JPS594296B2 - Injection molding method using a simple mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection molding method using a simple mold made of resin.

5. When making resin products using the injection molding method, there are two types: trial production and mass production.

In order to make a mold for mass production, there are various issues such as the characteristics of the resin used for injection molding and the shape of the product, so it is necessary to make a prototype mold and investigate the product shape and the characteristics of the resin. However, in the past, prototype molds were processed and formed from metal, which required time to manufacture and extremely expensive materials. In general, simple molds made of synthetic resin have poor thermal conductivity, so the heat of the molten thermoplastic resin injected during molding is transmitted to the simple mold, and the temperature increases due to the injection pressure, further accumulating heat. There were drawbacks such as the simple mold cracking, the product becoming difficult to peel off from the mold after molding, or the products adhering to each other and not peeling off, resulting in damage to the mold. This invention eliminates the drawbacks of the conventional method, and provides a simple mold made of resin that is easy to manufacture and inexpensive in material cost, as well as a metal block with good thermal conductivity and a cooling pipe for water circulation. The purpose is to perform molding operations while cooling the simple mold 25 through the synergistic effect of cooling while inserting and forcibly circulating cooling water, and cooling due to heat diffusion of the metal block. An embodiment of the present invention will be described with reference to the drawings. 1 is a male mold for making a molded product, and 2 is a paired female mold.

First, to make the simple male mold 11, on the inner surface of the female mold 2,
A clay mold 3 is formed by applying clay a little thicker than the thickness of the finished product, and inside this clay mold 3 there is a cooling pipe 4 which will be described later.
Protrusions 4, 4 are provided to form grooves 11' for accommodating 0 (FIG. 3). Next, plaster is poured into the clay mold 3 to form a mold 5 for casting 35 metal blocks (FIG. 4). Reference numeral 6 denotes a sand mold in which sand for molding is housed and hardened in a frame plate 8 surrounding the upper surface of the bottom plate T. The temporary mold is housed in the upper center of this sand mold 6, and the surface shape of the temporary mold is determined. After inverting the mold into a sand mold, the plaster is taken out to form a housing part 9 (FIG. 5).

Next, aluminum or other known metal having good thermal conductivity is poured into the housing part 9 to form a first metal plotter 10 which is slightly smaller in size along the shape of the male mold 1 (FIG. 6).
A large number of grooves 11', 11' for accommodating cooling pipes 40 are provided on the surface of the first metal block 10.
Next, a first metal block 10 is placed on the upper center surface of the mounting plate 12.
is fixed by known means, and this first metal block 10
The cooling pipes 40 and 40 are housed in the grooves 1'' and 11' provided on the surface of the male mold 1, respectively.Next, plaster is applied to the surface of the male mold 1, and a plaster mold 14 having an inverted mold 13 on the inner surface is formed. , and is attached to the outside of the first metal block 10 at a constant interval 15 (FIG. 7).The resin liquid is injected from the sprue 16 provided in this plaster mold 14, as shown in the upper part of FIG. After forming the simple male mold 11, the plaster mold 14 is removed.Next, the case of forming the simple female mold 3r will be explained.
A clay mold 22 is formed by applying clay to the surface of the male mold 1 to a thickness slightly thicker than that of the finished product.

Projections 23, 23 are formed on the surface of this temporary mold to provide grooves for accommodating cooling pipes 4'' (described later).
Figure 8). A frame plate 24 is attached around the flat surface of this male mold 1,
Plaster is poured into this frame to form a temporary mold 25 (FIG. 9). Next, a frame 27 is provided around the upper surface of the bottom plate 26, and casting sand for casting the second metal block is housed and hardened within this frame 27, and the temporary mold 25 made of plaster is housed in the center part. After forming a sand mold 29 having a housing part 28 with the surface of the temporary mold reversed, the temporary mold 25 is removed (FIG. 10).
. Next, a metal with good thermal conductivity is poured into the housing portion 28 of the sand mold 29 to form a second metal block 30 (FIG. 11). Furthermore, after this second metal block 30 is accommodated in the mounting body 31, cooling pipes 4 are inserted into grooves 32 and 32' provided on the surface of the second metal block 30, respectively.
The inverted mold 34 of the female mold 2 made of plaster or the like is attached to the center of the lower surface of the mounting plate 33.
A gap 35 is provided between the mold 4 and the second metal block 30 (FIG. 12), and resin is injected from the casting port 36 provided in the inverted mold 34 to form the second metal block shown in the lower part of FIG. A simple female mold 3r integral with 30 is formed. In addition, metal block 10
, 30, the cooling pipe 4 is installed in the groove 11'32 provided on the surface of the cooling pipe 4.
0,4'' and when molding the simple molds 11, 37 with resin on the surface of the metal bucket, the resin liquid also fills the gap between the concave groove and the cooling pipe and fixes them together. do.

In this case, since the cooling pipe is in contact with a metal block with good thermal conductivity, there is a difference in thermal expansion between the resin forming the simple mold and the steel pipe forming the cooling pipe. Because it is diffused by metal blocks,
No peeling phenomenon occurs. The simple male mold 11 and the simple female mold 3r produced in the above steps are clamped as shown in FIG. 2 with the same gap as the dimensions of the finished product, that is, the molding cavity 39, and the respective cooling pipes 40, 4 Molding is performed by injecting high temperature and high pressure resin into the gap, that is, the mold cavity 39, while forcibly circulating cooling water from the outside.

As described above, the present invention provides a cooling means that forcibly circulates cooling water from the outside through a cooling pipe to a simple type made of resin with poor thermal conductivity, and a simple reinforcing member that has good thermal conductivity. If injection molding is performed while the simple mold is cooled by the synergistic effect with the cooling means of heat diffusion by the metal block, the simple mold will not deteriorate even if injection molding is performed continuously, and will maintain its excellent properties. In addition to being able to obtain a molded product, the cooling pipe that sends cooling water is not directly buried in a simple resin mold, but is housed in a groove provided on the surface of the metal block so that the cooling pipe and the metal block are in contact with each other. This prevents the peeling phenomenon between the simple resin mold and the cooling pipe.
It has the advantageous feature of increasing the durability of a simple type.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the relationship between a male mold and a female mold in conventional injection molding, Fig. 2 is a sectional view showing an embodiment of the present invention, and Figs. 3 to 6 show the process of manufacturing a simple male mold. Figure 3 is a cross-sectional view of a clay mold formed by applying clay inside the female mold, Figure 4 is a cross-sectional view of a temporary mold made of plaster inside the clay mold, and Figure 5 is a cross-sectional view of a clay mold formed inside the clay mold. Fig. 6 is a cross-sectional view of the state in which a sand mold is made using a temporary mold. Fig. 6 is a sectional view of the state in which metal is poured into the sand mold to form the first metal block. Fig. A cross-sectional view of the plaster mold installed, Figures 8 to 12 show the process of manufacturing a simple female mold, and Figure 8 is a cross-sectional view of the male mold coated with clay to make a clay mold. Figure 9 is a cross-sectional view of a temporary mold created using this clay mold, Figure 10 is a cross-sectional view of a mold being formed using the temporary mold, and Figure 11 is a cross-sectional view of a second metal block manufactured. Figure 12 is a cross-sectional view of a simple female mold manufactured using the second metal block and an inverted female mold, Figure 13 is the relationship between the concave groove of the metal block, the pipe, and the simple mold. FIG. 1 is a male type, 2 is a female type, 10 and 30 are metal blocks, 11
11', 32 are concave grooves, 37...simple female mold, 39 is a molded cavity, and 40, 407 are cooling pipes.

Claims (1)

[Claims] 1. A step of providing a plurality of grooves on the surfaces of a pair of metal blocks with good thermal conductivity formed approximately along the surface shapes of the male and female molds, and a step of accommodating cooling pipes in each of the grooves. and a step of integrally forming a simple male mold and a simple female mold made of resin with male and female surface shapes on the surface of each metal block, and a pair of metal blocks and the simple male mold respectively formed integrally. and clamping a simple female mold, and the simple mold is characterized in that molding is carried out by injecting a resin liquid into the molding cavity while forcibly circulating cooling water from the outside through the cooling pipe. Injection molding method.