Efficient energy-saving well type carburizing furnace

Abstract

This invention provides a high-efficiency and energy-saving pit-type carburizing furnace, relating to the technical field of pit-type carburizing furnaces. It includes: a main carburizing furnace body, an upper sealed furnace cover, a carburizing agent pipe, and an internal circulation fan. The top of the main carburizing furnace body is sealed with the upper sealed furnace cover. A carburizing agent pipe is fixedly installed on the upper part of the upper sealed furnace cover, and an internal circulation fan is installed below the upper sealed furnace cover. An inner heat-insulating furnace lining is fixedly installed inside the main carburizing furnace body. An inner spiral air guide groove is provided on the inner side of the inner heat-insulating furnace lining, and an inner carburizing boss is convexly provided on the bottom of the inner heat-insulating furnace lining. The airflow is guided downward by the inner spiral air guide groove, carrying the carburizing agent flowing out of the lower extension pipe downward, promoting the uniform distribution of the carburizing agent inside the inner heat-insulating furnace lining, shortening the time required for uniform carbon potential atmosphere, and solving the problem that downward airflow easily cancels out upward hot air, making it difficult for the airflow to reach the bottom of the pit-type carburizing furnace, and requiring a longer time for carburizing agent uniformity.

Description

Technical Field

[0001] This invention relates to the field of pit-type carburizing furnace technology, and in particular to a high-efficiency and energy-saving pit-type carburizing furnace. Background Technology

[0002] Pit-type carburizing furnaces are used for surface carburizing treatment of cast iron and cast steel parts. Through carbonization in a high-temperature environment, carbon atoms are diffused into the metal surface, increasing the metal's hardness and wear resistance. They feature a bottom-opening design, utilizing natural convection and diffusion to achieve the carburizing process. Pit-type carburizing furnaces are widely used in industries such as automotive and machinery manufacturing to improve product quality and performance.

[0003] The top opening of the pit-type carburizing furnace is sealed with a furnace cover. The furnace cover is lifted away from the pit-type carburizing furnace by a lifting device. A fan is installed on the top of the furnace cover to circulate the airflow inside the pit-type carburizing furnace. The airflow driven by the fan moves downward. The airflow lacks path planning, and the downward airflow is easily canceled out by the upward hot air, making it difficult for the airflow to reach the bottom of the pit-type carburizing furnace. It takes a longer time for the carburizing agent to be evenly distributed. The longer the pit-type carburizing furnace runs, the higher its power consumption. Summary of the Invention

[0004] This disclosure relates to a high-efficiency and energy-saving well-type carburizing furnace. The airflow in the outlet pipe is guided downward by the inner spiral air guide groove. As the airflow moves downward, it carries the carburizing agent flowing out of the lower extension pipe downward. The downward flow distance of the airflow is longer, which promotes the uniform distribution of the carburizing agent inside the inner heat insulation furnace lining, shortens the time for the internal carbon potential atmosphere to become uniform, and shortens the processing time of the carburizing furnace, thereby achieving the purpose of energy saving and emission reduction. The inner spiral air guide groove guides the external airflow to move downward, and the air inlet of the lower air inlet of the internal circulation fan guides the airflow in the middle to move upward, forming an airflow trend of downward movement outside and upward movement in the middle. External heat quickly gathers towards the location of the components in the middle, accelerating the heating rate of the components in the middle. At the same time, the carburizing agent carried by the airflow comes into contact with the components in the middle, further accelerating the carburizing speed of the components and shortening the processing time of the carburizing furnace.

[0005] In a first aspect, this disclosure provides a high-efficiency and energy-saving pit-type carburizing furnace, specifically comprising: a main carburizing furnace body, an upper sealed furnace cover, a carburizing agent pipe, and an internal circulation fan. The top of the main carburizing furnace body is fitted and sealed with the upper sealed furnace cover. A carburizing agent pipe is fixedly installed on the upper part of the upper sealed furnace cover, and an internal circulation fan is installed below the upper sealed furnace cover. An inner heat-insulating furnace lining is fixedly installed inside the main carburizing furnace body. The inner heat-insulating furnace lining is made of fireproof and heat-insulating material and forms a cylindrical structure inside the main carburizing furnace body. An inner spiral air guide groove is provided on the inner side of the inner heat-insulating furnace lining, and an inner spiral heating element is fixed on the inner side of the inner heat-insulating furnace lining. A lower sealing ring is fixed on the outer side of the top of the main carburizing furnace body, and an inner carburizing boss is convexly provided on the bottom of the inner heat-insulating furnace lining.

[0006] In at least some embodiments, the inner spiral air guide groove of the inner heat insulation furnace lining is recessed, and the inner spiral air guide groove and the inner spiral heating element are staggered. The inner spiral air guide groove and the inner spiral heating element are both surrounding the outer side of the inner carburized boss. The airflow of the exhaust pipe is guided downward by the inner spiral air guide groove. The airflow flows downward in a spiral shape along the inner spiral air guide groove. The guidance of the inner spiral air guide groove makes the downward flow distance of the airflow longer.

[0007] In at least some embodiments, the bottom of the upper closed furnace cover is provided with a lower boss bracket, the bottom of the upper closed furnace cover is fixedly provided with an upper sealing ring, the outer side of the bottom of the upper closed furnace cover is fixedly provided with an outer telescopic heat insulation ring, and the upper closed furnace cover is fixedly provided with a waste gas pipe.

[0008] In at least some embodiments, the upper sealing ring surrounds the outside of the lower boss frame, and the upper sealing ring and the lower sealing ring slide and fit together vertically for sealing. The outer telescopic heat insulation ring surrounds the outside of the upper sealing ring, and the lower end of the exhaust pipe extends to the outside of the bottom of the lower boss frame. After the outer telescopic heat insulation ring is extended, its lower end fits with the top of the main carburizing furnace body.

[0009] In at least some embodiments, the lower end of the exudate tube is slidably connected to a lower extension tube, a bracket fixed to the outside of the lower extension tube and a threaded lifting rod are screwed together, and the top end of the exudate tube is connected to an upper connecting tube.

[0010] In at least some embodiments, the three carburizing pipes connected by the upper connecting pipe are arranged in a spaced array. The three carburizing pipes arranged in a horizontal ring and the lower extension pipe expand the carburizing agent discharge range in the horizontal position. The number of carburizing pipes can be adjusted as needed. The lower extension pipe and the lower boss are axially slidably connected. The threaded lifting rod and the upper closed furnace cover are rotatably connected. The lower end of the lower extension pipe extends to the outer side of the bottom of the lower boss.

[0011] In at least some embodiments, the outer side of the internal circulation fan is connected to an air outlet pipe, the bottom of the internal circulation fan is fixed with a lower air inlet external isolation pipe, the central fan blade of the internal circulation fan and the main shaft of the upper drive motor are fixed, and the upper drive motor is fixed to the top of the upper closed furnace cover.

[0012] In at least some embodiments, the exhaust pipe is a ring-shaped curved pipe structure with the tail end of the exhaust pipe facing the inner spiral air guide groove. The lower air inlet outer isolation pipe is wrapped around the outside of the bottom inlet of the inner circulation fan. The lower air inlet outer isolation pipe isolates the bottom inlet of the inner circulation fan to prevent the exhaust pipe from being directly introduced into the bottom inlet of the inner circulation fan. The lower air inlet outer isolation pipe is located vertically above the inner carburized boss. The air inlet inside the lower air inlet outer isolation pipe of the inner circulation fan guides the airflow in the middle to move upward.

[0013] This invention provides a high-efficiency and energy-saving pit-type carburizing furnace, which has the following beneficial effects:

[0014] The airflow in the outlet pipe is guided downward by the inner spiral air guide groove. As the airflow moves downward, it carries the carburizing agent flowing out of the lower extension pipe downward. The downward flow distance of the airflow is longer, which promotes the uniform distribution of the carburizing agent inside the inner heat insulation furnace lining, shortens the time for the internal carbon potential atmosphere to become uniform, shortens the processing time of the carburizing furnace, and achieves the purpose of energy saving and emission reduction.

[0015] The inner spiral air guide groove guides the external airflow downwards, while the inner air inlet of the lower air inlet of the internal circulation fan guides the airflow in the middle upwards, forming an airflow trend of downward movement in the outside and upward movement in the middle. External heat quickly gathers towards the location of the middle components, accelerating the heating rate of the middle components. At the same time, the carburizing agent carried by the airflow comes into contact with the middle components, further accelerating the carburizing speed of the components and shortening the processing time of the carburizing furnace.

[0016] Three lower extension tubes expand the horizontal range of carbonizing agent discharge. The threaded lifting rod guides the lower extension tubes to move axially, allowing them to penetrate deeper into the inner insulation lining and expand the range of carbonizing agent at different vertical depths, thus accelerating the diffusion efficiency of the carbonizing agent.

[0017] During the upward movement of the upper closed furnace cover, the outer telescopic heat insulation ring moves upward and fits against the top of the main carburizing furnace body. The outer telescopic heat insulation ring isolates the flame between the upper closed furnace cover and the main carburizing furnace body, preventing the flame from escaping outward along the gap between the upper closed furnace cover and the main carburizing furnace body and endangering the surrounding personnel. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0019] The accompanying drawings described below are only related to some embodiments of the invention and are not intended to limit the invention.

[0020] In the attached diagram:

[0021] Figure 1 A schematic diagram of the overall structure of this application is shown;

[0022] Figure 2 This paper shows a schematic diagram of the longitudinal half-section structure of the main carburizing furnace body and the inner heat insulation lining of this application;

[0023] Figure 3 A schematic diagram of the internal spiral heating element structure of this application is shown;

[0024] Figure 4 A schematic diagram of the internal circulation fan structure of this application is shown;

[0025] Figure 5 A schematic diagram of the exudate tube of this application is shown;

[0026] Figure 6 A schematic diagram of the structure of the external telescopic heat insulation ring of this application is shown;

[0027] Figure 7 A schematic diagram of the internal spiral air guide groove of this application is shown;

[0028] Figure 8 A schematic diagram of the structure of the main carburizing furnace body and the upper closed furnace cover in the separated state of this application is shown.

[0029] List of reference numerals

[0030] 1. Main carburizing furnace body; 101. Inner heat insulation furnace lining; 102. Inner spiral air guide groove; 103. Inner spiral heating element; 104. Lower sealing ring; 105. Inner carburizing boss;

[0031] 2. Upper closed furnace cover; 201. Lower boss frame; 202. Upper sealing ring; 203. Outer telescopic heat insulation ring; 204. Exhaust gas pipe;

[0032] 3. Permeate pipe; 301. Lower extension pipe; 302. Threaded lifting rod; 303. Upper connecting pipe;

[0033] 4. Internal circulation fan; 401. Air outlet pipe; 402. Lower air inlet external isolation pipe; 403. Upper drive motor. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] Example 1: Please refer to Figures 1 to 8 :

[0036] This invention proposes a high-efficiency and energy-saving pit-type carburizing furnace, comprising: a main carburizing furnace body 1, an upper closed furnace cover 2, a carburizing agent pipe 3, and an internal circulation fan 4. An inner heat-insulating furnace lining 101 is fixedly installed inside the main carburizing furnace body 1. The inner heat-insulating furnace lining 101 is made of fireproof and heat-insulating material and forms a cylindrical structure inside the main carburizing furnace body 1. An inner spiral air guide groove 102 is provided on the inner side of the inner heat-insulating furnace lining 101, and an inner spiral heating element 103 is fixed on the inner side of the inner heat-insulating furnace lining 101. A lower sealing ring 104 is fixed on the outer side of the top of the main carburizing furnace body 1. An inner carburizing boss 105 is protruding from the bottom of the inner heat-insulating furnace lining 101. An upper closed furnace cover 2 is fitted and sealed to the top of the main carburizing furnace body 1, and a lower boss bracket 20 is protruding from the bottom of the upper closed furnace cover 2. 1. An upper sealing ring 202 is fixedly installed at the bottom of the upper closed furnace cover 2. An outer telescopic heat insulation ring 203 is fixedly installed on the outer side of the bottom of the upper closed furnace cover 2. An exhaust pipe 204 is fixedly installed through the upper closed furnace cover 2. An infiltrator pipe 3 is fixedly installed at the upper part of the upper closed furnace cover 2. The lower end of the infiltrator pipe 3 is slidably connected to a lower extension pipe 301. A bracket fixed on the outer side of the lower extension pipe 301 is screwed to a threaded lifting rod 302. The top end of the infiltrator pipe 3 is connected to an upper connecting pipe 303. An internal circulation fan 4 is installed below the upper closed furnace cover 2. An exhaust pipe 401 is connected to the outer side of the internal circulation fan 4. An outer isolation pipe 402 for the lower air inlet is fixed at the bottom of the internal circulation fan 4. The central fan blade of the internal circulation fan 4 is fixed to the main shaft of the upper drive motor 403. The upper drive motor 403 is fixed to the top of the upper closed furnace cover 2.

[0037] In this embodiment, the inner spiral air guide groove 102 of the inner heat insulation furnace lining 101 is recessed, and the inner spiral air guide groove 102 and the inner spiral heating element 103 are staggered. The inner spiral air guide groove 102 and the inner spiral heating element 103 are both surrounding the outer side of the inner carburized boss 105. The airflow of the exhaust pipe 401 is guided downward by the inner spiral air guide groove 102. The airflow flows downward in a spiral shape along the inner spiral air guide groove 102. The guidance of the inner spiral air guide groove 102 makes the downward flow distance of the airflow... The upper connecting pipe 303 is connected to the supply pipeline of the carburizing agent. The carburizing agent is connected to the carburizing agent pipe 3 and the lower extension pipe 301 through the upper connecting pipe 303. The carburizing agent flows out of the lower extension pipe 301. The airflow of the outlet pipe 401 flows downward while carrying the carburizing agent flowing out of the lower extension pipe 301 downward. This promotes the uniform distribution of the carburizing agent in the vertical direction inside the inner heat insulation furnace lining 101, shortens the time for the internal carbon potential atmosphere to become uniform, shortens the processing time and processing energy consumption of the carburizing furnace, and saves energy and reduces emissions.

[0038] In this embodiment, the upper sealing ring 202 surrounds the outside of the lower boss frame 201, and the upper sealing ring 202 and the lower sealing ring 104 slide vertically and fit together for sealing. The outer telescopic heat insulation ring 203 surrounds the outside of the upper sealing ring 202. The lower end of the exhaust pipe 204 extends to the outside of the bottom of the lower boss frame 201. After the outer telescopic heat insulation ring 203 is extended, its lower end fits against the top of the main carburizing furnace body 1. The outer telescopic heat insulation ring 203 isolates the flames that emerge outward between the upper closed furnace cover 2 and the main carburizing furnace body 1, preventing the flames from escaping outward along the gap between the upper closed furnace cover 2 and the main carburizing furnace body 1 and endangering the surrounding personnel.

[0039] In this embodiment, the three carburizing pipes 3 connected by the upper connecting pipe 303 are arranged in a spaced array. The three carburizing pipes 3 arranged in a horizontal ring and the lower extension pipe 301 expand the horizontal carburizing agent discharge range. The number of carburizing pipes 3 can be adjusted as needed. The lower extension pipe 301 and the lower boss frame 201 are axially slidably connected. The threaded lifting rod 302 and the upper closed furnace cover 2 are rotatably connected. The lower end of the lower extension pipe 301 extends to the outer side of the bottom of the lower boss frame 201. The lower extension pipe 301 moves deeper into the inner heat insulation furnace lining 101. The lower extension pipe 301 is set at different heights to expand the carburizing agent range at different vertical depths, thereby accelerating the carburizing agent diffusion efficiency.

[0040] In this embodiment, the exhaust pipe 401 is an annular curved pipe structure, with its tail end facing the inner spiral air guide groove 102. The lower air inlet outer isolation pipe 402 surrounds the outside of the bottom inlet of the internal circulation fan 4, isolating the bottom inlet of the internal circulation fan 4 and preventing the exhaust from the exhaust pipe 401 from being directly introduced into the bottom inlet of the internal circulation fan 4. The lower air inlet outer isolation pipe 402 is located vertically above the inner carburized boss 105, and the air inlet inside the lower air inlet outer isolation pipe 402 of the internal circulation fan 4 guides the airflow in the middle to move upward. The internal heat insulation furnace lining 101 moves in conjunction with the external downward movement of the internal spiral air guide channel 102 and the upward movement of the airflow in the middle of one side of the internal carburizing boss 105. The airflow is split and circulated vertically. The external heat of the internal spiral air guide channel 102 quickly gathers and flows upward towards the parts located on the upper part of the internal carburizing boss 105, accelerating the heating speed of the middle parts. At the same time, during the process of the airflow gathering and flowing upward, the carburizing agent carried in the airflow comes into contact with the middle parts, further accelerating the carburizing speed of the parts. The pit-type carburizing furnace has a shorter operating time and lower power consumption.

[0041] In Example 2, based on Example 1, air guide walls are provided on the upper and lower edges of the inner spiral air guide groove 102. The air guide walls increase the air guiding capacity of the inner spiral air guide groove 102, enhance the downward flow of air, and promote the uniform speed of the internal carbon potential atmosphere. The inner spiral heating element 103 can be further integrated into the inner spiral air guide groove 102, and the width of the inner spiral air guide groove 102 is further expanded, further promoting the air guiding capacity, and also promoting uniform heating and temperature rise inside.

[0042] The working principle of this embodiment is as follows: The main carburizing furnace body 1 is equipped with an inner heat-insulating lining 101 for heat preservation. An inner spiral heating element 103 heats the interior of the inner heat-insulating lining 101. The main carburizing furnace body 1 and the inner heat-insulating lining 101 form the inlet. An upper closed furnace cover 2 is connected to a lifting device. The upper closed furnace cover 2 is automatically raised by the lifting device, separating from the main carburizing furnace body 1 and rotating to one side. The parts to be carburized are placed in a basket, which is positioned above the inner carburizing boss 105. The upper closed furnace cover 2 descends, and the upper sealing ring 202 and lower sealing ring 104 seal the furnace. The upper drive motor 403 starts, driving the blades of the internal circulation fan 4 to rotate. The air outlet pipe 401 of the internal circulation fan 4 blows air outwards. The air outlet pipe 401 is directed towards the inner spiral air guide groove 102. The airflow in the air outlet pipe 401 is guided downwards by the inner spiral air guide groove 102. The airflow flows downwards in a spiral shape along the inner spiral air guide groove 102, which guides the airflow to travel a longer downward distance. As the airflow flows downwards along the inner spiral air guide groove 102, its circumferential movement further expands the area of ​​influence. The upper connecting pipe 303 is connected to the carbonizing agent supply pipe. The carbonizing agent is connected to the carbonizing agent pipe 3 and the lower extension pipe 301 through the upper connecting pipe 303. The carbonizing agent flows outwards from the lower extension pipe 301. The air outlet pipe 401... As the airflow flows downwards, it carries the carburizing agent flowing out of the lower extension pipe 301 downwards, promoting the uniform distribution of the carburizing agent in the vertical direction inside the inner heat insulation furnace lining 101. As the airflow flows downwards along the inner spiral guide groove 102, its circumferential movement further expands the area of ​​influence, shortening the time required for the internal carbon potential atmosphere to become uniform, thus reducing the processing time and energy consumption of the carburizing furnace, achieving the goal of energy saving and emission reduction. When the inner spiral guide groove 102 guides the external airflow downwards, the airflow flows along the inner spiral guide groove 102 to the bottom and then moves upwards along the slope at the bottom. The lower air inlet of the internal circulation fan 4 and the inner air inlet of the outer isolation pipe 402 guide the airflow in the middle. As the internal heat insulation lining 101 moves upward, the airflow inside the internal spiral air guide groove 102 descends while the airflow in the middle of the inner carburizing boss 105 rises. The airflow is split and circulated. The external heat of the internal spiral air guide groove 102 quickly gathers and flows upward towards the part located on the upper part of the inner carburizing boss 105, accelerating the heating speed of the middle part. At the same time, during the process of the airflow gathering and flowing upward, the carburizing agent carried in the airflow comes into contact with the middle part, further accelerating the carburizing speed of the part, shortening the processing time of the carburizing furnace, making the carburizing of the part more efficient, and reducing the operating time and power consumption of the pit carburizing furnace.

[0043] Three horizontally spaced carburizing pipes 3 and a lower extension pipe 301 expand the horizontal carburizing agent discharge range. The threaded lifting rod 302 guides the lower extension pipe 301 to move axially, allowing it to penetrate deeper into the inner insulation lining 101. The lower extension pipe 301 is set at different heights to expand the carburizing agent range to different vertical depths, accelerating the carburizing agent diffusion efficiency and promoting uniform diffusion. After carburizing is complete, during the upward movement of the upper closed furnace cover 2, the outer telescopic insulation ring 203 will move upward under gravity. The extended outer telescopic heat insulation ring 203 extends to fit the top of the main carburizing furnace body 1. The outer telescopic heat insulation ring 203 isolates the flames escaping outward between the upper closed furnace cover 2 and the main carburizing furnace body 1, preventing the flames from escaping outward along the gap between the upper closed furnace cover 2 and the main carburizing furnace body 1 and endangering the surrounding personnel. After the gap between the upper closed furnace cover 2 and the main carburizing furnace body 1 expands to the point that the upper closed furnace cover 2 and the main carburizing furnace body 1 are completely separated, the flames will become vertical instead of spreading in all directions, which will have less impact on the surrounding personnel and improve the working environment of the staff.

[0044] The following points should be noted in this article:

[0045] 1. The accompanying drawings of the embodiments disclosed herein only relate to the structures involved in the embodiments disclosed herein; other structures can be referred to in general design.

[0046] 2. Where there is no conflict, the embodiments of this disclosure and the features in the embodiments can be combined with each other to obtain new embodiments.

[0047] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A high-efficiency and energy-saving pit-type carburizing furnace, comprising: The main carburizing furnace body (1), the upper closed furnace cover (2), the carburizing agent pipe (3), and the internal circulation fan (4) are characterized in that the top of the main carburizing furnace body (1) is fitted and sealed with the upper closed furnace cover (2), the upper part of the upper closed furnace cover (2) is fixedly provided with the carburizing agent pipe (3), the lower part of the upper closed furnace cover (2) is provided with the internal circulation fan (4), the inside of the main carburizing furnace body (1) is fixedly provided with the inner heat insulation furnace lining (101), the inner side of the inner heat insulation furnace lining (101) is provided with the inner spiral air guide groove (102), and the inner side of the inner heat insulation furnace lining (101) is fixed with the inner spiral heating element (103). (1) A lower sealing ring (104) is fixed on the outer side of the top. An inner carburizing boss (105) is provided on the bottom of the inner heat insulation furnace lining (101). The inner spiral air guide groove (102) of the inner heat insulation furnace lining (101) is recessed. The inner spiral air guide groove (102) and the inner spiral heating element (103) are staggered. The inner spiral air guide groove (102) and the inner spiral heating element (103) are both surrounded on the outer side of the inner carburizing boss (105). The airflow of the exhaust pipe (401) is guided downward by the inner spiral air guide groove (102). The airflow flows downward in a spiral shape along the inner spiral air guide groove (102).

2. The high-efficiency energy-saving pit-type carburizing furnace according to claim 1, characterized in that, The upper closed furnace cover (2) has a protruding lower boss frame (201) at the bottom, an upper sealing ring (202) is fixed at the bottom of the upper closed furnace cover (2), an outer telescopic heat insulation ring (203) is fixed on the outer side of the bottom of the upper closed furnace cover (2), and an exhaust pipe (204) is fixed through the upper closed furnace cover (2).

3. The high-efficiency and energy-saving pit-type carburizing furnace according to claim 2, characterized in that, The upper sealing ring (202) surrounds the outside of the lower boss (201), and the upper sealing ring (202) and the lower sealing ring (104) slide vertically and fit together for sealing. The outer telescopic heat insulation ring (203) surrounds the outside of the upper sealing ring (202), and the lower end of the exhaust pipe (204) extends to the bottom outside of the lower boss (201).

4. The high-efficiency energy-saving pit-type carburizing furnace according to claim 3, characterized in that, The lower end of the permeate tube (3) is slidably connected to a lower extension tube (301), and the lower extension tube (301) is screwed to a threaded lifting rod (302). The top end of the permeate tube (3) is connected to an upper connecting tube (303).

5. The high-efficiency energy-saving pit-type carburizing furnace according to claim 4, characterized in that, The three permeation pipes (3) connected by the upper connecting pipe (303) are arranged in an interval array. The lower extension pipe (301) and the lower boss (201) are axially slidably connected. The threaded lifting rod (302) and the upper closed furnace cover (2) are rotatably connected. The lower end of the lower extension pipe (301) extends to the outer side of the bottom of the lower boss (201).

6. The high-efficiency energy-saving pit-type carburizing furnace according to claim 1, characterized in that, The outer side of the internal circulation fan (4) is connected to the air outlet pipe (401), and the bottom of the internal circulation fan (4) is fixed with the lower air inlet external isolation pipe (402). The central fan blade of the internal circulation fan (4) and the main shaft of the upper drive motor (403) are fixed, and the upper drive motor (403) is fixed on the top of the upper closed furnace cover (2).

7. The high-efficiency energy-saving pit-type carburizing furnace according to claim 6, characterized in that, The exhaust pipe (401) is a ring-shaped curved pipe structure. The tail end of the exhaust pipe (401) faces the inner spiral air guide groove (102). The lower air inlet outer isolation pipe (402) surrounds the outside of the bottom inlet of the internal circulation fan (4). The lower air inlet outer isolation pipe (402) is located vertically above the inner carburized boss (105). The airflow of the exhaust pipe (401) is guided downward by the inner spiral air guide groove (102). The airflow flows downward in a spiral shape along the inner spiral air guide groove (102). The air inlet of the lower air inlet outer isolation pipe (402) of the internal circulation fan (4) guides the airflow in the middle to move upward. The airflow is split and circulated. The external heat of the inner spiral air guide groove (102) quickly gathers and flows upward towards the location of the components on the upper part of the inner carburized boss (105).

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