JP5765017B2 - Dust collecting cover and disc grinder with dust collecting cover - Google Patents

Description

  The present invention relates to a portable disc grinder used for surface grinding work of a work material and a dust collecting cover that is attached to the grinder and collects dust such as grinding powder generated during grinding work.

  A portable disk grinder equipped with a disk-shaped (wheel-shaped) tip tool is often used for a surface grinding operation for flatly grinding the surface of a work material such as concrete or stone.

  The disc grinder includes a cylindrical case that houses a drive source such as an electric motor or an air motor, and a cylindrical boss portion is provided on the tip side of the case so as to be orthogonal to the axial direction of the case. . A spindle serving as an output shaft of the disc grinder projects from the boss portion, and a tip tool is attached to the tip of the spindle. The spindle is connected to a drive source via a gear mechanism, and when the drive source is activated, the tip tool is rotationally driven by the drive source together with the spindle.

  The disc grinder is provided with a dust collection cover, also called a dust collection adapter, in order to prevent scattering of dust such as grinding powder generated during grinding operation.

  The dust collection cover is formed in a bottomed cylindrical shape (cup shape) including a cylindrical peripheral wall that covers the outer periphery of the tip tool and a top wall that covers the back side of the tip tool, and is provided on the top wall. The mounting portion is detachably mounted on the boss portion of the disc grinder. The dust collection cover is provided with a suction duct, and this suction duct is connected to the dust collector by a flexible hose such as rubber. Thereby, the dust generated at the time of grinding work is collected by the dust collector through the suction duct and the hose without being scattered from the dust collection cover to the outside (see, for example, Patent Document 1).

  On the other hand, as a dust collecting cover, a self dust collecting type has been developed in which the dust collecting cover itself has a dust collecting function without using a dust collecting device. The dust collection cover of the self-dust collection type has a volute case part in which a centrifugal fan is rotatably accommodated. The centrifugal fan is fixed to the spindle between the tip tool and the boss part and rotates together with the tip tool. It has a structure. A suction port is provided in the partition wall facing the tip tool of the volute case, and when the centrifugal fan rotates and generates suction, dust inside the cover body is sucked into the volute case from this suction port, and the volute Dust is collected in a dust collection bag attached to the discharge duct through the flow path.

JP 2009-23005 A

  However, in the conventional dust collection cover of the self-dust collection type, the suction port provided in the volute case part opens at a predetermined size toward the tip tool, so that relatively small pieces of concrete or the like crushed during the grinding operation can be obtained. There was a possibility that a large foreign object could enter the inside of the volute case from the suction port. When foreign matter enters the inside of the volute case, the foreign matter prevents the centrifugal fan from rotating.

  An object of the present invention is to prevent foreign matters such as crushed concrete pieces from entering the centrifugal fan side from the tip tool side, and to improve the operation reliability of the dust collecting cover.

A dust collection cover according to the present invention is a dust collection cover attached to a portable disc grinder capable of attaching a tip tool to a spindle, the attachment portion being attachable to the disc grinder, and the side opposite to the attachment portion A cover main body that is formed in a bottomed cylindrical shape that opens to the outer periphery of the tip tool, is attached to the spindle between the tip tool and the attachment portion, and is accommodated in the cover main body, A partition wall provided between the tip tool and the centrifugal fan and having a suction port radially inward, and a foreign object intruding from the tip tool side to the centrifugal fan side provided at the suction port And a guide portion that protrudes from the surface of the partition wall on the tip tool side and extends to the suction port along the outer surface of the partition wall .

The dust collecting cover of the present invention is characterized in that the mesh portion includes a plurality of ribs extending continuously from the guide portion and projecting radially inward of the suction port .

In the dust collecting cover of the present invention, the outer peripheral edge of the partition wall is connected to the cover body, and the guide portion and the rib extend from the outer peripheral edge side of the partition wall in the rotation direction of the centrifugal fan, respectively. It is formed in a shape that bends toward the axis of the main body, and is arranged at equal intervals in the circumferential direction.

  The dust collecting cover of the present invention is characterized in that the number of ribs is different from the number of blades of the centrifugal fan.

  The dust collection cover according to the present invention is characterized in that the mesh portion further includes a ring body for connecting the inner peripheral ends of the ribs to each other.

  The dust collection cover according to the present invention is characterized in that the mesh portion is constituted by a lattice member.

  The dust collecting cover of the present invention is characterized in that the mesh portion is constituted by a plate-like member having a plurality of through holes.

In the dust collecting cover of the present invention, the cover main body has a volute flow path that is continuous with the discharge port, and a volute case portion that houses the centrifugal fan therein, and the suction port is coaxial with the centrifugal fan. It arrange | positions and it is opening toward the said front tool side, It is characterized by the above-mentioned.

  A disc grinder according to the present invention includes a housing that houses an electric motor, a spindle that extends from the housing and is fitted with a tip tool, a mounted portion that is disposed around the spindle, and a mounting portion that is attached to the mounted portion. The dust collection cover covering the tip tool is provided.

  According to the present invention, since the mesh portion is provided between the tip tool and the centrifugal fan, relatively large foreign matters such as concrete pieces crushed during the grinding operation enter the centrifugal fan side by the mesh portion. Can be prevented. Thereby, it can prevent that rotation of a centrifugal fan is prevented by a foreign material, and can improve the operation reliability of this dust collection cover.

  According to the present invention, since the mesh portion is constituted by a plurality of ribs, the mesh portion can be simplified and the cost of the dust collecting fan can be reduced.

  According to the present invention, the ribs are formed in a shape that extends in the rotation direction of the centrifugal fan and bends toward the axis of the cover main body, and these ribs are arranged at equal intervals in the circumferential direction. Thus, the centrifugal fan and the rotating flow in the same direction as the rotation direction can be generated to increase the efficiency of the centrifugal fan. Thereby, the dust collection efficiency of a dust collection cover can be improved, without enlarging a centrifugal fan.

  According to the present invention, since the number of ribs is made different from the number of blades of the centrifugal fan, the phase of pressure fluctuation generated between each blade of the centrifugal fan and the rib is shifted from each other, and Noise can be reduced.

  According to the present invention, since the tips on the inner peripheral sides of the plurality of ribs are connected to each other by the ring body, the strength of the mesh portion formed by the ribs can be increased. Thereby, the operation reliability of this dust collection cover is further improved.

  According to the present invention, since the mesh portion is configured by the lattice member, the mesh portion can be configured simply and firmly.

  According to the present invention, since the mesh portion is configured by the plate-like member having a plurality of through holes, the mesh portion can be easily and firmly configured.

  According to the present invention, since the net-like portion is provided at the suction port of the volute case portion that accommodates the centrifugal fan, even if the suction force of the centrifugal fan is increased by using the volute case portion, foreign matter is not generated from the suction port. It can suppress entering.

It is a partially cutaway sectional view of a disk grinder which is one embodiment of the present invention. It is sectional drawing which shows the structure of the dust collecting cover shown in FIG. It is a bottom view which shows the inside of the dust collecting cover shown in FIG. It is a perspective view of the dust collecting cover shown in FIG. It is explanatory drawing which compares and shows the angle with respect to the circumferential direction of the leaf | plate spring shown in FIG. 2, and a guide piece. It is sectional drawing which follows the AA line shown in FIG. It is a modification of the dust collecting cover shown in FIG. 3, Comprising: It is a bottom view which shows the case where a mesh part is comprised with the grid | lattice-like member. FIG. 4 is a bottom view showing a modification of the dust collecting cover shown in FIG. 3, in which a net-like part is constituted by a plate-like member having a plurality of circular holes.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  A portable (hand-held) disc grinder 11 shown in FIG. 1 is also called a disc sander, and is used for a surface grinding operation in which the surface of a work material 12 such as concrete or stone is ground flat.

  The disc grinder 11 includes a main body case 13 formed in a cylindrical shape, and an electric motor 14 is accommodated in the main body case 13. The electric motor 14 is connected to a commercial power source (not shown) via a power cord 15 drawn from the rear end of the main body case 13 and is operated by electric power supplied from the commercial power source.

  A gear case 16 is attached to the front end portion of the main body case 13, and the main body case 13 and the gear case 16 constitute a housing of the disc grinder 11.

  The gear case 16 includes a cylindrical boss portion 16 a orthogonal to the axial direction of the main body case 13, and a spindle 17 is provided on the gear case 16 so as to be rotatably supported by the boss portion 16 a. The spindle 17 is disposed coaxially with the boss portion 16 a, and a tip portion of the spindle 17 protrudes from the boss portion 16 a toward the outside of the gear case 16. A pair of bevel gears 18 a and 18 b are accommodated in the gear case 16, and the rotation of the electric motor 14 is transmitted to the spindle 17 by changing the direction of 90 degrees by these bevel gears 18 a and 18 b.

  A diamond grinding wheel 19 as a disk-shaped (wheel-shaped) tip tool is attached to the tip of the spindle 17.

  The diamond wheel 19 includes a substrate 19a formed in a cup shape from a steel plate, and a plurality of diamond wheels 19b arranged in a plane are fixed to the surface of the substrate 19a by means such as adhesion. . The diamond grindstone wheel 19 is attached to the tip of the spindle 17 at the axis of the substrate 19a, and is fixed by being sandwiched between a washer 21 attached to the spindle 17 and a nut 22 screwed to the tip of the spindle 17. Has been. Further, the diamond grinding wheel 19 can be removed from the spindle 17 by removing the nut 22.

  When a power switch (not shown) provided on the main body case 13 is turned on, electric power is supplied to the electric motor 14, and the diamond grindstone wheel 19 is driven by the electric motor 14 and rotates together with the spindle 17. By uniformly pressing the entire surface of the rotated diamond grinding wheel 19 against the surface of the work material 12 and moving it back and forth and right and left, a surface grinding operation for grinding the surface of the work material 12 flatly can be performed.

  In this embodiment, the diamond grindstone wheel 19 is used as a disk-shaped tip tool. However, the present invention is not limited to this, and the work material is pressed by pressing the entire surface against the surface of the work material 12. Other tip tools such as a sanding disk may be used as long as the tool can grind the surface of 12 in a flat manner.

  A dust collecting cover 31 is detachably attached to the disc grinder 11 in order to prevent dust such as grinding powder generated by the grinding operation from scattering. The dust collection cover 31 is also called a dust collection adapter, and is a self-dust collection type in which dust is forcibly sucked by a centrifugal fan 32 and collected in a dust collection bag 33 having a filter function.

  The dust collecting cover 31 includes a cover main body 34 formed of a resin material such as nylon. The cover main body 34 is formed in a cylindrical shape with a bottom that opens at one end on the side of the diamond grindstone wheel 19, and a case-shaped portion defined by the top wall 34 a and the partition wall 34 b is a volute case portion 35. When the dust collecting cover 31 is attached to the disc grinder 11, the volute case portion 35 is disposed between the disc grinder 11 and the diamond grinding wheel 19.

  As shown in FIG. 2, the volute case portion 35 is not shown in the figure, and is combined with the first case half 35 a and the second case half 35 b formed in a cup shape in the axial direction so that the opening ends thereof are butted. It is comprised by mutually fastening by fastening means, such as a volt | bolt. That is, the volute case part 35 can be divided in the axial direction.

  Inside the volute case part 35, a fan accommodating chamber 36 is provided as a cylindrical space, and a volute channel 37 is provided on the outer peripheral side of the fan accommodating chamber 36. The volute channel 37 is formed in a shape in which the radial dimension and the axial dimension gradually increase in the circumferential direction, that is, the passage area gradually increases. The downstream end of the volute channel 37 is connected to a discharge duct 38 as a discharge port provided on the outer periphery of the volute case portion 35. The discharge duct 38 is formed in a cylindrical shape projecting in the tangential direction of the volute case portion 35, and a flexible hose 41 such as rubber is connected to the tip of the discharge duct 38. A dust collecting bag 33 is attached.

  An attachment portion 42 is provided on the top wall 34 a of the cover body 34 in order to fix the cover body 34 to a boss portion 16 a as an attachment portion disposed around the spindle 17 of the disc grinder 11. The dust collecting cover 31 is attached to the disc grinder 11 by attaching the attachment portion 42 to the boss portion 16a.

  The centrifugal fan (dust collecting fan) 32 is housed in a fan housing chamber 36 provided inside the volute case 35.

  The centrifugal fan 32 is formed of a resin material, and is a sirocco fan in which 15 forward blades 32a whose both ends in the radial direction are curved toward the front side in the rotational direction are arranged radially on the circular substrate 32b. Yes. A mounting hole 32c that is chamfered is provided in the axial center of the centrifugal fan 32. As shown in FIG. 1, the centrifugal fan 32 is a spindle between the diamond grinding wheel 19 and the mounting portion 42 in the mounting hole 32c. 17 can be attached.

  Each blade 32a of the centrifugal fan 32 is formed in a shape in which an end surface facing a side opposite to the substrate 32b in a predetermined range on the front end side thereof is inclined so that a height dimension from the substrate 32b becomes lower toward the front end side. . Thereby, the passage cross-sectional area between the adjacent blades 32a is set to be almost constant, the pressure fluctuation of the air passing between the blades 32a of the centrifugal fan 32 during rotation is reduced, and the noise of the centrifugal fan 32 is reduced. Can be made.

  The cover body 34 is integrally provided with a cylindrical cover portion 51 extending in the axial direction from the partition wall 34b. The cover 51 is formed with a diameter larger than that of the diamond grindstone wheel 19 and is arranged coaxially with the fan housing chamber 36. When the cover body 34 is fixed to the boss portion 16 a, the tip of the spindle 17 penetrating the volute case portion 35 protrudes into the cover portion 51, and the diamond grindstone wheel 19 attached to the tip of the spindle 17 is inside the cover portion 51. Placed in. That is, the cover portion 51 covers the entire outer periphery of the diamond grindstone wheel 19 attached to the spindle 17.

  A circular through hole 52 through which the spindle 17 is inserted coaxially with the fan housing chamber 36 is provided in an inner portion of the mounting portion 42 of the top wall 34 a of the volute case portion 35. Further, a suction port 53 is provided in the partition wall 34b facing the side opposite to the boss portion 16a of the volute case portion 35, that is, the diamond grinding wheel 19 side. The suction port 53 is formed in a circular shape coaxially with the fan housing chamber 36, opens toward the diamond grinding wheel 19, and communicates the inside of the volute case part 35 with the inside of the cover part 51.

  In order to close the gap formed between the tip of the cover part 51 and the surface of the work material 12 when the diamond wheel 19 contacts the surface of the work material 12, a skirt is provided at the tip part of the cover part 51. (Seal member) 54 is provided.

  The skirt 54 is formed in a cylindrical shape having a smaller diameter than that of the cover portion 51, and is disposed in a state where the tip of the skirt 54 protrudes inside the cover portion 51. In the illustrated case, the skirt 54 is made of felt, but may be formed of other members such as a brush or a sponge.

  An annular holding piece (felt holder) 55 made of resin is fixed to the upper end of the skirt 54, and five leaf springs 56 are arranged between the holding piece 55 and the partition wall 34b. The skirt 54 is movable in the axial direction inside the cover portion 51 together with the holding piece 55, and is urged in the axial direction toward the opening side of the cover portion 51 by a leaf spring 56.

  When the surface of the diamond wheel 19 is pressed against the surface of the work material 12 during the grinding operation, the tip of the skirt 54 comes into sliding contact with the surface of the work material 12. Thereby, the gap between the tip of the cover part 51 and the surface of the work material 12 is closed by the skirt 54. Even when the dust collecting cover 31 is inclined with respect to the surface of the work material 12 during the grinding operation, the skirt 54 is formed on the work material 12 by elastically deforming the leaf spring 56 in accordance with the inclination. Can follow the surface. Thereby, it is possible to prevent the dust generated by the grinding operation from leaking to the outside of the cover part 51 from between the front end of the cover part 51 and the surface of the work material 12.

  As shown in FIGS. 4 and 5, twelve guide pieces 61 are integrally provided on the inner peripheral surface of the holding piece 55. Each of these guide pieces 61 is formed in a rib shape projecting radially inward from the inner peripheral surface of the holding piece 55, extends in the circumferential direction along the inner peripheral surface of the holding piece 55, and is centrifuged. The direction of rotation of the fan 32 is gradually inclined from the opening side of the cover portion 51 toward the partition wall 34b. That is, each guide piece 61 extends in the rotational direction of the diamond grinding wheel 19 and is inclined with respect to the circumferential direction (a plane perpendicular to the axial direction) so as to approach the suction port 53. The height of the guide piece 61 protruding inward in the radial direction from the inner peripheral surface of the cover portion 51 is uniform from one end to the other end, and all the twelve guide pieces 61 have the same shape. It has become. Furthermore, the guide pieces 61 are arranged at equal intervals in the circumferential direction, and the adjacent guide pieces 61 are arranged so as to be shifted in the circumferential direction so as not to overlap each other when viewed in the axial direction (the axial direction of the spindle 17). . Accordingly, the holding piece 55 integrally provided with the guide piece 61 can be easily formed by using a pair of injection molds that are divided in the axial direction. As a result, the manufacturing cost of the holding piece 55, that is, the dust collecting cover 31, can be reduced.

  On the other hand, the leaf springs 56 are arranged along the inner circumference of the cover portion 51 and arranged at equal intervals in the circumferential direction. One end in the longitudinal direction is fixed to the partition wall 34 b and the other end abuts on the holding piece 55. ing. That is, the leaf spring 56 is inclined in the same direction as the guide piece 61 with respect to the circumferential direction so as to extend toward the rotation direction of the diamond grinding wheel 19 and to approach the suction port 53. The protruding height of the leaf spring 56 from the inner peripheral surface of the cover portion 51 toward the radially inner side is larger than the protruding height of the guide piece 61.

  As shown in FIG. 5, the inclination angle A of each leaf spring 56 with respect to the plane perpendicular to the axial direction is set larger than the inclination angle B of the guide piece 61 with respect to the plane perpendicular to the axial direction. The inclination angle A of the leaf spring 56 does not become smaller than the inclination angle B of each guide piece 61 even if the holding piece 55 moves toward the stroke end toward the partition wall 34b while elastically deforming the leaf spring 56. It is set.

  As shown in FIGS. 3 and 4, on the surface side of the partition wall 34 b of the cover body 34, a plurality of ribs 62 are provided at equal intervals in the circumferential direction around the axis of the spindle 17. In the illustrated case, the cover main body 34 is provided with twelve ribs 62 that are smaller than fifteen blades 32 a of the centrifugal fan 32.

  Each of the ribs 62 is formed in an arc shape that extends from the outer peripheral edge portion connected to the cover portion 51 of the partition wall 34 b in the rotation direction of the centrifugal fan 32 and gradually bends toward the axis of the cover portion 51. ing. That is, each rib 62 is arranged such that the inner peripheral end is shifted to the front side in the rotational direction of the centrifugal fan 32 with respect to the outer peripheral end, and the longitudinal intermediate portion is rotated by the centrifugal fan 32. It is formed in a shape protruding toward the front side in the direction.

  Each of the ribs 62 is formed integrally with the partition wall 34b, protrudes from the outer surface of the partition wall 34b and extends along the outer surface, and extends radially from the inner peripheral edge of the partition wall 34b (suction port 53) to the suction port 53. It protrudes. The inner peripheral ends of the ribs 62 protruding from the suction ports 53 are connected to ring bodies 63 arranged coaxially with the centrifugal fan 32, respectively. The ring body 63 is formed in a cylindrical shape, and the ribs 62 are integrally connected to the outer peripheral portion thereof, whereby the tips of the ribs 62 are connected to each other.

  A portion of each rib 62 protruding from the inner peripheral edge of the partition wall 34 b to the suction port 53 and the ring body 63 constitute a mesh portion, that is, a mesh portion 71 in the suction port 53. As described above, the mesh portion 71 is configured using the ribs 62 that are provided on the cover main body 34 and have a rectifying function for guiding the swirling flow of dust. Thereby, the mesh part 71 can be made into a simple structure, and the cost of this dust collecting cover 31 can be reduced.

  In addition, since the inner peripheral ends of the plurality of ribs 62 are connected to each other by the ring body 63, the strength of the mesh portion 71 formed by the ribs 62 is increased, and the durability and operation of the dust collecting cover 31 are increased. Reliability can be further increased.

  Since the mesh portion 71 covers about half of the outer peripheral side of the suction port 53, relatively large foreign matters such as concrete pieces generated by crushing the work material 12 during grinding work are sucked toward the suction port 53 unexpectedly. Even if this is done, this foreign matter can be captured by the mesh portion 71 and prevented from entering the centrifugal fan 32 side, that is, the inside of the volute case portion 35 from the diamond grinding wheel 19 side.

  The inner peripheral portion of the suction port 53 that is not covered by the mesh portion 71 faces the substrate 19a of the diamond grindstone wheel 19, and the substrate 19a is configured to suppress entry of foreign matter.

  The cross-sectional shape of the portion provided along the outer surface of the partition wall 34b of each rib 62 is rectangular. On the other hand, as shown in FIG. 6, the cross-sectional shape of the portion of each rib 62 that protrudes from the suction port 53 that forms the mesh portion 71 faces the centrifugal fan 32 and is rearward in the rotational direction of the centrifugal fan 32. The side corners are rounded. Thereby, the flow can be smoothly guided by the rib 62 toward the axial direction of the centrifugal fan 32 while maintaining the swirling flow flowing from the diamond grinding wheel 19 side toward the centrifugal fan 32 side. Therefore, the centrifugal fan 32 increases the suction efficiency.

  When the attachment portion 42 is fixed to the boss portion 16a and the dust collecting cover 31 is attached to the disc grinder 11, the entire outer periphery of the diamond grinding wheel 19 is covered by the cover portion 51, and the grinding surface of the diamond grinding wheel 19 The back side which is the opposite side is covered with a volute case part 35. When the dust collecting cover 31 is attached to the disc grinder 11, the spindle 17 penetrating the through hole 52 of the volute case portion 35 is inserted into the attachment hole 32 c of the centrifugal fan 32, and the centrifugal fan 32 is connected to the diamond grinding wheel 19. It is fixed to the spindle 17 between the mounting portion 42 (boss portion 16a).

  When the electric motor 14 is operated in a state where the dust collecting cover 31 is mounted on the disc grinder 11, the centrifugal fan 32 rotates with the diamond grinding wheel 19 and generates a suction force at the suction port 53 of the volute case unit 35. When the diamond grinding wheel 19 is pressed against the work material 12 such as concrete or tile and grinding is performed, dust such as grinding powder is discharged from the outer periphery of the diamond grinding wheel 19, and this dust is externally applied by the skirt 54. Is prevented from flowing out to the inside of the cover portion 51. The dust retained inside the cover portion 51 is sucked into the volute case portion 35 from the suction port 53 by the suction force of the centrifugal fan 32, is discharged from the discharge duct 38 through the volute passage 37, and is collected. 33 collects dust.

  Here, the dust generated by grinding by the diamond grinding wheel 19 is discharged in a tangential direction from the outer peripheral portion of the diamond grinding wheel 19, and the outer peripheral portion of the diamond grinding wheel 19 while turning inside the cover portion 51. The air is sucked toward the suction port 53 through the holding piece 55.

  At this time, since the guide piece 61 is provided along the flow of the dust and inclined with respect to the circumferential direction on the inner peripheral surface of the holding piece 55, the dust flows along the guide piece 61, It is guided by the guide piece 61 and flows in the axial direction toward the suction port 53 while turning in the same direction as the diamond grinding wheel 19. That is, the dust flows spirally inside the cover portion 51.

  Further, the flow of dust that has passed between the outer peripheral portion of the diamond grinding wheel 19 and the holding piece 55 passes through the leaf spring 56. Since the leaf spring 56 is also provided along the flow of dust and inclined with respect to the circumferential direction, the dust flows along the leaf spring 56 and is guided by the leaf spring 56 to rotate the centrifugal fan 32. It will also flow in the axial direction toward the suction port 53 while strengthening the swirl flow directed in the direction.

  Even if the skirt 54 moves up and down following the unevenness of the work material 12, the inclination angle A of the leaf spring 56 does not become smaller than the inclination angle B of the guide piece 61. By doing so, the swirl flow of dust is not weakened.

  The dust swirl flow strengthened by the guide piece 61 and the leaf spring 56 then flows along the rib 62 and is guided to the suction port 53. Since these ribs 62 extend along the rotation direction of the centrifugal fan 32 and are bent toward the axial center of the centrifugal fan 32, the flow of dust is centrifugally enhanced by the ribs 62 while further enhancing the swirl flow. Guided toward the center of the fan 32. Further, the flow of dust flowing from the suction port 53 to the volute case part 35 is guided by the ring body 63 that connects the tips of the ribs 62 and is directed in the axial direction (inflow direction) of the centrifugal fan 32. Since the guide pieces 61, the leaf springs 56, and the ribs 62 are arranged at equal intervals in the circumferential direction, the dust flows into the volute case part 35 from the suction port 53 with a substantially uniform flow in the circumferential direction.

  The dust flowing into the volute case 35 from the suction port 53 is discharged radially outward through the blades 32 a by the rotational force of the centrifugal fan 32, and from the discharge duct 38 through the volute channel 37. It is discharged and collected in the dust collecting bag 33.

  As described above, in the dust collecting cover 31, the flow of the dust discharged from the diamond grinding wheel 19 is the same as the rotation direction of the centrifugal fan 32 by the guide piece 61, the leaf spring 56 and the rib 62 provided on the holding piece 55. Since it is made to flow in the inside of the volute case part 35, turning in the direction, the efficiency of the centrifugal fan 32 can be improved. Therefore, without increasing the size of the centrifugal fan 32, the dust collection efficiency of the dust collection cover 31 can be increased, and the dust discharged from the diamond grinding wheel 19 can be collected more efficiently.

  Further, since the number of ribs 62 is made different from the number of blades 32a of the centrifugal fan 32, the pressure fluctuation generated between each blade 32a of the centrifugal fan 32 and each rib 62 is mutually different for each blade 32a. The phase will shift. Therefore, the noise due to pressure fluctuation can be prevented from resonating, and the noise of the dust collecting cover 31 can be reduced.

  On the other hand, in the dust collecting cover 31, the suction port 53 is provided with the mesh portion 71 by the rib 62 and the ring body 63, so that relatively large foreign matters such as concrete pieces crushed during the grinding operation are unexpectedly generated. Even if it enters the inside of the cover part 51, it is possible to prevent the foreign matter from being caught by the mesh part 71 and entering the inside of the volute case part 35 from the suction port 53. Accordingly, it is possible to prevent the centrifugal fan 32 from being prevented from rotating or being damaged by foreign matters generated by crushing the work material 12 during the grinding operation, and the operation reliability of the dust collecting cover 31 is prevented. Can increase the sex.

  FIG. 7 is a bottom view showing a modification of the dust collecting cover shown in FIG. 3 and showing a case where the net-like portion is formed of a lattice-like member.

  In the case shown in FIG. 3, the rib 62 provided on the partition wall 34b is projected to the suction port 53 in order to guide the swirling flow of the dust, so that the mesh portion 71 is configured. However, in the case shown in FIG. In addition to the ribs 62 provided on the partition wall 34b, the mesh portion 71 is configured by the lattice member 81.

  The lattice member 81 has a structure in which a bar 81c assembled in a lattice is provided between an outer ring body 81a and an inner ring body 81b coaxial with the suction port 53, respectively. By configuring the mesh portion 71 using such a lattice-like member 81, the mesh portion 71 can be easily and firmly configured.

  In this case, the lattice member 81 may be formed of a resin material integrally with the cover main body 34, and the lattice member 81 is formed separately from the cover main body 34 by a material such as resin or metal, This may be configured to be attached to the suction port 53.

  FIG. 8 is a bottom view showing a modification of the dust collecting cover shown in FIG. 3, in which the net-like portion is constituted by a plate-like member having circular holes as a plurality of through holes.

  In the case shown in FIG. 3, the rib 62 provided on the partition wall 34b is projected to the suction port 53 in order to guide the swirling flow of the dust, and the net-like portion 71 is configured. However, in the case shown in FIG. In addition to the ribs 62 provided in the partition wall 34b, the net-like portion 71 is configured by a plate-like member 91 having a plurality of circular holes 91a.

  The plate-like member 91 is formed in an annular shape, and has twelve circular holes 91a arranged at equal intervals in the circumferential direction. By configuring the net-like portion 71 using such a plate-like member 91, the net-like portion 71 can be made simple and strong.

  In this case, the plate-like member 91 may be formed of a resin material integrally with the cover main body 34, or the plate-like member 91 is formed separately from the cover main body 34 by a material such as resin or metal, This may be configured to be attached to the suction port 53.

  In FIGS. 7 and 8, members corresponding to those described above are denoted by the same reference numerals.

  It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, in the above-described embodiment, the disk grinder 11 of the present invention is exemplified by an electric motor as a drive source. However, the present invention is not limited to this, and other drive sources such as an air motor and an engine are provided. The present invention may be applied to a disc grinder.

  In the above embodiment, the present invention is applied to the dust collecting cover 31 having a configuration in which the centrifugal fan 32 is accommodated in the volute case portion 35 provided in the cover main body 34. As long as the centrifugal fan 32 is accommodated in 34, the present invention may be applied to the dust collecting cover 31 that does not include the volute case part 35. In this case, a mesh portion 71 is provided between the tip tool of the cover body 34 and the centrifugal fan 32.

  Furthermore, in the said embodiment, although the case where the plate-shaped member 91 provided with the rib 62, the lattice-shaped member 81, and the circular hole 91a is used as the mesh-shaped part 71, it is not restricted to this, For example, a wire mesh, You may make it use the net-like part 71 of other shapes, such as a net | network.

  Furthermore, in the said embodiment, although the circular hole 91a is provided in the plate-shaped member 91 as a through-hole, you may make it provide not only this but the through-hole of shapes other than circular.

DESCRIPTION OF SYMBOLS 11 Disc grinder 12 Work material 13 Main body case 14 Electric motor 15 Power cord 16 Gear case 16a Boss part (attachment part)
17 Spindle 18a, 18b Bevel gear 19 Diamond wheel (tip tool)
19a Substrate 19b Diamond grinding wheel 21 Washer 22 Nut 31 Dust collection cover 32 Centrifugal fan 32a Blade 32b Substrate 32c Mounting hole 33 Dust collection back 34 Cover body 34a Top wall 34b Partition 35 Volute case part 35a First case half 35b Second case half Body 36 Fan housing chamber 37 Volute flow path 38 Exhaust duct (exhaust port)
41 Hose 42 Mounting portion 51 Cover portion 52 Through hole 53 Suction port 54 Skirt 55 Holding piece 56 Leaf spring 61 Guide piece 62 Rib 63 Ring body 71 Net-like portion 81 Grid-like member 81a Outer ring body 81b Inner ring body 81c Bar material 91 Plate -Shaped member 91a Circular hole A, B Inclination angle

Claims (9)

A dust collecting cover attached to a portable disc grinder capable of attaching a tip tool to a spindle,
A mounting portion attachable to the disc grinder;
A cover body that is formed in a cylindrical shape with a bottom that opens to the opposite side of the mounting portion and covers the outer periphery of the tip tool;
A centrifugal fan that is attached to the spindle between the tip tool and the attachment portion and is housed in the cover body;
A partition wall provided between the tip tool and the centrifugal fan , and having a suction port radially inside;
A net-like portion that is provided at the suction port and suppresses intrusion of foreign matter from the tip tool side to the centrifugal fan side ; and
A guide portion protruding from the surface of the partition wall on the tip tool side and extending to the suction port along the outer surface of the partition wall;
A dust collecting cover characterized by comprising: The dust collection cover according to claim 1, wherein the mesh portion includes a plurality of ribs that extend continuously from the guide portion and project radially inward of the suction port . An outer peripheral edge of the partition wall is connected to the cover body,
The guide portions and the ribs are formed in a shape that extends from the outer peripheral edge side of the partition wall in the rotation direction of the centrifugal fan and bends toward the axis of the cover body, and are arranged at equal intervals in the circumferential direction. The dust collection cover according to claim 2, wherein the dust collection cover is provided.   The dust collecting cover according to claim 3, wherein the number of ribs is different from the number of blades of the centrifugal fan.   The dust collection cover according to any one of claims 2 to 4, wherein the net-like portion further includes a ring body that couples the inner peripheral ends of the ribs to each other.   The dust collection cover according to claim 1, wherein the mesh portion is configured by a lattice member.   The dust collection cover according to claim 1, wherein the mesh portion is configured by a plate-like member having a plurality of through holes. The cover main body has a volute flow path connected to the discharge port, and a volute case portion that houses the centrifugal fan therein,
The dust collection cover according to any one of claims 1 to 7, wherein the suction port is disposed coaxially with the centrifugal fan and opens toward the tip tool . A housing that houses an electric motor;
A spindle extending from the housing and fitted with a tip tool;
A mounted portion arranged around the spindle;
A dust grinder according to any one of claims 1 to 8, which is attached to the attached portion and covers the tip tool.

Images