Gas carburizing apparatus and carburizing chamber

Abstract

To provide a gas carburizing apparatus that enables treatment of a subsequent workpiece to be carried out while a preceding workpiece is under processing.SOLUTION: The present invention includes a pre-chamber in which a workpiece is temporarily placed, a carburizing chamber arranged downstream in a workpiece conveying direction from the pre-chamber and configured to supply a carburizing gas and heat the workpiece under atmospheric pressure, a quenching chamber arranged downstream of the carburizing chamber in the conveying direction and configured to perform quenching treatment on the workpiece, a carburizing chamber transfer device that transfers the workpiece from the pre-chamber to the carburizing chamber, a workpiece moving mechanism that moves the workpiece in the carburizing chamber in the conveying direction, a quenching chamber transfer device that transfers the carburized workpiece from the carburizing chamber to the quenching chamber, and a raw gas supply device that supplies a carrier gas and a carburizing gas to the carburizing chamber, wherein in the carburizing chamber a plurality of workpieces are configured to be arranged in a row in the conveying direction, and the workpiece moving mechanism collectively moves the workpieces arranged in a row in the carburizing chamber in the conveying direction each time a workpiece is transferred from the pre-chamber to the carburizing chamber by the carburizing chamber transfer device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a gas carburizing apparatus and a carburizing chamber. [Background technology]

[0002] Carburizing has traditionally been performed to harden the surface layer of metals such as steel. Gas carburizing equipment for carburizing has been proposed, for example, that includes an outer region, an antechamber, an oil tank located below the antechamber, and a carburizing chamber located further back in the transport path than the antechamber (see, for example, Patent Document 1). In this gas carburizing equipment, the workpiece to be carburized is transported in the following order: outer region, antechamber, carburizing chamber, antechamber, oil tank, and outer region. During this process, carburizing is performed in the carburizing chamber, followed by quenching in the antechamber and oil tank. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Application No. 2023-066198 Summary of the Invention [Problem to be solved by the invention]

[0004] In the gas carburizing apparatus of Patent Document 1, a series of processes such as carburizing and quenching for a preceding workpiece cannot be carried out on the next workpiece until the series of processes is completed.

[0005] In view of the above circumstances, the present invention aims to provide a gas carburizing apparatus and a carburizing chamber that can process a next workpiece while the previous workpiece is being processed. [Means for solving the problem]

[0006] a quenching chamber located downstream of the carburizing chamber in the direction of transport of the workpiece and in which carburizing gas is supplied and the workpiece is heated at atmospheric pressure or a higher pressure than atmospheric pressure to carburize the workpiece; a carburizing chamber transport device for moving the workpiece from the carburizing chamber to the carburizing chamber; a work moving mechanism for moving the workpiece within the carburizing chamber in the direction of transport; a quenching chamber transport device for moving the carburized workpiece from the carburizing chamber to the quenching chamber; and a raw material gas supply device for supplying to the carburizing chamber a carrier gas and the carburizing gas containing acyclic unsaturated hydrocarbons that are more easily adsorbed by the workpiece than the carrier gas, wherein the carburizing chamber is configured so that multiple workpieces can be arranged in a row in the direction of transport, and the work moving mechanism moves the workpieces that are lined up consecutively in a row in the carburizing chamber together in the direction of transport each time the carburizing chamber transport device moves a workpiece from the

[0007] The gas carburizing apparatus of the present invention further comprises a workpiece unloading area located downstream of the quenching chamber in the transfer direction; a unloading device that moves the quenched workpiece from the quenching chamber to the workpiece unloading area; a front chamber negative pressure generating device that draws in the internal gas of the front chamber to create a negative pressure; a purge gas supply device that supplies purge gas to the front chamber, which has been placed in a negative pressure state, to restore the pressure in the front chamber to normal pressure or a pressure higher than normal pressure; a quenching chamber negative pressure generating device that draws in the internal gas of the quenching chamber to create a negative pressure; and a quenching chamber purge gas supply device that supplies purge gas to the quenching chamber, which has been placed in a negative pressure state, to restore the pressure in the quenching chamber to normal pressure or a pressure higher than normal pressure.

[0008] In the gas carburizing apparatus of the present invention, the carburizing chamber has, from upstream to downstream, a temperature rise section for performing temperature rise treatment on workpieces transported from the antechamber to a preset carburizing temperature, a carburizing section for supplying the carrier gas and carburizing gas to the workpieces that have passed through the temperature rise section, and a diffusion section for performing diffusion treatment to diffuse carbon that has penetrated the workpieces that have passed through the carburizing section and form a hardened layer of the desired thickness on the workpieces, and is characterized in that workpieces can be placed simultaneously in the temperature rise section, carburizing section, and diffusion section.

[0009] In the gas carburizing apparatus of the present invention, the carburizing chamber has exhaust paths for exhausting gas inside the carburizing chamber upstream and downstream of the carburizing zone, and the exhaust of gas through the exhaust paths causes the carrier gas supplied to the carburizing zone and the residual gas remaining after carburizing the workpiece with the carburizing gas to flow into the temperature rise zone and the diffusion zone.

[0010] In the gas carburizing apparatus of the present invention, the carburizing chamber has a temperature-reducing section for performing a temperature-reducing process to reduce the temperature of the workpiece that has passed through the diffusion section to a preset quenching holding temperature, and is characterized in that workpieces can be placed simultaneously in the temperature-rising section, the carburizing section, the diffusion section, and the temperature-reducing section.

[0011] In the gas carburizing apparatus of the present invention, the carrier gas contains nitrogen, and the chain unsaturated hydrocarbon contains acetylene.

[0012] In the gas carburizing apparatus of the present invention, the concentration of the acetylene contained in the atmosphere in the carburizing chamber is 0.25% by volume or less.

[0013] In the gas carburizing apparatus of the present invention, the concentration of the acetylene contained in the atmosphere in the carburizing chamber is 0.10% by volume or more.

[0014] In the gas carburizing apparatus of the present invention, the workpiece moving mechanism comprises a transport path for transporting a plurality of workpieces (hereinafter referred to as the row of preceding workpieces) lined up in a row in the carburizing chamber, and the carburizing chamber transport device, and each time a workpiece (hereinafter referred to as the subsequent workpiece) is moved from the anterior chamber to the carburizing chamber by the carburizing chamber transport device, the subsequent workpiece pushes the row of preceding workpieces in the transport direction, causing them to move in the transport direction.

[0015] In the gas carburizing apparatus of the present invention, each workpiece in the row of preceding workpieces is placed at a preset standby position, and the workpiece moving mechanism is configured to move each workpiece in the row of preceding workpieces to the adjacent standby position downstream in the transport direction each time the carburizing chamber transport device moves the subsequent workpiece from the antechamber to the carburizing chamber, and the carburizing chamber has, from upstream to downstream, a temperature rise section for performing a temperature rise treatment on the workpieces transported from the antechamber to a preset carburizing temperature, a carburizing section for supplying the carrier gas and carburizing gas to the workpieces that have passed through the temperature rise section, and a diffusion section for performing a diffusion treatment to diffuse carbon that has penetrated the workpieces that have passed through the carburizing section and form a hardened layer of a desired thickness on the workpieces, and the temperature rise section includes a first number of standby positions, the carburizing section includes a second number of standby positions, and the diffusion section includes a third number of standby positions.

[0016] In the gas carburizing apparatus of the present invention, the second number is larger than the first number.

[0017] In the gas carburizing apparatus of the present invention, when the time from when the previous workpiece is moved from the pre-chamber to the carburizing chamber by the carburizing chamber transfer device to when the next workpiece is moved from the pre-chamber to the carburizing chamber is defined as a reference time, the time during which the temperature rise treatment of the workpiece in the temperature rise section is defined as a temperature rise time, the time during which the carrier gas and carburizing gas are supplied to the workpiece in the carburizing section is defined as a carburizing time, and the time during which the diffusion treatment of the workpiece in the diffusion section is defined as a diffusion time, the first number is expressed as a ratio of the temperature rise time based on the reference time, the second number is expressed as a ratio of the carburizing time based on the reference time, and the third number is expressed as a ratio of the diffusion time based on the reference time.

[0018] In the gas carburizing apparatus of the present invention, the carburizing chamber has a temperature-reducing section for performing a temperature-reducing process to reduce the temperature of the workpiece that has passed through the diffusion section to a preset quenching holding temperature, and the temperature-reducing section includes a fourth number of the standby positions.

[0019] In the gas carburizing apparatus of the present invention, the quenching chamber transport device is characterized in that it moves the carburized workpiece lined up at the front of the line of carburizing chambers to the quenching chamber every time the carburizing chamber transport device moves a workpiece from the antechamber to the carburizing chamber.

[0020] The carburizing chamber of the present invention is a carburizing chamber that is located downstream in the direction of workpiece transport of an antechamber in which the workpiece is temporarily placed, and upstream in the direction of transport of a quenching chamber in which the workpiece is quenched, and that heats the workpiece at atmospheric pressure or a pressure higher than atmospheric pressure to carburize the workpiece. It has within it, from upstream to downstream in the direction of transport, a temperature rise section for heating the workpiece transported from the antechamber to a preset carburizing temperature, a carburizing section for carrying out a carburizing gas supply process in which a carrier gas and carburizing gas are supplied to the workpiece that has passed through the temperature rise section, and a diffusion section for carrying out a diffusion process in which carbon that has penetrated the workpiece that has passed through the carburizing section is diffused to form a hardened layer of a desired thickness on the workpiece. Workpieces can be placed simultaneously in each of the temperature rise section, carburizing section, and diffusion section, and nozzles for supplying the carrier gas and carburizing gas are located in the carburizing section.

[0021] The carburizing chamber of the present invention is characterized in that it has exhaust passages upstream and downstream of the carburizing zone for exhausting gas inside the carburizing chamber (inside the carburizing chamber itself), and by exhausting the gas through the exhaust passages, residual gas remaining after carburizing the workpiece with the carburizing gas supplied to the carburizing zone flows into the temperature rise zone and the diffusion zone. [Effects of the Invention]

[0022] The gas carburizing apparatus and carburizing chamber of the present invention have the excellent effect of allowing the next workpiece to be processed even while the previous workpiece is being processed. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 2 is a diagram showing the exterior region and an antechamber of a gas carburizing apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the front chamber and subsequent sections of the gas carburizing apparatus. [Figure 3] (A) and (B) are time charts of the carburizing process using the gas carburizing equipment. [Figure 4]3(A) to 3(C) are block diagrams showing the internal configuration of a control device of the gas carburizing apparatus. [Figure 5] (A) and (B) are diagrams showing in chronological order the operation of the gas carburizing equipment and the transport of the workpiece carrier to the front chamber. [Figure 6] (A) and (B) are diagrams showing in chronological order the operation of the gas carburizing equipment, with the workpiece carrier being transported from the antechamber to the carburizing chamber. Note that (B) omits the carburizing gas system 90, carrier gas system 92, and carburizing section supply system 94, but the configuration is the same as (A). [Figure 7] (A) and (B) are diagrams showing in chronological order the operation of the gas carburizing equipment, with the subsequent workpiece carrier being transported from the antechamber to the carburizing chamber. Note that (B) omits the carburizing gas system 90, carrier gas system 92, and carburizing section supply system 94, but the configuration is the same as (A). [Figure 8] (A) is a diagram showing the state when the gas carburizing equipment is operating and the first work carrier in the line of carburizing chambers has arrived at the carburizing section. (B) is a diagram showing the state when the gas carburizing equipment is operating and the first work carrier in the line of carburizing chambers has arrived at the diffusion section. Note that (B) omits the carburizing gas system 90, carrier gas system 92, and carburizing section supply system 94, but the configuration is the same as (A). [Figure 9] (A) is a diagram showing the state when the gas carburizing equipment is operating and the first work carrier in the line of carburizing chambers has arrived at the temperature-reducing section. (B) is a diagram showing the state when the gas carburizing equipment is operating and the first work carrier in the line of carburizing chambers has passed through the temperature-reducing section and arrived at the quenching chamber. Note that (B) omits the carburizing gas system 90, carrier gas system 92, and carburizing section supply system 94, but has the same configuration as (A). [Figure 10] (A) is a diagram showing the state in which the gas carburizing equipment is operating and performing the main quenching chamber purging process in the quenching chamber. (B) is a diagram showing the state in which the workpiece carrier has been carried into the quenching chamber. Note that in this diagram, the carburizing gas system 90, carrier gas system 92, and carburizing section supply system 94 are omitted, but the configuration is the same as in Figure 2. [Figure 11] (A) and (B) are diagrams showing in chronological order the operation of the gas carburizing equipment and the workpiece carrier undergoing quenching in the quenching chamber. Note that in these diagrams, the carburizing gas system 90, carrier gas system 92, and carburizing section supply system 94 are omitted, but the configuration is the same as in Figure 2. [Figure 12] This figure shows the gas carburizing equipment in operation, with the workpiece carrier in the quenching chamber undergoing oil removal and main purging. Note that the carburizing gas system 90, carrier gas system 92, and carburizing section supply system 94 are omitted in this figure, but the configuration is the same as in Figure 2. [Figure 13] (A) and (B) are diagrams showing in chronological order the operation of the gas carburizing equipment, with a workpiece carrier being transported from the quenching chamber to the workpiece transport area, while the following workpiece carrier moves into the quenching chamber. Note that in these diagrams, the carburizing gas system 90, carrier gas system 92, carburizing section supply system 94, etc. are omitted, but the configuration is the same as in Figure 2. [Figure 14] (A) is a table showing the surface hardness results of the carburized and quenched experimental workpieces, and (B) are high- and low-magnification photomicrographs of the cross section of the carburized and quenched experimental workpieces. [Figure 15] FIG. 10 is a view showing the outer region and an antechamber of a gas carburizing apparatus according to a modified embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The accompanying drawings are an example of an embodiment of the present invention, and in the drawings, parts with the same reference numerals represent the same objects. Furthermore, the shapes and dimensional ratios of each part in each drawing are not necessarily accurate.

[0025] <Overall structure> 1 and 2, the gas carburizing apparatus in this embodiment of the present invention is used to carburize a workpiece W. The gas carburizing apparatus in this embodiment includes an outer region 1, a front chamber 2, a first connecting path 5A, a carburizing chamber 3, a second connecting path 5B, a quenching chamber 4, a workpiece unloading region 6, a front chamber transport device 70, a carburizing chamber transport device 71, a workpiece moving mechanism 72, a quenching chamber transport device 73, a carry-out device 74, a front chamber negative pressure generating device 80, a quenching chamber negative pressure generating device 87, a front chamber purge gas supply device 84, a quenching chamber purge gas supply device 89, and a raw material gas supply device 9.

[0026] The outer region 1, front chamber 2, first connecting path 5A, carburizing chamber 3, second connecting path 5B, quenching chamber 4, and workpiece unloading region 6 are arranged in this order along the transport direction of the workpiece W. In other words, the workpiece W is transported in the order of the outer region 1, front chamber 2, first connecting path 5A, carburizing chamber 3, second connecting path 5B, quenching chamber 4, and workpiece unloading region 6.

[0027] As shown in Figures 1(A) and 2, the transport direction H1 of the work W from the external area 1 to the front chamber 2 and the transport direction H2 from the front chamber 2 to the work unloading area 6 are configured to be perpendicular to each other, but this is not limited to this.

[0028] Note that, as an example, the workpieces W are made of steel such as low carbon steel or low alloy steel (e.g., SCM415, SCM420, SCr415, SCr420), but are not limited thereto and may be made of other materials. Furthermore, the workpieces W may be transported arranged vertically and horizontally on a single-stage or multi-stage platform T (see FIG. 1(B)), or may be directly placed on a transport tray C and transported. Furthermore, as shown in FIG. 1(B), the platform T may be placed on the transport tray C and transported. In this embodiment, it is described that multiple workpieces W are accommodated on the platform T, and the platform T is placed on the transport tray C and transported. Hereinafter, for convenience of explanation, the platform T placed on the transport tray C will be referred to as a workpiece carrier Tc.

[0029] <External area> A front chamber transport device 70 is disposed in the external area 1. The front chamber transport device 70 transports the work carrier Tc into the front chamber 2 in the external area 1 via the front chamber entrance 20A. The front chamber transport device 70 may be any device capable of transporting the work carrier Tc in the transport direction H1, and may be configured, for example, by a conveyor device such as a snake chain transport or a self-propelled roller conveyor that is driven by a drive source and transports the work carrier Tc in the transport direction H1. However, the present invention is not limited to this and may be configured by a transport device of another type.

[0030] As shown in FIG. 1, an example of a conveying device including a snake chain includes a roller conveyor 70A that guides the work carrier Tc into the front chamber 2, a hook 70B that grips the engagement portion Cx of the work carrier Tc, a snake chain 70C that moves the hook 70B back and forth toward the front chamber 2, and a drive source 70D that drives the snake chain 70C via a sprocket. Note that, although a structure in which the engagement portion Cx is gripped by the hook 70B is exemplified here, because the conveying is in one direction, a conveying structure in which the tip of the snake chain 70C simply pushes the side of the work carrier Tc may also be used. However, the conveying device is not limited to this, and may be configured with a conveying device of another type.

[0031] The work carrier Tc is transported to a predetermined placement area of ​​the anterior chamber 2 by the anterior chamber transport device 70. When the work carrier Tc is placed in the placement area, the work carrier Tc is installed on the transport path 27 in a state where it can be guided in the transport direction H2. The transport path 27 may be provided with a guide rail (not shown) that guides the work carrier Tc (workpiece W) in the transport direction H2.

[0032] Furthermore, when the front chamber 2 is configured to be able to receive a plurality of work carriers Tc, the front chamber transport device 70 may transport the plurality of work carriers Tc to the front chamber 2 simultaneously or sequentially one by one.

[0033] <Front room> The anterior chamber 2 is formed of an airtight and / or pressure-resistant metal container. The anterior chamber 2 temporarily accommodates the carried-in work carrier Tc (workpiece W). A transport path 27 is provided in the anterior chamber 2 for transporting the workpiece carrier Tc (workpiece W) in the transport direction H2. The workpiece carrier Tc is guided to the carburizing chamber 3 via the first connecting path 5A by guide rails provided on the transport path 27. The transport paths 27 are also provided in the first connecting path 5A, the carburizing chamber 3, the second connecting path 5B, the quenching chamber 4, and the workpiece unloading area 6.

[0034] 1(A), a front chamber entrance 20A serving as an opening is formed at the upstream end (boundary with the external area 1) in the conveying direction H1 of the front chamber 2. An openable front chamber entrance door 22 is disposed at this front chamber entrance 20A. The front chamber entrance door 22 closes the front chamber entrance 20A, thereby making the front chamber entrance 20A airtight (a state in which gas does not flow).

[0035] As shown in FIGS. 1A and 2, an opening, a front chamber outlet 20B, is formed at the downstream end of the front chamber 2 in the conveying direction H2 (at the boundary with the first connecting path 5A). A front chamber outlet door 24 that can be opened and closed is disposed at this front chamber outlet 20B. The front chamber outlet door 24 closes the front chamber outlet 20B, thereby making the front chamber outlet 20B airtight (a state in which gas does not flow). In FIG. 1A, the front chamber outlet door 24 is in an open state.

[0036] When the front room entrance door 22 and the front room exit door 24 are closed, the entire front room 2 becomes an airtight space.

[0037] <Front room entrance door> The front chamber entrance door 22 is a so-called vacuum door, and is opened and closed by a reciprocating drive mechanism 23 such as an air cylinder. Although not specifically shown, it is preferable to employ a pressing structure (for example, a parallel link structure or a slide mechanism) that presses the front chamber entrance door 22 against the front chamber entrance 20A when the front chamber entrance door 22 closes the front chamber entrance 20A by the reciprocating drive mechanism 23, thereby enhancing the airtight state.

[0038] <Exit door to the front room> The front chamber exit door 24 is a so-called vacuum door, and is opened and closed by a reciprocating drive mechanism 25 such as an air cylinder. Although not particularly shown, it is preferable to employ a pressing structure (for example, a parallel link structure or a slide mechanism) that presses the front chamber exit door 24 against the front chamber exit 20B when the front chamber exit door 24 closes the front chamber exit 20B by the reciprocating drive mechanism 25, thereby enhancing the airtight state.

[0039] <First Connection> As shown in FIG. 2, a tunnel-shaped first connecting path 5A is arranged between the front chamber 2 and the carburizing chamber 3. An opening, a front chamber outlet 20B, is formed on the front chamber 2 side of the first connecting path 5A (upstream side in the transport direction H2). The first connecting path 5A connects the front chamber 2 and the carburizing chamber 3 in an airtight manner so that gas does not enter from the external space. As already explained, a transport path 27 is also provided within the first connecting path 5A along the transport direction H2. The guide rails of the transport path 27 guide the workpiece carrier Tc transported via the first connecting path 5A to the carburizing chamber 3.

[0040] <Negative pressure generating device> The anterior chamber negative pressure generating device 80 creates a negative pressure state in the anterior chamber 2. As shown in FIG. 2, the anterior chamber negative pressure generating device 80 specifically includes a vacuum pump (negative pressure generating source) 81, a degassing flow path 82, and an on-off valve 83. The degassing flow path 82 connects the anterior chamber 2 to the vacuum pump 81. The vacuum pump 81 sucks (degasses) the gas in the anterior chamber 2, thereby creating a negative pressure state in the anterior chamber 2. Although not specifically shown, a filter or the like that adsorbs oil contained in the exhaust gas may be provided in the exhaust path beyond the vacuum pump 81. An electromagnetic on-off valve 83 is provided in the degassing flow path 82 and is opened during degassing.

[0041] <Pre-chamber purge gas supply device> A front chamber purge gas supply device 84 is connected to the front chamber 2. As shown in FIG. 2, the front chamber purge gas supply device 84 has a purge flow path 85, one end of which is connected to a purge gas source (here, the same nitrogen supply source 98 as the carrier gas is also used) and the other end of which is connected to the front chamber 2. An on-off valve 86 is disposed midway along the purge flow path 85. The on-off valve 86 is configured as an electromagnetic valve. The front chamber purge gas supply device 84 supplies a purge gas (here, nitrogen gas) to the front chamber 2, which has been degassed and placed in a negative pressure state by the front chamber negative pressure generating device 80, and this purge gas restores the front chamber 2 to normal pressure or a state higher than normal pressure (this is defined as a "pressure restored state").

[0042] <Carburizing chamber transport device> The carburizing chamber transfer device 71 transfers the workpiece carrier Tc to the carburizing chamber 3. As shown in FIG. 2, the carburizing chamber transfer device 71 is specifically composed of a pressing device 71A that can press the workpiece carrier Tc placed on the transfer path 27 of the front chamber 2 from the upstream side to the downstream side in the transfer direction H2. The pressing device 71A is composed of a reciprocating drive device that can reciprocate a piston rod 71B in the transfer direction H2, such as a hydraulic cylinder. When the piston rod 71B of this pressing device 71A presses the workpiece carrier Tc placed in the front chamber 2 in the transfer direction H2, the workpiece carrier Tc moves to the carburizing chamber 3 via the front chamber outlet 20B, the first connecting path 5A, and the carburizing chamber entrance 30A while being guided by the guide rails of the transfer path 27.

[0043] <Workpiece moving mechanism> The workpiece moving mechanism 72 moves the workpiece carrier Tc (workpiece W) inside the carburizing chamber 3A in the transfer direction H2. In this embodiment, the workpiece moving mechanism 72 moves the workpiece carriers Tc (workpiece W) lined up in a row along the transfer direction H2 in the carburizing chamber 3 in the transfer direction H2 each time the carburizing chamber transfer device 71 moves the workpiece carrier Tc (workpiece W) from the antechamber 2 to the carburizing chamber 3. The workpiece carriers Tc (workpieces W) lined up in a row along the transfer direction H2 in the carburizing chamber 3 are referred to as the preceding workpiece carrier row (preceding workpiece row) as appropriate. In this embodiment, the workpiece moving mechanism 72 is composed of the transfer path 27 extending in the transfer direction H2 inside the carburizing chamber 3A, and the carburizing chamber transfer device 71 (pressing device 71A).

[0044] On the transport path 27 inside the carburizing chamber 3A, multiple work carriers Tc (workpieces W) are lined up in a row along the transport direction H2. For this reason, when the carburizing chamber transport device 71 (pressing device 71A) moves the work carrier Tc (subsequent work carrier) from the anterior chamber 2 to the carburizing chamber 3, the subsequent work carrier Tc approaches the last work carrier Tc in the row of preceding work carriers (row of preceding works) arranged on the transport path 27. Then, the subsequent work carrier Tc pushes the entire row of preceding work carriers (row of preceding works) in the transport direction H2 through the last work carrier Tc. As a result, the entire row of preceding work carriers (row of preceding works) moves in the transport direction H2 together with the subsequent work carrier Tc.

[0045] Unlike the above, a carburizing chamber transfer device (first carburizing chamber transfer device) 71 may be used to move the subsequent work carrier Tc in the front chamber 2 in the transfer direction H2, and a carburizing chamber transfer device (second carburizing chamber transfer device) separate from the carburizing chamber transfer device 71 may be used to move the preceding work carrier row (preceding work row) in the transfer direction H2. The second carburizing chamber transfer device may be any device that can simultaneously move the entire preceding work carrier row (preceding work row) in the transfer direction H2, but it is envisioned that it may be configured, for example, by a device such as a roller conveyor (roller hearth type) that is driven by a drive source and transfers the work carrier Tc in the transfer direction H2. However, it is not limited to this and may be configured by other types of transfer devices.

[0046] <Carburizing chamber> The carburizing chamber 3 will be described with reference to FIG. 2. The carburizing chamber 3 is composed of an airtight, heat-resistant container or furnace. An opening, the carburizing chamber entrance 30A, is formed at the upstream end of the carburizing chamber 3 in the transport direction H2, i.e., at the boundary between the carburizing chamber 3 and the first connecting path 5A. A thermally insulated entrance door (carburizing chamber entrance door) 32A, which can be opened and closed by a reciprocating drive mechanism 33A, is located at the carburizing chamber entrance 30A. The thermally insulated entrance door 32A is made of a thermal insulating material and prevents heat from the carburizing chamber 3 from being transferred to the antechamber 2. The reciprocating drive mechanism 33A may be composed, for example, of a chain (not shown) connected to the thermally insulated entrance door 32A and a drive mechanism (not shown) that winds and unwinds the chain. The thermally insulated entrance door 32A may be moved up and down by an air cylinder.

[0047] An opening, carburizing chamber outlet 30B, is formed at the downstream end of the carburizing chamber 3 in the transport direction H2, i.e., at the boundary between the quenching chamber 4 and the second connecting path 5B. A heat-insulating exit door (carburizing chamber exit door) 32B that can be opened and closed by a reciprocating drive mechanism 33B is disposed at this carburizing chamber outlet 30B. The heat-insulating exit door 32B prevents heat from being transmitted from the carburizing chamber 3 to the quenching chamber 4. The reciprocating drive mechanism 33B is composed of, for example, a chain (not shown) connected to the heat-insulating exit door 32B and a drive mechanism (not shown: for example, a winch) that winds and unwinds the chain.

[0048] The carburizing chamber 3A is large enough to accommodate multiple workpiece carriers Tc lined up in a row along the transfer direction H2. A transfer path 27 for transferring the workpiece carriers Tc in the transfer direction H2 is provided in the carburizing chamber 3A. The multiple workpiece carriers Tc are lined up in a row on the transfer path 27 in the transfer direction H2. Rollers or the like may be arranged on the transfer path 27 to reduce transfer resistance.

[0049] If at least one preceding workpiece carrier Tc has already been carried into the carburizing chamber 3, when the subsequent workpiece carrier Tc is carried into the carburizing chamber 3 by the carburizing chamber transfer device 71, the preceding at least one workpiece carrier Tc is shifted downstream in the transfer direction H2 from its current position. Of the preceding at least one workpiece carrier Tc, the workpiece carrier Tc at the end (most upstream) of the line may be pushed and shifted in position by the subsequent workpiece carrier Tc being transferred from the anterior chamber 2 by the carburizing chamber transfer device (first carburizing chamber transfer device) 71, for example, or may be shifted in position by a second carburizing chamber transfer device separate from the carburizing chamber transfer device 71.

[0050] Next, the stopping positions of the multiple work carriers Tc lined up in a row inside the carburizing chamber 3A will be explained. The multiple work carriers Tc wait at preset stopping positions. Inside the carburizing chamber 3A, a first waiting position, a second waiting position, ..., an Nth waiting position are provided, in order from the upstream side of the transport direction H2, as waiting positions for N (16 in FIG. 1) work carriers Tc (group of workpieces W) to wait (temporarily stop). When a work carrier Tc temporarily stopped at the first waiting position is shifted downstream in the transport direction H2 from its current position by the first carburizing chamber transport device or the second carburizing chamber transport device, that work carrier Tc moves to the second waiting position and temporarily stops. In accordance with this, the other work carriers Tc also move to adjacent waiting areas downstream. This movement of the work carrier Tc is performed each time a subsequent work carrier Tc is carried in from the antechamber 2.

[0051] The carburizing chamber 3 also has a heating device 31 for heating the workpiece W in the carburizing chamber 3A, and a stirrer 34 provided in the carburizing chamber 3A.

[0052] The heating device 31 has multiple heaters 31A that heat the carburizing chamber 3A and a temperature sensor (not shown). The multiple heaters 31A are arranged at intervals in the transport direction H2. The multiple heaters 31A may be, for example, radiant tube heaters, but are not limited to these and may be other types of heaters.

[0053] It is preferable that a temperature sensor is provided in each of the sections (heating section S1, carburizing section S2, diffusion section S3, and cooling section S4) described later inside the carburizing chamber 3A.

[0054] Preferably, each of the plurality of heaters 31A is configured so that heating can be individually controlled by a control device 100, which will be described later, based on the measurement results of each temperature sensor.

[0055] The agitator 34 is provided on the ceiling surface of the carburizing chamber 3A and agitates the atmospheric gas inside the carburizing chamber 3A. It is preferable that an agitator 34 be provided in each of the sections (heating section S1, carburizing section S2, diffusion section S3, and temperature decreasing section S4) described below, but this is not limitative and an agitator 34 may be provided in only one specific section or multiple sections. The agitator 34 is, for example, formed from a centrifugal fan.

[0056] The carburizing chamber 3 is preferably provided with an exhaust path 36 and an on-off valve 36A for exhausting gas from the carburizing chamber 3A when purging the carburizing chamber 3A with a carrier gas. The exhaust path 36 and the on-off valve 36A are preferably provided at least in the temperature-rise section S1 (described later) of the carburizing chamber 3A, and in the diffusion section S3 and / or temperature-drop section S4 (described later). In particular, providing exhaust paths 36 in the temperature-rise section S1 and temperature-drop section S4 allows carrier gas supplied from the carburizing section S2 to flow into the most upstream temperature-rise section S1 and the most downstream temperature-drop section S4, thereby filling the entire carburizing chamber 3 with carrier gas. Furthermore, the first airflow formed by the flow of residual gas (carrier gas) from the carburizing section S2, via the temperature-rise section S1, into the exhaust path 36 in the temperature-rise section S1 suppresses the inflow of oxygen, water vapor, and the like from the carburizing chamber inlet 30A. Similarly, the second airflow formed by the flow of residual gas (carrier gas) flowing from the carburizing section S2 through the temperature-reducing section S4 and into the exhaust path 36 of the temperature-reducing section S4 suppresses the inflow of oxygen, water vapor, etc. from the carburizing chamber outlet 30B. This improves the carburizing characteristics of the workpiece W and suppresses carburizing variations and sooting. It is desirable that the carburizing chamber 3 be an airtight structure (pressure chamber) in order to maintain and control the internal pressure of the carburizing chamber 3A and reduce the amount of carrier gas used.

[0057] In addition, in this embodiment, an example has been given of purging the gas present in the carburizing chamber 3A with a carrier gas, but this is not limited to this, and the purge gas from the anterior chamber 2 may be introduced into the carburizing chamber 3A via the first connecting passage 5A to expel impurities from the carburizing chamber 3A.

[0058] Heat insulating material (not shown) is provided on the inner wall of the carburizing chamber 3A to maintain the temperature inside the carburizing chamber 3A. Furthermore, the carburizing chamber 3A is provided with an exhaust port (not shown) for discharging the atmospheric gas inside the carburizing chamber 3A to the outside of the furnace, and the carburizing chamber 3A is maintained at normal pressure (approximately atmospheric pressure: about 101 kPa) or a higher pressure than normal during carburizing.

[0059] In gas carburizing equipment, the carburizing process is carried out in the carburizing chamber 3A at normal pressure or a pressure higher than normal pressure. As a result, outside air (oxygen) is not drawn into the carburizing chamber 3A during the carburizing process, improving the carburizing quality. In this case, the carburizing process may be carried out at a pressure slightly higher than normal pressure (atmospheric pressure). A pressure slightly higher than normal pressure means, for example, a pressure in the range of above normal pressure and less than +10% of normal pressure. For example, a pressure of +5% or less of normal pressure is preferable, and a pressure of +1% or less of normal pressure is even more preferable.

[0060] <Multiple sections of the carburizing chamber> The carburizing chamber 3 is divided into multiple sections along the transport direction H2. The multiple sections include, for example, a temperature-raising section S1, a carburizing section S2, a diffusion section S3, and a temperature-reducing section S4. The temperature-raising section S1, the carburizing section S2, the diffusion section S3, and the temperature-reducing section S4 are arranged in this order from upstream to downstream in the transport direction H2.

[0061] The temperature-raising section S1 is the first section in the carburizing chamber 3A aligned in the transport direction H2, and is a section for performing a temperature-raising process to raise the temperature of the workpieces W accommodated in the workpiece carrier Tc to a predetermined carburizing temperature T1 (a temperature suitable for carburizing). For this reason, the temperature-raising section S1 is maintained at the carburizing temperature T1 by the heating device 31.

[0062] Then, the workpiece carrier Tc passes from the most upstream standby position in the temperature rise section S1 to the most downstream standby position over the temperature rise time t1, which includes the preset soaking time t5 of the workpiece W, and then moves to the next carburizing section S2. The temperature rise time t1 refers to the time during which the temperature rise process is performed on a specific workpiece W in the temperature rise section S1. In this embodiment, the workpiece carrier Tc moves intermittently in the transfer direction H2 due to the pressing force of the pressing device 71A, staying in the temperature rise section S1 for a total of the temperature rise time t1, and then moves to the next carburizing section S2. In FIG. 2, the temperature rise section S1 includes multiple standby positions (first standby position to fourth standby position), and the carburizing section S2 includes multiple standby positions (fifth standby position to eighth standby position). The workpiece carrier Tc passes through multiple standby positions (first standby position (most upstream standby position) to fourth standby position (most downstream standby position)) over the temperature rise time t1, and then reaches the most upstream standby position (fifth standby position) in the carburizing section S2.

[0063] As shown in the time chart of the workpiece W in FIG. 4, the workpiece W accommodated in the workpiece carrier Tc transported to the temperature rising section S1 remains in the temperature rising section S1 for a further soaking time t5 even after the temperature rises and reaches the carburizing temperature T1.

[0064] The carburizing section S2 is the next section following the temperature-raising section S1, and is a section in which a carburizing gas supply process is performed on the workpiece W whose temperature has been raised to the carburizing temperature T1 in the temperature-raising section S1. The carburizing gas supply process refers to the process of supplying a carrier gas and carburizing gas to the workpiece W. As shown in the time chart for the workpiece W in Figure 4, in the carburizing section S2, the workpiece W is maintained at the carburizing temperature T1 while a carrier gas and carburizing gas are supplied.

[0065] Then, the workpiece carrier Tc passes from the most upstream standby position to the most downstream standby position in the carburizing section S2 during a preset carburizing time t2 for the workpiece W, and then moves to the next diffusion section S3. The carburizing time t2 for the workpiece W refers to the time during which carrier gas and carburizing gas are supplied to a specific workpiece W in the carburizing section S2. In this embodiment, the workpiece carrier Tc moves intermittently in the transfer direction H2 due to the pressing force of the pressing device 71A, staying in the carburizing section S2 for a total of the carburizing time t2, and then moves to the next diffusion section S3. In FIG. 2, the carburizing section S2 includes the fifth standby position to the eighth standby position, and the diffusion section S3 includes the ninth standby position to the twelfth standby position, and it is sufficient for the workpiece carrier Tc to pass from the fifth standby position (the most upstream standby position) to the eighth standby position (the most downstream standby position) over the carburizing time t2, and then reach the ninth standby position in the diffusion section S3.

[0066] The carburizing gas supplied to the carburizing section S2 is preferably a gas containing acetylene (C2H2) (hereinafter referred to as acetylene-containing gas). When acetylene is adsorbed onto the workpiece W, it is decomposed into carbon and hydrogen according to the reaction (C2H2 → 2C + H2), and the carbon C is absorbed into the workpiece W. Furthermore, acetylene has a fast decomposition (carburization) rate. Therefore, by adjusting the acetylene concentration in the atmosphere during the carburizing process in the carburizing section S2, almost all of the acetylene supplied to the carburizing section S2 is adsorbed and decomposed by the workpiece W placed in the carburizing section S2, and it is possible to prevent excess acetylene from the carburizing section S2 from flowing into the adjacent heating section S1 and diffusion section S3. As a result, the gases supplied to the temperature rise section S1 and the diffusion section S3 are almost exclusively carrier gas and hydrogen (H2), which means that there is almost no possibility of unexpected carburization, decarburization, sooting, oxidation, etc. occurring in the temperature rise section S1 and the diffusion section S3.

[0067] To achieve the above control, in this embodiment, an acetylene concentration measuring sensor 1000 that measures the acetylene concentration is installed in the carburizing section S2 to monitor the acetylene concentration in the atmosphere of the carburizing section S2. An example of the acetylene concentration measuring sensor 1000 is an infrared absorption type. The measurement results from the acetylene concentration measuring sensor 1000 are fed back to a control device 100 (described later). Based on the measurement results, the control device 100 controls the opening and closing of an on-off valve 90B (see FIG. 2) of a carburizing gas system 90 (described later) to control the amount of acetylene supplied per unit time. As a result, the acetylene concentration in the atmosphere of the carburizing section S2 is adjusted. Note that if the acetylene concentration in the atmosphere of the carburizing section S2 measured by the acetylene concentration measuring sensor 1000 is outside a predetermined range, a warning means (not shown) may be configured to warn an external party of the abnormality.

[0068] Acetylene concentration measuring sensors (not shown) may also be provided in other sections such as the temperature rising section S1, the diffusion section S3, etc. If an acetylene concentration equal to or higher than a preset threshold is detected in another section, the control device 100 may control the opening and closing of an on-off valve 90B (see FIG. 2) of the carburizing gas system 90 (described later) based on the measurement result, thereby controlling the amount of acetylene supplied per unit time and thereby controlling the acetylene concentration, or may be configured to notify the outside of an abnormality using an alarm means (not shown).

[0069] The diffusion section S3 is the next section following the carburizing section S2, in which the carbon that has penetrated into the workpiece W is appropriately diffused to form a hardened layer with the desired carbon concentration and thickness (carburization depth) on the workpiece W. As shown in the time chart for the workpiece W in Figure 4, the diffusion section S3 is maintained at the carburizing temperature T1 by the heating device 31 with only carrier gas and hydrogen (H2) (hereinafter referred to as carrier gas, etc.) being supplied.

[0070] Then, the workpiece carrier Tc passes from the most upstream standby position in the diffusion section S3 to the most downstream standby position within the predetermined diffusion time t3 for the workpiece W, and moves to the next temperature-reducing section S4. This allows a hardened layer to be formed on the surface of the workpiece W. The diffusion time t3 refers to the time required to perform the diffusion process on a specific workpiece W within the diffusion section S3. In this embodiment, the workpiece carrier Tc moves intermittently in the transfer direction H2 due to the pressing force of the pressing device 71A, staying in the diffusion section S3 for a total of the diffusion time t3 before moving to the next temperature-reducing section S4. As described above, if the amount of carburizing gas supplied per unit time is controlled to adjust the acetylene concentration in the mixed gas supplied to the carburizing section S2, the gas supplied to the diffusion section S3 will not contain acetylene and can be mainly composed of the carrier gas (nitrogen) and hydrogen (H2), so no problems will arise.

[0071] 2, the diffusion section S3 includes a plurality of standby positions (ninth standby position to twelfth standby position), and the temperature decreasing section S4 includes a plurality of standby positions (thirteenth standby position to sixteenth standby position). The work carrier Tc passes through the plurality of standby positions (ninth standby position (most upstream standby position) to twelfth standby position (most downstream standby position)) over the diffusion time t3, and then reaches the most upstream standby position (thirteenth standby position) of the temperature decreasing section S4.

[0072] The temperature-reducing section S4 is the next section following the diffusion section S3, and is a section for controlling the heating device 12 to reduce the temperature of the workpiece W to a preset quenching holding temperature T2. In the temperature-reducing section S4, the heating device 31 maintains the quenching holding temperature T2 while a carrier gas or the like is supplied. The quenching holding temperature T2 is preferably in the range of 800°C to 880°C, and more preferably in the range of 830°C to 850°C.

[0073] Then, the workpiece carrier Tc passes from the most upstream standby position to the most downstream standby position in the temperature reduction section S4 in a preset temperature reduction time t4 for the workpiece W, and moves to the next quenching chamber 4 in a state where its temperature has been reduced to the quenching holding temperature T2. Note that the temperature reduction time t4 refers to the time during which the temperature of a specific workpiece W is reduced to the quenching holding temperature T2 in the temperature reduction section S4 and maintained at that temperature. In this embodiment, the workpiece carrier Tc only needs to stay in the temperature reduction section S4 for a total of the temperature reduction time t4 while moving intermittently in the conveying direction H2 due to the pressing force of the pressing device 71A, and then move to the next quenching chamber 4.

[0074] 2, the temperature decreasing section S4 includes a plurality of standby positions (a thirteenth standby position to a sixteenth standby position). The workpiece carrier Tc passes through the plurality of standby positions (the thirteenth standby position (the most upstream standby position) to the sixteenth standby position (the most downstream standby position)) over the temperature decreasing time t4 before reaching the next quenching chamber 4.

[0075] As shown in the time chart of the workpiece W in FIG. 4, the workpiece W accommodated in the workpiece carrier Tc transported to the temperature-reducing section S4 remains in the temperature-reducing section S4 for a further quenching retention time t6 even after the temperature is reduced to the quenching retention temperature T2.

[0076] As described above, by dividing a single transport path into multiple sections, the carburizing process can be carried out efficiently and in a short time. In this embodiment, the carburizing process refers to a process that includes at least a temperature increase process, a carburizing gas supply process, and a diffusion process. The carburizing process may also include a temperature decrease process. The carburizing chamber 3 functions as a continuous furnace, since it performs different processes on the moving workpiece in each section while controlling the heating.

[0077] Partition walls 37 may be provided at the boundaries of each section (heating section S1, carburizing section S2, diffusion section S3, and cooling section S4). The partition walls 37 extend downward from the upper wall of the carburizing chamber 3A at the boundaries of each section to a position where they do not interfere with the work carrier Tc (workpiece W). The position where the partition wall 37 does not interfere with the work carrier Tc (workpiece W) refers to a position before the passing area through which the work carrier Tc (workpiece W) passes during transportation.

[0078] The partition wall 37 forms an area surrounded by the partition wall 37 and the wall that forms the carburizing chamber 3. Therefore, for example, in the carburizing section S2, a mixed gas of acetylene and a carrier gas can be retained in that area, and acetylene is actively consumed in the carburizing section S2. As a result, the amount of residual acetylene in the carburizing section S2 is reduced, and the amount of acetylene flowing into the temperature-rise section S1 and the diffusion section S3 can be suppressed. In other words, the temperature-rise section S1, the diffusion section S3, and the temperature-fall section S4 are mainly filled with the carrier gas for the carburizing section S2 and hydrogen gas, which is a product of the carburizing reaction. This suppresses the carburizing reaction in these sections (S1, S3, S4). Furthermore, because the diffusion section S3 and the temperature-fall section S4 are set to different temperatures, the presence of the partition wall 37 reduces the mutual influence of the temperatures in the diffusion section S3 and the temperature-fall section S4.

[0079] Each workpiece carrier Tc lined up in a row in the carburizing chamber 3A moves to an adjacent downstream standby position in the transfer direction H2 at the same time each time a workpiece carrier Tc is carried in from the antechamber 2. Therefore, as shown in Figure 2, if the temperature rise section S1, carburizing section S2, diffusion section S3, and temperature fall section S4 each have four standby positions, the temperature rise time t1, carburizing time t2, diffusion time t3, and temperature fall time t4 will be the same. By changing the number of standby positions in each of the temperature rise section S1, carburizing section S2, diffusion section S3, and temperature fall section S4, the temperature rise time t1, carburizing time t2, diffusion time t3, and temperature fall time t4 can each be freely set. If the time from when the previous workpiece is transferred from the antechamber 2 to the carburizing chamber 3 by the carburizing chamber transfer device 71 until the next workpiece is transferred from the antechamber 2 to the carburizing chamber 3 is defined as reference time S, the number of standby positions within the temperature rise section S1 is defined as a first number N1, the number of standby positions within the carburizing section S2 is defined as a second number N2, the number of standby positions within the diffusion section S3 is defined as a third number N3, and the number of standby positions within the temperature drop section S4 is defined as a fourth number N4, then the first number N1 is expressed as the ratio of the temperature rise time t1 to the reference time S (N1 = t1 / S). The second number N2 is expressed as the ratio of the carburizing time t2 to the reference time S (N2 = t2 / S). The third number N3 is expressed as the ratio of the diffusion time t3 to the reference time S (N3 = t3 / S). The fourth number N4 is expressed as the ratio of the temperature drop time t4 to the reference time S (N4 = t4 / S). For example, if the time (reference time) from transporting the workpiece carrier Tc to the anterior chamber 2, through the negative pressure generation process in the anterior chamber 2, to completing the anterior chamber purging process is set to 15 minutes, the temperature rise time t1 is set to 30 minutes, the carburization time t2 is set to 90 minutes, the diffusion time t3 is set to 120 minutes, and the temperature drop time t4 is set to 30 minutes, then there will be two standby positions in the temperature rise section S1, six standby positions in the carburization section S2, eight standby positions in the diffusion section S3, and two standby positions in the temperature drop section S4. In this embodiment, it is preferable to satisfy N1≦N2. It is also preferable to satisfy N2≦N3+N4.

[0080] <Source gas supply device> A raw material gas supply device 9 is connected to the carburizing chamber 3, which supplies various gases to the carburizing chamber 3A. The raw material gas supply device 9 has a carburizing gas system 90 through which carburizing gas flows, a carrier gas system 92 through which carrier gas flows, and a carburizing section supply system 94 that supplies the gases flowing through the carburizing gas system 90 and the carrier gas system 92 to the carburizing section S2 inside the carburizing chamber 3A. The raw material gas supply device 9 also has a hydrocarbon supply source 96 connected to the carburizing gas system 90 and a nitrogen supply source 98 connected to the carrier gas system 92. In this embodiment, direct carburizing, in which the carbon contained in the carburizing gas directly penetrates the workpiece W, is performed under normal pressure, so the term "carburizing gas" is used instead of "enriched gas."

[0081] <Hydrocarbon Source> The hydrocarbon supply source 96 generates a hydrocarbon-containing gas containing a chain unsaturated hydrocarbon as the carburizing gas. In this embodiment, acetylene (C2H2) is preferred as the chain unsaturated hydrocarbon in the hydrocarbon-containing gas, considering the aforementioned fast decomposition (carburization) rate, high adsorption to steel, the fact that the triple bond makes it more reactive, and ease of availability. It is preferable to use acetylene with a purity of, for example, 95% by volume or higher, and more preferably, 98% by volume or higher. The hydrocarbon-containing gas may contain impurities other than the chain unsaturated hydrocarbon, but the amount of these impurities is preferably kept low. Therefore, for example, when the chain unsaturated hydrocarbon is acetylene, it is preferable that the hydrocarbon-containing gas is not generated using a solvent such as acetone or dimethylformamide (DMF) in the hydrocarbon supply source 96.

[0082] However, as the chain unsaturated hydrocarbon in the hydrocarbon-containing gas, other than acetylene, other chain unsaturated hydrocarbons having a triple bond such as propyne (CH3C≡CH) or 1-butyne (CH3CH2C≡CH) may be used, or other chain unsaturated hydrocarbons having a double bond such as ethylene (HC=CH2) or butadiene (CH2=CH-CH=CH2) may be used. Multiple types of chain unsaturated hydrocarbons may be mixed.

[0083] <Carburizing gas system> As shown in FIG. 2, the carburizing gas system 90 includes a supply pipe 90A connected to a hydrocarbon supply source 96, an on-off valve 90B attached to the supply pipe 90A, and a flow meter 90C. The supply pipe 90A is connected to the hydrocarbon supply source 96, through which carburizing gas flows. The on-off valve 90B is a solenoid valve attached to the supply pipe 90A. The on-off valve 90B opens and closes the flow path and adjusts the flow rate of the carburizing gas. The flow meter 90C is attached to the supply pipe 90A downstream of the on-off valve 90B and measures the flow rate of the carburizing gas flowing through the supply pipe 90A. The on-off valve 90B only opens and closes the flow path. Alternatively, a separate flow control valve (not shown) may be provided to adjust the flow rate of the carburizing gas, allowing manual adjustment of the carburizing gas flow rate while checking the readings on the flow meter 90C. The end of the supply pipe 90A is connected to a mixer 93 in the carburizing section supply system 94.

[0084] <Nitrogen source> The nitrogen supply source 98 generates a nitrogen-containing gas containing nitrogen (neutral gas or inert gas). This nitrogen-containing gas serves as a carrier gas. In this embodiment, the nitrogen supply source 98 includes a gas separation device 98A, which is a PSA-type nitrogen gas generator. The gas separation device 98A separates nitrogen from air using pressure swing adsorption (PSA) to generate the nitrogen-containing gas. Therefore, the nitrogen-containing gas contains oxygen as an impurity in addition to nitrogen. Note that the nitrogen-containing gas that serves as the carrier gas preferably has a nitrogen volume percentage of 99.00% or more. Furthermore, it is preferable that the oxygen volume percentage in the nitrogen-containing gas be 0.001% or more and 1.00% or less.

[0085] The nitrogen supply source 98 may supply the nitrogen-containing gas using a method other than the pressure swing adsorption method. For example, the nitrogen-containing gas may be generated and supplied using a nitrogen gas cylinder.

[0086] <Carrier gas system> The carrier gas system 92 includes a supply pipe 92A, an on-off valve 92B, and a flow meter 92C. A first end of the supply pipe 92A is connected to a nitrogen supply source 98, and a second end of the supply pipe 92A is connected to a mixer 93 of a carburizing section supply system 94.

[0087] Carrier gas or carrier gas to which a small amount of carburizing gas has been added in a gas mixer 91 flows through the supply pipe 92A. This carrier gas is guided to a mixer 93 in a carburizing section supply system 94. An on-off valve 92B is a solenoid valve that is provided midway through the supply pipe 92A. The on-off valve 92B opens and closes the flow path and adjusts the flow rate of the carrier gas. A flow meter 92C is provided on the supply pipe 92A downstream of the on-off valve 92B and measures the flow rate of the carrier gas flowing through the supply pipe 92A. Note that the on-off valve 92B only opens and closes the flow path, and a flow rate adjustment valve (not shown) that adjusts the flow rate of the carrier gas may be provided separately from the on-off valve 92B, and the flow rate of the carrier gas may be adjusted manually while checking the readings on the flow meter 92C.

[0088] When only carrier gas is supplied to the carburizing section S2, as in the carburizing chamber preparation process described below, the gas mixer 91 is stopped, the on-off valve 92B of the carrier gas line 92 is opened, and the on-off valve 90B of the carburizing gas line 90 is closed. The supply flow rate of the carrier gas is not particularly limited and may be set appropriately depending on the airtightness of the carburizing chamber, the volume of the carburizing chamber 3A, the surface area of ​​the workpiece W, the hardening depth required for the workpiece W, etc.

[0089] <Carburizing section supply system> The carburizing section supply system 94 has a mixer 93, and a first branch portion 941 and a second branch portion 942 that branch into two from the output side of the mixer 93. The input side of the mixer 93 is connected to a supply pipe 90A of the carburizing gas system 90 and a supply pipe 92A of the carrier gas system 92. The mixer 93 has the function of mixing the carburizing gas supplied from the upstream carburizing gas system 90 and the carrier gas supplied from the carrier gas system 92.

[0090] A first gas supply nozzle 941D is provided at the tip of the first branch portion 941, and a second gas supply nozzle 942D is provided at the tip of the second branch portion 942. The first gas supply nozzle 941D and the second gas supply nozzle 942D are provided above the carburizing chamber 3 in the carburizing section S2. The first gas supply nozzle 941D and the second gas supply nozzle 942D are provided with an interval in the transfer direction H2. The first gas supply nozzle 941D has a first supply port 941E that opens into the carburizing chamber 3A in the carburizing section S2. The second gas supply nozzle 942D has a second supply port 942E that opens into the carburizing chamber 3A in the carburizing section S2. From the first supply port 941E and the second supply port 942E, carburizing gas from the carburizing gas system 90 and carrier gas from the carrier gas system 92 are sprayed (or flowed) downward in the carburizing section S2.

[0091] Alternatively, the first gas supply nozzle 941D may be provided in the upper part of the carburizing chamber 3 in the carburizing section S2, and the second gas supply nozzle 942D may be provided in the lower part of the carburizing chamber 3. In this case, the carburizing gas from the carburizing gas system 90 and the carrier gas from the carrier gas system 92 are ejected (or flowed out) downward in the vertical direction from the first supply port 43a, and the carburizing gas from the carburizing gas system 90 and the carrier gas from the carrier gas system 92 are ejected upward in the vertical direction from the second supply port 44a.

[0092] Regardless of the arrangement pattern of the first gas supply nozzle 941D and the second gas supply nozzle 942D, it is preferable that the first gas supply nozzle 941D and the second gas supply nozzle 942D are arranged so that the carburizing gas is sprayed (or flowed out) evenly onto the workpiece W placed in the carburizing section S2 of the carburizing chamber 3.

[0093] The first branch section 941 and the second branch section 942 each include branch pipes 941A and 942A, on-off valves 941B and 942B, and flow meters 941C and 942C. These on-off valves 941B and 942B are solenoid valves that adjust the flow rates of gas flowing through the branch pipes 941A and 942A, thereby enabling adjustment of the ratio of the flow rates of gas flowing through the branch pipes 941A and 942A. The on-off valves 941B and 942B may be provided on only one of the branch pipes 941A and 942A. Alternatively, the on-off valves 941B and 942B may only open and close the flow path, and a flow rate adjustment valve (not shown) may be provided separately from the on-off valves 941B and 942B to adjust the flow rate of gas flowing through the branch pipes 941A and 942A, and the flow rate of gas flowing through the branch pipes 941A and 942A may be manually adjusted while checking the readings of the flow meters 941C and 942C.

[0094] In the above, the carburizing section supply system 94 has been exemplified as having a first branch portion 941 and a second branch portion 942 that branch into two from the output side of the mixer 93, but it is not limited to this, and a single flow path type that does not branch, or a type that branches into three or more paths, are also within the scope of the present invention. However, in any case, it is preferable that the gas supply nozzles in the carburizing section supply system 94 are provided above and / or below the carburizing section S2, and configured so that the carburizing gas and carrier gas are sprayed (or flowed out) downward and / or upward.

[0095] Although not shown here, in order to perform sulfurizing-carburizing and sulfuric-carbonitriding, the raw material gas supply device 9 may further include a hydrogen sulfide supply source and a hydrogen sulfide gas supply system for supplying hydrogen sulfide gas to the carburizing chamber 3A. The raw material gas supply device 9 may also additionally supply ammonia as a raw material gas.

[0096] <Application example of carrier gas supply system> 2, a gas mixer 91 may be provided upstream of an on-off valve 92B in a carrier gas system 92. This gas mixer 91 is provided upstream of the on-off valve 92B and a flow meter 92C, and serves to add a small amount of carburizing gas from a carburizing gas system 90 to the carrier gas (nitrogen gas) of a nitrogen supply source 98 as needed. For this reason, the carburizing gas system 90 is provided with a supply pipe 91A that branches off from a supply pipe 90A and is connected to the gas mixer 91. The flow rate (amount added) of the carburizing gas flowing through the supply pipe 91A is measured by a flow meter 91B, and the flow rate is adjusted by an on-off valve 91C.

[0097] A portion of the carrier gas to which a trace amount of carburizing gas has been added via gas mixer 91 flows through supply pipe 92A and into mixer 93, while the remainder flows through dedicated carrier gas pipe 91D, which branches off from supply pipe 92A. The downstream end of dedicated carrier gas pipe 91D is connected to temperature rise section S1. A flow meter 91E and an on-off valve 91F are provided in the dedicated carrier gas pipe 91D, and the amount of carrier gas to which a trace amount of carburizing gas has been added that is supplied to temperature rise section S1 is adjusted.

[0098] In this embodiment, oxygen is prevented from entering the temperature rise section S1, so in normal operation, oxygen does not have any adverse effects in the temperature rise section S1. However, if oxygen or water (steam) enters the temperature rise section S1 due to some event, it will preferentially adsorb to the surface of the workpiece W during temperature rise, hindering carburization.

[0099] Therefore, by opening the on-off valve 91F, carrier gas with a trace amount of carburizing gas added is supplied directly to the temperature-rising section S1. Specifically, water (water vapor) that enters the temperature-rising section S1 can be decomposed in the temperature-rising section S1 to generate hydrogen and oxygen, but the carrier gas with a trace amount of carburizing gas added is used to react acetylene with water to generate carbon monoxide and hydrogen, as shown in the following formula (1). This reduces the moisture concentration in the temperature-rising section S1. C2H2+2H2O→2CO+3H2 (1)

[0100] Furthermore, oxygen that enters the temperature rise section S1 is preferentially adsorbed onto the surface of the workpiece W, hindering carburization. However, as shown in the following equation (2), a small amount of acetylene added to the carrier gas reacts with oxygen to produce carbon monoxide and hydrogen. This reduces the oxygen concentration in the temperature rise section S1. C2H2+O2→2CO+H2 (2)

[0101] The amount of carburizing gas added directly to the temperature increasing section S1 is preferably sufficiently smaller than the volume of the carrier gas (nitrogen-containing gas), for example, 0.01% by volume or more and 3.0% by volume or less relative to the carrier gas.

[0102] It is also possible to increase the concentration of the carburizing gas supplied from the carburizing gas system 90 to the carburizing section S2 via the carburizing section supply system 94, thereby supplying excess acetylene to the carburizing section S2, causing a small amount of acetylene to leak into the temperature-raising section S1 via the carburizing section S2. This acetylene may be used to reduce the water and oxygen in the temperature-raising section S1.

[0103] <Second Connection> A tunnel-shaped second connecting passage 5B is arranged between the carburizing chamber 3 and the quenching chamber 4, connecting them. A carburizing chamber outlet 30B is formed as an opening on the carburizing chamber 3 side of the second connecting passage 5B (upstream side in the transport direction H2). The second connecting passage 5B connects the carburizing chamber 3 and the quenching chamber 4 in an airtight manner that prevents gas from entering from the outside space. A transport passage 27 is provided within the second connecting passage 5B for transporting the workpiece carrier Tc in the transport direction H2. The guide rails of the transport passage 27 guide the workpiece carrier Tc transported via the second connecting passage 5B to the quenching chamber 4.

[0104] <Quenching chamber transport device> The quenching chamber transfer device 73 transfers workpiece carriers Tc (hereinafter referred to as carburized workpiece carriers) that contain workpieces W that have been carburized and whose temperature has been lowered to the quenching holding temperature T2 in the temperature lowering section S4 to the quenching chamber 4. In this embodiment, the quenching chamber transfer device 73 transfers the carburized workpiece carriers Tc one by one to the quenching chamber 4. In this case, the quenching chamber transfer device 73 is configured to transfer the carburized workpiece carrier Tc that is located at the front (most upstream) of the line within the carburizing chamber 3A to the quenching chamber 4.

[0105] The quenching chamber transport device 73 may be any device that can transport the workpiece carrier Tc in the transport direction H2. For example, similar to the anterior chamber transport device 70 in Fig. 1, the quenching chamber transport device 73 may include a hook that grips the workpiece carrier Tc, a snake chain that is disposed in the oil tank 4B of the quenching chamber 4 and moves the hook back and forth between the temperature lowering section S4 and the quenching chamber 4, and a drive source that drives the snake chain via a sprocket.

[0106] Furthermore, when the quenching chamber 4 is configured to be able to receive a plurality of carburized work carriers Tc, the quenching chamber transport device 73 may transport a plurality of carburized work carriers Tc simultaneously within the carburizing chamber 3A or transport them one by one to the quenching chamber 4.

[0107] <Quenching chamber and oil tank> The quenching chamber 4 is formed of a pressure-resistant metal container. The quenching chamber 4 has an oil-throwing area 4A and an oil tank 4B. The oil-throwing area 4A and the oil tank 4B are aligned vertically, and the oil tank 4B is located below the oil-throwing area 4A. The workpiece carrier Tc transported via the second connecting path 5B is temporarily placed in the oil-throwing area 4A.

[0108] The quenching chamber 4 may be configured to include a heating device (not shown) and a temperature sensor (not shown) so that at least the oil-slinging region 4A is maintained at the quenching holding temperature T2.

[0109] Furthermore, an opening, a quenching chamber entrance 40A, is formed at the upstream end of the quenching chamber 4 in the transport direction H2, i.e., at the boundary between the quenching chamber 4 and the second connecting path 5B. A quenching chamber entrance door 42A that can be opened and closed by a reciprocating drive mechanism 49A is disposed at this quenching chamber entrance 40A. By closing the quenching chamber entrance 40A, the quenching chamber entrance door 42A makes the quenching chamber entrance 40A airtight (a state in which gas does not flow).

[0110] An opening, a quenching chamber outlet 40B, is formed at the downstream end of the quenching chamber 4 in the transfer direction H2. A quenching chamber outlet door 42B that can be opened and closed by a reciprocating drive mechanism 49B is disposed at this quenching chamber outlet 40B. The quenching chamber outlet door 42B closes the quenching chamber outlet 40B, thereby making the quenching chamber outlet 40B airtight (a state in which gas does not flow).

[0111] When the quenching chamber entrance door 42A and the quenching chamber exit door 42B are closed, the entire quenching chamber 4 becomes an airtight space.

[0112] The oil-slinging area 4A is provided with a transport path 27 for transporting the workpiece carrier Tc in the transport direction H2. Guide rails of the transport path 27 guide the workpiece carrier Tc to the workpiece unloading area 6 along the transport direction H2.

[0113] The oil tank 4B stores oil for quenching when hardening the workpiece W. As shown in Fig. 2, the oil tank 4B is equipped with a heater 46 for heating the oil, an agitator 47 for agitating the oil, and a heat exchanger 48 for cooling the oil. These devices allow the oil to be adjusted to a predetermined temperature.

[0114] An elevator device 40, which corresponds to a quenching moving device, is arranged in the quenching chamber 4. The elevator device 40 is installed between the oil-slinging area 4A and the oil tank 4B. The elevator device 40 raises and lowers the workpiece carrier Tc between the oil-slinging area 4A and the oil tank 4B.

[0115] As shown in FIG. 2, the lifting device 40 includes rails 43 extending in the arrangement direction (vertical direction) of the oil-slinging area 4A and the oil tank 4B, an elevator body 44 guided by the rails 43 in the arrangement direction, and a drive mechanism 45 that moves the elevator body 44 up and down. The drive mechanism 45 includes a lifting wire connected to the elevator body 44 and an electric drive mechanism that winds up the lifting wire. A conveying path 27 for conveying the work carrier Tc is provided within the elevator body 44. The lifting device 40 allows the elevator body 44 to move up and down (reciprocating) between the oil-slinging area 4A and the oil tank 4B. As the elevator body 44 moves up and down (reciprocating), a portion of the conveying path 27 within the elevator body 44 can also move up and down (reciprocating) between the oil-slinging area 4A and the oil tank 4B by the lifting device 40.

[0116] When the oil-slinging area 4A and the oil tank 4B are configured to be able to accommodate a plurality of work carriers Tc, the lifting device 40 can simultaneously lift and lower the plurality of work carriers Tc between the oil-slinging area 4A and the oil tank 4B.

[0117] <Quenching chamber negative pressure generating device> The quenching chamber negative pressure generating device 87 creates a negative pressure in the quenching chamber 4. Specifically, the quenching chamber negative pressure generating device 87 has a vacuum pump (negative pressure generating source) 87A, a degassing flow path 87B, and an on-off valve 87C. The degassing flow path 87B connects the quenching chamber 4 to the vacuum pump 87A. The vacuum pump 87A sucks (degasses) the gas inside the quenching chamber 4, thereby creating a negative pressure in the quenching chamber 4. Although not specifically shown, a filter or the like that adsorbs oil contained in the exhaust gas may be provided in the exhaust path beyond the vacuum pump 87A. An on-off valve 87C, which serves as an electromagnetic valve, is provided in the degassing flow path 87B and is opened during degassing.

[0118] The vacuum pump 87A may be omitted and the degassing passage 87B may be connected to the vacuum pump 81.

[0119] <Quenching chamber purge gas supply device> A quenching chamber purge gas supply device 89 is connected to the quenching chamber 4. The quenching chamber purge gas supply device 89 has a carrier gas system 89C through which carrier gas flows. The carrier gas system 89C has one end connected to a purge gas source (here, the same nitrogen supply source 98 as the carrier gas is also used) and the other end connected to the quenching chamber 4, a purge flow path 89A. An on-off valve 89B is arranged midway along the purge flow path 89A. The on-off valve 89B is configured as an electromagnetic valve. The quenching chamber purge gas supply device 89 supplies purge gas (here, nitrogen gas) to the quenching chamber 4, which has been degassed and placed in a negative pressure state by the quenching chamber negative pressure generating device 87, and this purge gas restores the quenching chamber 4 to normal pressure or a state higher than normal pressure (a restored pressure state).

[0120] <Work removal area> The workpiece unloading area 6 is an external area where the workpiece W that has been hardened in the quenching chamber 4 is unloaded. In the workpiece unloading area 6, for example, work is performed to ship the workpiece W that has been carburized and hardened.

[0121] <Export device> The carry-out device 74 carries out the work carriers Tc (hereinafter referred to as "hardened work carriers") that accommodate the workpieces W (hardened workpieces) that have been hardened in the quenching chamber 4, to the workpiece carry-out area 6. In this embodiment, the carry-out device 74 carries out the hardened workpiece carriers Tc to the workpiece carry-out area 6 one by one or multiple at the same time.

[0122] The carrying-out device 74 may be any device that can transport the workpiece carrier Tc in the transport direction H2. For example, similar to the anterior chamber transport device 70 in Fig. 1, the carrying-out device 74 may include a hook that grips the workpiece carrier Tc, a snake chain that is disposed in the workpiece carrying-out area 6 and moves the hook back and forth between the quenching chamber 4 and the workpiece carrying-out area 6, and a drive source that drives the snake chain via a sprocket.

[0123] <Control device> The control device 100 is a computer having a processor etc., and controls the entire gas carburizing device. As shown in Fig. 4(A), the control device 100 includes a CPU (Central Processing Unit) 101 that executes various programs, a memory 102 that temporarily stores information required by the CPU 101, an information storage medium 103 that stores programs and various data, and a communication interface 104 that communicates with various devices to be controlled.

[0124] <Individual functions of the control device> 4(B) shows the individual control functions of the controlled devices realized by the control program of the control device 10. The control device 10 includes a front chamber transport processing unit 110 that controls the transport of the work carrier Tc (work W) by the front chamber transport device 70, a front chamber entrance door opening / closing processing unit 111 that controls the reciprocating drive mechanism 23 to open and close the front chamber entrance door 22, a front chamber exit door opening / closing processing unit 112 that controls the reciprocating drive mechanism 25 to open and close the front chamber exit door 24, a front chamber degassing processing unit 113 that controls the vacuum pump 81 of the front chamber negative pressure generating device 80 to control the negative pressure state of the front chamber 2, a front chamber purge processing unit 114 that controls the front chamber purge gas supply device 84 to supply purge gas (here, nitrogen gas) to the front chamber 2, and a reciprocating drive mechanism 115 that controls the vacuum pump 81 of the front chamber negative pressure generating device 80 to control the negative pressure state of the front chamber 2. a heat insulating entrance door opening / closing unit 115 that controls the reciprocating drive mechanism 33A to open and close the heat insulating entrance door 32A; a heat insulating exit door opening / closing unit 116 that controls the reciprocating drive mechanism 33B to open and close the heat insulating exit door 32B; a carrier gas control unit 117 that controls the on-off valve 92B of the raw material gas supply device 9 to control the supply amount of carrier gas; a carburizing gas control unit 118 that controls the on-off valve 90B of the raw material gas supply device 9 to control the supply amount of carburizing gas; a carburizing chamber transport unit 71 that controls the movement of the work carrier Tc (work W) from the front chamber 2 to the carburizing chamber 3, or the movement of the work arranged in the carburizing chamber 3A; a carburizing chamber agitation processing unit 120 that controls the agitator 16 in the carburizing chamber 3; a carburizing chamber heating processing unit 121 that controls the heating device 31 in each section of the carburizing chamber 3A (heating section S1, carburizing section S2, diffusion section S3, and temperature decreasing section S4); a quenching chamber entrance door opening / closing processing unit 122 that controls the reciprocating drive mechanism 49A to open and close the quenching chamber entrance door 42A; a quenching chamber exit door opening / closing processing unit 123 that controls the reciprocating drive mechanism 49B to open and close the quenching chamber exit door 42B; and a quenching chamber transport device 73. a quenching chamber transport control unit 124 that controls the movement of the work carrier Tc (work W) to the quenching chamber 4 by controlling the above; a lifting processing unit 125 that controls the lifting device 40 that lifts and lowers the work carrier Tc (work W) between the oil throwing area 4A and the oil tank 4B; an oil tank heater processing unit 126 that controls the heater 46 of the oil tank 4B; an oil tank cooling processing unit 127 that controls the heat exchanger 48 of the oil tank 4B; an oil tank stirring processing unit 128 that controls the agitator 47 of the oil tank 4B; a quenching chamber degassing processing unit 129 that controls the vacuum pump 87A of the quenching chamber negative pressure generating device 87 to control the negative pressure state of the quenching chamber 4;It has a quenching chamber purge processing unit 130 that controls the quenching chamber purge gas supply device 89 to supply purge gas (here, nitrogen gas) to the quenching chamber 4, and a workpiece carry-out control unit 131 that controls the carry-out device 74 to control the movement of the workpiece carrier Tc (workpiece W) to the workpiece carry-out area 6.

[0125] In addition, when the work carrier Tc (work W) lined up in the carburizing chamber 3A is moved within the carburizing chamber 3A by the second carburizing chamber transport device (work moving mechanism 72), a second carburizing chamber transport control unit is separately provided which controls the second carburizing chamber transport device to control the movement within the carburizing chamber 3A of the work carrier Tc (work W) lined up in the carburizing chamber 3A.

[0126] <Controller integration functions> 4(C) shows the integrated control functions of the controlled devices implemented by the control program of the control device 10. The control device 10 has, as integrated control functions, an anterior chamber loading processing unit 150, an anteroom purge management unit 152, a carburizing chamber preparation processing unit 154, a carburizing chamber loading processing unit 156, a carburizing processing unit 158, a quenching chamber main purge management unit 160, a quenching chamber loading processing unit 162, a quenching processing unit 164, an oil draining processing unit 166, a quenching chamber pre-purge management unit 168, a workpiece unloading processing unit 170, an overall temperature management unit 171, and a fully automatic processing unit 172. These integrated control functions are linked with the individual control functions described above to achieve integrated control. Each integrated control function will be described below with reference to operational diagrams.

[0127] <Overall temperature control section> The overall temperature management unit 171 simultaneously operates the carburizing chamber agitation unit 120, the carburizing chamber heating unit 121, the oil bath heater unit 126, the oil bath cooling unit 127, and the oil bath agitation unit 128 to constantly maintain the target temperatures of the components, spaces, liquids, etc. in the gas carburizing apparatus. The overall temperature management unit 171 controls, for example, the heating device 31 to adjust the carburizing temperature T1 of the temperature increase section S1, the carburizing section S2, and the diffusion section S3 of the carburizing chamber 3 to 800°C or higher. For example, the carburizing temperature T1 is preferably controlled within a range of 880°C to 950°C, and more preferably 900°C to 930°C. The overall temperature management unit 171 is constantly running while the gas carburizing apparatus is in operation. The overall temperature management unit 171 controls, for example, the heating device 31 to adjust the temperature decrease section S4 to a preset quenching hold temperature T2. This quenching temperature T2 is preferably in the range of 800°C to 880°C, and more preferably in the range of 830°C to 850°C. The overall temperature control unit 171 may, for example, control a heating device (not shown) provided in the quenching chamber 4 to adjust the temperature inside the quenching chamber 4 to the same temperature as or close to the quenching temperature T2. The overall temperature control unit 171 may, for example, control a heating device (not shown) that heats the oil in the oil vat 4B to maintain the oil in the oil vat 4B at a predetermined quenching temperature T3. This quenching temperature T3 is preferably in the range of 50°C to 200°C. For example, the quenching temperature T3 is generally around 60°C for cold oil, around 120°C for semi-hot oil, and around 150°C for hot oil.

[0128] <Pre-chamber related processing> In the anterior chamber 2, an anterior chamber loading processor 150, an anterior chamber purge manager 152, and a carburizing chamber loading processor 156 are executed in this order. This series of processes is hereinafter defined as an anterior chamber-related process.

[0129] <Pre-chamber Loading Processing Section> 5(A) and (B), the front chamber carry-in processing section 150 opens the front chamber entrance door 22 and closes the front chamber exit door 24, and carries in the work carrier Tc (workpiece W) from the external area 1 to the front chamber 2. During the carrying-in process, outside air (oxygen, nitrogen, water) enters the front chamber 2.

[0130] In addition, the antechamber loading processing unit 150 mainly works in conjunction with the antechamber transport processing unit 110, the antechamber entrance door opening / closing processing unit 111, and the antechamber exit door opening / closing processing unit 112 to realize integrated control of processing related to the loading of the work carrier Tc (work W) into the antechamber 2.

[0131] <Front chamber purge control section> As shown in FIG. 6B, the antechamber purge management unit 152, which is executed after the antechamber loading unit 150, closes the antechamber entrance door 22 (not shown) and the antechamber exit door 24, opens the on-off valve 83 located in the degassing flow path 82 connected to the vacuum pump (negative pressure generating source) 81, and sucks out the internal gas of the antechamber 2 for 5 minutes to 30 minutes, preferably 10 minutes to 20 minutes, thereby creating a negative pressure state while discharging the invading air. The antechamber purge management unit 152 then opens the on-off valve 86 located in the purge flow path 85 connected to the purge gas source (nitrogen supply source 98) to supply purge gas (nitrogen gas) to the antechamber 2, which is in a negative pressure state, thereby restoring the antechamber 2 to normal pressure or a pressure higher than normal pressure. As a result, the antechamber 2 is filled with purge gas (nitrogen gas). Since the internal space of the antechamber 2 is at a preparation temperature T0, the workpiece W to be carried in is also maintained at the preparation temperature T0. In this embodiment, the preparation temperature T0 is the so-called room temperature (external ambient temperature), but the temperature may also be controlled by a heating device (not shown) such as a heater.

[0132] The front chamber purge management unit 152 mainly works in conjunction with the front chamber degassing unit 113 and the front chamber purge unit 114 to realize integrated control of the negative pressure state of the front chamber 2 and processing related to the purge gas.

[0133] <Carburizing chamber preparation processing section> As shown in FIG. 6(A), the carburizing chamber preparation unit 154 closes the insulated entrance door 32A and the insulated exit door 32B, and controls the on-off valve 92B of the carrier gas system 92 to supply carrier gas (nitrogen gas) to the carburizing chamber 3 through the first gas supply nozzle 941D and the second gas supply nozzle 942D, purging the carburizing chamber 3 with the carrier gas (carburizing chamber purging step). As a result, the carburizing chamber 3 is filled with purge gas (nitrogen gas). The amount of acetylene added to the carrier gas at this time is set to a lower concentration or zero than after transition to the carburizing unit described below. Note that the carburizing chamber preparation unit 154 is preferably executed simultaneously with or before the purging process of the anterior chamber purge management unit 152.

[0134] The carburizing chamber preparation processing unit 154 mainly works in conjunction with the carrier gas control unit 117 and the carburizing chamber heating unit 121 to realize integrated control of processing related to the purge gas in the carburizing chamber 3 .

[0135] <Carburizing chamber loading section> The carburizing chamber carry-in processing unit 156 is executed after the anterior chamber purge management unit 152 and the carburizing chamber preparation processing unit 154 are completed. The carburizing chamber carry-in processing unit 156 leaves the anterior chamber entrance door 22 closed, and opens the anterior chamber exit door 24 and the heat-insulated entrance door 32A as shown in FIG. 6(B). The carburizing chamber transfer device 71 (pressing device 71A) presses the workpiece carrier Tc from the anterior chamber 2 in the transfer direction H2 to move it into the carburizing chamber 3, and places the workpiece carrier Tc at the first standby position (the most upstream standby position) in the temperature rise section S1 of the carburizing chamber 3A. At this time, the nitrogen gas in the anterior chamber 2 and the nitrogen gas in the carburizing chamber 3 mix with each other. When the transfer of the workpiece carrier Tc is completed, the carburizing chamber transfer device 71 (pressing device 71A) returns to its initial state, and the anterior chamber exit door 24 and the heat-insulated entrance door 32A are closed, resulting in the state shown in FIG. 7(A). The workpiece W on the workpiece carrier Tc waiting at the first waiting position in the temperature rising section S1 is quickly heated to the carburizing temperature T1 in the temperature rising section S1 (see the time chart of the workpiece W in FIG. 3(A)).

[0136] During this time, the next workpiece carrier Tc (hereinafter referred to as the subsequent workpiece carrier) is subjected to pre-chamber-related processing in the pre-chamber 2. After the pre-chamber-related processing is completed, as shown in FIG. 7(B), the workpiece moving mechanism 72 presses the subsequent workpiece carrier Tc in the pre-chamber 2 in the transport direction H2 to move it to the carburizing chamber 3. The subsequent workpiece carrier Tc further pushes the preceding workpiece carrier Tc (hereinafter referred to as the preceding workpiece carrier) at the first standby position in the temperature-rise section S1. As a result, the subsequent workpiece carrier Tc is positioned at the first standby position in the temperature-rise section S1, and the preceding workpiece carrier Tc is shifted to the second standby position in the temperature-rise section S1. The preceding workpiece carrier Tc then undergoes temperature rise or soaking treatment at the second standby position in the temperature-rise section S1, and the subsequent workpiece carrier Tc is quickly heated to the carburizing temperature T1 at the first standby position in the temperature-rise section S1. By repeating these processes, the number of workpiece carriers Tc waiting in the temperature-rise section S1 increases.

[0137] The carburizing chamber loading processing unit 156 mainly works in conjunction with the anterior chamber entrance door opening / closing processing unit 111, the anterior chamber exit door opening / closing processing unit 112, the insulated entrance door opening / closing processing unit 115, the insulated exit door opening / closing processing unit 116, and the carburizing chamber transport control unit 119 to realize integrated control of the processes related to the transport of the workpiece carrier Tc (workpiece W) to the carburizing chamber 3.

[0138] <Carburizing Treatment Section>

[0139] When new pre-chamber-related processes are further repeated multiple times, the leading workpiece carrier Tc in the line inside the carburizing chamber 3A (hereinafter referred to as the leading workpiece carrier) moves to the fifth standby position, which is the most upstream standby position in the carburizing section S2, as shown in Figure 8(A) when the temperature rise time t1 has elapsed, calculated from the time when the leading workpiece carrier Tc is carried into the first standby position in the temperature rise section S1. As a result, the leading workpiece carrier Tc remains in the temperature rise section S1 for a total of the temperature rise time t1. When this leading workpiece carrier Tc enters the carburizing section S2, or slightly before that, the carburizing chamber preparation process unit 154 ends and the process transitions to the carburizing process unit 158.

[0140] The carburizing treatment unit 158 ​​controls the on-off valve 90B of the carburizing gas system 90 to supply a mixed gas of carrier gas (nitrogen gas) and carburizing gas (acetylene) to the carburizing chamber 3 through the first gas supply nozzle 941D and the second gas supply nozzle 942D. This performs carburizing gas supply treatment on the workpieces W accommodated in the leading workpiece carrier Tc that is positioned at the fifth standby position, which is the most upstream standby position of the carburizing section S2.

[0141] As with the carburizing chamber preparation treatment section 154, the carburizing chamber 3A is maintained at normal pressure while the carburizing treatment section 158 supplies the mixed gas. During the carburizing treatment, the flow rate per minute of the carrier gas is preferably controlled to 0.5 to 5.0 times the volume of the carburizing section S2. The flow rate of the carburizing gas is preferably controlled to 5 to 50 (L / min), taking into account the surface area of ​​the workpiece W.

[0142] Since the gas carburizing apparatus of this embodiment is a so-called continuous furnace, the supply of carburizing gas (acetylene) to the carburizing section S2 is constant during operation, as shown by the two-dot chain line in FIG. 3(B). Only the workpiece W passing through this carburizing section S2 is carburized. The supply of carburizing gas (acetylene) is continuous or intermittent. When the supply is intermittent, as shown in FIG. 3(B), the carburizing unit 158 ​​repeatedly opens the on-off valve 90B of the carburizing gas system 90 for a predetermined opening time to (e.g., 5 minutes) at a predetermined supply interval Io (e.g., 10 minutes). Note that the supply interval Io here refers to the interval between the timing at which the on-off valve 90B is opened, and does not refer to the interval between the closing of the on-off valve 90B after the opening time to and the next opening (the time the on-off valve 90B is closed). In this way, the carburizing unit 158 ​​can suppress the occurrence of excessive carburizing by supplying carburizing gas intermittently (in pulses) into the carburizing chamber 3A. At the same time, excessive supply of carbon to the workpiece W is suppressed, and the diffusion of carbon within the workpiece W is promoted, thereby reducing the occurrence of localized uneven carburizing. The occurrence of sooting can also be prevented.

[0143] When the carburizing gas is an acetylene-containing gas, the concentration of acetylene in the atmosphere in the carburizing section S2 is adjusted. Specifically, according to a demonstration experiment conducted by the inventors, the acetylene concentration in the atmosphere in the carburizing section S2 is controlled to a range of 0.10% by volume to 0.25% by volume by feedback control of the measurement results of the acetylene concentration measuring sensor 1000.

[0144] By controlling the acetylene concentration to 0.25% by volume or less, almost all of the acetylene supplied to the carburizing section S2 is adsorbed and decomposed by the workpiece W placed in the carburizing section S2, reducing the amount of excess acetylene that flows into the adjacent heating section S1 and diffusion section S3. At the same time, sooting on the surface of the workpiece W due to excess acetylene can be suppressed.

[0145] On the other hand, by controlling the acetylene concentration to 0.10% by volume or higher, the variation in carburizing can be suppressed. Note that if the acetylene concentration in the atmosphere in the carburizing section S2 is less than 0.10% by volume, acetylene shortages will occur in some locations within the carburizing section S2, which will likely result in variation in carburizing.

[0146] This "control within a range of 0.10 vol % or more to 0.25 vol % or less" will be explained in detail. For example, from the viewpoint of suppressing sooting, the process of controlling the acetylene concentration to 0.25 vol % or less may be performed so that the "average" acetylene concentration during the carburizing treatment of the workpiece W is 0.25 vol % or less. In other words, the acetylene concentration may exceed 0.25 vol % for a very short period of time during the carburizing treatment, and this includes a state in which the target control value for the acetylene concentration is set to a value of 0.25 vol % or less.

[0147] On the other hand, from the perspective of suppressing carburization variation, the process of controlling the acetylene concentration to 0.10 vol% or more means that the acetylene concentration should be controlled to 0.10 vol% or more for the amount of time required to reduce variation in the carburized layer formed on the workpiece W, and that the acetylene concentration may be controlled to less than 0.10 vol% for any excess time period. The process of controlling the acetylene concentration to 0.10 vol% or more may, for example, be controlled so that the "average" acetylene concentration during the carburization treatment of the workpiece W is 0.10 vol% or more. Similarly, this includes a state in which the target control value for the acetylene concentration is set to 0.10 vol% or more.

[0148] Furthermore, when new pre-chamber-related processes are repeatedly performed multiple times during control by the carburizing unit 158, the leading workpiece carrier Tc moves to the ninth standby position, which is the most upstream standby position in the diffusion section S3, at the timing when carburizing time t2 has elapsed counting from the time when the leading workpiece carrier Tc is carried into the fifth standby position in the carburizing section S2, as shown in Figure 8(B). As a result, the leading workpiece carrier Tc stays in the carburizing section S2 for the total carburizing time t2.

[0149] When the leading workpiece carrier Tc moves to the ninth standby position, the diffusion process for the leading workpiece carrier Tc begins. The diffusion section S3 is maintained at the carburizing temperature T1 by the overall temperature control unit 171, which has already been described, while being filled with the carrier gas (a mixed gas of carrier gas and hydrogen gas) flowing out from the carburizing section S2.

[0150] Furthermore, when new pre-chamber-related processes are repeatedly performed multiple times during control by the carburizing treatment unit 158, the leading workpiece carrier Tc moves to the thirteenth standby position, which is the most upstream standby position in the temperature decreasing section S4, at the timing when the diffusion time t3 has elapsed counting from the time when the leading workpiece carrier Tc is carried into the ninth standby position, as shown in Figure 9(A). As a result, the leading workpiece carrier Tc stays in the diffusion section S3 for a total of the diffusion time t3.

[0151] Then, during the time period when the leading workpiece carrier Tc is in the diffusion section S3, the carbon that has penetrated into the workpiece W in the carburizing section S2 diffuses appropriately, forming a hardened layer of the desired thickness (carburization depth). Then, in the temperature-reducing section S4, the temperature-reducing process for the leading workpiece carrier Tc begins.

[0152] The temperature decreasing section S4 is maintained at a preset quenching holding temperature T2 by the overall temperature management unit 171 already described.

[0153] Furthermore, when new pre-chamber related processes are repeatedly performed multiple times during control by the carburizing processing unit 158, as shown in Fig. 9(B), at the timing when the temperature drop time t4 has elapsed from the time when the leading workpiece carrier Tc is carried into the thirteenth standby position or around that timing, the "quenching chamber related processes" described in detail below are executed, and the leading workpiece carrier Tc moves from the temperature drop section S4 to the quenching chamber 4. This means that the leading workpiece carrier Tc has stayed in the temperature drop section S4 for the temperature drop time t4 in total.

[0154] Thereafter, new pre-chamber related processing and quenching chamber related processing are repeatedly performed, and the workpieces W housed in each workpiece carrier Tc lined up in the carburizing chamber 3A are processed in the same way as the workpiece W housed in the leading workpiece carrier Tc.

[0155] The carburizing unit 158 ​​cooperates with the carrier gas control unit 117 and the carburizing gas control unit 118 to realize integrated control of the carburizing process.

[0156] <Quenching chamber related processing> Next, the above-mentioned quenching chamber-related processing will be described in detail. In the quenching chamber 4, the quenching chamber main purge management unit 160, the quenching chamber carry-in processing unit 162, the quenching processing unit 164, the oil draining processing unit 166, the quenching chamber pre-purge management unit 168, and the workpiece carry-out processing unit 170 are executed in this order. This series of processing is hereinafter defined as the quenching chamber-related processing. One cycle time of this quenching chamber-related processing is the same as one cycle time of the pre-chamber-related processing.

[0157] <Quenching Room Main Purge Control Department> After the workpiece W is removed from the quenching chamber 4 by the workpiece removal processing unit 170 (described later in FIG. 13), the quenching chamber main purge management unit 160, which is executed before the quenching chamber loading processing unit 162, closes the quenching chamber entrance door 42A and the quenching chamber exit door 42B as shown in FIG. 10(A) and opens the on-off valve 87C located in the degassing flow path 87B connected to the vacuum pump (negative pressure generating source) 87A, thereby discharging the air (oxygen) that has entered the quenching chamber 4 and creating a negative pressure. The on-off valve 89B of the carrier gas system 89C is then opened. This supplies purge gas (nitrogen gas) to the quenching chamber 4 through the purge flow path 89A connected to the purge gas source (nitrogen supply source 98). The quenching chamber 4 is purged with the carrier gas, and the pressure in the quenching chamber 4 is restored to normal pressure or a higher pressure than normal pressure (quenching chamber main purge process). As a result, the quenching chamber 4 is filled with purge gas (nitrogen gas). This is called the main quenching chamber purge process. In this state, the system waits for the timing to execute the next "quenching chamber loading process section."

[0158] The quenching chamber main purge management unit 160 mainly works in conjunction with the quenching chamber entrance door opening / closing processing unit 122, the quenching chamber exit door opening / closing processing unit 123, the quenching chamber degassing processing unit 129, and the quenching chamber purge processing unit 130 to realize integrated control of the negative pressure state of the quenching chamber 4 and processing related to the purge gas.

[0159] <Hardening chamber loading section> The quenching chamber loading process unit 162, which is executed following the quenching chamber main purge management unit 160, opens the insulation exit door 32B and the quenching chamber entrance door 42A and closes the quenching chamber exit door 42B, as shown in FIG. 10(B), and moves the workpiece carrier Tc from the carburizing chamber 3 to the oil-slinging area 4A of the quenching chamber 4 using the quenching chamber transfer device 73. At this time, since both the temperature-reducing section S4 and the quenching chamber 4 are filled with nitrogen gas (carrier gas), the nitrogen gases in both spaces mix with each other. At this time, the carrier gas in the temperature-reducing section S4 contains almost no acetylene, ensuring safety. Once the workpiece carrier Tc has been moved to the quenching chamber 4, the insulation exit door 32B and the quenching chamber entrance door 42A are closed, as shown in FIG. 11(A). It is preferable that the quenching chamber loading process unit 162 be executed each time a pre-chamber-related process is performed.

[0160] The quenching chamber loading processing unit 162 mainly works in conjunction with the insulation exit door opening / closing processing unit 116, the quenching chamber entrance door opening / closing processing unit 122, the quenching chamber exit door opening / closing processing unit 123, and the quenching chamber transport control unit 124 to realize integrated control of the movement processing of the work carrier Tc (work W) to the quenching chamber 4.

[0161] <Hardening processing section> The quenching process section 164, which is executed following the quenching chamber carry-in process section 162, lowers the workpiece carrier Tc (workpiece W) temporarily placed in the oil-slinging area 4A and immerses it in oil in the oil tank 4B to rapidly cool it (quenching process), as shown in Fig. 11(B). At this time, the oil vaporizes and becomes oil smoke, which fills the quenching chamber 4. The workpiece carrier Tc (workpiece W) is immersed in the oil tank 4B for the oil quenching time.

[0162] The quenching processing unit 164 mainly works in conjunction with the lifting and lowering processing unit 125 to realize integrated control of the quenching processing.

[0163] <Oil cutting processing section> The oil-draining processing section 166, which is executed following the quenching processing section 164, performs oil-draining by lifting the work carrier Tc (workpiece W) from the oil tank 4B to the oil-draining area 4A and leaving the work carrier Tc (workpiece W) in the oil-draining area 4A for a while, as shown in Figure 12.

[0164] The oil-cutting processing unit 166 mainly works in conjunction with the lifting / lowering processing unit 125 to realize integrated control.

[0165] <Quenching room pre-purge management department> The quenching chamber pre-purge management unit 168, which is executed following the quenching processing unit 164 or oil-slinging processing unit 166, maintains the quenching chamber entrance door 42A and quenching chamber exit door 42B, which are already closed, in a closed state, as shown in FIG. 12. The gas in the quenching chamber 4 during quenching processing is sucked out by a vacuum pump (negative pressure source) 87A, creating a negative pressure while discharging the oil (oil smoke) vaporized in the nitrogen gas together with the nitrogen gas. Then, purge gas (nitrogen gas) is supplied to the quenching chamber 4, restoring the quenching chamber 4 to atmospheric pressure or a pressure higher than atmospheric pressure. This is called quenching chamber pre-purge management. As a result, the quenching chamber 4, where the workpiece carrier Tc (workpiece W) waits after the quenching process is completed, is once again filled with only purge gas (nitrogen gas). In this embodiment, the purging process for exhausting oily smoke from the quenching chamber 4 is referred to as "pre-purge," and the process of purging oxygen, hydrogen, etc. from the quenching chamber 4 with nitrogen gas before the workpiece W is transported into the quenching chamber 4 is referred to as "main purge."

[0166] The quenching chamber pre-purge management unit 168 mainly works in conjunction with the quenching chamber entrance door opening / closing processing unit 122, the quenching chamber exit door opening / closing processing unit 123, the quenching chamber degassing processing unit 129, and the quenching chamber purge processing unit 130 to realize integrated control of the negative pressure state of the quenching chamber 4 and processing related to the purge gas.

[0167] <Work removal processing section> The workpiece carrying-out processing unit 170, which is executed following the quenching chamber pre-purge management unit 168, closes the quenching chamber entrance door 42A and opens the quenching chamber exit door 42B, and carries out the workpiece carrier Tc from the quenching chamber 4 to the workpiece carrying-out area 6 by the carrying-out device 74, as shown in FIG. 13(A). After the workpiece carrier Tc has been carried out to the workpiece carrying-out area 6, the workpiece carrying-out processing unit 170 closes the quenching chamber exit door 42B and starts the next new quenching chamber-related process (quenching chamber main purge management unit 160), as shown in FIG. 13(B). It is preferable that the workpiece carrying-out processing unit 170 perform the above-mentioned processes each time a pre-chamber-related process is executed.

[0168] The workpiece carrying-out processing unit 170 mainly works in conjunction with the quenching chamber entrance door opening / closing processing unit 122, the quenching chamber exit door opening / closing processing unit 123, and the workpiece carrying-out control unit 131 to realize integrated control of the carrying-out processing of the workpiece carrier Tc (workpiece W). After the workpiece carrying-out processing unit is completed, the quenching chamber main purge management unit 160 promptly performs main purging of the quenching chamber 4 as shown in Fig. 10(A) to prepare for the carrying-in of the next workpiece W.

[0169] (fully automatic processing unit) The fully automatic processing unit 172 realizes automatic continuous operation by continuously executing the integrated management functions described above. Specifically, while executing the overall temperature management unit 171, it executes the carburizing chamber preparation processing unit 154 only at the start of operation, and then transitions to the quenching processing unit 164 for continuous operation. At the same time, it automatically repeats (loops) the pre-chamber-related processing (pre-chamber carry-in processing unit 150, pre-chamber purge management unit 152, carburizing chamber carry-in processing unit 156) and the quenching chamber-related processing (quenching chamber main purge management unit 160, quenching chamber carry-in processing unit 162, quenching processing unit 164, oil-slinging processing unit 166, quenching chamber pre-purge management unit 168, workpiece carry-out processing unit 170). This makes it possible to perform carburizing and quenching processes on the lined-up workpiece carriers Tc (workpieces W) sequentially, starting from the front, while intermittently moving the workpiece carriers Tc (workpieces W) in the transport directions H1 and H2. [Example]

[0170] The inventors of the present application carried out carburizing tests on two experimental workpieces using the gas carburizing apparatus of this embodiment. Specifically, in the time chart shown in Figure 3, the carburizing temperature T1 was set to 930°C, the quenching holding temperature T2 was set to 850°C, the temperature rise time t1 in the temperature rise treatment was 120 minutes, the carburizing time t2 in the carburizing gas supply treatment was 120 minutes, the diffusion time t3 in the diffusion treatment was 120 minutes, and the temperature fall time t4 in the temperature fall treatment was 120 minutes. Nitrogen gas was used as the carrier gas supplied to the carburizing chamber, and the flow rate was 20 (Nm 3 / Hr). In addition, acetylene-containing gas was used as the carburizing gas in the carburizing gas supply process, and its flow rate was 30 (NL / M). In the quenching process, the quenching temperature T3 was set to 170°C, and the specimen was immersed in an oil bath for 10 minutes, after which the oil was drained off.

[0171] Vickers hardness tests were conducted on each of the two carburized experimental workpieces to measure the surface hardness and cross-sectional hardness. The results are shown in Figure 14(A). It can be seen that the hardness is sufficiently high from the surface to a depth of 1 mm.

[0172] Furthermore, micrographs of cross sections near the surfaces of two experimental workpieces are shown in Figure 14(B). The micrographs include high-magnification and low-magnification ones. As shown in these micrographs, it was confirmed that good structures were obtained both near the surface and inside the experimental workpieces.

[0173] 1(A), in the gas carburizing apparatus of this embodiment, the anterior chamber 2 is formed from an airtight and / or pressure-resistant container, and the anterior chamber negative pressure generating device 80 is used to suck (degas) the gas inside the anterior chamber 2, but the present invention is not limited to this. For example, as shown in FIG. 15, a flame curtain burner 1058 may be provided below the anterior chamber entrance door 22 of the anterior chamber 2, and an exhaust hood 1055 may be placed above the anterior chamber entrance door 22. In this way, there is no need to form the anterior chamber 2 from an airtight and / or pressure-resistant container, and the anterior chamber negative pressure generating device 80 can be omitted.

[0174] Specifically, when the front chamber entrance door 22 is opened to carry the workpiece carrier Tc into the front chamber 2, the flame curtain burner 1058 is always ignited using carrier gas, carburizing gas, etc. as raw materials to form a flame curtain F. This flame curtain F burns or vaporizes the oxygen (O2) and water (H2O) contained in the outside air, preventing them from entering the front chamber 2 as they are. In other words, the workpiece carrier Tc is carried into the front chamber 2 so as to pass through the flame curtain F. Note that gases (CO2, etc.) combusted by the flame curtain burner 1058 are exhausted to the outside via the exhaust hood 1055.

[0175] When the workpiece carrier Tc is carried in and the front chamber entrance door 22 is closed, nitrogen gas is supplied to the front chamber 2 by the front chamber purge gas supply device 84, or nitrogen gas from inside the carburizing chamber 3 can be constantly introduced into the front chamber 2 through the gap in the heat-insulating entrance door (carburizing chamber entrance door) 32A. In other words, by leaking the nitrogen gas inside the front chamber 2 to the outside through the front chamber entrance door 22 of the front chamber 2, a structure is created that prevents outside air (oxygen) from entering the front chamber 2.

[0176] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the configurations and combinations thereof in the embodiments are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiments, but is limited only by the claims. [Explanation of symbols]

[0177] 1 External area 2. Front room 3 Carburizing chamber 3A Carburizing chamber 4. Quenching chamber 4A Oil drain area 4B Oil tank 5A First Connection 5B Second connecting road 6 Workpiece removal area 9. Raw material gas supply device 10 Control device 12 Heating device 16 Mixer 20A Front room entrance 20B Front chamber exit 22 Front room entrance door 23 Reciprocating drive mechanism 24 Front room exit door 25 Reciprocating drive mechanism 27 Transport path 30A Carburizing chamber entrance 30B Carburizing chamber outlet 31 Heating device 31A heater 32A Insulated entrance door 32B Insulated Exit Door 33A Reciprocating Drive Mechanism 33B Reciprocating drive mechanism 34 Mixer 36 Exhaust duct 36A On-off valve 37 Partition Wall 40 Lifting device 40A Quenching room entrance 40B Quenching chamber exit 42A Quenching room entrance door 42B Quenching chamber exit door 43 Rail 43a First supply port 44 Elevator body 44a Second supply port 45 Drive mechanism 46 Heater 47 Mixer 48 Heat exchanger 49 Mixer 49A Reciprocating Drive Mechanism 49B Reciprocating drive mechanism 70 Anteroom transport device 70A Roller Conveyor 70B hook 70C snake chain 70D drive unit 71 Carburizing chamber transport device 71A Pressing device 71B Piston rod 72 Work moving mechanism 73 Quenching chamber transport device 74 Unloading device 80 Anterior chamber negative pressure generating device 81 Vacuum Pump 82 Degassing channel 83 On-off valve 84 Front chamber purge gas supply device 85 Purge flow path 86 On-off valve 87 Hardening chamber negative pressure generating device 87A Vacuum Pump 87B Degassing channel 87C On-off valve 89 Quenching chamber purge gas supply device 89A Purge flow path 89B On-off valve 90 Carburizing gas system 90A supply pipe 90B On-off valve 90C flow meter 91 Gas Mixer 91A Supply Pipe 91B Flowmeter 92 Carrier gas system 92A Supply Pipe 92B On-off valve 92C flow meter 93 Mixer 94 Carburizing indoor supply system 96 Hydrocarbon Sources 98 Nitrogen Source 98A Gas Separator 100 control device 101 CPU 102 memory 103 Information storage medium 104 Communication Interface 110 Pre-chamber transport processing unit 111 Front room entrance door opening / closing processing unit 112 Front room exit door opening / closing processing unit 113 Front chamber degassing treatment unit 114 Front chamber purge processing section 115 Insulated entrance door opening / closing processing section 116 Insulated exit door opening / closing processing section 117 Carrier gas control section 118 Carburizing gas control unit 119 Carburizing chamber transport control unit 120 Carburizing chamber agitation processing section 121 Heat treatment section inside the carburizing chamber 122 Quenching chamber entrance door opening / closing processing section 123 Quenching chamber exit door opening / closing processing section 124 Quenching chamber transport control unit 125 Lifting processing section 126 Oil tank heater processing section 127 Oil Tank Cooling Processing Unit 128 Oil tank agitation processing section 129 Quenching chamber degassing processing section 130 Quenching chamber purge processing section 131 Work carry-out control unit 150 Front room loading processing section 152 Front chamber purge control unit 154 Carburizing chamber preparation processing section 156 Carburizing chamber loading section 158 Carburizing Treatment Section 160 Hardening Room Main Purge Control Section 162 Quenching chamber loading section 164 Hardening processing section 166 Oil cutting processing section 168 Quenching room pre-purge management department 170 Work removal processing section 171 Overall temperature control department 172 Fully automated processing unit 941 First Branch 941A Branch Pipe 941B On-off valve 941C flow meter 941D First gas supply nozzle 941E First supply port 942 Second Branch 942A Branch Pipe 942B On-off Valve 942C flow meter 942D Secondary Gas Supply Nozzle 942E Second supply port 1000 Acetylene concentration measurement sensor

Claims

1. a front room where the work is temporarily placed; a carburizing chamber, which is located downstream of the antechamber in the workpiece conveyance direction, into which carburizing gas is supplied and which performs carburizing treatment on the workpiece by heating the workpiece under atmospheric pressure or a pressure higher than atmospheric pressure; a quenching chamber that is disposed downstream of the carburizing chamber in the conveying direction and performs quenching treatment on the workpiece; a carburizing chamber transfer device that moves the workpiece from the antechamber to the carburizing chamber; a workpiece moving mechanism that moves the workpiece in the carburizing chamber in the transfer direction; a quenching chamber transfer device that moves the carburized workpiece from the carburizing chamber to the quenching chamber; a raw material gas supply device for supplying a carrier gas and the carburizing gas containing a chain unsaturated hydrocarbon that is more easily adsorbed by the workpiece than the carrier gas to the carburizing chamber; Equipped with The carburizing chamber is configured so that a plurality of workpieces can be arranged in a row in the transport direction, the workpiece moving mechanism moves all of the workpieces lined up in a row in the carburizing chamber together in the transfer direction every time the carburizing chamber transfer device transfers a workpiece from the antechamber to the carburizing chamber. Gas carburizing equipment.

2. The carburizing chamber is, from upstream to downstream, a temperature-raising section for performing a temperature-raising process to raise the temperature of the workpiece transported from the anterior chamber to a predetermined carburizing temperature; a carburizing section in which the carrier gas and the carburizing gas are supplied to the workpiece that has passed through the temperature-raising section; a diffusion section for diffusing carbon that has penetrated into the workpiece after passing through the carburizing section, thereby performing a diffusion process to form a hardened layer of a desired thickness on the workpiece; It has A workpiece can be simultaneously placed in each of the temperature-raising section, the carburizing section, and the diffusion section.

2. The gas carburizing apparatus according to claim 1.

3. the carburizing chamber has exhaust passages for exhausting gas inside the carburizing chamber on the upstream side and downstream side of the carburizing section, the exhaust of the gas through the exhaust path causes the carrier gas supplied to the carburizing section and the residual gas after carburizing the workpiece with the carburizing gas to flow into the temperature rising section and the diffusion section.

3. The gas carburizing apparatus according to claim 2.

4. The carburizing chamber comprises: a temperature-reducing section for performing a temperature-reducing process to reduce the temperature of the workpiece that has passed through the diffusion section to a preset quenching holding temperature, A workpiece can be simultaneously placed in each of the temperature-raising section, the carburizing section, the diffusion section, and the temperature-lowering section.

3. The gas carburizing apparatus according to claim 2.

5. the carrier gas comprises nitrogen; The chain unsaturated hydrocarbon contains acetylene.

2. The gas carburizing apparatus according to claim 1.

6. The concentration of the acetylene contained in the atmosphere in the carburizing chamber is 0.25% by volume or less.

6. The gas carburizing apparatus according to claim 5.

7. The concentration of the acetylene contained in the atmosphere in the carburizing chamber is 0.10% by volume or more.

6. The gas carburizing apparatus according to claim 5.

8. The workpiece moving mechanism includes: a transport path for transporting a plurality of workpieces (hereinafter referred to as a preceding workpiece row) arranged continuously in a row in the carburizing chamber; the carburizing chamber transport device; and Each time a work (hereinafter referred to as a succeeding work) is moved from the front chamber to the carburizing chamber by the carburizing chamber transport device, the row of preceding workpieces is pushed in the transport direction by the succeeding work, and moves in the transport direction.

2. The gas carburizing apparatus according to claim 1.

9. Each workpiece in the preceding workpiece row is placed at a preset standby position, the workpiece moving mechanism moves each workpiece in the preceding row of works to the adjacent standby position downstream in the transport direction each time the carburizing chamber transport device moves the subsequent workpiece from the anterior chamber to the carburizing chamber, The carburizing chamber is, from upstream to downstream, a temperature-raising section for performing a temperature-raising process to raise the temperature of the workpiece transported from the anterior chamber to a predetermined carburizing temperature; a carburizing section in which the carrier gas and the carburizing gas are supplied to the workpiece that has passed through the temperature-raising section; a diffusion section for diffusing carbon that has penetrated into the workpiece after passing through the carburizing section, and performing a diffusion process to form a hardened layer of a desired thickness on the workpiece; the temperature rising section includes a first number of the standby positions, the carburizing section includes a second number of the waiting positions; the diffusion section includes a third number of the standby positions, 9. The gas carburizing apparatus according to claim 8.

10. The second number is greater than the first number.

10. The gas carburizing apparatus according to claim 9.

11. When the time from when the previous workpiece is moved from the pre-chamber to the carburizing chamber by the carburizing chamber transport device to when the next workpiece is moved from the pre-chamber to the carburizing chamber is defined as a reference time, the time when the temperature rise treatment is performed on the workpiece in the temperature rise section is defined as a temperature rise time, the time when the carrier gas and the carburizing gas are supplied to the workpiece in the carburizing section is defined as a carburizing time, and the time when the diffusion treatment is performed on the workpiece in the diffusion section is defined as a diffusion time, the first number is expressed as a ratio of the temperature rise time to the reference time, the second number is expressed as a ratio of the carburization time to the reference time; The third number is expressed as a ratio of the diffusion time based on the reference time.

10. The gas carburizing apparatus according to claim 9.

12. the carburizing chamber has a temperature-reducing section for performing a temperature-reducing process to reduce the temperature of the workpiece that has passed through the diffusion section to a preset quenching holding temperature, The temperature decreasing section includes a fourth number of the standby positions.

10. The gas carburizing apparatus according to claim 9.

13. the quenching chamber transport device is characterized in that, every time the carburizing chamber transport device moves a workpiece from the antechamber to the carburizing chamber, the carburized workpiece lined up at the front of the line of carburizing chambers is moved to the quenching chamber.

2. The gas carburizing apparatus according to claim 1.

14. a carburizing chamber that is arranged downstream in a workpiece conveying direction from a front chamber in which the workpiece is temporarily placed, and that is arranged upstream in the conveying direction from a quenching chamber in which the workpiece is quenched, and that heats the workpiece under atmospheric pressure or a pressure higher than atmospheric pressure to carburize the workpiece; From upstream to downstream in the conveying direction, a temperature-raising section for performing a temperature-raising process to raise the temperature of the workpiece transported from the anterior chamber to a predetermined carburizing temperature; a carburizing section for performing a carburizing gas supply process in which a carrier gas and a carburizing gas are supplied to the workpiece that has passed through the temperature-raising section; a diffusion section for diffusing carbon that has penetrated into the workpiece after passing through the carburizing section, thereby performing a diffusion process to form a hardened layer of a desired thickness on the workpiece; It has within itself A workpiece can be simultaneously placed in each of the temperature-raising section, the carburizing section, and the diffusion section, a nozzle for supplying the carrier gas and the carburizing gas is disposed in the carburizing section; Carburizing chamber.

15. The furnace has exhaust passages on the upstream side and downstream side of the carburizing section for exhausting gases inside the furnace, The exhaust of the gas through the exhaust path allows residual gas remaining after the workpiece is carburized with the carburizing gas supplied to the carburizing section to flow into the temperature rising section and the diffusion section.

15. The carburizing chamber of claim 14.

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