JPS63264995A - Press roll for papermaking machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a press roll for a paper making machine.

[Conventional technology]

In the dewatering process, the wet paper produced in the papermaking process is pressed by a press roll while passing over a suction roll to squeeze out the moisture contained therein, and the squeezed out moisture is removed by suction by the suction roll.

The water contained in wet paper is a strongly acidic corrosive liquid called white water, so the press roll that presses the wet paper to squeeze out white water needs to have stable corrosion resistance against white water. It is also necessary to have good paper separation properties against wet paper so that the wet paper that passes while being pressed by the press roll does not adhere to the roll surface and cause problems such as tension.

Conventionally, granite rolls (stone rolls made of granite and cut into a desired shape) have been used as press rolls that have both the above-mentioned paper separation properties and corrosion resistance.

[Problem that the invention seeks to solve]

However, granite is currently difficult to obtain worldwide. Additionally, granite is extremely hard and extremely difficult to process. In addition, the roll has low toughness and is prone to cracking, so it has the disadvantage of poor durability against usage conditions in which bending stress and tarmacing stress are repeatedly applied.

The present invention provides a new press roll for solving the above problems.

[Means and effects for solving the problems] The press roll for a paper making machine of the present invention has a roll body composed of a metal sleeve and a built-up layer covering the outer peripheral surface of the metal sleeve, The layer consists of an austenitic alloy matrix and a 10 to 7 austenitic alloy matrix mixed as a dispersed phase in the matrix.
It is characterized by having a composite structure consisting of 0% by weight of ceramic particles.

FIG. 1 shows a press roll of the invention.

The roll body (10) has a two-layer laminated structure consisting of a metal sleeve (11) and a build-up N (12) formed on its outer peripheral surface, and the roll body (10) has a shaft member ( 20
゜20) is fitted.

Overlay 7 covering the metal sleeve (11)! (12) has a composite structure consisting of a matrix and ceramic particles as a dispersed phase. Hereinafter, this build-up layer (12) will be referred to as a composite build-up layer.

The reason why the matrix metal of the composite overlay layer (12) is an austenitic alloy is to ensure corrosion resistance against white water squeezed out from wet paper, and it is preferably a Ni-based alloy or a CO-based alloy. .

The material of the ceramic particles mixed in the matrix as a dispersed phase is not limited, but from the viewpoint of wear resistance, corrosion resistance, etc.
Carbide ceramics such as silicon carbide (S i C) and chromium carbide (Cr, C,) are preferably used. The particle size may generally be about 0.01-3.5 μm.

The mixing ratio of ceramic particles in the composite overlay layer consisting of a metal matrix and ceramic particles is 15 to 70% by weight. The reason why 15% by weight is set as the lower limit is because if it is less than that, it is not possible to ensure good paper release properties.
Preferably it is 20% by weight or more. On the other hand, the reason why the upper limit is 70% by weight is that if it exceeds 70%, it becomes difficult to form a homogeneous composite overlay, and the paper unraveling property worsens, and the relative amount of matrix metal in the overlay becomes difficult. This is because the reduction in corrosion resistance makes it difficult to ensure the required corrosion resistance. The upper limit is preferably 60% by weight.

The above-mentioned composite overlay layer is made of a mixed powder of metal powder as a matrix and ceramic powder as a dispersed phase, and is used as a weld overlay layer by a weld overlay method such as plasma powder welding, or by a thermal spraying method. It can be formed as a thermal spray overlay layer on the outer peripheral surface of the metal sleeve (11) which is the base material. Since the wet paper does not come into direct contact with the surface of the metal sleeve (11) covered with the composite overlay layer (12), the material can be selected arbitrarily; for example, an inexpensive material such as carbon steel may be used. Can be applied.

Note that the above-mentioned Ni-based alloy serving as the matrix and C
The preferred alloy composition of the o-based alloy and the reasons for limiting the composition are as follows.

ΣKinko C: 0.1% or less, Cr: 10-30%, Mn: 2
% or less, 5il1% or less, Mo: 8 to 18%, the remainder substantially consisting of Ni, or an alloy in which a part of Ni is replaced with W of 6% or less.

C: Q, 1% or less C is a strong austenite-forming element, and an increase in its amount contributes to improving strength, but on the other hand, it causes a decrease in corrosion resistance and toughness, so it is set to 0.1% or less.

Preferably it is 0.01 to 0.1%.

Si has the effect of increasing the hardenability of the alloy and improving the mechanical properties, but its most important role is as a deoxidizing agent. However, since a large amount of Ni will adversely affect the toughness, it should be kept at 1% or less.

Mn: 2% or less Mn has a deoxidizing effect and an effect of stabilizing the austenite phase, but if it exceeds 2%, it impairs corrosion resistance, so it should be kept at 2% or less.

Cr: 10-30% Cr has a remarkable effect on improving corrosion resistance, especially intergranular corrosion resistance, and is also effective on improving stress corrosion cracking resistance. It also contributes to stabilizing the tissue and improving its strength.

However, since Cr is a strong ferrite-forming element, the quantitative balance with the austenite-forming element should be considered, and addition of a large amount leads to a rapid decrease in toughness. From these points, the content is set to 10 to 30%.

MO2 8 to 18% MO is extremely effective in improving corrosion resistance, especially resistance to pitting corrosion and crevice corrosion, but when added in a large amount, it causes a rapid decrease in toughness, so it is set at 8 to 18%.

W: 6% or less W exhibits the effect of increasing corrosion resistance in coexistence with Mo. This effect can be obtained by adding 6% or less.

Ni: The remaining Ni is an austenite-forming element and is indispensable to ensure good corrosion resistance.

It also contributes to improving toughness.

Co-based alloy C: 0.1% or less, 5i11% or less, Mn: 2% or less,
An alloy consisting of Cr: 10 to 30%, Ni: 10 to 30%, and the remainder substantially Co, or one or two elements in which a part of Co is 20% or less of Fe, or 5% or less of Mo. Alloys substituted with

The reason for limiting the components of C, Si, Mn, and Cr in this Co-based alloy is the same as that in the Ni-based alloy. Other reasons for limiting ingredients are shown below.

Ni: 10-30% Ni is an austenite-forming element and is effective in improving the graininess of the alloy, and also contributes to improving the corrosion resistance. However, even if a large amount is added, the effect increases little compared to the amount added.

Therefore, it is set at 10 to 30%.

Mo: 5% or less Mo has a remarkable effect on improving corrosion resistance, particularly resistance to pitting corrosion and crevice corrosion, so it may be added in an amount of 5% or less if desired. 5
% is set as the upper limit because if it exceeds the upper limit, the effect of addition becomes almost saturated and embrittlement occurs.

Fe: 20% or less Although Fe is not a necessary element, it is allowed to be present in an amount up to 20%. Within this range, corrosion resistance will not be impaired.

CO: The remainder Go has an extremely strong effect on stabilizing the austenitic structure and provides excellent corrosion resistance.

〔Example〕

A mixed powder (granulated powder of 100 to 200 μm) of Ni-based alloy or Co-based alloy powder and ceramic powder (silicon carbide or chromium carbide, average particle size μm) is used as the welding material, and plasma powder overlay welding is performed. The following four types of test roll body members were manufactured by coating the surface of a metal sleeve (centrifugally cast carbon steel circular tube, outer diameter 220n) with a composite build-up layer of 4 layers thick, and the roll bodies were coated with the following four types. The shaft member was assembled to form a press roll, and each press roll was subjected to a paper separation test and a corrosion test, and the results shown in Tables 1 to 4 were obtained.

Incidentally, FIG. 2 graphically represents the relationship between the paper-separation evaluation in Tables 1 to 4 and the mixing ratio (wt%) of ceramic particles. Symbols (A) to (D) in the figure correspond to test rolls (A) to (D).

Combined overlay of nickel-based alloy + silicon carbide particles of test roll A Combined overlay of nickel-based alloy + chromium carbide particles of test roll B Combined overlay of cobalt-based alloy + silicon carbide particles of test roll C AJ cobalt-based alloy + chromium carbide particle nickel-based composition (wt%) C: 0.03, Cr: 15.3, Mn: 0.7,
si: 0.74, Mo: 14.2, W: 3.96,
Ni: Ba 1 cobalt-based alloy composition (%vt%) C: 0.05, Cr: 25. OlNi: 17.
5, Mn: 1.0, Si: 0.9, Fe: 15. O,
Mo: 1.7, Co: Bal.

CI) Paper separation test Each test roll was pressed against wet paper passing over a suction roll with a pressing force of 500 to 800 kg/cffl, and the adhesion to the surface of the test roll was compared with that of a conventional granite roll. do. The "U paper release resistance rating" in Tables 1 to 4 is a numerical value that expresses the paper release resistance of granite rolls with a standard value of "1", and the smaller the value, the better the paper release resistance. It means.

[■] Corrosion test A test piece was cut from the roll body of each test roll (A) to (D) and immersed in a boiling 2% hydrochloric acid solution. After 100 hours, the corrosion loss (g) of the composite overlay layer surface was measured. /mh) was measured.

As is clear from the above test results, the roll of the present invention having a surface made of a composite cladding layer exhibits paper release properties that are approximately equal to or better than conventional granite rolls. Furthermore, the loss of corrosion in boiling hydrochloric acid solution is also very slight, which indicates that the roll has sufficient corrosion resistance necessary for a press roll.

(Effects of the Invention) The press roll of the present invention has good paper separation properties equivalent to or better than conventional granite rolls, and has sufficient corrosion resistance for the environment in which it is used.
Since the body of the press roll of the present invention is a laminated structure of a metal sleeve and a composite overlay layer, it has superior strength and stability compared to granite rolls, and is used under repeated bending stress and thalassosing stress. At the bottom, stable durability that surpasses that of granite rolls is guaranteed. By using the press roll of the present invention, problems related to raw materials and manufacturing costs related to granite rolls are resolved, and at the same time, the dehydration process of wet paper is stabilized and
Various effects such as increased efficiency can be obtained.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view showing the press roll of the present invention, and FIG. 2 is a graph showing the relationship between the mixing ratio of ceramic particles in the composite overlay layer and the paper separating property. 10: roll body, 11: metal sleeve, 12: composite overlay layer, 20: roll shaft member.

Claims (1)

[Claims] (1) The surface of the roll body is coated with a build-up layer having a composite structure consisting of an austenitic nickel-based or cobalt-based alloy matrix mixed with 15 to 70% by weight of carbide ceramic particles as a dispersed phase. A press roll for paper making machines with excellent corrosion resistance and paper release resistance.