JP2604192Y2 - Noise prevention structure for electric circular saw - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise prevention structure for an electric circular saw, such as a portable electric circular saw or an electric circular saw attached to a desktop type circular saw board.

[0002]

2. Description of the Related Art Conventionally, a drive fan of an electric circular saw is provided with a cooling fan, and this fan is attached to an output shaft of the drive motor, and rotates and stops as the drive motor starts and stops. When this fan rotates, cooling air is sucked into the motor housing through an air inlet provided on the rear surface of the motor housing, and the cooling air flows toward the front of the motor housing while cooling the armature and the field. The drive motor is cooled. An outlet is provided on the side of the housing of the normal drive motor, and the air that has cooled the drive motor is blown to the outside through the outlet.

[0003]

As described above, conventionally, a side of the motor housing is provided with an outlet for the cooling air sucked into the motor housing by the fan, and the cooling air is directly discharged to the outside through the outlet. Had to be exhausted. For this reason, when the cooling wind is exhausted from the outlet, a wind noise is generated, and in some cases, the state becomes the same as blowing a whistle, and a very loud wind noise is generated. Due to such noise, the worker must work while feeling uncomfortable, and the usability of the electric circular saw has been significantly impaired.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a noise prevention structure capable of improving the quietness of an electric circular saw and achieving a good feeling of use.

[0005]

Therefore, according to the present invention, in an electric circular saw provided with a centrifugal fan for cooling the driving motor on the output shaft of the driving motor, the electric rotating saw is located on the leeward side of the centrifugal fan. A plurality of slits are formed in the wall portion closing the front in the ventilation direction, and the wind generated by the centrifugal fan is blown out into the blade case via the slits, and all the slits forming the slits are formed. > Partition walls are where cutting chips are generated by cutting with a saw blade.
A noise prevention structure has been devised, characterized in that it is provided in a range avoiding the position and is arranged radially.

[0006]

[0007]

[0008]

According to the structure of the first aspect, the cooling air is sucked into the motor housing through the air inlet provided on the rear surface of the motor housing when the fan rotates. The sucked cooling air flows forward of the motor housing while cooling the drive motor. The cooling air flowing forward in this way
The air is blown into the blade case through a slit formed in the partition wall of the blade case that closes the front of the fan. At the time when the wind noise is blown into the blade case through the slit, the wind noise is muffled because the wind noise is inside the blade case. Therefore, the noise is greatly reduced as compared with the conventional structure in which the wind noise is blown directly to the outside. The wind blown into the blade case is weakened here, and then exhausted to the outside. In this way, since the sucked cooling air is blown into the blade case, it is not necessary to blow it directly to the outside through the side of the motor housing as in the related art, and further, as described above, the cooling air is blown into the blade case. Since the wind noise when blown out is muffled, the quietness of the marunoco is enhanced, and the feeling of use is improved.

Further, in addition to the above configuration, the fan
The air flow path of the generated wind is the same as the rotation direction of the fan.
Tilt down toward the slit while turning in the same direction
By providing the inclined portion , the cooling air ventilation passage reaching the slit is formed with an inclined portion which is turned in the same direction as the fan rotation direction and is inclined downward toward the slit. The wind is guided towards the slits without obstructing its flow, ie without generating turbulence, which further enhances the quietness of the marco.

Further, in the above structure, the slit is divided.
The partition wall to be formed is aligned with the axis of the output shaft of the drive motor.
With this configuration, the cooling air flowing to the slits blows against the partition walls and receives resistance to the flow. For this reason, the wind pressure in the ventilation passage is appropriately increased, and the wind pressure allows the cooling air to be smoothly blown into the blade case through the slit. As described above, since the wind is positively blown out by the wind pressure, the turbulence of the cooling air in the ventilation path is reduced, and the quietness of the marunouchi is also improved.

[0011]

Next, an embodiment of the present invention will be described with reference to FIGS. Note that, as usual, in the following description, unless otherwise specified, a direction along the cutting direction is referred to as a “front-back direction”, and left and right with respect to the cutting direction are referred to as a “left-right direction”.

FIG. 1 shows a right side surface of an electric circular saw to which a noise prevention structure of the present embodiment described below is applied. In the drawing, reference numeral 12 denotes a base of the circular saw, and a blade case 71 can be tilted on the base 12 around the pins 44 and 34 in the left-right direction (a direction perpendicular to the paper surface in FIG. 1). Is supported so as to be rotatable in the front-rear direction of the circular saw. As will be described later, by tilting the blade case 71 in the left-right direction of the circular saw, the inclination angle of the saw blade 56 can be adjusted (cutting angle adjusting mechanism of the saw blade 56), and the blade case 71 can be moved in the front-rear direction of the circular saw. By turning, the cutting depth of the saw blade 56 can be adjusted (cutting depth adjusting mechanism of the saw blade 56).

The base 12 is formed with a saw blade 56 and a cutout window 12c for projecting a safety cover 50 that mainly covers the teeth of the lower half of the saw blade 56.

A ruler mounting portion 13 for mounting a parallel ruler (not shown), which is mainly used when repeating parallel cutting, along the left-right direction of the circular saw is provided on the front portion of the base 12. Is provided. As shown in FIG. 3 or FIG. 6 to FIG.
A groove 13a formed on the upper surface of the front part 2 along the left-right direction, and a thumb screw 13 attached to the front and rear of the groove 13a so as to be screwed into the groove 13a.
b, 13b (omitted in FIG. 3). According to the ruler mounting portion 13, the parallel ruler is attached to the groove 1
The parallel ruler is fixed at a predetermined position by being fitted into the inside 3a and tightening the two thumb screws 13b, 13b. Here, conventionally, for example, Japanese Utility Model Laid-Open No. 4-45701
As disclosed in Japanese Unexamined Patent Publication (Kokai) No., there was a problem that the thumb screw was provided only in one place, so that the play of the ruler became large and it was not only difficult to use, but also accurate measurement was difficult. . In this regard, according to the ruler mounting portion 13 of this example, since the parallel ruler is fixed by the two thumb screws 13b, 13b provided at a fixed interval, it must be firmly fixed without rattling. Can be. Also, since the thumb screws 13b, 13b are provided near the left and right ends of the groove 13a, only one of the thumb screws 1 is provided.
By using 3b, the parallel ruler can be fixed in a state that the parallel ruler protrudes in both front and rear directions of the base 12 as compared with the configuration provided in one place as in the related art, and the measurable range of the parallel ruler is expanded. .

Next, the blade case 71 is formed in a semicircular shape on the back side of the saw blade 56 (to the left of the circular saw) so as to cover substantially the upper half thereof. A substantially arc-shaped blade case cover 7 is provided on the right side of the blade case 71.
The blade case cover 70 and the blade case 71 cover the upper half of the saw blade 56, particularly the teeth, from both left and right sides.

Hereinafter, the support structure of the blade case 71 will be described in detail. Notch window 1 of base 12
2c, that is, in FIG.
The supporting edges 12a and 12b are provided on the upper surface near the front end and on the rear end.
Are formed in a rising shape, and the front supporting edge 12a
, The angular plate 7 is supported via the pins 44 so as to be rotatable in the left-right direction (the direction perpendicular to the plane of FIG. 1) of the circular saw.

As shown in FIG. 9, the angular plate 7 has an arc-shaped long slot 7b and a bifurcated support 7a. A thumb screw 4 is inserted into the long slot 7 b, and the thumb screw 4 is screwed into the grip 1. The grip 1 is provided as a grip portion for an operator to grip the mushroom when carrying the mushroom or moving the mushroom along a predetermined path during work, and is provided on the upper surface of the base 12 in a rising state. Directly fixed to. According to the above configuration, when the thumb screw 4 is loosened, the angular plate 7 can be rotated in the left-right direction of the circular saw around the pin 44, and the saw blade 56 is moved right and left with respect to the cutting direction by the support edge 12b described later. To adjust the tilt angle. Conversely, when the thumb screw 4 is tightened, the angular plate 4 is fixed so as not to rotate, and the saw blade 56
Can be fixed at a constant inclination angle. As shown in the figure, an angle scale 7f is displayed on the side of the long slot 7b, and a pointer 7g is provided on the grip 1. The inclination angle of the saw blade 56 can be accurately determined by the angle display indicated by the pointer 7g. It can be set to.

Next, the forked support portion 7a of the angular plate 7 is provided with left and right support edges 7d and 7e forming a forked portion, and between the two support edges 7d and 7e, FIG. 3 and FIG.
, A supporting edge 71i formed at the front lower end of the blade case 71 is inserted, and a pin 41 is inserted across the three supporting edges 7d, 7e, 71i. . As a result, the blade case 71
It is rotatably supported on the angular plate 7 with respect to the angular plate 7 in the front-rear direction (the direction perpendicular to the paper surface in FIG. 9) of the circular saw. The length of the pin 41 is set so as to slightly protrude from the right side surface of the right supporting edge 7d in the inserted state.

Here, a parallel pin is used as the pin 41, and concentric holes 7c are formed in both support edges 7d and 7e of the forked support portion 7a for inserting the pin 41 as shown in the figure. The hole 7c is formed with a bottom at the support edge 7e on the left side (the right side in FIG. 9). For this reason, when assembling the blade case 71 to the angular plate 7, the pin 41 can be inserted into the hole 7c only from the right side (the left side in FIG. 9) of the circular saw. After the pins 41 are inserted, the blade case cover 70 is fixed to the blade case 71 by screws 70a to 70a in a superposed manner from the right. On this occasion,
An overhanging edge 70 b formed at the front lower end of the blade case cover 70 is pressed against the end face of the protruding portion of the pin 41. Thus, after the pins 41 are inserted into the holes 7c, the pins 41 can be prevented from coming off simply by attaching the blade case cover 70 without applying any special means such as bolts or clips.

Next, as shown in FIG.
b, the depth guide 2 constituting the cutting depth adjusting mechanism of the saw blade 56 can be tilted left and right with respect to the cutting direction via the pin 34 arranged coaxially with the pin 44 of the front supporting edge 12a. It is supported by. An arc-shaped long slot 12d (see FIG. 20) and a support hole 12f for supporting the pin 34 are formed in the support edge 12b.
A support hole 2d for supporting the hole 2b and the pin 34 is formed in the end 2e abutting on the support edge 12b. The screw portion 31a of the thumbscrew 31 is inserted into the hole 2b and the slot 12d in a state where the screw portion 31a is prevented from rotating. According to this, when the thumb screw 31 is tightened, the depth guide 2 is fixed to the support edge 12b,
When the thumbscrew 31 is loosened, the depth guide 2 can be tilted left and right about the pin 34.

Here, as shown in FIG.
A conical portion 12e is formed on the inner surface of the depth guide 2 where the end 2e of the depth guide 2 abuts and around the long slot 12d. In the diagram (a), the conical portion 12e is shown with grid-like hatching. This conical portion 12
"e" forms a part of the inner peripheral surface of the cone whose vertex is the center of the support hole 12f, and is formed as a concave curved surface which is inclined downward from the lower portion to the upper portion as shown in FIG. .

On the other hand, as shown in FIG.
A conical portion 2c is also formed around the hole 2b on the outer surface of the end portion 2e, which is in contact with the support edge 12b. The conical portion 2c is also shown with a grid-like hatching in FIG. This conical portion 2c
Is a part of the outer peripheral surface of the cone whose vertex is the center of the support hole 2d, and is formed as a convex curved surface that is inclined upward from the lower part to the upper part as shown in FIG. 2e is in contact with the support edge 12b,
Is formed so as to come into contact with the surface.

As described above, the supporting edge 12b and the supporting edge 1
Conical portions 12e and 2c are formed on opposite surfaces of the end portion 2e of the depth guide 2 supported on the pin 2b via the pin 34, and the depth guides are formed in a state where the conical portions 12e and 2c are in contact with each other. 2 are supported by the support edge 12b. For this reason, when the depth guide 2 is tilted, the two conical portions 12e and 2c are always slid in contact with each other, and
In addition, since the two conical portions 12e and 2c form the same conical side having the center of the pin 34 as an apex, the depth guide 2 tilts smoothly around the pin 34.

Here, in general, the base of the circular saw is often a die-cast part, and therefore, the supporting edge 1
It is necessary to set a predetermined draft in the portion corresponding to 2b. However, there is a problem that the depth guide supported by the supporting edge is inclined due to the draft, and as a means for solving this problem, for example, as disclosed in Japanese Utility Model Laid-Open No. 4-76403, is disclosed. There has been a method of providing a projection for canceling the draft angle.
However, according to this method, since the supporting edge and the depth guide are supported at points, there is a problem that the depth guide rattles and the supporting edge is damaged by the tip of the projection. In this regard, according to the configuration of this example, the draft is set by the fact that the conical portion 12e of the support edge 12b is formed to be inclined downward from the lower portion to the distal end portion, as described above, and furthermore, Depth guide 2 is supporting edge 1
2b while being supported by the two conical portions 12
e and 2c are in the state of the surface contact.

From this, it is possible to firmly support the depth guide 2 without backlash while securing a draft when the base 12 is a die-cast part, and the tightening force by the thumb screw 31 is dispersed. Therefore, the supporting edge 12b or the end 2e of the depth guide 2 is not damaged, so that there is no problem as in the case of the conventional hitting.

Next, the depth guide 2 is formed in a substantially L-shape, as is well shown in FIG. A slot 2a is formed at the distal end as shown in the figure. The shaft 3a of the fixed lever 3 is formed in the slot 2a.
Is inserted.

That is, as shown in FIGS. 3 and 5, the shaft portion 3a of the fixed lever 3 is
4 is inserted through a sleeve 81 supported at a lower portion of the sleeve 4 and further has a long slot 2a formed in the depth guide 2, a hole 71a formed in the blade case 71, and a long slot 29a formed in a live knife holder 29 described later. Has been inserted. The shaft part 3 in which each part is inserted as described above
A flange portion 3b and a chamfered portion 3c are formed at the tip of the a.
And the chamfered portion 3c is located in the long slot 29a of the riving knife holder 29. For this reason,
The shaft portion 3a is mounted so as not to be able to come off and rotate in a downward direction in FIG. 3 (to the right in FIG. 5). On the other hand, a screw portion 3d is formed at the rear end of the shaft portion 3a, and a hexagon nut 3e is screwed into the screw portion 3d, and the fixed lever 3 is attached to the hexagon nut 3e.

A U-ring 3f is used to fix the fixing lever 3 and the hexagon nut 3e. That is, the hexagon nut 3e is non-rotatably fitted into the hexagon hole 3g provided in the fixed lever 3, and then the cut groove 3h formed in the fixed lever 3 and the cut groove 3 formed in the hexagon nut 3e.
The fixing lever 3 and the hexagon nut 3e are fixed to each other so that they cannot rotate and cannot be pulled out by inserting the U ring 3f so as to be inserted into the i. Therefore, the fixing lever 3 can be removed from the shaft portion 3a only by removing the U-ring 3f from the cut grooves 3h and 3i. That is, when the fixed lever 3 is attached to the shaft portion 3a, the motor housing 67 or the base 1
Therefore, when the fixed lever 3 is removed from the shaft portion 3a, it cannot be removed integrally with the hexagon nut 3e. In this regard, fixed lever 3 and hexagon nut 3
e is fixed by the U ring 3f,
The fixed lever 3 can be easily removed from the shaft portion 3a simply by removing the ring 3f from the cut grooves 3h and 3i. Conversely, the hexagon nut 3e is connected to the hexagonal hole 3g of the fixed lever 3.
After the U-ring 3f is inserted into the
h, 3i, the mounting of the fixed lever 3 is completed. Accordingly, the structure of the circular saw can be simplified and its disassembly and assemblability can be improved as compared with the conventional case where a leaf spring or a fixing screw is used, for example.

As described above, the fixing lever 3 is screwed into the shaft portion 3a via the hexagon nut 3e fixed by the U-ring 3f. For this reason, when the fixed lever 3 is rotated, the shaft portion 3a does not rotate, so that the fixed lever 3 is screwed into the shaft portion 3a, and the shaft portion 3a cannot be removed by the flange portion 3b. The sleeve 81 is pressed against the depth guide 2, whereby the depth guide 2 and the blade case 71 are fixed to each other.
9 is also fixed.

On the other hand, when the fixing lever 3 is loosened, the distance between the flange portion 3b of the shaft portion 3a and the sleeve 81 is increased, so that the fixing between the depth guide 2 and the blade case 71 is released. The saw blade can be rotated around the pin 41 in the front-rear direction, whereby the cutting depth can be adjusted by changing the size of the saw blade 56 protruding below the base 12.

As shown in FIGS. 3 and 4, a substantially cylindrical pedestal 71b is integrally formed on the back surface of the blade case 71 supported by the base 12 as described above. The motor housing 67 is attached to the base 71b. The aforementioned D-shaped handle portion 74 is integrally formed on a side portion of the motor housing 67.

As shown in FIG. 4, inside the motor housing 67, a drive motor for the circular saw mainly comprising an armature 76 and a field 66 is formed. The output shaft 76a of the drive motor, that is, the shaft of the armature 76 is rotatably supported by the motor housing 67 by bearings 76b and 76c. In addition,
The front bearing 76b is housed in a holder 71f formed at the bottom of the pedestal 71b. As shown in FIG. 13, a rubber pin 71g made of elastic rubber is partially provided in the holder 71f. The rubber pin 71g prevents the bearing 76b from coming off because the rubber pin 71g is mounted so as to protrude to the peripheral side.

Returning to FIG. 4, the front bearing 76b and the armature 76 are located near the front end of the output shaft 76a.
Between them, a centrifugal fan 73 is attached. Therefore, the fan 73 rotates with the activation of the drive motor, whereby air having a flow rate corresponding to the rotation speed is sucked into the motor housing 67 through an air inlet 67 a provided on the rear surface of the motor housing 67. The path of the sucked wind is indicated by an arrow in the figure. That is, the wind sucked into the motor housing 67 flows from the rear portion of the motor housing 67 to the whole, and cools the armature 76, the field 66, and the like during the flow .

Next, a baffle plate 64 is mounted on the inner peripheral side of the motor housing 67 so as to project between the fan 73 and the drive motor, that is, the armature 76. Since the baffle plate 64 has a substantially ring shape, there is a sufficient gap between the baffle plate 64 and the output shaft 76a.
The wind that was sucked into and reached the front was narrowed down,
After that, this wind is blown forward of the fan 73 (left side in the figure).

Since the baffle plate 64 has a loose mortar shape, it is squeezed and then blown forward by a smooth flow without generating turbulence. The wind blown in front of the fan 73 in this manner is applied to the pedestal 71b.
Is blown into the blade case 71 through a plurality of slits 71c to 71c formed at the bottom of the blade case 71. Here, as shown in FIG. 13, the slits 71c to 71c and the partition walls 71e to 71e forming each slit 71c are
1b, the spindle 60
Are formed radially around the center of the axis. Further, each partition wall 71e to 71e is provided with an output shaft 76a of the drive motor.
, That is, substantially perpendicular to the ventilation direction.

Further, at the bottom of the pedestal 71b, FIG.
, A smoothly curved inclined portion 71d descending from the vicinity of the spindle 60 toward the slits 71c to 71c in a counterclockwise direction is formed. Also, this inclined portion 71
d and the pedestal 71 along the slits 71c to 71c
The inner peripheral wall surface 71h of b is a smooth peripheral surface having substantially no edges or stepped portions that cause turbulence. The air blown toward the front of the fan 73 after being narrowed down by the baffle plate 64 flows into the ventilation path formed by the inner peripheral wall surface 71h and the inclined portion 71d.

As shown in FIG. 6 or 7, a partition wall 82a is formed along the upper peripheral edge of the blade case 71, and a dust collection path 82 is provided.
The illustrated right end of the dust collection path 82 is opened inside the blade case 71 to be an inlet 82b for cutting chips, and the left end is closed to be a terminal end 82c. The cover 70 is provided with a discharge port 83 as shown in FIG. In this outlet 83,
Although not shown, a dust bag is attached. According to the dust collection path 82 thus formed, the cutting chips generated by the saw blade 56 rotating in the counterclockwise direction in FIG. 6 generate the cutting force (centrifugal force) of the saw blade 56 and the wind generated thereby. Is blown toward the inflow port 82b, and then stored in the dust collection bag from the inflow port 82b via the dust collection path 82 and the discharge port 83. Here, since the partition wall 82a has a function of separating the wind blown out through the slits 71c to 71c from the dust collection path 82 so that the wind is not blown into the dust collection path 82a, the slit 71c Blowing air into the blade case 71 through -71c does not adversely affect the cutting chip discharge efficiency.

Next, returning to FIG. 4, the power transmission section of the drive motor will be described. That is, the output shaft 7 of the drive motor
A gear portion 76d is formed at the tip of 6a, and the gear portion 76d is meshed with the driven gear 59. The driven gear 59 is fixed to the spindle 60 described above, and the spindle 60 is disposed by bearings 61 and 57 in parallel with the output shaft 76a and is rotatably supported.
The bearing 61 on the rear side (right side in the figure) is
b, which is supported by the bottom of the front side (left side in the figure)
Reference numeral 7 is also supported on the inner peripheral side of a ring-shaped bearing box 49 attached to the bottom of the base 71b. The distal end of the spindle 60 supported in this manner protrudes into the blade case 71, and the distal end protruding portion has a disc-shaped saw blade through both outer and inner flanges 54 and 55 fixed by bolts 53. 56 is detachably fixed.

At the rear end (right end in the figure) of the spindle 60, for example, the bolt 53
A spindle lock mechanism for locking the spindle 60 so as not to be rotatable is provided for the convenience of loosening or tightening the spindle. According to this spindle lock mechanism, the replacement operation of the saw blade 56 can be easily performed on the spot without separately preparing a predetermined tool or the like.

That is, as shown in FIGS. 4, 13 and 14, a flat portion 60a is formed at the rear end of the spindle 60. The flat portion 60a is disengaged from the flat portion 60a in the rotational direction. A lock plate 63 having a locking portion 63a is slidably supported at a joint between the pedestal portion 71b and the motor housing 67.

As shown in FIG. 13, the lock plate 63 is inserted and supported in a state of straddling between grooves 63b formed in the peripheral wall of the base 71b. The left end (shown in the figure) protrudes to the side of the base 71b. On the other hand, on the periphery of the baffle plate 64, as shown in FIGS. 14 and 15, the projections 64a, 64b correspond to the two grooves 63b, 63b.
a is formed so as to protrude.
a are inserted into the grooves 63b, 63b, respectively.
Thereby, the groove portions 63b, 63b of the lock plate 63
Of the lock plate 6
3 is supported to slide smoothly without rattling. Therefore, in assembling the spindle lock mechanism, the spindle lock mechanism is inserted into both groove portions 63b, 63b of the pedestal portion 71b across the lock plate 63, and then the protrusion portions 64a,
The baffle plate 64 is arranged so as to cover the pedestal portion 71b in a state where the lock plate 64a is inserted into both the groove portions 63b, 63b, and then the motor housing 67 is fixed to the pedestal portion 71b, whereby the lock plate 63 and the The baffle plate 64 is supported in a predetermined state.

The locking portion 63a is formed at the center of the lock plate 63.
3a is a circular hole 63c having a diameter through which the spindle 60 can be inserted.
And a locking groove 63 formed continuously with the circular hole 63c.
d. The width of the locking groove 63 d is larger than the width of the two-sided width portion 60 a of the spindle 60 and smaller than the diameter of the spindle 60.

As shown in FIGS. 14 and 15, a locking piece 63 is provided on the lower surface of the lock plate 63.
e is cut and raised so as to protrude downward. On the other hand, a long groove-shaped and stepped concave portion 62a is formed at the bottom of the pedestal portion 71b. The compression coil spring 62 is accommodated in the concave portion 62a so as to float from the bottom surface, and the locking piece 63e is inserted between the illustrated left end surface of the compression coil spring 62 and the left side wall of the concave portion 62a.

According to the lock mechanism configured as described above, the spindle 60 is locked as follows. That is, in a state where the two-face width portion 60a of the spindle 60 is positioned substantially horizontally as shown in the drawing, if the operator presses the tip projecting portion of the lock plate 63 against the compression coil spring 62, the lock plate 63 is not shown. Sliding rightward, the two-face width portion 60a is relatively circular hole 63c.
The spindle 60 is inserted into the locking groove 63d from inside, whereby the spindle 60 is locked so as not to rotate.

On the other hand, when the operator releases his / her finger from the lock plate 63, the lock plate 63
2, the two-face width portion 60a is relatively removed from the locking groove 63d and moved into the circular hole 63c, whereby the spindle 60 returns to the rotatable state again.

Next, around the saw blade 56 attached to the tip of the spindle 60 and rotatably disposed in the blade case 71, the above-described safety cover 50 is provided.
And a riving knife 30.

FIG. 3 or FIG.
As is clear from FIG. 5, the back cover 50a and the front cover 50b are provided to cover the saw blade 56 from both the front and back sides. The back cover 50a is formed in a semicircular shape so as to cover substantially the lower half of the saw blade 56 from the back side, and is rotated on the pedestal portion 71b of the blade case 71 around the spindle 60 in the front-rear direction as described below. Supported as possible. On the other hand, the front cover 50b is formed in an arc shape so as to cover substantially the lower half circumference of the saw blade 56 from the front side. The back cover 50a and the front cover 50b formed as described above are integrally joined at both ends thereof to form the two covers 50.
A safety cover 50 is formed by superimposing a certain gap between a and 50b. The saw blade 56 is arranged with its peripheral edge inserted in the gap between the covers 50a and 50b.

On the other hand, the riving knife 30 is provided for the purpose of properly maintaining the gap between the cut pieces immediately after cutting to reduce the cutting resistance of the saw blade 56 and preventing the so-called kickback of the saw blade 56. As shown in FIGS. 1, 6, and 7, the saw blade 56 has a substantially crescent-shaped curved shape.
And has substantially the same plate thickness. This riving knife 3
Numeral 0 is attached to the tip of the riving knife holder 29. The riving knife holder 29 is rotatable on the pedestal portion 71b of the blade case 71 about the spindle 60 in the same manner as the safety cover 50 as described below. It is supported by. By rotating the riving knife holder 29, the riving knife 30 is rotated.
Is movable along the outer periphery of the saw blade 56.

The safety cover 50 and the riving knife holder 29 are supported by the pedestal 71b of the blade case 71 as follows. As shown in FIG. 3 or FIG. 4, the above-described bearing box 49 is attached to the inner surface of the pedestal portion 71b of the blade case 71, and the bearing box 49 is formed in a ring shape and has an inner peripheral side. As described above, the bearing 57 is supported and the spindle 60 is supported by the bearing 57. As shown in FIGS. 3 and 4, the outer peripheral side of the bearing box 49 has a small-diameter portion 49a on the distal end side. And a large-diameter portion 49b at the center, and two flat surfaces 49b as shown in FIGS.
c and 49c are chamfered in parallel. This chamfer will be further described later.

On the other hand, as shown in FIG. 3, a boss 50c is provided at the center of the upper portion of the back cover 50a of the safety cover 50 so as to slightly protrude toward the back surface. The above bearing box 49
A supporting hole 50d having a diameter capable of inserting the small-diameter portion 49a is formed. A supporting hole 29b having a diameter into which the large-diameter portion 49b of the bearing box 49 can be inserted is formed at the base end of the riving knife holder 29. As shown in the drawing, the support holes 29b are formed with parallel projecting edges 29d, 29d projecting inward at a certain interval from each other, which will be further described later. Then, first, the riving knife holder 29 is fitted to the large-diameter portion 49b via the support hole 29b, and then the safety cover 50 is fitted to the small-diameter portion 49a via the support hole 50d. A bearing retainer 51 is attached to the end face of the bearing box 49 by using a screw 5.
2 and 52, the safety cover 50
And a riving knife holder 29 are rotatably supported.

The upper end of the safety cover 50 supported as described above and the upper part of the blade case 71 (the dust collection path 82)
, Near the end portion 82c), the tension coil spring 27 is hooked as shown in FIG. 1, FIG. 6, and FIG. Therefore, the safety cover 50 is urged in the counterclockwise direction in the figure, and can rotate in the clockwise direction (the direction in which the saw blade 56 is exposed) against this urging force. When the external force that causes the saw blade 56 to rotate is removed, the tension coil spring 27 rotates counterclockwise to return to the state where the saw blade 56 is covered.

A stopper rubber 37 having a cylindrical shape is attached to a lower portion of the inner surface of the blade case 71 as a stopper for restricting the rotation of the safety cover 50 in the counterclockwise direction. That is, a cylindrical projection 38 having a cylindrical shape with an outer diameter slightly larger than the inner diameter of the stopper rubber 37 as shown in FIG. An arc projection 39 integrally formed in a standing shape and having an arc surface on the outer periphery of the column projection 38 concentric with the column projection 38 and having an inner diameter slightly smaller than the outer diameter of the stopper rubber 37.
Are integrally formed. Therefore, the interval between the projections 38 and 39 is slightly smaller than the thickness of the stopper rubber 37.

According to this, the stopper rubber 37 is inserted between the cylindrical projection 38 and the arc projection 39 while inserting the cylindrical projection 38 on the inner peripheral side as shown in the figure.
7 is fixed at a predetermined position by press-fitting a part thereof. According to the stopper rubber 37 attached in this manner, the safety cover 50 covers almost the entire portion of the saw blade 56 protruding below the base 12 as shown in FIG. 1 or FIG. Thus, further rotation in the counterclockwise direction is prevented.

Further, a roller 47 is attached to the tip of the safety cover 50, and when the roller 47 is lightly pressed against the material to be cut in the cutting operation, the safety cover 50 rotates clockwise with the light. The lower portion of the saw blade 56 is appropriately exposed and applied to the workpiece. During the cutting operation, since the roller 47 is constantly pressed against the workpiece by the tension coil spring 27,
The exposed portion of the saw blade 56 is reduced as much as possible, whereby the safety of the cutting operation is ensured. Since the roller 47 is constantly pressed against the workpiece, the saw blade 5
As the cutting depth of 6 increases, the safety cover 50 is relatively rotated clockwise, so that the exposed portion of the saw blade 56 increases smoothly. Furthermore, as the cutting tool is moved along the cutting line with the progress of the cutting operation, the roller 47 also rolls on the upper surface of the workpiece to be cut, so that the cutting tool can be moved smoothly without any resistance.

Next, the driving knife 30 is attached to the rear end of the driving knife holder 29 supported by the bearing box 49 as described above, as described above. That is, on the front surface of the tip of the riving knife holder 29, FIGS.
As shown in FIG. 17, two disk-shaped projections 29c, 29c
Are fixed at predetermined intervals on an axis having a certain angle with respect to the tip line of the overhanging edge 29d formed in the support hole 29b. On the other hand, a long slot 30a is formed in the upper part of the riving knife 30 so that the projection 29c can be inserted almost without looseness.

According to this, the protrusion 29 is formed in the long slot 30a.
c, 29c, and the upper part of the riving knife 30 is overlapped with the tip of the riving knife holder 29.
When the bolt 28 is tightened, the driving knife 30 is fixed to the driving knife holder 29. Here, for example, when fixing with only two bolts as disclosed in Japanese Utility Model Publication No. 62-34725, the gap between the bolts and the long groove holes becomes large to some extent.
As a result, rattling of the riving knife is increased, which may result in contact with a saw blade or the like. In this regard, according to the mounting structure of the present embodiment, since the driving knife 30 is fixed only by tightening one bolt 28, the number of components is reduced, and the mounting operation of the driving knife 30 is simplified. Moreover, two projections 29c, 29 are provided in the long slot 30a.
Since c is inserted in a state where there is almost no gap, it is possible to position the living knife 30 with respect to the living knife holder 29 and fix it in a state without rattling.

The long slot 29a is formed in the center of the riving knife 30.
The shaft portion 3a of the fixed lever 3 is inserted into a, and the flange portion 3b of the shaft portion 3a is in contact with the side edge of the long slot 29a to prevent the shaft portion 3a from coming off. This is as described above.

Next, the support structure of the living knife holder 29 will be described. The riving knife holder 29 is supported so as to rotate in conjunction with the rotation of the blade case 71 with respect to the base 12. That is, as described above, the supporting hole 29b is formed at the base end of the riving knife holder 29.
The holding knife holder 29 is rotatably supported by the large-diameter portion 49b of the bearing box 49 via the shaft.
As shown in FIGS. 6 and 7, a link arm 40 is mounted between the reference numeral 9 and the angular plate 7 described above.

The tip of the link arm 40 has a pin 4
The pin 40a is rotatably inserted into a coupling hole 29e provided below the base end of the riving knife holder 29, so that the distal end of the link arm 40 is locked. A pin is connected to the base end of the bing knife holder 29. On the other hand, the rear end of the link arm 40 is rotatably connected to the lower portion of the bifurcated support portion 7a of the angular plate 7 via a pin 40b. In addition,
As shown in FIGS. 4 and 18, a part of the distal end of the link arm 40 is inserted into an arc groove 49 d to be described later together with the protruding edge 29 d of the riving knife holder 29. This will be described in more detail.

As described above, the living knife holder 29
And the angular plate 7 on which the blade case 71 is supported, the link arm 40 is attached, so that the blade case 71 is centered on the pin 41 in order to adjust the cutting depth of the saw blade 56 as described above. 6 and 7, the rotation center (ie, the spindle 60) of the riving knife holder 29, the saw blade 56, and the safety cover 50 is, of course, centered on the pin 41. since arc moves on the circumference upward to, but saw blade 56 and the safety cover 50 is to move upward together with the blade cases 71, riving knife holder 29 is its center of rotation (i.e. The spindle 60) moves upward in an arc while being relatively rotated downward by the action of the link arm 40.
That is, the riving knife holder 29 is rotated counterclockwise with respect to the saw blade 56 while its rotation center moves upward.

[0061] According supporting structure of the riving knife holder 29, riving knife 30 attached to the tip of the riving knife holder 29 is opposed along the periphery of the saw blade 56 is moving upward The lower relative position of the saw blade 56 and the lower end of the saw blade 56 always protrudes slightly downward from the tip of the riving knife 30. , So that the wedge action of the riving knife 30 is always exerted irrespective of the position of the saw blade 56 (the position of the spindle 60 as the center of rotation).

The upward movement of the blade case 71 is performed by moving the blade guide 71 into the slot 2a of the depth guide 2 as shown in FIG.
The shaft portion 3a of the fixed lever 3 comes into contact with the upper end of the fixed lever 3 to be regulated. On the other hand, as shown in FIG. 6, the downward movement of the blade case 71 is restricted by the shaft portion 3a abutting on the lower end of the long slot 2a. When the upward or downward movement of the blade case 71 is restricted,
The saw blade 56, the safety cover 50 and the riving knife holder 29 also cannot be moved upward or downward at this time.

As described above, in the support hole 29b of the riving knife holder 29, projecting edges 29d, 29d are formed at two opposing positions so as to extend parallel to the inner peripheral side at a fixed interval from each other. Figure 6
As shown in FIGS. 7 and 17, the large-diameter portion 49b of the bearing box 49 inserted into the inner peripheral side of the support hole 29b.
Are formed with arc grooves 49d, 49d of a predetermined depth. That is, the small diameter portion 49a and the large diameter portion 49b of the bearing box 49 have the two flat surfaces 49c, 49c chamfered in parallel as described above.
As shown in the figure, the arc grooves 49d, 4 are formed in a certain range in the clockwise direction from the middle of the two planes 49c, 49c.
9d is formed, and the depth of the two arc-shaped grooves 49d substantially matches the overhang dimension of the overhang edge 29d of the riving knife holder 29.

When the blade case 71 is at the lower end position as shown in FIG.
Most of the projecting edge 29d enters the arc groove 49d, and when the blade case 71 is at the upper end position as shown in FIG. 7, a very small portion of the overhanging edge 29d is in the arc groove 49d. It is in a state of having entered. In the process of rotating the blade case 71 from the lower end position shown in FIG. 6 to the upper end position shown in FIG. 7, the riving knife holder 29 relatively rotates downward (counterclockwise). In the meantime, the overhanging edges 29d, 29d are always between the arcuate grooves 49d, 4d.
9d.

Further, as described above, the lower edge of the base end of the riving knife holder 29, that is,
A coupling hole 29e is formed near 9d.
9e, the pin 40a of the link arm 40 is inserted.
9 and a part of the distal end of the link arm 40 is provided between the overhanging edge 29d and the lower side wall in FIG. 18 of the arc groove 49d as shown in FIGS. It is in a state of being sandwiched. In the process of rotating the blade case 71 from the lower end position shown in FIG. 6 to the upper end position shown in FIG. The shape of the side wall of the groove 49d is set.

As described above, since both the distal end of the link arm 40 and the overhanging edge 29d of the riving knife holder 29 are inserted into the arc-shaped groove 49d, the axial direction of the pin 40a of the two members 40, 29 is set. Therefore, the pin 40a cannot be removed from the coupling hole 29e, so that the link arm 40 is attached to the living knife holder 29 in a state where the pin coupling is not released.

The arc-shaped grooves 49d, 49d of the large-diameter portion 49b formed as described above and the projecting edge 29 of the support hole 29b are formed.
According to FIGS. d and 29d, in order to remove the riving knife holder 29 from the bearing box 49, the large-diameter portion 4
By adjusting the relative position of the riving knife holder 29 in the circumferential direction with respect to 9b, the overhanging edges 29d, 29d of the support holes 29b are respectively aligned in parallel with the plane 49c of the large diameter portion 49b as shown in FIG. Double overhang 29
It is necessary that d, 29d be out of the arc groove portions 49d, 49d. Hereinafter, the circumferential position of the driving knife holder 29 with respect to the large-diameter portion 49b in this state is referred to as the “assembly position” of the driving knife holder 29.

Then, as described above, the link arm 40
Is sandwiched between the overhanging edge 29d and the side wall of the arc groove 49d, so that the
After the bearing box 4 is positioned at the "assembly position"
9 is released only from the large-diameter portion 49b of the connector 9 in the state of being removed from the large-diameter portion 49b.
The connection hole 29e can be pulled out of the hole 0a.

From this, the living knife holder 2
When assembling the bearing 9 into the bearing box 49, the pin 40 a of the link arm 40 is inserted into the coupling hole 29 e of the driving knife holder 29 with the riving knife holder 29 at the “assembly position”. The arm 40 is pin-connected to the living knife holder 29,
After the large diameter portion 49b is inserted into the support hole 29b, the blade case 71 is rotated downward to shift the riving knife holder 29 from its "assembly position". As a result, the riving knife holder 29 is restricted from moving in the axial direction so that the riving knife holder 29 cannot be detached from the large-diameter portion 49b, and the pin 40a of the link arm 40 is connected to the coupling hole 29e. Therefore, the pin connection of the link arm 40 cannot be disengaged.

The blade case 7 remains in this state.
By rotating the blade 1 downward, the slot 71 a of the riving knife holder 29 and the hole 71
a and the long slot 2a of the depth guide 2 can be aligned so that the shaft portion 3a of the fixed lever 3 can be inserted into these three holes 29a, 71a, 2a. It is in a state where it cannot be removed from the large diameter portion 49b of the bearing box 49, and the pin connection of the link arm 40 cannot be released.

As described above, the assembled state of the mushroom,
In other words, the shaft portion 3a of the fixed lever 3 is connected to the long slot 29a of the
When the blade case 71 is inserted into the first hole 71a and the long slot 2a of the depth guide 2, the blade case 71 can be turned up and down within the range in which the shaft portion 3a can move in the long slots 29a and 2a as described above. However, as long as the blade case 71 is rotatable, the driving knife 2
9 does not reach the “assembly position” and the three holes 29
Only when the blade case 71 is further rotated upward while the shaft portion 3a is withdrawn from the shaft portions a, 71a and 2a and the riving knife holder 29 is further rotated counterclockwise relatively. Holder 29
Is positioned at the “assembly position”.
The length of 9a, 2a, the position of the hole 71a, the positional relationship of the overhanging edges 29d, 29d with respect to the two planes 49c, 49c of the bearing box 49 and the like are set.

According to the supporting structure of the living knife holder 29 configured as described above, when assembling the living knife holder 29 to the bearing box 49 at the time of assembling the circular saw, as described above. By rotating the blade case 71 further upward than the position shown in FIG. 7, the live knife holder 29 is positioned at the “assembly position” with respect to the large diameter portion 49 b of the bearing box 49, and the “assembly” is performed. At the "position", the distal end of the link arm 40 is connected via the pin 40a. In this state, the large-diameter portion 49b is inserted into the support hole 29b to fit the riving knife holder 29 into the bearing box 49. Then, in this state, the blade case 71 is rotated downward to The three holes 29a, 71a, 2a may be aligned, and then the shaft portion 3a of the fixed lever 3 may be inserted into the three holes 29a, 71a, 2a in the above-described direction.

That is, when the blade case 71 is turned downward, the center of the spindle 60, the pins 40a, 40
The living knife holder 29 is relatively rotated upward, that is, clockwise, due to the four-node link structure including a total of four points including the center of the b and the center of the pin 41. Then, the protruding edges 29d and 29d formed in the support hole 29b and the distal end of the link arm 40 enter the arc groove 49d of the bearing box 49, and thereby the axis of the pin 40a of the living knife holder 29 and the link arm 40. The movement in the direction (ie, the axial direction of the spindle 60) is restricted. For this reason, the pin 40a inserted into the coupling hole 29e of the living knife holder 29 cannot be pulled out, whereby the assembly of the link arm 40 to the living knife holder 20 is completed.

According to the electric circular saw of this embodiment configured as described above, the following various effects can be obtained.

(1) A ruler mounting portion 1 is provided on the side of the base 12.
The mounting portion 13 has two thumb screws 13b, 13b. For this reason, since the parallel ruler is fixed by the two thumb screws 13b, 13b, it can be firmly fixed without rattling. Further, since the thumb screws 13b, 13b are provided near both front and rear ends of the groove portion 13a, the use of one of the thumb screws 13b allows the parallel ruler to be formed in comparison with the conventional configuration provided at one place. The base 12 can be fixed in a state of protruding in both front and rear directions, and the measurable range of the parallel ruler is widened.

(2) The grip 1 functions not only as a gripping portion for the operator to grip, but also as a fixing portion of the cutting angle adjusting mechanism of the saw blade 56, that is, as a member for tightening the thumb screw 4. Since it has a configuration having both components, it is possible to reduce the number of parts as compared with the case where the respective functions are conventionally achieved by separate members.

(3) Since the pin 41 for connecting the blade case 71 to the base 12 is a parallel pin, the pin 41 can be easily extracted without using a special tool when it is pulled out as in the case of using a spring pin. The pin 41 can be pulled out, and the pin 41 can be prevented from coming out of the hole 7c only by attaching the blade case cover 70 to the blade case 71. Therefore, no separate means such as a bolt or a snap ring is required for this removal. . From this, the mounting structure of the blade case 71 is simplified, and the number of parts of the circular saw is reduced or its assembling property and disassembly are improved.

Further, the blade case 71 is supported by the angular plate 7 with the front support edge 7d of the forked support portion 7a sandwiched between the overhanging edge 70b of the blade case cover 70. For this reason, even if the interval between the two supporting edges 7d and 7e of the forked support portion 7a is formed to be larger than the width of the supporting edge 71i of the blade case 71, the supporting edge 71i of the blade case 71 is located on the front side of the forked support portion 7a. Support edge 7
pressed against d. From this, both supporting edges 7d, 7
In addition, it is possible to support the blade case 71 on the angular plate 7, that is, the base 12 without looseness while securing the assembling property when inserting the supporting edge 71 i of the blade case 71 by relatively increasing the interval between e. it can.

In this embodiment, the fork supporting portion 7a is provided on the base 12 side to support the parallel pin 41 at both ends. For example, the supporting edge on the base 12 side is connected to the fork supporting portion 7a.
It is also possible to adopt a configuration in which the parallel pin 41 is cantilevered only as the support edge 7d on the front side. In this case, the hole formed on the supporting edge 71i of the blade case 71 is a bottomed hole.

In the embodiment described above, the support holes 7
Although c is formed in the bottomed hole so that the tip of the pin 41 protrudes from the side surface of the support edge 7d, the present invention is not limited to this, and may be configured as shown in FIG. That is,
As shown in the figure, both support edges 7d, 7e 'of the forked portion 7a' are provided.
Is formed through the support hole 7c '.
May be inserted with a pin 41 'with a collar.
According to this configuration, the flanged pin 41 'is inserted into the support hole 7c' with the flange 41a in contact with the left side surface of the support edge 7d in the drawing, and the flange 41a is inserted into the blade case cover. The overhanging edge 70b of 70 is pressed against the contact state. Therefore, according to this configuration, the blade case cover 70 is attached to the blade case 71 to prevent the pin 41 ′ with the flange from coming off, and the blade case 71 is attached to the angular plate 7.
That is, it is possible to support the base 12 without play. Note that this configuration can be applied to the above-mentioned cantilever support configuration.

(4) The conical portions 12b are provided on the opposing surfaces of the support edge 12b of the base 12 and the end 2e of the depth guide 2 supported by the support edge 12b via the pin 34.
e, 2c are formed, and the depth guide 2 is supported by the supporting edge 12b in a state where the two conical portions 12e, 2c are in contact with each other. For this reason, the draft guide 2 can be supported in a proper posture without inclining the depth guide 2 in the left-right direction while securing a draft when the base 12 is a die-cast component. Moreover, since the two conical portions 12e and 2c are brought into contact with each other in a state of contact with each other, the problem that occurs in the case of the conventional point contact does not occur, and the support edge 12b or the end 2e of the depth guide 2 is damaged. The depth guide 2 can be firmly fixed without receiving and without rattling.

(5) Since the fixing lever 3 and the hexagon nut 3e in the cutting depth adjusting mechanism of the saw blade 56 are fixed by the U-ring 3f, when a leaf spring or a fixing screw is used as in the conventional case, for example, In comparison, the structure of the circular saw can be simplified and its disassembly and assembly properties can be improved.

(6) The wind sucked into the motor housing 67 by the rotation of the fan 73
After being passed through 4, the air is blown out of the front of the fan 73, and then blown into the blade case 71 through the slits 71c to 71c. Here, conventionally, an outlet for discharging the wind sucked into the motor housing by the motor cooling fan is provided on, for example, a mating surface of the pedestal portion 71b and the motor housing 67 for blowing in a radial direction of the fan 73. The wind was blown out directly from the side of the mushroom, so when the wind was exhausted from the outlet, a wind noise was generated, and in some cases, the same state as blowing a whistle As a result, a very loud wind noise was generated, and the operator had to work while feeling uncomfortable, and the usability of the electric circular saw was significantly impaired. In this regard, as described above, according to the configuration of the present embodiment, the wind provided for cooling the motor
1, the wind noise is muffled in the blade case, so that the noise is greatly reduced as compared with the conventional configuration in which the noise is blown directly to the outside, and the quietness of the circular saw is enhanced. be able to.

Further, the pedestal portion 71b into which the wind blown in front of the fan 73 via the baffle plate 64 flows.
An inclined portion 71d having a smooth curved surface is formed at the bottom of the base 71. The inner peripheral wall surface 71h of the pedestal portion 71b has a smooth peripheral surface. For this reason, the wind blown forward of the fan 73 is guided smoothly toward the slits 71c to 71c without obstructing any flow and without generating abnormal noise (wind noise).
The wind reaching c to 71c hits partition walls 71e to 71e provided substantially orthogonal to the ventilation direction, and thereby the wind pressure in the ventilation path is appropriately increased. The wind blown back by appropriately increasing the wind pressure in the ventilation path is blown into the blade case 71 smoothly and dispersed through each slit 71c. From the above, the quietness of the marunoco can be enhanced.

Further, the air blown into the blade case 71 through the slits 71 c to 71 c is separated by the partition wall 82 a provided in the blade case 71.
Since the air is not blown into the inside of the blade case 71, there is no problem that the blowing efficiency is reduced by blowing the air into the blade case 71.

Although the noise prevention structure of the present embodiment has been described by taking a portable electric saw as an example, the noise prevention structure is not limited to a portable electric saw as described above. The present invention can be widely applied to an attached electric circular saw and the like.

(7) In the locking mechanism of the spindle 60, the compression coil spring 62 is housed in the recess 62a. Therefore, when assembling the compression coil spring 62, the operator lays down the compression coil spring 62 in the recess 62a. It only needs to be charged. That is, the compression coil spring 62
After being laid in the recess 62a, the locking plate 63 as a locking member moves the locking piece 63e between the front end of the compression coil spring 62 and the front wall (the left wall in the drawing) of the recess 62a. When inserted and supported so as to close the concave portion 62a, the compression coil spring 62
And the side supporting the lock plate 63, that is, the recess 6
2a is interposed between the pedestal 71b and the pedestal 71b, whereby the lock plate 63 is urged in a certain direction. This eliminates the necessity of screwing the coil spring as in the related art, so that anyone can easily perform the assembling work.

The lock plate 63 is attached to the pedestal 71
After the baffle plate 64 is inserted across the two groove portions 63b, 63b, the baffle plate 64 is arranged so as to cover the pedestal portion 71b with the protrusions 64a, 64a inserted into the two groove portions 63b, 63b. The mounting is completed by fixing the motor housing 67 to the base 71b, and the baffle plate 64 is also mounted in a predetermined state. For this reason, there is no need to individually support or fix the lock plate 63 and the baffle plate 64, and in this respect, the assemblability around the periphery is very good.

In the illustrated embodiment, the spindle 60
Is provided with a two-face width portion 60a to directly lock the rotation of the spindle 60. However, the present invention is not limited to this. For example, in the case of a small model, the spindle has a smaller diameter. In some cases, it is not appropriate to form a two-plane width portion in this case. In this case, for example, FIG.
As shown in FIG. 7, the output shaft 176a of the drive motor set to have a larger diameter than the spindle (not shown)
And the rotation of the spindle may be indirectly locked by locking the rotation of the output shaft 176a.

That is, the fan 73 attached to the output shaft 176a and the bearing 7 supporting the output shaft 176a
6b, a gap is provided through which the lock plate 163 can be inserted, and using this gap, the lock plate 163 is slidably supported via grooves 63b, 63b formed in the base 171b. The circular hole 163c and the circular hole 16
An engaging portion 163a including an engaging groove 163d formed continuously with 3c is provided. The circular hole 163c is
For the convenience of the assembling procedure of the bearing 6b, the bearing 76b is formed with a diameter that can be inserted, and the locking groove 163d is formed with a width larger than the width of the two-plane width portion 160a and smaller than the diameter of the output shaft 176a. ing. On the other hand, as shown in FIG.
63e is formed by cutting and raising downward, and a recess 162a similar to the above is provided at the bottom of the pedestal portion 171b.
The locking plate 163 is supported in a state where the locking piece 163e is inserted between the left end of the compression coil spring 162 in the drawing and the left side wall of the concave portion 162a.

According to the lock mechanism configured as described above, after the two-face width portion 160a of the output shaft 176a is oriented along the locking groove 163d as shown, the lock plate 163 is moved rightward in the drawing. By sliding, the two-face width portion 160a fits into the locking groove 163d, whereby the output shaft 176a is locked so as not to rotate. If the output shaft 176a is locked so as not to rotate, this output shaft 1
With the gear 76a, the spindle 60 that rotates integrally via the gear portion 76d and the driven gear 59 is locked so as not to rotate.

It is not necessary to individually support or fix the lock plate 163 and the baffle plate 64 by the same operation as described above, and the point that the assemblability around the lock mechanism is improved is the same.

In the above, the lock mechanism of the spindle in the electric circular saw has been described as an example. However, the lock mechanism is not limited to the electric circular saw, but can be widely applied to other rotary tools such as a disk grinder.

(8) The stopper rubber 37 serving as a stopper for restricting the rotation of the safety cover 50 in the counterclockwise direction is formed by inserting a cylindrical protrusion 38 on the inner peripheral side thereof and forming a part of the stopper rubber 37 into a cylindrical shape. Projection 38 and arc projection 3
9 and fixed by simply press-fitting. In this regard, since the fixing is conventionally performed by screws or the like, it is necessary to perform a screw tightening operation using a tool such as a screwdriver when mounting the stopper rubber, which is troublesome. However, according to the mounting structure of this embodiment, screws and the like are unnecessary, so that not only the number of parts can be reduced, but also the projections 38, 3
It is sufficient to press-fit between 9 parts, so that the assemblability is improved, and it can be easily removed even during disassembly and repair.

Here, as shown in FIG. 11 (b), the arc projection 39 can be an arc projection 139 having an inner peripheral surface formed in an uneven shape. That is, the groove 139 along the axial direction is formed on the inner peripheral surface of the arc projection 139.
a is formed at a plurality of locations at appropriate intervals in the circumferential direction. The cylindrical projection 38 and the stopper rubber 37 do not need to be changed.

According to the arc projection 139, the following operation and effect can be obtained. That is, when the blade case 71 is a cast product or a resin molded product, the inner peripheral surface of the arc projection 39 having no irregularities is the inner peripheral surface of the arc projection 39 as shown in FIG. As shown in (a), it is necessary to set a constant draft 39a, so that there is a problem that the holding force on the stopper rubber 37 is reduced and the stopper rubber 37 is easily pulled out. According to the arc projection 139 having the grooves 139a to 139a formed on the peripheral surface, if the groove 139a has a sufficient draft angle as shown in FIG. There is almost no need to set draft angles for 139b to 139b, and they can be formed substantially at right angles. From this, the stopper rubber 37
Is not reduced, and the stopper rubber 37 can be more firmly fixed because of the so-called spike action due to the unevenness of the inner peripheral surface serving as the contact surface.

Further, in the case of the arc projection 39, the contact surface against the stopper rubber 37 is large, so that there is a problem that the stopper rubber 37 is difficult to press-fit due to its resistance.
According to the arc projection 139, the total area of the contact surface 139b is smaller, so that there is an advantage that it is easy to press fit. In addition,
Although the area of the contact surface 139b is small, it is easy to press-fit it. However, the stopper rubber 37 is more firmly fixed by the spike action than in the case of the arc projection 39.

Furthermore, according to the mounting structure of the rubber stopper 37 of the above two embodiments, the stopper rubber 37 is formed by the cylindrical projection 38.
When the rotation of the safety cover 50 is stopped, the impact received when the rotation of the safety cover 50 is prevented is received by the projections 38, 38, or 139. Thus, the mounting strength of the rubber stopper 37 against an impact is improved as compared with the conventional screwing, and the durability thereof can be increased.

(9) The driving knife 30 is
8 can be fixed only by tightening one piece, so that the number of parts can be reduced and the operation of mounting the riving knife 30 can be simplified. Moreover, two protrusions 29c are provided in the long slot 30a.
Since 29c is inserted in a state where there is substantially no gap, it is possible to position this living knife 30 with respect to living knife holder 29 and fix it in a state without rattling.

(10) When the riving knife holder 29 is displaced from its "assembly position", the overhanging edge 29d of the riving knife holder 29 and the tip of the link arm 40 are both inserted into the arc groove 49d. The movement of the two members 29, 40 in the axial direction of the pin 40a is restricted, so that the link arm 4 cannot be released from the pin connection.
0 is mounted on the riving knife holder 29.

As described above, since the link arm 40 is securely pin-coupled without using a special means such as a rivet or a retaining ring as in the prior art, the work of attaching the link arm 40 is simplified, and the It is possible to improve the assemblability of the circular saw and reduce the number of parts.

Further, when the blade case 71 is rotated downward so that the shaft portion 3a of the fixed lever 3 is inserted, and the three holes 29a, 71a, and 2a are aligned, as described above, the link arm 40 Since the pin connection does not come off, there is no need for the operator to perform two operations such as inserting the shaft portion 3a with the other hand while preventing the pin connection from coming off with one hand. Also, the assemblability is improved.

[0103]

According to the first aspect of the present invention, no wind is blown to the side of the mushroom, so that no wind is blown to the worker, and thus the quietness of the mushroom is improved. In addition, the feeling of use is improved.

[0104]

[0105]

[Brief description of the drawings]

FIG. 1 is a right side view, partially broken away, of an embodiment of the present invention;

FIG. 2 is a partially cutaway left side view of the circular saw.

FIG. 3 is a partially cutaway plan view of a circular saw.

FIG. 4 is a vertical cross-sectional view of a circular saw.

FIG. 5 is a sectional view taken along line AA of FIG. 2;

FIG. 6 is a partially cutaway right side view of the circular saw at the time of the maximum cutting of the saw blade, showing a part of the blade case cover, the saw blade and the safety cover in a see-through manner.

FIG. 7 is a partially cutaway right side view of the saw blade at the time of the minimum cutting of the saw blade, showing a part of the blade case cover, the saw blade and the safety cover in a see-through manner.

FIG. 8 is a partially cutaway left side view of the mushroom, showing the entire depth guide with a handle portion partially shown in perspective.

FIG. 9 is a partially cutaway front view of the circular saw.

FIG. 10 is a front view showing another example of the support structure of the blade case.

FIG. 11 shows a mounting structure of a stopper rubber, and is a sectional view (a).
FIG. 7 is a sectional view taken along line BB of FIG. 6, and FIG. 6 (b) is a plan view showing another example thereof.

12A and 12B are diagrams showing a comparison of two types of arc projections. FIG. 12A is a longitudinal sectional view of an arc projection having no irregularities on the inner peripheral surface, and FIG. It is a longitudinal cross-sectional view of the Enako projection in which the unevenness was formed in FIG.

FIG. 13 is a cross-sectional view taken along line CC of FIG. 4, which is a plan view of a bottom surface of a pedestal portion of a blade case and a spindle lock mechanism.

FIG. 14 is a sectional view taken along line DD of FIG. 13;

15 is a sectional view taken along line EE of FIG.

FIG. 16 is a diagram showing another example of the spindle lock mechanism;
(a) is a plan view thereof, and (b) is a II-II of the (a).
It is a line sectional view.

FIG. 17 is a plan view showing a state in which the riving knife holder is attached to a bearing box.

FIG. 18 is a cross-sectional view taken along line FF of FIG. 6, and is a longitudinal cross-sectional view showing a state where the riving knife holder and the link arm are attached.

FIG. 19 shows the left supporting edge of the base. FIG. 19 (a) is a front view thereof, and FIG. 19 (b) is a sectional view taken along line GG of FIG. 19 (a).

FIG. 20 shows an end of the depth guide. FIG. 20 (a) is a front view thereof, and FIG. 20 (b) is a sectional view taken along line HH of FIG. 20 (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Grip 2 ... Depth guide 7 ... Angular plate 12 ... Base 13 ... Ruler mounting part 29 ... Living knife holder 37 ... Stopper rubber 38 ... Cylindrical projection, 39 ... Arc projection 40 ... Link arm 49 ... Bearing box 50 ... Safety cover 56 ... saw blade 60 ... spindle 63 ... lock plate 64 ... baffle plate 67 ... motor housing 71 ... blade case 71b ... pedestal, 71c ... slit, 71d ... inclined portion 71g ... rubber pin 73 ... fan 76a ... output shaft 82 ... dust collection Road 83 ... outlet

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Aritani Noda 3-11-8 Sumiyoshicho, Anjo-shi, Aichi Prefecture Makita Co., Ltd. (56) References JP-A-60-206601 (JP, A) Hei 3-79224 (JP, U) Japanese Utility Model Showa 57-90802 (JP, U) US Patent 2,999,995 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B27B 5/00-11 / 12

Claims (1)

(57) [Scope of request for utility model registration] 1. An electric circular saw having an output shaft of a drive motor and a centrifugal fan for cooling the drive motor,
A plurality of slits are formed in a wall portion closing the front in the ventilation direction on the leeward side of the centrifugal fan, and the wind generated by the centrifugal fan is blown into the blade case through the slits, and the slit is formed. all of the partition walls defining formed, set in a range that avoids site cutting debris generated by the cutting with the saw blade
Vignetting, and noise prevention structure characterized in that it is arranged radially.