The invention also relates to a device according to the preamble of claim 13.

In off-machine coating machines, a continuous unwind is used in which the new machine reel brought to the unwind is connected at full speed with the tail of the expiring machine reel. The end of the web of the new machine reel is prepared in advance with a splice by means of a two-sided adhesive tape for joining the end of the web to the surface of the reel. The surface speed of the new machine reel is accelerated to a speed equal to the running speed of the machine, after which the web of the expiring machine reel is pressed into contact with said splice by means of a roll or brush. The old web is cut off by means of a knife from above the splice.

By the splicing device is meant in this connection a whole that comprises a paster roll and a web guide roll placed after it and actuators moving said rolls. Today, a paster roll usually having a thick soft rubber surface is commonly used as the splicing device of a continuous unwind stand. The core material of the paster roll is generally steel but it may also be of some other material, such as, for example, carbon fibre. The length of the splicing nip between the machine reel and the rubber- covered paster roll is of the order of about 25 mm. If the web speed is 1500 m/min, the running time of the web through the nip is only 1 ms. The linear load of the paster roll used today is generally about 2500-8000 N/m.

At today's running speeds (1200-1600 m/min), the splicing at the unwind has become problematic. For this reason, the running speed of the coating machine is often lowered for the time of splicing. One reason for splicing problems at high running speeds is the paster roll movement speed which must be high. Attempts are made to keep the tension peak produced by the hitting of the roll during splicing low by using a small splice gap (8-12 mm), which produces an intensive phenomenon of negative pressure. Even the bending angle that is used today causes a problematic tension peak in the web. At higher running speeds, an even larger bending angle would be required. Thus, in the splicing devices of a continuous unwind, the main problems are the high speed of the stroke of the paster roll, the large bending angle of the web, and the negative pressure produced in the splice gap. The negative pressure causes detrimental fluttering, and the possibility of the tape used for splicing being detached is very high. When a large splice gap is used, the risk of web break is increased because of the stretching the web is subjected to. Likewise, when a large bending angle is used, the risk of web break increases. When the splice gap is made smaller, the consequence is an increased negative pressure and the resulting adverse effects. When the splice gap is made larger, the tension peak applied to the web, i. e. the risk of web break, becomes higher.

With respect to the prior art relating to the splicing devices of a continuous unwind, reference can be made, for example, to FI patents FI 100323 and FI 96299, which disclose solutions in connection with the problems caused by the large bending angle of the web and the negative pressure of the splice gap, and with a view to achieving a sufficient adhesion time for gluing the splicing tape.

FI patent 100323 discloses a splicing device for a continuous unwind, by means of which device a new machine reel brought to the unwind is connected at full speed with the web of an expiring machine reel. The splicing device includes a paster roll, by means of which the web of the expiring machine reel is pressed into contact with a splice placed on the new machine reel, and at least one second roll. The paster roll and the second roll are attached to a lever device, which is mounted by means of an

articulation point placed between the shafts of the rolls such that the run of the web before splicing and the run of the web during splicing are such that the length of the web during splicing and when said rolls are in their basic positions is substantially equal. FI patent 96299 discloses a splicing device for a continuous unwind, by means of which device a new machine reel brought to the unwind is connected at full speed with the web of an expiring machine reel, the splicing device including a paster roll, by means of which the web of the expiring machine reel is pressed into contact with a splice placed on the new machine reel, and which splicing device includes at least one second roll, and in which splicing device the paster roll and said second roll are attached to a lever device, which is mounted by means of an articula- tion point placed between the shafts of the rolls such that the run of the web before splicing and the run of the web during splicing are such that the length of the web during splicing and when said rolls are in their basic positions is substantially equal.

A support wire is arranged to run over the paster roll and said second roll to form a wire nip, whereby the gluing time available for splicing is multiplied.

A pneumatic bellows is used in some prior-art practical applications as the actuator of the splicing and return strokes of the splicing sequence of the paster roll in an unwind of an off-machine coating machine. The movement speed of the paster roll stroke is controlled by air pressure and by the setting of an end absorber. The linear load between the paster roll and the new machine reel is controlled by means of a pressure reducing device of the compressed air that moves the roll, and the linear load has been set once during the initial start-up. In the tuning of the paster roll stroke, a position sensing system is made use of during the initial start-up of the splicing device, and the speed and end absorptions of the stroke are tuned based on the position information provided by said position sensing system. The setting of shock absorption is performed once during the initial start-up, and the absorbers are usually not touched after that. The changes occurring after the initial start-up are not automatically monitored, the only indicator being the operators'incidental observations based on a splicing report or splicing reliability. The problems encountered in the technique employed today include lack of control of the

alignment of the linear load, the difficult tuning of the splicing mechanism, the machine-specificity of good tuning parameters during the initial startup, the poor repeatability of tuning on the same machine (e. g. after renovation, the same performance values cannot be achieved by the same parameters), the large number of possible objects to be tuned: the pressure reducing device of compressed air for the stroke and for its return, stroke shock absorption, return stroke shock absorption, the splice gap, the resultant problems being made more difficult by the fact that a change in one tuning parameter simultaneously changes several properties.

Furthermore, the problems with the construction of the splicing devices used today include a large space requirement, a complicated structure, tailor-made components, a massive synchronizing shaft in the splicing mechanism.

Further, one problem with the applications in use is to control the acceleration of the stroke of the paster roll such that the deflection of the paster roll does not cause bouncing after nip contact.

Further, the selection of the correct linear load is problematic because, when the paster roll is in contact with the machine reel, the linear load must be sufficient in order for the splice to be successfully made. Too low a linear load causes that the tape does not stick, too high a linear load in turn may cause mechanical damage in paper or the reel.

An object of the invention is to provide an improvement over the splicing devices known today for a continuous unwind.

A more detailed object of the invention is to provide a splicing device of a continuous unwind in which the drawbacks encountered in the prior art arrangements are avoided.

One special object of the invention is to create an arrangement for improving the splicing and starting reliability of the splicing device. Another special object of the

invention is to provide an unwind splicing device that is simpler in construction. A further special object of the invention is to create an arrangement for controlling the linear load and stroke acceleration of the paster roll.

With a view to achieving the objects described above and those coming out later, the method according to the invention is mainly characterized by what is stated in the characterizing part of claim 1.

The device according to the invention is in turn characterized by what is stated in the characterizing part of claim 13.

In accordance with an advantageous feature of the invention, the acceleration of the paster roll is measured, whereby the splicing and return strokes of the splicing sequence of the paster roll can be regulated such that no bouncing is caused after nip contact, so that regulation can be accomplished during the sequence by means of a fast control system or by means of a learning system in which the pressure of the actuator that moves the paster roll is preset based on the measurement data from the preceding splicing operation. In connection with the invention, active shock absorption is advantageously used, said absorption being controlled by the splicing control system in accordance with the invention. In connection with the invention, by measuring the linear load by means of force sensors, the bouncing of the roll is concluded based on the measurement signal. The linear load level is set to be correct either by means of a quick adjustment while the roll is in contact with the machine reel or by presetting a new pressure level for the splicing stroke of the next splicing operation. The regulation and control system used in connection with the invention is based on a versatile system of sensors, so that adequate information is obtained for the regulation and control system based on the measurement results of the sensors.

When the linear load level is set with a quick adjustment, very fast components are used for regulation during the sequence. The learning system, in which the parameters of the next splicing operation are preset, in turn uses slower components.

Among other things, the following advantages are achieved by means of the invention: - Because of self-adjustment, performance is not lowered when the machine is getting old.

- It makes possible splicing recipes, for example, a different linear load for different base papers in splicing.

- It is suitable for use in connection with machine rebuilds.

- It enables the use of the running speeds used today from a splicing standpoint, i. e. the running speed is not lowered because of/during splicing.

- Better diagnostics regarding unwind splicing and the condition of the machine.

The position-and force-controlled splicing device in accordance with the invention enables better splicing. In an advantageous application used in connection with the invention there are hydraulic cylinders placed on both sides of the machine to serve as actuators, which hydraulic cylinders move the rolls of the splicing mechanism and produce the required loading force. The feedback required by regulation for position control is obtained from a sensor that measures the position of the roll and, similarly, force control obtains feedback information from a force sensor. The driving side comprises a control loop of its own and the tending side comprises a control loop of its own.

In the splicing device in accordance with the invention, the movement and the linear load on the driving and tending sides are controlled by means of software, which makes it possible to misalign the rolls in a controlled manner with respect to the machine line, whereby it is possible to rectify a sloped tension profile by slightly misaligning the web guide roll based on tension measurement. By aligning the web guide roll, it is also possible to affect the position of the web in the cross direction of the machine. The zero points of measurements can also be set by means of software, thereby also enabling alignment to be checked during running. The good software-based control of the movements of the splicing device makes it possible to maintain a desired web tension during splicing. Because of

the software-based control of the movements, operation according to the current running mode is also possible. Owing to the precise control of the linear load used in splicing, the quality of the tape splice is improved. The invention makes possible, for its part, an unwind stand that is shorter in the machine direction, thus allowing the size of the unwound reel to be increased.

In the splicing device in accordance with the invention, a roll/a pair of rolls can be checked very easily and quickly, even in a situation when the web is being run.

The alignment of the rolls to be moved and the zero point of force measurement can be checked, for example, by determining by means of stoppers or equivalent the zero point of the position mechanically and by determining the standard forces of the force sensor. From the standpoint of maintenance, different movable rolls may arouse suspicion when problems occur during production. The arrangement in accordance with the invention can be readily checked in case of possible error conditions, so that by means of a quick check a lot of downtime is saved and, at the same time, production during running is improved. In respect of the paster roll, a check can be conducted even during running and, in respect of the paper guide roll, during a short break.

The arrangement in accordance with the invention can also be combined with a known arrangement (Paperniakiizg Science and Tech7Zol0gy, Book 11, Pigme7lt Coating and Surface SiZi7 ? g of Paper, pp. 472-473, Fapet Oy, 2000), so that a position-and force-controlled hydraulic circuit including at least one hydraulic cylinder, at least one position sensor and at least one force sensor is combined with mechanical synchronization when moving the rolls.

As compared with open control, more precise control of movements and nip force can be achieved by means of the control system which is applied in connection with the invention and which utilizes closed-loop control of the machine members. Advanced regulation arrangements that make use of feedforward and feedback control make it possible to achieve results that are clearly better than

those required today. The quantities associated with the operation of the splicing mechanism can be controlled by program parameters, thus providing good repeatability in the regulation outcome. This also allows separate control of all movements and a"flying"change of parameters (movement speeds and movement accelerations, linear load), for example, according to the paper grade or speed. Operative tuning values can be readily transferred from one machine to another as compared with today's arrangement in which tuning is accomplished by screwing flow throttling devices, pressure reducing devices or the absorption of a shock absorber.

In connection with rebuilds, the mechanical system used in connection with the invention can be constructed in an existing frame structure, which means that in old machines it is possible to take all the features enabled by the invention into use.

In the following, the invention will be described in greater detail with reference to the figures of the appended drawing, but the invention is not by any means meant to be narrowly limited to the details of them.

Figure 1 is a schematic view of one application of the splicing device in accordance with the invention, in which application a paster roll and a web guide roll are connected by means of a lever mechanism.

Figure 2 shows another application of the arrangement in accordance with the invention, in which application the paster roll and the web guide roll have separate actuators.

Figure 3 is a schematic view of a third application of the invention, in which application the paster roll and the web guide roll have separate actuators and a common stationary frame.

Figure 4 is a schematic view of the control principle used in connection with the invention.

Figure 5A is a schematic view of one application for a fast control system used in connection with the invention.

Figure 5B is a schematic view of one application for a learning system, without regulation during movement, used in connection with the invention.

Figure 6A shows a schematic block diagram of an optimization arrangement for the splicing sequence of the paster roll for use in connection with the invention, which arrangement applies regulation during movement.

Figure 6B shows a schematic block diagram of an optimization arrangement for the splicing sequence of the paster roll for use in connection with the invention, which arrangement applies regulation after the stroke.

In Figs. 1-3, the parts corresponding to one another have been denoted with the same reference numerals. In Figs. 1-3, a web that is being wound is denoted with the reference sign W, a paster roll is denoted with the reference numeral 12, a web guide roll of a splicing device is denoted with the reference numeral 11 and a new machine reel from which unwinding will take place after splicing is denoted with the reference numeral 13, and an old machine reel from which the web is unwound before splicing is denoted with the reference numeral 10. A cut- off knife of a cut-off device of the web W is denoted with the reference numeral 15 and a web guide roll placed in connection with the cut-off device is denoted with the reference numeral 14. During splicing the new machine reel 13 is accelerated to the running speed and the old web is brought close to the surface of the new machine reel 13. After that the web is pressed to the surface of the machine reel 13 by means of the paster roll 12. The old web is cut off by means of the cut-off knife 15 above the splice. In addition to the paster roll 12, the splicing

device thus includes at least one other roll 11, which is an auxiliary roll and, at the same time, a web guide roll. Frame structures of the splicing device are designated by the reference numeral 30.

In the applications of the invention shown in Figs. 1 and 2, the splicing device is moved by means of a transfer carriage 26 to the vicinity of the new machine reel 13 for the time of splicing and after the splicing operation it is moved out of the vicinity of the machine reel. The strokes of the splicing sequence of the paster roll 12 during splicing are accomplished by means of an actuator, preferably a hydraulic cylinder 16.

In the application shown in Fig. 1, the web guide roll 11 is connected to the paster roll 12 by means of a lever mechanism 24. and the web guide roll 11 moves with the paster roll. The actuator which produces the quick splicing and return strokes of the splicing sequence in the application shown in the figure, is the hydraulic cylinder 16, which is attached to the frame structures 30 of the splicing device, and the web guide roll 11 is connected in connection with the paster roll 12 by means of the lever mechanism 24. A position sensor 18 and a force sensor 17 are arranged in connection with the actuator, advantageously the hydraulic cylinder 16, of the paster roll 12 for measuring the force of the splicing and return strokes of the splicing sequence and the position of the actuator 16. The speed and the force of the actuator 16 are determined on the basis of information provided by the position sensor 18 and the force sensor 17 based on active shock absorption.

In the application example of Fig. 1, active shock absorption on the hydraulic cylinder 16 is controlled by a control system (FIGS. 4 and 5) in accordance with the invention, which control system obtains the necessary measurement data from the force sensor 17 and the position sensor 18.

Fig. 2 schematically shows an application of the invention in which the paster roll 12 and the web guide roll 11 have separate actuators to accomplish the splicing and return stroke, advantageously hydraulic cylinders 16,21, and position and

force sensors 18,17 ; 27,25 coupled in connection with them. The operation of the actuator 18,21 of both the paster roll 12 and the web guide roll 11 is controlled based on the measurement results provided by the position and force sensors 18, 17; 27,25 coupled in connection with them such that the desired speed and the desired force of the actuator are achieved based on active shock absorption.

In the application example of the invention shown in Fig. 3, the paster roll 12 and the web guide roll 11 have separate actuators 16 and 21, as in the application shown in Fig. 2, and the application example shown in Fig. 3 corresponds to that of Fig. 2 in respect of its operation during the splicing sequence. Since frame structures 31,32 are stationary, the splicing device is moved to the vicinity of the reel 13 for splicing and out of the vicinity of the reel 13 for the time of running by means of the actuators 16,21, so that their stroke length shall be longer than in the application shown in Fig. 2.

In the schematic control principle of the invention shown in Fig. 4, actuators, advantageously hydraulic cylinders, on the tending side HP and on the driving side KP are denoted with the reference numerals 16 and 16'. A hydraulic valve of the hydraulic cylinder 169 16'is denoted with the reference numeral 36 and 36', respectively. A set value is obtained from a splicing recipe for a program 35, which sets a valve instruction for both the tending side and the driving side based on the measurement results provided by position measurement 18,18'and force measurement 17 and 17'.

In one application shown in Fig. 5A for a fast control system 40 for use in connection with the invention, quantities 41 which are measured are position, speed, acceleration, and force. In addition to these, the fast control system 40 uses real-time regulation as a regulation mode 42, and flow rate i. e. position, speed, acceleration, and pressure i. e. force, are used as quantities 43 to be regulated. As a typical actuator 44, the fast control system 40 uses, for example, a hydraulic

cylinder. A learning mode 45 in the fast control system 40 is constituted by a change of control parameters for the next stroke.

In the application shown in Fig. 5B for a learning system 50 for use in connection with the invention, which learning system does not use regulation during movement, quantities 51 which are measured are position, speed, acceleration, and force. Regulation 52 of this type of control system 50 includes presettable control quantities which do not have feedback. A presetting of pressure and a presetting of absorption are used as quantities 53 which are controlled. A typical actuator 54 is constituted by a pneumatic bellows and a shock absorber or by a hydraulic cylinder and a shock absorber. A learning mode 55 in the learning system 50, which does not use regulation during movement, is constituted by a change in the presetting of pressure for the next stroke and by a change in the presetting of absorption for the next stroke.

Fig. 6A is a schematic block diagram of an optimization arrangement of the splicing sequence, which arrangement is used in connection with the invention and applies regulation during movement. During the movement of a splicing stroke 60, a measurement 61 is performed, and position, speed, acceleration, and force are measured. This information 61 is passed to regulation 62 during the movement and, based on the measurement information, position, speed, acceleration i. e. flow rate, and force i. e. the pressure used are regulated in the regulation phase 62, so that the parameters of the splicing stroke 60 are already changed during its movement. Further, the measurement results 61 are used when determining a splicing response 63, i. e. position and linear load, and a change of control parameters 64 is performed based on learning for the next splicing stroke 65.

Fig. 6B is a schematic block diagram of an optimization arrangement of the splicing sequence of the paster roll, which arrangement is used in connection with the invention and applies regulation after a stroke. During the movement of a

splicing stroke 70, measurement information 71 is measured, i. e. position, speed, acceleration, and force. Before the splicing stroke 70, the presetting of pressure and the presetting of absorption have been set in a presetting phase 72. A splicing response 73, i. e. the position of the splicing actuator of the splicing stroke and the linear load produced by it are determined based on the measurement results 71, and the system learns based on the measurement results 71 and performs a change of the presetting of pressure and a change of the presetting of absorption 74 for the next splicing stroke 75.

In connection with the arrangement in accordance with the invention it is possible to place, for example, movement stoppers for mechanically determining the zero point of the position of the paster roll 12 which is moved and of the web guide roll 11, so that the positions of the rolls 129 11 can be readily checked in possible error conditions. In addition, in connection with the arrangement it is possible to determine standard forces for regulating the force of the stroke, so that the force of the stroke can also be readily checked. Since the web W is not in contact with the paster roll 12 during unwinding, the position and the force of the paster roll 12 can also be checked during running without the checking operations causing any disturbance in production.

In accordance with an advantageous additional feature, the arrangement in accordance with the invention can also be combined with a known arrangement, so that a position-and force-controlled hydraulic circuit (FIG. 4) including at least one hydraulic cylinder 16, at least one position sensor 18 and at least one force sensor 17 is combined with mechanical synchronization when moving the rolls 12, 11.

Above, only some advantageous embodiments of the invention are described and it is clear to a person skilled in the art that numerous modifications can be made thereto within the inventive idea set forth in the appended claims.