KR0130908B1 - Heater controller of a furnace - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater control apparatus for a heat treatment furnace, and in particular, a manual input unit (1), a manual input processing unit (2), a reference value input unit (3), a detection signal processing unit (4), an interface unit (5), and a key input unit (6). , Key input signal processor 7, monitor 8, external display driver 9, input current detector 10, power supply 11, SCR driver 12, output voltage detector 13, silicon control By connecting the microcomputer 20 having the rectifier element (SCR), the fan (FAN), and the phase control / zero crossing control selector 21 to form an integrated heater control system, it can be used externally and in common. It can control proportionally several heaters connected in parallel, and can monitor the change of load from time to time to predict the abnormality and maintenance time of equipment, and also minimize downtime due to equipment failure, especially remote Maintain centralized monitoring system It can greatly reduce the Riviera.

Description

Heater Control Device of Heat Treatment Furnace

1 is a block diagram of a heater control device of the present invention.

* Explanation of symbols for the main parts of the drawings

1: Manual input unit 2: Manual input processing unit

3: reference value input unit 4: detection signal processing unit

5: interface unit 6: key input unit

7: key input signal processing unit 8: monitor unit

9: External display driver 10: Input current detector

11: power supply unit 12: SCR drive unit

13: output voltage detector 20: microcomputer

21: phase control / zero crossing control selector

SCR: Silicon Controlled Rectifier

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater control device invented to precisely control the amount of heat generated by a heater installed in an industrial furnace. In particular, a microcomputer is required to accurately perform phase control of a silicon control rectifying element (SCR) for heater control in a microcomputer. The present invention relates to a heater control apparatus of a heat treatment furnace capable of supplying power to a load to prevent unnecessary waste of power and of producing a high-precision product. Heaters such as furnaces that are conventionally used as a means for generating high temperature heat can be precisely controlled by controlling the power supplied thereto by a switch that is simply turned on / off. Unnecessary power was wasted, and there was no function to detect disconnection of the heater.

By the way, even though several or dozens of heaters are installed in parallel in most heat treatment furnaces, one or two heater disconnection states are not known, and only about half or more of them are disconnected. As a result of the inspection of the device, there is a problem that the production of a predetermined product during the downtime of the device has a lot of disruption as well as the convenience and precision of the operation are deteriorated. An object of the present invention is to form a heater control system integrally and can be used in common with the external type, and to control proportion of several sets by parallel control as well as to monitor the changes in the load from time to time whether there is an abnormality of the device In addition, the present invention provides a heater control device for a heat treatment furnace that can predict maintenance time and minimize downtime due to equipment failure.

Another object of the present invention is to provide a heater control apparatus for a heat treatment furnace that can install the interface to the heater control device to be able to centrally manage the system in the central monitoring panel in which the computer is installed, thereby reducing the maintenance cost.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of the device of the present invention. In controlling the heat generation amount of the heater H installed in the heat treatment furnace, the user sets various data (for example, reference set values according to temperature, current, and voltage). Manual input unit (1) for directly inputting; A manual input processing unit (2) which receives the analog signal output from the manual input unit (1) and converts it into a digital signal and outputs it to the microcomputer (20); A reference value input unit 3 which receives current, voltage, and temperature values and 4-20 mA DC current signals as reference for controlling the device and amplifies them to a predetermined level and outputs them to the microcomputer 20; A detection signal processor 4 for amplifying a detection signal output from a temperature detection sensor installed in a heat treatment furnace to a predetermined level and compensating for linearity; An interface unit 5 for allowing the computer and the microcomputer 20 of the central monitoring panel to communicate with each other; A key input unit (6) provided with a heater drive control switch (S1), an automatic / manual mode selection switch (S2), and an external input selection switch (S3, S4) and selectively operated by a user; A key input signal processing unit 7 for converting a contact signal output from the key input unit 6 into a TTL (Transistor Transistor Logic) signal and inputting it to a microcomputer; Mode selection key 81, up / down keys 82 and 83, setting key 84, automatic check key 85, and liquid crystal panel 86 and bar graph for displaying various data operated by a user. A monitor section 8 having 87, for inputting and displaying various parameters; A relay RY1 operated by an output signal of the microcomputer 20 generated when an abnormality occurs in the device to drive the abnormality display unit 14; A relay RY2 operated by an output signal of the microcomputer 20 generated when the device is normally driven to output a normal signal; An external display driver 9 for outputting a current of 4-20 mA to an external display under this control; An input current detection unit 10 for converting an alternating current detected by two current transformers CT installed at two power supply lines into a DC voltage; A power supply unit 11 for operating the respective units in synchronization with the AC voltage and applying a power voltage to the respective units; An SCR driver 12 for controlling a phase and a zero crossing point in accordance with a synchronization signal output from the microcomputer 20 to apply a predetermined voltage to the gate of the silicon controlled rectifying element SCR; An output voltage detector 13 for converting an AC voltage output from the silicon controlled rectifier element SCR into a DC voltage; A heat sink for dissipating heat to the silicon controlled rectifier device SCR for supplying an AC voltage corresponding to the output signal of the SCR driver 12 to the heater H and the silicon controlled rectifier device SCR. Fan (FAN) for cooling the; It is characterized in that it comprises a microcomputer 20 for receiving a predetermined input signal from each unit to perform a predetermined program to perform the overall control function of the system.

At this time, the microcomputer 20 includes a phase control / zero crossing control selector 21 for determining whether to control the silicon controlled rectifier element SCR by phase control or zero crossing detection.

In addition, the microcomputer 20 also detects the rate of change of the load by the output voltages of the input current detector 10 and the output voltage detector 13 to determine whether there is a disconnection.

Where reference numeral ACL is an alternating voltage (AC) director and FU is a fuse.

When the effects of the present invention configured as described above are variously named.

First, while the user selects the automatic / manual mode selection switch S2 installed in the key input unit 6 as the manual mode, the reference value according to temperature, current, and voltage for controlling a predetermined device is directly controlled through the manual input unit 1. When input, the analog input signal output from the manual input unit 1 in the manual input processing unit 2 connected thereto converts the analog signal into a digital signal and inputs it to the microcomputer 20.

That is, the microcomputer 20 drives the device based on the reference values input through the manual input unit 1 when the automatic / manual mode selection switch S2 installed in the key input unit 6 is selected as the manual mode. Control.

In addition, the reference value input unit 3 amplifies a DC current signal having a reference current, a voltage, and a temperature of 4-20 mA to a predetermined level and inputs it to the microcomputer 20 to automatically control the device. When the automatic / manual mode selection switch S2 installed in the input unit 6 is selected as the automatic mode, the device is automatically controlled by these reference values.

The detection signal processor 4 amplifies the minute detection signal output from the temperature detection sensor installed in the heat treatment furnace to a predetermined level and compensates its linearity so that the temperature control of the system can be accurately performed.

Meanwhile, since the interface unit 5 of RS-485 is installed between the microcomputer 20 of the present invention, the microcomputer 20 of the present invention can concentrate all the management of the system even at a remote location, thereby reducing the maintenance cost of the system. It can save a lot.

In addition, the key input unit 6 is provided with a variety of keys that the user can operate for the overall control of the device, if specifically described that whether to heat the power supply to several heaters (H) installed in the heat treatment furnace, etc. Heater drive control switch (S1) for selecting the, and the manual mode of the control of the device by the data input from the manual input unit 1 or the automatic mode achieved by the reference value input from the reference value input unit (3) An automatic / manual mode selection switch S2 for determining which mode to select and two external input selection switches S3 and S4 for selecting data input from the outside when the manual mode is selected are provided.

At this time, since the contact signal according to the operation of each switch is output from the key input unit 6, the key input signal processing unit 7 provided between the key input unit 6 and the microcomputer 20 converts the contact signal into the microcomputer 20. Is converted into a TTL signal for recognition.

In addition, at the output terminal of the microcomputer 20, various parameters can be input, and a monitor unit 8 for displaying the operation status of the device including various data is also provided. Mode selection key 81 for selecting each function, up / down keys 82 and 83 for data up or down, and setting keys for determining predetermined data when inputting various data for control, etc. (84) and an automatic check key (85) for detecting abnormality status of the equipment, and at the same time, a liquid crystal display panel (86) for displaying various data in letters and numbers, and predetermined temperatures in bar graph form. A bar graph 87 is provided for presentation.

Therefore, the user can easily know the input / output value and abnormal state of various data by only looking at this monitor installed in the field, and can easily change various data necessary for controlling the device.

On the other hand, two current transformers CT for detecting power supply and overload are installed in two power supply lines among the three phase power supply lines, and the detection current of the current transformer CT is determined by the input current detector 10. Is converted into a predetermined DC voltage and input to the microcomputer 20.

Accordingly, the microcomputer 20 receives the voltage (current) output from the input current detector 10 and compares the time with the instantaneous or instantaneous set value to detect whether the overcurrent (OCR) and the instantaneous overcurrent (IOC) state is present. If it turns out to be an overcurrent or instantaneous overcurrent state, the relay RY1 is driven to generate an alarm sound.

In addition, the power supply unit 11 converts the AC voltage supplied from the three-phase power line to a predetermined DC voltage and applies it to each part, and simultaneously detects a synchronous signal from the AC voltage and inputs it to the microcomputer 20. Each part operates in synchronization with this AC power supply.

In addition, the output voltage detector 13 connected between the output terminal of the silicon control rectifying element SCR and the microcomputer 20 converts the AC voltage output due to the driving of the silicon control rectifying element SCR into a direct current voltage. 20). At this time, the microcomputer 20 can recognize the abnormality of the silicon control rectifier SCR and the heater H by the output signal of the output voltage detector 13.

In addition, the microcomputer 20 detects the variation rate of the load by a method of comparing the output voltage of the output voltage detector 13 and the output voltage of the input current detector 10 to determine whether there is a disconnection. If it is determined that a predetermined part is disconnected, the alarm is generated by driving the relay RY1 as described above, so that the user can easily recognize the state of the load through the alarm sound.

On the other hand, since the microcomputer 20 outputs a predetermined control signal to the SCR driver 12 in accordance with the detected synchronization signal, the SCR driver 12 outputs a predetermined angle to the gate of the silicon control rectifier SCR. The low-phase controlled driving voltage or the zero crossing point controlled driving voltage are output.

That is, the microcomputer 20 includes the phase control / zero crossing control selector 21 for determining whether to control the silicon controlled rectifier element SCR by phase control or zero crossing detection. In the SCR driver 12 receiving the control signal from the control panel, the driving voltage or the zero crossing point (these are selected by the program in the microcomputer) which is phase-controlled at a predetermined angle can output the controlled driving voltage.

Therefore, since the silicon control rectifier SCR passes only an AC voltage corresponding to the gate driving voltage output from the SCR driver 12 and applies it to the heater H, the heater H corresponds to the power supplied. It is to generate a calorific value.

At this time, since the silicon control rectifier (SCR) is passed through a relatively high voltage there is a possibility that a lot of heat is generated and may be damaged, so a heat sink is installed to prevent this, if the natural heat convection to the heat sink is reduced heat dissipation efficiency By installing a separate cooling fan (FAN) it is possible to prevent the silicon control rectifier (SCR) from being burned out by heat in advance.

In addition, the relay RY2 installed at the output terminal of the microcomputer 20 is driven under the control of the microcomputer 20 when the device is normally driven to drive a lamp for indicating a normal state, and the external display driver 9 Under the control of the microcomputer 20 outputs a current of 4-20mA to serve as an external display.

On the other hand, the microcomputer 2, which receives predetermined input signals from each unit and performs a predetermined program stored therein, performs the overall control function of the system. It also has a constant voltage control function that performs the setting function of the slope to gradually change and compares the reference voltage of the reference value input unit 3 and the detected voltage of the output voltage detector 13 to output a constant voltage.

In addition, it has a constant current control function for outputting a constant current by comparing the reference current of the reference value input section 3 and the detection current of the input current detection section 10 with each other, and programming of 12 patterns by a pre-programmed temperature pattern. It has an output function, and performs a feedback function of the temperature signal for processing the external temperature linearly, and compares the output of the reference value input unit 3 and the output signal of the detection signal processing unit 4 with the result as a result of the heater (H). It also performs temperature control function to maintain constant temperature by controlling.

As described above, according to the present invention, by integrally forming a heater control system, it can be used in common with an external type, and can proportionally control several heaters connected in parallel, and frequently monitor the change in load to generate an abnormality of the device. It can anticipate the presence and maintenance time, minimize downtime due to equipment breakdown, and can centrally manage the system in the central monitoring panel at the remote site, greatly reducing maintenance costs. You can expect it.

Claims (4)

In controlling the amount of heat generated by the heater (H) installed in the heat treatment furnace, the manual input unit (1) for the user to directly input a variety of data; A manual input processor (2) for receiving an analog signal output from the manual input unit (1) and converting the analog signal into a digital signal; A reference value input section (3) for receiving a reference current, voltage and temperature values for controlling the device, and amplifying to a predetermined level with a DC current signal of 4-20 mA; A detection signal processing unit 4 for compensating for linearity of the detection signal output from a temperature detection sensor installed in a heat treatment furnace or the like; A key input unit (6) having a heater driving control switch (S1), an automatic / manual mode selection switch (S2), and external input selection switches (S3, S4) and selectively operated by a user; A key input signal processor (7) for converting the contact signal output from the key input unit (6) into a TTL signal; A monitor unit 8 for inputting and displaying various parameters; A relay RY1 for driving the abnormal part display unit 14 when an abnormality occurs in the device and a predetermined signal is output from the microcomputer 20; A relay RY2 for driving a steady state display unit when the device is normally driven; An external display driver 9 for outputting a current of 4-20 mA to an external display under the control of the microcomputer 20; An input current detector 10 for converting an AC current detected through two current transformers CT into a DC voltage; A power supply unit 11 for operating the respective units in synchronization with the AC voltage and applying a power voltage to the respective units; An SCR driver 12 for changing the gate voltage of the silicon controlled rectifying element SCR according to a synchronization signal output from the microcomputer 20; An output voltage detector 13 for converting an AC voltage output through the silicon controlled rectifier element SCR into a DC voltage; A silicon controlled rectifier (SCR) for supplying electric power corresponding to the output signal of the SCR driver 12 to the heater H; A fan (FAN) attached to the silicon control rectifier (SCR) to cool the heat sink to emit heat to the outside; Heater control apparatus for a heat treatment furnace, characterized in that it comprises a microcomputer (20) for receiving a predetermined input signal from each unit to perform a predetermined program to perform the overall control function of the system. The microcomputer 20 of claim 1, wherein the microcomputer 20 includes a phase control / zero crossing control selector 21 for determining whether to control the silicon controlled rectifier element SCR by phase control or zero crossing detection. Heater control device of the heat treatment furnace characterized in that. The heater control apparatus according to claim 1, wherein an interface unit (5) is provided between the microcomputer (20) and the central monitor computer at a remote location to enable mutual communication. 2. The monitor unit (8) according to claim 1, wherein the monitor unit (8) includes a mode selection key (81), an up / down key (82, 83), a setting key (84), and an automatic check key (85) which are selectively operated by a user. And a liquid crystal panel (86) and a bar-graph (87) for displaying various data.