DESCRIPTION

The present invention relates to the field of lines or plants for treating or processing flexible sheet materials.

A preferred application of the present invention is handling animal leathers subjected to tanning processes.

It goes without saying that the present invention may also find application in handling any type of flexible sheet material, meaning hides, synthetic leathers, textiles, non-woven fabrics, plastic sheet materials and the like, and others.

In tannery processing, and more generally where large hides must be handled, the problem of correctly loading the pieces onto the treatment and processing lines is very felt. In fact, the loading of the individual pieces in sequence must ensure that they are positioned in an orderly manner and, above all, meet a condition of complete stretching of the hide, without upturned flaps, creases, wrinkles or irregularities in general.

Precisely because of the complexity of such passages, the steps which require positioning the leathers according to a predefined arrangement in relation to the operating units used for the treatment of the leathers, are often carried out in a mainly manual manner.

The difficulties involved in positioning the leathers are in fact intrinsic to the type of material to be processed; by their nature, the various sheets of leather have irregular dimensions and shapes and may have different thicknesses, as well as belonging to non- homogeneous types.

The manual positioning then ensures a certain manoeuvring speed and leaves the operator with the possibility of solving problems related to the variability of the supports from which the leather is taken and its orientation (for process reasons, the leathers may be stacked so that each one has its grain side in contact with the grain side of the hide underneath, which, consequently, is oriented in the opposite direction and must be correctly positioned).

It is true, however, that technology is moving towards fully automated solutions because the use of humans not only entails inevitable uncertainties in the precision and repeatability of the processing chain, but also involves a non-negligible risk of potential physical hazards or risks to the operator's health.

Equipment has currently been developed which is capable of making the handling and loading of even large and very irregularly shaped hides particularly reliable and implementing the effective positioning of flexible materials in a lying position stretched out on various types of surfaces, both fixed and movable.

Despite the effectiveness of such equipment, there is still the problem of correctly presenting the sheets of flexible material at their openings.

Going into more detail, the sheets of flexible material arrive at the work area arranged on various supports, such as air passages, trestles, hangers, pallets. For example, the sheets are stacked on top of each other on the trestles and straddle a central support; in such a configuration, each sheet defines two flaps on either side of the support, arranged inclined with respect to a plane perpendicular to the ground, in a sort of inverted U-shaped configuration. In order for the single sheet to be available to be correctly gripped by the handling equipment, it must be 'separated', i.e. , one of its flaps must be lifted and then isolated from the rest of the stack of sheets underneath in order to have at least one free edge with which the handling equipment can make contact.

The applicant notes that in the state of the art, to its knowledge such a separation operation is still carried out manually, especially starting from a situation of sheets stacked on trestles. In fact, in this specific case, the positioning of the sheets, stacked in an inverted U-shape, on inclined planes, makes the operation of separating individual sheets particularly complex.

It is therefore the applicant's aim to develop a device which solves this problem and allows the process of separating individual sheets of flexible material to be automated.

The object of the device according to the invention is therefore to operate the separation process in an automated, repeatable and industrializable manner.

Further, the device according to the invention implements the object of presenting the individual sheet to the handling equipment in the correct position for gripping, according to a correct orientation, a condition of complete stretching of the hide, without upturned flaps, creases, wrinkles or irregularities in general. The characteristics and advantages of the separating device according to the present invention will become clearer from the following description of an embodiment thereof, given by way of a non-limiting example with reference to the appended drawings wherein: figure 1 shows a processing plant of a sheet of flexible material in which a stack of a plurality of sheets of such material stacked on top of each other and arranged on a trestle, a separating device, and a work station downstream of such a separating device can be seen; figure 2 shows the separating device in the gripping step of a flap of a first sheet of such a stacked plurality of sheets; figure 3 shows the separating device in a lifting step of said flap; figure 4 shows the separating device in isolation; figure 5 is a view of a suction opening for gripping the flap; figure 6 is again a view, this time from above, of the suction opening; figure 7 shows in isolation and in exploded view the gripping means consisting of several suction openings; and figure 8 is a view of the separating device and in particular the gripping means.

With reference to said figures, consider a stack of sheets of flexible material mutually stacked on a trestle C. The trestle has a configuration with sloping sides, each of which defining a stacking plane AA inclined by an angle a with respect to a vertical plane YZ and orthogonal to a ground plane identified as XZ according to a Cartesian triad defined by the horizontal X, vertical Y, transverse Z axes

For the purposes of the present description, the first sheet of such a stack defines a flap L arranged according to the stacking plane AA.

The invention specifically relates to a separating device or flap gripping and lifting device L, comprising at least:

- means 1 for gripping the flap L arranged in line along a proper transverse axis Z' parallel to the transverse axis Z;

- means 2 for pointing the gripping means in such a position as to face the flap on the plane AA, in order to exert a gripping force thereon which is substantially perpendicular to said plane AA itself; - means 3 for lifting the flap and moving the gripping means to move the latter towards and/or away from the plane AA according to a direction BB which is perpendicular to the plane AA itself.

In detail, the means 1 for gripping the flap comprise a beam 10 which protrudingly supports a plurality of suction openings 11 each such as to apply a vacuum pressure on the flap L and consequently a relative gripping force thereof.

Preferably, but not limitedly, each of the suction openings 11 protrudes perpendicularly from the beam 10.

The beam is arranged along the axis Z' and the suction openings 11 are mounted thereon in an orderly manner. In the example illustrated in the figures, there is only one row of suction openings 11 , but there may be other embodiments in which there are several rows of openings each with a variable number of openings 11.

Speaking more specifically of each suction opening 11 , with reference to figures 5 and 6, this comprises a cylindrical tubular sleeve 110 which conveys a depression to a lower end on which a specific insert 111 is arranged defining an engagement surface with the flap. The insert is mounted to the beam with the option of spring-cushioned retraction 112, compensating for any height differences. An additional pair of traction springs 113 introduces a further advantageous feature of adaptability and grip effectiveness, ensuring compensation for differences in orientation with the plane AA.

A spacer element 114 is associated with each suction opening, which protrudes parallel to the sleeve 110.

When the spacer 114 comes into contact with the flap L, the insert is spaced out and, having suitably sized the vacuum, is able to grip and detach the sheet flap from those underneath, overcoming any electrostatic forces and overcoming the limitation presented by suction cups or other vacuum systems which tend to pick up several sheets at once in the presence of sheets in breathable materials.

In a preferred form of the invention, the suction openings all touch the flap L at the same time and apply the same vacuum pressure and thus the same lifting force. This results in a more effective gripping and moving of the flap L.

According to a further aspect of the invention, there is at least one group 12 of movable suction openings on the beam itself according to the direction Z'. In a preferred embodiment solution, such at least one movable group 12 is placed at one end of the beam 10.

Going into greater detail and with reference to figures 7 and 8, a suction opening group 12 is mounted on a support 120 slidably engaged on the beam. The support 120 is in turn connected to a piston, e.g., of the pneumatic type, which allows the support and thus the suction opening group to be moved along Z' by a desired length. The purpose of this system is to widen and stretch the flap L, preventing wrinkles from appearing during the withdrawal.

Variants of this solution can envisage, for example, and not in a restrictive sense, that the movable suction opening comprises only one suction opening and/or that the movable opening group is moved by other moving means with respect to the piston described above.

In the example described, the beam 10 mounts two movable groups 12, 12', placed in correspondence with their ends, and straddling a fixed suction opening group.

Other positioning of the at least one movable suction opening group on the beam can be envisaged, such as also in a central position, as a function of the specific pull and traction requirements of the flexible sheet material.

Further, the beam 10 is supported cantilevered along the axis Z' by an upright 100.

The upright is slidingly supported on the above-mentioned moving means 3 which comprise a linear guide 30 arranged along its own horizontal axis X' perpendicular to the transverse axis Z' of the beam 10.

In an embodiment, the sliding movement on the linear guide of the upright is controlled by a piston 31.

Further, in the embodiment shown in the figures, the linear guide 30 is connected to a base 4 in a tilting manner by means of the aforementioned guiding means 2. These comprise at least one hinge 20 defining an axis of rotation Z" parallel to the Z axis and a thrust device 21 of the linear guide, such as but not limited to a piston. In a preferred embodiment, the hinges are two in number. By exerting the thrust action between the guide and the base, the guide assumes a tilted position in relation to the ground plane XZ due to the engagement with the hinges rotating around the axis Z". The inclination of the guide implies the inclination of the entire structure consisting of beam 10 and upright 100 and thus the orientation of the suction openings. The angle p is the target working angle corresponding to the preferred position in which the suction openings face frontally and parallel to the flap lying plane AA. The gripping means therefore exert a gripping force on the flap L which is essentially perpendicular to the plane AA.

In the position corresponding to the angle p, the linear guide defines a movement direction BB, which is essentially perpendicular to the plane AA.

The adjustment in orientation of the beam 10 can occur at the start of operations, therefore as a preliminary setting adjustment, or even during the course of work.

Possibly other embodiments of the guide means can be envisaged in addition to the one just described. For example, there may be solutions in which the upright is fixed and it is the beam which is rotatably anchored thereto around its own axis Z'.

Turning now to the operational description of the device, with the help of figures 1 to 3, the flap L of a first sheet of a stack of sheets stacked on a trestle is presented in plane AA. In order to be gripped by a sheet material handling apparatus placed downstream of the separating device, such a flap L must be gripped and lifted; this handling apparatus is not shown in the figures and can be of several known types.

The guide means are driven to arrange the beam 10 supporting the suction openings in the correct position with respect to the plane AA. At this point, the beam is moved along the axis BB through the moving means, approaching the flap L. When the openings 11 come into contact with or near the flap L, it is sucked and then gripped. If necessary, by driving at least one moving group 12, the flap can be stretched such as to meet specific processing requirements. Once the flap L has been gripped, the moving means move the beam away along the direction BB; this movement results in the lifting of the flap L and thus its detachment from the sheet underneath. The flap thus raised is therefore available to be gripped by the handling equipment downstream of the separating device.

A further object of the present invention is a plant for handling sheets of flexible material, such as in particular natural or synthetic leather, comprising at least the following elements: - a trestle C for stacking a plurality of such sheets of flexible material having a configuration with sloping sides, each of which defining a stacking plane AA inclined by an angle a with respect to a vertical plane YZ orthogonal to a ground plane identified as XZ according to a Cartesian triad defined by the horizontal X, vertical Y, transverse Z axes;

- a first sheet of such a stack defining a flap L arranged according to said stacking plane AA;

- handling equipment arranged downstream of said trestle C and equipped to come into contact with the raised flap L and then move such a first sheet towards a work station 5;

- such a work station 5 being located downstream of such a handling apparatus; and

- a separating device operatively placed between the trestle C and the handling apparatus such as that described above, adapted to grip the flap L and then lift it.

The separating device according to the invention achieves several advantages. In particular, it allows the automatic gripping and lifting of the flap of the first sheet of a stack stacked on a trestle, thus achieving the goal of overcoming the use of operators and thus manual intervention.

A plant which installs such a device is found to meet the requirements of speed and precision in the transport, transfer and processing of the sheet material.

In particular, the use of such a separating device in leather processing lines in the tanning industry solves the problems of the state of the art outlined above; in fact, it is particularly effective in the separation of natural or synthetic leather arranged on trestles, because it avoids human intervention and also obtains a rapid, precise and repeatable gripping of the leather sheet directly on the inclined leather arrangement plane. This facilitates the subsequent handling of the leather and its correct positioning throughout the processing process, with a clear increase in the overall quality of the process itself and at the same time a significant reduction in time.

The present invention has been described hereto with reference to preferred embodiments thereof. It is intended that other embodiments may exist which relate to the same inventive core, all falling within the scope of protection of the claims indicated below.