JP2008087245A - Method and apparatus for molding resin molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for molding a resin molding which can surely apply counter pressure to a foamable resin to suppress the expansion of foamed cells. <P>SOLUTION: In molding of the resin molding, the foamable resin 47 in which a foaming agent is added into a second resin 41 is injected into a hollow molding formed by blow-molding a parison made of a first resin and foamed. The parison partitioned into a plurality of empty portions 23 and 24 is hung into opened molds 10a and 10b and, after the molds being closed, blow-molded by supplying pressurized gas into the empty portions, respectively. After the hollow molding having the empty portions is molded, while prescribed internal pressure is applied to the first empty portion 23 out of a plurality of the empty portions, the foamable resin is injected into the second empty portion 24 adjacent to the first empty portion and foamed against the internal pressure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  Conventionally, as a method for molding a resin molded product, after a parison made of a molten resin is suspended between a pair of molds that can be opened and closed, a parison is sandwiched between the molds and a gas such as air is blown into the mold. Generally known are hollow molding (so-called blow molding) and foam molding in which a foaming agent is contained in a resin and a resin containing the foaming agent is injected into a mold and foam molding is performed.

In recent years, a method for molding a resin molded product in which blow molding and foam molding are combined is known. For example, in Patent Document 1, a foamed thermoplastic resin piece is filled in a hollow molded body formed by blow molding a parison having a thermoplastic resin foam layer, and the foam piece is heated to fill the foam piece. A skin-molded foam-molded article obtained by fusing each other and a method for producing the same are disclosed.
JP 2004-284149 A

  By the way, in the molding of a resin molded product made of a foamable resin containing a foaming agent in the resin, if the foamable resin is injected into the mold, the foamed cells are enlarged at the start of injection, and at the start of injection and the injection. The foaming pressure of the foamable resin differs at the end, and may cause problems such as poor foaming and poor appearance. In particular, when the capacity of the resin molded product is large, such a problem appears more remarkably.

  On the other hand, when injecting the foamable resin into the mold, a gas such as air is supplied into the mold to maintain the inside of the mold at a predetermined pressure, and foaming is performed by applying a counter pressure to the foamable resin. There is known a molding method (so-called counter pressure method) in which foaming of the functional resin is suppressed, but the gas supplied into the mold is not leaked so that the inside of the mold is maintained at a predetermined pressure. Sealing the mold can be difficult.

  Therefore, the present invention has been made in view of the technical problem, and when foaming a foamable resin, a counter pressure can be reliably applied to the foamable resin, and the foam cell is enlarged. An object of the present invention is to provide a molding method and a molding apparatus for a resin molded product capable of suppressing the above.

  For this reason, in the molding method of the resin molded product according to claim 1 of the present application, the foaming in which the foaming agent is contained in the second resin inside the hollow molded body formed by blow molding the parison made of the first resin. A method of molding a resin molded product in which a foamable resin is injected and foamed, the step of hanging down the parison in which the interior of the parison is partitioned into a plurality of spaces in a mold that is opened A step of closing the mold after the parison is suspended in the mold, and blow molding the parison after the mold is closed, and a hollow mold having the plurality of spaces. Forming a body, and adjacent to the first space portion of the plurality of space portions in a state where a predetermined internal pressure is applied to the first space portion among the plurality of space portions of the hollow formed body. In the second space And a step of foam-molding the foamable resin injected into the second space against the internal pressure applied to the first space. It is characterized by that.

  Moreover, the invention method according to claim 2 of the present application is the invention method according to claim 1, wherein the magnitude of the internal pressure applied to the first space portion is injected into the second space portion. In synchronization with the injection timing of the foamable resin, it is controlled according to the time from the start of the injection of the foamable resin.

  Furthermore, the invention method according to claim 3 of the present application is characterized in that, in the invention method according to claim 1 or 2, the foamable resin contains reinforcing fibers for reinforcing the foamable resin. It is.

  Still further, the invention method according to claim 4 of the present application is the invention method according to any one of claims 1 to 3, wherein the first resin forming the outer surface of the resin molded product is a solid resin. It is characterized by.

  Furthermore, the invention method according to claim 5 of the present application is characterized in that in the invention method according to any one of claims 1 to 4, the foamable resin contains a physical foaming agent. is there.

  Furthermore, the invention method according to claim 6 of the present application is characterized in that, in the invention method according to claim 5, the physical foaming agent is a fluid in a supercritical state.

  Furthermore, the apparatus for molding a resin molded product according to claim 7 of the present application includes a foaming agent in the second resin in a hollow molded body formed by blow molding a parison made of the first resin. An apparatus for molding a resin molded product for injecting a foamed resin into a molded resin molded product, wherein the inside of the parison is placed in a mold that can be opened and closed and the mold that is opened and closed. An extrusion head for extruding the parison partitioned into a plurality of spaces and a mold closing the mold sandwiched by the parison extruded into the mold, and then adding to each of the spaces of the parison A pressurized fluid supply means for supplying a pressurized fluid to form a hollow molded body having the plurality of spaces, and a predetermined internal pressure is applied to a first space of the plurality of spaces of the hollow molded body. The pressure in the first space Pressure control means for controlling, and injection means for injecting the foamable resin into a second space portion adjacent to the first space portion among the plurality of space portions of the hollow molded body, The pressure control means is configured to foam-mold the foamable resin injected into the second space by the injection means against the internal pressure applied to the first space. It is characterized by controlling the pressure in the space.

  Still further, the invention according to claim 8 of the present application is the invention according to claim 7, wherein the pressure control means determines the magnitude of the internal pressure applied to the first space portion in the second space portion. In synchronism with the injection timing of the foamable resin injected into the liquid crystal, control is performed according to the time from the start of injection of the foamable resin.

  Still further, the invention according to claim 9 of the present application is the invention according to claim 7 or 8, wherein the injecting means contains the foamable resin containing the physical foaming agent in the second resin. It is characterized by being injected into the space.

  Furthermore, the invention according to claim 10 of the present application is the foamable resin according to the invention according to claim 9, wherein the injection means contains a fluid in a supercritical state as the physical foaming agent in the second resin. Is injected into the second space.

  According to the method for molding a resin molded product according to claim 1 of the present application, the second space into which the foamable resin is injected and the first space adjacent to the second space are formed by the first resin. Since it is sealed, when foaming the foamable resin, it is possible to reliably apply a counter pressure to the foamable resin, and to prevent the foamed cells of the foamable resin from being enlarged.

  Moreover, according to the invention method of claim 2 of the present application, since the counter pressure applied to the foamable resin can be adjusted, the foaming of the foamable resin can be adjusted, and the foamable resin expands excessively. Alternatively, the contraction can be prevented, and the above-described effects can be obtained with certainty.

  Furthermore, according to the method of the present invention according to claim 3 of the present application, even when reinforcing fibers are contained in the foamable resin, and foaming of the foamable resin is promoted by the springback phenomenon of the fibers, the counterpressure is applied to the foamable resin. Can be reliably applied, and the above-described effects can be effectively achieved. In a resin molded product molded from a foamable resin containing reinforcing fibers, the above-mentioned effects can be more effectively achieved without exposing the reinforcing fibers to the surface of the resin molded product and deteriorating the surface appearance. .

  Furthermore, according to the invention method of claim 4 of the present application, since the first resin forming the outer surface of the resin molded product is a solid resin, the surface of the resin molded product has a poor appearance such as bubble breakage. A resin molded product having a good surface appearance can be obtained without causing this.

  Furthermore, according to the invention method of claim 5 of the present application, since the foaming resin contains a physical foaming agent, a resin molded product having a fine foam cell diameter can be molded. It is possible to improve the physical properties such as the strength of the product and reduce the weight and thickness of the resin molded product.

  Furthermore, according to the inventive method of claim 6 of the present application, since the physical foaming agent is a fluid in a supercritical state, a resin molded product having finer foam cells can be molded. An effect can be produced more effectively.

  Furthermore, according to the molding apparatus for a resin molded product according to claim 7 of the present application, the second space portion into which the foamable resin is injected and the first space portion adjacent to the second space portion are the first. When the foamable resin is subjected to foam molding, it is possible to reliably apply a counter pressure to the foamable resin, and to suppress the expansion of foamed cells of the foamable resin. .

  Furthermore, according to the invention according to claim 8 of the present application, since the counter pressure applied to the foamable resin can be adjusted, foaming of the foamable resin can be adjusted, and the foamable resin expands excessively. Alternatively, the contraction can be prevented, and the above-described effects can be obtained with certainty.

  Still further, according to the invention according to claim 9 of the present application, the injecting means injects a foamable resin containing a physical foaming agent into the second resin into the second space portion, thereby increasing the foam cell diameter. It is possible to mold a fine resin molded product, improve physical properties such as strength of the resin molded product, and reduce the weight and thickness of the resin molded product.

  Still further, according to the invention according to claim 10 of the present application, the injection means injects a foamable resin containing a fluid in a supercritical state as a physical foaming agent into the second resin into the second space. As a result, a resin molded product having even finer foam cells can be molded, and the above-described effects can be more effectively exhibited.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a cross-sectional explanatory view showing a molding die and an extrusion head of a molding apparatus for a resin molded product according to an embodiment of the present invention. As shown in FIG. 1, the molding apparatus 1 includes a pair of molding dies 10 a and 10 b provided to be openable and closable, and an extrusion head 30 that extrudes a parison 20 made of a first resin. Further, as will be described later, the molding apparatus 1 includes blow bins 13a and 13b as pressurized fluid supply means for supplying pressurized fluid into the molds 10a and 10b, and second molds in the molds 10a and 10b. And an injection device 40 as injection means for injecting a foamable resin 47 containing a foaming agent in the resin 41.

  The blow pins 13a and 13b supply pressurized fluid supplied from a pressurized fluid supply source (not shown) into the molds 10a and 10b. As shown in FIG. It is configured to control the pressure in a predetermined space that communicates with each of the blow pins 13a and 13b. In addition, the molds 10a and 10b are provided with insertion holes 12a and 12b for allowing the blow pins 13a and 13b to pass therethrough, respectively, and the blow pins 13a and 13b are configured to be able to advance and retract in the insertion holes 12a and 12b, respectively. ing.

  The injection apparatus 40 injects a foamable resin 47 containing a fluid in a supercritical state as a foaming agent into the molds 10a and 10b. As shown in FIG. Is provided with a cylinder 42 for kneading and melting. A screw 43 is provided inside the cylinder 42, and a screw drive mechanism and an injection mechanism (both not shown) are connected to the rear end of the screw 43.

  In the injection device 40, the second resin 41 put into the cylinder 42 is kneaded and melted by the screw 43. Then, for the second resin 41 kneaded and melted, the inert gas brought into a supercritical state via a supercritical fluid generator 45 from a cylinder 44 containing an inert gas such as carbon dioxide or nitrogen, Injected by a supercritical fluid injector 46. As a result, a foamable resin 47 containing the foaming agent in the second resin 41 is formed.

  The foamable resin 47 is injected into the molds 10a and 10b while the screw 43 is rotated by the screw driving mechanism and injected by the injection mechanism. The molding die 10b is provided with an injection path 14 that communicates with the nozzle 48 of the injection device 40 and injects the foamable resin 47 into the molding dies 10a and 10b. The injection device 40 includes a heater (not shown) around the cylinder 42, and is configured to sequentially heat and melt the second resin 41 put into the cylinder 42.

  Further, the molding apparatus 1 includes a control unit (not shown) that comprehensively controls the molding apparatus 1. The control unit includes an opening / closing drive of the molding dies 10 a and 10 b, a parison extrusion mechanism of the extrusion head 30, It controls the operation mechanism of the blow pins 13a and 13b, the injection mechanism of the blow pins 13a and 13b, and the like. The control unit is configured with a microcomputer as a main part, for example.

Next, molding of a resin molded product using the molding apparatus 1 for resin molded product configured as described above will be described.
First, in a state in which the molds 10a and 10b are opened, the melt is heated and melted from the extrusion head 30 into the molds 10a and 10b, specifically between the cavity surfaces 11a and 11b provided in the molds 10a and 10b, respectively. The parison 20 made of the first resin is suspended. As the first resin, for example, a non-foamed solid resin such as a thermoplastic resin can be used.

  FIG. 2 is a cross-sectional explanatory view taken along line Y2-Y2 in FIG. 1. As shown in this figure, the parison 20 is provided in a cylindrical peripheral wall portion 21 and in the peripheral wall portion 21. The peripheral wall portion 21 and the partition wall portion 22 are integrally formed by extrusion molding. Note that the inside of the parison 20 is open at the tip side pushed out from the extrusion head 30, and is partitioned into a first space portion 23 and a second space portion 24 by the partition wall portion 22.

  Next, the molds 10a and 10b are closed, and the upper and lower ends of the parison 20 are sandwiched between the molds 10a and 10b. As a result, the space inside the parison 20 is closed, and two hollow spaces, specifically the first space 23 and the second space 24, partitioned by the partition wall 22 inside the parison 20. Is formed. Then, the pressurized fluid is supplied to the first space portion 23 and the second space portion 24. As the pressurized fluid, for example, a pressurized gas such as compressed air can be used.

  FIG. 3 is an explanatory cross-sectional view showing a state where pressurized gas is supplied to the parison located in the mold. Both the blow pins 13a and 13b are advanced, pressurized gas is supplied to the first space portion 23 by the blow pins 13a, pressurized gas is supplied to the second space portion 24 by the blow pins 13b, and the parison 20 is blow-molded. The As a result, the inner space of the parison 20 expands, the peripheral wall 21 is pressed against the cavity surfaces 11a and 11b of the molds 10a and 10b, and a hollow molded body having a shape along the cavity surfaces 11a and 11b is formed. The

  The partition wall 22 that divides the space inside the parison 20 is moved to a predetermined position according to the pressure in the first space 23 and the pressure in the second space 24. As described above, the pressure control device 50 controls the pressure in the first space portion 23 and the pressure in the second space portion 24 so as to move and hold the partition wall portion 22 to a predetermined position. .

  FIG. 4 is a schematic explanatory view showing a state in which a foamable resin is injected into the mold. When the parison 20 located in the molds 10a and 10b is blow-molded, next, a fluid in a supercritical state is contained in the second space 24 as a foaming agent from the injection device 40 to the second resin 41. The expanded foamed resin 47 is injected. For example, a thermoplastic resin can be used as the second resin.

  When the foamable resin 47 is injected into the second space portion 24, the pressure in the second space portion 24 is controlled by the pressure control device 50 along with the injection of the foamable resin 47, and the second The gas in the space 24 is discharged through the blow pin 13b. On the other hand, the first space portion 23 is supplied with pressurized gas by the blow pin 13 a and is held at a predetermined pressure by the pressure control device 50. In this way, a predetermined internal pressure is applied to the first space portion 23.

  The internal pressure applied to the first space 23 is synchronized with the injection timing of the foamable resin 47 injected into the second space 24 according to the time from the start of injection of the foamable resin 47. The magnitude of the internal pressure is controlled. Specifically, when the foamable resin 47 is injected into the second space portion 24, the partition wall portion 22 that partitions the first space portion 23 and the second space portion 24 is prevented from moving. When the pressure in the first space portion 24 is controlled corresponding to the pressure in the second space portion 24 and the foamable resin 47 is filled in the second space portion 24, the second space portion 24. The pressure of the first space portion 23 is controlled so that the foaming pressure of the foamable resin injected into the inside is substantially constant. Note that foaming of the foamable resin 47 can be suppressed or promoted by controlling the pressure of the first space portion 23.

  FIG. 5 is an explanatory cross-sectional view showing a state in which a foamable resin is injected into the mold. When the foamable resin 47 is filled in the second space 24 in a state where a predetermined internal pressure is applied to the first space 23, the blow pin 13b is moved backward as shown in FIG. Then, the pressure of the first space portion 23 is controlled so that the foaming pressure of the foamable resin 47 is substantially constant, and the partition wall portion 22 is moved and the foamable resin 47 is foamed and expanded as indicated by an arrow X1. In addition, the gas in the 1st space part 23 is discharged | emitted through the blow pin 13a.

  As described above, in the molding apparatus 1, the foamable resin 47 injected into the second space portion 24 is foam-molded against the internal pressure applied to the first space portion 23, and the first space portion. The size of the internal pressure applied to 23 is controlled according to the time from the start of injection of the foamable resin 47 injected into the second space 24. The internal pressure applied to the first space portion 23 is controlled by controlling the pressure of the first space portion 23 with the pressure control device 50.

  FIG. 6 is a cross-sectional explanatory view showing a state where the foamable resin injected into the mold is foam-molded. As shown in this figure, in the molding apparatus 1, the movement of the partition wall 22 is stopped at a predetermined position. The pressure control device 50 controls the pressure of the first space portion 23 according to the pressure of the second space portion 24, specifically, the foaming pressure of the foamable resin 47 so as to stop the movement of the partition wall portion 22. .

  Then, the foamable resin 47 in a molten state is gradually cooled and solidified, and the foamable resin 47 is injected and foamed into the hollow molded body made of the first resin into which the parison 20 is blow-molded. A resin molded product 25 is molded. The resin molded product 25 includes a first space portion 23 and a second space portion 24 in which a foamable resin 47 is foam-molded.

  In the present embodiment, the partition wall portion 22 is moved to the peripheral wall portion 21 in the resin molded product 25 in which the foamable resin 47 is injected and foamed into the hollow molded body formed by blow molding the parison 20. In other words, the foamable resin 47 is foam-molded so that the first space portion 23 exists, but the partition wall portion 22 may be moved to the peripheral wall portion 21.

  FIG. 7 is a cross-sectional explanatory view showing a modified example of a resin molded product molded using the molding apparatus. As shown in this figure, when the movement of the partition wall 22 is stopped at a predetermined position and the pressure in the first space 23 is controlled and moved to the peripheral wall 22, the partition 22, the peripheral wall 21, Is welded. Then, the foamable resin 47 in a molten state may be gradually cooled and solidified to obtain a resin molded product 26 having the partition wall portion 22 and the peripheral wall portion 21 on the surface of the foamable resin 47. The blow pin 13a is retracted when the gas in the first space 23 is discharged.

Next, an injection mechanism of the foamable resin 47 from the injection device 40 to the first space 24 will be described with reference to FIGS.
8 to 10 sequentially show the steps in which the foamable resin 47 is injected from the injection device 40 into the first space portion 24, and shows the portion B in FIG. FIG. 8 is an explanatory view showing a state in which the first valve body and the second valve body provided in the injection path are closed, and FIG. 9 is a diagram illustrating the opening of the first valve body provided in the injection path. FIG. 10 is an explanatory view showing a state where the second valve body is closed, and FIG. 10 is an explanatory view showing a state where the first valve body and the second valve body provided in the injection path are opened.

  As shown in FIG. 8, the injection path 14 communicates with a recess 15 formed in the cavity surface 11 b of the molding die 10 b, and a first valve body 51 is provided on the bottom side of the recess 15. The first valve body 51 is connected to the drive cylinder 52 via the rod 53, and is configured to be movable in the vertical direction by the operation of the drive cylinder 52. The first valve body 51 moves upward. The injection path 14 is closed. Further, the injection path 14 is provided with a second valve element 54 configured to open and close the injection path 14 and be movable in the horizontal direction. Thereby, in the state which the 1st valve body 51 and the 2nd valve body 54 opened, the foamable resin 47 can be inject | poured in the shaping | molding die 10a, 10b.

  As shown in FIG. 8, with the first valve body 51 and the second valve body 54 closing the injection path 14, pressurized gas is supplied to the second space portion 24 of the parison 20, and the peripheral wall portion. When 21 is pressed against the cavity surface 11b, the peripheral wall 21 of the parison 20 is also pressed against the surface of the recess 15 in a U-shaped cross section, but the thickness of the peripheral wall 21 is formed thin.

  Then, as shown in FIG. 9, when the pressure of the second space portion 24 is increased after operating the drive cylinder 52 to move the first valve body 51 downward, the U-shaped cross section is formed in the recess 15. The peripheral wall portion 21 formed in the shape is opened at the bottom portion 21a. When the pressure in the second space is increased, the pressure in the second space 24 is controlled so that the partition wall 21 is held at a predetermined position.

  Next, after the second valve body 54 is moved to open the injection path 14 and the second space 24 and the injection path 14 are communicated with each other, as shown in FIG. Injected into the second space 24 from the injection device 40. 8 to 10 show an example of injecting the foamable resin into the hollow molded body in which the parison 20 is blow-molded. The foamable resin 47 is injected by other suitable means. You may make it do.

  In the molding apparatus 1 according to the present embodiment, when the foamable resin 47 is injected into the second space 24, the gas in the second space 24 is discharged through the blow pin 13a. You may make it provide the gas discharge hole which discharges | emits the gas in the 2nd space part 24 in the surrounding wall part 21 which prescribes | regulates the 2 space part 24. FIG.

  FIG. 11 is a cross-sectional explanatory view showing a state in which pressurized gas is supplied to a parison located in a mold of the molding apparatus in a molding apparatus for a resin molded product according to another embodiment of the present invention. 12 is a schematic explanatory view showing a state in which a foamable resin is injected into a mold of the molding apparatus. In these drawings, components having the same configuration as the molding apparatus 1 described above and having the same functions are denoted by the same reference numerals, and further description thereof is omitted.

  In a molding apparatus 60 for a resin molded product according to another embodiment of the present invention, as shown in FIG. 11, in a state where the molds 10a and 10b are closed, the space formed by the cavity surfaces 11a and 11b is within the space. A pin 62 is provided on the mold 10b so as to protrude. The pin 62 is tapered at the front end side and attached to the movable plate 61 at the rear end side. The movable plate 61 is configured to be movable back and forth with respect to the space formed by the cavity surfaces 11a and 11b by, for example, a drive cylinder.

  Further, in the molding apparatus 60, an exhaust path 64 for discharging gas in the space formed by the cavity surfaces 11a and 11b is formed in the molding die 10b, and the exhaust path 64 advances the movable plate 61 forward. The movable plate 61 is closed by moving the movable plate 61 backward.

  As described above, when pressurized gas is supplied to the second space portion 24 of the parison 20 and the peripheral wall portion 21 is pressed against the cavity surface 11b, as shown in FIG. The peripheral wall 21 is pressed against the cavity surface 11 b with the pin 61 pierced, and a gas discharge hole 21 b is formed in the peripheral wall 21 by the pin 61.

  Then, when the foamable resin 47 is injected into the second space 24, the blow pin 13b is retracted and the movable plate 61 is retracted as shown in FIG. Thereby, with the injection of the foamable resin 47, the gas in the second space 24 can be discharged from the gas discharge hole 21b through the exhaust path 64.

  In the present embodiment, as shown in FIG. 2, the parison 20 having the peripheral wall portion 21 and the partition wall portion 22 is used, but other shapes of parison can also be used. FIG. 13 is a cross-sectional explanatory view showing a modified example of the parison used in the resin molded product molding apparatus according to the embodiment of the present invention. FIG. 13A is a sectional view showing the first modified example of the parison. FIG. 13B is a cross-sectional explanatory view showing a second modified example of the parison.

  As shown in FIG. 13A, a parison 80 having a double tube structure can be used. The parison 80 includes an outer cylindrical portion 81 that is formed in a substantially cylindrical shape, and an inner cylindrical portion 82 that is positioned inside the outer cylindrical portion 81 and is formed in a substantially cylindrical shape, and a space inside the outer cylindrical portion 81. Is partitioned by an inner cylindrical portion 82, a first space portion 83 is provided inside the inner cylindrical portion 82, and a second space portion 84 is provided between the outer cylindrical portion 81 and the inner cylindrical portion 82. ing.

  When the parison 80 is used, a foamable resin is injected into the second space portion 84 and the pressure of the first space portion 83 is controlled to resist the internal pressure of the first space portion 83. The foamable resin injected into the second space portion 84 can be foamed toward the first space portion 83 side. The foamable resin is injected into the first space 83 and the pressure of the second space 84 is controlled to inject the first space 83 against the internal pressure of the second space 84. The foamed resin thus formed may be foamed toward the second space 84 side.

  Further, as shown in FIG. 13B, it is also possible to use a parison 90 formed in a substantially 8-character shape. The parison 90 includes a first cylindrical portion 91 and a second cylindrical portion 92 formed in a substantially cylindrical shape, and the first cylindrical portion 91 and the second cylindrical portion 92 are integrally extruded. . In the parison 90, a first space portion 93 is provided inside the first cylindrical portion 91, and a second space portion 94 is provided inside the second cylindrical portion 92.

  When the parison 90 is used, a foamable resin is injected into the first space portion 93 and the pressure in the second space portion 94 is controlled to resist the internal pressure of the second space portion 94. The foamable resin injected into the one space portion 93 can be foamed. Alternatively, a foamable resin is injected into the second space portion 94, and the pressure of the first space portion 93 is controlled to resist the internal pressure of the first space portion 93 and injected into the second space portion 94. You may make it foam the made foamable resin.

  In the present embodiment, a pressurized gas such as compressed air is used as the pressurized fluid, but an incompressible fluid can also be used. When using an incompressible fluid, it is preferable to use it by heating. In this embodiment, a fluid in a supercritical state is used as the foaming agent, but other physical foaming materials or chemical foaming agents can also be used.

  As is apparent from the above description, in the present embodiment, when molding the resin molded product, the second space portion into which the foamable resin is injected and the first space adjacent to the second space portion. Since the part is sealed with the first resin, when foaming the foamable resin, it is possible to reliably apply a counter pressure to the foamable resin and to prevent the foamed resin foam cells from becoming enlarged. can do.

  The magnitude of the internal pressure applied to the first space 23 depends on the time from the start of the foaming resin injection in synchronization with the injection timing of the foamable resin injected into the second space. Since the counter pressure applied to the foamable resin can be adjusted, the foaming of the foamable resin can be controlled, and the foamable resin is prevented from excessively expanding or contracting. Therefore, the above-described effects can be obtained with certainty.

  Furthermore, since the first resin forming the outer surface of the resin molded product is a solid resin, a resin molded product having a good surface appearance is obtained without causing appearance defects such as bubble breakage on the surface of the resin molded product. be able to.

  Furthermore, since the foaming resin contains a physical foaming agent, it is possible to mold a resin molded product with a fine foam cell diameter, and improve the physical properties such as strength of the resin molded product. Can be reduced in weight and thickness.

  Furthermore, since the physical foaming agent is a fluid in a supercritical state, a resin molded product having finer foamed cells can be molded, and the above-described effects can be more effectively achieved.

  In the present embodiment, the foamable resin 47 is injected into the first space 24 by the injection device 40. However, the foamable resin 47 may further contain reinforcing fibers that reinforce the foamable resin. May be. As described above, even when the reinforcing resin is contained in the expandable resin and the foaming of the expandable resin is promoted by the springback phenomenon of the fiber, according to the molding method of the resin molded product as described above, the expandable resin The counter pressure can be reliably applied to the foamed resin, and the expansion of the foam cell of the foamable resin can be suppressed. In a resin molded product molded from a foamable resin containing reinforcing fibers, the reinforcing fibers are not exposed on the surface of the resin molded product and the surface appearance is not deteriorated. it can.

  In the present embodiment, two space portions are formed inside the parison, but a plurality of space portions such as three space portions may be formed inside the parison. In such a case, the same effect as that of the above embodiment can be obtained by controlling the pressure in the space adjacent to one space into which the foamable resin is injected.

  As described above, the present invention is not limited to the illustrated embodiments, and it goes without saying that various improvements and design changes can be made without departing from the gist of the present invention.

  The present invention relates to a molding method and a molding apparatus for a resin molded product capable of reliably applying a counter pressure to a foamable resin when the foamable resin is injected into a hollow molded body formed by blow molding a parison and foamed. For example, the present invention can be applied to molding of a resin molded product such as a trunk board that is assembled to a vehicle body.

It is sectional explanatory drawing which shows the shaping | molding die and extrusion head of the shaping | molding apparatus of the resin molded product which concerns on embodiment of this invention. FIG. 2 is a cross-sectional explanatory view taken along line Y2-Y2 in FIG. It is sectional explanatory drawing which shows the state by which pressurized gas was supplied to the parison located in the said shaping | molding die. It is a schematic explanatory drawing which shows the state by which foamable resin is inject | poured in the said shaping | molding die. It is sectional explanatory drawing which shows the state by which foamable resin was inject | poured in the said shaping | molding die. It is sectional explanatory drawing which shows the state by which foaming resin inject | poured in the said shaping | molding die was foam-molded. It is sectional explanatory drawing which shows the modification of the resin molded product shape | molded using the said shaping | molding apparatus. It is explanatory drawing which shows the state which the 1st valve body and 2nd valve body which were provided in the said injection | pouring path | route closed. It is explanatory drawing which shows the state which the said 1st valve body provided in the said injection | pouring path | route opened and the said 2nd valve body closed. It is explanatory drawing which shows the state which the said 1st valve body and said 2nd valve body provided in the said injection | pouring path | route opened. In the molding apparatus of the resin molded product which concerns on another embodiment of this invention, it is cross-sectional explanatory drawing which shows the state by which pressurized gas was supplied to the parison located in the shaping | molding die of this molding apparatus. It is a schematic explanatory drawing which shows the state by which foamable resin is inject | poured in the shaping | molding die of the said shaping | molding apparatus. It is sectional explanatory drawing which shows the modification of the parison used for the shaping | molding apparatus of the resin molded product which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 60 Molding apparatus 10a, 10b Mold 13a, 13b Blow pin 20, 80, 90 Parison 23, 83, 93 1st space part 24, 84, 94 2nd space part 30 Extrusion head 40 Injection apparatus 41 2nd resin 47 Expandable resin

Claims (10)

A molding method of a resin molded product in which a foamable resin containing a foaming agent in a second resin is injected into a hollow molded body formed by blow-molding a parison made of a first resin and foamed. And
A step of hanging the parison in which the inside of the parison is partitioned into a plurality of spaces in a mold that is opened; and
Closing the mold after the parison is suspended in the mold; and
After the mold is closed, blow molding the parison and molding the hollow molded body having the plurality of spaces; and
In a state in which a predetermined internal pressure is applied to the first space portion among the plurality of space portions of the hollow molded body, the second space portion adjacent to the first space portion among the plurality of space portions is in the second space portion. Injecting a foamable resin;
Foaming the foamable resin injected into the second space against the internal pressure applied to the first space;
A method for molding a resin molded product, comprising:   The magnitude of the internal pressure applied to the first space portion is a time from the start of the injection of the foamable resin in synchronization with the injection timing of the foamable resin injected into the second space portion. The method for molding a resin molded product according to claim 1, wherein the method is controlled according to the method.   The method for molding a resin molded product according to claim 1, wherein the foamable resin contains reinforcing fibers that reinforce the foamable resin.   The method for molding a resin molded product according to any one of claims 1 to 3, wherein the first resin forming the outer surface of the resin molded product is a solid resin.   The method for molding a resin molded product according to any one of claims 1 to 4, wherein the foamable resin contains a physical foaming agent.   The method for molding a resin molded product according to claim 5, wherein the physical foaming agent is a fluid in a supercritical state. A foamed resin in which a foaming agent is added to the second resin is injected into a hollow molded body formed by blow molding a parison made of the first resin, and a resin molded product is molded by foam molding. A molding apparatus for resin molded products,
A mold that can be opened and closed;
An extrusion head for extruding the parison in which the interior of the parison is partitioned into a plurality of spaces in the mold that has been opened;
After the mold is closed with the parison extruded into the mold, a pressurized fluid is supplied to each of the plurality of spaces of the parison, and the hollow molded body having the plurality of spaces. Pressurized fluid supply means for forming
Pressure control means for controlling the pressure of the first space portion so as to apply a predetermined internal pressure to the first space portion among the plurality of space portions of the hollow molded body;
Injecting means for injecting the foamable resin into a second space portion adjacent to the first space portion among the plurality of space portions of the hollow molded body,
With
The pressure control means is configured to foam-mold the foamable resin injected into the second space by the injection means against the internal pressure applied to the first space. Control the pressure in the space of the
An apparatus for molding a resin molded product.   The pressure control means synchronizes the magnitude of the internal pressure applied to the first space portion in synchronism with the injection timing of the foamable resin injected into the second space portion. 8. The apparatus for molding a resin molded product according to claim 7, wherein the molding is controlled according to a time from the start of injection.   The said injection | pouring means inject | pours the said foamable resin which made the said 2nd resin contain the physical foaming agent in the said 2nd space part, The shaping | molding of the resin molded product of Claim 7 or 8 characterized by the above-mentioned. apparatus.   The said injection | pouring means inject | pours the said foamable resin which made the said 2nd resin contain the fluid of the supercritical state as the said physical foaming agent in the said 2nd space part. Molding equipment for resin molded products.

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