Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
2000-10-26
2004-09-14
Lee, Edmund H. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S268000, C264S275000, C264S247000, C425S127000, C425S129100, C425S387100, C425S392000, C425S403100
Reexamination Certificate
active
06790400
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for molding a receptacle fitted with a covering label.
DESCRIPTION OF THE RELATED ART
The technical field of the invention is that of molding a receptacle out of plastics material.
The invention applies particularly to the method of manufacturing a plastic material package covered by a label over a portion of at least one face, in particular a portion of an outside face; more particularly, The invention relates to packages such as boxes, pots, bottles, or tubes (e.g. for receiving gases, liquids, or pastes, in particular foodstuffs such as yogurt) where the substantially one-piece structure body can have a bottom-forming wall and one or more side walls e.g. extending over a surface of revolution about an axis perpendicular to the plane of the bottom, such as a cylinder or a truncated cone; the invention applies more particularly, to such packages or receptacles that are of relatively small size, i.e. in which the largest dimension is less than one meter, e.g. of the order of 5 cm to 30 cm.
The invention applies to this type of package as obtained by molding, generally injection molding of plastics materials, in a mold that has at least two portions that move relative to each other: a female portion or “matrix” that has at least one cavity corresponding to the outside shape of the receptacle that is to be manufactured, and a male portion or “core” that has at least one projecting portion corresponding to the inside face of the receptacle that is to be manufactured.
The invention also applies to such packages where the label is secured to the plastics material body by adhesion obtained by molding over the label, i.e. by inserting the label into the mold prior to the plastics material that is to form the body of the package itself being introduced into the mold; The label is of a shape that matches the final shape of the package, and it is generally obtained from a sheet of paper or plastics material such as polypropylene in particular, which is cut out to the desired shape and covered in patterns by any conventional printing method.
In general, prior to each molding cycle, a plane label (i.e. a label that is disposed flat) is transferred to a mold, e.g. by a clamp and/or suction cup system, generally from a magazine that contains a stack of labels, and there are two main techniques for doing this;
A first technique uses a transfer tool (or mandrel) of a shape that is suitable for penetrating into the inside of the mold matrix. The initially plane label is placed around the mandrel and is simultaneously deformed so as to take up the outside shape of the mandrel; The label deformed in this way is held in contact with the outside face of the mandrel by applying electrostatic forces or by establishing suction (by sucking air) at the outside face of the transfer mandrel, i.e. beneath the label; After the transfer mandrel carrying the label has been moved from the storage magazine to the inside of the cavity of the matrix, the means for holding the label on the matrix (electrostatically or by suction) are deactivated; the label tends to return to its initial plane shape because of the relative stiffness of the material(s) from which it is made, so it separates from the transfer mandrel and comes into close contact with at least a portion of the faces of the cavity-forming female portion of the mold; After the mandrel has been removed from the cavity and the core (or punch) has penetrated therein, plastics material is introduced into the space between the core and the matrix and also into the space between the core and the label, thus causing the label to be pressed against the walls of the matrix under drive from the forces exerted thereon by the injected plastics material.
Patent FR 2 627 744 (Gizeh Sarl) describes another technique for automatically manufacturing a receptacle with a covering label in which labels are transferred from the magazine to the mold by two rotary clamps which roll the label up into the form of a cornet, the label as rolled up in this way being taken hold of by a transfer clamp which inserts the label in the mold matrix. The rotary clamps roll the label up into a cornet by causing the free ends of the label to overlap, and the label rolled up into the shape of a cornet is then taken hold of where its free ends overlap by the transfer clamp which inserts the rolled-up label into the matrix.
Those known techniques have the drawback of generally requiring the matrix to be fitted with suction means for holding the label in place in the cavity until the plastics material is injected.
Another drawback of methods in which a transfer mandrel is used is the lack of accuracy with which the label is positioned on the mandrel, and the way the label deforms during and after being put into place on the transfer mandrel; This drawback is not resolved by the above-mentioned French patent; consequently, the positioning of the label in the mold cavity lacks precision, and that leads to receptacles being manufactured that are defective because the label is in the wrong position.
Another major drawback is that accurate handling and positioning of the Label by clamps or suction cups is not possible when the label is very thin, e.g. having a thickness of less than 80 microns; Labels that are that thin are fragile and difficult to handle, and they tend to deform and/or move in uncontrolled manner under the effect of their own weight or under the effect of the mechanical stresses caused by mechanical contact between the labels and the handling members (even though attempts are made to minimize those forces), or indeed under the effect of electrostatic forces; In addition, their small thickness gives rise to small stiffness and that can be insufficient to enable the label to separate spontaneously from the mandrel or other transfer means, which can prevent positioning and holding in the cavity of the matrix or which can at least make it more difficult, or indeed which can require holding forces to be applied thereto by auxiliary means such as electrostatic means or pneumatic means (operating by suction).
Unfortunately, it is advantageous in some cases, in particular for the purpose of keeping down costs, to use labels having thickness of the order of 10 microns to 40 microns.
SUMMARY OF THE INVENTION
The object of the invention is thus to propose an improved method and apparatus for automatically manufacturing packages or receptacles that include a label.
An essential object of the invention is to provide such methods and corresponding apparatuses for implementing them to make it possible to provide a package manufacturing cycle time that is as short as possible; the time required for injection (which can lie in the range of a few seconds to a few minutes depending essentially on the dimensions of the package) is penalized (i.e. lengthened) by the time required for transferring the label into the mold, which time can be greater than 5 seconds when a mandrel is used.
From this point of view in particular, the system for transferring labels from the magazine to the mold by means of members such as mandrels or clamps not only leads to mechanical structures that are complex and expensive (and which also need to be adapted to the shape of each label and thus need to be interchangeable in order to manufacture receptacles in a range of shapes or sizes), but they also increase cycle time and slow down manufacturing throughput.
For example, transfer devices which have electrostatic means for holding the label on a mandrel suffer from a drawback which is due to the use of electrical voltages for causing labels to adhere by the electrostatic effect on the receiving portions of the transfer means, thereby giving rise to electromagnetic disturbances to the operation of the apparatus, and they are also incompatible with thin films.
In addition, known transfer devices do not make it possible to position the free edges of the label so that they are accurately in register, i.e. edge to edge, or they are poor at so d
Muller Paul A.
Potier-Muller Colette
Lee Edmund H.
Potier-Muller Colette
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