Hot wall type carburizing furnace structure and uniform carburizing method

Abstract

The invention discloses a hot wall type carburizing furnace structure and a uniform carburizing method, and belongs to the technical field of heat treatment equipment. Comprising a carburizing skip car, a vacuum sealing door used for separating a cooling chamber from a carburizing chamber and a heating chamber door, a carrying track in the carburizing chamber extends to a track exhaust port below the heating chamber door and can be communicated with the carburizing chamber and the cooling chamber, the temperature in the carburizing chamber can be increased and kept constant through a heater, and the cooling chamber can exhaust in a vacuum mode. A plurality of first supply ports are formed in the middle of the longitudinal tail end, away from the heating chamber door, in the carburizing chamber, carburizing gas introduced into the carburizing chamber through the first supply ports is sprayed in a radial mode, and a plurality of second supply ports are formed in the two transverse sides of the carburizing chamber and arranged in a high-low staggered mode. According to the hot wall type carburizing furnace structure and the uniform carburizing method, the problem that carburizing differentiation of treated parts is obvious due to immobilization of a gas circulation path and high-density charging of the treated parts of a carburizing furnace with a single exhaust structure is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of heat treatment equipment, and particularly relates to a hot-wall type carburizing furnace structure and a uniform carburizing method. BACKGROUND

[0002] Unlike the atmosphere carburizing method, the vacuum carburizing method is a heat treatment process for realizing carburizing through decomposition of carbon-hydrogen gas (such as acetylene, propane) in a low-pressure environment (usually ≤ 3 kPa), and can avoid the problem of workpiece oxidation from the root. However, the atmosphere carburizing method can ensure the uniformity of workpiece carburizing through the gas stirring device in the atmosphere furnace, while in the low-pressure environment in the carburizing furnace, due to the significant reduction in gas molecular density and the significant increase in molecular free path, the existing gas stirring device is usually difficult to function, which leads to the problem of uneven distribution of carburizing gas concentration in the existing carburizing furnace.

[0003] At the same time, for the existing carburizing furnace with a single exhaust structure (such as unable to increase or decrease the exhaust port, only relying on the conveying slide rail to exhaust), when acetylene is used as carbon-hydrogen gas for vacuum carburizing operation, the hydrogen gas generated by the decomposition of acetylene will accumulate in the position far from the carburizing gas supply port in the carburizing furnace, and the increase in hydrogen concentration will inhibit the generation and adsorption of active carbon atoms. At the same time, based on the problem of fixed gas flow path of the single exhaust structure, this leads to the existence of high-concentration carburizing gas that cannot be supplied to the area with high hydrogen concentration accumulation in the carburizing chamber. Therefore, between the area where high-concentration carburizing gas is always supplied and the area where high-concentration carburizing gas is not easily supplied, the carbon concentration and carburizing depth on the surface of the workpiece will be significantly different, and this problem is more obvious when the carburizing furnace is long in depth and the workpieces are high in density. SUMMARY

[0004] The purpose of the present application is to overcome the deficiencies in the prior art, and to provide a hot-wall type carburizing furnace structure and a uniform carburizing method, which solves the problem of obvious carburizing differentiation of the workpiece in the carburizing furnace with a single exhaust structure due to the fixed gas flow path and high-density loading of the workpiece by adding a first supply port that can radiate carburizing gas into the carburizing chamber at the longitudinal end of the carburizing chamber, and optimizing the supply position of the second supply port in the carburizing chamber.

[0005] In order to achieve the above object, the technical scheme adopted by the present application is: a hot-wall type carburizing furnace structure, comprising a vacuum sealing door for separating a cooling chamber and a carburizing chamber, a heating chamber door, a carrying track for a carburizing trolley walking for placing processing pieces is reserved in the middle of the hearth of the carburizing chamber, and the carrying track extends to a track exhaust port below the heating chamber door to enable the carburizing chamber and the cooling chamber to be communicated, the carburizing chamber can be heated and kept constant temperature by a heater, the cooling chamber can be vacuum exhausted and can be communicated with the external environment through a front door, a plurality of first supply ports communicated with carburizing gas are arranged in the middle of the longitudinal end of the carburizing chamber away from the heating chamber door, the carburizing gas in the plurality of first supply ports is injected radially into the carburizing chamber, a plurality of second supply ports communicated with carburizing gas are arranged on the left and right sides of the carburizing chamber from the longitudinal end to the heating chamber door, and the plurality of second supply ports are arranged in high and low staggered manner.

[0006] Optionally, the plurality of second supply ports are divided into two groups, and the two groups of second supply ports are arranged in the front half of the carburizing chamber close to the heating chamber door and the rear half close to the first supply port, respectively, and the two groups of second supply ports are arranged on the left and right sides of the carburizing chamber, respectively; Each group of second supply ports is arranged in two parallel rows, and each row of second supply ports is distributed along the longitudinal direction of the carburizing chamber in a straight line and arranged uniformly. One group of second supply ports in the front half of the carburizing chamber are higher than the first supply ports, and one group of second supply ports in the rear half of the carburizing chamber are lower than the first supply ports.

[0007] Optionally, the first supply port extends into the carburizing chamber through a gas guide pipe arranged along the longitudinal direction of the carburizing chamber, one end of the gas guide pipe arranged in the carburizing chamber is closed, and a plurality of gas guide holes are arranged along the radial direction of the outer periphery of the one end of the gas guide pipe arranged in the carburizing chamber.

[0008] Optionally, an oil tank for quenching is arranged at the bottom of the cooling chamber, and a lifting platform for carrying the carburizing trolley and capable of vertical lifting is arranged in the cooling chamber; The carburizing trolley can be lowered to be immersed in the oil tank together with the lifting platform, the carburizing trolley can be raised to be docked with the carrying track and / or the front door together with the lifting platform, and when the lifting platform is raised to be docked with the carrying track, the carburizing trolley can walk along the carrying track into the carburizing chamber.

[0009] A uniform carburizing method is realized by using the aforementioned hot-wall type carburizing furnace structure, comprising the following steps: S1, open the front door, vacuum sealing door, heating chamber door, and send the carburizing trolley with uniformly arranged treatment pieces into the cooling chamber, and then close the front door; S2, start the vacuum exhaust of the cooling chamber, and exhaust the air in the cooling chamber and the carburizing chamber until the vacuum degree in the cooling chamber and the carburizing chamber reaches a predetermined value; S3, transfer the carburizing trolley to the carburizing chamber, then close the vacuum sealing door and the heating chamber door, and preheat the treatment pieces in the carburizing chamber until the temperature of the treatment pieces is preheated to a preset carburizing temperature range; S4, after the preheating of the treatment pieces is completed, the temperature in the carburizing chamber is maintained in the preset carburizing temperature range, and the treatment pieces are carburized for a set carburizing time, during which the vacuum exhaust is periodically started and stopped, and the first supply port and the second supply port periodically introduce high-concentration carburizing gas into the carburizing chamber at a predetermined flow rate; S5, after the set carburizing time is over, the supply of high-concentration carburizing gas is cut off, and the vacuum exhaust is continuously performed, during which the temperature in the carburizing chamber is maintained in the preset carburizing temperature range for a period of time, and then is cooled to a quenching temperature and maintained for a period of time, so that all the treatment pieces reach the quenching temperature; S6, after the treatment pieces reach the quenching temperature, the heating chamber door and the vacuum sealing door are opened, and the treatment pieces are transferred to the oil tank for quenching. After the quenching of the treatment pieces is completed, the oil is drained, and the cooling chamber is pressurized to the atmospheric pressure. Finally, the front door is opened, and the treatment pieces are transferred.

[0010] Optionally, after the heating chamber door and the vacuum sealing door are opened and before the treatment pieces are transferred to the oil tank for quenching, the heating chamber door and the vacuum sealing door are closed.

[0011] Optionally, the preset carburizing temperature is 800-1050℃.

[0012] Optionally, the quenching temperature is 800-870℃.

[0013] Compared with the prior art, the present application has the following beneficial effects: (1) By adding the first supply port at the longitudinal end of the carburizing chamber, the carburizing gas introduced into the carburizing chamber by the first supply port can be sprayed in a radial manner, so that the radiation range of the carburizing gas sprayed by the first supply port can cover the longitudinal end of the carburizing chamber, thereby avoiding the situation that the treatment pieces placed at the longitudinal end of the carburizing chamber have relatively low surface carbon concentration and carburizing depth due to the ineffective supply of high-concentration carburizing gas. At the same time, by optimizing the supply position of the second supply port in the carburizing chamber, the second supply ports are arranged in a staggered manner, thereby avoiding the situation that the carburizing gas concentration in the local position of the carburizing chamber is too high or too low, and reducing the surface carburizing difference of the treatment pieces arranged at different positions on the carburizing trolley; (2) By periodically opening and closing the vacuum exhaust, the fixed path of gas flow can be broken, so that the high concentration of carburizing gas can be passively diffused, thereby increasing the concentration of carburizing gas on both sides of the lower front end of the track exhaust port, and reducing the surface carburizing differences caused by uneven distribution of carburizing concentration. BRIEF DESCRIPTION OF DRAWINGS

[0014] The application will be further described below in conjunction with the drawings and examples.

[0015] Figure 1 is a schematic diagram of the structure of the hot-wall type carburizing furnace in the preferred embodiment of the application; Figure 2 is a schematic diagram of the structure of the track exhaust port in the preferred embodiment of the application; Figure 3 is a schematic diagram of the structure of the gas guide pipe in the preferred embodiment of the application; Figure 4 is a schematic diagram of the space distribution of the first supply port, the second supply port, and the track exhaust port in the carburizing chamber in the preferred embodiment of the application; Figure 3 is a schematic diagram of the cross-sectional structure at A-A; Figure 5 is a schematic diagram of the space distribution of the first supply port, the second supply port, and the track exhaust port in the carburizing chamber in the preferred embodiment of the application; Figure 6 is a schematic diagram of the space distribution of the sample points in the preferred embodiment of the application; Figure 7 is a hardness-carburizing depth data graph of the sample after carburizing operation using only the second supply port to supply carburizing gas in the preferred embodiment of the application; Figure 8 is a corresponding part of the sample surface carbon concentration data graph in the preferred embodiment of the application; Figure 6 is a hardness-carburizing depth data graph of the sample after carburizing operation using only the first supply port to supply carburizing gas in the preferred embodiment of the application; Figure 9 is a corresponding part of the sample surface carbon concentration data graph in the preferred embodiment of the application; Figure 10 Figure 9 is a hardness-carburizing depth data graph of the sample after carburizing operation using the first supply port and the second supply port to supply carburizing gas in the preferred embodiment of the application; Figure 11 is a corresponding part of the sample surface carbon concentration data graph in the preferred embodiment of the application; Figure 12 is a corresponding part of the sample surface carbon concentration data graph in the preferred embodiment of the application; Figure 11 ​​Wherein, 1, cooling chamber; 2, carburizing chamber; 3, vacuum sealing door; 4, heating chamber door; 5, carburizing trolley; 6, carrying track; 7, track exhaust port; 8, front door; 9, first supply port; 10, second supply port; 11, gas guide pipe; 1101, gas guide hole; 13, oil groove; 14, lifting platform. DETAILED DESCRIPTION

[0016] The present application will now be described in further detail by examples in conjunction with the accompanying drawings, which are simplified schematic diagrams and merely show the basic structure of the present application in a schematic manner, and thus, only show the components related to the present application.

[0017] It should be noted that if the present embodiment involves directional indications (such as up, down, bottom, top, etc.), the directional indications are only used to explain the relative positional relationship, movement, etc. between the components in a certain specific posture, and if the specific posture changes, the directional indications also change accordingly. The terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features with "first", "second" can explicitly or implicitly include one or more of the features. Unless otherwise specified and limited, the terms "set", "connected", "connected" should be broadly understood, for example, it can be fixedly connected, or detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium; it can be the communication between the two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. Example one

[0018] As Figures 1-5As shown, a hot-wall type carburizing furnace structure includes a vacuum sealing door 3 for separating the cooling chamber 1 and the carburizing chamber 2, a heating chamber door 4, a handling track 6 is reserved in the middle of the hearth of the carburizing chamber 2 for the carburizing trolley 5 to walk, and the handling track 6 extends to the track exhaust port 7 below the heating chamber door 4 to enable the carburizing chamber 2 to communicate with the cooling chamber 1, that is, when the vacuum sealing door 3 and / or the heating chamber door 4 is closed, the track exhaust port 7 can become the only exhaust structure between the carburizing chamber 2 and the cooling chamber 1, and the exhaust structure is located at the middle position of the lower end of the longitudinal direction of the carburizing chamber 2 (the carburizing chamber 2 is in a strip shape, and the longitudinal direction of the carburizing chamber 2 refers to the length extension direction of the carburizing chamber 2 in this technical solution). The carburizing chamber 2 can be heated and kept at a constant temperature by a heater (not shown in the figure), thereby providing a good heat treatment environment for the decomposition of carburizing gas, carburizing of the workpiece, and quenching of the workpiece. The cooling chamber 1 can be vacuum exhausted and can communicate with the external environment through the front door 8. Specifically, after the front door 8 is closed, the cooling chamber 1 and the carburizing chamber 2 can be vacuum exhausted through structures and devices such as a vacuum exhaust pump and a vacuum exhaust valve, thereby increasing the vacuum degree of the cooling chamber 1 and the carburizing chamber 2 to avoid oxidation of the workpiece during carburizing.

[0019] It should be noted that the carburizing chamber 2, the cooling chamber 1, the vacuum sealing door 3, the heating chamber door 4, the carburizing trolley 5, the heater and the like are the main component structures of the existing vacuum carburizing equipment, and based on the above-mentioned vacuum carburizing equipment with the track exhaust port 7 as the only exhaust structure, in actual use, there is a problem that high-concentration carburizing gas cannot be effectively supplied at the longitudinal end of the carburizing chamber 2. Therefore, in this technical solution, a plurality of first supply ports 9 connected with carburizing gas are arranged at the middle of the longitudinal end away from the heating chamber door 4 in the carburizing chamber 2, the carburizing gas in the carburizing chamber 2 enters the first supply ports 9 and is sprayed in a radial manner, and the radial range of the carburizing gas sprayed by the first supply ports 9 can cover the longitudinal end of the carburizing chamber 2, thereby avoiding the situation that the surface carbon concentration and the carburizing depth of the workpiece placed at the longitudinal end of the carburizing chamber 2 are relatively low due to the ineffective supply of high-concentration carburizing gas. A plurality of second supply ports 10 connected with carburizing gas are arranged at the transverse sides of the carburizing chamber 2 from the longitudinal end to the heating chamber door 4, and the second supply ports 10 are arranged in a staggered manner in height to avoid the situation that the carburizing gas concentration is too high or too low at a local position in the carburizing chamber 2, thereby reducing the surface carburizing difference of the workpieces placed at different positions on the carburizing trolley 5.

[0020] Further, in this technical solution, the workpiece can be placed on the multi-layer partition or grid tray on the carburizing trolley 5, or can be hung on the carburizing trolley 5 by using a special hanger (such as a hook or a hanger).

[0021] The above, several second supply ports 10 are divided into two groups, two groups of second supply ports 10 are respectively arranged in the front half of the carburizing chamber 2 close to the heating chamber door 4 and the rear half close to the first supply port 9, and two groups of second supply ports 10 are respectively arranged on the left and right sides of the carburizing chamber 2; Each group of second supply ports 10 is arranged in two rows, and each row of second supply ports 10 is distributed linearly along the longitudinal direction of the carburizing chamber 2. Specifically, as shown in Figure 5 In the technical solution, the number of each group of second supply ports 10 is six, the same group of second supply ports 10 is divided into two rows, and the two rows of second supply ports 10 in the same group of second supply ports 10 are aligned vertically along the vertical direction perpendicular to the longitudinal direction of the carburizing chamber 2.

[0022] It should be noted that the group of second supply ports 10 located in the front half of the carburizing chamber 2 is higher than the first supply port 9, and the group of second supply ports 10 located in the rear half of the carburizing chamber 2 is lower than the first supply port 9.

[0023] The above, as shown in Figure 3 , Figure 4 The first supply port 9 extends into the carburizing chamber 2 through the gas guide pipe 11 arranged along the longitudinal direction of the carburizing chamber 2, one end of the gas guide pipe 11 arranged in the carburizing chamber 2 is closed, and the outer periphery of the one end of the gas guide pipe 11 arranged in the carburizing chamber 2 is provided with a plurality of gas guide holes 1101 along the radial direction, that is, the high-concentration carburizing gas introduced into the carburizing chamber 2 through the first supply port 9 and the gas guide pipe 11 can be sprayed radially from the gas guide holes 1101 at the end of the gas guide pipe 11, thereby covering the longitudinal end of the carburizing chamber 2.

[0024] Further, the bottom of the cooling chamber 1 is provided with an oil tank 13 for quenching, and the cooling chamber 1 is provided with a lifting platform 14 for carrying the carburizing trolley 5 and capable of vertical lifting. Specifically, the carburizing trolley 5 can be lowered into the oil tank 13 together with the lifting platform 14, the carburizing trolley 5 can be raised together with the lifting platform 14 to be connected with the conveying track 6 and / or the front door 8, and when the lifting platform 14 is raised to be connected with the conveying track 6, the carburizing trolley 5 can walk along the conveying track 6 into the carburizing chamber 2.

[0025] It should be noted that the lifting action of the lifting platform 14, the walking action of the carburizing trolley 5, and the opening and closing action of the vacuum sealing door 3, the heating chamber door 4 and the front door 8 can be realized by the existing technical equipment. Example two

[0026] Based on example one, a uniform carburizing method is realized by using the structure of the hot-wall type carburizing furnace, comprising the following steps: S1, open the front door 8, the vacuum sealing door 3, the heating chamber door 4, and send the carburizing trolley 5 with the uniformly arranged processing pieces into the cooling chamber 1, and then close the front door 8 to block the communication path between the cooling chamber 1, the carburizing chamber 2 and the external atmosphere; S2, start the vacuum exhaust of the cooling chamber 1 to exhaust the air in the cooling chamber 1 and the carburizing chamber 2 until the vacuum degree in the cooling chamber 1 and the carburizing chamber 2 reaches a predetermined value; S3, transfer the carburizing trolley 5 into the carburizing chamber 2, then close the vacuum sealing door 3 and the heating chamber door 4, and preheat the processing pieces in the carburizing chamber 2 until the temperature of the processing pieces is preheated to a preset carburizing temperature range, and the preset carburizing temperature is 800-1050℃; S4, after the preheating of the processing pieces is completed, the temperature in the carburizing chamber is maintained in the preset carburizing temperature range, and the processing pieces are carburized for a set carburizing time, during which the vacuum exhaust is periodically started and stopped, and the first supply port and the second supply port periodically introduce high-concentration carburizing gas into the carburizing chamber at a predetermined flow rate; S5, after the set carburizing time is over, the supply of high-concentration carburizing gas is cut off, and the vacuum exhaust is continuously performed, during which the temperature in the carburizing chamber is maintained in the preset carburizing temperature range for a period of time, and then is cooled to a quenching temperature and maintained for a period of time, so that all the processing pieces reach the quenching temperature; S6, after the processing pieces reach the quenching temperature, the heating chamber door and the vacuum sealing door are opened, and the processing pieces are transferred to the oil tank for quenching. After the quenching of the processing pieces is completed, the oil is drained, and the cooling chamber is pressurized to the atmospheric pressure. Finally, the front door is opened, and the processing pieces are transferred.

[0027] In the S2 step in the above, the vacuum exhaust of the cooling chamber 1 is started, that is, the vacuum exhaust pump communicated with the cooling chamber 1 and the carburizing chamber 2 is started to exhaust the air in the cooling chamber 1 and the carburizing chamber 2. When the vacuum degree in the cooling chamber 1 and the carburizing chamber 2 reaches a predetermined value, the processing pieces on the carburizing trolley 5 can also be completely in a vacuum environment. It should be noted that the number of gas molecules in the vacuum environment has been greatly reduced, and the molecular density in the cooling chamber 1 and the carburizing chamber 2 is also much lower than that in the normal atmospheric environment, and the gas molecules in the cooling chamber 1 and the carburizing chamber 2 cannot meet the conditions for the oxidation of the surface of the processing pieces.

[0028] In the S3 step in the above, before the preheating of the processing pieces, the carburizing chamber 2 can be preheated to 750-800℃ and then standby. After the processing pieces are sent into the carburizing chamber 2 and the heating chamber door 4 and the vacuum sealing door 3 are closed, the carburizing chamber 2 can be heated to the carburizing temperature (800-1050℃) required by the processing pieces and maintained for a period of time to heat the processing pieces, that is, to ensure that the temperature of each processing piece itself can reach the requirement of the carburizing temperature.

[0029] In step S4 above, due to the fixed gas flow path of the single exhaust structure, there is a problem that the high concentration of carburizing gas is difficult to supply effectively to the lower front sides of the carburizing chamber 2 near the track exhaust port 7. Therefore, in this technical solution, by periodically opening and closing the vacuum exhaust, the fixed gas flow path can be interrupted, allowing the high concentration of carburizing gas to passively diffuse, thereby increasing the concentration of carburizing gas on the lower front sides of the track exhaust port 7 and reducing the surface carburizing differences caused by uneven carburizing concentration distribution in the processed part.

[0030] In step S6 above, after opening the heating chamber door 4 and the vacuum sealing door 3 and before transferring the processed part to the oil tank 13 for quenching, the heating chamber door 4 and the vacuum sealing door 3 are closed to prevent the oil fumes generated during the quenching of the processed part from spreading into the carburizing chamber 2.

[0031] In this embodiment, samples a, b, c, d, e, f, g, h, i, j, and k located at different positions (a, b, c, d, e, f, g, h, i, j, k) can be obtained from the carburized part. Taking sample j as an example, sample j represents the sample obtained from position j, while j1, j2, j3, etc., represent multiple samples obtained from the same position. The sample acquisition position is referenced to the carburizing cart 5, and the position of the carburizing cart 5 within the carburizing chamber 2 remains unchanged during verification and actual operation. The positions of a, b, c, d, e, f, g, h, i, j, and k on the carburizing cart 2 are as follows: Figure 6 As shown, a, b, e, and f correspond to the end of the carburizing chamber 2 closest to the heating chamber door 4, while c, d, g, and h correspond to the end of the carburizing chamber 2 closest to the first supply port 9. Through analysis... Figures 6-12 The data diagram clearly shows that by adding a first supply port 9 at the longitudinal end of the carburizing chamber 2, which can radially spray carburizing gas into the carburizing chamber 2, a second supply port 10 that can introduce carburizing gas into the carburizing chamber 2 from different heights, and periodically opening and closing the vacuum exhaust and periodically introducing high-concentration carburizing gas, the uniformity of the distribution of carburizing gas in the carburizing chamber 2 can be effectively increased, and the difference in carbon concentration and carburizing depth on the surface of the treated part can be reduced.

[0032] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A hot-wall type carburizing furnace structure, comprising a vacuum-sealed door for separating a cooling chamber and a carburizing chamber, and a heating chamber door, wherein a transport track for a carburizing material cart to move along the middle of the furnace bed of the carburizing chamber is reserved, and the transport track extends to a track exhaust port below the heating chamber door to connect the carburizing chamber and the cooling chamber, the carburizing chamber can be heated and maintained at a constant temperature by a heater, the cooling chamber can be vacuum-exhausted, and can be connected to the external environment through a front door, characterized in that: The carburizing chamber has several first supply ports connected to carburizing gas at the middle of the longitudinal end away from the heating chamber door. The carburizing gas entering the carburizing chamber through the several first supply ports is sprayed radially. The carburizing chamber has several second supply ports connected to carburizing gas on both sides from the longitudinal end to the heating chamber door, and the several second supply ports are staggered in height.

2. The hot-wall type carburizing furnace structure according to claim 1, characterized in that: The second supply ports are divided into two groups, and the two groups of second supply ports are respectively located in the front half of the carburizing chamber near the heating chamber door and the rear half near the first supply port, and the two groups of second supply ports are respectively located on the left side and the right side of the carburizing chamber. The second supply ports in each group are arranged in two parallel columns, and the second supply ports in each column are distributed in a straight line along the longitudinal direction of the carburizing chamber, and are evenly spaced. A group of second supply ports located in the front half of the carburizing chamber are all higher than the first supply port, and a group of second supply ports located in the rear half of the carburizing chamber are all lower than the first supply port.

3. The hot-wall type carburizing furnace structure according to claim 1, characterized in that: The first supply port extends into the carburizing chamber through a gas guide pipe arranged longitudinally along the carburizing chamber. One end of the gas guide pipe is closed within the carburizing chamber, and a plurality of gas guide holes are arranged radially on the outer periphery of the end of the gas guide pipe within the carburizing chamber.

4. The hot-wall type carburizing furnace structure according to claim 1, characterized in that: The bottom of the cooling chamber is provided with an oil tank for quenching, and the cooling chamber is provided with a lifting platform for supporting the carburizing material car and capable of vertical lifting. The carburizing material cart can descend with the lifting platform to be submerged in the oil tank, and the carburizing material cart can rise with the lifting platform to dock with the transport rail and / or the front door. When the lifting platform rises to dock with the transport rail, the carburizing material cart can travel along the transport rail to the carburizing chamber.

5. A uniform carburizing method, implemented using the hot-wall type carburizing furnace structure as described in any one of claims 1-4, characterized in that, Includes the following steps; S1. Open the front door, vacuum seal door, and heating chamber door, and send the carburizing material car with the processed parts evenly stacked into the cooling chamber, then close the front door. S2. Start the vacuum exhaust of the cooling chamber to exhaust the air in the cooling chamber and carburizing chamber until the vacuum level in the cooling chamber and carburizing chamber reaches the predetermined value. S3. Transfer the carburizing material car to the carburizing chamber, then close the vacuum sealing door and the heating chamber door, and preheat the workpiece in the carburizing chamber until the temperature of the workpiece is preheated to the preset carburizing temperature range. S4. After the preheating of the workpiece is completed, the temperature in the carburizing chamber is maintained within the preset carburizing temperature range. The workpiece is carburized within the set carburizing time. During this period, the vacuum exhaust is periodically opened and closed. The first supply port and the second supply port periodically introduce high-concentration carburizing gas into the carburizing chamber according to a predetermined flow rate. S5. After the set carburizing time is over, cut off the supply of high-concentration carburizing gas and continue to exhaust the vacuum. During this period, the temperature in the carburizing chamber is kept within the preset carburizing temperature range for a period of time, and then cooled down to the quenching temperature and kept for a period of time so that all processed products reach the quenching temperature. S6. After the workpiece reaches the quenching temperature, open the heating chamber door and the vacuum sealing door, and transfer the workpiece to the oil tank for quenching. After the workpiece is quenched, drain the oil and pressurize the cooling chamber to atmospheric pressure. Finally, open the front door and transfer the workpiece.

6. The hot-wall type carburizing furnace structure and uniform carburizing method according to claim 5, characterized in that: After opening the heating chamber door and the vacuum sealing door and before transferring the processed part to the oil tank for quenching, close the heating chamber door and the vacuum sealing door.

7. The hot-wall type carburizing furnace structure and uniform carburizing method according to claim 5, characterized in that: The preset carburizing temperature is 800℃~1050℃.

8. The hot-wall type carburizing furnace structure and uniform carburizing method according to claim 5, characterized in that: The quenching temperature is 800℃~870℃.

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