carving knife

Abstract

To allow only one graver to perform many of fine works on a material.SOLUTION: A graver 100 includes a handle and a blade body 120. The blade body 120 is metallic and rod-like, and a leading end thereof has a triangular pyramid-like triangular pyramid part 122. Three sides of side faces of the triangular pyramid part 122, which are a side 122X, a side 122Y, and a side 122Z, function as blades. By using two of these three sides, the triangular pyramid part 122 is moved in a reciprocating manner against an object using the graver, thereby press graving and pull graving can be performed on the object alternatively.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a chisel suitable for performing fine work. [Background technology]

[0002] There are cases where it is necessary to use a carving knife to perform intricate work. Of course, there are also cases where intricate work is required for other purposes, but for example, when making netsuke, which were used as fasteners for tobacco pouches, inro (seal cases), and purses during the Edo period and which have become works of art for many collectors today, intricate work using a carving knife is essential. Netsuke making is not limited to professional netsuke craftsmen. There are also many people who make netsuke as a hobby. Therefore, there is a fair amount of demand for intricate work using carving knives.

[0003] Netsuke are small, with each piece fitting into a rectangular prism measuring between 1cm and 6-7cm, depending on the motif. Furthermore, many of them have extremely complex three-dimensional shapes. Therefore, the process of creating a netsuke, which relies on the manual labor of carving the material with a carving knife, is fraught with difficulties due to the size of the hand and carving knife, as well as the limitations on the direction in which the hand can be moved with sufficient force. Depending on the design of the netsuke, it may be necessary to work inside the holes drilled in the netsuke material or the holes that pass through the material, and in such cases the above difficulties become even greater.

[0004] To alleviate some of these difficulties, netsuke craftsmen have traditionally developed a wide variety of chisels with different blades to suit the required intricacy. For example, a flat knife, a round knife, a triangular knife, etc. are carving knives with the blade located on the right side when in use, and can be used for push cutting. On the other hand, there are various types of chisels called left-hand blades, which have a blade on the left side when in use. Left-hand blades generally have a blunt cutting edge and are suitable for press cutting. There is also a chisel called a clamshell chisel, which has a rod-shaped blade with a cross section shaped like a clam shell and multiple continuous blades that run the entire length of the blade. Like a file, a clamshell chisel is used by moving the blade back and forth along its length against the material, and is useful for cutting grooves or drilling holes in the material for netsuke. Summary of the Invention [Problem to be solved by the invention]

[0005] Although there are many different types of carving knives, it is still difficult to carve the netsuke material in such a fine way. According to the inventor's observations, the reason for this difficulty is that conventional carving knives, with the exception of the clamshell gangi, can only be used to work on the material when pushing. If the carving knives could be used to cut and carve the material when pulling as well as when pushing, the degree of freedom in work would increase, but conventional carving knives basically only allow the carving knives to work on the material when used in a pushing motion, making it difficult to work on the material of a netsuke. Netsuke are made from a variety of materials. The most common is wood, but there are also hard woods such as boxwood and ebony. Ivory and horns (ivory, boar tusk, birch tooth, deer antler, etc.) are also used as netsuke materials, but these are also often hard. When the netsuke material is hard, the blade of the carving knife easily slips against the material, making it extremely difficult to carve intricate details. Furthermore, natural materials such as wood, tusks, and horns have anisotropy called grain. For example, if you move a chisel along the grain, you can cut or shave the material, but if you move the chisel against the grain, the blade of the chisel will get caught on the material and you will hardly be able to cut or shave the material. Therefore, since ancient times, netsuke craftsmen have been forced to use various types of chisels when making intricate cuts on the material in order to create netsuke, and to devise ways to press the chisel along the grain of the material, even changing the grip of both the material and the chisel to achieve the desired positional relationship.

[0006] Such ingenuity poses great difficulties for the netsuke artist, but for those who make netsuke as a hobby, it can be said that it is almost impossible to overcome. This is because hobbyists who make netsuke generally do not own many carving knives, and the range of choices is limited. Therefore, even if one selects an appropriate knife from several types, and even if one tries to devise ways to press the knives along the grain of the material by adjusting one's grip on both the material and the carving knives to achieve the desired positional relationship, the range of possible ingenuity is inevitably limited. Considering these points, there is nothing better for netsuke artisans and those who make netsuke as a hobby than being able to perform a variety of carvings with just one carving knife.

[0007] An object of the present invention is to provide a technique that enables fine work on a material using a carving knife to be performed to at least a certain extent using a single carving knife. [Means for solving the problem]

[0008] The present invention is as follows. The present invention is a chisel comprising a rod-shaped handle sized and shaped to be held in one hand, and a rod-shaped metal blade body with a blade at a portion thereof, the base end of which is fixed to the handle. The chisel also comprises a triangular pyramid portion at the tip of the blade body, the tip of which is an apex, and each of the three sides extending from the apex of the triangular pyramid portion forms a triangular pyramid blade. The basic structure of such a chisel is a rod-shaped handle and a rod-shaped blade. This basic structure is the same as that of a conventional chisel. The handle is for the user to hold and is made of wood, for example. The blade has a cutting edge and is made of metal. The key feature of the carving knife of the present invention is that it has a triangular pyramid portion at the tip of the blade body. The triangular pyramid portion is a part of the blade body, and is a triangular pyramid-shaped portion that exists at the tip of the blade body. The triangular pyramid portion has a triangular pyramid shape with the tip of the blade body as its apex. Here, "apex" means a apex that is not included in the base of the triangular pyramid. In this application, when referring to the "apex" of a triangular pyramid portion, "apex" has the same meaning. The triangular pyramid portion has three sides extending from its apex. Each of the three sides is in contact with two triangular flat surfaces. The three sides between the two flat surfaces form the blade. In other words, near the tip of this carving chisel, there are three blades that intersect at the apex of the triangular pyramid portion. Therefore, a user of this carving chisel can bring any two of the three blades close to the object to be carved with the chisel, such as the material for a netsuke, and perform a wiper motion at a predetermined angle using a predetermined point near the tip of the blade as a fulcrum. This allows the user to act on the object both when pushing and pulling, thereby carving the surface of the object. This makes it easier to carve with a carving knife, even if the object is hard or has a grain. Being able to carve an object both when pushing and pulling means that, even taking the grain into account, the object can be carved with at least one of these movements, so using the carving knife of the present invention reduces the chance of encountering a situation where the object cannot be carved. This means that the carving knife of the present invention eliminates the need to prepare various types of carving knives.

[0009] As described above, the tip of the blade body of the carving knife of the present invention has three triangular pyramidal blades that function as cutting edges. The cutting angles of the three triangular pyramidal blades do not need to be sharp. For example, the cutting angles of the three triangular pyramidal blades can be any suitable angle between 20° and 80°. The three angles of the triangle that forms the base of the triangular pyramid can also be similar. If the three angles of the triangle that forms the base of the triangular pyramid perpendicular to the longitudinal direction of the blade body are as described above, and the apex of the triangular pyramid is positioned at a specific point on the base of the triangular pyramid (e.g., near the center of gravity of the base) at a specific point on a line perpendicular to the base, as long as the distance from the apex of the triangular pyramid to the base is within an appropriate range, the cutting angles of the three triangular pyramidal blades will be slightly larger than each of the three angles of the base of the triangular pyramid. Two of the three triangular pyramidal blades may have the same cutting angle, and the other may have a smaller cutting angle. By making the cutting angles of the two triangular pyramidal blades the same, the user can perform push-cutting and pull-cutting by moving the carving knife back and forth using the two triangular pyramidal blades with the same cutting angle, allowing the user to perform push-cutting and pull-cutting in a reciprocating motion with the same feel. Furthermore, by making the cutting angle of one of the three triangular pyramidal blades different from the cutting angles of the two triangular pyramidal blades with the same cutting angle, two variations in the angle of the triangular pyramidal blade can be achieved, thereby enabling two variations in push-cutting using the triangular pyramidal blade. Because the cutting angles of the blades required for press-cutting and pull-cutting are not as sharp as those of the left-hand chisel, it is reasonable to set the cutting angles of the two triangular pyramidal blades used when reciprocating the chisel to perform press-cutting and pull-cutting larger than those of the other triangular pyramidal blades. Furthermore, making the cutting angle of one triangular pyramidal blade smaller than that of the other triangular pyramidal blades with the same cutting angle allows the triangular pyramidal blade with a smaller cutting angle to perform not only press-cutting but also push-cutting, which is also advantageous for increasing the variety of processing that can be performed on an object using the triangular pyramidal blades. The cutting angles of the two triangular pyramidal blades with the same cutting angle can be, for example, approximately 61° to 80°. The cutting angle of the other triangular pyramidal blade can be, for example, approximately 20° to 58°. For example, the base of the triangular pyramidal portion can be an isosceles triangle. In this case, the angle at the apex of the base sandwiched between each of the two sides of the isosceles triangle and the other side of the triangular pyramid, which has the same length, can be approximately 61° to 80°.

[0010] As described above, the blade is rod-shaped. At least one-third of the tip of the blade may be curved along an arc. As already mentioned, the triangular pyramidal portion at the tip of the blade body of the carving knife of the present invention has three triangular pyramidal blades, allowing the carving knife of the present invention to perform various fine work on an object. In such a carving knife, at least one-third of the tip of the blade body can be curved in an arc. This makes it easier to adjust the angle when the blade body, and therefore the triangular pyramidal blade, is applied to an object, making it easier to apply the triangular pyramidal blade to difficult-to-cut areas of the object. In other words, by providing a curved portion at the tip of the blade body, the carving knife can perform even more detailed work on an object. An example of a difficult-to-cut area is the inside of a hole or aperture drilled in the object. Even when the blade body has a curved portion, two of the three triangular pyramidal blades in the triangular pyramidal portion can have the same cutting angle, and the remaining triangular pyramidal blade can have a smaller cutting angle. In this case, the two triangular pyramidal blades with the same cutting angle can be located inside the curved portion and symmetrically positioned with respect to a plane including the center line (axis of the blade body) of the blade body in the curved portion. This allows the two triangular pyramidal blades with the same cutting angle to be located symmetrically on the inside of the curved portion (inside the curve formed by the blade body), allowing a user holding the handle to intuitively grasp the positions of the two triangular pyramidal blades with the same cutting angle (the angle at which the triangular pyramidal blades exist around the axis of the blade body) and the position of the remaining triangular pyramidal blade.

[0011] The blade body may be configured so that its thickness gradually increases from the tip side to the base end in a predetermined range from the base end of the triangular pyramid portion toward the base end, and may be provided with a ganged blade consisting of multiple consecutive blades with blade angles of 30° to 75° on one surface of the blade body as viewed from the front in the predetermined range in which the thickness gradually increases from the tip side to the base end. By including such a gong blade, this carving knife can be used in the same way as a clam gong blade, that is, by moving the blade back and forth along the length of the blade, to cut grooves or drill holes or apertures in an object. This allows the carving knife of the present invention to perform different types of fine work on an object than when using a triangular pyramidal blade. Furthermore, because the gong blade is located in a range of the blade body where the thickness of the blade gradually increases from the tip to the base, it is possible to change the thickness of the groove cut into the object by selecting which range of the gong blade along the length of the blade body to use. The blades each having a blade angle of 30° to 75° may be substantially V-shaped when viewed from the front of the blade body, making the blade suitable for cutting grooves in an object. A crossbeam blade can also be provided on a blade body that has a curved portion. For example, the blade body may be configured such that the thickness gradually increases from the distal end to the proximal end within a predetermined range extending from the base end of the triangular pyramid portion to the proximal end. A crossbeam blade consisting of multiple successive blades with cutting angles of 30° to 75° may be provided on one surface of the blade body as viewed from the front within the predetermined range, and the crossbeam blade may be located outside the curved portion. By providing a crossbeam blade on the outside of the blade body, it becomes easier to press the blade body against an object with force when moving the portion of the blade body where the crossbeam blade is located back and forth relative to the object, making it easier to cut grooves in the object using the crossbeam blade of the carving knife of the present invention. The range in which the blade body's thickness changes may, but need not, coincide with the range of the curved portion of the blade body. The multiple blades included in the gong blade, each with a blade angle of 30° to 75°, may be substantially V-shaped when viewed from the front of the blade body, and the apex of each V-shaped blade with a blade angle of 30° to 75° may be positioned so that it lies on a plane including the center line of the blade body at the curved portion. This allows the apexes of the V-shaped blades included in the gong blade to be aligned with the outer edge of the arc-shaped blade body at the curved portion. This not only makes it easier to apply force to press the blade body against the object when moving the portion of the blade body where the gong blade is located back and forth relative to the object, but also enables the aligned apexes of the multiple V-shaped blades included in the gong blade to be moved linearly back and forth relative to the object. This further facilitates cutting grooves into an object using the gong blade of the carving knife of the present invention. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an overall perspective view of a carving knife according to an embodiment; [Figure 2] FIG. 2 is an enlarged perspective view of the blade of the carving knife shown in FIG. 1. [Figure 3]2A is a right side view, FIG. 2B is a plan view, FIG. 2C is a left side view, and FIG. 2D is a bottom view of the cutting edge of the carving knife shown in FIG. 1. [Figure 4] FIG. 2 is a front view of the triangular pyramidal portion of the carving knife shown in FIG. [Figure 5] FIG. 2 is a front view showing three overlapping cross sections of the blade of the carving knife shown in FIG. 1, where the ganged blade is located. [Figure 6] 2 is a perspective view showing the state in which a user holds the carving knife shown in FIG. 1. [Figure 7] 2 is a perspective view showing one mode of working an object using the carving knife shown in FIG. 1. FIG. [Figure 8] 1. FIG. 4 is a perspective view showing another example of the method for carving an object using the carving knife shown in FIG. [Figure 9] 1. FIG. 4 is a perspective view showing still another mode in which an object is worked using the carving knife shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] A preferred embodiment of the present invention will now be described in detail with reference to the drawings.

[0014] FIG. 1 shows a perspective view of an entire chisel 100 according to one embodiment. The carving knife 100 includes a handle 110 and a blade 120 as is known or commonly known. The handle 110 is for the user to grip, and may employ any known or well-known configuration for a carving knife. The handle 110 is sized and shaped to be held in one hand and is rod-shaped overall. In this embodiment, the handle 110 is generally cylindrical, although not limited thereto. However, its cross-sectional shape is slightly flattened in the vertical direction (the concept of the orientation of the carving knife 100, including the vertical direction, will be explained later), making it nearly elliptical. By flattening the cross-section of the handle 110, a user holding the handle 110 can intuitively recognize the up and down of the carving knife 100. Although not limited thereto, the tip of the handle 110 is slightly tapered, and the rear end of the handle 110 is rounded. The material of the handle 110 can be appropriately selected from known or well-known materials. In this embodiment, the material of the handle 110 is wood. However, the material of the handle 110 can also be resin or metal.

[0015] The blade body 120 is provided with a blade for performing cutting on an object to be cut. The "blade" provided on the blade body 120 in this embodiment refers to a triangular pyramidal blade and a blade included in a Ganki blade, both of which will be described later. The blade body 120 is made of metal and is rod-shaped. The base end of the blade body 120 is fixed to the tip of the handle 110. The blade body 120 can be fixed to the handle 110 using known or well-known techniques, and this is done in this embodiment. For example, the base end of the blade body 120 is fixed to the tip of the handle 110 in a state where it is embedded in the tip of the handle 110 by a predetermined length. At least one-third of the tip end of the rod-shaped blade body 120, and although not limited thereto, approximately one-half of the tip end in this embodiment, is curved in an arc-like shape as a curved portion 121 (see FIGS. 1, 2, and 3). The curved portion 121 may extend over the entire length of the blade body 120. In this embodiment, the blade body 120 at the curved portion 121 is curved upward, although this is not necessarily the case. For convenience, in this embodiment, the upper side in FIG. 3(A) is defined as the upper side of the carving knife 100, and the lower side in FIG. 3(A) is defined as the lower side of the carving knife 100. The left side of FIG. 3(A) is defined as the tip or front of the carving knife 100 or blade body 120. According to this definition, FIG. 3(A) is a right side view of the blade body 120, FIG. 3(B) is a plan view of the blade body, FIG. 3(C) is a left side view of the blade body 120, and FIG. 3(D) is a bottom view of the blade body 120. The curvature of the curved portion 121 of the blade body 120 can be appropriately determined within a range that allows easy application of force when using the carving knife 100 to carve an object.

[0016] The tip of the blade body 120 is provided with a triangular pyramid portion 122. The triangular pyramid portion 122 is a part of the blade body 120. The triangular pyramid portion 122 has a triangular pyramid shape with vertices 122A, 122B, and 122C as the base and vertex 122D as the vertex not included in the base. Vertex 122D is located at the tip of the blade body 120. Although not limited to this, the base of the triangular pyramid portion 122 in this embodiment is perpendicular or nearly perpendicular to the longitudinal direction of the blade body 120. 4, the bottom surface of triangular pyramid portion 122 is an isosceles triangle in which the length of the side connecting vertices 122A and 122B is equal to the length of the side connecting vertices 122A and 122C. In this embodiment, the size of the interior angle at vertex 122B on the bottom surface and the size of the interior angle at vertex 122C are both α°, and the size of the interior angle at vertex 122A is β°. When viewed from the front, the bottom surface of triangular pyramidal portion 122 is positioned symmetrically with respect to the axis of blade body 120. Of the bottom surface of triangular pyramidal portion 122, vertices 122B and 122C, which have an interior angle of α°, are both located inside the curve of curved portion 121. Furthermore, apex 122D of triangular pyramid portion 122 is located slightly above the upper end of the base of the shaft of blade body 120 relative to handle 110. In Fig. 3(A), apex 122D is located above the dashed line extending from the upper end of handle 110 of the shaft of blade body 120 to the left (toward the tip of carving knife 100, parallel to the axis of rod-shaped handle 110).

[0017] The three sides connecting the vertex 122D of the triangular pyramid portion 122 with the vertex 122A, the vertex 122B, and the vertex 122C function as blades. As shown in FIG. 4 , side 122X, which is the side connecting vertex 122D and vertex 122B, is the side where the triangular plane formed by vertices 122A, 122B, and 122D meets the triangular plane formed by vertices 122B, 122C, and 122D, and both planes form a blade. Side 122X is one of the triangular pyramidal blades referred to in the present invention. Side 122Y, which is the side connecting vertices 122D and 122C, is the side where the triangular plane formed by vertices 122A, 122C, and 122D meets the triangular plane formed by vertices 122B, 122C, and 122D, and both planes form a blade. Side 122Y is one of the triangular pyramidal blades referred to in the present invention. Side 122Z, which is the side connecting vertex 122D and vertex 122A, is the side where the triangular plane formed by vertices 122A, 122B, and 122D meets the triangular plane formed by vertices 122A, 122C, and 122D, and the blade is formed by both planes. Side 122Z is ​​also one of the triangular pyramidal blades defined in the present invention. The triangular pyramidal blades on sides 122X and 122Y are both positioned inside the curve of curved portion 121, and when viewed from the front, these two triangular pyramidal blades are symmetrical with respect to the axis of blade body 120. Although not limited to this, vertex 122D when viewed from the front is located near the center of gravity of the bottom of triangular pyramidal portion 122. In this embodiment, although not limited to this, vertex 122D when viewed from the front is located on the perpendicular bisector of the side between vertices 122B and 122C on the bottom of triangular pyramidal portion 122, slightly closer to the center of gravity of the bottom than the side between vertices 122B and 122C. Therefore, unless the distance from vertex 122D to the bottom of triangular pyramidal portion 122 is significantly closer than that shown in FIG. 2, the cutting angle of the triangular pyramidal blade at sides 122X and 122Y will be slightly smaller than α°, and the cutting angle of the triangular pyramidal blade at side 122Z will be slightly smaller than β°. Although not necessarily limited to this, in this embodiment, the cutting angles of the triangular pyramidal blades at sides 122X and 122Y are the same, and the cutting angle falls within a range of, for example, 61° to 80°. Also, although not necessarily limited to this, in this embodiment, the cutting angle of the triangular pyramidal blade at side 122Z is ​​smaller than the cutting angle of the triangular pyramidal blade at sides 122X and 122Y, and the cutting angle falls within a range of, for example, 20° to 58°. In any case, the cutting angles of the three triangular pyramidal blades at sides 122X, 122Y, and 122Z are all within a range of 20° to 80°.

[0018] The blade body 120 is configured so that its thickness gradually increases from the distal end toward the proximal end within a predetermined range extending from the proximal end of the triangular pyramidal portion 122 toward the proximal end of the blade body 120. This range in which the thickness of the blade body 120 changes may or may not coincide with the range of the curved portion 121. Although not limited to this, the blade body 120 in this embodiment is configured so that its thickness gradually increases toward the proximal end of the blade body 120 over the entire length from the proximal end of the triangular pyramidal portion 122 to the proximal end of the blade body 120. Of the aforementioned range in which the thickness of the blade body 120 varies, in this embodiment, the gong blade 123 is provided in the range corresponding to the curved portion 121. The gong blade 123 is provided with a plurality of continuous gong blade bodies 123A. The gong blade bodies 123A are arranged in a row on one surface of the blade body 120 when viewed from the front. Although not limited to this, in this embodiment, the gong blade bodies 123A are arranged in a row along the underside of the blade body 120. In other words, the gong blade 123 or the gong blade bodies 123 in this embodiment are positioned outside the curve of the curved portion 121. Figure 5 shows a view of the front of the blade 120 at the location of three of the many ganged blade bodies 123A lined up from the tip of the blade 120. Figure 5 shows a superposition of cross-sectional views of the blade 120 at the locations of the three ganged blade bodies 123A. At the locations where the ganged blade bodies 123A are located, the cross section of the blade 120 is shaped like an inverted teardrop, or like a clamshell when viewed from the side. This teardrop or clamshell shape is the common cross-sectional shape of the blade 120 at all locations where the ganged blade bodies 123A are located. The size of the cross-section decreases as it approaches the tip of the blade 120. Roughly speaking, the crossbeam blade 123A is formed by providing a series of approximately V-shaped notches on the underside of the blade body 120 when viewed from the front side of the blade body 120, thereby providing a series of stepped steps on the underside of the blade body 120. In Figure 5, the portion indicated by the solid line has stepped steps extending in the longitudinal direction of the blade body 120. This allows the crossbeam blade 123A indicated by the solid line to function as a blade. On the other hand, the portion indicated by the dashed line at the position where the crossbeam blade 123A is located is smooth when viewed from the left or right side, and does not function as a blade. The cutting edges of the gang blades 123A may or may not all be the same, but are generally between 30° and 75°. In this embodiment, although not necessarily limited to this, the cutting edges of the gang blades 123A are all approximately 60°. The crossbeam blade body 123 included in the crossbeam blade 123 is substantially V-shaped when the blade body 120 is viewed from the front. In each of the substantially V-shaped crossbeam blade bodies 123A, the apex of the substantially V-shape is on a plane that includes the axis of the blade body 120 in the curved portion 121 (that is, in this embodiment, a vertical plane that divides the blade body 120 into two equal halves), and each crossbeam blade body 123A is symmetrical with respect to that plane.

[0019] Next, a method of using the above-described carving knife 100 will be described. A user using the carving knife 100 grips the handle 110 of the carving knife 100. The handle 110 of the carving knife 100 itself is no different from the handles of conventional carving knives, so the way of holding the handle 110 of the carving knife 100 can be the same as before. Depending on the method of carving an object with the carving knife 100, the user can, and usually does, change the way of holding the handle 110. FIG. 6 is a perspective view showing a state in which a user holds the handle 110 in his / her right hand, which is his / her dominant hand.

[0020] A user holding the carving knife 100 holds an object 300 to be worked with the carving knife 100 in the left hand, as shown in FIG. 7, and brings the blade 120 of the carving knife 100 into contact with the object 300. The method of using the carving knife 100 shown in Figure 7 involves continuously alternating between push-cutting and pull-cutting using any two of sides 122X, 122Y, and 122Z of the triangular pyramidal portion 122 provided at the tip of the blade body 120, i.e., any two of the three triangular pyramidal blades. Generally, sides 122X and 122Y, which have the same cutting angle, are selected as the blades to be used when continuously alternating between push-cutting and pull-cutting. This selection can be made by rotating the handle 110 around its axis. In this case, the user brings the middle of the blade body 120 into contact with the tip of the thumb L1 of the left hand holding the object 300, and places, for example, the middle finger R3 of the right hand holding the carving knife 100 on the blade body 120 so as to pinch the blade body 120 between the thumb L1 and the right hand. In this state, the user moves the handle 110 of the carving knife 100 with their right hand in the direction of the arrow shown in Fig. 7, using the part of the thumb L1 of the left hand that is in contact with the blade body 120 as the fulcrum of the lever. As a result, the triangular pyramid portion 122 at the tip of the blade body 120, which is the point of action, moves back and forth along an arc-shaped route, with the fulcrum at the tip of the thumb L1 of the left hand as the center. During this reciprocating motion, when the triangular pyramid portion 122 moves to one side, the object 300 is pressed and scraped by one of the sides 122X and 122Y, and when the triangular pyramid portion 122 moves to the other side, the object 300 is pressed and scraped by the other of the sides 122X and 122Y. This makes it easy to carve the object 300 with the carving knife 100 even if the object 300 is hard or has a grain. Furthermore, as mentioned above, the apex 122D of the triangular pyramid portion 122 is located slightly above the upper end of the base of the shaft of the blade body 120 relative to the handle 110 in Figure 3(A), so that when a force is applied to the triangular pyramid portion 122, which is the point of action, via the fulcrum, it is easier to control the force.

[0021] Figure 8 shows a different way of using the carving knife 100 from the way shown in Figure 7. In the method of use shown in Figure 8, push-cutting is performed using any one of sides 122X, 122Y, and 122Z of the triangular pyramidal portion 122 provided at the tip of the blade body 120, that is, any one of the three triangular pyramidal blades. Using the portion of side 122Z with a relatively small cutting angle near vertex 122D enables not only push-cutting but also push-cutting. In this case as well, the user holds the handle 110 of the carving knife 100 with the right hand and the object 300 with the left hand. Then, the triangular pyramid portion 122 at the tip of the blade 120 of the carving knife 100 is brought into contact with the object 300. In this state, the user presses the blade 120 with the pad of the thumb L1 of the left hand holding the object 300, and any one of the sides 122X, 122Y, and 122Z of the triangular pyramid portion 122, which moves in the direction indicated by the arrow, presses and cuts the object 300. In Figure 8, the middle finger R3 of the right hand is placed on the blade 120 so that it is positioned to pinch the blade 120 between the thumb L1 and the right hand, but in this case, the middle finger R3 of the right hand does not have much of a role in pinching the blade 120 between the thumb L1 and the left hand. The role of the middle finger R3 of the right hand is to stabilize the blade 120 being pressed by the thumb L1 of the left hand and to return the blade 120, which has been pushed out by the thumb L1 of the left hand, to its original position before being pushed out. When the carving knife 100 is used in this manner, it is difficult to apply force to the blade 120 when returning the blade 120. Therefore, when the carving knife 100 is used in this manner, it is either pressed to scrape the object 300 or pressed to cut only when the portion of the edge 122Z near the vertex 122D is used.

[0022] Figure 9 shows a different usage mode of the carving knife 100 from that shown in Figures 7 and 8. In the usage method shown in Figure 9, a groove is cut into the object 300 using the crossbeam cutting edge 123 provided on the blade body 120. In this case, too, the user holds the handle 110 of the carving knife 100 with his right hand and the object 300 with his left hand. Then, the triangular pyramid portion 122 at the tip of the blade 120 of the carving knife 100 is brought into contact with the object 300. The index finger R2 of the right hand is placed on the handle 110 so that force can be easily applied to the handle 110. In this case, the left hand has no role other than holding down the target 300. With the target 300 firmly held in the left hand at the desired position, the user moves the blade 120 back and forth in a straight line along its length, as indicated by the arrow in the figure. At this time, the gong blade 123 of the blade 120 abuts against the target 300. This creates a groove in the target 300 by the gong blade 123. Because the gong blade 123 is located outside the curved portion 121 of the blade 120, the user can easily apply a large force to the target 300. In addition, the width of the groove can be adjusted by using which part of the gong blade 123, which has a certain length along the blade 120. If a hole or aperture has already been drilled in the object 300, this use of the carving knife 100 can enlarge the diameter of the hole or aperture and also enable more detailed work to be done on the inner surface of the hole or aperture. When working on the inner surface of such a hole or aperture, or when working on a location that would be difficult to work on with a straight blade, it is often useful that the blade body 120 is curved at the curved portion 121. This advantage also applies when using the carving knife 100 as described with reference to Figures 7 and 8. [Explanation of symbols]

[0023] 100 carving knives 110 patterns 120 Blade 121 Curved section 122 Triangular pyramid part 122A, 122B, 122C, 122D Vertices 122X, 122Y, 122Z sides (triangular pyramid blade) 123 Ganki Blade

Claims

1. A carving knife comprising a rod-shaped handle sized and shaped to be held in one hand, and a rod-shaped metal blade body with a base end fixed to the handle and a blade on a part thereof, The tip of the blade is provided with a triangular pyramid portion having a triangular pyramid shape with the tip of the blade as the apex, Each of the three sides extending from the apex of the triangular pyramid portion is a triangular pyramid blade, At least one-third of the tip of the blade is curved in an arc shape, Two of the three triangular pyramidal blades have equal blade angles, and the other has a smaller blade angle; The two triangular pyramidal blades having the same cutting angle are positioned inside the curved portion and are positioned symmetrically with respect to a plane including the center line of the blade body in the curved portion. Carving knife.

2. A carving knife comprising a rod-shaped handle sized and shaped to be held in one hand, and a rod-shaped metal blade body with a base end fixed to the handle and a blade on a part thereof, The tip of the blade is provided with a triangular pyramid portion having a triangular pyramid shape with the tip of the blade as the apex, Each of the three sides extending from the apex of the triangular pyramid portion is a triangular pyramid blade, The blade body is designed so that its thickness gradually increases from the tip side to the base end side within a predetermined range from the base end of the triangular pyramid portion toward the base end thereof, and a plurality of successive blades with blade angles of 30° to 75° are provided on one surface of the blade body as viewed from the front within the predetermined range in which the thickness gradually increases from the tip side to the base end side. Carving knife.

3. Two of the three triangular pyramidal blades have equal blade angles, and the other blade angle is smaller than the other. The carving knife according to claim 2.

4. At least one-third of the tip of the blade body is curved in an arc shape, Two of the three triangular pyramidal blades have equal blade angles, and the other has a smaller blade angle; The two triangular pyramidal blades having the same cutting angle are positioned inside the curved portion and are positioned symmetrically with respect to a plane including the center line of the blade body in the curved portion. The carving knife according to claim 2.

5. The blade body is designed so that its thickness gradually increases from the tip side to the base end side within a predetermined range from the base end of the triangular pyramid portion toward the base end thereof, and a plurality of successive blades with blade angles of 30° to 75° are provided on one surface of the blade body as viewed from the front within the predetermined range in which the thickness gradually increases from the tip side to the base end side. The carving knife according to claim 1.

6. The blades each having a blade angle of 30° to 75° and each of which is included in the gang blade are substantially V-shaped when viewed from the front of the blade body. The carving knife according to claim 2 or 5.

7. The crossbeam blade is positioned outside the curved portion. The carving knife according to claim 4 or 5.

8. The blades each having a blade angle of 30° to 75° are substantially V-shaped when viewed from the front of the blade body, Furthermore, each of the V-shaped blades having a blade angle of 30° to 75° is configured so that the apex of the V-shape is on a plane including the center line of the blade body in the curved portion. The carving knife according to claim 7.

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