A gas carburizing furnace for heat treatment of metal surfaces

Abstract

The utility model discloses a kind of gas carburizing furnace for metal surface heat treatment belong to carburizing furnace technical field, including furnace shell, furnace lining, heat-insulating door, carburizing chamber, quenching chamber, carburizing system, combustion system, circulating fan;The heat-insulating door is divided into carburizing chamber and quenching chamber along transverse to furnace body, two chambers can be parallel independent operation;The carburizing system is equipped with metering pump and high-speed pulse solenoid valve, the carburizing chamber and quenching chamber top are equipped with waste gas return pipe, the waste gas return pipe is connected with combustion system, arc flow guide fin is welded in carburizing chamber inner wall along axial equidistant, top circulating fan drive furnace gas is along the flow guide fin 360 ° annular backflow is formed;Filter plate is arranged between the carburizing chamber and circulating fan, and can be pulled out and inserted.This application arc flow guide fin and top circulating fan cooperate, make furnace gas form continuous annular backflow around workpiece, eliminate airflow dead angle, temperature distribution and carbon potential distribution are more uniform, and better consistency of carburized layer quality.

Description

Technical Field

[0001] This utility model belongs to the field of carburizing furnace technology, specifically relating to a gas carburizing furnace for metal surface heat treatment. Background Technology

[0002] Traditional gas carburizing furnaces generally have the following drawbacks: The short furnace gas circulation path and numerous dead zones in the carburizing chamber result in poor carbon potential uniformity and large fluctuations in the carburizing layer depth. Carbon black continuously deposits with the circulating furnace gas, clogging the heating element and fan, requiring furnace shutdown for cleaning, resulting in low effective operating rate. Direct emission or simple combustion of exhaust gas wastes heat and causes CO / NOx exceedances. The quenching cooling method is singular and cannot achieve online switching between fast and slow cooling based on the differences in material hardenability. Summary of the Invention

[0003] To address the aforementioned problems, this utility model discloses a gas carburizing furnace for heat treatment of metal surfaces.

[0004] To achieve the above objectives, the specific technical solution of this application is as follows: A gas carburizing furnace for metal surface heat treatment includes a furnace shell, a furnace lining, an insulation door, a carburizing chamber, a quenching chamber, a carburizing system, a combustion system, and a circulating fan; The insulation door divides the furnace body laterally into a carburizing chamber and a quenching chamber, which can operate independently in parallel. The carburizing system is equipped with a metering pump and a high-speed pulse solenoid valve. Both the top of the carburizing chamber and the quenching chamber are equipped with exhaust gas return pipes, which are connected to the combustion system. The inner wall of the carburizing chamber is welded with arc-shaped guide fins at equal intervals along the axial direction. The top circulating fan drives the furnace gas to form a 360° annular return along the guide fins. A removable filter plate is provided between the carburizing chamber and the circulating fan to capture carbon black particles. The filter plate is movable.

[0005] Based on the above technical features, preferably, the inlet of the exhaust gas return pipe is located at the top of the carburizing chamber and the top of the quenching chamber, and the outlet is connected to the combustion system. The exhaust gas return pipe is equipped with an electric regulating valve, which is continuously adjustable.

[0006] Based on the above technical features, preferably, the filter plate is a SiC foam ceramic filter plate, which is installed on a pull-out guide rail and is driven by a cylinder to move on the pull-out guide rail.

[0007] Based on the above technical features, furthermore, a cyclone venturi dust collector is connected upstream of the filter plate.

[0008] Based on the above technical features, furthermore, a laser transmittance monitor is provided downstream of the filter plate. The laser transmittance signal is connected to the cyclone venturi dust collector and the carbon potential controller. For every 1% decrease in transmittance, the carbon potential set value is automatically lowered by 0.02%C, forming a "carbon black prevention-carbon potential control" double closed loop. There are no network carbides on the surface during supersaturated carburizing.

[0009] Based on the above technical features, preferably, the insulation door is a double-layer shell with circulating water in the middle to ensure that the high temperature of the carburizing chamber is not disturbed by the cold air of the quenching chamber, and also to prevent the gate valve from deforming and jamming.

[0010] Based on the above technical features, preferably, the top of the quenching chamber is provided with a 2-12 bar steplessly adjustable high-pressure nitrogen nozzle ring, which can be selected for fast or slow cooling for different materials.

[0011] Compared with the prior art, the beneficial effects of this application are as follows: In this application, the carburizing chamber and the quenching chamber are independent of each other, and heating carburizing and cooling quenching can be carried out simultaneously. The production cycle is no longer mutually restricted, which significantly improves equipment utilization and production efficiency. The arc-shaped guide fins work in conjunction with the top circulating fan to create a continuous annular reflux of furnace gas around the workpiece, eliminating dead airflow angles, resulting in more uniform temperature and carbon potential distribution, and better consistency in diffusion layer quality. The movable filter plate traps carbon black particles in the furnace gas at any time. Combined with the cyclone venturi pre-dust removal, it reduces the deposition of carbon black in the furnace, extends the continuous operation cycle, and reduces the frequency of shutdown cleaning. The system links laser transmittance monitoring with carbon potential control. Once the filter plate shows signs of clogging, the system automatically lowers the carbon potential to suppress carbon black formation, achieving a synergistic effect of "anti-carbon black and carbon potential control" and effectively avoiding defects such as surface network carbides. The exhaust gas from the top of the carburizing chamber and quenching chamber is introduced into the combustion system through a return pipe, which decomposes harmful gases, recovers waste heat, reduces energy waste, and lowers emissions. The double-layer shell is circulated with cooling water to prevent the high temperature in the carburizing chamber from being transferred to the quenching chamber, thus preventing the insulation door from deforming and jamming due to heat, maintaining reliable sealing, and reducing maintenance workload. The high-pressure nitrogen nozzle at the top of the quenching chamber can continuously adjust the pressure within a wide range to achieve fast or slow cooling, meeting the cooling speed requirements of different materials and processes, and expanding the applicability of the equipment. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of a gas carburizing furnace for metal surface heat treatment according to the present invention; Figure 2 This is a schematic diagram of air circulation. List of identifiers in attached diagrams: 1. Furnace shell; 2. Furnace lining; 3. Insulation door; 4. Carburizing chamber; 5. Quenching chamber; 6. Carburizing system; 7. Combustion system; 8. Circulating fan; 9. Waste gas return pipe; 10. Filter plate. Detailed Implementation

[0013] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0014] It should be noted that the terms "upper," "lower," "left," "right," "front," and "rear" used in the following description refer to the directions shown in the accompanying drawings, while the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. Furthermore, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0015] like Figure 1 As shown, a gas carburizing furnace for metal surface heat treatment includes a furnace shell 1, a furnace lining 2, an insulating door 3, a carburizing chamber 4, a quenching chamber 5, a carburizing system 6, a combustion system 7, and a circulating fan 8; a sliding feeding platform is provided inside the furnace shell.

[0016] The insulating door 3 divides the furnace body laterally into a carburizing chamber 4 and a quenching chamber 5, and the two chambers can operate independently in parallel. The carburizing system 6 is equipped with a metering pump and a high-speed pulse solenoid valve. Both the top of the carburizing chamber and the quenching chamber are equipped with exhaust gas return pipes 9, which are connected to the combustion system 7. The inner wall of the carburizing chamber is welded with arc-shaped guide fins at equal intervals along the axial direction. The top circulating fan drives the furnace gas to form a 360° annular return along the guide fins. A removable filter plate 10 is provided between the carburizing chamber 4 and the circulating fan 8 for collecting carbon black particles. The filter plate is movable.

[0017] The inlet of the exhaust gas return pipe 9 is located at the top of the carburizing chamber 4 and the top of the quenching chamber 5, and the outlet is connected to the combustion system 7. The exhaust gas return pipe 9 is equipped with an electric regulating valve, which is continuously adjustable.

[0018] Preferably, the filter plate is a SiC foam ceramic filter plate, which is installed on a pull-out guide rail and is driven by a cylinder to move on the pull-out guide rail.

[0019] Preferably, the upstream of the filter 10 is connected to a cyclone venturi dust collector.

[0020] A laser transmittance monitor is provided downstream of the filter plate 10. The laser transmittance signal is connected to the cyclone venturi dust collector and the carbon potential controller. For every 1% decrease in transmittance, the carbon potential set value is automatically reduced by 0.02%C, forming a "carbon black prevention-carbon potential control" double closed loop. There are no network carbides on the surface during supersaturated carburizing.

[0021] Preferably, the insulating door 3 has a double-layer shell with circulating water in the middle to ensure that the high temperature of the carburizing chamber is not interfered with by the cold air of the quenching chamber, and also to prevent the gate valve from deforming and jamming.

[0022] Preferably, the top of the quenching chamber 5 is equipped with a 2–12 bar steplessly adjustable high-pressure nitrogen nozzle ring, which can be selected for fast or slow cooling for different materials. Example

[0023] The carburizing system 6 includes a metering pump, a German HNP miniature magnetic coupling gear pump, which is infinitely adjustable from 0 to 30 mL / min; a high-speed pulse solenoid valve with a response time of 8 ms and a minimum single pulse of 0.05 mL, which can realize "pulse-diffusion" carburizing with a carbon potential control accuracy of ±0.02%C.

[0024] The exhaust gas return pipe 9 has its inlet located at the top of the carburizing chamber 4 and its outlet connected to the combustion system 7. The combustion system uses an Italian ESA self-preheating burner, and the electric regulating valve is driven by a BERGER Lahr stepper motor, which keeps the exhaust gas at a temperature above 950 ℃ for 0.5s in the burner, with a CO combustion rate of >99%.

[0025] The circulating fan uses a high-temperature centrifugal fan, and the furnace gas forms a 360° annular recirculation under the guidance of the guide fins, such as... Figure 2 As shown, the heat transfer coefficient of the workpiece surface is improved.

[0026] The laser transmittance monitor uses a 650 nm laser diode as the transmitter and a silicon photodiode as the receiver, with the signal connected to a PLC. The PLC's internal program is set to automatically lower the carbon potential setpoint by 0.02%C for every 1% decrease in transmittance; when the transmittance is <70%, cylinder 12 is automatically activated to pull out the filter plate 10, triggering an audible and visual alarm to prompt manual cleaning.

[0027] The top of quenching chamber 5 is equipped with 12 high-pressure nitrogen nozzles arranged in a double ring. For different materials, the "rapid cooling" or "slow cooling" formula can be selected on the HMI. It should be noted that the accompanying drawings merely illustrate the technical concept of the present invention and should not be used to limit the scope of protection of the present invention. For those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A gas carburizing furnace for metal surface heat treatment, characterized in that: The furnace includes a furnace shell, furnace lining, insulation door, carburizing chamber, quenching chamber, carburizing system, combustion system, and circulating fan. The insulation door divides the furnace body laterally into a carburizing chamber and a quenching chamber, which can operate independently in parallel. The carburizing system is equipped with a metering pump and a high-speed pulse solenoid valve. Both the top of the carburizing chamber and the quenching chamber are equipped with exhaust gas return pipes, which are connected to the combustion system. The inner wall of the carburizing chamber is welded with arc-shaped guide fins at equal intervals along the axial direction. The top circulating fan drives the furnace gas to form a 360° annular return flow along the guide fins. A removable filter plate is provided between the carburizing chamber and the circulating fan to capture carbon black particles. The filter plate is movable.

2. The gas carburizing furnace for metal surface heat treatment according to claim 1, characterized in that: The inlet of the exhaust gas return pipe is located at the top of the carburizing chamber and the top of the quenching chamber, and the outlet is connected to the combustion system. The exhaust gas return pipe is equipped with an electric regulating valve, which is continuously adjustable.

3. The gas carburizing furnace for metal surface heat treatment according to claim 1, characterized in that: The filter plate is a SiC foam ceramic filter plate, which is installed on a pull-out guide rail and is driven by a cylinder to move on the pull-out guide rail.

4. The gas carburizing furnace for metal surface heat treatment according to claim 1, characterized in that: The filter plate is connected to a cyclone venturi dust collector upstream.

5. A gas carburizing furnace for metal surface heat treatment according to claim 1, characterized in that: A laser transmittance monitor is installed downstream of the filter plate, and the laser transmittance signal is connected to the cyclone venturi dust collector and the carbon potential controller.

6. The gas carburizing furnace for metal surface heat treatment according to claim 1, characterized in that: The insulated door has a double-layer shell with circulating water flowing through the middle.

7. A gas carburizing furnace for metal surface heat treatment according to claim 1, characterized in that: The top of the quenching chamber is equipped with a 2–12 bar stepless adjustable high-pressure nitrogen nozzle ring.

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