JP6970942B2 - Heat treatment method for iron-based molded products - Google Patents

Description

The present invention relates to a heat treatment method for an iron-based molded product.

Iron-based sintered bodies obtained by molding and sintering iron-based powder such as iron powder are used in various parts such as automobiles and industrial machines. Generally, an iron-based sintered body is manufactured by compression-molding a raw material powder containing an iron-based powder to produce an iron-based green compact and sintering the raw material powder. In addition, heat treatment such as quenching may be performed after sizing or machining after sintering.

Conventionally, when an iron-based green compact is sintered or an iron-based sintered body is heat-treated such as by quenching, the iron-based green compact or an iron-based sintered body (hereinafter collectively referred to as "iron-based molded body"). It is known that a plurality of (there are) are arranged side by side and heat-treated collectively while maintaining the state. For example, in Patent Document 1, an adhesive is applied to the surface (end face) of a molded body, a plurality of molded bodies are stacked, and the molded bodies are adhered to each other, and then transferred to a sintering furnace for sintering. Is disclosed.

Japanese Unexamined Patent Publication No. 2016-89254

When heat-treating an iron-based molded body, it is desirable to heat-treat the iron-based molded body in a state where a plurality of iron-based molded bodies are aligned. As disclosed in Patent Document 1, when a method of sintering a plurality of molded bodies in a stacked state is adopted, it is advantageous in terms of production efficiency. However, in this case, the posture of the stacked molded bodies may change or the stacked state may collapse due to vibration or the like when the molded bodies are stacked in a stack or when the molded bodies are carried into the heat treatment furnace in a stacked state. It may happen. If the posture of the molded product is displaced or the load is collapsed, the molded product may be deformed during sintering, or may be damaged such as chipped or cracked. Generally, vibration is unlikely to occur in the heat treatment furnace, and once the molded product enters the furnace, the vibration is reduced.

Patent Document 1 proposes that the molded bodies are adhered to each other with an adhesive to prevent the load from collapsing. However, when an adhesive is used, the amount and position of the adhesive to be applied are appropriate. Need to be managed. For example, if the amount of the adhesive applied is too small, sufficient adhesive strength may not be obtained, or if the amount of the adhesive applied is too large or the coating position shifts, the adhesive may squeeze out or drip. In particular, when the contact surface between the stacked molded bodies is small, the amount of the adhesive applied is small and the position where the adhesive is applied tends to shift, so it is difficult to sufficiently bond the molded bodies with the adhesive, and stacking is performed. It becomes difficult to maintain the stacked state at times and during transportation.

One of the objects of the present disclosure is to provide a heat treatment method for an iron-based molded body, which can stably maintain an aligned state of the iron-based molded body when the iron-based molded body is heat-treated.

The heat treatment method for the iron-based molded article of the present disclosure is as follows.
A method for heat-treating an iron-based compact obtained by compression-molding a raw material powder containing an iron-based powder or an iron-based compact that is an iron-based sintered body obtained by sintering the iron-based compact.
The magnetization step of magnetizing the iron-based molded body and
An alignment step of arranging the magnetized iron-based molded bodies and aligning a plurality of the iron-based molded bodies in a predetermined state.
The present invention comprises a heat treatment step of heat-treating a plurality of the iron-based molded bodies in an aligned state.

The heat treatment method for the iron-based molded body can stably maintain the aligned state of the iron-based molded body when the iron-based molded body is heat-treated.

It is a schematic perspective view which shows an example of an iron-based molded body. It is a schematic diagram explaining an example of the magnetization process in the heat treatment method of the iron-based molded article which concerns on embodiment. It is a schematic side view which shows an example of the state in which a plurality of iron-based green compacts are stacked in the alignment step in the heat treatment method of the iron-based molded body according to the embodiment. It is a schematic side view which shows an example of the state in which a plurality of iron-based sintered bodies are aligned with an alignment jig at intervals in the alignment step of the heat treatment method of the iron-based molded body according to the embodiment.

[Explanation of Embodiment of the present invention]
First, embodiments of the present invention will be listed and described.

(1) The heat treatment method for an iron-based molded product according to the embodiment of the present invention is
A method for heat-treating an iron-based compact obtained by compression-molding a raw material powder containing an iron-based powder or an iron-based compact that is an iron-based sintered body obtained by sintering the iron-based compact.
The magnetization step of magnetizing the iron-based molded body and
An alignment step of arranging the magnetized iron-based molded bodies and aligning a plurality of the iron-based molded bodies in a predetermined state.
The present invention comprises a heat treatment step of heat-treating a plurality of the iron-based molded bodies in an aligned state.

According to the heat treatment method for the iron-based molded body, by magnetizing and aligning the iron-based molded body, the aligned state of the iron-based molded body can be stably maintained by the magnetic force of the magnetized iron-based molded body. .. Therefore, when heat-treating a plurality of iron-based molded bodies in an aligned state, it is possible to perform the heat treatment while maintaining the aligned state. Therefore, the heat treatment method for the iron-based molded body can stably maintain the aligned state of the iron-based molded body when the iron-based molded body is heat-treated.

In the above-mentioned heat treatment method for iron-based molded bodies, the molded bodies are not adhered to each other by an adhesive as in the conventional case, so that the work of applying the adhesive can be omitted.

(2) As one aspect of the heat treatment method for the iron-based molded product, heating the iron-based molded product to _{a temperature of A 2} points or more in the heat treatment step can be mentioned.

By heating the magnetized iron-based molded body to _{a temperature of A 2} point (Curie point) or higher, the magnetization can be lost and the influence of the magnetization after the heat treatment can be eliminated. Generally, the heat treatment temperature at the time of sintering an iron-based green compact or quenching an iron-based sintered body is A ₂ points or more (A ₂ points of iron: about 770 ° C.). For example, the sintering temperature of the iron-based green compact is 1100 ° C. or higher, and the quenching temperature of the iron-based sintered body is 800 ° C. or higher.

(3) One aspect of the heat treatment method for the iron-based molded body is to magnetize the iron-based molded body so that the residual magnetic flux density is 0.3 T or more in the magnetization step.

By magnetizing the iron-based molded body so that the residual magnetic flux density is 0.3 T or more, the magnetic force of the magnetized iron-based molded body is strong, and the aligned state of the iron-based molded body can be maintained more stably. .. When the residual magnetic flux density of the iron-based molded body is 0.3 T or more, it depends on the shape and size of the iron-based molded body, the facing area between the iron-based molded bodies, etc. It is possible to apply a magnetic force of less than 1 kg. The larger the residual magnetic flux density of the iron-based molded body, the stronger the magnetic force tends to be, and it is easy to obtain the effect of stably maintaining the aligned state of the iron-based molded body. The upper limit of the residual magnetic flux density is not particularly limited, but is, for example, 0.8 T or less. When the iron-based molded body is a soft magnetic material such as pure iron, it is difficult to obtain a residual magnetic flux density of more than 0.8 T even if it is magnetized.

(4) As one aspect of the heat treatment method for the iron-based molded product, a magnetic field of 3978.9 A / m or more is applied to the iron-based molded product in the magnetization step.

By applying a magnetic field to the iron-based molded body, the iron-based molded body can be magnetized. The strength of the magnetic field applied to the iron-based molded body is 3978.9 A / m (50 Oe (1 Oe = 79.578 A / m)) or more, more preferably 7957.8 A / m (100 Oe) or more. The molded body reaches the saturation magnetic flux density, and the iron-based molded body can be sufficiently magnetized.

(5) As one aspect of the heat treatment method for the iron-based compact, when the iron-based compact is the iron-based compact, the magnetized iron-based compact is stacked and aligned in the alignment step. In the heat treatment step, sintering may be performed in a state where a plurality of the iron-based green compacts are stacked.

In the above aspect, a plurality of iron-based green compacts are stacked and aligned, and sintered in that state. By stacking the magnetized iron-based green compacts, the stacked iron-based green compacts can be attracted to each other by a magnetic force, and the stacked state of the iron-based green compacts can be stably maintained. Therefore, when sintering a plurality of iron-based green compacts in a stacked state, it is possible to sinter while maintaining that state.

It is sufficient that at least one of the stacked upper and lower iron-based compacts is magnetized, and the magnetized iron-based compact and the unmagnetized iron-based compact may be alternately stacked. Even in this way, the iron-based green compacts can be adsorbed to each other by the magnetic force of one of the magnetized iron-based green compacts. When all the iron-based green compacts to be stacked are magnetized iron-based green compacts, they are magnetized so that the facing surfaces of the iron-based green compacts are opposite to each other when they are stacked. In this case, since the iron-based green compacts attract each other, the magnetic attraction between the iron-based green compacts becomes stronger than when only one of them is magnetized. Therefore, the stacked state of the iron-based green compact can be maintained more stably.

(6) As one aspect of the heat treatment method for the iron-based molded body, when the iron-based molded body is the iron-based sintered body, the magnetized iron-based sintered body is made of a magnetic material in the alignment step. The iron-based sintered bodies may be attracted to an alignment jig to be aligned at intervals, and the plurality of iron-based sintered bodies may be baked at intervals in the heat treatment step. ..

In the above aspect, a plurality of iron-based sintered bodies are aligned on an alignment jig at intervals and quenched in that state. For example, in the case of an annular iron-based sintered body having a through hole formed in the center, a through hole of the iron-based sintered body is inserted through a rod-shaped aligning jig arranged in a horizontal direction, and a plurality of irons are inserted in the aligning jig. The system sintered body may be suspended and aligned. When quenching, if adjacent iron-based sintered bodies are close to each other or in contact with each other, the iron-based sintered bodies cannot be cooled uniformly, and the contact portion is not rapidly cooled and martensitic transformation is difficult. , Quenching may be incomplete. Therefore, the hardened iron-based sintered body is likely to be deformed, and the structure of the iron-based sintered body tends to be non-uniform. By aligning the magnetized iron-based sintered body with an alignment jig made of magnetic material, the iron-based sintered body is attracted to the alignment jig by magnetic force, and a plurality of iron-based sintered bodies are spaced apart from each other. Can be held stably at. Therefore, when a plurality of iron-based sintered bodies are quenched in a state of being spaced apart, it is possible to quench while maintaining the state. Here, the "magnetic material" is a material having the property of a ferromagnet, and examples thereof include iron-based materials such as iron or iron alloys (eg, cast iron).

If the facing surfaces of adjacent iron-based sintered bodies are arranged so as to have the same poles, the iron-based sintered bodies repel each other, so that they can be prevented from coming into close contact with each other or coming into contact with each other. It is easier to maintain the distance between the units.

[Details of Embodiments of the present invention]
Specific examples of the heat treatment method for the iron-based molded article according to the embodiment of the present invention will be described below with reference to the drawings. The same reference numerals in the figure indicate the same names. The present invention is not limited to these examples, and is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

<Heat treatment method for iron-based molded body>
The method for heat-treating an iron-based molded body according to an embodiment is a method for heat-treating an iron-based molded body (iron-based powder or iron-based sintered body), and includes the following steps.
1. 1. Magnetization process: Magnetizes an iron-based molded body.
2. 2. Alignment step: A plurality of iron-based molded bodies are aligned in a predetermined state.
3. 3. Heat treatment step: Heat treatment is performed in a state where a plurality of iron-based molded bodies are aligned.
One of the features of the heat treatment method for the iron-based molded body according to the embodiment is that the magnetized iron-based molded bodies are aligned and heat-treated in a state where a plurality of iron-based sintered bodies are aligned. Hereinafter, the heat treatment method for the iron-based molded article of the embodiment will be described in detail.

(Iron-based molded body)
The iron-based molded body is an iron-based green compact or an iron-based sintered body. The iron-based green compact is a compression-molded raw material powder containing an iron-based powder. For example, using a die having a die having a die hole and an upper punch and a lower punch arranged above and below the die, the die hole is filled with raw material powder and punched from above and below by a press machine. For example, the raw material powder is compressed and molded. The surface pressure during compression molding may be, for example, 600 MPa or more, and further 1000 MPa or more. The upper limit of the surface pressure is not particularly limited, but may be, for example, 1200 MPa or less.

The iron-based sintered body is obtained by sintering iron-based green compact, and examples thereof include sintering at a temperature of 1100 ° C. or higher and 1400 ° C. or lower. The iron-based sintered body may be subjected to heat treatment such as quenching in order to adjust properties such as hardness after sizing or machining after sintering.

The iron-based powder used as the raw material powder is a main material constituting an iron-based pressure powder (iron-based sintered body), and is an iron or an iron alloy powder containing iron as a main component. Here, "as a main component" means that the element is contained in an amount of more than 50% by mass, preferably 80% by mass or more, and further 90% by mass or more as a constituent component. Examples of the iron alloy include containing at least one alloying element selected from Cu, Ni, Sn, Cr, Mo and C. Of the above alloying elements, the total content of Cu, Ni, Sn, Cr and Mo is 0.5% by mass or more and 6.0% by mass or less, and further 1.0% by mass or more and 3.0% by mass or less. To do. The content of C may be 0.2% by mass or more and 2.0% by mass or less, and further 0.4% by mass or more and 1.0% by mass or less. Pure iron powder may be used as the iron-based powder, and the above-mentioned alloying element powder (alloyed powder) may be added. In this case, by sintering the iron-based green compact in a subsequent process, iron reacts with the alloying element to be alloyed.

The content of the alloying element is appropriately set so as to have a predetermined composition according to the use and specifications of the iron-based sintered body to be a product. As an example of the composition, Cu: 2.0% by mass and C: 0.8% by mass are contained, and the balance includes Fe and unavoidable impurities.

The average particle size of the iron-based powder is, for example, 20 μm or more, and further 50 μm or more and 150 μm or less. By setting the average particle size of the iron-based powder within the above range, it is easy to handle and compression molding is easy. The average particle size of the iron-based powder is the average particle size of the particles constituting the iron-based powder, and the particle size (D50) at which the cumulative volume in the volume particle size distribution measured by the laser diffraction type particle size distribution measuring device is 50%. ).

The shape of the iron-based molded body is, for example, a plate shape, an annular shape, a columnar shape, a cylindrical shape, or the like, depending on the intended use of the product. FIG. 1 shows an example of the shape of the iron-based molded body. The iron-based molded body 1 shown in FIG. 1 is used for a sprocket, has an annular shape with a through hole 10 formed in the center, and has gear teeth formed on the outer peripheral surface. The relative density of the iron-based molded product may be, for example, 85% or more, further 90% or more. The "relative density" here means the actual density (percentage of [measured density / true density]) with respect to the true density. The true density is the density of the iron-based powder constituting the iron-based molded product.

(Magnetization process)
The magnetization step is a step of magnetizing an iron-based molded body. As for the magnetization of the iron-based molded body, as shown in FIG. 2, a magnetic field may be applied to the iron-based molded body 1 by using a magnetizer 2 provided with a coil. In the example shown in FIG. 2, a magnetic field is applied so that the magnetic flux penetrates in the vertical direction (thickness direction) of the iron-based molded body 1 to magnetize the iron-based molded body 1. In this case, both end faces of the upper surface and the lower surface of the iron-based molded body 1 are magnetized so as to be opposite to each other.

In the magnetization step, the iron-based molded body may be magnetized so that the residual magnetic flux density is 0.3 T or more, and further 0.5 T or more. By setting the residual magnetic flux density of the iron-based molded body to 0.3 T or more, the magnetic force of the magnetized iron-based molded body becomes stronger. The upper limit of the residual magnetic flux density is not particularly limited, but is, for example, 0.8 T or less.

The magnetic field applied to the iron-based molded body may be in a state in which the iron-based molded body is magnetized (a state having a residual magnetic flux density), for example, 3978.9 A / m (50 Oe) or more, and further 7957.8 A / m (100 Oe). The above can be mentioned. By applying a magnetic field with a strength of 3978.9 A / m (50 Oe) or more to the iron-based molded body, the iron-based molded body can be sufficiently magnetized, and the magnetic force of the magnetized iron-based molded body can be strengthened. can. Specifically, the residual magnetic flux density of the iron-based molded product can be 0.3 T or more, and further 0.5 T or more. The stronger the applied magnetic field, the higher the residual magnetic flux density of the iron-based molded body. However, even if a magnetic field of a certain level or more is applied, the iron-based molded body is a soft magnetic material, so that the saturated magnetic flux density is reached. The residual magnetic flux density does not increase any more.

(Alignment process)
The alignment step is a step of arranging magnetized iron-based molded bodies and aligning a plurality of iron-based molded bodies in a predetermined state. As the alignment state of the iron-based molded body, in the case of sintering the iron-based green compact in the heat treatment step of the next step described later, it is possible to stack and align the magnetized iron-based green compact. In the case of quenching an iron-based sintered body, the magnetized iron-based sintered body is attracted to an alignment jig made of a magnetic material, and a plurality of iron-based sintered bodies are aligned at intervals. Can be mentioned. When the iron-based molded bodies are stacked and stacked, the number of stacking stages may be, for example, 2 or more and 10 or less, and further 6 or less, depending on the shape and size of the iron-based molded body.

By stacking the magnetized iron-based green compacts, the stacked iron-based green compacts can be attracted to each other by a magnetic force, and the stacked state of the iron-based green compacts can be stably maintained. Therefore, it is possible to suppress the posture deviation and the load collapse of the iron-based green compact due to vibration and the like during stacking and transportation to the heat treatment process. When stacking and aligning a plurality of iron-based green compacts, as shown in FIG. 3, the iron-based green compacts 1G may be stacked in the same direction (attitude) in the vertical direction (thickness direction). In this case, when the iron-based compacts 1G are stacked, the upper and lower iron-based compacts 1G are magnetized so that the opposite end faces are opposite to each other, so that the iron-based compacts 1G have a magnetic force. As a result, they attract each other and the magnetic attraction becomes stronger. Therefore, the stacked state can be maintained more stably.

In the example shown in FIG. 3, it is assumed that all the stacked iron-based powders 1G are magnetized, but it is sufficient that at least one of the upper and lower iron-based powders 1G is magnetized, and the magnetized iron-based powders are magnetized. The body and the unmagnetized iron-based green compact may be alternately stacked. Even in such a case, the iron-based green compacts can be adsorbed to each other by the magnetic force of one of the magnetized iron-based green compacts.

When aligning a plurality of iron-based sintered bodies at intervals, an alignment jig made of a magnetic material is used. By aligning the magnetized iron-based sintered body with an alignment jig made of magnetic material, the iron-based sintered body is attracted to the alignment jig by magnetic force, and a plurality of iron-based sintered bodies are spaced apart from each other. Can be held stably at. Therefore, it is possible to suppress the misalignment of the iron-based sintered body due to vibration or the like during alignment with the alignment jig or during transfer to the heat treatment process. When arranging a plurality of iron-based sintered bodies on the aligning jig at intervals, as shown in FIG. 4, the through holes 10 of the iron-based sintered body 1S are arranged in the rod-shaped aligning jig 3 arranged in the horizontally direction. Is inserted, and a plurality of iron-based sintered bodies 1S are suspended and aligned on the alignment jig 3. The alignment jig 3 is made of, for example, cast iron.

In the example shown in FIG. 4, the iron-based sintered bodies 1S are aligned in the same direction and arranged on the alignment jig 3, but the opposing end faces of the adjacent iron-based sintered bodies 1S have the same poles. The iron-based sintered body 1S may be arranged by alternately changing the orientation. In this case, since the iron-based sintered bodies repel each other, it is possible to avoid close contact or contact with each other, and it becomes easier to maintain the distance between the iron-based sintered bodies.

(Heat treatment process)
The heat treatment step is a step of heat-treating a plurality of iron-based molded bodies in an aligned state. Examples of the heat treatment include sintering an iron-based green compact and quenching an iron-based sintered body. In the present embodiment, the iron-based molded body is magnetized and aligned, and the aligned state of the iron-based molded body can be stably maintained by the magnetic force of the magnetized iron-based molded body, so that the aligned state is maintained. It is possible to heat-treat it as it is. Specifically, when sintering an iron-based green compact, it is sintered in a state where a plurality of iron-based green compacts are stacked (see FIG. 3), and when the iron-based sintered body is quenched, a plurality of irons are used. The system sintered body is quenched in a state where it is aligned with an alignment jig at intervals (see FIG. 4).

In the heat treatment step, the iron-based molded product _{may be heated to a temperature of A 2} point (Curie point) or higher. By setting the heat treatment temperature to A ₂ points or more, the magnetization of the magnetized iron-based molded body disappears, and the influence of the magnetization after the heat treatment can be eliminated. As the heat treatment temperature of the iron-based molded body, in the case of sintering iron-based green compact, the sintering temperature may be, for example, 1100 ° C. or higher and 1400 ° C. or lower, and further 1200 ° C. or higher and 1300 ° C. or lower. .. When the iron-based sintered body is quenched, the quenching temperature may be, for example, 800 ° C. or higher and 1000 ° C. or lower, and further 840 ° C. or higher and 900 ° C. or lower.

{Action effect}
The heat treatment method for the iron-based molded body according to the above-described embodiment is to magnetize and align the iron-based molded body, thereby stably maintaining the aligned state of the iron-based molded body by the magnetic force of the magnetized iron-based molded body. be able to. Therefore, when heat-treating a plurality of iron-based molded bodies in an aligned state, it is possible to perform the heat treatment while maintaining the aligned state. For example, when sintering a plurality of iron-based green compacts in a stacked state, it is possible to sinter while maintaining that state. Alternatively, when a plurality of iron-based sintered bodies are quenched in a state of being spaced apart, it is possible to quench while maintaining that state.

In particular, when the iron-based molded body is magnetized so that the residual magnetic flux density is 0.3 T or more, the magnetic force of the magnetized iron-based molded body becomes stronger, so that the aligned state of the iron-based molded body is maintained more stably. be able to. Since the magnetic force required to stably maintain the aligned state of the iron-based molded body differs depending on the shape and size of the iron-based molded body, the facing area between the iron-based molded bodies, etc., the optimum residual of the iron-based molded body The magnetic flux density is different for each individual.

[Use of Embodiments of the present invention]
The heat treatment method for an iron-based molded body according to an embodiment of the present invention can be used, for example, for sintering an iron-based green compact or quenching an iron-based sintered body.

[Test Example 1]
Multiple iron-based green compacts are prepared, and when the iron-based green compact is magnetized and when it is not magnetized, the posture shift and load collapse when vibration is applied while the iron-based green compacts are stacked. The outbreak situation was evaluated.

(Preparation of iron-based green compact)
A raw material powder obtained by adding a lubricant to a commercially available pure iron powder (average particle size (D50): 130 μm) was compression-molded to prepare a sample of an iron-based pressure powder. The amount of the lubricant added was 0.5% by mass with respect to the total amount of the raw material powder. The shape of the produced iron-based green compact is an annular shape having an inner diameter of 35 mm, an outer diameter of 60 mm, and a thickness of 15 mm. The density (measured density) of the iron-based green compact was 6.98 g / cm ³ , and the relative density was 89%.

(Magnetization of iron-based green compact)
A magnetic field was applied to the prepared iron-based powder using a magnetizer equipped with a coil to magnetize the sample of the iron-based powder. The strength of the applied magnetic field is 1591.6 A / m (20 Oe), 3978.9 A / m (50 Oe), 7957.8 A / m (100 Oe), and each iron-based green compact magnetized by each magnetic field is sampled. It was designated as A, B, and C. Here, a magnetic field was applied so that the magnetic flux penetrated in the vertical direction (thickness direction) of the iron-based green compact. Further, the iron-based green compact that was not magnetized was used as sample D.

(Measurement of residual magnetic flux density)
The residual magnetic flux density of the iron-based powder when magnetized by each of the above magnetic fields was measured. The measurement of the residual magnetic flux density was based on JIS C 2552: 2014 (non-oriented electrical steel strip). Here, an annular iron-based green compact having an inner diameter of 20 mm, an outer diameter of 30 mm, and a thickness of 5 mm was used as a test piece for measurement, and the residual magnetic flux density when the test piece was magnetized by each magnetic field was obtained. .. The residual magnetic flux density was taken as the magnetic flux density when the magnetic field became zero after the magnetic field was applied by measuring the hysteresis curve when each magnetic field was applied to the test piece. The test piece for measurement differs only in size from the above-mentioned iron-based green compact sample, and has the same material and density. Table 1 shows the residual magnetic flux density when magnetized by each magnetic field.

(Evaluation of alignment status)
The magnetized iron-based powder (Samples A to C) and the non-magnetized iron-based powder (Sample D) are placed in the same vertical direction (thickness direction) without applying an adhesive. Stacked and stacked. Then, in a state where each iron-based green compact was stacked in 6 stages, vibration was applied during transportation in an actual production line, and the presence or absence of posture deviation and load collapse of the iron-based green compact was evaluated. Specifically, the rate of occurrence of misalignment and load collapse of the iron-based green compacts (defect occurrence rate) was determined by repeating the test of transporting each of the stacked iron-based green compacts on the actual production line. Examined. The results are shown in Table 1.

From the results in Table 1, the samples A to C in which the iron-based green compact was magnetized were able to reduce the occurrence of defects such as posture deviation and load collapse as compared with the non-magnetized samples D, and the stacked state was shown. It can be seen that it can be maintained stably. In particular, in the samples B and C having a magnetic field strength of 3978.9 A / m (50 Oe) or more, the residual magnetic flux density of the magnetized iron-based green compact can be set to 0.3 T or more, which causes a problem. It has been significantly reduced. When the samples A to C were sintered in a state where iron-based green compacts were stacked, they were not magnetized in the state after sintering.

[Test Example 2]
Positions when multiple iron-based sintered bodies are prepared and vibration is applied while the iron-based sintered body is suspended from an alignment jig depending on whether the iron-based sintered body is magnetized or not. The occurrence of deviation was evaluated.

(Preparation of iron-based sintered body)
The iron-based green compact prepared in Test Example 1 was sintered to prepare a sample of an iron-based sintered body.

(Magnetization of iron-based sintered body)
A magnetic field was applied to the prepared iron-based sintered body using a magnetizer equipped with a coil to magnetize the sample of the iron-based sintered body. The strength of the applied magnetic field was 3978.9 A / m (50 Oe), and the magnetized iron-based sintered body was used as sample E. Here, a magnetic field was applied so that the magnetic flux penetrates in the vertical direction (thickness direction) of the iron-based sintered body. Further, the iron-based sintered body that was not magnetized was used as sample F.

(Measurement of residual magnetic flux density)
The residual magnetic flux density of the iron-based sintered body when magnetized by the above magnetic field was measured. The measurement of the residual magnetic flux density is performed in accordance with JIS C 2552: 2014 (non-oriented electrical steel strip) as in Test Example 1, and here, the inner diameter is 20 mm, the outer diameter is 30 mm, and the thickness is as a test piece for measurement. An annular iron-based sintered body having a diameter of 5 mm was used. Then, the above magnetic field was applied to the test piece, the hysteresis curve was measured, and the residual magnetic flux density when the test piece was magnetized was obtained. The test piece for measurement differs only in size from the above-mentioned iron-based sintered body sample, and has the same material and density. As a result, the residual magnetic flux density of the test piece of the iron-based sintered body when magnetized by the magnetic field of 3978.9 A / m was 0.50 T.

(Evaluation of alignment status)
The magnetized iron-based sintered body (sample E) and the unmagnetized iron-based sintered body (sample F) were respectively suspended from a rod-shaped alignment jig and aligned. Specifically, 15 iron-based sintered bodies of Samples E and F are prepared, an alignment jig is inserted through the through holes of each iron-based sintered body, and the iron-based sintered body is inserted into the alignment jig. Were suspended and aligned at 5 mm intervals. The alignment jig is a rod-shaped body made of cast iron and having a diameter of 10 mm, and the effective length of the alignment jig is 30 cm. Further, in the sample E, the orientations of the iron-based sintered bodies were alternately changed so that the opposite end faces of the adjacent iron-based sintered bodies had the same poles. Then, the iron-based sintered body was suspended from the alignment jig and subjected to vibration during transportation in an actual production line, and the presence or absence of misalignment of the iron-based sintered body was evaluated.

After applying vibration, the presence or absence of contact between the iron-based sintered bodies was examined. As a result, in the sample E in which the iron-based sintered body was magnetized, there was no contact between the iron-based sintered bodies, whereas in the non-magnetized sample F, there were two contacts between the iron-based sintered bodies. rice field. When the sample E was quenched with the iron-based sintered body suspended from the alignment jig, it was not magnetized in the state after quenching.

1 Iron-based molded body 1G Iron-based green compact 1S Iron-based sintered body 10 Through hole 2 Magnetizer 3 Alignment jig

Claims (7)

A method for heat-treating an iron-based compact obtained by compression-molding a raw material powder containing an iron-based powder or an iron-based compact that is an iron-based sintered body obtained by sintering the iron-based compact.
The magnetization step of magnetizing the iron-based molded body and
An alignment step of arranging the magnetized iron-based molded bodies and aligning a plurality of the iron-based molded bodies in a predetermined state.
Bei example a heat treatment step of heat-treating in a state of aligning the plurality of the iron-base molded article, a,
The iron-based molded body is a soft magnetic material.
A method for heat-treating an iron-based molded body. The iron-based powder is an iron or iron alloy powder, and is
The method for heat-treating an iron-based molded product according to claim 1, wherein the iron alloy contains at least one element selected from Cu, Ni, Sn, Cr, Mo and C. In the heat treatment step, heating the iron-base molded article to a temperature above _two points A, a heat treatment method for iron-based molded article according to claim 1 or claim 2. In the magnetization process, the residual magnetic flux density of the iron-based molded body is magnetized so that the above 0.3 T, heat treatment method for iron-based molded article according to any one of claims 1 to 3. The heat treatment method for an iron-based molded body according to any one of claims 1 to 4 , wherein a magnetic field of 3978.9 A / m or more is applied to the iron-based molded body in the magnetization step. When the iron-based molded product is the iron-based green compact,
In the alignment step, the magnetized iron-based green compacts are stacked and aligned.
In the heat treatment step, sintering in a state of stacking a plurality of the iron-based powder compact, the heat treatment method of the iron-based molded article according to any one of claims 1 to 5. When the iron-based molded product is the iron-based sintered body,
In the alignment step, the magnetized iron-based sintered body is adsorbed on an alignment jig made of a magnetic material, and a plurality of the iron-based sintered bodies are aligned at intervals.
In the heat treatment step, quenching in a state spaced a plurality of said iron-based sintered body, the heat treatment method of the iron-base molded article as claimed in any one of claims 5.

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