JP2013215935A - Duplex writing utensil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that a mechanical pencil mechanism bites (breaks) a lead by the shock when the mechanism is accommodated in a shaft.SOLUTION: In a writing utensil, a mechanical pencil unit having a chuck body for holding and releasing a lead and a chuck ring which surrounds a front portion of the chuck body and opens/closes the chuck body is arranged retractable in a shaft cylinder. An outer circumferential part corresponding to a lead holding part of the chuck body includes at least a horizontal portion substantially parallel to the axis and an inclined portion which is located behind the horizontal part and inclined in the axial direction. On the other hand, an inner circumferential part of the chuck ring is formed substantially parallel to the axis. In the writing utensil in which the mechanical pencil unit is retractable, the ratio K/D is ≥14% and <30%, where K denotes the sliding area in which the chuck ring is slidable to the chuck body when the chuck body is attached to the chuck ring to hold the lead, and D denotes the length from a front end of the chuck body to a rear end of the inclined surface.

Description

  The present invention relates to a writing instrument in which a mechanical pencil unit such as a double knock type mechanical pencil or a double-type writing instrument in which a plurality of writing bodies including at least a mechanical pencil unit are arranged in a shaft body so as to move back and forth is arranged to be able to appear and retract.

As an example, a mechanical pencil unit is provided in front of a slider guided in the axial direction in each of slits (longitudinal slit portions) having a front shaft detachably fixed to the front of the middle shaft and drilled at a plurality of positions on a side surface of the middle shaft. Or there is a double writing instrument with a ballpoint refill fixed.
More specifically, the mechanical pencil unit has a core pipe and a mechanical pencil writing body, the core pipe is fixed in front of the slider, and the mechanical pencil writing body is attached in front of the core pipe. Here, the mechanical pencil unit connects the core pipe and the mechanical pencil cursive with a joint, but this joint has a large diameter part and a small diameter part formed in front of the large diameter part, A chuck spring is stretched around the small diameter portion. The mechanical pencil writing body incorporates a general chuck mechanism, and is joined to the core pipe through a joint connected to the chuck mechanism at the rear end, and the rear end of the core pipe is fitted into the hole of the slider. The lead is fed out by interlocking the chuck with the back and forth movement of the slider in a state where the step portion of the base of the mechanical pencil writing body is in contact with the inner step portion of the front shaft. The ballpoint pen refill has a receiving pipe, a lead holder, and a ballpoint pen writing body. The receiving pipe is fixed to the front of the slider, and the lead holder is attached to the front of the receiving pipe. The tip of the ballpoint pen is held in a protruding state. Each slider is provided so that it can be moved back and forth by urging a return spring between the front of the slider and the front end of the center shaft, and either one of the end portions of each writing body is provided with a projecting hole (front end opening) of the front shaft. ) And the other cursives at the forward position are retracted, the front end of each cursive object is made to come into contact with the slider and the central shaft when the cursive retreats (return). Is housed.

    JP 2006-142522 A.

However, since the above-mentioned conventional technology generates a strong impact in the front-rear direction when the slider and the center shaft collide with each other, when the writing body is a mechanical pencil, the mechanical pencil core accommodated in the chuck mechanism is eaten by the impact force. There was a problem of tearing (breaking). In other words, when the mechanical pencil in the protruding state is released, the mechanical pencil is retracted by the urging force of the return spring, and the rear end of the slider of the mechanical pencil collides with the center shaft (shock). And produces a strong impact. Here, since the slider and the central shaft are not elastic members, the impact is not absorbed. Also, since the mechanical pencil cursive (the slider) stops suddenly, the impact is transmitted to the mechanical pencil unit in the direction of the tip of the mechanical pencil cursive. Due to the sudden stop, a force is applied to the chuck spring in the mechanical pencil unit once in the direction of compression (backward), but it immediately reverses and a force in the extension direction (forward) acts. As a result, the chuck ring moves in a direction to enclose the chuck body, and at this time, there is a problem that the core is bitten (broken).
The double knock mechanical pencil has the same problem due to the impact when the mechanical pencil mechanism is housed in the shaft.

  Therefore, the present invention has a mechanical pencil unit having a chuck body for gripping and opening the core and a chuck ring for surrounding the front of the chuck body and for opening and closing the chuck body so as to be able to appear and retract in the shaft cylinder. It is a writing instrument, and an outer peripheral portion corresponding to the core gripping portion of the chuck body is formed from at least a horizontal portion substantially parallel to the axis and an inclined portion that is located behind the horizontal portion and is inclined in the axial direction. On the other hand, the inner periphery of the chuck ring is formed substantially parallel to the axis, the chuck body is fitted to the chuck ring, and the chuck ring slides on the chuck body when gripping the core. The gist is that the ratio K / D is 14% or more and less than 30%, where K is the region and D is the length from the front end of the chuck body to the rear end of the inclined surface.

  The present invention is a writing instrument in which a mechanical pencil unit having a chuck body for gripping and releasing a lead and a chuck ring for opening and closing the chuck body and surrounding the front of the chuck body is arranged to be able to appear and retract in a shaft cylinder. And forming an outer peripheral portion corresponding to the core gripping portion of the chuck body at least from a horizontal portion substantially parallel to the axis, and an inclined portion that is located behind the horizontal portion and is inclined in the axial direction, On the other hand, the inner peripheral portion of the chuck ring is formed substantially parallel to the axis, the chuck body is fitted to the chuck ring, and a sliding region where the chuck ring slides with the chuck body when gripping the core is formed. K, when the length from the front end of the chuck body to the rear end of the inclined surface is D, the ratio K / D is 14% or more and less than 30%. Due to an impact force transmitted to the chuck ring and the chuck body when releasing the pencil unit in Yapupenshiru, eating core tear (fracture) can be prevented.

The external appearance front view which shows this invention. The side view of FIG. The longitudinal cross-sectional view of FIG. Front enlarged view of FIG. The WW sectional view taken on the line of FIG. The V section expansion of FIG. The YY sectional view taken on the line of FIG. The single-piece | unit perspective view of the slider for ball-point pen refills. The exploded view of the essential parts of the ballpoint pen refill, connecting member and slider. The perspective view of a single unit of a ballpoint pen refill slider (modification). The disassembled principal part enlarged view of a ball-point pen refill, a connection member, and a slider (modification example). The external appearance perspective view which shows the connection state in FIG. The front view of the slider for ball-point pen refills. The external appearance perspective view of a connection member. The front view of a connection member. The side view of FIG. AA line sectional view of Drawing 12. BB sectional drawing of FIG. The external appearance perspective view of the slider for a mechanical pencil unit. The longitudinal cross-sectional view of a mechanical pencil unit. The side view which shows the connection state of the lead tank of a mechanical pencil unit, and a slider. FIG. 22 is a longitudinal sectional view of a mechanical pencil unit slider and a lead tank connecting portion in FIG. 21. (A) The external appearance perspective view which shows the connection state of a mechanical pencil unit and a slider. (B) The side view which shows the connection state of a mechanical pencil unit and a slider. A modification of the slider connection for the mechanical pencil unit. The side external view which assembled | attached the slider of FIG. 24 to the mechanical pencil unit. (A) The external appearance perspective view which shows operation | movement (slider retreat position). (B) The external appearance perspective view which shows operation | movement (slider advance position). The longitudinal cross-sectional view of FIG.26 (b). The longitudinal cross-sectional view in the state where a mechanical pencil unit protrudes. FIG. 29 is a front longitudinal sectional view of FIG. 28. FIG. 30 is an enlarged view around the chuck body of FIG. 29. The front view (front direction) of this writing instrument in the state of FIG.26 (b). CC direction cross-section arrow directional view of FIG. From the state of FIG. 29, the state when the lead is fully extended.

  The operation will be described. The present invention is a writing instrument in which a mechanical pencil unit having a chuck body for gripping and releasing a lead and a chuck ring for opening and closing the chuck body and surrounding the front of the chuck body is arranged to be able to appear and retract in a shaft cylinder. And forming an outer peripheral portion corresponding to the core gripping portion of the chuck body at least from a horizontal portion substantially parallel to the axis, and an inclined portion that is located behind the horizontal portion and is inclined in the axial direction, On the other hand, the inner peripheral portion of the chuck ring is formed substantially parallel to the axis, the chuck body is fitted to the chuck ring, and a sliding region where the chuck ring slides with the chuck body when gripping the core is formed. K, where D is the length from the front end of the chuck body to the rear end of the inclined surface, the ratio K / D is 14% or more and less than 30%. Even if the deviation is Sawaten S, not take excessive lead gripping force to the core. Therefore, the core is not damaged, the core biting (core breakage) can be prevented, and the composite writing instrument can be easily used.

A first embodiment of the present invention will be described with reference to FIGS. In the figure, the lower part is called the front and the upper part is called the rear. An example is a multi-core writing instrument (double writing instrument) in which a ballpoint pen refill composed of two colors, black and red, and a mechanical pencil unit are slidably arranged. The writing body arranged in the shaft main body (shaft cylinder) of the dual writing instrument is a writing body including at least a mechanical pencil unit, and is not limited to a ballpoint pen refill, for example, a stylus pen or a stick-shaped eraser feeding body (refill). Etc.
Reference numeral 1 denotes a shaft main body (shaft cylinder), and the shaft main body 1 includes a front shaft 2 and a rear shaft 3. Further, in this example, the front shaft 2 is configured by a screwed structure of the tip member 4 and the middle shaft 5, but may be press-fitted by uneven fitting or may be integrally formed. However, considering the ease of exchanging the cursive and the molding described later, it is better to use two members and fix them detachably. In addition, a conical portion 4a whose diameter gradually decreases toward the distal end side is formed in the inner diameter portion of the tip member 4. A protruding hole 4b in which the cursive body appears and disappears is formed at the tip of the tip member 4. In addition, since a plurality of flat portions 4c that are long in the longitudinal direction of the shaft body 1 are formed in the inner diameter portion of the tip member 4, when the shaft body 1 (the tip member 4) is transparent, the flat portion 4c. By the lens effect obtained by the above, it is possible to easily identify the color of the mechanical pencil unit and the ballpoint pen refill disposed inside, and a high-quality feeling can be obtained (see FIGS. 1 to 4 and FIG. 29). In this embodiment, the shaft body 1 is made of a transparent or colored translucent material. However, the present invention is not limited to this, and the shaft body may be made of a colored and opaque material.

The rear shaft 3 is formed with three slits 6 in the longitudinal direction (see FIG. 5). In this example, three slits 6 are formed, because the number of ballpoint pen refills that are cursive letters is two and the number of mechanical pencil units is one, depending on the number of cursive letters. The number of slits formed also varies. Further, the slit 6 is formed up to one end portion of the rear shaft 3, and sliding grooves 7 are formed substantially in a straight line on both sides of the slit 6. The rear shaft 3 is formed with a slide surface 3a having substantially the same length as the slide groove 7 in the longitudinal direction. However, the sliding groove 7 and the sliding surface 3a are not formed over the entire length of both sides of the slit 6, but are formed only up to the middle portion. The slide surface 3a receives the back surface of a slide projection 12 described later. Further, a narrow slit portion 6a having a narrower width than the sliding groove 7 of the slit 6 is formed (see FIG. 6).
In front of the rear shaft 3, leg portions 8 having a semicircular shape with a cross-sectional shape having an arcuate portion on the outside are formed at intervals of 120 degrees. The leg portion 8 is formed by forming the slit 6. Therefore, the number of legs 8 varies depending on the number of cursive letters. The circumscribed circle diameter of the leg portion 8 is formed smaller than the maximum outer diameter of the rear shaft 3 (see FIG. 7).
Reference numeral 9 denotes a clip portion formed integrally with the rear shaft 3, but it may be formed of a separate member and fixed to the rear shaft 3. Reference numeral 10 denotes a ball portion formed on the front inner surface of the clip portion 9, and the ball portion 10 is in contact with the surface of the middle shaft 5.

A slider 11 made of a transparent or colored translucent material is slidably disposed in the slit 6 of the rear shaft 3. The slider 11 includes a slider 11B for ballpoint pen refill and a slider 11S for a mechanical pencil unit. Here, the slider 11B for ballpoint pen refill will be described in detail. Sliding projections 12 are formed on both sides of the slider 11B in the longitudinal direction, and are slidably engaged with sliding grooves 7 formed in the slit 6 (see FIGS. 5 and 6). . The engagement relationship between the sliding protrusion 12 and the sliding groove 7 is the same for both the ballpoint pen refill slider 11B and the mechanical pencil unit slider 11S. Two release projections 13 and 14 are formed on the back surface of the slider 11B with an extension 111 therebetween. In the present embodiment, the side surface of the slider 11B does not have a hole 11Sf like a mechanical pencil slider 11S described later (see FIGS. 8 and 9).
However, the present invention is not limited to this, and as a modification, three holes 11Sf may be provided on the side surface of the slider 11B (see FIGS. 10 and 11). When the holes 11Sf are provided, the three holes 11Sf provided on the side surface of the slider 11B are constituted by through holes and non-through holes. Specifically, the hole 11Sf formed in the vicinity of the release protrusion 13 and the hole 11Sf formed in the vicinity of the release protrusion 14 are through-holes penetrating the extension portion 111, A hole 11Sf formed in the front portion of the slider 11B is a non-through hole (see FIG. 10). And although the hole 11Sf which is the said through-hole is located in the narrow slit part 6a, the half of the hole 11Sf is exposed from the narrow slit part 6a. By exposing about half of the hole 11Sf from the narrow slit 6a, dust and dust stored in the hole 11Sf can be efficiently discharged from both openings of the hole 11Sf. On the other hand, a part of the hole 11 </ b> Sf that is a non-through hole is located in the sliding protrusion 12. That is, a part of the sliding protrusion 12 is notched by the hole 11Sf. As a result, elasticity is generated in the front portion of the sliding projection 12, and a smooth sliding operation can be obtained even if some dimensional variation occurs.
In addition, a fine protrusion is formed on the circumference substantially at the center of the inner peripheral surface of the through hole 11Sf. By forming protrusions on the inner peripheral surface on the circumference, when the slider is a resin molded product, the moldability can be improved as described later.
In this example, the vertical cross-sectional shape of the hole 11Sf is circular, but may be an ellipse, a triangle, a square, a polygon, or a combination thereof, but when the slider 11S is a molded product, Considering its formability, the round shape is good. The number of holes 11Sf is three in this example, but may be one, four, five, or the like.

Then, one end portion (rear portion 15a) of the connecting member 15 having a color substantially the same as the color of the ink stored in the later-described cursive body is detachably inserted into the hole 11a of the slider 11B. A cylindrical ball-point refill 16B made of a resin material such as polypropylene or nylon is connected to the other end portion (front portion 15b) of the connecting member 15 (see FIG. 9).
The ballpoint pen refill 16B includes an ink storage tube (pipe portion) 16Ba formed by extrusion molding of a resin material such as polypropylene that stores ink, and a ballpoint pen tip (writing portion) press-fitted in front of the ink storage tube 16Ba. ) 16Bb and the like (see FIG. 12). Since it is press-fitted into the ink storage tube 16Ba, the outer diameter of the ballpoint pen tip 16Bb is smaller than the outer diameter of the ink storage tube 16Ba. For this reason, a step portion is formed at the front end portion of the ink storage tube 16Ba. Here, the front end portion of the ink storage tube 16Ba is 16Bf.
Here, since the slider 11B is formed of a transparent or colored translucent material, the color and display of the connection member 15 located inside the slider 11B can be easily identified. In addition, since the slider 11B has a flat surface portion 11b and a curved surface portion 11c, the color of the connecting member 15 can be more easily identified by the lens effect obtained thereby (FIG. 13).
The slider 11B is not limited to a transparent or colored translucent material, and may be formed from a colored opaque material. In the case of a colored opaque member, the color of the ball-point pen refill 16B can be visually identified by attaching the ball-point refill 16B containing ink of substantially the same color as the colored color. In this embodiment, the connecting member 15 is interposed between the ballpoint pen refill 16B and the slider 11B. However, the connecting member 15 may be formed integrally with the slider 11B. Also in this case, the color of the ball-point pen refill 16B can be visually identified by attaching the ball-point refill 16B to the slider 11B having substantially the same color as the color of the built-in ink.

  A large-diameter portion 15c is formed in the intermediate portion of the connecting member 15, and excessive insertion of the rear portion 15a into the hole 11a and excessive insertion of the front portion 15b into the writing body 16B are prevented. In addition, a circumferential fitting protrusion 15d is formed on the rear portion 15a of the connecting member 15 in order to improve the insertion and fitting of the slider 11B into the hole 11a, while the front portion 15b A flat surface portion 15e is formed for air to enter the ballpoint pen refill 16B. The flat portion 15e is formed in four directions with an angle of 90 degrees. That is, the cross-sectional shape of the front portion 15b of the connection member 15 is a square shape. The four flat portions 15e are partially formed with protrusions 15f and 15g in order to obtain a good engagement / fitting force with the ballpoint pen refill 16B, but the protrusions do not overlap each other. . That is, each protrusion 15f formed on the four flat portions 15e is formed at a different position with respect to the longitudinal direction and the circumferential direction (see FIG. 14). More specifically, a protrusion 15g is formed opposite to the protrusion 15f formed at the front facing position and at an angle of 90 degrees with the protrusion 15f at the rear (see FIGS. 15 and 16). reference). The air penetrating the inside of the ballpoint pen refill 16B due to the consumption of the ink is ensured, and the drop-off from the connecting member 15 due to plastic deformation of the ink containing tube 16Ba made of a resin material is prevented. That is, the ball-point pen refill 16B swells in an elliptical shape by the protrusion 15f formed at the front, and the bulge 16Bd is formed at an angle of 90 degrees with respect to the bulge by the protrusion 15g formed at the rear. It is formed. That is, while the bulging direction and the 90-degree rotated direction are reduced in diameter, the inner surface of the ink storage tube 16Ba bites into the protrusions 15f and 15g. As the engaging portion becomes stronger, the relative rotation between the connecting member 15 and the ink containing tube 16Ba is prevented (see FIGS. 17 and 18; the dotted line 16Be in the figure indicates the inner surface of the original ballpoint pen refill 16B). Shape.)

The protrusions 15f and 15g have an arrow shape in cross section, but the insertion side of the protrusion 15f located on the front side to the ballpoint pen refill 16 is formed at an obtuse angle (α). The separation side is formed at an acute angle (β). Incidentally, in this example, the insertion side is formed at about 150 degrees and the separation side is formed at 70 degrees (see FIG. 16).
An extension portion 11d that holds an outer diameter portion of an elastic member 17B, which will be described later, is formed at the front end portion of the slider 11B (see FIG. 8). The length between the extended portions 11d is formed to be slightly shorter than the outer diameter of a later-described elastic member 17B, whereby the elastic member 17B is press-fitted into the extended portion 11d. That is, even when the ballpoint pen refill 16B is replaced, the elastic member 17B is prevented from being detached from the front end portion of the slider 11B. Further, the insertion force (fitting force) of the slider 11B to the connection member 15 (rear part 15a) is set to be weaker than the insertion force (fitting force) of the ball pen refill 16B to the connection member 15 (front part 15b). That is, when the ball-point refill 16B is to be separated from the slider 11B, the ball-point refill 16B is detached from the slider 11B in a state where the ball-point refill 16B and the connection member 15 are coupled. Reference numeral 17B denotes a ball-point refill 16B and a resilient member such as a coil spring that urges the slider 11B connected to the ball-point refill 16B backward (see FIG. 3). The elastic member 17B has a higher spring constant than the elastic member 17S such as a coil spring that urges the slider 11S connected to the mechanical pencil unit 16S and the core tank 161 to be described later.

  Next, the middle shaft 5 will be specifically described. A restricting portion 18 is formed in an intermediate portion of the middle shaft 5 which is one member of the front shaft 2, and three through holes 19 into which the writing bodies 16 </ b> B and 16 </ b> S are loosely inserted are formed in the restricting portion 18. The curling bodies 16B and 16S are urged rearward by locking the ends of the elastic members 17B and 17S to the restricting portion 18. In addition, three grooves 20 are formed in the longitudinal direction inside the middle shaft 5 and behind the restricting portion 18, and the legs 8 of the rear shaft 3 are slidably contacted with the grooves 20. 8 is guided. Further, the groove portion 20 has substantially the same shape as the cross-sectional shape of the leg portion 8. That is, it has a half-moon shape having an arc portion on the outside.

Next, the mechanical pencil slider 11S will be described in detail. Sliding projections 12 are formed on both sides of the slider 11S in the longitudinal direction, and are slidably engaged with sliding grooves 7 formed in the slit 6 (see FIGS. 5 and 6). . Two release projections 13 and 14 are formed on the back surface of the slider 11S with an extension 111 therebetween, as shown in FIG. Further, three holes 11Sf are provided on the side surface of the slider 11S, and these are constituted by through holes and non-through holes. Specifically, the hole 11Sf formed in the vicinity of the release protrusion 13 and the hole 11Sf formed in the vicinity of the release protrusion 14 are through-holes penetrating the extension portion 111, A hole 11Sf formed in the front portion of the slider 11 is a non-through hole. And although the hole 11Sf which is the said through-hole is located in the narrow slit part 6a, the half of the hole 11Sf is exposed from the narrow slit part 6a. By exposing about half of the hole 11Sf from the narrow slit 6a, dust and dust stored in the hole 11Sf can be efficiently discharged from both openings of the hole 11Sf. On the other hand, a part of the hole 11 </ b> Sf that is a non-through hole is located in the sliding protrusion 12. That is, a part of the sliding protrusion 12 is notched by the hole 11Sf. As a result, elasticity is generated in the front portion of the sliding projection 12, and a smooth sliding operation can be obtained even if some dimensional variation occurs. In addition, a fine protrusion is formed on the circumference substantially at the center of the inner peripheral surface of the through hole 11Sf. By forming protrusions on the inner peripheral surface on the circumference, when the slider is a resin molded product, the moldability can be improved as described later.
In this example, the vertical cross-sectional shape of the hole 11Sf is circular, but may be an ellipse, a triangle, a square, a polygon, or a combination thereof, but when the slider 11S is a molded product, Considering its formability, the round shape is good. The number of holes 11Sf is three in this example, but may be one, four, five, or the like.
Further, an arc portion 11Sg, which is a part of the circumference, is formed between the front end surface of the sliding projection 12 and the rear cylinder portion 25 described later in order to hold the inner diameter portion of the elastic member 17S described later. ing. The circular arc part 11Sg is also formed at opposing positions, and there are two places. (See FIG. 19. The arc portion 11Sg at the opposite position is not shown). The radius of the arc portion 11Sg is formed to be slightly larger than the radius of the inner diameter of an elastic member 17S, which will be described later, whereby the elastic member 17S is pressed into the arc portion 11Sg. Reference numeral 17S denotes an elastic member such as a coil spring that urges the slider 11S connected to the mechanical pencil unit 16S and the lead tank 161 backward (see FIG. 3). The elastic member 17S has a lower spring constant than the elastic member 17B such as a coil spring that urges the ball pen refill 16B and the slider 11B connected to the ball pen refill 16B backward.
Further, in this embodiment, the elastic member 17S is made of a coil spring, and both end portions of the elastic member 17S are provided with end winding portions (both end end winding portions), and at the two intermediate positions. Part (intermediate end turn part) is provided (see FIG. 3). In this way, by providing an intermediate end winding portion at least at one location, the effective winding portion other than the end winding portion is divided and shortened to prevent the effective winding portion from bulging and bending in the radial direction. I can do it. Further, it is possible to prevent poor operability due to rubbing between the elastic members and other parts, scratches, and abnormal noise due to rubbing, and to use the mechanical pencil unit satisfactorily. The elastic member having the intermediate winding is useful for the ball pen refill, and the same effect can be obtained. However, in the case of the mechanical pencil unit, the mechanical pencil unit is compared with the case of the ball pen refill. Since the pressing operation for paying out the core is required even after the selection / projection and locking, the elastic member 17S having the intermediate winding portion is more useful.
Further, in the elastic member 17S, the end winding portions (intermediate end winding portions) provided at two intermediate positions may be different from each other so that the number of turns is larger than the end winding portions (both end end winding portions) provided at both ends. good. Increasing the number of windings of the intermediate counterwinding portion over the both end wound portions can prevent the elastic members from being entangled in the single state of the elastic member before assembly. In the case of a mechanical pencil unit, the length of the elastic member is longer than in the case of a ballpoint pen refill because it requires a pressing operation to pay out the lead even after the mechanical pencil unit is selected / projected and locked. Become. Therefore, increasing the number of intermediate end windings is useful for preventing entanglement of the elastic members at the center. In this embodiment, the both end wound portions are 3 turns each, and the intermediate end wound portion is 4 turns each.

A connecting portion 21 for connecting a core tank 161 of a mechanical pencil unit 16S described later is formed in front of the mechanical pencil slider 11S (see FIGS. 19 to 22 and FIG. 28). The connecting portion 21 will be described in detail. The connecting portion 21 includes a pyramid-shaped front cylindrical portion 22 having an inclined surface 22a that gradually changes in diameter from a circular shape to an octagonal shape from the front end toward the rear, and its A groove 23 is formed behind the front cylinder 22 and having a smaller diameter than the outer shape of the front cylinder 22. Here, the shape of the front cylinder portion 22 is an octagon, but the shape is not limited to this, and it is sufficient that the connection with the core tank 161 described later is a point contact. For example, a quadrangular shape, a pentagon shape, a decagon shape, a dodecagon shape, or the like may be used. Further, an inclined surface 24 whose diameter increases toward the rear is formed behind the groove portion 23, and a rear cylinder portion 25 is formed behind the inclined surface 24.
The slider 11S is formed with a substantially hemispherical flange portion 11Sd having a width larger than the width of the slit 6. By widening the flange portion 11Sd, the projecting operation of the mechanical pencil unit 16S is improved and the centering operation can be easily performed. In the centering operation, the slider 11S moves in the axial direction of the rear shaft 3. To avoid being immersed.

The mechanical pencil unit 16S also includes a core tank 161 that contains a plurality of cores and is formed of a metal material, and a chuck that holds and opens the cores that are attached to the front of the core tank 161 via a joint member 162. A body 163, a chuck ring 164 surrounding the front of the chuck body 163 and opening and closing the chuck body 163, a guide cylinder 165 arranged to cover the chuck body 163, and the guide cylinder 165 and the guide cylinder 165 It is arranged between the joint member 162 and an elastic member 166 made of a coil spring or the like that biases the chuck body 163 and the core tank 161 backward. Further, a tip member 167 is detachably attached to the tip of the guide tube 165 by means such as screwing, and the rearward movement of the lead core is restricted inside the tip member 167. A core detent member 168 made of a rubber-like elastic body is provided.
The material of the joint member 162, the guide tube 165, and the tip member 167 of the exterior parts constituting the mechanical pencil unit 16S may be subjected to surface treatment such as plating on a metal such as brass, or a resin molded product such as polyacetal or nylon But it ’s okay.

Next, the chuck body 163 and the chuck ring 164 will be described in detail with reference to FIG.
As shown in FIG. 30, the chuck body 163 has an outer peripheral portion 163b corresponding to the core gripping portion 163a, and the outer peripheral portion 163b includes a horizontal portion 163c and an inclined surface 163d. The horizontal portion 163 c is formed as a peripheral surface substantially parallel to the axis of the chuck body 163 from the vicinity of the front end of the chuck body 163. An inclined surface 163 d that is a peripheral surface inclined toward the axial center of the chuck body 163 is formed from the rear end of the horizontal portion 163 c of the chuck body 163. The inclined surface 163d is formed with a gentle gradient of about 3 to 4 degrees with respect to the axial direction in order to obtain an effective gripping force of the core. Further, a guide inclined surface 163e, which is a peripheral surface inclined toward the axial center of the chuck body 163, is formed also from the rear end of the inclined surface 163d. The guide inclined surface 163e has a larger inclination angle than the inclined surface 163d, making it easier to externally install the chuck ring 164. In this embodiment, the inclination angle of the guide inclined surface 163e is 25 °. The rear end of the guide inclined surface 163e is connected to the body diameter portion 163f of the chuck body 163.
The front end of the core gripping portion 163a of the chuck body 163 is connected to an R portion 163i formed from the front end of the chuck body 163, and this R portion 163j is gripped when the chuck body 163 grips the core. Formed to avoid force concentration. Further, the rear end of the core gripping portion 163a of the chuck body 163 is connected to a tapered portion 163h formed on the rear side. The tapered portion 163h is formed so that the core can be easily inserted into the core gripping portion 163a, and is connected to the through hole 163i through which the core is inserted. In the present embodiment, the rear end of the core gripping portion 163a of the chuck body 163 is located behind the rear end of the guide inclined surface 163e in the outer peripheral portion 163b of the chuck body 163.

  On the other hand, in the chuck ring 164, an inner peripheral portion 164a of the chuck ring 164 to which the inclined surface 163d of the chuck body 163 is fitted is formed in parallel to the axial direction. At the front end of the inner peripheral portion 164a, an inclined surface 164b that is inclined toward the axial center and whose inner diameter is increased toward the front end is formed. The inclined surface 164b is provided in order to make it easier to place the chuck body 163 in the chuck ring 164 and to prevent the chuck body 163 from being damaged such as a dent. The formation part of this inclined surface 164b may be formed not in an inclined surface but in the circular arc shape bulging outside.

Since the chuck body 163 and the chuck ring 164 are formed as described above, when the chuck body 163 grips the core and is fastened to the chuck ring 164 as shown in FIG. The front end of the peripheral portion 164a serves as a contact point 163g with the inclined surface 163d of the chuck body 163. Let D be the length from the front end of the chuck body 163 to the rear end of the inclined surface 163d. Further, K is the length from the contact point 163g to the rear end of the inclined surface 163d. The length K is such that the front end of the inner peripheral portion 164a of the chuck ring 164 slides on the inclined surface 163d of the chuck body 163 until the chuck body 163 grips the core and is fastened to the chuck ring 164. Represents a range. The final point is the contact point 163g.
Here, the ratio K / D is desirably in the range of 14% or more and less than 30%. The ratio K / D is a range in which the chuck body 163 is fastened to the chuck ring 164 with respect to the outer peripheral portion 163b of the chuck body 163. If this ratio K / D is large, it means that the length K is long, and the gripping force with which the chuck body 163 grips the lead becomes strong, and damage (problem load) is likely to be given to the lead. If this ratio K / D is small, it means that the length K is short, the gripping force for gripping the core of the chuck body 163 becomes weak, and the core is retracted during writing. More specifically, when the ratio K / D is 30% or more, the gripping force for gripping the core of the chuck body 163 becomes strong, and damage (excessive load) is easily applied to the core. On the other hand, if it is less than 14%, the gripping force for gripping the core of the chuck body 163 becomes weak and the core is retracted during writing. Therefore, by setting the ratio K / D in the range of 14% or more and less than 30%, it is possible to prevent the biting (breaking) of the core due to the impact force when the protruding state of the mechanical pencil unit is released.

  Here, since the tip member 167 of the mechanical pencil unit 16S protrudes from the tip of the shaft body 1 and is easy to visually recognize, it is preferable to plate the metal material, and the joint member 162 and the guide tube 165 have a core to be described later. Since they slide on each other by the feeding operation, it is preferable to use polyacetal, nylon resin, or the like having lubricity. In this case, the joint member 162 and the guide tube 165 may be made of the same resin. However, when the resin is different, for example, polyacetal or nylon resin, the slidability of the core feeding operation is improved. When using the same resin, use different grades. Thus, by making a hardness difference between the members that slide with each other, the slidability is improved.

The configuration of each member constituting the mechanical pencil unit 16S will be described in detail.
The lead tank 161 and the joint member 162 are connected by a connecting portion 162a provided behind the joint member 162 being fitted into the lead tank 161, and the fitting is provided in front of the connecting portion 162a. When the front end portion of the core tank 161 comes into contact with the end surface of the rear step portion 162bA of the large diameter portion 162b, the fitting is completed.
The guide cylinder 165 has a rear portion outer shape formed by a large diameter portion 165a and a tapered portion 165b having a reduced diameter rearward in order toward the rear. The outer diameter of the rear end of the tapered portion 165b is larger than the reduced diameter portion 162c of the joint member 162, and is substantially the same as the outer diameter of the large diameter portion 162b of the joint member 162. The tapered portion 165b is formed so that the front end portion 16Bf of the ink storage tube 16Ba can be smoothly stored so as not to be caught by the guide tube 165 when the mechanical pencil unit 16S described later is stored in the shaft body 1. Has been. That is, when the mechanical pencil unit 16S is housed in the shaft body 1, the slider 11B is pressed by causing the release protrusions 13 and 14 formed on the back surfaces of the sliders 11S and 11B to collide with each other. 11S is disengaged. At this time, since the slider 11B slightly presses the slider 11S which is another slider, the pressed writing body may advance by that amount and come into contact with the guide cylinder. However, even if another cursive body comes into contact with the guide cylinder of the mechanical pencil unit, the taper portion 165b is present, so there is no rubbing resistance due to the front end portion 16Bf of the ball pen refill 16B, and the backward movement of the mechanical pencil unit 16S. (Storing) can be performed smoothly. In addition, it is good also considering the back of the taper part 165b of the said guide cylinder 165 as the small diameter part formed continuously from the taper part 165. FIG.
Furthermore, the elastic member 166 rubs against other writing bodies in the process of moving in and out of the mechanical pencil unit 16S and in the process of feeding out the core, and the sliding operation feeling becomes worse or the operation suddenly becomes heavy. In order to prevent this, it is preferable to arrange the guide tube 165 inside.

  Next, the connecting portion between the mechanical pencil slider 11S and the mechanical pencil unit 16S (core tank 161) will be described in detail. The connecting portion 21 of the slider 11S is inserted into the rear end portion of the lead tank 161, and the inclined surface 22a of the front tube portion 22 and the lead tank 161 are interposed between the front tube portion 22 and the lead tank 161 of the slider 11S. A front space 26 is formed by the inner surface. In addition, by setting the outer shape of the rear cylinder portion 25 to be smaller than the inner shape of the core tank 161, the rear space portion 27 is formed with each dimensional difference. A gap 30 is formed at the rear end of the slider 11S and the lead tank 161. In this state, the outside of the core tank 161 near the groove 23 of the slider 11S is caulked so as to be reduced in the radial direction (caulking portion 28). The caulking portion 28 is caulked circumferentially in this example, but may be caulked partially. The core tank 161 is fixed by this caulking portion 28 without dropping from the slider 11S. Further, the inner surface of the core tank 161 and the rear end portion of the front cylindrical portion 22 are in point contact since the shape of the rear end portion is an octagon. Further, the mechanical pencil unit 16S is rotatably connected by the front space portion 26, the rear space portion 27, and the gap 30. Here, the front cylinder portion 22 of the slider 11S is inclined by reducing the diameter toward the front, but this is a guide portion when the lead tank 161 is inserted. By securing the length of the front cylindrical portion 22 to some extent, it plays a role as an inner surface guide when caulking the lead tank 161 at the same time as the guide when the lead tank 161 is inserted. The clearance 30 is set so that the mechanical pencil unit 16S can be rotated with respect to the slider 11S, and the rear end surface of the lead tank 161 is not in contact with the rear end surface of the connecting portion 21 of the slider 11S during the rotation. Has been. As a result, the mechanical pencil unit 16S can be smoothly rotated, and the in / out operation can be easily performed. Further, the rotation range of the mechanical pencil unit 16 </ b> S is regulated by the rear end inner surface of the lead tank 161 contacting the surface of the rear cylinder part 25. When the slider 11S is pressed forward by this contact, the inner surface portion of the rear end of the lead tank 161 acts so as to bite the rear cylinder portion 25, and the mechanical pencil is surely moved without losing the forward movement of the slider 11S. It can be transmitted to the unit 16S (core tank 161).

The configuration of the connecting portion between the mechanical pencil slider 11S and the mechanical pencil unit 16S (core tank 161) is not limited to the point contact configuration described above.
For example, the lead tank 161 is bent in the vicinity of the connecting portion 21 in front of the mechanical pencil slider 11S (bending portion 161b; see FIGS. 23A and 23B) and mounted on the shaft body 1. The front part of the mechanical pencil unit 16S may be directed in the direction of the central axis of the shaft body 1. In this case, the lead tank 161 may be detachably fixed to the connecting portion 21 of the slider 11S by means such as adhesion.
Further, a core tank 161 of a cylindrical mechanical pencil unit 16S made of a resin material such as polypropylene or nylon or a metal material is connected to the connecting portion 21 by a caulking process (caulking portion 161a) in a non-rotatable manner. good. The caulking portion 161a is formed over the circumference. Of course, it may be caulked from a plurality of directions and can be appropriately selected. It may be detachable and inserted so as not to rotate.
Alternatively, the connecting portion 21 may be bent so that the front of the mechanical pencil unit 16S is directed toward the center (see FIGS. 24 and 25). More specifically, the connecting part 21 of the slider 11S is bent at an angle with respect to the rear base part excluding the connecting part 21 of the slider 11S.

Next, the operation will be described with reference to FIGS. 3, 26 to 29, and 33. When the slider 11S is pressed forward (in the diagonally upper left direction in FIG. 26), the slider 11S is guided by the slit 6 and the sliding groove 7 and the slit 6a of the rear shaft 3, and the mechanical repelling member 17S is compressed and deformed while the mechanical pencil is being deformed. It advances with the unit 16S, and the tip of the mechanical pencil unit 16S protrudes from the tip of the shaft body 1 (see FIG. 28). At the same time, the slider 11S is pushed in the axial direction, which is the inner side of the rear shaft 3, but the flange portion 11Sd abuts on the outer peripheral surfaces on both sides of the slit 6 of the rear shaft 3, and the pushing of the slider 11S is restricted. Next, the rear end (upward in FIG. 27) of the sliding protrusion 12 formed on the side surface portion of the slider 11S engages with the front end portion of the sliding groove 7 to prevent the mechanical pencil unit 16S from retreating, The forward position of the mechanical pencil unit 16S is maintained. That is, by forming the sliding groove 7 only up to the middle portion of the slit 6, the slider 11S is also engaged.
In the projecting process of the mechanical pencil unit 16S, the rear portion of the slider 11S sinks in the direction of the central axis of the shaft main body 1, and the front portion of the mechanical pencil unit 16S attempts to approach the inner wall surface of the shaft main body 1. Since the mechanical pencil unit 16S is rotatably connected at the rear part thereof, the front part of the mechanical pencil unit 16S protrudes while maintaining a straight line.
Here, as described above, the elastic member 17S of the mechanical pencil unit 16S has a lower spring constant than the elastic member 17B of the ballpoint pen refill 16B, and thus is stronger than the elastic member 17B of the ballpoint refill 16B ( (Load) becomes low. Therefore, the operational feeling when the mechanical pencil unit 16S protrudes from the shaft body 1 is lighter than the operational feeling when the ball pen refill 16B protrudes from the shaft body 1. As described above, the difference in the writing style can be easily identified by using the ball pen refill 16B and the mechanical pencil unit 16S with different operational feelings during the protruding operation, and the dual writing instrument can be easily used.
Further, the mechanical pencil unit 16S is more advanced than the ballpoint pen refill 16B from the forward position where the tip of the mechanical pencil unit 16S protrudes from the distal end of the shaft body 1, and the lead for pressing the slider 11S in the forward direction. The operation is necessary, and the distance (stroke) and the number of times that the elastic member 17S is biased (compressed) are large. Therefore, since the spring load can be lowered when the spring constant is smaller, the lead knocking pressure of the lead is lowered and the operation becomes easier.
A distance from the front end portion of the tip member 4 to the front end portion (stepped portion) 16Bf of the ballpoint pen refill 16B in the immersed state is A.
Here, when the upper end 11Se of the flange portion 11Sd of the slider 11S is pressed forward in the forward position where the tip of the mechanical pencil unit 16S protrudes from the tip of the shaft body 1, the tip member 167 of the mechanical pencil unit 16S is The tip member 4 abuts on the conical portion 4a whose diameter gradually decreases toward the tip end side of the inner diameter portion, and the mechanical pencil unit 16S is prevented from moving forward. The outer peripheral surface of the tip member 167 has a plurality of step portions, and the outer diameter of the tip member 167 on the rear side is larger than the outer diameter of the tip member 167 on the front side in each step portion. . For this reason, when the mechanical pencil unit 16S is advanced, the tip member 167 of the mechanical pencil unit 16S comes into contact with the tip member 4 of the shaft body 1. Here, when the slider 11S is further pressed, the lead tank 161 and the chuck body 163 move forward against the elastic force of the elastic member 166, and the front step portion 162bB of the large diameter portion 162b is moved to the guide tube 165. When the taper portion 165b comes into contact with the rear end of the taper portion 165b, the forward movement is completed, and this is a stroke of the lead feeding and pressing operation. The reduced diameter portion 162c of the joint member 162 is accommodated inside the guide tube 165 (the distance from the front end of the tip member 4 to the front step portion 162bB of the large diameter portion 162b is B). (FIG. 33)). As a result, the lead is extended. At this time, as described above, the rotation range of the mechanical pencil unit 16S is restricted by the rear end inner surface portion of the lead tank 161 coming into contact with the surface of the rear cylinder portion 25, and this contact pushes the slider 11S forward. When this occurs, the inner surface of the rear end of the lead tank 161 acts so that the rear cylinder part 25 bites, and the forward movement of the slider 11S is reliably transmitted to the mechanical pencil unit 16S (lead tank 161) without loss. It can be done. In the maximum advance state of the mechanical pencil unit when the lead is pushed out, the front step portion 162bB of the mechanical pencil unit is positioned in front of the front end portion (step portion) 16Bf of the ball pen refill 16B. (B <A).
In the course of the center feeding operation, the flange portion 11Sd of the slider 11S is in sliding contact with the outer peripheral surface of the rear shaft 3. In the present invention, when the slider 11S is moved back and forth during the lead feeding operation process, the slider 11B is not involved with the slider 11B of another ballpoint pen refill. That is, the slider 11S and the mechanical pencil unit provided in front of the slider 11S move back and forth independently. For this reason, at the time of the lead feeding operation, the ball pen refill (other writing bodies excluding the mechanical pencil unit) does not move slightly back and forth. When the lead of the mechanical pencil unit is extended, only the mechanical pencil unit moves back and forth with respect to the shaft body 1. As described above, only the mechanical pencil unit moves back and forth with respect to the shaft main body 1, so that the core feeding operation load does not increase and a satisfactory core feeding operation can be performed.

Next, when the mechanical pencil unit 16S is to be stored in the shaft body 1, the other slider 11B is pressed. When the other slider 11B is pressed, the release protrusions 13 and 14 formed on the back surfaces of the sliders 11S and 11B collide with each other. By this collision action, the slider 11 </ b> S being pressed is pressed toward the outside of the rear shaft 3. Then, by this pressing action, the engagement between the sliding projection 12 and the sliding groove 7 of the slider 11S is released, and the mechanical pencil unit 16S which is in the protruding state by the releasing action is caused by the action of the elastic member 17S. The slider 11S moves backward and is immersed in the shaft body 1, and the slider 11S returns to the original retracted position.
FIG. 26B illustrates a state in which the slider 11S has advanced. In this state, the rear shaft 3 has a large space portion including the slit 6 and the narrow slit portion 6a. In this state, as a matter of course, if the lead feeding operation is further performed, foreign matter such as dust and dirt can easily enter the space. As a result, foreign matter such as dust and dust is likely to stick to the wall surfaces of the slit 6 and the narrow slit portion 6a and the slide surface 3a.
However, since the slit 6 is close to the outer peripheral surface, it is easy to remove foreign matters such as dust and dust, and since the slide surface 3a slides while the back surface of the sliding projection 12 is in contact, foreign matters such as dust and dust are easily scraped off. It has become. However, since the narrow slit portion 6a is located in the vicinity of the axial center, it is difficult to remove foreign matters such as dust and dirt. Therefore, in the present embodiment, the hole 11Sf of the slider 11S is removed so as to scrape off dust and dirt from the narrow slit portion 6a by the retreating operation of housing the mechanical pencil unit 16S in the shaft body 1, and the hole 11Sf. The foreign material scraped off is stored. And after storing, it discharges | emits from the part exposed from the narrow slit part 6a of the hole 11Sf.

In the process of the lead-out operation of the mechanical pencil unit 16S, the important step is that the mechanical pencil unit 16S is in a forward step portion of the large-diameter portion 162b of the joint member 162 when the mechanical pencil unit 16S is in the maximum advance state during the lead-out pushing operation. The configuration is such that 162bB is positioned in front of the front end portion (step portion) 16Bf of the ink containing tube 16Ba (B <A). That is, the maximum advance state of the mechanical pencil unit during the lead-out pushing operation of the lead in the lead-out operation of the mechanical pencil unit 16S, rather than the distance A from the front end of the tip part 4 of the stepped portion 16Bf of the immersion ball refill. At this time, the distance B from the front end portion of the front member of the front step portion 162bB of the mechanical pencil unit 16S is smaller (see FIG. 33). This is because the taper unit 165b having a larger outer diameter than the front step portion 162bB of the large-diameter portion 162b abuts and interferes with the front end portion 16Bf, so that the mechanical pencil unit 16S is bent and the centering operation is deteriorated. This is to prevent this.
As described above, the lead-out operation is performed by pressing the upper portion 11Se of the flange portion 11Sd of the slider 11S in the forward direction at the forward movement position where the tip of the mechanical pencil unit 16S protrudes from the tip of the shaft body 1. The tip member 167 of the pencil unit 16S comes into contact with the conical portion 4a whose diameter gradually decreases toward the distal end side of the inner diameter portion of the tip member 4, and the forward movement of the mechanical pencil unit 16S is prevented. Here, when the slider 11S is further pressed, the lead tank 161 and the chuck body 163 move forward against the elastic force of the elastic member 166, and the front step portion 162bB of the large diameter portion 162b is moved to the guide tube 165. When the taper portion 165b comes into contact with the rear end of the taper portion 165b, the forward movement is completed, and this is a stroke of the lead feeding and pressing operation. The reduced diameter portion 162c of the joint member 162 is just accommodated inside the guide tube 165 (see FIG. 33). As a result, the lead is extended. Therefore, in the course of the lead feeding operation, the taper unit 165b abuts and interferes with the front end portion 16Bf to prevent the mechanical pencil unit 16S from being bent and the lead feeding operation from being deteriorated. Operation can be obtained.
A step portion is formed on the tip member 167, but since it is a tip portion, it does not rub against other cursive bodies. (See Figure 29)

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to only the following Examples.
(Examples 1-5)
For the length D from the front end of the chuck body 163 to the rear end of the inclined surface 163d, three levels of 1.52 mm, 1.67 mm, and 1.82 mm are prepared.
The combination with the chuck ring 164 is set so that the length K from the contact point 163g to the rear end of the inclined surface 163d is 0.25 mm, 0.35 mm, 0.47 mm, and 0.50 mm. The combinations are as shown in Table 1.

(Comparative Examples 1-4)
For the length D from the front end of the chuck body 163 to the rear end of the inclined surface 163d, two levels of 1.52 mm and 1.67 mm are prepared.
The combination with the chuck ring 164 is set so that the length K from the contact point 163g to the rear end of the inclined surface 163d is 0.20 mm, 0.47 mm, and 0.62 mm. The combinations are as shown in Table 1.

The mechanical pencil unit incorporating the chuck body 163 and the chuck ring 164 produced in Examples 1 to 5 and Comparative Examples 1 to 4 is assembled. A core breaking test and a pressure resistance test of the core were carried out with a compound writing instrument incorporating these mechanical pencil units. These results are shown in Table 1.

(1) In the core breakage test, the mechanical pencil unit cursive is locked and released 30 times continuously by operating the slider of the mechanical pencil unit cursive and the slider of another ballpoint pen refill. Then, knock the slider of the mechanical pencil unit cursive to align the core, and check for broken cores.
A: No core breakage (40 times or more).
○: No core breakage.
X: There is a broken core.
XX: There is a broken core (within 15 times).
(2) In the lead pressure test (prevention of lead withdrawal), about 1 mm of the lead is taken out and a vertical compression load is applied to the lead using a stand alone. At 6N (600 gf), it is confirmed whether or not the core is also inserted into the tip member.
○: No core retraction (800 gf or more).
○: No core retraction.
X: Recessed core.
XX: Recessed core (within 300 gf).

  From the above results, it can be seen that the K / D ratio in the range of 14% or more and less than 30% is good in evaluation, and more preferably in the range of 26% or more and 28% or less. Thereby, it turns out that the bite cutting (breaking) of the core by an impact force can be prevented. That is, even if the contact point S between the chuck body and the chuck ring is shifted due to the impact force, an excessive lead gripping force is not applied to the lead, and the lead is not damaged. This can prevent the composite writing instrument from being used.

1 Shaft body (shaft tube)
2 Front shaft 3 Rear shaft 3a Sliding surface 4 Tip member 4a Conical portion 4b Projection hole 4c Plane portion 5 Middle shaft 6 Slit 6a Slit 7 Sliding groove 8 Leg portion 9 Clip portion 10 Ball portion 11 Slider 111 Extension portion 11B For ball pen refill Slider 11S slider for mechanical pencil unit 11Sd flange 11Se upper part 11Sf hole 11Sg arc part 11a hole 11b plane part 11c arcuate curved part 11d extension part 12 sliding protrusion 13 release protrusion 14 release protrusion 15 connecting part 15a rear part 15b Front part 15c Large diameter part 15d Fitting protrusion 15e Flat part 15f Projection 15g Projection 16B Ballpoint pen refill 16Ba Ink storage tube (pipe part)
16Bb ballpoint pen tip (writing part)
16Bc bulging part 16Bd bulging part 16Be inner surface shape 16Bf front end part (step part)
16S mechanical pencil unit 161 core tank 161a caulking portion 161b bent portion 162 joint member 162a connecting portion 162b large diameter portion 162bA rear step portion 162bB front step portion 162c reduced diameter portion 163 chuck body 163a horizontal grip portion 163b outer periphery portion 163b outer periphery portion 163b outer periphery portion 163b Surface 163e Guide inclined surface 163f Body diameter portion 163g Contact point 163h Taper portion 163i Through hole 164 Chuck ring 164a Inner peripheral portion inclined surface 164b Inclined surface 165 Guide tube 165a Large diameter portion 165b Taper portion 166 Rebound member 167 Lead member 16 Stop member 17 Repellent member 17B Repellent member 17S Repellent member 18 Connecting portion 19 Through hole 20 Groove portion 21 Connecting portion 22 Front cylinder portion 23 Groove portion 24 Inclined surface 25 Rear cylinder portion 26 Front space portion 27 Back space 28 caulking portion 30 gap

Claims (2)

A writing instrument in which a mechanical pencil unit having a chuck body that grips and releases a lead and a chuck ring that surrounds the front of the chuck body and opens and closes the chuck body is arranged to be able to appear and retract in a shaft cylinder. The outer peripheral portion corresponding to the core gripping portion of the body is formed of at least a horizontal portion substantially parallel to the axis, and an inclined portion that is located behind the horizontal portion and is inclined in the axial direction. An inner peripheral portion of the ring is formed substantially parallel to the axis, the chuck body is fitted to the chuck ring, and a sliding region in which the chuck ring slides with the chuck body when gripping the core is defined as K. Writing with which a mechanical pencil unit can appear and disappear, wherein the ratio K / D is 14% or more and less than 30%, where D is the length from the front end of the body to the rear end of the inclined surface. . The writing instrument in which the mechanical pencil unit according to claim 1 can be projected and retracted, wherein an R portion is formed from a front end of the chuck body to a front end of a core gripping portion of the chuck body.

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