JP6568997B2 - Belt grinding tool - Google Patents

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 against the object.

  The belt-type grinding tool includes a drive pulley that is rotationally driven by a motor, an idle pulley that is rotatably attached, and an endless grinding belt that is wound around the drive pulley and the idle pulley. This is a grinding tool for grinding an object by bringing an endless grinding belt that is rotationally driven along with the rotation of the object into contact with the object. A pulley support bar that supports the idle pulley is slidably held in a front-rear direction on a tool body provided with a drive pulley, and is urged forward by a spring provided in the tool body. Appropriate tension is applied to the endless grinding belt wound around the drive pulley and the idle pulley by the biasing force of the spring.

  The endless grinding belt is a consumable item and needs to be replaced when it is worn to some extent after grinding. When exchanging, normally, the pulley support bar is pushed backward against the urging force of the spring, the pulley support bar is kept in the retracted position by the lock mechanism, and the cover that covers the drive pulley is removed. The endless grinding belt is removed and attached. (Patent Document 1)

  However, in the replacement operation of the endless grinding belt as described above, the pulley support bar must be pushed so as to further compress the spring that is already compressed and generates a biasing force in order to apply tension to the endless grinding belt. Therefore, a relatively large force was required for the operation. Therefore, a belt-type grinding tool that does not require such a large force has been developed (Patent Document 2). In this belt-type grinding tool, a spring support member that supports a spring so as to apply tension to the endless grinding belt can be pivoted so that the support surface supporting the spring moves backward. By retracting, the compression amount of the spring is reduced, and the idle pulley can be easily retracted together with the pulley support bar. As a result, the pulley support bar can be pushed in with a smaller force than that disclosed in Patent Document 1, and the endless grinding belt can be easily replaced.

JP 2004-58216 A JP 2014-166668 A

  However, in the belt-type grinding tool as shown in the cited document 2, the spring support member that supports the spring receives a biasing force from the spring in a state in which the spring is compressed, so that the pressing support surface moves backward. Receiving a rotational moment that pivots. Therefore, in order to maintain the state where the spring is compressed, it is necessary to separately provide a mechanism such as a hook for fixing the spring support member to the tool body.

  SUMMARY OF THE INVENTION In view of the above-described problems of the prior art, an object of the present invention is to provide a belt-type grinding tool in which a spring support member is prevented from pivoting in a direction in which spring compression is released by a biasing force received from the spring. And

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 set at a position separated forward from the drive pulley and stretches an endless grinding belt between the drive pulley;
A pulley support bar having a front end portion that rotatably supports the idle pulley, extending rearward from the front end portion and slidably supported by the tool body;
The pulley support bar is urged forward with respect to the tool body, and an idle pulley supported by the pulley support bar presses the endless grinding belt forward to apply tension to the endless grinding belt. Spring and
A spring seat engaged with the rear end of the spring;
A spring support member attached to the tool body so as to be pivotable about a pivot axis and having a pressing support surface that comes into contact with an engaging portion of the spring seat, the pressing support surface pressing the engaging portion A tension applying position where the idle pulley applies tension to the endless grinding belt by compressing and supporting the spring with the pulley support bar, and the pressing support surface from the tension applying position. It is pivotable between a tension release position that pivots in the first pivoting direction so as to be displaced rearward, thereby reducing the compression amount of the spring and reducing the tension applied to the endless grinding belt. A spring support member;
With
When the spring support member is in the tension applying position, a line of action of the force that the pressing support surface of the spring support member receives from the engaging portion of the spring seat is the spring support member with respect to the pivot axis. The pressing support surface and the engaging portion are shaped so as to pass on a side that generates a moment that pivots the second pivotal direction in the second pivotal direction opposite to the first pivotal direction or on the pivot axis. In addition, a belt-type grinding tool is provided.

  In the belt-type grinding tool, when the spring support member is in the tension applying position, the line of action of the force received by the spring support member from the spring seat pivots in the second pivot direction (that is, the direction toward the tension applying position). It passes through the side where the moment to be moved is generated or on the pivot axis, so that no moment is generated in the first pivot direction (that is, the direction toward the tension release position). Therefore, it is possible to prevent the spring support member from pivoting from the tension applying position toward the tension releasing position due to the urging force of the spring, and the spring can be maintained in a compressed state. Note that the “tension release position” here does not mean only the state in which the compression of the spring is completely lost and no tension is applied to the endless grinding belt, but the amount of compression of the spring is reduced. Includes a state in which the compression is still left and a weak tension is applied to the endless grinding belt.

Preferably,
The pivot axis of the spring support member is offset from the longitudinal axis of the pulley support bar;
A normal line at a contact point on the pressing support surface with which the engaging portion of the spring seat contacts when the spring support member is in the tension applying position is opposite to the longitudinal axis with respect to the pivot axis. The pressing support surface and the engaging portion can be shaped so as to pass through the same.

  More preferably, when the spring support member is in the tension applying position, the pressing support surface and the engaging portion come into contact at a contact point other than the contact point, and the pressing at the other contact point is performed. The pressing support surface and the engagement portion may be shaped such that a normal to the support surface passes through the same side of the longitudinal axis as the pivot axis.

  With this 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 in the tension applying position;
The engagement portion of the spring seat may have an inclined portion having substantially the same inclination angle as the inclined plane when the spring support member is in the tension applying position.

  With such a configuration, the portions having the same inclination angle come into contact with each other, so that the spring support member can be held in a more stable state at the tension applying position.

  More preferably, the engaging portion may be a conical surface centered on the longitudinal axis, and the inclined portion may constitute a part of the conical surface.

  With such a configuration, the engaging portion of the spring seat can always properly contact the pressing support surface of the spring support member regardless of the rotational position around the longitudinal axis of the spring seat.

Preferably,
The tool main body communicates with a spring support member accommodating space for accommodating at least a part of the spring support member, and the spring support member accommodating space, and the pulley support bar and the spring seat are connected to the longitudinal axis of the pulley support bar. A sliding housing hole that holds the spring set between the spring support member and the spring seat, and slidably holds in a direction.
When the spring support member pivots between the tension applying position and the tension releasing position, the sliding accommodation is performed in a state where at least a part of the spring seat is always accommodated in the sliding accommodation hole. It can be made to slide with respect to the hole.

  With this configuration, the spring support member housing space and the sliding housing hole are blocked by the spring seat, so that foreign matters such as dust and dirt enter the sliding housing hole from the spring support member housing space side. Can be suppressed.

Preferably,
A cover attached to the spring support member;
An upper front opening through which the upper traveling portion of the endless grinding belt passes between the drive pulley and the idle pulley and a lower traveling portion through which the lower traveling portion of the endless grinding belt passes. A front opening, and a side opening that is connected to the upper front opening and the lower front opening and that opens to expose the side surface of the drive pulley.
The cover is configured to cover the side opening when the spring support member is in the tension applying position, and to expose the side opening when the spring support member is in the tension releasing position. A pulley can be accessible, and the endless grinding belt can be attached to or removed from the drive pulley through the side opening.

  Since the spring support member and the cover are integrated, the operation to release the tension of the endless grinding belt and the operation to open the cover and make the drive pulley accessible are completed in one operation. Can be performed more concisely. In addition, in order to enable the endless grinding belt to be driven to rotate, the spring support member must be in the tension applied position. At this time, the drive pulley is covered with a cover, so that the endless drive belt is exposed and the endless grinding belt is exposed. The grinding belt is not rotationally driven, and the risk of an operator's hand or the like being accidentally caught between the endless grinding belt and the drive pulley that is rotationally driven is reduced.

  Embodiments of a belt grinding tool according to the present invention will be described below with reference to the accompanying drawings.

It is a plane fragmentary sectional view which shows the principal part of the belt type grinding tool which concerns on one Embodiment of this invention in a cross section. It is the elements on larger scale of Drawing 1, and is a figure showing the state where the spring support member of a belt type grinding tool exists in a tension addition position. It is the elements on larger scale of Drawing 1, and is a figure showing the state where a spring support member is in an intermediate position. It is the elements on larger scale of Drawing 1, and is a figure showing the state where a spring support member exists in a tension release position. It is a side view of the belt type grinding tool of FIG. FIG. 2 is a side view of the belt-type grinding tool of FIG. 1, showing a state where a spring support member is in a tension release position and a cover is open. It is a figure which shows the force which a spring support member receives. It is a figure which shows the force which the spring support member receives of the belt type grinding tool which concerns on 2nd embodiment.

  As shown in FIG. 1, a belt-type grinding tool 1 according to an embodiment of the present invention extends from a tool body 10 that houses an air motor 12 and a drive pulley 14 to the front (upward in the figure) from the tool body 10. A pulley support bar 16 and an idle pulley 18 rotatably attached by a bearing at a front end portion 16a of the pulley support bar 16. An endless grinding belt 20 is provided between the drive pulley 14 and the idle pulley 18. Is to be hung around. The air motor 12 is rotationally driven by compressed air supplied from a joint 24 provided at the rear end of the grip portion 22 of the tool body 10, and rotationally drives a drive pulley 14 connected to the output shaft 12 a of the air motor 12. The endless grinding belt 20 is driven. The belt-type grinding tool 1 is a tool configured to perform grinding work on the work material by pressing the endless grinding belt 20 thus rotated against the work material.

  The tool body 10 has a sliding accommodation hole 26 extending in the direction of the longitudinal axis L of the pulley support bar 16, and a sliding guide member 28 is inserted into the sliding accommodation hole 26. The pulley support bar 16 is inserted into the inner hole of the sliding guide member 28 and is held so as to be slidable in the longitudinal direction (vertical direction as viewed in the figure) in the direction of the longitudinal axis L with respect to the tool body 10. . Further, a spring seat 30 and a spring 32 set between the pulley support bar 16 and the spring seat 30 are inserted into the sliding housing hole 26. The pulley support bar 16 is formed with a front spring accommodating hole 34 extending forward from the rear end face 16b, and the spring seat 30 is formed with a rear spring accommodating hole 36 extending rearward from the front end face 30a. Yes. The spring 32 is held in the sliding accommodation hole 26 such that the front end portion 32 a is accommodated in the front spring accommodation hole 34 and the rear end portion 32 b is accommodated in the rear spring accommodation hole 36. A spring support member accommodation space 40 for accommodating a spring support member 38 for supporting the spring seat 30 from its rear position is provided behind the slide accommodation hole 26. As will be described below, the spring support member 38 is pivotally mounted about a pivot shaft 42 on the tool body 10.

  As shown in FIG. 2-4, the spring support member 38 has a tension application position (FIG. 2) and a tension applied around the pivot shaft 42 that is shifted laterally (leftward in the figure) from the longitudinal axis L. It is attached to the tool body 10 so as to be pivotable between the release position (FIG. 4). The spring support member 38 has a pressing support surface 46 adapted to engage with the engaging portion 44 of the spring seat 30. When the spring supporting member 38 is in the tension applying position (FIG. 2), the pressing support surface 38 is pressed. The surface 46 engages with the engaging 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 bar 16 and the spring support member 38 via the spring seat 30 and urges the pulley support bar 16 forward with respect to the tool body 10. Due to the urging force of the spring 32, the idle pulley 18 provided at the front end portion 16 a of the pulley support bar 16 is pressed against the inner peripheral surface of the endless grinding belt 20, and a predetermined tension is applied to the endless grinding belt 20. When the drive pulley 14 is rotationally driven in this state, the endless grinding belt 20 is appropriately driven.

  In the process of pivoting the spring support member 38 clockwise (first pivotal direction) from the tension applying position (FIG. 2) to the intermediate position (FIG. 3), the pressing support surface 46 is like a cam. And the spring seat 30 is further pushed forward to further compress the spring 32. Therefore, when the spring support member 38 is pivoted from the tension applying position to the intermediate position, it is necessary to apply a force necessary for further compressing 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 accordingly. When the spring support member 38 is pivoted to the tension release position (FIG. 4), the spring 32 becomes a natural length and is no longer compressed, and the pulley support bar 16 is not pushed forward. Therefore, the tension applied to the endless grinding belt 20 is completely released. At this time, a constant gap is formed in the direction of the longitudinal axis L between the rear end portion 32 b of the spring 32 having a natural length and the rear spring accommodating hole 36 of the spring seat 30. As a result, the pulley support bar 16 does not compress the spring 32 toward the rear by this margin, that is, without receiving a biasing force from the spring 32, the rear end surface 16 b of the stepped portion 48 of the sliding guide member 28. It is possible to move back to the position where it hits. As shown in FIG. 4, when the pulley support bar 16 moves backward, 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 the tension is applied again to the endless grinding belt 20, the spring support member 38 is pivoted counterclockwise (second pivot direction) as viewed from the tension release position (FIG. 4), and the pressing support surface While the spring seat 30 is pressed forward by 46, it is pivoted to the tension applying position (FIG. 2). The spring 32 is compressed via the spring seat 30, and the pulley support bar 16 is pressed forward by the urging force of the spring 32. The endless grinding belt 20 is pressed by the idle pulley 18 and is in a state where tension is applied.

  As shown in FIG. 2-4, while the spring support member 38 pivots between the tension applying position and the tension releasing position, at least a part of the spring seat 30 is accommodated in the slide accommodating hole 26. Is maintained. As a result, the space in which the spring 32 between the pulley support bar 16 and the spring seat 30 is disposed does not directly communicate with the outside, so that foreign matters such as dust and dirt can enter the inside. Can be prevented. Further, a foreign matter catching groove 50 is formed on the side surface of the spring seat 30. Even if a foreign matter enters between the spring seat 30 and the sliding guide member 28, the foreign matter catching groove 50 catches the foreign matter. Thus, the foreign object does not enter further.

  As shown in FIG. 6, the tool body 10 includes an upper front opening 52 through which the upper traveling portion 20 a of the endless grinding belt 20 wound around the drive pulley 14 and the idle pulley 18 passes, and the endless grinding belt 20. A lower front opening 54 through which the lower traveling portion 20b passes, and a side opening 56 that is connected to the upper front opening 52 and the lower front opening 54 and opens to expose the side surface 14a of the drive pulley 14 are provided. Is provided. A cover 58 is attached to the spring support member 38 with a fixing screw 60. The cover 58 is also pivoted together with the pivot of the spring support member 38 to open and close the side opening 56. . As shown in FIG. 5, when the spring support member 38 is in the tension applying position, the cover 58 is closed so as to cover the side opening 56 of the tool body 10 and restricts access to the drive pulley 14. Yes. As shown in FIG. 6, when the spring support member 38 is in the tension release position, the cover 58 is open toward the side, and the side opening 56 is exposed so that the drive pulley 14 can be accessed. . As a result, the endless grinding belt 20 can be removed from or attached to the drive pulley 14 via the side opening 56, and the endless grinding belt 20 can be replaced. Note that the cover 58 is not necessarily attached to the spring support member 38 and pivoted together, but 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 an inclined plane that is inclined with respect to the longitudinal axis L in a state where the spring support member 38 is in the tension applying position. The engaging portion 44 of the spring seat 30 that contacts the pressing support surface 46 is an inclined portion that is a part of the conical surface 62 with the longitudinal axis L as the center. The engaging portion 44 is shaped so that its inclination angle is the same as the inclination angle of the pressing support surface 46. By making the engaging portion 44 of the spring seat 30 consist of the conical surface 62, the inclination angle of the engaging portion 44 of the pressing support surface 46 is independent of the rotational position about the longitudinal axis L of the spring seat 30. It becomes the same as the inclination angle. The pressing support surface 46 of the spring support member 38 and the engaging portion 44 of the spring seat 30 are normal (for example, normal) at any contact point (for example, contact points A and B) between the spring support 30 on the press support surface 46. X, Y) is also shaped so as to pass through the side opposite to the longitudinal axis L (left side of the pivot axis R in the figure) with respect to the pivot axis R. Therefore, the line of action F of the force that the pressing support surface 46 of the spring support member 38 receives from the engaging portion 44 of the spring seat 30 rotates the spring support member 38 counterclockwise with respect to the pivot axis R (second pivot direction). ) Passes through the side that causes the spring support member 38 to be pivoted. As a result, when the spring support member 38 is in the tension applying position (FIG. 2), it receives a rotational moment in the direction away from the tension releasing position (FIG. 4) (second pivot direction). At this time, since the cover 58 fixed to the spring support member 38 is in contact with the tool body 10, the spring support member 38 is held at the tension applying position.

  In the second embodiment of the present invention, as shown in FIG. 8, the configuration of the pressing support surface 146 of the spring support member 138 and the engaging portion 144 of the spring seat 130 is the belt-type grinding according to the first embodiment. Different from tool 1. Specifically, the normal line X ′ at the contact point A ′ passes through the opposite side of the longitudinal axis L with respect to the pivot axis R, while the normal line Y ′ at the contact point B ′ extends to the pivot axis R. On the other hand, the pressing support surface 146 of the spring support member 138 and the engaging portion 144 of the spring seat 130 are shaped so as to pass the same side as the longitudinal axis L. At this time, a moment that pivots counterclockwise (second pivot direction) by the force received at the contact point A ′ acts on the spring support member 138, and clockwise (first rotation) by the force received at the contact point B ′. A moment that pivots in the direction of pivoting will also act. Accordingly, in the spring support member 138, these opposing moments are antagonistic, and the action line F ′ of the force received by the pressing support surface 146 of the spring support member 138 from the engaging portion 144 of the spring seat 130 is on the pivot axis R. The pressure supporting surface 146 and the engaging portion 144 are held at the tension applying position in a state where they are in contact at least at the contact points A ′ and B ′. The spring support member 138 is held at the tension applying position by the urging force of the spring 132 received from the spring seat 130 without restricting the pivot range of the spring support member 138 by bringing the cover 158 into contact with the tool body 110 or the like. Is done.

  In the belt-type grinding tool according to the present invention, the spring support members 38 and 138 for applying tension to the endless grinding belt 20 are urged by the urging forces of the springs 32 and 132 received via the spring seats 30 and 130. It is held at the tension application position. Therefore, a 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 needs to be provided separately in order to hold the spring support members 38 and 138 in the tension applying position. Disappears.

  In the above embodiment, the pressing support surfaces 46 and 146 of the spring support members 38 and 138 and the engaging portions 44 and 144 of the spring seats 30 and 130 are shaped so as to incline linearly with respect to the longitudinal axis L. However, other shapes such as an eccentric arc can be used. It is also possible to set the pivot axis R of the spring support members 38, 138 on the longitudinal axis L or on the right side as viewed in the figure with respect to the longitudinal axis L. In the above embodiment, the springs 32 and 132 extend to the natural length when the spring support members 38 and 138 are in the tension release position, but some compression may remain. . Moreover, you may make it use an electric motor instead of an air motor as a drive source.

Belt-type grinding tool 1; tool body 10; air motor 12; output shaft 12a; drive pulley 14; side surface portion 14a; pulley support bar 16: front end portion 16a; 20a; lower traveling portion 20b; grip portion 22; joint 24; sliding accommodation hole 26; sliding guide member 28; spring seat 30; front end surface 30a; spring 32; front end portion 32a; Hole 34; rear spring accommodation hole 36; spring support member 38; spring support member accommodation space 40; pivot shaft 42; engagement portion 44; press support surface 46; step portion 48; Lower front opening 54; side opening 56; cover 58; fixing screw 60; conical surface 62;
Tool body 110; Spring seat 130; Spring support member 138; Engagement portion 144; Pressing support surface 146; Cover 158;
Longitudinal axis L; pivot axis R;

Claims (7)

A tool body;
A drive pulley provided in the tool body and driven to rotate by a motor;
An idle pulley that is set at a position separated forward from the drive pulley and stretches an endless grinding belt between the drive pulley;
A pulley support bar having a front end portion that rotatably supports the idle pulley, extending rearward from the front end portion and slidably supported by the tool body;
The pulley support bar is urged forward with respect to the tool body, and an idle pulley supported by the pulley support bar presses the endless grinding belt forward to apply tension to the endless grinding belt. Spring and
A spring seat engaged with the rear end of the spring;
A spring support member attached to the tool body so as to be pivotable about a pivot axis and having a pressing support surface that comes into contact with an engaging portion of the spring seat, the pressing support surface pressing the engaging portion A tension applying position where the idle pulley applies tension to the endless grinding belt by compressing and supporting the spring with the pulley support bar, and the pressing support surface from the tension applying position. It is pivotable between a tension release position that pivots in the first pivoting direction so as to be displaced rearward, thereby reducing the compression amount of the spring and reducing the tension applied to the endless grinding belt. A spring support member;
With
The normal line at any contact point with the engagement portion on the pressing support surface when the spring support member is in the tension applying position is the longitudinal axis of the pulley support bar with respect to the pivot axis. The pressing support surface and the engaging portion are shaped to pass the opposite side, and the pressing support surface of the spring supporting member is the spring when the spring supporting member is in the tension applying position. line of action of the force from the engaging portion of the seat is, causes a moment to pivot the second pivoting direction opposite to the first pivoting direction the spring support member relative該枢kinematic axis side It is to pass through the the belt-type grinding tool. Ru position near the該枢movement axis of the spring support member is shifted from the longitudinal axis, the belt-type grinding tool according to claim 1. The pressing support surface has an inclined plane inclined with respect to the longitudinal axis when the spring support member is in the tension applying position;
The belt-type grinding tool according to claim 2 , wherein the engaging portion of the spring seat has an inclined portion having substantially the same inclination angle as the inclined plane when the spring support member is in the tension applying position. The belt-type grinding tool according to claim 3 , wherein the engaging portion is a conical surface centered on the longitudinal axis, and the inclined portion constitutes a part of the conical surface. The tool main body communicates with a spring support member accommodating space for accommodating at least a part of the spring support member, and the spring support member accommodating space, and the pulley support bar and the spring seat are connected to the longitudinal axis of the pulley support bar. A sliding housing hole that holds the spring set between the spring support member and the spring seat, and slidably holds in a direction.
When the spring support member pivots between the tension applying position and the tension releasing position, the sliding accommodation is performed in a state where at least a part of the spring seat is always accommodated in the sliding accommodation hole. The belt-type grinding tool according to any one of claims 1 to 4 , wherein the belt-type grinding tool is configured to slide with respect to the hole. The belt-type grinding tool according to claim 5, wherein the spring seat has a side surface that slides with respect to the sliding accommodation hole, and a foreign matter catching groove is formed on the side surface. A cover attached to the spring support member;
An upper front opening through which the upper traveling portion of the endless grinding belt passes between the drive pulley and the idle pulley and a lower traveling portion through which the lower traveling portion of the endless grinding belt passes. A front opening, and a side opening that is connected to the upper front opening and the lower front opening and that opens to expose the side surface of the drive pulley.
The cover is configured to cover the side opening when the spring support member is in the tension applying position, and to expose the side opening when the spring support member is in the tension releasing position. The belt-type grinding tool according to any one of claims 1 to 6, wherein the belt-type grinding tool is configured such that the pulley is accessible and the endless grinding belt can be attached to or detached from the drive pulley through the side opening.

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