JP4303353B2 - Writing instrument - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a writing instrument. More specifically, the present invention relates to a writing instrument comprising a front shaft provided with a pen tip at the front end and a cylindrical rear shaft fitted to the rear outer peripheral surface of the front shaft.
[0002]
[Prior art]
Conventionally, Japanese Patent Laid-Open No. 7-117390 relates to a connection structure between a front shaft and a rear shaft for obtaining a strong fixing force between the front shaft and the rear shaft, and is fitted to the front shaft outer peripheral surface and the rear shaft inner peripheral surface, respectively. There is disclosed a configuration in which a plurality of annular convex portions and annular concave portions that form a joint relationship are formed and a fitting portion is provided over the annular convex portion and the annular concave portion.
[0003]
However, even if the conventional connection structure is firmly fixed in the axial direction (drawing direction), it is fixed in the radial direction and the rotational direction due to the manufacturing size variation of the fitting part and the creep change of the fitting part over time. Power tends to relax. That is, at the time of writing use, the rear shaft wobbles or rotates in the radial direction with respect to the front shaft, thereby preventing stable writing use by the user.
[0004]
[Problems to be solved by the invention]
The present invention solves the above-mentioned conventional problems, and the front shaft and the rear shaft are not only firmly fixed in the axial direction but also firmly fixed in the radial direction and the rotational direction. It is intended to provide a writing instrument with a structure.
[0005]
[Means for Solving the Problems]
[1] The present invention comprises a front shaft 2 having a pen tip 21 at the front end, and a cylindrical rear shaft 5 fitted on the outer peripheral surface of the cylindrical insertion portion 3 at the rear of the front shaft 2; Between the outer peripheral surface of the insertion portion 3 and the inner peripheral surface of the rear shaft 5, there is provided a climbing fitting portion 6 composed of an outward projection 61 and an inward projection 62 that fit over each other in the axial direction. A writing instrument 1 in which the front shaft 2 and the rear shaft 5 are connected and fixed, and an outward press-contact portion 71 that presses in a radial direction between the outer peripheral surface of the insertion portion 3 and the inner peripheral surface of the rear shaft 5; While providing the press-fit fitting portion 7 composed of the inward press-fit portion 72, and providing the anti-rotation engaging portion 8 consisting of the outward convex portion 81 and the inward convex portion 82 that are engaged with each other in the rotational direction, It is a requirement that the press-fitting fitting portion 7 and the anti-rotation engagement portion 8 are disposed in the axial direction (Claim 1). To.
[0006]
(Function)
The crossover fitting portion 6 is provided on the outer peripheral surface of the insertion portion 3 formed on the rear portion of the front shaft 2 and on the inner peripheral surface of the rear shaft 5 (for example, an annular protrusion or a distributed protrusion). It consists of inward projections 62 (for example, annular projections or dispersed projections). When the insertion portion 3 of the front shaft 2 is inserted into the rear shaft 5, the outward projection 61 and the inward projection 62 are fitted over each other in the axial direction. Thereby, a strong fixing force in the axial direction between the front shaft 2 and the rear shaft 5 is obtained, and the rear shaft 5 is prevented from falling off from the front shaft 2. In addition, the combination of the outward projection 61 and the inward projection 62 is preferably a combination (for example, a combination of an annular projection and an annular projection, or a combination of an annular projection and a dispersive projection) in a fitting relationship.
[0007]
The pressure contact fitting portion 7 includes an outward pressure contact portion 71 (for example, an annular protrusion, a distributed protrusion, an annular smooth surface, etc.) provided on the outer peripheral surface of the insertion portion 3 of the front shaft 2, and a pressure contact fit with the outward pressure contact portion 71. And an inward pressure contact portion 72 (for example, an annular protrusion, a dispersed protrusion, an annular smooth surface, etc.) provided on the inner peripheral surface of the rear shaft 5. When the insertion portion 3 of the front shaft 2 is inserted into the rear shaft 5, the outward pressure contact portion 71 and the inward pressure contact portion 72 are in radial contact with each other. Shaking of the shaft 5 in the radial direction is suppressed. The combination of the outward pressure contact portion 71 and the inward pressure contact portion 72 is, for example, a combination of an annular protrusion and an annular smooth surface, a combination of a distributed protrusion and an annular smooth surface, or a combination of an annular smooth surface and an annular smooth surface. Can be mentioned.
[0008]
The anti-rotation engaging portion 8 includes an outward convex portion 81 formed on the outer peripheral surface of the insertion portion 3 of the front shaft 2 and an inward convex portion 82 formed on the inner peripheral surface of the rear shaft 5. When the insertion portion 3 of the front shaft 2 is inserted into the rear shaft 5, the outward convex portion 81 and the inward convex portion 82 are engaged with each other in the rotational direction. Relative rotation of the front shaft 2 and the rear shaft 5 is reliably suppressed by the engagement of the inward convex portion 82 and the outward convex portion 81 in the rotational direction.
[0009]
In the present invention, in particular, the over-the-fitting fitting portion 6, the press-fitting fitting portion 7, and the anti-rotation engagement portion 8 are arranged in the axial direction (that is, the front-rear direction). By providing the part 6, the press-fitting fitting part 7, and the anti-rotation engaging part 8 separately at the front and rear positions, the respective functions can be sufficiently exhibited independently.
[0010]
If the pressure contact fitting portion 7 and the anti-rotation engagement portion 8 are provided at a position overlapping in the axial direction, and the structure serves both as an anti-rattle function and an anti-rotation function at the position, a strong anti-rotation engagement is provided. If the outward convex portion 81 and the inward convex portion 82 are protruded greatly in the radial direction in order to obtain, the inner diameter of the rear shaft 5 (the outer diameter of the rear shaft 5 associated therewith) increases, and the rear shaft 5 has an unfavorable appearance. On the contrary, if the outer diameter of the rear shaft 5 is kept slim, the protruding amount of the outward convex portion 81 and the inward convex portion 82 must be set small, and a strong detent Function may not be obtained.
[0011]
[2] In the writing instrument 1 according to the first aspect, the outward protrusion 61 is provided on the front outer peripheral surface of the insertion portion 3, the outward pressure contact portion 71 is provided on the rear outer peripheral surface of the insertion portion 3, and the insertion Preferably, the outward convex portion 81 is provided behind the outward pressure contact portion 71 on the rear outer peripheral surface of the portion 3 (Claim 2).
[0012]
(Function)
By providing the outward projection 61 on the outer peripheral surface of the front portion of the insertion portion 3 and providing the outward pressure contact portion 71 on the rear outer peripheral surface of the insertion portion 3, the overpass fitting portion 6 is press-fit to the outer peripheral surface of the insertion portion 3. They can be provided at positions that are largely separated before and after the joint portion 7. Thereby, wobbling in the radial direction between the front shaft 2 and the rear shaft 5 can be further suppressed.
[0013]
Further, by providing the outward convex portion 81 behind the outward pressure contact portion 71, the amount of engagement between the outward convex portion 81 and the inward convex portion 82 of the anti-rotation engaging portion 8 can be freely set large. If the outward convex portion 81 is provided in front of the outward pressure contact portion 71 contrary to the above-described configuration, the outward convex portion 81 and the inward convex portion 82 are provided if the outer diameter of the rear shaft 5 is limited in appearance. It cannot project greatly, and a sufficient amount of engagement of the detent engagement portion 8 (that is, a sufficient detent effect) cannot be obtained.
[0014]
Further, by providing the crossover fitting portion 6 at the front portion of the insertion portion 3 and the front portion of the rear shaft 5, compared to the case where the crossover fitting portion 6 is provided at the rear portion of the insertion portion 3, Processing is advantageous.
[0015]
[3] In the writing instrument 1 according to claim 2, the insertion portion 3 includes a large diameter portion 31 and a small diameter portion 32 connected to the rear end of the large diameter portion 31, and a rear outer peripheral surface of the large diameter portion 31. The outward pressure contact portion 71 is provided on the outer peripheral surface of the small-diameter portion 32, and the outward convex portion 81 is provided on the outer peripheral surface of the small-diameter portion 32. The front portion of the vertical rib 9 is an inward pressure contact portion 72 for press-fitting with the outward pressure contact portion 71 of the rear outer peripheral surface of the large diameter portion 31, and the rear portion of the vertical rib 9 is the small diameter portion. It is preferable that the inward convex portion 82 is engaged with the outward convex portion 81 on the outer peripheral surface 32 (Claim 3).
[0016]
(Function)
In particular, the rear shaft 5 that is engaged with the outward convex portion 81 in the rotation direction by providing the rear end portion of the insertion portion 3 with the small diameter portion 32 and providing the outward convex portion 81 on the outer peripheral surface of the small diameter portion 32. The rear part of the longitudinal rib 9 on the inner peripheral surface (that is, the inwardly convex part 82) is protruded greatly inward in the radial direction, and the amount of engagement between the outwardly convex part 81 and the inwardly convex part 82 (overlapping dimension in the radial direction). Can be set large. As a result, it is not necessary to increase the inner diameter of the rear shaft 5 (that is, the outer diameter of the rear shaft 5), and the smart appearance of the rear shaft 5 can be maintained.
[0017]
Further, the front portion of the vertical rib 9 serves as an inward pressure contact portion 72 for press fitting, and the rear portion thereof serves as an inward convex portion 82 for engagement. That is, the longitudinal rib 9 integrally forms an inward press contact portion 72 for press contact fitting and an inward convex portion 82 for rotation stop engagement. Therefore, the structure becomes simple and the mold can be easily manufactured.
[0018]
Further, by arranging the vertical ribs 9 on the inner peripheral surface of the rear shaft 5 at equal intervals, the front part of the vertical ribs 9 (that is, the inward pressure contact part 72) can prevent the uneven radial radial rattling. In addition, the rear portion of the vertical rib 9 (that is, the inwardly convex portion 82) eliminates the need to align the rotation direction when the front shaft 2 and the rear shaft 5 are inserted, and the front shaft 2 and the rear shaft 5 are inserted. Assemblability is improved.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
[0020]
1-4 and FIG. 6 show an embodiment of the writing instrument 1 of the present invention. The writing instrument 1 mainly includes a front shaft 2 and a rear shaft 5.
[0021]
(Front shaft)
The front shaft 2 is integrally formed with a grip portion 4 having a pen tip 21 (here, a ballpoint pen tip) attached to a front end thereof and a cylindrical insertion portion 3 continuously provided behind the grip portion 4. It is an injection molded body of synthetic resin. The insertion portion 3 includes a front cylindrical large-diameter portion 31 and a rear-end cylindrical small-diameter portion 32, and has an outer diameter smaller than that of the grip portion 4 as a whole.
[0022]
On the outer peripheral surface of the front portion of the large-diameter portion 31, four dispersive projections arranged at regular intervals are arranged at three locations in the axial direction. Among the three dispersed projections, the two front locations are outward projections 61 for fitting over and the rearmost one location is an outward pressure contact portion 71 for press fitting. Further, two outward convex portions 81 extending in the axial direction are formed on the outer peripheral surface of the small diameter portion 32.
[0023]
(Rear axis)
The rear shaft 5 is a bottomed cylindrical body whose front end is opened and whose rear end is closed, and is formed by injection molding of synthetic resin. On the inner peripheral surface of the front portion of the rear shaft 5 (that is, the inner peripheral surface on the opening side), annular projections are arranged in three axial directions. Among the three annular projections, the two front portions are inward projections 62 for getting over and fitted, and the rearmost one portion is in pressure contact with the rear surface of the outward projection 61 at the intermediate position of the insertion portion 3.
[0024]
Further, eight vertical ribs 9 extending in the axial direction from the bottom surface are arranged on the rear inner peripheral surface (that is, the closed inner peripheral surface) of the rear shaft 5 at equal intervals in a circumferential shape. The vertical rib 9 has an inward pressure contact portion 72 having a large inscribed circle diameter at the front portion and an inward convex portion 82 having a small inscribed circle diameter at the rear portion.
[0025]
(Function)
When the inner peripheral surface of the rear shaft 5 is inserted into the outer peripheral surface of the insertion portion 3 of the front shaft 2 (see FIGS. 1 and 6), the outward projection 61 and the inward projection 62 are fitted over each other, At the same time, an annular smooth surface (that is, the outward pressure contact portion 71) of the rear outer peripheral surface of the large diameter portion 31 of the insertion portion 3 and a front portion (that is, the inward pressure contact portion 72) of the vertical rib 9 on the inner peripheral surface of the rear shaft 5. Is press-fitted in the radial direction (see FIG. 3), and further, the outward convex portion 81 on the outer peripheral surface of the small diameter portion 32 of the insertion portion 3 and the rear portion of the vertical rib 9 on the inner peripheral surface of the rear shaft 5 (that is, inward convex). Part 82) engages in the circumferential direction (see FIG. 4).
[0026]
(Non-rotating engagement part)
As shown in FIG. 4, the eight inward convex portions 82 have a central angle α between adjacent convex portions set to 45 degrees. Further, the center angle β between the convex portions of the two outward convex portions 81 is set to 22.5 degrees. As an engagement form of the inward convex portion 82 and the outward convex portion 81, when one of the inward convex portions 82 is engaged with an engaging concave portion between the two outward convex portions 81 (FIG. 4). Solid line portion), there are cases where the two outward convex portions 81 are engaged with the engagement concave portions between the adjacent inward convex portions 82 (two-dot chain line portions in FIG. 4). Has a detent effect.
[0027]
Further, as shown in FIG. 4, in the anti-rotation engaging portion 8 of the present embodiment, the diameter of the inscribed circle of the inward convex portion 82 on the inner peripheral surface of the rear shaft 5 is outside the small diameter portion 32 of the front shaft 2. It is set slightly larger than the diameter (base circle excluding the outward convex portion 81), and when the front shaft 2 and the rear shaft 5 are fitted, the outer peripheral surface of the small diameter portion 32 and the rear portion of the inward convex portion 82 are not in contact with each other. Is in a state.
[0028]
In addition to the engagement form of FIG. 4, as shown in FIG. 5, the central angle α between adjacent convex portions of the eight inward convex portions 82 is set to 45 degrees, while the two outward directions The center angle β between the convex portions of the convex portion 81 may be set to 157.5 degrees. Thereby, the same anti-rotation effect as FIG. 4 is acquired. When the central angle α of the inward convex portion 82 is 45 degrees, the central angle β of the outward convex portion 81 is 67.5 degrees, or 112. Even at 5 degrees, the same effect as in FIG. 4 can be obtained.
[0029]
Note that the center angle β of the outward convex portion 81 can be appropriately configured in addition to the above-described combinations as long as the front shaft 2 and the rear shaft 5 can be prevented from rotating.
[0030]
(Other)
As the type of the front shaft 2 of the writing instrument 1 of the present invention, for example, (a) an ink tank that directly stores ink is formed in the rear portion of the front shaft 2, and the ink tank is formed in the front portion of the front shaft 2. An ink adjusting member (for example, a comb-like member) that temporarily holds overflow ink in response to a change in internal pressure of the ink, or (b) the ink is directly stored in the front shaft 2 and the rear end of the ink And the like provided with a follower (e.g., a grease, an elastic body, a solid, etc.) that moves forward with ink consumption.
[0031]
Particularly, in the case of the type (a), when an ink tank is formed in the insertion portion 3 of the front shaft 2 and the inner peripheral surface of the rear shaft 5 is fitted to the outer peripheral surface of the insertion portion 3, as shown in FIG. An annular gap (heat insulating space) can be formed between the inner surface of the rear shaft 5 and the outer surface of the front shaft 2, preventing air expansion in the ink tank due to the body temperature of the hand, and preventing leakage of ink from the pen tip 21.
[0032]
In addition to the ballpoint pen tip, the pen tip 21 of the present invention includes, for example, a fiber pen body, a pipe-shaped pen body, a metal plate pen body for a fountain pen, a brush pen body, a porous pen body, a plastic extrusion pen body, and the like. Can be mentioned.
[0033]
【The invention's effect】
According to the first to third aspects of the invention, the front shaft and the rear shaft are firmly fixed in the axial direction, and the front shaft and the rear shaft are also firmly fixed in the radial direction and the rotational direction. A structure can be provided.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.
FIG. 2 is an enlarged view of a part S in FIG.
FIG. 3 is an enlarged cross-sectional view taken along line AA in FIG.
4 is an enlarged sectional view taken along line BB in FIG. 1;
FIG. 5 is a cross-sectional view showing a modification of the detent engagement portion.
6 is a view showing a front shaft and a rear shaft before insertion assembly of FIG. 1; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Writing instrument 2 Front shaft 21 Pen tip 3 Insertion part 31 Large diameter part 32 Small diameter part 4 Gripping part 5 Rear shaft 6 Overcoming fitting part 61 Outward protrusion 62 Inward protrusion 7 Pressing fitting part 71 Outward pressing part 72 Inward pressure contacting part 8 Stop engaging portion 81 Outward convex portion 82 Inward convex portion 9 Vertical rib α Center angle of inward convex portion β Center angle of outward convex portion

Claims (3)

From the front shaft (2) having a pen tip (21) at the front end, and the cylindrical rear shaft (5) fitted to the outer peripheral surface of the cylindrical insertion portion (3) at the rear of the front shaft (2) And an over-fitting fitting portion composed of an outward projection (61) and an inward projection (62) that are fitted over each other in the axial direction between the outer peripheral surface of the insertion portion (3) and the inner peripheral surface of the rear shaft (5). A writing instrument provided with (6), wherein the front shaft (2) and the rear shaft (5) are connected and fixed by the crossover fitting portion (6), the outer peripheral surface of the insertion portion (3) and the rear shaft (5) A press-fitting fitting portion (7) including an outward press-contact portion (71) and an inward press-contact portion (72) that are in pressure contact with each other in the radial direction is provided between the inner peripheral surfaces and is engaged with each other in the rotational direction. An anti-rotation engaging portion (8) comprising an outward convex portion (81) and an inward convex portion (82) is provided, and the overcoming fitting portion (6) and the press-fit fit It said detent engaging portion and parts (7) (8) and the writing instrument being characterized in that disposed in the axial direction. The outward projection (61) is provided on the front outer peripheral surface of the insertion portion (3), the outward pressure contact portion (71) is provided on the rear outer peripheral surface of the insertion portion (3), and the insertion portion (3) The writing instrument according to claim 1, wherein the outward convex portion (81) is provided behind the outward pressure contact portion (71) on the rear outer peripheral surface of the rear portion. The insertion portion (3) includes a large diameter portion (31) and a small diameter portion (32) connected to the rear end of the large diameter portion (31), and the insertion portion (3) is provided on the outer peripheral surface of the rear portion of the large diameter portion (31). A plurality of longitudinal ribs are provided on the outer peripheral surface of the small-diameter portion (32), while the outward convex portion (81) is provided on the outer peripheral surface of the small-diameter portion (32), and on the inner peripheral surface of the rear shaft (5). (9) are provided at equal intervals, and an inward pressure contact portion (72) that press-fits the front portion of the vertical rib (9) with the outward pressure contact portion (71) of the rear outer peripheral surface of the large diameter portion (31). The writing tool according to claim 2, wherein the rear portion of the vertical rib (9) is an inward convex portion (82) engaged with the outward convex portion (81) of the outer peripheral surface of the small diameter portion (32).

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