Patent Publication Number: US-6659710-B2

Title: Station for forming stacks of layers of articles

Description:
FIELD OF THE INVENTION 
     The present invention relates to a station for forming stacks of layers of articles in a machine for packaging rolled paper products. 
     DESCRIPTION OF THE PRIOR ART 
     There are machines for packaging stacks of articles, in particular substantially cylindrical articles, into relative wrappings obtained from a sheet of heat-weldable material. 
     In the following, the reference will be made paper rolls, for sake of simplicity. 
     The above-mentioned machines include: 
     a grouping station, in which layers of rolls are defined, with each layer being formed by rolls arranged one beside another in an ordered way; 
     a station, in which a stack is formed by one or two layers arranged one over the other, and 
     a wrapping station, in which the stack is wrapped with a heat-weldable material to obtain the above mentioned wrapping. 
     The present invention relates to the station, in which the stack is formed. 
     There are already known stations for forming stacks of layers of cylindrical articles. 
     In particular, each of the documents U.S. Pat. No. 3,455,085, IT 1.225.033 describes a station including: 
     a surface for supporting layers of cylindrical articles coming from the grouping station, situated upstream, with the final part of the supporting surface turned toward the wrapping station and driven into a motion so as to form a kind of pendulum, so as to define as many positions as the layers to be obtained; 
     a plurality of receiving planes, which are situated one over another and whose number corresponds to the number of layers, with each of the receiving planes having one end turned toward the grouping station and being adjacent and situated at the same level as the moving end of the above mentioned pendulum in a corresponding position of the latter; 
     first means for moving the pendulum to define one of the positions; 
     second means for moving said layers along the supporting surface, acting in time relation with said first means; 
     third means for each of said receiving planes, equipped with pushing elements, which move forward synchronously and aligned vertically above the receiving planes. 
     The stack is formed on the lower receiving plane. Since the layers are moved with the same speed, there is no reciprocal rubbing between different layers during the stack forming. 
     The above-mentioned first means are connected to the pendulum and are, therefore, also driven into oscillation. Also motor means are likewise fastened to the pendulum to impose the oscillation with respect to the hinge with the supporting surface. 
     It is to be pointed out that the inertia of the pendulum and the devices connected thereto affect the time required for the passage of the pendulum from one position to the subsequent one. 
     Moreover, during its oscillation, the pendulum carries rolls, which may detach therefrom after a given speed has been reached. 
     This reduces the production rate of the stack forming station. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to propose a station for forming a stack of layers of articles that solves the above-mentioned problems, in particular that does not have parts moving with an oscillating alternate motion, which connect the plane supporting the layers of articles arriving from the grouping station, with the working planes for receiving the layers. 
     Another object of the present invention is to propose a station, in which the articles are driven into a continuous motion, so as to increase the production rate with respect to the known stations fulfilling the same function. 
     A further object of the present invention is to propose a station for forming a stack of layers of articles which does not jeopardize the operation of the grouping station, situated upstream, nor of the wrapping station, situated downstream, and which consists of combination of devices and elements easy to manufacture and of safe functionality. 
     The above-mentioned objects are obtained by a station for forming stacks of layers of articles, situated downstream of a station for feeding the layers, said forming station including: 
     a horizontal supporting surface; 
     a first surface, situated after said horizontal support surface and distanced therefrom, so as to define a window, with the dimension of said window allowing one layer of said articles layers to pass freely therethrough; 
     first moving means for moving the layers along said support surface and first surface; 
     a stationary descending ramp, which begins from the initial part of said window and extends downwards; 
     a second horizontal surface, situated after the downstream end of said ramp and below said first working plane; 
     an additional conveyor associated to at least said window and aimed at moving, cooperating with said first moving means, odd layers from said support surface to said first surface while allowing even layers coming from said support surface to pass through the window, thus directing the even layers, due to gravity, onto said stationary descending ramp; 
     second moving means for moving each even layer to said ramp and conveying said even layer to said second surface; third means for moving each even layer onto said second surface, situated below, with said even layer moving with the same speed as the corresponding odd layer, conveyed thereover by said first moving means on said first working plane. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The characteristic features of the present invention will be pointed out in the following description of a preferred, but not unique embodiment, with reference to the enclosed drawings, in which: 
     FIG. 1A is a schematic side view of the proposed station for forming a stack of layers of articles; 
     FIG. 1B is a top view of what is shown in FIG. 1A; 
     FIG. 2 is an enlarged view of a portion of the proposed station, to highlight a characteristic functional technical aspect; 
     FIGS. 3A,  3 B show technical-functional aspects of a second embodiment of the proposed station. 
    
    
     DISCLOSURE OF THE PREFERRED EMBODIMENTS 
     With reference to the FIGS. 1A,  1 B,  2 , the letter C indicates the channels guiding the stacks of cylindrical articles, e.g. rolls of paper R. 
     The channels C are connected to a conveying line  1 , which is situated below and conveys the articles (direction H) toward a grouping station  150 . 
     In the shown example, the rolls axes are parallel to the direction H, however they can be arranged also vertically. 
     The grouping, or feeding station releases intermittently, in a way known to those skilled in the art, layers S of rolls in a downwards direction, more precisely toward the station  100 , subject of the present invention. 
     Each layer S is formed by a selected number of rolls arranged one beside another, horizontal or vertical. 
     A horizontal support surface  50  extends downwards from the grouping station up to a wrapping station (not shown). 
     First moving means  10 , connected to the horizontal support surface  50 , include e.g. first spaced out bars  6 , transversal to the direction H, which are carried by two first endless chains  7 , extending along vertical planes, arranged on both longitudinal sides of the surface  50 . 
     A window  20  is made in the supporting surface  50  and its dimension is such to allow the maximum dimension of the layer S to pass therethrough. 
     The maximum dimension of the layer S is defined by a number of rolls equal to the number of channels C. 
     Downstream of the window  20 , the support surface  50  forms a first horizontal upper surface  50 A. 
     A stationary descending ramp  25 , adjustable in relation to the rolls size, is situated under the window and extends downwards from the initial part of the window up to a second horizontal lower surface  60 , situated below the upper surface  50 A. 
     The upper surface  50 A is separated from the lower surface  60  by a section, which is not smaller than the layer height, adjustable in relation to the size. 
     The window  20  features, connected thereto, the upper run  30 A of an additional conveyor  30 , formed by a pair of endless chains  31  extending in vertical ideal planes situated beside the longitudinal sides of the window. 
     At least one part of the chains is connected to the end of flexible elements (e.g. small transversal bars or rolls) which form a flexible shutter  32 , or a moving platform  32 , whose extension in the direction K of the additional conveyor is substantially equal to the longitudinal dimension of the window. 
     In the example shown in FIGS. 1A,  2 , there are two shutters  32 . 
     It is to be pointed out that, when it is in the region of the window  20 , the shutter  32  is arranged horizontally at the same level as the support surface  50 : in this situation, the continuity of the support surface  50  is restored. 
     The speed of the additional conveyor  30 , and consequently of the shutter  32  is equal to the speed of the bars  6 , for the purpose which will be explained later on. 
     Second moving means  40  are connected to the stationary descendent ramp  25  and are formed by e.g. second spaced out transversal bars  41  carried by two second endless chains  42  extending along vertical planes situated beside the longitudinal sides of the ramp. 
     The second bars involve the initial part of the ramp, and consequently of the window, and they run parallel to the ramp up to the final part thereof, as shown in FIGS. 1A,  2 . 
     Third moving means  70  are connected to the lower surface  60  and are formed by e.g. third spaced out transversal bars  71  carried by two third endless chains  72  extending along vertical planes situated beside the longitudinal sides of the lower surface. 
     Operation of the proposed station results immediately understood from the above description. 
     Each layer S comes out of the grouping or feeding station  150  and is placed onto a belt  90  to be moved away from the station  150 : this allows a first bar  6  of the first moving means  10  to act on the rear part of the layer S to pull it on the support surface  50 . 
     Afterwards, the rolls of each layer S are compacted crosswise according to a technique known to those skilled in the art, e.g. by means  80  indicated in a general way in FIG.  1 B. 
     The reciprocal positioning of the first bars  6  of the first moving means  10  and the shutters  32  is such that, when one shutter  32  covers progressively, from one upstream side toward the downstream side, the window  20  (working position Q in FIG.  1 A), a layer S, indicated as odd layer SA in FIG. 1A, is placed on the shutter and the first moving bar  6  acts on its rear part. 
     Thus, the combined action of the shutter  32 , which moves in the direction K and of the first bar  6 , which moves in the direction H, concordant with the direction K, transfers the odd layer SA to the initial part of the upper surface  50 A. 
     The speed of the shutter is equal to the speed of the first bars  6  in order to avoid relative rubbing between the shutter  32  and the layer SA, or the disengaging of the first bar  6  from the layer SA. 
     The length of the portion of the chains  31  between two subsequent shutters  32  is such that no shutter covers the window  20  when an even layer, indicated with SB, subsequent to the previous odd layer SA, reaches the window. 
     Consequently, the even layer SB is directed, due to gravity, to the descendent ramp  25 , where a second bar  41  of the second moving means  41  acts on it (direction W, FIG.  2 ). 
     The second bar  41  transfers the even layer SB to the lower surface  60 , where a third bar  71  of the third moving means  70  acts on it. 
     The third bar  71  is situated under a first bar  6  of the first moving means  10 , aligned therewith on the same vertical plane, thus it is staggered with respect to the arrival of the bar  41  (of the second moving means  40 ). 
     Consequently, the even layer SB stops (on the lower surface  60 ) and then starts again in step relation with the odd layer SA situated above on the upper surface  50 A. 
     The first bars  6  and second bars  71 , moving with the same speed, pull the respective layers SA, SB, respectively odd and even, on the first and second surfaces  50 A,  60 . 
     Obviously, in order to form a stack of two layers, it is necessary to put the layers one over another. 
     For this purpose, the lower surface  60  can e.g. extend beyond the end of the final part of the upper surface  50 A by a section longer than the layers longitudinal extension. Consequently, the odd layer SA is put over the even layer SB without reciprocal rubbing of one layer with respect to the other, since they move with the same speed. 
     Thus, a stack P is formed of two layers SB, SA, respectively even and odd. 
     Consequently, each odd layer SA is directed, with the help of the shutter  32 , toward the upper surface  50 A; the even layer SB, preceding the odd layer SA, has been conveyed, due to the presence of the window  20 , first to the descendent ramp  25  and then to the lower surface  60 , where the even layer SB is below said odd layer SB situated on the upper surface  50 A. 
     The above-described embodiment allows formation of stacks of two layers. 
     According to the shown example, the continuity of the upper surface is restored cyclically by a shutter; it is understood that other means fulfilling the same function can be used, e.g. an endless belt moving horizontally, with one side parallel to the longitudinal extension of the window. 
     According to the second embodiment (FIGS. 3A,  3 B), the upper surface, indicated with  500 A, is moved and constitutes a shutter  132  of the additional conveyor  30  (in the shown example, there are four equidistant shutters  132 A,  132 B,  132 C,  132 D), whose upper run  30 A is long enough to extend horizontally above the lower surface  60  (from which there is a distance bigger than the layer height, adjustable in relation to the size), and to pass horizontally through the final part  100   a  of the proposed station  100 , where the two layers SA, SB, odd and even, are kept motionless and arranged one above another, e.g. placed on an elevator E. 
     FIG. 3A shows one odd layer SA situated in the region of the window  20  and lying against one shutter  132 A, the even layer SB, preceding the odd layer SA, is kept motionless in waiting position on the lower surface  60 . 
     In FIG. 3B, the shutter  132 A is situated above the even layer SB pulled on the lower surface  60  by the transversal bar  71  which is aligned vertically with the bar  6  of the first means  10 , which in turn strikes against the odd layer SA lying against the shutter  132 A (FIG.  3 B). 
     The bars  6  and  71  convey the layers SA, SB to the final part  100 A, from which they disengage at the same time (FIG.  3 B). 
     The shutter  132 A, translating in the direction K, disengages from the layers SA, SB, which cannot slide horizontally, because they are stopped by the vertical stops  91 A,  91 B. 
     The distance between the two subsequent shutters  132 A,  132 B allows to direct each of the even layers SB onto the stationary descending ramp  25  through the “dynamic” window  200  defined by the rear part of the shutter  132 A and the front part of the stationary descending ramp  25 . 
     Consequently, the layers SA, SB are conveyed on the upper surface  50 A,  500 A and the lower surface  60 , respectively, by the moving bars  6  and  71 , which are aligned on a vertical plane and are operated synchronously. 
     At the end of the upper surface, the odd layer SA is arranged over the even layer SB, situated below, without any reciprocal rubbing. 
     The support surface  50  is connected with the upper surface  50 A and with the lower surface  60  without any moving parts, oscillating alternately, but by a moving platform  32 , which bridges cyclically with the upper surface  50 A, and with the stationary descending ramp  25 . 
     This allows to simplify, with respect to the prior art, the conformation of the station for forming stacks of articles layers, and to increase the production rate. 
     The proposed station allows obtaining a stack of only one layer S, defined by a number of rolls lower or equal to the number of channels C. 
     In order to obtain a stack of one layer, it is enough that control means (FIGS. 1A,  1 B,  2 ) maintain the shutter  32  fixed in the region of the window  20 , to deactivate the second and third moving means  40 ,  70 , so that the bars  41  and  71  do not obstacle the operation of the station  100 . 
     In this situation, all the odd layers SA and even layers SB move forward orderly, in a horizontal direction, on the upper surface  50 A, which extends (see the portion  50 B indicated with broken line in FIG.  1 A), up to the elevator E, situated at the same level as the upper surface. 
     The articles to be stacked can be different from rolls of paper.