Silver powder sintering jig, sintering method and dilution refrigeration mixing chamber heat exchanger

Abstract

The invention relates to the technical field of dilution refrigeration equipment, and provides a silver powder sintering jig which comprises a module provided with a plurality of injection holes; the cover plate is fixedly provided with a plurality of material pressing columns which are the same as the material injection holes in number and correspond to the material injection holes in distribution position. The cold guide disc is fixedly provided with a plurality of core columns which are the same as the material injection holes in number and correspond to the material injection holes in distribution position; the core column of the cold guide disc is inserted from one end of the injection hole, and the pressing column of the cover plate is inserted from the other end of the injection hole; and a filling space for filling silver powder is formed among the core column, the inner wall of the injection hole and the end face of the pressing column. Therefore, the silver powder is distributed outside the side face and the end face of the core column, the sintering layers are formed on the side face and the end face of the core column at the same time after sintering, and the silver powder layer is sintered on the surface of the columnar structure of the heat exchanger. The invention further provides a sintering method and the dilution refrigeration mixing chamber heat exchanger, the multiple heat exchange columns are arranged, the overall specific surface area is increased, the heat exchanger has the huge heat exchange area, and heat resistance can be effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of dilution refrigeration equipment, and in particular relates to a silver powder sintering fixture, a sintering method and a dilution refrigeration mixing chamber heat exchanger. Background Art

[0002] For ultra-low temperature equipment, such as the heat exchanger of a dilution refrigerator, the fluid inside is under ultra-low temperature conditions. At this time, the thermal resistance between the liquid and solid surfaces becomes very large, which leads to poor convective heat transfer. The mixing chamber is the lowest temperature structure in the dilution refrigeration system, with the lowest temperature being below 10mK. In order to overcome the Kapitza thermal resistance at extremely low temperatures, the mixing chamber is required to have a huge heat exchange area.

[0003] At present, the mainstream dilution refrigerator mainly uses silver pancake heat exchangers, but the specific surface area is low, resulting in limited heat exchange area and unable to effectively reduce thermal resistance. If other structures with larger specific surface area are used, such as columnar structures, the existing sintering jigs cannot sinter the silver powder layer on the surface of the columnar structure, making it impossible to manufacture heat exchangers with huge heat exchange areas.

[0004] In summary, the prior art obviously has inconveniences and defects in practical use, so it is necessary to improve it. Summary of the invention

[0005] In view of the above-mentioned defects, the present invention mainly provides a silver powder sintering jig to solve the technical problem of sintering and forming the silver powder layer on the surface of the columnar structure of the heat exchanger.

[0006] In order to solve the above problems, the present invention provides a silver powder sintering jig, comprising:

[0007] The module is provided with a plurality of injection holes;

[0008] The cover plate is fixed with a plurality of pressing columns which are the same in number as the injection holes and whose distribution positions correspond to the injection holes;

[0009] The cooling plate is provided with a plurality of core columns having the same number as the injection holes and corresponding distribution positions;

[0010] The core column of the cold conduction plate is inserted from one end of the injection hole, and the pressing column of the cover plate is inserted from the other end of the injection hole; a filling space for filling silver powder is formed between the core column, the inner wall of the injection hole and the end surface of the pressing column.

[0011] According to the silver powder sintering jig of the present invention, positioning areas are provided on the two end faces of the module, the cover plate and the cooling plate.

[0012] According to the silver powder sintering jig of the present invention, the positioning area on the module is formed by not opening an injection hole in a predetermined area; the cover plate and the cold plate are also not provided with a pressing column and a core column in the corresponding areas, respectively, to form respective positioning areas.

[0013] According to the silver powder sintering jig of the present invention, a gasket is further provided between the cover plate and the module.

[0014] According to the silver powder sintering jig of the present invention, the gasket is a polytetrafluoroethylene gasket.

[0015] According to the silver powder sintering jig of the present invention, the module, the cover plate and the cooling plate are all cylindrical structures.

[0016] According to the silver powder sintering jig of the present invention, a connecting plate is fixedly arranged on the outer wall of the module; and a plurality of bolt holes are evenly arranged on the cooling plate, the connecting plate and the cover plate.

[0017] A sintering method based on the silver powder sintering fixture comprises the following steps:

[0018] S1, place the cooling plate flat with the core column facing vertically upwards;

[0019] S2, assembling the module so that each stem is inserted into the corresponding injection hole;

[0020] S3, filling the injection hole with silver powder until the silver powder is flush with the upper opening of the injection hole;

[0021] S4, assembling the cover plate and applying a pressing force to the cover plate, pressing each pressing column into the corresponding injection hole to compact the silver powder in the injection hole;

[0022] S5, inserting fastening bolts through the bolt holes on the same straight line of the cooling plate, the connecting plate and the cover plate to fix the fixture;

[0023] S6, performing a sintering operation to form a sintered layer of silver powder on the surface of the core column.

[0024] According to the sintering method of the present invention, after the pressing column is pressed into the corresponding injection hole, the cover plate is removed to detect whether the silver powder thickness on the end face of the core column reaches a preset value; if it does not reach the preset value, silver powder is added and step S4 is repeated until the silver powder thickness reaches a qualified value.

[0025] A dilution refrigeration mixing chamber heat exchanger comprises a cooling plate on which a plurality of heat exchange columns are fixed; the heat exchange columns comprise a core column fixed on the cooling plate; the side and end faces of the core column are both provided with a sintering layer formed by the sintering method.

[0026] In summary, the silver powder sintering jig of the present invention distributes the silver powder on the side and end surfaces of the core column, and after sintering, a sintered layer is simultaneously formed on the side and end surfaces of the core column, thereby sintering a silver powder layer on the surface of the columnar structure of the heat exchanger. The present invention also provides a sintering method and a dilution refrigeration mixing chamber heat exchanger, which has multiple heat exchange columns, increases the overall specific surface area, and enables the heat exchanger to have a huge heat exchange area, which can effectively reduce thermal resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the explosion structure of the silver powder sintering jig of the present invention;

[0028] Figure 2 It is a schematic diagram of the combined state structure of the sintering fixture;

[0029] Figure 3 It is a schematic diagram of the combined state structure of the sintering fixture;

[0030] Figure 4 It is a cross-sectional structural schematic diagram of a dilution refrigeration mixing chamber heat exchanger of the present invention;

[0031] Figure 5 It is a structural schematic diagram of the dilution refrigeration mixing chamber heat exchanger of the present invention;

[0032] In the figure: 1-module, 11-connecting plate, 12-inner limiting ring surface, 13-injection hole; 2-cover plate, 21-pressing column, 22-gasket; 3-cooling plate, 31-core column, 32-sintering layer, 33-heat exchange column, 34-outer limiting ring surface; 4-positioning area, 41-bolt hole, 42-fastening bolt; 5-silver powder. DETAILED DESCRIPTION

[0033] See also Figure 1 The present invention provides a silver powder sintering jig, comprising:

[0034] Module 1 is provided with a plurality of injection holes 13;

[0035] The cover plate 2 is fixed with a plurality of pressing columns 21, the number of which is the same as the number of the injection holes 13 and the distribution positions are corresponding to each other;

[0036] The cooling plate 3 is provided with a plurality of core columns 31 which are the same in number and corresponding in distribution position as the injection holes 13;

[0037] Combination Figure 3 The core column 31 of the cold conduction plate 3 is inserted from one end of the injection hole 13, and the pressing column 21 of the cover plate 2 is inserted from the other end of the injection hole 13; a filling space for filling the silver powder 5 is formed between the core column 31 and the inner wall of the injection hole 13 and the end surface of the pressing column 21;

[0038] The cross-sectional shapes of the core column 31 , the injection hole 13 and the pressing column 21 are adapted to each other.

[0039] Recombination Figure 4 After sintering, a sintered layer 32 can be formed simultaneously on the side and end surfaces of the core column 31 .

[0040] Furthermore, after the core column 31 is inserted into the injection hole 13, the central axes of the two coincide with each other, so that the gap between the outer side surface of the core column 31 and the inner wall of the injection hole 13 is the same, so that the formed sintered layer 32 is uniform.

[0041] After the sintering jig of the present invention is assembled, the silver powder 5 is distributed on the side and end surfaces of the core column 31, and after sintering, a sintered layer 32 is simultaneously formed on the side and end surfaces of the core column 31. The silver powder layer is sintered on the surface of the columnar structure of the heat exchanger.

[0042] As an embodiment, a connection plate 11 is fixed on the outer wall of the module 1; a plurality of bolt holes 41 are evenly arranged on the cold plate 3, the connection plate 11 and the cover plate 2; Figure 3 After the fixture is assembled, the bolt holes 41 on the cooling plate 3, the connecting plate 11 and the cover plate 2, which are located on the same straight line, can be connected with the fastening bolts 42 to fix the fixture to prevent the silver powder from leaking.

[0043] As an embodiment, the module 1, the cover plate 2 and the cold plate 3 are all cylindrical structures.

[0044] In order to facilitate the operator to accurately insert all the core columns 31 and the pressing column 21 into the corresponding injection holes 13. Further, the two end faces of the module 1, the cover plate 2 and the cold plate 3 are provided with positioning areas 4; during assembly, the operator can quickly and accurately complete the plug-in operation by aligning the positioning areas 4.

[0045] As an embodiment, the positioning area 4 of the present invention can be formed by not providing the injection hole 13 in the predetermined area of ​​the module 1; the cover plate 2 and the cold plate 3 also do not provide the pressing column 21 and the core column 31 in the corresponding areas, respectively, to form their respective positioning areas 4;

[0046] As an example, see Figure 5 The cold conduction plate 3 is convex to form an outer limiting annular surface 34, and the module 1 is concave to form an inner limiting annular surface 12 that fits closely with the outer limiting annular surface 34; after the core column 31 is inserted into the injection hole 13, the outer limiting annular surface 34 fits closely with the inner limiting annular surface 12 to improve the sealing performance of the joint surface between the two.

[0047] As an embodiment, a gasket 22 is further provided between the cover plate 2 and the module 1 to improve the sealing performance of the cooperation between the two.

[0048] Furthermore, the gasket 22 is a polytetrafluoroethylene gasket, which has a certain elasticity and can absorb the thermal expansion of the silver powder 5 during sintering to maintain the overall stability of the fixture.

[0049] The core column 31 of the present invention is preferably a cylindrical structure, and may also be a polyhedral structure, such as a triangular prism, a quadrangular prism, a pentagonal prism, a hexagonal prism, and the like.

[0050] The present invention also provides a sintering method based on the sintering jig, comprising the following steps:

[0051] S1, see Figure 2 , place the cooling plate 3 horizontally, with the core column 31 facing vertically upwards;

[0052] S2, assembling the module 1, so that each stem 31 is inserted into the corresponding injection hole 13;

[0053] S3, filling the silver powder 5 into the injection hole 13; the silver powder 5 is filled until it is flush with the upper opening of the injection hole 13;

[0054] S4, see Figure 3 , assemble the cover plate 2, and apply a pressing force to the cover plate 2, so that each pressing column 21 is pressed into the corresponding injection hole 13; so that the silver powder 5 in the injection hole 13 is compacted.

[0055] As an embodiment, after the pressing column 21 is pressed into the corresponding injection hole 13, the cover plate 2 is removed to detect whether the thickness of the silver powder 5 on the end face of the core column 31 reaches a preset value; if it does not reach the preset value, the silver powder 5 is supplemented and step S4 is repeated until the thickness of the silver powder 5 is qualified.

[0056] S5, insert the fastening bolts 42 through the bolt holes 41 on the cooling plate 3, the connecting plate 11 and the cover plate 2 that are located in the same straight line to fix the fixture;

[0057] S6, see Figure 4 , sending the fixed fixture into a sintering device for sintering, so that the silver powder 5 forms a sintered layer 32 on the surface of the core column 31;

[0058] The sintering method of the present invention is easy to operate and can form a sintered layer 32 on the surface of the core column 31 .

[0059] See also Figure 5 The present invention also provides a dilution refrigeration mixing chamber heat exchanger, comprising a cooling plate 3, on which a plurality of heat exchange columns 33 are fixed; see Figure 4 The heat exchange column 33 includes a core column 31 fixed on the cold plate 3; the side surface and end surface of the core column 31 are provided with a sintered layer 32 formed by the sintering method.

[0060] The heat exchanger of the present invention has a plurality of heat exchange columns 33, which increases the overall specific surface area, so that the heat exchanger has a huge heat exchange area and can effectively reduce thermal resistance.

[0061] The heat exchanger uses the jig of the present invention to form the sintered layer 32, so the cold plate 3 and the core column 31 can be an integrally formed structure, which improves the thermal conductivity of the heat exchanger. At the same time, the sintered layer 32 on the side and end surface of the core column 31 is formed at one time, which further improves the thermal conductivity.

[0062] In summary, the present invention provides a silver powder sintering jig, which distributes the silver powder on the side and end of the core column, and forms a sintered layer on the side and end of the core column after sintering, thereby realizing sintering the silver powder layer on the surface of the columnar structure of the heat exchanger. The present invention also provides a sintering method and a dilution refrigeration mixing chamber heat exchanger, which has multiple heat exchange columns, increases the overall specific surface area, and makes the heat exchanger have a huge heat exchange area, which can effectively reduce thermal resistance.

[0063] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A silver powder sintering fixture, characterized in that: include: The module is provided with a plurality of injection holes; The cover plate is fixed with a plurality of pressing columns which are equal in number to the injection holes and whose distribution positions correspond to the injection holes; The cooling plate is provided with a plurality of core columns having the same number as the injection holes and corresponding distribution positions; The core column of the cold conduction plate is inserted from one end of the injection hole, and the pressing column of the cover plate is inserted from the other end of the injection hole; a filling space for filling silver powder is formed between the core column, the inner wall of the injection hole and the end surface of the pressing column.

2. The silver powder sintering jig according to claim 1, characterized in that: Positioning areas are arranged on the two end faces, the cover plate and the cold conduction plate of the module.

3. The silver powder sintering jig according to claim 2, characterized in that: The positioning area on the module is formed by not providing an injection hole in a predetermined area; the cover plate and the cold guide plate are also not provided with a pressing column and a core column in the corresponding areas, so as to form respective positioning areas.

4. The silver powder sintering jig according to claim 1, characterized in that: A gasket is also provided between the cover plate and the module.

5. The silver powder sintering jig according to claim 4, characterized in that: The gasket is a polytetrafluoroethylene gasket.

6. The silver powder sintering jig according to claim 1, characterized in that: The module, cover plate and cold plate are all cylindrical structures.

7. The silver powder sintering jig according to any one of claims 1 to 6, characterized in that: A connecting plate is fixedly arranged on the outer wall of the module; and a plurality of bolt holes are evenly arranged on the cooling plate, the connecting plate and the cover plate.

8. A sintering method based on the silver powder sintering fixture according to claim 7, characterized in that: The steps include: S1, place the cooling plate flat with the core column facing vertically upwards; S2, assembling the module so that each stem is inserted into the corresponding injection hole; S3, filling the injection hole with silver powder until the silver powder is flush with the upper opening of the injection hole; S4, assembling the cover plate and applying a pressing force to the cover plate, so that each pressing column is pressed into the corresponding injection hole to compact the silver powder in the injection hole; S5, inserting fastening bolts through the bolt holes on the same straight line of the cooling plate, the connecting plate and the cover plate to fix the fixture; S6, performing a sintering operation to form a sintered layer of silver powder on the surface of the core column.

9. The sintering method according to claim 8, characterized in that: After the pressing column is pressed into the corresponding injection hole, the cover plate is removed to detect whether the silver powder thickness on the end face of the core column reaches a preset value; if it does not reach the preset value, silver powder is added and step S4 is repeated until the silver powder thickness reaches a qualified value.

10. A dilution refrigeration mixing chamber heat exchanger, characterized in that: It comprises a cooling plate on which a plurality of heat exchange columns are fixed; the heat exchange columns comprise a core column fixed on the cooling plate; the side and end faces of the core column are provided with a sintering layer formed by the sintering method as claimed in claim 8 or 9.

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