JP3845841B2 - Continuous heat treatment furnace - Google Patents

Description

浸炭処理中、第１〜第４仕切扉51〜54のうち、第２仕切扉52は開放され、残りの第１、第３および第４仕切扉51、53、54は閉鎖される。第１仕切扉51により、入口扉41開放時等に浸炭ゾーン雰囲気の外乱が防止される。第３仕切扉53により、拡散ゾーンと降温ゾーンの温度干渉を防止して必要な温度勾配が確保され、かつ雰囲気ガスの干渉が防止される。第４仕切扉54により、出口扉42開放時等に拡散ゾーンを介して降温ゾーンおよび浸炭ゾーン雰囲気の外乱が防止される。
【００２５】
このようにして、浸炭処理においては、第１仕切扉51および第３仕切扉53によって区画された浸炭１ゾーン、浸炭２ゾーンおよび拡散ゾーンが浸炭用特定ゾーンに設定され、線Ａに示す所望の浸炭雰囲気と温度プロファイルを達成することができる。また、降温ゾーンでは空冷装置による強制冷却が行われる。
【００２６】
処理中の雰囲気ガスは、第１〜第５排気管131〜135から炉外に排出される。中でも、第２〜第４排気管132〜134により、浸炭１ゾーン、浸炭２ゾーンおよび拡散ゾーンの各ゾーンから雰囲気ガスが個別に排出されるようになっている。これにより、各ゾーンでの雰囲気ガスのカーボンポテンシャルが異なるが、隣接するゾーンへの雰囲気の影響を少なくすることができる。
【００２７】
つぎに、焼鈍処理を行う場合について説明する。
【００２８】
焼鈍時には、第１〜第７処理ゾーンS1〜S7は、昇温１ゾーン、昇温２ゾーン、均熱ゾーン、徐冷１ゾーン、徐冷２ゾーン、徐冷３ゾーンおよび徐冷４ゾーンをそれぞれ形成する。
【００２９】
焼鈍時には、焼鈍雰囲気ガス源121から、第１〜第３分岐管101〜103および合流管114を介して、第２〜第４給気管82〜84を通じて、昇温２ゾーン、均熱ゾーンおよび徐冷１ゾーンの３つのゾーンにだけ、窒素ガス、プロパンガスおよびエアーの３種類のガスの全てが供給される。これらの３種類の処理ガスが、１種類の焼鈍雰囲気ガスを形成する。窒素ガスは、ベースガスとして用いられる。プロパンガスは、脱炭防止のため、酸素センサの出力信号に基づく雰囲気のカーボンポテンシャル調整用として用いられる。炉内の一酸化炭素濃度を調整するために、エアーが用いられる。
【００３０】
焼鈍処理中、第１〜第４仕切扉51〜54のうち、第３仕切扉53は開放され、残りの第１、第２および第４仕切扉51、52、54は閉鎖される。第１仕切扉51は、入口扉41開放時等に均熱ゾーン雰囲気の外乱防止に有用である。第２仕切扉52により、均熱ゾーンと徐冷１ゾーンの温度勾配の確保のため熱的干渉が防止される。第４仕切扉54は、出口扉42開放時等に均熱ゾーン雰囲気の外乱を防止する。
【００３１】
以上のように、焼鈍処理において、第１仕切扉51および第２仕切扉52によって区画された均熱ゾーンが焼鈍用特定ゾーンに設定され、線Ｂに示す所望のヒートプロファイルの達成することができる。
【００３２】
焼鈍処理中は、第２〜第４排気管132〜134は、閉鎖され、第１および第５排気管131、135を介して、第１および第２分岐管161、162からのみ、雰囲気ガスが排気される。この場合、圧力センサ191、192によって、入口側ベスチブル14および油槽16内の圧力が検出され、この検出信号に基づいて、圧力調整弁181、182が自動的に開度調整（０〜１００％）される。
【００３３】
焼鈍処理において雰囲気ガスが自動的に排出されることにより、炉内に供給される無酸化雰囲気ガスは、炉内圧を維持できるだけの必要最小量であって良い。 また、炉の入口側および出口側の２か所から排出されるガスの量を個別に調整することにより、炉内雰囲気ガスの流れ方向を可変に制御できる。
【００３４】
上記において、浸炭と焼鈍を切り替え実施可能な条件を説明した。上記開示すみ内容以外にも、ゾーン構成、ゾーン長、ゾーン出力（処理温度により異なる）、加熱と冷却をどのように併設させるか等の設計的配慮が払われていることは勿論である。
【００３５】
【発明の効果】
この発明によれば、１つの炉で、浸炭および焼鈍の熱処理作業に対応することができて便利であり、設備費が安価に済む連続熱処理炉が提供される。
【図面の簡単な説明】
【図１】 この発明による熱処理炉の垂直縦断面図である。
【図２】 同熱処理炉の給気および排気配管経路を示す説明図である。
【図３】 同熱処理炉によって処理されるヒートプロファイルの説明図である。
【符号の説明】
11 炉本体
51〜54 仕切扉 [0001]
BACKGROUND OF THE INVENTION
The present invention relates to a continuous heat treatment furnace used for performing heat treatment such as carburizing and annealing in a predetermined atmosphere on steel, metal parts and the like.
[0002]
[Prior art]
As this type of heat treatment furnace, a continuous carburizing furnace for performing carburizing specially, a continuous annealing furnace for performing annealing specially, and the like are known.
[0003]
[Problems to be solved by the invention]
In order to install the continuous carburizing furnace and the continuous annealing furnace separately, a large space is required, and the equipment cost is high. Furthermore, it is not suitable when it is necessary to run these processes in a relatively small lot.
[0004]
An object of the present invention is to provide a continuous heat treatment furnace and a heat treatment method which can be conveniently used for carburization and annealing heat treatment operations in one furnace, and can be reduced in equipment cost.
[0005]
[Means for Solving the Problems]
The continuous heat treatment furnace according to the present invention has an inlet at one end and an outlet at the other end, a furnace body provided so that a plurality of processing zones are successively connected from the inlet to the outlet, and a workpiece in each processing zone. Selectively between the transporting means for transporting the work so that it can be passed over time, a heating means for individually controlling the temperature of each processing zone, a supply means for supplying atmospheric gas to a predetermined processing zone, and a processing zone A continuous heat treatment furnace in which a workpiece is sequentially conveyed into each processing zone through a boundary between the connected processing zones, which is either carburized or annealed. A partition that is provided in a carburizing zone in a region that becomes a specific carburizing zone during carburizing, and a soaking zone that can be partitioned from a slow cooling zone during annealing. And a forced cooling means provided in a slow cooling zone outside the area that becomes the specific annealing zone during annealing, and a forced cooling means provided in the area that becomes the cooling zone during carburization, and outside the area that becomes the specific annealing zone during annealing. The diffusion zone is provided with a partition door provided so that the diffusion zone can be separated from the temperature lowering zone during carburizing .
[0006]
In the continuous heat treatment furnace according to the present invention, the types of heat treatment are specialized in carburizing and annealing, and both of the heat treatments can be performed very easily by using one furnace .
[0007]
The furnace body is provided with a plurality of atmospheric gas inlets and outlets in the furnace length direction. Opening and closing of these inlets and outlets can be performed individually according to the type of heat treatment. If it is selectable, heat treatment can be efficiently performed by selecting appropriate air supply and exhaust ports according to the type of heat treatment.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0009]
In the following description, “front and rear” refers to FIG. 1 as a reference, the left side is front, and the opposite side is rear, and left and right are left and right when viewed from the front.
[0010]
Referring to FIG. 1, the heat treatment furnace has a horizontal cylindrical furnace body 11 extending in the front-rear direction. An inlet 12 is provided at the front end of the furnace body 11, and an outlet 13 is provided at the rear end thereof.
[0011]
An inlet purge chamber 15 is connected to the inlet 12 via an inlet-side vestable 14. An oil tank 16 is connected to the outlet 13. An outlet purge chamber 19 is connected to the oil tank 16.
[0012]
A large number of conveying rollers 21 are provided in the furnace body 11 so as to be continuously arranged from the front to the rear, and six first to sixth partition walls 31 to 36 are sequentially provided from the front to the rear. The furnace body 11 is partitioned into seven first to seventh processing zones S1 to S7 by the first to sixth partition walls 31 to 36 from the inlet 12 to the outlet 13. Each of the partition walls 31 to 36 has a workpiece passage communication port.
[0013]
The conveyance roller 21 is intermittently driven so that the workpiece is stopped for a predetermined time in the first to seventh processing zones S1 to S7, so-called tact conveyance. Further, instead of intermittent driving, the roller 21 may be driven continuously. For example, only when one workpiece passes through the partition walls 31 to 36, only the roller 21 on which the workpiece is placed is set to high-speed feeding, and the other rollers 21 are set to low-speed feeding.
[0014]
An entrance door 41 is provided at the entrance 12, and an exit door 42 is provided at the exit 13. A first partition door 51 is provided on the first partition wall 31, a second partition door 52 is provided on the third partition wall 33, a third partition door 53 is provided on the fifth partition wall 35, and a fourth partition door 54 is provided on the sixth partition wall 36. Are provided. The entrance door 41, the exit door 42, the second partition door 52 and the third partition door 53 are opened and closed by being lifted and lowered in a vertical state, and the first partition door 51 and the fourth partition door 54 are Is opened and closed by being lifted and lowered in an inclined state.
[0015]
The first to fourth partition doors 51 to 54 are automatically opened and closed by an actuator such as a fluid pressure cylinder. In addition, the first to fourth partition doors 51 to 54 are provided with small communication ports as necessary, through which exhaust flow and pressure equalization are possible.
[0016]
Referring to FIG. 2, first to seventh air supply ports 61 to 67 are provided in the furnace body 11 so as to communicate with the first to seventh processing zones S <b> 1 to S <b> 7, respectively. On the other hand, the furnace body 11 is provided with five first to fifth exhaust ports 71 to 75. The first exhaust port 71 is in the inlet-side vestable 14 and the second exhaust port 72 is in the third processing zone S3. The third exhaust port 73 is connected to the fourth processing zone S4, the fourth exhaust port 74 is connected to the fifth processing zone S5, and the fifth exhaust port 75 is connected to the oil tank 16.
[0017]
The outlet ends of the first to seventh air supply pipes 81 to 87 are connected to the first to seventh air supply ports 61 to 67, respectively. The inlet ends of the first to seventh supply pipes 81 to 87 are connected to a carburizing atmosphere gas supply source 91, respectively. Near the inlet ends of the second to fourth supply pipes, outlet ends of the first to third branch pipes 101 to 103 are connected. The first to third branch pipes 101 to 103 are provided with on-off valves 111 to 113, respectively. The inlet ends of the first to third branch pipes 101 to 103 are connected to the annealing atmosphere gas source 121 via the junction pipe 114.
[0018]
First to fifth exhaust pipes 131 to 135 are connected to the first to fifth exhaust ports 71 to 75, respectively. The first to fifth exhaust pipes 131 to 135 are provided with on-off valves 141 to 145 and flow control valves 151 to 155, respectively. A first branch pipe 161 and a second branch pipe 162 are connected upstream of the on-off valves 141 and 145 of the first exhaust pipe 131 and the fifth exhaust pipe 135, respectively. The first branch pipe 161 and the second branch pipe 162 are provided with on-off valves 171, 172 and pressure adjusting valves 181, 182 respectively. In addition, pressure switches 191 and 192 are provided on the inlet side vestable 14 and the oil tank 16, respectively.
[0019]
A heater and an air cooling device (not shown) are provided at appropriate positions of the furnace body 11. With these devices, the first to seventh processing zones S1 to S7 can be raised or lowered to a required temperature. For example, when a radiant tube is used as the heater, the heater can also be used as a cooling device by forcibly feeding cooling air into the tube. You may use the other apparatus which can be heated and cooled.
[0020]
As an example of heat treatment, a specific example in the case of carburizing and annealing will be described below.
[0021]
FIG. 3 shows a heat profile during heat treatment. In FIG. 3, the temperature of the workpiece at the time of carburizing is indicated by a line A, and the temperature of the workpiece at the time of annealing is indicated by a line B.
[0022]
In the case of carburizing, the first to seventh treatment zones S1 to S7 form a temperature rise zone 1, a temperature rise zone 2, a carburization zone 1, a carburization zone 2, a diffusion zone, a temperature fall zone, and a soaking zone, respectively.
[0023]
At the time of carburizing, each type of gas shown in Table 1 is supplied from the carburizing atmosphere gas source 91 through the first to seventh supply pipes 81 to 87 to the first to seventh processing zones S1 to S7. In Table 1, circles indicate supply. An endothermic gas (RX gas) is used as the base gas in this case. A combination of these plural types of processing gases forms one type of carburizing atmosphere gas.
[0024]
[Table 1]

During the carburizing process, among the first to fourth partition doors 51 to 54, the second partition door 52 is opened, and the remaining first, third, and fourth partition doors 51, 53, and 54 are closed. The first partition door 51 prevents disturbance of the carburizing zone atmosphere when the entrance door 41 is opened. The third partition door 53 prevents the temperature interference between the diffusion zone and the temperature lowering zone, ensures a necessary temperature gradient, and prevents the atmospheric gas from interfering. The fourth partition door 54 prevents disturbance of the temperature lowering zone and the carburizing zone atmosphere through the diffusion zone when the outlet door 42 is opened.
[0025]
Thus, in the carburizing process, the carburized 1 zone, the carburized 2 zone, and the diffusion zone defined by the first partition door 51 and the third partition door 53 are set as the carburized specific zone, and the desired car- Carburizing atmosphere and temperature profile can be achieved. In the temperature lowering zone, forced cooling is performed by an air cooling device.
[0026]
The atmospheric gas being processed is exhausted from the first to fifth exhaust pipes 131 to 135 to the outside of the furnace. Among these, the atmospheric gas is individually discharged from the carburizing 1 zone, carburizing 2 zone, and diffusion zone by the second to fourth exhaust pipes 132 to 134. Thereby, although the carbon potential of the atmospheric gas in each zone differs, the influence of the atmosphere on the adjacent zone can be reduced.
[0027]
Next, the case where the annealing process is performed will be described.
[0028]
At the time of annealing, the first to seventh treatment zones S1 to S7 include a temperature rising zone 1, a temperature rising zone 2, a soaking zone, a slow cooling zone 1, a slow cooling zone 2, a slow cooling zone 3 and a slow cooling zone 4 respectively. Form.
[0029]
At the time of annealing, from the annealing atmosphere gas source 121, through the first to third branch pipes 101 to 103 and the junction pipe 114, through the second to fourth supply pipes 82 to 84, the temperature rising zone, the soaking zone and the gradual zone All three types of gases, nitrogen gas, propane gas and air, are supplied to only the three zones of the cold one zone. These three kinds of processing gases form one kind of annealing atmosphere gas. Nitrogen gas is used as a base gas. Propane gas is used for adjusting the carbon potential of the atmosphere based on the output signal of the oxygen sensor in order to prevent decarburization. Air is used to adjust the carbon monoxide concentration in the furnace.
[0030]
During the annealing process, among the first to fourth partition doors 51 to 54, the third partition door 53 is opened, and the remaining first, second and fourth partition doors 51, 52 and 54 are closed. The first partition door 51 is useful for preventing disturbance in the soaking zone atmosphere when the entrance door 41 is opened. The second partition door 52 prevents thermal interference in order to ensure a temperature gradient between the soaking zone and the slow cooling 1 zone. The fourth partition door 54 prevents disturbance in the soaking zone atmosphere when the exit door 42 is opened.
[0031]
As described above, in the annealing process, the soaking zone defined by the first partition door 51 and the second partition door 52 is set as the specific zone for annealing, and the desired heat profile shown by the line B can be achieved. .
[0032]
During the annealing process, the second to fourth exhaust pipes 132 to 134 are closed, and the atmospheric gas is supplied only from the first and second branch pipes 161 and 162 through the first and fifth exhaust pipes 131 and 135. Exhausted. In this case, the pressure sensors 191 and 192 detect the pressure in the inlet side vestable 14 and the oil tank 16, and the pressure adjustment valves 181 and 182 automatically adjust the opening degree (0 to 100%) based on this detection signal. Is done.
[0033]
By automatically discharging the atmospheric gas in the annealing process, the non-oxidizing atmospheric gas supplied into the furnace may be a minimum amount necessary to maintain the furnace pressure. Further, the flow direction of the atmospheric gas in the furnace can be variably controlled by individually adjusting the amount of gas discharged from two places on the inlet side and the outlet side of the furnace.
[0034]
In the above, the conditions that can be switched between carburizing and annealing have been described. In addition to the contents disclosed above, it is a matter of course that design considerations such as zone configuration, zone length, zone output (depending on the processing temperature), and how heating and cooling are provided together are taken.
[0035]
【The invention's effect】
According to the present invention, a continuous heat treatment furnace can be provided that can handle carburization and annealing heat treatment operations with one furnace, is convenient, and requires a low equipment cost.
[Brief description of the drawings]
FIG. 1 is a vertical longitudinal sectional view of a heat treatment furnace according to the present invention.
FIG. 2 is an explanatory view showing an air supply and exhaust piping path of the heat treatment furnace.
FIG. 3 is an explanatory diagram of a heat profile processed by the heat treatment furnace.
[Explanation of symbols]
11 Furnace body
51-54 partition door

Claims (2)

A furnace body that has an inlet at one end and an outlet at the other end, and a plurality of processing zones are sequentially connected from the inlet to the outlet, so that the workpiece can pass through each processing zone over a predetermined time. Conveying means for conveying workpieces, heating means for individually controlling the temperature of each processing zone, supply means for supplying atmospheric gas to a predetermined processing zone, and a plurality of partition doors selectively provided between the processing zones And a continuous heat treatment furnace in which workpieces are sequentially conveyed into each processing zone through a boundary between the connected processing zones, and selectively performing either carburizing or annealing. For carburizing, it is provided in the carburizing zone in the area that becomes the specific carburizing zone during carburizing, and the partition door provided so that the soaking zone can be separated from the slow cooling zone during annealing, and for annealing during annealing Specific zone Is provided in the slow cooling zone outside the zone, and when carburized, it is provided in the forced cooling means provided in the zone that will be the cooling zone, and during annealing, it is provided in the slow cooling zone outside the zone that will be the specific zone for annealing. Is a continuous heat treatment furnace characterized in that the diffusion zone has a partition door provided so as to be partitioned from the cooling zone . The continuous heat treatment furnace according to claim 1 , wherein a plurality of atmospheric gas inlets and outlets are provided in the furnace length direction so that they can be individually selected according to carburizing or annealing .

Images