JP5266910B2 - Heat treatment jig and heat treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such problems such that in the conventional nitriding-quenching treatment, when a treating temperature is made high, unevenness of ammonia concentration in a heat-treatment furnace becomes large and thus, unevenness of obtained surface hardness and hardened depth in each nitride-quenched product become large, and it is difficult to obtain the products having uniform quality. <P>SOLUTION: A heat treatment tool 2 which is used when the heat treatment of the workpieces W is carried out in the heating chamber 1b of a heating furnace 1, in which multiple workpieces W are placed and to which the ammonia gas is supplied and in which an internal atmosphere is heated with heaters 13, has wall plates 22, 22, ..., for covering the outer periphery of the side surfaces of the heat-treatment tool 2. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a heat treatment jig used when heat-treating the work in a heat-treatment furnace in which a plurality of works are placed, ammonia gas is supplied, and an internal atmosphere is heated by a heating tool, and the heat treatment The present invention relates to a heat treatment apparatus including a jig and the heat treatment furnace.

  Conventionally, a nitrogen-quenched product with a hardened layer formed on the surface of the workpiece can be obtained by infiltrating and diffusing nitrogen into the surface of the workpiece composed of iron-based materials such as iron and iron alloys and quenching. Has been done.

Specifically, the work is put into a heat treatment furnace and heated to a temperature at which the work can be quenched (a temperature at which a part or the whole of the work becomes an austenitic structure) (heating temperature is, for example, 700 degrees). More than about), ammonia gas or ammonia gas and nitrogen gas are supplied into the heat treatment furnace.
A pyrolysis reaction occurs in the ammonia gas supplied into the heat treatment furnace, and the atmosphere in the heat treatment furnace becomes a mixed atmosphere of ammonia, nitrogen, and hydrogen. By putting the workpiece into such a mixed atmosphere, Nitrogen diffuses from the surface of the workpiece.
Then, after diffusing nitrogen from the surface of the workpiece, the workpiece is quenched and quenched to obtain a nitriding and quenching product having a high surface hardness and a low internal altitude.
In addition, as a processing furnace which supplies ammonia gas in a furnace and nitrides a workpiece | work, there exists a thing as shown in patent document 1, for example.

  As described above, when nitrogen treatment is performed to diffuse nitrogen from the surface of the workpiece, the nitrogen concentration in the vicinity of the workpiece surface increases as nitrogen diffuses. In the vicinity, a nitrogen diffusion pattern as shown in FIG. 12 is formed. That is, the nitrogen concentration is the highest on the workpiece surface, and the nitrogen concentration decreases as the distance from the workpiece surface increases.

  Thereafter, by quenching, the workpiece surface having a high nitrogen concentration has a high hardness (for example, 700 Hv is obtained as a Vickers hardness in the case of FIG. 12), and the distance from the workpiece surface is lower than the workpiece surface at the depth of d1. (For example, in the case of FIG. 12, the Vickers hardness is 500 Hv), and the distance from the workpiece surface is d2 that is deeper than d1, and the hardness is even lower (for example, in the case of FIG. 12, the Vickers hardness is 400 Hv). ).

The characteristics of the obtained nitrocarburized product are the hardness of the workpiece surface (surface hardness) and the distance from the workpiece surface (curing depth) at which the specified hardness is obtained. In doing so, these two characteristic values or any one characteristic value is managed within a predetermined range.
The curing depth is the distance d1 when the predetermined hardness obtained is set to 500 Hv in the case shown in FIG.

In addition, as an index indicating the ease of diffusion of nitrogen to the workpiece surface, there is a nitriding potential in the furnace atmosphere. The higher the nitriding potential, the more the diffusion of nitrogen to the workpiece surface is promoted.
The nitriding potential is expressed by the following equation (1). In order to increase the nitriding potential and facilitate the diffusion of nitrogen to the workpiece surface, the partial pressure of ammonia gas in the furnace atmosphere is increased. It can be seen that it is effective to reduce the partial pressure of hydrogen gas.
P (N) = P (NH ₃ ) / {P (H ₂ ) ^3/2 } (1)

  As a method for increasing the surface hardness of the workpiece subjected to nitriding and quenching and increasing the curing depth, increasing the nitriding potential, increasing the treatment temperature of the nitriding treatment, and nitriding It is generally considered that there are three methods of increasing the processing time of processing.

The surface hardness of the workpiece increases as the nitrogen concentration on the workpiece surface increases. However, the increase in the nitrogen concentration on the workpiece surface can be achieved by increasing the nitriding potential or increasing the nitriding treatment time. it can.
However, if the nitrogen concentration on the workpiece surface becomes too high (about 1% or more), voids (voids) will be generated on the workpiece surface and cracks will occur in the obtained nitrocarburized product. May affect quality.

  Nitrogen treatment is performed at a lower ambient temperature than when carburizing is performed, so the penetration rate of nitrogen into the workpiece surface is slow. However, in order to obtain a large hardening depth, If the nitriding time is lengthened, voids are generated as described above, and it is difficult to obtain a large curing depth by these methods.

In order to increase the curing depth, it is effective to increase the treatment temperature of the nitriding treatment, but when the treatment temperature is increased, the variation in ammonia concentration in the heat treatment furnace increases.
When performing a nitriding quenching process, the process is performed with a large number of workpieces carried into the heat treatment furnace at once. Variations in hardness and curing depth increase, making it difficult to obtain a product with a constant quality.

JP-A-8-13123

  Therefore, in the present invention, when performing a nitriding quenching process on the workpiece, while suppressing the variation in ammonia concentration in the heat treatment furnace while increasing the treatment temperature in the heat treatment furnace, the generation of voids on the workpiece surface is suppressed. There is provided a heat treatment jig and a heat treatment apparatus capable of obtaining a nitriding and quenching product that has a high surface hardness and a large hardening depth and that has small variations in properties such as the hardening depth between workpieces. Is.

A heat treatment jig and a heat treatment apparatus for solving the above problems have the following characteristics.
That is, the heat treatment treatment used when heat-treating the work in a heat treatment furnace in which a plurality of works are placed, ammonia gas is supplied, and the internal atmosphere is heated by a heating tool. A side wall surface covering the outer periphery of the side surface of the heat treatment jig, and an opening having an area corresponding to the height of the ammonia concentration in the heat treatment furnace is formed in each part of the side wall surface. .
As a result, it is possible to suppress variations in the surface hardness and the curing depth of the nitrocarburized product obtained by subjecting each workpiece to a nitridation quenching process, and it becomes possible to obtain a product with a constant quality.
In addition, since only the atmosphere containing ammonia gas in which the thermal decomposition reaction has progressed to the same level flows into the heat treatment jig, it is possible to increase the treatment temperature during the nitriding treatment while suppressing variations in ammonia concentration. Thus, it is possible to obtain a nitrocarburized product having a high surface hardness and a large hardening depth while suppressing the generation of voids on the workpiece surface.

According to a second aspect of the present invention, an opening area reducing member for reducing the opening area of the upper surface is disposed on the upper surface of the heat treatment jig.
Thereby, the inflow of the atmosphere from the upper end surface of the heat treatment jig into the heat treatment jig is limited, and the inflow of the atmosphere from the lower side of the heat treatment jig can be promoted.

According to a third aspect of the present invention, the heat treatment jig is divided into a plurality of sections, and the outer periphery of the side surface of each section is covered with the side wall surface.
Thereby, it is possible to prevent the atmosphere from flowing into the heat treatment jig from the side surfaces of the respective sections, and to allow the atmosphere to flow from the lower surface of the heat treatment jig.
Therefore, the work in each section can be exposed to the atmosphere of the same ammonia concentration, and the variation in the surface hardness and the curing depth of the nitrocarburized product obtained by the nitriding and quenching process can be suppressed. Can be obtained.
In addition, since only the atmosphere containing ammonia gas in which the thermal decomposition reaction has progressed to the same level flows into each compartment, it is possible to increase the treatment temperature during the nitriding treatment while suppressing variations in ammonia concentration. It is possible to obtain a nitrocarburized product having a high surface hardness and a large hardening depth while suppressing the generation of voids on the workpiece surface.

According to a fourth aspect of the present invention, the side wall surface is a wall plate member attached to the main body of the heat treatment jig.
Thereby, the said side wall surface can completely cover the opening part of the side surface of the main body of a heat processing jig, and it becomes possible to prevent reliably that atmosphere flows in from the side surface of the said main body.

According to a fifth aspect of the present invention, the side wall surface is a plate-like member disposed between the main body of the heat treatment jig and a heating tool disposed in the heat treatment furnace.
As a result, it is possible to suppress variations in the surface hardness and the curing depth of the nitrocarburized product obtained by subjecting each workpiece to a nitridation quenching process, and it becomes possible to obtain a product with a constant quality.
In addition, since only the atmosphere containing ammonia gas in which the thermal decomposition reaction has progressed to the same level flows into the main body of the heat treatment jig, the treatment temperature during the nitriding treatment is increased while suppressing variations in ammonia concentration. It is possible to obtain a nitriding and quenching product having a high surface hardness and a large curing depth while suppressing generation of voids on the workpiece surface.

Further, as described in claim 6, the heat treatment jig is configured to be able to be transferred from the outside of the heat treatment furnace to the inside of the heat treatment furnace through a transfer port formed on one surface of the heat treatment furnace. A heating tool is installed on the outer side of the heat treatment jig conveyed in the heat treatment furnace in a direction orthogonal to the conveyance direction of the heat treatment jig, and the side wall surface includes the main body of the heat treatment jig and the heat treatment A first plate-like member arranged between the heating tool arranged in the furnace, and a second plate-like member arranged outside the heat treatment jig in the conveying direction of the heat treatment jig It is a member.
As a result, it is possible to suppress variations in the surface hardness and the curing depth of the nitrocarburized product obtained by subjecting each workpiece to a nitridation quenching process, and it becomes possible to obtain a product with a constant quality.
In addition, since only the atmosphere containing ammonia gas in which the thermal decomposition reaction has progressed to the same level flows into the main body of the heat treatment jig, the treatment temperature during the nitriding treatment is increased while suppressing variations in ammonia concentration. It is possible to obtain a nitriding and quenching product having a high surface hardness and a large curing depth while suppressing generation of voids on the workpiece surface.

Further, according to claim 7, the second plate-shaped member is disposed on the transport port side and the counter-transport port side with respect to the heat treatment jig, and is disposed on the transport port side. The member is configured to be able to open and close a conveyance path of the heat treatment jig.
Thereby, the main body can be carried into and out of the heat treatment furnace while the side surface of the main body of the heat treatment jig on the conveying port side is covered with the second plate-like member.

In addition, as described in claim 8, the side wall surface is made of molybdenum or tungsten .
As a result, even when the heat treatment jig is repeatedly heated and cooled, the side wall surface is not distorted or undulated so that the oil flow is less likely to be disturbed during quenching, and the distortion generated in the workpiece after quenching is prevented. Can be reduced.
Moreover, the lifetime of the said side wall surface can be extended.

Further, as described in claim 9, a heat treatment apparatus includes the heat treatment jig described in any one of claims 1 to 8, and the heat treatment furnace.
As a result, it is possible to suppress variations in the surface hardness and the curing depth of the nitrocarburized product obtained by subjecting each workpiece to a nitridation quenching process, and it becomes possible to obtain a product with a constant quality.
In addition, since only the atmosphere containing ammonia gas in which the thermal decomposition reaction has progressed to the same level flows into the heat treatment jig, it is possible to increase the treatment temperature during the nitriding treatment while suppressing variations in ammonia concentration. Thus, it is possible to obtain a nitrocarburized product having a high surface hardness and a large hardening depth while suppressing the generation of voids on the workpiece surface.

According to a tenth aspect of the present invention, a fan for stirring the atmosphere in the heat treatment furnace is provided in the heat treatment furnace, and the fan is repeatedly switched between the forward rotation drive and the reverse rotation drive during the heat treatment of the workpiece.
As a result, the ammonia concentration in the atmosphere in the heat treatment furnace can be made uniform as a whole, and uniform nitriding treatment can be performed on all workpieces in the heat treatment jig. Variations in hardness and curing depth can be suppressed as a whole, and a product with a constant quality can be obtained.

According to the present invention, it is possible to suppress variations in the surface hardness and the curing depth of a nitrocarburized product obtained by subjecting each workpiece to a nitriding and quenching treatment, and it becomes possible to obtain a product of constant quality. .
In addition, since only the atmosphere containing ammonia gas in which the thermal decomposition reaction has progressed to the same level flows into the heat treatment jig, it is possible to increase the treatment temperature during the nitriding treatment while suppressing variations in ammonia concentration. Thus, it is possible to obtain a nitrocarburized product having a high surface hardness and a large hardening depth while suppressing the generation of voids on the workpiece surface.

  Next, modes for carrying out the present invention will be described with reference to the accompanying drawings.

  The heat treatment apparatus shown in FIG. 1 includes a heat treatment furnace 1 and a heat treatment jig 2 on which a number of workpieces W made of iron or iron alloy are placed, and the heat treatment treatment with the workpieces W placed thereon. By carrying the tool 2 into the heat treatment furnace 1 and performing a heat treatment, nitrogen is permeated and diffused into the surface of the work W, and a nitriding quenching process is performed in which quenching is performed.

  Further, the heat treatment apparatus is provided with a transport rail 3, and when the heat treatment jig 2 is carried into the heat treatment furnace 1, the heat treatment jig 2 is configured to move along the transport rail 3. Yes.

  The heat treatment furnace 1 includes a front chamber 1a, a heating chamber 1b disposed continuously to the front chamber 1a, and a quenching oil tank 1c disposed below the front chamber 1a.

A first opening / closing door 15a is provided between the front chamber 1a and the outside, and a second opening / closing door 15b is provided between the front chamber 1a and the heating chamber 1b.
Further, in the heating chamber 1b, a heater 13 which is a heating tool for heating the inside of the heating chamber 1b, a fan 14 for stirring the atmosphere in the heating chamber 1b, and a gas such as ammonia gas in the heating chamber 1b. And a gas supply pipe 12 are provided.
Further, oil for rapidly cooling the workpiece W during quenching is stored in the quenching oil tank 1c.

Nitrogen quenching of the workpiece W is performed using the heat treatment furnace 1 configured as described above. When performing the nitrogen quenching processing, first, a plurality of workpieces W are placed on the heat treatment jig 2, The heat treatment jig 2 on which W is placed is moved along the transfer rail 3 and transferred into the front chamber 1a.
After the workpiece W is transferred to the front chamber 1a, the first opening / closing door 15a and the second opening / closing door 15b are closed to evacuate the front chamber 1a, and then the front chamber 1a is filled with nitrogen gas.

Next, the second opening / closing door 15b is opened, and the workpiece W is transported along the transport rail 3 from the front chamber 1a into the heating chamber 1b through the transport port 1d.
After the workpiece W is conveyed into the heating chamber 1b, the workpiece W is heated by heating the atmosphere in the heating chamber 1b with the heater 13. In this case, by stirring the atmosphere in the heating chamber 1b by the fan 14, the temperature and atmosphere of each part in the heating chamber 1b are made constant.
After the workpiece W is heated by the heater 13, ammonia gas (or ammonia gas and nitrogen gas) at a predetermined flow rate is supplied from the gas supply pipe 12 into the heating chamber 1b while maintaining the heating state.

That is, the nitriding treatment on the workpiece W in the heating chamber 1b is performed in an atmosphere of ammonia gas (or ammonia gas and nitrogen gas).
Further, when the nitriding process is performed on the workpiece W in the heating chamber 1b, the atmosphere in the heating chamber 1b is heated to a predetermined temperature by the heater 13, and the heating in the heater 13 causes the temperature in the heating chamber 1b to be a predetermined temperature. It is controlled by the control device 4 connected to the heat treatment furnace 1 so as to be maintained at a predetermined temperature only for the time.

When performing the nitriding treatment on the workpiece W, the heating of the heating chamber 1b by the heater 13 is performed so that the temperature of the workpiece W is, for example, about 800 ° C. or higher, particularly in the range of about 800 ° C. to about 850 ° C. Done. In the case of this example, the nitriding treatment is performed at a temperature of 810 ° C. or 830 ° C., for example.
In general, the nitriding treatment for the workpiece W is performed at a low temperature of 800 ° C. or less, but as in this example, the nitriding treatment is performed at a temperature exceeding 800 ° C. (preferably 810 ° C., more preferably 830 ° C.). By performing the above, it is possible to increase the surface hardness of the workpiece W and to increase the curing depth.

  The control device 4 operates the fan 14, conveys the workpiece W in the heat treatment furnace 1, opens / closes the first opening / closing door 15a and the second opening / closing door 15b, and supplies ammonia gas into the heating chamber 1b. Control such as.

When the heating of the workpiece W in the heating chamber 1b is completed, the second opening / closing door 15b is opened, the workpiece W is conveyed to the quenching oil tank 1c, and the workpiece W is immersed in the oil in the quenching oil tank 1c and rapidly cooled.
Thereby, the workpiece W is quenched, and a nitrocarburized product is obtained.

In addition, by quenching the nitriding work W, the austenite structure in the work W is martensite, but not all austenite structure is martensite, and some austenite structure remains. Will be.
When the austenite structure remains in the work W, aging deformation occurs, or when the amount of retained austenite structure is small, the surface hardness of the work W increases, and so-called sub-zero treatment may be performed after the quenching process. is there.
This sub-zero treatment is a treatment in which the workpiece W that has been subjected to quenching treatment is rapidly cooled to 0 ° C. or less immediately after quenching, and the retained austenite structure in the workpiece W is martensitic. In this example, for example, −80 ° C. The surface hardness of the workpiece W is improved by performing a cooling process.
Tempering is performed after the sub-zero processing performed in this way.

Further, the cooling temperature in the sub-zero treatment can be set to -120 ° C or -160 ° C.
When the surface hardness of the workpiece W when the sub-zero treatment is not performed is, for example, 600 Hv, when the sub-zero treatment is performed at −80 ° C., for example, the surface hardness increases to 630 Hv, and when the sub-zero treatment is performed at −120 ° C., for example, the surface When the hardness is increased to 650 Hv and the sub-zero treatment is performed at −160 ° C., for example, the surface hardness is increased to 670 Hv, the surface hardness of the workpiece W tends to increase as the cooling temperature decreases.

As shown in FIG. 2, the heater 13 provided in the said heating chamber 1b is arrange | positioned at the both-sides surface part in the heating chamber 1b, for example.
That is, the heater 13 is installed on both sides of the workpiece W (heat treatment jig 2) carried into the heating chamber 1b on both sides in the direction orthogonal to the workpiece conveyance direction.
Thereby, the workpiece | work W (heat processing jig | tool 2) in the heating chamber 1b will be heated from the both outer sides in the direction orthogonal to a workpiece conveyance direction.

The fan 14 is disposed in the vicinity of the ceiling surface of the heating chamber 1b, and the gas supply pipe 12 supplies a gas such as ammonia gas downward from a position near the fan 14 on the ceiling surface of the heating chamber 1b. Has been placed.
The fan 14 is configured to blow air to the side supplied from above or below.

Therefore, as shown in FIG. 2, the atmosphere blown outward by the fan 14 in the direction orthogonal to the workpiece transfer direction moves downward along the heaters 13 located on both sides of the heat treatment jig 2, and It flows to the heat treatment jig 2 side.
In this case, the atmosphere that has flowed to the heat treatment jig 2 side in the upper part of the heating chamber 1b passes above the heat treatment jig 2, and the atmosphere that has flowed to the heat treatment jig 2 side in the upper and lower intermediate parts in the heating chamber 1b is heat treatment. The atmosphere that reaches the side surface of the jig 2 and flows toward the heat treatment jig 2 in the lower part of the heating chamber 1 b wraps around the heat treatment jig 2.

The atmosphere that has passed above the heat treatment jig 2 in the upper part of the heating chamber 1b returns to the fan 14 side again.
Further, the atmosphere reaching the side surface of the heat treatment jig 2 in the upper and lower intermediate portions in the heating chamber 1b is such that the side surface of the heat treatment jig 2 is open and there is no member that shields the inside and the outside of the heat treatment jig 2. Then, it flows into the heat treatment jig 2 as it is.
Furthermore, the atmosphere that has flowed downward of the heat treatment jig 2 in the lower part of the heating chamber 1b rises and flows into the heat treatment jig 2 from the bottom surface of the heat treatment jig 2 that is open.

In this way, the nitriding treatment of the workpiece W placed in the heat treatment jig 2 is performed by the atmosphere flowing into the heat treatment jig 2 from the side surface or the bottom surface.
That is, nitrogen diffuses from the surface of the workpiece W toward the inside due to the atmosphere flowing into the heat treatment jig 2.

Here, the ammonia gas supplied into the heating chamber 1b heated to a high temperature undergoes a thermal decomposition reaction, but the atmosphere blown by the fan 14 is also in the process of moving downward from the upper part in the heating chamber 1b. Thermal decomposition proceeds.
Therefore, the lower atmosphere is in a state in which the thermal decomposition reaction has proceeded more than the upper atmosphere in the heating chamber 1b, and the lower ammonia concentration is lower than the upper ammonia concentration in the heating chamber 1b. Tend to be.
In particular, for the atmosphere descending along the vicinity of the heater 13, the pyrolysis reaction proceeds rapidly because the heater 13 is heated to a higher temperature than the atmosphere, and the lower ammonia concentration is lower than the upper ammonia concentration. The trend is remarkable.

  Therefore, when the atmosphere in the heating chamber 1b can flow into the inside of the heat treatment jig 2 from the upper part to the lower part on the side surface of the heat treatment jig 2, the fan 14 blows the air from the upper part in the heating chamber 1b. An atmosphere that moves downward along the heater 13 flows into the inside of the heat treatment jig 2 during the movement, and nitrogen diffuses from the surface of the workpiece W placed in the heat treatment jig 2. However, since the ammonia concentration in the lower atmosphere is lower than the ammonia concentration in the upper atmosphere, the workpiece W arranged in the upper portion and the workpiece W arranged in the lower portion in the heat treatment jig 2 Then, the curing depth and surface hardness will vary.

Therefore, the heat treatment jig 2 is configured as follows so that an atmosphere having a uniform ammonia concentration flows into the heat treatment jig 2.
For example, as shown in FIG. 3, the heat treatment jig 2 is configured by covering the outer periphery of the side surface of the jig body 21 with wall plates 22, 22.

As shown in FIG. 4, the jig body 21 includes, for example, a plurality of bottom plates 21 b, 21 b... Stacked in a plurality of stages (four stages in this example) at a predetermined interval, and each bottom plate 21 b, 21 b. Are supported by support columns 21a, 21a,.
Further, a top plate 21c is disposed on the upper end portion of the jig body 21 with a predetermined interval upward from the uppermost bottom plate 21b. The top plate 21c is supported by the support columns 21a, 21a,. It is supported.

  The top plate 21c is configured, for example, in a lattice shape in a posture in which a plurality of plate-like members are erected (a posture in which the plate surface faces in the front-rear and left-right directions), and has a large aperture ratio in the vertical direction. That is, in the top plate 21c, a portion other than the area occupied by the thickness of each plate-like member in the entire area in plan view is an opening.

  In addition, each of the bottom plates 21b, 21b,... Is configured by assembling plate-like members in a lattice shape, like the top plate 21c, or made of a mesh-like member, or made of punching metal. As with the top plate 21c, it has a large opening ratio in the vertical direction, and the atmosphere in the heating chamber 1b can be vented through the heat treatment jig 2 in the vertical direction.

  On each side surface of the jig main body 21, an area other than the area occupied by the thicknesses of the columns 21a, 21a, the bottom plates 21b, 21b,.

And the said heat processing jig | tool 2 adhere | attaches said wall board 22 * 22 ... comprised with a plate-shaped member on each side surface of the said jig | tool main body 21, and covers each said side surface.
Thereby, the said opening part of each side surface of the jig | tool main body 21 will be obstruct | occluded by wall board 22,22 ....

Accordingly, the inflow of the atmosphere blown by the fan 14 in the heating chamber 1b into the heat treatment jig 2 is as shown in FIG.
Specifically, the atmosphere that has flowed to the heat treatment jig 2 side in the upper part of the heating chamber 1b passes above the heat treatment jig 2 and returns to the fan 14 side again.
In addition, the atmosphere that has flowed to the heat treatment jig 2 side at the upper and lower intermediate portions in the heating chamber 1b reaches the side surface of the heat treatment jig 2, but the side surface of the heat treatment jig 2 is covered with the wall plates 22, 22. Since the opening is closed, the atmosphere reaching the side surface of the heat treatment jig 2 cannot flow into the heat treatment jig 2.

  Furthermore, the atmosphere that has flowed to the heat treatment jig 2 side in the lower part of the heating chamber 1b goes down to the heat treatment jig 2, and the atmosphere that has gone down rises to the bottom surface of the heat treatment jig 2 (located at the lowest level). Flows into the inside of the heat treatment jig 2 from the opening of the bottom plate 21b). The atmosphere that has entered the heat treatment jig 2 from below flows upward in the heat treatment jig 2, and is then discharged from the top plate 21c to the outside and returned to the fan 14 side.

  That is, during the nitriding treatment, the atmosphere in the heating chamber 1b that is supplied with ammonia gas and stirred by the fan 14 is prevented from flowing into the heat treatment jig 2 from the side surface of the heat treatment jig 2, It is possible to flow into the heat treatment jig 2 only from below the heat treatment jig 2.

  Thus, in the heat treatment jig 2, only the atmosphere existing in the lower part of the heating chamber 1b, that is, the atmosphere in which the thermal decomposition reaction of ammonia gas has progressed in the process of moving downward from the upper part of the heating chamber 1b. Therefore, each workpiece W placed in the heat treatment jig 2 is exposed to an atmosphere having the same ammonia concentration, and the nitriding reaction proceeds uniformly.

As a result, it is possible to suppress variations in the surface hardness and the curing depth of the nitrocarburized product obtained by subjecting each workpiece W to a nitridation quenching process, and it becomes possible to obtain a product with a constant quality.
In addition, since only the atmosphere containing ammonia gas in which the thermal decomposition reaction has progressed to the same level flows into the heat treatment jig 2, the treatment temperature during the nitriding treatment should be increased while suppressing variations in ammonia concentration. Thus, it is possible to obtain a nitrocarburized product having a high surface hardness and a large curing depth while suppressing the generation of voids on the surface of the workpiece W.

  Further, the wall plates 22, 22... Are attached to the jig main body 21 and completely cover the opening on the side of the jig main body 21. It is possible to reliably prevent the atmosphere from flowing in.

Moreover, as a material which comprises the said wall boards 22,22 ..., low thermal expansion metals, such as molybdenum and tungsten, can be used.
When the wall plates 22, 22... Are configured using iron-based materials such as iron and iron alloys, the thermal expansion coefficient of the wall plates 22, 22. By repeating the above, distortion and undulation are likely to occur in the wall plates 22, 22..., And the distortion and undulation increase.
When distortion or undulation occurs in the wall plates 22, 22..., After the nitriding treatment is performed on the work W, the heat treatment jig 2 is immersed in the oil in the oil tank 1 c. The flow of oil flowing into the heat treatment jig 2 is disturbed and becomes a turbulent flow.

As a result, the degree of cooling varies depending on the location of each workpiece W, and the workpiece W after quenching is distorted.
On the other hand, if the wall plates 22, 22... Are made of a low thermal expansion metal as described above, the wall plates 22, 22. Therefore, the oil flow is hardly disturbed during quenching, and the distortion generated in the workpiece W after quenching can be reduced.
Moreover, since distortion and waviness which generate | occur | produce in wall board 22,22 ... are small, even if it uses for a long period of time, since the big distortion will not be generated in the workpiece | work W after hardening, of wall board 22,22 ... Life can be extended.

Note that a top plate 21c configured by arranging plate-like members in a lattice pattern is disposed at the upper end of the heat treatment jig 2, and the opening area of the upper end surface of the heat treatment jig 2 is not provided with the top plate 21c. Compared to the case, it is smaller by the area occupied by the thickness of each plate-like member. That is, the top plate 21 c acts as an opening area reducing member that reduces the opening area of the upper surface of the heat treatment jig 2.
Thus, by arranging the top plate 21c and reducing the opening area of the upper end surface of the heat treatment jig 2, the inflow of the atmosphere from the upper end surface of the heat treatment jig 2 into the heat treatment jig 2 is limited. Inflow of the atmosphere from below the heat treatment jig 2 is promoted.

  Moreover, in the said heat processing jig | tool 2, although each side surface of the jig | tool main body 21 is completely block | closed with the wall plates 22,22 ... without an opening part, the said wall plates 22,22 ... As shown in FIG. 6, it can be made of a punching metal material having a predetermined opening area or a mesh material having a predetermined opening area.

That is, the flow of the atmosphere from the side surface of the heat treatment jig 2 is partially limited, and the flow of the atmosphere from the bottom surface of the heat treatment jig 2 is mainly used, so that the side surface of the heat treatment jig 2 Therefore, it is possible to suppress variation in the ammonia concentration of the atmosphere flowing into the heat treatment jig 2 as compared with the case where the atmosphere can flow in without limitation.
As a result, it is possible to obtain a product with a constant quality by suppressing variations in the surface hardness and hardening depth of the nitrocarburized product, while increasing the treatment temperature during the nitriding treatment while suppressing variations in the ammonia concentration. Thus, it becomes possible to obtain a nitriding and quenching product having a high surface hardness and a large curing depth while suppressing generation of voids on the surface of the workpiece W.

Moreover, the opening of the magnitude | size according to the height of the ammonia concentration in the atmosphere of the location corresponding to each site | part can also be formed in each site | part of the said wall boards 22,22 ....
For example, the wall plates 22, 22... Shown in FIG. 7 each have a plurality of vent holes 22 a, 22 a... Having a large opening area at the lower part, and the vent holes 22 a, 22 a. Are formed with a plurality of vent holes 22b, 22b,... Having no opening area, and no vent hole is formed in the upper part.

  That is, when the side surface of the heat treatment jig 2 is opened over the entire surface, an atmosphere with a high ammonia concentration flows in and an upper portion of the heat treatment jig 2 where the nitriding reaction easily proceeds and an atmosphere with a low ammonia concentration flows in The surface hardness and the curing depth of the obtained nitriding and quenching product vary depending on the lower part of the heat treatment jig 2 where the nitriding reaction is less likely to proceed than the upper part.

  On the other hand, the vent holes 22a, 22a, ... are formed in the lower part of the wall plates 22, 22, ..., the vent holes 22b, 22b, ... are formed in the upper and lower middle parts, and no vent hole is formed in the upper part. Thus, the flow into the upper part of the heat treatment jig 2 in an atmosphere with a high ammonia concentration is suppressed, the flow into the upper and lower middle parts of the heat treatment jig 2 with a medium ammonia concentration is allowed slightly, and the ammonia concentration is low. Inflow of the atmosphere into the lower part of the heat treatment jig 2 is allowed more than the upper and lower middle parts.

  As a result, the progress of the nitriding reaction at the upper part of the heat treatment jig 2 having a high ammonia concentration is suppressed, and the progress of the nitriding reaction at the lower part of the heat treatment jig 2 having a low ammonia concentration is promoted. The heat treatment jig 2 is made to proceed uniformly throughout.

  In this way, in the wall plates 22, 22,..., A portion corresponding to a portion where an atmosphere with a high ammonia concentration exists does not form a vent hole or a vent hole with a small area is formed to perform the nitriding reaction. The wall plates 22, 22,... Suppress the progress and form a large-area vent hole in a part corresponding to the part where the atmosphere having a low ammonia concentration exists to promote the progress of the nitriding reaction. The opening of the area corresponding to the height of the ammonia concentration in the heat treatment furnace 1 is formed at each part of the heat treatment furnace 1 so that the progress of the nitriding reaction in the heat treatment jig 2 is made uniform.

As a result, variations in the surface hardness and the curing depth of the obtained nitrocarburized product can be suppressed, and a product with a constant quality can be obtained.
Nitrogen-hardened products that can increase the processing temperature during nitriding while suppressing variations in ammonia concentration, and that have high surface hardness and large curing depth while suppressing the generation of voids on the surface of the workpiece W Can be obtained.

  In the wall plates 22, 22... Of the present example, in order to obtain an opening area corresponding to the high ammonia concentration, the air holes 22 a, 22 a. ···, but not limited to this, it is also possible to use a plate-like member made of a punching metal material or mesh material with different aperture ratios depending on the part as the wall plates 22 · 22 · · · is there.

Moreover, the heat processing jig | tool 2 can be comprised as follows.
For example, the heat treatment jig 30 shown in FIG. 8 includes a plurality of individual jigs 31, 31... And a plurality of individual jigs 31, 31. They are stacked (in this example, two rows and three columns arranged in one row are stacked in four steps).
A plurality or a single workpiece W is placed on each of the individual jigs 31, 31.

  Each of the individual jigs 31, 31... Is, for example, a jig formed by supporting a bottom plate and a top plate having a large opening area with a support in a state of being separated by a predetermined distance, as in the case of the heat treatment jig 2. Each side surface of the main body is covered with wall plates 31a, 31a,..., And the opening on the side surface of the jig body is closed by the wall plates 31a, 31a,.

And the heat processing jig | tool 30 is comprised by accumulating a plurality of individual jig | tool 31,31 ... with which the side surface was obstruct | occluded by wall board 31a.
That is, the heat treatment jig 30 is divided into a plurality of sections (one section corresponds to one individual jig 31), and the outer periphery of the side surface of each section is covered with the wall plates 31a, 31a,. It has been broken.

  As described above, even when the heat treatment jig 30 is divided into a plurality of sections, the atmosphere is prevented from flowing into the heat treatment jig 30 from the side surfaces of the individual jigs 31, 31. It is possible to allow the atmosphere to flow from the lower surface of the heat treatment jig 30 on which the bottom plates of the individual jigs 31, 31.

Therefore, in the heat treatment jig 30, the workpiece W in each individual jig 31, 31... Can be exposed to an atmosphere having the same ammonia concentration, and the surface hardness of the nitrocarburized product obtained by the nitriding quenching process Variations in the curing depth can be suppressed, and a product with a constant quality can be obtained.
In addition, since only the atmosphere containing ammonia gas in which the thermal decomposition reaction has progressed to the same level flows into each individual jig 31, 31... The treatment temperature can be increased, and a nitriding and quenching product having a high surface hardness and a large curing depth can be obtained while suppressing generation of voids on the surface of the workpiece W.

  Further, in the wall plates 31a, 31a, etc. of the individual jigs 31, 31 ..., the wall plates 31a, 31a, as in the case of the wall plates 22, 22 ... of the heat treatment jig 2, are used. Is formed with a ventilation hole having an area corresponding to the ammonia concentration at the site where the... Is disposed so that the progress of the nitriding reaction in each individual jig 31. Can do.

  This makes it possible to increase the treatment temperature during the nitriding treatment while suppressing variations in the ammonia concentration, and nitriding quenching with high surface hardness and a large hardening depth while suppressing the generation of voids on the surface of the workpiece W. In addition to obtaining a product, it is possible to obtain a product of a certain quality by suppressing variations in the surface hardness and the curing depth of the obtained nitrocarburized product.

  In addition, as said wall board 31a * 31a ..., the plate-shaped member which consists of a punching metal material, a mesh material, etc. which varied the opening ratio by the site | part by which this wall board 31a * 31a ... is arrange | positioned is used. Is also possible.

Moreover, the side wall surface which covers the side surface of the said heat processing jig 2 in which the some workpiece | work W is mounted can also be comprised as follows.
For example, in the heat treatment furnace 1 of the heat treatment apparatus shown in FIGS. 9 and 10, the first plate members 23 and 23 and the second plate members 24 and 24 are disposed in the heating chamber 1b.

Said 1st plate-shaped members 23 and 23 are plate-shaped members installed between the jig | tool main body 21 carried in to the heating chamber 1b, and the heater 13 arrange | positioned in the heating chamber 1b.
That is, the first plate-like members 23 and 23 are arranged at both outer positions in the direction orthogonal to the conveying direction of the jig main body 21 with respect to the jig main body 21, and the first plate-like members 23 and 23 are arranged. Thus, the outer periphery of the side surface in the direction orthogonal to the conveyance direction of the jig body 21 is covered.

The second plate-like members 24 and 24 are plate-like members disposed on both outer sides of the jig body 21 in the conveyance direction of the jig body 21.
That is, the second plate-like members 24 and 24 are disposed on the side of the transport port 1d and the side of the counter-transport port 1d in the transport direction of the jig main body 21 with respect to the jig main body 21. The members 24 and 24 cover the outer periphery of the side surface of the jig body 21 in the transport direction.

  As described above, the outer periphery of each side surface of the jig main body 21 conveyed into the heating chamber 1b where the nitriding treatment is performed is covered by the first plate-like members 23 and 23 and the second plate-like members 24 and 24. It has been broken.

Therefore, the flow of the atmosphere blown outward in the direction orthogonal to the conveying direction of the jig body 21 by the fan 14 in the heating chamber 1b is as shown in FIG.
Specifically, the atmosphere blown outward in the direction orthogonal to the conveyance direction of the jig body 21 moves downward along the heaters 13 located on both sides of the jig body 21, and further the heat treatment jig Flows to the 2 side.

In this case, the atmosphere flowing downward along the heater 13 flows in a space formed between the heater 13 and the first plate member 23.
The atmosphere that has flowed through the space flows to the jig body 21 side in the lower part of the heating chamber 1 b, and goes around the jig body 21.
In the lower part of the heating chamber 1 b, the atmosphere that has turned down below the jig body 21 rises and flows into the heat treatment jig 2 from the bottom surface of the jig body 21 that is open.

In addition, in the upper and lower intermediate portions in the heating chamber 1b, the atmosphere flowing through the space is prevented from flowing toward the jig body 21 by the first plate members 23 and 23.
Thus, the atmosphere blown by the fan 14 is prevented from flowing into the jig body 21 from the side surface of the jig body 21.

  Similarly, the atmosphere blown outward in the conveying direction of the jig body 21 by the fan 14 in the heating chamber 1b is prevented from flowing to the jig body 21 side by the second plate-like members 24 and 24. The atmosphere is prevented from flowing into the jig body 21 from the side surface of the jig body 21.

  That is, during the nitriding treatment, the atmosphere in the heating chamber 1b that is supplied with ammonia gas and stirred by the fan 14 is prevented from flowing into the jig body 21 from the side surface of the jig body 21; It is possible to flow into the jig main body 21 only from below the jig main body 21.

  Thus, in the jig body 21, only the atmosphere existing in the lower part in the heating chamber 1b, that is, the atmosphere in which the thermal decomposition reaction of ammonia gas has progressed in the process of moving downward from the upper part in the heating chamber 1b. Therefore, the workpieces W placed in the jig main body 21 are exposed to the atmosphere having the same ammonia concentration, and the nitriding reaction proceeds uniformly.

As a result, it is possible to suppress variations in the surface hardness and the curing depth of the nitrocarburized product obtained by subjecting each workpiece W to a nitridation quenching process, and it becomes possible to obtain a product with a constant quality.
Moreover, since only the atmosphere containing ammonia gas in which the thermal decomposition reaction has progressed to the same level flows into the jig main body 21, the treatment temperature during the nitriding treatment should be increased while suppressing variations in ammonia concentration. Thus, it is possible to obtain a nitrocarburized product having a high surface hardness and a large curing depth while suppressing the generation of voids on the surface of the workpiece W.

  In this example, only the jig body 21 is carried into the heating chamber 1b from the outside (as in the example shown in FIGS. 1 and 2, etc., on the outer periphery of the side surface of the jig body 21). (Not the heat treatment jig 2 with the wall plates 22, 22... Attached), and the role as a side wall surface corresponding to the wall plates 22, 22... In the example shown in FIGS. The one plate-like members 23 and 23 and the second plate-like members 24 and 24 are responsible.

  Further, in this example, in the first plate-like members 23, 23 and the second plate-like members 24, 24, as in the case of the wall plates 22, 22,... The first plate-like members 23 and 23 and the second plate-like members 24 and 24 can be formed by appropriately forming a vent hole or using a punching metal material or a mesh material having an opening ratio corresponding to the ammonia concentration. The opening area of each part can be changed according to the ammonia concentration.

Moreover, in the jig main body 21 carried into the heating chamber 1b in this example, a plate-like member (each of the jig main body 21 made of a punching metal material or a mesh material having a certain opening area is provided on each side surface. It is also possible to employ a configuration in which a plate-like member that does not completely block the side opening is provided.
Furthermore, in this example, the heat treatment jig 2 in a state where the wall plates 22, 22... Are attached to the jig main body 21 can be configured to be carried into the heating chamber 1 b.

Moreover, the 2nd plate-shaped member 24 arrange | positioned among the said 2nd plate-shaped members 24 and 24 in the said conveyance port 1d side in the conveyance direction of the jig | tool main body 21 is comprised so that raising / lowering is possible.
That is, the second plate-like member 24 on the transport port 1d side is lowered and positioned below the transport rail 3 (the state shown in FIG. 9), and is lifted and protrudes upward from the transport rail 3. It can be switched to a state.

The second plate-shaped member 24 covers the side surface of the jig body 21 when the second plate-shaped member 24 is in the raised state protruding upward from the transport rail 3, closes the opening of the side surface, and is positioned below the transport rail 3. When in the lowered state, the jig body 21 can be carried into and out of the heating chamber 1b.
In this way, by configuring the second plate-like member 24 on the conveyance port 1d side to be movable up and down, the jig main body 21 is covered with the second plate-like member 24 while covering the side surface on the conveyance port 1d side. 21 can be carried into and out of the heating chamber 1b.

In addition, the fan 14 that stirs the atmosphere in the heating chamber 1b is configured to repeatedly switch between normal rotation driving and reverse rotation driving every predetermined time during the nitriding treatment of the workpiece W.
If the fan 14 is continuously driven by normal rotation or reverse rotation, a flow in a certain direction tends to occur in the atmosphere in the heating chamber 1b. However, in the normal rotation and reverse rotation, By switching the driving repeatedly, the flow of the atmosphere in a certain direction is disturbed.

In this way, the forward and backward driving of the fan 14 is repeatedly switched to disturb the atmosphere flow in the heating chamber 1b, thereby causing variations in the ammonia concentration in the front-rear and left-right directions (horizontal direction) in the atmosphere in the heating chamber 1b. Can be reduced.
Thereby, it is possible to suppress variations in the surface hardness and the curing depth of the obtained nitrocarburized product, and it becomes possible to obtain a product with a constant quality.

Note that switching between forward rotation and reverse rotation of the fan 14 is particularly effective for reducing variations in the surface hardness and hardening depth of the nitrocarburized product in the front and rear, left and right directions (horizontal direction). .
On the other hand, covering the outer periphery of the side surface of the heat treatment jig 2 with the wall plates 22, 22..., The first plate members 23, 23, and the second plate members 24, 24, This is particularly effective for reducing variations in the surface hardness and the curing depth of nitriding and quenching products.

  Therefore, in addition to covering the outer periphery of the side surface of the heat treatment jig 2 with side wall surfaces such as the wall plates 22, 22..., The forward rotation drive and the reverse rotation drive of the fan 14 are repeatedly switched, The ammonia concentration of the atmosphere in the heating chamber 1b is made uniform as a whole, and it becomes possible to perform a uniform nitriding treatment on all the workpieces W in the heat treatment jig 2, and the surface of the obtained nitrocarburized product Variations in hardness and curing depth can be suppressed as a whole, and a product with a constant quality can be obtained.

Next, using the heat treatment jig 2 and the heat treatment furnace 1 configured as described above, the results of the case where the workpiece W is actually subjected to the nitriding and quenching treatment as in the following Examples 1 to 4 are illustrated. 11 will be used for explanation.
As the processing conditions of each example, the nitriding treatment was performed at a temperature of 830 ° C. using the heat treatment jig 2 on which the work W was placed in the upper and lower four stages.

  In the first embodiment, the side surface of the heat treatment jig 2 is closed with a wall plate having a predetermined size and a uniform opening ratio, and in the second embodiment, the treatment is performed on the side surface of the heat treatment jig 2. The aperture ratio is 0% for the first stage from the top with the high ammonia concentration, 20% for the second and third stages from the top, and 50% for the fourth stage from the top with the low ammonia concentration. In the third embodiment, the side surface of the heat treatment jig 2 is completely closed with a wall plate having an opening ratio of 0%, and the fan 14 is rotated in the normal direction. In the fourth embodiment, the side surface of the heat treatment jig 2 is completely closed with a wall plate having an aperture ratio of 0%, and the forward drive and reverse drive of the fan 14 are performed. -12 and after performing the nitriding quenching process, It was carried out subzero treatment at ℃ temperature.

  Thus, when the nitriding quenching process was performed for each Example, in Example 1, the surface hardness of the workpiece W was 600 ± 130 Hv. In addition, voids are generated on the surface of the workpiece that has been treated, and the larger the workpiece W located on the upper side of the heat treatment jig 2, the larger the void. Furthermore, the surface hardness of the workpiece W showed a lower value as it went from the upper side to the lower side of the heat treatment jig 2.

In Example 2, the surface hardness of the workpiece W was 640 ± 80 Hv. There were some voids on the treated workpiece surface, but there were few.
In Example 3, the surface hardness of the workpiece W was 620 ± 30 Hv. In the workpiece W in the heat treatment jig 2, no generation of voids was observed in all stages.
In Example 4, the surface hardness of the workpiece W was 655 ± 30 Hv. In the workpiece W in the heat treatment jig 2, no generation of voids was observed in all stages.

Comparing Example 1 with Example 2 and Example 3, it is found that the side wall surface covering the outer periphery of the side surface of the heat treatment jig 2 is provided and the forward drive and the reverse drive of the fan 14 are switched. It turns out that it has an effect with respect to the improvement of surface hardness, the dispersion | variation reduction of the surface hardness of the workpiece | work W, and generation | occurrence | production reduction of a void.
Further, when an opening having an area corresponding to the height of the ammonia concentration is formed on the side wall surface covering the outer periphery of the side surface of the heat treatment jig 2 (Example 2), no opening is formed (Example 3). ), The surface hardness of the workpiece W slightly decreases, but the variation in surface hardness is small.

  Further, when Example 3 and Example 4 are compared, the workpiece W is compared with the case where the sub-zero treatment is not performed (Example 3) by performing the sub-zero treatment after the nitriding quenching treatment (Example 4). It is possible to further increase the surface hardness of the workpiece W while maintaining the effects of reducing variations in the surface hardness of the steel and reducing the occurrence of voids.

  Further, when the nitriding treatment temperature is set to 810 ° C., the surface hardness obtained by the treatment under the conditions of Example 4 at the nitriding treatment temperature of 830 ° C., even if the treatment is performed under the conditions of Example 1 above. However, the curing depth at the nitriding temperature of 810 ° C. (for example, 0.19 mm) is the depth of curing at the nitriding temperature of 830 ° C. (for example, 0.19 mm). For example, it becomes shallower than 0.25 mm).

  The wall plates 22, 22..., The first plate members 23, 23 and the second plate members 24, 24 arranged on the outer periphery of the side surface of the heat treatment jig 2 described above, The effect of reducing variations in the surface hardness and hardening depth of the workpiece W by switching between normal rotation driving and reverse rotation driving, sub-zero processing, etc. can be achieved even when the nitriding temperature is low, but as the nitriding temperature increases. The effect of reducing variations in the surface hardness and hardening depth of the workpiece W is increased.

It is side surface sectional drawing which shows the heat processing furnace. It is front sectional drawing which shows the heating chamber of a heat treatment furnace. It is a perspective view which shows the heat processing jig | tool. It is a perspective view which shows the jig | tool main body and wall board in a heat processing jig | tool. It is front sectional drawing which shows the flow of the atmosphere in the heating chamber in which the heat processing jig | tool was carried in. It is a perspective view which shows the 2nd Example of the heat processing jig | tool. It is a perspective view which shows the 3rd Example of the heat processing jig | tool. It is a perspective view which shows the 4th Example of the heat processing jig | tool. It is side surface sectional drawing which shows the heat processing furnace provided with the 1st plate-shaped member and 2nd plate-shaped member which are arrange | positioned at the side surface outer periphery of the jig | tool main body in a heat processing jig. It is front sectional drawing which shows the heat processing furnace provided with the 1st plate-shaped member and 2nd plate-shaped member which are arrange | positioned at the side surface outer periphery of the jig | tool main body in a heat processing jig. It is a figure which shows the result of each Example which performed the nitriding quenching process with respect to the workpiece | work on various conditions. It is a figure which shows the relationship between the distance from the workpiece | work surface of the workpiece | work which performed the nitriding hardening process, and nitrogen concentration.

W Work 1 Heat treatment furnace 1a Front chamber 1b Heating chamber 1c Oil tank 1d Transfer port 2 Heat treatment jig 3 Transfer rail 12 Gas supply pipe 13 Heater 14 Fan 21 Jig body 21a Post 21b Bottom plate 21c Top plate 22 Wall plate 23 First plate shape Member 24 Second plate-like member 22a / 22b Vent 30 Heat treatment jig 31 Individual jig 31a Wall board

Claims (10)

A heat treatment jig used when heat-treating the work in a heat treatment furnace in which a plurality of works are placed, ammonia gas is supplied and an internal atmosphere is heated by a heating tool,
A side wall surface covering the outer periphery of the side surface of the heat treatment jig;
In each part of the side wall surface,
An opening having an area corresponding to the height of the ammonia concentration in the heat treatment furnace is formed,
A heat treatment jig characterized by that. An opening area reducing member for reducing the opening area of the upper surface is disposed on the upper surface of the heat treatment jig.
The heat treatment jig according to claim 1. The heat treatment jig is divided into a plurality of sections, and the outer periphery of the side surface of each section is covered with the side wall surface,
The heat treatment jig according to claim 1 or 2, wherein the heat treatment jig is provided. The side wall surface is a wall plate member attached to the main body of the heat treatment jig.
The heat treatment jig according to any one of claims 1 to 3, wherein the heat treatment jig is provided. The side wall surface is a plate-like member disposed between the main body of the heat treatment jig and a heating tool disposed in the heat treatment furnace.
The heat treatment jig according to claim 1 or 2, wherein the heat treatment jig is provided. The heat treatment jig is configured to be able to be conveyed from the outside of the heat treatment furnace to the inside of the heat treatment furnace through a conveyance port formed on one surface of the heat treatment furnace,
In the heat treatment furnace, a heating tool is installed at an outer position of the heat treatment jig conveyed into the heat treatment furnace in a direction perpendicular to the conveyance direction of the heat treatment jig,
The side wall surface includes a first plate-like member disposed between a main body of the heat treatment jig and a heating tool disposed in the heat treatment furnace, and the heat treatment treatment in the transport direction of the heat treatment jig. A second plate-like member disposed on the outer side of the tool,
The heat treatment jig according to claim 1 or 2, wherein the heat treatment jig is provided. The second plate-like member is disposed on the transport port side and the counter transport port side with respect to the heat treatment jig,
The second plate-like member disposed on the transfer port side is configured to be able to open and close the transfer path of the heat treatment jig,
The heat treatment jig according to claim 6. The side wall surface is made of molybdenum or tungsten .
The heat treatment jig according to any one of claims 1 to 7, wherein the heat treatment jig is provided. A heat treatment jig according to any one of claims 1 to 8, and the heat treatment furnace,
The heat processing apparatus characterized by the above-mentioned. In the heat treatment furnace, a fan for stirring the atmosphere in the heat treatment furnace is provided,
The fan is repeatedly switched between forward rotation driving and reverse rotation driving during heat treatment of the workpiece.
The heat treatment apparatus according to claim 9.

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