JP2020097189A - Method of manufacturing friction body of thermochromic writing instrument - Google Patents

Abstract

To provide a method of manufacturing a component of a writing instrument which solves such a problem that a resin molded article and an ejector member adhere to each other not to separate.SOLUTION: The method includes: a one side drawing out process of drawing out one side of a resin molded article from one side cavity of a metal mold; and an other side drawing out process of drawing out the other side of the resin molded article from the other cavity of the metal mold by transferring an ejector member. A locking part interfering with the part of the other cavity in an ejector-transferring direction is provided on a contour of the other side of the resin molded article at a position more the other side than a part of the other cavity. The locking part is protruded from a contour of the part of the other cavity viewing in an ejector-transferring direction. The other side drawing out process includes a process of passing through the inside of the other cavity while elastically deforming the locking part to form a crushed shape. The resin molded article and the ejector member separate from each other by a back action force of elastically returning to an original shape from the crushed shape right after releasing the locking part from the other cavity.SELECTED DRAWING: Figure 13

Description

The present invention relates to a method for manufacturing a friction body of a thermochromic writing instrument. Broadly, it relates to a method for producing a resin molded product. Further, the present invention relates to a writing instrument including a part manufactured by the manufacturing method.

2. Description of the Related Art As a writing instrument including a pen tip, ink, and an ink containing tube, products having various types of configurations have been developed and sold.

In recent years, thermochromic writing instruments that use thermochromic ink that can be erased by rubbing the handwriting after writing with a friction body have maintained a very good sales (product name "friction"). (Registered trademark)).

The applicant of the present application has obtained a patent that is characterized in that a friction body dedicated to a thermochromic writing instrument is attached to the rear portion of the writing instrument or the top of the cap (Japanese Patent No. 4312987).

FIG. 1 shows an example of a thermochromic writing instrument with a friction body dedicated to the thermochromic writing instrument mounted on the rear part. As shown in FIG. 1, the thermochromic writing instrument 100 includes a writing body 102, a tubular portion 103 for housing the writing body 102, a clip 104 slidably held in the tubular portion, and a tubular portion 103. And the held friction body 105. The writing body 102 includes a pen tip 101, an ink containing tube in which the pen tip 101 is press-fitted and fixed in a front end opening portion, a thermochromic ink filled in the ink containing tube, and a rear end of the thermochromic ink. And a follower (for example, a high-viscosity fluid) that is filled with the thermochromic ink and advances as the thermochromic ink is consumed. The pen tip 101 is configured to be retractable by utilizing sliding of the clip 104.

Japanese Patent No. 4312987 JP, 11-277545, A

The applicant of the present invention has come to understand the following problems regarding the production of the friction body dedicated to the thermochromic writing instrument.

The friction body 105 dedicated to the thermochromic writing instrument is manufactured from a resin material by an injection molding method. As shown in FIG. 2, the manufacturing apparatus includes a one-side cavity 501 having a one-side cavity 501c corresponding (complementarily) to the one-side (upper side in FIG. 2) contour of a friction body 105 which is a resin molded product, Two friction elements 105 having two tip shapes corresponding to the respective shapes of the two pressed elements 53 and 54 (collectively pressed parts) provided on a part of the other side (lower side of FIG. 2). The ejector elements 503 and 504 (collectively referred to as ejector portions) and the contours of the one-side cavity 501 adjacent to the one cavity 501c and the other side of the friction body 105 excluding the pressed elements 53 and 54 (complementarily) are supported. The other side cavity 502 having the other side cavity 502c.

In the example of FIG. 2, the one side cavity 501 is a fixed side cavity and the other side cavity 502 is a movable side cavity (moves in the axial direction of the ejector elements 503 and 504 with respect to the one side cavity 501).

Then, the resin material is injected into the molding space defined by the one cavity 501c of the one side cavity 501, the other cavity 502c of the other side cavity 502, and the tip shapes of the two ejector elements 503 and 504. The friction body 105 is molded (see FIG. 2).

After that, the molded friction body 105 must be taken out from the manufacturing apparatus. First, the one side cavity 501 and the other side cavity 502 are separated from each other, and the one cavity 501c and the other cavity 502c are separated from each other, so that the front portion of the friction body 105 is extracted from the one cavity 501c. .. At this time, a core pin (not shown) connected to the other side cavity 502 is inserted into the friction body 105 in the axial direction of the friction body 105. As a result, the friction body 105 remains in the other cavity 502c when the one side cavity 501 and the other side cavity 502 are separated from each other. After that, the core pin is pulled out.

Subsequently, the two ejector elements 503 and 504 are moved to one side with respect to the other side cavity 502, so that the other side of the friction body 105 is extracted from the other side cavity 502c (see FIG. 3).

Here, if the friction body 105 and the ejector elements 503 and 504 are separated after the other side of the friction body 105 is pulled out from the other cavity 502c, the friction body 105 falls below the manufacturing apparatus, that is, friction. The body 105 can be removed. However, the molded friction body 105 and the ejector elements 503 and 504 may adhere to each other, and the friction body 105 may not drop as desired.

As a mechanism for taking out the resin molded product adhered to the ejector elements 503 and 504 as described above, Patent Document 2 discloses that the resin molded product after being ejected is locked when the ejector member is returned to the other side. By doing so, it is proposed to employ an additional member called a stripper bush for separating the resin molded product and the ejector element. However, the adoption of such an additional member increases the cost of the manufacturing apparatus.

The present invention has been made in view of the above knowledge, and an object thereof is to solve the problem that the resin molded product and the ejector member do not adhere to each other and are not separated while suppressing an increase in cost. The present invention provides a method for producing a writing instrument part, which is broadly applicable, and a method for producing a resin molded article in general. Another object of the present invention is to provide a writing instrument including a component manufactured by the manufacturing method.

In order to manufacture a resin molded product, the present invention provides a cavity on one side having one cavity corresponding to the contour on one side of the resin molded product, and a pressed member provided on a part of the other side of the resin molded product. The ejector member having a tip shape corresponding to the shape of the portion, and the other cavity adjacent to the one cavity of the one side cavity and the other cavity corresponding to the contour of the other side of the resin molded product excluding the pressed portion A side cavity is used to inject a resin material into a molding space defined by the one cavity of the one cavity, the other cavity of the other cavity, and the tip shape of the ejector member. One side of the resin molded product by separating the one side cavity and the other side cavity from each other and the one cavity and the other cavity from each other. One side withdrawing step from the one side cavity, and by moving the ejector member to one side with respect to the other side cavity to press the pressed portion of the resin molded product to one side, the resin A method of manufacturing a resin molded product, the other side extracting process of extracting the other side of the molded product from the other cavity, wherein the other side of the other side cavity is on the contour of the other side of the resin molded product. At a position on the other side with respect to a part of the cavity, a locking part that interferes with the part of the other cavity of the other side cavity in the moving direction of the ejector is provided, and the locking part, When viewed in the moving direction of the ejector, it protrudes from the contour of the part of the other cavity of the other side cavity, and in the other side extracting step, the locking portion is elastically deformed to have a crushed shape, and The method is characterized by including a step of passing the inside of the other cavity of the other side cavity.

According to the method of the present invention, on the contour of the other side of the resin molded product, at the position on the other side of the other cavity of the other side cavity, the part of the other cavity interferes with the moving direction of the ejector. It is possible to pass the inside of the other cavity of the other side cavity while elastically deforming the relevant locking portion into a crushed shape in the other side extraction step by providing the locking portion.

Accordingly, the resin molded product and the ejector member can be separated by the reaction force that elastically returns from the crushed shape to the original shape immediately after the locking portion is released from the part of the other cavity. .. That is, the other side extraction step, by the reaction force that elastically returns from the collapsed shape to the original shape immediately after the locking portion is released from the part of the other cavity of the other side cavity, The method may include a step of separating the resin molded product and the ejector member.

Alternatively, even if the resin molded product and the ejector member cannot be separated by such a reaction force, the ejector return that moves the ejector member to the other side with respect to the other side cavity after the other side extraction process By carrying out the steps, the resin molded product and the ejector member can be separated. This is because in the ejector returning step, the locking portion that has returned to the original shape effectively prevents the resin molded product from returning to the other cavity. That is, it is possible to further include an ejector returning step of moving the ejector member to the other side with respect to the other side cavity after the other side extracting step, and the ejector returning step is performed by the ejector returning step. A step of separating the resin molded product and the ejector member by preventing the resin molded product from returning into the other cavity by the stopper can be included.

The locking portion is preferably formed in a dome shape, for example. In this case, it is easy to elastically deform the locking portion into a crushed shape in the other side extraction process. In addition, the amount of resin additionally required for manufacturing the resin molded product can be small, and the effect of suppressing damage to the resin molded product due to the occurrence of local stress concentration can be obtained.

Alternatively, the part of the other cavity of the other side cavity may be a protrusion projecting inward, and the locking part may be a part adjacent to the recess formed by the protrusion. In this case, a smaller amount of resin is required to manufacture the resin molded product. The recess of the resin molded product formed by the protrusion may be groove-shaped, for example. In this case, in order to facilitate elastically deforming the locking portion into a crushed shape, the surface of the groove-shaped concave portion on the locking portion side (complementarily to the locking portion side of the protrusion of the other cavity). More preferably, the surface) is inclined or curved with respect to the moving direction of the ejector.

Further, it is preferable that the pressed portion has a plurality of pressed elements, and the ejector member has a plurality of ejector elements each having a tip shape corresponding to the shape of the corresponding pressed element. In this case, the other side extraction process can be performed more stably.

The resin molded article to be produced by the method of the present invention is intended to be a friction body of a thermochromic writing instrument, but it is not limited to a writing instrument component at least at the time of the present application.

Further, the present invention is a thermochromic writing instrument having a friction body produced by the method of the present invention. In particular, the present invention comprises a cursive body, a cylindrical portion that accommodates the cursive body, and a friction member made of resin held by the cylindrical portion, wherein the cursive body includes at least a pen tip and the pen tip. And a thermochromic ink filled in the ink containing tube, and a dome-shaped ridge is provided on a side surface of the friction body. It is a sex writing instrument.

According to the method of the present invention, since the dome-shaped raised portion is provided on the side surface of the friction body and the raised portion can be temporarily collapsed due to elastic deformation, the friction body is ejected. When manufacturing by the molding method, in the step of extracting the other side of the friction body from the other cavity of the other side cavity which is the injection mold using the ejector member, while elastically deforming the dome-shaped raised portion to make it a crushed shape It can be passed through the rear cavity.

Thus, the friction body and the ejector member can be separated by the reaction force that elastically returns from the collapsed shape to the raised shape immediately after the raised portion is released from the other cavity. Alternatively, even if the friction body and the ejector member cannot be separated by such a reaction force, after the step of extracting the other side of the friction body, the ejector member is moved to the other side with respect to the other side cavity. By performing the ejector returning step, the friction body and the ejector member can be separated. This is because, in the ejector returning step, the raised portion that has returned to the raised shape effectively prevents the friction body from returning to the other cavity.

Alternatively, the present invention includes a cursive body, a cylinder portion that accommodates the cursive body, and a resin friction body held by the cylinder portion, and the cursive body includes at least a pen tip and the pen tip. Is fixed to the ink containing tube, and the thermochromic ink filled in the ink containing tube, the side surface of the friction member is provided with a groove extending in the axial direction, the cross section of the groove, A thermochromic writing instrument characterized in that at least one side is inclined or curved.

According to the method of the present invention, the side surface of the friction body is provided with the groove extending in the axial direction, and the portion adjacent to the groove is the locking portion for the protrusion of the other cavity of the other cavity for molding the groove. Therefore, when the friction body is manufactured by the injection molding method, the other cavity of the other side cavity which is the injection molding die using the ejector member is used. In the step of extracting the other side of the friction body from the above, the engaging portion can be elastically deformed by the projection of the other cavity of the other side cavity to pass through the rear cavity while having a crushed shape. In particular, if the surface of the groove on the side of the locking portion (complementarily the surface on the locking portion side of the protrusion of the other cavity) is inclined or curved with respect to the moving direction of the ejector, the locking portion is elastically deformed. It is preferable because it can be easily made into a crushed shape.

Thus, the friction body and the ejector member can be separated by the reaction force that elastically returns from the crushed shape to the original shape immediately after the locking portion is released from the protrusion of the other cavity. Alternatively, even if the friction body and the ejector member cannot be separated by such a reaction force, after the step of extracting the other side of the friction body, the ejector member is moved to the other side with respect to the other side cavity. By performing the ejector returning step, the friction body and the ejector member can be separated. This is because in the ejector returning step, the locking portion that has returned to the original shape effectively prevents the friction body from returning to the other cavity.

According to the method of the present invention, on the contour of the other side of the resin molded product, at the position on the other side of the other cavity of the other side cavity, the part of the other cavity interferes with the moving direction of the ejector. It is possible to pass the inside of the other cavity of the other side cavity while elastically deforming the relevant locking portion into a crushed shape in the other side extraction step by providing the locking portion.

Accordingly, the resin molded product and the ejector member can be separated by the reaction force that elastically returns from the crushed shape to the original shape immediately after the locking portion is released from the part of the other cavity. .. That is, the other side extraction step, by the reaction force that elastically returns from the collapsed shape to the original shape immediately after the locking portion is released from the part of the other cavity of the other side cavity, The method may include a step of separating the resin molded product and the ejector member.

Alternatively, even if the resin molded product and the ejector member cannot be separated by such a reaction force, the ejector return that moves the ejector member to the other side with respect to the other side cavity after the other side extraction process By carrying out the steps, the resin molded product and the ejector member can be separated. This is because in the ejector returning step, the locking portion that has returned to the original shape effectively prevents the resin molded product from returning to the other cavity. That is, it is possible to further include an ejector returning step of moving the ejector member to the other side with respect to the other side cavity after the other side extracting step, and the ejector returning step is performed by the ejector returning step. A step of separating the resin molded product and the ejector member by preventing the resin molded product from returning into the other cavity by the stopper can be included.

It is a schematic diagram of a general thermochromic writing instrument. It is the schematic of the manufacturing apparatus which manufactures the friction body of FIG. FIG. 5 is a schematic diagram for explaining a second-side extraction step of the manufacturing method for manufacturing the friction body of FIG. 2. It is a schematic diagram of a thermochromic writing instrument in a 1st embodiment of the present invention. FIG. 3 is a front view of the friction body according to the first embodiment of the present invention. It is the sectional view on the AA line of the friction body of FIG. It is a B section enlarged view of the friction body of FIG. FIG. 8 is a perspective view of the friction body of FIGS. 5 to 7. FIG. 9 is a schematic view of a manufacturing apparatus for manufacturing the friction body of FIGS. 5 to 8 in which a cavity corresponding to the friction body is viewed in the axial direction. It is a schematic diagram for explaining the injection molding process of the manufacturing method which manufactures the friction body of Drawing 5 thru/or Drawing 8. It is a schematic diagram for explaining the front part extraction process of the manufacturing method which manufactures the friction body of Drawing 5 thru/or Drawing 8. FIG. 9 is a schematic view for explaining a rear part extracting step of the manufacturing method for manufacturing the friction body of FIGS. 5 to 8. It is a schematic diagram for explaining the ejector return process of the manufacturing method which manufactures the friction body of Drawing 5 thru/or Drawing 8. It is a schematic diagram for explaining the ejector return process of the manufacturing method which manufactures the friction body of Drawing 5 thru/or Drawing 8. It is a schematic diagram for explaining the ejector re-extrusion process of the manufacturing method which manufactures the friction body of Drawing 5 thru/or Drawing 8. FIG. 9 is a schematic diagram for explaining an ejector returning step of the manufacturing method for manufacturing the friction body of FIGS. 5 to 8. It is a schematic diagram of a thermochromic writing instrument in a 2nd embodiment of the present invention. It is a front view of a friction body in a 2nd embodiment of the present invention. It is the sectional view on the AA line of the friction body of FIG. It is a B section enlarged view of the friction body of FIG. FIG. 21 is a perspective view of the friction body of FIGS. 18 to 20. FIG. 22 is a schematic view of a manufacturing apparatus for manufacturing the friction body of FIGS. 18 to 21 in which a cavity corresponding to the friction body is viewed in the axial direction. FIG. 22 is a schematic diagram for explaining an injection molding process of a manufacturing method for manufacturing the friction body of FIGS. 18 to 21. It is a schematic diagram for explaining the front part extraction process of the manufacturing method which manufactures the friction body of Drawing 18 thru/or Drawing 21. FIG. 22 is a schematic diagram for explaining a rear part extracting step of the manufacturing method for manufacturing the friction body of FIGS. 18 to 21. FIG. 22 is a schematic diagram for explaining an ejector returning step of the manufacturing method for manufacturing the friction body of FIGS. 18 to 21. FIG. 22 is a schematic diagram for explaining an ejector returning step of the manufacturing method for manufacturing the friction body of FIGS. 18 to 21. FIG. 22 is a schematic diagram for explaining an ejector re-extrusion step of the manufacturing method for manufacturing the friction body of FIGS. 18 to 21. FIG. 22 is a schematic diagram for explaining an ejector returning step of the manufacturing method for manufacturing the friction body of FIGS. 18 to 21.

(Configuration of First Embodiment of Thermochromic Writing Tool)
First, a first embodiment of a thermochromic writing instrument having a friction body manufactured by the method of the present invention will be described. FIG. 4 is a schematic diagram of the thermochromic writing instrument 10 in this embodiment. As shown in FIG. 4, the thermochromic writing instrument 10 includes a writing body 12, a cylinder portion 13 for accommodating the writing body 12, a clip 14 slidably held in the cylinder portion, and a cylindrical portion 13. The held friction body 15 is provided. The writing body 12 includes a pen tip 11, an ink containing tube in which the pen tip 11 is press-fitted and fixed in a front end opening, a thermochromic ink filled in the ink containing tube, and a rear end of the thermochromic ink. And a follower (for example, a high-viscosity fluid) that is filled with the thermochromic ink and advances as the thermochromic ink is consumed. The pen tip 11 is configured to be retractable by utilizing sliding of the clip 14.

5 is a front view of the friction body 15 in the present embodiment, FIG. 6 is a cross-sectional view taken along the line AA of the friction body 15 of FIG. 5, and FIG. 7 is a B portion of the friction body 15 of FIG. FIG. 8 is an enlarged view, and FIG. 8 is a perspective view of the friction body 15 of FIGS. 5 to 7.

As shown in FIGS. 5 to 8, the friction body 15 includes, from the upper end side, a dome-shaped portion 15a, a first frusto-conical portion 15b that gradually spreads downward, a cylindrical first connecting portion 15c, and a downward side. It has a narrowed second frusto-conical portion 15d, a cylindrical second connecting portion 15e, a downwardly narrowed third frusto-conical portion 15f, and a cylindrical small diameter portion 15g, and the first frusto-conical portion 15b. A step S1 is formed between the first connection portion 15c and the first connection portion 15c, and a step S2 is formed between the second connection portion 15e and the third truncated cone portion 15f, but the other portions are adjacent to each other. The elements are transitioning smoothly (continuously).

For example, the dome-shaped portion 15a has a length of 2.3 mm, the first truncated conical portion 15b has a length of 4.5 mm, and the first connection portion 15c has a length of 0.8 mm. Yes, the second truncated cone portion 15d is 0.4 mm, the second connection portion 15e is 0.8 mm, the third truncated cone portion 15f is 2.2 mm, and the small diameter portion 15g is 2.8 mm. Yes, the diameter is 5.4 mm at the lower end of the dome-shaped portion 15a and the upper end of the first truncated conical portion 15b, 6.0 mm at the lower end of the first truncated conical portion 15b, and at the first connection portion 15c. 5.2 mm, 4.6 mm at the second connecting portion 15e, 5.6 mm at the upper end of the third truncated conical portion 15f, and 4 at the lower end of the third truncated conical portion 15f and the small diameter portion 15g. It is 0.4 mm.

Further, on the side surface of the small diameter portion 15g, a flat portion 153 corresponding to a flat tip shape of a first ejector element 303 described later is formed as a first pressed element. The flat portion 153 is configured to form a flat surface having a distance d3=1.9 mm from the axial center C of the friction body 15 in the range from the lower end of the small diameter portion 15g to the axial length 2.5 mm, for example. There is.

Further, on the side surface of the first connection portion 15c and the side surface of the second truncated cone portion 15d, a flat portion 154 corresponding to a flat tip shape of a second ejector element 304 described later is formed as a second pressed element. ing. The flat portion 154 is configured to form, for example, a flat surface having a distance d4=2.4 mm from the axis C of the friction body 15.

A dome-shaped raised portion 151 is formed on the side surface of the small diameter portion 15g. The raised portion 151 of the present embodiment is configured as a part of a spherical surface having a radius of 0.7 mm, and the distance of the maximum raised portion (apex) from the axis C of the friction body 15 is 2.6 mm. The distance between the maximum ridge and the extension plane of the flat portion 153 is 0.9 mm, and the axial distance from the lower end of the small diameter portion 15g of the maximum ridge is 1.5 mm.

However, the arrangement and shape of the dome-shaped raised portion 151 are such that the pressed element (flat portion 153) in the moving direction of the ejector elements 303 and 304 (a direction perpendicular to the flat portions 153 and 154 in this embodiment) described later. 154), the end 151f on the side farther from the end is inclined or curved at a shallower angle, and the end 151n on the side closer to the pressed element (flat portion 153, 154) is inclined at a deeper angle (including a right angle). ) Or curved, any arrangement and shape can be adopted.

(Method for manufacturing the friction body 15)
The present invention is a method for producing a resin molded product that solves the problem that the resin molded product and the ejector member do not adhere to each other and do not separate without adding a configuration such as a stripper bush (that is, while suppressing an increase in cost). .. As one embodiment of the invention, a method for manufacturing the friction body 15 of the thermochromic writing instrument 10 described above as a resin molded product will be described.

The friction body 15 is manufactured from a resin material (for example, a thermoplastic elastomer) by an injection molding method. The resin material forming the friction body 15 is preferably a synthetic resin having elasticity (rubber, elastomer) such as silicone resin, SBS resin (styrene-butadiene-styrene copolymer), SEBS resin (styrene-ethylene-butylene). -Styrene copolymer), fluororesin, chloroprene resin, nitrile resin, polyester resin, ethylene propylene diene rubber (EPDM) or a mixture of two or more rubber elastic materials, and a mixture of a rubber elastic material and a synthetic resin. Etc. The elastic synthetic resin forming the friction body 15 is not a highly wear-resistant elastic material (for example, an eraser), but a low-wearing elastic material that hardly causes wear debris (erasing debris) during friction. As shown in FIG. 9, the manufacturing apparatus includes a one-side cavity 301 having a one-side cavity 301c corresponding (complementarily) to the one-side (upper side in FIG. 9) contour of the friction body 15 which is a resin molded product, Two parts having a tip shape corresponding to the respective shapes of the two pressed elements 153, 154 (collectively pressed parts) provided on a part of the other side (lower side in FIG. 9) of the friction body 15 are provided. The ejector elements 303 and 304 (collectively referred to as ejector portions) and the contours of the one-side cavity 301 adjacent to the one cavity 301c and corresponding to the contours of the friction body 15 excluding the pressed elements 153 and 154 on the other side (complementarily) are supported. The other side cavity 302c having the other side cavity 302c (including the concave portion 302r corresponding to the raised portion 151).

In the example of FIG. 9, the one side cavity 301 is a fixed side cavity and the other side cavity 302 is a movable side cavity (moves in the axial direction of the ejector elements 303 and 304 with respect to the one side cavity 301).

Then, the resin material is injected into the molding space defined by the one cavity 301c of the one side cavity 301, the other cavity 302c of the other side cavity 302, and the tip shapes of the two ejector elements 303 and 304. The friction body 15 is molded (injection molding process: see FIG. 10).

After that, the molded friction body 15 must be taken out of the manufacturing apparatus. First, the one side cavity 301 and the other side cavity 302 are separated from each other, and the one cavity 301c and the other cavity 302c are separated from each other, so that one side of the friction body 15 is extracted from the one cavity 301c ( One side extraction step: see FIG. 11.). At this time, a core pin (not shown) connected to the other side cavity 302 is inserted into the friction body 15 in the axial direction of the friction body 15. As a result, the friction body 15 remains in the other cavity 302c when the one side cavity 301 and the other side cavity 302 are separated from each other. After that, the core pin is pulled out.

Subsequently, the two ejector elements 303 and 304 are moved to the one side with respect to the other side cavity 302, so that the other side of the friction body 15 is extracted from the other side cavity 302c (the other side extracting step).

As described above, the dome-shaped raised portion 151 is formed on the side surface of the small diameter portion 15g of the friction body 15. The raised portion 151 is a wall surface that defines the other cavity 302c of the other cavity 302 that is an injection mold during the extraction process on the other side by the ejector elements 303 and 304 (on the one side of the raised portion 151 of the other cavity 302c. It is elastically deformed by a part (may be accompanied by a slight plastic deformation) and temporarily becomes a collapsed shape (while passing through the wall surface). Accordingly, the other side extraction process by the ejector elements 303 and 304 can be performed regardless of the presence of the raised portion 151.

Then, in the present embodiment, the friction body 15 and the ejector elements 303, 304 are caused to react with each other by the reaction force generated when the raised portion 151 is elastically returned from the crushed shape to the raised shape immediately after being released from the other cavity 302c. Can be separated. As a result, many of the molded friction bodies 15 separate from the ejector elements 303 and 304 and drop during the other side extraction process.

However, about 5 to 10% of the friction body 15 is not separated from the ejector elements 303 and 304 even by the reaction force described above (see FIG. 12). In such a case, the ejector elements 303 and 304 are returned to the other side of the other side cavity 302 (ejector returning step).

At this time, the raised portion 151 that has returned to the raised shape effectively prevents the friction body 15 from returning into the other cavity 302c (see FIG. 13), and the friction body 15 and the ejector elements 303 and 304 are separated. As a result, most of the friction bodies 15 that have not been separated from the ejector elements 303 and 304 due to the reaction force described above separate and drop from the ejector elements 303 and 304 during the ejector returning step.

Here, further, there is a case in which the friction body 15 still does not fall due to a part of the friction body 15 being caught in the other cavity 302c (see FIG. 14). In such a case, the ejector elements 303 and 304 are moved to the one side again with respect to the cavity 302 on the other side (ejector re-extrusion step: see FIG. 15 ). As a result, the friction body 15 that has been caught in the other cavity 302c and has not fallen is pushed and dropped by the ejector elements 303 and 304 in the ejector re-pushing step.

Then, the ejector elements 303 and 304 are returned to the other side of the other side cavity 302 again (ejector re-returning step: see FIG. 16 ).

(Advantages of Manufacturing Method of Friction Body 15)
According to the manufacturing method as described above, when the friction body 15 is manufactured by the injection molding method, the ejector elements 303 and 304 are used to remove the other side of the friction body 15 from the other cavity 302c of the other side cavity 302 which is an injection mold. In the step of extracting the side, the raised portion 151 is elastically deformed into a crushed shape so that the raised portion 151 can pass through the other cavity 302c.

Then, the friction body 15 and the ejector elements 303 and 304 can be separated by the reaction force that elastically returns from the crushed shape to the raised shape immediately after the raised portion 151 is released from the other cavity 302c.

Alternatively, even when the friction body 15 and the ejector elements 303 and 304 cannot be separated by such a reaction force, after the step of extracting the other side of the friction body 15 is performed, the ejector is not attached to the cavity 302 on the other side. By performing the ejector returning step of moving the elements 303 and 304 to the other side, the friction body 15 and the ejector elements 303 and 304 can be separated. This is because, in the ejector returning step, the raised portion 151 that has returned to the raised shape effectively prevents the friction body 15 from returning to the inside of the other cavity 302c.

Further, even when the friction body 15 separated from the ejector elements 303, 304 is not dropped due to being caught in the other cavity 302c in the ejector returning step, the friction body 15 is not ejected in the subsequent ejector re-extruding step. It can be pushed by 304 and fall.

Further, in the present embodiment, the end portion 151f of the raised portion 151 on the side far from the pressed element (flat portion 153, 154) of the friction body 15 pushed by the ejector element 303, 304 is in the moving direction of the ejector element 303, 304. Since it is inclined or curved at a shallower angle, it is easy to elastically deform the raised portion 151 into a crushed shape in the other side extraction process.

On the other hand, the end portion 151n of the raised portion 151 on the side closer to the pressed element (flat portion 153, 154) of the friction body 15 pushed by the ejector elements 303, 304 is deeper in the moving direction of the ejector elements 303, 304. Since it is inclined or curved at an angle, the raised portion 151 that has returned to the raised shape is likely to interfere with the end surface of the other side cavity 302 during the ejector return step, that is, the friction body 15 returns to the other side cavity 302c. The effect of hindering is enhanced.

Further, in the present embodiment, by using the two ejector elements 303 and 304 having the tip shapes corresponding to the two flat portions 153 and 154 as the pressed elements, the other-side extraction process is performed more stably. be able to.

(Structure of the second embodiment of the thermochromic writing instrument)
First, a second embodiment of the thermochromic writing instrument having a friction body manufactured by the method of the present invention will be described. FIG. 17 is a schematic view of the thermochromic writing instrument 20 in this embodiment. As shown in FIG. 17, the thermochromic writing instrument 20 is also slidable on the writing instrument 22, the tubular portion 23 that accommodates the writing instrument 22, and the tubular portion, similar to the thermochromic writing instrument 10 described above. The clip 24 held and the friction body 25 held by the tubular portion 23 are provided. The writing body 22 includes a pen tip 21, an ink containing tube in which the pen tip 21 is press-fitted and fixed to a front end opening portion, a thermochromic ink filled in the ink containing tube, and a rear end of the thermochromic ink. And a follower (for example, a high-viscosity fluid) that is filled with the thermochromic ink and advances as the thermochromic ink is consumed. The pen tip 21 is configured to be retractable by utilizing sliding of the clip 24.

18 is a front view of the friction body 25 according to the present embodiment, FIG. 19 is a sectional view taken along the line AA of the friction body 25 of FIG. 18, and FIG. 20 is a portion B of the friction body 25 of FIG. FIG. 21 is an enlarged view, and FIG. 21 is a perspective view of the friction body 25 of FIGS. 18 to 20.

As shown in FIGS. 18 to 21, the friction body 25 also includes a dome-shaped portion 25a, a first frusto-conical portion 25b that gradually spreads downward, a cylindrical first connecting portion 25c, and a friction member 25 from the upper end side to the lower side. It has a narrowed second frustoconical portion 25d, a cylindrical second connecting portion 25e, a downwardly narrowed third frustoconical portion 25f, and a cylindrical small diameter portion 25g, and the first frustoconical portion 25b. A step S1 is formed between the first connecting portion 25c and the first connecting portion 25c, and a step S2 is formed between the second connecting portion 25e and the third frusto-conical portion 25f. The elements are transitioning smoothly (continuously).

For example, the dome-shaped portion 25a has a length of 2.3 mm, the first truncated conical portion 25b has a length of 4.5 mm, and the first connection portion 25c has a length of 0.8 mm. Yes, the second truncated cone 25d is 0.4 mm, the second connecting portion 25e is 0.8 mm, the third truncated cone 25f is 2.2 mm, and the small diameter portion 25g is 2.8 mm. The diameter is 5.4 mm at the lower end of the dome-shaped portion 25a and the upper end of the first truncated conical portion 25b, 6.0 mm at the lower end of the first truncated conical portion 25b, and at the first connecting portion 25c. 5.2 mm, 4.6 mm at the second connecting portion 25e, 5.6 mm at the upper end of the third truncated conical portion 25f, and 4 at the lower end of the third truncated conical portion 25f and the small diameter portion 25g. It is 0.4 mm.

Further, on the side surface of the small diameter portion 25g, a flat portion 253 corresponding to a flat tip shape of a first ejector element 403 described later is formed as a first pressed element. The flat portion 253 is configured to form a flat surface having a distance d3=1.9 mm from the axial center C of the friction body 25 in the range from the lower end of the small diameter portion 25g to the axial length 2.5 mm, for example. There is.

Further, a flat portion 254 corresponding to a flat tip shape of a second ejector element 404 described later is formed as a second pressed element on the side surface of the first connecting portion 25c and the side surface of the second truncated cone portion 25d. ing. The flat portion 254 is configured to form, for example, a flat surface having a distance d4=2.4 mm from the axis C of the friction body 25.

A groove-shaped recess 252 is formed on the side surface of the small diameter portion 25g. With reference to FIG. 19 and FIG. 20 in particular, the groove-shaped recess 252 has a flat wall surface 252 a (depth 0.5 mm) parallel to the flat portion 253 located on the side far from the flat portion 253, and a radius of curvature of 0. And a cylindrical surface 252b of 0.5 mm. A portion of the friction body 25 adjacent to the cylindrical surface 252b constitutes a locking portion 251.

The arrangement and shape of the groove-shaped recess 252 are such that the pressed element (flat part) of the recess 252 is relative to the moving direction of ejector elements 403 and 404 (directions perpendicular to the flat parts 253 and 254 in this embodiment) described later. If the locking portion 251 adjacent to the (253, 254) side is inclined or curved, any arrangement and shape can be adopted.

(Method for manufacturing friction body 25)
The present invention is a method for producing a resin molded product that solves the problem that the resin molded product and the ejector member do not adhere to each other and do not separate without adding a configuration such as a stripper bush (that is, while suppressing an increase in cost). .. As one embodiment of the invention, a method of manufacturing the friction body 25 of the thermochromic writing instrument 20 described above as a resin molded product will be described.

The friction body 25 is manufactured from a resin material (for example, a thermoplastic elastomer) by an injection molding method. The resin material forming the friction body 25 is preferably an elastic synthetic resin (rubber, elastomer), such as silicone resin, SBS resin (styrene-butadiene-styrene copolymer), SEBS resin (styrene-ethylene-butylene). -Styrene copolymer), fluororesin, chloroprene resin, nitrile resin, polyester resin, ethylene propylene diene rubber (EPDM) or a mixture of two or more rubber elastic materials, and a mixture of a rubber elastic material and a synthetic resin. Etc. The elastic synthetic resin forming the friction body 25 is not a highly wear-resistant elastic material (for example, an eraser), but a low-wearing elastic material that hardly causes wear debris (erased dust) during friction. As shown in FIG. 22, the manufacturing apparatus includes a one-side cavity 401 having a one-side cavity 401c corresponding (complementarily) to the contour of one side (upper side in FIG. 22) of the friction body 25 which is a resin molded product, Two two pressed elements 253, 254 (generally called pressed portions) provided on a part of the other side (lower side in FIG. 22) of the friction body 25 have tip shapes corresponding to the respective shapes. It corresponds (complementarily) to the ejector elements 403 and 404 (collectively referred to as ejector portions) and the contours of the one-side cavity 401 that is adjacent to the one cavity 401c and excludes the pressed elements 253 and 254 on the other side of the friction body 25. And the other side cavity 402 having the other side cavity 402c.

In the example of FIG. 22, the one side cavity 401 is a fixed side cavity and the other side cavity 402 is a movable side cavity (moves in the axial direction of the ejector elements 403 and 404 with respect to the one side cavity 401).

Then, the resin material is injected into the molding space defined by the one cavity 401c of the one side cavity 401, the other cavity 402c of the other side cavity 402, and the tip shapes of the two ejector elements 403 and 404. The friction body 25 is molded (injection molding process: see FIG. 23).

After that, the molded friction body 25 must be taken out from the manufacturing apparatus. First, the one side cavity 401 and the other side cavity 402 are separated from each other, and the one cavity 401c and the other cavity 402c are separated from each other, so that one side of the friction body 25 is extracted from the one cavity 401c ( One side extraction step: see FIG. 24). At this time, a core pin (not shown) connected to the other-side cavity 402 is inserted into the friction body 25 in the axial direction of the friction body 25. As a result, the friction body 25 remains in the other cavity 402c when the one side cavity 401 and the other side cavity 402 are separated from each other. After that, the core pin is pulled out.

Subsequently, the two ejector elements 403 and 404 are moved to one side with respect to the other side cavity 402, so that the other side of the friction body 25 is extracted from the other cavity 402c (the other side extraction step).

As described above, the groove-shaped recess 252 is formed on the side surface of the small diameter portion 25g of the friction body 25, and the protrusion 402p is provided in the other cavity 402c corresponding to the recess 252. Then, the locking portion 251 adjacent to the groove-shaped recess 252 defines the wall surface (the other cavity) that defines the other cavity 402c of the other cavity 402 that is an injection mold during the other side extraction process by the ejector elements 403 and 404. It is elastically deformed by the protrusion 402p of 402c (may be accompanied by a slight plastic deformation) and becomes a crushed shape temporarily (while passing through the wall surface). As a result, the ejecting elements 403 and 404 perform the other-side extraction process even though the locking portion 251 of the friction body 25 and the protrusion 402p of the other cavity 402c interfere with the moving direction of the ejector elements 403 and 404. be able to.

Then, in the present embodiment, the frictional body 25 and the friction body 25 are generated by the reaction force generated when the locking portion 251 is elastically returned from the collapsed shape to the original shape immediately after being released from the protrusion 402p of the other cavity 402c. The ejector elements 403, 404 can be separated. As a result, many of the molded friction bodies 25 separate from the ejector elements 403 and 404 and fall during the other side extraction process.

However, about 5 to 10% of the friction body 25 is not separated from the ejector elements 403 and 404 even by the reaction force described above (see FIG. 25). In such a case, the ejector elements 403 and 404 are returned to the other side with respect to the other side cavity 402 (ejector returning step).

At this time, the locking portion 251 that has returned to the original shape effectively prevents the friction body 25 from returning into the other cavity 402c (see FIG. 26), and the friction body 25 and the ejector elements 403 and 404 are separated. It As a result, most of the friction bodies 25 that have not been separated from the ejector elements 403 and 404 even by the reaction force described above separate and drop from the ejector elements 403 and 404 during the ejector returning step.

Here, further, there is a case in which the friction body 25 still does not fall due to a part of the friction body 25 being caught in the other cavity 402c (see FIG. 27). In such a case, the ejector elements 403 and 404 are moved to the one side again with respect to the other side cavity 402 (ejector re-extrusion step: see FIG. 28). As a result, the friction body 25 that has been caught in the other cavity 402c and has not fallen is pushed by the ejector elements 403 and 404 and falls by the ejector re-extruding step.

Then, the ejector elements 403 and 404 are returned to the other side of the other side cavity 402 again (ejector re-returning step: see FIG. 29).

(Advantages of Method of Manufacturing Friction Body 25)
According to the manufacturing method as described above, when the friction body 25 is manufactured by the injection molding method, the ejector elements 403 and 404 are used to remove the other side of the friction body 25 from the other cavity 402c of the other side cavity 402 which is an injection molding die. In the step of extracting the side, the locking portion 251 is elastically deformed to have a crushed shape so that the locking portion 251 can pass through the inside of the other cavity 402c.

Then, the friction body 25 and the ejector elements 403 and 404 are separated by the reaction force that elastically returns from the crushed shape to the original shape immediately after the locking portion 251 is released from the protrusion 402p of the other cavity 402c. Can be made.

Alternatively, even when the friction body 25 and the ejector elements 403 and 404 cannot be separated by such a reaction force, after the step of extracting the other side of the friction body 25, the ejector is ejected to the other side cavity 402. By performing the ejector returning step of moving the elements 403 and 404 to the other side, the friction body 25 and the ejector elements 403 and 404 can be separated. This is because, in the ejector returning step, the locking portion 251 that has returned to the original shape effectively prevents the friction body 25 from returning to the inside of the other cavity 402c.

Further, even when the friction body 25 separated from the ejector elements 403 and 404 does not drop due to being caught in the other cavity 402c in the ejector returning step, the friction body 25 is not ejected in the subsequent ejector re-extruding step. It can be pushed by 404 and fall.

Further, in the present embodiment, the surface of the groove-shaped recess 252 on the pressed element (flat portion 253, 254) side (that is, the surface of the locking portion 251 defined by the surface) is the moving direction of the ejector elements 303, 304. Since it is inclined or curved with respect to, it is easy to elastically deform the locking portion 251 into a crushed shape in the other side extraction process.

Also in this embodiment, by using the two ejector elements 403 and 404 having the tip shapes corresponding to the two flat portions 253 and 254 as the pressed elements, the other side extraction process is performed more stably. be able to.

10, 20, 100 Thermochromic writing instruments 11, 21, 101 Nibs 12, 22, 102 Writing bodies 13, 23, 103 Cylindrical portions 14, 24, 104 Clips 15, 25, 105 Friction bodies 15a, 25a Dome-shaped portion 15b , 25b First frustoconical portion 15c, 25c First connecting portion 15d, 25d Second frustoconical portion 15e, 25e Second connecting portion 15f, 25f Third frustoconical portion 15g, 25g Small diameter portion 53, 54 Pressed Element 151 Raised part 151f End 151n farther from the pressed element End end 153 closer to the pressed element Flat part (pressed element)
154 Flat part (pressed element)
251 Locking part 252 Recess (groove shape)
252a Flat wall surface 252b Cylindrical surface 253 Flat portion (pressed element)
254 Flat part (pressed element)
301, 401 One side cavity 301c, 401c One side cavity 302, 402 Other side cavity 302c, 402c Other side cavity 302r Recess 402p Projection 303, 403 First ejector element 304, 404 Second ejector element 501 One side cavity 501c One side cavity 502 Other side Side cavity 502c Other cavity 503 Ejector element 504 Ejector element C Axial center S1 Step S2 Step S2

Claims (9)

In order to manufacture resin molded products,
One side cavity having one cavity corresponding to the contour of one side of the resin molded product,
An ejector member having a tip shape corresponding to the shape of the pressed portion provided on the other side of the resin molded product,
Another cavity adjacent to the one cavity of the one side cavity and having the other cavity corresponding to the contour of the other side of the resin molded product excluding the pressed portion,
Using,
A resin material is injected into a molding space defined by the one cavity of the one side cavity, the other cavity of the other side cavity, and the tip shape of the ejector member to mold the resin molded product. Process,
One side extraction step of extracting one side of the resin molded product from the one cavity by separating the one side cavity and the other side cavity from each other and separating the one cavity and the other cavity from each other. When,
By moving the ejector member to one side with respect to the other side cavity and pressing the pressed portion of the resin molded product to one side, the other side of the resin molded product is extracted from the other cavity to the other side. Withdrawal process,
A method of manufacturing a resin molded article comprising:
On the contour of the other side of the resin molded product, at a position on the other side with respect to a part of the other cavity of the other side cavity, the part of the other cavity of the other side cavity and the ejector A locking part that interferes in the moving direction is provided,
The locking portion, when viewed in the moving direction of the ejector, protrudes from the contour of the part of the other cavity of the other cavity,
The method of extracting the other side includes a step of elastically deforming the locking portion to have a crushed shape and passing the inside of the other side cavity of the other side cavity. In the step of extracting the other side, immediately after the locking portion is released from the part of the other cavity of the other side cavity, the resin is elastically restored from the collapsed shape to the original shape by the reaction force. The method of claim 1, including the step of separating a molded article and the ejector member. After the other side extraction step, further comprising an ejector returning step of moving the ejector member to the other side with respect to the other side cavity,
The ejector returning step includes a step of separating the resin molded product and the ejector member by preventing the resin molded product from returning into the other cavity by the locking portion that has returned to the original shape. The method according to claim 1, wherein The manufacturing method according to claim 1, wherein the locking portion has a dome shape. The part of the other cavity of the other side cavity is a protrusion protruding inward,
The manufacturing method according to claim 1, wherein the locking portion is formed of a portion adjacent to a recess formed by the protrusion. The pressed portion has a plurality of pressed elements,
The manufacturing method according to claim 1, wherein the ejector member has a plurality of ejector elements each having a tip shape corresponding to the shape of the corresponding pressed element. 7. The manufacturing method according to claim 1, wherein the resin molded product is a friction body of a thermochromic writing instrument. Cursive,
A tubular portion for accommodating the cursive body,
A resin friction body held in the tubular portion,
Equipped with
The cursive body includes at least a pen tip, an ink storage tube to which the pen tip is fixed, and a thermochromic ink filled in the ink storage tube,
A thermochromic writing instrument, wherein a dome-shaped raised portion is provided on a side surface of the friction body. Cursive,
A tubular portion for accommodating the cursive body,
A resin friction body held in the tubular portion,
Equipped with
The cursive body includes at least a pen tip, an ink storage tube to which the pen tip is fixed, and a thermochromic ink filled in the ink storage tube,
A groove extending in the axial direction is provided on the side surface of the friction body,
A thermochromic writing instrument, wherein at least one side of a cross section of the groove is inclined or curved.

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