JP4822309B2 - Writing instrument shaft - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shaft tube of a writing tool formed by connecting a plurality of constituent members constituting the shaft tube of a writing tool by screw fitting.
[0002]
[Prior art]
Conventionally, the shaft of a writing instrument, such as a structure in which a screw part (for example, a male thread part) formed on a front shaft and a screw part (for example, a female thread part) formed on a rear shaft are connected by screw fitting. A shaft cylinder of a writing instrument having a structure in which a cylinder constituent member is connected to a screw fitting is well known. In addition, mass production is desired for writing instruments using a shaft of such a writing instrument, in particular, low-priced writing instruments, and it is common to assemble machines in consideration of an increase in the number of production. There is a demand for a writing instrument shaft suitable for a good machine assembly.
[0003]
In the method of assembling the writing cylinder, it is possible to visually confirm the positional relationship between the male screw part and the female screw part and adjust the initial screw fitting if it is a manual assembly. In the case of a machine assembly, for example, when the rear shaft is brought into contact with the fixedly held front shaft and the rear shaft is rotated to perform screw fitting, Misalignment between the front and rear shafts occurs due to vibration, product variations, etc., and the initial screw fitting does not work well, and the screw fitting does not end even if a force is applied by the machine, and the machine stops. In this state, there is a problem that the front shaft and the rear shaft are damaged if the rotational force is continuously applied to the rear shaft in this state.
[0004]
[Problems to be solved by the invention]
By the way, as shown in FIGS. 7 to 10, the shape of the screw portion in the shaft cylinder of the conventional writing instrument is such that both the male screw portion 35 and the female screw portion 33 have the tip surfaces 35 b and 33 b of the screw threads 35 a and 33 a as the axis. Are formed parallel to each other. Therefore, in the initial screw fitting in which the front end surface 35b of the thread of the male screw portion enters the female screw portion 33, the front end surface 35b of the male screw portion collides with the front end surface 33b of the female screw portion. I found it difficult.
[0005]
As a result of examining the screw fitting, the present inventors have confirmed that it is important to surely perform the initial screw fitting. If the initial screw fitting is surely performed, the rotational force until the screw fitting is finished thereafter. Focusing on the fact that it is possible to easily perform screw fitting only by adding, the present invention has been achieved.
[0006]
The present invention has been made in view of these facts, and in a writing tool shaft tube in which a plurality of constituent members constituting the writing tool shaft tube are screw-fitted and connected, the male screw portion in the initial screw fitting and Suitable for machine assembly because the female screw part is improved and the shaft cylinder is difficult to stop due to the screw fitting failure of the shaft cylinder component of the writing instrument due to machine vibration or product variation. A shaft of a writing instrument is provided.
[0007]
[Means for Solving the Problems]
The present invention forms a male screw part or a female screw part in each of a plurality of constituent members constituting a shaft cylinder of a writing instrument made of a synthetic resin formed by a mold, and the plurality of constituent members are a male screw part and a female screw. A shaft cylinder of a writing instrument that is connected by screw fitting of the portion, wherein the tip surface of the thread of the male screw portion is directed to the tip surface of the screw thread of the male screw portion with respect to the direction along the axis. The threaded portion of the male threaded portion that is connected and the valley side between the threads, and inclined from the distal end surface of the male threaded portion in the thread forming direction, and / or the distal end surface of the threaded portion of the female threaded portion is axially centered. , Along the trough side between the thread of the female thread and the thread connected to the tip of the thread of the female thread, and in the direction of thread formation from the tip of the female thread. Inclined .
[0008]
The shaft tube of the writing instrument of the present invention refers to a shaft tube containing a refill filled with ink or a cap. The components constituting the shaft cylinder of the writing instrument refer to members such as a base, a shaft cylinder main body, and a tail crown in the former, and members such as a head crown and a cap main body in the latter, for example, so-called shaft cylinders and caps. It is a conventionally known member.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. The shaft cylinder 1 of the writing instrument according to the first embodiment shown in FIGS. 1 to 5 has a shape in which a female screw portion 3 is provided inside the rear end of the shaft cylinder main body 2. The shaft tube main body 2 is obtained by simultaneously molding the female screw portion 3 by injection molding using a polycarbonate resin.
[0010]
The head crown 4 has a male screw portion 5 and a clip 12 is integrally provided on the rear outer peripheral surface. The head crown 4 is also obtained by simultaneously molding the male screw portion 5 by injection molding using polycarbonate resin in the same manner as the shaft body 2.
[0011]
The shaft cylinder 1 of the writing instrument is obtained by screw-fitting the female thread portion 3 of the shaft barrel body 2 and the male thread portion 5 of the head crown 4. At this time, the tip end surface 3b of the thread 3a obtained by forming a female threaded portion 3 to the barrel body 2, as shown in FIG. 1, not provided in parallel with the direction along the axis, the axis The tip surface 3b of the thread 3a of the female thread portion is provided to be inclined toward the valley 3c side between the thread 3a with respect to the direction along the center. Similarly, the front end surface 5b of the thread 5a of the male thread 5 formed on the head crown 4 is inclined toward the valley 5c side between the threads 5a of the male thread 5 with respect to the direction along the axis. Provide. By inclining the tip surfaces 3b and 5b, when the male screw portion 5 enters the female screw portion 3, the tip surface 3b of the screw thread 3a of the female screw portion 3 and the screw thread 5a of the male screw portion 5 are formed. Since the resistance of the portion in contact with the front end surface 5b is reduced, it becomes easier to enter. The end face 5b of the thread 5a of the male screw portion 5 is also in contact with the tip end surface 3b of the thread 3a of the female screw portion 3, is inclined valley side with respect to the direction along the axis As a result, since it progresses in an inclination direction (approach direction) as a result, initial screw fitting can be easily performed. Therefore, although not shown in the figure, the shaft assembly 2 is fixed and held, and even if it is a mechanical assembly that is screw-fitted to the shaft barrel body 2 while rotating the crown 4, the shaft assembly is affected by machine vibration or product variations. Problems with screw fitting between the tube body 2 and the crown 4 are unlikely to occur.
[0012]
Further, when the front end surface 5b of the screw thread of the male screw part 5 and the front end face 3b of the screw thread of the female screw part 3 are inclined with respect to the radial direction, the screw thread 5a of the male screw part is formed during screw fitting. Since a force is applied in the direction of climbing on the thread 3a of the female screw portion 3, the initial screw fitting may not be successful, so that the front end surface 5b of the thread of the male screw portion 5 and the screw of the female screw portion 3 The tip end surface 3b of the mountain is preferably formed in a normal line with respect to the direction along the axis .
[0013]
FIG. 5 shows that a ballpoint pen refill 7 containing writing tool ink (not shown) is urged by a coil spring 6 toward the rear end of the shaft cylinder in the shaft cylinder 1 of the writing instrument according to the first embodiment. FIG. 5 is a view showing a knock type ballpoint pen in which a retracting mechanism including a rotating cam 15 is mounted in the crown 4. This intruding mechanism is known in the art. Briefly, a cam groove (not shown) is formed on the inner wall surface of the crown 4 for sliding and rotating the rotating cam 15 back and forth. The rotating cam 15 is engaged with the cam groove. At the rear end of the rotary cam 15, a knock body 14 having a cam portion for sliding and rotating the rotary cam 15 is provided at the front end, and the rear end portion of the knock body 14 is the rear end of the crown 4. It is the structure arrange | positioned in the state protruded outward from the opening part 4a. Note that reference numeral 13 in the drawing denotes a grip formed of a soft material attached to a grip portion of the shaft tube main body 2.
[0014]
Barrel of the writing instrument of the present invention, the front end surface and / or the distal end surface of the thread of the female screw portion of the screw thread of the male threaded portion, but is inclined to the valley side in a direction along the axis, the first As in the embodiment, all of the front end surface may be inclined as described above, and as shown in FIG. 6, one end surface 25b of the thread 25a of the male screw portion 25 of the crown 24 is shown. The part may be inclined. However, since the tip end surface is inclined in the axial direction, when the male screw part enters the female screw part, the portion where the screw thread of the male screw part and the screw thread of the female screw part come into contact is further reduced. preferable. Moreover, since the resistance at the time of approach will decrease, so that the inclination | tilt angle (alpha) of an inclined surface becomes an acute angle is preferable. Furthermore, in the present invention, the screw thread is inclined toward the valley between the screw threads in the direction along the axial center, but the inclination in the opposite direction is not formed because the male screw part does not enter the female screw part. Good.
[0015]
In the present embodiment, the front end surface of the thread of the male screw portion and / or the front end surface of the screw thread of the female screw portion are inclined, but if at least one of them is inclined, the contact portion at the time of entry is Since it decreases, the initial screw fitting becomes easy, but it is preferable to incline both because the contact portion at the time of entry becomes smaller.
[0016]
Further, in this embodiment, for convenience, polycarbonate is used for the shaft tube constituent member, but the present invention is not limited to this, and synthetic materials conventionally known as shaft tube constituent members for writing instruments such as polyethylene terephthalate and AS resin are used. A resin can be appropriately selected and used.
[0017]
In addition, the shaft cylinder of the writing instrument is a knock-type ballpoint pen with a rotating cam, but the invention is not limited to this. Can be used. Also, among the members that make up the writing tube shaft, those with the clip formed integrally project the clip forming direction, so the weight balance is bad and due to machine vibration, product variations, etc., the writing tube shaft configuration The effect of the invention is particularly remarkable because the problem of screw fitting of members is likely to occur.
[0018]
【The invention's effect】
Since the present invention has the above-described configuration, the male screw part and the female screw part in the initial screw fitting in the shaft cylinder of the writing tool formed by screw-fitting and connecting a plurality of constituent members constituting the shaft cylinder of the writing tool. The writing tool shaft is suitable for mechanical assembly because it is less likely to cause machine stoppage or damage to the shaft tube during assembly due to screw fitting failure of the writing tube shaft component due to machine vibration or product variations. A cylinder could be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an internal thread portion and an external view of an external thread portion for illustrating screw fitting in a first embodiment of the present invention.
FIG. 2 is an enlarged view of a main part in FIG.
FIG. 3 is a perspective view of a rear shaft with a part omitted in FIG. 1;
FIG. 4 is a schematic view for explaining initial screw fitting according to the present invention.
FIG. 5 is a longitudinal sectional view showing an example of a writing instrument to which the first embodiment is applied.
FIG. 6 is a modification of the first embodiment.
FIG. 7 is a cross-sectional view of an internal thread portion and an external view of an external thread portion for explaining conventional screw fitting.
8 is a perspective view of the rear shaft with a part omitted in FIG. 7;
FIG. 9 is a schematic view for explaining a conventional initial screw fitting.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Writing cylinder 2 and 32 Front shaft 3 and 33 Female thread part 3a and 33a Female thread part thread 3b and 33b Female thread part thread end face 3c and 33c Female thread part valley part 4, 24 and 34 Head crown 5 , 25, 35 Male thread 5a, 25a, 35a Male thread thread 5b, 25b, 35b Male thread thread tip 5c, 25c, 35c Male thread valley 6 Coil spring 7 Ball pen refill 8 Ink receiving cylinder 9 Tip holder 10 Ballpoint pen tip 11 Tail plug 12 Clip 13 Grip 14 Knock body 15 Rotating cam

Claims (1)

A male screw part or a female screw part is formed in each of a plurality of constituent members constituting a shaft cylinder of a writing instrument made of a synthetic resin formed by a mold, and the plurality of constituent members are screwed into the male screw part and the female screw part. A shaft of a writing instrument that is connected together , wherein the male threaded portion is connected to the threaded tip surface of the male threaded portion in a direction along the axis. A direction along the axial center of the threaded portion of the threaded portion and the valley side between the threaded portions and inclined from the leading end surface of the male threaded portion to the threading direction and / or the threaded tip surface of the female threaded portion In contrast, the screw thread of the female screw part connected to the tip surface of the screw thread of the female screw part and a trough side between the screw threads, and inclined from the tip surface of the female screw part in the thread forming direction. Characteristic writing instrument shaft.

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