JPS58211408A - Forming device of product made of thermoplastic resin sheet - Google Patents

Abstract

PURPOSE:To form a formed sheet with projections efficiently by a method wherein the projection tops of opposing metal forces are cooled down to the temperature so that a thermoplastic resin sheet to be formed may not be flown away while the specified depth and interval of the mutual projections may be maintained. CONSTITUTION:A top force A and a bottom force A' are provided with multiple projections 2, 2' on the positions equivalent to the grid-like points of intersection on a substrate 1 and the surfaces thereof. The projections 2, 2' are pillar-shaped bodies with flat square tops 3, 3'. The top bottom forces A, A' are arranged with opposing projections 2, 2' and one force A is arranged so that the projections 2 thereof may be inserted into almost central positions of four projections 2' of the other force A'. Assuming the depth of the projections 2 inserted between the projections 2', 2' of the other force A' to be 2H, the following expression shall be satisfied, i.e. 2W1/(W1+W2)>=1/3.2H/(W1+W2)<2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molding apparatus for plastically deforming a thermoplastic resin sheet to form a sheet molded article. The purpose is to propose a molding device that can efficiently mold a molded article in which truncated cone-shaped hollow convex portions alternately protrude on both sides of a sheet.

Conventionally, thermoplastic resin sheets (hereinafter simply referred to as sheets)
When forming a hollow convex portion in a mold, a mold matching the dimensions of the convex portion is prepared, and the raw material sheet is plastically deformed and molded in contact with this mold.

Therefore, one mold is required for one type of convex shape, resulting in a large mold cost. In particular, in the case of a molded product having a large number of hollow convex portions on both sides of the sheet, the mold shape is complicated and the cost of the mold is even greater.

This invention was made in view of the above circumstances, and the gist thereof is to provide a mold 2 having a plurality of protruding columnar protrusions each having a flat top surface.
At least one of the molds is arranged to be movable in the height direction of the projections so that the protrusions of one mold can be inserted into the center between the projections of the other mold, and the two molds are at least When the thermoplastic resin sheet on which the top of the protrusion is to be molded is cooled to a temperature at which it does not substantially flow, and one protrusion is inserted between the other protrusions, the side surfaces of the other protrusion located on both sides of one protrusion W! , the width of the top surface of the protrusion in the direction of the side spacing is 2H, the depth into which the W11 protrusion enters.
This is a molding apparatus for a thermoplastic resin sheet molded article characterized in that the following relationship holds true.

FIG. 1 shows an example of an embodiment of this device, in which the upper mold A1
It has a lower mold A', and each mold is shown in FIGS. 2 and 3.
As shown in the figure, a plurality of protrusions 2.2' are provided at positions corresponding to every other grid intersection of the substrate 1 and its surface. The top surfaces 3, 3' of these protrusions 2, 21 are square (-side length W
l) is a planar columnar body. These upper and lower molds A, A/ are arranged facing each other with their protrusions 2゜2' facing each other, as shown in Fig. 4. At least one of the molds A is disposed so as to be movable in the height direction of the projection 2 so as to fit into the approximately central position of the projection 2I. In addition, cooling water pipes (not shown) are embedded in the projections 2, 2/ of the upper and lower molds A, A', and at least the tops of the projections 2.2' are substantially free from the sheet to be molded. It is kept at a temperature that does not flow.

When the two molds A and A/ are close to each other, both protrusions 2.2' alternately occupy grid intersection positions, and the sides of the other protrusions 2/, 2/ located on both sides of one protrusion 2. 4
/, 4/ interval W1, one protrusion 2 is the other protrusion 2t,
2 is inserted into the space between 2H and 2H. When forming a sheet molded body using this device, the raw material sheet B made of thermoplastic resin is heated in advance to make it fluid and thermoformable. As shown in Figure 5, upper and lower molds A
, A/ send it between.

In this state, the upper and lower molds A and A/ are brought close to each other so as to sandwich the sheet B between them. First, the top surfaces 3.3' of the protrusions 2, 2I are in contact with the sheet B, but since the temperature of the top surface is such that the sheet B does not substantially flow, the top surface 3.3' is in contact with the top surface 3.3'. Sheet B solidifies on cooling and stops flowing. Therefore, when the molds A and A/ are brought closer together and the protrusion 2 of one is inserted between the protrusions 2' of the other, the sheet B is fixed at the top surface of the protrusion 2.2', and the sheet between them is is extended in the vertical direction without contacting the side surfaces of the protrusions 2 and 2'.

The molded product obtained by bringing the molds A and A/ close together to a penetration depth of 2H, molding and cooling, is as shown in FIGS. 6 and 7. That is, hollow truncated quadrangular pyramidal convex portions 5, 5' protrude alternately on both the front and back sides of the sheet B, and the top surfaces 6, 6' of the convex portions 5.5/2 form a square plane with side length Wl. None, the heights of the top surfaces 6.6I from the three surfaces of the sheet are each ■, and the upper and lower top surfaces 6.6' are aligned on one plane. Convex portions 5, 5/ of the convex sheet molded product are 1/W, ≧+, H/wa
It becomes a truncated regular square pyramid with < 2. In addition, the convex portion 5.5
The top surfaces 6, 6I of / are in contact with the top surface (4) 5.5' of the mold protrusion 2.2/ and are not stretched, so the thickness 1° is equal to the thickness t2 of the stretched side surfaces 7, 7' of the protrusion. compared to 1, >12
becomes.

This sheet molded product is bulky and at the same time has relatively wide top surfaces on both the front and back surfaces, so it can have high compressive strength. Furthermore, it is lightweight and has excellent heat insulation performance because it has many independent voids partitioned by convex parts. In addition, the convex portions 5 and the convex portions 5 adjacent to each other on both the front and back sides are
/ are connected in a curved manner as shown in FIG. 6, and since the curved ribs on both the front and back sides face each other at right angles, the bending strength can be improved. Moreover, since this curved rib is formed in the three-dimensional direction ξ from the convex portion 5 of the molded body, the compressive strength of the convex portion itself is increased. Note that fine irregularities are provided on the flat projection top surfaces 3 and 3' of the molds A and A/, and fine irregularities are formed on the convex portions 5.5/top surfaces 6.6/ of the resulting sheet molded body and bonded. It is also possible to improve the strength.

The convex portions 5,5' of the sheet molded product obtained are 0.2, ≦2, that is, the height of the convex portions 5,5' is more than twice the length of the base to the side, and the elongation during molding is poor. Moreover, it becomes extremely difficult to release the molded product from the mold, and at the same time, the convex portions of the sheet molded product obtained are elongated and thin, and the side surface thickness becomes thin, which is undesirable because it tends to buckle and lower the compressive strength. Also, protrusion 2,
The convex portions 5 and 5' with 2I are '/wa<+, that is, the top surface-side length is less than 10 of the bottom side length, and the ratio of the total area of the top surface to the entire surface of the molded body decreases, and the panel core material and When used as a cushioning material, the compressive strength and the adhesion area with the surface material decrease, which is undesirable. Normally the area of the top surface of the protrusion 5.3/ is 0.09
m~25d, protrusion crowd depth 2H is about 5~100 dragons.

The sheets that can be molded using this molding device are:
Hard vinyl chloride, polystyrene, high density polyethylene,
Polypropylene, nylon 6.66, polyester, A
Although it is made of a hard thermoplastic resin such as BS resin (acrylonitrile, phtadiene, styrene copolymer), a sheet of soft thermoplastic resin such as soft polyvinyl chloride or low density polyethylene can also be used as a raw material. The hard resin sheet molding is suitable for use as a panel core material, and the soft resin sheet molding is suitable for use as a cushioning material. However, its uses are not limited to the above-mentioned uses. The thickness of the sheet used as a raw material is 100 to 1000μ.

The mold projections of the forming apparatus must be cooled, at least at the top, to a temperature at which the sheet to be formed will not substantially flow. This temperature is generally below the melting or softening point of the sheet. In order to cool the mold to this temperature, conventional means such as embedding a water cooling pipe in the protrusion and blowing cooling air onto the mold are used. The shapes of the protrusions can be freely set, such as cylinders and polygonal prisms in addition to the above-mentioned regular square prisms, to form a sheet molded body (7) in which hollow protrusions such as truncated cones and truncated polygonal pyramids alternately protrude. I can do it.

The present invention is as described above, and a sheet molded body having hollow convex portions protruding from both the front and back sides can be molded using two molds each having a large number of protruding columnar protrusions. Therefore,
Compared to conventional molding that uses a mold that matches the shape of the convex part, the structure is simpler and the cost per piece is lower, and the height of the convex part can be adjusted freely by adjusting the penetration depth of the two molds. Since a wide variety of molded objects can be molded by selecting the mold, the burden of counterfeit mold costs is reduced.

Furthermore, the resulting sheet molded product can have increased compressive strength and adhesive strength, and is suitable for use as a panel core material, cushioning material, etc.

Example 1 Mold 2 in which a plurality of square prism protrusions made of brass with a top surface of 5 dragons on each side and a height of 60 mm were protruded from an aluminum plate with a thickness of 101111 and arranged at a pitch of 25111 at intersections in a grid pattern. The pieces were placed facing each other on the upper and lower sides of the press section of the radiation heating molding machine. Attach the mold protrusion group installed on the upper side to the lower side (8).
In other words, the protrusion group shown in Fig. 2 is placed on the upper side, the protrusion group shown in Fig. 3 is placed on the lower side, and the upper and lower protrusion groups are positioned so as to alternately occupy grid intersection positions as shown in Fig. 4. In order to prevent the temperature from rising above 20° C., the molding device was constructed by embedding a water cooling pipe for circulating cooling water inside the protrusion.

On the other hand, a 0.5-thick sheet of hard polyvinyl chloride is heated with radiant heat to the appropriate molding temperature, quickly fed between the upper and lower molds, the upper and lower molds are brought close together, and molded by being inserted between the upper and lower protrusions. After the sheet had cooled, the upper and lower molds were separated and the sheet molded product was taken out. As a result, it was possible to obtain a molded body of a hard polyvinyl chloride sheet having a thickness of 0.5131 having square truncated hollow convex portions with a side length of 5 squares on both the front and back surfaces.

Also, the speed at which the sheet is inserted is 20 yst.
Molding was possible at tr /sea or higher.

I tried to create various thicknesses of molded products by suitably adjusting the depth of the sandwiching, but it was impossible to create molded products of 50 or more thickness because the side walls became too thin during molding.

When the molded bodies obtained under these conditions were examined in detail, it was found that the thickness of the top surface of the hollow convex portion was relatively 1 thicker than the thickness of the side wall in each case. Similarly, similar results were obtained for impact-resistant polystyrene sheets and polypropylene sheets, as shown in Table 1.
V'Ws is 0.4.

The compressive strength of the obtained molded body was measured by the method of JIS Z 0234, and t OK 176 m2 or more was evaluated as ○.

Table 1 Table 1 (Continued) Comparative Example In a molding device similar to Example 1, only the protrusions"/wm
An experiment similar to the example was conducted using a square prism (4 squares or less on each side) with <10.

The compressive strength was measured using the test method and was as shown in Table 2.

The evaluation of compressive strength is the same as in Example 1.

(11)

[Brief explanation of drawings]

The drawings show examples of embodiments of the invention, and the first
The figures are longitudinal sectional views of the mold part of this device, Figures 2 and 3,
FIG. 4 is a schematic plan view showing the positions of the protrusions when the upper mold, lower mold, and upper and lower molds are brought close to each other, FIG.
7 are a perspective view and a longitudinal sectional view of the obtained sheet molded body, respectively. A... Upper mold A/... Lower mold, B... C (12) 1, 1... Substrate, 2, 2'... Protrusion, 5.5'... Top surface, 4, 4'・・Side surface, 5,5′・・Protrusion, 6,6I・
・Top surface of the protrusion, 7.7'...Side surface of the protrusion, W□...Width of the top surface of the protrusion and protrusion, Ws...Width of the bottom of the protrusion, "R"...Distance between the side surfaces of the protrusion 1°・7"5 )yhhR8-11,, 1,...Thickness of the convex mold surface and side surface.

Claims (1)

[Claims] (1) Mold 2 with a plurality of protruding columnar projections with a flat top surface
At least one of the molds is arranged so that it can move in the height direction of the projections so that the protrusions of one mold face each other and the projections of one mold fit into the center position between the projections of the other mold, and The mold has at least the top of the protrusion cooled to a temperature at which the thermoplastic resin sheet to be molded does not substantially flow;
When one protrusion is inserted between the other protrusions, the distance between the sides of the other protrusion located on both sides of one protrusion is "II"
A molding device for a thermoplastic resin sheet molded body, characterized in that the following relationship holds true, where Wl is the width of the top surface of the protrusion in the direction of the side spacing, and 2H is the depth into which the protrusion enters.