JPH03193863A - Continuous type gas carburization furnace - Google Patents

Abstract

PURPOSE:To obtain an adequate carburization depth by determining a carbon potential(CP) from the detected values of the carburizable gas quantity, oxygen quantity and temp. of the respective zones for heating up, carburizing and diffusing in a carburization chamber and comparing the detected values with set values thereby controlling the CP to the optimum value. CONSTITUTION:The inside of the carburization chamber 3 of the above furnace 1 having a chamber 2 for introducing the articles to be treated, the carburization chamber 3 and a quenching oil chamber 4 is divided to the heating up zone 3A, the carburizing zone 3B and the diffusing zone 3C. The CP value of the zone 3B is determined by a computing element 26 in accordance with the detection signals from an IR type CO analyzer 23, a zirconia type O2 analyzer 24 and a thermocouple 25. This value is corrected and is sent to a controller 28 by which the value is compared with the set CP value. Supply rate controllers 20, 21 for the rates of the air and gaseous raw materials to be supplied into the carburization chamber 3 are controlled in accordance with the deviation between both. The atmosphere in the zone 3B is maintained at the CP value adequate for obtaining the desired carburization depth. The atmospheres in the zones 3A, 3C are similarly controlled.

Description

[Detailed Description of the Invention] Industrial Field of Application This invention is equipped with a carburizing chamber, an article introduction chamber, and a quenching oil chamber, and introduces air and raw material gas into the carburizing chamber for transformation. The present invention relates to a continuous gas carburizing furnace that generates carburizing gas and performs carburizing treatment on articles to be treated.

Prior Art and Problems with the Invention Conventionally, a continuous gas carburizing furnace equipped with a carburizing chamber, an article introduction chamber, and a quenching oil chamber was used to generate carburizing gas in the carburizing chamber to apply carburizing treatment to the article. As a method of applying
2. Description of the Related Art There is a known method of carburizing an article by controlling the amount of air supplied while supplying a constant amount of raw material gas into a carburizing chamber. However, with this method, the amount of raw material gas may be excessive than the amount needed to obtain the carbon required for the article to be treated, and as a result, there is a problem that the surfaces of the furnace wall, heating device, etc. become catalytic. There is.

Also mentioned above. As such a carburizing method, there is also known a method in which the carburizing chamber has a closed structure and the amount of raw material gas supplied into the sealed carburizing chamber is controlled in accordance with the amount of articles to be treated. However, in the case of this method, when the amount of objects to be processed is small (as the amount of raw material gas also decreases, the gas flow in the carburizing furnace changes and the carburizing atmosphere becomes unstable, making it difficult to control the carburizing depth properly). There is a problem that it is not possible to
The amount of gas in the article introduction chamber and quenching oil chamber, which are connected to the carburizing chamber, also decreases, creating negative pressure inside the furnace, allowing air to enter from outside the furnace, and the atmosphere being disturbed by oxygen in the air. There is a problem that an appropriate carburizing depth cannot be obtained, sometimes causing an explosion in the introduction chamber or oil chamber.

An object of the present invention is to provide a continuous gas carburizing furnace that solves the above problems and can always obtain an appropriate carburizing depth.

Means for Solving the Problems A continuous gas carburizing furnace according to the present invention includes a carburizing chamber, an article introduction chamber, and a quenching oil chamber, and introduces air and raw material gas into the carburizing chamber for transformation. This is a continuous gas carburizing furnace that generates carburizing gas and performs carburizing treatment on the article to be treated, in which a temperature raising zone, a carburizing zone, and a diffusion zone in the carburizing chamber are respectively configured to provide an air supply means, a raw material gas supply means, and a carbon Each carbon potential control means includes a supply amount controller provided in the oxygen supply means and the raw material gas supply means, and a carburizing gas detection means for detecting the amount of carburizing gas in the carburizing chamber. ,
Oxygen detection means detects the amount of oxygen in the carburizing chamber, temperature detection means detects the temperature of the carburizing chamber, carbon potential inside the carburizing chamber is determined based on output signals from the raw material gas detection means, the oxygen detection means, and the temperature detection means. a computing unit that computes;
A predetermined carbon potential is set in advance, and the calculated value of the calculator is compared with the set value, and based on the deviation between the two, the supply amount controllers of the oxygen supply means and the raw material gas supply means are driven to adjust the oxygen supply amount. and a regulator for adjusting the amount of raw material gas supplied.

Carbon potential of each zone (hereinafter referred to as CP)
The carburizing gas detection means in the control means detects the amount of carburizing gas in each zone in the carburizing chamber, the oxygen detection means detects the amount of oxygen in each zone in the carburizing chamber, and the temperature detection means detects the amount of carburizing gas in each zone in the carburizing chamber. Detects the temperature of Based on the output signals from these detection means, each computing unit computes the carbon potential.

Then, the regulator of each control means compares a predetermined setting CP value preset in the regulator with the calculated CP value of the calculator, and based on the deviation between the two, the oxygen supply means of each zone and the source gas The supply amount controller of the supply means is driven to adjust the oxygen supply amount and the raw material gas supply amount. That is,
When the calculated value calculated by the calculator is smaller than the set value, the amount of raw material gas supplied to the carburizing chamber is increased and the amount of oxygen is decreased. On the contrary, when the calculated value is larger than the set value, the amount of raw material gas supplied to the carburizing chamber is decreased and the amount of oxygen is increased. thus,
The CP of each zone in the carburizing chamber can be controlled to an optimal value.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of a continuous gas carburizing furnace according to the present invention. In FIG. 1, a continuous gas carburizing furnace (1) includes, from the left side, an article introduction chamber (2), a carburizing chamber (3), and a quenching oil chamber (4).

Processing material introduction chamber (2) and outside the furnace, processing material introduction chamber (2)
) and carburizing chamber (3), carburizing chamber (3) and quenching oil chamber (4),
The quenching oil chamber (4) and the outside of the furnace each have movable doors (5).
It is separated by Inside the carburizing chamber (3), from the left side, there are a temperature increasing zone (3A), a carburizing zone (3B), and a diffusion zone (
3C). Each zone (3A) (aB)
(3C) are each equipped with an air supply source (7), a raw material gas supply source (8), and a CP control device (9). The air supply source (7) and the raw material gas supply source (8) are connected via conduits (10) and (11), respectively, to a mixed gas supply pipe (12) whose one end is connected to the furnace wall. and,
The article to be treated (S) that has entered the carburizing chamber (3) via the introduction chamber (2) is transferred to the carburizing chamber (3) by a transport device (not shown).
The material is transported from the temperature raising zone (3A) to the diffusion zone (3C), during which it is heated to a predetermined temperature in the temperature raising zone (3A), carburized in the carburizing zone (3B), and then transported to the diffusion zone (3C). In the carburizing zone (3B), diffusion treatment is performed at a temperature lower than that in the carburizing zone (3B).After that, the quenching oil chamber (4B)
) is subjected to hardening treatment.

Each CP control device (9) has a similar configuration, and the CP control device (9) in the carburizing zone (3B) will be explained with reference to FIG. In FIG. 2, the CP control device (9) is
A conduit (lO) connecting the air supply source (7) and the mixed gas supply pipe (12) and a conduit (11) connecting the raw material gas supply [(8) and the mixed gas supply pipe (12) are provided, respectively. A supply rate controller (20) (21) consisting of a mass flow controller, a control valve, etc., and a sampling tube (2) for collecting the atmosphere inside the carburizing chamber (3).
2) and an infrared CO gas analyzer (23) that measures the CO concentration in the atmosphere collected by the sampling tube (22) and converts it into an electrical signal, and an infrared CO gas analyzer (23) that measures the 02 concentration in the carburizing chamber (3) and converts it into an electrical signal. It is equipped with a zirconia type 02 analyzer (24) that converts into 02 and a thermocouple (25).

Based on the detection signals sent from the CO gas analyzer (23), 02 analyzer (24), and thermocouple (25), the CP value of the carburizing zone (3B) is logically operated in the calculator (26). The CP value is determined. The calculated CP value is calculated using a corrector (2
7), the signal is corrected so as to approximate the actual value determined experimentally, and is output as a corrected CP multiplied signal. Correction CP double signal, controller (28
) will be sent to. The set CP value is determined according to the required performance depending on the type of the article to be processed (S). Then, in the controller (28), the corrected calculated CP value and the set CP value are compared, and the supply amount controllers (20) (21) are driven based on the deviation between the two, and the inside of the carburizing chamber (3) is The air supply amount and raw material gas supply amount are adjusted. As a result, the atmosphere in the carburizing zone (3B) is maintained at an atmosphere that can maintain an appropriate CP value to obtain the desired carburizing depth. When butane gas is used as the raw material gas, for example, the relationship between the magnitude of the output from the controller (28) and the raw material gas supply amount and air supply amount is as shown in FIG. This relationship is determined in advance through experiments in accordance with the volume of the carburizing chamber (3), the type of raw material gas, the weight and surface area of the article to be treated (S), and the like.

The atmosphere in the temperature increasing zone (3A) and the diffusion zone (3C) is also maintained at an appropriate C as in the case of the carburizing zone (3B) mentioned above.
The atmosphere is maintained to maintain the P value.

In the above embodiment, the calculated CP value calculated by the calculating unit (26) is corrected by the corrector (27) so as to approximate the actual value determined by experiment, and the corrected CP value is calculated by the controller (27). 28) Although the set CP value that has been set is compared, the corrector (27) is not necessarily required. In addition, in the above embodiment, the CO concentration in the atmosphere is measured with an infrared CO gas analyzer (23),
The concentration is measured with a zirconia type 02 analyzer (24), and the temperature is measured with a thermocouple (25).
It is not limited to this.

Effects of the Invention According to the continuous gas carburizing furnace of the present invention, as described above, the temperature increase in the carburizing chamber, and the CP of each zone of carburizing and diffusion are controlled.
can be controlled to the optimum value. Therefore, a carburized layer having an appropriate carburizing depth can be formed on the surface of the article to be treated.

Furthermore, since the CP value of the atmosphere in the carburizing chamber is maintained at an optimal value, it is possible to prevent the surfaces of the furnace walls, heating devices, etc. from being catalyzed, and it is also possible to prevent explosions due to excess air in the introduction chamber and the quenching oil chamber.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the entire carburizing furnace showing an embodiment of the present invention, Figure 2 is a diagram showing the configuration of the CP control device in the carburizing zone of the carburizing furnace, and Figure 3 is the magnitude of the output from the controller. Sato,
It is a graph showing the relationship between the raw material gas supply amount and the air supply amount. (1)...Continuous gas carburizing furnace, (2)...Product introduction chamber, (3)...Carburizing chamber, (3A)...Temperature rising zone, (3B)...Carburizing zone, (3C)...diffusion zone, (4)...quenching oil chamber, (7)...air supply source, (8)...raw material gas supply source, (9)...cp
Control device, (20) (21)... Supply amount controller, (2
3)... Infrared type CO gas analyzer, (24)... Zirconia type 02 analyzer, (25)... Thermocouple, (26
)...Arithmetic unit, riz8)...Controller. that's all

Claims (1)

[Scope of Claims] The carburizing chamber is equipped with a carburizing chamber, an article introduction chamber, and a quenching oil chamber, and a carburizing gas is generated by introducing air and raw material gas into the carburizing chamber and transforming the article. It is a continuous gas carburizing furnace that performs carburizing treatment on carbon, and the temperature raising zone, carburizing zone, and diffusion zone in the carburizing chamber are each equipped with an air supply means, a raw material gas supply means, and a carbon potential control means, and each carbon potential is The control means includes a supply amount controller provided in each of the oxygen supply means and the raw material gas supply means, and a carburizing gas detection means for detecting the amount of carburizing gas in the carburizing chamber.
Oxygen detection means detects the amount of oxygen in the carburizing chamber, temperature detection means detects the temperature of the carburizing chamber, carbon potential inside the carburizing chamber is determined based on output signals from the raw material gas detection means, the oxygen detection means, and the temperature detection means. a computing unit that computes;
A predetermined carbon potential is set in advance, and the calculated value of the calculator is compared with the set value, and based on the deviation between the two, the supply amount controllers of the oxygen supply means and the raw material gas supply means are driven to adjust the oxygen supply amount. A continuous gas carburizing furnace consisting of a controller and a regulator that adjusts the raw material gas supply amount.