U.S. patent number 3,733,709 [Application Number 05/140,760] was granted by the patent office on 1973-05-22 for reflector and cooling means therefor.
This patent grant is currently assigned to Sun Chemical Corporation. Invention is credited to Robert W. Bassemir, Julius Robert Mayer.
United States Patent |
3,733,709 |
Bassemir , et al. |
May 22, 1973 |
REFLECTOR AND COOLING MEANS THEREFOR
Abstract
Printing apparatus utilizing lamps generating ultraviolet light
to cure solvent-free ink by photopolymerization is provided with
lamp reflectors having shutters to permit the lamps to remain
energized while the printed work conveyor is stopped or is moving
at a slow rate. A plurality of such lamps, each with an individual
shutter, are arranged in parallel rows extending transverse to
direction of movement of the work. As the shutters are closed, lamp
voltage is reduced to a standby point where the lamps remain fired.
Air is circulated at the same time behind the lamp reflector for
cooling of the latter without appreciably cooling the lamp. Each
reflector is a sheet of non-oxidizing metal mounted in the concave
portion of a structurally strong housing. End reflectors prevent
end scattering of the lamp-radiated energy and shield the lamp
sockets from the heating effects of this energy. The lamp sockets
are repositionable with respect to the reflector so that the arc
thereof may be positioned generally along the focus line of the
reflector for different positions of the focus line with respect to
earth.
Inventors: |
Bassemir; Robert W. (Jamaica,
NY), Mayer; Julius Robert (Waldwick, NJ) |
Assignee: |
Sun Chemical Corporation (New
York, NY)
|
Family
ID: |
22492690 |
Appl.
No.: |
05/140,760 |
Filed: |
May 6, 1971 |
Current U.S.
Class: |
34/277;
250/505.1; 432/230; 250/504R; 392/421; 432/233 |
Current CPC
Class: |
B41F
23/04 (20130101) |
Current International
Class: |
B41F
23/00 (20060101); B41F 23/04 (20060101); F26b
003/28 () |
Field of
Search: |
;263/8 ;34/1,4,7,49 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Sprague; Kenneth W.
Claims
The embodiments of the invention in which an exclusive privilege or
property is claimed are defined as follows.
1. Apparatus including curing means for solvent-free coating and
printing material, said curing means including radiant energy
means, and conveyor means for moving work to which said material is
applied along a feed path in front of said radiant energy means,
whereby radiation therefrom impinges on said work and cures the
material thereon; said radiant energy means comprising a plurality
of sections each including an ultraviolet-producing lamp and a
reflector means to direct radiation from said lamp toward said feed
path and cooling means for generating air flow along said reflector
means to cool the latter without appreciably cooling said lamp.
2. Apparatus including curing means for solvent-free coating and
printing material, said curing means including radiant energy
means, and conveyor means for moving work to which said material is
applied along a feed path in front of said radiant energy means,
whereby radiation therefrom impinges on said work and cures the
material thereon; said radiant energy means comprising a plurality
of sections each including a lamp; a reflector means to direct
radiation from said lamp toward said feed path; cooling means for
generating air flow along said reflector means to cool the latter
without appreciably cooling said lamp; and a shutter means operable
to a closed position to block radiation from reaching said feed
path, operating means to open and close said shutter means, second
control means to automatically coordinate operation of said cooling
means and said shutter means, whereby upon closing of said shutter
means said air flow is increased.
3. Apparatus including curing means for solvent-free coating and
printing material, said curing means including radiant energy
means, and conveyor means for moving work to which said material is
applied along a feed path in front of said radiant energy means,
whereby radiation therefrom impinges on said work and cures the
material thereon; said radiant energy means comprising a plurality
of sections each including a lamp and a reflector means to direct
radiation from said lamp toward said feed path and cooling means
for generating air flow along said reflector means to cool the
latter without appreciably cooling said lamp, said reflector means
including an elongated housing and an elongated reflector sheet
secured thereto in a manner to permit relative movement
therebetween thereby accommodating for differential expansions;
said housing being constructed to direct said air flow.
4. Apparatus as set forth in claim 3 in which the housing is
constructed of much stronger material than said reflector
sheet.
5. Apparatus as set forth in claim 4 in which the reflector sheet
is constructed of material having generally the oxidation-resisting
and reflecting properties of Lurium.
6. Apparatus including curing means for solvent-free coating and
printing material, said curing means including radiant energy
means, and conveyor means for moving work to which said material is
applied along a feed path in front of said radiant energy means,
whereby radiation therefrom impinges on said work and cures the
material thereon; said radiant energy means comprising a plurality
of sections each including a lamp and a reflector means to direct
radiation from said lamp toward said feed path and cooling means
for generating air flow along said reflector means to cool the
latter without appreciably cooling said lamp, said lamp including
an elongated envelope; and additional reflectors at each end of
said reflector means to reduce end spill of radiation from said
lamp and to shield the ends of said envelope from excessive heating
by lamp-produced radiation.
7. Apparatus including curing means for solvent-free coating and
printing material, said curing means including radiant energy
means, and conveyor means for moving work to which said material is
applied along a feed path in front of said radiant energy means,
whereby radiation therefrom impinges on said work and cures the
material thereon; said radiant energy means comprising a plurality
of sections each including a lamp and a reflector means to direct
radiation from said lamp toward said feed path and cooling means
for generating air flow along said reflector means to cool the
latter without appreciably cooling said lamp, said lamp including
an elongated envelope; sockets removably mounting said lamp and
positioned at opposite ends thereof; and means repositionably
mounting said sockets relative to said reflector means so that an
electric current arc in said envelope is properly positioned with
respect to said reflector means for different positions thereof
relative to earth.
8. Apparatus as set forth in claim 7 in which the reflector means
includes an elongated housing constructed to direct said air flow;
said sockets being secured to said housing; additional reflectors
at each end of said envelope to reduce end spill of radiation from
said lamp and to shield said sockets from excessive heating by lamp
produced radiation.
9. Apparatus as set forth in claim 8 in which the additional
reflectors cooperate with portions of said housing to define
chambers wherein said sockets are disposed; said air flow being
through said chambers to cool said sockets.
10. Apparatus including curing means for solvent-free coating and
printing material, said curing means including radiant energy
means, and conveyor means for moving work to which said material is
applied along a feed path in front of said radiant energy means,
whereby radiation therefrom impinges on said work and cures the
material thereon; said radiant energy means comprising a plurality
of sections each including a lamp and a reflector means to direct
radiation from said lamp toward said feed path and cooling means
for generating air flow along said reflector means to cool the
latter without appreciably cooling said lamp, said reflector means
including an elongated housing and an elongated concave reflector
sheet secured to said housing; said housing having a plurality of
inlet openings positioned adjacent the long edges of said reflector
sheet to facilitate clearing ozone from the area inside said
reflector sheet.
11. Apparatus including curing means for solvent-free coating and
printing material, said curing means including radiant energy
means, and conveyor means for moving work to which said material is
applied along a feed path in front of said radiant energy means,
whereby radiation therefrom impinges on said work and cures the
material thereon; said radiant energy means comprising a plurality
of sections each including a lamp and a reflector means to direct
radiation from said lamp toward said feed path and cooling means
for generating air flow along said reflector means to cool the
latter without appreciably cooling said lamp, said reflector means
being an elongated hood-like member of elliptical cross-section.
Description
This invention relates to printing apparatus in general, and more
particularly relates to means for curing solvent-free inks, and is
an improvement over the apparatus disclosed in U. S. Pat. No.
3,159,464 issued Dec. 1, 1964, to H. C. Early et al. for a Method
of Drying Printed Webs.
Solvent-free inks and other solvent-free coatings are finding
increased utilization in industry, particularly in view of the fact
that use of such materials greatly lowers or completely eliminates
air pollution of the type that results from the curing of solvent
bearing inks and coatings. High speed curing of solvent-free
materials is accomplished by utilizing high power ultraviolet
radiation which is directed at the material immediately after
application thereof.
In accordance with the instant invention, in printing apparatus
ultraviolet radiation is produced by a plurality of parallel
elongated tubes extending transverse to the direction of movement
of the printed material. Associated with each lamp is an elliptical
reflector means for concentrating the ultraviolet radiation in
narrow bands impinging upon the printed material as the latter
leaves the printing station of the apparatus. The reflector sheet
is force-cooled by air circulation primarily at the rear of the
reflector. Since excessive cooling on the lamp side of the
reflector would cause the lamp to cool excessively and extinguish,
air circulation is, for the most part, directed through a housing
to which the reflector sheet is mounted.
Shutter means are operable to a closed position to block light from
impinging upon the printed material without the necessity of
extinguishing the lamp. Operation of the shutter means is
coordinated with speed of travel of the printed material past the
lamps, with a decrease of speed automatically being accompanied by
a decrease in the amount of ultraviolet light impinging
instantaneously on the printed matter, such automatic control being
accomplished by closing the shutters for the required number of
lamps. Since the refiring time for the lamps in question is usually
in the neighborhood of ten to twelve minutes, in order to conserve
press time the lamps should not be extinguished. Thus, in order to
prevent excessive heating of the reflector when its shutter is
closed, the lamp is operated at reduced or standby power, with
firing maintained, and at this time increased air circulation is
applied for cooling of the reflector.
End reflectors prevent end spill of lamp radiation and shield the
lamp sockets from excess heating. The sockets are repositionable on
the housing so that the lamp arc, which tends to rise, will lie
generally on the focus line of the reflector for each position of
the reflector relative to ground.
The reflector sheet is constructed of a metal, such as Lurium or
Alzak, that retains its reflecting properties by being highly
resistive to oxidation even in an oxidizing atmosphere at elevated
temperature and in the presence of ultraviolet radiation.
Accordingly, a primary object of the instant invention is to
provide improved photopolymerization means to cure solvent-free
inks and coatings.
Another object is to provide novel means for cooling of a lamp
reflector without appreciably cooling the lamp.
Still another object is to provide improved coordinated operation
between a lamp, cooling means for the lamp reflector, and shutter
means to selectively block energy from the reflector.
A further object is to provide a novel construction for a housing
which carries a reflecting sheet for an elongated tubular lamp.
These objects as well as other objects of this invention will
become readily apparent after reading the following description of
the accompanying drawings, in which:
FIG. 1 is a schematic illustrating a portion of printing apparatus
constructed in accordance with teachings of the instant
invention.
FIG. 2 is a perspective of a lamp reflector assembly for the
apparatus of FIG. 1.
FIGS. 3 and 4 are end views of the lamp reflector assembly, looking
from left to right, with respect to FIG. 2. In FIG. 3 the
reflector-shutter is opened and in FIG. 4 the shutter is
closed.
FIG. 5 is an elevation showing a fragment of the reflector sheet
and its loose connection to the reflector housing.
FIG. 6 is a cross-section taken through line 6--6 of FIG. 5,
looking in the direction of arrows 6--6.
Now referring to the figures. Printing apparatus 10, illustrated
schematically in FIG. 1, includes feed chain 11 driven in the
direction of arrow A by feed sprocket 12 and guided by idler 13 and
additional idlers (not shown). A plurality of releasable grippers
14 carried by feed chain 11 hold individual sheets 15 for
conveyance by chain 11 along a feed path that extends between
pressure cylinder 17 and print cylinder 18.
After printing is applied to sheets 15, they pass over water-cooled
plate 21, being spaced thereabove by approximately 1 inch. While
sheets 15 pass over cooling plate 21, they pass beneath radiant
energy source lamp-reflector assemblies 26-29 to cure by
photopolymerization the solvent-free ink applied to sheets 15 by
print cylinder 18. As will hereinafter be seen, each assembly 26-29
causes a high intensity radiant image to be formed on work surface
or feed path traveled by sheets 15. Since each of the assemblies
26-29 is identical, only the essential details of assembly 26 will
be hereinafter described by particular reference to FIGS. 2-5.
Assembly 26 includes elongated tubular ultraviolet-producing lamp
31 and stationary hood-like elliptical reflector sheet 32
positioned to the rear of lamp 31 to focus energy near peak
intensity from lamp 31, so that such energy is concentrated over a
short distance along the feed path for chain 11 and housing 36 to
the rear of reflector sheet 32 provides a support for sheet 32 and
lamp sockets 37. Reflector extensions 33, 34 are hinged to housing
36 along the lower edges of concave bottom wall section 36a and
constitute a shutter means operable between the open position of
FIG. 3 and the closed position of FIG. 4. Typically, lamp 31 is a
quartz, medium pressure, mercury discharge tube, in the power range
of 50 to 400 watts per inch.
Housing 36 is constructed of structurally strong metal, whereas
reflector 32 is of relatively thin stock, typically 0.005 inch to
0.150 inch thick. Preferably, the latter is constructed of a
lightweight metal that retains reflective properties by resisting
oxidation even in an oxidizing atmosphere accompanied by heat and
ultraviolet radiation. Suitable metals are sold under the
trademarks Lurium and Alzak. Reflector 32 is mounted to concave
housing wall 36 a by a plurality of screws 88 (FIGS. 5 and 6) that
pass through longitudinally extending slots 87 in reflector 32.
This type of mounting permits reflector 32 to expand and contract
independently of housing 36 when temperature differentials are
present. Relative movement between reflector 32 and housing wall
36a is also facilitated by having the threaded body of screw 88 of
a diameter substantially less than the width of slot 87.
Housing 36 is shaped to provide a conduit to guide flow of cooling
air over the rear surface of housing wall 36a which is in contact,
or heat conducting relationship, with reflector sheet 32. In
particular, lamp tube 31 is positioned at the focus of elliptical
reflector 32, which extends along the full length of lamp 31.
In a manner well known to the art, electrical connections to lamp
31 are made through cap-type sockets 37 at opposite ends of lamp
31, with such sockets being mechanically supported at opposite ends
of housing 36 on end walls 36b, 36c thereof. Additional holes 89 in
walls 36b, 36c are provided for repositioning of sockets 37,
depending upon the orientation of assembly 26 with respect to earth
in that the arc in lamp 31 tends to rise toward the top of the lamp
tube. Thus, in order to maintain the arc at the focal point of
reflector sheet 32, sockets 37 must be appropriately
positioned.
The top wall of housing 36 is provided with a plurality of indented
louvers 38, while the inwardly turned portions at the bottom edges
of housing 36 are provided with a plurality of small holes 39. Left
end wall 36b of housing 36 is provided with circular exhaust
opening 42, surrounded by outwardly extending cylindrical sleeve
43. A flexible conduit (not shown) from a suction blower (not
shown) is adapted to be attached to sleeve 43 to draw air into
housing 36 through louvers 38, with such air circulating over the
rear surface wall 36a to cool reflector 32. Holes 39 along the
lower edges of housing 36 are provided for drawing off of ozone,
generated by ignited lamp 31, especially during warm-up thereof,
into the air stream generated by the suction blower shown
schematically in FIG. 1 as dual speed fan 46.
The inner surfaces of shutters 33, 34 are polished to reflect the
energy from lamp 31 and cooperate with reflector sheet 32 in
concentrating this energy. Baffle sheets 41b, 41c, inboard of end
walls 36b, 36c respectively, are provided with reflecting surfaces
to reflect energy back into the work area and assist reflector
sheet 32 in preventing energy intensity drop-off at the end regions
of reflector 32. Baffle sheets also serve to partially shield
sockets 37 from the heating effects of lamp radiation. Concave wall
36a in the regions between baffles 41b and 41c and their respective
near end walls 36b, 36c are provided with apertures 83 through
which cooling air is drawn over sockets 37. Thus, fan 46 creates a
suction on negative pressure, which causes air to flow in chambers
80b, 80c past the lamp ends in sockets 37 and through housing
chamber 79, in such a manner that sockets 37 and reflector 32 ae
cooled, yet little if any air moves past the major portion of the
lamp body.
Shutter sections 33, 34 are hingedly connected at 47, 48 to the
free edges of concave housing wall 36a along the entire length
thereof. Follower rollers 51, 52 are secured to the free edges of
the respective shutter parts 33, 34 and are disposed to move within
slot 53 of operating member 54. Upward movement of upper 54 is
effective to force rollers 51, 52 to converge, thereby operating
shutter 33, 34 from the open position of FIG. 3 to the closed
position of FIG. 4.
In operation conveyor speed control 56 (FIG. 1), acting to control
the speed of drive sprocket 12, feeds signals to control 55, which
sequentially operates the shutters of lamp reflector assemblies
26-29. More particularly, as work conveyor 11 slows down, the
number of shutters operated to close positions is increased so as
to prevent overheating of the work. That is, as printed sheets 15
move at a slower rate they are in the field of radiant energy
source 25 for a longer time so that in order to maintain the total
quantity of radiant energy impinging on printed sheets 15 to a
desired level it is necessary to decrease the available energy from
source 25 that is applied to printed sheets 15. This is
accomplished by closing the shutters of those lamp reflector
assemblies 26-29 that are not required.
Operation of the shutter means 33, 34 for each of the assemblies
26-29 is coordinated by control 60, so that upon closing of shutter
33, 34 lamp voltage is reduced to a point where current through
lamp 31 is at a standby level, much lower than the operating
current level. At the same time reflector cooling is increased,
through increase of blower motor speed or operation of a damper
(not shown). It is noted that standby current is at a level which
will maintain lamp 31 in a fired condition. Conversely, opening of
shutter 33, 34 is accompanied by an increase in lamp voltage and a
decrease in the amount of cooling air impinging on stationary
reflector 32. Increased cooling is required when shutter 33, 34 is
closed even though lamp voltage is reduced, in that lamp 31 is in a
substantially enclosed region that does not have the extensive
opening that is present when shutter 33, 34 is open.
Cooling plate 21 is preferably water-cooled, and is positioned so
as to shield the other elements of apparatus 10 from the rays of
radiant energy source 25. This is particularly important in a sheet
printing machine, as shown, rather than in a web machine, because
of the fact that there are extensive spaces between adjacent
sheets. In the absence of cooling plate 21, such spaces between
sheets 15 would permit rays from energy source 25 to impinge upon
and heat other elements of apparatus 10, either to the point of
destruction or to a point where they become so hot that contact by
sheet 15 would be sufficient to cause a fire.
Although there have been described preferred embodiments of this
novel invention, many variations and modifications will now be
apparent to those skilled in the art. Therefore, this invention is
to be limited not by the specific disclosure herein but only by the
appending claims.
* * * * *