U.S. patent number 3,763,030 [Application Number 05/168,062] was granted by the patent office on 1973-10-02 for apparatus for the production of seamless hollow cylinders.
Invention is credited to Peter Zimmer.
United States Patent |
3,763,030 |
Zimmer |
October 2, 1973 |
APPARATUS FOR THE PRODUCTION OF SEAMLESS HOLLOW CYLINDERS
Abstract
The invention relates to a matrix device for making seamless
hollow cylinders for use as cylindrical screen printing stencils. A
cylindrical metal film is electrolytically formed in either
unperforated or a perforated form upon an expandable and
contractible hollow, cylindrical rotary matrix. The metal film is
subsequently removed from the matrix. The cylindrical hollow matrix
consists of a cylindrical jacket disposed between endpieces and is
provided inside, at least in the jacket zone, with a gas or liquid
tight hollow space, accessible by at least one valve. The jacket of
the matrix in one form consists of a cylindrical inner jacket sheet
of rubber elastic material and of a separate cylindrical outer
jacket of electrically conductive metal material. Both the inner
jacket and the outer jacket are concentrically connected to or
between the axially opposed endpieces with the outer jacket and the
inner jacket only in loose contact intermediate the ends thereof. A
valve is provided usually in an end piece through which pressurized
fluid is admitted or allowed to escape, as required. In another
form, only an outer metallic foil like jacket is sealingly attached
in a fluid-tight manner to the endpieces and is of such character
to be slightly expandable while maintaining a smooth outer surface
on which the electrolytically deposited cylinder is formed in an
endless cylindrical manner, and is subsequently capable of being
deflated sufficiently to permit easy removal of the
electro-deposition. Suitable screen patterns can be formed
simultaneously by applying insulated sleeves having predetermined
screen aperture patterns to the metallic foil matrix jacket. The
expandability characteristic enables the formation of relatively
thicker perforated rotary printing screens than have been available
by previously known process and apparatus.
Inventors: |
Zimmer; Peter (Kufstein,
OE) |
Family
ID: |
22609948 |
Appl.
No.: |
05/168,062 |
Filed: |
August 2, 1971 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
697464 |
Jan 12, 1968 |
|
|
|
|
Current U.S.
Class: |
204/281;
101/128.4; 205/73 |
Current CPC
Class: |
C25D
1/02 (20130101) |
Current International
Class: |
C25D
1/00 (20060101); C25D 1/02 (20060101); C23b
007/00 (); C23b 007/02 (); B01k 001/00 () |
Field of
Search: |
;204/11,9,281 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
975,147 |
|
Nov 1964 |
|
GB |
|
8,108 |
|
1892 |
|
GB |
|
Primary Examiner: Tung; T.
Assistant Examiner: Tufariello; T.
Parent Case Text
This application is a continuation-in-part of my copending
application Ser. No. 697,464, filed Jan. 12, 1969, now abandoned.
Claims
What is claimed is:
1. A hollow cylindrical matrix device for use in the electrolytic
production thereon of relatively light weight, thin, metallic
seamless, hollow cylinders to be used in the making of screen
printing stencils and which are individually formed and removed
from the matrix device after formation, said matrix device
comprising, in combination;
a. a pair of axially opposed, spaced apart end pieces;
b. a cylindrical jacket means interposed and operatively connected
with said end pieces, said jacket means and said end pieces forming
a fluid-tight chamber,
c. said jacket means comprising an electrically conductive metallic
sheet having the characteristic of being expansible outwardly in
response to pressure internally of said chamber;
d. said metallic sheet having an inner cylindrical pressure
receiving surface and an outer cylindrical deposit receiving
surface;
e. means operatively connected with said chamber for inserting
pressurized fluid therein to act on said pressure receiving surface
and to expand said metallic sheet;
f. electric insulating means applied to said deposit receiving
surface and providing a predetermined screen-forming pattern for
effecting formation of predetermined screen perforations
simultaneously with the electrolytical formation of said seamless
cylinder.
2. A matrix device as defined in claim 1, wherein said axially
opposed end pieces are of circular form and said metallic sheet is
adjoined in a fluid pressure tight manner to said end pieces near
their outer peripheries.
3. A matrix device as defined in claim 1, wherein said insulating
means includes means to define point-shape openings in the formed
screen stencil, and the ratio between the thickness of said
insulation means and the thickness of an electro-deposition of the
screen being within the range of from 1:1 up to at least 1:4.
4. A hollow cylindrical matrix device for use in the electrolytic
production thereon of relatively light weight, thin, metallic
seamless, hollow cylinders to be used in the making of screen
printing stencils and which are individually formed and removed
from the matrix device after formation, said matrix device
comprising, in combination:
a. a pair of axially opposed, spaced apart end pieces
b. a cylindrical jacket means interposed and operatively connected
with said end pieces, said jacket means and said end pieces forming
a fluid-tight chamber,
c. said jacket means comprising
1. an electrically conductive metallic sheet having the
characteristic of being expansible outwardly in response to
pressure internally of said chamber;
2. an inflatable/deflatable inner jacket having at least one member
of elastic rubber-like material extending between said end pieces
and concentrically underlying and adapted to operatively
expansively engage with said metallic sheet in response to a
predetermined increase of the internal fluid pressure,
d. said metallic sheet having an inner cylindrical pressure
receiving surface and an outer cylindrical deposit receiving
surface and said elastic member having an outer cylindrical
pressure applying surface engageable with said pressure receiving
surface;
e. means operatively connected with said chamber for inserting
pressurized fluid therein to cause said pressure applying surface
to act on said pressure receiving surface and to expand said
metallic sheet;
f. electric insulating means applied to said deposit receiving
surface and providing a predetermined screen-forming pattern for
effecting formation of predetermined screen perforations
simultaneously with the electrolytical formation of said seamless
cylinder.
5. A matrix device as defined in claim 4, wherein said insulating
means includes means to define point-shape openings in the formed
screen stencil, and the ratio between the thickness of said
insulation means and the thickness of an electro-deposition of the
screen being within the range of from 1:1 up to at least 1:4.
6. A matrix device as claimed in claim 4, wherein said
inflatable/deflatable inner jacket comprises an annular tubular
member concentrically underlying said metallic sheet, and said
means to insert pressurized fluid is connected to the interior of
said tubular member.
Description
THis invention relates to a device for the production of jointless
hollow thin metallic cylinders of both the non-perforated and
perforated type, some of which are useable for cylindrical screen
printing stencils wherein a cylindrical and sometimes perforated
metal film is electrolytically formed upon a hollow cylindrical
matrix, and whereby said metallic film is subsequently readily
removed from the matrix.
The production of jointless cylindrical metal bodies by means of an
electrolytic process is known, as is the removal of the
electrodeposition from the electrode core or from the matrix,
according to known methods, in such a way that the periphery of the
deposited metal shell is stretched by the action of pressure
rollers. Furthermore, the use of an electrode core or a matrix of
an easily fusable material which it is melted out after the
galvanization is known. Furthermore, it has been proposed to
chemically separate the matrix material from the
electro-deposition. Another known process consists in that a
cylindrical metallic film is electrolytically formed on a
cylindrical metal matrix whose material has a coefficient of
thermal expansion different from that of the matrix material,
whereafter the hollow cylindrical metal film is removed from the
matrix by subjecting them to a change of temperature.
In all of these known methods, the removal of the
electro-deposition is not achieved in a fully satisfactory way
because the matrix is often destroyed or because a sufficient
difference between the external diameter of the matrix and the
internal diameter of the electro-deposition cannot be practically
attained, or such involves impractical difficulties.
This foregoing disadvantage is eliminated according to the present
invention in that an improved matrix is formed of a cylindrical
hollow body which can be at least partially filled with a fluid
pressure medium, and whose jacket consists of an elastic,
electrically conductive material, said jacket being expanded by an
increased internal pressure applied within the cylindrical hollow
body while the thin metal film is electrolytically deposited
thereon, and whereafter the electrolytically deposited metal film
is drawn off as a jointless hollow cylinder after the increased
internal pressure has been reduced and the elastic jacket has
substantially returned to its initial form.
As mentioned above, many of the hollow cylinders produced by the
improved apparatus of and according to the process of this
invention are preferably used as cylindrical screen printing
stencils and must be provided with perforations for this purpose.
After the electrolytic production of such a hollow cylinder having
a solid uninterrupted wall, perforations can be made by an etching
operation. However, it is also possible to simultaneously
electrolytically deposit a hollow cylinder and form the desired
perforations on the matrix. In this latter case an insulating layer
with a predetermined pattern for forming open spaces is applied on
the matrix, whereby no electro-deposition is formed on the
insulated areas so that the electrolytically produced hollow
cylinder is provided with perforations in these areas. The pattern
or perforations and thus the insulating cover useable on the matrix
can be of any of a variety of different predetermined patterns. A
main advantage of the process attendant using the improved
apparatus resides in the galvano-plastic production of such
perforated hollow cylinders which permits the application of a
relatively thick insulating layer of a desired point pattern. This
implies that the electro-deposition only fills the spaces between
the insulating points or areas, without being deposited on the
surface of the insulated areas at their circumference, or deposited
thereon only to a very minor extent.
Heretofore it has only been possible to apply insulating layers or
insulating points having a relatively small thickness to the
conductive surface of the matrix because it was impossible to
withdraw the electrolytically deposited hollow cylinder from such a
matrix having relatively thickly insulated elevations on the
matrix. By use of the improved matrix apparatus and attendant
process according to this invention, insulating layers or
insulating points having a relatively and significantly greater
thickness are now possible because the outer diameter of the matrix
can be considerably decreased by the reduction of its internal
pressure. This enables a hollow cylinder, such as a screen printing
stencil, to be produced, which much more precisely corresponds to
the insulated pattern on the surface of the matrix with regard to
the perforations. Furthermore, such an improved formed printing
stencil also permits the formation of color runs and halftones.
Where multicolor printing is being done, it is important to be able
to produce a plurality of screen cylinders having accurately
uniform outer diameters, as by the use of the matrix device of this
invention, whereby one master matrix can be used for the production
of the needed plurality. The master matrix device hereof serves as
the cathode during the electroplating process as it is rotated
between the anodes in the galvanic vat.
One form of appropriate apparatus for effecting the process hereof
essentially consists in that the cylindrical matrix is provided
internally, at least in the peripheral jacket zone, with a gas or
liquid-tight hollow space, accessible by at least one valve,
preferably in an end disc, and in that at least an external jacket
is made of a semi-resilient or partially expandible electrically
conductive material. It is also convenient but not absolutely
necessary to provide an internal jacked formed of rubber or other
elastic-like material concentrically adjacent to said electrically
conductive, external jacket. The internal jacket is such as to seal
or form a gas- or liquid-tight internal hollow space. The internal
jacket is preferably joined to the opposite end walls of the matrix
in a suitable gas- or liquid-tight way.
Where an internal jacket is not used, it is possible to essentially
achieve the same effect to a large degree by attaching a
longitudinally seamless external jacket at its ends in a
fluid-tight manner to the opposite disc shaped end plates of the
matrix device.
The present novel use of an expandable external jacket formed of a
thin metallic foil such as nickel foil and having a smooth outer
peripheral surface assures the ability to electrolytically form
thereon a metallic cylinder or perforated cylindrical printing
screen having a more uniform thickness and smoothness throughout as
well as more distinctive and uniformly formed perforations in the
case of rotary printing screen stencils. Cylindrical screens of
greater thickness are also available, due to the improved apparatus
and the use thereof. This is a marked improvement over the known
prior art devices which have been known to use much less effective
expandable mandrels or matrixes utilizing rubber or rubber-like
outer jacket means which are more susceptible to irregular wear and
non-uniform expansion. The use of a rubber jacket, whether coated
or not, is adversely subject to irregular tensions and where
thinner, less uniformly formed areas of the rubber wall occur, the
rubber jacket is susceptible to higher tensions and bulging,
thereby detracting from the ability to produce precisely and
uniformly formed electrolytically deposited cylinders thereon.
Also when a rubber-like jacket is covered with an electrically
conductive coating, such coating tends to become brittle and
fractured by being subjected to continuous expansion and release,
thereby not having the ability to produce the desired degree of
uniform and smooth electro-deposited cylinders thereon.
In applicant's proposed apparatus, the use of thin nickel foil
plating in a seamless manner as the expandible outer jacket enables
it to be inflated and deflated to the necessary extent to permit
removal of the electrolytically formed cylinder without the need
for the application of chemicals often otherwise used in the prior
art and which nickel material cannot withstand.
Furthermore, weight and expense considerations are important
factors to be considered, and the control of the outer
circumference or peripheral surface of a rotary printing screen is
very important to the various printing arts. The previously known
solid heavy cylinders often made of nickel or other material were
very expensive and very heavy. For example, a cylinder of a given
size made of the more solid heavy nickel could weigh between 500 to
1,000 pounds, as compared to approximately 10 pounds or so for the
light-weight metallic foil matrix of the present invention
embodying the light-weight nickel foil-like outer jacket. It is
apparent that the relative costs would also be diminished for the
light-weight apparatus, being only approximately one-tenth the cost
of the heavier device, for example $200.00 compared to about
$2,000.00. Also, in the use of the heavy solid type device, much
grinding and polishing is required to obtain an accurate surface,
and such rigid devices more subject to defacement by scratching,
etc., during stripping or other handling thereof. In comparison to
applicant's improved light-weight matrix, due to the relative
resiliency of the outer (and inner) jacket, it was not as easily
defaced or scratched, and lends itself to the required degree of
flexibility to expand and contract or be deflatably compressed to
enable easy removal of the electro-deposited cylinders therefrom.
Applicant's device assures a more efficient working screen cylinder
formed thereon, such as a ductile nickel screen, having the ability
to produce sharper and more distinctive copy therefrom and without
having any longitudinal seam.
It is also to be noted that the problem of removing an
electro-deposited cylinder after its formation is totally different
and unrelated to those devices which serve merely as a support to
receive thereon previously formed cylinders which are to be
subjected to subsequent fabrication treatment. The light-weight
matrix formed according to this invention is not intended to
withstand the strain of attempted removal of electro-deposited
cylinders by the usual means apart from deflating methods. Also,
the heavy-weight type and light-weight types are much different
with respect to the degree of relative firmness and their
respective ability to withstand buoyant forces in a galvanic vat or
chamber, and care must be taken not to apply to subject the
light-weight foil-type matrix to such excessive forces, whether
attendant the phase of inflating or expanding the matrix jacket or
whether subjecting the matrix to the buoyant forces, which forces
may cause it to rupture with attendant danger to the operational
work crew. In this regard, heretofore it was not thought possible
to be able to evolve a light-weight matrix of this character for
such successful use in galvanic deposition forming of thin
cylinders for use as printing screens and the like. As an example,
in the fabrication of large carpet printing screens having
approximately a 300 mm diameter, a 1,000 mm circumference and a
length of about 5-6 m, the fluid expandable matrix jacket is a
metal sheet or foil of only a few 10 th mm wall thickness which is
stretched between the end mounting plates. In operation the fluid
or air-filled matrix is fixedly mounted for axial rotation at its
end plates while submerged or at least partially submerged in the
galvanic vat, the buoyant forces in such a situation exert a
pressure of about 500 kg on the thin jacket imparting shear forces
with respect to the longitudinal axis tending to bend or otherwise
break or deform it. For safety reasons, an internal expandable
pressure of the matrix jacket is limited to less than 1 kg per sq.
centimeter. Of course, the dimensions of the matrix may vary for
different uses, and may be proportionately smaller including, for
example, a size of about 200 mm diameter with a length of from 2.5
to 3 m.
Embodiments of the invention are hereinafter described with
reference to the accompanying drawings without being limited
thereto.
FIGS. 1-4 are schematic views of a device according to the present
invention showing different states of its use;
FIGS. 5 and 6 correspond to FIGS. 1 and 2, but depict a modified
embodiment;
FIG. 7 is a further modification; and
FIGS. 8 and 9 are fragmentary enlarged cross-sections of the
electro-deposition.
Referring to FIGS. 1-4, the matrix consists of a carrier shaft 1 on
which opposite end disks 2 are attached to rotate with the latter.
Spanning the two end disks 2 is a rubber jacket 3 and an
electrically conductive jacket 4 of a metallic-like foil, such as
nickel foil, is spanned over the latter. The thickness of the
metallic jacket may vary for different applications and range from
0.13 to 0.3 mm, and in some special cases, to 0.6 mm. The inside of
the matrix is an outwardly sealed fluid-tight hollow space,
accessible by at least one valve 6 to facilitate inflation and
deflation thereof.
The inside hollow space which receives the gas or liquid pressure
medium need not extend over the whole inside space of the matrix.
For example, as distinct from the FIGS. 1-4, a circular or
ring-line in cross-section gas or liquid-tight hollow space lying
in the jacket zone which receives the pressure medium for the
expansion of the external jacket of the matrix would be
sufficient.
FIG. 1 illustrates a state in which the internal pressure in the
hollow space is equal to the external pressure. Upon pneumatic or
hydraulic increase of the internal pressure, the rubber jacket 3
and thus the conductive jacket 4 is extended, as illustrated in
FIG. 2. As can be seen from FIG. 3, an electro-deposition in the
form of a seamless cylindrical metal film 8 is deposited, while
within a galvanic vat, with the matrix rotating relative to the
anodes 7. Upon completion of the deposited film 8, the internal
pressure in the inside hollow space of the matrix is again reduced.
Thus, the elastic, electrically conductive jacket is deflatable and
at least partially substantially returns to its initial diameter.
The electrolytically deposited cylindrical metal film 8, however,
is not elastically stressed and maintains its diameter as formed.
Thus the cylindrical metal film 8 is loosened and can easily be
drawn off from the matrix (FIG. 4). The thickness of the deposited
metallic foil-like cylinders may vary within an approximate range
of from 0.04 to 0.25 mm, and after formed have a rigidity
resembling fine razor blades.
FIGS. 5 and 6 are similar to FIGS. 1 and 2, respectively, and
depict the form of the matrix which omits the inner rubber jacket
3. In this embodiment, where there is no inner jacket used to help
provide back-up support, it may be desirable to utilize a somewhat
heavier gauge metallic outer jacket while still retaining the
semi-resilient or expandable characteristic thereof.
FIG. 7 is a view similar to FIG. 4, but depicting a modified form
of the inner jacket 3' which is of annular tubular form, and valve
6' is operatively connected thereto through the end disc 2.
FIGS. 8 and 9 illustrate the particular advantage of the present
invention in the galvano-plastic production of perforated hollow
cylinders. In order to electrolytically produce a perforated hollow
cylinder, an insulating cover 9 having preferably point-shaped
openings must be applied around the electrically conductive jacket
4 of the matrix. Said cover means may consist, e.g., of
photosensitive lacquer and be advantageously produced by means of
the photostatic method. As generally known, during this process the
conductive jacket 4 of the matrix is provided with a layer of
photosensitive lacquer which has not yet been exposed and whose
diameter is uniform. After drying of this layer, a suitable film is
applied onto said photosensitive lacquer, said film then being
exposed and developed. After development the body of the cover
means 9 remain while the spaces defined by the cover means show the
bright metallic exposed surface of the conductive jacket 4 of the
matrix. If these insulating cover means 9 are considerably smaller
in wall thickness than the wall thickness of the perforated hollow
cylinders 8 to be produced, then the electro-deposition forming the
perforated hollow cylinders 8 tends to overlay in such a manner
that the spaces in the cover means 9 become more filled until the
thickness of the electro-deposition reaches the thickness of the
insulation cover means 9. Upon continuing deposition of the
preferably nickel material, this deposition outwardly builds and
overlays the insulation cover means 9 and the perforations formed
during the electro-deposition of the hollow cylinders 8 becomes
smaller the more the wall thickness of the cylinders 8
increases.
In some known processes in which a cover means 9 having a thickness
of only approximately 0.01 mm could be used, and where the
electrolytically deposited hollow cylinders 8 built-up a wall
thickness of approximately 0.08 mm, the extent of the decrease of
the perforation size is especially high. According to the present
of the invention, considerably thicker insulating cover means 9 are
possible, up to the thickness of the electro-deposit of the hollow
cylinder 8, and perhaps even more.
As can be seen from FIG. 9, the electro-deposit does not, or does
only to a very small extent, overlay on the insulating cover means
9, if the thickness of these cover means is not substantially kept
below the thickness of the electro-deposit, so that the
perforations of the formed hollow cylinder 8 practically equal
those in size of the cover 9. The larger the diameter of the
insulating covers 9 in comparison to the diameter of the galvanic
metal film of the hollow cylinder 8 to be produced, the more
accurately the perforations correspond to the matrix pattern.
While the ratio of the mentioned thicknesses (photosensitive
lacquer:electro-deposit) previously has been 1 : 10 to 1 : 8 at the
most, the ratio of the thickness (insulating cover or
photosensitive lacquer:galvanic metal film) can now be 1 : 4,
preferably more than 1 : 2, up to 1 : 1, by this invention.
* * * * *