Measuring and testing – Hardness
Patent
1998-05-01
2000-03-07
Noori, Max
Measuring and testing
Hardness
73 377, G01N 340
Patent
active
060325178
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an arrangement and a method for measuring the rigidity of flat items according to the preamble of the independent patent claims.
It is necessary for the processing of letters, postcards and similar flat items in automatic letter sorting systems to measure the rigidity and the thickness of the items, because these letter sorting systems can only properly process items having specific predetermined parameters. In principle, such measurements can be carried out mechanically by means of a lever with a feeler roller and an inductive sensor. But at high transport speeds of, e. g., greater than 2.9 m/s, undesirable vibrations occur, so that rigidity and thickness cannot be determined accurately and separately with this functional principle. Moreover, a mechanical rigidity measurement requires much space and, like all mechanical arrangements, it is subject to increased wear. The aforesaid applies, in particular, to objects with uneven thickness or rigidity.
SUMMARY OF THE INVENTION
Therefore, it is the object of the present invention to propose an arrangement and a method with which a more precise rigidity measurement can be carried out on flat items. This object is solved by the features of the independent claims. Advantageous embodiments of the invention ensue from the dependent claims as well as from the description.
Compared to a mechanical rigidity measurement, the procedure according to the invention offers the advantage of a smaller space requirement, less wear and greater accuracy. It is possible, in particular, to also measure objects of uneven thickness and rigidity accurately.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following, the invention is explained in greater detail by way of drawings. The figures show:
FIG. 1 a schematic representation of an arrangement according to the invention from on top,
FIG. 2 a section along the axis A--A of FIG. 1,
FIGS. 3-5 output signals of distance measurements for flat items of different rigidity and thickness,
FIG. 6 the influence of the belt tension for a letter which is too rigid.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 illustrates a schematic representation of an arrangement according to the invention from on top, i. e., perpendicularly to the surface of the flat items 5 and 6. Conveying belts 2 are guided over a plurality of rollers 1, thus forming a conveying path 10. The conveying belts 2 are configured as twin bands, with the items being held between them in a nonpositive manner. The conveying path has at least one curved section 11 as well as at least one straight section 12. A rigidity sensor 3 is arranged in the region of the curved section, a thickness sensor 4 is arranged in the region of the straight section. The flat items are conveyed in the conveying path 10 in the direction of the arrow. The conveying belts are configured to be elastic and adjust to the thickness of the item. In the curved section, the rigidity of a flat item 5 causes an additional deflection of the outer belts during conveyance, in particular in the vicinity of the front and rear edges if the item. In the straight section of the conveying path, only the thickness of the system conveying belts/item changes according to the thickness of the item 6.
FIG. 2 illustrates the cut A--A of FIG. 1. Two thickness sensors 4, which are arranged one on top of the other, measure the actual thickness of the system conveying belts/flat item substantially perpendicularly to the direction of conveyance of the item 6. According to the invention, a laser, infrared or ultrasound scanning sensor is provided as a thickness sensor. Such scanning sensors preferably measure the change of the distance s through interference. For high speeds and high measuring accuracy, laser scanning sensors are preferred. A laser, infrared or ultrasound scanning sensor is also used as rigidity sensor 3 which detects the change of the distance based on the rigidity of the flat items 5. Thickness sensor and rigidity sensor for determining the rigidity of the it
REFERENCES:
patent: 4360108 (1982-11-01), Logothetis
patent: 4398421 (1983-08-01), White
patent: 4850491 (1989-07-01), Schultz
patent: 5147169 (1992-09-01), Miller et al.
patent: 5182722 (1993-01-01), Hain
patent: 5637811 (1997-06-01), Simard et al.
Gehl Christel
Reisig Juergen
Kunitz Norman
Noori Max
Siemens Aktiengesellschaft
Spencer George
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