CN106625015A - Control device, machine tool and control method - Google Patents

Abstract

The present invention relates to a control device, a machine tool, and a control method for controlling the movement of a spindle of a mounting tool. The control device sets a plurality of command points for instructing the position of the main shaft, and sets interpolation points between the plurality of command points. The control device sets the processing path according to the instruction point and the interpolation point. When it is determined that the distance between two adjacent interpolation points, between a command point and an interpolation point, or between two interpolation points is not below the threshold, further set interpolation between two adjacent points point. The control device sets an evaluation section intersecting with the machining path, calculates the intersection point of the evaluation section and the machining section, and corrects the position of the intersection point. The control device corrects the positions of the instruction point and the interpolation point in the direction intersecting with the machining path according to the corrected intersection point, and forms a smooth curved surface on the workpiece.

Description

Control device, machine tool, control method

technical field

The present invention relates to a control device, a machine tool, and a control method for controlling the movement of a spindle of a mounting tool.

Background technique

The machine tool has a control device that controls the movement of the spindle on which the tool is mounted. The control device sets a plurality of command points indicating the position of the spindle, and connects the command points to set a machining path. When the tool mounted on the spindle forms a three-dimensional curved surface on the workpiece, the machining path is set by forming multiple curves with tiny line segments between consecutive command points.

For example, a plurality of curved lines are arranged in the front-back direction or the left-right direction on the horizontal plane. The control device sets a position in the vertical direction for each curve.

Japanese Laid-Open Patent Publication No. 3466111 discloses a control device. The control device adds auxiliary points (corresponding to "interpolation points" in this application) based on smooth curves such as spline curves and Bezier curves.

Even if each curve is smooth, a difference in slope of adjacent curves, a quantization error generated in the calculation of the control device, etc. will cause a scaly pattern to appear on the surface of the workpiece. The control device does not correct the command points, but inserts auxiliary points between the command points to generate a smooth curve. Even when the position of the command point is wrong, the curve passes through the wrong command point, and therefore, a scaly pattern appears on the surface of the workpiece.

Contents of the invention

The object of the present invention is to provide a control device, a machine tool and a control method capable of forming a smooth curved surface on a workpiece.

The control device of technical solution 1 sets a machining path based on a plurality of instruction points indicating the spindle position and at least one interpolation point set between the plurality of instruction points, and controls the movement of the spindle according to the machining path, so The control device includes a determination unit that determines whether the distance between two adjacent command points, between an adjacent command point and an interpolation point, or between two adjacent interpolation points is equal to or less than a threshold value. Judgment; interpolation point setting unit, when the judging unit judges that the distance is not below the threshold value, the interpolation point setting unit is between two adjacent instruction points, between adjacent instruction points and interpolation points, or between adjacent instruction points and interpolation points. The interpolation point is set between two adjacent interpolation points; the evaluation cross-section setting part is used to set the evaluation cross-section intersecting with the processing path; computing the intersection of the set evaluation section and the machining path; a first correction unit correcting the position of the intersection calculated by the calculation unit; and a second correction unit based on the first correction The position of the command point and the interpolation point in the direction intersecting the machining path is corrected using the partially corrected intersection point. Since the control device makes the distance between the command point and the interpolation point within the threshold and corrects the command point and the interpolation point based on the evaluation cross section, a smooth curve can be set.

The control device sets interpolation points between multiple command points, and sets the processing path according to the command points and the interpolation points. The control device sets the evaluation section, corrects the position of the intersection of the evaluation section and the machining path, and corrects the positions of the command point and the interpolation point in the direction intersecting the machining path according to the corrected intersection position.

The interpolation point setting unit of the control device according to claim 2 has a central setting unit, and the central setting unit is between two adjacent command points, between an adjacent command point and an interpolation point, or between two adjacent command points. Set the interpolation point at the center between the two interpolation points. The control device sets an interpolation point at the center between two adjacent instruction points, between an adjacent instruction point and an interpolation point, or between two adjacent interpolation points to set a machining path. Since the control device sets the interpolation point at the center of two adjacent points, it is possible to reduce the number of calculations for obtaining the interpolation point.

The interpolation point setting unit of the control device according to claim 3 includes a spaced position setting unit that sets the interpolation point at a position separated from the command point or the interpolation point by a threshold value. The control device sets an interpolation point at a position separated from the command point or the interpolation point by a distance equivalent to a threshold value, and sets the machining path. The control device sets interpolation points at positions separated by the threshold value, so the distance between two adjacent points becomes the threshold value, and a smooth curve can be set.

The control device according to claim 4 includes: a second determination unit that determines whether a second distance between the interpolation point corrected by the second correction unit and the second threshold value is equal to or less than a second threshold value. the distance between the interpolation points before being corrected by the second correction unit; and the interpolation point deletion unit, when the second determination unit judges that the second distance is equal to or less than a second threshold value, the interpolation point deletion unit selects 2. Delete the corrected interpolation points in the correction department. When the second distance between the two interpolation points before and after correction is smaller than the second threshold, the control device deletes the corrected interpolation point. By deleting interpolation points, the increase in machining time and machining program capacity is suppressed.

The control device according to claim 5 includes a third determination unit that determines whether a third distance between two adjacent distances corrected by the second correction unit is equal to or less than a third threshold value. The distance between the line segment connecting the instruction points and the interpolation point between the two adjacent instruction points corrected by the second correction unit and corrected by the second correction unit; and the second interpolation point The deletion unit deletes the interpolation point corrected by the second correction unit when the third determination unit determines that the third distance is equal to or less than the third threshold value. When the third distance between the corrected line segment connecting two adjacent command points and the corrected interpolation point between the two command points is smaller than the third threshold, the control device will Interpolation points are deleted. By deleting interpolation points, the increase in machining time and machining program capacity is suppressed.

A machine tool according to claim 6 includes the above-mentioned control device and spindle.

The control method of technical solution 7 sets a machining path based on a plurality of command points indicating the position of the main shaft and at least one interpolation point set between the plurality of command points, and controls the movement of the main shaft according to the machining path, the control The method judges whether the distance between two adjacent instruction points, between an adjacent instruction point and an interpolation point, or between two adjacent interpolation points is below a threshold. When it is below the threshold, set an interpolation point between two adjacent instruction points, between an adjacent instruction point and an interpolation point, or between two adjacent interpolation points, and set the Evaluate the section, calculate the intersection point between the set evaluation section and the processing path, correct the position of the calculated intersection point, and compare the positions of the command point and the interpolation point in the direction intersecting the processing path according to the corrected intersection point Make corrections.

Description of drawings

FIG. 1 is a perspective view showing a machine tool according to an embodiment.

FIG. 2 is a block diagram showing the configuration of a control device.

Fig. 3 is a plan view showing a machining path and an evaluation cross section of a workpiece.

Fig. 4 is a perspective view showing an evaluation cross section of a workpiece.

FIG. 5 is a flowchart illustrating machining route setting processing performed by the control device.

FIG. 6 is a schematic diagram schematically showing command points, interpolation points, and machining paths.

7 is a flowchart illustrating interpolation point setting processing performed according to the first interpolation method.

8 is a flowchart illustrating interpolation point setting processing performed according to the second interpolation method.

FIG. 9 is a schematic diagram showing intersection points of instruction points, interpolation points, evaluation cross sections, and machining paths.

FIG. 10 is a schematic diagram showing intersection points of instruction points, interpolation points, evaluation cross sections, and machining paths after assigning common identifiers to the instruction points and interpolation points.

FIG. 11 is a schematic diagram showing an example of an intersection table.

FIG. 12 is an explanatory diagram illustrating a first correction method for the intersection point position on the evaluation cross section.

FIG. 13 is an explanatory diagram for explaining a second correction method of the intersection point position on the evaluation cross section.

FIG. 14A is an explanatory diagram illustrating a method of correcting command points and interpolation points.

FIG. 14B is an explanatory diagram illustrating a method of correcting command points and interpolation points.

Fig. 15 is a flowchart illustrating command point/interpolation point correction processing performed by the control device.

FIG. 16 is an explanatory diagram illustrating a first method of deleting interpolation points.

FIG. 17 is a flowchart illustrating interpolation point deletion processing according to the first deletion method.

FIG. 18 is an explanatory diagram illustrating a second deletion method of interpolation points.

FIG. 19 is a flowchart illustrating interpolation point deletion processing according to the second deletion method.

FIG. 20 is a plan view showing a machining path and an evaluation cross section of a workpiece according to a modified example.

detailed description

A machine tool according to the embodiment will be described with reference to the drawings. In the following description, up and down, left and right, and front and rear indicated by arrows in the drawings are used. The machine tool 100 has a rectangular base 1 extending in the front-rear direction. The workpiece holding portion 3 is provided on the front side of the upper portion of the base 1 . The workpiece holding part 3 is rotatable around the A axis and the C axis. The axial direction of the A-axis is the left-right direction. The axial direction of the C-axis is the up-down direction.

A support table 2 for supporting a column 4 is provided on the rear side of the upper part of the base 1 . The Y-axis direction movement mechanism 10 is provided on the upper part of the support table 2, and moves the column 4 in the front-rear direction. The Y-axis direction moving mechanism 10 has two rails 11 extending in the front-rear direction, a Y-axis threaded shaft 12 , a Y-axis motor 13 and a bearing 14 .

The track 11 is located on the left and right sides of the support platform 2 top. The Y-axis threaded shaft 12 extends along the front-rear direction and is arranged between the two rails 11 . Bearings 14 are provided on the front end and the middle of the Y-axis threaded shaft 12 (not shown). The Y-axis motor 13 is connected to the rear end of the Y-axis threaded shaft 12 .

A nut (not shown) is screwed to the Y-axis threaded shaft 12 via a rotating body (not shown). The rotating body is, for example, a ball. A plurality of sliders 15 are slidably provided on each rail 11 . The moving plate 16 is connected with the nut and the upper part of the slider 15 . The moving plate 16 extends in the horizontal direction. The Y-axis threaded shaft 12 is rotated by the rotation of the Y-axis motor 13 , whereby the nut moves in the front-back direction, and the moving plate 16 moves in the front-back direction.

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

Rails 21 are provided on the front and rear sides of the upper surface of the movable plate 16 . The X-axis threaded shaft 22 extends left and right and is arranged between the two rails 21 . The bearing 24 is provided on the left end portion and the middle portion of the X-axis threaded shaft 22 (not shown). The X-axis motor 23 is connected to the rear end of the X-axis threaded shaft 22 .

A nut (not shown) is screwed to the X-axis threaded shaft 22 via a rotating body (not shown). A plurality of sliders 26 are slidably provided on each rail 21 . The column 4 is connected with the upper part of the nut and the slider 26 . The X-axis threaded shaft 22 is rotated by the rotation of the X-axis motor 23 , whereby the nut moves in the left-right direction and the column 4 moves in the front-back direction.

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

Rails 31 are provided on the left and right sides of the front surface of the column 4 . The Z-axis threaded shaft 32 extends vertically and is disposed between the two rails 31 . The bearing 34 is provided on the lower end portion and the middle portion of the Z-axis threaded shaft 32 (not shown). The Z-axis motor 33 is connected to the upper end of the Z-axis threaded shaft 32 .

A nut (not shown) is screwed to the Z-axis threaded shaft 32 via a rotating body (not shown). A plurality of sliders 35 are slidably provided on each rail 31 . The spindle head 5 is connected with the nut and the front part of the slider 35 . The Z-axis threaded shaft 32 is rotated by the rotation of the Z-axis motor 33 , whereby the nut moves up and down, and the spindle head 5 moves up and down. The Z-axis motor 33, the Z-axis threaded shaft 32, the nut and the rotating body constitute a ball screw mechanism.

A spindle 5 a extending in the vertical direction is provided in the spindle head 5 . The main shaft 5a rotates around the axis. The spindle motor 6 is provided on the upper end portion of the spindle head 5 . A tool is attached to the lower end of the spindle 5a. The spindle 5a is rotated by the rotation of the spindle motor 6, whereby the tool is rotated. The rotating tool processes the workpiece W (see FIG. 3 ) held by the workpiece holder 3 . The machine tool 100 has a tool changing device (not shown) for changing tools. The tool exchange device exchanges a tool stored in a tool magazine (not shown) with a tool attached to the spindle 5a.

As shown in FIG. 2 , the control device 50 has 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 EPROM, EEPROM, or the like. The storage unit 52 stores the following table of intersection points, route number i, interpolation point H _j , command point P _k , common identifier F _m , intersection point S _i ^d , final number of j, final number of k, threshold L, and threshold L2 (second threshold), threshold L3 (third threshold), the final number of m, variable S, etc. are stored (d, i, j, 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, for example, a keyboard, buttons, a touch panel, or the like. The input/output interface 54 outputs signals to the display unit 8 . The display unit 8 displays characters, graphics, symbols, and the like. The display unit 8 is, for example, a liquid crystal display.

The control device 50 has 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 has an encoder 23a. The X-axis control circuit 55 outputs a command indicating the amount of current to the servo amplifier 55 a in accordance with a command from the CPU 51 . The servo amplifier 55 a 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 23 a outputs a position feedback signal to the differentiator 23 b, and the differentiator 23 b 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 feedback control of the speed based on the speed feedback signal.

The current detector 55b detects the value of the drive current output by 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 performs current control according to the value of the drive current.

The control device 50 has a Y-axis control circuit 56 corresponding to the Y-axis motor 13, a servo amplifier 56a, a current detector 56b, and a differentiator 13b, and the Y-axis motor 13 has an encoder 13a. The Y-axis control circuit 56, the servo amplifier 56a, the differentiator 13b, the Y-axis motor 13, the encoder 13a, and the current detector 56b are the same as those of the X-axis, and description thereof will be omitted here.

The control device 50 has a Z-axis control circuit 57 corresponding to the Z-axis motor 33, a servo amplifier 57a, a current detector 57b, and a differentiator 33b. The Z-axis motor 33 has an encoder 33a. The Z-axis control circuit 57, servo amplifier 57a, differentiator 33b, Z-axis motor 33, encoder 33a, and current detector 57b are the same as those of the X-axis, and description thereof will be omitted here.

The control device 50 performs the same feedback control as that of the X-axis motor 23 on the spindle motor 6 . The machine tool 100 has a library motor 60 and a library control circuit 58 . The tool magazine is driven by the rotation of the magazine motor 60 . The library control circuit 58 controls the rotation of the library motor 60 .

The storage unit 52 stores a machining program for machining the workpiece W. As shown in FIG. The machining program has a plurality of command points _Pk indicating the position of the spindle 5a. k represents the order of commands constituting the machining program. The spindle 5a moves according to a plurality of command points _Pk , whereby the tool attached to the spindle 5a processes the workpiece W. As shown in FIG.

The storage unit 52 stores the instruction point P _k in advance. The control device 50 sets interpolation points among a plurality of command points P _k as necessary, and sets a path (machining path α) along which the spindle 5 a moves based on the command points P _k and the interpolation points. The control device 50 executes the movement of the spindle 5a according to the machining path α.

Next, the setting method of the machining path α will be described. The X direction in FIGS. 3 and 4 represents the left-right direction, the Y direction represents the front-rear direction, and the Z direction represents the up-down direction, and the shape of the workpiece W is the shape after processing.

The control device 50 sets an evaluation section D ^d (d represents a section number and is a natural number) for the workpiece W. When the main shaft 5a reciprocates along the X-axis direction, the machining path α is a path along the X-axis direction. The control device 50 sets a plurality of evaluation cross-sections D ^d along a direction substantially perpendicular to the machining path α. A plurality of evaluation cross sections are arranged along the X direction. In addition, the operator instructs the machining path α to be in the X direction in advance.

After the start signal is input, the control device 50 executes machining route setting processing. For example, the user operates the operation unit 7 to input a start signal to the control device. As shown in FIG. 5 , the CPU 51 executes interpolation point setting processing (step S1 ), command point/interpolation point correction processing (step S2 ), and interpolation point deletion processing (step S3 ). Details of interpolation point setting processing, command point/interpolation point correction processing, and interpolation point deletion processing will be described later.

Next, the interpolation point setting processing will be described. "i" (i is a natural number) in FIG. 6 shows the path number of the X direction movement of the main shaft 5a. As shown in Figure 6, for example, the path of path number 1 (i=1) represents a path from left to right, and the path of path number 2 (i=2) represents a path from right to right after turning back at the right end of path number 1. Path to move left. The same applies to route number 3 and onwards. The spindle 5a moves in the order of the path numbers. ●Indicates the instruction point, and the part with × in ○ indicates the interpolation point. Arrows indicate the advancing direction of the machining path α.

"j" (j is a natural number) represents the number of the interpolation point. When the distance D between two adjacent points (between two adjacent instruction values, between an adjacent instruction point and an interpolation point, or between two adjacent interpolation points) is greater than the threshold L, the CPU51 Set an interpolation point between two points. The CPU 51 sets the interpolation points by, for example, the first interpolation method.

Next, the interpolation point setting process performed by the first interpolation method will be described. As shown in FIG. 7, the CPU 51 sets 1 to j and k (step S11), and reads the command point _Pk and the command point _Pk+1 (step S12). The CPU 51 compares the distance D between the command point P _k and the command point P _k+1 with the threshold L, and determines whether the distance D is equal to or less than the threshold L (step S13 ).

When the distance D is equal to or less than the threshold value L (step S13: Yes), the CPU 51 advances the process to step S18 described later. When the distance D is not equal to or less than the threshold value L (step S13: No), the CPU 51 sets an interpolation point _Hj at the center between two adjacent points (step S14). The two adjacent points are two command points P _k and P _k+1 . However, after one or more interpolation points are set, the adjacent two points may be the adjacent instruction point and the interpolation point, or may be the adjacent two interpolation points.

The CPU 51 stores the position information of the interpolation point H _j in the storage unit 52 in association with the position information of the instruction points P _k and P _k+1 (step S15 ). The CPU 51 judges whether all the distances between two adjacent points are equal to or less than the threshold value L (step S16). All the distances between two adjacent points are the distance between the command point P _k and the interpolation point H _j and the distance between the interpolation point H _j and the command point P _k+1 . However, after setting a plurality of interpolation points, the adjacent command point and interpolation point or two adjacent command points are also included in all the adjacent two points.

When not all the distances between adjacent two points are equal to or less than the threshold value L (step S16: NO), the CPU 51 adds 1 to j (step S17), and returns the process to step S14. When the distances between all the adjacent two points are below the threshold L (step S16: Yes), the CPU 51 determines whether the command point _Pk+1 is the final command point (step S18). For example, the CPU 51 determines whether k is greater than or equal to the final number stored in the storage unit 52. When k is greater than the final number, it is determined that the command point P _k+1 is the final command point. When k is not greater than the final number, it is determined that it is the command point. P _k+1 is not the final instruction point.

When the instruction point P _k+1 is not the final instruction point (step S18: NO), the CPU 51 adds 1 to k (step S19), and returns the process to step S12. When the instruction point _Pk+1 is the final instruction point (step S18: YES), the CPU 51 returns the process to the instruction point/interpolation point processing (step S2, see FIG. 5). Step S13 constitutes a determination unit, steps S14 to S17 constitute an interpolation point setting unit, and step S14 constitutes a central setting unit.

Using the route number 5 (i=5) of the machining route α shown in FIG. 6 , an example of the interpolation point setting process performed by the above-mentioned first interpolation method will be described. _The distance between the command point _P15 and the command point P16 exceeds the threshold L. As the number of the interpolation point _Hj , the number indicated above the route number 5 is used. The interpolation points H _j in parentheses are interpolation points when the second interpolation method described later is used.

The CPU 51 sets an interpolation point H ₄ at the center between the command point P ₁₅ and the command point P ₁₆ . _The distance between the instruction point _P15 and the instruction point H4, and the distance between the instruction point _H4 and the instruction point _P16 exceed the threshold L. The CPU 51 sets an interpolation point H ₅ at the center between the command point P ₁₅ and the interpolation point H ₄ . _The distance between the instruction point _P15 and the instruction point _H5 , and the distance between the two interpolation points H4, _H5 exceed the threshold L. The CPU 51 sets an interpolation point H ₆ at the center between the command point P ₁₅ and the interpolation point H ₅ . The distance between the command point _P15 and the command point _H6 , and the distance between the two interpolation points _H6 and _H5 are equal to or smaller than the threshold value L. The CPU 51 sets an interpolation point H ₇ at the center between the two interpolation points H ₅ and H ₄ . The distance between the two interpolation points H ₅ and H ₇ and the distance between the two interpolation points H ₇ and H ₄ are equal to or less than the threshold L. Similarly, the CPU 51 sets interpolation points H ₈ , H ₉ , and H ₁₀ between the interpolation point H ₄ and the command point P ₁₆ . Distance between two interpolation points H ₄ , H ₉ , distance between two interpolation points H ₉ , H ₈ , distance between two interpolation points H ₈ , H ₁₀ , interpolation point H _{10 The} distance from the command point P16 is equal to or less than the threshold L.

The CPU 51 sets interpolation points using, for example, the second interpolation method. As shown in FIG. 8 , the CPU 51 sets 1 to j and k (step S21 ), and reads the instruction point P _k and the instruction point P _k+1 (step S22 ). The CPU 51 compares the distance D between the command point P _k and the command point P _k+1 with the threshold L, and determines whether the distance D is equal to or less than the threshold L (step S23 ). When the distance D is equal to or less than the threshold value L (step S23: Yes), the CPU 51 advances the process to step S29 described later. When the distance D is not equal to or less than the threshold value L (step S23: NO), the CPU 51 stores the positional information of the instruction point _Pk in the variable S (step S24). The CPU 51 sets the interpolation point H _j at a position separated by the threshold value L from the position stored in the variable S toward the command point P _k+1 (step S25 ). The CPU 51 stores the position information of the interpolation point H _j in the storage unit 52 in association with the position information of the instruction points P _k and P _k+1 (step S26 ).

The CPU 51 determines whether or not the distance between the interpolation point _Hj and the command point _Pk+1 is equal to or less than a threshold (step S27). When the distance between the interpolation point H _j and the command point P _k+1 is not below the threshold (step S27: No), the CPU 51 adds 1 to j, and stores the position information of the interpolation point H _j in the variable S (step S28) , and returns the process to step S25.

When the distance between the interpolation point _Hj and the command point _Pk+1 is equal to or less than the threshold value L (step S27: Yes), the CPU 51 determines whether the command point _Pk+1 is the final command point (step S29). When the command point P _k+1 is not the final command point (step S29: NO), the CPU 51 adds 1 to k (step S30), and returns the process to step S22. When the command point P _k+1 is the final command point (step S29: YES), the CPU 51 advances the process to the command point/interpolation point correction process (step S2, see FIG. 5). The CPU 51 executing step S23 constitutes a determination unit, the CPU 51 executing steps S24 to S28 constitutes an interpolation point setting portion, and the CPU 51 executing step S25 constitutes a separation position setting portion.

Next, an example of the interpolation point setting process performed by the above-mentioned second interpolation method will be described using the route number 5 (i=5) of the machining route α shown in FIG. 6 . _The distance between the command point _P15 and the command point P16 exceeds the threshold L. The number of the interpolation point H _j uses the number shown in parentheses.

The CPU 51 sets an interpolation point (H ₄ ) at a position separated by the threshold value L from the command point _P15 to the command point _P16 side. The distance between the interpolation point (H ₄ ) and the instruction point P ₁₆ exceeds the threshold L. The CPU 51 sets the interpolation point (H ₅ ) at a position separated by the threshold value L from the interpolation point (H ₄ ) toward the command point P ₁₆ side. The distance between the interpolation point (H ₅ ) and the instruction point P ₁₆ exceeds the threshold L. Similarly, the CPU 51 sets a distance of the threshold value L _at a position closer to the command point P16 than the interpolation point (H ₅ ), and sequentially sets the interpolation point (H ₆ ) to the interpolation point (H ₁₀ ). The distance between the interpolation point (H ₁₀ ) and the command point P ₁₆ is equal to or less than the threshold L.

Next, the command point/interpolation point correction processing will be described. Fig. 9 shows command point P _k , interpolation point H _j , intersection _{S i} ^d of evaluation section D ^d and machining path α, and Fig. 10 shows the allocation of common identifier F _m ( _m is a natural number), the command point, the interpolation point, the intersection point S _i ^d of the evaluation section D ^d and the machining path α. The CPU 51 assigns an identifier F _m to the instruction point and the interpolation point. The CPU 51 stores the identifier F _m in the storage unit 52 in association with the command point P _k and the interpolation point H _j .

As shown in FIG. 11 , the control device 50 calculates the intersection point S _i ^d of each evaluation section D ^d and the moving path F _m −F _m+1 , and calculates the path number i, the coordinate value of the intersection point S _i ^d , and the moving path F _m - F _m+1 are correspondingly stored in the intersection table. As described above, i (i is a natural number) represents the path number of the X-direction movement of the spindle 5a. The control device 50 constitutes a computing unit.

As shown in FIG. 12 , the control device 50 corrects the position of the intersection point on the evaluation section ^Dd , for example, using the first correction method. The control device 50 performs correction by gradually changing the coordinate value in the Z direction. For the coordinate value of the intersection point S _i ^d of the correction object, use the coordinate values of the two intersection points s _i-2 ^d , s _i-1 ^d , s _i+1 ^d , and s _i+2 ^d to determine the correction point t _id .

Set the Z coordinate values of the four intersection points s _i-2 ^d , s _i-1 ^d , s _i+1 ^d , s _i+2 ^d to 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 set to z _i ', the difference of the Z coordinate value is d _(i-2,i-1) = z _i-2 -z _i-1 , d _{(i -1,i)} =z _i-1 -z _i ', d _(i,i+1) =z _i '-z _i+1 , d _4(i+1,i+2) =z _i+1 - z _i+2 , the secondary difference d ₁₂ ′, d ₂₃ ′, d ₃₄ ′ of the control device 50 to the Z coordinate value (difference of the Z coordinate d _(i-2,i-1) , d _{(i-1,i )} , d _(i,i+1) , d _4(i+1,i+2) difference) z _i ' which changes linearly is operated.

The second difference d ₁₂ ′, d ₂₃ ′, and d ₃₄ ′ of the Z coordinate value are obtained by the following formula.

d ₁₂ '=d _(i-1,i) -d _(i-2,i-1) =(z _i-1 -z _i ')-(z _i-2 -z _i-1 )=2z _{i- 1} -z _i '-z _i-2 ... (1)

d ₂₃ '＝d _(i,i+1) -d _(i-1,i) ＝(z _i '-z _i+1 )-(z _i-1 -z _i ')＝2z _i '-z _{i +1} -z _i-1 ... (2)

d ₃₄ '＝d _4(i+1,i+2) -d _(i,i+1) ＝(z _i+1 -z _i+2 )-(z _i '-z _i+1 )＝2z _{i +1} -z _i+2 -z _i '...(3)

Since these d ₁₂ ′, d ₂₃ ′, and d ₃₄ ′ change linearly, the following formula is satisfied.

d ₂₃ '=(d ₁₂ '+d ₃₄ ')/2...(4)

If z _i ' is solved according to formula (1) to formula (4), the following formula can be obtained.

z _i '＝(-z _i-2 +4z _i-1 +4z _i+1 -z _i+2 )/6

The above-mentioned correction is performed for all intersection points S _i ^d on the evaluation section D ^d . It is also possible to correct only the intersection points whose Z coordinates are far away from the Z coordinate values of other intersection points.

As shown in FIG. 13 , the control device 50 corrects the position of the intersection point on the evaluation section ^Dd , for example, by the second correction method. In FIG. 13, u corresponds to XY coordinates, and v corresponds to Z coordinates. The control device 50 generates a smooth curve (spline curve, Bezier curve, ^NURBS curve, etc.) using other plural intersection points located around the intersection point S _id of the correction object, and projects the intersection point S _id of the correction ^object onto the curve superior.

When four intersection points s _i-2 ^d , s _i-1 ^d , s _i+1 ^d , and s _i+2 ^d are used as smooth curves, the section s _i-2 ^d on the cross-section D ^d (uv plane) is evaluated Each curve formula v ₁ (u), v ₂ (u), v ₃ of ~s _i-1 ^d , interval s _i-1 ^d ~s _i+1 ^d , interval s _i+1 ^d ~s _i+2 ^d (u) is represented by the following formula.

v _j (u)＝a _j (uu _j ) ³ +b _j (uu _j ) ² +c _j (uu _j )+d _j

(j=1, 2, 3)

According to v _j (u) passing through the intersection points s _i-2 ^d , s _i-1 ^d , s _i+1 ^d , s _i+2 ^d and the first and second derivatives at the intersection points are continuous, the control device 50 can Determine a _j to d _j . The selection of the four intersection points is not limited to the above-mentioned two consecutive points located adjacent to both sides of the intersection point S _i ^d . For example, discontinuous intersection points may be selected in units of two points such as the intersection points s _i-3 ^d , s _i-1 ^d , s _i+1 ^d , and s _i+3 ^d . As shown in FIG. 13 , the position of the correction point t _i ^d is the position on the smooth curve at which the distance from the intersection point S _i ^d to be corrected is the shortest.

Let the corrected intersection point group S ^d existing on the d-th evaluation section D ^d be T _d .

T ^d ＝{t _i ^d |d: section number, i: path number}

As shown in FIGS. 14A and 14B , the control device 50 corrects the positions of the command point and the interpolation point using the intersection point group ^Td . In FIGS. 14A and 14B , F _a to F _f represent instruction points or interpolation points. For example, when the command point or interpolation point F _c is the correction target, as shown in FIG. 14A , the command point or interpolation point F _c is located between section ^Dd-1 and section ^Dd , and the path number is i. The control device 50 refers to the above-mentioned intersection table, and acquires the cross-sectional position and the path number related to the command point or the interpolation point _Fc .

As shown in FIG. 14B , the control device 50 controls the intersection points around the command point or the interpolation point Fc, for example, the four intersection points t _{i d} ⁺¹ , t _i ^d , t _i ^d-1 , t _i ^d-2 to search. The control device 50 generates a smooth curve (spline curve, Bezier curve, NURBS curve, etc.) from four intersection points t _i ^d+1 , t _i ^d , t _i ^d-1 , t _i ^d-2 , Or project the interpolation point F _c onto the curve, and determine the correction point F _c '. The control device 50 obtains a smooth curve by the same method as the above-mentioned second correction method. The position of the correction point _Fc ' is the position on the smooth curve at which the distance from the command point or the interpolation point _Fc is the shortest. The control device 50 similarly corrects the positions of other command points or interpolation points.

Next, the command point/interpolation point correction processing performed by the control device 50 will be described. As shown in Figure 15, _CPU51 sets evaluation section D ^d (step _S41 ), and assigns common identifier F _m (m is a natural number) (step S42, referring to Fig. 9 and Fig. 10). The CPU 51 creates an intersection table (see FIG. 11 ). . Specifically, the CPU 51 sets "1" to the variable i and the variable m indicating the route number of the reciprocating operation (step S43). The variable m indicates the sequence of commands constituting the machining program. The CPU 51 reads the moving route F _m -F _m+1 (step S44). The CPU 51 determines whether or not the movement route F _m -F _m+1 intersects the evaluation section D ^d (step S45 ). When the movement path F _m -F _m+1 does not intersect the evaluation section D ^d (step S45: No), the CPU 51 adds 1 to m (step S49). Step S41 constitutes an evaluation section setting unit.

When the moving path Fm-Fm ₊₁ intersects with the evaluation section ^Dd (step S45: yes), the CPU 51 determines whether the intersection S _{i d} of the evaluation section ^Dd and the moving path Fm- ^Fm _{+1 already} exists ( Step S46). When the intersection point S _i ^d of the evaluation section D ^d and the moving path F _m -F _m+1 does not exist yet (step S46: No), the CPU 51 sets the path number i, the coordinate value of the intersection point S _i ^d , the moving path F _m -F _{m +1} is correspondingly stored in the intersection table (see FIG. 11 ) of the storage unit 52 (step S48).

When the intersection S _i ^d of the evaluation section D ^d and the moving path F _m -F _m+1 already exists (step S46: yes), the CPU51 adds 1 to i (step S47), and the CPU51 sets the path number i, the intersection S _i ^d The coordinate values and the moving route F _m -F _m+1 are associated and stored in the intersection table of the storage unit 52 (step S48 ), and 1 is added to m (step S49 ). Steps S43 to S49 constitute a calculation section.

After adding 1 to m, the CPU 51 judges whether or not m is the final number (step S50). When m is not the final number (step S50: NO), the CPU 51 returns the process to step S44. m is the final number (step S50: Yes), and the CPU 51 corrects the position of the intersection point as described above (step S51, formula (1) to formula (4), refer to FIG. 12 and FIG. 13 ). CPU51 searches for the intersection point around the instruction point as described above (step S52), corrects the position of the instruction point or the interpolation point (step S53, referring to FIG. 14A, FIG. 14B), and makes the process advance to the interpolation point deletion process (Step S3, refer to FIG. 5). Step S51 constitutes a first correcting unit, and step S53 constitutes a second correcting unit.

Next, the interpolation point deletion processing will be described. As shown in FIG. 16 , the control device 50 deletes the interpolation points by, for example, the first deletion method. In FIG. 16 , the command points before correction by the command point/interpolation point correction process are P _k , P _k+1 , and the command points after correction are P _k ′, P _k+1 ′. The interpolation points before correction by command point/interpolation point correction processing are H _j , H _j+1 , and the interpolation points after correction are H _j ′, H _j+1 ′. The CPU 51 stores the common identifier F _m , the corrected command point, and the interpolation point in association with each other in the storage unit 52 .

The control device judges whether the distance D2 (second distance) between the interpolation point _Hj before correction and the interpolation point _Hj ' after correction is less than or equal to a threshold value L2 (second threshold value), and the distance D2 is less than or equal to the threshold value L2 , delete the corrected interpolation point H _j '. When the distance D2 is equal to or smaller than the threshold value L2, the difference between the interpolation point H _j before correction and the interpolation point H _j ′ after correction is small. Therefore, even if the interpolation point H _j ' is deleted and the spindle 5a is directly moved from the command point P _k ' to the interpolation point H _j+1 ', the influence on the surface shape of the workpiece is small, and scales appear on the surface of the workpiece. Patterns are less likely. Since interpolation points are deleted, it is possible to suppress increases in machining time and machining program capacity. When all the corrected interpolation points are deleted, the spindle 5a directly moves from the command point P _k ' to the command point P _k+1 '.

Next, the interpolation point setting process performed by the first deletion method will be described. As shown in FIG. 17, the CPU 51 sets 1 to j (step S61), and reads the interpolation point _Hj before correction and the interpolation point _Hj ' after correction (step S62). The CPU 51 determines whether or not the distance D2 between the interpolation points _Hj and _Hj ' is equal to or less than a threshold value L2 (step S63). When distance D2 is not below threshold value L2 (step S63: NO), CPU51 advances a process to step S65 mentioned later. Step S63 constitutes a second determination unit.

When the distance D2 is equal to or less than the threshold L2 (step S63: Yes), the CPU 51 deletes the interpolation point H _j ' (step S64), and determines whether the interpolation point H _j ' is the final interpolation point (step S65). For example, the CPU 51 judges whether or not j is greater than or equal to the final number stored in the storage unit 52. When j is greater than the final number, it is determined that the interpolation point H _j ' is the final interpolation point. When j is not greater than the final number, it is determined that it is an interpolation point. The interpolation point H _j ' is not the final interpolation point. Step S64 constitutes an interpolation point deletion unit.

When the interpolation point _Hj ' is not the final interpolation point (step S65: NO), the CPU 51 adds 1 to j (step S66), and returns the process to step S62. When the interpolation point _Hj ' is the final interpolation point (step S65: YES), the CPU 51 ends the processing.

The control device 50 deletes the interpolation points by, for example, the second deletion method. The command points before correction by the command point/interpolation point correction process are P _k , P _k+1 , and the interpolation points before correction by the command point/interpolation point correction process are H _j , H _j+1 . As shown in Figure 18, the designated points corrected by the command point/interpolation point correction process are P _k ', P _k+1 ', and the interpolation point corrected by the command point/interpolation point correction process is H _j ', H _j+1 '. The CPU 51 stores the common identifier F _m , the corrected command point, and the interpolation point in association with each other in the storage unit 52 .

The control device checks whether the distance D3 (third distance) between the line segment connecting the corrected command points _Pk ' and _Pk+1 ' and the corrected interpolation point _Hj ' is less than or equal to the threshold L3 (third threshold) When it is judged that the distance D3 is equal to or less than the threshold value L3, the corrected interpolation point H _j ′ is deleted. The distance D3 is, for example, the shortest distance between the line segment and the corrected interpolation point H _j ′.

When the distance D3 is equal to or less than the threshold value L3, the difference between the interpolation point H _j before correction and the interpolation point H _j ′ after correction is small. Therefore, even if the interpolation point H _j ' is deleted and the spindle 5a is directly moved from the command point P _k ' to the interpolation point H _j+1 ', the influence on the surface shape of the workpiece is small, and scales appear on the surface of the workpiece. Patterns are less likely. Since interpolation points are deleted, it is possible to suppress increases in machining time and machining program capacity. When all the corrected interpolation points are deleted, the spindle 5a directly moves from the command point P _k ' to the command point P _k+1 '.

The interpolation point deletion processing according to the second deletion method will be described below. As shown in Figure 19, CPU51 sets 1 to j, k (step S71), reads in the corrected command point P _k ', P _k+1 ' (step S72), and sets the line segment P _k 'P _{k+ 1} ' (step S73).

The CPU 51 reads the corrected interpolation point H _j ' (step S74), and determines whether the distance D3 between the line segment P _k 'P _k+1 ' and the interpolation point H _j ' is below the threshold L3 (step S75 ). When the distance D3 is not less than the threshold L3 (step S75: No), the CPU 51 determines whether the interpolation point H _j ' in the machining route P _k '-P _k+1 ' is the final interpolation point (step S77). The storage unit 52 stores the final number of j for each machining pass. Step S75 constitutes a third determination unit.

When the distance D3 is not below the threshold L3 (step S75: yes), the CPU 51 deletes the interpolation point H _j ' (step S76), and checks whether the interpolation point H _j ' is the final value in the processing path P _k '-P _k+1 ' The interpolation point is judged (step S77). When the interpolation point _Hj ' in the machining path Pk'- _{Pk +1} ' is not the final interpolation point (step S77: NO), the CPU 51 adds 1 to j (step S78), and returns the process to step S74. Step S76 constitutes a second interpolation point deletion unit.

When the interpolation point H _j ' in the machining path P _k '-P _k+1 ' is the final interpolation point (step S77: yes), CPU51 judges whether the command point P _k+1 ' is the final command point (step S79 ). When the instruction point P _k+1 ' is not the final instruction point (step S79: NO), the CPU 51 adds 1 to k (step S80), and returns the process to step S72. When the command point _Pk+1 is the final command point (step S79: YES), the CPU 51 ends the processing.

In the embodiment, the interpolation point H _j is set between a plurality of command points P _k , and the machining route α is set based on the command point P _k and the interpolation point H _j . Set the evaluation section D ^d intersecting the processing path α _, correct the position of the intersection S _i ^d of the evaluation section ^{D d} and the processing path Correct the positions of command point P _k and interpolation point H _j in the direction. By correcting the positions of the command point P _k and the interpolation point H _j in the direction intersecting the machining path α, a smooth curved surface can be formed on the workpiece. Not only the instruction points but also the interpolation points _Hj set between the instruction points _Pk are used for setting the machining path α, so that the accuracy of the machining path α can be improved.

The machining path α is set by setting an interpolation point between two adjacent instruction points, between an adjacent instruction point and an interpolation point, or between two adjacent interpolation points. Alternatively, the machining path α is set by setting an interpolation point at a position separated from the command point or the interpolation point by a distance corresponding to the threshold L.

When the distance D2 (second distance) between two interpolation points before and after correction is smaller than the threshold L2 (second threshold), the corrected interpolation point is deleted. Alternatively, the distance D3 (third distance) between the line segment connecting the corrected two adjacent command points and the corrected interpolation point located between the two command points is smaller than the threshold L3 (third distance). threshold), delete the corrected interpolation points. By deleting interpolation points, the increase in machining time and machining program capacity is suppressed.

In the above-described embodiment, all the processing of interpolation point setting processing, command point/interpolation point correction processing, and interpolation point deletion processing is executed, but only interpolation point setting processing, command point/interpolation point Compensation point correction processing.

An example in which a partial change is made to the structure is described below. As shown in FIG. 20 , when the machining path β is in a spiral shape, the control device 50 sets the center of the spiral and the angle developed around the center, and radially sets a plurality of evaluation sections based on the center of the spiral.

Claims (7)

1. A control device (50), which sets a processing path according to a plurality of instruction points indicating the position of the main shaft (5a) and at least one interpolation point set between the plurality of instruction points, and according to the processing path Controlling the movement of the main shaft, characterized in that it has: A determination unit that determines whether the distance between two adjacent instruction points, between an adjacent instruction point and an interpolation point, or between two adjacent interpolation points is equal to or less than a threshold ; an interpolation point setting unit that, when the determination unit determines that the distance is not equal to or less than the threshold value, sets the interpolation point setting unit between two adjacent command points, the adjacent command The interpolation point is set between a point and an interpolation point or between two adjacent interpolation points; an evaluation cross-section setting unit that sets an evaluation cross-section intersecting the machining path; a calculation unit that calculates the intersection of the evaluation cross-section set by the evaluation cross-section and the machining path; a first correction unit that corrects the position of the intersection calculated by the calculation unit; and a second correcting unit that corrects the positions of the command point and the interpolation point in a direction intersecting the machining path based on the intersection point corrected by the first correcting unit. 2. The control device according to claim 1, wherein the interpolation point setting unit has a central setting unit, and the central setting unit is between two adjacent command points and adjacent to each other. The interpolation point is set at the center between the instruction point and the interpolation point or between two adjacent interpolation points. 3. The control device according to claim 1, wherein the interpolation point setting unit has a spaced position setting unit, and the spaced position setting unit is spaced apart from the command point or the interpolation point. Set the interpolation point at the position where the threshold is opened. 4. The control device according to any one of claims 1 to 3, characterized in that it has: A second judging unit that judges whether a second distance between the interpolation point corrected by the second correcting unit and the interpolation point corrected by the second correcting unit is equal to or less than a second threshold value. the distance between said interpolation points before partial correction; and The interpolation point deletion unit deletes the interpolation point corrected by the second correction unit when the second determination unit determines that the second distance is equal to or smaller than the second threshold value. 5. The control device according to any one of claims 1 to 3, characterized in that it has: A third judging unit, the third judging unit judging whether a third distance is below a third threshold value, the third distance refers to connecting two adjacent command points corrected by the second correcting unit The distance between the line segment of and the interpolation point corrected by the second correction unit between two adjacent instruction points; and The second interpolation point deletion unit is configured to delete the interpolation point corrected by the second correction unit when the third determination unit determines that the third distance is equal to or less than a third threshold value. delete. 6. A machine tool (100), characterized in that it has: A control device as claimed in any one of claims 1 to 5; and the spindle. 7. A control method, setting a processing path according to a plurality of instruction points indicating the position of the main shaft (5a) and at least one interpolation point set between the plurality of instruction points, and setting the processing path according to the processing path The movement of the spindle is controlled, characterized in that, Determine whether the distance between two adjacent instruction points, between an adjacent instruction point and an interpolation point, or between two adjacent interpolation points is below a threshold; When it is determined that the distance is less than or equal to the threshold value, an interpolation point is set between two adjacent instruction points, between an adjacent instruction point and an interpolation point, or between two adjacent interpolation points. Determine the interpolation point; setting an evaluation section intersecting with the processing path; calculating the intersection of the set evaluation section and the machining path; Correct the position of the computed intersection point; The positions of the command point and the interpolation point in a direction intersecting with the machining path are corrected according to the corrected intersection point.