DE68918468T2 - Device for monitoring 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

The invention relates to a winding device for producing small rolls or logs of paper. In particular, the invention relates to a winding device according to the preamble of claims 1 or 2.

For the production of logs or rolls of paper of relatively small diameter from rolls of large diameter produced on a papermaking machine, equipment and devices have been developed for the automatic production of such logs and rolls at high speed.

Relevant patents relating to the background of this type of paper rewinding machines and processes are US patents 3,869,095 and 4,327,877 and 4,422,588.

In the manufacture of these logs or rolls, the paper web fed into the machine varies quite often in basis weight, diameter, surface properties, and the like, and it is also important that the manufacturer supplies the exact number of sheets or usable units in each of the rolls obtained.

All this must be achieved while the outside diameter of the roll remains within predetermined limits, generally dictated by the wrapping and packaging equipment as well as by the size of the holders or dispensers on which the finished roll is used by the consumer. The core on which the paper is wound can also be Diameters vary, and this creates a further problem for the manufacturer in keeping the outside diameter of the finished roll constant within predetermined limits.

It may be important for economic and commercial reasons that the length of paper wound on the roll, the number of sheets or usable units on the roll and the outside diameter of the roll are controlled as accurately as possible. The device according to the invention provides such a facility.

The invention relates to papermaking machines and in particular to rewinders, that is to say machines fed with one or more large rolls or with a roll of two-ply paper to produce logs or rolls of paper of relatively smaller diameter. These "logs" are then cut perpendicular to their axes to obtain small rolls of paper for use as toilet paper, kitchen towels or similar purposes. In these machines it is convenient and sometimes inevitable to obtain a precise diameter of the roll so that the small rolls meet the requirements of subsequent operations such as cutting and packaging, as well as practical requirements such as feeding into toilet paper dispensers.

It is also appropriate (or even necessary) that the exact diameter is obtained with an exact and predetermined length of paper or with an exact and predetermined number of sheets (if the paper is perforated to pull off sheets of equal length), again for commercial reasons and in order not to exceed the desired paper length according to economic requirements.

A special requirement is to maintain the length (i.e. number of paper sheets) or weight of the small roll and to keep the diameter of the small rolls constant even if the properties (such as basis weight or diameter or surface finish) do not remain constant.

The device in question ensures the control and correction of the production in order to obtain uniformity of the above-mentioned properties.

It is therefore an object of the invention to provide a device for controlling the production of rolls or "logs" of paper produced by a winder fed with large rolls or two-ply rolls of paper, in order to ensure in particular the exact overall diameter and the paper length and/or the paper weight within predetermined limits.

From the document JP-A-59143837 a winding device is known which comprises: a press roll which exerts a pressure on the small roll being wound up and is movable in order to increase the diameter of the small rolls; length sensing means for detecting the length of the web wound up on the small roll; and diameter sensors for detecting the diameter reached by the small roll. This known winding device is suitable for the production of quite large rolls of paper webs, in which the winding parameters and in particular the tension of the web can be changed during winding. Starting from an average thickness of the web, a preset desired density of the roll and a preset diameter, this known winding device determines the instantaneous diameter and the instantaneous paper length during the winding of each individual roll. From the data determined, a microcomputer calculates the actual instantaneous winding density and automatically changes the tension in the web in order to modify the winding tension and thus the winding density.

This mode of operation is not possible in winding devices where the winding time is between two and three seconds.

In order to achieve the above-mentioned objects, a first embodiment of the winding device according to the invention comprises:

- means for adjusting the final web length on the roll to be formed;

- means for adjusting the final diameter of the small roller;

- a logic circuit for comparing the preset final diameter with the detected final diameter and the preset length with the actual detected length wound on the small final reel;

- a correction circuit for changing the pressure value generated by the press roller at the end of the winding of the small roll and before starting to wind a new small roll.

In this first embodiment, the pressure of the press roll is varied if it is necessary to obtain logs with a predetermined diameter and a predetermined wound paper length.

In some cases it is necessary that the weight of the roll is maintained within a predetermined range. Based on the same inventive concept, a second embodiment of the inventive winding device provides:

- Weight sensor means for determining the final weight of the small roll;

- means for setting a desired final diameter of the small roller;

- means for setting a desired final weight of the small roll;

- a logic circuit for comparing the preset final diameter and final weight with the determined diameter and determined weight of the finished small roll;

- a correction circuit for varying the pressure value exerted by the press roll at the end of the winding of the small roll and before the start of the winding of a new small roll.

The diameter sensor means can be assigned to the small button and are activated when the desired diameter is reached.

The device may comprise at least two sensors and a cam member, or an encoder for evaluating the limit positions, and thresholds for controlling fine and coarse adjustments according to the detected diameter of the roller, i.e. according to the position of the pusher assembly. Two fixed sensors may be provided having an adjustable position and spacing, and a grid may be provided on an arm for the angular displacement of the pusher to obtain the various settings by four practical and consecutive pulses. Alternatively, the diameter sensor may be arranged as an encoder measuring angular displacement of the pusher arm.

In the second embodiment, weighing means may be provided, such as a load cell, which can evaluate the weight of the log or roll as data to be used for the corrections.

The device therefore provides for the execution of a simultaneous control of the diameter and the length of the paper or the weight of the log up to the predetermined limit. Furthermore, the device provides for the exact maintenance of the diameter in the event of varying paper characteristics, either by introducing a variation in the length of the paper fed for each roll or by maintaining the length and diameter by varying the load exerted by the small pusher.

In one embodiment, the pusher load is reduced so that the roll diameter increases with the same length of wound paper. Conversely, paper can be added to the roll to achieve the desired length. by applying a greater load of the pusher to the roll in order to achieve the preset diameter with a larger amount of paper wound up.

In a further embodiment, the device allows the paper weight to be kept constant by varying the length and by maintaining the diameter by varying the press load on the formed roll.

Further embodiments are specified in the appended claims.

All operations can be carried out with the machine in operation, without interrupting the production process and successive corrections can be made until the preset and desired limits are restored.

In addition to the foregoing and other objects, further information and a better understanding of the present invention can be obtained by reference to the following detailed description, while advantageous features of the invention are set forth in the claims.

For the purpose of illustrating the invention, there is shown in the accompanying drawings an embodiment thereof which is presently preferred, although it will be understood that the various components composing the invention may be arranged and organized in various ways and that the invention is limited to the precise arrangements and organizations of the Individual parts as described and shown here are not limited.

In the drawing, in which like reference symbols indicate like parts, show:

Fig. 1 is a schematic representation of a winding device limited to the main parts for winding a paper web onto a roll;

Fig. 2 is a block diagram of the electronic parts relevant to the correction system;

Fig. 3 shows a further embodiment similar to Fig. 1; and

Fig. 4 is an explanatory circuit diagram.

Referring particularly to Figures 1 and 3, the continuously fed paper web N is transversely perforated (to produce sheets) at regular intervals by a device 1 and is rotated by a cylinder 2 to be fed to the main cylinder 3. Cylinder 3 determines the total length of the web to be wound up and contains a cutting device including a cylinder 5 which carries out the cutting of the web N.

The reference numeral 7 designates a cylinder which cooperates with the cylinder 3 and defines a space therewith, into which a tubular core, preferably made of cardboard, is inserted in a manner known per se in the direction of the arrow fA. The paper web is wound onto the core to form the roll or log BS, which is then moved away in a suitable manner in the direction of the arrow fB. Such cutting and winding arrangements are known for example from US patent specification 4,327,877. They can also comprise a so-called pusher, ie a further pressure roller 9, which is movably mounted for example on a pair of arms 12 articulated at 14. Pusher 9 can generate a suitable pressure, ie a pressing on the roller BS being formed and thus completely define the diameter of the roller.

The pusher 9 can vary the pressure exerted on the roll BS being formed and thereby compress the paper on the roll to a greater or lesser extent. The pusher assembly 9 with its support arms 12 also makes it possible to sense the diameter of the roll being formed and therefore the pusher itself can cooperate with a diameter sensor. For example, the pressure exerted by the pusher on the roll can be regulated by an adjustable weight which can be moved along arm 12 by a control screw or other device not shown.

As shown in Fig. 1, a sensor is provided for detecting the diameter, comprising a grid 16 located on the arms 12 and a viewing device 18 of optical type such as an "electric eye" at a fixed location. A simpler arrangement comprises a suitably positioned microswitch which sets the diameter that the roll BS must reach in order to meet the above-mentioned requirements. Two optical sensors may be provided which regulate the coarse and fine corrections of the contact pressure on the paper.

On the assembly of the arms 12 of the pusher 9, means are provided for adjusting the pressure exerted by the pusher 9 on the roll BS being formed. The regulator can consist of a piston-cylinder system 20 subjected to a pressure adjustable by a control system 22, which is dependent on control means operated electronically according to a suitable program. The regulator can work by increasing the pressure inside the system 20 and thus reducing the pressure applied by the pusher on the roll, and vice versa.

Fig. 2 shows an electronic block diagram with an input 31 for data relating to the desired diameter, which receives data from a sensor corresponding to that indicated by 16, 18 in Fig. 1. References 33 and 35 in Fig. 2 indicate two timers set to a longer or shorter time in order to obtain coarse and fine corrections. References 36 and 37 indicate the data input for setting the lengths, i.e. the number of meters of paper representing the limits of the permissible paper range, while reference 38 indicates the input for the actual value of the length of paper added, this input being fed by a counter 24 associated with the cylinder 3. Reference 39 indicates an electronic logic capable of receiving a card (which can be easily replaced) with the program. The reference numerals 41, 43 and 45 designate three gates which are assigned to the three outputs of the electronic logic 39 and which also receive data relevant to the diameter achieved from input 31. The gates 41 and 43 are for the Coarse corrections and gate 45 for fine correction.

From gates 41 and 43, data is fed over lines 47 and 49 to two switches 51 and 53 for increasing or decreasing the coarse correction represented by blocks 55 and 57. Switches 51 and 53 receive the correction time from timer 33, which is set for a longer period of time. The two corrections 55 and 57 can also be activated by switches 59 and 61 respectively, which are provided for fine adjustment and are connected to a timer 35 set for a shorter period of time, and by gates 67 and 69. The correction signals arrive at switches 59 and 61 over two lines 63 and 65, which come from two gates 67 and 69, which are supplied with data over line 71 from gate 45 of the electronic logic. The data designating the type of fine correction to be carried out are obtained from lines 73 and 75, which are connected to the counter 24 for determining the length of the paper passed, the counter being connected, for example, to the cylinder 3 and the diameter sensor as indicated at 16 and 18.

The device operates as follows:

When the optical sensor (or microswitch) 16, 18 is activated - either single or double - because the roll diameter has reached the desired preset value and the counter 24, which provides the information on the length of the wound paper, has not reached either of the two choices preset by 36 and 37 in the electronic logic, it is necessary to increase the length of the paper and thus the pressure of the pusher 9 must be increased so that the greater compactness of the paper rolls allows a larger quantity of paper to be collected while maintaining the roll diameter at the desired value.

If the microswitch 16, 18 is actuated and the counter 24 has already reached the upper selection limit for the permissible amount of paper, this means that there is enough paper on the roll and, as a result, the pressure of the pusher 9 must be reduced so that the desired diameter is achieved with a smaller amount of paper.

The two corrections mentioned above are achieved by the timer 33 and the activation of the switching arms on switches 51 and 53, which is caused by the gates 41 and 43, respectively.

Figures 3 and 4 show a modified embodiment in which two proximity or optical sensors 118 and 120 can cooperate with a finger 116 carried by the arm 12. The sensors 118 and 120 can be carried by a bearing 122 pivoted at 114. Similarly, the arm 12 is pivotable at 114. The bearing 122 is adjustable, for example by a screw 126, to set the position of the two sensors 118 and 120 and thus the desired diameter for the roller BS. The distance between the two sensors 118 and 120 can also be adjusted to set the tolerance of the diameters of the roller BS.

In this embodiment, the regulation system is driven by a series of pulses. In the diagram of Figure 4, the lines 201, 202, 203 and 204 can be considered as the thresholds limited by pulses obtained from the pair of sensors 118 and 120 under the influence of the finger 116, where:

- 201 corresponds to the finger (triggering) impulse of the first sensor;

- 202 corresponds to the releasing pulse of the first sensor;

- 203 corresponds to the finger (actuating) impulse of the second sensor; and

- 204 corresponds to the releasing pulse of the second sensor.

The control can be carried out by comparing the output of the counter 24 driven by the main cylinder 3 (proportional to the length of the wound paper) with pulses 201, 202, 203 and 204 by the following logical conclusions:

(1) When the preset count is reached and pulse 201 has not yet been received, a coarse adjustment is necessary to lower the pressurization and loosen the winding in order to quickly increase the diameter of the roll BS;

(2) when the preset count is reached and the pulse 201 has already been received, a fine adjustment is necessary to reduce the pressurization;

(3) when the preset count is reached and pulse 201 has already been delivered and pulse 202 has not yet been delivered, a fine adjustment is required to increase the pressure;

(4) the instantaneous pulse 202 is reached until the moment when the pulse 203 is reached, then the diameter is within the tolerance range;

(5) if the preset count is reached and the pulse 203 has already been received, a

Fine adjustment to increase the pressurization required;

(6) in the interval between pulses 203 and 204 the fine adjustment is maintained;

(7) when the preset count is reached and the pulse 204 has already been received, a coarse adjustment is required to increase the pressurization and reduce the diameter.

All this is achieved by taking advantage of the two proximity sensors 118 and 120, the distance between which defines the tolerance range TL accepted for the roller diameter, in relation to the thickness of the captured finger 116, which is actuated by the pusher 9, 12 is worn.

Another solution may involve fixing a pulse generator on the pivot pin 14 of the arm 12 of the pusher 9 and comparing its pulses with those emitted by the counter 24 on the cylinder 3, using the same criteria as those used in the solution explained above.

The above is a mode of operation in which a specific paper length is initially set and diameter adjustments are made by changing the pressure exerted on the roll by the pusher 9 to ensure that the final diameter of the rolls is at the desired value.

As soon as the captured body 116 covers the first sensor 118, a pulse takes place and the programmer compares the length of paper passed - determined by pulses from the counter 24 on cylinder 3 - with the preset length (which takes into account a constant necessary to carry out the entire change cycle) and, if the two values are substantially equal, the exchange of the rolls (an operation which takes place in any case) is actually carried out without any change in the pressing pressure being made. If, on the other hand, the two values are different (either greater or smaller), the system will initiate a change by increasing or decreasing the pressing pressure of the presser in order to correct the amount of paper in the roll. The greater the difference between the two counts (paper length and diameter of the roll BS), the greater this correction.

Alternatively, the diameter and weight of the roll can be preset and the corrections can be made by introducing changes in the length of the paper. In this case, the diameter of the roll is guaranteed, but not the length of the wound paper, which can vary by an amount of even one revolution of the cylinder 3.

Weighing systems may be provided, such as load cells like those indicated in dashed lines at C in Fig. 3 for weighing the roll which has left the position BS (where it was formed) and has moved along a chute S in the direction of the arrow fB. From the weight data it is possible to effect corrections to the pressing pressure and/or the length of paper fed to each roll.

It is further understood that the present invention may be embodied in other specific embodiments without departing from the spirit or specific features thereof, so that the embodiments described herein should be considered in all respects as illustrative and therefore not restrictive, and reference should be made to the appended claims rather than to the foregoing description in determining the scope of the invention.

Claims (10)

1. A winding device for producing small rolls (BS) from a paper web from larger rolls with a pressure roller (9) which exerts pressure on the small roll being wound up and is movable in such a way that the diameter of the small roll (BS) can increase; with length sensor means (24) for determining the length of the web wound onto the small roll (BS); and with diameter sensors (16, 18; 116, 118, 120) for detecting the diameter that has been reached by the small roll (BS), characterized by - means (36, 38) for adjusting the final web length on the roll to be formed; - means (39) for adjusting the final diameter of the small roller; - a logic circuit (39, 41, 43, 45) for comparing the preset final diameter with the detected final diameter and the preset length with the length actually detected at the end of the winding of the small roll; - and a correction circuit (33, 35, 51, 53, 59, 61, 55, 57, 67, 69) for changing the value of the pressure exerted by the pressure roller (9) at the end of the winding of the small roll and before the start of the winding of a new small roll (BS). 2. A winding device for producing small rolls (BS) from a paper web of larger rolls with a pressure roller (9) which has a exerts contact pressure on the small roll being wound up and is movable in such a way that the diameter of the small roll can increase, with length sensor means (24) for determining the length of the web wound up on the small roll (BS), and with diameter sensors (16, 18; 116, 118, 120) for determining the diameter reached by the small roll (BS), characterized by - Weight sensor means (C) for detecting the final weight of the small roll; - means (39) for setting a desired final diameter of the small roller (BS); - means (39) for setting a desired final weight of the small roll (BS); - a logic circuit (39, 41, 43, 45) for comparing the preset final diameter and final weight with the determined diameter and weight of the finished small roll (BS) - a correction circuit (33, 35, 51, 53, 61, 59, 57, 67, 69) for changing the pressure exerted by the pressure roller (9) at the end of the winding of the small roll and before the start of the winding of a new small roll (BS). 3. The winding device according to claim 1, wherein the correcting circuit (33, 35, 51, 53, 59, 61, 55, 57, 67, 69) enables a change in the length of the web wound on each small roll (BS), the length being within a range of allowable lengths determined by two preset values. 4. The winding device according to claim 2, wherein the correction circuit (33, 35, 51, 53, 59, 61, 55, 57, 67, 69) enables a change in the length of the web wound on each small roll (BS). 5. The winding device according to one of claims 1 to 4, in which the diameter sensors are operatively connected to the pressure roller (9). 6. The winding device according to claim 5 with two diameter sensors (118, 120) which evaluate the limit positions and control thresholds for fine and coarse adjustments of the diameter of the small roll (BS) as detected by the pressure roller (9) during the formation of the small roll. 7. The winding device according to claim 6, in which the distance between the two diameter sensors (118, 120) is adjustable, a grid or finger (116) is provided for cooperating with the sensors, and the position of the grid or finger with respect to the sensors is a function of the diameter of the small roll (BS). 8. The winding device according to claim 6 or 7, in which the pressure roller (9) is carried by an angularly displaceable arm (12) and the grid or fingers (116) are fixed on the arm, while the feelers (118, 120) are fixed. 9. The winding device according to claim 8, in which the sensors are adjustable in their position with respect to the position of the arm carrying the pressure roller (9). 10. The winding device according to one of claims 1 to 6, wherein the pressure roller (9) is carried on an angularly displaceable arm (12) and the diameter sensor is an encoder which measures the angular displacement of the arm.