JP2012179751A - Ballpoint pen tip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dry an ink or leak ink at a front end without pressing a rear end of a ball properly by a coil spring for pressing a rear end of the ball and urging the ball forward. As much as possible, and in order to secure an ink flow path, it suppresses writing blur as much as possible.
A coil-like member is formed on a straight part of a coil spring so as to cover an outer diameter part conforming to the inner diameter of the through hole in which the straight part is located and a small-diameter part conforming to the center hole diameter.
[Selection] Figure 2

Description

  According to the present invention, a ball as a writing member and a tip opening of the through hole are formed with a diameter smaller than the diameter of the ball, and the ball is inserted into the tip opening of the through hole by a plurality of inward protruding portions formed on the inner wall of the through hole. A ball holder that protrudes more partly and is rotatably held, and a central hole that is formed at the center part of the inward protruding part with a straight part formed at least at the through hole of the ball holder and formed at the tip The present invention relates to a ball-point pen tip having at least a coil spring that is inserted through and abutted against a ball to urge forward.

Conventionally, a coil spring that repels from the inside of the ball holder to prevent ink from being written due to drying of the ink in the ballpoint pen tip and ink leakage from the gap between the ball and the ball holder when not in use. It is known that the ball is urged toward the tip of the ball, the ball is brought into circumferential contact with the inner wall of the ball holder, and the gap between the ball and the ball holder is sealed.
The part that presses the back of the ball includes a part in which the tip of the coil portion of the coil spring is brought into contact with the back of the ball, but in the first place, a so-called pipe-type chip formed by processing a pipe-like member. In a ballpoint pen tip with a small inner diameter, the coil portion of the coil spring may be difficult to have an outer diameter smaller than the inner diameter, so the straight portion extends from the tip in the axial direction of the coil portion, A technique is known in which the front end of the straight portion is brought into contact with the rear portion of the ball to urge the ball forward.

However, the straight part of the coil spring may incline with respect to the axis of the coil part, and this inclination causes the tip of the coil spring to be caught on the rear surface of the inward projecting part that regulates the rear of the ball, and the ballpoint pen tip. There was a problem that ink could not be written due to drying of the ink inside, and ink leaked from the gap between the ball and the ball holder when not in use.
In order to improve this problem, in Patent Document 1, the straight part of the coil spring that directly pushes the ball is not installed in a state where the coil spring is caught by the inner hole of the ball holder and does not bias the ball. As described above, an inclined smooth surface is formed at the center of the rear surface of the inward protruding portion, and the smooth surface is made smoother than the rear surface of the inward protruding portion other than the smooth surface. Has been.
Further, in Patent Document 2, a coil spring that biases the writing ball forward is disposed in the ink passage hole, and reaches the vicinity of the inner wall of the ball holder at the straight portion of the tip of the coil spring that directly contacts the ball. Disclosed is a member that is arranged in a separate member (soft communicating porous body) and in which the straight portion is not easily inclined.

JP 2010-52391 A JP 2002-356085 A

However, in the invention described in Patent Document 1, there is a problem in certainty because friction between members is reduced as much as possible.
Further, in the invention described in Patent Document 2, even if the porous material is disposed, it is a great obstacle to the ink flow, and if the gap between the members is increased, it is difficult to obtain a sufficient tilt prevention effect. It was to become.

  According to the present invention, a ball as a writing member and a tip opening of the through hole are formed with a diameter smaller than the diameter of the ball, and the ball is inserted into the tip opening of the through hole by a plurality of inward protruding portions formed on the inner wall of the through hole. A ball holder that protrudes more partly and is rotatably held, and a central hole that is formed at the center part of the inward protruding part with a straight part formed at least at the through hole of the ball holder and formed at the tip In a ballpoint pen tip having at least a coil spring that is inserted into the ball and abutted against the ball to urge forward, an outer diameter portion conforming to the inner diameter of the through hole in which the straight portion is located in the straight portion of the coil spring The gist of the present invention is a ball-point pen tip that is covered with a coil-shaped member in which a small-diameter portion having a diameter equal to or larger than the outer diameter of the straight portion and the diameter of the central hole or less is formed.

According to the present invention, the coil-shaped member covered the straight portion of the coil spring that urges the writing ball forward, and the outer diameter portion of the coil-shaped member conforms to the inner diameter of the through hole of the ball holder. By setting the size and making the small diameter portion equal to or smaller than the center hole diameter and the outer diameter of the straight portion, the straight portion is guided and arranged at a desired position, so that the writing ball can be pushed reliably.
Moreover, since the coil-shaped member has sufficient gaps that allow ink distribution, it is possible to ensure a sufficient distribution of ink.
Furthermore, since it is a coil-shaped member, it can be formed in the same manner as a so-called coil spring by processing a metal wire, and is inexpensive and easy to assemble.

The longitudinal cross-sectional view which shows an example. The I section enlarged view of FIG. The principal part expansion longitudinal cross-sectional view which shows another example.

  As the material of the ball, a super hard material mainly composed of tungsten carbide, titanium, cobalt, chromium, nickel, etc., ceramic such as silicon carbide, silicon nitride, titanium nitride, alumina, zirconia, or the like can be used.

The ball holder has a ball as a writing member disposed in a through-hole as an ink passage, and has an inward protruding portion as a retraction restricting portion of the ball, for supplying ink around the ball to the inward protruding portion. A radial groove communicating with the center hole and the rear hole is formed.
The tip opening portion has a shape of a ball-point pen tip in which the ball is rotatably held in a state in which a part of the ball protrudes after the ball is disposed and is reduced in diameter to be smaller than the diameter of the ball.
As the material of the ball holder, a metal such as stainless steel, brass, or white can be used. Moreover, there are a thing which uses a coil wire, and a thing which uses a pipe material with a medium hole beforehand.

The coil spring that urges the writing ball forward must pass through the center hole, which is the small diameter part of the through hole of the ball holder, to urge the ball forward, so the tip part is formed as a straight part without winding. To do. By urging the ball forward, the ball is pressed against the inner edge of the opening of the ball holder to block outflow of ink. That is, the coil spring can be suitably used for a retractable ballpoint pen that mainly moves a ballpoint pen refill provided with a ballpoint pen tip at the tip without moving the cap as a separate member and causes the pen tip to protrude and retract. is there.
The length of the straight portion of the coil spring is appropriately adjusted as the length necessary to reach the ball, but the longer the position, the tip position and the axial center of the coil portion shift with respect to a slight inclination. When inserting and installing in the holder, there is a high possibility of contact with the inner wall of the ball holder, which may make assembly difficult. In addition, it is difficult to determine the position of the tip of the straight portion with a parts feeder or the like, and it may be difficult to insert a coiled member to be described later.

The straight part of the coil spring is covered with a coiled member. The coil-shaped member can be a metal such as stainless steel or an injection-molded product of synthetic resin. However, since the coil-shaped member is a member that comes into contact with ink, a material that does not react with ink is selected as with the coil spring. Like a coil spring, it is preferable to wind a stainless steel wire and cut it to an appropriate length so that a member having a desired shape can be easily formed.
The coil-shaped member has a sufficient gap between the outer surface and the inner surface to allow ink distribution, and it is necessary to enlarge the gap as much as possible in order to ensure abundant ink distribution. In the case of using an automatic feeder called a parts feeder at the stage of assembling the member, it is preferable to make the gap not more than the wire diameter of the coil member in order to prevent the coil members from being entangled.
In addition, the inner diameter of the coiled member is equal to or smaller than the inner diameter of the inner hole formed at the center of the inward projecting portion and is equal to or larger than the outer diameter of the straight portion of the coil spring. The shape portion is less likely to contact the rear surface of the inward projection of the ball holder.
The coil-like member can be formed to be stretchable in the form of a coil spring, in which case the minimum value of the winding inner diameter is less than the linear shape of the straight part of the coil spring that biases the ball forward. Even if it has a small diameter, it can be inserted by its stretchability, and the straight portion can be clamped. When the straight part is sandwiched, it can be handled as an integral combination member, which can contribute to ease of assembly.

The outer diameter of the coil-shaped member is set to be the same as or slightly smaller than the inner diameter of the through hole of the ball holder where the straight portion of the coil spring is located. This is because the outer diameter of the coil-shaped member substantially contacts the inner diameter to correct the position of the straight portion of the coil spring. The outer diameter of the coil-shaped member and the inner diameter of the through hole of the ball holder may be in a fitting relationship that does not substantially differ, but it is also possible to contribute to ink circulation by having a gap. In particular, when it is located in the center hole that opens at the center of the inward projection, which is the small diameter portion of the through hole of the ball holder, the tip of the coil spring contacts the rear surface of the inward projection. Since it becomes difficult, an assemblability improves, and it is preferable.

  As the shape of the coil-shaped member, if the outer diameter portion conforming to the inner diameter of the through hole of the ball holder and the smaller diameter portion having a diameter equal to or larger than the outer diameter of the straight portion smaller than the central hole diameter, the position of the smaller diameter portion is Any of the front end, the rear end, and the middle can be employed. When the coil-shaped member is previously installed in the ball holder prior to the coil spring, the inner diameter of the coil-shaped member is provided with a portion that gradually decreases toward the front, that is, the small-diameter portion is on the distal side from the middle. It can be said that it is preferable to be formed.

The coil spring that biases the writing ball forward restricts the forward movement by contacting the ball in the front, and the rear is reduced in diameter on the rear end side of the ball holder to prevent the coil portion from coming off or another member. It is possible to restrict rearward movement by providing a tip holder and installing an inner step in the tip holder.
Only the straight part may be inserted into the ball holder, or a part or the whole of the coil part may be inserted.

  A coil spring and a coil-shaped member are inserted into the ball-point pen tip constituted by the ball and the ball holder as described above, and an ink containing portion is connected directly or via a connecting member to the ball-point pen body. When this ball-point pen body is accommodated in the exterior body, it becomes what is called a refill. For example, it can be a retractable ball-point pen that appears and disappears from the front end portion of the exterior body by an operation.

  The ink containing member contains ink in a free state, and a high-viscosity fluid may be arranged as a backflow preventer at the ink interface. Further, the discharge may be supported by pressing the ink by, for example, enclosing compressed air in the ink containing portion. The materials constituting the ink storage member are polyamide resin, vinyl chloride resin, ethylene vinyl alcohol copolymer, polyacrylonitrile, fluororesin, polyacetal resin, polyethylene, polypropylene, polyethylene terephthalate, polycarbonate resin, polystyrene resin, ABS resin. Various materials such as resin such as polybutylene terephthalate, polybutylene naphthalate, polyethylene naphthalate, and metals such as stainless steel can be used, but it is necessary to consider the ease of manufacturing, ink color visibility, vapor permeability, etc. There is. It is also appropriate to color this extruded pipe or to add pigments or extenders.

  FIG. 1 shows a ball holder 3 in which a ball 1 as a writing member is rotatably held in a state of partially protruding from a tip opening 2, and an ink that is an extruded pipe such as polypropylene resin. The housing tube 4 is an example of a ballpoint pen formed by joining with a chip holder 5 formed of polybutylene terephthalate resin or the like. In FIG. 1, it is shown as what is called a refill that is housed and used in an exterior body, but illustration and description of the exterior are omitted. Ink 7 is accommodated in the ink storage tube 4, and a backflow preventing body composition 8, which is a high-viscosity fluid that is incompatible with the ink 7, is disposed in contact with the rear end interface of the ink 7. In particular, when the low-viscosity ink 7 is used, it is effective to dispose the backflow prevention body composition 8 in order to suppress the ink 7 from moving backward.

  As shown also in FIG. 2 which is an enlarged view of the I part of FIG. A ball holding chamber 10 as a range in which the ball 1 can move is formed by the tip opening portion 2 having a small diameter and the inward protruding portion 9 that restricts the backward movement of the ball 1. The through hole is substantially connected to the center hole 11 formed at the center of the inward projecting portion 9, the radial groove 12 formed between the inward projecting portions 9, and the ink containing tube 3 side. A rear hole 13 is provided. Further, the surface of the inward projecting portion 9 on the side of the ball holding chamber 10 presses the ball 1 with a pressing tool (not shown) from the tip side, and has a seat having a surface with substantially the same curvature as the ball 1. A surface 14 is formed. Thus, an amount of movement substantially before and after the ball 1 is secured. The radial grooves 12 are open on the outer side of the ball holding chamber 10 and the rear hole 13 side, so that ink is supplied to the portion not blocked by the ball 1 even when the ball 1 moves to the rear end. In addition, sufficient ink can be supplied from the rear hole 13.

  Inside the rear hole 13 of the ball holder 3, a coil spring 15 including a winding portion 15a that expands and contracts to prevent ink leakage and a straight portion 15b is disposed to urge the ball 1 forward.

  The coil-shaped member 16 is inserted into the rear hole 13, and then the coil spring 15 is inserted into the coil-shaped member 16. At the same time, the coil spring 15 is in a state where the full length is compressed, and the straight portion 15b is 1 and is held and held by the bottom surface portion 5 b of the front end insertion hole 5 a of the chip holder 5.

The coil-shaped member 16 is formed of a linear body of SUS304 stainless steel, and a gap 17 is provided between the outer surface and the inner surface so that ink can be circulated, and the rear surface of the ball is pressed inward. A straight portion 15b extending from the coil spring is disposed so as to cover it. The gap 17 is appropriately adjusted so as not to disturb the ink flowability. In this case, the gap is set to 0.05 mm.
On the other hand, the wire diameter of the coil-shaped member 16 is 0.07 mm, the outer diameter of the coil spring winding portion 15a is 0.28 mm, and the inner diameter is 0.14 mm.
The inner diameter of the rear hole 13 of the ballpoint pen tip is set to 0.30 mm, and the inner diameter of the center hole 11 formed at the center of the inward protruding portion 9 is set to 0.16 mm.
That is, the shape of the coil-shaped member is such that an outer diameter portion conforming to the inner diameter of the through hole in which the straight portion is located and a small diameter portion having a diameter equal to or larger than the outer diameter of the straight portion equal to or smaller than the central hole diameter. Therefore, the straight part of the coil spring that passes through here is difficult to come into contact with the rear surface of the inward projection of the ball holder.

FIG. 3 shows another example.
The difference from the above-described example is that the outer diameter of the coil-shaped member does not have substantially the same diameter from the front end to the rear end, but includes a portion in which the inner diameter of the coil-shaped member gradually decreases toward the front. Is.
In the coil-shaped member 16 having this shape, when the straight portion 15b of the coil spring 15 is placed on the coil-shaped member 16, the straight portion 15b is slightly inclined with respect to the axis of the coil spring winding portion 15a. However, since the inclination of the straight portion 15b is gradually reduced toward the center, the assemblability is improved.
The size of the gap 17 is 0.07 mm. The wire diameter of the coil-shaped member 16 is 0.11 mm, the maximum outer diameter located behind the coil spring winding 15a is 0.49 mm, and the minimum outer diameter located ahead of the winding 15a is 0. 28 mm, the inner diameter of the maximum outer diameter portion is 0.38 mm, the inner diameter of the minimum outer diameter portion is 0.17 mm, the inner diameter of the rear hole 13 of the ballpoint pen tip is 0.50 mm, and the center of the inward protruding portion 9 is The inner diameter of the formed center hole 11 is set to 0.26 mm.
That is, the shape of the coil-shaped member is such that an outer diameter portion conforming to the inner diameter of the through hole in which the straight portion is located and a small diameter portion having a diameter equal to or larger than the outer diameter of the straight portion equal to or smaller than the central hole diameter. Therefore, the straight part of the coil spring that passes through here is difficult to come into contact with the rear surface of the inward projection of the ball holder.

DESCRIPTION OF SYMBOLS 1 Ball | bowl 2 Ball holder 3 Front-end opening part 4 Ink storage pipe 5 Tip holder 5a Front end insertion hole 5b Bottom part 6 Small diameter part 7 Ink 8 Backflow prevention body composition 9 Inward protrusion part 10 Ball holding chamber 11 Center hole 12 Radial groove 13 Rear hole 14 Seating surface 15 Coil spring 15a Winding part 15b Straight part 16 Coiled member 17 Gap

Claims (1)

The ball as a writing member and the tip opening of the through hole are made smaller in diameter than the diameter of the ball, and the ball partially protrudes from the tip opening of the through hole by a plurality of inward protrusions formed on the inner wall of the through hole. A ball holder that is held in a freely rotating manner, and at least part of the ball holder is disposed in the through hole of the ball holder, and a straight hole formed at the tip is inserted through the central hole formed in the central portion of the inward protruding portion. In a ballpoint pen tip having at least a coil spring that abuts against a ball and urges forward, an outer diameter portion and a center hole diameter conforming to the inner diameter of the through hole in which the straight portion is positioned A ball-point pen tip having a coil-shaped member formed with a small-diameter portion having a diameter equal to or larger than the outer diameter of the straight portion.

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