JP2003170692A - Tip of ball-point pen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To smoothly discharge ink and to stabilize the standby position of a coil spring, in the tip of a ball-point pen having the coil spring arranged therein. <P>SOLUTION: The tip of the ball-point pen is constituted by holding a ball, which is partially exposed from the leading end of the tip, to a tip main body in a freely rotatable manner and fitting the ball in the tip so as to press the same to the inner wall surface of the leading end of the tip by the coil spring, which has a bulged part bulged from the outer diameter of a coil part and having a diameter larger than the inner diameter of the tip main body provided to its rear end, arranged to the rear of the ball. In this tip of the ball-point pen, a recessed holding part for holding the bulged part is formed to the rear end of the tip of the ball-point pen. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball-point pen tip in which a ball is constantly pressed against the inner wall surface of the tip of the tip by a coil spring.

[0002]

2. Description of the Related Art Conventionally, a ball pen tip having a valve mechanism in which a ball is constantly pressed against an inner wall surface of the tip end by a coil spring is known. Various shapes of such coil springs have been proposed or disclosed. JP-A No. 11-263093 “Pen tip portion using a ball as a writing medium” swells from the tip outer diameter to the rear end portion. A shape having a bulged portion is also disclosed, and in view of the increase in work efficiency and the number of production, the coil spring is automatically fed into the chip by using a component feeding device utilizing vibration. A coil spring shape suitable for assembly by an automatic assembly machine for assembly is disclosed.

Further, as a method of disposing a coil spring in the chip body, many proposals have been made such as caulking the rear end portion of the chip body inward or mounting a holding member in the rear end portion of the chip. There is.

[0004]

However, the inner diameter of the rear end portion of the ink, such as a step formed by caulking the rear end portion of the tip inward or by reducing the inner diameter of the rear end portion of the tip, is smaller than the inner diameter of the opening portion of the ink rear end. The holding portion of the coil spring has a problem that the ink flow path is obstructed and smooth ink discharge cannot be obtained. Also, at the stepped part formed by caulking the tip rear end part to the inside or reducing the inner diameter of the tip rear end part, variations occur in the standby position of the coil spring, resulting in an elastic force to press the ball. There were variations. Further, when the holding member is mounted in the rear end portion of the ball-point pen tip, air is likely to accumulate between the inner wall of the tip and the holding member, and this air may cause defective ink ejection and defective handwriting.

In view of the above problems, the present invention provides a ball-point pen tip in which a coil spring is provided in the tip, in which ink is discharged smoothly and the standby position of the coil spring is stable.

[0006]

In order to achieve the above object, in the present invention, a ball, a part of which protrudes from the tip of the chip, is rotatably held by the chip body and is arranged behind the ball. A coil spring having a bulged portion at the rear end portion that bulges out from the outer diameter of the coil portion and has a bulge portion that is larger than the inner diameter of the chip body, and is fitted so as to press the ball against the inner wall surface of the tip of the chip. -A rupen tip, in which a concave holding portion for holding the bulging portion is formed at a rear end portion of the ballpoint pen tip.

Further, the rear end portion of the tip body has a substantially conical shape whose diameter increases toward the rear end opening portion of the tip.

Further, the concave holding portion forms an inclined surface with the rear end side of the tip inclined.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. The ball-point pen tip 1 according to the first embodiment shown in FIGS. 1 and 2 includes a tip body 2 made of stainless steel, a ball 5 made of a tungsten carbide type cemented carbide material, and an ink flow passage 4. In the ball holding room I had,
By caulking the tip end 2a inside by caulking, a part of the ball 5 is rotatably held in a state where it is exposed to the outside of the tip end 2a.

Behind the ball 5, at the rear end portion of the coil portion 9, bulging out from the outer diameter of the coil portion 9, and the outer diameter L is larger than the inner diameter K of the rear end portion of the tip (L> K). A bar-shaped portion 8 is formed which forms a projecting portion 10 and which abuts the rear of the ball 5 at the tip.
The coil spring 7 formed with is formed by holding the bulging portion 10 in the concave holding portion 6 formed at the rear end portion of the chip. At this time, since the coil spring 7 is set to compress from the free length to the mounting length while the bulging portion 10 of the coil spring 7 is held by the concave holding portion 6, the coil spring 7 is elastically repelled. A force is generated, and by this elastic force, the rod-shaped portion 8 of the coil spring urges the ball 5 forward, and always abuts against the inner wall surface of the tip 2a of the tip. A valve mechanism may be provided to form a gap with the inner wall of the tip 2a.

When the bulging portion 10 is inserted into the rear end portion of the tip, the outer diameter L of the bulging portion is larger than the inner diameter K of the rear end portion of the tip, so that the tip body 2 and the coil spring 7 are in contact with each other. However, since the vicinity of the axial center of the bulging portion 10 of the coil spring 7 is hollow, if a certain pressing force is applied from the tip rear end opening 2b side, the bulging portion 10 bends inward,
When the bulging portion 10 reaches the concave holding portion 6 in the chip body, the bulging portion 10 returns to the original state from the inward bent state, and the concave holding portion 6
Can be held at. Since the standby position of the coil spring 7 is stabilized by holding it in the recessed holding portion 6, the pressing force of the ball is also stabilized in the same manner.

The ball-point pen tip 101 according to the second embodiment shown in FIG. 3 has an inner wall 103 at the rear end portion of the tip,
It is formed in a substantially conical shape whose diameter increases toward the tip rear end opening 102a. By doing so, the bulging portion 10 of the coil spring 7 collides with the inner wall 103 at the rear end of the chip, the bulging portion 10 bends inward, and the diameter gradually decreases, so that the concave holding portion. It becomes easy to load the battery into 106.

In the ball-point pen tip 201 according to the third embodiment shown in FIG. 4, the tip end side of the concave holding portion 206 formed in the tip body 202 is inclined to form the inclined surface 2.
It is as 03. Although the rear end of the bulging portion 10 is held by the inclined surface 203, it does not fall off due to the elastic force of the coil spring. Although not shown in the drawings, when the ballpoint pen tip of the present invention is used for a ballpoint pen using a low viscosity oil-based ink or an ink having a shear thinning property, a centrifugal step for discharging the air remaining in the tip is required. And Therefore, the chip rear end side 2 of the concave holding portion 206
It is preferable to incline 03 so that air can be easily discharged.

The ball-point pen tip of the present invention may have a structure in which a ball seat is provided to receive the writing pressure applied to the ball at the time of writing and to make the ball rotate smoothly. A structure without a seat may be used. Further, if the inner wall surface of the tip end is formed into a spherical shape having the same shape as the ball, the effect of the valve structure composed of the ball and the inner wall surface of the tip end can be improved. The shape and size of the channel groove may be appropriately selected and determined in consideration of the ink used and the amount of ink flowing out from the tip of the chip.

The above-mentioned chip body is usually obtained by cutting a rod-shaped stainless steel or the like, but it may be formed by drawing a tubular product or may be a resin molded product. Further, the method for forming the concave holding portion is to insert a cutting bite from the tip rear end opening, bring it into contact with the inner wall of the tip, and perform cutting while rotating while cutting or when the tip body is made of resin, injection molding, etc. There is no particular limitation.

Although not shown, the ballpoint pen tip of the present invention may be directly attached to the ink containing cylinder, the shaft cylinder or the like, or may be attached via a tip holder.

The method of loading the coil spring in the chip body is not particularly limited, but it can be carried out by an automatic assembling machine. For example, a coil spring is put into a component supply device that uses vibration, and the coil spring that has flowed to the outlet of the component supply device due to vibration is hung by hooking the bulging portion on the conveying member and then flowed to the coil spring loading port due to vibration. However, it can be loaded into the chip body from the rear end opening of the chip body.

[0018]

Since the present invention has the above-described structure, the inner diameter of the rear end portion of the tip is not reduced, so that ink outflow is not hindered and the standby position of the coil spring is stable. It was possible to provide a ballpoint pen tip with stable ball pressing force and smooth ink ejection.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a ball-point pen tip according to a first embodiment.

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

FIG. 3 is an enlarged vertical cross-sectional view of a main part showing a ball-point pen tip according to a second embodiment.

FIG. 4 is an enlarged vertical cross-sectional view of a main part showing a ball-point pen tip according to a third embodiment.

[Explanation of symbols]

1, 101, 201 Ballpoint pen tip 2, 102, 202 Chip body 2a, 102a, 202a Rear end opening 3 ball holding room 4 ink circulation holes 5 balls 6, 106, 206 holding part 7 coil spring 8 bar 9 Coil part 10 bulge 103 Chip rear end 203 inclined surface Inner diameter of K tip rear end L Outside diameter of bulge

Claims (3)

[Claims] 1. A ball, a part of which protrudes from the tip of the chip, is rotatably held in the chip body, and the ball is bulged from the outer diameter of the coil portion at the rear end of the ball, which is arranged behind the ball. A ball-pen tip having a ball spring fitted to the inner wall surface of the tip of the tip by a coil spring having a bulge portion larger than the inner diameter of the tip body, wherein the ball-tip tip has a rear end portion, A ball-point pen tip having a concave holding portion for holding the bulging portion. 2. The ball-point pen tip according to claim 1, wherein a rear end portion of the tip body has a substantially conical shape whose diameter increases toward the tip rear end opening. 3. The ball-point pen tip according to claim 1, wherein the concave holding portion forms an inclined surface in which the rear end side of the tip is inclined.