KR102466935B1 - Sulfnitriding heat treatment apparatus - Google Patents

Abstract

The invention of a nitriding heat treatment apparatus is disclosed. The needle nitriding heat treatment apparatus of the present invention includes: a needle nitriding furnace in which a needle nitriding gas is injected and the steel material is heated so that the steel material is surface-treated by the needle needle nitriding gas; An ammonia treatment unit connected to the chimney nitriding furnace and decomposing residual ammonia in the exhaust gas discharged from the chimney nitriding furnace; A sulfur removal unit connected to the ammonia treatment unit and removing sulfur from the exhaust gas discharged from the ammonia treatment unit; and a combustion unit connected to the sulfur removal unit and emitting exhaust gas discharged from the sulfur removal unit to the outside.

Description

Nitriding heat treatment apparatus {SULFNITRIDING HEAT TREATMENT APPARATUS}

The present invention relates to a nitriding heat treatment apparatus, and more particularly, to a nitriding heat treatment apparatus that does not require waste water treatment and is capable of changing the concentration of a needle gas.

In general, steel materials are subjected to thermochemical surface treatment to harden the surface. When a steel material is nitriding, a nitrogen compound layer and a diffusion layer are created on the surface of the steel material. As the steel material is nitriding, wear resistance and the like are improved.

There are two types of immersion nitrification: salt bath immersion nitriding and plasma immersion nitriding. The salt bath nitriding method has excellent productivity because the rate of formation of the chimney layer is fast, but the working environment is poor because it is a wet process. In addition, the salt bath nitriding method requires a cleaning process after salt bath nitriding treatment, and the process is complicated, such as a solid lubricant treatment, and wastewater treatment is required because the treated salt bath contains cyanide. In addition, since the plasma needle flow nitriding method significantly increases the cost of surface treatment and has poor productivity, it is difficult to apply to mass production of products.

The background art of the present invention is disclosed in Korean Patent Publication No. 2014-0022526 (published on February 25, 2014, title of the invention: nitriding method using plasma and nitriding product).

The present invention has been created to improve the above problems, and an object of the present invention is to provide a nitriding heat treatment apparatus that does not require wastewater treatment and can change the concentration of chimney gas.

A needle nitriding heat treatment apparatus according to the present invention includes: a needle nitriding furnace in which a needle nitriding gas is injected and the steel material is heated so that the steel material is subjected to surface treatment by the needle needle nitriding gas; An ammonia treatment unit connected to the chimney nitriding furnace and decomposing residual ammonia in the exhaust gas discharged from the chimney nitriding furnace; a sulfur removal unit connected to the ammonia treatment unit and removing sulfur from the exhaust gas discharged from the ammonia treatment unit; and a combustion unit connected to the sulfur removal unit and emitting exhaust gas discharged from the sulfur removal unit to the outside.

The nitriding furnace includes a heat treatment chamber in which the steel material is accommodated; a gas supply unit for supplying a nitriding gas to the heat treatment chamber unit; And it may include a heater unit for heating the steel material to surface-treat the steel material.

The gas supply unit may include a first supply pipe supplying ammonia to the heat treatment chamber unit; a second supply pipe supplying hydrogen sulfide to the heat treatment chamber; a third supply pipe supplying acetylene to the heat treatment chamber; and a fourth supply pipe supplying nitrogen to the heat treatment chamber unit.

An internal temperature of the heat treatment chamber unit may be maintained at 470-590°C.

The internal temperature of the ammonia treatment unit may be maintained at 800-900 °C.

The sulfur removal unit includes a casing into which the exhaust gas discharged from the ammonia treatment unit flows; a supporter unit disposed inside the casing; and a plurality of container units installed in the supporter unit and accommodating the emperor material.

The combustion unit may include an external housing connected to the sulfur removal unit; an inner housing disposed inside the outer housing and into which the exhaust gas discharged from the sulfur removal unit flows; and a burner installed in the outer housing to burn exhaust gas discharged from the inner housing to the outer housing.

The burner unit may include a burner body disposed to surround an upper side of the outer housing; and a plurality of injection nozzles disposed on the burner body to inject fuel gas onto the upper side of the outer housing.

According to the present invention, since the surface of the steel material is subjected to the nitriding process using the nitriding gas, it is possible to fundamentally prevent the generation of wastewater.

In addition, according to the present invention, since the ammonia treatment unit decomposes ammonia contained in the exhaust gas and the sulfur removal unit removes sulfur, pollutant-free air can be discharged into the atmosphere.

1 is a circuit diagram schematically showing a nitriding heat treatment apparatus according to an embodiment of the present invention.
2 is a side view schematically showing a sulfur removal unit in a nitride heat treatment apparatus according to an embodiment of the present invention.
3 is a perspective view schematically showing a sulfur removal unit in a nitride heat treatment apparatus according to an embodiment of the present invention.
4 is a side view schematically illustrating a combustion unit in a chloronic nitriding heat treatment apparatus according to an embodiment of the present invention.
5 is a plan view schematically illustrating a burner unit of a combustion unit in a nitriding heat treatment apparatus according to an embodiment of the present invention.
6 is a view schematically showing a steel material subjected to a nitride process in a needle nitride heat treatment apparatus according to an embodiment of the present invention.

Hereinafter, an embodiment of a nitriding heat treatment apparatus according to the present invention will be described with reference to the accompanying drawings. In the process of explaining the nitriding heat treatment apparatus, the thickness of lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of a user or operator. Therefore, definitions of these terms will have to be made based on the content throughout this specification.

1 is a circuit diagram schematically showing a nitride heat treatment apparatus according to an embodiment of the present invention, and FIG. 2 is a side view schematically showing a sulfur removal unit in a nitride nitride heat treatment apparatus according to an embodiment of the present invention. 3 is a perspective view schematically showing a sulfur removal unit in a nitriding heat treatment apparatus according to an embodiment of the present invention, and FIG. 4 is a side view schematically showing a combustion unit in a nitriding heat treatment apparatus according to an embodiment of the present invention, 5 is a plan view schematically showing a burner unit of a combustion unit in a needle nitriding heat treatment apparatus according to an embodiment of the present invention, and FIG. It is a schematic drawing.

Referring to FIGS. 1 to 6 , the spigot nitriding heat treatment apparatus 100 according to an embodiment of the present invention includes a spigot nitriding furnace 110, an ammonia treatment unit 130, a sulfur removal unit 140, and a combustion unit 150 ).

The chimney nitriding heating furnace 110 is injected with the chimney nitriding gas, and the chimney nitriding gas heats the steel material so that the chimney nitriding treatment is performed. The decomposition unit is connected to the chimney nitriding furnace 110 and decomposes ammonia in the exhaust gas discharged from the chimney nitriding furnace 110 . The sulfur removal unit 140 is connected to the ammonia treatment unit 130 and removes sulfur from the exhaust gas discharged from the ammonia treatment unit 130 . The combustion unit 150 is connected to the sulfur removal unit 140, burns the exhaust gas discharged from the sulfur removal unit 140, and discharges it to the outside.

Gas nitrification methods include a method using NH ₃ + H ₂ S mixed gas, a method using NH ₃ + sulfur vapor, a method using NH ₃ + endothermic gas + H ₂ S mixed gas, or CS ₂ . Hereinafter, a method using a mixed gas of NH ₃ + H ₂ S will be described as a standard.

Since the ammonia treatment unit 130 decomposes ammonia contained in the exhaust gas and the sulfur removal unit 140 removes sulfur, air from which contaminants are removed can be discharged.

The nitriding furnace 110 includes a heat treatment chamber 111 , gas supply units 115 to 118 , and a heater unit 113 . A steel material is accommodated in the heat treatment chamber 111 . The gas supply units 115 to 118 supply nitriding gas to the heat treatment chamber unit 111 . The heater unit 113 heats the steel material to form nitride on the surface of the steel material. The gas supply units 115 to 118 supply ammonia (NH ₃ ), hydrogen sulfide (H ₂ S), acetylene (C ₂ H ₂ ), and nitrogen (N ₂ ), respectively. The heater unit 113 is disposed on the upper and lower sides of the heat treatment chamber unit 111 to evenly heat the surface of the steel material.

The internal temperature of the heat treatment chamber 111 is maintained at 470-590°C. Therefore, nitriding gas can treat the surface of the steel material. At this time, a nitrogen diffusion layer, a nitrogen compound layer, and a chimney layer are formed from the inside to the surface of the steel material. In the nitrogen diffusion layer, ammonia and acetylene are mainly penetrated while diffusion, in the nitrogen compound layer, mainly ammonia is diffused and penetrated, and in the chimney layer, sulfur is mainly diffused and penetrated. The sediment layer is called a solid lubricating layer having seizing resistance (lubricity). Therefore, since the steel material is nitrided and softened at a temperature below the transformation point, thermal deformation of the steel material hardly occurs. In addition, it can be applied to the surface treatment of various types of steel materials.

The nitrogen diffusion layer is formed to be approximately 15-300 μm, the nitrogen compound layer is formed to be 0-20 μm, and the chimney layer is formed to be 1-3 μm. The thickness of the nitrogen diffusion layer, the nitrogen compound layer, and the chimney layer may be variously controlled by the concentrations and components of the hydrogen sulfide and ammonia gas, the temperature of the chimney nitriding furnace 110, and the like.

The gas supply units 115 to 118 include a first supply pipe 115 for supplying ammonia to the heat treatment chamber 111, a second supply pipe 116 for supplying hydrogen sulfide to the heat treatment chamber 111, and a heat treatment chamber ( 111) and a third supply pipe 117 for supplying acetylene, and a fourth supply pipe 118 for supplying nitrogen to the heat treatment chamber 111. A first supply valve 115a is installed in the first supply pipe 115, a second supply valve 116a is installed in the second supply pipe 116, and a third supply valve 117a is installed in the third supply pipe 117. is installed, and a fourth supply valve 118a is installed in the fourth supply pipe 118. Therefore, since the concentration of the gas supplied from the first supply pipe 115 to the fourth supply pipe 118 is adjusted as the first supply valve 115a to the second supply valve 116a are individually controlled, the The thickness can be appropriately adjusted according to the purpose or application of the steel material.

The internal temperature of the ammonia treatment unit 130 is maintained at 800-900 °C. The ammonia treatment unit 130 is connected to a first discharge pipe 121 connected to the chimney nitriding furnace 110, and a first discharge valve 121a is installed in the first discharge pipe 121. The ammonia treatment unit 130 may remove residual ammonia from the exhaust gas by spraying water at a high temperature. Therefore, since the exhaust gas is heated to a high temperature in the ammonia treatment unit 130, residual ammonia contained in the exhaust gas can be removed as the solubility of ammonia is remarkably increased. Therefore, environmental pollution can be prevented from occurring.

Reaction formula of ammonia gas and water: NH ₃ (g) + H ₂ O(l) → NH ₄ OH(aq)

The sulfur removal unit 140 is installed in the casing 141 into which the exhaust gas discharged from the ammonia treatment unit 130 flows, the supporter unit 145 disposed inside the casing 141, and the supporter unit 145, , and includes a plurality of container parts 146 in which emperor material is accommodated. At this time, the supporter parts 145 are arranged side by side in the vertical direction inside the casing 141, and the plurality of container parts 146 are stacked on the supporter part 145 at regular intervals in the vertical direction. Emperor macromaterials include iron oxide.

The sulfur removal unit 140 is connected to the ammonia treatment unit 130 through a second discharge pipe 122, and a second discharge valve 122a is installed in the second discharge pipe 122. The inner housing 155 is connected to the third discharge pipe 123 by the connection pipe 153, and the third discharge valve 123a is installed in the third discharge pipe 123.

A gas inlet 142 is formed on the upper side of the casing 141 to allow exhaust gas to flow in, and a gas outlet 143 is formed on the lower side of the casing 141 to discharge the exhaust gas of the casing 141 . The gas inlet 142 is connected to the second outlet pipe 122 and the gas outlet 143 is connected to the third outlet pipe 123 . Since the exhaust gas is introduced into the upper side of the casing 141 through the gas inlet 142 and then discharged to the lower side of the casing 141, the contact time between the exhaust gas and the iron oxide can be increased. Accordingly, as the reaction time between sulfur and iron oxide is increased, sulfur contained in the exhaust gas can be almost removed.

The combustion unit 150 includes an outer housing 151 connected to the sulfur removal unit 140 and an inner housing disposed inside the outer housing 151 and into which the exhaust gas discharged from the sulfur removal unit 140 flows ( 155), and a burner unit 160 installed on the outer housing 151 to burn exhaust gas discharged from the inner housing 155 to the outer housing 151 unit.

The inner space of the outer housing 151 is significantly wider than the inner space of the inner housing 155 . A gas passage hole 157 is formed in the inner housing 155 to communicate with the outer housing 151 . A plurality of gas passage holes 157 are formed along the circumference of the inner housing 155 .

Since the exhaust gas passes through the inner housing 155 and diffuses into the outer housing 151, and the burner unit 160 burns the exhaust gas on the upper side of the outer housing 151, the combustion efficiency of the exhaust gas can be improved. have.

The burner unit 160 includes a burner body unit 161 disposed to surround the upper side of the outer housing 151 and an injection nozzle disposed on the burner body unit 161 to inject fuel gas to the upper side of the external housing 151. (164). The burner body 161 is formed in an annular tube shape to surround the upper circumference of the outer housing 151 . A plurality of injection nozzles 164 are installed along the circumferential direction of the burner body 161 . Therefore, since the plurality of injection nozzles 164 inject the fuel gas toward the center of the burner body 161 to burn the exhaust gas diffused upward from the outer housing 151, the combustion efficiency of the exhaust gas can be improved. have.

In the chloronitridation heat treatment apparatus according to an embodiment of the present invention configured as described above, a more detailed description of chloronitride will be given.

Carburizing is to increase the amount of carbon near the surface by diffusing carbon from the surface of the steel material while heating low carbon steel with low carbon content to the austenite region (900-950 ° C) in a carburizing agent. When the carburized steel material is quenched, the carburized layer is hardened and wear resistance is increased. In addition, since the carbon content is small inside the steel material, toughness is maintained without quench hardening.

In carbonitriding, carbon and nitrogen are simultaneously diffused and penetrated, nitriding gas is mixed with nitrifying ammonia gas by several percent, and heated in atmospheric gas. The purpose of carburizing and quenching is to impart wear resistance and seizure resistance (lubrication) to steel materials.

Since the A1 transformation point of the Fe-C phase diagram goes down to the lower right in the nitriding treatment, it can be treated at a lower temperature than the carburizing treatment temperature, so it can be said that deformation and shrinkage of the heat-treated product are reduced. Depending on the processing conditions, it is also possible to make a heat treated product with extremely little deformation by martensitizing only the surface layer and creating a structure that is not quenched inside by immersion nitriding at a temperature below the A1 transformation point.

As the steel material is subjected to nitriding treatment, high hardness can be obtained by generating martensite containing carbon and nitrogen. Steel materials with poor hardenability, such as SPCC (cold rolled steel), SPHC (hot rolled steel), S15C (low carbon steel), SUM24L, etc., can penetrate and diffuse nitrogen, an element that improves hardenability, in addition to carbon on the steel surface. Therefore, a hardened layer is obtained by quenching. Therefore, since inexpensive materials can be used effectively, it can contribute to lowering the cost of components.

In addition, when alloy steel such as SCM is gas-carburized, grain boundary oxidation and an incompletely hardened layer inevitably appear on the surface. Therefore, if a small amount of ammonia gas is added to the carburizing atmosphere immediately before quenching, it is possible to reduce the incompletely hardened layer because nitrogen assists the hardenability near the surface.

Nitriding treatment is selectively applied to alloy steels such as SCr steel and SCM steel having good hardenability for the purpose of improving pitting resistance of gears and the like. Unlike carburizing, nitriding heat treatment can increase fatigue strength and pitting resistance by refinement of martensite by nitrogen effect, increase of temper softening resistance, and strain-induced martensitization of retained austenite.

The present invention has been described with reference to the embodiments shown in the drawings, but this is only exemplary, and those skilled in the art can make various modifications and equivalent other embodiments. will understand

Therefore, the true technical protection scope of the present invention should be determined by the claims.

100: immersion nitriding heat treatment device 110: heating furnace
111: heat treatment chamber unit 113: heater unit
115: first supply pipe 115a: first supply valve
116: second supply pipe 116a: second supply valve
117: third supply pipe 117a: third supply valve
118: fourth supply pipe 118a: fourth supply valve
121: first discharge pipe 121a: first discharge valve
122: second discharge pipe 122a: second discharge valve
123: third discharge pipe 123a: third discharge valve
130: ammonia treatment unit 140: sulfur removal unit
141: casing 142: gas inlet
143: gas discharge unit 145: supporter unit
146: container unit 150: combustion unit
151: outer housing 153: connector
155: inner housing 157: gas passage hole
158: drain valve 160: burner unit
161: burner body 164: injection nozzle
170: discharge duct part

Claims (8)

A chimney nitriding furnace in which a chimney nitriding gas is injected, and the chimney nitriding gas heats the steel material to treat the surface of the steel material;
an ammonia treatment unit connected to the chimney nitriding furnace and decomposing residual ammonia in the exhaust gas discharged from the chimney nitriding furnace;
a sulfur removal unit connected to the ammonia treatment unit and removing sulfur from the exhaust gas discharged from the ammonia treatment unit; and
A combustion unit connected to the sulfur removal unit and combusting exhaust gas discharged from the sulfur removal unit and discharging it to the outside;
The sulfur removal unit,
a casing into which the exhaust gas discharged from the ammonia treatment unit flows;
a supporter unit disposed inside the casing; and
It is installed in the supporter part and includes a plurality of container parts in which emperor material is accommodated.
According to claim 1,
The immersion nitriding furnace,
a heat treatment chamber in which the steel material is accommodated;
a gas supply unit for supplying a nitriding gas to the heat treatment chamber unit; and
Nitriding heat treatment apparatus comprising a heater for heating the steel material to surface-treat the steel material.
According to claim 2,
The gas supply unit,
a first supply pipe supplying ammonia to the heat treatment chamber;
a second supply pipe supplying hydrogen sulfide to the heat treatment chamber;
a third supply pipe supplying acetylene to the heat treatment chamber; and
The nitriding heat treatment apparatus comprising a fourth supply pipe for supplying nitrogen to the heat treatment chamber.
According to claim 2,
The internal temperature of the heat treatment chamber is 470-590 ° C.
According to claim 2,
The internal temperature of the ammonia treatment unit is maintained at 800-900 ° C.
delete According to claim 1,
the combustion unit,
an outer housing connected to the sulfur removal unit;
an inner housing disposed inside the outer housing and into which the exhaust gas discharged from the sulfur removal unit flows; and
and a burner unit installed in the outer housing to burn exhaust gas discharged from the inner housing to the outer housing.
According to claim 7,
The burner part,
a burner body part disposed to surround an upper side of the outer housing; and
and a plurality of injection nozzles disposed on the burner body to inject fuel gas to the upper side of the outer housing.

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