Modular low pressure carburizing automatic line

Abstract

The present application relates to the technical field of heat treatment equipment, and in particular to a modular low-pressure carburizing automatic line, wherein the carburizing furnace, gas quenching furnace and tempering furnace are respectively connected to the automatic feeding system; the material ports of the carburizing furnace, gas quenching furnace and tempering furnace are respectively matched with the feeding device; at least two carburizing furnaces are provided, which are arranged front and back on one side of the automatic feeding system; at least two carburizing furnaces, gas quenching furnaces and tempering furnaces are arranged in sequence according to the conveying direction of the automatic feeding system; the automatic feeding system is provided with an airtight shell at a position between the two carburizing furnaces; the automatic feeding system is also provided with an airtight shell at a position between the carburizing furnace and the gas quenching furnace, which is called an airtight channel; the carburizing furnace also includes a vacuum pumping device; the vacuum pumping pipe of the vacuum pumping device is connected to the furnace of the carburizing furnace; the carburizing furnace can be vacuumed and then heated, thereby improving the heat treatment quality of parts, and then a gas quenching furnace is used in conjunction with multiple carburizing furnaces, thereby saving equipment costs.

Description

Technical Field

[0001] The present application relates to the field of heat treatment technology, in particular to an automatic carburizing line. Background Art

[0002] Part carburizing is a heat treatment process that exposes the parts to an environment containing a certain carbon atmosphere to infiltrate carbon atoms into the surface of the parts, thereby improving the hardness and wear resistance of the part surface.

[0003] In order to cope with the large-scale, high-quality and highly reproducible characteristics of gears and shaft parts in the automotive industry, large-scale production uses automated assembly lines to transport parts and automatically load them into various furnaces for heat treatment. The main control system controls the coordinated operation of the assembly lines and various furnaces.

[0004] At present, atmosphere carburizing is mainly carried out in a carburizing gas-quenching integrated furnace. Air will remain in the furnace, and the heat treatment of parts will have disadvantages such as oxide layer and poor carburizing uniformity. In addition, gas quenching is directly carried out in the furnace after carburizing in the furnace, and the heating module is easily affected by the airflow and shortens its life. When a large number of parts need to be carburized, multiple devices need to be used. Carburizing takes a long time, while gas quenching takes a short time and the equipment cost is high. One gas quenching device can be used with multiple carburizing devices, while the use of a carburizing gas-quenching integrated furnace increases the cost of the equipment. Utility Model Content

[0005] The purpose of this section is to summarize some aspects of the embodiments of the utility model and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract of the specification and the name of the utility model of this application to avoid blurring the purpose of this section, the abstract of the specification and the name of the utility model, and such simplifications or omissions cannot be used to limit the scope of the utility model.

[0006] In view of the above problems and / or the problems existing in the prior art, the present utility model is proposed.

[0007] It includes an automatic feeding system, a carburizing furnace, a gas quenching furnace and a tempering furnace, and also includes a main control system. The automatic feeding system includes a mobile feeding device for transporting materials:

[0008] The carburizing furnace, gas quenching furnace and tempering furnace are respectively connected to the automatic feeding system;

[0009] The material ports of the carburizing furnace, the gas quenching furnace and the tempering furnace are matched with the feeding devices respectively;

[0010] At least two carburizing furnaces are provided, which are arranged front and back on one side of the automatic feeding system;

[0011] At least two of the carburizing furnaces, gas quenching furnaces and tempering furnaces are arranged in sequence according to the conveying direction of the automatic feeding system;

[0012] The automatic feeding system is provided with an airtight housing between the two carburizing furnaces;

[0013] The automatic feeding system is also provided with an airtight housing, called an airtight channel, between the carburizing furnace and the gas quenching furnace;

[0014] The carburizing furnace also includes a vacuum pumping device;

[0015] The vacuum pipe of the vacuum pumping device is connected to the furnace of the carburizing furnace.

[0016] The above design optimizes the existing carburizing production line. Firstly, at least two carburizing furnaces are arranged on one side of the automatic feeding system, so that each gas quenching furnace is provided with multiple carburizing furnaces. Each carburizing furnace is fed at intervals and is used in conjunction with a gas quenching furnace that requires a shorter gas quenching time, thereby saving equipment costs. Secondly, the automatic feeding system is provided with an airtight shell between the carburizing furnaces to prevent the high-temperature parts heated by the carburizing furnace from being oxidized by the air to form an oxide layer, thereby affecting the heat treatment quality of the parts. Finally, the carburizing furnace is provided with a vacuum pumping device to extract the air in the furnace of the carburizing furnace before carburizing the parts, thereby preventing the existence of an oxide layer during the heat treatment of the parts, improving the carburizing uniformity, and thus improving the heat treatment quality of the parts.

[0017] Preferably, each of the gas quenching furnaces is equipped with 5-9 carburizing furnaces; each gas quenching furnace is equipped with multiple carburizing furnaces, so that the parts processed by the carburizing furnace can be put into the gas quenching furnace for gas quenching in turn. The single-function furnace equipment is cheaper, and the whole system saves 4-8 gas quenching devices.

[0018] Preferably, the distance between the material ports of the adjacent carburizing furnace and gas quenching furnace in the automatic feeding system is 0.8-2.0m; the time that the hot parts are exposed to the air is shortened as much as possible to prevent the formation of an oxide layer on the parts and improve the heat treatment quality of the parts.

[0019] Preferably, the distance between the material port of each of the carburizing furnace, gas quenching furnace and tempering furnace and the automatic feeding system is 30-80 cm; the carburizing furnace, gas quenching furnace and tempering furnace are docked as close to the automatic feeding system as possible to facilitate the feeding device to feed the material into or take it out of the carburizing furnace, gas quenching furnace and tempering furnace, and to facilitate the matching use of the carburizing furnace, gas quenching furnace and tempering furnace, so that one gas quenching furnace can be used in conjunction with multiple carburizing furnaces.

[0020] Preferably, the gas quenching furnace is connected to a gas circulation system, the gas circulation system includes at least two gas pipelines, and a circulation fan driving the gas circulation in the at least two gas pipelines; at least two gas delivery ports are arranged at the upper and lower ends of the furnace side of the gas quenching furnace, and the gas delivery pipelines are respectively connected to the gas delivery ports at the inner and outer ends of the furnace of the gas quenching furnace; by setting up a gas circulation system, a water-cooled heat dissipation device is arranged in the gas circulation system, which can circulate cooled nitrogen into the furnace through the two gas pipelines while transporting the high-temperature nitrogen away and returning it to the gas circulation system for cooling, so that the heated parts can be quickly cooled by the circulating cooled nitrogen to complete the quenching of the parts.

[0021] Preferably, the gas circulation system also includes an electric reversing valve; two gas source airflow ports are provided on the gas source side of the electric reversing valve; two gas supply airflow ports are provided on the gas supply side of the electric reversing valve; the two gas source airflow ports of the electric reversing valve are respectively connected to the air inlet and the air outlet of the circulating fan; the two gas pipelines are respectively connected to the two gas supply airflow ports of the electric reversing valve, so that the air inlet and the air outlet of the circulating fan are respectively connected to the two gas pipelines; by setting the electric reversing valve, the flow direction of the circulating nitrogen in the furnace is reversed once every 6-12 seconds (from top to bottom to bottom to top, or from bottom to top to top to bottom), so that the direction of the airflow in the furnace can be switched periodically, thereby improving the uniformity of the temperature in the furnace, ensuring uniform cooling of slender parts, reducing deformation, and improving the quality of part quenching.

[0022] Preferably, a limiter is also provided on the automatic feeding system, and the limiter is provided on the slide rail of the automatic feeding system; each of the carburizing furnace, gas quenching furnace and tempering furnace is provided with a limiter at a corresponding position on one side of the automatic feeding system; the signal output end of the main control system is controlled to be connected to the limiter; it also includes an infrared counter-radiation sensor, and the infrared emitting element and the infrared receiving element of the infrared counter-radiation sensor are respectively located on both sides of the slide rail at the loading point, forming a counter-radiation arrangement structure; the signal output end of the infrared counter-radiation sensor is connected to the signal input end of the main control system; the position of the loading device is determined by setting a limiter using the infrared counter-radiation sensor, and then the loading device is limited to the vicinity of the material ports of the carburizing furnace, gas quenching furnace and tempering furnace respectively through the limiter, so as to achieve the goal of transferring parts between furnaces through a mobile loading device for transporting materials, so that one gas quenching furnace can be used in conjunction with multiple carburizing furnaces.

[0023] Preferably, it also includes a cleaning device and a preheating furnace, and the cleaning device and the preheating furnace are both arranged on one side of the automatic feeding system; by arranging the cleaning device and the preheating furnace, the parts can be first cleaned to remove surface impurities, and then the moisture can be removed by the preheating furnace, thereby improving the subsequent heat treatment quality of the parts.

[0024] Preferably, the structure of the feeding device contacting the parts is made of nickel-based alloy material; the nickel-based alloy material structure can withstand the high temperature of the parts treated in the carburizing furnace, and facilitates the matching use of one gas quenching furnace with multiple carburizing furnaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following briefly introduces the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0026] Figure 1 A schematic diagram of the overall structure of a modular low-pressure carburizing automatic line according to an embodiment of the utility model;

[0027] Figure 2 A schematic diagram of the gas circulation system connection structure of a quenching furnace in a modular low-pressure carburizing automatic line according to an embodiment of the utility model;

[0028] Figure 3 A schematic diagram of the structural principle of an electric reversing valve for changing the direction of airflow in a modular low-pressure carburizing automatic line according to an embodiment of the utility model. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned purposes, features and advantages of the present invention more understandable, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0031] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general proportion, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0032] Secondly, the "one embodiment" or "embodiment" referred to herein refers to a specific feature, structure or characteristic that can be included in at least one implementation of the utility model. The "in one embodiment" that appears in different places in this specification does not refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0033] Example 1

[0034] Reference Figure 1 and Figure 2 This embodiment provides a modular low-pressure carburizing automatic line, including an automatic feeding system 1, a carburizing furnace 2, a gas quenching furnace 3 and a tempering furnace 4, and also includes a main control system. The automatic feeding system 1 includes a mobile feeding device 5 for transporting materials.

[0035] The carburizing furnace 2, gas quenching furnace 3 and tempering furnace 4 are respectively connected to the automatic feeding system 1; the material ports of the carburizing furnace 2, gas quenching furnace 3 and tempering furnace 4 are matched with the feeding device 5 respectively; at least two carburizing furnaces 2 are provided, which are arranged front and back on one side of the automatic feeding system 1; according to the conveying direction of the automatic feeding system 1, at least two carburizing furnaces 2, gas quenching furnaces 3 and tempering furnaces 4 are arranged in sequence; the automatic feeding system 1 is provided with an airtight shell at a position between the two carburizing furnaces 2; the automatic feeding system 1 is also provided with an airtight shell at a position between the carburizing furnace 2 and the gas quenching furnace 3, which is called an airtight channel; the carburizing furnace 2 also includes a vacuum pumping device; the vacuum pumping pipe of the vacuum pumping device is connected to the furnace of the carburizing furnace 2; through the automatic At least two carburizing furnaces 2 are arranged on one side of the feeding system 1, so that each gas quenching furnace 3 is correspondingly provided with multiple carburizing furnaces 2. Each carburizing furnace 2 is fed at intervals and is used in conjunction with the gas quenching furnace 3 which requires a shorter gas quenching time, thereby saving equipment costs; secondly, the automatic feeding system 1 is provided with an airtight shell between the carburizing furnaces 2 to prevent the high-temperature parts heated by the carburizing furnace 2 from being oxidized by the air to form an oxide layer, thereby affecting the heat treatment quality of the parts; finally, the carburizing furnace 2 is provided with a vacuum pumping device to extract the air in the furnace of the carburizing furnace 2 before carburizing the parts, thereby preventing the existence of an oxide layer during the heat treatment of the parts, improving the carburizing uniformity, and thus improving the heat treatment quality of the parts. The microprocessor system model of the main control system is S7-1500, which is a common technology used by people in this field for carburizing automatic lines.

[0036] The airtight shell and the airtight passage are both configured to allow the feeding device 5 to pass through.

[0037] The airtight housing and airtight passage are not limited to structures that completely isolate the air, but are limited to structures that restrict the flow of gas.

[0038] The airtight shell and the airtight passage are connected with a booster fan, and the air inlet of the booster fan is connected to an air source to provide clean pressurized gas for the airtight shell and the airtight passage, thereby further preventing air intrusion.

[0039] The heating body of the carburizing furnace 2 is a heating source made of graphite, which can achieve thermal radiation heating of the parts, so that the parts can still be evenly heated in the furnace of the vacuum carburizing furnace 2 after being evacuated, thereby improving the carburizing quality.

[0040] Each of the gas quenching furnaces 3 is equipped with 5-9 carburizing furnaces 2; each gas quenching furnace 3 is equipped with multiple carburizing furnaces 2, so that the parts processed by the carburizing furnace 2 can be put into the gas quenching furnace 3 for gas quenching in turn. The single-function furnace equipment is cheaper, and the whole system saves 4-8 gas quenching devices, saving equipment costs.

[0041] Each gas quenching furnace 3 is equipped with two tempering furnaces 4, so that after the parts heat-treated in multiple carburizing furnaces 2 are gas quenched, there are enough tempering furnaces 4 to process multiple groups of parts, so that one gas quenching furnace 3 can be used in conjunction with multiple carburizing furnaces 2, saving equipment costs.

[0042] The distance between the material ports of the automatic feeding system 1 and the adjacent carburizing furnace 2 and gas quenching furnace 3 is 0.8-2.0m; the time that the hot parts are exposed to the air is shortened as much as possible to prevent the formation of an oxide layer on the parts and improve the heat treatment quality of the parts.

[0043] The distance between the material ports of the carburizing furnace 2, gas quenching furnace 3 and tempering furnace 4 and the automatic feeding system 1 is 30-80 cm; the carburizing furnace 2, gas quenching furnace 3 and tempering furnace 4 are connected as close to the automatic feeding system 1 as possible, so that the loading device 5 can conveniently feed the materials into or take them out of the carburizing furnace 2, gas quenching furnace 3 and tempering furnace 4, and facilitate the matching use of the carburizing furnace 2, gas quenching furnace 3 and tempering furnace 4, so that one gas quenching furnace 3 can be used in conjunction with multiple carburizing furnaces 2.

[0044] The automatic feeding system 1 is also provided with a limiter, and the limiter is arranged on the slide rail of the automatic feeding system 1; each of the carburizing furnace 2, gas quenching furnace 3 and tempering furnace 4 is provided with a limiter at the corresponding position on one side of the automatic feeding system 1; the signal output end of the main control system is controlled to be connected to the limiter; it also includes an infrared counter-radiation sensor, and the infrared emitting element and the infrared receiving element of the infrared counter-radiation sensor are respectively located on both sides of the slide rail at the loading point, forming a counter-radiation arrangement structure; the signal output end of the infrared counter-radiation sensor is connected to the signal input end of the main control system; by setting a limiter, the position of the feeding device 5 is determined by using the infrared counter-radiation sensor, and then the feeding device 5 is limited by the limiter to the vicinity of the material ports of the carburizing furnace 2, the gas quenching furnace 3 and the tempering furnace 4 respectively, so that the parts can be transferred between the furnaces by the mobile feeding device 5 for transporting materials, so that one gas quenching furnace 3 can be used in conjunction with multiple carburizing furnaces 2.

[0045] It also includes a cleaning device 6 and a preheating furnace 7, which are both arranged on one side of the automatic feeding system 1; by arranging the cleaning device 6 and the preheating furnace 7, the parts can be cleaned first to remove surface impurities, and then the preheating furnace 7 can be used to remove moisture, thereby improving the subsequent heat treatment quality of the parts.

[0046] The structure of the feeding device 5 contacting the parts is made of nickel-based alloy material; the nickel-based alloy material structure can withstand the high temperature of the parts treated by the carburizing furnace 2, and is convenient for the matching use of one gas quenching furnace 3 with multiple carburizing furnaces 2.

[0047] When in use, the parts to be processed are first transported to the cleaning device 6 for cleaning through the feeding device 5. After cleaning, the feeding device 5 takes out the parts in the cleaning device 6, and then puts the parts into the preheating furnace 7 for preheating to remove moisture. Then the feeding device 5 puts the preheated parts into a carburizing furnace 2, and repeats the above operation to put parts into all the carburizing furnaces 2. The carburizing treatment of the parts in the first carburizing furnace 2 is completed, the feeding device 5 takes the parts out of the carburizing furnace 2, and then puts them into the gas quenching furnace 3 for quenching, and then puts the quenched parts from the gas quenching furnace 3 into the tempering furnace 4 for tempering. The tempered parts are taken out and the heat treatment is completed, and the parts are continued to be cleaned and then put into the carburizing furnace 2 for carburization, and then the parts processed by the second carburizing furnace 2 are put into the quenching furnace for treatment, and the heat treatment of the second batch of parts is completed after tempering. In this way, the other 6-8 carburizing furnaces 2 are used in conjunction with one quenching furnace, which reduces the equipment cost of heat treatment of large quantities of parts, and the carburizing quality of the parts is guaranteed by the vacuum pumping device and the airtight channel in the carburizing furnace 2.

[0048] Example 2

[0049] Reference Figure 2 and Figure 3, which is the second embodiment of the utility model, and this embodiment is based on the previous embodiment.

[0050] The gas quenching furnace 3 is connected to a gas circulation system, which includes at least two gas pipelines 8 and a circulation fan that drives the gas circulation in the at least two gas pipelines 8; at least two gas delivery ports are arranged at the upper and lower ends of the furnace side of the gas quenching furnace 3, and the gas pipeline 8 is respectively connected to the gas delivery ports at the inner and outer ends of the furnace of the gas quenching furnace 3; by setting up a gas circulation system, a water-cooled heat dissipation device is arranged in the gas circulation system, which can circulate cooled nitrogen into the furnace through the gas pipeline 8 while transporting the high-temperature nitrogen away and returning it to the gas circulation system for cooling, so that the heated parts can be quickly cooled by the circulating cooled nitrogen to complete the quenching of the parts.

[0051] The gas circulation system also includes an electric reversing valve 9; two gas source airflow ports 10 are provided on the gas source side of the electric reversing valve 9; two gas supply airflow ports 10 are provided on the gas supply side of the electric reversing valve 9; the two gas source airflow ports 10 of the electric reversing valve 9 are respectively connected to the air inlet and the air outlet of the circulating fan; the two gas pipelines 8 are respectively connected to the two gas supply airflow ports 10 of the electric reversing valve 9, so that the air inlet and the air outlet of the circulating fan are respectively connected to the two gas pipelines 8; by setting the electric reversing valve 9, the flow direction of the circulating nitrogen in the furnace is reversed once every 6-12 seconds (from top to bottom to bottom to top, or from bottom to top to top to bottom), so that the direction of the airflow in the furnace can be switched periodically, thereby improving the uniformity of the temperature in the furnace, ensuring uniform cooling of slender parts, reducing deformation, and improving the quality of part quenching.

[0052] When in use, the gas quenching furnace 3 circulates nitrogen through the circulating fan through the gas circulation system, quickly raising the nitrogen in the furnace to a rated gas quenching pressure of more than bar, and inputs the nitrogen into the furnace of the gas quenching furnace 3 from a gas delivery port of the gas quenching furnace 3 through the gas delivery pipeline 8, and then the nitrogen in the furnace of the gas quenching furnace 3 is extracted through the gas delivery pipeline 8 from another gas delivery port, thereby realizing the circulating flow of nitrogen, and then through the electric reversing valve 9 (the nitrogen flow direction is switched in about 10 seconds), the rapid and uniform gas quenching of the parts is ensured, thereby improving the heat treatment quality of the parts.

[0053] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and ratio of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangements, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present utility model. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and is not only structurally equivalent but also an equivalent structure. Without departing from the scope of the present invention, other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the present invention is not limited to a specific embodiment, but extends to various modifications that still fall within the scope of the appended claims.

[0054] Additionally, in order to provide a concise description of example embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0055] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0056] It should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A modular low-pressure carburizing automatic line, comprising an automatic feeding system, a carburizing furnace, a gas quenching furnace and a tempering furnace, and also comprising a main control system. The automatic feeding system comprises a mobile feeding device for transporting materials, characterized in that: The carburizing furnace, gas quenching furnace and tempering furnace are respectively connected to the automatic feeding system; The material ports of the carburizing furnace, the gas quenching furnace and the tempering furnace are matched with the feeding devices respectively; At least two carburizing furnaces are provided, which are arranged front and back on one side of the automatic feeding system; At least two of the carburizing furnaces, gas quenching furnaces and tempering furnaces are arranged in sequence according to the conveying direction of the automatic feeding system; The automatic feeding system is provided with an airtight housing between the two carburizing furnaces; The automatic feeding system is also provided with an airtight housing, called an airtight channel, between the carburizing furnace and the gas quenching furnace; The carburizing furnace also includes a vacuum pumping device; The vacuum pipe of the vacuum pumping device is connected to the furnace of the carburizing furnace.

2. The modular low-pressure carburizing automatic line according to claim 1 is characterized in that: Each of the gas quenching furnaces is equipped with 5 to 9 carburizing furnaces.

3. The modular low-pressure carburizing automatic line according to claim 2 is characterized in that: Automatic feeding system: the distance between the adjacent material ports of the carburizing furnace and the gas quenching furnace is 0.8-2.0m.

4. The modular low-pressure carburizing automatic line according to claim 3 is characterized in that: The distance between the material ports of the carburizing furnace, the gas quenching furnace and the tempering furnace and the automatic feeding system is 30-80 cm.

5. The modular low-pressure carburizing automatic line according to claim 4 is characterized in that: The gas quenching furnace is connected to a gas circulation system, which includes at least two gas pipelines and a circulation fan for driving gas circulation in the at least two gas pipelines; At least two gas delivery ports are arranged at the upper and lower ends of the furnace side of the gas quenching furnace, and the gas delivery pipeline is respectively connected to the gas delivery ports at the inner and outer ends of the furnace of the gas quenching furnace.

6. The modular low-pressure carburizing automatic line according to claim 5 is characterized in that: The gas circulation system also includes an electric reversing valve; Two air source flow ports are provided on the air source side of the electric reversing valve; Two air supply ports are provided on the air supply side of the electric reversing valve; The two air source air flow ports of the electric reversing valve are respectively connected to the air inlet and the air outlet of the circulating fan; The two gas pipelines are respectively connected to the two gas supply ports of the electric reversing valve, so that the air inlet and the air outlet of the circulating fan are respectively connected to the two gas pipelines.

7. The modular low-pressure carburizing automatic line according to claim 6 is characterized in that: The automatic feeding system is also provided with a limiter, and the limiter is arranged on the slide rail of the automatic feeding system; Each of the carburizing furnace, gas quenching furnace and tempering furnace is provided with a limiter at a corresponding position on one side of the automatic feeding system; The signal output terminal of the main control system is controlled to be connected to the limiter; It also includes an infrared counter-radiation sensor, wherein the infrared emitting element and the infrared receiving element of the infrared counter-radiation sensor are respectively located on both sides of the slide rail at the loading point, forming a counter-radiation arrangement structure; The signal output end of the infrared radiation sensor is connected to the signal input end of the main control system.

8. The modular low-pressure carburizing automatic line according to claim 7 is characterized in that: It also includes a cleaning device and a preheating furnace, and the cleaning device and the preheating furnace are both arranged on one side of the automatic feeding system.

9. The modular low-pressure carburizing automatic line according to claim 1, characterized in that: The structure of the contact parts of the feeding device is made of nickel-based alloy material.

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