JP2008284734A - Molding method and molding apparatus for resin molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin molded product excellent in appearance, lightweight nature, rigidity through enhancing an extent of foaming of an inside foamed resin that is covered by a surface layer made of a solid resin and through avoiding the partial drop of the rigidity of the surface layer that constitutes the primary hollow molded body. <P>SOLUTION: The molding method of the resin molded products comprises a process of molding a parison with a solid resin, a process of sandwiching the molded parison with molding dies and blowing the air into the inside to form into a predetermined shape, a process wherein, while the obtained hollow molded body is kept in the molding dies, a molten foaming resin is injected into the hollow molded body, a process wherein, while the molding dies are opened by a predetermined amount after the injection, the foaming resin is foamed to be filled into the hollow molded body and a process of forming, on the surface of the part X where the hollow molded body is stretched by the opening of the molding dies by the predetermined amount in the above process, the recess Y that retracts to the inside side of the resultant resin molded product A. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

Conventionally, resin molded products are sometimes used for automobile parts. Especially, from the viewpoint of appearance, lightness and rigidity, resin molded products whose interior is made of foamed resin and whose surface layer is made of solid resin (non-foamed resin) are used. For example, it may be used for an interior / exterior member of an automobile. In this regard, Patent Document 1 discloses that a hollow molded body having a foam layer is filled with a thermoplastic resin foam piece, and the foam piece is heated with a heating medium such as steam to mutually connect the foam pieces. It is disclosed that a foamed article with a skin is obtained by fusing to the surface.
JP2004-284149 (paragraph 0025)

  However, since the technique obtains a foamed molded article covered with the skin of a hollow molded article by heat-sealing the already foamed resin pieces, bubbles are crushed and foamed at the time of heat-sealing. As a result, there is a problem that a sufficiently satisfactory product cannot be obtained in terms of lightness and rigidity. In addition, since the surface layer portion has a foam layer, there is a problem that bubbles appear in the surface layer portion, and a sufficiently satisfactory appearance cannot be obtained.

  On the other hand, in order to ensure good moldability of the primary hollow molded body and to ensure good appearance and rigidity of the final molded product, the primary hollow molded body is molded by blow molding, and this primary hollow molded body is formed. It is conceivable that a foamable resin is injected into the molded body and a predetermined amount of the mold is opened (core back) at the time of foaming. However, in that case, there arises a problem that the primary hollow molded body is partially stretched by the core back of the mold, and the stretched portion is thinned to reduce the rigidity.

  The present invention sufficiently enhances the degree of foaming of the foam resin inside covered with the surface layer portion made of solid resin, and avoids the partial rigidity reduction of the surface layer portion composed of the primary hollow molded body, It is an object to provide a resin molded product having excellent properties, lightness, and rigidity.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a method for molding a resin molded product in which the inside is made of a foamed resin and the surface layer portion is made of a solid resin, and a parison molding step of molding a parison with the solid resin. And a molding process in which a molded parison is sandwiched between molding molds and a gas is blown into the interior to form into a predetermined shape, and a foamed resin in a molten state with the resulting hollow molded body left in the molding mold In the hollow molded body, and after the injection, the foaming resin is foamed while opening the molding die by a predetermined amount, and the resin is filled in the hollow molded body. A recessed portion forming step of forming a recessed portion that immerses inside the obtained resin molded product on the surface of the portion where the hollow molded body is extended by opening a predetermined amount of the mold.

  Next, the invention according to claim 2 of the present application is the method for molding a resin molded product according to claim 1, wherein the formation of the recess in the recess forming step is performed by molding the obtained resin molded product. It is characterized by carrying out by projecting the projecting mold from the mold toward the resin molded product while remaining in the mold.

  Next, the invention according to claim 3 of the present application is the method for molding a resin molded product according to claim 2, wherein one of the molds is the other outer peripheral mating surface of the mold when the mold is clamped. An outer peripheral mold that comes into contact with the outer peripheral mold, and an inner mold that is movable relative to the outer peripheral mold in a direction close to the other of the molding dies or in a direction away from the other of the molding dies, and the shaping step And in the injection step, the mold is clamped in a state in which the internal mold is moved in a direction close to the other of the molds, and in the filling step, the mold is clamped in the state, A protruding mold provided in the outer peripheral mold in a state where the inner mold is moved in a direction away from the other of the molding dies, and in the recess forming step, the inner mold is moved in a direction away from the other of the molding dies. And projecting into the mold That.

  Next, the invention according to claim 4 of the present application is the method for molding a resin molded product according to any one of claims 1 to 3, wherein in the injection step, a foamable resin containing reinforcing fibers is used. It is characterized by injecting.

  Next, the invention according to claim 5 of the present application is the method for molding a resin molded product according to any one of claims 1 to 4, wherein, in the injection step, a foamable resin containing a physical foaming agent. It is characterized by injecting.

  Next, the invention according to claim 6 of the present application is the method for molding a resin molded article according to claim 5, wherein, in the injection step, foaming containing a fluid in a supercritical state as the physical foaming agent. It is characterized by injecting a functional resin.

  On the other hand, the invention according to claim 7 of the present application is a molding apparatus for a resin molded product in which the inside is made of foamed resin and the surface layer portion is made of solid resin, and the parison molding means for molding the parison with the solid resin, A molding die sandwiched between the parisons molded by the parison molding means, a shaping means for blowing a gas into the inside of the parison sandwiched between the molding dies and shaping into a predetermined shape, and the shaping means obtained An injection means for injecting a molten foamable resin into the hollow molded body in the mold, and after the injection of the foamable resin by the injection means, the foamable resin is foamed while opening the mold by a predetermined amount. Filling means for filling the hollow molded body with the resin, and filling the foamable resin by the filling means, the surface of the portion where the hollow molded body is stretched by opening a predetermined amount of the mold, Gain Characterized in that it comprises a recess forming means for forming a recess retracted into the inner side of the resin molded article.

  Next, the invention according to claim 8 of the present application is the apparatus for molding a resin molded product according to claim 7, wherein the recess forming means is a protrusion that can freely protrude from the mold into the mold. It has a type | mold, A recessed part is formed by making this protrusion type | mold project toward the resin molded product remaining in the shaping | molding die, It is characterized by the above-mentioned.

  Next, the invention according to claim 9 of the present application is the apparatus for molding a resin molded product according to claim 8, wherein one of the molds is the other outer peripheral mating surface of the mold during clamping. An outer peripheral mold that is in contact with the outer peripheral mold, and an inner mold that is movable relative to the outer peripheral mold in a direction close to the other of the molding dies or in a direction away from the other of the molding dies, At the time of shaping by the shaping means and at the time of injection by the injection means, the inner mold is moved in a direction close to the other of the molding dies, so that the mold is clamped. At the time of filling, the inner mold moves away from the other of the molds in the clamped state, and the mold is moved from the other of the molds when the recess is formed by the recess forming means. Moved away In, wherein the outer peripheral type are provided a protruding type is projected toward the inside of the mold.

  Next, the invention according to claim 10 of the present application is the molding apparatus for a resin molded product according to any one of claims 7 to 9, wherein the injection means is a foamable resin containing a physical foaming agent. It is characterized by injecting.

  Next, an invention described in claim 11 of the present application is the apparatus for molding a resin molded product according to claim 10, wherein the injection means is a foam containing a supercritical fluid as the physical foaming agent. It is characterized by injecting a functional resin.

  First, according to the invention described in claim 1 or claim 7, in order to ensure good moldability of the primary hollow molded body and to ensure good appearance and rigidity of the final molded product, a solid resin is used. Injecting a foamed resin in a molten state into a hollow molded body in a state where a hollow molded body obtained by sandwiching a molded parison between molding molds and blowing a gas into the inside to be shaped into a predetermined shape is left in the molding mold, Thereafter, the foamable resin is foamed while the mold is opened by a predetermined amount, and the resin is filled into the hollow molded body. Therefore, foaming of the foamed resin is sufficiently promoted, and lightness and rigidity are improved. Furthermore, since the surface layer portion is made of a solid resin (non-foamed resin), bubbles do not appear in the surface layer portion, and the appearance can be improved.

  Moreover, in the obtained resin molded product, on the surface of the portion (the stretched portion of the hollow molded body, the thinned portion) where the hollow molded body has been stretched and thinned by opening the molding die by a predetermined amount (core back). In addition, since the concave portion that immerses inside the resin molded product is formed, even if the surface layer portion constituted by the hollow molded body is partially stretched and thinned, the stretched portion and the rigidity of the thinned portion Can be easily and effectively prevented as compared with the case where such a recess is not formed. Therefore, resin molding with excellent appearance, light weight, and rigidity by sufficiently increasing the degree of foaming of the internal foamed resin covered with the surface layer made of solid resin and avoiding partial deterioration of the rigidity of the surface layer. The product can be obtained easily and reliably.

  In that case, according to invention of Claim 2 or Claim 8, in the state which formed the recessed part with respect to the surface of the to-be-stretched part of the said hollow molded object, the obtained resin molded product was left in the shaping | molding die. Since the projecting mold is protruded from the mold toward the resin molded product, the recess can be continuously formed before the mold is opened to take out the resin molded product from the mold. Improvement is achieved. In addition, during the period when the stretched part (thinned part) of the surface layer part composed of the hollow molded body still retains flexibility at a high temperature before the resin molded product cools down, Therefore, the problem that the surface layer portion is broken by the protruding mold and the foamed resin inside can be seen is avoided.

  Next, according to the invention of claim 3 or claim 9, one of the molding dies is an outer peripheral die that comes into contact with the other outer peripheral mating surface of the molding die at the time of clamping, and the molding die with respect to the outer peripheral die. An inner mold that is relatively movable in a direction close to the other of the molds or a direction away from the other of the molds, and when the parison is molded and the foamable resin is injected, the inner mold is The mold is clamped in a state of being moved in the direction close to the other, and when foaming resin is filled and filled, the inner mold is moved away from the other of the molds while the mold is clamped As a result, it is possible to open the mold by a predetermined amount (core back) with a simple configuration without complicating the structure of the mold and its driving mechanism.

  Moreover, at the time of forming the recess, the projecting mold provided in the outer peripheral mold is projected toward the molding mold in a state where the inner mold is moved away from the other of the molding mold. Aiming at the appropriate part (stretched part of the hollow molded body, thinned part), the concave part can be reliably molded using the protruding mold, and the partial rigidity reduction of the surface layer part can be avoided more reliably. Is possible.

  Next, according to the fourth aspect of the present invention, when the foamable resin is injected, the foamable resin containing the reinforcing fiber is injected. By the back phenomenon, it becomes possible to further promote the foaming of the foamed resin.

  Next, according to the invention described in claim 5 or claim 10, since the foaming resin containing the physical foaming agent is injected at the time of the injection of the foamable resin, due to the effect of the physical foaming agent, The foamed cell diameter inside the molded product can be made small, and the rigidity of the resin molded product can be further improved.

  Next, according to the invention described in claim 6 or claim 11, when the foamable resin is injected, the foamable resin containing the fluid in the supercritical state is injected. With this function, the foamed cell diameter inside the molded product can be made to be a finer diameter, and the rigidity of the resin molded product can be further improved. Hereinafter, the present invention will be described in more detail through the best mode for carrying out the invention.

  FIG. 1 is a longitudinal sectional view showing the configuration of a parison P extrusion molding apparatus (parison molding means) 1 according to this embodiment, and FIG. 2 is a sectional view taken along the line II-II in FIG. The accumulator head 2 of the device 1 has a cylinder 3, a ring piston 4 and a core 5. A resin storage chamber 6 is formed below the ring piston 4. The resin storage chamber 6 is connected to an extruder 8 of a solid resin N (see FIG. 5) that is a raw material of the parison P via an upper annular communication path 7.

  A die 9 is provided at the lower end of the cylinder 3. A core support 10 is provided at the lower end of the core 5. A core 11 is fitted to the core support 10 so as to be movable up and down. An annular die slit 12 is formed between the die 9 and the core 11. The die slit 12 communicates with the resin storage chamber 6. The parison P is extruded from the die slit 12 in a tube shape and hangs down.

  The core 11 is moved up and down by a core driving hydraulic cylinder 14 via a core driving rod 13. Thereby, the space | interval of the die slit 12, ie, the thickness of the parison P extruded from the die slit 12 and drooping, can be adjusted.

  The ring piston 4 is moved up and down by a ring piston driving hydraulic cylinder 16 via a ring piston driving rod 15. Thereby, the accumulator which pumps the resin in the resin storage chamber 6 to the die slit 12 side is constituted.

  As shown in FIG. 3, the parison P that hangs down in a tube shape has a core back contact surface (region S surrounded by oblique lines) that contacts an internal die 35 of a second molding die 33 described later. Further, the portion around the core back contact surface S is the stretched portion X where the hollow molded body is partially stretched and thinned by the core back of the internal die 35 to reduce the rigidity.

  FIG. 4 is a longitudinal sectional view showing the configuration of the injection molding apparatus 30 according to this embodiment. The injection molding apparatus 30 has a molding die 31. The mold 31 includes a first mold 32 and a second mold 33. Connected to the first mold 32 is an injection machine (injection means) 40 of a foamed resin M (see FIG. 5), which is a raw material inside the molded product. Further, the first mold 32 is provided with a hollow blow pin (shaping means) 41 for blowing gas into the parison P sandwiched between the molds 31 so as to freely advance and retract. Here, the first mold 32 has a built-in block body 43 that opens and closes the injection port 40 a of the resin injection machine 40. The block body 43 is moved up and down by an appropriate actuator (for example, an electromagnetic valve) 42. The illustrated example shows a state in which the block body 43 is moved to the upper position and the injection port 40a is closed. The inner surface of the block body 43 faces a recessed hole 44 formed in the first mold 32.

  On the other hand, the second molding die 33 of the molding die 31 includes an outer peripheral die 34 that contacts the outer peripheral mating surface of the first molding die 32 at the time of clamping, and a direction close to the first molding die 32 with respect to the outer peripheral die 34 or An internal die 35 that is relatively movable in a direction away from the first molding die 32 is provided.

  In addition, the outer peripheral die 34 is provided with projecting dies 36... 36 over the entire circumference of the outer peripheral die 34. The protruding mold 36 can be protruded from the forming mold 31 into the forming mold 31 or retracted from the forming mold 31 by an actuator (not shown). As will be described later, the projecting mold 36 is projected toward the resin molded product A remaining in the mold 31 to form a recess on the surface of the resin molded product A.

  Next, a method for molding the resin molded product A according to this embodiment will be described. Here, the resin molded product A according to the present embodiment is used, for example, for an interior / exterior member of an automobile, and as shown in FIG. 5, the inside is a foamed resin M (resin after being foamed). The resin before foaming (foamable resin) is made of the symbol M ′ (see FIGS. 8 and 9), and the surface layer portion is made of solid resin N. In that case, in the stretched portion X of the resin molded product A, the protruding molds 36... 36 protrude into the mold 31, thereby forming recesses Y. ing.

  First, in the extrusion molding apparatus 1 shown in FIG. 1 and FIG. 2, a tube-shaped parison P in a molten state is molded from a solid resin N as a raw material (see FIG. 3: parison molding process).

  Next, as shown in FIG. 6, the molded parison P is sandwiched between the molding dies 31. That is, the first mold 32 and the second mold 33 are clamped. Next, as shown in FIG. 6, gas is blown into the inside of the parison P sandwiched between the molding dies 31 and shaped into a predetermined shape (shaping step).

  Here, the blow pin 41 advances into the cavity as indicated by an arrow a, and gas (typically air) is blown into the parison P. A part of the swelled parison P enters the concave hole 44 formed in the first mold 32 and is thinly stretched. As described above, the core back contact surface S of the parison P is in contact with the internal mold 35 of the second mold 33.

  Next, as shown in FIG. 7, the actuator 42 is operated to move the block body 43 to the lower position as indicated by the arrow b. Thereby, it enters into the concave hole 44 formed in the first mold 32, and a part of the parison P that has been thinly stretched is further thinned and ruptured, and the resin injection machine 40 is placed inside the hollow molded body. A hole for injecting the foamable resin M ′ is generated through the injection port 40a.

  Next, as shown in FIG. 8, the foamed resin M ′ in a molten state is injected into the hollow molded body while leaving the obtained hollow molded body inside the molding die 31 (injection step). At this time, the foamable resin M ′ in the melted state is blown from the resin injection machine 40 through the injection port 40a, the recessed hole 44, and a hole formed by rupturing a part of the hollow molded body. It is injected into the body. At this stage, the blow pin 41 is retracted from the cavity as indicated by an arrow c.

  Next, as shown in FIG. 9, after injection of the molten foamable resin M ′, the foamable resin M ′ is foamed while the mold 31 is opened by a predetermined amount, and the resin M ′ is filled into the hollow molded body. (Filling step). That is, in FIG. 6 to FIG. 8, the mold 31 is clamped in a state where the inner mold 35 of the second mold 33 is moved in the direction close to the first mold 32, but in FIG. In a state where the mold 31 is clamped (that is, in a state where the first mold 32 and the outer peripheral mold 34 of the second mold 33 are in contact with each other), only the inner mold 35 is separated from the first mold 32 (arrow) e) is moved by a predetermined amount (core back) (not shown, but the device that cores the mold 31 in this way corresponds to “filling means” in the claims). By performing this core back, the thickness of the molded product increases and the specific gravity decreases, and the foaming of the foamed resin M is promoted, and fine bubbles are uniformly dispersed inside the molded product. Thereby, the rigidity of a molded product improves and weight reduction is achieved. Furthermore, since the surface layer portion is composed of the solid resin (non-foamed resin) N, bubbles do not appear in the surface layer portion, and the appearance of the finally obtained resin molded product A can be improved.

  Further, the core back stretches a portion of the hollow molded body located at the boundary between the outer peripheral die 34 and the inner die 35 of the second molding die 33 (stretched portion X: see FIG. 3).

  In addition, when filling the foamable resin M ′, as shown by an arrow d in FIG. 9, the air is removed from the hollow molded body through the hollow blow pin 41 in the retracted state.

  In addition, the resin injection machine 40 and the injection port 40 a or the recessed hole 44 are disposed in the central portion of the first mold 32. As a result, as shown in FIGS. 8 and 9, the foamable resin M ′ is injected from the front portion of the mold 31. Thereby, the flow distance in the cavity of the injected foamable resin M ′ is averaged, and the foamed resin M is uniformly filled inside the hollow molded body.

  Next, as shown in FIG. 10, the obtained resin molded product A is formed on the surface of the portion where the hollow molded body is stretched (the stretched portion X) by core-backing the internal mold 35 in the filling step. Recesses Y ... Y that immerse inside are formed (recess formation step). That is, the projecting molds 36... 36 provided in the outer peripheral mold 34 are projected toward the resin molded product A remaining in the mold 31 as indicated by an arrow m, thereby forming a recess on the surface of the resin molded product A. Is.

  More specifically, as shown in FIG. 11A, immediately after the core back, the stretched portion X of the hollow molded body is thinned, and the protruding mold 36 faces the hollow molded body at a position corresponding to the stretched portion X. It is out. Next, as shown in FIG. 11B, when the protruding mold 36 protrudes into the mold (arrow m), the protruding mold 36 pushes the stretched portion X of the thin hollow molded body toward the inside of the molded product. As a result, a recess Y is formed on the surface of the resin molded product A as shown in FIG.

  In addition, many protrusion type | molds 36 are comprised over the perimeter of an outer periphery type | mold, and many recessed parts Y are formed over the perimeter of the side surface of the resin molded product A in connection with it.

  As described above, as shown in FIG. 5, the inside is made of the foamed resin M, the surface layer portion is made of the solid resin N, and the concave portion Y. The formed resin molded product A is finally molded.

  Thus, in this embodiment, in order to ensure good moldability of the primary hollow molded body and to ensure good appearance and rigidity of the final molded product A, the parison P ( 3) is sandwiched between molds 31 and a hollow molded body (see FIGS. 6 and 7) obtained by blowing gas into the interior and shaping into a predetermined shape is left in the mold 31 in a molten state. The foamable resin M ′ is injected into the hollow molded body (see FIG. 8), and then the foamable resin M ′ is foamed while the molding die 31 is opened (core back) to hollow the resin M ′. Since the molded body is filled (see FIG. 9), foaming of the foamed resin M is sufficiently promoted, and lightness and rigidity are improved.

  In addition, in the obtained resin molded product A, a portion in which the hollow molded body is stretched and thinned by opening the molding die 31 by a predetermined amount (core back) (the stretched portion X of the hollow molded body, the thinned portion). Since the concave portion Y that immerses into the inner side of the resin molded product A is formed on the surface, even if the surface layer portion constituted by the hollow molded body is partially stretched and thinned, the stretched portion X Further, it is possible to easily and effectively prevent the rigidity of the thinned portion from being lowered as compared with the case where the concave portion Y is not formed.

  Furthermore, since the surface layer portion is made of solid resin (non-foamed resin) N, bubbles do not appear in the surface layer portion, and the appearance can be improved. Therefore, the degree of foaming of the internal foamed resin M covered with the surface layer portion made of the solid resin N is sufficiently enhanced, and the partial rigidity of the surface layer portion is prevented from being lowered, and the appearance, lightness, and rigidity are excellent. The resin molded product A can be obtained easily and reliably. [Configuration equivalent to claim 1]

  In that case, as shown in FIG. 10, the molding die 31 is formed with the recess Y formed on the surface of the stretched portion X of the hollow molding body while the obtained resin molded product A is left in the molding die 31. Since the projecting mold 36 is projected from the mold 31 toward the resin molded product A, the concave portion Y can be continuously formed before the mold is opened to take out the resin molded product A from the mold 31. Productivity is improved. In addition, during the period in which the stretched portion (thinned portion) X of the surface layer portion constituted by the hollow molded body still retains flexibility at a high temperature before the resin molded product A cools down, Since the protruding mold 36 protrudes toward the product A, when the surface layer portion made of the solid resin N is pushed by the protruding mold 36, as shown in FIG. Thus, the problem that the surface layer portion is broken by the protruding mold 36 and the foamed resin M inside can be seen can be avoided. [Configuration equivalent to claim 2]

  In addition, one of the molds 31 (second mold 33) has an outer peripheral mold 34 that contacts the outer peripheral mating surface of the other mold 31 (first mold 32) when the mold is clamped. It has an internal mold 35 that is relatively movable in the direction close to the first mold 32 or in the direction away from the first mold 32, and when the parison P is shaped (see FIGS. 6 and 7) and foaming At the time of injection of the expandable resin M ′ (see FIG. 8), the mold 31 is clamped in a state where the internal mold 35 is moved in the direction close to the first mold 32, and the foaming resin M ′ is expanded. At the time of filling (see FIG. 9), since the inner mold 35 is moved in the direction (arrow e) away from the first mold 32 while the mold 31 is clamped, the structure of the mold 31 and its Without complicating the drive mechanism and the like, the mold 31 is opened by a predetermined amount with a simple configuration. The core back) it becomes possible.

  Moreover, at the time of forming the concave portion, as shown in FIG. 10, the protruding die 36 provided on the outer peripheral die 34 is used as the forming die while the internal die 35 is moved in the direction away from the other 32 of the forming die 31 (arrow e). Since the protrusion 31 is made to project, the concave portion Y can be reliably formed using the projecting die 36 aiming at an appropriate portion of the parison P (the stretched portion X of the hollow molded body, the thinned portion). Therefore, it is possible to more surely avoid the partial rigidity reduction of the surface layer portion. [Configuration equivalent to claim 3]

  Here, it is preferable that the foamable resin M contains reinforcing fibers such as glass fibers. When the mold 31 is core-backed, a springback phenomenon of the reinforcing fiber occurs, and thereby foaming of the foamed resin M is further promoted. [Configuration corresponding to claim 4]

  The foamable resin M preferably contains a physical foaming agent. Due to the effect of the physical foaming agent, the foamed cell diameter inside the molded product A can be made smaller, and the rigidity of the resin molded product A is further improved. [Configuration corresponding to claim 5]

  In that case, it is preferable to use a fluid in a supercritical state as the physical foaming agent. By the function of the fluid in the supercritical state, the diameter of the foam cell inside the molded product A can be made to be a finer diameter, and the rigidity of the resin molded product A is further improved. [Configuration equivalent to claim 6]

  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, it can move actively in the molten resin, and can be diffused and penetrated deeply into the resin molecules to become a fine foam seed.

  For the solid resin N that is the raw material of the parison P and the foamable resin M that is the raw material inside the molded product, thermoplastic resins are preferably used. For example, polyethylene (PE), polypropylene (PP), ABS resin, nylon resin Etc. are suitable.

  By the way, in this invention, although the shape of the recessed part Y is not specifically limited, such as cylindrical shape and polygonal shape, arrangement | positioning of typical recessed part Y, and various force (bending, tension | pulling, compression) which act on the resin molded product A A preferable relationship with the above will be described with reference to FIG.

  The aspect 1 of the recessed part Y arrangement | positioning of FIG. 12 has one recessed part Y extended and formed in the length direction of the side surface in one side surface of the molded article A, and aspect 2 has several recessed part Y ... Y Is formed on one side surface of the molded product A so as to extend in the length direction of the side surface. In the aspect 3, a plurality of concave portions Y ... Y are formed on one side surface of the molded product A in the length direction of the side surface. In the aspect 4, the overlap in the width direction is shifted in the aspect 3, and in the aspect 5, the plurality of recesses Y ... Y are formed on one side surface of the molded product A. , Formed by extending in the width direction of the side surface, Aspect 6 is formed by forming a plurality of recesses Y ... Y on one side surface of the molded product A in the width direction of the side surface and overlapping in the width direction. Aspect 7 is the same as aspect 6, in which the overlap in the width direction is shifted.

  With respect to the bending force acting on the resin molded product A, the aspect 4 is preferable because it is hardly deformed. Hereinafter, in order of preference, they are Aspect 3, Aspect 1, Aspect 2, Aspect 7, Aspect 6, Aspect 5. For the tensile force 1 (tensile in the width direction of the side surface) acting on the resin molded product A, the aspect 7 is preferable because it is hardly deformed. Hereinafter, it is Aspect 6 and Aspect 5 in order of preference. For the tensile force 2 (tensile in the length direction of the side surface) acting on the resin molded product A, the mode 1 is preferable because it is hardly deformed. Hereinafter, in order of preference, they are Aspect 4, Aspect 3, and Aspect 2. For the compressive force 1 (compression in the width direction of the side surface) acting on the resin molded product A, the aspect 7 is most difficult to be deformed. Hereinafter, it is Aspect 6 and Aspect 5 in order of preference. For the compressive force 2 (compression in the length direction of the side surface) acting on the resin molded product A, the aspect 4 is preferable because it is most difficult to deform. Hereinafter, in order of preference, they are Aspect 3, Aspect 1, and Aspect 2.

  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, another method for forming a hole in the hollow molded body for injecting the foamable resin M in the hollow molded body is shown in FIGS. 13 and 14 (the same reference numerals are used for the same or similar members as described above). ). FIG. 13 shows that the protrusion 32a is raised around the recessed hole 44 of the first molding die 32, and a part of the hollow molded body is meandered to be thin (the state shown in FIG. 13 (a)). By pulling 43 as indicated by arrow f (state of FIG. 13 (b)), a part of the hollow molded body is more reliably ruptured, and the hollow molded body is inserted through the generated hole, the injection port 40a and the like. The foamable resin M is injected inside. FIG. 14 shows the same concept, but in the case of FIG. 13, a part of the hollow molded body is stretched in the same direction in the state of FIG. 13 (a) and the state of FIG. 13 (b) to be ruptured. On the other hand, in the case of FIG. 14, the tip of the block body 43 is protruded from the protrusion 32a, and a part of the hollow molded body is reversed in the state of FIG. 14 (a) and the state of FIG. 14 (b). It is different in that it is stretched to burst.

  FIGS. 15, 16 and 17 show a method for forming a hole in the hollow molded body for venting air in the hollow molded body when foaming resin M is foamed and filled (for the same or similar members as described above). 15, the air discharge path 51 and the moving body 52 having the projecting pins 53... 53 are built in the first mold 32, and gas is blown into the parison P by the blow pins 41. At the time of (arrow a), the projecting pins 53... 53 are projected into the cavity to make a hole in the hollow molded body (state shown in FIG. 15A). Is retracted as indicated by an arrow g to retract the projecting pins 53... 53 from the cavity (the state shown in FIG. 15B), and the holes formed in the hollow molded body and the through holes 54... 54 of the pins 53. Hollow molded body through air discharge path 51 16 and 17, on the other hand, each of the air discharge path forming hole 61 or the air discharge path forming recess 71 is formed as a molding die (in the example shown, the first molding die). 32) is provided in the outer peripheral mating surface portion in the case of Fig. 16. In the case of Fig. 16, the core columnar body 62 is inserted into the air discharge path forming hole 61 (in the state of Fig. 16A), and in this state. Then, mold clamping to air blow (state shown in FIG. 16 (b)), the core columnar body 62 is pulled out when the foamable resin M is injected (state shown in FIG. 16 (c)), and air is released from the through hole. On the other hand, in the case of Fig. 17, pin bodies 72 ... 72 are inserted into the upper surface of the air discharge passage forming recess 71 (the state of Fig. 17 (a)), and in this state, the mold clamping is performed. ~ Air blow (state shown in Fig. 17 (b)) and pin when foaming resin M is injected 72 ... 72 by far the (state of FIG. 17 (c)), is from the loophole and the pin holes 73 ... 73 to perform air bleeding.

  As described above in detail with reference to specific examples, the present invention sufficiently enhances the degree of foaming of the internal foamed resin covered with the surface layer portion made of the non-foamed resin, and is composed of the primary hollow molded body. Because it is a technology that can provide a resin molded product that is excellent in appearance, lightness, and rigidity by avoiding partial reduction in rigidity of the surface layer and avoiding the appearance of bubbles in the surface layer. In the technical field of resin molding, a wide range of industrial applicability is expected.

It is a longitudinal cross-sectional view which shows the structure of the extrusion molding apparatus of the parison based on the best embodiment of this invention. It is the II-II sectional view taken on the line of FIG. 1 is a perspective view of a parison according to a preferred embodiment of the present invention. It is a longitudinal section showing the composition of the injection molding device concerning the best embodiment of the present invention. 1 is a partially cutaway perspective view showing the structure of a resin molded product according to a best embodiment of the present invention. FIG. 5 is a longitudinal sectional view similar to FIG. 4 for explaining the molding method of the resin molded product step by step, and shows the next step of FIG. 4 (shaped step). Similarly, it is a longitudinal sectional view similar to FIG. 4 and shows the next stage of FIG. 6 (shaping step). FIG. 9 is a longitudinal sectional view similar to FIG. 4 and shows the next stage of FIG. 7 (injection process). FIG. 9 is a longitudinal sectional view similar to FIG. 4 and shows the next stage of FIG. 8 (filling step). FIG. 10 is a longitudinal sectional view similar to FIG. 4 and shows the next stage of FIG. 9 (concave forming step). It is a principal part enlarged view which shows a recessed part formation process in steps, (a) is a state immediately after a core back, (b) is a state in which a protruding mold protrudes toward a resin molded product, and (c) is a resin molded product. Each shows a state in which a recess is formed. It is explanatory drawing which shows the preferable relationship between the various aspects (Aspect 1-Aspect 7) of recessed part arrangement | positioning, and the various force (bending, tension | tensile_strength, compression) which acts on a resin molded product. It is explanatory drawing of another method of forming the hole for injecting a foamable resin inside a hollow molded object in a hollow molded object. It is explanatory drawing similar to FIG. It is explanatory drawing of the method of forming the hole for performing air bleeding in a hollow molded object at the time of foaming and filling of a foamable resin in a hollow molded object. It is explanatory drawing similar to FIG. It is explanatory drawing similar to FIG.

Explanation of symbols

1 Extrusion molding equipment (Parison molding means)
8 Solid resin extruder 12 Die slit 30 Injection molding device 31 Mold 32 First mold (the other mold)
33 Second mold (one of the molds)
34 Peripheral mold 35 Internal mold 36 Projection mold (concave forming means)
40 Foamable resin injection machine (injection means)
41 Blow pins (shaping means)
A resin molded product P parison X stretched part, thinned part Y concave

Claims (11)

A molding method of a resin molded product in which the inside is made of foamed resin and the surface layer part is made of solid resin,
A parison molding process for molding a parison with the solid resin;
A shaping process in which the molded parison is sandwiched between molds and a gas is blown into the interior to form a predetermined shape;
An injection step of injecting a molten foamable resin into the hollow molded body, with the obtained hollow molded body left in the mold,
After injection, a filling step of expanding the foamable resin while opening the mold by a predetermined amount and filling the resin into the hollow molded body;
A recess forming step of forming a recess that immerses into the inner side of the obtained resin molded product on the surface of the stretched portion of the hollow molded body by opening the molding die by a predetermined amount in the filling step. A molding method of a resin molded product characterized by the above. A method for molding a resin molded product according to claim 1,
The formation of the recess in the recess forming step is performed by projecting a protruding mold from the mold toward the resin molded product while leaving the obtained resin molded product in the mold. Molding method for resin molded products. A method for molding a resin molded product according to claim 2,
One of the molding dies is in contact with the other outer peripheral mating surface of the molding die at the time of clamping, and is separated from the outer die in a direction adjacent to the other of the molding dies or the other of the molding dies. It has an internal mold that is relatively movable in the direction,
In the shaping step and the injection step, the mold is clamped in a state where the internal mold is moved in a direction close to the other of the molds,
In the filling step, in a state where the mold is clamped, the internal mold is moved away from the other mold,
In the recess forming step, the resin mold is characterized in that the protruding mold provided in the outer peripheral mold is protruded into the mold while the internal mold is moved away from the other mold. Molding method. A method for molding a resin molded product according to any one of claims 1 to 3,
In the injection step, a foamable resin containing reinforcing fibers is injected, and a method for molding a resin molded product is provided. A method for molding a resin molded product according to any one of claims 1 to 4,
In the injection step, a foamable resin containing a physical foaming agent is injected. A method for molding a resin molded product according to claim 5,
In the injection step, a foamable resin containing a fluid in a supercritical state is injected as the physical foaming agent. A molding device for a resin molded product, the inside of which is made of foamed resin and the surface layer portion is made of solid resin,
A parison molding means for molding a parison with the solid resin;
A mold that sandwiches the parison molded by this parison molding means,
Shaping means for blowing gas into the inside of the parison sandwiched between the molding dies and shaping it into a predetermined shape;
Injection means for injecting a foamed resin in a molten state into a hollow molded body in the mold obtained by the shaping means;
After the injection of the foamable resin by the injection means, a filling means for filling the hollow molded body with the foamable resin by foaming the foamable resin while opening the molding die by a predetermined amount;
During filling of the foamable resin by the filling means, a concave portion that immerses into the inner side of the obtained resin molded product is formed on the surface of the portion where the hollow molded body is stretched by opening a predetermined amount of the mold. An apparatus for molding a resin molded product, comprising: a recess forming means for forming. A molding apparatus for a resin molded product according to claim 7,
The recess forming means has a protruding mold that can freely protrude from the mold into the mold, and forms the recess by protruding the protruding mold toward a resin molded product remaining in the mold. An apparatus for molding a resin molded product, characterized in that A molding apparatus for a resin molded product according to claim 8,
One of the molding dies is in contact with the other outer peripheral mating surface of the molding die at the time of clamping, and is separated from the outer die in a direction adjacent to the other of the molding dies or the other of the molding dies. It has an internal mold that is relatively movable in the direction,
The molding die is in a mold-clamping state in a state where the internal die moves in a direction close to the other of the molding die at the time of shaping by the shaping means and at the time of injection by the injection means,
The mold is moved in a direction in which the internal mold is separated from the other of the mold in the clamped state when being filled by the filling means,
When the concave portion is formed by the concave portion forming means, the protruding die provided in the outer peripheral die protrudes into the forming die in a state where the inner die is moved away from the other of the forming die. An apparatus for molding a resin molded product. A molding apparatus for a resin molded product according to any one of claims 7 to 9,
The said injection | pouring means inject | pours the foamable resin containing a physical foaming agent, The molding apparatus of the resin molded product characterized by the above-mentioned. A molding apparatus for a resin molded product according to claim 10,
The said injection | pouring means inject | pours the foamable resin containing the fluid of a supercritical state as the said physical foaming agent, The molding apparatus of the resin molded product characterized by the above-mentioned.

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