Powder compact transport mechanism and powder compact molding device

Abstract

To make the conveyance of a green compact more smooth.SOLUTION: A green compact conveyance mechanism comprises: a conveyance passage 18 for a green compact 14 obtained by compression-molding powder 16 into a sheet shape; and an extrusion part feeding the green compact 14 to the downstream side of the conveyance passage 18 by extruding the green compact 14. The conveyance passage 18 has an exhaust port 28 for powder 16 fallen from the green compact 14 at a floor face 22.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a powder compact transport mechanism and a powder compact molding device. [Background technology]

[0002] Patent Document 1 discloses a powder sintering device in which raw material powder is passed through pressure rolls to form it into a plate, the formed green compact is transported by a conveyor to a heat compression unit, and the green compact is heated and pressurized in the heat compression unit to produce a sintered body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-157227 Summary of the Invention [Problem to be solved by the invention]

[0004] Conveyors, which are commonly used as transport mechanisms for articles, are complex in structure and relatively expensive because they themselves have a drive system. This can lead to the complexity and cost of the powder sintering device equipped with a conveyor. In contrast, if the pushing force of a roll is used to transport the green compact, the structure of the transport mechanism and, consequently, the device equipped with the transport mechanism can be simplified and the cost reduced.

[0005] The present inventors have conducted extensive research into mechanisms for transporting powder compacts that utilize a pushing force from the upstream side, and have come up with a technology for more smoothly transporting powder compacts.

[0006] The present disclosure has been made in view of the above circumstances, and its purpose is to provide a technique for more smoothly transporting a powder compact. [Means for solving the problem]

[0007] One aspect of the present disclosure is a powder compact transport mechanism. The mechanism includes a transport path for a powder compact formed by compressing powder into a sheet, and an extrusion unit that extrudes the powder compact to send the powder compact downstream along the transport path. The transport path has an outlet on its floor for discharging powder that has fallen off the powder compact.

[0008] Another aspect of the present disclosure is a powder compact molding apparatus, which includes an upstream press roll that compresses and molds powder into a sheet, and the powder compact transport mechanism of the above aspect, wherein the upstream press roll also serves as an extrusion section of the powder compact transport mechanism.

[0009] Any combination of the above components, and conversion of the expression of the present disclosure into a method, device, system, etc., are also valid aspects of the present disclosure. [Effects of the Invention]

[0010] According to the present disclosure, the powder compact can be transported more smoothly. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view schematically showing a powder compact molding apparatus according to an embodiment; [Figure 2] 2A and 2B are cross-sectional views of the conveying path taken along a plane BC and AB, respectively. [Figure 3] 3(A) to 3(C) are cross-sectional views showing other examples of the floor surface and the outlet. [Figure 4] Fig. 4(A) is a cross-sectional view of the upstream press roll, and Fig. 4(B) is an enlarged view of the area surrounded by the dashed line in Fig. 4(A). DETAILED DESCRIPTION OF THE INVENTION

[0012] The present disclosure will be described below with reference to preferred embodiments and drawings. The embodiments are illustrative and do not limit the present disclosure, and all features and combinations thereof described in the embodiments are not necessarily essential to the present disclosure. The same or equivalent components, parts, and processes shown in each drawing are designated by the same reference numerals, and redundant descriptions will be omitted where appropriate. The scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and should not be interpreted as limiting unless otherwise specified. Furthermore, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, these terms do not indicate any order or importance, but are intended to distinguish one configuration from another. Furthermore, some components that are not important for explaining the embodiments are omitted from each drawing.

[0013] 1 is a perspective view schematically illustrating a powder compact molding apparatus 1 according to an embodiment. The powder compact molding apparatus 1 includes a hopper 2, a feeder 4, an upstream press roll 6, a powder compact transport mechanism 8, a preheating furnace 10, and a downstream press roll 12.

[0014] The hopper 2 stores powder 16, which is the raw material for the powder compact 14. The powder 16 is, for example, a collection of particles having a particle diameter of less than 100 μm, and the particle diameter distribution is not particularly limited. The powder 16 is supplied from the hopper 2 to the feeder 4. The feeder 4 can be configured as a known screw feeder or the like. The feeder 4 supplies the powder 16 to the upstream press roll 6.

[0015] The upstream press roll 6 in this embodiment is composed of a pair of rolls (a concave roll 30 and a convex roll 32, which will be described later) arranged with a predetermined gap between them. The configuration of the upstream press roll 6 will be described in detail later. As the powder 16 passes between the pair of rotating rolls, the powder 16 is compression-molded into a sheet. This results in a sheet-like green compact 14. The green compact 14 is continuously sent out from the upstream press roll 6 to the conveying path 18. Therefore, the green compact 14 has a long strip shape in the conveying direction A.

[0016] The conveying path 18 extends in the conveying direction A of the powder compact 14 and guides the progress of the powder compact 14. As an example, the conveying path 18 extends horizontally. The shape of the conveying path 18 will be described in detail later. The conveying path 18 constitutes a powder compact conveying mechanism 8. In addition to the conveying path 18, the powder compact conveying mechanism 8 also includes an extrusion unit 20. The extrusion unit 20 extrudes the powder compact 14 in the conveying direction A, thereby sending the powder compact 14 downstream of the conveying path 18. In this embodiment, the upstream press roll 6 also serves as the extrusion unit 20 of the powder compact conveying mechanism 8. It should be noted that the extrusion unit 20 may be provided separately from the upstream press roll 6.

[0017] The powder compact 14 reaches the preheating furnace 10 via a conveying path 18. The preheating furnace 10 heats the powder compact 14 to a predetermined temperature, for example, between 400°C and 800°C, before the powder compact 14 is heated and compressed by the downstream press roll 12. The preheating furnace 10 can be configured with a known heater or the like. The powder compact 14 heated in the preheating furnace 10 is supplied to the downstream press roll 12. As an example, the downstream press roll 12 is configured with a pair of rolls arranged at a predetermined distance. Each roll has a built-in heater, and its surface is heated to a predetermined temperature, for example, between 400°C and 800°C. The powder compact 14 is heated and pressurized as it passes between the pair of rolls, becoming a sintered body.

[0018] The configuration of the powder compact molding apparatus 1 is not limited to the above and can be modified as appropriate. For example, the upstream press roll 6 may be a hot press roll having a heater. The conveying path 18 may be a heated conveying path having a heater. In this case, the heater may also serve as the preheating furnace 10. The downstream press roll 12 may be a room-temperature press roll without a heater. The downstream press roll 12 may also be a stretching roll that stretches the powder compact 14.

[0019] Next, the structure of the conveying path 18 will be described. FIG. 2(A) is a cross-sectional view of the conveying path 18 taken along the BC plane. FIG. 2(B) is a cross-sectional view of the conveying path 18 taken along the AB plane. The BC plane extends in the width direction B and the thickness direction C, and the AB plane extends in the conveying direction A and the width direction B. The conveying path 18 of this embodiment is tunnel-shaped and has a floor surface 22, a pair of side surfaces 24, and a ceiling surface 26. The powder compact 14 slides on the floor surface 22 in the conveying direction A. The pair of side surfaces 24 are aligned in the width direction B of the powder compact 14, which intersects with the conveying direction A. The ceiling surface 26 faces the floor surface 22 in the thickness direction C of the powder compact 14, which intersects with the conveying direction A and the width direction B. The floor surface 22, the pair of side surfaces 24, and the ceiling surface 26 surround the periphery of the powder compact 14.

[0020] The distance between the pair of side surfaces 24 is set slightly larger than the dimension of the powder compact 14 in the width direction B so as not to hinder the progress of the powder compact 14 within the passage. For example, the size of the powder 16 in the width direction B is about 100 mm, and the distance between the pair of side surfaces 24 is about 110 mm. In addition, the distance between the floor surface 22 and the ceiling surface 26 is set slightly larger than the dimension of the powder compact 14 in the thickness direction C.

[0021] The width of the conveying path 18 is greater than the width of the powder compact 14. The powder compact 14 may deviate in the width direction B while traveling through the conveying path 18 and collide with the side surface 24. When the powder compact 14 collides with the side surface 24, powder 16 may fall off from the powder compact 14. Powder 16 may also fall off from the contact point between the floor surface 22 and the powder compact 14. There may also be powder 16 that is not sufficiently pressed onto the powder compact 14. Such powder 16 may also fall off due to vibrations or the like that accompany the conveying of the powder compact 14. If powder 16 falls off from the powder compact 14 and accumulates, the conveying path 18 may become clogged, and the conveying of the powder compact 14 may be impeded.

[0022] In contrast, the transport path 18 of this embodiment has a discharge port 28 on the floor surface 22. The discharge port 28 connects the inside and outside of the transport path 18. The discharge port 28 also extends continuously in the transport direction A. The powder 16 that has fallen off the powder compact 14 is discharged to the outside of the transport path 18 through the discharge port 28. This makes it possible to prevent clogging of the transport path 18.

[0023] Furthermore, the floor surface 22 in this embodiment is inclined from both ends in the width direction B toward the center so as to move away from the powder compact 14. As an example, the floor surface 22 has a substantially V-shape in cross section along the BC plane. In other words, the inclined surface is linear. By providing such an inclination to the floor surface 22, the position through which the powder compact 14 passes can be brought closer to the center of the conveying path 18. This can prevent collisions between the powder compact 14 and the side surfaces 24 and prevent the powder 16 from falling off.

[0024] Furthermore, the discharge outlet 28 is disposed at the center of the floor surface 22 in the width direction B. In other words, the discharge outlet 28 is disposed at the apex of the V-shape. Even if the floor surface 22 is V-shaped to prevent collision between the powder compact 14 and the side surface 24, the powder 16 may fall off from the powder compact 14 due to contact with the floor surface 22, as described above. The fallen powder 16 collects in the center due to the inclination of the floor surface 22. Therefore, by locating the discharge outlet 28 in the center of the floor surface 22, the fallen powder 16 can be efficiently discharged.

[0025] The shape of the floor surface 22 and the number, arrangement, and shape of the discharge ports 28 are not limited to those described above and can be modified as appropriate. FIGS. 3A to 3C are cross-sectional views showing other examples of the floor surface 22 and the discharge ports 28. For example, the floor surface 22 may be substantially U-shaped in cross section along the plane B-C, as shown in FIG. 3A. That is, the inclined surface may be curved. Furthermore, for example, the conveying path 18 may have multiple discharge ports 28, as shown in FIG. 3B. The multiple discharge ports 28 are arranged so as to be offset from one another in the width direction B. Furthermore, for example, the discharge ports 28 may be provided intermittently in the conveying direction A, as shown in FIG. 3C. The opening shape of the discharge ports 28 may be rectangular or circular.

[0026] The above-described modifications can also be combined as appropriate. For example, all or some of the multiple discharge ports 28 aligned in the width direction B may be provided intermittently in the conveying direction A. Furthermore, the discharge ports 28 may be provided intermittently in the conveying direction A on the U-shaped floor surface 22. Furthermore, the U-shaped floor surface 22 may be provided with multiple discharge ports 28 offset in the width direction B. These multiple discharge ports 28 may be continuous or intermittent in the conveying direction A. Furthermore, the discharge ports 28 may be provided on a floor surface 22 that does not have an inclined surface. In this case, it is preferable to provide the discharge ports 28 directly below the side surfaces 24. This allows the powder 16 that has fallen off the powder compact 14 due to collision with the side surfaces 24 to fall directly into the discharge ports 28.

[0027] Next, the structure of the upstream press roll 6 will be described. Fig. 4(A) is a cross-sectional view of the upstream press roll 6. Fig. 4(B) is an enlarged view of the area surrounded by the dashed line in Fig. 4(A). The upstream press roll 6 of this embodiment has a concave roll 30 and a convex roll 32. The concave roll 30 has recesses 34 on its circumferential surface. The recesses 34 extend around the entire circumference of the concave roll 30. The convex roll 32 is disposed so that its circumferential surface faces the circumferential surface of the concave roll 30. In addition, the convex roll 32 has convex portions 36 on its circumferential surface. The convex portions 36 extend around the entire circumference of the convex roll 32.

[0028] The convex portions 36 mesh with the concave portions 34. With the concave portions 34 and the convex portions 36 meshed, the bottom surfaces 34a of the concave portions 34 and the top surfaces 36a of the convex portions 36 extend parallel to each other. A gap corresponding to the thickness of the powder compact 14 is formed between the bottom surfaces 34a and the top surfaces 36a. With the concave roll 30 and the convex roll 32 rotating in opposite directions, the feeder 4 supplies powder 16 between the concave portions 34 and the convex portions 36. The powder 16 is then compressed by the concave portions 34 and the convex portions 36 to form the powder compact 14. The powder compact 14 is sent to the conveying path 18 by the extrusion force generated by the rotation of the concave roll 30 and the convex roll 32.

[0029] With the recesses 34 and the protrusions 36 interlocked, the side surfaces 34b of the recesses 34 facing inward in the width direction B and the side surfaces 36b of the protrusions 36 facing outward in the width direction B face each other. With the side surfaces 34b and 36b facing each other, the space formed between the bottom surface 34a and the top surface 36a is substantially closed at both ends in the width direction B. Therefore, if the powder 16 were compressed using two rolls that do not have the recesses 34 and the protrusions 36, the pressure applied to the powder 16 at both ends in the width direction B would decrease. However, by compressing the powder 16 using the recesses 34 and the protrusions 36, this decrease in pressure can be suppressed. This makes it possible to suppress a decrease in the density and rigidity of the compact 14 at both ends.

[0030] On the other hand, when the concave roll 30 and the convex roll 32 are used, the powder 16 may enter the gap between the side surfaces 34b of the concave portions 34 and the side surfaces 36b of the convex portions 36, causing burrs to form on the ends of the powder compact 14. If burrs form, they may stick to the side surfaces 36b of the convex portions 36 or the side surfaces 34b of the concave portions 34, which may hinder the powder compact 14 from being sent out to the conveying path 18.

[0031] In contrast, in the upstream press roll 6 of this embodiment, the ends 34c of the recesses 34 in the width direction B and the ends 36c of the protrusions 36 in the width direction B are offset in the width direction B by more than 0.4 mm but less than 1.0 mm. The ends 34c are the portions where the bottom surface 34a and the side surfaces 34b meet. The bottom surface 34a extends parallel to the width direction B, and the side surfaces 34b extend from the ends of the bottom surface 34a in a direction intersecting with the width direction B. Therefore, the ridge line between the bottom surface 34a and the side surfaces 34b corresponds to the ends 34c. Similarly, the ends 36c are the portions where the top surface 36a and the side surfaces 36b meet. The top surface 36a extends parallel to the width direction B, and the side surfaces 36b extend from the ends of the top surface 36a in a direction intersecting with the width direction B. Therefore, the ridge line between the top surface 36a and the side surfaces 36b corresponds to the ends 36c.

[0032] By offsetting the ends 34c and 36c in the width direction B by more than 0.4 mm, a gap G of at least 0.4 mm can be formed between the side surfaces 34b and 36b. By forming the gap G, the pressure applied to the powder 16 at the ends in the width direction B can be appropriately reduced. This reduces the rigidity of the burrs, making them more fragile, and thus the powder compact 14 is more likely to peel off from the convex roll 32 and the concave roll 30. This reduces the risk of impeding the delivery of the powder compact 14 to the conveying path 18. Furthermore, by offsetting the ends 34c and 36c in the width direction B by less than 1.0 mm, an excessive reduction in the pressure applied to the powder 16 at both ends in the width direction B can be prevented. This allows the density and rigidity of both ends of the powder compact 14 to be maintained.

[0033] As described above, the powder compact transport mechanism 8 according to this embodiment includes the transport path 18 for the powder compact 14, which is obtained by compressing and molding powder 16 into a sheet shape, and the extrusion unit 20 that extrudes the powder compact 14 to send the powder compact 14 downstream along the transport path 18. The transport path 18 has an outlet 28 in its floor surface 22 for the powder 16 that has fallen off the powder compact 14. By providing the outlet 28 in the transport path 18 in this way, the powder 16 that has fallen off the powder compact 14 within the transport path 18 can be discharged outside the transport path 18. This makes it possible to transport the powder compact 14 more smoothly.

[0034] Furthermore, since it is possible to prevent the transfer path 18 from being clogged and the transfer of the powder compact 14 from being stagnated, it is possible to improve the availability of the powder compact transfer mechanism 8. As a result, it is possible to improve the throughput of the powder compact molding device 1 equipped with the powder compact transfer mechanism 8. Furthermore, since the powder compact 14 is transferred by the extrusion unit 20, it is possible to simplify the structure of the powder compact transfer mechanism 8 compared to when a conveyor, which is a common transfer means, is used.

[0035] Furthermore, the floor surface 22 of this embodiment is inclined from both ends of the powder compact 14 toward the center in the width direction B so as to move away from the powder compact 14. This improves the linearity of the powder compact 14 and suppresses the powder 16 from falling off the powder compact 14. This allows for smoother transport of the powder compact 14. Furthermore, the discharge port 28 is located in the center in the width direction B of the floor surface 22. This allows the powder 16 that has fallen off the powder compact 14 to be collected in the center in the width direction B by utilizing the inclination of the floor surface 22 and discharged from the discharge port 28. This allows for smoother transport of the powder compact 14. Furthermore, the transport path 18 may have multiple discharge ports 28 that are positioned offset from each other in the width direction B. This increases the discharge rate of the powder 16 and allows for smoother transport of the powder compact 14.

[0036] The powder compact molding apparatus 1 of this embodiment also includes an upstream press roll 6 that compresses and molds the powder 16 into a sheet, and a powder compact transport mechanism 8. The upstream press roll 6 also serves as the extrusion section 20 of the powder compact transport mechanism 8. This allows the structure of the powder compact molding apparatus 1 to be simplified.

[0037] Furthermore, the upstream press roll 6 of this embodiment has a concave roll 30 having recesses 34 on its circumferential surface, and a convex roll 32 that faces the concave roll 30 and has protrusions 36 on its circumferential surface that mesh with the recesses 34. The upstream press roll 6 compresses the powder 16 using the recesses 34 and the protrusions 36 to form the powder compact 14. This makes it possible to obtain a powder compact 14 with a more uniform density in the width direction B. Furthermore, the rigidity of both ends of the powder compact 14 can be maintained, making it possible to prevent the powder 16 from falling off. This makes it possible to more smoothly transport the powder compact 14.

[0038] Furthermore, in the upstream press roll 6 of this embodiment, the ends 34c of the recesses 34 in the width direction B are offset from the ends 36c of the protrusions 36 in the width direction B by more than 0.4 mm and less than 1.0 mm in the width direction B. This makes it possible to maintain the density and rigidity of both ends of the powder compact 14 while suppressing transport problems of the powder compact 14 caused by burrs.

[0039] The embodiments of the present disclosure have been described in detail above. The above-described embodiments merely illustrate specific examples of implementing the present disclosure. The content of the embodiments does not limit the technical scope of the present disclosure, and many design modifications, such as changing, adding, or deleting components, are possible within the scope of the concept of the present disclosure defined in the claims. A new embodiment with design modifications will combine the effects of the combined embodiments and modifications. In the above-described embodiments, the content that allows such design modifications is emphasized by using notations such as "in this embodiment" or "in this embodiment," but design modifications are also permitted even in content without such notation. Any combination of the components included in each embodiment is also valid as an aspect of the present disclosure. Hatching on cross sections in the drawings does not limit the material of the hatched object.

[0040] The embodiments may be specified by the following items. [Item 1] a conveying path (18) for a compact (14) formed by compressing powder (16) into a sheet shape; an extrusion section (20) that extrudes the powder compact (14) to send the powder compact (14) downstream of the conveyance path (18); The conveying path (18) has a discharge port (28) on the floor surface (22) for the powder (16) that has fallen off the powder compact (14). Compacted powder transport mechanism (8). [Item 2] The floor surface (22) is inclined from both ends toward the center in a width direction (B) of the powder compact (14) intersecting with the conveying direction (A) of the powder compact (14) so ​​as to move away from the powder compact (14). Item 1. The powder compact transport mechanism (8). [Item 3] The discharge port (28) is disposed at the center of the floor surface (22) in the width direction (B). Item 2. The powder compact transport mechanism (8). [Item 4] The conveying path (18) has a plurality of discharge ports (28), The plurality of discharge openings (28) are arranged so as to be shifted in a width direction (B) of the powder compact (14) that intersects with a conveying direction (A) of the powder compact (14). 4. A powder compact transport mechanism (8) according to any one of items 1 to 3. [Item 5] an upstream press roll (6) that compresses and molds the powder (16) into a sheet; The powder compact transport mechanism (8) according to any one of items 1 to 4, The upstream press roll (6) also serves as the extrusion section (20) of the powder compact transport mechanism (8). Powder compaction device (1). [Item 6] The upstream press roll (6) has a concave roll (30) having concave portions (34) on its circumferential surface, and a convex roll (32) that faces the concave roll (30) and has convex portions (36) on its circumferential surface that mesh with the concave portions (34), and the powder (16) is compressed by the concave portions (34) and the convex portions (36) to form a powder compact (14). Item 6. The powder compact molding apparatus (1) according to item 5. [Item 7] In the upstream press roll (6), an end (34 c) of the recess (34) in a width direction (B) of the powder compact (14) intersecting with the conveying direction (A) of the powder compact (14) is offset from an end (36 c) of the protrusion (36) in the width direction (B) by more than 0.4 mm but less than 1.0 mm in the width direction. Item 7. The powder compact molding apparatus (1) according to item 6. [Explanation of symbols]

[0041] 1 powder compact molding device, 6 upstream press roll, 8 powder compact transport mechanism, 14 powder compact, 16 powder, 18 transport path, 20 extrusion section, 22 floor surface, 28 discharge outlet, 30 concave roll, 32 convex roll, 34 concave portion, 34c end, 36 convex portion, 36c end.

Claims

1. a conveyance path for a powder compact formed by compressing powder into a sheet shape, the conveyance path being a tunnel-like path defined by a floor surface, a pair of side surfaces aligned in a width direction of the powder compact intersecting with a conveyance direction of the powder compact, and a ceiling surface facing the floor surface in a thickness direction of the powder compact intersecting with the conveyance direction and the width direction; an extrusion unit that extrudes the powder compact to send the powder compact to a downstream side of the conveying path, the conveying path has a discharge port on the floor surface for discharging powder that has fallen off the powder compact; Compacted powder transport mechanism.

2. the floor surface is inclined from both end portions toward the center portion in the width direction so as to move away from the powder compact; The powder compact transport mechanism according to claim 1 .

3. The discharge port is disposed at a center portion of the floor surface in the width direction. The powder compact transport mechanism according to claim 2 .

4. the transport path has a plurality of the discharge ports, The plurality of discharge ports are arranged to be shifted in the width direction. The powder compact transport mechanism according to any one of claims 1 to 3.

5. the powder compact slides on the floor surface in the conveying direction; a distance between the pair of side surfaces in the width direction is set to be larger than a dimension of the powder compact in the width direction; The powder compact transport mechanism according to any one of claims 1 to 4.

6. an upstream press roll that compresses and molds the powder into a sheet; and the powder compact transport mechanism according to any one of claims 1 to 5, The upstream press roll also serves as the extrusion section of the powder compact transport mechanism. Powder compaction equipment.

7. the upstream press roll has a concave roll having concave portions on its circumferential surface, and a convex roll facing the concave roll and having convex portions on its circumferential surface that engage with the concave portions, and the powder is compressed by the concave portions and the convex portions to form the green compact; The powder compact molding apparatus according to claim 6.

8. the upstream press roll has an end of the recess in the width direction and an end of the protrusion in the width direction offset by more than 0.4 mm and less than 1.0 mm in the width direction; The powder compact molding apparatus according to claim 7.

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