JP2012061552A - Grinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinder to improve light weight and cost reduction of manufacturing, and improve comfortability of work pushing the upper part of a gear cover by the palm.SOLUTION: The grinder includes a motor 11, a motor housing 2 for housing the motor 11, a spindle 7 extending to approximately right to a rotation shaft, a first bearing 16 provided at one end side of the spindle 7, a second bearing 17 provided at the other end of the spindle 7, the gear cover 3 which is mounted to the motor housing 2 and holds the first bearing 16, and a packing gland 4 which is mounted to the gear cover 3 and holds the second bearing 17. The gear cover 3 and the packing gland 4 are composed of a resin member such as plastic. Furthermore, the first and the second bearings 16, 17 are fixed to the gear cover 3 or the packing gland 4 via the first and second bearing holding metal members 50, 60 which are reinforced members.

Description

  The present invention relates to a grinder used when grinding and polishing a work material, and more particularly, to a grinder that reduces the weight by devising the shape of a gear cover portion and a packing land for holding the grinder.

  As an example of a portable grinder, a disc grinder is known as described in Patent Document 1. In the disk grinder, a motor as a driving source is accommodated in a cylindrical motor housing. A power transmission mechanism including a pair of bevel gears for converting the direction of power transmission by the rotation shaft of the motor by about 90 degrees is provided in front of the motor housing, and the power transmission mechanism is accommodated in a gear cover attached to the front of the motor housing. . A set of bevel gears changes the axial direction from the rotation axis of the motor by about 90 degrees to transmit power to the spindle, thereby rotating a disk-shaped grindstone attached to the lower part of the spindle.

  The spindle is rotatably held on the gear cover by a bearing. A packing land is provided at a lower portion of the gear cover, and holds one of the bearings holding the spindle. Conventionally, a gear cover and a packing land in a disk grinder have been manufactured from a metal such as an aluminum alloy in order to ensure sufficient strength.

JP 2007-223006 A

  The gear covers and packing lands of conventional disc grinders were made of metal such as aluminum alloy because of their strength. However, if the size of the disc grinder main body and the removable grindstone were increased, the weight increased. Therefore, it becomes easy to get tired by increasing the load on the operator's hand and arm. Further, if these are made of metal, heat is easily transmitted because of high thermal conductivity, and there is a risk that the operator may feel uncomfortable in his hand. In addition, due to soaring prices of aluminum materials, it has become difficult to reduce the manufacturing costs of grinder equipment.

  The present invention has been made in view of the above background, and an object of the present invention is to provide a grinder that is reduced in weight by using the material of the gear cover and / or packing land of the grinder as a resin.

  Another object of the present invention is to provide a grinder that reduces the influence of heat transmitted to the hand and improves the comfort and reduces the burden on the hand even when the upper part of the gear cover is pressed with the palm. is there.

  Still another object of the present invention is to provide a grinder that sufficiently secures the mounting rigidity of the spindle while reducing the weight by using a gear cover and / or packing land as a resin.

  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 rotating shaft, a motor housing that houses the motor, a spindle that is rotated by the motor and extends in a direction intersecting the rotating shaft, a tip tool attached to the spindle, and one end of the spindle A first bearing provided on the side, a second bearing provided on the other end of the spindle, a gear cover attached to the motor housing and holding the first bearing, and attached to the gear cover and holding the second bearing In a grinder having a packing land, the gear cover is made of a resin member such as plastic instead of metal. The first bearing was fixed to the gear cover via a metal first bearing holding member. Also, a first hole is provided in a region where the first bearing holding member of the gear cover or the first bearing is in contact, and the first bearing holding member or a part of the first bearing is exposed to the outside air by the first hole. It was configured to touch.

  According to another aspect of the present invention, a lock member that restricts the rotation of the spindle is provided, and the lock member is configured to be held by the first bearing holding member. Further, the packing land is made of a resin member such as plastic instead of metal. The second bearing was fixed to the packing land via the second bearing holding member, and the second bearing holding member was made of metal. In addition, a second hole is provided in a region where the second bearing holding member of the packing land contacts, and a part of the second bearing holding member is in contact with the outside air through the second hole.

  According to still another aspect of the present invention, in a grinder having a motor, a motor housing for housing the motor, a spindle to which a tip tool is attached and rotated by the motor, and a spindle housing for rotatably holding the spindle by a bearing. A part or all of the spindle housing is made of resin, the bearing is held on the spindle housing via a metal reinforcing member, a hole is provided in the spindle housing, and a part of the reinforcing member is exposed to the outside air via the hole. It was configured to touch. The spindle is arranged by providing a power transmission mechanism and rotating about 90 degrees with the rotation shaft of the motor, and the spindle housing is constituted by a gear cover attached to the front side of the motor housing and a packing land attached to the gear cover.

  According to the first aspect of the present invention, since the conventional gear cover made of metal is made of resin, it is possible to reduce the weight of the grinder, and to realize a grinder that suppresses the load on the operator's hand and is hard to get tired. . Also, when pressing the upper part of the gear cover with the palm of the hand, the part that touches the hand is made of resin with low thermal conductivity, so the temperature change of the gear cover during work is small and the work on the operator's hand is reduced. A good grinder can be realized. Further, the production cost of the gear cover can be reduced compared to a gear cover made of aluminum alloy.

  According to the second aspect of the present invention, since the first bearing is fixed to the gear cover via the metal first bearing holding member, the portion of the resin gear cover that requires strength is made of metal. A gear cover that can be reinforced with a member and has sufficient rigidity can be realized.

  According to invention of Claim 3, a 1st hole is provided in the area | region where the 1st bearing holding member or 1st bearing of a gear cover contacts, and a 1st bearing holding member or a 1st bearing is defined by a 1st hole. Since a part is in contact with the outside air, the heat from the spindle and the first bearing can be effectively dissipated.

  According to the invention of claim 4, the lock member for restricting the rotation of the spindle is provided, and the lock member is held by the first bearing holding member. Therefore, the first bearing and the lock member are made the same bearing holding member. Can be secured sufficiently, and there is no need to worry about the effect of reduced rigidity due to the adoption of a resin gear cover.

  According to the invention of claim 5, since the packing land attached to the gear cover is also made of resin, it is possible to further reduce the weight of the grinder.

  According to the sixth aspect of the present invention, since the second bearing is fixed to the packing land via the metal second bearing holding member, the portion requiring strength is made of metal even if it is a resin packing land. The packing land can be reinforced with a member made of a material and has sufficient rigidity.

  According to the invention of claim 7, the second hole is provided in a region where the second bearing holding member of the packing land contacts, and a part of the second bearing holding member is in contact with the outside air by the second hole. Therefore, the heat transmitted from the spindle to the second bearing holding member can be effectively radiated.

  According to the eighth aspect of the invention, since part or all of the spindle housing is made of resin in the grinder, the grinder can be reduced in weight. In addition, since the bearing is held on the spindle housing via a metal reinforcing member, parts that require strength can be reinforced with a metal member even if they are made of resin, and a spindle housing with sufficient rigidity is realized. it can. Furthermore, since a hole is provided in the spindle housing so that a part of the reinforcing member is in contact with the outside air, heat transmitted from the spindle or the bearing to the bearing holding member can be effectively dissipated.

  According to the ninth aspect of the present invention, the spindle is arranged by rotating approximately 90 degrees with the rotating shaft of the motor, and the spindle housing is constituted by a gear cover attached to the front side of the motor housing and a packing land attached to the gear cover. Therefore, the grinder whose output shaft and spindle shaft of the motor are 90 degrees can be configured to be lightweight.

  The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

1 is a side view of a disc grinder 1 according to an embodiment of the present invention. 1 is a top view of a disk grinder 1 according to an embodiment of the present invention. It is a fragmentary sectional view of the disc grinder 1 which shows the AA cross section of FIG. It is a bottom view of the gear cover 3 of FIG. It is a top view of the packing land 4 of FIG. It is a side view of the packing land 4 of FIG. It is sectional drawing of the BB part of the packing land 4 of FIG. It is a bottom view of the packing land 4 of FIG. It is a top view of the 1st metal member 50 of FIG. It is sectional drawing of CC part of the 1st metal member 50 of FIG. It is sectional drawing of the DD section of the 1st metal member 50 of FIG. It is a top view of the 2nd metal member 60 of FIG. It is a bottom view of the 2nd metal member 60 of FIG. It is a side view of the 2nd metal member 60 of FIG. It is sectional drawing which shows the EE cross section of the 2nd metal member 60 of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same portions are denoted by the same reference numerals, and repeated description is omitted. Further, in the present specification, description will be made assuming that the front-rear direction, the up-down direction, and the left-right direction are directions shown in the drawing.

  FIG. 1 is a side view of a disc grinder 1 according to an embodiment of the present invention. The housing of the disc grinder 1 includes a cylindrical motor housing 2 that accommodates a motor to be described later, a tail cover 5 that is attached to the rear of the motor housing 2, a gear cover 3 that is attached to the front of the motor housing 2, and a packing land 4. It consists of four main parts.

  A motor, which will be described later, is accommodated in the motor housing 2. The motor is, for example, an AC motor such as a universal motor, and a brush cap 26 is provided on a part of the motor housing 2. The gear cover 3 accommodates a power transmission mechanism including two sets of bevel gears that convert the power transmission direction by the rotation shaft of the motor by about 90 degrees, and is inserted 4 from the front in the axial direction to the rear side. The screw 29 is attached so that the opening 3 a of the gear cover 3 corresponds to the opening 2 a on the front side of the motor housing 2. A handle attachment hole 39 for mounting a side handle (not shown) is formed on the side of the gear cover 3. In addition, an air window 30 for discharging cooling air is provided above the gear cover.

  A spindle 7 extends downward from the gear cover 3, and a grindstone 8 serving as a tip tool is attached to the tip portion (lower end) of the spindle 7. The grindstone 8 can be attached to and detached from the spindle 7 by fixtures 9a and 9b. The grindstone 8 is, for example, a resinoid flexible toy, flexible toy, resinoid toy, sanding disk, etc. having a diameter of 100 mm. By selecting the abrasive grains to be mounted, surface polishing and curved surface polishing of metal, synthetic resin, marble, concrete, etc. are possible. It is. The rotational speed of the grindstone 8 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 for protecting the worker from scattering of a ground member or damaged abrasive grains, and is fixed to the packing land 4 by the belt portion 21. The wheel guard 20 and the belt portion 21 are required to be made of metal according to standards.

  The packing land 4 holds a later-described bearing for holding the spindle 7, and is attached so that the opening 40 of the packing land 4 corresponds to the lower opening 3 b of the gear cover 3.

  The switch operating trigger 6 that activates the rotation of the motor is disposed below the grip portion 5a and extends rearward along the grip portion 5a. In this embodiment, when the operator grasps the grip portion 5a, the trigger 6 is moved upward, and the motor switch is turned on. When the operator releases the grip of the grip portion 5a, the trigger 6 moves downward and the motor stops. On the side of the tail cover 5, an air window 5c (intake port) for taking in outside air by a cooling fan described later is provided.

  FIG. 2 is a top view of the disc grinder 1 according to the embodiment of the present invention. The motor housing 2 is constituted by an integral structure of plastic (organic polymer resin) such as polycarbonate. The plastic may be engineer plastic or super engineering plastic. The tail cover 5 is divided into a right tail cover and a left tail cover, and the right and left tail covers are coupled by a plurality of screws (not shown). Although not shown, a power cord for supplying power to the motor is connected to the rear end of the tail cover 5.

  As the motor rotates, a cooling fan, which will be described later, rotates, sucks outside air from the wind window 5c of the tail cover 5 in the directions of arrows 27a and 27b, and the sucked air cools the motor inside the motor housing 2, Air sucked in the direction of the arrows 28a and 28b from the wind window 30 is discharged. A spindle lock 18 is provided on the front side of the wind window 30. The spindle lock 18 is a mechanism that locks the spindle 7 so as not to rotate when a tip tool such as the grindstone 8 is attached or detached. When the upper part of the spindle lock 18 is pressed, a lock pin (not shown) The spindle 7 becomes non-rotatable by protruding and fitting into a recess (not shown).

  FIG. 3 is a partial cross-sectional view of the disc grinder 1 showing the AA cross section of FIG. In the present embodiment, the motor 11 is a universal motor that operates with an alternating current. However, the present invention is not limited to this, and other types of motors such as a direct current motor and a brushless DC motor may be used. The motor 11 is disposed so as to be accommodated in the motor housing 2, and the rotation shaft 11 a of the motor 11 is disposed so as to coincide with the axial direction (front-back direction) of the cylindrical motor housing 2. The shape of the motor housing 2 is preferably a cylindrical shape or a long cylindrical shape because the strength can be increased.

  The rotating shaft 11 a of the motor 11 is rotatably held by a bearing 13 fixed to the gear cover 3 and a bearing (not shown) fixed to the rear side of the motor housing 2. A fan guide 23 and a cooling fan 12 for obtaining a rectifying effect are provided on the front side of the motor 11 of the rotating shaft 11a. The cooling fan 12 is, for example, a plastic centrifugal fan. The cooling fan 12 sucks outside air from a wind window 5c (see FIG. 2) provided in a part of the tail cover 5 to generate an air flow that passes through the motor 11, and the gear cover 3 The air is exhausted forward from the wind window 30 provided in. In addition, although it seems that the front-end part of the wind window 30 is obstruct | occluded in the cross-sectional position shown in FIG. 3, the wind window 30 opens to the front side in the right and left part of an AA cross section so that FIG.

  The rotating shaft 11a of the motor 11 is rotatably held by a ball-type bearing 13, and a first bevel gear 14 is attached to the tip of the rotating shaft 11a. The first bevel gear 14 meshes with the second bevel gear 15 attached to the spindle 7. In this embodiment, the number of teeth of the first bevel gear 14 is sufficiently smaller than the number of teeth of the second bevel gear 15, and the first bevel gear 14 and the second bevel gear 15 function as a speed reduction mechanism.

  The spindle 7 is rotatably held on the upper side by a metal 16 that is a first bearing, and the lower side is rotatably held on a bearing 17 that is a second bearing. Here, the metal 16 is fixed to the gear cover 3 side, and the bearing 17 is fixed to the packing land 4 side. Since the gear cover 3 and the packing land 4 of this embodiment are made of resin, the metal 16 is held on the gear cover 3 via the first metal member 50, and the bearing 17 is held on the packing land 4 via the second metal member 60. Is done. The first metal member 50 and the second metal member 60 are so-called holding members for the bearing means (metal 16 and bearing 17) and are reinforcing members.

  A first hole 31 is formed at the upper ends of the spindle 7 and the metal 16, and the first hole 31 communicates with the wind window 33, so that the upper ends of the spindle 7 and the metal 16 are exposed to the outside air. As a result, the heat generated in the spindle 7 and the metal 16 can be effectively dissipated into the outside air. The purpose of providing the first hole 31 is to cool the heat of the spindle 7 and the metal 16, so that a part of the spindle 7 and the metal 16 is not exposed to the outside air, but one part of the first metal member 50. The arrangement of the first holes 31 may be determined so that the part is exposed to the outside air through the wind window 33. Further, the shape of the first metal member 50 may be devised so that a part of the first metal member 50 is exposed to the outside of the gear cover 3 by some configuration.

  A part of the second metal member 60 attached to the packing land 4 is exposed to the outside air through the second hole 47. The second hole 47 is a hole substantially continuous in the circumferential direction provided by dividing it into six in the circumferential direction, and these shapes will be described later.

  FIG. 4 is a bottom view of the gear cover 3 and shows a state in which the first metal member 50, the metal 16, and the metal 19 that holds the spindle lock 18 are attached to the gear cover 3. The outer diameter of the first metal member 50 is a shape in which a large-diameter ring and a small-diameter ring are connected, and the outer rib is formed with a mounting rib 34 extending downward from above the gear cover 3. On the outside of the mounting rib 34, reinforcing ribs 34a to 34f for ensuring sufficient rigidity of the mounting rib 34 are provided.

  A plurality of holding ribs 35a to 35h for attaching the packing land 4 are formed in the lower opening of the gear cover 3, and the packing land 4 is fixed to the holding ribs 35b, 35d, 35f, and 35h by screws. Screw holes 36a to 36d are formed. The shape of the holding ribs 35a to 35h on the inner peripheral side is an arc shape in order to make good contact with the outer peripheral surface of the packing land 4. A screw boss 38 for screwing the gear cover 3 to the motor housing 2 is formed near the front of the opening 3 a behind the gear cover 3.

  Next, the detailed shape of the packing land 4 will be described with reference to FIGS. In this embodiment, the packing land 4 that has been conventionally made of a metal such as an aluminum alloy is made of an integrally molded resin. FIG. 5 is a top view of the packing land 4. An opening 42 for penetrating the spindle 7 is formed below the center of the packing land 4. Since the bearing 17 (see FIG. 3) is disposed around the opening 42, a cylindrical accommodating portion 41 that holds the outer peripheral side of the bearing 17 is formed. An opening 40 having a larger inner diameter is formed on the upper side of the accommodating portion 41.

  Screw holes 44 for fastening the bearing retainer 25 (see FIG. 3) with screws (not shown) are formed at two locations in the circumferential direction between the opening 40 and the opening 42. A flange 45 for fixing the packing land 4 to the gear cover 3 is formed on the outer peripheral side of the cylindrical portion 43 that forms the opening 40. The flange 45 has a shape protruding from the cylindrical portion 43 to the outer peripheral side so as to form a substantially square shape when viewed from above in order to form four screw holes 45a. In part of the flange 45, a plurality of cut-through portions 45b are formed for weight reduction.

  FIG. 6 is a side view of the packing land 4. In the cylindrical portion 46 forming the accommodating portion 41, a concave portion 46b is formed between the outer diameter portions 46a. The belt portion 21 of the wheel guard 20 is fixed to the cylindrical portion 46, and the concave portion 46b is formed in a cross section in accordance with the shape of the inner peripheral side of the belt portion 21 (the cross section is convex). When the belt portion 21 is slightly loosened (see FIG. 2), the belt portion 21 is allowed to move (rotate) in the circumferential direction, but is not allowed to move in the axial direction (vertical direction). On the lower side of the flange 45 and around the screw hole 45a, a flat portion 45c having a reduced axial thickness is formed.

  FIG. 7 is a side view of the BB part of the packing land 4 of FIG. The opening 42 is large enough to allow the spindle 7 to pass therethrough, and a second hole 47 is formed between the opening 42 and the wall of the housing 41. The second hole 47 is a hole formed so as to penetrate the second metal member 60 in the axial direction so as to come into contact with the outside air, and is divided into six in the circumferential direction. In addition, in order to increase the contact area to the outside air of a 2nd metal member, the thin part 42a which made thickness thin is formed in the upper end side of the opening part 42. As shown in FIG.

  FIG. 8 is a bottom view of the packing land 4. It will be understood that the second hole 47 is formed in most of the circumferential direction in this figure. Further, a flat portion 45c formed in a flat surface for fixing the screw is formed around the screw hole 45a of the flange 45.

  As described above, the gear cover 3 and the packing land 4 are made of resin, but may be engineer plastic or super engineering plastic. As the engineer plastic, polyamide, polyacetal, polycarbonate or the like can be used. Further, as the super engineering plastic, polyphenylene sulfide, polytetrafluoroethylene, polysulfone, polyethersulfone, or the like can be used.

  Next, the shape of the first metal member 50 will be described with reference to FIGS. FIG. 9 is a top view of the first metal member 50. The first metal member 50 has a shape in which a large-diameter ring and a small-diameter ring are connected, and has a large-diameter through hole 51 through which the spindle 7 penetrates and a small-diameter through hole 52 through which the spindle lock 18 penetrates. Is formed. The first metal member 50 is preferably, for example, an iron-based metal because it has sufficient strength and can be manufactured at low cost. However, an aluminum alloy may be used from the viewpoint of weight reduction and heat dissipation.

  10 is a cross-sectional view taken along the line CC of FIG. The first metal member 50 can be formed by integrally molding metal, and is formed so that its thickness (thickness in the axial direction of the spindle 7) is uniform. 11 is a cross-sectional view taken along a line DD in FIG.

  Next, the shape of the second metal member 60 will be described with reference to FIGS. FIG. 12 is a top view of the second metal member 60. The second metal member 60 is a reinforcing member for holding the outer ring of the ball-type bearing 17 (see FIG. 3), and a cylindrical portion 61 having a diameter substantially equal to the outer diameter of the bearing 17 is formed on the upper side. . Further, a through hole 62 having a diameter slightly larger than the inner ring of the bearing 17 is formed on the lower side. FIG. 13 is a top view of the second metal member 60. The second metal member 60 is preferably, for example, an iron-based metal, and is preferably configured so that the thermal expansion coefficient is substantially the same as that of the bearing 17. FIG. 14 is a side view of the second metal member 60. The second metal member 60 may be firmly fixed by bonding to the packing land 4, or the outer ring of the bearing 17 may not be idled with respect to the packing land 4 even if it is press-fitted or simply placed.

  FIG. 15 is a cross-sectional view of the second metal member 60. The second metal member 60 has a substantially uniform thickness, has a stepped portion 63 formed in the lower part on the inner peripheral side, and is configured so that the bearing 17 does not move downward. The ring-shaped lower surface 64 of the second metal member 60 is configured such that a part of the ring-shaped lower surface 64 comes into contact with the outside air through the second hole 47, and heat generated from the bearing 17 is transmitted through the second metal member 60. Heat can be effectively dissipated.

  As described above, according to the present embodiment, since the gear cover and the packing land are formed of non-metallic lightweight members, the weight of the grinder can be reduced, and the load on the operator's arm can be suppressed. It has the effect of making it difficult to get tired. Even if an operator works by pressing the upper part of the gear cover with the palm of the hand, the gear cover is made of a resin with low thermal conductivity, so the temperature change is small, the burden on the hand is small, and comfort is greatly improved. . Furthermore, the resinization of the gear cover and the packing land can greatly reduce the manufacturing cost compared to a metal such as an aluminum alloy.

  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, although the present embodiment has been described using a disc grinder as an example of a grinder, the present invention can be similarly applied to grinders of other shapes and types. In the above-described embodiment, both the gear cover 3 and the packing land 4 are made of resin, but only one of them may be made of resin. Furthermore, in the above-described embodiment, the member that holds the spindle 7 is configured by the gear cover 3 and the packing land 4, but the spindle 7 may be configured to be held by one member.

DESCRIPTION OF SYMBOLS 1 Disc grinder 2 Motor housing 2a Opening part 3 Gear cover 3a, 3b (Gear cover) opening part 4 Packing land 5 Tail cover 5a Grasping part 5c Wind window 6 Trigger 7 Spindle 8 Grinding wheel 9a, 9b Fixing tool 11 Motor 11a (Motor rotation) Shaft 12 Cooling fan 13 Bearing 14 First bevel gear 15 Second bevel gear 16 Metal (first bearing)
17 Bearing (second bearing) 18 Spindle lock 19 Metal 20 Wheel guard 21 Belt portion 22 Tightening bolt 23 Fan guide 25 Bearing holder 26 Brush cap 29 Screw 30 Wind window 31 First hole 33 (First) wind window 34 Mounting rib 34a Reinforcing ribs 35a to 35h Retaining ribs 36a to 36d Screw holes 37a to 37h Guide ribs 38 Screw bosses 39 Handle mounting holes 40 Opening portions 41 Receiving portions 42 Opening portions 42a Thin portions 43 Cylindrical portions 44 Screw holes 45 Flange 45a Screw holes 45b Part 45c Flat part 46 Cylindrical part 46a Outer diameter part 46b Recessed part 47 Second hole 50 First metal member 51, 52 Through hole 60 Second metal member 61 Cylindrical part 62 Through hole 63 Step part 64 (of second metal member) Bottom

Claims (9)

A motor having a rotating shaft;
A motor housing that houses the motor;
A spindle rotated by the motor and extending in a direction intersecting the rotation axis;
A tip tool attached to the spindle;
A first bearing provided on one end of the spindle;
A second bearing provided on the other end of the spindle;
A gear cover attached to the motor housing and holding the first bearing;
A grinder having a packing land attached to the gear cover and holding the second bearing,
A grinder characterized in that the gear cover is made of resin. Fixing the first bearing to the gear cover via a first bearing holding member;
The grinder according to claim 1, wherein the first bearing holding member is made of metal. A first hole is provided in a region where the first bearing holding member or the first bearing of the gear cover contacts,
The grinder according to claim 1 or 2, wherein a part of the first bearing holding member is in contact with outside air by the first hole. A locking member for limiting rotation of the spindle is provided;
The grinder according to any one of claims 1 to 3, wherein the lock member is held by the first bearing holding member.   The grinder according to any one of claims 1 to 4, wherein the packing land is made of a resin. Fixing the second bearing to the packing land via a second bearing holding member;
The grinder according to claim 5, wherein the second bearing holding member is made of metal. A second hole is provided in a region where the second bearing holding member contacts the packing land,
The grinder according to claim 5 or 6, wherein a part of the second bearing holding member is in contact with the outside air by the second hole. A motor,
A motor housing that houses the motor;
A spindle to which a tip tool is attached and rotated by the motor;
In a grinder having a spindle housing for rotatably holding the spindle by a bearing,
A part or all of the spindle housing is made of resin,
The bearing is held by the spindle housing via a metal reinforcing member;
A grinder characterized in that a hole is provided in the spindle housing, and a part of the reinforcing member is in contact with outside air through the hole. The spindle is arranged by rotating approximately 90 degrees with the rotation shaft of the motor,
The grinder according to claim 8, wherein the spindle housing includes a gear cover attached to the front side of the motor housing and a packing land attached to the gear cover.

Images