Belt sander working part structure, belt sander attachment and belt sander

Abstract

To provide a belt sander working part structure in which a sanding belt is even more difficult to remove, an attachment, and a belt sander.SOLUTION: An attachment, which is a working part of a belt sander, comprises a drive wheel 32 to which a sanding belt B is attached. A belt speed, which is a speed of the sanding belt B, is 8 m / s or less, or can be set to 8 m / s or less. The drive wheel 32 has a drive wheel belt contact part TD which is a part contacting the sanding belt B, and a flange part 222 adjacent to the drive wheel belt contact part TD.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a structure of a working section of a belt sander over which a sanding belt is passed, an attachment for the belt sander, and a belt sander. [Background technology]

[0002] As shown in International Publication No. 2008 / 084265 (Patent Document 1), a grinding and polishing articulated device is known. In this device, an endless belt G for grinding and polishing is wound around a drive roller C, a bearing roller D, and a rotating roller E. The drive roller C is driven by a commercial power source via the plug shown. A rotating roller E is located at the front end. A bearing roller D is located between the drive roller C and the rotating roller E in the front-to-rear direction. In this device, a joint is arranged at the bearing roller D. This device is of a single-joint type. If this device is modified so that the drive roller C also has a joint, the modified device becomes a tandem two-joint type. The tandem two-joint type is a type in which two joints are lined up in the front-to-rear direction.

[0003] Also, as shown in European Patent Application Publication No. 1647362 (Patent Document 2), a bifurcated belt grinder is known. This belt grinder has one joint so that one of the two prongs can move. This belt grinder is a bifurcated, one-joint type. At the ends of the two forks are provided guide rollers 24, 26. At the base of the two forks is provided a drive pulley 22. An endless sanding belt 28 is wound around the drive pulley 22 and the guide rollers 24, 26. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2008 / 084265 [Patent Document 2] European Patent Application Publication No. 1647362 Summary of the Invention [Problem to be solved by the invention]

[0005] In a commercially powered device such as that disclosed in International Publication No. 2008 / 084265 (Patent Document 1), the speed of the endless belt G is high and the drive roller C is provided with a flange. However, in tube belt sanders where the sanding belt speed is slower than a certain level, the drive roller is not provided with a flange. The reason for this is thought to be to prevent the flange from coming into contact with the workpiece. Tube belt sanders where the sanding belt speed is slower than a certain level are tube belt sanders used to sand tubular parts of indoor objects such as handrails. Therefore, in a tube belt sander in which the sanding belt speed is slower than a predetermined level, the sanding belt is relatively likely to come off.

[0006] Furthermore, the height of the flange on the drive pulley 22 in European Patent Application Publication No. 1647362 (Patent Document 2) is not sufficient, and the sanding belt also tends to come off relatively easily.

[0007] Furthermore, in a belt sander, it has been desired to suppress scratches on a workpiece when the flange portion hits the workpiece.

[0008] Therefore, one object of the present disclosure is to provide a structure of a working part of a belt sander, an attachment for a belt sander, and a belt sander that makes it even more difficult for a sanding belt to come off. Another object of the present disclosure is to provide a structure for the working part of a belt sander, an attachment for a belt sander, and a belt sander that suppresses scratches on the workpiece when the flange portion hits the workpiece. [Means for solving the problem]

[0009] This specification discloses a first working unit structure for a belt sander. This first working unit structure may be a working unit structure for performing work on a workpiece in a belt sander. The first working unit structure may include a drive wheel to which a sanding belt is attached. The belt speed, which is the speed of the sanding belt, may be 8 m / s or less or may be settable to 8 m / s or less. The drive wheel may have a belt contact portion that is a portion that comes into contact with the sanding belt. The drive wheel may have a flange portion adjacent to the belt contact portion. This specification also discloses a second working unit structure for a belt sander. This second working unit structure may be a working unit structure for performing work on a workpiece in a belt sander. The second working unit structure may include a drive wheel to which a sanding belt is attached. The drive wheel may have a belt contact portion that is a portion that contacts the sanding belt. The drive wheel may have a flange portion made of synthetic resin adjacent to the belt contact portion. [Effects of the Invention]

[0010] According to the present disclosure, a structure of a working part of a belt sander, an attachment for a belt sander, and a belt sander are provided that make it even more difficult for a sanding belt to come off. Furthermore, the present disclosure provides a structure for the working part of a belt sander, an attachment for the belt sander, and a belt sander that suppresses scratches on the workpiece when the flange portion hits the workpiece. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a left side view of a tube belt sander according to a first embodiment of the present disclosure. FIG. [Figure 2] 2 is an enlarged perspective view of the front part of the tube belt sander of FIG. 1 as seen from the rear. FIG. [Figure 3] FIG. 2 is a perspective view of a drive wheel in the tube belt sander of FIG. 1. [Figure 4]4 is a cross-sectional view of a cross section passing through the center of the drive wheel in the front-rear direction of FIG. 3 and extending in the up-down and left-right directions. [Figure 5] 2 is a cross-sectional view of a first driven wheel of the tube belt sander of FIG. 1, the cross-section passing through the center in the front-rear direction and extending in the up-down and left-right directions. [Figure 6] 2 is a cross-sectional view of a cross section passing through the center in the front-rear direction of a second driven wheel of the tube belt sander of FIG. 1 and extending in the up-down and left-right directions. [Figure 7] FIG. 10 is a perspective view of a drive wheel according to a second embodiment of the present disclosure. [Figure 8] 8 is a cross-sectional view of a cross section passing through the center in the front-rear direction of the drive wheel of FIG. 7 and extending in all directions. [Figure 9] FIG. 10 is a perspective view of a drive wheel according to a third embodiment of the present disclosure. [Figure 10] 10 is a cross-sectional view of a cross section passing through the center of the drive wheel in FIG. 9 in the front-rear direction and extending in all directions. DETAILED DESCRIPTION OF THE INVENTION

[0012] In one embodiment of the present disclosure, the belt contact radius a, which is the distance between the center axis of the drive wheel and the belt contact area, D The flange radius b is the distance between the central axis and the tip of the flange. D The ratio (b D / a D ) may be 1.1 or more. In this case, the sanding belt becomes more difficult to come off. In one embodiment of the present disclosure, the belt contact radius a, which is the distance between the center axis of the drive wheel and the belt contact area, D The flange radius b is the distance between the central axis and the tip of the flange. D The ratio (b D / a D ) may be 1.2 or more. In this case, the sanding belt becomes even more difficult to come off.

[0013] In one embodiment of the present disclosure, the flanges may be provided on both sides of the belt contact portion in the width direction. D From the above, the belt contact radius a, which is the distance between the central axis and the belt contact area, D The value obtained by subtracting this is the flange spacing c D The value divided by ((b D -a D ) / c D ) may be 0.05 or more. In this case, the sanding belt becomes even more difficult to come off. In one embodiment of the present disclosure, the flanges may be provided on both sides of the belt contact portion in the width direction. D From the above, the belt contact radius a, which is the distance between the central axis and the belt contact area, D The value obtained by subtracting this is the flange spacing c D The value divided by ((b D -a D ) / c D ) may be 1.00 or less. In this case, the sanding belt is sufficiently prevented from falling off, and the ease of attaching and detaching the sanding belt is also prevented from decreasing. In one embodiment of the present disclosure, the height of the flange is 3 mm or more, which makes it even more difficult for the sanding belt to come off.

[0014] In one embodiment of the present disclosure, the belt speed of the sanding belt may be set to 3.4 m / s or less, which makes it even more difficult for the sanding belt to come off in a belt sander with a relatively slow belt speed. In one embodiment of the present disclosure, the flange may be made of synthetic resin, which reduces scratches on the workpiece when the flange comes into contact with the workpiece.

[0015] In one embodiment of the present disclosure, the drive wheel may have an outer ring portion that is integral with or separate from the flange portion. In this case, the outer ring portion prevents scratches from being applied to the workpiece. In one embodiment of the present disclosure, the collar may be made of polyamide, which improves the chemical resistance of the collar. In one embodiment of the present disclosure, the outer ring portion may have a rubber belt guide portion. The belt guide portion may be disposed axially inside the flange portion. The belt guide portion may have a belt contact portion. In this case, slippage of the sanding belt relative to the drive wheel is suppressed. In one embodiment of the present disclosure, a part or all of the flange portion may be separate from the outer ring portion, in which case the outer ring portion has a simple structure. In one embodiment of the present disclosure, the belt contact portion may include a tip surface of a plurality of ribs, which reduces slippage of the sanding belt relative to the drive wheel.

[0016] The present specification also discloses an attachment for a belt sander, which may have the working part structure of the belt sander described above. The present specification further discloses a belt sander, which may have the working part structure of the belt sander described above. In one embodiment of the present disclosure, the belt sander may include a brushless motor to drive the drive wheel, making the belt sander lighter, more compact, and more powerful. [Example]

[0017] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. The description includes modified examples of the embodiments. The present disclosure is not limited to the embodiments and modified examples. The front, back, top, bottom, left and right directions in the embodiments and modified examples are defined for the convenience of explanation, and may change depending on at least one of the work situation and the movement of parts.

[0018] [First form] Fig. 1 is a left side view of a tube belt sander 1 according to a first embodiment of the present disclosure, Fig. 2 is an enlarged perspective view of the front part of the tube belt sander 1 as seen from the rear. The tube belt sander 1 has a main body 2 and an attachment 4. The tube belt sander 1 may also be called a pipe belt sander, a tube sander, or a pipe sander. The attachment 4 may also be called an assembly. In the tube belt sander 1, the attachment 4 is a working part that performs work such as sanding on a workpiece. Unlike the tube belt sander 1 described below, the working part may be incorporated into the main body 2 in a state that makes it difficult to separate, i.e., the attachment 4 does not have to be easily detachable from the main body 2. In FIG. 1, the left side is the front of the tube belt sander 1. Also, in FIG. 1, the top side is the top of the tube belt sander 1.

[0019] The main body 2 is cylindrical with its central axis extending in the front-rear direction. The main body 2 has a housing 10, a motor 12, a fan 14, a battery mounting section 16, a battery 18, a controller 20, a connector 22, a speed adjustment dial 24, a main switch 26, a power transmission section 28, and a spindle 30 as an output section. In the main body 2, a battery 18, a battery mounting section 16, a controller 20, a connector 22, a motor 12, a fan 14, a power transmission section 28, and a spindle 30 are arranged in this order from the rear. The battery 18 may not be a component of the main body 2 or the tube belt sander 1, but may be a component independent of the main body 2 or the tube belt sander 1. The spindle 30 may be a component of the power transmission unit 28. The spindle 30 does not have to be a component of the output unit. The output unit may consist only of the drive wheel 32, which is a component of the attachment 4. The drive wheel 32 may be a component of the main body 2.

[0020] The housing 10 forms the outer shell of the main body 2 . The housing 10 directly or indirectly holds various members. The housing 10 includes a motor housing 40, a fan case 42, and a gear housing 44.

[0021] The motor housing 40 is made of plastic. The motor housing 40 is split into two halves, a left motor housing and a right motor housing. The left motor housing and the right motor housing are joined together by screws (not shown) in the left-right direction. The motor housing 40 is cylindrical. The front end of the motor housing 40 forms a front opening that opens forward. The rear end of the motor housing 40 forms a rear opening that opens rearward. The center of the motor housing 40 in the front-rear direction is a grip portion G that can be held by a user.

[0022] The fan case 42 is made of die-cast aluminum alloy and is ring-shaped. The fan case 42 is open at the front and rear.

[0023] The gear housing 44 is made of aluminum die-cast alloy. The gear housing 44 is a bell-shaped member whose front portion is smaller in diameter than its rear portion. The rear end of the gear housing 44 is open to the rear. The gear housing 44 is fixed to the motor housing 40 via the fan case 42. The rear opening of the fan case 42 is aligned with the front opening of the motor housing 40. The rear opening of the gear housing 44 is aligned with the front opening of the fan case 42. The gear housing 44 and the fan case 42 are fixed together with a number of (four) screws 48 that extend forward and backward. The screws 48 are located at the upper right, lower right, upper left, and lower left of the rear of the fan case 42 and the gear housing 44. Each screw 48 is inserted from the front to the rear.

[0024] The housing 10 can be modified in various ways. For example, the front and rear sections of the motor housing 40 may be separate bodies that can be combined with each other. Furthermore, in a split motor housing 40, the left and right motor housings may be significantly different in size and / or shape. Furthermore, the left and right motor housings may be combined using a locking portion such as a pawl and a locking portion such as a pawl hole, rather than by screws. The gear housing 44 may be split in half. The fan case 42 may be omitted by being integrated with the motor housing 40 or the gear housing 44. The materials of various parts of the housing 10 may be changed.

[0025] The motor 12 is a brushless DC motor and serves as a drive source for the drive wheel 32. The motor 12 has a motor shaft 50 and a pinion 52 . The motor shaft 50 rotates around its own central axis and extends in the front-to-rear direction. The pinion 52 is fixed integrally to the front end of the motor shaft 50 .

[0026] The fan 14 is fixed integrally to the motor shaft 50 . The fan 14 is a centrifugal fan. However, other types of fan, such as an axial flow fan, may also be used as the fan 14.

[0027] The battery mounting section 16 is disposed at the rear end of the main body 2. The battery mounting section 16 extends vertically and horizontally relative to the front portion. A battery 18 is attached to the battery attachment section 16. The battery attachment section 16 has a main body side terminal that is connected to a terminal of the battery 18. The main body side terminal is disposed within the rear opening of the main body 2. The battery 18 is attached to the rear side of the battery attachment section 16. The battery 18 is attached by sliding it downward from the top of the battery attachment section 16. The battery 18 may be slid in a direction other than from top to bottom. The battery 18 may also be attached in a manner other than sliding. The battery 18 is a 36V (volt) lithium-ion battery. The battery 18 includes ten cells (not shown) housed in a plastic battery case. The cells are cylindrical and elongated in the axial direction, and face left and right when the battery 18 is installed. The battery 18 holds power for driving the motor 12. Note that any lithium-ion battery with a voltage of 10.8V, 14.4V, 18V, 25.2V, 28V, etc. may be used as the battery 18. Furthermore, a lithium-ion battery with a voltage less than 10.8V or more than 36V may also be used as the battery 18. Other types of batteries may also be used as the battery 18. Multiple batteries 18 may also be used.

[0028] The controller 20 is held inside the battery mounting section 16 . The controller 20 controls the motor 12. The motor 12 is electrically connected to the controller 20 via a connector 22. Furthermore, the main body side terminal of the battery mounting portion 16 is electrically connected to the controller 20. Furthermore, a speed adjustment dial 24 and a main switch 26 are electrically connected to the controller 20.

[0029] The connector 22 is attached to a lead wire (not shown) that connects the motor 12 and the controller 20. The connector 22 can be disconnected to enable reconnection. If only one of the motor 12 and the controller 20 needs to be replaced due to a malfunction or the like, the replacement can be easily performed by disconnecting the connector 22.

[0030] The speed adjustment dial 24 is located at the top of the rear end of the motor housing 40 . The speed adjustment dial 24 extends in all directions and is rotatable around an imaginary axis in the front-rear direction. The upper end of the speed adjustment dial 24 is exposed.

[0031] The main switch 26 is disposed at the upper front end of the motor housing 40 . The top of the main switch 26 is exposed. The main switch 26 is slidable back and forth from a rearward off position to a forward fully on position. When the user slides the main switch 26 forward from the OFF position, the main switch 26 turns ON after a predetermined amount of play. When the main switch 26 is operated further forward from the ON state, the state of the signal it issues may change depending on the amount of forward operation. In this case, the speed adjustment dial 24 may be omitted, and the controller 20 may change the rotation speed of the motor 12 depending on the state of the signal from the main switch 26. The controller 20 may control the motor 12 so that the rotation speed of the motor 12 increases the more the main switch 26 is operated forward. Also, play may be omitted, and the main switch 26 may be set to ON immediately when the main switch 26 begins to be operated forward.

[0032] The power transmission unit 28 transmits the power of the motor 12 to a drive wheel 32 via a spindle 30. The spindle 30 is cylindrical and extends left and right. The power transmission unit 28 has a bevel gear (not shown). The power transmission unit 28 is disposed within a gear housing 44 . The bevel gear meshes with the pinion 52. The bevel gear reduces the rotation speed of the motor shaft 50 and transmits it to the spindle 30 .

[0033] The attachment 4 has a drive wheel 32, a base portion 100, a base portion belt cover 101, a first joint portion 102, a base end arm 104 as an arm connector, a base end arm belt cover 105, a first driven wheel 106, a second joint portion 108, a tip end arm 110 as an arm, a tip end arm belt cover 111, a second driven wheel 114, and a grip 116.

[0034] The drive wheel 32 has a cylindrical shape that extends left and right. The left end of the spindle 30 is located within the center of the right end of the drive wheel 32. The drive wheel 32 is fixed integrally with the spindle 30. The rotation of the spindle 30 is transmitted to the drive wheel 32. The drive wheel 32 rotates around its own central axis. The drive wheel 32 receives the sanding belt B. The sanding belt B is removably mounted on the drive wheel 32. The drive wheel 32 is for mounting the sanding belt B so that it can be driven.

[0035] The base portion 100 is made of metal, more specifically, aluminum die-cast alloy. The base portion 100 has a fixing portion 120 and a bearing portion 122. The fixing part 120 is fixed to the left front end of the gear housing 44 by a left-right screw (not shown). This allows the attachment 4, excluding the drive wheel 32, to be attached to the main body 2. The screw is inserted from left to right. The fixing part 120 is adjacent to the drive wheel 32. The bearing portion 122 is disposed above the fixed portion 120. The bearing portion 122 is bifurcated, with a left protruding portion protruding upward from the left side in a plate-like shape, and a right protruding portion protruding upward from the right side in a plate-like shape. The left protruding portion has a central hole. The right protruding portion has a central hole.

[0036] The base belt cover 101 is made of metal, more specifically steel. The base belt cover 101 has a folded plate shape. The base belt cover 101 is attached to the base 100. The base belt cover 101 covers the rear side of the portion of the sanding belt B that is hung on the drive wheel 32. In other words, the base belt cover 101 covers the sanding belt B on the user side.

[0037] The first joint portion 102 has a shaft body 130, a torsion spring (not shown) which is a base-end side elastic body, and a circlip 134. The torsion spring does not have to be a component of the first joint portion 102, and may be an independent component. The shaft body 130 is cylindrical and extends left and right. The torsion spring is disposed around the shaft 130. The torsion spring is interposed between the base portion 100 and the base-side arm 104. The torsion spring biases the base-side arm 104 to assume a position facing the up-down direction. In other words, the torsion spring biases the base-side arm 104 in a rotational direction from a horizontal position to a vertical position. The circlip 134 is disposed at the left end of the shaft 130 . The first joint portion 102 rotatably connects the base end arm 104 to the base portion 100. The base end arm 104 is rotatably coupled to the base portion 100.

[0038] The base-end arm 104 is made of metal, more specifically, aluminum die-cast alloy. The base-end arm 104 has an arc shape that extends vertically. The base-end arm 104 is curved so as to be convex backward. The base-end arm 104 is located closer to the main body 2 than the tip-end arm 110, i.e., on the base-end side. The base-end arm 104 has a lower bearing portion (not shown), a first driven wheel holding portion (not shown), and an upper bearing portion 146.

[0039] The lower bearing portion is disposed at the lower end of the base end arm 104 . The lower bearing portion has a bifurcated shape, with a left protruding portion protruding downward from the left side portion in a plate-like shape and a right protruding portion protruding downward from the right side portion in a plate-like shape. The left protruding portion has a central hole. The right protruding portion has a central hole. The left protrusion of the lower bearing is disposed to the right of the left protrusion of the base portion 100. The right protrusion of the lower bearing is disposed to the left of the right protrusion of the base portion 100. The central holes of the left protrusion of the lower bearing, the left protrusion of the base portion 100, the right protrusion of the base portion 100, and the right protrusion of the lower bearing are aligned left and right and receive the shaft 130 of the first joint portion 102. The base-end arm 104 is rotatable around the shaft 130 relative to the base portion 100. This allows the attachment 4 to have a first joint. The shaft 130 is prevented from coming off by a circlip 134 on the left side of the left protruding portion. The torsion spring is disposed between the left protruding portion of the lower bearing and the right protruding portion of the lower bearing.

[0040] The first driven wheel holding portion is a hole in the left-right direction and the surrounding area thereof, and is disposed on the upper part of the base end arm 104.

[0041] The upper bearing portion 146 is disposed at the upper end of the base end arm 104 . The upper bearing portion 146 is symmetrical to the lower bearing portion. That is, the upper bearing portion 146 is bifurcated, with a left protruding portion 146L protruding upward from the left side in a plate-like shape, and a right protruding portion 146R protruding upward from the right side in a plate-like shape. The left protruding portion 146L has a central hole. The right protruding portion 146R also has a central hole. The upper bearing portion 146 does not have to be symmetrical to the lower bearing portion.

[0042] The base-side arm belt cover 105 is made of metal, more specifically steel. The base-side arm belt cover 105 is in the shape of a folded plate. The base-side arm belt cover 105 is attached to the base-side arm 104 with a plurality of (two) screws 148 in the left-right direction. The base-side arm belt cover 105 covers the upper and rear sides of the portion of the sanding belt B that is hung on the first driven wheel 106, and the rear side of the portion of the sanding belt B that is stretched between the first driven wheel 106 and the drive wheel 32. In other words, the base-side arm belt cover 105 covers the sanding belt B on the user side.

[0043] The first driven wheel 106 includes a first driven wheel shaft 150, a first driven wheel rotating portion 152, a plurality of bearings 154 (FIG. 5), and a circlip 158. The first driven wheel shaft 150 is a cylindrical pin that extends laterally, and is fixed integrally to a hole in the first driven wheel holding portion. The first driven wheel rotating portion 152 is bobbin-shaped and has an inner hole extending left and right. Each bearing 154 is held by the first driven wheel shaft 150. Each bearing supports the first driven wheel rotation portion 152 so that the first driven wheel rotation portion 152 is rotatable. The circlip 158 is disposed on the left end of the first driven wheel shaft 150. The first driven wheel rotating portion 152 is prevented from coming off by the circlip 158.

[0044] A first driven wheel 106 is carried by the proximal arm 104 . The first driven wheel 106 receives the sanding belt B. The sanding belt B is removably attached to the first driven wheel 106. The first driven wheel 106 is a driven wheel that follows the driven sanding belt B. The first driven wheel 106 is for attaching the sanding belt B.

[0045] The second joint portion 108 has a shaft body 160, a torsion spring 162 which is a tip-end elastic body, and a circlip 164. The torsion spring 162 does not have to be a component of the second joint portion 108, and may be an independent component. The shaft 160 is cylindrical and extends left and right. The torsion spring 162 is disposed around the shaft 160. The torsion spring 162 is interposed between the base-end arm 104 and the tip-end arm 110. The torsion spring 162 biases the tip-end arm 110 so as to open forward and upward relative to the base-end arm 104. In other words, the torsion spring 162 can bias the tip-end arm 110 in a rotational direction so as to open further relative to the base-end arm 104. The circlip 164 is disposed at the left end of the shaft 160 . The second joint 108 rotatably connects the distal arm 110 to the proximal arm 104 .

[0046] The tip-side arm 110 is made of metal, more specifically, aluminum die-cast alloy. The tip-side arm 110 extends in the front-to-rear direction. The tip-side arm 110 has a shape that follows three sides of a trapezoid except for the bottom base. The tip-side arm 110 is bifurcated with its rear end at the base end, and extends forward and upward. The tip-side arm 110 is convex upward. The tip-side arm 110 is located farther from the main body 2 than the base-side arm 104, i.e., on the tip side. The distal arm 110 has a rear bearing portion 170, a second driven wheel holding portion (not shown), and a grip attachment portion 174.

[0047] The rear bearing 170 is disposed at the rear end of the distal arm 110 . The rear bearing portion 170 is bifurcated, with a left protruding portion 170L protruding downward from the left side in a plate-like shape and a right protruding portion 170R protruding downward from the right side in a plate-like shape. The left protruding portion 170L has a central hole. The right protruding portion 170R also has a central hole. The left protrusion 170L is disposed to the left of the left protrusion 146L of the upper bearing 146 of the base-side arm 104. The right protrusion 170R is disposed to the right of the right protrusion 146R of the upper bearing 146 of the base-side arm 104. The central holes of the left protrusion 170L, the left protrusion 146L, the right protrusion 146R, and the right protrusion 170R are aligned laterally and receive the shaft 160 of the second joint 108. The tip-side arm 110 is rotatable around the shaft 160 relative to the base-side arm 104. This allows the attachment 4 to have a second joint. The shaft 160 is prevented from coming off by a circlip 164 on the left side of the left protruding portion 170L. The torsion spring 162 is disposed between the left protruding portion 146L and the right protruding portion 146R of the upper bearing portion 146.

[0048] The second driven wheel holding portion is a hole in the left-right direction and the surrounding area thereof, and is disposed at the front end of the tip-side arm 110. The grip attachment portion 174 is a left-right hole and its surrounding portion, and is disposed at the upper end of the portion of the distal arm 110 that extends upward.

[0049] The distal arm belt cover 111 is made of metal, more specifically steel. The distal arm belt cover 111 is in the shape of a folded plate. The distal arm belt cover 111 is attached to the distal arm 110 with multiple (two) screws 178 in the left-right direction. The distal arm belt cover 111 covers the upper side of the portion of the sanding belt B that is stretched between the second driven wheel 114 and the first driven wheel 106. In other words, the distal arm belt cover 111 covers the sanding belt B on the user side.

[0050] The second driven wheel 114 has a second driven wheel shaft 180, a second driven wheel rotating portion 182, a plurality of (two) bearings 184 (FIG. 6), and a circlip 188. The second driven wheel shaft 180 is a cylindrical pin that extends laterally, and is fixed integrally to a hole in the second driven wheel holding portion. The second driven wheel rotating portion 182 is bobbin-shaped and has an inner hole extending left and right. Each bearing 184 is held by the second driven wheel shaft 180. Each bearing 184 rotatably supports the second driven wheel rotation portion 182. The circlip 188 is disposed on the left end of the second driven wheel shaft 180. The second driven wheel rotating portion 182 is prevented from coming off by the circlip 188.

[0051] The second driven wheel 114 is held by the distal arm 110 . The second driven wheel 114 receives the sanding belt B. The sanding belt B is removably attached to the second driven wheel 114. The second driven wheel 114 is a driven wheel that follows the driven sanding belt B. The second driven wheel 114 is for attaching the sanding belt B.

[0052] The sanding belt B is a belt-shaped, ring-shaped, or endless file. The sanding belt B has an abrasive surface that is used to abrade a workpiece. One sanding belt B is attached to the drive wheel 32, the first driven wheel 106, and the second driven wheel 114 with the sanding surface facing outward. When not sanding, the sanding belt B has a triangular shape with the drive wheel 32, the first driven wheel 106, and the second driven wheel 114 as its vertices when viewed from the left. The sanding belt B receives a driving force from the drive wheel 32 and is fed at a speed that corresponds to the rotational position of the speed adjustment dial 24. In the tube belt sander 1, the feed speed of the sanding belt B, i.e., the belt speed, can be set to 8 m / s (meters per second) or less. The minimum belt speed can be set to 3.4 m / s or less. For example, when the speed adjustment dial 24 is rotated to a position corresponding to the minimum belt speed, the belt speed is set to 3.1 m / s. The tubular belt sander 1, which can be set to a belt speed of 8 m / s or less, is used, for example, to polish tubular parts of indoor objects such as handrails. Also, the tubular belt sander 1, which can be set to a belt speed of 8 m / s or less, is used, for example, to polish mirror surfaces.

[0053] The grip 116 extends to the left and right and can be held by the user. The grip 116 is fixed integrally to the grip attachment portion 174 of the distal arm 110. The grip 116 is disposed on the left side of the grip attachment portion 174.

[0054] The drive wheel 32, the first driven wheel 106, the second driven wheel 114, the distal arm 110, and the proximal arm 104 are elements of a working unit structure P, which is a structure for folding the attachment 4 as a working unit. It should be noted that elements other than those described above may be added to the working unit structure P. Also, in the working unit structure P, some of the elements described above may be omitted.

[0055] Fig. 3 is a perspective view of the drive wheel 32. Fig. 4 is a cross-sectional view of the drive wheel 32, which crosses the center of the drive wheel 32 in the front-rear direction and extends in all directions. The drive wheel 32 has an inner ring portion 200 , an outer ring portion 202 , and a belt guide portion 204 .

[0056] The inner ring portion 200 is made of metal, more specifically, an aluminum alloy. The inner ring portion 200 is cylindrical. The inner ring portion 200 extends in the left and right directions. The inner ring portion 200 has an inner ring bore 210. The inner ring bore 210 is cylindrical and extends left and right. The tip of the spindle 30 is inserted into the inner ring bore 210.

[0057] The outer ring portion 202 is made of synthetic resin, more specifically, polyamide. The outer ring portion 202 is bobbin-shaped. The outer ring portion 202 extends left and right. Because the outer ring portion 202 is made of polyamide, it exhibits chemical resistance. This prevents deterioration of the outer ring portion 202 due to paint component dust generated during the paint removal process. The outer ring portion 202 may or may not contain fibers such as glass fibers. The outer ring portion 202 has an outer ring portion main body 220, an outer ring inner hole 221, a plurality of (two) drive wheel flange portions 222, and a plurality of ribs 224.

[0058] The outer ring portion main body 220 is cylindrical and extends left and right.

[0059] The outer ring inner hole 221 is formed in the center of the outer ring portion main body 220 in the radial direction. The outer ring inner hole 221 is cylindrical and extends laterally. The size of the outer ring inner hole 221 is the same as or approximately the same as the size of the inner ring portion 200. The inner ring portion 200 is inserted into the outer ring inner hole 221. The inner ring portion 200 is fixed in the outer ring inner hole 221.

[0060] Each drive wheel flange 222 is flange-shaped and protrudes radially outward from the left and right ends of the outer ring body 220. Each drive wheel flange 222 is ring-shaped when viewed from the side. The drive wheel flange 222 includes a left drive wheel flange 222L and a right drive wheel flange 222R. The left drive wheel flange 222L is disposed outward from the left end of the outer wheel body 220. The right drive wheel flange 222R is disposed outward from the right end of the outer wheel body 220. The protruding height of the left driving wheel flange 222L is the same as the protruding height of the right driving wheel flange 222R. The protruding height of the left driving wheel flange 222L may be smaller than or larger than the protruding height of the right driving wheel flange 222R. Furthermore, at least one of the left driving wheel flange 222L and the right driving wheel flange 222R may be separate from the outer wheel portion 202.

[0061] Each rib 224 is disposed between each drive wheel flange portion 222 in the left-right direction. Each rib 224 protrudes radially outward from the outer surface of the outer ring portion main body 220 .

[0062] The belt guide portion 204 is integrally molded with the outer ring portion 202. The outer ring portion 202 and the belt guide portion 204 may be fixed to each other by a method other than integral molding. The belt guide 204 is made of rubber and has a cylindrical shape. The belt guide 204 is an elastic body. The belt guide 204 extends to the left and right. The belt guide 204 is disposed on the right side, i.e., on the axially inner side, of the left drive wheel flange 222L. The belt guide 204 is disposed on the left side, i.e., on the axially inner side, of the right drive wheel flange 222R. The belt guide 204 is disposed between each drive wheel flange 222. The belt guide 204 has a belt guide body 230, a belt guide inner hole 232, and a rib 234.

[0063] The belt guide main body 230 is cylindrical and extends left and right. The outer surface of the belt guide body 230 is a drive wheel belt contact portion TD that can come into contact with the sanding belt B. The drive wheel belt contact portion TD bulges outward in the radial direction. The drive wheel belt contact portion TD slopes gently down to both sides in the left-right direction, with a central portion M (FIG. 4) as its apex. This bulging shape is called a "crown." This bulging shape prevents the sanding belt B from shifting outward in the left-right direction from the central portion M of the drive wheel belt contact portion TD. The drive wheel belt contact portion TD is in contact with the inner surface of the sanding belt B. The belt guide portion main body 230 feeds the sanding belt B. Each drive wheel flange 222 is adjacent to the drive wheel belt contact portion TD. Each drive wheel flange 222 is arranged on both sides of the drive wheel belt contact portion TD. Each drive wheel flange 222 is arranged on both sides in the width direction of the drive wheel belt contact portion TD. Each drive wheel flange 222 is arranged on both sides in the width direction of the sanding belt B.

[0064] The belt guide inner hole 232 is formed in the center of the belt guide main body 230 in the radial direction. The belt guide hole 232 is cylindrical and extends laterally. The size of the belt guide hole 232 is the same as or approximately the same as the size of the portion of the outer ring 202 that is laterally inward from each drive wheel flange 222. The outer ring portion 202 is inserted into the belt guide inner hole 232. The outer ring portion 202 is fixed to the belt guide inner hole 232.

[0065] Each rib 234 protrudes radially inward from the inner surface of the belt guide bore 232 . Each rib 234 is integrally formed so as to mesh with each rib 224 of the outer ring portion 202 without any gaps.

[0066] As shown in Figure 4, the virtual center axis ND extending to the left and right of the drive wheel 32 coincides or approximately coincides with the virtual center axis of the inner ring portion 200, the virtual center axis of the outer ring portion 202, and the virtual center axis of the belt guide portion 204. The distance between the center axis ND and the center M of the drive wheel belt contact area TD is the radius a of the drive wheel belt contact area D The center portion M of the drive wheel belt contact portion TD is the portion that is located most radially outward among the portions that contact the sanding belt B. The distance between the center axis ND and the tip of the left drive wheel flange 222L is the radius b DL is equivalent to The distance between the left surface of the right drive wheel flange 222R, i.e., the inner surface in the left-right direction, and the right surface of the left drive wheel flange 222L, i.e., the inner surface in the left-right direction, is the drive wheel flange interval c D is equivalent to

[0067] And the radius of contact of the drive wheel and belt a D Left drive wheel flange radius b DL The ratio (b DL / a D ) may be 1.1 or more. DL / a D corresponds to the relative height of the left drive wheel flange 222L. In this case, the left drive wheel flange 222L sufficiently prevents the sanding belt B from falling off. Also, b DL / a D In this case, the left drive wheel flange 222L can more effectively prevent the sanding belt B from falling off. For example, the radius of contact of the drive wheel and belt a D is 30 mm (millimeters). Left drive wheel flange radius b DL is 38.5 mm. In this case, b DL / a D is (b DL / a D)=1.28, and the sanding belt B is more sufficiently prevented from falling off to the opposite side of the main body portion 2.

[0068] Furthermore, the radius of the left drive wheel flange b DL From the driving wheel belt contact radius a D The value obtained by subtracting (b DL -a D ) Drive wheel flange spacing c D The value divided by (b DL -a D ) / c D may be 0.05 or more. DL -a D corresponds to the height of the left drive wheel flange 222L. In this case, the height of the left drive wheel flange 222L is obtained according to the width of the drive wheel 32, and the left drive wheel flange 222L effectively prevents the sanding belt B from falling off. For example, consider the following case: the radius of contact of the drive wheel and belt a D is 30mm. Left drive wheel flange radius b DL is 38.5 mm. Drive wheel flange spacing c D is 45mm. In this case, (b DL -a D ) / c D is ((b DL -a D ) / c D )=0.189. DL -a D ) / c D is 0.05≦((b DL -a D ) / c D ), the sanding belt B is more sufficiently prevented from falling off to the opposite side of the main body portion 2. Also, (b DL -a D ) / c D may be equal to or less than 1.00. In this case, the effect of the left drive wheel flange portion 222L in preventing the sanding belt B from falling off is sufficiently obtained, and deterioration in workability relating to replacement of the sanding belt B is sufficiently suppressed. For example, the following case, which is different from the above case, is considered: D is 30mm. Left drive wheel flange radius b DL is 38.5 mm. Drive wheel flange spacing c D is 9mm, which is narrower than the above case. In this case, (b DL -a D ) / c D is ((b DL -a D ) / c D )=0.94. DL -a D ) / c D is ((b DL -a D ) / c D )≦1.00, the deterioration of workability in replacing the sanding belt B is sufficiently suppressed.

[0069] Furthermore, (b DL -a D That is, the height of the left drive wheel flange 222L may be 3 mm or more. In this case, the left drive wheel flange 222L can sufficiently prevent the sanding belt B from falling off. Similarly, for the right drive wheel flange 222R, the radius of the right drive wheel flange b DR The radius of the right drive wheel flange b DR may be the distance between the tip of the right driving wheel flange 222R and the center axis ND. DR / a D ) may be set to 1.1 or more, or 1.2 or more. DR -a D ) / c D may be set to 0.05 or more, or 1.00 or less. (b DR -a D That is, the height of the right drive wheel flange 222R may be 3 mm or more. Drive wheel flange radius b D The radius of the left drive wheel flange is b DL and right drive wheel flange radius b DR It may be understood as at least one of the above.

[0070] FIG. 5 is a cross-sectional view of the first driven wheel 106, which crosses the center in the front-rear direction and extends in all directions. The first driven wheel rotating portion 152 of the first driven wheel 106 has a plurality of (two) first driven wheel flange portions 153. Each first driven wheel flange 153 protrudes radially outward from the left-right end of the first driven wheel rotation part 152. Each first driven wheel flange 153 is ring-shaped when viewed from the side. The first driven wheel flange portion 153 includes a left first driven wheel flange portion 153L and a right first driven wheel flange portion 153R. The left first driven wheel flange portion 153L is disposed at the left end portion of the first driven wheel rotating portion 152. The right first driven wheel flange portion 153R is disposed at the right end portion of the first driven wheel rotating portion 152. The protruding height of the left first driven wheel flange portion 153L is the same as or approximately the same as the protruding height of the right first driven wheel flange portion 153R. The protruding height of the left first driven wheel flange portion 153L may be smaller than or larger than the protruding height of the right first driven wheel flange portion 153R. Moreover, at least one of the left first driven wheel flange portion 153L and the right first driven wheel flange portion 153R may be separate from the first driven wheel rotation portion 152.

[0071] Furthermore, a plurality of ribs 155 are erected between the first driven wheel flange portions 153 of the first driven wheel rotation portion 152. Each rib 155 protrudes radially outward in a ring shape. The tip surface of each rib 155 is a first driven wheel belt contact portion T1 that can come into contact with the sanding belt B. Each first driven wheel flange portion 153 is adjacent to the first driven wheel belt contact portion T1. Each first driven wheel flange portion 153 is arranged on both sides of the first driven wheel belt contact portion T1. Each first driven wheel flange portion 153 is arranged on both sides in the width direction of the first driven wheel belt contact portion T1. Each first driven wheel flange portion 153 is arranged on both sides in the width direction of the sanding belt B.

[0072] As shown in FIG. 5, the first driven wheel central axis N1, which is an imaginary central axis extending to the left and right of the first driven wheel rotation portion 152, coincides with or approximately coincides with the imaginary central axes of the bearings 154. The distance between the first driven wheel central axis N1 and the first driven wheel belt contact portion T1 corresponds to the first driven wheel belt contact portion radius a1. The distance between the first driven wheel center axis N1 and the tip of the left first driven wheel flange portion 153L or the right first driven wheel flange portion 153R corresponds to the first driven wheel flange portion radius b1.

[0073] FIG. 6 is a cross-sectional view of the second driven wheel 114, which crosses the center of the second driven wheel 114 in the front-rear direction and extends in all directions. The second driven wheel rotating portion 182 of the second driven wheel 114 has a plurality of (two) second driven wheel flange portions 183. Each second driven wheel flange 183 protrudes radially outward from the left-right end of the second driven wheel rotation portion 182. Each second driven wheel flange 183 is ring-shaped when viewed from the side. The second driven wheel flange portion 183 includes a left second driven wheel flange portion 183L and a right second driven wheel flange portion 183R. The left second driven wheel flange portion 183L is disposed at the left end portion of the second driven wheel rotating portion 182. The right second driven wheel flange portion 183R is disposed at the right end portion of the second driven wheel rotating portion 182. The protruding height of the left second driven wheel flange portion 183L is the same as or approximately the same as the protruding height of the right second driven wheel flange portion 183R. The protruding height of the left second driven wheel flange portion 183L may be smaller than or larger than the protruding height of the right second driven wheel flange portion 183R. Furthermore, at least one of the left second driven wheel flange portion 183L and the right second driven wheel flange portion 183R may be separate from the second driven wheel rotation portion 182.

[0074] Furthermore, a plurality of ribs 185 are erected between the second driven wheel flange portions 183 of the second driven wheel rotation portion 182. Each rib 185 protrudes radially outward in a ring shape. The tip surface of each rib 185 is a second driven wheel belt contact portion T2 that can come into contact with the sanding belt B. Each second driven wheel flange portion 183 is adjacent to the second driven wheel belt contact portion T2. ​​Each second driven wheel flange portion 183 is arranged on both sides of the second driven wheel belt contact portion T2. ​​Each second driven wheel flange portion 183 is arranged on both sides in the width direction of the second driven wheel belt contact portion T2. ​​Each second driven wheel flange portion 183 is arranged on both sides in the width direction of the sanding belt B.

[0075] As shown in FIG. 6, the second driven wheel central axis N2, which is an imaginary central axis extending laterally of the second driven wheel rotation portion 182, coincides with or substantially coincides with the imaginary central axes of the bearings 184. The distance between the second driven wheel central axis N2 and the second driven wheel belt contact portion T2 corresponds to the second driven wheel belt contact portion radius a2. The distance between the second driven wheel central axis N2 and the tip of the left second driven wheel flange portion 183L or the right second driven wheel flange portion 183R corresponds to the second driven wheel flange radius b2.

[0076] The tube belt sander 1 is, for example, a b D / a D, b1 / a1 of the first driven wheel 106, and b2 / a2 of the second driven wheel 114 can be configured so that one of them is 1.2 or more, and the remaining two are less than 1.2. In this case, the sanding belt B can be easily replaced while still being able to sufficiently prevent the sanding belt B from falling off. The structure of the working part of the belt sander, including this case, will now be disclosed again. (1) A structure of a working part for performing work on a workpiece in a belt sander, It has three or more wheels to fit one sanding belt. Each wheel has a belt contact portion that contacts the sanding belt and flange portions that are disposed on both sides of the belt contact portion, In any one of the wheels, the ratio (b / a) of the wheel radius (b), which is the distance from the tip of the flange portion to the central axis, to the belt contact portion radius (a), which is the distance from the belt contact portion to the central axis of the wheel, is 1.2 or more; In the other two or more wheels, the ratio (b / a) of the wheel radius (b), which is the distance from the tip of the flange to the central axis, to the belt contact radius (a), which is the distance from the belt contact portion to the central axis of the wheel, is less than 1.2. 1. A working part structure of a belt sander.

[0077] In addition, the tube belt sander 1 has, for example, a b D / a D is greater than or equal to 1.2, b1 / a1 at the first driven wheel 106 is less than 1.2, and b2 / a2 at the second driven wheel 114 is less than 1.2. In this case, the sanding belt B can be easily replaced while still being able to sufficiently prevent the sanding belt B from falling off. The structure of the working part of the belt sander, including this case, will now be disclosed again. (2) A structure of a working part for performing work on a workpiece in a belt sander, The sanding belt has a drive wheel and first and second driven wheels for mounting thereon, the drive wheel has a drive wheel belt contact portion that contacts the sanding belt and drive wheel flange portions that are disposed on both sides of the drive wheel belt contact portion, the first driven wheel has a first driven wheel belt contact portion that contacts the sanding belt and first driven wheel flange portions that are disposed on both sides of the first driven wheel belt contact portion, the second driven wheel has a second driven wheel belt contact portion that contacts the sanding belt and second driven wheel flange portions that are disposed on both sides of the second driven wheel belt contact portion, The drive wheel belt contact radius (a D ) the radius of the drive wheel (b D ) ratio (b D / a D ) is 1.2 or more, In the first driven wheel, a ratio (b1 / a1) of a first driven wheel radius (b1) that is a distance from a tip of a flange portion of the first driven wheel to the central axis of the first driven wheel to a first driven wheel belt contact portion radius (a1) that is a distance from the first driven wheel belt contact portion to the central axis of the first driven wheel is less than 1.2, In the second driven wheel, a ratio (b2 / a2) of a second driven wheel radius (b2) which is the distance from the tip of the second driven wheel flange to the central axis of the second driven wheel to a second driven wheel belt contact radius (a2) which is the distance from the second driven wheel belt contact portion to the central axis of the second driven wheel is less than 1.2. 1. A working part structure of a belt sander.

[0078] An example of the operation of such a tube belt sander 1, attachment 4, and working unit structure P will be described. The user attaches a charged battery 18 to the battery attachment section 16 of the main body 2. The user attaches the attachment 4 to the main body 2. The user locks the attachment 4. The user attaches the sanding belt B to the attachment 4. When the user operates the main switch 26, the main switch 26 is turned on. Then, the controller 20 controls and supplies power from the battery 18 to the motor 12 so that the motor shaft 50 rotates at a speed corresponding to the rotation position of the speed adjustment dial 24. As a result, the motor 12 is driven at a speed corresponding to the rotation position of the speed adjustment dial 24. The rotation direction of the motor shaft 50 may be switchable.

[0079] Rotation of the motor shaft 50 rotates the fan 14, and air is exhausted to an exhaust port (not shown), thereby creating an air flow (wind) within the main body 2. Such wind cools the internal mechanisms of the tube belt sander 1, including the motor 12.

[0080] Furthermore, the rotational force of the motor shaft 50 is transmitted to the spindle 30 and the drive wheel 32 after being reduced in speed by a bevel gear. The drive wheel 32 feeds the sanding belt B. The sanding belt B rotates in a continuous track manner around the drive wheel 32, the first driven wheel 106, and the second driven wheel 114. The belt speed can be set to 8 m / s or less by using the speed adjustment dial 24. The belt speed can also be set to 3.4 m / s or less by using the speed adjustment dial 24. The belt speed may be set to 8 m / s or less regardless of the rotation position of the speed adjustment dial 24, i.e., the operating state of the speed adjustment dial 24. The belt speed may be set to 3.4 m / s or less regardless of the rotation position of the speed adjustment dial 24, i.e., the operating state of the speed adjustment dial 24. Furthermore, the speed adjustment dial 24 may be omitted, and the belt speed may always be a predetermined value of 8 m / s or less. Furthermore, the speed adjustment dial 24 may be omitted, and the belt speed may always be a predetermined value of 3.4 m / s or less.

[0081] The user holds the grip portion G of the main body portion 2 with his right hand and the grip 116 of the attachment 4 with his left hand. Then, the user places the underside of the portion of the sanding belt B between the drive wheel 32 and the second driven wheel 114 against the portion of the workpiece to be processed, such as the outer surface of a pipe. The portion of the workpiece to be processed is then polished by the sanding belt B.

[0082] At this time, the route of the sanding belt B between the drive wheel 32 and the second driven wheel 114 is depressed upward along the workpiece in a "U" shape when viewed from left to right, depending on the pressing force against the workpiece. When this depression occurs in the route of the sanding belt B, the route of the sanding belt B changes from a triangular shape to a square shape. This depression in the route of the sanding belt B allows the workpiece to be enveloped by the sanding belt B. This allows for better polishing of the workpiece. Since the length of the sanding belt B does not change, the second driven wheel 114 moves closer to the drive wheel 32 by the amount of the recess in the root of the sanding belt B. The second driven wheel 114 moves closer to the drive wheel 32 mainly by the rotation of the distal arm 110 relative to the proximal arm 104. The rotation of the distal arm 110 relative to the proximal arm 104 is performed in a state where the torsion spring 162 acts elastically. Furthermore, the base end arm 104 rotates relative to the base portion 100 in a state where the torsion spring of the first joint portion 102 acts elastically.

[0083] The tube belt sander 1 is a two-joint type having a first joint 102 and a second joint 108 at the front and rear, which are rotatable in an elastic state, and therefore the sanding belt B contacts the workpiece better than a one-joint type without the first joint 102. Therefore, the tube belt sander 1 can sand the workpiece better. Next, the structure of the working part of the belt sander relating to the tandem two-joint type will be disclosed again. (3) A structure of a working part for performing work on a workpiece in a belt sander, a drive wheel and a plurality of driven wheels for mounting a sanding belt; a base portion fixed to a main body portion adjacent to the drive wheel; a base end arm rotatably connected to the base portion; a distal arm rotatably coupled to the proximal arm and carrying one or more of the driven wheels; Equipped with 1. A working part structure of a belt sander. (4) In the working part structure of the belt sander of (3), a distal end elastic body that can bias the distal end arm in one rotational direction relative to the base end arm; a base-end elastic body that can bias the base-end arm in one rotational direction relative to the base portion; Equipped with 1. A working part structure of a belt sander.

[0084] Furthermore, during sanding, the sanding belt B is prevented from falling off to the left by the left drive wheel flange 222L of the drive wheel 32. Also, the sanding belt B is prevented from falling off to the right by the right drive wheel flange 222R of the drive wheel 32. Such a function of preventing sanding belt B from falling off is sufficient even when the belt speed is 8 m / s or less. Such a function of preventing sanding belt B from falling off is sufficient even when the minimum settable value of the belt speed is 3.4 m / s or less. In particular, when processing a workpiece portion that is curved convexly relative to the sanding belt B, the tube belt sander 1 sufficiently prevents the sanding belt B from falling off compared to a tube belt sander with a drive wheel without a flange. If the belt speed is slower than a predetermined level, the tension of the sanding belt B becomes relatively weak, and the sanding belt B becomes more likely to twist during processing, making it more likely to come off. However, in the tube belt sander 1, the drive wheel flange portion 222 effectively prevents the sanding belt B from coming off.

[0085] The user can change the way the sanding belt B contacts the processed part, that is, the position and range where the sanding belt B contacts the processed part, depending on the overall shape of the processed part.

[0086] When sanding is complete, the user stops sliding the main switch 26 forward to turn off the motor 12. At this time, the sanding belt B stops. The user then removes the sanding belt B, attachment 4, and battery 18 as appropriate.

[0087] The embodiments of the present disclosure are not limited to the above and the modified examples, and further modifications such as those described below can be made as appropriate. The various flanges may be provided only on the left or right side. Some or all of the flanges of the drive wheel may be omitted. Some or all of the flanges of the various driven wheels may be omitted. The drive wheel belt contact portion TD does not have to bulge outward in the radial direction. For example, the drive wheel belt contact portion TD may be flat, or may have an uneven surface formed by a plurality of ribs protruding outward in the radial direction. At least one of the distal elastic body and the proximal elastic body may be other than a torsion spring.

[0088] The speed reduction mechanism from the motor shaft 50 to the drive wheel 32 in the tube belt sander 1 may be replaced with a speed reduction mechanism other than the pinion 52 and bevel gear. The tube belt sander 1 may be AC-powered by a commercial power source by having a power cord instead of the battery mounting portion 16. At least one of the materials of the various cases and housings may be changed to resin, metal, a composite of these, etc. The classification of the housing 10 may be changed from that described above. In addition, at least one of the various members, the number of parts, whether or not they are installed, the material, arrangement, structure, and type may be changed as appropriate.

[0089] Furthermore, the above embodiment or its modified example may be applied to other tube belt sanders. For example, the above embodiment or its modified example may be applied to a single-joint type tube belt sander. The single-joint type tube belt sander may be a bifurcated, single-joint type. In the case of a bifurcated, single-joint type, the base of the bifurcated part may be foldable by a switching means. Alternatively, the above embodiment or its modified example may be applied to a tube belt sander having three or more driven wheels. Alternatively, the above embodiment or its modified example may be applied to a tube belt sander having multiple drive wheels. Alternatively, the above embodiment or its modified example may be applied to a tube belt sander having three or more joints. Alternatively, the above embodiment or its modified example may be applied to other belt sanders. The other belt sander is, for example, a file belt sander.

[0090] [Second form] Fig. 7 is a perspective view of a drive wheel 300 in a tube belt sander according to a second embodiment of the present disclosure. Fig. 8 is a cross-sectional view of the drive wheel 300, passing through the center in the front-rear direction and extending in all directions. The second embodiment is similar to the first embodiment except for the drive wheel. The same parts of the second embodiment as those of the first embodiment are appropriately designated by the same reference numerals as those of the first embodiment, and the description thereof will be omitted.

[0091] The drive wheel 300 of the second form has an inner ring portion 200 and an outer ring portion 302 . The outer ring portion 302 is made of synthetic resin, more specifically polyamide. The outer ring portion 302 is bobbin-shaped. The outer ring portion 302 extends left and right. The outer ring portion 302 has an outer ring portion main body 320, an outer ring inner hole 221, a plurality of (two) drive wheel flange portions 222, and a plurality of ribs 324.

[0092] The outer ring portion main body 320 is cylindrical and extends left and right. Each rib 324 is disposed between each drive wheel flange portion 222 in the left-right direction. Each rib 324 protrudes radially outward from the outer surface of the outer ring portion main body 220 . Each rib 324 is ring-shaped when viewed from left to right. The ribs 324 are lined up on the left and right. Unlike the first embodiment, the outer ring portion main body 320 and each rib 324 are exposed to the outside.

[0093] The portion of the outer ring portion 302 between the left and right drive wheel flange portions 222 has projections and recesses due to the ribs 324. The projections and recesses are formed by the ribs 324. The tip end surface of each rib 324, that is, the surface positioned at the outermost position in the radial direction, becomes a drive wheel belt contact portion TD with which the sanding belt B comes into contact. The sanding belt B is fed by the drive wheel belt contact portion TD associated with the unevenness, so that slippage of the sanding belt B on the drive wheel 300 is suppressed.

[0094] In the second embodiment of the driving wheel 300, the driving wheel belt contact radius a D Drive wheel flange radius b D The ratio (b D / a D ) is 1.1 or more, or 1.2 or more, the driving wheel flange portion 222 can sufficiently suppress the sanding belt B from falling off. Furthermore, in the second type of drive wheel 300, (b D -a D ) / c D If the value is 0.05 or more, the height of the left drive wheel flange 222L is obtained according to the width of the drive wheel 32, and the drive wheel flange 222 sufficiently prevents the sanding belt B from falling off. Also, in the second type of drive wheel 300, (b D -a D ) / c D If the ratio is 1.00 or less, the drive wheel flange portion 222 can sufficiently prevent the sanding belt B from falling off, and deterioration in workability for replacing the sanding belt B can be sufficiently prevented. Furthermore, in the second embodiment of the drive wheel 300, if the height of the drive wheel flange 222 is set to 3 mm or more, the drive wheel flange 222 can sufficiently prevent the sanding belt B from falling off.

[0095] The second embodiment has the same modifications as the first embodiment, as appropriate. Furthermore, at least one of the ribs 324 does not have to be ring-shaped when viewed from left to right. The ribs 324 do not have to be aligned side by side. The number of ribs 324 may be increased or decreased from the number shown in the figure.

[0096] [Third form] Fig. 9 is a perspective view of a drive wheel 400 in a tube belt sander according to a third embodiment of the present disclosure. Fig. 10 is a cross-sectional view of the drive wheel 400, passing through the center in the front-rear direction and extending in all directions. The third embodiment is similar to the first embodiment except for the drive wheel. The same parts of the third embodiment as those of the first embodiment are appropriately designated by the same reference numerals as those of the first embodiment, and the description thereof will be omitted.

[0097] The drive wheel 400 of the third embodiment has an outer ring portion 402, a belt guide portion 404, and a plurality of (two) cover portions 406. The outer ring portion 402 is made of synthetic resin, more specifically, polyamide. The outer ring portion 402 is bobbin-shaped. The outer ring portion 402 extends in the left and right directions. The outer ring portion 402 has an outer ring portion main body 420, an outer ring inner hole 421, a plurality (two) of drive wheel flange base portions 422, and a plurality (three) of screw holes 424.

[0098] The outer ring portion main body 420 is cylindrical and extends left and right. The outer ring portion main body 420 integrally includes the inner ring portion 200 in the first form. The outer ring inner hole 421 is configured similarly to the inner ring inner hole 210 of the first embodiment. The left drive wheel collar base 422 protrudes radially outward from the left end of the outer ring portion body 420. The right drive wheel collar base 422 protrudes radially outward from the right end of the outer ring portion body 420. Each screw hole 424 extends left and right and penetrates the outer ring portion main body 420. The left and right ends of each screw hole 424 are enlarged relative to the inner portions in the left and right direction.

[0099] The belt guide portion 404 is integrally molded with the outer ring portion 402. The outer ring portion 402 and the belt guide portion 404 may be fixed to each other by a method other than integral molding. The belt guide 404 is made of rubber and has a cylindrical shape. The belt guide 404 is an elastic body. The belt guide 404 extends to the left and right. Belt guides 404 are disposed between each of the drive wheel collar bases 422 . The belt guide 404 has a belt guide body 430 and a belt guide inner hole 432 .

[0100] The belt guide main body 430 is cylindrical and extends left and right. The outer surface of the belt guide body 430 is a drive wheel belt contact portion TD that can come into contact with the sanding belt B. The drive wheel belt contact portion TD bulges outward in the radial direction. In the left-right direction, the drive wheel belt contact portion TD slopes gently downward to both sides, with a central portion M (FIG. 10) as its apex. The drive wheel belt contact portion TD is in contact with the inner surface of the sanding belt B. The belt guide portion main body 430 feeds the sanding belt B. Each drive wheel flange base 422 is adjacent to the drive wheel belt contact portion TD. Each drive wheel flange base 422 is arranged on both sides of the drive wheel belt contact portion TD. Each drive wheel flange base 422 is arranged on both sides in the width direction of the drive wheel belt contact portion TD. Each drive wheel flange base 422 is arranged on both sides in the width direction of the sanding belt B.

[0101] The belt guide inner hole 432 is formed in the center of the belt guide main body 430 in the radial direction. The belt guide hole 432 is cylindrical and extends laterally. The size of the belt guide hole 432 is the same as or approximately the same as the size of the portion of the outer ring 402 that is inward in the left-right direction from each drive wheel flange base 422. The outer ring portion 402 is inserted into the belt guide portion inner hole 432. The outer ring portion 402 is fixed to the belt guide portion inner hole 432.

[0102] Each cover portion 406 is made of synthetic resin and has a ring-like plate shape that extends in all directions. The cover portions 406 are arranged symmetrically to one another. Hereinafter, the left cover portion 406 will be described as a representative example. The cover portion 406 has a cover portion main body 440, a central hole 442, a plurality of (three) screw holes 444, and a peripheral portion 446.

[0103] The cover body 440 is in the shape of a ring plate. The central hole 442 is opened in the center of the cover body 440. When viewed from left to right, the outer ring inner hole 421 is located radially inward of the central hole 442. Each screw hole 444 is drilled around the central hole 442. The screw holes 444 are arranged on an imaginary circle and lined up in the circumferential direction. When viewed from left to right, the corresponding screw hole 424 of the outer ring portion 402 is located radially inward of the screw hole 444. The periphery of each screw hole 444 is formed in a shape corresponding to the enlarged portion of the screw hole 424, and is located within the enlarged portion of the screw hole 424. The peripheral edge portion 446 is disposed on the outer periphery of the cover body 440. The peripheral edge portion 446 is ring-shaped when viewed from left to right. The peripheral edge portion 446 is bent inward in the left-right direction relative to the cover body 440. The peripheral edge portion 446 runs along the upper side and the outer side in the left-right direction of the drive wheel flange base 422.

[0104] The left cover portion 406 is fixed to the left side of the outer ring portion 402 by inserting a plurality of (three) screws 408 into the corresponding screw holes 444 and the left part of the screw holes 424 . The right cover portion 406 is fixed to the right side of the outer ring portion 402 by inserting a plurality of (three) screws 408 into the corresponding screw holes 444 and the right part of the screw holes 424 .

[0105] In the drive wheel 400, the drive wheel flange base 422 and the peripheral edge 446 form a drive wheel flange 448. In this case, a part of the drive wheel flange 448 is separate from the outer ring 402. When a part of the drive wheel flange 448 is separated from the outer ring 402 in this way, the outer ring 402 has a simple structure.

[0106] In the third embodiment of the driving wheel 400, the driving wheel belt contact radius a D Drive wheel flange radius b D The ratio (b D / a D) is 1.1 or more, or 1.2 or more, the driving wheel flange portion 448 can sufficiently suppress the sanding belt B from falling off. Furthermore, in the third type of drive wheel 400, (b D -a D ) / c D If the value is 0.05 or more, the height of the left drive wheel flange 448L is obtained according to the width of the drive wheel 32, and the drive wheel flange 448 sufficiently prevents the sanding belt B from falling off. Also, in the third form of the drive wheel 400, (b D -a D ) / c D If the ratio is 1.00 or less, the drive wheel flange portion 448 can sufficiently prevent the sanding belt B from falling off, and deterioration in workability for replacing the sanding belt B can be sufficiently prevented. Furthermore, in the third embodiment of the drive wheel 400, if the height of the drive wheel flange 448 is set to 3 mm or more, the drive wheel flange 448 can sufficiently prevent the sanding belt B from falling off.

[0107] The third embodiment has the same modifications as the first and second embodiments as appropriate. Alternatively, the drive wheel flange 448 may be formed only by the peripheral edge 446 of the cover 406. In this case, the entire drive wheel flange 448 is separate from the outer ring 402. [Explanation of symbols]

[0108] 1··Tube belt sander (belt sander), 4··Attachment (working part), 12··Motor (brushless motor), 32, 300, 400··Drive wheel, 200··Inner ring part, 202, 302, 402··Outer ring part, 204, 404··Belt guide part, 222, 448··Drive wheel flange part (flange part), 422··Drive wheel flange base (part of flange part), 446··Peripheral part (part of flange part), B··Sanding belt, P··Working part structure (which prevents the sanding belt from falling off), TD··Drive wheel belt contact part (belt contact part), a DDrive wheel-belt contact radius (belt contact radius), b D Drive wheel flange radius (flange radius), c D ··Drive wheel flange spacing (flange spacing).

Claims

1. A structure of a working part for performing work on a workpiece in a belt sander, Drive wheel onto which the sanding belt is attached It is equipped with The belt speed of the sanding belt is 8 m / s or less, or can be set to 8 m / s or less, The drive wheel has a belt contact portion that is a portion that comes into contact with the sanding belt, and a flange portion adjacent to the belt contact portion.

1. A working part structure of a belt sander.

2. The belt contact radius a is the distance between the center axis of the drive wheel and the belt contact area. Ｄ The flange radius b is the distance between the central axis and the tip of the flange. Ｄ The ratio (b Ｄ / a Ｄ ) is 1.1 or more 2. The working part structure of a belt sander according to claim 1.

3. The belt contact radius a is the distance between the center axis of the drive wheel and the belt contact area. Ｄ The flange radius b is the distance between the central axis and the tip of the flange. Ｄ The ratio (b Ｄ / a Ｄ ) is 1.2 or more 2. The working part structure of a belt sander according to claim 1.

4. The flanges are provided on both sides of the belt contact portion in a width direction, The flange radius b is the distance between the center axis of the drive wheel and the tip of one of the flanges. Ｄ From the above, the belt contact radius a, which is the distance between the central axis and the belt contact portion, Ｄ The value obtained by subtracting 1 is the flange interval c, which is the distance between the two flanges. Ｄ The value divided by ((b Ｄ -a Ｄ ) / c Ｄ ) is 0.05 or more 4. The working section structure of a belt sander according to claim 1, wherein the working section structure is a belt sander.

5. The flanges are provided on both sides of the belt contact portion in a width direction, The flange radius b is the distance between the center axis of the drive wheel and the tip of one of the flanges. Ｄ From the above, the belt contact radius a, which is the distance between the central axis and the belt contact portion, Ｄ The value obtained by subtracting 1 is the flange interval c, which is the distance between the two flanges. Ｄ The value divided by ((b Ｄ -a Ｄ ) / c Ｄ ) is less than or equal to 1.00 5. The working section structure of a belt sander according to claim 1.

6. The height of the flange is 3 mm or more.

6. The working section structure of a belt sander according to claim 1.

7. The belt speed, which is the speed of the sanding belt, can be set to 3.4 m / s or less.

7. The working part structure of a belt sander according to claim 1.

8. The flange is made of synthetic resin.

8. The working section structure of a belt sander according to claim 1.

9. The drive wheel has an outer ring portion that is either integral with or separate from the flange portion.

9. The working section structure of a belt sander according to claim 1.

10. The flange is made of polyamide.

10. The working part structure of a belt sander according to claim 9.

11. The outer ring portion further includes a rubber belt guide portion, The belt guide portion is disposed axially inside the flange portion and has the belt contact portion.

11. The working part structure of a belt sander according to claim 9 or 10.

12. A part or the whole of the flange portion is separate from the outer ring portion.

12. The working section structure of a belt sander according to claim 9, wherein the working section structure is a belt sander.

13. The belt contact portion includes tip surfaces of a plurality of ribs.

13. The working section structure of a belt sander according to claim 1.

14. A structure of a working part for performing work on a workpiece in a belt sander, Drive wheel onto which the sanding belt is attached It is equipped with The drive wheel has a belt contact portion that is a portion that comes into contact with the sanding belt, and a flange portion made of synthetic resin that is adjacent to the belt contact portion.

1. A working part structure of a belt sander.

15. The drive wheel has an outer ring portion that is either integral with or separate from the flange portion.

15. The working part structure of a belt sander according to claim 14.

16. The flange is made of polyamide.

16. The working part structure of a belt sander according to claim 15.

17. The outer ring portion further includes a rubber belt guide portion, The belt guide portion is disposed axially inside the flange portion and has the belt contact portion.

17. The working part structure of a belt sander according to claim 15 or 16.

18. A part or the whole of the flange portion is separate from the outer ring portion.

18. The working part structure of a belt sander according to claim 15, wherein the working part structure is a belt sander.

19. A belt sander having the working part structure according to any one of claims 1 to 18. A belt sander attachment characterized by the above.

20. A belt sander having the working part structure according to any one of claims 1 to 18. A belt sander characterized by:

21. A brushless motor is provided as a drive source for the drive wheel.

21. The belt sander of claim 20.

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