JPS637932B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a molding method for molding Styrofoam using a bead method using a block molding machine, and a mold used therein.By using the method of the present invention and the mold, the cooling and cooling time during molding can be greatly increased. It is characterized by being able to shorten the molding process to improve molding productivity. The present invention provides (1) a block molding method that uses a block molding machine with a convex mold surface to shorten the cooling and cooling time in block molding of expanded polystyrene using the bead method; (2) A bead-method block molding mold for polystyrene foam with a convex mold surface. In the present invention, the convex shape of the mold surface means the convex shape of the surface when viewed from the product chamber side of the mold, that is, from the intersection of the x and y axes in FIG. When making the mold surface convex, the purpose is best achieved if the convex shape of the mold is determined by subtracting the allowable bulge value for the product from the bulge value of the product at the desired mold release pressure. Can be done. Further, in order to form and support the convex surface of the mold surface, it is preferable to support the mold with a support having a height corresponding to the convex surface. The usual method for block molding is to fill a mold with pre-expanded grains, preheat with steam (also called mold heating), heat on one side, heat on both sides, cool the molded product, and then cool it. The mold is being removed from the mold. Currently, the molds used in block molding machines generally have dimensions of 1840 mm x 925 mm x 415 mm and are surrounded by straight flat plates. Table 1 shows an example of molding using a commonly used mold, that is, a straight plate mold.

【table】

[Table] As shown in Table 1, the total molding time is 1860 seconds, of which cooling is 1500 seconds, accounting for 80% of the total, and this part is the longest, so if this can be shortened, productivity will increase. It turns out that it is most effective. However, when the molded product is removed after shortening the cooling time, the surface pressure is high because expansion pressure remains inside the molded product, and as a result, the molded product has a large rear bulge. As a result, the following three disadvantages arise. (1) The molded product swells and does not have a good appearance. (2) When cutting and straightening the outer skin of the molded product, it is difficult to set it on a cutting machine.
(3) When slicing a molded body to make a large board, the outer skin is discarded, resulting in a large amount of cutting loss. For the above-mentioned reasons, the surface pressure that is normally applied during mold release is a compromise between the conflicting demands of reducing the back bulge and shortening the cooling and cooling time to increase economic efficiency. generally as
It is 0.05-0.1Kg/ ^cm2 . These phenomena become clear from FIG. 1, which is an example showing the relationship between the surface pressure at the time of mold release, the swelling value after mold release, and the cooling and cooling time. FIG. 1 shows that the swelling value increases if the cooling and cooling time is shortened. However, even in the case of 0.05 to 0.1 Kg/cm ² , there is swelling. The measurement method for the bulge is as shown in Figure 2. Centering on the origin of the x, y, and z axes, divide the bulge into 100 mm intervals in the y direction and 50 mm in the z direction.
This point is used as a measurement point and x−x _nio is measured (x _nio is the minimum x value). Figure 3 shows one of the surface convex molds of the present invention.
An example cross-sectional view is shown. In order to solve the above-mentioned disadvantage of bulging, if the mold surface is corrected to a convex shape in advance so that it has the same shape as the mold release pressure of 0.05Kg/ ^cm2 , the mold release pressure
Even if the weight is 0.05Kg/cm ² or more, an equivalent molded product can be obtained. Next, a method for correcting the mold convexity will be described. In order to correct the mold convexity, it is necessary to measure the bulge state of the molded product. Under the molding operation conditions shown in Table 1, the mold release pressure is (1) 0.05Kg/cm ² and (2)
Tables 2 and 3 show the measurement results of the swelling value at each point of each molded product after molding at 0.2 Kg/cm ² . In each of the above cases, each ridgeline was a straight line, the xy side surface and the zx side surface were horizontal surfaces, and only the yz side surface was convex. In addition, since the bulge values at symmetrical positions from each axis show almost the same value, only one side was measured. However, if the mold release pressure is 0.3 Kg/cm ² , each side of the molded product is convex, creating a so-called daruma shape and unable to stand on its own, which is practically impossible.

【table】

【table】

[Table] The desired shape of the mold with a convex surface can be obtained by subtracting the bulge value in Table 2 from the bulge value at each point in Table 3 ^. Even in the case of 0.05 Kg/cm ² of mold release pressure, a molded product with the same shape can be obtained even if the cooling and standing time is shortened by 40%. As for how to give a given curvature to a mold, it can be easily manufactured by the following method. Conventionally, the sheet metal that constitutes a normal mold used on a flat surface is, for example, made of aluminum and has a thickness of 8 to 12 mm, and the method of mounting this mold is to support it with a long and thin plate as a support and hold it down with bolts. . If a mold with a complex convex surface used in the present invention is to be manufactured by a conventional method, in order to embody a given curvature, the above-mentioned elongated plate is moved along the y and z axes shown in FIG. It is necessary to cut it so that it has a slope so that the curvature appears in the direction, but this is very time-consuming and difficult due to the relationship with the mounting position. Therefore, in order to improve this point, it is more preferable to use a support column having a height corresponding to the above-mentioned curvature instead of an elongated plate as a support. For example, about 20mm in diameter
By making a cylinder of φ and arranging it at a pitch of 100 to 200 mm with a height that gives it a curvature, and holding the mold on top of this with bolts, the necessary curvature can be obtained and it can be manufactured industrially and efficiently. There was found. The support pillar is not limited to a cylindrical shape, but can be a square pillar or a three-sided pillar.
It is fine as long as it is a prism or something that can give height.
The spacing and material can also be selected as appropriate. Since the mold has slits or pores as steam and air supply ports, it is easy to bend and create curvature even if the plate is 8 to 12 mm thick. According to the molding method and mold of the present invention, efficient
It is possible to shorten the cooling time.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between mold release pressure, swelling value, and cooling/cooling time, and FIG. Figure 1 is an explanatory perspective view of the molded body, Figure 2-2 is an explanatory diagram showing the bulge and z number of the A ₁ A ₂ A ₃ A ₄ cross section (xz plane), and Figure 2-3 is an explanatory diagram showing the z number.
B ₁ B ₂ B ₃ B _{4Longitudinal} section (x-y plane) bulge and y
It is an explanatory diagram showing numbers. FIG. 3 is a sectional view showing an example of a mold having a convex surface when viewed from the product chamber side of the present invention. 1 in FIG. 1 is a relationship graph between mold release pressure and swelling value, and 2 in FIG. 1 is a relationship graph between mold release pressure and cooling and cooling time.

Claims (1)

[Scope of Claims] 1. A block molding method for block molding expanded polystyrene using the bead method, characterized in that the mold of the block molding machine is molded with a mold whose surface is convex when viewed from the product chamber side. . 2 From the swelling value of the product at the set mold release pressure,
2. The block molding method according to claim 1, wherein a value obtained by subtracting the bulge value allowable for the product is adopted as the bulge value of the convex shape on the mold surface. 3. A bead method styrofoam block molding mold with a convex surface when viewed from the product chamber side of the mold. 4. The block molding mold according to claim 3, wherein the support for the sheet metal constituting the convex surface of the mold has a height corresponding to the curvature of the convex surface.