Advancing material of indeterminate length – With material-responsive control means – To regulate longitudinal movement of material
Patent
1997-05-22
1999-10-12
Mansen, Michael R.
Advancing material of indeterminate length
With material-responsive control means
To regulate longitudinal movement of material
2261182, 2424173, 2424181, B65H 2600, B65H 2024, B65H 2032, B65H 5918
Patent
active
059643900
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an arrangement for delivering a web of material from a storage reel to a process line, and also to a unit included in the arrangement.
BACKGROUND OF THE INVENTION
In the manufacture of absorbent disposable articles, such as diapers, sanitary napkins and incontinence guards, a continuous web of material is conveyed through a process line, this material being either plastic film or nonwoven material. Various operations are performed in the process line, such as the placing of one or more absorbent cores on the web, the application of elastic, the application of an outer casing sheet, etc. Individual articles are separated from the continuous web of article blanks in a terminal stage of the process. In order for this process to proceed smoothly without interruptions, it is very important that the tension in the delivered web is constant at its point of delivery.
The web delivered to the process line is taken from storage reels, which are carried in pairs by a reel stand which includes means for splicing the tailing end of the web on one reel with the leading end of the web on the other reel, so that web material will be delivered continuously to the process line. These reel stands are often provided with units which are intended to ensure that the tension in the web leaving the reel stand is constant, even during the process of splicing together the webs of the old and the new reels while accelerating the new reel. It has been found that even though the tension in the web leaving the reel stand has a predetermined value, the web tension will vary at the point of its delivery to the process line, particularly when the reel stand is located at some distance from the delivery point, this variation being due to the inertia of the supporting rollers which guide the web in the space between reel stand and process line.
SUMMARY OF THE INVENTION
The object of the present invention is to provide means whereby the tension in the web will have a predetermined value at the point of its delivery to the process line, while enabling the reel stand carrying the web to be located far away from this point.
This object is achieved with an arrangement of the kind defined in the introduction which is characterized by a web tension control unit which is placed at a distance from the storage reel and in the immediate proximity of the process line. This enables the reel stand to be located in a place which will facilitate service and reel exchanges, without needing to the distance between the stand and the process line into consideration.
According to one preferred embodiment of the invention, the unit includes a distributing roller, which ensures that the web delivered to the process line will not contain wrinkles, pleats or folds.
The invention also relates to a unit for controlling the tension in an outgoing web which passes through the unit, this unit including a spring-tensioned or spring-biassed dancing or jockey arm which is pivotal about a fixed axle and which is intended to support a loop in the web, said unit being characterized in that the spring-biassing force acts in a direction opposite to the force of gravity. This arrangement enables the changes that occur in the torque acting on the dancing arm as the dancing arm rotates to be balanced by suitable geometry, so that web tension will be essentially unaffected by the rotational position of the dancing arm.
According to one advantageous embodiment of the invention, the unit includes a position indicator which senses the rotational position of the arm and delivers a position signal corresponding to this position, a pair of feeder rolls which are mounted at the upstream end of the unit and through which the web passes when the unit is operating, and a control means which receives the position signal from the position indicator and adjusts the rotational speed of the pair of feed rolls in accordance with this signal. A distributing roll is mounted downstream of the pair of feed rolls and upstream of said means
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B.o slashed.rresen Harald E
Nyren Terje
Mansen Michael R.
SCA Hygiene Products AB
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