JP2015136930A - Component for writing instrument and writing instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a component for a writing instrument which is formed by a two way punching mold and secures sufficient attachment strength of a closing member to a barrel member, and to provide the writing instrument including the component for the writing instrument.SOLUTION: The invention provides the component for the writing instrument including: a barrel member 7 where an axial end part is opened; and a closing member 9a which is inserted into the end part and at least partially closes the end part, the closing member 9a where a fitting surface 94a fitted in the barrel member 7 includes a low part 941a having a relatively low height and a high part 942a having a relatively high height and the high part 942a is positioned closer to the insertion side than the lower part 941a.

Description

  The present invention relates to a writing instrument component including a shaft tube member and a closing member. Furthermore, this invention relates to the writing instrument provided with the component for writing instruments.

  2. Description of the Related Art Conventionally, writing instruments including a shaft cylinder member such as a cap and a shaft cylinder are known. Such a writing instrument is, for example, a ballpoint pen or a marking pen. In order to mainly decorate the writing instrument, a closing member that closes the end of the shaft tube member such as a crown and a tail plug is often attached to the end of the shaft tube member.

  However, since the occlusion member is small in size, it may be accidentally swallowed by children or animals. Therefore, it is necessary to increase the mounting strength of the closing member so that the closing member is not easily removed from the shaft member.

  Therefore, conventionally, as disclosed in Patent Document 1, a hemispherical recess formed on the fitting surface of the cap (medium cap) and a hemispherical shape formed on the fitting surface of the crown (head crown). A technique for increasing the mounting strength of the crown by fitting the convex portion is known. Further, in the techniques disclosed in Patent Document 2 and Patent Document 3, the mounting strength is increased by press-fitting the fitting surface of the smooth crown to the fitting surface of the smooth cap.

Utility Model Registration No. 2537893 Utility Model Registration No. 2560138 Utility Model Registration No. 2560140

  However, in the technique disclosed in Patent Document 1, when the cap recess and the crown projection formed on the fitting surface are formed by injection molding, they are often undercut. Undercut means a convex or concave portion that is caught on a mold when the molded product is taken out of the mold.

  When the undercut is formed by a simple two-way punching die, the molded product is taken out from the die by so-called “force punching”. At this time, the undercut may be deformed by contact with the mold, and a desired shape may not be obtained. This leads to a reduction in mounting strength. Moreover, in order to enable unreasonable removal, the shape, material and position of the undercut are limited. This also prevents the mounting strength from being increased.

  In addition, as in the techniques disclosed in Patent Documents 2 and 3, it is difficult to ensure sufficient mounting strength by press-fitting the fitting surface of the smooth crown to the fitting surface of the smooth cap. .

  Therefore, the present invention has been made in view of the above-described problems, and is a writing instrument component that is formed by a two-way punching die and that can ensure sufficient attachment strength of a closing member to a shaft tube member. An object of the present invention is to provide a writing instrument provided with the writing instrument part.

  In the first aspect of the present invention, a shaft tube member having an open end in the axial direction, and a closing member that is inserted into the end portion and at least partially closes the end, the fitting with the shaft tube member For a writing instrument, wherein the mating surface includes a low portion having a relatively low height and a high portion having a relatively high height, and the high portion is positioned closer to the insertion side than the low portion. Parts are provided.

  In the first aspect of the present invention, the boundary surface between the low part and the high part is perpendicular to the fitting surface, and the parting line of the closing member is formed along the boundary line between the low part and the high part. preferable.

  In the first aspect of the present invention, it is preferable that the parting line extends in a direction perpendicular to the axis of the shaft member and an oblique direction.

  In the first aspect of the present invention, it is preferable that the fitting surface of the shaft tube member with the closing member is smooth.

  In the first aspect of the present invention, it is preferable that the shaft tube member is a cap body and the closing member is a crown.

  In the 2nd aspect of this invention, the writing instrument provided with the writing instrument supplies of the 1st aspect of this invention is provided.

  According to the present invention, there are provided a writing instrument part that is formed by a two-way punching die and that can secure sufficient attachment strength of the closing member to the shaft tube member, and a writing instrument that includes the writing instrument part. .

1A to 1C are a front view, a right side view, and a front sectional view taken along line AA of FIG. 1B, respectively, of the writing instrument according to the embodiment of the present invention. FIG. 2 is a front sectional view of the cap assembly taken along line AA in FIG. FIG. 3 is a perspective view of the cap body. 4A to 4C are a front cross-sectional view, a plan view, and a bottom view of the cap body taken along line AA in FIG. 1B, respectively. FIG. 5 is a perspective view of the clip. 6A to 6D are a front view, a plan view, a right side cross-sectional view and a perspective view, respectively, taken along line DD of FIG. 6A. FIGS. 7A and 7B are a plan sectional view of the cap assembly along the line BB in FIG. 2, and a plan sectional view of the cap assembly along the line CC in FIG. It is. FIGS. 8A and 8B are a front view and a plan view of a crown of another embodiment, respectively. FIGS. 9A and 9B are a front view and a bottom view, respectively, of a tail plug according to another embodiment.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that these embodiments do not limit the present invention. In addition, constituent elements of the above embodiment include those that can be easily replaced by those skilled in the art and those that are substantially the same. Furthermore, various forms included in the above embodiment can be implemented in any combination.

  Initially, with reference to FIG. 1, the structure of the writing instrument which concerns on embodiment of this invention is demonstrated easily.

  1A to 1C are a front view, a right side view, and a front sectional view taken along line AA of FIG. 1B, respectively, of the writing instrument 1 according to the embodiment of the present invention. In this embodiment, the writing instrument 1 is a ballpoint pen. The writing instrument 1 may be another writing instrument such as a marking pen or a sign pen.

  The writing instrument 1 includes a writing instrument body 2 and a cap assembly 3 attached to the writing instrument body 2 so as to cover the front end portion of the writing instrument body 2. The cap assembly 3 can be detached from the writing instrument body 2. In the present specification, the cap side of the writing instrument is defined as the “front” side of the writing instrument, and the side opposite to the cap along the axial direction (longitudinal direction) of the writing instrument is defined as the “rear” side of the writing instrument.

  Hereinafter, the writing instrument body 2 will be described in detail with reference to FIG.

  The writing instrument body 2 includes a shaft cylinder 4, a refill 5 and a tail plug 6a. The shaft cylinder 4 has a substantially cylindrical shape, and the front end portion thereof has a tapered shape whose outer diameter gradually decreases. The shaft tube 4 is open at both ends (front end and rear end) in the axial direction. The shaft cylinder 4 is typically formed by resin injection molding. The fitting surface (the inner surface of the shaft tube 4) with the tail plug 6a of the shaft tube 4 is not formed with a convex or concave portion that becomes an undercut during molding. In other words, the fitting surface of the shaft tube 4 with the tail plug 6a is smooth.

  The refill 5 guides the ball pen tip 52 having the writing ball 51 at the front end, the joint 53 holding the ball pen tip 52, the ink occlusion body 54, and the ink occluded in the ink occlusion body 54 to the writing ball 51. And an ink guide core 55. The ink occlusion body 54 includes a synthetic fiber bundle that is impregnated with ink such as acrylic, polyester, polypropylene, or acetate. The ink occlusion body 54 is inserted into the shaft tube 4 from the rear end portion of the shaft tube 4, and the position thereof is fixed by the tail plug 6a. The ink guide core 55 is connected to the ballpoint pen tip 52, and the ink guide core 55, the ballpoint pen tip 52, and the joint 53 are attached to the front end portion of the shaft tube 4. At this time, since the ink guide core 55 is inserted into the front end portion of the ink occlusion body 54, ink can be guided.

  The tail plug 6 a is inserted into the rear end portion of the shaft tube 4 after the ink occlusion body 54 is inserted into the shaft tube 4 and closes the rear end portion of the shaft tube 4. The tail plug 6a has a substantially cylindrical shape. The insertion side of the tail plug 6a is open, and the exposed side of the tail plug 6a is closed. The tail plug 6 a includes an insertion portion 61 a that is inserted into the shaft tube 4 and an exposed portion 62 a that is exposed from the shaft tube 4. The outer diameter of the exposed portion 62 a is substantially equal to the outer diameter of the shaft tube 4, and is larger than the outer diameter of the insertion portion 61 a and the inner diameter of the shaft tube 4. For this reason, when the tail plug 6 a is inserted into the rear end portion of the shaft tube 4, the exposed portion 62 a comes into contact with the rear end of the shaft tube 4. Thus, the position of the tail plug 6a in the axial direction with respect to the shaft tube 4 is determined.

  Moreover, although not shown in figure, the convex engaging part is provided in the fitting surface 63a (outer surface of the insertion part 61a) with the axial cylinder 4 of the tail plug 6a. The fitting strength of the tail plug 6a with respect to the shaft tube 4 is increased by engaging the engaging portion of the tail plug 6a with the fitting surface of the shaft tube 4 (the inner surface of the shaft tube 4). The tail plug 6a is typically formed by resin injection molding. In this case, since the engaging portion is undercut, it is taken out from the mold by so-called “force removal”.

  In this case, since there is a possibility that sufficient attachment strength of the tail plug 6a to the shaft tube 4 may not be secured, in order to make it difficult to remove the tail plug 6a from the shaft tube 4 by hand, the shaft plug 4 of the tail plug 6a is removed from the shaft tube 4. The protruding amount in the axial direction (the dimension in the axial direction of the exposed portion 62a) is 3 mm or less, the protruding amount excluding the tapered portion is 1 mm or less, and the taper angle of the tapered portion with respect to the axis of the shaft cylinder 4 is 30 ° to 90 °. It is preferable that

  Hereinafter, the cap assembly 3 will be described in detail with reference to FIGS.

  FIG. 2 is a front sectional view of the cap assembly 3 taken along the line AA in FIG. The cap assembly 3 includes a cap body 7, a clip 8 attached to the cap body 7, and a crown 9a. The cap assembly 3 is attached to the writing instrument body 2 and covers the front end portion of the writing instrument body 2, thereby preventing unintended writing when not in use and reducing ink volatilization. The cap assembly 3 protects the front end portion of the writing body such as the ballpoint pen tip 52 of the ballpoint pen.

  FIG. 3 is a perspective view of the cap body 7. FIGS. 4A to 4C are a front sectional view, a plan view, and a bottom view of the cap body 7 along the line AA in FIG. 1B, respectively. The cap body 7 is a shaft cylinder member having a substantially cylindrical shape. The front end and the rear end of the cap body 7 are open.

  An inner cylinder 71 having a cylindrical shape is provided inside the cap body 7. The rear end portion of the inner cylinder 71 is open, and the front end portion of the inner cylinder 71 is closed. As shown in FIG. 1A, the inner cylinder 71 covers the ball-point pen tip 52 when the cap assembly 3 is attached to the writing instrument body 2.

  A plurality of convex engaging portions 72 are provided on the fitting surface of the cap body 7 with the shaft cylinder 4 (inner surface of the cap body 7). The engaging portions 72 are separated from each other in the circumferential direction. The engaging strength of the cap body 7 with respect to the shaft cylinder 4 is increased by the engagement portion 72 engaging with the fitting surface of the shaft cylinder 4 (the outer surface of the shaft cylinder 4).

  The cap body 7 is typically formed by resin injection molding. In this case, since the engaging portion 72 is undercut, it is taken out from the mold by so-called “force removal”. The engaging portion 72 has a rounded edge so that it can be easily removed from the mold, and the height of the convex portion is designed to be low. With such a shape, it is difficult to increase the mounting strength of the cap body 7 with respect to the shaft cylinder 4, but this is not particularly problematic because the cap body 7 is assumed to be detached from the shaft cylinder 4. . In addition, variations in mounting strength that may occur due to excessive removal are allowed.

  As shown in FIG. 3 and FIG. 4B, a clip insertion hole 73 for attaching the clip 8 to the cap body 7 and a crown 9 a for attaching the crown 9 a to the cap body 7 are provided at the front end of the cap body 7. A crown insertion hole 74 and two vent holes 75 for preventing suffocation when the cap is accidentally swallowed are formed. A first separation wall 76 is formed between the clip insertion hole 73 and the crown insertion hole 74. A second separation wall 77 is formed between the crown insertion hole 74 and each ventilation hole 75. The inner surface of the second separation wall 77 functions as a fitting surface 78 with the crown 9a. The fitting surface 78 is not formed with a convex or concave portion that is undercut at the time of molding. In other words, the fitting surface 78 is smooth.

  FIG. 5 is a perspective view of the clip 8. The clip 8 has a role of sandwiching paper or clothes between the clip 8 and the cap body 7. The clip 8 has an insertion portion 81 bent twice at a substantially right angle and an arc end portion 82 bent in an arc shape. When the clip 8 is attached to the cap body 7, the insertion portion 81 is press-fitted into the clip insertion hole 73 of the crown 9a. The insertion portion 81 has a protrusion 83 protruding in the width direction. Since the width of the protrusion 83 is larger than the width of the clip insertion hole 73, when the clip 8 is attached to the cap body 7, the tip of the protrusion 83 is strongly engaged with the inner surface of the clip insertion hole 73. For this reason, sufficient attachment strength of the clip 8 with respect to the cap main body 7 is securable.

  6A to 6D are a front view, a plan view, a right side cross-sectional view and a perspective view taken along line DD of FIG. 6A, respectively. The crown 9 a is inserted into the crown insertion hole 74 of the cap body 7 to close the ceiling crown insertion hole 74. In other words, the crown 9a partially closes the front end portion of the cap body 7. The crown 9a has a substantially rectangular parallelepiped shape, and the insertion side of the crown 9a is open. On the other hand, the exposed side of the crown 9a is closed, and an exposed surface 91a exposed from the cap body 7 is formed. The crown 9 a abuts against the front end portion of the inner cylinder 71 of the cap body 7, so that the position in the axial direction relative to the cap body 7 is determined. At this time, as can be seen from FIG. 2, the exposed surface 91a of the crown 9a and the front end surface of the cap body 7 are flush with each other. This enhances the design of the cap assembly 3. Note that the crown can have other shapes such as a cylinder and a pentagon. In this case, as a matter of course, the cap canopy insertion hole of the cap body has a shape complementary to the cap so that the cap can be inserted.

  The crown 9a has a protruding portion 92 that protrudes outward in the width direction at the end portion on the exposed side. FIGS. 7A and 7B are a plan sectional view of the cap assembly 3 along the line BB in FIG. 2 and a sectional plan view of the cap assembly 3 along the line CC in FIG. Figure. As can be seen from FIGS. 2 and 7A, the protrusion 92 covers the front end portion of the first separation wall 76 of the cap body 7 when the crown 9 a is attached to the cap body 7. For this reason, since the clearance gap between the clip 8 and the crown 9a when it sees from the front can be minimized, the design property of the cap assembly 3 is improved. Also, as shown in FIG. 6D, on the insertion side of the protrusion 92, there are two sliding portions 93 that slide on the inner surface of the first separation wall 76 when inserted into the crown insertion hole 74. Is formed.

  The crown 9 a has two fitting surfaces 94 a with the cap body 7. Each fitting surface 94a includes a low portion 941a having a relatively low height and a high portion 942a having a relatively high height. The high portion 942a is located closer to the insertion side than the low portion 941a. A dimension L1 between the two high portions 942a (see FIG. 6C) is larger than a dimension L2 between the two fitting surfaces 78 of the cap body 7 (see FIG. 4B). For this reason, the fitting surface 94a of the crown 9a is located at the position of FIG. 7 (b) where the cross section of the high portion 942a is cut rather than the position of FIG. 7 (a) where the cross section of the low portion 941a is cut. It strongly engages with the fitting surface 78 of the cap body 7. In addition, if the dimension L3 (refer FIG.6 (c)) between the two low parts 941a is smaller than the dimension L1, it will be small even if larger than the dimension L2 between the two fitting surfaces 78 of the cap main body 7. FIG. May be.

  In addition, the height of the low portion 941a and the height of the high portion 942a are constant, and the height of the fitting surface 94a increases stepwise from the exposed side toward the insertion side. In other words, the boundary surface between the low portion 941a and the high portion 942a is perpendicular to the fitting surface 94a. For this reason, when the crown 9a is attached to the cap main body 7, the boundary surface between the low portion 941a and the high portion 942a is strongly engaged with the fitting surface 78 of the cap main body 7. Sufficient mounting strength can be ensured. Moreover, in order to make it easy to insert the top crown 9a into the top crown insertion hole 74 of the cap body 7, the insertion end portion 95a of the top crown 9a may have a tapered shape whose outer diameter gradually decreases. .

  The crown 9a is typically formed by resin injection molding. In this case, a parting line (PL) indicating the position of the parting surface that is a mating surface of the mold is formed as a two-dot chain line shown in FIG. 6A, for example. That is, the parting surface is formed along the surface on the insertion side of the protruding portion 92 and the boundary surface between the low portion 941a and the high portion 942a. For this reason, the parting line is formed along the boundary line between the low portion 941a and the high portion 942a. A die (not shown) is a two-way die and opens in the direction of the arrow in FIG. Typically, the mold on the exposed side is the fixed side, and the mold on the insertion side is the movable side. When the movable mold moves after molding, the crown 9a is left behind in the movable mold, and is finally pushed out of the movable mold by the ejector pin and taken out from the mold. With this configuration, no undercut is formed during molding.

  In the present embodiment, the crown 9a has a protruding portion 92 that protrudes outward in the width direction at the end portion on the exposed side. Therefore, in order to form the protruding portion 92 with a two-way punching die, at least the parting surface It is necessary to form a part near the exposed surface 91a. In this case, when the parting surface is formed near the exposed surface over the entire crown, the boundary surface between the low part and the high part is also formed near the exposed surface. As a result, the region of the high portion is widened, and most of the fitting surface 78 of the cap body 7 is pushed outward in the radial direction, so that the fitting surface 78 of the crown and the cap body 7 is viewed from the front. A gap is easily formed between the two. This is not preferable from the viewpoint of design.

  This problem is solved by the following configuration of the present embodiment. In the present embodiment, the exposed-side surface of the high portion 942a extends along the insertion-side surface of the projecting portion 92 near the exposed surface 91a, and then obliquely extends from the exposed side toward the inserting side. However, it extends in parallel with the exposed surface 91a near the insertion end portion 95a. At this time, as shown in FIG. 6A, the parting line of the crown 9a is oblique to the direction perpendicular to the axis of the cap body 7 when the crown 9a is attached to the cap body 7. Extending in the direction and. The axis of the cap body 7 corresponds to the line DD in FIG. As a result, in the front view (FIG. 6A), the lateral width of the low portion 941a is reduced and the lateral width of the high portion 942a is increased from the exposed side toward the insertion side. This makes it possible to reduce the region of the high portion 942a close to the exposed surface 91a while forming a shape like the protruding portion 92 with the two-way punching die. Therefore, the clearance gap between the crown 9a and the fitting surface 78 of the cap main body 7 can be made small. Further, since a part of the parting line is formed obliquely with respect to the direction in which the mold opens, the movable mold can be easily separated from the fixed mold.

  Hereinafter, with reference to FIG.8 and FIG.9, the crown and tail plug of another embodiment are demonstrated. In the following description, the description will focus on parts that are different from the above embodiment.

  FIGS. 8A and 8B are a front view and a plan view, respectively, of a crown 9b according to another embodiment. The crown 9b has a substantially cylindrical shape, and the insertion side of the crown 9b is open. On the other hand, the exposed side of the crown 9b is closed to form an exposed surface 91b exposed from the cap body.

  The crown 9b has a fitting surface 94b with the cap body. The fitting surface 94b includes a low portion 941b having a relatively low height and a high portion 942b having a relatively high height. The high portion 942b is located closer to the insertion side than the low portion 941b. The outer diameter D1a of the high portion 942b is larger than the inner diameter of the crown crown insertion hole. For this reason, the high part 942a engages with the fitting surface of the cap body more strongly than the low part 941b. The outer diameter D2a of the low portion 941b may be larger or smaller than the inner diameter of the crown insertion hole as long as it is smaller than the outer diameter D1a.

  In addition, the height of the low portion 941b and the height of the high portion 942b are constant, and the height of the fitting surface 94b increases stepwise from the exposed side toward the insertion side. In other words, the boundary surface between the low portion 941b and the high portion 942b is perpendicular to the fitting surface 94b. Therefore, when the crown 9b is attached to the cap body, the boundary surface between the low portion 941b and the high portion 942b is strongly engaged with the fitting surface of the cap body. Can be secured. Further, in this embodiment, the crown insertion hole is formed to have a circular cross section.

  The crown 9b is typically formed by resin injection molding. In this case, the parting line (PL) is formed like a two-dot chain line shown in FIG. That is, the parting surface is formed along the boundary surface between the low portion 941b and the high portion 942b. Therefore, the parting line is formed along the boundary line between the low portion 941b and the high portion 942b. A die (not shown) is a two-way die and opens in the direction of the arrow in FIG. Typically, the mold on the exposed side is the fixed side, and the mold on the insertion side is the movable side. When the movable mold moves after molding, the crown 9b is left behind in the movable mold, and is finally pushed out of the movable mold by the ejector pin and removed from the mold. With this configuration, no undercut is formed during molding.

  In this embodiment, since the crown 9b does not have a shape protruding radially outward near the exposed surface, the position of the parting surface in the axial direction can be freely set. For example, as shown in FIG. 8A, it is preferable that the parting surface is formed on the insertion side with respect to half the axial dimension of the crown 9b. As a result, even if the fitting surface of the cap main body is pushed radially outward by the high portion 942b, the position is far from the exposed surface 91b, so that the cap crown 9b and the cap main body fit when viewed from the front. The gap between the mating surfaces can be reduced.

  Moreover, in this embodiment, the high part 942b is formed over the perimeter of the crown 9b. Thus, even if the dimension of the high portion 942b in the axial direction is short, the region of the high portion 942b can be enlarged, and sufficient mounting strength of the crown 9b to the cap body can be ensured. Further, in order to make it easy to insert the crown 9b into the crown insertion hole of the cap body, the insertion end portion 95b of the crown 9b gradually decreases in outer diameter as shown in FIG. It may have a tapered shape. Further, although not shown, a clip insertion hole and a vent hole may be formed on the exposed surface of the crown, instead of the front end portion of the cap body. The shape of the crown 9b can also be applied to the tail plug. In this case, since the tail plug does not have an exposed portion whose outer diameter is larger than the inner diameter of the shaft cylinder, the position in the axial direction with respect to the shaft cylinder is determined by the tail plug contacting the ink reservoir.

  FIGS. 9A and 9B are a front view and a bottom view of a tail plug 6b of another embodiment, respectively. The tail plug 6b has a substantially cylindrical shape. The insertion side of the tail plug 6b is open, and the exposed side of the tail plug 6b is closed. The tail plug 6b includes an insertion portion 61b inserted into the shaft tube and an exposed portion 62b exposed from the shaft tube. The exposed portion 62b has a large-diameter portion 621 that protrudes radially outward. The large diameter portion 621 is formed over a part of the entire circumference of the tail plug 6b. The outer diameter of the large diameter portion 621 is substantially equal to the outer diameter of the shaft tube, and is larger than the outer diameter of the insertion portion 61b and the inner diameter of the shaft tube. For this reason, when the tail plug 6b is inserted into the rear end portion of the shaft tube, the large-diameter portion 621 contacts the rear end of the shaft tube. As a result, the axial position of the tail plug 6b with respect to the shaft tube is determined.

  Further, the tail plug 6b has a fitting surface 63b with the shaft tube. The fitting surface 63b includes a low portion 631 having a relatively low height and a high portion 632 having a relatively high height. The high part 632 is located on the insertion side with respect to the low part 631. The outer diameter D1b of the high portion 632 is larger than the inner diameter of the shaft tube. For this reason, the high part 632 engages with the fitting surface of the shaft tube more strongly than the low part 631. The outer diameter D2b of the low portion 631 may be larger or smaller than the inner diameter of the shaft tube as long as it is smaller than D1b.

  Moreover, the height of the low part 631 and the height of the high part 632 are constant. For this reason, the height of the fitting surface 63b increases stepwise from the exposed side toward the insertion side at the circumferential position where the high portion 632 is formed. In other words, the boundary surface between the low portion 631 and the high portion 632 is perpendicular to the fitting surface 63b. For this reason, when the tail plug 6b is attached to the shaft tube, the boundary surface between the low portion 631 and the high portion 632 is strongly engaged with the fitting surface of the shaft tube, so that sufficient attachment strength of the tail plug 6b with respect to the shaft tube is sufficient. Can be secured.

  The tail plug 6b is typically formed by resin injection molding. In this case, the parting line (PL) is formed, for example, like a two-dot chain line shown in FIG. That is, the parting surface is formed along the insertion side surface of the large diameter portion 621 and the boundary surface between the low portion 631 and the high portion 632. Therefore, the parting line is formed along the boundary line between the low part 631 and the high part 632. A die (not shown) is a two-way die and opens in the direction of the arrow in FIG. Typically, the mold on the exposed side is the fixed side, and the mold on the insertion side is the movable side. When the movable mold moves after molding, the tail plug 6b is left behind in the movable mold, and is finally pushed out of the movable mold by the ejector pin and taken out from the mold. In this embodiment, as is clear from FIG. 9B, the high portion 632 is formed so as to be spaced apart from the large diameter portion 621 in the circumferential direction, and therefore does not undercut during molding. Therefore, in this configuration, no undercut is formed during molding. The shape of the tail plug 6b can also be applied to the crown.

DESCRIPTION OF SYMBOLS 1 Writing instrument 2 Writing instrument main body 3 Cap assembly 4 Shaft cylinder 5 Refill 51 Writing ball 52 Ball-point pen tip 53 Joint 54 Ink occlusion body 55 Ink guide core 6a, 6b Tail plug 61a, 61b Insertion part 62a, 62b Exposed part 621 Large diameter part 63a 63b Fitting surface 631 Low part 632 High part 7 Cap body 71 Inner cylinder 72 Engaging part 73 Clip insertion hole 74 Cap crown insertion hole 75 Vent hole 76 First separation wall 77 Second separation wall 78 Fitting surface 8 Clip 81 Insertion part 82 Arc end part 83 Projection 9a, 9b Crown crown 91a, 91b Exposed surface 92 Projection part 93 Sliding part 94a, 94b Fitting surface 941a, 941b Low part 942a, 942b High part 95a, 95b Insertion end L1 Dimension between two high parts L2 Dimension between two mating surfaces L3 Dimension between two low parts D1a, D1b Outer diameter of the upper part D2a, D2b Outer diameter of the lower part PL Parting line

Claims (6)

An axial tube member whose axial end is open,
A closing member that is inserted into the end portion and at least partially closes the end portion, and a fitting surface with the shaft tube member has a relatively low height and a relatively high height. A writing instrument part comprising: a high portion including a closing member, the high portion being positioned on an insertion side with respect to the low portion.   The boundary surface between the low portion and the high portion is perpendicular to the fitting surface, and the parting line of the blocking member is formed along the boundary line between the low portion and the high portion. Writing instrument parts as described in 1.   The writing instrument part according to claim 2, wherein the parting line extends in a direction perpendicular to and oblique to the axis of the axial tube member.   The writing instrument part according to any one of claims 1 to 3, wherein a fitting surface of the shaft tube member with the closing member is smooth.   The writing instrument part according to any one of claims 1 to 4, wherein the shaft cylinder member is a cap body, and the closing member is a crown.   A writing instrument comprising the writing instrument part according to any one of claims 1 to 5.

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