Patent Grant
7036428
The present invention relates generally to printing machines, and more particularly, to printing machines adapted for printing cylindrical surfaces.
Gravure rotary printing machines are known for printing cylindrical surfaces. Such printing machines typically have a solid metal printing cylinder with an etched outer surface that receives ink and transfers an ink pattern, as determined by the etching, to a silicon coated transfer cylinder, which in turn applies the image to the outer surface of a rotatably supported cylindrical item or the like to be printed. For supplying ink to the gravure cylinder, ink is continuously pumped from an ink supply to a doctor assembly which applies ink to the etched surface of the gravure cylinder, while doctoring excessive ink for return to the ink supply and ultimate recirculation to the doctor assembly. By reason of the required recirculation of the ink during a printing operation, the ink continuously evaporates, causing the escape of noxious fumes into the environment potentially harmful to workers. Due to such evaporation, the viscosity of the ink in the ink supply must be monitored and solvent must be periodically added to the ink to maintain proper viscosity. The ink recirculation also can be messy, sometimes causing ink splattering within the work environment. Since the etched gravure cylinder is made of solid metal, it further is expensive and significantly adds to the cost of the printing machine.
It is the object of the present invention to provide a machine for printing cylindrical items in which the ink supply is protectively enclosed from the environment of the workers and does not release harmful fumes.
Another object is to provide a printing machine as characterized which eliminates the need for monitoring ink viscosity or the addition of solvents to the printing ink during operation,
A further object is to provide a printing machine of the foregoing type that is economical in construction and more efficient in operation. A related object to provide such a printing machine which eliminates the necessity for costly gravure printing cylinders and ink transfer pumps.
Still another object is to provide a printing module for a printing machine of the above kind that enables easy field modification of conventional gravure printing machines for operation in accordance with the invention.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:
While the invention is susceptible of various modifications and alternative constructions, a certain illustrated embodiment thereof has been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions and equivalents falling within the spirit and scope of the invention.
Referring now more particularly to the drawings, there is shown an illustrative printing machine 10 adapted for applying printed images onto cylindrical surfaces, such as the outer surface of a cylindrical item 11. The illustrated machine 10 includes a printing module 12 for applying an ink image to a transfer cylinder 14 having an outer surface, preferably made of silicon, which receives inked images from the printing module 12 for transfer to the outer surface of the cylindrical item 11.
In accordance with the invention, the printing module includes a contained ink supply system for supplying ink to a continuously moving flexible band which, in turn, transfers ink images to the transfer cylinder. The printing module 12 in this case has a multi-part housing 15 comprising central housing body members 18, 19 and front and rear side plates 20, 21 bolted to the body members 18, 19 for tying the body members 18, 19 into a unitary housing structure. The illustrated printing module 12 has a cover plate 22 secured about the front side plate 20 for further enclosing the front side of the housing 15.
In carrying out the invention, the module 12 has an endless ink receiving and transfer band or belt 25 disposed for movement about a pair of laterally spaced pulleys, which in this case comprises a drive pulley or sprocket 28 and a take-up pulley 29. The pulleys 28, 29 are supported by the housing 15 in laterally spaced relation so that the band 25 defines semi-circular end sections 25a, 25b and substantially flat horizontal upper and lower sections 25c, 25d. The central housing body member 18 in this instance is cradle shaped having an upstanding side 18a, disposed on the left-hand side thereof as viewed in
The band 25 is preferably made of metal, such as stainless steel, and has a laser finished joint so as to provide a continuous smooth outer surface. The band 25 has an etched ink receiving outer area, preferably formed by laser etching, for receiving a predetermined ink image for transfer to the transfer cylinder 14 as an incident to movement of the endless band 25 about the pulleys 28, 29.
For rotatably driving the drive pulley 28, the drive pulley 28 is mounted on a drive shaft 30, which may be driven in a conventional manner from the main drive of the printing machine 10. The drive pulley 28 in this case has a drive key 31 press fit within a central bore thereof for receipt within a keyway in the drive shaft 30.
To facilitate positive driving movement of the band 25 as an incident to rotary movement of the drive pulley 28, the drive pulley 28 has a plurality of circumferentially spaced sprockets, which in this case are in the form of balls 32 adjacent opposite axial ends thereof protruding at circumferentially spaced points from an outer surface of the drive pulley 28. The balls 32 of the drive pulley 28 sequentially engage respective apertures 34 in opposite sides of the band 25 to effect movement of the band about the pulleys 28, 29 when the drive pulley 28 is driven.
In keeping with the invention, in order to permit removal and replacement of the printing module 12 on the drive shaft 30 and to facilitate tensioning and untensioning of the band 25, the drive pulley 28 is supported on the drive shaft 30 by a concentric double bearing arrangement. First, the drive shaft 30 is supported by a pair of bearing sets 34 each supported within respective stationery sleeve or hub 38 fixed to a respective housing plate 20, 21 by bolts 39. The bearing sets 34 are axially retained by an internal shoulder of the respective hub 38 and a snap ring 40 fixed within the hub 38. Secondly, relatively larger bearing sets 41 support the drive pulley 28 for rotation relative to the fixed bearing hubs 38. The second bearing sets 41 each are axially retained by a respective shoulder in the drive pulley 28 and an outwardly extending radial lip 38a of the bearing hub 38. To retain the module 12 in position on the drive shaft 30, a retaining bolt 42 having a head overlying the forward inner bearing set 34 is screwed into the front axial end of the drive shaft 30. The take-up pulley 29 in this case is supported by bearings 44 for rotation about a stationery shaft 45 fixed between the forward and rearward housing plates 20, 21.
In order to selectively tension the band 25, the take-up pulley 29 is laterally positionable relative to the drive pulley 28. To this end, opposite axial ends of the take-up pulley shaft 45 are formed with horizontal flats 48, which are positionable within horizontally extending rectangular slots 48a in the front and rear side plates 20, 21. Compression springs 49 are disposed within pockets 50 of the side plates 20, 21, each being interposed between a blind side of the pocket 50 and a set screw 51 threadedly extending horizontally through a respective axial end of take-up pulley shaft 45. For establishing the desired tension on the ink transfer band 25, the set screws 51 can be selectively adjusted. Advancement of the set screws 51 into and through the take-up pulley shaft 45 against the compression springs 49 increases the opposite biasing force on the shaft 45 and the resulting tension on the band 25. Opposite rotation of the set screws 51, i.e. in a retracting direction, reduces the compression of the springs 49 and reduces tension force on the band 25.
To overcome the force of the compression springs 49 on the band in order to permit band removal and replacement, a crank mechanism 55 is provided. The crank mechanism 55 includes a crank shaft 56 rotatably supported between the front and rear side plates 20,21 at a location between the pulleys 28, 29. The crankshaft 56 carries eccentrically mounted cams 58 at its opposite ends, which each are disposed within a respective circular camming receiving aperture in one end of an elongated cam plate 60, the other end of which is formed with an elongated take-up pulley shaft receiving slot. Cam plate retaining washers 61 and screws 62 retain the cam plates 60 on the take-up pulley shaft, while permitting relative lateral movement.
Rotation of the crank shaft 56 in a clockwise direction, as viewed in
In carrying out a further feature of the invention, for supplying ink to the moving band 25, an inverted ink supply cup 70 is positioned on the upper horizontal section 25c of the band 25 at a location between the drive and take-up pulleys 28, 29. The ink cup 70 may be of a conventional type used in pad printing machines, which comprises a molded plastic reservoir body with an open lower end and a separate annular doctor blade 71 bonded in the lower end of the body around its opening. The open bottom of the cup 70 provides free access of ink to the upper horizontal surface 25c of the band 25 and the doctor blade 71 defines a sealing and doctoring lower end. Hence, as the band 25 is moved past the underside of the ink cup 70, ink is supplied to the engraved image on the band and is simultaneously doctored by the blade 71.
For maintaining the ink cup 70 in position on the moving band 25, a cup hold-down mechanism is provided which includes a pair of arms 74 pivotally supported on an upstanding upper portion of the central housing body 18. Outer free ends of the arms 74 pivotally engage diametrically opposed front and rear sides of a lower ink cup flange 70a. For biasing the arms 74 in a cup hold position, a spring 75 is connected between opposite rearward ends of the arms 74 and an upstanding bracket 76 supported by the central housing body member 18.
For supporting the underside of the band 25 at the location of the ink cup 70, a bearing plate 80 is fixed to the central housing body member 19 immediately below the upper horizontal section 25c of the band 25. To facilitate relative movement between the band 25 over the bearing plate 80 and to facilitate the sealing contact between the ink cup 70 on the moving band 25, the bearing plate 80 preferably is formed of a laminate plastic material, or a metal plate with an upper plastic, preferably teflon, laminate or coating.
To permit removal and replacement of the ink cup 70, the ink cup hold-down arms 74 are pivotable in a counter-clockwise direction as depicted in
In operation of the printing machine 10, it can be seen that with the ink cup 70 in its hold-down position on the horizontal section 25c of the moving band 25, ink will be doctored onto the etching on the band and the ink image will be transferred to the transfer cylinder 14, and in turn, onto the cylindrical item 11. The ink supply is protectively contained and enclosed from the environment of workers around the machine during the printing operation. Likewise, no evaporation of ink from the ink supply will occur, eliminating the necessity for monitoring ink viscosity or adding solvents to the printing ink during printing. The printing machine further is economical in construction by eliminating the necessity for costly gravure printing cylinders and ink transfer pumps typical of the prior art gravure printing machines. The printing module 12 of the machine further is adapted for easy field modification, with the module 12 being readily positionable onto the drive shaft 30 of conventional printing machines in place of the gravure printing cylinder.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3835773 | Vasilantone | Sep 1974 | A |
| 5423252 | Yamamoto et al. | Jun 1995 | A |
| 5806419 | Adner et al. | Sep 1998 | A |
| 5954189 | Averill | Sep 1999 | A |
| 6035779 | Helms | Mar 2000 | A |
| 6129012 | Dietz et al. | Oct 2000 | A |
| 6276266 | Dietz et al. | Aug 2001 | B1 |
| Number | Date | Country | |
|---|---|---|---|
| 20050257701 A1 | Nov 2005 | US |
