Vacuum carburization device and vacuum carburization method

Abstract

To reduce carburization variation of workpieces carburized in the same lot when plural workpieces are simultaneously vacuum-carburized.SOLUTION: A vacuum carburization device 1 for simultaneously carburizing plural workpieces W comprises a treatment chamber 10, in which the workpieces W are inserted, and plural support bases 19 supporting the workpieces W. The treatment chamber 10 has a first side wall 13, a second side wall 14, and an insertion port 11 of the workpieces W. A first gas supply pipe 31 for emitting carburization gas is provided in a first region A1, a second gas supply pipe 32 for emitting carburization gas is provided in a second region A2, and a third gas supply pipe 33 for emitting carburization gas is provided in a third region A3. The third gas supply pipe 33 extends inward of the treatment chamber 10 from a wall opposite to a ceiling wall 16 or the insertion port 11 of the treatment chamber 10.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a vacuum carburizing apparatus and a vacuum carburizing method. [Background technology]

[0002] As an example of heat treatment to improve the wear resistance of steel automobile parts, machine parts, etc., a carburizing process is known in which carbon is dissolved in the surface of the part (hereinafter referred to as "workpiece") to harden the surface of the workpiece. Vacuum carburizing, in which carburizing is performed in a vacuum atmosphere, is also known as a carburizing method that can reduce the amount of carbon dioxide emitted from the carburizing device that performs the carburizing process.

[0003] To reduce the cost of vacuum carburizing, it is common to carry out the process using a mass production method, and it is desirable to increase the number of workpieces per lot. Patent Documents 1 and 2 disclose vacuum carburizing equipment that performs vacuum carburizing on multiple workpieces simultaneously. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5976540 [Patent Document 2] Patent No. 6817799 Summary of the Invention [Problem to be solved by the invention]

[0005] When performing carburizing treatment with a conventional vacuum carburizing apparatus, a mesh-shaped jig on which multiple workpieces are placed is loaded into a treatment chamber, and carburizing gas is discharged toward the jig from a nozzle attached to the side wall of the treatment chamber. Therefore, the carburizing gas discharged from the nozzle is first supplied to each workpiece arranged on the outer periphery of the jig.

[0006] The carburizing gas then flows from the outer periphery of the jig toward the center, but as it reaches the center of the jig, it comes into contact with the components of the jig and the workpieces, obstructing the flow of the carburizing gas. This causes the carburizing gas to be supplied unevenly to the workpieces arranged in the center of the jig, compared to the workpieces arranged in the outer periphery of the jig. As a result, the workpieces arranged in the center of the jig are more likely to suffer from uneven carburizing than those arranged in the outer periphery of the jig. In particular, when the jig has a multi-stage hierarchical structure, the flow of the carburizing gas is more likely to be obstructed, and uneven carburizing is more likely to occur.

[0007] Furthermore, when a large workpiece is placed on the jig, the carbon components in the carburizing gas are consumed by the carburizing reaction of the workpieces placed on the periphery of the jig, and the amount of carbon components in the carburizing gas that reaches the center of the jig may be insufficient. Even in this case, the workpieces placed in the center of the jig are more likely to suffer from carburizing variations than the workpieces placed on the periphery of the jig.

[0008] One possible method for reducing the variation in carburization is to increase the amount of carburizing gas discharged from a nozzle attached to the side wall of the treatment chamber, thereby supplying a large amount of carburizing gas into the treatment chamber.

[0009] However, excessive supply of carburizing gas into the treatment chamber leads to an increase in treatment costs and an increase in the frequency of sooting in the treatment chamber. When sooting occurs in the treatment chamber, burnout treatment is performed as a regular maintenance task to burn off the soot adhering to the treatment chamber. Since the workpiece cannot be carburized during burnout treatment, excessive supply of carburizing gas leads to reduced productivity.

[0010] In addition, in vacuum carburizing, pulse control is sometimes used to suppress cementite precipitation on the extreme surface of the workpiece by repeating the supply of carburizing gas and evacuation, but if the evacuation speed is slow when an excess of carburizing gas is supplied, it is easy for the carburizing gas that has not been pyrolyzed and the pyrolysis gas to coexist in the treatment chamber. In that case, if the pyrolysis gas floats near the workpiece, it becomes difficult for the carburizing gas that has not been pyrolyzed to come into contact with the workpiece, which can cause problems such as uneven carburization of the workpiece and a decrease in the carburization speed of the workpiece. To address this problem, a large vacuum pump can be used to evacuate the gas in the treatment chamber in a short time, but there is a concern that this will increase the initial cost and running cost of the equipment.

[0011] Therefore, it is not desirable to supply an excessive amount of carburizing gas as a means of reducing the variation in carburizing between workpieces placed in the center of the jig and those placed on the outer periphery of the jig. For this reason, there is room for improvement in conventional vacuum carburizing equipment in terms of reducing the variation in carburizing between workpieces carburized in the same lot.

[0012] The present invention has been made in consideration of the above circumstances, and has an object to reduce the carburization variation of workpieces carburized in the same lot when vacuum carburizing is performed on multiple workpieces simultaneously. [Means for solving the problem]

[0013] The aspects of the present invention that solve the above problems are exemplified below. (1) A vacuum carburizing apparatus for simultaneously carburizing multiple workpieces, A processing chamber into which the workpiece is loaded; A plurality of support tables for supporting the workpiece; The processing chamber includes: A first side wall; a second side wall opposite the first side wall; The workpiece is inserted into the workpiece through a work opening provided in a wall portion other than the first side wall and the second side wall. Among the plurality of support stands, the one closest to the first side wall is defined as a first support stand, the one closest to the second side wall is defined as a second support stand, a region on the first side wall side of the first support stand in the processing space formed in the processing chamber is defined as a first region, a region on the second side wall side of the second support stand is defined as a second region, and a region on the second side wall side of the first support stand and on the first side wall side of the second support stand is defined as a third region, a first gas supply pipe that discharges a carburizing gas into the first region; a second gas supply pipe that discharges the carburizing gas into the second region; a third gas supply pipe that discharges the carburizing gas to the third region is provided; 2. A vacuum carburizing apparatus, wherein the third gas supply pipe extends from a ceiling wall of the treatment chamber or a wall portion facing the supply port into the treatment chamber. (2) The vacuum carburizing apparatus described in (1), characterized in that the third gas supply pipe extends from the ceiling wall toward the inside of the treatment chamber and is provided in a plurality of pipes spaced apart in the loading direction of the workpiece. (3) The vacuum carburizing apparatus according to (1) or (2), wherein the third gas supply pipe is located at the center of the processing chamber in the width direction. (4) The third gas supply pipe is a first discharge port that discharges the carburizing gas toward the first side wall; a second discharge port for discharging the carburizing gas to the second side wall side, The vacuum carburizing apparatus according to any one of (1) to (3), wherein the end of the third gas supply pipe is closed. (5) The first discharge port and the second discharge port are each formed in a plurality of ports, The vacuum carburizing apparatus according to (4), wherein the hole diameter of each of the first discharge ports and the hole diameter of each of the second discharge ports are larger the closer they are to the tip side of the third gas supply pipe. (6) The third gas supply pipe is an inner tube to which the carburizing gas is supplied; The vacuum carburizing apparatus according to any one of (1) to (5), further comprising an outer tube that surrounds the inner tube and discharges the carburizing gas discharged from the inner tube into the treatment chamber. (7) A plurality of the third gas supply pipes are provided, A mass flow controller is connected to each of the third gas supply pipes, The vacuum carburizing apparatus according to any one of (1) to (6), further comprising a control unit for controlling the operation of each mass flow controller so that the flow rate of the carburizing gas discharged from each of the third gas supply pipes becomes a predetermined flow rate. (8) A vacuum carburizing method for simultaneously carburizing a plurality of workpieces, comprising the steps of: A vacuum carburizing method, characterized in that the carburizing treatment is performed by discharging carburizing gas to the side of a jig placed in a treatment chamber on which the workpiece is placed, and also discharging the carburizing gas from the inside of the jig onto the workpiece. Effect of the Invention

[0014] According to the present invention, when vacuum carburizing is performed on a plurality of workpieces simultaneously, it is possible to reduce the variation in carburizing of the workpieces carburized in the same lot. [Brief description of the drawings]

[0015] [Figure 1] 1 is an explanatory diagram showing a schematic configuration of a vacuum carburization apparatus according to an embodiment of the present invention. FIG. [Diagram 2] FIG. 2 is a cross-sectional view of the cross section AA of FIG. [Diagram 3] FIG. 3 is a cross-sectional view of FIG. 2 taken along line BB. [Figure 4] 4 is a cross-sectional view of a third gas supply pipe taken along the pipe axis direction. FIG. [Diagram 5] FIG. 5 is a view showing a cross section CC of FIG. [Figure 6] 13 is a diagram for explaining an arrangement region of a third gas supply pipe. FIG. [Figure 7] 13 is a diagram for explaining an arrangement region of a third gas supply pipe. FIG. [Figure 8] 13 is a diagram showing another example of the configuration of the third gas supply pipe. FIG. [Figure 9] 13 is a diagram showing another example of the configuration of the third gas supply pipe. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this specification and the drawings, elements having substantially the same functional configuration are designated by the same reference numerals, and redundant description will be omitted.

[0017] Fig. 1 is an explanatory diagram showing a schematic configuration of a vacuum carburizing apparatus according to the present embodiment, Fig. 2 is a diagram showing a cross section taken along line AA in Fig. 1, Fig. 3 is a diagram showing a cross section taken along line BB in Fig. 2.

[0018] The vacuum carburizing apparatus 1 includes a furnace body 2 and a treatment chamber 10 for performing carburizing treatment on a workpiece W made of steel parts such as automobile parts and machine parts. The treatment chamber 10 is, for example, a rectangular parallelepiped case, and is disposed inside the furnace body 2. In the drawings, the X direction is the width direction of the treatment chamber 10, the Y direction is the depth direction of the treatment chamber 10, and the Z direction is the vertical direction. The X direction, Y direction, and Z direction are perpendicular to each other. In this embodiment, the Y direction is also the loading direction of the workpiece W into the treatment chamber 10.

[0019] A loading port 11 for loading the workpiece W into the processing chamber 10 is formed in the side wall on the near side in the depth direction (negative side in the Y direction) of the four side walls of the furnace body 2 and the processing chamber 10. If the two side walls adjacent to the front side wall 12 on which the loading port 11 is formed are called the first side wall 13 and the second side wall 14, the first side wall 13 and the second side wall 14 face each other and extend parallel to the YZ plane. In other words, the loading port 11 described above is formed in a wall portion other than the first side wall 13 and the second side wall 14. The rear side wall 15 facing the front side wall 12 is a side wall that constitutes the rear side of the processing chamber 10 and extends parallel to the XZ plane.

[0020] Heat insulating materials 18 are provided on the inside of the side walls 12 to 15, the ceiling wall 16, and the bottom wall 17 of the treatment chamber 10. An openable and closable door (not shown) with heat insulating material is attached to the furnace body 2 on the charging port 11 side, and when the carburizing treatment is performed, the workpiece W is charged into the treatment chamber 10 and then the door is closed to block the charging port 11.

[0021] The heat insulating material 18 on the bottom wall 17 side is provided with a plurality of columnar support tables 19 for supporting the workpieces W. The plurality of support tables 19 are arranged at intervals along the width direction (X direction) of the processing chamber 10 and also along the loading direction (Y direction) of the workpieces W. The periphery of the lower end of each support table 19 is covered with the heat insulating material 18, and a jig 20 is placed on the upper end of each support table 19.

[0022] The jig 20 has a multi-stage hierarchical structure, with mesh-like trays arranged at intervals in the vertical direction (Z direction). The trays are connected to each other via supports, forming three stages of workpiece W placement areas, and the workpiece W is indirectly supported by the support base 19 via the jig 20.

[0023] Each of the second and third trays of the jig 20 has a gap in the center in the width direction (X direction), and the gap extends along the depth direction (Y direction) of the processing chamber 10. In other words, a groove 21 is formed in the center of the width direction of the jig 20, penetrating from the third tray of the jig 20 to the top surface of the first tray, and the groove 21 extends along the depth direction of the processing chamber 10. By having the groove 21 in the jig 20, it is possible to avoid interference between the jig 20 and a third gas supply pipe 33 described later when the jig 20 carrying the workpiece W is loaded into the processing chamber 10.

[0024] Furthermore, by having the jig 20 have the grooves 21, oil can easily flow into the grooves 21 during oil quenching, which is a process following the carburizing process, and quenching variations within a lot can be reduced compared to when a jig without the grooves 21 is used. In addition, by allowing oil to easily flow into the grooves 21, each workpiece W can be cooled more uniformly, and the amount of distortion of each workpiece caused by the quenching process can be reduced. As a result, it is possible to reduce the cost of secondary processing for distortion correction.

[0025] When the workpieces W are loaded into the processing chamber 10 using the jig 20, first, a plurality of workpieces W are placed on the jig 20, and the jig 20 is placed on the forks (not shown) of a transport device installed outside the processing chamber 10. Next, the forks move forward with the bottom surface of the jig 20 (the bottom surface of the first tray) supported by the forks, and the jig 20 moves above the support base 19. Next, the forks move down, and the jig 20 is transferred from the forks to the support base 19. Then, the forks move back with the jig 20 placed on the top surface of each support base 19, and the workpieces W placed on the jig 20 are loaded into the processing chamber 10.

[0026] The structure of the jig 20 is determined appropriately depending on the shape, size, number, etc. of the workpieces W. In addition, the structure of the jig 20 is not limited to a multi-stage hierarchical structure, and may be, for example, a tray-like or basket-like structure having only one stage in which the workpieces W are placed.

[0027] (Gas supply pipe) Next, we will explain the first gas supply pipe 31, the second gas supply pipe 32, and the third gas supply pipe 33, which supply the carburizing gas into the processing chamber 10. The carburizing gas is, for example, acetylene gas, ethylene gas, propane gas, butane gas, or a mixture of these gases.

[0028] A first gas supply pipe 31 that discharges carburizing gas to the workpiece W is provided on the first side wall 13 of the processing chamber 10. The first gas supply pipe 31 penetrates the furnace body 2 and the first side wall 13 of the processing chamber 10, and the tip of the first gas supply pipe 31 is located between the heat insulating material 18 provided on the inside of the first side wall 13 and the outer periphery of the jig 20. In addition, the end of the first gas supply pipe 31 opposite to the tip side is connected to a carburizing gas supply source (not shown) such as a cylinder in which carburizing gas is stored.

[0029] 1, a plurality of first gas supply pipes 31 are provided at intervals in the vertical direction (Z direction) in accordance with the height of each workpiece W placed on the jig 20. In addition, as shown in FIG 2, a plurality of the first gas supply pipes 31 are also provided at intervals in the depth direction (Y direction) of the processing chamber 10.

[0030] A second gas supply pipe 32 that discharges carburizing gas is provided on the second side wall 14 of the processing chamber 10. The second gas supply pipe 32 penetrates the furnace body 2 and the second side wall 14 of the processing chamber 10, and the tip of the second gas supply pipe 32 is located between the heat insulating material 18 provided on the inside of the second side wall 14 and the outer periphery of the jig 20. In addition, the end of the second gas supply pipe 32 opposite to the tip is connected to a carburizing gas supply source (not shown) such as a cylinder in which carburizing gas is stored.

[0031] 1, the second gas supply pipes 32 are provided at intervals in the vertical direction (Z direction) in accordance with the height of each workpiece W placed on the jig 20. Moreover, as shown in FIG 2, the second gas supply pipes 32 are also provided at intervals in the depth direction (Y direction) of the processing chamber 10.

[0032] A third gas supply pipe 33 that discharges carburizing gas is provided on the ceiling wall 16 of the processing chamber 10. The third gas supply pipe 33 penetrates the furnace body 2 and the ceiling wall 16 at the center in the width direction (X direction) of the processing chamber 10, and extends from the ceiling wall 16 toward the bottom of the processing chamber 10. Specifically, the third gas supply pipe 33 extends from the ceiling wall 16 to near the top surface of the first tray of the jig 20 placed on the support table 19.

[0033] In other words, the lower end of the third gas supply pipe 33 is located below half the height of the processing space S in the processing chamber 10 and above the upper ends of the multiple support stages 19. The processing space S is a region in the processing chamber 10 that is filled with the carburizing gas, and in this embodiment, the processing space S is the space inside the heat insulating material 18 arranged inside the side walls 12 to 15, the ceiling wall 16 and the bottom wall 17.

[0034] As shown in FIG. 2, the third gas supply pipes 33 are provided at intervals along the depth direction (Y direction) of the processing chamber 10, and discharge carburizing gas onto the side surface of each workpiece W lined up along the depth direction (Y direction) of the processing chamber 10.

[0035] 3, the upper end of each of the third gas supply pipes 33 is connected to a carburizing gas supply source (not shown), and a mass flow controller 34 is provided on the carburizing gas supply path of each of the third gas supply pipes 33. The operation of these mass flow controllers 34 is preferably controlled by a control unit 50 (described later) so that the flow rate supplied to each of the third gas supply pipes 33 is a predetermined flow rate. This makes it easier to uniformly supply the carburizing gas to the workpieces W placed on the outer periphery of the jig 20 and the workpieces W placed in the center of the jig 20, thereby improving the effect of reducing carburizing variations.

[0036] The above-mentioned "predetermined flow rate" is appropriately set depending on the structure of the jig 20, the shape and arrangement of the workpiece W, and the like. The flow rates of the respective third gas supply pipes 33 may be the same or different.

[0037] 4, the third gas supply pipe 33 has a shape in which the lower end is closed, and a first discharge port 35 and a second discharge port 36 are formed on the side surface of the pipe body. The first discharge port 35 is an opening for discharging the carburizing gas toward the first side wall 13 side of the above-mentioned processing chamber 10, and the second discharge port 36 is an opening for discharging the carburizing gas toward the second side wall 14 side.

[0038] The first discharge ports 35 and the second discharge ports 36 are each formed at intervals along the axial direction of the third gas supply pipe 33. As shown in Fig. 5, the first discharge ports 35 and the second discharge ports 36 are each formed at intervals along the circumferential direction of the third gas supply pipe 33.

[0039] The number and arrangement of the first discharge port 35 and the second discharge port 36 are appropriately changed depending on the structure of the jig 20 and the arrangement of the workpieces W. However, in order to more uniformly supply the carburizing gas to each of the workpieces W in the center of the jig located around the third gas supply pipe 33, it is preferable to provide at least one each of the first discharge port 35 and the second discharge port 36.

[0040] The material for the above-mentioned gas supply pipes 31 to 33 may be, for example, carbon, ceramics, stainless steel, molybdenum, tungsten, alumina, etc., but it is preferable to select alumina, which is less likely to deteriorate during burnout processing performed as a periodic maintenance operation.

[0041] The first gas supply pipe 31 to the third gas supply pipe 33 have been described above.

[0042] 2, a thermocouple 40 is provided on the first side wall 13 in the processing chamber 10 as a temperature measuring unit for measuring the temperature inside the processing chamber 10. The thermocouple 40 is inserted through the furnace body 2 and the first side wall 13, and the tip of the thermocouple 40 is located inside the heat insulating material 18 on the first side wall 13 side. A plurality of thermocouples 40 are installed at intervals along the depth direction (Y direction) of the processing chamber 10, and the temperatures of a front region, a central region, and a back region in the depth direction of the processing chamber 10 are measured.

[0043] Note that, like the first side wall 13 side, a thermocouple 40 may also be installed on the second side wall 14 side, but if the structure inside the processing chamber 10 is symmetrical, the temperature distribution in the depth direction inside the processing chamber 10 tends to be similar on the first side wall 13 side and the second side wall 14 side. Therefore, by using the temperature measurement results of the thermocouple 40 on the first side wall 13 side, it is possible to estimate the temperature distribution in the entire depth direction inside the processing chamber 10.

[0044] 1, a first heater 41 for heating the workpiece W from above the jig 20 is provided near the ceiling wall 16 in the processing chamber 10. The first heater 41 has, for example, a straight tube shape or a U-shape, and extends in the width direction (X direction) of the processing chamber 10 inside the heat insulating material 18 on the ceiling wall 16 side. The first heater 41 penetrates the first side wall 13 and the second side wall 14 and is fixed to each of the side walls 13, 14. As shown in FIG. 3, a plurality of first heaters 41 are installed at intervals along the depth direction (Y direction) of the processing chamber 10.

[0045] 1, a second heater 42 for heating the workpiece W from below the jig 20 is provided near the bottom wall 17 in the processing chamber 10. The second heater 42 has, for example, a straight tube shape or a U-shape, and extends in the width direction (X direction) of the processing chamber 10 inside the heat insulating material 18 on the bottom wall 17 side. The second heater 42 penetrates the first side wall 13 and the second side wall 14 and is fixed to each of the side walls 13, 14. As shown in FIG. 3, a plurality of second heaters 42 are installed at intervals along the depth direction (Y direction) of the processing chamber 10.

[0046] The heating elements of the heaters 41 and 42 may be made of, for example, carbon, nichrome wire, molybdenum, tungsten, silicon carbide, or the like. It is preferable to select silicon carbide (SiC), which is less likely to deteriorate during burnout processing.

[0047] In this embodiment, the heaters 41, 42 are installed so as to extend in the width direction (X direction) inside the opposing ceiling wall 16 and bottom wall 17, but the heaters 41, 42 may be installed so as to extend, for example, in the depth direction (Y direction) of the processing chamber 10. Furthermore, for example, the heaters 41, 42 may be installed so as to extend in the vertical direction (Z direction) or the depth direction (Y direction) of the processing chamber 10 inside the opposing first side wall 13 and second side wall 14.

[0048] That is, the first heater 41 can be installed in the processing chamber 10 near one of the opposing wall portions so as to extend parallel to the one wall portion, and the second heater 42 can be installed near the other wall portion so as to extend parallel to the other wall portion.

[0049] An exhaust pipe (not shown) for exhausting the atmosphere inside the processing chamber 10 is connected to the processing chamber 10, and the exhaust pipe is equipped with equipment such as a pressure gauge (not shown) and a vacuum pump (not shown).

[0050] The vacuum carburizing apparatus 1 includes a control unit 50. The control unit 50 is, for example, a computer equipped with a CPU, a memory, etc., and has a program storage unit (not shown). Various programs for controlling a series of processes performed by the vacuum carburizing apparatus 1 are stored in the program storage unit.

[0051] For example, the program storage unit stores a program for controlling the operation of the mass flow controller 34 so that the supply flow rate of the carburizing gas to the third gas supply pipe 33 becomes a predetermined flow rate, and a program for controlling the output of the first heater 41 and the second heater 42 so that the temperature distribution in the processing chamber 10 becomes a predetermined temperature distribution based on the temperatures measured by the multiple thermocouples 40. Note that these programs may be recorded in a computer-readable storage medium and installed in the control unit 50 from the storage medium.

[0052] The vacuum carburizing apparatus 1 according to this embodiment is configured as described above. In this vacuum carburizing apparatus 1, the third gas supply pipe 33 is disposed in the center in the width direction within the treatment chamber 10, and when performing the carburizing treatment, carburizing gas is discharged to each workpiece W disposed around the third gas supply pipe 33. Therefore, when performing the carburizing treatment, the carburizing gas is supplied to the workpiece W from the side of the jig 20 by the first gas supply pipe 31 and the second gas supply pipe 32, and the carburizing gas is supplied to the workpiece W from the inside of the jig 20 by the third gas supply pipe 33.

[0053] That is, with the vacuum carburizing apparatus 1, carburizing gas can be supplied even to each workpiece W placed in the center of the jig 20, where carburizing gas cannot easily reach from the sides of the jig 20. This makes it possible to supply carburizing gas from which carbon components have not been consumed to each of the workpieces W placed on the periphery of the jig 20 and the workpieces W placed in the center, thereby reducing the variation in carburizing of each workpiece W carburized in the same lot. As a result, the yield is improved and the carburizing cost can also be reduced.

[0054] In this embodiment, the third gas supply pipe 33 is provided only in the center of the processing chamber 10 in the width direction, but a plurality of third gas supply pipes 33 may be provided in the width direction (X direction) depending on the structure of the jig 20 and the arrangement of the workpieces W. Furthermore, for example, when the structure of the jig 20 is not symmetrical or when the arrangement of the workpieces W is not symmetrical, the third gas supply pipe 33 does not have to be provided in the center of the processing chamber 10 in the width direction.

[0055] In either case, the above-mentioned effect of reducing the carburizing variation can be obtained if the carburizing gas can be supplied from the inside of the jig 20 by the third gas supply pipe 33. For this reason, the arrangement area of ​​the third gas supply pipe 33 for obtaining the effect of reducing the carburizing variation is defined, for example, as follows.

[0056] (Area where the third gas supply pipe is located) 6 and 7 are diagrams for explaining the arrangement region of the third gas supply pipe 33. First, as shown in Fig. 6, of the multiple support stands 19 for placing the jig 20 thereon, the support stand closest to the first side wall 13 side is defined as the first support stand 19a, and the support stand closest to the second side wall 14 side is defined as the second support stand 19b.

[0057] Next, the area on the first side wall 13 side of the first support table 19a in the processing space S formed in the processing chamber 10 is referred to as a first area A. 1 The area closer to the second side wall 14 than the second support stand 19b is referred to as a second area A. 2 The region closer to the second side wall 14 than the first support stand 19a and closer to the first side wall 13 than the second support stand 19b is referred to as a third region A. 3 It is defined as:

[0058] From the viewpoint of reducing the above-mentioned carburization variation, the third gas supply pipe 33 is 3 The jig 20 is provided so as to extend downward from the ceiling wall 16 within the jig 20. This allows the carburizing gas to be discharged from inside the jig 20, thereby reducing the variation in carburizing of the workpieces W carburized in the same lot.

[0059] The first gas supply pipe 31 is connected to the first region A. 1 The second gas supply pipe 32 is disposed at a position where the carburizing gas can be discharged to the second region A. 2 In this way, the carburizing gas can be supplied from the side of the jig 20.

[0060] In FIG. 6, a carburizing gas is discharged from a first gas supply pipe 31 attached to the first side wall 13 into the processing chamber 10 to form a first region A. 1 For example, the first gas supply pipe 31 is connected to the first region A. 1 The first area A may be attached to the ceiling wall 16 inside the first area A. 1 When the carburizing gas is discharged downward from the first gas supply pipe 31 attached to the ceiling wall 16 of the processing chamber 10, the first region A 1The carburizing gas is discharged to the side of the jig 20, and the carburizing gas can be supplied from the side of the jig 20. For the same reason, the second gas supply pipe 32 is 2 It may also be attached to the ceiling wall 16 inside the building.

[0061] (Another configuration example of the third gas supply pipe) Next, other configuration examples of the third gas supply pipe 33 will be described.

[0062] First, the carburizing gas supplied to the third gas supply pipe 33 is supplied from the upper end side of the third gas supply pipe 33, and therefore the pressure loss increases toward the tip of the third gas supply pipe 33. Therefore, the amount of carburizing gas discharged from each of the discharge ports 35, 36 decreases toward the tip of the third gas supply pipe 33, and the amount of carburizing gas discharged varies depending on the positions of the discharge ports 35, 36 in the axial direction of the pipe.

[0063] Therefore, in order to reduce the variation in the amount of carburizing gas discharged in the axial direction of the pipe, it is preferable that the hole diameters of the first discharge port 35 and the second discharge port 36 are larger the closer they are to the tip of the third gas supply pipe 33, as shown in Fig. 8. This increases the amount of carburizing gas discharged from the discharge ports 35, 36 at the tip side of the third gas supply pipe 33, and even if pressure loss occurs inside the pipe, the variation in the amount of carburizing gas discharged from the third gas supply pipe 33 in the axial direction of the pipe can be reduced.

[0064] The third gas supply pipe 33 may have a double pipe structure as shown in Fig. 9. The third gas supply pipe 33 in the example of Fig. 9 is composed of an inner pipe 33a to which the carburizing gas is supplied, and an outer pipe 33b surrounding the inner pipe 33a. A third discharge port 37 for discharging the carburizing gas to the inside of the outer pipe 33b is formed on the side surface of the inner pipe 33a, and the above-mentioned first discharge port 35 and second discharge port 36 are formed on the side surface of the outer pipe 33b. The third discharge port 37 of the inner pipe 33a is formed at a different height from the first discharge port 35 and second discharge port 36 of the outer pipe 33b.

[0065] In the third gas supply pipe 33 having a double pipe structure, even if the amount of carburizing gas discharged from the inner pipe 33a varies due to pressure loss occurring in the inner pipe 33a, the carburizing gas discharged from the inner pipe 33a is temporarily filled in the outer pipe 33b, so that the variation in the amount of discharge is reduced. In other words, the carburizing gas is discharged from the outer pipe 33b in a state in which the variation in the amount of discharge caused by pressure loss in the inner pipe 33a is reduced, so that the carburizing gas is supplied to each workpiece more uniformly, and the effect of reducing the variation in carburizing can be improved.

[0066] In the above example, the tip of the third gas supply pipe 33 is closed, and the first discharge port 35 and the second discharge port 36 are formed on the side surface of the pipe, but the third gas supply pipe 33 may be a pipe with an open tip like a nozzle, without any discharge port on the side surface of the pipe. Even with such a third gas supply pipe, carburizing gas can be discharged from inside the jig 20 to the surrounding workpieces W, so that the carburizing variation of the workpieces W carburized in the same lot can be reduced compared to a vacuum carburizing apparatus of a conventional structure in which carburizing gas cannot be discharged from inside the jig.

[0067] Furthermore, in the above example, multiple third gas supply pipes 33 were provided at intervals in the depth direction (Y direction) within the processing chamber 10, but only one third gas supply pipe 33 may be provided. Even in this case, it is possible to reduce the carburizing variation of the workpieces W carburized in the same lot, compared to a vacuum carburizing apparatus of a conventional structure in which the carburizing gas cannot be discharged from inside the jig.

[0068] However, when a large number of workpieces W are carburized in the same lot, a plurality of workpieces W are arranged side by side along the depth direction of the jig 20. For this reason, from the viewpoint of supplying the carburizing gas to each workpiece W more uniformly, it is preferable to provide a plurality of third gas supply pipes 33 along the depth direction within the treatment chamber 10.

[0069] Furthermore, in the above example, the third gas supply pipe 33 is disposed so as to extend from the ceiling wall 16 of the processing chamber 10 to the inside of the processing chamber 10, but the third gas supply pipe 33 may be disposed so as to extend, for example, from the rear side wall 15 of the processing chamber 10 to the inside of the processing chamber 10. Even when the third gas supply pipe 33 is installed on the rear side wall 15, the carburizing gas can be discharged from the inside of the jig 20 to the workpieces W around the third gas supply pipe 33, thereby obtaining the effect of reducing the carburizing variation of the workpieces W carburized in the same lot.

[0070] Although the embodiment of the present invention has been exemplified above, the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention.

[0071] For example, the components of the above-described embodiments may be combined in any manner. Any combination will naturally provide the functions and advantages of each of the components in the combination, and will also provide other functions and advantages that will be apparent to those skilled in the art from the description of this specification.

[0072] In addition, the effects described in this specification are merely explanatory or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that are apparent to a person skilled in the art from the description of this specification in addition to or in place of the above effects. [Industrial Applicability]

[0073] The present invention can be applied to a vacuum carburizing apparatus for a workpiece, and can also be applied to other heat treatment apparatuses, such as a gas carburizing apparatus and a nitriding apparatus. [Explanation of symbols]

[0074] 1 Vacuum carburizing equipment 2 Furnace body 10 Processing Room 11 Charging port 12 Front side wall 13 First side wall 14 Second side wall 15 Rear side wall 16 Ceiling Wall 17 Bottom wall 18 Insulation 19 Support stand 19a 1st support stand 19b 2nd support stand 20 Jig 21 Groove 31 First gas supply pipe 32 Second gas supply pipe 33 Third Gas Supply Pipe 33a inner tube 33b outer tube 34 Mass Flow Controller 35 1st discharge port 36 2nd outlet 37 Third discharge port 40 Thermocouple 41 First heater 42 Second heater 50 Control section A 1 1st area A 2 2nd area A 3 Third area W work

Claims

1. A vacuum carburizing apparatus for simultaneously carburizing multiple workpieces, A processing chamber into which the workpiece is loaded; A plurality of support tables for supporting the workpiece; The processing chamber includes: A first side wall; a second side wall opposite the first side wall; The workpiece is inserted into the workpiece through an inlet provided in a wall portion other than the first side wall and the second side wall. Among the plurality of support tables, the support table closest to the first side wall is defined as a first support table, and the support table closest to the second side wall is defined as a second support table. A region on the first side wall side of the first support table in the processing space formed in the processing chamber is defined as a first region, a region on the second side wall side of the second support table is defined as a second region, and a region on the second side wall side of the first support table and on the first side wall side of the second support table is defined as a third region, a first gas supply pipe that discharges a carburizing gas into the first region; a second gas supply pipe that discharges the carburizing gas into the second region; a third gas supply pipe that discharges the carburizing gas to the third region is provided; 2. A vacuum carburizing apparatus, wherein the third gas supply pipe extends from a ceiling wall of the treatment chamber or a wall portion facing the supply port toward the inside of the treatment chamber.

2. 2. The vacuum carburizing apparatus according to claim 1, wherein the third gas supply pipe extends from the ceiling wall to the inside of the treatment chamber, and a plurality of the third gas supply pipes are provided at intervals in the loading direction of the workpiece.

3. 3. The vacuum carburizing apparatus according to claim 1, wherein the third gas supply pipe is located at a center portion in a width direction of the processing chamber.

4. The third gas supply pipe is a first discharge port that discharges the carburizing gas toward the first side wall; a second discharge port for discharging the carburizing gas to the second side wall side, 3. The vacuum carburizing apparatus according to claim 1, wherein a tip of the third gas supply pipe is closed.

5. The first discharge port and the second discharge port are each formed in a plurality of numbers, 5. The vacuum carburizing apparatus according to claim 4, wherein the hole diameter of each of the first discharge ports and the hole diameter of each of the second discharge ports are larger the closer they are to a tip end side of the third gas supply pipe.

6. The third gas supply pipe is an inner tube to which the carburizing gas is supplied; 5. The vacuum carburizing apparatus according to claim 4, further comprising: an outer pipe surrounding said inner pipe and discharging said carburizing gas discharged from said inner pipe into said treatment chamber.

7. A plurality of the third gas supply pipes are provided, A mass flow controller is connected to each of the third gas supply pipes, 3. The vacuum carburizing apparatus according to claim 1, further comprising a control unit for controlling the operation of each mass flow controller so that the flow rate of the carburizing gas discharged from each of the third gas supply pipes becomes a predetermined flow rate.

8. A vacuum carburizing method for simultaneously carburizing a plurality of workpieces, comprising the steps of: A vacuum carburizing method, characterized in that carburizing gas is discharged to the side of a jig placed in a treatment chamber on which the workpiece is placed, and the carburizing gas is also discharged from inside the jig onto the workpiece, thereby carrying out the carburizing treatment.

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