WO2002077729A1

WO2002077729A1 - Multispindle finishing machine and its motor control method

Info

Publication number: WO2002077729A1
Application number: PCT/JP2001/002493
Authority: WO
Inventors: Tomoaki Hachiya; Hirochika Takahashi; Masashi Nakayama; Yuuichi Komazawa; Kiyoshi Natsume; Eiji Obayashi
Original assignee: Technowave, Inc.; Asahi-Seiki Manufacturing Co., Ltd.
Priority date: 2001-03-27
Filing date: 2001-03-27
Publication date: 2002-10-03
Also published as: JPWO2002077729A1

Abstract

A method and a software program for controlling the motor of a multispindle finishing machine where a work is machined by means of a tool fixed to each spindle by driving motors provided to the respective spindles sequentially such that each spindle arrives at a target position sequentially characterized in that a pre-interpolation acceleration/deceleration system receiving at least a data sequence of position among data sequences of position, speed and acceleration and outputting speed-continuous interpolation data is employed and the net step is actuated by shifting the target position of each step toward the start position of that step thereby overlapping a specified travel distance for each step during the operation of the step.

Description

Description Multi-axis machine and control method of its motor

Technical field

The present invention relates to a multi-axis machine capable of reducing tact time, a motor control method thereof, and a motor control software. Background art

In a general control method of a multi-axis processing machine such as a panel molding machine, the operation of a plurality of servo motors provided for each axis is independently processed for each step, and each axis is moved from a step start position to a target position. From the beginning to the end — a method of creating intercept data that moves at a constant speed.

In this case, if the command speed changes between steps, or if the direction angle changes while interpolating so that they arrive at the same time, the speed of each axis changes discontinuously, and if it is output as a command to the motor as it is, , A large shock occurs. Therefore, acceleration / deceleration processing is required to operate smoothly. As a method of acceleration / deceleration, a filter method is generally used.

This is because a FIFO buffer of a certain length is prepared, the data obtained by interpolating the trajectory is recorded in the buffer while receiving it every moment, and the data in the buffer is averaged. This is a method of controlling the motor as the data of.

However, this method has a disadvantage that when the speed is changed, the trajectory changes significantly. For example, it is slow to check the operation of a newly created software program. When operating at high speed during actual operation, the operation is not reproducible, the adjustment depends on intuition, and as a result, unnecessary setup time is required, and the final product shape is also low precision.

In order to prevent the trajectory from changing even if the speed is changed, a function called an inert stop check mode or an in-position check mode is used. This is a function that starts the operation of the next step after confirming at each step whether the axis has completely stopped or the servo deviation of the axis has become sufficiently small. This would not be affected by the acceleration and deceleration of the filter system, and the trajectory would not change with speed, but the tact time would be unnecessarily long, which would be a problem in terms of productivity.

If you do not want to increase the tact time, you must create a machining program without in-position checking as much as possible.

However, as described above, not only the trajectory becomes inaccurate as described above, but also the trajectory changes with each speed change, and it becomes difficult to verify the machining program before actual operation.

As a result, wasted time is required for setup, and the accuracy of the final product shape cannot be improved. DISCLOSURE OF THE INVENTION Therefore, by using acceleration / deceleration before capture instead of the filter method, the trajectory change for each speed change is reduced, and at the same time, the target position is intentionally shifted to the front when performing calculations, as if It suffices if the operation of the step can be realized so as to overlap the original step.

For this purpose, the acceleration / deceleration method before catching includes at least It is sufficient if a method can be used that takes a data sequence of position, speed, and acceleration as input, automatically calculates necessary data, and outputs interpolation data with continuous speed.

As a result, the tact time can be reduced, and the reproducibility of the trajectory including how much overlap is maintained.

The present invention has been made based on the above-mentioned viewpoints, and the object is to prepare interception data such as continuous speed, given a speed and a target position of each axis for each step, At the same time, the present invention provides a motor control method for a multi-axis machine capable of reducing tact time by allowing overlap between steps. In order to achieve the above-mentioned object, the invention described in claim 1 is to sequentially drive a motor provided on each axis so that each axis sequentially reaches a target position, and a tool mounted on each axis is used for a workpiece. A method of controlling a motor in a multi-axis machine that performs machining, in which at least a position data sequence of a position, speed and acceleration data sequence is input and interpolation data for continuous speed is output. By adopting the acceleration / deceleration method before interpolation and shifting the target position of each step to the side closer to the start position of the step, each step is overlapped by a predetermined moving distance during the operation of the step, and the next step Is activated.

The term “acceleration / deceleration before interpolation” used in the present invention refers to a stage in which data obtained by interpolating a trajectory is input with a data sequence of position, speed, and acceleration including at least a position, and necessary data is automatically calculated. In addition, it is a method that outputs interception data with continuous speed.

In this method, when the time elapsed from the start point or the time is input, it is output. A calculation method that can be defined as a function that can obtain a target position as a force can also be used. As a result, since the input to the function for calculating the target position can be performed instead of the actual elapsed time itself, even if the virtual internal time subjected to the acceleration / deceleration processing is changed, the trajectory accuracy does not decrease.

This means that by using the filter method for accelerating and decelerating the internal time, the advantage of the one-sided finoleta system can also be obtained.

In addition, the tact time can be reduced by overlapping each step. The invention described in claim 2 employs a trapezoidal speed trapping method as the pre-trapping acceleration / deceleration method.

The term “trapezoidal velocity trap” as defined in the present invention means that the current position and the current velocity are known, a series of the target position and the target velocity are given, and the acceleration of each axis is specified. In this method, the speed change up to each target position in the sequence is sequentially determined as a piecewise linear function so that the speed is continuous.

Therefore, in this method, the relationship between the moving time and the moving distance for each step can be derived only by applying the trapezoidal area formula, which simplifies the method and reduces the calculation load. The invention described in claim 3 is characterized in that, before calculating the trapezoidal velocity capture at each step, the target position is changed so that the moving distance becomes smaller at a fixed rate. 2 is a method for controlling a motor in the multi-axis machine described in 2.

Normally, how small the moving distance is specified by a parameter. According to the invention described in claim 4, the ratio of decreasing the moving distance is calculated by using both the parameter indicating the absolute moving distance and the parameter indicating the ratio to the original moving distance, and the smaller one is used. 4. The method for controlling a motor in a multi-axis machine according to claim 3, wherein the value is selected. The invention described in claim 5 is a multi-axis machining apparatus that sequentially drives a motor provided on each axis so that each axis sequentially reaches a target position and processes a workpiece with a tool attached to each axis. Pre-interval acceleration / deceleration method, which is software for motor control of a processing machine, which receives at least the position data sequence of the position, speed, and acceleration data sequences and outputs interpolated data with continuous speed. And by shifting the target position of each step to the side closer to the start position of the step, it is possible to overlap the predetermined movement distance during the operation of each step and start the next step. It is a feature.

The invention according to claim 6 is the software according to claim 5, wherein the trapezoidal speed trapping method is used as the pre-trapping acceleration / deceleration method.

The invention described in claim 7 is characterized in that, before calculating the trapezoidal velocity capture at each step, the target position is changed so that the moving distance becomes smaller at a fixed rate. 6. The software according to 6.

According to the invention described in claim 8, the ratio of reducing the moving distance is calculated by using both the parameter indicating the absolute moving distance and the parameter indicating the ratio to the original moving distance, and the smaller one is used. 7. The software according to claim 7, wherein the software is configured to select a value of. The invention described in claim 9 is a multi-axis machining in which a motor provided on each axis is sequentially driven so that each axis sequentially reaches a target position and a workpiece is machined by a tool attached to each axis. This machine uses an acceleration / deceleration method before interpolation that takes at least the position data sequence of the control force position, speed, and acceleration data sequences of each motor as input and outputs interpolated data with continuous speed. In addition, by shifting the target position of each step to a side closer to the start position of the step, the next step is started by overlapping a predetermined moving distance during the operation of the step for each step. This is a multi-axis processing machine characterized by the following.

The invention described in claim 10 is the multi-axis machine according to claim 9, characterized in that a trapezoidal speed trapping method is used as a pre-trapping acceleration / deceleration method in controlling each motor.

According to the invention described in claim 11, each motor is controlled so as to change its target position so that the moving distance becomes smaller at a fixed rate before calculating the trapezoidal speed interpolation at each step. The multi-axis machine according to claim 10, characterized by the following.

According to the invention described in claim 12, in the control of each motor, both the parameter indicating the absolute moving distance and the parameter indicating the ratio to the original moving distance are used to determine the ratio of decreasing the moving distance. The multi-axis machining apparatus according to claim 11, wherein the multi-axis machine is used to calculate and select a smaller value. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a block diagram showing a system configuration of a spring forming machine to which the method of the present invention is applied.

FIG. 2 is a block diagram showing software contents.

FIG. 3 is an explanatory diagram showing a screen configuration by the software.

FIG. 4 is an explanatory diagram showing a state in which a text file is opened by the software.

FIG. 5 is a flowchart showing the entire calculation processing by the software.

FIGS. 6 (a), (b) and (c) are graphs showing trapezoidal speed interpolation techniques. FIG. 7 is a flowchart showing details of a calculation processing method for one step by the software.

FIG. 8 is a flowchart continued from FIG.

FIG. 9 is a flowchart following FIG.

FIGS. 10 (a), (b) and (c) are graphs for explaining the method of capturing a straight line.

FIG. 11 is a flowchart showing an overlap processing procedure.

FIG. 12 is an explanatory diagram showing the relationship between original data, overlap data, and storage contents in the same processing procedure.

FIG. 13 is a time chart showing the operation during trapezoidal speed capture.

FIGS. 14 (a) and (b) are time charts showing the operation characteristics of each axis before and after the overlap processing. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. This will be described in detail. FIG. 1 is a system diagram showing a hardware configuration when the present invention is applied to a spring forming machine.

In the figure, 1 is a spring forming machine, and 2 is a controller for operating the spring forming machine 1 according to a predetermined program procedure. The controller 2 is connected to the personal computer 4 via the IZO port 3 and sequentially drives the molding machine 1 in accordance with the program contents generated by the software built in the personal computer 4.

Reference numeral 5 in the figure is a teaching box for manual input such as axis selection and speed selection, which is connected to the operation panel 2 via the I / O port 3 and is operated by a manual operation of a manual pulse handle or the like. , And the molding machine 1 is operated.

In the spring forming machine 1, a plurality of tool units 14 for cutting and bending are radially arranged around the tile 12 for supplying the wire W so as to be able to advance and retreat toward the tile 12. This is a multi-axis application machine in which a tool holding plate 16 provided with a plurality of tools for winding and bending is arranged so as to be able to advance and retreat toward the tile 12, and the wire W supplied from the quill 12 is programmed. It is added in accordance with. ■

The above-described molding machine 1 has, for example, eight-axis tools, and the relation between the following axis symbols and operations is set for each axis.

Ζ axis · · · Wire feed, C axis · · 'Cutoff, I axis · · · Quinole, W axis · ·' Unit advance / retreat, υ axis · · · Unit rotation, κ axis · 'Tool rotation, Υ axis · · · Servo slide, X axis · · 'Curling.

The software built in the personal computer 4 includes various means shown in FIG. That is, image display means 401 for displaying in a table and graphic format on the display screen of the personal computer 4 and the axis for inputting to an input field formed on the image by an operator using a mouse, a keyboard or the like. Shape and numerical value input means 402 according to the symbol, conversion means 403 and editing means 404 into an operation program according to the input contents, and execution possibility for judging whether the created operation program is executable or not Judgment means 405, conversion means 406 for converting the obtained operation program into command data of each axis by code, and execution instruction to the controller 2 by operating the execution key by the operator. The instruction means 407 and the overlap amount setting means 408 are included in the contents.

Then, the operator designates the processing shape element with the mouse in an interactive manner and sequentially repeats the numerical key input along the display screen, thereby generating a drive program for each step corresponding to the numerical input. Fig. 3 shows the actual screen configuration of the above software. This screen displays a menu bar, title bar, toolbar, etc. at the top of the display screen, similar to the ordinary Windows screen, with the first table 20 on the upper left inside, and figures and descriptions of each part on the right. The first graphic display column 22 described above is displayed, the second table 24 is displayed in the lower row, and the second graphic display column 26 is also displayed.

Among them, Table 1 shows the case where the operator specifies the dimensions by inputting numerical values while actually specifying the processing shape elements, and the step numbers 01, 02, and 03 on the left side of the vertical axis along the processing procedure. · · · · Are displayed in a column, and the contents of the command and the associated feed length, forming direction, bending R, bending angle, OD (s), OD (E), number of turns, forward and reverse LR, Items such as gold LR and winding sensor are displayed in a row, The inside of these boxes is separated by vertical and horizontal firewood lines. The first figure display field 22 displays the side view and the front view of the quill 12 and the parameters of the machining shape element. In this figure, the parameters on the same screen are changed and displayed every time the machining shape element is selected. You.

The second table 24 shows an automatic conversion table in the operation program related to the first table 20.The actual axis drive numbers 001, 002, 003 Axes are displayed in columns on the left side as axes, labels, full synchronization, speed, and ぴ display of 1 to 8 axes, axis names and home position HP under them are displayed in rows at the top of the display, and these are surrounded by columns and columns Since the inside is divided by vertical and horizontal lines, when input is made in the first table 10 in the upper row, after the conversion operation, the motion is converted to the movement of each axis and the movement distance for each step and the display is performed .

In Tables 20 and 24, horizontal and vertical scroll bars are displayed along the vertical direction on the right side of the screen, and can be moved by the cursor.

In addition, the second graphic display column 26 is not normally displayed, but when the shape display button in the task bar is clicked with a mouse, a three-dimensional graphical representation of a shape according to the input content is displayed.

Therefore, after the operator performs the numerical value and input work as shown in the figure while looking at the above screen, after specifying the number of products to be manufactured, by pressing the execution key, the molding machine 1 is set in accordance with the program contents. It drives and manufactures a spring with the shape according to the input contents. ·

If the program contents include the contents that cannot be executed, a warning is issued and the setting is made so that the program cannot be executed. This is the case, for example, in the case where the three-dimensional shape of the spring obtained as a result of instructing the bending of each part protrudes to the back side of the tile 12 and interferes with the face plate, or has dimensions or positions where each tool cannot reach. In this case, correction processing such as rewriting the numerical value is performed again, and if the result is correct, the execution can be performed.

At the time of this execution, the operations of the respective axes are overlapped by the overlap amount specified in advance by the overlap amount setting means 408. FIG. 4 shows a specific screen configuration of the setting means 408. In this example, a text file 28 in which parameters for “profile conversion” are described is opened on a Windows screen.

The window titled “Proiile. Par—Notepad” in the center of the screen corresponds to that.

Here, "profile conversion" is a sequence of movement commands for a motion controller that generates continuous speed data by giving a position sequence and speed 'acceleration for each axis, and actually controls the actuators of each axis. This is the process of converting to.

By changing the setting values in this text file, it is possible to control the amount of overlap optimally for each machine or production target.

The contents of the exemplified “Proiile. Par” are as follows.

pass-areata], pass-ratio [j] force S, and ohno-lap settings.

pass—area [j] is the maximum amount of overlap of the (j + 1) th axis.

At each step, if the displacement Xpass-ratio [j] X 0.01 is greater than this maximum overlap, the maximum overlap is carried over to the next step.

In this embodiment, the unit of pass-area [j] is 0.001 mm for a linear axis and 0.001 ° for a rotary axis. In the example shown,

Axisl (Z) 2.000mm

Axis2 (C) 150.000 °

Axis3 (K) 150.000 °

Axis4 (U) 150.000 °

Axis5 (W) 2.000mm

Axis6 (I) 150.000 °

Axis7 (X) 150.000 °

Axis8 (Y) 150.000 °

Where the linear axis is 2mm and the rotary axis is 150 °.

pass—ratio [j] specifies the amount of movement to move to the next step after reaching that point with respect to the (j + 1) axis, expressed as a percentage of the original movement amount of that step. I have.

Also, in the example in the figure, the setting is 80% for all axes, so the takt time is 80% of the input value. FIG. 5 shows the processing procedure in the software of the profile conversion processing. First, the setting of the maximum acceleration and the amount of overlap of each axis is read from the text file 28 describing the parameter file (ST1). Next, the target position and target speed of each axis for each step are read from the additional program file storing the operation and moving distance of each axis displayed in the second Table 24 (ST2).

This step is initialized as the first step, the current position is set to the home position, the current speed is set to 0 (ST3 to ST5), and the calculation processing for one step is performed (ST6). After the processing is completed, whether the current step is the final step or not ST7) is NO, that is, if it is not the final step, the calculation processing for the next one step is repeated again (ST8). To end. Next, before describing the calculation processing for one step in ST6 in FIG. 5, a calculation method during trapezoidal velocity capture will be described.

As described above, trapezoidal speed interpolation means that the current position and current speed are known, a series of target position and target speed are given, and the speed is assumed to be continuous assuming that the acceleration of each axis is specified. In this method, the speed change up to each target position in the sequence is determined sequentially as a piecewise linear function.

Fig. 6 shows the operation of one step of continuous speed data to be output by trapezoidal speed interpolation. First, (a) shows a time chart for one step before the profile conversion process, in which the vertical axis represents speed and the horizontal axis represents time. In this case, irrespective of the current speed, the speed becomes 0 at the target position with the target speed kept constant from the start to the stop until the motion stops, but this kind of speed discontinuous operation is impossible in reality.

On the other hand, there are roughly two patterns of speed change when performing trapezoidal speed interpolation processing. The first is, as shown in (b), a pattern in which the speed is 0 when the vehicle reaches the target position, that is, a pattern that temporarily stops (hereinafter referred to as the first pattern), and the next target position on that axis is the current target position. Used when the target position is invariable or the direction of movement is reversed.

The second is a pattern in which the vehicle is moving at the target speed without stopping when it reaches the target position (hereinafter referred to as the second pattern) as shown in (c), and the next target position is also the current pattern. Used when it is in the same direction as the movement direction.

The first pattern is used to accelerate or decelerate from the current speed to the target speed. The following three times are prepared as data: time to move at the target speed, time to move at the target speed, and time to decelerate from the target speed to speed 0. The three are referred to as an initial acceleration / deceleration operation, a constant speed operation, and a deceleration stop operation, respectively.

In the second pattern, two times, the time of the initial acceleration / deceleration operation and the time of the constant speed operation, are prepared as data.

The fact that the time data of the deceleration stop operation is 0 can be used as an expression of the second pattern.

In the first pattern, the current position and current speed used when moving to the target position of the next step in the sequence are determined as the target position and speed 0 of the current step.

In the second pattern, the current position and current speed used when moving to the target position of the next step in the sequence are determined as the target position of this step and the target speed of this step. However, the speed has a positive or negative sign determined by the moving direction of the current step.

When the current position and the target position are determined, the moving direction is determined, and accordingly, the target speed is determined with a plus or minus sign. If the current speed and target speed are determined with positive and negative signs, the speed difference is determined with positive and negative signs.

If the speed difference and the time for accelerating or decelerating from the current speed to the target speed are determined, if the time data is not 0, the acceleration for accelerating or decelerating is determined. If the time data is 0, it means that acceleration or deceleration is unnecessary, and the acceleration may be indefinite.

If the target speed and the time to decelerate from the target speed to speed 0 are determined, if the time data is not 0, the acceleration to decelerate is determined. If the time data is 0, it means that deceleration is not required, and the acceleration is not fixed. No.

As described above, if the three time data and the required acceleration are determined, the instantaneous target position can be calculated by the second-order piecewise polynomial at most.

The processing for one step described here is based on the given current position, current speed, target position and speed given the initial acceleration / deceleration operation, constant speed operation, deceleration stop operation time, and target speed used during constant speed operation. It is an algorithm that is automatically determined from the acceleration and acceleration. 7 to 9 show the detailed calculation processing procedure of ST6 in FIG. 5 based on the above assumptions.

First, as shown in FIG. 7, the method of the present invention calculates the moving direction from the target value of the current step and the target value of the next step. First, the overlap processing which is a main part of the present invention is performed. Go to rewrite the target position. This overlapping processing procedure will be described later in detail. In the initial calculation, the acceleration is calculated assuming the maximum acceleration of each axis (ST 101, 102).

If the moving direction of the next step is reverse or the next step does not move (ST 103), select the first pattern (ST 104) (set the bit of the first pattern). If not, the second pattern (ST 105) is selected (bits of the second pattern are set).

In the case of the first pattern, the movement time of the deceleration stop operation is calculated from the target speed and the acceleration, the speed difference is calculated from the target speed and the current speed, and the movement of the initial acceleration / deceleration operation is calculated from the speed difference and the acceleration. Calculate the time.

Further, in the case of the second pattern, after setting the movement time of the deceleration stop operation to “0”, a speed difference is calculated from the target speed and the current speed in the same manner as described above. The movement time of the initial acceleration / deceleration operation is calculated from the speed difference and the acceleration.

In any case, the moving distance of the initial acceleration / deceleration operation is calculated from the initial speed, acceleration, and movement time by the formula of uniform acceleration movement (ST106), and the moving distance of the deceleration / stop operation is calculated (ST107).

Since the acceleration is adjusted to the maximum acceleration of the motor as described above, it is constant, and the target speed is given, so that the above calculation can be easily executed.

Next, the moving distance of the constant speed operation is calculated from the results of STs 106 and 107 (ST108), and the moving time of the constant speed operation is calculated from the results (ST 109).

Here, it should be noted that each procedure in the processing for one step is performed for each axis. Therefore, in the case of the spring forming machine 1, the calculation processing is for a total of eight axes.

After ST109, in FIG. 8, the movement time of the other axis is adjusted to the axis having the largest movement time among the above axes. As a result, if the target speed is not changed on the axis whose travel time is adjusted to the other axes, Tsujimi will not match. Therefore, a new target speed must be found. In this case, tentative calculation is performed with the current speed kept unchanged during the initial acceleration / deceleration operation (ST110, 111).

According to the first pattern or the second pattern as described above (ST112), in the case of the first pattern, the time required for the deceleration stop operation, the distance required for the deceleration operation, and the moving distance for the constant speed operation are calculated. (ST113).

In the case of the second pattern, the entire distance is operated at a constant speed (ST114). In any of the patterns, the moving time of the constant speed operation is calculated from the distance and the speed of the constant speed operation obtained (ST115). This result is compared with the determined maximum travel time value (ST116), and if it is large, it is determined that the speed is too low (acceleration has the same sign as the travel direction). If it is small, the speed is too fast. (Acceleration has a different sign from the moving direction) (ST118).

In any case, one of the first and second patterns is determined (ST 119). In the case of the first pattern, the target speed in the first pattern is obtained (ST120). The target speed in two patterns is obtained (ST121). The method of obtaining the target speed in the case of the first pattern is based on a method of obtaining a solution of the following equations (1) to (4).

(1) Moving distance (known) = Moving distance of initial acceleration / deceleration operation (unknown)

+ Constant speed movement distance (unknown)

+ Travel distance for deceleration stop operation (unknown)

(2) Travel time (known) = Initial acceleration / deceleration operation time (unknown)

+ Constant speed operation time (unknown)

+ Deceleration stop operation time (unknown)

③ Travel distance of initial acceleration / deceleration operation

= U current speed (known) + target speed (unknown)) X Initial acceleration / deceleration operation time Z2

移動 Movement distance for constant speed operation = Target speed X—Time for constant speed operation

移動 Travel distance of deceleration stop operation

= (Target speed X Time of deceleration stop operation) / 2

⑥Target speed = Current speed + (Acceleration X Initial acceleration / deceleration operation time) ⑦Final speed = target speed + (acceleration X time of deceleration stop operation) The method of obtaining the target speed in the case of the second pattern is based on a method of obtaining a solution of the following equations ① to ⑤.

+ Constant speed movement distance (unknown)

+ Constant speed operation time (unknown)

③ Travel distance of initial acceleration / deceleration operation

= ί (current speed (known) + target speed (unknown)) X Initial acceleration / deceleration operation time 2

移動 Movement distance for constant speed operation-Target speed X-Time for constant speed operation

⑤Target speed = current speed + (acceleration X time of initial acceleration / deceleration operation) Here, it should be noted that each step in the processing for one step is performed for each axis. Therefore, in the case of the spring forming machine 1, the processing is performed for a total of eight axes.

Next, in FIG. 9, it is determined whether or not it is the case of straight line capture (ST122). If Yes, the acceleration / deceleration time is adjusted to the maximum axis of the eight axes, and then the other axis is set. When decelerating and stopping from a stop state, the time of the initial acceleration / deceleration operation and the time of deceleration stop operation are the same, so the following expression is obtained when the expression representing the entire distance is obtained (ST123). Overall distance = (constant speed time + deceleration stop time) X target speed Therefore, the formula that expresses the target speed is: target speed = total distance / (constant speed time + deceleration stop time). Since the overall distance is not different from the known target position, the target speed is obtained by this equation (ST123).

The reason why linear interpolation is necessary is because there are the following problems. FIG. 10 shows a process for drawing a trajectory moving from the position A to the position B on, for example, an XY table. As shown in FIG. However, if the initial acceleration / deceleration time and deceleration stop time are different on the X-axis and Y-axis as shown in (b), the trajectory moves from position A to position B, The trajectory is not a straight line, as shown by the broken line in (a), but a straight line. Therefore, as shown in (c), the initial acceleration / deceleration time and the deceleration stop time are aligned on the XY axis, and the movement is synchronized from the A position to the B position by synchronizing the movements.

Therefore, in the case of this linear interpolation, the acceleration in the initial acceleration / deceleration operation and the acceleration / deceleration stop operation does not always coincide with the maximum acceleration.

If the travel time or travel distance becomes negative in the above calculation process, it is physically impossible, and an error is generated.

It is determined whether recalculation is necessary or not based on whether an error has occurred (ST124). If NO, the calculation for one step is completed, and the process proceeds to the calculation processing of the next step. (See Figure 5).

If it is YE S, the target speed is automatically reduced while reducing the target speed with an appropriate step size. The calculation is repeated (ST125), and the calculation from ST101 in FIG. 5 is repeated again. If NO in ST122, that is, if it is not linear interpolation, jump to ST124. This is the case where the trajectory from the point A to the point B may or may not be a straight line, that is, it is only necessary that the target position coincides. In this case as well, it is determined whether or not there is an error in the same manner as described above, and whether or not recalculation is necessary (ST124). If NO, the calculation for one step is completed, and the next The process proceeds to step calculation processing. As described above, as a practical problem between trapezoidal speed traps, if the speed difference is too large, it may not be possible to accelerate to the target speed with the acceleration allowed for the axis, or it may not be possible to decelerate to a stop by the target position. . In case such an error occurs, recalculation is performed automatically while reducing the target speed at an appropriate step size. In practice, recalculation may be performed with the rate reduced by 1%. FIG. 13 shows the operating characteristics of each axis independently by the above calculation process, in which the vertical axis represents speed and the horizontal axis represents time. In this case, the trapezoidal acceleration / deceleration of each step repeats the operation characteristic of the second pattern, and reaches the target position at the speed 0 by the operation of the first pattern in the final step. Next, the above-described overlap processing method will be described. First, before calculating the trapezoidal velocity capture for a certain step, the target position is changed so that the moving distance becomes smaller at a certain rate. Specify how much the moving distance should be reduced using parameters.

There are two ways to specify the travel distance: the absolute travel distance and the original travel distance. There is a method of specifying the distance in terms of a percentage. In practice, it is better to specify both, and select the smaller one.

When an axis is overlapped, the original target position of that axis is stored, and in the next step, the original target position of the previous step that was stored when the axis did not move, that is, Move to the current position of.

Note that when the motion trajectory of each axis needs to match the programmed trajectory as in the in-position check mode, when the axis movement direction is reversed, or in the case of the last step, the overlap will occur. Should be banned. Specifically, the overlap prohibition processing is performed by writing a check mark in the “Complete synchronization” column in Table 24 of Table 2 in FIG. In this embodiment, a check mark is displayed in the column of complete synchronization in step 007 of the second table 24 in FIG. The above procedure is shown as a processing procedure in the flowchart of FIG.

First, it is determined whether the in-position check or the axis movement direction is reversed or the last step (ST201), and if NO, the movement distance is calculated when the overlap is specified as a percentage of the movement distance. (ST202) Also, the travel distance when the one burlap is specified as the absolute travel distance is calculated (ST203). Then, it is determined which is smaller (ST204), and if the ratio is smaller, the ratio of the moving distance is adopted (ST205). Conversely, if the absolute distance is smaller, the absolute moving distance is adopted (ST206). Next, the original target position is stored in the memory for the next step (ST207). If YES in ST201, jump to ST207. Then, the target position is rewritten to the one after the overlap (ST208). The above processing can be explained by the relationship shown in FIG.

First, assuming that the original data is provided sequentially from step 1 and the 80% overlap processing is set, the moving distance is reduced to 80% in each step in the overlapped state. The memory previously stores the original target position for the next step, and sets the position obtained by reducing the distance from the stored content to the target position of the next step to 80% as the target position after the overlap. The moving distance of each step is always set to 80% of the original moving distance. Next, it is determined whether or not the target position does not move in this step and overlap in the previous step (ST209). If YES, the stored target position is reset as the target position in this step, and (ST210) ) Return to calling source ST 201 again. If NO, the process directly returns to ST201 of the caller.

The determination in ST209 is made based on whether or not the storage data of the target position exists in the memory. The setting of the above-described overlap processing is specifically performed by writing to the text file 28 on the Windows screen, and once set, the setting is maintained unless rewritten. FIGS. 14 (a) and (b) show an example of a time chart showing the operation characteristics of each axis before and after the above-described overlap processing.

First, in (a), each axis is operated alternately and sequentially without overlap. In this case, the movement of one axis completely reaches the target position. Then, the movement of the other axis is started.

In the original data, (b) shows the operating characteristics of each axis when 80% overlap processing is applied. The axial force that did not move in the previous step, 80% of the other axis The invocation at the location is repeated and the last step is processed without overlap.

In this way, after the overlap processing, the next operation starts at the 80% position before the completion of the position operation, and the operation time for each step can be reduced by that time. Although this reduction time is not a great reduction time for each step, the normal processing step for one processing reaches 100 to 500 steps, so the tact time for each processing can be reduced sufficiently. Since the number of products produced reaches several thousand, the improvement in total productivity will be very large. The overlap operation is checked at a low speed using a teaching box or the like. If a problem such as interference between tools occurs, the percentage or the target position before the overlap operation may be changed.

In the above embodiment, the command data for each axis can be generated by specifying the shape while confirming the shape on the Windows screen and inputting a numerical value, but other command means such as a G code can also be used. Of course there is. As described above, according to the motor control method in the multi-axis machining apparatus of the present invention, the operation of each operation step of each axis can be overlapped, and the tact time for each machining can be significantly reduced. Can be planned. Also fast Since there is no decrease in the trajectory accuracy due to the degree change, the setup time during programming can be significantly reduced. Industrial Applicability In the embodiment, the case where the present invention is applied to a spring forming machine has been described. However, the present invention can also be applied to other multi-shaft plastic working machines that use many camshafts and the like and other multi-shaft working machines. It is.

Claims

The scope of the claims

1. A method of controlling a motor in a multi-axis machine, in which a motor provided on each axis is sequentially driven to sequentially reach each target position of each axis and work is processed by a tool attached to each axis. ,

A pre-capacity acceleration / deceleration method is adopted, in which at least the position data series of the position, velocity, and acceleration data series is input, and interpolated intermittent data is output, and the target position for each step is determined. Motor control in a multi-axis machining center characterized by shifting to the side closer to the start position of a step so that the next step is started for each step by overlapping the specified movement distance during the operation of that step. Method.

2. The method for controlling a motor in a multi-axis machine according to claim 1, wherein the acceleration / deceleration method before interpolation is a trapezoidal speed interpolation method.

3. The multi-axis machine according to claim 2, wherein, before calculating the trapezoidal speed interpolation of each step, the target position is changed so that the moving distance becomes smaller at a constant rate. Motor control method in

4. Calculate the ratio of decreasing the moving distance using both the parameter indicating the absolute moving distance and the parameter indicating the ratio to the original moving distance, and select the smaller value. 4. The method for controlling a motor in a multi-axis machine according to claim 3, wherein:

5. By sequentially driving the motors provided for each axis, The software for motor control of a multi-axis machine that processes workpieces with tools attached to each axis

At least a position data sequence of the position, speed, and acceleration data sequences is used as an input, and a pre-capture acceleration / deceleration method that outputs interpolated data with continuous speed is adopted. Software that is characterized by shifting to a side closer to the start position of the step so that each step overlaps a predetermined moving distance during the operation of the step and starts the next step.

6. The software according to claim 5, wherein a trapezoidal speed capture method is used as the acceleration / deceleration method before interpolation.

7. The software according to claim 6, wherein the target position is changed so that the moving distance is reduced at a constant rate before calculating the trapezoidal velocity capture at each step.

8. Calculate the ratio of decreasing the moving distance using both the parameter indicating the absolute moving distance and the parameter indicating the ratio to the original moving distance, and select the smaller value. 8. Software according to claim 7, characterized in that:

9. A multi-axis processing machine that sequentially drives a motor provided on each axis so that each axis sequentially reaches a target position and processes a workpiece with a tool attached to each axis.

Control of each motor is controlled by a small number of position, speed and acceleration data series. At the very least, a data sequence of positions is used as input, and the acceleration / deceleration method before interpolation is used to output interpolated data with continuous speed, and the target position of each step is shifted to the side closer to the start position of that step. A multi-axis machine wherein each step is performed by starting a next step by overlapping a predetermined moving distance during the operation of the step.

10. The multi-axis machine according to claim 9, wherein a trapezoidal speed trapping method is used as a pre-trapping acceleration / deceleration method in controlling each motor.

1 1. Each motor is controlled so as to change its target position so that the moving distance is reduced at a fixed rate before calculating the trapezoidal speed capture at each step. The multi-axis processing machine according to 10.

1 2. According to the control of each motor, the ratio of decreasing the moving distance is calculated using both the parameter indicating the absolute moving distance and the parameter indicating the ratio to the original moving distance, and the smaller one is calculated. The multi-axis machining apparatus according to claim 11, characterized in that a value is selected.