Can transport

Can bodies are held by means, such as a vacuum, magnetic or other means onto rotating, disc-shaped pads which accompany the cans throughout an indexing route. A can centering guide positions each can on the center of one of the pads to insure eventual alignment with spray guns at two spray stations downstream. A spinner-drive belt encircles a turret and forms a substantially continuous rotational drive for spinning the can-bearing pads. When a vacuum means is employed, the vacuum means comprises a vacuum manifold in the rear of the turret and has manifold groove for vacuum communication with the can through the vacuum pad. As the can-bearing vacuum pads pass along the manifold groove, the cans, being securely centered on the vacuum pads, rotate at the same velocity as the belt-drive vacuum pads.

BACKGROUND OF THE INVENTION 
The interiors of can bodies must be coated to protect against corrosion and 
to insure quality control of the product. For efficient processing of 
millions of such cans, it is imperative that the interior coating be 
applied rapidly, uniformly, and economically. To this end, indexing 
turrets have been employed wherein a coating spray is applied to can 
interiors as the open-ended cans are indexed past coating-spray guns 
located at one or more spray stations along the turret indexing route. 
A common problem associated with current turret arrangements is the lengthy 
turret dwell time required for satisfactorily spraying the interior of 
each can. 
A further problem is the misalignment both of the can center with respect 
to the center of the can moving means and of the can interior with respect 
to the spray gun. Possible adverse consequences of such misalignment 
include uneven spray application, spray buildup on some interior surfaces, 
waste of spray and denting and damaging of the cans. 
Inventions of earlier vintage sought to reduce the time spent at spray 
stations. Accordingly, rather than move nozzles around to spray all 
portions of a can's interior, cans were rotated to spread the spray around 
the can interior. Can rotation has generally been imparted by drive belts 
positioned tangentially to the can and in direct contact with the can 
exterior. However, direct contact with the drive belts has had a tendency 
to force the can from the center of its transport means, resulting in the 
undesirable misalignment discussed above. Further, such direct contact has 
had a tendency to scratch, dent or otherwise damage the can exterior. 
Scratches cannot be tolerated, especially if the can has been previously 
printed with exterior decorations. Moreover, rotation of the can in most 
earlier devices has been inefficient, since a delay has occurred while the 
can was being accelerated to a satisfactory rotational velocity at the 
spray station. 
In general, as cans journey through a turret mechanism they are moved by a 
starwheel structure having either pockets or rollers for the cans; and, 
when a can is not securely centered on its transport means as it is 
carried through the turret arrangement, there is the hazard of denting and 
damaging the cans, which are made as light weight as possible. 
Another prior art problem relates to overspray. That is, since 
manufacturers have had no assurance of consistent, accurate can alignment, 
they have had to increase the spray dosage to maintain a satisfactory 
coating on the can interiors. At times, therefore, this excess spray 
builds up unpredictably and uneconomically in the can interior, and some 
excess spray must be drawn away through a vent stack and wasted. 
The prior art has endeavored to combat the above problems by firmly 
mounting the can at the spray stations by use of a vacuum means. However, 
the vacuum mounts have occurred only at the spray station with little or 
no assurance of accurate can centering with respect to the transport 
mechanism or the spray gun. 
In view of the above problems, an object of this invention is to provide a 
can spraying apparatus which will economically and uniformly distribute a 
coating on can interiors. 
Another object of this invention is to increase the turret indexing 
frequency by eliminating the time heretofore wasted by a rotational "warm 
up" at or proximate the spray station. 
A further object of this invention is the reduction of can damage and can 
dents that have resulted from prior can spraying devices. 
Still another object of the invention is to reduce the amount of spray 
required for coating can interiors; and, even another object of the 
invention is the reduction of waste by reducing the amount of overspray. 
SUMMARY OF THE INVENTION 
Cans are held by vacuum, magnetic or other means onto rotating, disc-shaped 
pads which accompany the cans throughout an indexing route. A can 
centering guide positions each can on the center of one of the pads to 
insure eventual alignment with spray guns at two spray stations 
downstream. In a first embodiment, this can centering guide is an 
adjustable guide which contacts the can bodies. In a second embodiment, 
this guide is supplemented by or replaced by a guide forming a portion of 
the pads. A spinner-drive belt encircles a turret and forms a 
substantially continuous rotational drive for spinning the can bearing 
pads. When a vacuum means is employed to hold the cans on the pads, the 
vacuum means comprises a vacuum manifold in the rear of the turret and has 
a manifold groove for vacuum communication with the can through the vacuum 
pad. As the can bearing vacuum pads pass along the manifold groove, the 
cans, being securely centered on the vacuum pads, rotate at the same 
velocity as the belt-driven vacuum pads.

Referring to FIG. 1, a turret indexing mechanism is generally denoted 20. 
An indexing shaft 22 in the center of the turret mechanism 20 imparts a 
counter-clockwise rotational motion as generated by a turret drive means 
located on a frame assembly not shown in FIG. 1. Since it is not the 
purpose of the present invention to focus on the turret drive means, such 
structure will not be further described at this time. It should be noted, 
however, that a purpose of this invention is to reduce the time which cans 
spend during spraying and, therefore, it is desirable to move them through 
the turret mechanism 20 as rapidly as practical. 
Emanating from the indexing shaft 22 is a starwheel 24 comprising a front 
starwheel plate 26 and a back starwheel plate 28 (best seen in FIG. 2). 
Each of the plates 26 and 28 contains a plurality of starwheel pockets 30, 
with the pockets of plate 26 being positionally aligned with corresponding 
pockets of plate 28. The starwheel pockets 30 accommodate the cans as they 
are ushered around the indexing route. Hence, it is inconsequential 
whether the starwheel is of the pocket design (as shown) or of the 
conventional roller design. 
In the FIGURES, six starwheel pockets 30 are shown with the result that 
indexing occurs in 60 degree increments. As displayed in FIGS. 1 and 6, 
during a turret dwell period the starwheel pockets 30 are in significant 
positions corresponding to processing stations along the indexing route. 
Specifically, the significant processing stations are denoted as infeed 
station 42, first spray station 44 and second spray station 46. The 
salient features of the present invention can be applied to turret 
arrangements having more or less processing stations by substituting 
appropriate starwheel plates with the desired number of pockets and by 
adjusting the indexing and driving means to index in the appropriate 
increments. 
Adjacent infeed station 42 is infeed chute 48 which supplies cans to the 
turret indexing arrangement 20. The cans may be currently conventional 
drawn and ironed aluminum or steel can bodies for beverages, open at one 
end and integrally closed at the other, or may be of other constructions 
and materials for other products. The cans fall by gravity through infeed 
chute 48 in single file, pushing the can first in line into infeed station 
42 as it becomes vacant. A timed released gate (not shown) at the base of 
infeed chute 48 prevents jamming and prohibits entry of the first can in 
the infeed chute until a predetermined number of cans are stacked within 
the infeed chute. 
A discharge chute generally denoted 50 includes a can scoop rail 52 for 
removing the cans from the indexing mechanism 20. 
Behind starwheel 24 and firmly affixed to indexing shaft 22 is a 
disc-shaped vacuum pocket plate 60 (see FIGS. 2, 3, and 5). Vacuum pocket 
plate 60 has a diameter slightly greater than that of starwheel plates 26 
and 28 so that its rim can be seen from the front of the turret indexing 
mechanism in FIG. 1. A front surface 62 of vacuum pocket plate 60 has a 
circular elevated collar portion 64 (see FIG. 5) surrounding a shaft 
engagement hole 66 which extends through the center of the vacuum pocket 
plate 60. 
Shaft engagement hole 66 is notched at 68 throughout said hole, thereby 
permitting the vacuum pocket plate 60 to receive indexing shaft 22 and to 
be locked thereon (see FIG. 4). Accordingly, vacuum pocket plate 60 is 
indexed at the same velocity as the starwheel 24. 
A back surface 70 of vacuum pocket plate 60 has a raised circular rib 72 
along the circumference of the plate 60 in FIG. 5 and is concentric with 
shaft engagement hole 66. Rib 72 on vacuum pocket plate 60 has six holes 
74 bored therethrough in positions 60 degrees apart to correspond with the 
center of the six starwheel pockets 30 (See FIG. 4). 
Mounted on vacuum pocket plate 60 between plate 60 and starwheel plate 28 
are six steel disc-shaped vacuum pads 90. As seen in FIG. 1, the six 
vacuum pads 90 are aligned with the six starwheel pockets 30. During most 
of the turret route each vacuum pad 90 has a can sucked thereon and the 
pad accompanies the can throughout the indexing route. 
Referring now to FIG. 3, the center of each vacuum pad 90 receives a hollow 
fastener, such as a hexagonal vacuum pad bolt 92, through which a vacuum 
is communicated to the can riding on the pad. The vacuum pad bolt 92 
extends through the vacuum pad 90; through a vacuum pad bearing 94 
contained in the vacuum pad 90; through a vacuum pad spacer 96 positioned 
adjacent bearing 94; and, finally, through one of the six holes 74 bored 
through rib 72 of vacuum pocket plate 60. In this manner, the vacuum pad 
90 is free to spin while mounted on the vacuum pocket plate 60, which is 
indexed with the starwheel 24, while connected to the vacuum. 
The vacuum pad further comprises a can bearing surface 98 connected to two 
concentric annular ribs 100 and 102. External rib 100 contacts a 
spinner-drive belt 104 which imparts a rotational force to spin the vacuum 
pad 90. Internal rib 102 is notched to receive beveled retainer ring 106, 
thereby forming a circular cavity in the vacuum pad 90 which houses vacuum 
pad bearing 94. 
As seen in FIGS. 4 and 5, immediately behind vacuum pocket plate 60 is a 
kidney-shaped vacuum manifold 120. Vacuum pocket plate 60, being locked to 
the rotating indexing shaft 22, skims a front surface 122 of vacuum 
manifold 120 during indexing. The stationary vacuum manifold 120, which is 
not coupled with the indexing shaft 22, is mounted within a frame assembly 
23 as hereinafter detailed. 
FIG. 1 reveals that the vacuum manifold 120 is positioned in the vicinity 
of infeed station 42; first spray station 44; and second spray station 46. 
FIG. 4 (as well as FIG. 1) illustrates a semicircular channel or vacuum 
manifold groove 124 cut in the vacuum manifold 120 from point 126 to point 
128. As shown in FIG. 1, point 126 resides slightly past the center of 
infeed station 42 as the turret indexes. Similarly, point 128 resides 
slightly past the center of second spray station 46. In the illustrated 
embodiment, the vacuum manifold groove 124 is 0.5 inch (1.27 centimeter) 
wide and extends 0.5 inch (1.27 centimeter) deep into the vacuum manifold 
120. 
A vacuum pump interface hole 130 is radially bored into the vacuum manifold 
120 to connect with the vacuum manifold groove 124, thereby allowing 
communication with a vacuum source (not shown) for maintaining the vacuum 
at 500 mm. mercury, in a preferred embodiment. Also bored through the 
vacuum manifold are holes 132 and 134 (FIG. 5) for accommodating vacuum 
manifold stud bolt 136 and stud bolt 138, respectively, which anchor the 
vacuum manifold 120 in frame member 23, as seen in FIG. 4. Since hole 132 
intersects the vacuum pump interface hole 130, vacuum manifold stud bolt 
136 is drilled perpendicularly to the stud shaft to allow air passage 
through the bolt. 
FIG. 5 exhibits the attachment of the vacuum manifold 120 within the frame 
member 23 by means of the vacuum manifold stud bolt 136, washer 140, 
retaining spring 142 and screw cap 144. Although stud 138 is not drilled 
to facilitate air passage, the manner of fixation is comparable. 
Encircling the turret indexing arrangement 20 is spinner-drive belt 104 
which loops around all vacuum pads except that particular vacuum pad which 
happens, at any given time, to be located at idle turret position 160 in 
FIG. 1. Spinner-drive belt 104 also contacts drive pulley 162 of 
spinner-drive motor 164. In the illustrated embodiment spinner-drive belt 
104 is a flat belt approximately 0.5 inch (1.27 centimeter) wide and 
flexible enough to absorb the slight difference in belt length as indexing 
mechanism 20 indexes through the different positions. Spinner-driver belt 
104 forms a continuous rotational drive for the vacuum pads 90 and the 
cans mounted thereon. The rotational speed of vacuum pads 90 can easily be 
changed by altering either the speed of the spinner-drive motor 164 or the 
size of the drive pulley 162. The spinner-drive belt can be driven in 
either direction, but it is preferred that its direction be opposite that 
of the starwheel. 
The spinner-drive belt 104 can be driven at a relatively high velocity; 
and, in this manner, the vacuum pads 90 and the cans mounted thereon are 
rotated at high velocity at the coating stations 44 and 46 so that more 
"wraps" of spary (layers of coating) are delivered to the interior of the 
cans at the spray stations 44 and 46. This increased number of "wraps" 
provides a more uniform interior coating than has been obtained on cans 
using conventional spray structures. That is, as will be described more 
fully later, the indexing mechanism 20 permits each can to dwell at the 
spray stations for a given period of time; and the faster the cans are 
spun during that time, the more time a given point of the can's interior 
will pass a point on the spray pattern. 
Additionally, the cans are rotated at this high speed without being driven 
by a mechanism in contact with their side walls. This eliminates dents and 
other damage to the can bodies and/or the decorative printing which is 
often placed on the can bodies prior to their interior spray coating. This 
also eliminates the tendency for can driving systems to force the cans out 
of alignment with the spray pattern and thus cause overcoating and 
undercoating of various regions of the cans. 
Attached to infeed chute 48 and positioned between infeed station 42 and 
first spray station 44 in this embodiment is a can centering guide 180. A 
can contacting surface 182 thereof forms a radial guide concentric with 
the center 184 of the indexing shaft 22. Adjustment screw 186 is used to 
selectively vary the radial distance from the center 184 of the indexing 
shaft 22. In this respect, the can centering guide 180 can be pre-set by a 
dial indicator for reasons to be discussed more fully shortly. Similarly, 
a leg 183 to which centering guide 180 is attached is movable up and down 
in the direction of arrow 185 to adjust the overall distance of contacting 
surface 182 from center 184 and the rotating cans. 
Other structural features of the can spray mechanism include can sensors 
190 and 191 for detecting the location of cans traveling through the 
indexing turret and initiating a timing sequence for spraying at first 
spray station 44 and second spray station 46. Each spray station is paired 
with a can sensor 190. When passing by spray stations 44 and 46, the cans 
are guided, but not contacted, by turret guard rail 192. 
FIG. 6 shows spray guns 194 and 196 positioned at first spray station 44 
and second spray station 46 respectively. Spray guns 194 and 196 apply a 
thin, uniform coating to the interior of the open-ended cans as they are 
spun on vacuum pads 90 in the manner described above. 
Focusing now in the operation of the can interior spray mechanism, as the 
cans queue up in the infeed chute 48, gravity draws the first can into the 
vacant starwheel pocket 30 at infeed station 42. FIG. 6 illustrates how 
the cans, in single file, push the lowermost can into infeed station 42 as 
that station becomes vacant during a turret dwell. 
As a can falls into starwheel pocket 30 at infeed station 42, the can 
encounters front and back starwheel plates 26 and 28, as well as the 
vacuum pad 90. While in infeed station 42 the can is not rotating. Vacuum 
pad 90 is rotating, however, since it is driven by spinner-drive belt 104. 
The rotation of the vacuum pad 90 is not imparted to the can at this 
point, because the can is not in communication with the vacuum while in 
infeed station 42. 
As the turret begins to index in the counterclockwise direction the first 
of a sequence of significant steps occurs. That is, when the turret has 
indexed just a few degrees past infeed station 42, the vacuum pad 90 
communicates with vacuum manifold 120 to promptly suck the can onto vacuum 
pad 90 at point 126 so that the can begins to spin with the same 
rotational velocity as the belt-driven vacuum pad 90. That is, vacuum from 
manifold 120 is delivered to pad 90 through hollow fastener 92 and hole 74 
of vacuum pocket plate 60. Hence, while the vacuum pad 90, vacuum pocket 
plate 60 and hole 74 ride over the vacuum manifold groove 124 from point 
126 to point 128, the can is in continuous communication with the vacuum 
manifold 120; and, the can rotates continuously as it is moved between 
points 126 and 128. 
The second significant step upon leaving infeed chute 42 is the centering 
of the can on the vacuum pad 90 by means of can centering guide 180. The 
can is centered on the vacuum pad 90 to reduce the quantity of spray 
required and the possibility of can damage as aforementioned. As the can 
encounters the can centering guide 180, the outer diameter of the can 
rolls against the can contacting surface 182 which is concentric with the 
center of the indexing shaft 184 and radially spaced therefrom so that 
clearance will be permitted only when the can is at the center of the 
vacuum pad 90. As vacuum pad 90 spins, can contacting surface 182 keeps 
nudging the can to the center of vacuum pad 90. To move past the can 
centering guide 180, the can diameter must be centered on the center of 
the vacuum pad 90 so that the loci of the outside surface of the can is 
concentric with the can contacting surface 182. 
The third significant event occurring after departure from the infeed chute 
42 is the detection of the can by the can sensor 190 located between 
infeed chute 42 and first spray position 44. Upon detecting the can by 
photoelectric or other means, can sensor 190 triggers a timing sequence 
for the spray gun 194 in FIG. 6. Likewise, after the can has received a 
partial coat of spray at first spray station 44, can sensor 191, located 
between first station 44 and second spray station 46, is activated by the 
presence of the can and initiates a timing sequence for spray gun 196 at 
second spray station 46. 
Preferably, the coating is partially applied at each station. That is, at 
station 44 spray gun 194 is aimed at the bottom of the can, and, at spray 
station 46 spray gun 196 concentrates on the cylindrical sides. Although 
some overlapping results, it has been found that this manner of spraying 
requires less spray overall. 
As noted above, at each spray station the vacuum pad 90 and can mounted 
thereon are rotating since they are driven by spinner-drive belt 104; and, 
in a preferred embodiment, the rotational speeds of the cans range between 
2,000 and 2,500 rpm. In this respect, the can speed can be adjusted by 
varying the size of drive pulley 162 or the speed of spinner-drive motor 
164. 
In any event, the faster the rotational velocity, the greater the number of 
spray wraps per unit of time in each can; and, the greater the number of 
wraps, the more even the coating application. Moreover, it should be 
appreciated that cans have customarily been "oversprayed" simply to 
provide a minimum coating thickness at all portions of their interior. 
Hence, by providing a more uniform coating, less spray is required; less 
time is required at the spray stations; and, the unit can move faster. 
Additionally, since the can is centered with respect to the vacuum pad 90 
and the pre-set spray guns 194 and 196, little or no spray is lost or 
wasted due to misalignment of the spray gun and can. 
In the above regard, it has been noted that prior systems have used driving 
belts to contact the can peripheries to rotate the cans during spraying. 
Those systems, however, have a tendency to push the cans against the 
starwheel pocket or the like and displace the cans from the center of the 
spray pattern. The structure of the instant invention, however, permits 
the cans to be continuously spun without being moved out of the desired 
central alignment with the spray pattern. Hence, not only is a more 
uniform coating obtained, but there is far less overspray to go out a vent 
and pollute the atmosphere. 
After the final coat of spray is applied at second spray station 46, the 
turret again indexes. When the turret has indexed just a few degrees past 
the second spray station 46, the vacuum pad 90 and the can mounted thereon 
traverse point 128 on the vacuum manifold groove 124. Since point 128 is 
the end of the vacuum manifold groove 124, vacuum pad 90 and the can 
mounted thereon are severed from the vacuum. At this point, the vacuum pad 
90 continues to rotate since it is driven by spinner-drive belt 104. The 
can itself is no longer secured to vacuum pad 90, but its rotational 
momentum causes it to continue to spin. At starwheel pocket 198 the can is 
stripped from vacuum pad 90 by can scoop rail 52. The can then falls by 
gravity through the discharge chute 50. 
A modified can transport mechanism is illustrated in FIGS. 7 and 8. With 
one exception, to be noted below, this embodiment is identical in all 
respects to the embodiment of FIGS. 1-6 and operates in the same manner. 
Thus, while the corresponding reference numerals have been repeated in 
FIGS. 7 and 8, their operation need not be repeated. 
The modification of this embodiment concerns the vacuum pads 90. In this 
embodiment, the generally planer pads 90 include a guide boss 200. This 
boss 200 is generally disc-like, and is sized and shaped on its peripheral 
surfaces to permit a can body to fit thereover. The boss 200 is open at 
its center to the vacuum. The boss 200 may be attracted to or formed as an 
integral portion of vacuum pads 90. 
When a can body is drawn by the vacuum to the vacuum pad 90, it is drawn 
from the starwheel 24. While the starwheel 124 does not alone always 
center the can body exactly on the pad 90, as previously mentioned, the 
deviation from center is, while not acceptable for spraying purposes, as 
mentioned above, not excessive. As the can body is drawn to vacuum pad 90, 
if it is not exactly centered when drawn to the vacuum pad 90, it will 
rock on the guide boss 200. That is, the can bottom will align itself on 
the guide boss 200, due to the vacuum and the spinning of the can body, so 
that the can bottom fits over the guide boss 200 and the can body is 
centered on the vacuum pad 90. 
The guide boss 200 may be used in addition to the can centering guide 180. 
However, the guide boss 200 may replace the guide 180. When this is 
accomplished, there is no contact of the peripheral surfaces of the can 
bodies while they are rotating on the vacuum pads 90. This further reduces 
any change for damage to the can body or the decorative printing thereon. 
While the invention has been particularly shown and described with 
reference to preferred embodiments thereof, it will be understood by those 
skilled in the art that various alterations in form and detail may be made 
therein without departing from the spirit and scope of the invention. For 
example, more rotating vacuum pads can be used; more spray stations can be 
employed; and, where steel cans are used, the bottom engaging means can be 
electro-magnetic rather than the illustrated vacuum-type. 
While present preferred embodiments of the invention have been illustrated 
and described, it may be otherwise embodied and practiced within the scope 
of the following claims.