JP2009220406A - Method and apparatus for molding resin molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the size of the opening part and a notch part of a resin molding from becoming larger than a desired size, in a method and an apparatus for molding the resin molding. <P>SOLUTION: By supplying a molten expandable resin 70 into the first and second cavity parts 27a and 27b of the cavity 27 of a mold 4, a bottom wall part 50b which is made of the molten expandable resin 70a supplied into the first cavity part 27a and thinner than the main part 50a of the resin molding 50 is formed to be continuous with the molten expandable resin 70b supplied into the second cavity part 27b. By executing a core-backing operation only for a part corresponding to the second cavity part 27b in the mold 4 and expanding all the molten expandable resin 70b supplied into the second cavity part 27b, the main part 50a having an opening part 51 in which the bottom wall part 50b is formed at the end on the fixed mold 21 side is formed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a molding method and a molding apparatus for a resin molded product.

Conventionally, a resin molded product molded by injection molding or the like using a resin made of polypropylene or the like has been used for automobiles or the like. Here, from the viewpoints of strength, heat insulation, sound insulation, vibration proofing, shock absorption, etc., the resin contains a physical foaming agent such as nitrogen or carbon dioxide, or a chemical foaming agent such as sodium hydrogen carbonate. In some cases, a resin molded product is molded by vaporizing the foaming agent during molding. For example, as shown in Patent Document 1, such a resin molded product is supplied with a melt-foamable resin (melted by mixing a foaming agent in a melted resin obtained by melting a resin) in a cavity of a mold. After that, the molding die is core-backed to mold the melt-foamable resin. The resin molded product molded in this way has a shape that is several times larger than before the core back due to foaming of the melt-foamable resin while maintaining the shape of the cavity as viewed from the core back direction. ing.
Japanese Patent Laid-Open No. 11-156881

  By the way, when the present inventors have studied and studied in detail about the molding of a resin molded product using a core back, when molding a resin molded product in which an opening or a notch is formed, these opening and We encountered the problem that the notch spreads outward and its size is larger than desired. For this reason, for example, even if a member is fitted to the opening of the resin molded product, the member is detached from the opening, or the member is fitted or positioned using a notch, There is a risk of rattling.

  Such a phenomenon is considered to occur for the following reasons. Hereinafter, this cause will be described with reference to FIGS.

  As shown in FIG. 18A, a concave portion 121a is formed on the surface of the fixed die 121 of the molding die on the movable die 122 side, and the movable die 122 is formed on the surface of the fixed die 121 side. And has a convex portion 122a for forming the opening 151. The convex portion 122a is slidably fitted into the concave portion 121a. Then, after the melt-foamable resin 170 is supplied into the cavity 127 of the mold, as shown in FIG. 18B, the mold is core-backed and the melt-foamable resin 170 is foamed while increasing the cavity 127. Thus, the resin molded product 150 in which the opening 151 is formed is molded. The resin molded product 150 is formed by covering an inner portion 150b with a surface layer portion 150a in contact with a forming surface (inner surface) of a cavity 127 of a mold.

  Here, the opening 151 is ideally in contact with the side surface (vertical surface) of the convex portion 122a of the movable mold 122 (see FIG. 18B). That is, if the surface layer portion 170a of the melt-foamable resin 170 in the cavity 127 has sufficient extensibility at the time of core back, the surface layer portion 170a becomes the inner portion 170b of the melt-foamable resin 170 in the cavity 127. It is pressed against the mold by receiving the foaming pressure from and follows the increasing cavity 127.

  However, in reality, the surface layer portion 170a is cooled at the start of the core back or during the core back, and its extensibility is lowered. Therefore, the surface layer portion 170a receives a foaming pressure from the inner portion 170b of the melt foamable resin 170 in the cavity 127. However, it becomes difficult to expand. For this reason, as shown in FIG. 18C, the surface layer portion 170 a cannot sufficiently follow the increasing cavity 127, and the inner surface 170 b of the melt-foamable resin 170 in the cavity 127 is not able to follow. The portion receiving the foaming pressure is relatively small, that is, the opening 151 is retracted and retracted to the opposite side of the convex portion 122a of the movable mold 122 at the time of core back, and the opening 151 and the convex portion 122a A gap s is formed between them. As a result, as shown in FIG. 19, the size of the opening 151 is larger than the desired size (see the two-dot chain line in FIG. 19), and the claw of the mating member is fitted into this opening 151. In addition, there is a possibility that the nail part may come off from the opening 151.

  The same can be said for molding a resin molded product having a notch. That is, a gap is formed between the notch portion and the convex portion 122a of the movable mold 122, and as shown in FIG. 20, the notch portion 152 has a desired size (see the two-dot chain line in FIG. 20). Even if the notched portion 152 is used to fit or position the protruding portion of the mating member, the protruding portion may come off from the notched portion 152 or be rattled.

  This invention is made | formed in view of this point, The place made into the objective is to suppress that the opening part and notch part of a resin molded product become larger than desired magnitude | size.

  According to a first aspect of the present invention, a melt-foamable resin is supplied into a cavity of a molding die composed of a fixed mold and a movable mold, and the melt-foamable resin supplied into the cavity is core-backed to the mold. A method for molding a resin molded product, which is formed by foaming to form a resin molded product having a main body having an opening or a notch, wherein the cavity corresponds to the opening or the notch. And a first cavity portion formed at a position corresponding to a portion of the main body portion other than the opening portion or the notch portion, and the first and second cavities. By supplying the melt-foamable resin into the part, a bottom wall part made of the melt-foamable resin supplied into the first cavity part and thinner than the thickness of the main body part is placed in the second cavity part. All the melt-foamable resin supplied into the second cavity portion is formed by core-backing only the portion corresponding to the second cavity portion of the molding die. By foaming, a body part having an opening or a notch part in which the bottom wall part is formed at an end part on the fixed mold side is formed.

  Accordingly, by supplying the melt-foamable resin into the first and second cavity portions, the bottom wall portion made of the melt-foamable resin supplied into the first cavity portion and thinner than the thickness of the main body portion is formed in the second cavity. Since it forms so that the molten foamable resin supplied in the part may follow, it can suppress that an opening part and a notch part spread outward by this bottom wall part. Therefore, it can suppress that the magnitude | size of the opening part of a resin molded product or a notch becomes larger than desired magnitude | size.

  A second invention is characterized in that, in the first invention, the melt-foamable resin is simultaneously supplied into the first and second cavities.

  Accordingly, since the melt-foamable resin is simultaneously supplied into the first and second cavities, the bottom wall can be formed at an appropriate timing.

  According to a third invention, in the first or second invention, the bottom wall portion is a portion of the peripheral portion of the first cavity portion of the melt-foamable resin supplied into the second cavity portion that faces each other. Is formed so as to be connected.

  As a result, the bottom wall portion is formed so as to connect the opposing portions of the peripheral edge portion of the first cavity portion in the melt-foamable resin supplied into the second cavity portion. It can suppress more reliably that a part and a notch part spread outward.

  According to a fourth invention, in any one of the first to third inventions, the melt-foamable resin contains a physical foaming agent.

  As a result, since the melt-foamable resin contains a physical foaming agent, the expansion ratio of the melt-foamable resin is increased. Therefore, if no measures are taken, the size of the opening or notch of the resin molded product is small. Although it is a situation that tends to be larger than a desired size, according to the present invention, it can be suppressed.

  Moreover, the average foamed cell diameter of the resin molded product can be made relatively small, and the strength of the resin molded product can be reliably improved.

  According to a fifth invention, in the fourth invention, the physical foaming agent comprises a supercritical fluid.

  As a result, since the physical foaming agent is made of a supercritical fluid, the foaming ratio is further increased. Therefore, if no measures are taken, the size of the opening or notch of the resin molded product is further increased. Although it is a situation that tends to be larger than a desired size, according to the present invention, it can be suppressed.

  In addition, by utilizing the fact that supercritical fluid has both viscosity and dissolving power as a liquid and intense molecular motion as a gas, the foam cell of the resin molded product can be made ultrafine, and the resin molded product The strength can be improved even more reliably.

  6th invention is equipped with the shaping | molding die comprised by the fixed mold | type and the movable mold | type, and the supply means which supplies molten foamable resin in the cavity of this shaping | molding mold, The said fusion | melting is carried out in the said cavity by this supply means A resin molded product having a main body portion having an opening or a notch is supplied by supplying a foamable resin, foaming the melt-foamable resin supplied into the cavity by core-backing the mold. An apparatus for molding a resin molded product to be molded, wherein the cavity includes a first cavity portion formed at a position corresponding to the opening or the notch, and a portion other than the opening or the notch in the main body. A second cavity portion formed at a position corresponding to the portion, and by supplying the molten foamable resin into the first and second cavity portions by the supply means, A bottom wall portion made of a melt-foamable resin supplied into one cavity portion and thinner than the thickness of the main body portion is formed so as to be continuous with the melt-foamable resin fed into the second cavity portion, and the mold The core portion of only the portion corresponding to the second cavity portion is core-backed to foam all the melt-foamable resin supplied into the second cavity portion, whereby the bottom wall portion is formed at the end on the fixed mold side. A main body having a formed opening or notch is formed.

  Thus, by supplying the melt foamable resin into the first and second cavities by the supply means, the bottom wall portion made of the melt foamable resin supplied into the first cavity portion and thinner than the thickness of the main body portion is formed. Since it forms so that the molten foamable resin supplied in the 2nd cavity part may be followed, it can suppress that an opening part and a notch part spread outward by this bottom wall part. Therefore, it can suppress that the magnitude | size of the opening part of a resin molded product or a notch becomes larger than desired magnitude | size.

  The seventh invention is characterized in that, in the sixth invention, the supply means is configured to supply the melt-foamable resin into the first and second cavities at the same time. .

  Thereby, since a supply means supplies molten foamable resin simultaneously in the 1st and 2nd cavity part, a bottom wall part can be formed at a suitable timing.

  According to an eighth aspect of the present invention, in the sixth or seventh aspect of the invention, in the molding die, the bottom wall portion of the peripheral portion of the first cavity portion in the melt-foamable resin supplied into the second cavity portion, It is configured to be formed so as to connect portions facing each other.

  Thus, the mold is configured such that the bottom wall portion is formed so as to connect the opposing portions of the peripheral edge portion of the first cavity portion in the melt-foamable resin supplied into the second cavity portion. Therefore, the bottom wall portion can more reliably suppress the opening and the notch from spreading outward.

  According to a ninth invention, in any one of the sixth to eighth inventions, the movable mold is disposed at a position corresponding to the first cavity portion and has a side surface extending substantially in the core back direction. Part and a movable part arranged at a position corresponding to the second cavity part, and by moving only the movable part of the movable mold to the side opposite to the fixed mold, the molding is performed. Only a portion of the mold corresponding to the second cavity portion is core-backed.

  As a result, by moving only the movable part of the movable mold to the side opposite to the fixed mold, only the part corresponding to the second cavity part of the molding mold is cored back. It is possible to form a main body having an opening or a notch in which a bottom wall is formed at the end.

  In a tenth aspect of the invention according to any one of the sixth to ninth aspects, the melt-foamable resin contains a physical foaming agent.

  Thereby, the same effect as that of the fourth invention can be obtained.

  In an eleventh aspect based on the tenth aspect, the physical foaming agent comprises a supercritical fluid.

  Thereby, the same effect as that of the fifth aspect can be obtained.

  According to the present invention, by supplying the melt-foamable resin into the first and second cavity portions, the bottom wall portion made of the melt-foamable resin fed into the first cavity portion and thinner than the thickness of the main body portion is formed. Since it is formed so as to be continuous with the melt-foamable resin supplied into the second cavity portion, the bottom wall portion can prevent the opening portion and the notch portion from spreading outward, and the resin molded product It can suppress that the magnitude | size of an opening part and a notch part becomes larger than desired magnitude | size.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

-Configuration of molding equipment for resin molded products-
FIG. 1 shows a molding apparatus 1 according to Embodiment 1 of the present invention, which molds a resin molded product 50 using a melt-foamable resin 70. The resin molded product 50 can be used for a wide range of applications such as for automobiles, building materials, household appliances, and household goods. In each application, the resin molded product 50 is composed of a reinforcing material, a heat insulating material, and a sound insulation. It can be used as a material, a vibration isolating material, a shock absorbing material, or the like. In the present embodiment, the resin molded product 50 is a ventilation duct that is assembled to the back surface of the instrument panel 60 of the automobile, as shown in FIG. An opening 51 having a rectangular shape is formed in the main body 50a of the resin molded product 50 when viewed from directly above. The opening 51 is fitted with a clip claw 61 on the back surface of the instrument panel 60.

  As shown in FIG. 1, the molding apparatus 1 includes a molding die 4 and a resin supply device 7 (supplying unit) that supplies a melt-foamable resin 70 into the cavity 27 of the molding die 4.

  The molding die 4 includes a fixed die 21 and a movable die 22 that slides in the horizontal direction (left-right direction in FIG. 1) with respect to the fixed die 21 to perform mold closing and mold opening. The movable mold 22 includes a fixed portion 22a for forming the opening 51 and a movable portion 22b. The fixed portion 22a is configured to approach and separate from the fixed mold 21 by a drive mechanism (not shown). The fixed portion 22a has a quadrangular shape when viewed from the fixed mold 21 side, and the side surface (vertical surface) of the fixed portion 22a extends in the horizontal direction (core back direction). The movable portion 22b is disposed around the fixed portion 22a and is moved toward and away from the fixed mold 21 by a drive mechanism (not shown) different from the drive mechanism that drives the fixed portion 22a. It is configured as follows. In the basic state of the movable portion 22b, the surface of the movable portion 22b on the fixed mold 21 side is flush with the tip surface of the fixed portion 22a.

  When the mold is closed, the fixed part 22a and the movable part 22b in the basic state are both moved to the fixed mold 21 side, and the fixed part 22a and the movable part 22b are both a predetermined distance from the fixed mold 21. The mold closing is completed by separating only by. Further, when the molding die 4 is core-backed as described later, only the movable portion 22b is opposite to the stationary die 21 while the stationary portion 22a is kept away from the stationary die 21 by the predetermined distance. To move to. Further, when the mold is opened after the molding is completed, both the fixed portion 22a and the movable portion 22b move to the opposite side of the fixed die 21, and the movable portion 22b moves relative to the fixed portion 22a to move the basic portion. Return to state.

  The resin supply device 7 guides the injection-molding machine 5 for injecting the melt-foamable resin 70 and the melt-foamable resin 70 provided in the fixed mold 21 and injected from the injection molding machine 5 into the cavity 27. And a resin introducing portion 6 for the purpose.

  The resin introduction portion 6 is provided with a hot runner 32 (resin introduction passage. The details of the hot runner 32 are not shown for easy understanding). The hot runner 32 is kept higher than the solidification temperature of the melt-foamable resin 70. Have. The hot runner 32 penetrates the fixed mold 21 in the thickness direction of the fixed mold 21 (the left-right direction in FIG. 1).

  The injection molding machine 5 has a cylindrical injection cylinder 41. A nozzle 41 a is provided at the front end of the injection cylinder 41, and the nozzle 41 a is connected to an opening on the opposite side of the hot runner 32 from the movable die 22. In addition, a screw 42 is provided inside the injection cylinder 41 so as to be rotatable and movable back and forth. A drive mechanism (not shown) for driving the screw 42 is provided on the rear end side of the screw 42.

  A hopper 43 for charging resin pellets 71 is connected to the upper portion of the rear end portion of the injection cylinder 41, and the resin pellets 71 loaded into the hopper 43 are supplied into the injection cylinder 41. It has become. In addition, a plurality of heaters (not shown) are installed on the peripheral wall portion of the injection cylinder 41 so as to be arranged in the front-rear direction of the injection cylinder 41. The resin pellet 71 supplied from the hopper 43 into the injection cylinder 41 is melted by the heater while moving to the front side of the injection cylinder 41 by the rotation of the screw 42 by the drive mechanism. Yes.

  An injection nozzle 45 for injecting a supercritical fluid into the injection cylinder 41 is connected to an intermediate portion in the front-rear direction of the injection cylinder 41. The injection nozzle 45 is connected to a supercritical fluid supply device 46 that supplies a gas such as nitrogen or carbon dioxide as a supercritical fluid (a state exceeding the critical pressure and critical temperature). The supercritical fluid is injected into the injection cylinder 41 from the injection nozzle 45 by the device 46. As a result, the supercritical fluid is mixed and dissolved in the molten resin obtained by melting the resin pellets 71 to form the molten foamable resin 70, and the supercritical fluid is vaporized at the time of molding. Will foam. That is, in the present embodiment, the supercritical fluid is used as a foaming agent in order to perform ultrafine foam molding using the properties of the supercritical fluid, that is, the properties having both the viscosity and dissolving power as a liquid and intense molecular motion as a gas. A physical foaming agent consisting of The resin pellet 71 is made of, for example, polypropylene, polyethylene, polystyrene, or the like.

  The melt-foamable resin 70 is pushed out to the front portion of the screw 42 in the injection cylinder 41 by the rotation of the screw 42. At this time, the screw 42 is retracted by the pressure, and only a predetermined distance (a distance such that the amount of the melt-foamable resin 70 necessary for one injection is accommodated in the front portion of the screw 42 in the injection cylinder 41). When retreating, the screw 42 stops rotating. Thus, the melt-foamable resin 70 supplied into the cavity 27 of the mold 4 is accommodated in the front portion of the screw 42 in the injection cylinder 41. When the molten foamable resin 70 is injected, the screw 3 is advanced at a high speed by the drive mechanism. As a result, the melt-foamable resin 70 is supplied from the nozzle 41 a through the hot runner 32 into the cavity 27 of the mold 4.

  Below, the characteristic part of this invention is demonstrated in detail.

  The cavity 27 is formed at a position corresponding to the opening 51 of the main body 50a of the resin molded product 50, and has a first cavity 27a that is rectangular when viewed from the horizontal direction, and an opening in the main body 50a. The second cavity portion 27b is formed at a position corresponding to a portion other than the portion 51. The movable mold 22 has a fixed portion 22a disposed at a position corresponding to the first cavity portion 27a (a position corresponding to the opening portion 51) and a position corresponding to the second cavity portion 27b (an opening portion in the main body portion 50a). And the movable portion 22b disposed at a position corresponding to a portion other than 51). Then, as shown in FIG. 3, by simultaneously supplying the melt-foamable resin 70 into the first and second cavities 27a and 27b by the injection molding machine 5 and the resin introduction part 6, the inside of the first cavity part 27a. The bottom wall portion 50b, which is made of the melt-foamable resin 70a supplied to the substrate and thinner than the thickness of the main body portion 50a as viewed in the horizontal direction, has a rectangular shape when viewed from the horizontal direction. It is formed so as to be continuous with the supplied melt-foamable resin 70b. That is, the bottom wall portion 50b is formed so as to connect (connect) mutually opposing portions of the peripheral edge portion of the first cavity portion 27a in the melt foamable resin 70b supplied into the second cavity portion 27b. In other words, in the molding die 4, the bottom wall portion 50b is formed so as to connect mutually opposing portions of the peripheral edge portion of the first cavity portion 27a in the melt-foamable resin 70b supplied into the second cavity portion 27b. It is configured to be. Thereafter, as shown in FIG. 4, only the movable portion 22 b of the movable mold 22 is moved to the opposite side to the fixed mold 21, so that only the portion corresponding to the second cavity portion 27 b of the mold 4 is core-backed. Then, all the melt-foamable resin 70b supplied into the second cavity portion 27b is foamed, so that it is formed at a position corresponding to the fixed portion 22a and at the end on the fixed mold 21 side (core back direction start end side). A main body 50a having an opening 51 in which the bottom wall 50b is formed is formed. The bottom wall portion 50b closes all ends of the opening 51 on the fixed mold 21 side. That is, the main body 50a has a recess. In FIG. 4, illustration of the surface layer portion and the inner portion of the melt-foamable resin 70 is omitted for easy understanding of the drawing (the same applies to FIGS. 6 to 8 below).

-Molding method of resin molded products-
Next, a method for molding the resin molded product 50 using the molding apparatus 1 will be described.

  First, as shown in FIG. 1, the mold 4 is closed, and the screw 42 of the injection molding machine 5 is advanced at a high speed as shown in FIGS. The molten foamable resin 70 accommodated in the front portion 42 is injected. That is, the high-pressure melt-foamable resin 70 is simultaneously supplied from the opening on the movable mold 22 side in the hot runner 32 into the first and second cavity portions 27 a and 27 b of the cavity 27 of the mold 4. In addition, before injecting the melt-foamable resin 70 by the injection molding machine 5 as described above, the melt-foamable resin 70 supplied into the cavity 27 is accommodated in the front portion of the screw 42 in the injection cylinder 41 in advance. Keep it like that.

  When the supply of the melt-foamable resin 70 into the cavity 27 is completed, the cavity 27 is filled with the melt-foamable resin 70.

  The melt-foamable resin 70a supplied into the first cavity portion 27a has its resin temperature lowered by natural cooling from the start of supply into the first cavity portion 27a, and the resin temperature reaches the solidification temperature and reaches a predetermined value. As time elapses, it completely solidifies (hardens). When the melt-foamable resin 70 is solidified in this way, foaming stops and the foamed cell diameter does not increase any further. The melt-foamable resin 70a supplied into the first cavity portion 27a is completely solidified to form a rectangular bottom wall portion 50b when viewed from the horizontal direction. Around the entire circumference of the bottom wall portion 50b, the melt-foamable resin 70b supplied into the second cavity portion 27b is continuously arranged.

  After completion of the supply of the melt-foamable resin 70 into the cavity 27 (after completion of filling) and completion of solidification of the bottom wall portion 50b, only the movable portion 22b of the movable mold 22 is shown in FIGS. Is moved to the opposite side of the fixed mold 21 by a predetermined amount (predetermined depending on how much the foam cell diameter is to be set), so that only the portion of the mold 4 corresponding to the second cavity portion 27b is moved. All the melt-foamable resin 70b supplied into the second cavity part 27b is foamed while being opened in the mold opening direction (core back) to increase the second cavity part 27b. That is, the adjacent portion (opposed portion) of the side surface of the fixed portion 22a of the movable mold 22 in the melt-foamable resin 70 supplied into the second cavity portion 27 is also foamed. Thus, the mold 4 causes the molten foamable resin 70b supplied into the second cavity part 27b to foam while increasing the volume of the second cavity part 27b by core back. Thus, since the volume of the 2nd cavity part 27b increases, foaming of the melt foamable resin 70b supplied in the 2nd cavity part 27b is accelerated | stimulated. Further, as described above, since the bottom wall portion 50b is formed so as to be continuous with the melt-foamable resin 70b supplied into the second cavity portion 27b, the opening portion 51 is formed outward by the bottom wall portion 50b. Therefore, it is possible to prevent a gap from being formed between the opening 51 and the fixed portion 22a of the movable mold 22. The start of the core back is not limited to after the completion of the supply of the molten foamable resin 70 into the cavity 27 (after the completion of filling), but after the start of the supply of the molten foamable resin 70 into the cavity 27 and before the completion of the supply. (Before completion of filling) However, from the viewpoint of satisfactory foaming, it is preferable that the supply is after completion of the supply of the melt-foamable resin 70 into the cavity 27 (after completion of filling).

  When the melt-foamable resin 70b supplied into the second cavity portion 27b is cooled by natural cooling from the start of supply into the second cavity portion 27b, and the resin temperature reaches the solidification temperature, It solidifies (hardens) (the solidification temperature is reached after the completion of the core back). When the melt-foamable resin 70 is solidified in this way, foaming stops and the foamed cell diameter does not increase any further. The melt-foamable resin 70b supplied into the second cavity portion 27b becomes a main body portion 50a by solidifying.

  After completion of the core back, it waits for a predetermined time after the completion. During this time, the molten foamable resin 70b supplied into the second cavity portion 27b is completely solidified. Thus, as shown in FIGS. 4 and 8, the molding of the resin molded product 50 formed by solidifying the melt-foamable resin 70 is completed. The main body portion 50 a of the resin molded product 50 is formed with an opening 51 having a rectangular shape when viewed from the horizontal direction at a position corresponding to the fixed portion 22 a of the movable mold 22. The bottom wall 50b is formed at the end on the fixed mold 21 side. The bottom wall portion 50b closes all ends of the opening 51 on the fixed mold 21 side.

  Thereafter, the movable mold 22 is moved to the opposite side of the fixed mold 21 to perform mold opening, and the molded resin molded product 50 is taken out from the mold 4. Then, unnecessary portions of the resin molded product 50 including the bottom wall portion 50b are cut to complete the resin molded product 50.

-Effect-
As described above, according to the present embodiment, the molten foamable resin 70 is supplied into the first and second cavity portions 27a and 27b, so that the molten foamable resin 70a is supplied into the first cavity portion 27a. In addition, since the bottom wall portion 50b thinner than the thickness of the main body portion 50a is formed so as to be continuous with the molten foamable resin 70b supplied into the second cavity portion 27b, the bottom wall portion 50b opens the opening 51 outward. It is possible to suppress the spread to. Therefore, it can suppress that the magnitude | size of the opening part 51 of the resin molded product 50 becomes larger than a desired magnitude | size.

  Moreover, since the melt foamable resin 70 is simultaneously supplied into the first and second cavities 27a and 27b, the bottom wall 50b can be formed at an appropriate timing.

  Further, since the bottom wall portion 50b is formed so as to connect the opposing portions of the peripheral edge portion of the first cavity portion 27a in the melt-foamable resin 70b supplied into the second cavity portion 27b, It can suppress more reliably that the opening part 51 spreads outward by the wall part 50b.

  Furthermore, since only the movable portion 22b of the movable die 22 is moved to the opposite side of the fixed die 21, only the portion corresponding to the second cavity portion 27b of the molding die 4 is core-backed. Thus, the main body 50a having the opening 51 in which the bottom wall 50b is formed at the end on the fixed mold 21 side can be formed.

  In addition, since the melt-foamable resin 70 contains a physical foaming agent, the foaming ratio is increased. Therefore, if no measures are taken, the size of the opening 51 of the resin molded product 50 is desired. Although the situation tends to be larger than the size, according to the present embodiment, it can be suppressed. Furthermore, the average foamed cell diameter of the resin molded product 50 can be made relatively small, and the strength of the resin molded product 50 can be reliably improved.

  Furthermore, since the physical foaming agent is composed of a supercritical fluid, the foaming ratio is further increased. Therefore, if no measures are taken, the size of the opening of the resin molded product 50 is further desired. However, according to the present embodiment, it can be suppressed. Further, by utilizing the fact that the supercritical fluid has both viscosity and dissolving power as a liquid and intense molecular motion as a gas, the foam cell of the resin molded product 50 can be made ultrafine, and the resin molded product The strength of 50 can be improved even more reliably.

(Other embodiments)
In the above embodiment, the present invention is applied to form the opening 51 in the main body 50a of the resin molded product 50. However, as shown in FIGS. You may apply in forming the notch part 52. FIG. FIG. 9 shows a state before removal of the bottom wall 50b, and FIGS. 10 to 12 show a state after removal of the bottom wall 50b. The notch 52 in FIG. 9 is formed in a square shape. The notch 52 in FIG. 10 is formed in a trapezoidal shape, and the notch 52 is fitted and positioned with a trapezoidal protrusion 62 of the mating member 60. The cutout portion 52 in FIG. 11 is formed in a substantially T shape, and the cutout portion 52 in FIG. 12 is formed in a substantially L shape.

  Moreover, in the said embodiment, although the melt foamable resin 70 is simultaneously supplied in the 1st and 2nd cavity parts 27a and 27b, the melt foamable resin 70 is supplied in the 1st and 2nd cavity parts 27a and 27b. It may be supplied at different times. However, from the viewpoint of forming the bottom wall portion 50b at an appropriate timing, it is preferable to supply them simultaneously.

  Furthermore, in the said embodiment, although the bottom wall part 50b is formed so that all the circumference | surroundings may continue with the molten foamable resin 70b supplied in the 2nd cavity part 27b, it is not restricted to this. For example, as shown in FIGS. 13 and 14, a rectangular through hole 50c may be formed at the center of the bottom wall 50b. The through holes 50c may be arranged in parallel in the vertical and horizontal directions as shown in FIG. Moreover, as shown in FIG. 14, the through-hole 50c may be a long hole, and this may be arranged in parallel vertically or horizontally. Alternatively, as shown in FIGS. 15 and 16, the bottom wall portion 50b may be formed so that only a part of the periphery of the bottom wall portion 50b is continuous with the melt-foamable resin 70b supplied into the second cavity portion 27b. For example, as shown in FIG. 15, a rectangular through hole 50 c may be formed in the peripheral portion (corner portion in FIG. 15) of the bottom wall portion 50 b. In addition, as shown in FIG. 16, long hole-like through holes 50c may be arranged in parallel in the vertical or horizontal direction on the bottom wall portion 50b. In addition, the dashed-two dotted line of FIGS. 13-16 is an imaginary line which shows the boundary of the bottom wall part 50b and the molten foamable resin 70b supplied to the 2nd cavity part 27b. However, from the viewpoint of suppressing the size of the opening 51 of the resin molded product 50 from becoming larger than a desired size, it is preferable not to form the through hole 50c.

  Moreover, in the said embodiment, although the melt foamable resin 70 shall contain the physical foaming agent which consists of a supercritical fluid, as a foaming agent in the melt foamable resin 70, physical foaming agents other than a supercritical fluid are used. It is also possible to use a chemical foaming agent that generates a gas by a chemical reaction caused by heat, and may be one that dissolves in a molten resin or one that does not dissolve.

  Moreover, in the said embodiment, although the side surface of the fixing | fixed part 22a is extended in the core back direction, as long as it extends in a substantially core back direction, it is not restricted to this. For example, as shown in FIG. 17, it may extend so that it may spread outside as it goes to the fixed mold 21 side.

  The present invention is not limited to the embodiments, and can be implemented in various other forms without departing from the spirit or main features thereof.

  As described above, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is defined by the claims, and is not limited by the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  As described above, the method and apparatus for molding a resin molded product according to the present invention can be applied to uses such as suppressing the opening or notch of the resin molded product from becoming larger than a desired size.

1 is an overall schematic configuration diagram of a molding apparatus according to an embodiment of the present invention. It is a perspective view which shows the state at the time of use of the resin molded product in which the opening part was formed. It is the schematic which shows the state after completion of supply of the melt foamable resin in the cavity of a shaping | molding die in a shaping | molding apparatus. It is the schematic which shows the state after the completion of shaping | molding of the resin molded product in a shaping | molding apparatus. It is a principal part schematic diagram which shows the state after completion of supply to the cavity of molten foamable resin in a shaping | molding die. It is the schematic which shows the state at the time of the core back of a shaping | molding die in a shaping | molding apparatus. It is a principal part schematic diagram which shows the state at the time of a core back in a shaping | molding die. It is a principal part schematic diagram which shows the state after completion | finish of shaping | molding of the resin molded product in a shaping | molding die. It is a perspective view which shows the resin molded product in which the notch part was formed. It is a perspective view which shows the state at the time of use of the modification of the resin molded product in which the notch part was formed. It is a perspective view which shows another modification of the resin molded product in which the notch part was formed. It is a perspective view which shows another modification of the resin molded product in which the notch part was formed. It is a top view which shows the modification of a bottom wall part. It is a top view which shows another modification of a bottom wall part. It is a top view which shows another modification of a bottom wall part. It is a top view which shows another modification of a bottom wall part. It is a principal part schematic diagram which shows the modification of a shaping | molding die. It is a principal part block diagram of the conventional shaping | molding die, (a) shows the state before a core back, (b) shows the ideal state after shaping | molding of a resin molded product, (c) is resin The actual state after completion of the molding of the molded product is shown. It is a principal part top view of the conventional resin molded product in which the opening part was formed. It is a principal part top view of the conventional resin molded product in which the notch part was formed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Molding apparatus 4 Mold 7 Resin supply apparatus (supply means)
21 fixed mold 22 movable mold 22a fixed section 22b movable section 27 cavity 27a first cavity section 27b second cavity section 50 resin molded product 50a main body section 50b bottom wall section 51 opening section 52 notch section 70 melt foamable resin 70a first Melt foamable resin 70b supplied into the cavity part Melt foamable resin supplied into the second cavity part

Claims (11)

The melt-foamable resin is supplied into a cavity of a mold composed of a fixed mold and a movable mold, and the mold is core-backed to foam the melt-foamable resin supplied into the cavity. A resin molded product molding method for molding a resin molded product comprising a body portion having a portion or a notch,
The cavity includes a first cavity formed at a position corresponding to the opening or the notch, and a second cavity formed at a position corresponding to a portion other than the opening or the notch in the main body. And consists of
By supplying the melt-foamable resin into the first and second cavity portions, the bottom wall portion made of the melt-foamable resin supplied into the first cavity portion and thinner than the thickness of the main body portion is formed in the first and second cavity portions. 2 formed in a continuous manner with the melt-foamable resin supplied into the cavity portion, and melt-foamed into the second cavity portion by core-backing only the portion corresponding to the second cavity portion of the mold. A method for molding a resin molded product, comprising forming a main body having an opening or a notch in which the bottom wall is formed at an end on the fixed mold side by foaming all of the resin. In the molding method of the resin molded product according to claim 1,
A method for molding a resin molded product, wherein the melt-foamable resin is simultaneously supplied into the first and second cavities. In the molding method of the resin molded product according to claim 1 or 2,
The bottom wall portion is formed so as to connect mutually facing portions of the peripheral edge portion of the first cavity portion in the melt-foamable resin supplied into the second cavity portion. Molding method. In the molding method of the resin molded product according to any one of claims 1 to 3,
The method for molding a resin molded product, wherein the melt-foamable resin contains a physical foaming agent. In the molding method of the resin molded product according to claim 4,
The said physical foaming agent consists of supercritical fluids, The molding method of the resin molded product characterized by the above-mentioned. A mold comprising a fixed mold and a movable mold; and a supply means for supplying a melt-foamable resin into the cavity of the mold, and the melt-foamable resin is supplied into the cavity by the supply means. A resin molded product for molding a resin molded product having a main body having an opening or a notch by causing the mold to core back and foaming the melt-foamable resin supplied into the cavity. A molding device,
The cavity includes a first cavity formed at a position corresponding to the opening or the notch, and a second cavity formed at a position corresponding to a portion other than the opening or the notch in the main body. And consists of
By supplying the molten foamable resin into the first and second cavity portions by the supply means, the bottom wall is made of the molten foamable resin supplied into the first cavity portion and is thinner than the thickness of the main body portion. A portion is formed so as to be continuous with the melt-foamable resin supplied into the second cavity portion, and only a portion corresponding to the second cavity portion of the molding die is core-backed and supplied into the second cavity portion. A resin molded product characterized by forming a main body having an opening or a notch in which the bottom wall is formed at an end on the fixed mold side by foaming all of the melt-foamable resin that is formed Molding equipment. In the molding apparatus of the resin molded product according to claim 6,
The apparatus for molding a resin molded product, wherein the supply means is configured to simultaneously supply the melt-foamable resin into the first and second cavities. In the shaping | molding apparatus of the resin molded product of Claim 6 or 7,
The molding die is configured such that the bottom wall portion is formed so as to connect mutually facing portions of the peripheral edge portion of the first cavity portion in the melt-foamable resin supplied into the second cavity portion. An apparatus for molding a resin molded product. In the shaping | molding apparatus of the resin molded product as described in any one of Claims 6-8,
The movable mold is disposed at a position corresponding to the first cavity portion, and has a fixed portion having a side surface extending substantially in the core back direction, and a movable portion disposed at a position corresponding to the second cavity portion. Consists of
A resin molded product characterized in that only the portion of the molding die corresponding to the second cavity portion is core-backed by moving only the movable portion of the movable die to the side opposite to the fixed die. Molding equipment. In the shaping | molding apparatus of the resin molded product as described in any one of Claims 6-9,
The apparatus for molding a resin molded product, wherein the melt-foamable resin contains a physical foaming agent. In the molding apparatus of the resin molded product according to claim 10,
The apparatus for molding a resin molded product, wherein the physical foaming agent comprises a supercritical fluid.

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