Abstract:
Bales are stacked at a fixed station within a conveyor transport path. The bales are positionally adjusted in two directions before being stacked in order to provide compact and stable stacks. The completed stacks are subsequently moved along the transport path without the necessity of any concurrent relocation of the stacking apparatus.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a method and an apparatus for stacking bales, and more particularly to stacking bales of fibre material, such as cellulose pulp. 
     A method often applied for the lifting of bales in known types of stackers such as so-called swing stackers is to clamp the bale on opposite sides by means of clamping plates. These devices involve the drawback that the unevenness, which at the pressing of the bales can arise in the bale sides, causes the bale to assume an inclined position, with the risk of tilting of the bale stack. These devices moreover, cannot be used for &#34;wet pulp&#34; with a dry content of 50 percent, because the bale is deformed by the lateral pressure. These devices are not suitable, either, for use with so-called large bales, comprising for example four stacks of sheet pulp which are lifted in unbound state for being transported to a unit load binding machine. 
     In order to overcome these drawbacks, the use of fork trucks has been proposed, but with conventional arrangements it has not been possible, subsequent to the stacking of the bales, to directly continue the transport in the previous direction of transport. The entire bale stacking apparatus, for example, has to be moved to a position where the bale stack could be delivered for further transport. 
     It is therefore an object of the present invention to render it possible to maintain the direction of transport, so that the bale stacker can be mounted in a stationary position in a transport path, thereby rendering the apparatus simpler and more reliable in operation. 
     SUMMARY OF THE INVENTION 
     The foregoing and additional objects are obtained in accordance with the principles of this invention by providing a bale stacking method and apparatus wherein bales are stacked at a station fixed within the transport path. The bales are advanced on a conveyor to a stacking position where the first bale is lifted up so that a subsequent bale can be moved beneath the lifted bale, which thereafter is positioned upon said subsequent bale. At the next step, the two stacked bales are lifted and a third bale is moved beneath the same. This procedure is repeated until the stack comprises the desired number of bales. The stack is then moved along the transport path while at the same time the next bale is moved into the stacking position. 
     The invention also provides dual adjustment means so that the bales can be adjusted in two directions, i.e. both in the direction of transport and in a lateral direction. This results in straight and stable stacks, which feature is of great importance for minimizing the size of the storage space required and for safety because of reduced tilting risk. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention will be more clearly understood upon reading of the following detailed description in conjunction with the drawing, wherein: 
     FIG. 1 shows a perspective view of a bale stacking apparatus constructed in accordance with the principles of this invention; 
     FIG. 2 depicts a side view of the apparatus of FIG. 1 with a bale moved slightly past the stacking position. 
     FIG. 3 shows the apparatus of FIG. 1 with the bale moved back to the stacking position. 
     FIG. 4 depicts an end view of the apparatus of FIG. 1, showing the operation of the lateral adjustment devices. 
     FIG. 5 shows the apparatus of FIG. 1 with the lift fork moved to its lowest position. 
     FIGS. 6-12 show the normal sequence of positions for the apparatus of FIG. 1 as it is used to align, stack and discharge bales. 
    
    
     DETAILED DESCRIPTION 
     The apparatus according to the preferred embodiment as shown in FIG. 1 comprises a feed conveyor 1, which advances the bales one by one to a stacking position. The individual bales are supplied to the feed conveyor 1 by a supply conveyor 30 as shown in FIG. 2. In order to obtain a stacking position accurately defined in the feed direction, folding stop members 2A and 2B are provided adjacent to the feed conveyor as shown in FIG. 1. A position sensing device (not shown) indicates that the bale has moved past the stop members 2A and 2B and the conveyor 1 then is reversed so that the bale is moved backward to the stop members as shown in FIGS. 2 and 3. 
     At the stacking position, shown in FIG. 4, a lateral adjustment device 3 is provided which comprises two arms 4, 5 located one on each side of the conveyor 1. The arms 4, 5 carry lateral direction plates 17, 18 and are operated by hydraulic cylinders 6, 7 so that the bale is centered laterally on the conveyor 1. The arms 4, 5 in their turn are supported by sleeves 19, 20 running on a guide means 21. 
     Above the conveyor 1, a stand 8 (shown in FIG. 1) is mounted, in which a lift fork device 9 is provided which comprises a carriage 10, which is movable on one side of the stand in a sleeve 22 by means of a hydraulic cylinder 11 along a guide means 12. On the other side of the stand the carriage 10 is guided by a roller 23 running in a guide means 24. This arrangement prevents unwanted clamping between the two guide means 12, 24 which substantially are in parallel with the conveyor 1. 
     The carriage 10 supports a lift fork 13 for the bales by means of a cross-beam 25, which can be lifted and lowered vertically by means of hydraulic cylinder 14. The movement is guided on one side of the cross-beam 25 by a sleeve 26 running along a guide means 27 and on the other side by means of a roller 28 running in a guide means 29. 
     The lift fork device 9 is located above the stacking position so that the bales move under the device 9 to the stacking position. The further transport of the bale stack is not prevented thereby. 
     The stand 8 further comprises vertical stop bars 15 located straight above the stop members 2A and 2B. Said stop bars 15 are intended to support the bale stack when it is being built up and to render it possible to pull out the lift fork 13 from the stack. Directly adjacent to the stacking position, on the same level as the feed conveyor 1 and substantially aligned therewith, a receiving conveyor 16 (shown in FIG. 12) is provided for further transport of the bale stack. 
     The apparatus operates as follows. A bale is advanced by the conveyor 1 past the stop member 2, whereafter the conveyor is stopped (see FIG. 2). The conveyor 1 is reversed and the bale is moved against the stop members 2A and 2B, which define the stacking position (see FIG. 3). The centering in lateral direction is effected by means of the lateral direction device 3 (see FIG. 4). The lift fork 13, which at the same time is in its upper position, is lowered to its rear lower position on the same level as the conveyor 1 (see FIG. 5) and is moved forward to its forward lower position beneath the bale (see FIG. 6). The lift for is lifted to its forward upper position, thereby lifting the bale (see FIG. 7). The subsequent bale now can pass beneath the lifted bale (see FIG. 8) where it is properly aligned in the direction of transport (see FIG. 9) and in the lateral direction (see FIG. 10). Thereafter the lift fork 13 is lowered so that the first bale is positioned immediately above the second one (see FIG. 11). The fork 13 is then pulled back, and the stop bars 15 retain the uppermost bale in the stacking position (see FIG. 12). Thereafter the fork 13 is lowered to its rear lower position corresponding to the position shown in FIG. 5. 
     The above-described procedure is repeated until the desired number of bales are included in the stack, whereafter the bale stack is transferred to the receiving conveyor 16 (shown in FIG. 12) for transport to subsequent working steps. At the same time, the first bale in the next stack is advanced by the conveyor 1. 
     The invention, of course, is not restricted to the embodiment described, but can be readily varied by those skilled in the art within the scope of the following claims.