIG. 4, and a tool length correction number (“H03”) and a tool diameter correction number (“D03”) are commanded, and the tool correction amount shown in FIG. In the setting example, the correction number 03 is selected, the corner R correction amount CR is “0.0”, and the square end mill is designated.
(1) The control device reads the block command (X, Y, Z, A, C, I, J, K) from the machining program, and starts from the position of the cutting point command (XS, YS, ZS) at the block start point. Interpolation processing is performed up to the position corresponding to the cutting point command (XE, YE, ZE) at the block end point, and the cutting point interpolation position (Xt, Yt, Zt) is obtained for each interpolation cycle.
(2) Interpolation from the cutting surface vertical direction command (IS, JS, KS) at the block start point to the cutting surface vertical direction command (IE, JE, KE) at the block end point, and cutting surface vertical direction interpolation for each interpolation cycle A vector (It, Jt, Kt) is obtained. The cutting surface vertical direction interpolation vector (It, Jt, Kt) is obtained as a unit vector.
(3) The tool direction vector (TSx, TSy, TSz) at the block start point and the tool direction vector (TEx, TEy, TEz) at the block end point are obtained from the tool direction commands A and C at the start point and end point in the read block. . This method is the same as the method described in (4) of the ball end mill.
(4) A tool direction interpolation vector (Ttx, Tty, Ttz) is obtained by performing interpolation processing from the tool direction vector (TSx, TSy, TSz) at the block start point to the tool direction vector (TEx, TEy, TEz) at the block end point. . This tool direction interpolation vector (Ttx, Tty, Ttz) is also obtained as a unit vector.
(5) The tool direction interpolation vector (Ttx, Tty, Ttz) is rotated by 90 degrees on the plane formed by the tool direction interpolation vector (Ttx, Tty, Ttz) and the cutting surface vertical direction interpolation vector (It, Jt, Kt). A tool radius correction vector (TCx, TCy, TCz) is obtained by multiplying the tool radius correction amount TR. The tool direction interpolation vector (Ttx, Tty, Ttz) is rotated by a cross product vector (Vx, Vy, Kt) of the tool direction interpolation vector (Ttx, Tty, Ttz) and the cutting surface vertical direction interpolation vector (It, Jt, Kt). Vz) is also obtained.

(Vx, Vy, Vz) = (Ttx, Tty, Ttz) × (It, Jt, Kt)
The outer product vector (Vx, Vy, Vz) is a vector perpendicular to the plane formed by the tool direction interpolation vector (Ttx, Tty, Ttz) and the cutting surface vertical direction interpolation vector (It, Jt, Kt). A unit vector (VNx, VNy, VNz) of the outer product vector (Vx, Vy, Vz) is obtained, and a tool direction interpolation vector (Ttx, Tty, Ttz) is 90 around the unit vector (VNx, VNy, VNz). The tool direction interpolation vector (Ttx, Tty, Ttz) rotated 90 degrees is obtained by rotating the tool by 90 degrees. In general, a method of rotating a vector by an angle around a unit vector is described in “Computer Graphics” (translated by DAVID F. ROGERS, J. ALANADAMS by Fujio Yamaguchi).
(6) The tool length correction vector (TLx, TLy, TLz) is obtained by multiplying the tool direction interpolation vector (Ttx, Tty, Ttz) by the tool length correction amount TL.
(7) The tool diameter correction vector (TCx, TCy, TCz) and the tool length correction vector (TLx, TLy, TLz) are added to the cutting point interpolation position (Xt, Yt, Zt), and the linear axis control point position (Xc , Yc, Zc). This linear axis control point position (Xc, Yc, Zc) is the moving position of the linear axis (X, Y, Z axis) in the interpolation cycle.
(8) The tool direction vector (Ttx, Tty, Ttz) is converted into the rotation axis control point position (Ac, Cc). The converted rotation axis control point position (Ac, Cc) is a position where the rotation axis (A, C axis) for each interpolation period moves. This conversion method is the same as that of the ball end mill described above.

  Through the above processing, the linear axis control point position (Xc, Yc, Zc) and the rotation axis control point position (Ac, Cc) for each interpolation cycle are obtained, and the servo that drives each axis to move to this position. Machining is performed by driving and controlling the motor.

FIG. 7 is an explanatory diagram of processing for obtaining the linear axis control point position and the rotation axis control point position by the cutting point command for each interpolation cycle when the tool 1 used is a radius end mill. An example of the machining program in this case is shown in FIG. Although it is equivalent to the machining program shown in FIG. 4, a tool length correction number (“H02”) and a tool radius correction number (“D02”) are commanded, and the correction number 02 in the tool correction amount setting example shown in FIG. Since the corner R correction amount CR is “2.0”, the radius end mill is designated. Others are the same as the example shown in FIG.
(1) The control device reads the block command (X, Y, Z, A, C, I, J, K) from the machining program, and starts from the position of the cutting point command (XS, YS, ZS) at the block start point. Interpolation processing is performed for each interpolation period up to the position to the cutting point command (XE, YE, ZE) at the block end point, and the cutting point interpolation position (Xt, Yt, Zt) is obtained.
(2) Interpolation from the cutting surface vertical direction command (IS, JS, KS) at the block start point to the cutting surface vertical direction command (IE, JE, KE) at the block end point, and cutting surface vertical direction interpolation for each interpolation cycle A vector (It, Jt, Kt) is obtained. The cutting surface vertical direction interpolation vector (It, Jt, Kt) is obtained as a unit vector.
(3) The tool direction vector (TSx, TSy, TSz) at the block start point and the tool direction vector (TEx, TEy, TEz) at the block end point are obtained from the tool direction commands A and C at the start point and end point in the read block. . This method is the same as the method described in (4) of the ball end mill.
(4) A tool direction interpolation vector (Ttx, Tty, Ttz) is obtained by performing interpolation processing from the tool direction vector (TSx, TSy, TSz) at the block start point to the tool direction vector (TEx, TEy, TEz) at the block end point. . This tool direction interpolation vector (Ttx, Tty, Ttz) is also obtained as a unit vector.
(5) The corner R correction vector (CCx, CCy, CCz) is obtained by multiplying the cutting surface vertical direction interpolation vector (It, Jt, Kt) by the corner R correction amount CR.
(6) The tool direction interpolation vector (Ttx, Tty, Ttz) on the plane formed by the tool direction interpolation vector (Ttx, Tty, Ttz) and the cutting surface vertical direction interpolation vector (It, Jt, Kt) is rotated by 90 degrees. (The method of rotation is the same as that of the square end mill), and the tool radius correction vector (TCx, TCx, TCx,) is multiplied by a value (TR-CR) obtained by subtracting the corner radius correction amount CR from the tool radius correction amount TR. TCy, TCz) is obtained.
(7) The tool length correction vector (TLx, TLy, TLz) is obtained by multiplying the tool direction interpolation vector (Ttx, Tty, Ttz) by a value (TL-CR) obtained by subtracting the corner R correction amount CR from the tool length correction amount TL. Ask for.
(8) At the cutting point interpolation position (Xt, Yt, Zt), a corner R correction vector (CCx, CCy, CCz), a tool radius correction vector (TCx, TCy, TCz), and a tool length correction vector (TLx, TLy, TLz) ) To obtain the linear axis control point position (Xc, Yc, Zc). This linear axis control point position (Xc, Yc, Zc) is the moving position of the linear axis (X, Y, Z axis) in the interpolation cycle.
(9) The tool direction vector (Ttx, Tty, Ttz) is converted into the rotation axis control point position (Ac, Cc). The converted rotation axis control point position (Ac, Cc) is a position where the rotation axis (A, C axis) for each interpolation period moves. This conversion method is the same as that of the ball end mill described above.

  Thus, by driving and controlling the servo motor that drives each axis so as to move to the linear axis control point position (Xc, Yc, Zc) and rotation axis control point position (Ac, Cc) obtained for each interpolation cycle. Processing is executed.

As described above, the interpolation process as described above is performed on the linear axes (X, Y, Z axes) and the rotation axes (A, C axes) when machining is performed by commanding a cutting point sequence. Machining is executed based on the movement command for each interpolation cycle. In the middle of this processing, the control may become unstable near the singular point described above, or the cut may be excessive. FIG. 9 is an explanatory diagram in the vicinity of a singular point where the control becomes unstable. In this example, the command interval distance of the cutting point command is small, and the control generated at the singular point when the movement distance of the control point is large is unstable (hereinafter, this singular point is referred to as the singular point). 1). This singular point 1 occurs under the following conditions.
(A) The direction (direction) of the tool direction vector (TSx, TSy, TSz) at the block start point and the cutting surface vertical direction command (IS, JS, KS) are close.
(B) The direction of the tool direction vector (TSx, TSy, TSz) at the block start point is close to the direction of the tool direction vector (TEx, TEy, TEz) at the block end point.
(C) The direction of the tool direction vector (TEx, TEy, TEz) at the end point of the block is close to the direction of the cutting surface vertical direction command (IE, JE, KE), and the outer product vector (Vx, Vy, Vz) on the surface formed by them. The tool direction vector (TSx, TSy, TSz) at the block start point and the outer product vector (Vx, Vy, Vz) on the surface formed by the cutting surface vertical direction command (IS, JS, KS) are greatly different. For example, it is different by about 180 °. In the example shown in FIG. 9, if each vector is on the same plane at the block start point and end point, the outer product vectors (Vx, Vy, Vz) of the block start point and end point have opposite signs and are 180 ° different. ing. As a result, a tool radius correction vector (TCx) obtained by multiplying a vector obtained by rotating (Ttx, Tty, Ttz) by 90 ° around the unit vector of the outer product vector (Vx, Vy, Vz) and the tool radius correction amount TR. , TCy, TCz) also changes greatly according to a large change in the outer product vector, for example, about 180 °. FIG. 9 shows an example in which the tool radius correction vector (TCx, TCy, TCz) is changed by about 180 °.

When the above conditions (a), (b), and (c) occur, the operation of the corresponding control point (Xc, Yc, Zc) is large even if the interval between the cutting points (command points) is small. An example as shown in FIG. 9 occurs. In the example shown in FIG. 9, the right side of the tool 1 is commanded as the cutting point at the block start point, but the left side of the tool 1 is commanded as the cutting point at the block end point. Operation about twice the diameter correction amount occurs. As described above, since the tool radius correction vector (TCx, TCy, TCz) changes greatly, the control point (Xc, Yc, Zc) fluctuates, resulting in an unstable operation.
When the control operation becomes unstable due to such a singular point, it occurs not only in the case of machining by the square end mill described above but also in the case of machining by a radius end mill.

Next, a case will be described in which the position interval of the cutting point command is large, but the movement of the control point when machining the interval is small, and the cutting amount is excessive at a singular point that moves on the loop (hereinafter referred to as this singular point). The point is called singular point 2).
FIG. 10 is an explanatory diagram of the operation at this singular point 2. FIG. The condition for generating this singularity is as follows.
(B) The position of the linear axis control point (Xc, Yc, Zc) at the block start point (hereinafter referred to as the linear axis control point (XSc, YSc, ZSc) at the block start point) and the linear axis control point at the block end point The position of (Xc, Yc, Zc) (hereinafter referred to as a linear axis control point (XEc, YEc, ZEc) at the block end point) is close.
(B) The direction of the tool direction vector (TSx, TSy, TSz) at the block start point is close to the direction of the tool direction vector (TEx, TEy, TEz) at the block end point.
(C) There is a certain distance between the position of the cutting point command (XS, YS, ZS) at the block start point and the cutting point command (XE, YE, ZE) at the block end point, and the cutting surface vertical direction command at the block start point The direction of the cutting surface vertical direction command (IE, JE, KE) at the end point of the block (IS, JS, KS) is greatly different.

  In the example shown in FIG. 10, the direction of the cutting surface vertical direction command (IS, JS, KS) (IE, JE, KE) at the block start point and the end point is greatly different, and the tool radius correction vector (TCSx, TCSy at the start point). , TCSz) and tool radius correction vectors (TCEx, TCEy, TCEz) at the end point are also greatly different. The direction of the tool direction vectors (TSx, TSy, TSz) and (TEx, TEy, TEz) at the start point and end point of the block are close, and the tool length correction vectors (TLx, TLy, TLz) at the start point and end point of the block overlap. In this state, the control point position of the linear axis obtained by adding the tool radius correction vector and the tool length correction vector to the cutting point command is a small loop-like operation. In the example shown in FIG. 10, it is expected that the linear axis control point does not operate during the command block, but actually the loop-shaped operation described by the broken-line arrow is performed. As a result, there is a problem that cutting into the workpiece occurs.

  The problem of the excessive cutting due to the singular point 2 when the command interval distance of the cutting point command is small and the control point moving distance is large is that a square end mill or a radius end mill other than the ball end mill described above is used. It also occurs when you do.

  Accordingly, an object of the present invention is to provide a control method for a 5-axis machining apparatus capable of preventing the above-described unstable operation near the singular point and cutting into a workpiece.

The invention according to claim 1 of the present invention uses a mill tool or a ball end mill that does not have a corner R portion, and sets a preset tool diameter correction amount and tool length correction amount, a cutting point commanded by a machining program, and a cutting surface. A 5-axis processing machine having three linear axes and two rotational axes for driving and controlling each axis at each control point position by obtaining a linear axis control point and a rotational axis control point for each interpolation cycle from the vertical direction and the tool direction. In the numerical control method to control, the cutting point position and linear axis control point at the block start point and end point are obtained for each block, and the distance between the linear axis control point at the block start point and end point is smaller than the first set value, and, when the distance between the cutting point positions in the block start point and the end point is determined to be larger than the second set value, or block distance between the linear axis control point at the start and end points (C When the block start point and the ratio of the values for the distance (PD) between the cutting point positions at the end (CD / PD) is determined to be smaller than the third set value of), linear axis control in the end of block The point is equal to the linear axis control point at the start point of the block, so that the linear axis movement by the command in the block is not generated, thereby generating excessive cutting near the singular point where the linear axis moves in a loop. This is a numerical control method for a 5-axis machine that prevents the above-described problem.

In the invention according to claim 2, in the invention according to claim 1, in place of the point that the movement of the linear axis is not generated in the command of the block in the vicinity of the singular point , the block start point with respect to the linear axis in the block. The movement command of the linear motion from the linear axis control point position to the linear axis control point position at the block end point .

The invention according to claim 3 uses a mill tool having a corner R portion, and sets a preset tool radius correction amount, a corner R correction amount and a tool length correction amount, a cutting point commanded by a machining program, and a cutting surface. A 5-axis processing machine having three linear axes and two rotational axes for driving and controlling each axis at each control point position by obtaining a linear axis control point and a rotational axis control point for each interpolation cycle from the vertical direction and the tool direction. In the numerical control method to control, the cutting point position and linear axis control point at the block start point and end point are obtained for each block, and the distance between the linear axis control point at the block start point and end point is smaller than the first set value, and, when the distance between the cutting point positions in the block start point and the end point is determined to be larger than the second set value, or block of the distance between the distance CD between the linear axis control point and an end point (CD) start And when the ratio of the values for the distance (PD) between the cutting point positions at the end (CD / PD) is determined to be smaller than the third set value, the linear axis control point at the block end point the block By preventing the operation of the linear axis according to the command in the block as being equal to the linear axis control point at the start point, it prevents excessive cutting near the singular point where the linear axis moves in a loop. This is a numerical control method for the five-axis machine.

In the invention according to claim 4, in the invention according to claim 3, in place of the point that the movement of the linear axis is not generated in the command of the block in the vicinity of the singular point , the block start point with respect to the linear axis in the block. The movement command of the linear motion from the linear axis control point position to the linear axis control point position at the block end point .

  In a 5-axis machine with 3 linear axes and 2 rotary axes, the position interval of the cutting point command is large, but the amount of cut that occurs at the singular point where the movement of the control point becomes small when machining the interval is prevented. can do.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 11 is a principal block diagram of a numerical control device as an embodiment of a control device that implements the present invention.

  The CPU 11 is a processor that controls the numerical controller 10 as a whole. The processor 11 drives and controls the memory 12, the display device 13, the input means 14 such as a keyboard, the interface 15, the axis control circuit 16 of each axis that controls the servo motor of each axis, and the spindle (main axis) via the bus 20. Connected to a spindle control circuit 18 or the like. The memory 12 is composed of ROM, RAM, FRAM and the like. The processor 11 reads a system program stored in the memory 12 via the bus 20 and controls the entire numerical control apparatus according to the system program. Further, the memory 12 stores machining programs such as programs constituted by cutting point commands read via the interface 15, various machining programs and various setting data inputted via the display device 13 and the input means 14, and the like. Various data are stored. In relation to the present invention, software for detecting the vicinity of the above-described singular points 1 and 2 and preventing unstable operation and excessive cutting is additionally stored in the memory 12 in comparison with the prior art. .

The axis control circuit 16 of each axis receives the movement command amount of each axis from the processor 11 and the position / speed feedback signal from the position / speed detector built in the servo motor 22 of each axis, and feeds back the position / speed. Control is performed, and commands for each axis are output to the servo amplifier 17.
In response to this command, the servo amplifier 17 drives each servo motor 22 of each axis (X axis, Y axis, Z axis, A axis, C axis) of the machine (control target). In FIG. 11, the position / speed feedback is omitted.

  Further, the spindle control circuit 18 receives a spindle rotation command from the processor 11 and a speed feedback from a position coder (not shown) that detects the rotation speed of the spindle, and performs feedback control of the speed, and sends a spindle speed signal to the spindle amplifier 19. Is output. The spindle amplifier 19 receives the spindle speed signal and rotates the spindle motor 23 at the commanded rotational speed.

  The hardware configuration of the numerical control device described above is the same as the conventional one, and the difference is software for detecting the vicinity of the singular points 1 and 2 in the memory 12 and preventing unstable operation and excessive cutting. Is newly added and stored.

First, a reference example for eliminating operation instability near the singular point 1 will be described.
FIG. 12 is an explanatory diagram of a method for detecting a singular point 1 and a method for avoiding an anxious point operation when a singular point is detected.
As described above, when the cutting surface vertical direction interpolation vector (It, Jt, Kt) is obtained and the tool direction interpolation vector (Ttx, Tty, Ttz) is obtained, the angle α formed by these two vectors is obtained. Then, it is determined whether the angle α is smaller than a value (Prm−α) set in advance. The fact that the angle α is smaller than the set value (Prm−α) means that the above-mentioned singular point 1 is generated in the state where the tip end plane of the square end mill or the radius end mill and the processing plane are almost parallel to (a) to (c). ) Is highly likely to be satisfied, and is likely to be in the vicinity of the singular point 1. Therefore, when it is detected that the angle α is smaller than the set value (Prm−α), the tool radius correction vector (TCx, TCy, TCz) is used as the tool radius correction vector of the previous interpolation cycle (one interpolation cycle before). (TCx, TCy, TCz) (Hereinafter, the tool radius correction vector before one interpolation cycle is described as (TC0x, TC0y, TC0z)), the linear axis control point position (Xc, Yc, Zc) and the rotational axis control point position (Ac, Cc) is obtained and each axis is controlled.

  As described in paragraph “0017” together with FIG. 9, when the tool radius correction vector (TCx, TCy, TCz) changes greatly, the control point (Xc, Yc, Zc) fluctuates and an unstable operation occurs. Therefore, as described here, the tool radius correction vector (TCx, TCy, TCz) is used as the tool radius correction vector (TC0x, TC0y, TC0z) in the previous interpolation cycle (one interpolation cycle before). The correction vector (TCx, TCy, TCz) is not changed. As a result, the singular point 1 is eliminated, and the unstable operation is eliminated.

Whether the angle α formed by the cutting surface vertical direction interpolation vector (It, Jt, Kt) and the tool direction interpolation vector (Ttx, Tty, Ttz) is smaller than the set value (Prm−α) is determined by the cutting surface vertical direction. An inner product of the interpolation vector (It, Jt, Kt) and the tool direction interpolation vector (Ttx, Tty, Ttz) is obtained, and the determination is made based on the inner product. That is,
cos (α) = (Ttx, Tty, Ttz) · (It, Jt, Kt)
If cos (α)> cos (Prm−α), it is determined that the angle α is smaller than the set value (Prm−α).

  Furthermore, in this reference example, once the singular point 1 is considered, after using the tool radius correction vector (TC0x, TC0y, TC0z) before one interpolation cycle, the angle α becomes larger than the set value (Prm−α). When it is determined that the singular point 1 has been eliminated, the position of the control point is obtained using the normal tool radius correction vector (TCx, TCy, TCz). At this return, the moving speed of the control point is commanded. It is possible to select one of the two speeds (speed 1) or maximum speed (speed 2).

FIG. 13 is a process flowchart for each interpolation cycle showing an algorithm centering on the detection process of the singular point 1 and the process of preventing unstable operation in the vicinity of the singular point in this reference example.
First, the processor 11 of the numerical controller reads the block command (X, Y, Z, A, C, I, J, K) from the machining program as in the conventional case, performs the interpolation process as in the conventional case,
Cutting point interpolation position (Xt, Yt, Zt)
Cutting surface vertical direction interpolation vector (It, Jt, Kt)
Tool direction interpolation vector (Ttx, Tty, Ttz)
Tool radius compensation vector (TCx, TCy, TCz)
Tool length correction vectors (TLx, TLy, TLz) are obtained.

In addition, if a radius end mill is specified,
A corner R correction vector (CCx, CCy, CCz) is also obtained (step a1).
The point for obtaining the position and vector described above for each interpolation period is the same as in the prior art.

  Next, it is determined whether or not the tool specified by the program is a ball end mill (step a2). When the ball end mill is designated, the phenomenon of the singular point 1 does not occur. Therefore, the process proceeds to step a7, and the linear axis control point position and the rotation axis control point position are obtained in the same manner as in the prior art. The obtained movement command to the position of each axis is output to each axis control circuit 16, and the servo motor 22 of each axis is driven and controlled.

  On the other hand, if the commanded tool is a square end mill or a radius end mill and not a ball end mill in step a2, the process proceeds to step a3, where the cutting surface vertical direction interpolation vector (It, Jt, Kt) and the tool direction interpolation vector are transferred. It is determined whether the inner product value of (Ttx, Tty, Ttz) is larger than the cosine value cos (Prm-α) of the value (Prm-α) set by the parameter, and the cutting surface vertical direction interpolation vector (It, Jt, It is determined whether an angle α formed by Kt) and the tool direction interpolation vector (Ttx, Tty, Ttz) is smaller than a set value (Prm−α).

  If it is determined that the angle α is not smaller than the set value (Prm−α), it is determined whether the flag FA is set to “1” (step a8). Note that the flag FA is set to “0” in the initial setting. If the flag FA is not “1”, the speed of the cutting point is set to the speed commanded by the program (step a12). When a radius end mill is specified in the register storing the tool radius correction vector (TC0x, TC0y, TC0z) before one interpolation cycle, the corner R correction vector (CC0x, CC0y before one interpolation cycle) is further specified. , CC0z), the tool radius correction vector (TCx, TCy, TCz) and the corner R correction vector (CCx, CCy, CCz) obtained in step a1 of the cycle are stored (step a6).

  Then, the linear axis control point position and the rotation axis control point position are obtained. That is, when the designated tool is a square end mill, the tool radius correction vector (TCx, TCy, TCz) and the tool length correction vector (TLx, TLy, TLz) are added to the cutting point interpolation position (Xt, Yt, Zt). Thus, the linear axis control point position (Xc, Yc, Zc) is obtained, and the rotation axis control point position (Ac, Cc) is obtained from the tool direction interpolation vector (Ttx, Tty, Ttz). On the other hand, when the designated tool is a radius end mill, a corner R correction vector (CCx, CCy, CCz), a tool radius correction vector (TCx, TCy, TCz), and a tool at the cutting point interpolation position (Xt, Yt, Zt). The length correction vector (TLx, TLy, TLz) is added to obtain the linear axis control point position (Xc, Yc, Zc), and the rotation axis control point position (Ac, Tc) is determined from the tool direction interpolation vector (Ttx, Tty, Ttz). Cc) is obtained (step a7). The movement command to the position of each axis thus obtained is output to each axis control circuit 16, and the servo motor 22 of each axis is driven and controlled.

  On the other hand, when it is determined in step a3 that the angle α formed by the cutting surface vertical direction interpolation vector (It, Jt, Kt) and the tool direction interpolation vector (Ttx, Tty, Ttz) is smaller than the set value (Prm−α). Sets the flag FA to “1” (step a4), and stores the tool radius correction vector (TC0x, TC0y, TC0z) before one interpolation cycle stored in the register as the tool radius correction vector (TCx, TCy, TCz) of the cycle. ) The corner R correction vector (CC0x, CC0y, CC0z) before one interpolation cycle is set as the corner R correction vector (CCx, CCy, CCz) of the cycle (step a5). Then, the process of step a6 described above is executed, the tool radius correction vector (TCx, TCy, TCz) and the corner R correction vector (CCx, CCy, CCz) used in the cycle are stored in a register, and in the next interpolation cycle. A tool radius correction vector (TC0x, TC0y, TC0z) and a corner R correction vector (CC0x, CC0y, CC0z) before one interpolation cycle are used.

  Next, the process of step a7 described above is executed to determine the linear axis control point position (Xc, Yc, Zc) and the rotation axis control point position (Ac, Cc). In this case, in step a5, the tool radius correction is performed. The vector (TCx, TCy, TCz) and the corner R correction vector (CCx, CCy, CCz) are the tool radius correction vector (TC0x, TC0y, TC0z) before one interpolation cycle, and the corner R correction vector (CC0x, CC0, CC0y, CC0z), the linear axis control point position (Xc, Yc, Zc) and the rotation axis control point position (Ac, Cc) are obtained using this, and unstable operation is performed. Can be prevented.

  Thus, “Yes” is determined in step a3, and the value (Prm−) in which the angle α formed by the cutting surface vertical direction interpolation vector (It, Jt, Kt) and the tool direction interpolation vector (Ttx, Tty, Ttz) is set. As long as it is determined to be smaller than α), the processing of steps a1 to a7 is executed for each interpolation cycle, and the cutting surface vertical direction interpolation vector (It, Jt, Kt) and tool direction interpolation vector (Ttx, Tty, Ttz). The linear axis control point position (Xc, Yc, Zc) and the rotation axis control point position (Ac, Cc) are obtained so that the angle α formed with the angle α is not smaller than the set value (Prm−α). Is controlled to move to this position.

  In step a3, it is determined that the angle α formed by the cutting surface vertical direction interpolation vector (It, Jt, Kt) and the tool direction interpolation vector (Ttx, Tty, Ttz) is larger than the set value (Prm−α). When the flag FA is determined to be “1” at a8 (until the previous interpolation period, it is determined that the angle α is smaller than the set value (Prm−α), and α ≧ (Prm−α) is determined in the period. ), The flag FA is set to “0” (step a9), and it is determined whether or not the setting parameter (Prm−BF) is set to “1” (step a10). This setting parameter (Prm-BF) is used to select the commanded speed or the maximum speed as the moving speed of the cutting point to be used. If it is set to "1", the commanded speed is selected. When “0” is set, the speed of the cutting point is changed to the maximum speed that does not exceed the maximum speed set by each axis parameter. The reason for changing the speed of this cutting point to the maximum speed is that it may move at a rapid speed in the interpolation cycle when it is considered not to be a singular point 1 after being considered to be near the singular point 1. It is made not to move at such an excessive speed.

In this way, the speed is changed or maintained, and the process proceeds to step a6. In the next interpolation cycle, interpolation processing is executed at the set speed in step a1, and each data is obtained. If the maximum speed is changed in step a11, the interpolation processing is performed at this maximum speed. Each data will be required.
In the next cycle, since the flag FA is set to “0” in step a9, the process proceeds from step a8 to step a12, and the speed is returned to the normal commanded speed.

  FIG. 14 is an explanatory diagram of a method for detecting the singular point 2 performed by the embodiment of the present invention and a method for avoiding an operation in which the cutting is excessive when the singular point 2 is detected. This embodiment describes an example in which the tool used is a ball end mill. In FIG. 14, the tool length correction vector (TLSx, TLSy, TLSz) at the block start point, the tool length correction vector (TLEX, TLEy, TLEz) at the block end point, and the linear axis control point (XSc) at the block start point. , YSc, ZSc) and the linear axis control point (XEc, YEc, ZEc) at the end point of the block are different vectors and positions, respectively. Expressed by position.

FIG. 15 is a flowchart of processing performed in units of blocks showing an algorithm centered on the processing for detecting the singular point 2 and the processing for preventing instability in the vicinity of the singular point in this embodiment.
In this embodiment, the distance between the position of the linear axis control point (XSc, YSc, ZSc) at the block start point and the position of the linear axis control point (XEc, YEc, ZEc) at the block end point, and the block start point Based on the distance between the position of the cutting point command (XS, YS, ZS) and the position of the cutting point command (XE, YE, ZE) at the block end point, it is determined whether or not the singular point 2 is in the vicinity. If it is in the vicinity, the movement of the linear axis control point of the block is stopped or the movement of the block is set to a linear movement, thereby preventing the occurrence of a cut or the like in response to the singular point 2. Therefore, it becomes a reference for determining whether or not the distance CD between the linear axis control point (XSc, YSc, ZSc) at the block start point and the linear axis control point (XEc, YEc, ZEc) at the block end point is small. The distance is set as a set value (Prm-C) by a parameter. Further, a reference value (Prm) for determining the singular point 2 based on the distance PD between the cutting point command (XS, YS, ZS) at the block start point and the cutting point command (XE, YE, ZE) at the block end point. -P) is set as a parameter. Whether or not the singular point is 2 is determined based on these two parameter setting values.

  As another method for determining the singular point 2, the distance CD between the linear axis control point (XSc, YSc, ZSc) at the block start point and the linear axis control point (XEc, YEc, ZEc) at the block end point and the block start point. Is determined based on the ratio of the distance PD (CD / PD) between the cutting point command (XS, YS, ZS) and the cutting point command (XE, YE, ZE) at the end point of the block. Prm-R) is set as a parameter. Then, it is possible to select which method is used to determine the singular point 2. This selection is also set by a parameter. When the setting parameter (Prm−SB) = 0, the former distances CD and PD are set. Thus, when the setting parameter (Prm−SB) = 1, the determination is made based on the latter ratio (CD / PD). Furthermore, in this embodiment, when it is regarded as the vicinity of the singular point 2, the linear axis control point position (XEc, YEc, ZEc) at the block end point is changed to the linear axis control point position (XSc, YSc, ZSc) at the block start point. The linear axis control point operation is not generated or the linear axis control point position (XSc, YSc, ZSc) at the block start point is changed to the linear axis control point position at the block end point for the linear axis. When moving to (XEc, YEc, ZEc) can be selected as a linear operation, this selection is made by parameter setting, and when the setting parameter (Prm−B4) = 0 Does not cause the operation of the linear axis control point, and when the setting parameter (Prm−B4) = 1, the linear movement is selected. In addition, about each parameter setting mentioned above, you may make it use a program command or a signal instead of parameter setting.

The command block is read, and the cutting point command (XS, YS, ZS) and the cutting surface vertical direction command (IS, JS, KS) at the start point of the block are obtained. The cutting surface vertical direction command (IS, JS, KS) at the block start point is multiplied by the tool radius correction amount TR to obtain a tool radius correction vector (TCSx, TCSy, TCSz) at the block start point. The cutting surface vertical direction command (IS, JS, KS) is assumed to be a unit vector. Further, a tool direction vector (TSx, TSy, TSz) at the block start point is obtained from the commanded block direction commands A and C at the block start point and block end point. The obtained tool direction vector (TSx, TSy, TSz) at the block start point is multiplied by (tool length correction amount TL−tool diameter correction amount TR) to obtain the tool length correction vector (TLSx, TLSy, TLSz) at the block start point. Ask. Add the tool radius correction vector (TCSx, TCSy, TCSz) at the block start point and the tool length correction vector (TLSx, TLSy, TLSz) at the block start point to the cutting point command (XS, YS, ZS) at the block start point, A linear axis control point (XSc, YSc, ZSc) at the block start point is obtained (step b1).
The processing for obtaining the linear axis control point (XSc, YSc, ZSc) at this starting point is the same as that for obtaining the linear axis control point (Xc, Yc, Zc) of the interpolation point described above, and details thereof are omitted.

Next, a cutting point command (XE, YE, ZE) and a cutting surface vertical direction command (IE, JE, KE) at the end point of the block are obtained. The cutting surface vertical direction command (IE, JE, KE) at the block end point is multiplied by the tool diameter correction amount TR to obtain a tool diameter correction vector (TCEx, TCEy, TCEz) at the block end point. The cutting surface vertical direction command (IE, JE, KE) is assumed to be a unit vector. A tool direction vector (TEx, TEy, TEz) at the block end point is obtained from the commanded direction A and C at the block start point and block end point. The tool direction vector (TEx, TEy, TEz) at the block end point is multiplied by (tool length correction amount TL−tool diameter correction amount TR) to obtain a tool length correction vector (TLEX, TLEy, TLEz) at the block end point. .
Add the tool radius correction vector (TCEx, TCEy, TCEz) at the block end point and the tool length correction vector (TLEX, TLEy, TLEz) at the block end point to the cutting point command (XE, YE, ZE) at the block end point, A linear axis control point (XEc, YEc, ZEc) at the block end point is obtained (step b2).

The processing for obtaining the linear axis control point (XEc, YEc, ZEc) at this end point is the same method as that for obtaining the linear axis control point (Xc, Yc, Zc) of the interpolation point described above, and the details are omitted. To do. Further, since the end point of the block is the start point of the next block, each data obtained at the end point of the block can be used as the data of the start point of the next block. Each data of the block end point obtained in step b2 of the previous cycle may be replaced with the start point data of the block.

  Next, the distance CD between the linear axis control point (XSc, YSc, ZSc) at the block start point and the linear axis control point (XEc, YEc, ZEc) at the block end point, and the cutting point command (XS, XS, at the block start point) YS, ZS) and the distance PD between the cutting point commands (XE, YE, ZE) at the block end point are obtained (step b3).

Then, it is determined whether or not the value of the setting parameter (Prm-SB) is “0” (step b4). If it is “0”, it is determined whether or not the singularity is 2 based on the distances CD and PD. It is determined whether the distance CD between the block start point and the end point linear axis control point is smaller than the set value (Prm-C) (step b5). When the distance CD is equal to or greater than the set value (Prm-C), the process is terminated. If the distance CD is smaller than the set value (Prm-C), it is determined whether the distance PD between the cutting point commands at the block start point and end point is greater than the set value (Prm-P) (step b6).
When the distance PD is less than or equal to the set value (Prm−P), the process ends. On the other hand, when the distance PD is larger than the set value (Prm−P), it is determined that it is near the singular point 2 and the process proceeds to step b7. That is, when the distance CD between the linear axis control points at the block start point and the end point is small and the distance PD between the cutting point commands at the block start point and the end point is large, the processing by the block command is processing near the singular point 2. Judge that there is.

  When the value of the setting parameter (Prm−SB) is set to “1”, it is determined whether the ratio of the distance CD to PD (CD / PD) is smaller than the setting value (Prm−R), and is not small. In some cases, it is determined that it is not in the vicinity of the singular point 2 and the process is terminated. On the other hand, when the ratio of the distance CD to PD (CD / PD) is smaller than the set value (Prm-R), it is determined that the processing by the block is processing near the singular point 2, and the process proceeds to step b7.

  When it is determined that the singular point 2 is in the vicinity in this way, it is determined in step b7 whether or not the setting parameter (Prm−B4) is set to “1”, and the setting parameter (Prm−B4) = 0. Is set so that the linear axis control point position (XEc, YEc, ZEc) at the end point of the block becomes the linear axis control point position (XSc, YSc, ZSc) at the block start point (step b8). As a result, when the interpolation processing for the block is executed, a movement command for the linear axes to the XYZ axes is not generated. On the other hand, when the setting parameter (Prm−B4) is set to “1”, the linear axis control point position (XSc, YSc, ZSc) at the block start point relative to the linear axis in the block is changed to the block end point. A linear operation is commanded as a movement command to the linear axis control point position (XEc, YEc, ZEc) (step b9). This prevents a loop-like unstable operation from occurring and prevents excessive cutting into the workpiece.

In the above-described embodiment of the present invention, the example in which the ball end mill is used as the tool has been described. However, the phenomenon of the singular point 2 occurs even when the tool used is a square end mill or a radius end mill. Similarly, in the case of square end mills and radius end mills, by detecting the vicinity of singular point 2 and performing the same processing, the occurrence of unstable loop-like motion is prevented and excessive cutting into the workpiece is prevented. To do.
When the tool used is not a ball end mill but a square end mill or a radius end mill, only the data obtained in steps b1 and b2 in FIG. 15 are different, and the processing after step b3 is the same.

For square end mills,
Find the next data at the starting point.
Cutting point command (XS, YS, ZS)
Cutting surface vertical direction command (IS, JS, KS)
Tool radius compensation vector (TCSx, TCSy, TCSz)
Tool direction vector (TSx, TSy, TSz)
Tool length compensation vector (TLSx, TLSy, TLSz)
Linear axis control point (XSc, YSc, ZSc)
(XSc, YSc, ZSc) = (XS, YS, ZS) + (TCSx, TCSy, TCSz) + (TLSx, TLSy, TLSz)
Also, the next data at the end point is obtained.
Cutting point command (XE, YE, ZE)
Cutting surface vertical direction command (IE, JE, KE)
Tool radius compensation vector (TCEx, TCEy, TCEz)
Tool direction vector (TEx, TEy, TEz)
Tool length compensation vector (TLEX, TLEy, TLEz)
Linear axis control point (XEc, YEc, ZEc)
(XEc, YEc, ZEc) = (XE, YE, ZE) + (TCEx, TCEy, TCEz) + (TLEX, TLEy, TLEz)
Note that the tool radius correction vector, tool direction vector, and tool length correction vector at the interpolation point described with reference to FIG. This is equivalent to a method for obtaining a vector, and the description is omitted.

For radius end mills,
Find the next data at the starting point.
Cutting point command (XS, YS, ZS)
Cutting surface vertical direction command (IS, JS, KS)
Corner R correction vector (CCSx, CCSy, CCSz)
Tool radius compensation vector (TCSx, TCSy, TCSz)
Tool direction vector (TSx, TSy, TSz)
Tool length compensation vector (TLSx, TLSy, TLSz)
Linear axis control point (XSc, YSc, ZSc)
(XSc, YSc, ZSc) = (XS, YS, ZS) + (CCSx, CCSy, CCSz) + (TCSx, TCSy, TCSz) + (TLSx, TLSy, TLSz)
Also, the next data at the end point is obtained.
Cutting point command (XE, YE, ZE)
Cutting surface vertical direction command (IE, JE, KE)
Corner R correction vector (CCEx, CCEy, CCEz)
Tool radius compensation vector (TCEx, TCEy, TCEz)
Tool direction vector (TEx, TEy, TEz)
Tool length compensation vector (TLEX, TLEy, TLEz)
Linear axis control point (XEc, YEc, ZEc)
(XEc, YEc, ZEc) = (XE, YE, ZE) + (CCEx, CCEy, CCEz) + (TCEx, TCEy, TCEz) + (TLEX, TLEy, TLEz) Corner R correction at the block start and end points The method for obtaining the vector, the tool radius compensation vector, the tool direction vector, and the tool length compensation vector is the same as the method for obtaining the tool radius compensation vector, the tool orientation vector, and the tool length compensation vector at the interpolation point described in FIG. Yes, the description is omitted.

It is explanatory drawing of the relationship between the commanded cutting point and the tool position controlled when using a ball end mill as a tool in a 5-axis processing machine. It is explanatory drawing explaining the relationship between the cutting point and control point by a general cutting point command in the example of a square end mill. When a ball end mill is used as a tool, it is an operation explanatory diagram when the positions of the X, Y and Z axis linear axes and the A and C axis rotation axes are determined and controlled from a cutting point command. It is a figure which shows the example of a program by the cutting point command which designated the ball end mill as a tool. It is a figure which shows the example of a setting of a tool correction amount. When the tool used is a square end mill, it is an operation explanatory diagram when the positions of the X, Y and Z axis linear axes and the A and C axis rotation axes are determined and controlled from the cutting point command. When the tool used is a radius end mill, it is an operation explanatory diagram when the positions of the three X, Y, and Z linear axes and the rotation axes of the A and C axes are determined and controlled from a cutting point command. It is a figure which shows the example of a program by the cutting point command which designated the radius end mill as a tool to be used. It is explanatory drawing of the singular point vicinity where operation | movement becomes unstable. It is explanatory drawing of the singularity vicinity which an excessive cutting | disconnection produces. It is a principal part block diagram of the numerical control apparatus as a control apparatus which implements this invention. It is explanatory drawing of the detection method of the singular point in the reference example of this invention, and the method of avoiding an anxious point operation | movement when a singular point is detected. It is a process flowchart for every interpolation period which shows the algorithm centering on the detection process of the singular point in the same reference example, and the process which prevents operation | movement instability in the vicinity of this singular point. It is explanatory drawing of the detection method of the singular point in embodiment of this invention, and the method of avoiding the anxious point operation | movement when a singular point is detected. 5 is a process flowchart executed in units of blocks showing an algorithm centering on a process for detecting a singular point and a process for preventing unstable operation in the vicinity of the singular point in the embodiment of the present invention.

Explanation of symbols

(X, Y, Z) Cutting point command (XS, YS, ZS) Cutting point command at block start point (XE, YE, ZE) Cutting point command at block end point (Xt, Yt, Zt) Cutting point interpolation position (I, J, K) Cutting surface vertical direction command (IS, JS, KS) Cutting surface vertical direction command at block start point (IE, JE, KE) Cutting surface vertical direction command at block end point (It, Jt, Kt) Cutting surface Vertical direction interpolation vector (Tx, Ty, Tz) Tool direction vector (TSx, TSy, TSz) Tool direction vector at block start point (TEx, TEy, TEz) Tool direction vector at block end point (Ttx, Tty, Ttz) Tool Direction interpolation vector (Xc, Yc, Zc) Linear axis control point Ac, Cc Rotary axis control point position (TCx, TCy, TCz) Tool radius compensation vector (TLx, Tc) y, TLZ) tool length compensation vector (CCx, CCy, CCz) corner R compensation vector

Claims (4)

Using a mill tool or ball end mill that does not have a corner R section, the interpolation cycle is calculated from the preset tool radius compensation amount and tool length compensation amount, and the cutting point, cutting surface vertical direction, and tool direction specified by the machining program. In a numerical control method for controlling a 5-axis processing machine having three linear axes and two rotary axes for obtaining a linear axis control point and a rotary axis control point for each control point position, and driving and controlling each axis at each control point position.
For each block, find the cutting point position and linear axis control point at the block start point and end point,
It was determined that the distance between the linear axis control points at the block start point and the end point is smaller than the first set value, and the distance between the cutting point positions at the block start point and end point is greater than the second set value. Or a ratio value (CD / PD) of the distance (CD) between the linear axis control points at the block start point and the end point to the distance (PD) between the block start point and the cutting point position at the end point is a third value. When it is determined that the value is smaller than the set value , the linear axis control point at the end point of the block is assumed to be equal to the linear axis control point at the start point of the block so that the operation of the linear axis by the command in the block is not generated. A numerical control method for a 5-axis machining apparatus. Using a mill tool or ball end mill that does not have a corner R section, the interpolation cycle is calculated from the preset tool radius compensation amount and tool length compensation amount, and the cutting point, cutting surface vertical direction, and tool direction specified by the machining program. In a numerical control method for controlling a 5-axis processing machine having three linear axes and two rotary axes for obtaining a linear axis control point and a rotary axis control point for each control point position, and driving and controlling each axis at each control point position.
For each block, find the cutting point position and linear axis control point at the block start point and end point,
It was determined that the distance between the linear axis control points at the block start point and the end point is smaller than the first set value, and the distance between the cutting point positions at the block start point and end point is greater than the second set value. Or a ratio value (CD / PD) of the distance (CD) between the linear axis control points at the block start point and the end point to the distance (PD) between the block start point and the cutting point position at the end point is a third value. When it is determined that the value is smaller than the set value, a linear motion movement command from the linear axis control point position at the block start point to the linear axis control point position at the block end point with respect to the linear axis in the block is used. A numerical control method for a 5-axis machine. Using a mill tool having a corner R section, interpolation is performed from the preset tool radius compensation amount, corner radius compensation amount and tool length compensation amount, and the cutting point, cutting surface vertical direction and tool direction specified by the machining program. In a numerical control method for controlling a 5-axis processing machine having three linear axes and two rotary axes for determining and driving a linear axis control point and a rotary axis control point for each cycle, and controlling each axis at each control point position,
For each block, find the cutting point position and linear axis control point at the block start point and end point,
It was determined that the distance between the linear axis control points at the block start point and the end point is smaller than the first set value, and the distance between the cutting point positions at the block start point and end point is greater than the second set value. Or a ratio value (CD / PD) of the distance (CD) between the linear axis control points at the block start point and the end point to the distance (PD) between the block start point and the cutting point position at the end point is a third value. When it is determined that the value is smaller than the set value , the linear axis control point at the end point of the block is assumed to be equal to the linear axis control point at the start point of the block so that the operation of the linear axis by the command in the block is not generated. A numerical control method for a 5-axis machining apparatus. Using a mill tool having a corner R section, interpolation is performed from the preset tool radius compensation amount, corner radius compensation amount and tool length compensation amount, and the cutting point, cutting surface vertical direction and tool direction specified by the machining program. In a numerical control method for controlling a 5-axis processing machine having three linear axes and two rotary axes for determining and driving a linear axis control point and a rotary axis control point for each cycle, and controlling each axis at each control point position,
For each block, find the cutting point position and linear axis control point at the block start point and end point,
It was determined that the distance between the linear axis control points at the block start point and the end point is smaller than the first set value, and the distance between the cutting point positions at the block start point and end point is greater than the second set value. Or a ratio value (CD / PD) of the distance (CD) between the linear axis control points at the block start point and the end point to the distance (PD) between the block start point and the cutting point position at the end point is a third value. When it is determined that the value is smaller than the set value, a linear motion movement command from the linear axis control point position at the block start point to the linear axis control point position at the block end point with respect to the linear axis in the block is used. A numerical control method for a 5-axis machine.

Images