KR910007791Y1 - Detection apparatus for power failure of heater in injection molding machine - Google Patents

Abstract

No content.

Description

Heater break detection alarm device of injection molding machine

1 is a schematic circuit diagram in which a magnet connector is driven according to a value set from a temperature sensor by a temperature controller of the present invention.

Figure 2 is a magnet connector and the current transformer connection circuit diagram for each heater load applied to the present invention.

3 is a detailed circuit diagram of the present invention.

4 is a time chart diagram of an output signal relative to an input signal to illustrate the present invention.

5 is a signal waveform diagram induced in the current transformer when the heater is disconnected.

6 is a waveform diagram accumulated in a signal biased at the base of the transistor Q1 and a capacitor on the emitter side.

7 is a time chart of each functional unit according to the drive of the magnet contact according to the present invention.

* Explanation of the protection of the main parts of the drawing

R1-R14: Resistor C1-C6: Capacitor

Q1-Q3: Transistor OP1: Comparator

I1: Inverter Ry: Relay

LED: Light Emitting Diode Vcc: Power Supply Terminal

A10: current sensing circuit section A11: delay output circuit section

A12: LED Monitor A13: NOR Gate

A14: timer A15: or gate

A16: Alarm Output HM: Magnet Contactor

CT1, CT2: Current transformers H1, H2: Heaters

HMa: Magnet contactor Vcc: Supply power terminal

The present invention relates to a heater disconnection detection device of an injection molding machine. In particular, the magnet contactor provides a time delay function during operation, thereby avoiding a transitional operation point, determining an abnormality in a steady state, and detecting a current. By isolating the action between the current transformer and the signal to eliminate mutual influences, and to provide a device that can immediately alarm when a heater failure occurs.

The heater provided in the conventional injection molding machine is simply configured to be adjusted by a temperature controller in a state directly connected to a power source. However, when an error occurs in the heater during use, it cannot immediately sense which part of the heater and the control device is abnormal. In order to do this, they had to check as a tester.

In addition, there is a disadvantage that the main circuit malfunctions due to a surge waveform generated momentarily during operation of the magnet contactor by the temperature controller.

Therefore, it was not possible to immediately deal with the abnormality of the heater, and wasted a lot of time for inspection, and accordingly, there was a lot of discontinuities such as reduced productivity due to unnecessarily delayed operation time of the machinery in which the heater is used.

The present invention detects the abnormality of the heater and detects the abnormality of the heater at an early stage by detecting the current flowing through it when the heater is disconnected in order to solve such a conventional discontinuity. The purpose of this is to provide the internal time delay function for the purpose of preventing surge voltage generated during the operation of the sensor, thereby avoiding the transient operation loss and eliminating the defective product early.

Hereinafter, the configuration of the present invention will be more clearly described with reference to the accompanying drawings.

The overall configuration of the heater disconnection detection circuit includes a current transformer CT for detecting an AC current flowing through the heater, and an ultra short filter circuit and a magnet contact as an interface for comparing the voltage induced in the current transformer CT with a gate circuit. When the time delay circuit (A11) for delaying the time according to the operation, and the LED monitor unit (A12) for sending the monitor and the alarm output by logicalizing the above two signals, it is further broken down and described step by step, As shown in FIG. 1, the non-inverting terminal of the comparator OP1 receives a signal of the current transformer CT that senses a current flowing when the heater is disconnected through a low pass filter composed of a condenser C1 and a resistor R1. The reference terminal resistor R2 for comparing the current transformer CT signal is connected to the inverting terminal thereof, and a feedback resistor R3 is connected between the output side and the output terminal. The base of the transistor Q1 is connected through a low pass filter consisting of a capacitor C2 and a resistor R4. The resistor R5 for limiting the supply power Vcc is connected to the collector, and the capacitor C3 to the emitter. And a resistor (R6) in parallel and then connected to the inverter (I1) and the contact signal of the current sensing comparison circuit (A10) and the magnet contactor (HM) is input to the input through the resistor (R7) of the other (A14) The other input terminal 4 is connected with a low pass filter in which a capacitor C4 and a resistor R8 are connected in parallel, and its power input terminal 6.7.8 is connected to a resistor R9 and a capacitor from a supply power terminal Vcc. NOR gates each having a time delayed output circuit portion A11 and its output terminal 3 and the inverter I1 output terminal of the current sensing comparison circuit portion A10 each connected between (C5) are connected as input power. The output shaft of A13) has a transistor Q2 grounded at the emitter side via resistors R10 and R11. A base is connected to the collector side thereof, a monitor unit A12 having a resistor R12 connected through a light emitting diode (LED) indicating a normal state from a power supply terminal (Vcc), and the inside of the NOR gate A13. On the output side of the OR gate A15 which uses the gate elements U1-U4 as input sources, the resistors R13 and R14 and the alarm output unit A16 composed of the transistor Q3 and the relay Ry are connected to each other. do.

Referring to the operation and effects of the present invention configured as described above are as follows.

The intermittent signal sent by the initial control signal from the temperature controller that uses AC power to drive the magnet contactor (HM) connected to the heater load.

In this state, the selector of the heater disconnection detection (FIG. 1) is selected to determine whether there is a disconnection, and the initial power is supplied to the heater from the normal temperature toward the set temperature without reaching the set temperature. It is assumed that the selector function is valid until the point of time at which it is displayed.

The principle of the selector is that as shown in FIG. 1, the disconnection of the heater is detected by the current transformer CT connected to the heater and detected by the presence / absence of voltage induced on the current transformer CT. Is determined by the principle.

Therefore, when the magnet contactor is driven, the selector unit induces the waveform as shown in FIG. 5 as a contact point of the magnet contactor so that the magnet contactor selects the driver.

At this time, the selected signal is instantaneously delayed by a predetermined delay output circuit unit A11 because the initial input power is alleviated (removed) by the influence of the surge voltage generated while passing through the contact of the magnet contactor.

Therefore, it makes a favorable condition for selection by delaying by the time that the voltage is generated and then making the next signal the normal signal.

The time chart relationship of the delay output circuit A11 with respect to the selection signal is shown in Fig. 4 as shown in FIG. Terminal), and the input signal has the output value changed by the RC time constant value of the capacitor C4 and the resistor R8 through the terminal (3) of the timer A14. (A13) It is output through the input terminal.

That is, the input / output relation of the output delay signal is delayed when operating the RC time constant value and the timer power supply used as DC 5V as shown in Fig. 4, but it takes about 0.5 seconds. In the state where the output signal converted to is waited to be applied to the NOR gate A13, the current transformer detection signal from the current transformer CT shown in FIG. 2 passes through the differential circuit composed of the capacitor C1 and the resistor R3. The non-inverting terminal (+) of the comparator OP1 is applied.

At this time, it is compared with the value of the intrinsic resistance (R) connected to the inverting (-) terminal to determine its output potential.

Here, the principle of dedicating the signal generated by the current transformer CT1 will be supplemented. In addition, the heater H1 load line penetrates once in the connection of the current transformer CT1 input to the base of the transistor Q1. Passed through, the waveform signal induced in the current transformer (CT1) of the reduced current type and the annular core of the general current transformer is input through the capacitor (C2), only the positive portion of the waveform of the base input signal of the transistor (Q1) It is used as.

Therefore, the value of the positive electrode signal selected as the base signal is smoothed by the capacitor C3 connected to the emitter of the transistor Q1, and the accumulated waveform of the DC component is output with the signal biased as shown in FIG. This is normalized by the buffer circuit of the inverter I1.

Through this process, the emitter side signal of the transistor Q1 is normalized by the inverter I1, and the output signal through this becomes high, and its output remains high for 0.5 seconds even when the actual signal of the current transformer CT1 input stage is not instantaneously applied. Will keep.

This outputs until the capacitor C3 connected to the emitter is fully charged and gradually discharges to low potential, which is the same as when it is driven even when the magnet condenser HM is turned off. Since a surge voltage is generated, it is necessary as a delay circuit to escape from the influence.

The waveform time of each functional unit according to the driving of the magnet condenser HM is as shown in FIG. 7, but the heater used for the nozzle (H1) usually has a current capacity equal to or less than 1 ampere (A) of the current transformer (CT1). ), The peak voltage induced by the waveguide becomes low, so that its signal needs to be first amplified.

In this state, the selected normal signal output through the timer A14 output terminal 3 of the delay output circuit unit A11 and the detected normal signal output through the inverter I1 of the current sensing circuit unit A10 are It is transmitted to the input terminal of the NOR gate LED (A13) for the LED (Light Emitting Diode) monitor signal. However, the condition for the operation of the transistor (Q2) and the light emitting diode (LED) is high. Should be

Here, the input condition for the NOR gate A13 to be output high is when two input signals sensed by the selector and the detector are in a low state. As described above, the detector signal and the selector signal overlap each other by a delay time. Thus, the surge waveform generated when the magnet contactor HM is operated does not cause the output of the NOR gate A13 to become high in a normal state.

As described above, in order to determine the heater disconnection detection state for one heater H1, the number of heaters used in the injection molding machine is up to 12 heaters depending on the model, so that the corresponding current transformers CT and The same circuit as shown in FIG. 3 is prepared separately, and the disconnection detection signal according to the disconnection of each heater is input to the ore gate A15 input terminal of the alarm output unit A16, and each of the NOR gates A13 of the LED monitor unit A12. As the outputs U1-U4 are applied, each output of the NOR gate A13 is driven by the OR gate A15 to drive the transistor Q3 to drive the relay Ry.

Accordingly, when the heaters are set to break, the LEDs of the LED monitor A12 are turned on to alarm the alarms of the alarm unit A16.

As described above, the present invention not only can alleviate and eliminate the surge voltage generated while the heater, which is a problem of the conventional heater disconnection detection circuit, is controlled by the magnet contactor, but also momentarily operates the light emitting diode for the monitor. If an error occurs or the capacity of the heater is large, the wiring cannot be wound on the current transformer, and the induced voltage at the time of passing through it is uncertainly detected. The circuit measures against the surge generation at the time of driving and the time of short circuit are sufficiently prepared, thereby reducing the down time of the injection molding machine in which the heater is installed, thereby improving the productivity.

Claims (1)

The non-inverting (+) terminal of the comparator (OP1) is connected so that the signal of the current transformer (CT) that senses the current flowing when the heater is disconnected is applied through a low pass filter composed of a capacitor (C1) and a resistor (R1). The terminal is connected to the reference set value resistor (R2) for comparing the current transformer (CT) signal, the feedback resistor (R3) is connected between the output side, and also the low range consisting of a capacitor (C2) and a resistor (R4) The base of the transistor (q1) is connected through a filter, the resistor (R5) for supply power (Vcc) limiting is connected to the collector side, the capacitor (C3) and the resistor (R6) in parallel to the emitter and then the inverter ( The capacitor C4 and the resistor are connected to the other input terminal 4 of the timer A14, in which the contact signal between the current sensing comparison circuit A10 and the magnet contactor HM, which is connected to I1), is input through the resistor R7. (R8) connects the low pass filter connected in parallel, and its power input terminal (6.7.8) Inverter of time-domain output circuit section A11 and its output terminal 3 and current sensing comparison circuit section A10 formed by connecting between a resistor R9 and a capacitor C5 from a power supply terminal Vcc, respectively. (I1) The base of the transistor Q2 having the emitter side grounded through the resistors R10 and R11 is connected to the output side of the NOR gate A13 having the output terminal as an input source, respectively, and to the collector side thereof a supply power terminal ( A monitor unit A12 in which a resistor R12 is connected through a light emitting diode LED indicating a normal state from Vcc, and an internal source element U1-U4 of the NOR gates A13 as an input source. The heater disconnection detection and warning device of an up-and-molding molding machine, characterized in that the output of the gate (A15) is configured by interconnecting an alarm output unit (A16) consisting of a resistor (R13) (R14), a transistor (Q3) and a relay (Ry).