CN108883512B

CN108883512B - Belt type grinding tool

Info

Publication number: CN108883512B
Application number: CN201780016083.5A
Authority: CN
Inventors: 铃木保全
Original assignee: Nitto Kohki Co Ltd
Current assignee: Nitto Kohki Co Ltd
Priority date: 2016-03-11
Filing date: 2017-03-10
Publication date: 2020-09-11
Anticipated expiration: 2037-03-10
Also published as: GB2562436B; WO2017155107A1; CN108883512A; TWI619576B; JP6568997B2; GB201813241D0; KR20180107219A; KR102083156B1; DE112017001265T5; JPWO2017155107A1; GB2562436A; TW201738033A; DE112017001265B4

Abstract

The invention provides a belt type grinding tool, wherein a spring supporting member is not pivoted to a direction of releasing the compression of a spring due to the acting force received from the spring. The belt type grinding tool is provided with a spring support member (38) which can pivot between a tension applying position and a tension releasing position, wherein a pressing support surface (46) presses an engagement part (44) of a spring seat (30) at the tension applying position to compress and support the spring (32) between the pressing support surface (46) and a pulley support rod (16) so as to form a state of applying tension to the annular grinding belt (20), and the compression amount of the spring (32) is reduced at the tension releasing position so as to reduce the tension. The pressing support surface (46) and the engagement portion (44) are shaped such that, when the spring support member (38) is located at the tension application position, the line of action of force received by the pressing support surface (46) of the spring support member (38) from the engagement portion (44) of the spring seat (30) passes, with respect to the pivot axis (R), on the side where a moment is generated that pivots the spring support member (38) in a direction away from the tension release position.

Description

Belt type grinding tool

Technical Field

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

Background

The belt type grinding tool is provided with: the grinding machine is configured to grind an object by bringing an endless grinding belt, which is driven to rotate in conjunction with the rotation of the drive pulley, into contact with the object. A pulley support lever that supports the idle pulley is held by a tool body provided with a drive pulley so as to be slidable in the front-rear direction, and is biased forward by a spring provided in the tool body. The endless grinding belt mounted on the drive pulley and the idler pulley is applied with a moderate tension by the urging force of the spring.

The endless grinding belt is a consumable product and needs to be replaced at a stage where grinding work is performed and there is a certain degree of wear. In the replacement work, normally, the pulley support lever is pushed in backward against the biasing force of the spring, the pulley support lever is maintained at the backward position by the lock mechanism, and the cover covering the drive pulley is removed to perform the removal and attachment work of the endless grinding belt (patent document 1).

However, in the above-described replacement work of the endless grinding belt, in order to apply tension to the endless grinding belt, the pulley support rod must be pushed in to further compress the spring that has been compressed and generates the urging force, and therefore a large force is required for this operation. Accordingly, a belt type grinding tool which does not require such a large force has been developed (patent document 2). In this belt type grinding tool, the spring support member that applies tension to the endless grinding belt as the support spring is formed so as to be pivotable so as to retreat the support surface of the support spring, and the amount of compression of the spring can be reduced by retreating the support surface, so that the idler pulley is easily retreated together with the pulley support rod. This allows the pulley support bar to be pushed in with a smaller force than the grinding tool disclosed in patent document 1, and allows the endless grinding belt to be easily replaced.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open No. 2004-58216

Patent document 2: japanese patent laid-open No. 2014-166668

Disclosure of Invention

Problems to be solved by the invention

However, in the belt type grinding tool as shown in the cited document 2, the spring support member supporting the spring receives a biasing force from the spring in a state where the spring is compressed, and receives a rotational moment pivoting in a direction of retracting the pressing support surface. Therefore, in order to maintain the state in which the spring is compressed, a mechanism such as a hook for fixing the spring support member to the tool body needs to be separately provided.

In view of the above-described problems of the prior art, it is an object of the present invention to provide a belt type grinding tool in which a spring support member is not pivoted in a direction to release compression of a spring by an urging force received from the spring.

Means for solving the problems

That is, the present invention provides a belt-type grinding tool including: a tool body; a drive pulley provided in the tool body and driven to rotate by a motor; an idle pulley set at a position separated forward from the drive pulley, and having an endless grinding belt stretched between the idle pulley and the drive pulley; a pulley support rod having a front end portion rotatably supporting the idle pulley, the pulley support rod extending rearward from the front end portion and slidably supported by the tool body; a spring that urges the pulley support lever forward with respect to the tool body, and that urges the idler pulley supported by the pulley support lever forward to press the endless grinding belt, thereby applying tension to the endless grinding belt; a spring seat engaged with a rear end portion of the spring; and a spring support member that is attached to the tool body so as to be pivotable about a pivot axis and that has a pressing support surface that contacts an engagement portion of the spring seat, the spring support member being pivotable between a tension application position at which the pressing support surface presses the engagement portion to compress and support the spring between the pressing support surface and the pulley support lever, thereby forming a state in which the idler pulley applies tension to the endless grinding belt, and a tension release position at which the pressing support surface is pivoted in a first pivot direction so as to be displaced rearward from the tension application position, an amount of compression of the spring being reduced, thereby reducing the tension applied to the endless grinding belt, the pressing support surface and the engagement portion being shaped such that, when the spring support member is located at the tension applying position, a line of action of a force received by the pressing support surface of the spring support member from the engagement portion of the spring seat passes through or on the pivot axis on a side where a moment that pivots the spring support member in a second pivot direction opposite to the first pivot direction is generated with respect to the pivot axis.

In this belt type grinding tool, when the spring bearing member is located at the tension applying position, the line of action of the force received by the spring bearing member from the spring seat passes through or on the pivot axis on the side where the moment that pivots it in the second pivot direction (i.e., in the direction toward the tension applying position) is generated, while no moment is generated in the first pivot direction (i.e., in the direction toward the tension releasing position). Accordingly, the spring support member can be prevented from pivoting from the tension applying position toward the tension releasing position by the biasing force of the spring, and the state in which the spring is compressed can be maintained. The "tension release position" herein includes not only a state in which the compression of the spring is completely eliminated and the tension is not applied to the endless grinding belt at all, but also a state in which the compression of the spring is reduced and the tension is applied to the endless grinding belt weakly.

Preferably, the pivot axis of the spring bearing member is located at a position shifted from a long-side axis of the pulley support lever, and the pressing support surface and the engaging portion are shaped such that a normal line at a contact point on the pressing support surface with which the engaging portion of the spring seat contacts passes on a side opposite to the long-side axis with respect to the pivot axis when the spring bearing member is located at the tension applying position.

More preferably, the pressing support surface and the engaging portion are shaped so that, when the spring support member is located at the tension applying position, the pressing support surface and the engaging portion contact at a contact point other than the contact point, and a normal line to the pressing support surface at the contact point passes on the same side as the long-side axis with respect to the pivot axis.

With such a configuration, the spring support member can be held at the tension applying position only by the force received from the spring.

Preferably, the pressing support surface has an inclined plane inclined with respect to the longitudinal axis when the spring support member is located at the tension application position, and the engagement portion of the spring seat has an inclined portion having an inclination angle substantially equal to the inclined plane when the spring support member is located at the tension application position.

According to such a structure, the portions having the same inclination angle contact each other, and therefore the spring bearing member can be held in a more stable state at the tension applying position.

More preferably, the engaging portion is a conical surface centered on the long axis, and the inclined portion constitutes a part of the conical surface.

According to such a configuration, the engaging portion of the spring seat can always be appropriately brought into contact with the pressing support surface of the spring support member regardless of the rotational position of the spring seat about the longitudinal axis.

Preferably, the tool body has: a spring support member housing space that houses at least a part of the spring support member; and a slide accommodating hole that communicates with the spring support member accommodating space, holds the pulley support rod and the spring seat slidably in a direction of a longitudinal axis of the pulley support rod, and accommodates the spring set between the spring support member and the spring seat, wherein when the spring support member pivots between the tension applying position and the tension releasing position, at least a part of the spring seat slides relative to the slide accommodating hole in a state of being always accommodated in the slide accommodating hole.

According to this configuration, since the spring receiving member accommodating space and the slide accommodating hole are blocked by the spring seat, it is possible to prevent foreign matter such as dust from entering the slide accommodating hole from the spring receiving member accommodating space side.

Preferably, the belt type grinding tool further includes a cover attached to the spring support member,

the tool body further has: an upper front surface opening through which an upper traveling portion of the endless grinding belt stretched between the drive pulley and the idler pulley passes; a lower front opening through which a lower traveling portion of the endless grinding belt passes; and a side opening portion that is connected to the upper front opening portion and the lower front opening portion and that is opened so as to expose a side surface portion of the drive pulley, wherein the cover covers the side opening portion when the spring support member is located at the tension applying position, and the cover exposes the side opening portion to be accessible to the drive pulley when the spring support member is located at the tension releasing position, so that the endless grinding belt can be attached to or detached from the drive pulley through the side opening portion.

The spring support member is integrated with the cover, and the operation of releasing the tension of the endless grinding belt and the operation of opening the cover to make the drive pulley accessible are completed in one operation, so that the replacement operation of the endless grinding belt can be performed more simply. Further, the spring support member must be set to the tension applying position in order to be able to drive the endless grinding belt to rotate, but since the drive pulley is covered with the cover at this time, the endless grinding belt is not driven to rotate in a state where the drive pulley is exposed, and the risk that the operator's hand or the like is accidentally caught between the driven and rotated endless grinding belt and the drive pulley is reduced.

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

Drawings

Fig. 1 is a top partial sectional view showing a main part of a belt type grinding tool according to an embodiment of the present invention in section.

Fig. 2 is a partially enlarged view of fig. 1, and is a view showing a state in which a spring bearing member of the belt type grinding tool is located at a tension applying position.

Fig. 3 is a partially enlarged view of fig. 1, and is a view showing a state in which the spring bearing member is located at an intermediate position.

Fig. 4 is a partially enlarged view of fig. 1, and is a view showing a state in which the spring bearing member is located at the tension releasing position.

Fig. 5 is a side view of the belt type grinding tool of fig. 1, which is a view showing a state in which the spring support member is located at the tension applying position and the cover is closed.

Fig. 6 is a side view of the belt type grinding tool of fig. 1, showing a state in which the spring bearing member is located at the tension releasing position and the cover is opened.

Fig. 7 is a diagram showing the force received by the spring support member.

Fig. 8 is a diagram showing forces received by the spring support member of the belt type grinding tool of the second embodiment.

Detailed Description

As shown in fig. 1, a belt-type grinding tool 1 according to an embodiment of the present invention includes a tool body 10 that houses an air motor 12 and a drive pulley 14, a pulley support rod 16 that extends forward (upward in the drawing) from the tool body 10, and an idle pulley 18 that is rotatably attached to a front end portion 16a of the pulley support rod 16 via a bearing, and an endless grinding belt 20 is stretched between the drive pulley 14 and the idle pulley 18. The air motor 12 is driven to rotate by compressed air supplied from a joint 24 provided at the rear end of the grip portion 22 of the tool body 10, and drives the drive pulley 14 connected to the output shaft 12a of the air motor 12 to rotate, thereby driving the endless grinding belt 20. The belt-type grinding tool 1 is a tool for performing a grinding operation of a workpiece by pressing the thus-rotated endless grinding belt 20 against the workpiece.

The tool body 10 has a slide accommodating hole 26 extending in the direction of the longitudinal axis L of the pulley support lever 16, and a slide guide member 28 is inserted into the slide accommodating hole 26. The pulley support rod 16 is inserted into an inner hole of the slide guide member 28, and is held slidably in the longitudinal direction (vertical direction as viewed in the drawing) in the direction of the longitudinal axis L with respect to the tool body 10. A spring seat 30 and a spring 32 provided between the pulley support rod 16 and the spring seat 30 are inserted into the slide accommodating hole 26. A front spring receiving hole 34 extending forward from the rear end surface 16b of the pulley support lever 16 is formed, and a rear spring receiving hole 36 extending rearward from the front end surface 30a of the spring receiver 30 is formed. The spring 32 is held in the slide accommodating hole 26 such that the front end portion 32a is accommodated in the front spring accommodating hole 34 and the rear end portion 32b is accommodated in the rear spring accommodating hole 36. A spring support member accommodating space 40 that accommodates a spring support member 38 is provided behind the slide accommodating hole 26, and the spring support member 38 supports the spring receiver 30 from a rear position of the spring receiver 30. As described below, the spring support member 38 is attached to be pivotable about a pivot shaft 42 on the tool body 10.

As shown in fig. 2 to 4, the spring support member 38 is attached to the tool body 10 so as to be pivotable between a tension applying position (fig. 2) and a tension releasing position (fig. 4) about a pivot shaft 42, the pivot shaft 42 being located at a position displaced laterally (leftward as viewed in the drawing) from the longitudinal axis L. The spring support member 38 has a pressing support surface 46 that engages with the engagement portion 44 of the spring seat 30, and when the spring support member 38 is located at the tension application position (fig. 2), the pressing support surface 46 engages with the engagement portion 44 of the spring seat 30, and the spring seat 30 is pressed forward and supported. The spring 32 is compressed between the pulley support lever 16 and the spring support member 38 by the spring seat 30, and urges the pulley support lever 16 forward with respect to the tool body 10. The idle pulley 18 provided at the distal end portion 16a of the pulley support rod 16 is pressed against the inner circumferential surface of the endless grinding belt 20 by the biasing force of the spring 32, and a predetermined tension is applied to the endless grinding belt 20. When the drive pulley 14 is driven to rotate in this state, the endless grinding belt 20 is appropriately driven.

In the process of pivoting the spring bearing member 38 from the tension applying position (fig. 2) to the intermediate position (fig. 3) in the clockwise direction (first pivoting direction) as viewed in the drawing, the pressing bearing surface 46 acts like a cam to press the spring seat 30 further forward to further compress the spring 32. Therefore, in pivoting the spring support member 38 from the tension applying position to the intermediate position, it is necessary to apply the force required to further compress the spring 32 to the spring support member 38.

When the spring support member 38 is further pivoted from the intermediate position (fig. 3), the pressing support surface 46 is gradually displaced rearward, and the compressed spring 32 is gradually expanded. When the spring support member 38 is pivoted to the tension release position (fig. 4), the spring 32 is at its natural length and is in an uncompressed state, and the pulley support lever 16 is no longer pushed forward. Therefore, the tension applied to the endless grinding belt 20 is completely released. At this time, a certain gap is formed in the direction of the longitudinal axis L between the rear end portion 32b of the spring 32 having the natural length and the rear spring receiving hole 36 of the spring receiver 30. Accordingly, the pulley support lever 16 does not compress the spring 32 rearward by the margin, that is, does not receive the biasing force from the spring 32, and the rear end surface 16b thereof can be retracted to the position contacting the stepped portion 48 of the slide guide member 28. As shown in fig. 4, when the pulley support lever 16 is retracted, a gap is formed between the endless grinding belt 20 and the idle pulley 18 or the drive pulley 14, and the endless grinding belt 20 can be removed.

When tension is applied again to the endless grinding belt 20, the spring bearing member 38 is pivoted counterclockwise (second pivot direction) as viewed in the drawing from the tension releasing position (fig. 4), the spring seat 30 is pressed forward by the pressing support surface 46, and the spring bearing member 38 is pivoted to the tension applying position (fig. 2). The spring 32 is compressed by the spring seat 30, and the pulley support lever 16 is pressed forward by the biasing force of the spring 32. The endless grinding belt 20 is pressed by the idler pulley 18 and is in a state of being given tension.

As shown in fig. 2 to 4, while the spring support member 38 pivots between the tension applying position and the tension releasing position, the spring seat 30 is maintained in a state in which at least a part thereof is housed in the slide housing hole 26. Thus, the space between the pulley support lever 16 and the spring seat 30 in which the spring 32 is disposed does not directly communicate with the outside, and therefore, foreign matter such as dust can be prevented from entering the inside. Further, the foreign matter catching groove 50 is formed on the side surface of the spring seat 30, and even if foreign matter enters between the spring seat 30 and the slide guide member 28, the foreign matter is caught in the foreign matter catching groove 50, and the foreign matter does not continue to enter.

As shown in fig. 6, the tool body 10 is provided with: an upper front surface opening 52 through which an upper traveling portion 20a of the endless grinding belt 20 stretched over the drive pulley 14 and the idler pulley 18 passes; a lower front opening 54 through which the lower traveling part 20b of the endless grinding belt 20 passes; and a side opening 56 that is connected to the upper front opening 52 and the lower front opening 54 and that opens so as to expose the side surface 14a of the drive pulley 14. A cover 58 is attached to the spring support member 38 by a fixing screw 60, and the cover 58 pivots together with the pivoting of the spring support member 38 to open and close the side opening 56. As shown in fig. 5, when the spring bearing member 38 is located at the tension applying position, the cover 58 is closed so as to cover the side opening 56 of the tool body 10, thereby restricting access to the drive pulley 14. As shown in fig. 6, when the spring support member 38 is located at the tension releasing position, the cover 58 is opened laterally, and the side opening 56 is exposed so as to be accessible to the drive pulley 14. This enables the endless grinding belt 20 to be detached from or attached to the drive pulley 14 via the side opening 56, and enables the endless grinding belt 20 to be replaced. The cover 58 does not necessarily have to be attached to the spring support member 38 and may be attached to the tool body 10 separately from the spring support member 38.

As shown in fig. 7, the pressing support surface 46 of the spring support member 38 is formed as an inclined plane inclined with respect to the longitudinal axis L in a state where the spring support member 38 is located at the tension applying position. The engaging portion 44 of the spring bearing 30 that is in contact with the pressing support surface 46 is formed as an inclined portion that is a portion of the conical surface 62 centered on the long-side axis L. The engaging portion 44 is shaped such that the inclination angle thereof is the same as the inclination angle of the pressing support surface 46. By forming the engaging portion 44 of the spring seat 30 with the conical surface 62, the inclination angle of the engaging portion 44 is the same as the inclination angle of the pressing support surface 46 regardless of the rotational position about the longitudinal axis L of the spring seat 30. The shape of the pressing support surface 46 of the spring support member 38 and the engaging portion 44 of the spring seat 30 is set such that a normal line (e.g., the normal line X, Y) at any one contact point (e.g., the contact point A, B) with the spring seat 30 on the pressing support surface 46 passes on the opposite side (the left side of the pivot axis R as viewed in the drawing) from the long-side axis L with respect to the pivot axis R. Therefore, the line F of action of the force that the pressing support surface 46 of the spring support member 38 receives from the engagement portion 44 of the spring receiver 30 passes on the side where the spring support member 38 generates a moment that pivots the spring support member 38 in the counterclockwise direction (second pivot direction) with respect to the pivot axis R. Thereby, when the spring support member 38 is located at the tension applying position (fig. 2), a rotational moment in a direction (second pivot direction) away from the tension releasing position (fig. 4) is received. At this time, the cover 58 fixed to the spring bearing member 38 abuts against the tool body 10, and therefore the spring bearing member 38 is held at the tension applying position.

In the second embodiment of the present invention, as shown in fig. 8, the pressing support surface 146 of the spring support member 138 and the engagement portion 144 of the spring seat 130 are different in structure from the belt type grinding tool 1 of the first embodiment. Specifically, the pressing support surface 146 of the spring support member 138 and the engagement portion 144 of the spring seat 130 are shaped such that the normal line X 'at the contact point a' passes on the opposite side of the long-side axis L with respect to the pivot axis R, and the normal line Y 'at the contact point B' passes on the same side of the long-side axis L with respect to the pivot axis R. At this time, a moment of pivoting in the counterclockwise direction (second pivoting direction) by the force received at the contact point a 'acts on the spring support member 138, and a moment of pivoting in the clockwise direction (first pivoting direction) by the force received at the contact point B' acts thereon. Therefore, the above-described counteracting moment is counterbalanced in the spring support member 138, the line F ' of action of the force received by the pressing support surface 146 of the spring support member 138 from the engagement portion 144 of the spring seat 130 passes on the pivot axis R, and the spring support member 138 is held at the tension application position in a state where the pressing support surface 146 and the engagement portion 144 are in contact at least at the contact points a ' and B '. Even if the pivotal range of the spring bearing member 138 is not restricted by the abutment of the cover 158 with the tool main body 110 or the like, the spring bearing member 138 is held at the tension applying position by the urging force of the spring 132 received from the spring seat 130.

In the belt-type grinding tool of the present invention, the

spring support members

38, 138 for forming a state in which tension is applied to the endless grinding belt 20 are held at the tension application positions by the urging forces of the springs 32, 132 received via the spring seats 30, 130. Therefore, it is not necessary to provide a separate mechanism such as a hook for fixing the

spring support members

38 and 138 or the

covers

58 and 158 to the

tool bodies

10 and 110 in order to hold the

spring support members

38 and 138 at the tension applying positions.

In the above embodiment, the shapes of the pressing support surfaces 46 and 146 of the

spring support members

38 and 138 and the

engagement portions

44 and 144 of the spring seats 30 and 130 are linearly inclined with respect to the longitudinal axis L, but may be other shapes such as an eccentric arc. In addition, the pivot axis R of the

spring support member

38, 138 can also be set on the long axis L or on the right side as viewed in the drawing of the long axis L. In the above embodiment, when the

spring support members

38, 138 are in the tension release position, the springs 32, 132 are extended to a natural length, but a slight compression may remain. Further, instead of the air motor, an electric motor may be used as the drive source.

Description of the reference numerals

A belt type grinding tool 1; a tool body 10; a pneumatic motor 12; an output shaft 12 a; a drive pulley 14; side surface part 14 a; a pulley support rod 16; a front end portion 16 a; a rear end face 16 b; an idler pulley 18; an endless grinding belt 20; an upper traveling portion 20 a; a lower traveling portion 20 b; a grip portion 22; a joint 24; a slide accommodating hole 26; a slide guide member 28; a spring seat 30; a front end face 30 a; a spring 32; the front end portion 32 a; a rear end portion 32 b; a front spring receiving hole 34; a rear spring receiving hole 36; a spring support member 38; a spring support member housing space 40; a pivot shaft 42; an engaging portion 44; the pressing support surface 46; a step portion 48; a foreign matter catching groove 50; an upper front opening 52; a lower front opening 54; a side opening 56; a cover 58; a set screw 60; a conical surface 62; a tool body 110; a spring seat 130; a spring support member 138; an engaging portion 144; the press support surface 146; a cover 158; a long side axis L; a pivot axis R.

Claims

1. A belt-type grinding tool is provided with:

a tool body;

a drive pulley provided in the tool body and driven to rotate by a motor;

an idle pulley set at a position separated forward from the drive pulley, and having an endless grinding belt stretched between the idle pulley and the drive pulley;

a pulley support rod having a front end portion rotatably supporting the idle pulley, the pulley support rod extending rearward from the front end portion and slidably supported by the tool body;

a spring that urges the pulley support lever forward with respect to the tool body, and that urges the idler pulley supported by the pulley support lever forward to press the endless grinding belt, thereby applying tension to the endless grinding belt;

a spring seat supporting a rear end portion of the spring; and

a spring support member that is attached to the tool body so as to be pivotable about a pivot axis and that has a pressing support surface that contacts an engagement portion of the spring seat, the spring support member being pivotable between a tension application position at which the pressing support surface presses the engagement portion to compress and support the spring between the pressing support surface and the pulley support lever, thereby forming a state in which the idler pulley applies tension to the endless grinding belt, and a tension release position at which the pressing support surface is pivoted in a first pivot direction so as to be displaced rearward from the tension application position, and the amount of compression of the spring is reduced, thereby reducing the tension applied to the endless grinding belt,

the pressing support surface and the engaging portion are shaped such that a normal line at any contact point on the pressing support surface with the engaging portion when the spring support member is located at the tension applying position passes on a side opposite to a long-side axis of the pulley support lever with respect to the pivot axis, and a line of action of a force received by the pressing support surface of the spring support member from the engaging portion of the spring seat passes on a side where a moment that pivots the spring support member in a second pivot direction opposite to the first pivot direction is generated with respect to the pivot axis when the spring support member is located at the tension applying position.

2. The belt grinding tool according to claim 1,

the pivot axis of the spring support member is located at a position offset from the long side axis.

3. The belt grinding tool according to claim 2,

the pressing support surface has an inclined plane inclined with respect to the long-side axis when the spring support member is located at the tension applying position,

the engaging portion of the spring seat has an inclined portion having an inclination angle substantially the same as the inclination plane when the spring support member is located at the tension applying position.

4. The belt grinding tool according to claim 3,

the engaging portion is a conical surface centered on the long-side axis, and the inclined portion constitutes a part of the conical surface.

5. The belt grinding tool according to any one of claims 1 to 4,

the tool body has: a spring support member housing space that houses at least a part of the spring support member; and a slide accommodating hole that communicates with the spring bearing member accommodating space, holds the pulley support rod and the spring seat slidably in a direction of a long side axis of the pulley support rod, and accommodates the spring set between the pulley support rod and the spring seat,

when the spring support member pivots between the tension applying position and the tension releasing position, at least a portion of the spring seat slides relative to the slide accommodating hole in a state of being always accommodated in the slide accommodating hole.

6. The belt grinding tool according to claim 5,

the spring seat has a side surface that slides relative to the slide accommodating hole, and a foreign matter catching groove is formed in the side surface.

7. The belt grinding tool according to any one of claims 1 to 4,

the belt type grinding tool further comprises a cover attached to the spring support member,

the tool body further has: an upper front surface opening through which an upper traveling portion of the endless grinding belt stretched between the drive pulley and the idler pulley passes; a lower front opening through which a lower traveling portion of the endless grinding belt passes; and a side opening connected to the upper front opening and the lower front opening and opened to expose a side surface of the drive pulley,

the cover covers the side opening when the spring bearing member is in the tension applying position, and exposes the side opening to be accessible to the drive pulley when the spring bearing member is in the tension releasing position, so that the endless grinding belt can be attached to or detached from the drive pulley through the side opening.