Tool

Abstract

To provide a technique which can sufficiently suppress backlash of a mounting section with respect to a mounted section.SOLUTION: A tool includes: a prime mover; a power transmission mechanism; a housing; a tip tool holding section which holds a tip tool; a cover which has a body section for covering at least a part of the tip tool holding section and a mounting section having a substantially cylindrical shape along a rotary shaft of the tip tool holding section; a mounted section which is fixed to the housing and in which the mounting section is mounted; and a lock mechanism which can fix the mounting section to the mounted section. The mounted section slidably accepts the mounting section along the rotary shaft and rotatably accepts the mounting section around the rotary shaft. The mounted section is provided with a mounting groove along a circumferential direction of the rotary shaft. In the mounting groove, an elastic member is mounted to be pressed in a radial direction of the rotary shaft by the mounting section and the mounted section. A ratio of a width of the elastic member in an axial direction of the rotary shaft to a width of the elastic member in the radial direction is larger than 1.0.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed herein relates to tools. [Background technology]

[0002] Patent Document 1 discloses a tool including a prime mover, a power transmission mechanism connected to the prime mover, a housing that accommodates the prime mover and the power transmission mechanism, a cover that includes a tool holder connected to the power transmission mechanism and that holds a tool tip, a main body that covers at least a part of the tool holder, and a mounting part having a substantially cylindrical shape along the rotation axis of the tool holder, a mounting part that is fixed to the housing and to which the mounting part is attached, and a locking mechanism that switches between a state in which the mounting part is fixed to the mounting part and a state in which the mounting part is not fixed. The mounting part is configured to receive the mounting part slidably along the rotation axis and to receive the mounting part rotatably around the rotation axis. The mounting part is provided with a mounting groove that is aligned with the circumferential direction of the rotation axis. An elastic member that is pressed in the radial direction of the rotation axis by the mounting part and the mounting part is attached to the mounting groove. The ratio of the width of the elastic member in the axial direction of the rotation axis to the width of the elastic member in the radial direction is about 1.0. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] European Patent Application Publication No. 2209591 Summary of the Invention [Problem to be solved by the invention]

[0004] In the tool of Patent Document 1, in order to suppress the rattling of the mounting part relative to the mounted part when the mounting part is slid or rotated relative to the mounted part, a mounting groove is provided in the mounted part, and an elastic member is provided in the mounting groove. The elastic member supports the mounting part in the radial direction relative to the mounted part, thereby suppressing the rattling of the mounting part relative to the mounted part. In this configuration, the larger the width of the elastic member in the axial direction, the wider the range in which the elastic member can support the mounting part, so that rattling of the mounting part is effectively suppressed. On the other hand, if the width of the elastic member in the radial direction is too large, the elastic member may deform significantly in the radial direction, so that rattling of the mounting part may not be suppressed. In the tool of Patent Document 1, the ratio of the width of the elastic member in the axial direction to the width of the elastic member in the radial direction is about 1.0, so that when the width of the elastic member in the axial direction is increased, the width of the elastic member in the radial direction also increases to the same extent. Therefore, even if the width of the elastic member in the axial direction is increased, the width of the elastic member in the radial direction becomes excessively large, so that rattling of the mounting part relative to the mounted part may not be sufficiently suppressed. The present specification provides a technique capable of sufficiently suppressing rattling of a mounting portion relative to a mounted portion.

[0005] In this specification, the numerical values ​​(width, ratio, etc.) relating to the dimensions of the elastic member are described with reference to the elastic member in a state where no load is applied thereto due to pressing or the like. [Means for solving the problem]

[0006] The tool disclosed in this specification includes a prime mover, a power transmission mechanism connected to the prime mover, a housing that accommodates the prime mover and the power transmission mechanism, a cover that includes a tool holder connected to the power transmission mechanism and that holds a tool tip, a main body that covers at least a part of the tool holder, and a mounting part having a substantially cylindrical shape along a rotation axis of the tool holder, a mounting part that is fixed to the housing and to which the mounting part is attached, and a locking mechanism that switches between a state in which the mounting part is fixed to the mounting part and a state in which the mounting part is not fixed. The mounting part is configured to receive the mounting part slidably along the rotation axis and to receive the mounting part rotatably around the rotation axis. The mounting part is provided with a mounting groove that is aligned with the circumferential direction of the rotation axis. An elastic member that is pressed in the radial direction of the rotation axis by the mounting part and the mounting part is attached to the mounting groove. A ratio of a width of the elastic member in the axial direction of the rotation axis to a width of the elastic member in the radial direction is greater than 1.0.

[0007] According to the above configuration, the ratio of the width of the elastic member in the axial direction to the width of the elastic member in the radial direction is greater than 1.0. Therefore, the width of the elastic member in the axial direction can be increased without excessively increasing the width of the elastic member in the radial direction. This makes it possible to suppress large deformation of the elastic member in the radial direction and to support the mounting portion over a wide range by the elastic member. Therefore, rattling of the mounting portion relative to the mounted portion can be sufficiently suppressed. [Brief description of the drawings]

[0008] [Figure 1] 1 is a vertical cross-sectional view of a grinder 2 according to an embodiment of the present invention. [Diagram 2] 1 is a perspective view of a wheel cover 12 of a grinder 2 according to an embodiment, as viewed from above on the front right. [Diagram 3] 1 is a top view of a wheel cover 12 of a grinder 2 according to an embodiment of the present invention. [Figure 4]1 is a cross-sectional view of the band portion 44, the cover mounting portion 50, and the rubber ring 56 in a state where the wheel cover 12 is attached to the cover mounting portion 50 of the grinder 2 according to the embodiment, taken perpendicular to the circumferential direction of the axis A. [Diagram 5] 1 is a perspective view of the front portion of the grinder 2 according to the embodiment, seen from below and rear left, showing a state before the wheel cover 12 is attached to the cover attachment portion 50. FIG. [Figure 6] 2 is a perspective view of the rubber ring 56 of the grinder 2 according to the embodiment, as viewed from above on the front right. FIG. [Figure 7] 2 is a cross-sectional view of the rubber ring 56 of the grinder 2 according to the embodiment, taken along a line perpendicular to the circumferential direction of the axis A. FIG. [Figure 8] 1 is a cross-sectional view of a grinder 2 according to an embodiment of the present invention. [Figure 9] 1 is a view of the front portion of the grinder 2 according to the embodiment, seen from above and to the front right, showing the state before the wheel cover 12 is attached to the cover attachment portion 50. FIG. [Figure 10] 1 is a view of the front portion of the grinder 2 according to the embodiment, showing a state in which the wheel cover 12 is in the attachment / detachment position after the wheel cover 12 has been attached to the cover attachment portion 50, as viewed from above the front right. [Figure 11] 1 is a view of the front portion of the grinder 2 according to the embodiment, showing a state in which the wheel cover 12 is in a fixed position after the wheel cover 12 is attached to the cover attachment portion 50, as viewed from above the front right. [Figure 12] 13 is a cross-sectional view of a rubber ring 56 of a grinder 2 according to a modified example, the cross-sectional view being perpendicular to the circumferential direction of an axis A. FIG. [Figure 13] 13 is a cross-sectional view of a rubber ring 56 of a grinder 2 according to another modified example, the cross-sectional view being perpendicular to the circumferential direction of the axis A. FIG. [Figure 14] 13 is a diagram showing a plurality of O-rings 72, 74 provided in place of the rubber ring 56 in a grinder 2 according to yet another modified example, as viewed in a cross section perpendicular to the circumferential direction of the axis A. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Representative and non-limiting embodiments of the present invention are described in detail below with reference to the drawings. This detailed description is intended simply to provide those skilled in the art with details for implementing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Additionally, the additional features and inventions disclosed can be used separately or together with other features and inventions to provide further improved tools.

[0010] In addition, the combinations of features and steps disclosed in the following detailed description are not essential for implementing the present invention in the broadest sense, but are specifically described only to illustrate representative embodiments of the present invention. Furthermore, the various features of the following representative embodiments and the various features described in the claims do not have to be combined in the exact manner of the embodiments described herein or in the order listed in order to provide additional and useful embodiments of the present invention.

[0011] All features described in the specification and / or claims are intended to be disclosed individually and independently of one another as limitations to the specific features described in the original disclosure and claims, apart from the configuration of features described in the examples and / or claims. Furthermore, all numerical ranges and group or aggregate descriptions are intended to disclose intermediate configurations thereof as limitations to the specific features described in the original disclosure and claims.

[0012] In one or more embodiments, a ratio of the width of the elastic member in the axial direction to an overlap width of the mounting portion and the mounted portion in the axial direction may be 0.2 or greater, where "overlap width" refers to the overlap width when the mounting portion is mounted to the mounted portion.

[0013] The ratio of the width of the elastic member in the axial direction to the overlap width can be said to be an index showing the relative width of the range in which the elastic member can support the mounting portion, relative to the overlap width. The larger this ratio is, the wider the range in which the elastic member can support the mounting portion, so that wobbling of the mounting portion relative to the mounted portion is effectively suppressed. In conventional tools, the ratio of the width of the elastic member in the axial direction to the overlap width is less than 0.2 at most. According to the above configuration, the ratio of the width of the elastic member in the axial direction to the overlap width is 0.2 or more. Therefore, wobbling of the mounting portion relative to the mounted portion can be suppressed more effectively than before.

[0014] In one or more embodiments, the attachment groove and the elastic member may each be provided continuously and uninterrupted along the circumferential direction.

[0015] According to the above configuration, the gap between the mounting part and the mounted part is sealed by the elastic member. This makes it possible to prevent dust generated when the tool tip processes the workpiece from passing between the mounting part and the mounted part. Furthermore, according to the above configuration, the elastic member is formed in one piece, so the number of parts of the tool can be reduced.

[0016] In one or more embodiments, the mounting portion may be provided with a protruding portion that protrudes from the mounting portion toward the mounted portion. The mounted portion may be provided with a guide groove that regulates movement of the protruding portion in the axial direction. A ratio of the width of the elastic member in the radial direction to the width of the protruding portion in the radial direction may be greater than 1.0.

[0017] From the viewpoint of improving the durability of the elastic member, it is desirable to increase the thickness of the elastic member (i.e., the width of the elastic member in the radial direction) to a certain extent. In conventional tools, the ratio of the width of the elastic member in the radial direction to the width of the protruding portion in the radial direction was at most about 1.0. For this reason, the thickness of the elastic member was relatively small, and the durability of the elastic member could be poor. According to the above configuration, since the ratio of the width of the elastic member in the radial direction to the width of the protruding portion in the radial direction is greater than 1.0, the thickness of the elastic member can be made relatively large. Therefore, the durability of the elastic member can be improved.

[0018] In one or more embodiments, the mounting portion may be provided with a protruding portion that protrudes from the mounting portion toward the mounted portion. The mounted portion may be provided with a guide groove that restricts movement of the protruding portion in the axial direction. A portion of the guide groove may be defined by the elastic member.

[0019] In a configuration in which the guide groove restricts the axial movement of the protrusion, if the mounting groove and the guide groove are spaced apart in the axial direction, the mounted portion may become large in the axial direction. According to the above configuration, the elastic member (i.e., the mounting groove) and the guide groove are adjacent to each other in the axial direction, so the mounted portion can be made small in the axial direction.

[0020] In one or more embodiments, the elastic member may include a first surface that is substantially perpendicular to the axial direction and faces the mounting portion when the mounting portion is mounted to the mounted portion, a second surface that is substantially perpendicular to the axial direction and faces the opposite side to the first surface, a third surface that is substantially perpendicular to the radial direction and faces the outside of the mounting groove, and a fourth surface that is substantially perpendicular to the radial direction and faces the inside of the mounting groove. The elastic member may have a substantially rectangular shape in a cross section perpendicular to the circumferential direction, defined by the first surface, the second surface, the third surface, and the fourth surface.

[0021] Between the mounting groove and the mounting portion, a space (also called a mounting space) for arranging the elastic member is formed. In general, the mounting space has a substantially rectangular shape in a cross section perpendicular to the circumferential direction. If the shape of the elastic member does not conform to the shape of the mounting space (for example, if the elastic member has a substantially circular shape in a cross section perpendicular to the circumferential direction), a relatively large gap is generated between the mounting groove (or mounting portion) and the elastic member. If this gap is large, the elastic member may be significantly deformed when the elastic member is pressed by the mounting portion and the mounted portion, so that rattling of the mounting portion relative to the mounted portion may not be suppressed. According to the above configuration, the elastic member has a substantially rectangular shape in a cross section perpendicular to the circumferential direction. That is, since the elastic member has a shape that conforms to the shape of the mounting space, the gap generated between the mounting groove (or mounting portion) and the elastic member can be reduced. This makes it possible to suppress the elastic member from being significantly deformed when the elastic member is pressed by the mounting portion and the mounted portion. Therefore, rattling of the mounting portion relative to the mounted portion can be suppressed.

[0022] In one or more embodiments, a connection portion between the first surface and the third surface may have a chamfered shape.

[0023] If the connection portion between the first surface and the third surface does not have a chamfered shape, the attachment portion will abut perpendicularly against the first surface during the process of attaching the attachment portion to the attached portion. At this time, even if the attachment portion is pushed in the attachment direction, no force is generated to compress the elastic member in the radial direction. For this reason, the elastic member may not properly enter the inside of the attachment portion, which may cause annoyance to the user performing the attachment work. According to the above configuration, the connection portion between the first surface and the third surface has a chamfered shape. During the process of attaching the attachment portion to the attached portion, the attachment portion abuts against the chamfered shape. Since the chamfered shape has a shape that expands in diameter toward the attachment direction of the attachment portion, when the attachment portion is pushed in the attachment direction, a radial reaction force is generated between the attachment portion and the elastic member. This reaction force compresses the elastic member and causes it to enter the inside of the attachment portion. Therefore, according to the above configuration, the elastic member enters the inside of the attachment portion relatively easily, which reduces the annoyance felt by the user performing the attachment work.

[0024] In one or more embodiments, at least one of a connection portion between the first surface and the fourth surface and a connection portion between the second surface and the fourth surface may not have a chamfered shape.

[0025] When the mounting portion slides against the elastic member, the elastic member may be pulled by the mounting portion, causing the elastic member to fall off from the mounting groove. According to the above configuration, at least one of the connection portion between the first surface and the fourth surface and the connection portion between the second surface and the fourth surface has a so-called pin-angle shape. Even if the elastic member is pulled by the mounting portion, the pin-angle shape is caught on the bottom surface or wall surface of the mounting groove, so that the elastic member is retained in the mounting groove. Therefore, it is possible to prevent the elastic member from falling off from the mounting groove.

[0026] (Example) As shown in FIG. 1, the grinder 2 includes a motor housing 4, a rear housing 6, a gear housing 8, a bearing box 10, and a wheel cover 12.

[0027] A motor 14 is accommodated inside the motor housing 4. The motor 14 has an output shaft 16 that extends in the front-rear direction. The output shaft 16 is rotatably supported by the motor housing 4 via bearings 18 and 20.

[0028] The rear housing 6 is attached to the rear of the motor housing 4. A power supply circuit 22 is accommodated inside the rear housing 6. Power is supplied to the power supply circuit 22 from an external power source via a power cord 24. When the user turns on a switch 26 (see FIG. 5), the power supply circuit 22 supplies power to the motor 14, and when the user turns off the switch 26, the power supply circuit 22 stops supplying power to the motor 14. The motor 14 rotates the output shaft 16 by the power supplied from the power supply circuit 22.

[0029] The gear housing 8 is attached to the front of the motor housing 4. The gear housing 8 contains a first bevel gear 28 and a second bevel gear 30 arranged to mesh with each other. The first bevel gear 28 is fixed to the front end of the output shaft 16. The second bevel gear 30 is fixed to the upper part of a spindle 32 extending in the vertical direction. Hereinafter, the first bevel gear 28 and the second bevel gear 30 are collectively referred to simply as a bevel gear 34. The bevel gear 34 is a reduction mechanism that reduces the rotation of the motor 14 and transmits it to the spindle 32. The gear housing 8 holds the upper end of the spindle 32 via a bearing 36. In addition, a shaft lock 38 (see FIG. 9) is provided on the upper surface of the gear housing 8. When a user presses the shaft lock 38 downward, the second bevel gear 30 is prohibited from rotating, and the spindle 32 is prohibited from rotating.

[0030] The bearing box 10 is attached below the gear housing 8. The bearing box 10 holds the second bevel gear 30 via a bearing 40. The bearing box 10 also holds the spindle 32 via a bearing 41. The spindle 32 can rotate relative to the bearing box 10 around an axis A along the vertical direction. A grinding wheel GW can be attached to the lower part of the spindle 32 via an inner flange IF and an outer flange OF. In the grinder 2, when the output shaft 16 of the motor 14 rotates, the grinding wheel GW rotates together with the spindle 32 around the axis A, thereby grinding the workpiece. The spindle 32 can also be referred to as a tip tool holding part that holds the grinding wheel GW, which is a tip tool. In the following description, the motor housing 4, the rear housing 6, the gear housing 8, and the bearing box 10 are collectively referred to simply as the housing 42.

[0031] A wheel cover 12 is attached to the bearing box 10. As shown in FIG.

[0032] The band portion 44 has a generally cylindrical shape extending in the vertical direction. As shown in FIG. 3, the inner peripheral surface of the band portion 44 is formed with anti-slip ribs 44a, 44b, 44c, 44d, and 44e that protrude toward the inside in the radial direction of the axis A and have a longitudinal direction in the circumferential direction of the axis A. The anti-slip ribs 44a, 44b, 44c, 44d, and 44e are aligned in the vertical direction. Among the anti-slip ribs 44a, 44b, 44c, 44d, and 44e, the anti-slip ribs 44a, 44b, and 44c have the same width in the circumferential direction of the axis A. The anti-slip ribs 44d and 44e have the same width in the circumferential direction of the axis A. The width of the anti-slip ribs 44d and 44e in the circumferential direction of the axis A is larger than the width of the anti-slip ribs 44a, 44b, and 44c in the circumferential direction of the axis A. The retaining ribs 44a, 44b, 44c, 44d, and 44e have the same width in the radial direction of the axis A. As shown in FIG. 4, the width w1 of the retaining ribs 44a, 44b, 44c, 44d, and 44e in the radial direction of the axis A is in the range of 0.5 mm to 5.0 mm, and is 1.5 mm in this embodiment. As shown in FIG. 2, the band portion 44 has a plurality of through holes 44f formed over approximately half the circumference of the band portion 44. The plurality of through holes 44f are arranged in a line in the circumferential direction of the axis A.

[0033] The main body 45 includes an upper surface 46 and a side surface 48. The upper surface 46 includes an annular portion 46a that expands from the lower end of the band portion 44 in the radial direction of the axis A, and a semicircular portion 46b that extends from the outer end of the annular portion 46a in the radial direction of the axis A. The side surface 48 includes a semicylindrical portion 48a that extends downward from the outer end of the semicircular portion 46b and a narrowed portion 48b that is bent inward from the lower end of the semicylindrical portion 48a. Although not shown, the main body 45 is formed in a shape that covers at least a part of the grinding wheel GW. In this embodiment, the main body 45 is formed in a shape that covers a part of the grinding wheel GW that extends over approximately half the circumference. In the example shown in FIG. 1, the main body 45 is arranged at a position that covers the rear part of the grinding wheel GW. The main body 45 can prevent grinding powder from flying from the grinding wheel GW toward the user when the grinder 2 is used. It can also be said that the main body portion 45 covers at least a portion of the spindle 32 .

[0034] As shown in FIG. 5, the bearing box 10 is formed with a cover mounting part 50 having a substantially cylindrical shape that protrudes downward along the axial direction of the shaft A (i.e., the vertical direction). As shown in FIG. 4, the cover mounting part 50 includes a mounting groove 51, a guide groove 52, and a flange 54. The mounting groove 51 is continuously provided over the entire circumference of the cover mounting part 50. A width w2 from the bottom surface of the guide groove 52 to the bottom surface of the mounting groove 51 in the radial direction of the shaft A is within a range of −4.5 mm to 9.5 mm, and is 0.4 mm in this embodiment. When the width w2 is a positive value, the width w2 corresponds to the depth of the mounting groove 51 when the bottom surface of the guide groove 52 is taken as the reference plane. When the width w2 is a negative value, the width w2 corresponds to the depth of the guide groove 52 when the bottom surface of the mounting groove 51 is taken as the reference plane. In addition, a rubber ring 56 is attached to the mounting groove 51.

[0035] As shown in FIG. 6, the rubber ring 56 has a band shape that is substantially symmetrical with respect to the axis A. The rubber ring 56 has a lower surface 56a (see FIG. 7), an upper surface 56b, an inner cylindrical surface 56c, an outer cylindrical surface 56d, a lower inclined surface 56e, and an upper inclined surface 56f. The lower inclined surface 56e is formed by chamfering the connection portion of the lower surface 56a and the outer cylindrical surface 56d. The upper inclined surface 56f is formed by chamfering the connection portion of the upper surface 56b and the outer cylindrical surface 56d. The connection portion of the lower surface 56a and the inner cylindrical surface 56c and the connection portion of the upper surface 56b and the outer cylindrical surface 56d are not chamfered. Therefore, the connection portion of the lower surface 56a and the inner cylindrical surface 56c and the connection portion of the upper surface 56b and the outer cylindrical surface 56d have a so-called pin-angle shape. Furthermore, when no load is applied to the rubber ring 56, the inner diameter of the inner cylindrical surface 56c is slightly smaller than the outer diameter of the bottom surface of the mounting groove 51 (see FIG. 4). Therefore, the rubber ring 56 is attached to the mounting groove 51 in a state in which it is slightly pushed outward in the radial direction of the axis A by the bottom surface of the mounting groove 51. Note that FIG. 6 illustrates the rubber ring 56 in an unloaded state.

[0036] As shown in FIG. 7, the rubber ring 56 has a substantially rectangular shape in a cross section perpendicular to the circumferential direction of the axis A. The width w3 of the rubber ring 56 in the axial direction of the axis A is 0.5 mm or more, and is 5.0 mm in this embodiment. The width w4 of the rubber ring 56 in the radial direction of the axis A is within a range of 0.5 mm to 10 mm, and is 2.5 mm in this embodiment. The ratio of the width w3 of the rubber ring 56 in the axial direction of the axis A to the width w4 of the rubber ring 56 in the radial direction of the axis A is 0.05 or more, and is 2.0 in this embodiment. The ratio of the width w4 of the rubber ring 56 in the radial direction of the axis A to the width w1 of the retaining ribs 44a, 44b, 44c, 44d, and 44e in the radial direction of the axis A (see FIG. 4) is within a range of 0.1 to 20, and is 1.7 in this embodiment. Note that FIG. 7 illustrates the rubber ring 56 in an unloaded state.

[0037] 4, a part of the rubber ring 56 is fitted in the mounting groove 51, and the remaining part protrudes from the mounting groove 51 radially outward of the axis A. A lower surface 56a of the rubber ring 56 protruding from the mounting groove 51 functions as an upper wall surface of the guide groove 52.

[0038] As shown in FIG. 5, the flange 54 protrudes in the radial direction of the axis A at the bottom end of the cover mounting portion 50. The upper surface of the flange 54 functions as a lower wall surface of the guide groove 52. The flange 54 has cutouts 54a, 54b, 54c, 54d, and 54e formed therein corresponding to the retaining ribs 44a, 44b, 44c, 44d, and 44e (see FIG. 3) of the wheel cover 12. The cutouts 54a, 54b, 54c, 54d, and 54e communicate with the guide groove 52. As shown in FIG. 4, the width w5 from the bottom surface of the guide groove 52 to the outer circumferential surface of the flange 54 in the radial direction of the axis A is in the range of 0.5 mm to 5.5 mm, and is 1.7 mm in this embodiment. The width w5 corresponds to the depth of the guide groove 52 when the outer circumferential surface of the flange 54 is taken as the reference surface. Moreover, the sum of the width w2 and the width w5 corresponds to the depth of the mounting groove 51 when the outer peripheral surface of the flange 54 is taken as the reference surface.

[0039] 8, the bearing box 10 is provided with a locking mechanism 104. The locking mechanism 104 includes a locking plate 106, sleeves 108 and 110, and a compression spring 112.

[0040] The lock plate 106 has a flat base 106a extending in the left-right direction in a shape that does not interfere with the gear housing 8 and the bearing box 10, an operating portion 106b extending upward from the left end of the base 106a, long holes 106c and 106d formed in the base 106a and having a longitudinal direction in the left-right direction, an arm 106e extending forward from the right end of the base 106a, a locking portion 106f (see Figure 5) protruding toward the left near the front end of the arm 106e, and a contact portion 106g protruding upward between the long hole 106c and the long hole 106d of the base 106a.

[0041] The lock plate 106 is attached to the screw 58c arranged on the rear left side and the screw 58d arranged on the rear right side out of the screws 58a, 58b (see FIG. 5), 58c, and 58d that fix the bearing box 10 to the gear housing 8. The screw 58c extends in the vertical direction and passes through the long hole 106c of the lock plate 106 to fasten the sleeve 108, the bearing box 10, and the gear housing 8. The screw 58d extends in the vertical direction and passes through the long hole 106d of the lock plate 106 to fasten the sleeve 110, the bearing box 10, and the gear housing 8. The lock plate 106 is held by the screws 58c and 58d so as to be slidable in the left-right direction.

[0042] A spring accommodating chamber 8a that accommodates a compression spring 112 is formed between the gear housing 8 and the bearing box 10. The spring accommodating chamber 8a opens downward and receives the abutment portion 106g of the lock plate 106 therein. A spring receiving wall 8b is formed on the right side of the spring accommodating chamber 8a. The compression spring 112 is disposed in the spring accommodating chamber 8a along the left-right direction. The right end of the compression spring 112 abuts against the spring receiving wall 8b and the left end of the compression spring 112 abuts against the abutment portion 106g. The compression spring 112 biases the lock plate 106 leftward relative to the bearing box 10, i.e., in a direction that brings the engaging portion 106f (see FIG. 5) closer to the cover mounting portion 50.

[0043] As shown in FIG. 9, when attaching the wheel cover 12 to the grinder 2, the operating portion 106b (see FIG. 5) of the lock plate 106 is pushed rightward to move the locking portion 106f away from the cover mounting portion 50. From this state, the retaining ribs 44a, 44b, 44c, 44d, and 44e (see FIG. 3) of the wheel cover 12 are aligned with the notches 54a, 54b, 54c, 54d, and 54e (see FIG. 5) of the cover mounting portion 50, and the wheel cover 12 is slid upward relative to the bearing box 10 so that the cover mounting portion 50 fits inside the band portion 44. In the state shown in FIG. 9, the outer diameter of the outer cylindrical surface 56d of the rubber ring 56 is slightly larger than the inner diameter of the band portion 44. Therefore, when the wheel cover 12 is slid upward relative to the bearing box 10, the inner peripheral edge of the upper surface of the band portion 44 eventually comes into contact with the lower inclined surface 56e of the rubber ring 56. Since the lower inclined surface 56e has a shape that expands in diameter as it goes upward, a radial reaction force is generated between the band portion 44 and the rubber ring 56 when the band portion 44 comes into contact with the lower inclined surface 56e. Therefore, when the wheel cover 12 is slid further upward, the rubber ring 56 is pressed and compressed radially inward of the axis A and fits into the inside of the band portion 44. As a result, the wheel cover 12 can be attached to the bearing box 10 as shown in FIG. 10. In this state, when the pressing of the operating portion 106b (see FIG. 5) is released, the lock plate 106 is pushed back to the left by the urging force of the compression spring 112 (see FIG. 8). As a result, the tip of the locking portion 106f is pressed against the outer circumferential surface of the band portion 44. Further, a rubber ring 56 (see FIG. 9) fitted into the inner surface of the band portion 44 is pressed between the band portion 44 and the cover mounting portion 50. The rubber ring 56 seals the gap between the band portion 44 and the cover mounting portion 50.

[0044] The position of the wheel cover 12 after it is attached to the bearing box 10 when the anti-slip ribs 44a, 44b, 44c, 44d, and 44e (see FIG. 3) are aligned with the cutouts 54a, 54b, 54c, 54d, and 54e (see FIG. 5) (i.e., the position of the wheel cover 12 as shown in FIG. 10) is hereinafter also referred to as the "attachment / detachment position."

[0045] The wheel cover 12 attached to the bearing box 10 can rotate around the axis A with respect to the cover attachment portion 50. When the wheel cover 12 is rotated from the attachment / detachment position with respect to the bearing box 10, the band portion 44 slides against the rubber ring 56 (see FIG. 9), and the retaining ribs 44a, 44b, 44c, 44d, and 44e (see FIG. 3) move around the axis A within the guide groove 52 (see FIG. 9). As a result, as shown in FIG. 4, the lower surfaces of the retaining ribs 44a, 44b, 44c, 44d, and 44e face the upper surface of the flange 54. In this state, the retaining ribs 44a, 44b, 44c, 44d, and 44e come into contact with the upper surface of the flange 54, thereby preventing the wheel cover 12 from sliding downward with respect to the bearing box 10. In this case, the wheel cover 12 cannot be removed from the bearing box 10.

[0046] 10, the position of the multiple through holes 44f of the band portion 44 relative to the locking portion 106f of the lock plate 106 changes. When the locking portion 106f of the lock plate 106 is aligned with one of the multiple through holes 44f of the band portion 44, the locking portion 106f enters the through hole 44f due to the biasing force of the compression spring 112, as shown in FIG. 11, for example. In this state, the wheel cover 12 is engaged with the lock plate 106, so that the wheel cover 12 is prohibited from rotating relative to the bearing box 10 and is fixed to the bearing box 10.

[0047] The position of the wheel cover 12 with respect to the bearing box 10 in a state in which the locking portion 106f is inserted into the through-hole 44f (ie, the position of the wheel cover 12 as shown in FIG. 11) will hereinafter be referred to as a "fixed position".

[0048] The fixing position of the wheel cover 12 varies depending on the through-hole 44f aligned with the locking portion 106f. That is, the position of the main body portion 45 in the circumferential direction of the axis A varies depending on the through-hole 44f aligned with the locking portion 106f. When changing the fixing position of the wheel cover 12, the operating portion 106b (see FIG. 5) of the lock plate 106 is pushed rightward to cause the locking portion 106f to come out of the through-hole 44f, and then the wheel cover 12 is rotated relative to the bearing box 10. Then, the fixing position of the wheel cover 12 can be selected by appropriately selecting the through-hole 44f aligned with the locking portion 106f.

[0049] When removing the wheel cover 12 from the bearing box 10, the operating portion 106b (see FIG. 5) of the lock plate 106 is pressed in, and the wheel cover 12 is rotated to the attachment / detachment position relative to the bearing box 10 as shown in FIG. 10. In this state, the retaining ribs 44a, 44b, 44c, 44d, and 44e are aligned with the notches 54a, 54b, 54c, 54d, and 54e, allowing the wheel cover 12 to slide downward relative to the bearing box 10. In this case, the wheel cover 12 can be removed from the bearing box 10.

[0050] 4, the overlap width w6 between the band portion 44 and the cover mounting portion 50 in the axial direction of the shaft A is 2.5 mm or more, and is 14 mm in this embodiment. The ratio of the width w3 (see FIG. 7) of the rubber ring 56 in the axial direction of the shaft A to the overlap width w6 between the band portion 44 and the cover mounting portion 50 in the axial direction of the shaft A can be any value, but is 0.36 in this embodiment.

[0051] (Modification) The shape of the rubber ring 56 may be changed as appropriate. For example, the rubber ring 56 may not have at least one of the lower inclined surface 56e and the upper inclined surface 56f. For example, as shown in Fig. 12, the rubber ring 56 may not have the upper inclined surface 56f. Also, as shown in Fig. 13, the rubber ring 56 may have a recess 56g recessed from the inner cylindrical surface 56c toward the radially outward direction of the axis A.

[0052] An elastic member other than the rubber ring 56 may be attached to the mounting groove 51. For example, as shown in Fig. 14, instead of the rubber ring 56, a plurality of O-rings 72, 74 may be attached to the mounting groove 51 (see Fig. 4) so ​​as to be lined up vertically. Also, a plurality of elastic members (not shown) may be attached to the mounting groove 51 along the circumferential direction of the axis A. For example, a plurality of rubber members obtained by dividing one rubber ring 56 into a plurality of pieces may be attached to the mounting groove 51.

[0053] The material used for the elastic member may be other than rubber (for example, sponge, plastic resin).

[0054] The values ​​of the width w1 of the retaining ribs 44a, 44b, 44c, 44d, and 44e in the radial direction of the shaft A, the width w2 of the mounting groove 51 in the radial direction of the shaft A, the width w3 of the rubber ring 56 in the axial direction of the shaft A, the width w4 of the rubber ring 56 in the radial direction of the shaft A, the width w5 of the flange 54 in the radial direction of the shaft A, and the overlap width w6 of the band portion 44 and the cover mounting portion 50 in the axial direction of the shaft A may be changed as appropriate. Also, the ratio between any two of the values ​​of the widths w1, w2, w3, w4, w5, and w6 may be changed as appropriate.

[0055] The lower inclined surface 56e and the upper inclined surface 56f may be formed by a method or means other than chamfering. For example, the lower inclined surface 56e and the upper inclined surface 56f may be formed by a mold.

[0056] The upper wall surface of the guide groove 52 may be defined by the cover mounting portion 50 (bearing box 10) instead of the lower surface 56a of the rubber ring 56. In this case, the mounting groove 51 and the guide groove 52 may be provided at positions spaced apart from each other on the cover mounting portion 50.

[0057] The retaining ribs 44a, 44b, 44c, 44d, and 44e may not be provided on the band portion 44. Furthermore, the guide groove 52 may not be provided on the cover attachment portion 50.

[0058] (Correspondence) As described above, in one or more embodiments, the grinder 2 (example of a tool) includes the motor 14 (example of a prime mover), the bevel gear 34 (example of a power transmission mechanism) connected to the motor 14, the housing 42 that accommodates the motor 14 and the bevel gear 34, the spindle 32 (example of a tool holder) that is connected to the bevel gear 34 and holds a grinding wheel GW (example of a tool holder), the wheel cover 12 (example of a cover) including the main body 45 that covers at least a part of the spindle 32, and the band portion 44 (example of a mounting portion) having a substantially cylindrical shape along the axis A (example of a rotation axis of the tool holder), the cover mounting portion 50 (example of a mounting portion) that is fixed to the housing 42 and to which the band portion 44 is attached, and the lock mechanism 104 that switches between a state in which the band portion 44 is fixed to the cover mounting portion 50 and a state in which it is not fixed. The cover mounting portion 50 is configured to receive the band portion 44 slidably along the axis A and to receive the band portion 44 rotatably around the axis A. The cover mounting part 50 is provided with a mounting groove 51 that is aligned along the circumferential direction of the axis A. A rubber ring 56 (an example of an elastic member) is attached to the mounting groove 51 and is pressed in the radial direction of the axis A by the band part 44 and the cover mounting part 50. The ratio of a width w3 of the rubber ring 56 in the axial direction of the axis A to a width w4 of the rubber ring 56 in the radial direction is greater than 1.0.

[0059] According to the above configuration, the ratio of the width w3 of the rubber ring 56 in the axial direction to the width w4 of the rubber ring 56 in the radial direction is greater than 1.0. Therefore, the width w3 of the rubber ring 56 in the axial direction can be increased without excessively increasing the width w4 of the rubber ring 56 in the radial direction. This makes it possible to suppress the rubber ring 56 from deforming significantly in the radial direction, and to support the band portion 44 over a wide range by the rubber ring 56. Therefore, rattling of the band portion 44 relative to the cover mounting portion 50 can be sufficiently suppressed.

[0060] In one or more embodiments, the ratio of the width w3 of the rubber ring 56 in the axial direction to the overlap width w6 of the band portion 44 and the cover attachment portion 50 in the axial direction is 0.2 or greater.

[0061] The ratio of the width w3 of the rubber ring 56 in the axial direction to the overlap width w6 can be said to be an index showing the relative width of the range in which the rubber ring 56 can support the band portion 44 with respect to the overlap width w6. The larger this ratio is, the more the rubber ring 56 can support the band portion 44, so that the rattle of the band portion 44 with respect to the cover mounting portion 50 is effectively suppressed. In conventional grinders, the ratio of the width of the elastic member in the axial direction to the overlap width is less than 0.2 at most. According to the above configuration, the ratio of the width w3 of the rubber ring 56 in the axial direction to the overlap width w6 is 0.2 or more. Therefore, the rattle of the band portion 44 with respect to the cover mounting portion 50 can be effectively suppressed more than before.

[0062] In one or more embodiments, the mounting groove 51 and the rubber ring 56 are each provided continuously and uninterrupted along the circumferential direction.

[0063] According to the above configuration, the gap between the band portion 44 and the cover mounting portion 50 is sealed by the rubber ring 56. This makes it possible to prevent dust generated when the grinding wheel GW processes the workpiece from passing between the band portion 44 and the cover mounting portion 50. Furthermore, according to the above configuration, the rubber ring 56 is formed in one piece, so the number of parts of the grinder 2 can be reduced.

[0064] In one or more embodiments, the band portion 44 is provided with retaining ribs 44a, 44b, 44c, 44d, and 44e (examples of protrusions) that protrude from the band portion 44 toward the cover attachment portion 50. The cover attachment portion 50 is provided with guide grooves 52 that regulate movement of the retaining ribs 44a, 44b, 44c, 44d, and 44e in the axial direction. The ratio of the width w4 of the rubber ring 56 in the radial direction to the width w1 of the retaining ribs 44a, 44b, 44c, 44d, and 44e in the radial direction is greater than 1.0.

[0065] From the viewpoint of improving the durability of the rubber ring 56, it is desirable to increase the thickness of the rubber ring 56 (i.e., the width w4 of the rubber ring 56 in the radial direction) to a certain extent. In conventional grinders, the ratio of the width of the elastic member in the radial direction to the width of the protruding portion in the radial direction was at most about 1.0. For this reason, the thickness of the rubber ring 56 was relatively small, and the durability of the rubber ring 56 may be poor. According to the above configuration, the ratio of the width w4 of the rubber ring 56 in the radial direction to the width w1 of the retaining ribs 44a, 44b, 44c, 44d, and 44e in the radial direction is greater than 1.0, so that the thickness of the rubber ring 56 can be made relatively large. Therefore, the durability of the rubber ring 56 can be improved.

[0066] In one or more embodiments, the band portion 44 is provided with retaining ribs 44a, 44b, 44c, 44d, and 44e that protrude from the band portion 44 toward the cover attachment portion 50. The cover attachment portion 50 is provided with a guide groove 52 that restricts movement of the retaining ribs 44a, 44b, 44c, 44d, and 44e in the axial direction. An upper wall surface of the guide groove 52 (an example of a portion of the guide groove) is defined by a lower surface 56a of a rubber ring 56.

[0067] In a configuration in which the guide groove 52 restricts the axial movement of the retaining ribs 44a, 44b, 44c, 44d, and 44e, if the mounting groove 51 and the guide groove 52 are provided spaced apart in the axial direction, there is a risk that the cover mounting part 50 will become large in the axial direction. According to the above configuration, the rubber ring 56 (i.e., the mounting groove 51) and the guide groove 52 are provided adjacent to each other in the axial direction, so that the cover mounting part 50 can be made small in the axial direction.

[0068] In one or more embodiments, the rubber ring 56 includes a lower surface 56a (an example of a first surface) that is substantially perpendicular to the axial direction and faces the band portion 44 when the band portion 44 is attached to the cover attachment portion 50, an upper surface 56b (an example of a second surface) that is substantially perpendicular to the axial direction and faces the opposite side to the lower surface 56a, an outer cylindrical surface 56d (an example of a third surface) that is substantially perpendicular to the radial direction and faces the outside of the attachment groove 51, and an inner cylindrical surface 56c (an example of a fourth surface) that is substantially perpendicular to the radial direction and faces the inside of the attachment groove 51. The rubber ring 56 has a substantially rectangular shape defined by the lower surface 56a, the upper surface 56b, the outer cylindrical surface 56d, and the inner cylindrical surface 56c in a cross section perpendicular to the circumferential direction.

[0069] Between the mounting groove 51 and the band portion 44, a space (also called a placement space) for placing the rubber ring 56 is formed. In general, the placement space has a substantially rectangular shape in a cross section perpendicular to the circumferential direction. If the shape of the rubber ring 56 does not conform to the shape of the placement space (for example, if the rubber ring 56 has a substantially circular shape in a cross section perpendicular to the circumferential direction), a relatively large gap will be generated between the mounting groove 51 (or the band portion 44) and the rubber ring 56. If this gap is large, the rubber ring 56 may be significantly deformed when pressed by the band portion 44 and the cover mounting portion 50, so that rattling of the band portion 44 relative to the cover mounting portion 50 may not be suppressed. According to the above configuration, the rubber ring 56 has a substantially rectangular shape in a cross section perpendicular to the circumferential direction. That is, since the rubber ring 56 has a shape conforming to the shape of the placement space, the gap generated between the mounting groove 51 (or the band portion 44) and the rubber ring 56 can be reduced. This makes it possible to prevent the rubber ring 56 from being significantly deformed when the rubber ring 56 is pressed by the band portion 44 and the cover mounting portion 50. Therefore, rattling of the band portion 44 relative to the cover mounting portion 50 can be suppressed.

[0070] In one or more embodiments, the juncture of the lower surface 56a and the outer cylindrical surface 56d includes a lower angled surface 56e (an example of a chamfered shape).

[0071] If the connection portion between the lower surface 56a and the outer cylindrical surface 56d does not have the lower inclined surface 56e, the band portion 44 will abut vertically against the lower surface 56a during the process of attaching the band portion 44 to the cover attachment portion 50. At this time, even if the band portion 44 is pushed in the attachment direction, no force is generated to compress the rubber ring 56 in the radial direction. Therefore, the rubber ring 56 does not fit well inside the band portion 44, which may cause inconvenience to the user performing the attachment work. According to the above configuration, the connection portion between the lower surface 56a and the outer cylindrical surface 56d has the lower inclined surface 56e. During the process of attaching the band portion 44 to the cover attachment portion 50, the band portion 44 abuts against the lower inclined surface 56e. Since the lower inclined surface 56e has a shape that expands in diameter toward the attachment direction of the band portion 44, a radial reaction force is generated between the band portion 44 and the rubber ring 56 when the band portion 44 is pushed in the attachment direction. This reaction force compresses the rubber ring 56, causing it to enter inside the band portion 44. Therefore, according to the above configuration, the rubber ring 56 enters inside the band portion 44 relatively easily, reducing the inconvenience felt by the user performing the installation work.

[0072] In one or more embodiments, at least one of the juncture of the lower surface 56a and the inner cylindrical surface 56c and the juncture of the upper surface 56b and the inner cylindrical surface 56c does not have a chamfered shape.

[0073] When the band portion 44 slides against the rubber ring 56, the rubber ring 56 may be pulled by the band portion 44, causing the rubber ring 56 to fall off from the mounting groove 51. According to the above configuration, at least one of the connection portion between the lower surface 56a and the inner cylindrical surface 56c and the connection portion between the upper surface 56b and the inner cylindrical surface 56c has a so-called pin-angle shape. Even if the rubber ring 56 is pulled by the band portion 44, the pin-angle shape gets caught on the bottom surface or wall surface of the mounting groove 51, so that the rubber ring 56 is retained in the mounting groove 51. Therefore, it is possible to prevent the rubber ring 56 from falling off from the mounting groove 51. [Explanation of symbols]

[0074] 2: Grinder 4: Motor housing 6: Rear housing 8: Gear housing 8a: Spring chamber 8b: Spring support wall 10: Bearing box 12: Wheel cover 14: Motor 16: Output shaft 18: Bearings 20: Bearing 22: Power supply circuit 24: Power cord 26: Switch 28: 1st bevel gear 30: 2nd bevel gear 32: Spindle 34: Bevel gear 36: Bearing 38: Shaft lock 40: Bearing 41: Bearing 42: Housing 44: Band 44a, 44b, 44c, 44d, 44e: Anti-slip ribs 44f: Through hole 45: Main body 46:Top part 46a: Circular section 46b: Semicircular section 48: Side part 48a: Semi-cylindrical section 48b: Squeezing section 50: Cover mounting part 51: Mounting groove 52: Guide groove 54: Flange 54a, 54b, 54c, 54d, 54e: Notches 56: Rubber ring 56a: Bottom surface 56b:Top surface 56c: Inner cylindrical surface 56d: Outer cylindrical surface 56e: Lower slope 56f: Upper slope 56g : Concave 58a, 58b, 58c, 58d: Screws 72, 74: O-ring 104: Locking mechanism 106: Lock plate 106a: base 106b: Operation unit 106c, 106d: Long hole 106e: Arm 106f: Locking part 106g: Contact part 108, 110: Sleeve 112: Compression spring GW: Grinding wheel IF: Inner flange OF: Outer flange

Claims

1. The prime mover and a power transmission mechanism connected to the prime mover; a housing that accommodates the prime mover and the power transmission mechanism; a tool holder connected to the power transmission mechanism and holding a tool bit; a cover including a main body that covers at least a portion of the tool bit holder and a mounting portion that has a substantially cylindrical shape along the rotation axis of the tool bit holder; a mounting portion fixed to the housing and to which the mounting portion is attached; a locking mechanism that switches between a state in which the attachment portion is fixed to the attachment receiving portion and a state in which the attachment portion is not fixed, the mounting portion is configured to receive the mounting portion slidably along the rotation axis and to receive the mounting portion rotatably around the rotation axis, The mounting portion is provided with a mounting groove that extends along the circumferential direction of the rotating shaft, an elastic member is attached to the mounting groove and is pressed in the radial direction of the rotary shaft by the mounting portion and the mounted portion; A tool, wherein a ratio of a width of the elastic member in the axial direction of the rotation shaft to a width of the elastic member in the radial direction is greater than 1.

0.

2. The tool of claim 1 , wherein a ratio of the width of the elastic member in the axial direction to an overlap width of the mounting portion and the mounted portion in the axial direction is 0.2 or greater.

3. The tool according to claim 1 , wherein the mounting groove and the elastic member are each provided continuously and without interruption along the circumferential direction.

4. The mounting portion is provided with a protruding portion that protrudes from the mounting portion toward the mounted portion, a guide groove that restricts movement of the protruding portion in the axial direction is provided in the mounting portion; The tool of claim 1 , wherein a ratio of the width of the resilient member in the radial direction to a width of the protrusion in the radial direction is greater than 1.

0.

5. The mounting portion is provided with a protruding portion that protrudes from the mounting portion toward the mounted portion, a guide groove that restricts movement of the protruding portion in the axial direction is provided in the mounting portion; The tool of claim 1 , wherein a portion of the guide groove is defined by the resilient member.

6. The elastic member is a first surface that is substantially perpendicular to the axial direction and faces the mounting portion when the mounting portion is mounted to the mounted portion; a second surface that is substantially perpendicular to the axial direction and faces the opposite side to the first surface; a third surface that is substantially perpendicular to the radial direction and faces outward from the mounting groove; a fourth surface that is substantially perpendicular to the radial direction and faces the inside of the mounting groove, The tool according to claim 1 , wherein the elastic member has a generally rectangular shape defined by the first surface, the second surface, the third surface, and the fourth surface in a cross section perpendicular to the circumferential direction.

7. The tool of claim 6 , wherein a connecting portion of the first surface and the third surface has a chamfered shape.

8. The tool according to claim 6 , wherein at least one of a connecting portion between the first surface and the fourth surface and a connecting portion between the second surface and the fourth surface does not have a chamfered shape.

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