Description Title of Invention: PAD PRINTING MACHINE

[I] The present invention relates to a pad printing machine defined in the preamble of claim 1.

[2] Pad printing machines of this kind are known for instance from following documents:

[3] WO 2004/113075 Al, DE 10 2005 048 467 Al, DE 10 2005 060 550 Al and DE 10

2006 005 073 Al.

[4] Frequently and foremost as regards automation, pad printing machines can only be used when including an automated pad cleaning implement.

[5] As regards monochrome pad printing machines, the pad ordinarily is cleaned before or following a printing procedure.

[6] As regards polychrome printing, there are two conventional methods. In one of these, the pad is cleaned as for monochrome printing machines before or after a printing procedure. In the other method, the pad is cleaned while other pads are in use. This second method, which is known as regards polychrome printing machines, offers the advantage that the time required for pad cleaning does not affect the complete printing cycle.

[7] When cleaning before or after a printing procedure, such cleaning per se lengthens the total cycle. This total cycle is an important factor. Illustratively this is demonstrated by the phenomenon of the increasing use of polychrome printing machines even for monochrome printing to allow carrying out the integral cleaning cycle within the printing cycle.

[8] Conventionally two drives are needed, namely one drive to move the printing plate and another to move the pad. Such linear displacements usually are carried out pneumatically or by motors.

[9] The objective of the present invention is to solve the problem to integrate pad cleaning into the conventional printing procedure of a printing unit in a manner allowing pad cleaning within the conventional printing cycle.

[10] This problem is solved by the features of the claim 1 of the present invention.

[I I] Accordingly the present invention relates to a pad printing machine containing at least one monochrome printing unit designed for automated printing procedures and fitted for that purpose with a first pad support holding a pad and a printing plate support to hold a printing plate, said printing unit moreover being designed for automated cleaning operations and comprising for such a purpose a cleaning implement cleaning the first pad, characterized in that the same printing unit moreover comprises a second pad support to hold a second pad and is designed to exchange/

switch the positions of the two pad holders in a manner that in a first switch position the first of the pad supports together with its first pad is in an appropriate position to perform at least one printing procedure while the second pad support together with its second pad is in an appropriate position to carry out at least one cleaning operation, whereas, when in a second switch position, the first pad support together with its other pad is in an appropriate position to carry out at least one cleaning procedure, such cleaning taking place during one printing procedure.

[12] The present invention offers the advantage that as regards monochrome pad printing machines, the cleaning cycle falls within the printing cycle so that the time of a cleaning and printing cycle will be only the time of the printing cycle even when an additional cleaning cycle is carried out.

[13] Because the invention resorts to a second pad and an exchange/switch system, pad cleaning can be integrated into the conventional printing procedure without losing time.

[14] However the present invention is also applicable to polychrome printing units because they can be individually cleaned depending on the particular pad's soiling and/ or in relation to the ink used until cleaning becomes necessary. Each of the two printing unit pads may be used for printing until individually requiring cleaning. At that time the two pads are switched/interchanged with one another. This operation illustratively may be by carried out by rotating the pad support while the printing plate is advanced. Since this procedures is carried out simultaneously, no time loss is incurred.

[15] The various displacements of the printing unit components can be implemented by pneumatic, electric, hydraulic or mechanical drives.

[16] Further features of the invention are defined in the dependent claims.

[17] The present invention is discussed below in relation to the appended drawings and by means of several illustrative embodiment modes.

[18] Figs. 1-11 show various operational conditions during a printing cycle and a cleaning cycle of a monochrome pad printing machine schematically shown in side view,

[19] Figs. 12 - 18 show various operational conditions in the course of a printing cycle of a printing unit of a pad printing machine of the invention, while a simultaneous cleaning cycles evolves, the printing unit being shown in side view and being part of a monochrome pad printing machine, or being a printing unit of a polychrome pad printing machine,

[20] Figs. 19 - 25 show the same printing unit of the invention in different operational conditions as in Figs. 12 - 18, however the pads being interchanged/switched,

[21] Fig. 26 schematically shows a top view of a further embodiment mode of a printing unit of a pad printing machine of the invention,

[22] Fig. 27 is a side view of the pad printing machine of Fig. 26 as seen in the direction

of an arrow A of Fig. 26,

[23] Fig. 28 is a partial sectional view along the plane B-B of Fig. 26, and

[24] Fig. 29 is a front view of the pad printing machine seen in the direction of an arrow

C of Fig. 27.

[25] Figs. 1 through 11 show a known printing unit of a known monochrome pad printing machine of the present invention. It contains a first pad support 4 holding a first pad 6 and a printing plate support 8 holding a printing plate 10 and a cleaning implement 12. Preferably the cleaning implement 12 contains a cleaning band 14 to clean the printing side 6-1 of the pad 6. An object carrier 16 may be provided to carry an object 18 to be printed by the pad 6.

[26] A pad drive 20 serves to move up and down the pad support 4 together with the pad

6. A printing plate drive 22 advances and retracts the printing plate 10 respectively into and from displacement zone of the pad 6. The drives 20 and 22 may be pneumatic, hydraulic, electric, electromagnetic or other.

[27] The printing plate 10 is displaceable relative to an ink cup 24 which is held in a predetermined position by an ink cup support 26. When in said predetermined position, the ink cup 24 is situated above a printing recess which, depending on the print to be applied, for instance a text or a graphic, is constituted in the upper surface of the printing plate 10 and in this manner may receive ink from the open, lower end of the ink cup 24. When the printing plate 10 is horizontally displaced from the retracted position shown in Fig. 1 into the advanced position shown in Fig. 2, the print image recess 28 is moved out of the zone of the ink cup 24 and underneath the pad 6. The downward-pointing rim of the downwardly open ink cup 24 is designed as a doctor blade sliding along the upper surface of the printing plate.

[28] The operational steps automatically implementing the printing procedures during a printing cycle and automated cleaning cycles during a cleaning cycle are discussed below in relation to Figs. 1 through 11.

[29] Fig. 1 shows the basic position of the printing unit wherein the pad 6 (printing stamp) is at the top and the printing plate 16 is retracted.

[30] Fig. 2 illustrates a first procedural step wherein the printing plate 10 is advanced from its retracted basic position along an arrow 30 into a printing position and as a result the print image recess 28 is positioned underneath the pad 6. The pad 6 may already begin descending during this forward motion of the printing plate 10. In another (omitted) embodiment mode, the pad might be displaced sideways, transversely to the printing plate 10 in order to position it above the print image recess 28 of the printing plate 10.

[31] In the second procedural step shown in Fig. 3, the pad 6 descends in the direction of the arrow 32 onto the printing plate 10 to pick up ink from said plate's print image

recess 28.

[32] In the third procedural step shown in Fig. 4, the pad 6 is moved upwards as indicated by an arrow 34 back into its initial position.

[33] As regards the fourth procedural step shown in Fig. 5, the printing plate 10 is returned as indicated b an arrow 36 horizontally into its initial position of Fig. 1. In another embodiment mode the pad 6 already above the object 18 can be displaced over it.

[34] In the fifth procedural step shown in Fig. 6, the pad 6 can descend as indicated by an arrow 32 down again until it transfers the ink onto the object 18.

[35] In the sixth procedural step shown in Fig. 7, the pad 6 is moved back from the object

18 in an upward excursion indicated by an arrow 34.

[36] In the seventh procedural step shown in Fig. 8, the cleaning implement 12 is moved as indicated by an arrow 38 underneath the pad 6 which already during said motion can start its descent. In another embodiment mode the pad 6 may be displaced laterally above the cleaning implement 12 instead of said implement being moved underneath said pad.

[37] In the eight procedural step shown in Fig. 9, the pad 6 by its printing side 6-1 makes contact with the cleaning belt 14 of the cleaning implement 12, as a result of which the residual ink adhering to said pad's printing side remains adhering to the cleaning band 14.

[38] In the ninth procedural step shown in Fig. 10, the pad rises again.

[39] In the tenth procedural step shown in Fig. 11, the cleaning implement 12 moves as indicated by the arrow 40 back into its initial position. Thereby the total cycle of this known printing unit of Figs. 1 through 11, which consists of the printing cycle and the ensuing cleaning cycle, is terminated. However a cleaning cycle also may be applied only after several printing cycles.

[40] The present invention is described below in relation to a preferred embodiment mode of a pad printing machine of the present invention. The same components discussed below as were already discussed above shall be denoted also by the same reference numerals.

[41] Fig. 12 shows the pad printing machine of the present invention in a first basic position. Said machine comprises a first pad support 4 holding a first pad 6, further the printing plate support 8 together with the printing plate 10 and the cleaning implement 12 which illustratively is again fitted with a pad cleaning band 14. The cleaning pad illustratively may be a stick-on cleaning tape. An element other than a band or tape also might be used.

[42] The same printing unit as just above contains a second pad support 44 holding a second pad 46 fitted with a printing side 46-1. The shown printing unit also is fitted

with an switching element 50 (Fig. 13) to alternatingly switch the positions of the two pad supports 4 and 44, said element being designed in a manner that after occupying a first switch position, the first pad support 4 together with its pad 6 shall be configured for at least one printing operation whereas the second pad support 44 together with its second pad 46 shall be configured for at least one cleaning operation, and in that for a second switch position, the second pad holder 44 together with its second pad 46 shall be configured to carry out at least one printing operation while the related first pad support 4 together with its first pad 6 shall be configured to carry out at least one cleaning operation. Depending on the printing unit design, each printing operation may be followed by one cleaning operation or one cleaning operation may be carried out after a given number of printing operations. Applying a cleaning operation may be made dependent on the degree of soiling incurred by the particular pad.

[43] The embodiment mode of the present invention shown in Figs. 12 through 25 includes a horizontal pad axis of rotation 52 about which both the pad support 4 and the pad support 44 are configured rotatably.

[44] As shown by the pad printing machine of Figs. 12 through 25, the pad axis of rotation 52 is horizontal and the pad supports 4 and 44 are designed and configured in a manner that the printing side 6-1 and 46-1 of the two pads 6 and 46 respectively point in a direction 6-2 and 46-2 which is orthogonal to the pad's axis of rotation 52.

[45] Preferably a carrier 54 is used, which constitutes one of the two pad supports 4 and

44 or to which both are affixed so that they only may rotate jointly about the axis of rotation 52. The rotation of the carrier 54 jointly with the two pad supports 4 and 44 about the axis of rotation 52 of the switching element 50 preferably is implemented by a third drive 56. This third drive 56 may be electrical, pneumatic, hydraulic, electromagnetic or of another kind, illustratively being an electric motor.

[46] Again a drive 20 may used to raise and lower the pad axis of rotation 52 jointly with the two pad supports 4 and 44 and their pads 6 and 46 respectively and the third drive 56, said drive 20 being connected with a shaft constituting the pad axis of rotation or another element to raise/lower them. The two pad supports 4 and 44 together with their pads are moved up and down simultaneously.

[47] The following description relates to the procedural steps of Figs. 12 through 25 implementing one or more cleaning operations within one printing cycle, one cleaning operation being implementable simultaneously in time with/within one printing cycle. In every embodiment mode, one cleaning operation may be performed during each printing cycle or only following a given number of printing cycles, though always simultaneously with/within one printing cycle.

[48] Illustratively the cleaning element of the cleaning implement may be a cleaning band, for instance a stick-on band fitted with a pad-contacting surface. The cleaning band 14

may run around two rolls or wind its way from one roll 12-1 onto a second roll 12-2.

[49] Fig. 12 shows the printing unit of the present invention being in a first basic position.

In this instance the pads 6 and 46 are situated up and the printing plate 10 is in its retracted initial position, the first pad 6 pointing upward though its printing side 6- 1 is vertically spaced from the cleaning element 14 of the cleaning implement 12, whereas the printing side 46- 1 of the second pad 46 points in the opposite direction, namely down.

[50] In the first procedural step shown in Fig. 13, the printing plate 10 is moved from its initial position as indicated by an arrow 30 horizontally into an ink transfer position, as a result of which a print image recess 28 shall be positioned underneath a pad. The pad support 54 together with the first pad 6 is rotated downward as indicated by an arrow 58.

[51] The two pad supports 4 and 44 are configured radially to the axis of rotation 52 preferably being mutually offset by 180°, as a result of which their printing sides 6-1 and 46- 1 are configured on one diametrical line of the pad's axis of rotation 52 while pointing in mutually opposite directions 6-2 respectively 46-2.

[52] Besides a design comprising two pad supports 4, 44, designs comprising more than two, for instance four or six pad supports are conceivable which may be distributed in particular in regular manner (that is four pad supports equidistant from one another by 90° at the carrier 54 or six pad supports being equidistant by 60° between adjacent supports at the carrier 54).

[53] The cleaning implement 12 is situated by its cleaning element 14, for instance a horizontal cleaning band or a stick-on tape, vertically above the pad axis of rotation 52 and the two pads 6 and 46.

[54] As regards the second procedural step illustrated in Fig. 14, the first pad 6, which was rotated downward and displaced down as indicated by an arrow 32, makes contact with the printing plate 10 in its advanced position at said plates print image recess 28. In this manner the printing side 6- 1 of the first pad 6 absorbs ink from said print image recess.

[55] In the third procedural step shown in Fig. 15, the first pad 6 together with the second pad 46 and jointly with the pad shaft 53 defining the axis of rotation 52 are moved back upward as indicated by an arrow 34.

[56] In the fourth procedural step shown in Fig. 16, the printing plate 10 is returned into its initial position as indicated by an arrow 36. In the time interval during which the printing plate is moved back, the two vertically positioned pads 6 and 46 are displaced from the second basic position shown in Fig. 15 into the cleaning position shown in Fig. 16 wherein the second pad 46 makes contact by its printing side 46-1 with the cleaning element such as a cleaning band 14 of the cleaning implement 12 and is

cleaned thereby. An arrow 34-1 indicates the upward displacement of the second pad 46 — which also displaces the first pad 6 upward — from the second basic position of Fig. 15 into the cleaning position of Fig. 16.

[57] In the fifth procedural step shown in Fig. 17, the first pad 6 is moved down onto an object 18 as indicated by an arrow 32 in order to transfer the ink in the form of a desired print image onto the object 18. The print image may be a graphic and/or a script. The two pads 6 and 46 being linked to each other, they are always displaced simultaneously up and down. Being configured opposite to each other, however, only the down-pointing pad, in Fig. 17 the pad 6, does touch the object 18.

[58] In the sixth procedural step shown in Fig. 18, the first pad 6 is moved as indicated by an arrow 34 from the object 18 upward into the second basic position. In said second basic position the second pad 46 is vertically apart from the cleaning element 14 of the cleaning implement 12. In the Figs. 12 and 18 all components are in the first (Fig. 12) or the second (Fig. 18) basic positions. A printing cycle has been completed in this manner, during which a cleaning cycle also was carried out.

[59] Henceforth a new printing cycle may begin, wherein the second pad 46 is used for printing, and the first pad 6 is cleaned during this new printing cycle, as a result of which the cleaning and printing cycles are not sequential but simultaneously with each other.

[60] Fig. 19 shows the second basic position wherein the second pad 46 points up but its printing side 46-1 is vertically apart from the cleaning element 14 of the cleaning implement 12 and where the first pad 6 points down in the opposite direction by its printing side 6-1.

[61] Fig. 20 shows the first procedural step wherein the printing plate 10 is moved as indicated by an arrow 30 from the second basic position horizontally forward into an ink transfer position while simultaneously the second pad 46 as indicated by an arrow 58 is rotated downward about the horizontal axis of rotation 52.

[62] In the second procedural step shown in Fig. 21, the two pads 6 and 44, the latter pointing down, are displaced as indicated by an arrow 32 into an ink transfer position where the second pad 46 picks up ink from the printing plate 10.

[63] In the third procedural step shown in Fig. 22, the second pad 46 and hence with it the first pad 6 also, moves again, as indicated by an arrow 34, upward into the first basic position.

[64] In the fourth procedural step shown in Fig. 23, the printing plate 10 moves as indicated by the arrow 36 from the ink transfer position back into the basic position. During this time interval the first pad 6 is moved farther upward as indicated by an arrow 34- 1 from the first basic position until it makes contact with the cleaning element 14 of the cleaning implement 12 where it is then cleaned.

[65] In the fifth procedural step shown in Fig. 24 the second pad 46 is moved downward as indicated by an arrow 32 onto the object, the second pad 46 transferring the ink onto the object 18.

[66] In the sixth procedural step shown in Fig. 25, the second pad 46 and together with it also the first pad 6 is moved as indicated by an arrow 34 upward into the first basic position. This step then terminates the total cycle encompassing both the printing cycle and a cleaning cycle bounded within the said printing cycle. While one pad is in the printing cycle, the other pad is in its cleaning cycle, and vice- versa. The basic position of Fig. 25 attained at the end of the total cycle corresponds to the first basic position of Fig. 12.

[67] Using a single, illustratively regulated or controlled drive 20, such a design makes it possible that individually adjustable ways relating to the object 18 and the cleaning band 14 be implemented. Also the drive may be made comparatively compact because a force shall be needed only for one procedure (either printing or cleaning).

[68] The further embodiment mode of a pad printing machine's printing unit shown in

Figs. 26 through 29 may be used in single or plural manner in a polychrome or preferably a monochrome pad printing machine.

[69] The printing unit is shown in top view in Fig. 26; in side view in Fig. 27 corresponding to an arrow A of Fig. 26; and in front view in Fig. 29 corresponding to an arrow C of Fig. 27. Fig. 28 is a sectional view in the plane B-B of Fig. 26.

[70] The embodiment mode of the present invention shown in Figs. 26 through 29 differs essentially from the first above-described embodiment mode of the invention by including a changeover device, i.e. a switching element 150 fitted with a vertical axis of rotation 152 illustratively subtended by a vertical shaft 153 that is both rotatable and vertically reciprocable for instance by means of a drive 120 which may be pneumatic, electrical, hydraulic, electromagnetic or other.

[71] The first pad support 4 together with the first pad 6 and the second pad support 44 together with the second pad 46 are configured on diametrically opposite sides of the vertical axis of rotation 152 each parallel to said axis in a way that the printing side 6-1 of the first pad 6 and the printing side 46-1 of the second pad 46 run both parallel to the axis of rotation 132 while pointing down. The two pad supports 4 and 44 are irrota- tionally connected by a carrier 154 to the vertical shaft 153, as a result of which they rotate jointly with the vertical shaft 153 and jointly move up and down.

[72] A printing plate support 8 bears a printing plate 10 and can be driven by a drive 20 in a straight advance or retraction as indicated by the arrows 30 and 36 between the shown basic position and an omitted ink transfer position whereas the ink cup 24 is stationary. In its ink transfer position, the printing plate 10 is situated underneath one of the two pads 6 or 46, in the case illustrated by Fig. 26, it is associated with the first

pad 6. By rotating the vertical shaft 153 about the vertical axis of rotation 152 by 180°, the positions of the pad supports 4 and 44 together with their pods 6 and 46 are mutually interchanged. A cleaning element 14, illustratively again a cleaning band, preferably a stick-on tape, of a cleaning implement 112 is displaceable using a further drive 113 is — as indicated by arrows 130, 136 — linearly and parallel to the direction of displacement 30 respectively 36 of the printing plate support 8, and the cleaning element 14 of the cleaning implement 112 is alternatively displaceable forward between the basic position shown in Fig. 26 wherein it is not underneath one of the pads 6 or 46, and a cleaning position underneath the particular pad requiring cleaning, which illustratively in Fig. 26 is the pad 46.

[73] When both the printing plate support 8 and the cleaning element 14 are in their retracted basic positions as shown in Fig. 26, they shall be outside the displacement path of the pads 6 and 46 and their pad supports 4 and 44.

[74] When only the printing plate 10 together with the printing plate support 8 are moved from the shown basic position into the omitted ink transfer position, the printing plate print image recess 28 moves underneath the pad, as regards the operational condition shown in Fig. 26 under the first pad 6 of the first pad support 4. When next the vertical shaft 153 is lowered together with the two pad supports 4 and 44, the particular pad 6 is able to contact the printing plate 10 and absorb ink from it. In Fig. 26, it is the first pad 6 which can pick up the ink.

[75] In a subsequent procedural step the shaft 153 together with the two pads 6 and 46 are raised again into a basic position and the printing plate 10 together with the printing support 8 is returned from the ink transfer position into the retracted basic position.

[76] In the following procedural step the shaft 153 together with the two pads can be lowered again, as a result of which the printing side having picked up the ink — for instance the printing side 6-1 of the first pad 6 of Fig. 26 — can make contact with an object 18 on an object carrier 16 and transfer the ink and hence the print image onto the object 18.

[77] After one or more of such printing procedures the cleaning element 14 can be displaced individually or preferably jointly with the printing plate support 8 from the basic position forward and underneath the pad, namely the second pad 46 in Fig. 26, which unlike the first pad 6 is not in the printing position. The pad not in the printing position, in Fig. 26 the second pad 46, during said descent is able to make contact with the cleaning element 14 and can be cleaned in the process. Simultaneously one of the pads, in Fig. 26 the first pad 6, can pick up ink from the printing plate 10.

[78] Thereupon the first pad 6 can print another object 18.

[79] Thereupon the pad carrier 154 may be rotated by 180° about the vertical axis of rotation 152 whereby the first pad support 4 together with the first pad 6 exchanges

places with the second pad support 44 and latter's pad 46.

[80] After this switch or exchange, the second pad 46 can pick up ink from the printing plate 10 and transfer it onto an object 18 and the first pad 6 can be cleaned by the cleaning element 14.

[81] The printing plate support 8 and the cleaning implement 112 may be mounted on separate carriers or on a common carrier 116. This carrier may be separate from the object carrier 116 or both may be joined to each other or may be one integral component.

[82] In all embodiment modes the principle of the present invention calls for fitting one printing unit with two pads which can be moved into a given position in alternating manner to print and to clean, the cleaning procedure being feasible within one printing procedure and requiring no additional time to that of the printing procedure per se. It must be borne in mind regarding all embodiment modes of the present invention that the above described relative displacements of the various components may take place not only as illustrated above, but that merely one component be moved relative to the other regardless of which one of the two is being moved and which one is at rest. Illustratively, the raising and lowering of the pad may be replaced by raising and lowering the object carrier 16 together with the object 18 where ink must be transferred from the particular pad 6 or 46 onto the object 18. Again the horizontal axis of rotation 52 of the first-cited embodiment mode of the present invention and the vertical axis of rotation 152 of the second embodiment mode of the present invention may be configured in horizontally displaceable manner, for instance to move the particular pad selected for printing above the printing plate, and/or to displace the particular pad selected for printing at different positions of the object 18 or toward different objects. Also embodiments are feasible wherein the printing plate support 8 cannot be shifted or rotated while the ink cup 24 is stationary, but the reverse, configuring the printing plate support 8 in stationary manner while the position of the ink cup 24 is variable.

[83] Identical components in all drawings are denoted by the same reference numerals and many of such components are described only once. Components shown in Figs. 26 through 29 while operationally the same but incongruent technically are identified by reference numerals raised by 100 relative to the other Figures.