JP2002205493A - Duplex writing utensil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the erasability suitable for the kind of color of a mechanical pencil lead and the kind of ink of a ball point pen by a method wherein a plurality of exclusive erasers are employed in a duplex writing utensil. SOLUTION: In the duplex writing utensil, in the barrel of which a plurality of mechanical pencil writing bodies or a plurality of writing bodies including at least one mechanical pencil writing body are loaded so as to allow to selectively retract and extend the tip of respective writing body from and to the tip opening of the barrel, on the side of a barrel provided at the rear of the barrel, slits extending longitudinally to its rear end are bored at a plurality of spots. In addition, eraser holders provided integral with sliders piercingly projecting to the slits and respectively independently provided on the side. Independent erasers are fixed to the respective eraser holders so as to retract and extend the rear end part of the eraser fixed to the eraser holder from and to the rear end of the barrel by sliding the selected slider along the slit back and forth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-type writing instrument with an eraser feeding device in which an eraser feeding device is connected to the rear end of a writing mechanism.

[0002]

2. Description of the Related Art Conventionally, a mechanical pencil or at least one
2. Description of the Related Art There is known a writing instrument in which a plurality of writing instruments each having a mechanical pencil as a pencil is mounted, and an eraser feeding device is connected to a rear end of a double writing instrument which allows a writing tip to be selectively protruded and retracted from an axis. Such an eraser feeding device has a structure in which the eraser can come out from the rear end by rotating the shaft cylinder of the eraser feeding device or the crown provided at the rear end of the shaft cylinder with respect to the connected writing instrument part. It has been known. Also, with another structure, a slit is provided in the axial direction on the side surface of the shaft cylinder as in the present application, and the slider provided through the slit is slid along the slit, thereby being provided integrally with the slider. There is a known type in which an eraser holder is moved back and forth so that an eraser fixed to the eraser holder is protruded and retracted from the rear end of a shaft cylinder.

[0003] Also, as a mechanical pencil writing material, a colored sharp core is known, in which a porous baked core is impregnated with a dye or pigment ink without using wax or the like, and a writing line can be easily erased with an eraser. I have. However, even with such a colored sharp core, some of the colors have insufficient erasing properties.

[0004] In addition, conventionally known oil-based ballpoint pen inks have a high viscosity as a ballpoint pen writing body, and have the problems of writing, uneven writing lines, low density, and high writing pressure during writing. In addition, although it is a relatively low-viscosity ink as an improvement of the conventional oil-based ballpoint pen, it is filled with a water-based ink that has a so-called shear-thinning property. Known ballpoint pens are known. In such a ball-point pen, when writing upward, if the ink on the back side of the tip ball runs out, there is a danger that the hand or clothes will be stained due to a remarkable backflow due to the direct application of the ink head. In addition, since the viscosity of the ink is low and the amount of outflow is large, if the tip side faces downward and a gap is formed between the tip ball and the tip holding portion, the ink may bleed (direct current). That is, if the tip of the tip is in contact with the cloth, there is a problem that the ink is sucked out and the cloth is soiled. Further, there is a problem that the ink on the back surface of the tip ball tends to flow backward after upward writing or after an impact such as knocking or dropping, so that writing blur occurs. (The tip of the water-based ballpoint pen has a larger vertical play between the tip ball and the tip holding portion than the tip of the oil-based ballpoint pen.) Therefore, it usually follows the consumption of ink when writing at the rear end of the ink. A grease-like follower that suppresses the backflow of the ink against its own weight or impact is provided. Means for pressing the back surface of the tip ball with a spring so that the tip ball is in close contact with the ball holding portion of the chip, and means for providing a valve chamber in which a ball valve is loosely fitted at the rear end of the tip are used.

On the other hand, a ballpoint pen of low viscosity oil-based ink has been considered as an improvement of the conventional ballpoint pen of high viscosity oil-based ink. When a low-viscosity oil-based ink is used, there is no problem of drying of the tip of the chip. Further, the vertical play between the tip ball and the tip holding portion can be reduced as compared with the water-based ballpoint pen, which is advantageous for direct current of ink. When the tip ball diameter is 0.5 mm or less (for fine characters of 0.3 mm and 0.4 mm), the amount of ink flowing out is small and the ink flow path in the chip is narrow, which is advantageous for preventing direct current and reverse flow of ink. is there.
Further, the shorter the length of the ink containing tube (the length of filling of the ink) and the smaller the inner diameter of the ink containing tube, the more advantageous in preventing direct current and backflow of the ink. Based on the above,
Using a low viscosity oil-based ink, reduce the outer diameter of the ink storage tube to 3 ~
3.5mm and ball diameter of 0.5mm or less make it possible to use ballpoint pen as a replacement for ballpoint pen for compound writing instruments, even if no special ink direct current and backflow prevention mechanism is provided. We can provide something with a feeling. Further, there is known an ink which can be erased by rubber latex or an eraser having a shear thinning property.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a multiple writing instrument equipped with an eraser feeding device equipped with a plurality of mechanical pencils or at least one mechanical pencil having at least one mechanical pencil. Erasures that are suitable for each cursive type.

[0007]

The present invention has the following arrangement to achieve the above object. The compound writing instrument according to the first aspect of the present invention is provided with a plurality of mechanical pencils or a plurality of mechanical pencils each including at least one mechanical pencil in a shaft, and a tip of each mechanical pencil is set at an axis. In a double-type writing instrument that can selectively appear and disappear from the end opening, a plurality of erasers that can appear and disappear from the rear end of the shaft cylinder in conjunction with the slider are provided on the side surface of the shaft cylinder provided behind the shaft. It is characterized by. By preparing a special eraser suitable for the color type of the colored sharp core, the erasability can be almost satisfied.

According to a second aspect of the present invention, there is provided the double-type writing instrument according to the first aspect, wherein a plurality of locations are provided on the side surface of the shaft cylinder provided at the rear of the shaft. A leading slit is drilled, and an eraser holder integrally provided with the slider that protrudes through the slit is provided in an independent state, and an independent eraser is fixed to each eraser holder, and the selected slider is removed. The rear end of the eraser fixed to the eraser holder is provided so as to be able to protrude and retract from the rear end of the barrel by sliding in the front-rear direction along the slit.

According to a third aspect of the present invention, there is provided the double-type writing instrument according to the first aspect, wherein the front end of the front shaft and the front end of the center shaft are fixed to each other so as not to rotate and are prevented from coming off. In a plurality of guide grooves of the guide part provided, a writing body with a sliding piece fixed to the rear end, a return spring is laid between the front end of the guide part and the front end of the sliding piece, and attached backward to the center shaft. The cam slope is fitted so that it can be moved back and forth in the axial direction. By rotating the cylindrical cam with respect to the front shaft or the middle shaft, the sliding pieces are alternately slid in the front-rear direction so that the tip of each writing body can be selectively protruded and retracted from the front shaft front end port. A shaft cylinder is provided integrally extending behind the cylindrical cam. Is, it is possible to feed the core of the cylindrical cam and the shaft changes during the mechanical pencil selection.

According to a fourth aspect of the present invention, there is provided the double-type writing instrument according to the second aspect, wherein the narrow vertical groove along the slit and the slightly wide horizontal groove are substantially perpendicular to the vertical groove. Are provided at appropriate intervals, and the eraser holder is integrally provided with a slider on a side surface of a piece provided at the front end with a rib as a support shaft, and a locking projection is formed appropriately rearward of the piece, By sliding the slider in the front-rear direction along the slit, the locking projection can be engaged with and disengaged from the lateral groove of the slit.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the double writing instrument according to the present invention is characterized in that an eraser feeding device is integrally connected to a rear portion of the writing mechanism. First, the embodiment shown in FIG.
1 shows a double-type writing implement equipped with various kinds of writing bodies, a central shaft 1 having a guide portion 2 integrally, a leading shaft 3, an eraser feeding device 4 integrally having a cylindrical cam 5, and a pair of sliding pieces 6.
a and 6b, a mechanical pencil 7 and a ballpoint pen 8 are the main components.

The center shaft 1 is made of resin, and is provided with a guide portion 2a having an axially long guide groove 2a opened to the side surface from a substantially central portion to a rear end and a similar guide groove 2b on the opposite side surface. I have. The guide portion has two guide grooves formed in the cylindrical portion rising in the inner hole of the central shaft, and ribs formed in the inner hole wall of the central shaft so that a sliding piece described later is guided in the axial direction. Provided. In the front half of the guide portion 2, there is provided a tubular portion 9 having a partition portion 15 having holes 15a, 15b in communication with the guide grooves 2a, 2b and having an open front end. The stepped portion 31 has a bulged engagement portion 10 formed on a front outer peripheral portion thereof.

As shown in FIG. 2, a vertical groove 17 is formed on the rear side surface of the center shaft 1 through a narrow surface 17a through a forward inclined surface 17a.
Are connected to the circumferential groove 18 to form a substantially inverted T-shaped window. As will be described later, the protrusion 16 of the cylindrical cam 5 is
The projection 16 elastically expands the inclined surface 17a, passes through the narrow portion 17b, and enters the circumferential groove 18. The cylindrical cam 5 rotates within a range in which the protrusion 16 abuts on both circumferential walls of the circumferential groove 18, and the writing portion of the writing body 8 such as a mechanical pencil 7 or a ballpoint pen alternately protrudes and retracts from the front end of the front shaft. become. In addition, the circumferential groove 18 is made of the mechanical pencil 7
A wide knock groove 19 is provided so that the cylindrical cam 5 can be axially shifted at the position of the projection 16 when the writing element projects, and the position of the projection 16 when the writing object is stored or when the writing object 8 such as a ball-point pen projects. A narrow groove 18c is provided between the rear wall 18b and the front wall 18a of the circumferential groove 18 so that the cylindrical cam 5 cannot move substantially in the axial direction. Various means not limited to the above are already disclosed as means for retaining the cylindrical cam so as to be rotatable with respect to the center shaft so as to be rotatable within a certain range.

The tip shaft 3 is tapered at the front, has an inner step 27 at the tip of the inner hole, and is provided with a tip opening. In the rear end hole, an engagement groove 12 is provided, which engages with an engagement portion 10 provided on the outer peripheral portion of the cylindrical portion 9 of the guide cylinder so as to prevent the cylindrical portion 9 from slipping out and being prevented from rotating. . In addition, the cylindrical portion 9 and the front shaft 3
Is detachably fixed by an appropriate force.

The eraser feeding device 4 includes a shaft cylinder 4a, eraser holders 37 and 38 of the same shape, and a slider 4 of the same shape.
0, 41 and erasers 42a, 42b of the same shape. The shaft cylinder 4a is made of resin and integrally has a cylindrical cam 5 at the tip. The cylindrical cam 5 has a cylindrical shape, and has a cam slope 13 that is displaced circumferentially back and forth at a front end edge, and a notch 14 is formed at the foremost end of the cam slope 13.
Also, the cylindrical cam 5 is inserted into the longitudinal groove 18 of the center shaft 1 and elastically fitted into the circumferential groove 18 to a predetermined range (approximately 180).
The projection 16 is formed to rotate and prevent the slide from coming off at (degree).

Incidentally, a cylindrical cam 5 is provided at the front end of the shaft cylinder 4a.
Are formed, and slits 32 are provided in the axial direction at two opposing positions on the side surface of the shaft cylinder 4a. The slit 32 is a narrow vertical groove 3 pierced to the rear end in the longitudinal direction.
A slightly wide horizontal groove 34 substantially perpendicular to the vertical groove 3 and its vertical groove 33 is provided at appropriate intervals.

The eraser holder 37 (see FIGS. 3 and 4) has a groove 37c opened at the front end on the side surface of the front end piece 39, and a locking step 37d formed at the rear end of the groove. On the other hand, the plate-shaped slider 40 is provided with a rib 40a standing upright on the lower end at the rear end, and the engaging portion 40c of the rib 40a is connected to the locking step portion 3.
7d utilizing elastic displacement, and the slider 40 is integrally formed on the rear side surface of the piece 39 with the rib 40a as a support shaft.
Are fixed parallel to the rear of the eraser holder 37 in parallel. A locking projection 39a is formed on the piece 39 at an appropriate position behind the rib 40a. Also, shaft cylinder 4
a, when the slider 40 is pressed inward,
9a is displaced inward. Also, a rib 37 is provided at the rear end of the one part 39.
A fastening portion 37a surrounded by b is provided, and the eraser 42a is fixed to the fastening portion 37a.

As described above, the eraser holders 37 and 38 are inserted from the rear end of the shaft cylinder 4a, the ribs 40a of the sliders 40 and 41 are inserted into the vertical groove 33 of the slit 32 from the outside, and the locking projection 39a is inserted into the slit. By sliding the sliders 40 and 41 provided through the slit 32 in the front-rear direction along the slit 32, the slider 40, 41 provided in the slit 32 can be elastically engaged and disengaged. Eraser holder 37,3 provided in
By moving back and forth the rear end of the eraser, the rear end of the eraser fixed to the eraser holder can be protruded from the rear end of the barrel.

In order for the slider 40 to slide smoothly, the width of the rib 40a in the axial direction needs to be larger than the width of the lateral groove 34 to prevent the rib from engaging with the lateral groove. However, when the rib 40a is small due to design reasons, it can be solved by providing a detent between the inner surface of the shaft cylinder and the outer periphery of the cylinder of the eraser holder. 5 and 6
Shows another embodiment of the slider in which the rib 43a is provided between the rib 40a and the locking projection 43, and this may be used.

On the other hand, the sliding piece 6a has a projection 22a on the outer surface, a central portion protruding from the rear end surface of the projection 22a, and both sides thereof have a cam slope having substantially the same slope as the cam slope 13 of the cylindrical cam 5 described above. have. Further, a hole is provided which abuts against the flange portion 24 of the core pipe 23 to protrude and fit the rear of the core pipe 23 long. The sliding piece 6b has a projection 22b and a cam slope like the sliding piece 6a, and has a locking portion 26 at its tip for fastening the rear end of the writing body 8 such as a ball-point pen. Incidentally, the locking portion may be formed in a pipe shape and the rear end of the writing body may be fitted.

The mechanical pencil 7 has a built-in general chuck mechanism, and is joined to the core pipe 23 via a joint 29 connected to the chuck mechanism at the rear end.
The sliding piece 6a comes into contact with the flange portion 24 provided behind the
Is fitted, and the rear end hole of the core pipe 23 protruding from the rear end of the sliding piece 6a is closed by a tail plug 25 or the like. The leading of the lead is performed by moving the chuck according to the axial movement of the sliding piece 6a in a state where the step 28 at the tip of the mechanical pencil 7 is in contact with the inner step 27 of the front shaft 3.

Next, a description will be given in assembling order. The mechanical pencil 7 and the ball-point pen 8 have their sliding ends 6a and 6b connected to their rear ends, respectively, so that the guide grooves of the guide portion 2 of the center shaft described above are connected. 2a, 2b movably fitted,
A return spring 3 interposed between the front end surfaces of the sliding pieces 6a, 6b and the partition 15 on the front surfaces of the guide grooves 2a, 2b.
It is urged rearward by 0a, 30b. The eraser feeding device 4 inserts the cylindrical cam 5 into the rear end hole of the center shaft 1 to elastically fit the projection 16 into the circumferential groove 18, and is rotatable about 180 degrees in the circumferential direction with respect to the center shaft 1 and It stops and comes off. Further, the eraser feeding device 4 can shift the axis necessary for the center feeding with respect to the center shaft 1 in a state where the mechanical pencil 7 protrudes, so that the writing material 8 such as a ballpoint pen can be moved when the writing material is stored or the ballpoint pen is protruded. In this state, the axis transition is disabled. Since the sliding pieces 6a and 6b are always urged rearward by the return springs 30a and 30b, the cam slopes of the projections 22a and 22b are always kept in contact with the cam slope 13 of the cylindrical cam 5.

The engaging portion 10 of the cylindrical portion 9 is elastically fitted in the engaging groove 12 of the front shaft 3 with the rear end surface of the front shaft 3 in contact with the front surface of the step portion 31 of the center shaft 1. Thus, the front shaft 3 and the center shaft 1 are fixed in a state where rotation is prevented and the shaft is prevented from coming off. The tip shaft 3 is detachable with an appropriate force. In this state, when the shaft cylinder 4a is rotated to one side with respect to the front shaft 3 or the center shaft 1, the sliding piece 6a is rotated.
Is notched 1 at the forefront end of the cam slope 13 of the cylindrical cam 5
4 is engaged with the projection 22a of the sliding piece 6a of the one mechanical pencil 7 so that the writing tip projects from the tip end of the front shaft. When the barrel 4a is rotated in the other direction with respect to the front shaft 3 or the center shaft 1, the sliding piece 6a is retracted, the writing tip of the mechanical pencil 7 penetrates from the tip of the front shaft, and the sliding piece is moved. 6b moves forward, and the writing tip of the other ballpoint pen writing body 8 projects from the tip of the front shaft.

On the other hand, the eraser feeding device 4 includes a shaft cylinder 4
a. Insert the eraser holders 37 and 38 from the rear end of
The sliders 40, 41 are attached to the eraser holders 37, 38, and the locking projections 39a are elastically engaged with the lateral grooves 34 of the slits 32 provided in the shaft cylinder.
The eraser holders 37 and 38 are slidable with respect to the shaft cylinder via 41. Erasers 42a, 42b
Is inserted through the opening 36 at the rear end of the barrel, and the front end of each eraser is fixed to the fastening portion of the eraser holder.

FIG. 9 shows a cross section taken along line BB of FIG. As shown in the figure, a rib-shaped guide projection 4b is provided on the inner surface of the shaft cylinder 4a along the axial direction, so that the eraser and one of the eraser holders can move back and forth by themselves. There is no rattling problem.

FIG. 10 shows a state corresponding to FIG. 9 when three or more types of cursives are mounted. The basic structure is the same as in FIG.

[0027]

When the shaft cylinder 4a is rotated in one direction with respect to the front shaft 3 or the center shaft 1, the cam slope 13 of the cylindrical cam 5 is rotated as shown in FIG.
The notch 14 provided at the front end of the pen is engaged with the sliding piece 6a of one of the mechanical pencils 7 to protrude the writing end from the front end of the front shaft. At this time, the projection 16 of the cylindrical cam 5 is located at the knock groove 19 in the circumferential groove 18 of the center shaft 1. In this state, when the rear end of the barrel is knocked and the cylindrical cam 5 is shifted,
The operation is transmitted to the sliding piece 6 a, the core pipe 23, and the mechanical pencil 7, and the chuck together with the joint 29 shifts the shaft along with the joint 29 from the state where the step 28 of the writing tip abuts the inner step 27 of the front shaft 3. Then the core is paid out. When the barrel 4a is rotated to the other end with respect to the front shaft 3 or the center shaft 1, the mechanical pencil writing body 7 is retracted, and the writing tip of the ballpoint pen writing body 8 protrudes from the tip end of the front shaft instead.

Next, when the slider 40 is retracted with respect to the barrel 4a, the locking projection 39a is
4, the eraser holder 37 is gradually retracted, and the eraser 42a is fed out from the opening 36 at the rear end of the barrel. Also, the slider 40
Is pushed forward, the eraser holder 37 advances, and the eraser 42a enters through the opening 36. The slider 41 operates in the same manner.

By the way, a colored sharp core obtained by impregnating a porous fired core body with a dye or pigment ink can easily erase a writing line with an eraser, but the erasability is not sufficient depending on the color. There is something. Further, the eraser has the same color as the colored sharp core, and there is an advantage that the eraser and the stain on the paper surface are not conspicuous by using only the combination thereof. Therefore, the eraser can be almost satisfied by preparing a special eraser adapted to the color type of the colored sharp core. Similarly, some inks that can be erased with rubber latex or an eraser with shear thinning properties may not have sufficient erasability depending on the color. The erasure can be almost satisfied.

[0030]

As described above, the present invention relates to a multiple writing instrument with an eraser feeding device equipped with a plurality of mechanical pencils or a plurality of mechanical pencils having at least one mechanical pencil. By having a dedicated eraser, it is possible to satisfy the erasability suitable for the color type of the sharp core and the ink type of the ballpoint pen.

[Brief description of the drawings]

FIG. 1 is a longitudinal cross-sectional view of a main part of an entire writing instrument showing an embodiment of the present invention.

FIG. 2 is a diagram showing a joining relationship between a cylindrical cam and a center shaft.

FIG. 3 is a main part diagram showing a locking structure between a slider and an eraser holder.

FIG. 4 is a view of a main part corresponding to FIG. 3;

FIG. 5 is a view of a main part showing another locking structure of the slider and the eraser holder.

FIG. 6 is a diagram of a main part corresponding to FIG. 5; (A-A sectional view)

FIG. 7 is a top view showing an external appearance of a main part behind the barrel.

FIG. 8 is a front view showing an external appearance of a main part behind the barrel.

FIG. 9 is a sectional view taken along the line BB of FIG. 1;

FIG. 10 is a cross-sectional view showing a state corresponding to FIG. 9 when three or more types of cursives are mounted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Middle shaft 2 Guide part 2a Guide groove 2b Guide groove 3 Front shaft 4 Eraser feeding device 4a Shaft tube 4b Guide protrusion 5 Cylindrical cam 6a Sliding piece 6b Sliding piece 7 Mechanical writing body such as a mechanical pencil 8 Writing body such as ballpoint pen 9 Cylindrical part 10 Engaging part 11 Knock spring 12 Engaging groove 13 Cam slope 14 Notch 15 Partition part 15a Hole 15b Hole 16 Projection 17 Vertical groove 17a Inclined surface 18 Peripheral groove 18a Front wall 18b Back wall 18c Narrow groove 19 Knock groove 20 Wall 21 Window 22a Projection 22b Projection 23 Core pipe 24 Flange 25 Tail plug 26 Locking part 27 Inner step 28 Step 29 Joint 30a Return spring 30b Return spring 31 Step 32 Slit 33 Vertical groove 34 Horizontal groove 35 Locking step 36 Opening Part 37 eraser holder 37a fastening part 37b rib 37 Groove 37d Locking step 38 Eraser holder 39 One piece 39a Locking protrusion 40 Slider 40a Rib 40b Projection 40c Engaging portion 41 Slider 42a Eraser 42b Eraser 43 Locking protrusion 43a Rib 44 Clip 45 Shaft tube 45a Guide protrusion 46a Eraser Holder 46b Eraser holder 46c Eraser holder 47a Eraser 47b Eraser 47c Eraser

Claims (4)

[Claims] 1. A plurality of mechanical pencils or a plurality of mechanical pencils each including at least one mechanical pencil is mounted on a shaft, and the tip of each mechanical body can be selectively protruded and retracted from a shaft tip opening. The double writing implement according to claim 1, wherein a plurality of erasers are provided on a side surface of the shaft cylinder provided at the rear of the shaft so as to be able to protrude and retract from a rear end of the shaft cylinder in conjunction with a slider. 2. A side surface of a shaft cylinder provided behind the shaft,
A slit is drilled at the rear end in the longitudinal direction at multiple places,
The eraser holder provided integrally with the slider that protruded into the slit is provided in an independent state, the independent eraser is fixed to each eraser holder, and the selected slider is moved in the front and rear direction along the slit The rear end of the eraser fixed to the eraser holder is provided so as to be able to protrude and retract from the rear end of the barrel by sliding.
The double-type writing instrument according to item 1. 3. A writing instrument in which a front end of a front shaft and a front end of a center shaft are fixed to each other so as not to rotate and are prevented from coming off, and sliding pieces are fixed to a plurality of guide grooves of a guide portion provided integrally with the center shaft at a rear end. A return spring is laid between the front end of the guide section and the front end of the sliding piece, and the body is urged rearward against the center shaft and fitted so that it can move back and forth in the axial direction, and a cam slope is provided at the front end. The cylindrical cams are locked to the back with respect to the central shaft, and each sliding piece is brought into contact with the cam slope of the cylindrical cam. In the direction, the tip of each writing body can be selectively made to protrude and retract from the tip end of the tip shaft, and a shaft cylinder is provided integrally extending behind the cylindrical cam, and when a mechanical pencil is selected, The core can be extended by changing the axis of the cylindrical cam. The double-type writing instrument according to claim 1. 4. A narrow vertical groove along the slit and a slightly wide horizontal groove substantially orthogonal to the vertical groove are provided at appropriate intervals, and the eraser holder is provided with ribs on one side provided at the front end. A slider is integrally provided with the support shaft as a support shaft, and a locking projection is formed at an appropriate rear portion of the one part, and the locking projection is engaged with the lateral groove of the slit by sliding the slider in the front-rear direction along the slit. 3. The dual writing implement according to claim 2, wherein the writing implement is removable.