JPH05333034A - Detecting apparatus of rotation speed - Google Patents

Abstract

PURPOSE:To obtain a rotation speed detecting apparatus which surely detects the rotation speed of a rotary body even when the rotary body rotates at low speeds. CONSTITUTION:Rotary pulse signals of a frequency corresponding to the rotating speed are input from a rotary encoder 3 mounted on a rotary body, and pulse signals generated with a constant predetermined cycle are input from an unstable multivibrator 6, to the apparatus. The rotary pulse signals from the rotary encoder 3 are counted every interval of the constant cycle pulse signals from the unstable multivibrator 6, so that the number of input pulses per constant time is obtained. When the number of pulses is processed through analog conversion and integration, the output voltage of the level corresponding to the rotating frequency of the rotary body is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation speed detecting device for detecting the rotation speed of a rotating body.

[0002]

2. Description of the Related Art A rotary processing machine such as a milling machine or a machining center, especially a processing machine equipped with an air spindle whose spindle is supported by an air bearing, has a very quiet rotation sound, and therefore the rotation processing machine rotates. It is necessary to detect whether the rotary processing machine is rotating or not to provide a fail-safe function because it involves a risk of work such as inducing an operator's judgment error when determining whether or not it is rotating. It was

Therefore, to detect whether or not the rotary processing machine is rotating, for example, a pulse signal corresponding to a rotation frequency proportional to a rotation speed output from an encoder mounted on the air spindle is taken out and F / The V converter converts the pulse signal into a voltage level corresponding to the frequency, thereby detecting the rotation speed of the rotary processing machine and stopping when the rotation speed becomes zero.

[0004]

However, in the conventional method for detecting the number of revolutions, the number of revolutions is detected by using the F / V converter, and the F / V converter utilizes charge / discharge of the capacitor. Since the frequency is converted to a voltage level according to the frequency, it is difficult to detect the rotation speed with high accuracy when the rotation speed of the rotary processing machine is low. When applied to a rotation stop detection device,
Even if the rotary processing machine is rotating at low speed, F /
Since the V converter cannot detect the number of rotations, the rotary processing machine determines that it is in a stopped state, which poses an unsolved problem that poses a danger to the operator during work.

Therefore, the present invention has been made by paying attention to the above-mentioned unsolved problems of the prior art, and the number of revolutions can be surely detected even when the rotary processing machine is rotating at a low speed. An object is to provide a detection device.

[0006]

In order to achieve the above object, a rotation speed detecting device according to the present invention is a rotation speed detecting device for detecting the rotation speed of a rotating body, wherein a pulse signal is generated in accordance with the rotation of the rotating body. First pulse generating means for generating, second pulse generating means for generating a pulse signal of a predetermined cycle,
And pulse counting means for counting the output pulses of the first pulse generating means by the intervals between the output pulses of the second pulse generating means.

[0007]

In the present invention, the pulse signal from the first pulse generating means for generating a pulse signal in accordance with the rotating operation of the rotating body and the pulse signal from the second pulse generating means for generating a pulse signal of a predetermined cycle. By inputting and, the output pulse of the first pulse generating means is counted by the interval between the output pulses of the second pulse generating means to obtain the pulse number of the rotating body at every constant time, and the pulse number is converted into an analog value By converting, the voltage level according to the rotation speed of the rotating body is detected.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram in which the rotation speed detection device according to the present invention is applied to a rotation stop detection device of a rotary processing machine. In FIG. 1, reference numeral 1 denotes 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. A rotary encoder 3 as a first pulse generating means is attached to the rotary encoder 3, and a rotary pulse signal A having a frequency proportional to the rotation speed is output from the rotary encoder 3.

The pulse signal A output from the rotary encoder 3 is input to a counter 5 as pulse counting means via a buffer amplifier 4. Counter 5
A fixed-cycle pulse signal B from an astable multivibrator 6 as a second pulse generating means for generating a pulse signal of a predetermined cycle, and an air spindle 2 from a buffer amplifier 4.
When the rotation pulse signal A corresponding to the rotation speed of is input and the fixed period pulse signal B is input, the count value C at that time is latched by the internal latch circuit, and then the count value is reset to Start counting signal A.

Here, the period and pulse width of the fixed-cycle pulse signal B from the multivibrator 6 are set by the braking characteristics of the rotary processing machine, and hunting occurs while ensuring the detection accuracy of the rotational speed. A value that does not exist (for example, if the signal A is about several kHz, the cycle is 10 to 1).
00 msec). The count value C latched by the latch circuit of the counter 5 is input to the D / A converter 7, converted into an analog value, and then converted into a low-pass filter (hereinafter, LPF).
8). The LPF 8 integrates the input analog signal D and outputs the output voltage level E corresponding to the rotation speed of the air spindle 2 to the comparators 10 and 11.
Output to.

Here, the rotary encoder 3, the buffer amplifier 4, the counter 5, the astable multivibrator 6,
The D / A converter 7 and the LPF 8 constitute a rotation speed detection device 20. Inverting input side (-side) of comparator 10
Is supplied with a reference voltage V1 which is an output of a reference voltage generator 9 for generating a reference voltage corresponding to the first predetermined rotation speed f1, and the non-inverting input side (+ side) has a rotation speed detection device. The output voltage level E of 20 is input. Then, the output F of the comparator 10 is input to a retriggerable one-shot multivibrator (hereinafter referred to as RMM) 13, and the RMM 13 outputs a pulse G having a constant time width from the time when the output signal of the comparator 10 falls. To do.

On the other hand, on the non-inverting input side (+ side) of the comparator 11, the reference voltage V which is the output of the reference voltage generator 12 which generates the reference voltage corresponding to the second predetermined rotation speed f2.
2 is input, and the output voltage level E of the rotation speed detection device 20 is input to the inverting input side (− side). Next, the pulse G having a constant time width, which is the output of the RMM 13,
The other input is connected to one of the AND circuits 14 having the output H of the comparator 11 as an input. Then, the output of the AND circuit 14 is supplied to the outside as the processing end signal I.

Next, the operation of the above embodiment will be described with reference to a time chart showing the operation of the rotation stop detecting device of the rotary processing machine, and the time chart showing the operation of the rotation speed detecting device at the start of rotation and at the stop of rotation. It will be described with reference to FIG. Figure 2
In FIG. 3A, when the rotary processing machine 1 starts the rotation operation at time T0, the rotary encoder 3 outputs a rotation pulse signal A having a cycle and a pulse width corresponding to the rotation speed of the air spindle as shown in FIG. 3A. Is output. As the rotation speed increases, the pulse width of the rotation pulse signal A gradually becomes shorter and the pulse interval also becomes shorter. In the counter 5, the constant period pulse signal B (FIG. 3B) is input from the astable multivibrator 6 at a constant time interval Q, and when input, the count value C at that time is latched by the internal latch circuit. After that, by resetting the count value C, the number of pulses of the rotation pulse signal A per constant time is counted. In this case, as shown in FIGS. 3 (a) and 3 (c),
The count value C becomes "1" at the time points P1 and P2 at which the constant-cycle pulse signal B is input, "2" at the time point P3, and "4" at the time point P4, and the count value C increases as the rotation speed of the rotary processing machine 1 increases. To increase. This count value C is D / A
It is converted into an analog value D by the converter 7 (FIG. 3 (d)), and L
As the voltage level E corresponding to the rotation frequency of the rotary processing machine 1 after being integrated by the PF 8, a waveform that gradually increases is output as shown in FIG.

Thus, by counting the rotation pulse signal A at the very low speed rotation at the start of rotation, the voltage level E corresponding to the rotation frequency can be output, and the rotation speed can be reliably detected. .. At this time,
In FIG. 2A, when the rotation speed of the rotary processing machine 1 increases and the voltage level E reaches the reference voltage V1 corresponding to the reference frequency f1 which is still close to 0 at time T1, the comparator 11 operates as shown in FIG. As shown in (d), the rotation stop detection signal H falls. Next, when the voltage level E reaches the reference voltage V2 corresponding to the reference frequency f2 at the time point T2, the comparator 10 sets the F level as shown in FIG.
Raise the signal.

The voltage level E becomes higher than the reference voltage V2,
At the processing stage, the pulse width and pulse interval of the rotation pulse signal A become shorter and the count value C becomes larger. On the other hand, when processing is completed, the rotation speed gradually decreases,
Along with this, the pulse width and the pulse interval of the rotation pulse signal A gradually increase, and the output signal F of the comparator 10 inverts and falls at the time T3 when the voltage level E becomes equal to or lower than the reference voltage V2. RMM13 at this falling timing
Starts its operation and outputs the signal G shown in FIG. The pulse width L of the G signal is a constant time width set to continue until T6 after the complete stop.

Next, when the rotation of the rotary processing machine 1 is further decelerated and the voltage level E falls below the reference voltage V1 corresponding to the reference frequency f1 at time T4, the output signal H of the comparator 11 is shown in FIG. 2 (d). It flips and stands up.
The rising of the output signal H of the comparator 11 confirms that the rotation has stopped. And RM
Output signal G of M13 and output signal H of comparator 11
If the logical product with is obtained by the logical product circuit 14, the time T4 to T6
Is output as the output signal I of the AND circuit 14, and this I signal becomes the processing end signal (FIG. 2 (e)).

A time chart of the rotation speed detecting device 20 when the rotary processing machine is stopped is as shown in FIG.
In FIG. 4, the number of pulses of the rotation pulse signal A decreases as the rotation processing machine 1 approaches the stop, and the count value C at the time point P11 when the constant period pulse signal B is input.
(FIG. 4C) is "4", the time value P12 is "2", the time point P13 is "1", the time point P14 is "1", and the count value C is gradually decreased, and the time point P15 is "0". Becomes Therefore, the voltage level E obtained by analog-converting the count value C by the D / A converter (FIG. 4 (d)) and integrating by the LPF 8 has a waveform that gradually decreases as shown in FIG. 4 (e). Then, when the count value C becomes "0" at the time point P15, the rotation of the air spindle 2 is stopped, and the counter output is "0", so the voltage level E becomes "0" and the rotation speed. "0" is detected.

Therefore, according to the above embodiment, the rotary encoder 3 is attached to the air spindle 2, a pulse signal is generated in accordance with the rotation of the air spindle 2, the pulse signal is counted at regular time intervals, and the count number is analogized. Since the number of revolutions of the air spindle 2 is detected by the conversion, the number of revolutions can be surely detected even at the time of low speed rotation at the time of starting rotation or stopping the rotation.

Further, when the present invention is applied to the rotation detecting device of the rotary processing machine, the number of rotations of the rotary processing machine can be surely detected even at the low speed rotation immediately before the rotation is stopped.
The rotation stop of the rotary processing machine can be reliably detected, and the effect of ensuring the safety of the operator can be obtained. In addition, although the case where the astable multivibrator 6 is applied as the second pulse generating means has been described in the above embodiment, the present invention is not limited to this, and other pulse generating means such as a blocking oscillation circuit is applied. Of course, it is possible.

Further, in the above embodiment, the case where the counter 5 is applied as the counter means has been described. However, the present invention is not limited to this, and arithmetic means such as a microcomputer may be applied to perform digital arithmetic.

[0021]

As described above, according to the rotation speed detecting device of the present invention, the pulse signal generated by the rotation of the air spindle is counted at every constant time, and the count value per constant time is analogized. Since the rotation number of the air spindle is detected by converting the value into a value and performing the integration process, the rotation number can be reliably detected regardless of the rotation speed of the air spindle.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a rotation speed detection device according to the present invention.

FIG. 2 is a time chart of a rotation stop detection device for a rotary processing machine to which the present invention is applied.

FIG. 3 is a time chart of the present invention.

FIG. 4 is a time chart of the present invention.

[Explanation of symbols]

 1 rotary processing machine 2 air spindle 3 rotary encoder 4 buffer amplifier 5 counter 6 astable multivibrator 7 D / A converter 8 low pass filter (LPF) 9, 12 reference voltage 10, 11 comparator 13 retriggerable one-shot multivibrator 14 AND circuit

Claims (1)

[Claims] 1. A rotation speed detection device for detecting the rotation speed of a rotating body, wherein the first pulse generating means generates a pulse signal in accordance with the rotation of the rotating body, and the second pulse generating a pulse signal of a predetermined cycle. A rotation speed detecting device comprising: a generating means; and a pulse counting means for counting the output pulse of the first pulse generating means by an interval between output pulses of the second pulse generating means.