JPH0692040B2 - Motion monitoring device for press machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a motion monitor device for a press machine.

[Prior Art] In a press machine, a crankshaft angle is detected by an absolute encoder, and a slide is stopped at a top dead center by a timing signal (press stop signal) output at the set crankshaft angle. In this case, the timing signal for activating the clutch brake is output at the crankshaft angle determined in consideration of the coasting distance.

Here, the absolute encoder has a configuration in which a large number of tandemly arranged disk cams that can be rotated synchronously via a crankshaft, a gear mechanism, a coupling mechanism, and the like, and limit switches that are arranged corresponding thereto. It is common to have

Therefore, the gear mechanism, the drive shaft, etc. may be damaged, and the disc cam may become loose or come off. If left unattended, there is a strong possibility that it will fall twice and cause a serious accident.

For this reason, conventionally, a top dead center proximity switch that detects top dead center by engaging with a main gear, a cam, etc. is provided, and when this top dead center proximity switch is activated, it is determined that the absolute encoder is abnormal. It was configured to stop the press with a top dead center proximity switch.

[Problems to be Solved by the Invention] By the way, the top dead center proximity switch is set to a position beyond the top dead center because it determines whether or not the slide has stopped at the top dead center. Generally, it is set at +7.5 degrees from top dead center.

Therefore, as shown in FIG. 3 (A), for example, the press stop signal from the absolute type encoder is changed to the angle θ3.
In the case of a press machine that stops the press at the top dead center (0 degree) to +7.5 degrees by outputting at, the output signal from the top dead center proximity switch can be used to make an emergency stop, as shown by the dotted line. It is safe because it can be stopped reliably without reaching the dangerous area near the dead point.

However, 400 to 1,0 was created based on the demand for higher speed.
In a high-speed, ultra-high-speed type press machine such as 00Spm, as shown in Fig. 3 (B), the press stop signal should be originally issued at an angle θ2 close to the bottom dead center. Even if a stop signal is output by the top dead center proximity switch at 5 degrees, the coasting distance is so large that the slide may reach the critical area such as passing through bottom dead center as shown by the dotted line. Very dangerous.

Thus, there is a strong demand for development of a highly practical device capable of reliably and promptly monitoring the presence or absence of an abnormality in addition to improving the reliability of the absolute encoder.

Further, if it is possible to monitor in advance that the brake operation that can surely stop the slide at the top dead center can be monitored, it is convenient to handle, and it is required to develop a device also having such a brake monitor function.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a low-cost and convenient motion monitor device for a press machine, which is capable of promptly and reliably monitoring the abnormality of an absolute encoder and has a brake monitor function.

[Means for Solving the Problems] According to the present invention, reliability cannot be improved unless it is separated from the absolute type encoder and its drive system, and in a press machine, the main gear is mechanically highly reliable and considerably many. The number of teeth of the main gear is counted and the angle of the crankshaft is calculated by focusing on the unique configuration of the press machine, such as the fact that the encoder has a large number of teeth and the incremental encoder is extremely inexpensive compared to the absolute encoder. An incremental encoder for detection is provided and the output signal of this encoder is compared with that of an absolute encoder to enable quick and reliable monitoring.

That is, in a press machine that has an absolute encoder that detects the absolute angle of the crankshaft angle and outputs a press stop signal at the set crankshaft angle, a top dead center detection that detects the top dead center of the slide by engaging with the cam mechanism. And an incremental encoder formed to count the number of teeth of the main gear to detect the crankshaft angle and to be zero-cleared by the output signal of the top dead center detector, and detected by the absolute encoder. After comparing the crankshaft angle and the crankshaft angle detected by the incremental encoder and outputting an abnormal signal when there is a difference between the two, after the press stop signal or the abnormal signal is output. , The rate of change of the crankshaft angle detected by at least one of the two encoders is In the case of determining that the brake operation normally constant is configured with a braking operation confirmation means for determining the brake operation error in the case of decreasing at a constant rate.

[Operation] In the present invention having the above-described configuration, the absolute encoder always detects the absolute value of the crankshaft angle during the press operation, and outputs the press stop signal when the detected crankshaft angle becomes equal to the set crankshaft angle. . Therefore, the slide coasts and then stops at top dead center.

The incremental encoder detects the crankshaft angle while being cleared to zero by the top dead center detector at the top dead center. The comparison means compares the output signals of both encoders moment by moment.

Here, when the absolute encoder fails, if one or more teeth of the main gear moves when the set crankshaft angle is exceeded, the comparison means detects the difference and issues an abnormal signal.

Therefore, if this abnormal signal is used as an emergency press stop signal, it is possible to perform an appropriate motion monitor that can be used to stop the slide just beyond the top dead center.

In addition, the brake operation confirmation means confirms in advance whether the brake operation that can reliably stop the slide at the top dead center has been performed based on the change rate of the crankshaft angle detected by the absolute encoder or the incremental encoder. You can know

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the motion monitor apparatus of this embodiment includes a top dead center detector 10 and an incremental encoder.
20, an absolute encoder 30, a comparison means 40, and a brake operation confirmation means 50.

In the figure, 1 is a main gear with 80 teeth (pitch 4.5 degrees)
Have. Further, 9 is a cam mechanism which rotates in synchronization with the main gear. 2 is a clutch brake, and 7 is a switching circuit.

First, the absolute encoder 30 has the gear mechanism 4,
It is synchronously driven by the main gear 1 via the connecting mechanism 5,
An angle detection signal having a resolution of 4.5 degrees or less can be output to the comparison means 40 and the brake operation confirmation means 50. Further, it has a function of operating the clutch brake 2 when the set crankshaft angle (for example, 210 degrees) is reached, releasing the clutch and operating the brake to output a press stop signal.

On the other hand, the incremental encoder 20 has a detector 21
And a detection circuit 22. The detection unit 21 emits a pulse signal each time it detects a tooth of the main gear 1 that rotates, and the detection circuit 22 is formed of a counter that counts the pulse signal. The count value is zero-cleared by the output signal of the top dead center detector 10 set at the position corresponding to the top dead center.

Further, the detection circuit 22 can output the crankshaft angle which is cleared to zero at each top dead center and is synchronized with the rotation of the main gear 1 to the comparison means 40 and the brake operation confirmation means 50. This resolution is equal to a tooth pitch of 4.5 degrees.

Next, the comparison means 40 is composed of a comparator that compares the crankshaft angle signal detected by the encoder 30 with the crankshaft angle signal detected by the encoder 20 (detection circuit 22). The configuration is such that an abnormal signal ε is output when a difference of 4.5 degrees or more occurs.

Although the abnormal signal ε can be used for an alarm or the like,
In this embodiment, the clutch brake 2 is operated so as to operate the switching circuit 7 and stop the press emergency.

That is, the comparison means 40 has a pitch 4.
It is formed so that the presence or absence of an abnormality in the absolute encoder 30 and the press motion can be monitored at 5 degrees.

The brake operation confirming means 50 is means for confirming both the brake operation of the absolute encoder 30 in a normal state and the brake operation based on the abnormal signal ε from the comparing means 40. That is, regardless of whether the absolute type encoder is normal or abnormal, it is possible to monitor in advance that an operation that can reliably stop the slide at the top dead center has been performed.

Specifically, the speed change rate of the output signal from the absolute encoder 30 or the output signal of the incremental encoder 20 (detection circuit 22) after the set crankshaft angle equivalent signal or the abnormal signal ε is output. Is formed so that it can be detected and detected.

Next, the operation will be described.

First, the set crankshaft angle of the absolute encoder 30 is set in correspondence with the coasting distance based on Spm of the press machine.

That is, as shown in FIG. 2, it is assumed that the set crankshaft angle is set to θ1 in order to stop the sliding within 0 to α degrees around the clockwise direction from the top dead center.

Here, when the press operation is started, the absolute encoder 30 and the incremental encoder 20 both operate in accordance with the rotation of the main gear 1.

The absolute encoder 30 always detects the absolute angle of the crankshaft angle with the top dead center as the reference angle (0 degree). Then, when the detected crankshaft angle becomes equal to the set crankshaft angle θ1, the clutch brake 2 is operated.
As a result, the slide is stopped within α degrees from top dead center after coasting. That is, it is stopped at the top dead center.

On the other hand, the incremental encoder 20 detects the crankshaft angle while being cleared to 0 by the top dead center detector 10 every time the main gear 1 passes through the top dead center, and compares the detected value with the comparison means.
Output to 40. The absolute value of the crankshaft angle is also input to the comparison means 40 from the absolute encoder 30.

Therefore, when the absolute encoder 30 is normal, both crankshaft angles have the same value.

If there is a difference in both crankshaft angles, the comparison means 40
Emits an abnormal signal ε.

It is understood that this abnormal signal ε uniquely detects the failure of the absolute encoder 30.

In addition, the abnormal signal ε is the absolute encoder
It is also possible to detect that 30 is normal and the incremental encoder 20 has failed. In this case the comparison means
The setting of 40, that is, the window of the comparator may be set bidirectionally.

If a buzzer or the like is sounded by this abnormal signal ε, it is possible to know the abnormal motion.

In this embodiment, the abnormal signal ε is input to the switching circuit 7 to operate the clutch brake 7.
Therefore, as shown in FIG. 2, the brake is applied after the set crankshaft angle θ1 by the angle θ. Therefore, the slide is stopped at α + θ degrees from the top dead center because the coasting distance is constant at −Spm.

In other words, the slide can be stopped only by positioning by the angle corresponding to the resolution of the incremental encoder 20 (pitch of 4.5 degrees in this embodiment).

Therefore, after passing through the top dead center, the top dead center proximity switch detects an error in the absolute encoder 30,
According to the conventional method of braking after that, the second
As shown by the dotted line in the figure, it crosses bottom dead center. However, the present invention can completely avoid such a situation as described above.

At the same time, the detected crankshaft angles are input to the brake operation confirmation means 50 from the incremental encoder 20 and the absolute encoder 30, respectively. Here, the braking operation confirming means 50 determines that the braking operation is normal when the rate of change of the crankshaft angle input after passing through the set crankshaft angle is rapidly decreasing. This is supposed to be notified by lighting a lamp or a buzzer. If the rate of change is constant, it is determined to be abnormal.

Therefore, according to this embodiment, the comparing means 40 compares the crankshaft angle by the absolute encoder 30 with the crankshaft angle by the incremental encoder 20, and if there is a difference between them, the abnormal signal ε Since it is configured to output, the failure of the absolute encoder 30 can be detected quickly and accurately, and smooth and reliable motion monitoring can be achieved with a smooth motion monitor.

Further, since the brake operation confirmation means 50 for confirming the brake operation from the change rate of the output signal of the absolute type encoder 30 or the incremental type encoder 20 is provided, it is possible to know in advance whether it is a normal motion or not. Is.

Further, since the failure of the absolute encoder 30 is detected by using the low cost incremental encoder 20, it is very economical.

In addition, the incremental encoder 20 is separate from the drive system (4,5) of the absolute encoder 30 and is configured to perform counting and zero clear with the reliable involvement of the main gear 1. The sex can be further enhanced.

Further, since the incremental encoder 20 is of a type that counts the number of teeth of the main gear 1, it is possible to detect an abnormality in a short time corresponding to the tooth pitch.

Further, since the abnormal signal ε instantaneously detected and output by the comparison means 40 is input to the switching circuit 7 to perform the braking operation, even if the absolute encoder 30 fails, the slide can be performed by coasting. It does not pass through bottom dead center and completely eliminates inconveniences such as double hits, and can smoothly operate high-speed and ultra-high-speed presses of 400 to 1,000 Spm.

[Effects of the Invention] As is apparent from the above description, the present invention provides an incremental encoder associated with the teeth of the main gear, and compares the crankshaft angles of this encoder and the absolute encoder with a comparison means. An error signal is generated based on the difference, and a brake operation confirmation unit that confirms the brake operation from the rate of change of the crankshaft angle is provided.Therefore, an absolute encoder error is detected in a short time equivalent to the main gear tooth pitch. it can. Further, since the incremental encoder counts and clears to zero due to the mechanically highly reliable teeth of the main gear, abnormalities can be detected with high reliability and accuracy. Further, it is economical because a failure of the absolute encoder is detected by using a low-cost incremental encoder. Further, it is possible to know in advance whether or not the brake operation that can reliably stop the slide at the top dead center has been performed. Therefore, a smooth and reliable motion monitor can be performed. In addition, this makes it possible to make high-speed and ultra-high-speed press machines safe, reliable, low cost, and convenient to handle.
It has an excellent effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram for similarly explaining the operation, and FIG. 3 (A),
(B) is a diagram for explaining the operation of a conventional motion monitor device, (A) is a general press machine, and (B) is a high-speed press machine. 1 ... Main gear, 7 ... Switching circuit, 9 ... Cam mechanism, 10 ... Top dead center detector, 20 ... Incremental encoder, 21 ... Detecting unit, 22 ... Detecting circuit, 30 ... Absolute Method encoder, 40 …… Comparison means, 50 …… Brake operation confirmation means.

Claims (1)

[Claims] 1. A press machine having an absolute encoder that detects an absolute angle of a crankshaft angle and outputs a press stop signal at a set crankshaft angle, in order to detect a top dead center of a slide by engaging with a cam mechanism. A dead center detector, an incremental encoder formed to count the number of teeth of the main gear to detect a crankshaft angle and to be zero-cleared by an output signal of the top dead center detector; and the absolute encoder. Comparing means for outputting the abnormal signal when there is a difference between the crankshaft angle detected by the incremental encoder and the crankshaft angle detected by the incremental encoder, and the press stop signal or the abnormal signal is output. Of the crankshaft angle detected by at least one of the two encoders Is a motion monitoring device for a press machine, which comprises a brake operation confirming unit that determines that the brake operation is normal when the value decreases at a predetermined rate and determines that the brake operation is abnormal when the value is constant.