JP2002067566A - Structure of pen point unit employing ball as writing medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the structure of a pen point part employing a ball as a writing medium, which is facilitated in arranging a coil spring having a straight part at the tip end thereof in a tip and capable of arranging the coil spring at a predetermined position. SOLUTION: The structure of pen point employing a ball as a writing medium is constituted of a ball, embraced rotably in the tip end of a tip, a ball seat having an ink flowing hole and a radial groove extended radially at the center of the same against which the ball is abutted, a coil spring, consisting of a coil wire material and having a straight part at the tap end thereof while abutting the straight part against the rear end of the ball through the ink flowing hole to push the ball against the tip end rim of the tip. In this case, a rounded part is formed on the tip end surface of straight part of the coil spring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a writing medium which is provided with a coil spring having a straight end portion for pressing a ball rotatably held in a tip against an inner wall surface of the tip end edge. Related to a pen tip structure.

[0002]

2. Description of the Related Art Conventionally, ballpoint pens and applicators in which an ink storage cylinder is directly filled with ink for a writing implement or a correction liquid are:
Many are provided by each manufacturer. Under these circumstances, in the pen tip structure using a ball in which ink or correction liquid having shear thinning viscosity is directly packed in the ink storage cylinder as a writing medium, the tip of the tip is vibrated or impacted with the tip facing downward, so that the tip of the tip is moved downward. Ink easily leaks. for that reason,
As a pen tip structure, when not in use, the ball held rotatably at the tip of the tip is brought into contact with the rear end of the ball by the coil spring having a straight part, and the inner wall surface of the tip tip edge There is a valve mechanism provided with a valve mechanism that presses the ink to make a gap between the tip end edge and the ball by the pressing force at the time of writing and allows ink to flow out.

[0003] In addition, it has been noted that a relatively small diameter ball having a diameter of 0.5 mm or less can be written in fine characters.
Ballpoint pens or applicators having a pen tip structure that rotatably hold a ball having a diameter of 0.5 mm or less are available on the market.

[0004]

The outer diameter of the coil spring provided in the chip is generally 1.0 mm to 3.0 mm.
The total length is very small, about 10.0 to 20.0 mm, and the coil springs must be arranged one by one in the chip, so that they can be easily arranged in the chip. Since it is necessary that the function of the valve structure composed of the ball and the inner wall surface of the tip end due to the pressing is sufficiently exerted, it is important to dispose it at a predetermined position.

The inventor of the present invention has studied a structure in which a coil spring is easily arranged in a tip in a pen tip portion structure using a ball having a coil spring having a straight portion as a writing medium. In the relationship between the ink circulation hole formed in the center part of the coil spring and the straight part of the coil spring, conventionally, the end face of the coil material has been cut, and when disposing the coil spring, the corner of the tip face of the straight part It has been found that burrs are caught on the inner surface of the chip, the coil spring cannot be arranged at a predetermined position, and the ball is not pressed. In particular, as the ball diameter becomes smaller, it is necessary to make the diameter of the ink circulation hole formed in the center of the ball seat smaller so that the ink corresponding to the smaller diameter flows out, but the smaller the ink circulation hole becomes, the smaller the diameter becomes. Since the gap between the straight portion of the coil spring and the ink flow hole is reduced, the corners and burrs of the end surface of the straight portion are easily brought into contact with the inner surface of the chip, and it is difficult to dispose the straight portion at a predetermined position. However, the smaller the wire diameter of the straight part of the coil spring, the greater the amount of movement of the runout in the ink circulation hole of the straight part of the arranged coil spring, and the tip surface of the straight part is the center of the ball. Does not always press the ball, the more the part to be pressed away from the center of the ball, the more insufficient the function of the valve structure composed of the ball and the tip inner wall surface by the pressing of the coil spring Problem arises.

[0006] The pressing force of the ball by the coil spring is determined from the set load of the spring. The set load of the spring differs depending on the wire diameter of the coil wire, the coil pitch, and the number of turns. If these are the same, the spring load is set based on the free length and the total length (mounting length) of the coil spring after the coil spring is provided. You. As the length obtained by subtracting the installation length from the free length becomes longer, the set load of the spring becomes larger, and naturally the pressing force of the ball also becomes larger. As described above, since the end face of the coil wire remains cut, the free length of the coil spring differs due to the corners and burrs of the end face of the straight portion, and the mounting length also differs. As a result, the set load of the spring changes, and the pressing force of the ball by the coil spring differs. Further, when the coil spring rear end is supported by a supporting member such as a chip rear end portion or a chip holder and is fixed so as not to move rearward, the coil member is formed by a corner portion or a burr of the rear end surface of the coil material. The different free lengths of the springs result in different mounting lengths. The pressing force of the ball by the coil spring is
If the pressing force of the ball is too small, the function of the valve structure composed of the ball and the inner wall of the tip end becomes insufficient, and if the pressing force of the ball is too large, the writing performance at a low load is poor, There is a problem that the ink discharge amount is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pen tip using a ball as a writing medium, in which a coil spring having a straight portion at a tip can be easily disposed in a tip and a coil spring can be disposed at a predetermined position. It is to provide a partial structure.

[0008]

According to the present invention, a ball is rotatably held at the tip of a chip, and the chip has an ink circulation hole and a radially extending radial groove communicating with the ink circulation hole in the center. Provided a ball seat against which the ball abuts,
A coil spring having a straight portion at the tip made of a coil wire is disposed with the straight portion contacting the rear end of the ball through the ink flow hole, and writing the ball by pressing the ball against the tip end edge. In the pen tip portion structure used as a medium, the tip end surface of the straight portion of the coil spring is rounded.

Further, the coil spring is supported by a support member at a rear end of the coil spring so as not to move rearward, and is provided at an outer corner of a rear end face of the coil wire at the rear end of the coil spring. , Rounded.

[0010] Still further, the roundness is formed by barrel polishing.

The coil wire in the present invention is, for example, a wire such as a stainless steel wire or a nickel-plated steel wire, which has been conventionally used for a pen tip structure using a ball as a writing medium.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. A pen tip portion structure 1 using a ball as a writing medium according to the present invention has Radially extending radial grooves 6 communicating with the ink circulation holes 4
A ball seat 5 having a diameter of 0.5 mm is provided in the ball holding chamber 3 so that a part of the ball 7 protrudes from the tip end edge 8 and is rotatably held.

In the tip member 2, a straight portion 1
0, the coil spring 9 and the straight portion 10
Are arranged in contact with the rear end of the ball 7 through the ink circulation hole 4 and are arranged so as to press the ball against the inner wall of the tip end edge 8. The coil spring 9 is formed on an inner wall of a chip holder 14 on which the chip member 2 is fitted, and is formed on a support portion (step portion) 14 for supporting the rear end 12 of the coil spring 9.
a and is fixed so as not to move backward.

The coil spring 9 is preliminarily barrel-polished (polishing time: 5 minutes, rotation speed: 180 rpm).
1a and the coil wire 9 at the rear end 12 of the coil spring
The outer corner 13a of the rear end face 13 is rounded. By forming the roundness on the tip end surface 11 of the straight portion, as shown in FIG.
When disposing the coil spring 9 in the chip 2, the coil spring 9 is less likely to be caught in the chip and is easily disposed. further,
Since the free length of the coil spring does not change due to the corners or burrs, the change in the set load of the spring is small, and the pressing force of the coil spring 9 on the ball 7 can be stably provided. Further, when the ball rotates, the ball does not come into contact with the corner portion 11a of the distal end surface 11 of the straight portion 10 of the coil spring, so that the ball rotates smoothly and the writing feel is good.

The rear end 12 of the coil spring is formed on the inner wall of the chip holder 14 by forming a rounded corner 13a outside the rear end face 13 of the coil wire. When supported by the supporting portion (step portion) 14a, the position of the coil spring rear end 12 does not deviate from a predetermined position due to burrs or the like.

In this embodiment, the corners 11a of the distal end face 11 of the coil wire and the outer corners 13a of the rear end face 13 of the coil wire are rounded by barrel polishing.
The method of forming the roundness is not limited to this, but barrel polishing is preferable because not only the corners 11a and 13a but also the entire coil spring can be polished. Also, the barrel polishing method is not limited to the above-described method, and may be appropriately selected and set depending on the material of the coil wire and the shape of the coil spring.

The method of supporting the rear end 12 of the coil spring is not limited to the method of supporting the rear end 12 of the coil spring on the stepped portion 14a formed on the inner wall of the chip holder. May be brought into contact with a portion where the rear end of the tip member 2 is reduced in diameter, or a coil spring having an ink flow passage at the rear end instead of reducing the rear end of the tip member 2 with a reduced diameter By press-fitting the support member, the chip member 2 may be prevented from falling off. In addition, in the ink container 15 into which the tip member 2 is directly fitted, a bead-shaped support portion projecting inward is formed on the inner wall surface of the ink container, and the rear end of the coil spring is supported by the support portion. It may be something.

The shape of the coil spring is not limited to the above-described embodiment, but may be any as long as it has a straight portion at least at the end.

[0019]

The pen tip structure using a ball as a writing medium according to the present invention has the above-described structure. Therefore, it is easy to dispose a coil spring having a straight portion at the tip in a tip, and at a predetermined position. A pen point structure using a ball as a writing medium, in which a coil spring can be provided, could be provided.

In addition, since the ball does not come into contact with the corners or burrs of the end face of the straight portion of the coil spring when the ball rotates, the ball can rotate smoothly and the writing feel can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a pen tip structure using a ball of the present invention as a writing medium.

FIG. 2 is an enlarged vertical sectional view of a main part in FIG.

FIG. 3 is an enlarged view of a coil spring in FIG.

FIG. 4 is an end view of a rear end of a coil spring.

FIG. 5 is a diagram showing a roundness forming process in barrel polishing of the tip end surface of the coil wire.

FIG. 6 is a diagram illustrating a roundness forming process in barrel polishing of the rear end surface of the coil wire.

[Explanation of symbols]

 1 Pen tip structure using ball as writing medium 2 Tip member 3 Ball holding chamber 4 Ink circulation hole 5 Ball seat 6 Ink circulation groove 7 Ball 8 Tip edge 9 Coil spring 10 Straight portion 11 Tip surface of coil wire 11a Tip Corner of surface 12 Rear end of coil spring 13 Rear end of coil wire 13a Outside corner

Claims (3)

[Claims] 1. A ball is rotatably held at the tip of a chip,
A coil spring having a ball seat on which the ball abuts, having a radially extending radial groove communicating with the ink flow hole and the ink flow hole in the center, and having a straight portion at the tip made of a coil wire, is provided in the chip. In a pen tip portion structure in which a straight portion is disposed in contact with the rear end of the ball through the ink circulation hole and the ball is pressed against the tip end edge, and the ball is used as a writing medium, A pen tip structure using a ball as a writing medium, characterized in that a straight portion has a rounded tip surface. 2. The coil spring is supported by a support member at a rear end of the coil spring so as not to move rearward, and a corner of a rear end of the coil spring outside a rear end face of the coil wire. 2. The pen tip structure using a ball as a writing medium according to claim 1, wherein the pen tip has a round shape. 3. A pen point structure using a ball as a writing medium according to claim 1, wherein the roundness is formed by barrel polishing.