A cavity heating temperature control circuit for a tunnel furnace

Abstract

The utility model relates to a cavity heating temperature control circuit of tunnel furnace, including main circuit and control circuit, and main circuit includes circuit breaker, fuse, contactor, heating pipe group and fan, and control circuit includes frequency changer and detection module, and detection module includes first temperature sensor and a plurality of second temperature sensors, and control circuit still includes PLC controller and relay, and the output of first temperature sensor and second temperature sensor all are connected with the input of PLC controller, and the output of PLC controller connects the coil of relay, and the normally open contact of relay connects frequency changer, and fan forms loop through frequency changer and connects power supply, and the coil of circuit breaker is also connected to the output of PLC controller, and heating pipe group forms loop through circuit breaker and connects power supply, the utility model discloses setting first temperature sensor at the import of tunnel furnace, sets up a plurality of second temperature sensors on the furnace body, and the control of fan and heating pipe group is realized in combination with PLC controller.

Description

Technical Field

[0001] This utility model relates to the field of tunnel furnace temperature control technology, specifically to a cavity heating temperature control circuit for a tunnel furnace. Background Technology

[0002] The existing tunnel furnace employs a dual-chamber structure, with each chamber operating independently. Each chamber's inlet is equipped with a dedicated fan and heating element, utilizing airflow for heat transfer. To control the temperature of each chamber separately, two completely independent control systems are configured. However, the current system suffers from several problems in practical application: First, system assembly is time-consuming and labor-intensive, resulting in low assembly efficiency and extremely cumbersome subsequent maintenance and daily control operations, causing significant inconvenience to staff. Second, the microcontrollers used in the current control system are susceptible to interference from environmental factors (such as electromagnetic interference and temperature changes), leading to poor operational stability and an inability to maintain precise control. Furthermore, from a system integration perspective, these microcontrollers are difficult to integrate with other equipment or systems, severely limiting the scalability and intelligence of the entire tunnel furnace control system.

[0003] Now that the upper and lower cavities of the tunnel furnace are connected, a simple integrated control circuit is urgently needed to control the heating temperature of the tunnel furnace. Summary of the Invention

[0004] To address the problem that existing circuit structures are complex and cannot be integrated with tunnel furnace structures, this invention proposes a cavity heating temperature control circuit for a tunnel furnace. A first temperature sensor is installed at the inlet of the tunnel furnace, and multiple second temperature sensors are installed on the furnace body. Combined with a PLC controller, the circuit controls the fan and heating tube assembly, thus providing a hardware foundation for heating temperature control.

[0005] To achieve the above objectives, this utility model proposes a cavity heating temperature control circuit for a tunnel furnace, comprising a main circuit and a control circuit. The main circuit includes a circuit breaker, a fuse, a contactor, a heating tube assembly, and a fan. The control circuit includes a frequency converter and a detection module. The detection module includes a first temperature sensor and multiple second temperature sensors. The control circuit also includes a PLC controller and a relay. The output terminals of the first and second temperature sensors are both connected to the input terminal of the PLC controller. The output terminal of the PLC controller is connected to the coil of the relay. The normally open contact of the relay is connected to the frequency converter. The fan is connected to a power supply through the frequency converter to form a circuit. The output of the PLC controller is also connected to the coil of the circuit breaker, and the heating tube group is connected to the power supply through the circuit breaker to form a circuit.

[0006] Furthermore, the temperature sensor includes a thermocouple.

[0007] Furthermore, the first temperature sensor is located at the inlet of the tunnel furnace, and multiple second temperature sensors are distributed in a square at equal intervals along the tunnel furnace, with one second temperature sensor located in the middle of the tunnel furnace.

[0008] The detection module of this circuit includes a first temperature sensor and multiple second temperature sensors. The temperature sensors are thermocouples, which are characterized by high measurement accuracy and fast response speed, enabling precise capture of temperature changes. Simultaneously, the first temperature sensor is located at the inlet of the tunnel furnace, allowing real-time monitoring of the initial temperature entering the cavity. Multiple second temperature sensors are distributed in a square, equidistant pattern along the tunnel furnace, with one sensor in the center, providing comprehensive coverage of the furnace cavity. This accurately monitors the temperature in different areas, avoiding blind spots in localized temperature monitoring and providing reliable data for subsequent precise temperature control.

[0009] Furthermore, one end of the circuit breaker is connected to a power source, and the other end is connected to a frequency converter. The frequency converter is connected to the fan, forming a fan temperature control circuit. The frequency converter is connected to an RS485 module, and the frequency converter communicates with the PLC controller through the RS485 module.

[0010] In terms of fan control, the circuit breaker, frequency converter, and fan mechanism form the fan temperature control circuit. The circuit breaker provides overload and short-circuit protection for the circuit, preventing damage to the fan due to circuit faults. Furthermore, the frequency converter connects to an RS485 module to communicate with the PLC controller. The PLC can send control commands to the frequency converter in real time via the RS485 module to adjust the fan speed.

[0011] Furthermore, one end of the circuit breaker is connected to a power source, and the other end is connected to a fuse. The other end of the fuse is connected to the normally open contact of the circuit breaker, and the other end of the normally open contact of the circuit breaker is connected to the heating tube assembly to form a heating tube assembly start-stop circuit.

[0012] Furthermore, a solid-state relay is also provided between the normally open contact of the circuit breaker and the heating tube assembly. The coil of the solid-state relay is connected to the output terminal of the PLC controller, and one end of the normally open contact of the solid-state relay is connected to the normally open contact of the circuit breaker, while the other end is connected to the heating tube assembly.

[0013] In the start-stop circuit of the heating element assembly, a circuit breaker, a fuse, and the normally open contact of the circuit breaker are connected in sequence. The circuit breaker and fuse provide dual protection, effectively handling circuit overload and short circuit situations and protecting the heating element assembly from damage. Simultaneously, a solid-state relay is installed between the normally open contact of the circuit breaker and the heating element assembly. Its coil is connected to the output terminal of the PLC controller. The PLC can further precisely control the operating status of the heating element assembly by controlling the on / off state of the solid-state relay.

[0014] Furthermore, both the fan and the heating tube assembly are located at the entrance of the tunnel furnace.

[0015] The beneficial effects of this utility model through the above technical solution are as follows: (1) This utility model integrates a PLC controller, a first temperature sensor and multiple second temperature sensors, a frequency converter, a solid-state relay and other components through the coordination of the main circuit and the control circuit. The first temperature sensor captures the initial temperature at the inlet of the tunnel furnace in real time, providing an initial data reference for temperature control. Multiple second temperature sensors are distributed equidistantly along the square of the tunnel furnace, with one additional sensor in the middle, fully covering the cavity and accurately feeding back the temperature of different areas. The PLC controller receives the temperature data and, on the one hand, precisely adjusts the start and stop status of the heating tube group by controlling the on and off of the solid-state relay. On the other hand, it communicates with the frequency converter through the RS485 module to adjust the fan speed in real time, thereby achieving temperature control.

[0016] (2) The circuit breaker and fuse in the main circuit of this utility model form a double protection. When the circuit has overload, short circuit or other faults, the circuit breaker can quickly cut off the power supply, and the fuse, as a secondary protection, further blocks the fault current to avoid the fault from expanding and damaging core components such as heating tube group and fan. This multi-level protection design reduces the equipment failure rate, reduces maintenance costs and downtime, and improves overall production efficiency. Attached Figure Description

[0017] Figure 1 This is one of the circuit diagrams for a cavity heating temperature control circuit of a tunnel furnace according to this utility model; Figure 2 This is the second circuit diagram of a cavity heating temperature control circuit for a tunnel furnace according to the present invention. Figure 3 This is the third circuit diagram of the cavity heating temperature control circuit of the tunnel furnace according to the present invention.

[0018] The reference numerals are as follows: 1 is circuit breaker, 2 is fuse, 3 is contactor, 4 is heating tube assembly, 5 is fan, 6 is frequency converter, 7 is first temperature sensor, 8 is PLC controller, 9 is relay, 10 is solid-state relay, and 11 is second temperature sensor. Detailed Implementation

[0019] Example 1 like Figure 1-3As shown, a cavity heating temperature control circuit for a tunnel furnace includes a main circuit and a control circuit. The main circuit includes a circuit breaker 1, a fuse 2, a contactor 3, a heating tube assembly 4, and a fan 5. The control circuit includes a frequency converter 6 and a detection module. The detection module includes a first temperature sensor 7 and multiple second temperature sensors 11. The control circuit also includes a PLC controller 8 and a relay 9. The output terminals of the first temperature sensor 7 and the second temperature sensors 11 are both connected to the input terminal of the PLC controller 8. The output terminal of the PLC controller 8 is connected to the coil of the relay 9. The normally open contact of the relay 9 is connected to the frequency converter 6. The fan 5 is connected to a power supply through the frequency converter 6 to form a circuit. The output terminal of the PLC controller 8 is also connected to the coil of the circuit breaker 1, and the heating tube group 4 is connected to the power supply through the circuit breaker 1 to form a circuit.

[0020] The temperature sensor 7 includes a thermocouple.

[0021] The first temperature sensor 7 is located at the inlet of the tunnel furnace, and a plurality of second temperature sensors 11 are distributed in a square at equal intervals along the tunnel furnace, with one second temperature sensor 11 located in the middle of the tunnel furnace.

[0022] One end of the circuit breaker 1 is connected to the power supply, and the other end is connected to the frequency converter 6. The frequency converter 6 is connected to the fan 5, forming a fan temperature control circuit. The frequency converter 6 is connected to an RS485 module, and the frequency converter 6 communicates with the PLC controller 8 through the RS485 module.

[0023] One end of the circuit breaker 1 is connected to the power supply, and the other end is connected to the fuse 2. The other end of the fuse 2 is connected to the normally open contact of the circuit breaker 1. The other end of the normally open contact of the circuit breaker 1 is connected to the heating tube group 4 to form the heating tube group start-stop circuit.

[0024] A solid-state relay 10 is also provided between the normally open contact of the circuit breaker 1 and the heating tube group 4. The coil of the solid-state relay 10 is connected to the output terminal of the PLC controller 8. One end of the normally open contact of the solid-state relay 10 is connected to the normally open contact of the circuit breaker 1, and the other end is connected to the heating tube group 4.

[0025] The fan 5 and the heating tube assembly 4 are both located at the entrance of the tunnel furnace.

[0026] In this embodiment, there are five second temperature sensors 11, four of which are located at both ends of the tunnel furnace and one in the middle of the tunnel furnace.

[0027] During operation, the PLC controller 8 receives the initial inlet temperature data transmitted by the first temperature sensor 7. If the initial temperature is lower than the target temperature, the PLC controller 8 outputs a signal to the coil of the circuit breaker 1, causing the normally open contact of the circuit breaker 1 to close. Simultaneously, it controls the coil of the solid-state relay 10 to be energized, closing its normally open contact. The heating tube group 4 is then powered on through the heating tube group start-stop circuit, and heating begins. During the heating process, multiple second temperature sensors 11 collect temperature data from different areas of the tunnel furnace cavity in real time and transmit it to the PLC controller 8. If the PLC controller 8 detects that the temperature is higher at the beginning and lower at the end, it sends an acceleration command to the frequency converter 6 via the RS485 module. The frequency converter 6 adjusts the speed of the fan 5 to increase, causing the hot air to flow to the rear. If the temperatures are similar, the frequency converter 6 adjusts the fan 5 to operate at a uniform speed. At the same time, if the temperature is too high, the PLC controller 8 reduces the energizing frequency of the solid-state relay 10, gradually reducing the operating power of the heating tube group 4 to avoid temperature overshoot. During operation, if the main circuit is overloaded (such as a short circuit in heating tube group 4), circuit breaker 1 will quickly cut off the power supply, and fuse 2 will act as secondary protection to prevent the fault current from expanding. If PLC controller 8 detects abnormal temperature sensor data (such as no signal transmission), inverter 6 malfunction (such as overcurrent alarm), or solid-state relay 10 fails to act as instructed, it will immediately output a protection signal, cut off the power supply to heating tube group 4, and reduce the speed of fan 5 to the minimum safe speed to ensure system safety.

[0028] The embodiments described above are merely preferred embodiments of this utility model and are not intended to limit the scope of implementation of this utility model. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the patent claims of this utility model should be included within the scope of the patent application of this utility model.

Claims

1. A cavity heating temperature control circuit for a tunnel furnace, comprising a main circuit and a control circuit, wherein the main circuit includes a circuit breaker (1), a fuse (2), a contactor (3), a heating tube assembly (4), and a fan (5), and the control circuit includes a frequency converter (6) and a detection module, characterized in that, The detection module includes a first temperature sensor (7) and multiple second temperature sensors (11). The control circuit also includes a PLC controller (8) and a relay (9). The output terminals of the first temperature sensor (7) and the second temperature sensor (11) are both connected to the input terminal of the PLC controller (8). The output terminal of the PLC controller (8) is connected to the coil of the relay (9). The normally open contact of the relay (9) is connected to the frequency converter (6). The fan (5) is connected to the power supply through the frequency converter (6) to form a circuit. The output terminal of the PLC controller (8) is also connected to the coil of the circuit breaker (1), and the heating tube group (4) is connected to the power supply through the circuit breaker (1) to form a circuit.

2. The cavity heating temperature control circuit of a tunnel furnace according to claim 1, characterized in that, The temperature sensor (7) includes a thermocouple.

3. The cavity heating temperature control circuit of a tunnel furnace according to claim 1, characterized in that, The first temperature sensor (7) is located at the inlet of the tunnel furnace, and multiple second temperature sensors (11) are distributed in a square at equal intervals along the tunnel furnace, with one second temperature sensor (11) located in the middle of the tunnel furnace.

4. The cavity heating temperature control circuit of a tunnel furnace according to claim 1, characterized in that, One end of the circuit breaker (1) is connected to the power supply, and the other end is connected to the frequency converter (6). The frequency converter (6) is connected to the fan (5) to form a fan temperature control circuit. The inverter (6) is connected to an RS485 module, and the inverter (6) communicates with the PLC controller (8) through the RS485 module.

5. The cavity heating temperature control circuit of a tunnel furnace according to claim 1, characterized in that, One end of the circuit breaker (1) is connected to the power supply, and the other end is connected to the fuse (2). The other end of the fuse (2) is connected to the normally open contact of the circuit breaker (1). The other end of the normally open contact of the circuit breaker (1) is connected to the heating tube group (4) to form the heating tube group start-stop circuit.

6. The cavity heating temperature control circuit of a tunnel furnace according to claim 1, characterized in that, A solid-state relay (10) is also provided between the normally open contact of the circuit breaker (1) and the heating tube group (4). The coil of the solid-state relay (10) is connected to the output terminal of the PLC controller (8). One end of the normally open contact of the solid-state relay (10) is connected to the normally open contact of the circuit breaker (1), and the other end is connected to the heating tube group (4).

7. The cavity heating temperature control circuit of a tunnel furnace according to claim 1, characterized in that, The fan (5) and the heating tube assembly (4) are both located at the entrance of the tunnel furnace.

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