Pad printing machine

At least one printing unit which can be moved into a print-image pickup position and into a print-image transfer position fitted with a first printing pad support involving a first pad support system or first pad seat for a first printing pad and a printing plate carrier to receive a printing plate, said printing unit also including a second pad support fitted with a second support system or second pad seat for a second printing pad, the two pad supports are such that the first support system of the first pad support and the second seat or second support system of the first pad support and the second pickup or second support system of the second pad support face each other at least when in the print-image transfer position.

RELATED APPLICATIONS

The present application is national phase of PCT/IB2009/053493 filed Aug. 7, 2009, and claims priority from, German Application Number 10 2008 046 487.2, filed Sep. 9, 2008.

The present printing machine relates to a pad printing machine.

The pad printing machines known from the above disclosures serve to print a particular zone of an object either in monochrome or multichrome manner, namely in a single step monochromely or in several steps multichromely. Moreover pad printing machines also are known that illustratively print for instance dishwasher panels or washing machine panels in several printing stages.

More specifically, however, as regards printing on several sides, the state of the art requires rotating the object for instance by 90 or 180° after the first side has been printed, to proceed to printing a second or further side. Regarding circular objects which can be printed using an appropriate pad across an approximately semicircular segment, the state of the art requires rotating the object by 180° after the first side was printed to allow printing the second side and in this manner being able to apply printing to the full circumference.

Accurate positioning of the object being printed in monochrome or multichrome manner requires a specially designed object support that must adapt to corresponding changes in position and therefore entails a complex structure as well as being time-consuming, due to object repositioning. Printing two sides moreover requires the time interval of two printing cycles.

Based on the above cited state of the art, the object of the present invention is to create a printing machine of much simplified design and able to print an object on two or more sides and also all around it in minimal time.

The present invention solves this problem by a pad printing machine.

Further features of the present invention are defined in the dependent claims.

FIG. 1is a partial view of a printing unit of a pad printing machine of the invention. A printing unit of the first embodiment mode comprises a first and a second pad support2and4respectively which are linked by bar-shaped or tubular connecting elements6,8to actuating levers10,12. More specifically, the connecting elements6,8are rigidly joined at one end6a,8ato the pad supports2,4and linked at their second end6b,8baccording to an appropriate design—namely hinge bolts14,16in the shown first embodiment mode—to the actuating levers10,12respectively articulating on them in a manner allowing rotation respectively pivoting about an axis of rotation respectively about a pivot axis running parallel to and concentric with the hinge bolts14,16.

The actuating levers10,12are pivoted by hinge bolts18,20about an axis perpendicular to its pertinent actuating lever, said axis in turn being parallel to and concentric with the hinge bolt18,20. As already mentioned above, the actuating levers10,12are linked to the connecting elements6,8at a particular first end10a,12a, namely the lower end and are linked by a particular second end10b,12b, namely the upper end, to first ends28a,30aof a toggle lever22, again by means of hinge bolts24,26. The toggle lever22is composed of two legs28,30which are linked by the hinge bolts32at their second ends28b,30bopposite the hinge bolts24,26, and is operationally engaged (by means of the hinge bolt32) with a bar-shaped drive element34vertically displaceable, as indicated by the double arrow36, within the pad printing machine. The drive element34in turn is powered in this particular embodiment mode by an electric motor and a pertinent mechanism transducing said motor's rotation into a vertical displacement of said drive element34. Alternatively, such a drive obviously also might be pneumatic or hydraulic. All joints/links allow rotation respectively pivoting about axes parallel to and concentric with the hinge bolts.

In addition to the above discussed components, the first embodiment mode of the pad printing machine of the present invention also includes an approximately planar printing plate carrier38also displaceable as indicated by the double arrow40also in vertical manner within the pad printing machine in particular relative to the pad supports2,4and the printing unit components connected to said supports. The printing plate carrier38is configured as a rest for a first printing plate42configured on the side of said carrier38facing the pad support2and to hold a second printing plate44resting on said printing plate carrier side facing the pad support4.

A print image is constituted by one or more recesses in each of the surfaces of the printing plate42,44that areaway from the printing plate carrier38. Ink cups46,48each fitted with a cup rim acting as a doctor scraper facing the printing plate are constituted on the print-image fitted surface of the particular printing plate42,44and may be produced by etching the said plates or by other techniques.

The ink cups46,48are held by magnets—which are configured internally in the present embodiment mode—on the printing plates42,44. For that purpose, the printing plate carrier38of the present embodiment mode is made of a ferromagnetic material. Alternatively the printing plate carrier38and the printing plates42,44may all be ferromagnetic. Again, the ink cups46,48may be kept mechanically, for instance by spring action, on the printing plates42,44, respectively being pressed against it. The ink cups46,48are rigidly joined to the pad printing machine, as a result of which the printing plate carrier38together with the printing plates42,44is displaceable relative to the ink cups46,48as indicated by the double arrow40. When the printing plate carrier38is moved vertically together with the printing plates42,44, the latter are displaced relative to said ink cups and may be moved from an “upper position” in which the print images are completely covered by the ink cups46,48to a “lower position” wherein they assume the position illustratively shown inFIG. 1.

Printing pads54,56are used to pick up ink (print-image pickup position) and are configured respectively affixed on the pad supports2,4—in this particular embodiment mode using a pad affixation system respectively pad seat58,60not elucidated any further using a quick connect element—over at least part of the printing plate42,44in particular synchronously respectively simultaneously to pick up ink from the print image. This procedure is indicated inFIG. 1by the arrows62,64. Such a procedure reliably transfers ink from the printing plates42,44to the particular printing pad54,56. The printing pads54,56are designed to assure ink transfer from the printing plate42,44to an object to be printed, (hereafter “object), when it is in its print-image pickup position underneath the printing pads54,56and underneath the printing plate carrier38respectively the printing plates42,44, said object50also being configured in vertically displaceable manner (double arrow52). The printing pad supports2,4as well as the printing pads54,56operationally engaging them are configured in a manner that they face each other. In other words, the particular pad support system respectively pad seat58,60is configured at its associated pad support2,4on that side at which the printing pad54,56shall be situated which in each case faces the other pad support system respectively pad seat60,58.

FIGS. 1 through 4show a printing cycle of the first embodiment mode of the pad printing machine of the present invention. As already discussed above, the printing plate carrier38ofFIG. 1, which carries on its sides an etched printing plate42,44, is situated in a lower position wherein, following the closure indicated by the arrows62,64of the “pad claws”, the printing pads54,56are able to pick up ink from their associated printing plates42,44. In the present embodiment mode, the printing plates42,44are magnetic and hence are reliably affixed to the printing plate carrier38. The pad claws being closed, the two pads54,56are able to pick up ink from the printing plates42,44by pressing, as already discussed above, bilaterally and preferably simultaneously against the printing plates42,44as indicated by the arrows62,64.

After the ink has been transferred from the printing plates42,44onto the printing pads54,56, the printing plate38carrier together with the printing plates42,44is moved out of the region of the pads54,56, as indicated inFIG. 2and by the arrow66. For that purpose the printing plate carrier38is moved upward and the etched structures in the printing plates42,44are replenished with ink from the ink cups46,48situated above said structures and also dwelling above the print image.

After, or, alternatively also simultaneously with, the upward displacement of the printing plate carrier38, the object50(FIG. 3) is moved upward between the two printing pads54,56as indicated by the arrow68. Obviously an alternative design also might be used, whereby the pads54,56together with the pad supports2,4and the remaining mechanism linked to same—namely the claws-shaped structure to which the pads54,56are affixed—are moved downward. Changing the position of the object50, in particular where such objects are substantially susceptible to sagging, also may be implemented in that, for the print-image pickup position ofFIG. 1, such sagging object50is suspended past the region between the printing pads54,56, therefore not between them. In order to subsequently position said object between said pads, the sagging object only need then be tautened. Sagging objects50for instance may be cables or ropes or objects with similar properties.

The position shown inFIGS. 3 and 4is intermediate in each case between the print-image pickup position and the print-image transfer position, the latter being the position wherein the object50is being printed, that is, where the printing pads54.56transfer ink to the object50. To implement such printing, the connecting elements6,8together with the printing pad carriers2,4and the printing pads54,56joined to the position changing levers10,12are moved toward the object50as indicated by arrows70,72. The “pad claws” close and in the process deliver ink to the object50guided between the pads54,56which in the closed position encompass and hold it. In the embodiment mode under discussion, ink transfer takes place simultaneously respectively synchronously to both sides of the said object. In other words, as regards the design of the said first embodiment mode, both actuating levers10,12together with the pads supports2,4and the printing pads54,56are simultaneously/synchronously set into motion and in that manner impact the object50. This feature facilitates holding/handling the object50because allowing eliminating complex object-supporting systems and handling devices, especially as regards sagging-susceptible objects and hence may be eliminated. In this embodiment mode, the object50is supported/handled essentially by the printing pads54,56simultaneously being applied to said object.

Alternatively, in another embodiment mode, the actuating levers10,12driven in a manner that they are set in motion at different time values while nevertheless the associated printing pads54,56simultaneously respectively synchronously impact the object50by employing different lever arm lengths in the actuating levers10,12, that is, different drive points.

In another alternative embodiment mode, the printing pads54,56may be configured in a manner that they be at different (time) phases, i.e. that they impact the object50at different time values. This feature illustratively may be applied to sagging objects50which may be tensioned by the printing pad that first impacts said object and then continues in its motion. In this embodiment variant the pad first impacting the object50also may be matched in its geometry to the said objector be fitted with a recess or the like.

Be it borne in mind that the displacement of the printing plate carrier38of the above discussed embodiment mode is vertical in order to flood the print image with ink in simple and reliable manner, such ink always being present in the particular lower half of the corresponding ink cup46,48. In an alternative, another embodiment might be used, whereby the printing plate carrier38is configured horizontally and also does move horizontally. Such an embodiment mode is elucidated below in relation toFIGS. 8 through 10.

The displacement of the pad claws of the first above described embodiment mode may also be implemented using the centrally actuated toggle lever22as shown above, however it may furthermore be implemented using an arbitrarily different kind of drive such as one or more of a direct electric, pneumatic of hydraulic drive, a drive based on an adjusting or spindle motor, or other drives. On account of the ability of the printing pads54,56to move simultaneously toward the object50, respectively that these pads simultaneously make contact with said object, the latter is both maintained in place, that is its if fixed in its position and also is supported, a good support being attained thereby for sagging objects50, together with good assurance of precluding positional shifting.

The equipment of the above described first embodiment mode is shown again inFIGS. 5 and 6in a different view also showing the object50and a dispenser roll74and a windup roll76used for the object50.FIG. 5shows the structure in the print-image transfer position (the “claws” closed around the object50) andFIG. 6shows said structure in the print-image pickup position wherein—for the shown alternative of the first embodiment mode—the dispenser roll74and the windup roll76are lowered. An alternative representation might be of the print claws being moved upward and/or the object50being tensioned between support respective rest elements78,80in the print transfer position ofFIG. 5, whereas the object in the print-image pickup position ofFIG. 6is “sagging” between the support sites70and80, i.e. it bulges in the downward direction. The vertical displaceability of the dispenser roll74and the windup roll76as well as of the object50again is indicated by double arrows52.

FIG. 7shows a second embodiment mode of a pad printing machine of the present invention. Its design is substantially the same as that of the first embodiment mode. In the second embodiment mode, however, the object50is rigid rather than susceptible to sagging—for instance it may be cylindrical like a cup, a pipe segment or the like—and shall be printed on two sides. For that purpose, and contrary to the case of the first embodiment mode comprising the dispenser roll74and the windup roll76, an object support82is used to keep the object50in the desired position. This object support82consists of clamping jaws84and clamping jaw excursion elements86made of a soft material, preferably rubber, to move said clamping jaws toward and away from said object. In an alternative, arbitrarily different object supports may be used, illustrative picking up objects yet to be printed and situated for instance in a recess or picking them up using dowels or cylindrical pins or other such elements and holding said objects.

FIGS. 8 and 9show a third embodiment mode of the pad printing machine of the present invention in a partial side view and in the print-image transfer position. The pad printing machine of the third embodiment mode like the previous described embodiment modes comprises two printing pads54,56which again are configured respectively kept in place in pad supports2,4. The pad supports2,4are configured respectively affixed on pad support carriers92,94. These pad support carriers92,94again are operationally connected in compressively locked manner to the connecting elements6,8that, on their side away from the pad support carriers92,94, are linked to a support system96. In the embodiment being discussed, the linkage is implemented by omitted hinge bolts. Obviously any other linkage may also be used.

The support system96of the embodiment mode under discussion is vertically displaceable in the pad printing machine as indicated by the arrow98. As a result (FIG. 8) the printing pads54,56can be moved toward and away from the horizontally configured printing plate42which is mounted, again as in the previously described embodiment modes, on the printing plate carrier38. The printing plate carrier38together with the printing plate42is horizontally displaceable as indicated by the double arrow100, as a result of which, following ink transfer to the pads54,56, the printing plate42together with the printing plate carrier38can be moved horizontally, and the way is clear for the printing pads54,56to the object50.

To pick up ink, the tips, i.e. the “active” sides used for printing of the pads54,56point in the direction of the horizontal printing plate42. This also means that the pickup surfaces58,60of the pad supports2,4are configured horizontally. The print-image transfer position is shown inFIG. 9, and, to transfer the print image, the printing pads54,56are pivoted by 90° about pivots102,104running perpendicularly to the plane of the drawing, as a result of which the “active” sides of the pads54,56respectively the pad support systems respectively seats58,60are configured vertically. Following print-image transfer, the pads54,56are pivoted back by 90° and the printing plate42is moved underneath the printing pads54,56in order to again assume their print-image pickup position. While the printing plate42is displaced horizontally, it will be flooded with ink from the ink cup omitted from this drawing. Alternatively to the vertically displaceability of the support system96and the horizontal displaceability of the printing plate carrier38together with the printing plate42, illustratively the support system96might be displaceable both vertically and horizontally or the printing plate42together with the printing plate carrier38shall be displaceable both horizontally and vertically, or the object50shall be displaceable both horizontally and vertically.

FIG. 10shows a fourth embodiment mode of a pad printing machine of the present invention differing from the above first and second embodiment modes in that the printing pads54,56and also the pad supports2,4as well as the connecting elements6,8are configured to be vertically displaceable as indicated by the double arrows88,90. In other words, objects50are printed simultaneously from above and below while being held in place by a corresponding supporting respectively tensioning system as described above for instance in relation toFIG. 7. In a variant of the above discussed embodiments, however, the printing plate carrier38is not configured vertically, but horizontally, as a result of which one of the omitted ink cups46,48omitted fromFIG. 8rests on the head. The desired feed of ink may be assured for instance by applying a slight excess pressure in the pertinent ink cup46,48or by similar appropriate measures (permanently keeping them filled).

Lastly, be it borne in mind in some instances, namely in the first, second and fourth embodiment modes, that a printing plate carrier38fitted with bilateral seats for the printing plates42,44, also several printing plate carriers may be used that are designed each to provide one seat to receive the printing plate. The printing pads used for the above discussed embodiment modes preferably shall be soft to very soft.

Even though the present invention was discussed above in relation to several embodiment modes exhibiting well defined feature combinations, said invention also covers further conceivable advantageous combinations such as those defined in non-restrictive manner in the dependent claims. All features disclosed in the application documents are claimed being inventive to the extent they are new over the state of the art, whether per se or in arbitrary combinations.