High-vacuum high-pressure vertical brazing furnace with external circulation cooling metal screen

Abstract

The utility model relates to the field of heat treatment equipment. A metal electric heating element and at least two layers of metal reflecting screens are arranged in a furnace body, a vacuum system and an external water cooling system are further integrated in the furnace body, and the furnace body is further provided with a high-pressure air inlet for introducing high-pressure gas. A plurality of layers of metal reflecting screens are adopted in the hot area of the brazing furnace, so that the cleanliness of the hot area can be guaranteed while effective heat preservation and material cost reduction are achieved; a metal heating element is adopted, so that the cleanliness is kept on the premise of ensuring the uniformity of the temperature in the furnace; the vacuum system adopts two roots vacuum pumps, so that the exhaust capacity and the exhaust speed are increased, the exhaust time is shortened, and the working efficiency of the vacuum system is improved; the external water-cooling system solves the problem of overheating deformation through the water-cooling interlayer, the working efficiency of the brazing furnace is improved, the heat exchanger is convenient to clean and maintain, and the side water-cooling system is favorable for reducing the total height of equipment and is convenient to install in a plant with insufficient floor height.

Description

Technical Field

[0001] The utility model relates to the field of heat treatment equipment, in particular to a brazing furnace. Background Art

[0002] The heating chamber of the brazing furnace needs to be insulated. Currently, most brazing furnaces use graphite felt, ceramic felt, mineral wool, etc., relying on the high temperature resistance and low thermal conductivity of the material itself to achieve thermal insulation, limit the heat within a certain range, and reduce heat loss and temperature rise outside the heating screen.

[0003] However, with the continuous upgrading of domestic industrial industries, the aerospace industry has increasingly higher requirements for the cleanliness of equipment, and the above-mentioned thermal insulation materials cannot meet the requirements of the aerospace industry in terms of cleanliness.

[0004] In addition, industrial upgrading has also put forward new requirements for the multifunctional integration of equipment, such as the requirement to achieve higher vacuum degrees, cleaner quenching methods, and the ability to adapt to factories with limited floor heights. Utility Model Content

[0005] The utility model aims to provide an external circulation cooling metal screen high vacuum high pressure vertical brazing furnace to solve the above technical problems.

[0006] The technical problem solved by the present invention can be achieved by adopting the following technical solutions:

[0007] The external circulation cooling metal screen high vacuum high pressure vertical brazing furnace comprises an installation platform and a furnace body. The furnace body is also provided with an electric heating system and a heat insulation area. The installation platform is a double-layer platform supported by columns. The furnace body comprises a furnace shell, a head and a furnace bottom. The upper end of the furnace shell is fixedly connected to the head, and the lower end of the furnace shell is detachably connected to the furnace bottom. The furnace body is arranged on the upper layer of the platform through a mounting frame on the outer wall of the furnace shell. The heat insulation area of ​​the furnace body adopts at least two layers of metal reflective screens, the inner layer of the metal reflective screen is a molybdenum metal reflective screen, and the outer layer of the metal reflective screen is a stainless steel reflective screen. The furnace body is also provided with a high pressure cooling gas for connecting The furnace body is provided with a high-pressure air inlet and a high-pressure exhaust port for discharging high-pressure cooling gas; it also includes a vacuum system, which is connected to the furnace body; it also includes a water cooling system, which includes a heat exchanger, an air inlet duct and an air outlet duct; the air outlet duct is used as a return air duct; the water cooling system is arranged on the side of the furnace body, the air inlet duct has an interlayer, the interlayer is used as a water-cooled interlayer, and the two ends of the outer shell of the water-cooled interlayer are respectively provided with a water inlet and a water outlet; it also includes an exhaust fan; the upper end of the side wall of the furnace shell is connected to the heat exchanger through the air inlet duct, the heat exchanger is connected to the air inlet of the exhaust fan, and the air outlet of the exhaust fan is connected to the lower end of the side wall of the furnace shell through the return air duct.

[0008] The utility model adopts six steel columns to support the installation platform. The furnace body is arranged on the upper layer of the installation platform. The furnace shell and the furnace bottom are detachably connected. After disassembly, the furnace bottom and the workpiece are separated from the furnace body, which can facilitate the loading and unloading of the workpiece, save manpower and shorten the loading and unloading efficiency.

[0009] The shielding and insulation area in the brazing furnace uses a metal reflective screen. The inner layer is made of high-temperature resistant molybdenum metal material, and the outer layer is made of stainless steel material. It can effectively keep warm and reduce material costs while ensuring the cleanliness of the hot zone, meeting the aerospace industry's requirements for equipment cleanliness.

[0010] The brazing furnace is provided with a high-pressure gas inlet and a high-pressure gas exhaust port on the furnace side, which is convenient for accessing high-pressure cooling gas for gas quenching cooling. Its beneficial effects are, on the one hand, that gas quenching can meet the requirements of the aerospace industry for equipment cleanliness, and on the other hand, during high-pressure gas quenching, the high-pressure airflow can control the pressure and flow of the gas through a computer, change the cooling characteristics of the gas, and combine with the supercooled austenite transformation phase diagram of steel to achieve the most ideal quenching cooling and obtain the ideal metallographic structure, effective hardened layer depth and heat treatment distortion.

[0011] The brazing furnace is also integrated with a vacuum system, which can quickly provide a wide range of high vacuum for the brazing furnace to facilitate heat treatment work.

[0012] The water cooling system adopts a water-cooled sandwich structure on the air inlet duct, which solves the technical problem of overheating and deformation of the air inlet duct caused by high temperature. Therefore, external water cooling can be performed in the high-temperature section of the furnace, thereby improving the production efficiency of the brazing furnace.

[0013] The utility model eliminates the air-cooling motor on the furnace top cover and arranges an external water cooling system on the outside of the brazing furnace, which can reduce the total height of the equipment and facilitate the installation of the brazing furnace of the utility model in a factory building with insufficient floor height. At the same time, the water cooling system is arranged on the outside, which makes the cleaning and maintenance of the heat exchanger easier.

[0014] Furthermore, the electric heating system in the furnace body adopts metal electric heating elements, the hot zone is divided into six layers, each layer adopts a triangle connection method, and is evenly distributed along the circumference of the hot zone; the metal electric heating elements are connected to the external wiring through six water-cooled electrodes on the outer wall of the furnace shell.

[0015] The electric heating system of the utility model adopts metal electric heating elements, which can meet the requirements of the aerospace industry for equipment cleanliness. The entire hot zone is divided into six layers, each layer adopts a triangle, and there are 18 heating elements as a whole, which are evenly distributed along the circumference of the heating zone. Therefore, the heating power of the heating elements can be more effectively controlled by the temperature control system, so that the furnace temperature control is more uniform, more consistent with the set heating curve, and the product quality of the hot-processed workpiece is improved.

[0016] Furthermore, the vacuum system includes a vacuum on-off valve, a first-level vacuum pump group for achieving preliminary vacuum, and a second-level vacuum pump group for achieving deep vacuum; the first-level vacuum pump group includes a sliding valve pump as a front-stage pump, and two Roots vacuum pumps as secondary pumps, which are called the first Roots vacuum pump and the second Roots vacuum pump; the sliding valve pump is connected to the second Roots vacuum pump through a pipeline, the second Roots vacuum pump is connected to the first Roots vacuum pump, and the first Roots vacuum pump is connected to the pipeline connection port on the outside of the vacuum on-off valve through a pipeline, which are connected in sequence to form a preliminary vacuum gas path; the second-level vacuum pump group includes an oil diffusion pump and a bipolar rotary vane pump; the oil diffusion pump includes an air intake port and an exhaust port; the bipolar rotary vane pump includes an air intake port; the lower end of the vacuum on-off valve is connected to the air intake port of the oil diffusion pump, and the exhaust port of the oil diffusion pump is connected to the air intake port of the bipolar rotary vane pump, which are connected in sequence to form a wide-range deep vacuum gas path.

[0017] The utility model adopts two Roots vacuum pumps connected in series at the secondary stage to increase the exhaust capacity and exhaust speed, improve the vacuum degree, shorten the exhaust time, and improve the work efficiency; the sliding valve pump as the front pump and the two Roots pumps as the secondary pumps are connected in series as a pump group to quickly reach a certain vacuum degree, and the oil diffusion pump is adopted to enable the system to reach a higher vacuum degree, so as to achieve a wide-range and fast vacuum acquisition system.

[0018] Further optimization is carried out in which a cold trap is included between the vacuum on-off valve and the oil diffusion pump. The cold trap adopts a cylindrical cold trap mechanism with an external cold source. The lower end of the vacuum on-off valve is connected to the air inlet of the cold trap, and the air outlet of the cold trap is connected to the air intake of the oil diffusion pump. The cold trap includes a condensing plate for intercepting and cooling the oil vapor mixed in the air path of the vacuum on-off valve.

[0019] The cold trap is an existing technology. The cold trap includes a condensing plate. When the oil vapor mixed with the oil diffusion pump enters and exits the air path of the vacuum on-off valve, it will pass through the condensing plate on the cold trap. The low-temperature condensing plate can cool and condense the oil vapor, preventing the oil vapor from entering the interior of the equipment and contaminating parts. It can meet the aerospace industry's requirements for equipment cleanliness. The cold trap technology can also increase the vacuum degree by about 0.8 to 1 orders of magnitude.

[0020] Furthermore, the heat exchanger adopts a tube-row heat exchanger, including a tube shell, a heat source inlet and a heat source outlet are arranged at both ends of the tube shell, a cold source inlet and a cold source outlet are arranged at both ends of the outer wall of the tube shell, and a guide pipe is arranged axially inside the tube-row heat exchanger, and the cold source fluid enters the tube shell through the cold source inlet, flows through the guide pipe and then flows out from the cold source outlet; the furnace body is connected to the heat source inlet of the heat exchanger through an air inlet duct, the heat source outlet of the heat exchanger is connected to the air inlet of the exhaust fan, and the air outlet of the exhaust fan is connected to the furnace body through the return air duct, so as to form a gas passage for circulating and cooling the gas in the furnace in turn; the outer wall of the shell of the air inlet duct is provided with a heat sink, and a cooling fan is also provided, and the air outlet of the cooling fan faces the heat sink.

[0021] The utility model adopts a water-cooled interlayer for the air inlet duct and injects water for forced cooling, which solves the problem of overheating and deformation of the connecting pipe caused by high temperature. Furthermore, a heat sink is arranged on the outer wall of the shell of the air inlet duct, and a cooling fan is arranged to perform air cooling on the heat sink. The water-cooled and air-cooled mixed mode further reduces the problem of overheating and deformation. Therefore, an external water-cooled heat exchange system can be introduced for cooling when the furnace is still at a high temperature.

[0022] The high-temperature gas enters the heat exchanger through the air inlet duct, and the high-temperature gas is heat exchanged and cooled in the heat exchanger. The heat exchanger adopts a tube-column heat exchanger, which has the advantages of simple structure, small size, and easy and convenient cleaning and maintenance. In the tube-column heat exchanger, the high-temperature gas passes through multiple guide tubes, which are immersed in the cold source fluid. The high-temperature gas exchanges heat and cools down through the guide tubes and the cold source fluid. The cooled gas returns to the brazing furnace through the exhaust fan outlet and the return air duct, achieving an efficient cooling effect on the high-temperature gas in the brazing furnace and improving the working efficiency of the brazing furnace.

[0023] For further optimization, a bellows is provided in the air inlet duct for absorbing overheating and expansion of the air inlet duct.

[0024] The air inlet duct is used to guide high-temperature gas. During the diversion process, the duct is heated and its length will expand due to thermal expansion and contraction. Therefore, a bellows is connected in the middle to absorb the expansion deformation caused by thermal expansion and contraction through the elasticity of the bellows, thereby eliminating the damage caused by deformation when the air inlet duct is directly connected to the heat exchanger.

[0025] For further optimization, an asbestos filter for filtering gas is also provided between the air inlet duct and the heat source inlet of the heat exchanger.

[0026] The utility model utilizes the asbestos filter to filter tiny particles in high-temperature gas or harmful substances produced in brazing to purify the protective gas returned to the furnace and improve the cleanliness of the equipment.

[0027] Furthermore, a lifting mechanism is provided on the outer wall of the column; a lifting motor is provided on the mounting platform; the furnace bottom is provided on the lifting mechanism; a freight rail is provided on the ground below the furnace bottom; and the lifting motor is connected to the power input end of the lifting mechanism.

[0028] The utility model sets the furnace bottom on the lifting mechanism between the columns, and drives the lifting mechanism to drive the furnace bottom to separate from the furnace body through the lifting motor, and land on the freight rails on the ground. The furnace bottom and the workpiece can be moved out together with the freight rails with little effort, which is convenient for unloading or loading. After reloading, the furnace bottom and the workpiece are moved to the bottom of the brazing furnace through the freight rails, and then the furnace bottom is installed back on the furnace body by the lifting mechanism, which can save manpower and shorten the loading and unloading time, thereby improving work efficiency.

[0029] The beneficial effects of the utility model are:

[0030] 1. Multi-layer metal reflective screens are used in the hot zone of the brazing furnace, which can effectively keep the heat and reduce material costs while ensuring the cleanliness of the hot zone; the heating system uses multiple sets of temperature-controlled and adjustable metal heating elements, which is beneficial to maintaining cleanliness while ensuring the temperature uniformity in the furnace, meeting the requirements of the aerospace industry for equipment cleanliness;

[0031] 2. The use of a multi-stage vacuum pump group, especially two Roots vacuum pumps, increases the exhaust capacity and exhaust speed, shortens the exhaust time, and uses an oil diffusion pump to enable the system to reach a higher vacuum degree, thereby improving the working efficiency of the vacuum system and facilitating heat treatment work.

[0032] 3. The use of a water-cooled interlayer for the air inlet duct solves the technical problem that the air inlet duct is easily overheated and deformed, so that the external cooling can be performed after the heat treatment of the brazing furnace is completed, without having to wait until the temperature reaches a low temperature before external water cooling, thereby improving the working efficiency of the brazing furnace; in addition, since the external water cooling is placed on the side, the total height of the equipment is reduced, making it easier for more factories with insufficient floor height to install the brazing furnace of the present application, and also making the cleaning and maintenance of the heat exchanger easier.

[0033] 4. The furnace bottom is set on the lifting mechanism, which is convenient for disassembly and loading and unloading, saving manpower and shortening loading and unloading time, thus improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following briefly introduces the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0035] Figure 1 It is a schematic diagram of the utility model;

[0036] Figure 2 This is a cross-sectional view of the insulation layer in the furnace of the utility model;

[0037] Figure 3 It is a schematic diagram of the utility model from another angle.

[0038] Explanation of symbols:

[0039] 1. Furnace body; 2. Vacuum system; 3. Air inlet duct; 4. Heat exchanger; 5. Exhaust fan; 6. First-stage vacuum pump group; 7. Return air duct; 8. Water-cooled electrode; 9. Installation platform; 10. Metal reflective screen; 11. Electric heating element; 12. High-pressure air inlet; 13. Lifting motor; 14. Lifting mechanism; 15. High-pressure exhaust port; 16. Freight rail. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned purposes, features and advantages of the present invention more understandable, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0041] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0042] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general proportion, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0043] Secondly, the "one embodiment" or "embodiment" referred to herein refers to a specific feature, structure or characteristic that can be included in at least one implementation of the utility model. The "in one embodiment" that appears in different places in this specification does not refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0044] Reference Figure 1 , Figure 2 , Figure 3As shown, it includes an installation platform 9 and a furnace body 1, and an electric heating system and an insulation area are also arranged in the furnace body 1. The installation platform 9 is a double-layer platform supported by columns; the furnace body 1 includes a furnace shell, a head and a furnace bottom, the upper end of the furnace shell is fixedly connected to the head, and the lower end of the furnace shell is detachably connected to the furnace bottom; the furnace body 1 is arranged on the upper layer of the platform through a mounting frame on the outer wall of the furnace shell; at least two layers of metal reflective screens 10 are used in the insulation area of ​​the furnace body 1, the inner layer of the metal reflective screen 10 is a molybdenum metal reflective screen, and the outer layer of the metal reflective screen 10 is a stainless steel reflective screen; the furnace body 1 is also provided with a high-pressure air inlet 12 for connecting the high-pressure cooling gas and a high-pressure air inlet 12 for discharging the high-pressure cooling gas. A high-pressure exhaust port 15 for high-pressure cooling gas; a vacuum system 2 is also included, and the vacuum system 2 is connected to the furnace body 1; a water cooling system is also included, and the water cooling system includes a heat exchanger 4, an air inlet duct 3 and an air outlet duct; the air outlet duct is used as a return air duct 7; the water cooling system is arranged on the side of the furnace body 1, and the air inlet duct 3 has an interlayer, which serves as a water-cooled interlayer, and the two ends of the outer shell of the water-cooled interlayer are respectively provided with a water inlet and a water outlet; an exhaust fan 5 is also included; the upper end of the side wall of the furnace shell is connected to the heat exchanger 4 through the air inlet duct 3, the heat exchanger 4 is connected to the air inlet of the exhaust fan 5, and the air outlet of the exhaust fan 5 is connected to the lower end of the side wall of the furnace shell through the return air duct 7.

[0045] In this embodiment, the installation platform 9 is a two-layer platform formed by using multiple steel sections as columns to support multiple steel beams. Steel plates are laid around the steel beams to install auxiliary facilities around the furnace body 1. No steel plates are laid in the middle where the furnace body 1 is set. The upper and lower layers are connected, and the furnace body 1 is set on the upper layer of the installation platform 9 through four installation brackets on the outside of the furnace shell.

[0046] In this embodiment, the furnace shell, furnace door, head and furnace bottom are all double-layer shells with cooling water flowing inside. The furnace shell is cylindrical, and the furnace shell and the head are welded with airtight welds. The furnace shell and the furnace bottom are detachably connected. After disassembly, the furnace bottom together with the workpiece can be separated from the furnace body 1, which is convenient for loading and unloading of workpieces, saving manpower and shortening loading and unloading efficiency.

[0047] In this embodiment, the brazing furnace is also integrated with a vacuum system 2, and the first-level vacuum pump group 6 is used for preliminary vacuuming. When the vacuum reaches a certain value, the second-level vacuum pump group is started. The second-level vacuum pump group quickly provides a wide range of high vacuum for the brazing furnace to facilitate heat treatment.

[0048] In this embodiment, the fan motor on the furnace top cover is removed, and the external water cooling system is arranged on the furnace side, which can reduce the total height of the brazing furnace equipment, so that the brazing furnace of this embodiment can be installed in the workshop with insufficient floor height. At the same time, the water cooling system installed on the outside also makes the cleaning and maintenance of the heat exchanger 4 easier;

[0049] In this embodiment, the shielding and heat-insulating layer in the brazing furnace adopts a metal reflective screen 10, the inner layer of which is made of high-temperature resistant molybdenum metal material, and the outer layer is made of stainless steel material. It can effectively keep warm and reduce material costs while ensuring the cleanliness of the hot zone, meeting the aerospace industry's requirements for equipment cleanliness.

[0050] The purpose of quenching is to transform the supercooled austenite into martensite or bainite to obtain martensite or bainite structure, and then combine it with tempering at different temperatures to greatly improve the rigidity, hardness, wear resistance, fatigue strength and toughness of the steel, so as to meet the different use requirements of various mechanical parts and tools.

[0051] In this embodiment, a high-pressure air inlet 12 is provided on the side of the furnace shell of the furnace body 1 to allow high-pressure cooling gas to be introduced for gas quenching. Experimental data show that the cooling speed of high-pressure gas quenching in a vacuum environment is better than that of salt bath quenching.

[0052] The test material is 100kg high speed steel When the end mill is quenched and cooled from 1190℃ to 650℃, the cooling rate data of salt bath quenching and vacuum high pressure (5MPa) gas quenching are shown in the following table:

[0053]

[0054] The data in the table show that the larger the workpiece size, the greater the cooling speed advantage of vacuum high-pressure gas quenching.

[0055] During high-pressure gas quenching, the high-pressure airflow can control the pressure and flow of the gas through a computer, change the cooling characteristics of the gas, and combine with the supercooled austenite transformation phase diagram of steel to achieve the most ideal quenching cooling and obtain the ideal metallographic structure, effective hardened layer depth and heat treatment distortion.

[0056] The electric heating system in the furnace body 1 adopts metal electric heating elements 11, and the hot zone is divided into six layers. Each layer adopts a triangle connection method and is evenly distributed along the circumference of the hot zone; the metal electric heating elements 11 are connected to the external wiring through six water-cooled electrodes 8 on the outer wall of the furnace shell.

[0057] In this embodiment, the electric heating system adopts a metal electric heating element 11, which can meet the requirements of the aerospace industry for equipment cleanliness. The entire hot zone is divided into six layers, each layer adopts a triangle, and there are 18 heating elements in total, which are evenly distributed along the circumference of the hot zone. Therefore, the heating power of the heating element can be more effectively controlled by the temperature control system, so that the furnace temperature control is more uniform, more consistent with the set heating curve, and the product quality of the hot-processed workpiece is improved.

[0058] The electric heating element 11 is generally a metal molybdenum strip or molybdenum wire, tungsten, tantalum, nickel-chromium, iron-chromium-aluminum or other metal electric heating element, and all of the above electric heating elements 11 can be used in this embodiment.

[0059] The vacuum system 2 includes a vacuum on-off valve, a primary vacuum pump group 6 for achieving a preliminary vacuum, and a secondary vacuum pump group for achieving a deep vacuum; the primary vacuum pump group 6 includes a slide valve pump as a front pump, and two Roots vacuum pumps as secondary pumps, which are called a first Roots vacuum pump and a second Roots vacuum pump; the slide valve pump is connected to the second Roots vacuum pump through a pipeline, the second Roots vacuum pump is connected to the first Roots vacuum pump, the first Roots vacuum pump is connected to the pipeline connection port on the outer side of the vacuum on-off valve through a pipeline, and they are connected in sequence to form a preliminary vacuum gas path; the secondary vacuum pump group includes an oil diffusion pump and a bipolar rotary vane pump; the oil diffusion pump includes an air intake port and an exhaust port; the bipolar rotary vane pump includes an air intake port; the lower end of the vacuum on-off valve is connected to the air intake port of the oil diffusion pump, and the exhaust port of the oil diffusion pump is connected to the air intake port of the bipolar rotary vane pump, and they are connected in sequence to form a wide-range deep vacuum gas path.

[0060] In this embodiment, two Roots vacuum pumps connected in series are used at the secondary stage to increase the exhaust capacity and exhaust speed, improve the vacuum degree, shorten the exhaust time, and thus improve work efficiency; a sliding valve pump as a front pump and two Roots pumps connected in series as secondary pumps as a pump group can quickly reach a certain vacuum degree, and an oil diffusion pump is used to enable the system to reach a higher vacuum degree, so as to achieve a wide-range and fast vacuum acquisition system.

[0061] When the vacuum system 2 is working, first start the slide valve pump and the bipolar rotary vane pump, heat the oil diffusion pump, then open the front valve behind the slide valve pump and the maintenance valve behind the bipolar rotary vane pump to evacuate the oil diffusion pump. When the vacuum degree reaches a certain set value of the system, the first and second Roots vacuum pumps are started, then the bypass valve is opened, and the front valve is closed. At this time, the vacuum chamber is evacuated to a low vacuum. When the oil diffusion pump is heated to the specified temperature and the vacuum degree is higher than the specified value, the vacuum on-off valve is opened, the bypass valve is closed, and the front valve is opened again. At this time, the oil diffusion pump is turned on to evacuate the vacuum chamber to a high vacuum. After the vacuum degree required by the process is reached, heat treatment can be carried out. After the heat treatment process is completed, the vacuum chamber is filled with high-purity nitrogen for forced cooling to complete the entire process.

[0062] A cold trap is also provided between the vacuum on-off valve and the oil diffusion pump. The cold trap is a cylindrical cold trap mechanism with an external cold source. The lower end of the vacuum on-off valve is connected to the air inlet of the cold trap, and the air outlet of the cold trap is connected to the air intake of the oil diffusion pump. The cold trap includes a condensing sheet for intercepting and cooling the oil vapor mixed in the air path of the vacuum on-off valve to condense.

[0063] In this embodiment, the cold trap is a prior art, which includes a condensing plate. When the oil vapor mixed with the oil diffusion pump enters and exits the air path of the vacuum on-off valve, it will pass through the condensing plate on the cold trap. In this way, the low-temperature condensing plate can cool and condense the oil vapor, preventing the oil vapor from entering the interior of the equipment and contaminating parts. The requirements of the aerospace industry for equipment cleanliness can be met. The cold trap technology can also increase the vacuum degree by about 0.8 to 1 orders of magnitude.

[0064] The heat exchanger 4 adopts a tube-row heat exchanger, including a tube shell, with a heat source inlet and a heat source outlet at both ends of the tube shell, and a cold source inlet and a cold source outlet at both ends of the outer wall of the tube shell. A guide pipe is arranged axially inside the tube-row heat exchanger, and the cold source fluid enters the tube shell through the cold source inlet, flows through the guide pipe and then flows out from the cold source outlet; the furnace body 1 is connected to the heat source inlet of the heat exchanger 4 through the air inlet duct 3, and the heat source outlet of the heat exchanger 4 is connected to the air inlet of the exhaust fan 5, and the air outlet of the exhaust fan 5 is connected to the furnace body 1 through the return air duct 7, so as to form a gas passage for circulating and cooling the gas in the furnace in turn; the outer wall of the shell of the air inlet duct 3 is provided with a heat sink, and a cooling fan is also provided, and the air outlet of the cooling fan faces the heat sink.

[0065] In this embodiment, the air inlet duct 3 adopts a double-layer structure, and water is injected into the interlayer for forced cooling. The technical means of the water-cooled interlayer can solve the problem of overheating and deformation of the connecting pipes caused by high temperature. Furthermore, a heat sink is also provided on the outer wall of the shell of the air inlet duct 3, and a cooling fan is provided to cool the heat sink by air. The water-cooling and air-cooling mixed mode can further reduce the problem of overheating and deformation. Therefore, after solving the problem of overheating and deformation of the air inlet duct 3, an external water-cooling heat exchange system can be introduced for cooling when the furnace is still at a high temperature, thereby improving the cooling efficiency.

[0066] In this embodiment, the high-temperature gas enters the heat exchanger 4 through the air inlet duct 3, and the high-temperature gas is heat exchanged and cooled in the heat exchanger 4. The heat exchanger 4 adopts a tube-column heat exchanger, which has the advantages of simple structure, small size, and simple and convenient cleaning and maintenance. Inside the tube-column heat exchanger, multiple guide pipes are arranged along the axial direction. After the high-temperature gas enters from the heat source of the heat exchanger 4, it is diverted and passed through multiple guide pipes. The guide pipes are immersed in the cold source fluid. The high-temperature gas exchanges heat and cools down through the guide pipes and the cold source fluid. The cooled gas is connected to the air intake port of the exhaust fan 5 from the heat source outlet of the heat exchanger 4, and the gas is sent out of the air outlet through the turbofan of the exhaust fan 5, and returned to the brazing furnace through the return air duct 7, so as to achieve an efficient cooling effect on the high-temperature gas in the brazing furnace and improve the working efficiency of the brazing furnace.

[0067] A bellows is also provided in the air inlet duct 3 for absorbing overheating and expansion of the air inlet duct 3 .

[0068] In this embodiment, the air inlet duct 3 is used to guide high-temperature gas. During the guiding process, the duct is heated and its length is deformed due to thermal expansion and contraction. Therefore, a bellows is arranged in the middle of the air inlet duct 3 to eliminate the deformation of the air inlet duct 3 through the elasticity of the bellows.

[0069] An asbestos filter for filtering gas is also provided between the air inlet duct 3 and the heat source inlet of the heat exchanger 4 .

[0070] In this embodiment, an asbestos filter is used to filter tiny particles in high-temperature gas or harmful substances produced during brazing to purify the protective gas returned to the furnace and improve the cleanliness of the equipment.

[0071] The outer wall of the column is provided with a lifting mechanism 14; the installation platform 9 is provided with a lifting motor 13; the furnace bottom is arranged on the lifting mechanism 14; a freight guide rail 16 is arranged on the ground below the furnace bottom; and the lifting motor 13 is connected to the power input end of the lifting mechanism 14.

[0072] In this embodiment, a screw slider lifting mechanism 14 is provided on the outer wall of the steel column, and the furnace bottom is provided on the lifting mechanism 14. The lifting motor 13 drives the screw to drive the lifting mechanism 14 to move up and down. When unloading, the lifting mechanism 14 drives the furnace bottom to separate from the furnace body 1, and the rollers provided on the furnace bottom fall onto the freight rails 16 on the ground. The freight rails 16 can be used to move the furnace bottom together with the workpiece out of the installation platform 9 with little effort, which is convenient for unloading or loading. After reloading, the furnace bottom and the workpiece are moved to the bottom of the brazing furnace through the freight rails 16, and then the furnace bottom is lifted and installed back on the furnace body 1 by the lifting mechanism 14, which can save manpower, shorten the loading and unloading time, and improve work efficiency.

[0073] Furthermore, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment may not be described, i.e., those features that are not relevant to the best mode presently contemplated for carrying out the invention or those features that are not relevant to implementing the invention.

[0074] It should be understood that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but for those of ordinary skill having the benefit of this disclosure, the development effort will be a routine task of design, fabrication, and production without undue experimentation.

[0075] It should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. External circulation cooling metal screen high vacuum high pressure vertical brazing furnace, including a mounting platform and a furnace body, the furnace body is also provided with an electric heating system and a heat insulation area, the characteristics are: The installation platform is a double-layer platform supported by columns; The furnace body includes a furnace shell, a head and a furnace bottom. The upper end of the furnace shell is fixedly connected to the head, and the lower end of the furnace shell is detachably connected to the furnace bottom. The furnace body is arranged on the upper layer of the platform through a mounting frame on the outer wall of the furnace shell; The heat insulation area in the furnace body adopts at least two layers of metal reflective screens, the inner layer of the metal reflective screen is a molybdenum metal reflective screen, and the outer layer of the metal reflective screen is a stainless steel reflective screen; The furnace body is also provided with a high-pressure air inlet for receiving high-pressure cooling gas and a high-pressure exhaust port for exhausting high-pressure cooling gas; It also includes a vacuum system, which is connected to the furnace body; It also includes a water cooling system, which includes a heat exchanger, an air inlet duct and an air outlet duct; Use the air outlet duct as the return air duct; The water cooling system is arranged on the side of the furnace body, the air inlet duct has a sandwich layer, the sandwich layer serves as a water cooling sandwich layer, and the two ends of the outer shell of the water cooling sandwich layer are respectively provided with a water inlet and a water outlet; Also includes an exhaust fan; The upper end of the furnace shell side wall is connected to the heat exchanger through an air inlet duct, the heat exchanger is connected to the air inlet of the exhaust fan, and the air outlet of the exhaust fan is connected to the lower end of the furnace shell side wall through a return air duct.

2. The external circulation cooling metal screen high vacuum high pressure vertical brazing furnace according to claim 1 is characterized in that: The electric heating system in the furnace body adopts metal electric heating elements. The hot zone is divided into six layers, each layer adopts triangle connection method and is evenly distributed along the circumference of the hot zone; The metal electric heating element is connected to the external wiring through six water-cooled electrodes on the outer wall of the furnace shell.

3. The external circulation cooling metal screen high vacuum high pressure vertical brazing furnace according to claim 1 is characterized in that: The vacuum system includes a vacuum on-off valve, a primary vacuum pump group for achieving a preliminary vacuum, and a secondary vacuum pump group for achieving a deep vacuum; The first-stage vacuum pump group includes a slide valve pump as a front-stage pump and two Roots vacuum pumps as secondary pumps, which are called the first Roots vacuum pump and the second Roots vacuum pump; The slide valve pump is connected to the second Roots vacuum pump through a pipeline, the second Roots vacuum pump is connected to the first Roots vacuum pump, and the first Roots vacuum pump is connected to the pipeline connection port outside the vacuum on-off valve through a pipeline, and the pipelines are connected in sequence to form a preliminary vacuum gas path; The two-stage vacuum pump group includes an oil diffusion pump and a bipolar rotary vane pump; The oil diffusion pump includes an air intake port and an air exhaust port; The two-stage rotary vane pump includes a suction port; The lower end of the vacuum on-off valve is connected to the air intake of the oil diffusion pump, and the exhaust port of the oil diffusion pump is connected to the air intake of the bipolar rotary vane pump, which are connected in sequence to form a wide-range deep vacuum gas path.

4. The external circulation cooling metal screen high vacuum high pressure vertical brazing furnace according to claim 3 is characterized in that: A cold trap is also provided between the vacuum on-off valve and the oil diffusion pump. The cold trap is a cylindrical cold trap mechanism with an external cold source. The lower end of the vacuum on-off valve is connected to the air inlet of the cold trap, and the air outlet of the cold trap is connected to the air intake of the oil diffusion pump. The cold trap includes a condensing sheet for intercepting, cooling and condensing the oil vapor mixed in the gas path of the vacuum on-off valve.

5. The external circulation cooling metal screen high vacuum high pressure vertical brazing furnace according to claim 1 is characterized in that: The heat exchanger adopts a tube-column heat exchanger, including a tube shell, a heat source inlet and a heat source outlet are arranged at both ends of the tube shell, a cold source inlet and a cold source outlet are arranged at both ends of the outer wall of the tube shell, and a guide pipe is arranged inside the tube-column heat exchanger along the axial direction. The cold source fluid enters the tube shell through the cold source inlet, flows through the guide pipe and flows out from the cold source outlet; The furnace body is connected to the heat source inlet of the heat exchanger through the air inlet duct, the heat source outlet of the heat exchanger is connected to the air inlet of the exhaust fan, and the air outlet of the exhaust fan is connected to the furnace body through the return air duct, thereby forming a gas passage for gas circulation cooling in the furnace; The outer wall of the shell of the air inlet duct is provided with a heat sink, and a cooling fan is also provided, and the air outlet of the cooling fan faces the heat sink.

6. The external circulation cooling metal screen high vacuum high pressure vertical brazing furnace according to claim 5 is characterized in that: A bellows is also provided in the air inlet duct for absorbing overheating and expansion of the air inlet duct.

7. The external circulation cooling metal screen high vacuum high pressure vertical brazing furnace according to claim 5 is characterized in that: An asbestos filter for filtering gas is also provided between the air inlet duct and the heat source inlet of the heat exchanger.

8. The external circulation cooling metal screen high vacuum high pressure vertical brazing furnace according to claim 1 is characterized in that: The outer wall of the column is provided with a lifting mechanism; the mounting platform is provided with a lifting motor; The furnace bottom is arranged on a lifting mechanism; Freight rails are provided on the ground below the furnace bottom; The lifting motor is connected to the power input end of the lifting mechanism.

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