JP6789045B2 - Multi-core writing instrument - Google Patents

Description

The present invention relates to a multi-core writing instrument having a plurality of refills.

A multi-core writing tool having a plurality of refills and capable of selectively appearing a desired refill is known (Patent Document 1). A spacer is arranged in the shaft cylinder of the multi-core writing instrument of Patent Document 1. A plurality of through holes extending in the axial direction are formed in the spacer, and a plurality of refills are inserted into the through holes so as to be aligned along the circumferential direction at predetermined intervals.

Japanese Unexamined Patent Publication No. 2013-0821172

In general, a multi-core writing tool needs to arrange a plurality of refills in parallel in one barrel, so that the outer diameter of the barrel, that is, is inevitably compared with a writing tool having only one refill. The shaft diameter becomes thick.

Further, in the multi-core writing tool of Patent Document 1, when exchanging a new refill, it is necessary to insert the refill into the through hole of the spacer from the front end opening of the rear shaft from which the front shaft has been removed. However, since the through hole of the spacer is arranged away from the front end opening, the user needs to work while looking into the inside from the front end opening of the rear axle, which makes it difficult to insert the refill. .. Further, since the inner diameter of the through hole of the spacer is slightly larger than the outer diameter of the refill and is very small, the insertion work is made more difficult while looking into it.

An object of the present invention is to provide a multi-core writing tool capable of easily performing a refill replacement operation. Furthermore, an object of the present invention is to provide a multi-core writing instrument having a shaft diameter smaller than that of the conventional one.

According to one aspect of the present invention, a barrel provided with a front shaft and a rear shaft, a plurality of refills, and a spacer protruding forward from the rear shaft are provided, and the spacer extends in the axial direction. Further, a plurality of guide grooves or through holes into which each of the refills is inserted are formed, and the outer peripheral surface of the spacer engages with the inner peripheral surface of the front shaft, whereby the front shaft and the rear shaft are formed. A multi-core writing tool is provided in which a male screw portion is formed on the outer peripheral surface of the spacer, and the spacer engages with the front shaft by screwing.

Further, according to another aspect, a multi-core writing instrument in which the spacer is a separate body from the rear shaft is provided.

According to the aspect of the present invention, the common effect that the refill replacement work can be easily performed is obtained.

It is a vertical sectional view of the multi-core type writing instrument according to the embodiment of this invention. It is a perspective view of the multi-core type writing instrument with the front shaft removed. It is a perspective view of the multi-core type writing instrument with the front shaft and the rear shaft removed. It is a perspective view of a spacer. It is sectional drawing in line XX of FIG. It is a vertical sectional view of a rear axle. It is the schematic explaining the heat shrinkage of the column of the conventional spacer. It is the schematic explaining the heat shrinkage of the column of a spacer. It is the schematic which shows the relationship between the spacer and the knock member in a non-writing state. It is the schematic which shows the movable range of a coil spring. It is the schematic which shows the relationship between a spacer and a coil spring. It is the schematic which shows the connection part of the front shaft and the rear shaft.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. A common reference code is attached to the corresponding components throughout the drawings.

FIG. 1 is a vertical sectional view of a multi-core writing instrument 1 according to an embodiment of the present invention. The multi-core writing instrument 1 includes a shaft cylinder 4 having a front shaft 2 and a rear shaft 3 and formed in a cylindrical shape as a whole, and three refills 6 having a writing portion 5 and housed in the shaft cylinder 4. It has three knock members 7 to which the front end is connected to each rear end of the refill 6, three coil springs 8 to which each of the refill 6 penetrates the inside, and a spacer 20. A hole 9 for projecting the writing portion 5 of the refill 6 is formed at the front end of the front shaft 2.

In the present specification, in the axial direction of the multi-core writing instrument 1, the writing portion 5 side is defined as the "front" side, and the side opposite to the writing portion 5 is defined as the "rear" side. Further, the "axis" or "central axis" means the central axis of the multi-core writing instrument 1 unless otherwise specified.

On the outer peripheral surface of the rear end portion of the rear shaft 3, three window holes 10 extending in the axial direction are formed at equal intervals around the central axis. A knock member 7 is arranged in each window hole 10. The knock members 7 are arranged at equal intervals around the central axis corresponding to the window holes 10. The knock member 7 can move back and forth in the window hole 10 along the axial direction. The writing portion 5 of the refill 6 protrudes or retracts from the front end of the axle cylinder 4, that is, the hole 9 of the front shaft 2, according to the front-back movement of the knock member 7. Here, the state in which the writing unit 5 protrudes from the barrel 4 is referred to as a writing state, and the state in which the writing portion 5 is immersed in the barrel 4 is referred to as a non-writing state (FIG. 1).

In the multi-core writing instrument 1, a known knock mechanism selectively switches between a writing state and a non-writing state in response to a knocking operation of pressing the knock member 7 forward. That is, three rails 11 extending in the axial direction are formed on the inner peripheral surface of the rear end portion of the rear shaft 3, and each of the knock members 7 can slide in the front-rear direction along the rails 11 between the rails 11. Is located in. The knock member 7 and the refill 6 connected to the knock member 7 are urged rearward by the coil spring 8.

In order to switch from the non-writing state to the writing state, the knock member 7 to which the desired refill 6 is connected is slid forward against the urging force of the coil spring 8 by the knock operation. When the knock member 7 is slid beyond the rail length of the rail 11, the knock member 7 is separated from the tip of the rail 11. At this time, the knock member 7 enters the shaft cylinder 4 in the direction orthogonal to the central axis, that is, in the radial direction. Next, when the rear end of the knock member 7 engages with the tip of the rail 11 by the urging force of the coil spring 8, the writing portion 5 of the refill 6 protrudes from the hole 9 at the front end of the barrel 4, and the writing state is established. ..

On the other hand, in order to switch from the writing state to the non-writing state, the knock member 7 other than the knock member 7 corresponding to the refill 6 in the writing state is slid forward against the urging force of the coil spring 8 by the knock operation. Let me. In the process of sliding along the rail, the knock member 7 collides with the knock member 7 in the writing state and disengages the knock member 7 from the rail 11. As a result, the urging force of the coil spring 8 causes the refill 6 connected to the knock member 7 to retract, and a non-writing state is established.

FIG. 2 is a perspective view of the multi-core writing instrument 1 with the front shaft 2 removed, and FIG. 3 is a perspective view of the multi-core writing instrument 1 with the front shaft 2 and the rear shaft 3 removed. FIG. 4 is a perspective view of the spacer 20, and FIG. 5 is a cross-sectional view taken along the line XX of FIG. Note that FIG. 4A is a perspective view of the spacer 20 viewed from the front side, and FIG. 4B is a perspective view of the spacer 20 viewed from the rear side.

The spacer 20 is integrally formed from a resin material such as ABS resin by injection molding. Further, in the present embodiment, the spacer 20 is separate from the axle cylinder 4, for example, the rear axle 3, but may be integrally formed. That is, since the "spacer" is a space between the refills 6, the coil springs 8, and the other two stele members so as not to interfere with each other, even if they are separate bodies, one of the shaft cylinders. It may be integrally formed inside the portion, for example, the rear shaft 3.

The spacer 20 has a solid spacer body 21. In the present embodiment, the spacer main body 21 is columnar, but may have other column shapes. A plurality of guide grooves 22 extending in the axial direction and into which each of the refills 6 is inserted are formed on the outer peripheral surface of the spacer main body 21. The guide groove 22 is formed from the front end surface to the rear end surface of the spacer main body 21. In the present embodiment, there are three guide grooves 22 corresponding to the number of refills 6, and these are formed at equal intervals around the central axis. The guide groove 22 has an inner surface shape in which the parallel and narrow flat surface portions 23 facing each other are connected to the curved surface portion 24 having a substantially semi-cylindrical shape (FIG. 4). The depth of the guide groove 22 is set to be slightly larger than the diameter of the refill 6 so that the refill 6 can be fitted. Therefore, the outer diameter of the spacer main body 21 is set so as to inscribe the three refills 6 inserted in each guide groove 22. The refill 6 can move in the front-rear direction together with the connected knock member 7 by being guided by the guide groove 22.

On the rear end surface of the spacer main body 21, one central pillar 25 extending rearward along the central axis is formed. Further, on the rear end surface of the spacer main body 21, three columns 26 extending rearward are formed in the vicinity of the outer peripheral edge between the guide grooves 22. Therefore, on the rear end surface of the spacer main body 21, a central pillar 25 and two pillars 26 are arranged around each of the guide grooves 22. The central pillar 25 and the pillar 26 are formed to have substantially the same length. A small arc-shaped support region 27 is formed around the guide groove 22 on the rear end surface of the spacer main body 21 (FIG. 4 (B)).

A coil spring 8 is sandwiched between the rear end surface of the spacer body 21 of the spacer 20 and the knock member 7. That is, the front end of the coil spring 8 is supported by abutting against the support region 27, and the front end of the knock member is inserted into the rear end of the coil spring 8. The rear end portion of the refill 6 penetrating the guide groove 22 is connected to the front end portion of the knock member 7 while being surrounded by the coil spring 8. With these configurations, the knock member 7 is in a rearwardly urged state, and the coil spring 8 generates an elastic force that opposes the force that presses the knock member 7 forward.

As shown in FIG. 5, each of the coil springs 8 is surrounded by the side surface of the central column 25, the side surface of the two columns 26, and the inner peripheral surface of the rear axle 3, thereby regulating the movement in the transverse direction. ing. That is, the movement of the coil spring 8 in the circumferential direction is regulated by the first regulating surface 28 formed on the side surface of the column 26, and the movement of the coil spring 8 in the radial direction is regulated by the side surface of the central column 25. The movement of the coil spring 8 outward in the radial direction is regulated by the second regulating surface 29 formed on the rear shaft 3, and is regulated by the third regulating surface 30 formed on the inner peripheral surface of the rear shaft 3. Each of the first regulation surface 28 and the second regulation surface 29 is curved so as to generally receive the cylindrical coil spring 8. Each of the first regulation surface 28, the second regulation surface 29, and the third regulation surface 30 extends in the axial direction.

Each of the columns 26 is formed in a columnar shape having a substantially triangular cross-sectional shape. The two side surfaces of the support column 26 constitute the first regulation surface 28 as described above, and the remaining one surface is in contact with the inner peripheral surface of the rear axle 3, that is, the fourth regulation surface 35 described later. Since the multi-core writing tool 1 has three refills 6, the central pillar 25 is formed in a columnar shape having a substantially triangular cross-sectional shape. The three sides of the central pillar 25 constitute the second regulatory surface 29 as described above. The central pillar 25 is formed in a columnar shape having a substantially polygonal cross-sectional shape according to the number of refills 6 accommodated in the multi-core writing tool.

In the middle portion of the spacer main body 21, a protruding flange portion 31 is formed over the entire circumference as if an annular ring was fitted. Since the flange portion 31 is formed so as to bridge each of the guide grooves 22, it does not hinder the insertion of the refill 6 into the guide grooves 22. A male screw portion 32 is formed on the outer peripheral surface of the spacer main body 21 in front of the flange portion 31, that is, the outer peripheral surface between the guide grooves 22. The male screw portion 32 of the spacer 20 is screwed with the female screw portion (FIG. 1) formed on the inner peripheral surface of the rear end portion of the front shaft 2. On the other hand, on each of the outer peripheral surfaces of the spacer main body 21 behind the flange portion 31, that is, the outer peripheral surfaces between the guide grooves 22, a plurality of first protrusions 33 arranged along the circumferential direction and in parallel in the axial direction. Is formed. Here, the rear shaft 3 will be described in relation to the plurality of first protrusions 33.

FIG. 6 is a vertical cross-sectional view of the rear axle 3. As described above, the rear shaft 3 is formed with three window holes 10 and three rails 11. Further, on the inner peripheral surface of the rear shaft 3 corresponding to the position where the coil spring 8 is arranged, the above-mentioned three third regulation surfaces 30 are formed in a groove shape extending in the axial direction. A plurality of second protrusions 34 arranged along the circumferential direction and in parallel in the axial direction are formed on the inner peripheral surfaces of the third regulating surfaces 30 near the front end portions. A fourth regulation surface 35 extending in the axial direction is formed behind the plurality of second protrusions 34 between the third regulation surfaces 30.

The first protrusion 33 of the spacer 20 is engaged by getting over the second protrusion 34 of the rear shaft 3. That is, when the spacer 20 is attached to the rear shaft 3, the rear end portion of the spacer 20 is inserted through the front end opening of the rear shaft 3. At this time, the first protrusion 33 of the spacer 20 comes into contact with the second protrusion 34 of the rear shaft 3, but when further inserted, either or both of the first protrusion 33 and the second protrusion 34, or the spacer 20 and the rear One or both of the shafts 3 are elastically deformed, and the first protrusion 33 gets over the second protrusion 34 in the axial direction. As a result, the spacer 20 engages with the rear shaft 3 to the extent that it does not come off the rear shaft 3 by simply pulling it lightly.

When assembling the multi-core writing instrument 1, first, the knock member 7 and the coil spring 8 are arranged in the rear shaft 3, and the spacer 20 is inserted in the rear shaft 3. At this time, the spacer 20 is inserted into and engaged with the rear shaft 3 until the rear end surface of the flange portion 31 comes into contact with the front end surface of the rear shaft 3. Then, each of the guide grooves 22 of the spacer 20 is inserted into the refill 6. At this time, the refill 6 is pushed all the way in until the rear end portion of the refill 6 is connected to the front end portion of the knock member 7. Next, the male threaded portion of the front shaft 2 is screwed into the male threaded portion 32 of the spacer 20 exposed from the front end portion of the rear shaft 3. At this time, the assembly is completed by rotating and screwing the front shaft 2 until the rear end surface of the front shaft 2 comes into contact with the front end surface of the flange portion 31 of the spacer 20.

Here, in the conventional multi-core writing tool as described in Patent Document 1, when the new refill is replaced, the refill is inserted into the through hole of the spacer from the front end opening of the rear shaft from which the front shaft is removed. There is a need. However, since the through hole of the spacer is arranged away from the front end opening, the user needs to work while looking into the inside from the front end opening of the rear axle, which makes it difficult to insert the refill. .. Further, since the inner diameter of the through hole of the spacer is slightly larger than the outer diameter of the refill and is very small, the insertion work is made more difficult while looking into it.

On the other hand, as shown in FIG. 2 and as described above, in the multi-core writing instrument 1, the front portion of the spacer 20 projects forward from the front end opening of the rear shaft 3, and therefore, the guide groove corresponding to the through hole of Patent Document 1 The front part of 22 is exposed to the outside. Therefore, when replacing the refill 6, first, the rear end portion of the refill 6 is arranged at an arbitrary position of the exposed guide groove 22. Then, by pushing the refill 6 backward as it is, the refill 6 can be easily inserted into the rear shaft 3 while being guided along the guide groove 22. As a result, it is not necessary to look into the thin shaft cylinder to find the position of the through hole, and the refill 6 can be easily replaced.

In the present embodiment, a guide groove 22 that opens radially outward is formed on the outer peripheral surface of the spacer 20 that protrudes forward from the rear shaft 3, but instead of the guide groove 22, Patent Document 1 A through hole extending in the axial direction may be formed as described in 1. In that case, the entrance of the through hole is formed on the front end surface of the spacer, but since this is also exposed to the outside, the refill 6 can be easily inserted.

By the way, when a thin beam-shaped member formed so that one end is a free end, such as a support column of a spacer of a multi-core writing instrument of Patent Document 1, is molded with resin, the beam-shaped member is heat-shrinked by cooling after molding. May warp and the intended shape may not be maintained. This will be specifically described with reference to FIG.

FIG. 7 is a schematic view illustrating the heat shrinkage of the columns 126 of the conventional spacer 120. In detail, FIG. 7A is a schematic view of the support column 126 of the spacer 120 immediately after injection molding, and FIG. 7B is a schematic view of the support column 126 of the spacer 120 after being cooled and heat-shrinked. is there. As shown in FIG. 7 (A), two adjacent columns 126 formed in parallel immediately after injection molding have their tips approaching each other due to heat shrinkage, as shown in FIG. 7 (B). It warps. Therefore, it interferes with the coil spring 108 arranged between them, which causes a defective knock operation. A method of suppressing the influence of heat shrinkage will be specifically described with reference to FIG.

FIG. 8 is a schematic view illustrating the heat shrinkage of the support column 26 of the spacer 20 described above. In detail, FIG. 8A is a schematic view of the support column 26 of the spacer 20 immediately after injection molding, and FIG. 8B is a schematic view of the support column 26 of the spacer 20 after being cooled and heat-shrinked. FIG. 8C is a schematic view of a state in which the spacer 20 is attached to the rear shaft 3.

As shown in FIG. 8A, the support column 26 of the spacer 20 is formed in advance assuming deformation due to heat shrinkage, that is, in a deformed shape that deviates from the ideal shape in advance. What is important in the support column 26 of the spacer 20 is to define a space that does not hinder the expansion and contraction of the coil spring 8. Therefore, finally, it is preferable that the surface of the support column 26 facing the coil spring 8, specifically the first regulation surface 28 described above, is parallel to the axial direction of the coil spring 8. Therefore, first, the first regulation surface 28 of the support column 26 is formed so as to warp toward the tip end, in other words, to form a taper shape. As a result, the tips of the two adjacent columns 26 are separated from each other more than the ideal shape and are widened.

After that, as shown in FIG. 8B, the columns 26 are warped in the direction in which their tips approach each other due to heat shrinkage, and the first regulating surface 28 is deformed to the point where it is almost parallel to the axial direction of the coil spring 8. To do. That is, at this point, the tips of the two adjacent columns 26 are slightly separated from each other from the ideal shape. Therefore, when the spacer 20 is inserted into the rear shaft 3 for assembling the multi-core writing instrument 1, the outer surface of the support column 26 of the spacer 20 slides on the fourth regulation surface 35 of the rear shaft 3 in the process of insertion. .. The tips of the columns 26 of the spacer 20 are gradually moved toward each other by sliding on the fourth regulation surface 35, and the columns 26 are corrected to the ideal shape (FIG. 8 (C)). That is, the rear shaft 3, particularly the fourth regulation surface 35, functions as a straightening member that corrects the deformed shape of the support column 26 of the spacer 20 to an ideal shape.

The fourth regulation surface 35 of the rear shaft 3 is formed in a shape surface complementary to the tapered shape of the support column 26 of the spacer 20 in order to enable such correction. That is, the fourth regulation surface 35 is formed as a complementary tapered surface such that the inner part of the rear shaft 3 is closer to the central axis. As a result, the tips of the columns 26 that slide on the fourth regulation surface 35 are pressed in the direction opposite to the warped direction, and are corrected to the ideal shape. Therefore, according to this method, it is possible to provide a writing instrument manufactured as designed and a method for manufacturing the writing instrument.

It should be noted that the configuration having the resin molding member previously molded into a deformed shape deviating from the ideal shape and the straightening member formed so as to correct the deformed shape of the resin molding member into the ideal shape as described above is heat. It can be widely applied to a member using a shrinking resin molded member. Therefore, the present invention is not limited to the production of the support column 26, and can be applied to all members of writing instruments, and further, it can be applied to various other fields such as cosmetics. In this case, the resin molding member is preferably a beam-shaped member.

By the way, in a multi-core writing tool as in Patent Document 1, when the refill is connected to the knock member, when the knock operation is performed, the refill acts as a support and the coil spring is compressed straight along the central axis. To. On the other hand, if a knock operation is performed in a non-writing state without a refill, such as during a refill replacement operation, the coil spring may meander with respect to the central axis of the coil spring during compression. If the coil spring meanders, it will come into contact with the strut or the adjacent coil spring, causing a defective knock operation. This will be described with reference to FIG.

FIG. 9 is a schematic view showing the relationship between the spacer and the knock member in the non-writing state. In detail, FIG. 9A is a schematic view showing the relationship between the conventional spacer 120 and the knock member 107, and FIG. 9B is a schematic view showing the relationship between the spacer 20 and the knock member 7 described above. Yes, no refills are inserted in each coil spring.

Referring to FIG. 9A, the coil spring 108 is surrounded by the side surfaces of the central column 125 of the spacer 120 and the side surfaces of the two columns 126 and the inner peripheral surface of the rear axle (not shown), thereby moving in the transverse direction. Is regulated. However, for the portion of the coil spring 108 that extends rearward beyond the central column 125 and the column 126, that is, beyond the rear end of the spacer 120, the rear end is only supported by the knock member 107. In other words, with respect to the portion of the coil spring 108, the knock portion main body 136 of the knock member 107 is inserted from the rear end of the coil spring 108, and the knock portion main body 136 of the knock member 107 is inserted into the coil spring 108. Cross-sectional movement is restricted only for the part.

Therefore, the portion of the coil spring 108 shown in the range L in FIG. 9A, that is, the portion of the coil spring 108 from the rear end of the spacer 120 to the front end of the knock portion main body 136 is externally regulated. Absent. Therefore, as described above, the coil spring may meander with respect to the central axis of the coil spring during its compression.

On the other hand, referring to FIG. 9B, as described above, the coil spring 8 is surrounded by the side surface of the central column 25 of the spacer 20 and the side surface of the two columns 26 and the inner peripheral surface of the rear shaft 3. It regulates cross-sectional movement. Further, by extending one or both of the central column 25 and the column 26, or the knock member 7, the coil spring 8 extends rearward beyond the central column 25 and the column 26, that is, beyond the rear end of the spacer 20. Is supported by the connecting portion of the knock member 7. That is, the knock portion main body 36, which is the connecting portion of the knock member 7, is inserted from the rear end of the coil spring 8 and extends forward beyond the rear end of the spacer 20. In other words, the front end of the knock portion main body 36 of the knock member 7 is arranged in front of the rear end of the spacer 20. Therefore, since the movement of the coil spring 8 in the transverse direction is restricted over the entire length, the coil spring 8 does not meander even if the knock operation is performed in the non-writing state without the refill 6. ..

Even if there is an unregulated coil spring 8 portion between the front end of the knock portion main body 36 of the knock member 7 and the rear end of the spacer 20 at the position in the axial direction, for example, it is the refill 6 If the outer diameter of the coil spring 8 is about the length of the end turn of the coil spring 8, meandering may be prevented by the rigidity of the coil spring 8 itself. Therefore, as long as the rigidity of the coil spring 8 itself prevents meandering, the front end of the knock portion main body 36 of the knock member 7, that is, the rear end of the spacer 20 may be arranged close to each other at a position in the axial direction. ..

In a multi-core writing instrument, how to reduce the outer diameter of the shaft cylinder, that is, the shaft diameter, that is, thinning the shaft is a general problem. Therefore, in the multi-core writing instrument 1 of the present embodiment, a configuration in which the shaft diameter is reduced will be described below.

FIG. 10 is a schematic view showing a movable range of the coil spring 8. In each of FIGS. 10A to 10C, one great circle outlines the rear axle 3, especially its inner peripheral surface, and three small circles outline the coil spring 8. The broken line around each great circle indicates the boundary D of the movable range of each coil spring 8. Here, the movable range means that the coil spring 8 is within the range regulated by the side surface of the central column 25, the side surfaces of the two columns 26, and the inner peripheral surface of the rear axle 3, that is, the third regulation surface 30 described above. The range that can be moved. In other words, the positions and shapes of the first regulation surface 28, the second regulation surface 29, and the third regulation surface 30 are set so as to be the boundary D of the movable range. In general, the outer diameter of a coil spring increases as it is compressed.

FIG. 10A shows a case where the boundary D of the movable range is set as a circle having a maximum outer diameter d1 when the coil spring 8 is compressed. When the boundary D is set in this way, the inner diameter of the rear shaft 3 can be minimized, and therefore the shaft diameter can also be minimized. However, if the boundary D of the movable range is set based on the maximum outer diameter when the coil spring 8 is compressed, the clearance is completely eliminated and the resistance of the coil spring 8 to the surroundings when expanding and contracting increases. The coil spring 8 cannot be expanded and contracted smoothly.

On the other hand, FIG. 10B shows a case where the boundary D of the movable range is set as a circle having a diameter d2 so as to secure sufficient clearance in all the transverse directions. When the boundary D is set in this way, the shaft diameter cannot be made sufficiently thin.

Therefore, the boundary D is set as shown in FIG. 10 (C). That is, as the boundary D, the circular boundary D having the diameter d2 described above with reference to FIG. 10 (B) is separated by the distance d1 described above with reference to FIG. 10 (A), that is, the concentric circles having the diameter d1. Set so that the shape is defined by the circumscribed line of. More specifically, the position of each of the coil springs 8 is determined so that the center of the coil spring 8 comes so that both ends of the two parallel lines on the central axis side are in contact with each other. Therefore, an equilateral triangle is drawn around the central axis by a part of the boundary D. In the case of the multi-core writing tool 1 having four refills 6, the shape is square. The inner diameter of the rear shaft 3 is determined so that the boundary D is inscribed.

By setting the boundary D as shown in FIG. 10C, the movement of the coil spring 8 in the radial direction is restricted to the distance d1, and the boundary D is restricted to the distance d2 so as to secure a sufficient clearance in the circumferential direction. can do. Therefore, the shaft diameter can be sufficiently reduced while realizing smooth expansion and contraction of the coil spring 8. Any configuration may be adopted as long as the coil spring 8 is configured so that the movement in the radial direction is regulated more than the movement in the circumferential direction in the barrel 4. Therefore, in addition to the shape of the boundary D of the movable range of the coil spring 8 as shown in FIG. 10C, the boundary D may be set so as to have an elliptical shape or an elongated hole shape.

FIG. 11 is a schematic view showing the relationship between the spacer and the coil spring. In detail, FIG. 11A is a schematic view showing the relationship between the conventional spacer 120 and the coil spring 108, and FIG. 11B is a schematic view showing the relationship between the spacer 20 and the coil spring 8 described above. It is a figure, and is the schematic view which looked at the axis tube from the axial direction, respectively.

First, referring to FIG. 11B, as described above, the first protrusion 33 is formed on the outer peripheral surface of the spacer 20, and the engagement is performed by overcoming the second protrusion 34 of the rear shaft 3. , The spacer 20 is attached to the rear shaft 3. The heights of the first protrusion 33 of the spacer 20 and the second protrusion 34 of the rear shaft 3 are substantially the same, and this height portion when the axle cylinder 4 is viewed from the axial direction, that is, the engagement width is defined in the region S. Shown. The spacer 120 shown in FIG. 11 (A) is also engaged in the same manner.

Referring to FIG. 11A, the three coil springs 108 are arranged so as to be included in the outer diameter of the conventional spacer 120. That is, each of the three coil springs 108 is regulated by a central column and three columns (not shown) so as to be included in the outer diameter of the conventional spacer 120, as in the present embodiment described above. Therefore, the shaft diameter is determined by the outer diameter of the spacer 120 not including the height of the protrusion for engagement, the engagement width shown in the above-mentioned region S, and the wall thickness of the rear shaft 103. Therefore, the arrangement of the coil spring 108 is irrelevant to the shaft diameter, and the shaft diameter cannot be reduced.

On the other hand, referring to FIG. 11B, the three coil springs 8 inscribe the first protrusion 33 of the spacer 20 with respect to the circumscribing circle, that is, the region corresponding to the height of the first protrusion 33. It is arranged so as to be inscribed in the outer circle of the region S. Specifically, as described above, the three coil springs 8 are inscribed in the circle circumscribing the first projection 33 of the spacer 20 by the central column 25 and the three columns 26 (not shown here). It is regulated. Therefore, as shown in FIG. 5, each of the coil springs 8 is arranged so as to project radially outward from the adjacent column 26. Therefore, the shaft diameter is determined by the diameter of the circumscribed circle of the three coil springs 8 or the circumscribed circle of the first protrusion 33 of the spacer 20 and the wall thickness of the rear shaft 3, and the engagement shown in the above-mentioned region S. The width can be ignored in determining the shaft diameter. As a result, the shaft diameter can be made sufficiently small.

As another embodiment, at least one coil spring 8 may be inscribed in the circle that circumscribes the first protrusion 33 of the spacer 20. Further, the coil spring 8 may be arranged so as to be inscribed in a circle having an outer diameter of the spacer 20 that does not include the first protrusion 33. In the present embodiment, the first protrusion 33 of the spacer 20 is configured to overcome the second protrusion 34 of the rear shaft 3, but the first protrusion 33 of the spacer 20 is a male screw and the second protrusion 34 of the rear shaft 3 is used. May be a female screw, and the spacer 20 and the rear shaft 3 may be engaged by screwing. In this case, the region S of the engagement width in FIG. 11B described above corresponds to the height of the screw thread.

Such an arrangement of the coil spring 8 can make the shaft diameter smaller by combining with the spacer 20 in which the guide groove 22 is formed as described above. That is, since the guide groove 22 is formed in the spacer 20, the spacer 20 can be thinned as described later, and the effect of thinning the axis by arranging the coil spring 8 is exhibited.

FIG. 12 is a schematic view showing a connecting portion of the front shaft and the rear shaft. In detail, FIG. 12 (A) is a schematic view showing a connection portion of the conventional front shaft 102 and the rear shaft 103, and FIG. 12 (B) shows the connection portion of the front shaft 2 and the rear shaft 3 described above. It is a schematic diagram which shows.

With reference to FIG. 12A, the front shaft 102 is screwed to the rear shaft 103. That is, a male screw is formed on the outer peripheral surface of the rear end portion of the front shaft 102, a female screw is formed on the inner peripheral surface of the front end portion of the rear shaft 103, and these female screws and the male screw are screwed together. As a matter of course, the outer peripheral surface of the front shaft 102 and the outer peripheral surface of the rear shaft 103 need to be formed flush with each other, and the strength also needs to be ensured. Therefore, the wall thickness of the axle tube of the screwed portion, that is, the wall thickness of the rear end portion of the front shaft 102 in FIG. 12 must be formed to be thicker by that amount, for example, twice the wall thickness of the other parts. It doesn't become. As a result, the shaft diameter also becomes large. If the wall thickness of the screwed portion is to be the same as that of other parts, it is necessary to reduce the wall thickness of the male screw portion or the female screw portion. As a result, the strength of the screwed portion is weakened, and the front shaft 2 or the rear shaft 3 is easily cracked.

On the other hand, referring to FIG. 12B, as described above, the front shaft 2 and the rear shaft 3 are connected via the spacer 20. That is, since the spacer 20 has a male screw portion 32 that is screwed with the female screw portion of the front shaft 2, it does not increase the wall thickness of the front shaft 2, and the second protrusion of the rear shaft 3 Since it has the first protrusion 33 that fits with 34, it does not increase the wall thickness of the rear shaft 3. Therefore, the shaft diameter can be reduced by engaging the outer peripheral surface of the front portion and the outer peripheral surface of the rear portion of the spacer 20 with the inner peripheral surface of the front shaft 2 and the inner peripheral surface of the rear shaft 3, respectively. ..

Further, the spacer 20 inserts the refill 6 into the guide groove 22 formed on the outer peripheral surface, and has a diameter in the through hole into which the refill is inserted, as in the multi-core writing tool described in Patent Document 1. The shaft diameter can be reduced by the thickness outside the direction. That is, the outer diameter of the spacer main body 21 is set so as to inscribe the three refills 6 inserted in each guide groove 22, and the spacer 20 itself is not configured to increase the shaft diameter. Further, the spacer 20 has an inevitable configuration in the multi-core writing instrument 1 in the first place, and is intended to utilize it. Therefore, by connecting the front shaft 2 and the rear shaft 3 via the spacer 20, the shaft diameter can be reduced.

According to this thinning configuration, it is possible to realize thinning without reducing the wall thickness of the front shaft 2 or the rear shaft 3 which reduces the strength. In addition, the connection by screwing the front shaft 2 and the spacer 20 may be a connection such as the connection of the rear shaft 3 and the spacer 20 so as to get over the protrusions and engage with each other.

In the above-described embodiment, the multi-core writing tool 1 has three refills 6, but may be two or four or more, and one of them is sharpened instead of the ballpoint pen refill. It may be a pencil or other type of refill. Further, in the above-described embodiment, the multi-core writing instrument 1 is a knock type, but it may be a rotary feeding type in which the refill appears and disappears by rotating the front shaft or the rear shaft around the central axis.

Although various characteristic configurations of the multi-core writing instrument 1 have been described above, these characteristic configurations can be applied as independent configurations or arbitrarily combined configurations.

1 Multi-core writing tool 2 Front shaft 3 Rear shaft 4 Shaft cylinder 6 Refill 7 Knock member 8 Coil spring 20 Spacer 22 Guide groove 25 Stele 26 Strut 32 Male screw part 33 1st protrusion 34 2nd protrusion 36 Knock part body

Claims (2)

It is provided with an axle cylinder having a front shaft and a rear shaft, a plurality of refills, and a spacer protruding forward from the rear shaft.
The spacer is formed with a plurality of guide grooves extending in the axial direction and into which each of the refills is inserted.
By engaging the outer peripheral surface of the spacer with the inner peripheral surface of the front shaft, the front shaft and the rear shaft are connected to each other.
A multi-core writing instrument characterized in that a male screw portion is formed on the outer peripheral surface of the spacer, and the spacer engages with the front shaft by screwing. The multi-core writing instrument according to claim 1, wherein the spacer is separate from the rear shaft.

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