Barrel polishing equipment

Abstract

To improve polishing efficiency.SOLUTION: A barrel polishing device comprises: a rotatable barrel tank 10; a polishing material 14 which is stored in the barrel tank 10 and moves in the peripheral direction following rotation of the barrel tank 10; a support member 16 which rotatably supports a workpiece 19 in a state of being immersed in the polishing material 14; and lateral restriction plates 22, 23 which are arranged so as to be arranged with a gap in the radial direction of the barrel tank 10 with respect to the workpiece 19. In the movement direction of the polishing material 14, upstream ends 22A, 23A of the lateral restriction plates 22, 23 are arranged at the same position as the rotation center 19R of the workpiece 19 or the gravity center 19G of the workpiece 19 or the position on the downstream side with respect to the rotation center 19R or the gravity center 19G.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a barrel polishing machine. [Background technology]

[0002] Patent Document 1 discloses a barrel polishing machine in which polishing media are stored in a rotating polishing media storage tank, and a pair of auxiliary plates and a workpiece are placed inside the polishing media storage tank. The polishing media move circumferentially as the polishing media storage tank rotates. The pair of auxiliary plates are arranged to sandwich the workpiece in the radial direction of the polishing media storage tank. The polishing media is pressed against the workpiece by the pair of auxiliary plates while moving between the pair of auxiliary plates relative to the workpiece. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-71165 Summary of the Invention [Problem to be solved by the invention]

[0004] In the direction of movement of the polishing medium, the upstream ends of the pair of auxiliary plates are located upstream of the upstream end of the workpiece. The polishing medium that flows between the pair of auxiliary plates concentrates in the gap between the workpiece and the auxiliary plates, which is narrower than the gap between the pair of auxiliary plates, causing a jam. This reduces the movement speed of the polishing medium that comes into contact with the workpiece, and reduces the polishing efficiency.

[0005] The present invention was completed in view of the above circumstances, and an object of the present invention is to improve polishing efficiency. [Means for solving the problem]

[0006] The first invention is A rotatable barrel tank; an abrasive material accommodated in the barrel tank and moving in a circumferential direction as the barrel tank rotates; a support member that rotatably supports a workpiece while immersed in the abrasive; and side restraint plates arranged to be spaced apart from each other in the radial direction of the barrel tank relative to the workpiece, The upstream end of the lateral restraint plate is positioned at the same position as the center of rotation or the center of gravity of the workpiece in the direction of movement of the abrasive material, or at a position downstream of the center of rotation or the center of gravity of the workpiece.

[0007] The second invention is: A rotatable barrel tank; an abrasive material accommodated in the barrel tank and moving in a circumferential direction as the barrel tank rotates; a support member that supports the workpiece while immersed in the abrasive; and side restraint plates arranged to be spaced apart from each other in the radial direction of the barrel tank relative to the workpiece, The distance between the side restraint plates and the workpiece is smallest at the upstream end of the side restraint plates in the moving direction of the abrasive material. [Effects of the Invention]

[0008] According to the first and second inventions, the abrasive material heading toward the gap between the lateral restraint plate and the workpiece is less likely to become congested, and the decrease in the movement speed of the abrasive material coming into contact with the workpiece is suppressed, thereby improving the abrasive efficiency. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view of a barrel polishing machine according to a first embodiment. [Figure 2] FIG. 2 is a plan view of the barrel polishing machine. [Figure 3] 3 is a partially enlarged view of the restraining member and the supporting member of the first embodiment, viewed in the direction in which the abrasive passes. FIG. [Figure 4] 4 is a cross-sectional plan view taken along line XX in FIG. 3, showing a restraining form of the first embodiment. FIG. [Figure 5]FIG. 7 is a cross-sectional plan view corresponding to line XX showing a restraining form of the second embodiment. [Figure 6] FIG. 2 is a cross-sectional plan view corresponding to line XX showing a restraining form of comparative form 1. [Figure 7] FIG. 2 is a cross-sectional plan view corresponding to line XX showing a restraining form of comparative form 2. [Figure 8] FIG. 2 is a cross-sectional plan view corresponding to line XX showing a restraining form of comparative form 3. [Figure 9] FIG. 2 is a cross-sectional plan view corresponding to line XX showing a restraining form of comparative form 4. DETAILED DESCRIPTION OF THE INVENTION

[0010] In the barrel polishing machine of the first invention, the upstream ends of the side restraint plates are located at the same position as the center of rotation or center of gravity of the workpiece, or downstream of the center of rotation or center of gravity, in the direction of movement of the abrasive, so there are no side restraint plates upstream of the center of rotation or center of gravity of the workpiece. Of the abrasives heading toward the gap between the side restraint plates and the workpiece, some of the abrasives moving in the area upstream of the center of rotation or center of gravity of the workpiece can escape in a direction away from the workpiece. Therefore, the abrasives heading toward the gap between the side restraint plates and the workpiece are less likely to become congested, and a decrease in the movement speed of the abrasives contacting the workpiece is suppressed, improving polishing efficiency.

[0011] In the barrel polishing machine of the second invention, the distance between the side restraint plates and the workpiece is smallest at the upstream end of the side restraint plates in the direction of movement of the abrasive, so there are no side restraint plates upstream of the position where the distance between the side restraint plates and the workpiece is smallest. Of the abrasive heading toward the gap between the side restraint plates and the workpiece, some of the abrasive moving in the area upstream of the position where the distance between the side restraint plates and the workpiece is smallest can escape in a direction away from the workpiece. Therefore, the abrasive heading toward the gap between the side restraint plates and the workpiece is less likely to become congested, and a decrease in the movement speed of the abrasive coming into contact with the workpiece is suppressed, thereby improving polishing efficiency.

[0012] In the first and second inventions, it is preferable that the workpieces are placed only in an area away from the rotation axis of the barrel tank, and the pair of side restraint plates are placed at a position close to the rotation axis with respect to the workpieces and a position far from the rotation axis with respect to the workpieces. With this configuration, the pair of side restraint plates can efficiently polish the workpieces.

[0013] In the first and second aspects of the present invention, it is preferable to provide an upper restraint plate that is immersed in the abrasive and covers the workpiece from above. With this configuration, even if the workpiece is placed in an upper layer region of the abrasive, the abrasive can be pressed against the upper surface of the workpiece, thereby increasing the abrasive force.

[0014] In the first and second aspects of the present invention, it is preferable that the upstream end of the upper restraint plate is located upstream of the upstream ends of the side restraint plates in the direction of movement of the abrasive material. This configuration allows for good polishing of the top and side surfaces of the workpiece.

[0015] Example 1 A first embodiment of the present invention will be described below with reference to Figures 1 to 9. As shown in Figures 1 and 2, the barrel polishing machine of this first embodiment is a polishing machine known as a gyro polisher, and includes a barrel tank 10, a plurality of polishing materials 14, a support member 16, and a restraining member 20. In the following description, the up and down directions will be defined as those shown in Figures 1 and 3.

[0016] The barrel tank 10 is a cylindrical container with a bottom that has a circular shape in a plan view from above and is open to the entire top surface. The barrel tank 10 has a bottom wall portion 11 and a peripheral wall portion 12 that rises from the outer periphery of the bottom wall portion 11. The bottom wall portion 11 of the barrel tank 10 is fixed concentrically to a vertical rotation shaft 13 driven by a motor (not shown). The barrel tank 10 is driven to rotate in a clockwise or counterclockwise direction in a plan view.

[0017] The abrasive 14 is contained in the barrel tank 10. When the barrel tank 10 rotates, the abrasive 14 moves circumferentially together with the barrel tank 10. In addition to the abrasive 14, water (not shown) and a compound (not shown) are also contained in the barrel tank 10. The abrasive 14, water, and compound introduced into the barrel tank 10 form a polishing layer 15 that comes into contact with a workpiece 19 to polish the workpiece 19. The workpiece 19 is a spur gear with a circular tooth tip circle.

[0018] In plan view, the support member 16 is located inside the peripheral wall portion 12 of the barrel tank 10 and eccentric in the radial direction R from the rotation axis 13 of the barrel tank 10. The support member 16 has a fixed pipe-shaped bearing member 17 and a support shaft 18 inserted into the bearing member 17 parallel to the rotation axis 13. The support shaft 18 is driven to rotate clockwise or counterclockwise in plan view. The lower ends of the support shaft 18 and the bearing member 17 are immersed in the polishing layer 15 (abrasive 14). The lower end of the support shaft 18 protrudes downward beyond the lower end of the bearing member 17. A workpiece 19 is fixed to the lower end of the support shaft 18 so that they can rotate concentrically together. In this Example 1, the axis of the support shaft 18 is defined as the "rotation center 19R of the workpiece 19." The direction connecting the rotation axis 13 of the barrel tank 10 and the rotation center 19R of the workpiece 19 is defined as the "radial direction R" (see FIG. 4).

[0019] The restraint member 20 has one upper restraint plate 21 and a pair of side restraint plates 22, 23. The upper restraint plate 21 is a flat member having a rectangular shape in a plan view. The upper restraint plate 21 is fixed to the lower end of the bearing member 17 in a horizontal direction perpendicular to the rotation shaft 13. In a plan view, the short side 21S of the upper restraint plate 21 is parallel or approximately parallel to the radial direction R, and the long side 21L of the upper restraint plate 21 is perpendicular or approximately perpendicular to the radial direction R. The upper restraint plate 21 is arranged so as to be immersed in the polishing layer 15 (the abrasive 14).

[0020] When the upper restraint plate 21 is not positioned above the workpiece 19 and the workpiece 19 is positioned in a lower region of the polishing layer 15, the total weight of the abrasive 14 moving above the workpiece 19 is large, so a certain degree of pressing force acts from the abrasive 14 on the workpiece 19, resulting in a relatively large polishing force. In contrast, when the workpiece 19 is positioned in an upper region (surface region) of the polishing layer 15, the abrasive 14 rises up as if to escape from the workpiece 19, so the pressing force of the abrasive 14 on the workpiece 19 decreases, and a high polishing force cannot be obtained. When the upper restraint plate 21 is positioned above the workpiece 19, the downward pressing force from the abrasive 14 on the workpiece 19 increases as the workpiece 19 passes through the gap between the upper restraint plate 21 and the workpiece 19. This downward pressing force increases the polishing force on the top surface of the workpiece 19. Furthermore, between the workpiece 19 and the side restraint plates 22, 23, the presence of the upper restraint plate 21 prevents the abrasive 14 from escaping upward, increasing the pressing force from the abrasive 14 to the workpiece 19 and increasing the abrasive force on the side (outer peripheral surface) of the workpiece 19.

[0021] The side restraint plates 22, 23 are rectangular, flat-plate-shaped members. The upper ends of the pair of side restraint plates 22, 23 are fixed to the long side 21L of the upper restraint plate 21. In this embodiment 1, two types of side restraint plates 22, 23 with different sizes are selectively used. The difference between the two types of side restraint plates 22, 23 is their lengths in the circumferential direction (the direction in which the abrasive 14 moves relative to the workpiece 19) in a plan view. The pair of side restraint plates 22, 23 are arranged in positions that sandwich the workpiece 19 in the radial direction R in a plan view. That is, one of the pair of side restraint plates 22, 23 is arranged at an inner position closer to the rotation shaft 13 than the workpiece 19, and the other side restraint plate 22, 23 is arranged at an outer position closer to the peripheral wall portion 12 than the workpiece 19. The pair of side restraint plates 22, 23 are arranged in a state where they are immersed in the abrasive layer 15 (in the abrasive 14).

[0022] The abrasive 14, which moves in the circumferential direction as the barrel tank 10 rotates, passes between the inner circumferential side restraint plates 22, 23 and the workpiece 19, and between the outer circumferential side restraint plates 22, 23 and the workpiece 19. The abrasive 14 polishes the outer surface of the workpiece 19 by contacting the workpiece 19 before, during, and after passing between the side restraint plates 22, 23 and the workpiece 19. In this Example 1, the direction perpendicular to the radial direction R in a plan view is defined as the "passing direction T of the abrasive 14" (see FIG. 4). The side restraint plates 22, 23 are arranged parallel to the passing direction T of the abrasive 14.

[0023] The polishing force exerted by the abrasive 14 on the workpiece 19 is stronger the faster the moving speed of the abrasive 14 is, and the stronger the pressing force of the abrasive 14 against the workpiece 19 is. The stronger the polishing force, the higher the polishing efficiency and the shorter the polishing time. When the abrasive 14 passes between the workpiece 19 and the side restraint plates 22, 23, the abrasive 14 concentrates in the gap, increasing the pressing force of the abrasive 14 against the workpiece 19, and therefore an improvement in the polishing force can be expected. When the abrasive 14 passes through the gap between the upper restraint plate 21 and the workpiece 19, the pressing force from the abrasive 14 to the workpiece 19 also increases, as with the side restraint plates 22, 23. Meanwhile, the movement path of the abrasive 14 suddenly narrows in the passage region where the workpiece 19 and the side restraint plates 22, 23 are aligned in the radial direction R. Therefore, the flow of the abrasive 14 is obstructed between the workpiece 19 and the side restraint plates 22, 23, which may reduce the moving speed of the abrasive 14 and reduce the abrasive force.

[0024] <Evaluation of polishing efficiency> The barrel polishing machine of Example 1 achieves improved polishing power (polishing efficiency) by optimizing the size of the side restraint plates 22, 23 in the movement direction of the abrasive 14 and the positional relationship between the workpiece 19 and the side restraint plates 22, 23. The inventors of the present application conducted experiments to evaluate the polishing efficiency by setting multiple restraint configurations with different sizes and locations of the side restraint plates 22-25. In Table 1 showing the experimental results, Example 1 and Example 2 are restraint configurations of Example 1 that achieved improved polishing efficiency. Comparative Examples 1-4 are restraint configurations with lower polishing efficiency than Example 1 and Example 2.

[0025] The experimental conditions common to Embodiments 1 and 2 and Comparative Examples 1 to 4 are as follows: The inner diameter of the barrel tank 10 is 800 mm, and the depth of the barrel tank 10 is 400 mm. The rotation speed of the barrel tank 10 is 30 rpm. The abrasives 14 are amorphous ceramic media. 85% of the abrasives 14 have a minor axis of 1.3 mm and a major axis of 3.4 mm. The relative movement speed of the abrasive layer 15 (abrasives 14) with respect to the workpiece 19 is proportional to the rotation speed of the barrel tank 10. Diluted water (not shown) containing 1% compound was introduced into the barrel tank 10 as a coolant liquid that constitutes the abrasive layer 15 together with the abrasives 14. The coolant liquid was supplied at a rate of 4 L / min. When the barrel tank 10 was stopped from rotating, the height from the bottom wall 11 to the top surface of the abrasive layer 15 was 200 mm.

[0026] In plan view, the position of the axis of the support shaft 18 is 280 mm eccentric from the rotation shaft 13 in the radial direction R. The workpiece 19 is a spur gear with a tooth tip circle diameter of φ50 mm and a face width of 20 mm. The workpiece 19 is fixed coaxially to the lower end of the support shaft 18. In plan view, the position of the support shaft 18 (rotation center 19R of the workpiece 19) and the position of the center of gravity 19G of the workpiece 19 are in the same position. The rotation speed of the workpiece 19 is 5 rpm. When the barrel tank 10 is stopped rotating, the upper surface of the workpiece 19 is located 25 mm below the upper surface of the polishing layer 15.

[0027] During polishing, when the barrel tank 10 was rotated clockwise, the workpiece 19 was rotated counterclockwise. When the barrel tank 10 was rotated counterclockwise, the workpiece 19 was rotated clockwise. The rotation directions of the barrel tank 10 and the workpiece 19 were switched every 2 minutes and 30 seconds. The surface roughness of the workpiece 19 was measured every 5 minutes of polishing time. The total time required for polishing was 20 minutes, and the surface roughness was measured four times.

[0028] The polishing efficiency was evaluated based on the "surface roughness change width" defined in Example 1. The surface roughness change width is the average value obtained by subtracting the "surface roughness after polishing" from the "surface roughness before polishing" over 5 minutes of polishing. Specifically, the surface roughness change width was measured at a total of 12 locations, including six locations on the tip of one tooth and six locations on the tip of the tooth located 180° opposite to that tooth, and the average value of these surface roughness change widths was used to evaluate the polishing efficiency of each embodiment and each comparative example.

[0029] 3 and 4, the first embodiment is a constraining configuration that includes an upper constraining plate 21 and a pair of side constraining plates 22. The upper constraining plate 21 is a rectangular flat plate with a long side 21L of 120 mm and a short side 21S of 80 mm. The distance between the lower surface of the upper constraining plate 21 and the upper surface of the workpiece 19 is 10 mm. In a plan view, the long side 21L of the upper constraining plate 21 is parallel or approximately parallel to the passage direction T of the abrasive 14, and the short side 21S of the upper constraining plate 21 is parallel or approximately parallel to the radial direction R. In the passage direction T of the abrasive 14, the upstream end 21A of the upper constraining plate 21 is located 60 mm upstream of the rotation center 19R of the workpiece 19, and the downstream end 21B of the upper constraining plate 21 is located 60 mm downstream of the rotation center 19R of the workpiece 19.

[0030] The pair of side restraint plates 22 are fixed to the outer surface of the upper restraint plate 21 on the long side 21L side, and extend parallel to each other in a cantilevered manner downward from the upper restraint plate 21. In a plan view, the pair of side restraint plates 22 are arranged parallel or approximately parallel to the passing direction T of the abrasive 14. In a passing direction view (see FIG. 3) viewed parallel or approximately parallel to the passing direction T of the abrasive 14, the pair of side restraint plates 22 are parallel to the rotation axis 13 of the barrel tank 10 and the rotation center 19R (support shaft 18) of the workpiece 19. In a view in the passing direction of the abrasive 14, the distance in the radial direction R between the tip circle of the workpiece 19 and the side restraint plates 22 is 15 mm.

[0031] The side restraint plates 22 used in the first embodiment are flat plates with a length of 40 mm in the passing direction T of the abrasive 14. As shown in FIG. 4, the downstream ends 22B of the pair of side restraint plates 22 are located at the same position as the downstream end 21B of the upper restraint plate 21. The upstream ends 22A of the pair of side restraint plates 22 are located 20 mm downstream of the rotation center 19R of the workpiece 19 and 45 mm downstream of the upstream end 19A of the workpiece 19. In a plan view, the distance between the side restraint plates 22 and the tip circle of the workpiece 19 is smallest at the upstream ends 22A of the side restraint plates 22. As shown in FIG. 3, the height of the lower ends of the side restraint plates 22 is the same as the lower surface of the workpiece 19.

[0032] In the second embodiment, a side restraint plate 22 different from the side restraint plate 22 of the first embodiment is used. The side restraint plate 23 of the second embodiment is a flat plate having a length of 60 mm in the passing direction T of the abrasive 14. As shown in FIG. 5 , the upstream end 23A of the side restraint plate 23 of the second embodiment is located upstream of the upstream end 22A of the side restraint plate 22 of the first embodiment. Specifically, the upstream end 23A of the pair of side restraint plates 23 is located at the same position as the rotation center 19R of the workpiece 19 in the passing direction T of the abrasive 14, and is located 25 mm downstream of the upstream end 19A of the workpiece 19. In a plan view, the distance between the side restraint plate 23 and the tip circle of the workpiece 19 is smallest at the upstream end 23A of the side restraint plate 23. The configuration other than the side restraint plate 23 is the same as that of the first embodiment.

[0033] Comparative embodiment 1 uses the same upper restraint plate 21 as the upper restraint plate 21 used in embodiments 1 and 2, but does not include side restraint plates, as shown in Fig. 6. Comparative embodiment 2 does not include either an upper restraint plate or a side restraint plate, as shown in Fig. 7.

[0034] The side restraint plates 24 used in Comparative Example 3 are flat plates with a length of 80 mm in the passing direction T of the abrasive 14. As shown in FIG. 8 , the upstream ends 24A of the side restraint plates 24 in Comparative Example 3 are located upstream of the upstream ends 23A of the side restraint plates 23 in Embodiment 2. Specifically, the upstream ends 24A of the pair of side restraint plates 24 are located 20 mm upstream of the rotation center 19R of the workpiece 19 in the passing direction T of the abrasive 14 and 5 mm downstream of the upstream ends 19A of the workpiece 19. In a plan view, the distance between the side restraint plates 24 and the workpiece 19 is smallest at a position 24C (the same position as the rotation center 19R of the workpiece 19) 20 mm downstream of the upstream ends 24A of the side restraint plates 24. The configuration other than the side restraint plates 24 is the same as in Embodiments 1 and 2.

[0035] The side restraint plates 25 used in Comparative Example 4 are flat plates with a length of 120 mm in the direction T of passage of the abrasive 14, the same as the upper restraint plate 21. As shown in FIG. 9 , the upstream ends 25A of the side restraint plates 25 in Comparative Example 4 are located upstream of the upstream ends 24A of the side restraint plates 24 in Comparative Example 3. Specifically, the upstream ends 25A of the pair of side restraint plates 25 are located 60 mm upstream of the center of rotation 19R of the workpiece 19 in the direction T of passage of the abrasive 14, and 35 mm upstream of the upstream ends 19A of the workpiece 19. In a plan view, the distance between the side restraint plates 25 and the workpiece 19 is smallest at position 25C, which is 60 mm downstream of the upstream ends 25A of the side restraint plates 25 (the same position as the center of rotation 19R of the workpiece 19). The configuration other than the side restraint plates 25 is the same as in Embodiments 1 and 2.

[0036] The change in surface roughness over time is shown in Table 1. The polishing efficiency was evaluated as follows: when the change in surface roughness was 0.1 μm or more, it was marked as "◎ (good)". When the change in surface roughness was less than 0.1 μm and 0.07 μm or more, it was marked as "◯ (fairly good)". When the change in surface roughness was less than 0.07 μm and 0.03 μm or more, it was marked as "△ (fairly poor)". When the change in surface roughness was less than 0.03 μm, it was marked as "× (poor)".

[0037] [Table 1]

[0038] The polishing efficiency of the constrained embodiment of the first embodiment was evaluated as "Excellent" after 5, 10, 15, and 20 minutes of polishing. In the first embodiment, the upstream end 22A of the side constraining plate 22 is located downstream of the upstream end 19A of the workpiece 19 in the direction of movement of the abrasive 14. Specifically, the upstream end 22A is located downstream of the center of rotation 19R and center of gravity 19G of the workpiece 19. Therefore, the side constraining plate 22 is not located upstream of the center of rotation 19R and center of gravity 19G of the workpiece 19. Therefore, of the abrasive 14 moving toward the gap between the side constraining plate 22 and the workpiece 19, a portion of the abrasive 14 moving in the region upstream of the upstream end 19A of the workpiece 19 and the region upstream of the center of rotation 19R and center of gravity 19G of the workpiece 19 can escape in the direction away from the workpiece 19 (radial direction R).

[0039] Furthermore, because the shape of the workpiece 19 (the path traced by the tooth tip circle of the workpiece 19) in a plan view is circular, the distance between the side restraint plate 22 and the tooth tip circle of the workpiece 19 is smallest at the upstream end 22A of the side restraint plate 22 in the passing direction T (movement direction) of the abrasive 14. Therefore, the side restraint plate 22 does not exist upstream of the position where the distance between the side restraint plate 22 and the workpiece 19 is smallest. Of the abrasive 14 heading toward the gap between the side restraint plate 22 and the workpiece 19, some of the abrasive 14 moving in the region upstream of the position where the distance between the side restraint plate 22 and the workpiece 19 is smallest can escape in a direction away from the workpiece 19 (radial direction).

[0040] According to the restraint configuration of the first embodiment, the abrasive 14 heading toward the gap between the side restraint plates 22 and the workpiece 19 is less likely to become congested before the gap, and can therefore enter the gap without reducing its moving speed. In the process of passing through the gap, a pressing force is applied from the abrasive 14 to the workpiece 19. This allows the abrasive 14 to come into contact with the workpiece 19 while maintaining an appropriate relative moving speed and pressing force, thereby improving the polishing force and polishing efficiency.

[0041] The polishing efficiency of the constrained configuration of embodiment 2 was evaluated as "good" (fairly good) at each of the polishing times of 5, 10, 15, and 20 minutes. In embodiment 2, the upstream end 23A of the side constraining plate 23 is located at the same position as the center of rotation 19R and center of gravity 19G of the workpiece 19 in the moving direction of the abrasive 14 (a position downstream of the upstream end 19A of the workpiece 19). Therefore, the side constraining plate 23 is not located upstream of the center of rotation 19R and center of gravity 19G of the workpiece 19. Therefore, of the abrasive 14 heading toward the gap between the side constraining plate 23 and the workpiece 19, a portion of the abrasive 14 moving in the region upstream of the center of rotation 19R of the workpiece 19, i.e., the region upstream of the upstream end 23A of the side constraining plate 23, can escape in the direction away from the workpiece 19 (radial direction R).

[0042] Furthermore, because the workpiece 19 has a circular shape in a plan view, the distance between the side restraint plates 23 and the workpiece 19 is smallest at the upstream ends 23A of the side restraint plates 23 in the passing direction T (movement direction) of the abrasive 14. Because the upstream ends 23A of the side restraint plates 23 are at the same position as the rotation center 19R of the workpiece 19, no side restraint plates 23 are present upstream of the rotation center 19R of the workpiece 19. Of the abrasive 14 heading toward the gap between the side restraint plates 23 and the workpiece 19, some of the abrasive 14 moving in the region upstream of the rotation center 19R of the workpiece 19, i.e., the region upstream of the position where the distance between the side restraint plates 23 and the workpiece 19 is smallest, can escape in a direction away from the workpiece 19.

[0043] Therefore, according to the restraint form of embodiment 2, as in embodiment 1, the abrasive 14 heading toward the gap between the lateral restraint plate 23 and the workpiece 19 is less likely to become congested in front of the gap and can enter the gap without reducing its moving speed, thereby improving the polishing efficiency.

[0044] The polishing efficiency of the comparative embodiment 1, in which the constraint mode is comparative, was evaluated as "Δ (slightly poor)" at each of the polishing times of 5, 10, 15, and 20 minutes. In comparative embodiment 1, the relative movement speed of the abrasive 14 with respect to the workpiece 19 is roughly the same as in embodiments 1 and 2. However, since there are no side constraint plates, the pressing force from the abrasive 14 to the workpiece 19 when the abrasive 14 passes by the side of the workpiece 19 is insufficient compared to embodiments 1 and 2. It is presumed that this is why the polishing efficiency was lower than in embodiments 1 and 2.

[0045] The evaluation of the polishing efficiency of the comparative constraining form 2 was "× (poor)" at all times after 5, 10, 15, and 20 minutes of polishing time. Compared to the comparative form 1, the comparative form 2 does not have the upper constraining plate 21. Therefore, it is presumed that the pressing force from the abrasive 14 to the upper surface of the workpiece 19 and the outer surface on the upstream side of the workpiece 19 is low, and the polishing efficiency is reduced accordingly.

[0046] The polishing efficiency of the comparative constraining configuration 3 was evaluated as "× (poor)" at each of the polishing times of 5, 10, 15, and 20 minutes. In the comparative configuration 3, in the passing direction T of the abrasive 14, the position of the upstream end 24A of the side constraining plate 24 is downstream of the upstream end 19A of the workpiece 19, but upstream of the rotation center 19R and center of gravity 19G of the workpiece 19. The distance between the side constraining plate 24 and the workpiece 19 is smallest at a position 24C (rotation center 19R of the workpiece 19) downstream of the upstream end 24A of the side constraining plate 24, and therefore the upstream end of the side constraining plate 24 is located upstream of the position where the distance between the side constraining plate 24 and the workpiece 19 is smallest.

[0047] The abrasive 14 that has entered between the upstream ends of the pair of side restraint plates 24 cannot escape in a direction away from the workpiece 19 (radial direction R) as it moves toward the minimum gap between the side restraint plates 24 and the workpiece 19. Moreover, the radial width of the movement path of the abrasive 14 from the upstream ends 24A of the pair of side restraint plates 24 to the minimum gap between the side restraint plates 24 and the workpiece 19 gradually narrows toward the downstream side. Therefore, the abrasive 14 moving toward the minimum gap between the side restraint plates 24 and the workpiece 19 becomes congested between the upstream ends of the pair of side restraint plates 24, reducing its movement speed. Therefore, it is presumed that the polishing force and polishing efficiency were reduced in Comparative Example 3.

[0048] The polishing efficiency of the comparative constraining configuration 4 was evaluated as "× (poor)" at each of the polishing times of 5, 10, 15, and 20 minutes. In the comparative configuration 4, the position of the upstream end 25A of the side constraining plate 25 is upstream of the upstream end 19A of the workpiece 19 in the passing direction T of the abrasive 14. The distance between the side constraining plate 25 and the workpiece 19 is smallest at a position 25C (rotation center 19R of the workpiece 19) downstream of the upstream end 25A of the side constraining plate 25, and therefore the side constraining plate 25 is located upstream of the position where the distance between the side constraining plate 25 and the workpiece 19 is smallest.

[0049] The abrasive 14 that has entered between the pair of side restraint plates 25 cannot escape in a direction away from the workpiece 19 (radial direction R) as it moves toward the minimum gap between the side restraint plates 25 and the workpiece 19. Moreover, the width of the movement path leading to the minimum gap between the side restraint plates 25 and the workpiece 19 gradually narrows toward the downstream side. Therefore, the abrasive 14 moving toward the minimum gap between the side restraint plates 25 and the workpiece 19 becomes congested between the pair of side restraint plates 25, causing a decrease in movement speed. For this reason, it is presumed that the polishing force and polishing efficiency decreased in Comparative Example 4.

[0050] The barrel polishing machine of Example 1 includes a rotatable barrel tank 10, abrasives 14, a support member 16, and side restraint plates 22 and 23. The abrasives 14 are contained in the barrel tank 10 to form a polishing layer 15, and move in the circumferential direction as the barrel tank 10 rotates. The support member 16 supports the workpiece 19 while immersed in the abrasives 14 (in the polishing layer 15). The support member 16 supports the workpiece 19 rotatably. The side restraint plates 22 and 23 are arranged to be spaced apart from the workpiece 19 in the radial direction R of the barrel tank 10.

[0051] The restraint configurations of Embodiments 1 and 2 of Example 1 have the following two technical features. The first feature is that, in the passing direction T of the abrasive 14, the upstream ends 22A, 23A of the side restraint plates 22, 23 are disposed at the same position as the center of rotation 19R or the center of gravity 19G of the workpiece 19, or at a position downstream of the center of rotation 19R or the center of gravity 19G. In other words, the side restraint plates 22, 23 are not located upstream of the center of rotation 19R or the center of gravity 19G of the workpiece 19. With this arrangement, of the abrasive 14 heading toward the gap between the side restraint plates 22, 23 and the workpiece 19, a portion of the abrasive 14 moving in the region upstream of the center of rotation 19R or the center of gravity 19G of the workpiece 19 can escape in a direction away from the workpiece 19.

[0052] Since the shape of the workpiece 19 (the path traced by the tip circle of the workpiece 19) in a plan view is circular, the positions of the center of rotation 19R and center of gravity 19G of the workpiece 19 in the passing direction T of the abrasive 14 are the same as the part of the workpiece 19 where the width dimension in the radial direction perpendicular to the passing direction T of the abrasive 14 is maximum. Therefore, the first feature is that, since the side restraint plates 22, 23 are not present upstream of the part of the workpiece 19 where the width dimension is maximum, of the abrasive 14 heading toward the gap between the side restraint plates 22, 23 and the workpiece 19, a part of the abrasive 14 moving in the region upstream of the part of the workpiece 19 where the width dimension is maximum can be said to escape in a direction away from the workpiece 19.

[0053] The second feature is that the distance between the side restraint plates 22, 23 and the tip circle of the workpiece 19 is smallest at the upstream ends 22A, 23A of the side restraint plates 22, 23 in the direction of movement of the abrasive 14, so the side restraint plates 22, 23 do not exist upstream of the position where the distance between the side restraint plates 22, 23 and the workpiece 19 is smallest. Of the abrasive 14 heading toward the gap between the side restraint plates 22, 23 and the workpiece 19, some of the abrasive 14 moving in the area upstream of the position where the distance between the side restraint plates 22, 23 and the workpiece 19 is smallest can escape in a direction away from the workpiece 19.

[0054] According to the above two technical features, the abrasive 14 heading toward the gap between the side restraint plates 22, 23 and the workpiece 19 is less likely to become congested, thereby suppressing a decrease in the moving speed of the abrasive 14 coming into contact with the workpiece 19. Therefore, according to the barrel polishing machine to which the first and second embodiments of this Example 1 are applied, the polishing force and the polishing efficiency can be improved.

[0055] Moreover, the workpiece 19 is arranged only in an area away from the rotation shaft 13 of the barrel tank 10 in a plan view. The pair of side restraint plates 22, 23 are arranged at an inner peripheral position closer to the rotation shaft 13 with respect to the workpiece 19, and at a position farther from the rotation shaft 13 with respect to the workpiece 19 (a position closer to the peripheral wall portion 12). According to this configuration, the pair of side restraint plates 22, 23 can efficiently polish the workpiece 19.

[0056] The barrel polishing machine also includes an upper restraint plate 21 that covers the workpiece 19 from above while it is immersed in the abrasive 14 (in the polishing layer 15). Even when the workpiece 19 is located in an upper layer region of the polishing layer 15, the upper restraint plate 21 can press the abrasive 14 against the upper surface of the workpiece 19, thereby increasing the polishing force. Furthermore, in the direction of movement of the abrasive 14, the upstream end of the upper restraint plate 21 is located upstream of the upstream ends 22A, 23A of the side restraint plates 22, 23, so that the upper surface of the workpiece 19 can be polished effectively. Furthermore, the upper restraint plate 21 prevents the abrasive 14 from escaping upward between the workpiece 19 and the side restraint plates 22, 23, so that the outer peripheral surface (side surface) of the workpiece 19 can also be polished effectively.

[0057] <Other Examples> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments are also included within the technical scope of the present invention. The side restraint plates may be arranged only on the outer periphery far from the rotation axis relative to the workpiece, or only on the inner periphery close to the rotation axis relative to the workpiece. In this case, an auxiliary plate may be arranged on the side where no side restraint plate is arranged. The upstream end of the auxiliary plate may be arranged at a position upstream of the upstream end of the workpiece, or at a position upstream of the center of rotation or center of gravity of the workpiece. The distance between the auxiliary plate and the workpiece may be smallest at a position different from the upstream end of the auxiliary plate. The upstream ends of the pair of side restraint plates may be disposed at different positions from each other in the direction in which the abrasive passes. The downstream ends of the pair of side restraint plates may be disposed at different positions in the direction in which the abrasive passes. In a plan view, the arrangement of a pair of flat lateral restraint plates is not limited to a parallel relationship, but may be such that the distance between their upstream ends is wider than the distance between their downstream ends, or such that the distance between their upstream ends is narrower than the distance between their downstream ends. The flat side restraint plates may be arranged obliquely with respect to the direction of passage of the abrasive material in a plan view. The upper ends of a pair of lateral restraint plates may be positioned at different heights. The lower ends of a pair of side restraint plates may be positioned at different heights. The planar shape of the side restraint plates is not limited to a straight line, but may be curved at an obtuse angle or may be an arc concentric with the barrel. When viewed parallel to the abrasive passage direction, the side restraint plates may be inclined relative to the rotation axis of the barrel tank. The height of the lower end of the side restraint plate may be higher than the bottom surface of the workpiece or lower than the bottom surface of the workpiece.

[0058] The upstream end of the upper restraint plate may be positioned downstream of the upstream end of the workpiece or downstream of the center of rotation or center of gravity of the workpiece. The upstream end of the upper restraint plate may be positioned at the same position as the upstream end of the side restraint plate in the direction of abrasive passage, or may be positioned downstream of the upstream end of the side restraint plate. The downstream end of the upper restraint plate and the downstream end of the side restraint plate may be positioned at different positions in the direction in which the abrasive passes. The upper restraint plate does not have to be oriented perpendicular to the rotation axis of the barrel tank, but may be arranged at an angle to the rotation axis. The upper restraint plate may not be provided.

[0059] In plan view, the position of the center of rotation of the workpiece and the position of the center of gravity of the workpiece may be different. The rotation axis of the barrel tank may be tilted relative to the vertical direction. The workpiece may rotate around an axis diagonal to the rotation axis of the barrel tank. In plan view, the rotation center of the work (support member) may be arranged concentrically with the rotation axis of the barrel tank. The rotation of the workpiece during grinding may be in the form of continuous rotation in only one direction, either forward or reverse, intermittent rotation in only one direction, alternating continuous rotation in the forward direction and continuous rotation in the reverse direction, or alternating intermittent rotation in the forward direction and intermittent rotation in the reverse direction. The workpiece may be ground in a stationary position without rotation. The planar shape of the workpiece may be other than circular (oval, elliptical, rectangular, etc.). In the above Example 1, water and compound are poured into the barrel tank, but water and compound do not have to be poured. [Explanation of symbols]

[0060] 10...Barrel tank 13...Rotation axis 14...Abrasive material 16...Support member 19...Work 19A...Upstream end of workpiece 19G...Center of gravity of workpiece 19R...Center of rotation of workpiece 21...Upper restraint plate 22...Side restraint plate 22A...Upstream end of side restraint plate 23...Side restraint plate 23A...Upstream end of side restraint plate

Claims

1. A barrel tank that can rotate around a vertical rotation axis; an abrasive material accommodated in the barrel tank and moving in a circumferential direction as the barrel tank rotates; a support member having a support shaft parallel to the rotation shaft; and side restraint plates arranged at intervals in the radial direction of the barrel tank relative to the axis of the support shaft, the support member rotatably supports the workpiece fixed to the lower end of the support shaft while immersing the workpiece in the abrasive material; In a barrel polishing machine, the upstream ends of the side restraint plates are arranged at the same position as the axis of the support shaft or at a position downstream of the axis of the support shaft in the moving direction of the abrasive.

2. A barrel tank that can rotate around a vertical rotation axis; an abrasive material accommodated in the barrel tank and moving in a circumferential direction as the barrel tank rotates; a support member having a support shaft parallel to the rotation shaft; and side restraint plates arranged at intervals in the radial direction of the barrel tank relative to the axis of the support shaft, the support member rotatably supports the workpiece fixed to the lower end of the support shaft while immersing the workpiece in the abrasive material; In a barrel polishing apparatus, in a plan view, the distance between the side restraint plates and the axis of the support shaft is smallest at the upstream end of the side restraint plates in the moving direction of the abrasive.

3. The support shaft, in a plan view, positions the workpiece only in an area away from the rotation axis of the barrel tank, 3. The barrel polishing machine according to claim 1, wherein the pair of side restraint plates are disposed at a position closer to the rotary shaft with respect to the support shaft and at a position farther from the rotary shaft with respect to the support shaft.

4. 3. The barrel polishing machine according to claim 1, further comprising an upper restraining plate that is immersed in the abrasive and covers the workpiece from above.

5. 5. The barrel polishing machine according to claim 4, wherein the upstream end of the upper restraint plate is located upstream of the upstream ends of the side restraint plates in the moving direction of the abrasive material.

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