JP4547664B2 - Vacuum carburizing furnace and carburizing gas exhaust method - Google Patents

Description

  The present invention relates to a vacuum carburizing furnace, and more particularly to a method for exhausting carburizing gas during vacuum carburizing treatment of steel materials and a vacuum carburizing furnace therefor.

  In the vacuum carburizing process, a steel material is placed in a heating chamber depressurized by a vacuum pump, and the temperature is raised by a heater. Hold until each part of the steel material reaches a predetermined carburizing temperature. When the temperature becomes uniform, the carburizing gas is sucked and exhausted from the heating chamber by a vacuum pump while introducing the carburizing gas into the heating chamber by the gas introduction nozzle, and the steel material is carburized. At this time, a large amount of carburizing gas is used to sufficiently carburize the steel material.

A hydrocarbon-based gas is used as the carburizing gas, but the unit price is generally high. Therefore, a method for reducing the amount of carburizing gas used is desired.
For this reason, in Patent Document 1, in order to reduce the carburizing gas to be used, the carburizing gas containing hydrogen and nitrogen is introduced outside the heating chamber by introducing the carburizing gas only into the heating chamber partitioned by the heat insulating material. A method of introducing a gas other than the above is disclosed.
JP2004-43948 JP2003-183807

  However, conventionally, carburizing gas is generally exhausted using one exhaust port (for example, Patent Document 1). The flow direction of the carburizing gas in the furnace is fixed for evacuation by one exhaust port. For this reason, the density of the carburizing gas in the heating chamber, that is, a concentration difference occurs, and the carburizing quality of the material to be treated such as steel material varies.

In order to cope with this, in Patent Document 2, a large number of gas supply ports are provided in a carburizing chamber which is a heating chamber, and a plurality of suction ports are formed in an exhaust pipe extending into the heating chamber. Furthermore, since the material to be treated is disposed between the gas supply port and the suction port, the carburizing gas is allowed to act evenly and sufficiently on the material to be treated.
However, in the method of Patent Document 2, since the flow direction of the carburizing gas is constant, the position of the material to be treated exposed to the carburizing gas flow does not change, and the position exposed to the carburizing gas flow and the position not exposed. There is a possibility that the carburization will be uneven between.

  Accordingly, an object of the present invention is to reduce the amount of carburizing gas used by changing the flow of the carburizing gas, and at the same time, carburizing in a vacuum carburizing furnace and a vacuum carburizing furnace capable of making the carburizing of the material to be treated more uniform. A gas exhaust method is provided.

According to the reference example , a hollow heating chamber that accommodates the material to be vacuum carburized therein, a heater that is located in the heating chamber and that heats the material to be treated, and a carburizing gas introduction that introduces a carburizing gas into the heating chamber A pipe, a vacuum pump for sucking and exhausting the gas in the heating chamber, a plurality of gas exhaust pipes communicating with the vacuum pump and the heating chamber, and an exhaust pipe selecting means for alternately opening the gas exhaust pipe A vacuum carburizing furnace is provided.

  With this configuration, since the exhaust pipe to be opened is alternately switched by the exhaust pipe selection means, the direction of the gas flow is changed so that the carburizing gas in the heating chamber is sucked into the switched exhaust pipe. Therefore, since the position of the material to be treated exposed to the flow of the carburizing gas changes, the material to be treated can be carburized more uniformly.

According to a preferred embodiment of the reference example, the vacuum carburizing furnace includes a plurality of the gas introduction pipes and includes gas introduction pipe selection means for alternately opening the gas introduction pipes.
With this configuration, a plurality of gas introduction pipes are provided, and the gas introduction pipe opened by the gas introduction pipe selection means is switched to switch the position for introducing the carburizing gas. The position of the workpiece to be exposed to the gas flow changes. Therefore, the material to be treated can be carburized more uniformly.

According to a preferred embodiment of the reference example , each of the gas introduction pipes has a gas introduction opening that opens into the heating chamber, and the gas introduction pipes face each other with the material to be processed in the heating chamber interposed therebetween. To be arranged.
With this configuration, the gas inlets face each other with the material to be processed in the heating chamber interposed therebetween, so that the carburizing gas is alternately introduced from both sides of the material to be processed by switching the gas introduction pipe to be opened. As a result, the carburization of the material to be treated can be made more uniform.

According to a preferred embodiment of the reference example , each of the exhaust pipes has an exhaust port that opens into the heating chamber, and the exhaust pipe faces each other with the material to be processed in the heating chamber interposed therebetween. Be placed.
With this configuration, the exhaust ports are opposed to each other with the material to be processed in the heating chamber interposed therebetween, so that the carburizing gas is alternately sucked from both sides of the material to be processed by switching the exhaust pipe to be opened. The carburization of the material to be treated can be made more uniform.

According to another reference example , a hollow heating chamber that accommodates a material to be vacuum carburized therein, an airtight container placed in the heating chamber, and an outside of the airtight container in the heating chamber. A heater for heating a material to be processed, a carburizing gas introduction pipe for introducing a carburizing gas into the hermetic container, a vacuum pump for sucking and exhausting the gas in the hermetic container, and the vacuum pump and the hermetic container There is provided a vacuum carburizing furnace comprising a plurality of gas exhaust pipes communicating with each other and exhaust pipe selection means for alternately opening the gas exhaust pipes.

  With this configuration, the exhaust pipe that opens as described above is alternately switched by the exhaust pipe selection means, and the position of the material to be treated that is exposed to the flow of the carburizing gas changes, so that the material to be treated can be carburized more uniformly. it can. Further, since the carburizing gas is introduced into the airtight container and directly exhausted from the airtight container, it is possible to prevent the carburizing gas from leaking out of the airtight container. It is possible to prevent deterioration of the insulation resistance of the part.

Further , according to another reference example , a hollow heating chamber that accommodates a material to be vacuum carburized therein, a heater that is located in the heating chamber and heats the material to be treated, and a carburizing gas is introduced into the heating chamber. A carburizing gas introduction pipe, a vacuum pump for sucking and exhausting gas in the heating chamber, a gas exhaust pipe communicating with the vacuum pump and the heating chamber, and a material to be processed accommodated in the heating chamber. There is provided a vacuum carburizing furnace comprising a workpiece rotating means for processing.

According to this reference example , the direction of the material to be treated is changed by the material rotation means while the material to be treated is carburized in the heating chamber, so that the position of the material to be exposed to the flow of the carburizing gas changes. The material to be treated can be carburized more uniformly.

Further, according to another reference example , there is provided a method for exhausting a carburizing gas introduced into a heating chamber of a vacuum carburizing furnace, and in order to carburize a material to be processed placed in a heating chamber under reduced pressure, There is provided a carburizing gas exhaust method characterized by introducing a carburizing gas and switching a position in the heating chamber for sucking and exhausting the carburizing gas introduced into the heating chamber.

As a result, the position of suctioning and exhausting the carburizing gas in the heating chamber is switched, so that the flow of the carburizing gas changes, the position of the material to be treated exposed to the carburizing gas flow changes, and the material to be treated becomes more uniform. Can carburize
According to the present invention, a hollow heating chamber that accommodates a workpiece to be vacuum carburized therein, a heater that is located in the heating chamber and that heats the workpiece, and a carburizing gas introduction that introduces a carburizing gas into the heating chamber. A pipe, a vacuum pump for sucking and exhausting the gas in the heating chamber, first, second, third and fourth gas exhaust pipes communicating with the vacuum pump and the heating chamber, and the first and second And an exhaust pipe selection means for sequentially opening the third and fourth gas exhaust pipes one by one, each of the gas exhaust pipes having an exhaust opening that opens into the heating chamber, and the first gas exhaust The exhaust port of the pipe is located on one side in the first direction, the exhaust port of the second gas exhaust pipe is located on the other side in the first direction, and the material to be treated is located between these one side and the other side. The exhaust port of the third gas exhaust pipe is located on one side of the second direction orthogonal to the first direction, Outlet of the scan exhaust pipe is located on the other side in the second direction, wherein the workpiece is located between these one side and the other side, a vacuum carburizing furnace is provided, characterized in that.
In addition, according to the present invention, a hollow heating chamber that houses a material to be vacuum carburized therein, a heater that is located in the heating chamber and heats the material to be processed, and a first gas for introducing carburizing gas into the heating chamber is provided. , Second, third and fourth carburizing gas introduction pipes, a vacuum pump for sucking and exhausting gas in the heating chamber, a gas exhaust pipe communicating the vacuum pump and the heating chamber, first, first Gas introduction pipe selection means for sequentially opening the second, third, and fourth gas introduction pipes one by one, each of the gas introduction pipes having a gas introduction opening that opens into the heating chamber. The gas inlet of the gas inlet pipe is located on one side in the first direction, and the gas inlet of the second gas inlet pipe is located on the other side in the first direction, between these one side and the other side. The material to be treated is located, and the gas introduction port of the third gas introduction pipe is one in the second direction orthogonal to the first direction. The gas introduction port of the fourth gas introduction pipe is located on the other side in the second direction, and the material to be treated is located between the one side and the other side. A carburizing furnace is provided.
Furthermore, according to the present invention, a hollow heating chamber that accommodates a workpiece to be vacuum carburized therein, a heater that is positioned in the heating chamber and that heats the workpiece, and a carburizing gas that introduces a carburizing gas into the heating chamber. A gas introduction pipe, a vacuum pump for sucking and exhausting the gas in the heating chamber, and first, second, third and fourth gas exhaust pipes for communicating the vacuum pump and the heating chamber, Each gas exhaust pipe has an exhaust opening that opens into the heating chamber, the exhaust outlet of the first gas exhaust pipe is located on one side in the first direction, and the exhaust outlet of the second gas exhaust pipe is the first outlet. Located on the other side of the direction, the material to be treated is located between the one side and the other side, and the exhaust port of the third gas exhaust pipe is located on one side of the second direction orthogonal to the first direction The exhaust port of the fourth gas exhaust pipe is located on the other side in the second direction, and between these one side and the other side. A carburizing gas is introduced into the heating chamber in order to carburize the processing material placed in the heating chamber under reduced pressure, and the first, second, third and fourth gases are located. There is provided a vacuum carburizing method characterized by opening exhaust pipes one by one in order.
In addition, according to the present invention, a hollow heating chamber that houses a material to be vacuum carburized therein, a heater that is located in the heating chamber and heats the material to be processed, and a first gas for introducing carburizing gas into the heating chamber is provided. The second, third and fourth carburizing gas introduction pipes, a vacuum pump for sucking and exhausting the gas in the heating chamber, and a gas exhaust pipe for communicating the vacuum pump and the heating chamber, Each gas introduction pipe has a gas introduction opening that opens into the heating chamber, the gas introduction opening of the first gas introduction pipe is located on one side in the first direction, and the gas introduction opening of the second gas introduction pipe Is located on the other side of the first direction, the material to be treated is located between the one side and the other side, and the gas inlet of the third gas introduction pipe is in the second direction orthogonal to the first direction. Located on one side, the gas introduction port of the fourth gas introduction pipe is located on the other side in the second direction. The first, second, third and fourth carburizing gas introduction pipes are used for carburizing the material to be treated which is located between the first side and the other side and which is placed in the heating chamber under reduced pressure. A vacuum carburizing method is provided, in which the carburizing gas is introduced into the heating chamber one by one, and the carburizing gas is exhausted from the gas exhaust pipe.

  While the carburizing material is being carburized, the position of suctioning and exhausting the carburizing gas in the heating chamber is switched, so that the flow direction of the carburizing gas is changed. Thereby, unlike the case where the position for sucking and exhausting the gas is fixed, the time-averaged density of the carburizing gas in the heating chamber becomes more uniform, and the position of the workpiece to be exposed to the flow of the carburizing gas is Since it changes, a to-be-processed material can be carburized more uniformly.

Furthermore, in the past, in order to reduce the variation in the carburization of the material to be treated, the carburizing gas was excessively supplied. However, in the present invention, the position of the carburizing gas can be changed by switching the position where the gas is sucked and exhausted as described above. The amount used is minimized and the consumption of carburizing gas can be reduced.
Moreover, since excessively carburizing gas causes excessive carburization of the material to be treated, an effect of suppressing excessive carburization can be obtained by reducing the amount of carburizing gas used.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the overlapping description is abbreviate | omitted and the same code | symbol is attached | subjected to a common or corresponding part in each figure.

FIG. 1 shows a vacuum carburizing furnace 10 according to Reference Example 1 . A vacuum carburizing furnace 10 in FIG. 1 includes a furnace body 2, a heat insulating material 6 that defines a heating chamber 4 that is hollow inside and has an open / close door (not shown), and a heater 8 that is provided in the heating chamber 4. The heater 8 may be a heater suitable for Reference Example 1 such as an electric heater or a radiant tube heater. In Reference Example 1 , a gas introduction nozzle 12 having a gas introduction port that opens in the heating chamber 4 at the tip is provided. The carburizing gas is supplied from a carburizing gas supply source, and is introduced into the heating chamber 4 from a gas introducing port of the gas introducing nozzle 12 through a carburizing gas introducing pipe (not shown).

According to the first reference example, the exhaust pipe 16 a having an exhaust port opened in the upper part of the heating chamber 4 and the exhaust pipe 16 b having an exhaust port opened in the lower part of the heating chamber 4 are provided. In the example of FIG. 1, the exhaust port of the exhaust pipe 16 a and the exhaust port of the exhaust pipe 16 b are located at the upper and lower portions in the heating chamber 4 so as to face each other so as to sandwich a material to be processed such as a steel material. Yes. Each of these two exhaust pipes 16 a and 16 b communicates the inside of the heating chamber 4 with the vacuum pump 17. Thereby, the vacuum pump 17 sucks and exhausts the gas in the heating chamber 4 from the upper and lower exhaust ports in the heating chamber 4 formed in each of the two exhaust pipes 16a and 16b, and decompresses the heating chamber 4.

  As shown in FIG. 1, the exhaust pipe 16a is provided with an on-off valve 18a, and the exhaust pipe 16b is provided with an on-off valve 18b. Furthermore, the control part 19 which sends a control signal to these on-off valves 18a and 18b and controls opening and closing of the on-off valves 18a and 18b is provided.

  While the carburizing gas is introduced from the gas inlet of the gas inlet nozzle 12 into the heating chamber 4 decompressed by the vacuum pump 17 and the workpiece 1 is carburized, the control unit 19 includes an on-off valve. A control signal is sent to 18a and 18b, and the two on-off valves 18a and 18b are alternately opened and closed, and the exhaust pipes 16a and 16b are alternately opened and closed. Opening and closing the exhaust pipe or the carburizing gas introduction pipe means that the gas can pass through or cannot pass through the exhaust pipe or the carburizing gas introduction pipe. For example, as shown in FIG. 2, first, only the first on-off valve 18a is opened, and the second on-off valve 18b is closed. When a predetermined time has elapsed, the first on-off valve 18a is closed and the second on-off valve 18b is opened. In this manner, the opening / closing of the on-off valves 18a and 18b is alternately switched. That is, the exhaust port for sucking and exhausting the inside of the heating chamber 4 is alternately switched between the exhaust port of the upper exhaust pipe 16a and the exhaust port of the lower exhaust pipe 16b. These on-off valves 18a and 18b and the control unit 19 constitute exhaust pipe selection means. In addition, you may use the other appropriate thing which can switch an exhaust pipe as an exhaust pipe selection means.

  As a result, the exhaust ports to be used are alternately switched. For example, the carburizing gas in the heating chamber 4 is directed toward the upper exhaust port by first sucking and exhausting only from the exhaust port of the upper exhaust pipe 16a. Next, the used exhaust port is switched to the exhaust port of the lower exhaust pipe 16 b, so that the carburizing gas in the heating chamber 4 flows toward the lower exhaust port 16. By alternately switching the exhaust pipes used in this way, that is, the exhaust ports, the flow direction of the carburizing gas changes, and the gas density in the heating chamber 4 becomes more uniform when time-averaged. By changing the position of the material 1 to be exposed to the flow, the material 1 can be carburized more uniformly.

Next, a first embodiment of the present invention will be described. FIG. 3 shows a vacuum carburizing furnace 20 according to the first embodiment. Hereinafter, differences from Reference Example 1 will be mainly described.

In FIG. 3, as in Reference Example 1 , a heater 8 is provided in the heating chamber 4, and a plurality of gas introduction nozzles 12 having gas introduction ports that open into the heating chamber 4 are provided in the heating chamber.

According to the first embodiment, four exhaust pipes 16 a, 16 b, 16 c and 16 d having exhaust ports opened in the heating chamber 4 are provided. In the example of FIG. 4, the upper and lower exhaust pipes 16 a and 16 b are positioned at the upper and lower portions in the heating chamber 4 so as to face each other, and the left and right exhaust pipes 16 c and 16 d It is located on the left and right in the heating chamber 4 so as to face each other. Each of the exhaust pipes 16a, 16b, 16c, and 16d communicates the inside of the heating chamber 4 with the vacuum pump 17. The vacuum pump sucks and exhausts the gas in the heating chamber 4 from the exhaust ports formed in the exhaust pipes 16a, 16b, 16c, and 16d.

  As shown in FIG. 3, the exhaust pipes 16a, 16b, 16c, and 16d are provided with on-off valves 18a, 18b, 18c, and 18d, respectively. Further, control signals are sent to these on-off valves 18a, 18b, 18c, 18d to control the opening / closing of the first on-off valve 18a, the second on-off valve 18b, the third on-off valve 18c, and the fourth on-off valve 18d. A control unit 19 is provided.

  While the carburizing gas is being introduced into the heating chamber 4, which is decompressed by the vacuum pump 17, and carburizing the workpiece 1, the control unit 19 includes the on-off valves 18 a, 18 b, 18 c, A control signal is sent to 18d to control the opening and closing of the four on-off valves 18a, 18b, 18c and 18d. For example, as shown in FIG. 4, only the first opening / closing valve 18a is opened first, only the second opening / closing valve 18b is opened after a predetermined time, and then the third opening / closing valve 18c is opened after a predetermined time. Only after a predetermined time, only the fourth on-off valve 18d is opened. By switching the open / close valves that are sequentially opened in this way, the exhaust pipes 16a, 16b, 16c, and 16d used for sucking and exhausting the gas in the heating chamber 4, that is, the exhaust ports are sequentially switched. These on-off valves 18a, 18b, 18c, 18d and the control unit 19 constitute an exhaust pipe selection means. In addition, you may use the other appropriate thing which can switch an exhaust pipe as an exhaust pipe selection means.

  As a result, the exhaust ports to be used are sequentially switched, so that the flow direction of the carburizing gas changes toward the switched exhaust port, and the gas density in the heating chamber 4 is made more uniform, so that the carburizing gas is used. By changing the position of the workpiece 1 exposed to the gas flow, the workpiece 1 can be carburized more uniformly.

FIG. 5 shows a vacuum carburizing furnace 30 according to Reference Example 2 . The vacuum carburizing furnace 30 of FIG. 5 is obtained by applying an airtight container 22 to the vacuum carburizing furnace 10 of Reference Example 1 shown in FIG. In the following, differences between the reference example 2 and the reference example 1 will be mainly described.

  The vacuum carburizing furnace 30 in FIG. 5 is provided with an airtight container 22 in which the workpiece 1 is accommodated. The airtight container 22 may be, for example, a box type having an openable / closable blocking door or a lid, and the internal airtightness is maintained with the blocking door closed. The workpiece 1 can be accommodated in the airtight container 22 or taken out from the airtight container 22 by opening and closing the shut-off door. The airtight container 22 is made of a material having airtightness such as graphite or a metallic material. Moreover, you may make from other suitable materials which have airtightness other than a graphite and a metallic material.

  The heater 8 is provided outside the airtight container 22 in the heating chamber 4 and heats the inside of the airtight container 22 when carburizing the material 1 to be processed in the airtight container 22. In the vacuum carburizing furnace 30 of FIG. 5, the gas is introduced into the airtight container 22 through a gas introduction port formed at the tip of the gas introduction nozzle 12 and opening into the airtight container 22. Further, exhaust pipes 16 a and 16 b having exhaust ports opened in the airtight container 22 are provided. With this configuration, the gas in the airtight container 22 is sucked and exhausted from the exhaust ports of the exhaust pipes 16a and 16b by the vacuum pump 17, the pressure in the heating chamber 4 is reduced, and the carburizing gas supplied from a carburizing gas supply source (not shown). Is introduced into the airtight container 22 from the gas introduction port of the gas introduction nozzle 12.

As a result, the workpiece 1 in the airtight container 22 is carburized. At this time, as in the first reference example , the control unit 19 alternately opens and closes the open / close valves 18a and 18b, and the exhaust pipe 16a, 16b is alternately opened and closed. Thereby, the exhaust port which sucks and exhausts the carburizing gas in the heating chamber 4 can be switched alternately. Accordingly, since the exhaust ports to be used are sequentially switched, the flow direction of the carburizing gas is alternately changed to be directed to the switched exhaust port, and the time-averaged gas density in the heating chamber 4 is made more uniform. And the to-be-processed material 1 can be carburized more uniformly by changing the position of the to-be-processed material 1 exposed to the flow of the gas for carburizing.

Further, according to Reference Example 2 , in order to carburize the material 1 to be processed, the material 1 is accommodated in the airtight container 22 and the carburizing gas is introduced only into the airtight container 22 whose pressure is reduced. Since the carburizing gas is exhausted directly from the inside of the airtight container 22, it is possible to prevent the carburizing gas from leaking to the outside of the airtight container 22. Therefore, it is possible to prevent deterioration of the insulation resistance of the electrode portion of the heater 8 due to the leaked carburizing gas.

In Reference Example 2 , the airtight container 22 is applied to the vacuum carburizing furnace 10 of Reference Example 1, but the present invention is not limited to this. For example, you may apply the airtight container 22 to 1st Embodiment, 2nd Embodiment mentioned later, or the reference example 3. FIG. In this case, the gas introduction port of the gas introduction nozzle 12 opens the carburizing gas into the airtight container 22 instead of the heating chamber, and the exhaust port formed in the exhaust pipe replaces the inside of the heating chamber 4. The airtight container 22 is opened. The carburizing gas is introduced only into the airtight container 22 by the gas introduction nozzle 12, and the vacuum pump 17 sucks and exhausts the carburizing gas from the airtight container 22 directly from the exhaust port of the exhaust pipe.

FIG. 6 is a view showing a vacuum carburizing furnace 40 according to the second embodiment of the present invention. In the example of FIG. 6, a plurality of gas introduction nozzles 12 having gas introduction ports opened in the heating chamber 4 are provided. In addition, an exhaust pipe 16 a having an exhaust port opening in the upper part of the heating chamber 4 and an exhaust pipe 16 b having an exhaust port opening in the lower part of the heating chamber 4 are provided. The gas in the heating chamber 4 is sucked and exhausted from the exhaust ports of the exhaust pipes 16a and 16b through the exhaust pipes 16a and 16b by a vacuum pump (not shown), and the inside of the heating chamber 4 is decompressed.

  In addition, gas introduction nozzles 12 a, 12 b, 12 c, and 12 d having gas introduction ports opened in the heating chamber 4 are provided. Further, as shown in FIG. 6, carburizing gas introduction pipes 15 a, 15 b, 15 c, and 15 d that allow the gas introduction nozzles 12 a, 12 b, 12 c, and 12 d to communicate with the carburizing gas supply source 14 are provided. Further, a first on-off valve 23a, a second on-off valve 23b, a third on-off valve 23c, and a fourth on-off valve 23d are provided in each of the carburizing gas introduction pipes 15a, 15b, 15c, and 15d. Furthermore, the control part 19 which sends a control signal to the on-off valve 23 and controls opening / closing of these on-off valves 23 is provided. The on-off valves 23a, 23b, 23c, and 23d and the control unit 19 constitute a gas introduction pipe selection unit. In addition, you may use the other suitable thing which can switch a gas introduction pipe | tube as a gas introduction pipe | tube selection means.

According to the second embodiment, the control of the control unit 19 is performed while the carburizing gas 1 is being carburized by introducing the carburizing gas from the gas inlet 12 into the heating chamber 4 that has been decompressed by the vacuum pump 17. By the signal, for example, as shown in FIG. 4 described above, the open / close valves 23a, 23b, 23c, and 23d to be opened are sequentially switched. As a result, the carburizing gas introduction pipes 15a, 15b, 15c, and 15d are alternately opened, so that the gas introduction nozzle for introducing the carburizing gas into the heating chamber is switched, and the introduction position of the carburizing gas is changed. The flow direction of the working gas is changed, the time average gas density in the heating chamber 4 is made more uniform, and the position of the workpiece 1 exposed to the carburizing gas flow is changed, so that the treatment is performed more uniformly. The material 1 can be carburized.

Next, a vacuum carburizing furnace 50 according to Reference Example 3 will be described with reference to FIG.

  In the vacuum carburizing furnace 50 of FIG. 7, gas introduction nozzles 12 a, 12 b, and 12 c having gas introduction openings opened on the upper, lower, and side surfaces in the heating chamber 4 are provided. In addition, exhaust pipes 16 a and 16 b having exhaust ports that are opened in the upper and lower portions of the heating chamber 4 are provided.

In Reference Example 3 , as shown in FIG. 7, a first on-off valve 18 a for opening and closing an exhaust pipe 16 a having an exhaust port opened at the upper part in the heating chamber 4 and an opening at the lower part in the heating chamber 4 are provided. And a second opening / closing valve 18b for opening / closing an exhaust pipe 16b having an exhaust port. Each of the exhaust pipes 16 a and 16 b communicates the inside of the heating chamber and the vacuum pump 17. Thereby, the vacuum pump 17 sucks and exhausts the gas in the heating chamber 4 through the exhaust pipes 16a and 16b, and depressurizes the heating chamber.

  In the vacuum carburizing furnace 50 of FIG. 7, the carburizing gas supplied from the carburizing gas supply source 14 is introduced into the heating chamber 4 through the carburizing gas introduction pipe 15a from the upper gas inlet in the heating chamber 4. In addition, the gas can be introduced into the heating chamber 4 from the lower gas introduction port in the heating chamber 4 through the carburizing gas introduction pipe 15b.

  A third on-off valve 23a for opening and closing the carburizing gas introduction pipe 15a is provided in the carburizing gas introduction pipe 15a, and a fourth on-off valve 23b for opening and closing the carburizing gas introduction pipe 15b is provided. It is provided in the carburizing gas introduction pipe 15b.

  Furthermore, the control part 19 which sends a control signal to on-off valve 18a, 18b, 23a, 23b and controls opening / closing of these on-off valves 18a, 18b, 23a, 23b is provided. As shown in FIG. 9, for example, first, the control unit 19 uses the first on-off valve 18 a and the fourth on-off valve to introduce the carburizing gas into the heating chamber 4 from the lower gas inlet in the heating chamber. The valve 23b is opened, and the second on-off valve 18b and the third on-off valve 23a are closed. Thus, the carburizing gas introduced from the gas inlet at the lower portion of the heating chamber 4 is exhausted from the upper exhaust port in the heating chamber 4 by the vacuum pump 17, so that the carburizing gas is moved upward from below in the heating chamber. It flows toward. The on-off valves 18a and 18b and the control unit 19 constitute exhaust pipe selection means, and the on-off valves 23a and 23b and the control unit 19 constitute gas introduction pipe selection means. It should be noted that another appropriate unit that can switch the exhaust pipe may be used as the exhaust pipe selection means, and another appropriate one that switches the gas introduction pipe may be used as the gas introduction pipe selection means.

  Thereafter, as shown in FIG. 8, when a predetermined time has elapsed, the control unit 17 closes the first on-off valve 18a and the fourth on-off valve 23b, and the second on-off valve 18b and the third on-off valve 23a. Open. As a result, the carburizing gas introduced from the upper gas inlet of the heating chamber 4 is exhausted from the lower outlet of the heating chamber 4 by the vacuum pump 17. The gas flows from the top to the bottom. That is, the control unit 19 controls the opening and closing of the on-off valves 18a, 18b, 23a, and 23b as shown in FIG. 8, so that the direction of the flow of the carburizing gas introduced into the heating chamber 4 is alternately upward. And switch downwards. Thereby, carburizing of the material to be processed can be performed more uniformly by changing the position of the material to be processed 1 exposed to the flow of the carburizing gas. Note that carburizing gas may be continuously introduced from a gas inlet opening on the side of the heating chamber 4.

FIG. 9 shows a vacuum carburizing furnace 60 according to Reference Example 4 . Hereinafter, differences from the reference example 1 will be mainly described. According to the reference example 4 , one or a plurality of exhaust pipes 16 having exhaust ports that open to one side in the heating chamber 4 are provided, and further open into the heating chamber on the side facing the exhaust ports of these exhaust pipes 16. There are provided a gas introduction nozzle 12 having a gas introduction port and a gas introduction nozzle 12 having a gas introduction opening which opens to the upper and lower portions in the heating chamber 4 respectively.

  Further, a vacuum pump 17 is provided for sucking and exhausting the gas in the heating chamber 4 through the exhaust pipe 16 to decompress the heating chamber 4. In the heating chamber 4, a table 26 on which the workpiece 1 is placed is provided, and the table 26 is supported by a rotating shaft 27. In a state where the gas in the heating chamber is sucked and exhausted from the exhaust port by the vacuum pump 17, the carburizing gas is introduced into the heating chamber 4 from the gas introduction port of the gas introduction nozzle 12, and the workpiece 1 is carburized. However, at this time, when a predetermined time elapses, the table 26 is rotated through the rotary shaft 27 by the drive motor 28 by a predetermined angle. Thereby, the direction of the material 1 to be processed is changed. That is, by rotating the table 26 by a predetermined angle by the drive motor 28 every predetermined time, the direction of the workpiece 1 on the table 26 is changed every predetermined time. The rotation of the drive motor is controlled by a control unit (not shown). In this way, the table is stationary in a normal state, and the direction of the table is changed by the drive motor 28 every predetermined time. The table 26, the rotation shaft 27, the drive motor 28, and a control unit that controls the rotation of the drive motor (not shown) constitute a workpiece rotation means. In addition, you may use the other suitable thing which rotates a to-be-processed material as a to-be-processed material rotation means. Although the case where the table 26 is rotated intermittently has been described above, the table 26 may be rotated continuously.

  Thereby, the flow direction of the carburizing gas with respect to the material 1 changes every predetermined time. In the example of FIG. 9, the carburizing gas introduced from the gas introduction port of the gas introduction nozzle 12 located at the position facing the exhaust port in the heating chamber 4 passes through the workpiece to the opposite exhaust port. It flows toward. As a result, the position of the material to be processed facing the gas inlet located at the position facing the exhaust port is efficiently exposed to the flow of the carburizing gas. Other positions or portions of the workpiece are efficiently exposed to the carburizing gas flow when rotated by the drive motor 28. When the material to be treated is rotated and rotated once every predetermined time, the side surface portion of the material to be treated can be carburized using the carburizing gas efficiently.

  On the other hand, an appropriate amount of carburizing gas may be continuously introduced into the heating chamber 4 from the gas introduction ports of the upper and lower gas introduction nozzles 12 in the heating chamber 4. Thus, the to-be-processed material 1 can be carburized more uniformly by changing the position of the to-be-processed material 1 exposed to the flow of the carburizing gas.

FIG. 10 shows the vacuum carburizing furnace according to any one of the first embodiment, the second embodiment, and reference examples 1 to 4 , the cooling chamber 32 and the quenching oil tank 35 related thereto. In FIG. 10, the gas introduction nozzle 12, the exhaust pipe 16, and the like are omitted for simplicity. A front door 33 and an intermediate door 34 that can be opened and closed are attached to the cooling chamber 32. The workpiece 1 can be transferred to the cooling chamber 32 through the front door 33, and the workpiece 1 can be transferred from the cooling chamber 32 to the heating chamber 4 in the vacuum carburizing furnace through the intermediate door 34. Further, by lowering the elevator 36, the workpiece 1 can be immersed in the oil in the oil tank 35 to perform the quenching process. In addition, conveyance of the to-be-processed material 1 between the exterior, the cooling chamber 32, and the heating chamber 4 in a vacuum carburizing furnace is performed by the conveyance apparatus which is not shown in figure. Further, an exhaust pipe (not shown) for bringing the cooling chamber 32 into a vacuum state of a predetermined pressure and a vacuum pump (not shown) communicating with the cooling chamber 32 through the exhaust pipe are provided.

Next, the carburizing process using the vacuum carburizing furnace according to the first embodiment, the second embodiment, and the reference examples 1 to 4 having the above configuration will be described. First, the inside of the heating chamber 4 is heated from 930 ° C. to 1100 ° C. by the heater 8. The heating chamber 4 is set to a predetermined pressure (generally 1 Torr or less) by the vacuum pump 17. On the other hand, at this time, nitrogen gas is supplied to the cooling chamber 32 from, for example, a gas supply pipe (not shown), and the pressure in the cooling chamber 32 is set to atmospheric pressure.

  Next, the front door 33 is opened, the workpiece 1 is conveyed to the cooling chamber 32, and the front door 33 is closed. Thereafter, the pressure of the cooling chamber 32 is reduced to, for example, 1 Torr or less by a vacuum pump (not shown) by the vacuum pump, and the pressure in the cooling chamber 32 and the pressure in the heating chamber 4 are made the same.

  After making the inside of the heating chamber 4 and the cooling chamber 32 have the same pressure, the intermediate door 34 is opened, the workpiece 1 is conveyed into the heating chamber 4, and the intermediate door 34 is closed. When the intermediate door 34 is closed, it waits for the inside of the heating chamber 22 to return to the processing temperature (930 ° C. to 1100 ° C.). When the temperature is recovered, pretreatment is performed by holding the workpiece 1 in the heating chamber 4 for a predetermined time (generally, 40 minutes or more). At this time, the pressure in the cooling chamber 32 is restored to about 600 Torr.

  When the preheating is completed, the carburizing gas is introduced into the heating chamber 22 from the gas introduction port of the gas introduction nozzle 12. Thereby, the to-be-processed material 1 in a heating chamber is carburized by the carburizing gas introduced.

The flow of the carburizing gas in the heating chamber at this time will be described for each of the embodiments described above.
In the case of the vacuum carburizing furnaces 10 and 20 of the reference example 1 or the first embodiment , as shown in FIG. 1, the exhaust port used for sucking and exhausting the heating chamber is switched. In addition, the direction of the carburizing gas flow in the heating chamber changes. Thereby, the carburization of the to-be-processed material 1 is made more uniform by changing the position of the to-be-processed material 1 which is made to flow of the carburizing gas.

In the case of the vacuum carburizing furnace 30 of the reference example 2 , unlike the above, the carburizing gas is introduced only into the airtight container 22 in the heating chamber instead of being introduced into the heating chamber, and exhausted directly from the airtight container 22. Is done. Accordingly, it is possible to prevent the carburizing gas from leaking out of the airtight container 22 and to prevent deterioration of the insulation resistance of the electrode portion of the heater 8 provided outside the airtight container 22. Furthermore, since the exhaust port used for exhaust is switched, the direction of the flow of the carburizing gas in the airtight container 22 changes every time the exhaust port is switched. Therefore, the carburization of the material 1 can be performed more uniformly.

In the case of the vacuum carburizing furnace 40 of the second embodiment, the position for sucking and exhausting the heating chamber is fixed, but the position for introducing the carburizing gas into the heating chamber changes every time a predetermined time elapses. The flow of carburizing gas in the heating chamber 4 changes. Thereby, the carburization of the to-be-processed material 1 is made more uniform by changing the position of the to-be-processed material 1 which is made to flow of the carburizing gas.

In the case of the vacuum carburizing furnace 50 of the reference example 3 , the direction of the flow of the carburizing gas introduced into the heating chamber 4 is alternately changed upward and downward by switching the gas inlet and exhaust to be used as described above. Therefore, the position of the workpiece to be exposed to the carburizing gas is changed. Therefore, the material to be treated can be carburized more uniformly.

In the case of the vacuum carburizing furnace 60 of Reference Example 4 , the workpiece 1 placed on the table 26 in the heating chamber is rotated by a predetermined angle by the drive motor 28 via the rotary shaft 27 at predetermined intervals. . Thereby, every time the predetermined time elapses, the direction of the workpiece 1 changes. Therefore, since the material 1 to be treated changes its direction with respect to the flow of the carburizing gas in the heating chamber, the position of the material 1 to be treated exposed to the carburizing gas flow changes every predetermined time. Therefore, the carburizing of the workpiece 1 is performed more uniformly.

In this way, even after the carburizing gas is introduced into the heating chamber 4 for a predetermined time to carburize the workpiece 1, the supply of the carburizing gas is stopped and the heating chamber 4 is evacuated by the vacuum pump 17. Return to the degree of vacuum and perform diffusion treatment. When the diffusion process is completed, the material 1 is cooled to the quenching temperature and soaked. Thereafter, an inert gas of nitrogen gas is introduced into the heating chamber 4 and the furnace body 2 through an inert gas supply pipe (not shown), and after returning to, for example, 600 Torr, the inside of the heating chamber 4 and the cooling chamber 32 are connected to each other. Pressure. In the case of the reference example 2 , for example, the pressure in the airtight container is set to the same pressure in the heating chamber 4 and the cooling chamber 32 by operating the vacuum pump 17.

  Subsequently, the intermediate door 34 is opened, the workpiece 1 is moved from the heating chamber 4 to the cooling chamber 32 and conveyed onto the elevator 36, the intermediate door 34 is closed, the elevator 28 is lowered, and the oil in the oil tank 35 is covered. The treatment material 1 is immersed and a quenching process is performed. When the quenching process is completed, the elevator 28 is raised, the oil is cut off, the front door 33 is opened, and the workpiece 1 is unloaded from the cooling chamber 32. In this way, one cycle of vacuum carburization is performed.

  In addition, this invention is not limited to embodiment mentioned above, Of course, a various change can be added in the range which does not deviate from the summary of this invention.

It is a figure which shows the vacuum carburizing furnace by the reference example 1. FIG. It is a figure which shows switching of the on-off valve provided in the vacuum carburizing furnace of FIG. It is a figure which shows the vacuum carburizing furnace by 1st Embodiment of this invention. It is a figure which shows switching of the on-off valve provided in the vacuum carburizing furnace of FIG. It is a figure which shows the vacuum carburizing furnace by the reference example 2. FIG. It is a figure which shows the vacuum carburizing furnace by 2nd Embodiment of this invention. It is a figure which shows the vacuum carburizing furnace by the reference example 3. FIG. It is a figure which shows switching of the on-off valve provided in the vacuum carburizing furnace of FIG. It is a figure which shows the vacuum carburizing furnace by the reference example 4. FIG. It is a figure which shows the vacuum carburizing furnace in any one of 1st Embodiment, 2nd Embodiment, and Reference Examples 1-4 , and the cooling chamber and oil tank relevant to this.

Explanation of symbols

1 Material 1
2 Furnace 4 Heating chamber 6 Heat insulating material 8 Heater 10, 20, 30, 40, 50, 60 Vacuum carburizing furnace 12 Gas introduction nozzle 14 Carburizing gas supply sources 15a, 15b, 15c, 15d Carburizing gas introduction pipes 16a, 16b , 16c, 16d Exhaust pipe 17 Vacuum pumps 18a, 18b, 18c, 18d Open / close valve 19 Control unit 22 Airtight containers 23a, 23b, 23c, 23d Open / close valve 26 Table 27 Rotating shaft 28 Drive motor 32 Cooling chamber 33 Front door 34 Intermediate Door 35 Oil tank 36 Elevator

Claims (8)

A hollow heating chamber that accommodates a material to be vacuum carburized therein, a heater that is located in the heating chamber and that heats the material to be processed, a gas introduction pipe for carburization that introduces a carburizing gas into the heating chamber, and a heating chamber A vacuum pump for sucking and exhausting the gas, first, second, third and fourth gas exhaust pipes communicating with the vacuum pump and the heating chamber, and the first, second, third and second An exhaust pipe selecting means for sequentially opening four gas exhaust pipes one by one ,
Each of the gas exhaust pipes has an exhaust port that opens into the heating chamber,
The exhaust port of the first gas exhaust pipe is located on one side in the first direction, the exhaust port of the second gas exhaust pipe is located on the other side in the first direction, and between these one side and the other side The treated material is located,
The exhaust port of the third gas exhaust pipe is located on one side in the second direction orthogonal to the first direction, and the exhaust port of the fourth gas exhaust pipe is located on the other side in the second direction. A vacuum carburizing furnace , wherein the material to be treated is located between the other side . The exhaust pipe selection means closes all other gas exhaust pipes while one of the first, second, third and fourth gas exhaust pipes is open. The vacuum carburizing furnace according to claim 1, wherein: A hollow heating chamber for accommodating a material to be vacuum carburized therein, a heater for heating the material to be processed located in the heating chamber, a first, a second, a third and a third for introducing a carburizing gas into the heating chamber A fourth carburizing gas introduction pipe, a vacuum pump for sucking and exhausting the gas in the heating chamber, a gas exhaust pipe communicating the vacuum pump and the heating chamber, and first, second, third and fourth Gas introduction pipe selection means for sequentially opening the gas introduction pipes one by one,
Each of the gas introduction pipes has a gas introduction opening that opens into the heating chamber, and the gas exhaust pipe has an exhaust opening that opens into the heating chamber;
The gas introduction port of the first gas introduction pipe is located on one side in the first direction, and the gas introduction port of the second gas introduction pipe is located on the other side in the first direction. The material to be processed is located between
The gas introduction port of the third gas introduction pipe is located on one side in the second direction orthogonal to the first direction, and the gas introduction port of the fourth gas introduction pipe is located on the other side in the second direction. A vacuum carburizing furnace, wherein the material to be treated is located between the side and the other side. The gas introduction pipe selection means closes all the other gas introduction pipes while one of the first, second, third and fourth gas introduction pipes is open. The vacuum carburizing furnace according to claim 3, wherein A hollow heating chamber that accommodates a material to be vacuum carburized therein, a heater that is located in the heating chamber and that heats the material to be processed, a gas introduction pipe for carburization that introduces a carburizing gas into the heating chamber, and a heating chamber A vacuum pump for sucking and exhausting the gas, and first, second, third, and fourth gas exhaust pipes that communicate the vacuum pump and the heating chamber,
Each of the gas exhaust pipes has an exhaust port that opens into the heating chamber,
The exhaust port of the first gas exhaust pipe is located on one side in the first direction, the exhaust port of the second gas exhaust pipe is located on the other side in the first direction, and between these one side and the other side The treated material is located,
The exhaust port of the third gas exhaust pipe is located on one side in the second direction orthogonal to the first direction, and the exhaust port of the fourth gas exhaust pipe is located on the other side in the second direction. The material to be processed is located between the other side,
In order to carburize the material to be processed placed in the heating chamber under reduced pressure, a carburizing gas is introduced into the heating chamber, and the first, second, third and fourth gas exhaust pipes are sequentially placed one by one. A vacuum carburizing method characterized by opening. 6. All the other gas exhaust pipes are closed while any one of the first, second, third and fourth gas exhaust pipes is open. The vacuum carburizing method described in 1. A hollow heating chamber for accommodating a material to be vacuum carburized therein, a heater for heating the material to be processed located in the heating chamber, a first, a second, a third and a third for introducing a carburizing gas into the heating chamber A fourth carburizing gas introduction pipe, a vacuum pump for sucking and exhausting the gas in the heating chamber, and a gas exhaust pipe communicating the vacuum pump and the heating chamber;
Each of the gas introduction pipes has a gas introduction opening that opens into the heating chamber, and the gas exhaust pipe has an exhaust opening that opens into the heating chamber;
The gas introduction port of the first gas introduction pipe is located on one side in the first direction, and the gas introduction port of the second gas introduction pipe is located on the other side in the first direction. The material to be processed is located between
The gas introduction port of the third gas introduction pipe is located on one side in the second direction orthogonal to the first direction, and the gas introduction port of the fourth gas introduction pipe is located on the other side in the second direction. The material to be treated is located between the side and the other side,
In order to carburize the material to be processed placed in the heating chamber under reduced pressure, the first, second, third and fourth carburizing gas introduction pipes are opened one by one in order, and the carburizing gas is supplied to the heating chamber. A vacuum carburizing method comprising introducing and exhausting the carburizing gas from a gas exhaust pipe. 8. All of the other gas introduction pipes are closed while any one of the first, second, third, and fourth gas introduction pipes is open. The vacuum carburizing method described in 1.

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