Circular saw

Abstract

The invention provides a circular saw. A circular saw is provided with: a circular saw blade that is substantially circular and rotatable; a motor for providing rotational driving force to the circular saw blade; and a battery mounting part configured to detachably mount a battery for supplying power to the motor. The circular saw blade has a diameter of 300 mm or more and 460 mm or less. Therefore, the cutting efficiency of the circular saw using the battery as the power supply is improved.

Description

Technical Field

[0001] The present invention relates to a circular saw. Background Art

[0002] A cutting machine called a portable circular saw (hereinafter simply referred to as a circular saw) has a base and a main body. The main body has an electric motor and a circular saw blade that is driven to rotate by the electric motor. The main body is disposed on one side with respect to the base, but a part of the circular saw blade protrudes beyond the base to the other side. When using the circular saw, the user brings the lower surface of the base into contact with the workpiece to be cut while the circular saw blade is rotating, and moves the cutting machine forward. Thereby, the circular saw blade protruding beyond the base cuts the workpiece to be cut. Japanese Patent Application Laid-Open No. 2020-116834 discloses a portable circular saw, which uses a battery as a power source for the electric motor as one such circular saw. Summary of the Invention [Technical Problem to be Solved by the Invention]

[0003] In the prior art, as shown in Japanese Patent Application Laid-Open No. 2020-116834, in a circular saw using a battery as a power source, the diameter of the circular saw blade is small (for example, 125 mm in diameter), and the cutting efficiency is poor. This problem is not limited to portable circular saws, but also exists in circular saws fixedly installed on a workbench for use. Accordingly, it is desired to improve the cutting efficiency of circular saws using a battery as a power source.

[0004] This specification discloses a circular saw. The circular saw may have: a circular saw blade that can rotate; an electric motor that provides a rotational driving force to the circular saw blade; and a battery mounting portion configured to detachably mount a battery for supplying power to the electric motor. The diameter of the circular saw blade may be 300 mm or more and 460 mm or less.

[0005] According to this circular saw, since the diameter of the circular saw blade is 300 mm or more and 460 mm or less, the radius of curvature of the circular saw blade is large (the curvature is small) compared to a battery-powered circular saw with a small-diameter circular saw blade in the prior art. Therefore, even for a workpiece to be cut having a large cross-section, it can be cut efficiently.

[0006] This specification discloses a circular saw. The circular saw may have: a circular saw blade that can rotate; an electric motor that provides a rotational driving force to the circular saw blade; a final output shaft that can rotate and is used to transmit the rotational driving force of the electric motor and has the circular saw blade mounted thereon; and a battery mounting portion configured to detachably mount a battery for supplying power to the electric motor. When the torque of the final output shaft is 5 N / m, the value obtained by multiplying the circumferential speed of the tip of the circular saw blade by the diameter of the circular saw blade may be 6.0 m 2 / s or more.

[0007] According to this circular saw, even for a workpiece to be cut with a large cross-section, by rotating a circular saw blade with a sufficient diameter at a sufficient circumferential speed, the workpiece can be efficiently cut thereby. Description of the Drawings

[0008] Figure 1 is a perspective view of a circular saw according to an embodiment of the present invention. Figure 2 is a perspective view of the circular saw. Figure 3 is a perspective view of the circular saw with the battery removed. Figure 4 is a front view of the circular saw with some structural components removed. Figure 5 is a left view showing the first example of the dimensions of the circular saw. Figure 6 is a top view showing the first example of the dimensions of the circular saw. Figure 7 is a left view showing the second example of the dimensions of the circular saw. Figure 8 is a top view showing the second example of the dimensions of the circular saw. Figure 9 is a left view showing the third example of the dimensions of the circular saw. Figure 10 is a top view showing the third example of the dimensions of the circular saw. Figure 11 is a left view of the circular saw according to the second embodiment. Figure 12 is a right view of the circular saw according to the second embodiment. Figure 13 is a top view of the circular saw according to the second embodiment. Figure 14 is a bottom view of the circular saw according to the second embodiment. Figure 15 is a front view of the circular saw according to the second embodiment. Figure 16 is a rear view of the circular saw according to the second embodiment. Figure 17 is a graph showing the relationship between the torque of the final output shaft and the product of the circumferential speed of the cutting edge and the diameter of the circular saw blade. Figure 18 is a top view of the circular saw according to the third embodiment. [Description of Reference Numerals] 10: Portable circular saw; 11: Motor housing; 12: Gearbox; 13: Battery mounting part; 14: Battery; 15: Center of gravity of the circular saw; 16: Center of gravity of the battery; 20: Base; 21: Through hole; 22: Gusset plate; 23: Fixed rod; 24: Bracket; 25: Support shaft; 26: Depth guide; 27: Fixed rod; 30: Main body part; 33: Fixed cover; 33a: Protrusion; 34: Movable cover; 35: Circular saw blade; 36: Fastening member; 41: Electric motor; 42: Motor shaft; 43: Reduction mechanism; 44: Driving gear; 45: Driven gear; 46: Spindle; 50: First handle; 51: First gripping part; 52: Front edge part; 53: First center point; 54: First half region; 55: Switch lever; 60: Second handle; 61: Second gripping part; 62: Front edge part; 63: Second center point; 64: Second half region; AX: Rotation axis of the circular saw blade. Detailed implementation mode

[0009] Hereinafter, representative and non-limiting specific examples of the present invention will be described in detail with reference to the drawings. This detailed description merely shows the details of the preferred examples for implementing the present invention to those skilled in the art, and does not mean to limit the scope of the present invention. In addition, the additional features and technical solutions disclosed below can be used alone or together with other features or technical solutions in order to further provide an improved device, its manufacturing method and usage method.

[0010] In addition, the combination of the features or processes disclosed in the following detailed description is not necessary in the broadest sense when implementing the present invention, and is merely described for specifically illustrating the representative specific examples of the present invention. Moreover, the various features of the above and the following representative specific examples and the various features described in the independent and dependent claims do not have to be combined as in the specific examples here or in the order listed when providing additional and useful embodiments of the present invention.

[0011] All the features described in this specification and / or the claims are different from the structures of the features described in the embodiments and / or the claims, and are disclosed separately and independently of each other, as a limitation of the specific matters of the original application disclosure and the claims. Moreover, the descriptions related to all numerical ranges and groups or sets represent the disclosure of these intermediate structures, as a limitation of the specific matters of the original application disclosure and the claims.

[0012] In one or more embodiments, the circular saw may be configured such that the circular saw blade rotates at a circumferential speed of 70.0 m / s or less under no load. With this configuration, the difference in the circumferential speed of the circular saw blade between no load and load can be reduced. Therefore, the behavior of the circular saw when starting to cut the workpiece to be cut is stable. As a result, the usability of the user can be improved, and the cut surface of the workpiece to be cut can be made flatter.

[0013] In one or more embodiments, the circular saw may be configured such that the circular saw blade rotates at a circumferential speed of 50.0 m / s or less under no load. With this configuration, the difference in the circumferential speed of the circular saw blade between no load and load can be reduced. Therefore, the behavior of the circular saw when starting to cut the workpiece to be cut is further stabilized.

[0014] In one or more embodiments, the circular saw may be configured such that the circular saw blade rotates at a circumferential speed of 25.0 m / s or more under load. With this configuration, even for a workpiece to be cut having a large cross-section, it is possible to perform cutting efficiently at a sufficient circumferential speed.

[0015] In one or more embodiments, the circular saw may be configured such that the circular saw blade rotates at a circumferential speed of 28.0 m / s or more under load. With this configuration, the workpiece to be cut can be cut more efficiently.

[0016] In one or more embodiments, the circular saw may be configured to rotate such that the force of the cutting edge of the circular saw blade under load is 20.0 N or more. The "force of the cutting edge" refers to the force that causes the cutting edge to act on the cutting portion of the workpiece to be cut. With this configuration, even for a workpiece to be cut having a large cross-section, it is possible to apply a sufficient force to the workpiece to be cut and cut the workpiece to be cut efficiently.

[0017] In one or more embodiments, the circular saw may be configured to rotate such that the force of the cutting edge of the circular saw blade under load is 30.0 N or more. With this configuration, the workpiece to be cut can be cut more efficiently.

[0018] In one or more embodiments, the circular saw may have a battery. The rated voltage of the battery may be 18 V or more and 80 V or less. With this configuration, even for a workpiece to be cut having a large cross-section, it is possible to cut the workpiece to be cut efficiently with a sufficient battery output.

[0019] In one or more embodiments, the circular saw may have a battery. The rated voltage of the battery may be 36 V. With this configuration, it is possible to achieve a good balance between the compactness (lightweight) and high output of the circular saw.

[0020] In one or more embodiments, it is possible that the circular saw has a speed reduction mechanism configured to reduce the rotational driving force of the motor and transmit it to the circular saw blade. It is possible that the reduction ratio of the speed reduction mechanism is 7 or more. According to this structure, even for a workpiece with a large cross-section, the workpiece can be efficiently cut with sufficient torque.

[0021] In one or more embodiments, it is possible that the circular saw is in the form of a portable circular saw. It is possible that the portable circular saw has a first handle and a second handle. The first handle has a first gripping portion. When the direction in which the portable circular saw cuts is defined as the front side and the side opposite to the front side is defined as the rear side, the second handle is disposed on the front side of the first handle and has a second gripping portion. It is possible that the battery mounting portion is configured such that when the battery is mounted on the battery mounting portion, the whole battery is located between the front edge of the first gripping portion and the front edge of the second gripping portion in the front-rear direction. According to this structure, since the heavy battery is located between the front edge of the first gripping portion and the front edge of the second gripping portion, even though the portable circular saw has a circular saw blade with a relatively large diameter (a circular saw blade with a diameter of 300 mm or more), the weight balance when the user holds the portable circular saw by gripping the first gripping portion and the second gripping portion can be improved. Therefore, the user can stably hold the portable circular saw with less force.

[0022] In one or more embodiments, it is possible that the circular saw is in the form of a portable circular saw. It is possible that the portable circular saw has a first handle and a second handle. The first handle has a first gripping portion. When the direction in which the portable circular saw cuts is defined as the front side and the side opposite to the front side is defined as the rear side, the second handle is disposed on the front side of the first handle and has a second gripping portion. It is possible that the center of gravity of the circular saw in the state where the battery is mounted on the battery mounting portion is below the lower edges of the first gripping portion and the second gripping portion in the up-down direction of the posture when using the portable circular saw. According to this structure, when the user holds the portable circular saw by gripping the first gripping portion and the second gripping portion, the portable circular saw can be stably held with less force.

[0023] In one or more embodiments, the circular saw may be a portable circular saw. The portable circular saw may have a first handle, a second handle, and a battery. The first handle has a first gripping portion. When the direction in which the portable circular saw cuts is defined as the front side and the side opposite to the front side is defined as the rear side, the second handle is disposed on the front side of the first handle and has a second gripping portion. The center of gravity of the battery in a state where the battery is mounted on the battery mounting portion is located below the lower edge portion of the first gripping portion and below the lower edge portion of the first gripping portion in the vertical direction of the posture when using the portable circular saw. Since the center of gravity of the battery, which is a heavy object, is located below the gripping portions of the first gripping portion and the second gripping portion, when the user holds the first gripping portion and the second gripping portion to hold the portable circular saw, the portable circular saw can be stably held with less force.

[0024] In one or more embodiments, the circular saw may be a portable circular saw. The portable circular saw may have a first handle and a second handle. The first handle has a first gripping portion. When the direction in which the portable circular saw cuts is defined as the front side and the side opposite to the front side is defined as the rear side, the second handle is disposed on the front side of the first handle and has a second gripping portion. When the distance between the center point of the area where the user actually grips the first gripping portion of the first gripping portion in the front-rear direction, that is, the first center point, and the center point of the second gripping portion, that is, the second center point, is set as L1, and the distance between the first center point in the front-rear direction and the center of gravity of the circular saw in a state where the battery is mounted on the battery mounting portion, that is, the first center of gravity, is set as L2, the value of L2 / L1 is 0.5 or more and 0.7 or less. According to this structure, even though the portable circular saw has a circular saw blade with a relatively large diameter (a circular saw blade with a diameter of 300 mm or more), the weight balance when the user holds the first gripping portion and the second gripping portion to hold the portable circular saw can be improved. Therefore, the user can stably hold the portable circular saw with less force.

[0025] In one or more embodiments, when the distance between the center point of the area where the user actually grips the first gripping portion of the first gripping portion in the vertical direction of the posture when using the portable circular saw, that is, the first center point, and the center point of the second gripping portion, that is, the second center point, is set as L3, and the distance between the first center point in the vertical direction and the center of gravity of the circular saw in a state where the battery is mounted on the battery mounting portion, that is, the first center of gravity, is set as L4, the value of L4 / L3 is 3.4 or more and 3.8 or less. According to this structure, the weight balance when the user holds the first gripping portion and the second gripping portion to hold the portable circular saw can be improved.

[0026] In one or more embodiments, it may be that when the distance between the first center point, which is the center point of the region where the user actually holds the first holding part of the first holding part in the set front-rear direction, and the second center point, which is the center point of the second holding part, is L1, and the distance between the first center point in the set front-rear direction and the second center of gravity, which is the center of gravity of the battery in the state where the battery is mounted on the battery mounting part, is L5, the value of L5 / L1 is 0.1 or more and 0.3 or less. According to this structure, it is possible to improve the weight balance when the user holds the first holding part and the second holding part to hold the portable circular saw.

[0027] In one or more embodiments, it may be that when the distance between the first center point, which is the center point of the region where the user actually holds the first holding part of the first holding part in the set up-down direction when the posture of the portable circular saw during use is set, and the second center point, which is the center point of the second holding part, is L3, and the distance between the first center point in the set up-down direction and the second center of gravity, which is the center of gravity of the battery in the state where the battery is mounted on the battery mounting part, is L6, the value of L6 / L3 is 2.8 or more and 3.2 or less. According to this structure, it is possible to improve the weight balance when the user holds the first holding part and the second holding part to hold the portable circular saw.

[0028] In one or more embodiments, it may be that when the distance between the first center point, which is the center point of the region where the user actually holds the first holding part of the first holding part in the direction in which the rotation axis of the circular saw blade extends, i.e., the axis direction, and the second center point, which is the center point of the second holding part, is L7, and the distance between the first center point in the axis direction and the first center of gravity, which is the center of gravity of the circular saw in the state where the battery is mounted on the battery mounting part, is L8, the value of L8 / L7 is 0.4 or more and 0.7 or less. According to this structure, it is possible to improve the weight balance when the user holds the first holding part and the second holding part to hold the portable circular saw.

[0029] In one or more embodiments, it may be that when the distance between the first center point, which is the center point of the region where the user actually holds the first holding part of the first holding part in the direction in which the rotation axis of the circular saw blade extends, i.e., the axis direction, and the second center point, which is the center point of the second holding part, is L7, and the distance between the first center point in the axis direction and the second center of gravity, which is the center of gravity of the battery in the state where the battery is mounted on the battery mounting part, is L9, the value of L9 / L7 is 1.3 or more and 1.5 or less. According to this structure, it is possible to improve the weight balance when the user holds the first holding part and the second holding part to hold the portable circular saw.

[0030] In one or more embodiments, it is possible that the circular saw is a portable circular saw having a base with a through-hole through which the circular saw blade can pass. It is possible that when the side where the motor is located with respect to the base is defined as the upper side and the opposite side is defined as the lower side, in a state where the circular saw blade is orthogonal to the base and the protruding distance of the circular saw blade passing through the through-hole protruding downward with respect to the base is maximum, the protruding distance of the circular saw blade on the lower side is 100 mm or more. According to this structure, compared with the existing circular saw, a workpiece with a greater thickness can be cut.

[0031] In one or more embodiments, it is possible that in a state where the circular saw blade is orthogonal to the base and the protruding distance of the circular saw blade passing through the through-hole protruding downward with respect to the base is maximum, the protruding distance of the circular saw blade on the lower side is 150 mm or more. According to this structure, a workpiece with an even greater thickness can be cut.

[0032] It is possible that when the torque of the final output shaft is 5 N / m, the value obtained by multiplying the circumferential speed of the tip of the circular saw blade by the diameter of the circular saw blade is 10.0 m 2 / s or more. According to this structure, by rotating the circular saw blade with a sufficient diameter at a sufficient circumferential speed, the workpiece can be cut more efficiently.

[0033] In one or more embodiments, it is possible that the circular saw is a portable circular saw having a base with a through-hole through which the circular saw blade can pass. It is possible that when the side where the circular saw advances when cutting a workpiece is defined as the front side, the opposite direction is defined as the rear side, the side where the motor is located with respect to the base is defined as the upper side, the opposite side is defined as the lower side, the direction orthogonal to the front-rear direction and the up-down direction is defined as the left-right direction, the right side when observing the front side from the rear side is defined as the right side, and the opposite side is defined as the left side, the circular saw blade is located on the left side with respect to the motor. According to this structure, when the user stands on the left side with respect to the circular saw and uses the circular saw, the motor is not on the user's line of sight with respect to the circular saw blade. As a result, when operating the circular saw, the visibility of the circular saw blade visible between the front part of the fixed cover and the front part of the base can be improved, especially the visibility of the part where the circular saw blade intersects the ink line on the workpiece.

[0034] In one or more embodiments, it is possible that a circular saw has a first handle, a second handle, and a third handle. The first handle has a first gripping portion that is at least partially located on the rear side of the circular saw blade in the front-rear direction. The second handle has a second gripping portion that is located on the front side of the motor in the front-rear direction and on the right side of the circular saw blade in the left-right direction. The third handle has a third gripping portion that is located on the left side of the circular saw blade in the left-right direction. According to this structure, the user can separately use the gripped handles according to the user's working posture. For example, the user can use the circular saw by gripping the first gripping portion and the second gripping portion with both hands respectively. Or, the user can use the circular saw by gripping the first gripping portion and the third gripping portion with both hands respectively. Moreover, since the distance between the first gripping portion and the second gripping portion in the front-rear direction becomes larger, when the user uses the circular saw by gripping the first gripping portion and the second gripping portion with both hands respectively, the circular saw can be held more stably.

[0035] In one or more embodiments, it is possible that the third gripping portion is located on the front side of the motor in the front-rear direction. According to this structure, since the distance between the first gripping portion and the third gripping portion in the front-rear direction becomes larger, when the user uses the circular saw by gripping the first gripping portion and the third gripping portion with both hands respectively, the circular saw can be held more stably.

[0036] Hereinafter, with reference to Figures 1 - 6 , a portable circular saw (hereinafter simply referred to as a circular saw) 10 of an exemplary embodiment will be described in more detail. In the following description, when the user holds the circular saw 10 and cuts a workpiece to be cut (in other words, when the circular saw 10 is in the posture during use), the side where the circular saw 10 advances (the side where the circular saw blade 35 described later cuts) is defined as the front side of the circular saw 10, and the opposite direction is defined as the rear side of the circular saw 10. In addition, at this time, the side located above the vertical direction is defined as the upper side of the circular saw 10, and the opposite side is defined as the lower side of the circular saw 10. Moreover, the direction orthogonal to the front-rear direction and the up-down direction is defined as the left-right direction. Among the left-right directions, the right side when observing the front side from the rear side is defined as the right side of the circular saw 10, and the opposite side is defined as the left side of the circular saw 10.

[0037] As Figure 1 shown, the circular saw 10 has a base 20 and a main body portion 30. The base 20 has a substantially rectangular outer shape. The length direction of the base 20 is the front-rear direction. The base 20 has a flat lower surface for abutting against the workpiece to be cut during cutting.

[0038] As Figure 1 shown, the main body portion 30 is disposed substantially above the base 20. As Figures 1 - 4As shown, the main body portion 30 includes a motor housing 11, a gearbox 12, a first handle 50, a second handle 60, a motor 41, a circular saw blade 35, a fixed cover 33, and a movable cover 34.

[0039] A part of the circular saw blade 35 penetrates through the through hole 21 of the base 20 and protrudes downward from the base 20. The circular saw blade 35 is also referred to as a tipped saw blade (English name: tipped saw blade) and has a substantially circular shape. The circular saw blade 35 is configured to rotate about a rotation axis AX extending in the left - right direction by the rotational driving force provided by the motor 41 (refer to Figure 4 ). The fixed cover 33 covers an upper side portion of the circular saw blade 35 in an arc shape. The movable cover 34 covers the circular saw blade 35 below the fixed cover 33. The movable cover 34 is configured to be able to retract along the outer peripheral edge portion of the circular saw blade 35, and in normal times, is biased by a biasing member (not shown) to Figure 1 the position shown. When the circular saw 10 is in use, it is pushed by the workpiece to be cut and retracts backward, thereby exposing the portion of the circular saw blade 35 located below the base 20.

[0040] As Figure 2 and Figure 3 shown, the motor housing 11 is disposed on the left side of the fixed cover 33. Inside the motor housing 11, a motor 41 for providing a rotational driving force to the circular saw blade 35 is housed. A battery mounting portion 13 (refer to Figure 3 ) is formed at the trailing edge portion of the motor housing 11, and the battery mounting portion 13 is configured to detachably mount a battery 14 for supplying power to the motor 41 (refer to Figure 2 ). The battery mounting portion 13 has electrical terminals for electrically connecting to the battery 14 and a guide groove that engages with a convex portion of the battery. In the present embodiment, the battery mounting portion 13 is configured such that the battery 14 can be mounted by sliding the battery 14 downward along the guide groove from above. As Figure 2 shown, by mounting the battery 14 with the longitudinal direction of the battery 14 aligned with the up - down direction, the center of gravity of the battery 14 during installation of the battery 14 can be located more forward compared to other layouts.

[0041] As Figure 3 shown, the gearbox 12 is disposed between the fixed cover 33 and the motor housing 11 in the left - right direction. Inside the gearbox 12, a mechanical mechanism (for example, a reduction mechanism 43, a main shaft 46, etc. described below) for transmitting the rotational driving force of the motor 41 to the circular saw blade 35 is housed. As Figure 4As shown, the motor shaft 42 of the electric motor 41 extends in the left - right direction. Additionally, below the motor shaft 42, the main shaft 46 extends parallel to the motor shaft 42. The main shaft 46 penetrates through the right surface of the gearbox 12 and the left surface of the fixed cover 33 from within the gearbox 12 and extends to the right, and a circular saw blade 35 is mounted at its tip by a fixing member 36. The circular saw blade 35 extends in a manner orthogonal to the lower surface of the base 20.

[0042] As Figure 4 shown, the motor shaft 42 is operably connected to the main shaft 46 via a speed - reducing mechanism 43. The speed - reducing mechanism 43 has a driving gear 44 mounted around the motor shaft 42 and a driven gear 45 mounted around the main shaft 46. The speed - reducing mechanism 43 reduces the rotational driving force of the electric motor 41 at a reduction ratio determined according to the gear ratio of the driving gear 44 and the driven gear 45, transmits it to the main shaft 46, and further transmits it to the circular saw blade 35.

[0043] As Figure 2 and Figure 3 shown, the first handle 50 is in the form of an annular handle. The first handle 50 extends in a cylindrical shape along the arc shape of the fixed cover 33 at the upper edge portion on the rear side of the fixed cover 33 in such a way that a gap (a gripping space) is formed between the fixed cover 33 and the first handle 50. As a result, a first gripping portion 51 into which fingers can be placed to grip is formed on the first handle 50. The first gripping portion 51 is a portion that extends in a cylindrical shape with a substantially identical diameter and is used for the user to hold by hand when using the circular saw 10. A switch lever 55 for operating the start and stop of the electric motor 41 is provided at the front edge portion on the upper side of the first gripping portion 51. Therefore, the user holds the position shifted upward in the first gripping portion 51 in such a way that the fingers can reach the switch lever 55.

[0044] As Figure 2 and Figure 3 shown, the second handle 60 is disposed on the front side of the first handle 50. In the present embodiment, the second handle 60 is in the form of an annular handle. However, it may be in the form of a straight rod handle that extends linearly to the left from the left surface of the fixed cover 33. The second handle 60 extends in a cylindrical shape in such a way that it bridges the portion on the front side of the electric motor 41 in the left surface of the fixed cover 33 and the upper edge portion on the front side of the motor housing 11. The portion of the second handle 60 that extends in the left - right direction with a substantially identical diameter functions as a second gripping portion 61 for the user to hold by hand when using the circular saw 10.

[0045] When using the circular saw 10, the user holds the first gripping portion 51 of the first handle 50 and the second gripping portion 61 of the second handle 60 with their hands and lifts it. When the switch lever 55 is pressed, the circular saw blade 35 rotates by the driving force of the motor 41. In this state, the user brings the lower surface of the base 20 (the portion in front of the circular saw blade 35) into contact with the workpiece to be cut, and moves the circular saw 10 forward. As a result, the circular saw blade 35 that protrudes downward beyond the lower surface of the base 20 cuts the workpiece to be cut along the moving direction of the circular saw 10.

[0046] As Figure 1 and Figure 2 shown, an angle plate 22 and a fixing rod 23 are installed at the leading edge portion. A bracket 24 having a bifurcated shape is installed behind the angle plate 22. As Figure 1 shown, the support shaft 25 is supported by the bracket 24 in a state of passing through the leading edge portion of the bracket 24 and the fixing cover 33 disposed between the bifurcated shapes of the bracket 24. With such a structure, the main body portion 30 is supported by the support shaft 25 on its front side, and in addition, can swing relative to the base 20 with the support shaft 25 as the center.

[0047] The main body portion 30 is supported by the depth guide 26 on its rear side. The swing position of the main body portion 30 (circular saw blade 35) relative to the base 20 (i.e., the cutting depth) can be adjusted by the depth guide 26 and the fixing rod 27. Since such a structure is a well-known structure, the description thereof is omitted here.

[0048] Moreover, the main body portion 30 (circular saw blade 35) is configured to be able to tilt relative to the base 20 about a tilting axis extending in the front-rear direction. According to this structure, the workpiece to be cut can be cut obliquely. Such a tilting action is achieved by the angle plate 22 and the fixing rod 23. Since the structure for tilting using the angle plate 22 is a well-known structure, the description thereof is omitted.

[0049] In the above circular saw 10, a circular saw blade having a diameter of 300 mm or more and 460 mm or less is used as the circular saw blade 35. According to this structure, compared with the existing battery-powered circular saw having a circular saw blade with a smaller diameter (for example, a diameter of 125 mm), the radius of curvature of the circular saw blade 35 is large. Therefore, even for a workpiece to be cut having a large cross-section, it can be cut efficiently. The diameter of the circular saw blade 35 can be 360 mm or more and 460 mm or less. In this way, the cutting efficiency can be further improved. In the present embodiment, a circular saw blade of 415 mm is disclosed as an example.

[0050] Furthermore, the circular saw 10 can be configured such that the circular saw blade 35 rotates at a circumferential speed of 25.0 m / s or more under load. With this configuration, even for a workpiece to be cut having a large cross-section, it is possible to efficiently perform cutting at a sufficient circumferential speed. The circumferential speed under load can be 28.0 m / s or more. In this way, the cutting efficiency can be further improved. In the present embodiment, a circumferential speed of 29.7 m / s under load is disclosed as an example.

[0051] Furthermore, the circular saw 10 can be configured such that the circular saw blade 35 rotates at a circumferential speed of 70.0 m / s or less under no load. With this configuration, it is possible to reduce the difference in the circumferential speed of the circular saw blade 35 between under no load and under load. Therefore, the behavior of the circular saw 10 when starting to cut the workpiece to be cut is stable. As a result, the usability for the user can be improved, and the cutting surface of the workpiece to be cut can be made flatter. The circumferential speed under no load can be 50.0 m / s or less. In this way, the difference in the circumferential speed of the circular saw blade 35 between under no load and under load can be further reduced. In the present embodiment, a circumferential speed of 45.6 m / s under no load is disclosed as an example.

[0052] Furthermore, the circular saw 10 can be configured to rotate such that the force at the tip of the circular saw blade 35 under load is 20.0 N or more. With this configuration, even for a workpiece to be cut having a large cross-section, it is possible to apply a sufficient force to the workpiece to be cut and efficiently cut the workpiece to be cut. The force at the tip of the circular saw blade 35 under load can be 30.0 N or more. With this configuration, the workpiece to be cut can be cut more efficiently. In the present embodiment, a force at the tip of 40.5 N under load is disclosed as an example.

[0053] Furthermore, a battery with a rated voltage of 18 V or more and 80 V or less can be used as the battery 14. With this configuration, even for a workpiece to be cut having a large cross-section, it is possible to efficiently cut the workpiece to be cut with sufficient battery output. The rated voltage of the battery 14 can be 36 V. In this way, it is possible to achieve a good balance between the compactification (weight reduction) and high output of the circular saw 10.

[0054] Furthermore, the reduction ratio of the reduction mechanism 43 can be set to 7 or more. With this configuration, even for a workpiece to be cut having a large cross-section, it is possible to efficiently cut the workpiece to be cut with sufficient torque.

[0055] Hereinafter, various features of an example related to the layout of the circular saw 10 will be described. In the following description, the cutting depth of the circular saw blade 35 is set to the maximum value by the depth guide 26, and the circular saw blade 35 is set to be parallel to the vertical direction when viewed in the front-rear direction. However, the circular saw 10 can be configured in such a way that the various features described below are also applicable when the cutting depth of the circular saw blade 35 is set to any value between the minimum value and the maximum value, and when the circular saw blade 35 forms an angle with respect to the vertical direction at any angle when viewed in the front-rear direction. Alternatively, the circular saw 10 can be configured in such a way that at least a part of the various features described below is applicable only when the cutting depth of the circular saw blade 35 is set to a specific value between the minimum value and the maximum value and / or when the circular saw blade 35 forms an angle with respect to the vertical direction at a specific angle when viewed in the front-rear direction.

[0056] In the present embodiment, as Figure 5 and Figure 6 shown, in a state where the battery 14 is mounted on the battery mounting portion 13, in the front-rear direction, the battery 14 is located between the front edge portion 52 of the first gripping portion 51 of the first handle 50 and the front edge portion 62 of the second gripping portion 61 of the second handle 60. Here, the front edge portion 52 refers to the portion located on the rearmost side in the first half region 54 ( Figure 3 shown shaded). The first half region 54 is a region in the first gripping portion 51 of a cylindrical body having substantially the same diameter, which is a half region in the circumferential direction toward the rotation axis AX of the circular saw blade 35 (one half of the outer peripheral surface of the cylindrical body on the side closer to the rotation axis AX). In Figure 3 , only the left half of the first half region 54 can be observed. In addition, the front edge portion 62 refers to the portion located on the foremost side in the second half region 64 ( Figure 3 shown shaded). The second half region 64 is a region in the second gripping portion 61 of a cylindrical body having substantially the same diameter, which is a half portion in the circumferential direction toward the rotation axis AX of the circular saw blade 35 (one half of the outer peripheral surface of the cylindrical body on the side closer to the rotation axis AX). In Figure 3 , only the rear half of the second half region 64 can be observed.

[0057] As in this embodiment, if the diameter of the circular saw blade 35 is increased, the weight of the circular saw blade 35 increases, and it is also necessary to increase the output of the battery 14 as a heavy object. Therefore, when adopting the same configuration as that of the existing circular saw using a circular saw blade with a small diameter, the weight balance when the user holds the circular saw 10 by gripping the first grip portion 51 and the second grip portion 61 deteriorates. However, according to the above configuration, since the battery 14 as a heavy object is located between the front edge portion 52 of the first grip portion 51 and the front edge portion 62 of the second grip portion 61 (that is, between the rearmost portion and the foremost portion of the portions for gripping by hand in the first grip portion 51 and the second grip portion 61), even if the circular saw blade 35 becomes larger in diameter, it is possible to improve the weight balance when the user holds the circular saw 10 by gripping the first grip portion 51 and the second grip portion 61. Therefore, the user can stably hold the circular saw 10 with less force.

[0058] Moreover, in the present embodiment, as Figure 5 shown, in a state where the battery 14 is mounted on the battery mounting portion 13, the center of gravity 15 of the circular saw (the center of gravity in a state where the battery 14 is mounted) is located below the lower edge portion of the first grip portion 51 and the lower edge portion of the second grip portion 61 in the vertical direction. According to such a configuration, it is also possible to improve the weight balance when the user holds the circular saw 10 by gripping the first grip portion 51 and the second grip portion 61.

[0059] Moreover, in the present embodiment, as Figure 5 shown, in a state where the battery 14 is mounted on the battery mounting portion 13, the center of gravity 16 of the battery 14 as a heavy object is located below the lower edge portion of the first grip portion 51 and the lower edge portion of the second grip portion 61 in the vertical direction. According to such a configuration, it is also possible to improve the weight balance when the user holds the circular saw 10 by gripping the first grip portion 51 and the second grip portion 61.

[0060] Moreover, in the present embodiment, the first grip portion 51, the second grip portion 61, the center of gravity 15 of the circular saw, and the center of gravity 16 of the battery 14 are arranged in a manner that satisfies the conditions described below. Specifically, first, as Figure 5 and Figure 6 shown, the center point of the region where the user actually grips the first grip portion 51 of the first grip portion 51 is defined as the first center point 53. In addition, the center point of the second grip portion 61 is defined as the second center point 63. When the user actually grips the first grip portion 51, the position where the fingers of the hand gripping the first grip portion 51 reach the switch lever 55 (that is, the position near the front edge portion in the first grip portion 51) is gripped. The first center point 53 is the center point determined by only focusing on the region where the user actually grips the first grip portion 51 at this time.

[0061] Moreover, as Figure 5As shown, the distance between the first center point 53 and the second center point 63 in the front-rear direction is defined as distance L1, and the distance between the first center point 53 and the center of gravity 15 of the circular saw in the front-rear direction is defined as distance L2. Moreover, as Figure 5 shown, the distance between the first center point 53 and the second center point 63 in the up-down direction is defined as distance L3, and the distance between the first center point 53 and the center of gravity 15 of the circular saw in the up-down direction is defined as distance L4. Moreover, as Figure 5 shown, the distance between the first center point 53 and the center of gravity 16 of the battery 14 in the front-rear direction is defined as distance L5, and the distance between the first center point 53 and the center of gravity 16 of the battery 14 in the up-down direction is defined as distance L6.

[0062] Moreover, as Figure 6 shown, the distance between the first center point 53 and the second center point 63 in the left-right direction (in other words, the direction in which the rotation axis AX of the circular saw blade 35 extends) is defined as distance L7, the distance between the first center point 53 and the center of gravity 15 of the circular saw in the left-right direction is defined as distance L8, and the distance between the first center point 53 and the center of gravity 16 of the battery 14 in the left-right direction is defined as distance L9.

[0063] A first example of the design dimensions of distances L1 to L9 at this time is shown in Figure 5 and Figure 6 , a second example is shown in Figure 7 and Figure 8 , and a third example is shown in Figure 9 and Figure 10 . The unit of the dimensions shown in the figures is "mm". Specifically, in the first example, distance L1 is 323.5 mm, distance L2 is 192.7 mm, distance L3 is 51.3 mm, distance L4 is 184.0 mm, distance L5 is 49.0 mm, distance L6 is 148.6 mm, distance L7 is 87.0 mm, distance L8 is 48.1 mm, and distance L9 is 117.9 mm. In the second example, distance L1 is 323.5 mm, distance L2 is 199.9 mm, distance L3 is 51.3 mm, distance L4 is 185.8 mm, distance L5 is 59.0 mm, distance L6 is 151.4 mm, distance L7 is 87.0 mm, distance L8 is 45.1 mm, and distance L9 is 117.9 mm. In the third example, distance L1 is 323.5 mm, distance L2 is 204.2 mm, distance L3 is 51.3 mm, distance L4 is 187.3 mm, distance L5 is 67.5 mm, distance L6 is 160.1 mm, distance L7 is 87.0 mm, distance L8 is 43.2 mm, and distance L9 is 117.9 mm. In the first example, the capacity of the battery 14 is 8 Ah, in the second example, the capacity of the battery 14 is 5 Ah, and in the third example, the capacity of the battery 14 is 4 Ah.

[0064] In any one of the first to third examples, the distances L1 to L9 satisfy the following formulas (1) to (4). 0.5 ≦ L2 / L1 ≦ 0.7 ··· (1) 3.4 ≦ L4 / L3 ≦ 3.8 ··· (2) 0.1 ≦ L5 / L1 ≦ 0.3 ··· (3) 2.8 ≦ L6 / L3 ≦ 3.2 ··· (4) 0.4 ≦ L8 / L7 ≦ 0.7 ··· (5) 1.3 ≦ L9 / L7 ≦ 1.5 ··· (6) In the case of satisfying such conditions, it is also possible to improve the weight balance when the user holds the first grip portion 51 and the second grip portion 61 to hold the circular saw 10. In addition, the layout of the circular saw 10 can be determined in such a way as to satisfy at least one of the above (1) to (6).

[0065] Hereinafter, with reference to Figures 11 - 17 , only the points different from the first embodiment will be described for the second embodiment. As clearly shown in Figure 12 and Figure 13 , in the circular saw 110 according to the second embodiment, contrary to the circular saw 10 in which the circular saw blade 35 is located on the right side of the motor 41 (refer to Figure 3 ), the circular saw blade 35 is located on the left side of the motor 41 (motor housing 11). According to this layout, when the user stands on the left side of the circular saw 110 and uses the circular saw, the motor housing 11 is not on the user's line of sight with respect to the circular saw blade 35. In addition, in the left - right direction, the circular saw blade 35 is located closer to the user. Therefore, when operating the circular saw 110, the visibility of the circular saw blade 35 visible between the front portion of the fixed cover 33 and the front portion of the base 20 can be improved, and in particular, the visibility of the portion where the circular saw blade 35 intersects the ink line on the workpiece to be cut can be improved.

[0066] As Figures 11 - 16 shows, the circular saw 110 has a third handle 170 in addition to the first handle 50 and the second handle 60. The shape of the first handle 50 and the position of the first handle 50 with respect to the base 20 are the same as those in the first embodiment. That is, the first handle 50 is located at the rear side and the upper edge portion of the fixed cover 33, and at least a part of the first grip portion 51 of the first handle 50 is located at the rear side of the circular saw blade 35.

[0067] The second handle 60, similar to the first embodiment, has a second gripping portion 61. The second handle 60 extends in a cylindrical shape so as to span a portion in front of the motor 41 in the right surface of the fixed cover 33 and the upper edge portion in front of the motor housing 11. That is, contrary to the circular saw 10 according to the first embodiment, the second handle 60 is located on the right side with respect to the circular saw blade 35. In addition, the second gripping portion 61 of the second handle 60 is located in front of the motor 41 (motor housing 11). In this regard, it is the same as the first embodiment.

[0068] In the present embodiment, the third handle 170 is in the form of a straight rod handle. The third handle 170 is located on the left side of the circular saw blade 35. In other words, the third handle 170 is located on the side opposite to the second handle 60 with respect to the circular saw blade 35. As Figure 11 , 13 , as shown in 15, the third handle 170 extends linearly to the left from the left side surface of the upper edge portion of the fixed cover 33. In the present embodiment, in the front-rear direction, the third handle 170 is located at substantially the same position as the motor 41. The third handle 170 has a third gripping portion 171 that can be gripped by the user. In the present embodiment, the proximal end (right end) of the third handle 170 is screwed into a threaded hole formed in the fixed cover 33. That is, the third handle 170 can be detached. However, the third handle 170 can be connected to the fixed cover 33 in a non-detachable manner. In addition, the third handle 170 can be in any form. For example, it can be in the form of an annular handle like the first handle 50 or the second handle 60 instead of the straight rod handle form.

[0069] According to such a circular saw 110, the user can separately use the gripped handles according to the user's working posture. For example, the user can stand on the right side of the circular saw 110 and use the circular saw 110 by holding the first gripping portion 51 and the second gripping portion 61 with both hands respectively. Or, the user can stand on the left side of the circular saw 110 and use the circular saw 110 by holding the first gripping portion 51 and the third gripping portion 171 with both hands respectively. Moreover, according to the circular saw 110, since the second gripping portion 61 is located in front of the motor 41, the distance between the first gripping portion 51 and the second gripping portion 61 in the front-rear direction is increased. Therefore, when the user uses the circular saw 110 by holding the first gripping portion 51 and the second gripping portion 61 with both hands respectively, the circular saw 110 can be held more stably.

[0070] Moreover, in the circular saw 110, in a state where the circular saw blade 35 is orthogonal to the base 20 and the protruding distance of the circular saw blade 35 protruding toward the base 20 is the maximum, the protruding distance L10 of the circular saw blade 35 below the base 20 (refer to Figure 11) is 100 mm or more. According to this structure, compared with the existing circular saw, a work piece with a greater thickness can be cut. The protruding distance L10 can be 150 mm or more. In this way, a work piece with an even greater thickness can be cut. In the present embodiment, a protruding distance of 158 mm is disclosed as an example.

[0071] Moreover, in the circular saw 110, when the torque of the main shaft 46 is 5 N / m, the circumferential speed of the tip of the circular saw blade 35 is 32.4 m / s. At this time, the value obtained by multiplying the circumferential speed of the tip of the circular saw blade 35 by the diameter of the circular saw blade 35 (hereinafter, simply referred to as the product) is 0.415 m (= 415 mm) × 32.4 m / s = 13.4 m 2 / s. The larger the diameter of the circular saw blade 35, the closer it is to linear motion, so the power transmission loss becomes smaller, thereby increasing the cutting efficiency. Therefore, if this product is 6.0 m 2 / s, compared with the existing circular saw, the work piece can be cut efficiently. This product can be 10.0 m 2 / s or more. In this way, the cutting efficiency can be further improved.

[0072] Figure 17 Shows the difference in the product between the circular saw 110 and the existing circular saw. The straight line represented by the solid line corresponds to the circular saw 110 according to the present embodiment (the rated output of the battery 14 is 36 V, and the diameter of the circular saw blade 35 is 415 mm). The products when the torque of the main shaft 46 is 2, 7, and 10 N / m are plotted, and the result of obtaining its approximate straight line is shown. The straight line represented by the single-dot dash line corresponds to the existing circular saw (the rated output of the battery is 36 V, and the diameter of the circular saw blade is 165 mm). The products when the torque of the main shaft is 2 and 4 N / m are plotted, and the result of obtaining its approximate straight line is shown. The straight line represented by the double-dot dash line corresponds to the existing circular saw applying the technology described in Japanese Patent Laid-Open Publication No. 2020-116834 (the rated output of the battery is 18 V, and the diameter of the circular saw blade is 125 mm). The products when the torque of the main shaft is 1 and 2 N / m are plotted, and the result of obtaining its approximate straight line is shown. Generally, the circular saw is used in a state where the torque of the main shaft is about 4 to 7 N / m. Therefore, if the product when the torque of the main shaft 46 is 5 N / m is used as an index value, the cutting efficiency can be evaluated well.

[0073] Hereinafter, refer to Figure 18, regarding the third embodiment, only the points different from the second embodiment will be described. The only difference between the circular saw 210 according to the third embodiment and the second embodiment is the position of the third handle 170. Specifically, the third handle 170 is mounted on the fixed cover 33 at a position on the front side of the motor 41 (motor housing 11). The fixed cover 33 has a protruding portion 33a that protrudes upward at the mounting position of the third handle 170. By mounting the third handle 170 on this protruding portion 33a, the third handle 170 can be disposed outside the tip of the circular saw blade 35, and interference between the circular saw blade 35 and the third handle 170 can be avoided. According to this embodiment, the distance between the first gripping portion 51 and the third gripping portion 171 in the front-rear direction is made larger than that in the second embodiment. Therefore, when the user holds the circular saw 210 with both hands by gripping the first gripping portion 51 and the third gripping portion 171 respectively, the circular saw 210 can be held more stably.

[0074] As described above, several embodiments of the present invention have been described. However, the above embodiments are for the purpose of facilitating understanding of the present invention and do not limit the present invention. The present invention can be changed and improved without departing from its gist, and equivalents thereof are included in the present invention. In addition, within the scope of being able to solve at least a part of the above technical problems or achieve at least a part of the effects, the various elements described in the claims and the specification can be arbitrarily combined or omitted.

[0075] For example, each feature of the above-mentioned specifications of the circular saw 10 (such as the diameter of the circular saw blade, the circumferential speed of the circular saw blade, the force at the tip of the circular saw blade, the rated voltage of the battery 14, the reduction ratio of the reduction mechanism 43, etc.) and each feature of the various layouts of the circular saw 10 can be separated from other features and adopted separately.

[0076] Moreover, the above-mentioned specifications of the circular saw 10 are not limited to portable circular saws, and can also be applied to bench circular saws or sliding circular saws that use a battery as a power source.

[0077] The correspondence between the respective structural elements of the above-described embodiments and the respective structural elements of the present invention is shown below. However, each structural element of the embodiments is merely an example and does not limit the respective structural elements of the present invention. The circular saw 10 is an example of a "circular saw". The circular saw blade 35 is an example of a "circular saw blade". The electric motor 41 is an example of an "electric motor". The battery mounting portion 13 is an example of a "battery mounting portion". The battery 14 is an example of a "battery". The speed reduction mechanism 43 is an example of a "speed reduction mechanism". The first handle 50 is an example of a "first handle". The first gripping portion 51 is an example of a "first gripping portion". The second handle 60 is an example of a "second handle". The second gripping portion 61 is an example of a "second gripping portion". The front edge portion 52 is an example of a "front edge portion of the first gripping portion". The front edge portion 62 is an example of a "front edge portion of the second gripping portion". The first center point 53 is an example of a "first center point". The second center point 63 is an example of a "second center point". The center of gravity 15 is an example of a "first center of gravity". The main shaft 46 is an example of a "final output shaft".

Claims

1. A circular saw, characterized in that: It has a circular saw blade, a motor and a battery mounting portion, wherein: The circular saw blade is capable of rotating; The motor is used to provide a rotational driving force to the circular saw blade; The battery mounting portion is configured to detachably mount a battery for supplying electric power to the motor. The diameter of the circular saw blade is greater than or equal to 300 mm and less than or equal to 460 mm.

2. The circular saw according to claim 1, characterized in that The circular saw is configured such that the circular saw blade rotates at a peripheral speed of 70.0 m / s or less when no load is applied.

3. The circular saw according to claim 2, characterized in that The circular saw is configured such that the circular saw blade rotates at a peripheral speed of 50.0 m / s or less when no load is applied.

4. The circular saw according to any one of claims 1 to 3, characterized in that The circular saw is configured such that the circular saw blade rotates at a peripheral speed of 25.0 m / s or more when under load.

5. The circular saw according to claim 4, characterized in that The circular saw is configured such that the circular saw blade rotates at a peripheral speed of 28.0 m / s or more when under load.

6. The circular saw according to any one of claims 1 to 5, characterized in that The circular saw is configured to rotate so that the force of the blade edge of the circular saw blade when loaded is 20.0 N or more.

7. The circular saw according to claim 6, characterized in that The circular saw is configured to rotate so that the force of the blade edge of the circular saw blade when loaded is 30.0 N or more.

8. The circular saw according to any one of claims 1 to 7, characterized in that Having the battery, The rated voltage of the battery is 18V or more and 80V or less.

9. The circular saw according to any one of claims 1 to 7, characterized in that Having the battery, The rated voltage of the battery is 36V.

10. The circular saw according to any one of claims 1 to 9, characterized in that A speed reduction mechanism is provided, wherein the speed reduction mechanism is configured to reduce the speed of the rotational driving force of the motor and transmit the speed reduction force to the circular saw blade. The reduction ratio of the reduction mechanism is greater than 7.

11. The circular saw according to any one of claims 1 to 10, characterized in that The circular saw is a portable circular saw. The portable circular saw has a first handle and a second handle, wherein: The first handle has a first gripping portion; When the cutting direction of the portable circular saw is defined as the front side and the side opposite to the front side is defined as the rear side, the second handle is arranged on the front side of the first handle and has a second gripping portion. The battery mounting portion is configured such that, when the battery is mounted in the battery mounting portion, the entire battery is located between the front edge of the first gripping portion and the front edge of the second gripping portion in the front-rear direction.

12. The circular saw according to any one of claims 1 to 10, characterized in that The circular saw is a portable circular saw. The portable circular saw has a first handle and a second handle, wherein: The first handle has a first gripping portion; When the cutting direction of the portable circular saw is defined as the front side and the side opposite to the front side is defined as the rear side, the second handle is arranged on the front side of the first handle and has a second gripping portion. The center of gravity of the circular saw with the battery installed in the battery installation portion is located below the lower edge of the first grip and the lower edge of the second grip in the vertical direction of the posture when the portable circular saw is used.

13. The circular saw according to any one of claims 1 to 10, characterized in that The circular saw is a portable circular saw. The portable circular saw comprises a first handle, a second handle and the battery, wherein: The first handle has a first gripping portion; When the cutting direction of the portable circular saw is defined as the front side and the side opposite to the front side is defined as the rear side, the second handle is arranged on the front side of the first handle and has a second gripping portion. When the battery is mounted on the battery mounting portion, the center of gravity of the battery is located below the lower edge of the first grip and the lower edge of the second grip in the vertical direction of the posture when the portable circular saw is used.

14. The circular saw according to any one of claims 1 to 10, characterized in that The circular saw is a portable circular saw. The portable circular saw has a first handle and a second handle, wherein: The first handle has a first gripping portion; When the cutting direction of the portable circular saw is defined as the front side and the side opposite to the front side is defined as the rear side, the second handle is arranged on the front side of the first handle and has a second gripping portion. When the distance between the center point of the area of ​​the first gripping part in the front-to-back direction where the user actually holds the first gripping part, i.e., the first center point, and the center point of the second gripping part, i.e., the second center point, is set as L1, and the distance between the first center point in the front-to-back direction and the center of gravity of the circular saw when the battery is installed in the battery installation part, i.e., the first center of gravity, is set as L2, the value of L2 / L1 is greater than 0.5 and less than 0.

7.

15. The circular saw according to any one of claims 1 to 14, characterized in that The circular saw is a portable circular saw, A base is provided, wherein the base has a through hole through which the circular saw blade can pass. When the side of the motor relative to the base is defined as the upper side and the opposite side is defined as the lower side, when the circular saw blade is orthogonal to the base and the protrusion of the circular saw blade through the through hole toward the lower side relative to the base is the maximum, the protruding distance of the circular saw blade on the lower side is greater than 100 mm.

16. The circular saw according to claim 15, characterized in that When the circular saw blade is perpendicular to the base and the protrusion amount of the circular saw blade toward the lower side relative to the base after passing through the through hole is at a maximum, the protrusion distance of the circular saw blade toward the lower side is greater than 150 mm.

17. A circular saw, characterized in that: It has a circular saw blade, a motor, a final output shaft and a battery mounting portion, wherein: The circular saw blade is capable of rotating; The motor is used to provide a rotational driving force to the circular saw blade; The final output shaft is rotatable, used for transmitting the rotational driving force of the motor, and is mounted with the circular saw blade; The battery mounting portion is configured to detachably mount a battery for supplying electric power to the motor. When the torque of the final output shaft is 5 N / m, the value obtained by multiplying the peripheral speed of the blade tip of the circular saw blade by the diameter of the circular saw blade is 6.0 m / m. 2 / s or more.

18. The circular saw according to claim 17, characterized in that When the torque of the final output shaft is 5 N / m, the value obtained by multiplying the peripheral speed of the blade tip of the circular saw blade by the diameter of the circular saw blade is 10.0 m / m. 2 / s or more.

19. The circular saw according to claim 17 or 18, characterized in that The circular saw is a portable circular saw, A base is provided, wherein the base has a through hole through which the circular saw blade can pass. The side that makes the circular saw move forward when cutting the workpiece by the circular saw is defined as the front side, and the opposite direction is defined as the rear side, the side where the motor is located relative to the base is defined as the upper side, and the opposite side is defined as the lower side, the direction perpendicular to the front-to-back direction and the up-down direction is defined as the left-right direction, the right side when observing the front side from the rear side is defined as the right side, and the opposite side is defined as the left side, the circular saw blade is located on the left side relative to the motor.

20. The circular saw according to claim 19, characterized in that It has a first handle, a second handle and a third handle, wherein: The first handle has a first grip portion at least partially located at the rear side of the circular saw blade in the front-rear direction; The second handle has a second grip portion located on the front side of the motor in the front-rear direction and on the right side of the circular saw blade in the left-right direction; The third handle includes a third grip portion located on the left side of the circular saw blade in the left-right direction.

21. The circular saw according to claim 20, characterized in that The third gripping portion is located on the front side of the motor in the front-rear direction.

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