Rotary grinding tool

Abstract

To provide a rotary abrasive tool capable of preventing a snap ring from falling off while forming an abrasive cloth into a serpentine shape. [Solution] A polishing member 3 is provided whose peripheral surface polishes an object to be polished. The polishing member 3 is constructed by stacking many sheets of coated abrasive 6 each having a central hole 5. A retaining shaft 2 is inserted into the central hole 5. The inner peripheral portion of the polishing member 3 is pressed by a pair of pressure rings 7a, 7b fitted onto the retaining shaft 2. The polishing member 3 is held on the outer peripheral side of the retaining shaft 2. The coated abrasive 6 is formed in a serpentine shape. The pressing surfaces 8 of the pressure rings 7a, 7b are formed in a serpentine shape corresponding to the serpentine shape of the inner peripheral portion of the coated abrasive 6. A circumferential groove 9 is formed on the outer peripheral surface of the retaining shaft 2. A C-shaped snap ring 10 that prevents the pressure rings 7a, 7b from slipping out is attached to the circumferential groove 9. The pressure rings 7a, 7b are provided with stoppers 11. The stoppers 11 regulate the radial expansion of the snap ring 10 to prevent it from falling out of the circumferential groove 9.

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] In general, the scale on the surface of a steel plate is removed by subjecting the steel plate to surface polishing. This surface polishing is an important step for post-processing of the steel plate. For example, when a polished steel plate is subjected to bending to form the tank wall of an oil tank, if scratches on the surface of the supplied steel plate remain on the polished surface, the steel plate may break due to bending stress. Therefore, the surface polishing must be completed so that no scratches remain on the polished surface. 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 film formation.

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

[0004] However, when using a polishing member that is simply made up of a large number of flat abrasive cloths stacked on top of each other, when viewed microscopically, the surface to be polished is only polished at the edges of each abrasive cloth, and not between the abrasive cloths, and the finished surface to be polished will have numerous streak-like irregularities caused by the edges of each abrasive cloth coming into contact with each other.

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

[0006] As shown in Fig. 6, the rotary abrasive tool of Patent Document 1 has a polishing member 102 made by stacking many sheets of coated abrasive 101, 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, and a C-shaped snap ring 105 is fitted into a circumferential groove formed on the outer circumferential surface 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] Incidentally, when a polishing member is rotated at high speed to polish a surface to be polished, if, for example, a foreign object or a protrusion is present 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 polishing 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 polishing 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, in addition to the serpentine shapes of the coated abrasives meshing with each other, it is necessary to form the pressing surface of the pressure ring into a serpentine shape that meshes with the serpentine shape of the coated abrasives. Due to this meshing, when an impact force is received in the circumferential direction, the pressure ring becomes one with the abrasive member and shifts in the circumferential direction 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] To explain in more detail, 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 circumferential surface 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 presses 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 may fall off the retaining shaft 103.

[0013] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a rotary abrasive tool which is capable of forming a serpentine abrasive cloth while preventing a snap ring from falling off. [Means for solving the problem]

[0014] In order to achieve the above object, the rotary grinding tool of the present invention has a substantially cylindrical grinding member held on the outer periphery of a holder shaft attached to a rotating shaft, and grinds an object to be ground with the peripheral surface of the grinding member which rotates around the central axis of the holder shaft integrally with the holder shaft. The grinding member is a multiplicity of substantially circular coated abrasive sheets each having a central hole stacked in the axial direction of the central axis, and the holder shaft is inserted into the central hole and is held in place by a pair of pressure rings fitted externally to the holder shaft. A number of abrasive cloths with a central hole The inner peripheral portion is pressed and held in the axial direction of the central axis, and the coated abrasive is formed into a meandering shape that reciprocates 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 pressed against the coated abrasive. The inner periphery is reciprocated in the axial direction of the central axis relative to the circumferential direction. The inner circumference of the retaining shaft is formed in a serpentine shape corresponding to the serpentine shape of the inner circumference. On the opposite side to the polishing material A circumferential groove is formed to fit a C-shaped snap ring that prevents the pressure ring from slipping out. Engaged to A stopper is provided to restrict the expansion of the diameter and prevent the bearing from falling off the circumferential groove.

[0015] According to the above-mentioned 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 is moved back and forth in the axial direction of the central axis, so that the surface to be polished can be polished uniformly. Since the pressure ring is engaged with the serpentine shape of the coated abrasive, when the polishing member receives an impact force in the circumferential direction, the pressure ring moves in the circumferential direction relative to the holding shaft, and a frictional force that expands the C-shape of the snap ring may act between the snap ring, the pressure ring, and the holding shaft. In response to this, the pressure ring is provided with a stopper, so that the expansion of the snap ring can be restricted, and the snap ring can be prevented from falling off from the circumferential groove formed on the outer circumferential surface of the holding shaft.

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

[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 onto this hole, and 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 engage the stopper with the radially outer side of multiple points in the center of the C-shaped snap ring to restrict the expansion of the snap ring.

[0018] Also, the stopper can be engaged with one of the bulges at both ends of the snap ring, the bulge that is at the rear in the direction of rotation of the abrasive member.

[0019] With this configuration, the stopper engages with the rear bulge in the direction of rotation, making it easier to attach the snap ring to the circumferential groove than 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 central part 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 polished surface and move rearward in the rotational direction relative to the retaining shaft, the rear end of the snap ring can be forced to move together with the pressure ring, preventing the snap ring from expanding in diameter. In other words, when the front end tries to move together with the pressure ring, the snap ring will not expand in diameter, and when the front end tries to move together with the retaining shaft, only a force acts 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 the impact force. However, the stopper can be prevented from falling off unless it receives a particularly strong impact force before moving rearward and engaging with the rear bulge.

[0022] Also, the stopper may be provided on one of the pair of pressure rings.

[0023] According to this configuration, for example, a stopper can be omitted for the pressure ring on the base end side of the rotating shaft, which is relatively resistant to vibration and where the snap ring is less likely to fall off. Effect 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 peripheral edge of the coated abrasive is moved back and forth in the axial direction of the central axis, so that the surface to be polished can be polished uniformly. Furthermore, since the pressure ring is provided with a stopper, even if the pressure ring that engages with the serpentine shape of the coated abrasive moves in the circumferential direction relative to the holder shaft when the polishing member receives an impact force, the C-shape of the snap ring can be restricted from expanding in diameter, so that the coated abrasive can be formed in a serpentine shape while preventing the snap ring from falling off the holder shaft. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 shows a rotary grinding tool according to the present invention, in which (a) is a front view, (b) the upper half is a right side view, and the lower half is a vertical cross-sectional view. [Diagram 2] An exploded perspective view of a rotary grinding tool [Diagram 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 an AA cross-sectional view, and (c) is a BB cross-sectional view. [Diagram 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] FIG. 1 is a front view of a conventional rotary grinding tool, in which (a) shows the snap ring in a normal state and (b) shows the snap ring in an expanded state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment 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, in a rotary polishing tool 1, a holding shaft 2 attached to a rotating shaft driven by a drive source holds an approximately cylindrical polishing member 3 on its outer periphery, and the polishing member 3 rotates integrally with the holding shaft 2 around its central axis 4, polishing an object to be polished with its peripheral surface. The polishing member 3 is composed of a number of approximately circular abrasive cloth paper 6 having a central hole 5 stacked in the axial direction of the central axis 4, and the holding 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 externally to the holding shaft 2 to hold it in place.

[0028] Furthermore, in the rotary polishing tool 1, the abrasive cloth 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 polishing 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 abrasive cloth 6. Circumferential grooves 9 are formed at both ends of the retaining shaft 2, and C-shaped snap rings 10 are attached to each of the pressure rings 7a, 7b to prevent them from slipping out. One of the pressure rings, the pressure ring 7a, is provided with a stopper 11 that regulates the expansion of the snap ring 10 to prevent it from falling off from 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 circumferential surfaces of both ends, sandwiching the central portion that holds the polishing member 3, so as to continue in the circumferential direction.

[0030] The polishing member 3 comprises 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, with the intermediate portion 15 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 a number of sheets of coated abrasive 6 and clamping and holding 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 fitted onto the holder shaft 2, and flange portions 16b bent on both sides in the axial direction to clamp the peripheral portion of the central hole 5 of the coated abrasive 6. The inner metal fitting 16 is bent into a serpentine shape that reciprocates in the axial direction by pressing a part of it with upper and lower press dies, whereby the peripheral portion of the coated abrasive 6 of the polishing unit 14 is shaped into a serpentine shape.

[0032] The intermediate portion 15 is made by stacking a number of sheets of abrasive cloth 6 in the axial direction, and is clamped in the axial direction between a pair of polishing units 14 so that the sheets conform to the shape of the polishing units 14, causing the peripheral edges of each sheet of abrasive cloth 6 that constitutes this intermediate portion 15 to be shaped in a serpentine shape.

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

[0034] The pressure rings 7a, 7b are ring-shaped with their inner and outer diameters set to be approximately the same as those of the inner metal fitting 16 of the polishing unit 14, and a pressing surface 8 set on the inner surface in the axial direction is formed in a serpentine shape corresponding to the serpentine shape of the inner metal fitting 16. The pressure rings 7a, 7b are disposed on both outer sides 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 the inner peripheral portion of the coated abrasive 6 constituting the polishing member 3 is pressed via the inner metal fitting 16.

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

[0036] Of the snap rings 10 on both sides, for example the snap ring 10 located at the tip end of the rotating shaft is prevented from falling off from the circumferential groove 9 due to expansion in 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 is protruded from the surface opposite to the pressing surface 8 of one of the pressing rings 7a, and is positioned on the outer circumferential side of the snap ring 10 and engages with the bulge portion 17b from the front 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] 5, when the retaining shaft 2 is rotated at high speed in the axial rotation direction 19 to polish the surface to be polished with the peripheral surface of the polishing member 3, if, for example, a foreign object or a protrusion is present on the surface to be polished, the polishing member 3 comes into contact with the foreign object or the protrusion, and an impact force 20 acts on the polishing member 3 backward in the axial rotation direction 19. This impact force 20 causes the pressure ring 7a to become one with the polishing member 3 and to try to shift relative to the retaining shaft 2 in a shifting direction 21 (the opposite direction to the axial rotation direction 19).

[0040] When the pressure ring 7a is shifted in the shift 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. However, the stopper 11 regulates the expansion, thereby 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 is applied between the retaining shaft 2 and 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 portion 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 displacement 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 forcibly moved together 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 embodiment, and appropriate 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 pressing rings 7a, but also on both pressing rings 7a and 7b. The stopper 11 may be engaged not only with the rear bulge 17b in the rotation direction of the grinding member, but also with the front bulge 17a. 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 materials 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 fitting 16a Cylindrical part 16b Flange part 17a, 17b bulge 18 Engagement hole 19 Axis Rotation Direction 20 Impact Force 21 Misalignment direction

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 is ground by a peripheral surface of the grinding member which rotates integrally with the holding shaft around its central axis, The polishing member is formed 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 holder shaft is inserted into the central hole, and a pair of pressure rings fitted to the holder shaft press inner peripheral portions of the number of coated abrasive sheets each having a central hole in the axial direction of the central axis to hold the coated abrasive sheets, 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 peripheral portion of the coated abrasive which is formed by reciprocating the inner peripheral portion of the coated abrasive in the axial direction of the central axis with respect to the circumferential direction of the polishing member, a circumferential groove for receiving a C-shaped snap ring that prevents the pressure ring from slipping out toward the opposite side to the grinding member is formed on the outer peripheral surface of the retaining shaft, and the pressure ring is provided with a stopper that engages with the snap ring to regulate the expansion of the diameter and prevent the pressure ring from falling out of the circumferential groove.

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

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, 2 or 3, wherein the stopper is provided on one of a pair of pressure rings.

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