JPS6240950A - Molding method - Google Patents

Abstract

PURPOSE:To produce a molding having no defects such as recesses by the stagnation of gas by bringing a shielding film having many vent pores into tight contact with a master pattern member and packing a granular packing material to the outside thereof in a molding flask then attracting the shielding film toward the granular packing material side by a negative pressure, parting the master pattern member, pouring a product material into the cavity made after parting and curing the material. CONSTITUTION:The PE shielding film 2 having the many vent pores is brought into tight contact with the surface of the master pattern member 1 formed of a wooden pattern, etc. Such member is held in place between a pair of the upper and lower molding flasks 3 and 3 and the granular packing material 6 is packed into the flasks 3. The entire part is tentatively fixed by a retaining flask 4 an the inside of the flask is evacuated to the reduced pressure through pipes 5 provided to the flasks 3 to compact the packing material. The upper and lower flasks are then separated and after the master pattern member 1 is taken out, both flasks 3, 3 are joined. An expandable resin liquid 9 such as polyurethane stock is put into the cavity 8 corresponding to the master pattern member and is cured to fashion a polyurethane molding 10. The gas generated in this stage is vented through the vent pores of the shielding film. The product 10 having no defects by the stagnation of the gas is thus produced at a good yield.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention includes a method in which a shielding film is closely attached to a prototype member, and a filling material made of particulate matter is filled on the opposite side of the shielding film with respect to the prototype member. This invention relates to a molding method in which a negative pressure is applied to the filling material side so that the shielding film is adsorbed to the filling material side, and then the prototype member is released from the mold, and then the product material is flowed into the cavity and cured.

[Prior art] Conventional molding methods use a mold that has already been formed by molding a solid object made of metal, resin, etc.
The structure has been such that a predetermined molded product is obtained by pouring metal into the mold.

With the molding method described above, not only does it take time and effort to manufacture the mold, it also takes time and effort to take out the product, and since the mold is made of solid material, it can be used for a wide variety of molds. Since molds need to be kept on hand, storing them is troublesome.

Therefore, for example, as disclosed in Japanese Patent Publication No. 50-8409, regardless of the mold, particulate matter is solidified by negative pressure suction, and the solidification is released by releasing the negative pressure suction. A casting method has been proposed that takes advantage of this fact to easily obtain cast products.

This casting method involves placing a shielding member in close contact with a prototype member, filling the outer periphery of the prototype member with this shielding member with particulate matter, and applying negative pressure to the particulate matter side. This method has the steps of adsorbing the product material to the side, then releasing the thickened mold member to form a cavity, and flowing the product material into the cavity and curing it.

[Problems to be Solved by the Invention] However, in the casting method disclosed in Publication No. 2, a resin film or the like having no air permeability is used as the shielding film.

The use of such a shielding film that does not have air permeability causes the following problems.

In other words, when producing an integral cover that covers an on-off valve or its piping for heat insulation, it is common to use foamed resin for the heat insulation, but in this case, for example, polyurethane resin is polymerized. 2 when obtained by reaction
Freon gas is generated in the temperature range of 0 to 33°C, and this Freon gas is discharged to the outside of the foamed cells.

As a result, these freon gases accumulate between the foamed product material and the shielding membrane, resulting in small air bubbles or depressions remaining at the outer periphery of the product.

Such air bubbles or dents are undesirable because they may result in defective products or reduce product value.

The present invention has been made in view of the above problems, and aims to eliminate defective products and increase product value by effectively suppressing the generation of bubbles or dents.

[Means for Solving the Problems] In order to solve the above problems, the molding method of the present invention is to provide a molding method in which a shielding film is closely attached to a prototype member, and a particulate matter is removed from the shielding film on the side opposite to the prototype member. The filling material was filled with a negative pressure on the filling material side to adsorb the shielding film to the filling material side, and then the prototype member was released and the product material was allowed to flow into the cavity and harden. In the molding method, the product material is a foamable resin, and a large number of gas vent holes are formed in the shielding film.

[Function] According to the present invention having the above-mentioned configuration, gas generated during foaming, residual air, etc. are removed from the product material side through the shielding film by the gas vent holes provided in the shielding film.

[Example] An example of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a prototype member, and for ease of understanding, a spherical member is shown here as an example.

The prototype member 1 may be formed from a wooden mold, clay, styrene, or the like, or may be used as it is.

2.2 is a shielding film, which is made of polyester, aluminum foil, polyethylene, or the like, and is composed of two resin films.

These two shielding films 2.2 are placed facing each other with the prototype member 1 in between, and then suction is applied between the two shielding films 2.2 while being heated to about lo o'c as shown by the arrow in FIG. , whereby the shielding film 2.2 is brought into close contact with the prototype member l.

In this case, it can also be carried out at room temperature.

The prototype member 1 with the shielding film 2.2 in close contact with it is held between two rows of upper and lower molding frames 3.3, and the prototype member 1 is positioned within the definition molding frames 3,3.

Here, 4 indicates a holding frame, and 5 is a suction pipe with a filter, which is provided in each molding frame 3, 3, and the suction pipe 5 is connected to a suction pump (not shown) via a valve (not shown). is connected.

As mentioned above, while holding the prototype member l with the shielding film 2,
A filling material 6 made of particulate matter is flowed into each molding frame 3, 3 using a suction pipe 5, and filled into the holding frame 4.
Temporarily fasten the whole thing.

In this case, vibration can also be applied.

In this state, negative pressure is sucked into the molding frames 3, 3 through the suction pipe 5 as shown by the arrow to reduce the pressure, and the filling material 6 is solidified by the pressure difference with the outside atmospheric pressure. At this time, the negative pressure suction between both shielding membranes 2.2 is released.

As a result, while maintaining the negative pressure suction state, as shown in FIG. 4, the molding frames 3, 3 below ``1'' are separated.

At this time, the molding frames 3, 3 are closed with a closing cover 7.7 made of rubber or polyethylene film or the like.

As a result of this separation, the original model member 1 is taken out individually.

After that, as shown in Fig. 5, both molding frames 3.3 are
1- Recombine while maintaining the negative pressure suction state.

By this combination, a spherical cavity 8 corresponding to the prototype member 1 (FIG. 1) is formed, and within the cavity 8 both shielding films 2, 2
Product material (19) is supplied throughout the process.

This product material 9 is a foamable resin liquid, and for example, when a polyurethane stock solution is introduced, a polymerization reaction occurs in the cavity 8, and as the material hardens, a polyurethane product 10 is obtained as shown in FIG.

At that time, Freon gas is generated from each bubble at 20 to 33°C, but since this Freon gas flows out to the outside, in this invention, gas vent holes (not shown) are formed in the shielding films 2, 2. put.

The gas vent holes are, for example, about 0.01 mm in diameter and arranged at intervals of about 10 mm.

Due to the presence of these gas vent holes, even if the Freon gas generated above flows out and attempts to accumulate in the shielding film 2, it is removed to the outside and is discharged to the outside of the molding frames 3, 3 by suction. This also includes residual air.

In addition, if the product 10 needs to be molded in the same way next time, as shown in FIG. For example, as shown in FIG. 8, by releasing the negative pressure suction through the suction pipe 5 and removing the filling material 6, the product 10 is taken out at the same time, and then the necessary scraping etc. are performed to make it into a product. Perform the finishing touches.

As described above, since foaming is performed using the shielding film 2.2 in which gas vent holes are formed, no air bubbles or depressions remain in the product 1O, thereby increasing the product value.

In addition, the above gas vent hole has a ventilation effect during suction, but
Needless to say, the negative pressure suction capacity is set to such an extent that the filling material can be solidified against the ventilation effect.

[Effects of the Invention] As described above, according to the present invention, gases generated during foaming, residual air, etc. are removed from the product material side through the shielding film by the gas vent holes provided in the shielding film. This structure effectively suppresses the generation of bubbles or dents, which not only prevents defective products but also increases product value.

[Brief Description of the Drawings] Fig. 1 is an explanatory diagram showing a process of wrapping a prototype member with a shielding film, which is an embodiment of the present invention, and Fig. 2 is an explanatory diagram showing a process of bringing the shielding film into close contact with the prototype member by heating. Figure 3 is a sectional view showing the process of holding the prototype member with a shielding film in the molding frame and filling it with a filler material, and then suctioning negative pressure, and Figure 4 is a sectional view showing the process of releasing the prototype member from the mold. 5 is a sectional view showing the process of introducing the product material, FIG. 6 is a sectional view showing the process of reacting and hardening the product material, and FIG. 7 is a sectional view showing the process of taking out the product while suctioning negative pressure. FIG. 8 is a cross-sectional view showing the process of taking out the product together with the filling material. DESCRIPTION OF SYMBOLS 1... Prototype member, 2... Shielding film, 6... Filling material, 8... Cavity, 9... Product material. Figure 1 Figure 2 ↓ Figure 3 Figure 4

Claims (1)

[Claims] (1) A shielding film is closely attached to the prototype member, and the opposite side of the shielding film to the prototype member is filled with a filling material made of particulate matter, and the filling material side is subjected to negative pressure, and the shielding film is replaced with the filling material. In a molding method in which the product material is adsorbed to the side and then released from the mold, the product material flows into the cavity and hardens.
A molding method characterized in that the product material is a foamable resin and a large number of gas vent holes are formed in the shielding film.