Grinding wheel roll

Abstract

Provided is a grinding wheel roll capable of shortening rice milling time, improving the flow or the like of rice in a rice milling chamber, and preventing clogging of the grinding wheel roll, thereby improving productivity of rice milling.　A grinding wheel roll (1) is divided into a first stage (a) to a sixth stage (f) in the up-down direction of the vertical axis, and the first stage (a) to the sixth stage (f) are layered. An abrasive grain part (6) and non-abrasive grain parts (7) are formed on the outer circumferential surface (5a) of a fifth stage (e), and the plurality of non-abrasive grain parts (7) are provided at intervals along the circumferential direction of the grinding wheel roll (1).

Description

Grinding Roll

[0001] The present invention relates to a grinding roll housed in a rice milling chamber of a rice milling machine, and particularly to a grinding roll capable of efficient rice milling.

[0002] Conventionally, technologies related to rice milling machines equipped with grinding rolls have been developed for the purpose of efficiently performing spherical rice milling, original shape rice milling, and flat rice milling. However, in the prior art, the hardness of the abrasive grains attached to the grinding roll is weak, and the abrasive grains are quickly consumed, so it is necessary to frequently replace the grinding roll, and it may be difficult to realize a desired rice milling method or rice milling ratio. Also, if there is a difference between the action of drawing raw rice into the rice milling chamber and the action of discharging the milled rice, the flow and filling balance of the rice in the rice milling chamber will become poor, and due to the high viscosity of the red bran generated at the initial stage of rice milling, there is also a problem that the productivity of rice milling decreases due to clogging of the grinding roll. Therefore, technologies for solving such problems have been developed, and inventions related thereto have been disclosed.

[0003] Patent Document 1 discloses an invention related to a sake brewing rice milling machine that can realize a desired rice milling method and rice milling ratio under the name of "sake brewing rice milling machine". The pounding and grinding roll provided in the invention disclosed in Patent Document 1 is formed such that its rotation direction can be changed between the normal rotation direction and the reverse rotation direction, and a first superhard abrasive grain tip whose cutting edge acts in the normal rotation direction and a second superhard abrasive grain tip whose cutting edge acts in the reverse rotation direction are arranged and fixed in multiple rows. The first superhard abrasive grain tip has a coarse particle size, and the second superhard abrasive grain tip has a fine particle size. Therefore, according to the invention disclosed in Patent Document 1, even when the rice milling ratio is lowered, it is possible to finish with a plurality of rice milling methods without replacing the pounding and grinding roll.

[0004] Japanese Patent Application Laid-Open No. 2018-140369

[0005] However, because the first and second carbide abrasive chips are partially arranged in the circumferential direction of the grinding wheel roll, the area ratio of each abrasive grain to the entire grinding wheel roll is small. As a result, the number of abrasive grains that come into contact with the rice during milling is halved compared to conventional rice milling machines where abrasive grains of the same particle size are evenly arranged in the circumferential direction of the grinding wheel roll. Consequently, there was a problem in that the milling time doubled when trying to achieve the target milling rate. Furthermore, problems such as poor rice flow in the milling chamber and reduced productivity due to clogging of the grinding wheel roll could not be fully solved by the invention disclosed in Patent Document 1.

[0006] This invention addresses the aforementioned conventional circumstances and aims to provide a grinding wheel roll that can shorten the rice milling time, improve the flow of rice within the milling chamber, prevent clogging of the grinding wheel roll, and thereby improve the productivity of rice milling.

[0007] To achieve the above objective, the first invention provides an annular grinding wheel roll mounted on a vertical shaft located inside the rice milling chamber of a rice milling machine, and rotatable around the central axis of the vertical shaft, wherein the grinding wheel roll has an abrasive portion to which abrasive grains adhere and a non-abrasive portion to which abrasive grains do not adhere on its outer circumferential surface, and one or more non-abrasive portions are provided along the circumferential direction of the grinding wheel roll.

[0008] In this invention, the abrasive portion is formed by, for example, electroplating abrasive grains onto the outer surface of the base metal of the grinding wheel roll. In this case, the non-abrasive portion is the part where abrasive grains are not electroplated. Therefore, the surface of the non-abrasive portion is not flush with the surface of the abrasive portion, and a step is formed at the boundary between them. Furthermore, the shape of the non-abrasive portion can be linear, circular, polygonal, etc., and is not particularly limited. Moreover, the number of non-abrasive portions can be one or more, and is not particularly limited. When there are multiple non-abrasive portions, for example, they can be arranged at regular intervals along the circumferential direction of the grinding wheel roll.

[0009] In the invention described above, when rice comes into contact with the rotating grinding wheel roll, the rice collides with the step at the boundary between the non-abrasive portion and the abrasive portion. As a result, a force in the direction of pushing the rice is applied to the rice, increasing the speed at which the rice moves.

[0010] The second invention is characterized in that, in the first invention, the grinding wheel roll is divided into multiple stages in the axial direction of the vertical axis, and the multiple stages are stacked, and the non-abrasive portion is formed in at least one of the multiple stages. In the invention with this configuration, the type and size of the abrasive grains may differ or be the same for each of the multiple stages. In the invention with the above configuration, in addition to the effects of the first invention, the portion in which the movement speed of the rice in the rice milling chamber increases will differ depending on which stage of the grinding wheel roll the non-abrasive portion is formed. Also, by dividing the grinding wheel roll into multiple stages, the weight per stage becomes lighter.

[0011] The third invention is characterized in that, in the first or second invention, the non-abrasive portion is linear in shape, and its longitudinal direction is inclined with respect to the circumferential direction of the grinding wheel roll. In an invention with such a configuration, the shape of the non-abrasive portion is not particularly limited and can be straight, arc-shaped, etc. Furthermore, the inclination angle of the longitudinal direction of the non-abrasive portion with respect to the circumferential direction of the grinding wheel roll may be any value greater than 0 degrees and less than 180 degrees. Here, an inclination angle of 0 degrees and 180 degrees are concepts when the longitudinal direction of the non-abrasive portion is parallel to the circumferential direction of the grinding wheel roll. In an invention with the above configuration, in addition to the effects of the first or second invention, because the non-abrasive portion is linear, for example, the total number of grains that collide with the non-abrasive portion per rotation of the grinding wheel roll increases compared to when the non-abrasive portion is point-shaped, and the number of grains whose moving speed increases increases. Furthermore, the inclination angle of the non-abrasive section changes the length of the axial component of the grinding wheel roll in the non-abrasive section, which in turn changes the total number of grains of rice that collide with the non-abrasive section, as well as the direction of movement of the grains after they collide with the non-abrasive section.

[0012] The fourth invention is characterized in that, in the second invention, the grinding wheel roll is divided into at least an upper section and a lower section, and the non-abrasive section is formed in at least one of the upper section and the lower section. In this configuration, the upper section is positioned close to the input port for putting rice into the rice milling chamber, and the lower section is positioned close to the discharge port for discharging rice from the rice milling chamber. Therefore, in the invention with the above configuration, in addition to the effects of the second invention, when the non-abrasive section is formed in the upper section, the rate at which the rice put in from the input port is swallowed into the rice milling chamber is increased, and when the non-abrasive section is formed in the lower section, the rate at which the rice is discharged from the discharge port is increased.

[0013] The fifth invention is characterized in that, in the second invention, the grinding wheel roll is divided into at least an upper and a lower section, the abrasive grains in the upper section are first diamond abrasive grains or first cBN abrasive grains, and the abrasive grains in the lower section are second diamond abrasive grains or second cBN abrasive grains. In an invention with such a configuration, the first diamond abrasive grains in the upper section and the second diamond abrasive grains in the lower section may be the same or different in terms of factors that affect the grinding ability, such as the shape and grit size of the diamond abrasive grains. Similarly, the first cBN abrasive grains in the upper section and the second cBN abrasive grains in the lower section may be the same or different in terms of factors that affect the grinding ability of the cBN abrasive grains. Furthermore, diamond abrasive grains and cBN abrasive grains are each best suited to different stages of rice milling. By using these as abrasive grains, the characteristics of the resulting bran change appropriately throughout the process, from red bran in the early stages of milling, to medium bran in the middle stages, and finally to white bran in the later stages.

[0014] Therefore, in the invention with the above configuration, in addition to the effects of the second invention, by selecting and combining the types of abrasive grains in the upper and lower sections from diamond abrasive grains and cBN abrasive grains, respectively, the effects of preventing clogging of the grinding wheel roll by red rice bran, high grinding action for red rice bran, medium rice bran, and white rice bran, and promoting rice movement are simultaneously achieved.

[0015] The sixth invention is characterized in that, in the second invention, the grinding wheel roll is divided into an upper, middle, and lower section, and the upper section grain size (grain size of the abrasive grains in the upper section) and the lower section grain size (grain size of the abrasive grains in the lower section) are the same as or coarser than the middle section grain size (grain size of the abrasive grains in the middle section). In an invention with such a configuration, the upper section mainly affects the speed at which the rice is swallowed, the middle section mainly affects the shape of the rice after milling, and the lower section mainly affects the speed at which the rice is fed out. Furthermore, grain size is an index that indicates the size (roughness) of the abrasive grains, and the coarser the grain size, the higher the grinding ability and the greater the effect of promoting the movement of the rice. In addition, grain size is a factor that affects the shape of the milled rice (spherical, original shape, flattened), with coarser grain size making it easier to form spherical milled rice, fine grain size making it easier to form flattened milled rice, and intermediate grain size making it easier to form original shape milled rice.

[0016] Therefore, in the invention with the above configuration, in addition to the effects of the second invention, the upper and lower grain sizes are the same as or coarser than the middle grain size, respectively, thereby increasing the rice swallowing speed, feeding speed, and grinding ability in the upper and lower stages, while forming milled rice of the desired shape in the middle stage.

[0017] According to the first invention, the formation of abrasive and non-abrasive portions on the outer surface of the grinding wheel roll increases the movement speed of the rice, thereby improving the flow and filling balance of the rice in the rice milling chamber. As a result, clogging of the abrasive portion is prevented.

[0018] According to the second invention, in addition to the effects of the first invention, the area where the movement speed of rice in the rice milling chamber increases will differ depending on which stage of the grinding wheel roll the non-abrasive portion is formed on. Therefore, by providing the non-abrasive portion in areas where rice tends to accumulate or where clogging of the grinding wheel roll is likely to occur, the poor rice milling efficiency in these areas can be eliminated. Furthermore, since the grinding wheel roll is divided into multiple stages, the weight of each stage is reduced, making it easier to replace only the worn-out stages, for example, thereby reducing the workload and replacement costs.

[0019] According to the third invention, in addition to the effects of the first or second invention, the non-abrasive portion being linear increases the proportion of rice whose movement speed increases within the milling chamber, thus shortening the milling time. Therefore, the productivity of milling is improved. Furthermore, the direction of movement of the rice after it collides with the non-abrasive portion changes depending on the inclination angle of the non-abrasive portion, so the direction in which the rice flows can be adjusted. Therefore, according to the third invention, the length of the milling time can be adjusted.

[0020] According to the fourth invention, in addition to the effects of the second or third invention, when the non-abrasive portion is formed in the upper section, the rice feeding speed is increased, and when the non-abrasive portion is formed in the lower section, the rice dispensing speed is increased. For example, the feeding speed and the dispensing speed can be increased while remaining equivalent. This prevents the rice from accumulating in the rice milling chamber, resulting in improved rice milling productivity.

[0021] According to the fifth invention, in addition to the effects of the second or third invention, the combination of diamond abrasive grains and cBN abrasive grains simultaneously provides an anti-clogging effect on the grinding wheel roll, a high grinding effect on all of the red bran, medium bran, and white bran, and an effect that promotes the movement of the rice, making it possible to achieve the desired rice milling method in a short time.

[0022] According to the sixth invention, in addition to the effects of the second or third invention, the rice swallowing speed, feeding speed, and grinding ability are increased in the upper and lower stages, while the desired shape of milled rice is formed in the middle stage, thus shortening the milling time until the desired rice shape is achieved. Therefore, the sixth invention is particularly suitable for milling rice for sake brewing.

[0023] This is a longitudinal cross-sectional view of the grinding wheel roll according to Example 1. This is a perspective view showing the external appearance of the grinding wheel roll according to Example 1. This is a side view showing the external appearance of the grinding wheel roll according to Example 1. This is a side view showing the external appearance of the grinding wheel roll according to Example 1. This is a configuration table of the grinding wheel rolls according to Examples 1 to 6. This is a side view showing the external appearance of the grinding wheel roll according to Example 3.

[0024] A grinding wheel roll according to an embodiment of the present invention will be described in detail with reference to Figures 1 to 6. Figure 1 is a longitudinal cross-sectional view of a grinding wheel roll according to Embodiment 1. As shown in Figure 1, the grinding wheel roll 1 according to Embodiment 1 is mounted on a vertical shaft 23 provided inside the rice milling chamber 22, which is formed by the rice milling cylinder 21 of the rice milling machine 20, and the central axis A of this vertical shaft 23 ２３ It is a circular grinding wheel roll that can rotate around the periphery. The grinding wheel roll 1 is divided into an upper section 2, a middle section 3, and a lower section 4 with respect to the axial direction Y of the vertical shaft 23, and these upper sections 2 to lower section 4 are stacked on top of each other. In detail, the upper sections 2 to lower section 4 are each roughly donut-shaped.

[0025] The upper section 2 is divided into the first section a and the second section b, and the middle section 3 is divided into the third section c and the fourth section d. The lower section 4 is divided into the fifth section e and the sixth section f. Of these, the first section a, the third section c, and the fifth section e all have a mountain-like shape on the upper part of their outer circumferential surface, which adjusts the flow velocity and pressure of the rice. Furthermore, the first section a to the fourth section d and the sixth section f of the grinding wheel roll 1 have abrasive sections formed on their entire outer circumferential surface where abrasive grains are attached. In contrast, the fifth section e of the grinding wheel roll 1 has an abrasive section on its outer circumferential surface where abrasive grains are attached and a non-abrasive section where abrasive grains are not attached. Specifically, the type of abrasive grain in the abrasive section is cBN (cubic boron nitride) for the first section a to the fourth section d, and diamond for the fifth section e and the sixth section f. The configuration of the abrasive grain portion and the non-abrasive grain portion will be explained using Figures 2 to 4.

[0026] Next, the upper grit size, which is the grit size of the abrasive grains in the first stage a and the second stage b, and the lower grit size, which is the grit size in the fifth stage e and the sixth stage f, are the same as or coarser than the middle grit size, which is the grit size in the third stage c and the fourth stage d. For example, in grinding wheel roll 1, the upper grit size and the lower grit size are medium (#60, # is the abrasive grain number, the same applies below), and the middle grit size is also medium (#60). However, when the upper grit size and the lower grit size are medium (#60), the middle grit size may be fine (#80), and when the upper grit size and the lower grit size are coarse (#40), the middle grit size may be medium (#60) or fine (#80). In addition, if the upper and lower grit sizes are fine (#80), the middle grit size may also be fine (#80).

[0027] The rice milling chamber 22 is equipped with a supply port 24 at its upper end for supplying raw rice to the rice milling chamber 22, a swallowing section 25 for swallowing the supplied raw rice, and a discharge section 26 for discharging the milled raw rice. The swallowing section 25 is the space formed between the first stage a and the rice milling cylinder 21, and the discharge section 26 is the space formed between the sixth stage f and the rice milling cylinder 21.

[0028] Next, the configuration of the abrasive portion and non-abrasive portion of the grinding wheel roll 1 will be explained using Figures 2 to 4 and 5. Figure 2 is a perspective view showing the external appearance of the grinding wheel roll according to Embodiment 1. Figure 3 is a side view showing the external appearance of the grinding wheel roll according to Embodiment 1. Figure 4 is a side view showing the external appearance of the grinding wheel roll according to Embodiment 1. Figure 5 is a configuration table of the grinding wheel rolls according to Embodiments 1 to 6. Note that the same reference numerals are used for the components shown in Figure 1 in Figures 2 to 4, and their explanations are omitted. As shown in Figures 2 and 3, the fifth stage e of the lower stage 4 has an abrasive portion 6 on its outer circumferential surface 5a to which abrasive grains are attached, and a non-abrasive portion 7 to which abrasive grains are not attached. Of these, the abrasive portion 6 is formed by electrodepositing abrasive grains onto the base metal 5b that constitutes the fifth stage e. Therefore, the non-abrasive portion 7 is the part of the base metal 5b to which abrasive grains are not electrodeposited. The rotation direction R of the fifth stage e is the direction in which the upper end 7a of the non-abrasive portion 7 is the leading edge of the rotation.

[0029] Furthermore, multiple non-abrasive sections 7 are provided at equal intervals along the circumferential direction X of the fifth stage e. In detail, as shown in Figure 3, the non-abrasive section 7 has a linear groove structure, and its longitudinal direction L is inclined at an angle θ with respect to the circumferential direction X of the fifth stage e. This angle θ is set so that the upper end 7a of the non-abrasive section 7 rises up at approximately 20 degrees counterclockwise with respect to the circumferential direction X of the fifth stage e. Furthermore, the length L of the non-abrasive section 7 in the longitudinal direction L is also specified. ７ The width is approximately 50 mm, and the width W is in the direction perpendicular to the longitudinal direction L. ７ It is approximately 3 mm. However, the number of non-abrasive parts 7, the inclination angle θ, and the length L are not specified. ７ , width W ７The above may be incorrect. As mentioned above, the lower section 4 is roughly donut-shaped, so in the fifth section e, the opposing surface 5c that is closest to and facing the rice milling cylinder 21 (see Figure 1) is formed on approximately the lower half of the outer peripheral surface 5a. Furthermore, since the non-abrasive parts 7 are arranged on the opposing surface 5c, the non-abrasive parts 7 can capture the rice flowing between the rice milling cylinder 21 and the opposing surface 5c and efficiently feed it out.

[0030] Furthermore, as shown in Figure 4, since the non-abrasive portion 7 is formed only on the fifth stage e of the grinding wheel roll 1, the feed speed of the rice that has reached the fifth stage e from the feeding portion 25 (see Figure 1) increases above the discharge portion 26 (see Figure 1). In addition, since the longitudinal direction L of the non-abrasive portion 7 is inclined at an angle θ with respect to the circumferential direction X of the fifth stage e, the direction of movement of the rice after it collides with the non-abrasive portion 7 changes to approach the downward direction perpendicular to the longitudinal direction L. In other words, the rice is fed towards the discharge portion 26.

[0031] In the grinding wheel roll 1 according to Embodiment 1 of the above configuration, the first stage a to the fourth stage d are cBN abrasive grains, and the fifth stage e and the sixth stage f are diamond abrasive grains. Therefore, the first stage a to the fourth stage d have high grinding capacity for medium bran and white bran, and the fifth stage e and the sixth stage f have high grinding capacity for red bran. In addition, since the fifth stage e is provided with a non-abrasive section 7, the effect of feeding rice to the discharge section 26 is high. Therefore, the grinding wheel roll 1 makes it possible to improve the flow and filling balance of rice in the rice milling chamber 22. Furthermore, since the non-abrasive section 7 is linear, the proportion of rice whose moving speed increases in the rice milling chamber 22 increases, so the milling time can be shortened and the productivity of rice milling is high. In addition, the upper, middle, and lower grain sizes of the grinding wheel roll 1 are all medium. That is, in particular, the middle grain size of the middle stage 3 is medium, so it is easy to form the original shape of milled rice.

[0032] Next, the configurations of the grinding wheel rolls 1A to E according to Examples 2 to 6 will be explained using Figures 5 and 6. Figure 5 is a configuration table of the grinding wheel rolls according to Examples 1 to 6. Figure 6 is a side view showing the external appearance of the grinding wheel roll according to Example 3. The grit sizes of the abrasive grains shown in Figure 5 are coarse (#40) for the 5th stage of grinding wheel roll 1C in Example 4 and the 6th stage of grinding wheel roll 1E in Example 6, and medium (#60) for all others. Furthermore, the same reference numerals are used for the components shown in Figures 1 to 4 in Figure 6, and their explanations are omitted.

[0033] As shown in Figure 5, the configuration of the grinding wheel roll 1A according to Embodiment 2 is such that the abrasive grains in the first stage a are diamond abrasive grains, and the abrasive grains in the second stage b to the sixth stage f are cBN abrasive grains. In addition, a non-abrasive section 7 is provided in the fifth stage e. Furthermore, since the upper, middle, and lower grit sizes of the grinding wheel roll 1A are all medium, the grinding wheel roll 1B, like the grinding wheel roll 1, is particularly good at forming original-shaped milled rice. Therefore, with the grinding wheel roll 1A, the clogging prevention effect by red bran, the high grinding effect on red bran, medium bran, and white bran, and the rice feeding effect to the discharge section 26 are all exhibited simultaneously, making it possible to realize the desired rice milling method in a short time.

[0034] In the configuration of the grinding wheel roll 1B according to Example 3, the abrasive grains in the first stage a to the sixth stage f are all cBN abrasive grains, and the upper, middle, and lower stage grit sizes are all medium. Therefore, in the grinding wheel roll 1C, as with the grinding wheel roll 1, it is particularly easy to form original-shaped polished rice. Also, as shown in Figure 6, the first stage a, third stage c, and fifth stage e of the grinding wheel roll 1B are each provided with multiple non-abrasive sections 7. The number of these non-abrasive sections 7, the inclination angle θ, and the length L ７ , width W ７ (See Figure 3) is the same as that of the fifth stage e of the grinding wheel roll 1 in Example 1. Furthermore, the non-abrasive portion 7 is also arranged in the first stage a and the third stage c so as to be closest to the rice milling cylinder 21 (see Figure 1), as shown on the opposing surface 5c of the fifth stage e (see Figure 3). Therefore, the non-abrasive portion 7 can capture the rice flowing between the rice milling cylinder 21, the first stage a, the third stage c, and the fifth stage e, and efficiently feed it out.

[0035] Therefore, when rice supplied from the supply port 24 (see Figure 1) collides with the first stage a, it then collides with the third stage c and the fifth stage e of the grinding wheel roll 1B. As a result, the rice is pushed towards the second stage b, the third stage, and the discharge section 26 by the multiple non-abrasive sections 7. Thus, although the abrasive grains in the first stage a, the third stage c, and the fifth stage e of the grinding wheel roll 1B are not diamond, the rice feeding action is high. Furthermore, the first stage a and the fifth stage e allow the rice to be consumed at the consuming section 25 and fed to the consuming section 25 to be increased while remaining equal, thus preventing rice from accumulating in the rice milling chamber 22 and increasing the productivity of rice milling.

[0036] In the grinding wheel roll 1C according to Example 4, the abrasive grains in the first stage a to the sixth stage f are cBN abrasive grains. Furthermore, the abrasive grains in the first stage a to the fourth stage d and the sixth stage f are medium grit (#60), while the abrasive grains in the fifth stage e are coarse grit (#40). Therefore, the grinding capacity is high in the fifth stage e.

[0037] In the grinding wheel roll 1D according to Example 5, the abrasive grains in the first stage a to the sixth stage f are all medium-grit (#60) cBN abrasive grains. In addition, a non-abrasive section 7 is formed in the fifth stage e. Therefore, the rice feeding speed to the discharge section 26 is increased in the fifth stage e, which shortens the milling time until the original milled rice is formed and reduces clogging of the abrasive section 6.

[0038] In the grinding wheel roll 1E according to Example 6, the abrasive grains in the first stage a are medium-grit (#60) diamond abrasive grains. The abrasive grains in the second stage b to the fifth stage e are all medium-grit (#60) cBN abrasive grains, and the abrasive grains in the sixth stage f are coarse-grit (#40) cBN abrasive grains. Furthermore, a non-abrasive section 7 is formed in the fifth stage e. Therefore, in the first stage a, the rice is fed into the feeding section 25 at a high rate and the grinding capacity is high. Also, in the fifth stage e and the sixth stage f, the rice is fed into the discharge section 26 at a high rate, so the milling time until the original milled rice is formed can be shortened and productivity can be improved.

[0039] It should be noted that the grinding wheel roll according to the present invention is not limited to those shown in the examples. For example, in the grinding wheel roll 1, the non-abrasive portion 7 may be formed only in the first stage a, only in the third stage c, or in the first stage a and the third stage c, instead of the fifth stage e. Also, the middle stage 3 of the grinding wheel roll 1 may be omitted and divided into only the upper stage 2 and the lower stage 4. Furthermore, the abrasive grains of the first stage a and the sixth stage f may both be diamond abrasive grains. In addition, in the grinding wheel roll 1B according to Example 3, the third stage c may not have a non-abrasive portion 7 formed on its outer circumferential surface, and may only have an abrasive portion 6 attached to it, similar to that of the fourth stage d.

[0040] This invention can be used as a grinding wheel roll housed in the rice milling chamber of a rice milling machine.

[0041] 1, 1A, 1B, 1C, 1D, 1E... Grindstone roll 2... Upper stage 3... Middle stage 4... Lower stage a... 1st stage b... 2nd stage c... 3rd stage d... 4th stage e... 5th stage f... 6th stage 5a... Outer peripheral surface 5b... Base metal 5c... Opposing surface 6... Abrasive part 7... Non-abrasive part 7a... Upper end 20...Rice polishing machine 21...Rice polishing cylinder 22...Rice milling chamber 23...Vertical shaft 24...Supply port 25...Swallowing part 26...Discharge part

Claims

1. An annular grinding wheel roll mounted on a vertical shaft located inside the rice milling chamber of a rice milling machine, and rotatable around the central axis of the vertical shaft, wherein the grinding wheel roll has an abrasive portion to which abrasive grains are attached and a non-abrasive portion to which abrasive grains are not attached on its outer circumferential surface, and one or more non-abrasive portions are provided along the circumferential direction of the grinding wheel roll.

2. The grinding wheel roll according to claim 1, wherein the grinding wheel roll is divided into a plurality of steps in the axial direction of the vertical shaft, and the plurality of steps are stacked, and the non-abrasive portion is formed in at least one of the plurality of steps.

3. The abrasive roll according to claim 1 or 2, characterized in that the non-abrasive portion is linear in shape and its longitudinal direction is inclined with respect to the circumferential direction of the abrasive roll.

4. The grinding wheel roll according to claim 2, wherein the grinding wheel roll is divided into at least an upper section and a lower section, and the non-abrasive portion is formed in at least one of the upper section and the lower section.

5. The grinding wheel roll according to claim 2, wherein the grinding wheel roll is divided into at least an upper section and a lower section, the abrasive grains in the upper section are first diamond abrasive grains or first cBN abrasive grains, and the abrasive grains in the lower section are second diamond abrasive grains or second cBN abrasive grains.

6. The grinding wheel roll according to claim 2, wherein the grinding wheel roll is divided into an upper section, a middle section, and a lower section, and the upper section grit size, which is the grit size of the abrasive grains in the upper section, and the lower section grit size, which is the grit size of the abrasive grains in the lower section, are the same as or coarser than the middle section grit size, which is the grit size of the middle section.

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