JP2021041564A - Portable cutter - Google Patents

Abstract

To effectively prevent powder dust from being deposited onto a fixed cover.SOLUTION: A portable cutter (portable circular saw 1) comprises a fixed cover 50 for covering a part of a disk-like rotary blade tool (sawtooth 2); and a movable cover 60 for covering a part of the rotary blade tool 2, which is rotatably attached to the fixed cover 50. The movable cover 60 is designed to be able to be opened via rotation by storing at least the part inside the fixed cover 50. A plurality of through-holes 70 is formed in an outer peripheral area of the movable cover 60. The plurality of through-holes 70 is arranged in such a manner that a part or all of each through-hole 70 is located on an outer side in a radial direction than a blade edge of the rotary blade tool 2. Wind generated by rotation of the rotary blade tool 2 is designed to blow through the plurality of through-holes 70 toward the fixed cover 50, when at least a part of the movable cover 60 is stored inside the fixed cover 50.SELECTED DRAWING: Figure 7

Description

The present invention relates to a portable cutting machine.

Dust such as chips generated by cutting a processing object such as wood may accumulate on the inner surface of the fixed cover that covers the rotary cutting tool of the cutting machine. In the case of a cutting machine provided with a fixed cover and a movable cover that can be accommodated inside the fixed cover, dust easily enters between the two covers and easily accumulates on the inner surface of the fixed cover. As a countermeasure against such dust accumulation, for example, in the electric tool described in Japanese Patent Application Laid-Open No. 2012-81536, an outlet is provided in the fixed cover so that the cooling air of the motor is discharged into the fixed cover. ing. Further, a spiral guide wall is provided on the back surface of the movable cover to divert the cooling air along the guide wall to induce a rear wind and promote the discharge of dust to the rear.

Japanese Unexamined Patent Publication No. 2012-81536 Japanese Unexamined Patent Publication No. 08-238604

When the rotary cutting tool rotates, a wind (cutting wind) in the same direction as the rotation direction is generated around the rotary cutting tool. When the movable cover is opened only halfway and most of the inner surface of the fixed cover directly faces the rotary cutting tool, the cutting wind can blow dust backward to some extent. However, when the movable cover is sufficiently opened and the inner surface of the fixed cover is shielded by the movable cover, the space between the two covers (volume of space) is narrow and it is difficult for the cutting wind to enter. It cannot be fully utilized. Therefore, it is desired to effectively suppress the accumulation of dust on the fixed cover.

One aspect of the present invention is a portable cutting machine, which is a fixed cover that covers a part of a disk-shaped rotary cutting tool, and a movable cover that is rotatably attached to the fixed cover and covers a part of the rotating cutting tool. The movable cover is provided with a cover so that the movable cover can be opened by rotating at least a part thereof inside the fixed cover, and a plurality of through holes are formed in the movable cover, and the plurality of through holes are formed. The holes are arranged so that part or all of each through hole is located radially outward from the cutting edge of the rotary cutting tool, and when at least a part of the movable cover is housed inside the fixed cover, the rotary cutting tool The wind generated by the rotation blows through the plurality of through holes toward the fixed cover. As a result, the dust that has entered the movable cover reaches the fixed cover through the through hole and can be smoothly discharged backward. Even if the inner surface of the fixed cover is shielded by the movable cover, the cutting wind generated by the rotation of the rotary cutting tool blows through the through hole, so that it is possible to suppress the accumulation of dust on the inner surface of the fixed cover. In addition, dust flying with the cutting wind inside the movable cover is likely to be discharged to the outside of the movable cover through the through hole. Further, the decrease in rigidity can be suppressed by having a plurality of through holes instead of one large through hole.

In some embodiments, the plurality of through holes are arranged so as to be arranged along the circumferential direction of the movable cover. As a result, the cutting wind is less likely to be disturbed when passing through the through hole, so that dust can be efficiently discharged.

In some embodiments, the plurality of through holes are arranged in the peripheral wall portion of the movable cover. As a result, it is possible to suppress the accumulation of dust on the inner surface of the peripheral wall portion of the fixed cover.

In some embodiments, each through hole has a first width on the upstream side and a second width on the downstream side that is larger than the first width. As a result, the cutting wind spreads in the width direction on the downstream side of the through hole, so that the cutting wind can be blown inside the fixed cover over almost the entire width direction.

In some embodiments, each through hole has a slit portion and a wide portion on the downstream side of the slit portion. As a result, the cutting wind from the cutting tool can be partially rectified by the slit portion, so that the momentum of the cutting wind can be maintained, and as a result, dust can be effectively discharged.

In some embodiments, the wall surface on the downstream side of each through hole of the peripheral wall portion has an inclined surface that is inclined so as to open toward the fixed cover. As a result, the cutting wind blown in the same direction as the rotation of the saw blade easily passes through the through hole, and the dust can be effectively carried toward the rear discharge hole.

In some embodiments, the plurality of through holes are arranged on the side wall portion of the movable cover. As a result, it is possible to suppress the accumulation of dust on the inner surface of the side wall portion of the fixed cover.

In some embodiments, the wall surface on the downstream side of each through hole of the side wall portion has an inclined surface inclined so as to open toward the fixed cover. As a result, the cutting wind blown in the same direction as the rotation of the saw blade easily passes through the through hole, and the dust can be effectively carried toward the rear discharge hole.

Depending on the embodiment, a part of the plurality of through holes is arranged on the peripheral wall portion of the movable cover, and the other part is arranged on the side wall portion of the movable cover. As a result, it is possible to suppress the accumulation of dust on the inner surfaces of both the peripheral wall portion and the side wall portion of the fixed cover.

In some embodiments, a discharge hole for discharging dust is formed at the rear portion of the fixed cover, an inlet of the discharge hole is opened on the inner surface of the fixed cover, and the movable cover is placed on the upper surface of the material to be cut. At the time of abutting, at least one of the plurality of through holes comes to the upstream side of the inlet of the discharge hole of the fixed cover. As a result, the dust can be guided to the discharge hole by the cutting wind that has blown through the through hole.

It is a right side view of the portable circular saw as the first embodiment. It is a front view of the portable circular saw of FIG. It is sectional drawing which shows the portable circular saw of FIG. 2 cut by the plane (line III-III) of the saw blade. It is a perspective view which looked at the lower left side of the portable circular saw of FIG. 1 from the rear. It is sectional drawing which cut the portable circular saw of FIG. 1 by the VV line of FIG. 7, and is shown in the electric motor, the reduction gear part, the gap between the fixed cover and the movable cover when the movable cover is opened, and the movable cover. It shows the provided through hole. It is sectional drawing which cut at the part of the dust discharge hole provided in the rear part of a fixed cover, and was seen from the rear side slightly above. It is a cross-sectional view of the right side which shows the portable circular saw when the movable cover is opened with the maximum depth of cut cut by the plane of the saw blade. It is a cross-sectional view of the right side which shows the portable circular saw when the movable cover is opened by reducing the depth of cut by cutting with the plane of the saw blade. It is a side view which looked at the movable cover as 1st Embodiment from the front side. It is a side view which looked at the movable cover of FIG. 9 from the back side. FIG. 10 is a cross-sectional view of the movable cover of FIG. 10 cut along the XI-XI line and viewed from the inside. It is a side view which looked at the movable cover as a 2nd Embodiment from the back side. It is sectional drawing which cut the movable cover of FIG. 12 by line XIII-XIII. It is a side view which looked at the movable cover as 3rd Embodiment from the back side. It is sectional drawing which cut the movable cover of FIG. 14 by XV-XV line. It is the figure which looked at the slit of the peripheral wall surface of the movable cover of another form from the outside. 16 is a cross-sectional view of the movable cover of FIG. 16 cut along the line XVII-XVII.

Next, various embodiments of the present invention will be described with reference to the drawings. Components that are common or correspond to a plurality of embodiments are designated by the same reference numerals, and the description thereof will not be repeated.
[Portable cutting machine]
1 to 8 show a portable circular saw 1 as an embodiment of the present invention. The portable circular saw 1 includes a main body portion 10 and a base 3 that supports the main body portion 10. A disk-shaped saw blade 2 which is a cutting tool can be attached to and detached from the main body 10, and the saw blade 2 rotates using an electric motor 20 built in the main body 10 as a drive source. A window portion 3a (FIG. 4) penetrating in the vertical direction is opened in the base 3, and the lower side of the saw blade 2 is projected to the lower side of the base 3 through the window portion 3a. When cutting the material W to be cut, the user pushes the portable circular saw while pressing the base 3 against the upper surface of the material W to be cut, and cuts the saw blade 2 protruding downward from the base 3 into the material W to be cut from the front. Let it get crowded.

In the following, as one embodiment, a portable circular saw, which is a kind of portable cutting machine which is an electric tool for cutting processing that can be carried by an operator, will be described. The portable cutting machine also includes, for example, a cutter with a diamond wheel attached. The portable circular saw 1 is provided with a disk-shaped saw blade 2 as a cutting tool as described above, but as another embodiment, a cutter other than the saw blade 2 such as a cutter with a diamond wheel is used. Can be applied with the same structure and features as those described below.

As shown in FIGS. 1 and 2, a loop-shaped handle 40 gripped by the user is provided at the rear portion of the main body portion 10 so as to project further rearward from the rear end edge of the base 3. A trigger type switch lever 42 is provided on the upper part of the handle 40. When the switch lever 42 is pulled with the fingertip of the hand holding the handle 40, the electric motor 20 is activated and the saw blade 2 is rotated. When performing the cutting process, the user can stand behind the portable circular saw 1 and move the portable circular saw 1 forward while grasping the handle 40 with his right hand. In the terms related to the front, back, left and right of the components of the portable circular saw 1 used in the following description, the direction in which cutting proceeds is defined as the front side (back side), and the side on which the user stands is defined as the rear side (front side).

[Cut adjustment mechanism]
A support portion 4 is provided on the upper side of the front portion of the base 3, and the main body portion 10 can swing up and down with respect to the support portion 4 via the swing support shaft 12 (at the front portion of the fixed cover 50 described later). Be supported. By swinging the main body 10 up and down around the swing support shaft 12, the amount of protrusion of the saw blade 2 downward from the base 3 is changed, and the cutting depth of the saw blade 2 with respect to the material W to be cut is increased. Can be adjusted. Another support portion 6 is provided on the upper rear side of the base 3, and the main body portion 10 is supported so as to be tiltable to the left and right with respect to the base 3 via tilting support shafts provided on the front and rear support portions 4 and 6, respectively. Will be done. By tilting the main body 10 to the left and right around the tilting support shaft, the cutting angle of the saw blade 2 with respect to the material W to be cut can be adjusted.

[Electric motor]
As shown in FIG. 5, the main body 10 includes the electric motor 20. The electric motor 20 is arranged in a posture in which the rotation axis is oriented in the left-right direction. The electric motor 20 includes a cylindrical stator 22, a rotor 23 rotatably supported inside the stator 22, and a motor shaft 24 that outputs rotational power integrally with the rotor 23. The motor shaft 24 is rotatably supported by bearings fixed to the main body housing at both ends.

The spindle 17 to which the saw blade 2 is attached is arranged parallel to the motor shaft 24 and is rotatably supported by a bearing fixed to the main body housing. A reduction gear portion 15 for decelerating the rotation of the electric motor 20 is provided between the electric motor 20 and the spindle 17. The reduction gear portion 15 is, for example, a two-stage reduction mechanism including an intermediate shaft 16.

The tip of the spindle 17 is projected into the fixed cover 50, and the saw blade 2 is attached to the protrusion of the spindle 17. The saw blade 2 is sandwiched between the outer flange 2a and the inner flange 2d (FIG. 5). The saw blade 2 is sandwiched by tightening the fixing bolt 2c on the tip surface of the spindle 17, and is fixed to the spindle 17 so as not to rotate.

[Battery mounting part]
As shown in FIG. 4, a battery mounting portion 30 for mounting a battery pack 31 that serves as a power source for the portable circular saw 1 is provided on the rear side of the electric motor 20. The battery mounting portion 30 is such that the battery pack 31 can be mounted on the lower surface thereof, for example. The battery pack 31 is, for example, a lithium ion battery that can be used repeatedly by charging. Further, as another embodiment, instead of providing the battery mounting portion 30, an electric tool using a commercial power source of AC 100V can be used.

[Fixed cover]
As shown in FIGS. 1 to 3, the main body 10 includes a metal fixing cover 50 that covers a region substantially half of the upper side of the saw blade 2. The fixed cover 50 is generally semicircular. The fixed cover 50 includes a peripheral wall portion 51 that covers the extension of the flat surface of the saw blade 2, a side wall portion 52 that covers the front side (opposite side of the motor) of the cutting edge 2b, and a back side (motor side) that is integrally connected to the main body housing. It has a side wall portion 53. The side wall portion 52 on the front side extends radially inward from the peripheral wall portion 51 on the front side of the saw blade 2. The fixed cover 50 is formed integrally with the gear housing accommodating the reduction gear portion 15 with metal. An arrow 52a indicating the rotation direction of the saw blade 2 is attached to the side wall portion 52 on the front side of the fixed cover 50.

[Dust discharge hole]
As shown in FIG. 6, the fixed cover 50 is provided with a dust discharge hole 55. The dust discharge hole 55 communicates from the inlet that opens on the inner surface of the peripheral wall portion 51 of the fixed cover 50 to the outlet that opens on the side surface (right side) of the fixed cover 50 while curving. Dust such as chips blown upward from the material W to be cut by the rotation of the saw blade 2 is carried backward by the wind (cutting wind) generated by the rotation of the saw blade 2 and is flowed backward in the fixed cover 50. It is discharged to the outside through the dust discharge hole 55. A dust collection bag or a dust collection hose can be attached to the outlet of the dust discharge hole 55. The dust that has flowed to the rear part in the fixed cover 50 by the cutting wind is collected in the dust collection bag attached to the dust discharge hole 55. Alternatively, the dust is forcibly sucked by the dust collector through the dust collection hose connected to the dust discharge hole 55.

[Movable cover]
As shown in FIGS. 1 to 3, a movable cover 60 capable of covering a region substantially half of the lower side of the saw blade 2 is attached to the main body 10. The movable cover can be made of resin. The movable cover 60 is supported so as to be rotatable around the center of the saw blade 2, and can be opened and closed by rotation. When viewed from the right side as shown in FIGS. 1 and 3, the opening direction is clockwise and the closing direction is counterclockwise. The movable cover 60 generally includes a peripheral wall portion 61 that covers an extension of the plane of the saw blade 2, a side wall portion 62 that covers the front side (opposite side of the motor) of the saw blade 2, and a side wall portion 63 that covers the back side (motor side). Has. The side wall portion 63 on the back side extends from the peripheral wall portion 61 to the boss portion 63a having a columnar inner peripheral surface. The side wall portion 62 on the front side extends radially inward from the peripheral wall portion 61 so as to cover the cutting edge 2b of the saw blade 2, but does not extend as much as the side wall portion on the back side. The movable cover 60 is rotatably supported around the same axis as the rotation axis of the spindle 17 and the saw blade 2. Specifically, as shown in FIG. 5, the bearing that supports the end of the spindle 17 on the saw blade side is held by the bearing holding portion 15a of the main body housing. The side wall portion 63 on the back side of the movable cover 60 has a boss portion 63a having a columnar inner peripheral surface, and the movable cover 60 can rotate to the columnar outer peripheral surface of the bearing holding portion 15a via the boss portion 63a. Attached to. The movable cover 60 is urged in the closing direction by a spring (not shown) and covers a range of approximately half the lower side of the saw blade 2 when not cut. When the movable cover 60 is opened against the urging by the spring, it enters the gap between the saw blade 2 and the fixed cover 50.

[Movement of movable cover when cutting]
As shown in FIG. 3, when cutting the material W to be cut with the saw blade 2 while applying the base 3 to the upper surface of the material W to be cut during cutting, the movable cover 60 is pushed to the front edge of the material W to be cut. And rotate in the opening direction. When the material W to be cut is further cut, the movable cover 60 further rotates in the opening direction and rides on the upper surface of the material W to be cut. As shown in FIG. 7, the position when the movable cover 60 completely rides on the upper surface of the material W to be cut is the opening position of the movable cover 60. The opening position of the movable cover 60 with respect to the fixed cover 50 and the opening amount (relative rotation angle from the closed position) at that position differ depending on the set cutting depth. For example, when the depth of cut is maximum as shown in FIG. 7, the movable cover 60 rotates nearly half a circumference until it completely rides on the material W to be cut. On the other hand, when the cutting depth is shallow as shown in FIG. 8, since the fixed cover 50 is lifted from the base 3 together with the saw blade 2, the opening amount of the movable cover 60 with respect to the fixed cover 50 is small. The movable cover 60 can be manually opened to the fully open position. However, the opening position when the material W is automatically opened by riding on the material W to be cut does not always reach this fully opened position.

[Through hole]
As shown in FIGS. 4 and 9 to 11, a plurality of through holes 70 are formed in the movable cover 60. As a first embodiment, as shown in the figure, these through holes 70 are provided in the peripheral wall portion 61 of the movable cover 60. Although the figure shows three through holes 70, the number of through holes 70 is not limited as long as there are a plurality of through holes 70. When at least a part of the movable cover 60 enters the inside of the fixed cover 50, the cutting wind generated by the rotation of the saw blade 2 blows through the plurality of through holes 70 toward the fixed cover 50. As shown in FIG. 3, when the opening amount of the movable cover 60 is still small, such as immediately after the start of cutting, the cutting wind easily blows directly onto the inner surface of the peripheral wall portion 51 of the fixed cover 50, so that dust is unlikely to accumulate on the fixed cover 50. As shown in FIG. 7, when the cutting progresses and the opening amount of the movable cover 60 becomes large, the inner surface of the fixed cover 50 is gradually shielded by the movable cover 60, but even in this case, the cutting wind blows through the through hole 70, so that dust is present. It is possible to suppress the deposition of. Further, dust that flies with the cutting wind inside the movable cover 60 is also easily discharged to the outside of the movable cover 60 through the through hole 70.

As shown in FIGS. 7 and 8, in the plurality of through holes 70, at least one through hole 70 is a fixed cover when the movable cover 60 abuts on the upper surface of the material W to be cut by cutting the material W to be cut. It is arranged at a position so as to come upstream from the entrance of the dust discharge hole 55 of 50. For example, as shown in the figure, all the through holes 70 are made to be on the upstream side of the entrance of the dust discharge hole 55 regardless of whether the cutting depth is maximized or shallow. However, as another embodiment, when the cutting depth is made shallow, only a part of the through holes 70 may be arranged to be upstream of the entrance of the dust discharge hole 55. The upstream referred to here means the upstream of the cutting wind that blows in the same direction as the rotation of the saw blade 2, as shown by the arrows in FIGS. 7 and 8. When the movable cover 60 is in the open position as shown in the figure, the front side of the portable circular saw 1 is generally upstream and the rear side is downstream. As described above, since at least one through hole 70 is on the upstream side of the dust discharge hole 55, the dust can be guided to the dust discharge hole 55 by the cutting wind that has blown through the through hole 70.

As shown in FIGS. 4 and 11, the width (dimension in the rotation axis direction) of each through hole 70 is the first width on the upstream side and the second width larger than the first width on the downstream side. .. Specifically, each through hole 70 has a slit portion 71 having a constant width and a wide portion 72 located downstream of the slit portion 71 and having a width larger than that of the slit portion 71. Although not shown, as another embodiment, a triangular through hole 70 whose width gradually increases from the upstream side to the downstream side may be used.

As shown in FIGS. 4, 9, and 10, each through hole 70 is an inclined surface 72a in which the wall surface on the downstream side of the wide portion 72 is open outward in the radial direction. In other words, the inclined surface 72a is inclined toward the downstream direction toward the outer side in the radial direction. On the other hand, the wall surface on the upstream side of the wide portion 72 is also inclined, but the inclination angle is not as large as that on the downstream side. The slit portion 71 is open to the wall surface on the upstream side of the wide portion 72 at the downstream end. Since the wall surface on the downstream side of the wide portion 72 is an inclined surface 72a, the cutting wind blown in the same direction as the rotation of the saw blade 2 easily passes through the through hole 70, and the dust is directed toward the dust discharge hole 55 behind. Effectively easy to carry.

[Other Embodiments]
As a second embodiment, as shown in FIGS. 12 and 13, a through hole 80 may be provided in the side wall portion 63 on the back side of the movable cover 60. Also in this case, as in the first embodiment, the through hole 80 is arranged in the outer peripheral region of the movable cover 60. For example, the through hole 80 is arranged at a position facing the cutting edge 2b of the saw blade 2. Alternatively, the plurality of through holes 80 are arranged so that a part or all of the through holes 80 are located radially outside the cutting edge 2b of the saw blade 2. Although the figure shows four through holes 80, the number of through holes 80 is not limited as long as there are a plurality of through holes 80. Further, as in the first embodiment, the through holes 80 are arranged so as to be arranged along the circumferential direction of the movable cover 60. Instead of arranging them on the circumference as shown in the figure, as another embodiment, they may be arranged in a zigzag or irregular manner (while changing the distance from the center of rotation for each through hole 80) along the circumferential direction. .. The plurality of through holes 80 are positioned so that at least one through hole 80 comes to the upstream side of the entrance of the dust discharge hole 55 of the fixed cover 50 when the movable cover 60 is brought into contact with the upper surface of the material to be cut. Be placed. Each through hole 80 is an inclined surface 80a whose downstream wall surface opens toward the outside (fixed cover side). In other words, the inclined surface 80a is inclined toward the downstream side toward the outside. On the other hand, the wall surface on the upstream side is not inclined and is a surface perpendicular to the outer surface of the side wall portion 63. According to this second embodiment, when the opening amount of the movable cover 60 becomes large and the inner surface of the fixed cover 50 is shielded by the movable cover 60, the cutting wind blows through the through hole 80 and reaches the inner surface of the side wall portion 53. It is possible to spray. In particular, as can be seen from the figure, the side wall portion 53 on the back side of the fixed cover 50 has many undulations due to the presence of a mechanism such as a reduction gear portion, and dust is likely to accumulate on the side wall portion 53 on the back side of the movable cover 60. The through hole 80 provided in 63 is effective. As another embodiment, a plurality of through holes similar to those described above may be provided not in the side wall portion 63 on the back side of the movable cover 60 but in the side wall portion 62 on the front side. In this case, dust accumulation on the inner surface of the side wall portion 52 on the front side of the fixed cover 50 can be suppressed.

As a third embodiment, as shown in FIGS. 14 and 15, through holes 70 and 80 may be provided in the peripheral wall portion 61 of the movable cover 60 and the side wall portion 63 on the back side, respectively. In this case, the through hole 70 of the peripheral wall portion 61 can be the same as the through hole 70 of the first embodiment described above, and the through hole 80 of the side wall portion can be the same as the through hole 80 of the second embodiment.

As yet another form, as shown in FIGS. 16 and 17, one through hole 90 may be provided in the peripheral wall portion 61 of the movable cover 60. The movable cover 60 is made of resin. The through hole 90 can be a slit extending along the circumferential direction. By preventing the slit from reaching the end of the peripheral wall, it is possible to minimize a decrease in the rigidity of the movable cover 60. However, in order to further suppress the decrease in rigidity, it is preferable to provide a plurality of smaller through holes 60, 70 as in the first to third embodiments instead of this one slit.

Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to these embodiments, and those skilled in the art can perform various substitutions without deviating from the object of the present invention. It is possible to make improvements and changes.

W Material to be cut 1 Portable circular saw 2 Saw blade 2a Outer flange 2d Inner flange 2c Fixing bolt 2b Cutting edge 3 Base 3a Window 4 and 6 Support 10 Main body 12 Swing support shaft 15 Reduction gear 16 Intermediate shaft 17 Spindle 20 Electric motor 22 Stator 23 Rotor 24 Motor shaft 30 Battery mounting part 31 Battery pack 40 Handle 42 Switch lever 50 Fixed cover 51 Peripheral wall part 52 Front side wall part 53 Back side wall part 60 Movable cover 61 Peripheral wall part 62 Front side wall part 63 Back side wall 63a Boss 70 Through hole 71 Slit 72 Wide 72a Inclined surface 80 Through hole 80a Inclined surface 90 Through hole

Claims (10)

It ’s a portable cutting machine,
A fixed cover that covers a part of the disk-shaped rotary cutting tool,
It is provided with a movable cover that is rotatably attached to the fixed cover and covers a part of the rotary cutting tool.
The movable cover can be opened by rotating so that at least a part thereof is housed inside the fixed cover.
A plurality of through holes are formed in the movable cover, and the plurality of through holes are arranged so that a part or all of the through holes are located radially outside the cutting edge of the rotary cutting tool. A portable cutting machine in which, when at least a part thereof is housed inside the fixed cover, the wind generated by the rotation of the rotary cutting tool blows through the plurality of through holes toward the fixed cover. The portable cutting machine according to claim 1, wherein the plurality of through holes are arranged so as to be arranged along the circumferential direction of the movable cover. The portable cutting machine according to claim 1 or 2, wherein the plurality of through holes are arranged on the peripheral wall portion of the movable cover. The portable cutting machine according to claim 3, wherein each through hole has a first width on the upstream side and a second width larger than the first width on the downstream side. For cutting machine. The portable cutting machine according to claim 4, wherein each through hole has a slit portion and a wide portion on the downstream side of the slit portion. A portable cutting machine according to any one of claims 3 to 5, wherein the wall surface on the downstream side of each through hole of the peripheral wall portion has an inclined surface inclined so as to open toward the fixed cover. The portable cutting machine according to claim 1 or 2, wherein the plurality of through holes are arranged on the side wall portion of the movable cover. The portable cutting machine according to claim 7, wherein the wall surface on the downstream side of each through hole of the side wall portion has an inclined surface inclined so as to open toward the fixed cover. In the portable cutting machine according to claim 1 or 2, a part of the plurality of through holes is arranged on the peripheral wall portion of the movable cover, and the other part is arranged on the side wall portion of the movable cover. A portable cutting machine. In the portable cutting machine according to any one of claims 1 to 9, a discharge hole for discharging dust is formed at the rear portion of the fixed cover, and an inlet of the discharge hole opens on the inner surface of the fixed cover. Cover,
A portable cutting machine in which at least one of the plurality of through holes comes to the upstream side of the inlet of the discharge hole of the fixed cover when the movable cover is brought into contact with the upper surface of the material to be cut.

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