Writing instrument parts and method for manufacturing the same

Abstract

To prevent a material forming a part having no functional part from leaking to a functional portion in a writing instrument part composed of two parts made of different materials.SOLUTION: There is provided a writing instrument part composed of a covering portion, which is a part formed of synthetic resins of different materials, and an embedded portion partially covered by the covering portion. The functional portion, which is part of the embedded portion, protrudes from the supporting surface, which is part of the covering portion. A sealing surface, which is part of the embedded portion, is formed on the peripheral edge of the functional portion. The sealing surface forms a continuous surface with the supporting surface.SELECTED DRAWING: Figure 1G

Description

Technical Field

[0001] The present invention relates to a writing instrument part constituting a part of a writing instrument and a method for manufacturing the same.

Background Art

[0002] Patent Document 1 discloses a technique for forming a knock for core feeding, which is a member for feeding a desired pen core in a knock-type multicolor pen, by two-color molding. The knock for core feeding formed by this two-color molding has a two-layer structure of an outer colored transparent outer piece located on the outside and a white opaque inner piece located on the inside. That is, the knock for core feeding disclosed in Patent Document 1 is configured such that the entire outer surface is colored.

[0003] In addition, Patent Document 2 discloses a technique for forming, in a multicolor retractable writing instrument, a pusher that is operated when the writing part moves forward and backward as a separate part from a pusher main body and a color identification part having a color different from that of the pusher main body, and fitting the color identification part into the pusher main body. However, the color identification part is a minute part with respect to the pusher main body, and it is difficult to attach it by hand.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] When forming a synthetic resin part such as a knock rod used in a knock-type ballpoint pen by two-color molding, when a part of the primary molded product is configured as a part having some function in the writing instrument (for example, the cam mechanism in the knock rod) (hereinafter referred to as the "functional part"), there is a concern that the resin injected during the secondary molding leaks from the gap generated by the shrinkage of the primary molded product into the functional part, resulting in a change in the shape of the functional part and inhibiting the function.

[0006] Therefore, an embodiment of the present application aims to prevent the material forming the part without a functional part from leaking into the functional part in a writing instrument part composed of two parts of different materials.

Means for Solving the Problem

[0007] In view of the above problems, the writing instrument part according to the embodiment of the present application is composed of a covering part formed of synthetic resins of different materials from each other and an embedded part partially covered by the covering part, and a functional part, which is a part of the embedded part, protrudes from a support surface that is a part of the covering part, and a sealing surface that is a part of the embedded part is formed at the periphery of the functional part, and the sealing surface constitutes a continuous surface with the support surface.

[0008] Here, the materials forming the covering part and the embedded part are formed of synthetic resins of different materials from each other. Note that synthetic resins of different materials include not only cases where the resin types are different from each other (for example, polycarbonate and thermoplastic elastomer), but also those where the resin types are the same and only the colors are different (for example, ABS).

[0009] Note that the embedded part preferably has a flange part having the sealing surface, and the functional part preferably protrudes from the sealing surface.

[0010] In addition, the method for manufacturing a writing instrument part according to the embodiment of the present application is by two-color molding in which the embedded part among the writing instrument parts is formed by primary molding and the coating part is formed by secondary molding. The embedded part is formed by injection molding into a primary cavity formed by a movable mold and a primary molding mold. The edge of the movable mold at the parting surface of the primary cavity is surrounded by the edge of the primary molding mold at the parting surface, and the sealing surface is formed between the edge of the movable mold and the edge of the primary molding mold.

[0011] Note that it is desirable that the sealing surface be crimped to the movable mold at the parting surface between the movable mold and the secondary molding mold during the secondary molding.

[0012] In addition, the writing instrument part is a knock bar attached to the rear end of each of a plurality of refills in a writing instrument in which the plurality of refills are accommodated in a shaft cylinder. It is desirable that a convex curved surface protruding toward the axis is formed at the attachment portion to the rear end of the refill formed at the tip of the knock bar. Further, the convex portion preferably has a convex curved surface shape.

Advantages of the Invention

[0013] With the above configuration, the embodiment of the present application can prevent the material forming the part without a functional part from leaking into the functional part in a writing instrument part composed of two parts of different materials.

[0014] Also, when the writing instrument part is a knock bar attached to the rear end of each of a plurality of refills in a writing instrument in which the plurality of refills are accommodated in a shaft cylinder, a convex curved surface is formed at the attachment portion to the rear end of the refill formed at the tip of this knock bar, so that by directing the bottom surface side of the refill in the outer peripheral direction, it is possible to prevent a feeding failure of the refill.

Brief Description of the Drawings

[0015]

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MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, an embodiment of the present application will be described with reference to the drawings. The reference numerals commonly used in the drawings indicate corresponding parts even if not specifically mentioned in the description of each drawing. In the drawings described below, the tip side of the writing instrument 100 shown in FIG. 17A is referred to as the "bottom surface", the rear end side as the "flat surface", the outer surface side as the "front surface", and the inner surface side as the "back surface". In addition, the right side as viewed from the "front surface" is referred to as the "right side surface".

[0017] (1) First embodiment A writing instrument part 10 of a first embodiment of the present application is configured as a knock bar 11, as shown in FIG. 1A, a front outer perspective view, FIG. 1B, a front view, FIG. 1C, a right side view, FIG. 1D, a bottom view, FIG. 1E, a plan view, FIG. 1F, and FIG. 1G, which is a cross-sectional view II of FIG. 1A.

[0018] This knock bar 11 is generally rod-shaped, and its longitudinal direction coincides with the longitudinal direction of a window hole 131 (see Figs. 17A, 17B, 18A, and 18B) of the writing instrument 100 described below. When attached to the writing instrument 100, the knock bar 11 has an outer part 40 located on the outside, and an inner part 41 located on the inside. That is, the knock bar 11 has a structure in which the inner part 41, which is narrower than the outer part 40, protrudes from a support surface 22 (Figs. 1C, 1D, 1E, and 1F) that constitutes the inner side of the outer part 40. This support surface 22 is formed as an inner step 42, which is a step between the outer part 40 and the inner part 41.

[0019] The rear end side of the knock bar 11 is formed as a knock projection 43 protruding outward. In the front half portion of the outer portion 40, wing-like portions 45 protruding longitudinally on both sides are formed, and the width is wider than that of the rear half portion. The rear end of the wing-like portion 45 is a rear step 46. On the other hand, the tip of the knock bar 11 is a spring externally inserted portion 48 with a reduced width and height via a front step 47. Further, the tip of the spring externally inserted portion 48 is a refill mounting portion 49 with a reduced width and height. On the outer periphery of the spring externally inserted portion 48, a spring 150 (see FIGS. 17B and 18B), which will be described later, is externally inserted, and the rear end of the externally inserted spring 150 abuts against the front step 47. The refill mounting portion 49 is inserted into the rear end of a refill 200 (see FIGS. 17B and 18B), which will be described later.

[0020] As shown in FIG. 1G, the knock bar 11 is composed of parts of an embedded portion 30 as a primary molded body and a covering portion 20 as a secondary molded body by two-color molding. The covering portion 20 and the embedded portion 30 are formed of different materials, specifically synthetic resins of different colors. A part of the embedded portion 30 is covered by the accommodating portion 21 of the covering portion 20. A display portion 35, which is a part of the embedded portion 30, is exposed from a display groove 44, which is a groove formed in the knock projection 43 (FIGS. 1A, 1B, 1D, 1E, and 1F).

[0021] On the inner surface side of the rear end side of the knock bar 11, an inner portion 41 protrudes from a support surface 22 (inner step 42). Among this inner portion 41, a locking projection 50 as a functional portion 33 of the embedded portion 30 is formed near the rear end. Further, in front of this locking projection 50, a release projection 51 formed as a part of the covering portion 20 is formed. Further, in front of this release projection 51, two recessed portions 52 are formed.

[0022] The embedded part 30 constituting the knock bar 11 of this embodiment is shown in a front outer perspective view (FIG. 2A), a rear inner perspective view (FIG. 2B), a front view (FIG. 2C), a rear view (FIG. 2D), a right side view (FIG. 2E), a bottom view (FIG. 2F), a plan view (FIG. 2G), and a cross-sectional view taken along line II-II of FIG. 2C and FIG. 2D (FIG. 2H). The embedded part 30 is composed of a platform-shaped flange part 31 that spreads inward, a protruding part 34 that protrudes outward from the flange part 31, a seal surface 32 that is the inner surface of the flange part 31, and a functional part 33 that protrudes inward from the seal surface 32 and serves as an inner part 41 whose periphery is surrounded by the seal surface 32. The functional part 33 functions as a locking protrusion 50 of the knock bar 11 (see FIG. 1A, FIG. 1D to FIG. 1G). The flange portion 31 and the protruding portion 34 are portions that are accommodated in the accommodation portion 21 (see FIG. 1G) of the covering portion 20. The outer edge of the protruding portion 34 serves as an indication portion 35 that is exposed from an indication groove 44 (see FIGS. 1A and 1B) of the knock bar 11.

[0023] On the other hand, on the inner surface side of the flange portion 31, the peripheral portion surrounding the inside portion 41 serves as a sealing surface 32 (see Figs. 2B and 2D). This sealing surface 32 constitutes a continuous surface with the support surface 22 of the knock bar 11, as shown in Figs. 1C and 1G.

[0024] The cover 20 constituting the knock bar 11 of this embodiment is shown in a front view (FIG. 3A), a back view (FIG. 3B), a right side view (FIG. 3C), and a cross-sectional view (FIG. 3D) taken along line III-III of FIGS. 3A and 3B. The cover 20 is generally rod-shaped, and its longitudinal direction coincides with the longitudinal direction of a window hole 131 (see FIGS. 17A, 17B, 18A, and 18B) of the writing instrument 100 described below. The cover 20 has an outer part 40 located on the outside when attached to the writing instrument 100, and an inner part 41 located on the inside. That is, the cover 20 has a structure in which the inner part 41, which is narrower than the outer part 40, protrudes from a support surface 22 (FIG. 3B) constituting the inner side of the outer part 40. This support surface 22 is formed as an inner step 42, which is a step between the outer part 40 and the inner part 41. The rear end side of the covering portion 20 is formed as an outwardly protruding knock protrusion 43. An indication groove 44 is formed on the outer surface of the knock protrusion 43.

[0025] In the front half of the outer portion 40, wing-shaped portions 45 protruding longitudinally on both sides are formed, and it is wider than the rear half. The rear end of the wing-shaped portion 45 forms a rear step 46. On the other hand, the tip of the covering portion 20 forms a spring insertion portion 48 with reduced width and height via a front step 47. Further, the tip of the spring insertion portion 48 forms a refill mounting portion 49 with reduced width and height.

[0026] On the other hand, an inner portion 41 protrudes from the support surface 22 (inner step 42) on the inner surface side of the covering portion 20. Among this inner portion 41, a release protrusion 51 is formed near the rear end. Further, two recessed portions 52 are formed in front of this release protrusion 51. Also, on the rear end side of the covering portion 20, a housing portion 21 for housing the flange portion 31 and the protruding portion 34 of the embedded portion 30 is formed.

[0027] The knock bar 11 of this embodiment is formed by two-color molding of two types of synthetic resin. Specifically, the embedded portion 30 is formed by primary molding, and the covering portion 20 is formed by secondary molding. As a result, the flange portion 31 and the protruding portion 34 of the embedded portion 30 are in a state of being embedded in the housing portion 21 of the covering portion 20 (see FIG. 1G). The manufacturing method of this knock bar 11 will be described with reference to FIGS. 4A to 4C and FIGS. 5A and 5B.

[0028] FIG. 4A is a cross-sectional view showing a mold before primary molding, showing a state in which the movable mold 500 and the primary molding mold 600 are joined. In the movable mold 500, a cavity corresponding to the inner portion 41 of the knock bar 11 is formed, and in this cavity, a primary gate 515 through which primary molding resin is injected from the primary runner 510 and a secondary gate 525 through which secondary molding resin is injected from the secondary runner 520 are open. On the other hand, in the primary molding mold 600, a cavity corresponding to the flange portion 31 and the protruding portion 34 of the embedded portion 30 is formed, and a primary cavity 610 is formed by this cavity and a part of the cavity of the movable mold 500 type. In this state, as shown in the enlarged view of FIG. 4B, an edge Q of the movable mold 500 on the split surface P1 of the primary cavity 610 is surrounded by an edge R of the primary molding mold 600 on this split surface P1.

[0029] Fig. 4C shows the state in which the primary molded resin is injected into the primary cavity 610 shown in Fig. 4A through the primary gate 515 from the primary runner 510. In this state, the primary cavity 610 is filled with the primary molded resin, and this primary molded resin cools and solidifies, and the embedded portion 30 shown in Figs. 2A to 2H is injection-molded. In this state, a seal surface 32 is formed on the inner surface side of the flange portion 31 as a region between the edge of the movable mold 500 and the edge of the primary molding mold 600.

[0030] Fig. 5A shows the state in which the movable mold 500 is separated from the primary molding mold 600 together with the embedded portion 30 and joined to the secondary molding mold 700, starting from the state shown in Fig. 4C. In the secondary molding mold 700, a cavity corresponding to the outer portion 40 of the knock bar 11 is formed, and a secondary cavity 710 is formed by this cavity and the cavity on the side of the movable mold 500. This secondary cavity 710 surrounds the flange portion 31 of the embedded portion 30. In this state, the seal surface 32 of the flange portion 31 is in close contact with the parting surface P2 between the movable mold 500 and the secondary molding mold 700.

[0031] Fig. 5B shows the state in which the secondary molded resin is injected into the secondary cavity 710 shown in Fig. 5A through the secondary gate 525 from the secondary runner 520. In this state, the secondary cavity 710 is filled with the secondary molded resin, and this secondary molded resin cools and solidifies, and the covering portion 20 shown in Figs. 3A to 3D is injection-molded in a state of encompassing the embedded portion 30. Here, the seal surface 32 of the embedded portion 30 is crimped to the movable mold 500 at the parting surface between the movable mold 500 and the secondary molding mold 700. Therefore, the seal surface 32 prevents the secondary molded resin from leaking out to the functional portion 33 (see Fig. 2E), and as a result, the shape of the functional portion 33 is prevented from being deformed by the secondary molded resin.

[0032] Here, when the knock rod 11 as the writing instrument part 10 is used in a multi-color ballpoint pen as the writing instrument 100, each knock rod 11 is attached to a ballpoint pen refill containing ink of a different color. Then, while using the same color synthetic resin for the covering part 20, the knock rod 11 can be formed using synthetic resins of colors corresponding to the inks respectively for the embedding part 30. Thereby, it becomes possible to display the ink color of the ballpoint pen refill by the display part 35 of the embedding part 30.

[0033] Note that the knock rod 11 as the writing instrument part 10 of this embodiment can also be formed as shown in the modification example of FIG. 6. In this modification example, since the protruding part 34 of the embedding part 30 formed by primary molding is formed lower, the display part 35 is recessed from the surface of the knock protrusion 43. By forming it in this way, it becomes possible to distinguish by touch from the knock protrusion 43 of the knock rod 11 shown in FIG. 1A. Thereby, for example, the knock rod shown in FIG. 6 can be connected to a refill with a different function (for example, a mechanical pencil refill 220) or a refill with different ink properties (for example, the knock rod 11 of the above-described embodiment is used for a refill containing non-thermochromic ink, and the knock rod 11 of this modification example is used for a refill containing thermochromic ink, etc.) among the plurality of ballpoint pen refills 210 in the writing instrument 100 shown in FIG. 17B, and it also becomes possible to let the user perceive by touch that they are refills with different functions.

[0034] (2) Second Embodiment The writing instrument part 10 of the second embodiment of the present application is configured as a crown 12 attached to the rear end of the shaft cylinder 110 (see FIGS. 17A and 18A) of the writing instrument 100 as shown in FIG. 7E which is a front outer perspective view of FIG. 7A, a rear outer perspective view of FIG. 7B, a front view of FIG. 7C, a plan view of FIG. 7D, and a cross-sectional view taken along line VII-VII of FIG. 7C.

[0035] This crown 12 is composed of a substantially hemispherical exposed portion 60 and an insertion portion 61 as a functional portion 33 that protrudes from a support surface 22 that is the bottom surface of the exposed portion 60. The insertion portion 61 is formed on a substantially hollow cylinder, and two flanges 62 are formed on its outer peripheral surface. This insertion portion 61 is a portion that is inserted into the rear end of the shaft cylinder 110 (see FIGS. 17B and 18B) of the writing instrument 100. Further, the exposed portion 60 is a portion that is exposed to the outside as shown in FIGS. 17A and 18A when the crown 12 is attached to the rear end of the shaft cylinder 110 of the writing instrument 100.

[0036] As shown in FIG. 7E, the crown 12 is composed of components of an embedded portion 30 as a primary molded body and a covering portion 20 as a secondary molded body by two-color molding. The covering portion 20 and the embedded portion 30 are formed of synthetic resins of different materials. Specifically, the embedded portion 30 is formed of a synthetic resin that is more elastic.

[0037] The embedded portion 30 that constitutes the crown 12 of the present embodiment is shown in a front outer perspective view (FIG. 8A), a rear outer perspective view (FIG. 8B), a front view (FIG. 8C), a plan view (FIG. 8D), and a cross-sectional view taken along line VIII-VIII of FIG. 8C (FIG. 8E). The embedded portion 30 is composed of a disk-shaped flange portion 31, a seal surface 32 that is the inner surface of the flange portion 31, a functional portion 33 that protrudes from the seal surface 32 and is surrounded by a peripheral edge on the seal surface 32, and a protruding portion 34 that protrudes from the top surface of the flange portion 31. The protruding portion 34 is composed of a single cylindrical portion that protrudes from the flange portion 31 and a frustum-shaped portion on the rear side.

[0038] The covering portion 20 that constitutes the crown 12 of the present embodiment is shown in a front outer perspective view (FIG. 9A), a rear outer perspective view (FIG. 9B), a front view (FIG. 9C), a plan view (FIG. 9D), and a cross-sectional view taken along line IX-IX of FIG. 9C (FIG. 9E). The covering portion 20 generally shows a hemispherical shape, and a housing portion 21 (see FIGS. 9A and 9E), which is a space for housing a part of the functional portion 33 (specifically, the flange portion 31 and the protruding portion 34 shown in FIGS. 8A to 8E), is formed on the bottom surface side.

[0039] Here, a support surface 22 (see FIG. 9A), which is the bottom surface of the covering portion 20, and a sealing surface 32 (see FIG. 8A), which is the bottom surface of the flange portion 31 of the embedded portion 30, constitute a continuous surface on the crown 12 as shown in FIG. 7A.

[0040] The crown 12 of the present embodiment is formed by two-color molding of two types of synthetic resins. Specifically, the embedded portion 30 is formed by primary molding, and the covering portion 20 is formed by secondary molding. As a result, the flange portion 31 and the protruding portion 34 of the embedded portion 30 are in a state of being embedded in the accommodating portion 21 of the covering portion 20 (see FIG. 7E). A manufacturing method of this crown 12 will be described with reference to FIGS. 10A to 10C and FIGS. 11A and 11B.

[0041] FIG. 10A is a cross-sectional view showing a mold before primary molding, and shows a state in which a movable mold 500 and a primary molding mold 600 are joined. The movable mold 500 is provided with a through-hole having a circular cross-section, and a cylindrical core pin 530 is inserted into this through-hole. Further, a core pin outer peripheral cylinder 540 having a cylindrical diameter is inserted into a lower portion of the space between the movable mold 500 and the core pin 530. That is, the space formed by the movable mold 500, the core pin 530, and the core pin outer peripheral cylinder 540 becomes a cavity corresponding to the functional portion 33 of the embedded portion 30. A gate (not shown) into which primary molding resin is injected is provided in this cavity. On the other hand, the primary molding mold 600 is composed of a primary support mold 620 through which the movable mold 500 is inserted, and a primary split mold 630 supported by this primary support mold 620. Cavities corresponding to the flange portion 31 and the protruding portion 34 of the embedded portion 30 are formed in this primary split mold 630, and a primary cavity 610 is formed by this cavity and a part of the cavity of the movable mold 500 type. In this state, as shown in the enlarged view of FIG. 10B, an edge Q of the movable mold 500 on the split surface P1 of the primary cavity 610 is surrounded by an edge R of the primary molding mold 600 on this split surface P1.

[0042] The state in which the primary molding resin is injected into the primary cavity 610 shown in FIG. 10A is shown in FIG. 10C. In this state, the primary cavity 610 is filled with the primary molding resin, and this primary molding resin cools and solidifies to form the embedded portion 30 shown in FIGS. 8A to 8E by injection molding. In this state, a seal surface 32 is formed on the inner surface side of the flange portion 31 as a region between the edge of the movable mold 500 and the edge of the primary molding mold 600.

[0043] The state in which the movable mold 500 is separated from the primary molding mold 600 together with the embedded portion 30 and joined to the secondary molding mold 700 is shown in FIG. 11A from the state shown in FIG. 10C. The secondary molding mold 700 is composed of a secondary support mold 720 through which the movable mold 500 is inserted and a secondary split mold 730 supported by the secondary support mold 720. A cavity corresponding to the exposed portion of the crown 12 is formed in the secondary split mold 730, and a secondary cavity 710 is formed by this cavity and the cavity on the side of the movable mold 500. This secondary cavity 710 surrounds the flange portion 31 and the protruding portion 34 of the embedded portion 30. In this state, the seal surface 32 of the flange portion 31 is in close contact with the parting surface P2 between the movable mold 500 and the secondary molding mold 700.

[0044] The state in which the secondary molding resin is injected into the secondary cavity 710 shown in FIG. 11A through a gate (not shown) is shown in FIG. 11B. In this state, the secondary cavity 710 is filled with the secondary molding resin, and this secondary molding resin cools and solidifies to form the covering portion 20 shown in FIGS. 9A to 9E by injection molding in a state of surrounding the embedded portion 30. Here, the seal surface 32 of the embedded portion 30 is pressure-bonded to the movable mold 500 at the parting surface between the movable mold 500 and the secondary molding mold 700. Therefore, the seal surface 32 prevents the secondary molding resin from leaking out to the functional portion 33 (see FIG. 8A), and as a result, the shape of the functional portion 33 is prevented from being deformed by the secondary molding resin.

[0045] (3) Third Embodiment As shown in FIG. 12E, which is a front outer perspective view of FIG. 12A, a front inner perspective view of FIG. 12B, a front view of FIG. 12C, a right side view of FIG. 12D, and an XII-XII cross-sectional view of FIG. 12C, the writing instrument part 10 of the third embodiment of the present application is configured as a clip 13 attached near the rear end of the shaft cylinder 110 (see FIGS. 17A and 18A) of the writing instrument 100.

[0046] This clip 13 is composed of a slightly curved long plate-shaped extension part 71, a columnar fixing part 70 protruding inward from the rear end of the extension part 71, and a substantially hemispherical ball part 73 protruding inward from the tip of the extension part 71. The fixing part 70 is a part inserted into the rear end of the shaft cylinder 110 (see FIG. 17B) of the writing instrument 100. Further, the ball part 73 is a part that contacts the surface of the shaft cylinder 110 (see FIG. 17B) of the writing instrument 100. Furthermore, a substantially crescent-shaped display part 35 with a different color is provided near the tip of the outer surface of the extension part 71.

[0047] As shown in FIG. 12E, the clip 13 is composed of parts of an embedded part 30 as a primary molded body and a covering part 20 as a secondary molded body by two-color molding. The covering part 20 and the embedded part 30 are formed of synthetic resins with different colors.

[0048] The embedded part 30 constituting the clip 13 of the present embodiment is shown in a front outer perspective view (FIG. 13A), a front inner perspective view (FIG. 13B), a front view (FIG. 13C), a right side view (FIG. 13D), and an XIII-XIII cross-sectional view of FIG. 13C (FIG. 13E). The embedded part 30 is composed of a short square columnar flange part 31, a sealing surface 32 which is the inner surface of the flange part 31, a functional part 33 protruding substantially hemispherically from the sealing surface 32 and surrounded by the peripheral edge by the sealing surface 32, and a protruding part 34 protruding from the outer surface of the flange part 31. The protruding part 34 is formed in a thick substantially crescent shape.

[0049] The covering portion 20 that constitutes the clip 13 of the present embodiment is shown in a front outer perspective view (FIG. 14A), a front inner perspective view (FIG. 14B), a front view (FIG. 14C), a rear view (FIG. 14D), a right side view (FIG. 14E), and a cross-sectional view taken along line XIV-XIV of FIG. 14C (FIG. 14F). The covering portion 20 is composed of a slightly curved elongated plate-like extension portion 71 and a cylindrical fixing portion 70 that protrudes inward from the rear end of the extension portion 71. Near the tip of the extension portion 71, a housing portion 21 (see FIGS. 14B and 14F), which is a space for housing a part of the functional portion 33 (specifically, the flange portion 31 and the protruding portion 34 shown in FIGS. 8A to 8E), is formed. This housing portion 21 opens as a substantially crescent-shaped display opening 72 on the outer surface of the extension portion 71.

[0050] Here, the support surface 22 (see FIG. 14B), which is the bottom surface of the covering portion 20, and the seal surface 32 (see FIG. 13B), which is the bottom surface of the flange portion 31 of the embedded portion 30, constitute a continuous surface in the clip 13 as shown in FIG. 12B.

[0051] The clip 13 of the present embodiment is formed by two-color molding of two types of synthetic resin. Specifically, the embedded portion 30 is formed by primary molding, and the covering portion 20 is formed by secondary molding. As a result, the flange portion 31 and the protruding portion 34 of the embedded portion 30 are in a state of being embedded in the housing portion 21 of the covering portion 20 (see FIG. 12F). The manufacturing method of this clip will be described with reference to FIGS. 15A to 15C, FIGS. 16A, and 16B.

[0052] Figure 15A is a cross-sectional view showing the mold before primary molding, and shows a state in which the movable mold 500 and the primary molding mold 600 are joined. In the movable mold 500, a cavity corresponding to the ball portion 73 of the clip 13 is formed. On the other hand, in the primary molding mold 600, cavities corresponding to the flange portion 31 and the protruding portion 34 of the embedded portion 30 are formed, and a primary cavity 610 is formed by this cavity and a part of the cavity of the movable mold 500. The movable mold 500 is further provided with a primary gate 515 through which the primary molding resin is injected from the primary runner 510 into the primary cavity 610. In addition, a cavity in which the fixing portion 70 is to be formed later is also formed in the movable mold 500, and a secondary gate 525 through which the secondary molding resin is injected from the secondary runner 520 opens here. The movable mold 500 is further provided with two secondary runners 520 and two secondary gates 525. In this state, as shown in the enlarged view of FIG. 15B, the edge Q of the movable mold 500 on the parting surface P1 of the primary cavity 610 is surrounded by the edge R of the primary molding mold 600 on this parting surface P1.

[0053] The state in which the primary molding resin is injected from the primary runner 510 through the primary gate 515 into the primary cavity 610 shown in FIG. 15A is shown in FIG. 15C. In this state, the primary cavity 610 is filled with the primary molding resin, and this primary molding resin cools and solidifies to inject-mold the embedded portion 30 shown in FIGS. 13A to 13E. In this state, a seal surface 32 is formed on the inner surface side of the flange portion 31 as a region between the edge of the movable mold 500 and the edge of the primary molding mold 600.

[0054] FIG. 16A shows a state in which the movable mold 500 is separated from the primary molding mold 600 together with the embedded portion 30 and joined to the secondary molding mold 700 from the state shown in FIG. 15C. In the secondary molding mold 700, a cavity corresponding to the extended portion 71 of the clip 13 is formed, and a secondary cavity 710 is formed by this cavity and the cavity on the side of the movable mold 500. This secondary cavity 710 surrounds the flange portion 31 and the protruding portion 34 of the embedded portion 30. In this state, the seal surface 32 of the flange portion 31 is in close contact with the parting surface P2 between the movable mold 500 and the secondary molding mold 700.

[0055] The state in which secondary molding resin is injected into the secondary cavity 710 shown in FIG. 16A through the secondary runner 520 and the secondary gate 525 is shown in FIG. 16B. In this state, the secondary cavity 710 is filled with the secondary molding resin, and this secondary molding resin is cooled and solidified, and the covering portion 20 shown in FIGS. 14A to 14F is injection-molded in a state of enclosing the embedded portion 30. Here, the seal surface 32 of the embedded portion 30 is crimped to the movable mold 500 at the split surface between the movable mold 500 and the secondary molding mold 700. Therefore, the seal surface 32 prevents the secondary molding resin from leaking out to the ball portion 73 (see FIG. 12B) as the functional portion 33, and as a result, the shape of the functional portion 33 is prevented from being deformed by the secondary molding resin.

[0056] (4) Writing instrument The writing instrument 100 equipped with each writing instrument part 10 of the first to third embodiments is shown in a front view (Fig. 17A), a cross-sectional view taken along line XVII-XVII of Fig. 17A (Fig. 17B), a view from slightly to the right of Fig. 17A (Fig. 18A), and a cross-sectional view taken along line XVIII-XVIII of Fig. 18A (Fig. 18B). As shown in these figures, this writing instrument 100 houses a plurality of, specifically five refills 200, more specifically four ball pen refills 210 and one mechanical pencil refill 220, inside a shaft cylinder 110 composed of a front shaft 120 and a rear shaft 130. Different colored inks are housed in the four ball pen refills 210. At the rear end of each refill 200, a knock bar 11 as the writing instrument part 10 according to the first embodiment, which is composed of a covering part 20 and an embedded part 30, is attached. The embedded part 30 of the knock bar 11 attached to the ball pen refill 210 is formed of a synthetic resin of a color corresponding to the color and type of the corresponding ink. Thereby, the color of the ink in the ball pen refill 210 can be identified by the color of the display part 35 (see Fig. 1A) of the knock bar 11. Also, inside the shaft cylinder 110, a guide member 140 provided with five holes is attached, and each refill 200 is inserted through each hole. A spring 150 is externally inserted around the refill 200 to which the knock bar 11 is attached. The rear end of the spring 150 is supported by the front step 47 (see Fig. 1A) of the above-described knock bar 11, while the front end is supported by the guide member 140.

[0057] On the outer periphery of the rear shaft 130, five window holes 131 are provided along the longitudinal direction. From this window hole 131, a knock projection 43 (see Fig. 1A) of the knock bar 11 protrudes. This knock projection 43 is movable in the front-rear direction along the window hole 131. Also, a rear end hole 132 is provided at the rear end of the rear shaft 130, and a crown 12 as the writing instrument part 10 according to the second embodiment, which is composed of a covering part 20 and an embedded part 30, is attached here. Further, near the rear end of the rear shaft 130, a clip 13 as the writing instrument part 10 according to the third embodiment, which is composed of a covering part 20 and an embedded part 30, is attached.

[0058] There is a region on the outer periphery of the tip shaft 120 where a large number of fine grooves are formed along the longitudinal direction, and this region serves as a grip portion 122 for anti-slip. Also, the tip of the tip shaft 120 is tapered to have a reduced diameter, and a tip opening 121 is provided at its tip. When pressing in the direction of the tip of the knock projection 43 of the knock bar 11 described above, the corresponding refill 200 moves in the tip direction, and the writing tip thereof protrudes from this tip opening 121.

[0059] FIG. 19 is an enlarged perspective view showing the rear end portion of this writing instrument 100. As also shown in FIG. 18B, the knock bar 11 located on the right side of the clip 13 is connected to the mechanical pencil refill 220, and this knock bar 11 is the knock bar shown in FIG. 6. That is, this knock bar 11 is configured such that the display portion 35 is recessed from the display groove 44, unlike the knock bar 11 connected to the other ballpoint pen refill 210. Thereby, the mechanical pencil refill 220 can be identified from the other ballpoint pen refill 210 by the tactile sensation of the knock bar 11.

[0060] (5) Fourth Embodiment The writing instrument component 10 of the fourth embodiment of the present application is configured as a knock bar 11 as shown in FIG. 20G, which is a front outer perspective view of FIG. 20A, a front view of FIG. 20B, a rear view of FIG. 20C, a right side view of FIG. 20D, a bottom view of FIG. 20E, a plan view of FIG. 20F, and a cross-sectional view taken along XX-XX of FIG. 20A. Also, the state where the knock bar 11 is attached to the refill 200 is shown in the right side view of FIG. 21A, the cross-sectional view of FIG. 21B, and the partially enlarged cross-sectional view of FIG. 21C.

[0061] The writing instrument component 10 of the present embodiment is substantially the same as the first embodiment, but the difference lies in the step between the refill mounting portion 49 and the spring insertion portion 48, which are the mounting portions at the rear end of the refill 200. On the opposite side of the contact surface 53 (FIGS. 20A to 20E, FIG. 20G) where the rear end surface of the refill 200 abuts, a convex curved surface 54 formed in a curved surface shape protrudes in the direction of the axis.

[0062] As shown in FIGS. 21A and 21B, in a state where the knock bar 11 is attached to the refill 200, the refill attachment portion 49 of the knock bar 11 is inserted into the rear end of the refill 200 (FIG. 21C). However, since the contact surface 53 comes into contact with the rear end of the refill 200 and the knock bar 11 is not inserted any further, not all of the convex curved surface 54 is inserted into the rear end of the refill 200. Due to this convex curved surface 54, the tip side of the refill 200 with the knock bar 11 attached thereto will warp outward in the radial direction. As a result, contact and interference between the refills 200 due to the feeding of the refills 200 within the shaft cylinder of the refill 200 can be alleviated, and feeding failures can be prevented.

Industrial Applicability

[0063] The present invention can be used when forming writing instrument parts such as a knock bar, a crown, or a clip by two-color molding.

Explanation of Signs

[0064] 10 Writing instrument part 11 Knock bar 12 Crown 13 Clip 20 Coating part 21 Accommodating part 22 Support surface 30 Embedded part 31 Flange part 32 Sealing surface 33 Functional part 34 Protruding part 35 Display part 40 Outer part 41 Inner part 42 Inner step 43 Knock protrusion 44 Display groove 45 Wing-like part 46 Rear step 47 Front step 48 Spring outer insertion part 49 Refill attachment part 50 Locking protrusion 51 Release protrusion 52 Concave part 53 Contact surface 54 Convex curved surface 60 Exposed part 61 Insertion part 62 Flange 70 Fixing part 71 Extension part 72 Display opening 73 Ball part 100 Writing instrument 110 Shaft cylinder 120 Front shaft 121 Tip opening 122 Grip part 130 Rear shaft 131 Window hole 132 Rear end hole 140 Guide member 150 Spring 200 Refill, 210 Ball Pen Refill 220 Mechanical Pencil Refill 500 Movable Mold, 510 Primary Runner, 515 Primary Gate 520 Secondary Runner, 525 Secondary Gate, 530 Core Pin 540 Outer Periphery Cylinder of Core Pin 600 Primary Forming Mold, 610 Primary Cavity, 620 Primary Support Mold 630 Primary Split Mold 700 Secondary Forming Mold, 710 Secondary Cavity, 720 Secondary Support Mold 730 Secondary Split Mold P1 Split Surface of Primary Cavity P2 Split Surface between Movable Mold and Secondary Forming Mold Q Edge of Movable Mold, R Edge of Primary Mold

Claims

【Claim 1】 A writing instrument part comprising a covering part formed of synthetic resins of different materials from each other and an embedded part partially covered by the covering part, A functional part that is a part of the embedded part protrudes from a support surface that is a part of the covering part, A sealing surface that is a part of the embedded part is formed on the periphery of the functional part, The sealing surface forms a continuous surface with the support surface. Among the writing instrument parts, a manufacturing method of the writing instrument part by two-color molding in which the embedded part is formed by primary molding and the covering part is formed by secondary molding, The embedded part is formed by injection molding into a primary cavity formed by a movable mold and a primary molding mold, An edge of the movable mold at a split surface of the primary cavity is surrounded by an edge of the primary molding mold at the split surface, The sealing surface is formed between the edge of the movable mold and the edge of the primary molding mold, and The sealing surface is pressed against the movable mold at a split surface between the movable mold and a secondary molding mold during the secondary molding. A manufacturing method of the writing instrument part.

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