Ink station assembly for a can decorator

Abstract

An ink station assembly (10) for a can decorator, such as a beverage can decorator, is disclosed herein. The ink station assembly (10) comprises a plurality of mutually cooperating rolls (11, 11a-11i) that is arranged for receiving ink and for transferring the ink via the rolls (11, 11a-11i). Each of the rolls (11, 11a-11i) is axially rotatable about a respective roll axis. The plurality of rolls (11, 11a-11i) includes at least one oscillating roll (11a, 11b) arranged to oscillate along its roll axis. The ink station assembly (10) further comprises a drive system (30) that is arranged to rotate the rolls (11, 11a-11i) and oscillate the at least one oscillating roll (11a, 11b). The drive system (30) comprises a first mechanical transmission system arranged for rotating the rolls (11, 11a-11i) and a second mechanical transmission system arranged for oscillating the at least one oscillating roll (11a, 11b) independently of a rotation of the rolls (11, 11a-11i). The present invention further relates to a can decorator comprising such an ink station assembly (10), to a kit-of-parts for forming such an ink station assembly (10), to a method of upgrading an existing can decorator as well as to a method of operating the can decorator comprising such an ink station assembly (10).

Description

[0001] INK STATION ASSEMBLY FOR A CAN DECORATOR

[0002] The present invention relates to an ink station assembly for a can decorator, such as a beverage can decorator, and to a can decorator comprising such an ink station assembly. The present invention further relates to a kit-of-parts for forming such an ink station assembly, to a method of upgrading an existing can decorator, and to a method of operating the can decorator comprising such an ink station assembly.

[0003] Graphics and text are intricately printed on cans, particularly beverage cans, using high-speed industrial machines called decorators. These decorators employ various components to effectively transfer print designs onto the cylindrical surface of cans.

[0004] Typically, in a decorator, cans are fed onto a mandrel wheel or spindle disk, where they are drawn onto mandrels using vacuum. As the cans rotate with the mandrel wheel, they come into contact with printing blankets on a rotating blanket wheel. Ink is transferred from print plates on a print plate cylinder to these printing blankets, which then imprint the graphics and text onto the cans. An over-varnish unit further applies a protective layer to the printed designs before the cans are cured.

[0005] The Rutherford Decorator is an example of such a decorator and comprises a drum assembly with blanket segments, ink station assemblies with plate cylinder shaft assemblies for applying ink to the blanket segments, a main drive gear for synchronously rotating the plate cylinder shafts as the blanket segments are rotated past the ink station assemblies, and a mandrel wheel assembly for can rotation for transferring ink from the blanket segments onto the cans.

[0006] In can decoration, ink film thickness is to be consistent to ensure a clear and uniform image on the printed can. Inconsistencies can cause colour density variations and ghosting of the image. To address these issues, prior solutions have involved adding more rolls, changing roll diameters, and adding rider rolls or oscillating rolls. Some prior art ink station assemblies include oscillating rolls that axially move back and forth by means of a pivoting lever mechanism that cooperates with a cam. In some configurations, a discrete cam is used that is mounted directly on the oscillating roll shaft.

[0007] However, a drawback of these prior art decorators is that at operating speeds of over 1000 cans per minute, for example 2000 to 2200 cans per minute, a lot of wear occurs, for instance on parts such as bronze bushings. Furthermore, increasing the operating speed has been found to cause ink misting and excessive pollution and heat generation inside the ink station assembly. In previous attempts to partially address these limitations, a cooling system was introduced, including passages in the rolls for coolant flow therethrough. However, it has been found that this solution, when put into practice, leads to increased complexity and costs.

[0008] It is an object of the present invention, amongst other objects, to provide an improved ink station assembly wherein the aforesaid drawbacks are at least partially alleviated in an efficient manner.

[0009] Hereto, an ink station assembly for a can decorator, such as a beverage can decorator, is provided, wherein the assembly comprises: a plurality of mutually cooperating rolls that is arranged for receiving ink and for transferring the ink via the rolls, wherein each of the rolls is axially rotatable about a respective roll axis, wherein the plurality of rolls includes at least one oscillating roll arranged to oscillate along its roll axis; a drive system that is arranged to rotate the rolls and oscillate the at least one oscillating roll, wherein the drive system comprises a first mechanical transmission system arranged for rotating the rolls and a second mechanical transmission system arranged for oscillating the at least one oscillating roll independently of a rotation of the rolls.

[0010] By oscillating the one or more oscillating rolls independently of the axial rotation of the rolls, oscillation of the oscillating rolls at an oscillation speed that is not directly proportional to the rotation speed of the rolls is enabled. Therefore, the rotation speed of the rolls, which is related to the overall can decorating speed, can be increased without proportionally increasing the oscillation speed of the oscillating rolls. The present invention is based on the insight that the aforesaid disadvantageous effects like ink misting, pollution, wear and heat generation inside the ink station assembly are particularly caused by the oscillation of the oscillating rolls at high operating speeds, and that the aforesaid disadvantageous effects at high operating speeds can therefore be considerably reduced by not increasing the oscillation speed proportionally to the rotation speed. Moreover, by oscillating the one or more oscillating rolls independently of the rotation of the rolls, the oscillation speed can be controlled separately from the rotation speed, and the oscillation speed can be optimised such that one or more of the aforesaid issues are minimised. In prior art decorators, on the contrary, the oscillation speed of the oscillating rolls is proportional to the rotation speed of the rolls, as it is conventional in the art to increase the oscillation speed with the operating speed, as well as to drive the oscillation of the oscillating rolls via the same gear train that is used to drive the axial rotation of the rolls. Hence, the ink station assembly provided herein represents an improvement over the prior art. The mechanical transmission systems are preferably movable independently of, and / or controllable separately from, each other.

[0011] A preferred embodiment of the ink station assembly further comprises a motor, preferably an electric motor. The motor is arranged to drive the second mechanical transmission system independently of the first mechanical transmission system. Preferably, the ink station assembly further comprises a frequency controller arranged for controlling the motor to selectively set an oscillation speed of the one or more oscillating rolls. By means of the motor and the frequency controller arranged as described herein, the oscillation speed can be conveniently set independently of the rotation speed.

[0012] The ink station assembly may comprise a motor support member arranged for supporting a motor to drive the second mechanical transmission system. The motor support member is preferably fixed to a frame of the ink station assembly. This way, the motor can be efficiently supported close to the second mechanical transmission system and / or the one or more oscillating rolls.

[0013] According to a further preferred embodiment of the ink station assembly, the second mechanical transmission system comprises a cam follower member coupled to the at least one oscillating roll, and a cam member engaged with the cam follower member, wherein the second mechanical transmission system is arranged for moving the cam member, wherein the cam follower member is arranged to transmit movement of the cam member to oscillation of the oscillating roll along its roll axis. E.g., each oscillating roll may have a cam follower coupled thereto, and the cam member may be engaged with one or more, or each, of the cam followers.

[0014] The cam member may be provided with a circumferential groove forming a continuous undulating cam profile engaged with the cam follower member. Further, the cam follower member may be arranged pivotable relative to a frame of the ink station assembly about a pivot axis, wherein the cam follower member is arranged to pivot about the pivot axis during movement of the cam member. The pivot axis is preferably skew with the roll axis of the oscillating roll. That is, the pivot axis is neither intersection, nor parallel to, the one or more roll axes. With any one or more of these features, the movement of the cam member can be efficiently transmitted to oscillation of the oscillating roll.

[0015] Preferably, the cam member is axially rotatable, wherein the second mechanical transmission system is arranged for rotating the cam member, wherein the cam follower member is arranged to transmit rotation of the cam member to oscillation of the oscillating roll along its roll axis. Although the use of a cam mechanism to oscillate the oscillating rolls is known in the art, the movement of the cam member is conventionally driven via the same gear train that is used to drive the axial rotation of the rolls. By, instead, driving the movement of the cam member independently of the rotation of the rolls in accordance with the present disclosure, an improved ink station assembly can be provided, as described above.

[0016] According to a further preferred embodiment of the ink station assembly, the cam member comprises a gear part. The gear part may enable the transmission of torque to the cam member for rotating the cam member. Preferably, the second mechanical transmission system is arranged to transmit torque from the motor to the gear part, for example by means of a belt drive.

[0017] The cam member may be coaxially arranged around a shaft. Preferably, the cam member is axially rotatable relative to the shaft. The cam member may be connected to the shaft by a bearing coupling, preferably a fixed-bearing coupling. In an alternative embodiment, the second mechanical transmission system may be arranged for rotating the shaft. In this case, it is preferred if the cam member is fixedly coupled to the shaft.

[0018] The shaft around which the cam member is arranged, may be an axially rotatable drive shaft. The shaft may have the function of transmitting rotation, for example by accommodating a gear mounted thereon. The shaft may be arranged to be rotationally driven by the first mechanical transmission system. In said alternative embodiment, the gear on the shaft may be axially rotatable relative to the shaft, for example by being connected thereto by a bearing coupling, wherein the gear is arranged to be rotationally driven by the first mechanical transmission system.

[0019] As the cam member of the second mechanical transmission system is axially rotatable relative to the member that is rotationally driven by the first mechanical transmission system, which may be either the shaft around which the cam member is arranged or the gear thereon as such, oscillation of the one or more oscillating rolls independently of a rotation of the rolls is enabled. It is to be appreciated that on the basis of the present disclosure, alternative solutions to oscillate the one or more oscillating rolls independently of a rotation of the rolls can be envisaged. Yet, the above solution in particular has the advantage that existing ink station assemblies in which a cam mechanism is used to oscillate the oscillating rolls, can be efficiently adapted such that the oscillating rolls can be oscillated independently of a rotation of the rolls.

[0020] The plurality of rolls may include two or more oscillating rolls. E.g., each oscillating roll may have a respective cam follower coupled thereto. Alternatively, said cam follower member may be coupled to some or each of the oscillating rolls. Preferably, the cam follower member is coupled to the two or more oscillating rolls at opposite sides of a plane containing the pivot axis and extending parallel to one or each of the respective roll axes of the oscillating rolls. This way, the oscillating rolls are translated in mutually opposite directions that alternate during each oscillation. That is, the oscillations of the respective oscillating rolls are preferably counterphase.

[0021] Preferably, the cam follower member is coupled to the two or more oscillating rolls equidistantly from the pivot axis. This way, it can be ensured that the amplitudes of the respective oscillations are the same.

[0022] The ink station assembly may further comprise an axially rotatable plate cylinder shaft for mounting a print plate cylinder, including a print plate, thereon, wherein the plurality of mutually cooperating rolls is further arranged for applying the ink to the print plate of a print plate cylinder mounted on the plate cylinder shaft.

[0023] The ink station assembly may further comprise an ink supply arranged for supplying ink to the plurality of rolls.

[0024] According to a further aspect, a kit-of-parts for forming part of an ink station assembly as described herein is provided, the kit-of-parts comprising at least the shaft and the cam member. Preferably, the shaft is a shaft as described above and / or the cam member is a cam member as described above. In particular, the cam member may be connectable to the shaft by a bearing coupling, preferably a fixed-bearing coupling. It is further preferred if the shaft is an axially rotatable drive shaft.

[0025] Further, a cam member for forming an ink station assembly as described herein is provided, wherein the cam member is configured to be coaxially arranged around a shaft and to be axially rotatable relative to the shaft, the cam member comprising a gear part for receiving an input torque to axially rotate the cam member. Preferably, the cam member is a cam member as described above. In particular, the cam member is provided with a circumferential groove forming a continuous undulating cam profile.

[0026] According to a further aspect, a method of upgrading an existing can decorator is provided, the decorator comprising a plurality of ink station assemblies, each comprising a plurality of mutually cooperating rolls that is arranged for receiving ink and for transferring the ink via the rolls, wherein each of the rolls is axially rotatable about a respective roll axis, wherein the plurality of rolls includes at least one oscillating roll arranged to oscillate along its roll axis. Each ink station assembly further comprises a drive system that is arranged to rotate the rolls and oscillate the at least one oscillating roll, wherein the method comprises the step of adapting the drive system of at least one of the ink station assemblies of the existing can decorator such that the at least one ink station assembly is an ink station assembly as described herein.

[0027] The drive system of the at least one ink station assembly of the existing can decorator may comprise an axially rotatable drive shaft, a cam follower member coupled to the at least one oscillating roll, and a cam member coaxially arranged around and rotationally fixed to the axially rotatable drive shaft and engaged with the cam follower member, wherein the cam follower member is arranged to transmit movement of the cam member to oscillation of the oscillating roll along its roll axis.

[0028] The method preferably comprises the steps of providing a kit-of-parts as described above and replacing the shaft and the cam member of the drive system with the shaft and the cam member of the kit-of-parts such that the cam member of the kit-of-parts is coaxially arranged around, and is axially rotatable relative to, the shaft of the kit-of-parts.

[0029] Further provided is a can decorator, comprising one or more ink station assemblies, each comprising an axially rotatable plate cylinder shaft and arranged for supplying ink to a print plate cylinder mounted on the plate cylinder shaft, wherein at least one of the ink station assemblies is an ink station assembly as described herein.

[0030] A preferred embodiment of the can decorator further comprises: a drum assembly circumferentially provided with a plurality of blanket segments for receiving ink, wherein each ink station assembly is arranged for supplying ink to the plurality of blanket segments via the print plate cylinder mounted on the plate cylinder shaft, wherein the drum assembly is rotatably arranged for rotating the plurality of blanket segments past the plurality of ink station assemblies to supply ink to the plurality of blanket segments; an infeed device arranged for feeding cans into the decorator; a mandrel wheel assembly arranged for receiving the cans from the infeed device, for holding the cans by means of vacuum, and for rotating the held cans from the infeed device to the drum assembly to apply the ink from the blanket segments to the cans.

[0031] Further, a method of operating a can decorator as described above is provided, wherein the method comprises the steps of selecting an operating speed to which a rotation speed of the rolls of the ink station assemblies is directly proportional, selectively setting an oscillation speed of the one or more oscillating rolls, operating the can decorator at the selected operating speed by rotating the rolls at the rotation speed that corresponds to the selected operating speed and, simultaneously with the rotation of the rolls, oscillating the oscillating rolls of the ink station assemblies at the set oscillation speed.

[0032] The operating speed is preferably higher than 1000 cans per minute, preferably 2000 or more cans per minute, for example up to and including about 2200 cans per minute.

[0033] In the following, a preferred embodiment of the present invention is illustrated with reference to the accompanying drawings, wherein:

[0034] Figure 1 schematically represents a beverage can decorator known in the art;

[0035] Figure 2 represents a sectional side view of a known plate cylinder shaft assembly;

[0036] Figures 3 and 4 represent different views of a known ink station assembly;

[0037] Figures 5-8 represent an ink station assembly according to the present disclosure;

[0038] Figure 9 represents a cam member of the assembly shown in Figures 5-8.

[0039] In Figure 1, a beverage can decorator 100 of the Rutherford-type is schematically shown. The decorator 100 comprises an infeed conveyor 101 for feeding undecorated beverage cans 102 into the decorator 100 and a rotating mandrel wheel assembly 103 for receiving the cans 102 from the infeed conveyor 101. The mandrel wheel assembly 103 sucks the cans 102 onto mandrels along its circumference by means of vacuum and is mounted onto a rotating horizontal drive shaft 104 for rotating the held cans 102 from the infeed conveyor 101 to a rotating drum assembly 105 of the decorator 100.

[0040] The drum assembly 105 is circumferentially provided with a plurality of blanket segments 106 for receiving ink to be applied to the cans 102. Hereto, the decorator 100 further comprises a plurality of ink station assemblies 10’ positioned around the drum assembly 105, wherein each ink station 10’ is configured for supplying ink to the blanket segments 106. In each ink station assembly 10’, ink from an ink container at the top of the ink station 10’ is applied to a printing plate cylinder via one or more ceramic and polyurethane or rubber rolls 11. The blanket segments 106 are rotated past the ink station assemblies 10’ to supply the ink to the blanket segments 106 via the printing plate cylinders. The ink stations 10’ are each configured for supplying a different colour of ink in a respective image pattern to the blanket segments 106. Combined, these image patterns form the multicolour image to be applied onto the cans 102. That is, e.g., for a can decoration with eight colours, eight ink stations are used with eight different printing plates. Likewise, for a can decoration with four colours, four ink stations are used with four different printing plates. The decorator 100 shown in Figure 1 comprises six ink stations 10. Where the undecorated cans 102, rotated by the mandrel wheel assembly 103, meet the blanket segments 106, the cans 102 are brought into engagement with the blanket segments 106 such that the multicolour ink image on each blanket segment 106 is unrolled onto a respective can 102. That is, the entire image on a blanket segment 106 is unrolled onto a single can 102.

[0041] After ink is applied onto a can 102, a layer of varnish may be applied on the printed image in an over- varnish unit 109. Decorated and varnished cans 102 are transferred from the mandrels of the mandrel wheel assembly 103 via a transfer unit 110 to horizontal pins 111 carried by a chain-type conveyor 112, which carries the cans 102 through a curing oven (not shown).

[0042] As the blanket segments 106 are rotated past the ink station assemblies 10’, the printing plate cylinders are rotated to unroll the ink image from the plate cylinders onto the blanket segments 106. Hereto, each plate cylinder is mounted on an axially rotated plate cylinder shaft of the ink station assembly 10. In Figure 2, such a plate cylinder shaft assembly 1 is shown in longitudinal section. The plate cylinder shaft assembly 1 comprises the plate cylinder shaft 2, on which the print plate cylinder 3 is mounted, and a helical gear member 4 that is keyed to the plate cylinder shaft 2. The decorator 100 comprises a helical bull gear that simultaneously engages with the helical gear members 4 of the different plate cylinder shaft assemblies 1 around the drum assembly 105 for synchronously rotating the plate cylinder shafts 2 around their respective longitudinal axes A. The bull gear in such decorators is often about 1.5 metre in diameter. Each shaft 2 is rotatably mounted in two frame plates 5 via roller bearings 6.

[0043] The process of printing beverage cans requires precise mutual alignment of the different image patterns to ensure quality of the printed image. Circumferential registration is the process of angularly adjusting the print plate cylinder 3 about the main axis A. At a mounting end plate 7, wherein the print plate cylinder 3 is mounted on the shaft 2, the print plate cylinder 3 can be manually adjusted relative to the shaft 2.

[0044] In Figure 3, the ink station assembly 10’ is illustrated, wherein a number of known components of the assembly 10’ are not shown for simplicity. The assembly 10’ comprises three frame plates 5, in two of which the plate cylinder shaft 2 is mounted through mounting holes 50, and a plurality of axially rotatable rolls 11 that includes a supply roll 1 li, a ductor roll 1 Ih, three transfer rolls 1 le, 1 If, 11g, two oscillating rolls 1 la, 1 lb, and two form rolls 11c, l id, wherein the rolls 11 mutually cooperate to apply ink to the print plate of the print plate cylinder 3 mounted on the plate cylinder shaft 2. The oscillating roll Ila, 11b oscillate in the directions indicated by the double-headed arrow. The rolls 11 are rotated by means of a gear train 30 which, in Figure 3, is shown only partially.

[0045] Figure 4 represents a rear view of the ink station assembly 10’ and shows the gear train 30 for transmitting rotation to the rolls 11. The shown gear train 30 includes a gear 31 fixedly coupled to the plate cylinder shaft assembly 1 rotationally driven by the bull gear (not shown), a first idler gear 32, two gears 33, 34 for rotating the respective oscillating rolls Ila, 11b, second and third idler gears 35, 36, a gear 37 for rotating one of the transfer rolls 11g, an uppermost gear 39 for rotating the supply roll 1 li, and an intermediate pair of coupled, differently sized gears 38a, 38b. The larger gear 38a has been made transparent in Figure 4 to reveal the smaller gear 38b which engages the uppermost gear 39.

[0046] Referring again to Figure 3, the gear train 30 also oscillates the oscillating rolls Ila, 11b, as described in the following. To the shaft 41’ on which the intermediate pair of gears 38a, 38b is coupled, a cam member 42’ is fixedly coupled, for example by means of a keyed joint. The cam member 42’ is provided with a circumferential groove 43 forming a continuous undulating cam profile engaged with a cam follower member 44. Specifically, the cam follower member 44 comprises a Y-shaped arm and a cam follower provided on one end of the arm and fittingly arranged in the circumferential groove or cam 43 of the cam member 42. Rotation of the cam member 42’ causes the arm-like cam follower member 44 to pivot about a hinge 45 fixed to one of the frame plates 5. Regarding the arm-like cam follower member 44, it can be seen that on either side of the hinge 45, at the same distance, the other two ends of the Y-shaped arm of the cam follower member 44 are respectively coupled to the oscillating rolls Ila, 11b at respective attachment points via bearings. This way, when the cam member 42’ rotates, the oscillating rolls 1 la, 1 lb, in particular their respective shafts on which the ceramic roller part of the rolls Ila, 11b are arranged, make a counterphase oscillating movement, i.e., an oscillating movement in the opposite direction of each other. Thus, by rotating, the cam member 42’ provides the oscillating movement. The shafts of the oscillating rolls Ila, 1 lb are each rotationally driven by gears 33, 34 as detailed above. That is, these gears 33, 34 only function to provide the rotating movement of the oscillating rolls Ila, 11b. As also detailed above, the shaft 41’ on which the cam member 42’ is fixed is rotationally driven by the same gear train 30 that drives rotation of the oscillating rolls I la, 11b.

[0047] In Figures 5-8, an ink station assembly 10 according to the present disclosure is shown. Figures 5 and 6 represent different isometric views of the ink station assembly 10 and Figure 7 represents a side view of the ink station assembly 10 while, in Figure 8, the ink station assembly 10 is shown in longitudinal section. The cam member 42’ of the ink station assembly 10’ of the existing decorator 100 can be replaced in accordance with the present disclosure by the cam member 42 shown in Figure 8, as described in the following.

[0048] Next to the cam 43 of the cam member 42 shown in Figures 5-9, and spaced therefrom along the cam axis C, the cam member 42 is provided with a gear part 46. The cam member 42 is equipped with a pair of bearings 47, one at each end, by means of which the cam member 42 is arranged on its shaft 41, such that the cam member 42 can rotate on the bearings 47 relative to its shaft 41. By means of an electric motor 60 with a frequency controller, and via a drive belt 48 looped over the gear part 46 of the cam member 42, the rotation speed of the cam member 42, and therefore the oscillation speed of the oscillating rolls I la, 11b, can be selectively set independently of the operating speed of the can decorator 100.

[0049] In an alternative embodiment (not shown), instead of the cam member 42, the intermediate pair of gears 38a, 38b may be rotatably arranged on the shaft 41 by bearings. In this case, the cam member 42 may remain fixedly coupled to its shaft 41. It is then preferred if these gears 38a, 38b are coupled to each other for rotating synchronously. The motor 60 may then drive rotation of the cam member 62 via the shaft 41 instead of the gear part 46, such that the gear part 46 can be omitted. Thereto, a separate gear may be mounted on the shaft 41 with, e.g., a clamping bush or other coupling, such that said drive belt 48 can be looped over this separate gear.

[0050] In both embodiments, the shaft 41 on which the cam member 42 is arranged, keeps its function of accommodating the intermediate pair of gears 38a, 38b thereon which, as illustrated in Figure 4, can continue to transmit rotation to the uppermost gear 39 of the gear train 30.

[0051] That is, as shown in Figure 8 which represents a longitudinal section in a plane cutting through the cam shaft 41 and the shaft of the lower oscillating roller Ila, the cam shaft 41 is provided with four bearings, i.e., one existing pair of roller bearings 8 via which the shaft 41 is rotatably mounted in two frame plates 5, and one additional pair of roller bearings 47 that is installed in the cam member 42 and by which the cam member 42 is rotatably connected to the shaft 41. The shaft 41’ of the conventional ink station assembly 10’ only has the outer bearings 8 while the cam member 42’, without bearings, is keyed to the shaft 41’. By, instead, providing the cam member 42 and its shaft 41 with the additional bearings 47, the cam member 42 can be rotated in a controlled manner. In particular, the rotation speed of the cam member 42 can be selectively controlled, for instance independently of the rotation speed of the rolls 11. Thereto, a motor support 61 is fixed to one of the frame plates 5, such that the electric motor 60 can be arranged thereon. Like the cam member 42, the output shaft of the electric motor 60 is equipped with a gear part 62. The respective gear parts 46, 62 and the drive belt 48 are arranged to transmit torque from the motor 60 to the cam member 42, while the frequency controller enables an operator to rotate the cam member 42, and thereby oscillate the oscillating rolls 1 la, 1 lb, at a desired speed irrespective of the operating speed of the decorator 100. That is, the operator can control the electric motor 60 to control the rotation of the cam member 42 such that the oscillating rolls I la, 11b oscillate at the desired speed.

[0052] The inventor has namely found that in the conventional ink station assembly 10’, the oscillating movement of the shafts and ceramic rollers of the decorator 100 operating at high speed causes excessive ink pollution and results in wear and high temperatures. The inventor has additionally found how to enable the operator to selectively control the oscillation speed independently of the operating speed, and that the operator can thereby set the desired oscillation speed irrespective of the operating speed, for example by means of an electric motor with a frequency controller as described above. As a result, at high operating speeds, less wear, ink pollution and heat generation occur in the ink station assembly 10 according to the present disclosure, in comparison with the conventional ink station assembly 10’.

[0053] The drawings and the above description serve to illustrate specific embodiments of the invention and do not limit the scope of protection defined by the appended claims.

Claims

CLAIMS1. An ink station assembly for a can decorator, such as a beverage can decorator, the assembly comprising:- a plurality of mutually cooperating rolls that is arranged for receiving ink and for transferring the ink via the rolls, wherein each of the rolls is axially rotatable about a respective roll axis, wherein the plurality of rolls includes at least one oscillating roll arranged to oscillate along its roll axis;- a drive system that is arranged to rotate the rolls and oscillate the at least one oscillating roll, wherein the drive system comprises a first mechanical transmission system arranged for rotating the rolls and a second mechanical transmission system arranged for oscillating the at least one oscillating roll independently of a rotation of the rolls.

2. Ink station assembly according to claim 1, comprising an electric motor arranged to drive the second mechanical transmission system independently of the first mechanical transmission system.

3. Ink station assembly according to claim 2, comprising a frequency controller arranged for controlling the motor to selectively set an oscillation speed of the at least one oscillating roll.

4. Ink station assembly according to claim 1, 2 or 3, wherein the second mechanical transmission system comprises a cam follower member coupled to the at least one oscillating roll, and a cam member engaged with the cam follower member, wherein the second mechanical transmission system is arranged for moving the cam member, wherein the cam follower member is arranged to transmit movement of the cam member to oscillation of the oscillating roll along its roll axis.

5. Ink station assembly according to claim 4, wherein the cam member is axially rotatable, wherein the second mechanical transmission system is arranged for rotating the cam member, wherein the cam follower member is arranged to transmit rotation of the cam member to oscillation of the oscillating roll along its roll axis.

6. Ink station assembly according to at least claims 2 and 5, wherein the cam member comprises a gear part, wherein the second mechanical transmission system is arranged to transmit torque from the motor to the gear part.

7. Ink station assembly according to claim 5 or 6, further comprising an axially rotatable drive shaft arranged to be rotationally driven by the first mechanical transmission system, wherein the cam member is coaxially arranged around the axially rotatable drive shaft and is axially rotatable relative to the drive shaft.

8. Ink station assembly according to claim 7, wherein the cam member is connected to the axially rotatable drive shaft by a bearing coupling, preferably a fixed-bearing coupling.

9. Ink station assembly according to any of the preceding claims 4 to 8, wherein the cam member is provided with a circumferential groove forming a continuous undulating cam profile engaged with the cam follower member.

10. Ink station assembly according to any of the preceding claims 4 to 9, wherein the cam follower member is arranged pivotable relative to a frame of the ink station assembly about a pivot axis that is skew with the roll axis of the oscillating roll, wherein the cam follower member is arranged to pivot about the pivot axis upon movement of the cam member.

11. Ink station assembly according to any of the preceding claims 4 to 10, wherein the plurality of rolls includes at least two oscillating rolls, wherein the cam follower member is coupled to the at least two oscillating rolls.

12. Ink station assembly according to claims 10 and 11, wherein the cam follower member is coupled to the at least two oscillating rolls at opposite sides of a plane containing the pivot axis and extending parallel to one or each of the respective roll axes of the oscillating rolls.

13. Ink station assembly according to any of the preceding claims, comprising a motor support member fixed to a frame of the ink station assembly and arranged for supporting a motor to drive the second mechanical transmission system.

14. A kit-of-parts for forming part of an ink station assembly according to at least claim 7, the kit-of-parts comprising at least the drive shaft and the cam member.

15. A method of upgrading an existing can decorator, the decorator comprising a plurality of ink station assemblies, each comprising:- a plurality of mutually cooperating rolls that is arranged for receiving ink and for transferring the ink via the rolls, wherein each of the rolls is axially rotatable about a14 respective roll axis, wherein the plurality of rolls includes at least one oscillating roll arranged to oscillate along its roll axis;- a drive system that is arranged to rotate the rolls and oscillate the at least one oscillating roll, wherein the method comprises the step of adapting the drive system of at least one of the ink station assemblies of the existing can decorator such that the at least one ink station assembly is an ink station assembly according to any of the preceding claims 1-13.

16. Method according to claim 15, wherein the drive system of the at least one ink station assembly of the existing can decorator comprises an axially rotatable drive shaft, a cam follower member coupled to the at least one oscillating roll, and a cam member coaxially arranged around and rotationally fixed to the axially rotatable drive shaft and engaged with the cam follower member, wherein the cam follower member is arranged to transmit movement of the cam member to oscillation of the oscillating roll along its roll axis, wherein the method comprises the steps of providing a kit-of-parts according to claim 14 and replacing the drive shaft and the cam member of the drive system with the drive shaft and the cam member of the kit-of-parts such that the cam member of the kit-of-parts is coaxially arranged around, and is axially rotatable relative to, the drive shaft of the kit-of-parts.

17. A can decorator, comprising a plurality of ink station assemblies, each comprising an axially rotatable plate cylinder shaft and arranged for supplying ink to a print plate cylinder mounted on the plate cylinder shaft, wherein at least one of the ink station assemblies is an ink station assembly according to any of the preceding claims 1-13.

18. Can decorator according to claim 17, further comprising:- a drum assembly circumferentially provided with a plurality of blanket segments for receiving ink, wherein each ink station assembly is arranged for supplying ink to the plurality of blanket segments via the print plate cylinder mounted on the plate cylinder shaft, wherein the drum assembly is rotatably arranged for rotating the plurality of blanket segments past the plurality of ink station assemblies to supply ink to the plurality of blanket segments;- an infeed device arranged for feeding cans into the decorator;- a mandrel wheel assembly arranged for receiving the cans from the infeed device, for holding the cans by means of vacuum, and for rotating the held cans from the infeed device to the drum assembly to apply the ink from the blanket segments to the cans.

19. A method of operating a can decorator according to claim 17 or 18, wherein the method comprises the steps of:- selecting an operating speed to which a rotation speed of the rolls of the ink station assemblies is directly proportional; - selectively setting an oscillation speed of the one or more oscillating rolls;- operating the can decorator at the selected operating speed by rotating the rolls at the rotation speed that corresponds to the selected operating speed;- oscillating the oscillating rolls of the ink station assemblies at the set oscillation speed simultaneously with the rotation of the rolls.

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