JP2021100764A - Powder molding device - Google Patents

Abstract

To provide a powder molding device where the uniformity of the thickness of a powder molded body is improved.SOLUTION: A powder molding device 100 continuously forming a powder molded body comprises: a material supply part 15 having screws 4a, 4b transporting a powder material 101 in a rotary shaft direction by rotation driving; and a pressure molding part 16 which has rolls 12a, 12b disposed in parallel at a predetermined interval and where the powder material 101 supplied from the material supply part 15 by the rolls 12a, 12b is pressed and molded to a powder molded body 13. At least any one of the rolls 12a, 12b has a first surface 10 formed along the outer periphery of the rolls 12a, 12b and a second surface 20 formed at a part except the first surface 10 at a part positioning at both ends of the powder molded body 13 in an axial direction of the rolls 12a, 12b in the surfaces of the rolls 12a, 12b. The surface roughness of the first surface 10 is larger than that of the second surface 20.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an apparatus for molding powder.

By sintering a powder molded body obtained by pressure-molding a powder material such as ceramics or metal at a temperature equal to or lower than the melting point of the powder, a bond is formed between the powders to obtain a sintered body. Patent Document 1 discloses a powder molding machine in which a biaxial roll compression molding machine is installed in front of the outlet of the casing of the screw feeder, and the powder is forcibly fed to the compression molding machine by the screw feeder to perform compression molding. ing.

Japanese Patent No. 3335299

The powder molding machine described in Patent Document 1 still has room for improvement in terms of improving the uniformity of the thickness of the obtained powder molded product.

Therefore, an object of the present disclosure is to provide a powder molding apparatus having improved thickness uniformity of a powder molded body.

The powder molding apparatus according to the present disclosure is
A powder molding device that continuously produces powder molded products.
A material supply unit having a screw that conveys powder material in the direction of the rotation axis by being rotationally driven,
A pressure molding unit having a plurality of rolls arranged in parallel at predetermined intervals and pressurizing the powder material supplied from the material supply unit by the plurality of rolls to form the powder molded body.
With
At least one of the plurality of rolls is formed on the surface of the roll at a portion located at both ends of the powder molded product in the axial direction of the roll along the outer circumference of the roll. It has one surface portion and a second surface portion formed on a portion other than the plurality of first surface portions.
The surface roughness of the plurality of first surface portions is larger than that of the second surface portion.

According to the present disclosure, it is possible to provide a powder molding apparatus having improved thickness uniformity of a powder molded body.

It is a schematic diagram which looked at the powder molding apparatus of this disclosure from the top. FIG. 5 is a cross-sectional view taken along the line AA of the powder molding apparatus of FIG. It is a schematic view which looked at the pressure molding part of the powder molding apparatus of FIG. 1 from the outlet direction of a powder molded body. FIG. 3 is a cross-sectional view taken along the line BB of the pressure molding portion of the powder molding apparatus of FIG. FIG. 3 is a cross-sectional view taken along the line CC of the pressure molding portion of the powder molding apparatus of FIG. It is an enlarged view of the area D of FIG. It is a graph which shows the density distribution in the width direction of a powder compact by the difference in arrangement of the rough surface part on the surface of a roll.

(Background to the present invention)
By sintering a powder molded body obtained by pressure-molding a powder material of ceramics or metal at a temperature equal to or lower than the melting point of the powder, a bond is formed between the powders to obtain a sintered body. This is the main method of manufacturing ceramic products, ceramics, powder metallurgy, cermets and the like.

Examples of the method for producing a powder molded body for performing a sintering process include a method of pressurizing a powder material with a roll to form a sheet-shaped powder molded body, and a method of uniformly placing the powder material on a belt conveyor. After that, there is a method of forming a powder molded body by pressure molding with a stamping die and compression molding.

In the powder molded body formed by such a manufacturing method, the thickness may vary. If the thickness of the powder molded product varies, a sufficient load cannot be applied to the thin portion, and the thin portion is not sintered after the sintering process, resulting in an incomplete sintered body. It may end up. Therefore, it is desirable that the thickness of the powder molded product is uniform.

In the powder molding machine described in Patent Document 1, a biaxial roll compression molding machine is installed in the outlet direction of the casing of the screw feeder, and the powder is forcibly fed by the screw feeder to compression molding. Can be done.

However, the powder molding machine described in Patent Document 1 cannot uniformly bite the discharged powder material in the width direction of the roll. This is because the powder material discharged from the screw feeder receives friction from the inner wall of the screw feeder or the inner wall of the hopper, so that the flow velocity in the width direction of the roll is not constant. When rubbed by the inner wall of the screw feeder or the inner wall of the hopper, the flow velocity of the powder material slows down at both ends in the width direction of the roll, and the density of the powder compact produced by being pressurized by the roll is the width of the roll. It becomes smaller at both ends of the direction. As a result, a powder molded product having thin ends at both ends in the width direction of the roll is produced.

Therefore, the present inventors improve the uniformity of the thickness of the powder molded product by forming a portion having a large surface roughness at a portion located at the end portion of the powder molded product in the roll for molding the powder material. We devised a powder molding device to make it work, and devised the following configuration.

The powder molding apparatus according to one aspect of the present disclosure is
A powder molding device that continuously produces powder molded products.
A material supply unit having a screw that conveys powder material in the direction of the rotation axis by being rotationally driven,
A pressure molding unit having a plurality of rolls arranged in parallel at predetermined intervals and pressurizing the powder material supplied from the material supply unit by the plurality of rolls to form the powder molded body.
With
At least one of the plurality of rolls is formed on the surface of the roll at a portion located at both ends of the powder molded product in the axial direction of the roll along the outer circumference of the roll. It has one surface portion and a second surface portion formed on a portion other than the plurality of first surface portions.
The surface roughness of the plurality of first surface portions is larger than that of the second surface portion.

According to this configuration, it is possible to provide a powder molding apparatus having improved thickness uniformity of the powder molded body.

The second surface portion may be formed between the plurality of first surface portions.

According to this configuration, the density at both ends of the powder molded product can be increased, and the uniformity of thickness can be improved.

The difference in arithmetic mean roughness Ra of the plurality of first surface portions with respect to the second surface portion may be 0.2 or more and 1.2 or less.

According to this configuration, the uniformity of the thickness of the powder molded product can be further improved.

A convex portion protruding in the outer peripheral direction of the roll is formed on each of the plurality of first surface portions.
The height of the convex portions may be smaller than the predetermined interval.

According to this configuration, since the thin portion of the powder molded product can be cut by the convex portion, the uniformity of the thickness of the powder molded product can be improved.

The convex portion may have a shape in which the tip thereof becomes thinner toward the outer peripheral direction of the roll.

According to this configuration, the convex portion can cut a thin portion of the powder molded product and compact the cut portion, so that the strength of the powder molded product can be increased.

The convex portion has a first wall and a second wall that are inclined with respect to the surface of the roll.
The first wall is arranged on the center side of the roll.
The second wall is arranged on the end side of the roll.
The angle between the first wall and the surface of the roll may be 90 degrees or more and 150 degrees or less.

According to this configuration, the density of the cut portion due to the convex portion can be improved, and the strength of the powder molded product can be increased.

The plurality of rolls include a first roll and a second roll arranged to face the first roll.
The convex portion of the first roll and the convex portion of the second roll are arranged so as to face each other.
The gap between the convex portion of the first roll and the convex portion of the second roll may be 0% or more and 3% or less of the predetermined interval.

According to this configuration, the density of the cut portions at both ends of the powder molded body can be improved, so that the powder molded body having a uniform thickness can be molded. In addition, the strength of the powder molded product can be increased.

Hereinafter, embodiments will be described with reference to the drawings.

(Embodiment 1)
[overall structure]
FIG. 1 is a schematic view of the powder molding apparatus 100 of the present disclosure as viewed from above. FIG. 2 is a cross-sectional view taken along the line AA of the powder molding apparatus 100 of FIG. FIG. 3 is a schematic view of the pressure molding portion 16 of the powder molding apparatus 100 of FIG. 1 as viewed from the outlet direction of the powder molded body 13. FIG. 4 is a cross-sectional view taken along the line BB of the pressure forming portion 16 of the powder forming apparatus 100 of FIG. FIG. 5 is a cross-sectional view taken along the line CC of the pressure forming portion 16 of the powder forming apparatus 100 of FIG. FIG. 6 is an enlarged view of a part of FIG. In the following description, the X-axis direction in each figure may be referred to as a traveling direction, the Y-axis direction may be referred to as a width direction, and the Z-axis direction may be referred to as a vertical direction.

As shown in FIGS. 1 and 2, the powder forming apparatus 100 includes a material supply unit 15 and a pressure forming unit 16. The powder molding apparatus 100 supplies the powder material 101 indicated by the arrow 101 from the material supply unit 15 to the pressure molding unit 16 to continuously generate the powder molded body 13. The powder material 101 is, for example, a powdery material containing silicon oxide, metal, metal oxide or the like as a main component.

The material supply unit 15 has two screws 4a and 4b that convey the powder material in the direction of the rotation axis by being rotationally driven. The two screws 4a and 4b are arranged inside the housing 1 of the material supply unit 15 and are rotationally driven to convey the powder material 101 in the direction of the rotation axis. That is, the powder material 101 is conveyed in the traveling direction (X-axis direction) by the screws 4a and 4b.

In the present embodiment, two screws 4a and 4b are arranged, but the number of screws may be one. Preferably, a plurality of screws are arranged. The two motors 5a and 5b are arranged outside the housing 1 and rotationally drive the screws 4a and 4b, respectively.

The pressure forming unit 16 is arranged adjacent to the material supply unit 15. The pressure forming unit 16 has two rolls 12a and 12b arranged in parallel at predetermined intervals in the vertical direction (Z-axis direction).

The pressure molding unit 16 presses the powder material 101 supplied from the material supply unit 15 with the two rolls 12a and 12b to form the powder molded body 13. As shown in FIG. 2, the powder material is supplied from the discharge port 3 of the material supply unit 15 between the two rolls 12a and 12b of the pressure forming unit 16 and is pressurized by the rolls 12a and 12b. The sheet-shaped powder molded body 13 is molded.

<Screw>
As shown in FIG. 1, the screws 4a and 4b are arranged in parallel in the width direction inside the housing 1, and convey the powder material 101 in the material supply direction. The rotation axes of the screws 4a and 4b are parallel to the material supply direction, respectively. The screws 4a and 4b have screw shafts 42a and 42b, respectively, and flights 43a and 43b formed on the outer peripheral surfaces of the screw shafts 42a and 42b, respectively. The screws 4a and 4b are rotationally driven by the motors 5a and 5b. The rotation speeds of the motors 5a and 5b can be independently controlled by the control unit 6.

<Roll>
The rolls 12a and 12b are arranged in parallel at predetermined intervals. The predetermined distance means the distance h1 (see FIG. 6) between the roll 12a and the roll 12b in the nip portion 19 (see FIG. 4 or 5) where the distance between the roll 12a and the roll 12b is the smallest. The distance h1 between the roll 12a and the roll 12b in the nip portion 19 is, for example, preferably 2 mm or more and 10 mm or less. The rolls 12a and 12b are rotationally driven by the motor 14 shown in FIG. The rolls 12a and 12b have a rough surface portion 10 and a smooth surface portion 20 on the surface thereof. The rough surface portion 10 corresponds to the "first surface portion" of the present disclosure, and the sliding surface portion 20 corresponds to the "second surface portion" of the present disclosure. Further, the roll 12a corresponds to the "first roll" of the present disclosure, and the roll 12b corresponds to the "second roll" of the present disclosure.

<Rough surface>
As shown in FIG. 3, a plurality of rough surface portions 10 formed on the surfaces of the rolls 12a and 12b along the outer periphery of the rolls 12a and 12b, and a sliding surface portion 20 formed on a portion other than the plurality of rough surface portions 10 Have. The rough surface portions 10 are formed at portions located at both ends of the powder molded body 13 in the axial direction (width direction) of the rolls 12a and 12b. Further, in the present embodiment, on the surfaces of the rolls 12a and 12b, the sliding surface portion 20 is formed between the two rough surface portions 10. Both ends of the powder molded body 13 are both ends of the powder molded body 13 in the axial direction (width direction) of the rolls 12a and 12b. The rough surface portion 10 has a larger surface roughness than the smooth surface portion 20 other than the rough surface portion 10 on the surfaces of the rolls 12a and 12b.

The rough surface portion 10 may be formed on either one of the two rolls 12a and 12b. In the present embodiment, the rough surface portion 10 is provided on both of the two rolls 12a and 12b. Further, in the present embodiment, two rough surface portions 10 are formed on each of the rolls 12a and 12b, but one rough surface portion 10 may be formed on each of the rolls 12a and 12b.

The powder material 101 supplied to the pressure forming unit 16 by the material supply unit 15 is bitten between the rolls 12a and 12b by the rotation of the two rolls 12a and 12b of the pressure forming unit 16. It is conveyed in the material supply direction. At the portion where the powder material 101 and the rolls 12a and 12b first come into contact with each other, the powder material 101 slides with respect to the rotation of the rolls 12a and 12b. As the distance between the surface of the roll 12a and the surface of the roll 12b decreases, the frictional resistance between the powder material 101 and the surfaces of the rolls 12a and 12b increases, and the powder material 101 with respect to the rotation of the rolls 12a and 12b. It won't slip. When the powder material 101 does not slip with respect to the rotation of the rolls 12a and 12b, the powder material 101 is bitten between the rolls 12a and 12b and conveyed in the material supply direction.

The point at which the powder material 101 does not slip with respect to the rotation of the rolls 12a and 12b is called a biting point. FIG. 4 shows the biting point 17 on the sliding surface portion 20 of the rolls 12a and 12b, and FIG. 5 shows the biting point 18 on the rough surface portion 10 of the rolls 12a and 12b. Further, the portion where the distance between the roll 12a and the roll 12b is the smallest is referred to as a nip portion 19.

As shown in FIGS. 4 and 5, the biting point 18 on the rough surface portion 10 has a larger distance from the nip portion 19 than the biting point 17 on the sliding surface portion 20. This is because the rough surface portion 10 has a larger surface roughness than the smooth surface portion 20, and the powder material 101 is less likely to slip with respect to the rolls 12a and 12b. Therefore, the portion in contact with the rough surface portion 10 is bitten by the rolls 12a and 12b, and the amount of the powder material 101 to be compressed increases. Due to the friction of the material supply unit 15 with the housing 1, the flow velocity of the powder material 101 decreases at the end portion in the width direction. On the other hand, since the amount of the powder material 101 bitten into the rolls 12a and 12b increases at the portion of the end portion in the width direction that contacts the rough surface portion 10, the uniformity in the width direction of the molded powder molded body 13 is improved. can do.

In the material supply unit 15, the flow velocity at both ends in the width direction tends to decrease due to friction between the powder material 101 and the housing 1, so that the powder material 101 supplied to the pressure forming unit 16 is in the width direction. The density of the edges tends to be smaller. Pressurized by the rolls 12a and 12b due to the difference in the position of the biting point between the rough surface portion 10 and the sliding surface portion 20 and the difference in the density in the width direction of the powder material 101 supplied from the material supply portion 15. The uniformity of the thickness of the powder molded product 13 in the width direction is improved.

Therefore, if the rough surface portion 10 is provided on the surfaces of the rolls 12a and 12b, the uniformity of the thickness of the powder molded body 13 in the width direction can be improved.

<Convex part>
As shown in FIG. 3, the rough surface portion 10 is formed with a convex portion 11 protruding in the outer peripheral direction of the rolls 12a and 12b. The convex portion 11 is formed so that the height is smaller than the distance between the nip portions 19 of the rolls 12a and 12b. That is, the heights h2 and h3 of the convex portion 11 are smaller than the distance h1 between the roll 12a and the roll 12b in the nip portion 19 (see FIG. 6).

In the present embodiment, the convex portion 11 is formed in a shape in which the tip is tapered toward the outer peripheral direction of the rolls 12a and 12b, that is, in a tapered shape.

Further, in the present embodiment, as shown in FIG. 3, two convex portions 11 are formed on the rolls 12a and 12b, respectively. That is, the roll 12a (first roll) and the roll 12b (second roll) each have two rough surface portions 10 and two convex portions 11 arranged at both ends of the powder molded body 13. The two convex portions 11 of the roll 12a and the two convex portions 11 of the roll 12b are arranged so as to face each other.

In the present embodiment, the convex portion 11 is formed in a ring shape along the outer circumferences of the rolls 12a and 12b. For example, the convex portion 11 has a plurality of protrusions arranged along the outer circumferences of the rolls 12a and 12b. May be formed.

As shown in FIG. 4, the convex portion 11 has a first wall 11a and a second wall 11b that are inclined with respect to the surfaces of the rolls 12a and 12b. The first wall 11a is arranged on the center side of the rolls 12a and 12b. The second wall 11b is arranged on the end side of the rolls 12a and 12b.

The powder material 101 supplied from the material supply unit 15 to the pressure molding unit 16 is bitten between the rolls 12a and 12b and pressed to form the powder molded body 13. At this time, as shown in FIG. 6, the powder molded body 13 is cut along the convex portion 11.

Further, as shown in FIG. 6, the angle θ formed by the first wall 11a of the convex portion 11 and the surface of the roll 12a or the roll 12b is preferably 90 degrees or more and 150 degrees or less. By forming the convex portion 11 in this way, when the powder molded body 13 is cut by the convex portion 11, a load is applied from the convex portion 11 to the powder molded body 13 not only in the vertical direction but also in the width direction. Can be applied. The load in the thickness direction is a force for cutting the powder molded body 13, and the load in the width direction is a force for compacting the cut portion of the powder molded body 13. Therefore, the end portion of the powder molded body 13 cut by the convex portion 11 is less likely to collapse.

When the angle θ formed by the first wall 11a of the convex portion 11 and the surface of the roll is 90 degrees, 120 degrees, or 135 degrees, the end portion of the powder molded body 13 in the width direction is cut. The density of the portion 5 mm from the end portion (cut portion) in the width direction of the powder molded body 13 was measured. As a result, the density of the end portion of the powder molded body 13 in the width direction is 1.48 g / cc when the angle θ is 90 degrees, 1.51 g / cc when the size of the angle θ is 120 degrees, and the size of the angle θ is large. When the temperature was 135 degrees, it was 1.53 g / cc. The larger the angle θ, the larger the load in the width direction, so that the density of the end portion in the width direction of the powder molded body 13 becomes higher. On the other hand, in order to prevent the shape of the end portion of the powder molded body 13 in the width direction from being significantly separated from the rectangle due to the angle θ being too large, the size of the angle θ is 90 degrees or more and 150 degrees or less. Good. More preferably, the magnitude of the angle θ is 120 degrees or more and 135 degrees or less.

For example, when the convex portion is arranged so as to be fixed to the discharge port 3 of the material supply portion 15, frictional resistance occurs when the powder material 101 passes in the vicinity of the convex portion, and the powder molded product in the vicinity of the convex portion occurs. The density of the powder decreases. In the present embodiment, since the convex portion 11 is formed on the rolls 12a and 12b, the convex portion 11 rotates together with the rolls 12a and 12b. Therefore, the convex portion 11 can suppress obstruction of the flow of the powder material 101.

The convex portion 11 may be formed on either one of the two rolls 12a and 12b. When both the roll 12a and the roll 12b have the convex portion 11, as shown in FIG. 6, it is preferable that the convex portions are formed at overlapping positions in the vertical direction. In this case, the sum of the heights h2 and h3 of the convex portions 11 formed on the rolls 12a and 12b is larger than 97% of the distance h1 between the rolls 12a and the rolls 12b in the nip portion 19 and is 100% or less. Good. In other words, the gap between the two convex portions 11 of the roll 12a and the two convex portions 11 of the roll 12b facing the roll 12a is 0% or more and 3% or less of the distance h1 of the nip portion 19.

When either the roll 12a or the roll 12b has the convex portion 11, the height h2 or the height h3 of the convex portion 11 is 97% or more and 100% or less of the distance h1 between the roll 12a and the roll 12b in the nip portion 19. It is good to be. By forming the convex portion 11 at such a height, the convex portion 11 formed on the roll 12a and the convex portion 11 formed on the roll 12b interfere with each other, or the convex portion 11 and the roll 12a or the roll 12b Interference can be suppressed.

[Comparison by arrangement of rough surface]
With reference to FIG. 7, the arrangement of the rough surface portion 10 on the rolls 12a and 12b will be examined. FIG. 7 is a graph showing the density distribution in the width direction of the powder molded product 13 due to the difference in the arrangement of the rough surface portions 10 on the surfaces of the rolls 12a and 12b.

When the rough surface portion 10 is formed near the end portion in the width direction of the powder molded body 13 (Example 1), when the rough surface portion 10 is not formed (Comparative Example 1), and when the rough surface portion 10 is formed on the entire surface. (Comparative Example 2), the density distribution in the width direction of the powder molded product 13 was measured.

In the powder molding apparatus 100 used for the measurement, the width of the discharge port 3 of the material supply unit 15 is 100 mm. In the case of Comparative Example 1, rolls 12a and 12b in which the rough surface portion 10 was not formed (the entire surface was a smooth surface portion) were used. In the case of Example 1, rolls 12a and 12b having two rough surface portions 10 formed at positions 20 mm from both ends in the width direction of the powder molded body 13 were used. In the case of Comparative Example 2, the entire surface of the rolls 12a and 12b was designated as the rough surface portion 10.

In the graph of FIG. 7, the horizontal axis indicates the position in the width direction with the center in the width direction of the powder molded body 13 as 0, and the vertical axis indicates the density of the powder molded body 13 in the position in the width direction of the powder molded body 13. Is shown.

As shown in FIG. 7, in the case of Comparative Example 1, the density of the powder molded body 13 varies depending on the position in the width direction. Further, in the case of Comparative Example 2, the density of the powder molded body 13 near the center is higher than that near the end. On the other hand, in the case of Example 1, it can be seen that the variation in density depending on the position in the width direction is suppressed, and the uniformity of the density of the powder molded body 13 is improved in the width direction. Therefore, it can be seen that it is more effective to provide the rough surface portion 10 at the portion of the powder molded body 13 that contacts the end portion in the width direction.

In the measurements of Comparative Example 1, Comparative Example 2, and Example 1, the arithmetic mean roughness Ra of the rolls 12a and 12b was 0.2 for the smooth surface portion 20 and 0.4 for the rough surface portion 10. In Example 1 and Comparative Example 2, when the arithmetic mean roughness Ra of the rough surface portion 10 was set to 0.3, the density distribution in the width direction of the powder molded product 13 was about the same as in Comparative Example 2. Further, in Example 1 and Comparative Example 2, when the arithmetic mean roughness Ra of the rough surface portion 10 was set to 1.4, the density distribution was about the same as in the case of 0.4. Further, in Example 1 and Comparative Example 2, when the arithmetic average roughness Ra of the rough surface portion 10 is set to 1.6, the powder material 101 sticks to the rolls 12a and 12b, and the powder molded body 13 tears in the vertical direction. confirmed.

From the above, when the arithmetic average roughness Ra of the smooth surface portion 20 is 0.2, it is desirable that the arithmetic average roughness Ra of the rough surface portion 10 is 0.4 or more and 1.4 or less. That is, it is preferable that the difference in the arithmetic average roughness Ra of the rough surface portion 10 with respect to the smooth surface portion 20 is 0.2 or more and 1.2 or less. Further, it is preferable that the arithmetic average roughness Ra of the sliding surface portion 20 is less than 0.4.

Further, in the first embodiment, the width of the rough surface portion 10 is formed to be 20 mm so as to be in contact with both ends in the width direction of the powder molded body 13. For example, in the material supply unit 15, when the frictional resistance between the powder material 101 and the housing 1 is large, the width of the rough surface portion 10 may be further widened. On the contrary, when the frictional resistance between the powder material 101 and the housing 1 is small, the widths of the powder molded body 13 and the rough surface portion 10 may be further narrowed.

[effect]
According to the above-described embodiment, the rough surface portion 10 is provided on the surfaces of the rolls 12a and 12b to increase the frictional resistance of the portion where the flow velocity of the powder material 101 is slow, thereby improving the uniformity of the density of the powder molded body 13. can do. The uniformity of the thickness of the powder molded product can be improved.

The configuration and dimensions of the device shown in the present embodiment are examples, and are not limited to the present embodiment.

The powder molding apparatus of the present disclosure contributes to improving the performance of various industrial products that produce sintered bodies that are heat-treated at a temperature equal to or lower than the melting point of the powder after pressure molding the powder material. In particular, it is effective for improving the performance of insulating parts and battery materials.

4a screw 4b screw 10 rough surface part 11 convex part 11a first wall 11b second wall 12a roll 12b roll 13 powder molded body 15 material supply part 16 pressure molding part 100 powder molding device

Claims (7)

A powder molding device that continuously produces powder molded products.
A material supply unit having a screw that conveys powder material in the direction of the rotation axis by being rotationally driven,
A pressure molding unit having a plurality of rolls arranged in parallel at predetermined intervals and pressurizing the powder material supplied from the material supply unit by the plurality of rolls to form the powder molded body.
With
At least one of the plurality of rolls is formed on the surface of the roll at a portion located at both ends of the powder molded product in the axial direction of the roll along the outer circumference of the roll. It has one surface portion and a second surface portion formed on a portion other than the plurality of first surface portions.
The surface roughness of the plurality of first surface portions is larger than that of the second surface portion.
Powder molding equipment. The second surface portion is formed between the plurality of first surface portions.
The powder molding apparatus according to claim 1. The difference in arithmetic mean roughness Ra of the plurality of first surface portions with respect to the second surface portion is 0.2 or more and 1.2 or less.
The powder molding apparatus according to claim 1 or 2. A convex portion protruding in the outer peripheral direction of the roll is formed on each of the plurality of first surface portions.
The height of the convex portion is smaller than the predetermined interval.
The powder molding apparatus according to any one of claims 1 to 3. The convex portion has a shape in which the tip becomes thinner toward the outer peripheral direction of the roll.
The powder molding apparatus according to claim 4. The convex portion has a first wall and a second wall that are inclined with respect to the surface of the roll.
The first wall is arranged on the center side of the roll.
The second wall is arranged on the end side of the roll.
The angle between the first wall and the surface of the roll is 90 degrees or more and 150 degrees or less.
The powder molding apparatus according to claim 4 or 5. The plurality of rolls include a first roll and a second roll arranged to face the first roll.
The convex portion of the first roll and the convex portion of the second roll are arranged so as to face each other.
The gap between the convex portion of the first roll and the convex portion of the second roll is 0% or more and 3% or less of the predetermined interval.
The powder molding apparatus according to any one of claims 4 to 6.

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