JP2002146512A - Continuous vacuum carburizing method and its furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous vacuum carburizing method and its device in which flexibility is increased by efficiently dealing with change in the cycle time of an object to be processed and in the depth of carburization, in such continuous vacuum carburizing furnace for ferro-alloys that includes chambers for charging, heating-up, carburizing, diffusing, cooling-down/holding and quenching. SOLUTION: The continuous vacuum carburizing furnace 1 is composed of a charging chamber 18 and such independent chambers as a heating-up chamber 11 and plural carburizing/diffusing chambers 12a, 12b, 12c that are each partitioned by vacuum sealing doors. The furnace carries out carburization and diffusion, and it is also designed to perform a function of the heating-up chamber in the carburizing/diffusing chamber by adding a temperature raising function to at least one of the carburizing/diffusing chambers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for continuous vacuum carburizing of iron alloy parts including a charging chamber, a carburizing chamber, a diffusion chamber, a cooling chamber and a quenching chamber.

[0002]

2. Description of the Related Art A conventional continuous vacuum carburizing furnace for batch-feeding iron alloy parts is disclosed in, for example, June 1998 ADVANNCED METALS.
& PROCESSES Magazine F Preisser etc. "UPDATE ONVACUUM-B
A continuous vacuum carburizing furnace as shown in Fig. 3 described in Fig. 5 of ASED CARBURIZINNG "is known. This continuous vacuum carburizing furnace is an independent carburizing chamber separated by a vacuum seal door following a heating chamber. After being carburized in vacuum, it was subjected to diffusion treatment in an independent diffusion chamber separated by a vacuum seal.The vacuum carburization method strictly controls the carburization time (T _C ) and the diffusion time (T _d ) and This is a treatment method in which the time ratio (T _C / T _d ) must be changed according to the carburizing temperature, for example, when the treatment temperature is changed from 930 ° C. to 1040 ° C., the ratio (Tc / Td) becomes 1.5 In order to obtain the same carburization depth, carburization can be performed in a shorter time as the treatment temperature is higher. Choosing a lower processing temperature makes it easier to control the depth Also, depending on the material to be carburized, high-temperature carburizing may not be possible due to problems such as coarsening of the grains, etc. As described above, even though it is a continuous vacuum carburizing furnace, the processing temperature is set according to the required carburizing depth and material. Therefore, when carburized products are sent at regular intervals, such as in a continuous vacuum carburizing furnace, the cycle time is determined by the carburizing depth to be obtained.

[0003] Further, the temperature of the treated product is raised to the carburizing temperature by the heating time, that is, the stay time in the warming room, but if the cycle time is short, the treated product may not reach the predetermined temperature within the stay time in the warming room. . Generally, when the cycle time is short, the carburization depth is generally shallow,
The temperature rise time is a factor that determines the cycle time from diffusion. When the carburizing depth to be obtained is deep, the heating time does not matter, and the carburizing / diffusion time determines the cycle time.

[0004] The configuration of the continuous vacuum carburizing furnace covering the case where the carburizing depth is short and the cycle time is short to the case where the carburizing depth is deep and the cycle time is long is such that the treated product reaches a predetermined temperature when the cycle time is short. It is necessary to provide a heating chamber, a carburizing chamber for a long cycle time, and a diffusion chamber.

[0005]

However, if the treated product is constant, the carburizing treatment can be performed with the necessary and minimum equipment for exclusive use. However, equipment having flexibility, that is, equipment capable of performing a wide range of carburizing treatment conditions can be used. When considered, a heating chamber, a carburizing chamber, and a diffusion chamber having a capacity and number satisfying the assumed conditions are required.

An object of the present invention is to provide a continuous vacuum carburizing furnace for an iron alloy including a charging chamber, a heating chamber, a carburizing chamber, a diffusion chamber, a cooling / holding chamber, and a quenching chamber. It is an object of the present invention to provide a continuous vacuum carburizing method and apparatus capable of efficiently responding to changes and increasing flexibility.

[0007]

According to the present invention, a plurality of carburizing chambers are provided in a continuous vacuum carburizing furnace for iron alloy parts including a charging chamber, a heating chamber, a carburizing chamber, a diffusion chamber, a cooling / holding chamber, and a quenching chamber. Wherein each of the carburizing chambers is a carburizing and diffusing chamber that also serves as a diffusion chamber, performs carburizing and diffusion, and adds a temperature increasing function to at least one of the carburizing and diffusing chambers. The problems of the prior art described above have been solved by providing a continuous vacuum carburizing method and a continuous vacuum carburizing furnace characterized by functioning as a heating chamber.

[0008]

According to the present invention, the present invention provides a continuous vacuum carburizing furnace having a plurality of carburizing / diffusion chambers which are sequentially supplied at regular time intervals, and performs carburizing and diffusion of a treated product in a plurality of chambers. In addition, by adding a heating function to at least one of the plurality of carburizing / diffusion chambers and adding the function of the heating chamber to the carburizing / diffusion chamber as well, the treated product which could not be sufficiently heated in the heating chamber is subjected to the next carburizing / diffusion chamber. Provide a continuous vacuum carburizing method and device that increases the flexibility by increasing the temperature in the diffusion chamber and effectively using the carburizing and diffusion chamber to satisfy the required cycle time and required carburizing depth with the minimum equipment. It became something to do.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic elevational cross-sectional block diagram showing a plurality of carburizing / diffusion chambers serving as a carburizing chamber and a diffusion chamber according to an embodiment of the present invention applied to a continuous vacuum carburizing furnace for iron alloy parts. Is shown. In the present embodiment, the unloading room is provided with an example of a short cycle time, but depending on the cycle time,
It is not necessary to prepare. Continuous vacuum carburizing furnace 1 of the present embodiment
A heating chamber 11, three (or any other number) carburizing and diffusion chambers 12a, 12b and 12c, each separated by a vacuum sealing door, and a cooling / holding chamber 19 and an adjacent quenching chamber 15 and an unloading chamber 17. The tray or the basket 13 of the iron alloy component as the processed product is moved from left to right as viewed in the drawing by an internal feeder such as a walking beam or a roller (not shown).
In the present embodiment, one by one is continuously inserted from the charging chamber 18 into the heating chamber 11. The heating chamber 11 is designed to accommodate three trays or baskets 13 and is charged into the adjacent carburizing and diffusion chamber 12a in three cycles.
One tray or basket is loaded into each adjacent room, quenched in the quenching chamber 15, sent to the carry-out chamber 17, and taken out of the carry-out chamber 17.

In the embodiment of the present invention shown in FIG. 1, a heating function is added to each of the carburizing and diffusion chambers 12a, 12b, and 12c (or may be added only to the first carburizing and diffusion chamber 12a). Diffusion room 12
Addition of the function of the temperature raising chamber 11 to a, 12b and 12c also increases the temperature of the processed product that could not be sufficiently raised in the temperature raising chamber 11 in the next carburizing and diffusion chamber 12a if the cycle time of the processed product is short. And / or compensates for the temperature drop when the tray or basket 13 is moved between the chambers to increase the quality of the processed product and to meet the required cycle time and required carburizing depth with the minimum required equipment. The present invention provides a continuous vacuum carburizing method and apparatus in which a carburizing and diffusion chamber is effectively used and flexibility is increased. Further, in the embodiment of the present invention shown in FIG. 1, at least one of the plurality of carburizing and diffusion chambers 12a, 12b, and 12c has a different heating time, carburizing and / or diffusion processing time from those of the other carburizing and diffusion chambers. As a result, a continuous vacuum carburizing method and apparatus that saves the amount of use of carburizing gas and effectively uses the carburizing and diffusion chambers 12a, 12b, and 12c to increase flexibility. Since the chamber pressure in the final step of each of the charging chamber 18, the heating chamber 11, and the plurality of carburizing and diffusion chambers 12a, 12b, and 12c was the same as the chamber pressure in the first step of the next chamber, charging was performed. Although the entrance door 31 of the chamber 18, the exit door 36 of the unloading chamber 17, the entrance door 34 and the exit door 35 of the quenching chamber 15 are strictly vacuum sealed doors, the heating chamber 11 and the carburizing and diffusion chambers 12 a, 12 b, 12 c The entrance door 33 and the exit door 34 could be simple vacuum seal doors with lower vacuum sealability.

[Embodiment 1] As an example of deep carburization, a process in the case where the required carbon concentration is 0.3% at a depth of 1.2 mm from the surface will be described with reference to FIG. In this case, if there are three carburizing and diffusion chambers 12a, 12b, and 12c in FIG. 1, a 40-minute cycle is performed. a. Open the entrance door 31 of the loading room 18 and open the tray or basket 1
3 is carried into the charging room 18, and at this time, the entrance door 32 of the heating chamber 11 is closed. The entrance door 31 of the charging room 18 is closed and the inside of the charging room 18 is set to 0.05.
Reduce the pressure to about Kpa. b. The temperature inside the heating chamber 11 is raised to about 1000 ° C and maintained at 0.05 Kpa
The pressure has been reduced to a degree. The tray or basket 13 is carried in from the loading chamber 18 by opening the entrance door 32 of the temperature raising chamber 11. At the same time, the heating chamber 11 exit door 33 is opened, and the three trays or baskets 13 in the heating chamber 11 are sent one pitch forward every 40 minutes of the cycle time, and the first one is the first carburizing diffusion chamber.
It is carried into 12a. The temperature of the iron alloy parts on the tray or basket sent to the carburizing diffusion chamber 12a is raised for 120 minutes to the room temperature of the heating chamber. c. The first carburizing diffusion chamber 12a is maintained at about 1000 ° C and 0.05Kpa
The pressure has been reduced to a degree. After closing the inlet / outlet door and soaking for 5 minutes, supply 25 g / min of ethylene gas as a carburizing gas, perform carburizing for 5 minutes while controlling the indoor pressure at 6 Kpa, stop carburizing gas, reduce the pressure to about 0.05 Kpa, and diffuse for 14 minutes After that, carburizing gas is supplied again at 25 l / min, carburizing is performed by controlling the indoor pressure at 6 Kpa, carburizing gas is stopped, pressure is reduced to about 0.05 Kpa, and diffusion is performed for 14 minutes. d. The tray or basket in the first carburizing diffusion room 12a is the second
It is carried into the carburizing diffusion room 12b. Carburizing diffusion room 12b is about 1000
℃, and reduced to about 0.05Kpa. Close the entrance and exit doors, and after soaking for 5 minutes, use ethylene gas as carburizing gas.
Carburizing 2 while supplying 25 l / min and controlling the indoor pressure at 6Kpa
Carburizing gas is stopped, pressure is reduced to about 0.05 Kpa, and diffusion is performed for 33 minutes. e. The tray or basket in the second carburizing diffusion room 12b is the third
It is carried into the carburizing diffusion room 12c. Carburizing diffusion chamber 12c is about 1000
℃, and reduced to about 0.05Kpa. Close the inlet / outlet door and after soaking for 5 minutes, feed ethylene gas as carburizing gas.
Carburizing while supplying 25 l / min and controlling the indoor pressure at 6 Kpa
Perform 1 minute, stop carburizing gas, reduce pressure to about 0.05 Kpa and perform diffusion for 34 minutes. f. The tray or basket in the third carburizing diffusion room 12c is 0.0
It is carried into the cooling / holding chamber 19, which is decompressed to about 5Kpa. The pressure is increased to 100 kPa with N ₂ gas, the temperature is lowered to 850 ° C, and the cycle time is maintained at the same temperature for 40 minutes.

[Embodiment 2] As an example of shallow carburization, a process in the case where the required carbon concentration is 0.3% at a depth of 0.5 mm from the surface will be described with reference to FIG. In this case, if the carburizing and diffusion chambers 12a, 12b, and 12c in FIG. 1 are three chambers, the cycle is 20 minutes. The tray or basket 13 is processed and forwarded at each cycle time as in the first embodiment. a. Open the entrance door 31 of the loading room 18 and open the tray or basket 1
3 is carried into the charging room 18, and at this time, the entrance door 32 of the heating chamber 11 is closed. The entrance door 31 of the charging room 18 is closed and the inside of the charging room 18 is set to 0.05.
Reduce the pressure to about Kpa. b. The heating chamber 11 is decompressed to about 0.05 Kpa,
The temperature inside 1 is raised to and maintained at about 950 ° C., but the heating time in the heating chamber 11 is 20 minutes and 3 cycles, totaling 60 minutes. In Example 2, the temperature of the iron alloy component does not rise to 950 ° C. c. In the first carburizing diffusion room 12a, the loaded tray or basket is heated at 950 ° C and 0.05Kpa under reduced pressure for 5 minutes.
In the example, it was confirmed that the temperature of the iron alloy component was raised to 950 ° C. by heating for 20 minutes in the first carburizing diffusion chamber 12a. d. In the second carburizing diffusion chamber 12b, after soaking for 5 minutes, carburize for 3 minutes and diffuse for 6 minutes, then carburize again for 2 minutes and diffuse for 4 minutes. e. In the third carburizing diffusion room 12c, after soaking for 6 minutes, carburize for 1 minute and diffuse for 13 minutes. f. The tray or basket 13 in the third carburizing diffusion chamber 12c is carried into the cooling / holding chamber 19. The pressure is increased to 100 kPa with N ₂ gas, the temperature is lowered to 850 ° C, the cycle temperature is maintained for 20 minutes, and then carried into the quenching chamber 15 for oil quenching.

The prior art continuous carburizing furnace 20 of FIG.
28, an independent heating chamber 21 having a plurality of stations, a carburizing chamber 22, a diffusion chamber 23 having a plurality of stations, a cooling chamber / holding chamber 26, and an adjacent gas quenching chamber 25 each separated by a vacuum seal door. Have. Baskets or trays 29 containing workpieces (not shown) are loaded into the loading chamber 28 of the continuous carburizing furnace 20 one by one at a constant time interval by an internal feeding device such as a walking beam (not shown). Then, they are simultaneously quenched sequentially through the quenching chamber 25, and move from left to right as viewed in the drawing inside the apparatus.

As described above, in the vacuum carburizing apparatus, the carburizing time (Tc) and the diffusion time (Td) are strictly controlled, and the respective time ratios (Tc / Td) are set to the carburizing temperature (hereinafter referred to as the processing temperature). )). For example, when the processing temperature is changed from 930 ° C. to 1040 ° C., the ratio (Tc / Td) has to be greatly changed from 1.5 to 3.5. In the prior art continuous carburizing furnace 20 of FIG. 3, three baskets or trays 29 are provided in the heating chamber 21 and one in each subsequent chamber.
Although the example of arranging the pieces is shown, the ratio (Tc / Td) is 1.5
In the case of, the processing time of the other chamber is the ratio (Tc / Td) 0.5
The processing time is extended by 1.5 times, and when the ratio (Tc / Td) is 3.5, it is extended by 3.5 times. Nine baskets or trays 29 are arranged in the heating chamber 21 in FIG. 3 and three in each of the subsequent chambers, and the baskets or trays 29 are continuously arranged one by one at regular time intervals. Assuming that the charging is performed at 20, the processing time in the other chamber is insufficient by the ratio (Tc / Td) 0.5 minutes when the ratio (Tc / Td) is 1.5. When the ratio (Tc / Td) is increased from 1.5 times to 3.5 times, a large time loss occurs even when the number of stations in the carburizing chamber is set in advance.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an elevation in which three carburizing / diffusion chambers serving also as a carburizing chamber, a diffusion chamber, and a heating chamber are applied to a continuous vacuum carburizing furnace for iron alloy parts.

2 (a) shows the cycle time and carburizing depth of the continuous vacuum carburizing furnace of FIG. 1 in Example 1 and FIG.

[Figure 3] ADVANNCED METALS & PROCESSES issued in June 1998
Fig. 5 on page 84KK shows a schematic cross-sectional elevational view of an elevation of a conventional continuous vacuum carburizing furnace.

[Explanation of symbols]

 1 ・ ・ Continuous vacuum carburizing furnace 11 ・ ・ Heating chamber 12a, 12b, 12c ・ ・ Carburizing and diffusion chamber 13 ・ Basket with parts Cooling and holding room

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akio Tamura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Kazuhiro Furuya 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Kenji Kashihara 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Toru Kadone 1-1-1 Fujikoshi Honmachi, Toyama City, Toyama Prefecture Fujikoshi Inn (72) Inventor Sueo Takashima 1-1-1, Fujikoshi Honcho, Toyama City, Toyama Pref., Ltd.Fujikoshi Inn (72) Inventor Shigeru Murakami 1-1-1, Fujikoshi Honmachi, Toyama City, Toyama Pref., Ltd. 1-1-1 Fujikoshi Honcho, Toyama City, Toyama Prefecture (72) Inventor Tetsu Harai 1-1-1, Fujikoshi Honcho, Toyama City, Toyama Prefecture No. 1 Stock Company Fujikoshinai F-term (reference) 4K028 AA01 AC03 AC04

Claims (2)

[Claims] 1. A continuous vacuum carburizing furnace for an iron alloy component including a charging chamber, a heating chamber, a carburizing chamber, a diffusion chamber, a cooling / holding chamber, and a quenching chamber, wherein the carburizing chamber includes a plurality of carburizing chambers. A carburizing / diffusion chamber is also used as the diffusion chamber, and carburizing / diffusion is performed. At least one of the carburizing / diffusion chambers is provided with a heating function, so that the carburizing / diffusion chamber also functions as a heating chamber. A continuous vacuum carburizing method characterized in that: 2. A continuous vacuum carburizing furnace for an iron alloy component including a charging chamber, a heating chamber, a carburizing chamber, a diffusion chamber, a cooling / holding chamber, and a quenching chamber, the carburizing chamber having a plurality of carburizing chambers. A carburizing / diffusion chamber, which is also used as a carburizing / diffusion chamber, performing carburizing / diffusion, and adding a temperature raising function to at least one of the carburizing / diffusion chambers, so that the carburizing / diffusion chamber also functions as a heating chamber. A continuous vacuum carburizing furnace.