DOCTOR BLADE SYSTEM

Abstract

A doctor blade system of a printing machine comprises a doctor blade (12), a blade support (14) and a clamping element (16), wherein the doctor blade (12) is arranged at a contact surface (24) on a front side (20) of the blade support (14) and pressed against the contact surface (24) by a pressing area (34) of the clamping element (16). The clamping element (16) has a bearing surface (40) arranged at a backside (27) of the blade support (14).

Claims

1. A doctor blade system of a printing machine, the doctor blade system comprising: a doctor blade; a blade support; and a clamping element, wherein the doctor blade is arranged at a contact surface on a front side of the blade support and pressed against the contact surface by a pressing area of the clamping element, and wherein the clamping element has a bearing surface arranged at and pressing against a backside of the blade support.

2. The doctor blade system according to claim 1, wherein the contact surface is part of a recess of the blade support.

3. The doctor blade system according to claim 2, wherein the pressing area of the clamping element is part of a protrusion which engages into the recess.

4. The doctor blade system according to claim 1, wherein a surface of the pressing area is parallel to an extension direction of the doctor blade.

5. The doctor blade system according to claim 1, wherein the bearing surface of the clamping element is interacting with a retaining mechanism at the backside of the blade support.

6. The doctor blade system according to claim 5, wherein the retaining mechanism comprises a sheet metal spring or a compression spring.

7. The doctor blade system according to claim 5, wherein the bearing surface of the clamping element is interacting with the retaining mechanism by transfer element arranged between the retaining mechanism and the bearing surface of the clamping element.

8. The doctor blade system according to claim 1, wherein the bearing surface is a surface of a lug of the clamping element.

9. The doctor blade system according to claim 1, wherein the doctor blade system has two doctor blades which are each secured by a clamping element.

10. The doctor blade system according to claim 9, wherein the doctor blade system (10) is a chamber doctor blade system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Further advantages and features will become apparent from the following description of the invention and from the appended figures which show non-limiting exemplary embodiments of the invention and in which:

[0044] FIG. 1 shows a partial explosive view of a cut through a first embodiment of a doctor blade system according to the invention;

[0045] FIG. 2 shows the assembled doctor blade system of FIG. 1 in a printing machine; and

[0046] FIG. 3 a detail of a cut through a second embodiment of the doctor blade system according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0047] FIG. 1 shows a partial explosive view of a cut through a doctor blade system 10 according to the invention.

[0048] The doctor blade system 10 comprises two doctor blades 12, a blade support 14 and two clamping elements 16.

[0049] The blade support 14 has a cavity 18 at a front side 20.

[0050] The blade support 14 has two contact surfaces 24 into which the doctor blades 12 are placed when the doctor blade system 10 is assembled.

[0051] The contact surfaces 24 are part of recesses 25, which form a step towards side surfaces 26 of the blade support 14.

[0052] At a backside 27, the blade support 14 has two retaining mechanisms 30. The retaining mechanisms 30 comprise sheet metal springs 28, which are fixed to the blade support 14 by screws 32.

[0053] In the shown embodiment, the clamping elements 16 are spring clips of a size suitable to extend from the front side 20 over the side surface 26 to the backside 27.

[0054] The clamping elements 16 each have a pressing area 34 on a protrusion 36, which in the shown embodiment are formed in a first end section of the clamping element 16. The protrusion 36 can engage in the recesses 25 on the front side 20 of the blade support 14.

[0055] Further, the clamping elements 16 each have a lug 38, which in the shown embodiment are formed in a second end section of the clamping element 16.

[0056] To assemble the doctor blade system 10, the doctor blades 12 are each placed into one of the recesses 25 on the front side 20 of the blade support 14, so that the doctor blades 12 are in contact with the stop of the respective recess 25.

[0057] Then, the protrusion 36 of the clamping element 16 is placed on top of the respective doctor blade 12 and the lug 38 is clamped on the sheet metal spring 28 of the retaining mechanism 30.

[0058] With other words, the first end section of the clamping element 16 is placed on the front side 20 and the second end section is used to fasten the clamping element 16 around the blade support 14.

[0059] Due to the tension of the clamping element 16, the pressing area 34 of the protrusion 36 presses on the doctor blade 12 so that the doctor blade 12 is pressed against the contact surface 24 of the blade support 14.

[0060] At the same time, the lug 38 arranged at the backside 27 of the blade support presses with a bearing surface 40 on the sheet metal spring 28.

[0061] Therefore, the clamping elements 16 is securely fixed in its position around the blade support 14.

[0062] In FIG. 2, the assembled doctor blade system 10 is shown as it is used in a printing machine.

[0063] The doctor blade system 10 is pressed against a printing cylinder 42 of the printing machine. The printing cylinder 42 is an anilox roll in the shown embodiment. Accordingly, the printing machine is a flexographic printing unit.

[0064] The anilox roll rotates in the direction illustrated in FIG. 2 by the arrow A and takes up ink from an ink reservoir 44 into cells engraved in the surface of the anilox roll during its rotation.

[0065] The ink reservoir 44 is formed between the anilox roll, the doctor blades 12 and the surface of the cavity 18 of the blade support 14. Accordingly, the doctor blade system 10 is a chamber doctor blade system in the shown embodiment.

[0066] The blade support 14 can have an ink inlet and ink outlet (not shown) which can supply and remove ink from the ink reservoir 44, respectively.

[0067] The doctor blades 12 are used to scrape of excess ink from the surface of the anilox roll.

[0068] As is best seen in FIG. 2, the protrusions 36 of the clamping elements 16 extend over the full length of the recesses 25 on the front side 20 of the blade support 14.

[0069] Further, the pressing areas 34 on the protrusions 36 are parallel to the respective contact surfaces 24 of the recesses. Accordingly, the clamping element 16 is pressing the respective doctor blade 12 onto the contact surface 24 with a force perpendicular to the contact surface 24.

[0070] The contact surfaces 24 are inclined relative to the printing cylinder 42, wherein the inclination angles differ between the two contact surfaces 24 to allow for a desired contact angle between the respective doctor blade 12 and the printing cylinder 42.

[0071] During operation of the printing machine, the doctor blades 12 wear down due to the friction between the rotating printing cylinder 42 and the doctor blades 12. In addition, excess ink can adhere to the doctor blades 12.

[0072] Therefore, the doctor blade system 10 needs to be de-assembled after some time to exchange the doctor blades 12 and/or to clean the doctor blades 12 and the blade support 14.

[0073] For this, an operator (not shown) of the printing machine can press on the sheet metal spring 28 so that the sheet metal spring 28 bends towards the blade support 14.

[0074] As a result, the lug 38 is not any more supported on the retaining mechanism 30 and the clamping element 16 can easily be removed so that the doctor blades 12 can be exchanged and/or the blade support 14, especially the cavity 18, can be cleaned.

[0075] The embodiment shown in FIGS. 1 and 2 comprise two doctor blades 12. In principle, the doctor blade system 10 could also have a single or more than two doctor blades 12. In this case, the doctor blade system 10 preferably has a clamping element 16 and a retaining mechanism 30 for each of the doctor blades 12.

[0076] In FIG. 3, a second embodiment of the doctor blade system 10 is shown, wherein only part of the doctor blade system 10 is shown, analogue to the lower half of the doctor blade system 10 as shown in FIG. 2.

[0077] The second embodiment essentially corresponds to the first embodiment so that only differences will be discussed below. Same parts are denoted with the same reference numerals and reference is given to the explanations given above.

[0078] In the second embodiment, a different retaining mechanism 30 is used, which comprises a compression spring 46 acting on a transfer element 48 with a counter-directed force F.sub.KL.

[0079] The compression spring 46 is arranged in a groove 50 on the backside 27 of the blade support 14.

[0080] The transfer element 48 interacts with the bearing surface 40 of the lug 38 of the clamping element 16.

[0081] To release the clamping element 16, an operator can press manually or with a tool 52 on the transfer element 48 with a force F.sub.E sufficient to compress the compression spring 46.