WO1996015320A1 - Coating device - Google Patents

Abstract

In the proposed coating device (100), the actual wiping blade (60) is formed along the outer circumference of a non-rotating wiping blade tube (13) which is held along its length by a non-rotating carrier (14) which leaves a gap between itself and the inner circumference (15) of the wiping blade tube (13). Across the working width in the intermediate cavity between the inner circumference (15) of the wiping blade tube (13) and the carrier (14) on the side of the roller (3) which co-operates with the wiping blade (60) and on the opposite side, is arranged in each case a closed hose (40, 50) which can be inflated using a fluid pressurized medium. The stops on the roller (3) and wiping blade tube (13) in the lateral roller housings lie in the same, in relation to the axes (W, R) of the roller (3) and wiping blade tube (13) vertical, planes (5, 6). This arrangement optimises the alignment of the trajectory of the wiper blade edge (45) with that of the opposite surface line of the roller (3).

Description

 Coating device

The invention relates to a coating device of the type corresponding to the preamble of claim 1.

Coating devices of this type are used to uniformly spread out a thin coating applied to a running web of material. By "web" should be understood web-like substrates of all kinds, e.g. Paper and cardboard webs, nonwovens, woven or other textile webs, plastic or metal foils. Very high demands are often placed on the uniformity of the "stroke". This is particularly the case in the paper sector because the thickness of the coating, which varies across the width of the web, is noticeable in the quality of the paper and its further processing, in particular its printability. The uniformity of the coating is made more difficult by the large width of the paper webs of 8 and more meters.

The invention is therefore based on the object of improving an overall coating device with regard to the uniformity of the stroke that can be achieved.

This object is achieved by the invention reproduced in claim 1.

The support structure supporting the squeegee is thus designed like a hydraulically internally supported roller - 2 - which, however, does not rotate the roller or doctor tube. However, this makes it possible to precisely influence the position of the doctor blade edge relative to the web clinging to the roller. With the large widths of paper webs, for example, even the low contact pressures of a doctor blade edge and in particular the weight of the doctor blade and the roller lead to deviations in the shape of the roller from a straight cylinder. Straightness is not even important. Dimensional for a coating thickness that is uniform over the web width is an optimal active adaptation to the course of the substrate, ie generally to the course of the wear of a goods by means of a roller. This can be brought about by corresponding actuation of the hydraulic support device.

The fact that the outer supports of the doctor tube, axially seen, should lie at the same point as the bearing centers of the roller has the purpose of being able to bring about the same bending lines, so that the edge of the doctor blade follows the course of the opposite jacket limes of the circumference of the The roller fits perfectly.

It is already known per se to support a doctor blade via a fluid pressure medium in order to switch off the deflection along the length of the doctor blade (DE 21 10 492 A1). DE 29 35 413 C2 shows a hydraulically internally supported doctor tube, which thus forms the doctor blade itself and serves to even out a foam application applied to a rotating roller, which then runs in between the rotating roller circumference and a running web.

Wo 82/00165 shows a pair of rollers in which the support of a tubular roller, viewed axially, is located at the same location as the bearing center of a cross roller. Here, of course, the roller tube rotates, while the invention is a fixed arrangement.

The hydraulic support device can be in the Claim 2 described be designed. The opposing support devices result in a vibration-damped support of the doctor tube on both sides, the deflection being determined by the pressure difference. The effective level should be the level of the contact pressure of the doctor blade, when interacting with a counter roller generally the connection level of the axes of the counter roller and the doctor tube.

The doctor blade also experiences entraining forces through the material web, which stress the doctor tube perpendicular to the active plane. Such forces can be counteracted with the configuration according to claim 3.

The fluid pressure medium can be tempered, i.e. be heatable or coolable so that the doctor blade can be given a certain temperature (claim 4).

However, this effect can also be achieved by means of a separate temperature-controlled heat transfer medium

5).

The hydraulic support device can be designed in a first possible version according to claim 6.

Alternative designs of the hydraulic support device are the subject of claims 7 and 8.

The feed lines are expediently designed according to claim 10.

An important feature is the subject of claim 11.

The Ξ module is usually fixed because both the roller and the doctor tube are made of steel. The area moment of inertia can, however, be changed by appropriate shaping, ie dimensioning the cross sections depending on their radial position. The feature of claim 11 makes it possible to respond to a change in the roll nip force by adjusting the pressure of the fluid medium, that is to say the oil or the compressed air, without the gap height at the squeegee edge suffering as a result. The one ai set via a corresponding facility te gap remains over its length, or over its extent transverse to the web.

The feature of claim 12 ensures proper radial positioning of the doctor tube relative to the roller.

The positioning can be made adjustable according to claim 13.

According to claim 14, the thickness of the applied coating can be measured continuously and the gap height can be controlled by a drive and a desired value of the thickness can be maintained automatically by closed-loop control. It is not excluded to mount the actual doctor blade as a separate part on the outer circumference of the doctor tube.

In the preferred embodiment according to claim 15, however, the doctor blade is integrally connected to the doctor tube, which can be achieved, for example, by machining the circumference of the doctor tube according to claim 16 and can be carried out in detail according to claim 17 or 18.

Exemplary embodiments of the invention are shown in the drawing.

1 shows a front view of a coating device, partly in a section through the axes of the roller or of the doctor tube;

FIG. 2 shows a view according to FIG. 1 from the left; Fig. 3 shows a cross section along the line III-III in Fig. 1;

Fig. 4 shows a section along the line IV-IV in Fig. 1st

5 shows a schematic front view of a further embodiment of a coating device;

Fig. 6 shows a cross section along the line VI-VI in Fig. 5;

7 shows a front view of a third embodiment;

Fig. 8 shows a cross section along the line VIII- VIII in Fig. 7?

FIG. 9 shows a cross section corresponding to FIG. 6 or 8 through yet another embodiment.

The coating device designated 100 as a whole in FIG. 1 comprises two lateral roller stands 1, 2, in which a roller 3 is mounted on its roller journals 3 'in lateral bearings 4, the central planes of which in planes 5 and 5 perpendicular to the roller axis W. 6 are located. The roller 3 projects with its pin 3 'on the left side in FIG. 1 at 3 "laterally above the roller stand 1 and there has a wedge 23 arranged in a groove, which can serve as a drive connection. The bearings 4 are in bearing bodies 7 2, which have an approximately square plan in a plane perpendicular to the roller axis W. The bearing body 7 bears against an upper horizontal boundary 8 of a rectangular section of the machine stand 1 or 2, and a horizontal boundary surface 9 lies opposite it On this boundary surface 9 there is a pneumatic pressure element 11, which acts from below against the bearing body 12 of a doctor tube, designated as a whole by 13.

The doctor tube 13 extends across the width of the web 10 and beyond into the roller stand 1, 2, where it is held in the bearing bodies 12. The length of the squeegee tube 13 is penetrated by a carrier 14, which leaves all around distance from the inner circumference 15 of the squeegee tube 13 and is supported at the ends by spherical surface bearings 16 on the inner circumference of the squeegee tube 13. The doctor tube 13 is seated in this area in bores 17 of the bearing body 12, which has a continuous radial slot 18 at one point and can be clamped there by means of a clamping screw 19 around the outer circumference 20 of the doctor tube 13. A screw 21, which is arranged on the outside of the spherical surface bearing 16 and is radially screwed into the carrier 14, engages with its head in a corresponding recess 22 of a cover plate 23 screwed onto the end face of the doctor tube 12 and ensures that side rotational fixation of the carrier 14 and the doctor tube 13th

The bearing body 12 of the doctor tube 13 is supported by a wedge 30 from below against the underside 31 of the bearing body 7. The wedge 30 has a flat upper side and at approximately equal distances from the connecting plane E of the axes of the roller 3 and the doctor tube 13 there are supporting zones 34, 35 of approximately semicircular cross section, which are in a corresponding semicircular recess 33 in the bearing body 12 concerns. The bearing body 12 is not firmly connected to the bearing stand 1 or 2, but has a certain slight mobility, which results in a change in the distance between the bearing bodies 7 and 12 in accordance with the insertion depth of the wedge 30, which is achieved by means of the screw spindle 32 can be regulated. The wedge 30 can, for example, have a wedge angle of 0.5 °. By actuating the screw spindle 32, the spacing of the laser bodies 7 and 12 can be set sensitively. The pneumatic pressure elements 11 always keep the bearing body 12 in contact with the underside 31 of the bearing body 7 forming a supporting surface.

The centers of the spherical surface bearings 16 are, seen axially, at the same location as the centers of the bearings 4 of the roller 3, i.e. they lie in the same vertical plane 5 and 6, which is perpendicular to the axis W of the roller 3 and the axis R of the doctor tube 13.

A hose 40 is attached to the carrier 14 on the side facing the roller 3 and extends in the axial direction over the working width of the roller 3, i.e. extends over the width of the web 10 and is compressed and closed at the ends between the inner circumference 15 of the doctor tube 13 shaped pieces 41, 42 which are connected to one another by radial screws 43. The hose 40 can be filled with a fluid pressure medium, in particular hydraulic fluid, via a feed line 44.

On the opposite side there is a corresponding the hose 50 is arranged, which can be filled with the fluid pressure medium via a feed line 54. The tubes 40, 50 each have a starting angle of approximately 90 °. The resulting force acting against the roller 3 results from the pressure difference in the hoses 40, 50.

In the area of the working width of the coating device 100, the doctor tube 13 has the cross-sectional shape shown in FIGS. 3 and 4. The doctor tube 13 has a relatively large wall thickness and is on the side facing the roller 3 by mutually opposite sides of the connecting plane E of the axes of the roller 3 and the rakei tube 13 perpendicular to this in the same plane milled 37,38 flattened so that a web 39 remains between them, which extends parallel to the plane E and forms the doctor blade 60 with the doctor edge 45. The cutouts 37, 38 with the web 39 are formed symmetrically on the two opposite sides of the doctor tube 13, so that the doctor tube 13 can be rotated through 180 ° and operated in both positions.

Since the bearings of the squeegee tube 13 and the roller 3 lie in the same planes 5 and 6, the course of the squeegee edge 45 can be adjusted by correspondingly pressurizing the hoses 40, 50 so that they follow the course of the opposite surface line Roller 3 adapts optimally. If the pressure changes, the adjustment is retained. As a result, a particularly uniform coating thickness can be produced on the web 10 that passes between the roller 3 and the doctor edge 45.

5, a modified coating device 200 is shown more schematically, in which a roller 3 interacts with a non-rotatable doctor tube 113, in which the support device working with a fluid pressure medium is formed by a longitudinal chamber 140 shaped like a cylindrical cylinder. The longitudinal chamber 140 is formed on both sides of the active plane, ie on both sides Part of the plane E connecting the axes of the doctor tube 113 and the roller 3, longitudinal seals 104, 105 attached to the carrier 114 and end transverse seals 106, 107 attached to the ends of the working area of the doctor tube 113. The seals bear against the inner circumference 115 of the doctor tube 113. The longitudinal chamber 140 is located on the side of the squeegee gap 102 and forms a pressure chamber which supports the inner circumference 115 of the squeegee tube 113 upwards with force that is uniform over the working area per unit length. This should be indicated by the hatched representation. The fluid pressure medium is fed via a line 144 in the form of a longitudinal bore of the carrier 114 and a connection bore at the right end of the longitudinal chamber 140 in FIG. 5 and discharged again through the line 154 at the left end of the longitudinal chamber 140 in FIG. 5. A desired pressure can be maintained in the longitudinal chamber 140 by throttling a valve 155 arranged in the line 154. Pressure medium passing from the longitudinal seals 104, 105 into the opposite longitudinal chamber 150 is likewise removed in a suitable manner by a line (not shown). A counter-pressure can be maintained in the longitudinal chamber 150 by appropriate throttling, so that the pressure acting on the doctor blade 160 is based on the pressure difference.

It may be necessary to heat the doctor blade 160, generally to heat it. This can be done in such a way that the fluid pressure medium, usually hydraulic oil, acting in the longitudinal chamber 140 is removed from a storage container 120 by means of a pump 121 and passed through a heat exchanger 122 before it enters the roller via line 144 . The temperature-controlled, usually heated pressure medium is removed again at the other end of the roller via line 154 and thus circulated, the pressure being maintained by valve 155. The heat of the temperature-controlled pressure medium is applied to the inner circumference 115 of the doctor tube 113 and in this way the doctor blade 160 transferred.

FIG. 7 shows a coating device 300 which has been modified again with regard to the support device and which partially corresponds to the coating device 200 and of which only the doctor tube 113 is shown. Instead of a longitudinal chamber 140 extending across the width of the working area, as in the coating device 200, in FIG. 7 there are many piston-like support elements 240 arranged closely behind one another on the side facing the roller 3 in radial cylindrical recesses 241 in the exemplary embodiment, bores of the crosshead 114 out, which rest with their top 242 against the inner circumference 115 of the doctor tube 113. In the exemplary embodiment, twenty-three such support elements 140 are shown, but the number can also be larger or smaller. The support elements 240 can be supplied with hydraulic pressure medium individually, in groups or together via a supply arrangement 243 running in the crosshead 114. The lead arrangement 243 is only shown schematically by a single dashed line. If the support elements 240 are not supplied with hydraulic fluid together, the supply line arrangement consists of a number of individual lines corresponding to the number of groups or the support elements 240. By appropriately loading the individual support elements 240, a desired support profile can be set, which does not necessarily include a constant support force per unit length over the length, as is the case with the longitudinal chamber 140 of FIG. 5.

A particular advantage of the coating device 300 with the support elements 240 lined up lies in the possibility of adapting the support area in the width direction of the web to its width, in that support elements 240 located outside the web width can be switched off. This is symbolized in FIG. 7 by the fact that the four supporting elements located outside the width of the web each have connecting lines which do not extend as far as the line Arrange array 243 as shown at 240 '.

The support elements 240 are closed cylindrical pistons which are supported on the pressure cushion which is formed by the pressure medium present in the cylinder chamber 244 formed in the recess 241. The crosshead 114 bends slightly below the line load of the support elements 240 as shown in FIG. 7. As a result, the cylindrical recesses 241 deform somewhat. Some play must therefore be left or working on the support elements 240 with piston rings or other seals. These seals will not be hermetically sealed, so that some leakage liquid escapes from the support elements 240, which accumulates in the support element area which is sealed axially outward by the end cross seals 245 and is discharged via lines, not shown.

To temper the doctor blade 160, the temperature control medium 300 can also be supplied to the intermediate space between the inner periphery 115 of the doctor tube 113 and the carrier 114 via a line 144 in a heat exchanger 122, as is shown in FIGS Dashing is indicated. In this case, however, the pressure of the heat transfer medium only needs to be sufficient for circulation, since in this case the force against the inner circumference 115 of the doctor tube 113 is applied by the support elements 240.

FIG. 9 shows a modified coating device 400 which is based on the principle of the pressure pad of the coating device 100. The pressure pad 40 facing the roller 3 sets the squeegee 160 against the roller 3. In operation, when the roller 3 rotates in the direction of the arrow, a linear force K is produced on the doctor blade 160 perpendicular to the plane Ξ, which the doctor tube 113 seeks to take along parallel to the web and which is capable of bending without any special measures .

In order to counteract this effect, the direction of the force K is applied to the spreading device 400 - 11 - opposite side of the carrier 114, an additional pressure pad 70 is provided, which acts perpendicular to the plane E and stabilizes the doctor tube 113 against the force K and keeps it straight.

As can be seen from FIG. 6, the doctor tube 113 is also relatively thick-walled. On its circumference there are plane millings 138 that are approximately parallel to the center and have axially parallel plane millings 138, the boundary surfaces of which are approximately perpendicular to the millings 138 and form the actual doctor blades 160.

In practice, roller 3 and doctor tube 13, 113 are designed such that the product of surface moment of inertia and modulus of elasticity is constant at each point of roller 3 and doctor tube 13, 113 along their axes and is the same for roller 3 and doctor tube 13, 113 . As a result, the gap height h on the doctor blade 160 can be maintained uniformly over the working width even when the line force acting on the doctor tube 13, 113 in the roll gap changes, by adjusting the pressure in the support device.

This in turn gives the possibility of being able to regulate the line thickness or the thickness of the coating by taking a measurement of the application thickness on the coated web and regulating the pressure in the support device accordingly. Because of the constancy of the product of the area moment of inertia and the modulus of elasticity, the gap height and thus the application thickness remains constant even with the pressure fluctuations caused by the control over the width of the material web.

Claims

Patent claims 1. Coating device (100, 200) with a rotating roller (3), around which a web (10) provided on the outside with an application of a coating agent can be guided in a wrapping area, with a doctor blade (60, 160) parallel to the roller (3), which can be adjusted from the outside in the wrapping area against the web (10) or the roller circumference, characterized by the following features: a) the doctor blade (60, 160) is on the outer circumference of a non-rotatable doctor tube (13, 113) extending over the length of the roller (3) ) arranged; b) the length of the doctor tube (13, 113) is penetrated by a non-rotatable carrier (14, 114) leaving a circumferential spacing against the inner circumference (15, 115) of the doctor tube (13, 113), against which the doctor tube (13, 113) passes over a carrier (14, 114) ) attached support device (40, 140, 240) which acts against the inner circumference of the doctor tube (13, 113) and works with a fluid pressure medium; c) the outer supports (16) at the ends of the doctor tube (13, 113) lie in the same planes (5, 6) perpendicular to the axis (W) of the roller (3) as the centers of the bearings (4) of the roller (3 ). 2. Coating device according to claim 1, characterized in that in the intermediate space (24) two supporting devices (40, 50; 140, 150) working with a fluid pressure medium are arranged diametrically opposite one another in the effective plane (E). 3. Coating device according to claim 1 or 2, characterized in that the support device located on the side of the squeegee (60, 160) is assigned an additional support device (70) offset by 90 ° in the circumferential direction, which counteracts the squeegee tube (13, 113) forces exerted by the web (10) perpendicular to the active plane (E) on the squeegee (60, 160). 4. Coating device according to one of claims 1 to 3, characterized in that a tempering device (122) is provided, by means of which the fluid pressure medium can be tempered. 5. Coating device according to one of claims 1 to 4, characterized in that a tempering device (132) is provided, by means of which a separate fluid heat transfer medium can be tempered, which can be passed through the interior of the doctor tube (13, 113). 6. Coating device according to one of claims 1 to 5, characterized in that the support device is arranged in the space between the carrier (14) and doctor blade tube (13) on the side facing the roller (3), except for a supply opening (46) closed , Cushion (40) which is inflatable through the fluid pressure medium and extends essentially over the length of the working area of the coating device (100). 7. Coating device according to one of claims 1 to 5, characterized in that the support device one in the intermediate space (24) between the carrier (114) and Doctor tube (113) on the side facing the roller (3) through two opposite to each other with respect to the effective plane of the doctor tube (113), essentially over the working width of the doctor tube (113), against the inner circumference (115) of the doctor tube (113) adjacent longitudinal seals (104, 105) and end transverse seals (106, 107) comprise divided, approximately part-cylindrical shell-shaped longitudinal chamber (140) which can be filled with a fluid pressure medium. 8. Coating device according to one of claims 1 to 5, characterized in that the support device in cylinder-like recesses (241) of the carrier (114) comprises ge piston-like support elements (240) which means in the cylinder chambers (244) under the support elements ( 240) introducible fluid pressure medium can be pressed against the inner circumference (15, 115) of the carrier tube (13, 113). 9. Coating device according to claim 8, characterized in that numerous support elements (240) are provided in a row and at the ends of the row a selectable number of support elements (240) can be switched off to the flui¬ the pressure medium. 10. Coating device according to one of claims 6 to 9, characterized in that the feed lines (44, 54) or (144, 154) or (243) to the cushions (40, 50) or the longitudinal chambers (140, 150) or cylinder chambers (250) are formed by longitudinal and transverse bores of the carrier (14, 114). 11. Coating device according to one of claims 1 to 10, characterized in that both in the roller (3) and in the doctor tube (13,113) including any pin (3 '), the product of the area of inertia and modulus of elasticity over the entire Length is constant and is the same in both. 12. Coating device according to one of claims 1 to 11, characterized in that the supports (12) of the doctor tube (13) under the pressure of a fluid Druckme¬ medium against the bearings (7) of the roller (3) can be pressed. 13. Coating device according to one of claims 1 to 12, characterized in that between each support (12) of the bearing tube (13) and the respective bearing (7) a wedge adjustment (30,32) of the distance and thus the gap height (h ) is provided on the squeegee edge. 14. Coating device according to one of claims 1 to 12, characterized in that the gap height (h) via a continuous thickness measurement of the coating applied to the web (10) is adjustable. 15. Coating device according to one of claims 1 to 14, characterized in that the doctor blade (60, 160) is integrally connected to the doctor tube (13, 113). 16. Coating device according to claim 15, characterized in that the doctor blade (60, 160) is machined out of the cross section of the doctor tube (13, 113). 17. Coating device according to claim 16, characterized in that the squeegee (60) by attaching ebe¬ ner, parallel to the axis (R) of the squeegee tube (13), from opposite sides to approximately the center, but one to The circumference of the squeegee tube is formed by the web (39) as a squeegee (60) leaving cutouts (36, 37) of the circumference of the squeegee tube (13). 18. Coating device according to claim 16, characterized in that the doctor blade (160) by attaching a flat, to the axis (R) of the doctor tube (13) parallel one side up to approximately the middle of the cutout (138) of the circumference of the doctor tube (113) is formed.