JP4540406B2 - Multi-stage continuous carburizing and quenching furnace and continuous carburizing and quenching method - Google Patents

Description

  The present invention relates to a carburizing and quenching furnace and a carburizing and quenching method used for carburizing and quenching, and more particularly to a multi-stage continuous carburizing and quenching furnace and a continuous carburizing and quenching method.

  Carburizing and quenching is widely performed on metal materials such as mechanical parts that require toughness, wear resistance, and fatigue strength. A gas carburizing process using a carburizing gas is widely used for the carburizing and quenching process. Gas carburizing is a heat treatment that diffuses and infiltrates carbon into the surface of a metal material by heating the metal material to be treated to a high temperature in a carburizing gas atmosphere, and the interior is rich in toughness by the subsequent quenching treatment. The surface is hard and wear resistant.

  Here, in general, the quenching treatment in which the metal material is immersed in the quenching medium completes the quenching transformation by immersing the metal material in the quenching medium for about 5 minutes, and the time required for the quenching cycle is about 10 minutes. Since the carburizing cycle requires about 30 to 60 minutes, there is a large difference between the time required for the quenching cycle and the time required for the carburizing cycle, and the cycle of the entire continuous carburizing and quenching process is set according to the carburizing cycle. A waiting time is arranged between the quenching cycles, making efficient continuous carburizing and quenching difficult.

  On the other hand, for such continuous carburizing treatment, for example, a long continuous carburizing furnace in which a carburizing zone is formed on the upstream side of the furnace and a diffusion zone is formed on the downstream side of the furnace is used, and the metal material is transported by a common transporting device. However, carburizing zone is carburized to the surface of the metal material, and then carbon is diffused inside the metal material in the diffusion zone. However, a long continuous carburizing furnace is required to carburize and diffuse carbon while sequentially transporting metal materials with a common transport device, and a long installation place is required to install the continuous carburizing furnace. Become.

  Therefore, in the carburizing zone, the metal material is sequentially conveyed and carburized by a single conveying device, and in the diffusion zone, the metal material carburized in the carburizing zone is distributed and conveyed to a plurality of conveying devices. A continuous carburizing furnace is known in which the diffusion zone is shortened by carbon diffusing into a metal material in parallel (see, for example, Patent Document 1).

  In addition, it has a common conveying device that sequentially conveys the metal material and a carburizing furnace in which a carburizing zone is formed in accordance with the carburizing treatment of the metal material having a deep carburizing depth. When a metal material with a shallow carburizing depth follows a metal material with a deep carburizing depth, the difference in time spent on the carburizing process, a distance from the previous metal material is carried in, and then the metal material with a shallow carburizing depth is used. There is known a continuous carburizing furnace in which various carburizing depths of metal materials can be continuously carburized in a single carburizing furnace by transferring them so as to fill the space ahead when passing through the carburizing zone (for example, , See Patent Document 2).

  Further, as schematically shown in FIG. 11, a plurality of heat treatment pallets 101 on which metal materials are placed are stacked, and the plurality of stacked heat treatment pallets 101 are simultaneously conveyed in the carburizing zone 103 of the carburizing furnace 102 by a conveyor or the like. Carburized and carbon diffused simultaneously with each metal material transported by the apparatus 106 and placed on the plurality of stacked heat treatment pallets 101, and gradually cooled in the temperature lowering zone 105, and then the carburized metal material is mounted. There is also known a multi-stage continuous carburizing furnace in which a plurality of heat-treated pallets 101 in a stacked state are simultaneously immersed in oil as a quenching medium in a quenching zone 107 and subjected to oil quenching.

Japanese Patent Laid-Open No. 10-204607 JP-A-2001-207253

  According to the continuous carburizing furnace described in Patent Document 1, the carburizing zone sequentially conveys and carburizes metal materials by a single conveying device, and the diffusion zone disperses and conveys the carburized metallic material to a plurality of conveying devices. The continuous carburizing furnace can be shortened by carbon diffusion.

  However, since the plurality of transfer devices are arranged in parallel in the diffusion zone, the width direction of the diffusion zone becomes long, and the metal material is sequentially transferred by the single transfer device and carburized by the carburizing zone, which is efficient. Carburizing treatment cannot be obtained, and there is a concern that productivity will decline.

  On the other hand, according to the continuous carburizing furnace described in Patent Document 2, various carburizing depth metal materials can be continuously carburized in a single carburizing furnace. However, since a metal material is sequentially conveyed and carburized by a single conveying device, an efficient carburizing process cannot be obtained and there is a concern about a decrease in productivity.

  On the other hand, according to the multi-stage continuous carburizing furnace shown in FIG. 11, each heat treatment pallet 101 on which a metal material is placed is stacked in multiple stages, and a plurality of the multi-stage heat treatment pallets 101 are simultaneously conveyed in the carburizing zone 103 of the continuous carburizing furnace 102. The metal materials mounted on the plurality of heat treatment pallets 101 are simultaneously carburized and carbon diffused, and the metal materials mounted on the plurality of heat treatment pallets 101 stacked in multiple stages are simultaneously quenched in the quenching zone 107. Carburizing and quenching can be performed.

  However, since the respective metal materials mounted on the plurality of stacked heat treatment pallets 101 are simultaneously carburized in the carburizing zone 103 of the continuous carburizing furnace 102, the carburizing in the carburizing zone 103 is performed by the stacked heat treating pallets 101. The flow of the carburizing gas is affected, and the position of each heat treatment pallet 101 stacked, that is, the flow of the carburizing gas varies depending on the stage, and the carburizing temperature also varies with the disturbance of the carburizing gas. As a result, the amount of carbon that enters the surface of the metal material placed on the heat treatment pallet 101 at each stage varies, which makes it impossible to achieve a stable and uniform carburizing process.

  Further, in the quenching zone 107, the metal materials respectively placed on the stacked heat treatment pallets 101 are immersed and hardened in oil in the stacked state. Deviation occurs in the lower and upper heat treatment pallets 101, and between the metal material loaded on the lower heat treatment pallet 101 and the metal material loaded on the upper heat treatment pallet 101 under the influence of various oils. There is a concern that a difference in cooling occurs due to a difference in the progress of the transformation, a variation occurs in the deformation caused by quenching between the metal materials, and the dimensional accuracy of the quenched metal material becomes unstable. The

  Accordingly, an object of the present invention made in view of the above points is to provide a multi-stage continuous carburizing and quenching furnace capable of performing high-quality carburizing and quenching capable of obtaining stable and uniform carburizing treatment and ensuring dimensional accuracy while being excellent in productivity. It is to provide a continuous carburizing and quenching method.

  The invention of the multi-stage continuous carburizing and quenching furnace according to claim 1, which achieves the above object, sequentially conveys the carburizing zone, the diffusion zone, and the temperature-falling zone in the furnace to carburize the metal material surface and to the inside of the metal material. In a continuous carburizing and quenching furnace in which a carburizing process for carbon diffusion and a quenching process in which the carburized metal material is quenched in a quenching medium in a quenching zone are continuously performed from the upstream side in the furnace to the downstream side. A carburizing zone, a diffusion zone, and a temperature lowering zone are sequentially arranged on the side, and a multi-stage carburizing machine having a plurality of conveying devices that divide the furnace into multi-stage carburizing furnace areas that continue from the carburizing zone to the temperature lowering zone. Carburizing on the upstream side of the transfer device in the carburizing furnace area at an interval corresponding to the quenching cycle according to the order of the carburizing furnace area arranged in advance and arranged in the upstream side of the multi-stage carburizing furnace A workpiece charging device for sequentially charging a heat treatment pallet loaded with a metal material to be charged, and a carburizing zone disposed downstream of the multi-stage carburizing furnace and charged into each carburizing furnace zone by the workpiece charging device, respectively. In addition, the heat treatment pallet loaded with the carburized metal material transported to the cooling zone through the diffusion zone is quenched in a continuous quenching cycle from the cooling zone in each carburizing furnace area in accordance with the carburizing furnace area order set above. A quenching zone in which the metal material is quenched by being immersed in a medium.

  The invention according to claim 2 is characterized in that, in the multi-stage continuous carburizing and quenching furnace according to claim 1, the transfer device for partitioning between the carburizing furnace zones allows airflow between the carburizing furnace areas. To do.

  According to a third aspect of the present invention, in the multistage continuous carburizing and quenching furnace of the second aspect, the conveying device is a roller conveyor.

  The invention according to claim 4 is the multi-stage continuous carburizing and quenching furnace according to any one of claims 1 to 3, wherein the upstream end of each carburizing furnace area, between the carburizing zone and the diffusion zone, and between the diffusion zone and the cooling zone. A plurality of open / close partition means are provided that allow the movement of the heat treatment pallet to be opened when the heat treatment pallet that is partitioned between each other and passes the portion of the heat treatment pallet loaded with the metal material.

  The invention according to claim 5 is the multistage continuous carburizing and quenching furnace according to any one of claims 1 to 4, wherein the quenching zone is arranged downstream of the multistage carburizing furnace and arranged in the order of the carburizing furnace areas set. In accordance with the above, the heat treatment pallet loaded with the carburized metal material carried from the cooling zone of each carburizing furnace area is immersed in the quenching medium to quench the metal material, and the heat treatment pallet loaded with the quenched metal material is A quenching elevator for carrying out is provided.

  The invention of the continuous carburizing and quenching method according to claim 6, which achieves the above object, comprises sequentially carburizing a carburizing zone, a diffusion zone, and a cooling zone in a furnace to carburize the surface of the metal material and carbon into the metal material. In a continuous carburizing and quenching method in which a carburizing process for diffusion and a quenching process in which the carburized metal material is immersed in a quenching medium are continuously performed, a carburizing zone continuously from the upstream side to the downstream side in the furnace, A diffusion zone and a temperature lowering zone are arranged in order, and a multi-stage carburizing furnace having a plurality of transfer devices for dividing the inside of the furnace into a multi-stage carburizing furnace area continuous from the carburizing zone to the temperature lowering zone, respectively, is set in advance. In accordance with the order of carburizing furnace area, heat treatment pallets loaded with metal materials to be carburized and quenched are sequentially placed on the upstream side of the transfer device in the carburizing furnace area at intervals equivalent to the quenching cycle. In both cases, the heat treatment pallet loaded with each carburizing furnace zone is loaded into the carburizing furnace zone and loaded with the carburized metal material that has been transported to the cooling zone through the carburizing zone and the diffusion zone. The metal material is subjected to a quenching treatment by being immersed in a quenching medium in a quenching cycle continuous from a temperature lowering zone of each carburizing furnace area.

  According to the first aspect of the present invention, a heat treatment pallet on which a metal material to be carburized is loaded in each carburizing area at intervals corresponding to a quenching cycle in accordance with a preset carburizing furnace area order, Carburizing treatment was performed in parallel in each carburizing zone and diffusion zone, and after gradually cooling in each cooling zone, the metal material carburized from the cooling zone in each carburizing furnace area was mounted according to the order of carburizing furnace area set above. Since the heat treatment pallet is immersed in the quenching medium in the quenching cycle to quench the metal material, the quenching process can be sequentially performed in a continuous quenching cycle without interruption, and a carburization quenching process with excellent productivity can be obtained.

  Furthermore, by transferring the heat treatment pallet in the carburized zone and diffusion zone of each carburizing area in a flat state by the respective transfer devices, there is no variation in the carbon amount and carbon diffusion entering the metal surface mounted on each heat treatment pallet. Good carburizing treatment can be performed in parallel. In addition, the heat treatment pallet loaded with the metal material gradually cooled in each temperature drop zone is dipped in the quenching medium separately, so that the timing of charging into the quenching medium can be ensured, and cooling between the metal materials is possible. Without any difference, the variation in deformation caused by quenching between the metal materials is suppressed, the dimensional accuracy of the metal material after treatment is stabilized, and a high-quality carburizing quenching process can be ensured. Moreover, each carburizing area divided by each conveying device is arranged in a multi-stage shape, and the length in the width direction of the carburizing furnace can be suppressed, and a reduction in the installation location can be expected.

  According to the invention of claim 2, the temperature and atmosphere of the entire carburizing zone in the furnace are good without the flow of the airflow containing the carburizing gas between the carburizing zones in each carburizing furnace area being affected by each conveying device. It is possible to control the air flow between the diffusion zones in the carburizing furnace area without being affected by each conveying device, and it is possible to control the temperature and atmosphere in the entire diffusion zone in the furnace to a good state.

  According to invention of Claim 3, the conveying apparatus which accept | permits the distribution | circulation of the airflow between each carburizing furnace area of Claim 2 by the existing roller conveyor can be comprised easily.

  According to the invention of claim 4, the upstream end of each carburizing furnace area, between the carburizing zone and the diffusion zone, between the diffusion zone and the cooling zone, and opened when passing through a heat treatment pallet loaded with a metal material. By providing the open / close section means, the temperature and atmosphere of each carburizing zone and each diffusion zone in the furnace can be controlled efficiently.

  According to the invention of claim 5, the carburized metal material carried from the cooling zone of each carburizing furnace area is installed in the quenching zone according to the carburizing furnace area order arranged and set downstream of the multi-stage carburizing furnace. The heat treatment pallet is immersed in a quenching medium to quench the metal material, and the quenching treatment can be easily performed by providing a quenching elevator for carrying out the heat treatment pallet on which the quenched metal material is mounted.

  According to the invention of claim 6, a heat treatment pallet on which a metal material to be carburized is loaded in each carburizing area at an interval corresponding to a quenching cycle according to a preset carburizing furnace area order, Carburizing treatment is performed in parallel in the carburizing zone and the diffusion zone, and after gradually cooling in each cooling zone, the heat treatment pallet from the cooling zone in each carburizing furnace area is quenched in the quenching cycle in accordance with the preset carburizing furnace area order. Since the metal material is quenched by dipping inside, it can be sequentially quenched in a continuous quenching cycle without interruption, and carburizing and quenching with excellent productivity can be achieved.

  Hereinafter, an embodiment of a multistage continuous carburizing furnace and a continuous carburizing method according to the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic explanatory diagram of a multistage continuous carburizing furnace 1 according to the present embodiment. Reference numeral 10 denotes a multi-stage carburizing furnace. In the multi-stage carburizing furnace 10, a carburizing zone 11 is disposed on the upstream side in the furnace, and a diffusion zone 12 and a cooling zone 13 are continuously formed on the downstream side of the carburizing zone 11.

  A first-stage transport roller conveyor 14-1 serving as a first-stage transport device is disposed at the bottom of the multi-stage carburizing furnace 10 continuously from the upstream end of the carburizing zone 11 to the downstream end of the diffusion zone 12. The second to fourth transport roller conveyors 14-2 to 14-4, which are the second to fourth transport devices, are sequentially arranged at equal intervals above the first transport roller conveyor 14-1. Has been. Each of the first-stage to fourth-stage transport roller conveyors 14-1 to 14-4 is driven independently.

  The inside of the carburizing zone 11 is divided into the first to fourth carburizing zones 11-1 to 11-4 in order from the lower side by the first to fourth transport roller conveyors 14-1 to 14-4. Is done.

  In the first stage carburizing zone 11-1, the heat treatment pallets 50 that are sequentially transported from the upstream side to the downstream side by the first transport roller conveyor 14-1 are placed at the first stop position 11-1a to the sixth stop position 11-1f. A stopper (not shown) for stopping and maintaining at each stop position is provided, and a pallet detection sensor 11-1s for detecting the presence or absence of the heat treatment pallet 50 at the first stop position 11-1a is provided.

  Similarly, in each of the carburizing zones 11-2 to 11-4 of the second stage to the fourth stage, the heat treatment conveyed by the conveying roller conveyors 14-2 to 14-4 of the second stage to the fourth stage, respectively. Stoppers (not shown) for stopping and maintaining the pallet 50 at the first stop positions 11-2a, 11-3a, 11-4a to the sixth stop positions 11-2f, 11-3f, 11-4f are provided. In addition, pallet detection sensors 11-2s to 11-4s for detecting the presence or absence of the heat treatment pallet 50 at the first stop positions 11-2a to 11-4a are provided.

  In the diffusion zone 12, as in the case of the carburizing zone 11, the diffusion zones 12- in the first to fourth stages are sequentially arranged from the lower side by the conveying roller conveyors 14-1 to 14-4 in the first to fourth stages. 1-12-4. Each of the first to fourth transport roller conveyors 14-1 to 14-4 is constituted by an existing roller conveyor for a carburizing furnace, and a plurality of rollers disposed with a gap therebetween are rotationally driven. Thus, the heat treatment pallet 50 loaded with the loaded metal member is conveyed, and the flow of an air flow such as a carburizing gas is allowed between the rollers.

  In the first stage diffusion zone 12-1, the heat treatment pallet 50 sequentially conveyed from the upstream side to the downstream side by the first conveying roller conveyor 14-1 is placed at the first stop position 12-1a to the third stop position 12-1c. A stopper (not shown) for stopping and maintaining at each stop position is provided. Similarly, in each of the diffusion zones 12-2 to 12-4 of the second stage to the fourth stage, the heat treatment pallet 50 conveyed by the respective conveyance roller conveyors 14-2 to 14-4 of the second stage to the fourth stage. Stoppers (not shown) for stopping and maintaining the heat treatment pallet 50 at the respective stop positions of the first stop positions 12-2a, 12-3a, 12-4a to the third stop positions 12-2c, 12-3c, 12-4c are provided. ing.

  Further, in the temperature lowering zone 13, a first-stage unloading roller conveyor 15 that constitutes a first-stage conveying device together with the first-stage conveying roller conveyor 14-1 continuously downstream of the first-stage conveying roller conveyor 14-1. -1 is arranged. The second-stage to fourth-stage carry-out roller conveyors 15-2 to 15-4 constituting the second-stage to fourth-stage transport devices are sequentially arranged at equal intervals above the first-stage carry-out conveyor 15-1. It is continuously arranged on the downstream side of each of the second to fourth transport roller conveyors 14-2 to 14-4, and is carried by the first to fourth transport roller conveyors 15-1 to 15-4. The temperature decreasing zone 13 is divided into first to fourth temperature decreasing zones 13-1 to 13-4 in order from the lower side. Each of these carry-out roller conveyors 15-1 to 15-4 is driven independently.

  An upstream end serving as an inlet of the first stage carburizing zone 11-1, a downstream end of the first stage carburizing zone 11-1 and an upstream end of the first stage diffusion zone 12-1, and a first stage diffusion zone 12-1. Between the downstream end of the first stage and the upstream end of the first stage cooling zone 13-1, and at the downstream end of the first stage cooling zone 13-1, doors 16-1, 17-1, 18-1 and 19-1 are provided to be openable and closable, and a first stage carburizing furnace area I is formed by the first stage carburizing zone 11-1, the first stage diffusion zone 12-1, and the first stage cooling zone 13-1. Is done.

  Similarly, the upstream end serving as the inlet of the second stage carburizing zone 11-2, between the second stage carburizing zone 11-2 and the second stage diffusion zone 12-2, and the second stage diffusion zone 12-2 and the second stage. Doors 16-2, 17-2, 18-2, and 19-2, which are open / close partition means for partitioning each of the temperature-falling zone 13-2 and the downstream end of the second-stage cooling zone 13-2, are opened and closed. A second-stage carburizing furnace area II is formed by the second-stage carburizing zone 11-2, the second-stage diffusion zone 12-2, and the second-stage cooling temperature zone 13-2.

  The upstream end of the third stage carburizing zone 11-3, between the third stage carburizing zone 11-3 and the third stage diffusion zone 12-3, the third stage diffusion zone 12-3 and the third stage temperature decreasing zone 13-3 , Doors 16-3, 17-3, 18-3, 19-3 are provided at the downstream end of the third-stage cooling zone 13-3 so as to be openable and closable, and the third-stage carburizing zone 11-3, third A third stage carburizing furnace area III is formed by the stage diffusion zone 12-3 and the third stage cooling zone 13-3. Similarly, at the upstream end of the fourth stage carburizing zone 11-4, between the fourth stage carburizing zone 11-4 and the fourth stage diffusion zone 12-4, the fourth stage diffusion zone 12-4 and the fourth stage temperature lowering zone 13 -4, doors 16-4, 17-4, 18-4, 19-4 are provided at the downstream end of the fourth stage temperature drop zone 13-4 so as to be openable and closable. The fourth stage carburizing furnace area IV is formed by the fourth stage diffusion zone 12-4 and the fourth stage temperature lowering zone 13-4.

  The carburizing zone 11 is partitioned from the diffusion zone 12 by closing the doors 16-1 to 16-4 on the upstream side and closing the doors 17-1 to 17-4 on the downstream side, and the insides are carburized from each other. The first to fourth stages are provided by the first to fourth transport roller conveyors 14-1 to 14-4 that can secure the airflow between the furnace areas I and II, II and III, and III and IV. Are carburized zones 11-1 to 11-4.

  In the diffusion zone 12, it is divided from the carburizing zone 11 by closing the doors 17-1 to 17-4 on the upstream side, and is divided from the temperature lowering zone 13 by closing the doors 18-1 to 18-4 on the downstream side. And it is divided into each diffusion zone 12-1 to 12-4 of the 1st stage-the 4th stage by each conveyance roller conveyor 14-1 to 14-4 of the 1st stage-the 4th stage.

  A metal material that has been carburized on the downstream side of the multi-stage carburizing furnace 10 in which the first-stage carburizing area I, the second-stage carburizing area II, the third-stage carburizing area III, and the fourth-stage carburizing area IV are arranged in a stack. A quenching zone 21 is disposed in which oil quenching is performed by putting it in oil that is a quenching medium.

  Work input means for supplying the heat treatment pallet 50 carried by the carry-in roller conveyor 29, which is carry-in means, to the first to fourth carburization zones 11-1 to 11-4 on the upstream side of the multi-stage carburizing furnace 10. A certain carry-in elevator 25 is arranged.

  On the other hand, a quenching elevator 27 is disposed downstream of the multi-stage carburizing furnace 10. By this quenching elevator 27, the first to fourth stage temperature drop zones 13-1 to 13-4 are carried out by the first stage to fourth stage carry-out roller conveyors 15-1 to 15-4. The heat treatment pallet 50 is collected, lowered, and immersed in oil that is a quenching medium in the quenching zone 21 for a predetermined time to quench the metal material with oil. Further, after the quenching process, the heat treatment pallet 50 is raised by the quenching elevator 27, and is carried out from the multistage continuous carburizing furnace 1 by the carry-out roller conveyor 30 or the like as carry-out means.

  Next, the carburizing method by the multistage continuous carburizing furnace 1 configured as described above will be described with reference to process explanatory diagrams shown in FIGS.

  Here, in general, the quenching in which the carburized metal material is immersed in the quenching medium completes the quenching transformation by immersing the metal material in the quenching medium for approximately 5 minutes, and the operation time required for the quenching is approximately 10 minutes. Therefore, a case where the quenching cycle is set to 10 minutes will be described as an example.

  The doors 16-1 to 16-4 on the upstream side of the multi-stage carburizing furnace 10, the doors 17-1 to 17-4 that partition the carburizing zone 11 and the diffusion zone 12, and the partitions that separate the diffusion zone 12 and the cooling zone 13 The doors 18-1 to 18-4 and the doors 19-1 to 19-4 on the downstream side of the multi-stage carburizing furnace 10 are closed, and the inside of the multi-stage carburizing furnace 10 is changed to the carburizing zone 11, the diffusion zone 12, and the cooling zone 13. Partition.

  The carburizing gas is supplied into the carburizing zone 11 in which the upstream inlet is closed by the doors 16-1 to 16-4 and the downstream side is closed by the doors 17-1 to 17-4. The temperature and atmosphere in the carburizing zone 11 are controlled to be set in advance by temperature control or the like. This control is performed by the first to fourth carburizing zones 11-1 to 11 by the first to fourth transport roller conveyors 14-1 to 14-4 that can secure the flow of the airflow including the carburizing gas. Since it is divided into 11-4, the carburizing zone extending from the first stage to the fourth stage carburizing zone 11-1 to 11-4 without being affected by the arrangement of the transport roller conveyors 14-1 to 14-4. 11 can be controlled to have a uniform temperature and atmosphere, or to a good state in which the occurrence of uneven temperature and atmosphere is extremely suppressed.

  Similarly, in the diffusion zone 12 partitioned from the carburizing zone 11 by the doors 17-1 to 17-4 closed on the upstream side and separated from the cooling zone 13 by the doors 18-1 to 18-4 closed on the downstream side. The temperature and atmosphere are controlled to a preset state. This control is divided into the first to fourth diffusion zones 12-1 to 12-4 by the first to fourth transport roller conveyors 14-1 to 14-4 that can secure the airflow. Therefore, the entire temperature in the diffusion zone 12 over the first to fourth diffusion zones 12-1 to 12-4 is not affected by the arrangement of the transport roller conveyors 14-1 to 14-4. And the atmosphere can be controlled to be in a non-uniform state, or to be in a favorable state in which the occurrence of unevenness in temperature and atmosphere is extremely suppressed.

  Further, the temperature and atmosphere in the temperature-falling zone 13 which is partitioned from the diffusion zone 12 by the doors 18-1 to 18-4 closed on the upstream side and closed by the doors 19-1 to 19-4 on the downstream side are set in advance. Control the temperature so that it is suitable for lowering the temperature. This control is divided into the first to fourth cooling zones 13-1 to 13-4 by the first to fourth carry-out roller conveyors 15-1 to 15-4 that can secure the flow of the airflow. Therefore, the entire inside of the temperature lowering zone 13 extending from the first to fourth temperature decreasing zones 13-1 to 13-4 is good without being affected by the arrangement of the carry-out roller conveyors 15-1 to 15-4. The temperature and atmosphere can be controlled.

  The carburizing zone 11, the diffusion zone 12 and the temperature lowering zone 13 of the multi-stage carburizing furnace 10 are maintained and controlled in a favorable state, and the carburizing furnace area order, for example, the first stage carburizing furnace area is maintained. Carburizing treatment is performed on each of the first to fourth carburizing zones 11-1 to 11-4 in the order of I, second carburizing furnace area II, third carburizing furnace area III, and fourth carburizing furnace area IV. The heat treatment pallet 50 on which the metal material to be mounted is loaded sequentially. Then, the metal material is carburized while the heat treatment pallet 50 loaded with the metal material is conveyed through the carburizing furnace areas I to IV for each of the first stage to the fourth stage, and the first stage to the first stage in the carburizing furnace area order. Quenching is carried out in a quenching cycle continuously carried out from the four stages of temperature lowering zones 13-1 to 13-4 and in the quenching zone 21.

  The carburizing and quenching process will be specifically described. First, when the pallet detection sensor 11-1s detects that the heat treatment pallet 50 is absent, the carburizing process carried in by the carry-in roller conveyor 29 as shown in FIG. A heat treatment pallet 50 loaded with a metal material is placed on the first-stage transport roller conveyor 14-1 in the first-stage carburizing furnace area I from the entrance where the door 16-1 is opened by the carry-in elevator 25, and the pallet. 50 is held at the first stop position 11-1a by a stopper. Thereafter, the door 16-1 is closed, and the carburization of the metal material mounted on the heat treatment pallet 50 that has been charged is started.

  After the heat treatment pallet 50 is put into the first stop position 11-1a of the first stage carburizing zone 11-1, the second stage carburizing zone 11- is detected by the pallet detection sensor 11-2s after 10 minutes corresponding to the quenching cycle. When the heat treatment pallet 50 is detected to be absent at the second first stop position 11-2a, the door 16-2 is opened by the carry-in elevator 25 for the heat treatment pallet 50 loaded with the metal material to be carburized next. Then, it is put on the second-stage transport roller conveyor 14-2 from the entrance and is held at the first stop position 11-2a. Then, the door 16-2 is closed and carburization of the charged metal material is started.

  Similarly, 10 minutes after the heat treatment pallet 50 is put into the second stage carburizing zone 11-2, heat treatment is performed at the first stop position 11-3a of the third stage carburizing zone 11-3 by the pallet detection sensor 11-3s. When it is detected that the pallet 50 is absent, the heat treatment pallet 50 loaded with the metal material to be carburized is loaded onto the third-stage transport roller conveyor 14-3 by the carry-in elevator 25, and the first stop position 11 thereof. -3a. Furthermore, 10 minutes after the heat treatment pallet 50 is put into the third stage carburization zone 11-3, the heat treatment pallet is moved to the first stop position 11-4a of the fourth stage carburization zone 11-4 by the pallet detection sensor 11-4s. When it is detected that 50 is absent, the heat treatment pallet 50 loaded with the metal material to be carburized is loaded onto the fourth-stage transport roller conveyor 14-4 by the carry-in elevator 25, and the first stop position 11- 4a.

  10 minutes after the heat treatment pallets 50 are sequentially put into the first stop positions 11-1a to 11-4a of the first stage carburizing zone 11-1 to the fourth stage carburizing zone 11-4, that is, the fourth stage carburizing zone. After 10 minutes have passed since the heat treatment pallet 50 was charged in 11-4, the holding of the heat treatment pallet 50 at the first stop position 11-1a in the first stage carburizing furnace area I which was initially charged is released, and this heat treatment pallet 50 is transported to the second stop position 11-1b by the first-stage transport roller conveyor 14-1, and held at the second stop position 11-1b. When the pallet detection sensor 11-1s detects that the heat treatment pallet 50 is not present at the first stop position 11-1a, the carry-in elevator 25 puts the heat treatment pallet 50 on the first-stage transport roller conveyor 14-1. And it hold | maintains at the 1st stop position 11-1a.

  The heat treatment pallet held at the first stop position 11-2a of the second stage carburizing zone 11-2 10 minutes after the heat treatment pallet 50 is put into the first stop position 11-1a of the first stage carburization zone 11-1. 50 is released, and the heat treatment pallet 50 is transported to the second stop position 11-2b by the second-stage transport roller conveyor 14-2 and held at the second stop position 11-2b. When the pallet detection sensor 11-2s detects that the heat treatment pallet 50 is absent at the first stop position 11-2a, the heat treatment pallet 50 is loaded onto the second-stage transport roller conveyor 14-2 by the loading elevator 25, Hold at the first stop position 11-2a.

  10 minutes after putting the heat treatment pallet 50 into the first stop position 11-2a of the second stage carburization zone 11-2, the heat treatment pallet held at the first stop position 11-3a of the third stage carburization zone 11-3. 50 is released, and the heat treatment pallet 50 is transported to the second stop position 11-3b by the third-stage transport roller conveyor 14-3 and held at the second stop position 11-3b. When the pallet detection sensor 11-3s detects that the heat treatment pallet 50 is absent at the first stop position 11-3a, the heat treatment pallet 50 is loaded onto the third-stage transport roller conveyor 14-3 by the loading elevator 25, Hold at the first stop position 11-3a.

  10 minutes after the heat treatment pallet 50 is put into the first stop position 11-3a of the third stage carburizing zone 11-3, the heat treatment pallet 50 held at the first stop position 11-4a of the fourth carburization zone 11-4. The heat treatment pallet 50 is transported to the second stop position 11-4b by the fourth-stage transport roller conveyor 14-4 and held at the second stop position 11-4b. When the pallet detection sensor 11-4s detects that the heat treatment pallet 50 is not present at the first stop position 11-4a, the carry-in elevator 25 puts the heat treatment pallet 50 onto the fourth-stage transport roller conveyor 14-4. And held at the first stop position 11-4a.

  Similarly, the pallet detection is performed while intermittently transporting the heat treatment pallet 50 put into the first stop positions 11-1a to 11-4a by the respective first to fourth transport roller conveyors 14-1 to 14-4. The presence or absence of the heat treatment pallet 50 is confirmed by the sensors 11-1s to 11-4s, and the heat treatment pallet 50 is repeatedly placed on the first to fourth transport roller conveyors 14-1 to 14-4 in the carburizing furnace area order. The

  Thereby, the heat treatment pallet 50 thrown on the 1st stage conveyance roller conveyor 14-1 stops each of the 1st-6th stop positions 11-1a-11-1f in the 1st stage carburizing zone 11-1. It is intermittently conveyed sequentially to the position. And during this conveyance, the metal material mounted on the heat treatment pallet 50 is carburized in the first stage carburizing zone 11-1, and further, the first to third stop positions 12- in the first stage diffusion zone 12-1. 1a to 12-1c are intermittently moved in order to diffuse carbon into the metal material, and then are conveyed to the first stage temperature drop zone 13-1.

  Here, the heat treatment pallet 50 is moved by the first-stage transport roller conveyor 14-1 for 40 minutes at each of the first to sixth stop positions 11-1a to 11-1f in the first carburizing zone 11-1. The carburization cycle of 240 minutes can be secured in the first carburizing zone 11-1 while being stopped. The first diffusion zone 12-1 is held for 40 minutes at each of the first to third stop positions 12-1a to 12-1f, and the first diffusion zone 12-1 is kept for 120 minutes. A diffusion cycle can be secured. The doors 16-1 to 16-4, 17-1 to 17-4, 18-1 to 18-4, 19-1 to 19-4 are opened only when passing through the heat treatment pallet 50, and are normally closed. ing.

  Similarly, the heat treatment pallets 50 put on the second to fourth transport roller conveyors 14-2 to 14-4 are respectively in the second to fourth carburizing zones 11-2 to 11-. 4 is intermittently conveyed sequentially from the first stop positions 11-2a to 11-4a to the sixth stop positions 11-2f to 11-4f. And it carburizes in each carburizing zone 11-2 to 11-4 of the 2nd stage-the 4th stage, and also each 1st stop in each diffusion zone 12-2-12-4 of the 2nd stage-the 4th stage. From the positions 12-2a to 12-4a, the stop positions of the third stop positions 12-2c to 11-4c are intermittently conveyed sequentially, and in the diffusion zones 12-2 to 12-4 of the second to fourth stages. Carbon is diffused into the metal material, and then conveyed to the temperature-lowering zones 13-2 to 13-4 in the second to fourth stages as shown in FIG.

  Here, each heat treatment pallet 50 can secure a carburizing cycle of 240 minutes in the carburizing zone 11 and can secure a diffusion cycle of 120 minutes in the diffusion zone 12.

  Further, the first to fourth stages disposed in the first to fourth cooling zones 13-1 to 13-4 from the first to fourth diffusion zones 12-1 to 12-4 side. The four-stage carry-out roller conveyors 15-1 to 15-4 have 10 intervals corresponding to the charging intervals of the heat treatment pallets 50 to the carburizing zones 11-1 to 11-4 of the first to fourth stages, that is, the quenching cycle. The heat treatment pallets 50 loaded with the carburized and diffused metal material are intermittently carried in sequentially in accordance with the carburizing furnace area order at minute intervals.

  In the first stage cooling zone 13-1, after the metal material mounted on the heat treatment pallet 50 carried into the first stage cooling zone 13-1 is gradually cooled for 40 minutes, as shown in FIG. The heat treatment pallet 50 in the first-stage cooling zone 13-1 is carried out by the first-stage carry-out roller conveyor 15-1 to the quenching elevator 27 that has risen to standby at the position 13-1. As shown in FIG. 5, the quenching elevator 27 equipped with the heat treatment pallet 50 descends and immerses the heat treatment pallet 50 in oil as a quenching medium in the quenching zone 21 to quench the metal material. After the preset immersion time has elapsed and the quenching transformation of the metal material is completed, the heat treatment pallet 50 is raised from the quenching zone 21 by the quenching elevator 27 and transferred to the carry-out roller conveyor 30 and carried out. This quenching cycle is set to 10 minutes.

  After the transfer of the heat treatment pallet 50 from the first-stage cooling zone 13-1 to the quenching elevator 27, or after the transfer, as shown in FIG. The heat treatment pallets 50 held at the first to sixth stop positions 11-1a to 11-1f of the carburizing zone 11-1 are respectively adjacent to the second stop positions 11-1b to the first stage diffusion zone 12. -1 to the first stop position 12-1a. Similarly, each heat treatment pallet 50 held in each of the first to third stop positions 12-1a to 12-1c of the first stage diffusion zone 12-1 is adjacent to the second stop position 12-1b. To the first stage temperature drop zone 13-1. After that, when the pallet detection sensor 11-1s detects that the heat treatment pallet 50 is absent at the first stop position 11-1a, the new heat treatment pallet 50 loaded with the metal material is moved to the first stage by the loading elevator 25. It is put on the transport roller conveyor 14-1 and held at the first stop position 11-1a.

  Next, in the second stage cooling zone 13-2, after quenching the metal material mounted on the heat treatment pallet 50, as shown in FIG. 7, the quenching elevator waiting at the position of the second stage cooling zone 13-2. 27, the heat treatment pallet 50 in the second stage temperature drop zone 13-2 is carried out by the second stage carry-out roller conveyor 15-2. The quenching elevator 27 equipped with the heat treatment pallet 50 descends as shown in FIG. 8 and immerses the heat treatment pallet 50 in the oil in the quenching zone 21 to quench the metal material. After the elapse of a preset immersion time, the heat treatment pallet 50 is raised from the quenching zone 21 by the quenching elevator 27, transferred to the carry-out roller conveyor 30, and carried out.

  At this time, in conjunction with or after the transfer of the heat treatment pallet 50 from the second stage cooling zone 13-2 to the quenching elevator 27, as shown in FIG. The heat treatment pallets 50 held at the first to sixth stop positions 11-2a to 11-2f of the stage carburizing zone 11-2 are respectively adjacent to the second stop positions 11-2b to the second stage diffusion zone. Each of them is sequentially conveyed to the first stop position 12-2a of 12-2. Further, each heat treatment pallet 50 held at each of the first to third stop positions 12-2a to 12-2c of the second stage diffusion zone 12-2 is adjacent to the second stop positions 12-2b to 2nd. It is sequentially conveyed to the step-down temperature zone 13-2. Thereafter, when the pallet detection sensor 11-2s detects that the heat treatment pallet 50 is absent at the first stop position 11-2a, the new heat treatment pallet 50 loaded with the metal material is moved to the second stage by the loading elevator 25. It is put on the transport roller conveyor 14-2 and held at the first stop position 11-2a.

  Similarly, after the metal material mounted on the heat treatment pallet 50 is gradually cooled in the third stage cooling zone 13-3, as shown in FIG. 9, it is used for quenching waiting at the position of the third stage cooling zone 13-3. The heat treatment pallet 50 in the third stage temperature drop zone 13-3 is carried out to the elevator 27 by the second stage carry-out roller conveyor 15-3. Thereafter, the quenching elevator 27 on which the heat treatment pallet 50 is mounted descends, and the heat treatment pallet 50 is immersed in the oil in the quenching zone 21 to quench the metal material. After elapse of a preset dipping time, the heat treatment pallet 50 is raised from the quenching zone 21 by the quenching elevator 27, transferred to the carry-out roller conveyor 30, and carried out.

  The first stage of the third stage carburizing zone 11-3 is linked to the transfer of the heat treatment pallet 50 from the third stage temperature drop zone 13-3 to the quenching elevator 27 or after the transfer by the third stage transport roller conveyor 14-3. Each heat treatment pallet 50 held at each of the sixth stop positions 11-3a to 11-3f and the first to third stop positions 12-3a to 12-3c of the third stage diffusion zone 12-3 , The second stop position 11-3b of the third stage carburizing zone 11-3 adjacent to the third stop position 12-3c of the third stage diffusion zone 12-3 and the third stage temperature drop zone 13-3, respectively. The Thereafter, as shown in FIG. 10, when the pallet detection sensor 11-3s detects that the heat treatment pallet 50 is absent at the first stop position 11-3a, a new heat treatment pallet 50 loaded with a metal material is carried in. The elevator 25 puts it on the third stage transport roller conveyor 14-3 and holds it at the first stop position 11-3a.

  Subsequently, after the metal material mounted on the heat treatment pallet 50 is gradually cooled in the fourth stage temperature drop zone 13-4, the fourth stage temperature drop is sent to the quenching elevator 25 waiting at the position of the fourth stage temperature drop zone 13-4. The heat treatment pallet 50 in the zone 13-4 is unloaded by the fourth-stage unloading roller conveyor 15-4. Then, the quenching elevator 27 descends and the heat treatment pallet 50 is immersed in the oil in the quenching zone 21 to quench the metal material, and after the preset soaking time has elapsed, the quenching elevator 27 performs heat treatment from the quenching zone 21. The pallet 50 is raised, transferred to the carry-out roller conveyor 30 and carried out.

  The first stage of the fourth stage carburizing zone 11-4 is linked to the transfer of the heat treatment pallet 50 from the fourth stage temperature drop zone 13-4 to the quenching elevator 27 or after the transfer by the fourth stage transport roller conveyor 14-4. The heat treatment pallets 50 held at the sixth stop positions 11-4a to 11-4f and the first to third stop positions 12-4a to 12-4c of the fourth stage diffusion zone 12-4 These are sequentially conveyed to the second stop position 11-4b of the adjacent fourth carburizing zone 11-4 to the third stop position 12-4c of the fourth stage diffusion zone 12-4 and the fourth stage temperature decreasing zone 13-4, respectively. . Thereafter, when the pallet detection sensor 11-4s detects that the heat treatment pallet 50 is absent at the first stop position 11-4a, the new heat treatment pallet 50 loaded with the metal material is moved to the fourth stage by the loading elevator 25. It is put on the transport roller conveyor 14-4 and held at the first stop position 11-4a.

  Thus, the heat treatment pallet in which the metal materials are sequentially mounted in the carburizing furnace area order in the carburizing zones 11-1 to 11-4 of the first stage to the fourth stage of the multi-stage carburizing furnace 10 at intervals according to the quenching cycle. 50, while the heat treatment pallet 50 moves in the carburizing zones 11-1 to 11-4 of the first to fourth stages and the diffusion zones 12-1 to 12-4 of the first to fourth stages. In addition, carburization and carbon diffusion are continuously performed, and are sequentially transported to the first to fourth cooling zones 13-1 to 13-4 and gradually cooled. Then, the heat treatment pallet 50 on which the metal material slowly cooled in each of the first to fourth temperature lowering zones 13-1 to 13-4 is mounted in the quenching zone 21 by the quenching elevator 27 in order according to the carburizing furnace area order. A series of carburizing and quenching processes in which the metal material is quenched by immersion in oil are continuously performed.

  Therefore, each of the first to fourth transport roller conveyors 14-1 capable of ensuring the flow of the airflow in the carburizing zone 11 and the diffusion zone 12 in the continuous carburizing furnace 10 according to the present embodiment configured as described above. Are divided into the carburizing zones 11-1 to 11-4 of the first stage to the fourth stage and the diffusion zones 12-1 to 12-4 of the first stage to the fourth stage. The first to fourth carburizing zones 11-1 to 11- are not affected by the first to fourth transport roller conveyors 14-1 to 14-4. The overall temperature and atmosphere in the carburizing zone 11 over 4 can be controlled to be in a good state. Similarly, the overall temperature in the diffusion zone 12 over the diffusion zones 12-1 to 12-4 in the first to fourth stages The atmosphere can be controlled well.

  The first to fourth carburizing zones 11-1 to 11-4 and the first to fourth diffusion zones 12-1 to 12-4, which are maintained in a good state, are loaded with a metal material. Since the heat treatment pallets 50 are transported by the first to fourth transport roller conveyors 14-1 to 14-4 in a stacked state one by one without stacking, the first to fourth stages The atmosphere such as the flow of carburizing gas and the carburizing temperature in each carburizing zone 11-1 to 11-4 can be kept constant, and each heat treatment is performed in each carburizing zone 11-1 to 11-4 in the first to fourth stages. The variation in the amount of carbon entering the metal surface mounted on the pallet 50 is small, and the temperature and atmosphere in the first to fourth diffusion zones 12-1 to 12-4 are kept constant, so that the first stage ~ Each heat treatment pallet in the fourth stage diffusion zones 12-1 to 12-4 0 good carburizing no variation in the diffusion of carbon into the interior of the mounting metal material is obtained by efficiently continuously in parallel.

  Furthermore, the single heat treatment pallet 50 is put into the oil without stacking the heat treatment pallets 50 loaded with the metal material gradually cooled in the first to fourth temperature drop zones 13-1 to 13-4. Thus, there is no difference in the cooling transformation between the metal materials placed on the respective heat treatment pallets 50 without any deviation in the timing of charging into the oil, and there is no difference in the progress of the quenching transformation. Further, variation in deformation caused by quenching between the metal materials is suppressed, the dimensional accuracy of the metal material after treatment is stabilized, and a high-quality carburizing quenching process can be ensured.

  Further, according to the carburizing furnace area order set in advance at intervals corresponding to the quenching cycle, the first stage to the fourth stage carburizing zones 11-1 to 11-4 and the first stage to the fourth stage diffusion zone 12- 1 to 12-4, a heat treatment pallet 50 loaded with a metal material is charged, and the first to fourth carburizing zones 11-1 to 11-4 and the first to fourth diffusion zones 12 are placed. Carburizing process is performed in parallel in -1 to 12-4, and after quenching in each of the first to fourth cooling zones 13-1 to 13-4, quenching is performed in a continuous quenching cycle without interruption. And carburizing and quenching with excellent productivity can be obtained.

  Further, the carburizing zone 11 and the diffusion zone 12 in the continuous carburizing furnace 10 are partitioned by the first to fourth transport roller conveyors 14-1 to 14-4 and the first carburizing area I, second The stage carburizing area II, the third stage carburizing area III, and the fourth stage carburizing area IV are formed in a multi-stage shape, and the carry-in elevator 25 is disposed upstream of the continuous carburizing furnace 10 and the quenching elevator 27 is disposed downstream. Thereby, the length of the width direction of the multistage continuous carburizing furnace 1 can be suppressed, and reduction of the installation place can be expected.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of invention. For example, in the above embodiment, the first-stage carburizing zone 11-1 to the second-stage, third-stage, and fourth-stage carburizing zones 11-2, 11-3, and 11-4 according to the preset carburizing furnace area order. In this order, the heat treatment pallet 50 is loaded from the carry-in elevator 25, and the first, second, third, and fourth temperature drop zones 13-2, 13-3, and 13-4 from the first temperature drop zone 13-1. The heat treatment pallet 50 was carried out in order to the quenching elevator 27 and subjected to quenching treatment in sequence, but the heat treatment pallet was placed in the first to fourth carburizing zones 11-1 to 11-4 according to the order of other carburizing furnace areas. 50 can also be input. In this case, the order of carrying out from the first to fourth temperature drop zones 13-1 to 13-4 to the quenching elevator 27 is also changed in accordance with the charging order.

  Moreover, in the said embodiment, although the conveying apparatus of the 1st stage-the 4th stage was formed with the roller conveyor, it can also be formed with other types of conveying apparatuses which allow passage of airflows, such as a tact conveyor.

  Furthermore, in the above embodiment, the case where the first to fourth stages of the four-stage carburized areas I to IV have been described, but a plurality of stages of carburized areas such as two stages, three stages, or five stages are formed. You can also.

It is an outline explanatory view of a multi-stage continuous carburizing furnace which shows an outline of an embodiment of a multi-stage continuous carburizing furnace and a continuous carburizing method concerning the present invention. It is process explanatory drawing of the carburizing method by a multistage continuous carburizing furnace. It is process explanatory drawing of the carburizing method by a multistage continuous carburizing furnace. It is process explanatory drawing of the carburizing method by a multistage continuous carburizing furnace. It is process explanatory drawing of the carburizing method by a multistage continuous carburizing furnace. It is process explanatory drawing of the carburizing method by a multistage continuous carburizing furnace. It is process explanatory drawing of the carburizing method by a multistage continuous carburizing furnace. It is process explanatory drawing of the carburizing method by a multistage continuous carburizing furnace. It is process explanatory drawing of the carburizing method by a multistage continuous carburizing furnace. It is process explanatory drawing of the carburizing method by a multistage continuous carburizing furnace. It is explanatory drawing of the conventional multistage continuous carburizing furnace.

Explanation of symbols

1 multi-stage continuous carburizing furnace 10 multi-stage carburizing furnace I first stage carburizing furnace area II second stage carburizing furnace area III third stage carburizing furnace area IV fourth stage carburizing furnace area 11 carburizing zones 11-1 to 11-4 first stage -4th stage carburizing zone 12 Diffusion zones 12-1-12-4 1st stage-4th stage diffusion zones 13 Temperature reduction zones 13-1-13-4 1st stage-4th stage temperature reduction zones 14-1-14- 4 1st to 4th transport roller conveyors (1st to 4th transport devices)
15-1 to 15-4 First-stage to fourth-stage carry-out roller conveyors (first-stage to fourth-stage conveyance devices)
16-1 to 19-4 Door (open / close partition means)
21 Quenching zone 25 Elevator for loading (work input means)
27 Elevator for quenching 29 Carry-in roller conveyor 30 Carry-out roller conveyor 50 Heat treatment pallet

Claims (6)

Carburizing treatment for carrying out carburizing to the surface of the metal material and carbon diffusion to the inside of the metal material by sequentially transporting in the carburizing zone, the diffusion zone and the cooling zone in the furnace, and the carburized metal material in the quenching zone In a continuous carburizing and quenching furnace that continuously performs a quenching process by immersing in a quenching medium and quenching,
A plurality of carburizing zones, diffusion zones, and temperature-lowering zones are arranged in order from the upstream side to the downstream side in the furnace, and the furnace is divided into multi-stage carburizing furnace areas that continue from the carburizing zone to the temperature-falling zone, respectively. A multi-stage carburizing furnace having a transfer device of
A heat treatment pallet mounted on the upstream side of the multi-stage carburizing furnace and mounted with a metal material to be carburized and quenched on the upstream side of the transfer device in the carburizing furnace area at an interval corresponding to a quenching cycle according to a predetermined carburizing furnace area order A workpiece input device that sequentially inputs
Mounted on the downstream side of the multi-stage carburizing furnace is loaded with a carburized metal material that is loaded into each carburizing furnace zone by the work feeding device and transported to the cooling zone through the carburizing zone and diffusion zone by the transporting device. A quenching zone in which the heat treatment pallet is immersed in a quenching medium in a sequential quenching cycle from the temperature lowering zone of each carburizing furnace area in accordance with the set carburizing furnace area order and quenching the metal material. A multi-stage continuous carburizing and quenching furnace.   The multistage continuous carburizing and quenching furnace according to claim 1, wherein the transfer device that divides the carburizing furnace zones allows airflow between the carburizing furnace areas.   The multistage continuous carburizing and quenching furnace according to claim 2, wherein the conveying device is a roller conveyor. The upstream end of each carburizing furnace area, between the carburizing zone and the diffusion zone, between the diffusion zone and the cooling zone, and opened when the heat treatment pallet loaded with the metal material passes through the part. multistage continuous carburizing and quenching furnace according to claim 1, characterized in that it comprises a plurality of closing partitioning means for allowing the movement. In the quenching zone,
The heat treatment pallet is disposed on the downstream side equipped with carburized metallic material is carried from the temperature lowering zone of each of the carburizing furnace areas in accordance with the carburizing furnace areas order that is the setting of the multistage carburizing furnace and immersed in the quenching medium while quenching the metallic material Te, multistage continuous carburizing and quenching according to any one of claims 1 to 4, comprising the quenching elevator for unloading the heat treatment pallets equipped quenching treated metal material Furnace.

Carburizing treatment for carrying out carburizing on the surface of the metal material and carbon diffusion into the inside of the metal material by sequentially transporting in the carburizing zone, diffusion zone and temperature lowering zone in the furnace, and the carburized metal material in the quenching medium In the continuous carburizing and quenching method in which the quenching treatment to be immersed is continuously performed,
A plurality of carburizing zones, diffusion zones, and temperature-lowering zones are arranged in order from the upstream side to the downstream side in the furnace, and the furnace is divided into multi-stage carburizing furnace areas that continue from the carburizing zone to the temperature-falling zone. A multi-stage carburizing furnace having a transfer device,
In accordance with a preset carburizing furnace area order, heat treatment pallets loaded with metal materials to be carburized and quenched are sequentially placed on the upstream side of the transfer device in the carburizing furnace area at intervals corresponding to the quenching cycle, and each carburizing furnace zone is individually loaded. The heat treatment pallet loaded with the metal material that has been charged and transferred to the temperature lowering zone through the carburizing zone and diffusion zone by the transfer device and loaded with the carburized metal is placed in the temperature lowering zone of each carburizing furnace area according to the carburizing furnace area order set above. A continuous carburizing and quenching method, wherein the metal material is immersed in a quenching medium in a continuous quenching cycle.

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