Cutting blade

Abstract

A cutting blade according to the present disclosure has: an inner surface on which a blade portion and a rising portion are formed, the rising portion being connected to a rear end of the blade portion and having a thickness that increases in the thickness direction; and an outer surface that connects a front end and a rear end of the inner surface. A first hole positioned rearward of the blade portion and a second hole positioned rearward of the first hole are formed. A region of the inner surface between a center of the first hole and the rear end of the blade portion includes an inner concave surface recessed in a direction approaching the outer surface, and a region of the outer surface between the center of the first hole and the rear end of the blade portion includes an outer concave surface recessed in a direction approaching the inner surface.

Description

Cutting blade

[0001] The present disclosure relates to a cutting blade attached to an electric rebar cutting device.

[0002] For example, an electric rebar cutting device as shown in Patent Document 1 below is known. In an electric rebar cutting device, instead of the user's gripping force, the cutting blade is operated by the driving force of an electric driving device typified by an electric motor or the like, and the object to be cut is cut by sandwiching it with a pair of cutting blades.

[0003] Japanese Patent Application Laid-Open No. 2021-171580

[0004] When an object to be cut is cut many times using such an electric rebar cutting device, a crack may occur in one of the pair of cutting blades and break. Depending on how the crack occurs, fragments of the broken cutting blade may enter the rebar cutting device, etc., and the normal operation of the rebar cutting device may be hindered.

[0005] Therefore, an object of the present disclosure is to provide a cutting blade capable of suppressing the scattering of broken fragments.

[0006] The present application discloses a cutting blade attached to an electric rebar cutting device. This cutting blade has a blade portion extending in a first direction, an inner surface formed with a rising portion that is connected to the rear end of the blade portion in the first direction and whose thickness increases in a thickness direction perpendicular to the first direction, and an outer surface connecting the front end and the rear end of the inner surface. A first hole located behind the blade portion with respect to the first direction and a second hole located behind the first hole are formed. In such a cutting blade, a region of the inner surface between the center of the first hole and the rear end of the blade portion in the first direction includes an inner concave surface that depresses in a direction approaching the outer surface, and a region of the outer surface between the center of the first hole and the rear end of the blade portion in the first direction includes an outer concave surface that depresses in a direction approaching the inner surface.

[0007] Here, the cutting blade according to the present application may be provided in a state of being attached to an electric rebar cutting device in advance, or may be provided as a replacement blade for a rebar cutting device in which the cutting blade is damaged or worn.

[0008] Furthermore, this application discloses a pair of cutting blades for cutting reinforcing bars by being attached to an electric reinforcing bar cutting device comprising an electric motor, a movable member configured to be movable in the front-rear direction by the electric motor, a pair of links connected to the movable member that open in a direction that increases the angle when the movable member moves forward and close in a direction that decreases the angle when the movable member moves backward, a pair of pins for providing a rotation axis, a shaft member positioned in front of the movable member, and a pair of guide members.Each of these cutting blades has an inner surface formed with a blade portion extending in a first direction and a cut-off portion that connects to the rear end of the blade portion in the first direction and whose thickness increases in a thickness direction perpendicular to the first direction, and an outer surface that connects the front end and rear end of the inner surface, and a first hole for inserting the pins, located behind the blade portion with respect to the first direction, and a second hole located behind the first hole for connecting to the end of the links, respectively. In such a cutting blade, the region of the inner surface between the center of the first hole and the rear end of the blade portion in the first direction in the first direction each includes an inner concave surface that is recessed in a direction approaching the outer surface and is formed to face the shaft member when the pair of cutting blades are close to each other, and the region of the outer surface between the center of the first hole and the rear end of the blade portion in the first direction in the first direction each includes an outer concave surface that is recessed in a direction approaching the inner surface and is formed to allow the guide member to enter when the cutting blade moves.

[0009] According to this disclosure, it is possible to provide a cutting blade that can suppress the scattering of fractured fragments.

[0010] Figure 1A is a plan view of a cutting blade according to one embodiment. Figure 1B is a front view of a cutting blade according to one embodiment. Figure 1C is a rear view of a cutting blade according to one embodiment. Figure 1D is a cross-sectional view of a cutting blade according to one embodiment. Figure 2A is a cross-sectional view of a rebar cutting device according to one embodiment. Figure 2B is a cross-sectional view of a rebar cutting device according to one embodiment. Figure 3A is a perspective view showing a modified example of a cutting blade according to one embodiment. Figure 3B is a perspective view showing a modified example of a cutting blade according to one embodiment. Figure 3C is a perspective view showing a modified example of a cutting blade according to one embodiment. Figure 4 is a plan view showing a modified example of a cutting blade according to one embodiment.

[0011] The embodiments of this disclosure will be described below with reference to the drawings. The embodiments described below are illustrative examples for illustrating this disclosure and are not intended to limit this disclosure to these embodiments only.

[0012] [First Embodiment] [Configuration of the Cutting Blade] Figures 1A, 1B, and 1C are a plan view, a front view, and a rear view of the cutting blade B according to this embodiment. Figure 1D is a cross-sectional view taken along the line X-X in Figure 1C, and corresponds to a cross-sectional view obtained by cutting the cutting blade B with a virtual plane passing through the center in the thickness direction.

[0013] For convenience, the left direction in Figure 1A is sometimes referred to as the front X1 (or "front direction X1"), the opposite right direction is sometimes referred to as the rear X2 (or "rear direction X2"), and both directions are sometimes collectively referred to as the front-rear direction X. Similarly, the bottom direction in Figure 1A is sometimes referred to as the left Y1, the opposite top direction is sometimes referred to as the right Y2, and both directions are sometimes referred to as the left-right direction Y. In addition, the top direction in Figure 1B is sometimes referred to as the up Z1, the opposite bottom direction is sometimes referred to as the down Z2, and both directions are sometimes referred to as the up-down direction Z, etc. In this embodiment, the front-rear direction X corresponds to the direction in which the cutting edge CE of the cutting blade B extends, the up-down direction Z corresponds to the thickness direction of the cutting blade B, and the left-right direction Y corresponds to the width direction of the cutting blade B.

[0014] The cutting blade B according to this embodiment comprises a cutting edge CE (an example of a "blade portion") formed on the inside of the front end and an extension portion EP provided rearward X2 from the cutting edge CE. A first through hole H1 (an example of a "first hole") is formed in the region between the cutting edge CE and the extension portion EP of the cutting blade B, and a second through hole H2 (an example of a "second hole") is formed at the rear end of the extension portion EP of the cutting blade B, also passing through the cutting blade B. However, the first through hole H1 and the second through hole H2 may be formed as notches communicating with the inner surface IS or outer surface OS, which will be described later. Furthermore, as will be described later, the portion that engages with the rebar cutting device is not necessarily limited to the first through hole H1 and the second through hole H2 that penetrate the cutting blade B in the thickness direction.

[0015] As described later, the electric rebar cutting device of this embodiment is configured to be able to attach a pair of cutting blades B using pins PN1 and PN2 which are inserted through the first through-hole H1 and the second through-hole H2, respectively. This rebar cutting device is configured to be able to open and close a pair of cutting blades CE by rotating the rear end of the cutting blade B relative to the pin PN1 inserted through the first through-hole H1 via the pin PN2 inserted through the second through-hole H2, and is configured to be able to cut the rebar to be cut by clamping it with the cutting blades CE of the pair of cutting blades B. Furthermore, if one of the cutting blades B is damaged or worn, it is possible to remove the damaged cutting blade B by removing pins PN1 and PN2 and attach a new cutting blade B to the rebar cutting device.

[0016] As shown in Figure 1A, etc., the cutting blade B according to this embodiment comprises a cutting edge CE formed on the inside of the front end and an extension portion EP provided rearward X2 from the cutting edge CE, and is formed in a plate shape having a first end face US facing upward Z1, a second end face LS facing downward Z2, and a side surface connecting the first end face US and the second end face LS. Of these side surfaces, there is an inner surface IS on which the cutting edge CE is formed and an outer surface OS formed on the opposite side of the inner surface IS. In this embodiment, the inner surface IS corresponds to the side facing left Y1, and the outer surface OS corresponds to the side facing right Y2, and the inner surface IS and the outer surface OS are connected to each other at both ends. However, the inner surface IS and the outer surface OS do not necessarily have to be directly connected, and the cutting blade B may be provided between the inner surface IS and the outer surface OS and connected via a connection surface different from the inner surface IS and the outer surface OS. For example, as described later, the cutting blade B may be configured such that the inner surface IS and the outer surface OS are connected via the inner surface of the second through hole H2 by forming the second through hole H2 as a notch that connects to the inner surface IS and / or the outer surface OS.

[0017] A cutting edge (CE) is formed on the front end portion of the inner surface IS. The cutting edge CE is the part that contacts the reinforcing bar to be cut and cuts the reinforcing bar by sandwiching it with the cutting edge CE of the other cutting blade B.

[0018] In this embodiment, the cutting edge CE is formed to extend in the front-rear direction X (an example of the "first direction"). By forming such cutting edges CE on each of the pair of cutting blades B, it becomes possible to cut the reinforcing bar whether the rear end portion or the front end portion of the cutting edge CE is used.

[0019] The cutting blade CE can employ the configuration shown in this embodiment or other known configurations. In this embodiment, in a cross-sectional view obtained by cutting with a virtual plane perpendicular to the front-rear direction X, the cutting blade CE is formed such that its thickness in the vertical direction Z decreases as it progresses inward (to the tip) at the left Y1. Furthermore, as shown in Figure 1B and the like, in this embodiment, the cutting blade B, which includes the cutting blade CE, the cutting edge RP, the inner concave surface IC, and the outer concave surface OC, is formed symmetrically above and below with respect to a virtual plane passing through the center in the thickness direction (vertical direction Z). Therefore, the cutting blade CE has two blades facing upward Z1 and downward Z2, and the tip where the two blades connect is located on the virtual plane passing through the center in the thickness direction (vertical direction Z) of the cutting blade B. With such a configuration, it is possible to cut reinforcing bars by attaching a pair of cutting blades B of the same structure to a reinforcing bar cutting device.

[0020] However, the cutting blade B does not necessarily have to be formed symmetrically vertically. For example, the cutting blade may be single-edged, or at least the cutting edge CE, the cutting edge RP, the inner concave surface IC, and the outer concave surface OC may be formed symmetrically vertically, while other parts may be formed asymmetrically vertically.

[0021] The inner surface IS further has a cut-up portion RP which connects to the rear end of the cutting edge CE in the front-rear direction X and increases in thickness in the vertical direction Z. The cut-up portion RP in this embodiment is a portion having an inner surface defined by a ridge that connects to the rear end of the cutting edge CE located at the center in the thickness direction and extends upward Z1 to connect to the first end face US at the upper end, and a ridge that connects to the rear end of the cutting edge CE and extends downward Z2 to connect to the second end face LS at the lower end.

[0022] As shown in Figure 1A and other figures, a portion of the inner surface IS, including the cut-off portion RP, extends in the front-rear direction X and includes an inner concave surface IC that is recessed in a direction approaching the outer surface OS relative to the first virtual straight line L1 passing through the tip of the cutting edge CE. The structure of the inner concave surface IC will be described later.

[0023] The inner surface IS further includes the inner surface of the extension EP, which is provided rearward X2 from the cutting edge CE and the inner concave surface IC. In this embodiment, the extension EP extends to the right Y2 as it progresses rearward X2, and is formed to extend diagonally rearward, away from the first virtual straight line L1 that passes through the tip of the cutting edge CE. Therefore, the inner surface IS includes a substantially flat plane that connects to the rear end of the inner concave surface IC and extends diagonally rearward, away from the first virtual straight line L1.

[0024] The outer surface OS is formed to connect the front end and rear end of the inner surface IS.

[0025] As shown in Figure 1C and other figures, a portion of the outer surface OS includes an outer concave surface OC that is formed by being recessed in the direction approaching the inner surface IS. The structure of the outer concave surface OC will be described later.

[0026] As described above, a first through-hole H1 is formed behind the cutting edge CE of the cutting blade B, and a second through-hole H2 is formed behind the first through-hole H1. As will be described later, the second through-hole H2 corresponds to the part through which a pin PN2 is inserted to transmit the driving force for opening and closing the cutting blade B by connecting to the link of the rebar cutting device. The first through-hole H1 corresponds to the part through which a pin PN1, which serves as the rotation axis for opening and closing the cutting blade B, is inserted.

[0027] Therefore, the second through-hole H2 may be formed as part of a connection portion consisting of a known configuration for connecting to a link or the like of a rebar cutting device in order to open and close the cutting blade B. For example, instead of the configuration shown in this embodiment, the second through-hole H2 may be formed as a notch communicating with the inner surface IS or outer surface OS described later, or it may be formed in a polygonal shape. In this case, the center C2 of the second through-hole H2 is the center of a circle that approximates the second through-hole H2 in a known manner. Alternatively, instead of the second through-hole H2, the cutting blade B may be connected to a link or the like of a rebar cutting device by forming a hole (a recess that is recessed in the thickness direction from the first end face US or second end face LS of the cutting blade B) that does not penetrate the cutting blade B in the thickness direction (vertical direction Z).

[0028] Similarly, the first through-hole H1 may be formed as part of an engagement portion consisting of a known configuration for engaging with a portion of the rebar cutting device that serves as a rotation axis for opening and closing the cutting blade B. For example, instead of the configuration shown in this embodiment, the first through-hole H1 may be formed as a notch communicating with the inner surface IS or outer surface OS described later, or it may be formed in a polygonal shape. In this case, the center C1 of the first through-hole H1 is the center of a circle that approximates the first through-hole H1 in a known manner. Alternatively, instead of the first through-hole H1, the cutting blade B may be engaged with a component or part of the rebar cutting device such as a pin by forming a hole (a recess that is recessed in the thickness direction from the first end face US or second end face LS of the cutting blade B) that does not penetrate the cutting blade B in the thickness direction (vertical direction Z).

[0029] [Configuration of the inner and outer concave surfaces] When cutting an object, a force to close the cutting blade is applied to the rear end of the cutting blade via a pin inserted through the second through-hole from the rebar cutting device, while the cutting edge of the cutting blade receives a large reaction force from the object being cut. As a result, a large bending moment is generated in the middle portion of the outer surface of the cutting blade in the front-to-back direction. The inventors of this application have focused on the fact that if a crack formed near the cutting edge on the inner front end of the cutting blade extends far to the outer rear end of the cutting blade, the fragments of the broken cutting blade can be scattered by rotating outward due to the large bending moment.

[0030] Furthermore, the inventors of this application have noted that there is variability in how cracks form, and in some cases, short cracks may occur from the inner surface adjacent to the first through-hole to the first through-hole, rendering the cutting blade unusable. In addition, if the user continues to use the rebar cutting device without noticing such short cracks, the cracked and damaged cutting blade of the pair will not receive the reaction force from the material being cut, while only the cutting blade without cracks will receive the reaction force. As a result, a large, biased reaction force in the lateral direction will act on the forward-backward moving member, which is designed on the premise of canceling out the lateral components of the reaction forces from the pair of cutting blades, potentially leading to damage to the components of the rebar cutting device.

[0031] Therefore, the inventors of this application conceived a configuration in which, in order to increase rigidity and make it difficult for cracks to form, an inner concave surface IC and an outer concave surface OC are formed on the inner surface IS and outer surface OS of the cutting blade B, respectively, where the width in the left-right direction Y should be secured as much as possible, and the rigidity of the region in which the inner concave surface IC and outer concave surface OC are formed is deliberately reduced. Cracks tend to extend to connect the inner concave surface IC (or its surroundings) and the outer concave surface OC (or its surroundings), which are provided so as to have less rigidity compared to the surroundings, so it is possible to suppress the frequency in which cracks extend far to the rear end of the outer surface OS of the cutting blade B.

[0032] Here, the inner concave surface IC is formed at least in the region of the inner surface IS between the center C1 of the first through hole H1 in the front-rear direction X and the position P5 corresponding to the rear end of the cutting edge CE, and the outer concave surface OC is formed at least in the region of the outer surface OS between the center C1 of the first through hole H1 in the front-rear direction X and the position P5 corresponding to the rear end of the cutting edge CE. Therefore, it is possible to suppress the frequency of short cracks that reach the first through hole H1 from the inner surface IS adjacent to the first through hole H1.

[0033] Furthermore, because the variation in how cracks form is suppressed, users are more likely to notice them. Therefore, it becomes possible to prevent situations where cracks are not noticed and the rebar cutting device is used, leading to damage to the parts.

[0034] The inner concave surface IC formed on the inner surface IS is formed in a region between position P2, which corresponds to the center C1 of the first through hole H1 in the front-rear direction X, and position P5, which corresponds to the rear end of the cutting edge CE. In this embodiment, the inner concave surface IC is formed in a region between position P3, which corresponds to a position X1 forward of position P2, and position P5 (where P5 > P3 > P2 is the relationship in a coordinate system with the front direction X1 as the axis).

[0035] With this configuration, it is possible to suppress the occurrence of cracks on the inner surface IS caused by the reaction force received by the cutting edge CE from the workpiece during cutting, from a region X2 behind position P3 in the front-rear direction X where the relative distance from the cutting edge CE is greater and rigidity is high, and to increase the possibility of cracks occurring from the inner concave surface IC, which is relatively close to the cutting edge CE and has less rigidity. Here, at least a part of the inner concave surface IC is formed in a region X1 forward of position P2, which corresponds to the center C1 of the first through hole H1 in the front-rear direction X, so it is possible to suppress the occurrence of cracks that reach the first through hole H1.

[0036] In addition, in this embodiment, the inner concave surface IC is formed only in the region X1 forward of position P2 in the front-rear direction X.

[0037] With this configuration, the rigidity of the region near position P2, which is close to the first through-hole H1 in the front-rear direction X of the inner surface IS, can be increased. This makes it possible to further suppress the occurrence of cracks that originate from the inner surface near position P2 and reach the adjacent first through-hole H1.

[0038] Furthermore, the inner concave surface IC of this embodiment is provided to include the inner surface IS on which the cut-off portion RP is formed.

[0039] With this configuration, since it connects to the rear end of the cutting edge CE, it becomes possible to promote the generation of cracks from the cutting edge RP where large stresses occur.

[0040] In this embodiment, the inner concave surface IC is connected to the first end face US and the second end face LS. In other words, the magnitude of the inner concave surface IC in the vertical direction Z (or, if the magnitude of the inner concave surface IC in the vertical direction Z varies, the maximum value of the magnitude of the inner concave surface IC in the vertical direction Z) is the same as the thickness T1 of the cutting blade B.

[0041] According to such a configuration, it is possible to reduce the rigidity as compared with the case where the inner concave surface IC is formed only on a part of the inner surface IS in the vertical direction Z. Therefore, it is possible to increase the possibility that cracks occur from the inner concave surface IC. However, the inner concave surface IC may be formed only on a part of the inner surface IS in the vertical direction Z (for example, like the outer concave surface OC). In other words, the size of the inner concave surface IC in the vertical direction Z (when the size of the inner concave surface IC in the vertical direction Z varies, the maximum value of the size of the inner concave surface IC in the vertical direction Z) may be smaller than the thickness T1 of the cutting edge.

[0042] In addition, the inner concave surface IC of the present embodiment is formed to be curved when viewed from the thickness direction (vertical direction Z) (FIG. 1D, etc.).

[0043] According to such a configuration, it is possible to suppress the situation where the rigidity of a part of the inner concave surface IC is extremely smaller than the rigidity of other parts. Therefore, it is possible to suppress the situation where cracks easily enter the cutting edge B.

[0044] Here, the inner concave surface IC may be formed such that the central axis of the second virtual cylindrical surface CY2 including or approximating the inner concave surface IC is located at a position separated to the left Y1 from the cutting edge B.

[0045] According to such a configuration, it is possible to suppress the situation where the rigidity becomes extremely small due to the radius of curvature of the inner concave surface IC being too small. Therefore, it is possible to suppress the situation where cracks easily enter the cutting edge B.

[0046] However, (for example, like the outer concave surface OC), the inner concave surface IC may be formed in a shape other than curved (including an arc) when viewed from the thickness direction (vertical direction Z). For example, when cut by a virtual plane perpendicular to the vertical direction Z, the inner concave surface IC may be formed to have a rectangular or other polygonal cross-section.

[0047] On the other hand, the outer concave surface OC formed on the outer surface OS is at least formed in a region between a position P2 corresponding to the center C1 of the first through hole H1 in the front-rear direction X and a position P5 corresponding to the rear end of the cutting edge CE. In the present embodiment, the outer surface OS includes a concave surface that is recessed in a direction approaching the inner surface IS in a region between a position P1, which is behind X2 from the position P2, and a position P4, which is in front X1 from the position P2. That is, the region from the position P2 to the position P4 of the outer surface OS includes the outer concave surface OC, and the region from the position P1 to the position P2 includes the second outer concave surface 2OC that connects to the outer concave surface OC (in a coordinate system with the forward direction X1 as the axis, P5 > P4 > P3 > P2 > P1).

[0048] According to such a configuration, at least a part of the inner concave surface IC and at least a part of the outer concave surface OC are both formed in the regions of the inner surface IS and the outer surface OS between the position P2 and the position P5 in the front-rear direction X, so that it becomes possible to promote the generation of cracks that connect the inner concave surface IC and the outer concave surface OC.

[0049] Particularly in the present embodiment, the region from the position P3 to the position P5 corresponding to the region in the front-rear direction X where the inner concave surface IC is provided on the inner surface IS and the region from the position P2 to the position P4 corresponding to the region in the front-rear direction X where the outer concave surface OC is provided on the outer surface OS overlap in the region from the position P3 to the position P4. This is an example of "the region in the first direction where the inner concave surface is provided and the region in the first direction where the outer concave surface is provided overlap at least partially in the width direction perpendicular to the first direction and the thickness direction".

[0050] Therefore, it becomes possible to further promote the generation of cracks that connect the inner concave surface IC and the outer concave surface OC.

[0051] In the region from the position P3 to the position P4, when the radius of the first through hole H1 is R1, the region from the position (P2 + R1) to the position P4 in the front-rear direction X corresponds to a region in front X1 of the region where the first through hole H1 is formed in the front-rear direction X.

[0052] In this configuration, an inner concave surface IC and an outer concave surface OC are provided in a region X1 forward of the region where the first through-hole H1 is formed in the front-rear direction X. This configuration further reduces the possibility of cracks reaching the first through-hole H1. Preferably, the region in the front-rear direction X where the inner concave surface IC is provided and the region in the front-rear direction X where the outer concave surface OC is provided overlap at least partially. This is an example of "the region in the first direction where the inner concave surface is provided and the region in the first direction where the outer concave surface is provided overlap at least partially in the width direction perpendicular to the first direction and the thickness direction, forward of the region where the first hole is formed in the first direction."

[0053] Furthermore, it is preferable that the outer concave surface OC is formed such that its central axis is the center C1 of the first through hole H1, and it intersects with the first virtual cylindrical surface CY1 which is in contact with the inner surface IS.

[0054] With this configuration, since the outer concave surface OC is formed to extend to an area adjacent to the first through hole H1, it is possible to suppress cracks from reaching the first through hole H1 and promote cracks from reaching the outer concave surface OC.

[0055] On the other hand, it is preferable that the inner concave surface IC is formed so as not to intersect with the first virtual cylindrical surface CY1, but to be separated from the first virtual cylindrical surface CY1, or to be in contact with the first virtual cylindrical surface CY1.

[0056] With this configuration, it is possible to maintain the rigidity of the region inside the central axis (to the left, Y1) within the area enclosed by the first virtual cylindrical surface CY1, thereby suppressing the occurrence of cracks that reach the first through hole from the inner concave surface IC.

[0057] In this way, by separating the inner concave surface IC where cracks occur from the first through-hole H1, and bringing the outer concave surface OC, which can be reached by cracks extending from the inner concave surface IC, closer to the first through-hole H1, it becomes possible to promote the occurrence of cracks connecting the inner concave surface IC (or its surroundings) and the outer concave surface OC (or its surroundings).

[0058] In this embodiment, the outer concave surface OC is formed so as not to connect to either the first end face US or the second end face LS. In other words, the size T2 of the outer concave surface OC in the vertical direction Z (or, if the size Z of the outer concave surface OC varies, the maximum value T2 of the size Z of the outer concave surface OC in the vertical direction Z) may be smaller than the thickness T1 of the cutting blade B. In other words, the outer concave surface OC is formed to be recessed with respect to the outer surface OS located at the front X1 and rear X2, respectively, and also recessed with respect to the outer surface OS located at the upper Z1 and lower Z2, respectively.

[0059] With this configuration, it is possible to suppress the possibility that a crack extending from the inner surface IS and reaching the outer concave surface OC will extend to the first end face US and the second end face LS and cause separation. Therefore, it is possible to suppress the possibility that a part of the cutting blade B will be completely severed and scattered by the crack.

[0060] However, in order to reduce rigidity and increase the probability of cracks reaching the outer concave surface OC, it is preferable that the magnitude T2 of the vertical Z of the outer concave surface OC (or the maximum value T2 of the vertical Z of the outer concave surface OC if the magnitude Z of the outer concave surface OC fluctuates) is one-third or more of the thickness T1 of the cutting blade B (or the maximum value T1 of the vertical Z of the cutting blade B if the magnitude Z of the cutting blade B fluctuates).

[0061] However, the outer concave surface OC is not limited to the configuration shown in this embodiment, and may be formed to connect to either the first end face US or the second end face LS, or to connect to both the first end face US and the second end face LS (in the latter case, the size T2 of the outer concave surface OC in the vertical direction Z (if the size Z of the outer concave surface OC varies, the maximum value T2 of the size Z of the outer concave surface OC in the vertical direction Z) is the same as the thickness T1 of the cutting blade B). Similarly, the inner concave surface IC is not limited to the configuration shown in this embodiment, nor is it limited to a configuration in which it is recessed relative to the inner surfaces IS located at the front X1 and rear X2, respectively, and modifications in this respect will be described later.

[0062] Furthermore, the cut-up portion RP may be formed such that its entirety is included in the region between a position P3 corresponding to a position X1 forward of a position P2 corresponding to the center C1 of the first through hole H1 and a position P5 corresponding to the rear end of the cutting edge CE. This is an example of "the cut-up portion being formed such that its entirety is included in the region between a position forward of the center of the first hole in the first direction and the rear end of the cutting edge in the first direction."

[0063] [Configuration of the rebar cutting device] Below, we will describe the configuration of an example of a rebar cutting device to which the cutting blade B shown in this embodiment can be attached.

[0064] Figure 2A is a cross-sectional view showing the cutting edges CE of a pair of cutting blades B of the rebar cutting device 10 according to this embodiment in an open state, and Figure 2B is a partially enlarged view of the front end of the cross-sectional view showing the cutting edges CE of a pair of cutting blades B of the rebar cutting device 10 in a closed state. The extension direction (extension direction; left-right direction on the paper in Figures 2A and 2B) of the cutting edges CE of the cutting blade B in the closed state (Figure 2B) will be described as the front-back direction X.

[0065] The rebar cutting device 10 is an electrically operated cutting device configured for cutting rebar at construction sites and the like. The configuration of the rebar cutting device 10 will be described with reference mainly to Figure 2A. The rebar cutting device 10 comprises a housing 11, a trigger switch 12, a cutting mechanism 100, a ball screw 200, a reduction gear 300, an electric motor 400, a control board, and a storage battery 600.

[0066] The housing 11 is a container that demarcates the outer shape of the rebar cutting device 10 and is made of, for example, resin. Inside the housing 11 are the ball screw 200 and the reducer 300, which will be described later. In Figure 2A, the portion of the housing 11 on the near side of the paper has been removed, and the internal structure of the rebar cutting device 10 is shown as a cross-sectional view.

[0067] The trigger switch 12 is a switch operated by the user's finger. The user can turn the trigger switch 12 ON by placing their finger on the trigger switch 12 and pulling it towards them. When the user releases their grip, the trigger switch 12 returns to its original position due to the force of a spring, turning it OFF. When the trigger switch 12 is switched between the ON and OFF states, a corresponding signal is sent to the control board, which will be described later. The trigger switch 12 is an operating part that can be switched between the ON and OFF states by the user's operation. As will be explained later, when the user switches the trigger switch 12 to the ON state, the cutting of the reinforcing bars begins.

[0068] The cutting mechanism 100 is the part that cuts the reinforcing bar, which is the object to be cut. The cutting mechanism 100 has a pair of cutting blades B (sometimes called "blade members B") and a pair of link members 120. Of the pair of cutting blades B, the cutting blade B located at the top of the paper in Figure 2A (sometimes called "left Y1") is sometimes referred to as cutting blade BU, and the cutting blade B located at the bottom of the paper (sometimes called "right Y2") is sometimes referred to as cutting blade BL.

[0069] The configuration of the pair of cutting blades B is as described above, so the explanation will be omitted or simplified below. Each cutting blade B has a cutting edge CE formed on it that grips and cuts the object to be cut. A cylindrical pin PN1, which is fixed to the housing 11 (including parts such as the main frame fixed to the housing 11), is inserted through the first through hole H1 of the pair of cutting blades B. The pin PN1 serves as the rotation axis of the cutting blade B. For this reason, the pair of cutting blades B are held in a state where they can rotate around the axis of the pin PN1. In this embodiment, each cutting blade B is positioned opposite to another such that the edges of the cutting edges CE operate on a trajectory that passes through approximately the same XY plane. This makes it possible to switch between an open state in which the cutting edges CE are spaced apart from each other and a closed state in which the cutting edges CE are in contact with (or close to) each other. In Figure 2A, the pair of cutting edges CE are in the open state, and in Figure 2B, the pair of cutting edges CE are in the closed state.

[0070] The link member 120 (an example of a "link") is a rod-shaped member (rigid body) with a cylindrical axial pin PN2 formed at one end. The link member 120 is connected to the cutting blade B via the pin PN2 by inserting the pin PN2 of the link member 120 into the second through hole H2 of the cutting blade B. The other end of the link member 120 is connected to the connecting member 230, which will be described later, via the shaft 231. The link member 120 and the cutting blade B are connected in a manner that allows them to rotate freely with respect to each other around the pin PN2. Similarly, the link member 120 and the connecting member 230 are connected in a manner that allows them to rotate freely with respect to each other around the shaft 231. As will be explained later, the connecting member 230 moves in the left-right direction (front-back direction X) of Figure 2A by the driving force of the electric motor 400.

[0071] With the above configuration, the cutting blade B can be attached to the rebar cutting device 10 by inserting pins PN1 and PN2 into the first through-hole H1 and the second through-hole H2, respectively, and the cutting blade B can be removed from the rebar cutting device 10 by pulling out pins PN1 and PN2 from the first through-hole H1 and the second through-hole H2, respectively. Therefore, the user can replace the cutting blade B if it is damaged or otherwise damaged.

[0072] Pins PN1 and PN2 may be fixed to the housing 11 of the rebar cutting device 10, but they may also be composed of parts that are separable from the rebar cutting device 10. For example, pin PN1 may be composed of a male screw or the like, and when attaching the cutting blade B, the male screw may be inserted through the first through hole H1 and screwed into a female screw provided in the housing 11 of the rebar cutting device 10, thereby enabling the cutting blade B to be held rotatably. Similarly, pin PN2 may also be composed of a part that is separable from the rebar cutting device 10, and other known configurations for connecting the link member 120 and the cutting blade B may be adopted. For example, a hole with a female screw may be provided in the cutting blade B, and the link member 120 and the cutting blade B may be connected using a male screw (an example of a "pin") that is inserted through a through hole formed in the link member 120 and screwed into this female screw.

[0073] When the connecting member 230 moves to the left from the closed state shown in Figure 2B, the upper cutting blade BU in Figure 2B rotates counterclockwise, and the lower cutting blade BL in Figure 2B rotates clockwise. As a result, the pair of cutting blades CE move from the closed state to the open state. On the other hand, when the pair of cutting blades CE shown in Figure 2A are in the open state, when the connecting member 230 moves to the right in Figure 2A, the upper cutting blade BU in Figure 2A rotates clockwise, and the lower cutting blade BL in Figure 2A rotates counterclockwise. As a result, the pair of cutting blades CE return to the closed state. In this way, the pair of cutting blades B, the pair of link members 120, and the connecting member 230 as a whole constitute a so-called "toggle link mechanism".

[0074] The rebar cutting device 10 of this embodiment further includes a pair of guide plates 700 provided near the cutting edge CE of the cutting blade B. The guide plates 700 are plate-shaped members made of metal and are positioned to sandwich the cutting blade B from both the front and back sides of the paper in Figure 2A. The shape of the pair of guide plates 700 is identical to that of the other. Each guide plate 700 has a recess formed at the center of the left-right direction Y, which is recessed to the rear X2 (for convenience of explanation, the right side in Figure 2A may be referred to as the "front end side" below, and the left side in the same figure may be referred to as the "rear end side" below). The guide plates 700 have both the function of covering and protecting the cutting edge CE in the standby state, and the function of guiding the rebar to be cut along the recess to the space between the pair of cutting edges CE. The guide plates 700 also have the function of stabilizing the posture of the rebar cutting device 10 before and after cutting by sandwiching the rebar in the recess. Because the guide plate 700 partially obscures the cutting blade B, crack detection may be delayed.

[0075] The rebar cutting device 10 of this embodiment further includes a pair of guide members 130 for guiding the rotation of a pair of cutting blades B, and a shaft member 140 positioned X1 in front of the movable members, the nut 220 and the connecting member 230.

[0076] As described above, in this embodiment, each cutting blade B is rotatably supported by inserting a pin PN1, which serves as the axis of rotation, into the first through hole H1, such that the ridge of the cutting edge of the cutting blade CE passes through a trajectory that passes through approximately the same XY plane. However, if a large gap is provided between the outer diameter of the pin PN1 and the inner diameter of the first through hole H1 in order to allow the user to easily replace the cutting blade B, the axis of rotation may tilt from the vertical Z direction, and the trajectory of the cutting blade CE may deviate from the intended plane.

[0077] Therefore, the guide member 130 is provided to prevent the rotation axis of the cutting blade B from tilting significantly from the vertical direction Z by entering the outer concave surface OC when the cutting blade B rotates.

[0078] For example, when the pair of cutting blades CE are separated (open state), a part of the guide member 130 enters the outer concave surface OC (Figure 2A), and the guide member 130 in this embodiment is arranged such that as the pair of cutting blades CE get closer, more of the guide member 130 enters the outer concave surface OC (Figure 2B).

[0079] With this configuration, by appropriately shaping and forming the guide member 130, it becomes possible to suppress the situation in which the cutting blade B tilts when it moves.

[0080] Furthermore, the inventors of this application also focused on the fact that, due to misalignment of the mounting position during replacement, the distance between the pair of cutting blades B may become closer than expected, which could result in the pair of cutting blades CE colliding and being damaged during cutting. Therefore, they conceived of a configuration in which the shaft member 140 is placed in the region surrounded by the pair of inner concave surfaces IC when the pair of cutting blades B are close to each other.

[0081] With this configuration, the shaft member 140 acts as a spacer, making it possible to prevent the pair of cutting blades B from being closer together than intended. In addition, it is possible to prevent chips and other debris generated during the cutting of the workpiece from entering the area surrounded by the inner concave surfaces IC of the pair of cutting blades B. Here, the shaft member 140 may be provided with a protective portion formed above Z1 the area surrounded by the inner concave surfaces IC of the pair of cutting blades B, so as to cover part or all of the area surrounded by the inner concave surfaces IC of the pair of cutting blades B.

[0082] The ball screw 200 is a device that converts the rotational motion of the electric motor 400 into the linear motion of the connecting member 230, thereby operating the cutting mechanism 100. The ball screw 200 has a screw shaft 210, a nut 220, and a connecting member 230.

[0083] The screw shaft 210 is a rod-shaped member that extends linearly in the front-rear direction X from the rear end to the front end. A male screw is formed on the outer surface of the screw shaft 210. When the electric motor 400 is driven, the screw shaft 210 rotates around its central axis.

[0084] The nut 220 is a substantially cylindrical member positioned to surround the screw shaft 210 from the outer circumference. A female thread is formed on the inner surface of the nut 220, which screws onto a male thread formed on the outer surface of the screw shaft 210. The nut 220 is allowed to move along the longitudinal direction of the screw shaft 210, but its rotation around the central axis of the screw shaft 210 is restricted. Therefore, when the screw shaft 210 rotates around its central axis, the nut 220 moves along that central axis in the left-right direction as shown in Figure 2A.

[0085] The connecting member 230 is a member attached to the nut 220 and moves along the screw shaft 210 together with the nut 220. The connecting member 230 is attached so as to protrude toward the tip side from the nut 220. A pair of link members 120 are connected to the portion of the connecting member 230 near the tip end via the shaft 231 mentioned earlier. When the nut 220 and the connecting member 230 move forward X1, the pair of link members 120 open in a direction that increases the angle, and when they move backward X2, they close in a direction that decreases the angle.

[0086] A magnet is attached to the outer surface of the connecting member 230. A Hall sensor is also attached to the housing 11 in the vicinity of the connecting member 230. The position of the Hall sensor is such that when the nut 220 moves to the rear end from the state shown in Figure 2B and the cutting edge CE is fully open, it faces the magnet on the connecting member 230. When the cutting edge CE is fully open, the Hall sensor emits a signal by facing the magnet, and this signal is input to the control board.

[0087] The reduction gear 300 is a device that reduces the rotation of the output shaft 410 of the electric motor 400 and then transmits it to the screw shaft 210 of the ball screw 200.

[0088] The electric motor 400 is a rotating electric machine that generates the driving force necessary for the operation of the cutting blade CE, and is, for example, a brushless DC motor. The electric motor 400 has an output shaft 410. The output shaft 410 is a substantially cylindrical member, and its central axis coincides with the central axis of the screw shaft 210. A part of the output shaft 410 protrudes toward the reduction gear 300 and is connected to the reduction gear 300.

[0089] When current is supplied to the coil of the electric motor 400, the output shaft 410 rotates around its central axis. The rotation of the output shaft 410 is transmitted to the screw shaft 210 via the reduction gear 300, moving the nut 220 toward the front or rear end. This causes the cutting blade CE of the cutting mechanism 100 to open and close, as described above.

[0090] A rotation sensor is provided inside the electric motor 400. The rotation sensor is a sensor that emits a pulse signal each time the output shaft 410 rotates by a predetermined angle, and is mounted on a circuit board of the electric motor 400. The pulse signals from the rotation sensor are transmitted to a control board. The control board can determine the rotation angle of the output shaft 410 after a specific timing by counting the number of pulse signals. The control board can also determine the rotation speed of the output shaft 410 based on the number of pulse signals input per unit time. The rotation sensor may be a different type of sensor than that in this embodiment, as long as it can measure the rotation angle and rotation speed of the output shaft 410, and it may also be a sensor provided separately at a different location from the electric motor 400.

[0091] The control board is a circuit board provided to control the overall operation of the rebar cutting device 10, including the electric motor 400. The control board includes an inverter circuit for adjusting the current supplied to the electric motor 400, and a microcontroller for controlling switching operations in the inverter circuit, etc.

[0092] The battery 600 stores the power necessary for the operation of the electric motor 400 and the control board, and is, for example, a lithium-ion battery. The part of the rebar cutting device 10 that houses the battery 600 can be detached from the housing 11 as a battery pack and can be charged by connecting it to an external charger. Alternatively, the device may be configured to allow charging of the battery 600 while it remains attached to the housing 11.

[0093] Let's further explain the mechanism for operating the cutting blade CE. As mentioned earlier, in the rebar cutting device 10, the nut 220 and connecting member 230 of the ball screw 200 move linearly in a direction parallel to the central axis of the screw shaft 210 by the driving force of the electric motor 400. This movement of the connecting member 230 is converted into the opening and closing operation of the cutting blade CE provided on the cutting blade B via the link member 120. The nut 220, connecting member 230, link member 120, and cutting blade B constitute a "drive mechanism" that operates the cutting blade CE by the driving force of the electric motor 400. The nut 220 and connecting member 230, which are part of the drive mechanism, are "movable members" configured to move in the forward / backward direction X by the electric motor 400.

[0094] With the cutting blade B configured as described above, the crack that breaks is more likely to extend to connect the inner concave surface IC (or its surroundings) and the outer concave surface OC (or its surroundings). This makes it possible to suppress the frequency of cracks extending all the way to the rear end of the outer surface OS of the cutting blade B, and the frequency of short cracks reaching the first through-hole H1 from the inner surface IS adjacent to the first through-hole H1. It also makes it possible to suppress variations in how cracks enter.

[0095] The cutting blade B may also be provided with additional means to suppress the scattering of the broken cutting blade B. For example, the cutting blade B may include a pair of rubber members that clamp the cutting blade CE from the vertical direction Z, and a female screw portion formed therein that screws into a male screw 150 that penetrates the rubber members to fix the pair of rubber members. In addition, the cutting blade B or the rebar cutting device 10 may be provided with other means to solve problems such as the scattering of the broken cutting blade B.

[0096] [Modifications] Modifications of the cutting blade B of this embodiment will be described below. Figures 3A to 3C are perspective views of the cutting blade B1, cutting blade B2, and cutting blade B3 according to the first to third modifications. As shown in the figures, the outer concave surface OC is not limited to this embodiment and can be modified in various ways.

[0097] For example, as shown in Figure 3A, the outer surface OS of the cutting blade B1 may include an outer concave surface OC1 that is recessed in the direction approaching the inner surface IS and recessed in the thickness direction (vertical direction Z) from the first end face US, and an outer concave surface OC1 that is recessed in the direction approaching the inner surface IS and recessed in the thickness direction (vertical direction Z) from the second end face LS.

[0098] With this configuration, it becomes unnecessary to form grooves such as the outer concave surface OC on the outer surface OS of the cutting blade B1, making it possible to easily manufacture the cutting blade B1.

[0099] Furthermore, as shown in Figure 3B, the outer surface OS of the cutting blade B2 may include a plurality of outer concave surfaces OC2 that are recessed in the direction approaching the inner surface IS, spaced apart from each other in the thickness direction, and separated from the first end face US and the second end face LS.

[0100] With this configuration, it is possible to prevent the cutting blade B2 from tilting by installing guide members that enter each of the multiple outer concave surfaces OC2.

[0101] Furthermore, as shown in Figure 3C, the outer surface OS of the cutting blade B3 is recessed in the direction approaching the inner surface IS, and may also include an outer concave surface OC3 that is recessed in the thickness direction (vertical direction Z) from the first end face US or the second end face LS.

[0102] With this configuration, it becomes unnecessary to form grooves such as the outer concave surface OC on the outer surface OS of the cutting blade B1, making it possible to easily manufacture the cutting blade B1.

[0103] Similarly, the inner concave IC is not limited to this embodiment and can be modified in various ways. Figure 4 is a plan view of the cutting blade B1 according to the first modified example.

[0104] As shown in Figure 4, the inner surface IS of the cutting blade B1 may have an inner concave surface IC1 that is recessed in a direction approaching the outer surface OS in a region X1 forward of the position P2 of the center C1 of the first through hole H1 in the front-rear direction X, as well as a concave surface connected to this inner concave surface IC1 that is recessed in a direction approaching the outer surface OS in a region X2 backward of position P2.

[0105] Furthermore, this disclosure is subject to various modifications without departing from its essence. For example, within the ordinary creative ability of a person skilled in the art, some components of one embodiment may be added to other embodiments. Also, some components of one embodiment may be replaced with corresponding components of other embodiments.

[0106] Although various embodiments have been described above with reference to the drawings, it goes without saying that this disclosure is not limited to such examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of this disclosure. Furthermore, the components of the above embodiments may be combined in any way without departing from the spirit of the invention.

[0107] This application is based on a Japanese patent application (Patent Application No. 2024-213386) filed on December 6, 2024, the contents of which are incorporated by reference within this application.

[0108] According to this disclosure, it is possible to provide a cutting blade that can suppress the scattering of fractured fragments.

[0109] 10 Rebar cutting device 11 Housing 12 Trigger switch 100 Cutting mechanism 120 Link member 130 Guide member 140 Shaft member 150 Male screw 200 Ball screw 300 Reducer 400 Electric motor 410 Output shaft 600 Storage battery 700 Guide plate B, B1, B2, B3, BL, BU Cutting blade CE Cutting edge EP Extension part H1 First through hole H2 Second through hole IC Inner concave surface IS Inner surface LS Second end surface OC, OC1, OC2, OC3 Outer concave surface OS Outer surface PN1, PN2 Pin RP Cutting edge

Claims

1. A cutting blade to be attached to an electric rebar cutting device, the cutting blade having a blade portion extending in a first direction, an inner surface having a cut-off portion that connects to the rear end of the blade portion in the first direction and whose thickness increases in a thickness direction perpendicular to the first direction, and an outer surface connecting the front end and rear end of the inner surface, wherein a first hole located behind the blade portion and a second hole located behind the first hole are formed on the inner surface, wherein the region of the inner surface between the center of the first hole and the rear end of the blade portion in the first direction in the first direction includes an inner concave surface that is recessed in a direction approaching the outer surface, and the region of the outer surface between the center of the first hole and the rear end of the blade portion in the first direction in the first direction includes an outer concave surface that is recessed in a direction approaching the inner surface.

2. The cutting blade according to claim 1, wherein the region in the first direction where the inner concave surface is provided and the region in the first direction where the outer concave surface is provided overlap at least partially in the width direction perpendicular to the first direction and the thickness direction.

3. The cutting blade according to claim 1, wherein, in front of the region in the first direction where the first hole is formed, the region in the first direction where the inner concave surface is provided and the region in the first direction where the outer concave surface is provided overlap at least in part in the width direction perpendicular to the first direction and the thickness direction.

4. The cutting blade according to claim 1, wherein at least the blade portion, the cut-off portion, the inner concave surface, and the outer concave surface are formed symmetrically with respect to a virtual plane passing through the center of the cutting blade in the thickness direction.

5. The cutting blade according to claim 1, wherein the inner concave surface includes the inner surface of the cut-off portion.

6. The cutting blade according to claim 1, wherein a virtual cylindrical surface that is in contact with the inner surface and whose central axis is the central axis of the first hole intersects with the outer concave surface.

7. The cutting blade according to claim 6, wherein the virtual cylindrical surface is separated from the inner concave surface.

8. The cutting blade according to claim 1, wherein the width of the outer concave surface in the thickness direction is one-third or more of the thickness of the cutting blade.

9. The cutting blade according to claim 1, wherein the central axis of the second virtual cylindrical surface including the inner concave surface is spaced apart from the cutting blade.

10. The cutting blade according to claim 1, wherein the region of the outer surface, in the first direction, rearward from the center of the first hole, is recessed in a direction approaching the inner surface and includes a second outer concave surface that connects to the outer concave surface.

11. The cutting blade according to claim 1, wherein the cut-off portion is formed such that its entirety is included in the region between a position forward of the center of the first hole in the first direction and the rear end of the blade portion in the first direction.

12. A pair of cutting blades for cutting reinforcing bars by being attached to an electric reinforcing bar cutting device comprising an electric motor, a movable member configured to be movable in the front-rear direction by the electric motor, a pair of links connected to the movable member that open in a direction that increases the angle when the movable member moves forward and close in a direction that decreases the angle when the movable member moves backward, a pair of pins for providing a rotation axis, a shaft member positioned in front of the movable member, and a pair of guide members, wherein each cutting blade has a blade portion extending in a first direction, an inner surface having a cut-off portion that connects to the rear end of the blade portion in the first direction and whose thickness increases in a thickness direction perpendicular to the first direction, and an outer surface connecting the front end and rear end of the inner surface, and a first hole located behind the blade portion with respect to the first direction for inserting the pins, and a second hole located behind the first hole for connecting to the end of the links, A pair of cutting blades, wherein the region of the inner surface between the center of the first hole and the rear end of the blade in the first direction in the first direction is recessed in a direction approaching the outer surface and is formed to face the shaft member when the pair of cutting blades are close to each other, and the region of the outer surface between the center of the first hole and the rear end of the blade in the first direction in the first direction is recessed in a direction approaching the inner surface and is formed to allow the guide member to enter when the cutting blades move.

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