Winding – tensioning – or guiding – Unwinding – With attachment to preceding material
Patent
1996-03-05
1998-07-07
Stodola, Daniel P.
Winding, tensioning, or guiding
Unwinding
With attachment to preceding material
2425557, B65H 1916
Patent
active
057756309
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a roll stand comprising a frame with a roll-holding device for two unwinding stations, which frame comprises means for joining, in a roll-changing operation, a material web, which is unwound from a roll provided with a rotating spindle, to a leading end, provided with adhesive tapes or glue strands, of a material web from another roll which is similarly provided with a rotating spindle, as well as means for cutting off the first-mentioned web and a mechanism for braking the spindles.
PRIOR ART
In production machines which operate with material in a running web from a roll, e.g. a rotary printing press, the unreeling roll is arranged in a roll stand, e.g. on a shaft, and provided with a braking device on the shaft or on the periphery of the roll, regulated such that the web tension between the roll and the production machine can be controlled. For high-speed production machines, automatic, roll-changing roll stands are used in order to increase the productivity of the machine and reduce material wastage.
Roll stands of this kind are provided with at least two roll-fixing arrangements, space being available for both an unreeling roll and at least one new roll. The automatically working roll stand is arranged such that when the unreeling roll starts to run out, the new roll is brought into rotation automatically or by push-button signal, driven by drive belts or drive pulleys abutting against its periphery. The leading end of the new roll is lightly fixed to underlying winding turns and prepared on the top side with a glue coating, double-sided adhesive tape or similar. In effecting the joint between the unreeling roll and the new roll, the paper webs are brought into mutual contact with the aid of a brush and/or a roller and, when the leading end of the new roll is stuck fast to the unreeling material web, a severing knife is brought into operation and slices through the web of the previously unreeling roll. The new roll is now joined to the paper web.
To enable the above-mentioned to work, an accurate synchronization is required between the speed of the running-off web and the peripheral speed of the new roll. This can be achieved, for example, with an electronic comparator system in such a way that the peripheral speed of the new roll is measured, which speed is compared with a corresponding signal from, for example, the main shaft of the production machine. By virtue of other automatic devices, the peripheral speed of the new roll has to be brought in line with that of the unreeling web.
In our patent GB 2 033 347 B, a compact roll stand is described having two roll fixtures in the form of two spindles seated on a rotatable frame. A roll is unwound in a front unwinding position until its diameter has reached a certain maximum measure. The unwinding roll has hereupon obtained a sufficiently small diameter to be accommodated in a rear unwinding position, whereupon the frame is consequently rotated by half a turn. The front unwinding position herein becomes vacant for the installation of a new roll. Prior to the web in the rear unwinding position being joined to the web of the new roll, the new roll is accelerated with the aid of a drive wheel acting against the periphery of the new roll until the respective web speeds coincide. The webs are hereupon joined, whereafter the web of the rear roll is severed with a knife designed for that purpose. The roll in the rear unwinding position is subsequently braked, as a rule, to a standstill. In the said roll stand there is a brake which constantly regulates the web tension such that no jolts occur in the web. The brake acts upon transmissions which transfer the braking effect to the spindles. A freewheel hub seated in each spindle allows the braking effect only to reach that of the spindles which is rotating the fastest.
BACKGROUND TO THE INVENTION
In new production machines of the above-specified type, there is now a desire to increase the web speed and increase the diameter of the roll sizes, whilst in all re
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Back Stefan
Hogberg Hans
Amal Aktiebolag
Rivera William A.
Stodola Daniel P.
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