WO2002074998A1

WO2002074998A1 - Method and device for spreading hides in a drying line

Info

Publication number: WO2002074998A1
Application number: PCT/EP2002/000252
Authority: WO
Inventors: Franco Sartori
Original assignee: Rizzi 1875 S.P.A.
Priority date: 2001-03-16
Filing date: 2002-01-14
Publication date: 2002-09-26
Also published as: ITPD20010063A1

Abstract

A machine for spreading out hides in a drying line according to the invention is composed of a moving belt on which a hide (12) is spread and which is passed below a stretching and spreading roller (13) with blades. The roller (13) is kept pushed against the hide (12) by means of at least one compressed-air piston (15) that allows continuous adaptation of the load with the reference to the local thickness, width and texture of the hide (12) and allow a programmed variation of the load according to the processed area.

Description

METHOD AND DEVICE FOR SPREADING HIDES IN A DRYING LINE

Technical Field

The present invention relates to a machine for spreading hides in a drying line and to the method according to which the work loads are prepared. Background Art

Field of use is the field of tanneries in which various types of hides, even very different from each other, are processed.

In a processing step, the hide that is very wet as it leaves a preceding processing step must be spread out and stretched as uniformly as possible without producing creases and/or local overlaps, in order to be then processed by a drying machine, where it is pressed by a plurality of rollers in order to expel as much as possible the water and other liquids that it has retained. This machine operates at very high pressures, and therefore if there are creases on the hide, not only such creases are retained but they are indeed pressed, forming defects that cannot be easily eliminated later.

In known spreading machines, the wet hide, roughly laid out on a conveyor belt, is passed together with the belt between a supporting roller made of rigid material, arranged below the belt, and a combined stretching and spreading roller with helical blades, which slides on the surface of the hide with a retrograde motion with respect to the advancement motion of the belt and therefore of the hide.

The surface sliding of the belt causes the hide to be spread out and stretched due to the helical arrangement of the blades.

A critical factor is involved in this operation and is due to the different thickness and texture of the hide in its various regions and to its different width in the regions that are gradually processed.

The spreading roller with helical blades is usually supported by a movable frame, which can be positioned by acting on handwheels that arrange it in a position that is preset but fixed with respect to the belt on which the hide rests.

Adjustment by means of handwheels is performed at the beginning of the process by taking into account the average thickness of the hide to be processed.

It is evident that in these known machines it is not possible to take properly into account the local thickness of the hide or its width or texture.

Clearly, if a small distance is maintained from the supporting belt, which is soft or resilient on its supporting devices, the specific force that acts on the hide is a function of the hide that lies below the blades of the spreading roller.

An excessive specific load can be very damaging and can lead to rupture of the hide.

Disclosure of the Invention The aim of the present invention is to provide a machine for spreading hides that allows to act in different manners depending on the type of hide to be processed.

Within this aim, an object is to provide a machine that allows to work with different loads on the stretching roller according to the processed area. Another object is to provide a programmable machine that is capable of varying the loads on the stretching roller during hide processing.

Another object is to provide a machine that has a simple structure and is simple to use.

This aim and these and other objects which will become better apparent hereinafter are achieved by a machine for spreading out and stretching hides on a drying line, comprising a roller with helical blades that acts on a hide supported by a moving belt that rests at the roller with helical blades on a supporting roller, characterized in that said roller with helical blades is controlled in terms of its pressure on the hide by means of double-acting pneumatic pistons and in that the pressure of the pistons can be adjusted according to the local thickness of the hide, according to its width with respect to the region that lies below the spreading roller, and in that the belt is made of compact plastics, while the supporting roller is soft. Brief description of the Drawings Further characteristics and advantages of the machine according to the invention will become better apparent from the description of a preferred non-exclusive embodiment thereof, illustrated only by way of non- limitative example in the accompanying drawings, wherein:

Figure 1 is a schematic plan view of the machine, illustrating a hide divided into processing areas;

Figure 2 is a schematic sectional view of the machine, taken along a central plane and illustrating in particular the thickness of the hide. Ways of carrying out the Invention

With reference to the figures, the machine, shown schematically in its essential parts, is composed of a conveyor belt 11 on which a hide 12 to be spread out is arranged.

The conveyor belt 11 is made of incompressible plastics, such as for example compact PVC.

The conveyor belt 11 and the hide 12 pass between a stretching roller with helical blades 13, which acts on the hide 12, and a soft supporting roller 14 arranged below the conveyor belt 11.

The stretching roller 13 turns in a retrograde direction with respect to the advancement direction of the belt 11 and of the hide 12, and the helical blades, which have two helixes arranged in opposite directions with respect to the center, tend to spread out and also stretch the hide 12.

The stretching and spreading roller 13 is supported by a frame, not shown in the drawing because it is schematic, and the pressure is determined by way of at least one double-acting compressed-air pistons, one of which is designated by the reference numeral 15. The double-acting pistons, such as the one designated by the reference numeral 15, allow to control the load applied by the stretching and spreading roller 13, adding their action to the weight of the roller, where necessary, or reducing its weight when an excessive load would cause damage.

Figure 1 illustrates a complete hide 12 divided into five areas designated by the letters A, B, C, D, and E.

These five areas, as also shown in Figure 2, correspond to different thicknesses and different local consistencies of the hide 12 and to a different width of the hide being processed.

The pressure to be given to the pistons 15 is set in the machine, and the pistons act on the stretching roller 13 against the hide 12 in relation to the indicated processing areas.

Merely as an indication and by way of example with reference to a normal hide, the pressures can be indicated in the following table:

Once the machine has been preset on the hides to be processed, by means of photocells or other sensors it identifies the hide that advances under the roller and controls the pressure of the air within the pistons depending on the processing area.

By resorting to variable pressures, it is possible to obtain a pressing action of the stretching and spreading roller that takes into account the local thickness of the hide, the width of the hide in the point being processed, and the consistency of the hide.

Clearly, it is possible to process not only complete hides but also half hides by varying the pressure settings.

The intended aim and the objects are achieved with the machine thus conceived.

More particularly, by using a conveyor belt made of compact and smooth PVC, the spreading of the hide is greatly facilitated, contrary to the felt belts used up to now, which tend to contrast the movement of the hide thereon.

Adaptation of the pressure of the stretching roller is achieved in combination with the resilient supporting roller, while variation of the pressure load of the stretching roller by way of the compressed-air pistons allows to have a spreading action that is suitable for the area of the hide being processed.

The result is significant, since the hide is spread and stretched without the danger of being ruined due to an excessive load or of not being spread out due to lack of action of the roller. Another advantage is that it is not necessary to act manually on adjustment rings and/or handwheels and that it is possible to vary the load during hide processing, which is practically impossible in known machines.

The machine that can be provided according to the inventive concept can have dimensions suitable for the processes to be performed, and the materials and components may be any according to requirements.

The disclosures in Italian Patent Application No. PD2001A000063 from which this application claims priority are incorporated herein by reference.

Claims

1. A machine for spreading out hides in a drying line, comprising a roller (13) with helical blades that acts on a hide (12) supported by a moving belt (11) that rests at the roller with helical blades on a supporting roller (14), characterized in that said roller (13) with helical blades is kept pushed against the hide by means of at least one double-acting pneumatic piston (15) and in that the pressure in the pistons can be adjusted according to the local thickness of the hide, according to its width and according to its consistency in the processed area, with respect to the region that lies below the roller (13), and in that the conveyor belt (11) is made of compact plastics and the supporting roller (14) is soft.

2. The machine according to claim 1, characterized in that said roller (13) is supported by a frame on which said at least one double-acting pneumatic piston (15) acts in order to increase or reduce the load produced by the intrinsic weight of the roller and of its supporting and motorization system.

3. The machine according to claim 1, characterized in that said conveyor belt (11) is made of compact plastics.

4. The machine according to claim 1, characterized in that said conveyor belt (11) is made of compact PVC.

5. The machine according to claim 1, characterized in that supporting roller (14) has a soft surface layer.

6. The machine according to claim 1, characterized in that the air pressure in said at least one double-acting piston (15) is programmable and in that the program automatically follows the movement of the hide (12) under said roller (13).

7. A method for actuating a double-acting piston of the machine according to claim 1, characterized in that it comprises the steps of : dividing the hide into consecutive areas and presetting the pressure on said at least one pneumatic piston (15) according to the type of hide, its thickness, width and texture in each area thereof.

8. The method according to claim 1, characterized in that it is performed automatically by the machine according to the movement of the hide (12) under said roller (13).