Cutting – Processes – Cut advances across work surface
Reexamination Certificate
1998-11-19
2001-10-30
Rada, Rinaldi I. (Department: 3724)
Cutting
Processes
Cut advances across work surface
C083S501000, C083S582000, C083S698310, C083S698410
Reexamination Certificate
active
06308601
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to the field of slitting of materials. More particularly, the invention concerns an apparatus and method for slitting thin sheets of media, such as photographic paper and film, with cooperating blade members capable of engaging movements under uniform contact force thereby improving the quality of the finished media and prolonged usefulness of the slitter elements.
BACKGROUND OF THE INVENTION
Conventional slitting devices used for slitting thin media, such as photographic paper and film, employ some sort of biasing member to control the contact force between cooperating blades or knife members. Typically such media is mass produced in large width master coils and then is cut to narrow width coils from the master coil using such slitting knives. Skilled artisans will appreciate that contact force is the force that one blade member exerts upon the other during a cutting operation.
Some success has been achieved in the art with a variety of biasing members, typically springs, presently used for biasing slitter blade members in an attempt to control the contact force between contacting blades. As shown in prior art
FIGS. 1 and 2
, the contact force between existing displaceable and stationary slitter knives or blade members
10
,
12
is typically created by using a spring system
14
behind the displaceable blade member or knife
10
. Various types of springs are currently in use, including coil
16
(illustrated in FIG.
3
A), Belleville™
18
(illustrated in FIG.
4
A), and garter
20
(illustrated in FIG.
5
A). In each of these prior art devices, knives or blades
10
,
12
, are attached to a knife or blade carrier
22
via some sort of attachment, such as a retainer ring
24
(
FIGS. 4A
,
5
A,), or screws
26
(FIGS.
1
-
3
A). Despite the progress accomplished with the above biasing members, a major shortcoming associated with each of these various biasing springs is that they create uneven spring forces around the circumference of the knife or blade member, as depicted in
FIGS. 3B
,
4
B, and
5
B. Experienced artisans will appreciate that these variations in spring force adversely affect the wear of the slitter knives as well as the quality of the slit edge.
Therefore, there persists a need in the art for a slitter element useable in an apparatus for slitting thin media, such as photographic paper and film, that provides uniform media slitting resulting from a uniform contact force between cooperating engaging blade members of the slitting device.
SUMMARY OF THE INVENTION
It is, therefore, an object of the invention to provide a slitter wherein cooperating blade members exert a uniform force widthwise across the blades when the blades are in engaging contact.
It is another object of the invention that an apparatus for slitting a web material uses an elastomeric biasing member for producing uniform engaging movements of the axially moveable blade
It is yet another object of the invention to provide a elastomeric member in which the contact force between engaging blade members is achieved by fixedly arranging an elastomeric biasing member in a recess of the frame member.
The present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the present invention, apparatus for slitting thin media, such as photographic paper and film comprises a substantially rigid slitter body and a first stationary blade member fixedly arranged in the slitter body. A second, cooperating blade member is arranged in the slitter body for axial engaging movements with the first blade member. In our invention, a uniform contact force between axially engaged second blade member and the first blade member is produced by an elastomeric biasing member fixedly arranged in a recess of the slitter body. The elastomeric biasing member provides continuous and uniform biasing contact with a face of the second blade member particularly when the second blade member is in engaging contact with the first blade member during a slitting operation.
In another aspect of the invention, a method of slitting a sheet of web material, comprises the steps of providing a slitter described above and providing a source of web material to be fed into said slitter. Web from the source is fed into the slitter with the first blade member and the second blade member of the slitter being axially spaced apart to receive the web. The second blade member is displaced for axial engagement with the first blade member thereby producing a slit sheet of web material.
The present invention has numerous advantageous effects over prior art developments. First, when slitting a sheet of web material, the circumferential force-deflection response of the elastomer spring to the engaging movements of the cooperative blade members is linear and more uniform compared with conventional spring designs.
Further, elastomeric slitter knife springs reduce the time required to set up a slitter knife assembly. Compared with conventional spring designs, no shimming, sorting, or other adjustments are required with elastomeric springs.
Also, elastomeric springs may be readily designed to have the desired force-deflection response. In general, elastomer springs appear to have more consistent force-deflection characteristics from spring to spring compared with coil and Belleville springs.
Moreover, elastomeric springs offer more uniform circumferential forces, longer life, elimination of fretting corrosion, and easier knife assembly.
Still further, conventional springs, such as the ones referred to above, are fabricated from metallic materials. During slitting, the motion of the springs relative to the metallic knife and collar causes fretting wear and corrosion. In manufacturing photographic products, the iron-based fretting wear debris generated by these spring materials is unacceptable. Slitter knife assemblies with elastomeric springs do not generate fretting wear debris.
Finally, since elastomers may be molded, the cross-sectional profile of the spring may be controlled to provide the desired force-deflection response. Because of their toughness, corrosion resistance, durability, resistance to compression set, wide range of durometer hardness, and ease of manufacture (e.g. casting or molding), polyurethane elastomers are particularly advantageous for spring applications.
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Budinski Michael K.
Seyna John J.
Bailey, Sr. Clyde E.
Eastman Kodak Company
Goodman Charles
Rada Rinaldi I.
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