Blades of cooking knives and cooking knives

Abstract

To provide a sword body of a cooking cutter which has excellent sharpness and is superior in operability and durability.SOLUTION: A material constituting a sword body 10 is tungsten carbide-based hard metal, and a maximum value of the blade thickness being a thickness of the sword body 10 is 1.1 mm to 1.4 mm. In addition, a first edge angle θ1 can be 18 to 24 degrees, whereas a second edge angle θ2 can be 6.0 to 8.0 degrees, and a first blade width D1 can be 0.1 mm to 0.6 mm, whereas a second blade width D2 can be 4.0 mm to 8.0 mm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a blade of a cooking cutlery and a cooking cutlery provided with the blade. [Background Art]

[0002] For cooking cutlery such as kitchen knives and knives, good sharpness and good operability such as easy center of gravity adjustment when gripping and operating by hand are issues that should always be desired. Conventionally, steel blades have been widely used as blades for cooking cutlery, but steel blades are prone to wear and have poor durability. [Summary of the Invention] [Problem to be Solved by the Invention]

[0003] In view of the above circumstances, an object of the present invention is to provide a blade of a cooking cutlery that has good sharpness and is excellent in operability and durability, and a cooking cutlery provided with the blade. [Means for Solving the Problem]

[0004] In order to solve the above problem, a blade of a cooking cutlery according to the present invention is characterized in that: The material constituting the blade is a tungsten carbide-based cemented carbide, the maximum value of the blade thickness, which is the thickness of the blade, is 1.1 mm or more and 1.4 mm or less.

[0005] In conventional blades of cooking cutlery, the maximum blade thickness exceeds at least 2 mm. Compared with this, the maximum blade thickness of 1.1 mm or more and 1.4 mm or less in the blade of the present invention is a very small value. Since tungsten carbide-based cemented carbide has high rigidity, deformation such as bending is less likely to occur even when the maximum blade thickness is set to a very small value of 1.1 mm or more and 1.4 mm or less. Therefore, sharp sharpness can be achieved by setting the blade thickness to a very small value of 1.1 mm or more and 1.4 mm or less while suppressing deformation. The most preferable maximum blade thickness is 1.2 mm.

[0006] Furthermore, because tungsten carbide cemented carbide has high hardness, the blade constructed with this material is highly wear-resistant and durable. Generally, materials with high hardness have high density, so constructing a blade with such a material can make the blade heavy, potentially reducing handling and making it difficult to maintain balance. In contrast, this construction has a very small blade thickness, so even when using a material with high hardness and density, it is possible to prevent the weight from becoming excessive.

[0007] Therefore, this configuration makes it possible to provide a kitchen knife blade that is sharp, easy to handle, and highly durable.

[0008] The blade of the cooking knife according to the present invention has the above configuration in addition to the above configuration, "At a certain point on the cutting edge, the shape of the cross-section obtained by cutting the blade in the direction normal to the cutting edge is symmetric with respect to a straight line L extending from the cutting edge to the center of the spine." In the cross-sectional shape, the angle formed by both sides extending from the cutting edge to the crest changes in three stages, starting from the cutting edge side: the first cutting edge angle, the second cutting edge angle, and the third cutting edge angle. The first cutting edge angle is 18 degrees or more and 24 degrees or less, the second cutting edge angle is 6.0 degrees or more and 8.0 degrees or less, and the third cutting edge angle is smaller than the second cutting edge angle. The first blade width, which is the length in the straight line L direction between the point where the angle formed by both sides changes from the first blade angle to the second blade angle and the cutting edge, is 0.1 mm or more and 0.6 mm or less, and the second blade width, which is the length in the straight line L direction between the point where the angle formed by both sides changes from the second blade angle to the third blade angle and the cutting edge, is 4.0 mm or more and 8.0 mm or less.

[0009] In addition to the maximum blade thickness, by setting the first cutting angle, second cutting angle, first cutting width, and second cutting width to the specific ranges described above, it is possible to provide a blade that is comprehensively superior in terms of operability, initial sharpness, sharpness retention, machinability, and impact resistance, as will be explained in detail later. Ideally, the first cutting angle should be 20 degrees, the first cutting width 0.3 mm, the second cutting angle 7.0 degrees, and the second cutting width 6.0 mm.

[0010] Next, the cooking blade according to the present invention is "The blade of the cooking knife described above is supported by the handle via a tang."

[0011] This is the configuration of a cooking knife equipped with the blade described above. [Effects of the Invention]

[0012] As described above, the present invention provides a cooking knife blade that is sharp, easy to handle, and durable, as well as a cooking knife equipped with the blade. [Brief explanation of the drawing]

[0013] [Figure 1] This is an explanatory diagram of the shape of the cross-section of the sword blade. [Figure 2] (a) is a plan view of the blade and tang, and (b) is a front view of a kitchen knife in which the blade is supported by the handle via the tang. [Figure 3] (a) is a cross-sectional view along line AA in Figure 2(b), and (b) is a cross-sectional view along line BB in Figure 2(b). [Figure 4] This is an explanatory diagram of the test using a sharpness testing machine. [Figure 5] This is an explanatory diagram for impact resistance testing. [Figure 6] This graph shows the test results for the durability of sharpness. [Figure 7] This graph shows the results of analysis using a taste sensor. [Figure 8] This graph compares some of the analysis results from a taste sensor with the analysis results for other companies' products. DETAILED DESCRIPTION OF THE INVENTION

[0014] A cooking blade 1, which is a specific embodiment of the present invention, and a blade body 10 thereof will be described with reference to the drawings. In the cooking blade 1, the blade body 10 is supported by a handle portion 40 via a tang 30. The cooking blade 1 of the present embodiment is a kitchen knife.

[0015] The blade body 10 is made of a tungsten carbide-based cemented carbide. The tungsten carbide-based cemented carbide is a composite material in which tungsten carbide particles are bound by a metal constituting a binder phase. The cemented carbide of the present embodiment is a WC-Ni-Cr-based cemented carbide in which the metals constituting the binder phase are nickel and chromium. When the content of nickel in a tungsten carbide-based cemented carbide using nickel as the binder phase reaches a certain level or more, the cemented carbide loses magnetism to become a non-magnetic cemented carbide, and at the same time, the corrosion resistance thereof is improved. Further, when chromium is contained in the binder phase, the corrosion resistance is further improved. The WC-Ni-Cr-based cemented carbide used in the present embodiment is a non-magnetic cemented carbide, and is manufactured by powder metallurgy using powder of the following composition as a raw material. WC: 69.76% by mass Ni: 27.00% by mass Cr3C2: 3.24% by mass

[0016] The physical property values of the WC-Ni-Cr-based cemented carbide constituting the blade body 10 of the present embodiment are as follows. Specific gravity: 12.30 to 12.88 Rockwell hardness: HRA 83.0 to 85.0 Transverse rupture strength: 250 to 380 kgf / mm 2 The above is the end of the composition WC particle diameter: 1.0 μm Young's modulus: 435 GPa Poisson's ratio: 0.25

[0017] Here, the specific gravity was measured by the Archimedes method in accordance with the Japan Cemented carbide Manufacturers Association Standard CIS028B-2007. Young's modulus and Poisson's ratio were measured by an ultrasonic pulse method.

[0018] The blade 10 has a shape in which the cutting edge 15, where the cutting edge is formed, forms a continuous cutting edge line that curves from the base 12 to the tip 11 (sword tip). The tang 30 is formed integrally with the blade 10 and extends in a flat shape on the opposite side of the tip 11, with a width narrower than the width of the blade 10. The portion of the tang 30 on the spine 16 side of the periphery is continuous with the spine 16 of the blade 10.

[0019] The blade thickness (thickness of the blade 10) increases from the tip 11 towards the base 12, and also from the cutting edge 15 towards the spine (back) 16. Therefore, the spine 16 side of the boundary with the tang 30 is the part of the blade with the greatest blade thickness. If we refer to the blade thickness of this part as the "maximum blade thickness T", then the maximum blade thickness T is 1.1 mm or more and 1.4 mm or less. In this embodiment, the thickness of the tang 30 is the same as the maximum blade thickness T of the blade 10. Note that the maximum blade thickness in this embodiment corresponds to the "maximum blade thickness" of the present invention.

[0020] The cross-section obtained by cutting the blade 10 at a certain point along the cutting edge in the direction normal to the cutting edge (hereinafter referred to as the "blade cross-section") has a special shape. That is, as shown in Figure 1, the blade cross-section is symmetrical with respect to the straight line L extending from the cutting edge 15 to the center of the spine 16, and the angles formed by the two sides 21 and 22 extending from the cutting edge 15 to the spine 16 in the outer shape of the blade cross-section change in three stages, starting from the cutting edge 15 side: the first cutting edge angle θ1, the second cutting edge angle θ2, and the third cutting edge angle θ3. The first cutting edge angle θ1 is between 18 degrees and 24 degrees, the second cutting edge angle θ2 is between 6 degrees and 8 degrees, and the third cutting edge angle θ3 is smaller than the second cutting edge angle θ2.

[0021] Furthermore, in the cross-section of the blade, the first cutting width D1, which is the length in the straight line L direction between the cutting edge 15 and point P1 where the angle between both sides 21 and 22 changes from the first cutting angle θ1 to the second cutting angle θ2, is 0.1 mm or more and 0.6 mm or less, and the second cutting width D2, which is the length in the straight line L direction between the cutting edge 15 and point where the angle between both sides 21 and 22 changes from the second cutting angle θ2 to the third cutting angle θ3, is 4.0 mm or more and 8.0 mm or less.

[0022] Once the first cutting edge angle θ1, first cutting edge width D1, second cutting edge angle θ2, and second cutting edge width D2 are determined, the third cutting edge angle θ3 at the blade cross-section where the blade thickness is the maximum blade thickness T is uniquely determined. This third cutting edge angle θ3 is also used in blade cross-sections where the blade thickness is not the maximum blade thickness T.

[0023] In Figure 1, the magnitudes of the first cutting edge angle θ1, the second cutting edge angle θ2, and the third cutting edge angle θ3, as well as the relationship between the lengths of the first cutting edge width D1 and the second cutting edge width D2, are exaggerated to clearly show the change in angle. Examples of actual blade cross-sections are shown in Figures 3(a) and 3(b). Figure 3(a) is a cross-sectional view of the blade 10 cut by line AA in Figure 2(b), i.e., a line perpendicular to the tangent TL1 of the cutting edge, and Figure 3(b) is a cross-sectional view of the blade 10 cut by line BB in Figure 2(b), i.e., a line perpendicular to the tangent TL2 of the cutting edge. As can be seen from these cross-sectional views, except for the immediate vicinity of the tip 11, in the cross-section of the blade obtained by cutting the blade 10 in the direction normal to the cutting edge at any point along the cutting edge, the first cutting angle θ1, first cutting width D1, second cutting angle θ2, second cutting width D2, and third cutting angle θ3 are the same, and only the length in the straight line L direction of the portion where the angle between both sides 21 and 22 is the third cutting angle θ3 changes.

[0024] Next, we will explain the rationale for setting the desirable ranges for the maximum blade thickness T, first blade angle θ1, first blade width D1, second blade angle θ2, and second blade width D2 to the ranges described above.

[0025] <Consideration of blade thickness> For kitchen knives S1 to S8, each with a blade 10 supported on a handle 40, the first blade angle θ1 was kept constant at 20 degrees, the first blade width D1 at 0.3 mm, the second blade angle θ2 at 7.0 degrees, and the second blade width D2 at 6.0 mm, while the blade thickness varied from 0.9 mm to 1.6 mm, the rigidity and weight were evaluated. Rigidity was evaluated by the degree of deformation (bend) when the knife was held in the hand and placed on a cutting board. Weight was evaluated by whether the weight was easy to handle and to maintain balance when holding and moving the knife in the hand. Rigidity and weight were each evaluated by assigning points as follows. The results are shown in Table 1. Very good: 5 points Good: 4 points Normal: 3 points Defective: 2 points Very poor: 1 point

[0026] [Table 1]

[0027] Knife S1, with a maximum blade thickness T of 0.9mm, had a blade 10 that was easily bent, lacking practical rigidity, and felt too light in the hand, making it difficult to find the center of gravity and difficult to handle. Knives S7 and S8, with a maximum blade thickness T of 1.5mm or more, had good rigidity, but were too heavy to hold, making it difficult to find the center of gravity, and were very poor in terms of weight. Considering both rigidity and weight, a maximum blade thickness T in the range of 1.1mm to 1.4mm is desirable, 1.1mm to 1.3mm is more desirable, and 1.2mm, which gives the highest total score, is the most desirable.

[0028] Next, we present the results of an evaluation of the operability of the first blade angle θ1, first blade width D1, second blade angle θ2, and second blade width D2, based on the evaluation of the operability by subjects who cut food with a kitchen knife. In the operability evaluation, five subjects cut carrots, tomatoes, and onions with the kitchen knife and evaluated the operability on a score basis as follows. Operability was evaluated as "very good" when there was no feeling of crushing the object and the blade 10 could cut with good responsiveness to movement, and points were deducted depending on the degree of operability. Very good: 5 points Good: 4 points Normal: 3 points Defective: 2 points Very poor: 1 point

[0029] <Consideration of the first cutting edge angle θ1> The operability of knives S11 to S16, each with a blade 10 supported on a handle 40, was evaluated. The blades were kept constant with a first blade width D1 of 0.3 mm, a second blade angle θ2 of 7.0 degrees, a second blade width D2 of 6.0 mm, and a maximum blade thickness T of 1.2 mm, while the first blade angle θ1 was varied from 18 degrees to 40 degrees. The results are shown in Table 2.

[0030] [Table 2]

[0031] When the first cutting edge angle θ1 exceeded 28 degrees, the operability deteriorated sharply. A first cutting edge angle θ1 of 18 degrees or more and 24 degrees or less is desirable, with 20 degrees being the most desirable as it yielded the highest evaluation score. Furthermore, it was difficult to manufacture blades 10 with a first cutting edge angle θ1 of less than 18 degrees.

[0032] <Consideration of the first cutting edge width D1> The operability of knives S21 to S24, each with a blade 10 supported on a handle 40, was evaluated. The blades were kept constant at a first cutting angle θ1 of 20 degrees, a second cutting angle θ2 of 7.0 degrees, a second cutting width D2 of 6.0 mm, and a maximum blade thickness T of 1.2 mm, while the first cutting width D1 varied from 0.1 mm to 0.9 mm. The results are shown in Table 3.

[0033] [Table 3]

[0034] The first cutting edge width D1 is preferably between 0.1 mm and 0.6 mm, with 0.3 mm being the most desirable as it yields the highest evaluation score.

[0035] <Consideration of the second blade angle θ2> The operability of knives S31 to S37, each with a blade 10 supported on a handle 40, was evaluated. The blades were kept constant at a first cutting angle θ1 of 20 degrees, a first cutting width D1 of 0.3 mm, a second cutting width D2 of 6.0 mm, and a maximum blade thickness T of 1.2 mm, while the second cutting angle θ2 varied from 3.0 degrees to 9.0 degrees. The results are shown in Table 4. The third cutting angle θ3, determined from the first cutting angle θ1, first cutting width D1, second cutting angle θ2, second cutting width D2, and maximum blade thickness T, is also shown in Table 4.

[0036] [Table 4]

[0037] Knife S37, with a second cutting edge angle θ2 of 9.0 degrees, exhibited significant cutting resistance, causing the carrot to split. Furthermore, knives S31-S33, with a second cutting edge angle θ2 of 5.0 degrees or less, felt as if the material being cut was sticking to the blade 10. A second cutting edge angle θ2 of 6.0 degrees or more and 8.0 degrees or less is desirable, with 7.0 degrees being the most desirable, as it yielded the highest evaluation score. Additionally, when the second cutting edge angle θ2 was between 6.0 degrees and 8.0 degrees, the third cutting edge angle θ3 was between 0.48 degrees and 0.80 degrees.

[0038] <Consideration of the second cutting edge width D2> The operability of knives S41 to S45, each with a blade 10 supported on a handle 40, was evaluated. The blades were kept constant at a first cutting angle θ1 of 20 degrees, a first cutting width D1 of 0.3 mm, a second cutting angle θ2 of 7.0 degrees, and a maximum blade thickness T of 1.2 mm, while the second cutting width D2 varied from 2.0 mm to 9.0 mm. The results are shown in Table 5. The third cutting angle θ3, determined from the first cutting angle θ1, first cutting width D1, second cutting angle θ2, second cutting width D2, and maximum blade thickness T, is also shown in Table 5.

[0039] [Table 5]

[0040] Knife S41 with a second blade width D2 of 2.0 mm and knife S45 with a second blade width D2 of 9.0 mm both exhibited high resistance. A second blade width D2 of 4.0 mm or more and 8.0 mm or less is desirable, with 6.0 mm being the most desirable as it yielded the highest evaluation score. Furthermore, when the second blade width D2 was between 4.0 mm and 8.0 mm, the third blade angle θ3 was between 0.26 degrees and 0.98 degrees.

[0041] The above evaluation focused on operability based on human perception. However, the following shows the results of other evaluations, including initial sharpness using a sharpness tester, sharpness retention using a sharpness tester, machinability, and impact resistance. For these evaluations, as mentioned above, we used knives S11 to S16, in which the blade 10 was supported on the handle 40, with a constant first blade width D1 of 0.3 mm, second blade angle θ2 of 7.0 degrees, second blade width D2 of 6.0 mm, and maximum blade thickness T of 1.2 mm, while the first blade angle θ1 was varied from 18.0 degrees to 40.0 degrees.

[0042] <Evaluation using a sharpness testing machine> As shown in Figure 4(a), the blade 10 of a kitchen knife with the tip 11 facing downwards was held in the clamp 51 of the testing machine, and the test was conducted by moving the knife up and down to cut the paper while a constant load was applied from the blade 15 to the stack of paper 50. A blade sharpness testing machine manufactured by Marutomi Seikou Co., Ltd. was used for the test. A stack of paper 50, consisting of a predetermined number of sheets of paper of a predetermined thickness, was bent by being sandwiched between one cylindrical pin 55 and two rollers 56 as shown in Figure 4(b), and the blade 15 was brought into contact with the stack of paper 50 so that it faced the cylindrical pin 55. As the paper was cut by moving the knife up and down, it separated from the blade 10, and since no friction occurred between the cut paper and the blade 10, the force with which the blade 15 was in contact with the stack of paper 50 could be kept constant, and only the cutting performance of the blade 15 could be evaluated.

[0043] Using this sharpness testing machine, we evaluated the initial sharpness and the persistence of the sharpness. In the initial sharpness test, we used a stack of paper 50, equivalent to newspaper with a width of 7.5 mm, and applied a load of 8.0 ± 0.2 N from the blade tip 15 to the stack of paper 50. We then moved the knife up and down 20 mm in one direction, for a total of 40 mm in both directions. We calculated the average cutting distance per return from the number of sheets cut (cutting distance) after 10 returns and evaluated it with a score as follows. The evaluation results are shown in Table 6 below. 2.6mm or more: 5 points 2.0mm or more, less than 2.5mm: 4 points 1.5mm or more, less than 2.0mm: 3 points 1.0mm or more, less than 1.5mm: 2 points Less than 1.0 mm: 1 point

[0044] The sharpness retention test used a stack of 7.5mm wide matte coated paper (50 sheets), and applied a load of 8.0±0.2N from the blade tip (15) to the stack of paper (50 sheets). The knife was then moved up and down 40mm in one direction and 80mm back and forth. The cumulative cutting distance until the cutting distance per back and forth reached 0.5mm was calculated. As cutting continues, the sharpness of the blade gradually decreases. However, blades that do not lose sharpness easily, i.e., blades with high sharpness retention, have a longer cumulative cutting distance. Figure 6 shows graphs plotting the cutting distance per back and forth against the cumulative cutting distance for each knife S11 to S16. The cumulative cutting distance until the cutting distance per back and forth reaches 0.5mm is longer as the first blade angle θ1 decreases. Therefore, a smaller first blade angle θ1 indicates higher sharpness retention.

[0045] Furthermore, the cumulative cutting distance until the cutting distance per round trip reached 0.5 mm was evaluated using a scoring system as follows. The evaluation results are shown in Table 6 below. 4000mm or more: 5 points 3000mm or more, less than 4000mm: 4 points 2000mm or more, less than 3000mm: 3 points 1000mm or more, less than 2000mm: 2 points Less than 1000mm: 1 point

[0046] <Evaluation of processability> For the blade 10, which was sharpened using a sharpening device to achieve a predetermined first cutting angle θ1, first cutting width D1, second cutting angle θ2, second cutting width D2, maximum cutting thickness T, and third cutting angle θ3, the amount of burrs generated during sharpening and the ease of burr removal were used as indicators of machinability and were evaluated with scores as follows. The evaluation results are shown in Table 6 below. Good: 3 points Normal: 2 points Defective: 1 point

[0047] <Evaluation of impact resistance> As shown in Figure 5(a), a knife was supported by an arm 60 that rotates around an axis 61, and the knife was dropped from a height H by the natural rotation of the arm 60, causing the blade tip 15 to collide with a stainless steel round bar 65 (made of SUS304, diameter Φ10 mm). Due to the impact of this collision, a chip 19 was created on the blade tip 15 of the blade 10, as shown in Figure 5(b). The area of ​​the chip 19 was determined from its length A and depth B. The average value of the chip area 19 obtained from multiple tests was used as an indicator of chip resistance, i.e., impact resistance, and was evaluated with a score as follows. 0.5mm 2 Less than: 3 points 0.5mm 2 Above, 1.0 mm 2 Less than: 2 points 1.0mm 2 Total: 1 point

[0048] Table 6 shows the evaluation results for initial sharpness, sharpness retention, workability, and impact resistance, along with the human evaluation results for operability mentioned above. Table 6 also shows the overall evaluation, which is the sum of the scores for each of these evaluations.

[0049] [Table 6]

[0050] Based on the overall evaluation, the first cutting edge angle θ1 is desirable to be between 18.0 degrees and 24 degrees, with 20 degrees being the most desirable as it receives the highest evaluation score.

[0051] Based on the above evaluation, the most desirable knife overall was S12, which had a first blade angle θ1 of 20 degrees, a first blade width D1 of 0.3 mm, a second blade angle θ2 of 7.0 degrees, a second blade width D2 of 6.0 mm, and a maximum blade width of 1.2 mm. This is identical to knives S4, S22, S35, and S43, with a third blade angle θ3 of 0.64 degrees. Using this knife, samples of carrots, onions, roast beef, and tuna sashimi were cut, and the sweetness, umami, bitterness, sourness, and saltiness were analyzed using a taste sensor. The taste sensor "LEO" manufactured by AISSY Co., Ltd. was used for the analysis, and the analysis was performed by the company. Furthermore, for knives manufactured by other companies, Company A and Company B, which are approximately the same size and shape as the knife of this embodiment, the same samples obtained by cutting the same object as described above were analyzed for sweetness, umami, bitterness, sourness, and saltiness. The blades of both Company A and Company B knives are made of stainless steel. The analysis results are shown in Figure 7.

[0052] Furthermore, Figures 8(a) to 8(d) show graphs comparing the analytical values ​​of samples cut with knives manufactured by Company A, Company B, and the knife of this embodiment for the sweetness of carrots, the bitterness of onions, the umami of roast beef, and the umami of tuna sashimi, respectively. For all analytical values, there was a significant difference between the samples cut with the knife of this embodiment and those cut with knives manufactured by other companies. The results showed that the samples cut with the knife of this embodiment had higher sweetness in carrots, lower bitterness in onions, and higher umami in roast beef and tuna sashimi compared to the samples cut with knives manufactured by other companies. It has long been said that the sharpness of cooking knives affects the taste of the food they cut, but based on the above analytical results, it is thought that cutting with the knife of this embodiment enhances the taste that is pleasing to humans.

[0053] As described above, according to this embodiment, by setting the first blade angle θ1, first blade width D1, second blade angle θ2, second blade width D2, maximum blade thickness T, and the third blade angle θ3 determined by these within a predetermined range, it is possible to provide a cooking knife 1 that is comprehensively superior in terms of operability, initial cutting performance, cutting performance retention, workability, and impact resistance. Furthermore, by cutting food with the cooking knife 1 of this embodiment, the taste that is pleasing to humans is enhanced, making the food taste better.

[0054] Furthermore, in the immediate vicinity of the tip 11, the third cutting edge angle θ3 is not formed in the portion where the length in the straight line L direction of the blade cross-section is less than or equal to the sum of the first cutting edge width D1 and the second cutting edge width D2. In the cooking knife 1, the immediate vicinity of the tip 11 is a portion used for a different cutting purpose than the rest of the cutting edge 15. The present invention, including this embodiment, aims to improve the sharpness, operability, and durability of the cutting edge 15 in the range where the third cutting edge angle θ3 can be formed.

[0055] When the length of the straight line L of the blade cross-section is equal to the sum of the first blade width D1 and the second blade width D2, that is, at the boundary between the part where the third blade angle θ3 can be formed and the part where it cannot, the blade thickness on the spine 16 side can be determined from the first blade angle θ1, the first blade width D1, the second blade angle θ2, and the second blade width D2. This blade thickness is defined as the minimum blade thickness t. For example, when the maximum blade thickness T is 1.2 mm, the first blade angle θ1 is 20 degrees, the first blade width D1 is 0.3 mm, the second blade angle θ2 is 7.0 degrees, and the second blade width D2 is 6.0 mm, that is, when each is the most desirable value, the minimum blade thickness is 0.80 mm. In such a blade 10, the blade thickness on the spine 16 side gradually decreases from the maximum blade thickness T of 1.2 mm at the boundary with the tang 30 to the minimum blade thickness of 0.80 mm, and further decreases towards the tip 11.

[0056] The minimum blade thickness is achieved when the first cutting angle is 18 degrees, the first cutting width is 0.1 mm, the second cutting angle is 6.0 degrees, and the second cutting width is 4.0 mm, that is, when each of these values ​​is at its minimum within the desired range, and the minimum blade thickness is 0.44 mm. In this case, the blade thickness gradually decreases on the spine 16 side from the maximum blade thickness T1.1 mm to 1.4 mm at the boundary of the tang 30 to the minimum blade thickness t0.44 mm, and further decreases on the spine 16 side towards the tip 11.

[0057] On the other hand, the minimum blade thickness takes its maximum value when the first cutting angle is 24 degrees, the first cutting width is 0.6 mm, the second cutting angle is 8.0 degrees, and the second cutting width is 8.0 mm, that is, when each is the maximum value within the desired numerical range, the minimum blade thickness t is 1.29 mm. Since this value exceeds the minimum value of the maximum blade thickness, in the range where the maximum blade thickness T at the boundary of the tang 30 is between 1.1 mm and 1.29 mm, the blade thickness is constant up to the point where the length in the straight line L direction of the cross-section of the blade is equal to the sum of the first cutting width D1 and the second cutting width D2, and the blade thickness on the spine 16 side gradually decreases toward the tip 11. In the range where the maximum blade thickness T at the boundary of the tang 30 exceeds 1.29 mm and is between 1.4 mm, the blade thickness gradually decreases toward the spine 16 side from the maximum blade thickness to the minimum blade thickness t of 1.29 mm, and further gradually decreases toward the tip 11.

[0058] Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to the above embodiments, and various improvements and design changes are possible without departing from the spirit of the present invention.

[0059] For example, in the above embodiment, a kitchen knife was shown as the cooking blade 1, but it is not limited to this, and a cooking knife may also be used. Also, in the above embodiment, a cooking blade 1 with a curved blade edge was shown, but the present invention can also be applied to cooking blades with a straight blade edge. [Explanation of symbols]

[0060] 1. Cooking knives 10 blade 15 cutting edge 16 peaks 30 Core 40 Handle θ1 First blade angle θ2 Second blade angle θ3 Third blade angle D1 First blade width D2 Second blade width T Maximum blade thickness (maximum value of blade thickness)

Claims

1. The material that makes up the blade is a tungsten carbide-based cemented carbide. The maximum value of the blade thickness, which is the thickness of the aforementioned blade, is 1.1 mm or more and 1.4 mm or less, At a certain point along the cutting edge, the shape of the cross-section obtained by cutting the blade in the direction normal to the cutting edge is symmetric with respect to a straight line L extending from the cutting edge to the center of the spine. In the cross-sectional shape, the angle formed by both sides extending from the cutting edge to the crest changes in three stages, starting from the cutting edge side: the first cutting edge angle, the second cutting edge angle, and the third cutting edge angle. The first cutting edge angle is 18 degrees or more and 24 degrees or less, the second cutting edge angle is 6.0 degrees or more and 8.0 degrees or less, and the third cutting edge angle is smaller than the second cutting edge angle. The first blade width, which is the length in the straight line L direction between the point where the angle formed by both sides changes from the first blade angle to the second blade angle and the cutting edge, is 0.1 mm or more and 0.6 mm or less, and the second blade width, which is the length in the straight line L direction between the point where the angle formed by both sides changes from the second blade angle to the third blade angle and the cutting edge, is 4.0 mm or more and 8.0 mm or less. A cooking knife blade characterized by the following features.

2. The blade of the cooking knife described in claim 1 is supported by the handle via a tang. A cooking knife characterized by the following features.

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