JP4110959B2 - Spindle synchronous control method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spindle synchronization control method and apparatus, and more particularly to a method and apparatus for synchronously controlling a main spindle motor that drives a main spindle that supports a square workpiece and a sub spindle motor that supports the square workpiece. is there.
[0002]
[Prior art]
In spindle synchronization control for synchronously controlling a main spindle motor that drives a main spindle that holds a workpiece and a guide bush spindle motor (sub-spindle motor) that drives a rotary guide bush that guides the workpiece, the workpiece and the rotary guide A correction amount of the rotational position command of the guide bushing spindle motor is calculated based on a clearance generated between the bushing and the bushing, and a rotational position command obtained by correcting the correction amount with respect to the rotational position command of the main spindle motor is calculated as the guide bushing. There are some which use the rotational position command of the spindle motor. (For example, see Patent Document 1)
[0003]
In addition, when passing a square workpiece between the main spindle and sub spindle, the rotation coordinate value from the reference position of each of the main spindle and sub spindle is detected from the spindle position detector, and the difference between the rotation coordinate values of both is detected. The calculated difference (only the initial value) is divided into N, and the divided difference is added to or subtracted from the main spindle or sub-spindle position command to obtain a reference position for each of the main spindle and the sub-spindle. There is one that delivers the square work by matching the two. (For example, see Patent Document 2)
[0004]
Furthermore, there is a machine that processes a workpiece by gripping the workpiece from both sides with a main spindle and a back spindle (sub spindle) and rotating the workpiece in synchronization with both spindles. (For example, see Patent Document 3)
[0005]
[Patent Document 1]
JP-A-10-34401 (pages 3 to 18, FIGS. 1 to 37)
[Patent Document 2]
Japanese Patent Laid-Open No. 2-109605 (Pages 2 to 3, FIGS. 1 to 4)
[Patent Document 3]
JP-A-7-186007 (2nd to 3rd pages, FIGS. 7 and 8)
[0006]
[Problems to be solved by the invention]
By the way, as shown in FIG. 12, when a square work (for example, a bar work having an octagonal cross section) that is twisted by a predetermined angle with respect to the axis is processed by the machine disclosed in Patent Document 1, a guide bush spindle motor is used. If the main spindle motor is not optimally controlled, the guide bush spindle motor generates heat or stops due to an alarm such as overload.
Similarly, when machining with the machine disclosed in Patent Document 3, unless the back spindle motor is optimally controlled with respect to the main spindle motor, the back spindle motor (sub-spindle motor) generates heat or excessively. It stops with an alarm such as a load.
However, in the above-mentioned patent document, a guide bush main shaft motor or a back surface in the case of processing a square member workpiece twisted by a predetermined angle with respect to the axis line by the machine disclosed in the above-mentioned patent document 1 or the machine disclosed in the above-mentioned patent document 3. No consideration is given to control for preventing heat generation and overload of the spindle motor.
[0007]
This will be described in detail as follows.
The machine (automatic lathe) disclosed in Patent Document 1 has a configuration as shown in FIGS. FIG. 9 is a detailed configuration diagram of the main spindle and the rotary guide bush of the machine shown in FIG.
That is, one long square workpiece 1003 (square workpiece as shown in FIG. 12) is a chuck (not shown) of the main spindle 1004 (the main spindle motor 13a itself forms a spindle stock). Further, it is connected to a pulley 1006 through a timing belt 1007 and supported by a rotary guide bush 1005 driven by a rotary guide bush main shaft motor 13b. Then, the workpiece 1003 is rotated by a rotation command for the main spindle 1004, and is further moved from right to left (moved in the Z-axis direction) to move up and down only in the X-axis direction (tool base 1002). Is held by the machine). At this time, the rotary guide bush 1005 is controlled to rotate in synchronization with the main main shaft 1004.
For example, when the coupling ratio between the rotary guide bush 1005 and the rotary guide bush spindle motor 13b is 1: 1, if the rotary guide bush spindle motor 13b rotates at 1000 rpm, the rotary guide bush 1005 also rotates at 1000 rpm. To do. In general, the rotary guide bushing spindle motor 13b has smaller torque characteristics and output characteristics than the main spindle motor 13a.
[0008]
When machining a square work 1003 with such a machine, for example, on the main spindle 1004 side, as shown in FIG. 10, the chuck 1008 uses a chuck having the same shape as the square work. Similarly, a guide bush having the same shape as the square workpiece 1003 is used on the rotary guide bush 1005 side. Accordingly, when the square workpiece 1003 is twisted as shown in FIG. 12, for example, when the square workpiece cross section M on the main spindle side and the square workpiece cross section G on the rotary guide bush spindle side in FIG. As shown.
Here, when the position (angle) of the main spindle is used as a reference, as shown in FIG. 11, the cross section on the rotary guide bush spindle side is a difference in position due to torsion of the square material workpiece 1003, that is, an angular difference (in FIG. The twist angle on the side is indicated by α). In other words, the spindle motor with the smaller output torque (rotary guide bushing spindle motor 13b in this example) loses to the spindle motor with the larger output torque (main spindle motor 13a in this example). As shown in FIG. 11, the position based on the main shaft motor (main main shaft motor 13a in this example) and the position (feedback position) of the main shaft motor (rotary guide bush main shaft motor 13b in this example) with the smaller output torque are shown. A difference (twist angle: α) occurs.
[0009]
In addition, while the spindle is rotating, there is a difference between the rotational position command from the numerical controller and the actual position (feedback position) of the spindle motor. In addition, the rotary guide bush spindle motor 13b has the above-mentioned twist angle. Therefore, there is a large difference between the rotational position command from the numerical controller and the actual position of the rotary guide bushing spindle motor 13b. Therefore, the rotary guide bushing spindle amplifier passes an excessive current to the rotary guide bushing spindle motor 13b so as to eliminate the difference. As a result, the rotary guide bushing spindle motor 13b generates heat, and the rotary guide bushing spindle motor 13b stops due to an alarm such as overload.
[0010]
Further, when machining the square workpiece 1003 with the machine disclosed in Patent Document 3, the back spindle motor generates heat due to the same phenomenon (operation) as described above, and further, the back spindle motor is overloaded. There was a problem of stopping with an alarm.
[0011]
Note that the control disclosed in Patent Document 2 is a correction that makes the twist angle 0 when the workpiece is twisted when the square workpiece is transferred (correction so that the reference positions of the main spindle and the sub spindle coincide). Since the main spindle or sub spindle is controlled by the main spindle or the sub spindle, the twisted workpiece and the main spindle or the sub spindle will repel each other. Therefore, even if the control disclosed in Patent Document 2 is used, the spindle motor will be excessive. Stopping due to an alarm such as a load cannot be prevented. In addition, the difference (only the initial value) of the rotation coordinate value of the main spindle and the sub spindle detected only when the spindle rotation command is issued (phase alignment) is divided into N and added to or subtracted from the position command of the main spindle or sub spindle. Therefore, compensation for dynamically changing workpiece twist is not possible.
[0012]
[Means for Solving the Problems]
The present invention has been made to solve the above-described problems, and prevents the sub spindle motor from generating heat or being stopped by an alarm such as an overload even when the square workpiece is twisted. An object of the present invention is to provide a spindle synchronous control method and apparatus capable of the same.
Therefore, in the spindle synchronous control method according to the present invention, there is a difference between the output torque of the main spindle motor that drives the main spindle that supports the square workpiece and the output torque of the sub spindle motor that supports the square workpiece, And said Main spindle motor and sub spindle In the spindle synchronous control method in which the motor is driven with the same command, the amount of twist between the main spindle side and the sub spindle side in the square work is detected during the spindle synchronous control operation, and the main amount is detected from the detected twist amount. Calculate the correction amount of the rotational position command for the main spindle motor or sub-spindle motor, and apply this correction amount to the command of the main spindle motor or sub-spindle motor in the direction in which the load current of the motor with the smaller output torque decreases. To add or subtract.
[0013]
The spindle synchronous control method according to the present invention repeatedly executes correction while confirming the twist angle of the square workpiece.
[0014]
Further, the spindle synchronous control method according to the present invention instructs a correction amount multiplied by a predetermined correction magnification to the main spindle motor or the sub spindle motor.
[0015]
The spindle synchronous control method according to the present invention monitors the twist angle and automatically executes the correction when the twist angle exceeds a predetermined value.
[0016]
In the spindle synchronous control method according to the present invention, the torsion angle is obtained on the basis of the position difference between the main spindle and the sub spindle motor that supports the workpiece, or the current value of the sub spindle motor.
[0017]
Further, in the spindle synchronous control device according to the present invention, there is a difference between the output torque of the main spindle motor that drives the main spindle that supports the square workpiece and the output torque of the sub spindle motor that supports the square workpiece, and Said Main spindle motor and sub spindle In the spindle synchronous control device for driving the motor with the same command, a workpiece twist amount detecting means for detecting a twist amount between the main spindle side and the sub spindle side in the square workpiece during the spindle synchronous control operation, and the workpiece twist The correction amount of the rotational position command for the main spindle motor or the sub spindle motor is calculated from the torsion amount detected by the amount detection means, and this correction amount is set in the direction in which the load current of the motor with the smaller output torque decreases. And a correction execution means for adding to or subtracting from the command of the main spindle motor or the sub spindle motor.
[0018]
In the spindle synchronous control device according to the present invention, the correction execution means repeatedly executes correction while checking the torsion angle of the square workpiece.
[0019]
In the spindle synchronous control apparatus according to the present invention, the correction execution means commands a correction amount multiplied by a predetermined correction magnification to the main spindle motor or the sub spindle motor.
[0020]
In the spindle synchronous control device according to the present invention, the correction execution means monitors the twist angle, and automatically executes the correction when the twist angle exceeds a predetermined value.
[0021]
In the spindle synchronous control device according to the present invention, the torsion angle is obtained based on the difference in position between the main spindle and the sub spindle motor that supports the workpiece, or the current value of the sub spindle motor.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to FIGS.
FIG. 1 is a block diagram showing a main part of a numerical controller having a spindle synchronous control device according to the first embodiment, and controls the machine shown in FIGS. FIG. 2 is a diagram showing a machining program for controlling rotation / stop of the main spindle motor, etc. FIG. 3 is a flowchart showing a procedure for correcting a rotational position command for the rotary guide bush spindle motor when a square workpiece is twisted. 4 is a graph showing the relationship between the droop amount of the main spindle motor and the rotary guide bush spindle motor and the droop amount when the square workpiece is twisted, and FIG. 5 is the rotational position with respect to the rotary guide bush spindle motor when the square workpiece is twisted. FIG. 6 is a diagram showing an example of a command correction pattern and a current change example of a rotary guide bush spindle motor, FIG. 6 is a diagram showing an example of an interface between a machine control signal processing unit and a ladder circuit, and FIG. 7 is a case where a square workpiece is twisted The torque (force) of the rotary guide bushing spindle motor and the force due to elastic deformation of the square workpiece Is a diagram showing the engagement.
[0023]
In FIG. 1, 1 is a numerical control device, 2 is a machining program, 3 is a machining program analysis processing unit, 4 is an interpolation processing unit, 5 is a ladder circuit, 6 is a machine control signal processing unit, 7 is a memory, and 8 is a parameter setting. , 9 is a screen display unit, 10a is a main spindle axis control unit (hereinafter referred to as main axis control unit), 10b is a rotary guide bush spindle control unit (hereinafter referred to as rotary guide bush axis control unit), and 11 is A data input / output circuit, 12a is a main spindle main shaft amplifier (hereinafter referred to as main main shaft amplifier), 12b is a rotary guide bush main shaft main amplifier (hereinafter referred to as rotary guide bush main shaft amplifier), and 13a is a main main spindle motor (hereinafter referred to as main shaft amplifier). , 13b is a main shaft motor (sub main shaft motor) of the rotary guide bush main shaft (hereinafter referred to as the rotor). Guide that bush spindle motor), 40 a work torsional amount detecting means, 41 is a correction executing means.
The rotary guide bushing spindle motor 13b has smaller torque characteristics and output characteristics than the main spindle motor 13a.
[0024]
Further, in the machining program 2 for the part that drives the main spindle motor 13a shown in FIG. 2, the command M3 is a rotation start command for the main spindle motor 13a, and the command S1 is a rotation speed command for the main spindle motor 13a (in this case, 1000 rpm). The command M5 represents a rotation stop command for the main spindle motor 13a.
[0025]
Next, the operation of the numerical controller shown in FIG. 1 will be described.
First, the parameter setting unit 8 sets parameters in advance so that the main spindle motor 13a and the rotary guide bush spindle motor 13b always rotate in synchronization. The machining program 2 read from a tape reader or the like is stored in the memory 7. When the machining program 2 is executed, the machining program analysis processing unit 3 reads the machining program 2 from the memory 7 one block at a time. The read machining program 2 is processed by the machining program analysis processing unit 3.
[0026]
The machining program example in FIG. 2 will be described. First, the machining program analysis processing unit 3 reads the rotation start command M3 and the rotation speed command S1 of the main spindle motor 13a from the memory 7. These commands read out next are determined to be commands to be notified to the ladder circuit 5 describing the control of the machine control signal such as cutting oil on / off in the machining program analysis processing unit 3, and the machine control signal processing is performed. The analysis result is notified to the unit 6. The machine control signal processing unit 6 converts the notified analysis result into a machine control signal and outputs the machine control signal to the ladder circuit 5. The ladder circuit 5 determines whether the main spindle motor 13a is in a rotatable state, and then outputs a rotation start signal to the machine control signal processing unit 6 if the main spindle motor 13a is in a rotatable state.
[0027]
The rotation start signal and rotation speed data input to the machine control signal processing unit 6 are passed to the interpolation processing unit 4. The interpolation processing unit 4 converts the rotational speed data into a rotational position command for the main spindle motor 13a. Further, since the main spindle motor 13a and the rotary guide bush spindle motor 13b are set in advance by parameters and the like so that they are always controlled synchronously, the rotational speed data of the main spindle motor 13a is also applied to the rotary guide bush spindle motor 13b. To calculate the rotational position command of the rotary guide bushing spindle motor 13b. The rotational position commands of the main main shaft motor 13a and the rotary rotary guide bush main shaft motor 13b are output to the main shaft control unit 10a and the rotary guide bush shaft control unit 10b, respectively.
[0028]
These rotational position commands are recalculated in the main shaft control unit 10a and the rotary guide bush shaft control unit 10b to servo position commands per unit time in consideration of acceleration / deceleration according to a pre-specified acceleration / deceleration pattern. It is output to the input / output circuit 11. These servo position commands are transmitted to the main spindle amplifier 12a and the rotary guide bush spindle amplifier 12b via the data input / output circuit 11, respectively.
[0029]
The main main shaft amplifier 12a and the rotary guide bush main shaft amplifier 12b rotate the main main shaft motor 13a and the rotary guide bush main shaft motor 13b while controlling their positions in accordance with the received servo position command. Here, because the acceleration / deceleration patterns of the main shaft control unit 10a corresponding to the main spindle main shaft motor 13a and the rotary guide bush shaft control unit 10b corresponding to the rotary guide bush main shaft motor 13b are adjusted to be the same, The workpiece 1003 chucked on the main spindle 1004 and the rotary guide bush 1005 can rotate synchronously even when the rotational speed is changing.
[0030]
Next, when a machining program command M5 that means rotation stop of the main spindle is executed, the machining program analysis processing unit 3 notifies the machine control signal processing unit 6 of the analysis result, and the machine control signal processing unit 6 executes the ladder circuit. 5 is output. The ladder circuit 5 receives the rotation stop command M5 and turns off the rotation start signal. The machine control signal processing unit 6 detects that the rotation start signal is turned off and notifies the interpolation processing unit 4 of a rotation stop command. In the interpolation processing unit 4, a rotation speed command 0 is commanded to the main shaft control unit 10a and the rotary guide bush shaft control unit 10b.
[0031]
This command is recalculated into a servo position command taking acceleration / deceleration into consideration according to an acceleration / deceleration pattern designated in advance by the main shaft control unit 10a and the rotary guide bush shaft control unit 10b, and is output to the data input / output circuit 11. . The servo position command is transmitted to the main spindle amplifier 12a and the rotary guide bushing spindle amplifier 12b via the data input / output circuit 11. The main spindle amplifier 12a and the rotary guide bush spindle amplifier 12b decelerate and stop the main spindle motor 13a and the rotary guide bush spindle motor 13b in synchronization with each other according to the received command.
[0032]
Next, the correction of the rotational position command for the rotary guide bushing spindle motor 13b when the square work 1003 is twisted as shown in FIG. 12 will be described using the flowchart of FIG.
That is, in step 31, the rotational speed data commanded by the machining program 2 is input via the machine control signal processing unit 6 and passed to the interpolation processing unit 4. The interpolation processing unit 4 converts the rotational speed data into a rotational position command for the main spindle motor 13a. Further, since the main spindle motor 13a and the rotary guide bush spindle motor 13b are set in advance by parameters or the like so that they are always controlled synchronously, the rotational speed data of the main spindle motor 13a is also set for the rotary guide bush spindle motor 13b. The rotational position command of the rotary guide bushing spindle motor 13b is calculated. The rotational position commands of the main spindle motor 13a and the rotary guide bush spindle motor 13b are output to the respective spindle amplifiers 12a and 12b via the main shaft control unit 10a, the rotary guide bush shaft control unit 10b, and the data input / output circuit 11. .
[0033]
In step 32, the work twist amount detection means 40 detects the droop amount of the main spindle motor 13a and the rotary guide bush spindle motor 13b. The droop amount indicates the difference between the rotational position command commanded to the spindle amplifier by the numerical controller 1 and the actual position (feedback position) of the spindle motor, and is calculated by the spindle amplifiers 12a and 12b. Therefore, the workpiece twist amount detection means 40 acquires the droop amount calculated by the spindle amplifiers 12a and 12b via the data input / output circuit 11 and the axis controllers 10a and 10b. Further, since a follow-up delay occurs when the spindle motor rotates, a normal droop occurs during rotation of the spindle motor, but when the main spindle motor 13a and the rotary guide bush spindle motor 13b are controlled at the same rotational speed, As shown in FIG. 4A, the droop amount of the main spindle motor 13a and the rotary guide bush spindle motor 13b is the same (droop amount A = droop amount B). Accordingly, when the difference in the droop amount between the main spindle motor 13a and the rotary guide bush spindle motor 13b is calculated, it is normally “0”.
[0034]
However, when the supported square work is twisted as shown in FIG. 12, the rotary guide bushing spindle motor 13b is shifted by the twist of the square work (in the example of FIG. 11, it is shifted by the twist angle α). 4) As shown in FIG. 4B, there is a difference in the droop amount between the main spindle motor 13a and the rotary guide bush spindle motor 13b.
Accordingly, if the droop amount of the main spindle motor 13a is subtracted from the droop amount of the rotary guide bushing spindle motor 13b, the droop amount corresponding to the twist angle α (the droop amount corresponding to the twist angle α = the droop amount B′−the droop amount A) is obtained. Obtainable. Here, the droop amount is a value having directionality, and specifically, the forward rotation direction is a plus sign and the reverse rotation direction is a minus sign. Therefore, as shown in FIG. 4C, when the rotation is in the reverse direction, the droop amount corresponding to the twist angle α is negative. By determining this sign, it can be determined whether the correction for the rotary guide bushing spindle motor 13b calculated in the next step 33 is applied in the forward direction or the reverse direction.
As described above, whether or not the droop difference (twist angle) between the main spindle motor and the guide bush spindle motor exceeds the preset value is constantly monitored, so the torsion angle can be applied both during workpiece insertion and during machining (work extrusion). If the value exceeds the predetermined value, correction is started.
[0035]
The workpiece twist amount detection means 40 compares the detected droop amount corresponding to the twist angle α with a predetermined value (predetermined twist angle: unit in degrees). The default value of the twist angle is a register that is an interface between the ladder circuit 5 and the machine control signal processor 6 as shown in FIG. 6 (“R401” and “R402” in FIG. 6 indicate register numbers). Further, since the value is set in the ladder circuit 5, the workpiece twist amount detecting means 40 reads the value via the machine control signal processing unit 6.
The correction magnification is also set in the register (R402). This will be described later.
This determination is performed as follows. That is, since the unit of the droop amount of the spindle motor that is actually detected is the number of pulses per rotation (for example, 4096 pulses / 1 rotation), first, this value is converted into an angle by equation (1).
Twist angle α (°) = Drop amount corresponding to twist angle α × 360/4096
The workpiece twist amount detection means 40 compares the twist angle α with a predetermined twist angle value. If the twist angle is equal to or smaller than the default value, the process is terminated. If the twist angle exceeds the predetermined value, the process proceeds to step 33.
[0036]
In step 33, in response to the notification from the work twist amount detecting means 40, the correction execution means 41 reads the twist angle α calculated by the work twist amount detecting means 40 in step 32, and the ladder circuit 5 reads the register (R402). The set correction magnification value is read via the machine control signal processing unit 6. From these values, the correction execution means 41 calculates a correction amount. The correction amount is calculated as follows.
Correction amount (pulse) = calculated twist angle α × correction magnification × 4096/360
[0037]
Next, at step 34, the correction execution means 41 determines the sign of the correction amount, and adds it if the sign is positive to the rotational position command for the rotary guide bushing spindle motor 13b, and subtracts if the sign is negative. Then, the rotational position command, which is the calculation result, is output to the rotary guide bush spindle amplifier 12b via the shaft control unit 10b and the data input / output circuit 11. Next, the process returns to step 32, and the process is repeated until the detected twist angle α becomes smaller than the predetermined twist angle value.
[0038]
The reason for repeating the process is as follows.
That is, when the square work 1003 is twisted and the state of the rotary guide bush spindle is as shown in FIG. 7 (when the square is twisted in the D direction), the position A based on the main spindle and the rotary guide bush spindle In the actual position (feedback position) B, there is a difference in the torsion of the square bar.
This is presumed to be in the following state. That is, the rotary guide bushing spindle amplifier 12b causes an excessive current to flow through the rotary guide bushing spindle motor 13b so as to eliminate the difference, and generates a large torque in the rotary guide bushing spindle motor 13b. Accordingly, in the example of FIG. 7, torque (force) in the C direction is relatively applied to the square bar workpiece 1003. For this reason, the square member workpiece 1003 is elastically deformed, and the place where the torque of the rotary guide bushing spindle motor 13b and the reaction force (force in the D direction) due to the elastic deformation of the square member workpiece 1003 are balanced is detected as the twist angle α. When a command obtained by adding or subtracting the detected torsion angle to the rotational position command is output to the rotary guide bush spindle motor 13b, the position A based on the main spindle should match the actual position B of the guide bush spindle. However, when the torque of the rotary guide bushing spindle motor 13b decreases due to the correction, the force (force in the D direction) due to the elastic deformation of the square workpiece 1003 actually pushes the rotary guide bush 1005 again. Therefore, a difference occurs again between the position A with respect to the main spindle and the actual position B of the guide bush spindle. Therefore, it is necessary to correct the rotational position command to the rotary guide bushing spindle motor 13b again. For this reason, the correction is repeated.
[0039]
The correction magnification is for increasing the correction efficiency. Specifically, the correction amount (pulse) for the rotary guide bushing spindle motor 13b is calculated by multiplying the correction amount by the value specified by the correction magnification at the time of correction. As a result, the number of corrections can be reduced and the correction time can be shortened. However, since the appropriate value of the correction magnification varies depending on the machine, the workpiece material / diameter, etc., it is necessary to determine the value experimentally.
[0040]
FIG. 5 shows the current value behavior of the rotary guide bushing spindle motor 13b when correction is applied to the rotary guide bushing spindle motor 13b. In this example, the current value of the rotary guide bushing spindle motor 13b increases from I1 to I2 due to torsion of the square workpiece 1003. After the correction starts at time t2, the current value of the rotary guide bushing spindle motor 13b changes from I2 after three corrections. It turns out that it has reduced to I1 in the state without the twist of a square workpiece.
[0041]
In the first embodiment, the rotary guide bushing spindle motor 13b is smaller in torque characteristics and output characteristics than the main spindle motor 13a, so that the rotary guide bushing spindle motor 13b is corrected. However, when the main spindle motor 13a is smaller in torque characteristics and output characteristics than the rotary guide bushing spindle motor 13b, the main spindle motor 13a generates heat, and therefore the main spindle motor 13a is corrected. Make a call.
[0042]
Embodiment 2. FIG.
The synchronization between the main spindle motor 13a and the rotary guide bush spindle motor 13b that drives the rotary guide bush 1005 has been described above. Instead of the rotary guide bush spindle motor 13b that drives the rotary guide bush 1005, the back spindle 1008 is used as a square member. The same effect can be obtained even with a back spindle motor that supports the workpiece 1003 and rotates in synchronization with the main spindle. Specifically, as shown in FIG. 13, even when the square work 1003 is connected between the main spindle 1004 and the rear spindle 1008 and the square work 1003 is cut with a holder and a tool 1010 attached to the turret 1009, Even when the square workpiece 1003 is twisted and the actual position of the back spindle 1008 is shifted from the position with respect to the main spindle, if the back spindle 1008 or the main spindle 1004 is corrected as described above, the back spindle 1008 is corrected. Can continue cutting without alarm.
[0043]
In the first embodiment, the twist of the square workpiece 1003 is obtained from the droop difference between the main spindle motor 13a and the rotary guide bush spindle motor 13b. If there is a twist, the current value of the rotary guide bush spindle motor 13b is Therefore, the amount of twist of the square workpiece 1003 can be detected by measuring the current value of the rotary guide bushing spindle motor 13b.
[0044]
【The invention's effect】
As described above, according to the present invention, even when the square workpiece is twisted, an excessive current does not flow to the sub spindle motor, and the sub spindle motor generates heat or an alarm such as an overload occurs. There is no stopping.
[Brief description of the drawings]
FIG. 1 is a principal block diagram of a numerical controller having a spindle synchronous control device according to Embodiment 1 of the present invention;
FIG. 2 is a diagram showing a machining program for a main part for controlling rotation / stop of the main spindle motor and the like according to the first embodiment of the present invention.
FIG. 3 is a flowchart showing a procedure for detecting a twist amount of a square workpiece and correcting a rotational position command according to Embodiment 1 of the present invention;
FIG. 4 is a diagram showing a relationship between the droop amount of the main spindle motor and the rotary guide bush spindle motor and the droop amount when the square workpiece is twisted according to the first embodiment of the present invention.
FIG. 5 is a diagram showing a correction pattern example and a current change example of a rotary guide bushing spindle motor when a rotational position command is corrected according to Embodiment 1 of the present invention;
6 is a diagram showing an example of an interface between a machine control signal processing unit 6 and a ladder circuit 5 according to the first embodiment of the present invention. FIG.
FIG. 7 is a diagram illustrating a relationship between torque (force) of a rotary guide bushing spindle motor and a force due to elastic deformation of a square work when the square work is twisted.
FIG. 8 is a configuration diagram of an automatic lathe which is a type of machine tool according to Embodiment 1 of the present invention.
9 is a detailed configuration diagram of the main spindle and the rotary guide bush shown in FIG.
FIG. 10 is an explanatory diagram when a square bar workpiece is supported by a chuck.
FIG. 11 is a diagram illustrating the positional relationship between the main spindle side and the guide bush side when a square work is twisted.
FIG. 12 is an image view of a twisted square workpiece.
FIG. 13 is a view showing a machine that supports a square bar workpiece with a back main shaft and processes (cuts) the square bar workpiece while rotating in synchronization with the main main shaft.
[Explanation of symbols]
4 Interpolation processing unit, 40 work twist amount detection means, 41 correction execution means, 5 ladder circuit, 6 machine control signal processing unit, 7 memory, 13a main spindle motor, 13b rotary guide bush spindle motor, 1003 workpiece, 1004 main spindle, 1005 Rotary guide bush.

Claims (10)

There is a difference between the output torque of the main spindle motor that drives the main spindle that supports the square workpiece and the output torque of the sub spindle motor that supports the square workpiece, and the same command is used for the main spindle motor and the sub spindle motor. In the spindle synchronous control method driven by the main spindle motor or the sub-spindle, the twist amount between the main spindle side and the sub spindle side in the square work is detected during the spindle synchronous control operation. Calculate the correction amount of the rotational position command for the main shaft motor, and add or subtract this correction amount to the main main shaft motor or sub main shaft motor command in the direction in which the load current of the motor with the smaller output torque decreases. A spindle synchronous control method characterized by:   2. The spindle synchronous control method according to claim 1, wherein the correction is repeatedly executed while checking the twist angle of the square workpiece.   The spindle synchronous control method according to claim 1 or 2, wherein a correction amount multiplied by a predetermined correction magnification is commanded to the main spindle motor or the sub spindle motor.   The spindle synchronous control method according to any one of claims 1 to 3, wherein the twist angle is monitored, and the correction is automatically executed when the twist angle exceeds a predetermined value. .   The said torsion angle is calculated | required based on the difference of the position of the main spindle and the sub spindle motor which supports a workpiece | work, or the electric current value of a sub spindle motor. Spindle synchronous control method. There is a difference between the output torque of the main spindle motor that drives the main spindle that supports the square workpiece and the output torque of the sub spindle motor that supports the square workpiece, and the same command is used for the main spindle motor and the sub spindle motor. In the spindle synchronous control device driven by the workpiece, during the spindle synchronous control operation, the workpiece twist amount detection means for detecting the twist amount between the main spindle side and the sub spindle side in the square workpiece, and the workpiece twist amount detection means The rotation amount command correction amount for the main spindle motor or sub-spindle motor is calculated from the detected twist amount, and the correction amount is calculated in the direction in which the load current of the motor having the smaller output torque decreases. A spindle synchronous control device comprising correction execution means for adding to or subtracting from a command of a motor or a sub spindle motor.   7. The spindle synchronous control device according to claim 6, wherein the correction execution means repeatedly executes correction while confirming a twist angle of a square workpiece.   The spindle according to claim 6 or 7, wherein the correction execution means commands a correction amount multiplied by a predetermined correction magnification to the main spindle motor or the sub spindle motor. Synchronous control device.   The correction execution means monitors the twist angle, and automatically executes the correction when the twist angle exceeds a predetermined value. The spindle synchronous control device according to any one of the above.   10. The twist angle is obtained based on a difference in position between a main spindle and a sub spindle motor that supports a workpiece, or a current value of the sub spindle motor. Spindle synchronous control device.

Images