JP2009061592A - Method of molding foamed resin molded article and molding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of foaming in a foaming suppression resin section due to the drop of a resin pressure caused by the core back of a movable core during molding of foamed resin molded articles. <P>SOLUTION: The method of molding the foamed resin molded articles uses a mold including the movable core 32 permitting a core back and used for forming a porous resin portion where air bubbles have grown of the foamed resin molded article and an immobile core 33 for forming the foaming suppression resin portion where the growth of the air bubbles is suppressed of the foamed resin molded article, and the method includes: filling foamable resin R of a molten state into a cavity of the mold; and performing the core back of the movable core 32 in the direction where the volume of the cavity 42 expands, wherein the core back is performed in a state (code g) where the spacing between a cavity forming surface 33c of the immobile core 33 and a cavity forming surface 31c facing the cavity forming surface 33c of the immobile core 33 is narrowed in the peripheral edge of the cavity forming surface 33c of the immobile core 33. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a molding method and a molding apparatus for a foamed resin molded article, and belongs to the technical field of resin molding.

  Conventionally, resin molded products manufactured by injection molding or the like using ABS (acrylonitrile, butadiene, styrene) resin, PP (polypropylene) resin, or the like as materials are used for automobile parts and the like. In that case, from the viewpoints of heat insulation, lightness, shock absorption, etc., resin molded products, for example, bubbles are generated in the resin using a physical foaming agent such as carbon dioxide or nitrogen or a chemical foaming agent such as sodium hydrogen carbonate. It may be a foamed resin molded article having a porous structure. Such a foamed resin molded product generally has a direction in which the volume of the cavity expands after filling a moldable cavity with a molten foamable resin (an unfoamed resin containing an unfoamed foaming agent). It is manufactured by core-backing the mold.

  By the way, such a foamed resin molded product may be fastened to, welded to, or matched with other resin parts or metal parts (fit or sandwich). At this time, it is desirable that the fastening portion, the welded portion, the mating portion, and the like of the foamed resin molded product are non-foamed or low-foamed foam-suppressing resin portions in which foaming is suppressed. Otherwise, since the strength of the porous resin part in which bubbles have grown is relatively weak, for example, when the fastening part is fastened by a fastener such as a bolt, the fastening part may be buckled or cracked. Because. For the same reason, for example, when force is applied to the welded portion after welding, the welded portion may be deformed or dropped. Further, for the same reason, for example, when a force is applied to the mating portion after the mating, the mating portion may be deformed or dropped. Furthermore, for the mating part, the porous resin part in which bubbles have grown has a relatively low dimensional accuracy due to sink marks or the like at the time of the core back. This is because it may occur.

  Therefore, in order to manufacture a foamed resin molded product having the fastening portion, the welded portion, the mating portion, and the like as described above, most of the foamed resin molded product is a porous resin portion in which bubbles have grown. It is necessary to manufacture a foamed resin molded article having a configuration in which the foaming suppression resin part in which the suppression is partially present.

  For this purpose, for example, it is proposed to apply the technique described in Patent Document 1. That is, as illustrated in FIG. 12A, the mold is composed of a fixed mold for clamping and opening and a movable mold, and the movable mold is a porous material in which bubbles are grown in the foamed resin molded product. A movable core that can be core-backed to form a resin part, and a stationary core to form a foam-suppressed resin part in which foam growth is suppressed among foamed resin molded products, and these fixed molds After filling the foamed resin in a molten state into the cavity formed by the movable core and the stationary core, the movable core is core-backed in the direction in which the volume of the cavity expands (see the white arrow in the figure).

  Alternatively, as illustrated in FIG. 13A, the stationary core can be disposed on the fixed mold side. However, in this case, the stationary core is also moved in the same direction and at the same speed together with the core back of the movable core so that the gap between the cavity forming surface of the movable core and the cavity forming surface of the stationary core facing each other is not widened. Required (see white arrow in the figure).

  Then, in any case, the portion of the foamable resin filled in the cavity by the core back of the movable core (in other words, the portion not shaped by the stationary core) of the foamable resin filled in the cavity is made of resin. As a result, the foaming agent contained in the foamable resin starts to foam and bubbles grow, and the porosity is relatively large (in other words, the resin density is relatively small). It becomes the quality resin part. On the other hand, the portion of the foamable resin filled in the cavity that is shaped by the stationary core that does not core back does not drop the pressure of the resin, and as a result, the foaming agent does not start foaming and bubbles grow. In other words, the foaming suppression resin portion has a relatively small porosity (in other words, a relatively high resin density).

JP-A-11-156881 (paragraph 0031)

  However, as described above, the present inventors use a mold including a movable core and an immovable core as described above to produce a foamed resin molded product having a configuration in which the porous resin portion and the foam suppression resin portion coexist. As a result of repeated research, it was found that the foaming agent started to foam and bubbles would grow at the peripheral edge of the cavity forming surface of the stationary core among the parts of the foamable resin shaped by the stationary core. I found out. As illustrated in FIGS. 12B and 13B, this is because the cavity formed by the movable core and the stationary core or the cavity formed by the stationary mold and the stationary core is continuous. The effect of the resin pressure drop that occurs in the part that is shaped in the case extends to the part that is shaped in the stationary core, and as a result, the core of the foam cell contained in the part shaped in the stationary core is the movable core. Because the foaming agent starts to foam at the peripheral edge of the cavity forming surface of the stationary core adjacent to the movable core or adjacent to the fixed mold (see the black arrow in the figure). It is thought that.

  Therefore, the portion formed by the stationary core does not all become the foam suppression resin portion, and the porosity of the portion formed by the peripheral portion of the cavity forming surface of the stationary core among the portions shaped by the stationary core. Becomes larger than the porosity of the other parts (in other words, the resin density is reduced), and as a result, the part formed by the immobile core is completely connected to the fastening part and the welding part as described above. When used as a mating portion, the above-described problems such as buckling, cracking, deformation, dropout, and backlash occur.

  An object of the present invention is to cope with the above-described problems, and an object of the present invention is to suppress foaming from occurring in the foam suppression resin portion due to a decrease in resin pressure accompanying the core back of the movable core.

  In order to solve the above problems, the present invention uses the following means.

  That is, in the invention according to claim 1 of the present application, after filling the foamed resin in the molten state into the cavity of the mold, a part of the mold is core-backed in the direction in which the volume of the cavity expands to expand the foamed resin. A method for molding a molded product, wherein a movable core capable of core back for forming a porous resin part in which bubbles are grown in a foamed resin molded product and growth of bubbles in the foamed resin molded product are suppressed. Using a mold including a stationary core for forming the foam suppression resin portion, a filling step of filling a molten foamable resin into a cavity of the mold, and after the filling step, the volume of the cavity is A core back step of core-backing the movable core in an expanding direction, and in the core back step, a gap between the cavity forming surface of the stationary core and the cavity forming surface facing the cavity forming surface is set. While narrowed at the periphery of the cavity-forming surface of the stationary core, characterized in that the movable core core back.

  Next, the invention described in claim 2 of the present application is the method for molding a foamed resin molded product according to claim 1, wherein in the core back step, the interval between the cavity forming surfaces is set to a cavity of a stationary core. It is characterized by being narrowed intermittently at the periphery of the forming surface.

  Next, the invention according to claim 3 of the present application is the method for molding a foamed resin molded article according to claim 1 or 2, wherein the peripheral portion of the cavity forming surface of the stationary core is formed on the opposite cavity forming surface. The portion corresponding to the peripheral edge of the stationary core cavity forming surface among the stationary core protruding by a predetermined amount toward the cavity and / or the cavity forming surface facing the cavity forming surface of the stationary core is the cavity forming surface of the stationary core. By using a mold projecting by a predetermined amount toward the core, the gap between the cavity forming surfaces is narrowed at the periphery of the cavity forming surface of the stationary core in the core back step.

  Next, the invention according to claim 4 of the present application is the method for molding a foamed resin molded article according to any one of claims 1 to 3, wherein the foamable resin in a molten state contains a physical foaming agent. It is characterized by containing.

  Next, the invention according to claim 5 of the present application is the method for molding a foamed resin molded article according to claim 4, wherein the physical foaming agent is a fluid in a supercritical state.

  On the other hand, in the invention according to claim 6 of the present application, after filling the foamed resin in the molten state into the cavity of the mold, a part of the mold is core-backed in the direction in which the volume of the cavity is expanded, An apparatus for molding a molded product, in which a movable core that can be core-backed to form a porous resin part in which bubbles have grown in a foamed resin molded product, and the growth of bubbles in the foamed resin molded product are suppressed. A mold including a stationary core for forming the foam-inhibiting resin portion; a filling means for filling a molten foamable resin into a cavity of the mold; and a volume of the cavity after filling by the filling means Core back means for core-backing the movable core in the direction in which the core expands, and when the core back is performed by the core back means, the cavity forming surface of the stationary core and the cavity forming opposite to the cavity forming surface The distance between, characterized in that it includes a gap adjusting means to narrow the peripheral portion of the cavity-forming surface of the stationary core.

  Next, the invention according to claim 7 of the present application is the molding apparatus for the foamed resin molded product according to claim 6, wherein the interval adjusting means sets the interval between the cavity forming surfaces to the cavity of the stationary core. It is characterized by being narrowed intermittently at the periphery of the forming surface.

  Next, the invention according to claim 8 of the present application is the foamed resin molded product molding apparatus according to claim 6 or 7, wherein the gap adjusting means includes a peripheral portion of the cavity forming surface of the stationary core, The protrusion that protrudes by a predetermined amount toward the opposite cavity forming surface and / or the portion of the cavity forming surface that faces the cavity forming surface of the stationary core that corresponds to the peripheral edge of the cavity forming surface of the stationary core is stationary. It is comprised by the protrusion part which protruded only predetermined amount toward the cavity formation surface of the core, It is characterized by the above-mentioned.

  Next, the invention according to claim 9 of the present application is the molding apparatus for the foamed resin molded product according to any one of claims 6 to 8, wherein the foaming in a molten state is performed before filling by the filling means. A physical foaming agent supply means for supplying a physical foaming agent to the functional resin is provided.

  Next, the invention according to claim 10 of the present application is the molding apparatus for the foamed resin molded product according to claim 9, wherein the physical foaming agent supply means supplies a fluid in a supercritical state as the physical foaming agent. It is characterized by doing.

  First, according to the invention of claim 1 or claim 6, after filling the mold cavity with the molten foamable resin, a part of the mold is core-backed in the direction in which the volume of the cavity increases. In the method of molding a foamed resin molded product, a mold including a movable core for forming the porous resin portion and a stationary core for forming the foam suppression resin portion is used. After filling the molten foamable resin, the movable core is core-backed in the direction in which the volume of the cavity expands, so a foamed resin molded product having a configuration in which the porous resin portion and the foam suppression resin portion coexist is obtained. Will be manufactured.

  In addition, the core back of the movable core has a cavity-forming surface of the stationary core and a cavity-forming surface opposite to the cavity-forming surface (for example, when the stationary core is disposed on the movable mold side, as shown in FIG. As illustrated, it is a fixed cavity forming surface, and conversely, when the stationary core is arranged on the fixed mold side, as illustrated in FIG. And the gap between the cavity forming surface of the stationary core is narrowed at the periphery of the cavity forming surface of the stationary core. As a result, the drag force that the core of the foam cell contained in the portion shaped by the stationary core is dragged to the side shaped by the movable core can be reduced. Due to core-back due to the reduction of the resin pressure it becomes possible to suppress foaming from occurring in the foam control resin of.

  In this case, according to the invention described in claim 2 or claim 7, the interval between the cavity forming surfaces is intermittently narrowed at the peripheral edge portion of the cavity forming surface of the stationary core. It is possible to suppress a decrease in the rigidity of the portion formed at the peripheral edge portion of the cavity forming surface of the core.

  That is, the space formed between the cavity forming surfaces is narrowed at the periphery of the cavity forming surface of the stationary core, and the portion formed at the periphery of the cavity forming surface of the stationary core becomes a recess. As a result, the thickness of the molded product is reduced, and as a result, there is a concern about a decrease in rigidity of the portion. However, by intermittently narrowing the gap between the cavity forming surfaces, the recesses are formed intermittently, The boundary between the locations exhibits a function as a rib, and the rigidity is improved as compared with the case where the recesses are continuously formed. As a result, the thickness of the molded product of the portion is reduced. The disadvantage that has become is suppressed.

  Next, according to the invention described in claim 3 or claim 8, by using the stationary core in which the peripheral edge portion of the cavity forming surface of the stationary core protrudes by a predetermined amount toward the opposing cavity forming surface, and / Or use a mold in which a portion corresponding to the peripheral edge of the cavity forming surface of the stationary core out of the cavity forming surface facing the cavity forming surface of the stationary core protrudes by a predetermined amount toward the cavity forming surface of the stationary core. Thus, since the interval between the cavity forming surfaces is narrowed at the peripheral edge portion of the cavity forming surface of the stationary core, a restriction can be provided in the cavity at the peripheral edge portion of the cavity forming surface of the stationary core with a simple configuration. It becomes possible.

  In addition, as another structure which narrows the space | interval between the said cavity formation surfaces in the peripheral part of the cavity formation surface of a stationary core, for example, prior to the core back of a movable core, it opposes from the peripheral part of the cavity formation surface of a stationary core. The plate member is advanced by a predetermined amount toward the cavity forming surface, or the portion of the cavity forming surface facing the cavity forming surface of the stationary core is fixed from the portion corresponding to the peripheral portion of the cavity forming surface of the stationary core. For example, the plate member may be advanced by a predetermined amount toward the cavity forming surface of the core.

  Next, according to the invention described in claim 4 or claim 9, since the physical foaming agent is contained in the molten foamable resin, for example, the foaming pressure is higher than that of a chemical foaming agent or the like. In addition, the drag force can be reduced while the phenomenon that the core of the foam cell contained in the portion shaped by the stationary core is dragged to the side shaped by the movable core is more likely to occur. In addition, by using a physical foaming agent, the foamed cell diameter inside the foamed resin molded product can be made relatively small, and the physical properties such as rigidity of the foamed resin molded product can be improved. It becomes.

  In that case, according to the invention described in claim 5 or claim 10, since the supercritical fluid is contained in the molten foamable resin, the drag phenomenon is more likely to occur. However, the drag force can be reduced, and by using a fluid in a supercritical state, the foamed cell diameter inside the foamed resin molded product can be made even finer. It is possible to further improve physical properties such as rigidity. Hereinafter, the present invention will be described in more detail through the best mode for carrying out the invention.

  FIG. 1 is an overall configuration diagram of a molding apparatus 10 for a foamed resin molded product according to the best embodiment of the present invention, showing a filling process, and FIG. 2 shows a core back process. The molding apparatus 10 includes an injection machine 20 and a molding die 30.

  The injection machine 20 (corresponding to “filling means” in the scope of the claims) injects a molten foamable resin R containing a physical foaming agent into the cavity 42 of the mold 30 in a clamped state. A supercritical fluid as a physical foaming agent for a hopper 21 for introducing a base resin such as ABS resin into the cylinder and a molten base resin kneaded in the cylinder. And a nozzle 24 for supplying. A fluid in a supercritical state is generated from a cylinder 22 of an inert gas such as carbon dioxide or nitrogen through a supercritical fluid generator 23. Thereby, the foamable resin R in a molten state in which the physical foaming agent is contained in the base resin is obtained. The foamable resin R is injected into the cavity 42 of the mold 30 in a clamped state through a supply passage 41 formed in the fixed mold 31.

  The inert gas cylinder 22, the supercritical fluid generator 23, and the supercritical fluid supply nozzle 24 correspond to “physical foaming agent means” in the scope of the claims.

  Here, the fluid in a supercritical state is a fluid that exceeds a limit temperature (critical temperature) and pressure (critical pressure) at which gas and liquid can coexist, and the critical temperature is, for example, carbon dioxide The critical pressure is, for example, 7.4 MPa for carbon dioxide and 3.4 MPa for nitrogen. A fluid in a supercritical state has a density close to that of a liquid and has a fluidity similar to that of a gas. As a result, the resin moves actively in the base resin in a molten state, and diffuses and penetrates even deeply into the resin molecule, and can become a seed or nucleus of fine foaming.

  The mold 30 includes a fixed mold 31 and movable molds 32 and 33 that clamp and open each other. The movable type includes a movable core 32 that can be core-backed in a direction in which the volume of the cavity 42 increases, and a stationary core 33. The movable core 32 is for forming a porous resin part C (see FIG. 7) in which bubbles grow out of the foamed resin molded product 50 (see FIG. 3) described below. The immobile core 33 is for forming the foam suppression resin part A (see FIG. 7) in the foamed resin molded product 50 in which the growth of bubbles is suppressed.

  FIG. 3 is a front view of the foamed resin molded product 50 according to the present embodiment as viewed from the movable molds 32 and 33 side. The foamed resin molded product 50 is an automobile part and constitutes a door together with the inner panel 60 and the outer panel 70 as shown in FIG. In that case, the foamed resin molded product 50 is fastened to the metal inner panel 60. Therefore, the some fastening part 51 ... 51 is scattered in the peripheral part of the foamed resin molded product 50. FIG. The foamed resin molded product 50 is covered with a door trim (not shown).

  5A is an enlarged view of the fastening portion 51 of the foamed resin molded product 50 as viewed from the arrow V side in FIG. 4, and FIG. 5B is along the VI-VI line in FIG. 5A. It is sectional drawing. As shown in the figure, the fastening portion 51 is configured by a circular recess. Therefore, the portion of the foamed resin molded product 50 other than the fastening portion 51 has a relatively large thickness, and the bottom portion of the fastening portion 51 has a relatively small thickness. And the hole 51a is formed in the bottom part of this fastening part 51, and the foamed resin molded product 50 is fastened with the inner panel 60 with the volt | bolt 80 and the nut 90 through this hole 51a.

  FIG. 6 is an enlarged view of a main part of the molding die 30 for showing the molding operation of the foamed resin molded product 50 in stages.

  First, as shown in FIG. 6A, the fixed mold 31 and the movable mold (the movable core 32 and the non-moving core 33) are clamped. Here, the stationary core 33 is provided with a protruding portion 33 a for forming the hole 51 a of the fastening portion 51. Then, the projecting portion 33 a abuts on the fixed mold 31, whereby a cavity 42 is formed by the fixed mold 31, the movable core 32, and the stationary core 33.

  Next, as shown in FIG. 6B, the molten foamable resin R is filled into the cavity 42 by the injection machine 20 (filling step).

  Next, as shown in FIG. 6C, after the foamable resin R is filled into the cavity 42, the core back of the movable core 32 is started in the direction in which the volume of the cavity 42 increases (see the white arrow in the figure). ).

  Next, as shown in FIG. 6D, when the movable core 32 is core-backed by a predetermined amount, the core-back of the movable core 32 is finished.

  Although not shown, for example, a hydraulic device for core-backing the movable core 32 is provided, which corresponds to “core-back means” in the scope of the claims.

  In this core back process, when the movable core 32 cores back, the portion of the foamable resin R filled in the cavity 42 that is shaped by the movable core 32 has a reduced pressure of the resin R. As a result, The foaming agent contained in the foamable resin R (in this case, a fluid in a supercritical state) starts to foam and bubbles grow, and as shown in FIG. 7, the porosity is relatively large (in other words, The resin density is relatively small).

  On the other hand, the portion of the foamable resin R filled in the cavity 42 that is shaped by the stationary core 33 that does not core back does not lower the pressure of the resin R, and as a result, the foaming agent does not start foaming. Bubbles do not grow, and as shown in FIG. 7, the foam suppression resin portion A has a relatively low porosity (in other words, a relatively high resin density).

  However, in this case, since the cavity 42 formed by the movable core 32 and the stationary core 33 is continuous, the effect of the resin pressure drop generated in the portion shaped by the movable core 32 is shaped by the stationary core 33. As a result, the core of the foamed cell contained in the portion shaped by the stationary core 33 is dragged toward the portion shaped by the movable core 32, so that the movable core 33 and the stationary core 33 are movable. There is a concern that the foaming agent starts to foam and bubbles grow in the vicinity of the boundary with the core 32, that is, at the peripheral edge portion of the cavity forming surface 33c (see FIG. 6A) of the stationary core 33 adjacent to the movable core 32. There is.

  Thus, in the present embodiment, as shown in an enlarged circle in the broken line in FIG. 6A, the peripheral edge portion of the cavity forming surface 33c of the stationary core 33 faces the cavity forming surface 31c of the fixed mold 31 that faces the fixed core 31. A fixed core 33 protruding by a predetermined amount, that is, a protruding portion 33b protruding from the peripheral portion of the cavity forming surface 33c of the fixed core 33 by a predetermined amount toward the cavity forming surface 31c of the opposed fixed mold 31 (claims) In this core back step, the cavity forming surface 33c of the stationary core 33 and the cavity forming surface 31c opposite to the cavity forming surface 33c are used. The gap between the movable core 32 and the movable core 32 is reduced at the peripheral edge of the cavity forming surface 33c of the stationary core 33 (see reference numeral a). It is intended to click.

  As a result, as shown in FIG. 7, the portion formed by the protruding portion 33 b at the peripheral edge portion of the cavity forming surface 33 c of the stationary core 33 becomes a recess (concave groove) 51 b, and the foamed resin molded product 50 is formed. The thickness is reduced. This portion is referred to as “intermediate resin portion B” for convenience in the present embodiment.

  In the present embodiment, since the protruding portion 33b is continuously provided at the peripheral edge portion of the cavity forming surface 33c of the stationary core 33, the recess (concave groove) 51b or the intermediate resin portion B is shown in FIG. As described above, the foam suppression resin portion A is continuous in the circumferential direction around the foam suppression resin portion A so as to be isolated from the porous resin portion C.

  And the head of the volt | bolt 80 is seated on the bottom part of the fastening part 51 within the range of the said foam suppression resin part A (refer FIG.5 (b)). That is, the head of the bolt 80 does not apply a fastening force with the inner panel 60 to the recess (concave groove) 51b or the intermediate resin portion B.

  Thus, in this embodiment, after filling the foamed resin R in the molten state into the cavity 42 of the mold 30, a part of the mold (movable core 32) is placed in the direction in which the volume of the cavity 42 increases. A method of molding the foamed resin molded product 50 by core back is provided.

  In that case, a mold 30 including a movable core 32 for forming the porous resin portion C and a stationary core 33 for forming the foam suppression resin portion A is used and melted in the cavity 42 of the mold 30. After filling the foamable resin R in the state, the movable core 32 is core-backed in the direction in which the volume of the cavity 42 is expanded, so that the foaming of the configuration in which the porous resin portion C and the foam suppression resin portion A coexist. The resin molded product 50 is manufactured.

  In addition, the core back of the movable core 32 has an interval between the cavity forming surface 33c of the stationary core 33 and the cavity forming surface 31c of the fixed mold 31 facing the cavity forming surface 33c. Since it is performed in a state where it is narrowed at the peripheral edge (see symbol (a) in FIG. 6A), a diaphragm is provided in the cavity 42 at the peripheral edge of the cavity forming surface 33c of the stationary core 33. As a result, The drag force that the core of the foam cell contained in the portion shaped by the stationary core 33 is dragged to the side shaped by the movable core 32 can be reduced, and the core back of the movable core 32 can be reduced. It is possible to suppress foaming from occurring in the foam suppression resin portion A due to the accompanying decrease in the resin pressure.

  In that case, by using the stationary core 33 in which the peripheral edge portion of the cavity forming surface 33c of the stationary core 33 protrudes by a predetermined amount toward the cavity forming surface 31c of the opposed fixed mold 31, that is, the cavity of the stationary core 33 By using a stationary core 33 having a projecting portion 33b (see FIG. 6A) projecting a predetermined amount toward the cavity forming surface 31c of the opposed fixed mold 31 at the peripheral portion of the forming surface 33c, the cavity is formed. Since the space between the surfaces 33c and 31c is narrowed at the peripheral edge portion of the cavity forming surface 33c of the stationary core 33, it is reduced in the cavity 42 at the peripheral edge portion of the cavity forming surface 33c of the stationary core 33 with a simple configuration. Can be provided.

  As another configuration in which the space between the cavity forming surfaces 33c and 31c is narrowed at the peripheral edge portion of the cavity forming surface 33c of the stationary core 33, for example, the cavity 42 is formed on the peripheral edge portion of the cavity forming surface 33c of the stationary core 33. In contrast, the plate member includes a plate member that can be moved forward and backward, and from the peripheral portion of the cavity forming surface 33c of the stationary core 33 toward the cavity forming surface 31c of the opposed fixed mold 31 prior to the core back of the movable core 32. Or a plate member that can be moved back and forth with respect to the cavity 42 in a portion corresponding to the peripheral edge of the cavity forming surface 33c of the stationary core 33 in the cavity forming surface 31c of the fixed mold 31. In advance of the core back of the movable core 32, the portion is directed from the portion toward the cavity forming surface 33c of the stationary core 33. Te, can be or is advanced to the plate member by a predetermined amount.

  Moreover, since the foaming resin R in the molten state contains a physical foaming agent, for example, the foaming pressure is higher than that of a chemical foaming agent or the like. While the phenomenon in which the core of the resin is dragged toward the movable core 32 is more likely to occur, the drag force can be reduced and the foamed cell diameter inside the foamed resin molded product 50 can be reduced by using a physical foaming agent. Can be made to have a relatively small diameter, and physical properties such as rigidity of the foamed resin molded product 50 can be improved.

  In this case, since the fluid in the supercritical state is used as the physical foaming agent, the drag force can be reduced while the drag phenomenon is more likely to occur, and the fluid in the supercritical state is used. As a result, the foamed cell diameter inside the foamed resin molded product 50 can be made even finer, and physical properties such as rigidity of the foamed resin molded product 50 can be further improved.

  The molten foamable resin R may further contain reinforcing fibers such as glass fibers. The physical properties such as the strength of the foamed resin molded product 50 can be improved, and when the movable core 32 is core-backed, a springback phenomenon of the reinforcing fiber occurs, which causes foaming or expansion of the foamable resin R. The advantage of being further promoted is obtained.

  Although the specific example demonstrated above was an example which provided the protrusion part 33b in the peripheral part of the cavity formation surface 33c of the stationary core 33 as shown to Fig.9 (a), it is not restricted to this, According to a condition. As shown in FIG. 9 (b), a portion of the cavity forming surface 31 c of the fixed mold 31 that faces the cavity forming surface 33 c of the stationary core 33 is fixed to a portion corresponding to the peripheral portion of the cavity forming surface 33 c of the stationary core 33. A protruding portion 31b protruding by a predetermined amount toward the cavity forming surface 33c of the core 33 may be provided, or as shown in FIG. 9C, the protruding portion 33b is provided on both the stationary core 33 and the fixed mold 31. , 31b may be provided.

  Further, in the specific example described above, as shown in FIGS. 7 and 8, one relatively narrow groove (recess) 51 b has an annular shape around the foam suppression resin portion A in the circumferential direction. However, the present invention is not limited to this, and depending on the situation, as shown in FIG. 10 (a), there may be a plurality of grooves (recesses) 51b ... 51b in the inner and outer directions, Further, as shown in FIG. 10B, the width of the concave groove (recess) 51b can be made relatively wide.

  Or as shown in FIG.10 (c), the ditch | groove (recess) 51b ... 51b may be formed intermittently. In this case, by intermittently reducing the distance between the cavity forming surfaces 33c and 31c, the concave grooves (recesses) 51b... 51b are formed intermittently, and between the concave grooves (recesses) 51b and 51b. As a result, the boundary between the two has a function as a rib, and the rigidity is improved compared to the case where the concave groove (recess) 51b is continuously formed. As a result, in the intermediate resin portion B, The disadvantage that the thickness of the foamed resin molded product 50 is reduced is suppressed.

  Accordingly, as shown in FIG. 10 (d), when a plurality of grooves (recesses) 51b ... 51b are provided in the inner and outer directions, and further, grooves (recesses) 51b ... 51b are formed intermittently. The ribs at the boundary between the concave grooves (recesses) 51b and 51b are arranged in a wide range, and the rigidity is further improved (in the example shown in the figure, the phase of the ribs is further shifted, so that the rigidity is further improved. There is expected).

  Further, as shown in FIG. 10 (e), the grooves (recesses) 51b... 51b may be formed intermittently after the grooves (recesses) 51b. it can.

  The specific example described above is an example in which the stationary core 33 is arranged on the movable side as shown in FIGS. 1 and 2. However, the present invention is not limited to this, and depending on the situation, FIG. As shown in (a) and (b), the stationary core 33 can be disposed on the fixed mold 31 side. However, in this case, the gap between the cavity forming surface of the movable core 32 and the cavity forming surface of the stationary core 33 facing each other is not widened (in other words, the movable core 32 and the stationary core 33 that are in contact with each other) A feature is that, together with the core back of the movable core 32, the stationary core 33 is also moved in the same direction at the same speed (see the white arrow in the figure).

  The above embodiment is the best embodiment of the present invention, but it goes without saying that various modifications and changes may be made without departing from the scope of the claims.

  For example, instead of the fastening portion 51, a welded portion that is welded to the mating member, or a mating portion that is mated with the mating member (such as fitting or pinching) can be used.

  As described above in detail with reference to specific examples, in the present invention, during the molding of the foamed resin molded product, foaming occurs in the foam suppression resin portion due to a decrease in the resin pressure accompanying the core back of the movable core. Therefore, a wide range of industrial applicability is expected in the technical field of resin molding.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram of the shaping | molding apparatus of the foamed resin molded product which concerns on the best embodiment of this invention, Comprising: The filling process is shown. Similarly, a core back process is shown. It is a front view from the movable mold side of the foamed resin molded product shape | molded with the said shaping | molding apparatus. It is a longitudinal cross-sectional view which follows the IV-IV line | wire of FIG. 3, Comprising: A foamed resin molded product shows the state fastened with other components. (A) is an enlarged view of the fastening part of the foaming resin molded product seen from the arrow V side of FIG. 4, (b) is sectional drawing which follows the VI-VI line of FIG. 5 (a). It is the principal part enlarged view of the shaping | molding die for showing the shaping | molding operation | movement of the said shaping | molding apparatus in steps, Comprising: (a) shows the state which the fixed mold | type and the movable mold clamped, (b) is a shaping | molding. A state in which the mold cavity is filled with a foamable resin in a molten state, (c) is a state in which the core back of the movable core is started after filling the foamable resin, and (d) is a movable core This shows a state in which the core back is finished. It is an expanded sectional view similar to FIG.5 (b) for showing the fastening part of the foamed resin molded product shape | molded by the said shaping | molding operation | movement, and its periphery structure. Similarly, it is an enlarged front view similar to FIG. It is a principal part enlarged view similar to Fig.6 (a) which shows the modification of a protrusion part. It is a front view similar to FIG. 8 which shows the modification of a ditch | groove (recess). It is a fragmentary view similar to FIG.1 and FIG.2 which shows the modification of arrangement | positioning of a stationary core. It is explanatory drawing of the subject which this invention tends to solve, Comprising: (a) shows the state which is made into an ideal, (b) shows the state containing the conventional malfunction. It is another explanatory drawing of the subject which the present invention is going to solve, and (a) shows the ideal state and (b) shows the state containing the conventional fault.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Molding apparatus 20 Injection machine 30 Mold 31 Fixed mold 32 Movable core 33 Immovable core 33b Protruding part 33c Cavity formation surface 42 Cavity 50 Foamed resin molded product 51 Fastening part 60 Inner panel 80 Bolt 90 Nut A Foaming suppression resin part B Intermediate resin Part C Porous resin part R Expandable resin

Claims (10)

A method of molding a foamed resin molded product by filling a molten foamable resin into a cavity of a mold and then core-backing a part of the mold in a direction in which the volume of the cavity expands,
A movable core that can be core-backed to form a porous resin part in which foam has grown in a foamed resin molded product, and an immobilization to form a foam-inhibited resin part in which foam growth is suppressed in the foamed resin molded product. Using a mold that includes a core,
A filling step of filling a molten foamable resin into the cavity of the mold;
A core back step of core back the movable core in a direction in which the volume of the cavity expands after the filling step;
In the core back step, the movable core is core-backed in a state in which the gap between the cavity forming surface of the stationary core and the cavity forming surface facing the cavity forming surface is narrowed at the peripheral edge of the cavity forming surface of the stationary core. A method for molding a foamed resin molded product. A method for molding a foamed resin molded article according to claim 1,
In the core back step, the space between the cavity forming surfaces is intermittently narrowed at the peripheral edge portion of the cavity forming surface of the stationary core. A method for molding a foamed resin molded product according to claim 1 or 2,
Cavity formation of the stationary core of the stationary core in which the peripheral edge of the cavity forming surface of the stationary core protrudes by a predetermined amount toward the opposing cavity forming surface and / or the cavity forming surface facing the cavity forming surface of the stationary core By using a mold in which a portion corresponding to the peripheral edge of the surface protrudes by a predetermined amount toward the cavity forming surface of the stationary core, the space between the cavity forming surfaces is formed in the core back step by forming a cavity of the stationary core. A method for molding a foamed resin molded product, characterized by being narrowed at the peripheral edge of the surface. A method for molding a foamed resin molded article according to any one of claims 1 to 3,
The method for molding a foamed resin molded product, wherein the foamable resin in a molten state contains a physical foaming agent. A method for molding a foamed resin molded product according to claim 4,
The method for molding a foamed resin molded product, wherein the physical foaming agent is a fluid in a supercritical state. An apparatus for molding a foamed resin molded product by filling a part of the mold in a direction in which the volume of the cavity expands after filling the meltable foamable resin into the cavity of the mold,
A movable core that can be core-backed to form a porous resin part in which foam has grown in a foamed resin molded product, and an immobilization to form a foam-inhibited resin part in which foam growth is suppressed in the foamed resin molded product. A mold including a core;
Filling means for filling the molten moldable resin in the mold cavity;
A core back means for core-backing the movable core in a direction in which the volume of the cavity expands after the filling by the filling means;
When the core is backed by the core back means, an interval adjusting means for narrowing the gap between the cavity forming surface of the stationary core and the cavity forming surface facing the cavity forming surface at the peripheral edge of the cavity forming surface of the stationary core. An apparatus for molding a foamed resin molded product, comprising: It is a shaping | molding apparatus of the foamed resin molded product of Claim 6, Comprising:
The said space | interval adjustment means narrows the space | interval between the said cavity formation surfaces intermittently in the peripheral part of the cavity formation surface of a stationary core, The molding apparatus of the foamed resin molded product characterized by the above-mentioned. A molding apparatus for a foamed resin molded product according to claim 6 or 7,
The gap adjusting means includes a projecting portion in which a peripheral portion of the cavity forming surface of the stationary core projects a predetermined amount toward the opposing cavity forming surface and / or a cavity forming surface facing the cavity forming surface of the stationary core. A molding apparatus for a foamed resin molded product, wherein a portion corresponding to the peripheral edge portion of the cavity forming surface of the stationary core is constituted by a protruding portion projecting a predetermined amount toward the cavity forming surface of the stationary core. A molding apparatus for a foamed resin molded product according to any one of claims 6 to 8,
An apparatus for molding a foamed resin molded product, comprising physical foaming agent supply means for supplying a physical foaming agent to the molten foamable resin before filling by the filling means. A molding apparatus for a foamed resin molded product according to claim 9,
The said physical foaming agent supply means supplies the fluid of a supercritical state as a physical foaming agent, The molding apparatus of the foamed resin molded product characterized by the above-mentioned.

Images