Plastic article or earthenware shaping or treating: apparatus – Preform assembly means and means for bonding of plural... – With treatment means other than assembling – bonding – shaping...
Reexamination Certificate
1999-02-22
2001-04-24
Heitbrink, Tim (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Preform assembly means and means for bonding of plural...
With treatment means other than assembling, bonding, shaping...
C425S513000
Reexamination Certificate
active
06220849
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sheet-decorating injection molding machine capable of simultaneously forming a resin molding and a decorative pattern on a surface of the resin molding in a mold by injection molding. More particularly, the present invention relates to a sheet-decorating injection molding machine capable of laminating a decorative sheet printed with patterns, letters and/or the like to a surface of a resin molding formed by injection molding for decoration.
2. Description of the Related Art
Various sheet-decorating injection molding methods, which simultaneously carries out forming a resin molding by injection molding and laminating a decorative sheet to a surface of the resin molding, have been proposed. Most of those known sheet-decorating injection molding methods comprises all or some of the following steps (a) to (i). These steps are performed sequentially or some of the steps are performed simultaneously or in parallel to each other (Refer to JU-B No. 3-56344 and JP-B Nos. 50-19132 and 7-41637).
(a) A sheet feeding step of feeding a decorative sheet onto the parting surface of the female mold of a mold for injection molding;
(b) A sheet holding step of fixedly holding a decorative sheet on the parting surface of the female mold;
(c) A sheet softening step of softening the decorative sheet by heating the decorative sheet with a heating plate or the like;
(d) A sheet drawing step of drawing the decorative sheet by suction and/or pneumatic pressing so that the decorative sheet conform to a surface defining a hollow in the female mold;
(e) A mold clamping step of moving the female mold toward the male mold of the mold or moving the male mold toward the female mold (the female mold is moved toward the male mold in most cases) to close and clamp the mold;
(f) An injection molding step of injecting a fluidic resin (molten resin) through the male mold in to a cavity defined by the male and the female mold and solidifying the resin in the cavity;
(g) A mold opening step of separating the female mold and the male mold from each other to open the mold;
(h) A sheet trimming step of severing marginal portions of the decorative sheet from a portion of the decorative sheet to be attached to a molding formed by injection molding; and
(i) An ejecting step of ejecting a sheet-decorated molding (product) decorated by the decorative sheet from the female or the male mold.
The simultaneous performance of the plurality of steps signifies the performance of the plurality of steps in a single process. More specifically, the decorative sheet is fixedly held between the male and the female mold in the mold clamping process (e) to carry out the sheet holding step (b) and the mold clamping step (e) simultaneously, or the decorative sheet is drawn by the heat and pressure of the molten resin in the injection molding step (f) to carry out the sheet drawing step (d) and the injection molding step (f) simultaneously.
A laminate decorative sheet or a transfer decorative sheet is used as the decorative sheet depending on the type of the product. When a laminate decorative sheet is used, the laminate decorative sheet is incorporated entirely into a molding during injection molding to form a decorative layer on the surface of the molding. When a transfer decorative sheet is used as the decorative sheet, the base sheet of the transfer decorative sheet incorporated into the surface of a molding is peeled off to leave a transfer layer on the molding to form a decorative layer.
SUMMARY OF THE INVENTION
In the sheet-decorating injection molding method, the sheet feeding step (a) of feeding a decorative sheet onto the parting surface of the female mold of a mold for injection molding is indispensable. Efforts have been made to automate the sheet feeding step. A decorative sheet feeding method disclosed in JP-A No. 5-318523 (sheet feeding method (1) uses a decorative sheet feed device and a takeup device, and unwinds a rolled decorative web to feed a fixed length of the decorative web necessary for one injection molding cycle, i.e., a decorative sheet, at a time. A decorative sheet feeding method disclosed in JP-A No. 7-241873 (sheet feeding method (2)) uses a sheet conveying mechanism provided with sheet grippers, such as chucks, capable of gripping a leading edge part or opposite side edge parts of a decorative sheet to feed a decorative sheet.
Problem does not arise in these sheet feeding methods (1) and (2) in stably and efficiently feeding a decorative sheet onto the parting surface of the female mold if the parting surface is flat. However, a sheet-decorating injection molding machine is often required to use a female mold having a generally convex or concave parting surface according to the shape of a sheet-decorated product to be molded.
For example, if a decorative sheet held on a flat parting surface is drawn so as to conform the surface of a hollow having the shape of a deep drawing die when forming a product having a curved surface of large curvatures, such as the surface of an article formed by deep drawing, by sheet-decorating injection molding, the decorative sheet is displaced and strained greatly and the decorative sheet is liable to be creased, strained and torn. If forming conditions including the intensity of heat and the level of pressure, are reduced to avoid creasing, straining and tearing the decorative sheet, it is difficult to draw the decorative sheet so as to extend in perfectly close contact with the surface of the hollow.
A sheet-decorating injection molding machine proposed in, for example, JP-A No. 9-39025 to solve such a problem uses a female mold having a generally concave, curved parting surface corresponding to the shape of a product to be formed in order that the depth of the hollow of the female mold, i.e., depth from the parting surface, need not be very great even in molding a product having a curved surface of large curvatures.
As mentioned above, the sheet feeding methods (1) and (2) move a decorative sheet in a plane when feeding the decorative sheet onto the generally concave, curved parting surface of a female mold. Therefore, the decorative sheet cannot properly be extended so as to conform the concave, curved parting surface of the female mold, a large space is formed between the decorative sheet and the parting surface and, consequently, the following sheet holding step and the drawing step cannot properly carried out.
The sheet-decorating injection molding machine disclosed in JP-A No. 9-39025 is provided with a sheet feed means for feeding a decorative sheet onto the concave, curved parting surface of a female mold, comprising a pair of flexible, elongate sheet conveying members, such as chains, ropes or belts, provided with sheet grippers for gripping opposite side edge parts of a decorative sheet. The sheet conveying members are moved along guide grooves formed in the female mold having the concave, curved parting surface to extend the decorative sheet held by the sheet grippers along the concave, curved parting surface of the female mold.
Although this known sheet feed means is able to extend the decorative sheet along the concave, curved parting surface, the sheet conveying members cannot substantially be tensioned because the sheet conveying members have free front ends, the sheet conveying members are simply unwound to feed the decorative sheet and the same are taken up after the decorative sheet has been fed onto the concave, curved parting surface of the female mold. Accordingly, it is difficult to position the sheet conveying members and the sheet grippers of the sheet feed means, the sheet conveying members and the sheet grippers held on the sheet conveying members cannot stably be moved into and moved out of the guide grooves and, consequently, it is possible that the decorative sheet cannot smoothly be fed onto the concave, curved parting surface. Generally, a female mold (movable mold) of a mold is moved toward and away from a male mold (stationary mold) of the mold to close and
Dai Nippon Printing Co. Ltd.
Heitbrink Tim
Parkhurst & Wendel L.L.P.
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