An on-line monitoring system for an external heating sintering furnace

Abstract

The present application relates to sintering furnace technical field, specifically to an online monitoring system of external heating type sintering furnace, including controller, heating resistance wire, temperature sensor, current transformer and voltage sampling module connected in the heating resistance wire circuit, characterized in that, the aging resistance threshold of heating resistance wire is set; the controller obtains the data of heating resistance wire based on temperature sensor, current transformer and voltage sampling module and carries out pretreatment, and obtains feature data set; the feature data set includes cold state resistance before sintering, cold state resistance after sintering, hot state resistance when sintering, cold state temperature and hot state temperature; the relationship between the resistance value change of heating resistance wire and sintering temperature and sintering time is monitored respectively, and the possibility of heating resistance wire melting during sintering is measured by predicting the resistance value change through sintering temperature and sintering time respectively, so that heating resistance wire can be checked and replaced in time, and the sintering furnace can be prevented from being damaged greatly.

Description

Technical Field

[0001] This invention relates to the field of sintering furnace technology, and more specifically to an online monitoring system for an externally heated sintering furnace. Background Technology

[0002] The monitoring system of the sintering furnace is crucial to ensuring stable sintering processes and qualified product quality. It acts like a comprehensive "nervous system," sensing, analyzing, and controlling every critical aspect of the sintering process in real time.

[0003] Currently, in existing technologies, the monitoring of sintering furnaces mainly focuses on temperature control, and the temperature of the sintering furnace is provided by the heating resistance wire. The temperature of the sintering furnace can be detected simply by monitoring the heating resistance wire.

[0004] A search revealed that Chinese invention patent application number 202311779966.5 discloses a temperature control system based on a vacuum sintering furnace, including a data acquisition unit, a data analysis unit, an anomaly analysis unit, and an information output unit. However, this application has the following shortcomings: the temperature monitoring and control system can only monitor sintering furnaces that have already malfunctioned, and cannot prevent malfunctions from occurring. For example, if the heating resistance wire of the sintering furnace melts due to aging, it can only be detected at the moment the heating resistance wire melts, and the melting phenomenon cannot be prevented.

[0005] Therefore, there is an urgent need for a sintering furnace monitoring system that can prevent the melting of heating resistance wires.

[0006] The purpose of this invention is to solve the problems mentioned above. Summary of the Invention

[0007] In view of the above-mentioned shortcomings of the existing technology, the present invention provides an online monitoring system for an externally heated sintering furnace, which can effectively solve the existing problems.

[0008] To achieve the above objectives, the present invention provides the following technical solution: This invention provides an online monitoring system for an externally heated sintering furnace, comprising a controller, a heating resistance wire, a temperature sensor, and a current transformer and a voltage sampling module connected to the heating resistance wire circuit. The system is characterized by setting an aging resistance threshold for the heating resistance wire; the controller acquires data from the heating resistance wire based on the temperature sensor, current transformer, and voltage sampling module, and performs preprocessing to obtain a feature dataset; the feature dataset includes cold resistance before sintering, cold resistance after sintering, hot resistance during sintering, cold temperature, hot temperature, sintering time, cold resistance change value, extreme value of cold resistance change, cold resistance change threshold, resistance temperature coefficient, resistance temperature coefficient change value, extreme value of resistance temperature coefficient change, and resistance temperature coefficient change threshold; the feature dataset is analyzed to obtain a condition dataset; the condition dataset includes: when the cold resistance before and after sintering exceeds the aging resistance threshold, the heating resistance wire is repaired or replaced; when the extreme value of the cold resistance change exceeds the cold resistance change threshold, the heating resistance wire is repaired or replaced; when the extreme value of the resistance temperature coefficient change during sintering exceeds the resistance temperature coefficient change threshold, the heating resistance wire is repaired or replaced after shutdown.

[0009] Furthermore, the current transformer and voltage sampling module are used to repeatedly acquire the cold resistance of the heating resistance wire before sintering. Cold resistance after sintering Hot resistance during sintering The temperature sensor is used to repeatedly obtain the cold temperature of the heating resistance wire. Hot temperature The controller is used to record the sintering time multiple times. The aging resistance threshold of the heating resistance wire It is 90%-93% of the original resistance value of the heating resistance wire.

[0010] Furthermore, the heating resistance wire is made of nickel-chromium alloy wire.

[0011] Furthermore, when or When the cold resistance before and after sintering exceeds the aging resistance threshold, it is determined that the resistance exceeds the threshold value.

[0012] Furthermore, the change in cold resistance value The expression is: The extreme value of the cold resistance change is ,in The cold resistance change value during the nth sintering operation; the cold resistance change threshold is... ,in This refers to the sintering time for the current sintering operation.

[0013] Furthermore, when When the extreme value of the cold resistance change before sintering exceeds the threshold value of the cold resistance change, it is determined that the value of the extreme value of the cold resistance change before sintering exceeds the threshold value of the cold resistance change.

[0014] Furthermore, the temperature coefficient of resistance The expression is or .

[0015] Furthermore, the change in the temperature coefficient of resistance The expression is The extreme value of the temperature coefficient of resistance is... ,in The change in the temperature coefficient of resistance during the nth sintering operation; the threshold value for the change in the temperature coefficient of resistance is... .

[0016] Furthermore, when When the extreme value of the change in the temperature coefficient of resistance during sintering exceeds the threshold value of the change in the temperature coefficient of resistance, it is determined that the extreme value of the change in the temperature coefficient of resistance during sintering is exceeded.

[0017] Furthermore, it also includes the following steps:

[0018] S1: Set the aging resistance threshold of the heating resistance wire to 92% of the original resistance value of the heating resistance wire; S2: Each time the sintering furnace is used, characteristic data is acquired through the current transformer, voltage sampling module, temperature sensor and controller; S3: When the resistance of the heating resistance wire is less than 93% of the original resistance of the heating resistance wire, the controller is used to preprocess the feature data to generate a feature dataset. S4: Compare the cold resistance before sintering or the cold resistance after sintering in the feature dataset with the aging resistance threshold of the heating resistance wire and generate a condition dataset. If the cold resistance before sintering or the cold resistance after sintering is less than or equal to the aging resistance threshold, then repair or replace the heating resistance wire; otherwise, proceed to S5. S5: Compare the extreme value of the cold resistance change before sintering with the threshold value of the cold resistance change in the feature dataset and generate a condition dataset. If the extreme value of the cold resistance change is less than or equal to the threshold value of the cold resistance change, then repair or replace the heating resistance wire; otherwise, proceed to S6. S6: Start the heating resistance wire to perform sintering operation. Compare the extreme value of the change in resistance temperature coefficient during sintering with the threshold value of the change in resistance temperature coefficient in the feature dataset and generate a condition dataset. If the extreme value of the change in resistance temperature coefficient during sintering is less than or equal to the threshold value of the change in resistance temperature coefficient, stop the machine for maintenance and replace the heating resistance wire; otherwise, continue the sintering operation.

[0019] Beneficial effects

[0020] The technical solution provided by this invention has the following advantages compared with known public technologies: By monitoring the relationship between the resistance change of the heating resistance wire and sintering temperature and sintering time, and by predicting the resistance change based on sintering temperature and sintering time, the possibility of the heating resistance wire melting during sintering can be assessed. This allows for timely inspection and replacement of the heating resistance wire, preventing significant damage to the sintering furnace. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0022] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0023] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0024] It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other.

[0025] It should be noted that the concepts of "first" and "second" mentioned in this disclosure are used only to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0026] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0027] This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] The present invention will be further described below with reference to embodiments.

[0029] Example:

[0030] An online monitoring system for an externally heated sintering furnace, such as Figure 1 As shown,

[0031] Heating components in sintering furnaces generally use resistance heating wires, which are low in cost and widely used. However, the aging rate of resistance heating wires accelerates during operation, causing resistance drift. In severe cases, this can lead to wire meltdown and damage to the sintering furnace. Therefore, it is necessary to prevent the aging of resistance heating wires and replace them in a timely manner. This requires monitoring and prevention of resistance heating wires. The monitoring method varies depending on the material of the resistance heating wire. This application takes a resistance heating wire made of nickel-chromium alloy as an example. It should be noted that research shows that the cold resistance of nickel-chromium alloys (such as 80Ni-20Cr) decreases during accelerated life testing. This phenomenon is related to the loss of chromium (Cr) in the alloy. The loss of chromium significantly changes the temperature coefficient of resistance of the alloy and may trigger an internal ordering transformation (such as the CrNi3 ordered phase), resulting in an initial increase in resistivity, which then tends to stabilize. In addition, although the cold resistance decreases, the resistance of the alloy at the hot state (operating temperature) changes very little. This seemingly contradictory phenomenon is attributed to the fact that the loss of chromium leads to a significant increase in the temperature coefficient of resistance of the alloy.

[0032] It should also be noted that when monitoring the heating resistance wire of the sintering furnace, the aging resistance threshold of the heating resistance wire needs to be set first. That is, once the resistance value of the heating resistance wire falls below the aging resistance threshold... This indicates that the heating resistance wire is severely aged, with a large resistance drift, requiring timely replacement. In practical production and daily life, a 10% fluctuation in the resistance value of the heating resistance wire is generally considered a sign of severe aging. The preferred aging resistance threshold of the heating resistance wire in this invention... The resistance value is 92% of the original heating resistance wire, ensuring that the heating resistance wire will not age and melt while controlling the replacement frequency.

[0033] The monitoring system includes a controller, a heating resistance wire, a temperature sensor, and current transformers and voltage sampling modules connected to the heating resistance wire circuit. The current and voltage in the circuit are monitored by the current transformers and voltage sampling modules connected to the heating resistance wire circuit, respectively. Then, the resistance of the heating resistance wire is measured by the controller, thereby determining the cold resistance of the heating resistance wire before sintering, the hot resistance during sintering, and the cold resistance after cooling to room temperature after sintering. By observing the resistance change of the heating resistance wire in one sintering operation, the degree of aging of the heating resistance wire can be determined.

[0034] Specifically, the controller acquires data from the heating resistance wire based on temperature sensors, current transformers, and voltage sampling modules, and performs preprocessing to obtain a feature dataset. The feature dataset is then analyzed to obtain a condition dataset. It is worth noting that the feature dataset is obtained by integrating and analyzing the basic data monitored and performing preliminary calculations to obtain intermediate values, which are then compared with the aging resistance threshold to generate the corresponding condition dataset.

[0035] The basic data in the feature dataset includes the cold resistance of the heating resistance wire before sintering. Cold resistance after sintering Hot resistance during sintering The cold temperature of the heating resistance wire Hot temperature sintering time for each sintering operation By collecting basic data and then analyzing and processing the basic data and aging resistance threshold, intermediate values ​​of characteristic data are obtained. These intermediate values ​​include cold resistance changes. Extreme values ​​of cold resistance change Threshold for cold resistance change Temperature coefficient of resistance Temperature coefficient of resistance change Extreme values ​​of temperature coefficient of resistance Threshold for temperature coefficient of resistance change ; The specific calculation scheme for the above intermediate value is as follows: Cold resistance change value The expression is: ,in The cold resistance before sintering in the nth sintering operation. The cold resistance after sintering in the nth sintering operation. Let n be the sintering time for the nth sintering operation. The cold resistance change value during the nth sintering operation is determined by the principle of obtaining the change in resistance per unit time during one sintering operation, i.e., the relationship between the change in resistance and time during one sintering operation. Temperature coefficient of resistance The expression is or ,in Let be the hot resistance during the nth sintering operation. The principle is that there are two temperature coefficients of resistance in a single sintering operation: one from room temperature to operating temperature, and the other from operating temperature to room temperature. The hot resistance values ​​are equal during sintering, but their cold resistance values ​​are not equal. This represents the relationship between resistance change and temperature during a single sintering operation; the change in the temperature coefficient of resistance... The expression is The actual monitored hot and cold temperatures (i.e., room temperature) are different in each sintering operation. However, the hot temperature needs to be raised to a certain temperature in each sintering operation, and the cold temperature of the sintering furnace after each sintering operation remains unchanged. In addition, the hot and cold temperatures in each sintering operation are very different. Therefore, for the sake of calculation convenience, it can be simplified to the hot and cold temperatures being equal in each sintering operation. The extreme values ​​of cold resistance change are The extreme value of the temperature coefficient of resistance is ,in For the change in resistance temperature coefficient during the nth sintering operation, it is important to note that the extreme values ​​of cold resistance change and resistance temperature coefficient change are both selected from a set of data, meaning that data is left for reference after each sintering operation. The data is generated by the heating resistance wire itself, which is more direct and effective for subsequent processing. However, to determine whether the heating resistance wire is aging, a prerequisite is required. Based on the previously set aging resistance threshold of 92% of the original heating resistance wire's resistance value, the prerequisite for judgment is set to when the resistance value of the heating resistance wire is below 93% of the original heating resistance wire's resistance value. The controller's comparison module should be activated as close as possible to the aging resistance threshold to ensure the speed of the sintering operation in the early stage of the sintering furnace and the safety of the later stage of the sintering furnace operation. The specific comparison scheme is as follows: when or If the cold resistance before and after sintering exceeds the aging resistance threshold, the heating resistance wire is repaired or replaced; otherwise, the cold resistance change threshold is calculated and compared with the extreme value of the cold resistance change. when If the extreme value of the cold resistance change before sintering exceeds the threshold value, the heating resistance wire should be repaired or replaced; otherwise, sintering should proceed. It should be noted that when... If the cold resistance change value is not recorded in the past, it means that the cold resistance of the heating resistance wire after sintering will still not exceed the aging resistance threshold range after this sintering operation. Therefore, it may cause the heating resistance wire to melt, and the staff needs to check, repair and replace the heating resistance wire in time. when If the extreme value of the change in the temperature coefficient of resistance during sintering exceeds the threshold value, the machine must be stopped and the heating resistance wire repaired and replaced. Otherwise, the sintering process continues until completion. It should be noted that when... If the resistance temperature coefficient change value is not present in the previous records, it means that the cold resistance of the heating resistance wire after sintering will still not exceed the aging resistance threshold range. Therefore, it may cause the heating resistance wire to melt, and the staff needs to check, repair and replace the heating resistance wire in time.

[0036] An online monitoring system for an externally heated sintering furnace further includes the following steps: S1: Set the aging resistance threshold of the heating resistance wire to 92% of the original resistance value of the heating resistance wire; S2: Each time the sintering furnace is used, characteristic data is acquired through the current transformer, voltage sampling module, temperature sensor and controller; S3: When the resistance of the heating resistance wire is less than 93% of the original resistance of the heating resistance wire, the controller is used to preprocess the feature data to generate a feature dataset. S4: Compare the cold resistance before sintering or the cold resistance after sintering in the feature dataset with the aging resistance threshold of the heating resistance wire and generate a condition dataset. If the cold resistance before sintering or the cold resistance after sintering is less than or equal to the aging resistance threshold, then repair or replace the heating resistance wire; otherwise, proceed to S5. S5: Compare the extreme value of the cold resistance change before sintering with the threshold value of the cold resistance change in the feature dataset and generate a condition dataset. If the extreme value of the cold resistance change is less than or equal to the threshold value of the cold resistance change, then repair or replace the heating resistance wire; otherwise, proceed to S6. S6: Start the heating resistance wire, compare the extreme value of the change in resistance temperature coefficient during sintering with the threshold value of the change in resistance temperature coefficient in the feature dataset, and generate a condition dataset. If the extreme value of the change in resistance temperature coefficient during sintering is less than or equal to the threshold value of the change in resistance temperature coefficient, stop the machine for maintenance and replace the heating resistance wire; otherwise, continue the sintering operation.

[0037] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. An online monitoring system for an externally heated sintering furnace, comprising a controller, a heating resistance wire, a temperature sensor, and a current transformer and a voltage sampling module connected to the heating resistance wire circuit, characterized in that, Set the aging resistance threshold for the heating resistance wire; The controller acquires data from the heating resistance wire based on temperature sensors, current transformers, and voltage sampling modules, and performs preprocessing to obtain a feature dataset. The feature dataset includes cold resistance before sintering, cold resistance after sintering, hot resistance during sintering, cold temperature, hot temperature, sintering time, cold resistance change value, extreme value of cold resistance change, cold resistance change threshold, resistance temperature coefficient, resistance temperature coefficient change value, resistance temperature coefficient change extreme value, and resistance temperature coefficient change threshold. The feature dataset is analyzed and processed to obtain the condition dataset; The conditional dataset includes: If the cold resistance before and after sintering exceeds the aging resistance threshold, the heating resistance wire should be repaired or replaced. When the extreme value of the cold resistance change exceeds the threshold value of the cold resistance change, the heating resistance wire should be repaired or replaced. If the extreme value of the temperature coefficient of resistance change during sintering exceeds the threshold value, the heating resistance wire should be repaired and replaced after shutdown.

2. The online monitoring system for an externally heated sintering furnace according to claim 1, characterized in that, The current transformer and voltage sampling module are used to repeatedly acquire the cold resistance of the heating resistance wire before sintering. Cold resistance after sintering Hot resistance during sintering ; The temperature sensor is used to repeatedly obtain the cold temperature of the heating resistance wire. Hot temperature ; The controller is used to record the sintering time multiple times. ; The aging resistance threshold of the heating resistance wire It is 90%-93% of the original resistance value of the heating resistance wire.

3. The online monitoring system for an externally heated sintering furnace according to claim 2, characterized in that, The heating resistance wire is made of nickel-chromium alloy wire.

4. The online monitoring system for an externally heated sintering furnace according to claim 3, characterized in that, when or When the cold resistance before and after sintering exceeds the aging resistance threshold, it is determined that the resistance exceeds the threshold value.

5. The online monitoring system for an externally heated sintering furnace according to claim 3, characterized in that, The change in cold resistance The expression is: ; The extreme value of the cold resistance change is ,in This represents the change in cold resistance during the nth sintering operation. The threshold value for cold resistance change is ,in This refers to the sintering time for the current sintering operation.

6. The online monitoring system for an externally heated sintering furnace according to claim 5, characterized in that, when When the extreme value of the cold resistance change before sintering exceeds the threshold value of the cold resistance change, it is determined that the value of the extreme value of the cold resistance change before sintering exceeds the threshold value of the cold resistance change.

7. The online monitoring system for an externally heated sintering furnace according to claim 3, characterized in that, The temperature coefficient of resistance The expression is or .

8. The online monitoring system for an externally heated sintering furnace according to claim 7, characterized in that, The change value of the temperature coefficient of resistance The expression is ; The extreme value of the temperature coefficient of resistance is ,in The change in the temperature coefficient of resistance during the nth sintering operation; The threshold value for the change in the temperature coefficient of resistance is .

9. The online monitoring system for an externally heated sintering furnace according to claim 8, characterized in that, when When the extreme value of the change in the temperature coefficient of resistance during sintering exceeds the threshold value of the change in the temperature coefficient of resistance, it is determined that the extreme value of the change in the temperature coefficient of resistance during sintering is exceeded.

10. An online monitoring system for an externally heated sintering furnace according to any one of claims 4-9, characterized in that, It also includes the following steps: S1: Set the aging resistance threshold of the heating resistance wire to 92% of the original resistance value of the heating resistance wire; S2: Each time the sintering furnace is used, characteristic data is acquired through the current transformer, voltage sampling module, temperature sensor and controller; S3: When the resistance of the heating resistance wire is less than 93% of the original resistance of the heating resistance wire, the controller is used to preprocess the feature data to generate a feature dataset. S4: Compare the cold resistance before sintering or the cold resistance after sintering in the feature dataset with the aging resistance threshold of the heating resistance wire and generate a condition dataset. If the cold resistance before sintering or the cold resistance after sintering is less than or equal to the aging resistance threshold, then repair or replace the heating resistance wire; otherwise, proceed to S5. S5: Compare the extreme value of the cold resistance change before sintering with the threshold value of the cold resistance change in the feature dataset and generate a condition dataset. If the extreme value of the cold resistance change is less than or equal to the threshold value of the cold resistance change, then repair or replace the heating resistance wire; otherwise, proceed to S6. S6: Start the heating resistance wire to perform sintering operation. Compare the extreme value of the change in resistance temperature coefficient during sintering with the threshold value of the change in resistance temperature coefficient in the feature dataset and generate a condition dataset. If the extreme value of the change in resistance temperature coefficient during sintering is less than or equal to the threshold value of the change in resistance temperature coefficient, stop the machine for maintenance and replace the heating resistance wire; otherwise, continue the sintering operation.

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