JP2008142990A - Method and apparatus for molding resin molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for molding a resin molding which prevents the lowering of the followability of a blow-molded article to the inner wall of a mold while foaming a foamable resin by the enlargement of a cavity on the basis of the mold action of the mold. <P>SOLUTION: The molten foamable resin 70 is supplied into the blow-molded article 41 in the mold 4. After that, the cavity 27 is enlarged on the basis of the mold action of the mold 4, and the blow-molded article 41 is expanded on the basis of foaming by the molten foamable resin 70. Before the enlargement of the cavity 27 on the basis of the mold action of the mold 4, on the basis of the mold 4, in the blow-molded article 41, one part on the side of the enlargement of the cavity 27 is retracted inside the blow-molded article 41 from the other part on the same side to form a retracted part 41a in the blow-molded article 41. When the cavity 27 is enlarged on the basis of the mold action of the mold 4, the retracted part 41a is expanded to make it follow the inner wall of the mold 4 exactly. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  In the molding method of the resin molded product, as shown in Patent Document 1, a hollow blow molded body is formed by taking a tube-shaped parison as a preformed body into a cavity of a mold and performing blow molding, It is known that the blow molded body is filled with expandable beads while venting air and supplied with steam to be foam welded. According to this, the surface layer portion of the resin molded product becomes a blow molded product (film), and the surface properties (smoothness), strength, and the like of the resin molded product can be stably increased.

On the other hand, as a molding method of a resin molded product, in order to promote foaming and increase the volume of the resin molded product, the cavity is filled based on the mold movement (movable mold movement) after filling the cavity with the foamable resin. (So-called core back) has been proposed. When this molding method is applied to the above-described molding method, a resin molded product that can increase the surface property, strength, etc. of the surface layer portion and increase (adjust) the volume can be obtained.
JP 2004-284149 A

  However, in the above molding method, generally, the cross-sectional area of the cavity facing the mold movement direction of the mold is maintained constant throughout the front and back of the core back, and before the core back, the blow molded body is applied to the entire cavity inner wall. Has been pressed and cooling of the blow-molded body has started by the mold (decrease in ductility), and the blow-molded body is particularly near the cavity inner wall that appears newly with the core back (front side of the peripheral edge of the movable mold inner wall) As a whole, the tension is increased. For this reason, foaming of the foamable resin due to the increase in the cavity based on the mold operation of the mold is suppressed, and the followability of the blow molded body to the vicinity of the peripheral edge of the mold inner wall, particularly the movable mold inner wall tends to be lowered. .

The present invention has been made in view of the above circumstances, and a first technical problem thereof is a blow molded product for the inner wall of the mold while achieving foaming of the foamable resin by increasing the cavity based on the mold operation of the mold. It is in providing the molding method of the resin molded product which prevents that the followable | trackability falls.
A second technical problem is to provide a molding apparatus used in the molding method of the resin molded product.

In order to achieve the first technical problem, in the present invention (the invention according to claim 1),
A tube-shaped preform formed using a melted non-foamable resin is suspended, and the preform is taken into a cavity of a molding die to perform blow molding to form a hollow blow-molded body, The blow-molded product is expanded based on the foaming of the melt-foamable resin by supplying the melt-foamable resin into the blow-molded body in the mold and then increasing the cavity based on the mold operation of the mold. A method of molding a resin molded product,
Before increasing the cavity based on the mold operation of the mold, based on the mold, part of the blow molded body on the side where the cavity is increased is made more than other areas on the same side. Retracted inward of the blow molded body to form a retracted part,
In addition, as the cavity is increased based on the mold operation of the mold, the retracted portion of a partial region of the blow molded body is expanded.

  With the above-described configuration, when the cavity is increased based on the mold operation of the mold, the retracted part of the partial area of the blow molded product is accurately placed on the inner wall surface of the mold as a margin for expansion (elongation allowance). It will expand smoothly while following.

  According to a preferred aspect of the present invention, after the preform is taken into the cavity of the mold and before the cavity is increased, one of the preforms on the side where the cavity is increased is provided. By setting the partial area to be inwardly retracted from the other area on the same side, the partial area of the blow molded body is retracted to the inner side of the blow molded body from the other area. The structure which makes it the state which can be taken can be taken (corresponding to claim 2). With this configuration, after the preform is taken into at least the cavity of the mold, a recessed portion is formed in a partial region on the side where the cavity is increased, so that the thickness increases with the formation of the recessed portion. Can be made thinner than the case where the pre-formed body is taken into the cavity and at the same time the recessed portion is formed in a partial region thereof, and not only the followability of the blow-molded body to the inner wall of the mold can be prevented. (Accurate core back) Even if the expansion of a partial region (recessed portion) of the blow molded body is limited to the other region, the meat of the portion (surface layer portion) is based on the thin portion of the blow molded body. Thickening can be prevented.

  As a preferred aspect of claim 1, when the cavity is increased based on the mold operation of the mold, the other region of the blow molded body is maintained in the same state regardless of the mold operation of the mold. Further, it is possible to adopt a configuration in which only a partial area of the blow molded body is expanded to the position of the other area of the blow molded body based on the mold operation of the mold (corresponding to claim 3). With this configuration, it is possible not only to prevent the followability of the blow-molded body with respect to the inner wall of the mold (a precise core back) but also to easily mold a molded product having no protrusion.

  According to a preferred aspect of the present invention, the mold includes a first mold, a second mold, and a third mold in series in that order, and the first mold is a recess for forming the cavity. With the opening directed toward the second and third molds, and the second mold has a recess corresponding to the recess in the first mold. And a through-hole that is smaller than the bottom wall of the recess is formed in the bottom wall of the recess so as to penetrate in the arrangement direction of the first, second, and third molds. The third mold has a projecting portion that can penetrate the through hole of the second mold and project into the recess of the second mold, and the preform is placed in the cavity of the mold. When taking in, the second and third molds are moved relatively away from the first mold, and a part of the blow molded body is made to be blown more than the other part. In the state of being retracted to the inner side of the body, the projecting portion of the third mold is projected into the recess of the second mold, and the blow molded body is inside the recess and the inner surface of the bottom wall in the recess And the protrusion of the third mold in the recess of the second mold when the recessed portion of the partial area of the blow molded body is expanded along the protrusion. It is possible to adopt a configuration that is reduced as compared with the case before the recessed portion of the partial region in FIG. With this configuration, the action according to the first aspect can be produced using a specific mold.

  As a preferred aspect of claim 1, when the preform is taken into the cavity of the mold, the front end surface of the protrusion of the third mold is flush with the inner surface of the bottom wall of the recess of the second mold. The projecting portion of the third mold is projected into the recess of the second mold after the preform is taken into the cavity of the mold and before the cavity is increased. Can be taken (corresponding to claim 5). With this configuration, the action according to the second aspect can be produced using a specific mold.

  As a preferred aspect of claim 1, the protrusion amount of the protrusion in the third mold in the recess of the second mold is reduced as compared with the case before expanding the retracted portion of the partial region in the blow molded body. It is possible to adopt a configuration in which the distal end surface of the third-type projecting portion is retracted to the inner surface of the bottom wall of the recess (corresponding to claim 6). With this configuration, the action according to the third aspect can be produced using a specific mold.

  As a preferred aspect of claim 1, a configuration in which reinforcing fibers are contained in the melt-foamable resin can be adopted (corresponding to claim 7). With this configuration, when the mold is opened, the reinforcing fiber rises and the molded product expands (apparent volume increases) (spring back phenomenon). This phenomenon promotes foaming of the melt-foamable resin. Can do.

  As a preferable aspect of claim 1, the melt-foamable resin can take a configuration in which a physical foaming agent is mixed in the resin (corresponding to claim 8). With this configuration, the foam cell diameter inside the molded product can be reduced.

  As a preferred aspect of claim 1, it is possible to adopt a configuration in which the physical foaming agent is a supercritical fluid (corresponding to claim 9). With this configuration, the foamed cell diameter inside the molded product can be further reduced by utilizing the properties of the supercritical fluid.

In order to achieve the second technical problem, in the present invention (the invention according to claim 10),
A preform molding machine that uses a melted non-foamable resin and hangs a tubular preform, and a preform molded by the preform molding machine is taken into a cavity to form the preform. A mold that is molded into a predetermined shape as a hollow blow-molded body, and a melt-foamable resin supply means that feeds a melt-foamable resin into the blow-molded body in the mold. In the molding apparatus set to increase the cavity based on the mold operation when the foamable resin supply means supplies the melt-foamable resin into the blow molded body in the mold,
The mold includes a first mold, a second mold, and a third mold in series in that order,
The first mold has a recess for forming the cavity, with the opening facing the second and third molds;
The second mold has a recess corresponding to the recess of the first mold in a state in which the opening faces the first mold, and the bottom wall portion of the recess is more than the bottom wall portion of the recess. The reduced through hole is formed so as to penetrate in the arrangement direction of the first, second and third molds,
The third mold has a projecting portion capable of projecting into the recess of the second mold through the through hole of the second mold;
The second and third molds are set to move relative to the first mold when the preform is taken into the cavity of the mold;
The protrusion of the third mold protrudes into the recess of the second mold before the cavity is increased based on the mold movement of the mold, and based on the mold movement of the mold. When the cavity is increased, the protruding amount of the protruding portion into the recess of the second mold is set to be smaller than the state before the cavity is increased. With this configuration, by using the apparatus, it is possible to prevent the foamable resin from foaming due to an increase in the cavity based on the mold operation of the mold and to prevent the followability of the blow molded body with respect to the inner wall of the mold.

  As a preferred aspect of the tenth aspect, the configuration according to the eleventh aspect can be adopted. With this configuration, the same function and effect as those of the second to fifth aspects of the present invention can be obtained.

  According to the present invention (the invention according to claim 1), the foamable resin is foamed by increasing the cavity based on the mold operation of the mold, and the followability of the blow molded body to the mold inner wall is prevented from being lowered. It is possible to provide a method for molding a resin molded product.

  According to this invention (invention which concerns on a claim), the shaping | molding apparatus used for the shaping | molding method of the resin molded product which concerns on Claim 1 can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the shaping | molding apparatus 1 which concerns on this embodiment is demonstrated. As shown in FIG. 1, the molding apparatus 1 has a molten solid resin (for example, polypropylene) as a molten non-foamable resin preformed into a tube shape to form a soft preform (hereinafter referred to as a parison) 2. A parison extruder 3 to be extruded into the mold, a mold 4 that molds the parison 2 suspended from the parison extruder 3 into a predetermined shape, and a melt-foamable resin 70 that is formed inside the mold 4 and that leads to the parison 2 A resin supply structure 5 and a resin supply device 7 (a melt-foamable resin supply means) for feeding the melt-foamable resin 70 to the resin supply structure 5 are provided.

  As shown in FIG. 1, the parison extruder 3 includes an accumulator head 9, and a die 10 is provided below the accumulator head 9. The die 10 is formed with a central hole 11 penetrating in the vertical direction (thickness direction), and a core 12 is disposed in the central hole 11. A core rod 13 is connected to the core 12, and the core rod 13 extends upward through the inside of the accumulator head 9, and an upper end portion of the core rod 13 is a cylinder device above the accumulator head 9 (fixed member not shown). (Fixed) 14. The outer peripheral surface of the core 12 and the inner peripheral surface of the central hole 11 of the die 10 form an annular extrusion hole 15, and the annular width of the extrusion hole 15 is adjusted and set by driving adjustment of the cylinder device 14. . An annular material storage portion 16 is formed in the accumulator head 9 so as to be continuous with the annular extrusion hole 15. A material supply unit 17 is connected to the material storage unit 16, and a solid resin (for example, polypropylene) as a non-foamable resin is supplied to the material storage unit 16 by the material supply unit 17. . Further, an annular passage 18 is formed inside the accumulator head 9 above the material storage portion 16, and the annular passage 18 continues to the material storage portion 16. A ring plunger 19 is slidably fitted in the annular passage 18, and the ring plunger 19 pushes the solid resin supplied into the material reservoir 16 toward the annular extrusion hole 15. It is to be driven in the vertical direction by a cylinder device (fixed to a fixing member not shown) 20 disposed above the accumulator head 9.

  As shown in FIG. 1, the mold 4 includes a fixed mold (first mold) 21, a first movable mold (second mold) 22, and a second movable mold (third mold) 23. . As shown in FIGS. 1 and 2, the fixed die 21 is formed in a thick plate shape, and its inner surface 21a is formed as a flat surface facing in the horizontal direction. The inner surface 21a is formed in a rectangular shape when viewed from the front, and a concave portion 21A having a rectangular shape when viewed from the front is formed in the inner surface 21a in a state where the outer shape of the inner surface 21a is reduced. ing. A blow pin insertion hole 29 is formed in the fixed mold 21A. The blow pin insertion hole 29 is formed in the upper part of the fixed mold 21 so as to extend in the vertical direction. The blow pin insertion hole 29 communicates the recess 21A of the fixed mold 21 with the outside. A blow pin 30 (having a passage formed in the axial direction) is slidably inserted into the blow pin insertion hole 29, and the blow pin 30 enters the recess 21A by a driving device (not shown). The entry position and the exit position for exiting from the recess 21A can be taken. A compressed air source (not shown) and the atmosphere are connected to the blow pin 30 via a switching device (not shown). By switching the switching device, the blow pin 30 has a function of supplying compressed air, air vent ( Natural exhaust) function is to be demonstrated selectively. In this case, forced exhaust may be performed instead of natural exhaust.

  As shown in FIGS. 1, 3, and 4, the first movable die 22 is formed in a thick plate shape corresponding to the fixed die 21, and the inner surface 22a and the rear surface 22b are flat surfaces. In the state is oriented horizontally. The first movable mold 22 is disposed with its inner surface 22a facing the inner surface 21a of the fixed mold 21. The first movable mold 22 is fixed to the fixed mold 21 by a drive mechanism (not shown). It can be moved toward and away. The first movable mold 22 is formed with a recess 22A on the inner surface 22a for configuring the cavity 27 in cooperation with the recess 21A of the fixed mold 21. The recess 22A is partitioned by a flat bottom wall inner surface 22Aa and a peripheral wall inner surface 22Ab rising from the bottom wall inner surface 22Aa. The opening of the recess 22A is a recess of the fixed mold 21 in the front view. It is substantially equal to the shape and size (area) of the 21A opening. Further, the bottom wall portion (recess bottom wall portion) 22Ac of the first movable mold 22 is formed with a through hole 22B having a rectangular shape in front view so as to extend in the thickness direction (left and right direction in FIG. 1). Has been. One end of the through hole 22B is opened to the back surface 22b side, and the other end is opened in the recess 22A. The opening of the through hole 22B is made smaller than the opening of the recess 22A, and the bottom wall inner surface 22Aa exists on the outer peripheral side of the other end of the through hole 22B.

  As shown in FIGS. 1, 3 and 4, the second movable mold 23 is disposed on the back surface 22b side of the first movable mold 22 and is attached to the first movable mold 22 by a drive mechanism (not shown). On the other hand, it can move toward and away. The second movable mold 23 includes a main body portion 23a and a protruding portion 23b protruding from the inner surface of the main body portion 23a. Corresponding to the first movable mold 22, the main body 23a is formed as a thick plate-like body having a square shape in front view, and the inner surface thereof is oriented in the horizontal direction. The protrusion 23b protrudes from the inner surface of the main body 23a with a front view shape (rectangular shape) corresponding to the through hole 22B of the first movable die 22, and the protrusion 23b is slidably fitted into the through hole 22B. Are combined. When the inner surface of the second movable mold 23 is in contact with the back surface 22b of the first movable mold 22, the projecting portion 22b enters the recess 22A and projects from the inner surface 22Aa of the recess bottom wall. At that time, an annular groove is formed between the outer peripheral surface of the tip of the protrusion 22b and the inner surface 22Ab of the peripheral wall of the first movable die 22. The protruding amount and the cross-sectional area of the protruding portion 22B are set in relation to the increased cavity volume formed with the core back described later.

  In the present embodiment, when the mold 4 is opened, the protrusion 23b in the second movable mold 23 is fitted into the through hole 22B of the first movable mold 22, and the protrusion 23b The front end is projected from the bottom wall inner surface 22Aa of the first movable mold 22 in the recess 22A. When the cavity 27 is increased (core back) with the parison 2 set (clamped) in the cavity 27, the first movable mold 22 and the fixed mold 21 hold the parison 2 in the state. 2 The protrusion 23b of the movable mold 23 moves by a certain amount in the mold opening direction, and the volume of the protrusion 23b occupied in the recess 22A of the first movable mold 22 is changed. The details will be described in the description of the molding method.

  As shown in FIGS. 1, 5, and 6, the resin supply structure 5 includes a resin supply passage 32, a shutter valve 33, and a plunger 34. The resin supply passage 32 extends in the thickness direction of the fixed mold 21 at a position lower than the substantially center of the fixed mold 21, and the resin supply passage 32 includes an outer surface of the fixed mold 21 and a bottom surface of the recess 21A. It penetrates between. Specifically, the resin supply passage 32 includes a large-diameter portion 35 that extends from the bottom surface of the recess 21A to the inside by a certain distance, a medium-diameter portion 36 that continues to the large-diameter portion 35 as a stepped hole, and a medium-diameter thereof. A small-diameter portion 37 having one end opened on the inner peripheral surface of the portion 36 and the other end opened on the outer surface of the main body portion 23a.

  The shutter valve 33 is provided so as to be movable back and forth with respect to the large diameter portion 35. The shutter valve 33 is driven by a driving device 38 at a position adjacent to the medium diameter portion 36, and when the shutter valve 33 enters the large diameter portion 35, the large diameter portion 35 and the medium diameter portion 36 are driven. When communication with the portion 36 is interrupted and the shutter valve 33 is retracted from the large diameter portion 35, the large diameter portion 35 and the medium diameter portion 36 are in communication. The plunger 34 is slidably fitted in the medium diameter portion 36. The plunger 34 can take a forward position near the large-diameter portion 35 and a retracted position on the outer surface side of the main body 23a with respect to the forward position by a drive device 47 (see FIG. 5). One end opening of the small diameter portion 37 is closed by the side surface of the plunger 34, and the medium diameter portion 36 and the small diameter portion 37 are communicated with each other at the retracted position.

  As shown in FIG. 1, the resin supply device 7 (screw cylinder type) is connected to the resin supply passage 32 of the fixed mold 21. The resin supply device 7 supplies (injects) a melt-foamable resin (thermoplastic resin) 70 to the resin supply passage 32 of the fixed mold 21 based on existing functions (heating, pressure function, etc.). In order to supply the melt-foamable resin 70, the resin supply device 7 is supplied with a resin 39 and a physical foaming agent that vaporizes during molding. Polypropylene or the like is used as the resin 39, and in this embodiment, long fibers are further mixed into the resin as reinforcing fibers. As the physical foaming agent, a supercritical fluid is used to perform ultrafine foam molding, and the supercritical fluid is to be supplied from the supercritical fluid unit 40 to the resin supply device 7. Specifically, as the supercritical fluid, CO2 or N2 in a supercritical state (a state exceeding the critical pressure and critical temperature) is used, and the supercritical fluid has its properties (viscosity as a liquid). In addition, the resin 39 is mixed in the resin 39 in order to utilize the property of having both the dissolving power and the intense molecular motion as gas. The supply timing of the melt-foamable resin 70 by the resin supply device 7 is performed by controlling the drive device 38 of the shutter valve 33 and the drive device 47 of the plunger 34. Details will be given in the description of the molding method.

  Next, this molding method will be described using the molding apparatus 1.

  First, as shown in FIG. 1, the parison 2 is suspended between the molds 4 in the mold open state. At this time, the mold open state of the mold 4 is such that the protrusion 23b of the second movable mold 23 is fitted into the through-hole of the first movable mold 22 in consideration of the holding of the parison 2 in the subsequent process. The fixed mold 21 is separated from the fixed mold 21 by a certain length in the horizontal direction. In addition, the parison 2 is extruded from the die 10 in a cylindrical shape downward from the die 10 by the parison extruder 3, and the wall thickness of the parison 2 at that time is approximately equal.

  When the parison 2 is suspended between the molds 4 in the mold open state, the first movable mold 22 and the second movable mold 23 are moved toward the fixed mold 21 and the mold is closed as shown in FIG. Blow molding is performed in the mold closed state. In this mold closing, the upper and lower ends of the parison 2 are sandwiched between the first movable mold 22 and the fixed mold 21, whereby the upper and lower ends of the parison 2 are closed, and the majority of the parison 2 is formed in the cavity 27. Stored inside. In blow molding, after the mold is closed, the front end portion of the blow pin 30 penetrates into the parison 2 in the cavity 27, and compressed air is supplied into the parison 2 using the blow pin 30. By supplying this compressed air, the parison 2 is inflated and pressed against the inner surface of the cavity 27 in a mold-closed state, thereby forming a blow molded body 41 (blow shaping). At this time, since the tip of the projecting portion 23b of the second movable mold 23 projects from the bottom wall inner surface 22Aa in the recess 22A (27) of the first movable mold 22, the parison 2 In 22A, the blow molded body 41 is pressed along the tip of the protruding portion 23b of the second movable mold 23, so that the blow molded body 41 has a range (partial region) of the protruding portion tip surface 23bt of the second movable mold 22. ), The retracted portion 41a is formed in the blow molded body 41 by retracting inward from the other range (other region) on the side where the projecting portion 23b exists (the side where the cavity 27 is increased) (see FIG. 7).

  With this blow molding, the shutter valve 33 is opened as shown in FIGS. 6 and 8 at the time when the blow molded body 41 is substantially formed. Along with blow molding, utilizing the fact that part of the parison 2 enters the large diameter portion 35 of the resin supply passage 32 while being thinned, the support of the shutter valve 33 is removed from the parison 2 in the large diameter portion 35, This is because it breaks due to the action of compressed air in the parison 2. In this case, the opening operation of the shutter valve 33 is performed, for example, by capturing (measuring) that a predetermined time has elapsed since the supply of compressed air by the blow pin 30 was started.

When the blow molded body 41 is molded (specifically, when the shutter valve 33 is opened), as shown in FIG. 8, the melt-foamable resin 70 is fed from the resin supply device 7 into the blow molded body 41. It is injected. Prior to the injection of the melt-foamable resin 70, the supply of compressed air to the blow pin 30 is stopped and the blow pin 30 is withdrawn from the inside of the mold 4 (inside the cavity 27). The reason why the blow pin 30 is withdrawn from the inside of the mold 4 is to use the blow pin 30 as an air bleeding means. In other words, after the blow molded body 41 is formed, the melt-foamable resin 70 cannot be smoothly filled into the blow-molded body 41 unless the air in the blow-molded body 41 is discharged along with the injection of the melt-foamable resin 70. For this reason, the blow pin 30 is not embedded in the injected melt-foamable resin 70 in order to accurately use the blow pin 30 as an air bleeding means. For this reason, prior to the injection of the melt-foamable resin 70 into the blow molded body 41, the tip of the blow pin 30 is withdrawn from the blow molded body 41 into the blow pin insertion hole 29 and into the blow molded body 41. Along with the start of injection of the melt-foamable resin 70, the air in the blow molded body 41 is utilized using the through hole of the blow molded body 41 (hole through which the blow pin 30 has passed) and the blow pin 30 in the blow pin insertion hole 29. Unplugging is performed. Further, when the molten foamable resin 70 is injected into the blow molded body 41, the plunger 34 in the medium diameter portion 36 in the resin supply passage 32 is moved backward, and the small diameter portion 37 and the medium diameter portion 36 are communicated with each other. . As a result, the small diameter portion 37, the medium diameter portion 36, and the large diameter portion 35 are in communication with each other, and a high-pressure molten foamable resin 70 is injected into the blow molded body 41 through them. At this time, since the pressure in the cavity 27 is lower than the critical pressure, the foamable resin supplied into the blow molded body 41 is foamed on the basis of the supercritical fluid contained in the blown resin 41.
The injection of the melt-foamable resin 70 into the blow molded body 41 by the resin supply device 7 is basically based on the fact that the blow molded body 41 is filled with the melt-foamable resin 70 in the mold closed state. Stopped. This stop determination is determined using various information such as the pressure state in the blow molded body 41.

  As shown in FIG. 9, when the foamable resin in the blow molded body 41 reaches a filled state or a predetermined state before the filling (including the start time of injection of the foamable resin), a core back is performed. As shown in FIG. 2, in a state where the first movable mold 22 and the fixed mold 21 sandwich the upper and lower ends of the blow molded body 41 (parison 2), the second movable mold 23 is a predetermined length from the first movable mold 22. Spaced apart. As a result, the protruding portion 23b of the second movable mold 23 retreats until the tip end surface 23bt thereof is flush with the bottom wall inner surface 22Aa of the first movable mold 22, and the volume occupied by the protruding portion 23b until then is new. The cavity 27 volume is increased. Along with this, the foamable resin is further expanded by the increase in the cavity 27 based on the supercritical fluid, and the volume thereof is increased. As (extension allowance), it expands following the withdrawal of the protrusion 23b of the second movable mold 23, and is finally pressed against the entire inner wall of the recess 22A of the second movable mold 22 (see FIG. 10). In this case, as shown in FIG. 11, the internal stress of the long fibers 43 forcedly aligned along the flow direction based on the resin flow before the core back is released along with the core back. As shown in FIG. 12, the long fibers 43 are relaxed in their orientation and rise, and the molded product expands (apparent volume increases) (spring back phenomenon). This phenomenon is a foaming resin. Will promote foaming.

  Thereafter, when the operation of the core back is finished and the expansion of the blow molded body 41 based on the foaming of the foamable resin in the cavity 27 is finished, the blow molded body 41 and the foamable resin inside thereof are awaited to be molded. The molded product is removed from the mold 4.

  13 to 15 are the second embodiment, FIGS. 16 and 17 are the third embodiment, FIGS. 18 to 20 are the fourth embodiment, FIGS. 21 to 23 are the fifth embodiment, and FIG. 24 is the sixth embodiment. FIG. 25 shows a seventh embodiment. In each of the embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The second embodiment shown in FIGS. 13 to 15 shows a modification of the first embodiment. In the second embodiment, as shown in FIGS. 13 and 14, the tip surface 23 bt of the projecting portion 23 of the second movable mold 23 is the first movable mold 22 from the reception of the parison 2 to the end of blow molding. It is flush with the bottom wall inner surface 22Aa of the recess 22A. Then, after the blow molding, as shown in FIG. 15, the main body portion 23 a of the second movable mold 23 is moved closer to contact with the back surface 22 b of the first movable mold 22, and the protrusion of the second movable mold 23 The tip surface 23bt of the portion 23b presses the blow molded body 41 toward the inside of the cavity 27. Thereby, in the blow molded body 41, a recessed portion 41a is formed in the range (partial region) of the distal end surface 23bt of the protruding portion 23b. At this time, since the blow molded body 41 is pressed against the inner wall of the cavity 27 and a certain degree of tension is secured, the formation of the retracted portion 41a based on the pressing by the projecting portion 23b causes the retracted portion 41a, particularly the projecting portion. The portion 41aa located on the side surface of the distal end portion 23b is thinner than in the case of the first embodiment (see FIGS. 14 and 15).

  In this case, in this embodiment, the protrusion timing of the protrusion 23b into the recess 22A in the first movable mold 22 (the pressing timing by the protrusion front end surface 23bt with respect to the blow molded body 41 (the formation timing of the retracted portion 41a)). Is performed after the blow molding is completed, but the timing of the parison 2 is determined depending on the material used for the parison 2, the molding conditions, the amount of protrusion of the protrusion 23b into the recess 22A in the first movable mold 22, and the like. The time is adjusted appropriately until the back core back.

  When the protrusion front end surface 23bt of the second movable mold 23 presses the blow molded body 41 toward the inside of the cavity 27 to form the retracted portion 41a, thereafter, as in the case of the first embodiment, blow molding is performed. When molten foamable resin 70 is injected from the resin supply device 7 into the body 41 and filled (see FIGS. 8 and 9), core back is performed by the second movable mold 23 (projecting portion 23b) (see FIG. 8). (See FIG. 10). As a result, the retracted portion 41a of the blow molded body 41 follows well with the withdrawal of the protruding portion 23b from the recess 22A, and is finally pressed against the inner wall of the recess 22A. Also in the case of this core back, the second movable mold 23 is retracted until the projecting end surface 23bt thereof is flush with the bottom wall inner surface 22Aa of the recess 22A in the first movable mold 22, as shown in FIG. However, the portion 41aa is prevented from forming an excessively thick portion based on the thinning of the portion 41aa located on the side surface of the tip portion of the protruding portion 23b in the above-described retracted portion 41a.

  The above content will be described more specifically with reference to FIGS. As shown in the first embodiment, when the parison 2 is taken into the mold 4, the tip of the projecting portion 23 b in the second movable mold 23 is previously removed from the inner surface 22 Aa of the recess bottom wall in the first movable mold 22. In the case of projecting (see FIGS. 1 and 7), as a core back mode, as shown in FIG. 26, the projecting portion front end surface 23bt in the second movable mold 23 is formed on the bottom wall of the recess in the first movable mold 22. If the inner surface 22Aa is further retracted, there is a restriction that the retracted portion 41a expands to form a projecting portion in the shape of the final molded product, but the entire retracted portion 41a is properly It expands, and no slack or excessively thickened portion is formed on the blow molded body 41 (final molded product). In FIG. 26, illustration of the melt-foamable resin 70 present in the blow molded body 41 is omitted.

  On the other hand, as shown in FIG. 27, the second movable mold 23 is withdrawn until the protrusion tip end surface 23bt is flush with the recess bottom wall inner surface 22Aa of the first movable mold 22, and the blow molded body 41 When trying to eliminate the restriction that the protruding portion is formed in the (final molded product), among the retracted portion 41a, particularly the portion 41aa located on the side surface of the tip portion of the protruding portion 23b, after the core back, There is a possibility that the blow molded body 41 may be loosened or have an excessively thick portion 41aa ′. In FIG. 27 as well, illustration of the melt-foamable resin 70 present in the blow molded body 41 is omitted.

  Therefore, in the second embodiment, as shown in FIGS. 13 to 15, the parison 2 or the blow molded body 41 that is in a certain tension state is pressed by the projecting portion front end face 23 bt in the second movable mold 23, and the retracted portion. By forming 41a, the portion 41aa of the retracted portion 41a, in particular, located on the side surface of the tip of the projecting portion 23b is thinned (see FIG. 15). As shown in FIG. 27, the excessively thick portion 41aa ′ is not formed. On the other hand, as shown in FIG. 28, when the parison 2 is drooped, it is conceivable that the expected portion of the wall thickness increase is thinned in advance in the parison 2 (the thinned portion is indicated by reference numeral 41ab). In this case, when the degree of thinning must be increased due to the relationship with the amount of core back, the drawdown of parison 2 (the weight of the thinned portion 41ab cannot be supported and the thinned portion 41ab is extended, or in some cases 2 may be cut or dropped.

  The third embodiment shown in FIGS. 16 and 17 shows a modified example of supplying compressed air at the time of blow molding and removing air at the time of injection of foamable resin. In the third embodiment, the blow pin 30 has the same configuration as that of the first embodiment, but the blow pin 30 is used only for supplying compressed air, not used for releasing air, At that time, the blow pin 30 is only retracted into the blow pin insertion hole 29 (the same as the first embodiment with respect to advancement and retraction). On the other hand, an air discharge mechanism 51 is provided inside the second movable mold 23 for air bleeding. The air discharge mechanism 51 includes a working chamber 52, an air discharge passage 53 that communicates the inside of the working chamber 52 with the atmosphere, a plurality of through holes 54 that communicate between the working chamber 52 and the cavity 27, and the working chamber 52. And a drilling member 55 to be disposed. The perforating member 55 includes a sliding portion 56 that slides on the working chamber 52 by a drive mechanism (not shown) and a plurality of tapered perforating pins 57 that protrude from the sliding portion 56. 16, the sliding portion 56 closes the opening of the air discharge path 53 and does not discharge air, while the plurality of punching pins 57 includes the plurality of through holes 54 and the blow molded body 41. Will penetrate. When the foaming resin is injected after the blow molding is completed, as shown in FIG. 17, the punching member 55 moves backward, and the sliding portion 56 opens the opening of the air discharge path 53, thereby making a plurality of punching holes. The pin 57 exits from the blow molded body 41. As a result, the blow molded body 41 and the air discharge path 53 communicate with each other, and the air in the blow molded body 41 is discharged to the outside through the air discharge path 53 as the foamable resin is injected. In FIG. 17, the arrows indicate the discharge flow of air.

  The fourth embodiment shown in FIGS. 18 to 20 shows a case where the air vent hole 58 is previously formed in the molding die 4 (fixed die 21 and first movable die 22). Recesses 59a and 59b having a semicircular cross section are formed in the upper mating surfaces of the fixed mold 21 and the first movable mold 22, respectively. When the two 21 and 22 are abutted with each other, the air vent hole 58 is cooperated. To be formed. When using this mold 4, in the mold open state of the mold 4, the pin 60 that can be fitted into the air vent hole 58 is placed on the die of the above-described parison extruder with its axial direction directed vertically. (In FIG. 18, only the pins are shown, and the support relationship with the die and the like is not shown). Then, the parison 2 is pushed out so that the pin 60 penetrates the upper part of the parison. In this state, the first and second movable molds 22 and 23 are moved toward the fixed mold 21, and the first movable mold 22 is moved. In addition, the parison 2 is sandwiched between the fixed mold 21 and the pin 60, and the pin 60 is fitted in the air vent hole 58 formed by the first movable mold 22 and the fixed mold 21. As a result, even if the air vent hole 58 is formed in the mold 4 in advance, it is blocked by the pin 60, so that the blow molding including the molding of the air vent hole 58 is performed appropriately and reliably (FIG. 19). reference). After the blow molding, when the foamable resin is injected into the blow molded body 41, the pin 60 is removed from the air vent hole 58 prior to the injection. Thereby, with the injection of the foamable resin, the air in the blow molded body 41 is discharged, and the foamable resin is smoothly filled into the blow molded body 41 (see FIG. 20). Of course, the pin 60 can also be used as a blow pin.

  The fifth embodiment shown in FIGS. 21 to 23 also shows that the air vent hole 58 is formed in the mold 4 in advance. A first hole 61 that continues to the cavity 27 as the air vent hole 58 in the mold 4, and a plurality of second holes 62 that continue to the first hole 61 and allow the first hole 61 to communicate with the atmosphere. The pins 63 are inserted into the plurality of second holes 62, respectively. When using such a mold 4, the parison 2 is sandwiched between the mold 4 (first and second movable molds 22 and 23), and then the pin 63 is inserted deeper to penetrate the parison 2. The second holes 62 are closed. Then, if blow molding is performed, each second hole 62 is closed, so that blow molding is appropriately performed and a blow molded body 41 is obtained (see FIG. 22). When the foamable resin is injected into the blow molded body 41 after blow molding, the pins 63 are pulled out from the second holes 62 prior to that. Thereby, with the injection of the foamable resin, the air in the blow molded body 41 is discharged, and the foamable resin is smoothly filled into the blow molded body 41 (see FIG. 23).

  The sixth embodiment shown in FIG. 24 shows a method for forming a fracture hole for injecting a foamable resin into the blow molded body 41. In the sixth embodiment, as the resin supply passage 32, the large-diameter portion 35 is omitted, and the medium-diameter portion 36 is opened to the outside from the front end surface of the protruding portion 23b of the fixed mold 21, and the opening is made of resin. In a state where the foamable resin is not supplied from the supply device 7, the supply device 7 is closed by the plunger 34. At this time, the opening of the small diameter portion 37 is also closed by the side surface of the plunger 34. On the other hand, a cylindrical portion (cylindrical portion) 64 is provided on the distal end surface of the protruding portion 23b of the fixed mold 21, and the cylindrical portion 64 faces the opening of the medium diameter portion 36 therein. Are arranged as follows. As a result, if the parison 2 is stored in the cavity 27 and then compressed air is supplied into the parison 2 (blow molding), a part of the parison 2 enters the cylindrical portion 64 and the portion that enters the parison 2 is thinned. Thereafter, if the plunger 34 is retracted in the direction of the arrow in FIG. 24, the parison 2 that has entered the cylindrical portion 64 is not supported, and therefore breaks based on the pressure of the compressed air in the parison 2. As a result, fracture holes are formed in the parison 2, that is, the blow molded body 41. At the same time, the plunger 34 opens the opening of the small diameter portion 37, and the foamable resin enters the blow molded body 41 through the medium diameter portion 36 and the fracture hole. As described above, in this embodiment, it is possible to form the breakage hole of the blow molded body 41 and supply and stop the foamable resin only by the plunger 34, and the shutter valve 33 as in the first embodiment. Need not be provided.

  The seventh embodiment shown in FIG. 25 shows a modification of the sixth embodiment. In the seventh embodiment, the tip end surface of the plunger 34 has a sharp shape, and protrudes forward from the cylindrical portion 64 when the foamable resin is not supplied from the resin supply device 7. Thereby, the retreating amount of the plunger 34 (displacement amount of the parison 2 portion entering the cylinder portion 64) can be lengthened, and the parison 2 (blow molded body 41) can be easily broken. In this case, the supply of the foamable resin from the resin supply device 7 is started when the pointed portion of the plunger 34 faces the small diameter portion 37.

  The molded article molded in each embodiment can be used for a wide range of applications such as for automobiles, building materials, household appliances, daily goods, etc. In each application, the molded article starts with reinforcement, Functions such as heat insulation, sound insulation, vibration isolation, and shock absorption can be exhibited.

The whole block diagram concerning a 1st embodiment. The figure which looked at the fixed type | mold which concerns on 1st Embodiment from the inner surface side. The perspective view which shows the relationship between a 1st movable type and a 2nd movable type. The figure which looked at the 1st movable type and the 2nd movable type from the inner surface side. Explanatory drawing explaining the resin supply structure which concerns on 1st Embodiment. Explanatory drawing explaining the partial fracture | rupture process of the blow molding in the resin supply structure which concerns on 1st Embodiment. Explanatory drawing explaining a blow molding process. Explanatory drawing which shows the injection process of the foamable resin in a blow molding body. Explanatory drawing which shows the state with which foamable resin was filled in the blow molding body. Explanatory drawing which shows the state by which the core back was performed from the state of FIG. Explanatory drawing which shows the state of the blow molded object before a core back, and the long fiber inside it. Explanatory drawing which shows the state of the blow molded object after a core back, and the long fiber inside it. Explanatory drawing explaining the acceptance process of the parison by the shaping | molding die under 2nd Embodiment. Explanatory drawing explaining the blow molding process under 2nd Embodiment. Explanatory drawing explaining the protrusion process of the protrusion part in a 2nd movable mold | type in the recess in a 1st movable mold | type following the process of FIG. Explanatory drawing which shows 3rd Embodiment. The figure which shows the operation state from FIG. Explanatory drawing which shows 4th Embodiment. Explanatory drawing which shows the state at the time of blow molding in 4th Embodiment. Explanatory drawing which shows the state at the time of injection | emission of the foamable resin in 4th Embodiment. Explanatory drawing which shows 5th Embodiment. Explanatory drawing which shows the state at the time of blow molding in 5th Embodiment. Explanatory drawing which shows the state at the time of injection | emission of the foamable resin in 5th Embodiment. Explanatory drawing which shows 6th Embodiment. Explanatory drawing which shows 7th Embodiment. When the leading end of the projecting portion of the second movable mold is previously projected from the inner surface of the bottom wall of the recess of the first movable mold, for example, when the parison is taken into the molding die, the projection of the second movable mold is caused by the core back. Explanatory drawing explaining the state which further retreated the front-end | tip surface of the part rather than the recess bottom wall inner surface in a 1st movable type. When the leading end of the projecting portion of the second movable mold is previously projected from the inner surface of the bottom wall of the recess of the first movable mold, for example, when the parison is taken into the molding die, the projection of the second movable mold is caused by the core back. Explanatory drawing explaining the state which made the part retreat until the front end surface became flush | level with the recess bottom wall inner surface in a 1st movable type. The figure which shows the drooping state of the parison which has a thin part.

Explanation of symbols

1 Molding device 2 Parison (preliminary molded body)
3 Parison Extruder (Preliminary Forming Machine)
4 Mold 7 Resin supply device (melting foamable resin supply means)
21 Fixed type (first type)
21A recess 22 first movable type (second type)
22A Recess 22Aa Recess bottom wall inner surface 22Ac Bottom wall (recess bottom wall)
22B Through-hole 23 Second movable type (third type)
23b Protruding part 23bt Protruding part front end surface (partial region)
27 Cavity 41 Blow Molded Body 41a Recessed Part 45 Molten Solid Resin (molten non-foamable resin)
70 Melt foamable resin

Claims (14)

A tube-shaped preform formed using a melted non-foamable resin is suspended, and the preform is taken into a cavity of a molding die to perform blow molding to form a hollow blow-molded body, The blow-molded product is expanded based on the foaming of the melt-foamable resin by supplying the melt-foamable resin into the blow-molded body in the mold and then increasing the cavity based on the mold operation of the mold. A method of molding a resin molded product,
Before increasing the cavity based on the mold operation of the mold, based on the mold, part of the blow molded body on the side where the cavity is increased is made more than other areas on the same side. Retracted inward of the blow molded body to form a retracted part,
In addition, with the increase in the cavity based on the mold operation of the mold, the retracted portion of a partial region in the blow molded body is expanded.
A method for molding a resin molded product. In claim 1,
After the preform is taken into the cavity of the mold and before the cavity is increased, a part of the preform on the side where the cavity is increased is changed to another on the same side. By being in a state of being retracted inward from the partial region, a state in which a partial region of the blow molded body is retracted to the inward side of the blow molded body from the other region,
A method for molding a resin molded product. In claim 1 or 2,
When the cavity is increased based on the mold operation of the mold, the other region of the blow molded body is maintained in the same state regardless of the mold operation of the mold, while part of the blow molded body Only the region is expanded to the position of the other region of the blow molded body based on the mold operation of the mold.
A method for molding a resin molded product. In claim 1,
The mold includes a first mold, a second mold, and a third mold in series in that order,
The first mold has a recess for forming the cavity, with the opening facing the second and third molds;
The second mold has a recess corresponding to the recess of the first mold in a state in which the opening faces the first mold, and the bottom wall portion of the recess is more than the bottom wall portion of the recess. The reduced through hole is formed so as to penetrate in the arrangement direction of the first, second and third molds,
The third mold has a projecting portion capable of projecting into the recess of the second mold through the through hole of the second mold;
When taking the preform into the cavity of the mold, the second and third molds are moved relative to the first mold,
When the partial area of the blow molded body is retracted to the inner side of the blow molded body than the other area, the protruding portion of the third mold is protruded into the recess of the second mold. The blow molded body is adapted to follow the inner surface of the bottom wall and the protrusion in the recess in the recess,
When the recessed portion of the partial area of the blow molded body is expanded, the protrusion amount of the protruding portion of the third mold in the recess of the second mold expands the recessed area of the partial area of the blow molded body. Less than before
A method for molding a resin molded product. In claim 4,
When the preformed body is taken into the cavity of the mold, the tip end surface of the third mold is positioned so as to be flush with the inner surface of the recess bottom wall of the second mold. Projecting the third mold protrusion into the recess of the second mold before the cavity is expanded into the cavity of the mold.
A method for molding a resin molded product. In claim 4,
The amount of protrusion of the protrusion in the third mold in the recess of the second mold is reduced compared to the case before the expansion portion of the partial area of the blow molded body is expanded. The tip end surface of the protruding portion of the recess is retracted to the inner surface of the bottom wall of the recess.
A method for molding a resin molded product. In any one of Claims 1-6,
Reinforcing fibers are included in the molten foamable resin,
A method for molding a resin molded product. In any one of Claims 1-7,
The melt-foamable resin is obtained by mixing a physical foaming agent in the resin.
A method for molding a resin molded product. In claim 8,
The physical blowing agent is a supercritical fluid;
A method for molding a resin molded product. A preform molding machine that uses a melted non-foamable resin and hangs a tubular preform, and a preform molded by the preform molding machine is taken into a cavity to form the preform. A mold that is molded into a predetermined shape as a hollow blow-molded body, and a melt-foamable resin supply means that feeds a melt-foamable resin into the blow-molded body in the mold. In the molding apparatus set to increase the cavity based on the mold operation when the foamable resin supply means supplies the melt-foamable resin into the blow molded body in the mold,
The mold includes a first mold, a second mold, and a third mold in series in that order,
The first mold has a recess for forming the cavity, with the opening facing the second and third molds;
The second mold has a recess corresponding to the recess of the first mold in a state in which the opening faces the first mold, and the bottom wall portion of the recess is more than the bottom wall portion of the recess. The reduced through hole is formed so as to penetrate in the arrangement direction of the first, second and third molds,
The third mold has a projecting portion capable of projecting into the recess of the second mold through the through hole of the second mold;
The second and third molds are set to move relative to the first mold when the preform is taken into the cavity of the mold;
The protrusion of the third mold protrudes into the recess of the second mold before the cavity is increased based on the mold movement of the mold, and based on the mold movement of the mold. When increasing the cavity, the amount of protrusion of the protrusion into the recess of the second mold is set to be smaller than the state before the cavity is increased.
A molding apparatus characterized by that. In claim 10,
When the protrusion of the third mold takes the preform into the cavity of the mold, the tip end surface of the protrusion of the third mold is flush with the inner surface of the bottom wall of the recess of the second mold. And is set to project into the recess of the second mold after the preform is taken into the cavity of the mold and before the cavity is increased.
A molding apparatus characterized by that. In claim 10 or 11,
The tip end surface of the protrusion of the third mold is positioned so as to be flush with the inner surface of the bottom wall of the recess of the second mold when the cavity is increased based on the mold operation of the mold.
A molding apparatus characterized by that. In any one of Claims 10-12,
The melt-foamable resin supply means is set to supply a mixture of a physical foaming agent in the resin as the melt-foamable resin.
A molding apparatus characterized by that. In claim 13,
The physical blowing agent is a supercritical fluid;
A molding apparatus characterized by that.

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