JPH0374701A - Detection device for working of interlocking circuit of injection molding machine safety device - Google Patents

Abstract

PURPOSE:To individually and directly detect the working state of plural limit switches irrespective of the fitting places of the limit switches by sequentially transmitting modulation signals for respective interlocking circuits and detecting the conduction of the modulation signals. CONSTITUTION:A modulation means 1 outputs the modulation signals while a timing signal outputted from a timing instruction means 6 shows a detection period. The modulation signals reach one end of the interlocking circuits 11, 12-n through a first switching means 3. When the limit switch of the interlocking circuit is in an on-state, the modulation signals conduct the interlocking circuit, and they are inputted to an output means 7 through a second switching means 3a, whereby they output an output signal as the detection result of the working state. When the timing signal outputted from the timing instruction means 6 shows a switching period, the first and second switching means 3 and 3a correspond each other and select the interlocking circuit whose working is to be recognized next. Thus, the working state of respective interlocking circuits can individually and easily be detected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an interlock circuit in an injection molding machine safety device (hereinafter referred to as a "safety device") that includes a plurality of interlock circuits each composed of a limit switch. The present invention relates to an operation detection device for detecting an operation state of a motor.

[Prior Art] Conventionally, the operating state of the interlock circuit in this type of safety device has been detected by an alarm device that issues an alarm indicating whether or not the entire safety device is operating normally. It has not been possible with the above alarm device to detect the operating state of each circuit individually. For this reason, when an alarm is issued, the operating status of each interlock circuit is detected using methods A and A below.

B. A method in which a limit switch constituting an interlock circuit is provided on each of the multiple safety doors of an injection molding machine, and the operating state of the limit switch constituting each interlock circuit is detected by visually observing the open/closed state of each safety door. .

B. Each limit switch that makes up each interlock circuit is made up of multiple contacts, and each limit switch's empty contacts (hereinafter referred to as "auxiliary contacts") are used as operation confirmation contacts. A method of connecting to a monitoring device and using this monitoring device to detect the operating status of each limit switch.

[Problems to be Solved by the Invention] Among the conventional methods for detecting the operating state of an interlock circuit described above, method A above requires an inspector to approach and inspect the location where each limit switch is installed. It takes a lot of time and effort. Furthermore, if the limit switch is installed in a location that cannot be accessed by the inspector, there is a problem in that it is not possible to identify which of the plurality of limit switches is operating.

On the other hand, the method described above monitors the operating state of the auxiliary contacts and predicts the operating state of the contacts that actually make up the interlock circuit. Not detected directly. In a limit switch that consists of multiple contacts, even if the auxiliary contact is working, it does not necessarily mean that the contacts used in the interlock circuit are working. Operation confirmation cannot be obtained.

In addition, a limit switch composed of a plurality of contacts may be too large to be installed, so there is a problem that the above method may not be applicable to all interlock circuits.

The present invention has been made in view of the above-mentioned problems of the conventional technology, and detects the operating states of a plurality of limit switches included in an interlock circuit individually and at the mounting location of each limit switch. An object of the present invention is to provide an interlock circuit activation detection device for an injection molding machine safety device that can be directly detected regardless of the situation.

[Means for Solving the Problems] In order to achieve the above object, an interlock circuit operation detection device of an injection molding machine safety device of the present invention is provided for an injection molding machine equipped with a plurality of interlock circuits each constituted by a limit switch. The safety device includes: oscillation means for outputting an alternating current signal; timing instruction means for outputting a timing signal indicating a detection period and a switching period; when the timing signal indicates the detection period, the alternating current signal is passed; a modulation means for outputting a modulation signal; an output means for outputting an output signal when the modulation signal is input; and one position for each end of the interlock circuit in synchronization with the timing signal. a first switching means that sequentially switches to connect the output end of the modulation means; The apparatus is characterized in that it includes a second switching means that connects the input terminal of the output means by sequentially switching the positions one by one.

[Operation] When the AC signal output from the oscillation means is sent to the modulation means, the modulation means outputs the modulation signal while the timing signal output from the timing instruction means indicates the detection period. This modulated signal passes through the first switching means and reaches one end of any one of the interlock circuits. Then, when the limit switch of the interlock circuit is in the on state, the interlock circuit is made conductive,
The signal is inputted to the output means via the second switching means, and an output signal is outputted as the detection result of the operating state.

When the timing signal output from the tying instruction means indicates a switching period, the first and second switching means select the interlock circuit to be checked next in response to each other. In this way, a modulation signal is sequentially sent to each interlock circuit, and conduction of the modulation signal is detected to detect the operating state of each interlock circuit.

[Example] Next, an example of the present invention will be described with reference to the drawings.

As shown in FIG. 1, 11. ! 2.・-2n is composed of two limit switches each operated in response to, for example, opening and closing of a safety door of an injection molding machine (not shown),
A plurality of interlock circuits for controlling 24 V DC for driving the solenoid valve 20, and each interlock circuit 11
,12.・”, n constitutes the main part of the safety device IO.

The first switch 3 connects each interlock circuit 11, 12, .
.... The switch 3a of vJ2 has a switching contact connected to one end (on the left side in the figure) of n, respectively.
It has a switching contact connected to the other end (on the right side in the drawing) of each interlock circuit 11°, 12°, . . . n corresponding to each switching contact of the switching device 3. The switching contacts of the first and second switching devices 3.3a are set one by one in synchronization with the timing signal S2 output from the timing indicator 6 so that the corresponding ones are always selected. It has a switching configuration.

The timing indicator 6 is at a high level during the detection period,
During the switching period, the timing signal S2 (second
(see figure) is output. The oscillator 4 outputs a square wave alternating current signal si (see FIG. 2) having a preset period. When the timing signal 2 is at a high level, the modulator 1 passes the AC signal S1 and outputs it to the first switch 3 as a modulation signal S3 (see FIG. 2). The demodulator 2
The DC component and the noise component are removed from the superimposed signal S5 (see FIG. 2) output from the switch 3a of the switch 3a to extract the AC component, and the demodulated signal S6. (See Figure 2). The receiver 5 inputs the demodulated signal S6 and receives the demodulated signal S6.
A detection signal S7 (see FIG. 2) is output which is high level when the component of the modulated signal S3 is detected, and is low level when the component is not detected. The output device 7 is a buffer that manually outputs the detection signal S7 as a control signal. The output device 7 inputs the timing signal S2, and
The control signal being output is transmitted to each interlock circuit 11, 12 .
-..., n is provided. The demodulator 2, receiver 5, and output device 7 constitute an output means.

Next, the operation of this embodiment will be explained.

First, the AC signal S1 output from the oscillator 4 is transmitted to the modulator l.
sent to. The modulator 1 outputs the AC signal Sl while the timing signal S2 generated by the timing indicator 6 is at a high level.
The modulated signal S3 that has passed is output. The modulated signal S3
passes through the first switch 3 and reaches, for example, one of the interlock circuits 11 (left side in the figure) in the safety device 10.

When at least one of the two limit switches constituting the interlock circuit 11 is in an off (open) state, the modulation signal S3 does not reach the other end (right side in the figure) of the interlock circuit 11. , the demodulated signal S6 input to the receiver 5 via the second switch 3a and the demodulator 2 becomes a flat signal that does not contain the modulated signal S3 as a component.

Therefore, the low level detection signal S7 is output from the receiver 5.
is output, and the low level detection signal S is output from the output device 7.
Similarly to 7, the control signal for the row novel is output. At this time, a display (not shown) of the output device 7 indicates the interlock circuit 11.

On the other hand, when both of the two limit switches constituting the interlock circuit 11 are in the on (closed) state, the modulation signal S3 reaches the other @ (on the right side in the figure) of the first interlock circuit 11, Further, the signal is inputted to the receiver 5 as a demodulated signal S6 via the switch 3a and the demodulator 2.

Since the demodulated signal S6 includes the modulated signal S3 as a component, the receiver 5 that has detected the component of the modulated signal S3 outputs a high-level detection signal S7, and the output device 7 outputs the high-level detection signal S7. Similar to signal S7, a high level control signal is output. As a result, the interlock circuit 11
You can check the operating status of the

Thereafter, the first and second switching devices 3 and 3a are switched in accordance with the timing signal S2 of the timing indicator 6, and the above-described operations are sequentially repeated to complete the remaining interlock circuits.
The operating states of 2 to n can be confirmed along with the display on a display (not shown).

Although the interlock circuits of this embodiment are each composed of two limit switches, the present invention is not limited to this, and may be composed of any number of limit switches greater than or equal to three. Operation status can be inspected.

Furthermore, it goes without saying that the alternating current signal may be a sine wave, a triangular wave, or the like instead of a square wave.

[Effects of the Invention] Since the present invention is configured as described above, it produces the following effects.

Since a signal is sent out sequentially for each interlock circuit and continuity of the signal is detected, the inspector can approach each limit switch no matter where the limit switches that make up each interlock circuit are installed. The operating state of each interlock circuit can be detected individually and easily without any trouble.

Furthermore, since the on/off state of the contacts of each limit switch constituting the interlock circuit is directly detected by signal continuity, reliable and highly reliable inspection can be performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an interlock circuit operation detection device for an injection molding machine safety device of the present invention, and FIG. 2 is a timing chart showing signals of each part of the embodiment of FIG. DESCRIPTION OF SYMBOLS 1... Modulator, 2... Demodulator, 3.3a-switcher, 4- Oscillator, 5... Receiver, 6... Timing indicator, 7... Output device, 10...・Safety equipment, 11.12. ... 20-- Solenoid valve, Sl... AC signal, S2... Timing signal, S3... Modulation signal, SS-- Superimposed signal, S6... Demodulated signal, S7-...・Detection signal. n-...interlock circuit,

Claims (1)

[Claims] 1. In an injection molding machine safety device including a plurality of interlock circuits (11, 12, . . . , n) configured by limit switches: oscillation means for outputting an alternating current signal (S1) (4), timing instruction means (6) for outputting a timing signal (S2) indicating a detection period and a switching period, and a timing instruction means (6) for outputting a timing signal (S2) indicating a detection period and a switching period;
2) indicates the detection period, the AC signal (S1
) and outputs it as a modulated signal (S3), and when the modulated signal (S3) is input,
1 to one end of each of the output means (2, 5, 7) that outputs the output signal and the interlock circuit (11, 12,..., n) in synchronization with the timing signal (S2). The modulation means (1) is sequentially switched one by one.
a first switching means (3) connecting the output ends of the interlock circuits (11, 12, . . . , n) to the other ends of the interlock circuits (11, 12, . . . Corresponding to the first switching means (3), the output means (2, 5, 7) are sequentially switched one by one.
An interlock circuit operation detection device for an injection molding machine safety device, characterized in that it comprises a second switching means (3a) for connecting an input end of the injection molding machine safety device.