JP2003054182A - Barrel of writing utensil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the barrel of a writing utensil, which is formed by combining a plurality of constitutional members composing the barrel of the writing utensil through a screw fitting, and in which the breakage of the barrel hardly happens during a mechanical stoppage and assembling through the trouble of the screw fitting in the barrel constitutional members of the writing utensil due to the vibration of a machine, the scatter in a product or the like and which is suitable for the mechanical assembling by a method wherein the external screw part is favorable led in the internal screw part in the barrel screw fitting. SOLUTION: On a plurality of the synthetic resin constitutional members formed by molds composing the barrel of the writing utensil, each has external screw parts or internal screw parts. The barrel of the writing utensil is formed by connecting a plurality of constitutional members through the screw fittings between the external screw parts and the internal screw part under the condition that the tip surface of the screw thread of the external screw part and/or the tip surface of the screw thread of the internal screw part are inclined to the valley part side between the screw threads in the direction along the axis center line.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a writing instrument barrel connected with a plurality of components constituting a writing instrument barrel by screw fitting. 2. Description of the Related Art Conventionally, a screw portion (for example, a male screw portion) formed on a front shaft and a screw portion (for example, a female screw portion) formed on a rear shaft constituting a barrel of a writing instrument are screw-fitted. Description of the Related Art Shaft barrels for writing implements, such as those for coupling, are well known in the art for connecting the barrel components of the writing implement to screw fittings. In addition, mass production is desired for writing implements using the barrel of such a writing implement, especially for low-priced writing implements, and it is common to carry out mechanical assembly in consideration of an increase in the number of productions. There is a need for a writing instrument barrel suitable for a good mechanical assembly. In a method of assembling a barrel of a writing instrument, if it is manually assembled, it is possible to visually confirm the positional relationship between a male screw portion and a female screw portion and adjust the initial screw fitting, as described above. A machine assembly suitable for mass production is desired.In the case of a machine assembly, for example, when a rear shaft is brought into contact with a fixedly held front shaft and a screw is fitted by rotating the rear shaft. , The front shaft and the rear shaft are misaligned due to machine vibration, product variation, etc., and the initial screw fitting does not work well. In addition, there is a problem that not only does the machine stop, the working efficiency is remarkably reduced, and if the rotational force is continuously applied to the rear shaft in this state, the front shaft and the rear shaft are damaged. [0004] By the way, as shown in FIGS. 7 to 10, the shape of the threaded portion of the shaft barrel of the conventional writing instrument is such that both the male threaded portion 35 and the female threaded portion 33 have a screw thread. 3
Tip surfaces 35b, 33b of 5a, 33a are formed parallel to each other along the axis. For this reason, in the initial screw fitting in which the distal end surface 35b of the thread of the male screw portion enters the female screw portion 33, the distal end surface 35b of the male screw portion collides with the distal end surface 33b of the female screw portion. It turned out that. [0005] As a result of the study of the screw fitting by the present inventors, it is important to securely carry out the initial screw fitting. Focusing on the fact that screw fitting can be easily performed only by applying a rotating force up to this point, the present invention has been achieved. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has been made in consideration of the above circumstances. Improve the connection between the thread and female thread,
It is intended to provide a writing instrument barrel suitable for machine assembly, in which the stoppage of the machine due to the failure of screw fitting of the barrel component of the writing instrument or the damage of the barrel during assembly is unlikely to occur due to mechanical vibration or product variation. is there. According to the present invention, a male screw portion or a female screw portion is formed on each of a plurality of constituent members constituting a barrel of a synthetic resin writing instrument formed by a mold. And a shaft cylinder of a writing instrument formed by connecting a plurality of constituent members by screw fitting of a male screw portion and a female screw portion, wherein a tip surface of a screw thread of the male screw portion and / or a screw thread of the female screw portion are formed. The tip surface is inclined toward the root between the threads in a direction along the axis. [0008] The barrel of the writing instrument of the present invention refers to a barrel containing a refill filled with ink or a cap. The constituent members that constitute the barrel of the writing instrument, for example, refer to members such as a base, a barrel body, and a tail cap in the former, and refer to members such as a head cap and a cap body in the latter, and constitute a so-called barrel or cap. It is a conventionally known member. Embodiments of the present invention will be described with reference to the drawings. The barrel 1 of the writing instrument according to the first embodiment shown in FIGS. 1 to 5 has a female thread 3 provided inside the rear end of the barrel main body 2. The barrel body 2 is obtained by simultaneously molding the female screw portion 3 by injection molding using a polycarbonate resin. The cap 4 has a male screw portion 5 and a clip 12 integrally provided on the rear outer peripheral surface. Cap 4
Similarly, the male screw portion 5 is formed by injection molding using a polycarbonate resin in the same manner as the barrel body 2. The female cylinder 3 of the barrel main body 2 and the male thread 5 of the crown 4 are screw-fitted to obtain the barrel 1 of a writing implement. At this time, the distal end face 3b of the thread 3a obtained by forming the female screw portion 3 in the barrel body 2 is not provided in parallel with the direction along the axis as shown in FIG. It is provided so as to be inclined toward the valley 3c between the thread 3a of the female thread in the direction along the axis. Similarly, the distal end face 5b of the thread 5a of the male screw portion 5 formed on the crown 4 is provided so as to be inclined toward the valley 5c between the threads 5a of the male screw portion 5 in a direction along the axis. By tilting the tip surfaces 3b and 5b, the male screw portion 5 is formed.
When the thread enters the female screw portion 3, the thread 3a of the female screw portion 3
Of the screw thread 5a of the male screw portion 5
The portion that comes into contact with the vehicle is reduced, so that the vehicle can easily enter. Further, even if the distal end face 5b of the thread 5a of the male thread 5 abuts against the distal end face 3b of the thread 3a of the female thread 3, it is inclined toward the valley in the direction along the axis. As a result, the screw advances as a result in the inclined direction (entering direction), so that the initial screw fitting can be easily performed. For this reason, although not shown, even in a mechanical assembly in which the barrel 2 is fixedly held and the head crown 4 is rotated while being screw-fitted to the barrel 2, the shaft may be displaced due to machine vibration, product variation, or the like. The problem of screw fitting between the cylinder main body 2 and the crown 4 hardly occurs. Further, if the tip surface 5b of the screw thread of the male screw portion 5 and the tip surface 3b of the screw thread of the female screw portion 3 are inclined with respect to the radial direction, the screw of the male screw portion at the time of screw fitting. Mountain 5a
However, since a force is applied in the direction in which the female thread 3a rides on the thread 3a, the initial screw fitting may not be successful, so the distal end face 5b of the thread of the male thread 5 and the female thread 3 It is preferable that the tip surface 3b of the screw thread is formed in a normal direction to the circumferential direction. FIG. 5 shows a ball-point pen refill 7 containing ink for a writing implement (not shown) in a barrel 1 of a writing implement according to the first embodiment, which is urged by a coil spring 6 toward the rear end of the barrel. FIG. 4 is a diagram illustrating a knock-type ballpoint pen provided with a retractable mechanism including a rotating cam 15 in a crown 4. This retracting mechanism is conventionally known, and when briefly described, the rotating cam 1 is mounted on the inner wall surface of the crown 4.
A cam groove (not shown) for slidingly guiding and rotating the front and rear 5 is formed, and a rotary cam 15 is engaged with the cam groove and disposed. At the rear end of the rotary cam 15, a knock body 14 having a cam portion for sliding the rotary cam 15 to impart rotation is provided at the front end. The rear end of the knock body 14 is the rear end of the crown 4. This is a structure arranged so as to protrude outward from the opening 4a. Reference numeral 13 in the drawing denotes a grip formed of a soft material attached to the grip portion of the barrel body 2. In the shaft barrel of the writing instrument of the present invention, the tip surface of the thread of the male thread and / or the tip of the thread of the female thread is inclined toward the valley in the direction along the axis. As in the first embodiment, the entire distal end surface may be inclined as described above, or as shown in FIG. 6, the distal end surface 25b of the thread 25a of the external thread portion 25 of the crown 24 may be used. Part may be inclined. However, since the distal end surface is entirely inclined in the axial direction, when the male screw portion enters the female screw portion, the portion where the screw thread of the male screw portion and the screw thread of the female screw portion are in contact decreases more. preferable. In addition, it is preferable that the inclination angle α of the inclined surface be as acute as possible, because the resistance at the time of entry is reduced. Further, in the present invention, the inclination is made in the direction along the axis toward the valley side between the thread and the thread, but the inclination in the opposite direction should not be formed because the male thread is not in the direction to enter the female thread. Good. In the present embodiment, the tip surface of the thread of the male thread and / or the tip surface of the thread of the female thread are inclined. Since the number of contact portions is reduced, the initial screw fitting becomes easy. However, it is preferable to incline both of them because the number of contact portions at the time of entry is reduced. In this embodiment, polycarbonate is used for the barrel member for convenience. However, the present invention is not limited to this. For example, polyethylene terephthalate, AS resin and the like are known as barrel members for writing instruments. Synthetic resin can be appropriately selected and used. Further, the barrel of the writing implement is a barrel of a knock type ball-point pen using a rotary cam, but is not limited to this. Can be used in fitting. Also, among the members constituting the barrel of the writing implement, those integrally formed with the clip have a poor weight balance because the clip forming direction is protruded, and the construction of the barrel of the writing implement is poor due to mechanical vibrations and product variations. The effect of the present invention is particularly remarkable since defects in screw fitting of members are easily generated. The present invention has the above-described configuration,
In the barrel of a writing instrument, which is formed by connecting a plurality of components constituting the barrel of a writing instrument by screw fitting, the sticking of the male screw portion and the female screw portion in the initial screw fitting is improved, and the vibration of the machine and the product Due to the above-mentioned variation, it is possible to provide a writing instrument barrel that is suitable for machine assembly, in which the stopping of the machine due to a screw fitting failure of the barrel component of the writing instrument and the damage of the barrel during assembly are unlikely to occur.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a female screw portion and an external view of a male screw portion for explaining screw fitting in the 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 partially omitted in FIG. 1; FIG. 4 is a schematic view for explaining an initial screw fitting of 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 a female screw portion and an external view of a male screw portion for explaining conventional screw fitting. FIG. 8 is a perspective view of a rear shaft partially omitted in FIG. 7; FIG. 9 is a schematic view for explaining a conventional initial screw fitting. [Description of Signs] 1 Shaft tube 2, 32 Front shaft 3, 33 Female thread portion 3a, 33a Female thread portion 3b, 33b Female screw thread distal end face 3c, 33c Female thread valley portion 4, 24 , 34 Crown 5, 25, 35 Male thread 5a, 25a, 35a Male thread 5b, 25b, 35b Male thread thread tip 5c, 25c, 35c Male thread valley 6 Coil spring 7 Ballpoint pen refill 8 Ink storage cylinder 9 Tip holder 10 Ballpoint pen tip 11 Tail plug 12 Clip 13 Grip 14 Knock body 15 Rotating cam

Claims (1)

Claims: 1. A plurality of constituent members, each having a male screw portion or a female screw portion formed on each of a plurality of constituent members constituting a barrel of a synthetic resin writing instrument formed by a mold. Are connected by screw fitting of a male screw part and a female screw part, and the tip end face of the screw thread of the male screw part and / or the tip face of the screw thread of the female screw part are A shaft barrel for a writing implement, characterized by being inclined toward the valley between the threads in a direction along the center.