Stock material or miscellaneous articles – All metal or with adjacent metals – Having variation in thickness
Reexamination Certificate
1999-05-21
2001-07-17
Zimmerman, John J. (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Having variation in thickness
C428S687000
Reexamination Certificate
active
06261702
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to embossed rolled steel sheet. More specifically, the invention relates to embossed rolled steel sheet with a surface pattern that replicates an abrasively polished surface along with a method and apparatus for producing the same.
2. Description of the Prior Art
A significant portion of the flat rolled stainless steel sheet used commercially has a polished finish. The finish is generally produced by abrading the surface to produce a sanded appearance. This sanded appearance may also be produced by embossing on the steel sheet a similar pattern. While embossing generally provides the visual equivalent of the abraded surface, a relatively small percentage of steel sheet is processed in this fashion to produce such a surface.
However, abrasive finishing is costly and time-consuming and may produce an inconsistent surface that is prone to defects, such as polishing chatter, pits, and abrasive belt marks.
FIG. 1
illustrates a section of steel sheet
10
having a surface
15
with a sanded appearance. The surface
15
includes a multiplicity of slits
20
oriented about a longitudinal axis
25
generally in a random fashion.
As seen in
FIG. 2
, the slits (not shown) on the surface
15
of the sheet
10
are produced by moving the sheet
10
in a direction
30
from a payoff reel
32
past an abrasive roller
35
which has abrasive tape
40
about the periphery of the roller
35
to a take-up reel
37
. A relatively rigid roller
45
opposes the roller
35
, thereby permitting the abrasive tape
40
of the roller
35
to be applied against the sheet
10
with a predetermined pressure. Furthermore, the roller
35
rotates as indicated by arrow
47
against the direction
30
of travel of the sheet
10
by a motor
50
and a connecting belt
55
.
The surface
15
of the sheet
10
contacts the roller
35
only tangentially such that rotation of the roller
35
against the surface
15
produces the short slits
20
found in FIG.
1
. In general, the length of these slits along the longitudinal axis
25
is between 5 to 10 millimeters and these slits are unevenly spaced since they correspond with the locations of the individual pieces of grit on the abrasive tape
40
.
While this surface finish is aesthetically pleasing, in the event a portion of the surface becomes damaged, once repaired the sanded appearance must be reproduced. It is extremely difficult to reproduce this appearance because of the randomly spaced longitudinal slots
20
and it is equally difficult to provide a seamless transition between the repaired surface and the original surface. For that reason, a different type of surface finish was sought that would be more amenable to being repaired.
FIG. 3
illustrates a portion of a steel sheet
110
having a surface
115
with a plurality of grooves
120
extending parallel to a longitudinal axis
125
.
As illustrated in
FIG. 4
, the grooves
120
in the surface
115
of the sheet
110
are produced by moving the sheet
110
in the direction of arrow
130
from a payoff reel
132
between an element
135
having an abrasive surface
140
and a rigid roller
145
opposing the element
135
to a take-up reel
147
. The abrasive surface
140
extends across the entire width of the sheet
110
such that when the sheet
110
is moved in the direction
130
, the plurality of grooves
120
is produced over the surface
115
of the sheet
110
.
This surface finish is more amenable to being repaired; however, as previously mentioned, abrasive finishing is costly and time-consuming and may produce an inconsistent surface with defects. As an example,
FIG. 5
, which is an optical microscopy image of a steel sheet of stainless steel type
304
having an AISI number
3
polished finish to give the appearance of a brushed finish, illustrates typical surface tears and pits, not uncommon when abrasive polishing is used.
Steel sheet surfaces with these defects have associated disadvantages. First of all, the exposed steel sheet with surface tears and pits is more prone to corrosion than a surface without these. Furthermore, polished steel sheet is used on equipment in contact with food, chemicals and pharmaceuticals because of its resistance to corrosion and oxidation. It is important for the surface finish to be aesthetically pleasing, cleanable and resistant to corrosion. The cleanability of the sheet is significantly reduced by the introduction of such defects. Furthermore, as highlighted in the discussion of
FIG. 4
, the abrasive surface
140
is urged against the surface
115
of the sheet
110
and therefore a typical abrasive element
135
must be replaced approximately every 5,000 feet of surface that is abraded. Finally, the speed at which the sheet
110
travels past the abrasive element
140
is generally approximately 50 feet per minute. This produces a bottleneck since, for the most part, all of the other processes associated with finishing the sheet run at much higher speeds.
For that reason, a sheet is desired with a surface pattern that provides the same relative ease of repair to damage on the brushed surface but does not have the disadvantages associated with the damage caused by abrasion, relatively short life of the abrasive element and relatively slow speed associated with the abrasion process.
BRIEF SUMMARY OF THE INVENTION
One embodiment of the invention is an embossed steel sheet having a longitudinal axis comprising a plurality of straight grooves in the steel sheet which are continuous and parallel to one another defining an embossed pattern of straight grooves along a groove axis with each groove having associated with it one valley and two peaks. Each groove also has a wall connecting the peak of the groove to the valley of the groove with the vertical distance between the peak and valley of the groove defining the depth of the groove.
In a second embodiment of the invention, a steel sheet is embossed with a pattern using a method comprising the steps of providing a steel sheet having a sheet longitudinal axis and embossing the steel sheet by rolling the steel sheet with a working roll having a plurality of straight channels in the roll periphery along a channel axis which are continuous and parallel to one another defining an embossing pattern of straight channels along the channel axis. Each groove also has a wall connecting the peak of the channel to the valley of the channel with the vertical distance between the peak and valley of the channel defining the depth of the channel.
A third embodiment of the invention is a method of making an embossed steel sheet having surface characteristics optimized to improve repairability, corrosion resistance and cleanability of the sheet surface, the method comprising the steps of providing a steel sheet having a sheet longitudinal axis and embossing the steel sheet by rolling it using a textured working roll so that the resulting embossed steel sheet has a plurality of straight grooves which are continuous and parallel to one another defining an embossed pattern of straight grooves along a groove axis. Each groove also has a wall connecting the peak of the groove to the valley of the groove with the vertical distance between the peak and valley of the groove defining the depth of the groove.
A fourth embodiment of the invention is a roll on a temper mill used to emboss a surface pattern onto steel sheet, wherein the roll has a roll longitudinal axis and a roll radial axis and wherein the surface of the roll is comprised of a plurality of straight channels along the roll periphery which are continuous and parallel to one another defining a roll surface pattern, and wherein each channel also has a wall connecting the peak of the channel to the valley of the channel with the vertical distance between the peak and valley of the channel defining the depth of the channel.
A fifth embodiment of the invention is a method for fabricating a roll on a working mill used to emboss a surface pattern onto steel sheet comprising the steps of rotating the roll
McGuire Michael F.
Perkins Timm F.
Senzarin-Kulik Kelly L.
J&L Specialty Steel, Inc.
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
Zimmerman John J.
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