Grain mills and grinding rolls

Abstract

To provide a grain milling machine which is improved from at least one standpoint out of maintenance and productivity.SOLUTION: A grain milling machine comprises: a rotatable shaft; and at least one grinding roll arrayed coaxially along the shaft and fixed to the shaft so as to surround the shaft in a circumferential direction. At least one grinding roll comprises: a cylindrical base; and an abrasive grain layer having abrasive grains electro-deposited or welded onto an outer peripheral surface of the cylindrical base.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to techniques for milling grain. [Background technology]

[0002] Grain polishers equipped with grinding rolls that grind grains using grindstones have been known for some time. For example, Patent Document 1 below discloses a vertical grain polisher equipped with grinding rolls known as Kongo rolls. This grain polisher has seven grinding rolls coaxially attached to a rotating shaft. This allows the weight of one grinding roll to be kept to a level that can be carried by a single worker. As a result, the burden of replacing the grinding rolls when they wear out can be reduced. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2018-8241 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned grain polishing machines still have room for improvement. For example, the kongou rolls are relatively susceptible to wear, so they need to be replaced frequently (e.g., once every six months), which increases the workload of the replacement work. Furthermore, the roll replacement work must be performed while the machine is stopped, which reduces productivity. Furthermore, when grinding rolls are arranged coaxially in multiple tiers, the wear of the grinding rolls is not uniform among them. Therefore, to extend the life of the grinding rolls, the order of the grinding rolls is changed (hereinafter referred to as grinding roll rotation) depending on the wear status of each grinding roll. Such a change also increases the workload and reduces productivity. These problems are not limited to vertical grain polishing machines, but are also common to horizontal grain polishing machines.

[0005] For these reasons, there is a need to provide a grain milling machine that is improved in terms of at least one of maintenance and productivity. [Means for solving the problem]

[0006] The present invention has been made to solve the above-mentioned problems, and can be realized, for example, in the following forms.

[0007] According to a first aspect of the present invention, there is provided a grain polishing machine comprising a rotatable shaft and at least one grinding roll arranged coaxially along the shaft and fixed to the shaft so as to circumferentially surround the shaft, wherein the at least one grinding roll comprises a cylindrical base and an abrasive layer having abrasive grains electroplated or welded to the outer peripheral surface of the cylindrical base.

[0008] This grain polisher uses at least one grinding roll with abrasive grains electroplated or welded to the outer peripheral surface of a cylindrical base. This grinding roll has superior wear resistance compared to a kongou roll, so the frequency of grinding roll replacement can be reduced. In addition, it is lighter than a kongou roll, so if the weight of one grinding roll is set to the same as the weight of a conventional kongou roll (a weight that can be carried by a single worker, for example, 25 kg or less), the number of grinding rolls can be reduced. Therefore, when multiple grinding rolls are used, the frequency of grinding roll rotation can be reduced. This improves maintainability. Furthermore, the number of times the grain polisher needs to be stopped for maintenance is reduced, improving productivity.

[0009] According to a second aspect of the present invention, the at least one grinding roll of the first aspect includes a plurality of grinding rolls. A flow passage for circulating air in the axial direction of the shaft is formed inside the plurality of grinding rolls. The grain polisher further includes an intermediate member disposed between two adjacent cylindrical bases so as to form a communication passage that connects the flow passage with the outside of the grinding roll. The intermediate member includes at least one annular portion that extends annularly from a position corresponding to the cylindrical base in the axial direction toward the radially inward direction of the cylindrical base, and is disposed adjacent to the communication passage. According to this aspect, an airflow is generated that flows from the flow passage inside the grinding roll through the communication passage toward the radially outward direction, thereby facilitating separation of the polished grain husks. Furthermore, even if grains enter the communication passage from outside the grinding roll, the grains remain on at least one annular portion before entering the flow passage, providing an opportunity for the grains to be discharged outside the grinding roll. This prevents grains from entering the flow passage from outside the grinding roll via the communication passage. As a result, the load of cleaning the inside of the grinding roll can be reduced.

[0010] According to a third aspect of the present invention, in the second aspect, the shaft is arranged to extend in the vertical direction, and the at least one annular portion includes a lower annular portion arranged below the communication passage. This aspect can efficiently prevent grains from entering the flow passage.

[0011] According to a fourth aspect of the present invention, in the third aspect, the upper portion of the radially outer edge of the lower annular portion has a chamfered shape. This aspect prevents the grains supplied from above around the grinding roll from being blocked by the radially outer edge of the lower annular portion and flowing downward. Furthermore, it prevents the grains flowing downward from colliding with the radially outer edge of the lower annular portion and entering the communication passage.

[0012] According to a fifth aspect of the present invention, in the third or fourth aspect, the at least one annular portion includes an upper annular portion disposed above the communication passage. This provides an opportunity for grains that bounce upward and radially inward at the intermediate member to collide with the upper annular portion before entering the flow passage and be discharged outside the grinding roll. This further prevents grains from entering the flow passage.

[0013] According to a sixth aspect of the present invention, in any one of the third to fifth aspects, the intermediate member includes a plurality of arms extending radially at least above the lower annular portion. The spaces between the plurality of arms function as communication passages. With this aspect, even if grains enter the communication passage from outside the grinding roll, the plurality of arms can repel the grains to the outside of the grinding roll. Therefore, the grains can be further prevented from entering the flow passage. The plurality of arms may be in contact with the lower annular portion or may be spaced apart from each other. Alternatively, the plurality of arms may be formed integrally with the lower annular portion.

[0014] According to a seventh aspect of the present invention, in any one of the third to fifth aspects, the intermediate member has a wall portion that protrudes upward from the lower annular portion and extends at least partially in the circumferential direction along the lower annular portion. A portion of the lower annular portion where no wall portion is formed or a portion where the protruding height of the wall portion is relatively low functions as a communication passage. According to this aspect, the wall portion can further prevent grains from entering the flow passage.

[0015] According to the eighth aspect of the present invention, in the first aspect, at least one grinding roll has a flow passage formed therein for circulating air in the axial direction of the shaft. The at least one grinding roll has an upper edge, a lower edge, a communication passage disposed between the upper and lower edge portions and connecting the flow passage with the outside of the grinding roll, and at least one annular portion extending annularly from a position corresponding to the cylindrical base in the axial direction toward the radially inward direction of the cylindrical base, the at least one annular portion being disposed adjacent to the communication passage. This aspect provides the same effects as the second aspect.

[0016] According to a ninth aspect of the present invention, there is provided a grinding roll. This grinding roll includes a cylindrical base and an abrasive layer having abrasive grains electrodeposited or welded to the outer peripheral surface of the cylindrical base. With this grinding roll, the same effects as those of the first aspect can be obtained. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic configuration diagram of a grain polishing machine according to a first embodiment. FIG. [Figure 2] FIG. [Figure 3] FIG. 2 is a cross-sectional view showing the periphery of a grinding roll. [Figure 4] FIG. 2 is an exploded perspective view of a grinding roll and an intermediate member. [Figure 5] FIG. 10 is an exploded perspective view showing an intermediate member according to a second embodiment. [Figure 6] FIG. 10 is an exploded perspective view showing an intermediate member according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] FIG. 1 is a schematic diagram of a grain polisher 10 according to a first embodiment, partially shown in cross section. In this embodiment, the grain polisher 10 is used to polish brown rice, but the grain to be processed by the grain polisher 10 is not limited to rice and may be any grain (e.g., wheat, corn, etc.). As shown in FIG. 1, the grain polisher 10 includes an inlet 21, a grain polishing section 30, and an outlet 22. The grain polishing section 30 includes multiple (three in the example of FIG. 1) grinding rolls 50a-50c, a bran removal chamber cover 31, and an outer cylinder 32. The three grinding rolls 50a-50c are arranged coaxially in the vertical direction along the shaft 40. In this embodiment, the grain polisher 10 is a vertical grain polisher, and the shaft 40 is arranged to extend in the vertical direction. The grinding rolls 50a-50c are fixed to the upper portion of the shaft 40 so as to surround the shaft 40 in the circumferential direction.

[0019] Shaft 40 is rotatably supported by bearings 41 and 42. Shaft 40 is rotated by a rotational driving force provided by motor 25. Specifically, the rotational driving force is transmitted from motor 25 to shaft 40 via drive pulley 26 fixed to the output shaft of motor 25, driven pulley 27 fixed to the lower end of shaft 40, and endless V-belt 28 wound between drive pulley 26 and driven pulley 27.

[0020] The outer cylinder 32 surrounds the grinding rolls 50a-50c in the circumferential direction. The outer cylinder 32 has a mesh structure with a plurality of through holes that penetrate in the radial direction. The annular space between the grinding rolls 50a-50c and the outer cylinder 32 forms the polishing chamber 33. Brown rice fed through the feed port 21 is led into the polishing chamber 33. A resistor 35 is disposed so as to partially protrude into the polishing chamber 33 and face the grinding rolls 50a-50c. The resistor 35 is an elongated member extending vertically, and applies resistance to the circumferential movement of the brown rice within the polishing chamber 33. The amount of protrusion of the resistor 35 into the polishing chamber 33 (in other words, the clearance between the grinding rolls 50a-50c and the resistor 35) can be adjusted by operating the adjustment handle 36.

[0021] Brown rice is supplied to the polishing chamber 33, and when the grinding rolls 50a-50c are rotated by the rotational driving force of the motor 25, the brown rice is ground by the grinding rolls 50a-50c and the outer cylinder 32. By grinding the surface of the brown rice, the bran layer is peeled off, and white rice is obtained. The polished white rice is guided to the discharge outlet 22 located below the polishing chamber 33 and discharged through the discharge chute 23.

[0022] The bran removal chamber cover 31 circumferentially surrounds the outer cylinder 32. The annular space between the outer cylinder 32 and the bran removal chamber cover 31 forms a bran removal chamber 34. The bran peeled from the brown rice in the husk milling chamber 33 is guided to the bran removal chamber 34 through the mesh of the outer cylinder 32, and further to the bran collection chamber 24 located below the bran removal chamber 34. The air in the bran collection chamber 24 is sucked in by a suction fan (not shown) through an exhaust duct (see Figure 1). Therefore, the bran in the bran collection chamber 24 is sucked in through the exhaust duct and collected.

[0023] FIG. 2 is a perspective view of grinding rolls 50a to 50c. As shown in FIG. 2, the grinding roll 50a includes a cylindrical base 51. In this embodiment, the cylindrical base 51 has a cylindrical shape, but may have any cylindrical shape. An abrasive layer 52 is formed on the outer peripheral surface of the cylindrical base 51 by electrodepositing or welding abrasive grains. In this embodiment, superabrasive grains (CBN or diamond) are used as the abrasive grains, but other types of abrasive grains that can be electrodeposited or welded may also be used. The cylindrical base 51 may be formed from any material that can be electrodeposited or welded (for example, a metal such as stainless steel, a resin with a plated surface, etc.).

[0024] The cylindrical base 51 is hollow, but its rigidity is increased by a reinforcing plate 53 disposed therein. The reinforcing plate 53 has a plurality of ventilation holes 54 that penetrate the reinforcing plate 53 in the vertical direction. The plurality of ventilation holes 54 are arranged along the circumferential direction. The grinding rolls 50b and 50c have the same configuration as the grinding roll 50a.

[0025] Fig. 3 is a cross-sectional view showing the periphery of the grinding rolls 50a to 50c. Fig. 4 is an exploded perspective view of the grinding rolls 50a, 50b and the intermediate member 60. As shown in Figs. 3 and 4, the grinding rolls 50a to 50c are fixed to the shaft 40 via bosses 57. A feed roller 55 for sending brown rice into the polishing chamber 33 is disposed above the grinding roll 50a. A ring 56 for guiding the brown rice radially outward (and thus to the discharge chute 23) is disposed below the grinding roll 50c.

[0026] As shown in Figures 3 and 4, intermediate members 60 are disposed between the grinding rolls 50a and 50b, and between the grinding rolls 50b and 50c (in other words, between two adjacent cylindrical bases 51). For simplicity, the intermediate member 60 and the grinding roll 50c disposed between the grinding roll 50b and the ring 56 are not shown in Figure 4. The intermediate member 60 includes a first intermediate member 70, a second intermediate member 80, and a third intermediate member 90. The first intermediate member 70, the second intermediate member 80, and the third intermediate member 90 are disposed in this order from the bottom up.

[0027] As shown in FIG. 4 , the first intermediate member 70 has a disk shape. A shaft through-hole 71 is formed in the center of the first intermediate member 70, through which the shaft 40 passes. A plurality of ventilation holes 72 are formed radially outward from the shaft through-hole 71, penetrating the first intermediate member 70 in the vertical direction. The ventilation holes 72 are arranged along the circumferential direction. The first intermediate member 70 has an annular portion 73. The annular portion 73 is a portion that extends annularly from a position corresponding to the cylindrical base 51 as seen in the direction in which the axis AX1 of the shaft 40 extends (hereinafter referred to as the axial direction) to a position radially inward from the cylindrical base 51. In other words, the annular portion 73 is a portion that extends from the radially outer edge of the first intermediate member 70 to the radially outer edge of the ventilation holes 72. The annular portion 73 is a non-limiting example of a “lower annular portion” in the claims. As shown in FIGS. 2 and 4, an upper portion 74 of the radially outer edge of the first intermediate member 70 has a chamfered shape.

[0028] As shown in FIG. 4, the second intermediate member 80 includes a base 82 and a plurality of arms 83 (eight in the example of FIG. 4). The base 82 is a portion that circumferentially surrounds the shaft 40. A shaft through-hole 81 is formed in the center of the base 82, through which the shaft 40 passes. The plurality of arms 83 extend radially outward from the base 82. As shown in FIGS. 2 and 4, the arms 83 extend above the annular portion 73 to the vicinity of the radially outer edge of the first intermediate member 70. In this embodiment, the arms 83 have a shape that is slightly bent midway from the base end to the tip end. However, the arms 83 may have any shape.

[0029] 4, the third intermediate member 90 has the same size and shape as the first intermediate member 70, except that the third intermediate member 90 does not have the chamfered outer edge upper portion 74. Like the first intermediate member 70, the third intermediate member 90 includes a shaft through-hole 91, a plurality of ventilation holes 92, and an annular portion 93. The annular portion 93 is a non-limiting example of an "upper annular portion" in the claims.

[0030] Inside the grinding rolls 50a to 50c, a flow passage 58 is formed for circulating air in the axial direction of the shaft 40. Specifically, as shown in Figures 3 and 4, by driving a suction fan (not shown), the flow passage 58 is formed so as to pass through the ventilation holes 54 of each of the grinding rolls 50a to 50c, the ventilation holes 92 of the third intermediate member 90, the spaces between the multiple arms 83 of the second intermediate member 80, and the ventilation holes 72 of the first intermediate member 70.

[0031] 2 to 4, the spaces between the arms 83 of the second intermediate member 80 form communication passages 59 that connect the flow passages 58 with the outside of the grinding rolls 50a to 50c. The communication passages 59 are adjacent to the annular portion 73 of the first intermediate member 70 located below the communication passages 59 and the annular portion 93 of the third intermediate member 90 located above the communication passages 59. Air flows radially outward from the flow passages 58 inside the grinding rolls 50a to 50c through the communication passages 59, generating an airflow that flows from the pounding chamber 33 to the bran removal chamber 34, thereby facilitating bran separation.

[0032] In this embodiment, the arm 83 of the second intermediate member 80 is disposed at a position that does not overlap with the ventilation holes 72, 92 when viewed in the axial direction, thereby enabling smooth air circulation within the flow passage 58. However, the positional relationship between the arm 83 and the ventilation holes 72, 92 can be set arbitrarily.

[0033] The grain polisher 10 described above uses multiple grinding rolls 50a-50c, each with abrasive grains electrodeposited or welded to the outer peripheral surface of a cylindrical base 51. The grinding rolls 50a-50c have superior wear resistance compared to a carbide roll, reducing the frequency of replacement or rotation of the grinding rolls 50a-50c and the frequency of position adjustment of the resistor 35 (adjusting the clearance between the grinding rolls 50a-50c and the resistor 35). Furthermore, because they are lighter than a carbide roll, the number of grinding rolls can be reduced by setting the weight of each grinding roll to the same weight as a conventional carbide roll (a weight that can be carried by a single worker, e.g., around 25 kg). This further reduces the frequency of rotation of the grinding rolls. This improves maintainability. Furthermore, the grain polisher 10 is less likely to be shut down for maintenance, improving productivity. Furthermore, even if the height of each grinding roll increases by reducing the number of grinding rolls, the grinding rolls 50a to 50c have excellent wear resistance as described above, so uneven wear within each grinding roll is unlikely to occur. Therefore, the refining performance is not reduced due to the increase in the height of each grinding roll.

[0034] Furthermore, according to the grain polisher 10, even if brown rice enters the connecting passage 59 from outside the grinding rolls 50a to 50c, the brown rice remains on the annular portion 73 of the first intermediate member 70 before entering the flow passage 58, providing an opportunity for the brown rice to be discharged outside the grinding rolls 50a to 50c. Therefore, brown rice is prevented from entering the flow passage 58 from outside the grinding rolls 50a to 50c via the connecting passage 59. As a result, the cleaning load on the inside of the grinding rolls 50a to 50c can be reduced. In addition, brown rice that bounces upward and radially inward at the first intermediate member 70 or the second intermediate member 80 collides with the annular portion 93 of the third intermediate member 90 before entering the flow passage 58, providing an opportunity for the brown rice to be discharged outside the grinding rolls 50a to 50c. Therefore, brown rice is further prevented from entering the flow passage 58.

[0035] Furthermore, according to the grain polisher 10, even if brown rice enters the communication passage 59 from outside the grinding rolls 50a to 50c, the arm 83 of the second intermediate member 80 can push the brown rice out of the grinding rolls 50a to 50c. Therefore, the brown rice can be further prevented from entering the flow passage 58.

[0036] In this embodiment, the ventilation holes 54 of the grinding rolls 50a to 50c are larger than the ventilation holes 72 of the first intermediate member 70 and the ventilation holes 92 of the third intermediate member 90, and the radially outer edges of the ventilation holes 72, 92 are located radially inward of the radially outer edge of the ventilation hole 54. This makes it possible to achieve both a reduction in the weight of the grinding rolls 50a to 50c and the effect of suppressing brown rice from entering the flow passages 58.

[0037] Furthermore, according to the grain polisher 10, the upper outer edge portion 74 of the first intermediate member 70 has a chamfered shape. This prevents the flow of brown rice that is supplied from above around the grinding rolls 50a-50c and flows downward from being obstructed by the upper outer edge portion 74. It also prevents the brown rice flowing downward from colliding with the upper outer edge portion 74 and entering the communicating passage 59.

[0038] The second embodiment will be described below with reference to Figure 5. The grain polishing machine 10 according to the second embodiment differs from the first embodiment only in that it is equipped with an intermediate member 160 instead of the intermediate member 60. Only the differences from the first embodiment will be described below. As shown in Figure 5, the intermediate member 160 is equipped with a first intermediate member 170 instead of the first intermediate member 70 and second intermediate member 80 according to the first embodiment.

[0039] The first intermediate member 170 has a disk shape and, like the first intermediate member 70, has a shaft through-hole 71 and a plurality of ventilation holes 72. The first intermediate member 170 further has an annular portion 173. The annular portion 173 is a portion that extends annularly from a position corresponding to the cylindrical base 51 when viewed in the axial direction toward a position radially inward from the cylindrical base 51. A plurality of arms 175 extend radially from the upper surface of the first intermediate member 170. The spaces between the plurality of arms 175 function as communication paths 159.

[0040] Such an intermediate member 160 can also provide the same effect as the intermediate member 60. In other words, the first intermediate member 170 has a shape similar to the member obtained by integrating the first intermediate member 70 and the second intermediate member 80 according to the first embodiment, and has the functions of both the first intermediate member 70 and the second intermediate member 80.

[0041] The third embodiment will be described below with reference to Figure 6. The grain polishing machine 10 according to the third embodiment differs from the first embodiment only in that it is equipped with an intermediate member 260 instead of the intermediate member 60. Only the differences from the first embodiment will be described below. As shown in Figure 6, the intermediate member 260 is equipped with a first intermediate member 270 instead of the first intermediate member 70 and second intermediate member 80 according to the first embodiment.

[0042] The first intermediate member 270 has a disk shape and, like the first intermediate member 70, includes a shaft through-hole 71 and a plurality of ventilation holes 72. The first intermediate member 270 further includes an annular portion 273. The annular portion 273 is a portion that extends annularly from a position corresponding to the cylindrical base 51 when viewed in the axial direction toward a position radially inward from the cylindrical base 51. The first intermediate member 270 further includes a plurality of wall portions 275 that protrude upward from the annular portion 273. Each of the plurality of wall portions 275 extends partially in the circumferential direction along the annular portion 273. A portion of the annular portion 273 where the wall portion 275 is not formed functions as a communicating passage 259.

[0043] Even with such intermediate member 260, the wall portion 275 and the annular portion 273 can prevent brown rice from entering the flow passage 58 while ensuring the communication passage 259. In an alternative embodiment, one wall portion may extend circumferentially along the entire circumference of the annular portion 273. In this case, the one wall portion may have a portion with a relatively high protruding height and a portion with a low protruding height. With this configuration, the portion with a relatively low protruding height can function as a communication passage.

[0044] Although the embodiments of the present invention have been described above, the above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and the present invention includes equivalents thereof. Furthermore, any combination or omission of the components described in the claims and specification is possible within the scope of solving at least part of the above-described problems or achieving at least part of the effects.

[0045] For example, the third intermediate member 90 can be omitted. Alternatively, the intermediate members 60, 160, and 260 can be modified into any shape and structure as long as they are disposed between two adjacent cylindrical bases 51 so as to form a communication passage that connects the flow passage 58 with the outside of the grinding rolls 50a to 50c, and an annular portion extending radially inward from a position corresponding to the cylindrical base 51 as viewed in the axial direction is disposed adjacent to the communication passage. Such intermediate members may include multiple individual parts that are individually fixed to the shaft 40, or may include a member formed by integrating multiple parts by any fixing means (e.g., bolting, welding, etc.). Furthermore, such intermediate members may be attached to the upper and / or lower edge portions of the cylindrical bases 51 by any fixing means. Alternatively, the intermediate members may be a single part integrally molded by casting or the like.

[0046] Alternatively, the number of grinding rolls can be set to any number greater than or equal to one.

[0047] Alternatively, when there is only one grinding roll, the intermediate member 60 may be omitted, and a communication passage and at least one annular portion disposed adjacent to the communication passage may be disposed between the upper and lower edges of the grinding roll. In this case, the communication passage may be formed, for example, by grinding the grinding roll and the cylindrical base. Furthermore, the at least one annular portion may be fixed to the interior of the cylindrical base by any fixing means. Even when there are two or more grinding rolls, the intermediate member 60 may be omitted, and such a configuration may be adopted.

[0048] Alternatively, the grain polisher 10 can be converted into a horizontal grain polisher. [Explanation of symbols]

[0049] 10...Grain milling machine 21...Inlet 22...Exhaust port 23...Discharge chute 24...Nuka room 25...Motor 26...Drive pulley 27...Driven pulley 30...Grain milling section 31...Bran removal chamber cover 32...Outer cylinder 33...Pumping sperm chamber 34...Blank removal room 35...Resistor 36...Adjustment handle 40...shaft 41,42...Bearings 50a, 50b, 50c...Grinding rolls 51...Cylindrical base 52...Abrasive layer 53...Reinforcement plate 54...ventilation hole 55...Feed roller 56...Ring 57...Boss 58... Distribution path 59,159,259...Communication path 60, 160, 260...Intermediate parts 70, 170, 270...First intermediate part 71...Shaft through hole 72...ventilation hole 73,173,273...Circular section 74...Upper outer edge 80...Second intermediate member 81...Shaft through hole 82...Base 83...Arm 90...Third intermediate member 91...Shaft through hole 92...ventilation hole 93...Ring 175...Arm 275...Wall AX1...Axis line

Claims

1. A grain milling machine, a rotatable shaft; at least one grinding roll arranged coaxially along the shaft and fixed to the shaft so as to surround the shaft in the circumferential direction; Equipped with The at least one grinding roll comprises a cylindrical base and an abrasive grain layer having abrasive grains electroplated or welded to an outer peripheral surface of the cylindrical base; the at least one grinding roll comprises a plurality of grinding rolls; A flow passage for circulating air in the axial direction of the shaft is formed inside the plurality of grinding rolls, The grain polishing machine further includes an intermediate member disposed between two adjacent cylindrical bases so as to form a communication passage that connects the flow passage with the outside of the grinding roll; The intermediate member includes at least one annular portion that extends annularly from a position corresponding to the cylindrical base as viewed in the axial direction toward a radially inner side of the cylindrical base, and that is disposed adjacent to the communication passage. Grain milling machine.

2. 2. The grain milling machine according to claim 1, The shaft is arranged to extend in a vertical direction, The at least one annular portion includes a lower annular portion disposed below the communication passage. Grain milling machine.

3. 3. The grain milling machine according to claim 2, The upper portion of the radially outer edge of the lower annular portion has a chamfered shape. Grain milling machine.

4. The grain milling machine according to claim 2 or claim 3, The at least one annular portion includes an upper annular portion disposed above the communication passage. Grain milling machine.

5. A grain milling machine according to any one of claims 2 to 4, the intermediate member includes a plurality of arms extending radially above at least the lower annular portion, The spaces between the arms function as the communication passages. Grain milling machine.

6. A grain milling machine according to any one of claims 2 to 4, the intermediate member includes a wall portion that projects upward from the lower annular portion and extends at least partially circumferentially along the lower annular portion, In the lower annular portion, a portion where the wall portion is not formed or a portion where the protruding height of the wall portion is relatively low functions as the communication passage. Grain milling machine.

7. A grain polishing machine, a rotatable shaft; at least one grinding roll arranged coaxially along the shaft and fixed to the shaft so as to surround the shaft in the circumferential direction; Equipped with The at least one grinding roll comprises a cylindrical base and an abrasive grain layer having abrasive grains electroplated or welded to an outer peripheral surface of the cylindrical base; a flow passage for circulating air in the axial direction of the shaft is formed inside the at least one grinding roll, The at least one grinding roll comprises an upper edge portion, a lower edge portion, a communication passage disposed between the upper edge portion and the lower edge portion and connecting the flow passage with the outside of the grinding roll, and at least one annular portion extending annularly from a position corresponding to the cylindrical base as viewed in the axial direction toward a radially inner side of the cylindrical base, the at least one annular portion being disposed adjacent to the communication passage. Grain milling machine.

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