Patent Application
20210362252
The present disclosure relates to a portable circular saw for cutting metal by holding and moving the portable circular saw by hand.
For example, in a portable circular saw (portable cutting device) for cutting metal, which is referred to as a tip saw cutter in which a chip saw is used for cutting metal, various countermeasures are taken. For example, countermeasures are taken for effectively catching sparks that are generated when cutting work is performed and also catching cutting dust produced while the sparks are solidified. A dust collection structure related to these kind of circular saws is disclosed in the following Patent Document 1 and Patent Document 2.
Patent Document 1 (Japanese Laid-Open Patent Publication No. 2005-138220) discloses a technique in which cutting dust generated at a cutting position is blown up with a flow generated by rotation of a circular saw blade (chip saw), such that cutting dust is collected in a cutting dust collection box. Patent Document 2 (Japanese Laid-Open Patent Publication No. 2012-030356) discloses a technique in which an inner wall of a fixing cover, which covers a periphery of a circular saw blade, is curved. This allows the cutting dust to be blown out to the curved inner wall so as to control a scattering direction of cutting dust, thereby improving the efficiency for collecting cutting dust in the cutting dust collection box. A tip saw is a kind of circular saw blade that is obtained by integrally welding a tip to a base metal, both of which are manufactured as separate members.
However, according to the prior art disclosed in the former Patent Document 1, because a front of the fixing cover is too large, the effect of the rotating flow to blow up the generated cutting dust is not sufficiently exhibited. Thus, cutting dust may not be efficiently flown deep into the cutting dust collection box. In this respect, collection efficiency into the cutting dust collection box is not sufficient. Furthermore, according to the prior art disclosed in the latter Patent Document 2, a large leakage of the collected cutting dust occurs (a large quantity of cutting dust flows out of a dust collection opening) because an entrance of the cutting dust collection box (dust collection opening) is too small. In this respect, collection efficiency is not sufficient. There are specific features when cutting metal, cutting dust of metal is heavier than that of wood. Accordingly, the cutting dust of metal easily flows in a radial direction, owing to a stronger centrifugal force acted thereon. Additionally, fewer metal cuttings flow in the air, which is strongly influenced by rotation power of the circular saw blade. There is no prior art in which these features are fully analyzed and optimized.
The present disclosure aims to further improve collection efficiency of the cutting dust generated by the portable circular saw for cutting metal.
The above described problems can be solved by using at least the following aspects. A first aspect is a portable circular saw for cutting metal that comprises a base having a lower surface which contacts a cutting material and a cutting device main body supported on an upper surface of the base. Also, the cutting device main body comprises a circular saw blade, a fixing cover that covers the circular saw blade, and a cutting dust collection box that collects cutting dust generated when metal is cut. Cutting is performed by protruding the circular saw blade from the lower surface of the base via a window provided in the base. A protruding portion of the circular saw blade cuts into the cutting material. In the first aspect, at a lower end of the fixing cover, a distance X1 between an inner wall surface of the fixing cover and a tooth tip of the circular saw blade is set longer than a distance T between the tooth tip and a tooth bottom of the circular saw blade and shorter than twice as long as such distance T. In this document, the circular saw blade includes both of a tip saw and a circular saw blade other than the tip saw. The tooth tip means an outermost end of the saw blade and the tooth bottom means an innermost end of the tooth of the saw blade. The tooth means a notch formed along an outer circumference of the circular saw blade. In a case of the chip saw, the tooth is formed by a tip and a portion of the base metal.
According to the first aspect, at the lower end of the fixing cover relating to a position in an up-to-down direction, the distance X1 between the inner wall surface of the fixing cover and the tooth tip is set longer than the distance T between the tooth tip and the tooth bottom and shorter than twice as long as such distance T (the distance T<the distance X1<the distance T×2). Because the distance X1 is set longer than the distance T, when the metal cutting dust that has accumulated in the tooth bottom (cutting dust accumulated within a length of the distance T) is emitted outside in a radial direction of the circular saw blade, owing to a centrifugal force, the emitted cutting dust may be smoothly emitted to a gap (space) between the tooth tip and an inner wall of the fixing cover. It is emitted such that the cutting dust is not blocked by the inner wall surface of the fixing cover, which may improve dust collection efficiency. Also, because the distance X1 is set shorter than twice as long as the distance T, the device may avoid an effect that is caused by a phenomenon that a flow speed is rapidly reduced at a position exceeding twice as long as the distance T in the radial direction. Because of this, emitted cutting dust can efficiently be collected within the cutting dust collection box due to the rotational flow.
The second aspect, which relates to the portable circular saw according to the first aspect, is characterized in that a distance Y between a front end of the window in the base and the tooth tip of the circular saw blade is set longer than the distance T between the tooth tip and the tooth bottom and shorter than twice as long as this distance T.
According to the second aspect, cutting dust flowing to the tooth bottom may be emitted to a gap (the distance Y) between the tooth tip and the front end of the window in the base and be collected within the fixing cover. Also, because the distance Y is set twice as long as the distance T, the rotational flow can fully act on the emitted cutting dust, so as to allow the emitted cutting dust to flow along the inner wall surface of the fixing cover in a reliable manner. In this respect, dust collection efficiency of the fixing cover can be further improved.
The third aspect, which relates to the portable circular saw according to the first aspect or the second aspect, is characterized in that a distance X2 between the inner wall surface of the fixing cover and the tooth tip of the circular saw blade at a height of a rotational center of the circular saw blade relating to a position in an up-to-down direction is set longer than the distance T and shorter than twice as long as this distance T.
According to the third aspect, at the height of the rotational center of the circular saw blade relating to the position in the up-to-down direction, the distance X2 between the inner wall surface of the fixing cover and the tooth tip of the circular saw blade may be set similar to the distance X1. Because of this configuration, cutting dust can be smoothly emitted into a gap (the distance X1) between the tooth tip and the inner wall surface, and the cutting dust can efficiently flow to the fixing cover due to the rotational flow.
The fourth aspect, which relates to the portable circular saw according to any one of the first aspect to the third aspect, is characterized in that the distance X1 is set longer than the distance Y between the front end of the window in the base and the tooth tip of the circular saw blade.
According to the fourth aspect, during a time when the tooth tip of the rotating circular saw blade enters into the fixing cover through the window in the base, cutting dust can be smoothly emitted from the tooth bottom, thereby improving dust collection efficiency.
The fifth aspect, which relates to the portable circular saw according to any one of the first aspect to the fourth aspect, is characterized in that a dust collection path into the cutting dust collection box is defined and arranged along and around the circular saw blade. A guide member is provided in a dust collection opening located at an inflow side end of the dust collection path in order to guide cutting dust to a side of the dust collection opening.
According to the fifth aspect, the guide member can improve dust collection efficiency into the dust collection opening.
The sixth aspect, which relates to the portable circular saw according to the fifth aspect, is characterized in that the guide member is arranged is a tilting manner, such that an outside of the guide member in a radial direction of the circular saw blade is displaced toward a front side in a rotational direction of the circular saw blade. The guide member has a fork shape extending on both sides, in a thickness direction, of the circular saw blade.
According to the sixth aspect, the guide member can further improve dust collection efficiency into the dust collection opening.
Next, embodiments according to the present aspect will be explained with reference to
The cutting device main body 20 comprises an electric motor 21 as a drive source, a circular saw blade 22, and a loop-shaped handle 23. A brushless motor, which is high-powered and compact in a motor axis direction, is used as the electric motor 21. A tip saw blade for cutting steel material is used as the circular saw blade 22. As shown in
As shown in
The fixing cover 24 is fixed to the cutting dust collection box 25 using a fixing screw 27 and is attached to the cutting device main body 20. The fixing cover 24 can be detached from around the circular saw blade 22 by loosening the fixing screw 27. An arrow 28 indicating a rotational direction of the circular saw blade 22 is marked on a right side surface of the cutting dust collection box 25. As shown in
A lower portion side of the circular saw blade 22 protrudes from a lower surface side of the base 10 and through a long-groove-shaped window 11 formed in the base 10. Cutting is executed by this protruding portion cutting into the cutting material W. The tooth tips located at the lower portion side of the circular saw blade 22 that protrudes from the lower surface side of the base 10 are covered with a movable cover 30. The movable cover 30 is configured to rotate approximately around a rotational center of the circular saw blade 22, such that the tooth tips 22a can be exposed and covered. The movable cover 30 relatively opens in accordance with the movement of the tip saw cutter in a cutting/advancing direction while the movable cover 30 is in contact with the cutting material W. As shown in
As shown in
The loop-shaped handle 23 is formed above the speed reduction gear 31. A trigger-typed switch lever 23d is provided on an inner peripheral side of the handle 23. When the switch lever 23d is pulled upwards, for example, by a finger, a main switch (not shown in the figures) housed in the handle 23 is turned on. When the main switch is turned on, the electric motor 21 is activated. When the pulling operation of the switch lever 23d is released, the main switch is turned off and the electric motor 21 stops.
A front portion 23a of the handle 23 is connected to an upper portion of the gear housing 31a. The front portion 23a of the handle 23 rises upwards from the upper portion of the gear housing 31a. A grip 23b extends from an upper of the front portion 23a in an obliquely downward and rearward direction. A strap connection portion 23a for connecting a fall-prevention tether strap, etc. is formed in a rear portion of the grip 23b. A rear side portion of the grip 23b is connected to a rear surface side of the gear housing 31a via a battery attachment portion 35. A battery pack 36 is attached to a lower surface side of the battery attachment portion 35.
The electric motor 21 is powered by the battery pack 36 attached to the battery attachment portion 35. The battery pack 36 can be detached from the battery attachment portion 35 to allow for charging. Thus, the battery pack 36 can be repeatedly used. As shown by a void arrow in
A controller housing 37 is provided between the electric motor 21 and the battery attachment portion 35. The controller housing 37 houses a rectangular plate shaped controller in which a controller circuit board mainly for controlling the electric motor 21 is included.
An illumination device 38 is provided in front of the speed reduction gear 31 and at a lower of the front portion 23a of the handle 23. The cutting position C (cutting position of the circular saw blade 22 with respect to the cutting material W) can be brightly illuminated by the illumination device 38. Because of this, cutting work in a dark place, etc. can be conveniently executed.
A rotation output of the electric motor 21 is transmitted to an output shaft 39 via the speed reduction gear 31. The output shaft 39 enters into an inner side of the fixing cover 24. The circular saw blade 22 is attached to a right end portion of the output shaft 39, the portion in the fixing cover 24. As shown in
As shown in
As shown in
In the present embodiment, the distance X1, the distance X2, and the distance Y are properly set with regard to the distance T. In the present embodiment, in a state where a cutting depth is set to the maximum, the distance X1 defined at the lower end of the fixing cover 24 is set to 1.8 times as long as the distance T, the distance from the tooth bottom 22b to the tooth tip 22a (X1=1.8T). Also, the distance X2, which is measured at the height H from the upper surface of the base 10 where the rotational center of the circular saw blade 22 is located (at the height where a distance X becomes the shortest and slightly above the cutting position C), is set to 1.7 times as long as the distance T, the distance from the tooth bottom 22b to the tooth tip 22a (X2=1.7T). Both the distance X1 and the distance X2 may be modified within a range longer than the distance T and shorter than twice as long as the distance T (the distance T<the distance X1, the distance X2<the distance T×2). It is not necessary that the distance X1 be precisely the same as the distance X2. The distance X1 may be different from the distance X2, as long as they are both set within the above described range. Also, the distance Y is set to 1.5 times as long as the distance T in this embodiment. However, the distance Y may be modified within a range that is longer than the distance T and shorter than twice as long as the distance T (the distance T<the distance Y<the distance T×2).
In this way, positions of the front end 11a of the window 11 and the inner wall surface 24a of the fixing cover 14 with regard to the tooth tip 22a are set to the distances X1, X2, and Y in a necessary and sufficient manner. Because of this configuration, cutting dust temporarily stored in the groove of the circular saw blade 22 may smoothly pass through the front end 11a of the window 11 and be emitted into the fixing cover 24.
Furthermore, the distance X1 and the distance Y are properly set such that the lower end of the fixing cover 24 does not cover the front end 11a of the window 11 in the base 10 (the distance X1>the distance Y). Because of this configuration, cutting dust passing through the front end 11a of the window 11 may be smoothly drawn into the fixing cover 24.
As shown in
As shown in
According to the tip saw cutter 1 of the present embodiment configured as described above, the distances X1, X2 between the inner wall surface 24a of the fixing cover 24 and the tooth tip 22a may be set longer than the distance T between the tooth tip 22a and the tooth bottom 22b and shorter than twice as long as this distance T (the distance T<the distance X1, X2<the distance T×2). The distances X1, X2 are set within the above ranges in the range of a length from the lower end of the fixing cover 24 to the height H of the rotational center of the circular saw blade 22 (a height of an axis of the output shaft 39 as measured from the upper surface of the base 10). Because the distances X1, X2 are respectively set longer than the distance T, cutting dust stored in the tooth bottom 22b may be smoothly emitted to the space in the area around the distances X1, X2 between the tooth tip 22a and the inner wall surface 24a of the fixing cover 24, thereby improving the dust collection efficiency by the cutting dust collection box 25.
Furthermore, because the distances X1, X2 are set shorter than twice as long as the distance T, the rotational flow of the circular saw blade 22 can fully and influentially act on cutting dust in the space between the tooth tip 22a and the inner wall surface 24a of the fixing cover 24. This allows the cutting dust emitted into the space to be efficiently transferred to the cutting dust collection box 25. In this way, the distances X1, X2 are set such that cutting dust can be emitted from the tooth bottom 22b and the rotational flow can act on cutting dust in a sufficient manner.
Also, because the distance Y between the front end 11a of the window 11 in the base 10 and the tooth tip 22a of the circular saw blade 22 is set longer than the distance T from the tooth bottom 22b to the tooth tip 22a, and shorter than twice as long as the distance T, cutting dust stored in the tooth bottom 22b can be smoothly emitted to the space in the vicinity of the distance Y and collected into the fixing cover 24. Furthermore, because the distance Y is set shorter than twice as long as the distance T, the rotational flow of the circular saw blade 22 can fully act on the emitted cutting dust, thus allowing the cutting dust to be flown into the fixing cover 24 in a reliable manner. In this respect, dust collection efficiency can be more improved.
Furthermore, in the exemplified embodiment, the distance X1 between the tooth tip 22a and the inner wall surface 24a of the fixing cover 24 at the lower end of the fixing cover 24 and the distance X2 at the height H of the rotational center of the circular saw blade 22 (height of the axis of the output shaft 39), relating to a position in the up-to-down direction, may be set longer than the distance T and shorter than twice as long as the distance T. Especially, the distance X2 is set at the height H of the rotational center where a distance between the tooth tip 22a and the inner wall surface 24a of the fixing cover 24 is minimized, thereby improving dust collection efficiency.
Furthermore, the distance X1 is set longer than the distance Y between the front end 11a of the window 11 in the base 10 and the tooth tip 22a of the circular saw blade 22 on an upstream side before the dust collection opening 24b of the cutting dust collection box 25. Because of this configuration, cutting dust can be smoothly emitted from the tooth bottom 22b into the dust collection opening 24b leading to the cutting dust collection box 25, thereby improving dust collection efficiency.
Furthermore, in the exemplified embodiment, the guide member 40 is provided to guide cutting dust on the side of the dust collection opening 24b. Because of the presence of the guide member 40, cutting dust can be efficiently emitted to the dust collection opening 24b.
Furthermore, the guide member 40 is arranged in a tilting manner such that an outside of the guide member 40 in a radial direction of the circular saw blade 22 is displaced toward a front side in a rotational direction of the circular saw blade 22. Also, the guide member 40 has a fork shape extending on both sides, in a thickness direction, of the circular saw blade 22. Because of this configuration, dust collection efficiency through the dust collection opening 24b can be furthermore improved.
Various modifications can be made to the above described embodiment. For example, the distances X1, X2 between the tooth tip 22a and the inner wall surface 24a of the fixing cover 24, or the distance Y between the tooth tip 22a and the front end 11a of the window 11 can be modified within a range longer than the distance T between the tooth tip 22a and the tooth bottom 22b and also shorter than twice as long as the distance T.
In the exemplified embodiment, the distance X1 is set at the lower end of the fixing member 24 and the distance X2 is set at the height H of the rotational center of the circular saw blade 22. However, the distance between the tooth tip 22a and the inner wall surface 24a of the fixing cover 24 may be properly set with respect to the distance T of the circular saw blade, based on a height position of the dust collection opening 24b.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-093897 | May 2018 | JP | national |
The present application is a U.S. National Phase entry of, and claims propriety to, PCT Application No. PCT/JP2019/018376, filed May 8, 2019, which claims priority to Japanese Patent Application No. 2018-093897, filed May 15, 2018, both of which are incorporated herein by reference in their entireties for all purposes.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/018376 | 5/8/2019 | WO | 00 |
