Source: http://www.google.com/patents/US6334077?dq=6721967
Timestamp: 2017-02-21 14:52:30
Document Index: 10981322

Matched Legal Cases: ['art 60', 'art 70', 'art 60', 'art 70', 'art 60', 'art 60']

Patent US6334077 - Operation apparatus for press - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsThe present invention provides an operation apparatus for a press, of simple structure with lower cost. The operation apparatus for a press according to the present invention comprises a controlling system 1 for generating a slide actuation command signal K1 by an ON operation of an operation button...http://www.google.com/patents/US6334077?utm_source=gb-gplus-sharePatent US6334077 - Operation apparatus for pressAdvanced Patent SearchTry the new Google Patents, with machine-classified Google Scholar results, and Japanese and South Korean patents.Publication numberUS6334077 B1Publication typeGrantApplication numberUS 09/156,688Publication dateDec 25, 2001Filing dateSep 18, 1998Priority dateSep 19, 1997Fee statusLapsedPublication number09156688, 156688, US 6334077 B1, US 6334077B1, US-B1-6334077, US6334077 B1, US6334077B1InventorsKoichi Futsuhara, Masayoshi Sakai, Iwashige Takahashi, Yukio HataOriginal AssigneeThe Nippon Signal Co., Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (13), Referenced by (6), Classifications (13), Legal Events (9) External Links: USPTO, USPTO Assignment, EspacenetOperation apparatus for press
US 6334077 B1Abstract
The present invention provides an operation apparatus for a press, of simple structure with lower cost. The operation apparatus for a press according to the present invention comprises a controlling system 1 for generating a slide actuation command signal K1 by an ON operation of an operation button or an entrance/escape detection output of a human body by a light-beam type safety apparatus and controlling slide actuation, based on a crank angle signal from an encoder 4; a monitoring system 2 for monitoring controlling operation of the controlling system 1, including slide overrun monitoring function and the like, utilizing operation button ON signal T, operation button-OFF signal /T or the detection output from the light-beam type safety apparatus, position signals Pa and Pb indicative of slide elevating process and slide lowering process, respectively, position signal Ph from a light-beam type safety apparatus, and slide actuation command OFF signal /K1; and an AND gate 3 for generating a slide actuation signal S based on the slide actuation command signal K1 from the controlling system 1, only when the normality judgment signals K2, K3 are being generated from the monitoring system 2. Images(12) Claims(20)
What we claimed are: 1. An operation apparatus for a press, comprising:
a controlling system for generating a slide actuation command signal to control actuating and stopping of a slide such that said slide actuation command signal is stopped at a predetermined timing; a monitoring system separate from said controlling system for determining whether said controlling system is operating normally and for generating a slide actuation permission signal if said controlling system is operating normally; and actuation signal generation means for generating a slide actuation signal based on input of said slide actuation command signal from said controlling system, wherein the slide actuation signal is generated only when said actuation signal generation means is input with said slide actuation permission signal from said monitoring system. 2. An operation apparatus for a press of claim 1, wherein said controlling system generates said slide actuation command signal based on an operation button ON operation by an operator, and stops said slide actuation command signal after the slide has transferred from a lowering process to a elevating process.
12. An operation apparatus for a press of claim 1, wherein said monitoring system is constituted in a fail-safe manner such that: said monitoring system generates said slide actuation permission signal having logical value “1” when judging that said controlling system is normal; and said slide actuation permission signal becomes logical value “0” when said controlling system is abnormal or when said monitoring system itself fails.
first monitoring means comprising: a first OR circuit for calculating logical sum of a first position signal and an output signal of a light-beam type safety apparatus, said first position signal being output from position signal generating means which generates said first position signal which becomes logical value “1” when the slide is in the elevating process, and a second position signal which becomes logical value “1” when the slide is in the lowering process; and a first self-hold circuit having an output of said first OR circuit as a hold input thereof, and an operation button ON signal which becomes logical value “1” by an operation button ON operation as a trigger input thereof, said first self-hold circuit being adapted to self-hold said trigger input; second monitoring means comprising: a first AND circuit for calculating logical product of said first position signal and said operation button ON signal; a second self-hold circuit having said first position signal as a hold input thereof and an operation button OFF signal which becomes logical value “1” by an operation button OFF operation as a trigger input thereof, said second self-hold circuit being adapted to self hold said trigger input; a third self-hold circuit having said first position signal as a hold input thereof and a slide actuation command OFF signal which becomes logical value “1” when said slide actuation command signal of said controlling system is stopped as a trigger input thereof, said third self-hold circuit being adapted to self hold said trigger input; and a second AND circuit for calculating logical product of the outputs of said first AND circuit and said second and third self-hold circuits; a fourth self-hold circuit having said second position signal as a hold input thereof and an output of said second AND circuit as a trigger input thereof, and for self holding said trigger input; and a second OR circuit for calculating logical sum of an output of said fourth self-hold circuit and said first position signal; and wherein said outputs of said first self-hold circuit and said second OR circuit are input, as said slide actuation permission signal, into said actuation signal generation means. 14. An operation apparatus for a press of claim 13, wherein said first self-hold circuit of said first monitoring means has a leading-edge differential signal of said operation button ON signal as a trigger input thereof, said first AND circuit of said second monitoring means calculates logical product of said first position signal and said leading-edge differential signal of said operation button-ON signal, and said second self-hold circuit is omitted from said second monitoring means.
first monitoring part comprising: a third AND circuit for calculating logical product of outputs of said first AND circuit and said second self-hold circuit; and a first flip-flop circuit having an output of said third AND circuit as a set input and a leading-edge differential signal of said first position signal as a reset input; a second monitoring part comprising a second flip-flop circuit having said slide actuation command OFF signal as a set input and input with a leading-edge differential signal of said first position signal as a reset input; a first oscillating means which oscillates when said first flip-flop circuit is reset; a second oscillating means which oscillates when said first flip-flop circuit is set; a third oscillating means which oscillates when said second flip-flop circuit is reset; a fourth oscillating means which oscillates when said second flip-flop circuit is set; a fourth AND circuit for calculating logical product of the outputs of said second and fourth oscillating means; a fifth AND circuit for calculating logical product of outputs of said first and third oscillating means and an output of said first position signal; and a third OR circuit for calculating logical sum of outputs of said fourth and fifth AND circuits; and wherein the outputs of said first self-hold circuit and said third OR circuit are input, as said slide actuation permission signal, into said actuation signal generation means. 16. An operation apparatus for a press of claim 13, wherein said monitoring system comprises, instead of said second monitoring means, said fourth self-hold circuit and said second OR circuit:
third monitoring part comprising: a fifth self-hold circuit; a sixth AND circuit for calculating logical product of outputs of said first AND circuit and said second and fifth self-hold circuits; and a third flip-flop circuit having an output of said sixth AND circuit as a set input and a leading-edge differential signal of said slide actuation command OFF signal as a reset input; a fifth oscillating means which oscillates when said third flip-flop circuit is reset; a sixth oscillating means which oscillates when said third flip-flop circuit is set; and a fourth OR circuit for calculating logical sum of an output of said sixth oscillating means and said first position signal; and wherein said fifth self-hold circuit has said first position signal as a hold input and the output of said fifth oscillating means as a trigger input, and self-holds said trigger input, and the outputs of said first self-hold circuit and said fourth OR circuit are input, as said slide actuation permission signal, into said actuation signal generation means. 17. An operation apparatus for a press of claim 13, wherein said position signal generating means is constituted such that said first position signal becomes logical value “1” in a crank angle range of from a bottom dead center to a predetermined angle after a top dead center, and said second position signal becomes logical value “1” in a crank angle range of from the predetermined angle after the top dead center to the bottom dead center.
third monitoring means comprising: a fifth OR circuit for calculating logical sum of a first position signal and an output signal of a light-beam type safety apparatus, said first position signal being output from position signal generating means which generates said first position signal which becomes logical value “1” when the slide is in the elevating process, and a second position signal which becomes logical value “1” when the slide is in the lowering process which includes a slide elevating process just before the transference to the lowering process of slide; a seventh AND circuit for calculating logical product of a leading-edge differential signal of operation button ON signal and said second position signal; and a sixth self-hold circuit having an output of said fifth OR circuit as a hold input thereof, and an output of said seventh AND circuit as a trigger input thereof, said sixth self-hold circuit being adapted to self-hold said trigger input; fourth monitoring means comprising: an eighth AND circuit for calculating logical product of said first and second position signals and a leading-edge differential signal of said operation button ON signal; a seventh self-hold circuit having said first position signal as a hold input thereof and an operation button OFF signal which becomes logical value “1” by an operation button OFF operation as a trigger input thereof, said seventh self-hold circuit being adapted to self hold said trigger input; an eighth self-hold circuit having said first position signal as a hold input thereof and a slide actuation command OFF signal which becomes logical value “1” when said slide actuation command signal of said controlling system is stopped as a trigger input thereof, said eighth self-hold circuit being adapted to self hold said trigger input; and a ninth AND circuit for calculating logical product of the outputs of said eighth AND circuit and said seventh and eighth self-hold circuits; fifth monitoring means comprising: an adding circuit for adding output levels of said first and second position signals; a window comparator for threshold-value calculating an added output level of said adding circuit to thereby generate an output only when said added output level corresponds to logical value “1” ; and a sixth OR circuit for calculating an logical sum of an output of said window comparator and the output of said eighth self-hold circuit of said fourth monitoring means; a ninth self-hold circuit which has said second position signal as a hold input thereof and an output of said ninth AND circuit of said fourth monitoring means as a trigger input thereof, and self holds said trigger input; and a seventh OR circuit for calculating logical sum of an output of said ninth self-hold circuit and said first position signal; and wherein said outputs of said sixth self-hold circuit and said sixth and seventh OR circuits are input, as said slide actuation permission signal, into said actuation signal generation means. 20. An operation apparatus for a press of claim 18, wherein said position signal generating means is constituted such that said first position signal becomes logical value “1” in a crank angle range of from a bottom dead center to a predetermined angle after a top dead center, and said second position signal becomes logical value “1” in a crank angle range of from the predetermined angle before the top dead center to the bottom dead center.
The signal P1 has logical value “1” within a range where the crank angle θ is from 340° to 15° and this range represents a range where the slide is to stop. Namely, the signal P1 is for confirming as to whether the slide, after its automatic elevation, has stopped by the crank angle 15°.
The signal P2 has logical value “1” within a range where the crank angle θ is from 345° to 300°, and this signal P2 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 P2 has just become logical value “0”, the slide elevation should be stopped.
The signal P3 has logical value “1” within a range where the crank angle θ is from 180° (bottom dead center) to 350°, and this signal P3 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 P2. Namely, the actual elevation permission range for the slide is the range (from 180° to 300°) in which both of signals P2 and P3 have logical value “1”.
The signal P4 has logical value “1” within a range where the crank angle θ is from 270° to 240°, and this signal P4 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.
If the monitoring system is constituted in a fail-safe manner such that: the monitoring system generates an output of logical value “1” when judging that the controlling system is normal; and an output of logical value “0” when judging that the controlling system is abnormal or when the monitoring system itself fails; the slide actuation is never conducted in case of failure of the monitoring system, so that the safety and reliability can be further enhanced.
The controlling system 1 is constituted such as of: an encoder 4 for detecting the rotational angle of a crank which drives the slide; and a controlling circuit 5, which is constituted such as of a microcomputer, for controlling generation/stopping of a slide actuation command signal K1, based on a crank-angle signal (slide position signal) from the encoder 4 and an ON/OFF signal from the operation button (in the drawings, “T” and “/T” indicate ON signal and OFF signal, respectively). To calibrate the slide position signal of the encoder 4, the controlling circuit 5 is also input with slide position signals Pa and Pb from a position signal generating apparatus 40 functioning as position signal generating device, which is to be later shown in FIG. 2 and detects previously set predetermined positions (15° and 180°, in terms of crank angle) of the slide.
The monitoring system 2 includes a re-activation prevention function (function to prevent the actuation of the slide insofar as the operation button is not operated by the operator after the slide has been once stopped). Further, the monitoring system 2 comprises: a first monitoring circuit 10 having a function as first monitoring device for monitoring the safety at the slide lowering, based on an output signal Ph from a light-beam type safety apparatus (not shown) to be arranged at the danger-zone boundary part in front of a bolster, to thereby confirm the safety within the danger zone including the bolster; a second monitoring circuit 20 having a function as second monitoring device which includes monitoring functions such as an overrun monitoring function for confirming that the slide has stopped within the crank angle 15° (slide elevating process), a monitoring function for monitoring OFF of the operation button during the slide elevating process, and a monitoring function (monitoring function of automatic slide elevation OFF) for monitoring that a slide actuation command signal K1 is turned OFF in the slide elevating process; a fourth self-hold circuit 30 functioning as signal resetting device for memorizing and holding a monitoring-result output (logical value “1”) indicative of normality, output from the second monitoring circuit 20 in the slide lowering process, and for resetting this monitoring result output in the slide elevating process; and an OR gate 31 which is a second OR circuit for calculating logical sum of an output of the fourth self-hold circuit 30 and the position signal Pa which becomes logical value “1” in the slide elevating process.
The ON signal T and OFF signal /T of the operation button can be generated such as based on an operation button signal generating circuit described in U.S. Pat. No. 5,285,721 mentioned above, or based on Japanese Unexamined Patent Publication No. 6-84088. Such an operation button signal generating circuit is provided for the operation button having an ON contact of which contact point closes at the ON operation and an OFF contact of which contact point closes by spring-returning after ON operation; and each of the ON signal T and OFF signal /T of the operation button are output as logical value “1”, by level testing the outputs from such contact points making use of associated window comparators, respectively. These ON signal T and OFF signal /T of the operation button are dual signals which never have logical value “1” simultaneously with each other.
The slide actuation command OFF signal /K1 can be obtained by adopting an output of a current-zero detecting sensor conventionally known such as from U.S. Pat. No. 5,345,138, in which: the sensor detects the presence/absence of electric current in an output line of the slide actuation command signal K1 of controlling circuit 5, and generates an output having logical value “1” in the absence of current (corresponding to actuation command OFF) and logical value “0” in the presence of flowing current.
In FIG. 2, two disks 42, 43 are fixed to a crankshaft 41 connected to the slide. One disk 42 is formed with, near the periphery thereof, a slit 42A from a bottom dead center (180°) of crank angle to a predetermined angle after a top dead center (0°), such as, over a crank angle range from 180° to 15° (slide elevating process), and the other disk 43 is formed with, near the periphery thereof, a slit 43A from the predetermined angle after the top dead center to the bottom dead center, in this case over a crank angle range from 15° to 180° (slide lowering process). Further, there are provided photo-interrupters 45 and 46 for the moving loci of the slits 42A and 43A, respectively, each of which has a light emitting element and a light receiving element facing each other across one of disks 42 and 43. By such a constitution, as the crankshaft 41 rotates: in the range of crank angle from 180° to 15°, there is generated the first position signal Pa having logical value “1” from the photo-interrupter 45 by the fact that the light receiving element of photo-interrupter 45 receives the light from the light emitting element of photo-interrupter 45 via slit 42A; and in the range of crank angle from 15° to 180°, there is generated the second position signal Pb having logical value “1” from the photo-interrupter 46 by the fact that the light receiving element of photo-interrupter 46 receives the light from the light emitting element of photo-interrupter 46 via slit 43A. Namely, in this embodiment, as shown in FIG. 3, the crank angle range from 180° to 15° is assumed to be the slide elevating process so that the position signal Pa=“1” is generated, and the crank angle range from 15° to 180° is assumed to be the slide lowering process so that the position signal Pb=“1” is generated. In this case, there is frequently used in a fail-safe processing for a signal, such a method that the light signal from light emitting element is formed of alternating current light beam which is received by the light receiving element, and the alternating current light receiving signal from the light receiving element is rectified to obtain a binary value signal (logical value “1” and logical value “0”) (see, for example, U.S. Pat. No. 5,345,138).
When the operator has turned ON the operation button so that the ON signal T of operation button is input, the slide actuation command signal K1 is generated by the controlling circuit 5. If the press is normal, all of the output signals K2 and K3 from the monitoring system 2 become to have logical value “1”. Thus, the generation of slide actuation command signal K1 from the controlling circuit 5 causes a slide actuation signal S to be generated from the AND gate 3, so that the slide starts lowering.
When the slide has passed through the crank angle 15° to thereby enter the lowering process, the position signal Pa disappears. Instead, there is generated the slide position signal Pb having logical value “1” indicative of the slide lowering process. By the generation of this slide position signal Pb, the output of logical value “1” from the AND gate 24 input into the self-hold circuit 30 is held during the lowering process. As such, the output signal K3 of the OR gate 31 is held at logical value “1”. Further, if the safety of bolster is guaranteed in the slide lowering process, the monitoring signal K2 of first monitoring circuit 10 is held at logical value “1”, by the output signal Ph from the light-beam type safety apparatus. Thus, the slide actuation signal S is kept generated during the lowering process, so that the lowering operation is continued. Further, by the disappearance of the position signal Pa, all of the outputs of AND gate 21 and self-hold circuits 22, 23 disappear, so that the overrun monitoring result, OFF confirmation of operation button, and confirmation of actuation command stop are reset, resulting in resetting of all of the monitoring results by the second monitoring circuit 20.
When the slide has passed through the bottom dead center (crank angle 180°) to enter the elevating process, the slide position signal Pb from the photo-interrupter 46 disappears so that the output of the self-hold circuit 30 disappears. At this time, however, there is generated the position signal Pa of logical value “1” from the photo-interrupter 45, so that the output signal K3 of OR gate 31 is kept unchanged, at logical value “1”. Thereafter, when the slide actuation command signal K1 of controlling circuit 5 is normally stopped, the slide actuation command OFF signal /K1 is generated and the OFF signal /T of operation button is generated, in the slide elevating process in which the position signal Pa has logical value “1”, the monitoring outputs having logical value “1” from the self-hold circuits 22, 23 are generated again and held until disappearance of the position signal Pa (i.e., until transference to the slide lowering process). Then, if the brake performance is normal, the slide is stopped within a range of crank angle 15° and the position signal Pa is kept at logical value “1”.
Under this condition, when the operator turns ON the operation button for the next slide actuation to thereby generate the operation button ON signal T, the overrunning monitoring output from the AND gate 21 becomes logical value “1” indicative of normality, since the position signal Pa has logical value “1”. As a result of the above, there is generated an output of logical value “1” from the AND gate 24. Further, at the time the slide enters the lowering process, the output of logical value “1” of AND gate 24 is memorized and held by the self-hold circuit 30, by virtue of the output of slide position signal Pb having logical value “1”, so that an output of logical value “1” is generated from the self-hold circuit 30.
As described above, the output signal K3 of the OR gate 31 continuously keeps logical value “1” insofar as the press is normally operating, and the monitoring signal K2 of the first monitoring circuit 10 also continuously keeps logical value “1” insofar as the safety at the time of slide lowering is guaranteed. As such, the slide operation can be executed, whenever the slide actuation command signal K1 is generated from the controlling circuit 5 based on the operation of operation button by the operator. Further, those output signals of overrun monitoring of slide, OFF confirmation of operation button, and OFF confirmation of actuation command are reset by transference to the elevating process of slide, and are confirmed at each cycle of the slide.
In the circuit of FIG. 1, if the slide actuation command signal was not turned OFF such as by failure of controlling circuit 5, the monitoring output of self-hold circuit 23 never becomes to have logical value “1”. Further, the monitoring output of second self-hold circuit 22 does not become logical value “1”, unless the operation button is turned OFF. In addition, such as due to deterioration of brake performance, if the slide has overrun the crank angle 15° and stopped beyond the same irrespectively of the fact that the actuation command and operation button have been normally turned OFF, the output of logical value “1” of position signal Pa will disappear. In this case, the output of AND gate 21 does not become logical value “1”, even if the operation button is turned ON. Thus, in such an abnormal condition, the monitoring output of second monitoring circuit 20 (i.e., output of AND gate 21) never becomes logical value “1”, so that the slide actuation signal S is never generated. Also during the slide lowering, when the output signal Ph of light-beam type safety apparatus has become logical value “0” by detecting a foreign matter, the output signal K2 of first monitoring circuit 10 becomes logical value “0” so that the slide actuation signal S is immediately stopped to thereby stop the slide lowering. In case that the slide is stopped during the slide lowering, the output signal K2 of first monitoring circuit 10 does not become logical value “1” unless the operation button ON signal T is generated by the ON operation of operation button by the operator, so that the slide can not be actuated.
Moreover, the monitoring system is constituted in such a fail-safe manner that its output becomes logical value “0” in case of failure. Thus, when abnormality has occurred even in the monitoring system itself, the slide actuation is forcibly stopped so that the operation apparatus for press is made to be extremely superior in safety.
The monitoring part 60 comprises: an AND gate 61 which is a third AND circuit for calculating logical product of the output of AND gate 21 which generates the monitoring output of overrunning and the output of second self-hold circuit 22 which generates the operation button OFF monitoring output; and a first flip-flop circuit 62 (hereinafter referred to as first F/F circuit) having the output of AND gate 61 as a set input thereof and a leading-edge differential signal (dPa/dt>0) of the position signal Pa indicative of the elevating process of slide as a reset input thereof. C1 is a capacitor.
The monitoring part 70 comprises a second F/F circuit 71 having the slide actuation command OFF signal /K1 as a set input thereof and a leading-edge differential signal (dPa/dt>0) of the position signal Pa indicative of the elevating process of slide as a reset input thereof. C2 is a capacitor.
When the slide has transferred from the lowering process to the elevating process, there is generated the position signal Pa having logical value “1” to thereby reset the F/F circuits 62 and 71. Thereafter, the F/F circuit 62 in the monitoring part 60 is set, when the output of AND gate 61 becomes logical value “1” by the generation of the operation button OFF signal /T and operation button ON signal T. When an output of high-level is generated by setting the F/F circuit 62, the oscillator OSC2 generates an output. Meanwhile, when the slide actuation command OFF signal /K1 is generated, the F/F circuit 71 in the monitoring part 70 is set, so that the oscillator OSC4 generates an output. Accordingly, if the press is normally operating, an output of AND gate 80 becomes logical value “1”, by the rectified outputs from the oscillators OSC2, OSC4 based on the set outputs from the F/F circuits 62 and 71, so that an output signal K3 of OR gate 82 becomes logical value “1”. Thus, with generation of the slide actuation command signal K1 from the controlling system, the slide actuation signal S is generated via AND gate 3, since the output signal K2 of the first monitoring circuit 10 shown in the first embodiment has logical value “1” insofar as the safety in the danger zone is guaranteed. Further, when the F/F circuits 62 and 71 are reset by the generation of the position signal Pa due to transference of the slide to the elevating process, there are generated outputs from the oscillators OSC1, OSC3, respectively, so that the output of AND gate 81 becomes logical value “1”, resulting in that the output of OR gate 82 is kept at logical value “1”.
In the circuit of FIG. 4, the F/F circuit 71 is not set, when the slide actuation command signal K, is not turned OFF after the F/F circuits 62 and 71 have been normally reset. Further, the output of AND gate 61 does not become logical value “1” and therefore the F/F circuit 62 is not set, such as in case that the operation button has not been turned OFF or that the slide has overrun the crank angle 15° and stopped at a position beyond the same. In such a situation, the output signal K3 of OR gate 82 disappears, so that the slide actuation signal S is not generated.
In FIG. 5, a monitoring part 60′ as a third monitoring part of this embodiment includes the AND gate 21 and self-hold circuit 22 so as to have a function same as that of the monitoring part 60 of FIG. 4. However, its constitution additionally includes a fifth self-hold circuit 63 having a trigger input terminal to which the output of the oscillator OSC1 functioning as fifth oscillating device is input, and a hold input terminal to which the position signal Pa is input, so that this circuit 63 memorizes and holds, during the slide elevating process, that a F/F circuit 62′ has been reset. The output signal of this fifth self-hold circuit 63 is input to an AND gate 61′ which is a sixth AND circuit. Further, the F/F circuit 62′ as a third F/F circuit is constituted to be reset by a leading-edge differential signal of the slide actuation command OFF signal /K1. Yet further, an OR gate 82′, which is a fourth OR circuit, generates the output signal K3 by calculating logical sum of the output of oscillator OSC2 functioning as sixth oscillating device, and the position signal Pa. The self-hold circuit 63 has a fail-safe constitution identical with that of the self-hold circuit 22. C3 is a capacitor. Similarly to FIG. 4, the controlling system 1 and the first monitoring circuit 10 having the re-activation prevention function and monitoring the safety at the time of slide lowering are identical with those of the first embodiment, so that they are omitted.
In such a constitution, upon generation of the slide actuation command OFF signal /K1 by the transference of slide into the elevating process, the leading-edge differential signal thereof resets the F/F circuit 62′. Then, the output x is generated from the oscillator OSC1, and is memorized and held by the self-hold circuit 63 during the slide elevating process and input into the AND gate 61′. Thus, the output of AND gate 61′ becomes logical value “1” to thereby set the F/F circuit 62′, only when the generation of the slide actuation command OFF signal /K1 is confirmed, operation button OFF is confirmed by the output of the self-hold circuit 22 and the slide has not overrun so that the operation button is turned ON under an appropriate condition of the brake performance. As a result, the output signal K3 having logical value “1” is input into the AND gate 3 via oscillator OSC2 and OR gate 82′, so that the slide actuation is enabled.
In FIG. 7, the monitoring circuit 91 includes, in addition to the OR gate 11 functioning as the fifth OR circuit of FIG. 1 and a sixth self-hold circuit 12′, an AND gate 13 which is a seventh AND circuit for performing a logical-product calculation of a leading-edge signal of operation button ON signal T and the position signal Pb′ indicative of slide lowering process in which the output of the AND gate 13 is input into a trigger input terminal of a sixth self-hold circuit 12′. C4 is a capacitor for detecting a leading edge of the ON signal of operation button.
The monitoring circuit 92 is constituted of: an AND gate 21′ which is an eighth AND circuit; self-hold circuits 22, 23 functioning as seventh and eighth self-hold circuits; and an AND gate 24′ which is a ninth AND circuit. The AND gate 21′ is additionally input with the position signal Pb′ indicative of the slide lowering process. C5 is a capacitor for detecting a leading edge of the ON signal T of operation button.
The monitoring circuit 93 is constituted of: an adding circuit 96 for adding the position signal Pa indicative of slide elevating process and the position signal Pb′ indicative of slide lowering process; a fail-safe window comparator 97 for threshold-value calculating the output of the adding circuit 96; and an OR gate 98 which is a sixth OR circuit for calculating logical sum of the output of window comparator 97 and the output of self-hold circuit 23 of monitoring circuit 92; in which the output signal K4 of OR gate 98 is input to the AND gate 3.
In case of this embodiment, the output range of logical value “1” of the position signal Pb′ indicative of the slide lowering process is widened up to a predetermined angle before the top dead center (0°), such as to a crank angle 345°, such that the slide actuation signal OFF can be confirmed before the maximum crank angle 345°, as shown in FIG. 8. Thus, in this embodiment, both of the position signal Pa indicative of slide elevating process and the position signal Pb′ indicative of slide lowering process have logical value “1”, in the crank angle range from 345° to 15°.
As such, the adding circuit 96 of monitoring circuit 93 generates an output having a level corresponding to logical value “2” when both of position signals Pa and Pb′ have logical value “1”, generates an output of logical value “1” when only one of them has logical value “1”, and generates an output having a level corresponding to logical value “0” when both of them have logical value “0”. Further, the window comparator 97 generates an output of logical value “1” only when the output of adding circuit 96 has logical value “1” and an output of logical value “0” when the output of adding circuit 96 has logical value “2” or logical value “0”. Such a fail-safe window comparator is known such as from the aforementioned U.S. Pat. No. 5,345,138, and International Unexamined Patent Publication WO 94/23303.
In the monitoring circuit 93, the output of window comparator 97 becomes to have logical value “0”, when both position signals Pa and Pb′ become logical value “1”. Namely, the output of window comparator 97 becomes to have logical value “0”, after the slide has passed over the crank angle 345° in the slide elevating process. Thus, when the slide actuation command OFF signal /K1 can be confirmed before the crank angle 345°, the output signal K4 of OR gate 98 is held at logical value “1” even after the crank angle 345°, by the output of self-hold circuit 23 of monitoring circuit 92. However, when the generation of slide actuation command OFF signal /K1 has not been confirmed by the time that the slide passes over the crank angle 345°, the output signal K4 of OR gate 98 becomes logical value “0”, thereby causing the slide actuation signal S to disappear so that the slide actuation is stopped.
In FIG. 11, a direction detecting circuit 110 comprises: a NOT circuit 111 for NOT operating an output signal B1 of optical curtain 103; a NOT circuit 112 for NOT operating an output signal B2 of optical curtain 104; a self-hold circuit 113 with an output of NOT circuit 111 as a trigger input signal, and with an output of NOT circuit 112 as a hold input; an AND gate 114 for calculating logical product of the output signal B1 of optical curtain 103 and the output signal of self-hold circuit 113; and a self-hold circuit 115 with an output of AND gate 114 as a trigger input and with the output signal B2 of optical curtain 104 as a hold input; in which the output of logical value “1” of this self-hold circuit 115 is made an escape confirmation signal.
When the operator carries in a work onto the bolster 105, the light axes LB2 of optical curtain 104 are firstly interrupted, and then the light axes LB1 of optical curtain 103 are interrupted. As such, the output signal B2 of optical curtain 104 firstly disappears (i.e., becomes logical value “0”) so that the output signal /B2 (indicative of negation of output signal B2) of NOT circuit 112 firstly becomes logical value “1”, and then the output signal B1 of optical curtain 103 disappears (i.e., becomes logical value “0”) so that the output signal /B1 (indicative of negation of output signal B1) of NOT circuit 111 becomes logical value “1”. At the time the output signal B2 of optical curtain 104 has disappeared, the output signal of self-hold circuit 115, i.e., an output signal B12 of direction detecting circuit 110, becomes logical value “0”, so that the operator's hand is judged to exist over the bolster 105. Further, at the time the output signal B1 of optical curtain 103 has disappeared, the self-hold circuit 113 is triggered by the output of logical value “1” from NOT circuit 111, so that one of inputs of AND gate 114 becomes logical value “1”.
When the operator's hand is drawn, the output signal B1 of optical curtain 103 firstly rises up to logical value “1”, and then the output signal B2 of optical curtain 104 rises up to logical value “1”. At the time the output signal B1 of optical curtain 103 has just risen up, the other input of AND gate 114 becomes logical value “1”, so that an output signal B0 of AND gate 114 becomes logical value “1”. Thereafter, when the output signal B2 of optical curtain 104 has risen up, the hold input of self-hold circuit 115 becomes logical value “1” causing the output signal B12 of self-hold circuit 115 to become logical value “1”, so that the operator's hand is judged to have escaped. In the above, the AND gate 114, and self-hold circuits 113, 115 are fail-safe constituted identically to the aforementioned embodiments. Also, the NOT circuits 111 and 112 are constituted to have the respective outputs of value “0” in case of failure, and can be realized making use of a fail-safe window comparator such as described in detail in the aforementioned U.S. Pat. No. 5,027,114.
In case that the operation apparatus for a press is provided in which the slide actuation is automatically conducted by detecting the movement of the operator's hand based on the output signal of such a light-beam type safety apparatus 100 in place of operation button, the output signal B12 of direction detecting circuit 110 in FIG. 11 is input, instead of an ON signal of operation button, into the controlling system 1 and the slide actuation command signal K1 is generated from the controlling system 1 when the output signal B12 having logical value “1” is input.
Further, as to the generation confirmation function for the operation button OFF signal /T, it is possible to obtain, such as by a circuit configuration shown in FIG. 13, an output signal of logical value “1” by detecting that the output signal B12 of direction detecting circuit 110 has fallen within a predetermined period of time after generation of the position signal Pa=1, under the condition that the operator is to carry in a work within the predetermined period of time after the slide has transferred from the lowering process to the elevating process.
In the circuit of FIG. 13, if the output signal B12 falls (generation of (dB12/dt)<0) due to a work-carry-in operation by the operator, within a delay time (corresponding to the aforementioned predetermined period of time) of an OFF-delay circuit 120 after the time point that the position signal Pa becomes “1” (Pa=1), an output of an AND gate 122 is caused to become logical value “1” by an output of a falling-edge detecting circuit 121, to thereby trigger a self-hold circuit 123 so that an output signal z of circuit 123 becomes logical value “1”. Contrary, if the work carry in operation has not been done within the aforementioned delay time of OFF-delay circuit 120, the output of OFF-delay circuit 120 disappears so that an output signal of logical value “1” is not generated from the AND gate 122, resulting in failure of triggering of the self-hold circuit 123.
Thus, as the operation button OFF confirmation signal in FIGS. 1, 4, 5 and 7, the output signal z of self-hold circuit 123 in FIG. 13 may be input into the AND gates 24 and 24′ of FIGS. 1 and 7, 61 and 61′ of FIGS. 4 and 5, respectively. Only, if this function is not required, this interlock may be omitted.
As to the overrun monitoring function in case of automatic operation under omission of operation button, the slide actuation command signal K1 may be input, instead of the operation button ON signal T, into each of AND gates 21, 21′ in FIGS. 1, 4, 5 and 7, since the slide actuation command signal K1 from controlling system 1 corresponds to the operation button ON. Further, the output signal B12 of direction detecting circuit 110 may be adopted instead of the slide actuation command signal K1.
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