JP2008173829A - Method and apparatus for molding resin molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accelerate the foaming of a molten resin by the core back of a mold and to suppress the lowering of the followability to the inner wall of a mold of a parison. <P>SOLUTION: This molding method of a resin mold product has a process for clamping molds 21 and 22 so that an extrusion molded non-foamable and stretchable cylindrical molding P is arranged in the cavity C formed by the molds 21 and 22, an injection process for injecting the foamable molten resin in the cylindrical molding P within the cavity C in a state that the cylindrical molding is expanded in the cavity C to mold a blow molding P and a foaming process for foaming the molten resin in the cylindrical molding in the blow molding P while increasing the volume of the cavity C by the core back of the molds 21 and 22. In the foaming process, the temperature of the molten resin charged in the region (part B) approaching the part to be stretched of the blow molding P stretched accompanied by the increase in the volume of the cavity C due to the core back is set higher than that of the molten resin charged in another region. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a molding technique for a resin molded product.

  As a conventional molding technique for resin molded articles, a foam molded article with a skin is obtained by filling a thermoplastic resin foam piece inside a hollow molded article formed by blow molding a parison having a thermoplastic resin foam layer and heating it. A manufacturing method has been proposed (for example, Patent Document 1). According to this method, a molded product having a smooth surface and high strength can be produced.

  Also, as another molding technology for foamed molded products, a method of promoting foaming of a resin while filling the mold with a foamable resin and core-backing the mold to increase the volume of the cavity in the mold Has been proposed. According to this method, a lightweight and high-strength molded product can be produced, but there is a problem that surface smoothness is inferior.

Therefore, by combining the above-described molding method of the foamed article with skin and the molding method using the core back of the mold, a molded product having a smooth surface, light weight and high strength can be obtained.
JP 2004-284149 A

  Here, when foam-molded with a skin is foam-molded with a core back of the mold, the skin material (parison) is blown in the cavity before the core back of the mold, thereby closely contacting the inner wall of the mold. Thereby, since a parison is cooled gradually, the ductility of a parison falls. When the mold is core-backed in this state, the tension is increased because the parison with reduced ductility is stretched near the inner wall of the mold that appears along with the core back. For this reason, foaming of the molten resin due to the core back is suppressed, and the followability of the parison to the inner wall of the mold is lowered.

  The present invention has been made in view of the above problems, and an object of the present invention is to promote foaming of a molten resin by a core back of a mold and to suppress a decrease in followability of the parison to the mold inner wall.

  In order to solve the above-mentioned problems and achieve the object, in the invention according to claim 1, a mold is formed so that an extruded non-foaming and stretchable cylindrical molded body is disposed in a cavity of the mold. And an injection step of injecting a foamable molten resin into the blow molded body in the cavity in a state where the tubular molded body is expanded in the cavity to form a blow molded body, and A foaming step of foaming the molten resin inside the blow molded body while increasing the volume of the cavity by core-backing the mold, and in the foaming step, the volume of the cavity by the core back is increased. Compared with the temperature of the molten resin filled in the other part, the temperature of the molten resin filled in the part close to the stretched part of the blow molded body that is stretched with the increase Ku molding method of a resin molded article and setting is provided.

  Further, in the present invention according to claim 9, the mold movable mechanism for performing the core back operation for clamping and opening the mold and increasing the volume of the cavity, and the non-foaming and stretchable cylindrical shape An extrusion molding machine for extruding the molded body, and a foamable molten resin inside the blow molded body in the cavity in a state where the cylindrical molded body is expanded in a cavity in a mold-clamped state to form a blow molded body An injection machine for injecting the molten resin, and at the time of foaming of the molten resin, the molten resin filled in a portion close to the stretched portion of the blow molded body that is stretched as the volume of the cavity is increased by the core back There is provided a molding apparatus for a resin molded product, characterized by comprising temperature setting means for setting the temperature higher than the temperature of the molten resin filled in other parts.

  According to the first and ninth aspects of the present invention, when the molten resin is foamed, it is close to the stretched portion of the blow molded body that is stretched as the volume of the cavity is increased by the core back. Since the temperature of the molten resin filled in the part is set higher than the temperature of the molten resin filled in the other part, the temperature in the stretched part of the blow molded article can be increased. That is, it is possible to suppress a decrease in ductility at the stretched portion of the blow molded article. Therefore, foaming of the molten resin can be promoted by the core back of the mold, and the followability of the blow molded body to the inner wall of the mold can be improved.

  In the invention which concerns on Claim 2 and Claim 10, with the heater provided in the injection machine which injects the said molten resin, the temperature of the said molten resin which exists in the said injection machine is compared with another site | part on the injection port side. May be set higher. According to this configuration, foaming of the molten resin can be promoted by a core back of the mold, and followability of the blow molded body with respect to the inner wall of the mold can be improved with a simple configuration.

  Moreover, in the invention which concerns on Claim 3 and Claim 11, in the injection machine which injects the said molten resin, the said molten resin from which a cooling rate differs is made to exist, and the said molten resin which exists in the injection port side is in another part. It may have a characteristic that the cooling rate is slower than that. According to this structure, since the molten resin having a slow cooling rate is injected into a portion close to the stretched portion, it is possible to suppress a reduction in foaming at the portion.

  Further, in the inventions according to claim 4 and claim 12, temperature setting means for controlling the temperature of a portion of the mold adjacent to the stretched portion of the blow molded body is provided, and after the core back, during the time of demolding In at least a partial period of time, the temperature setting means may set the temperature of the portion of the mold adjacent to the stretched portion of the blow molded body to be lower than that of other portions. According to this configuration, in at least a part of the period after the core back and at the time of demolding, the temperature of the part close to the stretched part of the blow molded body is set lower than the other parts, so that the foaming is stopped. Solidification of the molten resin thus obtained can be promoted.

  Moreover, in the invention which concerns on Claim 5 and Claim 13, the said temperature setting means carries out the medium temperature-adjusted to the flow path formed in the site | part close | similar to the to-be-stretched part of the said blow molding body in the said metal mold | die. The temperature may be set by circulation. According to this configuration, it is possible to easily and easily adjust the temperature of the portion of the mold that is close to the stretched portion of the blow molded body.

  Moreover, in the invention which concerns on Claim 6 and Claim 14, the reinforcing fiber may contain in the said foamable molten resin. According to this configuration, the strength of the resin molded product can be improved by a simple and easy treatment of containing the reinforcing fiber in the foamable molten resin.

  Moreover, in the invention which concerns on Claim 7 and Claim 15, the physical foaming agent may contain in the said foamable molten resin. According to this configuration, fine foam cells can be formed inside the resin molded product, and the strength of the resin molded product can be increased.

  In the inventions according to claims 8 and 16, the physical foaming agent may be a fluid in a supercritical state. In this case, a finer foam cell can be formed.

  ADVANTAGE OF THE INVENTION According to this invention, while foaming of molten resin is accelerated | stimulated by the core back of a metal mold | die, the fall of the followable | trackability with respect to the metal inner wall of a parison can be suppressed.

<Common overall configuration>
FIG. 1 is a schematic configuration diagram of an injection molding apparatus A according to an embodiment of the present invention. The injection molding apparatus A includes an extruder 10 that extrudes a parison P that is a non-foaming and stretchable cylindrical molded body, and a molding machine 20 that is disposed below the extruder 10.

  The extruder 10 is a device that extrudes the parison P and hangs it down between the mold cavities in the mold open state. Examples of the non-foamable molten resin constituting the parison P include polypropylene. Here, the parison P includes both the state of the cylindrical molded body extruded by the extruder 10 and the state of the blow molded body in which the cylindrical molded body is expanded in the cavity.

  The molding machine 20 includes a set of molds 21 and 22 that constitute a mold part, and hydraulic actuators 23 and 24 that move the molds 21. The mold 21 includes a frame-shaped main body portion 21a having a rectangular opening, and a core portion 21b inserted into the opening of the main body portion 21a. The core portion 21b is movable relative to the mold 22 and forms a cavity with the mold 22 when the mold is clamped. The main body portion 21a is disposed on the outer periphery of the core portion 21b, contacts the core portion 21b and the mold 22 at the time of mold clamping, and part of the cavity while being separated from the mold 22 with the core back operation of the core portion 21b. Form. The hydraulic actuator 23 is configured to be able to move independently of the main body portion 21a and the core portion 21b. For example, when the mold is clamped or opened, both the main body portion 21a and the core portion 21b are moved forward or backward. Further, when performing the core back operation to increase the volume of the cavity, only the core portion 21b is moved backward. Thereby, it is possible to cause the mold to perform a desired operation.

  A blow nozzle 25 is detachably attached to the mold 22. The blowing nozzle 25 is configured to be movable by a driving means (not shown), and is moved between a blowing position protruding inward of the mold 22 and a retracted position separated from the inside. The blowing nozzle 25 is a nozzle for blowing the compressed gas supplied from the compressed gas supply device 26 into the parison P to inflate it. The supply device 26 includes, for example, a compressor and a control valve that switches between sending and shutting off compressed gas.

  An injection machine 27 for injecting foamable molten resin is mounted on the mold 22. The injection machine 27 injects the molten resin into the parison P in a state where the parison P is inflated in the mold-clamped cavity through the injection port 27 c and the resin passage 22 a formed in the mold 22.

  A foaming agent supply device 28 is connected to the injection machine 27. The foaming agent supply device 28 includes a supercritical gas generator 28a and a cylinder 28b. The foaming agent supply device 28 is a device that changes a gas such as carbon dioxide gas or nitrogen gas filled in the cylinder 28b to an inert gas in a supercritical state. The supercritical gas generated by the foaming agent supply device 28 is introduced into the screw cylinder 27b of the injection machine 27 as a foaming agent and is dissolved in a molten resin (for example, polypropylene) in the screw cylinder 27b. Generated.

  Next, a method for molding a resin molded product by the injection molding apparatus A will be described with reference to FIGS. First, as shown to Fig.2 (a), the parison P is extruded and drooped from the extruder 10. FIG. Subsequently, the molds 21 and 22 are clamped, and the parison P is placed in the cavity C formed by the molds 21 and 22.

  Next, as shown in FIG. 2B, the parison P is expanded in the cavity C in the molds 21 and 22 by blowing out compressed gas from the blowing nozzle 25. The parison P swells in close contact with the inner wall surfaces of the molds 21 and 22 by blowing the compressed gas.

  Next, as shown in FIG. 3A, the foamable molten resin R is injected from the injection machine 27 through the resin passage 22a. By injection of the molten resin R, a part of the parison P is broken and perforated, and the expanded resin R is filled into the swelled parison P.

  When filling the molten resin R, the air in the parison P is discharged by opening the blowing nozzle 25 to the atmosphere, and the filling efficiency of the molten resin R is increased. It is also possible to further increase the filling efficiency of the molten resin R by sucking the air in the parison P from the blowing nozzle 25.

  As shown in FIG. 3 (b), when the blowing nozzle 25 is moved to the retracted position and the filling of the molten resin R is completed, the core portion 21b is core-backed as shown in FIG. Increase space. Thereby, foaming of the molten resin R is promoted. However, when performing the core back, a portion B (extended portion) of the parison P adjacent to the periphery of the surface facing the cavity C of the core portion 21b may be peeled off from the close contact state with the mold. is there. That is, the normal shape of the resin molded product cannot be obtained in the portion B unless the peeled portion comes into close contact with the main body portion 21a again due to the foaming action of the molten resin. Means for solving this problem will be described in detail in an embodiment described later.

  In the present embodiment, an example in which supercritical gas is used as the foaming agent mixed in the molten resin R has been described. However, the foaming agent is not limited to this, and other types of foaming agents may be used. However, the physical foaming agent can form fine foam cells inside the solid resin molded product X, and the strength of the solid resin molded product X can be increased, compared with the chemical foaming agent. Further, among the physical foaming agents, finer foam cells can be formed by using a supercritical fluid as in the present embodiment.

  In addition, as molten resin R, the thing containing a reinforcement fiber (for example, glass fiber, carbon fiber, etc.) is employable. By mixing the reinforcing fiber, the internal stress of the reinforcing fiber forcedly aligned along the flow direction is released along with the core back based on the resin flow before the core back, and the orientation is released. As a result, the apparent volume of the molten resin R increases (spring back phenomenon), and the foaming of the molten resin R can be further promoted.

<Other examples of air discharge when filling molten resin>
In the above embodiment, when the molten resin R is filled, the air inside the parison P is discharged by the blowing nozzle 25. However, a configuration in which a perforating apparatus that perforates the parison P is provided may be employed. FIG. 4 is an explanatory view showing an example using the punching device 30.

  As shown in FIG. 4A, in this example, a punching device 30 is attached to the mold 22. The punching device 30 includes a piston 31 provided with a pin 31a protruding therefrom, and an actuator 32 for sliding the piston 31. The mold 22 is formed with a sliding space 22 c of the piston 31 and a communication path 22 b that allows the sliding space 22 c to communicate with the outside of the mold 22. Further, there is a hole communicating with the sliding space 22 c and opened in the inner wall surface of the mold 22, and a pin 31 a is inserted into the hole so that the pin 31 a protrudes inward of the mold 22.

  As shown in FIG. 4B, when compressed gas is blown into the parison P from the blow nozzle 25 and is expanded, a hole is formed in a part of the parison P due to the presence of the pin 31a protruding into the cavity C.

  As shown in FIG. 4C, when the piston 31 is moved backward by operating the actuator 32, the hole of the parison P, the hole 22d in which the pin 31a is inserted, the sliding space 22c and the communication path 22b are used as the flow paths. The air in the parison P can be discharged to the outside of the mold 22. Thus, when the molten resin R is filled into the parison P from the injector 27, the air in the parison P is discharged to the outside and the filling efficiency is increased.

<Other examples of perforation of parison P during filling with molten resin>
In the above embodiment, when the molten resin R is filled, a part of the parison P is perforated by the filling pressure, and the molten resin R is filled in the swelled parison P (FIG. 3A). 5 and 6 are explanatory views showing an example using the punching device 40. FIG.

  As shown in FIG. 5A, in this example, a punching device 40 is attached to the mold 22. The mold 22 has a through hole 22e and a resin passage 22f that allows the through hole 22e and the injection machine 27 to communicate with each other.

  The punching device 40 slides in the through hole 22e, and opens and closes the shutter member 41 that opens and closes the resin passage 22f, the actuator 42 that slides the shutter member 41, the shutter member 43 that opens and closes the through hole 22e, and the shutter member 43. And an actuator 44 to be operated.

  As shown in FIG. 5B, when the compressed gas is blown into the parison P from the blow nozzle 25 and is expanded, the shutter member 41 closes the resin passage 22f, and the shutter member 43 closes the through hole 22e. ing. When the parison P swells, as shown in FIG. 6A, a part of the parison P enters the through hole 22e to form a convex thin portion P '. The thin portion P ′ is formed by being stretched and thinned when the parison P enters the through hole 22 e.

  At this time, when the actuator 44 is operated to lower the shutter member 43, the thin portion P ′ is ruptured by the pressure of the compressed gas from the blowing nozzle 25, and the parison P is perforated as shown in FIG. Is done.

  Thereafter, as shown in FIG. 6 (c), the actuator 42 is operated to retract the shutter member 41 to open the resin passage 22f (in communication with the through hole 22e). Subsequently, the molten resin R can be filled into the parison P by extruding the molten resin R from the injection machine 27. By using the punching device 40 in this way, a part of the parison P can be punched more reliably.

  FIG. 7A is a view showing a modification of the example using the punching device 40. In the example shown in the figure, the mold 22 is formed with a cylindrical portion 22g projecting inwardly. Further, the mold 22 is formed with a through hole 22e ′ communicating from the inside of the cylindrical portion 22g to the outside of the mold 22, and a resin passage 22f ′ communicating the through hole 22e ′ and the injection machine 27. A shutter member 41 'for opening and closing the resin passage 22f' and an actuator 42 'for sliding the shutter member 41' in the through hole 22e 'are disposed in the through hole 22e'.

  In the case of this example, when the compressed gas is blown into the parison P from the blow nozzle 25 and is expanded, the shutter member 41 ′ closes the resin passage 22 f ′. When the parison P swells, as shown in FIG. 7A, a part of the parison P becomes concave due to the presence of the cylindrical portion 22g, and a thin portion P ′ is formed which enters the cylindrical portion 22g and becomes convex. Is done. The thin portion P ′ is formed by being thinned by being stretched when the parison P is in close contact with the cylindrical portion 22 g and enters the through hole 22 e.

  At this time, when the actuator 42 ′ is operated to retract the shutter member 41 ′, the thin portion P ′ is ruptured by the pressure of the compressed gas from the blowing nozzle 25, as shown in FIG. Is perforated.

  As shown in FIG. 7C, the shutter member 41 ′ may be configured as a shutter member 41 ″ having a sharp tip, and the tip may protrude from the cylindrical portion 22g. The thin wall portion P ″ is formed in a concave shape in close contact with the tip surface of the shutter member 41 ″. Since the tip of the shutter member 41 is pointed and protrudes inward of the mold 22. The thin-walled portion P ″ becomes more fragile and easily broken.

<First Embodiment>
FIG. 8 is a schematic configuration diagram of an injection molding apparatus A-1 according to the first embodiment. The same reference numerals are given to the same configurations as the common overall configuration described above, and the description thereof is omitted.

  The injection machine 27 'includes a heater H on the injection port 27c' side in the resin reservoir portion between the injection port 27c 'and the screw cylinder 27b. The heater H adjusts the temperature of the molten resin existing around the injection port 27c '. In the present embodiment, the heater H sets the temperature of the molten resin present in the injection machine 27 ′ so as to increase toward the injection port 27 c ′.

  According to this configuration, the molten resin having a relatively high temperature existing on the injection port 27c ′ side of the injection machine 27 ′ can be injected first into a portion (part B) close to the stretched portion of the parison P. it can. The molten resin injected from the injection port 27c 'is cooled from the molds 21 and 22, but if the temperature of the injected molten resin is high, it takes time until the molten resin is cooled to the solidification temperature. Therefore, in the meantime, foaming in the portion B can be promoted, and a decrease in followability of the parison P with respect to the inner walls of the molds 21 and 22 can be suppressed.

  In the present embodiment, the injector 27 ′ is provided with the heater H partially on the injection port 27c ′ side of the resin reservoir portion between the injection port 27c ′ and the screw cylinder 27b. It is good also as a structure which controls the temperature of molten resin by arrange | positioning to the whole.

<Second Embodiment>
In the first embodiment, the temperature of the molten resin existing on the injection port 27c ′ side is set to be higher than that of other parts, so that the part (part B) near the stretched part of the parison P is melted. Although the temperature of the resin was adjusted, in the present embodiment, by connecting two injection machines 27 and 27 ′ to the mold 22 and providing a difference in the temperature of the molten resin injected from both, the melting of the part B Only increase the temperature of the resin. The same reference numerals are given to the same configurations as the common overall configuration described above, and the description thereof is omitted.

  FIG. 9 is a schematic configuration diagram of an injection molding apparatus A-2 according to the second embodiment. Two injection machines 27 and 27 ′ are connected to the mold 22. The injection machine 27 'is the same as that of the first embodiment, and includes a heater H on the injection port 27c' side in the resin reservoir portion between the injection port 27c 'and the screw cylinder 27b. On the other hand, the injector 27 does not include the heater H. Since the molten resin in the injection machine 27 ′ is heated by the heater H, the temperature becomes higher than that of the molten resin in the injection machine 27. The molten resin generated by the injection machine 27 'is injected from the injection port 27c'. On the other hand, the molten resin generated by the injection machine 27 is injected from the injection port 27c. The injection port 27c 'is arranged at a position where it can be injected into the portion B, and the injection port 27c is arranged at a position somewhat away from the injection port 27c'.

According to this configuration, since the molten resins having different temperatures are injected from the different injection ports 27c and 27c ′ from the injection machines 27 and 27 ′, the high-temperature molten resin R ′ can be reliably injected into the portion B. Therefore, since the high-temperature molten resin can be arranged in the portion B, the foaming of the portion B can be promoted, and the decrease in followability of the parison P with respect to the inner walls of the molds 21 and 22 can be suppressed. .
In the present embodiment, the injector 27 ′ is provided with the heater H partially on the injection port 27c ′ side of the resin reservoir portion between the injection port 27c ′ and the screw cylinder 27b. It is good also as a structure which controls the temperature of molten resin by arrange | positioning to the whole. Further, not only the injector 27 'but also the injector 27 is provided with a heater H so that the temperature of the molten resin injected from the injector 27' is between the temperature of the molten resin injected from the injector 27 '. It is good also as a structure which provides a difference.

<Third Embodiment>
In the first and second embodiments, the temperature of the molten resin is adjusted by the heater H provided in the injection machine 27 ′. However, in this embodiment, the temperature is adjusted by the temperature setting means provided in the main body portion 21a. The temperature of the molten resin after being injected into the parison P is adjusted by circulating the medium. The same reference numerals are given to the same configurations as the common overall configuration described above, and the description thereof is omitted.

  FIG. 10 is a diagram illustrating a configuration of an injection molding apparatus A-3 according to the third embodiment. In the main body 21 a of the mold 21, that is, in the main body 21 a in contact with the portion (part B) close to the stretched portion of the parison P, a cold / hot water flow path 21 a ′ is formed, and the cold / hot water supply device 30 is formed. Connected with. A hose is connected between the cold / hot water supply device 30 and the cold / hot water flow path 21a ', and a switching valve 33 for switching between the cold water and the hot water is disposed in the middle thereof. In other words, the cold / hot water channel 21a 'functions as a temperature setting unit by allowing the temperature-controlled medium to flow through the cold / hot water channel 21a'.

  FIG. 11 is an explanatory diagram showing operation procedures of the injection molding apparatus A-3 and the cold / hot water supply apparatus 30. Using the horizontal axis as the time axis, the upper and middle stages show the processing of each process, and the lower stage shows the supply state of cold / hot water to the cold / hot water flow path 21a 'corresponding to the process. First, as shown in FIGS. 2 and 3, the parison P is suspended in the molds 21 and 22. Near the end of the drooping of the parison P, the switching valve 33 switches from cold water to hot water. Thereafter, the molds 21 and 22 are closed, and a blow process into the parison P, a molten resin injection process into the parison P, and a core back process are performed. Here, in at least a part of the period after the core back and during the demolding, the switching valve 33 switches from hot water to cold water. In the present embodiment, the hot water is switched to the cold water simultaneously with the completion of the core back. Thereafter, through a cooling step for cooling the temperature of the molten resin in the cavity, the molds 21 and 22 are opened, and the resin molded product is taken out.

  According to this configuration, the mold temperature around the portion B can be increased as compared with other portions, and accordingly, the temperature of the molten resin in the portion B can be increased. Thereby, like the case where the heater 27 is provided in the injection machine 27 ′, foaming of the portion B can be promoted, and a decrease in followability of the parison P with respect to the inner walls of the molds 21 and 22 can be suppressed. . Further, since the hot water can be switched to the cold water at the time when the core back process is completed, the cooling time can be shortened.

  In this embodiment, when the core back is completed, the hot water is switched to the cold water.However, by switching from the hot water to the cold water between the end of the injection of the molten resin and the completion of the core back, The cooling time can be further shortened. This leads to a reduction in cycle time.

  Moreover, in this embodiment, although it was set as the method of switching cold water and warm water completely at once, it is good also as a method of switching cold water and warm water gradually. That is, switching between cold water and hot water can be arbitrarily set according to the heat transfer characteristics of the molten resin, the resin temperature, the mold temperature, and the like.

<Fourth Embodiment>
In the first embodiment, the temperature of the molten resin is adjusted by the heater H provided in the injection machine 27 ′. However, in this embodiment, two types of molten resin having different cooling rates exist in the injection machine 27. As a result, the temperature of the molten resin injected into the cavity C is adjusted. The same components as those described above are denoted by the same reference numerals and description thereof is omitted.

  FIG. 12 is a view showing a configuration of an injection molding apparatus A-4 according to the fourth embodiment, and FIG. 13 is a view showing temperature changes of polyethylene and polypropylene. In this embodiment, for example, polyethylene (material A) or polypropylene (material B) is used as the resin material. In the graph shown in FIG. 13, the horizontal axis represents time t and the vertical axis represents temperature T. Polyethylene solidifies at time t1 and temperature T1, whereas polypropylene solidifies at time t2 and temperature T2 (t1> t2, T1 <T2). That is, it can be said that polyethylene has a larger foaming action than polypropylene, because it takes a longer time to reach the solidification temperature (slower cooling rate).

  Here, returning to FIG. 12, polyethylene and polypropylene are introduced into the injection machine 27 first from the polyethylene with a time difference. Therefore, in the injection machine 27, a molten resin having a characteristic that the cooling rate is slower than that of other parts is arranged on the injection port 27c side.

  According to this configuration, since the molten resin having a low cooling rate is injected into the cavity C first, the molten resin having a low cooling rate can be disposed in the portion B. Thereby, since it becomes difficult to be cooled when the molten resin comes into contact with the mold, it is possible to promote foaming of a portion (part B) adjacent to the stretched portion of the parison P, and the mold 21 of the parison P, It is possible to suppress a decrease in followability of the inner wall 22.

It is a schematic block diagram of the injection molding apparatus A which concerns on one Embodiment of this invention. It is a figure which shows the shaping | molding procedure of the resin molded product by the injection molding apparatus A, (a) is a figure which shows the drooping state of the parison P between the metal mold | die 21 and 22, (b) is a figure of the compressed gas in the parison P It is a figure which shows the blowing state. It is a figure which shows the shaping | molding procedure of the resin molded product by the injection molding apparatus A, (a) is a figure which shows a mode that a parison P is torn and perforated by injection | pouring of molten resin R, (b) is molten resin The figure which shows the state by which filling in the parison P of R was completed, (c) is a figure which shows a mode that molten resin foams by the core back of the metal mold | die 21b. It is explanatory drawing which shows the example using the punching apparatus 30, (a) is a figure which shows the state of the punching apparatus 30 at the time of the parison P drooping between the metal molds 21 and 22, (b) is the compression in the parison P The figure which shows the state of the perforation apparatus 30 at the time of gas blowing, (c) is a figure which shows the state of the perforation apparatus 30 at the time of injection | pouring of the molten resin in the parison P. It is explanatory drawing which shows the example using the punching apparatus 40, (a) is a figure which shows the state of the punching apparatus 40 at the time of dripping of the parison P between the metal mold | die 21 and 22, (b) is a compression in the parison P The figure which shows the state of the perforation apparatus 40 at the time of gas blowing, (c) is a figure which shows the state of the perforation apparatus 40 at the time of injection | pouring of the molten resin in the parison P. It is explanatory drawing which shows the example using the punching apparatus 40, (a) is a principal part enlarged view which shows the state of the punching apparatus 40 at the time of the blowing of the compressed gas in the parison P, (b) is a parison by the punching apparatus 40. It is a principal part enlarged view which shows a mode that P is drilled. It is a figure which shows the modification of the example using the punching apparatus 40, (a) is a principal part enlarged view which shows the state of the punching apparatus 40 at the time of blowing in the compressed gas in the parison P, (b) is the punching apparatus 40. FIG. 6C is a main part enlarged view showing a state in which the parison P is perforated, and FIG. 9C is a main part enlarged view showing a modification of the shutter member 41 ″. It is a figure which shows the structure of injection molding apparatus A-1 which concerns on 1st Embodiment. It is a figure which shows the structure of the injection molding apparatus A-2 which concerns on 2nd Embodiment. It is a figure which shows the structure of the injection molding apparatus A-3 which concerns on 3rd Embodiment. It is explanatory drawing which shows the operation | movement procedure of the injection molding apparatus A-3 and the cold / hot water supply apparatus 30. FIG. It is a figure which shows the structure of the injection molding apparatus A-4 which concerns on 4th Embodiment. It is a figure which shows the temperature change of a polypropylene and polyethylene.

Explanation of symbols

A Injection molding apparatus C Cavity H Heater P Parison 10 Extruder 20 Molding machines 21 and 22 Molds 23 and 24 Hydraulic actuator 27 Injection machine 28 Foaming agent supply device

Claims (16)

A step of clamping the mold so that the extruded non-foaming and stretchable cylindrical molded body is placed in the cavity of the mold; and
An injection step of injecting a foamable molten resin into the blow molded body in the cavity in a state where the tubular molded body is expanded in the cavity to form a blow molded body;
A foaming step of foaming the molten resin inside the blow molded body while increasing the volume of the cavity by core-backing the mold;
Have
In the foaming step, another part is filled with the temperature of the molten resin filled in a part close to the stretched part of the blow molded body that is stretched as the volume of the cavity is increased by the core back. A method for molding a resin molded product, wherein the temperature is set higher than the temperature of the molten resin.   In the injection step, the temperature of the molten resin existing in the injection machine is set to be higher on the injection port side than other parts by a heater provided in the injection machine for injecting the molten resin. The method for molding a resin molded product according to claim 1.   In the injection step, the molten resin having a different cooling rate is present in an injection machine for injecting the molten resin, and the molten resin present on the injection port side has a characteristic that the cooling rate is slower than other portions. The method for molding a resin molded product according to claim 1 or 2.   There is provided temperature setting means for controlling the temperature of a portion of the mold adjacent to the stretched portion of the blow molded body, and the mold is set by the temperature setting means during at least a part of the period after the core back and during demolding. The method for molding a resin molded product according to any one of claims 1 to 3, wherein a temperature of a portion adjacent to the stretched portion of the blow molded article is set lower than that of other portions.   5. The temperature setting means sets the temperature by circulating a temperature-adjusted medium through a flow path formed in a portion of the mold close to the stretched portion of the blow molded body. The molding method of the resin molded product of description.   The method for molding a resin molded product according to any one of claims 1 to 5, wherein the foamable molten resin contains reinforcing fibers.   The method for molding a resin molded product according to any one of claims 1 to 6, wherein the foamable molten resin contains a physical foaming agent.   The method for molding a resin molded product according to claim 7, wherein the physical foaming agent is a fluid in a supercritical state. A mold moving mechanism that performs a core back operation for clamping and opening the mold and increasing the volume of the cavity, and
An extrusion molding machine for extruding a non-foaming and stretchable cylindrical molded body;
An injection machine that injects a foamable molten resin into the blow molded body in the cavity in a state where the cylindrical molded body is expanded in a mold-clamped cavity to form a blow molded body,
At the time of foaming of the molten resin, the temperature of the molten resin filled in a portion close to the stretched portion of the blow molded body that is stretched as the volume of the cavity is increased by the core back is filled in another portion. Temperature setting means for setting the temperature higher than the temperature of the molten resin,
An apparatus for molding a resin molded product, comprising:   The temperature setting means sets the temperature of the molten resin existing in the injection machine by a heater provided in the injection machine so that the injection port side is higher than other parts. The molding apparatus of the resin molded product of Claim 9.   The temperature setting means is set so that the molten resin having a characteristic that a cooling rate is slower than other parts is arranged on an injection port side of the injection machine. The molding apparatus of the resin molded product of description.   The temperature setting means has means for circulating a temperature-controlled medium in a flow path formed in a portion of the mold close to the stretched portion of the blow molded article, and after the core back and during the demolding In at least a part of the period, the temperature-adjusted medium is circulated through the flow path to set the temperature of the part close to the stretched part of the blow molded body in the mold lower than the other parts. The apparatus for molding a resin molded product according to any one of claims 9 to 11.   The mold is disposed on the outer periphery of the first mold, a second mold that moves relative to the first mold and that forms a cavity with the first mold when the mold is clamped. A third mold that abuts the first mold and the second mold during mold clamping and forms a part of the cavity while being separated from the second mold in accordance with the core back operation of the second mold. The apparatus for molding a resin molded product according to claim 12, wherein the flow path is formed in the third mold.   The apparatus for molding a resin molded product according to any one of claims 9 to 13, wherein the injection machine injects the molten resin containing reinforcing fibers.   The apparatus for molding a resin molded product according to claim 9, wherein the injection machine injects the molten resin containing a physical foaming agent.   The said injection machine inject | pours the said molten resin containing the fluid of a supercritical state as a physical foaming agent, The molding apparatus of the resin molded product of Claim 15 characterized by the above-mentioned.