WO2001036310A1

WO2001036310A1 - A method for determining and verifying the number of sheets forming a ream of paper in a machine for selecting reams

Info

Publication number: WO2001036310A1
Application number: PCT/IB2000/001655
Authority: WO
Inventors: Andrea Cinotti; Gabriele Canini; Massimo Milani
Original assignee: Fabio Perini S.P.A.
Priority date: 1999-11-16
Filing date: 2000-11-14
Publication date: 2001-05-25
Also published as: IT1311392B1; ITBO990619A0; ITBO990619A1; EP1237807A1

Abstract

According to the method, the nominal number of sheets (No) related to the definite reams (R), which are to be formed, is introduced into a machine for selection of the reams (1). The machine (1) acquires data necessary to determine a reference weight (Po) and a selection height (Ho). A subsequent check of the weight (PR) of the selected ream (R1) allows to correct lacks or surpluses by adding or removing sheets. The check of the weight (PR) of the ream (R1) can be associated with, or otherwise, substituted by, counting the sheets of the selected ream (R1) by optic detecting marks (8) made on the side of a pile (2), from which the reams (R1) are withdrawn. The marks (8) extend on, and are separated by, a predetermined numbers of sheets, which allow the counting when they are introduced into the machine (1).

Description

A METHOD FOR DETERMINING AND VERIFYING THE NUMBER OF SHEETS FORMING A REAM OF PAPER IN A MACHINE FOR SELECTING REAMS

BACKGROUND OF THE INVENTION The present invention relates to a method for determining and verifying the number of sheets forming a ream of paper made in an automatic machine for packaging reams of paper.

DESCRIPTION OF THE PRIOR ART At present, the reams formed by a plurality of sheets of paper, m particular great reams as e g the ones formed by sheets used for sketches, prints and the like, are produced and packaged by automatic machines, which take the sheets of paper from a pile situated on a bench or pallet near the machine. The sheets of paper are withdrawn m blocks formed by a number of sheets as near as possible to the number of sheets which must form a ream.

A ream, taken by way of example referred to hereinafter, is formed by 250 sheets. The thickness corresponding to the predetermined number of sheets is determined manually or by a placing a selecting element along the vertical extension of the pile.

In case the block thickness, is determined manually , the operator separates one by one the blocks to form reams, making reference to suitable countermarks placed during the preparation of the pile of sheets between the last sheet of a pack aimed at forming a ream and the first sheet of a pack situated below and aimed at forming a subsequent ream.

The pallet is placed on an elevator, so that after each ream has been withdrawn, the pallet is automatically moved upwards. Otherwise, the selection element usually includes a blade or a wedge body, which is introduced between the sheets thus separating a block aimed at forming a ream

The blade or the wedge is placed m the ream separation area automatically or manually by an operator

The operator places manually the separation element m the region of the above mentioned countermarks, separating the blocks one after another

In case of automatic separation, as described in the US Patent no 5 244 430, the reams are separated by a suitable group The group features a blade and moves horizontally to insert the blade into the pile of sheets Then the blade lifts a pack of sheets aimed at forming a ream.

Afterwards, pushing means are introduced into the so obtained gap and move the ream out the pile, pushing it toward the machine, to be packed

According to this solution, the ream lifting and translation are automated The operator's task, if the size of the reams to be formed is to be changed, is to move manually the blade with respect to the group according to the new thickness, or to establish the opening value of the ream separating member, m case of automatic procedure

The above operation is slow and little precise, but most of all, it leaves few adjustment possibilities during the machine operation , unless mechanical systems are used, like the ones described in the Italian Patent no 1.280 258 granted on January 5, 1998

Usually, the reams produced by the above described system, are affected by a considerable error percentage, which, although remaining within a few sheets more or less, leaves a constant imprecision in the reams forming

Generally, the number of sheets constituting the just formed ream is not checked. The Italian publication B096A 000394, describes a device for verifying the size of formed reams of paper, which uses two feeler pin aimed at measuring the ream height, which is later compared with a sample value, which varies in relation to the predetermined size of the ream.

If the result of the comparison is positive, the machine continues to separate other reams, while m case of disproportion, the machine is stopped in order to adjust the selection member

SUMMARY OF THE INVENTION

The ob ect of the present invention is to propose a machine which allows to select a number of sheets as correct as possible to form a ream, without using operators and without long, complicated and imprecise operations of adjusting different sizes of reams, each time it is required.

Another object of the present invention is to propose a method, which allows to select a number of sheets for forming reams, counting them each time n an extremely short time, thus without reducing the number of reams produced m a unit time A further object of the present invention is to propose a method, which allows to verify the number of sheets selected to form the ream, thus allowing to correct possible surpluses or lacks n the block formed for that purpose.

A still further object of the present invention is to propose a method according to which the system is automatically controlled to adjust the number of sheets each time forming a ream, on the basis of the number of sheets actually selected previously. This will make possible to eliminate an error trend without the necessity to stop the machine . The above mentioned and other objects, which will become evident from the following description, are achieved by a method for selecting and verifying the number of sheets forming a selected ream of paper on an automatic machine for packaging reams of paper, said method including, after preparation of a pile of sheets a sequence of steps, according to which a pack of sheets constituting an initial ream is separated from a pile in a selection station each time and fed to a subsequent station of said packaging machine; the method includes: a) acquiring, by said machine, data necessary to define the nominal number of sheets which constitute a definite ream, the reference weight and a selection height for a definite ream to be formed and recording said data in a control unit; b) preparing selection means to select said initial ream with said selection height ; c) starting a repetitive selection cycle of said reams including: c.i) selection of a new initial ream and transferring said initial ream to a checking station; en) weighing said initial ream, so as to obtain the ream weight and comparing said ream weight with said reference weight, previously recorded; cm) m case said ream weight corresponds to said reference weight, a definite ream, obtained in this way from said initial ream, is sent to said subsequent station; civ) in case said ream weight does not correspond to said reference weight, the number of sheets constituting the initial ream is corrected m relation to the result of the previous check, so as to obtain a definite ream, which is sent to said subsequent station.

According to a second embodiment of the invention, before step a) of the method, another step is performed including counting said sheets when forming the pile and applying marks to a side of a first predetermined number of said sheets said marks being separated by a second predetermined number of sheets

The marks are used to effect an optic detection of the number of sheets selected for each ream.

According to another embodiment, a combination of weight and optic checks are performed, which allow to adjust the number of selected sheets on the basis of the same check.

Other possible variants and further characteristic features of the proposed method are reported m the dependent claims

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristic features of the invention, not appearing from what has been already said, will be pointed out m the following description with reference to the enclosed drawings, m which:

Figure 1 is a schematic view of mam stations of the initial part of an automatic machine for packaging reams, set up to carry out the proposed method;

Figure 2 shows a flow chart including a sequence of the main steps of the proposed method;

Figure 3 shows a functional and systematic diagram of an example embodiment of the invention to carry out the proposed method

BEST MODES OF CARRYING OUT THE INVENTION

The object of the method later described m detail, is not only to determine a correct number of sheets forming a ream, i.e. corresponding to the number of sheets fixed for each ream, but also to verify possible trends which can cause a progressively increasing difference between the actual number of sheets and the requested one. Thus, it is possible to correct, m real time, the number of selected sheets by acting directly on the selection means.

As it will be described later, the verify can be performed in different ways, which include comparing the weight of a ream and a weight of each sheet calculated statistically and multiplied by the number of sheets forming a ream. Another way would include measuring the ream thickness by optic instruments and data processing systems, so as to translate the obtained data into corresponding numbers of sheets. Both ways can be performed m different combinations. With reference to the above described figures, the method for determining and verifying the number of sheets forming a ream of paper is performed by an automatic machine for packaging reams of paper, schematically shown m Figure 1 and indicated with reference number 1. The reams RI are formed by taking homogenous packs of sheets from a pile 2 placed on a support or a pallet 3.

The pallet is placed on an elevator, m such a way that its position is automatically moved upwards after that each pack of sheets has been withdrawn, according to known techniques. The sheets are selected by known devices, adapted to carry out the method claimed hereinafter.

For instance, the withdrawing member includes a blade 6 or a wedge body, which is introduced between the sheets, thus separating a pack of sheets which are to constitute a ream being formed, like m techniques already known m the field.

The blade 6 or wedge body is located m the pack separation area automatically by a known device, not shown, controlled by an electronic control unit, or processing unit, which manages the whole machine operation, schematically shown in Figure 3 and indicated with 100.

In particular, the separation device of known type is capable of defining a constant thickness of the pack of sheets to be separated from the pile each time a new ream is being formed. Afterwards, the pack of sheets, aimed at forming a ream R, removed from the pile 2 in the separation station 10, is verified as regards the number of sheets, and then fed to a subsequent section 20 of the packaging machine 1. With reference to Figure 3, to carry out the proposed method, the following operations are preferably performed already during the preparation of the pile of sheets, from which the reams to be packaged are removed . measuring the height HS of the support 3, or pallet, on which the pile 2 of sheets will be formed, weighing the empty support 3 ; counting the sheets as they are produced by the cutting machine and piled; placing a mark of a color different from the piled sheets color, e.g. black on white sheets, on the side of the pile or each sheet; measuring the height HP of the obtained pile 2, taking into account the support or pallet 3; weighing the obtained pile 2, taking into account the support or pallet 3

The height HS of the support or pallet 3 is preferably measured directly, or it is known from the constructive characteristics of the support .

The same consideration relates to the weight of the empty support or pallet 3.

These two characteristics can be reported, e.g. m a coded form, on a special label 9 applied to the side of the support.

Knowing the number of strips of paper 11 put one over another during the cutting operation, it is possible to count the sheets progressively cut in a station T. Checking means 12 can be provided for detecting and correcting possible errors resulting from an accidental cut-off of one or more strips of paper 11.

The marks on the side of the pile 2 are applied on the side of the groups of sheets of paper as they are produced, by printing device 13 , suitably controlled by a control device 14 The control device 14 s connected to the checking means 12, so as to take into account possible lacks of sheets and, consequently, mark exactly the sheets which are needed each time to compose the fixed number. The marks 8 extend horizontally for a distance long enough to be clearly noted by an optic reading device e g telecamera or another type of reader

The marks extend vertically along a predetermined fixed number of sheets Nl , e g 20, and are vertically spaced apart by a predetermined fixed number of sheets N2, e.g. 30.

Then, the height and the total weight of the pile 2 situated on the support, are measured m subsequent stations U and V.

The measured height and weight of the pile 2 on the support can be inserted into the control unit by the operator, by a keyboard connected to a special terminal, neither of them shown, as commonly known, or sent to the control unit by direct connection, where this could be possible

The height and weight of the support 3 can be either inserted by the operator, or read directly on the label 9, by a suitable reader of known type connected to the control unit 100

The actual height HP of the pile 2, as well as the actual weight PP of the pile 2, without the support or pallet 3, are obtained by suitable processing n the control unit, on the basis of the parameters taken before and during the pile formation (NTP = number of sheets counted during the pile formation) .

Then, the operator inserts, through the above mentioned keyboard, the nominal number of sheets NO necessary to form each ream R, e.g. 250, as said in the introductory statement. Therefore, knowing the height and the weight of the pile 2, as well as the total number NTP of sheets forming the pile, it is possible to obtain a nominal value of weight and height of each sheet, defined statistically Having the above values, and having set the nominal number NO of sheets for each ream, the control unit is able to determine and record the weight PO and the selection height HO of an initial ream RI

The point, which the blade of the selection member is to be introduced into the pile 2, is set in relation to the height HO, by acting on adjustment servomechanisms, connected to the blade

Then, a repetitive working cycle constituted by a series of repeated steps, is started.

During a first step, a new initial ream RI, whose height corresponds to the correct selection height HO, is taken from the pile 2 in the selection station 10

Then, the weight PR of the new ream RI is verified m the checking station W.

In fact, the weight of the ream RI is verified and compared with the recorded value P0

The possible difference between the two values is compensated for by adding or removing sheets relation to the result of the weight check just performed.

The sheets are removed or added by a suitable device 25, which will not be described, since it can be of known type, and which adds or removes respectively the lacking or exceeding sheets, thus obtaining a definite ream R

Also the number NS of corrected reams is increased and recorded a corresponding counting device including e.g. one of registers of the control unit 100

When a selected number of similar errors, i.e. all exceeding or all lacking, subsequent in a series or prevailing within a determined number of checks, is reached, the data in the control unit correspondmg to the selection height HO of the ream RI and the reference weight PO are corrected accordingly.

Instead of intervening after a fixed number of similar subsequent errors is noted, it is possible to prepare a suitable algorithm, which determines, in relation to various parameters, the moment, in which the data corresponding to the sample ream should be changed in the control unit 100.

Consequently, the selection point of the selection blade on the pile 2 is adjusted m relation to the new value HO. The definite ream R is sent to subsequent stations 20, which the packaging is completed m known way

The intervention on the data recorded m the control unit 100 allows to correct the error trends before it provokes an unacceptable variation of the number of selected sheets with respect to the nominal value NO .

Then, a subsequent ream Rl is withdrawn and the cycle is repeated with the reams selection parameters automatically adjusted in real time.

Another embodiment of the previously described method allows to obtain bigger precision and certainty defining the number of sheets to be selected, using the marks reported on the side of the pile 2 during the formation thereof.

According to this embodiment of the proposed method, instead of checking the number of sheets by weighing the ream Rl , the number NR of sheets constituting a ream is actually counted by an optic reader 5.

The optic reader 5 can include a telecamera or another known reading device, which frames the side of the selected ream Rl and sends an image to the control unit 100 The control unit 100 processes the received data by a special software.

The processing determines first of all the number of the entire marks present along the side of the ream Rl . Supposing five entire marks detected along the ream side, it would be known immediately that the exact number of sheets between the upper border of the upper mark and the lower border of the lower mark is 220. This number results from the sum of the result of the multiplication of the sheets indicated by each entire mark, twenty, by the number of entire marks, five (20 x 5 = 100) , and the multiplication of the number of sheets comprised between each pair of entire marks, thirty, by the number of spaces comprised between all the entire marks, in this case four (30 x 4 = 120) .

The result obtained by the sum of the previous results is (100 + 120 = 220) .

Now it is necessary to estimate the number of sheets outside the detected interval. Four cases can occur: 1. the top of the ream Rl is distant from the upper border of the upper entire mark by a number Nx of sheets, while the bottom of the ream Rl is distant from the lower border of the lower entire mark by a number Ny of sheets (no partial marks) ; 2. the top of the ream Rl divides a mark situated over the upper entire mark, while the bottom of the ream Rl is distant from the lower border of the lower entire mark by a number Ny of sheets (one partial mark at the top) ;

3. the top of the ream Rl divides a mark situated over the upper entire mark, while the bottom of the ream Rl divides a mark situated under the lower entire mark (two partial marks) ,-

4. the top of the ream Rl is distant from the upper border of the upper entire mark by a number Nx of sheets, while the bottom of the ream Rl divides a mark situated under the lower entire mark (one partial mark at the bottom) .

In the first case, the telecamera and the software processing the image taken thereby, are able to define the measures of the intervals which separate the lower and upper borders of respectively lower and upper marks, from the bottom to the top of the ream Rl .

After the above measures have been taken and knowing the distance between the two marks and the number of sheets comprised therebetween, it is possible to define with extreme precision the number of sheets corresponding to such distance, by a very simple mathematical operation.

For instance, fifteen sheets between the upper border of the upper entire mark and the top of the ream, and twenty four sheets between the lower border of the lower entire mark and the bottom of the ream.

The result is that the ream is composed of 259 sheets (220 + 15 + 24) .

In the second case, the same procedure as in the previous case is followed at the bottom of the ream, and e.g. 5 sheets are noted.

A partial mark is situated at the top of the ream.

Therefore, the software counts thirty sheets, i.e. the ones comprised between the upper border of the upper entire mark and the lower border of the top partial mark. The number of sheets resulting from the comparison of the extension of the partial mark with the extension of one of the entire marks, is added to the number of sheets counted by the program.

Knowing the number of sheets included along the entire mark, it is possible to define precisely, by the same simple mathematical operation, the number of sheets corresponding to the partial mark, e.g. four.

Therefore, the total number of sheets in the ream Rl is 259 (220 + 5 + 30 + 4) .

In the third case, it is necessary to take into consideration the detection of only four entire marks, or, otherwise, an exceeding error, difficult to happen, would occur. Thus, four entire marks give as immediate result (4 x 20 + 3 x 30 = 170) .

Having detected two partial marks at the top and at the bottom of the ream, the software adds immediately sixty sheets to the already obtained sum (two intervals between the entire and partial marks) .

Then, the previous procedure, like for the two partial marks, is repeated, counting e.g. eight sheets in the top partial mark and six sheets in the bottom partial mark.

The total sum is 244 sheets (170 + 60 + 8 + 6) . The fourth case corresponds to the second case with the reversed situation top - bottom of the ream.

After having detected the possible differences, they are corrected by adding or removing sheets until a definite ream R, of the nominal number of sheets 250, is obtained. Afterwards, the definite ream R is sent to the subsequent stations 20 and the cycle ends, thus beginning the selection of a new ream Rl.

According to a further embodiment of the proposed method, the just described optic check is alternated with a fixed number of checks performed only by weighing.

The purpose of this mixed procedure is to use the optic check only as correction of those data used for the usual reams weight check.

The interval of actuation of the optic check can be set by an algorithm, instead of a fixed number of reams weight checks. The algorithm, in relation to various parameters sets the moment, in which the optic check should be actuated, instead of, or after the weight check.

If, after a predetermined period of time, the optic check detects an error tendency with a constant direction, e.g. sheets always exceeding or always lacking, after a certain number of similar errors, subsequent in a series or prevailing in a determined number of checks, the control unit 100 sets a correction of reference parameters recorded therein .

This certain number of errors is previously fixed or established by a suitable algorithm, which takes into consideration various parameters .

For this purpose, the ream R is weighed again after the correction of the number of sheets forming it, and the reference weight value PO is corrected correspondingly.

Also the reference height value H9 of the ream is corrected and the selection member 6 is relocated correspondingly.

The just described procedure is the preferred one, because of the extreme reliability it gives to the selection process.

Figure 2 shows a simplified flow chart related to the steps substantially carrying out the proposed method accordmg to the preferred embodiment.

Obviously, different combinations of the two check systems are possible, all remaining with the protective scope of the present invention.

The data required by the control unit 100 to calculate the reference weight P0 and reference height HO of the ream Rl are keyed m by the operator or sent directly by an interface (not shown) .

However, in a simplified form of the method and the device carrying it out, the operator can calculate the reference values manually and then key the data into the control unit 100. This means that the operator takes a ream formed by a required number of sheets, e.g. 250, counting them manually one by one or by an automatic counting device.

Afterwards, the operator measures the weight and the height of the ream in a way known to those skilled m the field, so that the data correspond as much as possible to the real situation of selected reams. Finally, the operator keys in the obtained data into the control unit 100 by already mentioned keyboard.

Another possible way to acquire data necessary to the machine 1, is the use of means for data transfer, such as magnetic supports, floppy disks, etc.

For example, during the forming of the pile 2, it is possible to record on a floppy disk the data concerning the number of sheets NTP constituting the pile 2, the number of sheets Nl featuring a entire mark 8, and the number of sheets N2 comprised between two subsequent marks .

Then, the floppy disk is joined to the pile 2, or to the lot of produced piles.

In this case, the operator introduces the floppy disk into a suitable floppy drive of the machine 1. The proposed method allows to use the marks 8 applied to the side of the pile, and consequently, also to the selected reams Rl, to transfer different information to the control unit 100, so as to allow more and more precise and rapid defining of the number of sheets actually removed from the pile 2. It is enough to write, according to known techniques, a coding on the mark 8.

Later, the coding will be read by the optic reader 5 and interpreted by the control unit 100.

The described method allows to achieve the objects mentioned in the introduction.

In particular, the described method allows to remove from the pile the correct number of sheets necessary to form a ream, without the operator and without long, complicated and imprecise adjusting operations, in case different reams sizes are required. Moreover, the selected sheets forming the reams are counted each time extremely rapidly, without reducing the number of reams produced in a unit time. The checking of the number of selected sheets forming a ream allows to correct possible surpluses or lacks in an automatic way.

Finally, the proposed method allows to intervene automatically on the sheets selection system, so as to adapt the quantity of removed sheets in the basis of number of sheets actually removed previously, and therefore, to eliminate a possible error trends.

The last possibility to feedback check is particularly advantageous because it allows the machine to work for long periods without the operator's interventions. It is understood that what above, has been described as a pure, not limitative example, therefore, possible variants of the invention remain within the protective scope of the present technical solution, as described above and claimed hereinafter.

Claims

1 Method for determining and verifying the number of sheets forming a selected ream of paper on an automatic machine (1) for packaging reams of paper, said method including, after preparation of a pile (2) of sheets a sequence of steps, according to which a pack of sheets constituting an initial ream (Rl) is separated from a pile (2) in a selection station (10) each time and fed to a subsequent station (20) of said packaging machine (1) , said method being characterized in that it includes: d. acquiring, by said machine (1), data necessary to define the nominal number of sheets (NO) which constitute a definite ream (R) , the reference weight

(P0) and a selection height (HO) for a definite ream (R) to be formed and recording said data a control

e) preparing selection means (6) to select said initial ream (Rl) with said selection height (HO); f) starting a repetitive selection cycle of said reams (R) including c.i) selection of a new initial ream (Rl) and transferring said initial ream (Rl) to a checking station (W) ; en) weighing said initial ream (Rl) , so as to obtain the ream weight (PR) and comparing said ream weight with said reference weight, previously recorded, cm) case said ream weight (PR) corresponds to said reference weight (P0) , a definite ream (R) , obtained m this way from said initial ream (Rl) , is sent to said subsequent station (20); c IV) in case said ream weight (PR) does not correspond to said reference weight (PO) , the number of sheets constituting the initial ream

(Rl) is corrected relation to the result of the previous check, so as to obtain a definite ream (R) , which is sent to said subsequent station (20) .

2 Method, according to claim 1, wherein when a pre-established number of discrepancies of said ream weight (PR) with respect to said reference weight (PO) is reached, said discrepancies being all exceeding or all lacking and subsequent or prevailing a determined number of checks, said reference weight (PO) is corrected, with the definite ream (R) weight being detected after the sheets correction, and also said selection height (HO) is corrected in relation to the above acquired data.

3. Method, according to claim 2, wherein said predetermined number of discrepancies is established by a predetermined algorithm.

4. Method, according to claim 1, wherein said reference weight (P0) is obtained statistically by dividing the weight of said pile (2) by the number of sheets constituting it and finally, multiplying the result by the nominal number (NO) of sheets constituting the definite ream (R) .

5. Method, according to claim 4, wherein the weight of said pile (2) is obtained by measuring the weight of an empty support (3), on which said pile (2) is formed, and subsequently measuring the total weight of the pile with said support, and determining the difference between the two measures

6. Method, according to claim 4, wherein the reference weight (PO) of said definite ream (R) is obtained by counting the number of sheets corresponding to said nominal number of sheets (NO) and weighing the so obtained ream, said reference weight (PO) being keyed into a control unit by the operator using data introducing means .

7. Method, according to claim 1, wherein said selection height (HO) is defined by said machine (1) in relation to directly acquired data including the height (HP) of the pile (2) and the number of sheets (NTP) constituting said pile (2) .

8. Method, according to claim 1, wherein said selection height (HO) is defined by said control unit (100) in relation to directly acquired data including the height of the pile situated on the support (3), the height of said support (3), and the number of sheets (NTP) constituting the pile (2) .

9. Method, according to claim 1, wherein said selection height (HO) is defined by counting a number of sheets corresponding to said nominal number of sheets (NO) and measuring the height of the so obtained ream, with said selection height (HO) being keyed into said control unit (100) directly by the operator using data introducing means .

10. Method, according to claim 1, wherein said nominal number of sheets (NO) , which constitute a definite ream (R) is input into said control unit (100) directly by the operator using data introducing means .

11. Method for determining and verifying the number of sheets forming a selected ream of paper on an automatic machine (1) for packaging reams of paper, said method including a sequence of steps. according to which the sheets are first cut and piled on a support or pallet (3) , so as to form a pile (2) , and subsequently packs of sheets are selected one by one from the pile (2) in a selection station (10) and fed to a subsequent station (20) of said packaging machine, each of said packs constituting an initial ream (Rl) ; said method being characterized in that it includes: a) counting said sheets when forming the pile (2) and applying marks (8) to a side of a first predetermined number of said sheets (Nl) , said marks being separated by a second predetermined number of sheets

(N2) ; b) acquiring, by said packaging machine (1) , data necessary to define at least one reference feature

(P0,N0) of a definite ream (R) to be formed; c) preparing selection means (6) to select said initial ream (Rl) with a selection height (HO) defined in relation to said acquired and recorded data; d) starting a repetitive cycle of selection of said reams (R) including: i. selection of a new initial ream (Rl) and transferring said initial ream (Rl) to a check station (W) ; ii. detecting at least one physic feature (PR,NR) of said initial ream (Rl) and comparing it with said reference feature (PO,N0), recorded previously; iii. in case said physical feature (PR,NR) corresponds to said reference feature (P0,N0), a definite ream (R) , obtained in this way from said initial ream (Rl) , is sent to said subsequent station (20) ; iv. in case said physical feature (PR,NR) does not correspond to said reference feature (P0,N0) , the number of sheets constituting the initial ream (Rl) is corrected in relation to the check result, so as to obtain a definite ream (R) , which is sent to said subsequent station (20) .

12. Method, according to claim 11, wherein said reference feature is equal to the nominal number of sheets (NO) contained in said definite ream (R) , and said detected physical feature is constituted by a number of sheets (NR) obtained by counting, performed by optic reading, of said marks (8) situated on the side of said initial ream (Rl) , with reference to the number of sheets, along which each mark (8) extends and to the number of sheets included between the lower and upper borders of each mark (8) .

13. Method, according to claim 12, wherein said counting includes: optic detecting of one mark (8) situated in a vertical intermediate area of said ream (Rl) and defining the vertical extension of said mark (8) as well as the thickness of each of the sheets, obtained by dividing said vertical extension by the above mentioned first predetermined number of sheets (Nl) defined during the pile (2) formation; optic detecting said marks (8) to determine the number of all marks (8) present on the side of the ream (Rl) , said marks including entire marks, i.e. those whose extension corresponds to said first predetermined number of sheets (Nl) defined during said pile (2) formation, and partial marks, i.e. those marks whose extension does not correspond to said first predetermined number of sheets (Nl) defined during said pile (2) formation; multiplymg the first predetermined number of sheets (Nl) defined during said pile (2) formation, for each entire mark, by the number of detected marks; multiplying the second predetermined number of sheets (N2) defined during said pile (2) formation, l e those sheets included between each pair of marks, by the number of spaces included between all detected marks, entire and partial; alternative conditioned performing of one of the following detection steps : a) case no partial mark has been detected, the distances between the lower and upper borders of respectively lower and upper marks are measured, from bottom to top of the ream (Rl) , and the number of sheets corresponding to such distances is obtained by dividing said distances by said thickness of a single sheet; b) m case only one partial mark is detected on top, the distance between the lower border of the top partial mark and the upper border of said ream (Rl) is measured, and likewise, the distance between the lower border of the lower mark and the bottom of the ream (Rl) is measured, then the number of sheets corresponding to said distances is obtained by dividing the obtained distances by said thickness of a single sheet; c) case two partial marks, upper and lower, respectively, are detected, the distance between the lower border of the upper partial mark and the top of said ream (Rl) is measured, and likewise, the distance between the upper border of the lower partial mark and the bottom of said ream (Rl) is measured, then the number of sheets corresponding to said distances is obtained by dividing the obtained distances by said thickness of a single sheet; d) case only one partial mark is detected at bottom, the distance between the upper border of the top mark and the upper border of said ream (Rl) , and likewise, the distance between the upper border of the lower partial mark and the bottom of the ream (Rl) is measured, then the number of sheets corresponding to said distances is obtained by dividing the obtained distances by said thickness of a single sheet; summing the results of the measurements and the operations performed previously, to obtain the number of sheets (NR) constituting the ream (Rl) .

14 Method, according to claim 12, wherein said predetermined numbers, first and second (N1,N2) defined during the pile (2) formation, are acquired directly by said machine (1) by data transferring procedures.

15. Method, according to claim 12, wherein said predetermined numbers, first and second (N1,N2) defined during the pile (2) formation, are inserted into said machine (1) by an operator, who uses data introducing/transferring means.

16. Method, according to claim 12, wherein when a pre-established number of discrepancies correspondences of said number of sheets (NR) of the ream with respect to said nominal number of sheets (NO) is reached, said discrepancies being all exceeding or all lacking, and subsequent or prevailing in a determined number of checks, said reference height (HO) is corrected m relation to said acquired data and to the number of sheets repeatedly added or removed.

17. Method, according to claim 16, wherein said predetermined number of discrepancies is established by a predetermined algorithm.

18. Method, according to claim 11, further including: beside acquiring data necessary to determining said selection height (HO), acquiring also two reference features, i.e the reference weight (PO) and the nominal number (NO) of sheets constituting the definite ream (R) ; detecting two physical features of said initial ream (Rl) including weighing said initial ream (Rl) to obtain the weight of said initial ream (Rl) , and counting, by optic detection, the number of sheets (NR) constituting said initial ream (Rl) , said weight (PR) and number of sheets (NR) of said initial ream (Rl) being later compared with said reference weight (PO) and the nominal number of sheets (NO) of said definite ream (R) .

19. Method, according to claim 18, wherein said counting by optic detection is performed after a predetermined number of cycles, m which only the check by weighing said ream is performed.

20. Method, according to claim 19, wherein said predetermined number of cycles, m which only the check by weighing said ream is performed, is a fixed number.

21. Method, according to claim 19, wherein said predetermined number of cycles, in which only the check by weighing said ream is performed, is established by an algorithm.

22 Method, according to claim 19, wherein when a pre-established number of discrepancies of said number of sheets (NR) of the ream with respect to said nominal number of sheets (NO) is reached, said discrepancies being all exceeding or all lacking and subsequent or prevailing in a determined number of checks, said reference height (HO) is corrected in relation to said acquired data and to the number of sheets repeatedly added or removed, and the obtained definite ream (R) is weighed again, and the reference weight (P0) is corrected relation to the result of the last weighing.

23. Method, accordmg to claim 22, wherein sa d pre-established number of discrepancies of said number of sheets (NR) of the ream with respect to said nominal number of sheets (NO) , is established in relation to a predetermined algorithm.

24. Method, according to claim 18, wherein said nominal number of sheets (NO) of said definite ream (R) is inserted into said machine

(1) by data introducing means, while the reference weight (PO) is obtained statistically by dividing the weight of said pile (2) by the number of sheets constituting it and finally, multiplying the result by the nominal number of sheets (NO) constituting the definite ream (R) .

25. Method, according to claim 24, wherein the weight of said pile

(2) is obtained by weighing an empty support (3), on which said pile (2) is formed, and subsequently measuring the total weight of the pile with said support, and determining the difference between the two measures .

26. Method, according to claim 24, wherein the weight of said support (3) is acquired directly by the machine by optic reading of codified means applied to said support (3), while the total weight of the pile together with the support (3) is obtained in a weighing station (V) connected to said machine (1) .

27 Method, according to claim 24, wherein said reference weight (PO) and said selection height (HO) are determined by direct measuring a ream obtained by counting a number of sheets corresponding to said nominal number of sheets (NO) and introducing the resulting data into the machine (1) by data introducing means.

28. Method, accordmg to claim 11, wherein the reference weight (PO) of said definite ream (R) is obtained by counting a number of sheets corresponding to said nominal number of sheets (NO), weighing the so obtained ream and introducing the resulting data into the machine (1) by data introducing means.

29. Method, according to claim 11, wherein said selection height (HO) is determined by said machine (1) in relation to the acquired data including the height (HP) of the pile (2) and the number of sheets (NTP) constituting said pile (2), as well as the nominal number of sheets (NO) which are to constitute each definite ream (R) ■

30. Method, according to claim 27, wherein said selection height (HO) is determined by said machine (1) in relation to the acquired data a measuring station (U) joined thereto and including the height of the pile placed on the support (3), the height of said support (39, the number of sheets (NTP) constituting the pile (2), while the nominal number of sheets (NO) , which are to constitute each definite ream (R) , are introduced by data introducing means.

31 Method, according to claim 28, wherein the height of said support (3) is acquired directly by the machine (1) by optic reading of codified means (9) applied to said support (3)

32. Method, according to claim 27, wherein said selection height (HO) is determined by said machine (1) on the grounds of data introduced by data introducing/ transferring means and including the height of the pile placed on the support (3), the height of said support (3), the number of sheets (NTP) constituting the pile (2), and the nominal number of sheets (NO) , which are to constitute each definite ream (R) .

33. Method, according to claim 11, wherein said selection height (HO) is determined by counting a number of sheets corresponding to said nominal number of sheets (NO) and measuring the height of the so obtained ream.

34. Method, according to claim 11, wherein said number of sheets is counted during the pile (2) formation by checking devices (12), which allow to correct possible errors resulting from an accidental interruption of the feeding of one or more strips of paper (11) put one over another, and that said marks (8) are made on the side of said sheets by a printing device (13), suitably controlled by a control device (14) connected to the check means (12) .

35. Method, according to claim 11, wherein said marks (8) extend horizontally and vertically for a distance long enough to contain codified information.