KR20120108017A - Degreasing method - Google Patents

Abstract

The present invention is a degreasing method for heating and degreasing wax contained in one or a plurality of treated articles in a furnace, wherein the temperature in the furnace is higher than an evaporation point at which wax evaporates and is lower than a temperature at which the treated article is carburized. By having a time hold | maintaining step, the quality nonuniformity for every processed product can be reduced.

Description

Degreasing method

The present invention relates to a degreasing method.

This invention claims priority based on Japanese Patent Application No. 2009-297251 for which it applied on December 28, 2009, and uses the content here.

In the sintering treatment, the binder is contained in the powder molded article by removing the binder (degreasing treatment) by heating the powder molded article molded into a predetermined shape by kneading an organic binder such as wax or a binder to the powder raw material (the degreasing treatment), followed by further raising the furnace temperature. To get the final product. As a heating furnace which performs this sintering process, the degreasing sintering furnace of following patent document 1 is mentioned, for example.

Patent Document 1: Japanese Patent Application Laid-Open No. 2000-17305

By the way, it is common that this kind of powder-molded article is bulk-processed of a small article, and it is common to arrange and accommodate in the inner box which consists of a shelf structure, and to load it into a furnace, as described in patent document 1. In order to achieve homogenization of the powder molded article, it is necessary to raise the temperature of all powder molded articles to the same degree and degreasing them.The difference in temperature between the outside of the inner box and the center side due to the difference in the arrangement position in the furnace, for example, the position of the heater. Occurs and a temperature difference occurs between the powder moldings. If a temperature difference occurs between the powder moldings, the time for degreasing ends is different and the degree of carburization of the product changes, resulting in uneven quality. Moreover, there is a method of gently raising the temperature in the furnace in order to reduce the temperature difference between the powder molded products, which is inefficient because it requires a long time until the start of degreasing treatment.

Moreover, not only the non-uniformity between these products, but also in the case where only one large powder molded product is degreased, if a temperature difference occurs for each part of the powder molded product, quality nonuniformity occurs for each part as well.

This invention is made | formed in view of the said problem, and an object of this invention is to provide the degreasing method of the powder molded article which can reduce the nonuniformity of the quality for every product, and the nonuniformity of the quality of each part of one product. Moreover, as a 2nd object, this invention aims at providing the degreasing method which can shorten processing time.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, the following method is employ | adopted in this invention. In other words,

(1) The present invention is a degreasing method of heating and degreasing an organic binder contained in one or a plurality of powder molded articles in a furnace, wherein the temperature in the furnace is higher than the evaporation temperature at which the organic binder evaporates and the powder molded article is carburized. It has a holding process which maintains predetermined time in a lower range.

In the present invention, by maintaining the temperature in the furnace for a predetermined time in the holding step, the expansion of the temperature difference between the powder molded article or the part of one powder molded article is suppressed, and the temperature difference is alleviated by heat conduction in the furnace. In addition, by maintaining the temperature in the furnace at a temperature higher than the evaporation temperature of the organic binder in the holding step, the organic binder can be reliably evaporated from the powder molded article, and the temperature lower than the temperature at which carburization by the gas generated by evaporation of the organic binder occurs. Generation of carburizing of the powder molded article can be suppressed.

(2) The degreasing method as described in said (1) may have a control process of adjusting the time of the said holding process based on the evaporation characteristic of the said organic binder.

By employing this method, the present invention can cope with the difference in temperature difference between the solid difference of the organic binder and the powder molded article, and can realize uniform degreasing between the powder molded articles.

(3) In the degreasing method as described in said (1) or (2), the 1st powder molded article and the 2nd powder molded article are arrange | positioned in the said furnace at least in different positions, and the temperature of the said 1st powder molded article is measured. It has a 1st measurement process and the 2nd measurement process which measures the temperature of the said 2nd powdered molded article, The temperature in the said furnace before the measurement result in the said 1st measurement process and the said 2nd measurement process reaches the said evaporation temperature. You may have a 2nd holding process which hold | maintains at the said evaporation temperature for a predetermined time.

By adopting this technique, in the present invention, the temperature in the furnace is maintained at the evaporation temperature of the organic binder until both the first powder molded article and the second powder molded article become the evaporation temperature of the organic binder, thereby maintaining the temperature between the powder molded articles approximately. After making it uniform, it raises the temperature to the temperature in a holding process. Therefore, even when the temperature difference between the temperature in the holding step and the evaporation temperature of the organic binder is relatively large, the organic binder is uniformly degreased between the powder molded articles, and the generation of carburization of the powder molded article by the gas generated by evaporation of the organic binder can be suppressed. Can be.

(4) The degreasing method as described in said (1) or (2) is a 1st measuring process which measures the temperature of the 1st position of the said powder molded article, and the temperature of a 2nd position different from the said 1st position of the said powder molded article. 2nd holding process which has a 2nd measurement process to measure, and maintains the temperature in the said furnace at the said evaporation temperature for a predetermined time, before the measurement result in the said 1st measurement process and the said 2nd measurement process reaches the said evaporation temperature. You may have

By employing this technique, in the present invention, by keeping the temperature in the furnace at the evaporation temperature until both the portion at the first position and the portion at the second position become the evaporation temperature of the organic binder in one powder molded article, After the temperature between parts of the powder molded article is made substantially uniform, the temperature rising to the temperature in the holding step is performed. Therefore, even when the temperature difference between the temperature in the holding step and the evaporation temperature of the organic binder is relatively large, generation of carburizing of the powder molded article by gas generated by uniform degreasing of the organic binder and evaporation of the organic binder between parts of one powder molded article Can be suppressed.

(5) The degreasing method as described in said (3) or (4) may have a temperature raising process which raises the temperature in the said furnace above the said evaporation temperature, before moving to a said 2nd holding process.

By employing this technique, in the present invention, if the temperature in the furnace is increased, the temperature increase rate of the powder molded article can be increased, so that the processing time can be shortened.

(6) The degreasing method as described in said (1)-(5) may have the pressure degree adjustment process which adjusts the atmospheric pressure in the said furnace.

By adopting this method, in the present invention, if the atmospheric pressure in the furnace is increased, the heat transfer property to the powder molded article is increased, so that the processing time can be shortened.

The present invention is a degreasing method for heating and degreasing an organic binder contained in one or a plurality of powder molded articles in a furnace, and can reduce the unevenness of the quality of each product of the powder molded article and the unevenness of each part of one product. The processing time of a powder molded article can also be shortened.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the degreasing furnace in embodiment of this invention.
It is a graph for demonstrating the degreasing method in 1st Embodiment of this invention.
It is a graph for demonstrating the degreasing method in 2nd Embodiment of this invention.
It is a graph for demonstrating the degreasing method in 3rd Embodiment of this invention.

EMBODIMENT OF THE INVENTION Hereinafter, the degreasing method in embodiment of this invention is demonstrated with reference to drawings. In addition, in the following description, the case where a wax is used for the organic binder kneaded with a powder raw material and used as a powder molded article is demonstrated.

FIG. 1: is a figure which shows the structure of the degreasing furnace 1 in embodiment of this invention.

The degreasing furnace 1 removes the wax contained in the processed product W (degreasing treatment) by heating the processed product W, which is a powder molded article containing wax (organic binder), under a reduced pressure and vacuum atmosphere. Furthermore, the furnace temperature is raised to sinter the processed product W to obtain a product. The degreasing furnace 1 has a furnace body 2 which consists of a vacuum container shaped in substantially cylindrical shape so that even if the pressure state in a furnace changes, it will be able to withstand the pressure. The furnace body 2 is provided with the water cooling jacket which is not shown in figure, and the temperature rise of the furnace body 2 is prevented.

In the furnace body 2, the processed goods W are heated via the accommodating shelf 3 accommodating the plurality of processed goods W, the mapple 4 surrounding the accommodating shelf 3, and the maffle 4. The heat insulation chamber 6 surrounding the heater 5, the maple 4, and the heater 5 is provided. In addition, the furnace body 2 includes a carrier gas supply system 7 for supplying carrier gas into the furnace body 2, a main exhaust system 8 for controlling atmospheric pressure in the furnace, and a degreasing exhaust system for exhausting wax vapor generated in the maple 4. (9) is connected. The degreasing furnace 1 has a control apparatus (not shown) which controls the drive of each said component apparatus.

The accommodating shelf 3 has a shelf structure provided with the some stage which accommodates several processed goods W. As shown in FIG. The receiving shelf 3 functions to form a heat conduction path that conducts heat of the heater 5 to the plurality of processed products W. The temperature sensor 51 which measures the temperature of the processed goods (1st powder molded article) W1 arrange | positioned at the corner part is provided in the corner part of the storage shelf 3 with the fastest temperature rising speed. Moreover, the temperature sensor 52 which measures the temperature of the processed goods (2nd powder molded article) W2 arrange | positioned at the center part of the storage shelf 3 is provided in the center part of the storage shelf 3 with the slow temperature rising speed, have. The measurement result of the temperature sensors 51 and 52 is output to a control apparatus. As the temperature sensors 51 and 52, a thermocouple is used here. For example, you may measure temperature using a non-contact sensor like a radiation thermometer.

Moreover, although this embodiment demonstrates the case where the several processed goods W are accommodated, when the processed goods W are one, the accommodating shelf 3 suitable for accommodating one processed goods W is mentioned. )

Further, the temperature sensors 51 and 52 are also appropriately arranged so as to measure the temperatures of the other portions (first position and second position) of one processed product W, respectively.

The heaters 5 are provided in pairs above and below the box-shaped maple 4. The heater 5 radiantly heats the maple 4 and indirectly heats the processed product W by the heat transmitted from the maple 4. The temperature of the heater 5 (temperature in the furnace) is managed by the control device.

As the heat insulation chamber 6, wool type heat insulating materials, such as a graphite wool and a ceramic wool, are used, for example. The heat insulation chamber 6 is box-shaped, and is provided so that the outer side of the maple 4 and the heater 5 may be enclosed.

The carrier gas supply system 7 has a carrier gas supply line 71 piped so that the carrier gas can be supplied into the furnace body 2. The carrier gas supplied from the carrier gas supply system 7 consists of inert gas, such as nitrogen gas, argon gas, helium gas, or their mixed gas. In addition, the carrier gas supply system 7 is provided with a pressure sensor (not shown) which can measure the atmospheric pressure in the furnace body 2. The measurement result of the pressure sensor is output to the control device.

The main exhaust system 8 has a main exhaust line 81 which is piped intakeably from the outside of the maple 4. The main exhaust line 81 is provided with a mechanical pump 82 and a rotary pump 83.

The mechanical pump 82 and the rotary pump 83 are driven in series or in a short term depending on the degree of the reduced pressure and vacuum atmosphere inside the muffle 4 under the control of the control device. In addition, the main exhaust system 8 is provided with a pressure sensor (not shown) which can measure the atmospheric pressure inside the maple 4. The measurement result of the pressure sensor is output to the control device.

The degreasing exhaust system 9 has a degreasing exhaust line 91 which is piped so that the wax vapor generated in the inside of the maple 4 can be inhaled. The degreasing exhaust line 91 is provided with a wax trap 92. The wax trap 92 recovers the wax by cooling the wax vapor.

In addition, the degreasing exhaust line 91 is connected with the main exhaust line 81 via the bypass line 93, and the intake of the wax vapor from the degreasing exhaust system 9 is performed by driving the rotary pump 83. do.

Next, the degreasing method of the processed product W using the degreasing furnace 1 of the said structure is demonstrated with reference to FIG.

It is a graph for demonstrating the degreasing method in 1st Embodiment of this invention. In FIG. 2, the vertical axis represents temperature and the horizontal axis represents time. 2, the solid line shows the temperature change of the furnace (heater 5), the dotted line shows the temperature change of the processed goods W1, and the dashed-dotted line shows the temperature change of the processed goods W2.

First, the main exhaust system 8 forms a vacuum atmosphere inside the maple 4. The evaporation point (evaporation temperature) Tv of the wax at this time is about 260 ° C as shown in FIG.

In step S1, the heater 5 is energized and the temperature in the furnace is raised from room temperature to the evaporation point Tv of the wax. At this time, the degree of heat transfer is different between the processed goods W1 and the processed goods W2 due to the difference in the arrangement position, and a temperature difference occurs.

Next, in step S2, the temperature in the furnace is maintained at the evaporation point Tv for a predetermined time before all the measurement results at the temperature sensors 51 and 52 reach the evaporation point Tv (second holding step).

In this step S2, the temperature in the furnace is maintained at the evaporation point Tv until both the processed product W1 and the processed product W2 are near the evaporation point Tv of the wax. Thereby, by making the temperature between the processed products W substantially uniform, it is set as the state which can start temperature rising to the temperature set in step S3 of degreasing process. For this reason, even if the temperature difference between the temperature of the processed product W and the evaporation point Tv of the wax in step S3 is relatively large, the wax can be uniformly degreased between the processed products W. In addition, it becomes possible to prevent the temperature of the processed product W from suddenly rising and being carbonized. Step S2 of this embodiment is complete | finished when all the measurement results of the temperature sensors 51 and 52 reach | attain the appropriate time to reach temperature T3 (T3 = Tv-20 degreeC).

Next, in step S3, the temperature in the furnace is maintained for a predetermined time within the range higher than the evaporation point Tv at which the wax evaporates and lower than the carbonization temperature at which the wax carbonizes (holding process).

In this step S3, while maintaining the temperature in the furnace for a predetermined time, the expansion of the temperature difference between the processed products W is suppressed, and degreasing is performed while alleviating the temperature difference by thermal conduction in the furnace.

Further, in step S3, after the temperature of the processed product W1 and the processed product W2 reaches T3, the gentle temperature raising process and the holding of gradually raising the temperature in the furnace to the holding temperature T2 (T2 = Tv + 30 ° C) are maintained. The maintenance process which maintains the temperature in a furnace at the temperature T2 is performed.

In step S3, the wax is evaporated from the treated product W by making the temperature in the furnace higher than the evaporation point Tv of the wax. When the temperature in the furnace is raised to the evaporation point Tv of the wax, the wax usually evaporates. However, if the temperature in the furnace is maintained at the evaporation point Tv due to the difference in the solid state of the wax, the difference in the temperature rise situation between the treated products W, or the like, a portion where the wax evaporates and a portion that does not evaporate will be generated. For this reason, in this embodiment, wax is reliably evaporated by maintaining the temperature in a furnace at temperature higher than the evaporation point Tv in step S3.

Moreover, in step S3, generation | occurrence | production of the carburization of the processed goods W is suppressed by maintaining the temperature in a furnace at the holding temperature T2 lower than the temperature which the processed goods W carburizes. In addition, the carburizing temperature of the processed product W is determined according to the kind of wax and the pressure in a furnace. The carburizing temperature of the processed product W of this embodiment is a temperature about 50 degreeC higher than the evaporation point Tv, for example. The holding temperature T2 is higher than the evaporation point Tv. If the temperature is too high, the treated product W is carburized, and if the holding temperature T2 is too close to the evaporation point Tv, the wax There is a possibility that it will not evaporate completely. In consideration of these points, the holding temperature T2 is set to Tv + about 30 ° C.

In addition, the evaporation of the wax is almost completed in the gentle temperature increase treatment, there is individual difference in the evaporation characteristics of the wax. Therefore, it cannot be said that the wax completely falls out from the processed product W after the gentle temperature increase treatment. On the other hand, in order to adjust the time of step S3, the maintenance process which maintains the temperature of a furnace at the holding temperature T2 at the end of step S3 is further provided (adjustment process). In this embodiment, the holding processing for one hour is performed.

Next, in step S4, the temperature in the furnace is raised from the holding temperature T2 to the sintering temperature T1 for sintering the processed product W.

Finally, in step S5, the temperature of the furnace is maintained at the sintering temperature T1 for a predetermined time until all the measurement results at the temperature sensors 51 and 52 reach the sintering temperature T1, and the processed product W is sintered. . By the above process, the homogenization of a product can be aimed at. In addition, the total processing time in this embodiment is 9.5 hours.

1st Embodiment mentioned above is a degreasing method which heats and degreases the wax contained in the processed goods W1 and the processed goods W2 (powder-molded goods) arrange | positioned at least in the furnace at different positions. According to this method, it has a step S3 (maintenance process) which maintains the temperature in the furnace for a predetermined time within a range higher than the evaporation point Tv at which the wax evaporates and lower than the temperature at which the processed product W is carburized. In this step S3, by maintaining the temperature in the furnace for a predetermined time, the expansion of the temperature difference between the processed products W or another part of one processed product W is suppressed, and the processed product W is heated by heat conduction in the furnace. The temperature difference between the liver or another part of one treatment product W is alleviated. In addition, in the holding | maintenance process of step S3, wax can be reliably evaporated from the processed product W by making temperature in a furnace higher than the evaporation point Tv of the wax (evaporation temperature of an organic binder). Moreover, generation | occurrence | production of carburization of the processed goods W can be suppressed by making temperature in a furnace into the temperature lower than the temperature which carburization by the gas which a wax generated evaporated occurs. Therefore, in 1st Embodiment of this invention, the nonuniformity of the quality of the product after completion can be reduced.

In addition, in the above-described first embodiment, by providing the adjusting step in step S3, it is possible to cope with the difference in the solid difference in wax or the temperature increase rate of the processed product W1 and the processed product W2, and uniform degreasing is performed between these processed products. It can be realized.

In addition, in 1st Embodiment, about the some processed goods W, the processed goods W1 (1st powder molded goods) and the processed goods W2 (2nd powder molded goods) are arrange | positioned at least in different positions, and the processed goods It has a 1st measuring process which measures the temperature of (W1), and a 2nd measuring process which measures the temperature of the processed goods W2. And before both the measurement result in a 1st measurement process and a 2nd measurement process has reached the evaporation temperature, it has a 2nd maintenance process which maintains the temperature in a furnace at this evaporation temperature for a predetermined time.

Therefore, the temperature of the processed product W1 and the processed product W2 is maintained by maintaining the temperature in the furnace at the evaporation temperature until both the processed product W1 and the processed product W2 become the evaporation temperature of the wax. After making it substantially uniform, it is set as the state which can start temperature rising to the temperature in a holding process. Therefore, even when the temperature difference between the temperature in the holding step and the evaporation temperature of the wax of the treated product W1 and the treated product W2 is relatively large, the wax is uniformly degreased between the treated product W1 and the treated product W2, Generation of carburization of the treated product W by the gas generated by evaporation of the wax can be suppressed.

In addition, in 1st Embodiment, about one processed goods W, the 1st measurement process of measuring the temperature of the 1st position of the other part of the processed goods W, and the 1st position of this processed goods W, Has a second measurement process of measuring the temperature at another second position. And before both the measurement result in a 1st measurement process and a 2nd measurement process has reached the evaporation temperature, it has a 2nd maintenance process which maintains the temperature in a furnace at this evaporation temperature for a predetermined time.

Thus, by keeping the temperature in the furnace at the evaporation temperature of the wax while both the portion of the first position and the portion of the second position in one treated product W become the evaporating temperature of the wax of the treated product W After the temperature between parts of one processed product W is made substantially uniform, the temperature rise to the temperature in the holding step is started. Therefore, even when the temperature difference between the temperature in the holding step and the evaporation temperature of the wax is relatively large, the wax is uniformly degreased between the portions of one processed product W, and the processed product W by the gas generated by evaporation of the wax. The occurrence of carburizing can be suppressed.

(Second Embodiment)

Next, a second embodiment of the present invention will be described. In the following description, the same code | symbol is attached | subjected about the component part same or equivalent to embodiment mentioned above, and the description is abbreviate | omitted or abbreviate | omitted.

It is a graph for demonstrating the degreasing method in 2nd Embodiment of this invention. As in the above embodiment, in the graph of FIG. 3, the vertical axis represents temperature and the horizontal axis represents time. 3, the solid line shows the temperature change of the furnace (heater 5), the dotted line shows the temperature change of the processed goods W1, and the dashed-dotted line shows the temperature change of the processed goods W2.

In 2nd Embodiment, in order to shorten processing time compared with the said embodiment, the atmospheric pressure in a furnace is adjusted and the evaporation point Tv of a wax is raised (pressure adjustment process). Increasing the atmosphere pressure in the furnace increases heat transfer to the processed product W, thereby reducing the processing time.

The adjustment of the atmospheric pressure in the furnace is performed by controlling the driving of the main exhaust system 8 and the driving of the carrier gas supply system 7. In the first embodiment, degreasing is performed in a vacuum atmosphere. In the second embodiment, the main exhaust system 8 is warmly operated, a predetermined amount of inert gas is supplied from the carrier gas supply system 7, and the pressure is higher than that in the vacuum atmosphere. Degreasing is performed under a reduced pressure atmosphere. As shown in FIG. 3, the evaporation point (Tv) of the wax of the second embodiment is about 350 ° C. Increasing the evaporation point (Tv) of the wax can increase the amount of heat input to the treated product (W) in steps S1 and S2. In addition, since the difference between the evaporation point Tv and the sintering temperature T1 decreases when the evaporation point Tv of the wax is increased, the time for raising the processed product W to the sintering temperature T1 in steps S4 and S5. Can shorten. In addition, the total processing time in this embodiment is 8.5 hours.

In the second embodiment of the present invention, by providing a pressure adjusting step in addition to the process described in the first embodiment, the processing time can be shortened because the atmospheric pressure in the furnace is increased and the heat transfer to the processed product W is increased. Do.

(Third Embodiment)

Next, a third embodiment of the present invention will be described. In the following description, the same code | symbol is attached | subjected about the component part same or equivalent to embodiment mentioned above, and the description is abbreviate | omitted or abbreviate | omitted.

It is a graph for demonstrating the degreasing method in 3rd Embodiment of this invention. In the graph of FIG. 4 as in the above embodiment, the vertical axis represents temperature and the horizontal axis represents time. In addition, in FIG. 4, the solid line shows the temperature change of the furnace (heater 5), the dotted line shows the temperature change of the processed goods W1, and the dashed-dotted line shows the temperature change of the processed goods W2.

In the third embodiment, in order to shorten the processing time than the first and second embodiments above, in addition to the method of the second embodiment, raising the temperature in the furnace above the evaporation point Tv before moving to step S2 (heating temperature). Process) (S1 ') is provided.

In step S1 ', the temperature in the furnace is raised to a temperature T4 higher than the evaporation point Tv at the initial temperature rise, and then the temperature is lowered to the evaporation point Tv. The temperature drop to the evaporation point Tv in step S1 'is stopped by the end of heating of the heater 5, and endotherm by the furnace atmosphere or a water cooling jacket. In this step S1 ', the heat input rate of the processed product W can be increased to increase the temperature increase rate, thereby reducing the processing time. In addition, since step S1 'is performed before step S2, the processed product W does not heat up than carburizing temperature. In addition, the temperature rise of the processed product W can be prevented beforehand in step S2. In addition, the total processing time in this embodiment is 7.9 hours.

In the third embodiment of the present invention, by providing the temperature raising step in addition to the process described in the first embodiment, the temperature in the furnace can be increased and the temperature increase rate of the processed product W can be increased, so that the processing time can be shortened. .

As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. The various shapes, combinations, etc. of each structural member shown in embodiment mentioned above are an example, It can change variously based on a design request etc. in the range which does not deviate from the well-known of this invention.

For example, in the above embodiment, it has been described that the process proceeds from step S1 to step S3 through step S2, but the present invention is not limited thereto, and for example, the process may proceed from step S1 to step S3 without going through step S2.

In addition, although the said embodiment demonstrated and demonstrated the wax as the organic binder contained in a powder molded article, this invention is not limited to this, It may be other types of organic binders, such as a binder.

Alternatively, the present invention can be applied not only to processing a plurality of processed products W but also to processing one processed product W. In this case, in the said embodiment, the temperature of the 1st powder molded article W1 and the 2nd powder molded article W2 is measured by the temperature sensors 51 and 52, respectively, and is processed. This process is performed by the portion of the first position (for example, the inside of the processed product W) and the portion of the second position (for example, the outside of the processed product W) in one processed product W. ), The temperature sensors 51 and 52 may be provided, respectively, and temperature measurement may be performed to perform the degreasing method of the present invention. Thereby, it becomes possible to reduce the nonuniformity of the quality for every part of one processed product W. As shown in FIG.

According to the degreasing method of this invention, the nonuniformity of the quality of each powdered article and the nonuniformity of the quality of each part of one product can be reduced, and the processing time of a powdered molded article can also be shortened.

S2 stage (second maintenance process)
S3 step (maintenance process)
S1 'step (heating process)
Tv evaporation point (evaporation temperature of organic binder)
W1 Treated Product (First Powder Molded Product)
W2 treated product (second powder molded article)

Claims (6)

A degreasing method for degreasing an organic binder contained in one or a plurality of powder molded articles in a furnace by heating,
And a holding step of maintaining the temperature in the furnace within a range higher than an evaporation temperature at which the organic binder evaporates and lower than a temperature at which the powder molded article is carburized. The method according to claim 1,
And a controlling step of adjusting the time of the holding step based on the evaporation characteristics of the organic binder. The method according to claim 1 or 2,
The first powder molded article and the second powder molded article are disposed in at least different positions in the furnace,
It has a 1st measuring process which measures the temperature of a said 1st powder molded article, and a 2nd measuring process which measures the temperature of a said 2nd powder molded article,
And a second holding step of holding the temperature in the furnace at the evaporation temperature for a predetermined time before both the measurement results in the first and second measuring steps reach the evaporation temperature. The method according to claim 1 or 2,
It has a 1st measurement process which measures the temperature of the 1st position of the said powder molded article, and a 2nd measurement process which measures the temperature of the 2nd position different from the said 1st position of the said powder molded article,
And a second holding step of holding the temperature in the furnace at the evaporation temperature for a predetermined time before both the measurement results in the first and second measuring steps reach the evaporation temperature. The method according to claim 3 or 4,
The degreasing method which has a temperature raising process which raises the temperature in the said furnace above the said evaporation temperature, before moving to a said 2nd holding process. The method according to any one of claims 1 to 5,
A degreasing method having a pressure adjusting step of adjusting the atmospheric pressure in the furnace.

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