Carburizing furnace with atmosphere circulation structure

Abstract

The application discloses a carburizing furnace with an atmosphere circulation structure applied to the technical field of carburizing furnaces, which realizes bidirectional atmosphere circulation of carburizing gas through wind direction switching of a fan module, effectively improves the overall carburizing effect of workpieces, and realizes alternating support of workpieces through support pipes and lifting rings through lifting movement of a lower atmosphere bin driven by a lifting module, effectively reduces the time for the support pipes and the lifting rings to form contact shadows with the workpieces, and carburizing gas in the lower atmosphere bin is blown out from air holes and the support pipes, especially the carburizing gas blown out from the support pipes is directly aligned with the contact shadow area of the support pipes and the workpieces, so that the contact shadow area is alternately carburized and compensated, the carburizing processing effect of the contact shadow area of the workpieces is effectively improved, and the uniformity of overall carburizing of the workpieces is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of carburizing furnace technology, and in particular to a carburizing furnace with an atmosphere circulation structure. Background Technology

[0002] Because mechanical parts need to withstand strong friction, impact and alternating stress during operation, they need to be carburized to improve their structural strength. The core purpose of carburizing is to significantly improve the surface hardness, wear resistance and fatigue strength of steel parts, while maintaining good toughness and plasticity in their core.

[0003] The atmosphere circulation within the carburizing furnace is a crucial factor determining the carburizing quality of mechanical parts. This is primarily achieved through a specially designed fan system and a furnace structure that guides airflow, such as the pit-type carburizing furnace disclosed in Chinese Patent CN215560596U. Furthermore, during the carburizing process, mechanical parts require an overhead support structure to allow the carburizing gas to fully envelop them, as in the low-temperature ion carburizing furnace disclosed in Chinese Patent CN222043328U. However, the contact between the support structure and the mechanical parts creates a contact shadow. This shadow area affects the contact between the carburizing atmosphere and the mechanical parts, potentially impacting the overall uniformity of carburizing and consequently affecting the quality of the carburizing process. Summary of the Invention

[0004] 1. Technical problems to be solved

[0005] The core of this invention lies in the alternating support of the workpiece by the support tube and the lifting ring, thereby effectively reducing the time for the support tube and the lifting ring to form a contact shadow with the workpiece. This solves the problem in the prior art where the contact shadow area affects the contact between the carburizing atmosphere and the mechanical parts, thus affecting the carburizing quality of the mechanical parts.

[0006] 2. Technical Solution

[0007] To solve the above problems, the present invention adopts the following technical solution.

[0008] A carburizing furnace with an atmosphere circulation structure includes a furnace body, a conveying track fixedly connected to the bottom of the furnace body, a carrier plate slidably connected to the top of the conveying track, a workpiece placed on the top of the carrier plate, a lifting module fixedly connected to the bottom of one end of the furnace body, a lower atmosphere chamber fixedly connected to the output end of the lifting module, the lower atmosphere chamber being located at the bottom of the conveying track, an upper atmosphere chamber fixedly connected to the top of one end of the furnace body, guide channels fixedly connected to the bottom of both ends of the upper atmosphere chamber, the bottom ends of the guide channels being inserted into the lower atmosphere chamber, a circulation window opened in the middle of the bottom end of the upper atmosphere chamber, an air hole opened in the top of the lower atmosphere chamber, and a fan module fixedly connected inside the circulation window, the fan module being configured as a bidirectional fan;

[0009] The top of the carrier tray has evenly spaced connecting holes, and a support ring is fixedly connected to the upper opening of the connecting holes. The top of the lower air chamber is fixedly connected to a support tube, which passes through the connecting holes. The top of the support tube and the top of the support ring alternately support and contact the lower surface of the workpiece.

[0010] Optionally, a movable chamber is provided on the inner wall of the lower opening of the vent, and a sealing plug is inserted into the movable chamber to block the vent. Both the sealing plug and the movable chamber are conical in shape.

[0011] Furthermore, the outer wall of the conveying track is fixedly connected with a fixing pile, which extends through into the interior of the lower atmosphere chamber, and the bottom of the fixing pile is fixedly connected with a fixing support plate, and the bottom end of the sealing plug is fixedly connected to the fixing support plate.

[0012] Optionally, a tube cavity chamber is formed on the inner wall of the top end of the support tube, and an edge groove is formed on the top edge of the tube cavity chamber, which connects the outer wall and the inner wall of the support tube.

[0013] Furthermore, an air cover is movable inside the oral cavity chamber, and a limit cover ring is fixedly connected to the top of the oral cavity chamber. The air cover and the limit cover ring are inserted into each other.

[0014] Furthermore, the inner wall of the oral cavity is fixedly connected to a guide rail, and a guide groove is provided at the bottom edge of the air cover, with the guide groove slidably connected to the guide rail.

[0015] Furthermore, a pin is fixedly connected to the top center of the cover, and the tip of the pin is in contact with the workpiece.

[0016] Furthermore, an expansion groove is provided on the bottom inner wall of the oral cavity, and the distance between the expansion groove and the top of the support tube is less than the length of the ejector pin.

[0017] 3. Beneficial Effects

[0018] Compared with the prior art, the advantages of this invention are:

[0019] (1) This solution achieves bidirectional atmosphere circulation of carburizing gas by switching the air direction of the fan module, which effectively improves the overall carburizing effect of the workpiece. Furthermore, the workpiece is alternately supported by the support tube and the lifting ring, thereby effectively reducing the time when the support tube and the lifting ring form a contact shadow with the workpiece. The two contact shadow areas are alternately carburized to compensate for the contact shadow areas, which effectively improves the carburizing effect of the contact shadow areas of the workpiece, and thus effectively improves the uniformity of the overall carburizing of the workpiece.

[0020] (2) When the support tube and the lifting ring alternately support the workpiece, the degree of the sealing plug extending into the sealing hole is adjusted synchronously, the flow rate of the carburizing gas discharged from the hole is adjusted, and the flow rate of the carburizing gas discharged from the support tube is indirectly adjusted. When the lifting ring supports the workpiece, more carburizing gas is blown out from the support tube, and the carburizing compensation treatment is mainly carried out on the contact shadow area between the support tube and the workpiece.

[0021] (3) By combining the air cover and the ejector pin, the support tube is distinguished. The air cover and the limiting cover ring are inserted and connected to close the support tube that does not support the workpiece. The support tube that supports the workpiece is prevented from rising further by the ejector pin against the workpiece and is inserted and connected to the limiting cover ring. The tube cavity still retains the flow space, and the flow space is increased by the expansion groove, which effectively improves the concentration of carburizing gas and enables more carburizing gas to act on the contact shadow area between the support tube and the workpiece. Attached Figure Description

[0022] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0023] Figure 2 This is a three-dimensional demonstration diagram of the operation of removing the workpiece from the furnace body according to the present invention;

[0024] Figure 3 This is a cross-sectional view of the lower atmosphere chamber and the upper atmosphere chamber of the present invention;

[0025] Figure 4 This is a three-dimensional structural diagram of the lower atmosphere chamber and the upper atmosphere chamber of the present invention;

[0026] Figure 5 This is a three-dimensional structural diagram of the carrier disk and the workpiece of the present invention;

[0027] Figure 6 This is a three-dimensional structural diagram of the atmosphere chamber, carrier plate, and workpiece in the present invention.

[0028] Figure 7 This is an enlarged view of the workpiece being supported by the support tube of the present invention;

[0029] Figure 8 This is an enlarged view of the workpiece supported by the lifting ring of the present invention;

[0030] Figure 9 This is a cross-sectional view of the movable chamber and the sealing plug of the present invention;

[0031] Figure 10 This is a bottom-view perspective structural diagram of the movable chamber and sealing plug of the present invention;

[0032] Figure 11 This is a top perspective view of the sealing plug of the present invention;

[0033] Figure 12This is a three-dimensional enlarged view of the support tube of the present invention;

[0034] Figure 13 This is a three-dimensional cross-sectional view of the oral cavity of the present invention;

[0035] Figure 14 This is an exploded three-dimensional structural diagram of the oral cavity, air cover, and limiting cover ring of the present invention;

[0036] Figure 15 This is a demonstration diagram showing the air cover and the limiting cover ring of the present invention being joined together under the push of carburizing gas;

[0037] Figure 16 This is a demonstration diagram of the carburizing gas being blown out when the support tube of the present invention is supporting the workpiece;

[0038] Figure 17 This is a demonstration diagram of the carburizing gas being blown out when the support tube is lowered and adjusted to allow the workpiece to be unsupported.

[0039] Explanation of the labels in the diagram:

[0040] 1 Furnace body, 101 Conveying rail, 102 Carrier tray, 103 Workpiece, 2 Lifting module, 201 Lower atmosphere chamber, 202 Upper atmosphere chamber, 203 Guide channel, 204 Circulation window, 205 Air hole, 206 Fan module, 3 Connecting hole, 301 Lifting ring, 302 Support tube, 4 Movable chamber, 401 Sealing plug, 402 Fixing pile, 403 Fixing bracket plate, 5 Tube cavity chamber, 501 Edge groove, 502 Air cover, 503 Limiting cover ring, 504 Guide rail, 505 Guide groove, 506 Ejector pin, 507 Expansion groove. Detailed Implementation

[0041] The technical solutions will now be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention.

[0042] Example 1:

[0043] Please refer to a carburizing furnace with an atmosphere circulation structure. Figures 1 to 4 The furnace includes a furnace body 1, with a conveying track 101 fixedly connected to the bottom of the furnace body 1 and a carrier plate 102 slidably connected to the top of the conveying track 101. A workpiece 103 is placed on the top of the carrier plate 102. When using the carburizing furnace, the workpiece 103 to be processed is placed on the carrier plate 102 and then transported through the conveying track 101 so that the workpiece 103 enters the carburizing processing area inside the furnace body 1.

[0044] The lower atmosphere chamber 201 is located at the bottom of the conveying track 101. The upper atmosphere chamber 202 is fixedly connected to the top of one end of the furnace body 1. Both ends of the upper atmosphere chamber 202 are fixedly connected to the bottom of the upper atmosphere chamber 202. The guide channel 203 allows the carburizing gas to flow smoothly between the lower atmosphere chamber 201 and the upper atmosphere chamber 202. The bottom end of the guide channel 203 is inserted into the lower atmosphere chamber 201. A circulation window 204 is opened in the middle of the bottom end of the upper atmosphere chamber 202. An air hole 205 is opened in the top of the lower atmosphere chamber 201. A fan module 206 is fixedly connected inside the circulation window 204. The fan module 206 is set as a bidirectional fan. The fan module 206 provides the power for the flow of carburizing gas, effectively improving the atmosphere circulation efficiency in the furnace body 1.

[0045] When the workpiece 103 is being carburized, the fan module 206 first switches to the state of blowing out the carburizing gas in the upper atmosphere chamber 202. The carburizing gas is blown from top to bottom toward the workpiece 103, which effectively improves the carburizing effect on the upper part of the workpiece 103. Then the carburizing gas enters the lower atmosphere chamber 201 through the air hole 205, and finally returns to the upper atmosphere chamber 202 through the guide channel 203, realizing the circulation of the carburizing gas.

[0046] The fan module 206 then switches to the state of drawing carburizing gas into the upper atmosphere chamber 202. The carburizing gas is first sent to the lower atmosphere chamber 201 through the guide channel 203. The carburizing gas is blown out from the air hole 205 from bottom to top, so that the carburizing gas comes into contact with the workpiece 103, effectively improving the carburizing effect of the lower part of the workpiece 103. Finally, the carburizing gas is drawn into the upper atmosphere chamber 202 by the fan module 206 to realize the circulation of carburizing gas.

[0047] By switching the airflow direction of the fan module 206, a two-way atmosphere circulation of carburizing gas is achieved, effectively improving the overall carburizing effect of the workpiece 103.

[0048] Please see Figures 5 to 8 The top of the carrier plate 102 is evenly provided with connecting holes 3. The upper opening of the connecting hole 3 is fixedly connected to the lifting ring 301. The top of the lower atmosphere chamber 201 is fixedly connected to the support tube 302. The support tube 302 passes through the connecting hole 3, and the top of the support tube 302 and the top of the lifting ring 301 alternately support and contact the lower surface of the workpiece 103. When the workpiece 103 is placed on the carrier plate 102, the lifting ring 301 provides support for the workpiece 103. The support tube 302 rises and passes through the connecting hole 3, and the workpiece 103 is lifted by the support tube 302, so that the workpiece 103 leaves the lifting ring 301. A lifting module 2 is fixedly connected to the bottom of one end of the furnace body 1. The output end of the lifting module 2 is fixedly connected to the lower atmosphere chamber 201. The lifting module 2 drives the lifting adjustment of the lower atmosphere chamber 201, so that the support tube 302 rises and lifts the workpiece 103.

[0049] When the workpiece 103 carried by the carrier plate 102 moves to the processing area of ​​the furnace body 1, the lifting module 2 drives the lower atmosphere chamber 201 to rise, so that the support tube 302 passes through the connecting hole 3, thereby locking the state of the carrier plate 102 and effectively improving the stability of the workpiece 103 on the carrier plate 102.

[0050] When the workpiece 103 is being carburized at the bottom (the carburizing gas circulates from bottom to top), the lifting module 2 drives the lower atmosphere chamber 201 to rise. The support tube 302 at the top of the lower atmosphere chamber 201 passes through the connecting hole 3. The support tube 302 is connected to the lifting ring 301 to provide support for the workpiece 103. Specifically, the workpiece 103 is supported by the support tube 302, so that the workpiece 103 is removed from the lifting ring 301.

[0051] After a period of carburizing, the lifting module 2 drives the lower atmosphere chamber 201 to descend, so that the top of the support tube 302 is lower than the lifting ring 301. The descending support tube 302 does not detach from the connecting hole 3, and continues to keep the carrier plate 102 locked. The lifting ring 301 takes over the support tube 302 to provide support for the workpiece 103, and the workpiece 103 detaches from the support tube 302.

[0052] The workpiece 103 is alternately supported by the support tube 302 and the lifting ring 301, thereby effectively reducing the time when the support tube 302 and the lifting ring 301 form a contact shadow with the workpiece 103. Furthermore, the two contact shadow areas are alternately carburized to compensate for the contact shadow areas, which effectively improves the carburizing effect of the contact shadow areas of the workpiece 103, and thus effectively improves the uniformity of the overall carburizing of the workpiece.

[0053] Example 2:

[0054] Compared to Example 1, the main additions are a movable chamber 4 and a sealing plug 401. The specific additions are as follows, while the rest of the structure is the same as in Example 1.

[0055] Please see Figures 9 to 11 A movable chamber 4 is provided on the inner wall of the lower opening of the vent 205. A sealing plug 401 is inserted into the movable chamber 4. The sealing plug 401 is used to seal the vent 205. Both the sealing plug 401 and the movable chamber 4 are conical. The flow space of the vent 205 is controlled according to the extent to which the sealing plug 401 extends into the vent 205, thereby adjusting the air flow rate of the vent 205. A fixed pile 402 is fixedly connected to the outer wall of the conveying track 101. The fixed pile 402 extends through into the interior of the lower atmosphere chamber 201. A fixed support plate 403 is fixedly connected to the bottom of the fixed pile 402. The bottom end of the sealing plug 401 is fixedly connected to the fixed support plate 403. The lower atmosphere chamber 201 moves up and down driven by the lifting module 2, so that the sealing plug 401 can move synchronously within the vent 205.

[0056] When the lower atmosphere chamber 201 moves up and down driven by the lifting module 2, the support tube 302 and the lifting ring 301 alternately support the workpiece 103. Specifically, when the lower atmosphere chamber 201 drives the support tube 302 to rise and support the workpiece 103, the movable chamber 4 rises away from the sealing plug 401, increasing the flow space of the vent 205 and increasing the carburizing gas discharge flow rate of the vent 205 (when the support tube 302 supports the workpiece 103, the opening space of the support tube 302 decreases, and the carburizing gas discharge flow rate of the support tube 302 decreases). When the lower atmosphere chamber 201 drives the support tube 302 to fall away from the workpiece 103, the lifting ring 301 supports the workpiece 103. At this time, the movable chamber 4 falls closer to the sealing plug 401, reducing the flow space of the vent 205 and decreasing the carburizing gas discharge flow rate of the vent 205. This relatively increases the carburizing gas discharge flow rate of the support tube 302. The focus is on carburizing compensation treatment of the contact shadow area between the support tube 302 and the workpiece 103.

[0057] Compared to Example 1, under the lifting module 2, the atmosphere chamber 201 moves up and down. When the workpiece 103 is alternately supported by the support tube 302 and the lifting ring 301, the degree to which the sealing plug 401 extends into the sealing vent 205 is adjusted, and the flow rate of the carburizing gas discharged from the vent 205 is adjusted. This indirectly adjusts the flow rate of the carburizing gas discharged from the support tube 302. When the lifting ring 301 supports the workpiece 103, more carburizing gas is blown out from the support tube 302, and the carburizing compensation treatment is mainly carried out on the contact shadow area between the support tube 302 and the workpiece 103.

[0058] Example 3:

[0059] Compared to Example 1, the main addition is a wind cover 502, the specific addition structure is as follows, and the rest of the structure is the same as Example 1.

[0060] Please see Figures 12 to 17The inner wall of the top end of the support tube 302 is provided with a tube cavity chamber 5. An edge groove 501 is provided at the top edge of the tube cavity chamber 5, connecting the outer and inner walls of the support tube 302. When the top end of the support tube 302 contacts the workpiece 103, the carburizing gas flowing inside the support tube 302 is discharged outwards through the edge groove 501. An air cover 502 is movably placed inside the tube cavity chamber 5, and a limiting cover ring 503 is fixedly connected to the top end of the tube cavity chamber 5. The air cover 502 and the limiting cover ring 503... 3. Insertion: The carburizing gas inside the support tube 302 blows the air cover 502 upward, causing the air cover 502 to insert and engage with the limiting cover ring 503, thereby sealing the tube cavity chamber 5 and effectively preventing the carburizing gas from escaping from the top of the support tube 302 (this obstruction function mainly acts on the support tube 302 that does not support the workpiece 103, i.e., the support tube 302 that is misaligned with the workpiece 103). The inner wall of the tube cavity chamber 5 is fixedly connected to the guide rail 504, and the bottom edge of the air cover 502 is provided with a guide groove. 505, the guide groove 505 is slidably connected to the guide rail 504, and the air cover 502 slides on the guide rail 504 through the guide groove 505, effectively improving the lifting stability of the air cover 502. A pin 506 is fixedly connected to the top center of the air cover 502, and the top of the pin 506 abuts against the workpiece 103. An expansion groove 507 is opened on the bottom inner wall of the tube cavity chamber 5. The distance between the expansion groove 507 and the top of the support tube 302 is less than the length of the pin 506, and the seepage in the support tube 302 is... When the carbon gas blows the air cover 502 upward, the ejector pin 506 contacts the workpiece 103 to prevent the air cover 502 from continuing to rise. This ensures that the carburizing gas in the support tube 302, which supports the workpiece 103, can still be discharged after it descends. By clearly setting the length of the ejector pin 506, as long as the ejector pin 506 is blocked by the workpiece 103, the air cover 502 can be positioned in the expansion groove 507, increasing the flow space of the carburizing gas and further increasing the discharge flow rate of the carburizing gas.

[0061] like Figure 16 As shown in the figure, the arrows indicate the flow path of the carburizing gas. When the workpiece 103 is supported at the top of the support tube 302, the carburizing gas flowing in the support tube 302 is discharged outward from the edge groove 501. The discharged carburizing gas can be guided to approach the contact shadow area between the support ring 301 and the workpiece 103.

[0062] like Figure 15 As shown in the figure, the arrows indicate the flow path of the carburizing gas. The carburizing gas in the support tube 302, which does not support the workpiece 103, blows the air cover 502 upward, causing the air cover 502 to be inserted and connected with the limiting cover ring 503, thereby sealing the tube cavity chamber 5 and effectively preventing the carburizing gas from being discharged from the top of the support tube 302. This allows more carburizing gas to be discharged from the support tube 302 that supports the workpiece 103, effectively improving the concentration of the carburizing gas.

[0063] like Figure 17 As shown in the figure, the arrows indicate the flow path of the carburizing gas. After the support tube 302, which supports the workpiece 103, moves downward, the carburizing gas inside it also blows the air cover 502 upward. The air cover 502 is prevented from rising further by contacting the workpiece 103 through the ejector pin 506, and the air cover 502 is positioned in the expansion groove 507. The flow space of the carburizing gas is increased, which effectively improves the discharge flow rate of the carburizing gas from the support tube 302.

[0064] Compared to Example 1, the distinction is made based on whether the support tube 302 is used to support the workpiece 103. In the example where the support tube 302 does not perform a supporting function, there is a spatial misalignment between it and the workpiece 103. When the carburizing gas inside the support tube 302 is discharged outwards, such as... Figure 15 As shown, the air cover 502 rises under the action of the carburizing gas wind force, and because the upper space of the support tube 302 is open, the rise of the ejector pin 506 is unrestricted, so that the air cover 502 and the limiting cover ring 503 are inserted and combined to achieve the sealing of the tube cavity chamber 5, effectively preventing the carburizing gas from being discharged from the top of the support tube 302, so that the carburizing atmosphere will not overflow from there, and thus the support tube 302 corresponding to the workpiece 103 can concentrate the overflow of the carburizing atmosphere and act on the workpiece 103, effectively improving the utilization rate of the carburizing gas.

[0065] The support tube 302 used to support the workpiece 103, in both the supported state and the lowering adjustment state, such as Figure 16 and Figure 17 As shown, the carburizing gas inside also blows the air cover 502 upward, and the air cover 502 is prevented from rising further by contacting the workpiece 103 through the ejector pin 506. The flow space is still maintained in the tube cavity chamber 5, and the flow space is increased by the expansion groove 507. That is, the air cover 502 is always in the area of ​​the expansion groove 507, and the carburizing gas can bypass the edge of the air cover 502 to flow, so that more carburizing gas can act on the contact shadow area between the support tube 302 and the workpiece 103, effectively improving the carburizing uniformity of the contact shadow area between the support tube 302 and the workpiece 103.

[0066] The above description is merely a preferred embodiment of the present invention; it encompasses all the protection scope of the present invention. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solutions and improved concepts of the present invention, should be covered within the protection scope of the present invention.

Claims

1. A carburizing furnace with an atmosphere circulation structure, comprising a furnace body (1), wherein a conveying track (101) is fixedly connected to the bottom of the furnace body (1), a carrier plate (102) is slidably connected to the top of the conveying track (101), and a workpiece (103) is placed on the top of the carrier plate (102), characterized in that: A lifting module (2) is fixedly connected to the bottom of one end of the furnace body (1). The output end of the lifting module (2) is fixedly connected to a lower atmosphere chamber (201). The lower atmosphere chamber (201) is located at the bottom of the conveying track (101). An upper atmosphere chamber (202) is fixedly connected to the top of one end of the furnace body (1). A guide channel (203) is fixedly connected to the bottom of both ends of the upper atmosphere chamber (202). The bottom end of the guide channel (203) is inserted into the lower atmosphere chamber (201). A circulation window (204) is opened in the middle of the bottom end of the upper atmosphere chamber (202). An air hole (205) is opened at the top of the lower atmosphere chamber (201). A fan module (206) is fixedly connected inside the circulation window (204). The fan module (206) is set as a bidirectional fan. The top of the carrier plate (102) is uniformly provided with connecting holes (3), and a support ring (301) is fixedly connected to the upper opening of the connecting hole (3). The top of the lower atmosphere chamber (201) is fixedly connected with a support tube (302). The support tube (302) passes through the connecting hole (3), and the top of the support tube (302) and the top of the support ring (301) alternately support and contact the lower surface of the workpiece (103).

2. A carburizing furnace with an atmosphere circulation structure according to claim 1, characterized in that: The lower part of the air hole (205) has an openable chamber (4) on its inner wall. A sealing plug (401) is inserted into the interior of the openable chamber (4). The sealing plug (401) is used to block the air hole (205). Both the sealing plug (401) and the openable chamber (4) are conical in shape.

3. A carburizing furnace with an atmosphere circulation structure according to claim 2, characterized in that: The outer wall of the conveying track (101) is fixedly connected to a fixed pile (402), the fixed pile (402) extends through into the interior of the lower atmosphere chamber (201), and the bottom of the fixed pile (402) is fixedly connected to a fixed support plate (403), and the bottom end of the sealing plug (401) is fixedly connected to the fixed support plate (403).

4. A carburizing furnace with an atmosphere circulation structure according to claim 1, characterized in that: The top end of the support tube (302) has a tube cavity chamber (5) on its inner wall, and the top edge of the tube cavity chamber (5) has an edge groove (501) that connects the outer wall and the inner wall of the support tube (302).

5. A carburizing furnace with an atmosphere circulation structure according to claim 4, characterized in that: An air cover (502) is movably placed inside the oral cavity chamber (5), and a limiting cover ring (503) is fixedly connected to the top of the oral cavity chamber (5). The air cover (502) and the limiting cover ring (503) are inserted into each other.

6. A carburizing furnace with an atmosphere circulation structure according to claim 5, characterized in that: The inner wall of the oral cavity (5) is fixedly connected to a guide rail (504), and the bottom edge of the air cover (502) is provided with a guide groove (505), which is slidably connected to the guide rail (504).

7. A carburizing furnace with an atmosphere circulation structure according to claim 6, characterized in that: A pin (506) is fixedly connected to the middle of the top of the cover (502), and the top of the pin (506) is in contact with the workpiece (103).

8. A carburizing furnace with an atmosphere circulation structure according to claim 7, characterized in that: The bottom inner wall of the oral cavity (5) is provided with an expansion groove (507), and the distance between the expansion groove (507) and the top end of the support tube (302) is less than the length of the ejector pin (506).

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