Abstract:
An adjustable belt conveyor assembly for the feeding of box panels into box making machinery where the friction track, i.e., the distance of advancement is adjustable as a result of a longitudinally adjustable intermediate belt loop in the run of an endless conveyor belt.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to belt conveyor assemblies, and in particular to adjustable belt conveyor assemblies such as may be employed in box making machinery where adjustability is required in the conveyor displacement for adaptation to boxes of different size. 
     SUMMARY OF THE INVENTION 
     The present invention suggests an adjustable belt conveyor, especially for use in conjunction with box folding machinery, where the advancement of the box panels over a given distance into the folding station is obtained by means of a high-friction conveyor belt which engages the flat box panel against a low-friction stationary slide face, thereby advancing the box panel at the speed of belt motion as long as a portion of the box panel is confined between the belt and the slide face. 
     This length of belt run over which the belt and the slide face are contiguous, which will be referred to herein as friction track, is made adjustable by the present invention so that the end point of the friction track can be set in accordance with different sizes of box panels. This adjustability is obtained in a most simple manner by providing an intermediate belt loop as part of the endless belt conveyor, the belt loop being adjustable longitudinally so as to present belt strands of variable lengths in conjunction with the fixed belt rollers, one of these variable-length belt strands being used to provide the adjustability for the length of the friction track. 
     In the preferred embodiment the intermediate belt loop consists of a longitudinal support arm which carries a belt roller or loop roller on each end and which is horizontally adjustable in parallel to the friction track. The endless belt of the conveyor thus runs from a stationary drive wheel over the two loop rollers of the support arm and from there over a second stationary belt roller back to the drive wheel. The intermediate belt loop thus causes the belt to run in three substantially parallel strand portions, two of them running away from the drive wheel in the direction of advance, while one runs in the opposite direction. Thus, when the position of the support arm is longitudinally adjusted toward or away from the drive wheel, one of the two aforementioned belt strands is lengthened, while the other one is shortened by the same amount, without affecting the belt tension. 
     The support arm for the adjustable intermediate belt loop is preferably so arranged that it is horizontally adjustable along a rail profile by means of a pivot pin which is clampable in any adjustment position relative thereto. 
     A preferred embodiment of the invention further suggests that the contact pressure exerted by the belt strand and the slide face of the friction track against the box panel is provided by the weight of the support arm and/or by a downwardly directed force component of the belt tension on the strand between the two belt rollers of the intermediate loop, obtained as a result of a slight downward slant of that belt strand. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Further special features and advantages of the invention will become apparent from the description following below, when taken together with the accompanying drawing which illustrates, by way of example, an embodiment of the invention, represented in the various figures as follows: 
     FIG. 1 shows in an elevational view an adjustable belt conveyor embodying the invention; 
     FIG. 2 shows the conveyor assembly of FIG. 1 in a plan view, representing one of several parallel operating conveyor segments and 
     FIG. 3 shows a modified portion of the conveyor of FIG. 1. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 2 illustrate in elevation and plan view an endless belt conveyor assembly which is especially suitable for the feeding of box panels into paper folding machinery. It should be understood that FIG. 2 only shows a single endless belt, and that two or more of these belts may be arranged in parallel in order to handle large box panels. 
     In FIG. 1 the belt assembly is shown to include a drive wheel 1 which advances an endless belt 9 with the assistance of a counter roller 3 which is arranged underneath the drive wheel 1. The counter roller is rotatably supported in the forked rear end of a horizontally extending guide profile 2. The latter thus extends from underneath the drive wheel to a forward point on the machine in alignment with the vertical plane defined by the belt run. A rail profile 4 is arranged in parallel and laterally spaced from the guide profile and belt run, the rail profile 4 as well as the guide profile 2 being fixedly mounted to the machine frame (not shown). The rail profile 4 includes a horizontal slot 5 and carries at a distance from the drive wheel a roller block 6 which supports a stationary belt roller 8 by means of a trunnion 7. The roller block 6 is longitudinally adjustable for the purpose of setting the tension of the endless belt 9. As can be seen in FIG. 1, the stationary belt roller 8 is smaller and stationed higher than the drive wheel 1, in order to accommodate underneath it an intermediate belt loop, which will be described in more detail below. 
     The rail profile 4 carries on its vertical face an elongated support arm 10 which is retained against the rail profile 4 by means of a pivot pin 11. The pivot pin 11 is arranged in the rear portion of the support arm 10 and engages the slot 5 of the rail profile against which it can be fixedly retained in any longitudinal position within the slot 5 by means of a clamping lever 12. The longitudinal position of the support arm 10 is thus adjustable within the range of slot 5 by shifting the position of its pivot pin 11. On the two ends of the support arm 10 are arranged belt rollers or loop rollers 13 and 14 in alignment with the belt run so as to form an intermediate loop in the belt run which is composed of a first advancing belt strand running at the bottom of the belt run between the drive wheel and the loop roller 14, an intermediate returning belt strand running between loop roller 14 and loop roller 13, a second advancing belt strand running between the loop roller 13 and the stationary belt roller 8, and a returning belt strand running at the top of the belt run between the stationary belt roller 8 and the stationary drive wheel 1. 
     The guide profile 2 has a smooth horizontal upper slide face arranged in parallel to the bottom strand of the endless belt 9 so as to constitute a friction track for the box panel which is engaged between the low-friction slide face and the high-friction belt 9. The friction pressure is controlled by the vertical position of the front loop roller 14 on the support arm 10 and is determined, on the one hand, by the weight of the support 10 and loop roller 14 tending to push the latter downwardly in relation to the pivot pin 11, and on the other hand, by the direction of pull on the intermediate belt strand between the loop rollers 13 and 14 which, in the case illustrated in FIG. 1, is slanted so as to produce an additional downward-directed force component. It should be understood that other means for controlling the friction pressure would likewise be suitable, such as resilient biasing means, like springs etc. 
     The horizontal adjustability of the support arm 10 and its loop rollers 13 and 14 relative to the stationary rail profile 4 permits repositioning of the intermediate belt loop forwardly and backwardly in relation to the stationary belt roller 8 and drive wheel 1 without any change in the belt tension. This is made possible through the parallel arrangement of the advancing bottom strand with the likewise advancing intermediate belt strand between the rear loop roller 13 and the stationary belt roller 8. Thus, when the support arm 10 is shifted forwardly, the first advancing strand is lengthened while the second advancing strand is accordingly shortened. An adjustment of the support arm 10 away from the drive wheel 1 thus increases the effective length of the friction track. 
     The guide profile 2 further includes in its upper portion a longitudinal groove 15 inside which is positioned a stop rod 16. The latter is so arranged that it forms a part of the slide face of the guide profile in cooperation with the bottom strand of belt 9. However, the stop rod 16 extends forwardly a distance beyond the length of the guide profile 2 and includes at its forward extremity a positioning abutment (not shown) for the box panel in the folding station. This stop rod 16 is also longitudinally adjustable in relation to the stationary guide profile 2 so as to accommodate various sizes of box panels. The adjustment of the stop rod 16 is accomplished by means of a rod clamp with a clamping lever 17. The rod clamp is arranged at the rear end of the stop rod 16 and cooperates with a longitudinal slot in the guide profile 2. 
     Although the friction track of the preferred embodiment as illustrated and described above consists of a simple stationary slide face cooperating with the bottom strand of the endless belt, it should be obvious that a second endless belt may be arranged to run in parallel with the conveyor belt, as shown in FIG. 3, counter belt 19 is guided over the counter roller 3 and a similar roller 18 at the front end of the guide rail 2&#39;. In this case the stop rod 1 is arranged elsewhere on the assembly. 
     It should be understood, of course, that the foregoing disclosure describes only a preferred embodiment of the invention and that it is intended to cover all changes and modifications of this example of the invention which fall within the scope of the appended claims.