Cutting – Means to drive or to guide tool – With simple oscillating motion only
Reexamination Certificate
1997-04-15
2001-01-16
Rada, Rinaldi I. (Department: 3724)
Cutting
Means to drive or to guide tool
With simple oscillating motion only
C083S424000, C083S436100, C083S649000, C083S949000
Reexamination Certificate
active
06173636
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for the cutoff of a fiber material web, such as a web for paper or cardboard, in a paper machine such as a paper-making machine, rewinder, coater and/or rotary slitter.
2. Description of the Related Art
A cutoff apparatus as described above may be configured with a machinewide knife that extends transverse to the direction of paper travel (see, e.g., DE 38 15 277). The cutting edge of the knife according to DE 38 15 277 has a large distance from the impact point of the cutting edge to the splice on the splicing roll. As a result, an excessively long paper remnant, or paper tail, remains behind the splice after cutoff of the material web and gluing it to a new web. This leads to breaks, for example in a follow-on coater, notably with thin paper grades. Furthermore, the apparatus according to DE 38 15 227 has the further disadvantage that a serrated blade is used, as a result of which the web undesirably has a serrated cutoff edge.
DE-U-94 13 363 shows an apparatus for cutoff of a traveling material web. The apparatus is equipped with a cutoff knife heavily slanted opposite to the direction of web travel and avoids the latter of the aforementioned disadvantages. The angle occurring during the cutoff process between cutoff knife and material web is with the object according to DE-U-94 13 363 smaller than 45 degrees. At low web velocities, a cutoff edge which is extensively straight across the material web can be achieved with it, but, especially with high web velocities, >1500 m/min, the measures according to DE-U-94 13 363 are no longer sufficient to achieve the desired reliability of operation. A factor in addition to the known problems with the above high web velocities is that the cutoff velocity of the cutoff knife is mostly insufficient to achieve a non-serrated cutoff.
What is needed in the art is a cutoff apparatus which overcomes the disadvantages that occur at high web velocities with the prior-art apparatuses.
SUMMARY OF THE INVENTION
According to a first embodiment, the cutting edge of the knife disposed underneath the material web is in the inoperative position located in the gore between the paper web and a load roll, spaced slightly from a nip formed by the load roll and a roll. This creates the advantage that the material web remnant which after web cutoff enters the nip, e.g., a splicing nip, is very short.
The invention provides for coordinating with the cutoff knife an actuator that comprises at least one impulse exchanger. Achieved with the use of such actuator, as compared to the actuators known heretofore, is the advantage of a non-serrated cutoff at very high web velocities.
According to the invention, the impulse exchange may take place mechanically or pneumatically. The impulse exchanger produces a collision, or impulse exchange, between two masses. As is evident from the following formula for a mechanical impulse generator, it is especially advantageous for the mass of the cutoff knife to be very slight,
V
2
=
2
m
1
×
V
1
m
1
+
m
2
where V
2
is the velocity of the cutoff knife with the mass m
2
after the collision, and V
1
is the velocity of the striking mass m
1
. With m
2
being much smaller than m
1
, all that can be achieved in the most favorable case is a cutoff knife velocity twice as high as the velocity of the striking mass.
As mentioned already above, a pneumatic impulse generator may also be employed; it uses a directional flow—for example compressed air—that is directed at the cutoff knife and accelerates it by exchange of the flow impulse.
Moreover, the acceleration of the cutoff knife can be aided when the actuator features in addition to the described impulse generators an energy store, for example a spring or store of compressed air. The energy stored in these systems is upon knife actuation released abruptly and converted to kinetic energy of the cutoff knife.
Of particular advantage is slanting the cutoff knife opposite to the direction of web travel. A preferred embodiment provides for the angle created in the cutoff process between the cutoff knife and the material web to be less than 45 degrees. The slanting of the cutoff knife shortens the cutoff times further still as compared to prior solutions, so that the material web cutoff proceeds very quickly. For example, an escape of the web and, thus, the tendency of wrinkling is nearly precluded.
Another embodiment provides for optimally adjusting to one another, with respect to a non-serrated cutoff, the factors that influence the cutoff edge, such as the angle forming during the cutoff process between the cutoff knife and the material web, the velocity of the material web and the approach velocity of the cutoff knife.
With the present invention, the cutoff knife is by impulse exchange accelerated such that the traveling material web is being cut off at a high cutoff knife velocity.
REFERENCES:
patent: 3591279 (1971-07-01), Gardner
patent: 3702086 (1972-11-01), Moss
patent: 3717057 (1973-02-01), Takimoto
patent: 3770551 (1973-11-01), Ceroll
patent: 3847046 (1974-11-01), Schmermund
patent: 3854357 (1974-12-01), Kron
patent: 3976237 (1976-08-01), Bossons
patent: 4056024 (1977-11-01), Baert et al.
patent: 4094727 (1978-06-01), Collins
patent: 4907014 (1990-03-01), Tzeng et al.
patent: 4936942 (1990-06-01), Sollinger et al.
patent: 5146829 (1992-09-01), Wadzinski
Kaufmann Bernd
Madrzak Zygmunt
Hall Melissa L.
Rada Rinaldi I.
Taylor & Aust P.C.
Voith Sulzer Papiermaschinen GmbH
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