Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1998-09-18
2001-12-25
Gordon, Paul P. (Department: 2786)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C100S048000, C100S348000
Reexamination Certificate
active
06334077
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an operation apparatus for a press, and particularly to an operation apparatus for a press in which simplification and cost reduction of the apparatus are achieved while ensuring a fail-safe characteristic.
2. Related Art of the Invention
In a system of a recent press, there has been provided such a safety function that a slide of the press (i.e., movable part of the machine side) can be automatically stopped if there occurs such a situation danger for an operator, and the operation of slide is permitted only when such a safety function is guaranteed to be normally operating. Examples of such conventional presses include one described in U.S. Pat. No. 5,285,721, which has been proposed by the present applicant.
In such a conventional operation system, there are used four signals P
1
to P
4
for indicating slide positions such as shown in
FIG. 15
, so as to realize the aforementioned safety function of the press. Namely, by utilizing these four signals P
1
to P
4
, it is monitored as to whether the slide, after its elevation, has stopped within a predetermined range near the top dead center or not (overrun monitoring function), in order to confirm the brake performance; and the actuation of slide is permitted only when the brake performance is confirmed to be normal. To monitor the overrun, it is confirmed as to whether an operation button is turned OFF during the slide elevating process (confirmation of operation button OFF). In the above, the signals P
1
to P
4
are indicated by the crank angles corresponding to respective slide positions.
The signal P
1
has logical value “1” within a range where the crank angle &thgr; is from 340° to 15° and this range represents a range where the slide is to stop. Namely, the signal P
1
is for confirming as to whether the slide, after its automatic elevation, has stopped by the crank angle 15°.
The signal P
2
has logical value “1” within a range where the crank angle &thgr; is from 345° to 300°, and this signal P
2
represents: a brake-performance-guaranteed lowering-motion-actuation starting point in case of slide lowering; and a range up to stoppage of automatic elevation of the slide. When this signal P
2
has just become logical value “0”, the slide elevation should be stopped.
The signal P
3
has logical value “1” within a range where the crank angle &thgr; is from 180° (bottom dead center) to 350°, and this signal P
3
represents a range of automatic elevation permission for the slide. In fact, the automatic elevation of slide is restricted at the crank angle of 300° represented by the signal P
2
. Namely, the actual elevation permission range for the slide is the range (from 180° to 300°) in which both of signals P
2
and P
3
have logical value “1”.
The signal P
4
has logical value “1” within a range where the crank angle &thgr; is from 270° to 240°, and this signal P
4
represents a range in which it is memorized and held that the operation button is turned OFF during the slide elevating process. When the operation button is turned OFF after passing over 270° in the elevating process, this OFF confirmation signal is memorized and held up to 240° in the next stroke.
Based on a generation state of such four signals P
1
to P
4
, the aforementioned overrun monitoring is performed for each one cycle of the slide operation, so that the safety at the time of slide actuation is guaranteed by assuming the brake performance normality to be a prerequisite for the next slide actuation. In the above, the monitoring result of overrunning is utilized as a data for judging that the brake performance was normal at the last operation, even when the slide is stopped during slide lowering process. As such, it is required to memorize the monitoring result until just before this result is reconfirmed in the slide elevating process. Thus, in the aforementioned conventional apparatus, there is used a fail-safe self-hold circuit for memorizing the monitoring result.
However, the aforementioned conventional operation apparatus for a press is constituted such that a part of the slide position signals for monitoring is utilized as information for controlling. As such, there is not separation between the controlling system for executing the operation control such as actuation/stopping of slide and the monitoring system for monitoring the functions for ensuring safety, and rather, the monitoring system is integrally incorporated into the controlling system. Thus, not only the monitoring system but also the whole of controlling system have been required to be constituted in a fail-safe manner, causing that the number of required slide position signals becomes numerous so that the constitution of controlling system is complicated.
SUMMARY OF THE INVENTION
The present invention has been carried out in view of the conventional problems as described above, and it is therefore an object of the present invention to provide an operation apparatus for a press, in which simplification and cost reduction of the apparatus are achieved by separating the controlling system and the monitoring system.
To this end, the operation apparatus for a press according to the present invention is constituted to comprise: a controlling system for generating a slide actuation command signal, and controlling actuation/stopping of a slide such that the slide actuation command signal is stopped at a predetermined timing; a monitoring system for monitoring as to whether the actuation/stopping controlling by the controlling system is normal or not, and for generating a slide actuation permission signal if normal; and an actuation signal generation device for generating a slide actuation signal based on input of the slide actuation command signal from the controlling system, only when the actuation signal generation device is input with the slide actuation permission signal from the monitoring system.
According to such a constitution, the controlling system and monitoring system can be constituted in a separated manner such that the controlling system controls the slide actuation/stopping of the press, while the monitoring system monitors as to whether the controlling operation of the controlling system is normal or not.
Concretely, the controlling system generates a slide actuation command signal based on an operation button ON operation by an operator, and stops the slide actuation command signal after the slide has transferred from a lowering process to an elevating process.
In such a constitution that the slide actuation command signal is generated based on the operation button ON operation, the monitoring system comprises: an actuation command OFF confirmation device for confirming as to whether or not the slide actuation command signal from the controlling system is stopped in the slide elevating process; and an operation button OFF confirmation device for confirming as to whether or not the operation button is turned OFF in the slide elevating process; and a logical product output of both confirmation devices is input, as the slide actuation permission signal, into the actuation signal generation device. Further, in addition to both confirmation devices, the monitoring system may further comprise an overrun confirmation device for confirming as to whether the slide is stopped within a predetermined range near the top dead center at the time of operation button ON operation.
According to such a constitution, there is generated a controlling actuation permission signal from the monitoring system when the operation button is turned OFF and the slide actuation command is turned OFF in the slide elevating process. Further, the slide actuation permission signal is generated from the monitoring system, by judging that the brake performance is normal, when it is confirmed that the slide has stopped near the top dead center.
The monitoring system may comprise: an overrun confirmation device for confirming as to whether or not the slide is stopping within a range of elevating process at the time a slid
Futsuhara Koichi
Hata Yukio
Sakai Masayoshi
Takahashi Iwashige
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Gordon Paul P.
The Nippon Signal Co. Ltd.
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