JP5647776B2 - Gas carburizing equipment - Google Patents

Description

  The present invention relates to a gas carburizing apparatus configured to perform a carburizing process on a workpiece using a hydrocarbon gas.

  When carburizing alloy steel or the like with a hydrocarbon gas such as methane, the hydrocarbon gas is decomposed to generate hydrogen gas. Therefore, during the carburizing process, in order to manage the carburizing gas concentration in the processing chamber and grasp the carburizing depth of the product to be processed, sufficient ventilation is provided to discard the hydrogen gas generated during carburizing, It was necessary to accurately detect the hydrogen gas concentration in the processing chamber.

  Conventionally, in order to manage carburizing gas concentration conditions with higher accuracy and obtain a desired carburizing depth, it is preferable to perform high-speed and high-precision carburizing gas flow rate control or to measure the gas concentration in the processing chamber. It was said.

  For example, in the prior art, a hydrogen partial pressure ratio detecting means for detecting a hydrogen partial pressure ratio with respect to the total pressure in the processing chamber at the time of the carburizing process is provided, and the carbon inflow rate to the workpiece is determined based on the temporal change of the hydrogen partial pressure ratio (For example, refer to Patent Document 1). And it was supposed that the estimated value of the carburization depth of a to-be-processed product can be obtained by employ | adopting such a technique.

JP 2007-113046 A

  In the technique according to the above-mentioned Patent Document 1, it is necessary to provide a sensor for detecting the concentration of hydrogen gas in the processing chamber in order to grasp the carburized state of the product to be processed. There was a tendency to become.

  Moreover, in the prior art including the technique according to Patent Document 1 described above, when the gas in the processing chamber is exhausted, the undecomposed carburized gas is also discarded at the same time, so that a large amount of gas must be discarded. And since heat dissipation from the processing chamber occurs as the gas is discarded, a lot of heat energy has been wasted.

  The object of the present invention is to grasp the carburized state of a workpiece without providing a sensor for detecting the concentration of hydrogen gas in the processing chamber, and to minimize the amount of gas discarded. Is to provide a gas carburizing apparatus.

  The gas carburizing apparatus according to the present invention is configured to perform a carburizing process on a workpiece using a hydrocarbon gas. This gas carburizing apparatus includes a processing chamber, a heating means, a gas introduction part, a gas discharge part, a hydrogen separation unit, and a gas feedback part.

  The processing chamber is configured to accommodate a workpiece to be carburized. The heating means is configured to heat the workpiece in the processing chamber. A representative example of the heating means includes a high frequency induction heating coil, but is not limited thereto. For example, it is possible to use various heaters such as those that perform light heating using infrared rays or ultraviolet rays, and those that perform laser heating using laser light.

The carburizing gas introduction unit is configured to introduce at least a carburizing hydrocarbon gas into the processing chamber . Preferably methane gas as a hydrocarbon gas for carburizing, but it is also possible to use a hydrocarbon gas other than methane. The carburizing gas introduction unit includes a relief valve that introduces the hydrocarbon gas into the processing chamber so that the pressure inside the processing chamber is constant. The gas discharge unit is configured to discharge the gas in the processing chamber.

  The hydrogen separation unit is provided in the gas discharge unit and configured to collect and separate only hydrogen gas from the gas discharged from the processing chamber. Examples of the configuration of the hydrogen separation unit include those provided with a hydrogen separation membrane, but the configuration of the usable hydrogen separation membrane is not particularly limited, and a known hydrogen separation membrane can be appropriately used. The gas feedback unit is configured to return a gas other than hydrogen gas out of the gas guided to the hydrogen separation unit to the processing chamber.

  In this configuration, it is not necessary to discard undecomposed hydrocarbon gas, dilution gas, etc., and it becomes possible to selectively discard or collect only hydrogen gas generated during carburizing treatment. It becomes possible to reduce.

  In addition, by disposing only hydrogen gas, the concentration of carburizing hydrocarbon gas in the processing chamber can be easily maintained at a constant level. It becomes possible to grasp the speed and the like.

  In addition to the above-described configuration, a pressure increasing mechanism disposed upstream of the hydrogen separation unit in the discharge path configured by the gas discharge unit, and a pressure holding mechanism disposed in the feedback path configured by the gas feedback unit, Is preferably provided. This is because more hydrogen gas can be separated by applying pressure to the hydrogen separation unit.

  According to the present invention, it is possible to grasp the carburized state of a workpiece without providing a sensor for detecting the concentration of hydrogen gas in the processing chamber, and it is possible to minimize the amount of gas discarded. It is.

It is a figure showing the outline of the gas carburizing processing device concerning a 1st embodiment of the present invention. It is a figure which shows the outline of the gas carburizing processing apparatus which concerns on the 2nd Embodiment of this invention.

  A gas carburizing apparatus 10 according to an embodiment of the present invention will be described with reference to FIG. The gas carburizing apparatus 10 includes a processing chamber 20 configured to accommodate a workpiece 22 such as alloy steel to be carburized. The gas carburizing apparatus 10 further controls the carburizing gas supply unit 242, the dilution gas supply unit 244, the gas introduction unit 12, the high frequency induction heating coil 18, the gas discharge unit 14, the gas feedback unit 16, and the operation thereof. The control part 30 which controls automatically is provided.

  The carburizing gas supply unit 242 is configured to selectively output a carburizing hydrocarbon gas (for example, methane gas) to be supplied to the processing chamber 20 based on the control content from the control unit 30. The dilution gas supply unit 244 is configured to selectively output a dilution gas (for example, nitrogen gas) based on the control content from the control unit 30. In this embodiment, methane gas is used as the carburizing hydrocarbon gas and nitrogen gas is used as the dilution gas. However, the type of gas used is not limited thereto.

The gas introduction unit 12 is configured to connect the gas introduction pipe 127 configured to connect the carburizing gas supply unit 242 and the processing chamber 20, and the dilution gas supply unit 244 and the processing chamber 20. A gas introduction pipe 128 is provided. The gas introduction pipe 127 is provided with an on / off switching valve 121, a flow rate adjustment valve valve 123, and a relief valve 125. On the other hand, the gas introduction pipe 128 is provided with an on / off switching valve 122, a flow rate adjustment valve valve 124, and a relief valve 126. The operations of the on / off switching valves 121 and 122 and the flow rate adjusting valve valves 123 and 124 are controlled based on the control content of the control unit 30. However, these valves can be configured to be manually operated. The gas introduction part 12 includes the carburizing gas introduction part and the dilution gas introduction part of the present invention.

  The high frequency induction heating coil 18 is disposed inside the processing chamber 20 and is configured to induction heat the workpiece 22 based on the control content of the control unit 30. However, the arrangement position of the high frequency induction heating coil 18 is not limited to this, and for example, the high frequency induction heating coil 18 may be arranged outside the processing chamber 20.

  The gas discharge unit 14 is configured to discharge gas from the processing chamber 20, and includes a first exhaust duct 145, a hydrogen separation unit 142, a second exhaust duct 147, and a first pump 144. . The first exhaust duct 145 is connected to the processing chamber 20. The hydrogen separation unit 142 includes a hydrogen separation membrane, and collects and separates only hydrogen gas from a mixed gas containing hydrogen gas and hydrocarbon gas discharged from the processing chamber 20 via the first exhaust duct 145. Configured to do. The second exhaust duct 147 is connected to the hydrogen separation unit 142 and is configured to discharge the hydrogen gas collected by the hydrogen separation unit 142. The first pump 144 is configured to generate a suction force for sucking the hydrogen gas collected by the hydrogen separation unit 142 into the second exhaust duct 147.

  The gas feedback section 16 includes a feedback duct 165 connected to connect the hydrogen separation unit 142 and the processing chamber 20, and a gas other than hydrogen (mainly carbonized) in the mixed gas guided to the hydrogen separation unit 142. (Hydrogen gas) is returned to the processing chamber 20 again.

  Then, the carburizing method with respect to the workpiece | work 22 in the gas carburizing apparatus 10 is demonstrated easily. During the carburizing process, first, the work 22 is placed on a work support (not shown) in the processing chamber 20. At this time, the inside of the processing chamber 20 is substantially equal to the atmospheric pressure. Thereafter, the control unit 30 supplies methane gas and, if necessary, nitrogen gas from the carburizing gas supply unit 242 and the dilution gas supply unit 244 to the processing chamber 20. The on / off switching valve 122 between the dilution gas supply unit 244 and the processing chamber 20 is closed during the carburizing process. For this reason, nitrogen gas is exclusively recycled for carburizing.

  After the carburizing atmosphere is formed in the processing chamber 20, the work 22 is induction heated by the high frequency induction heating coil 18. In this embodiment, the high frequency induction heating coil 18 is controlled to heat the workpiece 22 to about 1200 ° C., but the example of the heating temperature is not limited to this.

  During the carburizing process, methane gas in the processing chamber 20 is decomposed to generate hydrogen gas. For this reason, the control unit 30 generates a negative pressure in the first exhaust duct 145 by the first pump 144 during the carburizing process, and the mixed gas containing hydrogen gas and methane gas in the processing chamber 20 is the first. The air is sucked into the exhaust duct 145. The mixed gas containing hydrogen gas and methane gas introduced into the first exhaust duct 145 is separated by the hydrogen separation unit 142. Then, hydrogen gas contained in the mixed gas is discharged through the second exhaust duct 147, and other gases are returned into the processing chamber 20 through the return duct 165.

  At this time, if only the hydrogen gas generated at the time of carburizing is recovered and the same amount of hydrocarbon gas as the recovered hydrogen gas is supplied, the pressure in the processing chamber 20 is kept constant. It becomes possible to keep the hydrocarbon gas concentration constant. In the case of methane gas, about half of the amount of hydrogen gas discarded or recovered is replenished. Here, when the pressure in the processing chamber 20 decreases due to the recovery of the hydrogen gas, the relief valve 125 is opened, and a mechanism in which the hydrocarbon gas corresponding to the negative pressure is replenished is adopted. By using such a mechanism, a gas concentration measuring device, a carburizing hydrocarbon gas flow rate controller, and the like become unnecessary, and the production cost of the gas carburizing apparatus 10 can be reduced.

  After the carburizing process, the process proceeds to the diffusion process. At that time, the on / off switching valve 121 between the carburizing gas supply unit 242 and the processing chamber 20 is closed, while the on / off switching valve 122 between the dilution gas supply unit 244 and the processing chamber 20 is opened. Therefore, nitrogen gas is appropriately replenished in the processing chamber 20 even when shifting to the diffusion processing.

  Then, the gas carburizing apparatus 11 which concerns on 2nd Embodiment is demonstrated using FIG. Since the basic structure of the gas carburizing apparatus 11 is the same as that of the gas carburizing apparatus 10 described above, the description thereof is omitted. In the gas carburizing apparatus 11, in addition to the gas carburizing apparatus 10 described above, a second pump 146 and a relief valve 162 are further provided.

  The second pump 146 is disposed upstream of the hydrogen separation unit 142 and functions as a pressure increasing mechanism, while the relief valve 162 is disposed downstream of the hydrogen separation unit 142 and functions as a pressure holding mechanism. Thus, by arranging the second pump 146 and the relief valve 162 so as to sandwich the hydrogen separation unit 142, the pressure applied to the hydrogen separation unit 142 can be increased by operating the second pump 146. It becomes possible. Since the hydrogen separation membrane of the hydrogen separation unit 142 generally has a larger amount of hydrogen separated due to an increase in applied pressure, more hydrogen gas can be separated by the hydrogen separation unit 142. Become. As a result, even when the hydrogen separation unit 142 is downsized, it is possible to appropriately separate the hydrogen gas. Usually, since a high-precision hydrogen separation membrane is expensive, the production cost of the hydrogen separation unit 142 is reduced by downsizing the hydrogen separation unit 142.

  According to the above embodiment, since the amount of gas discarded from the processing chamber 20 can be reduced, gas saving can be achieved. Along with this, the amount of heat released from the processing chamber 20 can be reduced, so that energy saving can be realized.

  Further, by discarding only the hydrogen gas, the concentration of the carburizing hydrocarbon gas in the processing chamber 20 can be easily maintained constant, so that the work 22 can be performed without providing a hydrogen gas concentration sensor or the like. It is possible to grasp the carbon inflow rate of the steel and the carburized state of the workpiece 22.

  The above description of the embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

DESCRIPTION OF SYMBOLS 10-Gas carburizing processing apparatus 12-Gas introduction part 14-Gas discharge part 16-Gas feedback part 18-High frequency induction heating coil 20-Processing chamber 22-Work 30-Control part 242-Carburizing gas supply part 244-For dilution Gas supply unit

Claims (3)

A gas carburizing apparatus configured to perform a carburizing process on a workpiece using a hydrocarbon gas,
A processing chamber configured to accommodate a workpiece to be carburized;
Heating means for heating the workpiece in the processing chamber;
And carburizing gas inlet configured to introduce a hydrocarbon gas for coal immersion in respect to the processing chamber,
A gas discharge unit configured to discharge the gas in the processing chamber;
A hydrogen separation unit provided in the gas discharge unit, configured to collect and separate hydrogen gas from the gas discharged from the processing chamber;
A gas feedback unit configured to be separated from the gas introduction unit so that a gas other than hydrogen gas among the gases guided to the hydrogen separation unit is returned to the processing chamber;
With
The gas carburizing apparatus, wherein the carburizing gas introduction unit includes a relief valve that introduces the hydrocarbon gas into the processing chamber so that the pressure inside the processing chamber is constant . Further comprising a dilution gas introduction part for supplying a dilution gas to the processing chamber;
The dilution gas introduction unit includes a relief valve that introduces the dilution gas into the processing chamber so that the pressure inside the processing chamber is constant,
  2. The gas carburizing apparatus according to claim 1, wherein the carburizing gas introducing unit and the dilution gas introducing unit are selectively enabled during carburizing treatment and diffusion treatment, respectively. A pressure increasing mechanism disposed upstream of the hydrogen separation unit in a discharge path constituted by the gas discharge unit;
The gas carburizing treatment apparatus according to claim 1 or 2 and the holding pressure mechanism disposed in the feedback path formed, further comprising a by gas recirculation unit.

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