JP5321083B2 - Molding method and molding apparatus for foamed resin molded product - Google Patents

Description

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

As a method for molding a foamed resin molded product, for example, in Patent Document 1, a melt-foamable resin containing a foaming agent is short-shot (that is, less than the cavity volume) in a cavity formed in a mold. A molding method is disclosed in which the molten foamable resin in the cavity is foamed by supplying (by volume) by injection and moving the mold in the mold opening direction (core back) during the molding.
JP 2004-17285 A

  By the way, when the molten resin is supplied into the cavity by injection, for example, the injection supply is performed through a plurality of gates, a pin or the like is provided in the molding die to form a hollow portion in the molded product, or the shape of the molded product Is complicated, a plurality of flows of the molten resin are merged in the cavity, and a weld portion fused by the merge is generated in the molded resin molded product.

  Here, the inventors of the present application have noticed that when a foamed resin molded product is formed from a melt-foamable resin, the diameter of the foam cell in the weld portion is larger than the diameter of the foam cell in the other portion. The enlargement of the foam cell has a disadvantage that it causes a local strength reduction of the foamed resin molded product.

  This invention is made | formed in view of this point, The place made into the objective is to avoid the local strength fall of a foamed resin molded product.

  As a result of investigation by the present inventors, the enlargement of the foam cell in the weld portion is that the pressure is relatively low at the flow front of the melt-foamable resin flowing in the cavity, and the foaming agent in the melt-foamable resin is foamed. It has been found that it is caused by the ease of doing this. That is, in the middle of flowing in the cavity, foaming of the foaming agent is started at the flow front part, and in the vicinity of the weld generating part where the flow front parts collide with each other, compared with the surrounding part, There will be a large growing blowing agent. When the core back of the mold is performed in this state, the foaming agent that has grown relatively large in the weld generating part has priority over the foaming agent present in the surrounding part, and other foams dissolved in the resin. As a result, in the weld generating part, the foaming agent grows larger than the foaming agent present around it, which leads to enlargement of the foam cells in the weld part. I found it. Such enlargement of the foam cell becomes particularly remarkable when the melt-foamable resin is supplied into the cavity in a short shot state because the pressure in the cavity becomes relatively low.

  Accordingly, the inventors of the present invention have repeatedly studied focusing on the fact that the core back is divided, and prior to performing the core back in the weld generating portion, the core back is formed in the peripheral portion adjacent to the weld generating portion. The foaming agent dissolved in the resin in the vicinity of the weld generating portion is taken in and consumed during the growth of the foaming agent in the surrounding area. Thus, it has been found that a state where excessive foaming agent is present at the time of starting the core back of the weld generating portion can be avoided. As a result, even if the foaming agent in the weld generating part has already grown greatly at the time when the supply of the melt-foamable resin is completed, it is suppressed from further taking in the foaming agent dissolved during the core back. As a result, enlargement of the foam cell in the weld portion can be suppressed.

  The molding method of the foamed resin molded product includes a supply step of injecting and supplying a melt-foamable resin into the cavity formed in the mold, and increasing the volume of the cavity by moving the mold in the mold opening direction. A foaming step of foaming the melt-foamable resin in the cavity, and a molding step of solidifying the melt-foamable resin and molding a foamed resin molded product after the movement of the molding die is completed. The mold includes a weld generating portion corresponding to a weld portion where a plurality of flows of the melt-foamable resin merged and fused in the foamed resin molded product, and a peripheral portion adjacent to the weld generating portion, Are defined, and the weld generating portion and the peripheral portion of the mold can be moved independently of each other in the mold opening direction. After starting the movement in the mold opening direction of the peripheral portion, after a lapse of a predetermined delay time, and starts moving in the mold opening direction of the welding portion.

  By performing the core back that increases the volume of the cavity by moving the molding die in the mold opening direction, the foamable resin in the cavity is foamed. At the core back, the weld generating portion corresponding to the weld portion is expanded. Start the core back of the adjacent surroundings first. As a result, the foaming agent starts to grow first in the peripheral portion, and the foaming agent in the peripheral portion grows while taking in another foaming agent melted in the resin in the vicinity of the weld generating portion. After a predetermined delay time has elapsed after the start of the core back of the peripheral part, the core back of the weld generating part starts, but at the time of starting the core back of the weld generating part, the foam melted in the resin near the weld generating part Since the agent is consumed to some extent and does not exist excessively, it is avoided that the foaming agent in the weld generating part takes in another foaming agent and grows significantly. As a result, the foaming agent does not grow greatly locally at the weld generating part, and the expansion of the foamed cells in the welded part of the foamed resin molded product is suppressed, and the foamed cells are homogenized.

  The movement of the weld generating part in the mold opening direction may be performed at a speed equal to or higher than the moving speed of the peripheral part in the mold opening direction.

  In the case of foaming by the core back, when the mold opening speed is relatively slow, the foaming agent grows while taking in the surrounding foaming agent, and each foaming agent easily grows to a large size, When the mold opening speed is relatively high, each foaming agent grows without taking in another foaming agent, and the growth size of each foaming agent is prevented from becoming too large. Therefore, the moving speed in the mold opening direction of the weld generating part is set to be equal to or higher than the moving speed in the mold opening direction of the surrounding part, and by making the moving speed relatively fast, enlargement of the foam cells in the weld part is achieved. Further effectively suppressed.

  The supplying step may supply an amount of the melt-foamable resin less than the volume of the cavity into the cavity.

  When supplying a melt-foamable resin in a short shot state, it is possible to easily adjust and set the foaming ratio of the foaming agent, while the pressure in the cavity is relatively low as described above. As a result, the foamed cells tend to enlarge in the weld portion. On the other hand, in the said structure, since the enlargement of the foam cell in a weld part is suppressed, it is especially effective in the shaping | molding method which supplies molten foamable resin in a short shot state.

  A molding apparatus for a foamed resin molded product includes a molding die having a cavity and a supply means for injecting and supplying a melt-foamable resin into the cavity, and the molding die is a foamed resin molded by the molding die. In the molded product, a weld generating portion corresponding to a weld portion fused by fusion of a plurality of flows of the melt-foamable resin and a peripheral portion adjacent to the weld generating portion are respectively defined, and the mold is By moving in the mold opening direction to increase the volume of the cavity, the molten foamable resin in the cavity is configured to foam, and the mold further includes the weld generating portion and the peripheral portion. It is configured to be able to move in the mold opening direction independently from each other, and at the time of movement in the mold opening direction, at least the movement of the peripheral portion has started. , After a predetermined delay time, the movement of the welding portion is configured to start.

  The moving speed of the weld generating part in the mold opening direction may be set to be higher than the moving speed of the peripheral part in the mold opening direction.

  As described above, according to the present invention, at the time of core back, the core back of the peripheral portion adjacent to the weld generating portion is started first, and the peripheral portion is first melted in the resin near the weld generating portion. By growing the foaming agent while incorporating other foaming agents, it is avoided that the foaming agent in the weld generating part grows significantly by incorporating other foaming agent, and locally in the weld generating part. It is possible to prevent the foaming agent from growing greatly. As a result, the enlargement of the foamed cells in the weld portion of the foamed resin molded product can be suppressed, and the local strength reduction of the foamed resin molded product due to the enlargement of the foamed cells can be avoided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

  FIG. 1 shows an example of a molding apparatus 1. The molding apparatus 1 molds a foamed resin molded product by foaming and solidifying the melt-foamable resin 70 supplied into the cavity 27 of the mold 4. The foamed resin molded product can be used for a wide range of applications such as for automobiles, building materials, household appliances, daily goods, etc. In each application, the foamed resin molded products are reinforcing materials, heat insulating materials, sound insulation materials. It can be used as a vibration proofing material, a shock absorbing material or the like. FIG. 2 shows a duct member 50 of an automotive air conditioner as an example of such a foamed resin molded product. The duct member 50 is halved, and a pair of duct members 50 are brought into contact with each other to form a tubular duct as a whole. Constructing such an air conditioning duct with a foamed resin molded article is advantageous in that high heat insulation is obtained because the pipe wall of the duct is composed of a heat insulating layer made of foamed cells.

  The duct member (foamed resin molded product) 50 will be described in more detail. The foamed resin molded product 50 has a hollow bulge that swells in a semicircular shape extending in the length direction perpendicular to the width direction at the center in the width direction (from the left hand to the right back in FIG. 2). And a flat plate portion 52, 52 extending along the bulging portion 51 and extending outward from both side edges in the width direction of the bulging portion 51. The flat plate portion 52 is formed with a plurality of through-holes 54 at appropriate positions that penetrate in the thickness direction and are used for mounting and fixing the foamed resin molded product 50. When the foamed resin molded product 50 that is relatively elongated in the length direction is molded as described above, the melt-foamable resin 70 is supplied into the cavity 27 from a plurality of locations (gates) at intervals in the length direction. There is a case. Reference numeral 27a in FIG. 2 virtually shows an example of the gate position. When the molten foamable resin is injected into the cavity 27 from each of the plural (here, two) gates 27a, the molten foamable resin flowing from the two gates 27a is between the gates 27a. The welds 55 join at substantially the middle position (see the dashed-dotted arrow in FIG. 2), and the welded portion 55 is fused to the foamed resin molded product 50 due to such joining. In addition, each through hole 54 of the flat plate portion 52 is formed by providing a pin in the mold 4, and the melt-foamable resin that flows around the both sides of the pin also in the vicinity of the through hole 54. Are joined and fused (see the dashed line arrow in FIG. 2), the weld portion 55 is generated. In the foamed resin molded product 50 using the melt-foamable resin, the foam cell tends to be enlarged in the weld portion 55, which may cause a local strength reduction of the foamed resin molded product 50. In particular, since the through-hole 54 is used for mounting and fixing, a relatively large load acts in the vicinity thereof, so it is important to ensure the necessary strength. The molding device 1 and the molding method disclosed herein can avoid such a local strength reduction of the foamed resin molded product 50.

  As shown in FIG. 1, the molding apparatus 1 includes a molding die 4 and a resin supply device 7 (supplying unit) that supplies a melt-foamable resin 70 into the cavity 27 of the molding die 4. The mold 4 shown here is drawn with a simplified shape for easy understanding, and does not correspond to the shape of the foamed resin molded product 50 shown in FIG.

  The molding die 4 includes a fixed die 21 and a movable die 22 that slides in a horizontal direction (left and right direction in FIG. 1) relative to the fixed die 21 to perform mold closing and mold opening. ing. A concave portion 21 a is formed on the surface of the fixed die 21 on the movable die 22 side, and the side surface constituting the concave portion 21 a constitutes a cavity surface 27 b that defines the cavity 27. On the other hand, the movable mold 22 is configured to approach and separate from the fixed mold 21 by a drive mechanism (not shown). The movable mold 22 also has, on the surface on the fixed mold 21 side, a convex portion 22a that protrudes into the fixed mold 21 side and is fitted into the concave portion 21a, and the side surface constituting the convex portion 22a is A cavity surface 27b that defines the cavity 27 is formed. Although not shown, the mold 4 is also provided with a cooling means for cooling the melt-foamable resin 70 filled in the cavity 27. The cooling means is constituted by, for example, a coolant channel disposed in the mold 4.

  When the mold 4 is closed, although illustration is omitted, the movable mold 22 moves to the fixed mold 21 side, and the convex portion 22a is fitted into the concave portion 21a, thereby completing the mold closing. As a result, the cavity 27 is partitioned and formed in the mold 4 by the concave portion 21a and the convex portion 22a. Further, when the mold 4 is core-backed as described later, the movable mold 22 moves to the opposite side of the fixed mold 21 while maintaining the state where the convex portion 22a is fitted in the concave portion 21a. . Although details will be described later, the movable mold 22 has a divided structure, and is configured such that a core back can be performed independently for each divided portion. Furthermore, when the mold is opened after the molding is completed, the movable mold 22 moves greatly to the side opposite to the fixed mold 21 until the convex portion 22a fitted in the concave portion 21a is removed from the concave portion 21a. Thereby, the resin molded product molded in the cavity 27 can be taken out.

  The resin supply device 7 includes an injection molding machine 5 that injects the melt-foamable resin 70 and a resin that is provided in the fixed mold 21 and that guides the melt-foamable resin 70 injected from the injection molding machine 5 into the cavity 27. And an introduction passage 6.

  The injection molding machine 5 has a cylindrical injection cylinder 41. A nozzle 41 a is provided at the front end of the injection cylinder 41, and the nozzle 41 a is connected to the resin introduction passage 6. Inside the injection cylinder 41, a screw 42 is rotatably provided and can be advanced and retracted. A drive mechanism (not shown) for driving the screw 42 is provided on the rear end side of the screw 42.

  A hopper 43 for charging resin pellets 71 is connected to an upper portion of the rear end portion of the injection cylinder 41, and the resin pellets 71 charged into the hopper 43 are supplied into the injection cylinder 41. A plurality of heaters (not shown) are installed on the peripheral wall of the injection cylinder 41 so as to be arranged in the front-rear direction of the injection cylinder 41. The resin pellets 71 supplied from the hopper 43 into the injection cylinder 41 are melted by the heater while moving to the front side of the injection cylinder 41 by the rotation of the screw 42 by the drive mechanism.

  An injection nozzle 45 for injecting a supercritical fluid into the injection cylinder 41 is connected to an intermediate portion in the front-rear direction of the injection cylinder 41. The injection nozzle 45 is connected to a supercritical fluid supply device 46 that supplies a gas such as nitrogen or carbon dioxide as a supercritical fluid (a state exceeding the critical pressure and critical temperature). The supercritical fluid is injected into the injection cylinder 41 from the injection nozzle 45 by the device 46. As a result, the supercritical fluid is mixed and dissolved in the molten resin obtained by melting the resin pellets 71 to form the molten foamable resin 70. The supercritical fluid is vaporized at the time of molding, so that the molten foamable resin 70 is foamed. Will do. That is, in the present embodiment, the supercritical fluid is used as a foaming agent in order to perform ultrafine foam molding using the properties of the supercritical fluid, that is, the properties having both the viscosity and dissolving power as a liquid and intense molecular motion as a gas. A physical foaming agent consisting of The resin pellet 71 is made of, for example, polypropylene, polyethylene, polystyrene, or the like.

  The melt-foamable resin 70 is pushed out to the front portion of the screw 42 in the injection cylinder 41 by the rotation of the screw 42. At this time, the screw 42 is retracted by the pressure, and only a predetermined distance (a distance such that the amount of the melt-foamable resin 70 necessary for one injection is accommodated in the front portion of the screw 42 in the injection cylinder 41). When retreating, the screw 42 stops rotating. Thus, the melt-foamable resin 70 supplied into the cavity 27 of the mold 4 is accommodated in the front portion of the screw 42 in the injection cylinder 41. When the molten foamable resin 70 is injected, the screw 3 is advanced at high speed by the drive mechanism. As a result, the melt-foamable resin 70 is supplied from the nozzle 41 a through the resin introduction passage 6 into the cavity 27 of the mold 4.

  The resin introduction passage 6 opens on the surface of the fixed mold 21 opposite to the movable mold 22, communicates with the injection molding machine 5, and divides into two in the middle of the resin introduction passage 6 to the side surface of the recess 21 a in the fixed mold 21. In (the cavity surface 27b extending in the up-down direction), the openings are opened at intervals in the up-down direction. The opening in the cavity surface 27b of the recess 21a constitutes the gate 27a. As described above, in this mold 4, two upper and lower gates 27 a are set in FIG. 1, and illustration is omitted, but the molten foamable resin flows radially from each gate 27 a, thereby causing the cavity 28 to flow. The molten foamable resin 70 is substantially filled therein. At this time, the melt-foamable resin 70 that flows substantially downward from the upper gate 27a and the melt-foamable resin 70 that flows substantially upward from the lower gate 27a merge at a substantially intermediate position between the two gates 27a ( Collision), and the fusion resin molded product may be welded. In the following description, the part of the mold 4 corresponding to the weld part of the foamed resin molded product may be referred to as a weld generating part, and the part of the mold 4 adjacent to the weld generating part may be referred to as a peripheral part.

  Thus, the movable mold 22 in the molding die 4 is divided into a weld generating part 23 and a main body part 24 (including a peripheral part) other than the weld generating part. 23 and the main body 24 are configured to be able to move in the mold opening direction independently of each other (see arrows in FIG. 1). Thus, the weld generating part 23 and the main body part 24 can be configured such that the start timing of the core back can be made different from each other, and the mold opening speed (moving speed) can also be made different from each other. Has been. In the molding die 4 schematically shown in FIG. 1, only one weld generating portion 23 is set. However, if a plurality of weld generating portions 23 are set in the molding die 4, each of them is set. The weld generating part 23 may be separated from the main body part 24.

  Next, a method of molding a resin molded product using the molding apparatus 1 will be described with reference to the timing chart of FIG. As shown in FIG. 3, after the molded product molded in the previous molding cycle is taken out from the mold that has been opened, the movable mold 22 is slid to start closing the mold 4. Thus, the mold 4 is closed as shown in FIG.

  After the mold closing of the mold 4 is completed, the screw 42 of the injection molding machine 5 is advanced at a high speed, and the molten foamable resin 70 accommodated in the front portion of the screw 42 in the injection cylinder 41 is injected. As a result, the high-pressure molten foamable resin 70 is supplied into the cavity 27 of the mold 4 through the two gates 27a. Here, the supply amount of the melt-foamable resin 70 is set to be smaller than the volume of the cavity 27, whereby the inside of the cavity 27 is in a so-called short shot state. Supplying the melt-foamable resin 70 in such a short shot state is advantageous in controlling the expansion ratio of the resin molded product.

  The melt-foamable resin 70 supplied into the cavity 27 flows in the cavity 27 and collides with each other in the weld generating portion 23 as shown by P1 in FIG. At this time, the weld generating portion 23 is relatively large due to the fact that foaming of the foaming agent is started at the flow front end while the melt-foamable resin 70 is flowing in the cavity. The grown blowing agent is present (P2 in FIG. 4).

  After completion of the injection supply of the melt-foamable resin 70, after a predetermined delay time has elapsed, the core back for opening the mold 4 in the mold opening direction is started. The molten foamable resin 70 is foamed while increasing the volume of the cavity 27.

  Here, for example, as shown in FIG. 5 (a) or (b), the core back starts the core back of the main body 24 first, and then after a predetermined delay time has elapsed, the core of the weld generator 23 Start back. By core-backing the peripheral portion before the weld generating portion 23, the foaming agent there begins to grow before the foaming agent in the weld generating portion 23, as shown in P3 of FIG. The foaming agent that has started growing grows while taking in another foaming agent in the vicinity of the weld generating portion 23 (see the arrow in P3). As a result, excess foaming agent in the weld generating portion 23 is eliminated.

  Slowly thereafter, by starting the core back of the weld generating portion 23, the foaming agent of the weld generating portion 23 has already grown greatly at the time when the supply of the melt-foamable resin 70 is completed, but takes in extra foaming properties. It will not grow much larger than that. As a result, each foaming agent does not grow too much locally in the weld generating portion 23, and is homogenized as schematically shown at P4 in FIG.

  Here, the moving speeds of the weld generating part 23 and the main body part 24 may be set to the same speed as shown in FIG. In contrast to this, as shown in FIG. 5B, the moving speed of the weld generating portion 23 may be made faster than the moving speed of the main body portion 24. 5A and 5B respectively show the relationship between the position (vertical axis) with respect to time (horizontal axis) with respect to time (horizontal axis) with the mold closed state as the origin for the weld generating part 23 and the main body part 24. The inclination corresponds to the moving speed of the weld generating part 23 and the main body part 24. When the melt-foamable resin 70 is foamed by the core back, when the mold opening speed is relatively slow, the foaming agent grows while taking in the surrounding foaming agent, and each foaming agent grows to a large size. On the other hand, when the mold opening speed is relatively fast, each foaming agent grows without taking in other foaming agents, and the growth size of each foaming agent is prevented from becoming too large. It has the characteristic that Therefore, as shown in FIG. 5B, when the moving speed of the weld generating portion 23 is set to a relatively high speed, the growth of the foaming agent is suppressed and the expansion of the foamed cells in the weld portion is more effective. There is an advantage that it can be suppressed.

  Further, the predetermined delay time is preferably set so that the foaming agent in the surrounding area can secure a time that allows the foaming agent to grow while taking in other foaming agents in the vicinity of the weld generating part. On the other hand, it is difficult to significantly delay the completion timing of the core back, in order to avoid solidification and no longer foaming as the temperature of the melt-foamable resin 70 decreases. In this regard, setting the moving speed of the weld generating portion 23 to a relatively high speed sets the delay time related to the start timing of the core back relatively long without significantly delaying the completion timing of the core back. This is also advantageous.

  Note that the amount of movement of the movable mold 22 is determined in advance depending on how much the diameter of the foam cell is to be set, and such core back is effective in controlling the foaming magnification.

  The resin temperature of the melt-foamable resin 70 decreases from the start of supply into the cavity 27, and solidifies (cures) when the resin temperature reaches the solidification temperature (the core back is completed when the solidification temperature is reached). Later). When the melt-foamable resin 70 is solidified in this way, foaming stops and the foamed cell diameter does not increase any further.

  After completion of the core back, it waits for a predetermined time to elapse as shown in the timing chart of FIG. During this time, the melt-foamable resin 70 is completely solidified. Thus, the molding of the foamed resin molded product using the melt-foamable resin 70 is completed. Thereafter, the movable mold 22 is moved to the side opposite to the fixed mold 21 to open the mold, and the molded foamed resin molded product is obtained. Remove from the mold 4. Then, unnecessary portions of the foamed resin molded product are cut to complete the foamed resin molded product.

  As described above, in this molding apparatus 1, by dividing the movable die 22 into the weld generating part 23 and the main body part 24, the start timing of the core back in each part 23, 24 can be made different from each other. Thus, the start timing of the core back of the weld generating part 23 is delayed from the surrounding part. As a result, as described above, the foaming agent in the vicinity of the weld generating portion is consumed first by the growth of the foaming agent in the peripheral portion, and the growth is performed by taking in other foaming agents by growing in advance. It is suppressed that the foaming agent of the weld generating part 23 which is easy to grow grows greatly by the core back. Thus, enlargement of the foam core at the weld portion of the foamed resin molded product is suppressed, and as a result, local strength reduction of the foamed resin molded product can be avoided.

  In particular, when the melt-foamable resin 70 is supplied into the cavity 27 in a short shot state, the foam core tends to be enlarged at the weld portion. The advantage that the expansion ratio can be easily controlled by supplying the melt-foamable resin 70 by a shot or by the core back is particularly effective. The supply of the melt-foamable resin 70 by short shot is not essential and can be omitted as appropriate.

  The technology disclosed here is not limited to molding using a physical foaming agent, but can also be applied to molding using a chemical foaming agent.

  As described above, the present invention is useful as a molding apparatus and a molding method for a foamed resin molded product because a local strength reduction of the foamed resin molded product can be avoided.

It is the schematic of a shaping | molding apparatus. It is a perspective explanatory view showing an example of a foamed resin molded product. It is a timing chart which shows the shaping | molding procedure of a foamed resin molded product. It is explanatory drawing which shows typically the state of the weld generation | occurrence | production part vicinity at the time of shaping | molding. It is a figure which shows the delay time of the movement start timing between a weld generation part and a main-body part, and relative moving speed relationship.

DESCRIPTION OF SYMBOLS 1 Molding device 23 Weld generating part 24 Body part (surrounding part)
27 Cavity 4 Mold 7 Resin supply device (supply means)
70 Melt foamable resin

Claims (5)

A supply step of injecting and supplying a melt-foamable resin into a cavity defined in the mold;
A foaming step of foaming the melt-foamable resin in the cavity by moving the mold in the mold opening direction to increase the volume of the cavity;
A molding step of solidifying the melt-foamable resin and molding a foamed resin molded product after the movement of the mold is completed,
The molding die includes a weld generating portion corresponding to a weld portion where a plurality of flows of the melt-foamable resin merged and fused in the foamed resin molded product, and a peripheral portion adjacent to the weld generating portion. Each is defined, and the weld generating part and the peripheral part of the mold can move in the mold opening direction independently of each other,
In the foaming step, a method for molding a foamed resin molded product, wherein at least a movement of the peripheral portion in the mold opening direction is started and then a movement of the weld generating portion in the mold opening direction is started after a lapse of a predetermined delay time. The molding method according to claim 1,
The method of molding a foamed resin molded product, wherein the movement of the weld generating part in the mold opening direction is performed at a speed equal to or higher than the moving speed of the peripheral part in the mold opening direction. In the molding method according to claim 1 or 2,
The supplying step is a molding method of a foamed resin molded product in which an amount of the molten foamable resin smaller than the volume of the cavity is supplied into the cavity. A mold having a cavity;
A supply means for injecting and supplying the melt-foamable resin into the cavity,
The mold includes a weld generating portion corresponding to a weld portion in which a plurality of flows of the melt-foamable resin are merged and fused in a foamed resin molded product molded by the mold, and adjacent to the weld generating portion. And the surrounding area to be defined,
The mold is configured to foam the melt-foamable resin in the cavity by moving in the mold opening direction and increasing the volume of the cavity.
The mold is further configured so that the weld generating portion and the peripheral portion can move in the mold opening direction independently of each other, and at least when the movement in the mold opening direction is performed, A molding apparatus for a foamed resin molded product, configured to start the movement of the weld generating portion after a predetermined delay time has elapsed after the movement of the surrounding portion has started. The molding apparatus according to claim 4, wherein
The apparatus for molding a foamed resin molded product, wherein a moving speed of the weld generating part in the mold opening direction is set to be higher than a moving speed of the peripheral part in the mold opening direction.

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