JPS5832111B2 - Strain prevention structure of molded corrugated board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molded corrugated cardboard interior material used for the interior of vehicles, ships, houses, etc., and particularly to a structure that can prevent distortion that is likely to occur in the molded corrugated cardboard that is the base material. It is.

Corrugated cardboard interior materials are specially manufactured using relatively strong pulp and adhesive such as thermoplastic resin to enable thermoforming. The cardboard base material is molded into a predetermined shape, and the surface is decorated with decorations if necessary. It is made by laminating skin materials, and has the advantages of being lightweight, heat-insulating, and sound-proofing.

The most common method for producing this corrugated interior material is to heat-form only a flat corrugated cardboard base material in a specified press mold to form a molded corrugated cardboard, and then apply an adhesive sheet such as a hot melt adhesive. This is a method in which a skin material made of vinyl chloride or the like lined with is spread on a molded corrugated board, and then heat-pressed again to adhere the skin material to the surface of the molded corrugated board.

FIG. 1 shows a molded corrugated board 1 used when manufacturing a roof trim for an automobile by such a manufacturing method. A convex portion 2 is provided on the upper side.

Note that the peripheral portion 3 is to be trimmed in a later process.

However, when hot press forming corrugated cardboard in this way, if there is a trapezoidal or step-shaped cross-sectional shape 2' (the upwardly convex portion 2 in FIG. 1) in a part of the cardboard as shown in FIG. , after the completion of thermoforming, especially during the cooling process, the iron part 2'
A problem may occur in which the flat top surface 4 of the disk is bent downward (distorted) as shown by the imaginary line in FIG. 2A.

Particularly in the case of a roof trim as mentioned above, the flat top part occupies the main part of the appearance, and deformation (distortion) of this part will affect the commercial value of the roof trim and the roof h IJ. This will reduce the value of cars that have been modified.

In addition, in order to form such a convex part, in order to prevent wrinkles and tears in the part, the method described in Japanese Patent Laid-Open No. 52-2699 is used.
As described in No. 1, there is a method in which the core of the entire corrugated board is crushed and molded.

However, the strength of the protrusions formed by this method decreases, so as described in the above-mentioned publication, it is effective when used to form relatively small parts such as sun visor storage parts and room lamp mounting parts. However, in the case of the above-mentioned roof trim, the convex portion 2 is large and, therefore, the concave portion appears conspicuously, so it cannot be used.

Considering the causes of such distortion, since the history of corrugated board forming technology is extremely short, we have not yet fully understood the behavior of softened corrugated board during hot press molding or the manner in which its properties change during the subsequent cooling and solidification process. Although it is difficult to provide theoretical support because it cannot be explained, from a phenomenon perspective, as shown in FIG. 2B, the molded corrugated cardboard 1 shown in FIG. is press-formed, and then when the upper die D2 is pulled up, the formed corrugated cardboard 1 temporarily warps upward as shown by the two-dot chain line, a phenomenon opposite to that seen in sheet metal presses (however, the drawings do not show this phenomenon). ), and the top surface 4 is deformed as described above.

Therefore, this deformation is caused by the warping deformation of the entire convex portion 2'.
From the interpretation that it is caused as a result of being applied to the top surface 4 via the rising part 5 and being concentrated there, it follows that if the rising part 5 is made soft and weak, the influence of warp deformation will be absorbed by this rising part. It should not affect the top surface 4.

Based on the above premise, we formed the rising part 5 to be soft, in fact, to make it easily deformable by crushing the core part and reducing its thickness. As expected, the deformation of the top surface 4 did not occur. It was almost completely preventable.

Therefore, an object of the present invention is to deform at least a part of the rising surface of a trapezoidal or step-shaped molded part in a molded corrugated board so that it is easily deformed, thereby deforming the rising surface part so that the deformation is noticeable. An object of the present invention is to provide a distortion prevention structure that can prevent distortion at a top surface.

The present invention will be explained below with reference to embodiments shown in FIGS. 3 to 5.

FIG. 3 is an enlarged view of the trapezoidal part 12 of the molded corrugated board 11, 13 is an upper liner, 14 is a lower liner, and 15 is a core sandwiched between these liners 13 and 14. It is.

Also, the portion 16 extends the flat top surface of the trapezoidal shape to the portion 17.
18 indicates a rising surface portion in an inclined state, and 18 indicates a base surface.

In the present invention, when forming such a trapezoidal part, the base surface part 18 and the top surface part 16 are molded to ensure the same thickness as in the conventional method, but for the rising surface part 17, the mold clearance of the molding die is adjusted. The core 15a is made smaller and the core 15a is crushed to reduce the overall thickness.

Therefore, if such a configuration is adopted for a roof trim as shown in FIGS. 1 and 2, deformation and distortion of the top surface portion, which is easily visible from the outside, can be prevented from becoming dirty.

The rising surface portion is not a very conspicuous portion, and since it is an upright portion, even if the core portion is slightly curved and deformed, the appearance will not be significantly impaired.

FIG. 4 is a diagram showing the structure of the present invention in comparison with the conventional structure shown in FIG. The surface portions 20.21 are adapted to be easily deformed.

Therefore, the state after molding is as shown in FIG. 4, and although both rising surface portions 20 and 21 are deformed, deformation of the flat top surface portion 23 is prevented.

If the rising surface portions 20° 21 of the trapezoid shaped portion are made easy to deform in this way, each rising surface portion 20° 21 absorbs the deformation, so compared to the case where only one rising surface portion is made easy to deform. There is an advantage that the amount of deformation of each rising surface portion 20.21 is reduced.

FIG. 5 shows an example of a structure in which the height of the trapezoidal portion is small, that is, the height difference between the base surface portion 18' and the top surface portion 16' is small and the dimension of the rising surface portion 17' is short.

In the figure, 13 and 14 are the upper and lower liners, respectively, and 15 is the center core, which is the same as in the previous embodiment.

In this case as well, by crushing the center core 15b of the rising surface portion 17', the rigidity of the rising surface portion 17' is reduced and the core portion 17' is made easier to deform. However, it is possible to prevent
When the dimensions of the rising surface portion 17' are short as in this example, a sufficient effect cannot be obtained unless the degree of crushing of the rising surface portion 17' is increased.

In such a case, only a portion of the rising surface portion may be crushed as shown in 24 to facilitate deformation of the core portion, thereby preventing deformation of the top surface portion.

As is clear from the above description, the distortion prevention structure of the molded corrugated board of the present invention is achieved by crushing and deforming at least a part of the center of the rising surface of the trapezoidal or step-shaped molded part of the molded corrugated board more than other parts. Although it has a simple structure that can be easily molded, the deformation that conventionally occurred on the top surface, etc. occurs on the rising surface, and this prevents deformation on the top surface, so the external shape is particularly problematic. It is effective for molded corrugated cardboard.

[Brief explanation of drawings]

Figure 1 is a perspective view of the formed corrugated board, Figure 2 A is the I of Figure 1.
-N line sectional view, Figure 2B is a diagram showing the state in which the cardboard is warped upwards when the upper die is pulled up during hot press molding, Figure 3 is a partially enlarged side view of the structure of the present invention, and Figure 4 is The overall view is similar to FIG. 2A, and FIG. 5 is a partially enlarged side view of another embodiment. 11...Molded cardboard, 12...Trapezoid shaped part, 13.14...Liner, 1 16'...Top surface part, 17, 1 18. 18'... Base surface section, upward surface section. 5... Center core, 16. . 7'...Rising surface part, 20.21...Both standing

Claims (1)

[Claims] 1. In a molded corrugated board in which a trapezoidal or step-shaped molded part is partially formed by heat pressing, etc., at least a part of the center of the rising surface of the trapezoidal or stepped molded part is crushed more than other parts. Distortion prevention structure of molded corrugated cardboard.