WO1988010227A1

WO1988010227A1 - Stacking apparatus

Info

Publication number: WO1988010227A1
Application number: PCT/NL1988/000029
Authority: WO
Inventors: Eberhard Falch
Original assignee: Eberhard Falch
Priority date: 1987-06-17
Filing date: 1988-06-16
Publication date: 1988-12-29
Also published as: NL8701415A

Abstract

Stacking apparatus provided with an accumulating belt conveyor system for feeding groups of strips overlapping each other like roofing tiles to a stacking station. The belt conveyor system is equipped with adjusting means for adjusting the slope of at least a portion of the belt conveyor system.

Description

Stacking Apparatus

The present invention relates to a stacking apparatus comprising a stacking station provided with a vertically adjustable stacking platform and an accumulating belt conveyor system for feeding groups of strips overlapping each other like roofing tiles to the stacking station and for stacking said strips thereon. Such a stacking apparatus, for instance, may be used in conjunction with a machine for corrugated cardboard where a stream of mutually separated cardboard strips continuously produced at a high rate by a cutting arrangement in this machine is initially converted, through a decelerating belt conveyor system, into a continuous stream of slow-moving strips overlapping each other like roofing tiles and, subsequently, through an arrangement for creating interruptions in the stream of moving strips overlapping each other like roofing tiles, into groups of such strips overlapping each other like roofing tiles, which groups are finally carried to said stacking apparatus. The stacking station comprises a stacking platform which is vertically adjustable with driving means permitting the platform to be moved up and down between an upper position and a lower position, where the platform is put into the upper position prior to the commencement of stacking and, during stacking, is gradually moved down to the lower position in order to maintain a more or less constant dropping height for the strips to be stacked, all this being followed by the removal of the resulting stack and turning back of the platform to its upper position. The accumulating belt conveyor system should be designed such that no strips are delivered in the time -required to remove a stack from the platform in the lower position and to raise the platform to its upper position. In this time, strips are accumulated in the accumulating belt conveyor system. The conveyor belt, at least the last portion in the direction of travel by the upside of the last conveyor belt in the accumulating belt conveyor system, should be at such a slope, for a certain strip length and thickness in combination with a certain amount of overlap of the strips overlapping each other like roofing tiles, that such strips coming from the accumulating conveyor belt system are fed to the stacking station without excessive bending or buckling and without falling freely during their being stacked. The end of a strip delivered by the accumulating belt conveyor system should preferably touch the stack or the stacking platform near the far end of the stack or the stacking platform as the case may be. The angle δ between the strips overlapping each other like roofing tiles and the upside of the conveyor belt(s) of the accumulating belt conveyor system is defined by: δ = arc tan (R.d/1), where R is the proportion of overlap of the strips overlapping each other like roofing tiles, d is the strip thickness and 1 is the strip length. If the stacking apparatus is used in conjunction with the aforementioned machine processing corrugated cardboard, the decelerating belt conveyor system and the arrangement for creating interruptions in a stream of overlapping strips, R is determined by the ratio between the speed at which strips are fed from the corrugated-cardboard machine to the decelerating conveyor belt system and the speed of the decelerating belt conveyor system. Starting from the assumption that the slope of the conveyor belt, or at least the last portion of the upside of the last conveyor belt in the accumulating belt conveyor system has a downward gradient ε in the direction of travel, the angle of a strip with respect to the horizontal plane is δ-ε , when transported by the accumulating belt conveyor system.

To achieve that, without excessive bending or buckling of the strips, stacking takes place such that the ends of the strips delivered by the accumulating belt conveyor system touch the stack or the stacking platform near the far end of the stack or stacking platform as the case may be, it is prerequisite that δ-ε< 0 . The angle at which the strips are applied by the accumulating belt conveyor system in relation to the horizontal piane is often in the order of about -3 to -5 degrees.

A problem may emerge when the stacking apparatus is adjusted to relatively short and/or thick strips and has to be switched to the handling of relatively long and/or thin strips, or conversely, when the stacking apparatus is adjusted to relatively long and/or thin strips and has to be switched to relatively short and/or thick strips. In the latter case, it may be that, with the value of R remaining roughly the same, the angle δ becomes even so large that δ-ε>0, in other words, that the angle at which the strips are applied by the accumulating belt conveyor system in relation to the horizontal plane becomes positive, so that the strips applied to the stacking stations may bend, buckle and/or fall freely over a short distance. This disadvantage cannot be made good by changing the setting in height between the accumulating belt conveyor system and the stacking platform. Accordingly, it is an object of the invention to eliminate, or at least to reduce considerably, the aforesaid disadvantage and to make the stacking apparatus fit for strips of widely different sizes. In accordance with the present invention a stacking apparatus as described in the opening lines is provided, which apparatus is characterised in that the accumulating belt conveyor system is equipped with adjusting means for adjusting the slope of at least the last portion of the last conveyor belt in the belt conveyor system travelling to the stacking station. In other words, the angle ε is adjustable such that δ-ε< 0 remains valid or is preferably in the order of about -3 to -5 degrees for strips of widely different sizes. Although, for instance, in the event that the accumulating belt conveyor system includes at least two conveyor belts, the last one at the front end in the direction of travel and the second last one at the rear end in the direction of travel may be moved vertically such that the complete upside of the last conveyor belt is at an angle ε in relation to the horizontal plane, it is preferable to push out at least the last portion of the last conveyor belt travelling to the stacking station, while maintaining the spatial position of at least the front end of this conveyor belt. Here, the adjusting means are a pressing member and a control device, the pressing member preferably being constituted by a curved plate pressing against the underside of the portion of the relevant conveyor belt travelling to the stacking station, at a certain distance from the rear end in the direction of travel. In principle, the upside of the conveyor belt is forced UP over practically its full length, with a maximum in the position where pressure is applied and a minimum of practically zero at either end. If, however, in the accumulating belt conveyor system, the front portion of the last conveyor belt travelling to the stacking platform is supported by a curved running surface and the pressing member acts on the rear portion of this conveyor belt, only the rear portion of this conveyor belt is somewhat forced up. In a first embodiment of the invention, the pressing member is fixedly connected to an arm which is rotatably mounted on the shaft of the rearmost roller of said conveyor belt in the direction of travel, the rear end of which conveyor belt is also kept in a spatially fixed position, and the control device acts near the end of the arm where the pressing member is. Here, after said conveyor belt in the direction of motion, it is preferable to provide a pair of delivery rollers of which the thrust is adjustable such that the friction of strips sliding over each other is not impedimental to stacking, and of which the lower roller is attached to the end of the arm, whereas the upper roller is attached to the frame of the stacking apparatus. As the angle at which the strips are supplied in relation to the stacking platform is kept within a fixed range/span, preferably in the order of -3 to - 5 degrees, wherever feasible, the spatial position of the pair of delivery rollers should remain fixed as far as practicable. However, when the relevant portion of the conveyor belt is pushed up, with the rear roller of the conveyor belt remaining in a spatially fixed position, the lower delivery roller will have to be moved down to a certain extent to prevent that differences in height having negative effects develop. Hence, the lower delivery roller is attached to the end of the arm. Tne suspension of the upper roller from the frame is such that the pressure exerted between the delivery rollers is still kept practically constant. In a second embodiment of the invention, both the upper and the lower delivery roller is attached to the frame of the stacking apparatus; in this embodiment, the pressing member is fixedly connected with an arm capable of rotating about the shaft of said lower roller, whilst the rear roller of said conveyor belt in the direction of travel is attached to said arm near and before the lower roller. So, the spatial position of the pair of delivery rollers is fully maintained, whereas the rear roller of the conveyor belt is carried slightly upwards with the arm, when the relevant conveyor portion is pushed up.

In an elementary embodiment, the control device has two operating positions, where in one position the pressing member does not exert any pressure on the relevant portion of the conveyor belt and where in the other position the pressing member exerts such a pressure that the relevant portion of the conveyor belt incurs a change in gradient sufficient to keep δ-ε< 0 , preferably in the order of -3 to -5 degrees, for the values of δ occurring most frequently.

A value of δ-ε that is more accurately adjustable may be obtained in an embodiment in which the control device is a hydraulic, pneumatic or electric setting mechanism operated through a microprocessor which continuously keeps track of the length and thickness of the strips being stacked as well as the amount of overlap of the strips when fed to the stacking station and, in case of any change in these values, calculates the angle to which the relevant portion of the conveyor belt is to be set.

An example of a practical embodiment of the present invention will be further described with reference to the accompanying drawing figures, where: Fig. 1 shows the relevant portion of the stacking apparatus according to the invention, where strips are supplied at a small amount of overlap and are stacked correctly without the adjusting means being activated; Fig. 2 depicts the relevant portion of the stacking apparatus according to the invention, where strips are supplied at a such an amount of overlap that correct stacking fails unless the adjusting means are activated; and Fig. 3 shows the relevant portion of the stacking apparatus according to the invention, where strips are supplied at the same amount of overlap as in Fig. 2, but where correct stacking is achieved by activating the adjusting means.

In all figures, like reference numbers are used for like parts.

The invention is by no means limited to the embodiment of the example described with reference to the drawings; this embodiment only serves the purpose of illustrating the invention.

Figs. 1, 2 and 3 show in a schematic representation only the portion of an embodiment of the stacking apparatus that is relevant to the invention. The stacking apparatus comprises a stacking platform and an accumulating belt conveyor system. The stacking station has a stacking platform 1 provided with driving means (not shown) capable of moving the platform up and down between a lower position and an upper position. Prior to the commencement of stacking, stacking platform 1 is put in the upper position, whereas, together with a stack 2 being built up on it. platform 1 is gradually moved down to the lower position as stacking takes place, with the drop height of the strips to be stacked being kept more or less constant. The upper position is adjusted to the spatial position of the accumulating belt conveyor system, whereas the lower position is determined by the stacking height. In the ultimate, when a certain defined stack has been obtained, stacking platform 1 is in the lower position and the stack may be laterally taken away. Going down at a small slope, preferably at a gradient in the order of -3 to -5 degrees, the strips being stacked should come into contact with stack 2 or stacking platform 1, and that near the far end of the stack or stacking platform as the case may be (position. A in Figs. 1 and 3), be pushed subsequently further to a stopping plate 3 and finally come fully to rest on the stack or stacking platform. The accumulating belt conveyor system in this embodiment comprises a single conveyor belt 4 running over rollers, one of which is driven by a motor: the figures show only a roller 5 which is in the position which is the rearmost in the direction of travel. The rollers are rotatably mounted in a frame 6 of which the side plate in the field of view is shown. The portion of conveyor belt 4 travelling to the stacking station is at an angle of depression ε in relation to stacking platform 1. Conveyor belt 4 carries groups of strips overlapping each other like roofing tiles to the stacking station at an angle δ in relation to the upside of conveyor belt 4, so that the strips are carried to the stacking station at an angle δ-ε in relation to the stacking platform. In the situation depicted in Fig. 1, the angle δ is such small that δ-ε has the negative value required for correct stacking. In the situation depicted in Fig. 2, the amount of strip overlap, and accordingly, angle δ, is such large that the angle becomes δ- ε>0, with the value of ε remaining the same, so that no proper stacking takes place. To enable this still to be achieved, the angle ε should also be made larger. For this purpose, the accumulating belt conveyor system is provided with an arm 7 which is rotatable about the shaft of roller 5 and which has a pressing member 8 in the shape of a curved plate located at the end as well as a control device 9, mounted on frame 6, acting near the end of arm 7 where the pressing member 8 is. Control device 9 comprises a hydraulic setting mechanism 10 which is operated through a microprocessor 11. Microprocessor 11 continuously keeps track of the length 1, the thickness d and the amount of overlap R of the strips being fed to the stacking station and, upon any change in these values, it calculates the angle δ according to the relation δ = arctan (R.d/1) and then derives the value of ε from the obtained value of δ, whilst δ - ε assumes the desired value. The stacking apparatus depicted in the figures finds application in conjunction with a corrugated-cardboard machine, a decelerating belt conveyor system and an arrangement to create interruptions in a stream of strips overlapping each other. The amount of overlap R is determined by the ratio between the speed Vt at which the strips are supplied from the corrugated- cardboard machine to the decelerating belt conveyor system and the speed Vo of the decelerating belt conveyor system. The values of Vt and Vo are continuously input to microprocesor 11 by the corrugated-cardboard machine and the decelerating belt conveyor system respectively. The strip parameters 1 and d may be input manually into microprocessor 11. On account of the value of ε thus calculated, the microprocessor produces a signal through which the setting mechanism 10 is adjusted. In Fig. 3, the amount of strip overlap indicated is the same as that in Fig. 2. However, the hydraulic setting mechanism is now activated such that arm 7 turned upwards, causing that curved plate 8 presses against the underside of the portion of the conveyor belt 4 travelling to the stacking station, and that such that the last portion moves down at a larger value of ε.

The accumulating belt conveyor system is also provided with a pair of delivery rollers 12; 13. This pair of rollers brings about a thrust which is adjustable such that the friction met with by the strips during their sliding from position A to stopping plate 3 is overcome. The lower roller 12 is rotatably mounted on the end of arm 7, whereas the upper roller 13 is rotatably mounted on frame 6 through an auxiliary member 14 and a hinged arm 15 permitting the setting of the correct pressure to be exerted on the strips for feeding through. In addition, one of the rollers, roller 12 for instance, or both rollers 12,13 should be driven at preferably the same speed as that of the roller (s), e.g. roller 5, of the conveyor belt.

Claims

1. A stacking apparatus comprising a stacking station provided with a vertically adjustable stacking platform and an accumulating belt conveyor system for feeding groups of strips overlapping each other like roofing tiles to the stacking station and for stacking said strips thereon, characterised in that the accumulating belt conveyor system is provided with adjusting means for adjusting the gradient of at least the last portion of the last conveyor belt of the accumulating belt conveyor system.

2. A stacking apparatus as claimed in Claim 1, characterised in that the adjusting means are a pressing member together with a control device for pushing out at least the last portion of the last conveyor belt of the belt conveyor system to the stacking station, while maintaining the spatial position of at least the front end of this conveyor belt.

3. A stacking apparatus as claimed in Claim 2, characterised in that the pressing member is a curved plate which presses at a certain distance from the rear end of the relevant conveyor belt against the underside of the portion of this conveyor belt travelling to the stacking station.

4. A stacking apparatus as claimed in Claim 2 or 3, characterised in that the front portion of the last conveyor belt of the accumulating belt conveyor system travelling to the stacking station is supported by a curved running surface, and that the pressing member operates on the rear portion of said conveyor belt.

5. A stacking apparatus as claimed in Claim 2,3 or 4, characterised in that the pressing member is fixedly connected with an arm rotatable round the shaft of aroller of said conveyor belt, said roller being the rear in the direction of travel, the rear end of said conveyor belt also being kept in a spatially fixed position, and that the control device acts near the end of the arm where the pressing member is.

6. A stacking apparatus as claimed in Claim 5, characterised in that, in the direction of travel after said conveyor belt there is a pair of delivery rollers of which the thrust is adjustable such that the sliding friction of strips sliding over each other during stacking is not impedimental, and of which the lower roller is attached to the end of the arm, whereas the upper roller of the pair of delivery rollers is attached to the frame of the stacking apparatus.

7. A stacking apparatus as claimed in Claim 2, 3, or 4, characterised in that, in the direction of travel, after the final conveyor belt of the accumulating belt conveyor system there is a pair of delivery rollers of which the thrust is adjustable such that the sliding friction of strips sliding over each other during stacking is not impedimental, and of which the lower roller as well as the upper roller is attached to the frame of the stacking apparatus, and that, in addition, the pressing member is fixedly connected with an arm rotatable round the shaft of said lower roller, whereas, in the direction of travel, the rear roller of said conveyor belt is attached to said arm.

8. A stacking apparatus as claimed in any one of the. Claims 2 through 7, characterised in that the control device is a setting mechanism operated through a microprocessor which continuously keeps track of the length and thickness of the strips to be stacked and the amount of overlap during the supply of strips to the stacking station, and calculates the angle to which the relevant portion of the conveyor belt is to be set upon any change in these values.