JPS6036604B2 - Machine tool spindle control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spindle control device for a machine tool, which is used for positioning and controlling the spindle of a machine tool at a predetermined rotation angle position.

In a machine tool having a tool exchange function, for example, a machine tool called a machining center, when a tool is mounted on a spindle from a tool magazine, the key product of the tool and the key of the spindle must match.

For this reason, it is necessary to position the rotational angular position of the main wisteria at a predetermined angular position. Generally, this operation is called a main axis orientation (hereinafter abbreviated as ORI) operation. Conventional machine tool spindle control devices include a cam on the spindle, a recess in the ORI position of this cam, and
ORI positioning was performed by hydraulically inserting a dowel pin into this recess in response to an I operation signal.

However, with this structure, the rotation of the main shaft is abruptly stopped, which causes a large mechanical shock, and the strength of the cam and dowel pin must be increased.
This had the disadvantage that the mechanism was complicated and large. In order to eliminate such drawbacks, the present applicant previously proposed the following spindle control device for a machine tool.

This device is equipped with two control systems, a speed control system and a position control system, and the rotation of the spindle is controlled by the speed control system during cutting, and by the position control system during ORI operation, especially when switching to the position control system. The ORI operation is performed after reducing the rotational energy of the main shaft. However, such a spindle control device uses a resolver that converts the rotation angle of the spindle into an electrical signal as a position detector.

When using a position detector consisting of a resolver, when mechanically connecting the resolver to the main shaft with a reduction ratio of 1:1 without backlash, it is necessary to use gears or a timing belt, and these connection mechanisms There is a drawback that space must be provided in the spindle mechanism. Furthermore, recently, in order to improve the machining accuracy of machine tools, methods have been introduced in which a measuring device is attached to the spindle to measure the machining accuracy of the workpiece and to correct the center position of the spindle.

In this measurement, it is necessary to position and control the rotation angle position of the main shaft at four points, 90o, 180o, and 270o, with the ORI position as a reference. This four-point positioning control is
Although it is difficult to realize a conventional mechanical type because of its complicated mechanism, it is possible to realize it with a spindle control device using a resolver, which was proposed earlier by the applicant. However, the main spindle control device using a resolver has the drawback that a space for a continuous mechanism must be provided in the main spindle mechanism, as described above. The object of the present invention is to enable a position detector to be directly connected to the main axis of a machine tool;
To provide a spindle control device for a machine tool that does not require extra space for installing a position detector and can position and control the spindle at a plurality of points including the ORI position.

FIG. 1 shows the characteristics of the spindle positioning voltage signal E, which is the output of the position detector used in the present invention.

As shown in the figure, when the rotation angle of the spindle changes, the spindle positioning voltage signal E changes in the form of a trapezoidal wave with plus and minus polarities.
Points S1, S2, etc. where the position control system becomes stable as the
...and unstable points AS1, AS2, ...
・The voltage signal E becomes zero. Stable point SI, S2
, . . . If the main shaft ORI position or other position is selected, stable points S1, S2, . . . occur every time the rotation angle a of the main shaft changes by 360°. In this way, for example, the rotation angle 0 of the main shaft is the stable point SI and the unstable point A.
If the control system is at 8(P) between the SI and the RO
When the I operation is performed, the main shaft is moved to a stable point SI and then stopped. In FIG. 1, the direction in which the main shaft is moved during the ORI operation by the rotation angle 8 is indicated by an arrow.
FIG. 2 shows an embodiment of a spindle control device for a machine tool according to the present invention.

In the figure, 1 is a speed command section, 2 is a means for switching between the speed control system and the position control system, 3 is a speed control section, 4 is a spindle mechanism, and 5 is a speed control section.
is the position control section. The speed command unit 1 includes a digital-to-analog converter D/ which converts the digital speed command Ns from digital to analog and outputs an analog speed command voltage signal E.
It is configured with A.

The switching means 2 receives the speed command voltage signal E from the speed command section 1.
, a first analog switch SWI that controls that the signal from the position control section 5 is applied to the speed control section 3, a second analog switch SW2 that controls that the signal from the position control section 5 is applied to the speed control section 3, and an orientation command. The inverter V inverts the signal ORI to control the second analog switch SW2.

The speed control section 3 includes a detection section DT, a servo amplifier SA that amplifies the output voltage ΔE of the detection section DT, a main shaft motor M driven by the output of the servo amplifier SA, and a main shaft motor M.
A speed voltage signal E connected to the speed voltage signal E and proportional to its rotation speed.
It is configured to include a speed generator TG that outputs TC and supplies it to the detection section DT and the position control section 5.

The main shaft mechanism 4 includes a reducer G that reduces the output of the main shaft motor M.
and a main shaft SP rotated with a reduced output.

The position control unit 5 includes a position detector RD that detects a predetermined rotational angle position of the spindle SP and outputs spindle positioning voltage signals EMs and EMs2, and a spindle positioning voltage signal EMs, EMs2 given from the position detector RD. Spindle position designation of any one of the speed voltage signal ETo given from BMs2 and speed generator TG, orientation command signal ORI, and spindle position designation signals A, B, C, and D that designate the position where the spindle SP should be positioned. It is constituted by a control circuit CC which operates with signals etc. as input and outputs a low speed command voltage signal E2 and a spindle positioning voltage signal E3 to the detection section DT via the second analog switch SW2.

In this device, a speed control system 6 is composed of a speed command section 1, a switching means 2, a speed control section 3, and a spindle mechanism 4. Since the position detector RD is one of the features of the present invention, it will be specifically explained with reference to FIG.

That is, this position detector RD includes a first disc DISI and a second disc DIS2 directly connected to the main shaft hawk P, a first magnetizing body MACI fixed to the first disc DISI, and a second disc DISI. A second magnet generating body MAC2 is fixed to the disc DIS2, and first and second magnetic sensors MS1 and MS2 are fixed to the magnetic body MAC2 by a distance 1 and at the same position in the rotational direction. It is configured with The first and second magnetizing bodies MAC1 and MAG2 are each a pair of magnets MAGI which are magnetized as NS in the thickness direction of the arc-shaped magnetic body.
-1, MAGI-2, MAC2-1, MAG2-2, and these magnets are connected to the first and second disks DIS1, DIS2.
One of the magnets MAGI-1 and MAG2 is N
With the pole facing outward, the other magnet MAGI-2, MAC2
-2 is constructed by fixing each pair at different positions by 180 degrees on the symmetrical disks PISI or DIS2, with the S pole facing outward, and at different positions by 90 degrees between the disks. . In such a position detector RD,
When the first and second disks PIS1 and DIS2 are rotated to change the angle 8, the main shaft positioning is determined by the output voltage of the first and second magnetic sensors MS1 and MS2 as shown in FIG. 4A and B. The voltage signals EMs, EMs2 are generated when the magnetic sensors MS1 and MS2 are connected to the first and second magnetizing bodies MAG, respectively.
1. When it corresponds to the N pole of MAC2, it becomes a positive voltage, and when it corresponds to the S pole, it becomes a negative voltage, and the point where it switches from the N pole to the S pole (that is, the point where it switches from the positive voltage to the negative voltage) P1
, P2 and points P3 and P4 where the S pole is switched to the N pole (that is, the point where the negative voltage is switched to the positive voltage), the spindle positioning voltage signals EMs, EMs2 become the koto voltage. The first and second magnetic sensors MS1 and MS2 are attached to the spindle mechanism 4 so that these points P1, P2, P3, and P4 are predetermined positions where the spindle SP should be positioned. In addition, in order to locate the points P3 and P4, the voltage signals EMs, ,
It is necessary to reverse the gutter properties of EMs2 as shown by the broken line so that points P3 and P4 become stable points. Next, the operation of such a spindle control device will be explained.

First, the case of controlling the speed of the spindle SP will be described.

Digital speed command N3 is connected to digital/analog converter D/
When input to A, an analog speed command voltage signal E is output from this converter D/A. On the other hand, since the orientation command signal ORI is not input during speed control, the signal "0" is applied to the first analog switch SWI, and the first analog switch SWI is turned on. In this state, the signal "1" is applied to the second analog switch SW2 after being inversely converted by the inverter INV, so the second analog switch SW2 is off. Since the first analog switch SWI is in the on state, the analog output voltage E of the digital-to-analog converter D/A is applied to the detection section DT as a speed command voltage signal. The rotational speed of the main shaft motor M that drives the main shaft SP via the reducer G is output as a speed voltage signal ETC proportional to the rotational speed by the speed generator G, and this speed voltage signal ETG is also transmitted to the detection unit DT. supplied to The detection part DT detects the voltage △ of the difference between the speed command voltage signal E and the speed voltage signal ETC.
E is output, and the voltage is amplified by the servo amplifier SA to drive the main shaft motor M. The speed control unit 3 controls the speed so that the speed voltage signal ETG, which is proportional to the rotational speed of the main shaft motor M, matches the speed command voltage signal E. Next, the main axis S
The position control operation of P will be explained.

When the orientation command signal ORI is input, a signal "1" is applied to the first analog switch SWI to turn off the first analog switch SWI, while the orientation command signal ORI is reversely converted through the inverter mV. When the second analog switch SW2 is given as a signal "0", the second analog switch SW2 is turned on. In this state, the control circuit CC receives the spindle positioning voltage signal EMs. from the position detector RD. , EMs2, the speed voltage signal ETC from the speed generator TG, and the orientation command signal OR
I and any one spindle position designation signal A, B, C, D
etc. That is, this control circuit CC is configured to issue a predetermined low speed command voltage signal E2 when the orientation command signal ORI and any one of the spindle position designation signals A, B, C, and D are input. . When this low speed command voltage signal E2 is input to the detection section DT via the second analog switch SW2 which is in the on state, the main shaft motor M moves to low speed rotation. In this way, when the spindle motor M reaches low speed rotation (for example, 6 pm or less), the control circuit CC detects the speed voltage signal ETC corresponding to the low speed rotation, and also detects the spindle positioning voltage signal of the position detector RD. After confirming that EMs,, EMs2 is a voltage suitable for the low speed rotation, the next voltage signal EMs,
, , EMs2 comes, it stops outputting the low-speed command voltage signal E2, converts and amplifies the voltage signals EMs, , EMs2, and outputs them as the spindle positioning voltage signal E3. When the control circuit CC follows the above-mentioned process and the voltage signal is switched from E2 to E3, and the preliminary preparations are completed, the process shifts to literal position control. That is, in the spindle motor M, the output voltage signals EMs, EMs2 of the position detector RD become zero voltage, and the spindle SP receives any one of the spindle position designation signals A, EMs2.
Position control is performed so that the rotation stops when a predetermined rotation angle position is reached by B, C, and D. FIG. 5 shows an example of a specific circuit configuration of the control circuit CC that performs the control operation as described above.

That is, this control circuit CC is a flip-flop circuit FF.
1, FF2, NAND gates NA1, NA2, inverters INVI~mV3, and analog switches SW3~S
W8, comparator COM, amplifiers AI and A2,
It is configured by polarity inverting circuits Z1 and Z2, a diode D, and a variable resistor VR connected as shown in the figure. In this case, comparator COM and NAND gate NA
1 and NA2, an inverter mVI, and flip-flop circuits FF1 and FF2 constitute a counter COU having a start/stop function. control circuit CC
For example, when the orientation command signal ORI and the spindle position designation signal A are input, and this spindle position designation signal A turns the analog switch SW5 on, and the output voltage ETC of the speed generator TG falls below a predetermined value, the comparator The output of COM changes from low level to high level, and the NAND gates NAI, NA2 and inverter mVI
Due to this action, the flip-flop circuits FF1 and FF2 are brought into a state in which they can count pulses (the J and K terminals are at low level and the clear terminal CL is at low level).

In this state, a trapezoidal waveform voltage with positive and negative polarity based on the spindle positioning voltage signal EMs from the magnetic sensor MSI is applied to the clock terminal CP of the flip-flop circuit FFI, and the voltage is applied to the amplifier AI and the analog switch SW5.
, diode D, and inverter INV2.
When it is a pole (EMs, is positive), it is low level, and the S pole (
When EMs is negative), it is applied to a high level. When the voltage signal EMs is applied in such a state that it changes from a negative voltage to a positive voltage, the output level of the inverter V2 changes from a high level to a low level, and this change causes the flip-flop circuit FFI to operate. Similarly, when the voltage signal EMs is applied again in a state where it changes to a negative voltage or a positive voltage, the flip-flop circuit FFI operates again, and at the same time, the flip-flop circuit FF2 operates. As a result, the output Q of the flip-flop circuit FF2 changes from a low level to a high level, the output of the NAND gate NA2 becomes a low level, and the J/K terminals become a low level, thereby causing the counter COU to stop counting. Also, in this state, the output Q of the flip-flop circuit FF2 changes from the low level to the low level, the output of the inverter INV3 changes to the high level, the analog switch SW3 is turned off, and the analog switch SW4 is turned on. Thereafter, even if a voltage from the high level to the low level is further inputted to the clock terminal CP of the flip-flop circuit FFI, the flip-flop circuits FF1 and FF2 do not operate and remain connected in the previous state. Note that when resetting this state, the orientation command signal ORI
All you have to do is turn it off (low level).

Voltage signal EM for spindle positioning from magnetic sensor MSI
When the spindle position designation signal A is input and the analog switch SW5 is turned on, s, in addition to the flip-flop circuit FFI, is sent to the analog switch SW2 side as the output voltage signal E3 of the control circuit CC via the analog switch SW4. This spindle positioning voltage signal E3 (EMs,) output to is applied to the detection section DT.

At this time, the main shaft motor M receives the main shaft positioning voltage signal EM.
Position control is performed so that the rotation stops when s reaches the stable point PI in FIG. 4A. Similarly, for example, when the spindle position designation signal C is input and the analog switch SW7 is turned on by this signal, the spindle positioning voltage signal EMs is output to the facultative inversion circuit ZI as shown by the broken line in FIG. 4A. The polarity is reversed and the analog switch SW7,
It is applied to the detection unit DT side via SW4.

At this time, the main shaft motor M receives a voltage signal E whose polarity is inverted.
Position control is performed so that the rotation stops when Ms, reaches the stable point P3 in FIG. 4A. This operation can be summarized as follows.

That is, the orientation command signal OR is sent to the control circuit CC.
I and any one spindle position designation signal A, B, C, D
Then, the speed voltage signal ETC reduced to a value such that the comparator COM operates is input, and the magnetic sensor MS
When the voltage signal EMs or EMs2, which changes from a negative voltage to a positive voltage, is input twice from I or MS2, the output Q of the flip-flop circuit FF2 becomes low level, which turns off the analog switch SW3.
Analog switch SW4 turns on, and voltage signal E
Ms or EMs2 is amplified by the amplifiers AI and A2, or its polarity is inverted by the polarity inverting circuits Z1 and Z2, and outputted to the analog switch SW2 side as a voltage signal E3 via the analog switch SW4, and sent to any of multiple points. Position control is performed. In the state before moving to this kind of operation,
When the output Q of the flip-flop circuit FF2 is at the /. It is output from

Figures 6 to 6 represent the speed control system (
From period 1), the orientation command signal ORI and any one of the spindle positioning voltage signals A, B, C, 0 are input and the spindle motor M changes from high speed rotation to low speed rotation (period 0), low speed rotation is detected. Magnetic sensor MS
The process (period m) until the voltage signal EMs or EMs2 of I or MG2 is detected, the voltage signal EMs, EMs of the magnetic sensor MSI or MS2 is detected again from the low speed rotation state.
2 is detected (period W), the process in which position control is performed (period V), and the process in which position control is connected (period W).
It shows the operating status of each part, such as period). In the above embodiment, the position control operation is performed when the output of the magnetic sensor MSI or MS2 is input twice, but if the main shaft motor M is normally operated at a not very high rotational speed. is a flip-flop circuit.
The position control operation may be performed in a state where the output of the magnetic sensor MSI or MS2 is inputted once.

Alternatively, when the speed is high and the load is large, three or more flip-flop circuits may be used to perform the position control operation when the output of the magnetic sensor MSI or MS2 is input three or more times. Further, although the control circuit CC has been described for the case where the rotation direction of the main shaft motor M is only in one direction, the circuit can also be configured for two directions, normal rotation and reverse rotation, using a rotation direction command as an input condition.

Furthermore, in the above embodiment, the position detector RD is configured by attaching a set of magnetic generators MAGI or MAG2 to the two discs DIS1 and DIS2, respectively, but both generators are attached to one rotating disc, for example, the disc DISI. It is also possible to configure the magnetic bodies MAGI and MAG2 to be attached in two rows in the same positional relationship.

Alternatively, a set of magnetizers, e.g., magnetizer MAGI, may be attached to one rotating disc, e.g., disc PISI, and such a disc DI
The position detector RD can also be configured by fixing the magnetic sensors MSI and MS2 on the outer periphery of the SI at a distance of 1 and at different positions in the circumferential direction by 900 degrees. Also,
Add one more set of the structure shown in Figure 3 and use three sets, or use three sets on one rotating disk to which one magnet generator is attached.
Three voltage signals EMs. , EMs2, and EMs3, and if an amplifier, a polarity inverting circuit, and an analog switch are added to the control circuit CC accordingly, six-point positioning control can be performed. As explained above, according to the spindle control device for a machine tool according to the present invention, the spindle can be positioned and controlled at a plurality of rotation angle positions.

In particular, according to the present invention, the position detector that detects multiple rotational angle positions of the spindle is composed of a magnetizing body and a magnetic sensor, so the position detector can be directly connected to the spindle, and unnecessary It can be implemented without requiring space for the spindle mechanism. Further, in the present invention, since the control circuit can appropriately select a plurality of spindle positioning voltage signals output from the position detector based on the spindle position designation signal, the spindle can be positioned at a desired position.

[Brief explanation of the drawing]

FIG. 1 is a waveform diagram for explaining the principle of positioning using the spindle positioning voltage signal used in the present invention, FIG. 2 is a block diagram showing an embodiment of the spindle control device according to the present invention, and FIG. FIGS. 4A and 4B are waveform diagrams showing an example of a plurality of spindle positioning voltage signals output from the position detector used in the invention, and FIG. 5 is a perspective view showing an embodiment of the position detector used in the invention. A circuit diagram showing an example of a control circuit used in the present invention, and FIGS. 6A to 6C are waveform diagrams illustrating the operation of this embodiment. 1... Speed command unit, 2... Effective sliding means, 3.
... Speed control section, 4 ... Main shaft mechanism, 5.
...Position control unit, 6...Speed control system, 7
...Position control system, M...Main shaft motor,
SP...Main shaft, RD...Position detector, MA
C1, MAG2... Magnetizing body, MS1, MS2.
...Magnetic sensor, CC...Control circuit. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. The speed control system 6 includes a speed control system 6, a position control system 7, and a switching means 2 for switching between the two control systems, and the speed control system 6 includes a speed command section 1 and a speed proportional to the rotational speed of the main shaft motor M. The main shaft motor M is converted into a voltage signal, detected, and fed back to the input side so that the rotation speed of the main shaft motor M becomes a value corresponding to the speed command voltage signal from the speed command section 1. and a main shaft mechanism 4 having a main shaft SP driven by the rotational force of the main shaft motor M, and the position control system 7 detects the rotational angular position of the main shaft SP. The switching means 2 includes a position control section 5 that outputs a control signal to the speed control section 3, the speed control section 3, and the spindle mechanism 4, and the switching means 2 commands the rotational angular position of the spindle SP from the outside. When the orientation command signal is not received, inputting the speed command voltage signal from the speed command section 1 to the speed control section 3;
When receiving the orientation command signal, the switch is configured to input the command signal to the position control section 5 and input a control signal from the position control section 5 to the speed control section 3. In the main shaft control device of the machine, the position control unit 5 detects the rotational angular position of the main shaft SP, and the output voltage becomes zero at a rotational angular position to be positioned at a predetermined position, and the polarity is reversed between positive and negative before and after the angular position. A position detector RD consisting of a combination of a magnetic sensor and a magnet generating body that outputs a plurality of voltage signals for spindle positioning consisting of trapezoidal waveform voltages, and a plurality of voltage signals for spindle positioning from the position detector RD and from the speed control section 3. receives the speed voltage signal, and receives the spindle position designation signal for instructing the position at which the spindle SP should be positioned and the orientation command signal as input signals to the speed control section 3 via the switching means 2, and first outputs the low speed command voltage. Based on the speed voltage signal and the main shaft positioning voltage signal when the rotational speed of the main shaft motor M decreases below a predetermined value by issuing a signal, and based on the main shaft position designation signal instead of the low speed command voltage signal. A spindle control device for a machine tool, comprising a control circuit CC that outputs a selected specific spindle positioning voltage signal.