Tool for calibrating precious metal thermocouple and calibrating furnace thereof

Abstract

The utility model discloses a tool for calibrating a precious metal thermocouple and a calibrating furnace thereof, and relates to the technical field of precious metal thermocouple calibration. The tool for calibrating the precious metal thermocouple comprises an insulating tube kit and a central insulating tube, a through insulating tube channel is arranged in the insulating tube kit, one end of the insulating tube kit forms a measuring end, a plurality of reference ends are formed on the outer ring surface, the measuring end is provided with a first thermo wire channel, each reference end is provided with a second thermo wire channel, and the first thermo wire channel is communicated with the central insulating tube. The outer ring surface between the measuring end and the reference end and between every two adjacent reference ends in the insulating tube suite is provided with thermo wire grooves, each group of corresponding thermo wire grooves, first thermo wire channels and second thermo wire channels are communicated with each other, and the central insulating tube penetrates into the insulating tube channels. A positive standard couple electrode wire and a negative standard couple electrode wire which are communicated with each other are arranged in the central insulating tube, and the two positive standard couple electrode wires and the two negative standard couple electrode wires form a standard couple. The tool for detecting the precious metal thermocouple facilitates penetration and leading-out of electrode wires of the precious metal thermocouples with different lengths.

Description

Technical Field

[0001] This utility model relates to the field of precious metal thermocouple calibration technology, specifically a tooling for calibrating precious metal thermocouples and its calibration furnace. Background Technology

[0002] Currently, in thermocouple calibration, the standard thermocouple and the thermocouple under test are typically bundled together with platinum wire, with the measuring ends of both the standard and under test thermocouples on the same end face. To ensure that the electrodes outside the measuring ends do not come into contact with each other, before bundling, each 0.5mm diameter precious metal thermocouple electrode wire should be manually inserted into a corundum insulating tube with an aperture ≤1mm, an outer diameter 5mm, and a length ≥450mm. Then, the thermocouple wire bundle at the measuring end is bundled with platinum wire, and the bundled thermocouple is placed coaxially in the calibration furnace. The measuring end is placed at the physical heating center of the thermocouple calibration furnace. Simultaneously, the bundled thermocouple under test and the reference end of the standard thermocouple are connected to a freezing point thermostat, and then led out through homogeneous copper wire and connected to a digital voltmeter or thermocouple calibration system to complete the calibration system connection operation.

[0003] The existing technical solutions described above have the following technical defects: First, due to the softness of the precious metal thermocouple electrode wire and the roughness of the inner wall of the corundum insulating tube, it is difficult to manually insert the thermocouple electrode wire into a corundum insulating tube with a length ≥450mm. Second, in actual calibration work, the length of the thermocouples being calibrated is not uniform. Furthermore, to improve calibration efficiency, it may be necessary to use a short-type thermocouple calibration furnace to simultaneously calibrate both ordinary-length and short-type thermocouples. This requires bundling ordinary-length and short-type corundum insulating tubes together, which can be inconvenient due to the different binding constraints. Third, due to the special nature of precious metal thermocouple calibration, platinum wire must be used for binding the corundum insulating tubes entering the furnace, binding the measuring ends of the precious metal thermocouples, and binding the insulating tubes within the furnace. Therefore, there will be costs associated with the consumption of platinum wire in actual work. Utility Model Content

[0004] The purpose of this invention is to provide a tooling and calibration furnace for calibrating precious metal thermocouples, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a tooling for calibrating precious metal thermocouples, comprising an insulating tube assembly and a central insulating tube, wherein the insulating tube assembly has an insulating tube channel extending through it along a first direction, and one end of the insulating tube assembly forms a measuring end along the first direction. Multiple reference ends distributed along the first direction are formed on the outer ring surface of the insulating tube assembly. The measuring end has several first thermocouple wire channels, and each reference end has a second thermocouple wire channel corresponding to one of the first thermocouple wire channels. The outer ring surface of the insulating tube assembly between the measuring end and its adjacent reference end, and between every two adjacent reference ends, has thermocouple wire grooves extending along the first direction and corresponding to the first reference end. The first thermocouple wire channels are one-to-one, and the first direction is parallel to the axial direction of the insulating tube assembly. Each set of corresponding thermocouple wire grooves, first thermocouple wire channels, and second thermocouple wire channels are interconnected. The width of the groove in the circumferential direction of the thermocouple wire around the insulating tube assembly is greater than the diameter of the electrode wire of the precious metal thermocouple. The thermocouple wire groove forms a limiting mechanism to restrict the electrode wire from coming out. The central insulating tube has two positive and negative standard thermocouple electrode wires that pass through it along its own axial direction. The central insulating tube passes into the insulating tube channel, and the two positive and negative standard thermocouple electrode wires extend out of the measuring end of the insulating tube assembly and are connected at the measuring end to form a standard thermocouple. At the same time, the connection part of the positive and negative standard thermocouple electrode wires forms the standard thermocouple measuring end.

[0006] Based on the above technical features, when using the precious metal thermocouple calibration fixture of this utility model to calibrate the thermocouple to be calibrated, the two positive and negative electrode wires of the thermocouple to be calibrated are inserted from the two adjacent first thermocouple wire channels at the measuring end toward the reference end. When the electrode wires emerge into the thermocouple wire groove, the electrode wires are carefully pulled toward the reference end according to the length of the electrode wires of the thermocouple to be calibrated, until the measuring end of the thermocouple to be calibrated reaches the designated installation position at the measuring end. Then, the reference ends of the two positive and negative electrode wires are led out from the end of the insulating tube kit or from the thermocouple wire groove. The electrode wires of multiple thermocouples to be calibrated are inserted and installed one by one according to the above steps. Finally, after connecting the reference ends of the thermocouple to be calibrated and the standard thermocouple to the freezing point thermostat, the reference ends are led out through homogeneous copper wires and connected to a digital voltmeter or thermocouple calibration system to complete the calibration system connection operation. In this embodiment of the invention, the apertures of the first and second thermocouple channels are more than three times the diameter of the electrode wire, and the groove width of the thermocouple groove along the circumferential direction of the insulating tube assembly is more than four times the diameter of the electrode wire. Furthermore, the shorter aperture design of the first and second thermocouple channels, along with the open groove design, facilitates the insertion and installation of the electrode wire within the tooling for calibrating precious metal thermocouples. Additionally, depending on the length of the precious metal thermocouple, the reference end of the electrode wire can be led out from the end of the insulating tube assembly or from the thermocouple groove between adjacent reference ends. Only the measuring end of the thermocouple to be calibrated and the measuring end of the standard thermocouple need to be bound together using platinum wire. This reduces the costs associated with binding the corundum insulating tubes entering the calibration furnace with platinum wire, as well as the inconvenience caused by inconsistent thermocouple lengths.

[0007] In a preferred embodiment of this technical solution, the limiting mechanism includes a plurality of limiting blocks formed at the opening of the thermocouple wire groove and distributed along the first direction; each pair of adjacent limiting blocks are staggered and installed on both sides of the groove opening, each limiting block extending along the circumferential direction of the insulating tube assembly, and the distance between the end of each limiting block away from the edge of the groove and the opposite edge of the groove is greater than the diameter of the electrode wire of the precious metal thermocouple. More preferably, in this embodiment of the invention, the ratio between the distance between the end of each limiting block away from the edge of the groove and the opposite edge of the groove and the diameter of the electrode wire of the precious metal thermocouple is 1.5:1 to 2.5:1.

[0008] Based on the above technical features, the distance between the end of the limiting block away from the edge of the groove and the opposite edge of the groove is greater than the diameter of the electrode wire of the precious metal thermocouple, which facilitates the insertion of the electrode wire into the thermocouple groove. At the same time, the combination of the thermocouple groove and the limiting block forms a limiting mechanism, which can effectively prevent the electrode wire from coming out of the thermocouple groove when the precious metal thermocouple is being tested.

[0009] In this preferred embodiment, along the first direction, the distance between the centerline of the first hybrid wire channel and the axis of the insulating tube assembly gradually decreases, and the angle between the extended line of the centerline of the first hybrid wire channel and the axis of the insulating tube assembly ranges from 20° to 30°.

[0010] Based on the above technical features, the first thermocouple wire channel is designed with a small angle of 20° to 30° at the measuring end to ensure that the thermocouple measuring end (specifically the measuring end of the thermocouple being calibrated or the measuring end of the standard thermocouple) can better converge towards the center, thereby reducing the space occupied by the measuring end, thus obtaining a relatively more consistent temperature field and ultimately improving the accuracy of the measurement.

[0011] In this preferred embodiment, a guide groove extending along the first direction is formed on the inner wall of the insulating tube channel, and a stop block is installed on the outer ring surface of the central insulating tube near the standard couple measuring end; when the central insulating tube is in the first state, the central insulating tube can slide guidedly within the guide groove with the stop block; when the central insulating tube is in the second state, the central insulating tube can form a limiting fit with the stop block that slides out of the guide groove and the insulating tube assembly.

[0012] Based on the above technical features, a guide groove is opened on the inner wall of the insulating tube channel for guiding and positioning the central insulating tube when it extends into the insulating tube channel. After the stop block slides out of the guide groove, the central insulating tube is rotated to achieve the limiting combination of the central insulating tube and the insulating tube assembly, thereby achieving a snap-fit ​​and preventing the central insulating tube from coming out along the insulating tube channel.

[0013] In a preferred embodiment of this technical solution, the tooling for calibrating precious metal thermocouples further includes a heat-spreading cover. The bottom of the heat-spreading cover has a groove extending from the inner wall to the outer wall. An annular groove is provided on the inner wall of the heat-spreading cover, concentrically positioned with the heat-spreading cover. A limiting ear is provided on the outer ring surface of the measuring end, corresponding one-to-one with the groove. The width of the limiting ear is less than the width of the groove, and the height of the limiting ear is less than the width of the annular groove.

[0014] Based on the above technical features, a heat-equalizing cover is set at the measuring end of the insulating tube kit, which can store heat and provide a relatively stable and uniform temperature field for the measuring end. This helps to optimize the uniform temperature field at the measuring end, improve the calibration quality, and at the same time, reduce the amount of platinum wire used for binding the measuring end and the amount of binding work for workers.

[0015] In this preferred embodiment, the insulating tube assembly, the central insulating tube, and the heat-spreading cover are all made of corundum material.

[0016] In this preferred embodiment, a support boss is provided on the outer ring surface of each reference end, and the support boss can be adapted to the detection cavity inside the calibration furnace.

[0017] Based on the above technical features, multiple sets of support bosses are provided on the outer ring surface of the insulating tube kit, which can prevent the insulating tube kit from slipping and rolling when placed on the workbench surface, and can also provide installation support for the insulating tube kit when it is inserted into the detection cavity.

[0018] A precious metal thermocouple calibration furnace includes the aforementioned tooling for calibrating precious metal thermocouples, as well as a calibration furnace body and a thermocouple to be calibrated installed within the tooling. The calibration furnace body has a detection chamber that penetrates the furnace body. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a tooling for calibrating precious metal thermocouples in an embodiment of this utility model (excluding the heat spreader cover);

[0020] Figure 2 As an embodiment of this utility model Figure 1 AA cross-section view;

[0021] Figure 3 As an embodiment of this utility model Figure 1 BB cross-section;

[0022] Figure 4 As an embodiment of this utility model Figure 1 DD cross-section;

[0023] Figure 5 As an embodiment of this utility model Figure 1 EE cross-section;

[0024] Figure 6 This is a schematic diagram of the central insulating tube structure in an embodiment of this utility model;

[0025] Figure 7 As an embodiment of this utility model Figure 6 FF sectional view;

[0026] Figure 8 As an embodiment of this utility model Figure 6 CC section view;

[0027] Figure 9 This is a schematic diagram of the insulating tube assembly in an embodiment of this utility model;

[0028] Figure 10 As an embodiment of this utility model Figure 9 GG cross-sectional view;

[0029] Figure 11 This is a schematic diagram of the heat spreader cover in an embodiment of the present invention;

[0030] Figure 12This is a bottom view of the heat-spreading cover in an embodiment of this utility model;

[0031] Figure 13 As an embodiment of this utility model Figure 12 HH rotated sectional view;

[0032] Figure 14 This is a bottom view of the tooling (including a heat-spreading cover) for calibrating precious metal thermocouples in this embodiment of the present invention when it is inserted into a short precious metal thermocouple calibration furnace (the length of the testing chamber is 300mm to 340mm).

[0033] Figure 15 As an embodiment of this utility model Figure 14 JJ sectional view;

[0034] Figure 16 This is a top view of the precious metal thermocouple calibration fixture (including a heat-spreading cover) inserted into the precious metal thermocouple calibration furnace (test chamber length is 600mm to 680mm) in this embodiment of the present invention.

[0035] Figure 17 As an embodiment of this utility model Figure 16 KK sectional view;

[0036] Figure 18 This is a top view of the precious metal thermocouple calibration tool (including a cleaning tube) inserted into the precious metal thermocouple calibration furnace in an embodiment of this utility model.

[0037] Figure 19 As an embodiment of this utility model Figure 18 NN cross-sectional view.

[0038] In the diagram: 1. Insulating tube assembly; 11. Insulating tube channel; 11A. Guide groove; 12. Measuring end; 12A. First thermocouple wire channel; 12B. Limiting ear; 13. Reference end; 13A. Second thermocouple wire channel; 13B. Support boss; 14. Thermocouple wire groove; 15. Limiting block; 16. Thermocouple under test; 16A. Measuring end of the thermocouple under test; 2. Center insulating tube; 21. Standard thermocouple; 21A. Measuring end of the standard thermocouple; 22. Stop block; 3. Heat spreader cover; 31. Groove; 32. Annular groove; 4. Calibration furnace; 41. Testing chamber; 42. Front of calibration furnace; 43. Back of calibration furnace; 44. Calibration furnace body; 45. Tube wall support; 5. Cleaning tube. Detailed Implementation

[0039] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0040] It should be noted that in the description of this utility model, the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model.

[0041] Furthermore, it should be understood that, for ease of description, the dimensions of the various components shown in the accompanying drawings are not drawn to actual scale.

[0042] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined or described in one figure, it will not need to be discussed or described in detail in the description of the subsequent figures.

[0043] Before understanding this utility model, it is important to understand that a thermocouple typically consists of electrode wires made of two different materials. One end of each electrode wire is fixed together by welding or fusion to form the thermocouple measuring end (i.e., the hot junction), and the other end is the thermocouple reference end (i.e., the cold junction). The measuring end is used to sense temperature changes and generate a thermoelectric potential, while the reference end serves as a temperature reference. When calibrating a thermocouple in a calibration furnace, the measuring end is typically inserted into the testing chamber of the furnace to a depth of 1 / 2. The reference end is connected to a freezing point thermostat and then led out through homogeneous copper wires to a digital voltmeter or thermocouple calibration system. Meanwhile, during thermocouple calibration, the total number of standard thermocouples and thermocouples under test should generally not exceed five, that is, ensuring that there is one standard thermocouple and a total of no more than four thermocouples under test, in order to ensure the accuracy of the measurement results. Under special circumstances (for example, when the calibration furnace capacity is improved and the temperature field stability required by the relevant regulations can be guaranteed), the total number of standard thermocouples and thermocouples under test can exceed five during thermocouple calibration.

[0044] like Figures 1 to 13 As shown, this utility model provides a technical solution: a tooling for calibrating precious metal thermocouples, wherein the tooling for calibrating precious metal thermocouples includes an insulating tube assembly 1 and a central insulating tube 2.

[0045] The insulating tube assembly 1 has an insulating tube channel 11 that runs through it along a first direction. Along the first direction, one end of the insulating tube assembly 1 forms a measuring end 12. Multiple reference ends 13 distributed along the first direction are formed on the outer ring surface of the insulating tube assembly 1. Several first coupler channels 12A are formed on the measuring end 12. Each reference end 13 has a second coupler channel 13A that corresponds one-to-one with the first coupler channel 12A. Coupler grooves 14 are formed on the outer ring surface of the insulating tube assembly 1 between the measuring end 12 and its adjacent reference end 13 and between each pair of adjacent reference ends 13. The coupler grooves 14 extend along the first direction and correspond one-to-one with the first coupler channels 12A. The first direction is parallel to the axial direction of the insulating tube assembly 1. Each set of corresponding thermocouple grooves 14, first thermocouple channel 12A, and second thermocouple channel 13A are interconnected. The width of the groove in the circumferential direction of the thermocouple groove 14 around the insulating tube assembly 1 is greater than the diameter of the electrode wire of the precious metal thermocouple. The thermocouple groove 14 is formed with a limiting mechanism to restrict the electrode wire from coming out.

[0046] The central insulating tube 2 has two positive and negative standard electrode wires running through it along its own axis. The central insulating tube 2 passes into the insulating tube channel 11, and the two positive and negative standard electrode wires extend out of the measuring end 12 of the insulating tube kit 1 and are connected and combined at the measuring end 12 to form a standard couple 21. At the same time, the connection part of the positive and negative standard electrode wires forms the standard couple measuring end 21A. The standard couple 21 is a precious metal thermocouple. In order to avoid the base metal thermocouple from contaminating the precious metal standard couple 21 under high temperature conditions, the thermocouples 16 being calibrated in this utility model are all precious metal thermocouples. Specifically, the precious metal thermocouple types can be S-type (platinum-rhodium 10-platinum), R-type (platinum-rhodium 13-platinum), and B-type (platinum-rhodium 30-platinum-rhodium 6), which are suitable for high temperature environments and have high precision, good stability and oxidation resistance.

[0047] Specifically, such as Figures 1-5 , Figures 9-10 As shown in the embodiment of this utility model, twelve sets of corresponding and interconnected thermocouple grooves 14, first thermocouple channels 12A, and second thermocouple channels 13A are formed. Specifically, the measuring end 12 of the insulating tube assembly 1 has twelve evenly arranged first thermocouple channels 12A, and each reference end 13 has twelve evenly arranged second thermocouple channels 13A along a first direction. Between the measuring end 12 and its adjacent reference end 13, twelve thermocouple grooves 14 distributed along the circumference of the insulating tube assembly 1 are formed. Between two adjacent reference ends 13, twelve thermocouple grooves 14 distributed along the circumference of the insulating tube assembly 1 are also formed. In the embodiment of this utility model, up to six thermocouples 16 to be calibrated and one standard thermocouple 21 can be simultaneously placed into the calibration furnace 4 for calibration work.

[0048] The aperture of the first dipole wire channel 12A and the aperture of the second dipole wire channel 13A are not less than 1.5 mm. For example, the apertures of the first dipole wire channel 12A and the second dipole wire channel 13A can be selected as 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm... The apertures of both the first dipole wire channel 12A and the second dipole wire channel 13A are at least three times the diameter of the 0.5 mm electrode wire. Simultaneously, the groove width of the dipole wire groove 14 along the circumference of the insulating tube is not less than 2 mm and not more than 3 mm. For example, it can be selected as 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm... 2.9 mm. The groove opening width is [missing information - likely a value] times the diameter of the 0.5 mm electrode wire. The electrode wires are more than four times longer, which facilitates the insertion and installation of the electrode wires into the tooling for calibrating precious metal thermocouples. Furthermore, this invention allows the reference end of the electrode wire to be led out from the end of the insulating tube assembly 1 or from the wire groove 14 between adjacent reference ends, depending on the length of the precious metal thermocouple. Therefore, the tooling for calibrating precious metal thermocouples in this invention can accommodate thermocouples 16 of different lengths. Depending on the length of the thermocouple 16, the reference end of the thermocouple 16 can be passed out from an appropriate position, improving the complexity of organizing the reference end leads of the thermocouple 16. This solves the problems of the cost of using platinum wire for binding in the prior art, and the inconvenience of binding caused by the inconsistent lengths of the thermocouples 16.

[0049] Furthermore, chamfers are designed at the openings of the first electrode wire channel 12A and the second electrode wire channel 13A to facilitate the insertion and exit of the electrode wire. At the same time, the chamfered surface can also reduce the frictional resistance during electrode wire assembly, and prevent the electrode wire from being worn or scratched, thus affecting the measurement results.

[0050] like Figure 1 , Figure 3 , Figure 4 , Figure 10As shown, the limiting mechanism includes a plurality of limiting blocks 15 formed at the opening of the thermocouple wire groove 14 and distributed along a first direction. Each pair of adjacent limiting blocks 15 are staggered and installed on both sides of the groove opening. Each limiting block 15 extends along the circumferential direction of the insulating tube assembly 1, and the ratio between the distance between the end of each limiting block 15 away from the edge of the groove and the opposite edge of the groove opening is 1.5:1 to 2.5:1 with respect to the diameter of the electrode wire of the precious metal thermocouple. For example, in the national standard, the diameter of the electrode wire is 0.5 mm. The distance between the end of each limiting block 15 away from the edge of the groove and the opposite edge of the groove opening can be selected as 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm...1.25 mm, or any value between the above two values. Preferably, in the embodiment shown in this utility model, each wire groove 14 is equipped with two staggered limiting blocks 15. The wire groove 14 and the two limiting blocks 15 together form a limiting mechanism. The extension length of the two limiting blocks 15 is 1.5mm, which not only ensures that a 0.5mm electrode wire can be inserted under open conditions, but also ensures that the two staggered limiting blocks 15 can overlap on the projection plane along the first direction (see attached figure for details). Figure 4 This effectively prevents the electrode wire from coming out of the coupler groove 14.

[0051] Along the first direction, the distance between the centerline of the first thermocouple channel 12A and the axis of the insulating tube assembly 1 gradually decreases, and the angle between the extended line of the centerline of the first thermocouple channel 12A and the axis of the insulating tube assembly 1 ranges from 20° to 30°. The first thermocouple channel 12A features a small-angle guiding design at the measuring end 12 to guide the electrode wire, ensuring that the measuring end of the noble metal thermocouple can better converge towards the center, thereby reducing the space occupied by the measuring end, obtaining a relatively more uniform temperature field, and ultimately improving the accuracy of the measurement.

[0052] The inner wall of the insulating tube channel 11 is provided with a guide groove 11A extending in a first direction. A stop block 22 is installed on the outer ring surface of the central insulating tube 2 near the standard couple measuring end 21A. The central insulating tube 2 can slide within the guide groove 11A with the stop block 22. When the stop block 22 slides out of the guide groove 11A, rotating the central insulating tube 2 can achieve a limiting combination between the central insulating tube 2 and the insulating tube assembly 1, realizing a snap-fit ​​and preventing the central insulating tube 2 from coming off along the insulating tube channel 11. In this utility model, the outer diameter of the central insulating tube 2 is 5mm, and the insulating tube assembly 1 has an insulating tube channel 11 with a guide groove 11A along its own axial direction. The central insulating tube 2 can form an assembly relationship with the circular hollow insulating tube channel 11.

[0053] Specifically, such as Figures 1-5 , Figure 7 , Figure 9As shown, the inner wall of the insulating tube channel 11 has two opposing guide grooves 11A, the cross-sectional shape of which is rectangular. Two stop blocks 22 are installed on the outer ring surface of the central insulating tube 2 near the standard thermocouple measuring end 21A. The stop blocks 22 are adapted to the cross-sectional shape of the guide grooves 11A. In this utility model, the guide grooves 11A are provided on the inner wall of the insulating tube channel 11 for guiding and positioning the central insulating tube 2 when it extends into the insulating tube channel 11. When the stop blocks 22 slide out of the guide grooves 11a, rotating the central insulating tube 2 can achieve the limiting combination of the central insulating tube 2 and the insulating tube assembly 1, which are mutually locked to prevent the central insulating tube 2 from falling out along the insulating tube channel 11 when calibrating the precious metal thermocouple.

[0054] like Figures 11-13 , Figure 15 , Figure 17 As shown, the fixture for calibrating precious metal thermocouples also includes a heat-spreading cover 3. The bottom of the heat-spreading cover 3 has a groove 31 extending from the inner wall to the outer wall. An annular groove 32 is provided on the inner wall of the heat-spreading cover 3, concentrically positioned with the heat-spreading cover 3. A limiting ear 12B is provided on the outer ring surface of the measuring end 12. The limiting ear 12B corresponds one-to-one with the groove 31. The width of the limiting ear 12B is less than the width of the groove 31, and the height of the limiting ear 12B is less than the width of the annular groove 32, so that the limiting ear 12B can successively extend into the groove 31 and the annular groove 32, forming a limiting fit between the heat-spreading cover 3 and the insulating tube assembly 1, achieving a snap-fit ​​fixation. In this invention, a heat-spreading cover 3 is provided at the measuring end 12 of the insulating tube assembly 1. This cover can store heat and provide a relatively stable and uniform temperature field for the measuring end 12, thereby improving the calibration quality. At the same time, tests have shown that under the original calibration furnace conditions, with the addition of the heat-spreading cover 3, the fluctuation range during stabilization can be reduced from the original ±0.0020mV to ±0.0012mV without binding the measuring ends of the thermocouples under calibration and the standard couples. Therefore, in addition to helping to optimize the uniform temperature field of the measuring end 12, the heat-spreading cover 3 can also reduce the amount of platinum wire used to bind the measuring ends of the thermocouples under calibration and the workload of workers.

[0055] In this utility model, the configuration and structure of the existing precious metal thermocouple calibration furnace are not changed. The design of the first thermocouple wire channel 12A at the measuring end 12 of the insulating tube kit 1 and the design of the heat spreader cover 3 can improve the compatibility and adaptability of the tooling for precious metal thermocouple calibration with the existing precious metal thermocouple calibration furnace, and can realize the direct insertion of bare tubes into the detection chamber 41 of the existing thermocouple calibration furnace.

[0056] Furthermore, the insulating tube assembly 1, the central insulating tube 2, and the heat-spreading cover 3 are all made of corundum material. In other embodiments, materials with higher density and better temperature resistance can be used instead of the aforementioned corundum material.

[0057] Each reference end 13 has a support boss 13B on its outer ring surface, which can be adapted to the detection cavity 41 inside the calibration furnace 4. This utility model provides multiple sets of support bosses 13B on the outer ring surface of the insulating tube assembly 1, with an outer diameter of 20mm. This can prevent the insulating tube assembly 1 from slipping and rolling when placed on the workbench surface, and can also provide installation support for the insulating tube assembly 1 when it is inserted into the detection cavity 41.

[0058] like Figure 14 and Figure 19 As shown, a precious metal thermocouple calibration furnace includes a calibration furnace body 44, a tooling for calibrating precious metal thermocouples, and a thermocouple 16 to be calibrated installed in the tooling. The calibration furnace body 44 is provided with a detection cavity 41 that penetrates the calibration furnace body 44.

[0059] Specifically, Figures 14-15 The diagram shows the calibration furnace body 44 when the length of the testing chamber 41 is 300mm to 340mm, and the fixture (including a heat-spreading cover) for calibrating precious metal thermocouples extending to half the depth of the testing chamber 41. It is suitable for calibrating short and standard-length precious metal thermocouples. Short precious metal thermocouples can be led out from the wire groove 14 between adjacent reference ends, while standard-length precious metal thermocouples can be led out from the wire groove 14 between adjacent reference ends, or from the end of the insulating tube assembly 1. A tube wall support 45 is placed inside the calibration furnace body 44, abutting against the bottom of the insulating tube assembly 1, and is used to support the fixture for calibrating precious metal thermocouples during the calibration of the thermocouple 16.

[0060] Figures 16-17 The diagram shows the calibration furnace body 44 when the length of the testing chamber 41 is 600mm to 680mm, and the fixture (including a heat-spreading cover) for calibrating precious metal thermocouples extending to half the depth of the testing chamber 41. This fixture is suitable for calibration work involving only ordinary-length precious metal thermocouples, which can be led out from the end of the insulating tube assembly 1. A tube wall support 45 is placed inside the calibration furnace body 44, abutting against the bottom of the insulating tube assembly 1, and is used to support the fixture for calibrating precious metal thermocouples during the calibration of the thermocouple 16 being tested.

[0061] like Figures 18-19 As shown, a precious metal thermocouple calibration furnace also includes a cleaning tube 5, which is fitted inside the testing chamber 41. One end of the cleaning tube 5 is inserted into a straight hole in the front 42 of the calibration furnace, and the other end is inserted into a straight hole in the rear 43 of the calibration furnace.

[0062] See attached document Figure 1In this invention, the distance between the free end of the measuring end 12 and the adjacent reference end 13 is 120mm-130mm, the length of the reference end 13 is 30mm, and the distance between two adjacent reference ends 13 is 120mm-130mm. The specific values ​​can be designed according to the existing calibration furnace. Ultimately, a basic segment or segment combination can be adapted to the positioning of the central insulating tube 2 under the conditions of a short precious metal thermocouple calibration furnace with an insertion depth of 150mm-170mm and a precious metal thermocouple calibration furnace with an insertion depth of 300mm-340mm. The reference end of the electrode wire can be led out from the end of the insulating tube kit 1 or from the thermocouple wire groove 14 between adjacent reference ends.

[0063] The following are the steps for calibrating the thermocouple under test using a precious metal thermocouple calibration fixture with a heat spreader:

[0064] Step 1: Insert the two positive and negative electrode wires of the thermocouple 16 to be calibrated from the two adjacent first thermocouple wire channels 12A at the measuring end 12 toward the reference end 13;

[0065] Step 2: When the electrode wire extends into the thermocouple wire groove 14, carefully pull the electrode wire toward the reference end 13 according to the length of the electrode wire of the thermocouple 16 being calibrated, until the measuring end 16A of the thermocouple being calibrated reaches the designated installation position of the measuring end 12; during this process, depending on the length of different precious metal thermocouples, the reference end of the electrode wire can be led out from the end of the insulating tube kit 1, or from the thermocouple wire groove 14 between adjacent reference ends 13;

[0066] Step 3: Insert and install the electrode wires of the multiple thermocouples 16 to be calibrated one by one according to the above steps. After the insertion and installation are completed, carefully insert the electrode wires that have come out of the thermocouple wire groove 14 into the thermocouple wire groove 14 in the limiting block 15 one by one using tweezers. If necessary, heat insulation fiber can be inserted between the limiting block 15 and the thermocouple wire groove 14 to ensure that the electrode wires will not come out. Then straighten the electrode wires.

[0067] Step 4: Gently insert the heat-spreading cover 3 into the position of the limiting ear 12B, so that its groove 31 and the limiting ear 12B on the insulating tube kit 1 are in a matching relationship. Gently rotate the heat-spreading cover 3, with a rotation angle range of 25° to 35°, preferably 30°, until the limiting ear 12B extends into the annular groove 32, so that the heat-spreading cover 3 is "locked" on the measuring end 12.

[0068] Step 5: Insert the tooling for calibrating precious metal thermocouples, which has been completed in step 4, into the testing chamber 41 of the calibration furnace body 44 until the measuring end 16A of the thermocouple being calibrated and the measuring end 21A of the standard thermocouple are placed at 1 / 2 depth inside the testing chamber 41, thus completing the installation and positioning.

[0069] Step 6: After connecting the reference end of the thermocouple to be calibrated and the standard thermocouple to the freezing point thermostat, lead out the wires through homogeneous copper wires and connect them to a digital voltmeter or a precious metal thermocouple calibration system to complete the calibration system connection operation.

[0070] Step 7: Begin temperature rise and testing.

[0071] The procedure for calibrating the thermocouple under test using a precious metal thermocouple calibration fixture containing a clean tube is as follows:

[0072] Step 1: Insert the two positive and negative electrode wires of the thermocouple 16 to be calibrated from the two adjacent first thermocouple wire channels 12A at the measuring end 12 toward the reference end 13;

[0073] Step 2: When the electrode wire extends into the thermocouple wire groove 14, carefully pull the electrode wire toward the reference end 13 according to the length of the electrode wire of the thermocouple 16 being calibrated, until the measuring end 16A of the thermocouple being calibrated reaches the designated installation position of the measuring end 12; during this process, depending on the length of different precious metal thermocouples, the reference end of the electrode wire can be led out from the end of the insulating tube kit 1, or from the thermocouple wire groove 14 between adjacent reference ends 13;

[0074] Step 3: Insert and install the electrode wires of the multiple thermocouples 16 to be calibrated one by one according to the above steps. After the insertion and installation are completed, carefully insert the electrode wires that have come out of the thermocouple wire groove 14 into the thermocouple wire groove 14 in the limiting block 15 one by one using tweezers. If necessary, heat insulation fiber can be inserted between the limiting block 15 and the thermocouple wire groove 14 to ensure that the electrode wires will not come out. Then straighten the electrode wires.

[0075] Step 4: Bind the measuring end 16A of the thermocouple to be calibrated and the measuring end 21A of the standard thermocouple using platinum wire;

[0076] Step 5: Insert the precious metal thermocouple calibration tool from Step 3 into the test chamber 41 containing the cleaning tube 5 until the measuring end 16A of the thermocouple being calibrated and the measuring end 21A of the standard thermocouple are placed at 1 / 2 depth inside the test chamber 41 to complete the installation and positioning.

[0077] Step 6: After connecting the reference end of the thermocouple to be calibrated and the standard thermocouple to the freezing point thermostat, lead out the wires through homogeneous copper wires and connect them to a digital voltmeter or a precious metal thermocouple calibration system to complete the calibration system connection operation.

[0078] Step 7: Begin temperature rise and testing.

[0079] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A tooling for calibrating precious metal thermocouples, characterized in that, include: Insulating tube assembly (1) and center insulating tube (2), wherein, The insulating tube assembly (1) has an insulating tube channel (11) extending through it in a first direction. Along the first direction, one end of the insulating tube assembly (1) forms a measuring end (12). Multiple reference ends (13) distributed along the first direction are formed on the outer ring surface of the insulating tube assembly (1). Each measuring end (12) has several first coupler channels (12A), and each reference end (13) has a second coupler channel (13A) corresponding to one of the first coupler channels (12A). The insulating tube assembly (1) contains a measuring end (12) and its adjacent reference ends (13). A thermocouple groove (14) is provided on the outer ring surface between the two adjacent reference ends (13). The thermocouple groove (14) extends along the first direction and corresponds one-to-one with the first thermocouple channel (12A). The first direction is parallel to the axial direction of the insulating tube assembly (1). Each set of corresponding thermocouple grooves (14), the first thermocouple channel (12A), and the second thermocouple channel (13A) are interconnected. The groove width of the thermocouple groove (14) around the circumference of the insulating tube assembly (1) is greater than the diameter of the electrode wire of the noble metal thermocouple. The thermocouple groove (14) is formed with a limiting mechanism to restrict the electrode wire from coming out. The central insulating tube (2) has two positive and negative standard dipole wires running through it along its own axis. The central insulating tube (2) is inserted into the insulating tube channel (11), and the two positive and negative standard dipole wires extend out of the measuring end (12) of the insulating tube kit (1) and are connected at the measuring end (12) to form a standard dipole (21). At the same time, the connection part of the positive and negative standard dipole wires forms the standard dipole measuring end (21A).

2. The fixture for calibrating precious metal thermocouples according to claim 1, characterized in that, The limiting mechanism includes a plurality of limiting blocks (15) formed at the opening of the ferrule (14) and distributed along the first direction; Each pair of adjacent limiting blocks (15) are staggered and installed on both sides of the slot. Each limiting block (15) extends along the circumferential direction of the insulating tube assembly (1), and the distance between the end of each limiting block (15) away from the edge of the slot and the opposite edge of the slot is greater than the diameter of the electrode wire of the precious metal thermocouple.

3. The tooling for calibrating precious metal thermocouples according to claim 2, characterized in that, The ratio between the distance between the end of each limiting block (15) away from the edge of the slot and the opposite edge of the slot and the diameter of the electrode wire of the precious metal thermocouple is 1.5:1 to 2.5:

1.

4. The fixture for calibrating precious metal thermocouples according to claim 1, characterized in that, Along the first direction, the distance between the centerline of the first duct channel (12A) and the axis of the insulating tube assembly (1) becomes smaller and smaller, and the angle between the extension of the centerline of the first duct channel (12A) and the axis of the insulating tube assembly (1) ranges from 20° to 30°.

5. The fixture for calibrating precious metal thermocouples according to claim 1, characterized in that, A guide groove (11A) extending in the first direction is provided on the inner wall of the insulating tube channel (11), and a stop block (22) is installed on the outer ring surface of the central insulating tube (2) near the standard couple measuring end (21A); When the central insulating tube (2) is in the first state, the central insulating tube (2) can slide within the guide groove (11A) with the stop block (22); when the central insulating tube (2) is in the second state, the central insulating tube (2) can form a limiting fit with the stop block (22) that slides out of the guide groove (11A) and the insulating tube assembly (1).

6. The fixture for calibrating precious metal thermocouples according to claim 1, characterized in that, It also includes a heat spreader (3), wherein, The bottom of the heat spreader cover (3) is provided with a groove (31), which extends from the inner wall of the heat spreader cover (3) to the outer wall. An annular groove (32) is provided on the inner wall of the heat spreader cover (3), and the annular groove (32) is concentrically arranged with the heat spreader cover (3). A limiting ear (12B) is provided on the outer ring surface of the measuring end (12). The limiting ear (12B) corresponds one-to-one with the groove (31). The width of the limiting ear (12B) is smaller than the width of the groove (31), and the height of the limiting ear (12B) is smaller than the width of the annular groove (32).

7. The fixture for calibrating precious metal thermocouples according to claim 6, characterized in that, The insulating tube assembly (1), the central insulating tube (2), and the heat spreader (3) are all made of corundum material.

8. The fixture for calibrating precious metal thermocouples according to claim 1, characterized in that, Each of the reference ends (13) has a support boss (13B) on its outer ring surface, and the support boss (13B) can be adapted to the detection chamber (41) in the calibration furnace (4).

9. A precious metal thermocouple calibration furnace, characterized in that, The tooling for calibrating precious metal thermocouples, as described in any one of claims 1-8, further includes a calibration furnace body (44) and a precious metal thermocouple (16) to be calibrated installed in the tooling. The calibration furnace body (44) is provided with a detection chamber (41) that penetrates the calibration furnace body (44).

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