Cutting – Rotatable disc tool pair or tool and carrier – With means to permit replacement of tool
Reexamination Certificate
1998-11-25
2001-07-03
Rachuba, M. (Department: 3724)
Cutting
Rotatable disc tool pair or tool and carrier
With means to permit replacement of tool
C083S482000, C083S499000, C083S508200, C083S508300, C083S526000, C083S563000
Reexamination Certificate
active
06253652
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to web slitter machines of the type used for cutting a continuous web of material and, more particularly, to a device for locking the blades of such machines to facilitate maintenance and blade replacement.
Web slitters are cutting machines commonly employed to cut an endless web, such as a continuous roll of paper, to reduce the initial wide web into a series of narrower webs during winding or rewinding operations. A typical prior art web slitter for use in paper manufacturing is indicated generally at
8
in FIG.
1
. Such web slitters are manufactured by the Valmet Corporation of Helsinki, Finland. As is shown in
FIG. 1
, the web slitter
8
includes a top blade
10
in the form of a rotary cutting disk that is suspended from a slitter frame
9
which is attached to one or more transverse bars
11
by an intermediate slitter carriage
17
. An operator locks slitter frame
9
in position on slitter carriage
17
by manipulating handles
15
. The slitter frame
9
and the components mounted thereon, including top blade
10
, make up what is known as the top slitter assembly. The web slitter
8
also includes a bottom band
12
that is rotated by a motor
13
.
During operation, top blade
10
is positioned or “side loaded” so that it lightly engages the side edge of bottom band
12
. The leading point of contact between top blade
10
and bottom band
12
forms a cutpoint whereby the paper web is cut. As a result, top blade
10
and bottom band
12
overlap to provide a scissors-like action for cutting the web as it unwinds from a roll and is pulled through the web slitter by a take-up roll. A plurality of web slitters may be connected to create parallel paper strips of various widths.
After a period of use, top blade
10
becomes dull and requires replacement. In order to “change-out” the top blade
10
, the operator first raises the top blade
10
away from bottom band
12
, as illustrated in FIG.
1
. The top blade
10
is secured to the hub
14
of slitter
8
by a locking ring
16
. In order to remove locking ring
16
, the operator first loosens the clamping screw
20
. Then, a locking ring removal/locking tool is used to free the hub
14
. Locking ring
16
then may then be unscrewed by hand from hub
14
. Once locking ring
16
is removed from hub
14
, as illustrated in
FIG. 2
, the operator may remove top blade
10
.
Once the new blade is positioned on hub
14
, the reverse procedure is performed to complete the blade change-out process.
Currently, paper mill operations people frequently find it difficult to complete a blade change-out using the above procedure. More specifically, an operator is required to use two hands when using the locking ring removal/locking tool. One hand is used to hold the tool in engagement with the locking ring while the other hand is used to turn or apply leverage to the tool. However, the tool does not prevent the hub from rotating. The operator is thus required to hold the blade so that it doesn't turn while operating the tool. As a result, the operator must steady both the tool and blade with one hand while simultaneously turning the tool with the other hand. This task can be both difficult and time consuming.
In the operation of high speed machinery, such as in paper manufacturing, the cost of machine downtime can be very high. As a result, it is desirable to minimize the time that it takes to perform maintenance operations. One way to minimize machine downtime is to reduce the time necessary to perform blade change-outs. If a web slitter was equipped with mechanisms to prevent the blade
10
from rotating during a blade change-out, operators could perform the task more quickly and safely. As a result, it is desirable to provide web slitters that may be locked to prevent rotating during blade change-outs and other maintenance procedures.
Previous blade locking mechanisms, such as those provided by the Economy Machine and Tool Company of Green Bay, Wis. have utilized a pin with a cable attached. The operation of such mechanisms involve inserting the pin through aligned holes in the hub and slitter frame. As a result, the hub and top blade are prevented from rotating. A disadvantage of this arrangement, however, is that should the pin be left engaged when the top blade is lowered and/or used for slitting, severe damage to the slitter and injury to the worker could result. In addition, lost production could occur due to an uncut or random cut paper roll.
Another type of locking mechanism involves the use of a spring plunger that engages a hole in the hub when the plunger is extended. Such mechanisms are available from the Tidland Corporation of Camas, Wash. and the Diennes Corporation of Spencer, Mass. The operator must hold the plunger in engagement with the hole in the hub, however. As a result, this mechanism does not free up both of the operator's hands.
Accordingly, it is an object of the present invention to provide a device and method for locking a slitter blade so that an operator may use both hands to perform blade change-outs and other maintenance.
It is another object of the present invention to provide a device and method for locking a slitter blade so that blade change-outs and maintenance may be performed more rapidly and safely.
It is another object of the present invention to provide a device and method for locking a slitter blade whereby the blade is automatically unlocked when the blade is engaged for slitting.
It is another object of the present invention to provide a device and method for locking a slitter blade that is simple to manufacture and easy to use.
It is still another object of the present invention to provide a device and method for locking a slitter blade that may be used with existing web slitters.
SUMMARY OF THE INVENTION
The present invention is directed to a device for locking the radial top blade of a web slitter against rotation. A typical web slitter features a top slitter assembly that includes a slitter frame to which a hub cylinder is mounted. The hub cylinder is mounted so that it may be raised or lowered with respect to the frame. A hub is disposed in the hub cylinder so that it may freely rotate therein. The top blade of the web slitter is mounted to the hub.
The locking device of the present invention features a toggle support that is clamped to the hub cylinder of the web slitter. A toggle is attached to the toggle support by a shaft so that it may pivot. A pin holder is attached to the frame of the web slitter with screws. The pin holder is positioned adjacent to the hub of the web slitter and contains a sliding pin. The pin holder also houses a compression spring that biases the pin away from the hub of the web slitter. The hub features a notch that is sized to receive one end of the pin.
When the top blade of the slitter requires replacement, the hub cylinder is raised. Raising the hub cylinder causes the toggle support to be positioned in the vicinity of the pin holder. Next, the notch of the hub is horizontally aligned with the sliding pin within the pin holder. The sliding pin is then inserted into the notch and the togale is pivoted so that one end of the pin is abutted thereby against the action of the compression spring. As a result, the pin is secured in engagement with the notch of the hub so that the hub of the slitter, and thus the top blade, are prevented from rotating. An operator may release the sliding pin from its engaged position by pivoting the toggle back to its original position. Alternatively, due to the positioning of the toggle support on the hub cylinder and the pin holder on the frame, the toggle is removed from abutment with the sliding pin, and thus the blade is automatically unlocked, when the blade is lowered into the cutting position.
REFERENCES:
patent: 3892156 (1975-07-01), Johnstone
patent: 4402241 (1983-09-01), Moores, Jr.
patent: 4420996 (1983-12-01), Greding et al.
patent: 4474096 (1984-10-01), Muller
patent: 4540394 (1985-09-01), Cavagna
patent: 5025693 (1991-06-01), Tidland et a
Dax James
Knutson Jeffrey
Piper Marbury Rudnick & Wolfe
Rachuba M.
Valmet Corporation
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