Sintering furnace temperature field control method based on element faults

Abstract

A sintering furnace temperature field control method based on element faults comprises the steps that three heating bodies are arranged in a sintering furnace, after a fault of a certain heating body is recognized, the fault type is firstly judged, then the power of the heating body is adjusted and increased according to the fault type, if the resistance value of the heating body is larger than an allowable resistance value, the heating body is damaged, and if the resistance value of the heating body is not larger than an allowable resistance value, the heating body is damaged. Directly neglecting the measurement data of the heating body, and adjusting the power of the heating body according to the stage of the sintering furnace; otherwise, if the numerical value of the temperature measuring device is low, the power of the heating body is adjusted according to the power of the other two heating bodies. According to the control method, the situation that the uniformity of the temperature field becomes poor due to the fact that only the heating body in the temperature measurement abnormal area is adjusted is avoided, the problem that the uniformity of the temperature field of the sintering furnace is difficult to control is solved, the stability of the temperature field in the sintering furnace is improved, and the sintering performance of parts is greatly guaranteed.

Description

Technical Field

[0001] The invention relates to a sintering furnace temperature field control method based on component failure. Background Art

[0002] With the rapid development of new energy vehicles, major automakers are seeking ways to increase the speed of their drive motors. Silicon nitride bearings, with their excellent properties such as self-insulation, self-lubrication, and high-temperature resistance, have become key components for achieving high-speed drive motors in new energy vehicles. High-quality silicon nitride sintering furnaces are crucial for producing high-performance silicon nitride ceramic substrates and bearing balls. Maintaining a uniform and stable internal temperature field is crucial for ensuring the performance of these ceramic bearing ball components.

[0003] Due to the large internal dimensions of industrial sintering furnaces, temperature control is often achieved through the placement of multiple heating elements. Under high temperatures and pressures, many internal structures within the sintering furnace undergo thermal deformation and structural changes. The heating elements in different areas of the sintering furnace experience varying heating conditions, making the probability of failure difficult to achieve uniformity.

[0004] Silicon nitride sintering furnaces contain numerous temperature measuring devices. If one of these devices fails in a high-temperature environment during the sintering process, adjusting the heating element power based on the measured temperature may result in uncorrected temperature deviations within the sintering furnace, leading to a significant decrease in the sintering performance of silicon nitride ceramics. If the temperature measurement data around a heating element is too low, adjustments can be made by increasing the power of that element. However, if the heating element has already failed, increasing the power of that element will not truly achieve temperature regulation and will instead increase the deviation in the internal temperature field. Therefore, targeted temperature field control is necessary. Summary of the Invention

[0005] Aiming at the problem that the temperature field control accuracy in the current high-temperature sintering furnace is not high, the present invention proposes a sintering furnace temperature field control method based on component failure, thereby improving the reliability of the temperature field in the sintering furnace.

[0006] The technical means adopted by the present invention to solve the above problems are: a sintering furnace temperature field control method based on component failure. There are three heating elements in the sintering furnace. After identifying that a heating element has a fault, the type of fault is first determined, and then the power of the heating element is adjusted according to the fault type: if the resistance value of the heating element is greater than the allowable resistance value, the heating element is damaged, and the measurement data of the heating element is directly ignored, and the power of the heating element is adjusted according to the stage of the sintering furnace; otherwise, the value of the temperature measuring device is just low, and the power of this heating element is adjusted according to the power of the other two heating elements.

[0007] Furthermore, when the fault is caused by damage to the heating element, if the sintering furnace is in the insulation stage, the preset fault state fuzzy PID control program is used to fine-tune the power of the heating element based on the power at the time of the fault until the sintering insulation time ends; if the sintering furnace is in the heating stage, the power of the heating element is adjusted according to the position of the heating element.

[0008] Furthermore, when the fuzzy PID control program is used to fine-tune the power of the heating element, the adjustment value P(t) at a certain time t is calculated according to the following formula:

[0009]

[0010] Where: P p N 、P i N 、P d N Control coefficient, and the initial values are P p N =4,P i N =0.05, P d N =0.006; e(t) is the power error of the heating element.

[0011] Furthermore, e(t)=P tar -P ave ,

[0012] Where: P tar P is the preset heating power for heat preservation. ave It is the average power of the heating element when it is working normally.

[0013] Furthermore, P p N =P p +0.5△P p ,

[0014] P i N =P i +0.5△P i ,

[0015] P d N =P d +0.5△P d ,

[0016] Where: P p 、P i 、P d P of the previous time period is p N 、P iN 、P d N Assign its value, and △P p , △P i , △P d They are respectively the values in the fuzzy control rule table corresponding to the error conditions of the heating element.

[0017] Furthermore, ΔP p The fuzzy control rule table is as follows:

[0018]

[0019] ΔP i The fuzzy control rule table is as follows:

[0020]

[0021] ΔP d The fuzzy control rule table is as follows:

[0022]

[0023] Where: ec(t) = e(t) - e(t'), e(t') is the power error of the heating element in the previous time period, and ec(t) is the difference between the power errors of the heating element in two adjacent time periods.

[0024] Furthermore, e(t), ec(t), ΔP p , ΔP i , ΔP d The fuzzy subset is {NB, NM, NS, ZO, PS, PM, PB} = {negative large, negative medium, negative small, zero, positive small, positive medium, positive large}, and ΔP p The corresponding value range is [-5,5], ΔP i The corresponding value range is [0,0.1], ΔP d The corresponding value range is [0,0.001].

[0025] Furthermore, adjusting the power of the heating element according to the position of the heating element means that when the damaged heating element is the heating element p1 or p2 in the symmetrical position, its power is maintained at P1:P2=r1, where r1=0.9~1.05; when the damaged heating element is p3 in the middle position, its power is maintained at P1:P3=r2, where r2=0.6~0.7.

[0026] Furthermore, regulating the power of this heating element according to the power of the other two heating elements means first changing the temperature rise slope of this heating element to make it consistent with the temperature rise slopes of the other two heating elements, and then adjusting the power value of this heating element.

[0027] Furthermore, when adjusting the power value of the heating element, the power of the heating element is adjusted to the average value of the powers of the other two heating elements.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention adjusts the temperature of the heating element according to the actual situation of the heating element, making the adjustment more accurate, thereby better controlling the temperature in the sintering furnace, ensuring a better sintering effect, and further better ensuring the quality of the sintered product.

[0030] 2. The control method of the present invention avoids the situation where the temperature field uniformity deteriorates by simply adjusting the heating element in the temperature measurement abnormality area, solves the problem of difficult control of the temperature field uniformity of the sintering furnace, improves the stability of the temperature field inside the sintering furnace, and greatly guarantees the sintering performance of the parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the distribution of heating elements and temperature measuring devices in the sintering furnace of Example 1;

[0032] Figure 2 Schematic diagram of a sintering furnace temperature field control method based on component failure in Example 1. DETAILED DESCRIPTION

[0033] The present invention is further described below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are schematic, not actual, representations. They should not be construed as limiting this patent. To better illustrate the embodiments of the present invention, some components in the accompanying drawings may be omitted, enlarged, or reduced in size, and do not represent the actual dimensions of the products. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted from the accompanying drawings.

[0034] Example 1

[0035] A method for controlling the temperature field of a sintering furnace based on component failure, such as Figure 1As shown, there are three heating elements p1, p2, and p3 in the sintering furnace, of which p1 and p2 are symmetrically arranged in the furnace, and p3 is located in the middle. Temperature measuring devices t1, t2, and t3 are respectively set near the three heating elements p1, p2, and p3, so that the three temperature measuring devices t1, t2, and t3 are used to measure the temperatures of the three heating elements p1, p2, and p3 respectively. When a heating element is identified as having a fault, the fault type is first determined, and then the power of the heating element is adjusted according to the two fault types S1 and S2. If the resistance value of the heating element is greater than the allowable resistance value, the heating element is damaged, which is fault type S1. At this time, the measurement data of the heating element is directly ignored, and the power of the heating element is adjusted according to the stage of the sintering furnace; otherwise, the value of the temperature measuring device is only low, which is fault type S2. At this time, the power of this heating element is adjusted according to the power of the other two heating elements. For fault type S1, different temperature field control methods are adopted according to whether the sintering furnace is in the insulation stage S11 or the heating stage S12.

[0036] In the case of fault S11, the preset fault state fuzzy PID control program is used to fine-tune the power of the heating element based on the power at the time of the fault until the sintering holding time is over. When the fuzzy PID control program is used to fine-tune the power of the heating element, the adjustment value P(t) at a certain time t is calculated according to the following formula:

[0037]

[0038] Where: P p N 、P i N 、P d N Control coefficient, when the fault occurs for the first time, the initial value is selected as P p N =4,P i N =0.05, P d N =0.006; and e(t) is the power error of the heating element, and e(t) = P tar -P ave , where: P tar P is the preset heating power for heat preservation. ave It is the average power of the heating element when it is working normally.

[0039] Starting from the second moment, the control coefficient P p N 、P i N 、P d N The calculation method is:

[0040] P p N =P p +0.5△P p ,

[0041] P i N =P i +0.5△P i ,

[0042] P d N =P d +0.5△P d ,

[0043] Where: P p 、P i 、P d P of the previous time period is p N 、P i N 、P d N Assign its value, and △P p , △P i , △P d are the values in the fuzzy control rule table corresponding to the error of the heating element, and

[0044] ΔP p The fuzzy control rule table is as follows:

[0045]

[0046] ΔP i The fuzzy control rule table is as follows:

[0047]

[0048] ΔP d The fuzzy control rule table is as follows:

[0049]

[0050] Where: ec(t) = e(t) - e(t'), e(t') is the power error of the heating element in the previous time period, that is, e(t') is the e(t) value of the previous time period, and ec(t) is the difference between the power errors of the heating element in two adjacent time periods. In the above table, e(t), ec(t), ΔP p , ΔP i , ΔP dThe fuzzy subsets are all {NB, NM, NS, ZO, PS, PM, PB} = {negative large, negative medium, negative small, zero, positive small, positive medium, positive large}. In practical applications, the actual range of e(t) is [-0.01P tar ,0.01P tar ], the actual range of ec(t) is [-0.005P tar ,0.005P tar ], and ΔP p The actual value range is [-5,5], ΔP i The actual value range is [0,0.1], ΔP d The actual value range of is [0,0.001]. It should be noted here that the values of negative large, negative medium, negative small, zero, positive small, positive medium, and positive large are selected relative to the actual value range of each parameter. For example, for ΔP p , since its actual value range is [-5,5], the negative value can be -5, the negative value can be -2.5, the negative value can be -1.5, the zero value can be 0, the positive value can be 1.5, the positive value can be 2.5, and the positive value can be 5; for ΔP i , since its actual value range is [0,0.1], the negative large value can be 0, the negative medium value can be 0.025, the negative small value can be 0.04, the zero value can be 0.05, the positive small value can be 0.06, the positive medium value can be 0.075, and the positive large value can be 0.1.

[0051] For example, it is calculated that e(t) = -0.01P tar ,ec(t)=-0.005P tar , that is, the values of e(t) and ec(t) are both negative, that is, NB. Through the above fuzzy control rule table, we can get ΔP p =PB,ΔP i =NB,ΔP d =PS, according to ΔP p , ΔP i , ΔP d The value range of ΔP p =5,ΔP i =0, ΔP d =0.00067, and then the adjustment value P(t) at this moment is calculated.

[0052] For fault S12, when the damaged heating element is the heating element p1 or p2 in the symmetrical position, its power is maintained at P1:P2=r1, where r1=0.9~1.05; when the damaged heating element is p3 in the middle position, its power is maintained at P1:P3=r2, where r2=0.6~0.7.

[0053] For fault S2, first modify the heating element with the lower value to match the heating elements' heating slopes. If there is a certain difference between the heating elements' heating slopes, such as one with k1 and the other with k2, modify it to (k1+k2) / 2. Then adjust the power of this heating element to the average of the other two.

[0054] The above embodiments are only for the purpose of illustrating the present invention, and are not intended to limit the present invention. Those skilled in the art may make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also fall within the scope of protection of the present invention, and the scope of protection of the present invention should be defined by the claims.

Claims

1. A method for controlling the temperature field of a sintering furnace based on component failure, characterized in that: There are three heating elements in the sintering furnace. After identifying that a certain heating element has a fault, the first step is to determine the type of fault, and then adjust the power of the heating element according to the fault type: if the resistance value of the heating element is greater than the allowable resistance value, the heating element is damaged, and the measurement data of the heating element is directly ignored, and the power of the heating element is adjusted according to the stage of the sintering furnace; otherwise, the value of the temperature measuring device is simply low, and the power of this heating element is adjusted according to the power of the other two heating elements.

2. The method for controlling the temperature field of a sintering furnace based on component failure according to claim 1, wherein: When the fault is caused by damage to the heating element, if the sintering furnace is in the insulation stage, the preset fault state fuzzy PID control program is used to fine-tune the power of the heating element based on the power at the time of the fault until the sintering insulation time is over; If the sintering furnace is in the heating stage, the power of the heating element is adjusted according to the position of the heating element.

3. The method for controlling the temperature field of a sintering furnace based on component failure according to claim 2, wherein: When the fuzzy PID control program is used to fine-tune the power of the heating element, the adjustment value P(t) at a certain time t is calculated according to the following formula: Where: P p N 、P i N 、P d N Control coefficient, and the initial values are P p N =4,P i N =0.05, P d N =0.006; e(t) is the power error of the heating element.

4. The method for controlling the temperature field of a sintering furnace based on component failure according to claim 3, wherein: e(t)=P tar -P ave , Where: P tar P is the preset heating power for heat preservation. ave It is the average power of the heating element when it is working normally.

5. The method for controlling the temperature field of a sintering furnace based on component failure according to claim 4, wherein: P p N =P p +0.5△P p , P i N =P i +0.5△P i , P d N =P d +0.5△P d , Where: P p 、P i 、P d P of the previous time period is p N 、P i N 、P d N Assign its value, and △P p , △P i , △P d They are respectively the values in the fuzzy control rule table corresponding to the error conditions of the heating element.

6. The method for controlling the temperature field of a sintering furnace based on component failure according to claim 5, wherein: ΔP p The fuzzy control rule table is as follows: ΔP i The fuzzy control rule table is as follows: ΔP d The fuzzy control rule table is as follows: Where: ec(t) = e(t) - e(t'), e(t') is the power error of the heating element in the previous time period, and ec(t) is the difference between the power errors of the heating element in two adjacent time periods.

7. The method for controlling the temperature field of a sintering furnace based on component failure according to claim 6, wherein: e(t), ec(t), ΔP p , ΔP i , ΔP d The fuzzy subset is {NB, NM, NS, ZO, PS, PM, PB} = {negative large, negative medium, negative small, zero, positive small, positive medium, positive large}, and ΔP p The corresponding value range is [-5,5], ΔP i The corresponding value range is [0,0.1], ΔP d The corresponding value range is [0,0.001].

8. The method for controlling the temperature field of a sintering furnace based on component failure according to claim 2, wherein: Adjusting the power of the heating element according to the position of the heating element means that when the damaged heating element is the heating element p1 or p2 in the symmetrical position, its power is maintained at P1:P2=r1, where r1=0.9~1.05; when the damaged heating element is p3 in the middle position, its power is maintained at P1:P3=r2, where r2=0.6~0.

7.

9. The method for controlling the temperature field of a sintering furnace based on component failure according to claim 1, wherein: To adjust the power of the heating element according to the power of the other two heating elements means to first change the temperature rise slope of the heating element to make it consistent with the temperature rise slopes of the other two heating elements, and then adjust the power value of the heating element.

10. The method for controlling the temperature field of a sintering furnace based on component failure according to claim 9, wherein: When adjusting the power value of a heating element, the power of the heating element is adjusted to the average power of the other two heating elements.

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