JPS6116912B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a roller hearth type continuous gas carburizing furnace.

(Prior art) Conventional continuous gas carburizing furnaces are generally of the trapezia type, so as shown in Japanese Patent Publication No. 49-29055, each zone in the furnace is separated by a partition wall installed on the ceiling of the furnace. It is divided into temperature rising (heating) - carburizing - temperature cooling zones by a certain drop arch, and the material to be treated is placed on trays, and the trays are conveyed through the furnace in contact with each other so that they can be carburized as needed. It's summery.

(Problems to be Solved by the Invention) However, in the conventional continuous gas carburizing furnace, each zone is divided by drop arches, so atmosphere control in each zone is not sufficient, and the materials to be treated are not in contact with each other. Since the materials to be treated are placed on trays that are conveyed by a machine, the gaps between each material to be treated are small. Therefore, when heating (temperature raising), gradual heating is required, which not only lengthens the heating (temperature raising) time. A temperature difference tends to occur between the opposite side of the adjacent treated material and the side of the furnace side wall, making it impossible to perform uniform carburizing treatment.
Furthermore, when the temperature is lowered, there is a problem in that it takes a long time to uniformly lower the temperature to the quenching temperature due to the influence of radiant heat from the carburizing zone.

Therefore, in the present invention, technical improvements are made to improve the atmosphere controllability in each zone and to ensure uniform heating (temperature rise) and temperature cooling of the treated material to uniformly carburize the treated material. Take it as a challenge.

(Means for Solving the Problems) In order to solve the above technical problems, the present invention includes:
The means of transporting the material to be processed has been changed from the conventional tray pusher method to a roller hearth method, and the interior of the furnace is divided into a charging preparation chamber, a heating chamber, a carburizing chamber, and a temperature cooling and holding chamber by opening and closing doors, and the conveyance is driven independently into each chamber. A group of rollers is provided, and the group of conveying rollers in the carburizing chamber is composed of a group of loading section conveying rollers, a group of central conveying rollers, and a group of extracting section conveying rollers.

(Example) In the drawing, 1 indicates a charging door 2 and an extraction door 3 at the front and rear.
A roller hearth type continuous gas carburizing furnace equipped with
The inside of the furnace is divided into a charging preparation chamber 5, a heating chamber 6, a carburizing chamber 7, and a temperature-lowering holding chamber 8 by means of insulating opening/closing doors 4a, 4b, and 4c.
The chambers 5, 6, 7, and 8 are each equipped with a radiant tube burner 15 and a circulation fan 6.
are arranged to form an independent room.

The conveying roller groups in the carburizing chamber 7 include a charging section conveying roller group 7a and a central conveying roller group 7b to 7.
g, extraction section conveyance roller group 7h, loading section conveyance roller group 7a and extraction section conveyance roller group 7h
are connected to motors 12a and 12b with reduction gears, and the roller group 5a of the heating chamber 5, the roller group 7a of the carburizing chamber 7, and the roller group 8a of the temperature-lowering holding 8 are connected by electromagnetic clutches 15a to 15i. Each roller group can be rotated independently.

Further, the conveying roller groups 5a, 6a, 8a of the charging preparation chamber 5, heating chamber 6, temperature lowering and holding chamber 8 are connected to motors 10a, 10b, 10c with reducers and forward/reverse switching device 1.
It is connected to roller drive devices 9a, 9b, and 9c consisting of rollers 1a, 11b, and 11c, and is capable of forward and reverse rotation.

The loading preparation chamber 5, the heating chamber 6, and the temperature lowering/maintaining chamber 8 form a space in which a tray on which the material to be processed W is placed can reciprocate within a predetermined range.

13 is a known hardening device connected through the extraction door 3, and 14 is a charging table.

Next, the roller hearth type continuous gas carburizing furnace 1
Explain how the system operates.

The workpiece W placed on the tray is loaded from the loading table 14 into the loading preparation chamber 5, and is reciprocated within the loading preparation chamber 5 by forward and reverse rotation of the roller drive device 9a. Heating means 15 and circulation fan 1
6, while the inside of the charging preparation chamber 5 is purged with the furnace atmosphere gas from the heating chamber 6. After the purge in the charging preparation chamber 5 is completed, the preheated material W to be processed is opened by opening the opening/closing door 4a and the roller drive device 9.
Charging preparation chamber 5 due to high-speed normal rotation synchronized drive of a and 9b.
The material then moves to the heating chamber 6, and is heated (temperature raised) to approximately the carburizing temperature while reciprocating by "closing" the opening/closing door 4a and forward/reverse driving of the roller drive device 9b.
Meanwhile, the next material to be processed W is charged into the charging preparation chamber 5, and the material to be processed is preheated and the charging preparation chamber 5 is purged in the same manner as described above. After the temperature rises, the workpiece W in the heating chamber 6 is carburized by opening the opening/closing door 4b and driving the roller group 6a of the heating chamber 6 and the charging section roller group 7a of the carburizing chamber 7 in high-speed normal rotation synchronously. It moves to chamber 7 and is thereafter transported to the extraction side. In addition, the opening/closing door 4
The material to be processed W in the charging preparation chamber 5 is transferred to the heating chamber 6 by "closing" the opening/closing door 4a, "opening" the opening/closing door 4a, and driving the roller groups 5a and 5b in normal rotation in synchronized rotation.

Next, when the material to be processed W transferred to the carburizing chamber 7 leaves the loading section roller group 7a, the material in the heating chamber 6 is opened by opening the opening/closing door 4b and driving the transport roller groups 6a and 7a in high-speed normal rotation synchronously. The processing material W is transferred so as to be close to the preceding processing material W. Thereafter, by similar operations, the material to be processed W is transferred to the charging preparation chamber 5, the heating chamber 6,
It passes through the carburizing chamber 7 and is carburized.

In FIG. 1, when the first processed material W of the carburizing chamber 7 is positioned above the extractor roller group 7h of the carburizing chamber 7, the opening/closing door 4c is "opened" and the roller group 7h,
The material to be processed W is transferred to the temperature-lowering/holding chamber 8 by the high-speed forward rotation synchronized drive of the roller drive device 9c, and is moved back and forth by the forward/reverse rotation drive of the roller drive device 9c while being moved by the circulation fan 16.
The temperature is lowered to the quenching temperature. In addition, the material to be treated W
Once the temperature has moved to the temperature lowering and holding chamber 8, the heating chamber 5
The material to be treated W is transferred from the carburizing chamber 7 and the charging preparation chamber 5 to the heating chamber 6. After the temperature of the material to be processed W has decreased, the extraction door 3 is "opened" and the roller drive device 9c is driven in the forward direction to move it to the quenching chamber 13, and after the quenching process, it is extracted out of the furnace.

In the above embodiment, the charging preparation chamber 5 has a function of preheating the material W to be processed, but it is not necessarily necessary to have a preheating function, and in this case, the roller group 5a of the charging preparation chamber 5 is Not only is there no need for reverse rotation, there is also no need to provide heating means or a circulation fan. Further, the conveying roller groups 6a and 8a of the heating chamber 6 and the temperature-lowering/maintaining chamber 8 can be switched between high and low speeds, so that the processing in the chamber is carried out at a low speed, and the heating chamber 5 is transferred to the carburizing chamber 7 and the carburizing chamber 7 is transferred to the temperature-lowering/maintaining chamber 8. The processing material W may be transferred at high speed.

Furthermore, as shown in FIG. 2, a plurality of conveyance roller groups 6 are independently driven to correspond to the number of the workpieces W located in the heating chamber 6.
It may also be a ₁ or 6a ₂ .

(Effects of the Invention) As is clear from the above description, in the present invention, the conveying means of the continuous gas carburizing furnace is a roller hearth type, and the carburizing furnace is connected to the charging preparation chamber, the heating chamber, and the carburizing chamber through opening/closing doors. It consists of a chamber and a temperature-lowering/maintaining chamber, and each chamber is equipped with a group of independently driven conveyor rollers.
In addition, since the conveyance roller group in the carburizing chamber is divided into a loading section conveyance roller group, a central section conveyance roller group, and an extraction section conveyance roller group, it is possible to accurately and easily control the atmosphere in each zone, and also to Heating (temperature raising) of the material to be treated W in the chamber and cooling of the material to be treated in the temperature lowering and holding chamber can be performed with a large interval between the materials to be treated, and the interval between the materials to be treated in the carburizing chamber can be made small. , therefore when heated,
The object to be treated is heated uniformly, and uneven carburization does not occur.
When the temperature is lowered, the temperature is uniformly lowered so that uneven quenching does not occur, and the heating and temperature lowering treatments can be performed in a short time, making it possible to shorten the furnace length.

Furthermore, if the conveyance roller groups in the heating chamber and the temperature-lowering/maintaining chamber can be rotated in forward and reverse directions, the residence time in the chamber can be ensured without increasing the length of the chamber, and the length of the furnace can be further shortened.

Furthermore, if the central transport roller group of the carburizing chamber is composed of a plurality of roller groups, the empty zone in the furnace can be reduced when carburizing conditions are changed, and efficient switching operations can be performed.

In addition, if a heating means is installed in the charging preparation chamber and the material to be treated is preheated while the chamber is being purged, the room can be purged with gas expanded by heating, which can reduce the amount of purge gas. Not only is the heating (temperature raising) time for the treated material further shortened, but also impurities such as oil adhering to the treated material can be vaporized and removed at the same time.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of a roller hearth type continuous gas carburizing furnace according to the present invention, and FIG. 2 is a schematic sectional view showing a modification of the heating chamber. 4...Opening/closing door, 5...Charging preparation room, 5a...Charging preparation room roller group, 6...Heating chamber, 7...Carburizing chamber, 8...Temperature lowering/maintenance chamber, 6a...Heating chamber roller group , 7a... Loading section roller group, 7b to 7g... Center roller group, 7h... Extraction section roller group, 8a...
... Temperature lowering and holding chamber roller group, W... Material to be treated.

Claims (1)

[Claims] 1. A continuous gas carburizing furnace with a charging preparation chamber,
The carburizing chamber is divided into a heating chamber, a carburizing chamber, and a temperature-lowering/maintenance chamber, and each chamber is provided with a group of independently driven conveying rollers. A roller hearth type continuous gas carburizing furnace characterized by an extraction section divided into a group of conveyor rollers. 2. The roller hearth according to claim 1, wherein among the charging preparation chamber, the heating chamber, the carburizing chamber, and the temperature-lowering/holding chamber, at least the conveying roller group in the heating chamber and the temperature-lowering/holding chamber is a conveying roller group capable of forward and reverse rotation. Type continuous gas carburizing furnace. 3. A roller hearth-type continuous gas carburizing furnace according to claim 1 or 2, wherein the central conveying roller group of the carburizing chamber comprises a complicatedly divided conveying roller group.