JP4706446B2 - Foamable resin molding method and mold structure for molding - Google Patents

Description

  The present invention relates to a foamable resin molding method and a mold structure for molding.

  There has been a conventional technique related to a foamed resin molding method in which a foamable resin material is injected into a cavity formed between a pair of molds to form a porous resin molded product (see, for example, Patent Document 1). ). This is because a foamable resin material is supplied into the cavity, and after a predetermined time, the mold is opened by a predetermined amount, and the resin pressure is reduced by lowering the internal pressure of the cavity. Was formed. The molding method will be described in detail based on FIG. As shown in FIG. 13A, the fixed mold 100 and the movable mold 110 are closed to inject the molten foamable resin material into the cavity 120 formed therein. In this state, foaming is not performed because the internal pressure of the resin material in the cavity 120 is higher than the upper limit of the foamable pressure. When the resin material in the cavity 120 elapses for a predetermined time, the surfaces 130, 140, and 150 in contact with the molds 100 and 110 are cooled by the molds 100 and 110, and solidify to form a skin layer, respectively. It remains in the state.

Thereafter, as shown in FIG. 13B, the movable mold 110 is separated (core back) from the fixed mold 100 and the cavity 120 is expanded, whereby the internal pressure of the resin material in the cavity 120 is increased to a pressure at which foaming is possible. Reduce. Thereby, the resin material in the cavity 120 is cooled while foaming, and a resin molded product having a porous interior is formed (shown in FIG. 13C).
JP-A-4-214311 (FIG. 1)

  Here, the resin material in the cavity 120 expands to the left and right in FIG. 13 while being foamed by the core back of the molds 100 and 110, but the surface 150 of the resin material can be extended because it is solidified before foaming. First, as shown in FIG. 13C, the surfaces 130 and 140 are stepped in the vicinity of the surface 150. In particular, when the surfaces 130 and 140 are design surfaces, the appearance is poor, which is a serious problem in the quality of the molded product. This invention is completed based on the above situations, Comprising: It aims at providing the foaming resin molding method and the type | mold structure for shaping | molding which can form a good-looking molded article.

As a means for achieving the above object, the present invention provides a pair of molds provided so as to be openable and closable. The molds are formed on each of the molds, intersect with the opening direction, and face each other. A cavity is formed by a surface and a connecting surface that connects the opposing surfaces to each other when the mold is closed, and a molten foamable resin material is supplied into the cavity, and after a predetermined time, the mold is opened by a predetermined amount. Then, in the foamable resin molding method in which the resin material is foamed by lowering the internal pressure of the cavity to form a porous resin molded product, the length of the connecting surface in the mold opening direction is: the distance between the opposing surfaces of the closed type that put the site where the coupling surface is connected, is formed such that the mold opening amount of length longer than plus when foaming the resin material Specially And the foamed resin molding method according to.

  In the present invention, the connecting surface may be formed on a side surface of a protruding portion that protrudes from the facing surface on one side of the mold and contacts the facing surface on the other side.

  In the present invention, the pair of molds are provided with a pair of protrusions that protrude from the opposing surfaces and abut against each other, and the side surfaces of the protrusions are each tapered. In addition, the connecting surface may be formed on the side surface of the protrusion.

  Further, in the present invention, each of the side surfaces constituting the connection surface of the pair of protrusions is formed so as to be symmetrical with each other in the opening direction of the molding die when the mold is closed. Can be.

Next, in order to solve the above-described problems, the present invention includes a pair of molds provided so as to be openable and closable, and each of the molds intersects with the opening direction and faces each other. A cavity is formed inside the mold by the opposing surface and a connecting surface that connects them to each other when the mold is closed, and one side of the mold has a foaming property melted in the cavity. A resin supply device for supplying a resin material is provided, the resin material is supplied into the cavity, and after a predetermined time, the mold is opened by a predetermined amount to reduce the internal pressure of the cavity. In the molding mold structure for foaming the resin material to form a porous resin molded product, the length of the connecting surface in the mold opening direction is the portion where the connecting surface is connected. that at the time of the closed type The distance between serial facing surfaces, and a mold structure, characterized in that it is formed as the mold opening amount of the length longer than plus when foaming the resin material.

According to the present invention, the length of the connecting surface in the mold opening direction is configured to be longer than the distance between the opposing surfaces at the time of mold closing in the portion where the connecting surface is connected. Therefore, the length of the connecting surface in the mold opening direction can follow the expansion of the resin material due to foaming by an amount longer than the distance between the opposing surfaces, so that the surface of the resin material in contact with the opposing surface is stepped. Generation | occurrence | production can be reduced, it can be set as a flat surface, and it becomes possible to make a molded article with good appearance. Further, since the surface of the expanded resin material is in contact with the opposing surface even during expansion, the surface is shaped according to the shape following the opposing surface, and can be formed more attractively. In addition, since it is not necessary to have a particularly complicated mold structure, a low-cost molding method can be achieved.

Also, the mold opening direction of the length of the connecting surface, at a site connecting surface is connected, the distance between the opposing surfaces at the closed, when the foaming resin material, the length plus the mold opening amount of Then, since the length of the surface of the resin material in contact with the connection surface matches the distance between the opposing surfaces after the resin material has expanded, no stepping occurs on the surface of the resin material, and the connection surface Becomes flat, and it becomes possible to make the molded article more attractive.

The connecting surface protrudes from the facing surface on one side of the mold and is formed on the side surface of the protruding portion that comes into contact with the opposing surface on the other side, so that a through hole can be formed in the molded product by the protruding portion. Generation of a step around the through hole can be reduced.

The pair of molds are provided with a pair of protrusions that protrude from the opposing surfaces and abut against each other, and the side surfaces of the protrusions that are the connecting surfaces are each formed in a tapered shape. Accordingly, the connecting surface can be easily made longer than the distance between the opposing surfaces, and the respective protrusions can be easily removed from the mold.

The length of the connecting surface in the mold opening direction is such that the length of the connecting surface is longer than the distance between the opposing surfaces at the time of closing at the part to which the connecting surface is connected. The length of the opening direction can follow the expansion of the resin material due to foaming by an amount longer than the distance between the opposing surfaces, reducing the occurrence of stepping on the surface of the resin material in contact with the opposing surface. Thus, the mold structure can be formed into a flat surface and capable of forming a molded article having a good appearance.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS. The door trim base material 1 formed by the foamed resin molding method according to the present embodiment is formed of a foam material made of polypropylene, which is a thermoplastic resin, or ABS resin, and the inside thereof is a porous shape including a plurality of bubbles. (Shown in FIG. 2). Although the door trim base material 1 is not shown, the surface is decorated with a skin material or the like, and after a functional product such as a switch is attached, the door trim base material 1 is attached to a door panel of a vehicle door. As shown in FIG. A convex portion serving as an armrest is provided in the central portion of 2, and a peripheral wall 3 is erected on the outer peripheral edge. Further, the board 2 has an opening 4 for attaching a panel (not shown) for fixing a speaker or the like, an attachment hole 5 for fixing an inside handle, and a mounting hole 6 for fitting an ornament member. A plurality of vacuum holes 7 are formed on the substrate 2 so as to be arranged appropriately. The vacuum hole 7 is a through hole having a diameter of about 1 to 2 mm. When a cosmetic skin (not shown) is pasted on the surface of the door trim base material 1, the vacuum hole 7 is added to the back surface (upper surface in FIG. 2) of the door trim base material 1. It plays the role of sucking the epidermis by transferring the vacuum to the surface.

  Next, based on FIG. 3 and FIG. 4, the shaping | molding die 10 which shape | molds the door trim base material 1 is demonstrated. The molding die 10 includes a fixed-side molding die 11 and a movable-side molding die 12 which are a pair of molding dies, and the movable-side molding die 12 is positioned in the vertical direction in FIG. Both can be opened and closed by moving to. At the lower end of the fixed mold 11 that forms the flat portion of the substrate 2 of the door trim base material 1, a facing surface 11 a perpendicular to the moving direction of the movable mold 12 (crossing the opening direction of the molds 11, 12). Is formed and becomes a surface forming the back surface of the substrate 2 of the door trim base material 1. A protrusion 11b is formed on the facing surface 11a, and protrudes downward from the facing surface 11a toward the movable mold 12. The side surface 11c of the protrusion 11b has a so-called taper shape that tapers toward the tip of the protrusion 11b, and the entire protrusion 11b has a truncated cone shape.

  On the other hand, on the upper end of the movable mold 12 that forms the flat portion of the substrate 2 of the door trim base material 1, a facing surface 12 a perpendicular to the moving direction is formed. When the is closed, it faces the facing surface 11a of the fixed mold 11 with a predetermined interval t (shown in FIGS. 4 and 9). The facing surface 12 a is a surface that forms the surface of the substrate 2 of the door trim base 1, and is formed in parallel with the facing surface 11 a of the stationary mold 11 in the present embodiment. Similar to the fixed-side mold 11, a protruding portion 12 b is formed on the facing surface 12 a. The protrusion 12b protrudes upward from the facing surface 12a toward the fixed-side mold 11. The protruding portion 12b has the same size and shape as the protruding portion 11b of the fixed mold 11, the side surface 12c is tapered, and the entire protruding portion 12b has a truncated cone shape.

  As shown in FIG. 4, the pair of protrusions 11 b and 12 b formed on both molds 11 and 12 abut each other at the tip when the molds 11 and 12 are closed, 12c connects the opposing surfaces 11a and 12a to each other and corresponds to the connecting surface according to the present invention. Opposing surfaces 11a and 12a and side surfaces 11c and 12c formed on the molds 11 and 12 form a cavity CV into which the foamed resin material is injected. As shown in an enlarged view in FIG. 9, the lengths of the side surfaces 11c and 12c of both protrusions 11b and 12b in the mold opening direction are both A, and the sum 2A of both closes the molds 11 and 12. In this case, the distance is longer than the distance t in the moving direction of the movable mold 12 between the opposing surfaces 11a and 12a.

  Unlike this embodiment, when the opposing surfaces 11a and 12a are not parallel to each other, or when the opposing surfaces 11a and 12a are not perpendicular to the moving direction of the movable mold 12, the sum 2A of the lengths of the side surfaces 11c and 12c is set to 2A. What is necessary is just to make it longer than the distance of the moving direction of the movable side shaping | molding die 12 between the opposing surfaces 11a and 12a in the site | part which the side surfaces 11c and 12c are connecting, respectively. Further, in order to form the above-described peripheral wall 3 at the peripheral portion of the cavity CV, the fixed-side mold 11 is formed with an inner wall 11d extending in the vertical direction and a horizontal wall 11e so as to close the upper end thereof, and is movable. An outer wall 12d is formed on the side mold 12 so as to face the inner wall 11d in the radial direction.

  An injection device 13 (corresponding to the resin supply device of the present invention) for injecting a molten foamable resin material into the cavity CV is attached to the upper end portion of the fixed mold 11. The injection device 13 abuts the fixed side mold 11 at the nozzle 13a at the lower end, and the resin path 11f for guiding the molten resin injected from the nozzle 13a into the cavity CV is vertically arranged in the fixed side mold 11. It penetrates in the direction. The movable mold 12 includes an electric motor and a speed reducer, and is connected to a mold moving device (not shown) for moving the movable mold 12 up and down.

  Next, based on FIG. 3 thru | or FIG. 10, the shaping | molding method of the door trim base material 1 using the shaping | molding die 10 is demonstrated. From the state in which the molds 11 and 12 shown in FIG. 3 are opened (open mold state), the movable mold 12 is moved upward by the operation of the mold moving device, and the molds 11 and 12 are closed. A state (closed mold state) is set, and a cavity CV is formed therein (shown in FIG. 4). In this state, the foamable resin material that is heated and melted is injected from the nozzle 13a of the injection device 13 and filled into the cavity CV through the resin passage 11f (shown in FIG. 5). The foamable resin material is obtained by mixing a foaming agent with the above-described thermoplastic resin material such as polypropylene. In this state, foaming is not performed because the resin pressure in the cavity CV (internal pressure in the cavity CV) is equal to or higher than the upper limit of the pressure at which the foaming agent foams. However, the surface of the resin material in the cavity CV is cooled and solidified by contacting the opposing surfaces 11a and 12a of the molds 11 and 12, the side surfaces 11c and 12c of the protrusions 11b and 12b, etc., and the skin layer SK (FIG. 9 (shown in FIG. 6 and FIG. 9).

  After a predetermined time has elapsed, the movable side mold 12 is moved downward by a predetermined amount α by the operation of the mold moving device, and the molds 11 and 12 are slightly opened (hereinafter referred to as a core back state). Then, since the cavity CV expands, the resin pressure in the cavity CV decreases, so that the contained foaming agent starts to foam and the resin material expands. Thereby, among the resin materials, the skin layers SK in contact with the opposing surfaces 11a and 12a are separated from each other in the vertical direction while maintaining a flat surface following the shape of the opposing surfaces 11a and 12a. The interval between 12a is t + α (shown in FIGS. 7 and 10). The sum 2A of the lengths of the skin layers SK in contact with the side surfaces 11c and 12c of the protrusions 11b and 12b (which are the same as the lengths of the side surfaces 11c and 12c, respectively) Since the movable mold 12 is formed longer than the distance t in the moving direction, the surface of the skin layer SK in contact with the opposing surfaces 11a and 12a is stepped without hindering the expansion of the resin material. There is nothing.

  Due to the expansion of the resin material, the skin layer SK in contact with the side surfaces 11c and 12c is pulled in the vertical direction in FIG. 9 and eventually becomes a straight line in the same direction, and the vacuum hole 7 surrounding the projections 11b and 12b. Is formed. Here, the sum 2A of the lengths of the skin layers SK in contact with the side surfaces 11c and 12c is the distance t + α between the opposing surfaces 11a and 12a in the core back state (the distance t between the opposing surfaces 11a and 12a at the time of mold closing). , The length of the skin layer SK in contact with the side surfaces 11c and 12c is the length after expansion of the resin material. Since the distance coincides with the distance between the opposing surfaces 11a and 12a, no stepping occurs on the surface of the skin layer SK in contact with the opposing surfaces 11a and 12a, and the inner peripheral surface of the vacuum hole 7 is also formed flat. After that, when the resin material in the cavity CV is cooled and the interior of the door trim base 1 having a porous shape is formed, the movable mold 12 is moved further downward to open the molds 11 and 12. (FIG. 8 shows) and the molded door trim base material 1 is taken out.

  According to the present embodiment, the sum 2A of the lengths in the mold opening direction of the side surfaces 11c and 12c of the protrusions 11b and 12b is formed to be longer than the distance t between the opposed surfaces 11a and 12a when the mold is closed. Therefore, it is possible to follow the expansion of the resin material due to foaming by an amount longer than the distance t between the opposing surfaces 11a and 12a in the sum 2A of the lengths of the side surfaces 11c and 12c in the mold opening direction. It is possible to reduce the occurrence of stepping on the surface of the resin material in contact with the surfaces 11a and 12a, to obtain a flat surface, and to obtain a molded product having a good appearance. In addition, since the surface of the expanded resin material is in contact with the opposing surfaces 11a and 12a even during expansion, the surface is formed flat according to the shape following the opposing surfaces 11a and 12a, and can be formed more attractively.

  Further, the length 2A in the mold opening direction of the side surfaces 11c and 12c is the mold opening amount in the core back state when the resin material is foamed at the distance t in the mold opening direction between the opposing surfaces 11a and 12a when the mold is closed. By adopting a configuration in which α is added, the length 2A of the surface of the resin material in contact with the side surfaces 11c and 12c matches the distance t + α between the opposing surfaces 11a and 12a after the resin material expands. Therefore, no stepping occurs on the surface of the resin material, and the inner peripheral surface of the vacuum hole 7 becomes flat, so that it is possible to obtain a molded product having a better appearance. Further, the protrusions 11b and 12b protrude from both the molds 11 and 12, respectively, and are provided in a pair so as to contact each other. The side surfaces 11c and 12c of the protrusions 11b and 12b, which are connecting surfaces, By adopting a configuration in which each is tapered, the connecting surface can be easily made longer than the distance between the opposing surfaces 11a and 12a, and the respective protrusions 11b and 12b can be easily removed from the mold.

<Embodiment 2>
A second embodiment of the present invention will be described with reference to FIG. In the present embodiment, as in the first embodiment, the protruding portions 21b and 22b protrude from the opposing surfaces 21a and 22a of the pair of molds 21 and 22 toward the other side, respectively. When the mold is closed, the protrusions 21b and 22b are in contact with each other. The side surfaces 21c and 22c of the protruding portions 21b and 22b are formed by arcs that are continuous with each other, and therefore the surface of the cavity CV formed by the side surfaces 21c and 22c has a smooth curve. Also in this embodiment, the sum of the lengths of the side surfaces 21c and 22c in the mold opening direction is formed to be longer than the distance between the opposing surfaces 21a and 22a at the time of mold closing. Since other configurations and molding methods in the present embodiment are the same as those in the first embodiment, description thereof will be omitted.

<Embodiment 3>
A third embodiment of the present invention will be described with reference to FIG. Also in the present embodiment, as in the first embodiment, the protruding portions 31b and 32b protrude from the opposing surfaces 31a and 32a of the pair of molds 31 and 32 toward the other side, respectively. When the mold is closed, the protrusions 31b and 32b are in contact with each other. Since the side surfaces 31c and 32c of the protrusions 31b and 32b are continuous with each other, the surface of the formed cavity CV has a trapezoidal shape. Also in this embodiment, it goes without saying that the sum of the lengths of the side surfaces 31c and 32c in the mold opening direction is longer than the distance between the opposing surfaces 31a and 32a when the mold is closed. Since other configurations and molding methods in the present embodiment are the same as those in the first embodiment, description thereof will be omitted.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.
(1) The present invention can be applied not only to the periphery of the through hole of the molded product but also to the end of the molded product.
(2) The opposing surfaces formed on the pair of molds may not be parallel to each other. Alternatively, the facing surface may not be perpendicular to the mold opening direction. In this case, the length of the connecting surface in the mold opening direction may be formed so as to be longer than the distance in the mold opening direction between the opposing surfaces at the time of mold closing at the portion where the connecting surface is connected.
(3) The protruding portion having a tapered side surface may be protruded only from the opposing surface of one mold, and the tip thereof may be brought into contact with the opposing surface of the counterpart mold when the mold is closed, and the side surface of the protruding portion may be used as a connecting surface.

It is a front view of the door trim base material shape | molded by this invention. It is sectional drawing of the door trim base material shown in FIG. It is a partial cross section figure which shows the open mold state which lowered | hung the movable mold before shaping | molding of the shaping | molding die by Embodiment 1. FIG. FIG. 4 is a partial cross-sectional view of the molding die shown in FIG. 3 before the foaming resin material is injected with the molding die in a closed state. FIG. 4 is a partial cross-sectional view showing a foamed resin material injected in the molding die shown in FIG. 3. FIG. 4 is a partial cross-sectional view showing the surface of the foamable resin material solidified in the molding die shown in FIG. 3. FIG. 4 is a partial cross-sectional view showing a foamed resin material foamed in the molding die shown in FIG. 3. FIG. 4 is a partial cross-sectional view showing an opened state in which a movable mold is lowered in order to take out a molded product in the mold shown in FIG. 3. It is a principal part enlarged view of FIG. It is a principal part enlarged view of FIG. FIG. 6 is an enlarged cross-sectional view of a main part showing a molding state by a molding die according to Embodiment 2. FIG. 6 is an enlarged cross-sectional view of a main part showing a molding state by a molding die according to Embodiment 3. It is sectional drawing which shows the state which injected the resin material fuse | melted in the cavity in the foaming resin molding method by a prior art. It is sectional drawing which shows the state which made the resin material shown to FIG. 13A foam. It is sectional drawing which shows the state which the molded article was completed in the shaping | molding die shown to FIG. 13A.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Door trim base material 10 ... Molding die 11, 21, 31 ... Fixed side shaping | molding die 11a, 12a, 21a, 22a, 31a, 32a ... Opposite surface 11b, 12b, 21b, 22b, 31b, 32b ... Projection part 11c, 12c, 21c, 22c, 31c, 32c ... side surface 12, 22, 32 ... movable side mold 13 ... injection device CV ... cavity A ... length of side surface of protrusion t ... distance between opposing surfaces when closed mold α ... Mold opening when foaming resin material

Claims (5)

In a pair of molding dies provided so as to be openable and closable, formed on each of the molding dies, intersecting the opening direction of the molding dies and facing each other and a coupling surface connecting the opposing surfaces to each other when the mold is closed A cavity is formed in the cavity, a foamable resin material melted in the cavity is supplied, and after a predetermined time, the mold is opened by a predetermined amount, and the internal pressure of the cavity is lowered to reduce the resin material. In a foamable resin molding method in which a resin molded product having a porous interior is formed.
The length of the die opening direction of the coupling surfaces, the distance between the opposing surfaces at the time put that closed type at a site where the coupling surface is connected, plus the amount of opening the mold when foaming the resin material A foamable resin molding method characterized by being formed so as to be longer than the length . 2. The foamable resin according to claim 1, wherein the connecting surface is formed on a side surface of a protruding portion that protrudes from the facing surface on one side of the mold and contacts the facing surface on the other side. Molding method. The pair of molding dies are provided with a pair of protrusions that protrude from the opposing surfaces and abut against each other, and the side surfaces of the protrusions are each formed in a tapered shape, and the connection surface The foaming resin molding method according to claim 1, wherein the foaming resin is formed on the side surface of the protrusion. Each of the side surfaces constituting the connection surface of the pair of protrusions is formed so as to be symmetrical with each other in the opening direction of the mold when the mold is closed. The foamable resin molding method according to claim 3. A pair of molds provided so as to be openable and closable are provided, and each of the molds has an opposing surface that intersects with the opening direction and opposes each other. A cavity is formed inside the mold by the connecting surface to be connected, and a resin supply device for supplying a foamable resin material melted in the cavity is provided on one side of the mold, The resin material is supplied into the cavity, and after a predetermined time, the mold is opened by a predetermined amount, and the resin material is foamed by reducing the internal pressure of the cavity. In a mold structure for forming a product,
The length of the die opening direction of the coupling surfaces, the distance between the opposing surfaces at the time put that closed type at a site where the coupling surface is connected, plus the amount of opening the mold when foaming the resin material A mold structure for molding, wherein the mold structure is formed to be longer than the length .

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