Note: Descriptions are shown in the official language in which they were submitted.
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REVERSE SPRAY ELECTROSTATIC
AIR/POWDER STRIPE APPLICATOR
This ~nvention relates in general to new and
useful improvements in the interior side striping of con-
tainer bodies, and more particularly to a novel powderapplicator.
There has been recently developed a powder appli-
cator wherein there is incorporated in th0 powder spray
pipe a centrifuge arrangement which causes the powder to
flow into one cr~ss sectional segment of the pipe, separat-
ing the powder from the carrier gas, and thereby distribut-
ing the powder to a nozzle orifice in a preselected segment
only of that orifice for application of the powder in a
stream~ This development, while bene~icial, is thought to
have two deficiencies. First, when using a 360 loop as is
required with the prior centrifuge arrangement, the orifice
must be directed in the same direction as the movement of
the can bodies past the nozzle. Secondly, a friction drop
or loss in the powder supply tube is reduced while the
desired centrifu~e action is obtained.
In addition, inasmuch as the can bodies with the
powder stripe applied thereto are heated and the heat
source is a gas flame, fire can result when ihe powder is
directed in the direction of can body movement.
In accordance ~i~h this invention, it is proposed
to utilize the centrifuge principles while at the same time
reversing the direction o~ pow~er ~low sv that it opposes
the direction of ~o~ement of the can bodies. In making
this change, it has been ~ound that the necessary centri-
fuge action can be obtained with a reverse bend of generally
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180 spray loop. Further, i~ has been found that the fric~
tion loss within the loop is xeduced and that a better flow
of the powder stream can be ef~ected.
Further, lt has been ound ~hat b~ direcklny the
powder stream in general oppositlon to the dlrection o
movement of the can bodies, the film or powder weight vari-
ation along the side seam is less. There ls a slighk de
crease in powder thickness at the "lead" edge of the can
body, but the decrease in powder thickness is less than the
"tail off" decrease using a conventional spray applicator.
Priox devices other than that discussed above
have been provided for interiorly side striping can bodies
and the like including the patent.to Manuel et al 3,526,027
granted September 1, 1970, and the patent to ~inkless
3,678,336 granted July 18, 1972.
With the above and other objects in view that
will hereinaf~er appear, the nature of the invention ~ill
be more clearly understood by reference to the following
detailed description, the appended claims, and the several
~0 views illustrated in the accompanying drawings.
IN TH~ DRAWINGS:
_
Figure l is a schematic side elevational view
of a body maker having incorporated therein a powder appli-
cator in accordance with this invention.
Fi~ure 2 is an enlarged fragmentary longitudinal
vertical sectional view taken through the powder applicator
and shows the general details thereo.
Figure 3 is a transverse vertical sectional view
taken generally along ~he line 3-3 of Figure 2.
. Referring now to Figure 1, it will be seen that
there is illustrated a body maker 10 which may be of a
conventional type, but in accoxdance ~ith the illustrated
form of can body is one which fo~ms can bodies ~ith ~elded
. side.seams~ The body maker has attached to the horn thereof
in a conventional manner a po~der applicator r g~nerally
identified by the numeral 11. The po~der applicator 11
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includes a suitab.le support, generally identified by the
.numeral 12, which forms a continuation of the horn and Which
may function as a.support for can bodie~, although the can
bodies could e~ually as well be carried by e~ternal support~
The support.12 has extending into the lead end
thereof a powder supply line 13 which is suitably connected,
as shown in Figure 1, to a powder dlspenser 14 wherein
powder is entrained in a suitable carrier gas which may be
air. The carrier gas entrained po~der is directed through
the spray tube 13.into the interior of the support thr~u~h
the body maker 10 until it reaches a position adjacent the
desired location of powder application, as is best shown in
Figure 2. The supply tube 13 is provided with a centrifuge
section 15 in the form of a reverse bend which extends
through an arc on the order of 180.
It is to be understood that the radius of curva-
ture of the reverse bend which ~orms the centrifuge section
15 is such that when related to the velocity of the carrier
gas entrained powder, the powder will be thrown outwardly
against the radial outer wall of the tube, and thus there
will be effected a layering or stratifying action with the
powder becoming a dense stream separate and apart from the
carrier gas.
The supply tube 13 terminates in a nozzle general-
ly identified by the numeral 16. Basically, the nozzle 16is in the form of a block having a bore 18 opening through
one face thereof and receiVing the terminal end of the
supply tube 13. The bore 18 opens lnto an orifice 20 which
has a longitudinal axis selectively disposed at ~ slight
angle to the path of movement of can body side seams or
substantially parallel thereto. It is to bP understood
that the powder stream is concentrated in the lower part of
the orifice 20 which is preferably o~ an expanded configur-
ation as shown in Figure 2.
The block 17 is mounted on an inverted U-shaped
support 21 by means of a transverse pivot pin 2~. The
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support 21 has adjustably mounted on the central portion
thereof adjusting screws 23 through which the tilting of
the orifice 20 is controlled, and the orifice 20 is main-
tained.in a selected angular xelation with ~espect to the
path of movement of can bodies.
~ s Will be readily apparent, as c~n bodies B,
wh;.ch are moved in spaced sequence along the predetermlned
path by a conveyor chain 24 having lugs 25, moVe past the
noz21e 16, a dense stream.of powder is di.rect~d onto the
side seam area of each can body B as is diagrammatically.
sho~n. Since the powder is applied in a dense stream,
and is for the most part not conveyed by the carrier gas,
it flows onto the can bodies in the same general manner
as a liquid with a minimum of overspray and powder particle
bounce.
It is to be understood that the powder particles
are to be electrostatically charged so that they will re~
main in position on the interior surface of the can bodies
as the can bodies pass ~urther down the can line and are .
subjected to heating to a temperature which will e~fect
fusing of the powder particlesO To this end, downstream
of the nozzle 16, the support 12 is provided with an elon-
gated opening or channel 26 of a cross section best shown
in Figuxe 3. The channel 26 carries a pair of elongated
plates 27 which define side walls of a sealed chamber de-
fined between a pair of brushes 28 carried by the support
12 and internally engaging the can bodies on opposite sides
of the side seam area. .
The sealed area has projecting therethrough a
longitudinal line of corona charging pins 30 which effec-
tively charge the powder particles ~hich have passed into
the sealed area. The corona charging pins 30 are connected
to a common source of high voltage.d.c. current by a con-
ductor 31 with there being a resistor 32 between each charg-
ing pin 30 and the conductor 31 so as to provlde for uniformcurrent distribution among the line of charging pins.
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It is to be understood that.the channel 26 will
be of sufficient length so as to permit an adequa~e charging
o the powder particles disposed within khe sealed area so
that all of the particles will adhere to the interior ~ur-
face.of the can body B, preferably alony the side seamarea. The side seam area will later be heated in a conven-
tional manner to effect fusing of the powder particles to
the can body, thereby preventing the existence o~ any pow-
der particle ~hich is so adhered to the interior of the can
body whereby.it may later become-disengaged and become
either a contaminant for ~ood products or foreign matter
which cou~d plug the spra~ dispensing mechanism should the
can body be part of an aerosol container.
It is to be understood that the porous plates 27
lS define, together with the support 12, exteriorly of the
sealed area chambers 33. The chambers 33 are disposed
within a channel 34 formed in the upper part of the support
- 12 and carrying the conductor 31 and the resistors 32. The
channel 34 opens into the chambers 33 through passages 35,
as is shown in Figure 3,
A suitable gas (air) i5 directed into the channel
34 through a spray tube 36 which extends through the body
maker horn in the same manner as the spray tube 13. The
tube 36 also carries a lead conductor 37 for supplying the
electrical energy to the conductor 31.
The gas (air) entering into the channel 34 passes
.into the chambers 33 and through the plates 27 so that
diffused air is directed into the sealed space~ The dif-
fused gas serves to keep clean the sides.of the sealed
chamber as well as the corona charging pins 30.
I~ desired, there may also be pxovided a hopper
37 for receiving excess powder. The hopper 37 will extend
below the path of travel of the can body as shown in Figure
1, and be positioned for receiving particles which exit
from the nozzle 16 between can bodies. A vacuum may be
drawn in the hopper 37 so as to aid in drawing out any loose
`~-~ powder particles which may exist.
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It is to be understood that the reverse bend in
the supply tube 13 and the mounting of the nozzle 16 so as
to direct a powder stream in opposition to the direc~ion of
movement of the articles being coated may be ut.ilized in
other environments.
Al~hough only a preferred embodiment of the inven-
tion has been specifically illustrated and described herein,
it is to be understood that minor.variations may be made in
the powder applicator without departing from the spirit and
scope of the invention as defined by the appended claims.
