KR830001054B1 - Spindle exact position control device - Google Patents

Abstract

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Description

Spindle exact position control device

1 is a circuit opening diagram illustrating an outline of a main shaft exact position stop control apparatus according to the present invention.

2a and 3a are waveform diagrams according to FIG.

3A to 3F are explanatory diagrams for explaining a position detector, in particular, a proximity switch.

4A to 4D are explanatory diagrams for explaining the operation of the proximity switch.

5 is a detailed circuit diagram of a position deviation signal generating circuit.

6 is a signal time waveform diagram according to the circuit of FIG.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle main position control device, and more particularly, to a control system for controlling a spindle to stop a high degree of accuracy at a fixed position.

It is known that a so-called machine tool having an automatic tool exchange function for automatically exchanging various tools for machining.

Machine tools with this automatic machine change function change tools in the following manner. That is, a magazine holding several tools rotates to take a hollow tool portion of the magazine directly above the spindle mechanism, and then a contracting mechanism holding a sphere tool for replacing with a new tool protrudes forward.

The magazine immediately above the spindle mechanism then descends to receive the tool and to be retracted by the hollow tool portion of the magazine. Since the spindle mechanism contracts to separate the sphere tool from the spindle, the sphere tool moves to the magazine.

The magazine is then rotated so that the desired new tool is positioned in front of the main shaft and the new tool is received and mounted by the main shaft mechanism projecting forward.

Finally, the magazine is lifted away from the spindle to complete the tool change.

In the tool change mechanism of the above type, it is necessary to make the contraction and the fitting portion of the tool smoothly harmonize with each other, and to stop the key by precisely rotating the main shaft at the correct rotation position. In particular, in order for the key to be fitted to the spindle, the tool must come to the position of the key. A smooth fit of the spindle and the tool requires that the spindle be positioned and stopped so that the key and keyway are correctly opposed.

In order to meet the above requirements, a high spindle position accuracy of ± 0.2 to ± 0.2 ° with respect to the rotation angle of the spindle is required.

Conventional automatic tool changing mechanisms are provided with a photoelectric detector or a limiting switch mechanism for detecting the rotational position of the main shaft key so that the main shaft and the tool can be smoothly fitted.

It is equipped to stop the main shaft in the right position by applying mechanical braking which responds to the signal generated from such a mechanism.

Conventional instruments are not only difficult to determine the desired position with a high degree of accuracy because they rely on mechanical pin braking or the like, but also prolong the use of the stop mechanisms. This wear, in particular the wear of the brake shoes or pins, makes it difficult to gradually stop the spindle in a predetermined position over time, and as a result, automatic change of tools cannot occur smoothly. To avoid this situation, troublesome maintenance checks are required.

Stopping the spindle precisely at a predetermined rotational position is also important during tool replacement or tool withdrawal in boring operations, and is also important when attaching a square workpiece to a spindle such as a lathe.

In the former case, the workpiece is wounded. In the latter case, a situation arises in which the workpiece can not be mounted or removed.

It is impossible to stop the main shaft precisely in the above position with the above-described point, which is impossible with the conventional mechanism, and the operability and the workability are also reduced.

Accordingly, it is an object of the present invention to provide a control circuit for a main shaft position control device through a purely electric method so that the main shaft can be stopped at a predetermined position with high accuracy, avoiding the use of mechanical braking or the like.

Another object of the present invention is to provide a control circuit for the spindle control device so that the spindle can stop at a predetermined position within a short time without the occurrence of overshoot and hunting. A control circuit for a control device, and a control circuit for a main shaft exact position control device which stops the main shaft in position using roughly the position deviation voltage and the accurate position deviation voltage generated in the above-mentioned proximity switch.

Various aspects and advantages of the invention will be apparent from the following description taken in conjunction with the drawings.

1 is a circuit for explaining the outline of the main axis fixed position stop control apparatus according to the present invention, in which the speed command circuit 1 for generating the speed command signal CV and the positive position stop (orientation) command signal ORCM are generated. The position stop command circuit 2 is provided. Reference numeral 3 denotes a speed control circuit, which includes an adder 3a, a phase compensating circuit 3b, a voltage phase converter 3c and a thyristor circuit 3d. The adder 3a outputs the difference voltage (speed deviation) between the command speed CV and the actual speed AV and the difference voltage between the position deviation signal RPD and the actual speed signal AV during speed control. The phase compensating circuit 3b compensates for the phase by advancing or retarding the phase of the adder output voltage. Reference numeral 3c is a voltage-to-phase converter that controls the firing angles of the respective dilisters in the thyristor circuit 3d in accordance with the output voltage of the phase compensation circuit 3b.

The thyristor circuit 3d operates to control the firing angles of the respective thyristors to change the voltage value applied to the DC motor and to adjust the motor rotation speed. When the motor 4 rotates, the tachometer 5 generates a voltage according to the motor speed. 6, the spindle mechanism 7 is a spindle, 8 is a tool, and 9 is a gear (timing belt) which transmits the rotational motion of the DC motor 4 to the spindle 7. The proximity switch 10 (position fencing sensor) is composed of a magnet 10a, a sensor portion 10b and an electric circuit 10c as shown in FIG.

Hereinafter, the position detection sensor will be described in detail.

3 (a) and 3 (b) are diagrams of the magnet 10a attached to the main shaft 7. The magnet 10a creates the main shaft 7 at a rotation angle position that can be stopped at a predetermined position of the main shaft.

The magnet body 10a at the third (c) ° degree shows the magnetic field strength of the permanent magnets 10a "and 10a" 'in 10a' from the S pole to the N pole in the rotational direction of the main axis, that is, the arrow direction. The magnets 10a "and 10" to be changed are attached.

The sensor portion 10b is mounted in a mechanically fixed position to face the magnet body 1a, and includes three saturation repeaters SRA ₁ , SRA ₂ , which are provided in 10b 'in FIG. 3 (c). SRA ₃ is arranged in parallel in the direction of spindle rotation.

Each saturation repeater SRA ₁ (i = 1, 2, 3) has coils L ₁ and L ₂ wound around the core CR as shown in FIG. 3 (d).

The coils L ₁ and L ₂ wound around each core are wound to have opposite polarities, and a high frequency signal is applied to the common terminal TA to output signals to terminals TB and TC of each coil according to the position of the magnet body 10a. Let's do it.

Fig. 3 (e) is a voltage waveform diagram showing the saturated saturators SRA ₁ (i = 1, 2, when the magnet body 10a and the sensor portion 10b are installed in the positional relationship shown in Fig. 3c). This is the voltage waveform output from 3). In particular, DV _1, DV ₂ , DV ₃ represent the voltage waveforms between terminals TB, TC of each saturated riacta SRA ₁ , SRA ₂ , SRA ₃ . Each of these waveforms has a zero Volt value when the centerline of the corresponding saturated riacta SRA ₁ (i = 1, 2, 3) is temporary with the centerline of the magnet body 10a. The waveform appears as a positive and negative voltage crossed above and below the zero Volt level.

The voltage waveform ASV is the sum of the voltages DV ₁ and DV ₃ , which will later be called the detection voltage along with DV ₂ .

The electrical circuit 10c for one saturation repeater SRA is shown in Figure 3 (f). The pulse oscillator OSC, isolation transformer ITB, half-wave rectifiers HWR ₁ and HWR ₂ , which generate a high frequency pulse signal HFP of 100 KHz, are included in this circuit. do. As a result, the output voltage DV ₁ (i = 1, 2, 3) in the third diagram (e) is output between the circuit terminals a and b (the third (f) diagram) of each saturated rigger, and the output voltage is The magnetic field strength changes in proportion to the magnetic field and Hext, depending on the position of the magnet body 10a.

The operation of the voltage waveform DV ₁ will be described with reference to FIG. 4 together with the repeater SRA ₁ on the right side of FIG. 3 (c).

When the magnetic body 10a is far from the saturation limiter SRA ₁ such that the external magnetic field acting on the riacta SRA ₁ has a zero value, the high frequency pulse signal HFP is shown in Fig. 4 (a). It operates around the zero of the BH curve. As a result, the number of magnetic flux lines cutting the coils L ₁ and L ₂ is changed so that the output voltages of the terminals TB and TC are not only the same in size, but also the 180 ° phase is changed. Since this voltage is rectified by each half-wave rectifier HWR ₁ and HWR ₂ , it is important that the voltage becomes zero since the potentials between the terminals a and b are the same. Now when the magnet body 10a approaches the unsaturated Riacta SRA ₁ , the external magnetic field Hext begins to act on the Riacta SRA ₁ . When the magnetic field generated by the high frequency pulse signal HFP is marked as he, the magnetic field according to he-Hext cuts the coil L ₁ and the magnetic field according to he + Hext cuts the coil L ₂ .

If this is indicated by the BH curve, the high-frequency pulse signal HHP operates around -Hext for coil L ₁ (figure 4 (c)) and + Hext for coil L ₂ (figure 4 (d) ) Works. Therefore, the sonic flux that links with the coil L ₁ causes core saturation and less variation (Fig. 4 (c)).

On the other hand, the negative magnetic flux that bridges the coil L ₂ does not cause saturation and generates a larger amount of change (Fig. 4 (d)).

(N은 권선수)로 된다는 관점에서 볼때 단자 b에서의 전위는 단자 a에서의 전위보다 더 높게 되며, 단자들 사이의 전위차를 증가시킨다. 이 전위는 자석체(10a)가 계속해서 회전할 때 제3(e)도의 곡선 DV₁에 의해 보여진 것과 같이 변한다. 이상이 위치 검출기(10)의 개요이다.Induced voltage e

In terms of (N is the number of turns), the potential at the terminal b becomes higher than the potential at the terminal a, increasing the potential difference between the terminals. This potential changes as shown by the curve DV ₁ in the third (e) degree as the magnet body 10a continues to rotate. The above is the outline | summary of the position detector 10. FIG.

Returning to FIG. 1, the positive position control circuit indicated by the number 11 outputs the position deviation signal RPD and the orientation completion signal ORDEN according to the position deviation, the signal generation circuit 11a, and the exact position stop command circuit 2 It consists of a loop switch circuit 11b which drives the loop switch switch 12 which is based on the position command output from the ().

The operation of the position deviation signal generating circuit 11a will be described below with respect to the actual structure of the circuit in relation to the waveform of FIG. 2 (a).

The position deviation signal generating circuit 11a uses the fencing voltage DV ₂ corresponding to the saturated riacta SRA ₂ located at the center of the third (c) (this is used for the accuracy position deviation signal when the main axis is near the predetermined rotational position). The input signal is an input of the access signal ASV obtained by adding the detection voltages DV ₁ and DV ₃ corresponding to the saturated riggers SRA ₁ and SRA ₂ and the access signal ASV supporting the main axis entering the predetermined position area.

The signal AV indicating the actual speed of the motor 4 is output from the tachometer 5, enters the circuit 11a, and is integrated in the circuit. The cumulative result is subtracted from the initial set voltage ISV described later, and roughly converted into a position deviation signal CPD. The position deviation signal generating circuit 11a generates the constant initial set voltage ISV and the bias signal BIS (Fig. 2 (a)). The value Vi of the voltage ISV is set to be equal to the position deviation voltage corresponding to one rotation (360 °) of the main axis. The position deviation signal generating circuit 11a continuously generates the position command signal ORCN until the time when the main axis reaches the predetermined position at time t ₂ , and generates the initial set voltage ISV when the time t ₁ is reached. Therefore, by the main shaft continues to rotate and the magnet body (10a) (a predetermined portion of the main shaft) reaches the predetermined position of the second rough position error signal CPD the vicinity of the predetermined rotational position (-θ ₁ ~ + θ ₁₎ that is, - It continues to generate until the position indicated by θ ₂ is reached. In addition, a bias signal BIS also occurs until the region is reached.

On the other hand, the accuracy position deviation signal DV ₂ is generated after the magnet body 10a reaches the above-mentioned position vicinity. The result of this operation is the position deviation signal RPD shown in FIG.

The bias signal waveform BIS is deviated from the signal RPD by setting θ ₂ equal to θ ₁ .

Reference is made to FIG. 2 (b) to describe the operation of the control circuit shown in FIG.

The switch 12 during motor rotation is connected to a side in FIG. 1 to form a speed control tupu. In particular, the adder 3a receives the speed command signal CV output from the speed command circuit 1 and the average speed signal AV output from the tachometer 5, and outputs a speed deviation voltage. The voltage-phase converter 3c controls the firing angle of the dilister in the dilister circuit 3d according to the position deviation voltage, and the dilister circuit 3d adjusts the voltage applied to the DC motor 4. . As a result, the actual speed signal AV of the DC motor 4 is adjusted and output to match the command speed signal CV.

Therefore, the speed control loop not only controls the speed of the motor 4 to raise the speed deviation to zero, but also controls to rotate at an approximate command speed during machining.

When the machining operation is completed, a control device such as the numerical control device instructs the exact position command circuit 2 to apply the correct position command signal ORCM to the loop signal switching circuit 11b at time t ₀ .

The speed command signal CV also becomes 0 at this time (figure 2 (b)). As a result, the actual speed signal AV of the motor and the main shaft is reduced to reach zero at time t ₁ . When this operation takes place, a pulse signal VZR indicating zero speed is generated in the positional deviation signal generating circuit 11a, and the loop switching circuit 11b operates the switch 12 to switch to b.

In response to the pulse VZR, the position deviation signal generating circuit 11a first outputs the initial set voltage ISV as the position deviation signal. In response to this signal, the signal AV indicating the actual speed rises to be equal to the value Vi, and the main axis starts to rotate again. When the magnet body 10a on the main shaft continues to rotate to reach the correct position at time t ₂ , the position deviation signal generating circuit 11a outputs a rough position deviation signal CPD as the position deviation signal RPD. When the main shaft continues to rotate and the magnet body 10a reaches the vicinity of the correct position (time t ₃ ), the position deviation signal generating circuit 11a outputs the bias signal BIS as the position deviation signal RPD. Then, when the magnet body reaches the vicinity of the region at the predetermined position (time t ₄ ), the circuit 11a outputs the accuracy position deviation signal DV ₂ .

The main axis position control is completed when the signal DV ₂ drops to zero, that is, when the magnet body 10a is in front of the center of the saturated riacta SAR ₂ .

The structure of the position deviation signal generating circuit 11a is shown in FIG. 5, and the pulse time relationship diagram according to this is in FIG. Parts in FIG. 5 that are similar to those in FIG. 1 are denoted by the same reference numerals and will not be redundantly described again.

In FIG. 5, the circuit 101 is a circuit for generating the initial set voltage ISV and the bias signal BIS, integrating the actual speed voltage signal AV, and subtracting the integration result and the initial set voltage ISV. In particular, the selector switch SW switches to the +15 VOLT side or -15 VOLT side depending on the ejection rotation direction. If the spindle rotates in the forward direction, it is connected to the -15 VOLT side. Assume the changeover switch SW is connected towards -15 VOLT at time t ₁ . The voltage is divided by resistors r ₁ , r ₂ and charges capacitor C past amplifier AMP ₁ and switch S ₀ . The voltage charged in the capacitor becomes the Vi value of the initial set voltage ISV.

When the real speed signal AV is input to the circuit 101 after the switch S ₈ or S ₇ after the switch S ₀ is opened, the capacitor C is discharged to the time constant RC because the voltage value of the real speed signal AV is lower than Vi, and integrated. A coarse position deviation signal CPD obtained as a result of subtraction of the actual speed signal AV and the initial set voltage ISV appears across the output of the amplifier AMP ₂ (integrated circuit consisting of amplifier AMP ₂ , resistor R and capacitance C).

If the switches S ₉ and S ₁₀ are both shorted after the signal CPD reaches the predetermined voltage (time t ₃ ), the circuit 101 operates as an amplifier and a predetermined value of the bias signal BIS appears at the output terminal of the amplifier AMP ₂ .

In other words, the bias signal BIS is output to the initial setting war ISV and roughly the positional deviation signal CPD last depending on the operation and time of the open short circuit operation of the switches S _{7 to} S ₁₀ .

Nos. 102 and 103 denote front end circuits whose switching gains depend on the gear ratio. This circuit operates to increase the gain of the position control loop when the gears in the DC motor 4 and the main shaft 7 are low (large reduction ratio) and to lower the gain when the gear is large (low reduction ratio). That is, the larger the switch S _7, S ₂ ratio short-circuit the switch S _8, S ₃ gotta opening, increase the gain and when the ratio is low the switch S _8, S ₃ is short-circuited, S _7, gotta S ₂ is open Lower the gain This eliminates hunting and overshoot of the spindle when the spindle stops at a predetermined position and allows the spindle stop operation to be completed in a short time regardless of the magnitude of the reduction ratio. Numeral 104 is a known absolute value circuit that makes the absolute value of the output output from circuit 101. The comparator 105 detects whether the coarse position deviation signal CPD has fallen below a predetermined level VO, instructs that a predetermined portion (magnet body 10a) of the main axis is near the correct position, and outputs a signal NRPS.

Signal NRPS shorts switches S ₉ and S ₁₀ . The gain adjusting circuit 106 adjusts the gain in accordance with the gap between the magnet body 10a and the sensor portion 10b and outputs a detection signal DV ₂ (precision position deviation aberration) with a predetermined slope. The slicer circuit 107 splits the approach signal ASV (figure 2 (a)) to a predetermined value, and outputs a signal LS indicating whether the magnet body 10a has reached close to the correct position. Signal LS opens switches S ₅ and S ₆ and shorts S ₄ (time t ₄ ). As a result, the accuracy position deviation signal DV ₂ is output as the position deviation signal RPD.

The forward-reverse switching circuit 108 is controlled when the main shaft rotates in the forward direction to short the switch S ₅ and short the switch S ₆ when rotating in the reverse direction. The " inposition " signal generating circuit 109 including a comparator instructs the accuracy position deviation signal DV ₂ and outputs an imposition signal INPOS when the main axis is near the correct position.

After signal INPOS is generated, it sends the exact position operation completion indication signal to the numerical controller. Comparator 110, 111 indicates an accuracy position deviation signal DV ₂ and detects whether the main axis is approaching the correct position while rotating in the reverse direction (NEG = "1") or in the forward direction (POS = "1"). Output POS.

Switch Ss is shorted in response to signal POS and switch S ₆ is shorted in response to signal NEG. The waveform synthesis circuit 112 outputs an accurate position deviation signal or a rough position deviation signal in accordance with the open short states of the switches S ₄ , S ₅ , and S ₆ .

In summary, when the exact position command signal ORCM becomes logical " 1 _" at time t ₀ , the command speed signal CV drops to zero VOLT, the actual speed is decelerated, and the actual speed signal AV falls to zero VOLT at time t ₁ . At this time, the zero speed signal VZR becomes logical "1", the switch S ₁ is opened, one of S ₂ , S ₃ is shorted according to the high and low setting of the gear, and one of the switches S ₅ , S ₆ is connected to the main shaft rotation. Short circuit depending on forward or reverse application.

This forms a position control loop, and this loop output stage OUT outputs an initial set ISV.

It is important that the switch S ₉ is open S ₇ , S ₈ and S ₁₀ shorted.

With the jeonak ISV response motor is the main axis is rotated to start rotation again so as to reach a predetermined rotation switch to the first position (that is, the signal LS = "1" Information jisyon signal INPOS = "1") then the time t ₂ The switch S ₉ is opened, and one of S ₇ and S ₈ is shorted according to the high and low gear settings.

Therefore, roughly the position deviation signal CPD is output from the output terminal OUT. Then, the actual speed signal AV and the position deviation signal are reduced, and when the main axis reaches the exact position near the second time t ₃ , the comparator 105 outputs a signal NRPS (logical "1") to short the switches S ₉ and S ₁₀ . Let's do it. As a result, the bias signal BIS of a predetermined level is output from the output terminal OUT. When the main axis rotates slowly and reaches the correct position (time t ₄ ), the signal LS becomes "1", the switches S ₅ and S ₆ are open and S ₄ is shorted. Accuracy The position deviation signal DV ₂ is output from the output terminal OUT.

According to the present invention, the main shaft can be stopped at a predetermined rotational position accurately without contacting such as mechanical braking. A highly accurate proximity switch is constructed, and when the specific position on the main axis reaches the predetermined rotational position, the accuracy position deviation is output and extremely high accuracy of ± 0.03 ° to ± 0.05 ° is obtained.

By integrating the output warp output from the tachometer to output the rough position deviation signal, it is possible to lower the price when the position control loop is configured without using a position sensor other than the proximity switch. Since the gain of the position control system is a mechanism that can be switched according to the gear deceleration rate, the gain can be prevented from hunting and overshoot, and can be set appropriately to shorten the time required for the position.

Although the present invention has been set in the specific aspect as described above, it is obvious that various modifications, modifications and variations are possible. Therefore, the foregoing and modifications will be made in the following claims.

Claims (1)

When the current position of the predetermined part of the main axis and the predetermined part of the main axis are stopped, the positional deviation between the exact position becomes zero, and the predetermined control part of the main axis reaches the correct position. A sensor for generating a predetermined voltage signal and generating a positive or negative voltage signal with respect to the predetermined pulse when the predetermined portion of the main axis is at the opposite end of the correct position and generating an accurate position deviation voltage that crosses the pulse; Means for outputting roughly the positional deviation voltage according to the positional deviation between the specific position and the correct position, and outputs the roughly positional deviation voltage as the positional deviation signal until a predetermined portion of the main axis reaches the exact position, Position deviation signal generating means and main axis on outputting accuracy position deviation whole signal as position deviation signal after reaching near exact position Position control is performed based on the approximate position deviation voltage until the predetermined part reaches the near position.After the predetermined part on the main axis reaches the near position, the accuracy position deviation voltage drops to zero, and the predetermined part is returned to the correct position. Spindle stop control device, characterized in that composed of means for stopping.

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