JP3005914B2 - Atmospheric heat treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atmosphere heat treatment such as a gas carburizing treatment and a gas nitrocarburizing treatment, and more particularly to an atmosphere heat treatment apparatus capable of performing both a gas carburizing treatment and a gas nitrocarburizing treatment.

[0002]

2. Description of the Related Art Heretofore, gear transmissions of automobiles have been subjected to a large amount of gas carburizing in a continuous gas carburizing furnace, and crankshafts and the like have been subjected to a large amount of gas nitrocarburizing treatment in a continuous gas nitrocarburizing furnace. In the continuous furnace type furnace, there are differences between the gas carburizing process and the gas nitrocarburizing process, such as the heating capacity due to the processing temperature difference, the stirring speed of the atmosphere gas, and the need for a cooling zone only during the carburizing process. The structure of the furnace is dedicated to the processing.

[0003]

However, in the case where the number of gas carburized products decreases due to demand and the number of gas nitrocarburized products increases, and the carburizing continuous furnace becomes inoperable, the production schedule is reduced. It is necessary to change the continuous furnace from gas carburizing to gas nitrocarburizing according to
/ S for the gas stirrer that generated the atmospheric gas flow rate of 18.0 to 15.0 m / s for the gas nitrocarburizing process, piping work accompanying the change of the atmospheric gas, And the need to reload fire-resistant and heat-insulating bricks, etc., which has not been implemented in terms of capital investment efficiency or production efficiency.

Accordingly, the present invention provides an atmosphere heat treatment apparatus which combines gas carburizing treatment and gas nitrocarburizing treatment in the same continuous furnace and is configured to easily change the treatment conditions, thereby solving the above-mentioned problems. It is intended to do so.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a furnace for both gas carburizing and gas nitrocarburizing, wherein an enriched gas and a modified gas are converted during the gas carburizing process. An atmosphere gas supply unit for supplying an ammonia gas and a modified gas to the furnace during the gas nitrocarburizing treatment while supplying the gas into the furnace, a stirrer for stirring the gas supplied by the atmosphere gas supply unit, A stirrer shift control unit that controls the speed of the stirrer so that the gas supplied by the gas supply unit has a flow rate corresponding to the gas carburizing process or the gas nitrocarburizing process. The gas nitrocarburizing process or the gas nitrocarburizing process can be changed to a gas carburizing process.

[0006]

According to the above arrangement, during the gas carburizing process, the enriched gas and the modified gas are supplied into the furnace by the atmosphere gas supply means, and the speed of the stirrer is controlled by the stirrer speed change control means. At a flow rate corresponding to the gas carburizing treatment, and the surface of the object to be treated in the furnace is subjected to the gas carburizing treatment.

During the gas nitrocarburizing process, the ammonia gas and the modified gas are supplied into the furnace by the atmospheric gas supply means, and the shift of the stirrer is controlled by the stirrer shift control means. The surface of the object to be treated in the furnace is subjected to a gas soft nitriding treatment at a flow rate corresponding to the soft nitriding treatment.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. The continuous furnace 1 has a door 2 on the entrance side and a door 3 on the exit side, as shown in FIG. A front chamber 5 is provided in front of the door 2, and a cooling chamber 6 is provided behind the door 3. A supply port 7 is provided on one of the left and right sides of the front chamber 5, and has a carry-in door. A pusher 9 is mounted in front of the front room 5. This pusher 9
Rod 9a is slidable in the front-rear direction.
Is placed in the front chamber 5 through the supply port 7 and pushed backward by the pusher rod 9a.
It is configured to be charged into the continuous furnace from the entrance door 2. A rail is horizontally provided in the lower part of the continuous furnace in the moving direction of the work W, and the tray 10 on which the work W is placed flows on the rail continuously in one direction (not shown).

On the ceiling of the continuous furnace 1, partition walls 12, 12, 12 of a predetermined length are suspended, and the first chamber is partitioned by the partition walls 12, 12, 12 in order from the entrance side. 1a, 2nd room 1b, 3rd room 1c, and 4th room 1d
Are connected linearly. This first room 1a is the second room 1
b, the third chamber 1c and the fourth chamber 1d are set to be longer in the workpiece flowing direction. The stirrers 13a and 13a are arranged in the upper part of each of these chambers in order from the inlet side.
b, 13c and 13d are rotatably supported. These stirrers 13a, 13b, 13c, and 13d are based on a stirrer for a gas nitrocarburizing furnace, and perform variable frequency control (inverter control) by connecting a drive motor of the stirrer to an AC and variable frequency power supply. Variable speed control is performed by changing the number, and a low gas flow rate of 4.5 m / s is generated by setting to about 15 Hz during carburizing, and. The frequency is changed from 60 HZ to 50 HZ to generate a high gas flow velocity of 18.0 m / s to 15 m / s.

By the way, the stirrers 13a, 13b, 13
In steps c and 13d, the atmosphere gas is stirred in the continuous furnace, a predetermined gas stirring flow rate is generated, and the workpiece W is uniformly contacted with the atmosphere gas. In the case of the gas nitrocarburizing treatment, it is necessary to always supply fresh atmospheric gas to the surface of the work W, and it is necessary to increase the gas stirring flow rate by the amount of obtaining atomic nitrogen.

Further, heaters (not shown) for generating a high temperature required for heat treatment are provided on the side surfaces and lower portions of the chambers 1a, 1b, 1c, 1d. In the case of carburizing,
The first chamber 1a is a preheating zone, the second chamber 1b is a carburizing zone, the third chamber 1c is a cooling zone, the fourth chamber 1d is a quench holding zone, and in the case of nitrocarburizing, the first chamber 1a is preheated. The zone, the second chamber 1b, the third chamber 1c, and the fourth chamber 1d are configured to be heat equalizing zones.

An elevator 15 is provided above the cooling chamber 6.
The mounting table 16 is suspended from the elevator 15 so as to be able to move up and down. An oil tank 17 is provided below the cooling chamber 6, and the work W on the mounting table 16 can be immersed in the oil tank 17 by lowering the mounting table 16. Further, an outlet door 19 is provided above the rear side of the cooling chamber 6.

Next, the atmosphere gas supply means will be described. As the atmosphere gas, three types of enriched gas composed of gases such as C ₃ H ₈ and C ₄ H ₁₀ , ammonia gas and modified gas are used in order to perform gas carburizing treatment or gas nitrocarburizing treatment. In this case, the modified gas and the enriched gas are measured, and in the case of the gas nitrocarburizing treatment, the modified gas and the ammonia gas are measured by the flow meter R in an appropriate amount according to each treatment and supplied to the continuous furnace 1 by a predetermined amount. .

The enriched gas is supplied from the tank to the pipe 2
1. Ammonia gas is connected to a flow meter R1 via a valve V12,
The flow is branched into pipes 23 and 24 through the pipes 2, and flow meters R2 and R5 are connected to the pipes 23 and 24 via valves V13 and V16, respectively. Further, the shift gas is branched from the shift furnace through a pipe 26 to pipes 27 and 28, and the pipe 28 is branched to pipes 29 and 30. Further, the pipes 27, 29, and 30 respectively have a valve V14. , V15 and V17 through the flow meter R3
R4 and R6 are connected. Therefore, the flow meter R1
Is configured to measure and supply enriched gas, the flow meters R2 and R5 to measure ammonia gas, and the flow meters R3, R4 and R6 to measure and supply modified gas.

The flow meters R2, R3, R4 are connected to valves V1, V3 through pipes 31, 32, 33, respectively.
2 and V3 are connected, and a valve V4 is connected to the flow meter R5 via a valve V19 and a pipe. A pipe 36 is connected to the flow meter R <b> 1, and the pipe 36 is connected to the pipe 33. A pipe 37 is connected to the flow meter R6 via a valve V18, and the pipe 37 is connected to the pipe.

A valve V5 is connected to the valve V2 via a pipe 39, a valve V1 is connected to a pipe 39 via a pipe 40, and an outlet pipe of the valve V5 is connected to the first pipe. It is open near the chamber agitator 13a. A pipe 41 is connected to the valve V3,
The pipe 41 is branched into pipes 42, 43, and 44. Further, valves V7, V8, V9 are connected to these pipes 42, 43, 44, respectively.
7, V8 and V9 outlet pipes are respectively connected to the stirrer 13
Opened near b, 13c, 13d. A valve V1 is provided between the pipes 42 and 43 of the pipe 41.
0 is provided.

A pipe 45 is connected to the valve V4, and a pipe 46 is branched from the pipe 45. The pipe 45 is connected to the pipe 43 via a valve V11, and the pipe 46 is connected to the pipe 41 via a valve V6.

FIG. 2 is a view showing a heater relationship of the continuous furnace 1. Electric heating tubes Ha-1 are provided on both left and right sides of the first chamber 1a.
To H-5, and electric heating tubes Hav-1 to Hav-4 are horizontally provided on the floor side of the first chamber 1a. Hb-1 to Hb-3, Hc-1 to Hc-3, and Hd-1 to Hd-3 are respectively suspended on the left and right sides of the second chamber 1b, the third chamber 1c, and the fourth chamber 1d. An electric heating tube Hdv-1 is horizontally provided near the floor side exit of the four chambers 1d. The electric heating tubes are grouped into the first, second, third, and fourth chambers, and are connected to four transformers Ta, Tb, Tc, and Td, respectively. These transformers Ta, Tb, Tc, Td are magnet switches or heater breakers SWa, SWb, SWc, SW, respectively.
The power supply E is connected via d. Magnet switches SWa, SWb, SWc, SWd according to each processing condition
Is turned ON or OFF, and the processing temperature is controlled by the energization time.

Next, the operation of the above-described atmosphere heat treatment apparatus of the present invention will be described. When performing the gas carburizing process using the continuous furnace 1, the second chamber carburizing zone 1b is set at a processing temperature of 920 to 880 ° C., and the first and third chambers 1a, 3c, and 4d before and after the carburizing zone 1b. Set lower. At this time, since the third chamber 1c, which is the temperature lowering zone, is not heated, the magnet switch SWc is turned off. Cycle time is 40-30 minutes, total carburized layer depth is 0.9-0.6m
m, the atmosphere gas is a shift gas and an enriched gas. The speed of the stirrers 13a, 13b, 13c, 13d is set so as to generate a gas flow velocity of about 4.5 m / s at low speed by variable frequency control or variable speed control.

The transformed gas is supplied to flow meters R3, R4, R6
Is supplied to the first chamber 1a, the second chamber 1b, the third chamber 1c, and the fourth chamber 1d via the pipes 32, 33, 37, and 34, and the enriched gas is adjusted to an appropriate amount by the flow meter R1. Measured and carburized via pipes 36 and 33
The gas is sent to the chamber 1b, and the atmosphere gas necessary and sufficient for the gas carburizing treatment is supplied. On the other hand, the ammonia gas is supplied to the valve V1.
3. By closing V16, it is not supplied to each chamber of the continuous furnace 1. Further, the work W placed on the tray 10 is supplied from the supply port 7 to the front chamber 5, and the work W
It is pushed backward by a and is continuously charged into the continuous furnace from the entrance door 2. The work W placed on the tray 10 on the lower rail in the continuous furnace continuously flows in one direction, and the first chamber 1a, the second chamber 1b, the third chamber 1c, and the fourth chamber
The workpiece W passes through the chamber 1d in this order, and the workpiece W is subjected to each heat treatment and subjected to a surface treatment. The workpiece W is transferred from the door 3 to the cooling chamber 6 and moves onto the mounting table 16. The work W moved onto the mounting table 16 is lowered by the elevator 15 and
After being immersed in the cooling device and being cooled, it is lifted by the elevator 15 and is carried backward from the exit door 19.

Next, when performing the gas nitrocarburizing treatment using the continuous furnace 1, the first chamber 1a becomes a preheating zone, and the second chamber 1b, the third chamber 1c, and the fourth chamber 1d become the soaking zones. Become. Atmosphere gases are ammonia gas and modified gas.
The speeds of 3a, 13b, 13c, and 13d are about 18.0 to 15.0 m / m at high speed by variable frequency control or variable speed control.
s is set to generate the gas flow velocity.

Ammonia gas is measured to an appropriate amount by a flow meter R2, supplied to the first chamber 1a via a pipe 31, and is also metered to an appropriate amount by a flow meter R5. The valve V19, the pipe 34, the valves V4, V6 , Piping 41, 42, 43, 4
The air is supplied to the second chamber 1b, the third chamber 1c, and the fourth chamber 1d via the line 4. At the same time, the metamorphic gas is measured to an appropriate amount by the flow meter R3 and supplied to the first chamber 1a via the pipe 32, and is also metered to an appropriate amount by the flow meter R4, and the pipes 33, 41, 42, 4
The liquid is supplied to the second chamber 1b, the third chamber 1C, and the fourth chamber 1d through 3, 44. Therefore, an atmosphere gas necessary and sufficient for the gas nitrocarburizing treatment is supplied. On the other hand, the enriched gas is not supplied to each chamber of the continuous furnace 1 by closing the valve V12.

The work W placed on the tray 10
Are continuously charged into the continuous furnace as in the case of the gas carburizing treatment, and the first chamber 1a, the second chamber 1b, the third chamber 1c, the fourth chamber
The workpiece W passes through the chamber 1d in this order. During this time, the workpiece W is subjected to each heat treatment, surface-treated, cooled in the cooling chamber 6, and then carried out from the exit door 19 to the rear.

The supply of the atmosphere gas can be easily carried out from the gas carburizing treatment to the gas nitrocarburizing treatment by opening and closing the valves V1 to V19 and by adjusting the flow rate of the flow meters R1 to R6. It can be changed to gas carburizing. Details of the opening and closing of valves V1 to V19 during gas carburizing and gas nitrocarburizing are shown in FIG.
Is shown in

The stirrers 13a, 13b, 13c, 1
Since the variable frequency control (inverter control) or the variable speed control is performed for 3d, the gas flow rate is set to 1 from the low gas flow rate of 4.5 m / s.
It can be easily changed to a high gas velocity of 8.0-15.0 m / s or vice versa.

[0026]

As described above, according to the present invention,
Using the same furnace, from gas carburizing to gas nitrocarburizing,
Alternatively, when changing the reverse, the atmosphere gas can be supplied by the atmosphere gas supply means and the stirrer can be shifted by the agitator shift control means so as to have a gas flow rate corresponding to the processing. It can be easily changed to gas carburizing treatment or gas nitrocarburizing treatment.

When changing the same furnace from gas carburizing to gas nitrocarburizing or vice versa,
Remodeling work of the stirrer and piping system, which were necessary in the past, can be omitted, and the cost of the remodeling work can be reduced.
It is possible to easily change to gas carburizing or gas nitrocarburizing according to the production plan, reduce the number of idle furnaces, effectively use equipment, and improve production efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an atmosphere heat treatment apparatus according to the present invention.

FIG. 2 is a diagram showing a heater relationship in a continuous furnace according to the present invention.

FIG. 3 is a diagram showing opening and closing of a valve according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Continuous furnace 1a 1st chamber 1b 2nd chamber 1c 3rd chamber 1d 4th chamber 13a, 13b, 13c, 13d Stirrer R Flow meter V Valve W Work

Claims (1)

(57) [Claims] A furnace for both gas carburizing and gas nitrocarburizing, wherein an enriched gas and a modified gas are supplied into the furnace during the gas carburizing and an ammonia gas and a modified gas are supplied to the furnace during the gas nitrocarburizing. Atmosphere gas supply means for supplying the gas into the furnace, a stirrer for stirring the gas supplied by the atmosphere gas supply means, and gas supplied by the atmosphere gas supply means, wherein the gas carburizing treatment or the gas nitrocarburizing treatment is performed. And a stirrer speed change control means for controlling the speed of the stirrer so as to have a flow rate corresponding to the flow rate of the gas. Atmospheric heat treatment apparatus characterized by the above-mentioned.