Mixing device, and method for producing mixture

Abstract

A mixing device according to one aspect of the present disclosure comprises: a conveyance unit that conveys a powder; a powder molding mechanism that molds the powder into a layered shape; and a liquid spraying mechanism that sprays a liquid onto the powder molded into a layered shape. The powder molding mechanism comprises a first blade and a second blade that mold the powder in a height direction in relation to the conveyance unit, and the height of the blades in relation to the conveyance unit varies during conveyance of the powder by the conveyance unit.

Description

Mixing device and method for producing a mixture

[0001] The present disclosure relates to a mixing device for mixing powder and liquid, and a method for producing a mixture using the mixing device.

[0002] Patent Document 1 discloses an apparatus for manufacturing a clad brazing sheet, which includes rolling rollers for rolling a metal plate and raw material powder having a brazing composition. The apparatus includes a liquid supply device for supplying a liquid to the raw material powder being rolled by the rolling rollers to adjust the adhesive force between particles constituting the raw material powder. The liquid supply device has a spray nozzle for supplying a liquid to the raw material powder being transported by a belt feeder.

[0003] Japanese Patent Publication No. 2009-95871

[0004] A mixing device according to one aspect of the present disclosure comprises a conveying section that conveys powder, a powder forming mechanism that forms the powder into layers, and a liquid spraying mechanism that sprays liquid onto the powder that has been formed into layers, wherein the powder forming mechanism comprises a blade that forms the powder in a height direction relative to the conveying section, and the height of the blade relative to the conveying section varies continuously while the powder is being conveyed by the conveying section.

[0005] Furthermore, a method for producing a mixture according to one aspect of the present disclosure includes a conveying unit that conveys powder, a powder forming mechanism that forms the powder into layers, and a liquid spraying mechanism that sprays liquid onto the powder that has been formed into layers, wherein the powder forming mechanism includes one or more blades that form the powder in a height direction relative to the conveying unit, and the height of the blades relative to the conveying unit fluctuates between a first height and a second height higher than the first height while the powder is being conveyed by the conveying unit, and the method includes a conveying step that conveys the powder by the conveying unit, a powder forming step that forms the powder being conveyed in the conveying step into layers by the powder forming mechanism, and a liquid spraying step that sprays liquid onto the powder that has been formed into layers in the powder forming step by the liquid spraying mechanism.

[0006] 2 is a perspective view showing the configuration of the mixing device according to embodiment 1. FIG. 3 is a plan view showing the configuration of the mixing device according to embodiment 1. FIG. 4 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 5 is a cross-sectional view taken along line IV-IV in FIG. 2. FIG. 6 is a flow chart showing an example of a method for producing a mixture using the mixing device according to embodiment 1, which is a side view of a cover provided in the liquid spraying mechanism. FIG. 7 is a perspective view showing the configuration of the mixing device according to embodiment 2. FIG. 8 is a cross-sectional view showing the configuration of a powder molding mechanism provided in the mixing device according to embodiment 2. FIG. 9 is a plan view showing a movement mechanism provided in the mixing device according to embodiment 2 and the configuration of its periphery.

[0007] [Embodiment 1] One embodiment of the present disclosure will be described in detail below. In the following description, "A to B" indicating a numerical range means "A or more, B or less" unless otherwise specified.

[0008] Fig. 1 is a perspective view showing the configuration of a mixing device 1 according to embodiment 1. Fig. 2 is a top view showing the configuration of the mixing device 1. As shown in Figs. 1 and 2, the mixing device 1 may include a conveying unit 10, a powder molding mechanism 20, a liquid spraying mechanism 30, a moving mechanism 40, a control unit 50, and a memory unit 60. The control unit 50 and the memory unit 60 are omitted in Fig. 2.

[0009] The conveying unit 10 may be configured to be able to convey powder 90. For simplicity, the powder 90 is omitted from Fig. 1. The powder 90 is, for example, ceramic particles. Specific examples of the powder 90 include alumina powder, zirconia powder, and graphite powder.

[0010] The conveying unit 10 may include a first conveying unit 11 and a second conveying unit 12. The first conveying unit 11 and the second conveying unit 12 may be, for example, belt conveyors including a circular belt and pulleys for rotating the belt. The conveying direction of the powder 90 by the first conveying unit 11 and the conveying direction of the powder 90 by the second conveying unit 12 may be the same or different from each other. In particular, when the conveying direction of the powder 90 by the first conveying unit 11 and the conveying direction of the powder 90 by the second conveying unit 12 are the same, when the powder 90 moves from the first conveying unit 11 to the second conveying unit 12, variation in the thickness of the powder 90 in the direction along the conveying surface along which the conveying unit 10 conveys the powder 90 and in the direction perpendicular to the conveying direction can be reduced.

[0011] In the following description, the conveying direction of the powder 90 by the first conveying unit 11 and the conveying direction of the powder 90 by the second conveying unit 12 may be referred to as the conveying direction of the powder 90 by the conveying unit 10 or simply as the conveying direction. Furthermore, the direction along the conveying surface along which the conveying unit 10 conveys the powder 90 and which is perpendicular to the conveying direction may be referred to as the width direction.

[0012] The first conveying unit 11 has an upstream end 11a and a downstream end 11b in the conveying direction, and a conveying surface 11c that conveys the powder 90 between the upstream end 11a and the downstream end 11b. A powder forming mechanism 20 is located on the conveying surface 11c. The second conveying unit 12 has an upstream end 12a and a downstream end 12b in the conveying direction, and a conveying surface 12c that conveys the powder 90 between the upstream end 12a and the downstream end 12b. A liquid spraying mechanism 30 and a moving mechanism 40 are located on the conveying surface 12c, in this order, in the conveying direction. A region of the second conveying unit 12 between the upstream end 12a and the liquid spraying mechanism 30 is located below the downstream end 11b of the first conveying unit 11.

[0013] In the mixing device 1, powder 90 is supplied into a powder shaping mechanism 20 located in the first conveying section 11. The powder 90 is shaped by the powder shaping mechanism 20 and conveyed from the powder shaping mechanism 20 to the downstream end 11b of the first conveying section 11. The powder 90 falls from the downstream end 11b of the first conveying section 11. The second conveying section 12 conveys the powder that has fallen from the first conveying section 11. During the process of being conveyed by the second conveying section 12, liquid is sprayed onto the powder 90 by a liquid spraying mechanism 30.

[0014] In the mixing device 1, by dropping the powder 90 from the first conveying section 11 to the second conveying section 12, it is possible to reduce unevenness formed on the surface of the powder 90 during the molding process by the powder molding mechanism 20. Therefore, it is possible to reduce variation in the ratio of the powder 90 to the liquid sprayed by the liquid spraying mechanism 30, which is caused by the unevenness formed on the surface of the powder 90.

[0015] The mixing device 1 may include a first scraping plate 13 for scraping the powder 90 from the first conveying section 11. The first scraping plate 13 may be located at the downstream end 11b of the first conveying section 11. The first scraping plate 13 can scrape the powder 90 adhering to the first conveying section 11 and drop it into the second conveying section 12.

[0016] The mixing device 1 may also include a second scraping plate 14 for scraping the powder 90 from the second conveying section 12. The second scraping plate 14 may be located at the downstream end 12b of the second conveying section 12. The second scraping plate 14 can scrape the powder 90 adhering to the second conveying section 12 and allow it to fall from the downstream end 12b of the second conveying section 12. A container (not shown) for collecting the mixture may be provided below the downstream end 12b. The materials of the first scraping plate 13 and the second scraping plate 14 are not particularly limited as long as they can scrape the powder 90 from the conveying section 10, but metal materials such as stainless steel can be used. The materials of the first scraping plate 13 and the second scraping plate 14 may be the same or different.

[0017] In the first conveying section 11, the material of the conveying surface 11c may be rubber. This reduces slippage of the powder 90 on the conveying surface 11c. Therefore, as will be described later, it becomes easier to form the powder 90 using the powder forming mechanism 20. Furthermore, in the second conveying section 12, the material of the conveying surface 12c may be stainless steel. This reduces deterioration of the conveying surface 12c due to the liquid sprayed from the liquid spraying mechanism 30, which will be described later. However, the materials of the conveying surfaces 11c and 12c are not limited to the above examples. For example, both the conveying surfaces 11c and 12c may be made of rubber or stainless steel.

[0018] The first conveying speed of the powder 90 by the first conveying unit 11 and the second conveying speed of the powder 90 by the second conveying unit 12 need to be adjusted appropriately depending on the material of the powder 90, but may be, for example, 10 mm / s to 80 mm / s. If the conveying speed is less than 10 mm / s, the throughput per unit time decreases, thereby reducing the productivity of the mixture produced by the mixer 1. Furthermore, if the conveying speed is faster than 80 mm / s, it becomes difficult to control the liquid spraying mechanism 30 (described later) to spray the liquid uniformly over the layered powder 90.

[0019] Furthermore, the first conveying speed and the second conveying speed may be different from each other. In this case, the thickness of the powder 90 in the second conveying section 12 can be adjusted by adjusting the difference between the first conveying speed and the second conveying speed. For example, when the second conveying speed is faster than the first conveying speed, the thickness of the powder 90 in the second conveying section 12 is thinner than the thickness of the powder 90 in the first conveying section 11. When the second conveying speed is slower than the first conveying speed, the thickness of the powder 90 in the second conveying section 12 is thicker than the thickness of the powder 90 in the first conveying section 11.

[0020] The powder forming mechanism 20 may be configured to be able to form the powder 90 into a layer. As described above, the powder forming mechanism 20 may be located on the first conveying unit 11. The powder forming mechanism 20 may include a first blade 21, a second blade 22, a first side wall 23, a second side wall 24, and a rear wall 25.

[0021] The first blade 21 and the second blade 22 may be configured to be able to mold the powder 90 in the height direction relative to the conveying section 10. However, the number of blades included in the powder molding mechanism 20 may be one, or may be three or more. In the following description, the first blade 21 and the second blade 22 may be collectively referred to simply as blades.

[0022] The blade may have a plate-like shape extending along the width direction of the conveying unit 10. The thickness of the blade in the conveying direction near the lower end thereof becomes thinner as it goes downward. The material of the blade is not particularly limited as long as it can mold the powder 90, but for example, a metal material such as stainless steel can be used.

[0023] Alternatively, the blade may have a flat plate shape with a constant thickness. In this case, the blade thickness may be 0.1 mm to 0.5 mm. If the blade thickness is less than 0.1 mm, the blade descending toward the powder 90 is likely to be pushed by the powder 90 and deformed. If the blade thickness is greater than 0.5 mm, the powder 90 pushed by the blade is likely to be compressed under the blade without spreading out in front of and behind the blade. In this case, the compressed powder 90 is unlikely to be impregnated with liquid.

[0024] Figure 3 is a cross-sectional view taken along line III-III in Figure 2. The configuration of the powder molding mechanism 20 is shown in Figure 3. Also shown in Figure 3 is a powder supply mechanism 29. The powder supply mechanism 29 supplies powder 90 to an area surrounded by the first side wall 23, the second side wall 24, the rear wall 25, and the first blade 21. The powder supply mechanism 29 may be a part of the mixing device 1, or may be a device separate from the mixing device 1.

[0025] The heights of the first blade 21 and the second blade 22 vary between a first height and a second height higher than the first height while the conveying unit 10 is conveying the powder 90. That is, the first blade 21 and the second blade 22 may be configured to be able to move (vibrate) up and down. The mixer 1 may include a drive mechanism (not shown) for varying the heights of the first blade 21 and the second blade 22.

[0026] The blade may move up and down continuously or intermittently, but in the following description, it is assumed that the blade moves up and down continuously.

[0027] The first height of the blade is the lower limit of the thickness of the powder 90 formed by the blade. The second height of the blade is the upper limit of the thickness of the powder 90 formed by the blade. The surface of the powder formed by the blade has a wavy shape in the conveyance direction between the first height and the second height of the blade.

[0028] The first blade 21 molds the powder 90 into a first molded body 91 so that the thickness of the powder 90 is between the first height and the second height of the first blade 21. The first molded body 91 is made of the same material as the powder 90. The second blade 22 molds the first molded body 91 into a second molded body 92 so that the thickness of the powder 90 is between the first height and the second height of the second blade 22. The second molded body 92 is made of the same material as the powder 90 and the first molded body 91.

[0029] When the blade height is constant at the first height, the first molded body 91 is transported with its upper surface in contact with the side surface of the first blade 21. The second molded body 92 is transported with its upper surface in contact with the side surface of the second blade 22. In this case, the transport of the first molded body 91 and the second molded body 92 may be disrupted. By moving the blade up and down, this disruption can be reduced, allowing the powder 90 to be transported smoothly.

[0030] Furthermore, the powder 90 may contain clumps that are larger than the first height of the blade and can be crushed by the blade. The blade crushes such clumps during the molding of the powder 90. However, if the powder 90 is slippery on the conveying surface 11c, the clumps of the powder 90 may slip in front of the blade, causing streaks in the molded body downstream of the clumps.

[0031] As described above, if the material of the conveying surface 11c is rubber, it is possible to reduce the slippage of the powder 90 on the conveying surface 11c. Therefore, clumps of the powder 90 can be broken up by the blade, and the powder 90 can be formed into layers.

[0032] The first height of the blade located downstream in the conveying direction may be lower than the first height of the blade located upstream in the conveying direction. In the example shown in Figures 1 and 2, the first height of the second blade 22 may be lower than the first height of the first blade 21. By gradually changing the thickness of the powder 90 using multiple blades, the powder 90 can be spread uniformly in stages in the width direction and can be formed to a constant thickness.

[0033] The thickness of the powder 90 formed by the second blade 22 is the final thickness of the powder 90 formed by the powder forming mechanism 20. The first height of the second blade 22 may be, for example, 4 mm or less. If the first height of the second blade 22 is greater than 4 mm, the liquid sprayed by the liquid spraying mechanism 30 will have difficulty penetrating below the powder 90 formed by the second blade 22.

[0034] The period of the up-and-down movement of the blade depends on the speed at which the powder 90 is conveyed by the conveying unit 10. In other words, the period of the up-and-down movement of the blade may be determined not with respect to time but with respect to the distance traveled by the powder 90. Specifically, the powder 90 may move 0.7 mm to 2.5 mm during one up-and-down movement of the blade. The period of the up-and-down movement of the blade with respect to time is determined by the relationship between this distance and the speed at which the powder 90 is conveyed.

[0035] If the distance traveled by the powder 90 during one up-and-down movement of the blade is less than 0.7 mm, the efficiency of molding the powder 90 decreases. If the distance traveled by the powder 90 during one up-and-down movement of the blade is longer than 2.5 mm, the molding of the powder 90 becomes insufficient.

[0036] Furthermore, the distance traveled by the powder 90 during one up-and-down movement of the blade may differ depending on the first height of each blade. Specifically, the distance traveled by the powder 90 during one up-and-down movement of a blade having a high first height may be longer than that of a blade having a low first height.

[0037] As described above, the blades break up clumps of the powder 90 during the molding process of the powder 90. A blade with a high first height breaks up larger clumps compared to a blade with a low first height. Because the proportion of such clumps present is small, a blade that breaks up such clumps may require the powder 90 to travel a longer distance during one up-and-down movement.

[0038] In either blade, the shorter the period of up-down movement, the better the state of the molded body of powder 90. However, the shorter the period of up-down movement, the greater the load on the blade drive mechanism. Therefore, the period of up-down movement of the blade may be lengthened depending on the first height.

[0039] Furthermore, the difference (fluctuation range) between the first height and the second height of each of the first blade 21 and the second blade 22 may be 2 mm to 4 mm. If the fluctuation range is less than 2 mm, the powder 90 formed by each of the blades may not be transported smoothly. If the fluctuation range is greater than 4 mm, the blade speed will be excessively high when the transport speed of the powder 90 and the period of the blade's up-and-down movement are set as described above. As a result, the load on the drive mechanism that changes the blade height increases, which may shorten the life of the drive mechanism.

[0040] The fluctuation range of the height of the first blade 21 and the second blade 22 may be the same or different from each other. For example, by making the fluctuation range of the second blade 22 smaller than that of the first blade 21, it is possible to reduce the unevenness of the powder 90 in the conveyance direction.

[0041] The first height and the second height of the first blade 21 and the second blade 22 may be set appropriately so that the powder 90 is molded in stages. Specifically, the first height and the second height of the second blade 22 are set to the lower and upper limits of the final thickness of the powder 90. The first height and the second height of the first blade 21 may be set to be 0 mm to 4 mm higher than the first height and the second height of the second blade 22. When the number of blades is three or more, the difference in the first height and the difference in the second height between adjacent blades may be set to be 0 mm to 4 mm.

[0042] The first side wall 23 may extend along the conveying direction of the powder 90 in the conveying unit 10. The second side wall 24 may face the first side wall 23. That is, the first side wall 23 and the second side wall 24 are side walls provided at both ends in the width direction of the area through which the powder 90 is conveyed. The first side wall 23 and the second side wall 24 may be located on both sides of the first blade 21 and the second blade 22. Furthermore, the first side wall 23 and the second side wall 24 are provided so as to be in contact with the conveying surface 11c of the conveying unit 10.

[0043] The powder 90 conveyed by the first conveying unit 11 is shaped in the height direction by the blade. Furthermore, the powder 90 is shaped in the width direction by the first side wall 23 and the second side wall 24. As a result, it is possible to reduce variation in the amount of powder 90 per unit length in the conveying direction. Therefore, it is possible to make the ratio between the powder 90 and the liquid sprayed by the liquid spraying mechanism 30 uniform.

[0044] The rear wall 25 is located upstream in the conveying direction of the first side wall 23 and the second side wall 24. In the mixer 1, the powder supply mechanism 29 may supply the powder 90 to an area defined by the first side wall 23, the second side wall 24, the rear wall 25, and the first blade 21. That is, the rear wall 25 defines the upstream end in the conveying direction of the area to which the powder 90 is supplied. However, in the mixer 1, the rear wall 25 may be omitted.

[0045] The liquid spraying mechanism 30 sprays a liquid onto the powder 90 formed into a layer. The liquid is, for example, a vehicle or solvent added to the powder 90 composed of ceramic particles. Specific examples of the liquid include an aqueous solution of a water-soluble acrylic resin or an aqueous solution of a polysaccharide. The liquid spraying mechanism 30 may be located downstream of the powder molding mechanism 20 in the direction of transport of the powder 90 by the first transport unit 11. The liquid spraying mechanism 30 may be located above the second transport unit 12. In FIGS. 1 and 2 , the mixing device 1 includes two liquid spraying mechanisms 30 arranged in the width direction. However, the number of liquid spraying mechanisms 30 included in the mixing device 1 is not limited to two, as long as the liquid can be sprayed over the entire powder 90 transported by the second transport unit 12.

[0046] Figure 4 is a cross-sectional view taken along line IV-IV in Figure 2. Figure 4 shows the structure of one liquid spray mechanism 30. As shown in Figure 4, the liquid spray mechanism 30 may include a nozzle 31 and a cover 32.

[0047] The nozzle 31 may be configured to spray liquid onto the powder 90 on the conveying unit 10. The nozzle 31 may be a so-called one-fluid nozzle that sprays only liquid. If the nozzle 31 were a so-called two-fluid nozzle that sprays both liquid and air, the powder 90 could be scattered by the air sprayed from the nozzle 31. By using the nozzle 31 as a one-fluid nozzle, scattering of the powder 90 can be reduced. The nozzle 31 may be connected to a pump (not shown) that supplies liquid. The amount of liquid sprayed from the nozzle 31 may be determined appropriately taking into consideration the desired ratio of the powder 90 to the liquid, the speed at which the powder 90 is conveyed by the conveying unit 10, the amount of powder 90 per unit length in the conveying direction, and the like.

[0048] The cover 32 limits the range of liquid sprayed by the nozzle 31. The cover 32 may have a cylindrical shape with an upper surface to which the nozzle 31 is attached and side surfaces that limit the range of liquid sprayed. The nozzle 31 may be located on the central axis of the cylindrical shape of the cover 32. However, the shape of the cover 32 is not limited to this.

[0049] When viewed from a direction perpendicular to the conveying surface 12c, the entire cover 32 is included in the area where the powder 90 is conveyed. Therefore, liquid sprayed from the nozzle 31 toward outside the liquid spraying range limited by the cover 32 collides with the side of the cover 32 and falls onto the powder 90 located below. This reduces the possibility of the liquid being sprayed outside the area where the powder 90 is present on the conveying unit 10, for example. Therefore, the area where the liquid is sprayed from the nozzle 31 can be limited to the area where the powder 90 is present, making it possible to make the ratio of powder 90 to liquid uniform.

[0050] The cover 32 may be made of a material that does not react with liquid or that has high water repellency. Specific examples of the material for the cover 32 include stainless steel and fluororesin.

[0051] The height H of the end 32a of the cover 32 relative to the conveying unit 10 may be set to be 1 mm to 6 mm higher than the thickness of the molded powder 90. For example, if the thickness of the molded powder 90 is 4 mm, the height H of the end 32a relative to the conveying unit 10 may be 5 mm to 10 mm. If H is less than 5 mm, there is a high possibility that the powder 90 will come into contact with the cover 32 when there is variation in the thickness of the powder 90. If H is greater than 10 mm, there is a possibility that liquid will be dispersed to the outside from between the powder 90 and the end 32a. In other words, it becomes impossible to sufficiently restrict the dispersion range of the liquid.

[0052] FIG. 5 is a side view of the cover 32. As shown in FIG. 5, the end 32a of the cover 32 facing the conveying unit 10 may have a plurality of convex portions 32b that are convex toward the conveying unit 10. The convex portions 32b may be located over the entire end of the cover 32 facing the conveying unit 10. In other words, the end 32a may have a sawtooth shape over its entirety. For simplicity, only some of the convex portions 32b are marked with reference numerals in FIG. 5. The above-mentioned "H" refers to the height of the bottom end of the convex portions 32b relative to the conveying unit 10.

[0053] Because the cover 32 has such a shape, the liquid adhering to the cover 32 is dispersed from each of the multiple protrusions 32b and falls onto the powder 90. Therefore, compared to when the liquid adhering to the cover 32 falls onto the powder 90 from a single point on the end 32a, for example, the unevenness of the amount of liquid dispersed onto the powder 90 from one position to another is reduced.

[0054] However, the end 32a does not necessarily have to have the convex portion 32b over the entire area facing the conveying unit 10. If at least a part of the end 32a has the convex portion 32b, the unevenness of the amount of liquid sprayed can be reduced compared to when the end 32a does not have the convex portion 32b.

[0055] The moving mechanism 40 may be configured to be able to move the powder 90 on the transport surface 12c in a direction different from the transport direction. The moving mechanism 40 is located downstream of the liquid sprinkling mechanism 30 in the transport direction. The moving mechanism 40 may move the powder 90, on which liquid has been sprayed by the liquid sprinkling mechanism 30, in a direction that narrows the width of the area through which the powder 90 is transported.

[0056] The nozzle 31 may spray less liquid near the center and more liquid near the outer edge within, for example, a circular area. When liquid is sprayed by the liquid spraying mechanism 30 having such a nozzle 31, the ratio of liquid to powder 90 tends to be higher at the center in the width direction of the area through which the powder 90 is transported than at the ends in the width direction. By using the movement mechanism 40 to move the powder 90 from the ends in the width direction toward the center, the powder 90 and the liquid can be mixed uniformly.

[0057] In the first embodiment, the movement mechanism 40 includes four rotating bodies 41, 42, 43, and 44. At least a portion of each rotating body 41 may be located on the transport unit 10, specifically, on the second transport unit 12. In FIGS. 1 and 2, the entire rotating bodies 41 to 44 are located on the second transport unit 12.

[0058] The rotors 41 to 44 may be made of any material that does not react with the powder 90 and the liquid sprayed by the liquid spraying mechanism 30. The rotors 41 to 44 may be made of, for example, fluororesin or polyacetal. If the rotors 41 to 44 are made of such a material, the mixture of the powder 90 and the liquid will adhere less. In addition, the rotors 41 to 44 will have wear resistance. Furthermore, the rotors 41 to 44 will be less likely to damage the stainless steel that forms the conveying surface 12c.

[0059] Rotating bodies 41 to 44 are positioned on conveying section 10 so as to cross the widthwise ends of the region through which powder 90 is conveyed. Furthermore, rotating bodies 41 to 44 rotate on the upstream side in the conveying direction in a direction that moves powder 90 toward the center of second conveying section 12. As a result, powder 90 located near the ends of the region through which powder 90 is conveyed moves toward the center of the region.

[0060] Specifically, the rotators 41 and 42 are arranged side by side in the width direction at the same position in the conveying direction. The rotators 41 and 42 are respectively located at both ends in the width direction of the area where the powder 90 is conveyed. The rotator 43 is located downstream of the rotators 41 and 42 in the conveying direction, at one end in the width direction of the area where the powder 90 is conveyed. The rotator 44 is located downstream of the rotator 43 in the conveying direction, on the opposite side of the area where the powder 90 is conveyed from the rotator 43 in the width direction. In other words, the rotators 43 and 44 are arranged offset from each other in the width direction. As a result, each rotator 41 moves the powder 90 from the end side to the center side of the conveying section 10, allowing the powder 90 and the liquid to be mixed more uniformly.

[0061] Furthermore, the rotating body 43 is located at the most downstream side in the width direction of the region through which the powder 90 is transported. The rotating body 44 is located at the most downstream side in the width direction of the region through which the powder 90 is transported, on the opposite side from the rotating body 43. At least a portion of these rotating bodies 43, 44 may be located at a substantial center in the width direction of the region through which the powder 90 is transported on the upstream side of the moving mechanism 40. For example, a region within one-eighth of the width direction length of the region through which the powder 90 is transported on the upstream side of the moving mechanism 40 from the center in the width direction may be considered to be the substantial center.

[0062] The rotation speed of the rotating bodies 41 to 44 may be 100% to 500% of the conveying speed of the powder 90 by the second conveying unit 12. The rotation speed of the rotating bodies 41 to 44 here refers to the movement speed of any point located on the outer edge of the rotating bodies 41 to 44 in the circumferential direction of the rotating bodies 41 to 44.

[0063] When the rotation speed of the rotors 41 to 44 is less than 100% of the powder conveying speed, the detachment of the mixture of powder 90 and liquid from the rotors 41 to 44 decreases. Specifically, the slower the rotation speed of the rotors 41 to 44, the longer the time the mixture is in contact with the surfaces of the rotors 41 to 44. As a result, the cumulative value of pressure due to the subsequent mixture conveyed by the second conveying section 12 increases, and the detachment of the mixture from the rotors 41 to 44 decreases. In particular, when the rotation speed of the rotors 41 to 44 is less than 100% of the powder conveying speed, the detachment of the mixture from the rotors 41 to 44 decreases to the extent that the operation of the mixer 1 is impaired.

[0064] If the rotation speed of the rotating bodies 41 to 44 is greater than 500% of the conveying speed of the powder 90, the difference between the conveying speed of the powder 90 by the second conveying section 12 and the rotation speed of the rotating bodies 41 to 44 becomes too large. As a result, the rotating bodies 41 to 44 are worn and the shear load on the mixture increases.

[0065] The rotation axes of the rotating bodies 41 to 44 may be substantially perpendicular to the conveying surface 12c. For example, if the inclination of the rotation axis with respect to the direction perpendicular to the conveying surface is 5° or less, the rotation axis can be considered to be substantially perpendicular to the conveying surface 12c.

[0066] The cross-sectional shape of the rotors 41 to 44 in a plane including the rotation axis may be an isosceles trapezoid in which the upper side is shorter than the lower side. When the cross-sections of the rotors 41 to 44 have such a shape, the mixture of powder 90 and liquid can be easily released from the second conveying section 12. This release property improves as the upper side in the cross-section becomes shorter. On the other hand, the effect of mixing the powder 90 and liquid decreases as the upper side in the cross-section becomes shorter. However, the cross-sectional shape of the rotor 41 is not limited to this and may be, for example, rectangular.

[0067] Furthermore, the moving mechanism 40 is not limited to one including four rotating bodies 41 to 44. When the moving mechanism 40 includes rotating bodies, it may include at least one rotating body on each side in the width direction of the area to which the powder 90 is transported. Furthermore, the moving mechanism 40 is not limited to one including rotating bodies.

[0068] The control unit 50 may be configured to be able to comprehensively control the operation of each unit included in the mixing device 1. For example, the control unit 50 may control the up and down movement of the first blade 21 and the second blade 22 by controlling the drive mechanism. The control unit 50 may also control the conveying speed of the powder 90 by the first conveying unit 11 and the second conveying unit 12. The control unit 50 may also control the amount of liquid sprayed from the nozzle 31. The control unit 50 may also control the rotation speed of the rotating bodies 41 to 44.

[0069] The storage unit 60 is a storage medium that stores information necessary for control by the control unit 50. The storage unit 60 may store, for example, programs for the various controls described above. However, the mixing device 1 does not necessarily need to include the storage unit 60, and may be communicably connected to an external storage device that stores information necessary for control by the control unit 50.

[0070] (Method for Producing Mixture) Fig. 6 is a flowchart showing an example of a method for producing a mixture using the mixing device 1. An example of a method for producing a mixture using the mixing device 1 will be described below.

[0071] In the mixing device 1, the control unit 50 controls the conveying unit 10 to convey the powder 90 (S1, conveying step). The control unit 50 continuously conveys the powder 90 during the manufacturing process of the mixture.

[0072] In step S1, the control unit 50 causes the powder 90 being conveyed to be formed into a layer by the powder forming mechanism 20 (S2, powder forming step). Subsequently, the control unit 50 causes the liquid spraying mechanism 30 to spray liquid onto the powder 90 formed into a layer in step S2 (S3, liquid spraying step). Furthermore, the control unit 50 causes the movement mechanism 40 to move the powder 90 onto which the liquid has been sprayed in step S3 in a direction different from the conveyance direction (S4).

[0073] Through the above steps, a mixture can be produced using the mixing device 1. However, the method for producing a mixture using the mixing device 1 is not limited to the above example. For example, the control unit 50 may cause the conveying unit 10 to convey the powder 90 intermittently.

[0074] Example A mixture of alumina powder and water-soluble acrylic resin was produced using the mixing device 1. Specifically, alumina powder with a particle size D50 of 1.5 μm was formed into a layer with an average thickness of 3 mm using the powder forming mechanism 20. A 5 wt % aqueous solution of water-soluble acrylic resin (acrylic aqueous solution) was sprayed onto the layered alumina powder using the liquid spraying mechanism 30. The weight ratio of the alumina powder to the acrylic aqueous solution was 81:19.

[0075] The mixture obtained under the above conditions was in the form of granules, which could be molded into a desired shape by, for example, a known pressing method using a mold.

[0076] In the mixture obtained under the above conditions, the volume fraction of the alumina powder was 52.2 vol%, and the volume fraction of the acrylic aqueous solution was 47.8 vol%. Because the fluidity of a mixture with these volume fractions is low, it is difficult to knead a mixture with the same volume fractions using, for example, a conventional kneader equipped with rotating blades. In other words, the mixing device 1 can produce a mixture with a high powder volume fraction, which is difficult to knead using a conventional kneader.

[0077] One method for obtaining a ceramic structure of a desired shape is to mix powdered ceramic with a liquid containing a binder, mold the mixture, and then sinter it to remove the binder. The mixture is sintered at a temperature of 300°C or higher. During this process, the binder is converted into carbon dioxide and water and released into the atmosphere.

[0078] The mixing device 1 can reduce the amount of carbon dioxide emitted during the manufacturing process of a ceramic structure by producing a mixture with a small amount of binder. This effect also contributes to achieving, for example, Goal 13 of the Sustainable Development Goals (SDGs) advocated by the United Nations, "Take urgent action to combat climate change."

[0079] [Embodiment 2] Fig. 7 is a perspective view showing the configuration of a mixing device 1A according to embodiment 2. Fig. 8 is a cross-sectional view showing the configuration of a powder molding mechanism 20A. As shown in Figs. 7 and 8, the mixing device 1A includes a conveying unit 10A, a powder molding mechanism 20A, and a moving mechanism 40A.

[0080] The mixing apparatus 1A also includes a liquid sprinkling mechanism 30 having the same structure as the liquid sprinkling mechanism 30 included in the mixing apparatus 1. However, while the mixing apparatus 1 includes two liquid sprinkling mechanisms 30, the mixing apparatus 1A includes only one liquid sprinkling mechanism 30. Furthermore, the mixing apparatus 1A may include a control unit and a memory unit (not shown) that control the conveying unit 10A, the powder molding mechanism 20A, the liquid sprinkling mechanism 30, and the moving mechanism 40A.

[0081] The conveying unit 10A conveys powder. The conveying unit 10A differs from the conveying unit 10 in that it is a single conveying unit and does not include the first conveying unit 11 and the second conveying unit 12. Therefore, the powder molding mechanism 20A, the liquid spraying mechanism 30, and the moving mechanism 40A are located on the single conveying unit.

[0082] A third scraping plate 15 for scraping powder from the conveying section 10A may be provided at the downstream end of the conveying section 10A in the conveying direction. The third scraping plate 15 can scrape the powder from the conveying section 10A and allow it to fall from the end of the conveying section 10A. A container for collecting the mixture, for example, may be provided below the end of the conveying section 10A.

[0083] The powder forming mechanism 20A forms the powder into a layer. The powder forming mechanism 20A differs from the powder forming mechanism 20 in that the powder forming mechanism 20A does not include the first blade 21 and the second blade 22, but includes only a single third blade 26 (blade).

[0084] The height of the third blade 26 varies between a first height and a second height higher than the first height while the powder is being conveyed by the conveying unit 10A. The third blade 26 molds the powder to the first height on the third blade 26.

[0085] In the powder molding mechanism 20A, the height of the powder molded by the third blade 26 is the height at which the powder will ultimately be molded. Therefore, the first height of the third blade 26 is set to the height at which the powder will ultimately be molded.

[0086] 9 is a plan view of the moving mechanism 40A and its surroundings. The moving mechanism 40A moves the powder on the conveying surface along which the conveying unit 10A conveys the powder in a direction different from the direction of powder conveyance by the conveying unit 10A. The moving mechanism 40A differs from the moving mechanism 40 in that it includes two rotating bodies 45 and 46. The rotating body 45 is located on one side in the width direction of the area through which the powder 90 is conveyed. The rotating body 46 is located on the opposite side in the width direction from the rotating body 45 of the area through which the powder 90 is conveyed.

[0087] As described above, the mixer 1A has a simpler configuration than the mixer 1. Such a mixer 1A can also produce a mixture of powder and liquid with a high powder volume fraction. Therefore, for example, the amount of binder used in the manufacturing process of a ceramic structure can be reduced, and the amount of carbon dioxide emitted can also be reduced.

[0088] The invention according to the present disclosure has been described above based on the drawings and examples. However, the invention according to the present disclosure is not limited to the above-described embodiments. In other words, the invention according to the present disclosure can be modified in various ways within the scope of the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that a person skilled in the art can easily make various modifications or corrections based on the present disclosure. It should also be noted that these modifications or corrections are included in the scope of the present disclosure.

[0089] For example, conveying side walls may be provided on both ends in the width direction downstream of the powder forming mechanism 20. The conveying side walls are provided so as to contact the conveying surface 11c (12c) of the conveying section 10. By providing the conveying side walls on the conveying surface 11c (12c) in this way, the width direction length of the powder coming out of the powder forming mechanism 20 is controlled to be constant. Therefore, changes in the width direction of the powder due to the influence of vibrations during conveyance, etc. are reduced, and as a result, variations in the thickness of the powder can be reduced.

[0090] Furthermore, when a rotor is provided as the movement mechanism 40 at one end in the width direction of the region where the powder 90 is transported, a side wall for the movement mechanism may be provided at the other end in the width direction. In this case, the side wall for the movement mechanism can prevent the powder 90 passing through the rotor from spreading to the other end in the width direction.

[0091] REFERENCE SIGNS LIST 1, 1A Mixing device 10, 10A Conveying section 11 First conveying section 12 Second conveying section 20, 20A Powder molding mechanism 21 First blade (blade) 22 Second blade (blade) 23 First side wall 24 Second side wall 26 Third blade (blade) 30 Liquid spraying mechanism 31 Nozzle 32 Cover 32a Convex portion 40, 40A Moving mechanism 41, 42, 43, 44, 45, 46 Rotating body

Claims

1. A conveying unit for conveying powder, a powder forming mechanism for forming the powder into a layer, a liquid spraying mechanism for spraying a liquid onto the powder formed in a layer, comprising: the powder forming mechanism includes one or more blades for forming the powder in a height direction with respect to the conveying unit, a mixing device in which the height of the blade with respect to the conveying unit varies between a first height and a second height higher than the first height during the conveyance of the powder by the conveying unit.

2. The powder forming mechanism further includes a first side wall of the conveying unit extending along the conveying direction of the powder, and a second side wall facing the first side wall. The mixing device according to claim 1.

3. The mixing device according to claim 2, having a plurality of the blades along the conveying direction of the powder by the conveying unit, and the first height of the blade located on the downstream side in the conveying direction is lower than the first height of the blade located on the upstream side in the conveying direction.

4. The liquid spraying mechanism includes a nozzle for spraying the liquid onto the powder on the conveying unit, and a cover for restricting the spraying range of the liquid. The mixing device according to claim 1.

5. The mixing device according to claim 4, wherein an end of the cover facing the conveying unit has a plurality of convex portions convex toward the conveying unit.

6. The conveying unit includes a first conveying unit to which the powder is supplied, and a second conveying unit located below the first conveying unit and conveying the powder that has fallen from the first conveying unit. The mixing device according to claim 1.

7. The mixing device according to claim 6, wherein a first conveying speed of the powder by the first conveying unit and a second conveying speed of the powder by the second conveying unit are different from each other.

8. A moving mechanism for moving the powder in a direction different from the conveying direction of the powder by the conveying unit on a conveying surface where the conveying unit conveys the powder is provided on a downstream side of the liquid spraying mechanism in the conveying direction. The mixing device according to any one of claims 1 to 7.

9. The moving mechanism includes a rotating body at least partially located above the conveying unit. The mixing device according to claim 8.

10. A conveying unit for conveying powder, a powder forming mechanism for forming the powder into a layer, a liquid spraying mechanism for spraying a liquid onto the powder formed in a layer, comprising: The powder forming mechanism includes one or more blades for forming the powder in the height direction with respect to the conveying unit. A method for producing a mixture using a mixing device in which the height of the blade with respect to the conveying unit varies between a first height and a second height higher than the first height during the conveyance of the powder by the conveying unit. A conveying step of conveying the powder by the conveying unit. A powder forming step of forming the powder being conveyed in the conveying step into a layer by the powder forming mechanism. A method for producing a mixture, comprising: a liquid spraying step of spraying a liquid onto the powder formed into a layer in the powder forming step by the liquid spraying mechanism.