JP2008246697A - Method and apparatus for molding resin molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding method of a resin molded product capable of suppressing the obstruction of expansion of a blow molded object, and a molding apparatus of the resin molded product. <P>SOLUTION: After a foamable resin 31 is injected in the hollow blow-molded object 23 formed by the blow molding of a parison, the core part of a mold 10 is moved by predetermined quantity in a mold opening direction so as to magnify the volume of the cavity of the mold and the foaming of the foamable resin is accelerated to expand the blow-molded object 23 to mold the resin molded product. Before or after the start of the movement of the core part 13, a separation part 23b is formed to the part 23a to be stretched accompanied by the expansion of the blow-molded object 23 of the blow-molded object 23. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

For example, in various industrial parts such as automobile parts, foamed resin molded articles having excellent characteristics such as lightness and heat insulation are widely used. As this foamed resin molded product, for example, Patent Document 1 intends to obtain a foamed product with a skin having excellent lightness and rigidity, and is a hollow molded product obtained by blow molding a parison having a thermoplastic resin foamed layer. A foamed molded article with a skin is disclosed in which a foamed thermoplastic resin piece is filled in and the foam piece is heated to fuse the foam pieces together.
JP 2004-284149 A

  By the way, as a method for molding a resin molded product made of a foamable resin containing a foaming agent in a resin, after injecting a foamable resin smaller than the volume of the mold cavity into the cavity, the foamable resin is injected into the cavity. After the foaming resin is injected into the cavity of a pair of molds consisting of a fixed mold and a movable mold, the movable mold is moved in the mold opening direction. There is known a molding method (so-called core back method) that promotes foaming of a foamable resin by enlarging the volume of the cavity. For example, when obtaining a large resin molded product or a resin molded product with a high expansion ratio For this, the core back method is preferably used.

  In this way, after injecting the foamable resin into the cavity of the mold composed of the fixed mold and the movable mold, the movable mold is moved in the mold opening direction to expand the volume of the cavity to promote foaming of the foamable resin. In the formed resin molded product, bubbles formed by foaming of the foamable resin may break up in the skin layer which is the outermost surface of the molded product, which may cause problems such as poor appearance.

  On the other hand, as a means for improving the surface properties of a resin molded product made of a foamable resin, after a parison made of a molten resin is suspended in a mold, the parison is sandwiched between molds and a gas such as air is introduced. There is known a molding method of a resin molded product in which hollow molding (so-called blow molding) and foam molding combined with blow molding are combined.

  However, in the molding of a resin molded product in which a foamable resin is injected into a blow molded body formed by blow molding a parison and foaming of the foamable resin is promoted by the core back method, the cavity of the mold When the core part of the mold is moved so as to increase the volume of the mold, the foamed resin is promoted to expand and the blow molded body is expanded, the stretched part of the blow molded body is cooled by the mold and hardly stretched. Thus, expansion of the blow molded product may be hindered. In such a case, for example, in the corner portion of the blow molded body located at the peripheral portion of the cavity facing surface of the core portion, the resin molded product is not molded by following the movement of the core portion, and problems such as poor appearance Can cause.

  Accordingly, the present invention has been made in view of the above technical problem, and can promote the foaming of the foamable resin to expand the blow molded body, and the blow molded body is accompanied with the expansion of the blow molded body. An object of the present invention is to provide a molding method and a molding apparatus for a resin molded product that can prevent the expansion of the foamable resin in the blow molded body from being cooled by the molding die.

For this reason, in the molding method of the resin molded product according to claim 1 of the present application, the parison made of solid resin is extruded into a mold that is opened, the mold is closed with the parison interposed therebetween, and then the parison is blown. Molding to form a hollow blow molded body, injecting a foamable resin into the blow molded body after forming the blow molded body, and expanding the volume of the cavity in the mold after the start of the injection of the foamable resin A method for molding a resin molded product, wherein the core part of the molding die is moved by a predetermined amount so as to promote foaming of the foamable resin and expand the blow molded body,
Before or after the start of the movement of the core part, a separation part is formed in a portion where the blow molded body is stretched as the blow molded body expands.

  The invention according to claim 2 of the present application is the invention according to claim 1, wherein the separation part is formed in the blow molded body after the formation of the blow molded body and before the movement of the core portion is started. It is characterized by.

  Further, the invention according to claim 3 of the present application is the invention according to claim 1 or 2, further comprising a fixed mold and a movable mold that form a cavity in the mold, and any one of the fixed mold and the movable mold. When one of the molds closes the other mold of the fixed mold and the movable mold when the mold is closed, at least one of the fixed mold and the movable mold is positioned on the outer periphery of the core portion. Using the mold having the outer peripheral portion and the core portion movable relative to the outer peripheral portion so as to enlarge the volume of the cavity of the mold, and the separation portion is a cavity facing surface of the core portion And in the vicinity of the adjacent portion between the outer peripheral portion and the inner surface of the outer peripheral portion.

  Still further, the invention according to claim 4 of the present application is characterized in that, in the invention according to claim 3, the separation portion is formed in a substantially square shape as a whole with respect to the blow molded article. is there.

  Furthermore, the invention according to claim 5 of the present application is characterized in that, in the invention according to any one of claims 1 to 4, the foamable resin contains a reinforcing fiber that reinforces the foamable resin. To do.

  The invention according to claim 6 of the present application is characterized in that, in the invention according to any one of claims 1 to 5, the foamable resin contains a physical foaming agent.

  Furthermore, the invention according to claim 7 of the present application is characterized in that, in the invention according to claim 6, the physical foaming agent is a fluid in a supercritical state.

A molding apparatus for a resin molded product according to claim 8 of the present application includes: a mold that can be opened and closed; an extrusion head that extrudes a parison made of a solid resin into the mold that is opened; and the mold that sandwiches the parison. A pressurized fluid supply means for supplying a pressurized fluid into the parison after the mold has been closed to form a hollow blow-molded body, an injection means for injecting a foamable resin into the blow-molded body, Core moving means for moving the core portion of the mold so as to expand the volume of the cavity, and after the start of the injection of the foamable resin into the blow molded body, the volume of the cavity of the mold is expanded. A molding apparatus for a resin molded product that moves the core part to expand the blow molded body by promoting foaming of the foamable resin,
It further comprises an incision means for forming a separating portion in a portion where the blow molded body is stretched with the expansion of the blow molded body before or after the start of movement of the core portion. To do.

  The invention according to claim 9 of the present application is the invention according to claim 8, wherein the separating part is formed by the cutting means after the formation of the blow molded body and before the start of the movement of the core part. It is characterized by.

  Furthermore, the invention according to claim 10 of the present application is the invention according to claim 8 or 9, wherein the mold has a fixed mold and a movable mold, and one of the fixed mold and the movable mold. Is closed with the other mold of the fixed mold and the movable mold when the mold is closed, and at least one of the fixed mold and the movable mold is positioned on the outer periphery of the core portion; The core portion movable relative to the outer peripheral portion so as to increase the volume of the cavity of the mold, and the cutting means is in the vicinity of the adjacent portion between the cavity facing surface of the core portion and the inner surface of the outer peripheral portion Is provided.

  Still further, the invention according to claim 11 of the present application is the invention according to claim 10, wherein the cutting means forms the separating portion in a generally rectangular shape as a whole with respect to the blow molded body. It is characterized by being.

  Furthermore, the invention according to claim 12 of the present application is characterized in that, in the invention according to any one of claims 8 to 11, the injection means injects a foamable resin containing a physical foaming agent. It is.

  The invention according to claim 13 of the present application is the invention according to claim 12, wherein the injection means injects a foamable resin containing a fluid in a supercritical state as the physical foaming agent. Is.

  According to the molding method of the resin molded product according to claim 1 of the present application, the blow molding cooled by forming the separation portion in the portion where the blow molded body is stretched as the blow molded body expands. Stretching the stretched part of the body can prevent the expansion of the expandable resin, and as a result, the expansion of the expandable resin is promoted to the corner of the cavity in the mold, and the shape of the cavity is accurately handled. The molded resin product can be easily and reliably molded.

  Further, according to the invention according to claim 2 of the present application, the blow molding is inhibited by forming the separating portion in the blow molded body after the formation of the blow molded body and before the start of the movement of the core portion. The above effects can be obtained with certainty.

  Further, according to the invention method of claim 3 of the present application, at least one of the fixed mold and the movable mold uses a mold having an outer peripheral part and a core part, and the separating part has a cavity facing surface and an outer peripheral part of the core part. By forming near the inner surface of the portion, the above-described effect can be obtained with a relatively simple structure without complicating the structure of the mold and its driving mechanism.

  Still further, according to the invention according to claim 4 of the present application, the separation part is formed in a generally square shape as a whole with respect to the blow molding, so that the blow molded body is surrounded by the separation part substantially entirely. Can be easily separated from other parts, and the above-mentioned effect can be obtained with certainty.

  Furthermore, according to the invention of claim 5 of the present application, it is possible to further promote foaming of the foamable resin by the springback phenomenon of the reinforcing fibers contained in the foamable resin.

  Furthermore, according to the invention according to claim 6 of the present application, since the physical foaming agent is contained in the foamable resin, a resin molded product having a fine foam cell diameter can be molded. The physical properties such as bending rigidity can be further improved.

  Furthermore, according to the invention according to claim 7 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, and the above-described effect can be obtained. Furthermore, it can play effectively.

  According to the molding apparatus for a resin molded product according to claim 8 of the present application, by including an incision means for forming a separation portion in a portion where the blow molded body is stretched as the blow molded body is expanded. The expansion of the foamed resin can be prevented from being hindered by stretching the stretched part of the cooled blow molded product, and as a result, the expansion of the foamable resin is promoted to every corner in the mold, and the cavity shape It is possible to easily and reliably mold a resin molded product corresponding to the above.

  Further, according to the invention according to claim 9 of the present application, the blow molding is inhibited by forming the separating portion in the blow molded body by the cutting means after the formation of the blow molded body and before the start of the movement of the core portion. The above-mentioned effect can be obtained without fail.

  Still further, according to the invention of claim 10 of the present application, at least one of the fixed mold and the movable mold uses a mold having an outer peripheral part and a core part, and the separating part has a cavity facing surface and an outer periphery of the core part. By providing the incision means so as to be formed near the inner surface of the portion, the above-described effect can be obtained with a relatively simple structure without complicating the structure of the mold and its driving mechanism. .

  Still further, according to the invention of claim 11 of the present application, the separation part is formed in a substantially square shape as a whole with respect to the blow molded body by the incision means, so that the separation part surrounds substantially the entire circumference. A part of the blow molded body can be easily separated from other parts, and the above-mentioned effect can be obtained with certainty.

  Furthermore, according to the invention according to claim 12 of the present application, the injection means can inject a foamable resin containing a physical foaming agent to form a resin molded product having a fine foam cell diameter. In the molded product, physical properties such as bending rigidity can be further improved.

  Furthermore, according to the invention according to claim 13 of the present application, the injection means injects a foamable resin containing a fluid in a supercritical state as a physical foaming agent, whereby a resin molded product having finer foam cells is obtained. It can shape | mold and can show | play the said effect more effectively.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a schematic explanatory view showing a molding apparatus 1 for a resin molded product according to the first embodiment of the present invention. As shown in the figure, the molding apparatus 1 includes a molding die 10 that can be opened and closed, an extrusion head 21 that extrudes a heated and melted first resin as a parison 20, and supplies pressurized fluid into the molding die 10. And a blow pin 25 as a pressurized fluid supply means.

  The mold 10 is composed of a fixed mold 11 and a movable mold 12, and by closing the fixed mold 11 and the movable mold 12, a cavity 16 corresponding to the desired shape of the resin molded product is formed in the mold 10. Is done. The movable mold 12 includes a core portion 13 that defines a part of the cavity 16 and an outer peripheral portion 14 that is combined with the core portion 13.

  The blow pin 25 supplies pressurized gas, such as compressed air, as pressurized fluid supplied from a pressurized fluid supply source (not shown) to the molding die 10 to keep the molding die 10 at a predetermined pressure. Be able to. Further, the blow pin 25 can exhaust air in the mold 10 in a state where the blow pin 25 is inserted into the mold 10. The fixed die 11 of the molding die 10 is provided with an insertion hole 26 through which the blow pin 25 is inserted, and the blow pin 25 is configured to be movable forward and backward within the insertion hole 26.

  FIG. 2 is a perspective view showing the movable mold 12 of the mold 10. In FIG. 2, the core section 13 is moved in the mold opening direction with respect to the outer peripheral section 14. As shown in FIG. 2, the core portion 13 of the movable mold 12 includes a protruding portion 13 b that protrudes in a square shape from a plate-shaped portion 13 a that is formed in a substantially flat plate shape, and is perpendicular to the mold opening / closing direction of the mold 10. The outer peripheral portion 14 formed in a square frame shape according to the outer peripheral shape of the protruding portion 13b is fitted on the outer periphery of the protruding portion 13b in any direction.

  The movable mold 12 is configured such that the core portion 13 and the outer peripheral portion 14 can be integrally moved in the mold opening / closing direction with respect to the fixed mold 11, and the movable mold 12 is movable after the fixed mold 11 and the movable mold 12 are closed. In a state where the outer peripheral portion 14 of the mold 12 and the fixed mold 11 are closed, the volume of the cavity 16 of the mold 10 is expanded by a core moving mechanism (not shown) that moves only the core 13 in the mold opening / closing direction. Thus, only the core part 13 of the movable mold 12 is configured to be movable in the mold opening direction.

  In the present embodiment, the movable mold is composed of the outer peripheral portion and the core portion. Alternatively, the fixed mold may be composed of the outer peripheral portion and the core portion, or the fixed mold and the movable mold are movable. Both of the molds may be composed of an outer peripheral portion and a core portion, respectively.

  Referring to FIGS. 1 to 3, a cutting blade 40-43 as an incision means can be moved forward and backward relative to the cavity 16 in the mold 10 by a cutting blade drive mechanism (not shown) on the outer peripheral portion 14 of the movable mold 12. Is provided. As shown in FIG. 2, slits 14 b and 14 b (only the upper part is shown) are formed on the upper and lower parts of the outer peripheral part 14, and slits 14 c and 14 c (only one is shown) are formed on both sides. . In these 14b and 14c, as shown in FIG. 3 (a), four rectangular cutting blades 40, 41, 42 and 43 are mounted, respectively, and each cutting blade 40-43 is not in operation. The front edge portion is substantially flush with the inner surface of the outer peripheral portion 14.

  Here, each of the cutting blades is not limited to a plate-like one, and any form may be used as long as it has a function of forming a separating portion in a blow molded body as will be described later. Perforations may be formed by arranging needle pins and puncturing the blow molded body. Moreover, if each said cutting blade is heated more than the melting temperature of 1st resin which comprises the parison 20, the cut formation to the blow molding body mentioned later can be performed more reliably.

  FIG. 3A shows a state where the four cutting blades 40-43 are operated and protrude into the cavity 16 of the mold 10. In this case, the edge portions of the respective cutting blades 40-43 are separated from each other, and when the cut (separation portion) is made from the upper, lower, left, and right sides with respect to the blow molded body in the cutting operation described later, the cuts extend over the entire circumference. Although not cut, the uncut portions remain in the four corner portions, but when viewed as a whole, a substantially square cut is formed. On the other hand, as shown in FIG. 3B, when the four cutting blades 40-43 protrude into the cavity 16 of the mold 10, the edge portions of the cutting blades 40-43 are in contact with each other. In this case, since the cuts by the respective cutting blades 40-43 are continuous, a complete B-shaped cut is formed as a whole with respect to the blow molded body.

  Note that the number of cutting blades is not necessarily four. For example, as shown in FIG. 3C, only two cutting blades 40 and 41 may be used in the vertical direction, or two in the left-right direction. Only one cutting blade 42, 43 may be used, or it is conceivable to provide only one cutting blade.

  As shown in FIG. 4, the molding apparatus 1 further includes an injection apparatus 30 as injection means for injecting a foamable resin containing a foaming agent into the second resin into the mold 10. The injection device 30 is for injecting a foamable resin 31 into the mold 10 and has a cylinder 33 for kneading and melting the second resin 32. A screw 34 is provided inside the cylinder 33, and a screw drive mechanism and an injection mechanism (both not shown) are connected to the rear end of the screw 34.

  In the injection apparatus 30, the second resin 32 put into the cylinder 33 is sequentially heated and kneaded and melted by a heater (not shown) and a screw 34 provided around the cylinder 33. Then, for the second resin 32 kneaded and melted, the inert gas brought into a supercritical state from a cylinder 35 containing an inert gas such as carbon dioxide or nitrogen via a supercritical fluid generator 36, It is injected by a supercritical fluid injection device 37. Thereby, the expandable resin 31 which made the 2nd resin 32 contain the foaming agent is produced.

  The foamable resin 31 is injected into the mold 10 by the screw 34 being rotated by the screw drive mechanism and being injected by the injection mechanism. The mold 10, specifically the fixed mold 11, is provided with an injection path 17 that communicates with the nozzle 38 of the injection device 30 and injects the foamable resin 31 into the mold 10.

  The molding apparatus 1 includes a control unit (not shown) that comprehensively controls the molding apparatus 1, and the control unit drives the opening / closing of the molding die 10 and the mold of the core portion 13 of the molding die 10. It controls the movement mechanism in the opening direction, the parison extrusion mechanism of the extrusion head 21, the operation mechanism of the blow pin 25, the pressurized fluid supply mechanism from the blow pin 25, and the operation of the injection mechanism of the foamable resin 31 of the injection device 30. .

  Further, the control unit is provided with a timer (not shown), and the control unit performs various controls according to the time from when the parison 20 is suspended. 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 will be described.
First, as shown in FIG. 1, in a state where the mold 10 is opened, from the extrusion head 21 into the mold 10, specifically, the cavity facing surface 11 a of the fixed mold 11 and the core portion 13 of the movable mold 12. The parison 20 made of the first resin heated and melted between the cavity facing surface 13c is extruded into a cylindrical shape. As the first resin, for example, a non-foamed solid resin such as a thermoplastic resin can be used.

  Then, the core portion 13 and the outer peripheral portion 14 of the movable die 12 are integrally moved in the die closing direction with respect to the stationary die 11 to close the molding die 10, and the upper end side and the lower end side of the parison 20 are fixed to the stationary die 11. And the outer peripheral portion 14 of the movable mold 12. As a result, the space inside the parison 20 is closed, and the space 22 is formed inside the parison 20. Thereafter, pressurized gas is supplied into the space 22 of the parison 20.

  FIG. 5 is a schematic explanatory view showing a state where pressurized gas is supplied to the parison located in the mold of the molding apparatus. The blow pin 25 is advanced, pressurized gas is supplied to the space 22 inside the parison 20 by the blow pin 25, and the parison 20 is blow-molded. Thereby, the internal space of the parison 20 expands and is pressed against the cavity facing surfaces 11a and 13c, and a hollow blow molded body 23 corresponding to the cavity facing surfaces 11a and 13c is formed.

  FIG. 6 is a schematic explanatory view showing a state in which a foamable resin is injected into the mold 10. When the parison 20 extruded into the molding die 10 is blow-molded, next, the supercritical fluid is contained in the space 22 in the blow-molded body 23 from the injection device 30 to the second resin 32. A foamable resin 31 is injected. As the second resin, for example, a thermoplastic resin such as polypropylene can be used.

  Further, after the molding of the blow molded body 23 is completed, each cutting blade 40-43 is driven and each leading edge portion protrudes into the cavity in the molding die 10. As a result, as shown in FIG. 7, the cavity facing surface 13 c of the core portion 13 and the inner surface of the outer peripheral portion 14 with respect to the portion 23 a of the blow molded body 23 that is in pressure contact with the outer peripheral portion 14 of the movable mold 12. In the vicinity of the portion adjacent to 14a, a substantially square-shaped cut is formed as a whole. This break becomes the separation portion 23b when the core portion 13 starts moving to promote foaming of the foamable resin 31 described later (see FIGS. 11 and 12). Here, the portion 23a in pressure contact with the inner surface 14a of the outer peripheral portion 14 in the blow molded body 23 is a portion that is stretched along with the expansion of the foamable resin 31 during the core back unless the cut is formed. It corresponds to.

  The reason why the cuts are formed in the blow molded body 23 by the cutting blades 40-43 as described above is after the blow molded body 23 is formed, because the blow molding of the parison 20 is not hindered. In addition, the timing for forming the cut is preferably after the formation of the blow molded body 23 and before the start of the movement of the core 13 described later, but the injection of the foamable resin 31 into the blow molded body 23 is completed. It may be after the start of the movement of the core unit 13 executed later.

Next, an injection mechanism of the foamable resin 31 from the injection device 30 to the space 22 in the blow molded body 23 will be described with reference to FIGS.
FIGS. 8 to 10 sequentially show the steps in which the foamable resin 31 is injected from the injection device 30 into the space 22 in the blow molded body 23, and an enlarged view of a portion A 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 17 provided in the fixed mold 11 communicates with a recess 11b formed in the cavity facing surface 11a, and a first valve body 51 is provided on the bottom side of the recess 11b. . The first valve body 51 is connected to a drive cylinder 53 via a rod 52 and is configured to be movable in the vertical direction by operating the drive cylinder 53. The injection path 17 is closed by moving the first valve body 51 upward. Further, the injection path 17 is provided with a second valve body 54 configured to open and close the injection path 17 and move in the horizontal direction. Thereby, in the injection | pouring path | route 17, the foamable resin 31 can be inject | poured in the shaping | molding die 10 in the state which the 1st valve body 51 and the 2nd valve body 54 opened.

  As shown in FIG. 8, with the first valve body 51 and the second valve body 54 closing the injection path 17, pressurized gas is supplied to the space 22 in the parison 20, and the parison 20 is cavityd. When pressed against the opposing surface 11a, the parison 20 is also pressed against the surface of the recess 11b in a U-shaped cross section, but the thickness of the parison 20 is formed thin at this portion.

  And as shown in FIG. 9, after operating the drive cylinder 53 and moving the 1st valve body 51 below, pressurized gas is supplied through the blow pin 25 and the pressure of the space part 22 is raised. Then, the parison 20 having a U-shaped cross section in the recess 11b is opened at the bottom 20a.

  Subsequently, after the second valve body 54 is moved so as to open the injection path 17 and the space portion 22 and the injection path 17 are communicated with each other, as shown in FIG. Is injected into the space 22. 8 to 10 show an example of the injection of the foamable resin into the hollow blow-molded body 23 formed by blow-molding the parison 20, and foaming is performed by other suitable means. The functional resin 31 may be injected.

  In this way, when the foamable resin 31 is injected into the blow molded body 23, the air in the space 22 of the blow molded body 23 is discharged through the blow pins 25 as the foamable resin 31 is injected. The When the foamable resin 31 is filled into the blow molded body 23, the blow pin 25 is retracted, and then the cavity of the mold 10 is closed with the fixed mold 11 and the outer peripheral portion 14 of the movable mold 12 closed. Only the core portion 13 of the mold 10 is moved in the mold opening direction so as to increase the volume of 16. Thereby, foaming of the foamable resin 31 is promoted, and the blow molded body 23 is expanded.

  FIG. 11 is a schematic 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, after the foamable resin 31 is injected into the blow molded body 23, the core portion 13 of the mold 10 is expanded so as to increase the volume of the cavity 16 of the mold 10. A predetermined amount is moved in the mold opening direction, that is, in the direction of the arrow X1. Thereby, foaming of the foamable resin 31 is promoted, and the blow molded body 23 expands. Then, the foamable resin 31 in a molten state is cooled and solidified, and a resin molded product 24 in which the foamable resin 31 is injected and foamed into the blow molded body 23 is molded. In addition, the movement of the core part 13 may be started before the injection of the foamable resin 31 into the blow molded body 23 is completed.

  Thus, after injecting the foamable resin 31 into the blow molded body 23, the core portion 13 of the molding die 10 is moved in the mold opening direction so as to expand the volume of the cavity 16 of the molding die 10, and resin molding is performed. When the product 24 is molded, the blow molded body 23 is cooled by the cavity facing surface 13c of the core portion 13 of the mold 10 and the inner surface 14a of the outer peripheral portion 14, and the blow molded body is moved when the core portion 13 is moved in the mold opening direction. 23 part 23a is not stretched in the mold opening direction and the blow molded body 23 is prevented from expanding, which may cause problems such as poor appearance such as sagging of the corner portion. In this embodiment, the blow molded body Such a problem can be avoided by providing the separation portion 23b in 23.

  FIG. 11 is an explanatory cross-sectional view showing an enlarged portion B of FIG. As described above, when the core portion 13 of the mold 10 is moved in the mold opening direction so as to increase the volume of the cavity 16 of the mold 10, the blow molded body 23 expands in the mold opening direction. Since the molded body 23 is formed with a substantially square-shaped separation portion 23b around the four sides, the expansion of the foamable resin 31 is prevented by stretching the portion 23a of the blow molded body 23 that is in contact with the inner surface of the outer peripheral portion 14. Can be prevented.

  Thus, according to the shaping | molding apparatus 1 and this shaping | molding method of this embodiment, by forming the isolation | separation part 23b in the part 23a to which the blow molding 23 is extended with expansion | swelling of the blow molding 23 The expansion of the foamable resin 31 can be prevented by the stretched portion 23a of the cooled blow molded body 23 being stretched, and as a result, the foamable resin 31 reaches the corner of the cavity 16 in the mold 10. The resin molded product 24 corresponding to the cavity shape can be molded easily and reliably. Further, in the completed resin molded product 24, the surface of the foamable resin 31 is exposed at the separation portion 23. However, the resin molded product 24 is the object (for example, in a state where the exposed portion is not visible to the human eye). If it is designed so that it can be assembled to a car body, etc., there will be no appearance problems.

  Further, by forming a cut to be the separation portion 23b in the blow molded body 23 after the formation of the blow molded body 23 and before the start of the movement of the core portion 13, the blow molded body 23 is prevented from being obstructed by blow molding. Cuts can be formed.

  Furthermore, the molding die 10 having the movable die 12 having the core portion 13 and the outer peripheral portion 14 is used to move the core portion 13 to expand the blow molded body 23. However, the mold forming cavity is fixed. When the mold is closed, the mold is closed with the movable mold, and the mold can be moved relative to the outer periphery to increase the volume of the mold cavity and the outer periphery of the mold core. Alternatively, a blow mold may be expanded by using a molding die provided with a core portion and moving the core portion of the fixed die in the mold opening direction. Even in such a case, the same effect as that of the above embodiment can be obtained by forming the separation portion in the portion where the blow molded body is stretched when the blow molded body is expanded.

  Furthermore, the separation part 23b is formed in a substantially square shape as a whole with respect to the blow molded body 23, so that a part of the blow molded body 23 that is surrounded by the separation part 23 substantially from the entire circumference is separated from other parts. They can be easily separated, and the above effects can be obtained more reliably.

  Furthermore, since the foaming resin 31 contains a physical foaming agent, it is possible to mold a resin molded product having a fine foam cell diameter, and to further improve physical properties such as bending rigidity in the resin molded product. Can do.

  Still further, by containing the reinforcing fiber in the foamable resin 31, it is possible to further promote foaming of the foamable resin by the springback phenomenon of the fiber. Even when molding using a foamable resin containing reinforcing fibers, a resin molded product with good surface properties can be obtained without the reinforcing fibers being exposed to the surface of the resin molded product and deteriorating the surface appearance. Can do.

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

  In the molding apparatus 1 according to the first embodiment, when the foamable resin 31 is injected into the space portion 22 of the parison 20, the air in the space portion 22 is discharged through the blow pin 25. A gas discharge hole for discharging the gas in the space 22 may be provided in the parison 20 that defines the above.

  By the way, in the shaping | molding apparatus 1 of the said 1st Embodiment, the cutting blades 40-43 were provided in the outer peripheral part 14 of the movable mold | type 12, and were advanced / retracted driven in the direction orthogonal to the moving direction of the core part 13. FIG. However, as shown in FIG. 13, the cutting blade 44 may be provided in the core portion 13 of the movable mold 12 and driven forward and backward with respect to the cavity 16 in parallel with the moving direction of the core portion 13. In this case, the cutting blade 44 is configured to have a substantially square shape when viewed from the cavity 16 side. Thereby, the separation part 23b formed in the surface which contacts the cavity opposing surface 13c of the core part 13 in the blow molding 23 is also as shown in FIG. 14 between the cavity opposing surface 13c and the inner surface 14a of the outer peripheral part 14. In the vicinity of the adjacent portion, the core portion is formed in a substantially square shape. The portion of the blow molded body 23 that contacts the cavity facing surface 13c of the core portion 13 in the vicinity of the adjacent portion is also stretched as the blow molded body 23 expands due to foaming of the internal foamable resin 31. It corresponds to. Also by this modification, the same effect as the molding apparatus 1 of the first embodiment can be obtained.

  Next, a molding apparatus for a resin molded product according to the second embodiment of the present invention will be described with reference to FIGS. 15 to 17. The molding apparatus of the present embodiment is the molding apparatus 1 of the first embodiment. In contrast, the cutting blade 40-43 which is an incision means for forming the separation part is not provided, and the configuration of the extrusion head 21 for extruding the parison 20 into the mold 10 which is opened is different. The only difference is that Therefore, in this embodiment, only the description of the difference will be given, and the description of the first embodiment will be omitted for the same configuration as that of the molding apparatus 1 here.

  In the molding apparatus of this embodiment, as shown in FIG. 15, a cylindrical parison 20 in which the first molten resin is extruded from the extrusion head 21 extends annularly in the circumferential direction and is predetermined in the cylindrical axis direction. Two horizontally thin portions 20a, 20a provided at intervals, and two strip-like vertical thin portions 20b, 20b extending in the cylindrical axis direction and provided at predetermined intervals in the circumferential direction, It is formed including. A rectangular region, which is partitioned in a generally square shape around the four sides by the horizontal thin portion 20a and the vertical thin portion 20b, is formed by the core portion 13 of the movable die 12 when blow-molded in the mold 10 that is closed. A part of the blow molded body 23 that comes into contact with the cavity facing surface 13c is configured, and the horizontal thin portion 20a and the vertical thin portion 20b correspond to the separation portion 23b in the first embodiment.

  Since the horizontal thin portion 20a and the vertical thin portion 20b formed in this way are formed thinner than the other portions, the foamable resin 31 is injected into the blow molded body 23 and the core portion 13 has a predetermined amount. When moving, the horizontal thin portion 20a and the vertical thin portion 20b are broken by the tension acting in the process in which the blow molded body 23 expands as the foamable resin 31 expands. As a result, as in the case of the first embodiment, it is possible to prevent the expansion of the foamable resin 31 from being hindered by the cooled blow molded body 23 being stretched. The expansion of the foamable resin 31 is promoted to the corner portion of the cavity 16, and the resin molded product 24 corresponding to the cavity shape can be easily and reliably molded.

  16 and 17 show the extrusion head 21 of the molding apparatus in the present embodiment. The extrusion head 21 has a substantially cylindrical die 45 that forms an extrusion passage 48 between a substantially frustoconical core 46 fixed to a drive rod 47 and an outer peripheral surface of the core 46 surrounding the core 46. And. The drive rod 47 is connected to a core drive mechanism (not shown) and can be driven up and down in the direction of the arrow.

  As shown in FIG. 17, two convex portions 46 a are projected from the outer peripheral surface of the core 46. The vertical thin portion 20b is formed by narrowing the width of the outlet 49 of the extrusion passage 48 by the convex portions 46a. On the other hand, the horizontal thin portion 20a is formed by narrowing the width of the outlet 49 of the extrusion passage 48 by the vertical movement of the core 46 in a short time by the core driving mechanism.

  In addition, the convex part 46a provided in the core 46 is not limited to what is comprised by three inclined surfaces as shown in figure, What kind of shape will be sufficient if it plays the role which narrows the exit width | variety of an extrusion channel | path? It may be. Moreover, you may project the above convex part on the inner surface of die | dye instead of a core.

  Next, a molding apparatus for a resin molded product according to a third embodiment of the present invention will be described. FIG. 18 is a schematic view showing a state in which pressurized gas is supplied to a parison located in a mold of the molding apparatus in the molding apparatus for a resin molded product according to the third embodiment of the present invention. 19 is a schematic perspective view showing a state in which a foamable resin is injected into a blow molded body in 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.

  As shown in FIG. 18, when the mold 60 is closed, the pin 61 is provided on the fixed mold 11 so as to protrude into the space formed by the cavity facing surfaces 11a and 13c. The pin 61 has a front end formed in a tapered shape and a rear end attached to the movable plate 62. The movable plate 62 is configured to allow the pin 61 to move forward and backward with respect to the space formed by the cavity facing surfaces 11a and 13c, for example, by a drive cylinder or the like.

  Further, in the mold 60, an exhaust path 64 for discharging gas in the space formed by the cavity facing surfaces 11 a and 13 c is formed in the fixed mold 11, and the exhaust path 64 advances the movable plate 62. It is closed by making it move, and it opens by moving the movable plate 62 backward.

  As described above, when the pressurized gas is supplied to the space portion 22 of the parison 20 and the parison 20 is pressed against the cavity facing surface 11a, the pin 61 is stuck in the parison 20 as shown in FIG. The parison 20 is pressed against the cavity facing surface 11 a, and a gas discharge hole 20 b is formed in the parison 20 by a pin 61.

  When the foamable resin 31 is injected into the space 22, as shown in FIG. 19, the blow pin 25 is moved backward and the movable plate 62 is moved backward. Thereby, the gas in the space 22 can be discharged from the gas discharge hole 20 b through the exhaust path 64 with the injection of the foamable resin 31.

  In the present embodiment, a fluid in a supercritical state is used as the foaming agent used for the foamable resin 31, but other physical foaming materials or chemical foaming agents can also be used. In addition, the foamable resin 31 may further contain reinforcing fibers that reinforce the foamable resin 31.

  The present invention is not limited to the embodiments exemplified above, and it goes without saying that various improvements and design changes can be made without departing from the scope of the present invention.

  The present invention relates to molding of a resin molded product in which a foamable resin is injected into a blow molded body to cause foaming, and is suitably applied to molding of a resin molded product such as a trunk board assembled to a vehicle body, for example. Is possible.

It is a schematic block diagram which shows the molding apparatus of the resin molded product which concerns on the 1st Embodiment of this invention. It is a perspective view which shows the movable mold | type of the said shaping | molding apparatus. It is a top view which shows four types of forms of the cutting blade in the said shaping | molding apparatus. It is a schematic block diagram which shows the injection apparatus of the said shaping | molding apparatus. It is the schematic which shows the state by which pressurized gas was supplied to the parison located in the shaping | molding die of the said shaping | molding apparatus. It is the schematic which shows the state in which the foaming resin was inject | poured in the said shaping | molding die, and the cutting blade act | operated. It is a schematic perspective view which shows the blow molded object in which the isolation | separation part was formed. 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. It is the schematic which shows the state by which foamable resin inject | poured in the said shaping | molding die was foam-molded. It is sectional explanatory drawing which expanded and showed the B section of FIG. It is a schematic block diagram which shows the modification of the shaping | molding apparatus of the said 1st Embodiment. It is a schematic perspective view which shows the blow molded object in which the isolation | separation part was formed in the shaping | molding apparatus of the said modification. It is a perspective view which shows the parison used with the shaping | molding apparatus of the resin molded product which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the extrusion head for extruding the parison of FIG. It is a perspective view which shows the core of the extrusion head of FIG. In the molding apparatus of the resin molded product which concerns on the 3rd Embodiment of this invention, it is the schematic 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 the schematic which shows the state in which foamable resin is inject | poured in the shaping | molding die of the shaping | molding apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Molding apparatus 10 Mold 11 Fixed mold 12 Movable mold 13 Core part 13c Cavity facing surface 14 Outer peripheral part 14a Inner surface of outer peripheral part 14b Upper and lower slits 14c Both side slits 16 Cavity 20 Parison 21 Extrusion head 23 Blow molding 23a Stretching of blow molding 23b Separation part or cut 24 Resin molded product 25 Blow pin 30 Injection device 31 Foamable resin 40, 41, 42, 43, 44 Cutting blade

Claims (13)

A parison made of a solid resin is extruded into a mold that is opened, and the mold is closed by sandwiching the parison, and then the parison is blow molded to form a hollow blow molded body, and the blow molded body is formed. Later, by injecting a foamable resin into the blow molded body, and after starting the injection of the foamable resin, moving the core portion of the mold by a predetermined amount so as to increase the volume of the cavity in the mold, A method for molding a resin molded article that expands the blow molded body by promoting foaming of a foamable resin,
A method for molding a resin molded product, comprising: forming a separation portion at a portion of the blow molded body that is to be stretched as the blow molded body expands before or after the core section starts moving. .   The method for molding a resin molded product according to claim 1, wherein the separation portion is formed on the blow molded body after the blow molded body is formed and before the movement of the core portion is started.   A fixed mold that forms a cavity in the mold, and a movable mold, and when either the fixed mold or the movable mold closes the mold, the fixed mold and the movable mold; The mold is closed with the other mold, and at least one of the fixed mold and the movable mold moves relative to the outer peripheral portion so as to increase the volume of the outer peripheral portion located on the outer periphery of the core portion and the cavity of the molding die. The mold having the possible core portion is used, and the separation portion is formed in the vicinity of an adjacent portion between a cavity facing surface of the core portion and an inner surface of the outer peripheral portion. 3. A method for molding a resin molded article according to 1 or 2.   The method for molding a resin molded product according to claim 3, wherein the separation portion is formed in a substantially square shape as a whole with respect to the blow molded body.   The method for molding a resin molded product according to any one of claims 1 to 4, wherein the foamable resin contains reinforcing fibers that reinforce the foamable resin.   The method for molding a resin molded product according to claim 1, wherein the foamable resin contains a physical foaming agent.   The method for molding a resin molded product according to claim 6, wherein the physical foaming agent is a fluid in a supercritical state. A mold that can be opened and closed, an extrusion head that extrudes a parison made of a solid resin into the mold that is opened, and a pressurized fluid is supplied into the parison after the mold is closed with the parison in between. A pressurized fluid supply means for forming a hollow blow-molded body, an injection means for injecting a foamable resin into the blow-molded body, and a core portion of the mold to expand the volume of the cavity of the mold. Core moving means for moving, and after injecting the foamable resin into the blow molded body, the core portion is moved so as to enlarge the volume of the cavity of the molding die, and foaming of the foamable resin is performed. A molding device for a resin molded product that promotes and expands the blow molded article,
It further comprises an incision means for forming a separating portion in a portion where the blow molded body is stretched with the expansion of the blow molded body before or after the start of movement of the core portion. Resin molded product molding equipment.   9. The molding of the resin molded product according to claim 8, wherein the separating portion is formed on the blow molded body by the cutting means after the blow molded body is formed and before the movement of the core portion is started. apparatus. The mold has a fixed mold and a movable mold,
One of the fixed mold and the movable mold is closed with the other of the fixed mold and the movable mold when the mold is closed, and at least one of the fixed mold and the movable mold. One is provided with an outer peripheral part located on the outer periphery of the core part and the core part movable with respect to the outer peripheral part so as to enlarge the volume of the cavity of the mold, and the cutting means includes the core part The molding apparatus for a resin molded product according to claim 8, wherein the molding apparatus is provided in the vicinity of an adjacent portion between the cavity facing surface of the outer periphery and the inner surface of the outer peripheral portion.   11. The molding apparatus for a resin molded product according to claim 10, wherein the incision unit is configured to form the separation portion in a generally square shape as a whole with respect to the blow molded body.   The said injection | pouring means inject | pours the foamable resin containing a physical foaming agent, The molding apparatus of the resin molded product in any one of Claims 8-11 characterized by the above-mentioned.   The apparatus for molding a resin molded product according to claim 12, wherein the injection means injects a foamable resin containing a fluid in a supercritical state as the physical foaming agent.

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