Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Starting material is nonhollow planar finite length preform...
Reexamination Certificate
1999-12-23
2002-06-11
Tentoni, Leo B. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Starting material is nonhollow planar finite length preform...
C264S154000, C264S163000, C264S322000
Reexamination Certificate
active
06403015
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process and an apparatus for molding a 3-D (three-dimensional) molded product from a sheet. More specifically, it relates to a technology for controlling the thickness of the 3-D molded product.
2. Description of Related Art
A skin
100
of an instrument panel, as shown in
FIG. 20
, is molded by heating and softening a thermo-plastic resin sheet while clamping its peripheral part, by pressing the sheet into a vacuum-mold by a plug so as it to be deformed while elongated, and by adhering the sheet to a 3-D molding surface by vacuuming and suctioning it by the vacuum-mold. A crimp pattern (not shown), which is formed on the 3-D molding surface, is transferred to the surface of the instrument panel skin
100
.
Because the sheet is deformed while elongated as described above, the thickness of the skin
100
is thinned in comparison to the thickness of the original sheet. However, as shown in
FIG. 21
, problematically, the color, feel, strength, and other attributes of a convex top part
101
(the region where the sheet is molded in vacuum by being pressed into a deep concave part of the 3-D molding surface) and its side part
102
of the skin
100
differ from the other parts because the elongation percentage is very large and the skin is very thin there.
Then, in order to suppress the elongation percentage of the convex top part
101
and the side part
102
to assure a certain thickness, the following measures have been taken solely or in combination:
(1) Contrive the shape of the plug;
(2) Adjust a gap between the 3-D molding surface and the plug;
(3) Adjust the slipperiness of the sheet by pasting a tape, cloth, sandpaper and the like on the plug;
(4) Cool the sheet partially by the plug; and
(5) Partially adjust the heating temperature of the sheet.
However, the thickness of the convex top part
101
and the side part
102
has not been assured by the measures described above. Also, it has been impossible to improve the thickness to a value equal to or more than a thickness obtained by multiplying the inverse of a multiplying factor of the surface area of the mold (multiplying factor of the surface area of the 3-D molding surface to an area of a flat sheet on which the 3-D molding surface is projected) by the thickness of the original sheet.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process and an apparatus for molding a 3-D molded product, which allow the thickness of the 3-D molded product formed from a sheet or the thickness of a convex top and side parts to be assured.
The process of the present invention involves molding a 3-D molded product from a sheet. The molded product includes a product section, which turns out to be a product, and an extra product section, which is to be excised. The sheet is made of a thermoplastic polymeric material. The process comprises the steps of clamping the sheet at its peripheral edge; heating and softening the sheet; deforming the heated and softened sheet by stretching the sheet along a 3-D molding surface of a mold; and adhering the sheet to the 3-D molding surface to mold the 3-D molded product. A thickness of the product section is made up by moving the sheet material at the extra product section to the product section during the deforming step by partially releasing (loosing) a tensile stress of the extra product section.
The method for partially releasing the tensile stress of the extra product section is not specifically limited and the following modes (1) and (2) may be adopted, for example.
(1) A cutting section, such as a cut, a hole, or a cutout is created on a sheet region, which turns out to be the extra product section, before or during the deformation. As shown in
FIGS. 19A-19J
, the shape of the cutting section (
51
) is not specifically limited. The cut may be a straight line or a curve, the hole may be a circle, an oval, or an oblong shape and the cutout may be V-shaped or U-shaped, as shown in
FIGS. 19A-19J
, in order from the top. Circular holes may be created at the edges of the cut, as shown in FIG.
19
I. Or the cutting section may be intermittent, as shown in FIG.
19
J. The cutting section from which a sharp edge is removed like the circular, elliptical and U-shape cutting sections and ones in which circular holes are created at the ends of the cut prevent the sheet from breaking unnecessarily at the edge. The cutting section may be created manually or by a cutting mechanism.
(2) A peripheral edge of a sheet region, which turns out to be the extra product section, has not been clamped before or during the deformation.
Although the mold is not specifically limited, a vacuum-mold and a compressed air-mold may be adopted, for example. When a vacuum-mold is used, it is preferable that the sheet is suctioned from a part of the 3-D molding surface corresponding to the product section so as the sheet to be adhered to the part, and that the sheet is not suctioned from a part of the 3-D molding surface corresponding to a sheet missing part, which is created after moving the sheet material at the extra product section during the adhering step.
Preferably, the sheet is deformed while being elongated along the 3-D molding surface by being pressed into the mold by a plug. Preferably, the plug is formed such that a gap between the plug and the 3-D molding surface after the sheet is pressed ranges from a value approximately equal to a thickness of the sheet after being pressed, which is thinner than that before being pressed, to a value 3 mm greater than a thickness of the sheet before being pressed. However, it is possible for the gap to be larger than that range at exceptional regions, such as the vertical region and the undercut region.
Another aspect of the present invention is an apparatus for molding a 3-D molded product from a sheet. The molded product includes a product section, which turns out to be a product, and an extra product section, which is to be excised. The sheet is made of a thermoplastic polymeric material. The apparatus comprises a clamp mechanism for clamping the sheet at its peripheral edge; a mold having a concave 3-D molding surface; and a plug for deforming the sheet while elongating the sheet along the 3-D molding surface by pressing the sheet into the mold. The mold or the plug is provided with a cutting mechanism for creating a cutting section at a sheet region, which turns out to be the extra product section, before or during the deformation.
Still another aspect of the present invention is an apparatus for molding a 3-D molded product from a sheet. The molded product includes a product section, which turns out to be a product, and an extra product section, which is to be excised. The sheet is made of a thermoplastic polymeric material. The apparatus comprises a clamp mechanism for clamping the sheet at its peripheral edge; a mold having a concave 3-D molding surface; and a plug for deforming the sheet while elongating the sheet along the 3-D molding surface by pressing the sheet into the mold. The clamp mechanism is arranged so that a peripheral edge of a sheet region, which turns out to be said extra product section, has not been clamped before or during the deformation.
When the mold is a vacuum-mold in the above respective apparatus, it is preferable that the vacuum suction pores are created at a part of the 3-D molding surface corresponding to the product section and that no vacuum suction pores are created at a part of the 3-D molding surface corresponding to a sheet missing part, which is created after moving the sheet material at the extra product section.
In the same manner, when the mold is a vacuum-mold, it is preferable that the mold or the plug is provided with a sealing member for preventing a vacuum leak from a sheet missing part, which is created after moving the sheet material at the extra product section. The sealing member may be a plate-like, bar-like, or ring-like sealing member made of heat resistant rubber foam or resin foam.
The vacuum-mold is
KTX Co., Ltd.
Pillsbury & Winthrop LLP
Tentoni Leo B.
LandOfFree
Process for molding three-dimensional molded product from a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for molding three-dimensional molded product from a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for molding three-dimensional molded product from a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2932380