JP6245215B2 - Mold for molding beaded synthetic resin and method for producing foamed synthetic resin beaded product - Google Patents

Description

  The present invention relates to a mold for molding a bead-method foamed synthetic resin used for a heat insulating container, a packaging material, and the like, and a bead-method foamed synthetic resin-molded product that uses the mold to produce a molded product of the foam synthetic resin. Regarding the method.

In the bead method foam synthetic resin molding, thermoplastic resin foam beads are filled into a molding space (cavity) formed by a pair of molds consisting of a core mold (convex mold) and a cavity mold (concave mold). It is heated and fused with steam, cooled and dried to obtain a molded product having a required shape.
The pair of molds for molding a beaded synthetic resin is a mold for molding the inside and outside of the mold in order to supply steam from outside into the molding space and to discharge steam from inside the molding space. Since there are required steam holes communicating with each other, a large number of vent holes (core vent mounting holes) are formed in a direction perpendicular to the mold surface, and the outer diameter is, for example, 10 mm and the total length (height). A core vent (vent fitting) having a 6 mm cap shape and a large number of slits or small holes formed thereon is generally used so that the mold surface (molding surface) side is flush.

The structure of such a beaded foam synthetic resin molding die is likely to cause a decrease in strength, for example, by forming a large number of vent holes with a diameter of 10 mm, and the die is deformed by driving the core vent into the vent hole with a hammer or the like. And the mold may be damaged, drilling work to form a large number of vent holes in the mold, driving work for hammering core vents into a large number of vent holes, and the mold surface (molding surface) Since the polishing operation for smoothing takes time, the manufacturing cost increases, and particularly noise is caused during the driving operation, which leads to deterioration of the working environment.
In addition, when molding a molded product such as a heat-insulated container having a relatively large thickness and a large capacity, not a planar shape, in a pair of molds forming a molding space of the molded product shape. In order to heat and fuse the filled foam beads with a large capacity, it is necessary to increase the steam hole opening ratio so that a large amount of steam can be efficiently supplied into the molding space. This increases the above problem.
Furthermore, when the corner (corner) shape of the molded product is a curved surface, the mold surface (molding surface) is formed so that the corner R (corner R), which is a curved portion, is formed in the molded product. It is necessary to form a corner R portion (corner R portion) which is a curved surface portion. However, when a vent hole is formed in the corner R portion (corner R portion) which is a curved surface portion of the mold and the core vent is driven in, the end surface of the core vent is flat, so the corner R portion (corner) of the mold is Since the (R portion) is not flush with each other, the core vent cannot be disposed at the corner R portion (corner R portion) which is a curved portion of the mold.

In addition, as in Patent Document 1, the inner diameter of the vent holes 2, 2,... Formed in the bead method foamed synthetic resin molding die is slightly larger than the outer diameter of the vent metal fittings 3, 3,. By forming the peripheral grooves 4, 4,... For accommodating the adhesive in the vent fitting 3, the vent fittings 3, 3,... Are manually inserted into the vent holes 2, 2,. However, there are some which are fixed by a heat-resistant adhesive applied to the outer periphery of the bent metal fittings 3, 3,.
Further, as in Patent Document 2, the cavity side of a pair of molds (concave part 5 and convex part 6) in which circular steam holes 22, 22,... And 23, 23,. The metal plates 33 and 33 having appropriate thicknesses are joined to the surfaces, and the metal plates 33 and 33 are communicated with the steam holes 22, 22,... And 23, 23,. .., And 31, 31,... Are formed in the shape of narrow grooves, lattices, radials, concentric circles, staggered shapes, spirals, or the like.

JP-A-1-301314 JP 2004-230590 A

According to the structure of a bead-method foam synthetic resin molding die as in Patent Document 1, the vent metal fittings 3, 3,... Are attached to the vent holes 2, 2,. Improvements can be made, and since there is no driving work with a hammer or the like, it is possible to reduce the burden of manual labor and improve the working environment by suppressing noise.
However, since it is necessary to use a large number of specially-shaped vent fittings 3, 3,... Having the circumferential grooves 4, 4,.
In addition, while there is no driving operation, it is necessary to perform an operation of applying an adhesive to the circumferential grooves of a large number of vent fittings 3, 3,... It takes time.
In addition, the clearance between the vent hole 2 and the vent fitting 3 is in the range of 0.05 mm to 0.1 mm in consideration of securing the adhesive strength and workability of inserting the vent fittings 3, 3,. Since it is necessary to perform drilling to form the vent holes 2, 2,..., The cost of the drilling increases.
Even if these problems are solved, the problem of strength reduction due to the formation of a large number of vent holes is inevitable.

In addition, according to the structure of a bead-method foamed synthetic resin molding die as in Patent Document 2, a core vent with a large number of slits or small holes is not used, and a fine grid of 0.2 to 0.4 mm such as a lattice shape is used. Since the steam is supplied / discharged from the groove-shaped steam slits 30, 30,..., 31, 31,..., The steam slit marks formed on the surface of the molded product are inconspicuous, and thus have a design surface that gives a high-quality impression. Molded products can be molded.
However, since the vapor slits 30, 30,..., 31, 31,... Formed in the metal plates 33, 33 are formed in a lattice shape or the like, after the vapor slits 30, 30,. Since the metal plates 33 and 33 are not integrated, the metal plates 33 and 33 after forming the steam slits 30, 30,..., 31, 31,. After joining 33 and 33 to the recessed part 5 and the convex part 6, it is necessary to form the vapor | steam slits 30, 30, ..., 31, 31, ... in the metal plates 33,33.
In addition, in order to pass the steam from the concave portion 5 and the convex portion 6 to the vapor slits 30, 30,..., 31, 31,. The holes 22, 22, ... and 23, 23, ... need to be formed.
Therefore, drilling of circular steam holes 22, 22,..., 23, 23,... Into the concave portion 5 and the convex portion 6 of the mold, joining of the metal plate 33 to the concave portion 5, and the metal plate to the convex portion 6. 33, and the metal plates 33, 33 joined to the recesses 5 and 6 need to be processed to form vapor slits 30, 30,..., 31, 31,. The manufacturing cost of the mold increases.

Furthermore, in the conventional general bead method foaming synthetic resin molding die formed by driving the core vent into the vent hole of the die and the bead method foaming synthetic resin molding die of Patent Document 1, for example, the full length ( For the convenience of mounting a core vent with a height of 6 mm, it is necessary to make the thickness of the mold relatively thick. Therefore, the heat capacity of the mold increases, so it takes time for heating and cooling, and the weight of the mold is large. Become.
Furthermore, in any of the conventional general bead-method foamed synthetic resin molding molds and the bead-method foamed synthetic resin molding dies described in Patent Documents 1 and 2, the mold surface (molding surface) is the opposite side. (See, for example, the drawings of Patent Document 1 and FIG. 2B of Patent Document 2), these recesses (for example, Patent Document 2, vapor holes 22, 22,...). And the cooling water sprinkled in the cooling step stays at 23, 23,.
Here, in the cooling process, since the drying process for drying the product is also performed at the same time, if the cooling water stays in the depression, the drying process takes a long time. This is a major cause of longer molding cycles, including the problem of mold supercooling. In the current foam molding, vacuum cooling drying or vacuum cooling drying is performed for the purpose of shortening the cooling / drying process time. It is an obstacle to the realization of time reduction.

  Therefore, in view of the above-mentioned situation, the present invention intends to solve the problem of reducing the manufacturing cost of the mold, shortening the heating and cooling time and reducing the weight of the mold, beautifying the surface property of the molded product, and cooling / drying. The object is to provide a bead-method foamed synthetic resin molding die capable of shortening the process time.

  As a result of intensive studies to solve the above problems, the present inventor has completed the present invention.

That is, the gist of the present invention is as follows.
[1] Filling a molding space formed by a pair of molds consisting of a core mold and a cavity mold with foam beads of thermoplastic resin, heating and fusing the foam beads with steam, cooling and drying, as required The mold used for molding a foam synthetic resin with a bead method to obtain a molded product of foam synthetic resin,
A slit-like steam hole directly formed in the mold itself for allowing the steam to communicate with the inside and outside of the mold through a required portion of the three-dimensional mold formed by cutting and / or casting. I have a,
A beaded foam synthetic resin molding die, wherein the slit-shaped vapor hole is formed from a metal saw attached to a main shaft of a horizontal machining center .
[2] of the slit-shaped steam holes, one provided in the mounting flange portion of the mold, beads method foamed synthetic resin molding mold according to the which is open to the outside (1) .
[ 3 ] The bead-method foamed synthetic resin molding die according to [1] or [2] , wherein the slit-shaped vapor hole is provided at least on a curved portion of the die.
[ 4 ] The bead-method foam synthetic resin molding die according to [1] or [2] , wherein the slit-shaped vapor hole is provided along a surface shape changing portion of the die.
[ 5 ] The beaded foam synthetic resin molding die according to [1], wherein the slit-shaped vapor holes arranged on a side surface of the die are provided along an opening / closing direction of the die.
[6] The bead-method foamed synthetic resin molding die according to any one of [1] to [5] , wherein a width of the slit-shaped vapor hole is in a range of 0.1 mm to 0.7 mm.
[7] Filling a molding space formed by the bead-method foamed synthetic resin molding die according to any one of [1] to [ 6 ] with a foamed thermoplastic resin bead and heating the foamed bead with steam Then, a method for producing a foamed synthetic resin molded product of a bead method, in which a molded product of a foamed synthetic resin having a required shape is produced by fusing, cooling and drying.

According to the bead method foam synthetic resin molding die and the method for producing the bead method synthetic resin molded product according to the present invention, the following significant effects are mainly obtained.
(1) Since the vapor holes of the mold are formed in a slit shape by cutting or the like, there is no need to drive the core vent into a large number of vent holes, so that the mold is deformed or damaged based on the driving work. In addition, the mold deformation and noise associated with the driving operation are eliminated.
(2) Since the vapor holes of the mold are formed in a slit shape by cutting or the like, the drilling operation for forming a large number of vent holes in the mold is not required, so that the strength is hardly lowered. Moreover, since the core vent driving operation and the polishing operation for smoothing the mold surface (molding surface) are not required, the manufacturing cost of the mold can be reduced.
(3) Since the vapor holes are slit-like, the traces of the vapor holes on the surface of the molded product are inconspicuous, so that a molded product with a beautiful surface property can be molded and the thickness of the mold can be reduced. Since the heat capacity is reduced, the heating and cooling time can be shortened and the weight of the mold can be reduced.
( 4 ) Since the steam hole is formed in a slit shape at a required portion of the mold by cutting or the like, even when the steam hole opening ratio needs to be increased so that a large amount of steam can be efficiently supplied into the molding space By changing at least one of the length and width of the slit-like steam holes and the interval between the adjacent steam holes, the steam hole opening ratio can be easily increased.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a bead-method foamed synthetic resin molding die according to an embodiment of the present invention, wherein (a) shows a core mold and (b) shows a cavity mold. It is a longitudinal cross-sectional view which shows the formation method of the slit-like vapor hole by the cutting process to the required location of the bead method synthetic resin molding metal mold, (a) is the state which is processing with a metal saw, (b) is processing A state in which the metal saw is later separated from the mold is shown. It is a principal part enlarged front view which shows the example of the slit-shaped vapor | steam hole formed in the metal mold | die for bead method foaming synthetic resin molding. It is a principal part enlarged front view which shows the example of the core vent drive | punched into the vent hole and vent hole formed in the conventional bead method foaming synthetic resin molding metal mold | die. It is a principal part enlarged front view which shows the example which shifted the position of the slit-shaped vapor hole in the opposing surface of a core type | mold and a cavity type | mold. The example which provided the slit-shaped vapor | steam hole in the attachment flange part of a metal mold | die is shown, (a) is a perspective view, (b) is a fragmentary sectional perspective view. It is an end view showing an example in which a slit-like steam hole is provided on a spherical surface which is a curved surface portion of a spherical mold. It is an end view showing an example in which a steam hole by a vent hole and a core vent is provided on a spherical surface which is a curved surface portion of a spherical mold. (A) is a perspective view which shows the example which provided the slit-shaped vapor hole along the surface shape change part (side edge part of a bottom face protruding item | line part) of a metal mold | die, (b) is a principal part expanded partial cross-section perspective view. . (A) is a perspective view which shows the example which provided the slit-shaped vapor hole along the surface shape change part (side edge part of a side surface protruding item | line part) of a metal mold | die, (b) is a principal part expanded partial cross-section perspective view. . (A) is a perspective view which shows the example which provided the slit-shaped steam hole along the surface shape change part (side edge part of a bottom face groove part) of a metal mold | die, (b) is a principal part expanded partial cross-section perspective view.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments shown in the accompanying drawings, and includes all the embodiments that satisfy the requirements described in the claims. It is a waste.

A beaded foam synthetic resin molding die 1 according to an embodiment of the present invention includes a core die (convex die) 2 shown in the perspective view of FIG. 1A and a cavity shown in the perspective view of FIG. It consists of a mold (concave mold) 3 and is used by being attached to a general molding apparatus (not shown).
In the bead method foaming synthetic resin molding, the molding space is formed by filling the molding space formed by the core mold 2 and the cavity mold 3 with the thermoplastic resin foam beads from the raw material filling port 5, and the foam beads are vaporized. The molded product of foamed synthetic resin having a required shape is obtained by inserting and extruding the release pin from the release pin opening 6 after being heated and fused with, cooled and dried.
Here, the expanded beads filled in the mold are a concept including pre-expanded beads obtained by pre-expanding expandable beads.

As the foamed synthetic resin used in the bead method foamed synthetic resin molding, for example, a foamed polyolefin resin or a foamed polystyrene resin is used.
When the foamed synthetic resin is a foamed polyolefin-based resin, it is possible to mold a molded article having excellent strength and heat resistance as well as oil resistance and chemical resistance using the beaded foam synthetic resin molding die 1. .
Further, when the foamed synthetic resin is a foamed polystyrene-based resin, it is possible to mold a molded product that is excellent in heat insulation and shock absorption and is lightweight and low-cost using the bead method foamed synthetic resin molding die 1.

A bead-method foamed synthetic resin molding die 1 (core die 2 and cavity die 3) shown in FIG. 1 is made of, for example, an aluminum alloy, and is formed into a three-dimensional shape by machining and / or casting.
In the present invention, for forming a three-dimensional mold, the cutting and / or casting is a single die for cutting, a die formed by assembling partial cut portions, a single casting die, It means a broad concept including a mold that assembles a partial cast part, a mold that assembles a cut part and a cast part, and the like.
In the example of FIG. 1, the cavity mold 3 of FIG. 1 (b) is a unit in which a side surface mold 3 </ b> A and a bottom surface mold 3 </ b> B formed as separate bodies are fastened and integrated with each other in order to obtain dimensional accuracy. The core mold 2 of 1 (a) is integrally formed from the beginning. Note that the side surface mold and the bottom surface mold formed separately from the core mold 2 may be assembled and integrated, or the cavity mold 3 may be formed as an integral part from the beginning.
In the core mold 2 and the cavity mold 3, steam holes 4, 4,.
The slit-shaped vapor holes 4, 4,... Are formed on the outer surface side and / or the inner surface side of required portions of the core mold 2 and the cavity mold 3.
Here, the slit-shaped vapor holes 4, 4,... Arranged on the side surfaces of the core mold 2 and the cavity mold 3 are provided along the opening / closing direction of the mold, so that the molded product is hardly caught and scratched.

Next, a method of forming slit-like vapor holes 4, 4,... In the bead-method foamed synthetic resin molding die 1 (core die 2 and cavity die 3) will be described with reference to the longitudinal sectional view of FIG. .
In addition, the slit-like steam hole said by this invention is directly formed in metal mold | die itself, and in the core vent etc. which are driven in the vent hole formed in the metal mold | die, the slit previously formed in the molding space side surface etc. Vapor-like vapor holes are not included.
With the metal saw 7 attached to the spindle of the horizontal machining center and the core mold 2 or cavity mold 3 fixed to the table, cutting is performed with the metal saw 7 as shown in FIG. 2 (a). As described above, by separating the metal saw 7 from the core mold 2 or the cavity mold 3 and repeating such operations, slit-like steam holes 4, 4,... Are formed at required locations of the core mold 2 or the cavity mold 3. .

In addition, since the vapor holes 4, 4,... Are slit-like, the corner R portion (corner R portion) which is a curved portion of the bead method foamed synthetic resin molding die 1 (core die 2 and cavity die 3) is formed. Even if the steam holes 4, 4,... Are formed, the corner R portion (corner R portion) is flush with the corner R portion (corner R portion) which is a curved surface portion C as shown in FIG. Steam holes 4, 4,... Can be formed.
In this way, the outer peripheral surface of the metal saw 7 is cut while the metal saw 7 attached to the horizontal main shaft is rotated with respect to the core mold 2 or the cavity mold 3 using a horizontal machining center suitable for processing a three-dimensional workpiece. The slit-shaped vapor holes 4, 4,... Can be efficiently processed by the blade.
The formation of such slit-like vapor holes 4, 4,... Is preferably performed by a machining center with a metal saw attached as a tool, particularly a horizontal machining center with a metal saw attached to a horizontal main shaft. It can also be carried out by removal using a machine or a wire electric discharge machine.

Here, the length of the slit-like steam hole 4 is determined by the outer diameter of the metal saw 7, and the width of the slit-like steam hole 4 is determined by the blade thickness of the metal saw 7. Since the minimum blade thickness of the metal saw 7 is about 0.02 mm, and the metal saw 7 having a thin blade thickness is selected, the width B (see FIG. 3) of the slit-like steam hole 4 becomes very small. Since the traces of the holes 4, 4,... Are almost inconspicuous, a molded product with a more beautiful surface property can be formed.
However, when the metal saw 7 with a thin blade thickness is selected, the beauty of the surface property of the molded product is improved, but it is necessary to form a large number of vapor holes 4, 4,. Decreases.
Therefore, the blade width of the metal saw 7 is preferably in the range of 0.1 mm to 0.7 mm, more preferably in the range of 0.3 mm to 0.5 mm.

Further, as shown in FIGS. 1 and 2, in the core mold 2 or the cavity mold 3 in which the slit-like vapor holes 4, 4,... Are formed, there is no depression around the slit-like vapor holes 4, 4,. Therefore, it is not a shape having many depressions on the surface opposite to the mold surface (molding surface) as in the conventional mold (for example, see Patent Documents 1 to 3), but formed by the core mold 2 and the cavity mold 3. There is no depression where the cooling water stays on the surface opposite to the molding space.
In addition, in the core mold 2 or the cavity mold 3 in which the slit-like steam holes 4, 4,... As shown in FIGS. Thus, at the slit-like vapor hole position, a structure can be formed in which there is no depression in which cooling water stays on the surface opposite to the molding space formed by the core mold 2 and the cavity mold 3.

Next, the steam hole opening ratio of the slit-shaped steam holes 4, 4,...
In the 100 mm square shown in FIG. 4, 25 vent holes 8, 8,... With a diameter of 10 mm are formed, and core vents 9, 9,... Are driven into these vent holes 8, 8,. Consider a case where the core mold 2 or the cavity mold 3 according to the present invention has a vapor hole opening ratio equivalent to 2 ′ or the cavity mold 3 ′.
As shown in FIG. 3, when 21 slit-like steam holes 4, 4,... Are formed, the length A of the steam hole 4 is 22 mm, the width B of the steam hole 4 is 0.3 mm, and the adjacent steam holes 4, When the interval D of 4 is set to 15 mm, the opening ratio of the steam holes by the core vents 9, 9,.
That is, since the steam hole opening ratio can be easily changed by changing at least one of the length A of the steam hole 4, the width B of the steam hole 4, and the distance D between the adjacent steam holes 4, 4, the molding space Even when it is necessary to increase the steam hole opening ratio so that a large amount of steam can be efficiently supplied to the inside, the steam hole opening ratio can be easily increased.

Here, the distance D between the vapor holes 4 and 4 is preferably in the range of 10 mm to 50 mm, and more preferably in the range of 15 mm to 30 mm. The intervals D between the steam holes 4 and 4 may be equal intervals or unequal intervals.
Moreover, as the examination of the blade width of the metal saw 7 takes into consideration the beauty and productivity of the surface property of the molded product, the range of the width B of the slit-like steam hole 4 is 0.1 mm to 0.7 mm. Preferably it is 0.3 mm-0.5 mm.
Furthermore, the length A of the slit-like vapor hole 4 is preferably in the range of 20 mm to 100 mm, and more preferably in the range of 30 mm to 70 mm.
By making the length A of the slit-shaped vapor hole 4 in the range of 20 mm to 100 mm, more preferably in the range of 30 mm to 70 mm, the slit-shaped vapor is suppressed while suppressing the strength reduction of the mold due to the length A being too long. It is possible to form a molded article having a beautiful surface property by making the holes 4, 4,... Less noticeable, and to reduce the number of slit-like vapor holes 4, 4,.
Therefore, since the processing time for forming the slit-like vapor holes 4, 4,... Can be shortened, the manufacturing cost of the mold can be reduced.
Here, the slit-like vapor holes 4, 4,... Are formed in an in-plane direction (width D in FIG. 3) perpendicular to the longitudinal direction of the vapor holes 4 when a large number of vapor holes 4, 4,. 3) may be arranged in parallel so that the end portions of the steam holes 4, 4,... Are aligned as shown in FIG. You may stagger and arrange | position. In order to increase the strength of the mold with the same vapor hole opening ratio, it is preferable to arrange the slit-shaped vapor holes 4, 4,.

As described above, the smaller the width B of the slit-like vapor hole 4 is, the more difficult it is to make the slit-like vapor hole noticeable, and it is possible to form a molded product with a beautiful surface property. If it is small, it is necessary to increase the length A of the steam holes 4 or increase the number of the steam holes 4 by narrowing the interval D in order to obtain the required steam hole opening ratio. The width B of the steam holes 4 and the interval D between the adjacent steam holes 4, 4 are determined in consideration of the processing time for forming the steam holes 4, 4,.
What is important about the slit-like vapor hole of the present invention is that the degree of freedom in design is high, so that it can be appropriately designed so as to obtain good heating and fusion according to the shape of the molded product and the shape of the mold. .

As shown in FIG. 4, in the core mold 2 'and the cavity mold 3' in which the core vents 9, 9, ... are driven into the vent holes 8, 8, ..., the height of the core vent 9 is usually 6 mm or more, which is higher than this. Low core vents are custom made and expensive. Therefore, the use of such a custom-made core vent with a low height is extremely disadvantageous for the production of a mold in which cost is important.
Therefore, the thickness of a normal mold is 9 mm to 13 mm so as to withstand a load when a core vent having a height of 6 mm or more is driven and to prevent an irregular bending deformation or the like in the mold.
On the other hand, if the slit-shaped vapor holes 4, 4,... Of the present invention are employed, the thickness restriction like a mold having a structure in which the core vents 9, 9,. Therefore, the thickness of the core mold 2 and the cavity mold 3 can be set to about 3 mm to 8 mm, more preferably about 5 mm to 7 mm in the case of a polystyrene foam resin.
Therefore, it is possible to significantly reduce the weight by reducing the thickness and reduce the amount of steam that is excessively consumed by heating and cooling the mold during molding. Significant reduction is possible. Moreover, since the molding pressure in the case of the foamed polyolefin resin is high, it is preferable to increase the thickness to about 1.2 to 1.3 times that in the case of the foamed polystyrene resin.

Further, as shown in the enlarged front view of the main part of FIG. 5, the slit-like steam holes 4, 4,... Forming 4,... Is a more preferred embodiment.
In this way, by forming the slit-shaped vapor holes 4, 4,... Of the core mold 2 and the cavity mold 3 in a shifted manner, the passage distance when the vapor passes through the molding space becomes long, so the foam beads in the molding space. Since it becomes easy to heat and melt, a high-quality molded product can be obtained.
When the slit-shaped vapor holes 4, 4,... Of both the core mold 2 and the cavity mold 3 have the same pitch as shown in FIG. 5, for example, the slit-shaped vapor holes 4, 4,. What is necessary is just to form.

The interval between the slit-like vapor holes 4, 4,... Is denser as the distance from the raw material filling port (see, for example, reference numeral 5 in FIG. 1B) is larger (the vapor hole opening ratio is larger), and the closer to the raw material filling port, the smaller By making the vapor hole opening ratio small, it is preferable because the filling of the raw material becomes good. That is, with respect to the vapor hole opening ratio of the beaded foam synthetic resin molding die, the part that forms the tip of the foamed synthetic resin molded product that is far from the raw material filling port of the mold, particularly the part that forms the thin tip It is preferable that the vapor hole opening ratio is increased and the vapor hole opening ratio other than the portion forming the tip of the molded product is decreased.
Here, the ratio of the vapor hole opening ratio of the part forming the tip of the molded product to the vapor hole opening ratio of the part forming other than the tip is 3: 1 to 10: 1, preferably 5: 1. It should be in the range of ˜7: 1.
By doing in this way, in the foamed synthetic resin molded article, far from the raw material filling port of the bead method foamed synthetic resin molding die, even the tip of the foamed synthetic resin molded article, particularly the thin-walled tip, The foamed beads can be uniformly filled, and a molded product of good quality can be obtained in a short molding cycle.

Unlike the conventional core vent, the slit-shaped vapor hole of the present invention can be easily formed not only on the flat surface portion of the mold but also on the curved surface portion (for example, the corner R portion or the corner R portion). Therefore, in order to make the surface state of the molded product more beautiful, it is preferable to concentrate the slit-shaped vapor holes densely on the curved surface portion of the molded product. As a result, the slit-shaped vapor hole traces in the flat part are inconspicuous, and the slit-shaped vapor hole traces are arranged on the curved surface part that is not easily noticeable to the human eye while ensuring the supply of heated steam at the time of molding. Good product aesthetics are achieved. In particular, it is most preferable to arrange a slit-like vapor hole trace at the corner R portion of the cavity mold.
Moreover, the slit-shaped vapor hole of this invention can be provided in various shape parts, such as front-end | tips, such as uneven | corrugated | grooved parts other than R part, or a rib part, and / or a root.

Next, a modified example of the place where the slit-like vapor holes 4, 4,... Are formed will be described.
In the perspective view of FIG. 6 (a) and the partial cross-sectional perspective view of FIG. 6 (b), slit-like steam holes 4, 4,... Formed in the flange portion F of the mold are open to the outside. An example is shown.
Here, in the core mold 2 ′ and the cavity mold 3 ′ in which the core vents 9, 9,... Are driven into the vent holes 8, 8,. Since both ends of the vapor hole are surrounded by the wall surface of the core vent 9 or the wall surface of the mold in which the vent hole 8 is formed, it always has a closed shape.
On the other hand, the slit-like steam holes 4, 4,... Formed in the flange portion F of the mold as shown in FIG. 6 are not closed, but are open to the outside (shapes with slits to the outer periphery). Therefore, the degree of freedom in the design of the steam holes is increased and the opening ratio of the steam holes can be increased.

The end view of FIG. 7 shows an example in which slit-like vapor holes 4, 4,... Are provided on the spherical surface which is the curved surface portion C of the spherical mold.
Here, in the spherical mold having a structure in which the core vents 9, 9,... Are driven into the vent holes 8, 8,... As shown in the end view of FIG. It is difficult to drive properly. In addition, since the end surfaces of the core vents 9, 9,... Are flat, a circular flat portion is formed at the location of the core vents 9, 9,. A spherical surface is not formed.
On the other hand, the formation of the slit-shaped vapor holes 4, 4,... In the spherical surface, which is the curved surface portion C shown in FIG. 7, can be performed relatively easily by cutting with a machining center to which a metal saw is attached as a tool. .
Further, since the slit-like vapor holes 4, 4,... Formed in the spherical surface as shown in FIG. 7 have a narrow width (for example, 0.1 mm to 0.7 mm), a relatively smooth spherical surface is formed in the molded product. At the same time, the traces of the vapor holes 4, 4,.

FIG. 9A is a perspective view, FIG. 9B is an enlarged partial cross-sectional perspective view of the main part, FIG. 10A is a perspective view, and FIG. 10B is an enlarged partial cross-sectional perspective view of the main part. 11 (a) and an enlarged partial sectional perspective view of the main part of FIG. 11 (b) show an example in which slit-like steam holes 4, 4,... Are provided along the surface shape changing portion E of the mold. ing.
Here, the example of FIG. 9 is along the side edge portion of the bottom surface protruding portion G that is the surface shape changing portion E of the core mold 2, and the example of FIG. 10 is the surface shape changing portion E of the core die 2. Along the side edge of the side ridge H, the example of FIG. 11 forms slit-like vapor holes 4, 4,... Along the side edge of the bottom groove I which is the surface shape changing portion E of the core mold 2. doing.
By forming slit-like vapor holes 4, 4,... In the mold surface shape changing portions such as the uneven portions and the side edges of the rib portions as exemplified in these, the slit-like vapor holes 4 of the molded product are formed. , 4... Are not conspicuous, so that the designability by the pattern attached to the molded product formed by the concavo-convex part and the rib part is not impaired.

  As described above, in the bead-method foamed synthetic resin molding die 1 of the present invention, slit-like vapor holes can be formed at locations that could not be formed by a die having a structure in which a core vent is driven into a vent hole.

Further, according to the configuration of the mold 1 for molding foamed synthetic resin (core mold 2 and cavity mold 3) of the present invention, the vapor holes 4, 4,... Of the mold 1 are formed in a slit shape by cutting or the like. This eliminates the need to drive core vents into a large number of vent holes, as is the case with conventional beaded foam synthetic resin molding molds formed by driving core vents into the mold vent holes. Therefore, there is no deformation or damage of the mold based on the driving operation, and noise associated with the driving operation is eliminated.
In addition, drilling work for forming a large number of vent holes in the mold, the driving work, and polishing work for smoothing the mold surface (molding surface) are not required, thus reducing the manufacturing cost of the mold. it can.

Further, as in Patent Document 1, the inner diameter of the vent hole is made slightly larger than the outer diameter of the vent fitting, and a circumferential groove for accommodating an adhesive is formed in the vent fitting, and the vent fitting is manually attached to the vent hole. Because the vapor holes 4, 4,... Of the mold 1 are formed in a slit shape by cutting or the like for what is inserted and bonded, it is not necessary to use a specially shaped vent fitting with a circumferential groove. The drilling process for forming the vent hole so that the clearance with the vent metal fitting is in the range of 0.05 mm to 0.1 mm is not necessary, and the adhesive is applied to the peripheral groove of the vent metal fitting. Therefore, the manufacturing cost of the mold can be reduced.
Furthermore, as in Patent Document 2, a metal plate is joined to the cavity-side surfaces of a pair of molds in which steam holes are drilled by a normal punching process, and a narrow groove-like shape communicating with the steam holes is connected to the metal plate. Since the steam holes 4, 4,... Of the mold 1 are formed in a slit shape by cutting or the like, the metal plate is attached to the mold having a large number of circular steam holes. Since it is not necessary to form a steam slit in the metal plate after joining the metal plate to the mold, it is possible to drill circular steam holes in the die, Since it is not necessary to perform joining and processing of the steam slit to the metal plate joined to the mold, the manufacturing cost of the mold can be reduced.

Further, since the steam holes are slit-like to the conventional general bead method foam synthetic resin molding die and the bead method foam synthetic resin molding die of Patent Document 1, the surface of the molded product is Since the traces of the formed vapor holes are not conspicuous, the surface property of the molded product can be made beautiful.
Furthermore, since the core vent is not required by making the steam hole into a slit shape, there is no need for drilling the vent hole into the mold, and there is no need to hit the mold for driving the core vent. Since no load is applied to deform the mold, the thickness of the mold can be made very thin. Therefore, since the heat capacity of the mold is reduced, the heating / cooling time can be shortened and the weight of the mold can be reduced.
Furthermore, since the vapor holes 4, 4,... Are slit-shaped, even if the vapor holes are formed in the curved surface portion of the mold, the curved surface portion of the mold is flush with the curved surface portion of the mold. Vapor holes can also be formed.

Further, with respect to the conventional general bead method foam synthetic resin molding die and the bead method foam synthetic resin molding die of Patent Documents 1 and 2, cooling is performed on the surface opposite to the molding space of the die. Except for the depression where the cooling water sprinkled in the process stays, or on the surface on the opposite side of the molding space of the mold, except for the mounting flange part of the mold and / or the part where water can be removed naturally. Since there is no recess in which the cooling water sprayed in the cooling process stays, the time required for the drying process can be shortened.
Furthermore, in contrast to the conventional general bead-method foamed synthetic resin molding die and the bead-method foamed synthetic resin molding die of Patent Documents 1 and 2, steam holes are formed by cutting or the like at the required locations of the die. Since it is formed in a slit shape, the length and width of the slit-shaped steam holes and the adjacent steam holes are required even when the steam hole opening ratio needs to be increased so that a large amount of steam can be efficiently supplied into the molding space. By changing at least one of the intervals, the vapor hole opening ratio can be easily increased.

1 Bead Mold Foam Synthetic Mold 2, Core 3, 3 ′ Cavity 3 A Side 3 B Bottom 4 Slit Vapor Hole 5 Material Filling Port 6 Release Pin Opening 7 Metal Saw 8 Vent Hole 9 Core vent A Length of slit-like steam hole B Width of slit-like steam hole C Curved portion D Spacing between adjacent steam holes E Surface shape change portion F Mold mounting flange G Bottom ridge H Side ridge I Bottom groove

Claims (7)

A molding space formed by a pair of molds consisting of a core mold and a cavity mold is filled with foamed beads of thermoplastic resin, the foamed beads are heated and fused with steam, cooled and dried, and foamed in a desired shape. The mold used for molding the synthetic resin by a bead method to obtain a synthetic resin molded article,
A slit-like steam hole directly formed in the mold itself for allowing the steam to communicate with the inside and outside of the mold through a required portion of the three-dimensional mold formed by cutting and / or casting. I have a,
A beaded foam synthetic resin molding die, wherein the slit-shaped vapor hole is formed from a metal saw attached to a main shaft of a horizontal machining center . Among the slit-shaped steam holes, one provided in the mounting flange portion of the mold, beads method foamed synthetic resin molding mold according to claim 1 which is open to the outside. 3. The beaded synthetic resin molding die according to claim 1, wherein the slit-shaped vapor hole is provided at least in a curved portion of the die. The bead-method foamed synthetic resin molding die according to claim 1 or 2 , wherein the slit-shaped vapor hole is provided along a surface shape changing portion of the die.   2. The beaded foam synthetic resin molding die according to claim 1, wherein the slit-like vapor holes arranged on a side surface of the die are provided along an opening / closing direction of the die. The bead-method foamed synthetic resin molding die according to any one of claims 1 to 5 , wherein a width of the slit-shaped vapor hole is in a range of 0.1 mm to 0.7 mm. A thermoplastic resin foamed bead is filled in a molding space formed by the bead-method foamed synthetic resin molding die according to any one of claims 1 to 6 , and the foamed bead is heated and fused with steam. The method for producing a foam synthetic resin molded product of a bead method, in which a molded product of a foam synthetic resin having a required shape is produced by cooling and drying.

Images