Armored thermocouple processing technology

Abstract

The present application relates to a processing technology for armored thermocouples, which includes the following steps: step 1, straightening and cutting; step 2, hot end processing, 2.1, hot end grinding, 2.2, sandblasting, 2.3, thermocouple wire welding processing, 2.4, hot end welding closure; step 3, cold end processing, 3.1, cold end cutting and breaking separation, 3.2, sandblasting, 3.3, preparation before sealing, baking in an oven to remove moisture, 3.4, sealing, taking out the metal sleeves from the oven, taking out 1 to 3 at a time, placing them on a baking tray and starting to apply glue, 3.5, drying, 3.6, baking, step 4, insulation testing to ensure insulation; step 5, polishing post-processing. The solution in this application provides a standardized process for deep processing of armored thermocouples, effectively improving production efficiency and making the moisture treatment in the process more standardized and reasonable, which can effectively ensure the product yield.

Description

Technical Field

[0001] The present application relates to the technical field of thermocouple processing, and in particular to a processing technology for armored thermocouples. Background Art

[0002] Armored thermocouples are a commonly used temperature measurement sensor, typically used in conjunction with temperature transmitters, regulators, and display instruments to form a temperature measurement and control system. They offer advantages such as high measurement accuracy, fast thermal response time, and durability.

[0003] The structure of an armored thermocouple generally consists of an outer metal sheath, an insulating material (usually magnesium oxide powder) filled within the metal sheath, and a thermocouple wire enclosed within the insulating material. One end of the armored thermocouple is the hot end, which directly contacts the environment being measured. The other end is the cold end, which connects to a subsequent connector and ultimately transmits the signal to the terminal.

[0004] The current mainstream processing technology can refer to the Chinese invention patent with authorization announcement number CN100530729C. The general solution is to first insert the thermocouple wire into the prefabricated insulation material hole, put a metal sleeve on the outside of the insulation material, and then draw and reduce the diameter and heat treat it to achieve the outer diameter that meets the product requirements.

[0005] In subsequent processing, the hot end of the thermocouple wire needs to be welded to form a loop, but a relatively standard processing technology has not been formed in the prior art. Summary of the Invention

[0006] In order to solve the above technical problems, the present application provides an armored thermocouple processing technology, which has the advantages of high production efficiency and easy control of product precision.

[0007] To achieve the above-mentioned purpose, the technical solution of the present invention is as follows:

[0008] A processing technology for an armored thermocouple comprises the following steps:

[0009] Step 1: Straighten and cut;

[0010] Step 2: Hot end treatment

[0011] 2.1. Grind the hot end to make the hot end surface smooth.

[0012] 2.2. Sandblasting, remove part of the magnesium oxide powder at the hot end of the metal sleeve, leaving a depth of L1,

[0013] 2.3. Thermocouple wire welding process,

[0014] 2.4. Close the hot end. Fill the space with magnesium oxide powder into the depth L1 and install the sealing piece to the hot end. The magnesium oxide powder needs to be dried on the heating plate in advance. The heating plate is set at 250℃.

[0015] 2.5. Welding of sealing piece and metal casing;

[0016] Step 3: Cold end treatment

[0017] 3.1. Cutting and breaking of the cold end,

[0018] 3.2. Sandblasting: Use a sandblasting machine to clean the inner and outer walls and the residue on the wires, and remove some magnesium oxide, leaving a space of depth L3 in the cold end.

[0019] 3.3. Preparation before sealing: bake in the oven to remove moisture.

[0020] 3.4. Sealing: Take out the metal sleeves from the oven, take out 1 to 3 at a time, place them on the baking tray and start applying glue.

[0021] 3.5. Dry, place vertically on a baking tray, and let it stand for more than 0.5 hours.

[0022] 3.6. Baking glue: the time and temperature requirements for baking glue are: first bake at 100℃ for 1 hour, then bake at 120℃ for 2 hours;

[0023] Step 4: Insulation test to ensure insulation;

[0024] Step 5: Polishing treatment: smooth the end of the thermocouple wire. When the length of the metal sleeve plus the exposed thermocouple wire is greater than 100mm, polish 50mm from the hot end. When the length of the metal sleeve plus the exposed thermocouple wire is less than 100mm, no polishing is required.

[0025] The implementation of the above technical solutions has formed a complete set of relatively standardized production and processing technologies, which has significantly improved the processing efficiency in the actual production process. Standardized moisture treatment is carried out in many places in the process to ensure the insulation of the magnesium oxide powder, thereby ensuring the final quality of the product and improving the yield rate.

[0026] As one of the optional embodiments of the present application, in steps 1 to 4, if either end of the metal sleeve needs to be exposed to the air for more than 3 minutes, a rubber sleeve must be installed on the end of the metal sleeve, and the two rubber sleeves on the same metal tube have a distinguishing structure for distinguishing the hot end and the cold end.

[0027] By implementing the above technical solution, the rubber sleeve effectively reduces the entry of external moisture into the magnesium oxide powder, thereby ensuring the insulation of the magnesium oxide powder, improving the molding quality of the product, and making it easier for operators to distinguish between the hot end and the cold end when picking up the rubber sleeve, thereby improving processing efficiency.

[0028] As one of the optional embodiments of the present application, L1 follows the following standard parameters: Φ6 metal sleeve-L1 depth 4mm, Φ4.5-L1 depth 3mm, Φ3-L1 depth 2mm, Φ2-L1 depth 1.5mm, and L3 is calculated according to the same rules as L1.

[0029] As one of the optional embodiments of the present application, after step 2.2, the depth L1 needs to be detected using a detection fixture, which includes a detection shaft that can be plugged into a matching metal sleeve configuration, a avoidance hole for the thermocouple wire to pass through is opened in the detection shaft, and a scale is provided on the outer wall of the detection shaft.

[0030] In implementing the above technical solution, the height and surface flatness of the magnesium oxide powder have a great influence on the insulation properties of the magnesium oxide powder, which in turn affects the quality of the operating product. The use of special fixtures combined with manual observation by the operator can more accurately determine the detection parameters.

[0031] As one of the optional embodiments of the present application, after step 1, the metal sleeve needs to be taken to a laser engraving machine for laser engraving.

[0032] As one of the optional embodiments of the present application, after step 2.3, it is necessary to take photos to record the solder joints. The solder joints in the photos must be clear to facilitate product traceability.

[0033] As one of the optional embodiments of the present application, between step 2.4 and step 2.5, the packaged metal sleeve needs to be placed in an oven at a temperature of 300°C-400°C for a time of ≥8 hours.

[0034] By implementing the above technical solution, the moisture content that may enter the magnesium oxide powder during the hot end treatment process is maintained below the standard as much as possible, thereby reducing the adverse effects of moisture.

[0035] As one of the optional embodiments of the present application, before welding the sealing piece, a 20 to 30 mm long area at the hot end is heated to red, and the sealing piece is welded using argon arc welding.

[0036] As one of the optional embodiments of the present application, after welding, the hot end diameter size needs to be checked to see if it can pass the gauge normally. If the tail end size has expanded, it needs to be ground down with a sanding machine so that it can pass the gauge smoothly.

[0037] As one of the optional embodiments of the present application, before performing step 3.4, the magnesium oxide powder needs to be subjected to an insulation test to determine whether there is moisture, including the following determination steps:

[0038] Step a: Lower the oven temperature from 400°C to 160°C and maintain the temperature for 1 hour, taking 1-3 pieces of the product out of the oven at a time.

[0039] Step b: Use an insulation resistance tester to perform an insulation test to ensure that the insulation is ≥2000MΩ / 500V. If the insulation does not meet the requirements, the metal sleeve needs to be placed in the oven for baking.

[0040] The above technical solution is implemented to ensure that the moisture content in the magnesium oxide powder is maintained within the required range, thereby ensuring product quality.

[0041] As one of the optional embodiments of the present application, the preparation of the glue in step 3.4 includes the following steps:

[0042] Step 1. Shake the curing agent for at least 3 minutes;

[0043] Step 2: Stir the epoxy resin glue for at least 3 minutes;

[0044] Step 3. After stirring evenly, mix the curing agent and epoxy resin glue in a ratio of 3:20, and stir for at least 3 minutes after mixing;

[0045] Among them, when using a new glue bottle for the first time after opening it, you need to use a stirring tool to thoroughly stir the sediment at the bottom of the bottle.

[0046] Step 4. Use a measuring container to hold the mixture of epoxy resin glue and curing agent.

[0047] As one of the optional embodiments of the present application, a secondary sealing of the cold end is required after step 3.6, which specifically includes the following steps:

[0048] Step m: After baking the glue, lower the oven temperature to 30-50°C to facilitate even glue flow during secondary sealing;

[0049] Step n, inject the epoxy glue into the syringe, and use a thin wire to expel the air from the needle end of the syringe;

[0050] Step o: Take out several metal sleeves from the oven each time, and use a syringe to evenly apply glue to cover the previous sealing position, ensuring that there are no bubbles;

[0051] Step P: Place the metal sleeve on a baking tray and put it into the oven, bake at 120 degrees for 2 hours.

[0052] By implementing the above technical solution, the sealing of the sealing position is ensured, thereby completely preventing external moisture from entering the magnesium oxide powder, thereby ensuring the molding quality of the product.

[0053] As one of the optional embodiments of the present application, the insulation detection process in step 4 includes:

[0054] After being placed in 100℃ boiling water for 10-15 minutes, the insulation test is carried out to ensure the insulation is 10000MΩ / 500V.

[0055] To sum up, the present application includes at least one of the following beneficial technical effects: the solution in the present application provides a standardized process for deep processing of armored thermocouples, effectively improves production efficiency, and the treatment of moisture in the process is more standardized and reasonable, which can effectively ensure the yield rate of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0057] Figure 1 It is the overall flow chart of the armored thermocouple processing technology;

[0058] Figure 2 It is a schematic diagram of the structural changes of the armored thermocouple during the heat treatment process;

[0059] Figure 3 It is a schematic diagram of the structural changes of the armored thermocouple during the cold treatment process;

[0060] Figure 4 It is a flow chart of moisture treatment determination.

[0061] Reference numerals: Figure 1 、 Figure 2 and Figure 3 , is a processing technology for an armored thermocouple provided in this application, which includes the following steps:

[0062] Raw material processing: The raw materials are initially purchased in coils. The open ends of the coiled cables need to be sealed with wax, and the humidity in the production workshop must be maintained below 30% during the production process. In other optional embodiments, the cables can also be stored in an oven set at 160°C.

[0063] Processing also includes:

[0064] Step 1: Straighten and cut. Cut different lengths flexibly according to needs and ensure that the metal sleeve 1 is straight. Use a lathe and a steel pipe or a through pipe for straightening. You can also use a commonly used straightening machine on the market for correction. Then use a cutter to cut. After cutting, use rubber caps to cover both ends of the metal sleeve 1 to prevent moisture from entering. For easy identification, the rubber caps at both ends of the metal sleeve 1 are of different lengths. In other optional embodiments, they can also be made in different colors. When the quantity meets the demand, re-coil the raw materials and seal the tail ends of the raw materials with a glue stick or place the raw materials in an oven.

[0065] After cutting, the metal sleeve 1 is taken to a laser engraving machine for laser engraving. The engraving includes the production location + work order number + product serial number + supplier number, separated by a slash;

[0066] Step 2: Hot end treatment

[0067] 2.1. Grind the hot end to make the surface of the hot end smooth. Specifically, remove the hot end rubber cap and use a sanding machine to grind it flat;

[0068] 2.2. Sandblasting: Use a sandblasting machine to remove part of the magnesium oxide powder at the hot end of the metal sleeve 1, leaving a depth of L1. The reference standard is that the depth of the Φ6 metal sleeve 1-L1 is 4mm, the depth of Φ4.5-L1 is 3mm, the depth of Φ3-L1 is 2mm, and the depth of Φ2-L1 is 1.5mm;

[0069] Then, the depth L1 needs to be tested immediately using a testing jig. The testing jig includes a testing shaft 4 that can be plugged into and matched with the metal sleeve 1. The testing shaft 4 has an avoidance hole 41 for the thermocouple wire 3 to pass through. The outer wall of the testing shaft 4 is provided with a scale. During the test, the testing shaft 4 is inserted into the metal sleeve 1 and the scale is observed. The surface flatness of the magnesium oxide powder can be observed with the naked eye or flattened using the testing shaft 4. If necessary, it should be taken out for testing multiple times during the sandblasting process.

[0070] 2.3. Welding of thermocouple wires: Use a tungsten needle or needle-nosed pliers to center the wires together, and use an ion welder to weld the two wires together. Take photos to record the weld points. The weld points in the photos must be clear for easy product traceability. During the transfer process, if the hot end or cold end needs to be exposed to air for more than 30 seconds, it needs to be covered with a rubber cap.

[0071] 2.4. Close the hot end package. Use a fixture to hold the metal sleeve 1. Use a magnesium oxide powder spoon to fill the space with magnesium oxide powder to a depth of L1, leaving about 1 / 2 the thickness of the sealing sheet from the end of the metal sleeve 1. Then install the sealing sheet on the hot end and use a hammer to tighten the sealing sheet until the surface of the sealing sheet is flush with the end of the metal sleeve 1. The magnesium oxide powder must be dried on a heating plate set at 250°C in advance to ensure that the moisture content meets the requirements.

[0072] After the sealing is completed, moisture treatment is required before welding. The moisture treatment is to put the packaged metal sleeve 1 into an oven at a temperature of 300°C for a time of ≥8 hours.

[0073] 2.5. Welding the hot end seal: Heat the hot end area 20 to 30 mm long until it is red hot, weld the seal using argon arc welding, and finally weld the seal to the metal sleeve 1;

[0074] After welding, the hot end diameter size needs to be checked to see if it can pass the gauge normally. If the tail end size has expanded, it needs to be ground down with a belt sander so that it can pass the gauge smoothly.

[0075] Step 3: Cold end treatment

[0076] 3.1. Cutting and breaking the cold end: Use a stainless steel pipe cutter on a lathe to carve a groove at the required length of the cold end and slightly break the cold end. Perform ultrasonic vibration separation, leaving a thermocouple wire 3 with a length of L2.

[0077] 3.2. Sandblasting: Use a sandblasting machine to clean the residue on the inner and outer walls and the wires, and remove some magnesium oxide. Leave a space of depth L3 in the cold end. The calculation rules of L3 are the same as L1. At this time, a detection fixture is also required for the detection process;

[0078] 3.3. Preparation before sealing: bake to remove moisture;

[0079] Reference Figure 4 , the magnesium oxide powder needs to be tested for insulation to determine moisture, including the following determination steps:

[0080] Step a: Lower the oven temperature from 400°C to 160°C and maintain the temperature for 1 hour, taking 1-3 pieces of the product out of the oven at a time.

[0081] Step b: perform an insulation test using an insulation resistance tester to ensure that the insulation is ≥ 2000MΩ / 500V. If the insulation does not meet the requirements, the metal sleeve 1 needs to be placed in the oven and baked according to step a.

[0082] 3.4, Sealing,

[0083] The preparation of glue includes the following steps:

[0084] Step 1. Shake the curing agent for at least 3 minutes;

[0085] Step 2: Stir the epoxy resin glue for at least 3 minutes;

[0086] Step 3. After stirring evenly, mix the curing agent and epoxy resin glue in a ratio of 3:20, and stir for at least 3 minutes after mixing;

[0087] Step 4. Use containers to measure and hold epoxy resin glue and curing agent.

[0088] Among them, after opening the new glue bottle, the first time it is used, it is necessary to use a stirring tool to stir the sediment at the bottom of the bottle thoroughly; the glue is generally prepared in advance and ready for use;

[0089] Inject glue into the syringe, use a metal wire to expel the air from the syringe and glue, remove the metal sleeve 1 from the oven, take out 1 to 3 pieces at a time, place them on the baking tray, and start dispensing glue;

[0090] 3.5. Let it dry, place the glued metal sleeve 1 vertically on the baking tray and let it stand for 0.5 hours;

[0091] 3.6, Baking glue, the metal casing after dispensing glue 1 Baking time and temperature requirements: 100 ℃ baking for 1h, then 120 ℃ baking for 2h,

[0092] The secondary sealing of the cold end includes the following steps:

[0093] Step m: Lower the oven temperature to about 30° to 50° after the glue is baked in step 3.6 to facilitate the subsequent secondary sealing glue to flow evenly;

[0094] Step n, inject the epoxy glue into the syringe, and use a thin wire to expel the air from the needle end of the syringe;

[0095] Step o: Take out a number of metal sleeves 1 from the oven each time, and use a syringe to evenly dispense glue to cover the previous sealing position, ensuring that there are no bubbles;

[0096] Step P: Place the MIC baking tray into the oven and bake at 120 degrees for 2 hours.

[0097] Step 4: Insulation testing; including:

[0098] After being placed in boiling water at 100°C for 10 to 15 minutes, an insulation test is performed to ensure that the insulation is 10,000MΩ / 500V. In other optional embodiments, the insulation test can also be performed at 500°C so that the insulation test is greater than 10MΩ / 500V.

[0099] Step 5: Polishing post-processing: smooth the end of the thermocouple wire 3. When the length of the metal sleeve 1 plus the exposed thermocouple wire 3 is greater than 100 mm, polish 50 mm from the hot end. When the length of the metal sleeve 1 plus the exposed thermocouple wire 3 is less than 100 mm, no polishing is required. DETAILED DESCRIPTION

[0100] The following is combined with Figure 1-4This application is described in further detail.

[0101] Reference Figure 1 、 Figure 2 and Figure 3 , is a processing technology for an armored thermocouple provided in this application, which includes the following steps:

[0102] Raw material processing: The raw materials are initially purchased in coils. The open ends of the coiled cables need to be sealed with wax, and the humidity in the production workshop must be maintained below 30% during the production process. In other optional embodiments, the cables can also be stored in an oven set at 160°C.

[0103] Processing also includes:

[0104] Step 1: Straighten and cut. Cut different lengths flexibly according to needs and ensure that the metal sleeve is straight. Use a lathe and a steel pipe or a through pipe for straightening. You can also use a commonly used straightening machine on the market for correction. Then use a cutter to cut. After cutting, use rubber caps to cover both ends of the metal sleeve to prevent moisture from entering. For easy identification, the rubber caps at both ends of the metal sleeve are of different lengths. In other optional embodiments, they can also be made in different colors. When the quantity meets the requirements, re-coil the raw materials and seal the tail ends of the raw materials with a glue stick or place the raw materials in an oven.

[0105] After cutting, take the metal sleeve to the laser engraving machine for laser engraving. The engraving includes the production location + work order number + product serial number + supplier number, separated by slashes;

[0106] Step 2: Hot end treatment

[0107] 2.1. Grind the hot end to make the surface of the hot end smooth. Specifically, remove the hot end rubber cap and use a sanding machine to grind it flat;

[0108] 2.2. Sandblasting: Use a sandblasting machine to remove part of the magnesium oxide powder at the hot end of the metal sleeve, leaving a depth of L1. The reference standard is that the depth of L1 of the Φ6 metal sleeve is 4mm, the depth of L1 of Φ4.5 is 3mm, the depth of L1 of Φ3 is 2mm, and the depth of L1 of Φ2 is 1.5mm.

[0109] Then, the depth L1 needs to be tested immediately using a testing fixture. The testing fixture includes a testing shaft that can be plugged into a matching metal sleeve. There is a hole in the testing shaft for the thermocouple wire to pass through. The outer wall of the testing shaft is provided with a scale. When testing, the testing shaft is inserted into the metal sleeve and the scale is observed. The surface flatness of the magnesium oxide powder can be observed with the naked eye or flattened using the testing shaft. If necessary, it should be taken out for testing multiple times during the sandblasting process.

[0110] 2.3. Thermocouple wire welding: Use a tungsten needle or needle-nose pliers to center the wires together, and use an ion welder to weld the two wires together. Take photos to record the weld points. The weld points in the photos must be clear for easy product traceability. During the transfer process, if the hot end or cold end needs to be exposed to air for more than 30 seconds, it needs to be covered with a rubber cap.

[0111] 2.4. Close the hot end package. Hold the metal sleeve with a fixture and use a magnesium oxide powder spoon to fill the space with magnesium oxide powder to a depth of L1, leaving about 1 / 2 the thickness of the sealing sheet between the end of the metal sleeve and the magnesium oxide powder. Then install the sealing sheet on the hot end and use a hammer to tighten the sealing sheet until the surface of the sealing sheet is flush with the end of the metal sleeve. The magnesium oxide powder must be dried on a heating plate set at 250°C in advance to ensure that the moisture content meets the requirements.

[0112] After the sealing is completed, moisture treatment is required before welding. The moisture treatment is to put the packaged metal sleeve into the oven at a temperature of 300°C for a time of ≥8 hours.

[0113] 2.5. Hot end sealing piece welding: Heat the hot end area of ​​20 to 30 mm in length until it is red, weld the sealing piece with argon arc welding, and finally weld the sealing piece to the metal sleeve;

[0114] After welding, the hot end diameter size needs to be checked to see if it can pass the gauge normally. If the tail end size has expanded, it needs to be ground down with a belt sander so that it can pass the gauge smoothly.

[0115] Step 3: Cold end treatment

[0116] 3.1. Cutting and breaking the cold end: Use a stainless steel pipe cutter on a lathe to carve a groove at the required length of the cold end and slightly break the cold end. Perform ultrasonic vibration separation and leave a thermocouple wire of length L2.

[0117] 3.2. Sandblasting: Use a sandblasting machine to clean the residue on the inner and outer walls and the wires, and remove some magnesium oxide. Leave a space of depth L3 in the cold end. The calculation rules of L3 are the same as L1. At this time, a detection fixture is also required for the detection process;

[0118] 3.3. Preparation before sealing: bake to remove moisture;

[0119] Reference Figure 4 , the magnesium oxide powder needs to be tested for insulation to determine moisture, including the following determination steps:

[0120] Step a: Lower the oven temperature from 400°C to 160°C and maintain the temperature for 1 hour, taking out 1-3 pieces of the product from the oven at a time.

[0121] Step b: perform insulation testing using an insulation resistance tester to ensure that the insulation is ≥ 2000MΩ / 500V. If the insulation does not meet the requirements, the metal sleeve needs to be placed in the oven and baked according to step a.

[0122] 3.4, Sealing,

[0123] The preparation of glue includes the following steps:

[0124] Step 1. Shake the curing agent for at least 3 minutes;

[0125] Step 2: Stir the epoxy resin glue for at least 3 minutes;

[0126] Step 3. After stirring evenly, mix the curing agent and epoxy resin glue in a ratio of 3:20, and stir for at least 3 minutes after mixing;

[0127] Step 4. Use containers to measure and hold epoxy resin glue and curing agent.

[0128] Among them, after opening the new glue bottle, the first time it is used, it is necessary to use a stirring tool to stir the sediment at the bottom of the bottle thoroughly; the glue is generally prepared in advance and ready for use;

[0129] Inject glue into the syringe, use a metal wire to expel the air from the syringe and glue, remove the metal sleeve from the oven, take out 1 to 3 pieces at a time, place them on the baking tray, and start dispensing glue;

[0130] 3.5. Let it dry, place the glued metal sleeve vertically on the baking tray and let it stand for 0.5 hours;

[0131] 3.6. Baking: The metal casing after dispensing glue has the following baking time and temperature requirements: bake at 100℃ for 1 hour, then bake at 120℃ for 2 hours.

[0132] The secondary sealing of the cold end includes the following steps:

[0133] Step m: Lower the oven temperature to about 30° to 50° after the glue is baked in step 3.6 to facilitate the subsequent secondary sealing glue to flow evenly;

[0134] Step n, inject the epoxy glue into the syringe, and use a thin wire to expel the air from the needle end of the syringe;

[0135] Step o: Take out several metal sleeves from the oven each time, and use a syringe to evenly apply glue to cover the previous sealing position, ensuring that there are no bubbles;

[0136] Step P: Place the MIC baking tray into the oven and bake at 120 degrees for 2 hours.

[0137] Step 4: Insulation testing; including:

[0138] After being placed in boiling water at 100°C for 10 to 15 minutes, an insulation test is performed to ensure that the insulation is 10,000MΩ / 500V. In other optional embodiments, the insulation test can also be performed at 500°C so that the insulation test is greater than 10MΩ / 500V.

[0139] Step 5: Polishing treatment: smooth the end of the thermocouple wire. When the length of the metal sleeve plus the exposed thermocouple wire is greater than 100mm, polish 50mm from the hot end. When the length of the metal sleeve plus the exposed thermocouple wire is less than 100mm, no polishing is required.

[0140] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A process for processing armored thermocouples, characterized in that: The following steps are involved: Step 1: Straighten and cut; Step 2: Hot end treatment 2.

1. Grind the hot end to make the hot end surface smooth. 2.

2. Sandblasting: remove part of the magnesium oxide powder from the hot end of the metal sleeve (1), leaving a depth of L1. 2.

3. Thermocouple wire (3) welding process, 2.

4. Close the hot end. Fill the space with magnesium oxide powder into the depth L1 and install the sealing piece to the hot end. The magnesium oxide powder needs to be dried on the heating plate in advance. The heating plate is set at 250℃. 2.

5. Welding the sealing piece to the metal sleeve (1); Step 3: Cold end treatment 3.

1. Cutting and breaking of the cold end, 3.

2. Sandblasting: Use a sandblasting machine to clean the inner and outer walls and the residue on the wires, and remove some magnesium oxide, leaving a space of depth L3 in the cold end. 3.

3. Preparation before sealing: bake in the oven to remove moisture. 3.

4. Sealing: Take out the metal sleeves (1) from the oven, take out 1 to 3 at a time, place them on the baking tray and start applying glue. 3.

5. Dry, place vertically on a baking tray, and let it stand for more than 0.5 hours. 3.

6. Baking glue: the time and temperature requirements for baking glue are: first bake at 100℃ for 1 hour, then bake at 120℃ for 2 hours; Step 4: Insulation test to ensure insulation; Step 5: Polishing post-processing, smoothing the end of the thermocouple wire (3). When the length of the metal sleeve (1) plus the exposed thermocouple wire (3) is greater than 100 mm, polishing is performed 50 mm from the hot end. When the length of the metal sleeve (1) plus the exposed thermocouple wire (3) is less than 100 mm, polishing is not required.

2. The armored thermocouple processing technology according to claim 1, characterized in that: In steps 1 to 4, if either end of the metal sleeve (1) needs to be exposed to the air for more than 3 minutes, a rubber sleeve must be installed on the end of the metal sleeve (1). The two rubber sleeves on the same metal tube have a distinguishing structure for distinguishing the hot end and the cold end.

3. The armored thermocouple processing technology according to claim 2, characterized in that: L1 follows the following standard parameters: Φ6 metal sleeve (1)-L1 depth 4mm, Φ4.5-L1 depth 3mm, Φ3-L1 depth 2mm, Φ2-L1 depth 1.5mm, L3 is calculated in the same way as L1.

4. The armored thermocouple processing technology according to claim 2, characterized in that: After step 2.2, the depth L1 needs to be detected using a detection jig, which includes a detection shaft (4) that can be plugged into and configured with a matching metal sleeve (1), a relief hole (41) for the thermocouple wire (3) to pass through is opened in the detection shaft (4), and a scale is provided on the outer wall of the detection shaft (4).

5. The armored thermocouple processing technology according to claim 2, characterized in that: After step 1, the metal sleeve (1) needs to be taken to a laser engraving machine for laser engraving.

6. The armored thermocouple processing technology according to claim 5, characterized in that: After step 2.3, take photos to record the solder joints. The solder joints in the photos must be clear to facilitate product traceability.

7. The armored thermocouple processing technology according to claim 6, characterized in that: Between step 2.4 and step 2.5, the packaged metal sleeve (1) needs to be placed in an oven at a temperature of 300°C-400°C for a time of ≥8 hours.

8. The armored thermocouple processing technology according to claim 1 or 7, characterized in that: Before welding the seal, heat the area 20 to 30 mm long at the hot end until it is red, and weld the seal using argon arc welding.

9. The armored thermocouple processing technology according to claim 8, characterized in that: After welding, check the hot end diameter to see if it can pass the gauge normally. If the tail end size has expanded, use a belt sander to grind it down so that it can pass the gauge smoothly.

10. The armored thermocouple processing technology according to claim 9, characterized in that: Before proceeding to step 3.4, the magnesium oxide powder needs to be tested for insulation to determine moisture, including the following determination steps: Step a: Lower the oven temperature from 400°C to 160°C and maintain the temperature for 1 hour, taking out 1-3 pieces of the product from the oven at a time. Step b: perform insulation test using an insulation resistance tester to ensure that the insulation is ≥ 2000MΩ / 500V. If the insulation does not meet the requirements, the metal sleeve (1) needs to be placed in the oven for further baking.

11. The armored thermocouple processing technology according to claim 1, characterized in that: The preparation of the glue in step 3.4 includes the following steps: Step 1. Shake the curing agent for at least 3 minutes; Step 2: Stir the epoxy resin glue for at least 3 minutes; Step 3. After stirring evenly, mix the curing agent and epoxy resin glue in a ratio of 3:20, and stir for at least 3 minutes after mixing; Among them, after opening the new bottle of glue, when using it for the first time, you need to use a stirring tool to stir the sediment at the bottom of the bottle thoroughly; Step 4. Use a measuring container to hold the mixture of epoxy resin glue and curing agent.

12. The armored thermocouple processing technology according to claim 1, characterized in that: After step 3.6, the cold end needs to be sealed again, which includes the following steps: Step m: After baking the glue, lower the oven temperature to 30-50°C to facilitate even glue flow during the second sealing; Step n, inject the epoxy glue into the syringe, and use a thin wire to expel the air from the needle end of the syringe; Step o, taking out a number of metal sleeves (1) from the oven each time, using a syringe to dispense glue evenly to cover the previous sealing position, ensuring that there are no bubbles; Step P: Place the metal sleeve (1) on a baking tray and put it into an oven, baking it at 120 degrees for 2 hours.

13. The armored thermocouple processing technology according to claim 12, characterized in that: The insulation testing process in step 4 includes: After being placed in 100℃ boiling water for 10-15 minutes, the insulation test is carried out to ensure the insulation is 10000MΩ / 500V.

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