JP4829752B2 - Intrusive writing instrument - Google Patents

Description

  The present invention relates to a retractable writing instrument in which a writing tip of a refill can be protruded from a front opening, and more particularly to a structure of a front opening and a refill.

It is well known that a writing tip of a refill provided in a shaft cylinder is projected and retracted from a front end of a writing tool front end by a sliding pusher or a knock mechanism.
For example, as shown in Patent Document 1 by the present applicant, a multi-color writing tool (composite writing tool) that switches a plurality of colors of refills in and out by switching a pusher in the vicinity of the rear end of the shaft cylinder, As described above, there is a writing instrument in which a knock part is provided in addition to the presser so that the lead operation of the refill for the mechanical pencil can be performed.

Thus, in the configuration where the writing tip of the refill appears and disappears, the refill collides with the inner peripheral surface of the tip when projecting the refill, or the inner peripheral surface of the front end and the shaft tube with the refill stored in the shaft tube May come into contact with the inner surface.
As a result, there is a problem that an unpleasant sound due to a collision or contact occurs, and there is a problem that the writing tip is damaged and the aesthetic appearance is deteriorated or a malfunction is caused.

As a related technique, in the technique disclosed in Patent Document 3, in the composite writing instrument in which the writing portion of the writing body is projected and retracted from the tip of the shaft tube, at least the front portion of the shaft tube is formed of metal, and the inner surface of the metal portion shaft tube It is proposed to form a resin layer.
As an effect of the present technology, even if the writing instrument is mistakenly dropped on the ground or the like, the pen tip of the ballpoint pen can be prevented from being crushed so that no ink leakage occurs.

If the resin layer is formed on the inner surface of the metal part shaft cylinder in this way, damage to the pen tip of the ballpoint pen can be prevented, which can be said to be a technique for removing the cause of the malfunction described above.
In the present technology, the shaft tube itself is made of metal, and a resin layer is formed in the entire metal portion shaft tube. In the configuration in which the shaft tube is formed integrally with the tip as disclosed in this document, it is not so difficult to form the resin layer in the shaft tube.

On the other hand, a writing instrument is also known, which consists of a tip and a shaft that are separate from each other, and is assembled by attaching the tip to the shaft, and this configuration improves the aesthetics of the appearance, simplifies the manufacturing process, and maintains the refill. This contributes to the improvement of performance.
In such a writing instrument, the technique in which the front end and the shaft cylinder disclosed in Patent Document 3 are integrally formed cannot be applied as they are, and a plurality of problems remain.
That is, this document takes a configuration in which the resin layer is formed simultaneously on the integrated front end and the shaft tube, but when the front end and the shaft tube are formed separately, the resin layer is not formed after assembly. In addition, if the resin layer is formed, the front end and the shaft tube are fixed, so that the front end cannot be separated from the shaft tube.

In addition, when the resin layer is formed on the inner periphery of the tip or shaft first, the resin layers interfere with each other during assembly of the tip and shaft, or the resin layer is caught in the attachment site, and the appearance is impaired. When the front end is screwed into the shaft tube at the time of attachment, there is a problem that the resin layers are rubbed and peeled off with rotation.
When the resin layer is formed on both, the assembly process becomes complicated, leading to an increase in manufacturing cost.

Furthermore, there are the following problems.
That is, if the tip is easily dropped after the tip is attached to the shaft tube, the tip cannot be properly supported by the tip of the refill writing tip, and it takes time and effort to attach the tip again.
On the other hand, conventionally, a method of adhering the attachment portion has been taken, but when the tip opening is configured to be detachable, a simple and effective method for preventing loose attachment has not been proposed.

By the way, in the retractable writing instrument, the refill slides back and forth so that it is arranged with a relatively large margin in the shaft cylinder. Conventionally, the refill vibrates and comes into contact with the inner periphery of the shaft cylinder and other refills. Has occurred.
In particular, writing instruments having high added value are required to prevent such contact sounds, but no effective method has been proposed.

  For example, Patent Document 4 discloses a configuration in which an O-ring is provided at the tip position as a technique for preventing the shake of the writing tip portion. It does not realize the prevention of sound when the refill is vibrated.

Japanese Patent No. 3168200 JP 2003-39888 JP 2001-63283 A Japanese Utility Model Publication No. 5-85683

  The present invention was created in view of the above-described problems of the prior art, and is a retractable writing instrument that allows the writing tip of the refill to protrude from the tip attached to the front end of the shaft cylinder. An object of the present invention is to provide a technique for preventing the writing tip from being damaged due to interference with the inner periphery of the tip when the sword appears and causing unpleasant noise.

  At that time, the assemblability of the tip and the shaft tube is good, and a structure in which the tip is not easily detached from the shaft tube is provided. Further, the present invention provides a technique for preventing not only the refill and the inner periphery of the front opening but also the contact sound and damage between the refills and between the refill and the shaft tube.

In order to solve the above problems, the present invention uses the following means.
That is, the invention described in claim 1 provides a retractable writing instrument that includes one or a plurality of refills in the shaft cylinder, and allows the writing tip of the refill to be protruded and retracted from a front opening attached to the front end of the shaft cylinder. It is.
In the retractable writing instrument, a resin coating for covering the inner peripheral surface of the tip is attached, and the resin coating is extended to at least a portion near the front end of the inner peripheral surface of the shaft cylinder.

In the present invention, the front end and the shaft tube may be configured separately, and the front end may be attached to the front end of the shaft tube by any one of screwing, fitting, bonding, or a combination of two or more.
As the refill provided in the present invention, any refill such as a ballpoint pen refill, a mechanical pencil refill, a marker refill, and the like can be used.

  Arbitrary synthetic resin and natural resin can be used for the resin coating, but PP (polypropylene), POM (polyoxymethylene), PE (polyethylene), which has relatively high hardness in the configuration using the mechanical pencil refill, It is preferable to use a synthetic resin such as ABS. In other configurations, for example, a thermoplastic elastomer resin can be used.

  The retractable writing instrument according to claim 2 is characterized in that a locking portion for locking at least an axial displacement of the resin coating is formed in the tip. The locking portion may be configured by refraction in the axial direction in the vicinity of the tip of the front end where the writing tip portion appears and disappears, and the tip of the resin coating may be engaged and locked with the bending portion. .

  The retractable writing instrument according to claim 3 is characterized in that, in the vicinity of the front end of the inner peripheral surface of the shaft cylinder of the resin coating, a convex portion that comes into contact with the inner peripheral surface of the shaft cylinder is provided. .

  The retractable writing instrument according to claim 4 is characterized in that the convex portion provided in claim 2 is formed by a gate mark used when molding the resin coating.

The retractable writing instrument according to claim 5 is characterized in that an elastic annular body having elasticity is disposed on the outer periphery of the refill.
In the configuration in which at least one of the refills included in the writing instrument of the present invention is a mechanical pencil refill, the elastic annular body can be particularly provided in the mechanical pencil refill.

Since the present invention is configured as described above, the following operational effects can be obtained.
According to the first aspect of the present invention, by covering not only the inner peripheral surface of the front opening but also the vicinity of the front end of the shaft tube with the resin coating, a portion where the refill can contact when the refill protrudes is necessary and Since it can be sufficiently protected, it is possible to effectively prevent damage to the writing tip and generation of unpleasant noise with a minimum amount of material.

In addition, while extending the resin cover to the vicinity of the front end of the shaft tube, it is not necessary to form the resin cover on the shaft tube side, so the resin coating does not interfere with each other and has good assemblability. Contributes to a simple manufacturing method.
Furthermore, the extended resin coating can generate appropriate friction with the shaft cylinder, so that loosening of the attachment can be prevented, contributing to a retractable writing instrument in which the tip is loosened and is not easily dropped off.

  According to the second aspect of the present invention, since the front end can lock the resin cover, the resin cover is not exposed from the hole where the writing tip portion appears and is not exposed to the writing tip portion. Interference and appearance can be prevented from being damaged.

  According to the third aspect of the present invention, by providing a convex portion in contact with the inner peripheral surface of the shaft cylinder in the vicinity of the front end of the inner peripheral surface of the shaft cylinder in the resin coating, the convex portion and the inner periphery of the shaft cylinder are provided. Since a good contact pressure can be maintained with the surface, it is possible to provide a retractable writing instrument in which the tip is not loosened or is difficult to drop off.

  According to the invention described in claim 4, since the gate mark used when the resin coating is injection-molded can be used, there is no need to separately form a convex portion. In addition, the step of removing the gate trace can be omitted, contributing to simplification of the molding die and the manufacturing process, and the effect of the convex portion.

  According to the invention described in claim 5, by disposing the elastic annular body on the outer periphery of the refill, the elastic annular body acts as a buffer material with respect to other refills and the inner peripheral surface of the shaft cylinder, thereby preventing contact noise. Contributes to the prevention of damage such as refills.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan sectional view of a retractable writing instrument 1 (hereinafter simply referred to as a writing instrument) according to the present invention, and FIG. 2 is a front view thereof. The writing instrument 1 according to the present embodiment includes a front opening 10, a front shaft cylinder 11, a rear shaft cylinder 12, and a rear cap 13 that are assembled in order from the front end (writing section side) to form one writing instrument. A plurality of interior refills 20 and 30 are selectively projected and projected from the tip of 10.
A clip 14 is attached to the rear barrel 12.

  In this embodiment, a mechanical pencil refill 20 and a ballpoint pen refill 30 are provided as refills. The ballpoint pen refill 30 can be provided with two or three different color refills. However, the configuration in which about 1 to 5 refills are installed in the shaft cylinder is known, and a known technique is appropriately used. In the present embodiment, the description will be made assuming that the two refills 20 and 30 are provided.

In the mechanical pencil refill 20, a mechanical pencil core 22 is fed out by a feeding mechanism 23 from a core insertion tube 21 which is a writing tip.
The feeding mechanism 23 biases the chuck (not shown) provided at the front end of the lead tank 24, a chuck ring (not shown) that slides in the axial direction on the outer periphery of the chuck, and the chuck and the lead tank 24 backward. A spring (not shown) or the like is provided.
Then, by pushing the rear cap 13 forward, as the rear shaft cylinder 12 slides with respect to the front shaft cylinder, the chuck is advanced and retracted, and the core 22 is fed forward.

The ballpoint pen refill 30 holds the transfer ball 32 rotatably at the tip of the tip 31 which is the writing tip, and the oil-based oil filled in the ink containing tube 33 by rotating the transfer ball 32 on the paper. Alternatively, aqueous ink is transferred to paper.
In the present application, the configuration of each refill is not limited to the above, and any known technique may be used arbitrarily, and other refills such as a marker refill may be provided.

The rear end of the mechanical pencil refill 20 is provided with a mechanical pencil slide piece 25 which becomes an engaging portion when the refill is projected and retracted. Similarly, the rear end of the ballpoint pen refill 30 is provided with a ballpoint pen slide piece 34. Yes.
Then, by rotating the rear shaft cylinder 12 with respect to the front shaft cylinder 11, the internal rotary cam 15 engages with the mechanical pencil slide piece 25 and the ballpoint pen slide piece 34 and protrudes forward respectively. , Configured to immerse backwards.

Such a rotary pay-out type writing instrument is also known, and for example, a configuration such as Patent Document 5 has been proposed by the present applicant.
In addition, by sliding a pusher provided at the rear part of the writing instrument as in Patent Document 2 back and forth, one of the plurality of refills is selected and made to appear, and the lead-out operation of the refill for the mechanical pencil is performed at the rear end of the shaft cylinder. The present invention can also be applied to a configuration that can be easily performed by the knocking operation. Even if the refill is a single in / out type writing instrument, it can be similarly applied.

JP 2001-71679 A

The present embodiment is a retractable writing instrument having the outline as described above, and has a configuration in which the tip 10 is attached to the front shaft cylinder 11. It should be noted that the front shaft cylinder 11 and the rear shaft cylinder 12 may be configured as a single cylinder instead of being separated.
FIG. 3 shows an enlarged view of the vicinity of the tip 10.
In the present invention, the tip 10 is substantially conical located in the vicinity of the front end of the retractable writing instrument, and a hole 10a is formed at the tip, which is the apex, for the writing tip to protrude. The diameter of the hole portion 10a is slightly larger than the diameter of the writing tip portion, and can be smoothly projected and retracted, and the writing tip portion is supported by the hole portion 10a at the time of writing so that writing is easy.

A screw groove is formed on the outer periphery 10c of the rear end portion of the front opening 10, and a screw groove is also formed on the inner periphery of the attachment portion 11a of the front shaft cylinder 11. Is attached.
The mounting mode is not limited to the case of screwing, and it may be a configuration in which the front end is simply fitted into the shaft tube, or either the concave portion or the convex portion is provided on the front end or the shaft tube. Alternatively, the concave and convex portions may be fitted.
Further, an adhesive may be applied and bonded in the attached state.

In this embodiment, the tip 10 is made of metal, and is formed of, for example, brass, stainless steel, or aluminum. The processing method of the tip 10 is arbitrary, such as press processing and lathe processing, but regular cutting is formed on the surface by cutting with a lathe.
And when the front end and the shaft tube are configured separately as in the present invention, the manufacturing process is such that after placing the refills 20 and 30 in the front shaft tube 11, the front end 10 is screwed together. It will be the order to complete.

  Conventionally, since only the above-described configuration has been used, the writing tip is brought into contact with the inner peripheral surface 10d of the tip 10 when the refills 20 and 30 appear and disappear, and the metal core insertion tube 21 and the tip 31 are in contact with each other. Rubbed and produced an unpleasant contact sound. In particular, in the composite writing instrument as in the present embodiment, the writing tip of the refill 20/30 is moved along the inclined side of the tip 10 at the time of appearance, and the entire refill 20/30 is bent at that time, so that the writing tool axis is bent. Since it protrudes from the hole 10a located in the area, a contact sound is always generated every time it appears and disappears.

Further, frequent friction also causes malfunction such as bending of the core 22 and damage of the core insertion tube 21 in the mechanical pencil and damage of the tip 31 and dropout of the transfer ball 32 in the ballpoint pen.
When the grind is generated as described above, the grind is composed of a large number of irregularities in the circumferential direction, so that friction with the refills 20 and 30 at the time of intrusion is remarkably increased, and the writing tip may be caught. .

  Therefore, the present invention is characterized in that the resin coating 50 is disposed on substantially the entire inner peripheral surface 10d of the tip 10. The resin coating 50 is a thin, substantially conical body made of resin, and is in close contact with the inner peripheral surface 10 d of the tip 10. A hole portion 50a is formed at the apex of the substantially conical body so that the writing tip portion appears and disappears in the same manner as the tip 10.

4 is a partially enlarged view of the portion indicated by A and B in FIG. 3, and FIG. 4A is a partially enlarged view of the A portion in which the mechanical pencil refill 20 is omitted.
The diameter of the hole 50a is preferably the same as that of the hole 10a of the tip 10 as shown in the figure, and the hole inner surface 50b substantially parallel to the axial direction of the hole 50a and the inner peripheral surface of the hole 10a. Surface position is continuous. As a result, there is no unevenness in the tip 10, and the writing tip can appear smoothly.

  Moreover, as another embodiment, the diameter of the hole 50a of the resin coating 50 is configured to be smaller than the diameter of the hole 10a of the tip 10, and before the writing tip portion contacts the tip 10, It may be supported by the elasticity of the resin. In this case, since the resin cover 50 cushions the collision between the side surface of the writing tip and the hole 10a at the time of writing, generation of unpleasant contact noise, impact transmitted to the hand, and the like can be reduced.

And in this invention, while the front-end | tip of the resin coating body 50 makes the engaging surface 50c which is a surface substantially perpendicular | vertical to an axial direction, the front-end | tip of the front port 10 is also a latching part which is a surface refracted in the axial direction. 10b is formed.
The engagement surface 50c is in contact with the locking portion 10b, and the resin cover 50 is not exposed from the hole portion 10a due to the engagement between the two.

In the conventional configuration (for example, Patent Document 3), the resin inside is not locked at the tip of the writing instrument as described above, and may be exposed from the hole portion while repeatedly colliding with the pen tip. There were problems with interference with the pen tip and the appearance.
As described above, the present invention is configured such that the two engage with each other, so that such a problem can be solved.

In addition, in this invention, if the resin coating body and a front end engage, it can implement not only the said structure, For example, the protrusion 10b is provided in the inside other than making the latching | locking part 10b refract the surface of the front end 10. You may make it latch the front-end | tip part vicinity of the resin coating body 50. FIG.
Further, a concave portion or a convex portion may be provided in the vicinity of the front end portion of the resin coating, and a convex portion or a concave portion corresponding to the concave portion or the convex portion may be provided in the vicinity of the tip end portion of the tip so as to engage with each other.

The resin cover 50 may be configured to be fitted in the tip 10 by being formed separately by injection molding, or may be formed integrally with the tip 10 by insert molding.
In the former case, the friction between the resin cover 50 and the inner peripheral surface of the front opening 10 is increased due to the presence of a grind in the front opening 10, and once fitted, it does not easily fall off.
In the latter method, the resin cover 50 is not fitted and integrated with the tip 10 so that it does not fall off.

In any method, the resin coated body 50 is disposed on the inner periphery of the tip 10 so that the writing tips of the refills 20 and 30 operate along the inner peripheral surface 50d of the resin coated body 50. Therefore, it is possible to smoothly move in and out.
As described above, the present invention is a technique that can effectively prevent generation of unpleasant sound at the time of appearance, vibration due to friction, damage to the writing tip, and the like.

Further, the present invention is characterized in that the resin coating 50 is extended to a portion near the front end of the front shaft cylinder 11.
That is, as shown in FIG. 3, the extending portion 50 e of the resin cover 50 is formed from the rear end of the inner periphery of the front opening 10 to the vicinity of the front end of the inner peripheral surface of the front shaft cylinder 11. Here, the front end of the inner peripheral surface of the shaft cylinder according to the present invention is advanced backward from the front opening 10 along the inner periphery except for a portion where the inner peripheral surface is not exposed, such as the front end mounting portion 11a. Indicates the front end position where the inner periphery of the shaft cylinder is exposed.

In the present embodiment, the extending portion 50e is refracted in the writing tool centrifugal direction along the rear end cross section of the front opening 10 in the vicinity of the front end of the front shaft cylinder 11, and comes into contact with the inner peripheral surface of the front shaft cylinder 11. Is formed.
By having such a shape, the resin cover 50 is completely adhered to the inner peripheral surface of the front opening 10, and the refracted portion is locked to the rear end cross section of the front opening 10, so that it does not shift forward. . In addition, the inner peripheral surface of the front shaft cylinder 11 is also reliably contacted.
Further, since the extending portion 50e covers the rear end cross section of the front opening 10, when the front opening 10 is removed when the refill is replaced, the metal portion of the rear end cross section of the front opening 10 is exposed and exposed. There is no direct collision with the part cylinder 11. Thereby, generation | occurrence | production of a damage | wound and unusual sound can be prevented.

  In the present invention, the front shaft tube 11 is securely attached to the front shaft tube 11 by the contact between the front shaft tube 11 and the contact surface 50f of the extending portion 50e. The resin cover 50 has elasticity, and is difficult to slip between the inner peripheral surface of the front shaft cylinder 11 due to friction of the resin surface, and the front shaft cylinder 11 rotates or slides in the front-rear direction with respect to the front opening 10. It becomes difficult.

  In particular, when the front opening 10 and the front shaft cylinder 11 are screwed together as in the present embodiment, there has conventionally been a drawback that the screw is liable to loosen and the user has to retighten each time. According to the above configuration, the looseness is greatly reduced by the friction of the contact surface 50f of the resin coating.

The shape of the extending portion 50e of the resin coating 50 is preferably refracted toward the inner peripheral surface of the front shaft cylinder 11 as described above. However, depending on the flexibility of the resin even if it is simply extended backward. It can contact with the front shaft cylinder 11 to cause friction.
The stretched length of the stretched part 50e can be determined as appropriate, but is suitably 0.2 mm to 5 mm, more preferably 0.5 mm to 1.5 mm. By making this length, it does not become an obstacle when the front opening 10 is attached to the front shaft cylinder 11, and both the attachments act so as not to loosen by contacting the inner peripheral surface of the front shaft cylinder 11. .

In order to further increase the friction on the contact surface 50f, a convex portion that comes into contact with the inner peripheral surface of the front shaft cylinder 11 can be provided on the surface of the contact surface 50f. This structure will be described with reference to FIGS.
FIG. 5A is a cross section of the writing instrument 1 at the position of the extending portion 50e, and the internal mechanism is omitted. In FIG. 4B and FIG. 5, the rib part 50g which is a micro convex part is formed along the outer periphery periphery of the extending | stretching part 50e. The rib portion is an annular rib, and the outer periphery thereof linearly contacts the inner peripheral surface of the front shaft cylinder 11. In FIG. 4B, the front shaft cylinder 11 is omitted. When actually contacting the front shaft cylinder 11, the rib portion 50g is slightly compressed and deformed.
By providing such a convex portion, the contact pressure is concentrated, and sliding between the inner peripheral surface of the front shaft cylinder 11 can be effectively suppressed.

Further, as shown in FIG. 5B, a plurality of minute convex portions 50h may be provided on the outer peripheral surface of the extending portion 50e. It is preferable to provide a plurality of minute protrusions 50h on the circumference, and in particular, for example, two, four (shown), six, or eight can be provided at positions opposed in the diameter direction.
The upper end of the minute projection 50h contacts the inner peripheral surface of the front shaft cylinder 11 in a dot shape. Also with this configuration, it is possible to effectively suppress sliding between the inner peripheral surface of the front shaft cylinder 11.

Furthermore, in the formation of such a minute convex portion, the use of a gate mark (so-called burr) used at the time of injection molding of the resin coating 50 is extremely simple and preferable.
That is, in the molding of the resin coating 50, two gates are respectively opened toward the shaft center at positions symmetrical with respect to the shaft center on the inner surface of the cavity, and the synthetic resin melted from both gates is simultaneously high-speed and high-pressure. By filling with, the inflowing resin wraps around and joins and spreads over the entire axial direction to complete the molding.

As a result of the above molding, two gate traces remain at the gate position. Although such a gate trace is originally cut and removed, it is proposed in the present invention that the gate is disposed on the contact surface 50f to form a convex portion by the gate trace.
According to this configuration, not only can the gate trace formed in the molding process of the resin coating 50 be used as it is to form the convex portion, but also the gate trace processing becomes unnecessary, which contributes to simplification of the process.

Although any synthetic resin and natural resin can be used as the material of the resin coating 50, PP resin is used in this embodiment. PP resin has excellent moldability and is easy to process.
In the configuration in which the mechanical pencil refill appears and disappears as in the present embodiment, when the mechanical pencil core 22 protrudes from the tip, it contacts the resin coating 50. At this time, if a material having low hardness is used for the resin cover 50, the core 22 may be stuck or caught in the resin cover 50.
Therefore, in this embodiment, a PP resin having a relatively high hardness is used to prevent the core from being damaged and to obtain good usability.
A synthetic resin such as POM, PE, and ABS can be selected as appropriate in consideration of the working distance of the refill and the operating condition.

In the case of a structure that does not use a mechanical pencil refill or a refill that has a structure in which the core protrudes and does not appear and disappear, the above-described problems are unlikely to occur, and therefore a thermoplastic elastomer resin having low hardness can be used.
It is preferable that the resin cover 50 has sufficient flexibility to be able to adhere to the front end 10 at the same time that sufficient shock absorption at the time of contact with the refill can be secured.

The present invention is not limited to the prevention of unpleasant contact noise and damage by the resin coating 50, but the friction between the refills 20, 30 and the friction between the refills 20, 30 and the inner peripheral surface of the front shaft cylinder 11. It is also intended to prevent sound and damage caused by the noise. FIG. 6 shows a configuration for realizing this.
6A is an enlarged cross-sectional view of the mechanical pencil refill 20 behind the feeding mechanism 23, and FIG. 6B is an enlarged view thereof.

  In the present invention, an annular recess 26 is formed in the outer periphery of the mechanical pencil refill 20, and a rubber O-ring 60 is attached to the recess 26. Since the inner diameter of the O-ring 60 is smaller than the outer diameter of the mechanical pencil refill 20, the O-ring 60 is moved and fitted to the recess 26 in an expanded state, and after fitting, the O-ring 60 contracts and thus does not move back and forth.

The formation position of the concave portion 26 is a portion that contacts the front end position of the tip 31 of the ballpoint pen refill 30 in a state in which the mechanical pencil refill 20 protrudes, and the O-ring 60 abuts on the tip 31, whereby the refill 20. 30 is prevented from contacting directly.
Since the position is closest to the hole 10a of the tip 10 and hits the front end of the tip 31, the distance between the refills 20 and 30 is the shortest. By attaching the O-ring 60 to this part, the contact sound can be most effectively prevented.

Further, when the mechanical pencil refill 20 is immersed, the core insertion tube 21 is not supported by the tip 10 and thus is easily vibrated in the front shaft tube 11. Conventionally, the chuck 20 is gripped by a collision with the front shaft tube. In some cases, the core 22 is broken or the core insertion tube 21 is damaged.
By mounting the O-ring 60 as described above, the O-ring 60 cushions against the inner peripheral surface of the front shaft cylinder 11, which contributes to the prevention of these problems and collision noise.

The O-ring 60 is preferably attached to the mechanical pencil refill 20 where core breakage or the like is likely to occur. By attaching the O-ring 60 to the refill 20, the O-ring 60 contributes to shock reduction of other refills 30.
However, it may be provided in other refills, and can be attached to all refills.

The plane sectional view of the retractable writing instrument concerning the present invention. Same as above, front view. The enlarged view of the tip vicinity of the retractable writing instrument which concerns on this invention. The partial enlarged view of the front-end | tip part and the rear-end part vicinity similarly. Explanatory drawing of the structure which provided the convex part in the resin coating body 50 which concerns on this invention. Explanatory drawing of the structure which provided the O-ring which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Writing implement 10 Front opening 10a Hole part 10b Locking part 10c Rear end part 10d Inner peripheral surface 11 Front axial cylinder 11a Front opening attachment part 20 Mechanical pencil refill 21 Core insertion tube 22 Core 23 Feeding mechanism 30 Ballpoint pen refill 31 Tip 32 Transfer Ball 33 Ink Storage Tube 50 Resin Cover 50a Hole 50b Hole Inner Surface 50c Engagement Surface 50d Inner Peripheral Surface 50e Extension Portion 50f Contact Surface

Claims (5)

In the retractable writing instrument provided with one or a plurality of refills in the shaft cylinder, the writing tip of the refill can be projected and retracted from the front end attached to the front end of the shaft cylinder,
A retractable writing instrument comprising a resin coating for covering the inner peripheral surface of the tip, and extending the resin coating to at least a portion near the front end of the inner peripheral surface of the shaft cylinder. The retractable writing instrument according to claim 1, wherein a locking portion that locks at least an axial displacement of the resin coating is formed in the front opening. 3. The retractable writing instrument according to claim 1, wherein a convex portion that comes into contact with the inner peripheral surface of the shaft cylinder is provided in the vicinity of the front end of the inner peripheral surface of the shaft cylinder of the resin coating. The retractable writing instrument according to claim 3, wherein the convex portion is formed by a gate mark used when molding the resin coating. The retractable writing instrument according to any one of claims 1 to 4, wherein an elastic annular body having elasticity is disposed on an outer periphery of the refill.

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