Manufacturing method for producing resin moldings including clip part for writing instruments

Abstract

To provide a manufacturing method for producing a resin molding including a clip part of a writing instrument, capable of enhancing shape accuracy of the clip part.SOLUTION: The present invention relates to a manufacturing method for producing a resin molding including a clip part of a writing instrument, which uses a right side auxiliary member which constitutes a part of a cavity side inner surface defining a right side cavity of a right side mold and is capable of protruding and moving inward of the right side cavity, and a left side auxiliary member which constitutes a part of a cavity side inner surface defining a left side cavity of the left side mold and is capable of protruding and moving inward of the left side cavity. After the molding step, the right side mold and the left side mold are separated from each other to separate the right side cavity and the left side cavity from each other, and the left side auxiliary member is projected to the inside of the left side cavity while the right side auxiliary member is projected to the inside of the right side cavity to maintain the resin molded molding sandwiched between the right side auxiliary member and the left side auxiliary member.SELECTED DRAWING: Figure 14

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a resin molded product including a clip portion of a writing instrument, and to an apparatus for manufacturing a resin molded product including a clip portion of a writing instrument.Furthermore, the present invention relates to a resin molded product manufactured by the manufacturing method or the manufacturing apparatus. [Background technology]

[0002] 2. Description of the Related Art Writing implements such as ballpoint pens have been developed and sold in a variety of designs.

[0003] In a typical configuration, a writing instrument has a clip portion that extends in the front-rear direction (longitudinal direction) (see Figs. 1 to 3). The clip portion usually has a smooth design on the front side (sometimes the product brand name is printed on it), while the back side has a gap narrowing protrusion (called a "ball") that narrows the gap between the back side and the barrel surface so that the writing instrument can be held (clipped) to a piece of fabric such as a pocket.

[0004] In a writing instrument having a pen tip extension / retraction function, the clip portion may also function as a knock member for operating the pen tip extension / retraction function. The examples described below are examples that also function as such knock members. However, the "clip portion" in this specification is not limited by the presence or absence of such a knock member function, at least at the time of filing this application.

[0005] The resin molded product including the clip portion is obtained by molding a synthetic resin (for example, polycarbonate resin).

[0006] More specifically, the mold is manufactured using a right-side mold having a right-side cavity corresponding to the right contour of the clip portion and a left-side mold having a left-side cavity corresponding to the left contour of the clip portion, the manufacturing method including a mold closing process in which the right-side mold and the left-side mold are adjacent to each other to partition a molding space with the right-side cavity and the left-side cavity, a molding process in which a resin material is injected into the molding space to mold a resin molded product, and a mold opening process in which the right-side mold and the left-side mold are separated from each other to remove the resin molded product.

[0007] Such a manufacturing method and manufacturing device are described, for example, in Patent Document 1. According to FIG. 3 and paragraph 0011 of Patent Document 1, it is explained that a resin molded product including a clip part can be divided into two parts at the center plane in the left-right direction and mass-produced by injection molding using a split mold for the two parts.

[0008] A similar explanation is given in Patent Document 2. According to Figures 1, 2, 5, and 7 of Patent Document 2 and the description in paragraph 0008, it is explained that a resin molded product including a clip portion can be divided into two at the center plane in the left-right direction and injection molded using a cavity block that is a split mold for the two parts. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Utility Model Application Publication No. 7-5785 [Patent Document 2] JP 2010-260210 A Summary of the Invention [Problem to be solved by the invention]

[0010] The present inventors have found that in the conventional manufacturing methods as described above, there may be cases where the shape precision of the clip portion is insufficient.

[0011] Specifically, in the mold opening process in which the right-side mold and the left-side mold are separated from each other to remove the resin molded product, the timing at which the resin molded product separates from each of the right-side mold and the left-side mold may not be completely simultaneous, and in such cases, the resin molded product may remain attached to only one of the right-side mold or the left-side mold. At this time, if the right-side mold or the left-side mold to which it remains attached moves further for the opening operation, the resin molded product may be affected by the movement (moving together while still attached), and undesired bending may occur.

[0012] This type of bending mars the aesthetic look of the writing instrument. Consumers have a very sensitive sense of aesthetics when it comes to writing instruments, so lowering product precision can be an obstacle to increasing the popularity and sales of the product. On the other hand, increasing product precision can lead to a higher defective rate, which can lead to higher costs.

[0013] In addition, depending on the degree to which the molded product continues to adhere to only one of the molds, the molded product may have undesired "scratches" (dropout scratches) (which will of course result in a defective product). This can be a problem, particularly when the molded product has a design with fine concave-convex patterns.

[0014] Furthermore, when the clip portion also serves as a knock member, there is a possibility that the clip portion may not move properly (for example, may not slide properly against the barrel surface) depending on the degree of bending (which will naturally result in a defective product).

[0015] The inventors of the present invention found through various experiments that the above-mentioned problems can be avoided to some extent by waiting until the resin molded product has fully solidified (after a predetermined time has elapsed when it is expected that the resin molded product will have fully solidified) before carrying out the mold opening step. However, such a workaround hinders the shortening of the manufacturing time, and does not completely (or significantly) avoid the above-mentioned problems.

[0016] The present invention has been made based on the above-mentioned background, and its object is to provide a manufacturing method for manufacturing a resin molded product including a clip portion of a writing instrument, which can improve the shape accuracy of the clip portion. [Means for solving the problem]

[0017] The present invention relates to a method for producing a resin molded product including a clip portion of a writing instrument, the method comprising: a right-side mold having a right cavity corresponding to the right contour of the clip portion; a left-side mold having a left cavity corresponding to the left contour of the clip portion; a right auxiliary member constituting a part of the cavity-side inner surface defining the right cavity of the right-side mold and movable to protrude inwardly into the right cavity; and a left auxiliary member constituting a part of the cavity-side inner surface defining the left cavity of the left-side mold and movable to protrude inwardly into the left cavity, the right-side mold and the left-side mold being adjacent to each other to define a molding space by the right cavity and the left cavity. a molding step of, after the mold closing step, injecting a resin material into the molding space to mold the resin molded product; a first mold opening step of, after the molding step, separating the right-side mold and the left-side mold from each other to separate the right cavity and the left cavity from each other, while causing the right auxiliary member to protrude into the inside of the right cavity and the left auxiliary member to protrude into the inside of the left cavity, thereby maintaining a state in which the resin molded product is sandwiched between the right auxiliary member and the left auxiliary member; and a second mold opening step of, after the first mold opening step, separating the right auxiliary member and the left auxiliary member from the resin molded product.

[0018] According to the method of the present invention, when the right and left molds are separated from each other to separate the right and left cavities from each other, the right auxiliary member is protruded toward the inside of the right cavity while the left auxiliary member is protruded toward the inside of the left cavity, so that the resin molded product is maintained in a state where it is sandwiched between the right and left auxiliary members. As a result, while the resin molded product is in this sandwiched state, all areas excluding the sandwiched parts are separated from the right and left molds first, which significantly prevents the resin molded product from bending due to continued adhesion to the right or left mold.

[0019] In the method of the present invention, in a state in which the molding space is partitioned, it is preferable that the right abutment portion, which is a part of the right auxiliary member, and the left abutment portion, which is a part of the left auxiliary member, abut against each other, and that the right abutment portion and the left abutment portion abut against each other even during the first mold opening step.

[0020] In this case, it is possible to bias the right auxiliary member and the left auxiliary member against each other while the molding space is partitioned, which makes it easy to improve the function of each of the right auxiliary member and the left auxiliary member as a part of the cavity-side inner surface (the shape accuracy as the cavity-side inner surface).

[0021] Alternatively, in the method of the present invention, it is preferable that, in a state in which the molding space is partitioned, both the right abutment portion that is a part of the right auxiliary member and the left abutment portion that is a part of the left auxiliary member abut against positioning stopper portions provided independently of the right-side mold and the left-side mold, and that the right abutment portion and the left abutment portion abut against the positioning stopper portions even during the first mold opening step.

[0022] In this case, it is possible to bias the right and left auxiliary members against the positioning stopper portions while the molding space is partitioned. This makes it easy to improve the function of the right and left auxiliary members as part of the cavity-side inner surface (the shape accuracy as the cavity-side inner surface). Furthermore, in this case, even if an imbalance occurs between the biasing force of the right auxiliary member and the biasing force of the left auxiliary member, one does not push the other, so an even greater effect in preventing bending can be expected.

[0023] In addition, in the method of the present invention, it is preferable that the right auxiliary member is capable of protruding and moving inwardly of the right cavity by the biasing force of an elastic member (e.g., a coil spring), and the left auxiliary member is also capable of protruding and moving inwardly of the left cavity by the biasing force of an elastic member (e.g., a coil spring).

[0024] This makes it possible to achieve the protruding movement performance of the right auxiliary member and the left auxiliary member with an extremely simple and compact configuration.

[0025] According to the actual verification by the inventor of the present invention, a very shallow (specifically, 0.005 mm to 0.3 mm deep, preferably 0.02 mm to 0.05 mm deep) pressure mark or abutment mark remains in the portion sandwiched between the right auxiliary member and the left auxiliary member in the first mold opening step. (In other words, if such a very shallow pressure mark or abutment mark remains, it is considered that the mold was manufactured by the method of the present invention.) It is preferable that such a pressure mark or abutment mark remains in an inconspicuous portion. In general, the clip portion has a gap narrowing convex portion on the back side, and the gap narrowing convex portion is an inconspicuous portion. Therefore, it is preferable that the gap narrowing convex portion is sandwiched between the right auxiliary member and the left auxiliary member in the first mold opening step.

[0026] The present invention also relates to a manufacturing device for manufacturing a resin molded product including a clip portion of a writing implement, comprising: a right-side mold having a right cavity corresponding to the right contour of the clip portion; a left-side mold having a left cavity corresponding to the left contour of the clip portion; a right auxiliary member constituting a part of the cavity-side inner surface that defines the right cavity of the right-side mold and capable of protruding inwardly into the right cavity; and a left auxiliary member constituting a part of the cavity-side inner surface that defines the left cavity of the left-side mold and capable of protruding inwardly into the left cavity. the right-side mold and the left-side mold are moved adjacent to each other to partition a molding space by the right cavity and the left cavity, and are moved away from each other to open the molding space, and when the molding space is opened, the right auxiliary member protrudes into the inside of the right cavity and the left auxiliary member protrudes into the inside of the left cavity, so that a state in which a resin molded product after molding is sandwiched between the right auxiliary member and the left auxiliary member is temporarily maintained.

[0027] According to the device of the present invention, when the molding space is opened, the right auxiliary member protrudes inward into the right cavity and the left auxiliary member protrudes inward into the left cavity, so that the resin molded product after molding is temporarily held between the right auxiliary member and the left auxiliary member. With the resin molded product held in this manner, all areas except for the held portions are first separated from the right mold and the left mold, so that bending of the resin molded product due to continued adhesion to the right mold or the left mold is significantly suppressed.

[0028] In the device of the present invention, when the molding space is partitioned, the right abutment portion, which is a part of the right auxiliary member, and the left abutment portion, which is a part of the left auxiliary member, are adapted to abut against each other, and it is preferable that the right abutment portion and the left abutment portion are adapted to abut against each other even while the state in which the resin molded product is sandwiched between the right auxiliary member and the left auxiliary member is temporarily maintained.

[0029] In this case, it is possible to bias the right auxiliary member and the left auxiliary member against each other while the molding space is partitioned, which makes it easy to improve the function of each of the right auxiliary member and the left auxiliary member as a part of the cavity-side inner surface (the shape accuracy as the cavity-side inner surface).

[0030] Alternatively, the device of the present invention preferably further comprises positioning stopper portions provided independently of the right-side mold and the left-side mold, so that when the molding space is partitioned, both the right abutment portion which is a part of the right auxiliary member and the left abutment portion which is a part of the left auxiliary member abut against the positioning stopper portions, and the right abutment portion and the left abutment portion abut against the positioning stopper portions even while the state in which the resin molded product is sandwiched between the right auxiliary member and the left auxiliary member is temporarily maintained.

[0031] In this case, it is possible to bias the right and left auxiliary members against the positioning stopper portions while the molding space is partitioned. This makes it easy to improve the function of the right and left auxiliary members as part of the cavity-side inner surface (the shape accuracy as the cavity-side inner surface). Furthermore, in this case, even if an imbalance occurs between the biasing force of the right auxiliary member and the biasing force of the left auxiliary member, one does not push the other, so an even greater effect in preventing bending can be expected.

[0032] In addition, in the device of the present invention, it is preferable that the right auxiliary member is capable of protruding and moving toward the inward side of the right cavity by the biasing force of an elastic member (e.g., a coil spring), and the left auxiliary member is also capable of protruding and moving toward the inward side of the left cavity by the biasing force of an elastic member (e.g., a coil spring).

[0033] This makes it possible to achieve the protruding movement performance of the right auxiliary member and the left auxiliary member with an extremely simple and compact configuration.

[0034] As described above, according to the inventor's actual verification, a very shallow (specifically, 0.005 mm to 0.3 mm deep) pressure contact mark or contact mark remains at the portion sandwiched between the right auxiliary member and the left auxiliary member. Therefore, it is preferable that the gap narrowing convex portion is sandwiched between the right auxiliary member and the left auxiliary member.

[0035] The present invention also relates to a resin molded product produced by the method of the present invention.

[0036] The present invention further relates to a writing instrument comprising a resin molded article produced by the method of the present invention. Effect of the Invention

[0037] According to the method of the present invention, when the right and left molds are separated from each other to separate the right and left cavities from each other, the right auxiliary member is protruded toward the inside of the right cavity while the left auxiliary member is protruded toward the inside of the left cavity, so that the resin molded product is maintained in a state where it is sandwiched between the right and left auxiliary members. As a result, while the resin molded product is in this sandwiched state, all areas excluding the sandwiched parts are separated from the right and left molds first, which significantly prevents the resin molded product from bending due to continued adhesion to the right or left mold.

[0038] According to the device of the present invention, when the molding space is opened, the right auxiliary member protrudes inward into the right cavity and the left auxiliary member protrudes inward into the left cavity, so that the resin molded product after molding is temporarily held between the right auxiliary member and the left auxiliary member. With the resin molded product held in this manner, all areas except for the held portions are first separated from the right mold and the left mold, so that bending of the resin molded product due to continued adhesion to the right mold or the left mold is significantly suppressed. [Brief description of the drawings]

[0039] [Figure 1] 1 is a schematic perspective view of a writing instrument including a resin molded product produced by the method of the present invention. [Diagram 2] FIG. 2 is a side view of the writing instrument of FIG. [Diagram 3] FIG. 2 is a vertical cross-sectional view of the writing instrument of FIG. [Figure 4] 2 is a perspective view showing a resin molded product including a clip portion, which is a part of the writing implement in FIG. 1. FIG. [Diagram 5] FIG. 5 is a side view of the resin molded product of FIG. [Figure 6] 1 is a schematic cross-sectional view of a manufacturing apparatus according to a first embodiment of the present invention for carrying out a method of the present invention, showing a state after a mold closing step has been performed. [Figure 7] FIG. 7 is a schematic cross-sectional view of the manufacturing apparatus of FIG. 6, showing a state in which a first mold opening step is being performed. [Figure 8] FIG. 7 is a schematic cross-sectional view of the manufacturing apparatus of FIG. 6, showing the state after a second mold opening step has been performed. [Figure 9] 7 is a schematic perspective view showing a state after a mold closing step of the manufacturing apparatus in FIG. 6 is performed. [Figure 10] 7 is a schematic perspective view showing a state in which a first mold opening step is being performed by the manufacturing apparatus in FIG. 6. [Figure 11] 7 is a schematic perspective view showing a state in which a first mold opening step is being performed on the left side portion of the manufacturing apparatus in FIG. 6. [Figure 12]7 is a schematic perspective view showing a state after a second mold opening step has been performed in the manufacturing apparatus of FIG. 6. FIG. [Figure 13] FIG. 2 is a schematic cross-sectional view of a manufacturing apparatus according to a second embodiment of the present invention for carrying out a method of the present invention, showing a state after a mold closing step has been performed. [Figure 14] FIG. 14 is a schematic cross-sectional view of the manufacturing apparatus of FIG. 13, showing a state in which a first mold opening step is being performed. [Figure 15] FIG. 14 is a schematic cross-sectional view of the manufacturing apparatus of FIG. 13, showing the state after the second mold opening step has been performed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] (Configuration of Writing Instrument 1) First, an embodiment of a writing instrument including a resin molded product produced by the method of the present invention will be described. Fig. 1 is a schematic vertical cross-sectional view of the writing instrument 1 of this embodiment, Fig. 2 is a side view of the writing instrument 1 of this embodiment, and Fig. 3 is a vertical cross-sectional view of the writing instrument 1 of this embodiment. Fig. 4 is a perspective view of a resin molded product 10 including a clip, which is a part of the writing instrument 1 of this embodiment, and Fig. 5 is a side view of the resin molded product 10 of Fig. 4.

[0041] 1 to 5, the writing instrument 1 of this embodiment includes a resin molded product 10 having a clip portion. The clip portion is formed by a clip main body 11 and a gap narrowing protrusion 12 on the back side of the clip main body 11. As will be described later, the configuration is generally similar to that of a conventional writing instrument, except that there are pressure contact marks or contact marks (region 12a on the front side below the dashed line in FIG. 5) on both the left and right sides of the gap narrowing protrusion 12.

[0042] More specifically, the writing instrument 1 has a clip body 11 that extends in the front-rear direction (longitudinal direction). A smooth design is adopted on the front side of the clip body 11 (a product brand name or the like can be printed on it). The back side of the clip body 11 is provided with a gap narrowing protrusion 12 (called a "ball") for narrowing the gap between the back side and the surface of the barrel side in order to be held (clipped) to a piece of fabric such as a pocket.

[0043] In addition, the clip body 11 of this embodiment also serves as a knock member for operating the pen tip extension and retraction function. For this reason, the rear end of the clip body 11 is connected to a tube 14 via a connection part 13, and a cam surface 14c is formed on the front side of the tube 14. The tube 14 is housed in the barrel of the writing instrument 1.

[0044] As the clip main body 11 is moved forward (knocking action), the cam surface 14c cooperates with corresponding components inside the barrel (detailed explanation omitted), so that the pen tip is alternately selected (locked) into an extended or retracted state.

[0045] (Apparatus for manufacturing resin molded product 10 (first embodiment)) The resin molded product 10 is manufactured by injection molding of a resin material (e.g., PC, PP, PE, ABS, AS, PS, PMMA, PA, PET, PBT, POM, or a polymer alloy or polymer blend thereof).

[0046] 6 to 8 are schematic cross-sectional views of a manufacturing apparatus according to a first embodiment of the present invention for carrying out the method of the present invention. The cross-section corresponds to the cross-section of the resin molded product 10 in production taken along the line AA in FIG. 5. FIG. 6 shows the state after the mold closing step, FIG. 7 shows the state during the first mold opening step, and FIG. 8 shows the state after the second mold opening step. Also, FIGS. 9 to 12 are schematic perspective views of the manufacturing apparatus according to this embodiment. FIG. 9 shows the state after the mold closing step, FIG. 10 shows the state during the first mold opening step, FIG. 11 shows the state during the first mold opening step for the left side portion, and FIG. 12 shows the state after the second mold opening step.

[0047] 6 to 12, the manufacturing apparatus of this embodiment includes a right-side mold 20 having a right cavity 21 corresponding to the right contour of the clip part (the clip body part 11 and the gap narrowing protrusion part 12), and a left-side mold 40 having a left cavity 41 corresponding to the left contour of the clip part. Each of the molds 20, 40 is made of, for example, hardened steel or pre-hardened steel.

[0048] A right auxiliary member 30 is provided which constitutes a part of the cavity-side inner surface (designated by reference number 31 in the drawings) that defines the right cavity 21 of the right mold 20 and which is movable and protrudes inward of the right cavity (to the left in FIGS. 6 to 8). Symmetrically, a left auxiliary member 50 is provided which constitutes a part of the cavity-side inner surface (designated by reference number 51 in the drawings) that defines the left cavity 41 of the left mold 40 and which is movable and protrudes inward of the left cavity (to the right in FIGS. 6 to 8). Each auxiliary member 30, 50 is also made of, for example, hardened steel or pre-hardened steel.

[0049] As shown in Figs. 10 and 11, the right auxiliary member 30 has a rectangular parallelepiped sliding portion 33 with a slightly flat cross section (e.g., approximately 8 mm × 2.3 mm), and as shown in Figs. 6 to 8, the sliding portion 33 slidably penetrates the wall portion 26 on the right cavity side of the right-side mold 20.

[0050] A part of the exposed end side (the left end side in Figs. 6 to 8) of the sliding part 33 constitutes a part (indicated by reference numeral 31 in the figures) of the cavity-side inner surface that defines the right cavity 21. Meanwhile, the remaining part of the exposed end side (the left end side in Figs. 6 to 8) of the sliding part 33 serves as the right abutment part 32 and abuts against a left abutment part 52 on the exposed end side of the sliding part 53 of the left auxiliary member 50 described later (they are actually abutting against each other in the states of Figs. 6 and 7).

[0051] The rear side of the sliding portion 33 is connected to a cylindrical flange portion 34 , and the cylindrical flange portion 34 is movable in the axial direction of the sliding portion 53 within an accommodation space 25 provided in the right-side mold 20 .

[0052] More specifically, a cylindrical guide portion 23 extends from the right end wall 22 of the right mold 20 into the accommodation space 25, and the cylindrical flange portion 34 is movable using the cylindrical guide portion 23 as a guide.

[0053] In addition, a coil spring 24 is interposed between the right end wall 22 and the cylindrical flange portion 34, and biases the sliding portion 33 toward the exposed end. In the states of Fig. 7 and Fig. 8, the cylindrical flange portion 34 abuts against the wall portion 26 on the right cavity side, i.e., the coil spring 24 is in a maximally extended state, but even in these states, the coil spring 24 is compressed from its natural state.

[0054] The coil spring 24 has, for example, a wire diameter of 0.65 mm, a coil diameter of 5 mm, a natural length of 15 mm, a tight length of 6.5 mm, a spring constant of 2.9 N / mm, a compressed length of 10 mm in the state shown in FIG. 6, and a compressed length of 12.5 mm in the states shown in FIGS.

[0055] The left auxiliary member 50 is symmetrical to the right auxiliary member 30, and has a rectangular parallelepiped sliding part 53 with a slightly flat cross section (for example, about 8 mm × 2.3 mm) as shown in Figs. 10 and 11, and the sliding part 53 slidably penetrates the wall part 46 on the left cavity side of the left-side mold 40 as shown in Figs. 6 to 8.

[0056] A part of the exposed end side (the right end side in Figs. 6 to 8) of the sliding part 53 constitutes a part (indicated by reference numeral 51 in the figures) of the cavity side inner surface that defines the left cavity 41. On the other hand, the remaining part of the exposed end side (the left end side in Figs. 6 to 8) of the sliding part 53 serves as the left abutment part 52 and abuts against the right abutment part 32 on the exposed end side of the sliding part 33 of the right auxiliary member 30 (they actually abut against each other in the states of Figs. 6 and 7).

[0057] The rear side of the sliding portion 53 is connected to a cylindrical flange portion 54 , and the cylindrical flange portion 54 is movable in the axial direction of the sliding portion 53 within an accommodation space 45 provided in the left-side mold 40 .

[0058] More specifically, a cylindrical guide portion 43 extends from the left end wall 42 of the left mold 40 into the accommodation space 45, and the cylindrical flange portion 54 is movable using the cylindrical guide portion 43 as a guide.

[0059] In addition, a coil spring 44 is interposed between the left end wall 42 and the cylindrical flange portion 54, and biases the sliding portion 53 toward the exposed end. In the states of Fig. 7 and Fig. 8, the cylindrical flange portion 54 abuts against the wall portion 46 on the right hollow side, that is, the coil spring 44 is in a maximally extended state, but even in this state, the coil spring 44 is compressed from its natural state.

[0060] The coil spring 44 has the same dimensions as the coil spring 24, for example, a wire diameter of 0.65 mm, a coil diameter of 5 mm, a natural length of 15 mm, a tight length of 6.5 mm, a spring constant of 2.9 N / mm, a compressed length of 10 mm in the state shown in Figure 6, and a compressed length of 12.5 mm in the states shown in Figures 7 and 8.

[0061] Substantially similar to the conventional structure, the right-side mold 20 and the left-side mold 40 are moved adjacent to each other to partition the molding space by the right cavity 21 and the left cavity 41 (the state shown in FIG. 6). The right-side mold 20 and the left-side mold 40 are also moved away from each other to open the molding space (the states shown in FIGS. 7 and 8). Each mold 20, 40 moves by sliding along a guide rail (not shown), so each mold 20, 40 is also called a "slide cavity."

[0062] On the other hand, as a feature of this embodiment, when the molding space is opened, the right auxiliary member 30 is protruded toward the inside of the right cavity 21 (the left side in Figs. 6 to 8) and the left auxiliary member 50 is protruded toward the inside of the left cavity 41 (the right side in Figs. 6 to 8) by the urging force applied from the coil spring 24 to the cylindrical flange portion 34 of the right auxiliary member 30 and the urging force applied from the coil spring 44 to the cylindrical flange portion 54 of the left auxiliary member 50 (the state in Fig. 7). As a result, the state in which the resin molded product 10 after molding is sandwiched between the right auxiliary member 30 and the left auxiliary member 50 is temporarily maintained.

[0063] In this embodiment, region 12a (the region below and in front of the dashed line in FIG. 5) of gap narrowing protrusion 12 in resin molded product 10 after molding is clamped between right auxiliary member 30 and left auxiliary member 50. The gap narrowing protrusion 12 has a left-right thickness of about 1.0 mm, a front-rear length of region 12a of about 9.7 mm, and a height of region 12a of about 2.7 mm.

[0064] Additionally, in this embodiment, the front core pin 60 (see FIGS. 9 to 12) for molding the cam surface 14c of the cylindrical portion 14 also contributes to the formation of the molding space.

[0065] (Function of Manufacturing Apparatus for Resin Molded Product 10 (Manufacturing Method)) First, the right-side mold 20 and the left-side mold 40 are moved so as to be adjacent to each other, and the molding space is defined by the right-side cavity 21 and the left-side cavity 41 (mold closing step: the state shown in FIG. 6). At this time, in this embodiment, the front-side core pin 60 (see FIGS. 9 to 12) also contributes to the formation of the molding space.

[0066] Next, a resin material is injected into the molding space to form the resin molded product 10 (molding step).

[0067] Then, the right mold 20 and the left mold 40 are moved away from each other to open the molding space (first mold opening step: state in FIG. 7). At this time, the right auxiliary member 30 is protruded inwardly into the right cavity 21 and the left auxiliary member 50 is protruded inwardly into the left cavity 41 by the biasing force imparted from the coil spring 24 to the right auxiliary member 30 and the biasing force imparted from the coil spring 44 to the left auxiliary member 50. This temporarily maintains the state in which the molded resin molded product 10 is sandwiched between the right auxiliary member 30 and the left auxiliary member 50 after molding.

[0068] Thereafter, the right-side mold 20 and the left-side mold 40 are moved further away from each other, the abutting state between the right abutment portion 32 of the right auxiliary member 30 and the left abutment portion 52 of the left auxiliary member 50 is released, and the right auxiliary member 30 and the left auxiliary member 50 are separated from the resin molded product 10. (Second mold opening step: the state in FIG. 8).

[0069] As described above, according to the manufacturing apparatus or method of this embodiment, when the right-side mold 20 and the left-side mold 40 are separated from each other to separate the right cavity 21 and the left cavity 41 from each other, the right auxiliary member 30 is protruded toward the inside of the right cavity while the left auxiliary member 50 is protruded toward the inside of the left cavity, so that the resin molded article 10 is maintained in a state in which it is sandwiched between the right auxiliary member 30 and the left auxiliary member 50. As a result, while the resin molded article 10 is in this sandwiched state, all areas except for the sandwiched portion are separated first from the right-side mold 20 and the left-side mold 40, so that bending of the resin molded article 10 due to continued adhesion to the right-side mold 20 or the left-side mold 40 is significantly suppressed.

[0070] According to the manufacturing device or manufacturing method of this embodiment, in a state in which the molding space is partitioned (see FIG. 6), the right contact portion 32 which is a part of the right auxiliary member 30 and the left contact portion 52 which is a part of the left auxiliary member 50 are biased toward each other. This improves the function as a part of the cavity-side inner surface of each of the right auxiliary member 30 and the left auxiliary member 50 (the shape accuracy of the regions 31, 51 as a part of the cavity-side inner surface).

[0071] Furthermore, according to the manufacturing device or manufacturing method of this embodiment, the right auxiliary member 30 is capable of protruding and moving inwardly of the right cavity 21 by the biasing force of the coil spring 24, and the left auxiliary member 50 is also capable of protruding and moving inwardly of the left cavity 41 by the biasing force of the coil spring 44. With this configuration, the protruding movement performance of the right auxiliary member 30 and the left auxiliary member 50 can be designed or realized as desired, despite the extremely simple and compact configuration.

[0072] According to actual verification by the present inventors, in this embodiment, an extremely shallow (specifically, 0.005 mm to 0.3 mm deep, preferably 0.02 mm to 0.05 mm deep) pressure mark or contact mark remains in the portion (region 12a of gap narrowing protrusion 12) sandwiched between right auxiliary member 30 and left auxiliary member 50. Conversely, when such an extremely shallow pressure mark or contact mark remains, it is considered to have been manufactured by the method of the present invention.

[0073] (Apparatus for manufacturing resin molded product 10 (second embodiment)) 13 to 15 are schematic cross-sectional views of a manufacturing apparatus according to a second embodiment of the present invention for carrying out the method of the present invention. These cross sections also correspond to the cross section of the resin molded product 10 in production taken along line AA in Fig. 5. Fig. 13 shows the state after the mold closing step has been performed, Fig. 14 shows the state during the first mold opening step, and Fig. 15 shows the state after the second mold opening step has been performed.

[0074] The manufacturing apparatus of this embodiment includes a positioning stopper portion 70 provided independently of the right mold 20 and the left mold 40 .

[0075] In addition to (or instead of) the right abutment portion 32 on the exposed end side of the sliding portion 33 and the left abutment portion 52 on the exposed end side of the sliding portion 53 abutting against each other, each of them abuts against the positioning stopper portion 70. (If the right abutment portion 32 and the left abutment portion 52 do not abut against each other, the right abutment portion 32, the left abutment portion 52, and the positioning stopper portion 70 (the upper surface) can define a "shape" for the gap narrowing protrusion 12.)

[0076] Other configurations of this embodiment are similar to those of the manufacturing apparatus of embodiment 1. In Figures 13 to 15, components similar to those of embodiment 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0077] According to the manufacturing device or manufacturing method of this embodiment, in a state in which the molding space is partitioned (see FIG. 13), the right contact portion 32 which is a part of the right auxiliary member 30 and the left contact portion 52 which is a part of the left auxiliary member 50 are each biased against the positioning stopper portion 70. This improves the function as a part of the cavity-side inner surface of each of the right auxiliary member 30 and the left auxiliary member 50 (the shape accuracy of the regions 31, 51 as a part of the cavity-side inner surface).

[0078] Furthermore, according to this embodiment, even if an imbalance occurs between the biasing force of the coil spring 24 on the right auxiliary member 30 and the biasing force of the coil spring 44 on the left auxiliary member 50, one does not push the other, so an even greater effect in preventing bending can be expected. [Explanation of symbols]

[0079] 1 writing implements 10 Resin molded products 11 Clip body (clip part) 12. Convex part for narrowing the gap (clip part) 12a area 13 Connection 14 Cylinder part 14c Cam surface 20 Right side mold 21 Right cavity 22 Right end wall 23 Cylindrical guide 24 Coil spring 25 Containment Space 26 Wall 30 Right auxiliary member 31 Area as part of the cavity side inner surface 32 Right side contact part 33 Sliding part 34 Cylindrical flange part 40 Left side mold 41 Left cavity 42 Left end wall 43 Cylindrical guide 44 Coil spring 45 Containment Space 46 Wall 50 Left support member 51 Area as part of the cavity side inner surface 52 Left contact part 53 Sliding part 54 Cylindrical flange part 60 Front core pin 70 Positioning stopper

Claims

1. A manufacturing method for producing a resin molded product including the clip portion of a writing instrument, A right-side mold having a right-side cavity corresponding to the right-side contour of the clip portion, A left-side mold having a left-side cavity corresponding to the left contour of the clip portion, A right auxiliary member, which constitutes a part of the inner surface on the cavity side that demarcates the right cavity of the right mold, and which is movable to protrude inward from the right cavity, A left-side auxiliary member that forms a part of the inner surface on the cavity side that demarcates the left-side cavity of the left-side mold, while being movable to protrude inward into the left-side cavity, Using A mold closing step is performed by placing the right side mold and the left side mold adjacent to each other, thereby dividing the molding space with the right side cavity and the left side cavity. After the mold closing step, a molding step is performed in which a resin material is injected into the molding space to form the resin molded product. A first mold opening step is performed after the molding step, in which the right mold and the left mold are separated from each other, thereby separating the right cavity and the left cavity from each other, while the right auxiliary member is made to protrude inward into the right cavity and the left auxiliary member is made to protrude inward into the left cavity, thereby maintaining a state in which the resin molded product is sandwiched between the right auxiliary member and the left auxiliary member. After the first mold opening step, a second mold opening step is performed to separate the right auxiliary member and the left auxiliary member from the resin molded product, A manufacturing method characterized by comprising the following:

2. In the state in which the molding space is partitioned, the right contact portion, which is part of the right auxiliary member, and the left contact portion, which is part of the left auxiliary member, are in contact with each other. During the first mold opening process, the right contact portion and the left contact portion remain in contact with each other. The manufacturing method according to claim 1, characterized in that it

3. In the state in which the molding space is partitioned, both the right contact portion, which is part of the right auxiliary member, and the left contact portion, which is part of the left auxiliary member, are in contact with the positioning stopper portion, which is provided independently of the right mold and the left mold. During the first type opening process, the right contact portion and the left contact portion remain in contact with the positioning stopper portion. The manufacturing method according to claim 1, characterized in that it

4. The aforementioned right-side auxiliary member is capable of protruding inward into the right-side cavity due to the biasing force of the elastic member. The aforementioned left auxiliary member is also capable of protruding inward into the left cavity due to the biasing force of the elastic member. The manufacturing method according to any one of claims 1 to 3.

5. The aforementioned clip portion has a projection for narrowing the gap on its back side, In the first type opening step, the gap-narrowing protrusion is held between the right auxiliary member and the left auxiliary member. The manufacturing method according to claim 1 to 3, characterized in that it is a feature of the method described above.

6. The aforementioned clip portion has a projection for narrowing the gap on its back side, In the first type opening step, the gap-narrowing protrusion is held between the right auxiliary member and the left auxiliary member. The manufacturing method according to feature 4.

7. A manufacturing apparatus for producing resin molded products including the clip portion of a writing instrument, A right-side mold having a right-side cavity corresponding to the right-side contour of the clip portion, A left-side mold having a left-side cavity corresponding to the left contour of the clip portion, A right auxiliary member, which constitutes a part of the inner surface on the cavity side that demarcates the right cavity of the right mold, and which is movable to protrude inward from the right cavity, A left-side auxiliary member that forms a part of the inner surface on the cavity side that demarcates the left-side cavity of the left-side mold, while being movable to protrude inward into the left-side cavity, Equipped with, The right mold and the left mold are moved so as to be adjacent to each other, thereby dividing the molding space by the right cavity and the left cavity, and are moved so as to be separated from each other, thereby opening up the molding space. When the molding space is opened, the right auxiliary member protrudes inward into the right cavity, and the left auxiliary member protrudes inward into the left cavity, so that the molded resin product is temporarily held between the right and left auxiliary members. A manufacturing apparatus characterized by the following features.

8. In the state in which the molding space is partitioned, the right contact portion, which is part of the right auxiliary member, and the left contact portion, which is part of the left auxiliary member, are in contact with each other. Even while the resin molded product is temporarily held between the right auxiliary member and the left auxiliary member, the right contact portion and the left contact portion remain in contact with each other. The manufacturing apparatus according to feature 7.

9. Positioning stopper portion provided independently of the right side mold and the left side mold Furthermore, In the state in which the molding space is partitioned, both the right contact portion, which is part of the right auxiliary member, and the left contact portion, which is part of the left auxiliary member, are in contact with the positioning stopper portion. Even while the resin molded product is temporarily held between the right auxiliary member and the left auxiliary member, the right contact portion and the left contact portion remain in contact with the positioning stopper portion. The manufacturing apparatus according to feature 7.

10. The aforementioned right-side auxiliary member is capable of protruding inward into the right-side cavity due to the biasing force of the elastic member. The aforementioned left auxiliary member is also capable of protruding inward into the left cavity due to the biasing force of the elastic member. The manufacturing apparatus according to any one of 7 to 9, characterized by the features described herein.

11. The aforementioned clip portion has a projection for narrowing the gap on its back side, When the molding space is opened, the state in which the gap-narrowing protrusion is temporarily held between the right auxiliary member and the left auxiliary member is maintained. The manufacturing apparatus according to claims 7 to 9, characterized by the features described herein.

12. The aforementioned clip portion has a projection for narrowing the gap on its back side, When the molding space is opened, the state in which the gap-narrowing protrusion is temporarily held between the right auxiliary member and the left auxiliary member is maintained. The manufacturing apparatus according to feature 10.

13. A resin molded product including the clip portion of a writing instrument, The aforementioned clip portion has a projection for narrowing the gap on its back side, Manufactured by the method of claim 5 A resin molded product characterized by the following features.

14. A resin molded product including the clip portion of a writing instrument, The aforementioned clip portion has a projection for narrowing the gap on its back side, On each of the left and right sides of the aforementioned gap-narrowing protrusion, pressure marks or contact marks with a depth of 0.005 mm to 0.3 mm are formed. A resin molded product characterized by the following features.

15. A writing instrument comprising a resin molded article as described in claim 13.

16. A writing instrument comprising the resin molded article described in Claim 14.

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