Doctor blade device

Abstract

The invention below relates to a doctor blade device with an elongated doctor blade intended to operate continuously against a roll surface (2) and/or a cylinder surface (20) during scraping or wiping off material (IB) on the surface (20), which doctor blade device (5) comprises a carrier beam (10) adapted to the length of the roll surface or cylinder surface, which carrier beam has a clamping arrangement (4) for the positioning of a carrier part (3), arranged, in a groove in the longitudinal direction, to slidably carry the doctor blade (6), wherein the carrier part (3) comprises a carrier blade (30), a lip means (14) arranged at the carrier blade (30) and a spacer element (12) arranged between the lip means (14) and the carrier blade, wherein the carrier blade (30), the lip means (14), and the spacer element (12) are arranged, along a first long side edge of the carrier blade (30) between them, to form said groove (15) for slidable positioning in the longitudinal direction of the doctor blade (6) by support of the carrier blade (30), the lip (14), and the spacer element (12).

Claims

1. A method for creping off a paper web from a roll surfaces or cylinder surfaces comprising: providing a doctor blade device having an elongated doctor blade configured to operate continuously against said roll surface and/or a cylinder surface, which doctor blade device comprises a carrier beam adapted to the length of the roll surface or cylinder surface, which carrier beam has a clamping arrangement for the positioning of a carrier part, arranged to slidably carry the doctor blade in a groove in the longitudinal direction, wherein the carrier part comprises a carrier blade, a lip means arranged at said carrier blade and a spacer element arranged between said lip means and said carrier blade, wherein the carrier blade, the lip means, and the spacer element are arranged to form between them, said groove along a first long side edge of the carrier blade, to facilitate slidable positioning in the longitudinal direction of the doctor blade by support of the carrier blade; continuously feeding said doctor blade longitudinally in said groove while creping off a paper web from said roll surface and/or a cylinder surface; and providing said carrier blade with a plurality of transverse relief slots emanating from a second long side edge of the carrier blade and said lip means is divided into a number of successive lip parts.

2. The method for creping off a paper web according to claim 1, wherein said carrier beam is provided with a first chamber arranged to accommodate a long side of the carrier blade, the second long side of which protrudes out of said chamber.

3. The method for creping off a paper web according to claim 2, wherein said chamber has a smallest opening in the longitudinal direction, which opening is larger than the thickness of the carrier blade, wherein the chamber is so designed that it admits a certain tilting of the carrier blade in the recess while the carrier blade rests against said bottom.

4. The method for creping off a paper web according to claim 2, wherein said chamber has a smallest opening in the longitudinal direction, which opening is larger than the thickness of the carrier blade, and said second long side edge of the carrier blade rests against the bottom of said chamber, wherein the chamber is so designed that it admits a certain tilting of the carrier blade in the recess while the carrier blade rests against said bottom.

5. The method for creping off a paper web according to claim 1, wherein the spacer element is a separate part with respect to the lip means.

6. The method for creping off a paper web according to claim 5, wherein said spacer element is divided into a number of successive spacer element parts.

7. The method for creping off a paper web according to claim 1, wherein the lip means is divided into a number of successive lip parts.

8. The method for creping off a paper web according to claim 7, wherein the number of spacer element parts is larger than the number of lip parts.

9. The method for creping off a paper web according to claim 1, wherein the carrier blade has a plurality of transverse relief slots emanating from a second long side edge of the carrier blade.

10. The method for creping off a paper web according to claim 1, wherein the doctor blade has a width, which is 5% to 50% of the width of the carrier blade.

11. The method for creping off a paper web according to claim 1, wherein the doctor blade has a width, which is 10% to 30% of the width of the carrier blade.

12. The method for creping off a paper web according to claim 10, wherein the carrier beam comprises a second chamber formed between a second lip and a third lip, and a press blade extends from a bottom in said second chamber out between the second lip and the third lip to a line abutment against the carrier blade.

13. The method for creping off a paper web according to claim 10, wherein the carrier beam comprises a second chamber formed between a second lip and a third lip, and a press blade extends from a bottom in said second chamber out between the second lip and the third lip to a line abutment against the carrier blade, in connection to the bottom of the groove for the doctor blade.

14. The method for creping off a paper web according to claim 1, wherein the doctor blade has a length being several times larger than the length of the roll surface or the cylinder surface, against which the doctor blade will operate.

15. The method for creping off a paper web according to claim 1, wherein the doctor blade has a length being several times larger than the length of the roll surface or the cylinder surface, against which the doctor blade will operate and the ends of the doctor blade are joined to each other for the formation of a continuous doctor blade band.

16. The method for creping off a paper web according to claim 1, wherein the doctor blade has a length being several times larger than the length of the roll surface or the cylinder surface, against which the doctor blade will operate, wherein the ends of the doctor blade are joined to each other for the formation of a continuous doctor blade band.

17. The method for creping off a paper web according to claim 16, wherein at least one long side edge of the doctor blade is ground to an angle of about 60° to about 90° in relation to the adjacent sides of the doctor blade in order to give a desired angle of about 80° to about 95° between the ground surface and a tangent to the roll surface, or the cylinder surface in the abutment point of the roll surface, or the cylinder surface.

18. The method for creping off a paper web according to claim 16, wherein at least one long side edge of the doctor blade is ground to an angle of about 60° to about 90° in relation to the adjacent sides of the doctor blade in order to give a desired angle of about 80° to about 95° between the ground surface and a tangent to the roll surface, or the cylinder surface in the abutment point of the roll surface, or the cylinder surface, wherein both long side edges of the doctor blade are ground such that the doctor blade band has a rotation-symmetric cross-section, and that one band end at the joining of the ends is turned half a turn in relation to the other one for the formation of a Mobious-band with only one side and only one long side edge.

19. The method for creping off a paper web according to claim 1, wherein the carrier blade has a plurality of transverse relief slots emanating from a second long side edge of the carrier blade, and the transverse relief slots are evenly distributed along the length of the carrier blade.

20. The method for creping off a paper web according to claim 1, wherein the doctor blade has a width, which is 10% to 30% of the width of the carrier blade.

Description

BRIEF DESCRIPTION OF THE ENCLOSED DRAWINGS

(1) Below the invention will be described more in detail with reference to the preferred embodiments and the enclosed drawings, of which:

(2) FIG. 1 is a schematic side view of a known creping doctor blade (US 2010/0032112 (Eriksson)), which view shows the principles thereof.

(3) FIG. 2 is a schematic side view of a creping doctor blade comprising a doctor blade device according to the invention with a doctor blade and a holder, which is mounted in a known type of traditional carrier beams and comprises a carrier blade, a lip means, and an intermittent spacer element and is held in a carrier beam, which also holds a press blade abutting against the carrier blade.

(4) FIG. 3 is a plan view of a part of a preferred embodiment of the holder.

(5) FIG. 4 is an enlarged cross-sectional view of the doctor blade and adjacent parts of the holder taken along the line IV-IV in FIG. 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(6) FIG. 1 shows a side view of a creping doctor blade device 5 according to US 2010/0032112 (Eriksson), by means of which a soft paper web 1B adhered to the jacket surface 20 of a Yankee cylinder 2 is creped off from the jacket surface 20 during the formation of a creped soft paper web 1C. The creping doctor blade device 5 is pivotally suspended in a securing part 8, here preferably in the form of axle stubs. Through the rotary motion, the creping doctor blade device 5 can be positioned in an operation position and a disconnected inactive position. The creping doctor blade device comprises a carrier beam 10 consisting of an elongated body with securing means (e.g. circular recesses) intended for said axle studs. There is a heel 77 at the upper portion of the body, in which heel a holder part 3 is clamped with a holding arrangement 4. A doctor blade 6 (which can also be designated as a scraping blade) is slidably/movably arranged in a gap in the holder part 3. With the aim to be able to use this construction optimally there is a pivotable link 34, here in the form of a waist constituting a pivotal, resilient link. By pivoting the portion above the pivot link 34, the doctor blade 6 can be given different pressures and/or angles β for its abutment against the jacket surface. The result of the creping operation, i.e. i.a. the thickness and macro-structure of the creped paper web 1C, is, however, not in the first place controlled by the angle β but by the so called pressure—or shock angle between the up-stream segment of a tangent to the mantel surface 20 in the abutment point 62 of the doctor blade 6 and the abutment—or shock surface 60 for the arriving web 1B.

(7) Further, a press device 9 is shown, consisting of an elongated (or in the longitudinal direction divided/sectioned) body and which approximately in the middle of said body is pivotally arranged about a pivot point 7. At the upper end of the press body there is a press means 91 (which can be elongated or sectioned), which with its end abuts against the holder part 3 along a line above said link point 34, so that a pressure by means of the press means 91 can influence the press force of the doctor blade 6. The press force can be applied by one press means 96, or more, (preferably a flexible, inflatable hose) in order to control the abutment pressure against the jacket surface 20 at its contact line 62.

(8) FIG. 2 shows a view from the side of an embodiment according to the invention. An important difference in relation to prior art shown in FIG. 1 is that the invention can use a holder device 8 and a carrier beam 10 in accordance with a conventional, generally used embodiment. FIG. 2 shows a type of conventional holder devices 8 with a conventional carrier beam 10 and a conventional press arrangement 9, at which a doctor blade arrangement 3, 6, 12, 14 is arranged according to a preferred embodiment of the invention.

(9) The doctor blade arrangement according to the invention comprises a holder part 3 in the form of a carrier blade 30, at the upper end of which a movable wear part 6 is arranged. The wear part 6 is movably arranged in a gap 15 (see FIG. 4), which is arranged between a lip means 14 and the upper end of the carrier blade. Spacer elements 12 are arranged between the lip means and the carrier blade 30 in order to create a desired gap 15, which enables a steady provision of the wear part 6 but with enough space in the gap 15 to be able to displace the wear part 6 in its longitudinal direction in a desired way. The carrier blade 30 is arranged in a first chamber 100, which is arranged between a first lip 102 and a second lip 103 in the carrier beam 10, which lips are preferably designed in accordance with conventional doctor blade technique. According to a preferred embodiment of the invention, the carrier blade 30 is designed such that a traditional doctor blade can be used as initial material, which implies many advantages also from a cost point. Thus, the carrier blade 30 is suitably made of steel and suitably has a thickness T in the region of 0.5 mm to 3 mm and a width B in the region of 75 mm to 150 mm. The carrier blade 30 abuts with its lower end 32 against the bottom 101 of the chamber 100 and is during operation with its lower end 32 clamped in an outer corner A of the bottom, which corner A then functions as a kind of pivot point for the carrier blade 30 and which enables that the holder blade can flex inside the space in the first chamber 100 and in the gap D formed at the top between the lips 102, 103 for abutment by a certain angle y. Suitably, the chamber 100 has a width essentially exceeding the thickness t of the holder blade 30. Further, it can be seen that the carrier beam 10 is provided with a second chamber 104, inside which a press blade 91 is arranged as well as an equalizing means 96 being a part of a press device 9, also in accordance with prior art. By means of the equalizing means 96 in interaction with a third lip 105, the press force F of the press blade 91 can be adjusted in a manner known per se and hence exert a desired press force on the holder part 3 and hence the wear part 6 in abutment against the surface 20 of the roll 2. During operation, the wear part 6 can be moved either at certain intervals or continuously in order to renew the wear surface 60 with the wear part 6. The wear part is suitably made of steel with a thickness t in the region of 0.4 mm to 1.5 mm and a width B in the region of 10 mm to 30 mm.

(10) FIG. 3 shows a part of a carrier blade 30 according to the invention seen from the front. As can be seen, the lip means 14 is suitably arranged in the form of a plurality of separate elements 14′, which are attached to the carrier blade 30 by means of screw elements 13. In the left part of FIG. 3 it is shown that circular washers 12′, preferably standard washers of stainless steel, are preferably used as spacer elements 12 to achieve a desired gap S between the carrier blade 30 and the lip means 14 to accommodate the wear part 6 without clamping. At a position nearer the middle of FIG. 3 it is indicated that the spacer element 12 can also have another design, for instance in the form of rectangular washers 12″. It is realized that that spacer element 12 can, of course, also consist of an elongated continuous unit, either in itself or integrated with the lip means 14.

(11) FIG. 4 shows a cross-section of the upper part of a carrier blade 3 with a wear part 6, as is indicated in FIG. 3. As can be seen, the wear part protrudes a distance enough down into the gap 15 formed between the lip means 14 and the upper part 31 of the carrier blade in order to obtain support enough for the abutment against the roll 2. Further, it is shown that the lip means 14 with its upper end 140 is arranged at a distance X (suitably about 3 mm to 15 mm) below the upper end 31 of the carrier blade in order to be able to create space enough between the wear part 6 and the roll surface to arrange the wear part 6 at a desired angle β in relation to the roll surface 20 and that, with the same aim, the upper part of the lip means is advantageously provided with a bevel 14A. Further, it is shown that the washer 12 is advantageously arranged by means of screws 13 having lock threads 13A or is in another way safely secured in the carrier blade 3. Preferably, the screws 13 are hard clamped against the washer 12, which can further guarantee safe anchorage. A possible modification is to provide a circular washer 12′, which by not being clamped against the carrier blade 3 can be arranged, so that is freely rotatable about the screw 13, whereby a displacement of the wear part 6 can be further facilitated.