Apparatus for expanding tubular material
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an externally held, adjustable spreader for tubular materials present in a flat state. The spreader includes at least two spreading and guiding units which are laterally juxtaposed in the interior of the tubular material. Each unit is provided with at least one endless transporting belt which extends over part of its circumference along the outer guide face of the associated guide unit and is in releasable engagement with feed rollers disposed on the exterior of the tubular material to pass through. 
     2. Description of the Background 
     German Pat. No. 2,939,085 and U.S. Pat. Nos. 2,553,074 and 3,479,706 disclose spreaders disposed in the interior of a tubular material in the form of a flat frame that can be adjusted in width by means of a telescoping tube and in which the outer ends of the telescoping tubes are connected with the frame by way of head members. 
     However, these kwown spreaders all have the serious drawback that they are adjustable in width by way of the telescoping tubes only within relatively narrow limits. Adjustment of the spreader while tubular material is passing through, for example successive, connected tubular materials of different widths, is not possible. If the width of the tubular material passing through changes, its feed must be interrupted, the materials having the different widths must be separated from one another and the width of the spreader must be adjusted accordingly or, if its adjustment range is insufficient, the speader must be exchanged. This constitutes a very undesirable and cumbersome interruption of the work process which is desired to be as continuous as possible. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a spreader which does not have the above-mentioned drawbacks of the prior art spreaders, i.e. in which the width adjustment range can be selected at will and in which the width can be adjusted externally even if tubular material is clamped in. 
     This is accomplished according to the invention in a spreader of the above-mentioned type in that each one of the guide units is held in position by means of externally engaging supporting rollers whose axes of rotation extend perpendicularly to the direction of passage of the tubular material and which are in releasable engagement with counterrollers rotatably mounted in the guide units and at least the feed and support rollers associated with the one guide unit are arranged to be jointly adjustable in the spreading direction so as to change the spreading width of the spreader. 
     In this connection, it is advisable to have each pair of one feed roller and one support roller arranged on a common axis of rotation. To properly hold the spreading and guiding units, it is additionally advisable, when seen with respect to the plane of passage of the material, to have at least two pairs of feed and support rollers arranged on the one side of each spreading and guiding unit and at east one pair of feed and support rollers on the other side in such a manner that no tilting moment is exerted on the thus supported spreading and guiding unit. 
     To laterally fix the spreading and guiding units, it is advantageous for the support rollers to be provided, along their circumferences, with a guide groove which is in form locking engagement in a direction parallel to its axis of rotation with a counterroller of the spreading and guiding unit to be supported. 
     To realize the most uniform possible conveyance of the tubular material over the spreader, it is further advisable to connect the feed and support rollers associated with one spreading and guiding unit with a common drive. 
     It is additionally of advantage for the feed and support rollers disposed on the sides of a spreading and guiding unit facing away from one another to be arranged so as to be adjustable toward and away from one another. 
     It is additionally advisable, for the purpose of upsetting, i.e., broadening and axially shortening the tubular material being transported over the spreader, to provide each one of the two spreading and guiding units with at east two endlessly rotating transporting belts which are driven at different speeds and succeed one another along the outer guide faces. 
     It has further been found to be of advantage for the transporting belts to be made of a rubber elastic material and to have a circular cross section. 
     A more complete appreciation of the invention and many of the attendant advantages thereof will be readily perceived as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1, a plan view of a first exemplary embodiment of a spreader according to the invention; 
     FIG. 2, a longitudinal sectional view along line II--II of FIG. 1 of one of the spreading and guiding units; 
     FIG. 3, a cross-sectional view along line III--III of FIG. 1 through one of the spreading and guiding units; 
     FIG. 4, a sectional view along line IV--IV of FIG. 2 of one of the two spreading and guiding units; 
     FIG. 5, a sectional view similar to FIG. 2 of a second exemplary embodiment of the spreader according to the invention; 
     FIG. 6, a schematic illustration of the arrangement of the transporting belts in a spreading and guiding unit provided with two transpoting belts that are driven at different speeds in a further exemplary embodiment of the spreader according to the invention; and 
     FIG. 7, a view in the direction of arrow A in FIG. 6. 
    
    
     As can be seen in the drawing, the first exemplary embodiment of the spreader according to the invention, shown in FIGS. 1 to 4, includes two spreading and guiding units 2 and 3, arranged laterally juxtaposed in the interior of a flat knit tube 1 to be treated, with only the contours of the tube being indicated. The spreading and guiding units are each provided with an endless transporting belt 4 extending along their exterior guide faces and being guided, by means of guide rollers 5, 6 and 7 which are disposed approximately in the center plane of the tubular material in the two units 2 and 3. 
     The two spreading and guiding units are configured so as to taper toward the side where the tube abuts so that the incoming flat tubular knit material 1 which is to be expanded in width is quite gradually expanded in width while moving onto the spreader. 
     Feed rollers 8, 9, 10 and 11 which move on both sides over the exterior of the tubular material passing through and engage at it as well as support rollers 12, 13, 14 and 15 serve to hold the spreading and guiding units 2 and 3 within the tubular material 1. 
     Feed rollers 8 to 11 are in engagement with the portion of endlessly rotating transporting belt 4 which is exposed on the exterior guide faces of spreading and guiding units 2 and 3, respectively, drive this belt according to the desired feeding velocity of the tubular material 1 which is to be stretched in width and serve simultaneously to support the associated spreading and guiding units 2 and 3, respectively. 
     As can be seen particularly in FIGS. 1 and 4, the structure is simplified in that one feed roller and one support roller are combined into a pair of rollers forming a single unit whose axis of rotation 16 extends perpendicularly to the direction of passage of the tubular material 1 to be stretched. As can be seen particularly well in FIG. 2, support rollers 12 to 15 in turn are in releasable engagement with counterrollers 17, 18, 19 and 20, respectively, which are rotatably mounted in the associated spreading and guiding units 2 and 3, respectively. 
     To change the width of the spreader, the feed and support rollers 8 to 15 associated with the right spreading and guiding unit 2 of FIG. 1 and serving to support the latter are disposed jointly in a carriage 21 which can be displaced transversely to the feed direction C in the direction of arrow B. 
     Along their circumference, support rollers 12 to 15 are each provided with a guide groove 22 which is in engagement, parallel to their axis of rotation 16 and in a form locking manner, with a respective counterroller 17, 18, 19 and 20 of the spreading and guiding units 2 or 3, respectively, to be supported. 
     In this way, counterrollers 17, 18, 19 and 20 which engage in guide grooves 22 of support rollers 12, 13, 14 and 15, respectively, and support the latter, and feed rollers 8 to 11 which absorb the tilting moment and assure the driving of transporting belt 4 assure that the spreading and guiding members 2 and 3, respectively, are fixed in position within the passing tubular material 1, namely parallel and transversely to the direction of movement of the passing tubular material 1. 
     To realize a uniform feed of the tubular material 1 to be spread, all feed and support rollers 8 to 11 and 12 to 15, respectively, are given the same exterior diameters and are connected with a common drive. 
     To be able to take the two spreading and guiding units 2 and 3 out of the mount formed by the feed and support rollers 8 to 11 and 12 to 15, feed and support rollers 8, 9 and 12, 13 disposed on one side of spreading and guiding units 2 and 3, respectively, are mounted in a common carriage 23, which is displaceable perpendicularly to the plane of the tubular material. 
     FIG. 5 shows a sectional view similar to FIG. 2 of a second exemplary embodiment of a spreader according to the invention, with here, in contrast to the above-described first embodiment, only three pairs of feed and support rollers 8, 9, 10 and 12, 13, 14, respectively, being provided which are driven by a joint drive chain 24. Parts analaogous to parts of the above-described first embodiment are given the same reference numerals so that a repeated description of these parts should not be necessary. 
     To upset the tubular material 1 transported over the spreader, each one of the two spreading and guiding units 2 and 3 may be provided, for example, with two successive endlessly rotating transporting belts 4 and 4&#39; which are driven at different speeds along the outer guide faces of the spreading and guiding units, as this is shown very schematically in FIGS. 6 and 7. In this case, the rate of rotation V 1  of the first transporting belt 4 is greater than the rate of rotation V 2  of the second, subsequent transporting belt 4&#39;. 
     At the point of transfer from transporting belt 4 to 4&#39; the belts overlap one another.