JPH06348328A - Arc interpolating method of cnc controller - Google Patents

Abstract

PURPOSE:To provide the arc interpolating method which can perform arc interpolation at a high speed. CONSTITUTION:When acceleration values alphax and alphay are both less than permissible acceleration values alphaxmax. and alphaymax., the arc interpolation is performed at a command speed given by a machining program (S5, S6, and S7). If one of the acceleration values alphax and alphay exceeds the permissible acceleration value alphaxmax. or alphaymax., the acceleration of the axis on the side the permissible acceleration is exceeded is limited to the permissible acceleration and the other axis is made to follow up it (S5, S6, and S11) (S5, S8, and S10). When the acceleration values alphax and alphay both exceed the permissible acceleration values alphaxmax. and alphaymax., acceleration alphay when the acceleration alphax is limited to alphaxmax. is found, but when alphay does not exceeds alphaymax., the acceleration alphax is limited to alphaxmax. and the Y axis is made to follow up it (S5, S8. S9, and S10). When the found acceleration alphay exceeds alphaymax., the acceleration alphay is limited to alphaymax. and the X axis is made to follow up it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a circular interpolation method in a CNC controller.

[0002]

2. Description of the Related Art As a circular arc interpolation method in a CNC controller, it is assumed that the acceleration at the quadrant boundary in the machine coordinate system is the maximum, and the allowable acceleration preset according to the characteristics of the servo motor and the radius of the circular arc to be interpolated. A method is known in which the clamp speed is calculated based on the above, and the tool is interpolated at the constant clamp speed.

For example, if an interpolation operation is performed on a circular arc shown by the alternate long and short dash line in FIG. 3, the boundary between the first quadrant and the fourth quadrant, that is, the X-axis direction (θ = 0 °). Since the acceleration at is assumed to be the maximum acceleration, this maximum acceleration is set as the allowable acceleration αmax. Must be included in the range.

Here, the radius of the circular arc is r, and the command speed is F =
rω (where ω is the angular velocity), the tool current position with respect to the center of the arc is (x, y), and the acceleration in the X-axis direction corresponding to the tool current position is αx, the centripetal direction acceleration rω ² is the x-axis. Since the projected acceleration is equal to αx and the commanded speed F is given by rω, the value of αx can be obtained by the equation (1).

[0005]

[Equation 1] Further, the maximum acceleration, that is, the tool moving speed Fc corresponding to the acceleration when θ = 0 °, is x = r, αx =
αmax. (permissible acceleration of servo motor) is equal to the value obtained by solving for F, and can be obtained by the equation (2).

[0006]

[Equation 2] In the conventional circular interpolation method, this speed Fc is set as the clamp speed, and the circular interpolation of the tool is performed at a constant speed.
The clamp speed Fc is a value regulated by the allowable acceleration αmax. Of the servo motor for one axis, which is far higher than the tool moving speed obtained by simultaneously driving the X-axis and Y-axis servo motors within the allowable acceleration limit. Small. Especially when the value of θ is in the vicinity of (n / 2) · π,
As a result, the moving speed of the tool is suppressed more than necessary, which causes a problem that the tool circular interpolation cannot be performed at high speed.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a circular interpolation method in a CNC controller capable of eliminating the above-mentioned drawbacks of the prior art and performing circular interpolation at high speed.

[0008]

According to the circular interpolation method of the present invention, the current position of each axis with respect to the center of the circular arc is detected every predetermined period when the circular interpolation processing is executed, and the current position of each axis and the circular arc radius are detected. Based on the command speed and the command speed, the acceleration for each axis required to realize the command speed is obtained, and if all the accelerations for each axis are within the range of the allowable acceleration set for each axis. , While controlling the drive of each axis at the commanded speed, and when any of the accelerations for each axis exceeds the allowable acceleration range set for each axis, each of the preset values for realizing circular interpolation is set. The object is achieved by calculating the clamp speed based on the permissible acceleration for each axis, the current position of each axis, and the arc radius, and drivingly controlling each axis at the clamp speed.

[0009]

In order to realize the command speed based on the current position of each axis, the arc radius and the command speed, the current position of each axis with respect to the center of the arc is detected every predetermined period when the circular interpolation processing is executed. Calculate the required acceleration for each axis.

If all of the obtained accelerations for each axis are within the range of the allowable acceleration set for each axis, each axis is drive-controlled at the command speed.

Further, when any of the accelerations for each axis exceeds the allowable acceleration range set for each axis, the allowable acceleration for each axis and the above-mentioned allowable accelerations set in advance to realize circular interpolation. The clamp speed is calculated based on the current position of the axis and the radius of the arc, and each axis is drive-controlled at the clamp speed. Although this clamp speed is smaller than the command speed, it is the maximum moving speed that can be obtained while maintaining the coordinated operation required for circular interpolation.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a CNC for carrying out the method of the present invention.
3 is a block diagram showing hardware of the control device 10. FIG.
The processor 11 is a processor that controls the CNC control device 10 as a whole, reads a system program stored in the ROM 12 via the bus 21, and controls the CNC control device 10 according to the system program. The RAM 13 stores temporary calculation data, display data, various data input by the operator via the CRT / MDI unit 70, and the like. The CMOS memory 14 is backed up by a battery (not shown), C
It is configured as a non-volatile memory that retains a stored state even when the power of the NC control device 10 is turned off, and a machining program or CRT /
A machining program or the like input via the MDI unit 70 is stored. In addition, various system programs for executing the processing in the edit mode and the processing for the automatic operation required for creating and editing the machining program are written in the ROM 12 in advance.

The interface 15 is the CNC controller 1.
This is an interface for an external device connectable to 0, and is connected to an external device 72 such as a paper tape reader, a paper tape puncher, and an external storage device. Processing programs are read from a paper tape reader or external storage device,
Further, the processing program edited in the CNC control device 10 can be output to a paper tape puncher or an external storage device.

A PMC (Programmable Machine Controller) 16 controls an auxiliary device on the machine tool side, for example, an actuator such as a robot hand for tool change, by a sequence program built in the CNC control device 10. That is, the M function commanded by the machining program,
In accordance with the S function and the T function, these sequence programs convert the signals into signals required on the auxiliary device side and output them from the I / O unit 17 to the auxiliary device side. This output signal activates auxiliary devices such as various actuators. Further, it receives signals from a limit switch on the machine tool main body and the auxiliary device side and various switches on an operation panel provided on the machine tool main body, performs necessary processing, and passes it to the processor 11.

Image signals such as the current position of each axis of the machine tool, alarms, parameters and image data are sent to the CRT / MDI unit 70 and displayed on its display. C
The RT / MDI unit 70 is a manual data input device equipped with a display, a keyboard, etc., and the interface 18 receives data from the keyboard of the CRT / MDI unit 70 and transfers it to the processor 11. The interface 19 is connected to the manual pulse generator 71 and receives pulses from the manual pulse generator 71. The manual pulse generator 71 is mounted on the operation panel of the machine tool main body, and is used for precisely positioning the movable part of the machine tool by controlling each axis by the distributed pulse based on the manual operation.

The axis control circuits 30 to 32 receive the movement command of each axis from the processor 11 and output the command of each axis to the servo amplifiers 40 to 42. The servo amplifiers 40 to 42 receive this command, and the servo motors 50 to 5 for the respective axes of the machine tool.
Drive 2 The servo motors 50 to 52 for the respective axes have a built-in pulse coder for position detection, and the position signal from this pulse coder is fed back as a pulse train. In some cases, a linear scale is used as the position detector. Further, a speed signal can be generated by F / V (frequency / speed) conversion of this pulse train. In FIG. 1, description of feedback of these position signals and velocity feedback is omitted.

The spindle control circuit 60 receives a spindle rotation command to the machine tool and outputs a spindle speed signal to the spindle amplifier 61. The spindle amplifier 61 receives the spindle speed signal and rotates the spindle motor 62 of the machine tool at the commanded rotation speed. A position coder 63 is coupled to the spindle motor 62 by a gear or a belt, and the position coder 63 outputs a feedback pulse in synchronization with the rotation of the spindle, and the feedback pulse is read by the processor 11 via the interface 20. .

Next, the principle of operation of the circular interpolation method applied to the CNC controller 10 of this embodiment will be described.

First, it is assumed that an interpolation operation is performed on a circular arc as shown by the alternate long and short dash line in FIG. 3, the radius of the circular arc is r, the command speed is F = rω (where ω is an angular speed), and the center of the arc. If the tool current position is (x, y) and the X-axis direction acceleration corresponding to the tool current position is αx, the acceleration rω ^{2 in the} centripetal direction projected on the x-axis is equal to αx, and the command Since the speed F is given by rω, the value of the acceleration αx in the X-axis direction required to realize the command speed F can be obtained by the equation (1).

[0020]

## EQU1 ## Similarly, the value of the acceleration .alpha.y in the Y-axis direction required to realize the command speed F can be obtained by the equation (3).

[0021]

[Equation 3] Here, the allowable acceleration of the X-axis servomotor 50 is set to αxma
If the allowable acceleration of the x., Y-axis servo motor 51 is αymax., the tool can be circularly interpolated at the command speed F only when αxmax. ≧ αx and αymax. ≧ αy. That is, if either one of αx and αy exceeds the range of allowable accelerations αxmax. And αymax., The accelerations αx and αy in each axial direction required to realize the command speed F are simultaneously achieved. Therefore, it becomes impossible to perform normal circular interpolation with the command speed F.

Therefore, the acceleration αx in the X-axis direction is set to αxmax.
If the equation 1 is solved for F, the maximum value F ′ (equation 4) of the moving speed that can be realized within the range of the allowable acceleration αxmax. Of the X-axis servomotor 50, that is, the acceleration in the X-axis direction It is possible to obtain the maximum value F ′ of the moving speed when only αx exceeds the allowable acceleration.

[0023]

[Equation 4] Similarly, the acceleration αy in the Y-axis direction is set to αymax.
If the equation is solved for F, the maximum value F ′ (equation 5) of the moving speed that can be realized within the range of the allowable acceleration αy max. Of the Y-axis servomotor 50, that is, the acceleration αy in the Y-axis direction
Maximum value of moving speed F'when only exceeds the allowable acceleration
Can be asked.

[0024]

[Equation 5] Further, the acceleration αx in the X-axis direction and the acceleration α in the Y-axis direction
When each y exceeds the respective allowable accelerations αxmax. and αymax. at the same time, first, the maximum value F ′ of the moving speed when the acceleration αx in the X-axis direction is limited to αxmax. Is obtained, and F ′ obtained in F in the formula 3 is obtained.
Value is substituted to obtain the acceleration αy in the Y-axis direction when the acceleration αx in the X-axis direction is limited to αxmax. And
If this acceleration αy does not exceed the allowable acceleration αymax. In the Y-axis direction, that is, if the formula 6 is satisfied, the Y-axis servomotor 5 with respect to the X-axis servomotor 50
Since 1 can be followed, circular interpolation can be performed with the maximum value F ′ of the moving speed obtained by the equation (4). Further, if the formula 6 is not satisfied, the drive limit of the Y-axis servomotor 51 can be prioritized, and the circular interpolation can be performed with the maximum value F ′ of the moving speed obtained by the formula 5.
The maximum value F'of the moving speed thus obtained is the clamp speed.

[0025]

[Equation 6] FIG. 2 is a flow chart showing the outline of the processing for carrying out the above-mentioned circular interpolation method in the CNC controller 10 of the present embodiment, which is repeated every time the circular interpolation command is read by the processor 11 which executes the automatic operation mode processing. To be executed.

The processor 11, which has read the circular interpolation command from the machining program, first stores the coordinate values x0, y0 of the center of the circular arc, the circular arc radius r and the command speed F given by this command (step S1), Current position x1, y
1 is temporarily stored (step S2). Next, the processor 11 determines whether the interpolation operation corresponding to the current circular interpolation command is completed (step S3). If the interpolation operation is not completed, the current position x of each axis with respect to the arc center, y is obtained, the current position x, y of each axis, the arc radius r read in the process of step S1, and the command speed F
The equations 1 and 3 are executed based on the equation (1) to obtain the value of the acceleration αx in the X-axis direction and the value of the acceleration αy in the Y-axis direction required to realize the command speed F (step S
4).

Next, the processor 11 determines that the value of the acceleration αx in the X-axis direction required to realize the command speed F is the allowable acceleration αxmax. (CM of the X-axis servomotor 50.
It is determined whether or not it exceeds the value stored in the OS memory 14 (step S5). If not, the value of the acceleration αy in the Y-axis direction required to realize the command speed F is Y-axis servo. Allowable acceleration of motor 51 αymax. (CM
It is determined whether or not it exceeds the memory (stored inside the OS memory 14) (step S6). If the accelerations αx and αy are both within the ranges of the allowable accelerations αxmax. And αymax., The processor 11 sets the command speed F read in the process of step S1 as it is as the tool moving speed F ′ (step S7), and the moving speed F ′, A distributed pulse for executing circular interpolation is output to each of the X and Y axes (step S12).

If the determination result of step S5 is false and the determination result of step S6 is true, that is, only the value of the acceleration αy in the Y-axis direction required to realize the command speed F is obtained. Exceeds the allowable acceleration αymax. Of the Y-axis servo motor 51, the acceleration in the Y-axis direction αy
The value of is limited to the allowable acceleration αymax.
To obtain the maximum value F ′ of the moving speed when only the acceleration αy in the Y-axis direction exceeds the allowable acceleration (step S11), and to execute the circular interpolation on the X and Y axes based on the moving speed F ′. The distribution pulse of is output (step S12).

On the other hand, if the determination result in step S5 is true, that is, the value of the acceleration αx in the X-axis direction required to realize the command speed F exceeds the allowable acceleration αxmax. If it is determined that the value of the acceleration αy in the Y-axis direction required to realize the command speed F is the allowable acceleration αy of the Y-axis servo motor 51,
It is determined whether or not the maximum value is exceeded (step S8).
When the determination result in step S8 is false, that is, only the value of the acceleration αx in the X-axis direction required to realize the command speed F exceeds the allowable acceleration αxmax. Of the X-axis servomotor 50. The acceleration αx in the X-axis direction,
The value of is limited to the allowable acceleration α x max.
To obtain the maximum value F ′ of the moving speed when only the acceleration αx in the X-axis direction exceeds the allowable acceleration (step S10), and to execute circular interpolation on each of the X and Y axes based on the moving speed F ′. The distribution pulse of is output (step S12).

When the result of the determination in step S8 is true, that is, the accelerations αx and αy are both the allowable acceleration αx.
When the range of max., αymax. is exceeded, the current position x, y of each axis with respect to the center of the arc and the values of αxmax., αymax. It is determined whether or not is satisfied (step S9), and when the expression of Formula 6 is satisfied, that is, when the acceleration of the X-axis servomotor 50 is limited to αxmax., The Y-axis servomotor for the X-axis servomotor 50 is determined. If 51 can be followed,
The maximum value F ′ of the moving speed is calculated by the equation (4) (step S1
0), based on the moving speed F ', a distributed pulse for executing circular interpolation is output to each of the X and Y axes (step S1).
2). On the other hand, when the expression of the expression 6 is not established, the drive limit of the Y-axis servomotor 51 is given priority, and the maximum value F ′ of the moving speed is obtained by the expression of the expression 5 (step S11), and the moving speed F ′ is obtained.
Based on the above, a distribution pulse for executing circular interpolation is output to each of the X and Y axes (step S12).

Thereafter, the processor 11 repeatedly executes the same discrimination processing as described above in accordance with the change of the current position x, y of each axis with respect to the center of the circular arc until the interpolation operation corresponding to the circular interpolation command is completed. , X-axis, Y-axis acceleration αx, α
If both y are within the range of the allowable accelerations αxmax. and αymax., the command speed F read in the process of step S1 is used as it is as the tool moving speed F ′ to drive and control each axis.
Allowable acceleration αxma for either one of accelerations αx and αy
If the range of x., αymax. is exceeded, the maximum moving speed F ′ at which circular interpolation by cooperative operation of each axis is possible is obtained, and the combined moving speed of each axis is clamped to F ′ to drive and control each axis. It will be.

According to the circular interpolation method of this embodiment, the acceleration α of the X-axis servomotor 50 and the Y-axis servomotor 51 is
When both x and αy are in the range of allowable acceleration αxmax. and αymax., the tool can be circularly interpolated at the command speed F given by the machining program, and either acceleration αx and αy is allowable. Acceleration αxmax., Αy
When exceeding the max. (including the case where both are exceeded), the acceleration of the axis that exceeds the allowable acceleration is limited to the allowable acceleration and the other axis follows it. Tool movement can be performed at extremely high speed as compared with the conventional method.

[0033]

According to the circular interpolation method of the present invention, the acceleration for each axis required to realize the command speed is obtained, and if all the accelerations for each axis are within the range of the allowable acceleration, the command speed is obtained. While controlling the drive of each axis with, while any of the acceleration of each axis exceeds the range of allowable acceleration, the axis with lower acceleration capability is accelerated with the allowable acceleration and the other axis follows it. Since the circular interpolation operation is performed as described above, the circular interpolation can be performed at a higher speed than the conventional control method in which the acceleration at the quadrant boundary is assumed to be the maximum and the velocity is clamped.

[Brief description of drawings]

FIG. 1 is a block diagram showing hardware of a CNC controller according to an embodiment for carrying out the method of the present invention.

FIG. 2 is a flowchart showing an outline of processing of a CNC control device that implements a circular interpolation method according to an embodiment.

FIG. 3 is a conceptual diagram illustrating circular interpolation.

[Explanation of symbols]

 10 CNC control device 11 Processor 12 ROM 13 RAM 14 CMOS memory 18 Interface 21 Bus 50 X-axis servo motor 51 Y-axis servo motor

Claims (1)

[Claims] 1. A current position of each axis with respect to the center of a circular arc is detected at predetermined intervals when a circular arc interpolation process is performed by a CNC controller, and a command is issued based on the current position of each axis and the circular arc radius and command speed. Obtain the acceleration for each axis required to realize the speed, and if all the accelerations for each axis are within the range of the allowable acceleration set for each axis, then use the command speed for each axis. While performing drive control, when any of the accelerations for each axis exceeds the allowable acceleration range set for each axis, the allowable accelerations for each axis and the above-mentioned allowable presets for realizing circular interpolation are set. A circular arc interpolation method in a CNC control device, wherein a clamp speed is calculated based on the current position of an axis and the circular arc radius, and each axis is drive-controlled at the clamp speed.