JP2012176469A - Cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a portable cutting machine with reduced noise and vibration that moves along a top surface of a material for cutting, in order to solve the following problem: when a normal inner-rotor type motor is used as a drive source, the motor is rotated at high speed to obtain high output and decelerated by a speed reduction device to secure proper rotation speed of a rotary blade, while noise and vibration are generated due to the high-speed rotation of the motor.SOLUTION: An outer-rotor type electric motor 11 is used as a drive source, to achieve a direct drive system by directly attaching a rotary blade 12 to an output shaft 11d. The electric motor 11 is rotated at a rotation speed suitable to the rotary blade 12, for example 6,000 rpm, thereby reducing the noise and vibration of the cutting machine 1.

Description

  The present invention relates to a cutting tool using a so-called outer rotor type electric motor as a drive source.

Techniques related to cutting tools using an inner rotor type brushless motor as a drive source are disclosed in the following patent documents. The inner rotor type brushless motor has a rotor (rotor) configured to include a permanent magnet (magnet) including N poles and S poles on the inner side of the motor, and a stator including three-phase stator windings. Have on the outside.
In contrast to the inner rotor type brushless motor, the outer rotor type brushless motor has a rotor (rotor) configured to include a permanent magnet (magnet) including N and S poles on the outside of the motor. A stator having stator windings is provided inside the motor.
When the outer rotor type brushless motor and the inner rotor type brushless motor are compared with the same size of the motor including the rotor and the stator, the surface area of the magnet attached to the outer rotor is larger than the inner rotor. The outer rotor type brushless motor can take a larger torque.
For this reason, it is possible to reduce the size of the outer rotor type brushless motor compared to the inner rotor type without increasing the torque (while maintaining the same torque), or when the size is not reduced but is equivalent. Can achieve a low rotation and high torque compared to the inner rotor type.

JP 2011-20205 A

While higher power of cutting tools is required in the market, conventional cutting tools produce output by using high-rotation and low-torque motors, and by using a reduction mechanism, blade rotation and torque suitable for cutting It was adjusted to become.
However, there is a problem that wind noise and vibration of the motor itself are increased by increasing the rotation speed of the motor.
The present invention is equipped with an outer rotor type brushless motor that can be set to low rotation and high torque while maintaining the output and size of the motor as compared with the inner rotor type brushless motor. The purpose is to achieve both sound and vibration reduction.

The above problems are solved by the following invention.
1st invention is equipped with the base contact | abutted to a cutting material, and the tool main body supported by the upper part of this base, and the tool main body is equipped with the outer rotor type electric motor as a drive source which rotates a rotary blade tool. It is.
According to the first invention, since the outer rotor type electric motor is provided as the drive source, the electric motor is maintained while maintaining its output and size as compared with the case where the inner rotor type brushless motor is used as the drive source. The motor can be rotated at a low speed and increased in torque, whereby both motor power up and reduction of wind noise and vibration of the motor itself can be achieved.
A second invention is a direct drive type cutting tool according to the first invention, wherein the rotary blade is directly attached to the output shaft of the electric motor.
According to the second invention, since the rotary blade is directly attached to the output shaft of the electric motor by the direct drive method, the rotational speed of the rotary blade matches the rotational speed of the electric motor. For this reason, since the rotation speed of the electric motor matches the appropriate rotation speed of the rotary blade, it can be rotated at a low speed of, for example, about 5,000 to 6,000 rotations per minute, thereby mainly cooling the electric motor. It is possible to reduce the noise or vibration of the fan's wind noise, and it is possible to reduce the noise and vibration of the cutting tool.
A third invention is a cutting tool according to the second invention, wherein the rotational speed of the electric motor is set to 5,000 to 6,000 revolutions per minute when the diameter of the rotary blade is 185 mm to 190 mm.
According to the third aspect of the invention, the electric motor can be rotated at a low speed by the direct drive method, and thereby the cutting tool can be reduced in noise and vibration can be reduced.
According to a fourth aspect of the present invention, in the first aspect of the invention, there is provided a cutting tool provided with an axial displacement mechanism for displacing a spindle attached with a rotary blade toward the base side with respect to the output shaft of the electric motor.
According to the fourth invention, since the rotation center of the rotary blade is set at a lower position on the base side by the shaft displacement mechanism, a large cutting depth of the rotary blade relative to the cutting material can be ensured.
In a fifth aspect based on the fourth aspect, the ratio α (Rm / Rc) between the rotational speed Rm of the electric motor and the rotational speed Rc of the rotary blade is set to α = 0.5˜ A cutting tool set to 2.0.
According to the fifth invention, when the appropriate rotational speed Rc of the rotary blade is, for example, approximately 6,000 revolutions per minute, the rotational speed Rm of the electric motor is approximately 3,000-12,000 revolutions per minute. be able to. Conventionally, when an electric motor is used as a drive source for an electric tool, the outer rotor type electric motor is used in the fifth aspect of the invention in consideration of the fact that it is normal to rotate the motor at a high speed of about 25,000 revolutions per minute. Since it is sufficient to rotate at an extremely low speed of about 3,000 to 12,000 revolutions per minute, the cutting noise of the cooling fan of the electric motor can be reduced to reduce the noise of the cutting tool.
A sixth invention is a cutting tool according to the fourth or fifth invention, wherein the rotational speed Rm of the electric motor and the rotational speed Rc of the rotary blade are set equal by the shaft displacement mechanism. According to the sixth invention, it is possible to reduce the noise and reduce the vibration of the cutting tool by rotating the electric motor at a low speed similarly to the direct drive while securing a large cutting depth with respect to the cutting material of the rotary blade. it can.

1 is an overall front view of a cutting tool according to an embodiment of the present invention. 1 is an overall plan view of a cutting tool according to an embodiment of the present invention. It is the (III)-(III) arrow directional view of FIG. 1, Comprising: It is a longitudinal cross-sectional view of the cutting tool which concerns on embodiment of this invention. It is the whole rear view which looked at the cutting tool which concerns on embodiment of this invention from the arrow (IV) direction in FIG. It is a figure which shows 2nd Embodiment of this invention, and is a longitudinal cross-sectional view of the cutting tool provided with the gear meshing type axial displacement mechanism. It is a figure which shows 3rd Embodiment of this invention, and is a longitudinal cross-sectional view of the cutting tool provided with the belt displacement type shaft displacement mechanism.

Next, an embodiment of the present invention will be described with reference to FIGS. 1-3 has shown the cutting tool 1 of this embodiment. The cutting tool 1 is a so-called portable marnoko, and includes a flat plate-like base 2 that is brought into contact with the upper surface of the cutting material W, and a tool body 10 supported on the upper portion of the base 2.
The tool body 10 includes an electric motor 11 as a drive source and a circular rotary blade 12 attached directly to the output shaft 11d of the electric motor 11. The lower side of the rotary blade 12 is protruded from the lower surface of the base 2, and the protruding portion is cut into the cutting material W to be cut. In each figure, the rotary blade 12 is cut into the cutting material by moving the cutting tool 1 in the cutting progress direction indicated by the white arrow. In the following description, with respect to the longitudinal direction of the member or configuration, the cutting progress direction is defined as the front side or the front portion, and the opposite side is defined as the rear side or the rear portion. However, regarding the electric motor 11, the rotating blade 12 side is the front side or the front part in the motor axis J direction, and the opposite side is the back side or the rear part.
As shown in FIG. 3, the electric motor 11 is a brushless motor, which is a so-called outer rotor type electric motor. The electric motor 11 includes a rotor 11c that is rotatably supported on the outer peripheral side of a stator 11b fixed in a motor case 11a. An output shaft 11d is attached to the rotor 11c. The output shaft 11d is rotatably supported via bearings 11f and 11g. The rear side bearing 11f is attached to the rear part of the motor case 11a, and the front side bearing 11g is attached to a motor mounting base part 14b provided on the back side of the blade case 14.
A cooling fan 11e for cooling the motor is attached to the rear portion of the output shaft 11d. A number of exhaust holes (wind windows) 11h to 11h are provided around the cooling fan 11e and in the rear part of the motor case 11a. On the other hand, as shown in FIG. 2, intake holes 14c to 14c are provided on the rear surface of the motor mounting base portion 14b. When the cooling fan 11e is rotated by starting the electric motor 11, outside air is introduced from the intake holes 14c to 14c. The introduced outside air (cooling air) flows toward the rear side of the motor by the wind force, and the electric motor is cooled. The cooling air flowed to the rear side of the motor is exhausted to the outside through the exhaust holes 11h to 11h.
The length (machine length L0) of the electric motor 11 in the axial direction (left-right direction in FIG. 3) is an inner rotor type electric motor and is as short as a so-called brushless motor.

The distal end side of the output shaft 11d of the electric motor 11 protrudes from the motor case 11a and enters the blade case 14. The rotary blade 12 is directly attached to the tip of the output shaft 11d protruding into the blade case 14. The rotary blade 12 is firmly attached to the tip of the output shaft 11d while being sandwiched between the receiving flange 26 and the presser flange 27.
For this reason, the cutting tool 1 of this embodiment is a direct drive type cutting tool, and the rotary blade 12 rotates integrally at the same rotational speed as the electric motor 11. In this embodiment, the rotation speed Rm of the electric motor 11 is set to about 6,000 rotations per minute. For this reason, the rotation speed Rc of the rotary blade 12 is set to about 6,000 rotations per minute, which is the same as the rotation speed Rm of the electric motor 11.
The rotary blade 12 rotates counterclockwise as viewed from the front. On the front side of the blade case 14, the rotation direction of the rotary blade 12 is indicated by an arrow 14a.
The number of rotations of the rotary blade 12 is appropriately set according to the diameter, the material of the cutting material W, and the like. For example, the rotational speed of the rotary blade 12 having a diameter of about 185 mm to 190 mm is set to about 5,000 to 6,000 revolutions per minute when the cutting material W is wood, and the cutting material W is a metal material. In some cases, it is preferable to set the speed to about 3,000 to 4,000 revolutions per minute. In addition, the rotational speed of the rotary blade 12 having a diameter of about 110 mm to 125 mm is preferably set to about 7,000 to 9,000 revolutions per minute when the cutting material W is wood. Further, the rotational speed of the rotary blade 12 having a diameter of about 210 mm to 235 mm is preferably set to about 3,500 to 4,500 revolutions per minute when the cutting material W is wood.

The tool body 10 is supported on the upper portion of the base 2 via a front tilting support shaft 15 so as to be tiltable up and down. By changing the vertical tilt position of the tool body 10 with respect to the base 2, the projecting dimension of the rotary blade 12 to the lower surface side of the base 2 can be changed, whereby the cutting depth of the rotary blade 12 with respect to the cutting material W can be changed. Can be adjusted. As shown in FIG. 2, the rear side of the tool body 10 is supported by the base 2 via a curved guide member 3 called a depth guide that is attached to the upper portion of the base 2 in an upright state. By tightening the fixing screw 4 inserted through the guide hole 3a of the guide member 3 to the back side of the blade case 14, the tilting position of the tool body 10 with respect to the base 2 is fixed. The fixing screw 4 can be tightened by rotating the operation lever 5 attached to the front end of the back surface in the tightening direction. When the operation lever 5 is rotated to loosen the fixing screw 4, the tool body 10 can be tilted up and down with respect to the base 2, whereby the cutting depth of the rotary blade 12 can be changed.
The lower half of the rotary blade 12 protruding to the lower surface side of the base 2 is covered by the movable cover 16. The movable cover 16 is supported by the blade case 14 so as to be rotatable around the rotary blade 12. As shown in FIG. 1, the tip of the movable cover 16 is brought into contact with the cutting material W, and in this contacted state, the cutting tool 1 is moved in the cutting progress direction indicated by a white arrow in the drawing to rotate the rotary blade 12. Is cut into the cutting material W, whereby the movable cover 16 is gradually opened. A handle 17 is attached to the rear portion of the movable cover 16. The user can grip the handle 17 and rotate the movable cover 16 in the opening direction, thereby facilitating work such as replacement of the rotary blade 12.

A handle portion 30 is provided on the upper portion of the electric motor 11. As shown in FIG. 4, the handle portion 30 has a mountain-shaped loop shape extending from the upper portion of the electric motor 11 to the rear portion, and a standing portion 31 that rises upward from the upper portion of the electric motor 11, and an upper portion of the standing portion 31. A main grip portion 32 extending in a downward direction from the rear, and a coupling portion 33 for coupling the rear portion of the main grip portion 32 to the rear portion of the electric motor 11. The main grip portion 32 is a portion that the user holds with one hand, and a switch lever 35 is disposed on the lower surface side thereof. A front grip part 34 that is held by the user with the other hand is provided on the upper part of the standing part 31 so as to protrude forward.
A battery mounting base portion 36 is provided at the rear portion of the main grip portion 32. The battery pack B is mounted on the battery mounting base 36. The battery pack B can be slid upward to be removed from the battery mounting pedestal 36, and conversely slid downward to be attached to the battery mounting pedestal 36. The removed battery pack B can be used repeatedly by charging with a separately prepared charger. The electric motor 11 is activated using the battery pack B as a power source.
A lock lever 37 for locking the rotation of the output shaft 11 d is provided at the front portion of the electric motor 11. When the lock lever 37 is moved in the longitudinal direction, the rotation of the output shaft 11d is locked, and the operation of exchanging the rotary blade 12 is facilitated.

  According to the present embodiment configured as described above, since the rotary blade 12 is directly attached to the output shaft 11d of the electric motor 11 by the direct drive method, the rotational speed Rc of the rotary blade 12 and the rotational speed of the electric motor 11 are set. Rm agrees (ratio α = 1.0). For this reason, since the rotation speed Rm of the electric motor 11 matches the appropriate rotation speed Rc of the rotary blade 12, it can be rotated at a low speed, for example, at about 6,000 rotations per minute. Wind noise and vibration of the cooling fan 11e can be reduced, and as a result, noise and vibration reduction of the cutting tool 1 can be realized.

Various modifications can be made to the first embodiment described above. For example, by using a direct drive method (ratio α = 1.0) in which the rotary blade 12 is directly attached to the output shaft 11d of the electric motor 11, the outer rotor type electric motor 11 as a drive source is rotated at a low speed and the cutting is performed. Although the configuration for reducing the noise and reducing the vibration of the tool 1 has been illustrated, the rotational output of the electric motor 11 is set in the range of the ratio α = 0.5 to 2.0 with the shaft displacement mechanism 20 described below interposed. It is possible to obtain the same function and effect.
FIG. 5 shows a cutting tool 1 according to the second embodiment. About the member and structure similar to 1st Embodiment, the description is abbreviate | omitted using a same code | symbol. In the case of the second embodiment, the shaft displacement mechanism 20 is interposed between the electric motor 11 and the back surface of the blade case 14. The distal end side of the output shaft 11 d of the electric motor 11 enters the case 21 of the shaft displacement mechanism 20. A drive side gear 22 is attached to the tip of the output shaft 11 d that has entered the case 21. A driven gear 23 is meshed with the drive gear 22. The driven gear 23 is fixed to the spindle 25.
The drive gear 22 and the driven gear 23 have the same number of teeth, and the ratio α of the shaft displacement mechanism 20 is set to α = 1.0. For this reason, although not the direct drive system of the first embodiment, the rotational speed Rc of the rotary blade 12 (the rotational speed of the spindle 25) also matches the rotational speed Rm of the electric motor 11 in the second embodiment.
The spindle 25 is rotatably supported by the case 21 via bearings 25a and 25b. The tip end side of the spindle 25 protrudes into the blade case 14. The rotary blade 12 is attached to a spindle 25 protruding into the blade case 14. As in the first embodiment, the rotary blade 12 is firmly attached in a state of being sandwiched between the receiving flange 26 and the presser flange 27. The spindle 25 is parallel to the output shaft 11d of the electric motor 11 and is disposed at a core height D0 below the output shaft 11d whose core height from the lower surface of the base 2 is D1 (D1> D0). For this reason, the rotation center of the rotary blade 12 (the core height D0 of the spindle 25) is set at a position closer to the base 2 side than the core height D1 of the output shaft 11d of the electric motor 11, and thereby the rotary blade The maximum cutting depth for the 12 cutting materials W can be set large.
According to the cutting tool 1 of the second embodiment configured as described above, the rotation output of the electric motor 11 is transmitted to the rotary blade 12 via the shaft displacement mechanism 20 in which the ratio α is set to α = 1.0. The For this reason, when the appropriate rotation speed Rc of the rotary blade 12 is set to about 6,000 rotations per minute, for example, the rotation speed Rm of the electric motor 11 can be set to about 6,000 rotations per minute.
Conventionally, when an electric motor is used as a drive source for an electric tool, the outer rotor type electric motor 11 is used in the second embodiment in consideration of the fact that it is usual to rotate the motor at a high speed of about 25,000 revolutions per minute. Can be rotated at an extremely low speed of about 6,000 revolutions per minute, so that the wind noise and vibration of the cooling fan 11e of the electric motor 11 can be reduced, and the noise of the cutting tool 1 can be reduced. Vibration can be achieved.
The illustrated ratio α can be changed within a range of α = 0.5 to 2.0. The ratio α can be changed by changing the number of teeth of the drive gear 22 and the driven gear 23. Even when the ratio α is changed within a range of α = 0.5 to 2.0, the outer rotor type electric motor 11 as a driving source rotates at a very low speed (Rm = 3,000 rotations per minute) as compared with the conventional case. (12,000 revolutions) is sufficient, and the same effect can be obtained.
In addition, according to the second embodiment, the core height D0 of the rotary blade 12 can be set smaller than the core height D1 of the electric motor 11 via the shaft displacement mechanism 20, so that the maximum of the cutting tool 1 can be set. The cutting depth can be set large.

FIG. 6 shows a cutting tool 1 according to the third embodiment. In FIG. 6, some members such as the front grip 34 and the battery pack B are omitted. In the third embodiment, the configuration of the shaft displacement mechanism 40 is different from the gear meshing displacement mechanism of the second embodiment. The same members and configurations as those of the second embodiment are denoted by the same reference numerals, and the description thereof is omitted.
In the third embodiment, a belt transmission type displacement mechanism is provided in which a transmission belt 43 is stretched between a driving pulley 41 and a driven pulley 42. The driving pulley 41 and the driven pulley 42 have the same effective diameter. For this reason, the ratio α of the shaft displacement mechanism 40 in the third embodiment is also set to α = 1.0.
Also in the third embodiment, the rotation output of the electric motor 11 is transmitted to the rotary blade 12 through the shaft displacement mechanism 40 in which the ratio α is set to α = 1.0. For this reason, when the appropriate rotation speed Rc of the rotary blade 12 is set to about 6,000 rotations per minute, for example, the rotation speed Rm of the electric motor 11 can be set to about 6,000 rotations per minute.
Conventionally, when an electric motor is used as a drive source for an electric tool, the outer rotor type electric motor 11 is used in the third embodiment in consideration of the fact that it is usual to rotate the motor at a high speed of about 25,000 revolutions per minute. Can be rotated at an extremely low speed of about 6,000 revolutions per minute, so that the wind noise and vibration of the cooling fan 11e of the electric motor 11 can be reduced, and the noise of the cutting tool 1 can be reduced. Vibration can be achieved.
In addition, the ratio α exemplified in the third embodiment can be changed in a range of α = 0.5 to 2.0. The ratio α can be changed by changing the number of teeth of the driving pulley 41 and the driven pulley 42. Even when the ratio α is changed within a range of α = 0.5 to 2.0, the outer rotor type electric motor 11 as a driving source rotates at a very low speed (Rm = 3,000 rotations per minute) as compared with the conventional case. (12,000 revolutions) is sufficient, and the same effects as those of the first and second embodiments can be obtained in terms of noise reduction and vibration reduction.
Moreover, since the core height D0 of the rotary blade 12 can be set smaller than the core height D1 of the electric motor 11 according to the third embodiment, the maximum cutting depth of the cutting tool 1 can be set large.

DESCRIPTION OF SYMBOLS 1 ... Cutting tool 2 ... Base 3 ... Guide member (depth guide), 3a ... Guide hole 4 ... Fixing screw 5 ... Operation lever 10 ... Tool body 11 ... Electric motor (outer rotor type)
DESCRIPTION OF SYMBOLS 11a ... Motor case, 11b ... Stator, 11c ... Rotor, 11d ... Output shaft 11e ... Cooling fan, 11f, 11g ... Bearing, 11h ... Exhaust hole J ... Motor axis line 12 ... Rotary blade 14 ... Blade case 14a ... Arrow, 14b ... Motor mounting base, 14c ... Intake hole 15 ... Tilt support shaft 16 ... Movable cover 17 ... Handle 20 ... Axial displacement mechanism (second embodiment)
21 ... Case 22 ... Driving side gear 23 ... Driving side gear 25 ... Spindle 26 ... Receiving flange 27 ... Presser flange S ... Spindle axis (rotating axis of the rotary blade)
DESCRIPTION OF SYMBOLS 30 ... Handle part 31 ... Standing part 32 ... Main grip part 33 ... Coupling part 34 ... Front grip part 35 ... Switch lever 36 ... Battery mounting base part 37 ... Lock lever 40 ... Axial displacement mechanism (3rd Embodiment)
41 ... Drive side pulley 42 ... Driven side pulley 43 ... Transmission belt B ... Battery pack D0 ... Core height D1 of rotating blade (spindle) ... Core height L0 of electric motor ... Motor length

Claims (6)

A cutting tool comprising a base to be brought into contact with a cutting material and a tool main body supported on an upper portion of the base, and the tool main body having an outer rotor type electric motor as a drive source for rotating the rotary blade. The cutting tool according to claim 1, wherein the rotary blade is directly attached to an output shaft of the electric motor. The cutting tool according to claim 2, wherein when the diameter of the rotary blade is 185 mm to 190 mm, the rotation speed of the electric motor is set to 5,000 to 6,000 rotations per minute. 2. The cutting tool according to claim 1, comprising a shaft displacement mechanism for displacing a spindle, to which the rotary blade is attached, toward the base with respect to an output shaft of the electric motor. 5. The cutting tool according to claim 4, wherein a ratio α (Rm / Rc) between the rotational speed Rm of the electric motor and the rotational speed Rc of the rotary blade is set to α = 0.5 to 2 by the shaft displacement mechanism. Cutting tool set to .0. 6. The cutting tool according to claim 4 or 5, wherein the rotational speed Rm of the electric motor and the rotational speed Rc of the rotary blade are set equal by the shaft displacement mechanism.

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