阅读说明：本技术 复合渗碳工艺与设备 (Composite carburizing process and equipment ) 是由 朱小军 胜俣和彦 苏阳 于 2021-10-11 设计创作，主要内容包括：本发明的实施例提供了一种复合渗碳工艺与设备,涉及热处理技术领域,该复合渗碳设备包括渗碳炉体、加热室、第一抽真空装置、碳势控制装置和渗碳气体通入装置,渗碳炉体具有加热区与冷却区,加热室设置在加热区,第一抽真空装置与加热室连接,渗碳气体通入装置与加热室连接,碳势控制装置设置在加热室内,用于在缓冷阶段对加热室内的碳势进行控制,以使得产品表面的碳浓度均匀分布。相较于现有技术,本发明额外设置有碳势控制装置,从而能够控制加热室内的碳势,从而能够在真空渗碳的最后阶段进行CP控制,可使表面碳浓度不均匀被大幅缓和,从而避免了产生残留的奥氏体,进而大幅提升了产品的质量。(The embodiment of the invention provides a composite carburizing process and equipment, relating to the technical field of heat treatment. Compared with the prior art, the carbon potential control device is additionally arranged, so that the carbon potential in the heating chamber can be controlled, CP control can be performed at the final stage of vacuum carburization, the uneven surface carbon concentration can be greatly alleviated, the generation of residual austenite is avoided, and the product quality is greatly improved.)

1. The utility model provides a compound carburization equipment, its characterized in that includes carburization furnace body, heating chamber, first evacuating device, carbon potential controlling means and carburizing gas lets in the device, the carburization furnace body has the zone of heating and cooling zone, the heating chamber sets up the zone of heating for heat the product, first evacuating device with the heating chamber is connected, is used for to carry out evacuation processing to the heating chamber, carburizing gas lets in the device with the heating chamber is connected, is used for to letting in carburizing gas in the heating chamber under the vacuum state, in order to carry out vacuum carburization to the product, carbon potential controlling means sets up in the heating chamber, be used for to control the carbon potential in the heating chamber, so that the carbon concentration evenly distributed on product surface.

2. The hybrid carburizing equipment according to claim 1, wherein the cooling zone is provided with an internal conveying device, a feed opening is arranged on the end surface of the furnace body far away from the heating zone, a front door is arranged on the feed opening, and the internal conveying device is used for conveying the product from the feed opening to the heating chamber.

3. The hybrid carburizing apparatus according to claim 2, wherein a cooling tank is further provided below the internal conveyance device, and cooling oil is provided in the cooling tank for oil-cooling the product.

4. The hybrid carburizing apparatus according to claim 2, wherein an air cooling device is further provided above the internal conveyance device, and the air cooling device is configured to air-cool the product.

5. The hybrid carburizing apparatus according to claim 1, wherein an end of the heating chamber remote from the cooling zone is further provided with a convection fan located at least partially within the heating chamber for agitating the gas within the heating chamber.

6. The composite carburizing equipment according to claim 1, further comprising a second vacuumizing device, wherein a furnace body vacuum exhaust port is arranged on the carburizing furnace body, and the second vacuumizing device is connected with the furnace body vacuum exhaust port and is used for vacuumizing the carburizing furnace body.

7. The hybrid carburizing apparatus according to claim 1, wherein an end of the heating chamber near the cooling zone is provided with a heating door for closing after the product enters the heating chamber.

8. The composite carburizing apparatus according to claim 1, characterized in that the carbon potential control device includes a carbon potential meter and a carbon potential control valve, the carbon potential meter is provided in the heating chamber and measures the carbon potential in the heating chamber, the carbon potential control valve is connected to the carbon potential meter, a carburizing gas introduction port is provided in the heating chamber, the carburizing gas introduction device is connected to the carburizing gas introduction port, and the carbon potential control valve is provided in the carburizing gas introduction port and controls the flow rate of the carburizing gas entering the heating chamber.

9. A composite carburization process adapted for use in a composite carburization apparatus according to any one of claims 1 to 8, characterized in that the process comprises:

loading the product into a heating chamber under vacuum;

heating a heating chamber in a vacuum state to heat the product;

soaking the heating chamber;

introducing carburizing gas into the heating chamber through a carburizing gas introduction device so as to carburize the product;

slowly cooling the heating chamber, and controlling the carbon potential in the heating chamber by using a carbon potential control device so as to ensure that the carbon concentration on the surface of the product is uniformly distributed;

cooling the product.

10. The composite carburization process of claim 9 further comprising, prior to the step of loading the product into a heated chamber under vacuum:

and carrying out vacuum pumping treatment on the carburizing furnace body.

Technical Field

The invention relates to the technical field of heat treatment, in particular to a composite carburizing process and equipment.

Background

In the field of heat treatment, there are two main types of current carburizing methods: the atmosphere carburizing and the vacuum carburizing are adopted, the grain boundary oxide layer is easy to generate on the surface of a treated product by adopting the atmosphere carburizing, the quality of the product is not facilitated, in addition, in order to avoid carbon deposition, a quite long time is required before the target CP is formed, and the improvement of the heat treatment efficiency of the product is not facilitated. Further, a vacuum carburization method has appeared, but the vacuum carburization is a carburization method with a low degree of control. This is because it depends on the shape of the product, and therefore, a phenomenon of non-uniform carbon concentration occurs on the surface of the product. In particular, in the case of a processed product having an acute angle portion, the carbon concentration near the tip is high, and therefore retained austenite may be generated, which may affect the quality of the product.

Disclosure of Invention

Objects of the invention include, for example, providing a composite carburization process and apparatus that improves product quality.

Embodiments of the invention may be implemented as follows:

in a first aspect, the invention provides composite carburizing equipment, which comprises a carburizing furnace body, a heating chamber, a first vacuumizing device, a carbon potential control device and a carburizing gas introducing device, wherein the carburizing furnace body is provided with a heating region and a cooling region, the heating chamber is arranged in the heating region and is used for heating the product, the first vacuumizing device is connected with the heating chamber and is used for vacuumizing the heating chamber, the carburizing gas introducing device is connected with the heating chamber and is used for introducing carburizing gas into the heating chamber in a vacuum state so as to realize vacuum carburizing of the product, and the carbon potential control device is arranged in the heating chamber and is used for controlling the carbon potential in the heating chamber in a slow cooling stage so that the carbon concentration on the surface of the product is uniformly distributed.

In an optional embodiment, the cooling zone is provided with an internal conveying device, a feed inlet is arranged on an end surface of the furnace body far away from the heating zone, a front door is arranged on the feed inlet, and the internal conveying device is used for conveying the product from the feed inlet to the heating chamber.

In an optional embodiment, a cooling tank is further disposed below the internal conveying device, and cooling oil is disposed in the cooling tank and used for performing oil cooling on the product.

In an optional embodiment, an air cooling device is further disposed above the internal conveying device, and the air cooling device is used for air cooling the product.

In an alternative embodiment, a convection fan is further disposed at an end of the heating chamber remote from the cooling region, the convection fan extending into the heating chamber for agitating the gas within the heating chamber.

In an optional embodiment, the composite carburizing equipment further comprises a second vacuumizing device, wherein a furnace body vacuum exhaust port is arranged on the carburizing furnace body, and the second vacuumizing device is connected with the furnace body vacuum exhaust port and is used for vacuumizing the carburizing furnace body.

In an alternative embodiment, the heating chamber is provided with a heating door at an end thereof adjacent the cooling zone, the heating door being adapted to close after the product has entered the heating chamber.

In an alternative embodiment, the carbon potential control device includes a carbon potential meter and a carbon potential control valve, the carbon potential meter is disposed in the heating chamber and is used for measuring the carbon potential in the heating chamber, the carbon potential control valve is connected to the carbon potential meter, a carburizing gas inlet is disposed on the heating chamber, the carburizing gas introducing device is connected to the carburizing gas inlet, and the carbon potential control valve is disposed on the carburizing gas inlet and is used for controlling the flow rate of the carburizing gas entering the heating chamber.

In a second aspect, the present invention provides a composite carburization process adapted for use in a composite carburization apparatus according to any one of the preceding embodiments, the process comprising:

loading the product into a heating chamber under vacuum;

heating a heating chamber in a vacuum state to heat the product;

soaking the heating chamber;

introducing carburizing gas into the heating chamber through a carburizing gas introduction device so as to carburize the product;

slowly cooling the heating chamber, and controlling the carbon potential in the heating chamber by using a carbon potential control device so as to ensure that the carbon concentration on the surface of the product is uniformly distributed;

cooling the product.

In an alternative embodiment, prior to the step of loading the product into the heating chamber under vacuum, the process further comprises:

and carrying out vacuum-pumping treatment on the furnace body.

The beneficial effects of the embodiment of the invention include, for example:

the composite carburizing process and the composite carburizing equipment provided by the embodiment of the invention have the advantages that the heating zone and the cooling zone are arranged in the carburizing furnace body, the heating chamber is arranged in the heating zone, the first vacuumizing device is connected with the heating chamber and is used for vacuumizing the heating chamber, the carburizing gas introducing device is connected with the heating chamber, and the carburizing gas is introduced into the heating chamber in a vacuum state, so that the vacuum carburizing of the product is realized. In addition, the invention is additionally provided with a carbon potential control device which is arranged in the heating chamber and used for controlling the carbon potential in the heating chamber so as to ensure that the carbon concentration is uniformly distributed on the surface of the product. Compared with the prior art, the carbon potential control device is additionally arranged, so that the carbon potential in the heating chamber can be controlled, CP control can be performed at the final stage of vacuum carburization, the uneven surface carbon concentration can be greatly alleviated, the generation of residual austenite is avoided, and the product quality is greatly improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a schematic diagram of the overall structure of a composite carburizing apparatus according to an embodiment of the invention;

FIG. 2 is a schematic view showing a connection structure of the heating chamber of FIG. 1;

FIG. 3 is a schematic structural view of the heating zone of FIG. 1;

FIG. 4 is a block diagram illustrating steps in a composite carburization process according to an embodiment of the present invention.

Icon: 100-composite carburizing equipment; 110-carburizing furnace body; 111-a heating zone; 113-a cooling zone; 115-internal conveyance device; 117-front door; 119-furnace body vacuum exhaust port; 120-a heating chamber; 121-convection fan; 123-a heating door; 130-a first vacuum; 140-a carbon potential control device; 141-carbon potential measuring instrument; 143-carbon potential control valve; 160-carburizing gas introduction means; 161-carburizing gas introduction port; 170-cooling tank; 180-air cooling device; 190-a second vacuum extractor.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. indicate an orientation or a positional relationship based on that shown in the drawings or that the product of the present invention is used as it is, this is only for convenience of description and simplification of the description, and it does not indicate or imply that the device or the element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention.

Furthermore, the appearances of the terms "first," "second," and the like, if any, are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

As disclosed in the background art, the prior art carburizing processes all have significant problems. For example, atmospheric carburizing in conventional processes generally uses carbon monoxide (CO) as the main carburizing gas. In the case of endothermic gasification, carbon monoxide is adjusted to 20 to 24.5% to generate a base gas. However, since the carbon (hereinafter, referred to as CP) in the base gas is low, a gas called a richened gas (hydrocarbon gas such as propane) is added, and the carbon monoxide concentration and the hydrogen concentration required for the carburizing reaction are increased. Air is typically used to lower the CP. These reactions are maintained in equilibrium by various reactions of the gases residing in the furnace. Since the treatment products are also carburized subtly in the temperature rise, soaking, and slow cooling regions, carburization variation occurs between the treatment products according to the temperature rise, soaking, and slow cooling processes. Further, since oxygen components are involved in the whole heat treatment process, a grain boundary oxide layer is formed on the surface of the treated product, which is not favorable for the quality of the product. In addition, CP control as a characteristic is generally controlled in a wide range of 0.6 to 1.2. From warm-up, soaking time (low CP) to carburization: 0.8-1.2, the transfer of the liquid is preceded by the introduction of a rich gas (hydrocarbon, mainly propane). If it is rapidly input, carbon deposition is generated, so that a minute amount of input is required, so that a considerable time is required before the formation of the target CP, which is disadvantageous in improving the heat treatment efficiency of the product. Further, from the carburizing step to the atmosphere adjustment (diffusion step): 0.6-0.7, air is generally required to be added for reducing CP, and the larger the difference of transition CP is, the more easily a grain boundary oxide layer is generated on the surface of a treated product, thereby further reducing the product quality. Further, since the environments surrounding the facilities vary from day to day due to the impure components in the atmosphere management, such as moisture in the air, dew point management is required in the atmosphere management. Since the carburizing gas used is carbon monoxide, it is necessary to perform safety management such as exhaust gas treatment and gas leakage.

Further, the conventional vacuum carburization method has a problem that the surface carbon amount increases in the course of reaching the carbon solid solution limit point (a3-Acm point) of the carburization temperature at the time of carburization. This is a method of reducing the carbon concentration to the target surface by diffusion after. Meanwhile, vacuum carburization causes diffusion hindrance depending on the shape. For example, the diffusion inside the acute angle part is concentrated, and the tip of the acute angle part is not sufficiently diffused, thereby generating a portion having a high carbon concentration. That is, although the shape is dependent, the amount of carbon on the surface varies in one part, resulting in a phenomenon in which the carbon concentration is not uniform on the surface of the final product, and thus residual austenite may be generated, thereby affecting the quality of the product. In order to minimize the influence of the carbon concentration, the divided carburizing and the pulse carburizing have been conventionally performed, but this requires that the carburizing conditions be determined according to the shape of each member, and is not applicable, and it is not possible to perform the mixed loading treatment of different shapes.

In order to solve the above problems, the present invention provides a novel carburization-compliant apparatus and method, and it should be noted that the features of the embodiments of the present invention may be combined with each other without conflict.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

Referring to fig. 1 to 3 in combination, the present embodiment provides a hybrid carburizing apparatus 100, which can perform CP control in the final stage of vacuum carburizing, and greatly alleviate the uneven surface carbon concentration, thereby avoiding the generation of retained austenite, and further greatly improving the quality of the product.

The composite carburizing equipment 100 provided by the embodiment comprises a carburizing furnace body 110, a heating chamber 120, a first vacuumizing device 130, a carbon potential control device 140 and a carburizing gas introducing device 160, wherein the carburizing furnace body 110 is provided with a heating region 111 and a cooling region 113, the heating chamber 120 is arranged in the heating region 111 and is used for heating a product, the first vacuumizing device 130 is connected with the heating chamber 120 and is used for vacuumizing the heating chamber 120, the carburizing gas introducing device 160 is connected with the heating chamber 120 and is used for introducing carburizing gas into the heating chamber 120 in a vacuum state so as to realize vacuum carburizing of the product, and the carbon potential control device 140 is arranged in the heating chamber 120 and is used for controlling the carbon potential in the heating chamber 120 in a slow cooling stage so as to enable the carbon concentration on the surface of the product to be uniformly distributed.

In this embodiment, the entire carburizing furnace body 110 is a vacuum-proof sealed pressure vessel, so that the outside can be isolated and the sealing property can be ensured when the inside is subjected to heat treatment. It should be noted that, the vacuum concepts mentioned in the embodiments refer to vacuum concepts known in the field of thermal processing, that is, the gas content and pressure inside the vacuum concepts meet certain standards, and reference may be made to the related descriptions in the prior art.

In this embodiment, the cooling zone 113 is provided with an internal conveying device 115, the furnace body is provided with a feed inlet on the end surface far away from the heating zone 111, a front door 117 is arranged on the feed inlet, and the internal conveying device 115 is used for conveying products from the feed inlet to the heating chamber 120. Specifically, the internal conveyance device 115 may be a chain conveyor or a slide conveyor, and the specific form thereof is not limited herein. In actual conveyance, the front door 117 may be opened, the product may be placed on the internal conveyance device 115, and the product may be conveyed backward by a slide rail or a chain until the product is conveyed into the heating chamber 120.

In this embodiment, a cooling tank 170 is further provided below the internal conveyance device 115, and cooling oil is provided in the cooling tank 170 to cool the product. Specifically, the cooling tank 170 is disposed below the cooling zone 113, and the inside thereof is filled with cooling oil for quenching the product. Here, in order to further ensure the uniformity of oil cooling, a stirring device is further provided in the cooling tank 170, and the cooling oil can be stirred by the stirring device, so that the heat distribution is more uniform. Specifically, the stirring may be performed by an oil stirrer, wherein the rotation speed of the oil stirrer may be selected to determine the uniformity of oil cooling, and the stirring speed may be changed by changing the rotation speed of the motor using a motor as a rotation power source by an inverter or the like. Wherein a high rotational speed increases the fluidity of the oil, with the result that the cooling rate increases. However, the difference between a place where the cooling is easily conducted and a place where the cooling is not easily conducted by the high-speed stirring is expanded, and as a result, the hardness may be deviated. The low rotation is the opposite, and the difference between the cold place and the place which is not easy to be cooled is reduced, so that the uniformity of cooling is more favorable, and the specific rotating speed of the oil mixer is not limited and can be set according to the actual requirement.

In this embodiment, an air cooling device 180 is further disposed above the internal conveyance device 115, and the air cooling device 180 is used for air cooling the product. Specifically, when quenching is performed in the cooling bath 170, a large amount of oil smoke is generated, and the oil smoke is cooled by the air-cooling device 180, thereby indirectly air-cooling the product. Here, the air cooling device 180 may include an air cooling blade and a heat exchanger, wherein the air cooling blade sucks up the oil smoke or air with a large amount of heat, and exchanges heat between the air or oil smoke and the heat exchanger, thereby achieving a cooling effect. Of course, in view of the air cooling effect, the air cooling device 180 may be directly conducted to the external space to rapidly discharge heat to the external space, and a good cooling effect can be achieved.

In the actual oil cooling, the pressure is selected from the furnace pressures (for example, 70kPa, 50kPa, 30kPa, and 10 kPa). Note that the pressure is highest when oil cooling is performed, and here, the pressure in the carburizing furnace body 110 is not set to a pressure close to atmospheric pressure, because soot is generated when a heated product is put into cooling oil, and the furnace internal pressure is instantaneously increased. If the pressure is below 1 atmosphere, the oil smoke will not be discharged out of the furnace. As a countermeasure against the oil smoke, the air-cooling device 180 may be activated, and the flying oil smoke is cooled to reduce the raised internal furnace pressure.

In this embodiment, the end of the heating chamber 120 remote from the cooling zone 113 is further provided with a convection fan 121, and the convection fan 121 extends into the heating chamber 120 for agitating the gas in the heating chamber 120. Specifically, the convection dispersion is provided in the heating chamber 120, and the gas in the heating chamber 120 can be agitated, so that the heating uniformity can be improved by ensuring that the heating is uniform everywhere in the heating chamber 120.

Further, in this embodiment, the composite carburizing apparatus 100 further includes a second vacuum extractor 190, the carburizing furnace body 110 is provided with a furnace body vacuum exhaust port 119, and the second vacuum extractor 190 is connected to the furnace body vacuum exhaust port 119 and is used for performing vacuum extraction on the carburizing furnace body 110. Specifically, the second vacuum extractor 190 is directly connected to the carburizing furnace body 110 as a whole, so that the carburizing furnace body 110 can be subjected to the entire vacuum extraction process.

Here, the heating chamber 120 is also provided with a vacuum line connected to the first vacuum extractor 130, and the heating chamber 120 can be subjected to vacuum processing by the first vacuum extractor 130. Alternatively, the first vacuum extractor 130 and the second vacuum extractor 190 may be integrated, that is, the vacuum extractor may be used to perform the vacuum process on the heating chamber 120 and the carburizing furnace body 110. Of course, the first vacuum pumping device 130 and the second vacuum pumping device 190 may be pumped by vacuum pumps, and the specific operation principle may refer to the existing vacuum pumping equipment.

In this embodiment, a heating door 123 is provided at an end of the heating chamber 120 near the cooling zone 113, and the heating door 123 is used for closing after the product enters the heating chamber 120. The heating door 123 is used to realize heat insulation so that heat does not largely escape to the cooling area 113 while the heating chamber 120 is being operated in the heating chamber 120. Here, an isolation door for isolating the atmosphere may be further provided between the heating chamber 120 and the cooling area 113, and by providing the isolation door, the isolation door may play a role of isolating the atmosphere, and when the sealing material is poor, the isolation door may effectively prevent the atmosphere gas in the heating chamber 120 from leaking to the cooling area 113 side. When carbon monoxide is used in the carburizing gas for CP control, leakage of carbon monoxide to the cooling zone 113 is avoided.

In the present embodiment, the carbon potential control device 140 includes a carbon potential measuring instrument 141 and a carbon potential control valve 143, the carbon potential measuring instrument 141 is provided in the heating chamber 120 to measure the carbon potential in the heating chamber 120, the carbon potential control valve 143 is connected to the carbon potential measuring instrument 141, the heating chamber 120 is provided with a carburizing gas introduction port 161, the carburizing gas introducing device 160 is connected to the carburizing gas introduction port 161, and the carbon potential control valve 143 is provided in the carburizing gas introduction port 161 to control the flow rate of the carburizing gas introduced into the heating chamber 120. Specifically, the carbon potential control valve 143 is an electromagnetic valve which is provided at the carburizing gas introduction port 161 and is controlled by the measurement result of the carbon potential measuring instrument 141, that is, when the carbon potential measuring instrument 141 measures that the carbon potential in the heating chamber 120 is too high, the flow rate of the carburizing gas can be reduced by the carbon potential control valve 143, thereby reducing the carbon potential in the heating chamber 120, or the control process is reversed. The carbon potential in the heating chamber 120 can be effectively controlled by the carbon potential control device 140, so that CP control can be performed at the final stage of vacuum carburization, the uneven surface carbon concentration can be greatly alleviated, the generation of retained austenite is avoided, and the product quality is greatly improved. The carbon potential measuring instrument 141 may measure the carbon potential by measuring the carbon dioxide content in the furnace, for example, by measuring the oxygen content in the furnace by an oxygen probe, and further measure the carbon potential. Of course, the specific structure and measurement principle of the carbon potential measuring instrument 141 may also refer to the existing carbon potential measuring equipment, and is not limited in detail here.

Referring to fig. 4, the present embodiment also provides a composite carburizing process, which is applicable to the aforementioned composite carburizing apparatus 100. The process method comprises the following steps:

s1: the product is placed in the cooling zone 113 of the carburizing furnace body 110.

Specifically, the front door 117 is opened, the product is put on the internal conveyance device 115 in the cooling zone 113, and then the front door 117 is closed, so that the whole carburizing furnace body 110 is in a sealed state.

S2: the carburizing furnace body 110 is subjected to vacuum pumping.

Specifically, after the front door 117 is closed, the entire carburizing furnace body 110 is vacuumized by the second vacuum-pumping device 190, so that the entire carburizing furnace body 110 is in a vacuum state. Specifically, the inside of the carburizing furnace body 110 may be evacuated to a predetermined value, and the vacuum exhaust valve may be closed for a predetermined period of time. A change in the degree of vacuum can be confirmed here in order to check for a vacuum leak. If the vacuum degree is not changed within the prescribed time, the next step is proceeded to. Otherwise, an alarm is given to check.

When the carburizing furnace body 110 is vacuumized, if the heating chamber 120 and the carburizing furnace body 110 are in a state of being entirely communicated, the heating chamber 120 can be ensured to be vacuumized together. Alternatively, the heating chamber 120 may be vacuumized by the first vacuum pumping device 130.

S3, the product is loaded into the heating chamber 120 in a vacuum state.

Specifically, the heating door 123 is opened, the product is conveyed into the heating chamber 120 by the internal conveyance device 115, and then the heating door 123 is closed.

S4: the heating chamber 120 in the vacuum state is heated to heat the product.

In particular, the first heating step is first of all heated in a vacuum, with the aim of removing the vapours that adhere to the surface of the product. The second heating step employs a selection system. During energy-saving operation, the second heating step is vacuum heating. In the case of operation in a short time, an inert gas (nitrogen gas) is introduced into the heating chamber 120 from the blowing port, and the convection fan 121 is started to perform convection heating. At this time, the pressure of the gas is preferably controlled to about 80kPa so that the pressure in the furnace does not exceed 101kPa (atmospheric pressure) even if the pressure in the furnace is increased by thermal expansion of the heated gas. In order to avoid the leakage of the sealing part, the input gas is sealed, and no atmosphere is added at ordinary times.

S5: a soaking heating chamber 120.

Specifically, the soaking step is the same as the heating step to ensure uniformity of heating.

S6: the carburizing gas is introduced into the heating chamber 120 by the carburizing gas introduction device 160 to carburize the product.

Specifically, after soaking for a certain period of time, the carburizing step is performed, and in the carburizing step, in order to use the carburizing gas used in the conventional vacuum carburizing, after the soaking step is completed, the furnace is set in a vacuum state, and the vacuum state is naturally maintained if the furnace is heated in vacuum, and the vacuum-pumping treatment is performed again if the furnace is heated in convection. Thereafter, the carburizing gas is introduced from the carburizing gas introduction port 161. In the case of using acetylene gas, it is preferable to control the pressure to be equal to or lower than the pressure (200Pa or lower) at which the viscous flow region of the vacuum is switched to the intermediate region. If the characteristics of the molecular flow are slightly affected, the treated product can freely enter and exit with a gap therebetween, and the occurrence of the carburized streaks can be reduced.

After the carburizing step, a diffusion step may be performed, and the diffusion step is a selected value, and may be an inert atmosphere or a vacuum atmosphere, and specifically, reference may be made to a conventional diffusion process.

S7: the heating chamber 120 is slowly cooled, and the carbon potential in the heating chamber 120 is controlled by the carbon potential control device 140, so that the carbon concentration on the surface of the product is uniformly distributed.

Specifically, in the slow cooling step, vacuum evacuation is performed under an inert gas atmosphere. The inside of the carburizing furnace body 110 is kept in a vacuum state, thereby removing impurity components as much as possible. The following is described by drop-cast carburization: methanol is put into a high-temperature portion of the furnace and gasified. In addition, in order to form the target CP, methanol may be fed together with the enriched gas. In the case of the drop-on-demand type, the temperature in the furnace tends to decrease due to the latent heat of vaporization of methanol, and therefore, it is preferable to adjust the atmosphere in the slow cooling step. After the atmosphere is adjusted, CP control is performed using a sensor such as the carbon potential measuring instrument 141. The sensor may be an oxygen probe for oxygen content management and CP control. The infrared analysis manages the amount of carbon dioxide, and CP control is performed by the carbon potential control valve 143. The slow cooling step and soaking before quenching also continue CP control.

And after the set CP control time is finished, carrying out vacuum exhaust in the furnace once.

S8: the product is cooled.

The cooling step may be selected from various types, and in the case of oil cooling, the cooling step is selected from the group consisting of furnace pressures (e.g., 70kPa, 50kPa, 30kPa, and 10 kPa). Note that the pressure here is at most not close to atmospheric pressure. The reason is that the heated product will generate oil smoke when put into the oil, and thus the pressure in the furnace will rise instantaneously. And if the pressure is below 1 atmosphere, the oil smoke can not be discharged out of the furnace. When the pressure is high, the temperature at which the vapor film is cut is high, and therefore, the cooling capacity of the processed product at high temperature is high. However, in transporting the treatment product, in addition to increasing radiation heat dissipation, the amount of heat generated by convection increases with increasing pressure. On the other hand, the vacuum side is cooled slowly because the temperature at which the vapor film is cut off becomes low in the high-temperature portion. However, convection heat dissipation is small. As a countermeasure against the soot, the air-cooling device 180 may be activated, and the flying soot is cooled to reduce the raised internal pressure of the furnace.

In summary, the present embodiment provides a composite carburizing apparatus 100 and a composite carburizing process, in which a heating zone 111 and a cooling zone 113 are disposed in a carburizing furnace body 110, a heating chamber 120 is disposed in the heating zone 111, a first vacuumizing device 130 is connected to the heating chamber 120 for vacuumizing the heating chamber 120, and a carburizing gas introducing device 160 is connected to the heating chamber 120 and introduces carburizing gas into the heating chamber 120 in a vacuum state, so as to achieve vacuum carburizing of a product. In addition, the present invention is additionally provided with a carbon potential control device 140, and the carbon potential control device 140 is arranged in the heating chamber 120 and is used for controlling the carbon potential in the heating chamber 120 so as to make the carbon concentration uniformly distributed on the surface of the product. Compared with the conventional carburizing technology, the carbon potential control device 140 is additionally arranged in the embodiment, so that the carbon potential in the heating chamber 120 can be controlled, the CP control can be performed at the final stage of the vacuum carburizing, the uneven surface carbon concentration can be greatly alleviated, the generation of residual austenite is avoided, and the product quality is greatly improved.

The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.