Thermocouple calibrating furnace and method for calibrating a thermocouple to be tested

Abstract

The present application relates to thermocouple calibration technical field, specifically relates to a kind of thermocouple calibration furnace and the thermocouple calibration method of being detected.The present application provides a kind of thermocouple calibration furnace, including furnace body, front furnace plug, rear furnace plug and at least one temperature control thermocouple;The detection cavity that passes through the furnace body is equipped in the furnace body, one end of the detection cavity is front furnace mouth, its other end is rear furnace mouth;The rear furnace plug is equipped with the through-hole corresponding to the temperature control thermocouple one by one along its axial direction, and the straight hole for the thermocouple to be detected is at least one and is inserted into the front furnace plug along its axial direction;The thermocouple calibration furnace further includes the protection tube corresponding to the through-hole one by one.This thermocouple calibration furnace can avoid the thermocouple to be detected to collide with temperature control thermocouple and produce displacement during furnace loading process, ensure that temperature control thermocouple does not appear temperature control deviation, ensure the calibration effect of the thermocouple to be detected.

Description

Technical Field

[0001] This invention relates to the field of thermocouple calibration technology, specifically to a thermocouple calibration furnace and a calibration method for the thermocouple under test. Background Technology

[0002] The preparation work for a common thermocouple calibration furnace before calibrating the thermocouple under test includes: first, inserting the rear furnace plug into the rear furnace opening of the furnace body; then, inserting the temperature-controlled thermocouple into the rear furnace plug and pushing the temperature-controlled thermocouple so that the measuring end of the temperature-controlled thermocouple is located at the center of the heating area along the length of the tubular heating furnace, so as to collect the real-time furnace temperature; next, inserting the front furnace plug into the front furnace opening of the furnace body; and then inserting the thermocouple cluster under test from the front furnace opening of the furnace body so that the measuring end of the thermocouple cluster under test is close to the center of the heating area along the length of the heating area.

[0003] However, because the axes of the temperature-controlling thermocouple and the thermocouple cluster under test are collinear, and the depths of the temperature-controlling thermocouple and the thermocouple cluster under test inserted into the heating area cannot be precisely controlled, the thermocouple cluster under test often collides with the temperature-controlling thermocouple during the furnace loading process, causing the temperature-controlling thermocouple to shift imperceptibly. This results in temperature control deviations in the next calibration, affecting the calibration results. Summary of the Invention

[0004] (I) The problem to be solved by the present invention is that in the traditional thermocouple calibration furnace, the tested thermocouple cluster often collides with the temperature control thermocouple during the furnace loading process, causing the temperature control thermocouple to be displaced in a way that is not easily detected, resulting in temperature control deviation in the next calibration and affecting the calibration effect.

[0005] (II) Technical Solution

[0006] A thermocouple calibration furnace includes a furnace body, a front furnace plug, a rear furnace plug, and at least one temperature-controlled thermocouple;

[0007] The furnace body is provided with a detection chamber that runs through the furnace body, one end of the detection chamber is the front furnace opening, and the other end is the rear furnace opening;

[0008] The rear furnace plug has through holes that correspond one-to-one with the temperature control thermocouples along its axial direction, and the front furnace plug has at least one straight hole along its axial direction for the thermocouple under test to pass through.

[0009] The thermocouple calibration furnace also includes protective tubes that correspond one-to-one with the through holes. In each set of corresponding protective tubes, through holes, and temperature-controlled thermocouples, the protective tube passes through the through hole and extends to the middle position of the detection chamber. The temperature-controlled thermocouple is inserted into the protective tube so that the detection end of the temperature-controlled thermocouple extends into the middle position of the detection chamber.

[0010] When the rear furnace plug and the front furnace plug are respectively inserted into the rear furnace opening and the front furnace opening, the axis of the through hole and the axis of the straight hole are not collinear, so that the temperature control thermocouple inserted into the through hole and the thermocouple under test inserted into the straight hole are misaligned.

[0011] According to one embodiment of the present invention, the axis of the rear furnace plug is not collinear with the through hole on the rear furnace plug, and the straight hole on the front furnace plug is collinear with the axis of the front furnace plug.

[0012] According to one embodiment of the present invention, the straight hole on the front furnace plug is not collinear with the axis of the front furnace plug, and the through hole on the rear furnace plug is collinear with the axis of the rear furnace plug.

[0013] According to one embodiment of the present invention, a plurality of through holes are provided, and the plurality of through holes are evenly distributed around the axis of the rear furnace plug. A plurality of temperature control thermocouples are provided, and the temperature control thermocouples correspond one-to-one with the through holes. The plurality of temperature control thermocouples are connected in parallel with each other.

[0014] According to one embodiment of the present invention, the length of the protective tube is at least half the depth of the detection cavity, such that when the first end of the protective tube extends into the middle position of the detection cavity, the second end of the protective tube is exposed outside the thermocouple calibration furnace.

[0015] The protective tube has multiple graduated holes at one end near the rear furnace plug, and the multiple graduated holes are evenly arranged along the axial direction of the protective tube.

[0016] According to one embodiment of the present invention, the rear furnace plug is provided with a circular hole, the circular hole is collinear with the axis of the rear furnace plug, a small furnace plug is inserted into the circular hole, and the small furnace plug is coaxially provided with a hole for the temperature control thermocouple to pass through.

[0017] According to one embodiment of the present invention, the thermocouple calibration furnace includes a temperature equalization block, the temperature equalization block having an inner cavity, and a plurality of notches for inserting the protective tube being opened on the end face of the temperature equalization block facing the rear furnace plug. The plurality of notches are evenly arranged around the axis of the temperature equalization block, and a central hole for the thermocouple under test to pass through is opened on the end face of the temperature equalization block facing the front furnace plug. A plurality of holes are evenly opened on the side surface of the temperature equalization block around its axis.

[0018] According to one embodiment of the present invention, the thermocouple calibration furnace includes a cleaning tube, which is sleeved inside the testing chamber. One end of the cleaning tube is inserted into the straight hole in the front furnace plug, and the other end is inserted into the round hole in the rear furnace plug.

[0019] A method for calibrating a thermocouple under test, the method comprising the following steps:

[0020] S1: Wrap the heat insulation fiber around the rear furnace plug, and then insert the rear furnace plug into the rear furnace opening of the furnace body;

[0021] S2: Insert each protective tube into the corresponding through hole on the rear furnace plug and push the protective tube to extend into the detection chamber, ensuring that the protective tube is inserted into the predetermined position. Then, fully insert the measuring end of the temperature control thermocouple into the protective tube.

[0022] S3: Wrap the front furnace plug with heat insulation fiber, and then insert the front furnace plug into the front furnace opening of the furnace body;

[0023] S4: Insert the thermocouple cluster to be tested into the straight hole of the front furnace plug and push the thermocouple cluster to be tested to ensure that the thermocouple cluster to be tested extends into the middle position of the detection cavity, so that the temperature control thermocouple and the thermocouple cluster to be tested are staggered, and then confirm the insertion depth of the thermocouple to be tested.

[0024] S5: Use heat-insulating fibers to seal the gaps at the front and rear furnace openings.

[0025] According to one embodiment of the present invention, when the calibration method is used to test a noble metal thermocouple under test, the calibration method further includes:

[0026] Insert the cleaning tube through the straight hole of the front furnace plug between S3 and S4 so that the other end of the cleaning tube extends into the detection chamber of the furnace body and forms an assembly relationship with the rear furnace plug.

[0027] When this calibration method is used to test the base metal thermocouple under test, the calibration method further includes:

[0028] Insert the heat equalization block into the detection chamber from the front furnace opening between S2 and S3, move it to the vicinity of the center position of the detection chamber, then use a tool to rotate the heat equalization block so that the notch on the heat equalization block is aligned with the protective tube, and then continue to push the heat equalization block so that the protective tube is inserted into the notch.

[0029] The beneficial effects of this invention are:

[0030] This invention provides a thermocouple calibration furnace, comprising a furnace body, a front furnace plug, a rear furnace plug, and at least one temperature-controlled thermocouple. The furnace body has a detection chamber penetrating the furnace body, with one end of the detection chamber being the front furnace opening and the other end being the rear furnace opening. The rear furnace plug has through holes corresponding to the temperature-controlled thermocouples along its axial direction, and the front furnace plug has at least one straight hole along its axial direction for the thermocouple under test to pass through. The thermocouple calibration furnace also includes protective tubes corresponding to the through holes. In each set of corresponding protective tubes, through holes, and temperature-controlled thermocouples, the protective tube passes through the through hole and extends to the middle position of the detection chamber. The temperature-controlled thermocouple is inserted into the protective tube so that the detection end of the temperature-controlled thermocouple extends to the middle position of the detection chamber. When the rear furnace plug and the front furnace plug are respectively inserted into the rear furnace opening and the front furnace opening, the axis of the through hole and the axis of the straight hole are not collinear, so that the temperature-controlled thermocouple inserted into the through hole and the thermocouple under test inserted into the straight hole are misaligned.

[0031] Before calibrating the thermocouple under test, first insert the rear furnace plug into the rear furnace opening of the furnace body, then insert the front furnace plug into the front furnace opening of the furnace body. Next, insert each protective tube into the corresponding through hole on the rear furnace plug and push the protective tube to extend into the test chamber, ensuring that the protective tube is inserted into the predetermined position. Then, fully insert the measuring end of the temperature-controlled thermocouple into the protective tube so that the measuring end of the temperature-controlled thermocouple is located in the middle position of the test chamber. Next, pass the thermocouple cluster under test through the straight hole of the front furnace plug so that the measuring end of the thermocouple cluster under test is moved to the middle position of the test chamber. Finally, use heat insulation fiber to seal the gap between the front and rear furnace openings.

[0032] Because the axis of the through hole on the rear furnace plug and the axis of the straight hole on the front furnace plug are not collinear when the rear furnace plug and the front furnace plug are inserted into the rear furnace opening and the front furnace opening respectively, the temperature control thermocouple inserted into the through hole and the thermocouple under test inserted into the straight hole will be misaligned. This avoids the thermocouple under test from colliding with the temperature control thermocouple and being displaced during the furnace loading process. This ensures that the measuring end of the temperature control thermocouple is always in the middle position of the detection cavity, and there will be no temperature control deviation, thus ensuring the calibration effect of the thermocouple under test. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is a front view of the thermocouple calibration furnace provided in Embodiment 1 of the present invention during the calibration of base metal thermocouples;

[0035] Figure 2This is a cross-sectional view of the thermocouple calibration furnace provided in Embodiment 1 of the present invention during the calibration of base metal thermocouples;

[0036] Figure 3 This is an assembly diagram of the temperature-controlled thermocouple, rear furnace plug, protective tube, and temperature equalization block provided in Embodiment 1 of the present invention;

[0037] Figure 4 This is a cross-sectional view of the thermocouple calibration furnace provided in Embodiment 1 of the present invention during the calibration of precious metal thermocouples;

[0038] Figure 5 This is an assembly diagram of the temperature-controlled thermocouple, rear furnace plug, protective tube, front furnace plug, and cleaning tube provided in Embodiment 1 of the present invention;

[0039] Figure 6 This is a structural diagram of the rear furnace plug provided in Embodiment 1 of the present invention;

[0040] Figure 7 This is a cross-sectional view of the rear furnace plug provided in Embodiment 1 of the present invention;

[0041] Figure 8 This is a structural diagram of the temperature equalization block provided in Embodiment 1 of the present invention;

[0042] Figure 9 This is a cross-sectional view of the temperature equalization block provided in Embodiment 1 of the present invention;

[0043] Figure 10 This is a connection diagram of three temperature-controlled thermocouples provided in Embodiment 1 of the present invention.

[0044] Icons: 1. Furnace body; 2. Rear furnace plug; 201. Plug head; 202. Plug body; 203. Through hole; 204. Limiting step; 3. Front furnace plug; 4. Temperature control thermocouple; 5. Temperature equalization block; 501. Notch; 502. Center hole two; 503. Hole body; 504. Inner cavity; 505. Center hole one; 6. Protective tube; 601. Scale hole; 8. Cleaning tube; 9. Small furnace plug; 10. Wiring terminal; 11. Temperature controller; 12. Host computer. Detailed Implementation

[0045] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Example 1:

[0047] like Figures 1-9As shown, Embodiment 1 of the present invention provides a thermocouple calibration furnace, including a furnace body 1, a front furnace plug 3, a rear furnace plug 2, and at least one temperature-controlled thermocouple 4;

[0048] The furnace body 1 is provided with a detection chamber that runs through the furnace body 1. One end of the detection chamber is the front furnace opening, and the other end is the rear furnace opening.

[0049] The rear furnace plug 2 has through holes 203 that correspond one-to-one with the temperature control thermocouple 4 along its axial direction, and the front furnace plug 3 has at least one straight hole along its axial direction for the thermocouple under test to pass through.

[0050] The thermocouple calibration furnace also includes protective tubes 6 that correspond one-to-one with the through holes 203. In each set of corresponding protective tubes 6, through holes 203 and temperature-controlled thermocouples 4, the protective tube 6 passes through the through hole 203 and extends to the middle position of the detection chamber. The temperature-controlled thermocouple 4 is inserted into the protective tube 6 so that the detection end of the temperature-controlled thermocouple 4 extends into the middle position of the detection chamber.

[0051] When the rear furnace plug 2 and the front furnace plug 3 are inserted into the rear furnace opening and the front furnace opening respectively, the axis of the through hole 203 and the axis of the straight hole are not collinear, so that the temperature control thermocouple 4 inserted into the through hole 203 and the thermocouple under test inserted into the straight hole are staggered.

[0052] In this embodiment, before calibrating the thermocouple under test, the rear furnace plug 2 is first inserted into the rear furnace opening of the furnace body 1, then the front furnace plug 3 is inserted into the front furnace opening of the furnace body 1, and then each protective tube 6 is inserted into the corresponding through hole 203 on the rear furnace plug 2 and pushed so that the protective tube 6 extends into the detection chamber, ensuring that the protective tube 6 is inserted into the predetermined position. Then, the measuring end of the temperature-controlled thermocouple 4 is fully inserted into the protective tube 6 so that the measuring end of the temperature-controlled thermocouple 4 is located in the middle position of the detection chamber. Then, the thermocouple cluster under test is passed through the straight hole of the front furnace plug 3 so that the measuring end of the thermocouple cluster under test is moved to the middle position of the detection chamber. Finally, the gap between the front and rear furnace openings is sealed with heat insulation fiber.

[0053] When the rear furnace plug 2 and the front furnace plug 3 are inserted into the rear furnace opening and the front furnace opening, the axis of the through hole 203 on the rear furnace plug 2 and the axis of the straight hole on the front furnace plug 3 are not collinear. In this way, the temperature control thermocouple 4 inserted into the through hole 203 and the thermocouple under test inserted into the straight hole will be misaligned. This avoids the thermocouple cluster under test from colliding with the temperature control thermocouple 4 and causing displacement during the furnace loading process. This ensures that the measuring end of the temperature control thermocouple 4 is always in the middle position of the detection cavity, and there will be no temperature control deviation, thus ensuring the calibration effect of the thermocouple under test.

[0054] In a preferred embodiment, the axis of the rear furnace plug 2 is not collinear with the through hole 203 on the rear furnace plug 2, while the straight hole on the front furnace plug 3 is collinear with the axis of the front furnace plug 3. Thus, when the temperature-controlled thermocouple 4 is inserted into the through hole 203 on the rear furnace plug 2 and extends into the detection chamber, the axis of the temperature-controlled thermocouple 4 is offset from the axis of the detection chamber. Conversely, when the thermocouple cluster under test is inserted from the straight hole on the front furnace plug 3 and extends into the detection chamber, the axis of the thermocouple cluster under test is collinear with the axis of the detection chamber. Therefore, the thermocouple cluster under test and the temperature-controlled thermocouple 4 will avoid each other within the detection chamber, preventing collisions and thus avoiding displacement of the temperature-controlled thermocouple 4 due to collisions. This also avoids temperature control deviations in the temperature-controlled thermocouple 4, ensuring the calibration effect of the tested thermocouple.

[0055] It should be noted that the measuring end of the temperature-controlling thermocouple 4 is located at the center of the detection cavity along the length of the tubular heating furnace to collect the real-time furnace temperature and use the temperature signal as the basis for the temperature control system. However, if the measuring end of the temperature-controlling thermocouple 4 collides with the thermocouple being measured, causing displacement and deviating from the center of the detection cavity, the furnace temperature measured by the temperature-controlling thermocouple 4 will be lower than the actual furnace center temperature, resulting in a temperature control deviation.

[0056] As a preferred embodiment, such as Figure 6 As shown, multiple through holes 203 are provided on the rear furnace plug 2. The multiple through holes 203 are evenly distributed around the axis of the rear furnace plug 2. The axis of the through holes 203 is not collinear with the axis of the rear furnace plug 2. Correspondingly, multiple temperature control thermocouples 4 are also provided. The temperature control thermocouples 4 correspond one-to-one with the through holes 203, and the multiple temperature control thermocouples 4 are connected in parallel.

[0057] It should be noted that the temperature control thermocouple 4 used in previous calibration furnaces was calibrated using a single thermocouple, while in this embodiment, multiple temperature control thermocouples 4 are connected in parallel. The positive and negative terminals of multiple temperature control thermocouples 4 are connected together in parallel through a soft connection to form multiple circuits that measure the temperature simultaneously under the same temperature environment. Using a parallel connection can improve measurement accuracy and reduce measurement errors in the tube furnace.

[0058] Furthermore, in this embodiment, the number of through holes 203 is two, three, or four. Preferably, there are three, and correspondingly, the number of temperature-controlled thermocouples 4 is also three.

[0059] Specifically, a parallel signal mode of three temperature-controlling thermocouples (4) is used as the basis for temperature control, and the method of measuring temperature close to the furnace wall avoids direct collision and interference between the temperature-controlling thermocouples (4) and the thermocouple under test. For example... Figure 10As shown, the positive terminals of the three temperature-controlled thermocouples 4 are connected to form a parallel terminal, and the negative terminals of the three temperature-controlled thermocouples 4 are connected to form a parallel terminal. The parallel terminal is electrically connected to the temperature controller 11, and the temperature controller 11 is signal connected to the host computer 12.

[0060] Preferably, the three temperature-controlled thermocouples 4 are three temperature-controlled thermocouples 4 from the same batch and of the same model. Alternatively, three temperature-controlled thermocouples 4 with extremely similar errors can be selected. Ideally, the three temperature-controlled thermocouples 4 are made from the same roll of thermocouple wire.

[0061] It should be noted that in this embodiment, three temperature-controlled thermocouples 4 are connected in parallel to measure the temperature inside the detection cavity. Compared with using a single temperature-controlled thermocouple 4, its advantages are:

[0062] First, it can improve the accuracy of measurement. By using three identical temperature-controlled thermocouples in parallel, the accuracy of temperature measurement can be improved.

[0063] Second, the measurement spatial range can be expanded: by using three temperature-controlled thermocouples 4 in parallel, the measurement spatial range can be expanded. Each temperature-controlled thermocouple 4 has its own measurement area, but using them in parallel can make the measurement area more extensive.

[0064] Third, it can measure non-uniform temperature fields. Specifically, three temperature-controlled thermocouples 4 measure the temperature at different locations in the middle region of the detection cavity, and obtain a cavity temperature that is closer to the actual temperature by connecting them in parallel.

[0065] It is evident that using three temperature-controlled thermocouples in parallel can improve the accuracy and range of temperature measurement, and play an important role in applications involving non-uniform temperature field measurement, while maintaining the original temperature control system without modification.

[0066] Preferred, such as Figure 3 and Figure 5 As shown, the calibration furnace also includes three protective tubes 6, each corresponding one-to-one with a temperature-controlling thermocouple 4. Specifically, the diameter of the protective tube 6 is slightly smaller than the diameter of the through hole 203 on the rear furnace plug 2 to ensure that the protective tube 6 can pass smoothly through the through hole 203 of the rear furnace plug 2. One end of the protective tube 6 is open, and the other end is closed. It should be noted that the protective tube 6 also serves as an isolation device to prevent the base metal temperature-controlling thermocouple 4 from releasing contaminants into the furnace. Furthermore, the length of the protective tube 6 is greater than half the depth of the detection chamber, such as... Figure 2 or Figure 4As shown, when one end of the protective tube 6 passes through the through hole 203 on the rear furnace plug 2 and extends to the middle position of the detection chamber, the other end of the protective tube 6 is exposed outside the thermocouple calibration furnace. When installing the temperature-controlled thermocouple 4, one end of the protective tube 6 should first pass through the through hole 203 on the rear furnace plug 2 and extend to the middle position of the detection chamber. Then, the temperature-controlled thermocouple 4 should be inserted from the opening of the protective tube 6 and pushed so that the measuring end of the temperature-controlled thermocouple 4 contacts the closed end of the protective tube 6.

[0067] Considering that the installation depth of the temperature-controlled thermocouple 4 is determined by the protective tube 6, and the insertion depth of the protective tube 6 can only be judged by the length of the remaining protective tube 6, subjective judgment by the operator may lead to errors, in this embodiment, multiple graduated holes 601 are provided at the end of the protective tube 6 near the rear furnace plug 2, and the multiple graduated holes 601 are evenly arranged along the axial direction of the protective tube 6. In this way, the length of the exposed protective tube 6 can be calculated by checking the number of graduated holes 601 on the remaining protective tube 6, thereby obtaining the length of the protective tube 6 that extends into the detection cavity. Thus, when the temperature-controlled thermocouple 4 is inserted into the protective tube 6 and in place, the depth of the temperature-controlled thermocouple 4 in the detection cavity can be known, which makes it convenient for the operator to promptly understand whether the temperature-controlled thermocouple 4 has been inserted into the predetermined middle position of the detection cavity.

[0068] In addition, it should be noted that the arrangement of the scale holes 601 on the protective tube 6 is as follows: Figure 3 As shown, the graduation holes 601 are sequentially opened from one end of the protective tube 6 closest to the temperature-controlling thermocouple 4 towards the other end. The number and spacing of the graduation holes 601 need to be calculated. Specifically, it needs to be ensured that when the right end of the protective tube 6 is inserted into place, the rightmost graduation hole 601 on the protective tube 6 is located inside the rear furnace plug 2 and does not exceed the rear furnace plug 2. In this way, contaminants generated in the detection chamber will not enter the protective tube 6 through the graduation holes 601, thus preventing both the escape of contaminants and the overflow of heat through the protective tube 6.

[0069] It should be noted that thermocouples under test are generally divided into precious metal thermocouples and base metal thermocouples. Precious metal thermocouples are made of platinum-rhodium alloy and pure platinum, while base metal thermocouples are made of materials other than precious metal thermocouples, such as nickel-silicon alloy or nickel-chromium alloy.

[0070] Because base metal thermocouples decompose metal ions under the high-temperature environment of the calibration furnace, in principle, after the calibration furnace has tested base metal thermocouples, it is not advisable to directly test precious metal thermocouples under the same conditions to prevent precious metal thermocouples from failing too quickly due to metal ion contamination.

[0071] To prevent precious metal thermocouples from failing too quickly due to metal ion contamination, in this embodiment, when calibrating the precious metal thermocouple, such as... Figure 4 and Figure 5 As shown, a cleaning tube 8 is installed inside the calibration furnace. The test precious metal thermocouple is inserted into the cleaning tube 8 for calibration. The cleaning tube 8 can not only serve as an isolation function to prevent the precious metal thermocouple from failing too quickly due to metal ion contamination, but also serve as a heat storage function.

[0072] Preferred, such as Figure 8 As shown, the rear furnace plug 2 has a circular hole, which is collinear with the axis of the rear furnace plug 2. A small furnace plug 9 is inserted into the circular hole. The small furnace plug 9 has a hole coaxially formed for the temperature control thermocouple 4 to pass through. Three through holes 203 are evenly arranged around the axis of the rear furnace plug 2 on its side. The through holes 203 are not connected to the circular hole. Furthermore, the rear furnace plug 2 includes an integrally formed plug head 201 and a plug body 202. The plug head 201 and the plug body 202 are coaxially arranged. The plug head 201 is cylindrical, and the plug body 202 is frustum-shaped, i.e. Figure 9 As shown, the diameter of the plug 202 gradually decreases from left to right.

[0073] like Figure 4 As shown, before inserting the rear furnace plug 2 into the rear furnace opening of the detection chamber, the plug body 202 needs to be wrapped with insulation cotton. Due to the small taper design of the plug body 202, when it is inserted into the rear furnace opening of the tube furnace with a small amount of insulation cotton, the rear furnace plug 2 has a certain pre-tightening and sealing ability, which can eliminate heat leakage more effectively than traditional furnace plugs.

[0074] Furthermore, it should be explained that the diameter of the cleaning tube 8 is slightly smaller than the diameter of the circular hole inside the rear furnace plug 2, and also slightly smaller than the diameter of the straight hole on the front furnace plug 3. For example... Figure 5 As shown, the cleaning tube 8 can first pass through the straight hole in the front furnace plug 3 until one end of the cleaning tube 8 near the rear furnace plug 2 is inserted into the round hole of the rear furnace plug 2. The straight hole in the front furnace plug 3 and the round hole in the rear furnace plug 2 cooperate to realize the installation and positioning of the cleaning tube 8.

[0075] Preferably, when calibrating base metal thermocouples, such as Figure 1 , Figure 2 and Figure 3 In this embodiment, a temperature equalization block 5 is installed in the testing chamber of the calibration furnace. The temperature equalization block 5 has good heat resistance and heat storage performance, which improves the calibration accuracy of base metal thermocouples.

[0076] Preferred, such as Figure 10As shown, the temperature distribution block 5 is cylindrical in shape, with an inner cavity 504 inside. Three notches 501 for inserting the protective tube 6 are evenly distributed around the axis of the temperature distribution block 5 on its first side end face. A second central hole 502 is also provided on the first side end face of the temperature distribution block 5, positioned along the axis of the temperature distribution block 5, but not connected to the inner cavity 504. Furthermore, a first central hole 505 is provided on the second side end face of the temperature distribution block 5 for the inserted base metal thermocouple, and this first central hole 505 is connected to the inner cavity 504.

[0077] like Figure 2 and Figure 3 As shown, when calibrating a base metal thermocouple, the rear furnace plug 2 is first inserted into the rear furnace opening of the furnace body 1. Then, multiple protective tubes 6 are inserted into multiple through holes 203 of the rear furnace plug 2 and pushed to extend the protective tubes 6 into the detection chamber. At the same time, the insertion depth of the protective tube 6 is calculated based on the number of scale holes 601 exposed on the outside of the protective tube 6 to ensure that the protective tube 6 is inserted into the predetermined position. Then, the measuring end of the temperature control thermocouple 4 is completely inserted into the protective tube 6.

[0078] Then, the temperature equalization block 5 is inserted into the detection chamber from the front furnace opening, and moved to the vicinity of the center position of the detection chamber. Then, the temperature equalization block 5 is rotated with a tool so that the notch 501 on the temperature equalization block 5 is aligned with the protective tube 6. Then, the temperature equalization block 5 is pushed so that the protective tube 6 is inserted into the notch 501. Then, the front furnace plug 3 is wrapped with heat insulation fiber and inserted into the front furnace opening of the furnace body 1. Next, multiple temperature control thermocouples 4 are connected in parallel. Then, the bundled bare metal thermocouple cluster to be tested is inserted into the straight hole of the front furnace plug 3 and pushed until the end of the bare metal thermocouple cluster to be tested passes through the center hole 505 of the temperature equalization block 5 and enters the inner cavity 504 and approaches the inner wall of the inner cavity 504.

[0079] The thermal conductivity of traditional heat-resistant alloy heat spreaders is about 16 W / m·K. In this embodiment, the heat spreader 5 is made of high-density alumina ceramic, and its thermal conductivity is about 25 W / m·K. Therefore, the heat load and heating lag of the heat spreader 5 in this embodiment are smaller. At the same time, its high-temperature resistance will not produce additional oxidation and burn-off. Its cost of use is lower than that of high-temperature alloy heat spreaders.

[0080] In addition, it should be noted that since the depth of the three notches 501 on the temperature equalization block 5 is the same, when the protective tube 6 is inserted into the detection cavity and fully inserted into the notch 501, it can be ensured that the end faces of the three protective tubes 6 extending into the notch 501 are in the same vertical plane. In this way, when the three temperature control thermocouples 4 are inserted, it can be ensured that the ends of the three temperature control thermocouples 4 extending into the detection cavity are in the same cross section. Since the measuring ends of the three temperature control thermocouples 4 are in the same vertical plane, the temperature values ​​measured by the three temperature control thermocouples 4 are approximately the same, and there will be no situation where the furnace temperature measured by the three temperature control thermocouples 4 differs greatly.

[0081] Optionally, multiple holes 503 are evenly distributed around the axis of the side of the heat spreader 5, with the holes 503 close to the central hole 505 and away from the central hole 502. Using the holes 503 as fulcrums, and in conjunction with common tools (such as a 90° bent wire), the position of the heat spreader 5 can be adjusted, facilitating the insertion of the protective tube 6 into the notch 501 of the heat spreader 5, and also facilitating the removal of the heat spreader 5 from the furnace. Specifically, when the position of the heat spreader 5 needs to be adjusted, a bent wire can be inserted into the detection chamber from the front furnace opening, so that the bent part of the wire hooks into the hole 503. Then, rotating or pushing the wire will cause the heat spreader 5 to rotate or translate.

[0082] It should be noted that the previous rear furnace plug was cylindrical, with a diameter the same as the diameter of the rear furnace opening of furnace body 1, so that the rear furnace plug 2 could be just inserted into the rear furnace opening. However, due to the different methods of installing precious metal thermocouples and base metal thermocouples into the calibration furnace, the shape of the rear furnace plug used is different.

[0083] Specifically, the rear furnace plug used for calibrating precious metal thermocouples needs to be adapted to the cleaning tube 8. The rear furnace plug has a hole through which the cleaning tube 8 passes, and the axis of this hole is collinear with the axis of the rear furnace plug. In use, the rear furnace plug is inserted into the rear furnace opening, and then the cleaning tube 8 is passed through the straight hole in the front furnace plug 3 and inserted into the hole on the rear furnace plug. Finally, insulating cotton is used to fill the gap between the outer wall of the cleaning tube 8 and the inner wall of the hole on the rear furnace plug.

[0084] Since the back plug used for calibrating base metal thermocouples does not need to be used with the cleaning tube 8, the center hole on the back plug only needs to be able to allow the temperature control thermocouple 4 to pass through.

[0085] Because the configurations of the back furnace plugs used for calibrating precious metal thermocouples and base metal thermocouples are different, the corresponding back furnace plug needs to be replaced when switching the type of thermocouple to be calibrated, which affects work efficiency.

[0086] In this embodiment, such as Figure 6 and Figure 7As shown, the round hole in the rear furnace plug 2 can be used with the cleaning tube 8, and the through hole 203 on the rear furnace plug 2 can be used with the temperature control thermocouple 4. Therefore, it can be used to calibrate both base metal thermocouples and base metal thermocouples without replacing the rear furnace plug 2, thus improving work efficiency.

[0087] Furthermore, the rear furnace plug 2 also supports the traditional installation structure of a single temperature-controlled thermocouple 4. Specifically, because a limiting step 204 is provided in the circular hole on the left side of the rear furnace plug 2, the limiting step 204 is adapted to the small furnace plug 9, allowing the small furnace plug 9 to fit perfectly into the circular hole. The small furnace plug 9 has a hole along its axis for the temperature-controlled thermocouple 4 to pass through. Therefore, the single temperature-controlled thermocouple 4 in the traditional single-temperature-controlled thermocouple 4 calibration method can pass through the hole in the small furnace plug 9 and enter the testing chamber.

[0088] Preferred, such as Figure 3 As shown, the center of the front furnace plug 3 is provided with a straight hole, which is set along the axis of the front furnace plug 3. The end of the front furnace plug 3 facing the detection chamber is truncated.

[0089] As an alternative embodiment, in this embodiment, the straight hole on the front furnace plug 3 is not collinear with the axis of the front furnace plug 3, while the rear furnace plug 2 has a through hole 203 that is collinear with the axis of the rear furnace plug 2, and the diameter of the through hole 203 is slightly larger than the diameter of the temperature-controlled thermocouple 4. Thus, during measurement, the temperature-controlled thermocouple 4 passes through the through hole 203 of the rear furnace plug 2, making the axis of the temperature-controlled thermocouple 4 collinear with the axis of the detection chamber. Meanwhile, the thermocouple under test passes through the straight hole of the front furnace plug 3 and extends into the detection chamber, bringing it close to the interior of the detection chamber. This offsets the thermocouple under test and the temperature-controlled thermocouple 4, preventing the thermocouple cluster under test from colliding with the temperature-controlled thermocouple 4 during furnace loading and ensuring the calibration effect of the thermocouple under test.

[0090] In summary, the thermocouple calibration furnace in this embodiment optimizes the temperature control accuracy of thermocouple calibration furnaces in the calibration of base metal thermocouples and precious metal thermocouples, reduces the risk of heat leakage from the tubular furnace, reduces foreign metal ion contamination in the furnace, eliminates the risk of burn-out of the temperature equalization block 5, facilitates the control of the insertion depth of the temperature-controlled thermocouple 4, and can adapt and improve traditional old thermocouple calibration furnaces at a lower cost.

[0091] Example 2:

[0092] Embodiment 2 of the present invention provides a method for calibrating a thermocouple under test, the calibration method including a calibration method for a noble metal thermocouple under test and a calibration method for a base metal thermocouple under test;

[0093] The calibration method for the tested precious metal thermocouple includes the following steps:

[0094] Step 1: Wrap the front furnace plug 3 and the rear furnace plug 2 with heat insulation fiber respectively, and then insert the front furnace plug 3 and the rear furnace plug 2 into the front furnace opening and the rear furnace opening of the furnace body 1 respectively;

[0095] Step 2: Insert the cleaning tube 8 into the straight hole of the front furnace plug 3 so that the other end of the cleaning tube 8 extends into the detection chamber of the furnace body 1 until the end of the cleaning tube 8 is inserted into the round hole of the rear furnace plug 2.

[0096] Step 3: Insert the three protective tubes 6 into the multiple through holes 203 of the rear furnace plug 2 respectively and push the protective tubes 6 so that the protective tubes 6 extend into the detection chamber. At the same time, calculate the insertion depth of the protective tubes 6 based on the number of scale holes 601 exposed on the outside of the protective tubes 6 to ensure that the protective tubes 6 are inserted into the predetermined position. Then, fully insert the measuring end of the temperature control thermocouple 4 into the protective tubes 6.

[0097] Step 4: Connect multiple temperature-controlled thermocouples in parallel;

[0098] Step 5: Insert the precious metal thermocouple cluster to be tested into the front furnace plug 3 and push the precious metal thermocouple cluster to be tested so that it extends into the cleaning tube 8, and then confirm its insertion depth.

[0099] Step 6: After confirming that the tested precious metal thermocouple cluster is correctly inserted, use the matching small furnace plug 9 to seal the round hole in the rear furnace plug 2, and then use heat insulation fiber to seal the gaps at the front and rear furnace openings.

[0100] The calibration method for the base metal thermocouple under test includes the following steps:

[0101] Step 1: Take a small amount of heat-insulating glass fiber with a thickness of about 5mm, wrap it evenly around the conical surface of the rear furnace plug 2, and then slowly insert the rear furnace plug 2 into the rear furnace opening of the furnace body 1.

[0102] Step 2: Insert the three protective tubes 6 into the multiple through holes 203 of the rear furnace plug 2 respectively and push the protective tubes 6 so that the protective tubes 6 extend into the detection chamber. At the same time, calculate the insertion depth of the protective tubes 6 based on the number of scale holes 601 exposed on the outside of the protective tubes 6 to ensure that the protective tubes 6 are inserted into the predetermined position. Then, fully insert the measuring end of the temperature control thermocouple 4 into the protective tubes 6.

[0103] Step 3: Insert the temperature equalization block 5 into the detection chamber from the front furnace opening and move it to the vicinity of the center position of the detection chamber. Then use a tool to rotate the temperature equalization block 5 so that the notch 501 on the temperature equalization block 5 is aligned with the protective tube 6. Then continue to push the temperature equalization block 5 so that the protective tube 6 is inserted into the notch 501. Then wrap the front furnace plug 3 with heat insulation fiber and insert the front furnace plug 3 into the front furnace opening of the furnace body 1.

[0104] Step 4: Connect the three temperature-controlled thermocouples in parallel;

[0105] Step 5: Insert the bundled bare metal thermocouple cluster into the front furnace opening and push it until it is inserted into the inner cavity 504 of the temperature equalization block 5. Then use heat insulation fiber to seal the gap between the bare metal thermocouple cluster and the front furnace opening.

[0106] It should be noted that if the number of base metal thermocouples in the base metal thermocouple cluster being inspected is small, resulting in the diameter of the base metal thermocouple cluster being inspected being smaller than the diameter of the straight hole in the front furnace plug 3, then the bundled base metal thermocouple cluster being inspected can be inserted into the straight hole in the front furnace plug 3.

[0107] Step 6: After confirming that the base metal thermocouple cluster being inspected is correctly inserted, use the matching small furnace plug 9 to seal the round hole inside the rear furnace plug 2, and then use heat insulation fiber to seal the gaps at the front and rear furnace openings.

[0108] In the description of this invention, it should be noted that the terms "upper" and "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0109] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0110] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermocouple calibration furnace, characterized in that, It includes a furnace body (1), a front furnace plug (3), a rear furnace plug (2), and at least one temperature control thermocouple (4); The furnace body (1) is provided with a detection chamber that runs through the furnace body (1), one end of the detection chamber is the front furnace opening and the other end is the rear furnace opening; The rear furnace plug (2) has through holes (203) that correspond one-to-one with the temperature control thermocouple (4) along its axial direction, and the front furnace plug (3) has at least one straight hole for the thermocouple under test to pass through along its axial direction. The thermocouple calibration furnace also includes protective tubes (6) that correspond one-to-one with the through holes (203). In each set of corresponding protective tubes (6), through holes (203), and temperature-controlled thermocouples (4), the protective tube (6) passes through the through hole (203) and extends to the middle position of the detection cavity. The temperature-controlled thermocouple (4) is inserted into the protective tube (6) so that the measuring end of the temperature-controlled thermocouple (4) extends into the middle position of the detection cavity. When the rear furnace plug (2) and the front furnace plug (3) are respectively inserted into the rear furnace opening and the front furnace opening, the axis of the through hole (203) and the axis of the straight hole are not collinear. The rear furnace plug (2) is provided with a round hole, and the axis of the round hole is collinear with the axis of the rear furnace plug (2), so that the temperature control thermocouple (4) inserted into the through hole (203) and the thermocouple under test inserted into the straight hole are misaligned. The axis of the rear furnace plug (2) is not collinear with the axis of the through hole (203) on the rear furnace plug (2), and the straight hole on the front furnace plug (3) is collinear with the axis of the front furnace plug (3). Multiple through holes (203) are provided, and the multiple through holes (203) are evenly distributed around the axis of the rear furnace plug (2). Multiple temperature control thermocouples (4) are provided, and the temperature control thermocouples (4) correspond one-to-one with the through holes (203). The multiple temperature control thermocouples (4) are connected in parallel with each other. The length of the protective tube (6) is at least half the depth of the detection cavity, such that when the first end of the protective tube (6) extends into the middle position of the detection cavity, the second end of the protective tube (6) is exposed outside the thermocouple calibration furnace. The protective tube (6) has multiple scale holes (601) at one end near the rear furnace plug (2), and the multiple scale holes (601) are evenly arranged along the axial direction of the protective tube (6). The thermocouple calibration furnace includes a temperature equalization block (5), the temperature equalization block (5) has an inner cavity (504) inside, the temperature equalization block (5) has multiple notches (501) on the end face of the temperature equalization block (5) facing the rear furnace plug (2) for inserting the protective tube (6), the multiple notches (501) are evenly arranged around the axis of the temperature equalization block (5), the temperature equalization block (5) has a central hole (505) on the end face of the temperature equalization block (5) facing the front furnace plug (3) for the thermocouple under test to pass through, and multiple holes (503) are evenly arranged around its axis on the side of the temperature equalization block (5). The thermocouple calibration furnace includes a cleaning tube (8), which is fitted inside the testing chamber. One end of the cleaning tube (8) is inserted into the straight hole in the front furnace plug (3), and the other end is inserted into the round hole in the rear furnace plug (2).

2. A calibration method based on the thermocouple calibration furnace according to claim 1, characterized in that, The verification method includes the following steps: S1: Wrap the heat insulation fiber around the rear furnace plug (2), and then insert the rear furnace plug (2) into the rear furnace opening of the furnace body (1); S2: Insert each protective tube (6) into the corresponding through hole (203) on the rear furnace plug (2) and push the protective tube (6) so that the protective tube (6) extends into the detection chamber, and ensure that the protective tube (6) is inserted into the predetermined position. Then, fully insert the measuring end of the temperature control thermocouple (4) into the protective tube (6). S3: Wrap the front furnace plug (3) with heat insulation fiber, and then insert the front furnace plug (3) into the front furnace opening of the furnace body (1); S4: Insert the thermocouple cluster to be tested into the straight hole of the front furnace plug (3) and push the thermocouple cluster to be tested to ensure that the thermocouple cluster to be tested extends into the middle position of the detection cavity, so that the temperature control thermocouple (4) and the thermocouple cluster to be tested are staggered, and then confirm the insertion depth of the thermocouple to be tested. S5: Use heat-insulating fibers to seal the gaps at the front and rear furnace openings.

3. The testing method according to claim 2, characterized in that, When this calibration method is used to test the noble metal thermocouple under test, the calibration method further includes: Between S3 and S4, the cleaning tube (8) is inserted through the straight hole of the front furnace plug (3) so that the other end of the cleaning tube (8) extends into the detection chamber of the furnace body (1) and forms an assembly relationship with the rear furnace plug (2); When this calibration method is used to test the base metal thermocouple under test, the calibration method further includes: Insert the temperature equalization block (5) into the detection chamber from the front furnace opening between S2 and S3, move it to the vicinity of the center position of the detection chamber, and then use a tool to rotate the temperature equalization block (5) so that the notch (501) on the temperature equalization block (5) is aligned with the protective tube (6), and then continue to push the temperature equalization block (5) so that the protective tube (6) is inserted into the notch (501).

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