JPH05192849A - Device for detecting stopping of rotation of rotary machine - Google Patents

Abstract

PURPOSE:To provide a device for detecting stopping of rotation of a rotary machine, capable of outputting the point of time of finish of machining as reliable information after the rotary machine has machined material. CONSTITUTION:The rotary motion of a rotary machine 1 is transmitted by an air pintle 2. A pulse of a frequency corresponding to the number of rotation is obtained from an encoder 3 mounted to the air pintle 2 and is converted into voltage by an F/V convertor 5. This output is compared with a reference voltage 6 corresponding to a first predetermined number of rotation by a comparator 7. The output is also compared with a reference voltage 9 corresponding to a second predetermined number of rotation by a comparator 10. As the number of rotations is decreased and the comparator 7 is inversed, a retriggerable on-shot mutlivibrator 8 operates and outputs a pulse (C) of a fixed width of time. As the number of rotations is further decreased, the comparator 10 is inversed and outputs a pulse (D). The logical product of the pulses (C) and (D) is obtained to provide an output (E).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a rotary processing machine, and more particularly to a rotation stop detecting device for a rotary processing machine using an air spindle.

[0002]

2. Description of the Related Art A rotary machining machine such as a milling machine or a machining center, especially a machining machine equipped with an air spindle whose spindle is supported by an air bearing, has a very quiet rotation sound, which causes an error in operator judgment. Since it is dangerous in terms of work such as inducing it, it is necessary to detect whether or not the rotary processing machine is rotating and provide a fail-safe function.

Therefore, conventionally, whether or not the rotary processing machine is rotating is detected based on a command signal for driving the control motor or a feedback signal indicating that the rotary processing machine is rotating. Was detected by. In addition, some rotary processing machines do not have the above display function at all.

[0004]

However, in the above-described conventional rotation detection method for the rotary processing machine, since it is merely a judgment as to whether or not it is rotating, when the stop state is detected, the stop state indicates the material. It is not possible to determine whether the machine is in a stopped state before processing or after processing, and it is not necessary to simply use it as a confirmation of the operator's stop.
For example, there is an unsolved problem that the information content is insufficient for the controller to handle it as operation status information for automation.

Therefore, the present invention has been made by paying attention to the above-mentioned unsolved problems of the prior art, and is capable of reliably recognizing that the material processing has been completed and the machine is in a stopped state. It is an object of the present invention to provide a rotation stop detection device for the above.

[0006]

In order to achieve the above object, a rotation stop detecting device for a rotary processing machine according to a first aspect of the present invention comprises:
In a rotary processing machine using a spindle, a rotation speed reduction detecting means for detecting that the spindle rotation speed at the end of processing has become below a predetermined rotation speed, and a decrease in the spindle rotation speed is detected by the rotation speed reduction detecting means. And a machining end signal generating means for generating a pulse for a certain period of time after the rotation is stopped.

Further, a rotation stop detecting device for a rotary processing machine according to a second aspect of the present invention detects, in a rotary processing machine using a spindle, that the spindle rotational speed at the end of processing is equal to or lower than a first predetermined rotational speed. A first rotation speed decrease detecting means, a second rotation speed decrease detecting means for detecting that the spindle rotation speed is equal to or lower than a second predetermined rotation speed lower than a rotation speed of a first predetermined rotation speed, and A pulse generating means for generating a pulse for a certain period of time after the rotation is stopped by the one rotation speed decrease detecting means after the rotation speed is detected, an output of the pulse generating means, and an output of the second rotation speed decrease detecting means. And a processing end signal generating means by a logical product of.

[0008]

In the rotation stop detecting device for the rotary processing machine according to the first aspect, a pulse is used as a processing end signal for a certain period from when the spindle rotation speed at the end of processing becomes equal to or less than a predetermined rotation speed and after the rotation is stopped. Since it is output, it can be reliably used as a machining end signal for rotary machining.

In the rotation stop detection device for a rotary processing machine according to a second aspect of the present invention, a pulse is generated for a certain period from the time when the spindle rotation speed at the end of processing falls below the first predetermined rotation speed until the rotation is stopped. However, since the signal output by the logical product of the pulse and the second predetermined rotation speed decrease detection signal after the spindle rotation speed becomes equal to or less than the second predetermined rotation speed is output as the processing end signal, noise is generated. It can be used as a machining end signal for reliable rotation machining without malfunction.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention. In FIG. 1, reference numeral 21 denotes a rotary processing machine such as a milling machine or a machining center, which has an air spindle 22 for mounting and holding a cutting tool at its tip and being rotationally driven by a rotary drive source such as an electric motor. An encoder 23 is attached to the encoder 23, and the encoder 23 outputs a pulse signal corresponding to the rotation frequency proportional to the rotation speed. The pulse signal output from the encoder 23 is received by the buffer circuit 24, and F /
It is input to the V converter 25. The F / V converter 25 converts the pulse signal into a voltage level according to its frequency.
Then, the converted voltage level is output to the comparator 27.
Entered in.

Non-inverting input side (+ side) of comparator 27
The reference voltage v, which is the output of the reference voltage generator 26 that generates the reference voltage corresponding to the predetermined rotation speed f ₁ , is input to
Further, the output voltage level of the F / V converter 25 is input to the inverting input side (-side). Then, the comparator 27
Output is a low-pass filter (hereinafter referred to as LPF)
One shot multivibrator (hereinafter referred to as MM) 2 after being input to 28 to remove noise components.
9, the MM 29 outputs a pulse having a constant time width as a processing end signal from the time when the output signal of the comparator 27 rises. Further, a power-on reset signal is input to the MM 29 to prevent a malfunction when the power is turned on. Then, the processing end signal output from the MM 29 is supplied to the outside and used for processing end notification and automation by the controller.

Here, the F / V converter 25, the reference voltage generator 26 and the comparator 27 correspond to the rotation speed decrease detecting means, and the LPF 28 and the MM 29 correspond to the machining end signal generating means. Next, the operation of the first embodiment will be described with reference to the time chart of FIG. Rotary processing machine 21
When the start of the rotation operation at time T ₀ , the F / V converter 25 obtains a voltage output corresponding to the spindle speed as shown in FIG. 2 (a). That is, when the rotary processing machine 21 starts to rotate at the time T ₀ , the voltage gradually starts to increase from the time T ₀ and maintains a high voltage equal to or higher than the reference voltage v at the processing stage. The voltage starts decreasing and becomes lower than the reference voltage at the time point T ₂ , and at the time point T ₃ , F /
The output voltage of the V converter 25 becomes zero. Therefore, time T
_When the voltage output after ₁ reaches the reference frequency f ₁ which is still close to 0, the comparator 27 causes the (b) signal shown in FIG. 2 to fall.

Then, the rotary processing machine 21 finishes the processing work.
Then, the rotation speed begins to decrease and ₂And the reference frequency f₁
When it becomes lower, the comparator 27 raises the (b) signal.
Get out. This (b) signal is, for example, an emergency stop on another line.
To remove noise components that may be generated by
Is input to the LPF 28. This (b) signal rises
Time T₂Then the MM29 starts its operation and T₂Rotation from
Time point T at which it completely stops₃Later time T_FourUntil fixed time
Generates the machining end signal (c). This processing end signal (c)
Ensures that the machine is in a stopped state after processing.
It is possible to distinguish it from the stopped state before processing. That
Then, using this processing end signal (c), the external controller
To notify the end of work or suppress the restart,
It is possible to have a function to prevent accidental transfer to the process
It

Next, a second embodiment of the present invention will be described with reference to the schematic block diagram shown in FIG. In FIG. 3, reference numeral 1 is a rotary processing machine such as a milling machine or a machining center, which has an air spindle 2 for mounting and holding a cutting tool at its tip and being rotationally driven by a rotary drive source such as an electric motor,
An encoder 3 is attached to the air spindle 2, and the encoder 3 outputs a pulse signal corresponding to a rotation frequency proportional to the rotation speed. The pulse signal output from the encoder 3 is received by the buffer circuit 4, and the F / V
It is input to the converter 5. The F / V converter 5 converts the rotation frequency into a voltage level according to the frequency. The converted voltage level is then compared to the comparators 7 and 1
Input to 0.

The reference voltage v ₂ which is the output of the reference voltage generator 6 for generating the reference voltage corresponding to the first predetermined rotation speed f ₂ is input to the inverting input side (-side) of the comparator 7, and An F / V converter 5 is provided on the non-inverting input side (+ side).
The output voltage level of is input. Then, the output of the comparator 7 is input to a retriggerable one-shot multivibrator (hereinafter, referred to as RMM) 8, and the RMM 8 outputs a pulse having a constant time width from the time when the output signal of the comparator 7 falls.

[0016] On the other hand, to the non-inverting input of comparator 10 (+ side), the reference voltage v ₁ which is the output of the reference voltage generator 9 for generating a reference voltage corresponding to the second predetermined rotational speed f ₁
Is input, and the output voltage level of the F / V converter 5 is input to the inverting input side (-side). Then RMM
The pulse of a constant time width, which is the output of 8, is the AND circuit 11 whose input is the output signal of the comparator 10 at the other input.
Connected to one input. The output of the AND circuit 11 is supplied to the outside as a processing end signal and can be used for work end notification and automation by the controller.

FIG. 4 is a concrete circuit diagram for realizing the second embodiment. Detailed constants of each part are omitted because they can vary depending on the system. Here, the F / V converter 5, the reference voltage generator 6 and the comparator 7 correspond to the first rotation speed reduction detecting means, and the F / V converter 5, the reference voltage generator 9 and the comparator 10 are the second. The RMM 8 corresponds to the pulse generation means, which corresponds to the rotational speed decrease detection means, and the comparator 10 and the logical product circuit 11
Corresponds to the processing end signal generating means.

Next, the operation of the above embodiment will be described with reference to the time chart of FIG. When the rotary processing machine 1 starts to rotate at the time point t ₀ , the F / V converter 5 obtains a voltage output corresponding to the spindle speed as shown in FIG. That is, when the rotary processing machine 1 starts to rotate at the time t ₀ , the voltage gradually starts to increase from the time t ₀ and exceeds the reference voltage v ₁ at the time t ₁ and further increases to the time t at the processing stage. maintaining the reference voltage v ₂ higher than the voltage at _2, the time when to end the machining voltage gradually begins to decrease t ₃
In reference voltage v is ₂ or less, when more voltage drops t
It becomes the reference voltage v ₁ or less at ₄ and F / V at time t ₅ .
The output voltage of the converter 5 becomes zero. Therefore, when the rotary processing machine 1 starts to rotate at the time point t ₀ , the comparator 10 is shown in FIG. 5 when the voltage output after the time point t ₁ reaches the reference frequency f ₁ which is still close to zero. D) Turn off the signal.

Next, at time t ₂ , the reference frequency f ₂
7 is reached, the comparator 7 is shown in FIG.
(B) Raise the signal. Next, when the rotary processing machine 1 finishes the processing work and the rotation speed starts to decrease and becomes lower than the reference frequency f ₂ at time t ₃ , the output of the comparator 7 is inverted and falls. At this falling timing, the RMM 8 starts its operation and outputs the (C) signal shown in FIG. This (C)
The pulse width of the signal is T = K, as shown in FIG.
-Has a fixed time width represented by C _X · R _X. This fixed time width is set to continue until t ₆ after the complete stop.

Next, when the rotation of the rotary processing machine 1 further decreases and becomes lower than the reference frequency f ₁ at time t ₄ , the output (D) signal of the comparator 10 is inverted and rises as shown in FIG. The rising edge of this (D) signal confirms that the rotation has stopped. The (C) signal which is the output of the RMM 8 and the output of the comparator 10
(D) If the logical product with the signal is taken by the logical product circuit 11, the time t
₄ between ~t ₆ is output as an output (E) signal of the AND circuit 11, the (E) signal is the processing end signal.

The processing end signal (E) makes it possible to surely recognize that the machine is in a stopped state after the processing is completed, and to distinguish it from the stopped state before the processing. Then, by using the processing end signal (E), it is possible to give a function of notifying the external controller of the end of the work or suppressing the restart, thereby preventing the careless transfer to the next process. Where by any chance,
(B) Even if the comparator 7 causes chattering at the rising edge of the signal, the RMM 8 operates due to the chattering at the rising edge of the signal (B) to generate an erroneous pulse with a constant time width T. Since the (D) signal has already fallen, the (E) signal is not output and it can be said that the circuit operation is stable. Further, for example, even if a noise component is superposed due to an emergency stop of another line, the logical product circuit 11 takes a logical product, so that it is not affected by noise and it can be said that the circuit operation is stable in this respect as well.

Although the retriggerable one-shot multivibrator 8 is used in the second embodiment,
The present invention is not limited to this, and for example, a combination of an integrating circuit and a Schmitt trigger circuit or a comparator may be used. Further, in the second embodiment described above, F
Although the / V converter 5 is used, the present invention is not limited to this, and an integrating circuit having a constant time constant may be used. In this case, when the retriggerable one-shot multivibrator is used for the output of the comparator 10, a clear waveform (E) in FIG. 5 is obtained without being affected by the chattering of the comparator due to the use of the integrating circuit.

[0023]

As described above, according to the rotation stop detecting device for a rotary processing machine according to the first aspect of the present invention, the rotation speed of the spindle is decreased from the time when the decrease in the rotation speed of the spindle due to the end of the processing is below the predetermined rotation speed. Since the signal is output only during the period after the stop, it can be surely recognized as the processing end signal of the rotary processing, so the system can be automated and the effect that the operator can safely move to the next process is expected. it can.

Further, according to the rotation stop detection device for a rotary processing machine according to the second aspect, the rotation is stopped from the time when the decrease in the rotation speed of the spindle at the end of the processing becomes the first predetermined rotation speed or less. A machining end signal is generated by generating a pulse for a certain period of time, and outputting a signal obtained by a logical product of the pulse and the second predetermined rotation speed decrease detection signal after the rotation speed of the spindle becomes equal to or lower than the second predetermined rotation speed. As a result, in addition to the effect of claim 1, the effect that a stable circuit that is not easily affected by disturbance or noise can be configured can be expected.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment.

FIG. 2 is a time chart of the first embodiment.

FIG. 3 is a schematic configuration diagram of a second embodiment.

FIG. 4 is a specific circuit diagram of the second embodiment.

FIG. 5 is a time chart of the second embodiment.

[Explanation of symbols]

 1, 21 Rotation processing machine 2, 22 Air spindle 3, 23 Encoder 4, 24 Buffer circuit 5, 25 F / V converter 6, 9, 26 Reference voltage 7, 10, 27 Comparator 8 Retriggerable one-shot multivibrator 11 Logic Product circuit 28 Low-pass filter 29 One-shot multivibrator

Claims (2)

[Claims] 1. In a rotary processing machine using a spindle, a rotation speed reduction detecting means for detecting that the spindle rotation speed at the end of processing has become a predetermined rotation speed or less, and a spindle rotation speed by the rotation speed reduction detection means. Stop detection device for a rotary processing machine, comprising: a machining end signal generating means for generating a pulse for a certain period of time after the rotation is stopped after the decrease of the 2. In a rotary processing machine using a spindle, a first rotation speed decrease detecting means for detecting that the spindle rotation speed at the end of processing is equal to or lower than a first predetermined rotation speed, and the spindle rotation speed is A second rotation speed decrease detecting means for detecting that the rotation speed is lower than a second predetermined rotation speed lower than the rotation speed of the first predetermined rotation speed, and a time point when the decrease in the rotation speed is detected by the first rotation speed decrease detecting means. From a pulse generation means for generating a pulse for a certain period after the rotation is stopped, and a machining end signal generation means by a logical product of the output of the pulse generation means and the output of the second rotation speed decrease detection means. A device for detecting the rotation stop of a rotating machine.