JPH0428741Y2 - - Google Patents

Description

[Detailed description of the invention] <Technical field> This invention relates to a mold for foam molding, and is used to manufacture molded products by heating and fusing expandable thermoplastic resin particles within the cavity of the mold. It is related to the mold to be used.

<Prior Art> Conventionally, metal molds are usually used as the molds for the above-mentioned foam molding, and the molds have good 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 time and effort to manufacture the mold.

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

In addition, it has been proposed to use a mold made of gypsum or the like for vacuum forming of foam sheets instead of the above mold, but gypsum is inferior in strength and is not suitable for bead molding where strong foaming pressure is applied. Although suitable, the mold precision was poor and it was not possible to manufacture large molds, making it impractical.

<Purpose> Therefore, the purpose of this invention is to solve the problems of the above-mentioned conventional technology, and to create a molding for foam molding that can easily produce large molded products and can also produce molded products in small quantities at low cost. I'm trying to provide a type.

<Structure> The structure for achieving the above object includes a mold that is filled with raw material particles made of a foamable thermoplastic resin, and that heat-fuses the filled raw material particles and molds them into a predetermined shape. Each mold cavity is separated by a pair of FRP resin skin materials that are laminated along the outer surface of the original model and divided into two parts. It is characterized by integrally forming a reinforcing material consisting of a rigid frame and a filler filled between the rigid frames.

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

Figures 1 to 4 show a mold M for producing core materials for surfboards as foam molded products, of which Figure 1 shows the mold in an open state, and Figures 2 to 4 show it Indicates the molding state.

Reference numeral 2 denotes a skin material, which is made by laminating FRP resin to a certain thickness, and is formed on the inner surface side constituting the mold cavity of the upper and lower mold M.

The manufacture of this skin material 2 will be explained in detail with reference to FIG. 4. First, 1 is a prototype model, and in addition to the conventional wooden mold, it can also be formed by using the actual foam molded product manufactured in the past, or by cutting a block-shaped foam into the desired shape. , it does not require the precision and strength of a wooden mold for traditional mold manufacturing.

Then, an 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 the skin material 2. 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 horizontally is formed on the outer periphery of the skin material 2, and the upper and lower skin materials 2
The flange portions 20 abut against each other and face each other.

After the skin material 2 is hardened and formed, the skin material 2 is peeled off from the original model 1. In addition, the original model 1
When laminating the FRP resin, it is preferable to apply a mold release agent to the surface of the prototype model 1 in advance, as this makes it easier to perform the work of peeling off the skin material 2.

A mold M is formed by reinforcing the back side of the skin material 2 as described above. That is, as shown in detail in FIG. 2, first, a cross-shaped rigid frame 3, which is made by combining rigid materials such as steel vertically and horizontally, is joined to the back surface of the skin material 2 to prevent the skin material 2 from deforming. Improves rigidity and strength. In addition, in the space created between the frame-shaped rigid frames 3, a filler 4 such as plaster is filled and hardened to embed the entire rigid frame 3, and this filler 4 also covers the back surface of the skin material 2. It is reinforcing.

Furthermore, a cooling pipe 5 is buried between the back surface of the skin material 2 and a slight space therebetween. That is, at appropriate locations on the entire surface of the mold M, cooling pipes 5 are embedded inside the filler 4 by penetrating a part of the rigid frame 3, and cooling water or cooling air can be introduced into the cooling pipes 5. The cooling of the molded product, which will be described later, is accelerated.

Next, a foam molding method using a pair of upper and lower molds M configured as described above will be described.

That is, by closing the upper and lower molds M by aligning the flanges 20 of the skin material 2 on the inner side, a mold cavity C corresponding to the outer shape of the original model 1 is formed inside the skin material 2. . In addition, in order to reliably fix the mold closed state, the molds M 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, an insertion hole for a filling nozzle is formed in advance in a part of the mold M and the skin material 2.

Next, the 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 to heat and foam the resin particles in the mold cavity C to fuse and integrate them, so-called probe molding. That is, as shown in FIG. 3, the heating probe 6 is first 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. The heating probe 6 is gradually pulled out as the particles are fused and hardened, and as the heating probe 6 is pulled out and moved, the resin particles in the entire mold cavity C are heated and fused, thereby manufacturing the molded product P.

The above-mentioned probe molding itself can be performed by a method similar to a conventionally known method, and prior examples of probe molding are disclosed in, for example, Japanese Patent Publication No. 52-32781 or Japanese Utility Model Publication No. 34-4689. .

After heating and fusing the resin particles in the entire mold cavity C as described above, the entire mold M is cooled to cool and harden the molded product P. After that, the mold M is opened, and the molded product P Once removed, the foam molding is complete.

The manufactured molded product P has the same external shape as the original model 1, as shown in FIG. h remains.

In addition, if the above-mentioned mold M is closed and each process is performed sequentially from the step of filling the expandable thermoplastic resin particles again, the molded product P can be manufactured repeatedly, and it is not as durable as conventional molds. However, if the number is relatively small, it is fully possible to repeatedly manufacture the molded product P.

Among the mold M and the foam molding method described above, the original model 1 only needs to have enough strength to not be deformed or crushed when forming the skin material 2 using FRP resin, and it is not necessary to use precision wood as in the conventional method. No mold is required; models made of foam, plaster, etc. are sufficient. Especially, as the prototype model 1,
If you use the actual molded product P manufactured in the past,
The manufacturing cost is low, the precision of the external shape is high, and the implementation is practical and suitable.

Next, for the skin material 2, it is sufficient to divide the prototype model 1 appropriately and manufacture separate skin materials 2 for each part, and the number of divisions of the skin material 2 is determined according to the shape of the prototype model 1. and the division positions can be changed as appropriate. In addition, by forming a flat flange 20 as shown in the figure at the joint between the plurality of skin materials 2, it is possible to easily form the mold M, and also to facilitate mold matching in the molding process. I can do it accurately. 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.

The rigid frame 3 that serves as a reinforcing material for the mold M may be made of steel, various metal materials, wood, etc.
Structural materials with excellent rigidity and strength can be used freely, and it is sufficient to combine the above materials in the form of crosspieces on the entire back surface of the skin material 2 to reinforce the skin material 2, and the combination pattern of steel materials etc. and the number of materials used can be changed. etc. may be modified as appropriate in addition to those shown in the drawings. In addition, as a means of joining the rigid frame 3 to the skin material 2, in addition to using an adhesive, the rigid frame 3 may be brought into contact with the back surface of the skin material 2 before the FRP resin that will become the skin material 2 hardens. For example, the rigid frame 3 can be joined simultaneously with the hardening of the skin material 2.

The filler 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, so that it can be molded together with the rigid frame 3. It is preferable to use a material that can improve the strength of the entire M and prevent deformation of the skin material 2. Moreover, especially when embedding the cooling pipe 5 inside the filler 4, a material with good heat conductivity during cooling is desirable.

Note that the cooling pipe 5 is effective for promoting cooling of the molded product P and the mold M after molding, but
It is also possible to perform cooling only by cooling without using the cooling pipe 5. Further, the mold M may be provided with cooling fins.

Next, in the molding process, the expandable thermoplastic resin particles to be filled into the mold cavity C are polystyrene,
Expandable particles made of polyethylene, polypropylene, styrene-ethylene copolymer, and various other thermoplastic resins can be freely used, and are appropriately selected and used depending on the purpose of the molded product P.

By inserting a plurality of heating probes 6 at the same time as appropriate depending on the shape and size of the mold cavity C, the resin particles can be heated quickly and the efficiency of the molding process can be improved. In particular, as shown in FIG. 3, by inserting the heating probe 6 from both ends of the mold cavity C and heating from the center to both ends of the mold cavity C at the same time, the insertion length of the heating probe 6 can be shortened. , heating efficiency is also good and suitable. Furthermore, the heat fusion of the resin particles is controlled by adjusting the extraction speed of the heating probe 6, the temperature of the heating medium, the injection amount, etc.

<Effects> According to the mold M for foam molding of this invention configured as described above, the mold is formed by reinforcing the back surface of the skin material 2 made of FRP resin without using a conventional mold. A mold M is used.
The skin material 2 is formed by laminating and curing FRP resin directly on the outer surface of the original model 1.
It can be formed very easily and efficiently. Furthermore, it is not necessary to produce a wooden mold, and it becomes possible to form the skin material 2 directly from the actual model, and the manufacturing cost of the entire mold M is also much lower than that of a metal mold. Moreover, since a mold is directly taken from the original model 1, the skin material 2, that is, the mold M, can be manufactured with an accurate shape corresponding to the outer shape of the original model 1. moreover,
In the case of molds, it is technically very difficult to manufacture molds with very large shapes, and the cost is also high, but with the skin material 2 of this invention, the above constraints can be avoided. There is no problem at all, and even fairly large products can be manufactured without any problems and at a relatively low cost.

If only a thin skin material 2 is used, it will be inferior in rigidity and strength, and there is a risk that it will deform due to the foaming pressure in the foam molding process. Since the reinforcement is provided, the above deformation can be reliably prevented, and the finishing accuracy of the molded product P is as accurate as that of conventional molds. In addition, regarding the durability of the mold M, if the number of molded products P produced is relatively small, even if the mold M uses the skin material 2 of this invention, there will be no problem and it will be sufficient. It can be used practically.

Next, the mold M formed as described above
After inserting a filling nozzle directly into the mold cavity C from the outside of the mold M to fill the raw material resin particles, the heating probe 6 is further inserted into the mold cavity C to blow out a heating medium such as steam. By performing so-called probe molding, in which the molded product P is produced by heating and fusing resin particles, it is possible to attach the attachment mechanism to the molding machine, the raw material filler, etc., like a conventional mold. No need to install. Therefore, even with the mold M of this invention, which is somewhat inferior in strength and precision in external shape and difficult to form a complicated attachment mechanism, etc. compared to a mold, it is possible to perform foam molding satisfactorily. It is something.

Furthermore, since complicated equipment such as a molding machine is completely unnecessary and the molding work is easy, there is no longer any restriction on the size of the molded product P due to the capacity of the molding machine, and large molded products P can be formed freely. become.

For example, a molded product P made by the foam molding method using the mold M of this invention has a length of 4000 mm and a width of 4000 mm.
We were able to produce core material for surfboards that was 600 mm long and 160 mm thick.

As mentioned above, according to the mold M of this invention, it is possible to manufacture large molded products P extremely easily and efficiently, which was difficult in the past, and especially for molded products P whose production volume is relatively small. In some cases, it is very effective and can greatly contribute to expanding the use and demand for foam molding.

[Brief explanation of the drawing]

The figure shows an example of this invention.
The figure is a sectional view, the second figure is a perspective view of the main part during molding, and the third figure is a cross-sectional view.
The figure is a schematic plan view, FIG. 4 is a sectional view showing the manufacture of the skin material, and FIG. 5 is a sectional view of the manufactured foam molded product. 1...Prototype model, 2...Skin material, 3...Rigid frame, 4...Filling material, 5...Cooling piping, 6...
...heating probe, M...molding mold, P...molded product.

Claims (1)

[Claims for Utility Model Registration] 1. A mold cavity filled with raw material particles made of an expandable thermoplastic resin and in which the filled raw material particles are heated and fused to form a predetermined shape;
This mold cavity is formed in layers along the outer surface of the original model, and is divided into two parts.
It is divided by FRP resin skin materials, and the back of each skin material is integrally formed with a reinforcing material consisting of a cross-shaped rigid frame and a filler filled between the rigid frames. A mold for foam molding. 2. The mold for foam molding according to claim 1 of the above-mentioned utility model registration, wherein a cooling pipe is arranged on the back side of the skin material.