JP5426153B2 - Numerical control device for a machine tool having a rotating shaft - Google Patents

Description

  The present invention relates to a numerical control device for a machine tool having a rotating shaft.

  Using a five-axis machine with three linear axes and two rotation axes, machining of complicated and difficult shapes that could not be done by three-axis machining is performed.

  In Patent Literature 1, the interpolation point of the movement path is corrected while interpolating each of the movement command of the tool tip point and the tool direction (tool posture) based on the relative movement speed of the workpiece and the tool. A technique for driving the servo motor so that the tool tip point moves on the commanded movement path at the commanded speed is disclosed. The technique disclosed in this document does not include a technique for smoothly changing the tool posture.

  In Patent Literature 2, a machining point moves on a smooth curve generated from a command point sequence from a commanded point sequence and vector sequence, and a vector tip point moves on a smooth curve generated from a command vector sequence. Interpolating means for interpolating the machining point and the vector tip point so as to change, from the interpolated machining point, the interpolated vector tip point, the set tool radius compensation amount and the set tool length compensation amount A technique for generating a position of a linear movement axis and a rotation axis and moving the axis is disclosed.

  In Patent Document 3, in a method of generating a smooth curve from a command point sequence and interpolating along the curve, the linear axis 3 is divided into elements for three linear axes and elements for two or more rotational axes. A technique is disclosed in which a smooth curve is generated for an element of an axis, a smooth curve is generated for an element of two or more rotation axes, and the rotation axis is smoothly changed by interpolating them. Yes.

Japanese Patent Laid-Open No. 2003-195917 JP 2005-182437 A JP 2006-309645 A

  In machining with a 5-axis machine, based on the movement command of the tool tip point and the tool direction (tool posture) as in Patent Document 1, based on the relative movement speed of the commanded workpiece and the tool. The tool direction (tool posture) is also interpolated while interpolating the movement path of the tool tip point, and the tool tip point moves along the commanded movement path at the commanded speed while the tool direction (tool posture) changes. Is becoming common. Such commands and machining methods are called tool tip point control. Normally, this program command is created by the CAM.

  Here, there is a case where a workpiece side surface that is a smooth curved surface is processed while performing tool tip point control, and in this case, it is necessary to perform processing while the tool posture (tool direction) is smoothly changed. One technique for this is disclosed in Patent Document 2, and the other is disclosed in Patent Document 3.

  However, in the technique of Patent Document 2, control is performed so that the machining point moves on a smooth curve and the tool posture (tool direction) changes smoothly. Since the smoothness of the movement of the machining point and the smoothness of the change in the tool posture (tool direction) are controlled separately, there is no guarantee that the machining surface itself will be smooth.

  Moreover, in the technique of patent document 3, it controls so that a processing point (three linear axes) moves on a smooth curve, and a rotating shaft changes smoothly. This technique is similar to the present invention described later in that it smoothly processes including the rotating shaft, but the reference tool length position is obtained so that the position of the reference tool length as in the present invention changes smoothly. Therefore, a technique for smoothly changing the tool posture is not disclosed. Even in this technique, since the smoothness of the movement of the machining point and the smoothness of the movement of the rotary shaft are controlled separately, there is no guarantee that the machining surface itself will be smooth.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a numerical control device that controls a machine tool having a rotating shaft so that a machining point moves on a smooth curve and a reference tool length position changes smoothly.

The invention according to claim 1 of the present application is for controlling a machine tool having at least one of a plurality of linear movement axes and a rotational movement axis to continuously process a workpiece fixed on a table with a tool. In the numerical control device, the correction amount command means for commanding or setting the actual tool length correction amount and the reference tool length correction amount, the block continuously commanded on the machining program is read, and the machining point command string and the tool attitude command string are obtained. A command sequence creating means for creating, a machining point curve generating means for creating a smooth machining point curve from the machining point command sequence, a tool posture unit vector sequence from the tool posture command sequence, and the tool posture unit vector sequence the calculated reference tool length vector sequence by integrating the reference tool length compensation amount, to generate a reference tool length position row by adding the reference tool length vector sequence in the machining point command column A quasi-tool length position sequence generating means, a reference tool length position curve generating means for generating a smooth reference tool length position curve from the reference tool length position sequence, and the machining point curve and the reference tool length position curve at regular intervals. Interpolation position calculation means for interpolating and obtaining an interpolation machining position and an interpolation reference tool length position in each interpolation cycle, and interpolation for obtaining an interpolation tool posture from the interpolation machining position and the interpolation reference tool length position obtained by the interpolation position calculation means Tool position calculation means, axis position generation means for generating the axis position of the linear movement axis and the axis position of the rotation movement axis from the interpolation tool attitude, the interpolation machining position, and the actual tool length correction amount, and the generated A numerical control device for a machine tool having a rotating shaft, comprising: an axis moving means for moving to an axis position.

According to a second aspect of the present invention, the machining point curve generating means generates a machining point approximate curve based on the machining point command sequence, and the machining point command sequence is positioned closest to the machining point approximate curve. A correction machining point sequence corresponding to the machining point command sequence is obtained by moving within a first set tolerance amount, and the machining point curve is obtained as a curve passing through the correction machining point sequence. 1 is a numerical control device for a machine tool having the rotating shaft according to 1;
The invention according to claim 3 is characterized in that the machining point curve generation means obtains the machining point curve as a curve passing through the machining point command sequence based on the machining point command sequence. A numerical control device for a machine tool having a rotating shaft.
In the invention according to claim 4, the reference tool length position curve generating means generates a reference tool length position approximate curve based on the reference tool length position sequence, and the reference tool length position sequence is approximated to the reference tool length position sequence. A correction reference tool length position sequence corresponding to the reference tool length position sequence is obtained by moving within the second set tolerance amount toward the closest position on the curve, and as a curve passing through the correction reference tool length position sequence The numerical control device for a machine tool having a rotating shaft according to claim 1, wherein the reference tool length position curve is obtained.

The invention according to claim 5 is characterized in that the reference tool length position curve generating means obtains the reference tool length position curve as a curve passing through the reference tool length position sequence based on the reference tool length position sequence. A numerical control device for a machine tool having the rotating shaft according to claim 1.
According to a sixth aspect of the present invention, the tool posture command sequence is commanded by the position of the two rotational movement shafts. The machine tool for a machine tool having the rotational shaft according to any one of the first to fifth aspects. It is a numerical control device.
The invention according to claim 7 is a numerical control device for a machine tool having a rotating shaft according to any one of claims 1 to 5, wherein the tool posture command sequence is commanded as a tool posture vector. is there.
According to an eighth aspect of the present invention, the correction amount command means also commands or sets an actual tool radius correction amount and a tool radius correction direction, and the command sequence creating means includes a preceding / following block command, a subsequent block command, Machining by obtaining a tool radius correction vector at the end point of the previous block from the tool radius correction amount and the tool radius correction direction, and using the position obtained by adding the tool radius correction vector to the linear movement axis end point position of the previous block as a machining point A numerical control device for a machine tool having a rotating shaft according to any one of claims 1 to 7, wherein a point command sequence is created.

  In the invention according to claim 9, the correction amount commanding unit also commands or sets an actual tool radius correction amount and a tool radius correction direction, and the machining point curve generation unit linearly represents a function representing the machining point curve. A differentiated machining point derivative is also generated, and the reference tool length position curve generation means also generates a reference tool length position derivative obtained by first-order differentiation of the function representing the reference tool length position curve, and calculates the interpolation position. The means calculates a machining point tangent vector and a reference tool length position tangent vector by interpolating the machining point derivative and the reference tool length position derivative, and the interpolation tool posture calculation means includes the interpolation tool posture, The radius correction is performed by calculating a radius correction interpolation machining position and a radius correction interpolation reference tool length position from the machining point tangent vector, the reference tool length position tangent vector, the actual tool radius correction amount and the tool radius correction direction. The interpolated machining position is substituted into the interpolation machining position, the radius correction interpolation reference tool length position is substituted into the interpolation reference tool length position, and a tool posture is obtained again from the interpolation machining position and the interpolation reference tool length position. The numerical control device for a machine tool having a rotating shaft according to any one of claims 1 to 7, wherein the numerical control device is substituted for a posture.

  In the invention according to claim 10, the correction amount command means also commands or sets an actual tool radius correction amount and a tool radius correction direction, and the interpolation position calculation means includes the interpolation machining position and the interpolation reference tool length position. A machining point tangent vector and a reference tool length position tangent vector are calculated from the interpolation machining position in the past interpolation cycle and the interpolation reference tool length position in the past interpolation cycle, and the interpolation tool posture calculation means is configured to calculate the interpolation tool posture. The diameter correction interpolation machining position and the diameter correction interpolation reference tool length position are calculated from the machining point tangent vector, the reference tool length position tangent vector, the actual tool radius correction amount and the tool radius correction direction, and the radius correction interpolation machining position is calculated. Is substituted into the interpolation machining position, the radius correction interpolation reference tool length position is substituted into the interpolation reference tool length position, the interpolation machining position and the interpolation reference A numerical controller for a machine tool having an axis of rotation according to any one of claims 1 to 7, characterized in that assigned to the interpolation tool attitude sought again tool attitude from ingredients length position.

  According to the present invention, it is possible to provide a numerical control device that controls a machine tool having a rotating shaft so that a machining point moves on a smooth curve and a reference tool length position changes smoothly.

  According to the present invention, in a numerical control apparatus for controlling a 5-axis machining machine that processes a workpiece mounted on a table by three linear axes and two rotary axes, the command machining point is interpolated with a smooth curve. , Interpolate the reference tool length position with a smooth curve, calculate the tool posture from the interpolated machining position and the interpolated reference tool length position, and control the linear axis and the rotation axis to be the calculated tool posture By doing so, it is possible to provide a numerical control device that can perform machining while the tool posture changes smoothly. Thus, a machining surface surrounded by a smooth curve in which the machining point moves and a curve in which the reference tool length position changes smoothly is always obtained as a smooth curved surface.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic functional block diagram of a numerical control apparatus according to the present invention.
The numerical controller 100 reads the command program by the program reading means 1, analyzes each block in the read program by block analysis 2, performs interpolation 3 based on the analyzed data, and sets each axis based on the interpolated axis position data. Operate servo 4.

  The correction amount command unit 5 is added as a part of the program reading unit 1. Here, it is added as a part of the program reading means 1, but it can also be set as a parameter separately. The machining point curve generation means 6, the reference tool length position sequence generation means 7, and the reference tool length position curve generation means 8 are added as part of the block analysis. The interpolation position calculation means 9, the interpolation tool posture calculation means 10, and the axis position generation means 11 are added as part of the interpolation 3.

  Next, using Embodiments 1 to 5, the command machining point is interpolated with a smooth curve and the reference tool length position is interpolated with a smooth curve, and the interpolated machining position and the interpolated reference tool length position are interpolated. The numerical control device 100 realizes machining while smoothly changing the tool posture by calculating the tool posture from the above and controlling the linear axis and the rotation axis of the 5-axis machine so as to obtain the calculated tool posture. Will be explained.

  Hereinafter, an embodiment of the present invention will be described by taking a tool head rotary machine as shown in FIG. 2 as an example of a 5-axis processing machine. However, for a table rotating machine in which the table is rotated and tilted by two rotating shafts, or a mixed type machine in which the table is rotated by one rotating shaft and the tool head is tilted by the other rotating shaft. The present invention can also be applied. In addition, since a table rotary type machine and a mixing type machine are publicly known, illustration is omitted.

Embodiment 1
This is explained in the following program command sequence.
<Program command>
G aa H hh Q qq;
X Px1 Y Py1 Z Pz1 B Pb1 C Pc1;
X Px2 Y Py2 Z Pz2 B Pb2 C Pc2;
...
X Pxn-2 Y Pyn-2 Z Pzn-2 B Pbn-2 C Pcn-2;
X Pxn-1 Y Pyn-1 Z Pzn-1 B Pbn-1 C Pcn-1;
X Pxn Y Pyn Z Pzn B Pbn C Pcn;
X Pxn + 1 Y Pyn + 1 Z Pzn + 1 B Pbn + 1 C Pcn + 1;
X Pxn + 2 Y Pyn + 2 Z Pzn + 2 B Pbn + 2 C Pcn + 2;
...
...
G bb;
Here, Gaa is a G code for making a mode for smoothly controlling the tool posture according to the present invention, and Gbb is a G code for releasing the mode. Hhh is a correction number for instructing an actual tool length correction amount, whereby the actual tool length is instructed. Qqq is a correction number code for instructing a reference tool length correction amount, whereby the reference tool length is instructed. Here, the actual tool length and the reference tool length are commanded by a program, but it is also possible to set them in parameters or the like.

  The command values for the linear axis X-axis, Y-axis, and Z-axis are machining point command strings (Pi (Pxi, Pyi, Pzi), i = 1, 2,... N-2, n-1, n, n +. 1, n + 2 ...). The command values for the rotational movement axes B-axis and C-axis are tool posture command strings (Vi (Pci, Pbi), i = 1, 2,... N-2, n-1, n, n + 1, n + 2. ..). Here, the rotational movement axes are the B axis and the C axis, but a combination of the A axis and the C axis, and a combination of the A axis and the B axis are also possible.

The numerical controller 100 reads the continuous block of the program command of the first embodiment by the program reading means 1, and by the block analysis 2, the machining point command sequence (Pi (Pxi, Pyi, Pzi), i = 1, 2,. n-2, n-1, n, n + 1, n + 2,...) and tool orientation command sequence (Vi (Pci, Pbi), i = 1, 2,... n-2, n-1 , N, n + 1, n + 2,.
Here, the actual tool length correction amount and the reference tool length correction amount are commanded or set by the correction amount command means 5.

  Next, generation of a smooth machining point curve by the machining point curve generating means 6 from the machining point command sequence shown in FIG. 3 will be described. First, an approximate curve is created by the least square method for the machining point command sequence. It is a well-known technique to use the least squares method for creating an approximate curve.

  Next, a modified machining point sequence corresponding to the machining point command sequence is obtained by moving the machining point command sequence toward the closest position on the machining point approximate curve within the first set tolerance amount. If the modified machining point is on the approximate curve, use the first derivative of the approximate curve at the modified machining point.If the modified machining point is not on the approximate curve, use the approximate curve at the closest position on the approximate curve. The primary differential value is used to obtain the primary differential value at each correction processing point (see FIG. 4). However, FIG. 4 shows the former, that is, the case where the corrected machining point is on the approximate curve, and the latter, that is, the case where the corrected machining point is not on the approximate curve is not particularly illustrated.

A cubic polynomial curve can be generated based on the position of each corrected machining point thus obtained and the corresponding primary differential value. More specifically, the machining point command sequence is P ₁ , P ₂ ,. . . P _n , P _{n + 1,.} . . , And the corresponding modified machining point sequences are Q ₁ , Q ₂ ,. . . Q _n , Q _{n + 1} ,. . . And the first derivative values of the modified machining point sequence are Q ₁ ^' , Q ₂ ^' ,. . . Q _n ^' , Q _{n + 1} ^' ,. . . Suppose that Then, Equation 1 which is a cubic polynomial curve using the parameter t between the modified machining points Q _n and Q _{n + 1} as a parameter is represented by Q _n , Q _{n + 1} , Q _n ^′ and Q _{n + 1} ^′. Can be obtained by calculating the respective coefficients A, B, C, and D.

Here, P _{n (t)} , A _n , B _n , and C _n are vectors having x, y, and z elements (see FIG. 5). Similarly, a cubic polynomial curve between each corrected machining point can be obtained. The machining point curve shown in FIG. 6 can be obtained by combining the cubic polynomial curves between these corrected machining points.

  An approximate curve is created by the least square method for the machining point command sequence, and the machining point command sequence is moved within the first set tolerance amount toward the closest position on the machining point approximate curve. Although the corrected machining point sequence corresponding to the command sequence is obtained, if the first set tolerance is set to 0 (zero), the machining point curve can be obtained as a curve passing through all the machining point command sequences.

  In the above description, a cubic polynomial curve is used. However, a machining point curve can be obtained using a NURBS curve, a spline curve, a Bezier curve, or the like.

Next, generation of a reference tool length position sequence by the reference tool length position sequence generation means 7 will be described.
First, a tool is expressed by Formula 2 from a tool attitude command sequence (Vi (Pci, Pbi), i = 1, 2,... N-2, n-1, n, n + 1, n + 2,...). Posture unit vector sequences (Ui (Ii, Ji, Ki), i = 1, 2,... N-2, n-1, n, n + 1, n + 2,...) Are calculated. The symbol “*” means integration.

  By adding the reference tool length Ls commanded by the program command Qqq to this, a reference tool length vector sequence is obtained and added to the machining point command sequence Pi (Pxi, Pyi, Pzi), thereby obtaining a reference tool length position sequence Si (Sxi). , Syi, Szi) is generated by the equation (3).

Next, generation of a reference tool length position curve by the reference tool length position curve generation means 8 will be described.
A smooth reference tool length position curve is generated for the reference tool length position sequence in the same manner as the processing point curve is obtained for the above-described processing point command sequence (see FIG. 7). That is, a reference tool length position approximate curve is generated based on the reference tool length position sequence, and the reference tool length position sequence is moved within the second set tolerance amount toward the closest position on the reference tool length position approximate curve. Thus, a corrected reference tool length position sequence corresponding to the reference tool length position sequence is obtained, and a reference tool length position curve is obtained as a curve passing through the corrected reference tool length position sequence. When the machining point curve is obtained for the machining point command sequence, the first set tolerance amount is used, but here, the second set tolerance amount is used. Similarly, if the second set tolerance amount is set to 0 (zero), the reference tool length position curve can be obtained as a curve passing through the reference tool length command sequence.

Next, it will be described how the interpolation position calculation means 9 determines the interpolation machining position Cp (Cpx, Cpy, Cpz) and the interpolation reference tool length position Sp (Spx, Spy, Spz).
The obtained machining point curve and the reference tool length position curve are interpolated at fixed intervals, and an interpolation machining position Cp (Cpx, Cpy, Cpz) and an interpolation reference tool length position Sp (Spx, Spy, Spz) in each interpolation cycle are obtained. .
Next, calculation of the interpolation tool posture Tp (Tpx, Tpy, Tpz) by the interpolation tool posture calculation means 10 will be described. An interpolation tool posture Tp (Tpx, Tpy, Tpz) is obtained from the interpolation machining position Cp and the interpolation reference tool length position Sp by Equation (4).

Next, the generation of the position (x, y, z) of the linear movement axis and the position (B, C) of the rotational movement axis by the axis position generation means 11 will be described.
From the interpolation machining position Cp, the interpolation tool posture Tp, and the actual tool length La commanded by the program command Hhh, the position (x, y, z) of the linear movement axis and the position (B, C). B and C generally have a plurality of solutions, but here, a solution close to the command values Pbi and Pci of B and C in the block command of the block being interpolated is selected.

The tool is moved to the axis position thus generated as shown in FIG.
According to the present embodiment, in a numerical control device that controls a 5-axis processing machine that processes a workpiece mounted on a table with three linear axes and two rotation axes, the command machining point is interpolated with a smooth curve. At the same time, the reference tool length position is interpolated with a smooth curve, the tool posture is calculated from the interpolated machining position and the interpolated reference tool length position, and the linear axis and rotary axis are set so as to obtain the calculated tool posture. It is possible to provide a numerical control device that can perform machining while smoothly changing the tool posture.

● Embodiment 2
This is explained in the following program command sequence.
<Program command>
G aa H hh Q qq;
X Px1 Y Py1 Z Pz1 I Pi1 J Pj1 K Pk1;
X Px2 Y Py2 Z Pz2 I Pi2 J Pj2 K Pk2;
...
X Pxn-2 Y Pyn-2 Z Pzn-2 I Pin-2 J Pjn-2 K Pkn-2;
X Pxn-1 Y Pyn-1 Z Pzn-1 I Pin-1 J Pjn-1 K Pkn-1;
X Pxn Y Pyn Z Pzn I Pin J Pjn K Pkn;
X Pxn + 1 Y Pyn + 1 Z Pzn + 1 I Pin + 1 J Pjn + 1 K Pkn + 1;
X Pxn + 2 Y Pyn + 2 Z Pzn + 2 I Pin + 2 J Pjn + 2 K Pkn + 2;
...
...
G bb;
The G, H, Q, X, Y, and Z commands are the same as those in the first embodiment. The I, J, and K commands are tool posture command strings (Vm (Pim, Pjm, Pkm), m = 1, 2,... N−2, n−1, n, n + 1, n + 2,...). The tool posture (tool direction) is commanded. Here, Vm is a unit vector. A processing point curve is obtained in the same manner as in the first embodiment. In the second embodiment, the tool posture unit vector string in the first embodiment is obtained as a formula 6 instead of the formula 2.

Further, the reference tool length position curve is obtained in the same manner as in the first embodiment. Next, the machining point curve and the reference tool length position curve are interpolated at fixed intervals, and an interpolation machining position Cp (Cpx, Cpy, Cpz) and an interpolation reference tool length position Sp (Spx, Spy, Spz) in each interpolation cycle are obtained. . Next, an interpolation tool posture Tp (Tpx, Tpy, Tpz) is obtained from the interpolation machining position Cp and the interpolation reference tool length position Sp.
Then, the position (X, Y, Z) of the linear movement axis and the position (B, C) of the rotational movement axis are calculated from the interpolation tool posture Tp, the interpolation machining position Cp, and the actual tool length La specified by the program command Hhh. Generate and move to the generated axis position.

Embodiment 3
This is explained in the following program command sequence.
<Program command>
G aa G cc H hh Q qq D dd;
X Px1 Y Py1 Z Pz1 B Pb1 C Pc1;
X Px2 Y Py2 Z Pz2 B Pb2 C Pc2;
. . .
X Pxn-2 Y Pyn-2 Z Pzn-2 B Pbn-2 C Pcn-2;
X Pxn-1 Y Pyn-1 Z Pzn-1 B Pbn-1 C Pcn-1;
X Pxn Y Pyn Z Pzn B Pbn C Pcn;
X Pxn + 1 Y Pyn + 1 Z Pzn + 1 B Pbn + 1 C Pcn + 1;
X Pxn + 2 Y Pyn + 2 Z Pzn + 2 B Pbn + 2 C Pcn + 2;
. . .
. . .
G bb;
Gaa, H, Q, X, Y, Z, B, and C commands are the same as those in the first embodiment. Ddd is a correction number for instructing an actual tool diameter correction amount, and an actual tool diameter is instructed thereby. Gcc commands the tool radius correction direction. Although the actual tool diameter and the tool diameter correction direction are commanded by a program here, they may be set in parameters or the like.

  Here, the actual tool radius correction amount is R, and the tool radius correction direction is right. As shown in FIG. 9, when focusing on a certain front block and rear block, in a shape in which the movement command of the linear movement axis of the front block and the rear block is projected on a plane perpendicular to the direction of the tool posture command in the front block command. The intersection calculation is performed on the offset path that is R apart to the right with respect to the movement shape of the linear movement axis of the previous block and the offset path that is R to the right of the movement shape of the linear movement axis of the rear block. A technique of creating a vector from the movement axis end point position to the intersection as a tool radius correction vector is known as three-dimensional tool radius correction. In FIG. 9, the tool diameter is drawn larger than the tool head.

  In the third embodiment, a machining point command sequence is created by setting a position obtained by adding a tool radius correction vector to the linear movement axis end point position of the previous block as a machining point (see FIG. 9). That is, the third embodiment is an embodiment in which tool radius correction is added to the first embodiment. Further, the only difference is that an offset path that is separated by R is created on the left side with respect to the movement command of the linear movement axis if the tool radius correction direction is left.

Embodiment 4
This is explained in the following program command sequence.
<Program command>
G aa G cc H hh Q qq D dd;
X Px1 Y Py1 Z Pz1 B Pb1 C Pc1;
X Px2 Y Py2 Z Pz2 B Pb2 C Pc2;
. . .
X Pxn-2 Y Pyn-2 Z Pzn-2 B Pbn-2 C Pcn-2;
X Pxn-1 Y Pyn-1 Z Pzn-1 B Pbn-1 C Pcn-1;
X Pxn Y Pyn Z Pzn B Pbn C Pcn;
X Pxn + 1 Y Pyn + 1 Z Pzn + 1 B Pbn + 1 C Pcn + 1;
X Pxn + 2 Y Pyn + 2 Z Pzn + 2 B Pbn + 2 C Pcn + 2;
. . .
. . .
G bb;
Gaa, H, Q, X, Y, Z, B, and C commands are the same as those in the first embodiment. Ddd is a correction number for instructing an actual tool diameter correction amount, and an actual tool diameter is instructed thereby. Gcc commands the tool radius correction direction. Although the actual tool diameter and the tool diameter correction direction are commanded by a program here, they may be set in parameters or the like.

  The steps up to obtaining the machining point curve and the reference tool length curve are the same as in the first embodiment. Here, assuming that a function representing a machining point curve is f (t), a machining point derivative f ′ (t) obtained by first-order differentiation of f (t) is generated (see FIG. 10).

  In FIG. 10, the first-order differential value on the machining point curve is drawn as a vector. The machining point curve f (t) is a function representing a position, but the machining point derivative f ′ (t) is a derivative thereof and is not the same dimension. However, for the sake of convenience, in FIG. 10, an image having virtually the same dimension is drawn as a dotted line shape connecting the tips of the first-order differential vectors. Similarly, when g (t) is a function representing the reference tool length position curve, a reference tool length position derivative g ′ (t) obtained by first-order differentiation of g (t) is generated (see FIG. 11).

  Similar to FIG. 10, in FIG. 11, the primary differential value on the reference tool length position curve is drawn as a vector. The reference tool length position curve g (t) is a function representing the position, but the reference tool length position derivative g ′ (t) is a derivative thereof and is not the same dimension. However, for the sake of convenience, in FIG. 11, an image having virtually the same dimension is depicted as a dotted line shape connecting the tips of the first-order differential vectors.

  Next, a method for obtaining the movement position of each axis from these data will be described with reference to FIG. In FIG. 12, the tool diameter is drawn large for easy understanding. The obtained machining point curve and the reference tool length position curve are interpolated at fixed intervals, and an interpolation machining position Cp (Cpx, Cpy, Cpz) and an interpolation reference tool length position Sp (Spx, Spy, Spz) in each interpolation cycle are obtained. . From the interpolation machining position Cp and the interpolation reference tool length position Sp, an interpolation tool posture Tp (Tpx, Tpy, Tpz) is obtained by Equation (4). These points are the same as in the first embodiment.

  Further, the machining point derivative f ′ (t) and the reference tool length position derivative g ′ (t) are also interpolated, and the machining point tangent vector Vc (Vcx, Vcy, Vcz) and the reference tool length position tangent at each interpolation period, respectively. A vector Vs (Vsc, Vsy, Vsz) is calculated and obtained. The machining point tangent vector Vc and the reference tool length position tangent vector Vs are obtained as unit vectors Uc (Ucx, Ucy, Ucz) and Us (Usx, Usy, Usz), respectively, using Equation 7.

  When the tool radius correction direction is on the right side, assuming that the actual tool radius correction amount is Ra, the radius correction interpolation machining position Cc and the radius correction interpolation reference tool length position Sc are calculated according to equation (8). Here, the symbol “x” represents an outer product.

  The diameter correction interpolation machining position Cc is substituted into the interpolation machining position Cp, and the diameter correction interpolation reference tool length position Sc is substituted into the interpolation reference tool length position Sp according to equation (9).

Then, the tool posture is again obtained from the new interpolation machining position Cp and the new interpolation reference tool length position Sp by the equation (4), and is set as an interpolation tool posture Tp (Tpx, Tpy, Tpz).
Then, the position (X, Y, Z) of the linear movement axis and the rotational movement are obtained from the new interpolation tool posture Tp, the new interpolation processing position Cp, and the actual tool length La commanded by the program command Hhh, using Equation (5). An axis position (B, C) is generated. B and C generally have a plurality of solutions, but selecting a solution close to the command values Pbi and Pci of B and C in the block command of the block being interpolated and moving to the generated axis position The same as in the first embodiment. Further, if the tool radius correction direction is left, the order of the outer product of Formula 8 is changed back and forth as in Formula 10, and the only difference is that a vector based on the outer product is created on the left in the traveling direction.

Embodiment 5
The steps up to obtaining the program command and the machining point curve and the reference tool length curve are the same as in the fourth embodiment. In the fifth embodiment, the machining point tangent vector Vc is obtained from the interpolation machining position in the interpolation cycle and the interpolation machining position in the past interpolation cycle.

  As one method, it is obtained as shown in Equation 11. The difference between the interpolation processing position Cp in the interpolation cycle and the interpolation processing position Cq in the previous interpolation cycle is used. Similarly, the reference tool length position tangent vector Vs is set as a difference between the interpolation reference tool length position Sp in the interpolation cycle and the interpolation reference tool length position Sq in the previous interpolation cycle.

As another method, the machining point tangent vector Vc is set as the difference between the interpolation machining position Cp in the interpolation cycle and the average position Ca of the interpolation machining positions in the past interpolation cycle, and similarly, the reference tool length position tangent vector Vs is used as the difference. A difference between the interpolation reference tool length position Sp in the interpolation cycle and the average position Ca of the interpolation machining positions in a plurality of past interpolation cycles can also be used.
If there is no past interpolation at the start of the interpolation, the machining position and the interpolation reference tool length position in the previous interpolation cycle, that is, the interpolation reference tool length position in the previous interpolation cycle, that is, the start The machining position at the time and the interpolation reference tool length position may be used.

  Then, once the machining point tangent vector Vc and the reference tool length position tangent vector Vs are obtained, the machining point tangent vector Vc and the reference tool length position tangent vector Vs are respectively obtained as unit vectors Uc (Ucx, Ucy, Ucz) and Us (Usx, Usy, Usz), the radius correction interpolation machining position Cc and the radius correction interpolation reference tool length position Sc are calculated, and the radius correction interpolation machining position Cc is substituted into the interpolation machining position Cp to correct the radius. By substituting the interpolation reference tool length position Sc into the interpolation reference tool length position Sp, the tool posture is again obtained from these new interpolation processing position Cp and the new interpolation reference tool length position Sp by Equation 4, and is set as the interpolation tool posture Tp. From the new interpolation tool posture Tp, the new interpolation machining position Cp, and the actual tool length La commanded by the program command Hhh, Position of the movement axis (X, Y, Z) and the position of the rotational movement shaft (B, C) to produce a.

As is clear from the above description of the embodiments of the present invention, numerical values for controlling a machine tool having a rotating shaft so that the machining point moves on a smooth curve and the reference tool length position changes smoothly according to the present invention. A control device can be provided.
Since the machining surface is a curved surface sandwiched between a smooth curve where the machining point moves and a curve where the reference tool length position moves smoothly, there is a guarantee that the machining surface itself will be a smooth curve. For example, thin and high smooth sides such as aircraft wing ribs are usually machined on the tool side. In such a case, a smooth machined surface can be obtained by the present invention.

  FIG. 14 is a principal block diagram of an embodiment of a numerical control apparatus for carrying out the present invention. A processor (CPU) 20 for overall control of the numerical control device 100 is connected to a memory 21 composed of ROM, RAM, nonvolatile memory, and the like, and an interface 22 connected to a data input / output device 36 for inputting / outputting data to / from a storage medium. , Interface 25 to which display / MDI unit 32 is connected, interface 26 to which operation panel 33 is connected, PMC (programmable machine controller) 23, display / MDI unit 32, and each axis control circuit for controlling each axis 27, a spindle control circuit 29 is connected via a bus 31.

  In this embodiment, the 5-axis machine is controlled by the numerical control device 100, and the X axis, the Y axis, and the Z axis of the linear axis, and the B (A) axis and the C axis of the rotation axis Means for controlling. Each axis control circuit 27 for each of the five axes receives a movement command amount from the processor 20 and outputs a command for each axis to the servo amplifier 28. The servo amplifier 28 for each axis receives this command and drives the servo motor 34 for each axis. Each axis servo motor 34 has a built-in position / velocity detector, and feeds back a position / velocity feedback signal from the position / velocity detector to each axis control circuit 27 to perform position / velocity feedback control. In FIG. 14, description of position / speed feedback is omitted.

  The spindle control circuit 29 receives a spindle rotation command and outputs a spindle speed signal to the spindle amplifier 30 based on the command spindle speed and a speed feedback signal from a position coder provided in the spindle motor 35. The spindle amplifier 30 controls the speed of the spindle motor 35, which is the main shaft, based on the spindle speed signal.

  It is assumed that a machining program created using a CAD / CAM device, a copying device, or the like is input from the data input / output device 36 via an interface and stored in a nonvolatile memory portion constituting the memory 21.

FIG. 15 is a flowchart showing a processing algorithm in interpolation. It demonstrates according to each step.
[Step ST1] A machining point curve is interpolated to obtain an interpolation machining position.
[Step ST2] The reference tool length position curve is interpolated to obtain the interpolation reference tool length position.
[Step ST3] An interpolation tool posture is obtained from Equation 4 from the interpolation processing position and the interpolation reference tool length position.
[Step ST4] From the interpolation tool posture, the interpolation machining position, and the actual tool length correction amount, the positions of the linear movement axis and the rotation movement axis are generated by Equation 5, and the process ends.

It is a functional block diagram of the outline of the numerical control apparatus for machine tools which has a rotating shaft of this invention. It is a schematic block diagram of a tool head rotary machine. It is a figure which shows a process point command sequence. It is a figure explaining obtaining a corrected machining point sequence corresponding to a machining point command sequence by moving the machining point command sequence toward the closest position on the machining point approximate curve within a first set tolerance amount. It is a figure explaining obtaining | requiring the cubic polynomial curve between the correction process points Qn and Qn + 1. It is a figure explaining calculating | requiring a process point curve by combining a cubic polynomial curve. It is a figure explaining producing | generating a smooth reference | standard tool length position curve with respect to a reference | standard tool length position row | line | column. It is a figure explaining the movement to the produced | generated axial position. It is a figure explaining producing a processing point command sequence by making a processing point a position which added a tool radius correction vector to a linear movement axis end point position of a previous block. It is a figure explaining producing | generating the machining point derivative f '(t) which carried out the primary differentiation of f (t), if the function showing a machining point curve is set to f (t). FIG. 6 is a diagram for explaining the generation of a reference tool length position derivative g ′ (t) obtained by first-order differentiation of g (t), where g (t) is a function representing a reference tool length position curve. It is a figure explaining the method of calculating | requiring the movement position of each axis | shaft. It is a figure explaining how to obtain the machining point tangent vector Vc and the reference tool length position tangent vector Vs. It is a principal part block diagram of one Embodiment of the numerical control apparatus which implements this invention. It is a flowchart which shows the algorithm of the process in interpolation.

Explanation of symbols

1 Program reading means 2 Block analysis 3 Interpolation 4x X-axis servo 4y Y-axis servo 4z Z-axis servo 4B (A) B (A) -axis servo 4C C-axis servo 5 Correction amount command means 6 Machining point curve generation means 7 Reference tool length Position sequence generation means 8 Reference tool length position curve generation means 9 Interpolation position calculation means 10 Interpolation tool attitude calculation means 11 Axis position generation means Pn Machining point command position Pbn B axis command position Pcn C axis command position Ln Actual tool length Cp Interpolation processing Position Sp Interpolation reference tool length position R Actual tool radius compensation amount f (t) Machining point curve f '(t) Machining point derivative g (t) Reference tool length position curve g' (t) Reference tool length position derivative

Claims (10)

In a numerical control apparatus for controlling a machine tool having at least one linear movement axis and at least one rotation movement axis, and continuously machining a workpiece fixed on a table with a tool,
Correction amount command means for commanding or setting the actual tool length correction amount and the reference tool length correction amount,
Command sequence creating means for reading blocks continuously commanded on the machining program and creating a machining point command sequence and a tool posture command sequence;
Machining point curve generating means for generating a smooth machining point curve from the machining point command sequence;
A tool posture unit vector sequence is calculated from the tool posture command sequence, the reference tool length correction amount is added to the tool posture unit vector sequence to obtain a reference tool length vector sequence, and the reference tool length vector sequence is calculated as the machining point. A reference tool length position sequence generating means for generating a reference tool length position sequence by adding to the command sequence;
A reference tool length position curve generating means for generating a smooth reference tool length position curve from the reference tool length position sequence;
Interpolation position calculation means for interpolating the machining point curve and the reference tool length position curve every predetermined period, and obtaining an interpolation machining position and an interpolation reference tool length position in each interpolation period;
Interpolation tool posture calculation means for obtaining an interpolation tool posture from the interpolation processing position obtained by the interpolation position calculation means and the interpolation reference tool length position;
Axis position generating means for generating the axis position of the linear movement axis and the axis position of the rotational movement axis from the interpolation tool posture, the interpolation processing position, and the actual tool length correction amount;
An axis moving means for moving to the generated axis position;
A numerical control device for a machine tool having a rotating shaft.   The machining point curve generating means generates a machining point approximate curve based on the machining point command sequence, and the machining point command sequence is within a first set tolerance amount toward the closest position on the machining point approximate curve. 2. The rotation axis according to claim 1, wherein a correction machining point sequence corresponding to the machining point command sequence is obtained by moving at a step, and the machining point curve is obtained as a curve passing through the correction processing point sequence. Numerical control device for machine tools.   The machine point curve generating means obtains the machining point curve as a curve passing through the machining point command sequence based on the machining point command sequence, for machine tools having a rotating shaft according to claim 1. Numerical control unit.   The reference tool length position curve generating means generates a reference tool length position approximate curve based on the reference tool length position sequence, and sets the reference tool length position sequence to the closest position on the reference tool length position approximate curve. By moving within the second set tolerance amount, a corrected reference tool length position row corresponding to the reference tool length position row is obtained, and the reference tool length position curve is obtained as a curve passing through the corrected reference tool length position row. A numerical control device for a machine tool having a rotating shaft according to claim 1.   2. The rotating shaft according to claim 1, wherein the reference tool length position curve generating unit obtains the reference tool length position curve as a curve passing through the reference tool length position sequence based on the reference tool length position sequence. Numerical control device for machine tools having   The numerical control device for a machine tool having a rotating shaft according to any one of claims 1 to 5, wherein the tool posture command sequence is commanded by a position of two rotational movement shafts.   The numerical control device for a machine tool having a rotating shaft according to any one of claims 1 to 5, wherein the tool posture command sequence is commanded as a tool posture vector. The correction amount command means also commands or sets an actual tool radius correction amount and a tool radius correction direction,
The command sequence creation means obtains a tool radius correction vector at the end point of the front block from the preceding and following front block commands, the back block command, the actual tool radius correction amount and the tool radius correction direction, and the linear movement axis end position of the front block A machine tool having a rotating shaft according to any one of claims 1 to 7, wherein a machining point command sequence is created by setting a position obtained by adding the tool radius correction vector to a machining point. Numerical control unit. The correction amount command means also commands or sets an actual tool radius correction amount and a tool radius correction direction,
The machining point curve generating means also generates a machining point derivative obtained by first-order differentiation of a function representing the machining point curve,
The reference tool length position curve generating means also creates a reference tool length position derivative obtained by first-order differentiation of a function representing the reference tool length position curve,
The interpolation position calculation means calculates a machining point tangent vector and a reference tool length position tangent vector by interpolating the machining point derivative and the reference tool length position derivative,
The interpolation tool posture calculation means includes the interpolation tool posture, the machining point tangent vector, the reference tool length position tangent vector, the actual tool radius correction amount and the radius correction interpolation position and the radius correction interpolation reference from the tool radius correction direction. A tool length position is calculated, the radius correction interpolation machining position is substituted into the interpolation machining position, the radius correction interpolation reference tool length position is substituted into the interpolation reference tool length position, and the interpolation machining position and the interpolation reference tool length position are substituted. 8. The numerical control device for a machine tool having a rotating shaft according to claim 1, wherein the tool posture is obtained again from the first position and substituted into the interpolation tool posture. The correction amount command means also commands or sets an actual tool radius correction amount and a tool radius correction direction,
The interpolation position calculation means includes a machining point tangent vector and a reference tool length position based on the interpolation machining position, the interpolation reference tool length position, the interpolation machining position in a past interpolation cycle, and the interpolation reference tool length position in a past interpolation cycle. Compute the tangent vector,
The interpolation tool posture calculation means includes the interpolation tool posture, the machining point tangent vector, the reference tool length position tangent vector, the actual tool radius correction amount and the radius correction interpolation position and the radius correction interpolation reference from the tool radius correction direction. A tool length position is calculated, the radius correction interpolation machining position is substituted into the interpolation machining position, the radius correction interpolation reference tool length position is substituted into the interpolation reference tool length position, and the interpolation machining position and the interpolation reference tool length position are substituted. 8. The numerical control device for a machine tool having a rotating shaft according to claim 1, wherein the tool posture is obtained again from the first position and substituted into the interpolation tool posture.

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