Rotary polishing tool

Abstract

To provide a rotary polishing tool in which falling of a snap ring can be prevented while forming polishing sheets in a meandered shape.SOLUTION: A polishing member 3 that polishes an object to be polished with a peripheral surface is provided. The polishing member 3 is formed by a plurality of stacked polishing sheets 6 each having a center hole 5. A holding shaft 2 is inserted to the center hole 5. An inner peripheral part of the polishing member 3 is pressed by a pair of press rings 7a, 7b externally fit to the holding shaft 2. The polishing member 3 is held in an outer peripheral side of the holding shaft 2. The polishing sheets 6 are formed in a meandered shape. A press surface 8 of the press rings 7a, 7b is formed in a meandered shape corresponding to the meandered shape of the inner peripheral part of the polishing sheets 6. A peripheral groove 9 is formed in an outer peripheral surface of the holding shaft 2. A C-shaped snap ring 10 that regulates slipping out of the press rings 7a, 7b is mounted to the peripheral groove 9. A detachment prevention part 11 is provided in the press rings 7a, 7b. By regulating an increase in the diameter of the snap ring 10 by the detachment prevention part 11, falling of the snap ring 10 from the peripheral groove 9 is blocked.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotary abrasive tool suitable for removing scale and scratches from the surface of, for example, a steel plate. [Background technology]

[0002] Generally, scale on the surface of steel plates is removed by surface polishing. This surface polishing is an important step for post-processing of steel plates. For example, when polished steel plates are bent to form the walls of oil tanks, if scratches on the surface of the supplied steel plate remain on the polished surface, the bending stress can cause the steel plate to break. Therefore, surface polishing must be performed to ensure that the polished surface is free of scratches. In addition, a coating film is usually applied to the polished surface for surface protection, and the polished surface must have a surface roughness suitable for coating formation.

[0003] One method for forming this type of polished surface is to use a rotary polishing tool in which a number of disc-shaped coated abrasive sheets are stacked together to form a cylindrical polishing member, which is rotated around its central axis to polish the surface to be polished with the circumferential surface, i.e., the periphery of each coated abrasive sheet.

[0004] However, when a polishing member consisting of simply a number of flat abrasive cloths stacked on top of each other is used, when viewed microscopically, the surface to be polished is only polished at the periphery of each abrasive cloth, and not polished between the abrasive cloths, and the finished surface to be polished will have many streaky irregularities caused by the peripheries of the individual abrasive cloths coming into contact with each other.

[0005] In contrast to this, Patent Document 1 discloses a rotary polishing tool in which the peripheral edges of each coated abrasive are moved back and forth in the direction of the central axis while the polishing member is rotated, so that the peripheral edges of the coated abrasive are brought into contact with the entire surface to be polished, thereby preventing the generation of streaky irregularities and finishing the surface to be polished to a desired surface roughness.

[0006] As shown in Fig. 6, the rotary abrasive tool of Patent Document 1 has a polishing member 102 made up of multiple layers of coated abrasive 101 stacked on top of each other, with the periphery of each coated abrasive 101 deformed into a serpentine shape. In this rotary abrasive tool, the center of the polishing member 102 is held by a holding shaft 103, and both sides are pressed by pressure rings 104. A C-shaped snap ring 105 is fitted into a circumferential groove formed on the outer periphery of the holding shaft 103 to prevent the pressure ring 104 from slipping out. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] WO2006 / 003712 (paragraphs 0010-0012, 0014, 0024, Figure 1) Summary of the Invention [Problem to be solved by the invention]

[0008] When a polishing member is rotated at high speed to polish a surface to be polished, if there is, for example, a foreign object or a protrusion on the surface to be polished, the polishing member may come into contact with this foreign object or protrusion, causing an impact force in the circumferential direction to act on the polishing member.

[0009] If the abrasive member is simply a stack of flat abrasive cloths, the impact force in the circumferential direction can be absorbed by a portion of the abrasive cloths or the entire abrasive member shifting circumferentially relative to the retaining shaft and pressure ring.

[0010] However, when the periphery of each coated abrasive is deformed into a serpentine shape as in Patent Document 1, the serpentine shapes of the coated abrasives must interlock with each other, and the pressing surface of the pressure ring must also be formed into a serpentine shape that interlocks with the serpentine shapes of the coated abrasives. Due to this interlocking, when an impact force is applied in the circumferential direction, the pressure ring becomes one with the abrasive member and shifts circumferentially relative to the holder shaft, and this shift of the pressure ring relative to the holder shaft may cause the snap ring to fall off.

[0011] More specifically, the rotary grinding tool shown in a front view in Figure 7(a) has a C-shaped snap ring 105 attached to a circumferential groove formed on the outer periphery of the holding shaft 103 to prevent the pressure ring 104 from slipping out, and the snap ring 105 is clamped between the pressure ring 104, which receives a reaction force from the grinding member 102, and the groove wall of the circumferential groove of the holding shaft 103.

[0012] When the groove wall of the retaining shaft 103 that clamps the snap ring 105 and the pressure ring 104 shift circumferentially and move relative to each other, the frictional force between them causes the snap ring 105 to move integrally with either the pressure ring 104 or the retaining shaft 103. In this case, there is no problem if the entire snap ring 105 moves in the same direction, but as shown in Figure 7(b), if both ends of the snap ring 105 move in opposite directions, the C-shaped snap ring 105 will expand in diameter and rise up from the circumferential groove, and there is a risk that it will fall off the retaining shaft 103.

[0013] SUMMARY OF THE INVENTION An object of the present invention is to provide a rotary abrasive tool that can prevent the snap ring from falling off while forming a serpentine abrasive cloth. [Means for solving the problem]

[0014] In order to achieve the above object, the rotary grinding tool of the present invention has a holder shaft attached to a rotating shaft, and holds a substantially cylindrical grinding member on the outer periphery of the holder shaft, which rotates integrally with the holder shaft around its central axis, and grinds an object with the peripheral surface of the grinding member. The grinding member is made of a number of substantially circular coated abrasive sheets, each having a central hole, stacked in the axial direction of the central axis. The holder shaft is inserted into the central hole, and a pair of pressure rings fitted around the holder shaft press and hold the inner periphery in the axial direction of the central axis. The coated abrasive is formed in a serpentine shape that moves back and forth in the axial direction of the central axis relative to the circumferential direction of the grinding member, and the pressing surface of the pressure ring is formed in a serpentine shape that corresponds to the serpentine shape of the inner periphery of the coated abrasive. The holder shaft has a circumferential groove on its outer surface, into which a C-shaped snap ring is attached to prevent the pressure ring from slipping out. The pressure ring has a stopper that regulates the radial expansion of the snap ring to prevent it from falling out of the circumferential groove.

[0015] According to the above configuration, the coated abrasive constituting the polishing member is formed in a serpentine shape, so that when the polishing member is rotated for polishing, the periphery of the coated abrasive moves back and forth in the axial direction of the central axis, thereby uniformly polishing the surface to be polished. Because the pressure ring engages with the serpentine shape of the coated abrasive, when the polishing member receives a circumferential impact force, the pressure ring moves circumferentially relative to the retaining shaft, which may cause friction between the snap ring, the pressure ring, and the retaining shaft to expand the diameter of the C-shaped snap ring. In response, the pressure ring is provided with a stopper, which restricts the expansion of the snap ring and prevents it from falling out of the circumferential groove formed on the outer surface of the retaining shaft.

[0016] The stopper can also be engaged with a bulge formed on the end of the C-shaped snap ring for opening and closing operations.

[0017] A bulge is formed at the end of the snap ring to ensure space for the hole, and C-shaped snap rings are often opened and closed by hooking a tool into this hole. By using this bulge to engage a stopper, the circumferential movement of the snap ring end can be stopped and the expansion of the snap ring can be efficiently restricted. Note that instead of engaging the stopper with the bulge used for opening and closing operations, it is also possible to restrict the expansion of the snap ring by engaging stoppers radially outward at multiple points in the center of the C-shaped snap ring.

[0018] Furthermore, the stopper can be engaged with the rear bulge at the rotation direction of the grinding member out of the bulges at both ends of the snap ring.

[0019] With this configuration, the stopper engages with the rear bulge in the rotational direction, making it easier to attach the snap ring to the circumferential groove than with a structure in which the stopper engages with each of the bulges on both sides, or a structure in which the stopper engages with multiple points in the center of the C-shaped snap ring.

[0020] Furthermore, by engaging the stopper with the rear bulge, even if the polishing member and pressure ring receive an impact force from the surface to be polished and move rearward in the rotational direction relative to the retaining shaft, the rear end of the snap ring can be forced to move integrally with the pressure ring, preventing the snap ring from expanding in diameter. In other words, if the front end tries to move integrally with the pressure ring, the snap ring will not expand in diameter, and if the front end tries to move integrally with the retaining shaft, only a force will act to reduce the diameter of the snap ring, and the snap ring fitted in the circumferential groove will neither reduce nor expand in diameter.

[0021] Furthermore, for example, if the stopper is engaged with the front bulge in the rotational direction, it is possible that the engagement between the stopper and the front bulge will be disengaged as the polishing member and pressure ring move due to impact force, but the snap ring will be prevented from falling off unless a particularly strong impact force is received by the stopper until it moves rearward and engages with the rear bulge.

[0022] The stopper may also be provided on one of the pair of pressure rings.

[0023] With this configuration, for example, it is possible to omit a stopper for the pressure ring on the base end side of the rotating shaft, which is relatively unlikely to vibrate and the snap ring is unlikely to fall off. [Effects of the Invention]

[0024] As described above, according to the present invention, the coated abrasive constituting the polishing member is formed in a serpentine shape, so that when the polishing member is rotated for polishing, the periphery of the coated abrasive is moved back and forth in the axial direction of the central axis, thereby uniformly polishing the surface to be polished. Furthermore, because the pressure ring is provided with a stopper, even if the pressure ring, which engages with the serpentine shape of the coated abrasive, moves circumferentially relative to the holder shaft when the polishing member is subjected to an impact force, the C-shape of the snap ring can be prevented from expanding in diameter, and it is possible to prevent the snap ring from falling off the holder shaft while forming the coated abrasive in a serpentine shape. [Brief explanation of the drawings]

[0025] [Figure 1] 1A is a front view of a rotary grinding tool according to the present invention, and FIG. 1B is a right side view of the upper half of FIG. 1B, and a vertical cross-sectional view of the lower half of FIG. [Figure 2] An exploded perspective view of a rotary grinding tool [Figure 3] (a) is a front view of the front pressure ring, and (b) is a right side view of the front pressure ring. [Figure 4] (a) is a front view of the polishing unit, (b) is its AA cross section, and (c) is its BB cross section. [Figure 5] A diagram explaining how the stopper prevents the snap ring from falling off [Figure 6] Right side view of a conventional rotary grinding tool [Figure 7] This is a front view of a conventional rotary grinding tool, in which (a) shows the snap ring in its normal state and (b) shows the snap ring in its expanded state. DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a rotary grinding tool according to the present invention will be described with reference to the drawings.

[0027] As shown in Figures 1 and 2, the rotary grinding tool 1 has a retaining shaft 2 attached to a rotating shaft driven by a drive source, which retains a substantially cylindrical grinding member 3 on its outer periphery, and the grinding member 3 rotates integrally with the retaining shaft 2 around its central axis 4, grinding the workpiece with its peripheral surface. The grinding member 3 is made of a number of substantially circular abrasive cloth papers 6 each having a central hole 5 stacked in the axial direction of the central axis 4, and the retaining shaft 2 is inserted into the central hole 5, and the inner periphery is pressed in the axial direction of the central axis 4 by a pair of pressure rings 7a, 7b fitted around the retaining shaft 2 to hold it.

[0028] Furthermore, in the rotary grinding tool 1, the coated abrasive 6 is formed in a serpentine shape that moves back and forth in the axial direction of the central axis 4 relative to the circumferential direction of the grinding member 3, and the pressing surfaces 8 of the pressure rings 7a, 7b are formed in a serpentine shape that corresponds to the serpentine shape of the inner periphery of the coated abrasive 6. Circumferential grooves 9 are formed at both ends of the retaining shaft 2, and C-shaped snap rings 10 are attached to each circumferential groove 9 to prevent the pressure rings 7a, 7b from slipping out. One of the pressure rings, 7a, is provided with a stopper 11 that restricts the radial expansion of the snap ring 10 to prevent it from falling out of the circumferential groove 9.

[0029] The retaining shaft 2 is cylindrical, for example made of steel, into which a rotating shaft (not shown) can be inserted, and support plates 12 that cover both ends are formed with bearings 13 through which the rotating shaft passes.Furthermore, circumferential grooves 9 are formed on the outer surfaces of both ends, sandwiching the central portion that holds the polishing member 3, so that they continue in the circumferential direction.

[0030] The polishing member 3 consists of a pair of polishing units 14 provided at both ends in the direction of the central axis, and an intermediate portion 15 provided between these polishing units 14, and is structured so that the intermediate portion 15 is clamped in the axial direction of the central axis 4 by the polishing units 9 on both sides.

[0031] 3, the polishing unit 14 is formed by stacking multiple sheets of coated abrasive 6 and clamping them with a ring-shaped inner metal fitting 16 inserted into the central hole 5. The inner metal fitting 16 is composed of a cylindrical portion 16a that fits onto the holder shaft 2 and flange portions 16b that are bent on both sides in the axial direction and clamp the peripheral portion of the central hole 5 of the coated abrasive 6. Parts of the inner metal fitting 16 are pressed by upper and lower press dies to bend it into a serpentine shape that moves back and forth in the axial direction, thereby forming the peripheral edge of the coated abrasive 6 of the polishing unit 14 into a serpentine shape.

[0032] The intermediate portion 15 is made up of a number of sheets of abrasive cloth 6 stacked in the axial direction, and is clamped and pressed in the axial direction between a pair of polishing units 14, conforming to the shape of the polishing units 14, so that the peripheral edges of each sheet of abrasive cloth 6 that makes up this intermediate portion 15 are shaped in a serpentine shape.

[0033] The abrasive cloth 6 is a base paper such as paper, cloth, or net coated with abrasive grains such as alumina or silicon carbide, and examples thereof include those manufactured by Riken Corundum Co., Ltd. and Sankyo Rikagaku Co., Ltd.

[0034] The pressure rings 7a, 7b are ring-shaped with inner and outer diameters set to be approximately the same as those of the inner metal fitting 16 of the polishing unit 14, and the pressure surfaces 8 set on the inner surfaces in the axial direction are formed in a serpentine shape corresponding to the serpentine shape of the inner metal fitting 16. The pressure rings 7a, 7b are arranged on both outsides of the polishing unit 14 so as to sandwich the polishing member 3 in the axial direction, and are fixed to both ends of the holder shaft 2 by circumferential grooves 9 and snap rings 10 in a state in which they press against the inner periphery of the coated abrasive 6 that constitutes the polishing member 3 via the inner metal fitting 16.

[0035] Snap ring 10 is an elastic C-shaped metal fitting with an inner diameter slightly smaller than the bottom of circumferential groove 9, a thickness that allows it to fit into circumferential groove 9, and an outer diameter that is sufficiently smaller than the outer diameters of pressure rings 7a, 7b, and bulges 17a, 17b are formed on both ends thereof for use in opening and closing operations. When a tool is hooked onto engagement holes 18 formed in bulges 17a, 17b to expand snap ring 10, and the tool is then aligned with circumferential groove 9 and released, snap ring 10 fits into circumferential groove 9 while protruding from the outer circumferential surface of retaining shaft 2, preventing pressure rings 7a, 7b from slipping out.

[0036] Of the snap rings 10 on both sides, for example, the snap ring 10 located on the tip side of the rotating shaft is prevented from falling off from the circumferential groove 9 due to expansion of its diameter by engaging the stopper 11 with the rear bulge 17b of the bulges 17a, 17b at both ends in the rotational direction of the grinding member 3.

[0037] As shown in FIG. 4, the stopper 11 protrudes from the surface opposite to the pressing surface 8 of one of the pressing rings 7a, and is positioned on the outer periphery of the snap ring 10, so as to engage with the bulging portion 17b from the front in the circumferential direction in the rotational direction of the grinding member 3.

[0038] Next, how the stopper 11 prevents the snap ring 10 from falling off will be described.

[0039] As shown in Figure 5, when the holder shaft 2 is rotated at high speed in the axial rotation direction 19 to polish the surface to be polished with the circumferential surface of the polishing member 3, if there is, for example, a foreign object or a protrusion on the surface to be polished, the polishing member 3 will come into contact with the foreign object or protrusion, and an impact force 20 will act on the polishing member 3 backward in the axial rotation direction 19. This impact force 20 will cause the pressure ring 7a to move together with the polishing member 3 relative to the holder shaft 2 in a displacement direction 21 (the opposite direction to the axial rotation direction 19).

[0040] When the pressure ring 7a is displaced in the displacement direction 21, the C-shaped snap ring 10 expands in diameter due to the frictional force between the retaining shaft 2 and the pressure ring 7a, which may cause it to float up from the circumferential groove 9 and fall off the retaining shaft 2, but the stopper 11 restricts the expansion, preventing the snap ring 10 from falling off.

[0041] To explain in more detail, first, the pressure ring 7a receives a reaction force from the grinding member 3 in the axial direction of the central axis 4, thereby clamping the snap ring 10 between itself and the groove wall of the circumferential groove 9 of the retaining shaft 2, and a strong frictional force acts between the retaining shaft 2, the pressure ring 7a, and the snap ring 10.

[0042] When the pressure ring 7a is displaced in the displacement direction 21 relative to the holder shaft 2, the frictional force between the holder shaft 2 and the pressure ring 7a moves each part of the snap ring 10 integrally with either the holder shaft 2 or the pressure ring 7a.

[0043] When the front bulge 17a of the snap ring 10 moves integrally with the retaining shaft 2 in the axial rotation direction 19, regardless of the direction of movement of the rear bulge 17b, a force acts only in the direction that reduces the diameter of the snap ring 10, so that the snap ring 10 does not fall off.

[0044] On the other hand, when the front bulge 17a of the snap ring 10 moves in the shifting direction 21 due to the frictional force with the pressure ring 7a, and the rear bulge 17b moves in the axial rotation direction 19 due to the frictional force with the retaining shaft 2, the snap ring 10 expands in diameter.

[0045] In contrast, in the structure of this embodiment, the rear bulge 17b engages with the stopper 11 and is forced to move integrally with the pressure ring 7a, thereby restricting the expansion of the snap ring 10 and preventing the snap ring 10 from falling off.

[0046] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. For example, the stopper 11 may be provided not only on one of the pressure rings 7a but also on both pressure rings 7a and 7b. Furthermore, the stopper 11 may be engaged not only with the rear bulge 17b in the rotational direction of the grinding member but also with the front bulge 17a. Furthermore, the stopper 11 may be engaged not only with the bulges 17a and 17b but also with the center of the snap ring 10 in the radial direction. [Explanation of symbols]

[0047] 1 Rotary grinding tool 2 Holding axis 3. Abrasive material 4 Center axis 5 center hole 6 Abrasive cloth paper 7a, 7b Pressure ring 8 Pressing surface 9 Circumferential groove 10 snap ring 11 Stopper 12 Support Plate 13 Bearings 14 Polishing unit 15 Middle section 16 Inner fittings 16a Cylindrical part 16b Flange part 17a, 17b bulge 18 Engagement hole 19 Axis rotation direction 20 Impact Force 21 Direction of deviation

Claims

1. A rotary grinding tool in which a substantially cylindrical grinding member is held on the outer periphery of a holding shaft attached to a rotating shaft, and an object to be ground is ground by the peripheral surface of the grinding member which rotates integrally with the holding shaft around its central axis, The polishing member is made by stacking a number of substantially circular coated abrasive sheets each having a central hole in the axial direction of the central axis, and a holding shaft is inserted into the central hole, and the polishing member is held by a pair of pressure rings fitted around the holding shaft, with the inner periphery pressed in the axial direction of the central axis, the coated abrasive is formed in a serpentine shape reciprocating in the axial direction of the central axis with respect to the circumferential direction of the polishing member, and the pressing surface of the pressing ring is formed in a serpentine shape corresponding to the serpentine shape of the inner circumferential portion of the coated abrasive, A rotary grinding tool characterized in that a circumferential groove is formed on the outer peripheral surface of the retaining shaft, into which a C-shaped snap ring is attached to prevent the pressure ring from slipping out, and the pressure ring is provided with a stopper that regulates the expansion of the snap ring and prevents it from falling out of the circumferential groove.

2. 2. The rotary grinding tool according to claim 1, wherein said stopper engages with a bulge formed on an end of a C-shaped snap ring for opening and closing operations.

3. 3. The rotary grinding tool according to claim 2, wherein the stopper engages with one of the bulges at both ends of the snap ring, the bulge being located rearward in the direction of rotation of the grinding member.

4. 4. The rotary grinding tool according to claim 1, wherein the stopper is provided on one of a pair of pressure rings.

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