JP2016032844A - Electric tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric tool which reduces dust which is caused by cutting and enters into a bearing installed in a spindle cover to significantly extend the product life.SOLUTION: A grinder includes: a gear case 3 provided at the front side of a motor housing incorporating with a motor; a spindle 31 extending from the gear case in a direction substantially perpendicular to a rotary shaft of the motor; and spindle covers (41, 46) covering the spindle. The spindle covers comprise: a first cover member 41 made of a metal; and a second cover member 46 which is attached so as to cover the first cover member 41 and made of a resin. The second cover member 46 is fastened to the gear case 3 by screws so as to sandwich the first cover member 41. A wheel guard 20 is fixed by the second cover member 46.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power tool in which a spindle is attached to a gear case, and more particularly to an improved structure of a spindle cover that covers a spindle to which a tip tool is attached.

  A disk grinder is known as an example of an electric tool. The disk grinder performs operations such as polishing and grinding by rotationally driving a tip tool such as a grindstone or a diamond wheel attached to a spindle by a motor as a driving source. In a disk grinder, chips and dust generated during use enter the bearing portion, and the bearing portion may be worn or damaged during long-term use. Also in the conventional electric tool, by providing a cover (spindle cover) so as to cover the spindle, the structure prevents the dust from directly entering the bearing portion through the gap on the front side in the axial direction of the spindle. In addition, when a power grinder is a disc grinder, it is required to use a wheel guard that covers a part of the tip tool according to safety standards, and the wheel guard mounting position is changed according to the work. ing.

  FIG. 11 is a side view of a conventional disc grinder 101. A broad “housing” that constitutes the outer shell of the disc grinder 101 includes a substantially cylindrical motor housing 102 that houses a motor (not shown), a tail cover 105 that is attached to the rear of the motor housing 102, a motor A gear case 103 attached to the front of the housing 102 and a spindle cover 141 are constituted by four main parts.

  An electric motor (not shown) is accommodated in the motor housing 102 so that the rotation shaft extends in the front-rear direction. The gear case 103 accommodates a power transmission mechanism including two sets of bevel gears that convert the power transmission direction of the motor rotation shaft by about 90 degrees, and the motor rotation shaft (not shown) from the rear side. ) Extends into the gear case, the spindle 131 is arranged in a direction substantially perpendicular to the rotation axis of the motor, and the rotation axis and the spindle 131 are connected using a bevel gear (not shown) to transmit the rotational force of the motor. Is done. The gear case 103 is inserted from the front side in the axial direction to the rear side, and the opening of the gear case 103 is opened in the opening 102a on the front side of the motor housing 102 by four screws 129 arranged in parallel with the rotation shaft of the motor. The parts 103a are attached so as to correspond. On the side of the gear case 103, a handle mounting hole 139b for mounting a side handle (not shown) is formed. A spindle 131 projects downward from the gear case 103, and a grindstone 8 as a tip tool is attached to the tip (lower end) of the spindle 131. The grindstone 8 is detachably fixed to the spindle 131 by fixtures 138a and 138b, such as resinoid flexible toys, flexible toys, resinoid toys, sanding disks, etc., having a diameter of 100 mm. Surface polishing and curved surface polishing of synthetic resin, marble, concrete, etc. are possible. Moreover, concrete or stone can be cut by attaching a diamond wheel as a tip tool. The rotational speed of the tip tool is, for example, about 2000 to 4000 rpm, but the rotational speed may be appropriately set according to the work target. The wheel guard 20 is a protection member for protecting an operator from scattering of a ground member or damaged abrasive grains, and is fixed to the spindle cover 141 by a belt-like belt 21. The wheel guard 20 and the belt 21 are required to be made of metal according to the standard, and need to be configured to have sufficient strength to satisfy the standard. The wheel guard 20 can be adjusted so that the wheel guard 20 can be rotated by a predetermined angle in the circumferential direction. However, the rotation angle is limited, and the wheel guard 20 is attached to the spindle cover 141 within a range in which the tip tool does not face the operator. It is necessary to mount so that it can swing.

  The spindle cover 141 holds a bearing (described later) that supports the spindle 131 and prevents dust from entering the bearing. The spindle cover 141 has four openings 103b in the lower opening 103b of the gear case 103. It is attached with two screws (not shown). The switch operating trigger 106 that activates the rotation of the motor is provided below the grip portion 105a that is arranged to extend rearward. In this embodiment, when the operator grips the grip portion 105a, the operator can easily keep the switch-on state by moving the trigger 106 upward.

  FIG. 12 is a top view of the disc grinder 101 according to the embodiment of the present invention. The motor housing 102 and the tail cover 105 are configured by an integral structure of plastic (organic polymer resin). Although not shown, a power cord for supplying power to the motor is connected to the rear end of the tail cover 5. Here, the wheel guard 20 is a metal member disposed so as to cover the upper surface portion and the outer edge portion of the rear side of the grindstone 8 and the entire portion on the lower surface side slightly from the outer edge portion, and is linearly formed on the front side. The opening 20a to be formed is formed. The circumferentially wound belt 21 is formed such that two close end portions are bent outward in the radial direction, and screw holes (not shown) formed in these parallel adjacent bent portions 21a and 21b. The wheel guard 20 can be fixed at a predetermined position in the circumferential direction by tightening with a bolt 22a and a nut 22b. When changing the fixing position of the wheel guard 20, it is possible to fix the wheel guard 20 by rotating it by a predetermined angle in the direction of the arrow 23 by loosening the nut 22b. According to the international standards for electric tools, even if the wheel guard 20 is displaced from the position where it is fixed during work due to an impact such as loosening of the nut 22b for mounting or hitting the wheel guard 20, the operator is It is required to take some measures (installation of a stopper mechanism) so that the opening 20a of the wheel guard 20 does not face. For example, in patent document 2, the stopper (stop piece) which prevents rotation of a wheel guard is provided using the screw which fixes a gear case to a motor housing. The stop piece is formed with an abutting portion that abuts on the wheel guard at a position eccentric to the axis of the screw, and is fixed to the motor housing together with the gear case by the screw. By providing a stopper, when the opening 20a rotates approximately 90 degrees clockwise from the state shown in FIG. 12, a part of the bolt 22a or nut 22b comes into contact with the stopper, preventing further rotation of the wheel guard 20. Is done.

JP 2012-61552 A Japanese Patent No. 5544867

  FIG. 13 shows a cross-sectional structure of a conventional spindle cover. In FIG. 13, the spindle 131 is arranged so as to be orthogonal to the rotation axis (the axis is the front-rear direction in FIG. 11) of a motor (not shown). The rotational force of the motor is decelerated by the second bevel gear 132 that meshes with a bevel gear (a first bevel gear (not shown)) provided on the rotation shaft on the motor side, and the spindle 131 rotates. The upper end of the spindle 131 is pivotally supported by a metal (not shown) fixed to the gear case, and the vicinity of the approximate center is pivotally supported by a bearing 133 such as a ball bearing. The bearing 133 is press-fitted into a cylindrical fixing position inside the spindle cover 141, and an annular fixing ring 135 is provided on the upper side of the bearing 133 and is fixed by two screws 136. The spindle cover 141 is formed with a through hole 141a through which the spindle 131 passes. The through hole 141a is preferably made as small as possible with the spindle 131 so that dust or the like does not enter the bearing 133 from between them. At this time, an annular felt packing 134 is inserted below the bearing 133 in order to further prevent dust and the like from entering. On the outer peripheral side of the spindle cover 141, an attachment surface 141c is formed in which an outer shape for fixing the wheel guard 20 is formed in a cylindrical shape. A groove portion 141d extending in the circumferential direction with a reduced diameter is formed in the vicinity of the center in the vertical direction of the mounting surface 141c. A convex portion (not shown) protruding inward is formed on a part of the inner periphery side of the wheel guard 20, and this convex portion is located in the groove portion 141d so that the groove portion 141d and the convex portion are engaged with each other. The wheel guard 20 is held so as not to fall off in the axial direction (downward here).

  As described above, the structure of the spindle cover 141 is devised so that dust generated by cutting or grinding work enters from between the spindle cover 141 and the spindle 131 and the bearing 133 in the spindle cover 141 is damaged. Was. However, in order to further extend the life of the electric power tool, it has been desired to further improve the dust prevention measures for the bearing portion.

  The present invention has been made in view of the above background, and its purpose is to reduce the intrusion of dust generated by concrete cutting work into the bearing installed in the spindle cover, and greatly extend the product life. It is to provide a power tool.

The characteristics of representative ones of the inventions disclosed in the present application will be described as follows.
According to one aspect of the present invention, a motor having a rotation shaft, a motor housing that houses the motor, a gear case that houses a power transmission mechanism that transmits the rotational force of the motor and is attached to the motor housing, and a power transmission mechanism A power tool having a spindle that rotates and rotates a tip tool, and a bearing that rotatably supports the spindle, and a first cover member that has a first through hole that passes through the spindle and holds the bearing A second cover member fixed to the gear case is provided so as to cover the outer peripheral side of the first cover member. As described above, the conventional spindle cover is manufactured by dividing it into the first and second cover members, so that the bearing installed in the spindle cover can be held well and also effectively protected by an external impact or the like. can do. In addition, a wheel guard that covers a part of the outer peripheral side of the tip tool is formed, and an attachment portion (attachment surface) in which a groove portion extending in the circumferential direction is provided in the second cover member is formed. It was configured to be fixed so as to be adjustable in the circumferential direction so as to engage with the groove. With this configuration, since the optimal shape for holding the wheel guard can be realized by the second cover member, the degree of freedom in designing and manufacturing the first and second cover members is increased, and the spindle cover has good performance. Can be realized. Further, a protrusion extending in the axial direction or the radial direction of the spindle is provided in a part of the first cover member, and a penetrating portion that penetrates the protrusion is provided in the second cover member, and the protrusion is arranged in the radial direction of the spindle through the penetrating portion. It is configured to project outward and to function as a stopper that abuts when the wheel guard rotates to the limit position with respect to the gear case. As a result, a protrusion is added to the first cover member, and the protrusion of the spindle cover is protruded from the hole provided in the peripheral portion held by the wheel guard of the second cover member, so that the wheel guard is moved to a certain angle or more. It can be set as the structure which does not rotate, and it can be set as the structure which does not make a wheel guard move beyond a certain angle at the time of grinding wheel destruction.

  According to another feature of the invention, the first cover member is made of metal and the second cover member is made of resin. Therefore, the degree of freedom of the shape of the second cover member is large and the weight can be reduced. In addition, a protrusion for preventing the relative movement of the first and second cover members is provided, and the second cover member is fixed to the gear case in a state where the first cover member is sandwiched between the gear case and the second cover member. The cover member was configured to be fixed to the gear case by a screw provided in parallel with the axial direction of the spindle. Therefore, since the work process for fixing the first and second cover members hardly increases, an increase in manufacturing cost can be suppressed.

  According to another feature of the present invention, a flange portion that extends radially outward and is continuous in the circumferential direction is formed on a part of the spindle, and the flange portion is disposed closer to the tip tool than the first through hole. The second cover member covers the flange portion from the tip tool and is provided with a second through hole for penetrating the spindle. A labyrinth space is formed by the first and second through holes and the flange portion. Configured to be. By providing the labyrinth space, chips and dust mixed into the bearing portion from the tip end side of the spindle can be greatly reduced. In addition, a step portion having a large diameter in the circumferential direction is formed on the side of the second cover member in contact with the first cover member of the second through hole. Furthermore, the rotation axis of the motor and the axial direction of the spindle are arranged substantially orthogonal to each other, and the power transmission mechanism includes a first bevel gear connected to the rotation shaft of the motor and a second bevel gear connected to the spindle. Since the total length of the slight gap portion extending from the tip end side of the spindle to the bearing portion can be increased, the dust resistance of the bearing portion can be further improved.

  According to still another aspect of the present invention, a motor having a rotating shaft, a motor housing that houses the motor, a gear case that houses a power transmission mechanism that transmits the rotational force of the motor and is attached to the motor housing, and a power transmission mechanism A power tool having a spindle for rotating the tip tool, a bearing that rotatably supports the spindle, and a wheel guard that covers a part of the outer peripheral side of the tip tool, the first penetration penetrating the spindle A first cover member having a hole and holding the bearing, and a second cover member fixed to the gear case so as to cover the outer peripheral side of the first cover member are provided, and a wheel guard is provided on the second cover member. Is fixed, and a protrusion for preventing rotation of the wheel guard is provided on the first cover member. For this reason, the spindle cover portion can be formed into an optimum shape by two members divided for each function. Further, the second cover member is formed with a groove portion that is substantially continuous in the circumferential direction for fixing the wheel guard so as not to be disengaged in the axial direction of the spindle, and a through portion that penetrates the protrusion from the first cover member. The second cover member is screwed to the gear case so as to sandwich the first cover member in the axial direction of the spindle.

  According to the present invention, a resinous second cover is covered from above the metal first cover, and the first cover and the second cover are alternately arranged around the protrusion provided on the spindle circumference. By doing so, it is possible to prevent the bearing from being damaged by dust entering from the gap between the spindle cover portion and the spindle. Moreover, since the wheel guard is provided on the first cover side having high rigidity, the performance of the stopper mechanism of the wheel guard can be maintained while using the resin-made second cover member having low rigidity.

It is the elements on larger scale near the spindle of the electric tool concerning the example of the present invention. It is a disassembled perspective view for demonstrating the assembly structure of the gear case 3 and the 1st and 2nd cover members (41, 46) of the electric tool which concerns on the Example of this invention. FIG. 4 is an exploded perspective view for explaining an assembly structure of the gear case 3 and the first and second cover members (41, 46) of the electric power tool according to the embodiment of the present invention, from an angle different from FIG. FIG. In FIG. 3, it is a perspective view which shows the state which attached the packing land 41 to the gear case 3. FIG. It is a perspective view which shows the state which attached the packing land cover 46 from the state of FIG. 4 is a perspective view for showing a single shape of a motor housing 2. FIG. FIG. 3 is a perspective view for illustrating a state where a gear case 3 is attached to a motor housing 2. It is a perspective view which shows the whole shape of the housing of the electric tool which concerns on the Example of this invention. It is the elements on larger scale near the spindle of the electric tool concerning the 2nd example of the present invention. It is the elements on larger scale for demonstrating the labyrinth space in FIG. It is a side view which shows the conventional disc grinder. It is a top view which shows the conventional disc grinder. It is a fragmentary sectional view which shows the holding structure of the spindle of the conventional disc grinder.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same part in the following figures, and repeated description is abbreviate | omitted. Further, in this specification, description will be made assuming that the front, rear, left, right, and up and down directions are directions shown in the drawing.

  FIG. 1 is a partially enlarged view of the vicinity of a spindle of an electric power tool according to an embodiment of the present invention. In this embodiment, the conventional spindle cover 141 shown in FIG. 13 is manufactured not with a single component (one piece) but with two components (two pieces). That is, a member (spindle cover portion) corresponding to the spindle cover 141 is composed of two parts, a packing land 41 as a first cover member and a packing land cover 46 as a second cover member. For example, the packing land 41 is manufactured as an integral product of an aluminum alloy, and the packing land cover 46 is manufactured as a molded product of a synthetic resin such as plastic. In the conventional disc grinder 101 (see FIGS. 11 to 13), the spindle cover 141 is configured to have two functions: a function of holding a bearing and a function of a fixed base for fixing the wheel guard 20. However, in this embodiment, the packing land 41 functions to hold the bearing 33 and the packing land cover 46 functions as a fixed base of the wheel guard 20.

  The packing land 41 has a substantially cup-like shape for accommodating the bearing 33 therein, and a flange portion 41c for attachment to the gear case 3 is formed around the upper surface so that the spindle 31 penetrates in the lower center portion. Through-hole 41a is formed, and a ball-type bearing 33 for supporting the spindle 31 is accommodated on the upper side. A cylindrical felt packing 34 is inserted on the lower side of the bearing 33, and an annular, metal-made fixing ring 51 is fixed on the upper side by screws 52 at two locations in the circumferential direction. The fixing ring 51 suppresses the upper side of the outer ring of the bearing 33. A bevel gear 32 is provided on the upper side of the bearing 33. The bevel gear 32 and the bearing 33 are fixed to the spindle 31 by press-fitting. The packing land cover 46 is a second cover member that is fixed to the gear case 3 so as to cover the outer peripheral side of the packing land 41. In the present embodiment, the packing land cover 46 is manufactured by integral molding of a synthetic resin such as plastic because of weight reduction and ease of manufacture. A through hole 46 a that contacts the outer peripheral side of the lower end portion of the packing land 41 is formed below the packing land cover 46. The shape of the packing land cover 46 is optimally formed for fixing the wheel guard 20, and an attachment surface 46 c is formed on the outer peripheral portion of which the outer shape for fixing the wheel guard 20 is formed in a cylindrical shape. A groove 46d extending in the circumferential direction with a reduced diameter is formed near the center in the vertical direction of the mounting surface 46c. A convex portion (not shown) projecting inward is formed on a part of the inner peripheral side of the wheel guard 20, and the convex portion (not shown) is located in the groove 46d so that the wheel guard 20 is axially (here, the lower side). In the direction).

  2 and 3 are exploded perspective views for explaining an assembly structure of the gear case 3 and the first and second cover members (41, 46) of the electric power tool according to the embodiment of the present invention. 2 and 3 show the same components viewed from different directions, and the spindle 31 and the bevel gear 32 and the bearing 33 attached thereto are not shown. The packing land cover 46 is fixed to the gear case 3 with the packing land 41 interposed therebetween. Various fixing methods can be considered, but in this embodiment, four screws (not shown) are used for screwing. Therefore, screw seats 47a to 47d having screw holes for screwing are formed at the corners of the flat portion extending in a flange shape of the packing land cover 46, and screw holes 48a to 48d are formed near the center of each screw seat 47a. Is formed. On the other hand, the packing land 41 has an optimal shape for fixing the bearing 33 (see FIG. 1), and has a through hole 41 a having an outer diameter that is slightly larger than the outer diameter of the bearing 33. Screw bosses 44a and 44d for fixing a screw 52 (see FIG. 1) are formed at two locations on the outer periphery in the radial direction from the through hole 41a. The side of the screw bosses 44a, 44d facing the bevel gear 32 is a pedestal for attaching the fixing ring 51, while the tip tool side is a pedestal for holding the packing land cover 46. Ribs 44b, 44c, 44e, and 44f for holding the packing land cover 46 in the axial direction of the spindle 31 are formed at a plurality of locations on the outer peripheral side of the through hole 41a. Cutouts 43a to 43d are formed at the corners of the planar portion of the packing land 41 extending in a flange shape. The screw seats 47a to 47d are located in the cutout portions 43a to 43d. Therefore, the position of the A portion of the screw seats 47a to 47d of the packing land cover 46 is compared with the position of the B portion. Therefore, the packing land cover 46 can be brought into close contact with the packing land 41, and the packing land 41 rotates in the rotational direction with respect to the gear case 3. It is held stably so as not to rotate. Screw seats 36 a, 36 d, 36 f, 36 h for screwing the packing land cover 46 are formed at the corners of the opening 3 b of the gear case 3.

  Ribbed pedestals 36b, 36c, 36e, 36g, and 36i for holding the sides of the packing land 41 are formed on the sides other than the corners of the opening 3b of the gear case 3. Since both the gear case 3 and the packing land 41 are made of a metal alloy, for example, an aluminum alloy, they can be formed into a configuration in which the inside is firmly sealed by fitting them together. On the rear side of the gear case 3, four screw seats 37a to 37d (37b is not visible in the figure) are formed through which screws for fixing the motor housing 2 pass.

  Here, as can be understood from the perspective view from the direction of FIG. 3, in this embodiment, a substantially rectangular parallelepiped extending downward from the pedestal portion (in the spindle axis direction approaching the grindstone 8) at one location on the rear side of the packing land 41. A protrusion 42 is formed. When the packing land cover 46 is attached, the protrusion 42 is disposed at a position exposed to the outside from a through portion 49 that is a hole provided in a peripheral movement portion held by the wheel guard of the packing land cover 46. It is a member that serves as a stopper for limiting the rotatable range of the wheel guard 20 by contacting the convex portion 21c of the belt 21 that fixes the wheel guard 20. Further, by providing the protrusions 42, it is possible to prevent relative movement in the rotational direction when the packing land 41 and the packing land cover 46 are mounted. The through portion 49 of the packing land cover 46 is simply a cut-out portion that penetrates from the inside (lower side) to the outside (inside the groove), and a groove portion 46d that is substantially continuous in the circumferential direction is formed in contact with the through portion 49. Yes.

  FIG. 4 is a view showing a state where the packing land 41 is mounted on the gear case 3. Also here, for convenience of explanation, a state in which the spindle 31 is not attached is shown. Here, the peripheral position of the opening 3b of the gear case 3 and the peripheral position of the packing land 41 are fitted together. Actually, the spindle 31 is fixed to the packing land 41 via a bearing 33, and the upper end of the spindle 31 is pivotally supported by the gear case 3 via a metal bearing (not shown). FIG. 5 shows a state where the packing land cover 46 is mounted from this state. After aligning the packing land cover 46 and the packing land 41 with the gear case 3 in this way, screws (not shown) provided parallel to the axial direction of the spindle 31 are screwed into the screw holes 48a to 48d at four locations. Tighten. As a result of this fixing, the packing land 41 is similarly fixed firmly to the gear case 3, so that the spindle cover portion (packing land 41 and packing land cover 46) can be fixed to the gear case 3 simply by tightening the same number of screws as before. it can. As can be understood from FIG. 5, the groove portion 46 d continuous in the circumferential direction of the packing land cover 46 is cut off by the protrusion 42 at the arrow C to form a step. That is, the protrusion 42 is configured to protrude radially outward from the outer diameter of the groove 46d, and the side surface on the circumferential side of the protrusion 42 is in a positional relationship that is substantially orthogonal to the outer peripheral surface of the groove 46d. Therefore, even when the wheel guard 20 receives a certain external force and rotates in the circumferential direction, the rotation angle is limited by the protrusion 21c formed on the belt 21 coming into contact with the protrusion 42, so that the wheel guard 20 is limited. It is possible to effectively prevent the direction of 20 from turning to an undesirable state. Further, since the protrusion 42 is not formed on the resin packing land cover 46 but formed on the metal packing land 41, the protrusion 42 is sufficient in strength and can receive a large force. It works extremely effectively as a stopper mechanism for 20 rotations.

  FIG. 6 is a perspective view for showing a single shape of the motor housing 2. The motor housing 2 can be manufactured by integral molding of plastic and has a substantially cylindrical shape. Screw openings 24a to 24d are formed at four locations in the circumferential direction on the opening 2a facing the opening 3a of the gear case 3 on the front side, and screws not shown are passed through the screw seats 24a to 24d. A female thread is formed. On the rear side of the motor housing 2, an opening 2b for connecting a tail cover 5 described later is formed.

  FIG. 7 is a perspective view for illustrating a state in which the gear case 3 is attached to the motor housing 2. Again, in order to explain the shape of the housing, the screws and spindle 31 used for fixing them are not shown. What can be understood from this figure is that the outer peripheral portion of the portion to which the spindle 31 is attached is covered with a resin-made packing land cover 46, and the packing land cover 46 and the lower surface of the packing land 41 are in the same position. Making the lower surfaces the same covers most of the area exposed to the outside of the spindle cover portion, that is, the outer peripheral portion and the entire side surface of the lower surface with an elastic synthetic resin. Covering with synthetic resin has a high degree of freedom in manufacturing by molding, can be manufactured at low cost, can reduce the impact when the spindle cover hits something, and the packing land cover 46 is damaged Various advantages such as being easily exchangeable can be obtained.

  FIG. 8 is a view showing the entire housing of the electric power tool 1 with the tail cover 5 attached to the rear of the motor housing 2. The shape of the tail cover 5 on the rear side from the motor housing 2 is the same as the shape of the conventional disc grinder 101 shown in FIGS. In FIG. 9, the power cord is connected from the rear side end of the tail cover 5, but the illustration thereof is omitted.

  In this embodiment, a grinder having a gear case provided in front of a motor housing incorporating a motor, a spindle extending from the gear case in a direction substantially perpendicular to the rotation axis of the motor, and a spindle cover covering the spindle, By attaching a resin cover so as to cover the spindle cover from above, and arranging the protrusions provided on the circumference of the spindle and the resin cover alternately, dust from entering from the gap between the resin cover and the spindle can be prevented. Bearings such as ball bearings can be prevented from being damaged by dust. In addition, the spindle cover is provided with a protrusion for restricting the wheel guard from rotating more than a certain angle, and the protrusion is extended from the hole provided in the resin cover, and the stopper part of the wheel guard is provided. The material of the pedestal portion that holds the wheel guard 20 can be made of resin while ensuring sufficient strength.

  Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a partially enlarged view of the vicinity of the spindle of the electric power tool according to the second embodiment of the present invention. In the second embodiment, the shape of the packing land cover 86 as the second cover member is mainly changed, and the shape of the packing land 81 as the first cover member is changed accordingly. The most significant change here is that the opening 86a on the lower end side of the packing land cover 86 and the opening 81a (see FIG. 10) of the packing land 81 have substantially the same diameter, so that the first and second covers. The wall surfaces of the members are arranged in the axial direction of the spindle 71. Also, a so-called labyrinth space is formed by providing a flange 71c protruding radially outward on the spindle 71 and arranging the flange 71c so as to be sandwiched between the first and second cover members in the axial direction. The wheel guard 20 is fixed to the packing land cover 86, the mounting surface 86c having a cylindrical outer shape for fixing the wheel guard 20 is formed on the outer peripheral portion, and the vicinity of the vertical center of the mounting surface 86c. The configuration is the same as that of the first embodiment in that a circumferentially extending groove 86d having a reduced diameter is formed.

FIG. 10 is a partially enlarged sectional view of FIG. The packing land 81 is an integrally formed product of an aluminum alloy, and the axial length on the lower side of the bearing is shorter than that of the packing land 31 of the first embodiment, and the felt packing 77 is formed with a small thickness in the axial direction. Is done. A flange portion 71c having a shape in which a part of the spindle 71 protrudes in the radial direction is formed in the lower portion of the opening 81a of the packing land 81. The opening 86a of the packing land cover 86 is positioned in the vicinity of the flange portion 71c. In order to reduce the gap, a part of the opening of the packing land cover 86 is notched in a step shape to form a stepped portion 86b. Thus, the flange portion 71c is accommodated at a minute distance in the radially outward space formed by the step portion 86b. Here, if the diameter near the opening 81a of the spindle 71 is r,
Inner diameter of stepped portion 86b> Outer diameter of flange portion 71c> Inner diameter of opening portion 81a≈Inner diameter of opening portion 86a> Diameter r in the vicinity of opening portion 81a of spindle 71
The dimensional relationship is such that the above relationship is established, and a plurality of concave and convex gaps are provided in the portion from the arrow D to the arrow E, so that the total length of the minute intervals from the outside to the inside increases, and the flow path resistance And a non-contact seal structure that substantially blocks the flow of air from the outside to the inside. Here, since the packing land cover 86 is made of resin, the shapes of the opening 86a and the stepped portion 86b can be easily manufactured. Further, since the step portion is not formed in the metal packing land 81, it is possible to suppress an increase in processing cost. It should be noted that the step portion is formed on either side or both sides, and if a concave and convex gap is formed in a cross-sectional view with a sufficient distance in a minute interval portion from the arrow D to the arrow E, For example, the shape is not limited to the shape based on the present embodiment, and other labyrinth structures and other shapes of labyrinth spaces may be realized.

  According to the second embodiment, the first cover member (81) is covered with the resin cover member (86) and the projection (flange portion 71c) provided on the circumference of the spindle 71 is the center. By alternately arranging the spindle cover and the resin cover, the bearing 33 installed in the spindle cover portion can be protected from dust generated by a concrete cutting operation or the like. As a result, the service life of the bearing 33 is significantly increased, so that the product life can be extended.

  As mentioned above, although this invention was demonstrated based on the Example, this invention is not limited to the above-mentioned Example, A various change is possible within the range which does not deviate from the meaning. For example, in the above-described embodiment, the example of the disk grinder in which the spindle extends in a direction substantially perpendicular to the motor shaft by using two bevel gears as the power transmission mechanism has been described. However, the present invention is not limited to the disk grinder, and the spindle from the housing. As long as the electric tool has a member for exposing the spindle and guarding the spindle, the invention can be similarly applied to other electric tools. Further, in this embodiment, the protrusion that functions as a stopper is formed so as to extend from the pedestal portion of the packing land in the spindle axis direction, but the direction perpendicular to the spindle axis direction from a part of the packing land, that is, the radial direction of the spindle You may provide so that it may protrude.

DESCRIPTION OF SYMBOLS 1 Electric tool 2 Motor housing 2a, 2b Opening part 3 Gear case 3a, 3b Opening part 5 Tail cover 8 Grinding stone 20 Wheel guard 20a Opening part 21 Belt 21a, 21b Bending part 21c Convex part 22 Screw 22a Bolt 22b Nut 24a-24d Screw Seat 31 Spindle 32 (Second) bevel gear 33 Bearing 34 Felt packing 35 Bearing holder 36a, 36d, 36f, 36h Screw seat 36b, 36c, 36e, 36g, 36i Base 37a-37d Screw seat 38a, 38b Fixing tool 39a, 39b Handle mounting hole
41 Packing land (first cover member)
41a Through-hole 41b Opening 41c Flange 42 Projection 43a-43d Notch 44a, 44d Screw boss 44b, 44c, 44e, 44f Rib 46 Packing land cover (second cover member)
46a Through hole 46c Mounting surface 46d Groove portion 47a to 47d Screw seat 48a to 48d Screw hole 49 Through portion 51 Fixing ring 52 Screw 71 Spindle 71c Flange portion 77 Felt packing 81 Packing land (first cover member)
81a, 81b Opening 86 Packing land cover (second cover member)
86a Opening 86b Stepped part 86c Mounting surface 86d Groove 101 Disc grinder 102 Motor housing 102a Opening 103 Gear case 103a, 103b Opening 105 Tail cover 105a Holding part 106 Trigger 129 Screw 131 Spindle 132 Bevel gear 133 Bearing 134 Felt packing 135 Fixed ring 136 Screw 138a, 138b Fixing tool 139b Handle mounting hole 141 Spindle cover 141a Through hole 141b Opening 141c Mounting surface 141d Groove

Claims (11)

A motor having a rotating shaft;
A motor housing that houses the motor;
A gear case that houses a power transmission mechanism that transmits the rotational force of the motor and is attached to the motor housing;
A spindle that is rotated by the power transmission mechanism to rotate the tip tool;
An electric tool having a bearing that rotatably supports the spindle,
A first cover member having a first through hole for penetrating the spindle and holding the bearing;
And a second cover member fixed to the gear case so as to cover an outer peripheral side of the first cover member. A wheel guard covering a part of the outer peripheral side of the tip tool;
Forming a mounting portion provided with a groove extending in the circumferential direction in the second cover member;
The electric tool according to claim 1, wherein the wheel guard is fixed so as to be adjustable in a circumferential direction so as to engage with the groove portion in the attachment portion. Providing a part of the first cover member with a protrusion extending in the axial direction or radial direction of the spindle,
Providing a penetrating portion for penetrating the protrusion in the second cover member;
The protrusion protrudes outward in the radial direction of the spindle through the penetrating portion, and functions as a stopper that abuts when the wheel guard rotates to a limit position with respect to the gear case. 2. The electric tool according to 2.   The electric tool according to any one of claims 1 to 3, wherein the first cover member is made of metal, and the second cover member is made of resin. Providing a protrusion that prevents relative movement of the first and second cover members,
The second cover member is fixed to the gear case in a state where the first cover member is sandwiched between the gear case,
5. The electric tool according to claim 4, wherein the second cover member is fixed to the gear case by a screw provided in parallel to an axial direction of the spindle. Forming a flange portion extending radially outward in a part of the spindle;
The flange portion is disposed closer to the tip tool than the first through hole,
The second cover member covers the flange portion from the tip tool side, and is provided with a second through-hole for penetrating the spindle,
The power tool according to any one of claims 1 to 5, wherein a labyrinth space is formed by the first and second through holes and the flange portion.   On the side of the second cover member in contact with the first cover member of the second through hole, a step portion having a large diameter in the circumferential direction is formed to accommodate the flange portion. The power tool according to claim 6. The rotational axis of the motor and the axial direction of the spindle are arranged so as to be substantially orthogonal,
The said power transmission mechanism has a 1st bevel gear connected with the rotating shaft of the said motor, and a 2nd bevel gear connected with the said spindle. The electric tool described. A motor having a rotating shaft;
A motor housing that houses the motor;
A gear case that houses a power transmission mechanism that transmits the rotational force of the motor and is attached to the motor housing;
A spindle that is rotated by the power transmission mechanism to rotate the tip tool;
A bearing that rotatably supports the spindle;
An electric tool having a wheel guard covering a part of the outer peripheral side of the tip tool,
A first cover member having a first through hole for penetrating the spindle and holding the bearing;
Providing a second cover member fixed to the gear case so as to cover an outer peripheral side of the first cover member;
The power tool, wherein the wheel guard is fixed to the second cover member, and a protrusion for preventing rotation of the wheel guard is provided on the first cover member. The second cover member is formed with a groove portion that is substantially continuous in a circumferential direction to fix the wheel guard so as not to be disengaged in the axial direction of the spindle, and a through portion through which the protrusion penetrates from the first cover member. And
The power tool according to claim 9, wherein the second cover member is screwed to the gear case so as to sandwich the first cover member in the axial direction of the spindle. The power tool according to claim 10, wherein the first cover member is made of metal, and the second cover member is made of resin.

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