Method and apparatus for measuring the diameter of a rod-shaped article

Abstract

An apparatus and a method for measuring the diameter of at least one rod-shaped article. A beam splitter is arranged to split a beam coming from the radiation source into several component beams and to conduct the beams from different directions onto the rod-shaped article. A detection device includes a plurality of detectors each arranged to generate a signal indicating a shading of a respective one of the component beams caused by the rod-shaped article. The rod-shaped article is positioned in or guided through the beam paths between the radiation source and the detection device and the diameter of the rod-shaped article is determined from the signals generated in the detection device.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims the priority of German Application No. 10 2004 049 879.2-54, filed on Oct. 13, 2004, the subject matter of which is incorporated herein by reference. The content of each U.S. and foreign patent and patent application mentioned below is additionally incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] The invention relates to an apparatus for measuring the diameter of at least one rod-shaped article, in particular of the tobacco industry, with the aid of at least one preferably optical measuring arrangement, comprising a radiation source for generating a beam designed to irradiate the rod-shaped article, and a detection device for generating signals to indicate the shading of the beam caused by the rod-shaped article, wherein the rod-shaped article can be positioned in or can be guided through the beam path between the radiation source and the detection device and wherein the diameter of the rod-sha...

AI Technical Summary

Benefits of technology

[0008] It is an object of the present invention to provide a method and an apparatus of the aforementioned type which permits extremely accurate diameter measurements of rod-shaped articles, without having to subject the measuring arrangement and the rod-shaped articles to a rotating movement and which is therefore particularly suitable for diameter measurements on continuous rods.

[0012] An advantages achieved with the invention is that the diameter of the rod-shaped article can be determined with extreme accuracy, in particular for rod-shaped articles that are not round while. Another advantage is that a rotational movement of the measuring arrangement or a rotation of the rod-shaped article around its longitudinal axis is not required and the measurement according to the invention therefore does not require rotating components. The invention is therefore especially suitable for use in cases where a rotational movement in particular is not required or even desired for the processing, and thus the invention is suitable, in particular, for continuous rods.

[0013] As a result of the latter, the rod-shaped article can remain immovable during the measurement. Alternatively, it is also conceivable and especially advantageous for the operation if the rod-shaped article is moved continuously or discontinuously in a longitudinal axial direction through the measuring arrangement, wherein during one stage of the production of the rod-shaped articles, a continuous rod can be present, which can be transported in the longitudinal axial direction through the measuring arrangement, either as a single continuous rod section or as already divided continuous rod sections.

[0014] Owing to the fact that the invention permits a nearly infinite number of diameter measurements at one and the same location of a rod-shaped article, it is also possible to detect the cross-sectional shape and the ‘out of roundness,’ as well as the minimum and maximum diameter of the rod-shaped article. The latter is particularly important for determining whether the diameter is still within permissible limits. The invention furthermore can be used particularly advantageously for measuring cigarettes and filter plugs having an elliptical cross section, so that matching filter plugs and cigarette rods can be detected.

[0018] It a further exemplary embodiment, there is provided a beam-recombination device, which recombines the component beams after they pass the rod-shaped article, so that they again form a single beam in which the component beams are essentially arranged parallel to each other. The detectors in this case are substantially arranged side-by-side in a row. A particularly simple embodiment of the detection device is possible with this design since it is structurally very easy to combine the side-by-side arranged detectors. The beam-recombination device is preferably also provided with mirrors and / or at least one prism, comprising at least one mirror surface, such that it is particularly easy to redirect the component beams to the same direction.

[0019] A device for the substantially parallel alignment of the beam coming from the radiation source may be provided between the radiation source and the beam splitter. A device of this type is particularly useful if the radiation source generates a diverging beam, as is generally the case. Using such a device can also simplify the splitting of the beam into component beams since only the individual parallel sections of the main beam must be separated out to form component beams, owing to the parallel alignment. A device of this type is preferably provided with a collimator lens. A cylindrical lens can furthermore be installed downstream of the device and can be used advantageously for generating component beams.

Problems solved by technology

The difficulty with obtaining precise measurements of the diameter is that the rod-shaped articles are frequently “out of round,” meaning their cross sections perpendicular to the longitudinal axes deviate more or less from a circular shape.

However, measuring the diameter by only two cross-sectional axes is not precise enough in many cases.

To be sure, the measuring accuracy can be increased with this known arrangement, but the known arrangement in particular is not suitable for measuring the diameter of a continuous rod which does not rotate around its longitudinal axis.

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