BRIEF DESCRIPTION OF THE DRAWINGS
Further features and benefits of the invention will be evident from the claims and the following description of preferred embodiments of the invention, together with the figures, which depict:
FIG. 1 is a frontal view of a squeegee according to a preferred embodiment of the invention;
FIG. 2 is a view of the squeegee shown in FIG. 1, shown here installed on a section of a device for screen-process printing;
FIG. 3 is a device for screen-process printing according to the invention; and
FIG. 4 is another embodiment of a device for screen-process printing according to the invention.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts a squeegee 10 according to the invention that has several grip segments 12, 14, 16. The squeegee 10 is attached to a squeegee holder (not shown) of a device for screen-process printing (also not shown) by way of the grip segments 12, 14, 16. The squeegee 10 also has an elastic applicator 18 consisting of, for example, an elastic rubber plate. The elastic applicator 18 is configured in the form of a monolithic unit over the full width of the squeegee 10 and is held in place at the location of every grip segment 12, 14, 16. The grip segments 12, 14, 16 are spaced at intervals and interconnected by the elastic applicator 18 only. The grip segments 12, 14, 16 are therefore free to move relative to one another.
A printing edge 20 of the squeegee 10 opposite the grip segments 12, 14, 16 is curved, where the curvature of the printing edge 20 is adapted to suit the surface curvature of an item to be imprinted.
A guide plate 22, 24, 26 extending downward from each grip segment 12, 14, 16, i.e., toward the printing edge 20, is attached to each grip segment 12, 14, 16. The guide plates 22, 24, 26 abut against the elastic applicator 18 in order to provide a uniform pressure distribution over the elastic applicator 18, and thus a uniform distribution of the pressure exerted by the printing edge 20 during a printing procedure. A lower edge of the guide plates 22, 24, 26 that faces away from the grip segments 12, 14, 16 is formed parallel to the printing edge 20 of the elastic applicator 18, which will provide for a uniform elastic behavior of the printing edge 20 over the full width of the squeegee 10.
That edge of the left guide plate 22, i.e., that on the left-hand grip segment 12 shown in FIG. 1, that faces the central guide plate 24 on the central grip segment 14 extends downward from the left-hand grip segment 12, toward a center of the printing edge 20, and toward the latter, rather than constituting an extension of the associated, left-hand, grip segment 12. That right-hand lateral edge of the left-hand guide plate 22 extends toward the center of the printing edge 20 to the extent that a projection, vertically upward in FIG. 1, of a corner of the left-hand guide plate 22 neighboring on the printing edge 20 will cover a left-hand border of the central grip segment 14, and thus also partially cover a left-hand border of the central guide plate 24. A left-hand, lateral, edge of the central guide plate 24 extending from the left-hand border of the central grip segment 14 also extends toward the center of the printing edge 20 and is approximately parallel to the right-hand lateral edge of the left-hand guide plate 22. The right-hand lateral edge of the central guide plate 24 is configured symmetrically thereto. The left-hand lateral edge of the right-hand guide plate 26 parallel to it is configured symmetrically to the right-hand lateral edge of the left-hand guide plate 22. That configuration of the guide plates 22, 24, 26 provides for an approximately uniform force distribution over the elastic applicator 18, and, in particular, over its printing edge 20.
FIG. 2 depicts the squeegee 10 shown in FIG. 1 assembled on a squeegee holder 28. It may be seen that every grip segment 12, 14, 16 is attached to the squeegee holder 28 by way of a pair of adjustment cylinders 30. Each adjustment cylinder 30 may be individually controlled by a controller 32 in order to set a location of the grip segments 12, 14, 16 relative to one another and a pressure exerted by the printing edge 20 of the squeegee 10 that varies over its width. Furthermore, the adjustment cylinders 30 may also be utilized for setting the pressure exerted by, and the location of, the printing edge 20 of the squeegee 10 during a printing procedure differently than for, for example, a return motion of the squeegee.
As may be seen in FIG. 2, the curved printing edge 20 of the squeegee 10 allows a uniform adaptation to suit the curved surface of an item 34 to be imprinted, for example, a final-shaped glass pane for an automobile. In the interest of simplicity, a printing screen that must, necessarily, be arranged between the squeegee 10 and the item 34 to be imprinted is not shown in FIG. 2. Due to the grip segments 12, 14, 16 that are free to move relative to one another and the facilities for individually adjusting the grip segments 12, 14, 16 using the adjustment cylinders 30, the squeegee 10 may also be adapted to suit curvatures of the item 34 to be imprinted that vary over its surface. In the event that the curvature of the item 34 to be imprinted varies along the longitudinal axis, that is, along the direction of motion of the squeegee 10, the curvature of its printing edge 20 will be matched to an average curvature of the item 34 to be imprinted.
The squeegee 10 according to the invention may thus be utilized for imprinting items, like the item 34 to be imprinted shown, that are curved transversely to the imprinting axis using a conventional device for screen-process printing.
If spherically curved items, for example, final-shaped glass panes for automobiles, are also to be imprinted, a device 40 for screen-process printing similar to that shown in FIG. 3, together with the squeegee 10 according to the invention, may be utilized for that purpose. In the case of the device 40 for screen-process printing, a printing frame 42 may undergo a tilting motion during a printing motion of the squeegee holder 44, together with a squeegee clamped therein, while the squeegee holder 44 is guided such that it remains approximately parallel to a longitudinally curved surface of an item 34 to be imprinted. To that end, the squeegee holder 44 is guided by slotted guides 46 that have been adapted to suit the longitudinal curvature, that is, the curvature along the squeegee's direction of motion, of an item to be imprinted. During the tilting motion of the printing frame 42, which is caused by the motion of the squeegee holder 44 that is guided on the printing frame 42, an underside of the printing frame 42 rocks on a surface parallel to the slotted guides 46, where the surfaces involved in that rocking motion are toothed in order that the printing frame 42 will be constrained from shifting its location longitudinally during a printing motion. Together with the squeegee 10 according to the invention, the device 40 for screen-process printing will thus allow imprinting spherically curved items, that is, items that are curved along both the longitudinal and lateral axes.
FIG. 4 depicts another embodiment of a device 50 for screen-process printing according to the invention. A spherically curved item 52 is to be imprinted using the device 50 for screen-process printing, where a curvature of the surface of the item 52 transverse to the longitudinal axis will be taken into account by the squeegee 10 according to the invention, which is merely schematically depicted in FIG. 4. The longitudinal curvature of the item 52 to be imprinted is taken into account by a tilting motion of a printing frame 54 that, in the case of this particular device 50 for screen-process printing, is generated using four column hoists 56 that are controllable by a controller (not shown). Suitably controlling the operations of the column hoists 56 will adjust the orientation of the printing frame 54 such that the printing frame 54, and thus a printing screen, which is not shown in FIG. 4, will be adjusted such that they remain tangential to an imaginary line of contact between the printing edge of the squeegee 10 and the surface of the item 52 to be imprinted at all times. In contrast to the device 40 for screen-process printing shown in FIG. 3, this device 50 for screen-process printing has column hoists 56 that may be freely programmed in order that reprogramming them will be all that is necessary in order to take into account differing curvatures of the items to be imprinted.
Patent Application
20080034989
