CN114850710A

CN114850710A - Brazing method of large tube nest type radiator core assembly

Info

Publication number: CN114850710A
Application number: CN202210574521.2A
Authority: CN
Inventors: 潘峰; 吴长洪; 黄新友; 张�杰
Original assignee: Guizhou Yonghong Aviation Machinery Co Ltd
Current assignee: Guizhou Yonghong Aviation Machinery Co Ltd
Priority date: 2022-05-25
Filing date: 2022-05-25
Publication date: 2022-08-05
Anticipated expiration: 2042-05-25
Also published as: CN114850710B

Abstract

The invention discloses a brazing method of a stainless steel or high-temperature alloy large-scale tubular radiator core component, which starts from the aspects of brazing structure design, brazing tooling, brazing parameters and the like and comprises the steps of positioning welding, pipe penetrating, assembling, positioning welding, clamping, brazing filler metal coating, maximum temperature difference calculation, furnace entering, vacuum brazing, brazing parameter correction and the like. The large stainless steel or high-temperature alloy tubular radiator brazed by the invention can solve the series of problems of brazing deformation, radiating pipe dislocation, brazing filler metal loss and the like caused by brazing.

Description

Brazing method of large tube nest type radiator core assembly

Technical Field

The invention relates to a brazing method of a stainless steel or high-temperature alloy large-scale tubular radiator core component, in particular to a method in the aspects of brazing structure design, brazing filler metal coating, brazing tool design, brazing parameter setting and the like during radiator brazing.

Background

At present, the sealing modes of a radiating pipe and a core end plate of a core subassembly of the tube nest type radiator mainly comprise three modes of expansion joint, fusion welding and vacuum brazing. The vacuum brazing sealing performance can reach the strength equal to that of the base material, meanwhile, the welding deformation is small, and the vacuum brazing sealing device is particularly suitable for brazing sealing of the shell and tube radiator core assembly with the thin radiating tube wall (less than 0.5 mm) and the small arrangement distance (less than 2.0 mm). The shell and tube radiator is called as a micro-channel shell and tube radiator, has high radiating efficiency and good strength, and is widely applied to radiating systems of airplanes, engines and the like at present.

Along with the increase of the power of the engine, the requirement of the heat dissipation capacity is improved, and the size of the micro-channel tubular radiator is gradually increased, as shown in fig. 9, the micro-channel tubular radiator is an outline drawing of a large stainless steel or high-temperature alloy tubular radiator, the length of the micro-channel tubular radiator is increased from 50-200 mm to 800-1200 mm, and the diameter of the micro-channel tubular radiator is increased from 30-100 mm to 150-300 mm. After the volume of the radiator is increased, if the traditional brazing method of the small-sized tube array radiator is still used, a series of problems of deformation of the brazed radiator, dislocation of radiating pipes, loss of brazing filler metal and the like can occur when the large-sized tube array radiator is brazed.

Disclosure of Invention

The invention aims to provide a brazing method of a large stainless steel or high-temperature alloy tubular radiator core assembly, which solves the problems of brazing deformation, radiating pipe dislocation, brazing filler metal loss and the like in vacuum brazing of a large stainless steel or high-temperature alloy tubular radiator.

The applicant finds that the main reason for the problems is that the expansion amount generated by the temperature difference in the brazing process is inconsistent, so that the problem of dislocation of each part in the radiator core assembly is obvious (compared with a small-sized tubular radiator), and finally the problems of brazing deformation, radiating pipe dislocation, brazing filler metal loss and the like of the large-sized tubular radiator core assembly are caused.

Wherein, the influence is the biggest again with the dislocation of casing and cooling tube. Because the expansion amounts of the shell on the outer side and the radiating pipe in the shell are different, the shell on the outer side is extended in the brazing and heating process, and the core end plates at two ends are pushed to synchronously move outwards; and inboard cooling tube temperature is low, and its elongation can not keep up with the outer volume of moving of core end plate to the condition that cooling tube and core end plate misplaced appears, the cooling tube deviates from the core end plate when serious, leads to cooling tube and core end plate not brazed, follow-up some listed problems such as the whole deformation of initiation radiator, cooling tube dislocation, brazing filler metal run off.

In order to solve the problems, the invention adopts the following scheme:

a brazing method of a large tube nest radiator core component comprises the following steps,

the method comprises the following steps that firstly, a brazing structure is designed, a tube type radiator core assembly participating in brazing comprises a radiating tube, a positioning rod, a core end plate, a flow guide plate and a shell, the tube type radiator core assembly is made of stainless steel or high-temperature alloy which can avoid coarse grains during heat preservation at a temperature of 500-800 ℃, and the aperture of the flow guide plate is larger than the outer diameters of the radiating tube and the positioning rod, so that the radiating tube can be conveniently assembled;

step two, positioning welding, namely fixing the positioning rod with the core end plate and the guide plate on the first side by argon arc welding;

thirdly, penetrating a pipe, namely penetrating a radiating pipe into the core end plate on the first side and the hole corresponding to the guide plate; the first side refers to a left side or a right side of the core end plate, when the first side is determined to be the left side of the core end plate, the second side corresponds to the right side of the core end plate, and when the first side is determined to be the right side of the core end plate, the second side corresponds to the left side of the core end plate;

step four, assembling, namely assembling the assembly with the radiating pipe in the step three;

step five, tack welding, namely fixing the core end plate on the second side and the shell by argon arc welding, pushing the radiating pipe into a corresponding hole of the core end plate on the second side, and ensuring that the left end and the right end of the radiating pipe extend out of the core end plate;

step six, clamping, namely vertically fixing the tube array radiator core assembly on a brazing tool;

step seven, coating brazing filler metal, flatly placing strip-shaped brazing filler metal between the radiating pipe on the core end plate and the gap between the radiating pipes, and then diluting the brazing filler metal to enable the brazing filler metal to be uniformly spread on the brazing mirror surface;

step eight, calculating the maximum temperature difference, namely calculating the maximum temperature difference required to be controlled at each temperature point of the shell and the radiating pipe in the brazing process according to the dislocation quantity of the parts, wherein the calculation formula is that delta T is the temperature difference of the parts, delta L is the dislocation quantity of the parts, f is the expansion coefficient, and L is the length of the radiator core assembly;

step nine, entering a furnace, ensuring that the tube array radiator core assembly is vertically fixed on a brazing tool, and inserting thermocouples at different positions of the tube array radiator core assembly;

step ten, performing vacuum brazing, heating up and preserving heat in stages, presetting brazing parameters, manually controlling the heating process in the brazing process, ensuring that the temperature difference between the surface of the shell and the thermocouple in the middle of the radiating pipe is not greater than the maximum temperature difference obtained by calculation in the step eight, and recording the actual time required by the heating up and preserving heat section in each stage;

step eleven, correcting brazing parameters, and correcting preset brazing parameters according to the actual time required by each stage obtained in the step eleven to obtain actual brazing parameters.

Further, in the present invention,

in the first step, the length of the core assembly of the tube type radiator is 800-1200 mm, the diameter is 150-300 mm, the material of the core assembly of the tube type radiator is 316L or NO6600, the brazing clearance between the radiating tube, the locating rod and the core end plate is controlled to be 0.04-0.10 mm, and the aperture of the flow guide plate is 0.2-0.30 mm larger than the outer diameter of the radiating tube and the locating rod;

and in the fifth step, the radiating pipe and the locating rod extend out of the core end plate by more than 4 mm.

Further, in the seventh step, the brazing filler metal is sticky tape-shaped brazing filler metal with the grade of BNi82CrSiB and the thickness of 0.4mm, and the sticky tape-shaped brazing filler metal is cut into strips with the width of 3 mm.

And further, in the seventh step, dipping trichloroethylene by using a suction pipe to dilute the brazing filler metal, and controlling the thickness of the spread brazing filler metal to be 2-3 mm.

Further, in the sixth step and the ninth step, the brazing tool comprises a base and a support, a positioning protrusion is arranged on the base and is in plug-in connection with the core end plate, one end of the support is fixed on the base, and the other end of the support is in contact with the shell.

Further, in the ninth step, the thermocouple includes a first thermocouple, a second thermocouple and a third thermocouple, the first thermocouple is located on the surface of the middle portion of the shell, the second thermocouple is located in the middle portion of the radiating pipe, and the third thermocouple is located on the back of the core end plate.

Further, in the present invention,

in the step eight, the dislocation quantity Delta L of the part is 2 mm;

in the step ten, brazing parameters are set according to a heat preservation section at an interval of 150 ℃.

Alternatively, in the step ten, the temperature is increased and maintained in an isothermal difference mode.

Alternatively, the actual brazing parameters obtained in the step eleven are:

the first stage, pre-vacuumizing for 60 min;

in the second stage, the temperature is raised to 150 ℃ for 40 min;

the third stage, keeping the temperature at 150 ℃ for 180 min;

the fourth stage, heating to 300 deg.C for 40 min;

fifthly, keeping the temperature at 300 ℃ for 150 min;

the sixth stage, heating to 450 deg.C for 40 min;

seventh stage, heat preservation is carried out at 450 ℃ for 120 min;

in the eighth stage, the temperature is raised to 600 ℃ for 40 min;

ninth stage, heat preservation is carried out at 600 ℃ for 120 min;

in the tenth stage, the temperature is increased to 750 ℃ for 40 min;

eleventh stage, heat preservation at 750 deg.C for 120 min;

in the twelfth stage, the temperature is raised to 900 ℃ for 30 min;

thirteenth stage, heat preservation is carried out at 900 ℃ for 120 min;

in the fourteenth stage, the temperature is raised to 1040 ℃ for 30 min;

a fifteenth stage, keeping the temperature at 1040 ℃ and brazing for 20 min;

sixteenth stage, cooling to 800 ℃ for 180 min;

seventeenth stage, cooling along with the furnace.

The brazing method of the large tube array radiator core assembly also comprises the following steps,

step twelve, cooling along with the furnace, discharging the tube-type radiator core assembly from the furnace when the temperature is cooled to below 60 ℃, and taking the tube-type radiator core assembly subjected to brazing down from a brazing tool;

step thirteen, inspection: checking the appearance quality of the brazing, confirming that the heat dissipation pipe does not shrink and enter the core end plate, and ensuring that the brazing seam is full and the brazing filler metal does not run off;

fourteen steps of welding: welding the core end plates on the first side and the second side with the shell by argon arc welding;

fifteen, assessment test: and performing a sealing test, a pressure test and a blasting test on the welded shell and tube radiator core assembly.

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

(1) the brazing method is not only suitable for stainless steel materials, but also suitable for high-temperature alloys, and in the shell-and-tube radiator core assembly participating in brazing, the radiating pipe, the locating rod, the core end plate, the flow guide plate and the shell are not required to be made of materials of the same grade, and can be made of materials of different grades as long as the core assembly has the brazing characteristic, for example, the radiating pipe is made of stainless steel 316L, and the core end plate and the shell can be made of high-temperature alloy NO6600 for improving the strength;

(2) the invention introduces the idea of controlling the maximum temperature difference during the temperature rise and heat preservation of the large-size tubular radiator during the brazing, and calculates the maximum temperature difference of each temperature point through a calculation formula of delta T ═ delta L/f × L, wherein, the dislocation quantity delta L of parts is determined by the length of the radiating pipe extending out of the core end plate (the brazing filler metal is coated on the gap between the radiating pipe and the radiating pipe on the core end plate, meanwhile, the radiating pipe is extended out of the core end plate for a certain distance, during the temperature rise of the brazing, the shell temperature is higher than the temperature of the internal radiating pipe, the two core end plates are pushed to move outwards, but the moving quantity can not lead the radiating pipe to be lower than the brazing filler metal surface, otherwise, the brazing filler metal flows into the inner cavity of the radiating pipe to block the inner cavity of the radiating pipe, the radiating function is lost, and the distance of the radiating pipe extending out of the core end plate is the maximum moving quantity, for example, in the embodiment of the invention, the single surface of the radiating pipe extends out of the core end plate by 4mm, the thickness of the single surface coated with brazing filler metal is 2-3 mm, the single surface of the radiating pipe extending out of the brazing filler metal surface is only 1-2 mm, so that the dislocation quantity delta L of the core end plate and the radiating pipe is 2mm, the expansion coefficient f is taken according to the specific expansion coefficient of the material at the temperature, the length L of the radiator core assembly is a fixed design value, the invention reasonably simplifies the value of L, strictly speaking, the part dislocation quantity refers to the elongation deviation between the core end plate and the radiating pipe, so the part dislocation quantity delta L is delta L1-delta L2 (delta L1 is the displacement quantity generated by thermal expansion between the two core end plates, and delta L2 is the thermal expansion displacement quantity of the radiating pipe), at this time,

Δ L1 ═ f1 ═ T1 ═ L1(Δ L1 is the amount of displacement between the two core end plates due to thermal expansion, f1 is the case expansion coefficient, T1 is the case temperature, and L1 is the distance between the two core end plates);

Δ L2 ═ f2 × T2 × L2(Δ L2 is the thermal expansion displacement of the radiating pipe, f2 is the coefficient of expansion of the radiating pipe, T2 is the temperature of the radiating pipe, and L2 is the length of the radiating pipe);

as a result of this, the number of the,

△L＝△L1-△L2

＝f1*T1*L1-f2*T2*L2

f 1T 1L-f 2T 2L (since the 3 dimensions of the distance between the two core end plates, the length of the radiator pipe, and the length of the radiator core assembly do not differ much, so L1 and L2 are replaced by the length L of the radiator core assembly together);

if the expansion coefficients of the materials of the core end plate, the radiating pipe and the shell are similar, the same expansion coefficient is taken during calculation, and then the delta T is substituted into the delta L which is f 1T 1L-f 2T 2L, so that the maximum temperature difference calculation formula of the invention can be obtained:

△L＝f1*T1*L-f2*T2*L

＝f*T1*L-f*T2*L

＝f*(T1-T2)*L

＝f*△T*L；

(3) the maximum temperature difference calculation idea of the invention can be expanded to brazing methods of different materials, and at the moment, different expansion coefficients f1 and f2 are only required to be reserved according to the calculation formula in the step (2);

(4) the brazing method is improved from the aspects of components participating in brazing, assembly sequence among the components, assembly clamping, and presetting and correcting of brazing parameters, the problem generated when the shell and tube radiator core components are transited from small size to large size is solved, particularly, when brazing parameters are determined, the maximum temperature difference of each temperature point is calculated by adopting a calculation formula delta T-delta L/f-L, and the final brazing parameters are ensured to be practical and feasible;

(5) the method comprises the steps of presetting brazing parameters, controlling specific time of each temperature rise and heat preservation through monitoring of a thermocouple by means of the fact that the calculated temperature difference delta T of each time point cannot be larger than the calculated temperature difference delta T, then correcting the preset brazing parameters, solidifying the time parameters and the temperature parameters, locking the brazing parameters corresponding to temperature and time in a vacuum brazing furnace, and realizing programming of the brazing parameters of the large-scale tubular radiator.

The large stainless steel or high-temperature alloy tubular radiator with the length of 1200mm and the diameter of 260mm is processed by adopting the brazing method, and a series of problems of brazing deformation, radiating pipe dislocation, brazing filler metal loss and the like existing when the large stainless steel or high-temperature alloy tubular radiator is processed by adopting the existing vacuum brazing method are solved through 16.5MPa pressure test and 24MPa maximum burst test examination.

Drawings

FIG. 1 is a schematic diagram of a tube array heat sink core assembly;

FIG. 2 is a schematic view of the welding of the positioning rod;

FIG. 3 is a schematic view of a heat pipe assembly;

FIG. 4 is a schematic view of the housing assembly;

FIG. 5 is a schematic view of argon arc welding;

FIG. 6 is a schematic view of a brazing clamp;

FIG. 7 is a schematic view of braze coating;

FIG. 8 is a schematic view of a thermocouple placement location;

FIG. 9 is an outline view of a large stainless steel tubular radiator;

in the figure: 1-radiating pipe, 2-locating rod, 3-core end plate, 4-guide plate, 5-shell, 6-tube radiator core assembly, 7-brazing tool, 8-strip brazing filler metal, 9-first thermocouple, 10-second thermocouple, 11-third thermocouple.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and specific embodiments, but it should not be understood that the scope of the subject matter of the present invention is limited to the following embodiments, and various modifications, substitutions and alterations made based on the common technical knowledge and conventional means in the art without departing from the technical idea of the present invention are included in the scope of the present invention.

For the brazing of the core assembly 6 of the large (large-size) tubular radiator, the problem that the radiating pipe 1, the positioning rod 2, the core end plate 3, the flow guide plate 4 and the shell 5 are dislocated due to thermal expansion caused by inconsistent temperature in the heating process is highlighted, but the problem basically cannot occur when the small tubular radiator is brazed. Wherein, the elongation deviation of the radiating pipe 1 and the core end plate 3 (the displacement generated by the shell 5 pushing the core end plate 3) in the brazing heating process is an important factor influencing the success of brazing the large-scale tubular radiator core assembly 6.

As can be seen from the elongation deviation formula ". DELTA.L ═ f.DELTA.T.L" (. DELTA.L-part misalignment amount, f-expansion coefficient,. DELTA.T-part temperature difference, L-radiator core assembly length), the larger the radiator core assembly length L, the larger the part misalignment amount. DELTA.L. Particularly, when the length of the radiator is increased to 800-1200 mm from the traditional 50-200 mm, the maximum part dislocation delta L is increased by 24 times. Therefore, the misalignment between the radiator pipe 1 and the core end plate 2 caused by thermal expansion becomes a major problem in the brazing process of large tubular radiators, and is the most significant factor in the success of brazing.

The temperature differences at the same displacement for the small-sized shell and tube heat sink (length 150mm) and the large-sized shell and tube heat sink (length 1200mm) are compared in tables 1 and 2. As can be seen from Table 1, the conventional small-sized tubular radiator 150mm long ensures that the minimum temperature difference is 623 ℃ under the condition that the dislocation amount of the shell 5 and the radiating pipe 1 is not more than 2 mm. In the general brazing process, the temperature difference of the parts does not exceed 400 ℃. Therefore, the dislocation of the parts in the conventional small-sized shell and tube radiator does not cause the radiating pipe 1 to be lower than the level of the brazing filler metal. In the process of brazing the small tubular radiator, the problem of part dislocation can not be considered. As can be seen from Table 2, in the case of the large-sized tube type radiator with the length of 1200mm, if the dislocation amount of the parts is controlled to be not more than 2mm, the temperature difference cannot be more than 77 ℃, and the control is required. Otherwise, the offset amount of the small tubular radiator is 10mm (see table 3 in detail) according to the brazing curve of the small tubular radiator when the temperature difference is about 400 ℃, and in this case, the radiating pipe 1 is already separated from the core end plate 3.

TABLE 1 temperature difference control for stainless steel tubular radiator brazing (150)

TABLE 2 temperature difference control for stainless steel tubular radiator (1200)

TABLE 3 temperature difference control of stainless steel tubular radiator (1200)

In the embodiment, as shown in fig. 1 to 7, the length of the large-scale tubular radiator core assembly 6 is 800 to 1200mm, the diameter is 150 to 300mm, and the material of the tubular radiator core assembly 6 is selected from 316L, NO6600 stainless steel materials or high-temperature alloys which can avoid the occurrence of large crystal grains during heat preservation at 500 to 800 ℃. The shell and tube radiator core assembly 6 mainly comprises the radiating pipe 1, the core end plate 3, the guide plate 4, the shell 5 and other parts, wherein the radiating pipe 1, the core end plate 3, the guide plate 4 and the shell 5 do not need to be of the same grade, and materials of different grades can be brazed as long as the materials have the characteristic of being capable of being brazed. For example, the heat pipe 1 is made of stainless steel 316L, and the core end plate 3 and the shell 5 can be made of high temperature alloy NO6600 to improve the strength of the product.

The brazing method of the large-scale tubular radiator mainly comprises the aspects of brazing structures, brazing filler metal coating, brazing tools, brazing parameters and the like, and specifically comprises the following steps:

in the aspect of brazing structure design: the brazing gap between the radiating pipe 1 and the core end plate 3 is controlled to be 0.04-0.10 mm, the distance from the radiating pipe 1 to the core end plate 3 is controlled to be more than 4mm, and the aperture of the flow guide plate 4 is 0.20-0.30 mm larger than that of the radiating pipe 1 and the positioning rod 2, so that the radiating pipe 1 can be conveniently assembled; it is to be noted that the length of the tubular radiator core assembly 6 is approximately equal to the distance between the core end plates 3 on both sides (corresponding to the distance from the left end to the right end in fig. 5). The diameter of the shell-and-tube radiator core assembly 6 refers to the outer diameter of the housing 5 (corresponding to the distance from the upper end to the lower end in fig. 5).

Coating the brazing filler metal: the brazing filler metal is sticky tape-shaped brazing filler metal with the grade of BNi82CrSiB and the thickness of 0.4 mm. Cutting the brazing filler metal into strip-shaped brazing filler metal strips 8 with the width of 3mm, flatly placing the brazing filler metal strips 8 between gaps between the radiating pipe 1 and the radiating pipe 1 on the core end plate 3, dipping trichloroethylene into a suction pipe to dilute the brazing filler metal, repeating the operation for many times to uniformly spread the brazing filler metal on a brazing mirror surface (when the brazing filler metal is coated on the surface of the core end plate 3 for brazing, a part of the brazing filler metal is adsorbed between corresponding holes of the radiating pipe 1 and the core end plate 3 under the capillary action, and the radiating pipe 1 and the core end plate 3 are welded into a whole, the rest of the brazing filler metal is remelted on the surface of the core end plate 3, when brazing parameters are reasonable, the surface of the layer is smooth like a mirror surface and called as a brazing mirror surface), controlling the thickness after spreading of the brazing filler metal to be 2-3 mm, and turning around the brazing filler metal at the other end of the tubulation radiator core assembly 6 according to the same method;

designing a brazing tool: designing a brazing tool 7, enabling the tube-type radiator to be vertically placed, and fixing the radiator on the brazing tool 7, wherein the brazing tool 7 comprises a base and a support, a positioning bulge is arranged on the base, the positioning bulge is inserted into the core end plate 3 to play a positioning role, so that the radiator is vertically placed, one ends of a plurality of supports are fixed on the base, and the other ends of the supports are in contact with the shell 5, so that the stability of the radiator is kept;

brazing parameters are as follows: in the brazing temperature rise stage, the parts (the heat pipe 1, the core end plate 3 and the shell 5) expand along with the rise of the temperature, namely, the parts stretch. The heat transfer process of vacuum brazing is mostly radiation, the shell 5 is located at the outer surface, the radiating pipe 1 is located at the inner part, the heat is radiated to the inner radiating pipe 1 by one layer of the shell 5 at the outer side, and the inner radiating pipe 1 and the shell 5 at the outer side have great temperature difference (the closer to the radiating pipe 1 in the middle, the greater the temperature difference). This difference in temperature can lead to on same time point, the elongation of the casing 5 in the outside is greater than the elongation of cooling tube 1, and in the severe case, cooling tube 1 can deviate from core end plate 3, leads to cooling tube 1 and core end 3 board not to braze.

Through exploration, aiming at a stainless steel tubular radiator with the length of 800-1200 mm and the diameter of 150-300 mm, at the same time point, the extension deviation of the shell 5 and the radiating pipe 1 caused by inconsistent temperature, namely the part dislocation quantity delta L is most suitable for controlling according to 2mm, and the part temperature difference delta T of each heating and heat preservation section is controlled according to a formula (1):

Δ T ═ Δ L/(f × L) formula (1);

wherein: delta T-part temperature difference; DeltaL-part misalignment amount; f-coefficient of expansion; l-tubulation core assembly length; wherein Δ L is controlled at 2 mm.

Inputting the data into a formula (1), calculating the maximum temperature difference required to be controlled in the brazing process between the shell 5 at the outer side and the radiating pipe 1 in the shell, and obtaining the temperature difference delta T between the inner part and the outer part of the shell-and-tube radiator core assembly 6 with the length of 800-1200 mm when brazing.

In combination with the size and heating condition of the furnace body of the vacuum brazing furnace, 1 radiator is selected as a test piece, thermocouples (shown in figure 8) are inserted into the surface of the shell 5, the middle part of the radiating pipe 1 and the back surface of the core end plate 3, and brazing parameters are set according to a heat preservation section at 150 ℃. In the brazing process, the heating process is manually controlled, and the temperature difference between the surface of the shell 5 and the thermocouple in the middle of the radiating pipe 1 is not more than 120 ℃, so that the required heat preservation time of each section is actually obtained. And correcting the brazing parameters according to the actual heat preservation time to obtain the brazing parameters shown in the table 4. The brazing parameter can be used for vacuum brazing of the shell and tube radiator core component with the length of 800-1200 mm and the diameter of 150-300 mm.

TABLE 4 brazing parameters

Phases	Require that	Reference time	Phases	Require that	Reference time
						A	Pre-evacuation of vacuum	60min	K	Heat preservation at 750 deg.C	120min
B	Heating to 150 deg.C	40min	L	Heating to 900 deg.C	30min
						C	Keeping the temperature at 150 DEG C	180min	M	900 ℃ of heat preservationTemperature of	120min
D	Heating to 300 deg.C	40min	N	Heating to 1040 deg.C	30min
						E	300 ℃ heat preservation	150min	O	Heat preservation at 1040 deg.C	Brazing for 20min
F	Heating to 450 deg.C	40min	P	Cooling to 800 deg.C	180min
						G	Keeping the temperature at 450 DEG C	120min	Q	Furnace cooling	/
H	Heating to 600 deg.C	40min
						I	Keeping the temperature at 600 DEG C	120min
J	Heating to 750 deg.C	40min

Note: in Table 4, the reference time refers to the time taken for the temperature to rise to a predetermined temperature in the temperature rising stage and the time taken for the temperature to rise in the temperature maintaining stage.

According to the above brazing parameters, it is determined that the radiating pipe 1 does not come off the core end plate 3 after brazing of the tube type radiator core assembly 6 when the displacement amount of the radiating pipe 1 and the core end plate 3 is not more than 2mm during brazing.

The coating thickness of brazing filler metal is controlled to be 2-3 mm when a large-scale shell and tube radiator is brazed, and the shell and tube radiator core assembly 6 is vertically placed when the shell and tube radiator is brazed, so that the brazing filler metal can be prevented from losing, and the brazing seam formed by the radiating pipe 1 and the core end plate 3 is full.

The formula of temperature difference control ". DELTA.T. -. DELTA.L/(f. xL)" can calculate the temperature difference to be controlled between the outer shell 5 and the inner radiating pipe 1 when the shell-and-tube radiator core assembly 6 of different materials and different lengths is vacuum-brazed.

As a recommended brazing parameter, the specific brazing parameter of the stainless steel tubular radiator with the length of 800-1200 mm and the diameter of 150-300 mm is shown in Table 4.

The following illustrates the method of carrying out the invention by way of a specific example:

as shown in FIGS. 1 to 8, the length of the stainless steel large-scale tubular radiator in this example is 1200mm, the diameter is 260mm, and the material is 316L. The vacuum brazing is implemented as follows:

1) brazing structure design: the distance between the left core end plate 3 and the right core end plate 3 is 1200mm, the diameter of the shell 5 is 260mm, the lengths of the radiating pipe 1 and the positioning rod 2 are 1208mm, and the specification of the radiating pipe 1 is as follows

The core end plate 3 has a bore diameter of

Aperture of the deflector 4

All the materials mentioned above are 316L, as shown in table 5:

TABLE 5 core assembly composition of large stainless steel tube array radiator

Serial number	Name of part	Number of	Material	Remarks for note
					1	Radiating pipe	3178	316L	/
2	Distance rod	6	316L	/
					3	Core end plate	2	316L	/
4	Flow guide plate	7	316L	/
					5	Shell body	1	316L	/

2) Positioning welding: as shown in fig. 2, the positioning rod 2 is fixed with the core end plate 3 and the guide plate 4 on the left side by argon arc welding;

3) pipe penetration: as shown in fig. 3, the radiating pipe 1 is assembled to the module shown in fig. 2;

4) assembling: as shown in fig. 4, the assembly of fig. 3 with the radiating pipe 1 inserted is assembled into the housing 5;

5) positioning welding: as shown in fig. 5, after the core end plate 3 on the right side and the shell 5 are fixed by argon arc welding, the radiating pipe 1 is pushed into the core end plate 3 on the right side, and the distance that the left end and the right end of the radiating pipe 1 respectively extend out of the core end plate 3 is ensured to be 4 mm;

6) clamping: as shown in fig. 6, the shell and tube radiator core assembly 6 is vertically fixed on the brazing tool 7;

7) coating solder: as shown in fig. 7, a 0.4mm thick adhesive tape is cut into 3mm wide strips of solder 8, and then placed on the brazing mirror formed by the radiating pipe 1 and the core end plate 3, and then diluted by dipping the suction pipe in trichloroethylene, so that the solder is uniformly spread on the brazing mirror. Repeating the operation for 2-3 times to ensure that the thickness of the spread brazing filler metal is 2-3 mm, and after the brazing filler metal is solidified, turning around and coating the brazing filler metal of the core end plate 3 at the other end according to the same method;

8) maximum temperature difference calculation: calculating the maximum temperature difference between the outer shell 5 and the inner radiating pipe 1 to be controlled in the brazing process according to a formula (1) ' delta T ═ delta L/(f ═ L ' (delta L ═ 2mm) ');

9) entering a furnace: as shown in fig. 8, the radiator core assembly is vertically fixed on the brazing tool 7, thermocouples are inserted into the surface of the shell 5, the middle of the radiating pipe 1 and the back of the core end plate 3, the first thermocouple 9 is located on the surface of the middle of the shell 5, the second thermocouple 10 is located in the middle of the radiating pipe 1, the third thermocouple 11 is located on the back of the core end plate 3, the thermocouples are used as measuring points for measuring temperature difference, usually according to practical engineering experience, the highest temperature part and the lowest temperature part during brazing are pre-determined, and then heat thermocouples are released at the two parts for measurement, in this embodiment, the highest temperature and the lowest temperature are determined by three temperature measuring points;

10) vacuum brazing: the brazing parameters were set at 150 ℃ for one hold section. In the brazing process, the heating process is manually controlled, the temperature difference between the surface of the shell 5 and a thermocouple in the middle of the radiating pipe 1 is not more than 120 ℃, and the actual time required by each section of heating and heat preservation is recorded;

11) and (3) correcting brazing parameters: and (5) obtaining the actually required time of each stage according to the step 10, and correcting the brazing parameters to obtain the brazing parameters shown in the table 1. The brazing parameter can be used for vacuum brazing of the shell and tube radiator core component with the length of 800-1200 mm and the diameter of 150-300 mm. (when welding products with similar structures, the brazing parameters can be directly input in the step 8, and then the

steps

10 and 11 are omitted);

12) discharging: cooling to below 60 ℃ along with the furnace, discharging, and taking down the stainless steel tube type radiator core assembly 6 after brazing from the brazing tool 7;

13) and (4) checking: visual inspection of the appearance quality of brazing is carried out, the heat dissipation pipe does not shrink into the core end plate 3, the brazing seam is full, and the brazing filler metal is not lost;

14) welding: welding the core end plates 3 on the left side and the right side with the shell 5 by argon arc welding;

15) and (3) assessment test: and (3) carrying out 16.5MPa of tightness test, 24MPa of blasting test and other examinations on the welded shell and tube radiator core assembly 6.

The above embodiments are not intended to limit the scope of the present invention, and any variations, modifications, or equivalent substitutions made on the technical solutions of the present invention should fall within the scope of the present invention.

Claims

1. A brazing method of a large tube nest radiator core component is characterized in that: comprises the steps of (a) preparing a mixture of a plurality of raw materials,

the method comprises the following steps that firstly, a brazing structure is designed, a tube type radiator core assembly (6) participating in brazing comprises a radiating tube (1), a positioning rod (2), a core end plate (3), a guide plate (4) and a shell (5), the tube type radiator core assembly (6) is made of stainless steel or high-temperature alloy capable of avoiding coarse grains during heat preservation at a temperature of 500-800 ℃, and the aperture of the guide plate (4) is larger than the outer diameters of the radiating tube (1) and the positioning rod (2);

secondly, positioning welding, namely fixing the positioning rod (2) with the core end plate (3) and the guide plate (4) on the first side by argon arc welding;

thirdly, penetrating a pipe, namely penetrating the radiating pipe (1) into corresponding holes of the core end plate (3) and the guide plate (4) on the first side;

step four, assembling, namely assembling the assembly penetrating the radiating pipe (1) in the step three into the shell (5);

fifthly, positioning welding, namely fixing the core end plate (3) on the second side and the shell (5) by argon arc welding, pushing the radiating pipe (1) into a corresponding hole of the core end plate (3) on the second side, and ensuring that the left end and the right end of the radiating pipe (1) extend out of the core end plate (3);

step six, clamping, namely vertically fixing the tube array radiator core assembly (6) on a brazing tool (7);

step seven, coating brazing filler metal, flatly placing strip-shaped brazing filler metal between the radiating pipe (1) on the core end plate (3) and the gap between the radiating pipe (1), and then diluting the brazing filler metal to uniformly spread the brazing filler metal on a brazing mirror surface;

step eight, calculating the maximum temperature difference, namely calculating the maximum temperature difference required to be controlled at each temperature point of the shell (5) and the radiating pipe (1) in the brazing process according to the dislocation quantity of the parts, wherein the calculation formula is that delta T is delta L/(f L), the delta T is the temperature difference of the parts, the delta L is the dislocation quantity of the parts, f is the expansion coefficient, and L is the length of the radiator core assembly;

step nine, entering a furnace, ensuring that the tube array radiator core assembly (6) is vertically fixed on the brazing tool (7), and inserting thermocouples at different positions of the tube array radiator core assembly (6);

step ten, performing vacuum brazing, heating up and preserving heat in stages, presetting brazing parameters, manually controlling the heating process in the brazing process, ensuring that the temperature difference between the surface of the shell (5) and the thermocouple in the middle of the radiating pipe (1) is not greater than the maximum temperature difference obtained by calculation in the step eight, and recording the actual time required by the heating up and preserving heat section in each stage;

2. The brazing method of a large tubulation radiator core assembly according to claim 1, wherein:

in the first step, the length of a tube array type radiator core assembly (6) is 800-1200 mm, the diameter is 150-300 mm, the material of the tube array type radiator core assembly (6) is 316L or NO6600, the brazing clearance between a radiating tube (1), a positioning rod (2) and a core end plate (3) is controlled to be 0.04-0.10 mm, and the aperture of a guide plate (4) is 0.2-0.30 mm larger than the outer diameters of the radiating tube (1) and the positioning rod (2);

in the fifth step, the radiating pipe (1) and the locating rod (2) extend out of the core end plate (3) for more than 4 mm.

3. The brazing method of a large tubulation radiator core assembly according to claim 1, wherein: in the seventh step, the brazing filler metal is sticky tape-shaped brazing filler metal with the grade of BNi82CrSiB and the thickness of 0.4mm, and the sticky tape-shaped brazing filler metal is cut into strips with the width of 3 mm.

4. The brazing method for the large-scale tubular radiator core component according to claim 1, characterized in that: and seventhly, dipping trichloroethylene by using a suction pipe to dilute the brazing filler metal, and controlling the thickness of the spread brazing filler metal to be 2-3 mm.

5. The brazing method of a large tubulation radiator core assembly according to claim 1, wherein: in the sixth step and the ninth step, the brazing tool (7) comprises a base and a support, a positioning protrusion is arranged on the base and is connected with the core end plate (3) in an inserting mode, one end of the support is fixed on the base, and the other end of the support is in contact with the shell (5).

6. The brazing method for the large-scale tubular radiator core component according to claim 1, characterized in that: in the ninth step, the thermocouples comprise a first thermocouple (9), a second thermocouple (10) and a third thermocouple (11), the first thermocouple (9) is located on the surface of the middle of the shell (5), the second thermocouple (10) is located in the middle of the radiating pipe (1), and the third thermocouple (11) is located on the back of the core end plate (3).

7. The brazing method of a large tubulation radiator core assembly according to claim 1, wherein:

in the step eight, the dislocation quantity Delta L of the part is 2 mm;

8. The brazing method of a large tubulation radiator core assembly according to claim 1, wherein: and step ten, heating and preserving heat according to an isothermal difference mode.

9. The brazing method of a large tubulation radiator core assembly according to claim 1, wherein: the actual brazing parameters obtained in the eleventh step are as follows:

the first stage, pre-vacuumizing for 60 min;

in the second stage, the temperature is raised to 150 ℃ for 40 min;

the third stage, keeping the temperature at 150 ℃ for 180 min;

the fourth stage, heating to 300 ℃ for 40 min;

fifthly, keeping the temperature at 300 ℃ for 150 min;

the sixth stage, heating to 450 deg.C for 40 min;

seventh stage, heat preservation is carried out at 450 ℃ for 120 min;

in the eighth stage, the temperature is raised to 600 ℃ for 40 min;

ninth stage, heat preservation is carried out at 600 ℃ for 120 min;

in the tenth stage, the temperature is raised to 750 ℃ for 40 min;

eleventh stage, heat preservation is carried out at 750 ℃ for 120 min;

in the twelfth stage, the temperature is raised to 900 ℃ for 30 min;

thirteenth stage, heat preservation is carried out at 900 ℃ for 120 min;

in the fourteenth stage, the temperature is raised to 1040 ℃ for 30 min;

a fifteenth stage, keeping the temperature at 1040 ℃ and brazing for 20 min;

sixteenth stage, cooling to 800 ℃ for 180 min;

seventeenth stage, cooling along with the furnace.

10. The brazing method of a large tubulation radiator core assembly according to claim 1, wherein: also comprises the following steps of (1) preparing,

step twelve, cooling along with the furnace, discharging the tube-type radiator core assembly (6) after brazing from the brazing tool (7) after cooling along with the furnace to below 60 ℃;

step thirteen, inspection: checking the appearance quality of brazing, confirming that the heat dissipation pipe (1) does not shrink and enter the core end plate (3), and ensuring that the brazing seam is full and the brazing filler metal does not run off;

fourteen steps of welding: welding the core end plates (3) on the first side and the second side with the shell (5) by argon arc welding;

fifteen, assessment test: and (3) carrying out a sealing test, a pressure test and a blasting test on the welded shell and tube radiator core assembly (6).