Winding – tensioning – or guiding – Unwinding – With attachment to preceding material
Patent
1996-02-15
1998-01-20
Jillions, John M.
Winding, tensioning, or guiding
Unwinding
With attachment to preceding material
2425561, B65H 1918
Patent
active
057093555
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention concerns a splicing device for a continuous unwind stand, by means of which device the new machine reel brought to the unwind stand is connected at full speed with the web of the machine reel that is being emptied, which splicing device comprises a splicing roll, by whose means the web of the machine reel that is being emptied is pressed into contact with the splice placed on the new machine reel.
BACKGROUND OF THE INVENTION
In off-machine coating machines, a continuous unwind stand is used, in which the new machine reel brought to the unwind stand is connected at full speed with the tail of the machine reel that is being emptied. With modern high-speed coating machines, the splicing method is, in principle, the same irrespective of the manufacturer of the machine. To the end of the web of the new machine reel, a splice is prepared by means of a two-sided adhesive tape, which splice is attached to the face of the reel by means of pieces of fastening tape. 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 machine reel that is being emptied is pressed into contact with said splice by means of a roll or brush. The old web is cut off by means of a blade from above the splice.
At the current running speeds (1200 to 1600 metres per minute) the splicing at the unwind stand has become problematic. This is why the running speed of the coating machine is often lowered for the time of splicing. At high running speeds, the most important causes of the problem of splicing are air currents and the required high speed of movement of the splicing roll. At a high speed, a negative pressure is formed in the so-called splicing gap between the splicing roll that has been brought to the vicinity and the machine reel, which negative pressure may be pulsating if the new machine reel is non-circular or eccentric. The negative pressure attempts to pull the old web partly into contact with the splice even before splicing, and it also causes fluttering of the old web, Moreover, the negative pressure attempts to detach the tape splice from the face of the new machine reel, in which case the new machine reel "explodes" before splicing. In order that the run of the web could be controlled, a bend is needed at the splicing roll, which again requires stretching of the web when the splicing roll is hit quickly against the face of the new machine reel. Attempts are made to keep the tension peak produced by the hitting of the roll in connection with the splicing low by using a small splicing gap (8 mm to 12 mm), which produces an intensive phenomenon of negative pressure. Even the bend angle that is used currently produces a problematic tension peak in the web. At high running speeds, an even larger bend angle would be required.
Thus, in the splicing devices of a continuous unwind stand, the principal problems are the high speed of the stroke of the splicing roll, the large bending angle of the web, and the negative pressure formed in the splicing gap. The negative pressure produces detrimental fluttering, and the possibility of detaching of the tape used for splicing is very high. When a large splicing gap is used, the risk of web break is increased. Likewise, when a large bending angle is used, the risk of web break is increased. When the splicing gap is made smaller, the consequence is an increased negative pressure and the resulting detrimental effects. When the splicing gap is made larger, the tension peak applied to the web, i.e. the risk of web break, becomes higher.
At present, as the splicing device of a continuous unwind stand, a splicing roll is commonly used, which usually has a 35 mm thick soft rubber face. The core material of the splicing roll is, as a rule, steel, but it may also be of some other material, such as, for example, carbon fibre.
OBJECTS AND SUMMARY OF THE INVENTION
The object of the present invention is to provide an improvement of the prior-art splicing devices of continuous unwind
REFERENCES:
patent: 1967056 (1934-07-01), Horton
patent: 3276710 (1966-10-01), Zernov et al.
patent: 3915399 (1975-10-01), Kron et al.
patent: 4009841 (1977-03-01), Matalia
patent: 4763851 (1988-08-01), Flament
patent: 4936942 (1990-06-01), Sollinger et al.
Kinnunen Jorma
Mikkonen Silvo
Jillions John M.
Valmet Corporation
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