CN117464325A - Integral machining method for thermowell - Google Patents
Integral machining method for thermowell Download PDFInfo
- Publication number
- CN117464325A CN117464325A CN202311569590.5A CN202311569590A CN117464325A CN 117464325 A CN117464325 A CN 117464325A CN 202311569590 A CN202311569590 A CN 202311569590A CN 117464325 A CN117464325 A CN 117464325A
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- thermowell
- tube head
- processing method
- blank
- machining
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- 238000003754 machining Methods 0.000 title claims abstract description 43
- 238000000034 method Methods 0.000 title claims abstract description 32
- 238000003466 welding Methods 0.000 claims abstract description 21
- 238000010438 heat treatment Methods 0.000 claims abstract description 20
- 238000005498 polishing Methods 0.000 claims abstract description 15
- 238000007789 sealing Methods 0.000 claims abstract description 14
- 238000003672 processing method Methods 0.000 claims abstract description 12
- 238000001816 cooling Methods 0.000 claims description 9
- 238000004321 preservation Methods 0.000 claims description 8
- 238000010079 rubber tapping Methods 0.000 claims description 4
- 230000008569 process Effects 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 244000137852 Petrea volubilis Species 0.000 abstract description 3
- 238000003825 pressing Methods 0.000 abstract description 3
- 230000007547 defect Effects 0.000 description 10
- 238000005260 corrosion Methods 0.000 description 8
- 230000007797 corrosion Effects 0.000 description 8
- 238000009659 non-destructive testing Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 230000002950 deficient Effects 0.000 description 4
- 238000007599 discharging Methods 0.000 description 4
- 230000008439 repair process Effects 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 230000003628 erosive effect Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000002040 relaxant effect Effects 0.000 description 2
- 230000003746 surface roughness Effects 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000010687 lubricating oil Substances 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000010070 molecular adhesion Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
Abstract
The invention discloses an integral machining method of a thermowell, and belongs to the technical field of thermocouple production. The invention discloses a thermowell integral processing method, which comprises the following steps: (1) manufacturing a ferrule; (2) welding and forming; (3) post-weld heat treatment; (4) rough machining; (5) finishing; (6) polishing. The finish machining means that the 6mm+4mm position of the sealing surface of the tube head of the thermowell is finished by a numerical control lathe, and then the polishing is carried out by using delta 10 multiplied by 25 multiplied by 250 flat pressing plate pad 400-mesh metallographic sand paper, so that the machining efficiency and precision can be improved, the roughness of the sealing surface of the tube head of the produced sleeve can reach Ra0.8μm, the sealing performance is excellent, the leakage of a measured medium is effectively prevented, and the occurrence of safety accidents is avoided.
Description
Technical Field
The invention belongs to the technical field of thermocouple preparation, and particularly relates to an integral machining method of a thermowell.
Background
The thermocouple is a temperature measuring element for measuring the temperature of a medium, converting a temperature signal into an electric signal, and converting the electric signal into the temperature through an instrument. Because the measured medium has the characteristics of high temperature, corrosion, high-speed flow and the like, a sleeve is generally used for protecting the thermocouple in order to prolong the service life of the thermocouple. The thermocouple is positioned within the thermowell so that the thermocouple does not need to withstand the corrosion and washout of the media. Thermowells are required to be resistant to high temperatures, chemical corrosion and erosion.
The thermowell material itself is critical. The influence factors of the measured medium, such as the concentration, temperature, speed, pH value, concentration of various active ions and the like of the fluid corrosive medium; the chemical composition, tissue structure, mechanical properties, corrosion resistance, stress or surface conditions of the thermowell material can affect the service life.
The existing thermowell integral processing method adopts a grinding machine for grinding, and needs to use a model for repeated debugging and taper verification, so that the efficiency is low.
Disclosure of Invention
In order to solve the problem of low machining efficiency in the prior art, the invention provides a method for integrally machining a thermowell, wherein the head of the thermowell is machined by adopting a build-up welding forming method, the material structure is compact, the nondestructive detection is free from defects, and the machining efficiency and the precision are improved by adopting an integral machining method (using a turning instead of grinding).
In a first aspect, the invention provides a thermowell integral processing method, comprising the steps of:
step one: determining the size and the inner diameter of a ferrule according to the tube head size in a thermowell drawing;
step two: welding rods are overlaid in the ferrules, the number of the ferrules is overlaid, and the blank length of the tube head is increased;
step three: after overlaying the blank to the size, carrying out heat treatment to eliminate stress, and cooling along with a furnace to obtain a blank of the pipe head;
step four: and (5) sequentially carrying out rough machining, finish machining and polishing on the tube head blank to obtain the finished product.
Further, the inner diameter of the ferrule is 5-6mm greater than the outer diameter dimension of the ferrule.
Further, the electrode is a STELLITE6 electrode.
Further, the heat treatment method is to put the materials into a resistance heating furnace for heating treatment, wherein the furnace temperature is less than or equal to 400 ℃, the heating speed is less than or equal to 120 ℃/h, the heat preservation temperature is 640-660 ℃, and the heat preservation time is 4-6h.
Further, the tapping temperature of the pipe head blank is less than or equal to 400 ℃, and the pipe head blank is air cooled after tapping.
Further, the rough machining method is grinding by a grinding machine, and the angle is 8-1' 30".
Further, the finish machining method is a numerical control lathe machining method, and finish machining is conducted on the position of the sealing surface of the pipe head blank, which is 6 mm+4mm.
Further, the polishing method comprises the following steps: polishing was performed with a delta 10X 25X 250 flat platen pad 400 mesh metallographic sandpaper for 1-2 minutes.
Compared with the prior art, the technical scheme provided by the embodiment of the application has at least the following advantages:
1. the invention discloses an integral machining method of a thermowell, which adopts a build-up welding forming method to machine the head of the thermowell, has compact material structure, shows no defect in nondestructive detection results, and improves the machining efficiency and precision by adopting the integral machining method (using a turning instead of grinding).
2. The invention discloses an integral machining method of a thermowell, and the produced tube head sealing surface has roughness of Ra0.8μm and excellent sealing performance. The leakage of the medium to be tested can be effectively prevented, and the occurrence of safety accidents is avoided.
3. The invention discloses an integral machining method of a thermowell, wherein a STELLITE6 cast rod is adopted for remelting and smelting by overlaying, and the tube head of the thermowell has higher high temperature resistance, chemical corrosion resistance and erosion corrosion resistance, so that the service life of the thermocouple is prolonged.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the description of the embodiments or the prior art will be briefly described below, and it will be obvious to those skilled in the art that other drawings can be obtained from these drawings without inventive effort.
FIG. 1 is a schematic view of a tube head for preparing a thermowell according to the present invention;
FIG. 2 is a schematic flow chart of the preparation of a thermowell (containing tube head) according to the present invention.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present application based on the embodiments herein.
Unless specifically indicated otherwise, the various raw materials, reagents, instruments, equipment, and the like used in this application are commercially available or may be prepared by existing methods.
In a first aspect, the present application provides a thermowell monolithic processing method, as shown in fig. 2, comprising the steps of:
(1) Manufacturing a ferrule; (2) welding and forming; (3) post-weld heat treatment; (4) rough machining; (5) finishing; (6) polishing.
The ferrule and the backing plate are tools for welding the thermocouple well pipe head, and subsequent rough machining can be removed; according to the tube head size (shown in figure 1) in the thermowell drawing, the size and the inner diameter of the ferrule are determined, and the inner diameter of the ferrule is 5-6mm larger than the outer diameter of the tube head, so that the tube head is ensured to have enough machining allowance.
The welding forming method comprises the following steps: and (3) overlaying STELLITE6 in the ferrules, superposing the number of the ferrules, and increasing the blank length of the tube head.
The method for heat treatment after welding comprises the following steps: carrying out heat treatment in time after welding, relaxing welding residual stress, and preventing cracks; the plasticity, fracture toughness and stress corrosion resistance of the surfacing metal are improved. After overlaying the blank to the size, placing the blank into a resistance heating furnace for stress relief treatment, wherein the furnace charging temperature is less than or equal to 400 ℃, the heating speed is not more than 120 ℃/h, the heat preservation temperature is 650+/-10 ℃, the heat preservation time is 4-6h, and the cooling mode is as follows: cooling along with the furnace, discharging at the temperature of less than or equal to 400 ℃, and cooling after discharging.
The rough machining refers to the rough machining of a tube head blank, and most of machining allowance (comprising a ferrule and a backing plate) is removed so as to prepare for nondestructive detection. If defects are found in the rough machining process or the nondestructive testing, repair welding is carried out on the defective parts after the defects are completely removed.
The finishing refers to finishing according to the figure, and the machining allowance is removed. And performing nondestructive testing again, and if defects are found in the nondestructive testing, performing repair welding on the defective parts after the defects are completely removed.
Wherein, polishing means that the sealing surface is polished after the grade I is detected to be qualified according to NB/T47013.5-2005 in a nondestructive test, and the roughness of the sealing surface reaches Ra0.8μm. The polishing method comprises the following steps: polishing with 400-mesh metallographic sand paper with delta 10×25×250 flat pressing plate pad for about 1-2min to obtain the final product.
Wherein Ra is a roughness symbol of the united states standard, and the conversion formula is: surface finish 14 grade = ra0.012 μm. Mean the average value of the absolute value of the distance between each point on the contour and the contour center line within a certain sampling length. Surface roughness is too large and too small to be wear resistant. The rougher the surface, the smaller the effective contact area between the mating surfaces, the greater the pressure, the greater the frictional resistance and the faster the wear. Too small a surface roughness can also lead to increased wear. Because the surface is too smooth, lubricating oil cannot be stored, an oil film is not easy to form between contact surfaces, and molecular adhesion is easy to occur so as to increase abrasion. For clearance fit, the rougher the surface is, the more easy the abrasion is, the clearance is gradually increased in the working process, and for interference fit, the actual effective interference is reduced and the connection strength is reduced because microscopic peaks are squeezed flat in assembly. The surface of rough parts presents large valleys which, like sharp notches and cracks, are very sensitive to stress concentrations, thus affecting the fatigue strength of the part. Most importantly, the rough surfaces do not closely conform to each other and gas or liquid leaks through the gaps between the contact surfaces, affecting the sealing performance of the sealing element.
In the invention, the precise machining of the thermowell is realized through a whole set of complete process flow. The finish machining method of the numerical control lathe is used for replacing the traditional grinding method of a grinding machine, the head of the thermowell is machined by adopting a build-up welding molding method, and the manufactured product material has precise and defect-free structure.
The principles and features of the present invention are described below in connection with the following examples, which are set forth to illustrate, but are not to be construed as limiting the scope of the invention. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Examples
The invention discloses an integral machining method of a thermowell, which comprises the following steps:
(1) And checking the technical requirements of the order and the drawing of the thermowell.
(2) Manufacturing a ferrule: the ferrule and the backing plate are tools for welding the thermowell tube head, and the subsequent rough machining is removal. According to the tube head size in the thermowell drawing, the size and the inner diameter of the ferrule are determined, and the inner diameter of the ferrule is 6mm larger than the outer diameter of the tube head, so that the tube head is ensured to have enough machining allowance.
(3) Welding and forming: and (3) overlaying STELLITE6 in the ferrules, superposing the number of the ferrules, and increasing the blank length of the tube head.
(4) Post-welding heat treatment: carrying out heat treatment in time after welding, relaxing welding residual stress, and preventing cracks; the plasticity, fracture toughness and stress corrosion resistance of the surfacing metal are improved. After overlaying the blank to the size, placing the blank into a resistance heating furnace for stress relief treatment, wherein the furnace charging temperature is 350 ℃, the heating rate is 100 ℃/h, the heat preservation temperature is 650 ℃, the heat preservation time is 5h, and the cooling mode is as follows: cooling along with the furnace, discharging at 350 ℃, and air cooling after discharging.
(5) Rough machining: and (3) rough machining is carried out on the tube head blank, most of machining allowance (comprising a ferrule and a backing plate) is removed, and preparation is carried out for nondestructive testing. If defects are found in the rough machining process or the nondestructive testing, repair welding is carried out on the defective parts after the defects are completely removed.
(6) And (3) finishing: and (3) carrying out finish machining according to the figure (the 6mm and 4mm positions of the sealing surface of the tube head are finished by a numerical control lathe), and removing machining allowance. And performing nondestructive testing again, and if defects are found in the nondestructive testing, performing repair welding on the defective parts after the defects are completely removed.
(7) Polishing: and (3) after the grade I is detected to be qualified according to NB/T47013.5-2005, polishing the sealing surface, and polishing with 400-mesh metallographic sand paper of a flat pressing plate pad with delta 10 multiplied by 25 multiplied by 250mm for 2 minutes, wherein the roughness of the sealing surface reaches Ra0.8μm.
Various embodiments of the present application may exist in a range format; it should be understood that the description in a range format is merely for convenience and brevity and should not be interpreted as a rigid limitation on the scope of the application. It is therefore to be understood that the range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that a description of a range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, wherever applicable. In addition, whenever a numerical range is referred to herein, it is meant to include any reference number (fractional or integer) within the indicated range.
In this application, unless otherwise indicated, terms of orientation such as "upper" and "lower" are used specifically to refer to the orientation of the drawing in the figures. In addition, in the description of the present application, the terms "include", "comprise", "comprising" and the like mean "including but not limited to". Relational terms such as "first" and "second", and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Herein, "and/or" describing an association relationship of an association object means that there may be three relationships, for example, a and/or B, may mean: a alone, a and B together, and B alone. Wherein A, B may be singular or plural. Herein, "at least one" means one or more, and "a plurality" means two or more. "at least one", "at least one" or the like refer to any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.
The foregoing is merely a specific embodiment of the application to enable one skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (8)
1. A method for integrally processing a thermowell, comprising the steps of:
step one: determining the size and the inner diameter of a ferrule according to the tube head size in a thermowell drawing;
step two: welding rods are overlaid in the ferrules, the number of the ferrules is overlaid, and the blank length of the tube head is increased;
step three: after overlaying the blank to the size, carrying out heat treatment to eliminate stress, and cooling along with a furnace to obtain a blank of the pipe head;
step four: and (5) sequentially carrying out rough machining, finish machining and polishing on the tube head blank to obtain the finished product.
2. The thermowell monolithic processing method according to claim 1, wherein the inner diameter of the ferrule is 5-6mm larger than the outer diameter dimension of the tube head.
3. The thermowell monolithic processing method according to claim 1, wherein the electrode is a STELLITE6 electrode.
4. The thermowell overall processing method according to claim 1, wherein the heat treatment method is to put the thermowell into a resistance heating furnace for heating treatment, wherein the furnace temperature is less than or equal to 400 ℃, the heating rate is less than or equal to 120 ℃/h, the heat preservation temperature is 640-660 ℃, and the heat preservation time is 4-6h.
5. The thermowell monolithic processing method according to claim 1, wherein the tapping temperature of the tube head blank is 400 ℃ or less, and air cooling is performed after tapping.
6. The thermowell monolithic processing method according to claim 1, wherein the rough processing method is grinding by a grinder at an angle of 8 ° -1'30".
7. The thermowell monolithic processing method according to claim 1, wherein the finishing method is a numerically controlled lathe process, finishing at 6mm+4mm of the tube head blank sealing surface.
8. The thermowell monolithic processing method according to claim 1, wherein the polishing method is: polishing was performed with a delta 10X 25X 250 flat platen pad 400 mesh metallographic sandpaper for 1-2 minutes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311569590.5A CN117464325A (en) | 2023-11-20 | 2023-11-20 | Integral machining method for thermowell |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311569590.5A CN117464325A (en) | 2023-11-20 | 2023-11-20 | Integral machining method for thermowell |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117464325A true CN117464325A (en) | 2024-01-30 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311569590.5A Pending CN117464325A (en) | 2023-11-20 | 2023-11-20 | Integral machining method for thermowell |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117464325A (en) |
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2023
- 2023-11-20 CN CN202311569590.5A patent/CN117464325A/en active Pending
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