IL89081A - Apparatus for controlling the production of paper rolls - Google Patents

Abstract

An apparatus for winding small rolls of paper from large rolls includes a counter (24) to measure the length of the web being wound, a presser (9) to sense and control the outer diameter of the small rolls (BS), means (16, 18) to detect and control the diameter of the small roll as it approaches the pre-determined desired diameter thereof, and an electronic logic control connected to the counter, the presser and the encoder whereby to ensure that the weight of paper and the outer diameter of the small rolls (BS) will always be within the pre-determined limits.

Description

APPARATUS FOR COSTROLUNG THE PRODUCTION OF PAPER ROMS Description of the Industrial Invention with the title; "APPARATUS FOR CONTROLLING THE PRODUCTION OF PAPER ROLLS PRODUCED BY THE REMINDER IN ORDER TO ENSURE STEADINESS OF LENGTH OE THE WOUND PAPER AND/OR OF REACHED DIAMETER" of PERINI FINANZIARIA 5. p.A., of Italian nationality, in LUCCA; filed on 29 January 1988; File No, 9318 A/88 S U M M A R Y The apparatus comprises: means for detecting the reached diameter; means for detecting the weight of a finished roll and/or of the length of paper wound at any moment; means for presetting the final diameter to be reached; as well as means for comparing the preset data with the detected ones, and correction means to keep length and diameter or weight and diameter steady.

DESCRIPTION The invention relates to plants for paper manufacture and in particular to the so-called rewinders, i.e., machines which are fed with a pair of large paper mill coils or with coils of two-folded paper, for the production of the so-called sticks or logs, i.e., rolls of paper having relatively limited diameter, which have to be subsequently cut along planes perpendicular to their axes for obtaining small rolls of paper for use as toilet paper, all-purpose wiper or for similar uses. In these plants, it is suitable and sometimes indespensable to ensure a steady diameter of the roll and thus of the small rolls obtained in order to meet requirements of successive operations, such as cutting and packaging, as well as commercial requirements. On the other hand, it is also suitable or even necessary that the desired diameter be obtained with a precise and predetermined length of paper or with a precise and predetermined number of so-called tears (when the paper is perforated to be detached in stretches of equal length), again for commercial requirements and for the need of not exceeding a certain limit of paper length according to economical requirements. A particular requirement is that of keeping the length (that is the number of tears) of the paper or the weight of the small roll, and always the diameter of the small rolls steady, while the characteristics of the supplied paper are changing.

The apparatus in question ensures control and correction of the production in order to achieve steadiness in, the above mentioned characteristics.

Substantially, an apparatus according to the invention - for controlling the production of rolls or sticks of paper produced by a rewinder fed with paper mill reels or . two-folded paper reels, especially for ensuring »* steadiness of the overall diameter along with the paper length and/or paper weight steadiness within preset limits - comprises:means for detecting the reached diameter; means for detecting the weight of a finished roll and/or the length of paper instantaneously wound; means for presetting the final diameter to be reached; means for comparing the preset data with the detected ones; and correction means.

Advantageo sly, the correction means may comprise a regulator for adjusting the pressure, i.e. the thrust exerted by a small presser acting on the roll being formed.

The diameter-sensing means may be associated with the small presser which is made to move according to the reached diameter.

The apparatus may be combined with an electronic logic able to operate a correction by means of the small presser acting on the roll being formed and driven by the adjustment means of the thrust to be exerted on said roll.

The apparatus may comprise at least two sensors and a cam member, or an encoder, for evaluating limit positions and thresholds for controlling fine and coarse adjustments according to the sensed diameter of the "stick, i.e. according to the position of the presser assembly. There can be provided two fixed sensors, which have adjustable position and interspace, and a screen member located on an arm for the angular displacement of the presser, in order to obtain the various adjustments through four practicable and subsequent pulses.

Alternatively, the diameter sensor may be developed as an encoder that measures the angular displacement of the presser arm.

According to another embodiment a weighing means may be provided, such as a load cell, able to evaluate the stick or roll weight as data to be used for corrections.

Substantially, the apparatus provides for carrying out the simultaneous control of the diameter and length of the paper or of the weight of the stick up to the predisposed limit. Moreover, the apparatus provides for keeping said diameter steady when the characteristics of paper are changing, either by imposing a change of length of the paper supplied for each roll, or by keeping the length and the diameter steady through a variation of the thrust operated by the small presser.

In a feasible embodiment, the apparatus allows to remove paper from the roll being formed by reducing the presser thrust and. thus increasing the roll diameter under the same length of wound paper; vice versa, paper »* may be added to the roll in order to reach the desired ~ length by causing a greater thrusting action of the presser on the roll,, to reach the preset diameter with a greater quantity of rolled up paper.

In a further possible embodiment, the apparatus allows the paper weight to be kept steady through a variation of the length, and by maintaining the diameter steady through a variation of the presser thrust on the roll being in formation.

All the operations can be carried out with the machine in operation, without interrupting the production process and providing for successive corrections up to the restoration of the conditions comprised within the preset and desired limits.

The invention will be better understood by following the description and the attached drawing, which shows a practical, non limitative exemplification of the same invention. In the drawing: Fig.i shows a schematic representation of a rewinder, limited to the main members for the winding of paper over a roll being in formation; Pig, 2 shows a block diagram of the electronic part relevant to the correction system; Fig.3 shows another embodiment; and Pig.4 shows an explanatory diagram.

According to what is illustrated in the attached drawings, the continuously fed paper web indicated by N, is transversally perforated at equal distances (to permit tears) by a device 1 and is deviated by a cylinder 2 in order to be fed to the main cylinder 3 which determines the length of web in transit for the winding, and on which a cutting device, including a cylinder 5, carries out the cutting of said web N. Numeral 7 indicates a cylinder intended to cooperate with cylinder 3 and defining an interspace with it, wherein a tubular core, mostly made of cardboard, is inserted - in a known manner - according to arrow fA, on which core the paper web is wound to form the roll or stick BS, which is then suitably moved away according to arrow fB. Arrangements of this kind are known per se. They comprise, generally, also a so-called presser, i.e. a further pressing roller or presser > which is movable being mounted, for example, on a pair of arms 12 articulated at 14; presser 9 is able to produce a suitable pressure, that is, a thrust on the roll BS being in formation and thus to completely define the winding seat of the same roll.

Presser 9 is capable of varying the pressure exerted on the roll BS being in formation and thereby compacting the paper which rolls up thereon. in successive coils, to a more or less degree. The presser 9 assembly, with its supporting arms 12, allows also to evaluate the diameter gradually reached by the roll being in formation and, therefore, the presser itself may cooperate with a diameter evaluating sensor.

According to the drawing, a sensor is provided for evaluating said diameter, which sensor comprises a screen 16 located on the assembly of arms 12 and at least a. sight 18 of optical type, for example, at a fixed position; more simply, a suitably positioned microswitch may be provided, which establishes the diameter that the roll BS being in formation must reach to meet the above mentioned requirements. Two sights may be provided that can operate the coarse and fine corrections of the presser thrust over the paper.

On the assembly of arms 12 of presser 9, a system is made to operate for adjusting the pressure to be exerted by presser 9 on the roll BS being in formation. The regulator may consist of a cylinder-piston system 20 supplied by pressure adjustable through a control system, generically indicated by 22, which is dependent on control means which is electronically operated according to a suitable program. The regulator may operate for increasing the pressure inside the system 20 and thus reducing the presser thrust on the roll, and vice versa.

Pig.2 shows an electronic block diagram comprising an input 31 for the data concerning the reached diameter, which data are obtained by a sensor like that indicated ~ by 16, 18; 33 and 35 indicate two timers which are set for a longer and shorter time, respectively, to obtain coarse and fine corrections, respectively. Numerals 36 and 37 indicate the data input for setting the lengths, i.e. the meters of paper representing the limits of the allowable range of paper, while numeral 38 indicates the input of the actual value of the length of the fed paper, such input being supplied through a counter associated with cylinder 3· Numeral 39 indicates an electronic logic which can receive a card containing the program which can be easily changed. Numerals 1 » 43 , 45 indicate three gates associated with the three output of electronic logic 39 and which receive also the data relevant to the reached diameter from input 31 ; gates 4 and 43 are intended for the coarse correction and gate 45 for the fine correction. Prom gates 41 and 43 , data are fed through lines 47 and 49 to two switches 51 and 53 , respectively, for the increasing respectively decreasing coarse correction represented by blocks 55 and 57, respectively. Switches 1 and 53 receive the correction time from timer 33 which is set for a longer duration. The two corrections 55 , 57 ma also be activated by switches 59 and 6 1 , provided for the fine adjustment, which are connected to timer 35 , set for the shorter time, and by gates 67 and 69. The correction operative controls arrive to switches 59 and 61 via two lines 63 and 65» respectively, coming from two gates 67 and 69 fed with data obtained via line 71 from the gate 45 of the electronic logic; respective data for the delivery of the type of fine correction to be made are obtained from lines 73, 75, which are associated to the counter 24 for detecting the length of passed paper, said sensor being combined, for example, to cylinder 3 and to the diameter sensor such as that indicated by 16, 18.

The operation of the apparatus is as follows.

As the sensor or microswitch 18 - either single or dual - is actuated because the diameter has reached the desired preset value, and the counter 24, which provides the information relative to the amount of wound paper, has not arrived at any of the two selections preset by 36 and 37 in the electronic logic, it is necessary to increase the length of paper and thus the pressure of presser 9 must be increased so that the greater compaction of the coils of paper will allow an accumulation of a larger amount of paper while maintaining the roll diameter at the desired value.

When sensor formed by the screen IP and the sinht 18 is actuated and the counter has already reached the unper selection, limit for the allowable paper length, this means that there is excess of paper in the roll, and as a consequence the pressure of presser 9 must be lowered so that the preset diameter is reached with a smaller amount of paper.

The two above mentioned corrections are achieved through timer 33 and the enabling controls on switches 51 and 53 coming from gates 1 and 43, respectively.

Figs.3 and 4 show a modified embodiment, in which two proximity or optical sensors 118 and 120 can cooperate with a screen 116 carried by arm 12.

Sensors 118 and 120 may be carried by a support 122 articulated at 114 likewise arm 12; support 122 is adjustable, for example, by a threaded stem 126 to set the position of the two sensors 118 and 120 and thus the desired diameter for stick BS. The distance between the two. sensors 118, 120 can also be adjusted for establishing the tolerance of the diameter of stick BS.

In this embodiment, the regulation system is driven by a series of pulses. With reference to the diagram of Pig.4, lines 201, 202, 203, 204 may be considered as the thresholds delimited by pulses obtained from the pair of sensors 118 and 120 influenced by screen 116: - 201 corresponds to the screening i.e. obscuration pulse of the first sensor; - 202 corresponds to the releasing i.e. abandoning pulse of the first sensor; - 203 corresponds to the screening i.e. obscuration pulse of the seco d sensor; and - 204 corresponds to the releasing, i.e. abandoning pulse of the second sensor.

The regulation may be carried out by comparing a counting driven by the main cylinder 3 (proportional to the length of wound paper) with pulses 201, 202, 203, 204, through the following logical consequences: 1) If the preset counting goes off and pulse 201 has not yet arrived, it is necessary to provide a coarse regulation to lower the presser thrust and slacken the winding in order to quickly increase the diameter of stick BS; 2) If the preset counting goes off and pulse 201 has already arrived, it is necessary, to provide a fine regulation to lower the presser thrust; 3) If the prese counting goes off when pulse 201 has already been delivered and pulse 202 has not, it is necessary to provide a fine regulation in order to increase the presser thrust; 4) The moment pulse 202 goes off and up to the moment the pulse 203 goes off, the diameter is within the tolerance rang_; ■ ) If the preset counting goes off and pulse 203 has •already arrived, it is necessary to provide a fine regulation in order to increase the presser thrust; 6) In the interval between pulses 203 and 204, the fine regulation is maintained; 7) If the preset counting goes off and pulse 204 has already arrived, it is necessary to provide a coarse regulation in order to increase the presser thrust and reduce the diameter.

All this is accomplished by utilizing the two proximity sensors 118 and 120, whose distance of application determines the tolerance field TL accepted for the roll diameter, in relation to the thickness of screen 116 carried by the arm 12 supporting the presser 9.

Another solution can be that of mounting a pulse generator on the fulcrum 14 of arm 12 of presser 9 and comparing the pulses thereof with those emitted by cylinder 3 with the same criteria as those of the preceding solution.

What has been described above relates to a kind of operation in which a certain length of paper is set beforehand, and diameter adjustments are imposed through variations of the thrust operated by presser 9 on the roll being in formation in order to bring the final diameter of the rolls back to the desired value.

As soon as screerfi16 obscures the first sensor 118, a pulse takes place: the programmer compares the length of paper passed through - evaluated by pulses" produced by cylinder 3 - with the preset length (which takes. into account a constant necessary to carry out the whole exchange cycle) and, if the two values are almost equal, the exchange (operation which always takes place in any case) is actually carried out without operating any regulation over the presser thrust. If, instead, the two values are different being either greater or smaller the system will operate a regulation respectively by decreasing or increasing the thrust of the presser in order to correct the amount of paper in the roll, and the greater is the difference between the two countings (cylinder and diameter of stick BS) , the greater will be this weight correction.

Alternatively, the diameter and weight of the roll may be preset and the corrections performed by imposing variations in the length of paper. In this case, the diameter of the roll is ensured but not the length of the wound paper, which length may vary by an amount of even one revolution of cylinder 3· Weighing systems may be predisposed such as load cells like those shown at C in Fig.3 by a chain-dotted line for evaluating the weight of the stick which has left the position BS wherein it is formed and has been moved away along the chute S; by the weight data it is possible to affect, the corrections of the presser thrust and/or of the length of the paper which has been fed to each roll.

It is understood that the drawing shows an exemplification given only as a practical demonstration of the invention, as this may vary in the forms and dispositions without nevertheless coming out from the scope of the idea on which the same invention is based. For example, the regulation of the pressure exerted by the presser on the stick, may be obtained by making a weigth slide along arm 12, through a screw control or other. 89081/2

Claims (10)

1. A rewinder for producing small rolls (BS) of paper web from larger rolls, including: a pressing roller (9) which exerts a pressure on the small roll being wound, said pressing roller (9) being movable to allow the diameter of the small roll (BS) to increase; length detection means (24) for detecting the length of web wound on said small roll (BS); and diameter detecting sensors (16, 18; 116, 118, 120) for detecting the diameter reached by the small roll (BS); characterized by - means (36, 38) for setting the final web length on the roll to be formed; - means (39) for setting a desired final diameter of the small roll (BS) ; - a logic circuit (39, 41, 43, 45) for comparing the pre-set final diameter with the detected final diameter and the pre-set length with the length actually wound onto the small roll at the end of the winding of a small roll; - and a correcting circuit (33, 35, 51, 53, 59, 61, 55, 57, 67, 69) for changing the value of the pressure exerted by said pressing roller (9) at the end of the winding of the small roll and before starting winding of a new small roll (BS).

2. A rewinder for producing small rolls (BS) of paper web from larger rolls, including: a pressing roller (9) which exerts a pressure on the small roll being wound, said pressing roller being movable to allow the diameter of the small roll to increase; length detection means (24) for detecting the length of web wound on said small roll (BS); and diameter detection sensors (16, 18; 116, 118, 120) for detecting the diameter reached by the small roll (BS); " 16 " 89081/2 characterized by - weight sensor means (C) for detecting the final weigh of the small roll (BS); - means (39) for setting a desired final diameter of the small roll (BS); - means (39) for setting a desired final weight of the small roll (BS); - a logic circuit (39, 41, 43, 45) for comparing the pre-set final diameter and final weight values with the detected diameter and weight of the finished small roll (BS); - a correcting circuit (33, 35, 51, 53, 61, 59, 57, 67, 69) for changing the value of the pressure exerted by said pressing roller (9) at the end of the winding of the small roll and before starting winding of a new small roll (BS). - 17 - 89081 /2

3. The rewinder of claim 1, wherein the correcting circuit (33, 35, 51, 53, 59, 61, 55, 57, 67, 69) provides a change of the length of web wound on each small roll (BS), said length being comprised within a range of allowable lengths defined by two pre-set values.

4. The rewinder of claim 2, wherein the correcting circuit (33, 35, 51, 53, 59, 61, 55, 57, 67, 69) provides a change of the length of web wound on each small roll (BS).

5. The rewinder of any of claims 1 to 4, wherein the diameter detecting sensors are operatively connected to the pressing roller (9).

6. The. rewinder o claim 5, including two diameter detecting sensors (118, 120) which evaluate the limit positions and control thresholds for fine and coarse regulations of the diameter of the small roll (BS) as detected by the pressing rolLer (9). during formation of the small roll.

7. The rewinder of claim 6, wherein the distance between the two diameter detecting sensors (118, 120) is adjustable, a screen (116) being provided for cooperating with said sensors, the position of the screen with respect to the sensors being a function of the diameter of the small roll (BS).

8. The rewinder of claim 6 or 7, wherein the pressing roller (9) is supported on an angularly displaceable arm (12) and the screen (116) is mounted on the arm, while the sensors (118, 120) are fixed.

9. The rewinder of claim 8, wherein the sensors are adjustable in position with respect to the position of the arm supporting the pressing roller (9).

10. The rewinder of any of claims 1 to 6, wherein the pressing roller (9) is supported on an angularly displaceable arm (12), and the diameter detecting sensor is an encoder which measures the angular displacement of the arm. COHEN ZEDEK & RAPAPO l p. O . Bex 33116 , T e l - A v iv Atto rn e y s lo r Ap p l i c ant By*