JP2014128846A - Belt type grinding tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt type grinding tool in which sufficient tension can be applied while a grinding belt is rotating even though a coil having relatively weak elastic force is used.SOLUTION: In a belt type grinding tool in which a grinding belt 94 is wound on a drive pulley 50 rotated and driven by a motor and an idle pulley 60 mounted as rotatable, a tension-adjusting pulley 70 engaging with an inner circular surface 98 of the grinding belt 94 is mounted as rotatable to a tension-adjusting pulley holding member 80 which can move pivotally around a pivot line 32, and is for applying tension by being pressed to the inner circular surface 98 of the grinding belt 94 by an energizing member 90. The pivot line 32 of the tension-adjusting pulley holding member 80 is at the inside position surrounded by the grinding belt 94, and the energizing member 90 energizes the tension-adjusting pulley holding member 80 around the pivot line 32 in the same direction as the direction of the drive rotation of the drive pulley 50.

Description

  The present invention relates to a grinding tool, and more particularly, to a belt-type grinding tool that grinds an object by rotating and driving an endless grinding belt into contact with the object.

  The belt-type grinding tool includes a drive pulley that is rotationally driven by a motor, a rotatable idle pulley, a grinding belt that is hung on the drive pulley and the idle pulley, and tension adjustment for applying a constant tension to the grinding belt. And a grinding tool that grinds the object by bringing a grinding belt, which is rotationally driven as the drive pulley rotates, into contact with the object.

  In a general belt-type grinding tool, an elongated cylindrical member that extends forward at right angles to the rotational axis of the drive pulley that extends from the tool body that rotatably supports the drive pulley, and slides coaxially with the cylindrical member An idle pulley having a tension bar that is rotatably arranged and holds the idle pulley rotatably at the front end thereof, and a compression coil spring that is arranged in the tubular member and urges the tension bar to push forward. Is engaged with the inner peripheral surface of the grinding belt and presses the grinding belt outward by the urging force of the compression coil spring to apply a constant tension to the grinding belt (Patent Document 1). In such a belt-type grinding tool, the compression coil spring is required to have a sufficiently strong elastic force to apply the tension required for the grinding belt during the grinding operation. Also, when replacing the grinding belt, it is difficult to perform the belt replacement work while keeping the tension bar biased with strong elastic force in the pressed state, so that the tension bar is kept pressed. It is also necessary to further include a locking mechanism.

  In another belt-type grinding tool, an endless grinding belt is hung between a drive pulley attached to one end of an elongated support member and an idle pulley attached to the other end, and the drive pulley and the idle pulley are connected to each other. A tension belt that is rotatably attached to the tip of a pivot bracket that is pivotally attached to a support member at a position in between, is engaged with the inner peripheral surface of the grinding belt, and the grinding belt is engaged with the tension pulley The pivot bracket is spring-biased around the pivot shaft so as to press the inner surface in the outer direction opposite to the traveling direction of the traveling portion, so that tension is applied to the grinding belt. (Patent Document 2). In such a belt-type grinding tool, when the grinding belt is driven to rotate, the tension pulley that applies tension to the grinding belt receives the force in the traveling direction by the frictional force received from the grinding belt. A pivotal force against the urging force of the spring is applied to. At this time, if the tension pulley is moved by this pivotal force, the tension of the grinding belt is lowered. Therefore, even in this kind of grinding tool, a spring biasing force sufficient to counter the pivotal force from the grinding belt is required.

  Thus, the conventional belt-type grinding tool must use a biasing member having a strong biasing force. For this reason, for example, when replacing the grinding belt, the pulley that presses the grinding belt is spring-loaded. A large force is required to move against the biasing force and release the tension on the grinding belt. In addition, a lock mechanism is required to maintain the released tension, which causes the tool to become complicated and large, and a large tension is always applied to the grinding belt even when it is not in use. Since it continues, there is a possibility that the grinding belt may be extended.

Patent 4847363 Japanese Utility Model Publication No.59-136251

  An object of the present invention is to provide a belt-type grinding tool that can solve the problems of the conventional belt-type grinding apparatus described above.

That is, the present invention
A tool body;
A drive pulley provided in the tool body and driven to rotate by a motor;
An idle pulley that is rotatably attached to the tool body and is wound around a grinding belt together with the drive pulley;
A tension adjusting pulley holding member pivotally attached to the tool body;
A tension adjustment pulley rotatably attached to the tension adjustment pulley holding member and engaged with an inner peripheral surface of the grinding belt;
A biasing member that biases the tension adjusting pulley holding member around the pivot shaft of the tension adjusting pulley holding member and presses the tension adjusting pulley against the inner peripheral surface of the grinding belt to apply tension to the grinding belt. When,
With
The pivot shaft of the tension adjusting pulley holding member is in an inner position surrounded by the grinding belt, and the biasing member pivots the tension adjusting pulley holding member in the same direction as the drive rotation direction of the drive pulley. A belt grinding tool is provided that is adapted to be biased about an axis.

  In this belt-type grinding tool, the tension adjusting pulley holding member pivots by the force received from the grinding belt rotating via the tension adjusting pulley when the grinding belt is wound around each pulley and the drive pulley is driven to rotate. However, since the direction is the same as the direction of pivoting by the urging force of the urging member, this force acts to further increase the pressing force of the tension adjusting pulley against the grinding belt. Therefore, the pressing force applied to the grinding belt by the tension adjustment pulley during rotation of the grinding belt is the sum of the biasing force of the biasing member and the force from the rotating grinding belt. Can be made small. That is, it is possible to use a biasing member having a relatively weak elastic force. Thereby, when exchanging the grinding belt, the tension adjusting pulley holding member can be tilted with a small force against the urging force of the urging member, so that the exchanging operation of the grinding belt is facilitated. Further, since the force required to hold the tension adjusting pulley holding member in the released state is small, it is not necessary to separately provide a lock mechanism, the structure is simplified, and the tool can be easily downsized. In addition, the number of parts is reduced, and it is possible to reduce production costs and occurrence of failures. Furthermore, when the grinding belt is not rotationally driven, the tension applied to the grinding belt by the tension adjusting pulley is relatively small, so the load on the grinding belt when not driven can be reduced and the life of the grinding belt can be extended. It becomes possible to do.

  Specifically, the position where the tension adjusting pulley presses the inner peripheral surface of the grinding belt is moved from the idle pulley to the drive pulley when the grinding belt is rotationally driven by the drive pulley. It can be the position between.

  Since the tension adjusting pulley is engaged with the grinding belt that is strongly pulled by the drive pulley, the tension adjusting pulley can receive the force from the rotating grinding belt more reliably, and a more stable tension is applied to the grinding belt. Can be generated.

  More specifically, the tool body has a housing part that holds the drive pulley, and a pulley support bar that extends from the housing part to the idle pulley and holds the idle pulley. can do.

  More specifically, the tension adjusting pulley holding member can be pivotally attached to the pulley support bar.

  Preferably, the width of the idle pulley and the pulley support bar can be made smaller than the width of the grinding belt.

  Even when the grinding belt is worn and its width is reduced, the idle pulley and the pulley support bar do not immediately interfere with the object to be ground, so that the grinding belt can be used for a longer time.

  More preferably, a grinding belt that is wound around the drive pulley, the idle pulley, and the tension adjusting pulley and is rotated in accordance with the rotational drive of the drive pulley can be further provided.

  More preferably, the circumferential length of the grinding belt can be between 200 mm and 240 mm.

  In addition, the outer peripheral surfaces of the drive pulley and the idle pulley have a middle-high shape in which the diameter of the center portion is larger than the diameter of the side edge portions on both sides thereof, and the drive pulley and the idle pulley are the drive pulley. The central portion of the idle pulley and the central portion of the idle pulley can be arranged in a straight line.

  In this way, when the drive pulley is driven to rotate with the grinding belt attached, the position of the grinding belt in the width direction can be automatically aligned with respect to each pulley. It becomes.

  Preferably, a motor that is provided in the tool body and rotationally drives the drive pulley may be further provided.

  Hereinafter, embodiments of a belt-type grinding tool according to the present invention will be described with reference to the accompanying drawings.

It is a side view of the belt type grinding tool concerning the embodiment of the present invention. FIG. 2 is an upper cross-sectional view of the belt-type grinding tool of FIG. 1. It is a side view of the state which removed the cover part of the belt type grinding tool of FIG. FIG. 4 is a front cross-sectional view of the belt-type grinding tool of FIG. 1 on line IV-IV. FIG. 2 is a side view of a state in which the grinding belt of the belt-type grinding tool of FIG. 1 is removed and no external force is applied to the urging member. FIG. 6 is a side view showing a state in which an external force is applied to the tension adjusting pulley holding member of the belt-type grinding tool of FIG. 5 and tilted forward. FIG. 7 is a side view of a state in which a grinding belt is attached to the belt-type grinding tool of FIG. 6.

  As shown in FIGS. 1, 2, and 3, a belt-type grinding tool 10 according to an embodiment of the present invention has an overall cylindrical shape that houses an air motor 12 and a drive pulley 50 that is rotationally driven by the air motor 12. The housing 20, the pulley support bar 30 extending forward from the housing 20 in the direction perpendicular to the rotation axis 52 of the drive pulley 50, and the drive pulley 50 provided on the side of the housing 20 It has a tool body 16 composed of a cover portion 40 attached to the housing portion 20 so as to cover the side opening portion 22 that can be accessed in the direction of the rotation axis 52, and an operator holds it with one hand for grinding. The shape is suitable for work. An idle pulley 60 is rotatably attached to the front end portion 31 of the pulley support bar 30 via a bearing 62, and an endless grinding belt 94 is wound around the idle pulley 60 and the drive pulley 50. ing.

  The housing 20 also has a front opening 25 through which the upper traveling portion 95 and the lower traveling portion 96 of the grinding belt 94 that opens forward from the internal space 17 that houses the drive pulley 50 and extends in the front-rear direction are passed. Is provided. A gap is formed between the outer peripheral edge portion 42 of the cover portion 40 and the side surface opening edge portion 23 of the side surface opening portion 22 of the housing portion 20, and a belt insertion opening 46 is formed on the side surface of the tool body 16. ing. The belt insertion opening 46 passes through the upper position of the drive pulley 50 from the position communicating with the upper front opening 26 that opens toward the front of the tool body 16 above the pulley support bar 30 and passes through the upper position of the drive pulley 50. The rear circulates to the lower position of the drive pulley 50 and continues to a position communicating with the lower front opening 27 that opens below the pulley support bar 30 toward the front of the tool body 16. By providing such a belt insertion opening 46, a part of the endless grinding belt 94 is inserted into the internal space 17 of the tool main body 16 through the belt insertion opening 46 and hung on the drive pulley 50. The remaining portion can be extended from the front opening 25 of the tool body 16 and hung on the idle pulley 60. That is, the grinding belt 94 can be attached / detached (exchanged) without removing the cover 40. Therefore, the belt replacement work can be performed very simply. In the present embodiment, one front opening 25 that opens toward the front of the tool body 16 is formed between the housing 20 and the cover 40, and as shown in FIG. The lower front opening 27 is formed by dividing the front opening 25 into upper and lower portions by a pulley support bar 30 attached between the housing 20 and the cover 40. The pulley support bar 30 does not need to divide the front opening 25 into upper and lower portions, and can be provided so as to be inserted through the front opening 25 in the front-rear direction.

  As can be seen from FIG. 2, the pulley support bar 30 and the cover portion 40 are configured such that one end of the front pin 36 fixed to the pulley support bar 30 engages with the front pin receiving hole 28 of the housing portion 20 and the other end is the cover portion. 40, and one end of the rear pin 38 fixed to the pulley support bar 30 engages with the rear pin receiving hole 29 of the housing portion 20 and the other end, as can be seen from FIG. With the screw 18 engaged with the rear pin receiving hole 49 of the cover portion 40, the screw 18 is screwed from the cover portion 40 through the pulley support bar 30 to the screw hole 21 of the housing portion 20 and fixed. Assembling can be performed with only one screw 18, so that it is easy to attach / remove the cover portion 40.

  As can be seen from FIG. 3 showing the state where the cover portion 40 is removed, the tension adjusting pulley holding member 80 is located around the pivot line 32 extending in the left-right direction with respect to the pulley support bar 30 at the intermediate position in the front-rear direction of the pulley support bar 30. The tension adjusting pulley 70 is rotatably attached to the front end portion 82 of the tension adjusting pulley holding member 80. A tension coil spring 90 as an urging member is provided between the tension adjustment pulley holding member 80 and the tool body 16, and the tension coil spring 90 has hooks at both ends of the tension coil pulley 90, respectively. Are engaged with and stretched by a pin 84 provided at an intermediate position of this pin and a spring fixing screw 86 provided at the rear end portion 33 of the pulley support bar 30. The tension adjusting pulley holding member 80 is urged around the pivot line 32 counterclockwise as viewed in the figure by the tension coil spring 90, and is engaged with the inner peripheral surface 98 of the grinding belt 94. The tension is applied to the grinding belt 94.

  The air motor 12 incorporated in the housing unit 20 is communicated with a fluid supply source (not shown) through the valve 2 and is supplied with compressed air from the fluid supply source, so that it can be seen in FIG. The drive pulley 50 is driven to rotate clockwise, thereby driving the drive pulley 50 counterclockwise. Accordingly, the lower traveling portion 96 of the grinding belt 94 with which the tension adjusting pulley 70 is engaged is driven in the same direction as the pivoting direction of the tension adjusting pulley holding member 80. A lower traveling portion 96 of the grinding belt 94 pressed by the tension adjusting pulley 70 is a portion to which a pulling force is applied by the drive pulley 50. For this reason, when the grinding belt 94 is rotationally driven by the drive pulley 50, the grinding belt 94 travels from the tension adjustment pulley 70 toward the drive pulley 50 due to frictional force with the grinding belt 94. A force in the direction (in the direction of arrow A) is applied, and therefore, in addition to the biasing force by the tension coil spring 90, the force received from the lower running portion 96 of the grinding belt 94 is also applied to the tension adjusting pulley holding member 80. As a result, the counterclockwise biasing force to the tension adjusting pulley holding member 80 is increased, and as a result, a larger tension is applied to the grinding belt 94. Therefore, in the belt-type grinding tool 10 according to the present invention, even if the urging force (elastic force) of the tension coil spring 90 is smaller than that of the belt-type grinding tool of the type of Patent Document 2 described above, the belt Necessary tension can be applied to the grinding belt 94 when the grinding tool 10 is in operation.

  Thus, in the belt-type grinding tool 10 of the present invention, the elastic force of the tension coil spring 90 for adjusting the tension of the grinding belt 94 can be made relatively small. In the work, the tension adjusting pulley 70 can be easily moved by the operator's hand against the urging force of the urging member, and the labor for maintaining the state can also be reduced. The replacement work of the belt 94 is facilitated. Furthermore, since a strong coil spring is not required, the rigidity of the tool body 16 that supports the coil spring can be reduced, and therefore the weight of the tool 10 can be reduced.

  As shown in FIG. 1, the cover portion 40 is preferably shaped so as to substantially cover the tension adjustment pulley 70 with the grinding belt 94 attached thereto. Further, the tension adjusting pulley holding member 80 and the tension coil spring 90 may be covered. By doing so, it is possible to reduce the risk that the operator may accidentally touch the drive member or the like to cause injury.

  The outer peripheral surfaces 55 and 65 of the drive pulley 50 and the idle pulley 60 that frictionally engage with the grinding belt 94 have a medium-high shape in which the diameters of the center portions 56 and 66 are larger than the diameters of the side edge portions 57 and 67, respectively. The central portions 56 and 66 are arranged so as to be in a straight line. As a result, the grinding belt 94 is automatically aligned. A guide 58 having a diameter larger than that of the outer peripheral surface 55 is formed on the side edge portion 57 of the outer peripheral surface 55 of the drive pulley 50 at a distance larger than the width of the grinding belt 94. The drive pulley 50 is prevented from coming off.

  In the present embodiment, a grinding belt 94 having a width of 10 mm and a circumferential length of 200 to 240 mm, preferably a circumferential length of 220 mm is used. In the conventional standard belt-type grinding tool represented by Patent Document 1 described above, the circumferential length of the grinding belt is 330 mm. Therefore, in this embodiment, the grinding belt is greatly shortened. In this conventional belt-type grinding tool, a tension bar is set in a nested manner with respect to a tubular member so as to expand and contract, and a necessary tension is applied to the grinding belt therebetween (described above in the present invention). As a result, the length of the grinding tool in the longitudinal axis direction is increased, resulting in the fact that the grinding belt in the conventional tool has It is a major factor that gets longer. Further, in the above conventional grinding tool, since the coil spring has a strong elastic force, a lock mechanism for keeping the tension bar pushed in for exchanging the grinding belt is also necessary. Thus, since the tension coil spring 90 can have a small elastic force, the grinding belt 94 can be easily replaced without providing such a locking mechanism. The tool 10 can be downsized. As described above, the belt-type grinding tool 10 according to the present invention has a smaller number of parts, a smaller size and a simpler structure than the conventional tool of Patent Document 1, and a product with fewer failures can be obtained. It becomes possible to produce at a cost. Since the length of the grinding belt 94 is also short, the twist of the belt and the deviation in the width direction can be reduced, and the removal of the grinding belt during operation can be reduced as compared with the conventional one. Further, in the belt type grinding tool 10 according to the present invention, as described above, the elastic force of the coil spring for applying tension to the grinding belt as compared with that of the conventional belt type grinding tool of the type of Patent Document 2. Therefore, the same effect as that of the conventional tool of Patent Document 1 described above, such as the downsizing of the tool and the simplification of the structure, can be achieved compared to the conventional grinding tool. An effect can be produced.

  Since the conventional belt-type grinding tool does not have the self-aligning function as described above, the width of the grinding belt 94 is the same as or smaller than the width of the idle pulley 60 (and the pulley support bar 30). It was necessary to make it difficult to come off the pulley. On the other hand, in the belt type grinding tool 10 according to the present embodiment, as described above, the grinding pulley 94 is automatically aligned with the drive pulley 50 and the idle pulley 60 at the middle and the idle pulley 60. In addition, the width of the pulley support bar 30 that supports it can be made smaller than the width of the grinding belt 94 so that both side portions of the grinding belt 94 extend from the pulley and the pulley support bar 30 to both sides. This is because the amount of extension of the grinding belt 94 to both sides can be constant for automatic alignment, and the belt can be driven in a stable state. Specifically, the width of the pulley support bar 30 is 6 mm with respect to the width of the grinding belt 94 of 10 mm. This is because, for example, a corner such as a corner portion inside a box is ground, the grinding belt extending to both sides without bringing the idle pulley 60 and the pulley support bar 30 too close to the wall portion defining the corner portion. This is because the corner portion 94 can be ground. Further, the grinding operation can be continued even when the grinding belt 94 is worn and the width is reduced to some extent. In this embodiment, the width of the grinding belt 94 is 10 mm, but other widths such as 15 mm and 20 mm may be used, and the widths of the idle pulley 60 and the pulley support bar 30 can be changed accordingly. .

  Next, a method for attaching the grinding belt 94 will be described. First, the grinding belt 94 is inserted into the internal space 17 from the belt insertion opening 46 (FIG. 1) formed between the cover portion 40 and the housing portion 20 and is hung on the drive pulley 50. An inclined surface 24 that is inclined toward the drive pulley 50 is formed on the side surface opening edge 23 of the housing portion 20 that forms the outer peripheral surface of the belt insertion opening 46 so that the grinding belt 94 can be easily inserted. It is like that. Further, an inclined surface 44 in the same direction is formed on the outer peripheral edge 42 of the cover 40 that forms the inner inner peripheral surface of the belt insertion opening 46 so as to be directed outward from near the outer periphery of the drive pulley 50, The grinding belt 94 can be easily taken out when the grinding belt 94 described later is removed. Next, as shown in FIG. 5, the tension adjustment pulley holding member 80 in a state in which the tension coil spring 90 is in a natural length and no urging force is applied is pushed in the direction of arrow B and tilted toward the idle pulley 60. A state as shown in FIG. A receiving groove 34 is formed in the pulley support bar 30 so as to receive a part of the tip 82 of the tilted tension adjusting pulley holding member 80. The receiving groove 34 allows the tension adjusting pulley holding member 80 to be greatly tilted, so that the space between the receiving belt 34 and the grinding belt 94 can be opened sufficiently for exchanging the grinding belt 94. Next, the portion of the grinding belt 94 extending from the front opening 25 in the state of FIG. 6 is also hung on the outer peripheral surfaces 65 and 75 of the idle pulley 60 and the tension adjusting pulley 70, and the tension adjusting pulley holding member 80 is pushed. Release the external force. Then, as shown in FIG. 7, the tension adjusting pulley holding member 80 is urged in the direction of arrow C by the tension coil spring 90, and the tension adjusting pulley 70 engages with the inner peripheral surface 98 of the grinding belt 94. It will be in the state which pressed 94 toward outward. Tension is applied to the grinding belt 94 by the pressing force from the tension adjusting pulley 70 so that the grinding belt 94 is in a tensioned state, and the mounting operation of the grinding belt 94 is completed.

  When removing the grinding belt 94, first, the tension adjusting pulley holding member 80 is tilted toward the idle pulley 60, and the pressing force of the tension adjusting pulley holding member 80 against the grinding belt 94 is released. As a result, the grinding belt 94 is slackened and a gap is formed between the grinding belt 94 and the idle pulley 60, so that the grinding belt 94 can be removed from the idle pulley 60. When the grinding belt 94 is removed from the idle pulley 60, the grinding belt 94 is also removed from the drive pulley 50 in the internal space 17, and the grinding belt 94 is taken out through the belt insertion opening 46. This completes the removal work of the grinding belt 94.

  As described above, the exchanging operation of the grinding belt 94 in the belt-type grinding tool 10 according to the present embodiment is very simple because there is no work for disassembling the belt-type grinding tool 10, for example, the work for removing the cover portion 40 or the like. It is also possible to complete the replacement operation of the grinding belt 94 very quickly. The belt-type grinding tool 10 according to the present invention can achieve a significant reduction in size as described above. However, when the tool is downsized and the grinding belt 94 is shortened, wear of the grinding belt 94 is accelerated. Therefore, the replacement frequency of the grinding belt 94 is increased. However, since the belt-type grinding tool 10 of the present embodiment can complete the replacement of the grinding belt 94 in a very simple and short time, frequent replacement work of the grinding belt 94 is not a big problem.

  In this embodiment, the air motor 12 is used as a drive source for driving the drive pulley 50, but other drive sources such as an electric motor may be used. The tension coil spring 90 is used as a biasing member that biases the tension adjusting pulley holding member 80. However, the tension adjusting pulley holding member 80 is moved in the same direction as the rotation direction of the drive pulley 50 by a compression coil spring, a torsion spring, or the like. You may comprise so that it may urge.

2 Valve 10 Belt type grinding tool 12 Air motor 16 Tool body 17 Internal space 18 Screw 20 Housing portion 21 Screw hole 22 Side opening 23 Side opening edge 24 Inclined surface 25 Front opening 26 Upper front opening 27 Lower front opening 28 Front pin receiving hole 29 Rear pin receiving hole 30 Pulley support bar 31 Front end portion 32 Axis line 33 Rear end portion 34 Receiving groove 36 Front pin 38 Rear pin 40 Cover portion 42 Outer peripheral edge portion 44 Inclined surface 46 Belt insertion opening 48 Front portion Pin receiving hole 49 Rear pin receiving hole 50 Drive pulley 52 Rotating axis 54 Outer side surface 55 Outer surface 56 Center portion 57 Side edge 58 Guide 60 Idle pulley 62 Bearing 65 Outer surface 66 Center portion 67 Side edge 70 Tension adjusting pulley 75 Outer periphery Surface 80 Tension adjusting pulley holding member 82 Tip 84 Pin 86 Spring Fixing screw 90 Pulling coil spring 94 Grinding belt 95 Upper traveling portion 96 Lower traveling portion 98 Inner circumferential surface

Claims (9)

A tool body;
A drive pulley provided in the tool body and driven to rotate by a motor;
An idle pulley that is rotatably attached to the tool body and is wound around a grinding belt together with the drive pulley;
A tension adjusting pulley holding member pivotally attached to the tool body;
A tension adjustment pulley rotatably attached to the tension adjustment pulley holding member and engaged with an inner peripheral surface of the grinding belt;
A biasing member that biases the tension adjusting pulley holding member around the pivot shaft of the tension adjusting pulley holding member and presses the tension adjusting pulley against the inner peripheral surface of the grinding belt to apply tension to the grinding belt. When,
With
The pivot shaft of the tension adjusting pulley holding member is in an inner position surrounded by the grinding belt, and the biasing member pivots the tension adjusting pulley holding member in the same direction as the drive rotation direction of the drive pulley. A belt-type grinding tool designed to bias around an axis.   The position where the tension adjusting pulley presses the inner peripheral surface of the grinding belt is a position between the idle belt and the drive pulley when the grinding belt is driven to rotate by the drive pulley. The belt-type grinding tool according to claim 1, wherein   The said tool main body has the housing | casing part which hold | maintains the said drive pulley, and the pulley support bar which extends from this housing | casing part to the said idle pulley and hold | maintains this idle pulley. Belt type grinding tool.   The belt-type grinding tool according to claim 3, wherein the tension adjusting pulley holding member is pivotally attached to the pulley support bar.   The belt-type grinding tool according to any one of claims 2 to 4, wherein a width of the idle pulley and the pulley support bar is smaller than a width of the grinding belt.   6. The grinding belt according to any one of claims 1 to 5, further comprising a grinding belt that is wound around the drive pulley, the idle pulley, and the tension adjusting pulley and is rotated in accordance with the rotational drive of the drive pulley. Belt type grinding tool.   The belt-type grinding tool according to claim 6, wherein the circumferential length of the grinding belt is between 200 mm and 240 mm.   The outer peripheral surfaces of the drive pulley and the idle pulley have a middle-high shape in which the diameter of the center portion is larger than the diameters of the side edge portions on both sides thereof, and the drive pulley and the idle pulley are the center of the drive pulley. The belt-type grinding tool according to any one of claims 1 to 7, wherein the belt grinding tool is disposed so that the portion and the center portion of the idle pulley are in a straight line.   The belt type grinding tool according to any one of claims 1 to 8, further comprising a motor that is provided in the tool body and that rotationally drives the drive pulley.

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