Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Reexamination Certificate
1999-02-10
2001-11-27
Evans, F. L. (Department: 2877)
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
C250S559240, C356S635000, C493S012000, C493S016000
Reexamination Certificate
active
06323502
ABSTRACT:
RELATED APPLICATIONS
This application claims priority from French Patent Application France No. 98 02232, filed Feb. 19, 1998
GOVERNMENT FUNDED RESEARCH
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method, a device and use of the device for checking the accuracy of folding a parallelepiped box made from a cardboard blank
2. Brief Description of the Background Art
The blank that is used to form a cardboard box in the form of a parallelepiped comprises four adjacent panels extending between two opposite longitudinal parallel edges of the blank, the transverse sides of the panels being aligned along two parallel lines. One of the two opposite longitudinal parallel edges of the blank being formed with a gluing tab. At least some of the transverse sides of the adjacent panels are provided with flaps adapted to close the top and bottom surfaces of the box, folding lines being formed between the panels and also between the panels and the flaps. Slots having parallel edges are formed by folding the two side panels adjacent the opposite longitudinal edges of the blank on to the other two panels in order to join the opposite edges of the said blank so that the gluing tab overlaps the opposite edge.
SUMMARY OF THE INVENTION
If the folding lines between the adjacent panels of a box are not parallel, this will affect the parallelism between the adjacent edges of the slots formed by the flaps attached to the two panels adjacent the opposite two parallel edges of the cardboard blank, these edges being joined when the box is folded. The folding lines on a cardboard blank are defined by compressing the cardboard along the folding lines. Corrugated cardboard is more likely to have its faults, e.g. faulty parallelism between the folding lines, because of the corrugations which, if not exactly aligned with the compression lines, will cause the compression lines to overlap pairs of adjacent corrugations in the cardboard. In that case the fold may occur along a corrugation rather than along the compression line, resulting in a distortion in the shape of the box that is produced. This will affect the parallelism between the slots formed on the flaps adjacent the two panels of the cardboard blank that are being joined. It is therefore possible to detect folding errors in the box blank by measuring the width of the slot on each side of the folded panels and to compare the widths. This will be a measure of the defect in parallelism. The spacing between the adjacent edges of the slots will be greater between the flaps on one side of the panels than between the flaps on the opposite side of the panels. If the tolerance exceeds a certain amount fixed by the manufacturer in dependence on the type of packaging, the cardboard must be scrapped. The corrugations may also result in offsetting the position of the folding lines, which is unacceptable beyond a certain value. Measurement of the slot width also detects this error.
The object of the invention is specifically to detect the width of the two slots formed by the flaps adjacent the two end panels of the cardboard blank after the panels have been folded along the folding line, and to detect spacing beyond established norms, in order to eliminate defective cardboard boxes in accordance with an objective criterion established by the manufacturer. Unequal spacings detect nonparallel folding, while spacing that is wide or too narrow detects offset folding.
To this end the invention relates, firstly, to a method of checking the accuracy of folding a parallelepiped box as mentioned hereinabove. It also relates to a device for working the method and use of the device on a cardboard blank folding machine.
Since the folding lines between the four panels of the carton blank are parallel to the direction of travel of the blanks in the folding machine, the same applies to the slots formed between the flaps adjoining the end panels of the cardboard blank, the ends of which are joined after folding. It is therefore easy to measure the width of the slots during the motion of the folded cardboard blank in the machine. As will be seen, the measurement is preferably made employing a straight illuminated line produced by a beam of light projected at an angle to the plane of the blank, the thickness of the cardboard producing an offset between the part of the illuminated line falling in the slot and the rest of the illuminated line. This offset line is clearly displayed and can be easily measured.
In this way it is possible to check all cardboard boxes during the folding operation without wasting time by interrupting the flow of the folding machine. Consequently, the cost of the operation will be limited basically to the cost of the monitoring installation and adaptation thereof to each set of cardboard boxes. Preferably the device can be used together with a folding machine so as to automatically eliminate cardboard boxes that are not within the tolerances.
REFERENCES:
patent: 5212656 (1993-05-01), Clary
patent: 5978499 (1999-11-01), Tossel et al.
patent: 5993367 (1999-11-01), Hattori et al.
patent: 35 28 047 A1 (1987-02-01), None
patent: 0 186 619 A2 (1986-02-01), None
Evans F. L.
Friedman Allen N.
Martin S.A.
McCarter & English LLP
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