JP3427800B2 - Numerical control unit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerical control device, and more particularly to a numerical control device in a machine tool having at least one spindle.

[0002]

2. Description of the Related Art A numerical control device executes a numerical control process based on a processing program instructed from a paper tape or the like,
Based on this processing result, the machine tool is driven and the work is machined as instructed.

FIG. 9 is a block diagram of essential parts showing a conventional numerical controller. Reference numeral 101 denotes a numerical controller, which includes an analysis processing unit 103, an interpolation processing unit 104, a machine control signal processing unit 106, a PLC circuit 105, an NC axis processing unit 180, a main axis processing unit 110, a data input / output circuit 120, Memory 107, parameter setting unit 108, and screen processing unit 109
, Analog output circuit 130, and encoder input device 1
It is composed of 31.

Further, the numerical control device 101 is connected to the servo drive device 201 via the data input / output circuit 120, drives the NC shaft 204 by position control, and moves it to a commanded position. Further, it is connected to the spindle drive device 301 via the data input / output circuit 120, or is connected to the inverter device 401 via the analog output circuit 130, and the spindle 304 or 404 is commanded by the speed control at the rotation speed. Rotate. Further, the spindle drive device 301
Has a position control function in addition to the speed control function. For example, as disclosed in JP-A-1-134605, the speed control and the position control are switched to rotate the main shaft or use the NC shaft as Some perform positioning.

Reference numeral 102 is a processing program, and the processing program 102 read from a tape reader or the like is stored in the memory 107. When executing the machining program 102, the machining program 102 is read from the memory 107 block by block and analyzed by the analysis processing unit 103. The code analyzed for each block is passed to the interpolation processing unit 104, and interpolation control, spindle control, auxiliary function control, etc. for each block are performed according to the code. The NC axis processing unit 180 controls the NC axis to perform positioning, interpolation feed, and the like according to the interpolation data. Spindle control unit 1
The reference numeral 10 controls the spindle instructed to rotate, stop, orient, etc., at the command rotation speed.

The servo drive device 201 includes a servo motor 2
02, and the position control by the position feedback from the detector 205 positions the NC shaft 204 at the feed speed commanded to the position commanded by the machining program.

The spindle drive device 301 includes a spindle motor 302.
And drives the main shaft 304 via a gear or the like. A detector 305 is attached to the main shaft 304, and the main shaft driving device 301 calculates the position data used for calculation of the command pulse of the synchronous feed and the thread cutting shaft based on the position feedback data input from the detector. , To the data input / output circuit 120. Further, the position control may be switched to the position control based on the position feedback data to perform the positioning control with the spindle 304 as the NC axis.

The inverter device 401 includes a spindle motor 40.
The main shaft 404 is connected to the main shaft 404 via a gear or the like.
Position data is input to the encoder input device 131 from the detector 405 attached to the main shaft 404, and is used for synchronous feed and calculation of command pulses for the thread cutting shaft.

Next, a conventional spindle control method will be described below with reference to the block diagram of FIG. The command rotational speed for the spindle 304 follows the spindle rotational speed command value described in the machining program 102. First, the spindle rotation speed command block described in the machining program 102 is read from the memory 107. Next, the read instruction is analyzed by the analysis processing unit 1.
In 03, the spindle number for which the rotation speed command has been issued and the command rotation speed are analyzed and passed to the interpolation processing unit 104. The interpolation processing unit 104 updates the spindle rotation speed command value to a newly commanded value through the machine control signal processing unit 106, and the PLC
By the completion signal from the circuit 105, the process proceeds to the next block. The spindle rotation speed command value is passed to the spindle control unit 110. Further, as the amount of the command rotation speed with respect to the maximum rotation speed of the spindle, the S analog value represented by the following equation is calculated.

(S analog value) = 4096 × (spindle command rotation speed) / (spindle maximum rotation speed)

In the case of a serially coupled spindle which is coupled and controlled via the data input / output circuit 120 like the spindle drive device 301, the spindle control unit 110 causes the command speed to
Spindle drive device 301 via data input / output circuit 120
To the spindle motor 302 with the spindle motor 302.
Drive at the commanded speed. Like the inverter device 401, coupled via the analog output circuit 130,
In the case of the analog coupled spindle to be controlled, the S analog value is passed to the machine control signal processing unit 106, and the analog output circuit 130 outputs a voltage obtained by the following formula according to the S analog value.

(Output voltage) = 10 × (S analog value) /
4096 [V]

The inverter device 401 changes the spindle speed according to the voltage value input from the analog output circuit 130, and drives the spindle 404 with the spindle motor 402.

[0014]

As described above, in the conventional numerical control device, the spindle motor 302 driven and controlled by the spindle drive device 301 is an induction type motor, which has a large installation range and a machine tool having the same. However, there was a problem that

Further, in the speed control for rotating operation, the responsiveness to a momentary load such as a load during cutting is not sufficient, so that the rotation speed greatly drops when a load is applied, and it is synchronized with the spindle position such as thread cutting. There was a problem that affects the accuracy of the machining.

Further, when performing the orientation or indexing operation of the spindle, a detector is attached to the spindle end, or
When a detector is attached to the motor end, the reference point for each rotation of the motor is the reference point for each rotation of the spindle, such as the gear ratio between the motor and the spindle is 2: 1, 4: 1, ... It was limited to matching. This is because when the detector is attached to the motor end, the reference point of the motor may not match the reference point of the spindle end, depending on the gear ratio between the motor and the spindle. This is because the phase at the spindle end cannot be calculated. Therefore, when the detector is attached to the motor end, the motor reference point is further regarded as the spindle end reference point, and the spindle rotates 2 rotations, 4 rotations, ... There has been a problem that the spindle rotates excessively during the orientation or indexing operation of the spindle, resulting in a longer machining cycle time.

There is also a case where the spindle drive device 301 is provided with a position control function in addition to performing a rotational operation by speed control, and the spindle is treated as an NC axis. However, the time for switching the control method between speed control and position control. However, there is a problem that the processing cycle time becomes long.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a numerical controller having a small-sized and high-power spindle.

A numerical control device according to the present invention is a numerical control device in which a servo motor for positioning and a servo drive device for controlling the position of the servo motor are combined,
A reference inclination amount for acceleration / deceleration is obtained from the limit rotational speed of the main spindle and a basic time constant, and a multistage acceleration / deceleration parameter set by multiplying the reference inclination amount by the inclination magnification of each of a plurality of preset stages, and A spindle acceleration / deceleration processing unit that sets an acceleration / deceleration command speed of the spindle according to an acceleration / deceleration pattern set in multiple stages by the multistage acceleration / deceleration parameter based on a command rotation speed of the spindle engaged with the servomotor; A speed position conversion circuit for integrating the command speed and converting it into a position command value for the servo drive device for driving the spindle.

[0020]

[0021]

In addition, the servo motor is NC while the position is controlled.
A spindle / NC axis control switching processing unit is provided for driving the shaft and the spindle and switching between a positioning operation by a positioning command for the NC axis and a rotating operation by a rotation speed command for the spindle.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1. 1 is a block diagram showing a numerical controller according to a first embodiment of the present invention. Figure 9
Compared with the block diagram in the spindle control of the conventional numerical control apparatus shown in FIG.
2. Instead of the inverter device 401 and the spindle motor 402, a servo drive device 801 and a servo motor 802 are installed, the spindle acceleration / deceleration processing unit 160, and the speed position conversion circuit 1
50 is provided in the spindle control unit 110, and a spindle servo parameter 151 and a multi-step acceleration / deceleration parameter 161 are provided in the memory 107. The same or corresponding parts as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted. Also, FIG.
Although omitted in FIG.
It is also possible to control 1 and the spindle motor 302, and the inverter device 401 and the spindle motor 402.

In FIG. 1, the servo parameter for the spindle 1
51 is transferred to the servo drive device 801, and the servo drive device 801 controls the position of the servo motor 802 according to the transferred parameters. Servo drive device 801
Are the servo drive device 201 and the servo motor 802,
Servo motor 202 and detector 805 are detector 205
And the same, respectively.

The spindle control method according to the present invention will be described below with reference to the block diagram of FIG. A block of the spindle rotation speed command to the spindle 804, which is commanded by the machining program 102, is read from the memory 107. Next, the read command is analyzed by the analysis processing unit 103 for the spindle number for which the rotation speed command was issued and the command rotation speed, and passed to the interpolation processing unit 104. The interpolation processing unit 104 updates the spindle rotation speed command value to a newly commanded value through the machine control signal processing unit 106, and the completion signal from the PLC circuit 105 advances the processing to the next block.

If there is a difference between the newly commanded spindle rotation speed command value and the previous spindle rotation speed command value, the spindle acceleration / deceleration processing unit 160 uses the acceleration / deceleration pattern according to the multistage acceleration / deceleration parameter 161. , Calculate the acceleration / deceleration command speed. The acceleration / deceleration command speed is converted by the speed / position conversion circuit 150 as a position change amount per unit time and added to the position command value. The spindle control unit 110 transfers the position command value to the servo drive device 801 via the data input / output circuit 120, and the servo drive device 801 controls the position of the servo motor 802 to rotate the spindle 804 instructed. Drive by number.

FIG. 2 is an explanatory diagram relating to multistage acceleration / deceleration of the spindle in the numerical controller of FIG. In the example of FIG. 2, the acceleration / deceleration pattern for speed control up to the maximum rotation speed is divided into seven. As for the dividing method, a portion that can approximate the speed control acceleration / deceleration pattern to a straight line is largely divided, and a largely curved portion is finely divided. The division method is set by the multi-step acceleration / deceleration parameter that determines the acceleration / deceleration pattern. spt, s
ptc1 to sptc7, spdiv1 to spdiv7
Represents a multi-step acceleration / deceleration parameter.

Spt determines a reference inclination amount for acceleration / deceleration, and sets an acceleration / deceleration time constant for the limit rotational speed of the spindle. sptc1 to sptc7 set the speed for switching the amount of inclination during acceleration / deceleration, and spdiv1 to spdiv7 are
As the inclination amount of acceleration / deceleration between the switching speeds, a magnification of the inclination with respect to the reference inclination amount is set. The command acceleration / deceleration pattern is determined by setting the parameters as described above. Although the number of divisions is 7 in the present embodiment, the number of divisions can be further increased to more finely set the multi-step acceleration / deceleration pattern.

FIG. 3 is a flowchart relating to the spindle acceleration / deceleration processing section 160. In S01, it is determined whether the motor is a servo motor. No processing is performed for the spindle motor. In the case of a servomotor, in S02, it is determined whether or not there is a difference between the speed instructed by the machining program and the actual acceleration / deceleration speed. If there is a speed difference, in S03, the acceleration amount according to the multistage acceleration / deceleration parameter is added to the acceleration / deceleration speed value to calculate the acceleration / deceleration speed. Next, in S04, a command pulse corresponding to the acceleration / deceleration command speed is calculated, and in S05, the position command value output to the servo drive device 801 is updated.

The spindle acceleration / deceleration processing unit 160 calculates an acceleration / deceleration speed command according to the determined acceleration / deceleration parameter. As shown in FIG. 4, the position command pulse amount per unit time corresponding to the command speed is calculated, added to the position command pulse, and output to the servo drive device, and the smooth multi-step of the spindle by the servo motor is performed. Acceleration / deceleration is performed.

That is, the spindle acceleration / deceleration processing unit 160 is configured so that the rotation speed instructed by the program is the current spindle control unit 11
If the rotation speed is different from 0, the acceleration / deceleration component determined by the parameter is added to the previous command speed to calculate the acceleration / deceleration speed. In addition, the speed position conversion circuit 1
Reference numeral 50 denotes a command value for integrating the acceleration / deceleration speed based on a gear ratio and a command unit to calculate a position command value and converting the speed command into a command value for position control. A certain speed command is converted into a position command which is command data of the servo drive device.

As described above, since the main shaft can be driven by the synchronous motor such as the servo motor, the installation range of the motor having the same output can be reduced as compared with the case where the conventional induction motor is used, and the machine tool can be made compact. Can be converted. Further, since a higher torque can be output as compared with the conventional spindle, the working application range can be widened. Further, since the servo drive device and the servo motor that drive the NC axis are used, the cost can be reduced. In addition, maintenance is easy. Also,
Since the spindle is rotated by the position control, the position is compensated for the speed fluctuation due to the load at the start of cutting.
It is possible to improve the accuracy at the start of thread cutting.

Further, by providing the multi-step acceleration / deceleration parameter for setting the acceleration / deceleration pattern in multiple steps, any acceleration / deceleration determined by the multi-step acceleration / deceleration parameter including the acceleration / deceleration pattern almost equivalent to the acceleration / deceleration of the induction motor is provided. The pattern can be realized.

Embodiment 2. FIG. 5 is a block diagram showing a numerical controller according to the second embodiment of the present invention. Compared to the first embodiment, the spindle control unit 110 includes a spindle phase calculation processing unit 170, and the memory 107 includes a reference position holding unit 1.
71, and is provided with a reference position initial setting unit 172 and an absolute position holding device 175. Further, the same or corresponding parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The detector 805 is attached to the servomotor 802, and the servomotor and the main shaft have a gear ratio n1: n2.
Are joined by. The detector 805 can detect the feedback position and the motor reference point (Z phase) for each rotation.

The servo drive device 801 transfers the relative position (hereinafter referred to as grid amount) from the reference point and the machine position pulse to the numerical control device 101 through the data input / output circuit 120. The servo drive device 801 includes an absolute position holding device 1
75 is attached so that the absolute position can be maintained even when the power is turned off.

FIG. 6 is an explanatory diagram showing the phase relationship between the motor and the spindle. A case where the gear ratio between the motor and the main shaft is 4: 5 is shown as an example in which the rotational position is replaced with a straight line. When detecting the rotation angle, the reference point is detected for each rotation, and the rotation angle is calculated from the position from the reference point. In the semi-closed system, the detector
The motor reference point can be detected. However, as can be seen from FIG. 12, the phase at the spindle end from the motor reference point differs depending on the detection point of the motor reference point, so operations such as orientation, indexing, and phase matching at the spindle end can be performed. There wasn't.

In order to solve the above-mentioned problems, the present embodiment is provided with means for calculating the spindle end reference point from the detected motor end reference point. As can be seen from FIG. 6, the phase difference between the motor reference point and the spindle end reference point changes in a specific cycle. That is, the motor and spindle are
When coupled with a gear ratio n1: n2, the motor is n2
The spindle makes n1 rotations for each rotation. Therefore, by holding the motor reference point for each rotation of the motor n2, the reference point can be treated as a reference point for each rotation of the spindle n1.

The reference position holding unit 171 monitors the passing of the motor reference point, and holds the position of the motor reference point passed every n1 rotations. In this embodiment, in order to maintain the spindle end reference point even after the power is turned on again, it is held in the memory, but it may be held in the detector or the like.
The reference position initial setting unit 172 is a setting unit for initializing the spindle end reference point during machine adjustment. The adjustment mode is selected by the parameter or the signal from the PLC circuit, and the feed reference point is set at the position of the phase where the spindle is the reference. The nearest Z phase at this time is set as the spindle end reference point. Further, the position pulse (grid amount) from the Z phase at this time is held as a phase shift amount from the spindle end reference point. The spindle phase calculation processing unit 170 calculates the spindle end phase from the difference between the reference point position held by the reference position holding unit 171 and the feedback position and the command pulse number per one spindle rotation obtained from the parameter, using the following formula. To calculate.

Θ = 2π × ((Pf-Pb) / Ls) θ: Spindle phase Pf: Feedback position Pb: Spindle reference point position Ls: Number of pulses per spindle rotation

Since the phase at the spindle end can be calculated from the feedback position and the command position at the commanded phase can also be calculated from the above expression, the amount of movement pulse from the current position to the command position can be calculated to determine the spindle. Performs operations such as orientation, indexing, and phase matching.

As described above, since the detector attached only to the motor end can calculate the phase of the main spindle end and perform the phase alignment such as the orientation at any gear ratio, the number of detectors at the main spindle end can be reduced. It is possible to reduce the size and cost of the machine.

Embodiment 3. FIG. 7 is a block diagram showing a numerical controller according to the third embodiment of the present invention. Compared to the second embodiment, the spindle / NC axis control switching processing unit 19
0, and the main shaft 804 is driven by the servo motor 202. Further, the same or corresponding parts as those in the second embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIG. 8 shows the spindle / NC axis control switching processing section 19
It is a figure which shows the flowchart of the control in 0. S3
At 1, it is determined whether the axis giving the command is a servo axis.
In the case of the spindle, the spindle control is performed in S36, and in the case of the servo axis, it is determined in S32 whether or not the spindle control servo motor. When the servo motor is not a spindle control servo motor, normal NC axis control is performed in S33. When using the servo motor for spindle control, S3
In step 4, depending on the input state of the NC axis servo-on signal that switches between NC axis control and spindle control, when it is being input, S
The normal NC axis control is carried out at 33, and when not inputted, the main axis control of the servo motor is carried out at S34.

That is, the NC axis control switching processing section 190
Synchronizes the positioning command position used for control as the NC axis with the rotation command position used for control as the spindle, and performs NC axis processing (positioning processing) and spindle processing (rotation speed command processing) with signals. To switch the positioning command position and the rotation command position and switch the positioning operation by the positioning command and the rotation operation by the spindle command rotation speed to position the NC axis at the commanded position, or It is switched so that the spindle can be rotated by the rotation speed command.

As described above, the NC shaft 204 and the main shaft 804 can be driven by one servo motor 202 by switching the processing for calculating the position command pulse of the servo drive device. For example, the rotary shaft used as the tool positioning shaft is treated as the main shaft for driving the rotary tool. Since the servo drive system uses the same control method when position control is performed as the NC axis and when it is controlled as the main axis, it is possible to smoothly switch from the positioning command to the rotation command, and the cycle time Can be improved.

[0048]

As described above, according to the present invention, in a servomotor for positioning and a numerical control device coupled with a servo drive device for controlling the position of the servomotor, the main shaft engaged with the servomotor is A spindle acceleration / deceleration processing unit that sets an acceleration / deceleration command speed of the spindle according to a preset acceleration / deceleration pattern based on a command rotation speed, and a servo drive device that integrates the acceleration / deceleration command speed and drives the spindle. Since the main shaft can be driven by a synchronous motor such as a servo motor by providing a speed position conversion circuit that converts to a position command value, a motor with the same output as compared to the case of using a conventional induction motor The installation range can be reduced and the machine tool can be downsized. Further, since a higher torque can be output as compared with the conventional spindle, the working application range can be widened. Further, since the servo drive device and the servo motor that drive the NC axis are used, the cost can be reduced and the maintenance is easy. Also,
Since the spindle is rotated by the position control, the position is compensated for the speed fluctuation due to the load at the start of cutting.
It is possible to improve the accuracy at the start of thread cutting.

Further, since the multi-step acceleration / deceleration parameter for setting the acceleration / deceleration pattern in multiple steps is provided, any acceleration / deceleration determined by the multi-step acceleration / deceleration parameter including the acceleration / deceleration pattern almost equal to that of the induction motor is included. The pattern can be realized.

[0050]

Further, the servo motor is NC while the position control is performed.
The servo drive device operates as an NC axis by providing a spindle / NC axis control switching processing unit that drives the axis and the spindle, and switches the positioning operation based on the positioning command to the NC axis and the rotational operation based on the rotation speed command to the spindle. Since the control method is the same when the position control is performed and when the control is performed as the main axis, it is possible to smoothly switch from the positioning command to the rotation command and improve the cycle time.

[Brief description of drawings]

FIG. 1 is a block diagram showing a numerical control device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of multistage acceleration / deceleration in the numerical controller of FIG.

3 is a flowchart relating to multi-step acceleration / deceleration in the numerical controller of FIG.

FIG. 4 is an explanatory diagram of spindle acceleration / deceleration control in the numerical controller of FIG. 1.

FIG. 5 is a block diagram showing a numerical control device according to a second embodiment of the present invention.

6 is an explanatory diagram showing a phase relationship between a motor and a spindle in the numerical controller of FIG.

FIG. 7 is a block diagram showing a numerical control device according to a third embodiment of the present invention.

8 is a flowchart showing an operation of a spindle / NC axis control switching processing unit in the numerical controller of FIG.

FIG. 9 is a block diagram showing a conventional numerical control device.

[Explanation of symbols]

101 numerical control device, 102 machining program, 10
3 analysis processing unit, 104 interpolation processing unit, 105 PLC
Circuit, 106 machine control signal processing unit, 107 memory,
108 parameter setting unit, 109 screen processing unit, 11
0 spindle control unit, 120 data input / output circuit, 130
Analog output circuit, 131 encoder input device, 15
0 speed position conversion circuit, 151 spindle servo parameter, 160 spindle acceleration / deceleration processing unit, 161 multi-stage acceleration / deceleration parameter, 170 spindle phase calculation processing unit, 171 reference position holding unit, 172 reference position initial setting unit, 175 absolute position holding device , 180 NC axis processing section, 190 main axis / NC axis control switching processing section, 201 servo drive device, 2
02 servo motor, 204 NC axis, 205 detector, 801 servo drive device, 802 servo motor,
804 spindle, 805 detector.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-164822 (JP, A) JP-A-1-120607 (JP, A) JP-A-6-266439 (JP, A) JP-A-6- 110553 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G05D 3/00-3/20

Claims (2)

(57) [Claims] 1. A numerical control device comprising a servo motor for positioning and a servo drive device for controlling the position of the servo motor, wherein a reference inclination amount for acceleration / deceleration is determined from a limit rotational speed of a spindle and a basic time constant. , The multi-step acceleration / deceleration parameter set by multiplying the reference tilt amount by the pre-set multi-step tilt magnifications, and the multi-step acceleration / deceleration based on the command rotational speed of the spindle engaged with the servo motor. A spindle acceleration / deceleration processing unit that sets an acceleration / deceleration command speed of the spindle by an acceleration / deceleration pattern set in multiple stages by parameters, and integrates the acceleration / deceleration command speed to obtain a position command value for a servo drive device that drives the spindle. A numerical control device comprising a speed position conversion circuit for conversion. 2. A spindle / NC axis control switching processing unit for driving an NC axis and a spindle while the servo motor is still in position control, and switching between a positioning operation by a positioning command for the NC axis and a rotating operation by a rotation speed command for the spindle. 2. The numerical controller according to claim 1, further comprising: