EP2776248A2

EP2776248A2 - Screen printing doctor blade and device for screen printing

Info

Publication number: EP2776248A2
Application number: EP12783973.6A
Authority: EP
Inventors: Harry Götz
Original assignee: Thieme GmbH and Co KG
Current assignee: Thieme GmbH and Co KG
Priority date: 2011-11-07
Filing date: 2012-11-05
Publication date: 2014-09-17
Anticipated expiration: 2032-11-05
Also published as: PL2776248T3; WO2013068317A3; HUE031384T2; EP2776248B1; DE202011107661U1; WO2013068317A2; US20130139710A1; US8985015B2

Abstract

The invention relates to a screen printing doctor blade and to a device for screen printing. The invention relates to a screen printing doctor blade having an elastic application element and a maintaining device for the application element, said maintaining device being divided into several maintaining sections which can be moved in relation to each other when seen over the width of the application element, a leaf spring element which interconnects the maintaining sections which can be moved in relation to each other, is provided.

Description

description

Screening squeegee and device for screen printing

The invention relates to a screen printing squeegee with an elastic applicator element and a holding device for the applicator element, wherein the holding device is divided over the width of the applicator element into a plurality of mutually movable holding sections. The invention also relates to a device for screen printing with a screen printing squeegee according to the invention.

International Publication WO 2005/035250 A1 discloses a screen-printing squeegee with an elastic applicator element in the form of a plate-shaped squeegee rubber. The plate-shaped squeegee rubber is provided with a holding device, wherein the holding device pressure cylinder attack, which are also connected to a doctor carrier. For printing, the elastic applicator element is pressed by means of the printing cylinder in the direction of a printing screen and a printing table and then moved by means of a movement of the doctor carrier parallel to the printing table on this or the printing material. The division of the holding device into a plurality of mutually movable holding sections intended to achieve a certain flexibility of the screen printing squeegee. For printing curved surfaces, the squeegee rubber itself is cut according to the contour of the object to be printed.

The invention provides an improved screen printing squeegee and an improved screen printing apparatus which can be flexibly used for printing curved surfaces.

According to the invention, a screen-printing squeegee with an elastic applicator element and a holding device for the applicator element is provided for this purpose, the holding device being divided over the width of the applicator element into a plurality of mutually movable holding sections, in which a leaf spring element is provided which connects the mutually movable holding sections to one another.

By providing the leaf spring element, the screen squeegee in the plane of the applicator element, that is perpendicular to the intended printing direction, comparatively flexible, since the leaf spring in this direction allows a movement of the individual holding sections to each other to a relatively large extent. In contrast, in contrast to the printing direction, the screen-printing squeegee is substantially stiffer, since the leaf-spring element only permits a very limited movement of the individual holding sections relative to one another in this direction. In and against the printing direction, the screen printing squeegee is thus very stiff, so that a precise pressure is made possible. Curved surfaces can thereby be printed with the screen printing squeegee according to the invention, whereby the flexible and resilient design of the screen printing squeegee in the plane of the application element, ie perpendicular to the printing direction, can also be adapted to changing curvatures and a uniform course of the pressing force of the applicator. on the printing screen and the object to be printed.

The screen printing squeegee according to the invention is also suitable for printing three-dimensionally curved surfaces, for example pan-shaped glass panes for motor vehicles. The leaf spring element is designed and arranged such that a spring travel of the individual holding sections is made possible parallel to the plane of the application element, ie perpendicular to the intended printing direction, and a movement of the holding sections in and against the printing direction is largely prevented. The spring action of the leaf spring element at the same time ensures that an excessive movement of the holding sections is prevented from each other and always a continuous, uniform course of decisive for the printing process lower edge of the doctor element is guaranteed.

In a development of the invention, the leaf spring element has a continuous leaf spring extending over at least the length of the doctor blade, from which mounting flanges extend to the individual holding sections.

By means of a continuous leaf spring, which has only one spring leaf in the illustrated embodiment, on the one hand, the desired spring action parallel to the plane of the applicator element, that is perpendicular to the printing direction, and on the other the desired stiffening of the doctor perpendicular to the applicator element, ie in and against the printing direction can be achieved. The provision of mounting flanges allows the unproblematic arrangement of the leaf spring on the holding device or the individual holding sections. Advantageously, seen in the printing direction before and behind the applicator element in each case a leaf spring element provided with retaining flanges. In this way, the leaf spring elements themselves can be made smaller and lighter. are formed, since the spring action and the stiffening of the doctor blade is achieved by means of the two arranged in front of and behind the applicator element leaf spring elements.

In a further development of the invention, the leaf spring is formed from sheet material and has a width which is greater than a thickness of the leaf spring and wherein the leaf spring is oriented so that the width dimension is arranged parallel to the printing direction and the thickness dimension perpendicular to the printing direction and the printing table.

By such an arrangement of the leaf spring is achieved that a spring movement is only possible substantially perpendicular to the printing direction and the printing table, whereas a movement of the individual holding sections to each other in and against the printing direction is largely prevented.

In a further development of the invention, the mounting flanges are formed integrally with the web.

In this way, a structurally simple structure is achieved and the leaf spring element can be assembled and disassembled as a whole in a simple manner.

In a further development of the invention, the leaf spring element is designed as a sheet metal part and the mounting flanges are bent starting from the web.

For example, the leaf spring element can be formed in a simple manner from spring steel and lasered, for example. In this case, the leaf spring consists only of a spring leaf. The problem underlying the invention is also solved by a device for screen printing with a screen printing squeegee according to the invention, in which several, in particular each of the holding sections of Siebdruckrakel a printing cylinder is assigned, wherein the pressure cylinder movable on the one hand with the holding sections and on the other hand with a in and against the printing direction Doctor blade beams are connected, wherein the pressure cylinder acting pressure for at least some of the pressure cylinder is separately adjustable.

In this way, as seen across the width of the screen-printing squeegee, a different pressure can be set on the printing cylinders and in this way can be adjusted over the width of the squeegee, a different contact pressure can be set. This is of great importance if sufficient pressure is to be ensured when printing on curved surfaces, even in the areas of curvature.

In a screen printing device according to the invention, the printing cylinders are fastened on the one hand to a respective holding section and on the other hand to a doctor bar, wherein the printing cylinders are arranged pivotably on the doctor bar and / or on the holding sections in each case about a pivot axis arranged substantially parallel to the printing direction.

In this way, the pressure cylinders can be adjusted so that a force exerted by the printing cylinders on the applicator element substantially always acts perpendicular to the surface to be printed. The pivoting of the impression cylinder can be done during a setting operation, and the impression cylinder can be determined after the adjustment process with respect to the pivot axes. Alternatively, it can also be provided that the printing cylinders can also pivot about the pivot axes during the printing process, for example example, when viewed in the printing direction, the curvature of the object to be printed changes.

In a further development of the invention, a pivot axis is arranged approximately at half the height of the doctor blade beam.

In this way, a stable and geometrically favorable arrangement can be realized.

In a further development of the invention, the pivot axis is located directly above or in the region of the upper edge of the application element.

In this way, a uniform and substantially perpendicular to the pressure edge of the applicator element force application from the printing cylinders in the holding sections or the applicator element is possible.

Further features and advantages of the invention will become apparent from the claims and the following description of preferred embodiments of the invention in conjunction with the drawings. Individual features illustrated in the various drawings and described with reference to the embodiments can be combined in any manner, without exceeding the scope of the invention. In the drawings show:

1 is a representation of a Siebdruckrakel invention in the partially assembled state,

2 is an enlarged view of a portion of the screen printing blade of Fig. 1, Fig. 3 is a partial representation of a screen printing device according to the invention and

4 shows a detail of the screen printing apparatus of FIG. 3.

The illustration of FIG. 1 shows a screen-printing squeegee 10, which has an elastic application element 12 and a holding device 14 for the application element 12. The applicator element 12 is in the form of an elastic and rectangular cross-section material strip. The holding device 14 has a plurality of clip-like holding sections 16, wherein over the width of the applicator element 12 seen a total of nineteen holding portions 16 are provided. A printing direction is indicated by an arrow 18. During a printing operation, the applicator element 12 is thus moved in the printing direction 18 over a printing screen and thereby presses on the printing screen located color through openings in the printing screen on a pressure medium arranged below the printing screen, for example, a curved vehicle window. The width of the applicator element 12 is perpendicular to the printing direction 18 and parallel to a printing table, not shown, the length of the applicator element 12 parallel to the printing direction 18. The applicator element 12 thus has a width which is substantially greater than its length.

The holding portions 16 are each formed like a clip and engage over an upper edge of the elastic applicator element 12. However, the individual holding portions 16 are formed as separate from each other retaining clips, so that the individual holding portions 16 are movable relative to each other.

The holding sections 16 are connected both on a front side of the screen-printing squeegee 10 and on a rear side of the screen-printing squeegee 10, each with a leaf-spring element 20, 22. The leaf spring elements 20, 22 are connected to the retaining clips of the holding portions 16 above the applicator element 12.

The two leaf spring elements 20, 21 are each integrally formed as a sheet metal bent part and each have a leaf spring 24, 26 and a plurality of bent from the leaf spring 24 mounting flanges 28, 30. Each of the holding portions 16 is associated with a respective mounting flange 28, 30 and the mounting flanges 28 are each secured by means of two bolts 32 to the retaining portions 16 formed as retaining clips.

As can be seen in Fig. 1, a width of the leaf spring 24 is greater than a thickness of the leaf spring 24. The thickness direction is perpendicular to the printing direction 18 and a printing table, not shown, the width direction parallel to the printing direction 18. The leaf spring 24 is thus formed in the form of a single spring leaf and allows a spring movement substantially only perpendicular to the printing direction 18 and perpendicular to a printing table, not shown, in Fig. 1 in the thickness direction of the spring leaf and thus from bottom to top and vice versa. In and against the direction of pressure 18, the leaf spring is much stiffer due to their width significantly greater than the thickness and thus largely prevents movement of the individual holding portions 16 in and against the printing direction 18. The width of the leaf spring 24 is about five to ten times greater than that Thickness of the leaf spring 24, wherein the ratio of width to thickness and the spring stiffness of the leaf spring can be adapted to the intended application. Optionally, a plurality of spring leaves may be provided which have different lengths to achieve the desired spring action.

During a printing operation, the individual holding sections 16 can thus be perpendicular to the printing direction 18 and perpendicular to the printing direction. move table relative to each other and in this way the elastic applicator element 12 can be deformed so that its pressure edge 34 is curved and can be adapted in this way to the contour of an object to be printed. Nevertheless, a deflection of the applicator element 12 and especially the pressure edge 34 in and against the printing direction 18 is largely avoided, since in and against the printing direction 18, a movement of the individual holding portions 16 with each other by the two leaf springs 24, 26 is largely prevented.

The screen printing squeegee according to the invention is thus very flexible perpendicular to the printing direction 18 and perpendicular to the printing table and can be adapted to curvatures of one object to be printed. On the other hand, in and against the printing direction, the screen-printing squeegee 10 is very stiff and thus enables a very precise printing process.

In the illustration of FIG. 2, an enlarged view of a portion of the screen-printing squeegee 10 can be seen. Shown are only two of the holding portions 16 completely and two further holding portions 16 partially. As has already been explained with reference to FIG. 1, the holding sections 16 are each designed as holding clamps and embrace the upper edge of the elastic applicator element 12. The legs of these holding clamps are movable toward one another for a clamping operation in order to clamp the elastic applicator element 12 securely.

The leaf spring element 20 has the leaf spring 24, from which the mounting flanges 28 extend. The mounting flanges 28 are then respectively secured to the legs of the retaining clips of the holding portions 16, wherein the attachment of the mounting flanges 28 by means of the bolts 32 on the holding portions 16 above an upper edge of the elastic applicator element 12. The leaf spring 24, however, is approximately halfway up the applicator element 12 and wa at the height of the free end of the legs of the retaining clips of the holding portions 16 is arranged.

The holding sections 16 are profiled at their upper end facing away from the applicator element 12 in the form of retaining grooves, so that they can be clamped in clamping jaws 56 of a squeegee holder, see FIG. 4.

The illustration of FIG. 3 shows a screen printing device 40 according to the invention with a screen printing doctor blade 10 according to the invention from the front, thus counter to the printing direction 18 in FIG. 1. The leaf-spring element of the screen-printing squeegee 10 has a slightly different design than in the case of the embodiment of FIG. 1, but the representation of FIG. 3 serves essentially to clarify the structure of the screen-printing device 40 according to the invention.

Each of the holding portions 16 is assigned a respective printing cylinder 42, 48. The pressure cylinders 42, 48 are arranged on the one hand on the holding portions 16 and on the other hand on receiving elements 44, wherein the receiving elements 44 are arranged displaceably on a doctor bar 46.

As can be seen in the illustration of FIG. 3, the printing cylinders 42 are partially deflected from their vertical position to the doctor bar 46. The impression cylinders 42, with the exception of the two central impression cylinders 48, are pivotable about a respective pivot axis 52, 54 both relative to the application element 12 on the doctor blade 46 and relative to the holding sections 16. The pivot axes 52, 54 are all parallel to the printing direction 18, in Fig. 3 so perpendicular to the plane. As can be seen in FIG. 3, an introduction of force by means of the pressure cylinder 42 can thereby be achieved over the entire width of the screen-printing squeegee 10 approximately perpendicular to its pressure edge 34 take place, which rests during a printing operation on a printing screen, not shown, which in turn rests on a printing material, not shown, to be printed, which in turn is located on a printing table 50. In the region of the left and right end of the screen printing blade 10 it can be seen that the pressure introduction is not exactly perpendicular to the pressure edge 34. An improvement is possible in that the position of the pivot axis 52 is further displaced in the direction of the pressure edge 34. Advantageously, the pivot axis 52, with which the pressure cylinders 42 are arranged pivotably on the holding portions 16, in the region of the upper edge of the elastic applicator element 12 or even below the upper edge of the applicator element 12 is arranged.

In a manner not shown, the doctor angle can be adjusted, ie an angle between the applicator element 12 and the surface to be printed. This is realized by a curved link guide on the doctor blade receptacle between the pivot axis 52 and the clamping jaws 56.

The representation of FIG. 4 shows one of the printing cylinders 42, wherein the screen printing squeegee 10 is not shown in Fig. 4. It can be seen that a pivot axis 52, about which the pressure cylinder 42 is pivotable relative to the receiving element 44, is arranged at half the height of the doctor beam 46. The receiving element 44 is provided with two clamping screws and can be moved along the doctor blade 46. The movement about the pivot axis 54 and about the pivot axis 52 can be blocked, so that the pressure cylinders 42 are pivoted about the pivot axes 52, 54 in a setting and then blocked. Alternatively, the pivoting of the impression cylinder 42 about the pivot axes 52, 54 may also be enabled during a printing operation to allow adaptation of the screen printing blade 10 to changing curvatures of the article 50 to be printed. This is for example advantageous if the object to be printed 50 is a trough-like car window whose curvature changes perpendicular to the printing direction and also in and against the printing direction over length.

At the lower end of the printing cylinder 42, a doctor blade holder with clamping jaws 56 and provided with a clamping screw, with the clamping jaws 56 then respectively the holding portions 16, see Fig. 1, Fig. 2, are clamped. The Siebdruckrakel 10 is thereby mounted in a simple manner and dismountable.

Claims

claims

Silkscreen with an elastic applicator element (12) and a holding device (14) for the applicator element (12), wherein the holding device (14) across the width of the applicator element (12) seen in a plurality of mutually movable holding portions (16) is divided, characterized in that a leaf spring element (20, 22) is provided which connects the mutually movable holding sections (16) to one another.

Screen-printing squeegee according to claim 1, characterized in that the leaf spring element (20, 22) has a continuous leaf spring (24, 26) extending at least over the width of the applicator element (12) from which mounting flanges (28, 30) extend to the extending individual holding portions (16).

Screen printing squeegee according to claim 1 or 2, characterized in that the leaf spring (24, 26) is formed from sheet material, wherein a thickness of the leaf spring perpendicular to the printing direction (18) is smaller than a width of the spring sheet parallel to the printing direction (18), so that a spring movement of the leaf spring (24, 26) substantially only perpendicular to the printing direction (18) and perpendicular to the printing table (50) is made possible.

Screen-printing squeegee according to one of the preceding claims, characterized in that the fastening flanges (28, 30) are formed integrally with the leaf spring (24, 26).

Screen printing squeegee according to claim 4, characterized in that the leaf spring element (20, 22) is formed as a sheet metal part and the mounting flanges (28, 30) are bent away from the leaf spring (24, 26).

6. screen printing device with a screen printing blade according to any one of the preceding claims, characterized in that each holding sections (16) is associated with a pressure cylinder (42, 48), wherein the pressure cylinder (42, 48) acting pressure for at least some of the plurality of pressure cylinder (42 , 48) is independently adjustable.

7. screen printing device, in particular according to claim 6, with a

Silkscreen with an elastic applicator element (12) and a holding device (14) for the applicator element (12), wherein the holding device (14) across the width of the applicator element (12) seen in a plurality of mutually movable holding portions (16) is divided, characterized in that the printing cylinders (42, 48) are fastened on the one hand to a respective holding section (16) and on the other hand to a squeegee bar (46), wherein the printing cylinders (42) at least partially on the squeegee bar (46) and / or on the respective holding section (16 ) are arranged pivotably about a pivot axis (52, 54) arranged parallel to the pressure direction (18).

8. screen printing apparatus according to claim 7, characterized in that the pivot axis (52) is arranged approximately halfway up the squeegee beam (46).

9. screen printing apparatus according to claim 7 or 8, characterized in that the pivot axis (52) is arranged directly above or in the region of an upper edge of the elastic applicator element (12).