A heat treatment resistance furnace with double PID temperature control system

Abstract

The utility model discloses a kind of heat treatment resistance furnace of double PID temperature control system, related to heat treatment resistance furnace technical field, comprising: all-fiber furnace body, heating resistance wire, temperature control thermocouple, temperature control module, over-temperature thermocouple, over-temperature module, early-warning thermocouple, early-warning module, control box, the utility model passes through double PID temperature control system heat treatment resistance furnace, early-warning thermocouple and early-warning temperature control module are additionally provided, increase a set of PID temperature control system mainly for making equipment temperature keep smooth to avoid fluctuation, avoid temperature fluctuation too big, over-temperature thermocouple ensures when temperature over-temperature, timely power-off avoids product scrapping. Such design improves equipment temperature control performance, improves the first and qualified rate of product, ensures that equipment normal operation, more energy saving, reduce the production energy cost, increase the competitiveness of company in industry, improve social benefit.

Description

Technical Field

[0001] This utility model relates to the field of heat treatment resistance furnace technology, specifically a heat treatment resistance furnace with a dual PID temperature control system. Background Technology

[0002] With the continuous development of new energy sources, offshore wind power has also ushered in a new era of development opportunities. As a supplier of wind turbine flanges, improving product quality has become paramount, leading to increasingly stringent requirements for heat treatment temperature control. However, due to the increasing size of ring forgings, the difficulty of furnace temperature control has also increased. Single PID temperature control can no longer meet the high-quality temperature control requirements of the process. To improve efficiency during the heating stage, the proportional gain needs to be increased, but this parameter can cause temperature oscillations during the holding stage, potentially leading to internal stress cracks in the forgings. Furthermore, traditional resistance furnaces rely on single-point thermocouples to monitor the temperature at the center of the furnace, which cannot detect temperature gradients in the height direction, resulting in overheating at the bottom and underheating at the top of the workpiece. Existing over-temperature protection is mostly implemented through PLC software, with a response delay of ≥2 seconds, resulting in a high product scrap rate.

[0003] In summary, there is an urgent need for a dual-PID temperature control system for the heat treatment of large forgings, which can improve temperature control accuracy, resolve the fundamental contradiction between heating efficiency and heat preservation stability, and establish multiple safety protection mechanisms. Utility Model Content

[0004] The purpose of this invention is to provide a heat treatment resistance furnace with a dual-PID temperature control system to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a heat treatment resistance furnace with a dual-PID temperature control system, comprising an all-fiber furnace body, heating resistance wires, and a temperature control system. The all-fiber furnace body is composed of multiple high-temperature resistant fiber modules spliced ​​together, and its inner surface is provided with an embedded groove. Heating resistance wires are embedded in the grooves, and the two ends of the heating resistance wires are led out through high-temperature resistant wires. A temperature control thermocouple for main temperature control is provided on one side of the all-fiber furnace body, and an early warning thermocouple for temperature monitoring and an over-temperature thermocouple for safety protection are provided on the other side. The temperature-controlled thermocouple, the warning thermocouple, and the over-temperature thermocouple are all vertically inserted into the side wall of the furnace body, with the probe of the temperature-controlled thermocouple extending to the center area of ​​the furnace chamber. The temperature control system includes: a temperature control module connected to the temperature-controlled thermocouple via a shielded cable, the temperature control module containing a first PID temperature controller; a warning module connected to the warning thermocouple via a shielded cable, the warning module containing a second PID temperature controller; and an over-temperature module connected to the over-temperature thermocouple via a shielded cable. The temperature control module, the warning module, and the over-temperature module are integrated into a control box.

[0006] Furthermore, the heating resistance wire is made of 0Cr27Al7Mo2 material.

[0007] Furthermore, the heating resistance wire adopts a star connection.

[0008] Furthermore, the number of temperature-controlling thermocouples is four, which are vertically distributed along the side wall of the all-fiber furnace body.

[0009] Furthermore, the temperature-controlling thermocouple, the early warning thermocouple, and the over-temperature thermocouple are all type K thermocouples.

[0010] Furthermore, the output terminal of the first PID temperature controller is connected to the power supply control device of the heating resistance wire, which is used to adjust the power of the heating resistance wire according to the measured value of the temperature control thermocouple to control the furnace temperature.

[0011] Furthermore, the output of the second PID temperature controller is connected to the power supply control device of the heating resistance wire, which is used to activate when the furnace temperature reaches the preset temperature value of the early warning module, assisting or replacing the first PID temperature controller to maintain the furnace temperature stability.

[0012] Furthermore, the output terminal of the over-temperature module is connected to the circuit breaker of the power supply circuit, which is used to trigger the circuit breaker to disconnect the power supply circuit when the furnace temperature reaches the over-temperature set value.

[0013] Compared with existing technologies, the beneficial effects of this utility model are as follows: This utility model uses a dual-set PID temperature control system for heat treatment resistance furnaces, adding early warning thermocouples and an early warning temperature control module. The added PID temperature control system primarily ensures smooth temperature control, preventing fluctuations and excessive temperature volatility. The over-temperature thermocouples ensure timely power cut-off in case of over-temperature conditions, preventing product scrapping. This design improves equipment temperature control performance, increases product first-pass yield and pass rate, ensures normal equipment operation, saves energy, reduces production energy costs, enhances the company's competitiveness in the industry, and improves social benefits. Furthermore, by using four vertically distributed temperature control thermocouples to monitor the vertical temperature field of the furnace body in real time, combined with the current-equalizing characteristics of the star-connected resistance wires, it achieves: a temperature difference ≤5℃ along the furnace height, and a temperature field uniformity of 98% between the edge and center areas. This solves the problem of overheating at the bottom and underheating at the top of offshore wind turbine flanges with a height of over 2m, improving the consistency of product mechanical properties. The over-temperature module is then hardwired to the power circuit breaker, with a response time of less than 0.5 seconds. The power is cut off within 0.3 seconds after the over-temperature is triggered. The triple thermocouple redundancy allows the temperature control, early warning, and over-temperature thermocouples to work independently, eliminating the risk of single-point failure. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model;

[0015] Figure 2 This is a flowchart illustrating the process of this utility model.

[0016] In the diagram: 1. All-fiber furnace body, 2. Heating resistance wire, 3. Temperature control thermocouple, 4. Early warning thermocouple, 5. Over-temperature thermocouple, 6. Temperature control module, 7. Early warning module, 8. Over-temperature module, 9. Control box. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings and specific embodiments.

[0018] Please refer to Figure 1-2 This utility model provides a heat treatment resistance furnace with a dual-PID temperature control system, including: a full-fiber furnace body 1, a heating resistance wire 2, and a temperature control system. The full-fiber furnace body 1 is composed of multiple high-temperature resistant fiber modules spliced ​​together, and its inner surface is provided with an embedded groove; the heating resistance wire 2 is embedded in the groove, and the two ends of the heating resistance wire 2 are led out through high-temperature resistant wires; one side of the full-fiber furnace body 1 is provided with a temperature control thermocouple 3 for main temperature control, and the other side is provided with a warning thermocouple 4 for temperature monitoring and an over-temperature thermocouple 5 for safety protection; the temperature control thermocouple 3, the warning thermocouple 4, the over-temperature thermocouple 5, the temperature control thermocouple 4, the temperature monitoring thermocouple 5, the over-temperature thermocouple 6, the temperature control thermocouple 7, the temperature control thermocouple 8, the temperature control thermocouple 9, the temperature control thermocouple 1 ... Both the alarm thermocouple 4 and the over-temperature thermocouple 5 are vertically inserted into the side wall of the furnace body, with the probe of the temperature control thermocouple 3 extending to the center area of ​​the furnace chamber. The temperature control system includes: a temperature control module 6, connected to the temperature control thermocouple 3 via a shielded cable, the temperature control module 6 containing a first PID temperature controller; an alarm module 7, connected to the alarm thermocouple 4 via a shielded cable, the alarm module 7 containing a second PID temperature controller; and an over-temperature module 8, connected to the over-temperature thermocouple 5 via a shielded cable. The temperature control module 6, the alarm module 7, and the over-temperature module 8 are integrated into the control box 9.

[0019] The all-fiber furnace body 1 is constructed from high-temperature resistant 350mm*350mm fiber modules. Heating resistance wires 2 are installed in embedded grooves. Temperature control thermocouples 3 are inserted into the center of the furnace to provide real-time feedback on the temperature of the main temperature zone. Early warning thermocouples 4 monitor the temperature and trigger the second PID system. Over-temperature thermocouples 5 provide safety protection and cut off the power supply when the temperature exceeds the limit. Temperature control module 6 contains a first PID temperature controller to adjust the heating rate. Early warning module 7 contains a second PID temperature controller to maintain temperature stability. Over-temperature module 8 triggers power-off and alarm when the temperature exceeds the limit. Control box 9 integrates all modules and manages the signals uniformly. The temperature control module 6, early warning module 7, and over-temperature module 8 all use Siemens modules, which have strong stability and high temperature accuracy, with an error within 0.2%.

[0020] The heating resistance wire 2 is made of 0Cr27Al7Mo2 material, which improves oxidation resistance by 3 times and can withstand high temperature of 1400℃.

[0021] The heating resistance wire 2 adopts a star connection to balance the three-phase current, avoid local overload, and improve the uniformity of heat distribution.

[0022] The number of temperature control thermocouples 3 is 4, which are vertically distributed along the side wall of the all-fiber furnace body 1, covering the temperature field in the height direction of the furnace body, and measuring temperature at multiple points to solve the problem of vertical temperature deviation of large-height flanges.

[0023] The temperature control thermocouple 3, the early warning thermocouple 4, and the over-temperature thermocouple 5 are all K-type thermocouples, which have good oxidation resistance, strong stability, and accurate potential signals. According to the CQI-9 standard, they need to be replaced every year.

[0024] The output of the first PID temperature controller is connected to the power supply control device of the heating resistance wire 2, and is used to adjust the power of the heating resistance wire 2 according to the measurement value of the temperature control thermocouple 3 to control the furnace temperature.

[0025] The output of the second PID temperature controller is connected to the power supply control device of the heating resistance wire 2, and is used to start when the furnace temperature reaches the preset temperature value of the early warning module 7, to assist or replace the first PID temperature controller in maintaining the furnace temperature stability.

[0026] The output terminal of the over-temperature module 8 is connected to the circuit breaker of the power supply circuit, which is used to trigger the circuit breaker to disconnect the power supply circuit when the furnace temperature reaches the over-temperature set value.

[0027] When using this invention, initial heating begins. The temperature-controlling thermocouple 3 monitors the furnace center temperature in real time and transmits the data to the temperature control module 6. The first PID controller in the temperature control module 6 calculates the output power based on the set process curve, and sends the power signal to the power supply device of the resistance wire 2. The resistance wire heats at the maximum allowable power. If the temperature fluctuation exceeds the PID tolerance, the first PID controller dynamically adjusts the resistance wire power. The temperature-controlling thermocouple 3 provides continuous feedback, forming a closed-loop control to ensure the heating rate meets the process requirements. When the warning thermocouple 4 detects that the temperature reaches the process set value +5℃, it sends a signal to the warning module 7. The warning module 7 activates the second PID controller, taking over temperature control. The second PID parameters aim to reduce fluctuations and suppress temperature oscillations. The power of the resistance wire 2 is then adjusted by the second PID controller to maintain the temperature within the process set value. Over-temperature protection is monitored in real time. The over-temperature thermocouple 5 independently monitors the temperature, ignoring the PID system status. If the temperature exceeds the process allowable upper limit, the over-temperature module 6 immediately triggers the power supply circuit breaker, cutting off the power to the resistance wire 2. Simultaneously, an audible and visual alarm is activated, and the over-temperature event information is recorded. This action is a hard protection, with higher priority than the PID system. After the process is complete, manually stop heating, de-energize resistance wire 2, and allow the furnace to cool naturally. If the over-temperature protection is triggered, the cause of the fault must be manually checked and reset. Before restarting the over-temperature module 6 and the system, it must be confirmed that the temperature has dropped to a safe range.

[0028] The working principle of this utility model is as follows: First, in the initial heating stage of the heat treatment furnace, the temperature is controlled in real time by using the temperature control thermocouple feedback and the first set of PID parameters, which can ensure the heating rate and ensure the smooth progress of the product process.

[0029] The second step involves automatically switching to a second temperature control system when the temperature reaches the process temperature and exceeds it by 5°C (this excess temperature can be adjusted according to process requirements). Utilizing the real-time temperature feedback from the early warning temperature control coupler system, a second PID control system is activated. The PID parameters primarily ensure system temperature stability, preventing excessive fluctuations that could lead to overheating and other defects during the final stages of heat treatment. This design is simple in principle, significantly improves the uniformity of the high-temperature furnace temperature, avoids raw material burn-off caused by localized temperature differences, increases the first-pass yield, reduces production quality costs, enhances the company's core competitiveness, and improves social benefits.

[0030] Furthermore, the furnace body is constructed from all-fiber modules (350mm×350mm) spliced ​​together. Fiber modules facilitate later maintenance, have low cost, and offer good thermal insulation performance.

[0031] Furthermore, all thermocouples are type K thermocouples, with nickel-chromium alloy and nickel-chromium silicon / nickel-chromium alloy as the electrode materials, which increases their oxidation resistance and stability. The output potential signal is stable, but they need to be replaced every year and the operating temperature is below 1400℃.

[0032] Furthermore, when the temperature of the thermocouple is 5°C higher than the process set temperature (the specific temperature can be adjusted), the second set of PID setting parameters will be automatically activated to control the temperature to be lower than the system temperature, thus avoiding large temperature fluctuations.

[0033] Furthermore, when the temperature exceeds the maximum allowable deviation of the process, the over-temperature thermocouple will send a feedback signal to stop the system heating and automatically record the alarm information to prevent product scrap.

[0034] Although embodiments of the present invention have been shown and described, it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, it will be understood by those skilled in the art that all other embodiments obtained by making various changes, modifications, substitutions and alterations to these embodiments without departing from the principles and spirit of the present invention and without creative effort are within the scope of protection of the present invention.

Claims

1. A heat treatment resistance furnace with a dual PID temperature control system, comprising: The all-fiber furnace body (1), heating resistance wire (2), and temperature control system are characterized in that: the all-fiber furnace body (1) is composed of multiple high-temperature resistant fiber modules spliced ​​together, and its inner surface is provided with an embedded groove; the heating resistance wire (2) is embedded in the groove, and the two ends of the heating resistance wire (2) are led out through high-temperature resistant wires; one side of the all-fiber furnace body (1) is provided with a temperature control thermocouple (3) for main temperature control, and the other side is provided with an early warning thermocouple (4) for temperature monitoring and an over-temperature thermocouple (5) for safety protection; the temperature control thermocouple (3), the early warning thermocouple (4), and the over-temperature thermocouple (5) are all The temperature control system is vertically inserted into the side wall of the furnace body, wherein the probe of the temperature control thermocouple (3) extends to the center area of ​​the furnace chamber; the temperature control system includes: a temperature control module (6), which is connected to the temperature control thermocouple (3) via a shielded cable, and the temperature control module (6) includes a first PID temperature controller; an early warning module (7), which is connected to the early warning thermocouple (4) via a shielded cable, and the early warning module (7) includes a second PID temperature controller; and an over-temperature module (8), which is connected to the over-temperature thermocouple (5) via a shielded cable; the temperature control module (6), the early warning module (7), and the over-temperature module (8) are integrated in the control box (9).

2. The heat treatment resistance furnace with a dual PID temperature control system according to claim 1, characterized in that: The heating resistance wire (2) is made of 0Cr27Al7Mo2 material.

3. The heat treatment resistance furnace with a dual PID temperature control system according to claim 1, characterized in that: The heating resistance wire (2) is connected in a star configuration.

4. The heat treatment resistance furnace with a dual PID temperature control system according to claim 1, characterized in that: The number of temperature-controlled thermocouples (3) is 4, which are vertically distributed along the side wall of the all-fiber furnace body (1).

5. The heat treatment resistance furnace with a dual PID temperature control system according to claim 1, characterized in that: The temperature control thermocouple (3), the early warning thermocouple (4), and the overheat thermocouple (5) are all K-type thermocouples.

6. The heat treatment resistance furnace with a dual PID temperature control system according to claim 1, characterized in that: The output of the first PID temperature controller is connected to the power supply control device of the heating resistance wire (2) to adjust the power of the heating resistance wire (2) according to the measured value of the temperature control thermocouple (3) to control the furnace temperature.

7. The heat treatment resistance furnace with a dual PID temperature control system according to claim 6, characterized in that: The output of the second PID temperature controller is connected to the power supply control device of the heating resistance wire (2) and is used to start when the furnace temperature reaches the preset temperature value of the early warning module (7) to assist or replace the first PID temperature controller in maintaining the furnace temperature stability.

8. The heat treatment resistance furnace with a dual PID temperature control system according to claim 7, characterized in that: The output terminal of the over-temperature module (8) is connected to the circuit breaker of the power supply circuit, which is used to trigger the circuit breaker to disconnect the power supply circuit when the furnace temperature reaches the over-temperature set value.

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