JP2017106062A - Surface treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treatment apparatus capable of suitably implementing a surface treatment of an inner surface and an outer surface each even if a surface treatment condition for a surface facing an internal space of an object to be treated differs from that for an outer surface of the object to be treated.SOLUTION: A surface treatment apparatus 1 includes a treatment furnace 2 housing an object to be treated, a gas supply port 3 supplying gas to the treatment furnace 2, and a gas exhaust port 4 exhausting gas from the treatment furnace 2. The surface treatment apparatus 1 includes a gas pipeline 5 inserted into an internal space WI of an object to be treated W, and a gas pipeline control part 6 which switches gas supply to the gas pipeline 5 and gas exhaustion from the gas pipeline 5, not depending from gas supply to the gas supply port 3 and gas exhaustion from the gas exhaust port 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a surface treatment apparatus.

  2. Description of the Related Art Conventionally, there has been known an invention for carrying out surface hardening treatment of a component deep hole in a vacuum furnace with respect to the surface hardening treatment of the component deep hole (see Patent Document 1 below). The surface hardening treatment method for the deep hole of a part described in Patent Document 1 is a metal surface treatment apparatus for controlling the atmosphere in a furnace such as a vacuum furnace, and a part to be surface-treated in a furnace maintained at a predetermined temperature. Deploy.

  Then, the processing gas is supplied to the deep holes of the parts to be surface-treated, and the furnace atmosphere is exhausted so as to maintain a predetermined pressure, thereby causing forced convection of the processing gas supplied into the deep holes. The contact between the processing gas and the inner wall of the hole is maintained under the required conditions. Thereby, the decomposition of gas and the permeation diffusion process are uniformly performed on the deep hole back part. More specifically, the permeation diffusion process is performed on the deep hole depth by the following procedure.

  First, parts, gas transport pipes, and fixtures are washed and dried, then placed in a heating space in a vacuum furnace and placed in a suitable place. Further, after the pressure in the heating space of the vacuum furnace is reduced, the heating space is heated to the processing temperature. The processing gas is continuously sent to the deep hole through the transport pipe at a pressure slightly higher than the pressure in the heating space and at an appropriate flow rate. The vacuum space is maintained at a set low pressure state by a vacuum pump, and the processing gas is inevitably forced out of the inner hole wall and out of the hole, and simultaneously decomposes, permeates and diffuses toward the hole wall.

JP 2003-27209 A

  The surface treatment conditions may differ between the inner surface facing the internal space of the object to be processed, such as a deep hole of a part, and the outer surface of the object to be processed. However, in the surface hardening processing method described in Patent Document 1, the processing gas supplied from the transport pipe to the deep hole of the component and the processing gas supplied from the gas supply port to the outer surface of the component are heated space. It is discharged from one gas outlet provided in the. Therefore, it is difficult to appropriately perform the surface treatment of the deep hole of the component to be surface-treated and the surface treatment of the outer surface under different conditions.

  The present invention has been made in view of the above problems, and even if the inner surface facing the inner space of the object to be processed, such as a deep hole, and the outer surface of the object to be processed have different surface treatment conditions, the inner surface An object of the present invention is to provide a surface treatment apparatus capable of appropriately performing surface treatment on the outer surface and the outer surface.

  In order to achieve the above object, a surface treatment apparatus according to the present invention includes a treatment furnace that accommodates an object to be treated, a gas supply port that supplies gas to the treatment furnace, and a gas discharge port that discharges gas from the treatment furnace. A gas pipe inserted into the internal space of the object to be processed, gas supply to the gas supply port, and gas discharge from the gas discharge port independently of the gas And a gas pipeline control unit that switches between supply of gas to the pipeline and discharge of gas from the gas pipeline.

The surface treatment apparatus of the present invention, for example, accommodates an object to be processed such as a metal part or a mold in a processing furnace, and gas such as N ₂ , NH ₃ , CO ₂ , or H _{2 with} respect to the surface of the object to be processed. Is a device for performing surface treatment such as nitriding.

  For example, forging molds need to produce good products in large quantities in a short time, so cooling water is introduced from the surface opposite to the cavity for forging the forged product to the vicinity of the surface forming the cavity. Cooling holes may be provided. The mold cooling hole is likely to crack due to corrosion by cooling water and repeated stress accompanying the temperature rise and cooling of the mold. If a crack occurs in the cooling hole, water leaks from the crack, which contributes to shortening the life of the mold.

  Therefore, for the purpose of extending the life of the mold, the surface of the mold is subjected to surface treatment such as nitriding, but the inner surface facing the cooling hole of the mold and the outer surface of the mold forming the cavity are: Different surface treatments may be required. Specifically, it may be necessary to perform a surface treatment with high durability against heat cracks on the outer surface of the mold and to perform a surface treatment with high durability against stress corrosion cracking on the inner surface of the die.

  Here, the surface treatment apparatus of the present invention supplies the gas necessary for the surface treatment from the gas supply port to the outer surface of the workpiece accommodated in the processing furnace, such as the outer surface of the mold, and the gas discharge port. Thus, unnecessary gas in the processing furnace can be discharged. Thereby, the surface treatment suitable for the outer surface of the workpiece can be performed independently of the surface treatment of the inner surface of the workpiece.

  Further, a gas pipe line is inserted into the inner space of the object to be processed, such as a cooling hole of a mold, and the gas pipe line controller controls the inner surface of the object to be processed from the gas pipe line independently of the gas supply port. A gas necessary for the surface treatment can be appropriately supplied. In addition, the gas pipe control unit can switch between gas supply and discharge, and can appropriately discharge unnecessary gas in the internal space of the object to be processed from the gas pipe independently of the gas discharge port. Thereby, the surface treatment suitable for the inner surface of the workpiece can be performed independently of the surface treatment of the outer surface of the workpiece.

  As can be understood from the above description, according to the present invention, even when the conditions of the surface treatment between the inner surface facing the inner space of the workpiece and the outer surface of the workpiece are different, the inner surface and the outer surface A surface treatment apparatus capable of appropriately performing surface treatment can be provided.

The schematic block diagram of the surface treatment apparatus which concerns on embodiment of this invention. The perspective view which shows the gas supply path | route and gas discharge path | route of the surface treatment apparatus shown in FIG. FIG. 2 is a perspective view of a gas pipe line support portion shown in FIG. 1. The graph which shows the relationship between the gas flow rate from a gas supply port, furnace temperature, and time. The graph which shows the relationship between the gas flow rate from a gas pipe line, the furnace temperature, and time. The graph which shows the relationship between the depth from the outer surface of a to-be-processed object, and hardness. The graph which shows the relationship between the depth from the inner surface of a to-be-processed object, and hardness. The graph which shows the relationship between the temperature of a to-be-processed object, and elapsed time. The schematic diagram of the apparatus for performing the durability test of the inner surface of a to-be-processed object. An enlarged cross-sectional photograph of the vicinity of the outer surface of the workpiece. An enlarged cross-sectional photograph of the vicinity of the inner surface of the workpiece.

  Hereinafter, embodiments of the surface treatment apparatus of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a surface treatment apparatus 1 according to an embodiment of the present invention. FIG. 2 is a perspective view showing a gas supply path and a gas discharge path of the surface treatment apparatus 1 shown in FIG. FIG. 3 is a perspective view of the gas pipe line support portion 7 shown in FIG.

The surface treatment apparatus 1 of the present embodiment includes a processing furnace 2 that accommodates the workpiece W, a gas supply port 3 that supplies gas to the processing furnace 2, and a gas discharge port 4 that discharges gas from the processing furnace 2. The gas pipe 5 is inserted into the internal space WI of the workpiece W. The surface treatment apparatus 1 according to the present embodiment accommodates an object to be processed W such as a metal part or a mold D in a processing furnace 2, and N ₂ , NH ₃ , CO _{2 with} respect to the surface of the object to be processed W. , An apparatus for supplying a gas such as H ₂ and performing surface treatment such as nitriding.

  Although details will be described later, the surface treatment apparatus 1 according to the present embodiment supplies gas to the gas pipeline 5 independently of gas supply to the gas supply port 3 and gas discharge from the gas discharge port 4. And a gas pipe line control unit 6 that switches between gas discharge from the gas pipe line 5. Hereinafter, each structure of the surface treatment apparatus 1 of this embodiment is demonstrated in detail.

The processing furnace 2 includes a support part 21 that supports a workpiece W such as a metal part or a mold D accommodated therein, a gas sensor 22 provided on a ceiling part, and a wall surface provided with a gas supply port 3. And a convection fan 23 provided on the opposite wall surface. The gas sensor 22 measures the flow rate of the gas supplied into the processing furnace 2 such as N ₂ , NH ₃ , CO ₂ , H _{2, and the} like. The convection fan 23 convects the gas supplied into the processing furnace 2 inside the processing furnace 2.

  The gas supply port 3 opens to the wall surface of the processing furnace 2, and the gas for external surface treatment is supplied to the gas supply system for external surface treatment that supplies gas for performing the surface treatment of the external surface OF of the workpiece W. They are connected via a supply pipe 31. The gas discharge port 4 opens to the wall surface of the processing furnace 2 and is connected to a gas processing system that collects and processes the gas discharged from the processing furnace 2 through an exhaust pipe 41. The exhaust pipe 41 is provided with an exhaust valve 42 that exhausts gas at a predetermined pressure.

  The gas pipe line control unit 6 is provided in, for example, a switching valve 61 connected to one end of the gas pipe line 5, an internal gas discharge pipe 62 connecting the switch valve 61 and the exhaust pipe 41, and the internal gas discharge pipe 62. The suction machine 63 is provided. The switching valve 61 has an inner surface treatment gas supply pipe 64 for an inner surface treatment gas supply system for supplying a gas for performing a surface treatment of the inner surface IF facing the inner space WI of the workpiece W. Connected through. The suction machine 63 is driven by a predetermined control signal, sucks the gas in the internal gas discharge pipe 62 and sends it to the exhaust pipe 41.

  In the switching valve 61, for example, a valve body 61a is driven by a motor or the like, and the flow of gas is switched by a predetermined control signal. The valve body 61a of the switching valve 61 has, for example, a T-shaped flow path, and connects the gas supply pipe 64 and the gas pipe line 5 by rotation of 90 °, and the gas pipe line 5 and the internal gas discharge pipe 62. A state in which the gas flow between the gas pipe 5 and the internal gas discharge pipe 62 is connected, and a gas flow between the gas supply pipe 64 and the gas pipe 5 is cut off. Switch.

  As shown in FIG. 3, the gas pipeline 5 is constituted by, for example, a flexible hose 5a having flexibility and a metal straight pipe 5b connected to the tip of the flexible hose 5a via a joint 5c. . The flexible hose 5a is branched into a plurality at the base end connected to the switching valve 61, and the plurality of distal ends of the flexible hose 5a are connected to the plurality of straight pipes 5b. The straight pipe 5 b is supported by the gas pipe line support portion 7 and is inserted into the internal space WI of the workpiece W.

  In the surface treatment apparatus 1 of this embodiment, the forging die D is illustrated as the workpiece W accommodated in the processing furnace 2, but various metal parts, tools, and the like are also treated. Surface treatment can be performed as the object W. In the illustrated example, the mold D is provided from a concave outer surface OF that forms a cavity for forging a forged product and from the outer surface OF on the opposite side of the cavity to the vicinity of the outer surface OF that forms the cavity. It has a plurality of cooling holes CC.

  The cooling hole CC is a deep hole for cooling the mold D by introducing cooling water in order to forge a large quantity of good products in a short time with the mold D. An internal space WI is formed. That is, in the surface treatment apparatus 1 of the present embodiment, the inner surface IF facing the inner space WI of the workpiece W is the surface of the cooling hole CC of the mold D, and the outer surface OF of the workpiece W is It is the outer surface OF of the mold D that forms the cavity of the mold D.

  The gas pipe line support portion 7 supports the straight pipe 5 b at the tip of the gas pipe line 5 inserted into the cooling hole CC of the mold D in the processing furnace 2. The gas pipe line support unit 7 includes a mounting table 71 on which the straight pipe 5b at the tip of the gas pipe line 5 is mounted, a rail unit 72 that supports the mounting table 71 so as to be movable up and down, and a gas pipe line on the mounting table 71. 5 and a clamp portion 73 for fixing the straight pipe 5b at the tip of the tip 5.

  Hereinafter, the operation of the surface treatment apparatus 1 of the present embodiment will be described.

  For example, in order to perform surface treatment of the mold D as the workpiece W of the surface treatment apparatus 1, first, the mold D is accommodated in the processing furnace 2 and supported by the support portion 21. Next, the straight pipe 5 b at the tip of the gas pipe 5 is inserted into the cooling hole CC of the mold D and supported by the gas pipe support 7.

  For example, first, the mounting table 71 on which the straight pipe 5b is mounted is moved up and down along the rail portion 72, the vertical pipe 5b and the cooling hole CC are aligned in the vertical direction, and the mounting table 71 is moved to the rail portion 72. Secure to. Next, the straight pipe 5b at the tip of the gas pipe 5 placed on the placing table 71 and the cooling hole CC of the mold D are aligned in the horizontal direction, and the straight pipe 5b is inserted into the cooling hole CC. The straight pipe 5 b is fixed to the mounting table 71 by the clamp portion 73. Next, gas is supplied from the gas supply system for external surface treatment into the processing furnace 2 through the gas supply pipe 31 and the gas supply port 3, and the processing furnace is connected through the gas discharge port 4 and the exhaust pipe 41. The gas in 2 is discharged.

  Further, the switching valve 61 of the gas pipe line control unit 6 is switched to connect the gas supply pipe 64 and the gas pipe line 5 so that the gas flow between the gas pipe line 5 and the internal gas discharge pipe 62 is cut off. To. Then, gas is supplied from the gas supply system for inner surface treatment into the cooling hole CC of the mold D through the gas supply pipe 64, the switching valve 61, and the gas pipe line 5. Alternatively, the switching valve 61 of the gas pipe line control unit 6 is switched to connect the gas pipe line 5 and the internal gas discharge pipe 62 to block the gas flow between the gas supply pipe 64 and the gas pipe line 5. Put it in a state. Then, the suction machine 63 is driven, and the gas inside the cooling hole CC of the mold D is discharged to the exhaust pipe 41 through the gas pipe 5, the switching valve 61, and the internal gas discharge pipe 62.

  FIG. 4 is a graph showing the relationship between the flow rate of the gas supplied into the processing furnace 2 via the gas supply port 3, the temperature in the processing furnace 2, and time. FIG. 5 is a graph showing the relationship between the flow rate of the gas supplied to the cooling hole CC of the mold D through the gas pipe 5 and the temperature and time in the processing furnace 2.

The surface treatment apparatus 1 first performs a pretreatment for discharging the atmosphere remaining in the processing furnace 2 and the cooling hole CC of the mold D. Specifically, after the start of the surface treatment, the temperature in the processing furnace 2 is raised to about 580 ° C. and maintained at about 580 ° C. for about 45 minutes. In the meantime, N ₂ gas is supplied into the processing furnace 2 through the gas supply port 3 at a flow rate of about 25 L per minute, and the gas in the processing furnace 2 is discharged through the gas discharge port 4. At the same time, N ₂ gas is supplied into the cooling hole CC of the mold D through the gas pipe 5 at a flow rate of about 25 L / min, or the cooling hole CC of the mold D is supplied through the gas pipe 5. The gas inside is exhausted.

Next, the temperature in the processing furnace 2 is maintained at about 560 ° C. for about 300 minutes. Meanwhile, a gas for processing the outer surface OF of the mold D is supplied into the processing furnace 2 through the gas supply port 3. For example, NH ₃ gas is supplied at a flow rate of about 20 L / min, H ₂ gas is supplied at a flow rate of 5 L to 10 L / min, N ₂ gas is supplied at a flow rate of ₂ L to 3 L / min, and CO 2 is supplied. _Two gases are supplied at a flow rate of 1 L or less per minute. Further, the gas in the processing furnace 2 is discharged at a predetermined flow rate through the gas discharge port 4.

At the same time, a gas for processing the inner surface IF of the mold D is supplied into the cooling hole CC of the mold D through the gas pipe 5. For example, NH ₃ gas is supplied at a flow rate of approximately 20 L / min, H ₂ gas is supplied at a flow rate of approximately 7 L / min, N ₂ gas is supplied at a flow rate of approximately ₂ L / min, and CO ₂ gas is supplied per minute. Supply at a flow rate of 1 L or less.

The gas for processing the inner surface IF of the mold D supplied to the inside of the cooling hole CC of the mold D via the gas pipe 5 is stopped after about 180 minutes from the start of supply. Thereafter, the switching valve 61 of the gas pipeline control unit 6 is switched and the suction machine 63 is driven to discharge the gas inside the cooling hole CC of the mold D via the gas pipeline 5. On the other hand, the gas for processing the outer surface OF of the mold D supplied into the processing furnace 2 through the gas supply port 3 is continuously supplied for about 300 minutes from the start of supply. Thereafter, the supply of N ₂ gas from the gas supply port 3 is increased to about 50 L per minute, the supply of gases other than N ₂ is stopped, and the temperature in the processing furnace 2 is lowered.

  FIG. 6 is a graph showing the relationship between the depth from the outer surface OF of the mold D after the surface treatment and the hardness of the mold D. In the mold D after the surface treatment, the hardness of the portion from the outer surface OF to the depth of about 100 μm to about 120 μm is higher than the hardness of the deeper portion. Therefore, in the mold D, the thickness of the portion whose hardness is increased by the surface treatment of the outer surface OF, that is, the surface treatment depth of the outer surface OF is about 100 μm to 120 μm.

  FIG. 7 is a graph showing the relationship between the depth from the inner surface IF of the mold D after the surface treatment and the hardness of the mold D. In the mold D after the surface treatment, the hardness of the portion from the inner surface IF to the depth of about 60 μm to about 80 μm is higher than the hardness of the deeper portion. Therefore, in the mold D, the thickness of the portion whose hardness is increased by the surface treatment of the inner surface IF, that is, the surface treatment depth of the inner surface IF is about 60 to 80 μm.

  Next, in order to evaluate the effect of the surface treatment of the outer surface OF and the inner surface IF of the mold D, a durability test was performed.

  FIG. 8 is a graph showing the elapsed time and the temperature of the mold D in the durability test of the outer surface OF of the mold D. The mold D is moved below the heating induction coil over about 2.5 seconds from the start of the durability test, and then the mold D is heated by the heating induction coil, and the temperature of the mold D is set to about 4.0 seconds. The temperature was raised to about 600 ° C. Thereafter, the mold D is moved from below the heating induction coil to below the water cooling nozzle over about 3.5 seconds, cooling water is supplied from the water cooling nozzle to cool the mold D, and the temperature of the mold D is set to 3 Reduced to about 20 ° C. in 0 seconds. The temperature raising and cooling cycle of the mold D was repeated over 6000 cycles.

  For comparison, by performing a surface treatment of the outer surface OF of the mold D under conditions different from the above-described surface treatment conditions, the mold D having a surface treatment depth of the outer surface OF of 60 μm or more and 80 μm or less; A mold D having a surface treatment depth of the outer surface OF of more than 80 μm and less than 100 μm was prepared. Then, a similar durability test was performed on these molds D.

  FIG. 9 is a schematic diagram of an apparatus for performing an endurance test on the inner surface IF of the mold D. First, a cylindrical test piece TP having the same dimension as the mold D and having the same size cooling hole CC is prepared, and the inner surface IF of the cooling hole CC of the test piece TP is prepared under the same conditions as the cooling hole CC of the mold D. Surface treatment was performed to prepare a test piece TP having an inner surface IF with a surface treatment depth of about 60 μm to 80 μm. For comparison, a test piece in which the inner surface IF of the test piece TP is subjected to a surface treatment under conditions different from the above-described surface treatment conditions, and the surface treatment depth of the inner surface IF is more than 80 μm and less than 100 μm. TP and a test piece TP of 100 μm or more and 120 μm or less were prepared.

  Next, a cooling device CL, an air blowing device AB, and an induction heating coil HT were prepared. And the front-end | tip part of each test piece TP was inserted in the induction heating coil HT about 80 mm in length from the front-end | tip, and it heated by the high frequency induction, and raised the temperature of the test piece TP to about 600 degreeC. Thereafter, the test piece TP is moved, the cooling pipe CP of the cooling device CL is inserted into the cooling hole CC of the test piece TP, the cooling water CW is allowed to flow through the cooling pipe CP, and the air A is blown from the air blowing device AB. The temperature of the test piece TP was lowered to 100 ° C. The cycle of heating and cooling of the test piece TP was repeated over 6000 cycles.

  FIG. 10 is an example of an enlarged cross-sectional photograph near the outer surface OF of the mold D. FIG. 11 is an example of an enlarged cross-sectional photograph near the inner surface IF of the test piece TP. In a predetermined evaluation length, the total crack length obtained by adding all the lengths L of the generated cracks was calculated, and the effect of the surface treatment of the outer surface OF of the mold D was evaluated. The evaluation results are shown in Table 1 below.

  Based on the total crack length of the outer surface OF of the mold D and the inner surface IF of the test piece TP, the surface treatment depth d determined as having a durability of 120,000 shots or more as the mold D for forging is good. (Circle mark in Table 1). Further, the surface treatment depth d determined as having a durability of not more than 60,000 shots as the forging die D is determined to be defective (x mark in Table 1), and the durability between good and defective The surface treatment depth d determined to have an intermediate was determined to be intermediate (Δ mark in Table 1).

  More specifically, when the surface treatment depth d of the outer surface OF of the mold D is 60 μm or more and 80 μm or less, many cracks are generated, and the total crack length is, for example, about 4.2 mm. On the other hand, when the surface treatment depth d of the outer surface OF of the mold D is 100 μm or more and 120 μm, the generation of cracks is suppressed, the total crack length is reduced by about 60%, and the total crack length is, for example, It stayed at about 1.8 mm.

  Further, when the surface treatment depth d of the inner surface IF of the cooling hole CC of the test piece TP corresponding to the inner surface IF of the mold D is 100 μm or more and 120 μm, many cracks are generated, and the total crack length is For example, it was about 23.1 mm. On the other hand, when the surface treatment depth d of the inner surface IF of the cooling hole CC of the test piece TP corresponding to the inner surface IF of the mold D is 60 μm or more and 80 μm or less, the generation of cracks is suppressed and the total crack length is reduced. Was reduced by 80% or more, and the total crack length remained at about 3.9 mm, for example.

  From the above evaluation results, the surface treatment depth d of the outer surface OF of the mold D is optimally about 100 μm or more and 120 μm or less, and the surface treatment depth of the inner surface IF of the mold D is about 60 μm or more and It has been found that 80 μm or less is optimal. The reason why the optimum surface treatment is different between the inner surface IF and the outer surface OF of the mold D is as follows.

  For example, in the mold D for forging, the outer surface OF of the mold D that forms the cavity needs to be heat cracked, that is, a process that is resistant to thermal shock. It is necessary to ensure the surface treatment depth d, which is a thickness of On the other hand, since the inner surface IF of the mold D inside the cooling hole CC needs to be resistant to corrosion cracking of the cooling water, the surface treatment is the thickness of the portion where the hardness of the inner surface IF of the mold D is high. If the depth d is deeper than necessary, cracks are likely to occur. Therefore, different surface treatments are required for the inner surface IF and the outer surface OF of the mold D.

  Here, the surface treatment apparatus 1 according to the present embodiment has a gas necessary for the surface treatment from the gas supply port 3 to the outer surface OF of the workpiece W accommodated in the processing furnace 2 such as the outer surface OF of the mold D. , And unnecessary gas in the processing furnace 2 can be discharged from the gas discharge port 4. Thereby, the surface treatment suitable for the outer surface OF of the workpiece W can be performed independently of the surface treatment of the inner surface IF of the workpiece W.

  Further, the gas pipe 5 is inserted into the internal space WI of the workpiece W such as the cooling hole CC of the mold D, and the gas pipe 5 is separated from the gas supply port 3 by the gas pipe controller 6. Therefore, the gas necessary for the surface treatment of the inner surface IF of the workpiece W can be appropriately supplied. In addition, the gas pipe control unit 6 switches between gas supply and discharge, and appropriately discharges unnecessary gas in the internal space WI of the workpiece W from the gas pipe 5 independently of the gas discharge port 4. be able to. Thereby, the surface treatment suitable for the inner surface IF of the workpiece W can be performed independently of the surface treatment of the outer surface OF of the workpiece W.

  Therefore, according to the surface treatment apparatus 1 of the present embodiment, even when the surface treatment conditions of the inner surface IF facing the inner space WI of the workpiece W and the outer surface OF of the workpiece W are different, the inner surface The surface treatment of the IF and the outer surface OF can be performed appropriately. Thereby, for example, the surface treatment depth of the outer surface OF of the forging die D can be approximately 100 μm or more and 120 μm or less, and the surface treatment depth of the inner surface IF can be approximately 60 μm or more and 80 μm or less, It becomes possible to prolong the life of the mold D as compared with the prior art.

  On the other hand, with the conventional surface treatment method and surface treatment apparatus, it is difficult to perform optimum surface treatment on the inner surface and the outer surface of the mold. For example, as shown in Table 1, when the optimal surface treatment is performed on the outer surface of the mold, cracks are likely to occur on the inner surface, and when the optimal surface treatment is performed on the inner surface of the mold, Cracks are likely to occur. Therefore, in the conventional surface treatment method and the surface treatment apparatus 1, it is difficult to extend the life of the mold.

  The embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

DESCRIPTION OF SYMBOLS 1 Surface treatment apparatus 2 Processing furnace 3 Gas supply port 4 Gas exhaust port 5 Gas pipe line 6 Gas pipe line control part W To-be-processed object WI Internal space

Claims (1)

A surface treatment apparatus comprising a processing furnace for storing an object to be processed, a gas supply port for supplying gas to the processing furnace, and a gas discharge port for discharging gas from the processing furnace,
A gas pipe inserted into the internal space of the workpiece;
A gas line control unit that switches between supply of gas to the gas line and discharge of gas from the gas line independently of supply of gas to the gas supply port and discharge of gas from the gas discharge port A surface treatment apparatus comprising:

Images