Sewing – Method of sewing – Material sensing
Patent
1998-05-27
1999-11-30
Izaguirre, Ismael
Sewing
Method of sewing
Material sensing
112153, D05B 3510
Patent
active
059923407
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is related to a method and a device for laterally aligning a lateral edge of flat material webs fed to a machining station, in which the lateral position of the lateral edge is detected transversely to a feed direction under formation of a position signal and in which the flat material webs are moved transversely to the feed direction as a function of the position signal.
2. Description of the Related Art
Methods of this type are predominantly deployed in automatic sewing machines, where it is important due to high processing speeds that the material edge is automatically guided along a predetermined path. In order to achieve this it is known (EP-B-0 383 045) to use a chain of spherical or crowned roller elements for the transverse transport, which chain can be adjusted in a plane extending approximately transversely to the sewing direction in its longitudinal direction as a function of the position signal and which lies against the material web with a plurality of roller elements having roller axes extending parallel to the aligning direction. The crowned roller elements have a rough or profiled surface structure in order to increase their frictional properties, which can lead to undesirable distortion or damage especially of fine silk or cotton materials.
SUMMARY OF THE INVENTION
Based on this it is the object of the invention to develop a method and a device of the type described above, which ensures a non-damaging yet dependable handling during the lateral alignment of the flat material webs.
The solution according to the invention is based on the idea that two elongated cylindrical friction rollers, the rotational axes of which are aligned transversely to the feed direction, are used to effect the transverse transport, which rollers are alternatingly pressed on the one hand against the flat material web and moved back-and-forth in the direction of their rotational axes between two extreme positions as a function of the position signal, thereby taking along the flat material web, while on the other hand the other roller is lifted off from the flat material web, a change of rollers being triggered whenever the extreme positions are reached. These measures have the advantage that the frictional rollers contact the flat material webs along a greater width, so that no unwanted indentation or distortion of the flat material surface can occur during the transverse transport. A further improvement in this respect is attained when the friction rollers have a surface coating consisting of elastic, preferably rubber-elastic material.
A further improvement in this respect is attained when the transverse transport is stopped during a change of rollers, which can be performed comparatively quickly with suited drive means. This is of importance especially when both friction rollers are momentarily pressed against the flat material web during a change of rollers. The transverse transport after a change of rollers can initially be continued with the substituted roller in the same direction as before the change of rollers. Advantageously, the transverse transport is slowed down by suited drive means when approaching the extreme positions, so that only small accelerating forces occur during the stopping and starting of the transverse transport. The active friction roller is pressed against the flat material web under the action of a preferably adjustable spring force.
An especially advantageous and easily realized embodiment of the invention provides that the two friction rollers are moved, by means of a motor, in opposing directions during the transverse transport and a change of rollers. Both friction rollers are expediently brought into a predetermined starting position, for example a centered position between the two extreme positions, before activation of an aligning process. Further, one of the two friction rollers is brought into contact with the flat material web.
The device for implementing the method according to the invention, which compr
REFERENCES:
patent: 3970015 (1976-07-01), Fukuyama
patent: 4616584 (1986-10-01), Vartoukian et al.
patent: 5437238 (1995-08-01), Price et al.
patent: 5497720 (1996-03-01), Kawasaki
Izaguirre Ismael
Rombold System GmbH
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