JP3507938B2 - Linear motor drive method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motor driving method, and more particularly to a linear motor capable of smoothly driving a pair of linear motors arranged on both sides of a slide member used in a machine tool or the like. The present invention relates to a driving method.

[0002]

2. Description of the Related Art In a machine tool, in order to adjust the positions of a work and a tool, a linear motor for moving the support of the work and the tool separately is used. JP-A-6-2
Japanese Patent Publication No. 97286 shows a control method of a linear motor in this case. However, in this case, for example, the position of the Y-axis linear motor is detected, the detection result is input to the control device, and is compared with the Y position that is approached based on the designation of the machine control device to control each linear motor. Is used for.

[0003]

However, in the above-mentioned conventional example, since the pair of linear motors arranged on both sides of the slide member of the machine tool are individually controlled,
It was not easy to match the speed and position between the pair of linear motors. Therefore, there is a problem in that it is not easy to smoothly move the slide member and quickly adjust the position of the slide member.
Therefore, an object of the present invention is to dispose the slide member at both ends of the slide member so as to eliminate the drawbacks of the above-mentioned conventional example and to smoothly move the slide member for position adjustment in a machine tool or the like. It is an object of the present invention to provide a linear motor driving method capable of smoothly controlling the positions of a pair of linear motors.

[0004]

In order to solve the above problems SUMMARY OF THE INVENTION The configuration of the first aspect of the present invention is the driving method for synchronously driving both sides of one of the slide member by a pair of linear motors, the pair of linear Linear motor of one of the motors
The position of the controller is one of a pair of position sensors
Of the linear motor of the pair of linear motors.
The position of the motor is the position of the other of the pair of position sensors.
Position sensor to detect the one from the pair of position sensors.
A mode of applying a feedback signal to the pair of servos corresponding to the pair of linear motors in the drive unit for driving the pair of linear motors can be changed by the switching means according to the movement characteristics of the feed movement of the slide member. A linear motor driving method characterized by the above.

According to the driving method of synchronously driving both sides of one slide member with a pair of linear motors according to the configuration of the first invention, one of the pair of linear motors is used.
The position of the linear motor of one of a pair of position sensors
Of the pair of linear motors detected by the position sensor
The position of the other linear motor is detected by the pair of position sensors.
In the drive unit that detects the other position sensor and drives the pair of linear motors from the pair of position sensors
Since the mode of applying the feedback signal to the pair of servos corresponding to the pair of linear motors can be changed by the switching means according to the movement characteristics of the feed movement of the slide member, the X axis, the Y axis, and the Z axis. Even if there is a difference in the dynamic characteristics of the feed motions of the slide members, the drive units having the same configuration can be adopted. In other words, it is possible to eliminate the need to manufacture a drive unit that is unique to the dynamic characteristics of each slide member.

Further, in the structure of the second invention, in the structure of the first invention, the switching means outputs the output of one of the pair of position sensors in response to a switching signal from the outside. The position is detected by the one position sensor
That said it is possible to input as one of a servo only the feedback signal to drive one of the linear motor is that the output of the other of the position sensor of the pair of position sensors can be input as a feedback signal to each of said pair of servo.

With the configuration of the second invention, in addition to the operation of the configuration of the first invention, the switching means outputs the output of one of the pair of position sensors in response to a switching signal from the outside. The position of the
Since a feedback signal can be input only to one servo that drives the one linear motor that is detected, the output of the other position sensor of the pair of position sensors can be input to each of the pair of servos as a feedback signal. The pair of linear motors can be controlled in association with each other. As a result, the slide member can be moved smoothly.

Further, according to the third aspect of the present invention, in a drive unit for driving a pair of linear motors for one control shaft, the target of the linear motor having the preceding tendency among the pair of linear motors. The deviation is obtained based on the target position command of the pair of linear motors and the feedback signal of the position sensor corresponding to the linear motor having the preceding tendency, and the target given to the linear motor having the delay tendency of the pair of linear motors. The deviation is obtained based on the target position command and the feedback signals of the position sensor corresponding to the linear motor having the delay tendency and the position sensor corresponding to the linear motor having the preceding tendency, and the deviation to the linear motor having the delay tendency is obtained. Depending on the feed speed of the pair of linear motors rather than the target deviation given to the linear motor in the preceding tendency A linear motor driving method is characterized in that so as to pressure.

According to the third aspect of the present invention, in the drive unit for driving the pair of linear motors for one control shaft, the target deviation to the linear motor having the preceding tendency among the pair of linear motors. Is obtained on the basis of the target position command of the pair of linear motors and the feedback signal of the position sensor corresponding to the linear motor having the preceding tendency, and the target deviation given to the linear motor having the delay tendency of the pair of linear mowers is A target to be given to the linear motor having the delay tendency, which is obtained based on the target position command and a feedback signal of the position sensor corresponding to the linear motor having the delay tendency and the position sensor corresponding to the linear motor having the preceding tendency Depending on the feed speed of the pair of linear motors, the deviation from the target deviation given to the preceding linear motors Since so as to increase, it is possible to control so as to follow the linear motor preceding the linear motor in a delayed tendency. Therefore, even if the feed speed changes, the positions of the pair of linear motors for one control shaft can be aligned.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an overview of a machine tool to which the present invention is applied. In the machine tool 1 shown in FIG. 1, in order to adjust the positions of the tool spindle 4 and a table (not shown) for fixing the work, an X shown in FIG.
Axis linear motors 1a, 1b, Y axis linear motors 2a, 2
b and Z-axis linear motors 3a and 3b are provided.

A column 8 is fixed on a bed 9, and an X-axis linear motor 1 is provided between a bed 9 and a saddle 7 which is movable in the X-axis direction along X-axis rails 11a and 11b described later.
a and 1b are provided. Further, Y-axis linear motors 2a and 2b are arranged between a main shaft bed 6 and a saddle 7 which are movable in the Y-axis direction along Y-axis rails 12a and 12b which will be described later, and Z-axis rails 13a to 13c which will be described later. Z-axis linear motors 3a and 3b are arranged between a spindle holding ram 5 and a spindle bed 6 which are movable in the Z-axis direction.
The X-axis rail 11a is arranged on the column 8 and the X-axis rail 11b is arranged on the bed 9. Y-axis rail 1
2a and 12b are arranged on the saddle 7, and the Z-axis rail 13
The spindle beds 6 are provided with a, 13b, and 13c.
The arrow 21 indicates the X-axis direction, and the arrow 22 indicates the Y-axis direction. Furthermore, the Z-axis direction is a direction orthogonal to the X-axis direction and the Y-axis direction.

FIG. 2 shows a block of a control system used in the machine tool shown in FIG. In FIG.
CNC (Computer Numerical Control) 31 is a CPU
31a, memory 31b and interface 31c, and controls the X-axis drive unit 32, the Y-axis drive unit 35, and the Z-axis drive unit 36. X-axis drive unit 3
Reference numeral 2 drives the pair of X-axis linear motors 1a and 1b, and includes a first servo 32a, a second servo 32b, and a distribution switch 32c. The first servo 32a is a CPU
33a, a memory 33b and an interface 33c, and the second servo 32b includes a CPU 34a, a memory 34b and an interface 34c. The linear motor 1
a is a slide member 1c (corresponding to the saddle 7 in FIG. 1).
The linear motor 1b is disposed at one end of the slide member 1c, and the linear motor 1b is disposed at the other end of the slide member 1c. The position sensor 41a is arranged to detect the position of the linear motor 1a, and the position sensor 41b is arranged to detect the position of the linear motor 1b.

The Y-axis drive unit 35 drives the pair of Y-axis linear motors 2a and 2b. The position sensor 42a is arranged to detect the position of the linear motor 2a, while the position sensor 42b is arranged to detect the position of the linear motor 2b. The Z-axis drive unit 36 drives the pair of Z-axis linear motors 3a and 3b. The position sensor 43a is arranged to detect the position of the linear motor 3a, while the position sensor 43b is
Are arranged to detect the position of the linear motor 3b.

FIG. 3 shows three modes of providing the feedback signals input to the X, Y and Z control axes. Figure 3 (a)
Indicates the case of the feedback mode 00. In this case, the distribution switch 32c receives the switching signal 00 and becomes the feedback mode 00, and only the position detection value C1 ′ (t) of the position sensor 41a is fed back to both the first servo 32a and the second servo 32b. . FIG. 3B shows the case of the feedback mode 01. In this case, the distribution switch 32c receives the switching signal 01 and becomes the feedback mode 01, and returns the position detection value C1 ′ (t) of the position sensor 41a to the first servo 32a, and the position detection value C2 ′ of the position sensor 41b. (t) is fed back to the second servo 32b. FIG. 3C shows the case of the feedback mode 10. In this case, the distribution switch 32c receives the switching signal 10 and enters the feedback mode 10, and the position detection value C1 ′ (t) of the position sensor 41a is set to the first servo 32a and the second servo 3a.
2b, and the position detection value C2 'of the position sensor 41b is returned.
(t) is fed back to the second servo 32b.

From the interface (I / F) 31c of the CNC 31 shown in FIG. 2, the target position C1 (t) and the feed speed V1 are supplied to the X, Y, and Z axis drive units 32, 35, and 36, respectively.
(t) is input at a unit minute time Δt interval in FIG. In the contour control, interpolation calculation is performed by the CPU 31a of the CNC 31.
The target position C1 (t) and the feed speed V1 (t) are commanded based on the processed trajectory data. Also,
Feedback mode signals 00, 01, and 10 are selectively input from the CNC 31 to the X-axis drive unit 32 to the first servo 32a, the second servo 32b, and the distribution switch 32c. The feedback mode signal is similarly input to the Y-axis drive unit 35 and the Z-axis drive unit 36.

FIG. 4 shows a flow chart of the operation of the feedback modes 00, 01 and 10, and FIG. 5 shows a continuation of FIG. As an example, the operation of the X-axis drive unit 32 shown in FIG. 2 will be described below. Note that FIG. 6 shows the specific contents of the processing executed by the CPU 34a of the second servo 32b in the drive unit 32 in the target position calculation step of FIG. 4 for each of the three application modes of the feedback signal. The flowcharts of the Y-axis drive unit 35 and the Z-axis drive unit 36 are the same as the flowcharts of the X-axis drive unit 32. (1) Feedback mode 00 Now, with the feedback mode signal 00 specified by the CNC 31, at the time t in FIG.
It is assumed that 1 (t) and the command speed V1 (t) are input to the first servo 32a and the second servo 32b of the X-axis drive unit 32. In response to this command, the first servo 32a receives the input target position C (1) and the feedback signal C1 'from the position sensor 41a.
A target deviation P1 (t) with respect to (t) is calculated, and a servo amplifier (not shown) for the linear motor 1a arranged below the X axis is driven by this deviation output. The first servo 32
Since the operation of a is the same in the following feedback modes 01 and 10, and the control itself is well known, the flowchart of the program executed by the CPU 33a of the first servo 32a is omitted.

On the other hand, the second servo 32b has its CPU 3
4a executes steps 101 to 107 of FIG. In this case, in the calculation of the target deviation P1 (t) in step 105, the feedback signal C1 '(t) from the position sensor 41a for the lower linear motor 1a is used, and the target deviation P1 (t) output in step 106 is used. ) Is less than or equal to the predetermined value e (step 107), the target position C at the next minute time elapse (t + Δt in FIG. 8) is determined in step 120.
Request 1 (t) command to the CNC 31.

(2) Feedback mode 01 Now, with this mode commanded, at time t in FIG. 8, the target position C1 (t) and command speed V1 are sent from the CNC 31.
(t) is the first and second servos 32 of the X-axis drive unit 32
It is assumed that the data is input to a and 32b. First servo 32a
Operates similarly to the feedback mode 00. Second servo 32
In b, the CPU 34a has steps 101 to 10 in FIG.
3, 108 to 111 are executed. In this case, step 1
In calculating the target deviation P2 (t) of 09, the feedback signal C2 ′ from the position sensor 41b for the upper linear motor 1b is used.
Using (t), the target deviation P output in step 110
When 2 (t) becomes less than the predetermined value e (step 111),
At step 120, when the next minute time elapses (see FIG.
Of the target position C1 (t) at time t + Δt)
Request to NC31.

(3) Feedback mode 10 With this mode specified, the target position C1 (t) and the command speed V1 from the CNC 31 at the time t in FIG.
It is assumed that (t) is input to the first servo 32a and the second servo 32b of the X-axis drive unit 32. First servo 3
2a operates similarly to the feedback mode 00. In the second servo 32b, the CPU 34a has steps 101 to 101 in FIG.
103, 112 to 119 are executed. In this case, in step 116, the target deviation P1 (t) and the second servo 3
The target deviation P2 '(t) output by 2b is calculated. That is, first, the target deviation P2 '(t) is calculated by the following equation. P2 ′ (t) = C1 (t) −C2 ′ (t) + αi {P1 (t−
Δt)-(P2 (t-Δt)} In this case, since the positions of the upper and lower linear motors 1a and 1b are the same at the start of control, in step 115, P1 (t-Δt) and P2 (t- Δt)
Are set to zero.

However, at a minute time elapsed time (time t in FIG. 8) other than the control start time, the memory 34b has already been calculated for control at a time minute before the minute time Δt (time t-Δt in FIG. 8). A correction value obtained by multiplying the difference between the target deviations stored in 1 by the weighting coefficient αi is calculated and added. Here, the weighting coefficient αi is added with the coefficient selectively read out in step 112 from the table of FIG. 7 according to the commanded speed V1 (t). For this reason, the target deviation P2 ′ (t) output to the servo amplifier (not shown) for the X-axis upper linear motor 1b is set to a point (t in FIG. 8) that is a minute time before the current point (t in FIG. 8). It is calculated by adding the difference in the movement position between the lower linear motor 1a and the upper linear motor 1b at −Δt). Of course,
As the driving speed of the linear motors 1a, 1b increases, the amount of positional deviation between the upper and lower linear motors 1a, 1b increases, so that the weighting coefficient αi is also increased accordingly as shown in FIG. .

Further, in order to use for the calculation of the target deviation P2 '(t) in step 116 at the next minute time elapse (time t + Δt in FIG. 8), at this time (time t in FIG. 8), Target deviations P1 (t) and P2
(t) and are calculated by the following equation. P1 (t) = C1 (t) -C1 '(t) P2 (t) = C1 (t) -C2' (t) In the next step 117, the target deviation P2 '(t) is the servo of the upper linear mower 1b. The linear mower (for example, the upper linear motor 1b) which is output to the amplifier and tends to be delayed is controlled so as to follow the preceding linear motor (for example, the lower linear motor 1a).

Therefore, the feedback signal on the side of the linear motor, which tends to be delayed, is made to appear to indicate a position which is delayed from the actual detected value, which makes the linear motor on the side of the delayed tendency larger than the actual target deviation. An apparent target value is given, and the slide member 1c having a dynamic motion characteristic that tends to move forward in a tilted direction in the feed direction is controlled to move forward in a non-tilted state. In step 118, the target deviation P1 (calculated in step 116 this time is used for calculation of the target deviation P2 ′ (t) in step 116 at the next minute time lapse time (time t + Δt in FIG. 8). t) and P2 (t) are stored in the memory 34b.

Further, when the target deviation P2 '(t) becomes less than or equal to the predetermined value e in step 119, step 120
Then, the target position C1 (t) at the time when the next minute time has elapsed (time t + Δt in FIG. 8) is requested of the CNC 31. Then, when it is determined in step 121 that the operation off command is given from the CNC 31 to the second servo 32b at the time of completion of positioning, the CPU 34a of the second servo 32b ends the execution of the programs of FIGS. 4 and 5.

With the above construction, in X-axis drive,
From the position sensors 41a, 41b corresponding to the pair of linear motors 1a, 1b to the pair of linear motors 1a, 1b.
The distribution switching device 32c as switching means determines the form of applying the feedback signal to the pair of servos 32a and 32b corresponding to b according to the motion characteristics of the feed motion of the slide member 1c.
The drive units 32, 35, and 36 having the same configuration can be used even if there is a difference in the dynamic characteristics in the feed motion of the X-axis, Y-axis, and Z-axis slide members 1c and the like. That is, it is possible to eliminate the need to manufacture a drive unit unique to the dynamic characteristics of each slide member 1c and the like.

Further, the distribution switching device 32c is the CNC 3
In response to the switching signal from the pair 1, the pair of position sensors 41
The output of one of the position sensors a and 41b can be input as a feedback signal to only one servo that drives the linear motor corresponding to the one position sensor, and the other position of the pair of position sensors 41a and 41b can be input. Since the output of the sensor can be input as a feedback signal to each of the pair of servos 32a and 32b, the pair of linear motors 1
It is possible to control a and 1b in association with each other. As a result, the slide member 1c can be moved smoothly.

Further, in the one provided with the drive unit 32 for driving the pair of linear motors 1a and 1b for one control shaft, the target deviation to the linear motor having the preceding tendency among the pair of linear motors 1a and 1b. Is obtained based on the target position command of the pair of linear motors 1a and 1b and the feedback signal of the position sensor corresponding to the linear motor having the preceding tendency, and the pair of linear mowers 1a and 1b is obtained.
The target deviation given to the linear motor having the tendency of delay is based on the target position command and the feedback signal of the position sensor corresponding to the linear motor having the tendency of delay and the position sensor corresponding to the linear motor having the tendency of preceding. The target deviation given to the linear motor having the delay tendency is increased in accordance with the feed speed of the pair of linear motors than the target deviation given to the linear motor having the preceding tendency. A linear motor can be controlled so as to follow the preceding linear motor. Therefore, even if the feed speed changes, the positions of the pair of linear motors 1a and 1b for one control shaft can be aligned.

In the above embodiment, each drive unit 32, 35, 36 is provided with two servo CPUs, but it is also possible to use one CPU.

[0028]

According to the linear motor driving method of the first invention of the present application, even if there is a difference in the dynamic characteristics in the feed motion of the X-axis, Y-axis, and Z-axis slide members, the drive having the same structure is performed. Units can be used. In other words, it is possible to eliminate the need to manufacture a drive unit that is unique to the dynamic characteristics of each slide member. Therefore, in particular, it is possible to improve the accuracy of position adjustment between the work and the tool of the machine tool that employs the linear motor driving method of the present invention. Further, by the linear motor driving method according to the second aspect of the invention, in addition to the effect of the first aspect of the invention, a pair of linear motors can be controlled in association with each other, so that the slide member can be moved more smoothly. You can Therefore, in particular, the accuracy of position adjustment between the work and the tool of the machine tool that employs the linear motor driving method of the present invention can be further improved. Further, according to the linear motor driving method of the third aspect of the present invention, the linear motor having a delay tendency can be controlled so as to follow the preceding linear motor. The linear motor can be smoothly controlled. Therefore, particularly, the position adjustment of the work and the tool of the machine tool adopting the linear motor driving method of the present invention can be further improved.

[Brief description of drawings]

FIG. 1 is a schematic front view of a machine tool to which the present invention is applied.

FIG. 2 is a block diagram of a control system used in the machine tool shown in FIG.

FIG. 3 is an explanatory diagram showing three modes of applying feedback signals input to an X-axis drive unit.

4 is a CPU of the servo 2 in the X-axis drive unit of FIG.
3 is a flowchart showing an outline of processing executed by the.

FIG. 5 is a flowchart showing a continuation of FIG.

FIG. 6 is an explanatory diagram showing the specific contents of the processing executed by the CPU of the servo 2 in the target position calculation step of FIG. 4 for each of the three application modes of the feedback signal.

FIG. 7 is an explanatory diagram of a weighting coefficient table.

FIG. 8 is an explanatory diagram of commanding a target position for each unit micro time.

[Explanation of symbols] 1a, 1b Linear motor 1c slide member 2a, 2b linear motor 3a, 3b linear motor 32 X-axis control unit 32a, 32b servo 32c distribution switch 35 X-axis control unit 36 X-axis control unit 41a, 41b Position sensor 42a, 42b Position sensor 43a, 43b Position sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-297286 (JP, A) JP-A-2-261003 (JP, A) JP-A-5-83970 (JP, A) JP-A-2- 114879 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02P 5/00 101 H02P 7/00 101 B23Q 5/28 B23Q 15/00 G05B 19/18

Claims (3)

(57) [Claims] 1. A driving method for synchronously driving both sides of one slide member with a pair of linear motors, wherein the position of one linear motor of the pair of linear motors
Position is detected by one of the pair of position sensors
And the other linear motor position of the pair of linear motors
Position with the other position sensor of the pair of position sensors
Detected and drive the pair of linear motors from the pair of position sensors.
It is characterized in that the form of applying the feedback signal to the pair of servos corresponding to the pair of linear motors in the moving drive unit can be changed by the switching means in accordance with the motion characteristics of the feed motion of the slide member. Linear motor driving method. 2. Before the switching means detects the position of the output of one position sensor of the pair of position sensors in response to a switching signal from the outside.
The feedback signal can be input to only one servo that drives one linear motor, and the output of the other position sensor of the pair of position sensors can be input to each of the pair of servos as a feedback signal. The linear motor driving method according to claim 1. 3. A drive unit for driving a pair of linear motors for one control shaft, wherein a target deviation to a linear motor having a preceding tendency among the pair of linear motors is the linear motor of the pair of linear motors. Of the target position command and the feedback signal of the position sensor corresponding to the linear motor having the preceding tendency, and the target deviation given to the linear motor having the delaying tendency among the pair of linear motors is Based on the position sensor corresponding to the linear motor having the delay tendency and the feedback signal of the position sensor corresponding to the linear motor having the preceding tendency, a target deviation given to the linear motor having the delayed tendency is set to the preceding tendency. The target deviation given to a certain linear motor is increased according to the feed speed of the pair of linear motors. Characteristic linear motor driving method.