JPS61188131A - Foam molding - Google Patents

Abstract

PURPOSE:To enable to extremely easily and efficiently manufacture a large molded part by a method wherein a molding tool, which is formed of a FRP resin skin member whose back is reinforced, is used instead of conventional molds. CONSTITUTION:Green FRP resin is put along the outer surface of the master model 1 so as to laminate up to a certain thickness in order to form skin members 2 by hardening. Horizontally extended flanges 20 are made on the outer peripheries of the skin members, the upper and the lower ones of which oppositely but against each other through the flanges 20. The skin members 2 are removed from the master model 1 in order to manufacture molding tools M by reinforcing its back. In addition, cooling piping 5 is imbedded in each molding tool M at the position at a small distance apart from the back of the skin member 2. By closing a vertical pair of the molding tools M by mating the flanges 20 of the skin members 2, which from the inner surface sides of the molding tool M, with each other, a cavity corresponding to the outer shape of the master model 1 is formed in the interior of the skin members 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a foam molding method, and more particularly, to a method for producing a molded article by heat-sealing expandable thermoplastic resin particles within a mold cavity of a mold.

<Prior Art> In the above foam molding method, the mold is very important in order to obtain a foam molded product with a desired shape.

Conventionally, a mold made of gold R/R& has been used as a mold, which has good mold precision and excellent durability.

However, the above-mentioned molds have the disadvantage that they require technology to manufacture and are very costly. In addition, in the case of molds, there is a limit to the manufacturing dimensions, making it difficult to manufacture very large molded products, and there is also a limit to the capacity of the molding machine that carries out molding with the mold installed. It was impossible to produce molded articles. Furthermore, when manufacturing a mold, it is necessary to manufacture a wooden model in advance and then manufacture the mold by means such as casting or cutting according to the shape of the wooden model. It took a lot of effort and time.

Therefore, in the case of molds, the method is not cost-effective unless the amount of molded products produced is quite large, and is not suitable for small-volume production of molded products with a small number of products.

It has also been proposed to use a mold made of gypsum or the like for vacuum forming foam sheets instead of the above mold, but gypsum has poor strength and is not suitable for bead molding where strong foaming pressure is applied. Although it was suitable, the mold accuracy was also poor, and it was not practical because it was impossible to manufacture large molds.

Therefore, as an object of the present invention, it is possible to solve the problems of the above-mentioned prior art, easily manufacture large molded products, and
We are trying to develop a foam molding method that can be used to manufacture molded products in small quantities at low cost.

A method for achieving the above purpose includes a step of laminating FRP resin along the outer surface of the prototype model to form a skin material for the mold, and reinforcing the back surface of the skin material. In the step of forming a mold, after filling the mold cavity of the mold with expandable thermoplastic resin particles, a heating probe is inserted into the mold cavity, and the resin particles are heated by the heating medium ejected from the heating probe. It is characterized by the process of manufacturing molded products by heating and fusing the materials.

<Example> Next, an example of the present invention will be described below with reference to the drawings.

1 to 5 show the manufacturing process of a surfboard core material as a molded product in the order of steps.

In Figure 1, (1) is the prototype model, in which, in addition to the conventional wooden mold, the actual foam molded product manufactured in the past can be used as is, or the block-shaped foam can be cut into the desired shape. It can also be molded, and does not require the precision and strength of wooden molds for traditional mold making.
' Then, as shown in FIG. 2, uncured FRP resin is pasted along the outer surface of the prototype model (1), laminated to a certain thickness, and hardened and molded to form a skin material (a).

In addition, in the figure, the original model (1) is divided into two parts, upper and lower, and FRP resin is laminated separately on the upper and lower parts.
A pair of skin materials (2) are formed which are divided into two parts, upper and lower. Further, a flange (20) extending in the horizontal direction is formed on the outer periphery of the skin material (2), and the upper and lower skin materials (a) are in contact with each other and face each other.

After the skin material S2) is hardened and formed, the skin material (2) is peeled off from the original model (1). In addition, the prototype model (1
) When laminating FRP resin on the original model (1)
It is preferable to apply a mold release agent to the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface material (2) to facilitate the work of peeling off the surface material (2).

Next, as shown in FIG. 3, the back side of the skin material (2) is reinforced to produce a mold (M). That is, as shown in detail in Fig. 6, first, a cross-shaped rigid frame (3) made by combining rigid materials such as steel vertically and horizontally is joined to the back of the skin material (2), and then the skin material (2) is attached. This prevents the deformation of the material (2) and improves its rigidity.In addition, a filler material (4) such as gypsum is used in the space created between the crosspiece-shaped rigid frames (3).
) is filled and hardened to embed the entire rigid frame (3), and this filler (4) also reinforces the back surface of the skin material (2).

□Furthermore, a cooling arrangement pipe (5) is buried at a small distance between it and the back surface of the skin material (a).In other words, the cooling pipe (5) is installed at appropriate locations on the entire surface of the mold (H). S penetrates a part of the rigid frame (3) and is embedded inside the filler (4), and is formed so that cooling water and cooling air can be introduced into the cooling pipe (5). This serves to accelerate the cooling of molded products.

A pair of upper and lower molds (H) configured as above,
As shown in Figure 4, by aligning the flanges (20) of the skin material (2) on the inner side and closing the mold, the skin material (2)
There is a mold cavity (C) corresponding to the external shape of the original model (1) inside.
is formed. In addition, in order to reliably fix the mold closed state, the molds (H) may be fixed to each other by a fastening mechanism such as a bolt.

In this state, a filling nozzle is inserted into the mold cavity (C) to fill the mold cavity (C) with expandable thermoplastic resin particles.

Therefore, in part of the mold (H) and the skin material (2),
An insertion hole for the filling nozzle is formed in advance.

Next, a heating probe (6) is inserted into the mold cavity (C) instead of the filling nozzle. Then, a heating medium such as heated steam is ejected from the tip of the heating probe (6), and the resin particles in the mold cavity (C) are heated and R-foamed to fuse and integrate them, which is called probe molding. That is, as shown in FIG.
First, the heating probe (6) is inserted deep into the mold cavity (C), and the heating medium is ejected from the heating probe (6) to heat and fuse the resin particles at that location, causing the resin particles to fuse and harden. At the same time, gradually pull out the heating probe (6),
As the heating probe (6) is extracted and moved, the mold cavity (C
) The entire resin particles are heated and fused to produce a molded product (P).

Note that the probe molding itself is performed using a conventionally known method and W4.
It can be carried out by various methods, and as a precedent example of Plow 7 molding,
For example, Japanese Patent Publication No. 52-32781 or Jikko No. 3
It is disclosed in Japanese Patent No. 4-4689 and the like.

After heating and fusing the resin particles in the entire mold cavity (C) as described above, the entire mold (H) is cooled and the molded product (P
) is cooled and hardened, and then the mold (H) is opened and the molded product (P) is taken out, completing the foam molding.

As shown in FIG. 5, the manufactured molded product (P) has the same external shape as the original model (1), and a heating probe (6) is inserted into the molded product (P). A small hole (h) remains where it had been.

In addition, by closing the mold (H) and repeating each process sequentially starting from the step of filling the expandable thermoplastic resin particles, the molded product (P) can be manufactured repeatedly. Although it does not have any durability, if the number of pieces is relatively small, molded products (
It is quite possible to repeatedly produce P).

Among the foam molding methods explained above, the original model (1)
As a skin material made of FRPil [1f] (it only needs to be strong enough not to deform or collapse when forming the glue, a precise wooden mold like the conventional one is not required, and a model made of foam or plaster is sufficient) In particular, if the actual molded product (P) manufactured in the past is used as the prototype model (1), the manufacturing cost will be lower, the external shape will be more accurate, and it will be practical and suitable. It will be implemented.

Next, as the formation process of the skin material (2), the original model (
1) is divided into appropriate parts and a separate skin material ('2
J may be manufactured, and the number and division positions of the skin material (2) can be changed as appropriate depending on the shape of the prototype model (1). In addition, by forming a flat flange (2G) as shown in the figure at the seam between the plurality of skin materials (2), it is possible to easily form the mold (H), and also to facilitate the molding process. Accurate mold matching is possible. Note that the thickness of the FRP resin laminated as the skin material (2) may be relatively thin, and even for a large molded product (P), a thickness of approximately 10 mm is usually sufficient.

In the manufacturing process of the mold (H), structural materials with excellent rigidity and strength such as steel, various metal materials, and wood can be freely used for the rigid frame (2). All that is required is to combine the rigid frame (2) vertically and horizontally in the shape of a frame and reinforce the skin material (2), and the combination pattern of steel materials, the number of pieces used, etc. can be changed as appropriate other than those shown in the drawings. ] to the skin material (a).In addition to using adhesive, the rigid frame (3) is brought into contact with the back surface of the skin material (a) before the FRP resin that becomes the skin material (2) hardens. If this is done, the rigid frame (3) can be joined at the same time as the skin material (2) is cured.

The filling material (4) that fills the space of the rigid frame (3) can be easily filled and hardened, such as plaster or plaster, and has a certain degree of rigidity. In collaboration with
It is preferable to use a material that can prevent deformation of the skin material (2). In addition, especially inside the filler (4), there is a cooling pipe C5.
When buried, it is desirable to use a material that has good heat conductivity during cooling.

Note that the cooling pipe (5) is effective for promoting cooling of the molded product (P) and the mold (H) after molding, but it is also possible to cool the molded product (P) and mold (H) by cooling only without using the cooling pipe (51). This is possible.Furthermore, the mold (H) may be provided with cooling fins.

Next, in the molding process, the expandable thermoplastic resin particles to be filled into the mold cavity (C) may be expandable particles made of polystyrene, polyethylene, polypropylene, styrene-ethylene copolymer, or other various thermoplastic resins. It can be used to suitably select and use depending on the purpose of the molded product (P).

Depending on the shape and size of the mold cavity (C), multiple heating probes (6) can be inserted at the same time to quickly heat the resin particles and improve the efficiency of the molding process. can be improved. In particular, as shown in Figure 7, the mold cavity (
Insert the heating probe (6) from both ends of the mold cavity (C).
By heating simultaneously from the center to both ends of the heating probe (C), the insertion length of the heating probe (0) can be shortened, and the heating efficiency is also good and suitable. The thermal fusion of resin particles is controlled by adjusting the temperature, injection amount, etc.

<Effects> According to the method of the present invention configured as described above, a mold formed by reinforcing the back surface of the skin material (2) made of FRP resin, without using a conventional mold as a mold. Type (
H) is used. The method for forming the skin material C2) is to directly apply FRP to the outer surface of the original model (1).
Since it is formed by laminating and curing resin, it can be formed very easily and efficiently. In addition, there is no need to create a wooden mold, and it becomes possible to form the skin material ('2J) directly from the actual model, making the manufacturing cost of the entire mold (H) much cheaper than that of a metal mold. Moreover, since the mold is taken directly from the original model (1), it is possible to manufacture the skin material (a, that is, the mold (H)) with an accurate shape corresponding to the external shape of the original model (1). However, the skin material of this invention (2) does not have the above limitations at all, although it is technically very difficult and costly to manufacture a product with a very large shape. , even quite large ones, can be manufactured without any problems and at a relatively low cost.

If only the thin skin material (2) is used, the rigidity and strength will be poor,
There is a risk of deformation due to the foaming pressure etc. in the foam molding process, but in this invention, the back surface of the skin material (a) is reinforced with a rigid frame (3) and filler (4), so the above deformation is guaranteed. The finishing accuracy of the molded product (P) is as accurate as that of conventional molds.The durability of the mold ('H) is also as high as that of the molded product (P).
Even if the mold (H) using the skin material (2) of the present invention is produced in a relatively small number, it can be used practically without any problems.

Next, the mold (Q) formed as described above is filled with raw resin particles by inserting a filling nozzle directly into the mold cavity (C) from the outside of the mold LH), and then heated with a heating probe. (6) is inserted into the mold cavity (C) and the resin particles are heated and fused by blowing out a heating medium such as steam,
By performing so-called probe molding to produce the molded product (P), there is no need to attach an attachment mechanism to a molding machine, a raw material filler, etc., as with conventional molds. Therefore, even with the mold (H) of this invention, which is somewhat inferior in strength and precision in external shape and difficult to form a WIM attachment mechanism, etc. compared to a mold, it is possible to perform foam molding satisfactorily. It is what it is.

In addition, since complicated equipment such as a molding machine is not required at all, and the molding work is easy, there are no restrictions on the size of molded products (P) due to the capacity of the molding machine, and large molded products (P) can be produced.
can also be formed freely.

For example, a surfboard core material having a length of 4000 m, a width of 600 m5, and a thickness of 160 cm was produced using the method of the present invention (P).

As described above, according to the method of this invention, large molded products (P), which have been difficult to produce in the past, can be produced extremely easily and efficiently, and especially molded products (P), which are produced in relatively small quantities, can be manufactured very easily and efficiently.
), it is very effective for foam molding applications or l! It can also greatly contribute to the expansion of

[Brief explanation of drawings]

The figures show embodiments of this invention, and are shown in Figures 1 to 5.
The figures are sectional views showing the sequential molding process, FIG. 6 is a perspective view of the main part at the stage of FIG. 4, and FIG. 7 is a schematic plan view. (1)...Prototype model, (a...Skin material, (3)...Rigid frame, (4)...
...Filling material, (5)...Cooling piping, β)...
... Heating probe, (H) ... Molding mold, (P
)······Molding. Figure 3 Figure 7

Claims (1)

[Claims] 1. FRP tree along the outer surface of the prototype model Form a layer of fat to create a skin material for molds. In the forming process, the back of the skin material is reinforced, The process of forming a mold, the mold of the above mold The cavity is filled with foamable thermoplastic resin particles. After that, insert the heating probe into the mold cavity, The heating medium ejected from the heating probe Therefore, by heating and fusing the resin particles, the The process of manufacturing shaped products. Characteristic foam molding method. 2. In the process of forming the skin material and mold First, divide the outer surface of the prototype model into two, Forms a pair of skin materials and corresponds to each skin material The above patent claimant forms a pair of molds that The foam molding method according to item 1. 3. In the mold forming process, the skin material A cross-shaped rigid frame is connected to the back, making it rigid. Filling the space between the frames with plaster, etc. Claim 1 above, which is filled with material. Foam molding method described. 4. In the mold forming process, the skin material Bury cooling piping near the back. Foamed foam according to claim 3 above shape method. 5. In the manufacturing process of molded products, the mold Insert the filling nozzle into the mold cavity to fill the resin particles. Claim 1 of the above claims Foam molding method described.