Method and device for verifying the size of reams of paper sheets

Abstract

 A device for verifying the size of reams (1) of sheets, includes at least one first feeler element (7) which touches the upper surface of a ream (1) just formed, and which is rigidly connected to a support unit (6) of a belt pressing element (5). The first feeler element (7) includes a first transducer (8) adapted to turn a value produced in accordance with the final position of the first feeler element (7) when the pressing element (5) is lowered, i.e. when the ream (1) is pressed, into a first electric signal (Se1). At its outlet, the first transducer (8) is connected to a group (9) for comparing the electric signal (Se1) with a signal corresponding to a sample value (Vc) variable in accordance with the predetermined size of the ream (1) being packaged (See figure 1).

Description

[0001] The present invention relates to a device for verifying the size of reams of paper sheet, in particular for verifying the height of these reams (especially big size reams) which are formed just before being packaged by a relative wrapping sheet.

[0002] At present, packaging machines for the above mentioned large reams (e.g. AO size used for sketches, prints and the like, thus precious and proportionally expensive articles) do not include a ream height verifying step, i.e. a check of the number of sheets, after this ream has been selected in a first station of this machine.

[0003] In fact, the only possible check currently used is indirect, i.e. realised by strips introduced automatically between two sheets at predetermined heights during formation of the pile in a station situated downstream of a shearing machine producing sheets of the required sizes.

[0004] Then, these strips allow a sight selection of the height of the ream in a proper station of the packaging machine, which can be carried out manually or automatically by automatic devices detecting these strips.

[0005] Anyway, this selection type is not error-free as far as the number of sheets is concerned, because the mechanism aimed at placing the strips do not always work correctly.

[0006] Consequently, the ream is always packaged although correct selection of the sheets number carried out previously is not made certain, and a non-detectable error margin is left in the number of sheets of the reams.

[0007] Obviously, this can lead to packaging of reams containing more or less sheets with respect to the nominal number of sheets provided for a package, when it leaves the machine; this difference cannot be accepted by the producer because of high cost of each single sheet of paper, especially of A0 size sheets mentioned above.

[0008] Therefore, for higher level automation and control of the packaging machines for large reams, the Applicant has designed and set up a device for verifying large paper reams, particularly for thickness check after formation of the reams.

[0009] The verifying operation can be carried out by an extremely precise and rapid measurement system, whose structure does not require substantial design changes of the above mentioned machine either in its entirety or in its single working stations.

[0010] Technical characteristics of the present invention, according to the above mentioned objects, will be better understood from the content of claims, given below, and the advantages of the same invention will become more evident from the following detailed description with reference to the attached drawings, which represent a merely illustrative and not limitative embodiment, in which;

• Figure 1 shows a schematic side view of the device for verifying the size of a ream, being the subject of the present invention, applied to a working station of a ream packaging machine, with some parts removed to point out others;
• Figure 2 shows a block diagram reflecting the operation of the device of Figure 1.

[0011] According to the enclosed drawings and with particular reference to figure 1, the subject device for verifying the ream size is applied to machines or apparatuses for packaging paper sheets reams 1 with a relative wrapping sheet 15 (partially seen in figure 1).

[0012] The above mentioned packaging machine includes, among other parts, a selection station were single reams are formed from a stack of sheets (the station is not shown, since it is of known type and does not form a part of the present invention).

[0013] The ream 1 just formed is moved along a horizontal line, indicated with the arrow A, by a first conveying belt 3 up to a second station 4, where it is pressed.

[0014] The second pressing station 4 includes a belt element 5 for pressing the ream 1; this element 5, situated over the first belt and facing it, is formed by a second closed-loop belt 16 mounted on a pair of pulleys 17 and supported by a relative stationary unit 6, which is a part of the machine.

[0015] The belt 16 is moved (see arrow F of fig. 1) by at least one pair of pistons 18 and 19, between a raised position, in which the belt 16 is far from the ream 1, and a lowered position, in which the second belt 16 moves towards the first belt until it touches the upper surface 2 of the ream 1 pressed in the second station 4 (seen in fig. 1).

[0016] According to a first embodiment of the subject invention, a first feeler pin 7 of the upper surface 2 of the ream 1 is rigidly connected to the support unit 6 and includes a first transducer 8 which has the aim of turning a value, produced in accordance with the final position of the first feeler pin 7 when the belt 16 is in the lowered position, i.e. a value measured when the ream 1 is pressed, into a first electric signal Se1.

[0017] At its outlet, the first transducer 8 is connected to a group 9 for comparing the electric signal Se1 with a signal corresponding to a sample value Vc, which can be set in relation to a predetermined size of the ream 1 to be packaged.

[0018] As seen in fig. 1, the first feeler pin 7 can be connected to the support unit 6 by a bushing 21, which allows height adjustment (see arrow F1) of the first feeler pin 7 with respect to the same unit in relation to the size of the reams 1 to be packaged.

[0019] In this way, it is possible to adjust the height of the first feeler pin 7 with respect to the first belt 3, suitably to the size of the moving reams 1 and thus suitably to their height, without hampering their passage.

[0020] The bushing 21 supporting the first feeler pin 7 features a radial threaded hole 22, inside which a rod 23 is screwed for blocking the first feeler pin 7 in the desired position.

[0021] In this specific case, the first belt 3 features, under its working conveying run 3a, a support and reference plate 10, which is rigid at least in proximity of the detecting area in which the first feeler pin 7 is situated; this rigid plate 10 allows a correct measurement of the thickness S of the ream 1, which would be distorted in case of flexible plate.

[0022] For this purpose and to obtain a more precise and reliable measurement, the second station 4 can be provided with a second feeler pin 11, advantageously coupled with the first feeler pin 7 and rigidly connected to the above mentioned support unit 6, situated under the first belt 3, and more precisely, in the region of the upper contact area of the first feeler pin 7.

[0023] This second feeler pin 11 touches the lower surface 10a of the support plate 10 of the first belt 3 active run 3a.

[0024] The structure of the second feeler pin 11 is identical to the first feeler pin 7 and likewise, there is provided a second transducer 12 which turns a value corresponding to the position of the second feeler pin 11 on the lower surface 10a of the support plate 10, deformed by bending when the second belt 16 presses the ream 1, into a second electric signal Se2.

[0025] At its outlet, also the second transducer 12 is connected to a group 9 for comparing the second electric signal Se2 with the first electric signal sent by the first transducer 7.

[0026] In this last case, the comparison is performed in two distinct steps, in the first one the value of the second signal Se2 is subtracted from the value of the first signal Se1, giving in result a signal Se3, which is compared, in the second step, with the above mentioned sample value Vc, which can be set in relation to the size of the reams 1. The result is shown on a suitable display 20.

[0027] In other words, the second feeler pin 11 allows to make up for, and therefore to correct, a possible detection error of the first feeler pin 7, which can occur due to possible bending of the support plate 10 below. Otherwise, this error would be summed up with the measurement of the ream 1, which would be considered incorrect.

[0028] The comparator group 9, (see also fig. 2) is connected to a control unit 13, including a software system for displaying and monitoring the reams 1 height selection and reams packaging steps.

[0029] The unit 13 controls the above mentioned first and second stations 4 and can block their operation in case the comparator group 9 sends an error signal S due to a difference between either the value of the first electric signal Se1 (in case of only one feeler pin) and the sample value Vc, or between the result signal Se3 from the comparison of the two values Se1 and Se2 (in case of two feeler pins) and the sample value Vc.

[0030] Consequently, this device allows to verify the height of the reams, with high precision, in the first station of the machine, that means before each ream enters the packaging step.

[0031] This measurement is extremely precise, since the Applicant has verified, after many test cycles, that the device can be set to detect errors within tenths of millimetres which correspond to two or three sheets missing or exceeding in the ream.

[0032] Such precision allows the producer substantial a saving and a continuous in-operation check of the ream height selection devices (if they are automatic) as well as of the devices for introducing sign strips among sheets of the reams in the stacking devices.

Claims

1. Device (1) for verifying paper sheets reams packaged by a machine including, among other parts, a first station for forming single reams (1) from a stack of sheets, said ream (1) being subsequently moved along a horizontal line (A) by a first conveying belt (3) so as to be brought to a pressing station (4),
said pressing station (4) including a belt element (5) for pressing said ream (1), supported by a relative stationary unit (6) and moving between a raised position, in which said pressing element (5) is far from said ream (1), and a lowered position, in which said pressing element (5) moves towards said first belt until it touches the upper surface (2) of said ream (1) pressed in the pressing station (4), said device being characterised in that it includes at least one first feeler pin (7) touching the upper surface (2) of said ream (1) and rigidly connected to said support unit (6) of said belt pressing element (5), with a first transducer (8) which turns a value, produced in accordance with the final position of said first feeler pin (7) when said pressing element (5) is lowered, i.e. when said ream (1) is pressed, into a first electric signal (Se1), said first transducer (8) having its outlet connected to a group (9) for comparing said first electric signal (Se1) with a signal corresponding to a sample value (Vc) variable in accordance to a predetermined size of the ream being packaged.

2. Device, according to claim 1, characterised in that
under said first belt (3) there is a support and reference plate (10) which is rigid at least in proximity of the detecting area in which the first feeler pin (7) is situated.

3. Device, according to claim 1, characterised in that
a second feeler pin (11), rigidly connected to said support unit (6), is situated under said first belt (3) in the region of said first feeler pin (7) and in contact with the lower surface (10a) of a plate (10) supporting a working conveying run (3a) of said first belt, said second feeler pin (11) being provided with a second transducer (12) which turns a value corresponding to the position of said second feeler pin (11) in abutment on said lower surface (10a) of the support plate (10), into a second electric signal (Se2), when said support plate (10) is deformed in the region of said lowered pressing area of said pressing element (5); with the
outlet of said second transducer (12) connected to said group (9) for comparing said second electric signal (Se2) with said first electric signal (Se1) sent by the first transducer (7), then subtracting the value of said second signal (Se2) from the value of said first signal (Se1).

4. Device, according to claim 1, characterised in that said comparator group (9) is connected to a control unit (13) for controlling said first and pressing stations (4) and aimed at blocking their operation in case said comparator group (9) sends a signal (S) produced by a difference between the value of the first electric signal (Se1) and said sample value (Vc).

5. Device, according to claim 1, characterised in that said comparator group (9) is connected to a control unit (13) for controlling said first and pressing stations (4) and aimed at blocking their operation in case said comparator group (9) sends a signal (S) produced by a difference between the result value (Se3) from the comparison of said first and second electric signals (Se1, Se2) and a sample value (Vc) depending on the size of said reams (1) to be packaged.

6. Device, according to claim 1, characterised in that at least one first feeler pin (7) can be moved, with possibility to adjust its position with respect to said support unit (6) so as to place it in a theoretical initial position which is function of the size of said reams (1) to be packaged.

7. Method for measuring a ream of paper sheets in reams (1) wrapping machines which include at least one first belt (3) supporting and conveying a ream (1) along a horizontal movement line (A) up to a pressing station (4), where said ream is pressed by a belt pressing element (5) situated over said first belt (3) and moving between a raised position, far from said ream (1), and a lowered position in contact with the upper surface (2) of said motionless ream (1) so as to compact said ream (1), said method being characterised in that it includes:

- contemporaneously detecting a first and a second value (Se1, Se2) by respective feeler pins (7,11) which act respectively on said free surface (2) of the ream (1) and on a lower surface (10a) of a support plate (10) situated under said first belt (3), at least when said pressing element (5) is in said lowered position;

- comparing, by a comparator group (9), said detected first and second values (Se1,Se2), i.e. subtracting the second value (Se2), corresponding to a deformation of said support plate (10), from said first value (Se1) detected on said ream (1).

8. Method, according to claim 7, characterised in that after said comparing step, said first belt (3) and said second pressing station (4) are blocked in case there is a difference between the value of a first electric signal (Se1) and said sample value (Vc), that is function of the size of said reams (1).

Drawing