JP4529858B2 - Portable cutting machine - Google Patents

Description

  The present invention relates to a power tool such as a saver saw or a hammer drill having a low vibration mechanism.

  An example of a reciprocating electric tool driven by an electric motor is a saver saw. As is well known, a saver saw is a tool that reciprocally drives a reciprocating shaft (hereinafter referred to as a plunger) having a straight saw blade (hereinafter referred to as a blade) attached to the tip thereof, and cuts the blade with the blade.

Some saver saws are provided with balance weights that reciprocate in the opposite phase to the reciprocating movement of the plunger in order to suppress vibration in the plunger axis direction generated by the reciprocating plunger and blade. (For example, see Patent Document 1)
Japanese Patent No. 2860173

In the prior art, in order to reciprocate the plunger, and with a reciprocating motion conversion mechanism provided with expensive reciprocating bearing second shaft, for low vibration, reciprocating motion of the plunger and the opposite phase to the counterweight For this purpose, a reciprocating motion conversion mechanism provided with a similar reciprocating bearing is used. The reciprocating motion conversion mechanism provided with the reciprocating bearing is expensive, has a large number of parts, has difficulty in assembling, and has a problem that a new orbit shaft for the reciprocating motion of the counterweight has to be provided.

  The object of the present invention is to eliminate the drawbacks of the electric tool by the above-described conventional low-vibration technology, that is, to reduce the number of parts, simplify the structure, improve the assemblability, and provide a low-vibration technology with a long life. That is.

The object is to provide a housing incorporating a motor, a gear case connected to one end of the housing, a second shaft rotatably attached to the housing and driven to rotate by the motor, and reciprocally movable to the gear case. An electric power tool having a plunger to be attached and a motion converting means for converting the rotary motion of the second shaft into a reciprocating motion of the plunger, wherein a plurality of semicircular grooves are provided on the outer periphery of the second shaft, The spherical rigid body can be rotated in the groove of No. 1 and the counterweight is driven in the opposite phase to the reciprocating motion of the plunger, and the spherical rigid body is 180 degrees apart in the multiple grooves and on the second shaft. This is achieved by adopting a configuration of an electric tool characterized by being in a position.

  According to the present invention, it is possible to reciprocate the counterweight in the opposite phase to the reciprocating motion of the plunger with a simple structure, and the second shaft required for the reciprocating motion of the plunger is used as the reciprocating motion axis of the counterweight. Furthermore, by providing a plurality of steel balls, it becomes possible to support the counterweight at a plurality of points, thereby achieving a long life.

The present invention will be described below with reference to FIGS. 1 to 20 showing an embodiment.
(Motor part)
The electric motor 1 is built in a resin motor housing 2, and a handle 3 is connected to the rear of the motor housing 2. The handle 3 has a built-in switch 4 for controlling power supply to the electric motor 1.
(Decelerator)
In front of the motor housing 2, an inner cover 5 and a gear cover 6 made of aluminum and incorporating a power transmission means described below are provided. A drive gear 8 is formed at the tip of the motor shaft 7, a driven gear 10 is attached to a second shaft 9 provided in parallel with the motor shaft 7, and the electric motor 1 is connected via the pair of reduction gears 8, 10. The second shaft 9 is driven to rotate. An inclined shaft portion 9a having an angle of about 14 ° with respect to the axis of the driven gear 10 is formed in front of the second shaft 9, and a sub shaft 11 concentric with the axis of the driven gear 10 is attached to the tip. Yes.
(Plunger reciprocating converter)
A reciprocating plate 18 having a swinging shaft portion 18 a is attached to the inclined shaft portion 9 a of the second shaft 9 via two bearings 17. A spherical portion 18b is formed at the distal end of the swing shaft portion 18a, and the spherical portion 18b at the distal end passes through the plunger 20 and engages with the inside of the hole portion 20a so as to be able to roll with a slight gap. 9 is converted into a reciprocating motion of the plunger 20.
(Blade holder)
The blade holder 23 in front of the plunger 20 is provided with a structure in which the blade 24 can be attached and detached by a pivotable lever operation. However, the blade 27 may be fixed by a bolt. The description is omitted because it is not directly related to the present invention.
(Main body holding part)
A front cover 15 made of an insulating heat insulating elastic member having a large friction coefficient is provided on the outer side of a part of the inner cover 5, the gear cover 6 and the motor housing 2. A base 25 is secured to the tip of the gear cover 6 to stabilize the saver saw body against the material to be cut during the cutting operation.
(Plunger holding mechanism)
A bearing metal 19 is fixed inside the front of the gear cover 6, and a plunger 20 is attached through the bearing metal 19 so as to reciprocate. As shown in FIG. 12, a roller shaft 21 penetrating the plunger is rotatably attached to the plunger 20, and the roller shaft 21 is provided so as to reciprocate integrally with the plunger 20. Further, rollers 13 are attached to both ends of the roller shaft 21 so as to be rotatable. Inside the gear cover 6, raceway surfaces 6 a and 6 b having two surface widths slightly larger than the outer diameter of the roller 13 are formed, and rotation of the plunger 20 in the circumferential direction is performed via two roller shafts 21 and 13. Suppressing by the raceway surfaces 6a and 6b prevents the blade 24 from falling down.
(Counterweight reciprocating motion converter)
As shown in FIG. 2, there are two endless semicircular grooves 9b and 9c on the outer periphery of the second shaft 9, and these two grooves are provided in opposite phases. 3 and 4 are developed views of the two grooves, which are endless grooves that return to the same position when rotated 360 degrees. Further, this groove has a point X that is 90 degrees and a point Y that is −90 degrees as shown in FIGS. 3 and 4, that is, a distance at a point where the grooves are 180 degrees apart as shown in FIG. Always has L. Further, a counterweight 26 having a cylindrical hole 26 a formed so as to be rotatable with respect to the second shaft 9 is provided on the outer circumference of the cylinder of the second shaft 9. The counterweight 26 is provided with two cylindrical holes 26b and 26c penetrating through the center of the cylindrical hole 26a and perpendicular to the cylindrical hole 26a. As shown in FIG. 9, the two cylindrical holes 26b and 26c are provided symmetrically with respect to the center of the cylindrical hole 26a and have a distance L. The surfaces having the two cylindrical holes 26b and 26c are flat surfaces. Portions 26d and 26e are provided. Further, as shown in FIGS. 10 and 11, a counter subweight 27 having a two-surface width 27a that can be inserted into the two flat portions 26d and 26e is provided. The counter subweight 27 is provided with two notches 27b and 27c for restricting the rotation of the counterweight 26 and the counter subweight 27 with respect to the second shaft 9. Two cylindrical weight guides 28 that can be fitted and slid with the two notches 27b and 27c are fixedly attached by being sandwiched between the inner cover 5 and the gear cover 6, and the counterweight 26 and the counter subweight are attached. 27 has a structure that restricts rotation with respect to the second shaft 9.
A steel ball 30 that can be fitted into the semi-cylindrical grooves 9b and 9c provided on the outer periphery of the second shaft 9 and the cylindrical holes 26b and 26c of the counterweight 26 is inserted. The steel ball 30 is formed with a two-sided width 27a of the counter subweight 27. The engagement between the semicircular grooves 9b and 9c provided on the outer periphery of the second shaft 9 and the cylindrical holes 26b and 26c of the counterweight is held by the surface.
(Explanation of counterweight reciprocation)
13 to 20 illustrate the movement of each part in the actual reciprocation of the counterweight 26. FIG. 13 and 14 show a state where the plunger 20 is in the forefront and the counterweight 26 is in the rearmost position. FIGS. 15 and 16 show a state in which the second shaft rotates 90 degrees and the plunger 20 and the counterweight 26 are at the center of the reciprocating motion. 17 and 18 show a state in which the second shaft 9 is rotated 180 degrees, the plunger 20 is at the rearmost position, and the counterweight 26 is at the foremost position. 19 and 20 show a state in which the second shaft 9 is rotated 270 degrees and the plunger 20 and the counterweight 26 are at the center of the reciprocating motion. When the second shaft 9 rotates 360 degrees, the state returns to the state shown in FIGS. The two anti-phase endless semicircular grooves 9b and 9c of the second shaft 9 and the two cylindrical holes 26b and 26c of the counterweight 26 are always fitted with the steel ball 30. Therefore, in the reciprocating motion of the counterweight 26 There are always two strength points.

  As described above, the second shaft 9 necessary for the reciprocating motion of the plunger 20 can be used as the reciprocating motion axis of the counterweight 26, and the counterweight 26 can be placed in a phase opposite to the reciprocating motion of the plunger 20 with a simple structure. It is possible to reciprocate.

  Further, by providing a plurality of steel balls 30, it becomes possible to support the counterweight 26 at a plurality of points, thereby achieving a long life.

  In the above embodiment, two steel balls 30 and two cylindrical holes of the counterweight 26 are provided. However, it is also possible to configure four steel balls 30 and four cylindrical holes of the counterweight 26. It is.

The principal part cross-section side view which shows one Embodiment of the saver saw which employ | adopted the low-vibration mechanism of this invention. The side view which shows the second shaft which comprises the principal part of this invention low-vibration mechanism FIG. 2 is a development view of a groove of the second shaft shown in FIG. 2. FIG. 2 is a development view of a groove of the second shaft shown in FIG. 2. BB sectional drawing of FIG. The front view which shows the counterweight which comprises the principal part of this invention low vibration mechanism. FIG. 7 is a right side view of the counterweight shown in FIG. 6. The left view of the counterweight shown by FIG. The CC sectional view taken on the line of FIG. The front view which shows the counter subweight which comprises the principal part of this invention low vibration mechanism. FIG. 11 is a left side view of the counter subweight shown in FIG. 10. AA sectional view taken on the line AA of FIG. The partial side view explaining operation | movement of the low-vibration mechanism of this invention. The DD sectional view taken on the line of FIG. FIG. 14 is a partial side view corresponding to FIG. 13 for explaining the operation of the low vibration mechanism of the present invention. FIG. 16 is a partial cross-sectional view taken along line EE in FIG. 15. FIG. 14 is a partial side view corresponding to FIG. 13 for explaining the operation of the low vibration mechanism of the present invention. FIG. 18 is a partial cross-sectional view taken along line FF in FIG. 17. FIG. 14 is a partial side view corresponding to FIG. 13 for explaining the operation of the low vibration mechanism of the present invention. The GG partial fragmentary sectional view of FIG.

Explanation of symbols

1 is an electric motor, 2 is a motor housing, 3 is a handle, 4 is a switch, 5 is an inner cover, 6 is a gear cover, 7 is a motor shaft, 8 is a drive gear, 9 is a second shaft, 10 is a driven gear, 11 is a sub Shaft, 13 roller, 15 front cover, 17 bearing, 18 reciprocating plate, 19 bearing metal, 20 plunger, 21 roller shaft, 23 blade holder, 24 blade, 25 base, and 26 counter Weight, 27 is a counter subweight, 28 is a weight guide, and 30 is a steel ball.

Claims (2)

A housing containing a motor;
A gear case connected to one end of the housing;
A second shaft rotatably attached to the housing and driven to rotate by the motor;
A plunger attached to the gear case so as to reciprocate;
An electric power tool having a motion converting means for converting the rotational motion of the second shaft into the reciprocating motion of the plunger;
A plurality of semicircular grooves are provided on the outer periphery of the second shaft , and a spherical rigid body is rotatable in the plurality of grooves .
The counterweight is driven in the opposite phase to the reciprocating motion of the plunger as the motion trajectory ,
The electric power tool characterized in that the spherical rigid body is positioned 180 degrees apart on the second shaft in the plurality of grooves . 2. The electric tool according to claim 1, further comprising a counter subweight that covers a part of the counterweight and moves together with the counterweight to prevent the spherical rigid body from coming out of the counterweight.

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