Firewood splitting tool

Abstract

To provide a firewood splitting tool which enables also people who are inexperienced in firewood splitting work to split firewood into appropriate sizes in a simple, safe and reliable manner without requiring large force.SOLUTION: A firewood splitting tool 1 comprises four blade bodies 20 extending radially from a center body part 10. Each blade body 20 comprises a flat bottom part 27, and a triangular cross-section blade edge 21 formed at an upper end and protruding upward. A tip 21a of the blade edge 21 has a spiral shape inclining downward while being curved toward the outside in a radial direction, and cross-section angles θ1 to θ3 of the blade edge 21 becomes larger toward the outside in the radial direction.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a firewood splitter for splitting firewood into appropriate sizes. [Background technology]

[0002] Traditionally, firewood used as fuel for bonfires and stoves has generally been split into pieces of appropriate size using an axe or similar blade (such as a hatchet) before use in order to dry out the inside (core) and make it easier to burn.

[0003] According to the Kojien dictionary, "firewood" is defined as "miscellaneous trees that have been cut, split into appropriate sizes, and dried," while "firewood splitting" is defined as "splitting firewood." Both the "wood" before and the "wood" after splitting are referred to as "firewood." However, for the sake of convenience, in the following, the wood before splitting will be referred to as "firewood" and the wood after splitting will be referred to as "thin wood."

[0004] By the way, in these days, which are being called the second camping boom, an increasing number of people are looking to enjoy a full-fledged outdoor lifestyle by making bonfires using thin firewood that they have split with their own hands, rather than using commercially available thin firewood.

[0005] However, splitting firewood into appropriate sizes using an axe or similar tool requires a certain level of skill, and because it involves swinging an axe or other blade, splitting firewood is a high and dangerous hurdle for those who are not accustomed to it. For this reason, it is possible to use a Kindling Cracker (registered trademark) and a hammer to split firewood easily and safely, but the Kindling Cracker (registered trademark) is relatively large and heavy, making it difficult to carry and unsuitable for casual camping, etc.

[0006] For example, Patent Document 1 discloses a relatively small and lightweight firewood splitter which consists of an upright long blade and two or more inclined blades which are connected to one end of the long blade and are arranged to be spaced apart at a predetermined angle, with a horizontal cutting edge of a predetermined length provided on the outside of the long blade and an inclined cutting edge which slopes down from the horizontal cutting edge towards the center, and which is arranged so that the cutting edges of the inclined blades slope down towards the center. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2004-305256 A Summary of the Invention [Problem to be solved by the invention]

[0008] In the above-mentioned Patent Document 1, when a hammer or similar tool is swung down on the top of a firewood placed on top of the firewood splitter, the tip of the blade cuts into the bottom of the firewood, creating a cut groove, and when the firewood is hit further with the hammer or similar tool, the cut groove is widened, splitting the firewood vertically into several thin pieces.

[0009] However, in the case of the knife in Patent Document 1, the vertical striking force applied to the firewood simply shears it in the vertical direction, so that a person with weak strength would need to strike even soft coniferous wood, for example, multiple times, which is inefficient and makes it difficult to split hard broadleaf wood with knots. Also, in the case of the knife in Patent Document 1, the vertical striking force simply cuts the tip of the blade into the bottom of the firewood, so the tip of the blade can bite (get pinched) into the bottom of the firewood, and in the worst case scenario, it can be difficult to split even soft coniferous wood.

[0010] The present invention has been made in consideration of the above points, and its object is to provide a firewood splitter that allows even a person who is unfamiliar with firewood splitting to split firewood into appropriate sizes easily, safely and reliably without requiring a lot of force. [Means for solving the problem]

[0011] In order to achieve the above-mentioned objective, the shape of the cutting edge of the firewood splitter of the present invention is formed in such a way that the force of striking the firewood is used to twist (rotate) it, widening the cracks in the firewood.

[0012] Specifically, the present invention is directed to a wood splitter that includes a plurality of blades that radiate from a central portion.

[0013] This firewood splitting tool is characterized in that each blade has a bottom having at least a flat portion, and a cutting edge formed at the upper end with a triangular cross-section that points upward, and the tip of the cutting edge forms a spiral shape that curves and slopes downward as it goes radially outward, and the cross-sectional angle of the cutting edge is configured to become larger as it goes radially outward.

[0014] With this configuration, the cross-sectional angle of the triangular cutting edge becomes larger as it moves radially outward (hereinafter simply referred to as "outside"); in other words, the angle becomes sharper as it approaches the center.Therefore, by striking the top of a piece of firewood placed vertically in the center with a hammer or the like, the cutting edges of the multiple blades can easily be driven into the base of the firewood.

[0015] In addition, because the tip of the blade is angled downward as it goes outward, and the cross-sectional angle of the blade increases as it goes outward, the blade can penetrate deeper into the bottom of the firewood while widening any cracks in the firewood caused by the blade biting into the center with the blade's increasing cross-sectional angle as the firewood is pushed down. This makes it possible to prevent the blade from biting into (getting pinched in) the bottom of the firewood.

[0016] Furthermore, because the tip of the blade curves outward and forms a downward spiral, as the firewood is pushed down by the striking force, the firewood is guided along the tip of the curved blade, and part of the vertical striking force is converted into a rotational force along the tip of the curved blade. As a result, when the firewood is driven into the wood, a force is generated that twists the firewood in the circumferential direction (around the center) where the multiple blades are lined up.

[0017] In this way, the cutting edge, whose cross-sectional angle gradually increases, pushes the cracks apart, and the firewood is twisted (a force that spreads the firewood in the circumferential direction), which combine to increase the breaking force and allow the firewood to be split reliably. Furthermore, since the crack surface of the firewood is roughly flat, while the cutting edge is curved, even when the cutting edge bites into the firewood, the two make point contact rather than surface contact, which prevents a sudden increase in resistance when the cutting edge bites into the firewood. Therefore, even people who are inexperienced in splitting firewood or who are weak in strength can split the firewood reliably without using a lot of force.

[0018] In addition, because each blade has a bottom with at least a flat portion, the firewood splitter can be easily set up on a firewood stand, stump, etc. Moreover, because the blade is provided on the firewood splitter, which is the side on which the firewood is set up, in other words, unlike an axe or the like, the blade is not swung around, which increases the safety of the firewood splitting operation.

[0019] As described above, the firewood splitter of the present invention enables even people who are inexperienced in firewood splitting or who have little strength to split firewood into appropriate sizes easily, safely and reliably.

[0020] In addition, the firewood splitter may be provided with an upwardly pointed protrusion in the central portion.

[0021] With this configuration, the firewood can be temporarily fixed in the center of the firewood splitter in a vertical position by simply inserting the pointed protrusions facing upward into the bottom of the firewood. By temporarily fixing the firewood in a vertical position in this way, the force of a blow from a hammer or other tool can be transmitted straight down, which prevents the firewood splitter from sliding sideways, unlike when the force of the blow is transmitted diagonally. This makes it easier, safer, and more reliable to split the firewood into appropriate sizes.

[0022] Furthermore, in the firewood splitting tool, the tip of the cutting edge may be rounded, and the radius of curvature R of the rounded edge may be set to gradually decrease radially inward.

[0023] With this configuration, the tip of the blade is rounded, which further increases safety. On the other hand, the radius of curvature R of the rounded cut is set to gradually decrease as it moves radially inward, i.e., toward the center, which makes it easier for the blade to bite into the bottom of the firewood. This makes it easier and more reliable to split firewood while still increasing safety.

[0024] In one embodiment, the firewood splitter may include four of the blades. Effect of the Invention

[0025] As described above, with the firewood splitter of the present invention, even a person who is unfamiliar with firewood splitting can easily, safely and reliably split firewood into appropriate sizes without requiring a great deal of force. [Brief description of the drawings]

[0026] [Figure 1] 1 is a perspective view showing a firewood splitter according to an embodiment of the present invention; FIG. [Diagram 2] FIG. 2 is a plan view showing a schematic diagram of a firewood splitting tool. [Diagram 3] FIG. 2 is an exploded perspective view showing a typical example of a firewood splitting tool. [Figure 4] FIG. 2 is a perspective view illustrating a typical manner in which the firewood splitter is used. [Diagram 5] 1A and 1B are diagrams for explaining the shape of a firewood splitter, in which FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line bb in FIG. [Figure 6] FIG. 2 is a diagram showing a schematic cross-sectional shape of a cutting edge, where FIG. 2(a) is a perspective view, and FIG. 2(b) to FIG. 2(d) are enlarged cross-sectional views of the tip of the cutting edge. [Figure 7] FIG. 2 is a perspective view showing a typical process of twisting a firewood. [Figure 8] This is a schematic diagram showing the steps of splitting firewood. [Figure 9] FIG. 2 is a perspective view showing a typical process of splitting firewood. [Figure 10] This is a diagram that illustrates the blade tip penetrating into firewood. [Figure 11] 1A and 1B are diagrams showing a schematic view of a firewood splitter according to a first modified embodiment of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line bb in FIG. [Figure 12] 13A and 13B are schematic diagrams showing a firewood splitter according to a second modified embodiment of the present invention, in which FIG. 13A is a plan view and FIG. 13B is a cross-sectional view taken along line bb in FIG. 13A. [Figure 13] FIG. 11 is a plan view showing a schematic diagram of a firewood splitter according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0028] (Embodiment 1) -Overall structure of firewood splitting tool- Fig. 1 is a perspective view, Fig. 2 is a plan view, and Fig. 3 is an exploded perspective view, each of which shows a firewood splitter 1 according to the present embodiment. As shown in Figs. 1 and 2, the firewood splitter 1 according to the present embodiment has a complex shape including many curved ridges, but in Fig. 3, the shape of the firewood splitter 1 is shown in a deformed manner to make it easier to understand the structure of the firewood splitter 1, and the firewood splitter 1, which is an integrally molded metal product, is shown in an exploded perspective view.

[0029] As shown in Figures 1 to 3, the firewood splitter 1 comprises a central main body 10, four blade bodies 20, and protrusions 30, and is a metal product in which the central main body 10, the four blade bodies 20, and the protrusions 30 are integrally formed.

[0030] The material of the firewood splitter 1 is not particularly limited as long as it is harder than wood, and may be, for example, metal, ceramic, or fiber-reinforced plastic. For example, in the case of metal, a relatively hard material may be special steel such as carbon tool steel (SK), or a relatively soft material may be general structural rolled steel (e.g. SS400). Since the firewood splitter 1 is repeatedly struck through the firewood 50 (see FIG. 4), from the viewpoint of durability, mechanical structural carbon steel (e.g. S45C or S50C) harder than general structural rolled steel may be used. In the case of a metal firewood splitter 1, it is preferable to perform a nitriding process in which nitrogen atoms are diffused and penetrated from the surface to the inside by heating to harden the surface, taking durability into consideration. On the other hand, in the case of fiber-reinforced plastic, glass fiber-reinforced plastic (glass fiber) in which glass fiber is added to plastic, carbon fiber-reinforced plastic in which carbon fiber is added to plastic, etc. may be used.

[0031] As shown in Fig. 3, the central body portion (central portion) 10 has curved side surfaces 11 that are curved inward (towards the center) as they go upward in a truncated quadrangular pyramid shape, and chamfered portions 13 that are C-chamfered corners between the curved side surfaces 11. By forming the chamfered portions 13 in this way, each curved side surface 11 has a triangular shape, and a square-shaped apex 15 is formed at the upper end of the central body portion 10, which is defined by the upper ends of the four chamfered portions 13. The bottom portion 17 of the central body portion 10 is formed flat.

[0032] The four blade bodies 20 extend radially outward from each of the four curved side surfaces 11 of the central body 10. The bottom 27 of each blade body 20 is formed flat, and the bottom 27 of each blade body 20 and the bottom 17 of the central body 10 are flush with each other (see FIG. 5(b)). As such, since the central body 10 and each blade body 20 have flat bottoms 17, 27, the firewood splitter 1 can be easily installed on a firewood splitting stand 70 (see FIG. 4), a stump, etc.

[0033] Each blade body 20 is formed so that the height decreases and the width decreases as it goes radially outward. Each blade body 20 has a flat bottom 27, but the height decreases as it goes radially outward, so as shown in FIG. 1, it is formed so that it narrows (tapers) as it goes radially outward when viewed horizontally. Also, each blade body 20 is formed so that the width decreases as it goes radially outward, so as shown in FIG. 2, it is formed so that it tapers as it goes radially outward when viewed from above. In this way, each blade body 20 is formed so that it narrows as it goes radially outward, and the four blade bodies 20 are not connected except at the central main body portion 10, in other words, the volume is made as small as possible, so it is possible to reduce the weight of the firewood splitter 1.

[0034] Moreover, each blade body 20 is curved clockwise as it moves radially outward when viewed from above. In this way, the four blade bodies 20 extending radially from the central main body 10 of the firewood splitter 1 are curved and narrow as they move radially outward, giving the firewood splitter 1 a shape resembling a swastika shuriken in plan view, as shown in Figure 2. The upper end of each blade body 20 forms a cutting edge 21, which will be described in detail later.

[0035] The protrusion 30 is formed in a quadrangular pyramid shape and is provided on the top 15 of the central main body 10 so as to be pointed upward. By providing the protrusion 30 pointed upward on the central main body 10 in this manner, it is possible to temporarily fix the firewood 50 in an upright position to the center (central main body 10) of the firewood splitter 1 by the simple task of piercing the protrusion 30 into the bottom 50b (see FIG. 4) of the firewood 50.

[0036] FIG. 4 is a perspective view that illustrates the use of the firewood splitter 1. When splitting firewood 50 using the firewood splitter 1 configured as above, first, as shown in FIG. 4, the protrusion 30 of the firewood splitter 1 placed on a firewood splitting stand 70 or the like is thrust into the bottom 50b of the firewood 50, and the firewood 50 is temporarily fixed to the firewood splitter 1 in a vertical position (extended vertically). Then, the top 50a of the firewood 50 temporarily fixed in a vertical position is struck with a hammer 60 or the like, and the firewood 50 is split into appropriate sizes using the four blades 20 on the side that are installed, without swinging a blade such as an axe. In this way, it is possible to make a fire using thin pieces of firewood 50 split by hand, rather than using commercially available thin pieces of firewood.

[0037] -Cutting edge configuration- FIG. 5 is a diagram for explaining the shape of the wood splitter 1, where FIG. 5(a) is a plan view and FIG. 5(b) is a cross-sectional view taken along line bb in FIG. 5(a). FIG. 6 is a diagram for showing the cross-sectional shape of the cutting edge 21, where FIG. 5(a) is a perspective view and FIG. 5(b)-(d) are enlarged cross-sectional views of the tip of the cutting edge 21. The perspective cross-sectional view indicated by hatching B in FIG. 6(a) and FIG. 6(b) are parts of the cross-sectional view taken along line VIb-VIb in FIG. 5(a), the perspective cross-sectional view indicated by hatching C in FIG. 6(a) and FIG. 6(c) are parts of the cross-sectional view taken along line VIc-VIc in FIG. 5(a), and the perspective cross-sectional view indicated by hatching D in FIG. 6(a) and FIG. 6(d) are parts of the cross-sectional view taken along line VId-VId in FIG. 5(a). Although FIGS. 6(b) to (d) are cross-sectional views, hatching has been omitted to make the drawings easier to see.

[0038] As described above, the upper end of each blade body 20 constitutes the cutting edge 21. More specifically, as shown by hatching B, hatching C, and hatching D in Fig. 6(a), the cutting edge 21 is formed at the upper end of each blade body 20 and has a triangular cross section that points upward when viewed in the radial direction (the direction in which the blade body 20 extends).

[0039] As shown in Fig. 5(b), the tip 21a of the cutting edge 21 is inclined downward as it moves radially outward. Also, as shown in Fig. 5(a), the tip 21a of the cutting edge 21 is curved clockwise in a plan view so that the distances L1, L2, L3, and L4 from the reference line RL become greater as it moves radially outward, such that L4>L3>L2>L1. In other words, the tip 21a of the cutting edge 21 forms a spiral shape that curves and slopes downward as it moves radially outward.

[0040] Fig. 7 is a perspective view showing a typical state in which a twist is applied to firewood 50. When a hammer 60 or the like strikes top 50a of firewood 50, which is temporarily fixed in an upright position, firewood 50 is pushed down as shown by the white arrow in Fig. 7, and at that time, because tip 21a forms cutting edge 21 so as to be spiral, a twist is applied to firewood 50 as shown by the thick arrow in Fig. 7.

[0041] More specifically, the tip 21a of the cutting edge 21 forms a spiral shape that curves and slopes downward as it goes radially outward, so that as the firewood 50 is pushed down by the striking force, the firewood 50 is guided along the curved tip 21a of the cutting edge 21, and part of the vertical striking force is converted into a rotational force along the curved tip 21a of the cutting edge 21. As a result, when the firewood 50 is driven in, a force is generated that twists the firewood 50 in the circumferential direction (around the central body portion 10) where the four blade bodies 20 are lined up.

[0042] Moreover, the cross-sectional angle θ of the cutting edge 21 having a triangular cross section is configured to increase radially outward. Specifically, as shown in Figures 6(b), 6(c), and 6(d), the cross-sectional angle θ of the cutting edge 21 is configured such that the cross-sectional angle θ2 corresponding to the hatching C radially outward from the hatching B is greater than the cross-sectional angle θ1 corresponding to the hatching B, and the cross-sectional angle θ3 corresponding to the hatching D radially outward from the hatching C is greater than the cross-sectional angle θ2 corresponding to the hatching C.

[0043] Figure 8 is a schematic diagram showing the stages of splitting firewood 50. With the above configuration, the cross-sectional angle θ of the triangular cutting edge 21 becomes acute as it approaches the center of the firewood splitter 1, so that by applying a blow with the hammer 60 to push down the firewood 50 as shown by the white arrow in Figure 8(a), the cutting edges 21 of the four blades 20 can be easily inserted into the bottom 50b of the firewood 50 as shown in Figure 8(b).

[0044] In addition, since the tip 21a of the cutting edge 21 slopes downward as it moves radially outward and the cross-sectional angle θ of the cutting edge 21 increases as it moves radially outward, as shown in Figure 8(b), cracks in the firewood 50 caused by the cutting edge 21 digging into the center near the center are widened by the cutting edge 21, whose cross-sectional angle θ increases, as shown by the blackened area in Figure 8(d) as the firewood 50 is pushed down, as shown in Figure 8(c), allowing the cutting edge 21 to dig deeper into the bottom 50b of the firewood 50.

[0045] Similarly, as shown in Fig. 8(d), as the firewood 50 is pushed further down, the cutting edge 21 can penetrate even deeper into the bottom 50b of the firewood 50 while further spreading the cracks in the firewood 50 that have been spread apart as shown in Fig. 8(e) by the cutting edge 21 whose cross-sectional angle θ becomes even larger as shown by the blackened area in Fig. 8(f). This makes it possible to prevent the cutting edge 21 from biting (getting pinched) into the bottom 50b of the firewood 50.

[0046] In this way, the crack is pushed open by the cutting edge 21, whose cross-sectional angle θ gradually increases radially outward, and a twist is applied to the firewood 50 (a force that tries to spread the firewood 50 in the circumferential direction) as shown by the thick arrows in Figures 8(b), 8(d) and 8(f), which combines to increase the breaking force, thereby enabling the firewood 50 to be split reliably, as shown in Figure 9.

[0047] FIG. 10 is a diagram for explaining the state of the cutting edge 21 biting into the firewood 50. As described above, in the firewood splitter 1 according to this embodiment, the cutting edge 21 can be caused to bite deeper into the bottom 50b of the firewood 50, so it is thought that a sudden increase in resistance occurs when the cutting edge 21 bites into the firewood. However, as shown in FIG. 10, the split surface 51 of the firewood 50 is approximately flat, while the cutting edge 21 is curved, so even if the cutting edge 21 bites into the firewood 50, the two 51, 21 are in point contact rather than surface contact, so a sudden increase in resistance when the cutting edge 21 bites into the firewood can be suppressed. Therefore, by using the firewood splitter 1, the firewood 50 can be split reliably without requiring a large force.

[0048] Moreover, in the firewood splitter 1 of this embodiment, the projection 30 is thrust into the bottom 50b of the firewood 50 to temporarily fix the firewood 50 in an upright position, so the force of the impact of the hammer 60 can be transmitted straight down, which, unlike cases where the force of the impact is transmitted diagonally, prevents the firewood splitter 1 from sliding sideways. This makes it even easier, safer and more reliable to split the firewood 50 into appropriate sizes.

[0049] Furthermore, in the wood splitter 1 of this embodiment, the tip 21a of the cutting edge 21 is rounded, and the radius of curvature R of the rounded edge is set to gradually decrease radially inward. Specifically, as shown in Figures 6(b), 6(c), and 6(d), the radius of curvature R of the rounded edge of the tip 21a of the cutting edge 21 is set so that the radius of curvature R2 corresponding to the hatching C, which is radially inward from the hatching D, is smaller than the radius of curvature R3 corresponding to the hatching D, and the radius of curvature R1 corresponding to the hatching B, which is radially inward from the hatching C, is smaller than the radius of curvature R2 corresponding to the hatching C.

[0050] As described above, in this embodiment, the blade body 20 is provided on the firewood splitter 1, which is the side to be installed. In other words, unlike an axe, the blade is not swung around, which increases the safety of the firewood splitting operation. In addition, the tip 21a of the cutting edge 21 is rounded, which further increases safety. On the other hand, the curvature radius R of the rounded edge is set to gradually decrease as it moves radially inward, i.e., toward the center, which makes it easier for the cutting edge 21 to bite into the bottom 50b of the firewood 50. As a result, it is possible to easily and reliably split the firewood 50 while further increasing safety.

[0051] As described above, with the firewood splitter 1 according to this embodiment, even people who are inexperienced in firewood splitting or who have little strength can easily, safely and reliably split the firewood 50 into appropriate sizes.

[0052] (Variation 1) This modified example differs from the above embodiment in that a lightening hole is provided in the firewood splitter 1. The differences from the embodiment will be described below.

[0053] Fig. 11 is a schematic diagram of a firewood splitter 1 according to this modified example, with Fig. 11(a) being a plan view and Fig. 11(b) being a cross-sectional view taken along line bb in Fig. 11(a). As shown in Fig. 11, in this firewood splitter 1, a recessed hole 19 is formed in the bottom 17 of the central body 10, and a recessed hole 29 is formed in the bottom 27 of each blade 20, which allows the firewood splitter 1 to be made lighter.

[0054] (Variation 2) This modified example differs from the above embodiment in that spikes are provided on the bottom 27 of the firewood splitter 1. The differences from the embodiment will be described below.

[0055] Fig. 12 is a schematic diagram of a firewood splitter 1 according to this modified example, where Fig. 12(a) is a plan view and Fig. 12(b) is a cross-sectional view taken along line bb in Fig. 12(a). As shown in Fig. 12, this firewood splitter 1 has a plurality of spikes (protrusions) 80 protruding downward formed on the bottom 27 of each blade 20. This allows the spikes 80 to dig into the stump when the firewood splitter 1 is placed on a stump or the like, thereby more reliably preventing the firewood splitter 1 from sliding sideways.

[0056] (Other embodiments) The present invention is not limited to the embodiments, and can be embodied in various other forms without departing from the spirit or main characteristics thereof.

[0057] In the above embodiment, four blade bodies 20 are provided, but the number is not limited to this, and for example, three blade bodies 20 or five or more blade bodies 20 may be provided.

[0058] In addition, in the above embodiment, the bottom 27 of the blade body 20 is formed flat, but this is not limited to the above, and as long as the bottom 27 has at least a flat portion, a groove (not shown) for preventing slipping may be formed in the bottom 27.

[0059] Furthermore, in the above embodiment, the blade body 20 is formed so that it narrows (tapers) as it goes radially outward whether viewed horizontally or from above, but this is not limiting, and the firewood splitter 1' may be formed so that the blade body 20' does not taper when viewed from above, for example, as shown in Figure 13. Even in this case, the tip 21a' of the cutting edge 21' forms a spiral shape that curves and slopes downward as it goes radially outward, so the blade body 20' tapers when viewed horizontally.

[0060] As such, the above-described embodiment is merely illustrative in all respects and should not be interpreted as being limiting. Furthermore, all modifications and variations within the scope of the claims are within the scope of the present invention. [Industrial Applicability]

[0061] According to the present invention, even a person who is not accustomed to splitting firewood can easily, safely and reliably split firewood into appropriate sizes without using a lot of force, so it is extremely useful when applied to a firewood splitter that splits firewood by hitting it with a hammer or the like. [Explanation of symbols]

[0062] 1, 1' wood splitter 10 Central body part (central part) 20, 20' blade 21, 21' cutting edge 21a, 21a' tip 27 Bottom 30 Protrusion R1, R2, R3 radius of curvature θ1, θ2, θ3 Section angle

Claims

1. A firewood splitter having a plurality of blades extending radially from a central portion, Each of the blades has a bottom portion having at least a flat portion, and a cutting edge formed at an upper end portion and having a triangular cross section that points upward, This firewood splitting tool is characterized in that the tip of the cutting edge is spirally curved and inclined downward as it moves radially outward, and the cross-sectional angle of the cutting edge is configured to become larger as it moves radially outward.

2. The firewood splitter according to claim 1, A firewood splitter characterized in that the central portion is provided with a pointed protrusion pointing upward.

3. The firewood splitter according to claim 1, The tip of the blade is rounded, This firewood splitter is characterized in that the radius of curvature R of the R processing is set to gradually become smaller as it goes radially inward.

4. The firewood splitter according to claim 1, A firewood splitter comprising four of the above blades.

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