JP2010069617A - Ball-point pen tip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball-point pen tip wherein the writing ball is located in the immediate proximity to the inner surface of the ball-point pen tip when it is not used, and a pressing force is given to the approximate center of the writing ball, the rod shank of the coil spring not closing off the radial grooves. <P>SOLUTION: The ball-point pen tip includes: a small ball provided behind the writing ball in a rotatable manner whose diameter is smaller than the diameter of the writing ball and the diameter of the ink flow hole; a valve operating mechanism wherein the coil spring presses the small ball toward the tip end and thereby the writing ball goes in the immediate proximity to the inner wall of the tip end; and a build-up part formed in the ink flow hole which extends toward the axial center of the ball-point pen tip in a build-up manner, the contact part between the small ball and the coil spring being characteristically located closer to the rear end of the tip than to the radial groove. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention has an ink circulation hole formed in the center of the bottom wall of the ball holding chamber and a radial groove extending radially from the ink circulation hole in the chip body, and a writing ball is inserted into the bottom wall. The present invention relates to a ball-point pen tip that is configured to hold a tip of a writing ball inwardly so that a part of a writing ball protrudes from the tip of the tip and is rotatably held.

  A coil spring is disposed at the rear end of the ball, and the ball is brought into intimate contact with the inner wall surface of the tip of the tip by the pressing force of the coil spring, and a gap is formed between the ball and the inner wall of the tip of the tip by writing pressure during writing. A ball-point pen tip having a valve mechanism for forming a pin is well known, and Japanese Patent Application Laid-Open No. 2000-158869 “Ball-point pen tip” describes that even if the rod shaft portion of a coil spring moves, the rod shaft portion has a radial groove. A structure that does not close is disclosed.

  Also, in a ballpoint pen tip having a valve mechanism at the tip end, Japanese Patent Application Laid-Open No. 2006-198835 “Ballpoint Pen Tip” discloses a tip end ball in order to prevent problems such as poor writing due to burrs in the rod shaft portion of the coil spring. It is disclosed that a contact ball is disposed at the rear end, and the contact ball is pressed against the tip ball by a coil spring.

By the way, the ball-point pen tip provided with the valve mechanism is intended to bring the ball into close contact with the inner wall surface of the tip end of the tip, but the pressing force to the ball gives the pressing force to the center of the ball, It becomes easy to bring the ball into close contact with the inner wall surface of the tip of the chip without tilting the ball.
"JP 2000-158869 A" "Japanese Patent Laid-Open No. 2006-198835"

  However, in Patent Document 1, the coil spring has a very small wire diameter of φ0.1 mm to φ0.3 mm, and it is very difficult to form a plurality of through grooves in the rod shaft portion. In addition, forming a through-groove smaller than the outer diameter of the rod shaft portion at the rear end of the center hole increases the number of manufacturing steps, resulting in a problem of increased manufacturing costs.

  Further, in Patent Document 2, there is a problem that the rod shaft portion of the coil spring moves and deviates from the center of the contact ball, and as a result, the contact ball does not press the center of the writing ball, or There is a problem that the rod shaft portion closes the radial groove.

  In view of the above problems, the present invention can provide a pressing force to a substantially center of a writing ball in a ball-point pen tip in which the writing ball is in close contact with the inner wall surface of the tip end when not in use. The shaft portion provides a ball-point pen tip that does not close the radial groove.

  In order to achieve the above object, in the present invention, the chip body has an ink circulation hole formed in the center of the bottom wall of the ball holding chamber, and a radial groove extending radially from the ink circulation hole. In the ballpoint pen tip which is inserted into the wall and the tip end of the tip is caulked inward so that a part of the tipping ball protrudes from the tip end and is held freely. A small-diameter ball smaller than the diameter of the writing ball and the ink circulation hole diameter is rotatably disposed behind the ball, and the small-diameter ball is pressed toward the tip end portion side by a coil spring, and the small-diameter ball is When having a valve mechanism for bringing the writing ball into close contact with the inner wall of the tip end of the chip, and forming a build-up portion extending in the form of a build-up on the axial center side of the ball-point pen tip in the ink circulation hole. Moni, contact portion between the small-diameter ball and a coil spring, characterized in that located on the tip end side than the radial grooves.

  Further, the hardness of the small-diameter ball is lower than the hardness of the writing ball.

  Furthermore, a movement restricting means for restricting movement of the small-diameter ball on the chip rear end side is provided on the chip rear end side of the small-diameter ball.

  In the ballpoint pen tip in which the writing ball is in close contact with the inner wall surface of the tip of the tip when not in use, the pressing force can be applied to the approximate center of the writing ball, and the coil spring closes the radial groove. We were able to provide a ballpoint pen tip that would never be done.

Example 1
Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the ball-point pen tip of the present invention is not limited to the embodiments. In the drawings, the same members and parts are denoted by the same reference numerals.

  The ball-point pen tip 1 shown in FIGS. 1 to 3 first extends in the tip body 2 in the center of the bottom wall 4 of the ball holding chamber 3 in a radial manner communicating with the ink circulation hole 6 and the ink circulation hole 6. Radial grooves 8 are formed. Thereafter, the writing ball 10 is placed on the bottom wall 4, the ball seat 5 having substantially the same shape as the writing ball 10 is provided by hammering, and the tip end portion 2 a is caulked inward, whereby the writing ball 10 It is rotatably held so that a part protrudes from the tip end portion 2a. Further, a built-up portion 9 is formed at the joint between the rear end face of the radial groove 8 and the ink circulation hole 6 so as to extend on the axis J side of the ball-point pen tip.

  A small-diameter ball 11 is rotatably disposed behind the writing ball 10 and has a rod shaft portion 12a at the tip thereof for pressing the small-diameter ball 11 toward the tip tip portion 2a. A coil spring 12 is provided. At this time, the contact portion S between the small-diameter ball 11 and the rod shaft portion 12a of the coil spring is located on the chip rear end side with respect to the radial groove 8.

  A movement restricting member 13 is fitted in the rear hole 7 as a movement restricting means for preventing the small-diameter ball 11 from moving backward. The movement restricting member 13 is provided with a through hole 13a whose tip side is smaller than the diameter of the small diameter ball 11 and a through hole 13b through which ink flows. The passage hole 13a is formed so as to gradually decrease in diameter from the rear end side toward the front end side so that the rod shaft portion 12a of the coil spring 12 is restricted from moving toward the axis J.

  When the writing ball 10 is not in use, the writing ball 10 is in close contact with the inner wall surface of the tip end 2a by the pressing force of the coil spring 12 via the small-diameter ball 11, and the writing ball 10 and the chip are applied by the writing pressure at the time of writing. A gap mechanism is formed in the inner wall of the front end portion 2a to form a valve mechanism that allows ink to flow out to the paper surface.

  In the present invention, a built-up portion 9 is formed at the junction between the rear end face of the radial groove 8 and the ink circulation hole 6 so as to be built up on the axis J side of the ball-point pen tip. Therefore, even if the small-diameter ball 11 comes into contact with the built-up portion 9, the small-diameter ball 11 moves to the axis J side while rotating, and a pressing force can be applied to the center of the writing ball 10. it can.

  The writing ball 10 is a carbide ball of φ0.7 mm, hardness 1600 Hv, tungsten carbide, and the small-diameter ball 11 is a stainless steel ball of φ0.35 mm, hardness 800 Hv. Moreover, the wire diameter of the coil spring 12 was 0.15 mm, and the diameter of the ink circulation hole 6 was φ0.45 mm.

  The flow of ink for the ballpoint pen from the ink storage cylinder (not shown) to the writing ball 10 is first from the ink storage cylinder through the communication hole 13a and the through hole 13b of the movement restricting member 13 to the rear hole 7 and the ink circulation hole 6. The small diameter ball 11 flows. Thereafter, the writing ball 10 is reached through the radial grooves 8 and the gaps between the small-diameter balls 11 and the ink circulation holes 6. Since the ink reaches the writing ball 10 as described above, it is not necessary to newly form a groove or the like through which the ink flows, and an increase in the manufacturing process can be suppressed.

  The material of the writing ball 10 and the small diameter ball 11 is not particularly limited. However, by reducing the hardness of the small-diameter ball 11 with respect to the writing ball 10, the writing ball 10 is hardly damaged when writing with high writing pressure, and writing defects such as line breakage do not occur most. preferable. Specifically, it is desirable that the hardness of the writing ball 10 is at least twice that of the small-diameter ball 11.

  Moreover, it is preferable that the arithmetic average roughness (Ra) of the surface of the small-diameter ball 11 is smaller than the arithmetic average roughness (Ra) of the surface of the writing ball 10. If the arithmetic average roughness (Ra) of the surface of the small-diameter ball 11 is larger than the arithmetic average roughness (Ra) of the surface of the writing ball 10, there is a concern that the writing ball 10 may be adversely affected. This is because it causes writing defects such as jumping. The arithmetic average roughness (Ra) of the small-diameter ball 11 is desirably 5 nm or less.

  Further, the diameter of the small-diameter ball 11 and the diameter of the ink circulation hole 6 are not particularly limited, but the smaller the difference between the diameter of the small-diameter ball 11 and the diameter of the ink circulation hole 6 is, the more the center of the writing ball 10 is pressed. However, if the diameter of the small-diameter ball 11 is less than 50% of the diameter of the ink circulation hole 6, the rod shaft portion 12a may enter between the small-diameter ball 11 and the ink circulation hole 6. If it exceeds 80% of the 6 diameters of the flow holes, the ink followability deteriorates, so that it is 50% to 80%, more preferably 60% to 70%.

  Further, the size of the built-up portion 9 is not particularly limited, but the smaller the inscribed circle diameter of the built-up portion 9 is preferable because the small-diameter ball 11 can easily press the center of the writing ball 10, and the meat Most preferably, the inscribed circle diameter of the raised portion 9 is smaller than the diameter of the small-diameter ball 11.

  Further, the movement restricting member 13 provided in the rear hole 7 can be provided as appropriate, but by providing a movement restricting means for restricting the movement of the small-diameter ball 11 toward the tip rear end side, the rear-end side of the small-diameter ball 11 is provided. This is preferable because the assemblability is improved without fear of falling off the rod, and the rod shaft portion 12a of the coil spring 12 passing through the passage hole 13a of the movement regulating member 13 is regulated to move toward the axial center. In the present embodiment, for convenience, the movement restricting member 13 different from the chip body is provided as the movement restricting means. However, a built-up movement restricting portion may be provided integrally with the chip body.

  In this embodiment, for convenience, the coil spring 12 having the rod shaft portion 12a at the tip is used, but a structure having no rod shaft portion may be used. However, since the coil spring 12 having the rod shaft portion 12a easily closes the radial groove 8, the effect of the present invention is remarkable.

  Further, in this embodiment, for the sake of convenience, a built-up portion 9 is formed at the joint between the rear end face of the radial groove 8 and the ink circulation hole 6 so as to extend on the axis J side of the ball-point pen tip. If there is a valve mechanism for bringing the writing ball 10 into close contact with the inner wall of the tip end portion via the small-diameter ball 11 by the pressing force of the spring 12, the formation position of the built-up portion 9 is the same as the ball seat 5 and the ink circulation. It can form, without being specifically limited to the ink distribution | circulation hole 6, such as the junction part of the hole 6. FIG. However, in the joint portion between the radial groove 8 and the ink circulation hole 6, the portion generated when the radial groove 8 is formed can be a buildup portion 9, and the buildup portion 9 can be formed simultaneously with the formation of the radial groove 8. This is most preferable because it does not increase the number of manufacturing steps.

  In this embodiment, the ball seat 5 is formed on the bottom wall 4 of the ball holding chamber 3 for the sake of convenience. However, a ballpoint pen tip that does not form the ball seat may be used.

  The ball-point pen tip of the present invention can be widely used as a ball-point pen tip without being limited to the kind of ink, such as ink imparted with water, oiliness, and shear thinning viscosity.

FIG. 3 is a longitudinal sectional view of a main part of the ballpoint pen chip in Example 1 with a part thereof omitted. FIG. 2 is an enlarged vertical cross-sectional view of a main part, partly omitted in FIG. 1. It is an AA cross-sectional arrow view before ball seat formation in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ball-point pen tip 2 Tip body 2a Tip part 3 Ball holding chamber 4 Bottom wall 5 Ball seat 6 Ink flow hole 7 Rear hole 8 Radial groove 9 Overlaying part 10 Writing ball 11 Small-diameter ball 12 Coil spring 12a Bar shaft part 13 Movement Regulatory member

Claims (3)

The chip body has an ink circulation hole formed in the center of the bottom wall of the ball holding chamber, and a radial groove extending radially from the ink circulation hole, and a writing ball is inserted into the bottom wall. In the ball-point pen tip formed by caulking the tip end inward so that a part of the ball for writing protrudes from the tip end of the tip and is rotatably held, the diameter of the ball for writing is placed behind the ball for writing. And a small-diameter ball smaller than the ink circulation hole diameter is rotatably arranged, the small-diameter ball is pressed against the tip end portion side by a coil spring, and the writing ball is placed on the inner wall of the tip end portion by the small-diameter ball. In addition to providing a close valve mechanism, the ink circulation hole is formed with a built-up portion extending on the axial center side of the ballpoint pen tip, and the small-diameter ball and coil spring are formed. Ballpoint pen tip contact portion with the grayed, characterized in that located on the tip end side than the radial grooves. The ballpoint pen tip according to claim 1, wherein the hardness of the small-diameter ball is lower than the hardness of the writing ball. 3. The ballpoint pen tip according to claim 1, wherein a movement restricting unit that restricts the movement of the small-diameter ball on the chip rear end side is provided closer to the chip rear end than the small-diameter ball.

Images