Advancing material of indeterminate length – With material-responsive control means – To position material laterally
Reexamination Certificate
2000-11-07
2002-09-17
Mansen, Michael R. (Department: 3654)
Advancing material of indeterminate length
With material-responsive control means
To position material laterally
C226S185000, C226S187000, C226S190000
Reexamination Certificate
active
06450381
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a device having independently rotating axially aligned rollers for guiding a transversely stable web of material. More specifically, the invention relates to a device and method for guiding a web of paper, cardboard, corrugated cardboard or plastic material.
2. The Prior Art
A device for guiding a web of material with transverse stability is known from EP 0 519 261 B1. This device comprises a plurality of rollers that are transversely spaced from each other in relation to the direction of the material web. These rollers are supported by a fork that can be swiveled by a servo-actuator (or servo-drive) about a swivel axle extending vertically in relation to the material web. By swiveling the rollers, it is possible to align the axles of the rollers at an acute angle in relation to the direction in which the material is running, thereby exerting a lateral force on the material web to guide the material web. In order to achieve an adequate guiding effect, it is necessary to force the rollers against the material web with adequate force. To accomplish this, a stationary support is provided on the opposite side of the material web. This known device for guiding a transversely stable web of material has been successfully employed in practical applications where the required lateral guiding forces are low. However, it has been found that these known devices need improvement because the cutting blades or rifling devices exert a high lateral force on the web. This prevents the rollers from tilting with adequate speed into their nominal positions, even with highest possible contact pressure and maximally inclined positioning.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a device that offers an improved guiding effect, and which can be employed with cutting blades or rifling devices.
Another object of the invention is to provide a method of guiding a material web that allows rapid adjustment in the event the web runs astray.
These and other objects are accomplished by providing a device having a plurality of rollers that are pressed against the material web. These rollers are opposed by a plurality of counter rollers. Both the rollers and the counter rollers are rotatably supported, independently of each other, so that the rollers offer nearly no resistance to the material web. The rollers and the counter rollers are disposed transverse to the running direction of the web and are pivotally mounted. The rollers swing about an axle that is aligned substantially vertical in relation to the plane of the material web, so that when the rollers and the counter rollers are displaced and swiveled, they exert a guiding force on the material web. Since the material web is held between the rollers and the counter rollers by a clamping grip, relatively high holding forces can be achieved without obstructing the run of the material by excessive friction. This is contrary to a fixed support, which hinders both the run of the web and its guidance due to the frictional forces acting on the material web. The counter rollers support the effect of the rollers because they are capable of being displaced and swiveled, therefore an unexpectedly high lateral guiding force can be applied to the material web. If this device is disposed on a cutting blade, or on a rifling device, it is possible to adjust the lateral force exerted on the material web by the cutting blade or the rifling device, allowing the material web to be almost completely utilized. The number of rollers and counter rollers employed is dependent upon the width and physical properties of the material web, therefore the number varies depending on the given case of application. For instance, webs of corrugated cardboard can handle only low contact pressure without being permanently damaged. However, any excessive width of the rollers leads to undesirable shearing forces when the rollers are swiveled. Such shearing forces act on the material web and may damage it. In the present case, it is favorable to employ several rollers and counter rollers that are axially aligned and rotated independently of each other. When the rollers and the counter rollers are swiveled, the roller located in the inner circle will rotate slower than the roller located in the outer circle, which keeps shearing forces low.
If the material web is separated crosswise by a cutting device, the outgoing trailing end piece and the incoming leading end piece of the material web are not kept in their positions. However, the clamping grip applied by the rollers to the center of the web, provides a safe guiding effect so that the severed ends can be guided in the correct way. This means that such end or head pieces of the material web can be completely utilized, so that the collected waste is reduced. This increases the economy of the overall production.
Since the counter rollers are intended to support the guiding effect of the rollers, it is advantageous if the rollers and the counter rollers are synchronized in relation to each other. The adjustment of each of the rollers and counter rollers can be accomplished by a servo-actuator, in which case the servo-actuators are synchronized with each other via suitable synchronizing means. However, it is simpler if the counter rollers are actively connected with each other via a gearing, preferably a lever system. In this case, the rollers and the counter rollers are adjusted by a common servo-actuator and in a synchronous manner. Furthermore, since only one servo-actuator is required, control of the swiveling unit is simplified.
To apply adequate pressure to the web, irrespective of the thickness of the web, the rollers are adjustably set against the material web. Accordingly, the rollers can be swiveled about an axis that is aligned approximately vertical to the plane of the material web, and which is vertically adjustable in relation to the plane of the material web, so that the rollers have two degrees of freedom. The counter rollers are pivotally mounted in such a way that they can be swiveled only about a fixed axis, so that the counter rollers are not adjustable perpendicular to the plane of the material web. The counter rollers have only one degree of freedom. This ensures that the material web does not move vertically in relation to the plane of the material web, irrespective of the contact pressure adjusted for the rollers. This is important, especially in connection with webs of corrugated cardboard, because such webs should be guided in one plane without any reversing of the web in order to avoid damage to the web.
Swiveling the counter rolls about their axis of swivel simultaneously causes a displacement of the counter rollers, crosswise in relation to the running direction of the web. Such shifting results in an effective correction of the travel of the web.
Therefore, the counter rollers are capable of supporting the guiding effect of the rollers in the best possible way. It is advantageous if the counter rollers are pivotally mounted, swinging about a common axle. This will assure that the rollers and the counter rollers will oppose each other when they are in any position of swivel, so that the material web is always optimally held in the clamping grip.
Since the rollers are set against the counter rollers with substantial pressure, buckling can occur within the zone of the rollers especially at the head of new material web. As the material web is generally separated in places where it is spliced, web accumulation and buckling occurs frequently during the production process. Therefore, it is advantageous if at least one of the rollers or counter rollers is rotationally driven, so that they exert an advancing force on the web, and buckling of the material web is avoided.
It would be advantageous to drive several or all rollers or counter rollers. However, if the rollers were rigidly coupled with a common rotational drive, the individual rollers could no longer rotate independently of each other at differ
Ernst Thomas
Kaczmarek Johannes
Löffler Harald
Collard & Roe P.C.
Erhardt + Leimer GmbH
Mansen Michael R.
Pham Minh-Chau
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