(54) CONTINUOUS CAN PRINTER(71) We, COORS CONTAINER COM- PANY, a Corporation organised and existing under the laws of the State of Cororado,United States of America, of 1755 West 32nd Avenue, Golden, State of Colorado, 80401, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:This invention relates to a continuous can printer. The major elements of such printers generally comprise infeed mechanism, loading means for placing cans on mandrels, a printing blanket wheel for transferring an image from the blanket cylinder to a container, and transfer mechanism for moving decorated cans to pins of a chain conveyor for passage through a curing and drying oven.
Infeed mechanisms heretofore have comprised a star wheel for delivering cans successively to a pocket wheel, as in U.S. 3261,281; or have comprised a combination of elements, namely, a star wheel and a screw conveyor, as in U.S. 3766,851. The infeed mechanism carried cans to a pocket or cradle wheel provided with pockets for holding cans in axial alignment with mandrels on a mandrel wheel. Pockets or cradles disclosed in the aforementioned patents are either retractable in radial directions or movable in axial directions to carry cans to mandrels.
The mechanism shown in U.S. patent No.
3016,153 employes push rods moving in axial directions to place cans on mandrels and also for transferring decorated cans from the mandrels to a pin chain conveyor. In the prior art constructions, the infeed means utilized various moving parts, and the discharge means employed double cams and complex mechanisms for transferring decorated cans to a pin chain conveyor.
The invention relates to a continuous can printer comprising a rotatable pocket mandrel wheel and means for printing cans thereon, a can infeed track for guiding cans under force of gravity from a supply to pockets on the circumferential surface of the rotatable pocket mandrel wheel, said track approaching the wheel in a nonradial path and forming an oblique angle with a tangent to the wheel at the intersection of the track and the wheel in the direction of wheel rotation, the track having an outlet portion that curves in the direction of wheel rotation and extends down to the depth of the pockets to redirect the path of the cans closer to the path of the pockets moving with the wheel; said pocket wheel having continuously adjacent pockets on its surface, each pocket having a leading and a trailing surface, the leading surface being smoothly contoured to recede under the path of a can entering the pocket from the track as the wheel rotates, without substantially interfering with the gravity induced motion of the can, said trailing surface contoured in an arcuate segment to seat the can and move it away from the infeed track with the rotation of the wheel when the can is fully in the pocket.
This application is divided from Application No. 53204/77 (Serial No. 1591882) which describes and claims a can printer incorporating particular means for discharging printed cans from a pocket mandrel wheel.
In the apparatus of the present invention the pocket wheel preferably further comprises a mandrel axially aligned with each pocket for receiving the can from the pocket and supporting the can during contact with a rotatable printing blanket cylinder for decorating the can exterior; a vacuum source in each mandrel for drawing the can onto the mandrel; and a flexible spring element mounted adjacent the pocket wheel and contacting each can seated in the pocket to urge the can axially in the pocket, toward the adjacent mandrel, while said vacuum is applied through the mandrel to draw and seat the can on the mandrel.
In the accompanying drawings which illustrate a specific embodiment of the invention,Figure 1 is a front elevational view of a can printing machine embodying the invention.
Figure 2 is a sectional view of one of the transfer stations whereby decorated cans are transferred from a pocket mandrel wheel to suction cups on a transfer wheel.
Figures 3 and 4 are sectional views of a transfer vacuum head showing valving details.
Figure 5 is a fragmcntary elevational view of part of the infecd means.
Figure 6 is a top view of the container load area of Figure 1, on an enlarged scale.
Figure 7 is an elevational end view, on an enlarged scalc, of the means for transferring decorated cans to a pin chain.
As shown in Figure 1, cans 10 are cylindrical, provided with one closed end and an opposite opcn end. The cans are fed from a conventional track system to an inclined infeed chute 11 through which they move by gravity. The chute is provided with guide rails 12,13, and top guide 14. Cans pass into pockets 1 5 of a pocket mandrel wheel 16. As the wheel is rotated past the infeed chute, the can rolls down the profiled infeed guides and contoured pocket surface until it is fully seated in the pocket 15. There are no moving parts to wear, and correct infeed timing is accomplished by the pocket and its contour.
The closed end of each can is contacted by a spring shoc 1 7 which guides the can toward a mandrel 18 on wheel 16.
Vacuum is applied through the mandrel 18 and, with the guiding aid of the spring shoe17, draws and scats the can on the mandrel18 opposite the open end of the can. Rotation of the pocket mandrel wheel 16 in clockwise direction carries the can into contact with the printing blanket cylinder 19 where the image is transferred to the can 10.
Just before the printing contact, the end of the mandrel 1 8 is contacted by a pre-spin belt 20 on rollers 21 which brings the can on the mandrel to surface speed of the blanket cylinder 1 9. The belt is wrapped around and is driven by the blanket cylinder 1 9 to ensure preciscly matched surface speeds. The rollers 21 maintain tension on the belt 20. Ink is transferred to the blanket cylinder by inkers and plate cylinder 22. Four such inking stations are used in this machine.
Dccorated cans are transferred from the pocket mandrel wheel 16 to suction cups on the transfer wheel 24. The transfer area is indicated at 25 on Figure 1.
Figure 2 shows one of the transfer stations.
The transfer wheel 24 consists of 24 stations to ensure adequate time for transfer. The hub 30 is locked to a cantilevered shaft 31 which is driven in time with the pocket man drcl wheel 16. The flange 32 of the wheel hub 30 carries an angled slide shaft 33 secured by shoulder 34 and screw and washer 35 in bore 36. A housing 37 is slidably carried by sleeve portion 38 on shaft 33 and in turn carries vacuum head 40 and screw 41. The opposite end of the head 40 carries a rubber burner 42 and rubber suction cup 43. Link 44 is pivotally attached to the housing 37. A scalloped hub portion 45 carries a pivotally mounted arm 46 which carries a pair of cam follower rollers 47 supported on shaft 48.
The opposite end of the shaft 48 carries a coupling 49 pivotally attached to the link 44.
The followers 47 ride in box cam 50 which is secured against rotation by shaft support hub 5 1. Rotation of hub 30 causes cam followers 47 to ride up and down the swells of cam 50, thus rotating arm 46. Movement of this arm causes link 44 to pivot through coupling 49 and slide housing 37 down shaft 33, thus displacing suction head 40 in both axial and radial direction.
To transfer the decorated can 10 from the mandrels 1 8 to the transfer wheel 24, the can is blown off the mandrel 18 onto the suction cup 43 of the transfer suction head 40 where it is held by vacuum. Vacuum is applied to cup 43 through passages 52, 53, in said head, passages 54 and 55 in shaft 33, passage 56 in hub 30, chamber 57, passage 58 in hub 30, and rotary valve 59 connected to a source of vacuum. The rotary valve 59 is screwed into an end plate 60 bolted to hub 30 to form chamber 57. This chamber acts as a vacuum manifold, thereby placing a large volume of vacuum as close to the vacuum head 40 as possible.
During the transfer operation, cam followers 47 follow the path of the box cam 50 and cause link 44 to pivot in a counterclockwise direction, thereby causing housing 37 to slide down shaft 33. The resultant radial motion of the cup 43 causes it to take a path coinciding with the path of the mandrel 18. At the beginning of this common path, in the transfer area 25, air is blown through the mandrel to displace the can from the mandrel to the cup. The resultant axial motion of the cup removes the can completely clear of the mandrel. During this time, vacuum is applied to the suction head 40 through passages 54, 54a and 54b and through passages 53 and 52 to suction cup 43. Bushings 62 and 63 seal vacuum in this position.
As the can on the transfer wheel comes into the unloading area, the contour on cam 50 causes housing 37 to slide further down shaft 33. As the head 40 reaches unload point 65, vacuum passage is blocked by bushing 62. As housing 37 continues to retract, cut out 61 on shaft 33 straddles bushing 63, thereby venting passage 53 to atmosphere and breaking vacuum. At this point the pin chain 66 carries the can off the suction cup and on through the oven for drying.
As best shown on Figure 5, the pockets 15 in the peripheral surface of the rotating wheel 16 having a leading surface which slopes gradually downwardly to a can seating surface limited by a circular surface corresponding in cross section to a segment of the can circumference.
The use of the illustrated apparatus com prises feeding cans successively from a supply source directly to said stationary pockets 1 5 of the rotating pocket wheel 16 in a guided path by gravity, said infeed means and pockets being free of moving parts. The wheel has a mandrel opposite each pocket.
Spring means contact each can when it enters a pocket to start the can to move axially onto the mandrel while vacuum is applied through the mandrel, drawing and seating the can on the mandrel. The can is printed while held on the mandrel. After printing, the decorated can is blown off the mandrel onto a suction cup on a suction head which is part of a transfer assembly on a rotating transfer wheel. Movement of the suction head and cup radially downwardly on an angled shaft mounted on said rotating transfer wheel moves the cup in a path coinciding with the path of the mandrel, and blowing air through the mandrel at the beginning of the coinciding path displaces the can from the mandrel to the suction cup where it is held by vacuum.
Movement of the suction cup and head further down on the angle shaft blocks vacuum passage, releases the can from the cup and places it on a pin of a chain conveyor. All motion of the housing 37 carrying the vacuum head and cup 43 is in a radial and axial direction, accomplished by a single cam action.
WHAT WE CLAIM.IS:- 1. A continuous can printer comprising a rotatable pocket mandrel wheel and means for printing cans thereon, a can infeed track for guiding cans under force of gravity from a supply to pockets on the circumferential surface of the rotatable pocket mandrel wheel, said track approaching the wheel in a nonradial path and forming an oblique angle with a tangent to the wheel at the intersection of the track and the wheel in the direction of wheel rotation, the track having an outlet portion that curves in the direction of wheel rotation and extends down to the depth of the pockets to redirect the path of the cans closer to the path of the pockets moving with the wheel; said pocket wheel having continuously adjacent pockets on its surface, each pocket having a leading and a trailing surface, the leading surface being smoothly contoured to recede under the path of a can entering the pocket from the track as the wheel rotates, without substantially interfering with the gravity induced motion of the can, said trailing surface contoured in an arcuate segment to seat the can and move it away from the infeed track with the rotation of the wheel when the can is fully in the pocket.
2. A printer as claimed in claim 1 wherein said pocket mandrel wheel further comprises a mandrel axially aligned with each pocket for receiving the can from the pocket and supporting the can during contact with a rotatable printing blanket cylinder for decorating the can exterior; a vacuum source in each mandrel for drawing the can onto the mandrel; and a flexible spring element mounted adjacent the pocket wheel and contacting each can seated in the pocket to urge the can axially in the pocket, toward the adjacent mandrel, while said vacuum is applied through the mandrel to draw and seat the can on the mandrel.
3. A continuous can printer as claimed in claim 1 substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
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