FI87942B - Reinforced covering for a roll in a paper-making machine, and procedure for producing the same - Google Patents

Description

87942

Reinforced coating of a roll of a paper machine and method of making the same For the rolls of paper rolls and the mask and the front of the paper machine

The invention relates to a roll of a paper machine, in particular a central or calender roll, comprising a roll body and a reinforced coating thereon, which is surrounded by an adhesive layer and a surrounding cover layer.

The invention also relates to a method for producing a roll of a paper machine, in particular a central or calender roll, which roll comprises a roll body and a reinforced coating thereon, in which method a cast iron or steel jacket is ground to shape, after which the roll is preferably sandblasted.

The roll according to the invention can be, for example, the central roll of a press or a fish-roll, with which the web is in direct contact and from which the web is detached.

Coated rolls are used in paper machines and paper finishing machines in a wide variety of applications. Applications include press rolls, suction rollers, soft rolls for calendars and supercalenders, and the like. The roll coating is subject to different quality requirements in different applications and in different processes. Conventional coating quality factors include e.g. hardness at a given temperature, 30 temperature resistance, compression resistance, chemical resistance,:. surface smoothness, resistance to mechanical damage, elasticity, .surface energy, paper release properties, electrical conductivity and non-aging.

,. 35 It is known that the press section of a paper machine uses a design made of granite. The popularity of granite is based on its surface properties, which cause the controlled paper web to detach from the surface of the stone. In addition, granite withstands the abrasive effect of a scraper well. However, granite 2 87942 accounts have some disadvantages which have led to the development of synthetic rolls and thus lighter structures.

In the past, attempts have been made to reinforce roll coatings in various ways to make them more durable.

Rolls of paper machines and other similar rolls can be coated with e.g. elastomeric materials, e.g. by molding, spraying or twisting the strip onto the roll body. Applicant's previous application F1 10 850806 discloses, for example, an elastomeric coating reinforced with long filled yarns or the like which retains the prestress during use of the roll. When used as a press of a paper machine press, a very high prestress is required for the reinforcement of such a coating tape.

15

The need to improve the mechanical properties of the coating materials while saving the weight of the roll are thus factors which have greatly influenced the development of the reinforced materials.

20 It is known that some fibrous materials have a strength ten times higher than that of the corresponding solid and, because they exist as very fine monocrystals, they can achieve almost theoretical durability.

25 By combining suitable fibers and matrix materials, properties that would not be possible with conventional materials have been achieved. Equipment for the production of such fiber-reinforced composites exists, such as thermostatic pressing equipment, which, however, is only suitable for the production of small parts.

It is an object of the present invention to provide a roll in which a reinforced roll coating is partially provided by utilizing the above novel fiber reinforcement technique.

35 3 87942

The present invention relates to a roll which better meets the requirements set for the middle * or fish blade rolls of a paper machine in terms of the strength and peeling properties of the coating.

To achieve this, the roll according to the invention is mainly characterized in that the adhesive layer and the inner part of the thermally sprayed cover layer contain a continuous fiber reinforcement wound around the roll.

The method of manufacturing a paper machine roll according to the invention is mainly characterized in that an adhesive layer material is sprayed on the jacket surface and a continuous fiber is wound around the roll between injections, and thus continued until the adhesive layer reaches its final thickness. the outermost layer is sprayed using only the cover layer material 20 - after which the surface of the roll is finished in a manner known per se.

Preferred embodiments of the invention have the features of the subclaims.

The coating of the roll according to the invention is produced in a new way and the roll bodies are known from a prior art, e.g. by casting or by bending and welding from a sheet. Sandblasting is performed to achieve proper infection. In sandblasting, the surface of the roll is roughened (and cleaned) so that sand grains are shot into the surface with the help of compressed air, which forms the surface and removes the substance from it. Sandblasting uses a grain size of 16-120 mesh depending on the desired roughness.

The present invention thus provides a method in which continuous fibers are used in the coating of a roll and matrices of composite materials can be produced by thermal spraying.

4,87942

In general, there are two factors that limit the use of thermally sprayed roll coatings, i.e., the tensile stresses generated in the coating and the detachment of the interfaces as a result of fatigue and / or corrosion. These disadvantages can be minimized by using reinforcements inside the coatings according to the invention, which bias the coatings to the compressive stress side and, when the interfaces are detached, prevent large pieces of coating from coming off the surface. The coating according to the invention is thought to be applied mainly to the middle and calender rolls of a paper machine.

10

In the invention, the roll coating is manufactured, for example, by grinding a cast iron or steel casing into its shape and sandblasting the roll, after which the adhesive layer material is started to be sprayed onto the surface of the casing. Preferably, after a few overspans (in which case the thickness is about 20-40 μm), a continuous fiber is wound around the roll between injections. The adhesive layer is sprayed to its final thickness of 0.05-1.5 mm, preferably 0.8 mm by winding the fiber between spraying sweeps. The cover layer material is then sprayed 0.1-0.5 mm, preferably 0.2 mm by winding the fiber between the sprayings 20. The outermost layer, which is about 0.05-5 mm, preferably 0.5 mm, is sprayed using only the surface layer material.

The adhesive layer material may be e.g. NiCr, where the proportion of Cr is 20-50%, the rest Ni; FeCrNi alloy with 16-35% Cr, 10-32% Ni, the rest Fe; NiCrBSi with 7-28% Cr, 0-4% B, 0-3% Si, the remaining Ni; CoCrSiB with 7-28% Cr, 0-3% B, 0-2.5% Si, the remaining Co; or FeCrSiB with 12-24 * ____ Cr, 0-2.5% B, 0-3% Si, the rest Fe. The latter three are self-melting mixtures. Other compositions suitable for the adhesive bead portion of this invention include: Mo; NiTi with a Ti content of 5-45%; NiAl with 20% aluminum; iron-based superalloys (20-35% Cr, 10-30% Ni, the rest Fe); stainless steel; CrAl with an aluminum content of 40-60%; as well as so-called MeCrAlY alloys, e.g. NiCrAlY (15-30% Cr, 3-12% Al, <1% Y, the rest Ni), FeCrAlY (14-27% Cr, 4-17% Al, <1% Y , remaining Fe), CoCrAlY (10-24 «Cr, 6-14% Al, <1.5% Y, 35 remaining Co), CoNiCrAlY (13-27% Cr, 5-14% Al, z 1.5« Y, the rest Co). The most preferred adhesive layer is selected using two criteria, which are the corrosion conditions of the paper mill and the coefficients of thermal expansion of the top layer and the roll body. The coefficients of thermal expansion are again chosen so that the adhesive layer equalizes the thermal stresses of the substrate and the topcoat.

5

The fiber content of the adhesive layer is 15-50% and the fiber content of the inner part of the cover layer is 8-30%.

The method according to the present invention uses the so-called continuous fiber. 10 By fiber is meant either a circular "yarn" or strips of different height / width ratios. The material of the fibers can be tungsten (with air or ThO 2 alloy), stainless steel, NiCr, glass, carbon, aramid or alumina, as well as the alloys mentioned in Tables 1 and 2 (especially strip).

15

Typical diameters of the applicable fibers are shown in the following Table 1 and for these strength values reference is made to Table 3:20. TABLE 1

FIBER DIAMETER

Tungsten 10-50 μιη 25

Metal fibers> 50 μη »AL2O3 fibers 20 μιη 30 Aramid 20 μιη

Carbon fiber 10 μπι ·: ·. 35

Typical strength values of the applicable fibrous strips are shown in Table 2 below.

6 87942 TABLE 2 5 Composition Strength [N / mm2]

Fe 80 B 20 3500

Fe 90 Zr 10 2200

Fe 80 Z 13 C 7 3100 10 Fe 78 B 10 Si 12 3400

Fe 62 Mo 20 C 18 3900

Fe 62 Cr 12 Mo 8 C 18 3300

Fe 46 Cr 16 Mo 12 C 18 4000 15 Co 90 Zr 10 1900

Co 78 Si 15 B 12 3060

Co 56 Cr 26 C 18 3300

Co 44 Mo 36 C 20 3900

Co 34 Cr 28 Mo 20 C 18 4100 20

Ni 90 Zr 10 1800

Ni 78 Si 10 B 12 2500

Ni 34 Cr 24 Mo 24 C 18 3500 25 Cu 80 Zr 20 1900

From the mixtures mentioned in Table 2, so-called amorphous 30 metals, resulting in excellent strength values. The use of amorphous materials in paper machine conditions has the advantage that they have excellent corrosion resistance.

• For this reason, the production of amorphous coatings by thermal spraying on the surface of paper machine rolls is being studied very strongly.

The strips have widths up to 1 mm and thicknesses from a few tens of micrometers upwards.

40 The use of continuous fiber is cheaper than that of staple fiber (eg SiC,

Al 2 O 3 whiskers) because the continuous fiber not only strengthens the structure but also allows the coating to be prestressed. When staple fibers are used, the structure is only strengthened.

Suitable coating material is any thermally sprayable coating material, such as Al 2 O 3, Cr 2 O 3 ZrO 2, ZrSiO *, WC, self-melting B-Si alloy Fe, Ni or Co mixtures or mixtures of the above.

5 The choice of coating is based on the required surface properties. The roughnesses of ceramic coatings are typically greater than Ra 0.3. Instead, metallic or metal-matrix coatings (self-melting B- and Si-alloyed coatings or W- or Cr-carbides in a Co- or Ni-based matrix) can be polished up to a Ra value of 0.01 μm.

In particular, the calender roll places high demands on the smoothness of the surface, while the center rolls have the advantage of controlled surface roughness control in adjusting the surface energy components of the coating to the coating.

The topcoat almost always has a different coefficient of thermal expansion than the cast iron or steel of the roll shell. The difference in the coefficients of thermal expansion 20 causes stresses at the interface as the roll heats up.

The stresses can be reduced by selecting a coating having a coefficient of thermal expansion between the topcoat and the coefficient of thermal expansion of the roll shell as the adhesive layer.

: 25 After spraying the coating material, the roll is finished, as is known per se, e.g. by sealing with a polymeric material (spraying, ... Painting or electrochemically with metal). Finally, the coating is ground to the desired surface roughness, while at the same time obtaining the correct shape of the roll.

Suitable thermal spraying methods are, for example, plasma spraying, detonation spraying, hypersonic flame spraying, plasma spraying, flame spraying, arc spraying.

35 8 87942

The materials used in thermal spraying can be in the form of either powder or wire.

When using a powdered substance, the size distribution of the powders varies between 5 and 300 μιη. The exact size range depends on the coating method used and the degree of tightness desired. In general, the higher the particle velocity used, the smaller the powder particle size required. The following table shows suitable powder size distributions for the various coating methods used in the invention, with the goal of providing the most dense coating possible.

TABLE 1

15 METHOD PARTICLE SIZE

Detonation spray 5 - 20 μπι

Hypersonic flame spraying 5 - 40 μπι 20

Plasma spraying 10 - 50 μιη

Flame spraying 50 - 120 μιη 25 -

Correspondingly, when aiming for a porous coating, the size distributions should be about 2-2.5 times these values.

: 30

The method of preparation of the powder also affects the final result, since the shape of the particle is determined by the method of preparation. Crushed powders have a faceted shape and agglomerated and atomized powders are round. In addition, the agglomerated powders are porous. When aiming for a dense structure, it is optimal to use round particles because of their good fluidity. From the viewpoint of efficient melting, it is preferable to use porous powders having a specific surface area as large as possible.

40 The wire additive is intended for arc spraying. The diameters of the wires vary between 1-3 mm. The composition may be stainless steel 9 87942, NiCr, iron-based superalloy or aluminum bronze. For each application, the selection is based on the same criteria as for powders.

In the reinforcement of the coating according to the invention, it has been particularly utilized that the strength of the fibers is considerably higher than the strength of the corresponding body when conventionally manufactured. This is because the fibers made by melt quenching have an amorphous or partially amorphous structure that is significantly stronger than that of the crystalline materials. Metallic fibers made by drawing are very strongly shaped and the crystals are strongly oriented. Carbon and aramid fibers also have a strongly oriented structure. Due to the manufacturing methods, the amount of structure-degrading cracks and pores is non-existent.

15

Table 3 below compares the strengths of the fibers and the internal strengths of the coatings.

TABLE 3 20 -

FIBER COATINGS

FIBER STRENGTH COATING STRENGTH

25 [MPa] [MPa] - - Steel 2000-300 Porous oxide 5-20

Tungsten 2000-4500 Dense oxide 40-80; 30

Molybdenum 1000-3000 Dense Tungsten Carbide 100-400: V Glass 2000-5000 ::: 35 ai2o3 1500

Boori 3500

Carbon 2000-3000

Aramides 3000 40 10 37942

It can be seen from Table 3 above that the strength of the fibers is an order of magnitude or orders of magnitude higher, so it is easy to understand that the fibers effectively strengthen the coatings. The price of the fibers increases sharply as the diameter increases, so for another application, 5 fibers as thick as possible must be selected.

In the following, the invention will be described in detail with reference to the accompanying figures, to which, however, the invention is not intended to be narrowly limited.

10

Figure 1 shows an apparatus for wrapping fibers around a roll.

Figure 2 is a schematic view of an apparatus for spraying a matrix coating material around a roll.

15

Figure 3 is a schematic cross-sectional view of a roll according to the invention.

In the invention, a special computer-controlled wrapping unit according to Figure 1 is used for wrapping the fibers, which allows the use of different types of continuous fibers. In Fig. 1, a roll coated with fibers is indicated by reference numeral 1, a control unit by reference numeral 2 and the actuators of the apparatus by reference numeral 3. Fiber 4 is fed around the roll 1 by means of a traversing carriage device 5.

; 25

In addition to the fiber wrapping device, the method ____ of the invention further requires a thermal spray device to spray the matrix material of the reinforced coatings around the roll shown in Figure 2, e.g. JET-KOTE hypersonic flame -30 syringes or plasmatechnik A 3000 plasma syringes. The two-axis unit for the burner tip 7 of the device allows all significant parameters of the system to be controlled and kept within the desired limits, thus allowing a repetitive high-quality injected matrix. In Fig. 2, the roll body is denoted by reference numeral 6 35 and the fibers wound around it by reference numeral 4. The matrix material of the roll body is denoted by reference numeral 8 and the plasma injection head n 87942 by reference numeral 7. The rotation of the roll is also shown. In Fig. 2, the fibers 4 and the matrix material 8 are shown to illustrate the figure separately, although in reality according to the invention the adhesive layer material is first sprayed on the surface of the sheath a few 5 times with the device according to Fig. 2. When the thickness is about 20-40 .mu.m, between the spraying operations, the continuous fiber 4 is wound around the roll 1 by means of the device according to Fig. 1. Thus, the adhesive layer is gradually sprayed to its final strength by winding the fiber 4 between spraying sweeps. The cover material 10 is then sprayed with the device 8 according to Fig. 2 by winding the fiber 4 at desired intervals between injections with the device according to Fig. 1. The outermost layer is sprayed with the device of Figure 2 using only the surface layer material. The fiber was wound at desired intervals.

15

Figure 3 shows a cross-section of a roll 1 according to the invention. It shows the roll body 6, the adhesion layer 9, the cover layer 8 and the fiber reinforcements 4 included in the inner part of the cover layer and in the adhesion layer.

20

With the method according to the invention, only multilayer structures can be made, in which case the fibers are wrapped and the coating material is sprayed in the desired manner, repeating in the desired manner until the desired thickness is reached for each layer.

: 25

With the method according to the invention, the fibers are homogeneously distributed in the matrix in the desired manner. Between individual fibers f. the distances can be between about 50-100 μιη, resulting in a fiber volume of about -20-50%.

30

The method according to the invention can also be used to make ceramic and metallic composite coatings which are reinforced with different fibers and the strength of these materials is several times higher than that of the corresponding coatings traditionally produced.

. ·: ·. 35 12 87942

The following are claims within the scope of which the details may vary within the scope of the inventive idea.

Claims (15)

A paper machine vase, in particular a center or calender roll, comprising a roll body and a reinforced coating on top thereof, around which roll body there is an adhesive layer and a cover layer surrounding it, characterized in that the adhesive layer and the inner portion of the thermal the sprayed coating layer contains continuous fiber reinforcement wound around the roller. 10 2, Vais according to claim 1, characterized in that the thickness of the adhesive layer is within the range 0.05-1.5 mm, advantageously 0.8 mm and the thickness of the inner part of the coating layer containing fiber is within the range 0.1 -0.5 mm, advantageously 0.2 mm and the thickness of the outer part of the coating is within the range 0.05-5 mm, preferably 0.5 mm. Vais according to claim 1 or 2, characterized in that the material in the adhesive layer e.g. may be NiCr, where the halide Cr is 20-50%, the balance Ni; a FeCrNi alloy containing 16-35 20% Cr, 10-32% Ni and the remainder Fe; NiCrBSi, containing 7-28% Cr, 0-4% B, 0-3% Si, the remainder Ni; CoCrSiB, containing 7-28% Cr, 0-3% B, 0-2.5% Si, the rest Co; or FeCRSiB, which contains 12-24% Cr, 0-2.5% B, 0-3% Si, the residue Fe, and Mo; NiTi, where the Ti content is 5-45%; NiAl, where the content of aluminum is 20%; superalloys based on 25 iron (20-35% Cr, 10-30% Ni, the rest Fe); stainless steel; CrAl, where: the content of aluminum is 40-60%; and so-called MCerAlY alloys, e.g. Ni-CrAlY (15-30% Cr, 3-12% Al, <1% Y, residue Ni), FeCrAlY (14-27% Cr, 4-17% AI, <1% Y, residue Fe), CoCrAlY ( 10-24% Cr, 6-14% Al, <1.5% Y, residue Co), CoNiCrAlY (13-27% Cr, 5-14% Al, <1.5% Y, residue Co), the fiber material advantageously consists of stainless steel or tungsten, NiCr, glass, carbon, aramid or alumina, or a mixture of metal and other substance or metal alloy, e.g. FeB, FeZn, FeZrC, FeBSi, FeMoC, FeCrMoC, CoZr, CoSiB, CoCrC, CoMoC, CoCrMoC, NiZr, NiSiB, NiCrMoC, CuZr, the material of the coating layer is Z n 87942 or WC, self-melting B-Si mixtures, Fe, Ni or Co alloys or mixtures of the above. 4. A roller according to any one of claims 1 to 3, characterized in that the continuous fiber is used in the coating. It consists of threads with circular cross-sections or bands of different height / width ratios. Roll according to any one of claims 1-4, characterized in that the following values are suitable for the fiber diameter: W 10-50 µπι, 10 carbon fiber 10 µπι, metal fibers> 50 µπι, Al203 fibers 20 µπι, Aramid 20 µπι and the width pa the fiber band or thread is <1 mm and the thickness is 20-300 μπι. 6. A roll according to any one of claims 1-5, characterized in that the fiber content of the adhesive layer is 15-50% and the fiber content of the inner part of the coating layer is 8-30%. A method of making a roll in a paper machine, especially a center or calender roll, said roll comprising a roll body 20 and a reinforced coating on top thereof, in which method a mold of cast iron or steel is formally welded, after which the roll is advantageously molded. is characterized by starting to spray adhesive layer material onto the surface of the male and: between the sprays, continuous fiber is wound around the roller, and is continued in this manner until the adhesion layer reaches its final thickness,: -: - after this is to coat coating layer material thermally by winding fiber between the sprays, - the outermost layer of the coating layer is sprayed using only coating material. . - after which the roll surface is completed in a manner known per se. Method according to claim 7, characterized in that the spraying method is thermal spraying, e.g. plasma spraying, detonation spraying, hypersonic flame spraying or flame spraying, arc spraying. is 87942 9. A method according to claim 7 or 8, characterized in that the coating materials to be thermally sprayed are in the form of powder or trees. 5 Method according to claim 9, characterized in that the size distribution of the powder varies within the range of 5-20 µm depending on the coating method used and the desired compactness. 11. A method according to claim 10, characterized in that in order to obtain the most compact coating possible, the powder size is in the range of 5-20 µπι, hypersonic flame spray in the range 5-45 µm, in the case of plasma injection in the range 10. -50 µm and in the case of flame spraying in the range 50-120 µm, and to obtain a porous coating, the size distributions of the powder are 2-2.5 fold compared to the above values. Method according to any of claims 7-11, characterized in that in the manufacture of a compact coating, powder with a round particle shape, advantageously agglomerized or finely divided powder is used and in the preparation of a porous coating, powder with an angular particle shape is used, for example. . crushed powder. Process according to any of claims 7-12, characterized in that the materials on the different layers are selected so that their coefficients of thermal expansion equalize the thermal stresses in the substrate and the coating. 14. A method as claimed in claim 7, characterized in that the tree-shaped substance is used for ground spraying and the diameter of the trees is 1-3 mm. 15. A process according to claim 14, characterized in that the composition of the trees is stainless steel, NiCr, superalloys: iron base, aluminum bronze.