JP4878217B2 - Ballpoint pen tip and ballpoint pen refill - Google Patents

Description

  The present invention relates to a ballpoint pen tip having an ink backflow prevention mechanism.

In a conventional ballpoint pen in which ink is directly filled in an ink storage tube, the ink is supplied to the writing tip by the weight of the ink. Therefore, when writing with the writing tip facing upward (referring to the state where the writing tip is pointing upward from the horizontal), if the writing tip is left facing upward with the writing disabled, ink will be ejected from the pen rear end. There is a problem that a leakage phenomenon occurs (hereinafter, this phenomenon is referred to as “backflow”), and in some cases, the clothes are soiled.
As a countermeasure against such a backflow, as shown in Patent Document 1 below, another ball is provided behind the writing ball. That is, a step for narrowing the inner diameter is provided on the tip side of the ball, and a plurality of channel grooves are radially engraved on the step. Further, the rear end side of the ball is narrowed to have a diameter smaller than the diameter of the ball. When the writing tip is turned downward, the ball moves toward the tip, but the ink flow to the tip is not obstructed by the channel groove. On the other hand, when the writing line is directed upward, the ball closes the narrowed portion on the rear end side, thereby preventing the ink from flowing backward. That is, this ball functions as a backflow prevention valve.

In addition to this reverse flow phenomenon, when ink having a relatively low viscosity such as a water-based ballpoint pen is used, the ink leaks from the writing tip (hereinafter, this phenomenon is referred to as “direct current” in the present specification). ) Is a problem. As such a direct current countermeasure, as in the invention disclosed in Patent Document 2 below, it is common to prevent backflow by always biasing the writing ball toward the tip by a spring inserted into the ballpoint pen tip. .
Japanese Utility Model Publication No. 57-4373 (FIGS. 1 and 2) JP-A-10-329475 (FIGS. 1 to 3)

In the case where a step or a channel groove is provided on the tip side of the backflow preventing ball in the ballpoint pen tip as in the prior art disclosed in Patent Document 1, a plurality of cutting steps are required. This complicates the ball-point pen chip manufacturing process. In addition, fine chips are generated by the cutting process. If such chips remain in the ball-point pen tip, the chips adhere to the writing ball on the writing tip side, and a feeling of sag or roughness may occur during writing.
Accordingly, the first object of the present invention is to hold a backflow prevention ball in the ballpoint pen tip and sufficiently exhibit the backflow prevention function without going through a cutting process in which such generation of chips is unavoidable. To do.

  In addition to the first problem described above, the second object of the present invention is to impart a direct current preventing function to the ballpoint pen tip by pressing the writing ball with a spring.

(1) 1st invention In order to solve the said 1st subject, the ball-point pen tip 20 which concerns on 1st invention among this invention,
A holder 30 formed by cutting a cylindrical material;
A tapered portion 31 formed by tapering the outer periphery of one end of the holder 30, and
A ball house 33 formed by cutting the inner periphery of the tapered portion 31, and
A back hole 35 formed by drilling from the other end of the holder 30 to the vicinity of the ball house 33;
An ink hole 36 which is a hole having a circular cross section formed between the ball house 33 and the back hole 35;
A channel groove 37 which is a groove formed by cutting a plurality of locations equally distributed around the ink hole 36 from the ball house 33 side and opening the ink hole 36;
A writing ball 21 inserted into the ball house 33;
A ball seat 38 to which the curved surface of the writing ball 21 is transferred when the writing ball 21 is pressed toward the back hole 35 on the bottom surface of the ball house 33;
A tip caulking portion 39 formed by caulking the tip portion of the taper portion 31 inside; and
An inward projection 40 provided by pressing and deforming the vicinity of the rear end of the holder 30 from the outside and projecting inward of the back hole 35, and
A backflow prevention ball 24 inserted into the back hole 35 between the inner protrusion 40 and the rear end of the back hole 35;
A back end caulking portion 41 formed by caulking the back end portion of the back hole 35 inside is provided.

The “holder 30” refers to a main body portion obtained by removing the “writing ball 21” from the ballpoint pen tip 20, and is formed by cutting a metal cylindrical material such as stainless steel. A portion obtained by tapering the front end side of the holder 30 is referred to as a “taper portion 31”. The rear end side of the holder 30 is not particularly limited, but it may be cut to reduce the outer diameter to form a portion to be inserted into the “ink containing tube 11” or a joint interposed therebetween. it can.
The “ball house 33” refers to a space formed by cutting the inner periphery from the tip end side of the tapered portion 31, into which the writing ball 21 is inserted.
The “back hole 35” is a central hole cut from the rear end of the holder 30 to the vicinity not reaching the ball house 33, and the ink 12 contained in the “ink containing tube 11” is guided to the ball house 33 through this central hole It is supposed to be done.

The “ink hole 36” is a central hole having a smaller diameter than the back hole 35 that connects the back hole 35 and the ball house 33.
The “channel grooves 37” are a plurality of axial grooves arranged at equal intervals around the ink holes. The ink 12 guided to the tip of the back hole 35 reaches the ball house 33 from the ink hole 36 via the channel groove 37.
The “writing ball 21” is a metal sphere such as super hard stainless steel and is inserted into the ball house 33. The ink 12 reaching the ball house 33 adheres to the surface of the writing ball 21 and is transferred to the writing surface.

The “ball seat 38” is formed by pressing the writing ball 21 inserted into the ball house 33 backward by so-called “tacking”, and transferring the curved surface of the writing ball 21 to the bottom surface 34 of the ball house 33. A concave curved surface.
The “tip crimping portion 39” is a structure that prevents the writing ball 21 from falling by crimping the tapered portion 31 after inserting the writing ball 21 inward to reduce the inner diameter.
The “inward protrusion 40” is a protrusion-like structure formed in the vicinity of the rear end of the holder 30 to hold the backflow prevention ball 24 on the front end side. The inward protruding portion 40 is formed as a protrusion protruding inward from the outside by pressing plastic deformation, for example, by a three-point punch. The minimum diameter portion formed by the tips of these protrusions is smaller than the diameter of the backflow prevention ball 24. That is, since the content protrusion 40 is formed by pressing plastic deformation regardless of the cutting process, chips are not generated due to cutting, and there is no trouble such as a loss of writing feeling. In order to eliminate this, a washing step is not necessary.

The “backflow prevention ball 24” is a valve structure for preventing the backflow of the ink 12 when the writing tip is directed upward, and the inner protrusion 40 is formed in the back hole 35 near the rear end of the holder 30. And a rear end caulking portion 41 described below.
The “rear end caulking portion 41” refers to a portion where the back end preventing ball 24 is deformed inward and the inner diameter is narrowed to prevent the backflow preventing ball 24 from falling from the rear end of the holder 30.
The ball-point pen tip 20 according to the first aspect of the invention is used as the ink refill 10 by being attached to the tip of the ink storage tube 11 that stores the ink 12 therein. Further, the ink refill 10 is used as the ballpoint pen 10 by being mounted inside the shaft tube. Here, the “ink storage tube 11” is a tube made of synthetic resin such as polypropylene having a relatively low hardness, and the ink 12 is stored therein.

When the ball-point pen tip 20 according to the first invention is mounted on the ink refill 10 and further used as the ball-point pen 10, it operates as follows.
First, when writing is performed with the writing tip facing downward, the backflow prevention ball 24 moves toward the tip in the back hole 35, but is captured by the plurality of inward projections 40 and further moves to the tip. There is nothing. At this time, since there is a gap between the adjacent inward projections 40, ink distribution from the ink containing tube 11 to the writing tip is ensured through this gap.
On the other hand, when writing is performed with the writing tip facing upward, the backflow prevention ball 24 moves toward the rear end in the back hole 35, but is captured by the rear end caulking portion 41 and further moves to the rear end. There is nothing. At this time, the backflow prevention ball 24 completely blocks the opening of the rear end caulking portion 41 from the inside, so that the backflow of the ink 12 from here to the rear end is prevented.

(2) Second invention In order to solve the second problem described above, the ball-point pen tip 20 according to the second invention of the present invention is provided in the back hole 35 in addition to the features of the first invention. The rear end of the spring 22 that is inserted and the front end portion is formed as a pressing rod 23 that presses the writing ball 21 toward the front end is supported by the front end portion of the inward projection 40. .
The ball-point pen tip 20 according to the second aspect of the present invention is used as the ink refill 10 by being attached to the tip of the ink storage tube 11 that stores the ink 12 therein. Further, the ink refill 10 is used as the ballpoint pen 10 by being mounted inside the shaft tube. Here, the “ink storage tube 11” is a tube made of synthetic resin such as polypropylene having a relatively low hardness, and the ink 12 is stored therein.

The ballpoint pen tip 20 according to the second aspect of the invention acts as follows when mounted on the ink refill 10 and further used as the ballpoint pen 10.
First, when writing is performed with the writing tip facing downward, the backflow prevention ball 24 moves toward the tip in the back hole 35, but is captured by the plurality of inward projections 40 and further moves to the tip. There is nothing. At this time, since there is a gap between the adjacent inward projections 40, ink distribution from the ink containing tube 11 to the writing tip is ensured through this gap.
On the other hand, when writing is performed with the writing tip facing upward, the backflow prevention ball 24 moves toward the rear end in the back hole 35, but is captured by the rear end caulking portion 41 and further moves to the rear end. There is nothing. At this time, the backflow prevention ball 24 completely blocks the opening of the rear end caulking portion 41 from the inside, so that the backflow of the ink 12 from here to the rear end is prevented.

  In addition, the urging force of the spring 22 causes the writing ball 21 to be pressed in the distal direction by the pressing rod 23, but the inward projection 40 functions as a portion that supports this urging force. ing. As a result, particularly when a water-based gel ink having a relatively low viscosity is used as the ink 12, the writing ball 21 is always pressed toward the tip, so that the writing ball 21 and the tip caulking portion 39 are not in writing. Will close the clearance. As a result, direct current of the ink 12 during non-writing is prevented.

Since this invention is comprised as mentioned above, there exists an effect described below.
That is, according to the configuration of the first invention of the present invention, the backflow prevention ball is held in the ballpoint pen tip and the backflow prevention function is sufficiently exhibited without going through a cutting process in which generation of chips is unavoidable. Is possible.
According to the second aspect of the present invention, in addition to the above effects, it is possible to impart a direct current preventing function to the ballpoint pen tip by pressing the writing ball with a spring.

(1) First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a front sectional view showing a state in which the writing tip is directed downward in the ball-point pen tip according to the present embodiment. FIG. 2 is a front cross-sectional view of the ballpoint pen tip according to the present embodiment with the writing tip facing upward. FIG. 3 is a cross-sectional view taken along the line AA in FIG. FIG. 4 is a front sectional view showing a manufacturing process of the ballpoint pen tip according to the present embodiment. FIG. 5 is a front sectional view showing a state where the ballpoint pen tip according to the present embodiment is mounted on the ballpoint pen refill.

The ball-point pen tip 20 according to the present embodiment has a shape as shown in FIGS. That is, the front end portion of the stainless steel columnar holder 30 is tapered to form a tapered portion 31 and the rear end portion is formed as an insertion portion 32 with a reduced outer diameter. Yes. The inserted portion 32 is a portion that is press-fitted into the tip of the ink containing tube 11. Further, the tip of the writing ball 21 held inside the taper 31 is exposed from the tip edge of the taper 31, and the tip of the taper 31 is formed as a tip caulking part 39 that is pressed inward and deformed to a reduced diameter. (See FIGS. 1C and 2B).
Inside the ball-point pen tip 20, the inner periphery of the tip of the tapered portion 31 is cut to form a ball house 33 that holds the writing ball 21 made of cemented carbide stainless steel (FIGS. 1C and 2). (See (B)). On the other hand, from the rear end of the holder 30, a back hole 35 whose diameter is gradually reduced is formed to a position near the rear end of the tapered portion 31 (see FIGS. 1A and 2A). Further, an ink hole 36 having a smaller inner diameter than the back hole 35 is formed so as to connect the back hole 35 and the ball house 33. In addition, channel grooves 37 that are radially distributed around the ink holes 36 are formed from the bottom surface 34 of the ball house 33 (see FIGS. 1C and 2B).

When the ball-point pen tip 20 is formed, the writing ball 21 is inserted into the ball house 33 to further form the tip crimping portion 39, and then a tacking process is performed in which the writing ball 21 is pressed toward the rear end. As a result, the spherical surface of the writing ball 21 is transferred to the bottom surface 34 of the ball house 33 to form the ball seat 38 (see FIGS. 1C and 2B).
On the other hand, in the vicinity of the rear end of the holder 30, pressing plastic deformation is performed from the outside by a three-point punch, and as a result, protrusions protruding inward are formed at three locations. This protrusion is referred to as an inward protrusion 40 (see FIG. 3). A backflow prevention ball 24 made of cemented carbide or stainless steel slightly smaller than the inner diameter of the rear end portion of the back hole 35 is located behind the inward projection 40 (FIGS. 1B and 2C). )reference).

The rear end of the holder 30 is inwardly crimped so that the inner diameter is smaller than the diameter of the backflow prevention ball 24. This portion is referred to as a rear end crimping portion 41 (see FIGS. 1B and 2C).
The manufacturing process of the ballpoint pen tip 20 according to the present embodiment is as follows.
First, cutting is performed so as to reduce the outer diameter of the rear end portion of the columnar material that becomes the holder 30, and the inserted portion 32 is formed. On the other hand, the tip portion on the opposite side is cut into a tapered shape, and a tapered portion 31 is formed.
Next, the back hole 35 is cut from the rear end of the holder 30 to the vicinity of the rear end position of the tapered portion 31 in the front end direction while reducing the inner diameter of the drill in three stages. Further, the latter half of the ink hole 36 is cut to the vicinity of the middle position of the tapered portion 31 by using a drill having a reduced inner diameter.

This time, the ball house 33 is cut from the tip of the holder 30 by using a slightly larger diameter drill than the drill that cuts the latter half of the ink hole 36 described above. Then, the front half portion of the ink hole 36 is caused to penetrate backward from the bottom surface 34 of the ball house 33 using a drill having a slightly smaller diameter than the drill obtained by cutting the latter half portion of the ink hole 36. Further, using a channel tool, the channel groove 37 is cut from the bottom surface 34 of the ball house 33 to the rear until it reaches almost the middle of the front half of the ink hole 36. At this stage, the holder 30 is subjected to a cleaning process for chips generated by cutting.
After the writing ball 21 is placed in the ball house 33, the tip edge of the tapered portion 31 is subjected to caulking with a caulking tool. Thereby, the front end edge of the taper part 31 becomes the front end crimping part 39 in a state where the inner diameter is narrowed so as to hold the writing ball 21 (see FIGS. 1C and 2B). Further, by applying a load in the rear end direction to the writing ball 21, the spherical surface of the writing ball 21 is transferred to the bottom surface 34 of the ball house 33, and a ball seat 38 is formed (FIG. 1C and FIG. 2 (B)). At this stage, the state shown in FIG.

Next, in the vicinity of the rear end of the holder 30, pressing plastic deformation is performed from the outside by a three-point punch to form inward projections 40 at three locations (see FIG. 3). And the backflow prevention ball | bowl 24 is inserted from the rear end of the holder 30 (FIG.4 (C)). Further, the rear end edge is caulked inward by a caulking tool to form a rear end caulking portion 41 (FIG. 4D), and the ballpoint pen tip 20 is completed here.
The ball-point pen tip 20 is press-fitted and fixed to the tip of the polypropylene ink containing tube 11 with the inserted portion 32. On the other hand, the ink 12 is filled from the rear end of the ink containing tube 11 and the ink refill 10 is completed (FIG. 5).

In the ball-point pen tip 20 according to the present embodiment, the backflow prevention ball 24 moves in the tip direction by its own weight as shown in FIG. Abut. At this time, a gap is formed between the writing ball 21 and the rear edge of the holder 30. In addition, since there is a gap between the inward protrusions 40, the ink flow from the ink containing tube 11 to the writing tip direction through the back hole 35 is ensured through these gaps.
On the other hand, when the writing tip is directed upward, as shown in FIG. 2C, the backflow prevention ball 24 moves toward the rear end due to its own weight and comes into contact with the inner edge of the rear end caulking portion 41. Accordingly, the back hole 35 is closed by the backflow prevention ball 24, and the backflow of the ink 12 from the tip toward the ink storage tube 11 is prevented.

(2) Second Embodiment Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.
FIG. 6 is a front sectional view showing a state in which the writing tip is directed downward in the ball-point pen tip according to the present embodiment. FIG. 7 is a front sectional view showing a state in which the writing tip is directed upward in the ball-point pen tip according to the present embodiment. FIG. 8 is a cross-sectional view taken along the line BB in FIG. FIG. 9 is a front sectional view showing a state where the ballpoint pen tip according to the present embodiment is mounted on the ballpoint pen refill.
The ball-point pen tip 20 according to the present embodiment has a shape as shown in FIGS. That is, the front end portion of the stainless steel columnar holder 30 is tapered to form a tapered portion 31 and the rear end portion is formed as an insertion portion 32 with a reduced outer diameter. Yes. The inserted portion 32 is a portion that is press-fitted into the tip of the ink containing tube 11. Further, the tip of the writing ball 21 held inside the taper 31 is exposed from the tip edge of the taper 31, and the tip of the taper 31 is formed as a tip caulking part 39 that is pressed inward and deformed to a reduced diameter. (See FIGS. 6C and 7B).

  Inside the ball-point pen tip 20, the inner periphery of the tip of the tapered portion 31 is cut to form a ball house 33 that holds the writing ball 21 made of super hard stainless steel (FIGS. 6C and 7). (See (B)). On the other hand, from the rear end of the holder 30, a back hole 35 whose diameter is gradually reduced is formed to a position near the rear end of the tapered portion 31 (see FIGS. 6A and 7A). Further, an ink hole 36 having a smaller inner diameter than the back hole 35 is formed so as to connect the back hole 35 and the ball house 33. In addition, channel grooves 37 that are radially distributed around the ink holes 36 are formed from the bottom surface 34 of the ball house 33 (see FIGS. 6C and 7B).

When the ball-point pen tip 20 is formed, the writing ball 21 is inserted into the ball house 33 to further form the tip crimping portion 39, and then a tacking process is performed in which the writing ball 21 is pressed toward the rear end. As a result, the spherical surface of the writing ball 21 is transferred to the bottom surface 34 of the ball house 33 to form the ball seat 38 (see FIGS. 6C and 7B).
On the other hand, in the vicinity of the rear end of the holder 30, pressing plastic deformation is performed from the outside by a three-point punch, and as a result, protrusions protruding inward are formed at three locations. This protrusion is referred to as an inward protrusion 40. A backflow prevention ball 24 made of cemented carbide or stainless steel slightly smaller than the inner diameter of the back end of the back hole 35 is located behind the inward projection 40 (FIGS. 6B and 7C). )reference).

The rear end of the holder 30 is inwardly crimped so that the inner diameter is smaller than the diameter of the backflow prevention ball 24. This portion is referred to as a rear end caulking portion 41 (see FIGS. 6B and 7C).
Further, a spring 22 formed by a coil spring is inserted into the back hole 35. The rear end of the spring 22 is in contact with and supported by the front end side of the inward projection 40. On the other hand, the tip of the spring 22 is formed as a pressing rod 23 that extends straight toward the tip. The front end of the pressing bar 23 abuts against the rear end of the writing ball 21 through the ink hole 36, thereby urging the writing ball 21 in the front end direction.

The ball-point pen tip 20 is press-fitted and fixed to the tip of the polypropylene ink containing tube 11 with the inserted portion 32. On the other hand, the ink 12 is filled from the rear end of the ink containing tube 11, thereby forming the ink refill 10 shown in FIG. 9.
Now, with the ballpoint pen tip 20 according to the present embodiment, the backflow prevention ball 24 moves toward the tip due to its own weight as shown in FIG. Abut. At this time, a gap is formed between the writing ball 21 and the rear edge of the holder 30. In addition, since there is a gap between the inward protrusions 40, the ink flow from the ink containing tube 11 to the writing tip direction through the back hole 35 is ensured through these gaps. In addition, since the pressing rod 23 always presses the writing ball 21 toward the tip due to the urging force of the spring 22, the clearance between the tip crimping portion 39 and the writing ball 21 is closed when not writing. become. As a result, even when the ink 12 having a relatively low viscosity such as the water-based gel ink is used, direct current of the ink 12 from the tip is prevented.

  On the other hand, when the writing tip is directed upward, as shown in FIG. 7C, the backflow prevention ball 24 moves toward the rear end due to its own weight and comes into contact with the inner edge of the rear end caulking portion 41. Accordingly, the back hole 35 is closed by the backflow prevention ball 24, and the backflow of the ink 12 from the tip toward the ink storage tube 11 is prevented.

  The present invention can be used as a ballpoint pen tip or a ballpoint pen refill used in a ballpoint pen.

In the first embodiment of the present invention, the entire ballpoint pen tip (A), rear end portion (B) and front end portion (C) with the writing front end facing downward are shown in a front sectional view. In the first embodiment of the present invention, the entire ball pen tip (A), front end portion (B) and rear end portion (C) with the writing front end facing upward are shown in a front sectional view. It is AA sectional drawing of FIG. 2 (A). The manufacturing process of the ball-point pen tip which concerns on the 1st Embodiment of this invention is shown with front sectional drawing. The state which mounted | wore the ball-point pen refill with the ball-point pen tip concerning the 1st Embodiment of this invention is shown with front sectional drawing. In the 2nd Embodiment of this invention, the whole (A), rear end part (B), and front-end | tip part (C) of the ball-point pen tip in the state which set the writing front-end | tip downward are shown by front sectional drawing. In the 2nd Embodiment of this invention, the whole (A), front-end | tip part (B), and rear-end part (C) of the ball-point pen tip in the state where the writing front-end | tip was turned up are shown with front sectional drawing. It is BB sectional drawing of FIG. 7 (A). The state which mounted | wore the ball-point pen refill with the ball-point pen tip concerning the 2nd Embodiment of this invention is shown with front sectional drawing.

Explanation of symbols

10 Increfill 11 Ink receiving tube 12 Ink
20 Ballpoint pen 21 Writing ball 22 Spring
23 Press rod 24 Backflow prevention ball
30 Holder 31 Tapered part 32 Inserted part
33 Ball house 34 Bottom 35 Back hole
36 Ink hole 37 Channel groove 38 Ball seat
39 Leading caulking part 40 Inward protrusion 41 Rear end caulking part

Claims (3)

A metal holder formed by cutting a cylindrical material;
A tapered portion formed by tapering the outer periphery of one end of the holder;
A ball house formed by cutting the inner periphery of the tapered portion;
A back hole formed by drilling from the other end of the holder to the vicinity of the ball house;
An ink hole that is a hole having a circular cross section formed between the ball house and the back hole;
A channel groove which is a groove formed by cutting a plurality of locations equally distributed around the ink hole from the ball house side and opening the ink hole;
A metal writing ball inserted into the ball house;
A ball seat to which the curved surface of the writing ball is transferred when the writing ball is pressed toward the back hole on the bottom surface of the ball house;
A tip caulking portion formed by caulking the tip portion of the tapered portion inside; and
An inward projection provided by pressing and deforming the vicinity of the rear end of the holder from the outside at three locations and projecting inward of the back hole;
And backflow preventing ball ing is inserted into the back hole from the holder or the writing ball and the same kind of material between the rear end of the inner protrusion and the back hole,
A ballpoint pen tip comprising: a rear end crimping portion formed by crimping a rear end portion of the back hole inward.
  A rear end of a spring that is inserted into the back hole and whose tip portion is formed as a pressing rod that presses the writing ball toward the tip is supported by the front end portion of the inward projection. The ball-point pen tip according to claim 1.   3. A ballpoint pen refill having the ballpoint pen tip according to claim 1 or 2 attached to a tip of an ink storage tube for storing ink therein.

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