Grinding machine

Abstract

The invention provides a grinding machine. A polishing machine includes: a polishing unit having a planar sheet placement surface on which a polishing sheet can be placed; and a clamping mechanism capable of holding the polishing sheet on the polishing part. The clamping mechanism is provided with: a clamping part capable of holding the polishing sheet and capable of sliding in a direction parallel to the sheet arrangement surface between a closed position at which the polishing sheet is held on the side surface of the polishing part and an open position at which the polishing sheet can be detached; an elastic body that applies an urging force to the nip portion in a direction parallel to the sheet arrangement surface, the urging force being applied to the nip portion toward the closed position; and a holding mechanism capable of holding the clamp portion in the open position against the biasing force. By releasing the holding of the holding mechanism on the clamping part at the open position, the clamping part can hold the polishing sheet.

Description

Technical Field

[0001] The invention relates to a grinding machine. Background Art

[0002] It is known that there is a grinder having a clamping mechanism for holding a grinding sheet. Japanese Patent Publication No. 2010-207964 describes a grinder having a torsion spring, a clamping lever and a clamping member. A clamping lever is formed at one end of the torsion spring, and the clamping member is connected to the other end of the torsion spring. When the clamping lever is locked to a protruding locking portion by the user while the torsion spring is under a force, the clamping member holds the grinding sheet by the force. Japanese Utility Model Publication No. 2-15256 describes a grinder in which the clamping member is swung up and down by the user operating the clamping lever, thereby holding and releasing the grinding sheet. The clamping member is forced by the torsion spring, so that the clamping member holds the grinding sheet. Summary of the invention

[0003] Regarding the grinder described in Japanese Patent Publication No. 2010-207964, when holding the grinding sheet, the user needs to overcome the force of the torsion spring while lifting the clamping lever to make it stop at the protruding stop portion. Therefore, when the user presses the grinding sheet with his hand while operating the clamping lever, the operability of the clamping lever will be deteriorated. Regarding the grinder described in Japanese Utility Model Publication No. 2-15256, since the torsion spring and the clamping member swing in the vertical direction, the vertical structure of the clamping mechanism will become larger.

[0004] The object of the present invention is to provide an improvement related to the clamping mechanism in a grinding machine.

[0005] According to one non-limiting embodiment of the present invention, there is provided a grinding machine having a grinding section and at least one clamping mechanism. The grinding section has a planar sheet arrangement surface on which a grinding sheet can be arranged. The at least one clamping mechanism can hold the grinding sheet in the grinding section. The at least one clamping mechanism has a clamping section, at least one elastic body, and a holding mechanism. The clamping section can hold the grinding sheet and can slide along a direction parallel to the sheet arrangement surface between a closed position in which the grinding sheet is held on the side of the grinding section and an open position in which the grinding sheet can be removed. At least one elastic body applies a force to the clamping section in a direction parallel to the sheet arrangement surface to the clamping section, which is applied toward the closed position. The holding mechanism can hold the clamping section in the open position against the force. The clamping section can hold the grinding sheet by releasing the holding mechanism of the clamping section at the open position.

[0006] According to this mode, after the user of the grinder sets the grinding sheet in the clamping part held in the open position by the holding mechanism, when the user operates the holding mechanism to release the holding of the clamping part in the open position, the force of the elastic body is added to the force of the user operating the holding mechanism, so that the clamping part moves to the closed position. In this way, the grinding sheet can be held in the clamping part by a simple operation performed by the user. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is the right side view of the grinder.

[0008] Figure 2 It is a longitudinal sectional view of the grinding machine and is a diagram for explaining the outline of the internal structure.

[0009] Figure 3 It is a perspective view showing the front side of the grinder.

[0010] Figure 4 It is a perspective view showing the rear side of the grinder.

[0011] Figure 5 This is an exploded perspective view for explaining the clamping mechanism.

[0012] Figure 6 It is a bottom view showing the cam shifter.

[0013] Figure 7 It is a side view showing the cam shifter.

[0014] Figure 8 It is a top view showing the clamp mechanism and the base in the closed position.

[0015] Fig. 9 It is a top view showing the clamp mechanism and the base in the open position.

[0016] Fig.10 It is an explanatory diagram showing the relationship between the cam portion and the clamp member in the closed position state.

[0017] Fig.11 This is an explanatory diagram showing the relationship between the cam portion and the clamp member when the cam portion rotates in the opening direction starting from the closed position.

[0018] Fig.12 It is an explanatory diagram showing the relationship between the cam portion and the clamp member in the maximum open state.

[0019] Fig.13 It is an explanatory diagram showing the relationship between the cam portion and the clamp member at the rotation stop position.

[0020] Fig.14 2 is a diagram showing the clamp mechanism in a closed position.

[0021] Fig.15 2 is a diagram showing the clamp mechanism in an open position.

[0022] Fig.16 This is a schematic diagram showing a closed position state of a clamp mechanism using a rubber member as an elastic body.

[0023] Fig.17 This is a schematic diagram showing the open position state of a clamp mechanism using a rubber member as an elastic body.

[0024] Fig.18 This is a schematic diagram showing the closed position state of a clamp mechanism using a tension spring as an elastic body.

[0025] Fig.19 This is a schematic diagram showing the open position state of a clamp mechanism using a tension spring as an elastic body.

[0026] Description of Reference Numerals

[0027] 10: grinder; 20: housing; 22: handle; 25: switch; 30: grinding part; 31: grinding pad; 32: base; 40: clamping mechanism; 41: cam shifter; 42: cam part; 43: clamping part; 45: compression spring; 46: rubber part; 47: tension spring; 50: battery installation part; 52: controller; 55: battery; 60: driving mechanism; 61: electric motor; 62: bearing; 63: bearing; 64: bearing; 65: balance member; 66: driving shaft; 71: fan; 72: dust nozzle; 73: foot; 80: handle; 8 2: dust bag; 100: handle mounting portion; 311: sheet configuration surface; 321: boss; 323: cam receiving portion; 324: stopper; 325: elastic body receiving portion; 327: side portion; 328: groove portion; 412: shifting portion; 413: uppermost end; 414: through hole; 415: screw; 431: clamping upper surface portion; 433: spring contact portion; 435: cam contact portion; 437: sheet contact portion; 611: motor shaft; 612: motor body; 661: one end of the drive shaft; A1: drive shaft; PF: pressing force; RF: rotational force. DETAILED DESCRIPTION

[0028] In a non-limiting embodiment of the present invention, the grinder may have a long handle. The direction perpendicular to the sheet arrangement surface is defined as the up-down direction of the grinder, and the direction in which the handle extends when viewed from the up-down direction is defined as the front-back direction of the grinder. The at least one clamping mechanism may include a front clamping mechanism disposed at a position closer to the front side than the center of the grinding portion; the at least one clamping mechanism may also include a rear clamping mechanism disposed at a position closer to the rear side than the center of the grinding portion.

[0029] According to this embodiment, the clamp mechanism is arranged along the same direction as the direction in which the handle extends. Therefore, it is possible to suppress the sander from becoming larger in the left-right direction.

[0030] In addition to the above embodiment, or in place of the above embodiment, the at least one elastic body may be a long spring, and the spring may extend in a direction parallel to the sheet arrangement surface.

[0031] According to this embodiment, since the spring extends in a direction parallel to the sheet arrangement surface, the spring can prevent the clamp mechanism from being enlarged in the vertical direction.

[0032] In addition to the above embodiment, or in place of the above embodiment, the at least one elastic body may be a long compression spring.

[0033] According to this embodiment, compared with a case where another spring such as a torsion spring is disposed in the clamp mechanism as an elastic body, it is possible to suppress an increase in size of the clamp mechanism in the vertical direction.

[0034] In addition to or instead of the above embodiment, the holding mechanism may include a cam portion that abuts against the clamp portion by rotating in the opening direction to thereby press the clamp portion toward the open position.

[0035] According to this embodiment, since the holding mechanism includes the cam portion, the user of the sander can hold the clamp portion in the open position against the urging force of the elastic body without using a large force.

[0036] In addition to or in place of the above-described embodiment, the cam portion can slide the clamping portion to the closed position by rotating in a closing direction opposite to the opening direction. The holding mechanism may include a stopper that stops the rotation of the cam portion in the opening direction at a position where the sliding amplitude of the clamping portion in the direction toward the open position reaches a maximum or the sliding amplitude exceeds the maximum and begins to decrease.

[0037] According to this embodiment, the clamp portion can be held in a state of being largely slid toward the open position by the stopper, so that the user can easily set the polishing sheet.

[0038] In addition to or in place of the above embodiment, the polishing portion may include: at least one receiving portion for receiving the compression spring. The length of each of the at least one receiving portion in the direction in which the compression spring extends may be shorter than the natural length of the compression spring.

[0039] According to this embodiment, during the manufacturing operation of the grinder, when the compression spring is compressed and placed in the receiving portion, the compression spring uses its force to press the inner wall of the receiving portion, thereby fixing the compression spring in the receiving portion, thereby simplifying the manufacturing operation of the grinder.

[0040] In addition to or instead of the above embodiment, the clamping portion may be configured to cover an upper portion of the compression spring accommodated in the at least one accommodation portion.

[0041] According to this embodiment, the compression spring can be protected from external factors.

[0042] In addition to the above embodiment, or in place of the above embodiment, the holding mechanism may include a cam portion that abuts against the clamping portion by rotating in the opening direction, thereby pressing the clamping portion toward the open position. The holding mechanism may include a toggle portion for operating the rotation of the cam portion. The outer contour of the toggle portion when the clamping portion is in the closed position may be located at a position closer to the inside than the outer contour of the sheet arrangement surface in the surface direction.

[0043] According to this embodiment, when working with a grinder, it is possible to suppress the outer contour of the deflector portion from coming into contact with the workpiece or the wall portion rising from the workpiece.

[0044] In addition to the above-mentioned embodiment, or in place of the above-mentioned embodiment, a suction unit for sucking grinding chips generated from the workpiece during grinding by the grinder may be provided. A dust collecting nozzle for discharging the sucked grinding chips toward the rear side of the grinder may be provided. The at least one clamping mechanism may include a rear clamping mechanism arranged at a position further to the rear than the center of the grinding unit. The rear clamping mechanism may be arranged in the lower area of ​​the dust collecting nozzle. The holding mechanism of the rear clamping mechanism may include a cam portion that abuts against the clamping portion by rotating in the opening direction, thereby pressing the clamping portion toward the open position. The holding mechanism of the rear clamping mechanism may include a shifting portion for operating the rotation of the cam portion. The shifting portion may include a portion that becomes higher toward the upper side as it moves away from the rotation axis of the cam portion. The highest portion of the shifting portion may be a height that does not contact the dust collecting nozzle when the cam portion rotates.

[0045] According to this embodiment, the cam portion can be rotated, and the lower region of the dust collecting nozzle can be effectively used, thereby suppressing an increase in the size of the entire sander.

[0046] Below, refer to Figure 1 to Figure 15 , an orbital sander (hereinafter also referred to as a sander 10) according to a non-limiting embodiment of the present invention will be described. The sander 10 illustrated in this embodiment is also referred to as a finish sander.

[0047] Figure 1 As well as Figure 2 As shown, the grinding machine 10 has: a drive shaft 66 (see Figure 2 ), a housing 20 for housing the driving mechanism 60, a polishing unit 30 connected to one end 661 of a driving shaft 66, and a handle 80 mounted on the housing 20. Hereinafter, the central axis of the driving shaft 66 is also referred to as the driving axis A1.

[0048] The grinder 10 further includes a handle 22 connected to the housing 20 and a battery mounting portion 50. The handle 22 extends in a direction intersecting the drive axis A1, and one end of the handle 22 is connected to the housing 20 and the other end is a free end.

[0049] Hereinafter, the direction in which the drive shaft A1 extends is defined as the vertical direction of the grinder 10, the side in the vertical direction where one end 661 of the drive shaft 66 and the grinding part 30 are connected is defined as the lower side, and the opposite side is defined as the upper side. In addition, when viewed from the vertical direction, the direction in which the handle 22 extends is defined as the front-to-back direction of the grinder 10. The free end side of the handle 22 in the front-to-back direction is defined as the rear side, and the opposite side is defined as the front side. In addition, the direction orthogonal to the front-to-back direction and the vertical direction is defined as the left-to-right direction of the grinder 10. In the left-to-right direction, the right side when viewing the front side from the rear side is defined as the right side of the grinder 10, and the opposite side is defined as the left side of the grinder 10.

[0050] The housing 20 forms the outer contour of the sander 10. The front end of the housing 20 forms a handle mounting portion 100 to which the handle 80 is mounted. In the present embodiment, the handle 80 is configured to be attachable to and detachable from the handle mounting portion 100.

[0051] like Figure 2 As shown in FIG. 1 , the driving mechanism 60 includes an electric motor 61. The driving mechanism 60 is configured to drive the grinding unit 30 by the rotational power of the electric motor 61. Figure 2 As shown, in this embodiment, the electric motor 61 is a brushless motor. However, the electric motor 61 can also be a brushed motor.

[0052] The electric motor 61 includes a motor shaft 611 extending in the up-down direction and a motor body 612 having a stator and a rotor. The motor shaft 611 is rotatably supported by bearings 62 and 63 fixed to the housing 20. The motor shaft 611 is configured to be located approximately at the center of the grinding section 30 when viewed from the up-down direction. The lower portion of the motor shaft 611 is connected to the drive shaft 66. The drive shaft 66 is rotatably supported by bearings 62 and 63 fixed to the housing 20. The rotational power of the electric motor 61 is transmitted to the grinding section 30 via the motor shaft 611 and the drive shaft 66. In addition, the rotational power of the electric motor 61 is decelerated by a known power transmission mechanism (not shown) and transmitted to the grinding section 30. In the present embodiment, the rotation axis of the motor shaft 611 coincides with the drive axis A1.

[0053] A fan 71 is installed around the drive shaft 66 and on the lower side of the bearing 63. The fan 71 attracts the grinding chips generated from the workpiece when the grinder 10 grinds. More specifically, a connecting hole connected to the fan 71 is provided on the sheet configuration surface 311. The grinding chips generated from the workpiece when the grinder 10 grinds is attracted from the connecting hole. The storage space of the fan 71 is connected to the dust collecting nozzle 72. The dust collecting nozzle 72 extends toward the rear from the lower side and the rear end of the housing 20. A cloth dust collecting bag 82 for dust collection is connected to the dust collecting nozzle 72. The grinding chips attracted by the fan 71 are discharged from the dust collecting nozzle 72 and retained in the dust collecting bag 82. In addition, a resin dust collecting box (not shown) or a hose (not shown) connected to a dust collector (not shown) can be installed on the dust collecting nozzle 72.

[0054] like Figure 1 to Figure 4 As shown, the grinding part 30 is located at the bottom of the grinding machine 10. The grinding part 30 includes a grinding pad 31 and a base 32. In addition, the grinding part 30 is provided with a clamping mechanism 40 for clamping and fixing the grinding sheet. When viewed from the top and bottom directions, the grinding pad 31 and the base 32 have a roughly rectangular shape with the front-to-back direction as the long side direction. The base 32 is arranged above the grinding pad 31, and the two are connected by bolts extending in the top-to-bottom direction. One clamping mechanism 40 is arranged on the front side and the rear side of the base 32 across the driving mechanism 60. The clamping mechanism 40 arranged at the front side of the base 32 and the clamping mechanism 40 arranged at the rear side of the base 32 have the same structure. As shown in FIG. Figure 4 As shown, the clamping mechanism 40 disposed at the rear side of the base 32 is disposed in the area below the dust collecting nozzle 72. Sandpaper (not shown) as a grinding sheet is mounted on the bottom surface of the grinding pad 31, i.e., the sheet arrangement surface 311, by means of the clamping mechanism 40. The clamping mechanism 40 will be described in detail later.

[0055] like Figure 2 As shown, the grinding part 30 is connected to the drive shaft 66 by means of a bearing 64. Specifically, a balancer 65 is fixed around the lower end of the drive shaft 66. The balancer 65 is fixed to the drive shaft 66 by a bolt screwed into a threaded hole formed at the lower end of the drive shaft 66. The bearing 64 is clamped at a position between the upper part of the balancer 65 and the base 32. The inner ring of the bearing 64 is supported by the lower part of the balancer 65. The bearing 64 is configured in an eccentric state relative to the drive shaft 66. The balancer 65 has a shape in which the center of gravity is offset in a direction opposite to the eccentric direction of the bearing 64 relative to the drive shaft 66. According to this, the generation of vibration caused by the eccentricity of the bearing 64 relative to the drive shaft 66 can be suppressed.

[0056] The grinding part 30 is connected to the housing 20 by means of four legs 73. The legs 73 are configured to suppress vibrations (especially vertical deviations) accompanying orbital motion. In the present embodiment, the legs 73 are respectively arranged near the four corners of the rectangular base 32. The legs 73 have a generally cylindrical shape extending in the vertical direction. The upper end of the legs 73 is engaged with the housing 20 by means of an O-ring. The lower end of the legs 73 is engaged with the base 32 by means of an O-ring. The legs 73 can be tilted relative to the vertical direction while flattening the O-ring.

[0057] The battery mounting portion 50 is disposed at the front side of the handle 22. The battery mounting portion 50 is configured to be able to mount a battery 55 as a power source of the electric motor 61 in a manner that can be slidable in the front-rear direction. Figure 2 As shown, when the battery 55 is mounted on the battery mounting portion 50, the battery 55 is held above the grinding portion 30 and the motor shaft 611. At this time, the motor shaft 611 is located near the center of the battery 55 when viewed from the top and bottom.

[0058] like Figure 2 As shown, a controller 52 is accommodated in the housing 20. In the present embodiment, the controller 52 is arranged at the rear side of the motor body 612 and at the upper side of the dust collecting nozzle 72. The controller 52 is electrically connected to: the terminal provided by the battery mounting portion 50, and the electric motor 61. The controller 52 has various circuits and is configured to control the operation of the electric motor 61 by controlling the power supplied from the battery 55 to the electric motor 61. As the circuit, for example, a high temperature protection circuit, an overcurrent protection circuit, and an over-discharge protection circuit can be listed.

[0059] like Figure 1 , Figure 2 as well as Figure 4 As shown, a switch 25 is provided at the upper front end of the handle 22. The switch 25 is electrically connected to the controller 52. The switch 25 is provided for starting and stopping the electric motor 61.

[0060] <Clamping mechanism configuration>

[0061] Next, refer to Figure 1 to Figure 15 The clamp mechanism 40 will be described. First, the configuration of the clamp mechanism 40 will be described. Then, the function of the clamp mechanism 40 will be described.

[0062] As described above, the clamping mechanism 40 is disposed above the base 32, one on the front side and one on the rear side across the drive mechanism 60. Figure 5 As shown, the clamp mechanism 40 includes a cam stopper 41 , a clamp member 43 , and a compression spring 45 .

[0063] like Figures 5 to 9 As shown, the cam shifter 41 includes a shifter portion 412 and a cam portion 42. In addition, a through hole 414 is formed in the cam shifter 41, through which the cam portion 42 passes. The through hole 414 is penetrated by a screw 415 and screwed with a boss 321 formed on the base 32, so that the cam shifter 41 is fastened to the base 32. The cam shifter 41 can rotate with the boss 321 as a rotation axis. In addition, the boss 321 functions as a cam shaft of the cam portion 42. The shifter portion 412 functions as an operation portion for the user to rotate the cam shifter 41. The cam portion 42 has a function of converting a rotational motion into a linear motion. In addition, the cam portion 42 has a function of converting a force applied from the outside into a rotational force for rotating the cam portion 42 itself. The cam portion 42 is accommodated in a cam accommodation portion 323 having a bottomed hole formed on the base 32.

[0064] like Figure 5 As shown in the figure, an elastic body receiving portion 325 having a bottom hole is formed on the base 32. The compression spring 45 is received in the elastic body receiving portion 325 in a manner extending in the front-to-back direction. The length of the elastic body receiving portion 325 in the front-to-back direction is shorter than the natural length of the compression spring 45. In other words, the natural length of the compression spring 45 is longer than the length of the elastic body receiving portion 325 in the front-to-back direction. That is, the compression spring 45 is received in the elastic body receiving portion 325 in a compressed state.

[0065] The clamping member 43 is arranged on the upper part of the base 32. Specifically, the clamping member 43 is arranged at a position between the cam stopper 41 and the base 32 based on the vertical direction. In the present embodiment, the clamping member 43 is formed by sheet metal processing of a metal plate-shaped member. The clamping member 43 is formed with a clamping upper surface portion 431, a spring contact portion 433, a cam contact portion 435, and a sheet contact portion 437.

[0066] The spring contact portion 433 is formed to extend downward from the clamping upper surface portion 431. Figure 5 , Fig.14 , Fig.15 As shown, the spring contact portion 433 is accommodated in the elastic body accommodation portion 325 and abuts against the compression spring 45. Therefore, the spring contact portion 433 is accommodated in the elastic body accommodation portion 325 in a state where a force is applied from the compression spring 45. Fig.14 , Fig.15In the figure, the blank arrow indicates the force applied by the compression spring 45 to the spring contact portion 433. Specifically, the compression spring 45 applies the force from the outside to the inside of the base 32 to the spring contact portion 433 in the front-to-back direction. More specifically, the compression spring 45 applies the force from the front to the rear to the spring contact portion 433 of the front clamping member 43. The compression spring 45 applies the force from the rear to the front to the spring contact portion 433 of the rear clamping member 43.

[0067] like Fig.14 , Fig.15 As shown, a grinding sheet is sandwiched between the sheet contact portion 437 and the base 32. The sheet contact portion 437 is formed to extend downward from the clamping upper surface portion 431. In addition, the end of the sheet contact portion 437 is in a U-shape bent toward the side portion 327 of the base 32. The force of the compression spring 45 applied to the spring contact portion 433 is transmitted to the sheet contact portion 437 via the clamping upper surface portion 431, so that the sheet contact portion 437 presses the side portion 327 of the base 32. The grinding sheet is clamped by the force of the sheet contact portion 437 pressing the side portion 327 of the base 32.

[0068] like Figure 5 As shown, the cam contact portion 435 is formed to extend downward from the clamping upper surface portion 431 and be received in the cam receiving portion 323. The cam contact portion 435 contacts the cam portion 42 and transmits the rotational force applied to the cam shifter 41 by the user rotating the cam shifter 41 to the clamping member 43 as a force in the front-rear direction.

[0069] The clamping upper surface portion 431 is configured to cover the compression spring 45 accommodated in the elastic body accommodation portion 325 on the upper side of the base 32. By forming such a configuration, the compression spring 45 can be protected from external factors. Specifically, the clamping upper surface portion 431 can protect the compression spring 45 from direct contact with external tools, parts, dust, liquid, etc.

[0070] Next, the function of the clamping mechanism 40 will be described. Figure 8 , Fig.10 , Fig.14 As shown in the figure, the position of the clamping member 43 capable of holding the grinding sheet, the position of the cam shifter 41, and the position of the cam portion 42 are defined as the "closed position". The state of the clamping mechanism 40 when the clamping member 43 is in the closed position is defined as the "closed position state". When the clamping mechanism 40 is in the closed position state, the sheet contact portion 437 abuts against the side surface of the base 32, that is, the side surface portion 327.

[0071] In addition, if Fig. 9 , Fig.13 , Fig.15 As shown in the figure, the position of the clamping member 43, the position of the cam shifter 41 and the position of the cam portion 42, which enable the grinding sheet to be removed, are defined as the "open position". The state of the clamping mechanism 40 when the clamping member 43 is in the open position is defined as the "open position state". When the clamping mechanism 40 is in the open position state, the sheet contact portion 437 is separated from the side surface of the base 32, that is, the side surface portion 327.

[0072] Description: The cam shifter 41 is rotated from the closed position to the open direction. Figure 8 As shown, the toggle portion 412 in the closed position extends in the left-right direction. When viewed from the top-bottom direction, the outer contour of the toggle portion 412 in the closed position is located at a position closer to the inside than the outer contour in the surface direction of the sheet configuration surface 311. More specifically, the outer contour of the toggle portion 412 when the clamping member 43 is in the closed position is located at a position closer to the inside than the outer contours of the left and right side surfaces of the sheet configuration surface 311. Therefore, when the grinder 10 is used for grinding, it is possible to avoid the outer contour of the toggle portion 412 from contacting the workpiece or a portion or wall portion that stands upward from the workpiece. As a result, the user can grind the corner of the workpiece.

[0073] like Fig.10 As shown, when the clamping mechanism 40 is in the closed position, the portion corresponding to the short diameter of the cam portion 42 abuts against the cam contact portion 435. In addition, the spring contact portion 433 is given a force from the outside of the base 32 toward the inside in the front-to-back direction by the compression spring 45. In other words, the compression spring 45 gives the clamping member 43 a force applied toward the closed position. In addition, Fig.10 In the figure, the blank arrows are used to indicate the force applied by the compression spring 45.

[0074] In addition, as described above, the urging force of the compression spring 45 applied to the spring contact portion 433 is transmitted to the sheet contact portion 437 via the clamping upper surface portion 431, so that the sheet contact portion 437 presses the side surface portion 327 of the base 32. The clamping member 43 clamps the polishing sheet by the force of the sheet contact portion 437 pressing the side surface portion 327 of the base 32. The clamping member 43 of the clamping mechanism 40 disposed at both front and rear sides of the base 32 clamps both ends of the polishing sheet in the front and rear direction, so that the polishing sheet can be fixed to the sheet arrangement surface 311.

[0075] In addition, in this embodiment, if Fig.14As shown in FIG. 1 , a groove 328 extending in the left-right direction is formed on the side portion 327. When the clamping mechanism 40 is in the closed position, the end of the sheet contact portion 437 abuts against the groove 328 of the side portion 327. Therefore, in the closed position, compared with a configuration in which the groove 328 is not formed on the side portion 327, the friction between the grinding sheet clamped by the sheet contact portion 437 and the groove 328 can increase the holding force of the grinding sheet by the clamping member 43.

[0076] When the clamp mechanism 40 is shifted from the closed position to the open position, the user operates the shifting portion 412 to rotate the cam shifter 41 toward the outside of the base 32. Hereinafter, the rotation direction of the cam shifter 41 from the closed position to the open position is defined as the opening direction, and the rotation direction of the cam shifter 41 from the open position to the closed position is defined as the closing direction.

[0077] like Fig.11 As shown, when the cam shifter 41 rotates in the opening direction, the cam portion 42 presses the cam contact portion 435 and moves it toward the front-to-back direction of the base 32. The clamping member 43 slides in a direction parallel to the sheet arrangement surface 311. As described above, the compression spring 45 applies the force applied to the clamping member 43 toward the closed position to the clamping member 43. As a result, the cam contact portion 435 of the clamping member 43 applies a pressing force toward the front-to-back direction to the cam portion 42. Hereinafter, the pressing force applied to the cam portion 42 by the cam contact portion 435 due to the force of the compression spring 45 and toward the front-to-back direction is defined as: pressing force PF.

[0078] The pressing force PF is converted into a force in the rotational direction of the cam portion 42 by the cam portion 42. Hereinafter, the force in the rotational direction caused by the pressing force PF and acting on the cam portion 42 is defined as a rotational force RF. Fig.11 In the state shown, a rotational force RF in the closing direction acts on the cam portion 42. When the user rotates the cam shifter 41 in the opening direction, the cam shifter 41 overcomes the rotational force RF in the closing direction and rotates. Fig.11 In FIG. 8 , a dotted line indicates a circle corresponding to the orbit of the major diameter when the cam portion 42 rotates. The rotational force RF acts on the cam portion 42 as a force in the tangential direction of the dotted circle.

[0079] like Fig.12As shown, when the cam portion 42 (cam shifter 41) is further rotated in the opening direction, the state is transferred to the state where the sliding amplitude of the clamping member 43 in the direction toward the open position reaches the maximum. In this state, there is a vector of the pressing force PF on the straight line connecting the contact point where the cam portion 42 abuts against the cam contact portion 435 and the cam shaft. Therefore, the pressing force PF pressed by the cam contact portion 435 on the cam portion 42 is not converted into the rotational force RF that rotates the cam portion 42. Hereinafter, the state of the clamping mechanism 40 at this time is also referred to as the maximum open state. In addition, the positions of the clamping member 43, the cam shifter 41, and the cam portion 42 in the maximum open state are defined as the maximum open position. In this embodiment, the cam shifter 41 in the maximum open position can be further rotated in the opening direction.

[0080] like Fig.13 As shown in FIG. 1 , a stopper 324 is disposed in the cam receiving portion 323. The stopper 324 stops the rotation of the cam portion 42 in the opening direction at a predetermined position. The position where the rotation of the cam portion 42 is stopped by the stopper 324 is defined as a rotation stop position. That is, when the cam portion 42 is rotated toward the opening direction starting from the closed position, the cam portion 42 is located in sequence: the closed position, the maximum open position, and the rotation stop position (open position).

[0081] In this embodiment, when the cam portion 42 (cam shifter 41) is rotated in the opening direction, the stopper 324 stops the rotation of the cam portion 42 in the opening direction at a position where the sliding range of the clamping member 43 in the direction of the open position exceeds the maximum and the sliding range begins to decrease. With such a configuration, even if the user releases his hand from the cam shifter 41 in the rotation stop position, the cam shifter 41 and the clamping member 43 can stably maintain the open position state. This will be described in detail below.

[0082] As described above, the cam portion 42 has the function of converting the pressing force PF of the cam contact portion 435 pressing the cam portion 42 into a rotational force RF for rotating the cam portion 42. Moreover, the direction of the rotational force RF changes with the maximum opening position of the cam portion 42 as a boundary (changing point). More specifically, Fig.11 As shown, when the cam portion 42 is located between the closed position and the maximum open position, the pressing force PF of the cam contact portion 435 pressing the cam portion 42 is converted into a rotational force RF that rotates the cam portion 42 in the closing direction. Fig.13As shown, when the cam portion 42 is between the maximum open position and the rotation stop position, the pressing force PF of the cam contact portion 435 pressing the cam portion 42 is converted into a rotational force RF that rotates the cam portion 42 in the opening direction.

[0083] Therefore, if Fig.13 As shown in FIG. 1 , a rotational force RF that rotates the cam portion 42 in the rotation stop position in the opening direction is applied to the cam portion 42. In addition, the cam portion 42 is stopped from rotating by the stopper 324. As a result, even if the user releases his hand from the cam shifter 41 in the rotation stop position, a rotational force RF that rotates the cam portion 42 in the opening direction is always applied to the cam portion 42 in the rotation stop position, so that the cam shifter 41 and the clamping member 43 can maintain the open position state.

[0084] In addition, a rotational force RF that always rotates the cam portion 42 in the rotation stop position acts on the cam portion 42 in the opening direction. Therefore, even if a force smaller than the rotational force RF that rotates the cam portion 42 in the opening direction acts on the cam shifter 41 from the outside, the cam shifter 41 does not rotate in the closing direction, and the clamping mechanism 40 can maintain the open position state. More specifically, even if a rotational force in the closing direction smaller than the rotational force RF acts on the cam shifter 41, the clamping mechanism 40 can maintain the open position state. That is, by adopting such a configuration, the clamping mechanism 40 can stably maintain the open position state. In addition, the "open position state" in this embodiment is the state of the clamping mechanism 40 (rotation stop state) when the cam portion 42 stops rotating at the rotation stop position by the stopper 324.

[0085] Next, the case where the clamping mechanism 40 is shifted from the open position state (rotation stop state) to the closing direction is described. Fig.15 As shown, when the clamping mechanism 40 is in the open position, that is, when the cam shifter 41 (cam portion 42) is in the rotation stop position, a sufficient distance for inserting the grinding sheet is ensured between the sheet contact portion 437 and the side portion 327. After the grinding sheet is inserted to the position between the sheet contact portion 437 and the side portion 327, the user operates the shifter 412 to rotate the cam shifter 41 toward the closing direction, thereby sliding the clamping member 43 toward the closed position, and clamping the end of the grinding sheet at the position between the sheet contact portion 437 and the side portion 327 (groove portion 328).

[0086] As described above, the direction of the rotational force RF changes with the maximum opening position of the cam portion 42 as a boundary (changing point). Specifically, when the cam portion 42 is located between the closing position and the maximum opening position, the pressing force PF of the cam contact portion 435 pressing the cam portion 42 is converted into the rotational force RF that rotates the cam portion 42 in the closing direction. On the other hand, when the cam portion 42 is located between the maximum opening position and the rotation stop position, the pressing force PF of the cam contact portion 435 pressing the cam portion 42 is converted into the rotational force RF that rotates the cam portion 42 in the opening direction. Therefore, when the user rotates the cam shifter 41 in the rotation stop position in the closing direction, the cam shifter 41 overcomes the rotational force RF that acts on the cam portion 42 and rotates it in the opening direction and rotates until the cam shifter 41 rotates from the rotation stop position to the maximum opening position. Furthermore, when the user rotates the cam shifter 41 in the closing direction and the rotation of the cam shifter 41 exceeds the maximum open position, the direction of the rotational force RF changes, and the pressing force PF is converted into the rotational force RF that rotates the cam portion 42 in the closing direction. The rotational force RF in the closing direction that acts on the cam portion 42 acts in addition to the force that the user applies to the cam shifter 41 in order to rotate the cam shifter 41 in the closing direction. Therefore, the user can rotate the cam shifter 41 in the closing direction to the closed position with a small force.

[0087] In addition, as the cam shifter 41 passes the maximum open position and rotates toward the closing direction, the rotational force RF that rotates the cam portion 42 toward the closing direction increases due to the pressing force PF of the cam contact portion 435 pressing the cam portion 42. Therefore, when the user rotates the cam shifter 41 beyond the maximum open position and toward the closing direction to a predetermined position, the cam shifter 41 can be rotated to the closed position without the user applying force. In addition, in this case, the spring constant of the compression spring 45 needs to be a value greater than a predetermined value. The functions of the clamping mechanism 40 are described above.

[0088] As described above, the grinder 10 of this embodiment includes the cam stopper 41 that can hold the clamping member 43 in the open position against the urging force of the compression spring 45, so that the open position of the clamping member 43 can be held. As a result, the user's work of setting the grinding sheet on the clamping mechanism can be simplified.

[0089] After the user of the grinder 10 places the grinding sheet on the clamping member 43 held in the open position by the cam shifter 41, when the user operates the cam shifter 41 to release the clamping member 43 from being held in the open position, a force due to the pressing force PF is added to the force of the user operating the cam shifter 41 in the closing direction, so that the clamping member moves to the closed position. Thus, the grinding sheet can be held in the clamping member by a simple operation performed by the user and with a small force.

[0090] According to the present embodiment, since the clamp mechanism 40 is disposed at the front and rear positions across the center of the grinding unit 30 , it is possible to suppress the grinding machine 10 from becoming larger in the left-right direction.

[0091] In addition, according to this embodiment, Figure 4 As shown in FIG. 1 , the clamping mechanism 40 disposed at the rear side of the base 32 is disposed in the lower area of ​​the dust collecting nozzle 72. In addition, the detent portion 412 has a portion that becomes higher as it moves away from the rotation axis of the cam portion 42 toward the upper side. The highest portion of the detent portion, i.e., the uppermost end 413 (see FIG. 1 ) Figure 7 ) is configured to reach a height that does not contact the dust collecting nozzle 72 when the cam portion 42 rotates. Therefore, the grinder 10 can rotate the cam portion 42, and by effectively utilizing the lower area of ​​the dust collecting nozzle 72, the overall size of the grinder 10 can be suppressed.

[0092] According to the present embodiment, the compression spring 45 extends in a direction parallel to the sheet arrangement surface 311. Therefore, the compression spring 45 can suppress the sander 10 from being enlarged in the vertical direction.

[0093] According to the present embodiment, the compression spring 45 is used as the elastic body. Therefore, compared with a configuration using other elastic bodies such as a torsion spring, it is possible to suppress an increase in size in the vertical direction.

[0094] According to the present embodiment, the cam shifter 41 (cam portion 42) is used as the holding mechanism. Therefore, the user of the grinder 10 can hold the clamping member 43 in the open position against the force of the compression spring 45 without using a large force.

[0095] According to the present embodiment, the grinding machine 10 includes a stopper 324 that stops the rotation of the cam portion 42 in the opening direction at a position that exceeds a position (maximum open position) where the sliding amplitude of the clamping member 43 in the direction toward the open position reaches a maximum and the sliding amplitude begins to decrease (rotation stop position). Therefore, the clamping member 43 can be kept in a state of sliding greatly toward the open position by the stopper 324, so that the user can easily set the grinding sheet. In addition, even if the user releases his hand from the cam shifter 41, the cam shifter 41 and the clamping member 43 can maintain the open position state.

[0096] Furthermore, a rotational force RF that rotates the cam portion 42 in the rotation stop position acts on the cam portion 42 to rotate in the opening direction. Accordingly, the cam portion 42 stops rotating by the stopper 324. As a result, even if the user releases his hand from the cam shifter 41 in the rotation stop position, the rotational force RF that rotates the cam portion 42 in the rotation stop position always acts on the cam portion 42 in the rotation stop position, so that the cam shifter 41 and the clamping member 43 can maintain the open position state. In addition, a rotational force RF that rotates the cam portion 42 in the rotation stop position always acts on the cam portion 42 in the rotation stop position, so that even if a force smaller than the rotational force RF that rotates the cam portion 42 in the opening direction acts on the cam shifter 41 from the outside, the cam shifter 41 does not rotate in the closing direction, and the clamping mechanism 40 can maintain the open position state. That is, by adopting such a configuration, the open position state of the clamping mechanism 40 can be stably maintained.

[0097] In the present embodiment, the length of the elastic body housing portion 325 in the front-to-back direction is shorter than the natural length of the compression spring 45. In other words, the natural length of the compression spring 45 is longer than the length of the elastic body housing portion 325 in the front-to-back direction. That is, the compression spring 45 is housed in the elastic body housing portion 325 in a compressed state. Therefore, when the clamping mechanism 40 is assembled in the manufacturing process of the grinder 10, the compression spring 45 can be fixed in the elastic body housing portion 325 without using an assembly fixture or the like. On the other hand, when a torsion spring is used in the clamping mechanism, an assembly fixture is often required in order to assemble in a compressed state. Compared with such a structure, the grinder 10 of the present embodiment can simplify the manufacturing operation of the grinder 10 itself.

[0098] In this embodiment, the clamping upper surface portion 431 is configured to cover the compression spring 45 accommodated in the elastic body accommodation portion 325 on the upper side of the base 32. By forming such a configuration, the compression spring 45 can be protected from external factors. Specifically, the clamping upper surface portion 431 can protect the compression spring 45 from direct contact with external tools, parts, dust, liquid, etc.

[0099] Regarding the grinder 10 of this embodiment, when viewed from the top and bottom, the outer contour of the toggle portion 412 in the closed position is arranged at a position closer to the inside than the outer contour of the base 32. More specifically, the outer contour of the toggle portion 412 when the clamping member 43 is in the closed position is located closer to the inside than the outer contour in the surface direction of the sheet arrangement surface 31. Therefore, when the grinder 10 is used for grinding, it is possible to avoid the outer contour of the toggle portion 412 from contacting the workpiece or the part or wall portion that stands upward from the workpiece. As a result, the corner of the workpiece can be ground.

[0100] The correspondence between the components (features) of the above-mentioned embodiment and the components (features) of the present application or the invention is as follows. However, the components of the embodiment are merely examples and do not limit the components of the present application or the invention.

[0101] The grinder 10 is an example of a “grinding machine”. The sandpaper is an example of a “grinding sheet”. The sheet arrangement surface 311 is an example of a “sheet arrangement surface”. The grinding section 30 is an example of a “grinding section”. The clamping mechanism 40 is an example of a “clamping mechanism”. The clamping mechanism 40 arranged at a position closer to the front side than the center of the grinding section 30 is an example of a “front clamping mechanism”. The clamping mechanism 40 arranged at a position closer to the rear side than the center of the grinding section 30 is an example of a “rear clamping mechanism”. The clamping member 43 is an example of a “clamping section”. The compression spring 45 is an example of an “elastic body”. The compression spring 45 is an example of a “spring”. The handle 22 is an example of a “handle”. The cam shifter 41 is an example of a “holding mechanism”. The cam section 42 is an example of a “cam section”. The shifter section 412 is an example of a “shifter section”. The stopper 324 is an example of a “stopper.” The elastic body housing portion 325 is an example of a “housing portion.” The fan 71 is an example of a “suction portion.” The dust collecting nozzle 72 is an example of a “dust collecting nozzle.”

[0102] <Other embodiments>

[0103] Several embodiments of the present invention have been described above, but the above embodiments are for easy understanding of the present invention and do not limit the present invention. The present invention can be changed and improved without departing from its main purpose, and its equivalents are included in the present invention. In addition, the various morphological elements recorded in the claims and the specification can be arbitrarily combined or arbitrarily omitted within the scope of at least a part of the above-mentioned problems or within the scope of at least a part of the effects.

[0104] In the above embodiment, the compression spring 45 is used as the elastic body, but other structures can also be used. For example, a rubber component with elastic force can also be used as the elastic body. Fig.16 As shown in FIG. 1 , a long rubber member 46 is disposed in the elastic body receiving portion 325. The rubber member 46 applies a force to the clamping member 43 in a direction parallel to the sheet arrangement surface 311, thereby applying a force to the clamping member 43 toward the closed position. When the cam lever 41 is rotated toward the open position starting from the closed position, as shown in FIG. Fig.17 As shown, the rubber member 46 is deformed inside the elastic body housing portion 325 to impart a force to the clamping member 43. The rubber member 46 has the same function as the compression spring 45 as an elastic body. Even with such a structure, the same effect as the above embodiment can be obtained. In addition, the clamping mechanism 40 can be manufactured at a lower cost than the above embodiment.

[0105] In the above embodiment, the compression spring 45 is used as the elastic body, but other structures can also be used. For example, a tension spring can also be used as the elastic body. Fig.18 As shown, a long strip-shaped tension spring 47 is arranged in the elastomer housing portion 325. The arrangement position of the tension spring 47 in the elastomer housing portion 325 is different from that in the above-mentioned embodiment. In the present embodiment, a tension spring 47 is arranged in the elastomer housing portion 325 and at a position closer to the center side of the base 32 than the spring contact portion 433. With such an arrangement, the tension spring 47 applies a tensile force (acting force) to the clamping member 43 toward the closed position. The tensile force acts in a direction parallel to the sheet configuration surface 311. When the cam shifter 41 is rotated toward the open position starting from the closed position, as shown in FIG. Fig.19 As shown in FIG. 1 , the rubber member 46 generates a tensile force by stretching inside the elastic body receiving portion 325, and applies a force to the clamping member 43. The rubber member 46 has the same function as the compression spring 45 as an elastic body. In addition, when the tension spring 47 is used as the elastic body, one end of the tension spring 47 needs to be fixed to the elastic body receiving portion 325, and the other end needs to be fixed to the spring contact portion 433.

[0106] In the above-mentioned embodiment, it is also possible to adopt a configuration without the polishing pad 31. In this case, the bottom surface of the base 32 functions as a "sheet placement surface".

[0107] In the above embodiment, it is also possible to adopt a configuration in which the grinder 10 has only one clamping mechanism 40. For example, it is also possible to adopt a configuration in which the clamping mechanism 40 of the present embodiment is provided on the rear side of the base 32, and another clamping mechanism having a configuration different from that of the clamping mechanism 40 of the present embodiment is used on the front side of the base 32. As the other clamping mechanism, a clamping mechanism used in the past can be used. For example, a clamping mechanism using a torsion spring can be used.

[0108] It is also possible to adopt a configuration in which the clamping mechanism 40 is disposed at the left and right sides of the base 32. It is also possible to adopt a configuration in which the clamping mechanism 40 is disposed at the front side, rear side, left side, and right side of the base 32, respectively.

[0109] In the above-mentioned embodiment, the stopper 324 may be arranged at a position where the rotation of the cam portion 42 in the opening direction stops at the maximum open position. In the case of adopting such a structure, the clamping member 43 can be kept in a state of sliding greatly toward the open position by the stopper 324, so that it is easy for the user to set the grinding sheet. As another structure, the stopper 324 may be arranged at a position where the rotation of the cam portion 42 in the opening direction stops at a predetermined position after the sliding range of the clamping member 43 in the direction toward the open position exceeds the maximum and the sliding range begins to decrease when the cam portion 42 (cam shifter 41) rotates in the opening direction. That is, the grinding machine can be configured such that, when the rotation direction of the cam portion that presses the clamping portion toward the open position is defined as the opening direction, and the rotation direction of the cam portion that can slide the clamping portion to the closed position is defined as the closing direction, the holding mechanism includes a stopper that stops the rotation of the cam portion toward the opening direction after the sliding amplitude of the clamping portion in the direction toward the open position exceeds the maximum and begins to decrease. When such a configuration is adopted, even if the user releases his hand from the cam shifter 41, the cam shifter 41 and the clamping member 43 can maintain the open position state. In addition, the clamping member 43 can be kept in a state of sliding greatly toward the open position by the stopper 324, so that the user can easily set the grinding sheet.

[0110] In the above-mentioned embodiment, the clamp mechanism 40 may include only one elastic body. This can be achieved by arranging the elastic body near the center of the clamp mechanism 40 away from the cam portion 42 .

[0111] In the above embodiment, the cam shifter 41 is used as the holding mechanism, but other structures can also be used. For example, a rod-shaped member that can overcome the force of the elastic body and hold the clamping member 43 in the open position can also be arranged in the cam receiving portion 323. The structure is such that when the clamping member 43 is transferred to the open position, the rod-shaped member is clamped between the clamping member 43 (the portion corresponding to the cam contact portion 435) and the wall portion of the cam receiving portion 323 and abuts against each component, and the rod-shaped member overcomes the force of the elastic body and holds the clamping member 43 in the open position. By adopting such a structure, the structure can be simplified.

[0112] The present invention is not limited to the above-mentioned embodiments and other embodiments, and can be implemented in various configurations within the scope of the main purpose. For example, in order to solve part or all of the above-mentioned problems, or to achieve part or all of the above-mentioned effects, the technical features in the embodiments corresponding to the technical features in the various modes described in the column of the invention content can be appropriately replaced or combined. In addition, if it is not stated in this specification that the technical feature is necessary, it can be appropriately deleted.

Claims

1. A grinding machine, characterized in that: The grinding machine comprises: a grinding part having a planar sheet placement surface on which a grinding sheet can be placed; and at least one clamping mechanism capable of holding the grinding sheet in the grinding part. The at least one clamping mechanism comprises: a clamping portion capable of holding the polishing sheet and capable of sliding along a direction parallel to the sheet arrangement surface between a closed position in which the polishing sheet is held on the side of the polishing portion and an open position in which the polishing sheet can be removed; at least one elastic body that imparts a force to the clamping portion in a direction parallel to the sheet arrangement surface, which is applied to the clamping portion toward the closed position; as well as a holding mechanism capable of overcoming the force and holding the clamping portion in the open position, By releasing the holding mechanism of the clamping portion at the open position, the clamping portion can hold the grinding sheet.

2. The grinding machine according to claim 1, characterized in that: The grinder has a long handle. The direction perpendicular to the sheet arrangement surface is defined as the up-down direction of the grinder, and the direction in which the handle extends when viewed from the up-down direction is defined as the front-back direction of the grinder. The at least one clamping mechanism includes: a front clamping mechanism disposed at a position closer to the front side than the center of the polishing portion; and a rear clamping mechanism disposed at a position closer to the rear side than the center of the polishing portion.

3. The grinding machine according to claim 1 or 2, characterized in that: The at least one elastic body is a long strip-shaped spring. The spring extends in a direction parallel to the sheet arrangement surface.

4. The grinding machine according to any one of claims 1 to 3, characterized in that: The at least one elastic body is respectively a long strip-shaped compression spring.

5. The grinding machine according to any one of claims 1 to 4, characterized in that: The holding mechanism includes a cam portion that rotates in an opening direction to come into contact with the clamp portion, thereby pressing the clamp portion toward the open position.

6. The grinding machine according to claim 5, characterized in that: The cam portion is capable of sliding the clamping portion to the closed position by rotating in a closing direction opposite to the opening direction. The holding mechanism includes a stopper that stops the rotation of the cam portion in the opening direction at a position where the sliding range of the clamp portion in the direction toward the open position reaches a maximum or the sliding range exceeds the maximum and starts to decrease.

7. The grinding machine according to claim 4, characterized in that: The polishing part comprises: at least one receiving part for receiving the compression spring; The length of each of the at least one receiving portion in the direction in which the compression spring extends is shorter than the natural length of the compression spring.

8. The grinding machine according to claim 7, characterized in that: The clamping portion is configured to cover an upper portion of the compression spring accommodated in the at least one accommodation portion.

9. The grinding machine according to any one of claims 5 to 8, characterized in that: The holding mechanism includes: a cam portion that abuts against the clamp portion by rotating in the opening direction, thereby pressing the clamp portion toward the open position; and a shifting portion for operating the rotation of the cam portion. When the clamp portion is in the closed position, the outer contour of the deflector portion is located further inward than the outer contour of the sheet arrangement surface in the surface direction.

10. The grinding machine according to any one of claims 5 to 9, characterized in that: The grinding machine comprises: a suction unit for sucking grinding chips generated from a workpiece during grinding by the grinding machine; and a dust collecting nozzle for discharging the sucked grinding chips toward the rear side of the grinding machine. The at least one clamping mechanism comprises: a rear clamping mechanism arranged at a rearward position relative to the center of the polishing part; The rear clamping mechanism is arranged at: the lower area of ​​the dust collecting nozzle, The holding mechanism of the rear clamping mechanism includes: a cam portion that abuts against the clamping portion by rotating in an opening direction, thereby pressing the clamping portion toward the open position; and a shifting portion, which is used to operate the rotation of the cam portion, The deflector portion includes a portion that becomes higher as it moves away from the rotation axis of the cam portion toward the upper side. The highest part of the shifting portion is at a height that does not contact the dust collecting nozzle when the cam portion rotates.

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