JP2004249653A - Method for manufacturing resin molded article integrally bonded with piece of air permeable sheet and apparatus for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing capable of manufacturing a resin molded article with a stable quality even though thickness of a piece of an air permeable sheet is fluctuated, and an apparatus for manufacturing the same. <P>SOLUTION: In the first process S1, the piece 10 of the air permeable sheet is set on a placing face 8a of a receiving part 8. In the second process S2, at the same time when a core mold 1 and a cavity mold 2 are clamped, the piece 10 of the air permeable sheet is pinched by an annular projecting part 4b of a projecting part 4 and the placing face 8a of the receiving part 8, and is compressed in the thickness direction to form a compressed part 10c, and the projecting part 4 is retreated by a repulsion force of the piece 10 of the air permeable sheet against an energizing force of a compression coil spring 5. In the third process S3, a liquid resin is injected and filled in the cavity C. In the fourth process S4, the liquid resin is solidified or cured to integrally bond the piece 10 of the air permeable sheet on the resin molded article 21. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for manufacturing a resin molded product in which ventilation sheet pieces are integrally joined. INDUSTRIAL APPLICABILITY The production method and production apparatus of the present invention are suitable for use in the production of resin molded products such as case members and vent plugs in which air-permeable sheet pieces that pass air but do not pass water droplets or foreign matter are integrally joined.
[0002]
[Prior art]
BACKGROUND ART Conventionally, there has been known a method and an apparatus for manufacturing a resin molded product in which a ventilation sheet piece is integrally joined (Patent Document 1). This manufacturing method and manufacturing apparatus use the following injection mold.
[0003]
The injection mold has a first mold and a second mold that are openable and closable and have a cavity formed therein when closed, the cavity having a shape corresponding to the shape of the resin molded product. The first mold has a first mold body and a protrusion projecting from the first mold body into the cavity. The second mold has a second mold body that can be opened and closed with respect to the first mold body, and a receiving portion that can come into contact with the protrusion when the first mold body and the second mold body are closed. A portion of the ventilation sheet can be received between the projection and the receiving portion in the cavity. Further, when the first and second molds are closed, the ventilation sheet piece can be compressed in the thickness direction by sandwiching the ventilation sheet piece between the tip of the protruding portion and the receiving portion. Furthermore, the ventilation sheet piece can be exposed to the cavity on the outer peripheral side of the protrusion.
[0004]
In this manufacturing method, in the first step, when the first mold and the second mold are open, the ventilation sheet piece is set between the tip of the protruding portion in the cavity and the receiving portion. The ventilation sheet piece is usually a laminate in which a ventilation sheet main body and a reinforcing sheet are laminated. The ventilation sheet main body is made of polytetrafluoroethylene (PTFE), polypropylene (PP), or the like, in which an irregular number of fine ventilation holes of about 0.5 to 20 μm are formed, each of which has an irregular shape and faces in an irregular direction. . For this reason, this ventilation sheet main body has the property of allowing air to pass through but not allowing water droplets or foreign matter to pass through. The reinforcing sheet is a non-woven fabric made of a fiber such as polyester (PEs), and has a ventilation gap formed therein that is larger than the fine ventilation holes, is oriented in an irregular direction, and is formed in an irregular shape. For this reason, the reinforcing sheet has the property of allowing air to pass through. The ventilation sheet main body and the reinforcing sheet also have the property of being compressed in the thickness direction.
[0005]
Next, in this manufacturing method, in the second step, at the same time as closing the molds of the first mold and the second mold, the compressed sheet portion is compressed by sandwiching the breathable sheet piece in the thickness direction with the tip of the projecting portion and the receiving portion interposed therebetween. Form. Thereafter, in a third step, the molten liquid resin is injected and filled into the cavity to form a resin molded product having a ventilation hole at the protruding portion. The liquid resin is caused to flow into the fine ventilation holes in the remaining portion of the ventilation sheet piece while preventing the liquid resin from flowing between them. Then, the liquid resin is solidified or cured in the fine ventilation holes, and the ventilation sheet pieces are integrally joined to the resin molded product. The resin molded article thus obtained has a property that the ventilation sheet main body and the reinforcing sheet allow air to pass therethrough, and the ventilation sheet main body does not allow water droplets and foreign substances to pass therethrough. It is used for a vent plug attached to a through hole provided in a case such as this, preventing failure and malfunction of electronic components due to water droplets and foreign substances, and reducing internal pressure in a case member due to expansion of air due to heat generation of electronic components. By preventing the rise, the internal pressure in the case member is kept constant to the outside.
[0006]
According to this manufacturing method, the liquid resin is injected, the pressure at the time of filling causes the liquid resin to enter into the irregular vents of the gas permeable sheet piece in the irregular direction. The bonding strength between the resin molded product and the ventilation sheet piece is increased. Further, since the ventilation holes having the ventilation sheet pieces are formed at the same time as the molding of the resin molded article, the production efficiency is increased as compared with the case where the ventilation sheet pieces are attached with an adhesive after the molding of the resin molding article. Therefore, according to this manufacturing method, it is possible to efficiently manufacture a resin molded product having a larger bonding force with the ventilation sheet piece than bonding with an adhesive in a later step.
[0007]
[Patent Document 1]
JP-A-2002-347068
[Problems to be solved by the invention]
However, in the above-described conventional manufacturing method and manufacturing apparatus, the thickness of the air-permeable sheet is partially varied at the time of manufacturing, and the thickness of the air-permeable sheet is made by blanking the original into small pieces. In the case of a nominal thickness of 140 μm, when the thickness is 90 μm at the minimum portion and 180 μm at the maximum portion, the quality of the resin molded product may vary.
[0009]
That is, when a ventilation sheet piece thicker than a predetermined value is set in the cavity, the ventilation sheet piece may be excessively compressed by closing the mold before injecting the liquid resin. In this case, the ventilation sheet piece may be damaged, which may cause concerns about the waterproofness and durability of the resin molded product.
[0010]
Conversely, if a ventilation sheet piece thinner than a predetermined value is set in the cavity, the compression amount of the ventilation sheet piece is insufficient, and the injected liquid resin is placed between the ventilation sheet piece and the tip of the protrusion. There is a possibility that burrs may be generated on the surface of the ventilation sheet piece by flowing in, or the position of the ventilation sheet piece may be shifted due to the flow force of the injected resin.
[0011]
The present invention has been made in view of the above-mentioned conventional circumstances, and provides a manufacturing method and a manufacturing apparatus capable of manufacturing a resin molded product of stable quality regardless of a variation in thickness of a ventilation sheet piece. It is an issue to be solved.
[0012]
[Means for Solving the Problems]
The method for producing a resin molded product in which the breathable sheet pieces are integrally joined according to the present invention comprises a first mold and a second mold that can be opened and closed, and a shape corresponding to the shape of the resin molded product when both molds are closed. Wherein the first mold has a first mold body and a protruding portion projecting from the first mold body into the cavity, and the second mold has a second mold body. A receiving portion that can be opposed to and contact the protruding portion in the cavity when the first mold main body and the second mold main body are closed, and at least the protruding portion and the receiving portion Using an injection mold that is biased by biasing means having biasing force one of which is directed toward the cavity,
When both molds are open, in one of the tip of the protruding portion and the receiving portion in the cavity, an infinite number of irregularly shaped fine ventilation holes are formed in the inside, each of which has an irregular shape and faces in an irregular direction. A first step of setting a breathable sheet piece that is compressible in the thickness direction and that is larger than the outer shape of the protrusion;
Both molds are closed, and the center side portion is sandwiched between the tip of the protruding portion and the receiving portion and compressed in the thickness direction to form a compressed portion while leaving the outer portion of the ventilation sheet piece, A second step of retracting at least one of the protruding portion and the receiving portion against the urging force by a repulsive force of the ventilation sheet piece;
Injecting and filling a liquid resin into the cavity to form a resin molded product having a ventilation hole at the protruding portion, and between the tip of the protruding portion and the ventilation sheet piece at the compressed portion of the ventilation sheet piece. While preventing the liquid resin from flowing, the liquid resin flows into the fine ventilation holes in the remaining outside of the ventilation sheet piece, and the liquid resin flowing into the fine ventilation holes is solidified or cured. And a third step of integrally joining the ventilation sheet piece to the resin molded product.
[0013]
In the manufacturing method of the present invention, an injection mold in which at least one of the protruding portion and the receiving portion is provided so as to be able to move forward and backward is used. At least one of the protruding portion and the receiving portion is urged by urging means having an urging force directed toward the cavity. Then, in the first step, when the first mold and the second mold are open, a ventilation sheet piece similar to the conventional one is set between the tip of the protruding portion in the cavity and the receiving portion. Next, in the second step, at the same time as closing the molds of the first mold and the second mold, the compressed sheet portion is formed by sandwiching the ventilation sheet piece between the tip of the protruding portion and the receiving portion in the thickness direction. Thereafter, in a third step, a liquid resin is injected and filled into the cavity to form a resin molded product having an air hole in the protruding portion. While preventing the liquid resin from flowing in between, the liquid resin is caused to flow into the fine ventilation holes in the remaining of the ventilation sheet pieces, and the flowed liquid resin is solidified or hardened in the fine ventilation holes to form the ventilation sheet pieces. It is integrally joined to the product.
[0014]
In the above manufacturing method, in the second step, at least one of the protruding portion and the receiving portion is retracted against the urging force by the repulsive force of the ventilation sheet piece. For this reason, even if the thickness of the ventilation sheet piece varies from one ventilation sheet piece to another, the pressure applied to the compressed portion of the ventilation sheet piece becomes constant.
[0015]
That is, even when a ventilation sheet piece thicker than a predetermined value is set in the cavity, the ventilation sheet piece is not excessively compressed when the mold is closed before injection of the liquid resin. Therefore, the ventilation sheet piece is not damaged, and the waterproof performance and the like of the resin molded product are stabilized.
[0016]
Conversely, even when a ventilation sheet piece thinner than the predetermined value is set in the cavity, the compression force on the ventilation sheet piece does not become insufficient, and the ventilation sheet piece is securely held at the predetermined position and is sufficiently Is formed. Therefore, the liquid resin does not flow between the gas permeable sheet piece and the tip of the protruding portion to generate burrs on the gas permeable sheet piece, and the position of the gas permeable sheet piece does not shift during injection molding, so that a stable gas permeable performance is obtained. A resin molded product having the same can be obtained.
[0017]
Therefore, according to the manufacturing method of the present invention, a resin molded product of stable quality can be manufactured irrespective of variations in the thickness of the ventilation sheet pieces.
[0018]
In the manufacturing method according to the second aspect of the present invention, an annular projecting portion is formed at a portion of the tip of the projecting portion that comes into contact with the ventilation sheet piece, and the annular projecting portion and the receiving portion are formed in the second step. As a result, the ventilation sheet piece is compressed into an annular shape, and the ventilation sheet piece is maintained in a state in which the ventilation sheet piece is not compressed inside the annular protrusion of the ventilation sheet piece. As a result, only the portion of the ventilation sheet piece that contacts the annular projection is compressed, and the inside of the portion is not compressed, so that the ventilation performance of the ventilation sheet piece does not decrease.
[0019]
In the manufacturing method according to the third aspect of the present invention, the urging force is linearly changed in magnitude in proportion to the thickness of the ventilation sheet piece. Thus, in the second step, the gas-permeable sheet piece is compressed at a constant pressure by the annular protrusion and the receiving portion regardless of the thickness of the gas-permeable sheet piece.
[0020]
In the manufacturing method according to claim 4 of the present invention, when the ventilation sheet piece is a laminate, it is preferable to set the ventilation sheet piece in the first step with the reinforcing sheet side facing the cavity side. By setting the gas permeable sheet piece in this way, the liquid resin easily enters the remaining portion of the gas permeable sheet piece other than the compressed portion in the third step, whereby a stable bonding strength can be obtained.
[0021]
As the ventilation sheet pieces, a resin sheet body made of PTFE, PP, or the like, in which an infinite number of fine ventilation holes of about 0.5 to 20 μm having irregular shapes and facing each other are formed, may be employed. . The ventilation sheet main body having the fine ventilation holes allows air to pass therethrough, but prevents water droplets and foreign substances from passing therethrough. The ventilation sheet piece is a laminate of a ventilation sheet main body having a fine ventilation hole therein, and a reinforcing sheet having a ventilation gap formed in the irregular shape while being larger than the fine ventilation hole and facing each other in an irregular direction. It is preferable that The reinforcing sheet is a nonwoven fabric made of fibers such as PEs. It is also possible to adopt a laminate in which this reinforcing sheet is laminated in one or more layers on the resin sheet body. The laminate having the reinforcing sheet can be easily compressed in the thickness direction, and the strength of the ventilation sheet main body can be secured by the reinforcing sheet. Microtex (registered trademark) manufactured by Nitto Denko Corporation can be used as the resin sheet body and the laminate of the resin sheet body and the reinforcing sheet.
[0022]
In the manufacturing method according to claim 5 of the present invention, in the second step, the thickness of the ventilation sheet piece is 10 to 90% of the original thickness, preferably 30 to 70%, and most preferably 40 to 70%. Compress in the range. If the thickness of the compressed ventilation sheet is less than 10% of the original thickness, the ventilation sheet may be damaged when the mold is closed. If the thickness of the gas-permeable sheet piece exceeds 90% of the original thickness, the liquid resin may flow between the gas-permeable sheet piece and the tip of the projection when the liquid resin is injected. Therefore, by keeping the compressed thickness in the above range, resin leakage and unevenness of the ventilation sheet can be prevented, and a resin molded product of stable quality can be obtained.
[0023]
The manufacturing apparatus for a resin molded product according to claim 6 of the present invention, wherein the ventilation sheet pieces are integrally joined, the ventilation sheet having an infinite number of irregularly shaped fine ventilation holes formed therein, each having an irregular direction. A manufacturing apparatus for manufacturing a resin molded article in which pieces are integrally joined, the manufacturing apparatus comprising a first mold and a second mold that can be opened and closed, and when both molds are closed, the resin molded article is formed. A cavity having a shape corresponding to the shape is formed therein, the first mold has a first mold body, and a protrusion projecting into the cavity from the first mold body, and the second mold has An injection molding die having a second mold body, and a receiving portion that can face and contact the protruding portion in the cavity when the first mold body and the second mold body are closed;
At least one of the projecting portion and the receiving portion is provided so as to be able to move forward and backward in a state where the projecting portion and the receiving portion are biased by urging means having a biasing force directed toward the cavity. The gap between the ventilation sheet pieces is receivable when the molds of both types are closed and the ventilation sheet pieces are sandwiched between the tips of the protruding portions and the receiving portions and compressed in the thickness direction. At least one of the protruding portion and the receiving portion can be retracted by force, and the ventilation sheet piece can be exposed to the cavity on the outer peripheral side of the protruding portion.
[0024]
If the resin molded article is manufactured by the manufacturing apparatus of the present invention, as in the manufacturing method of the present invention, even if the thickness of the ventilation sheet piece varies from one ventilation sheet piece to another, the pressure applied to the ventilation sheet piece does not become excessive or insufficient. Thus, the compressed portion can be formed, and the ventilation sheet piece can be securely held at a predetermined position without being damaged.
[0025]
Therefore, even with the manufacturing apparatus of the present invention, a resin molded product of stable quality can be manufactured irrespective of variations in the thickness of the ventilation sheet pieces.
[0026]
In this manufacturing apparatus, the ventilation sheet piece can be exposed to the cavity on the outer peripheral side of the protruding portion when the first mold and the second mold are closed. For this reason, when the liquid resin is injected, the liquid resin enters the remaining portion of the ventilation sheet piece (the portion other than the compressed portion on the outer peripheral side of the protruding portion) and is solidified or hardened, so that stable bonding strength can be obtained.
[0027]
In the manufacturing apparatus according to claim 7 of the present invention, the protruding portion can move forward and backward. This is because the structure becomes simpler.
[0028]
In the manufacturing apparatus according to claim 8 of the present invention, the biasing means is a compression coil spring, and the compression coil spring is provided behind the projecting portion and / or the receiving portion that can move forward and backward. As the urging means, an air cylinder, a hydraulic cylinder, rubber, or the like can be adopted.However, if the urging force is applied by a compression coil spring, the structure of the manufacturing apparatus is simplified, and a reliable reciprocating operation is performed. Obtainable.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0030]
The manufacturing method of the embodiment is performed by the manufacturing apparatus shown in FIG. This manufacturing apparatus uses the following injection mold. The injection mold includes a core mold 1 as a first mold that can be opened and closed and a cavity mold 2 as a second mold. When both molds 1 and 2 are closed, a cavity having a shape corresponding to the shape of the resin molded product. C is formed inside.
[0031]
The core mold 1 has a core mold body 3 as a first mold body, a protrusion 4 projecting into the cavity C from the core mold body 3, and a rear end 4c of the protrusion 4 biasing the cavity C side. It comprises a compression coil spring 5 as a biasing means, and a plate 6 supporting the compression coil spring 5. An annular projection 4b having a recess 4d therein and projecting annularly is formed on the tip end surface 4a of the projection 4 on the cavity C side.
[0032]
The cavity mold 2 includes a cavity mold body 7 as a second mold body, and a receiving portion 8 that can abut on the protrusion 4. On the cavity C side of the receiving portion 8, a mounting surface 8a having a concave portion 8b at the center and capable of mounting the ventilation sheet piece 10 is formed. Further, a sprue 9 having an injection gate at the tip is provided between the core mold body 3 and the cavity mold body 7.
[0033]
Between the protruding portion 4 and the receiving portion 8 in the cavity C, the ventilation sheet piece 10 can be received. That is, the ventilation sheet piece 10 may be placed on the placement surface 8a as described above, or a recess 4d may be formed at the tip of the projection 4 and placed in the recess 4d. In addition, since the core mold 1 and the cavity mold 2 can be opened and closed, when the molds of the core mold 1 and the cavity mold 2 are closed, the ventilation sheet piece 10 is sandwiched between the tip of the protruding portion 4 and the receiving portion 8 in the thickness direction. Can be compressed. Further, on the outer peripheral side of the annular projection 4b, the ventilation sheet piece 10 can be exposed to the cavity C.
[0034]
As shown in FIG. 6, a method of manufacturing the plug-in type ventilation plug 20 which is a resin molded product in which the ventilation sheet pieces 10 are integrally joined will be described using the manufacturing apparatus having the above configuration.
[0035]
First, in the first step S1 shown in FIG. 1, as shown in FIG. 2, when the core mold 1 and the cavity mold 2 are open, the ventilation sheet piece 10 is placed on the mounting surface 8a of the receiving portion 8 of the cavity mold 2. Is set. The ventilation sheet piece 10 is a laminate in which a ventilation sheet main body 10a and a reinforcing sheet 10b are laminated, and is compressible in a thickness direction. The ventilation sheet main body 10a is made of PTFE (polytetrafluoroethylene resin) in which an infinite number of fine ventilation holes having sizes of about 0.5 to 20 μm are formed, each of which has an irregular shape and faces in an irregular direction. Further, the reinforcing sheet 10b is a non-woven fabric made of fibers such as PP (polypropylene resin) and PE (polyethylene resin), and has a size larger than the fine air holes inside, and is formed in an irregular direction and in an irregular shape. It has a ventilation gap. When setting the ventilation sheet piece 10 on the mounting surface 8a, the reinforcing sheet 10b side is set to the side in contact with the injected resin material, that is, the core sheet 1 in this embodiment.
[0036]
Next, in the second step S2 shown in FIG. 1, the molds (the core mold 1 and the cavity mold 2) are closed as shown in FIGS. The cavity C is formed by the part 4 and the ventilation sheet piece 10. At this time, the ventilation sheet piece 10 is sandwiched between the annular projection 4b of the projection 4 urged by the compression coil spring 5 and the mounting surface 8a of the receiving portion 8, and is compressed annularly in the thickness direction. However, the actual compressed thickness is a thickness corresponding to a position where the ventilation sheet piece 10 retreats the protrusion 4 somewhat against the urging force of the compression coil spring 5 due to its repulsive force. In this way, as shown in FIG. 5, an annular compressed portion 10 c is formed on the breathable sheet piece 10. The inner portion 10d of the ventilation sheet piece 10 radially inside the annular protrusion 4b is not compressed because the recess 4d of the protrusion 4 and the recess 8b of the receiving portion 8 are formed. Further, an outer portion 10e of the ventilation sheet piece 10 outside the annular protrusion 4b is exposed to the cavity C.
[0037]
In addition, the plurality of ventilation sheet pieces 10 have a thickness variation for each ventilation sheet piece 10 (in the case of a nominal thickness of 140 μm, a variation in the range of 90 μm to 180 μm). The urging force linearly changes in proportion to the thickness of the sheet piece 10. The compression coil spring 5 is adjusted so that the thickness of the compression portion 10c is approximately 50% of the original thickness of the breathable sheet piece 10 having the nominal thickness. As shown in FIGS. 3 and 4, the distance d1 or d2 between the rear end 4c of the protruding portion 4 and the core mold body 3 absorbs variations in the thickness of the ventilation sheet piece 10 due to the mold structure. Indicates a state in which 3 shows a case where the ventilation sheet piece 10 is thinner than a predetermined value, and FIG. 4 shows a case where the ventilation sheet piece 10 is thicker than a predetermined value.
[0038]
Next, in a third step S3 shown in FIG. 1, a liquid resin is injected into the cavity C from the injection gate of the sprue 9 and filled therein, as shown in FIGS. At this time, as shown in FIG. 5, since the ventilation sheet piece 10 is compressed in an annular shape to form a compression portion 10 c which is in close contact with the tip of the annular protrusion 4 b, the liquid flows into the inside 10 d of the ventilation sheet piece 10. Inflow of resin is prevented. Also, due to the pressure of the liquid resin, the liquid resin flows into the ventilation gap on the outside 10e of the ventilation sheet piece 10. When the plug-in type vent plug 20 is molded according to the present embodiment, as a material of the liquid resin, TPE (thermoplastic elastomer), TPO (olefin-based thermoplastic elastomer), EPDM (ethylene-propylene-diene copolymer) And those having rubber-like elasticity such as PVC (polyvinyl chloride) can be used, and TPO is particularly preferable from an environmental point of view.
[0039]
Then, the liquid resin is solidified or cured in the ventilation gap, and the ventilation sheet piece 10 is integrally joined to the plug-in ventilation plug 20 by an anchoring action.
[0040]
Finally, in a fourth step S4 shown in FIG. 1, the mold is opened to obtain the plug-in type vent plug 20 shown in FIG. In this plug-in type ventilation plug 20, the ventilation sheet piece 10 is integrally joined to the resin molded product 21, the ventilation sheet body 10a and the reinforcing sheet 10b of the ventilation sheet piece 10 allow air to pass, and the ventilation sheet body 10a Since it has the property of not allowing liquids such as water droplets and foreign substances exceeding the size of fine ventilation holes to pass through, it is used, for example, as a vent plug for a case that contains electronic components, and malfunctions of electronic components due to adhesion of water etc. In addition, the internal pressure in the case member is prevented from rising due to the expansion of air accompanying the heat generated by the electronic components, and the internal pressure in the case member is kept constant to the outside.
[0041]
In this manufacturing method, in the second step S2, the projecting portion 4 is retracted against the urging force of the compression coil spring 5 by the repulsive force of the ventilation sheet piece 10. For this reason, even if the thickness of the ventilation sheet piece 10 varies from one ventilation sheet piece 10 to the next, the pressure applied to the ventilation sheet piece 10 is not excessive or insufficient, and the compressed portion 10c can be formed.
[0042]
That is, even when the ventilation sheet piece 10 thicker than the predetermined value is set in the cavity C, the ventilation sheet piece 10 is not excessively compressed when the mold is closed before the injection of the liquid resin. Therefore, the ventilation sheet piece 10 is not damaged, and the waterproof performance and the like of the resin molded product 21 are stabilized.
[0043]
Further, even when the ventilation sheet piece 10 thinner than the predetermined value is set in the cavity C, the compressive force on the ventilation sheet piece 10 does not become insufficient, and the ventilation sheet piece 10 is securely held at the predetermined position. Then, a sufficiently compressed compression section 10c is formed. Therefore, the liquid resin does not flow between the gas permeable sheet piece 10 and the tip of the protruding portion 4 to generate burrs on the gas permeable sheet piece 10 and the position of the gas permeable sheet piece 10 does not shift during injection molding, and is stable. A resin molded product having improved ventilation performance can be obtained.
[0044]
Further, in the first step S1, the ventilation sheet piece 10 is set with the reinforcing sheet 10b having a ventilation interval larger than the fine ventilation hole facing the core mold 1 (the side filled with the liquid resin). Since the outer side 10e of the ventilation sheet piece 10 outside the annular projection 4b is exposed to the cavity C in the second step S2, the liquid resin easily enters the inside of the outer side 10e in the third step S3. In addition, the inside 10d of the ventilation sheet piece 10 inside the annular protrusion 4b is not compressed by the formation of the concave portions 4d and 8b, so that the ventilation performance of the ventilation sheet piece 10 does not decrease. .
[0045]
Therefore, according to the manufacturing method of the present invention, it is possible to manufacture the resin molded product 21 of stable quality regardless of the variation in the thickness of each breathable sheet piece 10.
[0046]
Further, according to this manufacturing method, the liquid resin is solidified or hardened in a state in which the liquid resin enters into the fine ventilation holes and the ventilation gaps of the ventilation sheet piece 10 in the irregular direction by the injection and filling pressure of the liquid resin, so that the anchoring action is obtained. Thereby, the joining force between the resin molded article 21 and the ventilation sheet piece 10 can be obtained without an additional step. Further, since the ventilation holes having the ventilation sheet pieces 10 are formed at the same time as the molding of the resin molded article 21, the number of steps is smaller than in the case where the ventilation sheet pieces 10 are pasted with an adhesive after the molding of the resin molded article 21. The production efficiency can be improved. Therefore, according to this manufacturing method, it is possible to efficiently manufacture the plug-in type ventilation plug 20 having a larger bonding force with the ventilation sheet piece 10 than the bonding with the adhesive in a later step.
[0047]
In the above embodiment, as an example of a resin molded product, a method of manufacturing a vent plug for closing a ventilation hole of a case and a manufacturing apparatus thereof have been described. The ventilation sheet pieces may be integrally joined so as to close the formed ventilation holes. If the overall shape of the resin molded product is small, a plurality of resin molded products may be formed simultaneously in one core mold 1 and cavity mold 2.
[0048]
Further, in the above embodiment, the compression coil spring 5 as the urging means is provided on the protruding portion 4 (the core mold 1 side), but may be provided on the receiving portion 8 (the cavity mold 2 side). Further, it may be provided on both the protruding portion 4 and the receiving portion 8.
[Brief description of the drawings]
FIG. 1 is a process diagram of a method for manufacturing a resin molded product in which air-permeable sheet pieces are integrally joined according to an embodiment.
FIG. 2 is a cross-sectional view illustrating a state where a mold is opened according to the embodiment.
FIG. 3 is a cross-sectional view of a state in which a mold is closed when a ventilation sheet piece is thin according to the embodiment.
FIG. 4 is a cross-sectional view showing a state in which a mold is closed when a ventilation sheet piece is thick according to the embodiment.
FIG. 5 is a partially enlarged cross-sectional view of a state where a mold is closed according to the embodiment.
FIG. 6 is a perspective view of a product according to the embodiment.
[Explanation of symbols]
1: First type (core type)
2nd mold (cavity mold)
3. First-type main body (core-type main body)
7 2nd mold body (cavity mold body)
4 Projecting portion 4b Annular projecting portion 8 Receiving portion 5 Urging means (compression coil spring)
C: cavity 10: ventilation sheet piece 10a: ventilation sheet body 10b: reinforcing sheet 10c: compression section

Claims (8)

The first mold includes a first mold and a second mold that can be opened and closed, and when both molds are closed, a cavity having a shape corresponding to the shape of the resin molded product is formed therein. The first mold includes a first mold body, A projecting portion projecting from the first mold body into the cavity, wherein the second mold has a second mold body, and the first mold body and the second mold body are closed when the first mold body and the second mold body are closed. A receiving portion that can be opposed to and contact the protruding portion in the cavity, and at least one of the protruding portion and the receiving portion is urged by urging means having an urging force directed to the cavity side; Using an injection mold,
When both molds are open, in one of the tip of the protruding portion and the receiving portion in the cavity, an infinite number of irregularly shaped fine ventilation holes are formed in the inside, each of which has an irregular shape and faces in an irregular direction. A first step of setting a breathable sheet piece that is compressible in the thickness direction and that is larger than the outer shape of the protrusion;
Both molds are closed, and the center side portion is sandwiched between the tip of the protruding portion and the receiving portion and compressed in the thickness direction to form a compressed portion while leaving the outer portion of the ventilation sheet piece, A second step of retracting at least one of the protruding portion and the receiving portion against the urging force by a repulsive force of the ventilation sheet piece;
Injecting and filling a liquid resin into the cavity to form a resin molded product having a ventilation hole at the protruding portion, and between the tip of the protruding portion and the ventilation sheet piece at the compressed portion of the ventilation sheet piece. While preventing the liquid resin from flowing, the liquid resin flows into the fine ventilation holes in the remaining outside of the ventilation sheet piece, and the liquid resin flowing into the fine ventilation holes is solidified or cured. And a third step of integrally joining the gas permeable sheet piece to the resin molded article. At a portion of the tip of the protruding portion that contacts the ventilation sheet piece, an annular protruding portion that protrudes in an annular shape is formed,
In the second step, the ventilation sheet piece is compressed into an annular shape by the annular projection and the receiving portion, and the ventilation sheet piece is not compressed inside the ventilation sheet piece inside the annular projection. A method for producing a resin molded product, wherein the breathable sheet pieces according to claim 1 are integrally joined. 3. The method according to claim 1, wherein said urging force is linearly changed in magnitude in proportion to the thickness of said ventilation sheet piece. . The ventilation sheet piece has a ventilation sheet main body having the fine ventilation holes therein, and a reinforcing sheet having a ventilation gap formed therein which is larger than the fine ventilation holes and is oriented in an irregular direction with respect to each other. A laminate of
The ventilation sheet piece according to any one of claims 1 to 3, wherein, in the first step, the ventilation sheet piece is set with the reinforcing sheet side facing the cavity side. Manufacturing method of joined resin molded products. The said 2nd process WHEREIN: The thickness of the said ventilation sheet piece is compressed in the range which becomes 10-90% of the original thickness, The ventilation sheet piece of any one of Claims 1 thru | or 4 characterized by the above-mentioned. A method of manufacturing integrally molded resin products. A manufacturing apparatus for manufacturing a resin molded product in which an infinite number of fine ventilation holes each having an irregular shape and facing each other in an irregular shape are integrally joined, and a resin molded product is integrally joined. The first mold includes a first mold and a second mold that can be opened and closed, and when both molds are closed, a cavity having a shape corresponding to the shape of the resin molded product is formed therein. The first mold includes a first mold body, A projecting portion projecting from the first mold body into the cavity, wherein the second mold has a second mold body, and the first mold body and the second mold body are closed when the first mold body and the second mold body are closed. An injection mold having a receiving portion that can be abutted against the protruding portion in the cavity,
At least one of the projecting portion and the receiving portion is provided so as to be able to move forward and backward in a state where the projecting portion and the receiving portion are biased by urging means having a biasing force directed toward the cavity. The gap between the ventilation sheet pieces is receivable when the molds of both types are closed and the ventilation sheet pieces are sandwiched between the tips of the protruding portions and the receiving portions and compressed in the thickness direction. At least one of the protruding portion and the receiving portion can be retracted by force, and the vent sheet piece can be exposed to the cavity on the outer peripheral side of the protruding portion. Manufacturing equipment for molded resin products. 7. The apparatus for manufacturing a resin molded product according to claim 6, wherein the protruding portion is movable forward and backward. The ventilation according to claim 6 or 7, wherein the urging means is a compression coil spring, and the compression coil spring is provided behind the projecting portion and / or the receiving portion that can move forward and backward. An apparatus for manufacturing resin molded products in which sheet pieces are integrally joined.

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