Ballpoint pen tip, ballpoint pen refill, and

Abstract

A ballpoint pen tip (40) has a ball (42) and a tip body (60) for holding the ball, and a first inclined surface (71) and a second inclined surface (72) disposed behind the first inclined surface are provided on an outer peripheral surface (70) of the tip body. In a cross-section including the central axis, the first inclined surface extends linearly obliquely with respect to both the axial direction (da) and the radial direction so as to face the outside in the radial direction (dr) as the rearward direction, and in a cross-section including the central axis, the second inclined surface extends linearly obliquely with respect to both the axial direction and the radial direction so as to face the outside in the radial direction as the rearward direction. The rear end (71b) of the first inclined surface and the front end (72a) of the second inclined surface are connected to each other, and the angle ([theta] 2) between the second inclined surface and the central axis is larger than the angle ([theta] 1) between the first inclined surface and the central axis.

Description

Technical Field

[0001] The invention relates to a ballpoint pen tip, a ballpoint pen core and a ballpoint pen. Background Art

[0002] Conventionally, a ballpoint pen tip having a ball and a nib body holding the ball is used in a ballpoint pen. JP6445754B2 discloses a ballpoint pen tip having a holder, wherein a reduced diameter portion whose outer diameter gradually decreases from the maximum outer diameter portion of the holder toward the front end to the vicinity of the crimping portion is provided at the front end of the holder, and the side surface of the reduced diameter portion is a concave curved surface. The ballpoint pen tip of JP6445754B2 has the following advantages: the writing ball of the pen tip and the line drawing portion formed thereby can be easily seen, and the design, rigidity and durability of the ballpoint pen tip can be improved.

[0003] The tip of a ballpoint pen tip is a portion that is visually recognized by the user when writing, and therefore it is required to further improve the design while sufficiently ensuring strength. Summary of the invention

[0004] The object of the present invention is to improve the design of a ballpoint pen tip.

[0005] Means for solving problems

[0006] [1] This embodiment provides a ballpoint pen tip, which has a ball and a nib body that holds the ball, wherein a first inclined surface and a second inclined surface arranged behind the first inclined surface are provided on the outer peripheral surface of the nib body, and in a cross section including a central axis, the first inclined surface extends linearly with respect to both the axial direction and the radial direction in a manner that is inclined toward the radial outside as it goes toward the rear, and in a cross section including the central axis, the second inclined surface extends linearly with respect to both the axial direction and the radial direction in a manner that is inclined toward the radial outside as it goes toward the rear, the rear end of the first inclined surface and the front end of the second inclined surface are connected to each other, and an angle θ2 between the second inclined surface and the central axis is larger than an angle θ1 between the first inclined surface and the central axis.

[0007] [2] A ballpoint pen tip according to [1], wherein a ratio L / L2 of the axial length L from the front end of the ball to the rear end of the first inclined surface to the axial length L2 of the second inclined surface is greater than 0.7 and less than 6.3.

[0008] [3] The ballpoint pen tip according to [1] or [2], wherein a ratio L1 / L2 of a length L1 in the axial direction of the first inclined surface to a length L2 in the axial direction of the second inclined surface is greater than or equal to 0.4 and less than or equal to 4.3.

[0009] [4] A ballpoint pen tip according to any one of [1] to [3], wherein the axial length L from the front end of the ball to the rear end of the first inclined surface is greater than or equal to 1.25 mm and less than or equal to 2.5 mm.

[0010] [5] The ballpoint pen tip according to any one of [1] to [4], wherein an angle θ1 between the first inclined surface and the central axis is greater than or equal to 4.0 degrees and less than or equal to 10 degrees.

[0011] [6] The ballpoint pen tip according to any one of [1] to [5], wherein an angle θ2 between the second inclined surface and the central axis is greater than or equal to 18 degrees and less than or equal to 40 degrees.

[0012] [7] A ballpoint pen tip according to any one of [1] to [6], wherein a ratio θ2 / θ1 of an angle θ2 between the second inclined surface and the central axis and an angle θ1 between the first inclined surface and the central axis is greater than 2.4 and less than 5.5.

[0013] [8] The ballpoint pen tip according to any one of [1] to [7], wherein the angle between the first inclined surface and the second inclined surface is greater than or equal to 146 degrees and less than or equal to 170 degrees.

[0014] [9] This embodiment provides a ballpoint pen refill having: a ballpoint pen tip as described in any one of [1] to [8]; and an ink storage tube for storing ink.

[0015]

[10] This embodiment provides a ballpoint pen, wherein the ballpoint pen has the ballpoint pen refill described in [9].

[0016] According to the present invention, the design of the ballpoint pen tip can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a diagram for explaining one embodiment of the present invention, and is a longitudinal sectional view showing an example of a ballpoint pen in which a ballpoint pen tip is assembled in a retracted state.

[0018] Figure 2 Shown in highlighted state Figure 1 Longitudinal section view of a ballpoint pen.

[0019] Figure 3 Yes Figure 2 An enlarged longitudinal section view of a ballpoint pen tip is shown.

[0020] Figure 4 Yes Figure 3 The figure shows an enlarged view of the site labeled IV.

[0021] Figure 5 It is a perspective view showing a part of the ballpoint pen tip.

[0022] Figure 6 This is a diagram showing the outer surface of a part of the ballpoint pen tip.

[0023] Figure 7 This is a longitudinal sectional view showing a part of the ballpoint pen tip.

[0024] Figure 8 Yes Figure 7 The figure shows an enlarged view of the part labeled VIII.

[0025] Fig. 9 is with Figure 8 The cross-sectional view corresponding to the IX-IX line.

[0026] Fig.10 This is a longitudinal sectional view showing an example of a ballpoint pen tip provided with a protective member.

[0027] Fig.11 This is a diagram showing an example of a method of providing a protective member.

[0028] Fig.12 This is a diagram showing an example of a method of providing a protective member.

[0029] Fig.13 This is a diagram showing an example of a method of providing a protective member.

[0030] Fig.14 This is a diagram for explaining a modified example of the present invention, and is a perspective view showing a part of a ballpoint pen tip.

[0031] Fig.15 This is a diagram showing the outer surface of a part of the ballpoint pen tip.

[0032] Fig.16 This is a longitudinal sectional view showing a part of the ballpoint pen tip.

[0033] Fig.17 Yes Fig.16 FIG. 1 is an enlarged view of the portion labeled XVII.

[0034] Fig.18 is with Fig.17 The cross-sectional view corresponding to the XVIII-XVIII line.

[0035] Fig.19 This is a diagram showing an example of a state in which the front end portion of a nib body enters into the inner hole of another nib body from the rear. DETAILED DESCRIPTION

[0036] Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings. In addition, in the drawings attached to this specification, for the sake of convenience of illustration and understanding, the scale and aspect ratio are appropriately changed and exaggerated relative to the scale and aspect ratio of the actual object.

[0037] In addition, the shapes, geometric conditions and the terms that determine their degrees, such as "parallel", "perpendicular", "same", lengths, angle values, etc. used in this specification are not limited to the strict meanings, but are interpreted to include the range of degrees that can be expected to have the same function.

[0038] In this specification, the direction in which the central axis A of the ballpoint pen 10 extends (the length direction, the up-down direction in the longitudinal cross-sectional view) is referred to as the axial direction da, the direction perpendicular to the axial direction da is referred to as the radial direction dr, and the direction along the circumference around the central axis A is referred to as the circumferential direction. In addition, along the axial direction da, the pen tip side is referred to as the front, and the side opposite to the pen tip is referred to as the rear. In addition, along the radial direction dr, the side close to the central axis A is referred to as the inner side or the inner side, and the side away from the central axis A is referred to as the outer side or the outer side.

[0039] Figure 1 FIG. 1 is a diagram for explaining one embodiment of the present invention, and is a longitudinal sectional view showing an example of a ballpoint pen 10 in a retracted state. Figure 2 The ballpoint pen 10 is a longitudinal sectional view showing a protruding state. The ballpoint pen 10 includes a barrel 20 , a ballpoint pen refill 30 assembled in the barrel 20 , and an ejection mechanism 12 for ejecting and ejecting the front end of the ballpoint pen refill 30 from the barrel 20 .

[0040] The barrel 20 includes a front shaft 22, a gripping member 24 disposed so as to surround the outer surface of the front shaft 22, a rear shaft 26 connected to the front shaft 22, and a clamp 28 disposed on the outer peripheral surface of the rear shaft 26. The central axis of the barrel 20 coincides with the central axis A of the ballpoint pen 10. The front shaft 22 has a front end opening 22a disposed at the front end, and the front end opening 22a allows the front end of the ballpoint pen tip 40 of the ballpoint pen refill 30 to be inserted and removed. The rear shaft 26 is mounted on the front shaft 22. In particular, in the example shown in the figure, the internal thread portion formed on the inner surface of the front end of the rear shaft 26 is screwed with the external thread portion formed on the outer surface of the rear end of the front shaft 22, thereby mounting the rear shaft 26 on the front shaft 22. When the user writes with the ballpoint pen 10, the user intends to grasp the gripping member 24 with fingers. The front shaft 22 and the rear shaft 26 are formed of, for example, resin, and the gripping member 24 is formed of, for example, rubber or an elastomer.

[0041] The retracting mechanism 12 is a mechanism for switching the ballpoint pen 10 alternately between a retracted state in which the front end portion of the ballpoint pen tip 40 is retracted from the front end opening 22a of the front shaft 22 and a protruding state in which the front end portion of the ballpoint pen tip 40 is protruded from the front end opening 22a. Figure 1 In the figure, the ballpoint pen 10 is shown in an immersed state. Figure 2 In the figure, the ballpoint pen 10 is shown in a protruding state. The ejection and retraction mechanism 12 includes an operating portion 14 and an elastic member 16. In the example shown in the figure, the operating portion 14 is a knocking member that protrudes rearward from the rear end of the barrel 20 (rear shaft 26). In addition, without being limited to this, the operating portion 14 may be, for example, a clamping member 28 that is configured to be movable forward and backward relative to the barrel 20 (rear shaft 26). The elastic member 16 is, for example, a coil spring. The elastic member 16 is configured in a compressed state between an inner step 22b formed on the inner surface of the barrel 20 (front shaft 22) and a front surface of a flange portion 54 formed on the outer surface of the connecting member 50 of the ballpoint pen refill 30 (refer to Figure 3 ).

[0042] like Figure 1 As shown, in the submerged state, the ballpoint pen refill 30 is forced backward by the elastic force of the elastic member 16, thereby the front end of the ballpoint pen tip 40 is submerged from the front end opening 22a. When the user presses the operating portion 14 forward with a finger, the ballpoint pen refill 30 moves forward, and the front end of the ballpoint pen tip 40 protrudes forward from the front end opening 22a. Even if the user removes the finger from the operating portion 14, the ballpoint pen refill 30 maintains the state where the front end of the ballpoint pen tip 40 protrudes forward from the front end opening 22a. When the user presses the operating portion 14 forward with a finger again, the ballpoint pen refill 30 moves forward a small distance. When the user removes the finger from the operating portion 14 or relaxes the pressure on the operating portion 14 forward, the ballpoint pen refill 30 is forced backward by the elastic force of the elastic member 16, so that the front end of the ballpoint pen tip 40 is submerged from the front end opening 22a. The emergence and retraction mechanism 12 that realizes such an emergence and retraction operation is well known, and therefore a detailed description thereof is omitted. As an example, an emergence and retraction mechanism having a rotary cam mechanism can be used as the emergence and retraction mechanism 12 .

[0043] The ballpoint pen refill 30 is stored in the barrel 20 in a manner that it can be retracted. The ballpoint pen refill 30 includes an ink storage cylinder 35 for storing ink and a ballpoint pen tip 40 installed at the front end of the ink storage cylinder 35. The central axis of the ballpoint pen refill 30 is consistent with the central axis A of the ballpoint pen 10. In addition, the central axis of the ink storage cylinder 35 and the central axis of the ballpoint pen tip 40 are consistent with the central axis A of the ballpoint pen 10. As the ink, ink that can be used for ballpoint pens can be used without particular restrictions. As an example, thermochromic ink can be used as the ink. The thermochromic ink can be a reversible thermochromic ink. As the reversible thermochromic ink, as an example, a heat-decolorizing type reversible thermochromic ink that changes from a color-forming state to a color-decolorizing state by heating and changes from a color-decolorizing state to a color-forming state by cooling can be used.

[0044] Figure 3 40 is a diagram showing a ballpoint pen tip 40. Figure 2 A longitudinal sectional view showing an enlarged view of the region marked with III. Figure 4 Yes Figure 3 The figure shows an enlarged view of the site labeled IV. Figure 5 1 is a perspective view showing a part of the ballpoint pen tip 40 , showing the ball 42 and the pen tip body 60 of the ballpoint pen tip 40 . Figure 6 1 is an outer surface view showing a part of the ballpoint pen tip 40 , and shows the ball 42 and the tip body 60 as viewed from the outside in the radial direction dr. Figure 7 It is a longitudinal sectional view showing the ball 42 and the pen tip body 60 . Figure 8 Yes Figure 7 The figure shows an enlarged view of the part labeled VIII.

[0045] The ballpoint pen tip 40 includes a ball 42 and a tip body 60. Figure 3 In the example shown, the ballpoint pen tip 40 further includes an elastic member 48 and a connecting member 50. The ballpoint pen tip 40 has an ink flow path 45. The ink flow path 45 penetrates the ballpoint pen tip 40 along the axial direction da. The ink stored in the ink storage cylinder 35 flows toward the ball 42 through the ink flow path 45. In the example shown in the figure, the ink flow path 45 includes an inner hole 51 described later of the connecting member 50, an inner hole 67 described later of the pen tip body 60, and a ball holding chamber 61.

[0046] The connecting member 50 is a member having a substantially cylindrical shape and is mounted on the front end of the ink container 35. In particular, the connecting member 50 is mounted on the ink container 35 by inserting the rear end of the connecting member 50 into the front end of the ink container 35. The connecting member 50 has the function of connecting the ink container 35 and the pen tip body 60. Figure 3In the example shown, the connecting member 50 is composed of a single member, but is not limited thereto, and the connecting member 50 may also be composed of a combination of two or more members. The connecting member 50 has an inner hole 51, a flange portion 54, and an inner step 55. The inner hole 51 is a through hole that penetrates the connecting member 50 along the axial direction da. The inner hole 51 constitutes a part of the ink flow path 45.

[0047] The flange 54 protrudes outward in the radial direction dr from the outer peripheral surface of the connecting member 50. In the example shown in the figure, the front end of the ink container 35 contacts the rear surface of the flange 54. The rear end of the elastic member 16 contacts the front surface of the flange 54.

[0048] The inner step 55 is a step portion provided in the inner hole 51. In the example shown in the figure, the inner hole 51 includes a small diameter portion and a large diameter portion located in front of the small diameter portion and having an inner diameter larger than the small diameter portion, and the inner step 55 is a step portion provided at the boundary portion between the small diameter portion and the large diameter portion. The rear portion of the elastic member 48 is arranged in the inner hole 51 of the connecting member 50.

[0049] The elastic member 48 has a spring portion 48a and a rod portion 48b extending forward from the spring portion 48a and contacting the ball 42 from the rear. The spring portion 48a is composed of, for example, a coil spring. The rear end of the rod portion 48b is connected to the spring portion 48a, and the front end of the rod portion 48b contacts the ball 42 from the rear. In the illustrated example, the rear end of the spring portion 48a contacts the inner step 55 of the connecting member 50. In this state, the spring portion 48a is in a compressed state, and the elastic member 48 generates a force in the direction in which the spring portion 48a is extended. The rod portion 48b transmits the force of the spring portion 48a to the ball 42. Thus, the force applied to the ball 42 forward always acts on the ball 42.

[0050] The nib body 60 is a component that holds the ball 42. The nib body 60 has a ball holding chamber 61, a front end 63, a rear end 65, an inner hole 67, and an outer peripheral surface 70. In the example shown in the figure, the nib body 60 is attached to the connecting member 50. In particular, the nib body 60 is attached to the connecting member 50 by inserting the rear end 65 of the nib body 60 into the front end of the connecting member 50.

[0051] The ball holding chamber 61 has the function of holding the ball 42, and has the function of holding ink in the ball holding chamber 61 and making the ink adhere to the ball 42. The ball holding chamber 61 is composed of a hole portion formed from the front end of the nib body 60 toward the rear. In the illustrated example, after the ball 42 is arranged in the ball holding chamber 61, the front end portion 63 of the nib body 60 is deformed toward the inner side (center axis A side) of the radial direction dr, thereby holding the ball 42 in the ball holding chamber 61. The front end portion 63 protrudes inward at the front end of the nib body 60 and can be in annular contact with a part of the front side of the ball 42. The inner surface of the front end portion 63 is in the shape of a truncated conical surface. A part of the ball 42 protrudes forward from the ball holding chamber 61. In addition, another part of the ball 42 can also protrude backward from the ball holding chamber 61.

[0052] The inner hole 67 is a through hole that penetrates the nib body 60 in the axial direction da. The inner hole 67 constitutes a part of the ink flow path 45. In this embodiment, the front part of the elastic member 48 is located in the inner hole 67. In particular, the rod portion 48b of the elastic member 48 is located in the inner hole 67.

[0053] The outer peripheral surface 70 is a surface facing the outside of the radial direction dr in the pen tip body 60. The outer peripheral surface 70 includes not only a surface whose normal direction coincides with the radial direction dr, but also a surface whose normal direction is inclined relative to the radial direction dr. In particular, the outer peripheral surface 70 includes a surface whose normal direction is inclined forward or backward relative to the radial direction dr.

[0054] In the present embodiment, the outer peripheral surface 70 includes a first inclined surface 71 and a second inclined surface 72. In the present embodiment, the outer peripheral surface 70 further includes a third inclined surface 73, a fourth inclined surface 74, a rear outer peripheral surface 75, a connecting surface 76, and a front end outer peripheral surface 77.

[0055] In the cross section containing the central axis A (refer to Figure 4 , Figure 7 , Figure 8 ), the first inclined surface 71 extends linearly with respect to both the axial direction da and the radial direction dr in a manner that is inclined toward the outside of the radial direction dr as it moves toward the rear. In other words, the normal line of the first inclined surface 71 extends linearly with respect to both the axial direction da and the radial direction dr in a manner that is inclined toward the front as it moves toward the outside of the radial direction dr.

[0056] The second inclined surface 72 is arranged behind the first inclined surface 71. In the cross section including the central axis A, the second inclined surface 72 extends linearly with respect to both the axial direction da and the radial direction dr in a manner that is inclined toward the outside of the radial direction dr as it goes toward the rear. In other words, the normal line of the second inclined surface 72 extends linearly with respect to both the axial direction da and the radial direction dr in a manner that is inclined toward the front as it goes toward the outside of the radial direction dr.

[0057] The first inclined surface 71 has a front end 71a and a rear end 71b, and the second inclined surface 72 has a front end 72a and a rear end 72b. The rear end 71b of the first inclined surface 71 and the front end 72a of the second inclined surface 72 are connected to each other to form a connecting portion 78. Thus, in the cross section including the central axis A, the first inclined surface 71 and the second inclined surface 72 are connected in a broken line shape at the connecting portion 78.

[0058] When writing with the ballpoint pen 10, a force is applied to the front end of the nib body 60 by the reaction force relative to the pen pressure. In particular, the component force in the radial direction dr acts on the front end of the nib body 60. In this case, the moment generated by the component force in the radial direction dr increases as it moves toward the rear of the nib body 60. The nib body 60 of this embodiment has a first inclined surface 71 and a second inclined surface 72 that are inclined in a manner toward the outside of the radial direction dr as it moves toward the rear, so that the dimension (diameter) in the direction perpendicular to the center axis A increases as it moves toward the rear. That is, in the nib body 60 of this embodiment, the area of ​​the cross section perpendicular to the center axis A increases as it moves toward the rear. Therefore, in the rear part of the nib body 60, the moment generated by the component force in the radial direction 10dr can be borne with a relatively large cross-sectional area. As a result, the strength of the nib body 60 can be effectively improved.

[0059] The angle θ1 between the first inclined surface 71 and the axial direction da (see Figure 8 ) is preferably greater than 4.0 degrees and less than 10 degrees. Since the axial direction da is parallel to the central axis A, the angle θ1 between the first inclined surface 71 and the axial direction da is equal to the angle between the first inclined surface 71 and the central axis A. Therefore, in this specification, the angle between the first inclined surface 71 and the central axis A is also expressed as θ1. More preferably, the angle θ1 is greater than 5.5 degrees and less than 9 degrees. Further preferably, the angle θ1 is greater than 7.0 degrees and less than 8 degrees.

[0060] The angle θ2 between the second inclined surface 72 and the axial direction da (see Figure 8 ) is preferably 18 degrees or more and 40 degrees or less. The angle θ2 between the second inclined surface 72 and the axial direction da is equal to the angle between the second inclined surface 72 and the central axis A. Therefore, in this specification, the angle between the second inclined surface 72 and the central axis A is also expressed as θ2. More preferably, the angle θ2 is 20 degrees or more and 35 degrees or less. Further preferably, the angle θ2 is 25 degrees or more and 30 degrees or less.

[0061] The angle θ2 between the second inclined surface 72 and the central axis A is larger than the angle θ1 between the first inclined surface 71 and the central axis A. In other words, the angle θ1 between the first inclined surface 71 and the central axis A is smaller than the angle θ2 between the second inclined surface 72 and the central axis A. As a result, the diameter of the nib body 60 becomes smaller near the front end of the nib body 60. Therefore, the writing surface such as paper becomes easier to visually confirm.

[0062] In addition, in the cross section including the central axis A, the first inclined surface 71 and the second inclined surface 72 are respectively formed of straight lines, so that the pen tip body 60 has a stylish appearance (see FIG. Figure 5 ). In particular, in this embodiment, a circular line (connecting portion 78) extending in the circumferential direction is visually confirmed between the first inclined surface 71 and the second inclined surface 72. This circular line attracts the user's eyes, and the pen tip body 60 presents a characteristic appearance. As a result, compared with the ballpoint pen tip in which the side surface of the reduced diameter portion is a concave curved surface as in the prior art, the design can be effectively improved.

[0063] The ratio θ2 / θ1 of the angle θ2 between the second inclined surface 72 and the central axis A to the angle θ1 between the first inclined surface 71 and the central axis A is preferably 2.4 or more and 5.5 or less. More preferably, the ratio θ2 / θ1 is 3.0 or more and 5.0 or less. Further preferably, the ratio θ2 / θ1 is 3.5 or more and 4.5 or less.

[0064] An angle θ3 between the first inclined surface 71 and the second inclined surface 72 (see Figure 8 ) is preferably 146 degrees or more and 170 degrees or less. More preferably, the angle θ3 is 150 degrees or more and 165 degrees or less. Further preferably, the angle θ3 is 155 degrees or more and 160 degrees or less.

[0065] In addition, according to Figure 8 It can be understood that both angles θ1 and θ2 are acute angles, and angle θ3 is an obtuse angle.

[0066] The length da in the axial direction from the front end of the ball 42 to the rear end 71b of the first inclined surface 71 is represented by L. The length da in the axial direction of the first inclined surface is represented by L1. The length da in the axial direction of the second inclined surface 72 is represented by L2.

[0067] At this time, the length L is preferably 1.25 mm or more and 2.5 mm or less. More preferably, the length L is 1.75 mm or more and 2.25 mm or less. Further preferably, the length L is 1.8 mm or more and 2.0 mm or less.

[0068] The length L1 is preferably not less than 0.54 mm and not more than 1.85 mm. More preferably, the length L1 is not less than 0.79 mm and not more than 1.69 mm. Further preferably, the length L1 is not less than 1.05 mm and not more than 1.55 mm.

[0069] The length L2 is preferably 0.36 mm or more and 1.71 mm or less. More preferably, the length L2 is 0.5 mm or more and 1.46 mm or less. Further preferably, the length L2 is 0.71 mm or more and 1.25 mm or less.

[0070] The ratio L / L2 of the length L to the length L2 is preferably 0.7 or more and 6.3 or less. More preferably, the ratio L / L2 is 1.0 or more and 4.5 or less. Further preferably, the ratio L / L2 is 2.0 or more and 3.0 or less.

[0071] In addition, the ratio L1 / L2 of the length L1 to the length L2 is preferably 0.4 or more and 4.3 or less. More preferably, the ratio L1 / L2 is 0.65 or more and 3.6 or less. Further preferably, the ratio L1 / L2 is 1.3 or more and 2.3 or less.

[0072] In the present embodiment, the first inclined surface 71 and the second inclined surface 72 are located behind the ball 42. In other words, when viewed from the radial direction dr, the first inclined surface 71 and the second inclined surface 72 do not overlap with the ball 42. In addition, the first inclined surface 71 and the second inclined surface 72 are located behind the ball holding chamber 61. In other words, when viewed from the radial direction dr, the first inclined surface 71 and the second inclined surface 72 do not overlap with the ball holding chamber 61.

[0073] The third inclined surface 73 is arranged behind the second inclined surface 72. In the cross section including the central axis A, the third inclined surface 73 extends linearly with respect to both the axial direction da and the radial direction dr in a manner inclined toward the outside of the radial direction dr as it goes toward the rear. The rear end 72b of the second inclined surface 72 and the front end of the third inclined surface 73 are connected to each other. The angle between the third inclined surface 73 and the central axis A is smaller than the angle θ2 between the second inclined surface 72 and the central axis A.

[0074] The fourth inclined surface 74 is arranged in front of the first inclined surface 71. In the cross section including the central axis A, the fourth inclined surface 74 extends linearly with respect to both the axial direction da and the radial direction dr in a manner inclined toward the outside of the radial direction dr as it goes toward the rear. The rear end of the fourth inclined surface 74 and the front end 71a of the first inclined surface 71 are connected to each other via a connecting surface 76. The angle between the fourth inclined surface 74 and the central axis A is larger than the angle θ1 between the first inclined surface 71 and the central axis A. In addition, the angle between the fourth inclined surface 74 and the central axis A is smaller than the angle θ2 between the second inclined surface 72 and the central axis A.

[0075] The connecting surface 76 is arranged between the first inclined surface 71 and the fourth inclined surface 74. In the cross section including the central axis A, the fourth inclined surface 74 extends linearly with respect to both the axial direction da and the radial direction dr in a manner inclined toward the outside of the radial direction dr as it goes toward the rear. The front end of the connecting surface 76 is connected to the rear end of the fourth inclined surface 74, and the rear end of the connecting surface 76 is connected to the front end 71a of the first inclined surface 71. The angle between the connecting surface 76 and the central axis A is larger than the angle θ1 between the first inclined surface 71 and the central axis A. In addition, the angle between the connecting surface 76 and the central axis A is larger than the angle between the fourth inclined surface 74 and the central axis A.

[0076] The rear outer peripheral surface 75 is arranged behind the third inclined surface 73. The rear outer peripheral surface 75 is a cylindrical surface extending along the axial direction da and the circumferential direction. The central axis of the rear outer peripheral surface 75 coincides with the central axis A of the ballpoint pen 10. The front end of the rear outer peripheral surface 75 and the rear end of the third inclined surface 73 are connected to each other.

[0077] The front end outer peripheral surface 77 is a surface formed on the outer periphery of the front end portion 63. In the cross section including the central axis A, the front end outer peripheral surface 77 extends linearly with respect to both the axial direction da and the radial direction dr in a manner inclined toward the outside of the radial direction dr as it goes toward the rear. The rear end of the front end outer peripheral surface 77 is connected to the front end of the fourth inclined surface 74. The angle between the front end outer peripheral surface 77 and the central axis A is larger than the angle θ1 between the first inclined surface 71 and the central axis A. In addition, the angle between the front end outer peripheral surface 77 and the central axis A is larger than the angle between the fourth inclined surface 74 and the central axis A.

[0078] Fig. 9 is with Figure 8 A cross-sectional view corresponding to the line IX-IX of FIG. A cross-sectional view perpendicular to the central axis A at the connecting portion 78 of the first inclined surface 71 and the second inclined surface 72 (see FIG. Fig. 9), the size (outer diameter) of the connection portion 78 is set to D1, and the size (inner diameter) of the inner hole 67 is set to D2. When the connection portion 78 has a circular shape in a cross section perpendicular to the central axis A, the size D1 of the connection portion 78 can also be said to be the diameter or outer diameter of the connection portion 78. In addition, when the inner hole 67 has a circular shape in a cross section perpendicular to the central axis A, the size D2 of the inner hole 67 can also be said to be the diameter or inner diameter of the inner hole 67.

[0079] In the present embodiment, the ratio D1 / D2 of the dimension D1 of the connection portion 78 to the dimension D2 of the inner hole 67 is preferably greater than 1.1 and less than 2.1. When the ballpoint pen 10 is used for writing, when the component force in the radial direction dr acts on the front end of the nib body 60, a relatively large force can be applied to the cross section perpendicular to the central axis A at the connection portion 78. In the present embodiment, by setting the ratio D1 / D2 to greater than 1.1 and less than 2.1, the dimension D1 of the connection portion 78 can be made sufficiently large relative to the dimension D2 of the inner hole 67. Thus, the wall thickness of the nib body 60 at the connection portion 78 can be sufficiently ensured. Therefore, the strength of the nib body 60 can be more effectively improved. It is more preferred that the ratio D1 / D2 is greater than 1.2 and less than 1.8. It is further preferred that the ratio D1 / D2 is greater than 1.3 and less than 1.6.

[0080] The area of ​​the nib body 60 within the range of ±0.5 mm in the axial direction da with the connection portion 78 as the center is defined as area R (see Figure 8 ). The region R includes the range from the connection portion 78 to the portion 0.5 mm away from the front and the range from the connection portion 78 to the portion 0.5 mm away from the rear. That is, the length of the region R along the axial direction da is 1 mm. The minimum value T of the wall thickness of the pen tip body 60 in the region R is min It is preferably 0.10 mm or more and 0.26 mm or less. min By setting T to be 0.10 mm or more, the wall thickness of the nib body 60 near the connection portion 78 can be sufficiently ensured. Therefore, the strength of the nib body 60 can be more effectively improved. min When T is set to 0.26 mm or less, it is possible to suppress the pen tip body 60 from becoming larger. min is 0.12 mm or more and 0.25 mm or less. It is further preferred that T min The wall thickness of the pen tip body 60 refers to the dimension along the radial direction dr between the outer peripheral surface 70 and the inner wall of the inner hole 67. Figure 8 In the example shown, the nib body 60 has a wall thickness T min The portion of the pen tip body 60 having a wall thickness T is located in front of the connecting portion 78, but is not limited thereto.min The portion may be located further rearward than the connection portion 78.

[0081] In order to protect the front end portion of the ballpoint pen tip 40 , a protective member 80 formed of a resin material or the like may be provided at the front end portion of the ballpoint pen tip 40 . Fig.10 This is a longitudinal sectional view showing an example of a ballpoint pen tip 40 in which a protective member 80 is provided at the front end portion.

[0082] exist Fig.10 In the example shown, a protective member 80 is provided at the front end of the ballpoint pen tip 40. The protective member 80 is also generally referred to as a resin bead. The protective member 80 is formed to cover the front end of the ballpoint pen tip 40. In the example shown in the figure, the protective member 80 covers the ball 42, the front end outer peripheral surface 77 of the pen tip body 60, the fourth inclined surface 74, the connecting surface 76, and the first inclined surface 71.

[0083] The protective member 80 may also be formed of a mixture of a thermoplastic resin, an adhesive resin, and wax. The protective member 80 can be fixed to the front end of the ballpoint pen tip 40 by heating and melting the mixture and solidifying it after it is attached to the front end of the ballpoint pen tip 40. By providing such a protective member 80 at the front end of the ballpoint pen tip 40, it is possible to suppress the solvent component in the ink from volatilizing through the gap that may be generated between the front end portion 63 of the nib body 60 and the ball 42.

[0084] In addition, examples of the thermoplastic resin include ethylene-vinyl acetate copolymer, polyethylene, polyacetal, polyester, polycarbonate, polyamide, polyvinyl ether, etc. Examples of the adhesive resin include terpene resin, coumarone resin, phenolic resin, ester gum, and gum rosin. Examples of the wax include paraffin wax, microcrystalline wax, carnauba wax, polyethylene wax, natural wax, fatty acid wax, etc.

[0085] The protective component 80 is attached to the front end of the ballpoint pen tip 40 (tip body 60) during the manufacturing process of the ballpoint pen 10. The protective component 80 is attached to the ballpoint pen tip 40 by the adhesive force of the protective component 80 itself. The manufactured ballpoint pen 10 can be sold in a state where the protective component 80 is attached to the front end of the ballpoint pen tip 40. In this case, the user removes the protective component 80 from the ballpoint pen tip 40 before starting to use the ballpoint pen 10. The user usually applies force to the protective component 80 forward with his fingers, thereby removing the protective component 80 from the ballpoint pen tip 40.

[0086] The rear end of the protective member 80 may also be located at the connection portion 78 of the nib body 60. In this case, the entire first inclined surface 71 may be covered by the protective member 80. In addition, the entire second inclined surface 72 may be exposed from the protective member 80. When the rear end of the protective member 80 is located at the connection portion 78, the user's fingers are easily hooked on the rear end of the protective member 80. Therefore, the user can easily remove the protective member 80 from the ballpoint pen nib 40.

[0087] In the case where the surface constituting the front end of the nib body 60 extends parallel to the axial direction da, that is, in the case where the front end of the nib body 60 has a cylindrical shape extending along the axial direction da, even if the user applies force to the protective member 80 forward with a finger, force is applied in a direction parallel to the interface between the nib body 60 and the protective member 80. Therefore, it is difficult to apply force to the protective member 80 to peel the protective member 80 from the nib body 60. That is, in the case where the front end of the nib body 60 has a cylindrical shape, it may be difficult to remove the protective member 80 from the nib body 60.

[0088] exist Fig.10 In the example shown, the rear portion of the protective member 80 is located on the first inclined surface 71. Thus, when the user applies force to the protective member 80 forward with a finger, a force that causes the protective member 80 to be peeled off from the pen tip body 60 can be applied to the protective member 80. Therefore, the protective member 80 can be easily removed from the pen tip body 60.

[0089] In particular, the angle θ1 between the first inclined surface 71 and the axial direction da (see Figure 8 ) is preferably greater than 4.0 degrees and less than 10 degrees. By having the angle θ1 be greater than 4.0 degrees, when the user applies force to the protective component 80 forward with his fingers, a force that causes the protective component 80 to be peeled off from the nib body 60 can be effectively applied to the protective component 80. In addition, by having the angle θ1 be less than 10 degrees, when the protective component 80 contacts other components (including the user's fingers, etc.), it is possible to prevent the protective component 80 from accidentally peeling off from the nib body 60. More preferably, the angle θ1 is greater than 5.5 degrees and less than 9 degrees. Even more preferably, the angle θ1 is greater than 7.0 degrees and less than 8 degrees.

[0090] When the protective member 80 is provided, as described later, the tip of the ballpoint pen tip 40 is immersed in a resin material 82 having fluidity. Fig.10 In the example shown, the nib body 60 has a second inclined surface 72 located behind the first inclined surface 71 and having an angle θ2 greater than the angle θ1 of the first inclined surface 71. Thus, when the front end of the ballpoint pen nib 40 is immersed in the resin material 82, the protective member 80 can be prevented from flowing and moving backward beyond the connecting portion 78.

[0091] The angle θ2 between the second inclined surface 72 and the axial direction da (see Figure 8 ) is preferably 18 degrees or more and 40 degrees or less. If the angle θ2 is 18 degrees or more and 40 degrees or less, when the front end of the ballpoint pen tip 40 is immersed in the resin material 82, it is possible to effectively prevent the protective component 80 from flowing backwards and moving relative to the connecting portion 78. More preferably, the angle θ2 is 20 degrees or more and 35 degrees or less. It is further preferred that the angle θ2 is 25 degrees or more and 30 degrees or less.

[0092] Next, refer to Figure 11 to Figure 13 , an example of a method of providing a protective member 80 at the front end portion of the ballpoint pen tip 40 is described.

[0093] First, a resin material 82 having fluidity is prepared. Fig.11 In the example shown, the resin material 82 is contained in a container 84. Fig.12 As shown in FIG. 1 , the tip of the ballpoint pen tip 40 is immersed in a resin material 82 having fluidity. At this time, the ballpoint pen tip 40 is immersed in the resin material 82 in such a manner that the connection portion 78 of the pen tip body 60 is aligned with the liquid surface of the resin material 82. That is, the ballpoint pen tip 40 is immersed in the resin material 82 until the entire first inclined surface 71 is immersed in the resin material 82. In this case, the connection portion 78 functions as a mark for visually confirming the immersion depth of the ballpoint pen tip 40. Next, as shown in FIG. Fig.13 As shown, the ballpoint pen tip 40 is pulled up from the resin material 82. Then, the resin material 82 is dried or hardened, and the protective member 80 is manufactured from the resin material 82.

[0094] The ballpoint pen tip 40 of the present embodiment is a ballpoint pen tip 40 having a ball 42 and a nib body 60 for holding the ball 42, wherein a first inclined surface 71 and a second inclined surface 72 arranged behind the first inclined surface 71 are provided on the outer peripheral surface 70 of the nib body 60, and in a cross section including the central axis A, the first inclined surface 71 extends linearly with respect to both the axial direction da and the radial direction dr in a manner inclined toward the outside of the radial direction dr as it goes toward the rear, and in a cross section including the central axis A, the second inclined surface 72 extends linearly with respect to both the axial direction da and the radial direction dr in a manner inclined toward the outside of the radial direction dr as it goes toward the rear, the rear end 71b of the first inclined surface 71 and the front end 72a of the second inclined surface 72 are connected to each other, and the angle θ2 between the second inclined surface 72 and the central axis A is larger than the angle θ1 between the first inclined surface 71 and the central axis A.

[0095] In the ballpoint pen tip 40 of this embodiment, a ratio L / L2 of an axial length L from the front end of the ball 42 to the rear end 71b of the first inclined surface 71 to an axial length L2 of the second inclined surface 72 is greater than or equal to 0.7 and less than or equal to 6.3.

[0096] In the ballpoint pen tip 40 of the present embodiment, a ratio L1 / L2 of a length L1 of the first inclined surface 71 in the axial direction da to a length L2 of the second inclined surface 72 in the axial direction da is greater than or equal to 0.4 and less than or equal to 4.3.

[0097] In the ballpoint pen tip 40 of the present embodiment, the length L in the axial direction da from the front end of the ball 42 to the rear end 71 b of the first inclined surface 71 is 1.25 mm or more and 2.5 mm or less.

[0098] In the ballpoint pen tip 40 of the present embodiment, an angle θ1 between the first inclined surface 71 and the central axis A is greater than or equal to 4.0 degrees and less than or equal to 10 degrees.

[0099] In the ballpoint pen tip 40 of the present embodiment, an angle θ2 between the second inclined surface 72 and the central axis A is greater than or equal to 18 degrees and less than or equal to 40 degrees.

[0100] In the ballpoint pen tip 40 of the present embodiment, a ratio θ2 / θ1 of an angle θ2 between the second inclined surface 72 and the central axis A to an angle θ1 between the first inclined surface 71 and the central axis A is greater than or equal to 2.4 and less than or equal to 5.5.

[0101] In the ballpoint pen tip 40 of the present embodiment, an angle θ3 between the first inclined surface 71 and the second inclined surface 72 is greater than or equal to 146 degrees and less than or equal to 170 degrees.

[0102] The ballpoint pen refill 30 of the present embodiment includes the above-mentioned ballpoint pen tip 40 and an ink storage tube 35 that stores ink.

[0103] The ballpoint pen 10 of this embodiment includes the above-mentioned ballpoint pen refill 30 .

[0104] When writing with a ballpoint pen, a force acts on the front end of the nib body 60 through the reaction force relative to the pen pressure. In particular, the component force in the radial direction dr acts on the front end of the nib body 60. In this case, the moment generated by the component force in the radial direction dr increases as it moves toward the rear of the nib body 60. The ballpoint pen tip 40, the ballpoint pen refill 30, and the ballpoint pen 10 of this embodiment have a first inclined surface 71 and a second inclined surface 72 that are inclined in a manner that is inclined toward the outside of the radial direction dr as it moves toward the rear, so the dimension (diameter) in the direction perpendicular to the center axis A increases as it moves toward the rear. That is, in the nib body 60 of this embodiment, the area of ​​the cross section perpendicular to the center axis A increases as it moves toward the rear. Therefore, in the rear part of the nib body 60, the moment generated by the component force in the radial direction dr can be borne with a relatively large cross-sectional area. As a result, the strength of the nib body 60 can be effectively improved.

[0105] In addition, the angle θ2 between the second inclined surface 72 and the central axis A is larger than the angle θ1 between the first inclined surface 71 and the central axis A. In other words, the angle θ1 between the first inclined surface 71 and the central axis A is smaller than the angle θ2 between the second inclined surface 72 and the central axis A. As a result, the diameter of the nib body 60 becomes smaller near the front end of the nib body 60. Therefore, it is easy to visually confirm the writing surface such as paper.

[0106] Furthermore, in the cross section including the central axis A, the first inclined surface 71 and the second inclined surface 72 are respectively formed of straight lines, so that the pen tip body 60 has a stylish appearance (see FIG. Figure 5 ). In particular, in this embodiment, a circular line extending in the circumferential direction is visually confirmed between the first inclined surface 71 and the second inclined surface 72. The circular line attracts the user's eyes, and the pen tip body 60 presents a characteristic appearance. As a result, compared with the ballpoint pen tip in the prior art in which the side surface of the reduced diameter portion is a concave curved surface, the design can be effectively improved.

[0107] Reference Figures 14 to 19 In the following description and the drawings used in the following description, for parts that can be configured in the same manner as the above-mentioned embodiment, the same reference numerals as those used for corresponding parts in the above-mentioned embodiment are used, and repeated descriptions are omitted.

[0108] The nib body is provided with an ink flow path for supplying ink stored in the ink storage cylinder of the ballpoint pen core to the ball. The rear end of the ink flow path opens at the rear end of the nib body. That is, the nib body has an inner hole opened at the rear end of the nib body.

[0109] When assembling a ballpoint pen refill, a nib body with a ball installed is provided by a component supply device (parts supply). In the component supply device, vibration is applied to, for example, a storage portion that stores a plurality of components (nib bodies). Through this vibration, for example, the components are oriented in a prescribed direction, the components are arranged, and the components are transported in a prescribed direction. When the nib bodies are provided by the component supply device, sometimes the front end of the nib body enters an inner hole opened at the rear end of another nib body. In this case, the front end of the nib body contacts the inner hole of the other nib body, and there is a possibility that damage will occur to the front end of the nib body.

[0110] The purpose of this modification is to suppress damage to the tip of the pen tip body.

[0111] The overall structure of the ballpoint pen 10 in this modified example is similar to that of the reference Figure 1 to Figure 4 The ballpoint pen 10 described is the same, so the detailed description is omitted.

[0112] Fig.14 This is a diagram for explaining the present modification, and is a perspective view showing a part of a ballpoint pen tip 40 . Fig.14 The ball 42 and the tip body 60 of the ballpoint pen tip 40 are shown. Fig.15 1 is an outer surface view showing a part of the ballpoint pen tip 40 , and shows the ball 42 and the tip body 60 as viewed from the outside in the radial direction dr. Fig.16 It is a longitudinal sectional view showing the ball 42 and the pen tip body 60 . Fig.17 Yes Fig.16 FIG. 1 is an enlarged view of the portion labeled XVII. Fig.18 is with Fig.17 The cross-sectional view corresponding to the XVIII-XVIII line.

[0113] like Fig.14 and Fig.15 As shown, the nib body 60 has a rear end 65a. The rear end 65a is the rear edge of the nib body 60. In particular, the rear end 65a is the rear edge of the rear end portion 65 of the nib body 60.

[0114] like Fig.16 As shown, the inner hole 67 of the nib body 60 opens toward the rear at the rear end 65a of the nib body 60. The inner hole 67 has an inner diameter D3 at the rear end 65a. In the case where the inner hole 67 has a circular contour when viewed from the rear, the inner diameter D3 is the diameter of the inner hole 67. In this modified example, the outer diameter D1 of the connecting portion 78 is less than the inner diameter D3 of the inner hole 67 at the rear end 65a of the nib body 60. That is, D1≤D3. In addition, the outer diameter D1 of the connecting portion 78 may be smaller than the inner diameter D3 of the inner hole 67 at the rear end 65a of the nib body 60. That is, D1<D3. Refer to Fig.19The reason why D1 and D3 have such a magnitude relationship in this modification example will be described.

[0115] In this modification, when assembling the ballpoint pen refill 30, the nib body 60 with the ball 42 mounted thereon is provided by a component supply device. In the component supply device, for example, vibration is applied to a storage portion that stores a plurality of nib bodies 60. By this vibration, for example, the nib bodies 60 are oriented in a predetermined direction, the nib bodies 60 are arranged, and the nib bodies 60 are transported in a predetermined direction. When the nib bodies 60 are provided by the component supply device, the front end of the nib body 60 may enter the inner hole 67 opened at the rear end 65a of another nib body 60.

[0116] Fig.19 1 is a diagram showing an example of a state in which the front end portion of the nib body 60 enters from the rear into the inner hole 67 of another nib body 60 in this modification. Fig.19 Three pen tip bodies 60 are shown in FIG. Fig.19 The three nib bodies 60 are set as the first nib body 601, the second nib body 602 and the third nib body 603 from the left. Fig.19 In the example shown, the tip of the second nib body 602 enters the inner hole 67 of the first nib body 601. In addition, the tip of the third nib body 603 enters the inner hole 67 of the second nib body 602.

[0117] The following description will be made by taking the first nib body 601 and the second nib body 602 as examples. In the nib bodies 601 and 602, when the outer diameter D1 of the connection portion 78 is larger than the inner diameter D3 of the inner hole 67 at the rear end 65a of the nib body 60, when the front end of the second nib body 602 enters the inner hole 67 of the first nib body 601 from the rear, the first inclined surface 71 of the second nib body 602 contacts the rear end of the inner hole 67 of the first nib body 601. Since the angle θ1 between the first inclined surface 71 and the central axis A is smaller than the angle θ2 between the second inclined surface 72 and the central axis A, when the first inclined surface 71 of the second nib body 602 contacts the rear end of the inner hole 67 of the first nib body 601, the fitting force acting between the first inclined surface 71 of the second nib body 602 and the rear end of the inner hole 67 of the first nib body 601 becomes relatively large. This makes it difficult for the second nib body 602 to fall off from the first nib body 601 , and it is easy for the first inclined surface 71 of the second nib body 602 to be damaged.

[0118] In contrast, in the present modification, in the nib bodies 601 and 602, the outer diameter D1 of the connection portion 78 is less than the inner diameter D3 of the inner hole 67 at the rear end 65a of the nib body 60. Thus, when the front end of the second nib body 602 enters the inner hole 67 of the first nib body 601 from the rear, the first inclined surface 71 of the second nib body 602 can completely enter the inner hole 67 of the first nib body 601. In addition, the rear end 65a of the first nib body 601 can contact the connection portion 78 or the second inclined surface 72 of the second nib body 602. Thus, damage to the first inclined surface 71 of the second nib body 602 can be effectively suppressed. In addition, since the angle θ2 between the second inclined surface 72 and the central axis A is larger than the angle θ1 between the first inclined surface 71 and the central axis A, when the second inclined surface 72 of the second nib body 602 contacts the rear end of the inner hole 67 of the first nib body 601, the fitting force acting between the second inclined surface 72 of the second nib body 602 and the rear end of the inner hole 67 of the first nib body 601 becomes relatively small. As a result, the second nib body 602 is easy to fall off from the first nib body 601, and the second inclined surface 72 of the second nib body 602 is not easy to be damaged.

[0119] In addition, the inner diameter D3 of the inner hole 67 at the rear end 65 a of the pen tip body 60 may be smaller than the outer diameter D4 at the rear end 72 b of the second inclined surface 72 .

[0120] The angle θ1 between the first inclined surface 71 and the central axis A is preferably not less than 4.0 degrees and not more than 10 degrees. When the angle θ1 is not less than 4.0 degrees, when the front end of the second nib body 602 enters the inner hole 67 of the first nib body 601 from the rear, when the central axis of the second nib body 602 is inclined relative to the central axis of the first nib body 601, it is possible to suppress the vicinity of the ball 42 of the second nib body 602 from contacting the inner hole 67 of the first nib body 601. Thus, it is possible to suppress damage to the ball 42 and the front end 63. Therefore, it is possible to suppress ink leakage from between the ball 42 and the front end 63 due to damage to the ball 42 and the front end 63. In addition, when the angle θ1 is not more than 10 degrees, the outer diameter D1 of the connecting portion 78 can be reduced. Thus, the diameter of the nib body 60 near the front end of the nib body 60 becomes smaller, and the writing surface such as paper becomes easier to visually confirm. More preferably, the angle θ1 is not less than 5.5 degrees and not more than 9 degrees. Still more preferably, the angle θ1 is not less than 7.0 degrees and not more than 8 degrees.

[0121] The angle θ2 between the second inclined surface 72 and the central axis A is preferably greater than 18 degrees and less than 40 degrees. By setting the angle θ2 to be greater than 18 degrees, when the second inclined surface 72 of the second nib body 602 contacts the rear end of the inner hole 67 of the first nib body 601, the fitting force acting between the second inclined surface 72 of the second nib body 602 and the rear end of the inner hole 67 of the first nib body 601 can be sufficiently reduced. In addition, by setting the angle θ2 to be less than 40 degrees, the outer diameter of the rear outer peripheral surface 75, that is, the maximum diameter of the nib body 60, can be reduced. Therefore, the enlargement of the nib body 60 can be suppressed. It is more preferred that the angle θ2 is greater than 20 degrees and less than 35 degrees. It is further preferred that the angle θ2 is greater than 25 degrees and less than 30 degrees.

[0122] The ballpoint pen tip 40 of this modified example is a ballpoint pen tip 40 having a ball 42 and a tip body 60 for holding the ball 42, wherein a first inclined surface 71 and a second inclined surface 72 arranged behind the first inclined surface 71 are provided on an outer peripheral surface 70 of the tip body 60, and in a cross section including the central axis A, the first inclined surface 71 extends linearly with respect to both the axial direction da and the radial direction dr in a manner inclined toward the outside of the radial direction dr as it goes toward the rear, and in a cross section including the central axis A, The second inclined surface 72 extends linearly with respect to both the axial direction da and the radial direction dr in a manner inclined toward the outside of the radial direction dr as it moves toward the rear, the rear end 71b of the first inclined surface 71 and the front end 72a of the second inclined surface 72 are connected to each other at the connecting portion 78, the angle θ2 between the second inclined surface 72 and the center axis A is greater than the angle θ1 between the first inclined surface 71 and the center axis A, and the outer diameter D1 of the connecting portion 78 is less than the inner diameter D3 of the inner hole 67 at the rear end 65a of the pen tip body 60.

[0123] The ballpoint pen refill 30 of this modified example includes the above-mentioned ballpoint pen tip 40 and an ink storage tube 35 for storing ink.

[0124] The ballpoint pen 10 of this modified example includes the above-mentioned ballpoint pen refill 30 .

[0125] According to the ballpoint pen tip 40, ballpoint pen refill 30, and ballpoint pen 10, when the front end of the second nib body 602 enters the inner hole 67 of the first nib body 601 from the rear, the first inclined surface 71 of the second nib body 602 can completely enter the inner hole 67 of the first nib body 601. In addition, the rear end 65a of the first nib body 601 can contact the connecting portion 78 or the second inclined surface 72 of the second nib body 602. Thus, damage to the first inclined surface 71 of the second nib body 602 can be effectively suppressed. In addition, the angle θ2 between the second inclined surface 72 and the central axis A is larger than the angle θ1 between the first inclined surface 71 and the central axis A, so that when the second inclined surface 72 of the second nib body 602 contacts the rear end of the inner hole 67 of the first nib body 601, the fitting force acting between the second inclined surface 72 of the second nib body 602 and the rear end of the inner hole 67 of the first nib body 601 becomes relatively small. As a result, the second nib body 602 is easy to fall off from the first nib body 601, and the second inclined surface 72 of the second nib body 602 is not easy to be damaged.

[0126] In the ballpoint pen tip 40 of the present modification, an angle θ1 between the first inclined surface 71 and the central axis A is greater than or equal to 4.0 degrees and less than or equal to 10 degrees.

[0127] According to such a ballpoint pen tip 40, when the angle θ1 is 4.0 degrees or more, in a state where the front end of the second nib body 602 enters the inner hole 67 of the first nib body 601 from the rear, when the central axis of the second nib body 602 is inclined relative to the central axis of the first nib body 601, it is possible to suppress the vicinity of the ball 42 of the second nib body 602 from contacting the inner hole 67 of the first nib body 601. Thus, it is possible to suppress damage to the ball 42 and the front end 63. Therefore, it is possible to suppress ink leakage from between the ball 42 and the front end 63 due to damage to the ball 42 and the front end 63. In addition, when the angle θ1 is 10 degrees or less, the outer diameter D1 of the connecting portion 78 can be reduced. Thus, the diameter of the nib body 60 becomes smaller near the front end of the nib body 60, and the writing surface such as paper becomes easier to visually confirm.

[0128] In the ballpoint pen tip 40 of the present modification, an angle θ2 between the second inclined surface 72 and the central axis A is greater than or equal to 18 degrees and less than or equal to 40 degrees.

[0129] According to such a ballpoint pen tip 40, when the second inclined surface 72 of the second nib body 602 contacts the rear end of the inner hole 67 of the first nib body 601, the fitting force acting between the second inclined surface 72 of the second nib body 602 and the rear end of the inner hole 67 of the first nib body 601 can be sufficiently reduced by making the angle θ2 18 degrees or more. In addition, when the angle θ2 is 40 degrees or less, the outer diameter of the rear outer peripheral surface 75, that is, the maximum diameter of the nib body 60, can be reduced. Therefore, the nib body 60 can be prevented from being enlarged.

[0130] Preferred embodiments of this modification are shown below.

[0131] [1] This variation provides a ballpoint pen tip having a ball and a nib body for holding the ball, wherein a first inclined surface and a second inclined surface arranged behind the first inclined surface are provided on the outer peripheral surface of the nib body, wherein in a cross section including a central axis, the first inclined surface extends linearly with respect to both the axial direction and the radial direction in a manner inclined toward the radially outer side as it goes toward the rear, and in a cross section including the central axis, the second inclined surface extends linearly with respect to both the axial direction and the radial direction in a manner inclined toward the radially outer side as it goes toward the rear, the rear end of the first inclined surface and the front end of the second inclined surface are connected to each other at a connecting portion, the angle θ2 between the second inclined surface and the central axis is greater than the angle θ1 between the first inclined surface and the central axis, and the outer diameter of the connecting portion is less than the inner diameter of the inner hole at the rear end of the nib body.

[0132] [2] The ballpoint pen tip according to [1], wherein an angle θ1 between the first inclined surface and the central axis is greater than or equal to 4.0 degrees and less than or equal to 10 degrees.

[0133] [3] The ballpoint pen tip according to [1] or [2], wherein an angle θ2 between the second inclined surface and the central axis is greater than or equal to 18 degrees and less than or equal to 40 degrees.

[0134] [4] This variation provides a ballpoint pen refill having: a ballpoint pen tip as described in any one of [1] to [3]; and an ink storage tube for storing ink.

[0135] [5] This variation provides a ballpoint pen, wherein the ballpoint pen has the ballpoint pen refill described in [4].

Claims

1. A ballpoint pen tip, comprising a ball and a tip body for holding the ball, wherein: A first inclined surface and a second inclined surface arranged behind the first inclined surface are provided on the outer peripheral surface of the pen tip body. In a cross section including the central axis, the first inclined surface extends linearly and inclined with respect to both the axial direction and the radial direction so as to be directed radially outward as it goes rearward. In a cross section including the central axis, the second inclined surface extends linearly and inclined with respect to both the axial direction and the radial direction so as to be directed radially outward as it goes rearward. The rear end of the first inclined surface and the front end of the second inclined surface are connected to each other. An angle θ2 between the second inclined surface and the central axis is greater than an angle θ1 between the first inclined surface and the central axis.

2. The ballpoint pen tip according to claim 1, wherein: A ratio L / L2 of a length L in the axial direction from the front end of the ball to the rear end of the first inclined surface to a length L2 in the axial direction of the second inclined surface is greater than or equal to 0.7 and less than or equal to 6.

3.

3. The ballpoint pen tip according to claim 1, wherein: A ratio L1 / L2 of a length L1 of the first inclined surface in the axial direction to a length L2 of the second inclined surface in the axial direction is greater than or equal to 0.4 and less than or equal to 4.

3.

4. The ballpoint pen tip according to claim 1, wherein: A length L in the axial direction from the front end of the ball to the rear end of the first inclined surface is greater than or equal to 1.25 mm and less than or equal to 2.5 mm.

5. The ballpoint pen tip according to claim 1, wherein: An angle θ1 between the first inclined surface and the central axis is greater than or equal to 4.0 degrees and less than or equal to 10 degrees.

6. The ballpoint pen tip according to claim 1, wherein: An angle θ2 between the second inclined surface and the central axis is greater than or equal to 18 degrees and less than or equal to 40 degrees.

7. The ballpoint pen tip according to claim 1, wherein: A ratio θ2 / θ1 of an angle θ2 between the second inclined surface and the central axis and an angle θ1 between the first inclined surface and the central axis is greater than or equal to 2.4 and less than or equal to 5.

5.

8. The ballpoint pen tip according to claim 1, wherein: An angle between the first inclined surface and the second inclined surface is greater than or equal to 146 degrees and less than or equal to 170 degrees.

9. A ballpoint pen refill, comprising: The ballpoint pen tip according to any one of claims 1 to 8; and The ink storage tube stores ink.

10. A ballpoint pen, wherein: This ballpoint pen has the ballpoint pen refill according to claim 9.

Images