JP2017102594A - Control device, machining tool, control method and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device, machining tool, control method and computer program that can form smooth curved surfaces on works.SOLUTION: In a control device setting a machining route based on a plurality of command points instructing a position of a main shaft, and controlling a movement of the main shaft on the basis of the machining route, the control device comprises: an evaluation cross section setting unit that sets an evaluation cross section so as to be vertical to the machining route, in which the machining route is shaped into an annular shape; a computation unit that computes a cross point of the evaluation cross section set by the evaluation cross section setting unit and the machining route; a cross point position correction unit that corrects a position of the cross point computed by the computation unit; and a command point position correction unit that corrects a position of the command point in a direction crossing the machining route on the basis of the cross point corrected by the cross point position correction unit.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a control device, a machine tool, a control method, and a computer program for controlling movement of a spindle on which a tool is mounted.

  The machine tool includes a control device that controls movement of a spindle on which a tool is mounted. The control device sets a plurality of command points that indicate the position of the spindle and sets a machining path. When the tool mounted on the spindle forms a three-dimensional curved surface on the workpiece, the control device calculates and generates a plurality of curves in which minute line segments between command points are continuous.

  For example, a plurality of curves are generated on a plane (horizontal plane) parallel to the front-rear direction and the left-right direction. The plurality of curves are arranged in the front-rear direction or the left-right direction. The control device sets a vertical position for each curve. Further, the control device interpolates the generated curve based on a smooth curve such as a spline curve or a Bezier curve because a sharp portion appears at the joint of the minute line segment. At each set vertical position, the main axis moves along the interpolated curve to process the workpiece (see, for example, Patent Document 1).

Japanese Patent No. 3466111

  However, even when the above-described interpolation is performed, a scale-like pattern appears on the workpiece surface due to a difference in slope between adjacent curves, a quantization error generated by calculation in the control device, and the like. In Patent Document 1, command points are inserted so as to form a smooth line between the command points without correcting the command points. Therefore, although the command point itself is wrong, it passes through the command point, and there is a problem that a scale-like pattern appears on the surface of the workpiece.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a control device, a machine tool, a control method, and a computer program that can form a smooth curved surface on a workpiece.

  A control device according to the present invention sets a machining path based on a plurality of command points that indicate a position of a spindle, and controls the movement of the spindle based on the machining path. An evaluation cross-section setting unit that sets an evaluation cross-section so as to be perpendicular to the machining path, a calculation unit that calculates an intersection of the evaluation cross-section set by the evaluation cross-section setting unit and the machining path, and the calculation An intersection position correcting unit that corrects the position of the intersection calculated by the unit, and a command point position correcting unit that corrects the position of the command point in the direction intersecting the machining path based on the intersection corrected by the intersection position correcting unit It is characterized by providing.

  In the control device according to the present invention, the machining path includes an annular first path part and an annular second path part positioned inside the first path part, and the evaluation cross-section setting part A first reference point setting unit for setting a first reference point on the first path unit, and a second reference point on the second path unit and closest to the first reference point And a second reference point setting unit for calculating the evaluation cross section based on the first reference point and the second reference point.

  In the control device according to the present invention, the machining path includes a plurality of path parts including the first path part and the second path part, and the first path part is located on the outermost side in the plurality of path parts. In the plurality of path portions, the second path portion is located on the innermost side.

  In the control device according to the present invention, the machining path has a spiral shape, and the plurality of command points include a start point command point located at a start point of the machining path and an end point command point located at an end point of the machining path, A start-point-side path unit setting unit that sets one of the first path unit and the second path unit between the start-point command point and the first command point different from the start-point command point; and the end-point command point And an end point side path part setting unit that sets the other of the first path part or the second path part between the second command point different from the end point command point.

  A machine tool according to the present invention includes any one of the control devices described above and the spindle.

  A control method according to the present invention sets a machining path based on a plurality of command points that indicate the position of a spindle, and controls the movement of the spindle based on the machining path. The evaluation cross section is set to be perpendicular to the machining path, the intersection of the set evaluation cross section and the machining path is calculated, the position of the calculated intersection is corrected, based on the corrected intersection, The position of the command point in a direction intersecting the machining path is corrected.

  The computer program according to the present invention can be executed by a control device that sets a machining path based on a plurality of command points for instructing the position of the spindle according to the machining program and controls the movement of the spindle based on the machining path. An evaluation cross section setting unit that sets an evaluation cross section so that the processing path is perpendicular to the processing path, and an evaluation set by the evaluation cross section setting unit A processing unit that calculates the intersection of the cross section and the machining path, an intersection position correction unit that corrects the position of the intersection calculated by the calculation unit, and an intersection point corrected by the intersection position correction unit intersects the processing path. It is made to function as a command point position correction part which corrects the position of the command point in the direction.

  In the present invention, the evaluation cross section is set to be perpendicular to the annular machining path, the position of the intersection of the evaluation cross section and the machining path is corrected, and the machining path is crossed based on the corrected position of the intersection. Correct the position of the command point in the direction.

  In the present invention, the first reference point and the second reference point are set in the first path portion on the outer peripheral side and the second path portion on the inner peripheral side, respectively. The second reference point is located closest to the first reference point. By setting the evaluation cross section so that the first reference point and the second reference point are located on the evaluation cross section, the evaluation cross section becomes substantially perpendicular to the machining path.

  In the present invention, it is possible to prevent the evaluation cross sections from intersecting when the first path portion is positioned on the outermost peripheral side and the second path portion is positioned on the innermost peripheral side.

  In the present invention, one of the first path portion and the second path portion is located on the start point side of the machining path, and the other is located on the end point side of the machining path. When the starting point is located at the center of the spiral machining path, the first path part is located on the end point side, and the second path part is located on the start point side. When the end point is located at the center of the machining path, the second path part is located on the end point side, and the first path part is located on the start point side.

  In the control device, machine tool, control method, and computer program according to the present invention, the evaluation cross section is set to be perpendicular to the annular machining path, and the position of the intersection of the evaluation cross section and the machining path is corrected. The position of the command point in the direction intersecting the machining path is corrected based on the corrected position of the intersection. When multiple evaluation sections are set to extend radially from the center of the processing path for an annular processing path, the evaluation section has a high density portion and a low density portion, and the correction accuracy for the command point decreases. There are things to do. In the present invention, by making the evaluation cross section perpendicular to the machining path, it is possible to prevent a reduction in correction accuracy with respect to the command point even if a difference occurs in the density of the evaluation cross section.

1 is a perspective view schematically showing a machine tool. It is a block diagram which briefly shows the structure of a control apparatus. It is a top view which shows schematically the processing path with respect to a workpiece | work, and evaluation cross section. It is a perspective view which briefly shows the evaluation section to a work. It is a flowchart explaining the process route setting process by a control apparatus. It is a flowchart explaining an outermost periphery / innermost periphery calculation process. FIG. 5 is a schematic view schematically showing a machining path of a main shaft moving in a spiral shape from the outer peripheral side to the inner peripheral side. FIG. 5 is a schematic view schematically showing a machining path of a main shaft moving in a spiral shape from the inner peripheral side to the outer peripheral side. It is a flowchart explaining an evaluation cross-section setting process. It is a schematic diagram explaining an evaluation cross-section setting process. It is a schematic diagram which shows a command point and the intersection of an evaluation cross section and a process path | route schematically. It is a conceptual diagram which shows an example of an intersection table. It is explanatory drawing explaining the 1st correction method of the intersection position on an evaluation cross section. It is explanatory drawing explaining the 2nd correction method of the intersection position on an evaluation cross section. It is explanatory drawing explaining the correction method of a command point. It is a flowchart explaining a command point position correction process.

  Hereinafter, the present invention will be described based on the drawings showing a machine tool according to an embodiment. In the following description, up and down, left and right, and front and rear indicated by arrows in the figure are used. FIG. 1 is a perspective view schematically showing a machine tool.

  The machine tool 100 includes a rectangular base 1 extending forward and backward. A work holding unit 3 that holds a work is provided on the front side of the upper portion of the base 1. The work holding unit 3 can rotate around the A axis with the left-right direction as the axial direction and the C axis with the up-down direction as the axial direction.

  A support base 2 for supporting a column 4 described later is provided on the rear side of the upper part of the base 1. A Y-axis direction moving mechanism 10 for moving the moving plate 16 in the front-rear direction is provided on the support base 2. The Y-axis direction moving mechanism 10 includes two rails 11 extending in the front-rear direction, a Y-axis screw shaft 12, a Y-axis motor 13, and a bearing 14.

  The rails 11 are provided on the left and right of the upper part of the support base 2, respectively. The Y-axis screw shaft 12 extends in the front-rear direction and is provided between the two rails 11. A bearing 14 is provided at each of the front end portion and the middle portion of the Y-axis screw shaft 12. In addition, illustration of the bearing provided in the middle part is abbreviate | omitted. The Y-axis motor 13 is connected to the rear end portion of the Y-axis screw shaft 12.

  A nut (not shown) is screwed onto the Y-axis screw shaft 12 via a rolling element (not shown). The rolling element is, for example, a ball. A plurality of sliders 15 are slidably provided on each rail 11. A moving plate 16 is connected to the upper part of the nut and the slider 15. The moving plate 16 extends in the horizontal direction. As the Y-axis motor 13 rotates, the Y-axis screw shaft 12 rotates, the nut moves in the front-rear direction, and the moving plate 16 moves in the front-rear direction.

  An X-axis direction moving mechanism 20 that moves the column 4 in the left-right direction is provided on the upper surface of the moving plate 16. The X-axis direction moving mechanism 20 includes two rails 21 extending left and right, an X-axis screw shaft 22, an X-axis motor 23 (see FIG. 2), and a bearing 24.

  The rails 21 are provided at the front and rear sides of the upper surface of the movable plate 16. The X-axis screw shaft 22 extends left and right and is provided between the two rails 21. A bearing 24 is provided at each of the left end portion and midway portion of the X-axis screw shaft 22. In addition, description of the bearing provided in the middle part of the X-axis screw shaft 22 is abbreviate | omitted. The X-axis motor 23 is connected to the rear end portion of the X-axis screw shaft 22.

  A nut (not shown) is screwed onto the X-axis screw shaft 22 via a rolling element (not shown). Grease is applied to the X-axis screw shaft 22. A plurality of sliders 26 are slidably provided on each rail 21. The column 4 is connected to the upper part of the nut and the slider 26. Column 4 is columnar. As the X-axis motor 23 rotates, the X-axis screw shaft 22 rotates, the nut moves in the left-right direction, and the column 4 moves in the left-right direction.

  A Z-axis direction moving mechanism 30 for moving the spindle head 5 in the vertical direction is provided on the front surface of the column 4. The Z-axis direction moving mechanism 30 includes two rails 31 extending vertically, a Z-axis screw shaft 32, a Z-axis motor 33, and a bearing 34.

  The rails 31 are provided on the left and right sides of the front surface of the column 4, respectively. The Z-axis screw shaft 32 extends vertically and is provided between the two rails 31. A bearing 34 is provided at each of a lower end portion and a midway portion of the Z-axis screw shaft 32. In addition, illustration of the bearing provided in the middle part is abbreviate | omitted. The Z-axis motor 33 is connected to the upper end portion of the Z-axis screw shaft 32.

  A nut (not shown) is screwed onto the Z-axis screw shaft 32 via a rolling element (not shown). Grease is applied to the Z-axis screw shaft 32. A plurality of sliders 35 are slidably provided on each rail 31. The spindle head 5 is connected to the front part of the nut and the slider 35. The Z-axis screw shaft 32 is rotated by the rotation of the Z-axis motor 33, the nut moves in the vertical direction, and the spindle head 5 moves in the vertical direction. The Z-axis motor 33, the Z-axis screw shaft 32, the nut and the rolling element constitute a ball screw mechanism.

  A main shaft 5 a extending vertically is provided in the main shaft head 5. The main shaft 5a rotates around the axis. A spindle motor 6 is provided at the upper end of the spindle head 5. A tool is attached to the lower end of the main shaft 5a. The spindle 5a is rotated by the rotation of the spindle motor 6, and the tool is rotated. The rotated tool processes the workpiece held in the workpiece holding unit 3.

  The machine tool 100 includes a tool changer (not shown) that changes tools. The tool changer exchanges a tool housed in a tool magazine (not shown) and a tool mounted on the spindle 5a.

FIG. 2 is a block diagram schematically showing the configuration of the control device 50. The control device 50 includes a CPU 51, a storage unit 52, a RAM 53, and an input / output interface 54. The storage unit 52 is a rewritable memory, such as an EPROM or an EEPROM. The storage unit 52 stores an intersection point table, a route number i, a command point P _k , an intersection point S _i ^d , a final number of k, a route A, a route B, a first reference point O _m , a second reference point L _m , and the like. Store (d, i, k, m are natural numbers).

  When the operator operates the operation unit 7, a signal is input from the operation unit 7 to the input / output interface 54. The operation unit 7 is a keyboard, a button, a touch panel, or the like, for example. The input / output interface 54 outputs a signal to the display unit 8. The display unit 8 displays characters, figures, symbols, and the like. The display unit 8 is, for example, a liquid crystal display panel.

  The control device 50 includes an X-axis control circuit 55 corresponding to the X-axis motor 23, a servo amplifier 55a, and a differentiator 23b. The X-axis motor 23 includes an encoder 23a. The X-axis control circuit 55 outputs a command indicating the amount of current to the servo amplifier 55a based on a command from the CPU 51. The servo amplifier 55a receives the command and outputs a drive current to the X-axis motor 23.

  The encoder 23 a outputs a position feedback signal to the X-axis control circuit 55. The X-axis control circuit 55 performs position feedback control based on the position feedback signal.

  The encoder 23a outputs a position feedback signal to the differentiator 23b, and the differentiator 23b converts the position feedback signal into a speed feedback signal and outputs it to the X-axis control circuit 55. The X-axis control circuit 55 performs speed feedback control based on the speed feedback signal.

  The current detector 55b detects the value of the drive current output from the servo amplifier 55a. The current detector 55 b feeds back the value of the drive current to the X axis control circuit 55. The X axis control circuit 55 executes current control based on the value of the drive current.

  The control device 50 includes a Y-axis control circuit 56 corresponding to the Y-axis motor 13, a servo amplifier 56a, and a differentiator 13b. The Y-axis motor 13 includes an encoder 13a. Based on the command from the CPU 51, the Y-axis control circuit 56 outputs a command indicating the current amount to the servo amplifier 56a. The servo amplifier 56 a receives the command and outputs a drive current to the Y-axis motor 13.

  The encoder 13 a outputs a position feedback signal to the Y-axis control circuit 56. The Y-axis control circuit 56 performs position feedback control based on the position feedback signal.

  The encoder 13a outputs a position feedback signal to the differentiator 13b, and the differentiator 13b converts the position feedback signal into a speed feedback signal and outputs it to the Y-axis control circuit 56. The Y-axis control circuit 56 executes speed feedback control based on the speed feedback signal.

  The current detector 56b detects the value of the drive current output from the servo amplifier 56a. The current detector 56 b feeds back the drive current value to the Y-axis control circuit 56. The Y axis control circuit 56 executes current control based on the value of the drive current.

  The control device 50 includes a Z-axis control circuit 57 corresponding to the Z-axis motor 33, a servo amplifier 57a, and a differentiator 33b. The Z-axis motor 33 includes an encoder 33a. Based on the command from the CPU 51, the Z-axis control circuit 57 outputs a command indicating the amount of current to the servo amplifier 57a. The servo amplifier 57a receives the command and outputs a drive current to the Z-axis motor 33.

  The encoder 33 a outputs a position feedback signal to the Z-axis control circuit 57. The Z-axis control circuit 57 performs position feedback control based on the position feedback signal.

  The encoder 33a outputs a position feedback signal to the differentiator 33b, and the differentiator 33b converts the position feedback signal into a speed feedback signal and outputs it to the Z-axis control circuit 57. The Z-axis control circuit 57 performs speed feedback control based on the speed feedback signal.

  The current detector 57b detects the value of the drive current output from the servo amplifier 57a. The current detector 57 b feeds back the value of the drive current to the Z-axis control circuit 57. The Z-axis control circuit 57 executes current control based on the drive current value.

  The control device 50 also performs feedback control similar to that of the X to Z axis motors 23, 13, and 33 with respect to the spindle motor 6.

  The machine tool 100 includes a magazine motor 60 and a magazine control circuit 58. The tool magazine is driven by the rotation of the magazine motor 60. The magazine control circuit 58 controls the rotation of the magazine motor 60.

The storage unit 52 stores a machining program for machining a workpiece. The machining program has a plurality of command points P _k that indicate the position of the spindle 5a. k indicates the order of instructions constituting the machining program. The spindle 5a sequentially moves a plurality of command points _Pk , and the tool mounted on the spindle 5a processes the workpiece.

The storage unit 52 stores a command point P _k in advance. The control device 50 sets a path (machining path) along which the spindle 5a moves based on the plurality of command points _Pk . The control device 50 executes the movement of the main shaft 5a based on the machining path.

  A processing path setting method will be described. FIG. 3 is a plan view schematically showing a machining path and an evaluation cross section for the work, and FIG. 4 is a perspective view schematically showing an evaluation cross section for the work. In the figure, the X direction indicates the left-right direction, the Y direction indicates the front-rear direction, and the Z direction indicates the up-down direction. Moreover, the shape of the workpiece | work in FIG.3 and FIG.4 has shown the shape after a process.

The control device 50 sets an evaluation section D ^d (d indicates a section number and is a natural number) for the workpiece. For example, as shown in FIG. 3, when the main shaft 5 a moves in a spiral, the machining path is a path along the spiral direction. As shown in FIG. 3, the control device 50 sets a plurality of evaluation sections D ^d along a direction substantially orthogonal to the machining path. The plurality of evaluation sections are arranged in the circumferential direction of the machining path. The operator instructs in advance that the direction of the machining path is the circumferential direction.

  The control device 50 executes a machining path setting process. FIG. 5 is a flowchart for explaining the machining path setting process by the control device 50.

  The CPU 51 of the control device 50 stands by until a start signal is input (step S1: NO). For example, the user operates the operation unit 7 to input a start signal to the control device.

  When the start signal is input (step S1: YES), the CPU 51 executes the outermost / innermost circumference calculation process (step S2), the evaluation cross-section setting process (step S3), and the command point position. A correction process is executed (step S4). Details of the outermost / innermost circumference calculation process, the evaluation cross-section setting process, and the command point position correction process will be described later.

  The outermost / innermost circumference calculation process will be described. 6 is a flowchart for explaining the outermost / innermost circumference calculation process, FIG. 7 is a schematic view schematically showing the machining path of the spindle 5a moving from the outer circumference side to the inner circumference side in a spiral shape, and FIG. It is a schematic diagram which shows schematically the processing path of the main axis | shaft 5a which moves to the outer peripheral side from an inner peripheral side in a shape.

The CPU 51 sequentially identifies identifiers (numbers) for a plurality of command points P _{k from} a command point (start point command point) P ₁ located at the start point of the machining path to a command point (end point command point) P _N located at the end point of the machining path. Is set (step S11).

The CPU 51 calculates the line segment P _a P _{a + 1} that is closest to the start point command point P ₁ (step S12), and calculates the line segment P _b P _{b + 1} that is closest to the end point command point P _N (step S13). .

CPU51 sets the machining path between the start command point P ₁ and the command point P _a to the route A (step S14), and the machining path between the endpoints command point P _N and the command point P _b on the path B Set (step S15).

As shown in FIG. 7, when the main shaft 5a moves from the outer peripheral side to the inner peripheral side, the path A is positioned on the outermost side and the path B is positioned on the innermost side. As shown in FIG. 8, when the main shaft 5a moves from the inner circumference side to the outer circumference side, the path A is located on the innermost side and the path B is located on the outermost side. Each of the path A and the path B has a substantially circular shape. The annular shape includes a spiral shape as shown in FIG. The calculation of the nearest line segment P _a P _{a + 1} is performed by calculating the shortest distance from the start point command point P ₁ to each line segment P ₂ P ₃ , P ₃ P ₄ ,..., And gradually from the maximum value of the shortest distance. The line segment of the minimum distance when it becomes small is calculated. The same applies to the calculation of the nearest line segment P _b P _{b + 1} .

CPU51 has the minimum value A _{x_min} and the maximum value A _{X_max} the X direction of the path A, and calculates the minimum value A _{Y_min} and the maximum value A _{Y_max} the Y direction (step S16).

CPU51 is the minimum value B _{x_min} and the maximum value B _{X_max} in the X direction of the path B, and calculating the minimum value B _{Y_min} and the maximum value B _{Y_max} the Y direction (step S17).

The CPU 51 determines whether or not A _{X_min} <B _{X_min} <B _{X_max} <A _{X_max} and A _{Y_min} <B _{Y_min} <B _{Y_max} <A _{Y_max} (step S18). When A _{X_min} <B _{X_min} <B _{X_max} <A _{X_max} and A _{Y_min} <B _{Y_min} <B _{Y_max} <A _{Y_max} (step S18: YES), the CPU 51 determines the route A as the outermost peripheral route located on the outermost side. Then, the route B is determined as the innermost peripheral route located on the innermost side (see step S19, FIG. 7), and the process is returned to the evaluation section setting process (see step S3, FIG. 5).

If A _{X_min} <B _{X_min} <B _{X_max} <A _{X_max} and A _{Y_min} <B _{Y_min} <B _{Y_max} <A _{Y_max} (step S18: NO), the CPU 51 determines that B _{X_min} <A _{X_min} <A _{X_max} <B _{X_max} and B _{Y_min} < It is determined whether A _{Y_min} <A _{Y_max} <B _{Y_max} (step S20).

When B _{X_min} <A _{X_min} <A _{X_max} <B _{X_max} and B _{Y_min} <A _{Y_min} <A _{Y_max} <B _{Y_max} (step S20: YES), the CPU 51 determines the path A as the innermost circumferential path. Then, the route B is determined to be the outermost route (see step S21, FIG. 8), and the process is returned to the evaluation cross-section setting process (see step S3, FIG. 5). One of the routes A or B constitutes the first route portion, and the other constitutes the second route portion.

If B _{X_min} <A _{X_min} <A _{X_max} <B _{X_max} and B _{Y_min} <A _{Y_min} <A _{Y_max} <B _{Y_max} are not satisfied (step S20: NO), the CPU 51 notifies an error (step S22) and ends the processing. For example, the display unit 8 displays that an error has occurred in the outermost / innermost circumference calculation process.

After the error notification, when the operator adjusts or changes the data such as setting the command value P _k again and inputs the start signal to the control device 50 again, the CPU 51 calculates the outermost / innermost circumference. You may comprise so that a process may be performed again.

  Next, the evaluation section setting process will be described. FIG. 9 is a flowchart for explaining the evaluation cross-section setting process, and FIG. 10 is a schematic diagram for explaining the evaluation cross-section setting process.

The CPU 51 sets a plurality of first reference points O _m (m is a natural number) spaced equidistantly on the outermost circumference path (step S31), and sets a plurality of second reference points L _m on the innermost circumference path. (Step S32). The first reference points O _m are set at regular intervals in order from the start point command point P ₁ . The setting of the second reference point will be described later.

The CPU 51 sets a point on the innermost circumference path that is closest to the first reference point O _m as the second reference point L _m . The CPU 51 calculates and sets the evaluation cross section D ^d based on the first reference point O _m and the second reference point L _m (step S33). CPU51, as a first reference point O _m and the second reference point L _m is located on the evaluation section D ^d, and calculates an evaluation section D ^d. The CPU 51 returns the process to the command point position correction process (see step S4, FIG. 5). The calculation of the evaluation section D ^d is a plane perpendicular to the XY plane, and a plane including the first reference point O _m and the second reference point L _m is calculated.

Since the second reference point L _m is closest to the first reference point O _m , the evaluation cross section D ^d is substantially perpendicular to the innermost circumference path and the outermost circumference path (processing path).

FIG. 11 is a schematic diagram schematically showing the command point P _k , the evaluation section D ^d, and the intersection of the machining path, and FIG. 12 is a conceptual diagram showing an example of the intersection table. 11 and 12, “i” (i is a natural number) indicates a path number in the circular movement of the main shaft 5a. As shown in FIG. 11, for example, the route with the route number 1 (i = 1) indicates the outermost periphery route, and the route with the route number 2 (i = 2) is an annular shape located inside the route with the route number 1. Indicates the route. The same applies to route numbers 3 and below. The main shaft 5a moves in the order of route numbers.

As shown in FIG. 12, the control device 50 calculates an intersection S _i ^d with the movement path P _k −P _{k + 1} in each evaluation section D ^d , and calculates the path number i, the intersection coordinates S _i ^d, and the movement path. P _k −P _{k + 1} is associated and stored in the intersection table.

Controller 50 corrects the intersection position on the evaluation section D ^d for example, the first correction method. Figure 13 is an explanatory diagram for explaining a first method of correcting the intersection position on the evaluation section D ^d. For example, the controller 50 corrects the coordinates in the Z direction so as to gradually change. Correction point t using the intersection coordinates s _i-2 ^d , s _i-1 ^d , s _{i + 1} ^d , s _{i + 2} ^d of the two points before and after the intersection coordinate S _i ^d to be corrected _i ^d is determined.

Each Z coordinate value of the four intersection coordinates s _i-2 ^d , s _i-1 ^d , s _{i + 1} ^d , s _{i + 2} ^d is expressed as z _i-2 , z _i-1 , z _{i + 1} , z _{i. +2} and the Z coordinate value of the correction point t _i ^d is z _i ′, and the difference between the Z coordinate values is d ₁ = z _i−2 −z _i−1 , d ₂ = z _i−1 −z _{i ′} , d ₃ = z _i ′ −z _{i + 1} , d ₄ = z _{i + 1} −z _{i + 2,} and Z coordinate value double difference d ₁₂ ′, d ₂₃ ′, d ₃₄ ′ (Z coordinate value difference) z _i ′ is calculated such that the difference between d ₁ , d ₂ , d ₃ , and d ₄ ) changes linearly.

The two-time differences d ₁₂ ′, d ₂₃ ′, and d ₃₄ ′ of the Z coordinate value are obtained by the following equations.
d ₁₂ ′ = d ₂ −d ₁ = (z _i−1 −z _i ′) − (z _i−2 −z _i−1 ) = 2 z _i−1 −z _i ′ −z _i−2. 1)
d ₂₃ ′ = d ₃ −d ₂ = (z _i ′ −z _{i + 1} ) − (z _i−1 −z _i ′) = 2 z _i ′ −z _{i + 1} −z _i−1 (2) )
d ₃₄ ′ = d ₄ −d ₃ = (z _{i + 1} −z _{i + 2} ) − (z _i ′ −z _{i + 1} ) = 2 z _{i + 1} −z _{i + 2} −z _i ′ (3)

Since these change linearly,
d ₂₃ ′ = (d ₁₂ ′ + d ₃₄ ′) / 2 (4)
Meet.

Solving z _i ′ based on the equations (1) to (4),
z _i ′ = (− z _i−2 + 4z _i−1 + 4z _{i + 1} −z _{i + 2} ) / 6
It becomes.

Performing the modification for all intersections S _i ^d on evaluation section D ^d. Note that it is also possible to correct only intersections whose Z coordinate values are far apart compared to the Z coordinate values of other intersections.

Controller 50 corrects the intersection position on the evaluation section D ^d for example in the second correction method. FIG. 14 is an explanatory diagram for explaining a second correction method of the intersection position on the evaluation cross section. In FIG. 14, u corresponds to the XY coordinates, and v corresponds to the Z coordinates. The control device 50 creates a smooth curve (spline curve, Bezier curve, NURBS curve, etc.) using, for example, a plurality of other intersections around the intersection S _i ^d to be corrected, Project the intersection S _i ^d to be corrected.

When the four intersections s _i-2 ^d , s _i-1 ^d , s _{i + 1} ^d , s _{i + 2} ^d are used as smooth curves, the section s _i-2 on the evaluation section D ^d (uv plane) ^{d to} s _i-1 ^d , sections s _i-1 ^{d to} s _{i + 1} ^d , sections s _{i + 1} ^{d to} s _{i + 2} ^d , respectively, v ₁ (u), v ₂ (u), v ₃ (u) is represented by the following equation.
v _j (u) = a _j (u−u _j ) ³ + b _j (u−u _j ) ² + c _j (u−u _j ) + d _j
(J = 1, 2, 3)

Based on the fact that the first and second derivatives at the boundary points are continuous, passing through the intersections s _i-2 ^d , s _i-1 ^d , s _{i + 1} ^d , s _{i + 2} ^d 50 can determine a _{j to} d _j .

The selection of the four intersection points is not limited to the case of using two consecutive points located on both sides of the intersection point S _i ^d as described above. For example, intersection points may be selected discontinuously at every two points, such as intersection points s _i-3 ^d , s _i-1 ^d , s _{i + 1} ^d , and s _{i + 3} ^d .

As shown in FIG. 14, the correction point t _i ^d position is a position on the smooth curve where the distance from the intersection S _i ^d to be corrected is minimum.

The corrected intersection group S ^d existing on the d-th evaluation section D ^{d is} defined as T ^d .
T ^d = {t _i ^d | d: section number, i: route number}

The control device 50 corrects the position of the command point by using the intersection point group ^Td . FIG. 15 is an explanatory diagram for explaining a method of correcting a command point. In FIG. 15, P _{a to} P _f indicate command points.

For example, when the command point P _c is a correction target, as shown in FIG. 15A, the command point P _c is located between the cross section D ^d−1 and the cross section D ^d , and the path number is i. The control device 50 refers to the intersection table described above, and acquires the cross-sectional position and path number regarding the command point _Pc .

As shown in FIG. 15B, the control device 50 detects the intersections around the command point P _c , for example, four intersection points t _i ^{d + 1} , t _i ^d , t _i ^d−1 , t _i ^d− arranged on the machining path. Search for ² . The control device 50 creates a smooth curve (spline curve, Bezier curve, NURBS curve, etc.) from the four intersection points t _i ^{d + 1} , t _i ^d , t _i ^d-1 , t _i ^d-2 , The command point P _c is projected onto the image, and the correction point P _c ′ is determined. The control device 50 obtains a smooth curve by a method similar to the second correction method described above. The position of the correction point P _c ′ is a position where the distance from the command point P _c is minimum on a smooth curve. The control device 50 similarly corrects the positions of the other command points.

FIG. 16 is a flowchart for explaining the command point position correction process. CPU51 is above evaluation section setting process (step S3, see FIG. 5) at, after setting the rated cross-section D ^d, creating an intersection table (see FIGS. 11 and 12). Specifically, the CPU 51 sets “1” to the variable i indicating the path number of the reciprocating operation and the variable k indicating the order of the instructions constituting the machining program (step S41).

Then, the CPU 51 reads the movement route P _k -P _{k + 1} (step S42). The CPU 51 determines whether or not the travel route P _k −P _{k + 1} intersects with the evaluation section D ^d (step S43). When the movement route P _k -P _{k + 1} does not intersect the evaluation section D ^d (step S43: NO), the CPU 51 increments k by one (step S47).

When the movement path P _k -P _{k + 1} intersects with the evaluation section D ^d (step S43: YES), the CPU 51 has already reached the intersection S _i ^d between the evaluation section D ^d and the movement path P _k -P _{k + 1.} It is determined whether or not it exists (step S44).

When the intersection S _i ^d between the evaluation section D ^d and the movement route P _k −P _{k + 1} does not already exist (step S44: NO), the CPU 51 stores the route in the intersection table (see FIG. 12) in the storage unit 52. The number i, the intersection coordinates S _i ^d, and the movement route P _k -P _{k + 1} are stored in association with each other (step S46).

When the intersection S _i ^d between the evaluation section D ^d and the movement path P _k −P _{k + 1} already exists (step S44: YES), the CPU 51 increments i by one (step S45), and the CPU 51 stores the data. In the intersection table of the unit 52, the path number i, the intersection coordinates S _i ^d and the movement path P _k -P _{k + 1} are stored in association with each other (step S46), and k is incremented by one (step S47). Steps S41 to S47 constitute a calculation unit.

  After incrementing k, the CPU 51 determines whether k is the final number (step S48). If k is not the final number (step S48: NO), the CPU 51 returns the process to step S42. When k is the final number (step S48: YES), the CPU 51 corrects the position of the intersection as described above (see step S49, equations (1) to (4), FIGS. 13 and 14).

  As described above, the CPU 51 searches for intersections around the command point (step S50) and corrects the position of the command point (see step S51, FIG. 15A and FIG. 15B).

  In the above-described embodiment, the route A and the route B are located on the outermost periphery and the innermost periphery, but are not limited thereto. One of the route A or the route B may be positioned on the outer peripheral side, and the other may be positioned on the inner peripheral side.

In the control device 50 and the machine tool 100 according to the embodiment, the evaluation section D ^d is set so as to be perpendicular to the annular processing path, and the intersection S _i ^d of the evaluation section D ^d and the processing path is set. The position is corrected, and the position of the command point P _k in the direction intersecting the machining path is corrected based on the corrected position of the intersection S _i ^d .

When a plurality of evaluation sections D ^d are set so as to extend radially from the center of the processing path with respect to the annular processing path, a high density portion and a low density portion of the evaluation cross section D ^d are generated, and the command point P _The correction accuracy for _k may be reduced. In the embodiment described above, by making the evaluation section D ^d perpendicular to the machining path, even if a difference occurs in the density of the evaluation section D ^d , it is possible to prevent a reduction in correction accuracy with respect to the command point P _k . be able to.

In addition, the first reference point O _m and the second reference point L _m are set for the outer peripheral path and the inner peripheral path (path A and path B), respectively. The second reference point L _m is at a position closest to the first reference point O _m . As the first reference point O _m and the second reference point L _m is located on the evaluation section D ^d, by setting the evaluation section D ^d, evaluation section D ^d is substantially perpendicular to the machining path.

When the distance between the outer circumferential path and the inner circumferential path is small, the set evaluation section D ^d is inclined with respect to the machining path and intersects with another evaluation section D ^{d due} to a slight calculation error or the like. Sometimes. In the embodiment, the outer circumferential path is located on the outermost circumferential side and the inner circumferential path is located on the innermost circumferential side, so that there is sufficient space between the outer circumferential path and the inner circumferential path. It is possible to prevent the evaluation cross sections from intersecting each other by providing a large distance.

  One of the outer peripheral path and the inner peripheral path is located on the start point side of the machining path, and the other is located on the end point side of the machining path. When the starting point is located at the center of the spiral processing path, the outer peripheral path is positioned on the end point side, and the inner peripheral path is positioned on the starting point side. When the end point is located at the center of the machining path, the inner circumference side path is located on the end point side, and the outer circumference side path is located on the start point side.

5a Spindle 50 Controller 51 CPU
52 storage unit 53 RAM
100 machine tools

Claims (7)

In a control device that sets a machining path based on a plurality of command points that indicate the position of the spindle, and controls the movement of the spindle based on the machining path.
The processing path is annular,
An evaluation cross-section setting unit that sets an evaluation cross-section so as to be perpendicular to the machining path;
A calculation unit that calculates an intersection of the evaluation cross section set by the evaluation cross section setting unit and the machining path;
An intersection position correction unit for correcting the position of the intersection calculated by the calculation unit;
And a command point position correcting unit that corrects the position of the command point in a direction intersecting the machining path based on the intersection corrected by the intersection position correcting unit. The machining path is
An annular first path portion;
A second path portion having an annular shape located inside the first path portion,
The evaluation cross-section setting unit is
A first reference point setting unit for setting a first reference point on the first path unit;
A second reference point setting unit configured to set a second reference point at a position closest to the first reference point on the second path unit;
The control device according to claim 1, further comprising: an evaluation cross section calculating unit that calculates the evaluation cross section based on the first reference point and the second reference point. The machining path includes a plurality of path parts including the first path part and the second path part,
In the plurality of path portions, the first path portion is located on the outermost side,
The control device according to claim 2, wherein, in the plurality of path portions, the second path portion is located on the innermost side. The processing path has a spiral shape,
The plurality of command points include a start point command point located at the start point of the machining path and an end point command point located at the end point of the machining path,
A starting point side path part setting unit that sets one of the first path part or the second path part between the starting point command point and the first command point different from the starting point command point;
An end point side path part setting unit that sets the other of the first path part or the second path part between the end point command point and the second command point different from the end point command point, The control device according to claim 2 or 3. A control device according to any one of claims 1 to 4,
A machine tool comprising the spindle. In a control method for setting a machining path based on a plurality of command points that indicate the position of the spindle, and controlling the movement of the spindle based on the machining path,
The processing path is annular,
Set the evaluation cross section to be perpendicular to the machining path,
Calculate the intersection of the set evaluation cross section and the machining path,
Correct the calculated intersection point,
A control method comprising correcting a position of the command point in a direction intersecting the machining path based on the corrected intersection. According to a machining program, a computer program that can be executed by a control device that sets a machining path based on a plurality of command points that indicate the position of the spindle and controls the movement of the spindle based on the machining path,
The processing path is annular,
The control device;
An evaluation cross-section setting unit for setting an evaluation cross-section so as to be perpendicular to the machining path;
A calculation unit for calculating an intersection of the evaluation cross section set by the evaluation cross section setting unit and the machining path;
An intersection position correcting unit that corrects the position of the intersection calculated by the calculating unit, and a command point position that corrects the position of the command point in the direction intersecting the machining path based on the intersection corrected by the intersection position correcting unit A computer program that functions as a correction unit.

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