EP2105211B1 - Method for coating a blade - Google Patents

Abstract

The method comprises spirally winding a blade body (30) to be coated on a cylindrical base with a blade top side (32) and a blade lower side (34), coating the blade sides with a coating material, hardening the coating material through the coating (15), and unwinding the coated blade (10) from the cylindrical base. The coating is applied under a gradient, which corresponds to the gradient of the blade body. The procedure is repeated for coating of the other blade side. The blade side is subjected to a pretreatment such as sandblasting, grinding or brushing before the coating process. The method comprises spirally winding a blade body (30) to be coated on a cylindrical base with a blade top side (32) and a blade lower side (34), coating the blade sides with a coating material, hardening the coating material through the coating (15), and unwinding the coated blade (10) from the cylindrical base. The coating is applied under a gradient, which corresponds to the gradient of the blade body. The procedure is repeated under coating of the other blade side. The blade side is subjected to a pretreatment such as sandblasting, grinding or brushing before the coating process. The coating is carried out under rotating the cylindrical base and axial displacement of the application of the coating material or the cylindrical base. A binder coating is applied on the blade side before the coating process. The hardened coating is subjected to a thermal and/or mechanical treatment such as milling, grinding or polishing. Independent claims are included for: (1) a blade; and (2) a device for coating the blade.

Description

The invention relates to a method for coating a blade.

Blades are used today for a variety of uses. For example, it is known to use blades in paper machines. Here, the blade is placed and contacted immediately adjacent to a moving surface, in particular a rotating roller or drum, for example, to remove water from the surface of a roller, to set a coating thickness, to remove an excess of coating To keep the surface of a roll of foreign matter or to detach a layer or a fabric or the like from a roll or drum. In papermaking, such blades are used in the form of doctor blades, doctor blades or scrapers at various locations, e.g. in the forming, pressing or drying section as well as in calenders.

There are a variety of different types of blades with different dimensions and made of different materials available on the market EP 1 123 751 A1 Composite blades and a method for their production. document US 2007/0042205 A shows the features of the preamble of claim 1.

It is understood that high demands are made on blades, as insufficient removal of foreign matter / sheet material / water or the like brings fatal effects, leads to disruptions in the operation and generally has particularly adverse effects on the quality of the product to be produced.

Since the blades are in direct contact with a moving surface, such as a roller surface, in a paper machine, for example, the blades are subject to high wear over time. Depending on the purpose, the durability or life of a blade can be a few hours to several months.

In order to be able to modify the properties of the blade material in a targeted manner, for example in order to increase the strength of the blade or the wear resistance for a longer service life and thus increase the service life, a coating of the blade material is expedient. Known coating methods, for example, lead a strip-shaped body linearly past an application nozzle with which a corresponding coating material is applied. Disadvantage of such known methods, however, is in particular the irregular thickness of the applied coating. This leads to various problems when using a blade coated in this way: for example, the blade which is in direct contact with the roll surface can no longer guarantee a uniform cleaning of a surface, the service life is shortened, since the fluctuating coating thickness has a disadvantageous effect on the properties of the blade material. One. Quality loss of the product produced is also to be feared. Also, an uneven coating can adversely affect the blade holder, which may not ensure a secure grip. A possible spalling of the coating is thereby more likely.

The present invention is therefore based on the object of specifying a method for coating a blade, which reduces the disadvantages described, with a uniform coating to be obtained in a simple manner without high effort in a rational manner.

The object of the invention is achieved by a method for coating a blade according to claim 1, wherein the blade has a blade body with a blade top and a blade bottom, with the steps of the spiral Winding the blade body to be coated on a cylindrical base body with the blade side to be coated to the outside, coating a blade side of the wound blade body with a coating material, after curing of the coating material performing a cut through the coating, which is placed under a slope which the slope of the on the cylindrical base body spirally wound blade body corresponds, and unwinding of the coated blade of the cylindrical base body.

The blade body is wound spirally on a cylindrical base body for carrying out the method according to the invention. For this purpose, it is expedient if the blade body has a suitable elasticity or flexibility in order to be wound up accordingly. The cylindrical base body is, for example, a roller or drum rotatable about its center axis, onto the shell of which the blade body is wound in such a way that the wound-up blade body comes to lie so that its surface can be coated on one side. The thus wound up blade body can be suitably fastened to the cylinder at the respective ends by fixing or holding means, as known from the prior art. The blade body may be either a single blade or a blade body from which several individual blades are cut after coating.

The cylindrically wound blade body is then coated accordingly. For this purpose, a casting, Rotationsgieß- or extrusion process is preferably used. Here, the coating material is applied to the outside of the surface to be coated, while the surface to be coated rotates. The coating can be applied in one or more layers. Unlike the conventional rotary molding or rotational molding according to the invention, not the inner surface of a rotating molding coated, but the outside of a quasi wound as a molding blade body, which rotates during the coating together with the cylindrical body.

The coating can also be carried out using an extruder. The coating according to the invention with rotation of the cylindrical body and axial displacement of the application nozzle of the coating material or performed the cylindrical body. The speed of rotation of the cylindrical body as well as the feed rate are coordinated so that a coating thickness of the desired thickness is continuously generated over the area to be coated.

The material of the coating according to the invention is not particularly limited, any coating material can be used. For example, existing blade properties may be varied or modified by the coating. The coating material may for example be selected from one or more polymers. According to the invention, it is also possible to use prepolymers which are subsequently processed further into the polymer. By "prepolymer" is meant mostly oligomeric, but in some cases even already polymeric compounds which serve as a precursor or intermediate for the synthesis of high molecular weight compounds.

Preferred polymers are so-called reaction polymers or resins. Reaction polymers or resins are used for example in the form of prepolymers, which cure without the elimination of volatile components by polymerization or polyaddition to give anomer. Examples of reaction polymers are epoxy resins, phenolic resins such as phenol-formaldehyde resins (novolaks and resoles), melamine-formaldehyde resins, and saturated and unsaturated polyester resins.

Further suitable coating materials are preferably rubbers, polyurethanes, polyureas, thermoplastics or mixtures thereof. Exemplary thermoplastics are acrylonitrile butadiene styrene, polyamide, polycarbonate, polyethylene, polypropylene, polystyrene, polyvinyl chloride, and the like.

The coating material may, if necessary, be admixed with functional fillers in order to modify the properties of the coating accordingly. These properties may be, for example, greater or lesser hardness, greater or lesser strength, increase or decrease in lubricity, or the like.

According to a further preferred embodiment of the invention, the coating material may also contain suitable fibers, in particular reinforcing fibers. The reinforcing fibers in the coating according to the invention may have an orientation or be distributed randomly.

After complete curing, for example vulcanization, of the coating material, an after-treatment of the coating obtained may optionally be carried out. This may be a thermal and / or mechanical aftertreatment. For example, a heat treatment of the coating can be carried out. Machining may also be performed, such as grinding or polishing the coating or treatment using suitable tools such as knives, disc cutters or the like.

In the method according to the invention, after curing of the coating material, part of the coating obtained is removed. For this purpose, a cut is made through the applied coating, which is placed under a pitch that corresponds to the pitch of the wound on the cylindrical body blade body. This makes it possible to obtain a uniform coating, which according to the invention is preferably in the range of 0.1 mm to 2 mm. Particularly preferably, a thickness of the coating measured perpendicular to the direction of extension of the blade deviates by less than 5%, preferably by less than 1%, from the average layer thickness over the extent of the coating.

Following this, the finished coated blade body can be unwound. It goes without saying that the method according to the invention can also be used to coat the other not yet coated blade side by repeating the steps described above.

Optionally, the blade side of the blade body to be coated may be pretreated prior to coating. As a pretreatment, any method can preferably be used for roughening the blade side to be coated, which can serve, for example, to improve the adhesion of the coating. Suitable pretreatments are sandblasting, grinding or brushing the surface to be coated. Furthermore, for example, an adhesive coating can be applied before coating.

The coated blade body obtained according to the invention can be used as a single blade; It can also be cut through cuts several blades of endless material.

Figur 1

in schematisiert vereinfachter Darstellung beispielhaft eine erfindungs- gemäß hergestellte Ausführungsform einer Klinge mit einer aufgebrachten Be- schichtung;

Figur 2

in schematisiert vereinfachter Darstellung beispielhaft eine erfindungs- gemäß hergestellte Ausführungsform einer beschichteten Klinge eingesetzt in ei- nen Klingenhalter; und

Figur 3

in schematisiert vereinfachter Darstellung beispielhaft eine Vorrichtung zur Durchführung des er- findungsgemäßen Verfahrens.

Hereinafter, the present invention will be explained with reference to figures, which illustrate the teaching of the invention, but are not intended to be limiting. Show here

FIG. 1

a schematic simplified representation of an example produced according to an embodiment of a blade with an applied coating;

FIG. 2

a schematic simplified representation of an example produced according to an embodiment of a coated blade used in a blade holder; and

FIG. 3

in schematic simplified representation of an example of an apparatus for carrying out the inventive method.

FIG. 1 shows in a simplified schematic representation of an exemplary embodiment of a coated blade 10. The blade has a blade tip or edge 12 which is chamfered, for example, to find use as a doctor blade 20 use. The blade 10 has opposite to the blade tip or edge 12 a rear portion 14 which can be inserted into a corresponding holder (not shown). The blade body 30, in particular the blade upper side 32 of the blade body 30, is in the example shown provided with a coating 15 over its entire surface. The coating material is not particularly limited and may be selected, for example, from one or more of the group consisting of epoxy resins, melamine-formaldehyde resins, saturated and unsaturated polyester resins, rubber, polyurethanes, polyureas, epoxy resins, phenolic resins such as phenol-formaldehyde resins, thermoplastics such as acrylonitrile-butadiene-styrene , Polyamide, polycarbonate, polyethylene, polypropylene, polystyrene, polyvinyl chloride, or mixtures thereof, optionally with the addition of functional fillers and / or corresponding reinforcing fibers.

Some classes of preferred polymers are briefly explained below, without the coating material being restricted thereto:

Polyurethanes are plastics or synthetic resins, which arise from the polyaddition reaction of diols or polyols with polyisocyanates. Suitable isocyanate components are, for example, diphenylmethane diisocyanate (MDI), polymeric diphenylmethane diisocyanate (PMDI), toluene diisocyanate (TDI), naphthylene diisocyanate (NDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) and the like. Exemplary polyols are polyester polyols or polyether polyols.

Polyureas are elastomers prepared by polyaddition of diisocyanates and diamines.

Epoxy resins consist of polymers which, depending on the reaction conditions, with the addition of suitable hardeners, give a thermosetting plastic of great strength and chemical resistance.

Phenolic resins result from the synthesis of phenols with aldehydes.

Rubber is understood according to the invention vulcanized rubber, in particular synthetic rubber, for example prepared based on styrene, butadiene, acrylate, and / or vinyl acetate.

The material from which the blade 10 is constructed, is also not limited, as long as it can be wound on a rotatable cylindrical base body for coating according to the inventive method. Thus, any metal, metal alloy, plastic or fiber reinforced plastic can be used as long as the blade material is sufficiently suitable for the intended purpose. The blade 10 can be executed in one or more layers.

In the example shown, the applied coating 15 has a thickness in the mm range, in particular between 0.1 and 5 mm.

The blade body 30 may be coated on the blade top 32 and / or the blade bottom 34 of the blade 10; preferably only one side is coated. If both sides of the blade 10 are coated, the coatings may be selected from the same or different coating material and may be the same or different thicknesses on the blade upper and lower sides 32, 34.

FIG. 2 Illustrates in simplified manner an example of a coated blade 10, for example a doctor blade 20, which is inserted into a blade holder 100. For example, in addition to a scraper, the blade 10 can also be used in a coater or other device. In the example shown in FIG. 2 For example, the surface of a roller 50 rotating in the direction of the arrow A is scraped with the blade 10 inserted into the blade holder 100 belonging to the blade 10. The applied to the blade 10 coating 15 is located flat on the entire blade top 32 of the blade body 30. In the example shown is only a surface of the blade body 30, that is, the blade top 32 of the blade body 30, coated. Of course, the blade bottom 34 may be coated. The applied coating 15 is applied in such a way that the most uniform possible thickness is obtained in order to avoid the disadvantageous effects resulting from non-uniform layer thicknesses. By applying a corresponding coating 15, the properties of the blade 10 can be modified accordingly and adjusted in the desired manner.

FIG. 3 illustrates in simplified manner an exemplary embodiment of a device 200 for coating a blade 10 while carrying out the method according to the invention.

First, a blade 10 to be coated of suitable dimensions, from which either a single blade can be obtained or later several individual blades can be cut, is used. The blade material can be arbitrary provided that it meets the required requirements for the intended use. Before the actual coating, it may be advantageous to subject the surface of the blade 10 to be coated, in particular the blade top side 32 and / or blade bottom side 34 of the blade body 30, to a corresponding pretreatment. For example, the surface to be coated can be roughened by suitable measures, such as sandblasting, grinding, brushing or the like. It can also be applied an adhesive coat.

To apply the coating material, the blade 10 to be coated is wound onto a cylindrical base body 60, for example onto a roller or drum. This takes place spirally, ie the respective side of the blade 32 or 34 to be coated is offset with the side 32 or 34 to be coated to the outside, so that the entire surface can be coated. The thus wound blade body 30 is then coated on the outward side of the roller 60 side 32 or 34, for example, using a casting or Rotationsgieß- or extrusion device 110. During coating, the roller 60 rotates in the direction of arrow B about its central axis. The coating is carried out with rotation of the roller 60 and with simultaneous axial displacement of an applicator device 120 for the coating material, such as a nozzle, or at the same time axial Moving the cylindrical body 60 in the direction of the arrow R of FIG. 3 , preferably continuous, applied.

The polymeric coating material may be selected according to the desired coating 15. In the example of FIG. 3 polyurethane is used as a coating material. The coating material consists in the example of component 1 and component 2. As component 1, a polyurethane prepolymer is used here. In this case, a reaction product is preferably used, which is preferably first vacuum degassed and is composed of a polyol and a diisocyanate. The processing temperature for component 1 is 50 to 150 ° C. As component 2, for example, a hardener mixture can be used, which may be composed of 1-99% polyols or polyol mixtures, 1-99% diamines or diamine mixtures and 0-1% catalyst. The processing temperature of component 2 is 50-150 ° C. The mixing ratio of component 1 and component 2 is in the example chosen corresponding to 80-120% of the stoichiometry.

The processing of the component 1 and component 2 in the casting device 110 takes place, for example, flow-controlled. It can be used an additional mixing device, which is arbitrary selectable. The device and process parameters are selectable depending on the coating material, desired coating thickness, blade material, intended use of the blade, and the like. By way of example, the parameters are listed as follows: caster: flow controlled 2k medium pressure casting machine Mixing head: Dynamic mixing chamber according to the rotor-stator principle Total emissions: 100 to 10,000 g / min, Peripheral speed: 15-80 m / min, feed: 5-100 mm / rev, Application thickness: 0.1-2 mm

The parameters can be adjusted by a person skilled in the art by a few orienting experiments based on his knowledge, based on the above explanations.

After complete curing of the coating 15, an after-treatment of the coating 15 can optionally be carried out. This may be a thermal and / or mechanical aftertreatment of the coating 15, such as grinding, milling and / or polishing. After the optional post-treatment, cutting is performed using a suitable cutting device 130. The cutting device 130 in the form of a suitable cutting tool may, for example, represent a knife, a jet cutting device such as a water jet or the like. The cutting device 130 for performing the cut is in this case preferably arranged and controllable relative to the cylindrical base body 60 such that the cut can be placed under a pitch which corresponds to the pitch of the spirally wound blade body 30.

This makes it possible according to the invention to provide a blade 10 with a coating 15 which shows a uniform thickness over the entire coated blade surface, so that a thickness of the coating 15 measured perpendicular to the direction of extension of the blade 10 by the extent of the coating 15 by less than 5%. , preferably by less than 1%, deviates from an average layer thickness.

The FIGS. 1 to 3 illustrate only exemplary embodiments possible. These are not meant to be limiting, but merely represent examples of possible embodiments FIGS. 1 to 3 are not exhaustive and thus not restrictive with regard to the scope of protection according to the invention. Other dimensions and shapes and other than the described polymers for coatings are conceivable depending on the desired property profile.

LIST OF REFERENCE NUMBERS

10

blade

12

Blade tip or beveled blade edge

14

rear area of the blade

15

coating

20

scraper

30

blade body

32

Blades top

34

Blade bottom

50

roller

60

cylindrical body

100

blade holder

110

Casting or extrusion device

120

applicator

130

cutter

200

Coating device according to the invention

A

Direction of rotation of the roller 50

B

Direction of rotation of the cylindrical body 60th

R

feed direction

Claims (10)

1. Method for coating a blade (10), the blade (10) having a blade body (30) with a blade upper side (32) and a blade lower side (34),
   characterized by the following steps:

   - spirally winding the blade body (30) to be coated onto a cylindrical base (60) with the blade side (32, 34) to be coated on the outside,

   - coating one blade side (32, 34) of the blade body (30) that has been wound on with a coating material,

   - following the hardening of the coating material, making a cut through the coating (15), which is set with a slope which corresponds to the slope of the blade body (30) wound spirally on the cylindrical base (60), and

   - unwinding the coated blade (10) from the cylindrical base (60).
2. Method according to Claim 1,
   characterized in that
   the method according to Claim 1 is repeated, coating the other blade side (32, 34).
3. Method according to Claim 1 or 2,
   characterized in that
   the coating is carried out while rotating the cylindrical base (60) and axially displacing the application of the coating material or the cylindrical base (60).
4. Method according to one of Claims 1 to 3,
   characterized in that
   the blade side (32, 34) to be coated is subjected to a pre-treatment before the coating.
5. Method according to Claim 4,
   characterized in that
   the pre-treatment used is a method for roughening the blade side (32, 34) to be coated.
6. Method according to Claim 5,
   characterized in that
   the roughening method is chosen from sandblasting, grinding or brushing the blade side (32, 34) to be coated.
7. Method according to Claim 6,
   characterized in that
   before the coating, an adhesive primer is applied to the blade side (32, 34) to be coated.
8. Method according to one of the preceding claims,
   characterized in that
   the coating (15) is subjected to a post-treatment following the hardening.
9. Method according to Claim 8,
   characterized in that
   the post-treatment used is a thermal and/or mechanical post-treatment.
10. Method according to Claim 9,
    characterized in that
    the mechanical post-treatment is chosen from milling, grinding or polishing.

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