Arrangement for shaping a helical tube

Metal working – Plural diverse manufacturing apparatus including means for... – Binding or covering and cutting

Reexamination Certificate

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Details

C072S049000

Reexamination Certificate

active

06256851

ABSTRACT:

BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to an arrangement for forming a helical tube having a given length.
An arrangement is known from EP 0384625 in which in a first stamping station a flange is made on a metal strip. This metal strip is then bent into a spiral-shaped form inside a forming tool and the edges of the sides which make contact with each other are flanged together. A cutting arrangement subsequently cuts the helical tube off into predetermined lengths.
Such helical tubes are made of perforated metal sheet and are used, for instance, in filter technology to provide an inner or outer support pipe for a cylindrical filter element, for example a zig-zag shaped folded filter paper. Here it is important to note that the length of the helical tube has a very low permissible variation so that matching with the other elements and the arrangement of end plates can occur properly. It has been shown that, with the currently known arrangements, the length and the evenness of the helical tube vary greatly, on the one hand because during preparation its dimension can only be determined with difficulty and on the other hand because certain impurities from the added processing liquid caused inaccuracy.
SUMMARY OF THE INVENTION
The object of the invention is to provide an arrangement for shaping a helical tube which avoids the stated disadvantages and produces a helical tube of high precision.
The advantage of the invention is that for determining the length of the helical tube, a combination of a measuring arrangement is formed of mechanical and optoelectronic parts or of mechanical and electronic parts. It has actually been shown that optoelectronic determination, when used alone, is corrupted in its measurement result by processing liquid or metal shavings, and therefore the length of the helical tubes varies greatly. In a combination with a mechanical sensor or with a mechanical measuring arrangement, such errors are effectively eliminated since direct contact is established between the measuring arrangement and the helical tube.
It is provided in one embodiment of the invention that the measuring arrangement fastened to the machine table is to be equipped with a pivoting stop. This provides the advantage that when the helical tube is moved along further, the stop moves out of the way, however when touched, it immediately produces a corresponding signal.
Another embodiment of the invention provides a slowing of the transport speed of the metal strip or helical tube by means of a first measuring arrangement or a first measuring signal, so that the actuation of the cutting arrangement occurs at lower speeds and thereby higher precision of the arrangement results.
Another embodiment of the invention is to be seen in that the measuring arrangement is arranged on a carrying system so as to be longitudinally displaceable and an electromotive drive positions the measuring arrangement correspondingly to the helical tube length to be produced.
Advantageously, a hydraulic axial piston motor is used for transporting the metal strip and also for powering the whole arrangement which has a gear mechanism for rotational speed reduction. In addition, a brake is provided which makes possible an exact positioning of the cutting arrangement in conjunction with the position of the helical tube.
In order to give the helical tube a certain stability and guidance during cutting, the tool is extended further in the front area.
For easy exchange of the tools and pipes, the forming tool and dividing roller holder is divided lengthwise and can be folded open according to an advantageous embodiment.
These and other features of preferred embodiments of the invention are based not only on the claims but also on the specification and the drawings, where each of the individual characteristics can be realized either individually or together in the form of subcombinations in the embodiment of the invention and in other fields and can represent embodiments that are advantageous as well as patentable in themselves, for which protection is claimed here.


REFERENCES:
patent: 3630126 (1971-12-01), Ronai
patent: 4058996 (1977-11-01), Schaeffer et al.
patent: 4198165 (1980-04-01), Kirschstein
patent: 4534002 (1985-08-01), Urban
patent: 4706481 (1987-11-01), Castricum
patent: 5017184 (1991-05-01), Takahori et al.
patent: 5477717 (1995-12-01), Skrebergene et al.
patent: 6112132 (2000-08-01), Grube
patent: 3718886 (1988-12-01), None

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