CN117626168A - Carburizing gas control method and system for vacuum carburization - Google Patents
Carburizing gas control method and system for vacuum carburization Download PDFInfo
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- CN117626168A CN117626168A CN202311701799.2A CN202311701799A CN117626168A CN 117626168 A CN117626168 A CN 117626168A CN 202311701799 A CN202311701799 A CN 202311701799A CN 117626168 A CN117626168 A CN 117626168A
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- carburizing
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- 238000005255 carburizing Methods 0.000 title claims abstract description 194
- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000010438 heat treatment Methods 0.000 claims abstract description 12
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 claims description 27
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 claims description 27
- 238000004891 communication Methods 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 abstract description 4
- 239000007789 gas Substances 0.000 description 135
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 16
- 239000001257 hydrogen Substances 0.000 description 16
- 229910052739 hydrogen Inorganic materials 0.000 description 16
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 14
- 229910052799 carbon Inorganic materials 0.000 description 14
- 238000006243 chemical reaction Methods 0.000 description 9
- 229910000831 Steel Inorganic materials 0.000 description 6
- 239000010959 steel Substances 0.000 description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 239000006104 solid solution Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Abstract
The embodiment of the invention provides a carburizing gas control method and a system for vacuum carburization, which relate to the technical field of heat treatment, wherein a vacuum carburization process is adopted to introduce carburizing gas into a carburizing furnace in a vacuum state to carry out carburization, then the concentration of the carburizing gas in the gas discharged from a carburizing chamber is detected outside the carburizing chamber, the initial concentration is set in an initial state, then the introduction flow of the carburizing gas is controlled according to the difference value of the concentration of the carburizing gas relative to the initial concentration, and the concentration of the carburizing gas in the discharged gas can well reflect the carburization process, so that the introduction amount of the carburizing gas can be controlled accordingly, and the introduction amount of the carburizing gas is reduced in the rear section. Compared with the prior art, the invention determines the reaction time by measuring the concentration of the carburizing gas in the exhaust gas, and controls the amount of the introduced carburizing gas, thereby reliably and safely reducing the amount of the carburizing gas.
Description
Technical Field
The invention relates to the technical field of heat treatment, in particular to a carburizing gas control method and a carburizing gas control system for vacuum carburization.
Background
Vacuum carburization is performed so that the surface carbon content increases to the carbon solid solution limit point (A3-Acm point) at the carburization temperature. Thereafter, carbon diffuses into the steel material. When the surface carbon concentration is at the solid solution limit point, the surface is not changed temporarily, but carbon starts to precipitate gradually thereafter. The gas generated by the reaction of vacuum carburization using acetylene with steel is only hydrogen. As shown by the reaction curve of acetylene gas, the reaction rate of acetylene gas is faster than other gases. Therefore, hydrogen gas is generated in a short time after carburization. The amount of hydrogen gas increases according to the surface area ratio of the treated article. The amount of hydrogen is large before the treated product reaches the carbon solid solution limit point. However, when this is achieved, the amount of hydrogen decreases sharply. As described above, this is because carbon diffuses into the steel material. The amount of acetylene introduced as a carburizing gas can be reduced at this time to save the amount of gas. However, since it is difficult to detect this change point, the amount of acetylene gas introduced does not change at the time of conventional carburization.
In recent years, it has been proposed to determine the change point by measuring the amount of reaction hydrogen in the furnace with respect to the change in the amount of acetylene gas introduced, however, such a method has an excessive influence factor, and the amount of hydrogen changes depending on the shape of the article to be processed, and the method reacts with tools, trays, and the like inserted together with the article to be processed, and also reacts with the structures in the furnace, thereby becoming an uncertain factor other than the article to be processed. Because of the uncertainty factors, the determination of the drop point of the reaction hydrogen simply by the temperature parameter or the hydrogen content is inaccurate, so that the control of the introduction amount of acetylene gas is difficult to realize accurately, and the carburization effect is affected.
Disclosure of Invention
The present invention has an object to provide a carburizing gas control method and system for vacuum carburization, which can determine the reaction timing by measuring the concentration of a carburizing gas in an exhaust gas, and control the amount of the carburizing gas introduced by this, thereby reliably and safely reducing the amount of the carburizing gas used.
Embodiments of the invention may be implemented as follows:
in a first aspect, the present invention provides a carburizing gas control method of vacuum carburization, comprising:
introducing carburizing gas into the carburizing chamber under the vacuum state;
detecting a carburizing gas concentration in a gas discharged from the carburizing chamber outside the carburizing chamber, and setting an initial concentration;
and controlling the inflow flow of the carburizing gas according to the difference value of the concentration of the carburizing gas relative to the initial concentration.
In an alternative embodiment, the step of detecting the carburizing gas concentration in the gas discharged from the carburizing chamber outside the carburizing chamber, and setting the initial concentration includes:
detecting the concentration of the carburizing gas in the exhaust pipe of the carburizing chamber after a preset time T is reserved after the exhaust pipe of the carburizing chamber starts exhausting;
the carburizing gas concentration measured in the initial state is taken as an initial concentration.
In an alternative embodiment, the preset time T is 30-60s.
In an alternative embodiment, the carburizing gas is acetylene gas.
In an alternative embodiment, the step of controlling the flow rate of the carburizing gas according to the difference between the carburizing gas concentration and the initial concentration includes:
and when the concentration of the carburizing gas rises by A% relative to the initial concentration, reducing the introducing flow A% of the carburizing gas.
In alternative embodiments, a% is between 20% -30%.
In an alternative embodiment, before the step of introducing the carburizing gas into the carburizing chamber under vacuum, the method further includes:
heating the carburizing furnace and vacuumizing the carburizing furnace.
In a second aspect, the present invention provides a carburizing gas control system for vacuum carburization, which is suitable for the carburizing gas control method for vacuum carburization according to the foregoing embodiment, and includes a carburizing furnace, an air intake pipe connected to a top end of the carburizing furnace for introducing a carburizing gas into the carburizing furnace, an exhaust pipe connected to a bottom end of the carburizing furnace, a vacuum pump provided on the exhaust pipe for extracting the gas in the carburizing furnace through the exhaust pipe, a concentration sensor provided on the exhaust pipe for detecting a concentration of the carburizing gas in the gas discharged from the carburizing chamber and setting an initial concentration, and an air intake control valve provided on the air intake pipe and communicatively connected to the concentration sensor for controlling a flow rate of the carburizing gas in accordance with a difference between the concentration of the carburizing gas and the initial concentration.
In an alternative embodiment, the intake control valve is configured to reduce the flow rate of the carburizing gas by a% when the carburizing gas concentration increases by a% relative to the initial concentration.
In an alternative embodiment, a heating pipe is further arranged in the carburizing furnace, and the heating pipe is used for heating the carburizing furnace.
The beneficial effects of the embodiment of the invention include, for example:
according to the carburizing gas control method and system for vacuum carburization, a vacuum carburization process is adopted, carburization gas is introduced into a carburizing furnace in a vacuum state, carburization is performed, the concentration of the carburization gas in the gas discharged from a carburization chamber is detected outside the carburizing chamber, initial concentration is set in an initial state, then the introduction flow of the carburization gas is controlled according to the difference value of the concentration of the carburization gas relative to the initial concentration, and the concentration of the carburization gas in the discharged gas can well reflect the carburization process, so that the introduction amount of the carburization gas can be controlled accordingly, and the introduction amount of the carburization gas is reduced in the later stage. Compared with the prior art, the invention determines the reaction time by measuring the concentration of the carburizing gas in the exhaust gas, and controls the amount of the introduced carburizing gas, thereby reliably and safely reducing the amount of the carburizing gas.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a carburizing gas control system for vacuum carburization according to an embodiment of the present invention;
fig. 2 is a block diagram of steps of a carburizing gas control method for vacuum carburization according to an embodiment of the present invention.
Icon: 100-a carburizing gas control system for vacuum carburization; 110-carburizing furnace; 120-air inlet pipe; 130-exhaust pipe; 140-a vacuum pump; 150-concentration sensor; 160-an intake control valve; 170-heating tube.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the 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 invention, as 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 made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the present invention, it should be noted that, if the terms "upper", "lower", "inner", "outer", and the like indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, or the azimuth or the positional relationship in which the inventive product is conventionally put in use, it is merely for convenience of describing the present invention and simplifying the description, and it is not indicated or implied that the apparatus or element referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus it should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, if any, are used merely for distinguishing between descriptions and not for indicating or implying a relative importance.
As disclosed in the background art, even if a sufficient amount of carburizing gas is fed during the carburizing process, the rate of carbon penetration into the steel material does not change, and therefore, the amount of carburizing gas introduced can be reduced appropriately after exceeding the critical point. In the prior art, when acetylene gas is used as carburizing gas, the reaction timing (i.e., critical point) is usually determined by measuring the hydrogen concentration, however, the measurement of the hydrogen concentration needs to be performed in a furnace, and this measurement method has a large influence on the shape of the processed article, the tool and the tray, and part of the structure also reacts with hydrogen in the furnace, so that the measurement is inaccurate due to a plurality of uncertain factors.
In addition, the pressure of general vacuum carburization is 300Pa or less, and it is difficult to measure the hydrogen amount with high accuracy in this vacuum region. In addition to acetylene/hydrogen, nitrogen is mixed into the furnace gas, and the nitrogen is used for placing carbon deposit to be adsorbed on the electrode part, so that the measurement of the hydrogen concentration is easily affected, and the adjustment of the amount of carburizing gas according to the amount of hydrogen change is difficult. The general hydrogen sensor is heat conduction type, and has extremely poor precision below 300 Pa. And the installation in the furnace is difficult and gas leakage is easy to occur.
In the pulse carburization method, the pressure in the furnace always varies continuously, and therefore, it is more difficult to measure the amount of hydrogen.
In order to solve the above problems, the present invention provides a novel carburizing gas control method for vacuum carburization, which can determine the reaction timing with a new detection target and can accurately and reliably reduce the amount of carburizing gas used. It should be noted that the features of the embodiments of the present invention may be combined with each other without conflict.
Referring to fig. 1, the present embodiment provides a carburizing gas control system 100 for vacuum carburization, which can determine the reaction time by measuring the concentration of the carburizing gas in the exhaust gas, and thus control the amount of the introduced carburizing gas, so as to reliably and safely reduce the amount of the carburizing gas.
The carburizing gas control system 100 for vacuum carburization provided in this embodiment includes a carburizing furnace 110, an air inlet pipe 120, an air outlet pipe 130, a vacuum pump 140, a concentration sensor 150 and an air inlet control valve 160, the air inlet pipe 120 is connected to the top end of the carburizing furnace 110 for introducing carburizing gas into the carburizing furnace 110, the air outlet pipe 130 is connected to the bottom end of the carburizing furnace 110, the vacuum pump 140 is arranged on the air outlet pipe 130 for pumping out gas in the carburizing furnace 110 through the air outlet pipe 130, the concentration sensor 150 is arranged on the air outlet pipe 130 for detecting the concentration of carburizing gas in the gas discharged from the carburizing chamber and setting an initial concentration, and the air inlet control valve 160 is arranged on the air inlet pipe 120 and is in communication connection with the concentration sensor 150 for controlling the introducing flow of the carburizing gas according to the difference between the concentration of the carburizing gas and the initial concentration.
In this embodiment, the carburizing furnace 110 is provided with a product to be treated, and the air inlet pipe 120 is used for introducing a carburizing gas, which may be acetylene gas, and the introducing manner may refer to the existing vacuum carburizing process. The concentration sensor 150 is disposed on the exhaust side of the vacuum pump 140, and is capable of accurately measuring the concentration of acetylene gas in the exhaust gas, and setting the initial concentration at the initial measurement stage, so that the gas inlet control valve 160 can compare the concentration difference, and timely reduce the amount of the introduced carburizing gas according to the concentration change condition of the acetylene gas.
At the time of the change in the acetylene gas concentration in the discharged gas, the surface carbon concentration of the treated article was close to the Acm (critical) point. The Acm point is almost reached when the acetylene gas concentration increases by about 10%. The carburizing gas flow rate required for internal diffusion is 5 or less times the conventional flow rate alone, relative to the carburizing gas flow rate required before the object to be treated reaches Acm, so that the flow rate of the carburizing gas can be appropriately reduced. The carburizing gas flow rate is approximately proportional to the surface area of the treated article.
In the present embodiment, the intake control valve 160 is configured to reduce the flow rate a% of the carburizing gas when the carburizing gas concentration rises by a% relative to the initial concentration. Wherein a% is set to between 20% and 30%, that is, when the concentration sensor 150 detects an increase in the acetylene gas concentration by 20% to 30% relative to the initial concentration, the inflow rate of acetylene gas can be reduced by 20% to 30% by the inlet control valve 160. Compared with the mode of not changing the flow rate of acetylene gas during carburization in the conventional technology, the flow rate of acetylene gas is safely reduced by 20-30% after the surface carbon concentration of the treated product reliably reaches the Acm point, so that the amount of acetylene gas can be reliably reduced.
In the present embodiment, a heating pipe 170 is further disposed in the carburizing furnace 110, and the heating pipe 170 is used to heat the carburizing furnace 110. The temperature control mode is the same as the conventional carburizing process, and is not described herein.
Referring to fig. 2, the present embodiment also provides a carburizing gas control method for vacuum carburization, which is applicable to the foregoing carburizing gas control system 100 for vacuum carburization, and includes the following steps:
s1: and introducing a carburizing gas into the carburizing chamber under the vacuum state.
Specifically, before introducing the carburizing gas, the carburizing furnace 110 is heated and vacuumized, and then the carburizing gas, which may be acetylene gas, is introduced according to a preset flow rate, so as to complete the conventional carburizing process.
Generally, the base material carbon concentration of carburizing steel is 0.15 to 0.25%, the Acm point of a general carburizing steel is about 1.2% (930 ℃), and when a sufficient carburizing gas is supplied to the surface area of the article to be treated at a general carburizing temperature (920 to 960 ℃), the time for the surface carbon concentration to reach the Acm point is about 3 minutes at a high temperature. The temperature is 10 minutes or more at 930 ℃ which is the common carburization temperature.
S2: the carburizing gas concentration in the gas discharged from the carburizing chamber is detected outside the carburizing chamber, and the initial concentration is set.
Specifically, the concentration of carburizing gas in the exhaust pipe 130 of the carburizing chamber is detected after a preset time T after the exhaust pipe 130 of the carburizing chamber starts to exhaust, wherein the preset time T may be 30s to 60s.
In the early stage of carburizing, the carburizing gas is sometimes discharged without reaction after the introduction of the carburizing gas, and therefore, the concentration of acetylene gas is measured more accurately after 30s to 60s after the introduction of the carburizing gas.
S3: and controlling the inflow rate of the carburizing gas according to the difference value of the concentration of the carburizing gas relative to the initial concentration.
Specifically, when the carburizing gas concentration rises by a% relative to the initial concentration, the introduction flow rate a% of the carburizing gas is reduced, wherein a% is between 20% -30%. That is, in the carburizing process, when the acetylene gas concentration is increased by 20% to 30% relative to the initial concentration, the amount of acetylene gas input can be reduced by 20% to 30%, so that the acetylene gas reduction flow rate can be safely reduced by 20% to 30% even after the surface carbon concentration of the workpiece reliably reaches the Acm point, and the acetylene gas amount can be reliably reduced.
In summary, the method and system for controlling carburizing gas in vacuum carburization firstly adopts a vacuum carburization process, and is characterized in that the carburizing gas is introduced into a carburizing furnace 110 in a vacuum state to perform carburization operation, then the concentration of the carburizing gas in the gas discharged from a carburizing chamber is detected outside the carburizing chamber, the initial concentration is set in an initial state, and then the introduction flow rate of the carburizing gas is controlled according to the difference value of the concentration of the carburizing gas relative to the initial concentration. Compared with the prior art, the embodiment determines the reaction time by measuring the concentration of the carburizing gas in the exhaust gas, and controls the amount of the introduced carburizing gas, so that the amount of the carburizing gas can be reliably and safely reduced.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present invention should be included in the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. A carburizing gas control method of vacuum carburization, comprising:
introducing carburizing gas into the carburizing chamber under the vacuum state;
detecting a carburizing gas concentration in a gas discharged from the carburizing chamber outside the carburizing chamber, and setting an initial concentration;
and controlling the inflow flow of the carburizing gas according to the difference value of the concentration of the carburizing gas relative to the initial concentration.
2. The method of controlling carburizing gas of vacuum carburization according to claim 1, wherein the step of detecting a carburizing gas concentration in the gas discharged from the carburizing chamber outside the carburizing chamber and setting an initial concentration includes:
detecting the concentration of the carburizing gas in the exhaust pipe of the carburizing chamber after a preset time T is reserved after the exhaust pipe of the carburizing chamber starts exhausting;
the carburizing gas concentration measured in the initial state is taken as an initial concentration.
3. The carburizing gas control method of vacuum carburization according to claim 2, wherein the preset time T is 30-60s.
4. The carburizing gas control method of vacuum carburization according to claim 1, wherein the carburizing gas is acetylene gas.
5. The method of controlling a carburizing gas of vacuum carburization according to claim 1, wherein the step of controlling the flow rate of the carburizing gas in accordance with the difference in the carburizing gas concentration with respect to the initial concentration comprises:
and when the concentration of the carburizing gas rises by A% relative to the initial concentration, reducing the introducing flow A% of the carburizing gas.
6. The method of controlling carburizing gas of vacuum carburization according to claim 5, wherein a% is between 20% and 30%.
7. The carburizing gas control method of vacuum carburization according to claim 1, further comprising, prior to the step of introducing the carburizing gas into the carburizing chamber in the vacuum state:
heating the carburizing furnace and vacuumizing the carburizing furnace.
8. A carburizing gas control system for vacuum carburization, which is adapted to the carburizing gas control method of claim 1, and is characterized by comprising a carburizing furnace, an air inlet pipe connected to the top end of the carburizing furnace for introducing the carburizing gas into the carburizing furnace, an air outlet pipe connected to the bottom end of the carburizing furnace, a vacuum pump provided on the air outlet pipe for drawing out the gas in the carburizing furnace through the air outlet pipe, a concentration sensor provided on the air outlet pipe for detecting the concentration of the carburizing gas in the gas discharged from the carburizing chamber and setting an initial concentration, and an air inlet control valve provided on the air inlet pipe and in communication with the concentration sensor for controlling the flow rate of the introducing of the carburizing gas in accordance with the difference between the concentration of the carburizing gas and the initial concentration.
9. The vacuum carburized carburizing gas control system of claim 8 wherein the gas inlet control valve is configured to reduce the flow rate of the carburizing gas by a% when the carburizing gas concentration rises by a% relative to the initial concentration.
10. The carburizing gas control system of claim 8 wherein a heating tube is further disposed within the carburizing furnace, the heating tube being used to heat the carburizing furnace.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311701799.2A CN117626168A (en) | 2023-12-11 | 2023-12-11 | Carburizing gas control method and system for vacuum carburization |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311701799.2A CN117626168A (en) | 2023-12-11 | 2023-12-11 | Carburizing gas control method and system for vacuum carburization |
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| CN117626168A true CN117626168A (en) | 2024-03-01 |
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| CN202311701799.2A Pending CN117626168A (en) | 2023-12-11 | 2023-12-11 | Carburizing gas control method and system for vacuum carburization |
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- 2023-12-11 CN CN202311701799.2A patent/CN117626168A/en active Pending
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