Interdental cleaning tools

Abstract

The present invention provides an interdental cleaning tool that can effectively remove foreign matter from between teeth through an opening formed in the cleaning section. [Solution] The interdental cleaning tool 1 comprises a main body 2 including a base 4 and a shaft 5, and a cleaning part 3 including a cylindrical covering part 6 that covers the tip portion 50 of the shaft. At least two pairs of first recesses 52 and second recesses 53 are formed on the outer circumferential surface 55 of the tip portion 50, extending along the axial direction of the shaft 5 and arranged side by side in the circumferential direction of the shaft 5. Multiple openings 62 are formed in the covering part 6 that expose the tip portion 50, and the openings 62 are arranged to face a protrusion 54 located between the pair of first recesses 52 and second recesses 53 of the shaft 5. At the opening edge 63 of the covering part 6, the first end e1 in the lateral direction is located within the first recess 52, and at the opening edge 63, the second end e2 in the lateral direction is located within the second recess 53.

Description

Technical Field

[0001] The present disclosure relates to interdental cleaning tools.

Background Art

[0002] For example, referring to Patent Document 1, as an interdental cleaning tool for cleaning between teeth, it includes a main body portion including a base portion including a portion grasped by a user and a rod-shaped shaft portion connected to the base portion, and a soft cleaning portion attached to a shaft tip side portion which is a part of the tip side of the shaft portion. It is known that a user holds the base portion and inserts the cleaning portion between teeth, and by moving the cleaning portion between teeth, foreign substances such as food debris sandwiched between teeth and dental plaque adhering to teeth are scraped out from between teeth by the cleaning portion. Thus, the interdental cleaning tool can clean between teeth.

[0003] This type of interdental cleaning tool is manufactured through a first step of forming the main body portion and a second step of forming the cleaning portion. In the first step, the main body portion is formed by pouring a synthetic resin material such as polypropylene into a filling space formed inside a first mold having a shape corresponding to the main body portion. In the subsequent second step, using a second mold in which a filling space having a shape corresponding to the cleaning portion is formed around the shaft tip side portion while holding the main body portion inside, the cleaning portion is formed by filling the filling space with a polymer material having elasticity such as an elastomer while holding the main body portion inside the second mold.

[0004] In the second step, the shaft tip side portion is positioned at the center of the filling space in the second mold by being sandwiched by a pair of opposing holding pins in a direction orthogonal to the axial direction of the shaft portion. Thereby, when filling the filling space with material in the second step, it is suppressed that the shaft portion is bent or the like, and a cleaning portion having a uniform thickness in the circumferential direction can be formed.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2017-42493 [Overview of the project] [Problems that the invention aims to solve]

[0006] As described above, when forming the cleaning section in the second step, the shaft tip side portion is held by a pair of retaining pins. Therefore, in the covering portion that covers the shaft tip side portion in the cleaning section, openings are formed that penetrate in the thickness direction at positions corresponding to the retaining pins. As shown in Figure 14, for example, in the interdental cleaning tool 100 described in Patent Document 1, an opening 107 is formed in the covering portion 102 of the cleaning section 101 at a position opposite to a protrusion 106 located between the first recess 104 and the second recess 105 formed on the outer circumferential surface of the shaft portion 103.

[0007] In the cleaning section 101, the opening 107 is a part that can scrape off plaque and other debris attached to the teeth, but this point is not taken into consideration in Patent Document 1, so there is room for improvement.

[0008] In view of the above-mentioned problems, this disclosure aims to provide an interdental cleaning tool that can effectively remove foreign matter from between teeth through an opening formed in the cleaning section. [Means for solving the problem]

[0009] An interdental cleaning tool according to a first aspect of the present disclosure comprises a main body portion including a base portion including a portion to be grasped by a user and a shaft portion extending from the base and connected to the base, and a cleaning portion including a cylindrical covering portion that covers a part of the shaft tip portion, which is a part of the shaft tip portion, such that its inner surface contacts the outer surface of the shaft tip portion. In the interdental cleaning tool according to a first aspect of the present disclosure, at least two pairs of recesses are formed on the outer surface of the shaft tip portion, extending along the axial direction of the shaft portion and arranged side by side in the circumferential direction of the shaft portion. In addition, a plurality of openings are formed in the covering portion that expose the shaft tip portion. In addition, the openings are arranged to face a protrusion located between the pair of recesses of the shaft portion. In addition, in the covering portion, the first end, which is one end in the lateral direction of the opening edge portion that defines the opening, is located in the first recess of the pair of recesses, and the second end, which is the other end in the lateral direction of the opening edge portion, is located in the second recess of the pair of recesses.

[0010] As an interdental cleaning tool according to a second aspect of this disclosure, the interdental cleaning tool according to the first aspect described above may be configured such that the thickness of the covering portion at the first and second ends of the opening edge is 0.1 mm or more and 0.4 mm or less.

[0011] As an interdental cleaning tool according to a third aspect of this disclosure, the interdental cleaning tool according to the first or second aspect described above may be configured such that the first recess and the second recess are curved convexly toward the center of the shaft in a cross-section which is perpendicular to the axial direction of the shaft.

[0012] As an interdental cleaning tool according to the fourth aspect of the present disclosure, an interdental cleaning tool according to any one of the first to third aspects described above may be configured such that the convex portion is defined in the cross-section by a first concave curved surface that is concavely curved to define the first recess, a second concave curved surface that is concavely curved to define the second recess, and a convex curved surface that is convexly curved toward the opposite side of the center of the shaft portion and smoothly connects with the first concave curved surface and the second concave curved surface.

[0013] As an interdental cleaning tool according to the fifth aspect of this disclosure, the interdental cleaning tool according to the fourth aspect described above may be configured such that the angle of inclination of the line segment connecting the apex of the convex curved surface and the bottom of the first concave curved surface and the bottom of the second concave curved surface with respect to the direction parallel to the width direction of the opening is 15° or more and 65° or less.

[0014] As an interdental cleaning tool according to the sixth aspect of this disclosure, an interdental cleaning tool according to any one of the first to fifth aspects described above may be configured such that the cleaning portion further includes a plurality of protrusions that protrude from the outer circumferential surface of the covering portion. [Effects of the Invention]

[0015] According to the interdental cleaning device described herein, foreign matter can be effectively scraped out from between the teeth by the opening formed in the cleaning portion. [Brief explanation of the drawing]

[0016] [Figure 1] Figure 1 is a front view of an interdental cleaning tool according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a side view of an interdental cleaning tool according to one embodiment of the present disclosure. [Figure 3] Figure 3 is an enlarged front view showing a portion of an interdental cleaning tool according to one embodiment of the present disclosure. [Figure 4] Figure 4 is a cross-sectional view of an interdental cleaning tool according to one embodiment of the present disclosure, when cut along a vertical plane including the line I-I shown in Figure 1. [Figure 5A] Figure 5A is a cross-sectional end view of an interdental cleaning tool according to one embodiment of the present disclosure, when cut along a horizontal plane including the line II-II shown in Figure 1. [Figure 5B] Figure 5B is a cross-sectional end view of an interdental cleaning tool according to one embodiment of the present disclosure, when cut along a horizontal plane including the line III-III shown in Figure 1. [Figure 6] Figure 6 is a front view showing an enlarged portion of the tip of the shaft. [Figure 7]FIG. 7 is a side view showing an enlarged part of the tip side of the shaft portion. [Figure 8A] FIG. 8A is a cross-sectional view of a part of the tip side of the shaft portion. [Figure 8B] FIG. 8B is a cross-sectional view showing an enlarged part of FIG. 8A. [Figure 9] FIG. 9 is a perspective view of the cleaning portion. [Figure 10] FIG. 10 is a plan view of the cleaning portion. [Figure 11A] FIG. 11A is a diagram for explaining a step of a method for manufacturing an interdental cleaner according to an embodiment of the present disclosure. [Figure 11B] FIG. 11B is a diagram for explaining a step of a method for manufacturing an interdental cleaner according to an embodiment of the present disclosure. [Figure 11C] FIG. 11C is a diagram for explaining a step of a method for manufacturing an interdental cleaner according to an embodiment of the present disclosure. [Figure 12] FIG. 12 is a diagram for explaining problems that may occur in a method for manufacturing an interdental cleaner according to the prior art. [Figure 13] FIG. 13 is a diagram for explaining the effects achieved in a method for manufacturing an interdental cleaner according to an embodiment of the present disclosure. [Figure 14] FIG. 14 is an end view of a cut portion when the shaft portion of an interdental cleaner according to the prior art is cut with a plane perpendicular to the axial direction.

DETAILED DESCRIPTION OF THE INVENTION

[0017] Specific embodiments of the interdental cleaner according to the present disclosure will be described with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

[0018] <Overview of the interdental cleaner> Figure 1 is a front view of an interdental cleaning tool 1 according to one embodiment of the present disclosure. Figure 2 is a side view of an interdental cleaning tool 1 according to one embodiment of the present disclosure. Figure 3 is an enlarged front view showing a portion of the interdental cleaning tool 1 according to one embodiment of the present disclosure. Figure 4 is a cross-sectional view of the interdental cleaning tool 1 according to one embodiment of the present disclosure along the line X-X shown in Figure 1. Figure 5A is an end view of the interdental cleaning tool 1 according to one embodiment of the present disclosure along the line Y-Y shown in Figure 1. Figure 5B is an end view of the interdental cleaning tool 1 according to one embodiment of the present disclosure along the line Z-Z shown in Figure 1.

[0019] Referring to Figures 1 to 5, the interdental cleaning tool 1 comprises a main body 2 and a cleaning part 3. The main body 2 includes a base 4 and a shaft 5. The base 4 and the shaft 5 are integrally formed. The shaft 5 is connected to the base 4 so as to extend from it. The cleaning part 3 includes a covering part 6 and a plurality of protrusions 7. The covering part 6 and the plurality of protrusions 7 are integrally formed. The covering part 6 is attached to the shaft 5 so as to cover the shaft tip portion 50, which is a part of the shaft 5 that is on the tip side. The plurality of protrusions 7 protrude from the outer circumferential surface of the covering part 6.

[0020] The cleaning section 3 is made of a softer material with lower hardness than the main body section 2. The cleaning section 3 is inserted between the user's teeth when using the interdental cleaning tool 1, and the interdental spaces are cleaned by the cleaning section 3. When cleaning with the cleaning section 3, the multiple protrusions 7 function as brushes. In the main body section 2, the base section 4 is the part that is held by the user when using the interdental cleaning tool 1. In the main body section 2, the shaft section 5 is the part that provides the covering section 6 with appropriate hardness so that it does not bend unnecessarily when the cleaning section 3 is inserted between the teeth when using the interdental cleaning tool 1.

[0021] The following describes in detail each component constituting the interdental cleaning tool 1. In this disclosure, the direction in which the shaft portion 5 extends is referred to as the axial direction. The side of the shaft portion 5 to which the cleaning portion 3 is attached is referred to as the tip side, and the side opposite the tip side to which the base portion 4 is provided is referred to as the base end side. The direction surrounding the shaft portion 5 in a plane perpendicular to the axial direction is referred to as the circumferential direction.

[0022] <Description of the main unit> Referring to Figures 1 and 2, the main body 2 is formed from, for example, a synthetic resin material. Examples of synthetic resin materials include polypropylene, polyethylene, acrylonitrile-butadiene-styrene copolymer (ABS), polybutylene terephthalate, polyethylene terephthalate, polycarbonate, polystyrene, polyacetal, and polyamide. The main body 2 may also be formed from a synthetic resin material to which fibrous materials such as glass fibers and carbon fibers are added. For example, glass fibers are added to the synthetic resin material in a proportion of 15% to 35% by mass.

[0023] The main body 2 is formed, for example, by injection molding, as will be described in detail later, and thereby the base 4 and the shaft 5 are integrated.

[0024] <Explanation of the base> Referring to Figures 1 and 2, the base 4 is formed to include, for example, a gripping portion 40 and a connecting portion 41. The gripping portion 40 and the connecting portion 41 are integrally formed. In the base 4, the gripping portion 40 is the part that is gripped by the user. The gripping portion 40 is, for example, a thin, flat plate shape and has a pair of main surfaces spaced apart in the thickness direction. The shape of the gripping portion 40 when viewed from a direction perpendicular to the main surfaces (the shape of the gripping portion 40 when viewed from the front) is, for example, rectangular. The gripping portion 40 can be formed into various shapes as long as it can be gripped by the user, and the shape of the gripping portion 40 is not particularly limited.

[0025] In the base 4, the connecting portion 41 is the part that connects the plate-shaped gripping portion 40 and the rod-shaped shaft portion 5. The connecting portion 41 is formed such that, for example, its width gradually narrows from the base end on the side connected to the gripping portion 40 to the tip on the side connected to the shaft portion 5. The shape of the connecting portion 41 when viewed from a direction perpendicular to the main surface of the gripping portion 40 is, for example, triangular. As a result, the shape of the connecting portion 41 transitions from a plate-like shape with a rectangular cross-section at the first end to a rod-like shape with a square cross-section at the second end, and the gripping portion 40 and the shaft portion 5 are connected by the connecting portion 41.

[0026] <Explanation of the shaft> Figure 6 is a front view showing an enlarged view of the shaft tip portion 50, which is a part of the shaft portion 5 towards the tip. Figure 7 is a side view showing an enlarged view of the shaft tip portion 50. Figure 8A is a cross-sectional view of the shaft tip portion. Figure 8B is a cross-sectional view showing an enlarged view of a part of Figure 8A.

[0027] Referring to Figures 1, 2, 4, and 6 through 8A, the shaft portion 5 is, for example, rod-shaped. The cross-sectional shape of the shaft portion 5, which is perpendicular to the axial direction, is, for example, circular. The shaft portion 5 is formed in a tapered shape, for example, with the diameter decreasing from the base end on the connecting portion 41 side to the tip on the cleaning portion 3 side. The length of the shaft portion 5 is not particularly limited, but is, for example, 15 mm or more and 25 mm or less.

[0028] The shaft portion 5 includes a shaft tip portion 50 which extends for a predetermined length from the tip. The shaft portion 5 also includes a shaft base portion 51 which is a part of the shaft portion 5 on the base end side and is located between the shaft tip portion 50 and the base portion 4. The diameter of the shaft portion 5 is not particularly limited, but is, for example, 0.3 mm or more and 0.7 mm or less in the shaft tip portion 50, and for example, 0.9 mm or more and 1.3 mm or less in the shaft base portion 51.

[0029] A pair of recesses, a first recess 52 and a second recess 53, are formed on the outer circumferential surface 55 of the shaft tip portion 50. The first recess 52 and the second recess 53 extend from near the tip of the shaft portion 5 along the axial direction of the shaft portion 5. The first recess 52 and the second recess 53 are also arranged side by side in the circumferential direction of the shaft portion 5. In this embodiment, the first recess 52 and the second recess 53 are arranged with a gap between them in the circumferential direction of the shaft portion 5.

[0030] The first recess 52 and the second recess 53 are formed by a portion of the outer circumferential surface 55 being recessed inward in the shaft tip portion 50. Referring to Figures 8A and 8B, the first recess 52 and the second recess 53 are formed, for example, in the cross-section of the shaft tip portion 50, by a portion of the outer circumferential surface 55 being curved convexly toward the center C of the shaft portion 5. The first recess 52 and the second recess 53 are formed symmetrically with respect to the first plane P1 as the plane of symmetry. The first plane P1 is a virtual plane that includes the center C of the shaft portion 5, is perpendicular to the cross-section, and passes between the first recess 52 and the second recess 53.

[0031] Referring to Figures 8A and 8B, in the shaft tip portion 50, between the pair of first recesses 52 and second recesses 53, there is a protrusion 54 that projects toward the opposite side of the center C of the shaft portion 5. The protrusion 54 is defined, for example, by a first concave curved surface 56 that defines the first recess 52, a convex curved surface 57A that curves toward the opposite side of the center C of the shaft portion 5, and a second concave curved surface 58 that defines the second recess 53. The convex curved surface 57A is a part of the circular virtual circumferential surface F that forms the outer circumferential surface of the shaft tip portion 50 when the cross-section of the shaft tip portion 50 is circular, and is smoothly connected to the first concave curved surface 56 and the second concave curved surface 58.

[0032] Referring to Figure 8B, in the cross-section of the shaft tip portion 50, let θ be the angle (angle of inclination) of the virtual plane L1 connecting the apex A of the convex surface 57A between the first concave surface 56 and the second concave surface 58, and the bottom B of the first concave surface 56 and the bottom B of the second concave surface 58, with respect to the direction in which the virtual plane L2 connecting the bottom B of the first concave surface 56 and the second concave surface 58 extends. Here, the apex A of the convex surface 57A is the part of the convex surface 57A that intersects with the first plane P1 and is the part furthest from the second plane P2. The second plane P2 is a virtual plane that includes the center C of the shaft portion 5 and is perpendicular to the cross-section and the first plane P1. Furthermore, the bottom B of the first concave surface 56 and the bottom B of the second concave surface 58 are the parts that are radially furthest from the circular virtual circumferential surface F of the shaft tip side portion 50 when the cross-section of the shaft tip side portion 50 is circular. The line segment connecting the bottom B of the first concave surface 56 and the second concave surface 58 is parallel to the width direction of the opening 62, which will be described later.

[0033] The inclination angle θ mentioned above is not particularly limited, but is preferably between 15° and 65°, and more preferably between 20° and 60°. The reason why an inclination angle θ of 15° or more and 65° or less is preferable will be explained later.

[0034] Although not shown in the illustration, the pair of first recesses 52 and second recesses 53 may be arranged side by side without spacing in the circumferential direction of the shaft portion 5, such that the end E1 of the first recess 52 closest to the second recess 53 and the end E2 of the second recess 53 closest to the first recess 52 coincide in the circumferential direction of the shaft portion 5. In this case, the convex portion 54 is defined by a first concave curved surface 56 that defines the first recess 52 and a second concave curved surface 58 that defines the second recess 53.

[0035] Referring to Figure 8A, at least two pairs of first recesses 52 and second recesses 53 are formed on the outer circumferential surface 55 of the shaft tip portion 50. In this embodiment, two pairs of first recesses 52 and second recesses 53 are formed on the outer circumferential surface 55 of the shaft tip portion 50. That is, two first recesses 52 and two second recesses 53 are formed on the outer circumferential surface 55 of the shaft tip portion 50. The two first recesses 52 are located on one side of the second plane P2, and the two second recesses 53 are located on the other side of the second plane P2. The first pair of first recesses 52 and second recesses 53 and the second pair of first recesses 52 and second recesses 53 are arranged symmetrically with respect to the second plane P2.

[0036] Referring to Figures 8A and 8B, a pair of flat surfaces 59 may be formed on the outer circumferential surface 55 of the shaft tip portion 50. One flat surface 59 is formed between two first recesses 52, and the other flat surface 59 is formed between two second recesses 53. Between one flat surface 59 and the two first recesses 52, and between the other flat surface 59 and the two second recesses 53, a convex curved surface 57B, which is a part of the circular virtual circumferential surface F that is the outer circumferential surface of the shaft tip portion 50, which has a circular cross-section, is interposed.

[0037] <Explanation from the Cleaning Department> Figure 9 is a perspective view of the cleaning unit 3. Figure 10 is a plan view of the cleaning unit 3.

[0038] Referring to Figures 9 to 10, the cleaning section 3 is formed from an elastic polymer material. The cleaning section 3 is formed from, for example, an elastomer material. Examples of elastomer materials include styrene-based elastomers, silicone, olefin-based elastomers, and polyester-based elastomers.

[0039] The cleaning section 3, as will be described in detail later, is formed, for example, by injection molding, so that the covering section 6 and the multiple protrusions 7 are integrated together.

[0040] <Explanation of the covering part> Referring to Figures 1 to 5B and Figures 9 to 10, the covering portion 6 is cylindrical. The cross-sectional shape of the covering portion 6, which is perpendicular to the axial direction of the shaft portion 5, is, for example, circular on the outer circumference and matches the outer shape of the shaft tip portion 50 on the inner circumference. As a result, the covering portion 6 covers the shaft tip portion 50 such that the inner surface 60 contacts the outer surface 55 of the shaft tip portion 50. In the covering portion 6, the tip, which is the end on the same side as the tip of the shaft portion 5, is closed, while the base end, which is the end on the same side as the base end of the shaft portion 5, is open, exposing the shaft base end portion 51. The covering portion 6 is formed in a tapered shape, for example, similar to the shaft portion 5, with the diameter decreasing from the base end to the tip. This makes it easier for the cleaning portion 3 to be inserted between the user's teeth together with the shaft portion 5.

[0041] The length of the covering portion 6 (distance from the base end to the tip) is not particularly limited, but is, for example, 13 mm or more and 18 mm or less. The thickness of the covering portion 6 is, for example, 0.1 mm or more and 0.28 mm or less.

[0042] The covering portion 6 has multiple openings 62 that expose the shaft tip portion 50. The openings 62 are through holes that penetrate the peripheral wall of the covering portion 6 in the thickness direction. As will be described in detail later, these openings 62 are formed in the covering portion 6 when the shaft tip portion 50 is held in place by a pair of retaining pins during the injection molding of the cleaning portion 3.

[0043] The shape of the opening 62 when viewed from the front can be a circle, oval, ellipse, square, rectangle, rhombus, or regular polygon, and in this embodiment it is a vertically elongated ellipse that is long in the axial direction of the shaft portion 5.

[0044] The openings 62 are positioned to face a protrusion 54 located between a pair of first recesses 52 and second recesses 53 on the shaft portion 5. Multiple openings 62 (three in this embodiment) are positioned at intervals along the axial direction of the shaft portion 5 relative to the first pair of first recesses 52 and second recesses 53 on the shaft portion 5. Multiple openings 62 (three in this embodiment) are also positioned at intervals along the axial direction of the shaft portion 5 relative to the second pair of first recesses 52 and second recesses 53 on the shaft portion 5. In other words, a first group of multiple openings 62 arranged in a line along the axial direction of the shaft portion 5 and a second group of multiple openings 62 arranged in a line along the axial direction of the shaft portion 5 are positioned to face each other with the shaft portion 5 in between.

[0045] In each group, the spacing between the openings 62 along the axial direction of the shaft portion 5 may all be the same, or may differ in some or all respects. The openings 62 facing each other between the first group and the second group may completely overlap without vertical displacement, or they may be vertically offset and partially overlap, or they may not overlap at all. In this embodiment, the top two openings 62 of the first group and the top two openings 62 of the second group face each other without vertical displacement. On the other hand, the lowest opening 62 of the first group and the lowest opening 62 of the second group face each other with vertical displacement.

[0046] Referring to Figure 5A, the width of the opening 62 is greater than the distance between the pair of first recesses 52 and second recesses 53 in the shaft portion 5. Here, the width of the opening 62 refers to the maximum length in the opening 62 that is perpendicular to the axial direction of the shaft portion 5 and the thickness direction of the covering portion 6 (the width direction). For example, if the shape of the opening 62 when viewed from the front is circular, the width of the opening 62 refers to the diameter, and if it is a vertically elongated ellipse, the width of the opening 62 refers to the length of the minor axis. Also, the distance between the pair of first recesses 52 and second recesses 53 refers to the distance between the end E1 of the first recess 52 and the end E2 of the second recess 53 in the circumferential direction of the shaft portion 5. Note that if the pair of first recesses 52 and second recesses 53 are arranged side by side without any gap in the circumferential direction of the shaft portion 5, the distance between the pair of first recesses 52 and second recesses 53 is zero.

[0047] As a result, in the opening edge 63 that defines the opening 62 in the covering portion 6, the first end e1, which is one end in the lateral direction, is located within the first recess 52 of the pair of first and second recesses 52 of the shaft portion 5. Also, the second end e2, which is the other end in the lateral direction of the opening edge 63, is located within the second recess 53 of the pair of first and second recesses 52 of the shaft portion 5. Here, the first end e1 and the second end e2 of the opening edge 63 are the two ends that define the lateral width of the opening 62, and are the two ends that are furthest apart in the lateral direction of the opening edge 63.

[0048] Thus, the first end e1 and the second end e2 of the opening edge 63 of the covering portion 6 are located within the first recess 52 and the second recess 53 of the shaft tip side portion 50, respectively. As a result, the first end e1 and the second end e2 of the opening edge 63 protrude outward from the first concave curved surface 56 and the second concave curved surface 58, respectively, on the outer circumferential surface 55 of the shaft tip side portion 50, which are recessed inward from the circular circumferential surface of the shaft tip side portion 50 when the cross-section of the shaft tip side portion 50 is circular. Therefore, compared to the case where the first end e1 and the second end e2 of the opening edge 63 are located within the convex portion 54 of the shaft tip side portion 50 and protrude outward from the circular circumferential surface, i.e., the convex curved surface 57A, the thickness of the covering portion 6 at the first end e1 and the second end e2 of the opening edge 63 is larger.

[0049] When the cleaning part 3 is inserted between teeth, the covering part 6's outer surface 61 rubs against the teeth, scraping off foreign matter such as plaque attached to the teeth, and the opening edge 63 also rubs against the teeth, scraping off foreign matter. The greater the thickness of the covering part 6 at the first end e1 and the second end e2 of the opening edge 63, the more easily the opening edge 63 flexes, and thus the greater the force with which the opening edge 63 can scrape off foreign matter. Therefore, the opening edge 63 can effectively scrape out foreign matter from between teeth.

[0050] Furthermore, since the first end e1 and second end e2 of the opening edge 63 in the covering portion 6 are located within the first recess 52 and the second recess 53 of the shaft tip side portion 50, respectively, foreign matter scraped off by the opening edge 63 accumulates in the first recess 52 and the second recess 53. As a result, more foreign matter can be scraped off by the opening edge 63, and thus foreign matter can be effectively scraped out from between the teeth.

[0051] The thickness of the covering portion 6 at the first end e1 and second end e2 of the opening edge portion 63 is not particularly limited, but is preferably 0.1 mm or more and 0.4 mm or less, and more preferably 0.18 mm or more and 0.25 mm or less. A thickness of 0.1 mm or more, preferably 0.18 mm or more, allows the opening edge portion 63 to more effectively scrape off foreign matter. A thickness of 0.4 mm or less, preferably 0.25 mm or less, prevents the covering portion 6 from becoming too thick, making it easier to insert the cleaning portion 3 between teeth.

[0052] <Explanation of the protrusions> Referring to Figures 1 to 5B and Figures 9 to 10, the multiple protrusions 7 extend from the outer circumferential surface 61 of the covering portion 6. The multiple protrusions 7 are scattered along the entire circumference of the shaft portion 5, from the tip to the base of the covering portion 6. For example, the multiple protrusions 7 are arranged in a single spiral along the circumference of the shaft portion 5, from the tip to the base of the covering portion 6.

[0053] The multiple projections 7 are elongated and rod-shaped. The multiple projections 7 may be formed in a tapered shape, for example, conical, such that their diameter gradually decreases as they move away from the outer circumferential surface 61 of the covering portion 6. The thickness of the multiple projections 7 may be uniform or non-uniform. The multiple projections 7 may be formed such that, for example, the diameter at the base of the projection 7 gradually decreases as you move from the base end to the tip of the covering portion 6. The diameter at the base of the projection 7 is not particularly limited, but is for example 0.25 mm to 0.60 mm. The length of the multiple projections 7 protruding from the covering portion 6 (hereinafter referred to as "height") may be uniform or non-uniform. The multiple projections 7 may be formed such that, for example, the height of the projection 7 gradually decreases as you move from the base end to the tip of the covering portion 6. The height of the projection 7 is not particularly limited, but is for example 0.5 mm to 1.7 mm.

[0054] <Explanation of the manufacturing method for interdental cleaning tools> Next, the manufacturing method of the interdental cleaning tool 1 will be described. The manufacturing method of the interdental cleaning tool 1 includes a first step of forming the main body 2 and a second step of forming the cleaning part 3.

[0055] In the first step, a first mold is prepared, which has a filling space formed inside that has a shape corresponding to the main body 2 (though this is not shown in the diagram). The first mold is separable into a first part and a second part. Next, a synthetic resin material such as polypropylene is poured into the filling space in the first mold. This forms the main body 2, which includes the base 4 and the shaft 5. After that, the main body 2 is removed from the first mold by separating the first mold into a first part and a second part.

[0056] Next, in the second step, first, referring to Figure 11A, a second mold 8 is prepared for forming the cleaning unit 3 to be attached to the shaft 5 of the main body 2. The second mold 8 is separable into a first part 81 and a second part 82. The second mold 8 can accommodate the main body 2 and can hold the shaft base end portion 51 of the shaft 5, etc. The second mold 8 also has a shape in which a filling space 80 is formed around the shaft tip portion 50 of the shaft 5, which has a shape corresponding to the cleaning unit 3. In addition, the first part 81 and the second part 82 of the second mold 8 are integrally provided with a plurality of retaining pins 9 such that their tips protrude into the filling space 80.

[0057] Next, after the main body 2 is set between the separated first part 81 and second part 82, the first part 81 and second part 82 are joined together, as shown in Figure 11B, and the shaft tip portion 50 is held in place by multiple retaining pins 9. Then, as shown in Figure 11C, for example, an elastomer material is poured from the ket into the filling space 80 in the second mold 8. This forms a cleaning part 3 including a covering part 6 and multiple protrusions 7, and the cleaning part 3 is attached to the shaft 5 such that the shaft tip portion 50 is covered by the covering part 6. In this way, the interdental cleaning tool 1 is manufactured. After that, the interdental cleaning tool 1 is removed from the second mold 8 by separating the second mold 8 into the first part 81 and second part 82.

[0058] Referring to Figure 11A, the retaining pin 9 that clamps the shaft tip portion 50 in the second step has a recess 90 formed on its tip surface 94 that fits with the protrusion 54 of the shaft tip portion 50. The recess 90 of the retaining pin 9 is defined by a concave curved surface 91 that abuts against the convex curved surface 57A of the protrusion 54 of the shaft tip portion 50, and a pair of convex curved surfaces, a first convex curved surface 92 and a second convex curved surface 93, which are convex curved surfaces with the concave curved surface 91 in between. The first convex curved surface 92 abuts against a portion of the first concave curved surface 56 of the protrusion 54 of the shaft tip portion 50. The second convex curved surface 93 abuts against a portion of the second concave curved surface 58 of the protrusion 54 of the shaft tip portion 50. The first convex curved surface 92 and the second convex curved surface 93 are smoothly connected to the concave curved surface 91.

[0059] Referring to Figure 11B, the recesses 90 of the multiple retaining pins 9 engage with the protrusions 54 of the shaft tip portion 50, thereby clamping the shaft tip portion 50 with the multiple retaining pins 9 and positioning the shaft tip portion 50 in the center of the filling space 80 in the second mold 8. This suppresses bending of the shaft tip portion 50 when, for example, elastomer material is filled into the filling space 80 in the second mold 8 during the second step, and a covering portion 6 with uniform thickness in the circumferential direction is formed.

[0060] In the second step described above, if the tip surface 94 defining the recess 90 of the retaining pin 9 has a first convex curved surface 92 and a second convex curved surface 93 on both sides of the concave curved surface 91, the following effects are achieved when fitting the recess 90 of the retaining pin 9 with the convex portion 54 of the shaft tip side portion 50.

[0061] Referring to Figure 12, for example, if the tip surface 94 of the retaining pin 9 has only a concave curved surface 91 and does not have convex curved surfaces 92 and 93 on both sides, when fitting the recess 90 of the retaining pin 9 with the convex portion 54 of the shaft tip side portion 50, if the convex portion 54 is misaligned laterally with respect to the recess 90, the tip surface 94 of the retaining pin 9 may pierce the convex portion 54 of the shaft tip side portion 50 at both pointed ends of the concave curved surface 91. In this case, the convex portion 54 of the shaft tip side portion 50 will not fit into the recess 90 of the retaining pin 9, and the recess 90 of the retaining pin 9 and the convex portion 54 of the shaft tip side portion 50 will not fit together. As a result, there are cases in which the shaft tip side portion 50 cannot be properly positioned with respect to the filling space in the second mold. Note that in Figure 12, only the retaining pin 9 of the second mold is shown, and the first and second parts that move together with the retaining pin 9 are not shown.

[0062] In contrast, referring to Figure 13, if the tip surface 94 of the retaining pin 9 has a first convex curved surface 92 and a second convex curved surface 93 on both sides of the concave curved surface 91, even if the convex portion 54 is misaligned laterally with respect to the concave surface 90 when fitting the concave portion 90 of the retaining pin 9 with the convex portion 54 of the shaft tip side portion 50, the tip surface 94 of the retaining pin 9 is less likely to pierce the convex portion 54 of the shaft tip side portion 50 because both ends of the tip surface 94 of the retaining pin 9 are convex curved surfaces 92 and 93. Then, the convex portion 54 of the shaft tip side portion 50 slides along the concave curved surface 91 of the tip surface 94 of the retaining pin 9 and fits into the concave surface 90, thus fitting the concave portion 90 of the retaining pin 9 with the convex portion 54 of the shaft tip side portion 50. Therefore, the shaft tip side portion 50 can be appropriately positioned with respect to the filling space in the second mold. In Figure 13, only the retaining pin 9 of the second mold is shown, and the first and second parts, which move integrally with the retaining pin 9, are omitted from the illustration.

[0063] Furthermore, if the inclination angle θ of the convex portion 54 from the top A to the bottom B on the outer circumferential surface 55 of the shaft tip portion 50 is 15° or more and 65° or less, preferably 20° or more and 60° or less, the convex portion 54 of the shaft tip portion 50 can easily slide on the concave curved surface 91 of the tip surface 94 of the retaining pin 9. Therefore, the convex portion 54 of the shaft tip portion 50 fits smoothly into the recess 90 of the retaining pin 9, making it easier for the recess 90 of the retaining pin 9 and the convex portion 54 of the shaft tip portion 50 to engage.

[0064] <Mechanism and effects of interdental cleaning tools> In the interdental cleaning tool 1 of this embodiment, referring to Figure 5A, the opening 62 of the covering portion 6 faces a protrusion 54 located between a pair of first recesses 52 and second recesses 53 of the shaft tip portion 50, the first end e1 in the lateral direction of the opening edge portion 63 defining the opening 62 is located within the first recess 52 of the shaft tip portion 50, and the second end e2 in the lateral direction of the opening edge portion 63 is located within the second recess 53 of the shaft tip portion 50. As a result, the thickness of the covering portion 6 at the first end e1 and second end e2 of the opening edge portion 63 can be increased, thereby increasing the force with which the opening edge portion 63 scrapes off foreign matter attached to the teeth when the cleaning portion 3 is inserted between teeth. Therefore, according to the interdental cleaning tool 1 of this embodiment, foreign matter can be effectively scraped out from between teeth by the opening edge portion 63.

[0065] Furthermore, since the foreign matter scraped off by the opening edge 63 accumulates in the first recess 52 and the second recess 53, the opening edge 63 can scrape off more foreign matter. Therefore, according to the interdental cleaning tool 1 of this embodiment, foreign matter can be effectively scraped out from between the teeth by the opening edge 63.

[0066] In addition, in the interdental cleaning tool 1 of this embodiment, the first recess 52 and the second recess 53 of the shaft tip portion 50 are curved convexly toward the center C of the shaft portion 5 in the cross-section of the shaft portion 5. Referring to Figure 5A, the first recess 52 is defined by a concave first curved surface 56, and the second recess 53 is defined by a concave second curved surface 58. The shape of the recess 90 of the retaining pin 9 used when manufacturing such an interdental cleaning tool 1 corresponds to the shape of the opening 62 of the covering portion 6, and the tip surface 94 defining the recess 90 of the retaining pin 9 has a first convex curved surface 92 and a second convex curved surface 93 on both sides, corresponding to the first concave curved surface 56 and the second concave curved surface 58, referring to Figure 11A, and both ends are not pointed. Therefore, referring to Figure 13, when fitting the recess 90 of the retaining pin 9 with the protrusion 54 of the shaft tip portion 50 during manufacturing, even if the protrusion 54 is misaligned laterally with respect to the recess 90, the tip surface 94 of the retaining pin 9 will not pierce the protrusion 54 of the shaft tip portion 50, but rather the protrusion 54 of the shaft tip portion 50 will slide along the concave curved surface 91 of the tip surface 94 of the retaining pin 9 and fit into the recess 90. Thus, with the interdental cleaning tool 1 of this embodiment, the recess 90 of the retaining pin 9 and the protrusion 54 of the shaft tip portion 50 can be fitted with high precision, allowing for efficient manufacturing of the interdental cleaning tool 1.

[0067] In addition, in the interdental cleaning tool 1 of this embodiment, as shown in Figure 5A, the protrusion 54 located between the first recess 52 and the second recess 53 of the shaft tip portion 50 has a convex curved surface 57A that smoothly connects with the first concave curved surface 56 and the second concave curved surface 58. As a result, as shown in Figure 13, when fitting the recess 90 of the retaining pin 9 and the protrusion 54 of the shaft tip portion 50 during manufacturing, if the protrusion 54 is misaligned laterally with respect to the recess 90, the protrusion 54 of the shaft tip portion 50 slides smoothly along the concave curved surface 91 of the tip surface 94 of the retaining pin 9 and fits into the recess 90. Therefore, with the interdental cleaning tool 1 of this embodiment, the recess 90 of the retaining pin 9 and the protrusion 54 of the shaft tip portion 50 can be fitted with high precision, allowing for efficient manufacturing of the interdental cleaning tool 1.

[0068] In addition, in the interdental cleaning tool 1 of this embodiment, the cleaning part 3 further includes a plurality of protrusions 7 that extend from the outer peripheral surface 61 of the covering part 6. When the cleaning part 3 is inserted between the user's teeth during use of the interdental cleaning tool 1, the plurality of protrusions 7 function as brushes. Therefore, the interdental cleaning tool 1 of this embodiment can improve the cleaning power of the cleaning part 3.

[0069] <Explanation of variations> Although an interdental cleaning tool 1 according to one embodiment of this disclosure has been described, the interdental cleaning tool 1 according to the above embodiment can be modified in various ways without departing from the spirit of this disclosure, for example, the following modifications are possible. The interdental cleaning tools of the following modified examples can solve the problems described in this disclosure in the same way as the interdental cleaning tool 1 according to the above embodiment. The interdental cleaning tool 1 according to the above embodiment can be applied by appropriately combining the modified examples shown below.

[0070] In the embodiment described above, the shaft portion 5 is formed in a straight line. In one modified interdental cleaning tool, for example, the shaft base end portion 51 of the shaft portion 5 may be curved in an arc shape. In this case, the axial direction of the shaft portion 5 refers to the direction in which the shaft tip end portion 50 extends.

[0071] In the embodiment described above, the base 4 is formed to include a gripping portion 40 and a connecting portion 41. In one modified interdental cleaning tool, the base 4 may be formed to include only the gripping portion 40 without the connecting portion 41, or a shaft portion 5 may be connected to the gripping portion 40. In this modified example, the gripping portion 40 can be formed into various shapes as long as the user can grip it, and the shape of the gripping portion 40 is not particularly limited.

[0072] In the embodiment described above, the cleaning section 3 is formed to include a covering section 6 and a plurality of protrusions 7. The cleaning section 3 only needs to include the covering section 6 and be shaped to scrape out foreign matter between teeth, and may not include the plurality of protrusions 7, or may be shaped to include a portion that can scrape out foreign matter in place of the plurality of protrusions 7.

[0073] The embodiments and modifications disclosed herein are illustrative in all respects and should be understood not to be restrictive in any way. The scope of the invention is defined by the claims rather than the foregoing description and is intended to include all modifications in the sense and scope equivalent to the claims. [Explanation of symbols]

[0074] 1: Interdental cleaning tool, 2: Main body, 3: Cleaning part, 4: Base, 5: Shaft, 6: Covering part, 7: Projection, 8: Second mold, 9: Retaining pin, 40: Gripping part, 41: Connecting part, 50: Shaft tip side part, 51: Shaft base end side part, 52: First recess, 53: Second recess, 54: Convex part, 55: Outer surface of shaft tip side part, 56: First concave curved surface, 57A: Convex curved surface, 57B: Convex curved surface, 58: Second concave curved surface, 59: Flat surface, 60: Covering 61: Inner circumferential surface of part, 62: Outer circumferential surface of covering part, 63: Opening edge, 80: Filling space, 81: First part, 82: Second part, 90: Recess, 91: Concave curved surface, 92: First convex curved surface, 93: Second convex curved surface, 94: Tip surface of retaining pin, A: Top, B: Bottom, C: Center, E1: End, E2: End, L1: Virtual plane, L: Virtual plane, P1: First plane, P2: Second plane, e1: First end, e2: Second end, θ: Inclination angle

Claims

1. A main body portion including a base portion that includes a part that is grasped by the user, and a shaft portion that is connected to the base portion and extends from the base portion, A cleaning unit including a cylindrical covering portion that covers the tip portion of the shaft, which is a part of the tip end of the shaft, such that its inner surface contacts the outer surface of the tip portion of the shaft, Equipped with, At least two sets of recesses are formed on the outer circumferential surface of the tip portion of the shaft, extending along the axial direction of the shaft and arranged side by side in the circumferential direction of the shaft. The covering portion has multiple openings that expose the shaft tip side portion. The opening is positioned to face the protrusion located between the pair of recesses of the shaft portion, An interdental cleaning tool in which, in the covering portion, the first end, which is one end in the lateral direction of the opening edge that defines the opening, is located in the first recess of the pair of recesses, and the second end, which is the other end in the lateral direction of the opening edge, is located in the second recess of the pair of recesses.

2. The interdental cleaning tool according to claim 1, wherein the thickness of the covering portion at the first and second ends of the opening edge is 0.1 mm or more and 0.4 mm or less.

3. The interdental cleaning tool according to claim 1 or claim 2, wherein the first recess and the second recess are curved in a convex shape toward the center of the shaft in a cross-section which is perpendicular to the axial direction of the shaft.

4. The interdental cleaning tool according to claim 3, wherein the convex portion is defined in the cross-section by a first concave curved surface that defines the first recess, a second concave curved surface that defines the second recess, and a convex curved surface that curves convexly toward the opposite side of the center of the shaft portion and smoothly connects with the first concave curved surface and the second concave curved surface.

5. The interdental cleaning tool according to claim 4, wherein the angle of inclination of the line segment connecting the apex of the convex curved surface and the bottom of the first concave curved surface and the bottom of the second concave curved surface, with respect to the direction parallel to the width direction of the opening, is 15° or more and 65° or less.

6. The interdental cleaning tool according to claim 1 or claim 2, wherein the cleaning portion further includes a plurality of protrusions that protrude from the outer circumferential surface of the covering portion.

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