JP2005212304A - Ballpoint pen tip - Google Patents

Abstract

[Objective] To provide a ballpoint pen tip capable of obtaining a good writing without the occurrence of a line breaking phenomenon or a void phenomenon in which ink breaks during writing.
[Configuration] The diameter of the ball is A, the maximum diameter of the ball seat portion is B, and the diameter of the maximum inscribed circle that can be drawn on the cross section of the space formed between the plurality of formed inward projections is C The ratio of B to A (B / A) is 85.5% or more and 90.0% or less, and the ratio of C to B (C / B) is 60.3% or more and 75.0% or less. Is a ballpoint pen tip.
[Selection] Figure 1

Description

  It consists at least of a ball as a writing member and a ball holder that partially protrudes from the opening of the inner hole and rotatably holds the ball. A ballpoint pen tip that has a plurality of inward protrusions and that is caulked at least in the vicinity of the opening to form a portion having a diameter smaller than the diameter of the ball, thereby preventing the ball from falling off. The present invention relates to a structure in which a ball seat portion which is a concave having a curvature similar to the curvature of the ball is formed on the inward projection by being pressed against the projection.

  The ballpoint pen basically communicates with the ink stored in the ink tank inside the ballpoint pen tip, and when the ink attached to the ball moves while being pressed against the writing surface such as paper, it rotates. By transferring to the writing surface, handwriting is formed on the writing surface. However, not all of the ink adhering to the ball is transferred to the writing surface, and there are some inks that do not transfer to the writing surface, such as the ink corresponding to the side relatively to the rotation direction. Ink may adhere to and accumulate on the outside of the opening edge of the ball holder, and if it accumulates in a certain amount, it will fall on the writing surface, resulting in a problem of handwriting.

In Japanese Patent Application Laid-Open No. 09-169188, the gap portion between the opening of the ball holder and the ball is enlarged by forming the angle of the caulking portion to be 45 ° to 50 ° with respect to the axis of the ball holder. A ballpoint pen that has been solved and has good ink following ability is disclosed (see Patent Document 1). Japanese Patent Application Laid-Open No. 63-252799 discloses that a ball receiving portion is formed by pressing a ball against an inward projection after the ball is held in a small diameter near the opening of the ball holder to prevent it from coming off. A ballpoint pen is disclosed in which a relatively large gap is provided between the opening and the ball so that the ink that has not been transferred to the writing surface is returned to the ball holder to eliminate the stickiness. (See Patent Document 2).
JP 09-169188 A JP-A-63-252799

  When writing, the ball of the ballpoint pen tip is pushed in the direction opposite to the writing surface due to the reaction against the writing surface, and moves to a position greatly deviated from the center line in the longitudinal direction of the ball holder. It may end up. As a result, the gap between the ball holder and the opening on the opposite side of the writing surface of the ball holder and the ball is narrowed, and the narrowed gap when the ink that has not been transferred to the writing surface moves as the ball rotates It is difficult to be collected in the ball holder, adheres to and accumulates on the outside of the opening edge of the ball holder, and when it accumulates in a certain amount, it falls on the writing surface, and there is a problem in that handwriting occurs.

  By specifying the caulking angle as in the invention described in Patent Document 1, the gap between the opening of the ball holder and the ball is increased, or in the vicinity of the opening of the ball holder as in the invention described in Patent Document 2. Even when a ball receiving portion is formed by pressing the ball against the inward protrusion after caulking to a small diameter to prevent the ball from falling, even if a large gap is provided between the ball holder opening and the ball, If the ball has moved to a position greatly deviated from the longitudinal center line, it will not function, and this is insufficient to eliminate the handwriting blur.

  Further, as in the invention described in Patent Document 2, the inner protrusion is deformed by pushing the ball and the outer diameter portion of the seat that supports the relatively side portion of the ball is formed. When pushed in, the amount of deformation at the inward projection of the ball holder increases, and the number of portions that cause spring back without being completely plastically deformed increases. When the spring back increases, the difference between the shape of the ball seat and the shape of the ball increases, and at this time, a gap is formed between the ball seat and the corresponding ball. This gap is within a range that allows the ball to move in the radial direction, and the ball is likely to be displaced from the longitudinal center line of the ball holder.

  For these reasons, in the above-mentioned conventional technology, there has not yet been obtained what has been sufficiently eliminated, especially when the ballpoint pen tip is tilted and the ink is attached to the outside of the opening edge of the ball holder.・ Sometimes it accumulates, and when it accumulates in a certain amount, it sometimes falls on the writing surface and causes handwriting blur.

  As an improvement measure, the present invention includes at least a ball as a writing member and a ball holder that partially protrudes from the opening of the inner hole and rotatably holds the ball. A ballpoint pen tip that has a plurality of inwardly projecting portions radially and that forms a portion smaller than the diameter of the ball to prevent the ball from coming off, and has a plurality of inward projections radially In the case where a ball seat portion, which is a recess having a curvature similar to the curvature of the ball, is formed on the inward projection, a plurality of the ball diameters A and the maximum diameter of the ball seat portion are formed. When the diameter of the maximum inscribed circle that can be drawn on the cross section of the space formed between the inward protrusions is C, the ratio of B to A (B / A) is 85.5% or more, 90. 0% or less and B Against the ratio of C (C / B) 60.3% or more, which summarized as ballpoint pen tip is not more than 75.0%.

  By bringing the maximum diameter of the ball seat portion closer to the ball diameter, the ball is held at a position as far as possible from the longitudinal center line of the ball holder. By making the space between the inward protrusions including the center line in the longitudinal direction of the ball holder as large as possible, the amount of deformation when forming the ball seat can be reduced and the spring back is less, so the shape of the ball seat is the ball Thus, the movement restriction of the ball in the radial direction at the maximum diameter portion of the ball seat can be ensured. These enable the ball seat to hold the ball deeply during writing, so that a sufficient gap can be secured between the ball and the opening of the ball holder, even if the ballpoint pen tip is applied obliquely to the writing surface. Even if the ball receives a force for moving in the radial direction of the ball holder, the edge of the opening of the ball holder is difficult to wipe off the ink adhering to the ball.

  During writing, the ball seat gradually wears due to the rotation of the ball. Since the ball at the time of writing tends to shift outward from the center line in the longitudinal direction of the ball holder, the ball seat is worn from the outside. A gap is formed in the outer periphery of the ball seat due to wear. At this time, the contact position for holding the ball of the ball seat is inside the initial position (diameter). The ball seat was worn by making the inscribed circle that can be drawn in the cross section of the space formed by the portion close to the longitudinal center line side of the ball holder close to the maximum diameter portion (diameter) of the ball. Even if the ball is held at the inner periphery of the ball seat, the position close to the maximum diameter of the ball will be held, and the ball seat will hold the ball deeply. It is difficult to drop off, a gap between the ball and the opening of the ball holder can be secured, and the edge of the opening of the ball holder is difficult to wipe off the ink adhering to the ball.

  In addition, the portion formed on the circumference by several points near the center line in the longitudinal direction of the ball holder of each inward protrusion is the center when the ball is pressed to form the ball seat during processing. It plays a role of positioning. The ball formed in the space close to the center line in the longitudinal direction of the ball holder makes the inscribed circle that can be drawn in the cross section close to the maximum diameter (diameter) of the ball, thereby stabilizing the ball during processing. Can be positioned.

  As a specific example, the ratio of the maximum diameter of the ball seat portion to the ball diameter is 85.5% or more and 90.0% or less. The ratio of the diameter of the largest inscribed circle that can be drawn on the cross section of the space formed between the projecting parts is 60.3% to 75.0%, the inner diameter of the opening of the ball holder and the ball at the most advanced position. The difference from the cross-sectional diameter of the ball at the position corresponding to the opening when moved to is 0.005 mm or more and 0.040 mm or less. In addition, it is desirable for the ease of writing that the protruding amount of the ball from the ball holder is 20% to 40% of the ball diameter. The movement amount of the ball in the longitudinal direction in the longitudinal direction of the ball holder is preferably 0.5% to 3% of the ball diameter so as to create a gap in the opening. The thickness of the tip of the ball holder is preferably 1% to 5% of the ball diameter in order to prevent the tip from being caught on the writing surface during writing. In order to stabilize discharge, the maximum width of the radial groove is 5% to 30% of the ball diameter, and the circumscribed circle diameter formed by the radial groove is 95% to 105% of the ball diameter. desirable. Considering the ease of writing, the best diameter of the ball is 0.7 mm, the protruding amount of the ball from the ball holder is 0.20 mm, the tip wall thickness of the ball holder is 0.010 mm, and the radial groove has the maximum diameter. The diameter is 0.12mm, 5 places are installed in the circumference, and the circumscribed circle diameter of the radial groove is 0.69mm.

  In particular, in the case of ink having a low viscosity, in order to prevent leakage of ink from the tip of the ballpoint pen tip, sealing at the opening of the ball holder is required. In this case, the ball is urged forward by a resilient member such as a coil spring housed in the ballpoint pen tip and pressed against the inner surface of the opening of the ball holder to obtain a sealing property.

  An example will be described based on the drawings. What is shown in FIG. 1 is an enlarged vertical cross-sectional view of the main part of the ball-point pen tip, and FIG. 2 shows a cross-sectional view taken along the line X-X ′ of FIG. A ball holder 2 made of a metal such as stainless steel, brass, or white and white is rotatably held by a ball 1 made of cemented carbide or ceramics as a writing member. The ball holder 2 has a central hole 2 a as a penetrating coating liquid passage, and a tip portion of the central hole 2 a serves as a ball holding chamber 3 for holding the ball 1. The ball holding chamber 3 defines a range in which the ball 1 can be moved in the front-rear direction by a tip opening 3a having a reduced diameter by caulking and an inward projection 3b. Further, a ball receiving seat 3c having substantially the same curvature as that of the ball 1 is formed on the inward projecting portion 3b. The ball 1 is formed by being pressed and pressed from the tip side to be deformed, and the ball 1 is positioned on the ball seat 3c at the time of writing, and the ink ejection is stabilized to obtain a good handwriting. is there.

  Here, in the center hole 2a, in order from the rear (the lower side in FIG. 1), a rear hole 4, a middle hole 5 communicating with the rear hole 4 and the inward protrusion 3b, and an inward protrusion adjacent to the circumferential shape. A plurality of radial grooves 6 arranged between 3b and communicating with the ball holding chamber 3 are formed. Although the radial groove 6 in the illustrated example does not communicate with the rear hole 4, the radial groove 6 may penetrate and communicate with the rear hole 4. In the radial groove 6, the outermost portion is open toward the outer side than the portion where the ball 1 and the ball holding chamber 3 are in contact with each other. During writing, the ball 1 receives a writing load and moves backward, and the ball 1 comes into contact with the inward projection 3b by the backward movement, but the ink flow path is not blocked by the radial groove 6, and the ball holding chamber 3 Ink 7 is supplied inside.

  A method for forming the ball seat 3c will be described. FIG. 3 shows the ball 1 inserted into the ball holding chamber 3 before the ball seat is formed. The ball holding chamber 3, the middle hole 5, and the rear hole 4 are each processed by a cutting blade, and the radial grooves 6 are formed by broaching.

  As shown in FIG. 4 from the state shown in FIG. 3, the ball receiving pin 3 is formed by impacting the ball 1 with the ball pressing pin P to deform the inward protruding portion 3b. The length of the diameter φB of 3c (see FIG. 2) is adjusted by the depth at which the ball pressing pin P is driven.

  The caulking process of the tip opening of the ball holder 2 will be described with reference to FIG. In the caulking process, a plurality of caulking rollers Q are rotated and pressed against the outer wall of the tip opening of the ball holder 2 so that the inner diameter of the opening is smaller than the diameter of the ball 1. At this time, a caulking taper portion 2 b is formed on the outer wall portion of the ball holder 2. In a ball-point pen tip that sets a large amount of ink to be discharged, such as water-based ink, it is effective to form the caulking taper portion 2b in the longitudinal direction of the ball holder 2 on the tip side from the center position of the ball 1, but oil-based ink In the ball-point pen tip that suppresses the discharge, the discharge can be optimized by forming the caulking taper portion 2 b from the front end side in the longitudinal direction of the ball holder 2 to the rear side from the center position of the ball 1.

  Further, after the caulking process shown in FIG. 5, the concave outer surface caulking roller R is pressed against the front end portion of the ball holder 2 as shown in FIG. Form into shape. This is to prevent the ball holder 2 from being caught when the outer periphery of the ball holder 2 hits the writing surface, and it may not be necessary depending on the type of ink and the desired writing environment. Also good. Further, the caulking process and the convex curve caulking process described above may be performed simultaneously with a roller in one process.

  FIG. 7 shows a ball push-up process for providing a space between the ball 1 and the tip opening 3a. After the above-described caulking process, the push-up pin S is inserted from the rear end side of the ball holder 2 and the rear end side of the ball 1 is pushed up. At this time, the ball 1 is pushed up to the extent that it does not jump out. The inner diameter of the tip opening 3a of the ball holder 2 is increased by this process, but the ball is prevented from coming off by making it smaller than the diameter of the ball 1. Although not shown, in order to prevent the ball 1 from jumping out in this step, a stopper that obstructs the movement of the ball in the tip direction may be installed on the tip side of the ball 1 for processing. As a result, a gap 2c is formed at a portion corresponding to the same position of the ball 1 as the inner diameter of the tip opening 3a.

FIG. 8 shows an arrow view when the ball 1 is moved to the most advanced position after the pushing-up process. FIG. 8 is a view corresponding to the view taken along the line ZZ ′ in FIG. 7, but for the sake of convenience of explanation, the size of the gap space (ie, φD−φE) between the ball 1 and the ball holder 2 is exaggerated. Even when the ball 1 is moved to the foremost position, a gap 2 c is provided between the ball holder 2 and the tip of the ball holder 2.
The gap 2c is represented by the difference between the tip opening inner diameter φD of the ball holder 2 and the cross-sectional diameter φE of the ball 1 corresponding to the position. The gap 2c is used to make it easier for ink 7 attached to the ball 1 that has not been transferred to the writing surface to be collected when the ball 1 is re-contained in the ball holder 2 as the ball 1 rotates. It is. This suppresses writing during writing.

An example of the form of the writing instrument is shown in FIG. A ball-point pen tip 8 constituted by a ball holder 2 holding a ball 1 as a writing member in a state where a part of the ball 1 protrudes is directly connected to an ink containing portion 9 at a rear portion thereof. In addition, between the ink accommodating part 9 and the ball-point pen tip 8, if necessary for adjusting the difference in diameter, one or more connecting parts may be interposed. In this example, the ink container 9 is assumed to be a cylinder made of polypropylene by extrusion molding. When a refill consisting of a ballpoint pen tip 8, an ink container 9 and an ink 7 is installed in the outer body (not shown), and when the ink 7 runs out and writing becomes impossible If the refill is replaced, it can be used as a writing instrument. It is appropriate to configure the exterior body with a plurality of parts made of various materials, to protect the pen tip with a cap, or to allow the pen tip to move in and out by pressing the rear end of the writing instrument. Further, the ink container 9 does not need to be provided with an exterior body as long as it holds itself.
In this example, it is assumed that a polypropylene resin is used as a material for forming the ink containing portion 9, but a polyamide resin, a polybutylene terephthalate, a polybutylene naphthalate, a polyethylene naphthalate, a vinyl chloride resin, and an ethylene vinyl alcohol are used. Other resins such as a polymer, polyacrylonitrile, fluororesin, polyacetal resin, polyethylene, polyethylene terephthalate, polycarbonate resin, polystyrene resin, ABS resin, and metals such as stainless steel may be used. Even if a member (not shown) for preventing leakage of the ink 7 is installed at the rear portion of the ink 7 in the ink containing portion 9 or a follower body (not shown) that moves forward as the ink 7 decreases is installed. good. The shape of the ink containing portion 9 may be a bottomed cylindrical container instead of a cylindrical body.

  Ball diameter (φA), ball seat diameter (φB), inner diameter of the ball seat formed at the tip of each inward protrusion (φC), inner diameter of the tip opening of the ball holder (φD), the ball at the most advanced position The ball pen tip having various dimensions in the ball cross-sectional diameter (φE) of the portion located at the tip of the ball holder when it is made into a refill form shown in FIG. 9 (“Lorry” manufactured by Pentel Co., Ltd.) , Product code: the same structure as BP107-A), an assembly writing test sample was prepared. The writing line written by this writing test sample was evaluated.

In the writing test, each test sample described above was used, a 200 m writing test was performed by an automatic writing machine, and the handwriting between 100 m and 200 m was evaluated. As for the writing conditions by the automatic writing machine, writing was performed in a spiral shape using a writing paper described in JIS S6054, a writing angle of 70 °, a writing load of 150 g, a writing speed of 7 cm / sec. The following are examples of handwriting state defects.
Defective: Ink that has adhered and deposited on the outside of the opening edge of the ball holder fell on the writing surface, resulting in excess ink on the handwriting.
Line cracking failure: A portion where no handwriting is formed near the center of the width of the handwriting.
Poor faintness: The handwriting is interrupted in the middle. The part where the handwriting is not formed is generated.
The results are shown in Table 1.
A, B, C, D, and E in Table 1 indicate the length of each part shown in FIGS. 1, 2, and 8, and the unit is mm (millimeter). The difference between φD, which is the inner diameter of the opening of the ball holder 1, and φE, which is the cross-sectional diameter of the ball at the position corresponding to the opening when the ball 2 is moved to the foremost position, is shown as DE. The ink used for the test was the black ink used in “Lorry” (product code: BP107-A) manufactured by Pentel Co., Ltd.

  The present invention can be used for ballpoint pens such as oil-based inks and water-based inks, applicators such as glues and correction liquids, and cosmetics such as nail colors, lip colors, and eyeliners. Depending on the type of ink or coating solution, the inside of the ink containing portion may be pressurized or may be directly or indirectly pressed to provide ejection support. If the ink has a high drying property, a cap can be provided to prevent drying, or the opening of the ball holder can be covered with an elastic member. When the ink viscosity is low, fluidity is high, or when the above-mentioned ejection support is provided, the ball can be pressed against the tip side by at least the elastic member installed in the ball holder to seal the opening with the ball You may do it.

The principal part longitudinal cross-sectional view which shows an example of a ball-point pen tip. FIG. 2 is a cross-sectional view taken along the line x-x ′ of FIG. 1. The principal part longitudinal cross-sectional view which shows the middle of the process of a ball-point pen tip. The principal part longitudinal cross-sectional view which shows the processing method of a ball-point pen tip. The principal part enlarged view which shows the crimping process of a ball-point pen tip. The principal part enlarged view which shows the curved surface crimping process of a ball-point pen tip. The principal part longitudinal cross-sectional view which shows the pushing-up process of a ball | bowl. Arrow view when the ball is placed at the most advanced position. The longitudinal cross-sectional view which shows an example of a ball-point pen refill.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ball 2 Ball holder 2a Center hole 2b Caulking taper part 2c Clearance 3 Ball holding chamber 3a End opening part 3b Inward protrusion part 3c Ball seat 4 Back hole 5 Medium hole 6 Radial groove 7 Ink 8 Ball-point pen tip 9 Ink accommodating part A Ball diameter B Ball seat diameter C Diameter of the maximum inscribed circle that can be drawn on the cross section of the space formed between the inward protrusions D Inner diameter of the tip of the ball holder E Move the ball to the most advanced position Of the ball at the position corresponding to the tip of the ball holder

Claims (2)

It consists at least of a ball as a writing member and a ball holder that partially protrudes from the opening of the inner hole and rotatably holds the ball. A ballpoint pen tip that has a plurality of inward protrusions and that is caulked at least in the vicinity of the opening to form a portion having a diameter smaller than the diameter of the ball to prevent the ball from falling off. In which a ball seat portion that is a dent of curvature similar to the curvature of the ball is formed, the diameter of the ball is A, the maximum diameter of the ball seat portion is B, and a plurality of inward projections are formed between When the diameter of the maximum inscribed circle that can be drawn on the cross section of the formed space is C, the ratio of B to A (B / A) is 85.5% or more and 90.0% or less, and the ratio of C to B Ratio (C / B) At least 0.3%, or less 75.0% ballpoint pen tip. The difference between the inner diameter of the opening of the ball holder and the cross-sectional diameter of the ball at a position corresponding to the opening when the ball is moved to the foremost position is 0.005 mm or more and 0.040 mm or less. Ballpoint pen tip as described in

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