JPH0852978A - Ball-point pen - Google Patents

Abstract

PURPOSE:To smoothly perform a handwriting having uniform density even when writing with low angle by a method wherein each of angle relationships of two fixing sections formed on a reduced diameter section in a tapered face of a ball-point pen tip, a diameter and a projection height of a ball and a distance relationship thereof with an opening secion of the tip are specified. CONSTITUTION:A ball-point pen tip A is so constituted that a reduced diameter section 2 is formed on a tip of a tapered face 1 and an ink passage 3 of an inner section thereof is opened to a ball holding chamber 7. A ball 8 is held in the ball holding chamber 7 and the ball 8 is projected from a tip opening section 10 of the reduced diameter section 2. In this case, equations of gamma+10 deg.<=beta<=gamma +40 deg. and beta10 deg.<=alpha<=beta+40 deg. are satisfied with respect to the reduced diameter while an angle of a first fixing section 2a in the tip side is designated as (alpha), an angle of a succeeding second fixing section 2b as (beta) and an angle of the tapered face 1 as (gamma). On the other hand, equations of 0.25D<=h<=0.35D and 0.007mm <=t<= 0.30mm are satisfied while a diameter of the ball 8 is designated as (D), a projection height as (h) and a distance between the ball 8 and tip opening section 10 as (t).

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、先端方向に向かって縮
径するテ−パ面の先端小口部を内方にかしめることによ
り縮径部を形成しインキ通路の一部であるボ−ル抱持部
に、筆記部材としてのボ−ルを前記開口部より一部突出
しつつ抱持してなるボ−ルペンチップに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bob which is a part of an ink passage, in which a tapered portion is formed by caulking inward a leading edge portion of a taper surface which is reduced in diameter toward the leading end. The present invention relates to a ball pen tip in which a ball as a writing member is held in the ball holding portion while partially protruding from the opening.

【０００２】[0002]

【従来の技術】従来よりボ−ルペンは、主に９０°乃至
５０°の範囲の筆記角度にて筆記できるように設計され
ている。しかし、アラビック文字や英文字を筆記する
際、通常より低い筆記角度で筆記することもあり、低筆
記角度でも明瞭な筆跡にて筆記可能なボ−ルペンが要望
されていた。2. Description of the Related Art Ball pens have hitherto been designed so that they can be written mainly at a writing angle in the range of 90 ° to 50 °. However, when writing Arabic characters or English letters, sometimes they are written at a writing angle lower than usual, and there has been a demand for a ball-point pen capable of writing with clear handwriting even at a low writing angle.

【０００３】[0003]

【発明が解決しようとする課題】低筆記角度で筆記する
ためは、ボ−ルペンチップの先端小口部分が紙などの被
筆記体にひっかからないことが必要である。そのために
は、低筆記角度にて筆記した場合にもボ−ル以外のボ−
ルペンチップの先端部分が被筆記面に接触しないように
すればよい。ボ−ルペンチップの先端部分が被筆記面に
接触しないようにするには、ボ−ル飛び出し防止をなす
縮径部のかしめ角度を小さい角度にしたり、ボ−ルペン
チップの先端部分の肉厚を薄くすることが考えられる。
しかし、先端部分の肉厚を薄くしたり先端小口部のかし
め角度を小さくしたものでボ−ルを抱持するために必要
な縮径量を得るためには、大きなかしめ角度にて加工す
る場合に比べて変形量の多い加工をしなくてはならな
い。すると、インキ通路のかしめ部分相当部である縮径
部の内面に悪影響を及ぼすと共に、小口の先端形状も不
均一になりやすく、被筆記面へのインキの均一な供給が
阻害されたり、ボ−ルの均一な回転が阻害されるなどし
て、筆跡に濃淡が発生してしまい、更に、小口の先端形
状が不均一になってしまったものでは、必要以上に先端
側に伸びた部分が形成されてしまい、低筆記角度で被筆
記面に当接し易いという問題があった。In order to write at a low writing angle, it is necessary that the tip edge portion of the ball-point pen tip is not scratched by a writing object such as paper. Therefore, even when writing at a low writing angle, a ball other than the ball is used.
It suffices that the tip of the rupen tip does not come into contact with the writing surface. In order to prevent the tip of the ball-pen tip from coming into contact with the writing surface, the caulking angle of the reduced diameter part that prevents the ball from jumping out should be set to a small angle or the tip of the ball-tip tip should be made thin. It is possible.
However, in order to obtain the necessary amount of diameter reduction to hold the ball by thinning the thickness of the tip part or reducing the caulking angle of the tip end part, when processing with a large caulking angle It has to be processed with a large amount of deformation compared to. This adversely affects the inner surface of the reduced diameter portion corresponding to the caulking portion of the ink passage, and the tip shape of the fore edge tends to be non-uniform, which hinders the uniform supply of ink to the writing surface. When the handwriting is shaded due to obstacles such as even rotation of the tool, and the tip shape of the forehead is uneven, a portion that extends beyond the tip side is formed more than necessary. Therefore, there is a problem in that it easily comes into contact with the writing surface at a low writing angle.

【０００４】[0004]

【課題を解決するための手段】本発明は、先端方向に向
かって縮径するテ−パ面の先端小口部を内方にかしめる
ことにより縮径部を形成しインキ通路の一部であるボ−
ル抱持部に、筆記部材としてのボ−ルを前記開口部より
一部突出しつつ抱持してなるボ−ルペンチップにおい
て、前記縮径部は、異なるかしめ角度を有する第１かし
め部及び第２かしめ部よりなり、先端小口側の第１かし
め部のかしめ角度をα、第２かしめ角度をβ、テ−パ面
の縮径角度をγとし、また、前記ボ−ルの径をＤ、前記
開口部より突出するボ−ルの出高さをｈとし、更に、前
記開口部における先端小口部の外形とボ−ルの外形との
距離をｔとしたとき、下記の（式５）乃至（式８）を満
足することを特徴とするボ−ルペンチップを要旨とす
る。According to the present invention, a reduced diameter portion is formed by caulking inwardly a leading edge portion of a taper surface that is reduced in diameter toward the leading end, and is a part of an ink passage. BO
In a ball pen tip in which a ball as a writing member is held in the ball holding portion while partially protruding from the opening, the reduced diameter portion has a first crimping portion and a second crimping portion having different crimping angles. The first crimping portion on the front edge side has a crimping angle of α, a second crimping angle of β, a taper surface reduction angle of γ, and the diameter of the ball is D Assuming that the height of the ball protruding from the opening is h, and the distance between the outer shape of the tip fore edge portion and the outer shape of the ball in the opening is t, the following (Equation 5) to (Equation 5) to (Equation 5) A gist of a ballpoint pen tip satisfying the expression (8).

【０００５】[0005]

【式５】０．２５Ｄ≦ｈ≦０．３５Ｄ[Formula 5] 0.25D ≦ h ≦ 0.35D

【０００６】[0006]

【式６】０．００７ｍｍ≦ｔ≦０．０３０ｍｍ[Formula 6] 0.007 mm ≤ t ≤ 0.030 mm

【０００７】[0007]

【式７】γ＋１０°≦β≦γ＋４０°[Formula 7] γ + 10 ° ≦ β ≦ γ + 40 °

【０００８】[0008]

【式８】β＋１０°≦α≦β＋４０°を要旨とする。[Formula 8] β + 10 ° ≦ α ≦ β + 40 ° is a gist.

【０００９】[0009]

【作用】低筆記角度にて筆記する場合にもボ−ルペンチ
ップの小口が被筆記面と当接しないようにするには、ボ
−ル出高さ（ｈ）、開口部における先端小口部の外形と
ボ−ルの外形との距離（ｔ）及びかしめ角度を調節して
やればよい。ボ−ルペンチップの少なくとも開口部にお
ける先端小口部が被筆記面と当接しないようなｔの長さ
は、筆記角度（θ）とボ−ルの径（Ｄ）とボ−ル出高さ
（ｈ）にて変わる。開口部における先端小口部の外形と
ボ−ルの外形との距離（ｔ）を、筆記角度（θ）とボ−
ルの径（Ｄ）とボ−ル出高さ（ｈ）で表すと下記の（式
９）になる。尚、ここでいう筆記角度（θ）とは、筆記
具の長手方向と被筆記面とが形成する角度の内、要望す
る最低の筆記角度である。In order to prevent the edge of the ball-point pen tip from coming into contact with the surface to be written even when writing at a low writing angle, the ball protrusion height (h) and the outer shape of the tip fore edge portion in the opening are provided. It suffices to adjust the distance (t) and the caulking angle between the ball and the outer shape of the ball. The length of t such that the tip edge portion of at least the opening of the ball-pen tip does not contact the writing surface is determined by the writing angle (θ), the diameter (D) of the ball, and the ball protrusion height (h). ) Changes. The distance (t) between the outer shape of the tip edge portion and the outer shape of the ball in the opening is defined by the writing angle (θ) and the ball.
The formula (9) below is expressed by the diameter (D) of the ball and the height (h) of the ball. The writing angle (θ) referred to here is the minimum desired writing angle among the angles formed by the longitudinal direction of the writing instrument and the writing surface.

【００１０】[0010]

【式９】 [Formula 9]

【００１１】しかし、ボ−ルペンチップの先端小口部を
かしめて縮径部を形成することは、ボ−ルの抜けを防止
するという意味の他に、ボ−ル抱持部の内壁にインキの
供給制御部分を形成するという意味がある。このインキ
の供給制御部分は、かしめ加工の押圧力を調節して、ボ
−ル抱持部の内壁とボ−ルとを当接させることにより、
ボ−ル抱持部の内壁の一部に平滑で且つボ−ルとのクリ
アランスが均一な部分を周設されるものである。この部
分は、ボ−ル表面へのインキの乗りを均一且つ容易に
し、ボ−ルに乗ったインキを均一に被筆記面に供給する
という役目を果たす（以下、このボ−ル抱持部の内壁に
周設される平滑で且つボ−ルとのクリアランスが均一な
部分をインキ制御部という）。つまり、インキ制御部を
周設することによって、筆記方向や筆記角度に極力影響
されない均一な濃度の筆跡を得ることができるものであ
る。本発明者らは、鋭意研究の結果、前記インキ制御部
の筆記方向や筆記角度に極力影響されない均一な濃度の
筆跡を得ることができる効果及びボ−ルペンチップの先
端部分の形状を均一に形成することは、ボ−ルペンチッ
プの先端小口部のかしめ角度に大きく影響されることを
見出し、低筆記角度での筆記においても被筆記面とひっ
かかりもなく濃淡の均一な美しい筆跡を得ることができ
るボ−ルペンチップを得たものである。However, in order to prevent the ball from slipping off by forming the reduced diameter portion by crimping the fore end portion of the ball pen tip, ink is supplied to the inner wall of the ball holding portion. It has the meaning of forming a control part. The ink supply control portion adjusts the pressing force of the caulking process to bring the inner wall of the ball holding portion into contact with the ball,
A part of the inner wall of the ball holding part is provided around a part which is smooth and has a uniform clearance with the ball. This portion serves to uniformly and easily apply the ink to the surface of the ball, and to uniformly supply the ink on the ball to the writing surface (hereinafter, this ball holding portion will be described later). A smooth portion surrounding the inner wall and having a uniform clearance with the ball is called an ink control section). That is, by surrounding the ink control unit, it is possible to obtain a handwriting with a uniform density that is not affected by the writing direction and the writing angle as much as possible. As a result of intensive studies, the inventors of the present invention have an effect of being able to obtain a handwriting with a uniform density that is not affected by the writing direction and the writing angle of the ink control section as much as possible, and form the shape of the tip portion of the ball pen tip uniformly. That is, it was found that the caulking angle of the tip fore edge of the ball-point pen tip is greatly affected, and even when writing at a low writing angle, it is possible to obtain a beautiful handwriting with uniform light and shade without getting caught on the writing surface. I got a rupen tip.

【００１２】[0012]

【実施例】以下、図面に基づいて一例について説明す
る。本発明のボ−ルペンチップＡの要部断面図である図
１に示すように、ボ−ルペンチップＡは、先端方向（図
面上方向）に向かって縮径するテ−パ面１を有し、この
テ−パ面１の先端を内方にかしめることにより縮径部２
を形成してある。ボ−ルペンチップＡの内部には、イン
キ通路３が連通孔として形成されており、インキ通路３
には、ボ−ル受け座部４ａを有する複数の内方突出部４
により縮径された中心孔５とインキ溝６とが形成され、
また、この内方突出部４により形成されるボ−ル抱持室
７に中心孔５とインキ溝６が開口している。ボ−ル８
は、ボ−ル抱持室７に、縮径部２にて飛び出し防止され
て抱持されていると共に先端部分を縮径部２の先端開口
部９より突出している。この先端開口部９よりボ−ル８
の突出する距離ｈがボ−ル出高さである。DESCRIPTION OF THE PREFERRED EMBODIMENTS An example will be described below with reference to the drawings. As shown in FIG. 1, which is a cross-sectional view of a main part of the ball-point pen tip A of the present invention, the ball-point pen tip A has a taper surface 1 whose diameter decreases in the tip direction (upward direction in the drawing). By crimping the tip of the taper surface 1 inward, the reduced diameter portion 2
Has been formed. The ink passage 3 is formed as a communication hole in the ball pen tip A.
Has a plurality of inward projections 4 having ball receiving seats 4a.
The central hole 5 and the ink groove 6 having a reduced diameter are formed by
Further, a center hole 5 and an ink groove 6 are opened in the ball holding chamber 7 formed by the inward protruding portion 4. Ball 8
Is held in the ball holding chamber 7 while being prevented from popping out by the diameter-reduced portion 2, and has its tip portion projected from the tip opening 9 of the diameter-reduced portion 2. Ball 8 from this tip opening 9
The protruding distance h is the height of the ball.

【００１３】前記縮径部２は、異なるかしめ角度を有す
る２種のかしめ部を有している。先端側の第１かしめ部
２ａ及びこの第１かしめ部２ａと連続する第２かしめ部
２ｂである。前記テ−パ面１のテ−パ角度（テ−パ面の
縮径角度）をγとし、第１かしめ部２ａのかしめ角度を
α、第２かしめ部２ｂのかしめ角度をβとした際、γ＋
１０°≦β≦γ＋４０°、β＋１０°≦α≦β＋４０°
となるようになしてある。実質的に、０°≦γ、α＜１
８０°であることより、２０°≦α＜１８０°、１０°
≦β＜１４０°、０°≦γ＜１００°となる。図示のボ
−ルペンチップＡは、α＝約８０°、β＝約５０°、γ
＝約３０°、ｈ＝約０．２００ｍｍ、Ｄ＝約０．７ｍ
ｍ、ｔ＝約０．０２０ｍｍのものを示してある。The reduced diameter portion 2 has two kinds of caulking portions having different caulking angles. The first caulking portion 2a on the tip side and the second caulking portion 2b continuous with the first caulking portion 2a. When the taper angle of the taper surface 1 (angle of reduction of the taper surface) is γ, the caulking angle of the first caulking portion 2a is α, and the caulking angle of the second caulking portion 2b is β, γ +
10 ° ≦ β ≦ γ + 40 °, β + 10 ° ≦ α ≦ β + 40 °
It is designed to be. Substantially 0 ° ≦ γ, α <1
Since it is 80 °, 20 ° ≦ α <180 °, 10 °
≦ β <140 °, 0 ° ≦ γ <100 °. The ball-pen tip A shown has α = about 80 °, β = about 50 °, γ
= About 30 °, h = about 0.200 mm, D = about 0.7 m
m, t = about 0.020 mm is shown.

【００１４】ボ−ル抱持室７の縮径部２相当部分である
インキ制御部１０は、かしめ加工の際、ボ−ル８に押し
つけられ周設される部分であり、平滑で且つボ−ルとの
クリアランスが均一な部分となっている。このインキ制
御部１０が平滑であることは、インキの移動を容易にす
ると共にインキのボ−ルへの乗りを容易にするものであ
る。また、インキ制御部１０がボ−ル８とのクリアラン
スが均一になっているということは、ボ−ルに乗り被筆
記面に吐出されるインキの量が均一になるということ
で、筆跡の濃淡や筆跡幅の均一性を良好になすものであ
る。The ink control portion 10, which corresponds to the reduced diameter portion 2 of the ball holding chamber 7, is a portion which is pressed around the ball 8 and is circumferentially provided at the time of caulking, and is smooth and has a ball shape. It has a uniform clearance with the cable. The smoothness of the ink control unit 10 facilitates the movement of the ink and also makes it easy to ride the ink on the ball. In addition, the fact that the ink control unit 10 has a uniform clearance with the ball 8 means that the amount of ink discharged onto the writing surface on the ball is uniform, which means that the density of the handwriting is different. It also provides good uniformity of handwriting width.

【００１５】ここで、かしめ角度とテ−パ面の縮径角度
α、β、γ及び開口部における先端小口部の外形とボ−
ルの外形との距離をｔとを種々の値に設定したボ−ルペ
ンチップを作成し、それぞれ作成したボ−ルペンチップ
に対し、筆記角度４０°における被筆記面に対するひっ
かかり（試験１）及び筆跡の濃淡の程度（試験２）につ
いて試験した。尚、ｔの値を種々設定した試験サンプル
については、α＝８０°、β＝５０°、γ＝３０°のサ
ンプルを作成し、試験１及び試験２を実施した。結果を
（表１）乃至（表１７）に示す。試験に使用したボ−ル
ペンチップは、テ−パ面の縮径角度が３０°のものと３
５°のものとを使用し、加工できなかったかしめ角度の
ものについては−にて示してある。Here, the caulking angle and the taper diameter reducing angles α, β, γ, and the outer shape and the shape of the tip fore end portion in the opening portion,
The ball pen tips with the distance t from the contour of the ball set to various values were created, and the ball pen tips created were caught on the writing surface at a writing angle of 40 ° (Test 1) and the density of the handwriting. (Test 2) was tested. As for the test samples in which the value of t was variously set, samples of α = 80 °, β = 50 °, γ = 30 ° were prepared, and the test 1 and the test 2 were performed. The results are shown in (Table 1) to (Table 17). The ball-pen tip used in the test had a taper surface with a diameter reduction angle of 30 °.
5 ° is used, and the caulking angle that cannot be processed is indicated by −.

【００１６】試験に使用したボ−ルペンチップの製造方
法としては、始めにボ−ルペンチップＡのテ−パ面１、
ボ−ル抱持室７、インキ通路３を切削加工などにより形
成する。インキ通路３は、内方突出部４を残すようにし
て中心孔５とインキ溝６と共に形成され、次いで、ボ−
ル抱持室７にボ−ル８を挿入する。このボ−ル８を抱持
するため、ボ−ルペンチップＡの先端の縮径部２を形成
するかしめ加工を施す。As a method of manufacturing the ball-pen tip used in the test, first, the taper surface 1 of the ball-pen tip A,
The ball holding chamber 7 and the ink passage 3 are formed by cutting or the like. The ink passage 3 is formed with the central hole 5 and the ink groove 6 so as to leave the inward protruding portion 4, and then the box
The ball 8 is inserted into the holding chamber 7. In order to hold the ball 8, the caulking process for forming the reduced diameter portion 2 at the tip of the ball pen tip A is performed.

【００１７】［試験１］ （筆記角度４０°における被
筆記面に対するひっかかり試験） 下記に示す試験条件にて筆記試験を行い、ボ−ルペンチ
ップと紙面とのひっかかりについて調べた。 評価 ○：ボ−ルペンチップと紙面との接触なし。 △：ボ−ルペンチップと紙面との接触があり、摩擦音の
発生が認められたが筆記はできた。 ×：ボ−ルペンチップが紙面をひっかき、均一な筆記線
が得られなかった。[Test 1] (Hooking test on writing surface at a writing angle of 40 °) A writing test was conducted under the following test conditions to examine the catching between the ball-pen tip and the paper surface. Evaluation ◯: No contact between the ball-pen tip and the paper surface. Δ: There was contact between the ball-pen tip and the paper surface, and generation of frictional noise was recognized, but writing was possible. X: The ball pen tip scratched the surface of the paper, and a uniform writing line was not obtained.

【００１８】［試験２］ （筆跡の濃淡の程度試験） 下記に示す試験条件にて筆記試験を行い、その筆跡の濃
淡の発生数を数えた。[Test 2] (Test of degree of shading of handwriting) A writing test was conducted under the test conditions shown below, and the number of shading of the handwriting was counted.

【００１９】試験条件 筆記角度：４０° 垂直筆記荷重：２００ｇ 筆記距離：１００ｍ 使用試験機：螺旋筆記試験機（Ｓｅｉｋｉ ＫＯＧＹＯ
ＬＡＢ製） 使用試験紙：ＮＳ５５記録用紙（（株）九菱科学機械製
作所製） 使用筆記具：ＢＫ１００（油性ボ−ルペン、ぺんてる
（株）製） チップ材質：フェライト系ステンレス チップ寸法：ボ−ル径０．７ｍｍ、ボ−ル出高さ０．２
００ｍｍTest conditions Writing angle: 40 ° Vertical writing load: 200 g Writing distance: 100 m Tester used: Spiral writing tester (Seiki KOGYO)
LAB) Test paper: NS55 recording paper (Kuryo Scientific Machinery Co., Ltd.) Writing instrument: BK100 (oil-based ballpoint pen, Pentel Co., Ltd.) Tip material: Ferrite stainless steel Tip size: Ball diameter 0.7mm, ball height 0.2
00 mm

【００２０】[0020]

【表１】 [Table 1]

【００２１】[0021]

【表２】 [Table 2]

【００２２】[0022]

【表３】 [Table 3]

【００２３】[0023]

【表４】 [Table 4]

【００２４】[0024]

【表５】 [Table 5]

【００２５】[0025]

【表６】 [Table 6]

【００２６】[0026]

【表７】 [Table 7]

【００２７】[0027]

【表８】 [Table 8]

【００２８】[0028]

【表９】 [Table 9]

【００２９】[0029]

【表１０】 [Table 10]

【００３０】[0030]

【表１１】 [Table 11]

【００３１】[0031]

【表１２】 [Table 12]

【００３２】[0032]

【表１３】 [Table 13]

【００３３】[0033]

【表１４】 [Table 14]

【００３４】[0034]

【表１５】 [Table 15]

【００３５】[0035]

【表１６】 [Table 16]

【００３６】[0036]

【表１７】 [Table 17]

【００３７】[0037]

【発明の効果】本発明のボ−ルペンチップは、低筆記角
度での筆記においても被筆記面とひっかかりもなく濃淡
の均一な美しい筆跡を得ることができるものである。The ball-point pen tip of the present invention is capable of obtaining beautiful handwriting with uniform shading even when writing at a low writing angle without being caught by the writing surface.

【図面の簡単な説明】[Brief description of drawings]

【図１】本発明の一例を示す要部断面図。FIG. 1 is a sectional view of an essential part showing an example of the present invention.

【符号の説明】[Explanation of symbols]

Ａ ボ−ルペンチップ １ テ−パ面 ２ 縮径部 ２ａ 第１かしめ部 ２ｂ 第２かしめ部 ３ インキ通路 ４ 内方突出部 ４ａ ボ−ル受け座部 ５ 中心孔 ６ インキ溝 ７ ボ−ル抱持室 ８ ボ−ル ９ 先端開口部 １０ インキ制御部 ｔ 先端小口部の外形とボ−ルの外形との距離 Ｄ ボ−ルの径 ｈ ボ−ル出高さ α 第１かしめ部のかしめ角度を β 第２かしめ部のかしめ角度を γ テ−パ面の縮径角度 A ball pen tip 1 taper surface 2 reduced diameter portion 2a first crimped portion 2b second crimped portion 3 ink passage 4 inward protruding portion 4a ball receiving seat portion 5 center hole 6 ink groove 7 ball embracing Chamber 8 Ball 9 Tip opening 10 Ink control section t Distance between tip outer shape and ball outer shape D Ball diameter h Ball protrusion height α First caulking angle β The crimping angle of the 2nd crimping part is γ The taper surface reducing angle

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】 先端方向に向かって縮径するテ−パ面の
先端小口部を内方にかしめることにより縮径部を形成し
インキ通路の一部であるボ−ル抱持部に、筆記部材とし
てのボ−ルを前記開口部より一部突出しつつ抱持してな
るボ−ルペンチップにおいて、前記縮径部は、異なるか
しめ角度を有する第１かしめ部及び第２かしめ部よりな
り、先端小口側の第１かしめ部のかしめ角度をα、第２
かしめ角度をβ、テ−パ面の縮径角度をγとし、また、
前記ボ−ルの径をＤ、前記開口部より突出するボ−ルの
出高さをｈとし、更に、前記開口部における先端小口部
の外形とボ−ルの外形との距離をｔとしたとき、下記の
（式１）乃至（式４）を満足することを特徴とするボ−
ルペンチップ。 【式１】０．２５Ｄ≦ｈ≦０．３５Ｄ 【式２】０．００７ｍｍ≦ｔ≦０．０３０ｍｍ 【式３】γ＋１０°≦β≦γ＋４０° 【式４】β＋１０°≦α≦β＋４０°1. A ball holding portion which is a part of an ink passage, wherein a reduced diameter portion is formed by caulking inward a leading edge portion of a taper surface which is reduced in diameter toward a leading end, In a ball-point pen tip that holds a ball as a writing member while partially projecting from the opening, the reduced diameter portion includes a first caulking portion and a second caulking portion having different caulking angles, and a tip end. The caulking angle of the first caulking portion on the edge side is α, the second
The crimping angle is β, the taper surface reducing angle is γ, and
The diameter of the ball was D, the protruding height of the ball protruding from the opening was h, and the distance between the outer shape of the tip end portion of the opening and the outer shape of the ball was t. In this case, the following features (Equation 1) to (Equation 4) are satisfied:
Rupen tip. [Formula 1] 0.25D ≦ h ≦ 0.35D [Formula 2] 0.007 mm ≦ t ≦ 0.030 mm [Formula 3] γ + 10 ° ≦ β ≦ γ + 40 ° [Formula 4] β + 10 ° ≦ α ≦ β + 40 °