pencil

Abstract

To provide a pencil capable of suppressing deterioration in the surface quality of the pencil after cutting, even when wood not containing a material that imparts easy sharpening properties is used.SOLUTION: A pencil 10 includes a lead 14 having a diameter RC of 3.0 mm or more, and a shaft 12 that covers the lead 14 and is made of wood that does not contain any material that imparts easy sharpening properties and has an air-dry specific gravity of less than 0.6.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to pencils. [Background technology]

[0002] Patent Document 1 discloses that by adding at least a naturally occurring filler and a naturally occurring binder to the shaft material composition that forms the shaft of a pencil, the shaft can be given the same ease of sharpening as a conventional wooden shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-059431 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have discovered that, particularly when wood with an air-dry specific gravity of less than 0.6 and no material that imparts sharpness is used, the cutting resistance of the shaft becomes relatively high when the pencil is sharpened, and as a result, the inner core covered by the shaft becomes more likely to break. In other words, when wood that does not contain a material that imparts sharpness is used, the surface quality of the pencil after cutting deteriorates. In this regard, Patent Document 1 does not consider any technology for reducing the cutting resistance of the shaft when sharpening a pencil when wood that does not contain a material that imparts sharpness is used.

[0005] The present disclosure has been made in consideration of the above, and provides a pencil that can suppress deterioration in the surface quality of the pencil after cutting, even when wood that does not contain a material that imparts ease of sharpening is used. [Means for solving the problem]

[0006] The aspects of the present disclosure are as follows.

[0007] <Aspect 1> A core having a diameter of 3.0 mm or more; a shaft body covering the core and made of wood having an air-dry specific gravity of less than 0.6 and not containing a material that imparts easy cutting properties; A pencil.

[0008] In the first aspect, the lead diameter is 3.0 mm or more, so compared to a pencil having the same dimensions and shape except for a lead diameter of less than 3.0 mm, the volume of the lead cut when the pencil is sharpened is increased. The increased volume of the lead cut reduces the volume of the wood of the shaft cut when the pencil is sharpened. Therefore, when the lead diameter is 3.0 mm or more, the cutting resistance of the wood of the shaft can be reduced, and as a result, the cutting torque can be reduced. This improves the surface quality of the pencil after sharpening.

[0009] <Aspect 2> The cross-sectional shape of the shaft is hexagonal or circular, When the cross-sectional shape of the shaft is hexagonal, the distance between the opposing outer surfaces of the hexagon is 7.4 mm or less, and the diameter of the circumscribed circle is 8 mm or less, When the cross-sectional shape of the shaft is circular, the diameter of the circle is 8 mm or less. 2. The pencil of embodiment 1.

[0010] In the second aspect, a wide range of pencils with improved surface quality can be provided.

[0011] <Aspect 3> The allowable average cutting torque at which cutting can be performed without breaking the core is 10 cN·m or less. A pencil according to aspect 1 or aspect 2.

[0012] In the third aspect, even if a pencil sharpener that is prone to bending and twisting, such as a pocket sharpener, is used, the surface quality of the pencil after cutting can be easily improved. [Effects of the Invention]

[0013] According to an aspect of the present disclosure, a pencil can be provided that can suppress deterioration in the surface quality of the pencil after cutting, even when wood that does not contain a material that imparts ease of sharpening is used. [Brief explanation of the drawings]

[0014] [Figure 1] Figure 1(A) is a front view illustrating a pencil according to this embodiment, having a hexagonal cross-sectional shape; Figure 1(B) is a side view illustrating a pencil according to this embodiment; Figure 1(C) is a cross-sectional view taken along line 1C-1C in Figure 1(A); Figure 1(D) is a front view illustrating a pencil having a circular cross-sectional shape as another example of this embodiment; and Figure 1(E) is a side view illustrating a pencil according to another example of this embodiment. [Figure 2] FIG. 1C is a cross-sectional view illustrating a pencil according to a modified example taken along the same line as line 1C-1C in FIG. 1A. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present disclosure will be described below with reference to Figures 1 and 2. In the following description of the drawings, identical or similar parts are designated by the same or similar reference numerals. However, the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each device or component, etc., differ from the actual ones. Therefore, specific thicknesses and dimensions should be determined with reference to the following explanation. Furthermore, parts with different dimensional relationships and ratios are included between the drawings. Furthermore, unless otherwise specified in the specification, the number of each component element of the present disclosure is not limited to one, and multiple elements may be present.

[0016] <Pencil structure> (overview) First, an overview of a pencil 10 according to this embodiment will be described. As shown in Figures 1(A) and 1(B), the pencil 10 has a lead 14 and a shaft 12 that covers the lead 14.

[0017] (shaft body) The shaft 12 is made of wood. As shown in Fig. 1(C), a hollow portion 13 extending along the axial direction (the vertical direction in Fig. 1(C)) is formed inside the shaft 12 for arranging a core 14. The hollow portion 13 is tubular and passes through the shaft 12 in the axial direction.

[0018] As shown in Fig. 1(B), the cross-sectional shape of the shaft 12 of the pencil 10 according to this embodiment is, for example, hexagonal. Fig. 1(B) illustrates the diameter RC of the lead 14, the diameter RA of an imaginary circumscribing circle of the hexagonal shaft 12 in side view, and the inter-face distance W between the opposing outer surfaces of the hexagonal shaft.

[0019] In the present disclosure, the cross-sectional shape of the shaft may be any shape, such as a circle, an ellipse, a rectangle, etc. Figures 1(D) and 1(E) illustrate a pencil 10A having a circular shaft 12A as an example of a pencil having a different cross-sectional shape. Figure 1(E) illustrates the diameter RB of the circular shaft 12A in a side view.

[0020] (Modification of shaft body) In this embodiment, the length of the lead 14 is the same as the entire length of the barrel, but the present disclosure is not limited to this. The length of the lead may be shorter than the entire length of the barrel. For example, the length of the lead may be a length corresponding to a portion of the entire length of the barrel, such as about two-thirds of the entire length of the barrel. By shortening the length of the lead to a length corresponding to a portion of the entire length of the barrel, it is possible to form a pencil in which there is no lead inside the barrel when the lead is completely used up.

[0021] In other words, once the lead is used up, no lead material remains inside the pencil. Therefore, when disposing of or recycling a pencil, there is no need to separate the shaft from the lead, which is made of a different material from the shaft. As a result, it contributes to environmental protection.

[0022] (core) The lead 14 can be arbitrarily set to an ink lead, a color lead, an eraser lead, a cosmetic lead, etc. The lead 14 is disposed in the hollow portion 13 of the shaft body 12.

[0023] [Variations] Next, an overview of a pencil 10B according to a modified example will be described. As shown in Fig. 2, the pencil 10B according to the modified example has a shaft 12B, a lead 14B, a conductive core 16, and a conductive contact portion 18. The pencil 10B according to the modified example functions as an input pen used to input information into an electronic device such as a tablet terminal.

[0024] (shaft body) As in the present embodiment, shaft body 12 is made of wood. Inside shaft body 12, hollow portion 13 is formed extending along the axial direction (the vertical direction in FIG. 2) for arranging core 14 and conductive core 16.

[0025] (core) The lead 14B is a non-conductive lead that does not have electrical conductivity. The lead 14B is arranged in series with the conductive lead 16 in the hollow portion 13 of the shaft 12. The lead 14B is arranged on the opposite side of the conductive lead 16 from the conductive contact portion 18. In other words, in the pencil 10B, the lead 14B is arranged at the tip end, and the conductive contact portion 18 is arranged at the rear end. The conductive lead 16 is arranged between the lead 14B and the conductive contact portion 18. The lead 14B and the conductive lead 16 butt against each other inside the pencil 10B, like the red and blue leads of a vermilion pencil, for example.

[0026] (conductive core) The conductive core 16 is conductive. The conductive core 16 is disposed in the hollow portion 13 of the shaft 12. The conductive core 16 is a non-writing core electrically connected to the conductive contact portion 18. The conductive core 16 is made of, for example, a conductive resin. The rear end of the conductive core 16 is in contact with the conductive contact portion 18. In the axial direction of the pencil 10B, the sum of the length of the conductive contact portion 18 and the length of the conductive core 16 is, for example, 20 mm or more and less than 90 mm.

[0027] (Conductive contact part) The conductive contact portion 18 is provided at one end of the shaft body 12. The conductive contact portion 18 is, for example, a soft contact plug that is conductive. The conductive contact portion 18 is fixed to the shaft body 12 by a fixing member 22. The fixing member is a cylindrical crimping member (ferrule) made of conductive metal or resin. The fixing member is, for example, crimped to the shaft body 12 and the conductive contact portion 18, thereby connecting the shaft body 12 and the conductive contact portion 18.

[0028] Other configurations of the pencil 10B according to the modified example are the same as the configurations of the components with the same names in the pencil 10 according to the present embodiment, and therefore redundant explanations will be omitted. Also, the configuration of the pencil 10B according to the modified example is the same as the configuration of the input pen illustrated in Figure 1 of JP 2023-031218 A, for example.

[0029] <Details of the pencil according to this embodiment> Next, the configuration of the pencil of the present disclosure will be described in detail using the pencil 10 of this embodiment in Figures 1(A) to 1(C) as a representative example. The configuration of the pencil 10A in Figure 1(D) and the configuration of the modified pencil 10B in Figure 2 are also similar to the pencil 10 of this embodiment.

[0030] (core) In this embodiment, the diameter RC of the lead 14 is 3.0 mm or more. Note that the diameter RC of the lead of the present disclosure is not limited to 3.0 mm or more. For example, in a bending strength test according to Japanese Industrial Standards JIS S 6006 (2020), a lead can be used that has a breakage load of more than 10 N when the sample has a support distance of 60 mm.

[0031] (wood) The shaft 12 is made of wood that does not contain any material that imparts ease of cutting, such as paraffin wax, and the air-dry specific gravity of the wood is less than 0.6. Specifically, for example, cypress, camphor tree, ginkgo, tulip tree, China chinaberry, larch, red pine, cedar, eucalyptus, walnut, magnolia, etc. can be used as the wood for the shaft 12. The specific gravity of the wood for the shaft 12 of this embodiment is 0.3 or more. In other words, domestic wood can be used as the wood for the shaft 12 of this embodiment. The shaft 12 may be made of solid wood or laminated wood. In addition to paraffin wax, materials that impart ease of cutting include glycerin fatty acid esters, urushi wax, Japan wax, microcrystalline wax, candelilla wax, montan wax, polyolefin wax, styrene-modified polyolefin wax, microcrystalline wax, polyethylene wax, carnauba wax, hazel wax, ethylene-vinyl acetate copolymer, ethylene-acrylic copolymer, silicone oil, liquid paraffin, spindle oil, squalane, α-olefin oligomer, Japan wax, beeswax, sucrose fatty acid esters, and dextrin fatty acid esters.

[0032] 1(A) to 1(E), the cross-sectional shape of shaft body 12 is hexagonal or circular. Note that in the present disclosure, the cross-sectional shape of shaft body 12 is not limited to a hexagonal or circular shape, and any geometric shape, such as an octagonal shape, can be adopted.

[0033] When the cross-sectional shape of the shaft body 12 is hexagonal as shown in Figures 1(A) to 1(C), the face-to-face distance W between the opposing outer surfaces of the hexagon is 7.4 mm or less, and the diameter RA of the circumscribing circle is 8 mm or less. Note that in the present disclosure, even if the cross-sectional shape of the shaft body is hexagonal, the face-to-face distance is not limited to 7.4 mm or less and the diameter of the circumscribing circle is not limited to 8 mm or less. In the present disclosure, the face-to-face distance and the diameter of the circumscribing circle can be set arbitrarily.

[0034] Furthermore, when the cross-sectional shape of the shaft body 12 is circular as shown in Figures 1(D) to 1(E), the diameter RB of the circle is 8 mm or less. Note that in the present disclosure, even if the cross-sectional shape of the shaft body is circular, the diameter of the circle is not limited to 8 mm or less. In the present disclosure, the diameter of the circle can be set arbitrarily. [Example]

[0035] (Example 1: Relationship between core diameter and allowable average cutting torque) Next, the relationship between the lead diameter and the allowable average value of cutting torque for the pencil 10 according to this embodiment will be explained using Examples 1 and 2. First, in Example 1, multiple pencils with different lead diameters were prepared, and the cutting torque of each pencil was measured. Specifically, three lead diameters, 2.05 mm, 2.6 mm, and 3.0 mm, were prepared, and multiple pencils for each lead diameter were prepared in a state that had never been cut after manufacturing. All pencil shafts were made of solid cypress wood. The lead hardness was 2B. The lead type was an ink lead.

[0036] Each pencil was then sharpened using a manual sharpener with a handle, while measuring the cutting torque. Each cutting was performed with the allowable average cutting torque varied between 7 cN·m and 14 cN·m. Note that the cutting torque can be measured using, for example, a known torque meter equipped with a magnetostrictive torque sensor.

[0037] In manual sharpeners with handles currently available on the market from several manufacturers, the blade member used to sharpen pencils has multiple grooved blades. The blade member also has a guide hole on the inside that supports the pencil lead inserted from the outside. When the handle is turned during sharpening, the blade member itself rotates, and the blade member rotates around the pencil, sharpening the supported lead and shaft inside.

[0038] The presence or absence of breakage of the lead after cutting was confirmed visually. Breakage was defined as a break formed in a portion of the lead located on the tip side of the boundary between the lead and the shaft on the cut surface. The results of Example 1 are shown in Table 1.

[0039] [Table 1]

[0040] A circle (○) in each column in Table 1 means that no breakage was confirmed in any of the pencils that were cut. Also, a cross (×) in each column in Table 1 means that breakage was confirmed in any of the pencils that were cut.

[0041] As can be seen from the row for the 2.05mm (Φ2.05) core diameter in Table 1, when the core diameter was 2.0mm, the allowable average value (in other words, the maximum value) of the cutting torque at which cutting could be performed without the core breaking was 8cN·m. Also, as can be seen from the row for the 2.6mm (Φ2.6) core diameter in Table 1, when the core diameter was 2.6mm, the allowable average value of the cutting torque at which cutting could be performed without the core breaking was 10cN·m. As can be seen from the row for the 3.0mm (Φ3.0) core diameter in Table 1, the allowable average value of the cutting torque at which cutting could be performed without the core breaking was 13cN·m or less.

[0042] When the same test as in Example 1 was conducted for lead hardness other than 2B, such as H, the same results were obtained. When the same test as in Example 1 was conducted for lead types other than ink, such as colored leads, the same results were obtained.

[0043] (Example 2: Torque measurement with a pocket sharpener) Next, Example 2 will be described, in which a portable pocket sharpener was used as the cutting tool instead of a manual sharpener with a handle. In Example 2, as in Example 1, the cutting torque of multiple pencils with different lead diameters was measured. In Example 2, the test conditions were the same as in Example 1, except that a portable pocket sharpener was used.

[0044] The pocket sharpener has a conical insertion hole and a straight blade fixed inside the insertion hole. Examples of the pocket sharpener that can be used include the manual pencil sharpener disclosed in JP 2015-083355 A and the pocket sharpener disclosed in JP 2010-82868 A.

[0045] Compared to a manual sharpener with a handle, with a pocket sharpener, the cutting resistance during cutting makes it easier for the shaft 12 to shift up and down and left and right relative to the fulcrum of the lead 14 inside the insertion hole, i.e., it is easier for bending and twisting to occur. Furthermore, bending and twisting can easily cause a relatively large load to be applied to the tip of the lead.

[0046] The wooden pieces of the shafts used in Example 2 and the allowable average cutting torque values ​​[cN·m] obtained for each wooden piece of the shaft are shown below. Camphor tree, ginkgo: 8 [cN·m] Hinoki: 8.5 [cN·m] Red pine: 9 [cN m] Cedar: 14 [cN·m]

[0047] (Action and effect) In the pencil 10 according to this embodiment, the diameter of the lead 14 is 3.0 mm or more, and therefore the cutting volume of the lead 14 generated when cutting the pencil 10 is larger than that of a pencil having the same dimensions and shape except that the diameter of the lead 14 is less than 3.0 mm. The increased cutting volume of the lead 14 reduces the cutting volume of the wood of the shaft 12 generated when cutting the pencil 10. Therefore, when the diameter of the lead 14 is 3.0 mm or more, the cutting resistance of the wood of the shaft 12 can be reduced, and as a result, the cutting torque can be reduced. This improves the surface quality of the pencil 10 after cutting.

[0048] In this embodiment, when the cross section of the shaft 12 is hexagonal, the inter-face distance W between the opposing outer surfaces of the hexagon is 7.4 mm or less, and the diameter RA of the circumscribed circle is 8 mm or less. When the cross section of the shaft 12 is circular, the diameter RB of the circle is 8 mm or less.

[0049] Here, the hexagonal shaft 12 is a shape that is commonly used for pencils 10, and dimensions in which the face-to-face distance W is 7.4 mm or less and the circumscribed circle diameter RA is 8 mm or less are also commonly used. In addition, the circular shaft 12 is a shape that is commonly used for pencils 10, and dimensions in which the circle diameter RB is 8 mm or less are also commonly used. This makes it possible to provide a wide range of pencils 10 with improved surface quality.

[0050] In this embodiment, the allowable average cutting torque at which cutting can be performed without breaking the lead 14 is 10 cN·m or less. Therefore, as in Example 2, even if a pencil sharpener that is prone to bending and twisting, such as a pocket sharpener, is used, it is easy to improve the surface quality of the pencil 10 after cutting.

[0051] <Other embodiments> Although the present disclosure has been described using the above disclosed embodiments, the descriptions and drawings that form part of this disclosure should not be understood as limiting the present disclosure. For example, in the present disclosure, an adhesive layer containing an epoxy resin or the like may be provided between the core and the shaft. The epoxy resin penetrates into the wood of the shaft. The adhesive layer can further prevent breakage of the core during cutting. Specifically, the adhesive layer can be formed using an adhesive such as PM100 disclosed in JP 2010-082868 A.

[0052] Furthermore, the present disclosure can be configured by partially combining the configurations exemplified in the multiple examples disclosed in the specification. The present disclosure includes various embodiments not described above, and the technical scope of the present disclosure is defined only by the invention-specifying matters in the claims that are appropriate from the above description. [Explanation of symbols]

[0053] 10,10A,10B Pencil 12,12A,12B Shaft 13 Hollow part 14,14B Core 16 Conductive core 18 Conductive contact portion 22 Diameter of fixing member RC core RA: Diameter of the circumscribed circle of the hexagonal shaft RB: Diameter of the circular shaft W: Distance between faces of hexagonal shaft

Claims

1. A core having a diameter of 3.0 mm or more; a shaft body covering the core and made of wood having an air-dry specific gravity of less than 0.6 and not containing a material that imparts easy cutting properties; A pencil.

2. The cross-sectional shape of the shaft is hexagonal or circular, When the cross-sectional shape of the shaft is hexagonal, the distance between the opposing outer surfaces of the hexagon is 7.4 mm or less, and the diameter of the circumscribed circle is 8 mm or less, When the cross-sectional shape of the shaft is circular, the diameter of the circle is 8 mm or less. The pencil of claim 1.

3. The allowable average value of the cutting torque at which cutting can be performed without breaking the core is 10 cN m or less.

3. The pencil according to claim 1 or 2.

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