The present invention relates to an apparatus for stacking hides and other flexible sheet-like products.

Apparatuses of this type can be used not only in the tanning sector but also in papermaking industries, print shops, textile and packaging industries as well as in other ones in which flexible thin sheet-like materials must be temporarily or permanently gathered and sorted to store them or send them to subsequent treatments.

A conventional stacking apparatus generally includes a movable surface for the advancement of the products in a substantially continuous manner. This surface is normally constituted by one or more single-ribbon or multiribbon conveyor belts, and is located ahead of a transfer device which is suitable to deposit and stack the products on a supporting structure. The supporting structure can be constituted by a table or truck which is fixed or movable, depending on whether the transfer device is respectively fixed or movable in the same direction.

Examples of known stacking devices are described in US patents nos. 2,263,441 and 3,405,932, in German patent no. 1,132,861, in Italian patents nos. 1,014,803 and 1,051,219, in British patent no. 2,054,527, and in European application no. 0 049 224.

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A first drawback of these conventional devices is the excessive weight of their moving parts, which, in some of the devices, perform a reciprocating motion. This severely limits the maximum speed and thus the capacity of the apparatus.

Another drawback is constituted by the poor reliability of this type of apparatus, due to frequent jammings caused by the complexity and fragile nature of the moving parts and by the difficulty in handling products that have a very low consistency.

Another drawback of this type of apparatus is its high initial cost and subsequent maintenance cost.

The aim of the present invention is to overcome the drawbacks described above by providing an apparatus for stacking hides and other flexible sheet-like products which has characteristics of high economy, reliability, productivity and flexibility.

A particular object of the present invention is to provide a stacking device the structure whereof is considerably simplified with respect to a conventional apparatus and is such as to allow a considerable reduction in both initial and running costs by virtue of its higher reliability and very limited maintenance.

Another object is to provide a stacking device having very light moving parts, so that it can be used with machines that operate at high speeds, allowing a considerable increase in

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productivity.

Another object of the invention is to provide an apparatus which is extremely flexible and is suitable to stack the products in different manners without requiring structural changes but by means of simple adjustments of its control mechanisms.

The invention achieves this aim and these objects by means of an apparatus for stacking hides and other flexible sheet-like products comprising a frame supporting a movable transport surface for the advancement of hides, or other products to be stacked, in a selected direction, and a fixed supporting structure which is located after the transport surface to support the stacked products, characterized in that it has a device adapted to grip each individual hide that leaves the movable transport surface, to roll up said hide, and to deposit said hide, in a controlled manner, on said fixed supporting structure.

Preferably, the device includes at least one roll-up roller that can turn about an axis which is substantially parallel to the movable transport surface and is located below the output edge of the movable transport surface.

The roll-up roller can have a grip means to retain each individual hide at its leading edge.

The grip means may be mechanical, pneumatic, hydraulic or electrostatic.

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The mechanical grip means can be constituted by two longitudinal halves of the roller which are substantially identical and are separated by a diametrical plane that passes through the rotation axis of the roller, the halves being spaced so as to make the leading edge of a hide pass between them.

At least one of the halves of the roll-up roller can move in a direction which is substantially at right angles to the rotation axis of the roller, and an actuation means is provided which acts on the movable half to move it toward and away from the other one, so as to retain or respectively release the edge of a hide. The movable transport surface can be formed by a plurality of single-ribbon or multiribbon belt conveyors, coupled to a second motor means so that each belt is faster than the preceding one, with a speed increase that is suitable to progressively space the hides mutually apart.

Preferably, the rotation axis of the roll-up roller is mounted on a truck that can move along a first substantially horizontal guiding means that lies between the movable transport surface and the hide supporting structure.

In turn, the first horizontal guiding means is mounted on a slider that can move along a second vertical guiding means which is anchored to the frame.

In a second aspect of the invention, a method for stacking hides and other flexible sheet-like products includes the

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following steps: continuous advancement of the hides along a movable transport surface; spacing by a preset amount that is sufficient to perform the subsequent steps on each individual hide; rolling of each individual hide by means of a roll-up roller that can rotate about a substantially horizontal axis; transfer of each hide, rolled up on the roller, from a first position which is adjacent to the output edge of the movable transport surface to a second position which lies substantially above a fixed supporting structure; and unloading of each hide onto the supporting structure.

For a better understanding of the invention, some preferred but not exclusive embodiments of a stacking apparatus according to the invention are described hereafter and are illustrated only by way of non-limitative example in the accompanying drawings, wherein:

Figure 1 is a general side view of a first embodiment of a stacking apparatus according to the invention;

Figure 2 is an enlarged-scale view of a detail of the apparatus of Figure 1, in a second embodiment;

Figure 3 is a side view of a detail of Figure 2;

Figure 4 is a perspective view, taken from a slightly elevated viewpoint, of a detail of the apparatus of Figures 1 to 3;

Figure 5 is a slightly enlarged side view of a detail of

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Figure 2 ;

Figures 6a to 6f are schematic views of some details of the apparatus according to the invention during successive operating steps;

Figures 7a to 7c are schematic views of some details of the apparatus according to the invention in a first operating condition;

Figures 8a and 8c are views of the same detail of the apparatus according to the invention in a second operating mode;

Figures 9a to 9d are views of a detail of the apparatus according to the invention in a third operating mode.

With reference to the above figures, the reference numeral 1 generally designates an apparatus, illustrated in the figures, for stacking hides or other flexible sheet-like products P arriving from a continuous conveyor belt N on a fixed supporting structure, for example on a saddle-shaped stand C or on any supporting surface.

The conveyor belt N can be the output section of a preceding treatment machine or station and has an advancement speed Vo. The apparatus generally includes a frame which is formed by posts 2 constituted by metal profiles with bases that rest on the ground or are anchored to it. The posts 2 support the output end of a conveyor belt 3, formed by a continuous wide

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ribbon or by a series of adjacent narrow ribbons closed in a loop, which has the purpose of accelerating and spacing the hides P that arrive from the conveyor belt N to allow their individual handling without mutual interference, as clarified hereinafter.

The conveyor belt 3 is stretched by respective end rollers 4 and 5. The input-end roller 4 is at a lower level and is supported by oscillating supports 6 which are pivoted to the ground, whereas the output-end roller is supported by side plates 7 which are in turn pivoted to the posts 2.

The lower roller 4 is connected to an electric motor 8 by means of a belt 9 and a pulley 10 in order to give the belt the speed V, which is expressed by the formula

V = Vo + δV

where 5V is equal to a value which is a percentage of Vo. The value of δV can be set so as to space each hide from the preceding one by a preset extent d which is required to avoid overlapping successive hides. The adjustment can be performed by varying the speed of the motor 8 according to the speed and actual position of the hides P, which is detected for example by means of an encoder 11 mounted on the roller 4 and coupled to a set of photocells 12, 12' that face the belt. The data acquired by the sensors 11, 12, 12' are sent to a microprocessor-based or PLC-type control unit 13 which is appropriately programmed, and has control peripherals for an operator. The operator in turn varies the supply voltage of

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the motor 8 by means of a feedback loop 14.

As an alternative, the transport surface 3 can be constituted by a plurality of substantially parallel conveyor belts 3', 3", 3'" formed by a continuous wide ribbon or by adjacent narrow ribbons, with respective lower tensioning rollers 4', 4", 4'" and upper tensioning rollers 5', 5", 5'". The belts 3', 3", 3'" have respective advancement speeds V, V", V" that progressively increase, and the rotation directions of the upper and lower belts 3, 3"' are mutually identical and are opposite to the direction of the intermediate belt 3' . The upper end roller 5" of the intermediate belt 3" protrudes with respect to the rollers 5' and 5"' of the upper and lower belts 3' and 3'", whereas the lower roller 4" is recessed with respect to the other two rollers 4', 4'" of the belts 3' and 3'". In this manner, each hide P that arrives from the belt N follows a sinusoidal path, first on the belt 3' which is tilted upward and directed forward, then on the belt 3" which is tilted downward and directed backward, and then on the belt 3"' which is tilted upward and directed forward.

In order to give rising speeds V, V", V"' to the various belts, the motorized rollers 4', 4", 4"' can be mechanically connected to a single motor 8 by means of a transmission belt 9 that winds around respective pulleys 10', 10", 10'" that have decreasing diameters. In this case, the values of the speed gradients δV , δV", δV ¹ " are set by the transmission ratios between the motor and the pulleys of the driving rollers.

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As an alternative, each tensioning roller 4', 4", 4"' can be connected to a respective motor, not shown in the drawings, in which case it is possible to individually vary not only the speed increase but also the value of the momentary speed in order to vary it continuously along the sinusoidal path.

It is noted that the number of belts may be any other than three but is preferably odd, so that the output edge 15 of the last belt is spaced from the input edge of the first one.

A particular feature of the invention is the fact that it has a device for gripping each individual hide that leaves the movable transport surface, rolling it up and depositing it on the fixed supporting structure. In particular, the device can be constituted by a roll-up roller 16 which has a rotation axis that is substantially parallel to the output edge 15 of the conveyor belt 3 or 3'" and is located below this belt. As more clearly shown in Figures 3 and 4, the roll-up roller 16 has a grip means which is meant to engage and retain the leading edge 17 of a hide unloaded by the belt 3. This grip means can be mechanical, pneumatic, electrostatic or magnetic and in any case is suitable to facilitate the adhesion of each hide to the outer surface of the roller.

In the case of a mechanical grip means, in a preferred solution the roll-up roller 16 is formed by two substantially identical halves 16', 16" with opposite faces 18', 18" obtained by splitting a cylindrical roller along a diametrical plane. The opposite faces 18', 18", may be covered with a soft material to avoid damaging the products

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and to increase grip. Faces 18', 18" are spaced apart in order to leave, a gap 18 between them. The gap 18 has a width sufficient to allow the leading edge 17 of a hide P to pass. The distance can be fixed or adjustable, so as to adapt to various hide thicknesses and consistencies. Proximate to the output edge 15 of the belt 3, 3'" it is possible to provide a mechanical and/or pneumatic conveyor means that has the purpose of facilitating the insertion of the end 17 of the hide P between the opposite faces 18', 18".

The roll-up roller 16 as a whole is supported by an axis 19 on which a pulley 20 is keyed. This pulley is connected to a motor 21 by means of a belt 22.

In this manner, by aligning the roll-up roller 16 so that the gap 18 between the faces 18', 18" is vertically aligned with the output edge 15 of the conveyor belt 3, 3"' it is possible to grip the edge 17 of the hide P and roll it up by rotating the roller 16 at very high speed. Startup of the motor 21 can be determined by the control unit 13 according to a signal provided by the photocell 12' or by another equivalent sensor means. The rotation rate of the roll-up roller 16 can be controlled by means of an encoder 23 mounted on its driving shaft.

As an alternative, the grip means may be activated by control, allowing one of the two halves of the roller 16 to move with respect to the other one, which is rigidly coupled to the axis 19. For example, the half 16' may be movable at right angles to the axis 19 and to the faces 18', 18", so as

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to move away from the other fixed half 16" to retain or release the edge 17 of the hide P.

A means is provided to shift the roll-up roller 16 from its first loading position, which is substantially aligned with the output edge 15 of the conveyor belt, to a second position that we may call unloading position and generally lies above the beam C.

Particularly, the shifting means may be constituted by a slider 24 which supports, the axis 19 of the roll-up roller 6 toward one end. Slider 24 can slide along lateral guides 25 which are mounted on the upper end of the posts 2. It is also possible to provide a means for moving the slider 24, constituted by an electric motor 26 which is fixed to a plate 27 that is rigidly coupled to the upper part of the posts, and drives a belt or chain 28 the ends 29, 30 of which are fixed to end portions of the slider 24. In this case, too, the motor 26 can have an encoder 26' to monitor the speed and relative position of the slider 24 in a horizontal direction. In this manner, a hide P leaving the transport surface 3 can be gripped by the roll-up roller 16 and rolled up by rotating the roller 16, for example counterclockwise, as shown in Figure 6b. When the roll-up action ends, the roller stops and the slider 24 is shifted to the right, as shown in Figures 6d and 6e, until it reaches an extreme rightward position shown schematically in Figure 6e. After this, the hide rolled up on the roller 16 begins to be unloaded by rotating the roller clockwise and by simultaneously shifting the slider 24 from right to left as shown schematically in Figure 6f.

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In order to prevent the stacked hides from slipping, and to obtain a higher unloading speed, it is possible to provide a presser member which is constituted by one or more hydraulic or pneumatic cylinders 31 which are anchored to the guiding means 25 and in which the ends of the stems 32 are suitable to support a cross-member 33 that presses slightly downward the topmost hide of the stack. The cylinders 31 can be connected to a pneumatic control unit 31' for the supply of a pressurized fluid, which is connected to the microprocessor- based control unit 13 so that it acts after the roll-up roller has started to rotate and to shift in the direction opposite to its initial one.

In order to adapt the vertical position of the roll-up roller 16 to the change in the height of the stack of hides accumulated on the beam C, the slider 24 can be generally supported by a sliding block 34 which is rigidly coupled to the plate 27 and can move along vertical guides 35 which are rigidly coupled to the posts 2. It is also possible to provide a means for moving the sliding block 34, constituted by a motor 36 which is connected by means of a belt 37 to a pulley 38 that drives a belt or chain 39, possibly balanced by counterweights, the ends of which are anchored at 39 and 40 to the sliding block 34. In this case, too, it is possible to provide a sensor means, constituted by a photocell 41 which is suitable to detect the height of the stack and to transmit a corresponding signal to the control unit 13, which supervises the stepwise rotation of the motor 36.

It is noted that the roller 16 can roll up each individual

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hide by rotating in opposite directions, so as to deposit the hides in a preset manner, according to the operating cycle selected by an operator by means of the control unit 13.

Figure 7a illustrates the fixed-point rolling of a hide on the roll-up roller 16 by rotating the roller counterclockwise. This loading step can be followed by a step in which the hide is unloaded and deposited on a surface by clockwise rotation and simultaneous shifting of the roller from right to left, as shown in Figure 7b, or by means of a clockwise rotation and left-to-right shifting of the roller 16, as shown in Figure 7c. The upper or grain side of the hide is indicated with a solid line and the lower or flesh side is indicated with a dot-and-dash line, and it is noted that in the deposition method of Figure 7b the grain faces upward, whereas in the deposition method of Figure 7c it faces downward.

Similar results can be obtained if the roll-up roller 16 rolls up the hide by rotating clockwise, as shown in Figure 8a. In this case the grain of the hide is deposited face up or face down, depending on the leftward or rightward shifting of the roller.

Finally, Figures 9a to 9c illustrate an example in which a hide is deposited and folded on a horizontal plane by reversing the direction of the shift of the roller during its rotation to unroll the hide itself.

From what has been described above it is evident that the stacking apparatus according to the invention achieves the

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intended aim and all of the objects, and particularly the light weight of the grip and roll-up assembly and its great flexibility and constructive simplicity are stressed.

The apparatus according to the invention is susceptible to numerous modifications and variations, all of which are within the scope of the inventive concept expressed in the accompanying claims. For example, instead of a single roll-up roller it is possible to provide two or more rollers that act independently and in succession so as to avoid any idle times.

All the details may furthermore be replaced with other technically equivalent ones. For example, instead of the mechanical grip means it is possible to provide a pneumatic grip means which is constituted by a roller that is connected to a suction source and is provided, on its surface, with a plurality of through micropores which are suitable to form a suction that tends to retain the hide during its initial rolling. Furthermore, the grip means can be constituted by an electrostatic device connected to a controllable energizing means.

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