CN117928750A

CN117928750A - High-temperature thermocouple probe shell and sensor brazing method using probe

Info

Publication number: CN117928750A
Application number: CN202311682597.8A
Authority: CN
Inventors: 王振廷; 齐娜; 于建楠; 王永鹏; 刘海龙
Original assignee: CETC 49 Research Institute
Current assignee: CETC 49 Research Institute
Priority date: 2023-12-08
Filing date: 2023-12-08
Publication date: 2024-04-26

Abstract

A high-temperature thermocouple probe shell and a sensor brazing method using the probe relate to the field of sensor preparation. The invention solves the problem that the joint of the existing steel structure assembled water treatment device is easy to leak. The first pipe body, the connecting section and the second pipe body are sequentially connected from left to right and are manufactured into a whole, and the outer side end surface of the second pipe body is provided with a conical hole. Step one: processing a high-temperature thermocouple probe shell; step two: thoroughly cleaning the surface of a welding area before welding, and polishing by using sand paper to ensure that the base metal is welded in a smooth state as much as possible; step three: the armored thermocouple is insulated, and the insulation resistance between the core wire and the probe shell of the high-temperature thermocouple is more than 1000MΩ/100VDC; step four: the armored thermocouple is arranged on the clamp for fixing during welding; step five: BNi-2 solder is selected for welding between the probe end shell part and the armored thermocouple; step six: inspection after welding. The invention is used for sensor brazing.

Description

High-temperature thermocouple probe shell and sensor brazing method using probe

Technical Field

The invention relates to the field of sensor preparation, in particular to a high-temperature thermocouple probe shell and a sensor brazing method using the probe.

Background

The fuel temperature sensor adopts vacuum brazing welding at two ends of the joint of the probe shell and the armored thermocouple. Vacuum brazing is to join a solder material to a base material by melting by heating under vacuum conditions. During vacuum brazing, the temperature in the heating furnace is heated to be between the melting point of the brazing filler metal and the melting point of the base metal, and the connection between the brazing filler metal and the base metal is completed by utilizing the flowing, diffusion and solidification of the liquid phase brazing filler metal. And compared with the high temperature of an electric arc, the brazing temperature is lower, the influence on a base metal is smaller, a heat affected zone hardly appears, the quality of a joint is greatly improved, and a brazing welding mode is selected.

The basic principle of realizing vacuum brazing is as follows:

(1) Wettability of the solder. The surface of the base metal can be wetted by the brazing filler metal to form a brazing weld, and the wetting process of the brazing filler metal in the brazing process belongs to spreading wetting, namely, liquid drops of the liquid brazing filler metal spread on the surface of the base metal. Good wettability ensures a tight bond between the braze and the base material to obtain a joint of sufficient strength.

(2) Capillary action. The liquid which can infiltrate the inner wall of the tubule generates a bending liquid level in the tubule, thereby generating additional pressure, and the phenomenon that the liquid rises is the capillary action phenomenon. Before brazing, the contact surface of the base metal is ensured to be smooth during assembly, and the small and uniform gap width is controlled. Because the brazing gap is smaller, the capillary action is obvious, and the brazing is kept for a period of time during brazing, so that the brazing filler metal is melted, and the liquid brazing filler metal flows to fill the welding seam under the action of the capillary force.

(3) Vacuum degree. At high temperature, the vacuum condition is favorable for decomposing and volatilizing oxides, so that oxide films on the surfaces of the materials are removed, and the solder is ensured to wet the base materials of the materials. And the vacuum environment does not contain impurities, which is more beneficial to the protection during high-temperature brazing, so that a brazing mode is selected.

By searching the intensity of the solder used by the product, when the welding depth is 1mm, the upper limit of the shearing force of the solder can be reached by externally applying 52MPa (under the condition of 850 ℃), which is larger than the highest 14.4MPa pressure outside the product. Under the condition of sufficient solder, the welding design is reasonable, and the strength requirement can be met.

The technological parameters affecting the welding quality mainly include welding time, temperature and solder consumption, and if one of the three parameters is abnormal, the welding quality can be affected.

Aiming at the specification of the external cooperation technology of the product, the welding temperature is 1060+/-5 ℃, the heat preservation time is 20+/-1 min, and the welding strength and quality of the product can be ensured. Before welding, the welding flux is uniformly smeared into a circle at the joint of the armored thermocouple and the probe shell to form a conical shape.

Since the filling amount of the solder is not specified in detail in technical Specification, the solder is not filled sufficiently in actual operation, and certain difference exists in the filling amount of the solder each time, which may cause insufficient solder, cause gaps at the welding seam of the product, and finally cause leakage of the product.

In summary, in the existing fuel temperature sensor, the problem of leakage of the fuel temperature sensor is caused by insufficient solder filling in the welding process.

Disclosure of Invention

The invention aims to solve the problem that the existing fuel temperature sensor is leaked due to insufficient filling of solder in the welding process, and further provides a thermocouple probe shell and a sensor brazing method using the probe.

The technical scheme of the invention is as follows:

The utility model provides a thermocouple probe shell includes first body, linkage segment and second body, and first body, linkage segment and second body have a left side to right and connect gradually and make integrative, and first body, linkage segment and the coaxial setting of second body, wherein, the bell mouth has been seted up to the outside terminal surface of second body.

Further, the taper of the tapered bore is 40 ° -70 °.

Preferably, the taper of the tapered bore is 50 °, 55 °, 60 ° or 65 °.

Further, the bore diameter of the second pipe body is phi 1.5mm, the upper deviation is +0.050mm, the lower deviation is +0.025mm, and the length of the inner bore of the second pipe body is 50mm.

Preferably, the inner bore of the second tubular body is machined using slow wire cutting.

Further, the outer diameter of the first tube body is smaller than the outer diameter of the second tube body.

Further, the connecting section comprises an outer arc section and a boss, and the outer arc section and the boss are sequentially connected from left to right and are manufactured into a whole.

Preferably, the first pipe body, the connecting section and the second pipe body are all made of nickel-based superalloy GH 3030.

The invention also provides a sensor brazing method, which comprises the following steps:

step one: processing a high-temperature thermocouple probe shell;

Machining according to GB/T1804-m level according to linear dimension non-injection tolerance in the outline drawing;

Step two: thoroughly cleaning the surface of a welding area before welding, and polishing by using sand paper to ensure that the base metal is welded in a smooth state as much as possible;

Step three: the armored thermocouple is insulated, and the insulation resistance between the core wire and the probe shell of the high-temperature thermocouple is more than 1000MΩ/100VDC;

step four: the armored thermocouple is arranged on the clamp for fixing during welding;

Step five: BNi-2 solder is selected for welding between the probe end shell part and the armored thermocouple;

step five: manufacturing a clamp bottom plate by adopting stainless steel, and manufacturing two omega-shaped hoops to respectively fix a high-temperature thermocouple probe shell and an armored thermocouple wire, wherein a vernier caliper is adopted to ensure that the front end of the armored thermocouple wire leaks out by 3+/-0.1 mm during fixing;

Step five: spreading the prepared BNi-2 solder on the contact positions of the front end and the rear end of the outer shell of the thermocouple probe and the armored thermocouple wire respectively by using tweezers, accommodating the solder through a conical hole, enabling the solder to enter the inner holes of the armored thermocouple wire and the outer shell of the thermocouple probe, so that the solder is spread to a full state, and standing for a period of time to solidify the solder;

step five: and (3) placing the armored thermocouple into a brazing furnace, and vacuumizing the brazing furnace before welding, wherein the temperature is 1060 ℃ for 20min.

Step six: inspection after welding:

After welding, each product is subjected to CT inspection and pressure resistance test, and the welding part meeting the requirements of the two products can be transferred to the next working procedure.

Further, the number of times of welding in the fifth step is 2.

Compared with the prior art, the invention has the following effects:

1. Because the second pipe body 3 of the high-temperature thermocouple probe shell is provided with the conical hole 4, the conical hole 4 can contain more solder, and the solder can be ensured to be smoothly filled into the gap between the armored thermocouple wire and the inner hole of the high-temperature thermocouple probe shell, so that the leakage problem caused by insufficient filling of the solder is avoided.

2. The invention definitely limits the machining precision of the inner hole of the high-temperature thermocouple probe shell, has small machining error, ensures that the unilateral gap between the armored thermocouple wire and the inner hole of the high-temperature thermocouple probe shell is 0.04-0.11mm, and improves the machining precision of the high-temperature thermocouple probe shell.

Drawings

FIG. 1 is a schematic diagram of the structure of a thermocouple probe housing of the present invention;

FIG. 2 is a schematic view of the weld condition of the present invention;

FIG. 3 is an outline view of a CW-5106 type fuel temperature sensor equipped with the probe housing of the thermocouple of the present invention.

Detailed Description

The first embodiment is as follows: referring to fig. 1, the present embodiment includes a first pipe body 1, a connection section 2, and a second pipe body 3, where the first pipe body 1, the connection section 2, and the second pipe body 3 are sequentially connected from left to right and are integrally formed, and the first pipe body 1, the connection section 2, and the second pipe body 3 are coaxially disposed, and a tapered hole 4 is formed in an outer end surface of the second pipe body 3.

Referring to fig. 3, in the practical use of the present embodiment, the fuel temperature sensor includes a probe outer joint 10, a probe housing 11 of the thermocouple, a thermocouple 12, a metal adapter tube 13, a heat shrinkage tube 14 with glue, and an electrical connector 15, the probe outer joint 10 is sleeved on the connecting section 2 of the probe housing 11 of the thermocouple, one end of the thermocouple 12 is coaxially inserted into the inner hole of the probe housing 11 of the thermocouple, and the other end of the thermocouple 12 is connected with the metal adapter tube 13, the heat shrinkage tube 14 with glue, and the electrical connector 15 from left to right. The welding part is mainly a circular ring space between the thermocouple 12 and the inner hole of the thermocouple probe shell 11, and two end parts when the thermocouple 12 extends out of the inner hole of the thermocouple probe shell 11.

The second embodiment is as follows: the present embodiment will be described with reference to fig. 1, in which the taper of the tapered hole 4 is 40 ° -70 °. The arrangement is convenient for the solder to smoothly enter into the gap between the armored thermocouple wire and the inner hole of the outer shell of the thermocouple probe. Other compositions and connection relationships are the same as those of the first embodiment.

And a third specific embodiment: the taper of the tapered hole 4 of the present embodiment is 50 °, 55 °,60 °, or 65 ° described with reference to fig. 1. So arranged, this effect is optimal. Other compositions and connection relationships are the same as those of the first or second embodiment.

The specific embodiment IV is as follows: the present embodiment will be described with reference to fig. 1, in which the bore diameter of the second tube 3 is Φ1.5mm, the upper deviation is +0.050mm, the lower deviation is +0.025mm, and the bore length of the second tube 3 is 50mm. The welding device is high in precision, the smooth flow of the brazing filler metal is facilitated, the welding quality is guaranteed, and the welding seam is avoided. Other compositions and connection relationships are the same as those of the first, second or third embodiments.

Fifth embodiment: the present embodiment will be described with reference to fig. 1, in which the inner hole of the second pipe body 3 is machined by slow wire cutting. So set up, the machining precision is higher. Other compositions and connection relationships are the same as those of the first, second, third or fourth embodiments.

Specific embodiment six: in the present embodiment, referring to fig. 1, the outer diameter of the first pipe body 1 is smaller than the outer diameter of the second pipe body 3. So arranged, the second pipe body 3 is fixed on the frame body when being welded, and other components and connection relations are the same as those of the first, second, third, fourth or fifth embodiments.

Seventh embodiment: the connection section 2 of the present embodiment includes the outer arc section 2-1 and the boss 2-2, and the outer arc section 2-1 and the boss 2-2 are sequentially connected from left to right and are integrally formed with each other, as described with reference to fig. 1. So set up, form ball seal structure between outer circular arc section 2-1 and the inside wall of external joint, sealed effectual, boss 2-2 are used for fixed probe external joint 10, improve the intensity of thermocouple probe shell. Other compositions and connection relationships are the same as those of the first, second, third, fourth, fifth or sixth embodiments.

Eighth embodiment: referring to fig. 1, the first pipe body 1, the connecting section 2, and the second pipe body 3 according to this embodiment are all made of the nickel-based superalloy GH 3030. By the arrangement, the alloy has excellent high-temperature strength, good oxidation resistance and hot corrosion resistance, and meanwhile, the cutting force required by the high-strength material per se is 2-5 times that of common alloy steel during processing, so that the processing difficulty is high.

Detailed description nine: the sensor brazing method of the present embodiment will be described with reference to fig. 1, and includes the steps of:

step one: processing a high-temperature thermocouple probe shell;

Step five: spreading the prepared BNi-2 solder on the contact positions of the front end and the rear end of the outer shell of the thermocouple probe and the armored thermocouple wire respectively by using tweezers, accommodating the solder through the conical hole 4, enabling the solder to enter the inner holes of the armored thermocouple wire and the outer shell of the thermocouple probe, so that the solder is spread to a full state, and standing for a period of time to solidify the solder;

Step six: inspection after welding:

BNi-2 brazing solder is selected between the shell part of the probe end and the armored thermocouple for welding through characteristic comparison and the like in order to ensure good welding effect of the probe end of the product. GH3030 (Ni and Cr are the main amounts and C, ti, al, fe, mn, si, P, S are small amounts) is selected for the probe shell and the armored thermocouple shell, the selected BNi-2 solder also uses Ni and Cr as main components, and the solder has the same matrix elements as the base metal, so that a good welding effect can be achieved.

The verification mode in the step six is as follows: ① 8 products are used for welding verification, and three comparison groups are respectively formed before welding according to the installation state of the products: the installation direction of the product, whether the thermocouple wires are polished by fine sand paper before installation or not, and the proportion concentration of the brazing filler metal. And (3) performing braze welding according to the original technological parameters (1060 ℃ C., 20 min).

② Taking 5 products of the first welding, performing secondary coating, performing secondary welding, and performing CT photographing inspection again after welding;

③ After the secondary welding CT photographing inspection, a withstand voltage test is carried out, and the test conditions are as follows: the pressure is 14.4MPa and the dwell time is 5min. All the verification products have no leakage phenomenon in the pressure test, and meet the requirements.

The nickel-based solder contains Cr element, and has the function of enhancing the corrosion resistance, oxidation resistance and high temperature resistance of the solder. The specific chemical composition of the solder is shown in table 1.

TABLE 1BNi-2 solder chemistry

Chemical composition

Cs

B

Si

Cr

Fe

Ni

Content (%)

≤0.06

2.75～3.5

4-5

6.0-8.0

2.5-3.5

Allowance of

BNi-2 solder is selected as the product of the batch, and BNi-2: one of the nickel-based solders has a solidus temperature of 971 ℃, a liquidus temperature: 999 ℃. In the brazing process, the BNi-2 has lower melting temperature than other nickel-based solders, has good wettability, and the formed braze joint has good high-temperature strength and good oxidation resistance and corrosion resistance.

Compared with other solders, the nickel-based solder is more suitable for vacuum brazing of high-temperature alloys, and the components of the nickel-based solder do not contain elements with high vapor pressure such as Ag, zn and the like, so that the volatilization of the solder during brazing is less, and the vacuum degree during brazing can be ensured.

Detailed description ten: the present embodiment will be described with reference to fig. 1 to 3, in which the number of welds in step five of the present embodiment is 2.

The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1.A high temperature thermocouple probe shell is characterized in that: the novel pipe joint comprises a first pipe body (1), a connecting section (2) and a second pipe body (3), wherein the first pipe body (1), the connecting section (2) and the second pipe body (3) are sequentially connected left to right and are integrally manufactured, the first pipe body (1), the connecting section (2) and the second pipe body (3) are coaxially arranged, and a conical hole (4) is formed in the outer side end face of the second pipe body (3).

2. The thermocouple probe housing according to claim 1, wherein: the taper of the conical hole (4) is 40-70 degrees.

3. The thermocouple probe housing according to claim 2, wherein: the taper of the conical hole (4) is 50 degrees, 55 degrees, 60 degrees or 65 degrees.

4. A thermocouple probe housing according to claim 3, wherein: the bore diameter of the second pipe body (3) is phi 1.5mm, the upper deviation is +0.050mm, the lower deviation is +0.025mm, and the length of the inner bore of the second pipe body (3) is 50mm.

5. The thermocouple probe housing according to claim 4, wherein: and the inner hole of the second pipe body (3) is processed by adopting slow wire cutting.

6. A thermocouple probe housing according to claim 1 or 5, characterised in that: the outer diameter of the first pipe body (1) is smaller than that of the second pipe body (3).

7. The thermocouple probe housing according to claim 6, wherein: the connecting section (2) comprises an outer arc section (2-1) and a boss (2-2), and the outer arc section (2-1) and the boss (2-2) are sequentially connected from left to right and are manufactured into a whole.

8. The thermocouple probe housing according to claim 7, wherein: the first pipe body (1), the connecting section (2) and the second pipe body (3) are all made of nickel-based superalloy GH 3030.

9. A method of brazing a sensor using the thermocouple probe housing of claim 8, comprising the steps of:

step one: processing a high-temperature thermocouple probe shell;

Step five: spreading the prepared BNi-2 solder on the contact positions of the front end and the rear end of the outer shell of the thermocouple probe and the armored thermocouple wire respectively by using tweezers, accommodating the solder through a conical hole (4) and enabling the solder to enter the inner holes of the outer shell of the thermocouple wire and the thermocouple probe, so that the solder is spread to a full state and is placed for a period of time to solidify the solder;

Step six: inspection after welding:

10. A method of brazing a sensor according to claim 9, wherein: and in the fifth step, the welding times are 2 times.