JP2015104772A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit vibration transmission from a tip tool to a tool body.SOLUTION: A grinder 1 includes: a motor shaft 41 extending from a motor; a spindle 42 which extends in a direction intersecting with the motor shaft 41, the spindle 42 to which a grind stone wheel 90 is attached; a speed reduction mechanism disposed between the motor shaft 41 and the spindle 42; a gear case 30 which houses the spindle 42 and the speed reduction mechanism; a first bearing 51 and a second bearing 52 which are disposed in the gear case 30 and rotatably support the spindle 42; and elastic bodies 60, 70 which are disposed between the gear case 30 and the first bearing 51 and the second bearing 52.

Description

  The present invention relates to a power tool including a tip tool that is rotationally driven by a motor.

  Various power tools including a tip tool that is rotationally driven by a motor are known, such as a grinder, a sander, a polisher, and a multi-cutter.

  The power tool as described above includes a first shaft extending from the motor and a second shaft extending in a direction intersecting the first shaft, and a tip tool is mounted on the second shaft. In the following description, the first shaft extending from the motor is referred to as “motor shaft”, and the second shaft on which the tip tool is mounted is referred to as “spindle”. That is, in the power tool as described above, the motor shaft and the spindle are arranged so that their axis lines intersect each other. The rotation of the motor shaft is transmitted to the tip tool via the spindle, and the tip tool is rotationally driven.

JP 2010-269425 A

  The tip tool mounted on the spindle is driven to rotate while being pressed against the surface of a workpiece such as metal or concrete. Therefore, the vibration of the tip tool is transmitted to the tool body via the spindle, and the tool body vibrates. When the tool body vibrates, the operator's hand holding the tool body is numb, and the worker's fatigue increases.

  An object of the present invention is to suppress vibration transmission from the tip tool to the tool body.

  The power tool of the present invention is a power tool including a tip tool that is rotationally driven by a motor. The power tool of the present invention includes a first axis extending from the motor, a second axis extending in a direction intersecting the first axis, and the tip tool being mounted thereon, and the first axis and the second axis. A speed reduction mechanism interposed therebetween, a gear case accommodating at least one end of the second shaft and the speed reduction mechanism, a bearing disposed in the gear case and rotatably supporting the second shaft, the gear case and the bearing And an elastic body interposed therebetween.

  In one aspect of the present invention, the power tool is provided on the first shaft and forms the speed reduction mechanism, the second gear is provided on the second shaft and forms the speed reduction mechanism, A first bearing provided above the second gear in the axial direction of the second shaft; and a second bearing provided below the second gear in the axial direction of the second shaft. Further, the elastic bodies are respectively interposed between the gear case and the first bearing and between the gear case and the second bearing.

  In another aspect of the present invention, the elastic body is disposed on both the radially outer side and the axially outer side of the bearing.

  In another aspect of the present invention, the bearing is housed in a bearing holding portion provided in the gear case, and the elastic body is interposed between the bearing and the bearing holding portion.

  In another aspect of the present invention, the bearing holding portion is provided with a protruding portion that protrudes toward the bearing and faces the bearing via a gap.

  In another aspect of the present invention, the power tool includes a first axis extending from a rotor of the motor, a second axis extending in a direction intersecting the first axis, and the first tool being mounted thereon, and the first axis. A speed reduction mechanism interposed between the first shaft and the second shaft, at least one end of the second shaft and a gear case that houses the speed reduction mechanism, and a bearing that is disposed in the gear case and rotatably supports the second shaft. The bearing is held by an elastic body.

  In another aspect of the present invention, two or more surfaces including the outer peripheral surface of the bearing are held by the elastic body.

  In another aspect of the present invention, a restriction portion is provided in the gear case to abut against the bearing to restrict the inclination of the second shaft.

  According to the present invention, vibration transmission from the tip tool to the tool body is suppressed.

It is a side view of the partial cross section which shows the structure of the grinder to which this invention was applied. It is a partial expanded sectional view of the grinder shown by FIG. (A) is an enlarged perspective view of an elastic body, (b) is an enlarged bottom view of the elastic body, and (c) is an enlarged cross-sectional view of the elastic body. (A) is an enlarged perspective view of an elastic body, (b) is an enlarged bottom view of the elastic body, and (c) is an enlarged cross-sectional view of the elastic body. It is a partial expanded sectional view of the grinder shown by FIG.

  Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to FIGS. A grinder 1 shown in FIG. 1 is one of power tools to which the present invention is applied.

  A grinder 1 shown in FIG. 1 includes a housing 10, a handle 20 provided at one end of the housing 10, and a gear case 30 provided at the other end of the housing 10.

  The housing 10 and the handle 20 are formed of synthetic resin, and a motor (electric motor in this embodiment) 11 is accommodated in the housing 10. The handle 20 is provided with a switch 21 operated by an operator who uses the grinder 1. When the switch 21 is operated, electric power is supplied to the electric motor 11 and the electric motor 11 rotates.

  The gear case 30 is composed of an upper case 31 and a lower case 32 made of an aluminum alloy. The upper case 31 and the lower case 32 are integrated in a state where the end faces of each other are abutted. The upper case 31 is sometimes called a “gear cover”, and the lower case 32 is sometimes called a “packing land”.

  The first shaft 41 extending from the motor 11 accommodated in the housing 10 enters the inside of the gear case 30 beyond the abutting surface between the housing 10 and the gear case 30. The first shaft 41 is fixed to a rotor (not shown) of the motor 11 and rotates integrally with the rotor. In the following description, the first shaft 41 is referred to as “motor shaft 41”.

  As shown in FIG. 2, a bevel gear (bevel gear) 41 a as a first gear is attached to the tip of the motor shaft 41 protruding into the gear case 30. On the other hand, a second shaft 42 extending in a direction intersecting with the motor shaft 41 is disposed in the gear case 30. In the following description, the second shaft 42 is referred to as “spindle 42”. The spindle 42 in the present embodiment extends in a direction orthogonal to the motor shaft 41. Further, a bevel gear (bevel gear) 42 a as a second gear is mounted on the spindle 42. The bevel gear 41a provided on the motor shaft 41 and the bevel gear 42a provided on the spindle 42 are always meshed with each other. Moreover, the bevel gear 42a has a larger diameter than the bevel gear 41a. In other words, the number of teeth of the bevel gear 42a is larger than the number of teeth of the bevel gear 41a. That is, a speed reduction mechanism is constituted by the two bevel gears 41a and 42a. Therefore, the rotational speed of the electric motor 11 is reduced, and the rotational torque is amplified and transmitted to the spindle 42.

  Here, a part of the spindle 42 protrudes above the bevel gear 42a, and another part of the spindle 42 protrudes below the bevel gear 42a. Therefore, in the following description, a part of the spindle 42 protruding above the bevel gear 42a is referred to as “spindle upper part”, and another part of the spindle 42 protruding below the bevel gear 42a is referred to as “spindle”. Sometimes called “bottom”. However, such a distinction is merely a distinction for convenience of explanation.

  The spindle 42 is rotatably supported by two bearings (first bearing 51 and second bearing 52) disposed in the gear case 30. Specifically, the upper part of the spindle is rotatably supported by the first bearing 51. On the other hand, the lower part of the spindle is rotatably supported by the second bearing 52. In the present embodiment, the first bearing 51 is a needle bearing, and the second bearing 52 is a ball bearing. But the kind of the 1st bearing 51 and the 2nd bearing 52 is not specifically limited. For example, the first bearing 51 may be a ball bearing and the second bearing 52 may be a needle bearing. Further, both the first bearing 51 and the second bearing 52 may be needle bearings or ball bearings.

  The first bearing 51 that supports the upper part of the spindle is accommodated in a bearing holding portion 31 a provided in the upper case 31. On the other hand, the second bearing 52 supporting the lower part of the spindle is accommodated in a bearing holding portion 32 a provided in the lower case 32. Therefore, in the following description, the bearing holding portion 31a provided in the upper case 31 is referred to as “upper holding portion 31a”, and the bearing holding portion 32a provided in the lower case 32 is referred to as “lower holding portion 32a”. . That is, the 1st bearing 51 is accommodated in the upper holding part 31a, and the 2nd bearing 52 is accommodated in the lower holding part 32a.

  Further, an elastic body 60 is interposed between the upper holding portion 31a provided in the gear case 30 (upper case 31) and the first bearing 51 accommodated in the upper holding portion 31a. An elastic body 70 is interposed between the lower holding portion 32a provided in the gear case 30 (lower case 32) and the second bearing 52 accommodated in the lower holding portion 32a. That is, the elastic bodies 60 and 70 are interposed between the gear case 30 and the first bearing 51 and between the gear case 30 and the second bearing 52, respectively.

  The elastic body 60 interposed between the upper holding portion 31a and the first bearing 51 is a rubber bush, and has a shape shown in FIGS. Specifically, the elastic body 60 has a cylindrical shape, and one end thereof is closed. More specifically, the elastic body 60 includes a cylindrical side wall portion 61 and a ceiling portion 62 that closes one end of the side wall portion 61. On the other hand, the elastic body 70 interposed between the lower holding portion 32a and the second bearing 52 is a rubber bush, and has a shape shown in FIGS. Specifically, the elastic body 70 has a cylindrical shape, and both ends thereof are open. More specifically, the elastic body 70 includes a cylindrical side wall portion 71 and a flange portion 72 formed at one end of the side wall portion 71. The flange portion 72 extends toward the inside of the side wall portion 71. Therefore, the diameter of one opening 73 of the elastic body 70 is smaller than the diameter of the other opening 74.

  Refer to FIG. 2 again. The elastic body 60 is accommodated in the upper holding portion 31 a so that the ceiling portion 62 overlaps the upper end surface of the spindle 42. The first bearing 51 is housed inside the elastic body 60 housed in the upper holding portion 31 a, and one end (upper end) of the spindle 42 is inserted inside the first bearing 51. As a result, the side wall portion 61 of the elastic body 60 is disposed on the radially outer side of the first bearing 51, and the ceiling portion 62 of the elastic body 60 is disposed on the axially outer side (upward) of the first bearing 51. That is, the side wall portion 61 of the elastic body 60 is disposed between the outer peripheral surface of the first bearing 51 and the inner peripheral surface of the upper holding portion 31a, and between the upper surface of the first bearing 51 and the bottom surface of the upper holding portion 31a. A ceiling portion 62 of the elastic body 60 is disposed. Accordingly, the outer peripheral surface and the upper surface of the first bearing 51 are held by the elastic body 60. In other words, two or more surfaces including the outer peripheral surface of the first bearing 51 are held by the elastic body 60. The first bearing 51 is restricted from moving toward the grinding wheel 90 by the holding force of the elastic body 60. Further, the movement of the first bearing 51 toward the grinding wheel 90 is also restricted by the step of the spindle 42 in the vicinity of the bevel gear 42a.

  On the other hand, the elastic body 70 is accommodated in the lower holding portion 32a such that the flange portion 72 overlaps the bottom surface of the lower holding portion 32a. The second bearing 52 is housed inside the elastic body 70 housed in the lower holding portion 32a, and the spindle 42 passes through the second bearing 52. As a result, the side wall portion 71 of the elastic body 70 is disposed on the radially outer side of the second bearing 52, and the flange portion 72 of the elastic body 70 is disposed on the outer side (downward) in the axial direction of the second bearing 52. In other words, the side wall 71 of the elastic body 70 is disposed between the outer peripheral surface of the second bearing 52 and the inner peripheral surface of the lower holding portion 32a, and the lower surface of the second bearing 52 and the bottom surface of the lower holding portion 32a are arranged. A flange portion 72 of the elastic body 70 is disposed therebetween. Accordingly, the outer peripheral surface and the lower surface of the second bearing 52 are held by the elastic body 70. In other words, two or more surfaces including the outer peripheral surface of the second bearing 52 are held by the elastic body 70. The movement of the second bearing 52 toward the grinding wheel 90 is regulated by the stepped portion formed in the gear case 30. On the other hand, the movement of the second bearing 52 toward the first bearing 51 is restricted by the plate 34 fixed to the gear case 30 (lower case 32) by the screw 33.

  As shown in FIG. 2, the lower end of the upper holding portion 31 a is provided with an annular protrusion 31 b that protrudes radially inward, that is, toward the first bearing 51. However, a gap 80 exists between the protruding portion 31 b and the first bearing 51. That is, the protrusion 31 b partially covers the end surface of the side wall 61 of the elastic body 60. In other words, the protruding length (p) of the protruding portion 31b with respect to the inner peripheral surface of the upper holding portion 31a is shorter than the thickness (t) of the side wall portion 61 of the elastic body 60. Therefore, the width of the gap 80 corresponds to the difference (tp) between the thickness (t) of the side wall 61 of the elastic body 60 and the protrusion length (p) of the protrusion 31b.

  A grindstone wheel 90 as a tip tool is attached to the lower end of the spindle 42 protruding from the gear case 30. Specifically, a washer 91, a grindstone wheel 90, and a wheel nut 92 are inserted through the lower end of the spindle 42 in this order. The grindstone wheel 90 is sandwiched between a washer 91 and a wheel nut 92 and rotates integrally with the spindle 42. That is, the grindstone wheel 90 which is a tip tool is rotationally driven by the electric motor 11 (FIG. 1). A wheel guard 93 is provided around the grindstone wheel 90.

  As described above, the elastic bodies 60 and 70 are interposed between the bearings 51 and 52 supporting the spindle 42 and the gear case 30. That is, the bearings 51 and 52 are held by the elastic bodies 60 and 70. Therefore, when the grindstone wheel 90 attached to the spindle 42 is pressed against a workpiece (not shown), the spindle 42 may tilt. The spindle 42 may tilt as shown in FIG. 5, for example. Further, when the spindle 42 is inclined, the bearings 51 and 52 supporting the spindle 42 are also inclined in the same direction while crushing the elastic bodies 60 and 70. For example, the first bearing 51 that supports the upper end of the spindle 42 is inclined as shown in FIG. 5 while crushing the elastic body 60. However, a protrusion 31b that protrudes toward the first bearing 51 is provided at the lower end of the upper holding part 31a in which the first bearing 51 is accommodated, and the end surface of the protrusion 31b has a gap 80 therebetween. One bearing 51 is opposed. Accordingly, when the inclination angle of the first bearing 51 reaches a predetermined angle, the first bearing 51 comes into contact with the protrusion 31b, and further inclination is prevented. That is, the protruding portion 31 b functions as a restricting portion that contacts the first bearing 51 and restricts the inclination of the spindle 42.

  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, the present invention can be applied to a sander, a polisher, and a multi-cutter. Further, the motor as a power source is not limited to an electric motor, and may be an air motor, for example.

1 grinder 10 housing 11 motor (electric motor)
20 Handle 21 Switch 30 Gear case 31 Upper case 31a Bearing holding part (upper holding part)
31b Projection part 32 Lower case 32a Bearing holding part (lower holding part)
33 Screw 34 Plate 41 First shaft (motor shaft)
41a First gear (bevel gear)
42 Second axis (spindle)
42a Second gear (bevel gear)
51 Bearing (first bearing)
52 Bearing (second bearing)
DESCRIPTION OF SYMBOLS 60 Elastic body 61 Side wall part 62 Ceiling part 70 Elastic body 71 Side wall part 72 Flange part 73,74 Opening part 80 Clearance 90 Grinding wheel 91 Washer 92 Wheel nut 93 Wheel guard

Claims (8)

A power tool comprising a tip tool that is rotationally driven by a motor,
A first shaft extending from the motor;
A second axis that extends in a direction intersecting the first axis and on which the tip tool is mounted;
A speed reduction mechanism interposed between the first shaft and the second shaft;
A gear case that houses at least one end of the second shaft and the speed reduction mechanism;
A bearing disposed in the gear case and rotatably supporting the second shaft;
An elastic body interposed between the gear case and the bearing;
Having a power tool. A first gear provided on the first shaft and constituting the speed reduction mechanism;
A second gear provided on the second shaft and constituting the speed reduction mechanism;
A first bearing provided above the second gear in the axial direction of the second shaft;
A second bearing provided below the second gear in the axial direction of the second shaft;
Have
The elastic bodies are interposed between the gear case and the first bearing and between the gear case and the second bearing, respectively.
The power tool according to claim 1. The elastic body is disposed on both the radially outer side and the axially outer side of the bearing,
The power tool according to claim 1 or 2. The bearing is accommodated in a bearing holding portion provided in the gear case,
The elastic body is interposed between the bearing and the bearing holding portion,
The power tool according to any one of claims 1 to 3. The bearing holding portion is provided with a protruding portion that protrudes toward the bearing and faces the bearing via a gap.
The power tool according to claim 4. A power tool comprising a tip tool that is rotationally driven by a motor,
A first shaft extending from the rotor of the motor;
A second axis that extends in a direction intersecting the first axis and on which the tip tool is mounted;
A speed reduction mechanism interposed between the first shaft and the second shaft;
A gear case that houses at least one end of the second shaft and the speed reduction mechanism;
A bearing disposed in the gear case and rotatably supporting the second shaft;
Have
The bearing is held by an elastic body,
Power tool. Two or more surfaces including the outer peripheral surface of the bearing are held by the elastic body.
The power tool according to claim 6. In the gear case, a restricting portion that abuts on the bearing and restricts the inclination of the second shaft is provided.
The power tool according to claim 6 or 7.

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