Title:
CAN CARRIER TRIP MECHANISM IN CONTINUOUS CAN PRINTER
United States Patent 3851579


Abstract:
A trip mechanism for a continuously rotating can printing or coating machine having rotatable can shaft supports, which is operable to displace the support from a print blanket. The trip mechanism includes an eccentric sleeve between the shaft and a bore which is rotatable with the bore and about the shaft. In a normal position, the sleeve holds the shaft in position to effect contact between a can mounted thereon and the print blanket. A detector provides a trip signal in response to the absence of a can. A trip cam and trip cam follower pair are provided, one of which is mounted on the eccentric sleeve. The trip cam is thrown from a normal print to a trip position in response to a trip signal. The trip pair is positioned to engage one another when the cam is in the trip position to cause rotation of the sleeve whereby the shaft and can support are displaced away from the print blanket.



Inventors:
ZURICK A
Application Number:
05/360831
Publication Date:
12/03/1974
Filing Date:
05/16/1973
Assignee:
VAN VLAANDEREN CONTAINER MACHINERY INC,US
Primary Class:
Other Classes:
101/247, 118/668, 118/700
International Classes:
B41F17/00; B41F17/22; (IPC1-7): B41F17/22
Field of Search:
101/38-40,247 118
View Patent Images:



Primary Examiner:
Crowder, Clifford D.
Attorney, Agent or Firm:
Ryder, McAulay, Fields, Fisher & Goldstein
Claims:
What is claimed is

1. In a continuously rotating can printing or coating machine having a can support, the shaft of said can support being mounted within a bore of a continuously rotating carrier arm, the improvement of a trip mechanism to effect displacement of the can support from a print blanket comprising:

2. The trip improvement of claim 1 further comprising:

3. The trip improvement of claim 1 wherein:

4. The trip improvement of claim 2 wherein:

Description:
This invention relates in general to a continuous can printing apparatus and more particularly to a mechanism for preventing contact between the can support and the printing blanket when a can is missing from the support or when the can being carried is damaged.

BACKGROUND OF THE INVENTION

For purposes of this invention, the terms "can body" and "can" are used to represent hollow preformed containers including but not limited to cylindrical bodies.

There are known apparatus to provide continuous can printing; that is, apparatus for printing or coating the cylindrical body of a can without requiring intermittent movement of the rotatable can carrier.

There are many known can printing machine designs which require intermittent movement of a carrier mechanism that transports cans to and from a printing blanket cylinder. In such intermittent movement type of machines, the carrier mechanism remains in a fixed location during the actual printing operation although the can rotates about its own axis.

By contrast, the continuous can printing machines provide for continuous movement of the carrier in an arc about an axis removed from the can. In addition, the can rotates about its own axis during the actual printing operation. The major advantage of a continuous can printing machine is that it provides the capability for much larger capacity and for greater efficiency. Known types of continuous can printing machines are described in U.S. Pats. No. 2,936,701 (Stuchberry), No. 3,261,281 (Hartmeister) and No. 3,356,019 (Zurick).

It is of major importance in the continuous can printing machinery that the can support and the printing blanket be thrown out of contact with one another when a can is missing from the support or when a can is damaged. An empty support in contact with the printing blanket picks up ink on the surface of the support with the result that the next can placed on the support has ink applied to its inside surface. Among the reasons why it is desirable to avoid contact between damaged cans and the blanket is that a damaged can may injure the blanket.

Accordingly, it is a major purpose of this invention to provide a technique for assuring that a can support and printing blanket in continuous can printing machinery pass without contact under predetermined conditions such as a missing can or a damaged can.

Since one of the major purposes of improvements in this can printing art is to provide greater capacity and greater efficiency, it is a very important purpose of this invention to provide a rapidly operating mechanism for separating the support and printing blanket under predetermined conditions. The more rapidly the separating mechanism operates, the greater will be the maximum speed of the can printing machine.

The problem to which this invention is addressed exists not only when a legend is printed on a can, but also when a paint undercoat or a shellac overcoat is applied. Thus it should be understood herein that this invention applies to printing and coating generally and the term printing is used herein generically to refer to the application of a paint coat, shellac overcoat and the like as well as legend printing.

BRIEF DESCRIPTION OF THE INVENTION

In brief, this invention is employed in connection with a can carrier mechanism having a series of radial arms on each of which arm a mandrel is supported. Each mandrel has a shaft mounted within a bore on the respective carrier arm. The shaft extends forward from the bore within which it is supported. A rotatable outer sleeve on the forward extension provides a can support. This rotatable outer sleeve permits a can mounted thereon to rotate about the can axis, which rotation is important during printing.

This invention provides an eccentric sleeve around the portion of the shaft that is within the bore of the associated carrier arm. Rotation of the eccentric sleeve within the bore displaces the axis of the shaft and thus displaces the axis of the can support, in a direction that causes the can support to avoid contact with the print blanket during printing. A plate attached to the forward end of the eccentric sleeve has an arm extending radially out from the sleeve. At the end of this arm a cam follower is mounted. A proximity device senses the presence or absence of a can on the can support. The absence of a can causes the proximity device to generate a signal that operates on a fast acting solenoid operated air cylinder to move a trip cam into a camming position. In the camming position, the trip cam engages the cam follower causing the support arm for the cam follower and the eccentric sleeve to rotate. This rotation causes the can support to be displaced sufficiently so that it misses the print blanket cylinder during rotation of the carrier mechanism. Another arm connected to the eccentric sleeve is spring loaded in such a fashion that the eccentric sleeve is normally biased in a first rotational direction against a stop thereby establishing a print position. When the cam is extended into its trip position, the action of the cam in the cam follower rotates the eccentric sleeve through toggle so that the spring loaded arm biases the eccentric sleeve in a second rotational direction against a second stop thereby establishing a trip position. Because the trip and print positions are on either side of toggle, a reset cam is provided which operates on a reset cam follower that is mounted on an approximately radial arm connected to a plate attached to the rear end of the eccentric sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of the paint transfer mechanism for applying a coating to cans which are continuously rotated about a central axis.

FIG. 2 is an elevation view illustrating six successive can holding mandrels showing their relationship to a print roll and to the two cams that operate to cause the can support and mandrel to trip so as to avoid contact with the print roll when the can support is empty.

FIG. 3 is a view similar to that of FIG. 2 but on a larger scale and showing three successive mandrels to illustrate the relationship between the can carrying mandrel arrangement and the two trip cams.

FIG. 4 is a vertical cross-sectional view, in partial elevation, of the trip cams and associated mechanism showing their relationship to the can support and mandrel shown in elevation.

FIG. 5 is a cross-section view, in partial elevation, of the can carrying mandrel showing the relationship of the eccentric sleeve to the trip cam follower and to the reset cam follower.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The drawings all represent a single embodiment. FIG. 1 illustrates an ink applicator 12 which applies ink to the surface of gravure cylinder 14. The surface of a blanket cylinder 16 has a rubber type composition surface which picks up ink from the gravure cylinder 14. The gravure cylinder 14 and the blanket cylinder 16 both continuously rotate. The blanket cylinder 16 serves to transfer the pattern on the gravure cylinder 14 to the surface of the individual cans 18. The cans 18 are mounted along the periphery of a carrier 20. The carrier 20 continuously rotates about its central axis so that the cans 18 are sequentially brought into contact with the blanket 16. A doctor blade 22 assures that the cells of the gravure cylinder 14 are all filled. A trip cam 24 and reset cam 26 are shown in somewhat exaggerated size and spacing to illustrate their general location in the system.

FIG. 2 illustrates a series of six successive mandrels 30 all mounted on a clockwise rotating carrier 20. Each mandrel 30 has a substantially cylindrical can support 32. In FIG. 2, the end of this can support 32 is seen. The can support 32 projects forward from the plane of FIG. 2. The relationship between the can support 32 and the rest of the mandrel 30 can best be seen in FIG. 5. A cam follower 34 in the form of a rotatable roller is mounted at the outboard end of each mandrel 30.

In order to permit increased speed of operation two cams, a cam 24 and a cam 25, are employed. These two cams 24 and 25 are displaced from one another in a direction perpendicular to the plane of FIG. 2. FIG. 4 shows the spaced relation between cams 24 and 25 more clearly; cam 25 being shown behind cam 24. In FIG. 2, the front cam 24 is shown in its normal "print" position while the back cam 25 is shown in its trip position.

Successive cam followers 34 are alternately displaced in a direction perpendicular to the plane of FIG. 2 so that the cam 24 is associated with every even follower 34 and the cam 25 is associated with odd follower 34. This cam and cam follower arrangement may be seen a bit more clearly in FIG. 4.

A separate fast acting solenoid actuated air cylinder 36 is associated with each of the cams 24, 25. Each cam 24, 25 is mounted at an axis 42 which is approximately the center of gravity of the cam 24, 25 so that the amount of work that has to be done in moving the cam between its normal position to its trip position is minimum. The air cylinder 36 thus does not have to lift weight when changing the position of the cam 24 or 25 and has to expend energy simply to move the mass of the cam 24, 25 from one position to the other position. Accordingly, this minimum demand on the air cylinder 36 means that a minimum response time can be achieved and the overall system can operate at greater speed than otherwise would be the case. For simplicity, only one air cylinder 36 is shown in FIG. 4.

In FIG. 2, as well as in FIG. 3, the cam 24 is shown in its normal, non-trip position. In FIGS. 2 and 3 the mandrels 30 are marked A, B, C, D, E and F in order to distinguish between the mandrels and provide a correlation between the mandrels 30 shown in FIG. 2 and those shown in FIG. 3. The back cam 25 is associated with mandrels A, C and E. In operation, the cam 25 will be in its trip position, as shown, only for that period of time necessary to trip the mandrel 30 which has a missing can or an improperly placed can. In FIG. 2, the mandrel E is shown tripped and the cam 25 is shown ready to trip mandrel A. In this trip position, the cam follower 34 on the mandrel A will contact the cam surface of the cam 25 and cause the mandrel to move from the position shown for the mandrel A to the position shown for the mandrel E. Such movement results in a can support 32 movement radially inward toward the center of the carrier 20 so that the support 32 and whatever can 18, if any, mounted thereon will not contact the blanket cylinder 16.

As may best be seen in FIGS. 2 and 4, a proximity device 38 of a standard type is positioned on an arm 39. As each can carrier 32 is carried by the proximity device 38, the presence of a metal can causes the device to provide an output state change that confirms the presence of a can. Absence of a can is integrated by a logic network (not shown) as requiring the tripping of the associated mandrel, to which mandrel the logic circuit is synchronized. The proximity device 38 is positioned so that each can 18 passes close to but does not contact the device 38. Accordingly, the device 38 is supported in a slot 40 on the arm 39 to permit optimum positioning of the device 38. Furthermore the arm 39 is mounted on the cam shaft 41 by an adjustable clamp mechanism that permits rotating the arm 39 about the shaft 41 to permit adjusting the angular position of the device 38 with respect to the mandrel 30 at which can sensing occurs. Between the rotational adjustment of the arm 39 about the shaft 41 and the adjustment of the sensor 38 along the length of the arm 39, it is possible to select a can sensing position that provides enough time to permit the air cylinder to operate before the cam follower 34 hits the surface of the tripped cam 24 or 25.

In the embodiment shown, only one sensor 38 is employed. Thus the logic circuits have to be synchronized to the mandrel 30 involved so that the appropriate one of the two cams 24, 25 is tripped.

As shown in FIG. 4, the sensor 38 is positioned just above the edge of a can 45 when the can is properly loaded on the rotatable insulating support sleeve 43. In other words, the sensor 38 is in juxtaposition to a can adjacent the edge thereof when the can is properly mounted on the sleeve 43. The sleeve 43 is mounted for rotation rotating about the axis 44 of the can support shaft 46. Although the sleeve 43 is metal, the sensor senses the extra thickness of the metal can. Thus, a distinction is presented to the sensor 38 due to the presence or absence of a can. Thus if a can is so damaged that it can not or does not fit fully on the sleeve 43, such a can will not be sensed by the proximity sensor 38.

As best shown in FIG. 5, the mandrel shaft is an eccentric two part shaft. There is a can support shaft portion 46 and a main shaft portion 47. These two shaft portions 46, 47 are rigidly linked together by shaft flange 47a. The purpose of the offset between the axis 44 of can support shaft 46 and the axis 48 of the main portion 47 is to make possible a continuously rotating can carrier 20 as described in U.S. Pat. No. 3,356,019. As described therein, during printing, the main shaft 47 of the sleeve 43 is rotated about its own axis 48 through the action of a box cam 49 and coacting cam follower 50, that extends out from the back end of the main shaft 47. This rotation, during printing, of the main shaft 47 causes the can carrier 32 to move in an arc that is parallel to the circular periphery of the print blanket 16 so that there is contact between the can 18 and print blanket 16 for a sufficient period of time to ensure printing or coating of the entire can body without requiring intermittent operation of the can carrier mechanism 20 so that a continuous operating can carrier is provided.

As may perhaps best be seen in FIGS. 3 and 5, the main shaft portion 47 is mounted within an eccentric sleeve 52. The eccentric sleeve 52, in turn, is mounted within a bore 53 of carrier 20. Thus, it may be seen that if the eccentric sleeve 52 is rotated within the bore 53 of carrier 20, the shaft 46, 47 will be displaced relative to carrier 20. A front plate 56 and a back plate 57 are rigidly mounted to the eccentric sleeve 52. The front plate 56 includes an arm 58 to the end of which rotatable cam follower 34 is mounted. An arm 60 biased by spring 59 is connected by a pin 61 to the front plate 56. The pin 61 permits the arm 60 to rotate relative to the axis of the pin 61. The opposite end of arm 60 is supported in rotatable poppet 54. The eccentric sleeve 52 together with the front plate 56 and back plate 57 constitute a single rotatable unit by virtue of the fact that these plates 56, 57 are keyed or bolted to the eccentric sleeve 52. As a consequence, rotation of either one of these plates 56, 57 causes rotation of the sleeve 52 and of the other plate 57, 56. Such rotation is within the bore 53 of the carrier 20 within which the mandrel 30 is mounted.

When a cam 24, 25 is rotated into the trip position, the cam follower 34 that contacts the cammed surface causes the associated front plate 56 to rotate counter-clockwise (as seen in FIGS. 2 and 3). This movement rotates the eccentric sleeve 52 by an amount that displaces the shaft 46, 47 and thus the can support 32 in a counter-clockwise direction away from the blanket cylinder 16. Mandrel E in FIG. 2 represents such a tripped mandrel and the can support 32 can be seen as retracted or displaced inward toward the center of the carrier 20. The can support 32 when so tripped will follow its usual arc but displaced enough to miss the blanket 61.

From FIG. 3, it can be seen that the line of action of the spring-loaded arm 60 is such as to tend to push this eccentric unit (sleeve 52 and plates 56, 57) to rotate in a clockwise direction within the bore 53 when the mandrel is in the print position. An adjustable stop 64 is positioned on the carrier 20 so as to limit the amount of clockwise rotation of the eccentric sleeve 52 when in the print position. This adjustable stop 64 abuts against an extension 66 of the back plate 57. The stop 64 is adjustable so that the pressure between cans carried on the can support 32 and the blanket cylinder 16 can be adjusted.

When one of the trip cams 24, 25 causes the unit composed of the eccentric sleeve 52 and plates 56, 57 to rotate in a counter-clockwise direction so as to retract the can support 32 into the trip or non-printing position, the result is as illustrated by mandrel E in FIGS. 2 and 3. In this trip position, the spring-loaded arm 60 holds the eccentric unit 52, 56, 57 against a fixed stop 68 (see FIG. 3) on the carrier 20, thereby limiting the counter-clockwise rotation to that required to insure the can will miss the blanket cylinder 16. The extension 66 of the back plate 57 has one edge that contacts the adjustable stop 64 in the print position.

When a mandrel 30 has been cammed into the trip position, it is held in the trip position by a toggel action and must be cammed back into the print position after it has passed the print station and prior to the can loading station. A reset cam 70 and reset follower 71 (see FIG. 5) perform this function. The reset cam 70 is in a fixed position on the frame of the machine. When the mandrel 30 is in the print position, the cam follower 71 misses the reset cam 70. But when the mandrel 30 is in the trip position, the cam follower 71 is moved, because of its attachment to the back plate 57 that is affixed to the eccentric sleeve 52, to a position where rotation of the mandrel past the print position brings the cam follower 71 into contact with the cam 70. The cam 70 then forces the cam follower and the plate 57 and sleeve 52 to which it is mounted to rotate back through toggle to the normal print position. This reset action is positioned to occur prior to the loading station (not shown).