JP3509262B2 - Manufacturing method of ceramic spray roll - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a ceramic sprayed roll used as a press roll in a press part of a paper machine.

[0002]

2. Description of the Related Art Wet paper removes most of its water content in the wire part, but since it still contains a considerable amount of water, a large amount of steam is required if it is immediately dried by heating in a dryer part. Entanglement is not sufficient and strength problems occur. Therefore, in the press part, the wet paper is mechanically squeezed to be dehydrated and then sent to the dryer part.

There are various types of press parts for a paper machine in relation to the thickness of paper and the speed of paper making. The straight through type as one of the types is, as shown in FIG. 4, an example of the straight through type, in which three combinations of an upper press roll 1 and a lower press roll 2 are lined up, and a first press 1P, a second press 2P, and a third press 3P is formed, and the wet paper web 3 sent from the upstream is passed together with the felt in the same direction in the first press 1P and the second press 2P, and the wet paper web 3 is changed in direction by the third press 3P and passed through the wet paper web. Only 3 is sent downstream through the smoother 4.

Further, the combined type as another type is
As shown in FIG. 5, one example thereof is a first press 1P formed by an upper press roll 5 and a lower press roll 6, and a press roll 7 used as a center roll is arranged beside the upper press roll 5 of the first press 1P. Then, the second press 2P is formed by the press rolls 5 and 7, the press roll 8 is arranged above the press roll 7 of the second press 2P, and the third press 3P is formed by the press rolls 7 and 8. Further, the fourth press 4P including the upper press roll 9 and the lower press roll 10 is provided downstream of the third press 3P.
And the wet paper web 3 sent from the upstream side together with the endless felt 11 appropriately wound around the presses 1P, 2P,
After passing through 3P and 4P in sequence, the smoother 4 is used to send out downstream.

The upper press roll 1 of each press 1P, 2P, 3P in the straight-through type press part
And second and third in combined type press parts
Since the press rolls 7 for the presses 2P and 3P and the upper press roll 9 of the fourth press 4P are required to have good wettability and releasability with respect to the wet paper web 3, conventionally, mainly crystals are extremely fine. A natural granite stone roll is used which has pores, excellent wetting characteristics, good wet paper peeling property, less flexibility, and less rust. Press rolls using such natural stone rolls
Usually, as shown in FIG. 6, a roll shell 1 made of natural stone
2 is formed, disk-shaped heads 13 are arranged on both end surfaces thereof, and both ends of a shaft 14 passing through the axial center of the roll shell 12 are projected through the both heads 13, A nut 15 is screwed to both ends of 14 and the nut 15 is tightened to form an integral roll shape.

However, when the natural stone roll is used as a press roll, if it is used at a high speed (1000 m / min or more) and a wide high nip (100 Kg / cm or more),
The stress acting on the roll shell 12 causes problems such as crack generation and breakage, and there is a drawback that it cannot withstand long-term use. Moreover, natural stone rolls have a limited number of natural stones worldwide. As a result, it is difficult to obtain the quality and it is difficult to guarantee the quality.

For this reason, ceramics spray rolls have been developed as an alternative technique to the above natural stone rolls.

[0008]

However, conventional ceramics spray rolls cannot withstand long-term use due to the phenomenon of peeling of the sprayed coating during use when a large pressure is applied. . Therefore, as a practical example of the conventional ceramics spraying roll, a downstream press roll such as the third press 3P in the straight through type shown in FIG. 4 and the fourth press 4P in the combined type shown in FIG. However, it was not used in the first press 1P or the press roll 7 as the center roll.

Therefore, when the cause of the above-mentioned peeling of the sprayed coating was investigated, it was found that cracks were generated between the layers forming the sprayed coating in the process of spraying the ceramic powder on the roll shell, and between the layers. It was found that the surface where cracks were present had a thin surface, causing the film to peel off during use. It is considered that this is mainly due to the thermal stress strain of the thermal spray coating.

Therefore, the inventor of the present invention, as a result of various experiments,
The present invention has been completed by finding that cracks do not occur between layers when the thickness of the layer forming the sprayed coating is smaller than a certain value. Therefore, the present invention is intended to provide a method for manufacturing a ceramic sprayed roll in which cracking does not occur between layers of the sprayed coating and peeling of the sprayed coating does not occur.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a surface treatment for the surface of a roll shell by applying an undercoat treatment.
A treatment layer is formed, a buffer layer is formed on the surface of the base treatment layer , and then the thickness of one pass is reduced to a range of 10 to 30 μm, and ceramic powder is multi-passed on the buffer layer. A method for manufacturing a ceramics sprayed roll, which comprises spraying to form a ceramics sprayed coating.

Further, at the time of spraying the ceramic powder, it is preferable to spray the ceramic powder while preheating the sprayed surface to 75 to 99 ° C. until the spraying is completed .

[0013]

[Function] The thickness of the ceramic powder to be sprayed is reduced to 10 to 30 μm per pass, and the ceramic powder is subjected to multiple passes.
Since the ceramics sprayed coating is formed by thermal spraying , thermal stress strain can be absorbed and cracks between layers of the ceramics sprayed coating can be prevented.

Further, when the ceramic powder is sprayed, by constantly preheating the sprayed surface, water on the sprayed surface can be removed, and at the same time, the temperature difference between the sprayed surface and the sprayed coating can be made small and residual stress can be kept small. You can do it.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1A and 1B show the outline of the manufacturing method of the present invention, in which both ends of the roll shell 16 made of cast steel having a required thickness and formed in a cylindrical shape have a central portion of an outer surface. A disk-shaped head 18 having a shaft 17 protruding therefrom is fitted and attached with a tightening bolt 19, whereby the roll main body 20
And the undercoat layer 22 is formed on the surface of the roll shell 16 of the roll body 20, and then the buffer layer 23 is formed.
And then, on the buffer layer 23, Al ₂ O
Multi-pass (multi-layer) thermal spraying of a ceramic powder obtained by adding 2% of TiO ₂ to _{3 is performed with} the thickness per pass being in the range of 10 to 30 μm so that the total finish thickness is 2-3 mm. The ceramic sprayed roll is manufactured by forming the ceramic sprayed coating 21.

Next, specific examples of the method for manufacturing a ceramic sprayed roll of the present invention will be described in detail.

First, the wall thickness is 30 to 90 mm and the diameter is 650.
mm, length 1955 mm, cast steel roll shell 16
The roll body 20 is constituted by
0 to one end of the roll shell 16 and the sample forming piece 24
(See Fig. 2). Next, in order to prevent the cast steel roll shell 16 of the roll body 20 from rusting, parts other than the surface portion of the roll shell 16 are masked, and the whole is put in a plating tank and electrolytic plating or the like is performed. Ni plating is applied to the surface of the roll shell 16, and after this Ni plating, the roll main body 20 is taken out of the plating tank, and the Ni-plated surface is shot blasted for undercoating to form an undercoating layer 22. To do. Note that the surface of the sample forming piece 24 is also subjected to the base treatment in the same manner as the surface of the roll body 20.

Next, the ceramic sprayed coating 2 applied as a top coating layer on the surface of the base treatment layer 22.
As the buffer layer 23 for absorbing the difference in thermal expansion between the roll shell 16 and the roll shell 16, for example, 95% Ni-5
% Al alloy is coated to the required thickness. This N
The thickness of the buffer layer 23 formed by i-Al coating is about 20% of the thickness of the ceramic sprayed coating 21 as the top coating layer.

After applying the buffer layer 23, the ceramic sprayed coating 21 is formed on the buffer layer 23 by using a spraying apparatus as shown in FIG. The above-mentioned thermal spraying device has a bearing 26 configured to rotatably support the shafts 17 at both ends of the roll body 20 horizontally arranged in the dust collecting chamber 25.
A driving device 27 that is connected to one shaft 17 to rotate the roll body 20, a spray gun 28 that sprays ceramic powder, and a servo motor 29 that drives the spray gun 28 in the horizontal direction. In addition, the traverser 30 and the like for traversing (reciprocating movement in the roll axis direction) is provided. In addition, 31 is a powder supply device, 32 is a powder supply control board, 33 is a traverser control board, 34 is a plasma generator control board, and 35 is a drive control board.

By using such a thermal spraying device, the roll main body 20
Is rotated by the driving device 27, and the buffer layer 2
On the surface of No. 3, while traversing the spray gun 28 with the traverser 30 in the horizontal direction, ₂ of TiO ₂ is added to Al ₂ O _3.
% Of ceramic powder added is 10 to 30 μm per pass, and the total finished thickness is 2 to
Gas plasma spraying is performed in multiple passes to form the ceramic sprayed coating 21 so as to have a thickness of about 3 mm.

In the above, the sample forming piece 24
The ceramic sprayed coating 21 is formed on the surface portion of the buffer layer 23 in the same manner as the surface portion of the buffer layer 23, and when the target finish thickness of about 1/3 is formed, the ceramic powder is once formed. Of thermal spraying is discontinued, the sample forming piece 24 is removed from the roll shell 16, the cross-sectional shape of the thermal spray coating formed on the sample forming piece 24 is checked, and if good, the ceramic powder is sprayed under the same conditions. Let it continue. On the other hand, if the cross section of the coating film checked is not good, the operation is stopped so that the production of defective products can be prevented.

As described above, in the present invention, the ceramic powder is sprayed at a thickness of 10 to 3 per pass (layer).
Since the thickness is made thin in the range of 0 μm, thermal stress strain can be absorbed. Therefore, no crack is generated between the layers of the ceramic sprayed coating 21.
Therefore, the obtained ceramic sprayed roll is
Also, even if it is used as a press roll at a position where a large pressing force is applied such as the first press 1P shown in FIG. 5, there is no concern that the ceramics sprayed coating 21 will peel off early. When spraying ceramic powder, the thickness per pass is 10 to 30 μm.
The reason why the range is set to 10 is that there is no problem in terms of absorption of stress strain even if it is less than 10 μm, but it takes a long time to obtain the finished thickness due to too many passes. This is because, when the thickness exceeds 30 μm, it has been confirmed by an experiment that the thickness of one layer is large and the stress strain becomes large and a crack is generated between the layers.

FIGS. 3 (a) and 3 (b) are cross-sectional photographs of the ceramic sprayed coating 21 as a result of the experiment conducted by the present inventor while changing the spraying conditions such as the thickness per pass. Indicates the spraying conditions, the rotation speed of the roll body 20 is 22 rpm, the powder supply amount is 40 g / min, and the feed speed of the spray gun 28 is 13
2 mm / min, 10 for thermal spray coating film thickness of 21 μm per pass
In the case of 0 pass (100 layers) thermal spraying, (b) is the thermal spraying conditions, the rotation speed of the roll body 20 is 22 rpm, the powder supply amount is 40 g / min, and the feed speed of the thermal spray gun 28 is 44 mm.
/ min, the spray coating thickness per pass is 64 μm, and 32 passes are sprayed. An experiment was conducted under these spraying conditions. As is clear from (a) and (b) of FIG. 3, ceramics per pass It was confirmed that when the thickness of the sprayed coating 21 was as thin as 21 μm, no cracks were generated between the layers, but when the thickness of the ceramics sprayed coating per pass was as thick as 64 μm, cracks were generated between the layers. . When the thickness of the thermal spray coating per pass is increased in this way, cracks occur between layers because the thermal residual stress becomes larger due to the temperature difference between the time of thermal spraying and the temperature after thermal spraying, and the adhesion strength between layers of thermal sprayed coating. This is because the cracks are likely to occur and cracks are likely to occur.

Next, another embodiment of the present invention will be described with reference to FIG. That is, in FIG. 2, the infrared heater 36 is provided on the outer side of the roll body 20 as indicated by a chain double-dashed line.
For example, three locations (only one is shown in the figure) are arranged at equal intervals in the circumferential direction, and the thermal spray surface is always preheated to 75 to 99 ° C. by the infrared heater 36 when the ceramic powder is sprayed. is there. In addition, the infrared heater 3
Instead of 6, an acetylene burner or the like may be used.

As described above, when the sprayed surface of the ceramic powder is always preheated to 77 to 95 ° C. until the spraying is completed, it is assumed that invisible moisture in the air is attached to the sprayed surface. It can also be removed, and if there is moisture on the sprayed surface, that portion will become voids during spraying, but by removing the moisture by preheating it can be prevented from becoming voids. it can. Further, since the temperature difference between the sprayed portion of the ceramic powder and the sprayed coating can be reduced by preheating, the thermal residual stress is reduced in combination with the reduction of the thickness of the ceramic sprayed coating 21. Can be eliminated or kept small. Therefore, the ceramic sprayed coating 21 can be made more difficult to peel off.

In the above description, the preheating temperature is set to 75 to 99 ° C. because the preheating effect is not exhibited at less than 75 ° C.
This is because the effect is the same as above.

[0028]

As described above, according to the method for manufacturing a ceramic sprayed roll of the present invention, the surface of the roll shell is
Surface treatment is performed to form a surface treatment layer, and the surface of the surface treatment layer
Forming a buffer layer on the
In addition, the thickness per pass is reduced to the range of 10 to 30 μm.
Multi-pass thermal spraying of ceramic powder
Since the coating is formed , thermal stress strain can be absorbed and cracks do not occur between layers. Therefore, even if it is used as a press roll of a paper machine press part where a large pressing force is applied, a ceramic sprayed coating Of the ceramic powder can be prevented .
At the time of spraying, the ceramic powder is sprayed while always preheating the sprayed surface to 75 to 99 ° C. until the spraying is completed , so that even if moisture adheres to the sprayed surface, it is removed and voids at that portion are removed. Can be prevented in advance, and the residual stress can be suppressed to be small by reducing the temperature difference from the sprayed surface during spraying, which makes it more difficult to peel the ceramic sprayed coating. In addition, the excellent effect of being able to provide a high quality ceramic sprayed roll is exhibited.

[Brief description of drawings]

FIG. 1 shows an outline of a method for manufacturing a ceramic spray-coated roll of the present invention, in which (a) is a schematic cross-sectional view and (b) is a partially enlarged view of (a) showing a ceramic sprayed coating portion.

FIG. 2 is a schematic view showing an example of a thermal spraying device used in the manufacturing method of the present invention.

FIG. 3 is a cross-sectional comparison of ceramic sprayed coatings made under different spraying conditions. (A) is a photograph of the metallographic structure of ceramic powder sprayed with a thickness of 21 μm per pass, (b) is 3 is a photograph of a metal structure in which ceramic powder is sprayed with a thickness of 64 μm per pass.

FIG. 4 is a schematic diagram of a straight through type showing an example of a press part.

FIG. 5 is a schematic view of a combined type showing another example of the press part.

FIG. 6 is a schematic sectional view of a natural stone roll.

[Explanation of symbols]

16 roll shell 21 Ceramics sprayed coating 22 Undercoat layer 23 Buffer layer 28 Thermal spray gun 36 infrared heater

Claims (2)

(57) [Claims] 1. A surface of a roll shell is surface- treated to form a base.
A treatment layer is formed, a buffer layer is formed on the surface of the base treatment layer , and then the thickness of one pass is reduced to a range of 10 to 30 μm, and ceramic powder is multi-passed on the buffer layer. A method for manufacturing a ceramic sprayed roll, which comprises spraying to form a ceramic sprayed coating. 2. When spraying ceramic powder , the sprayed surface is
The method for manufacturing a ceramics spray roll according to claim 1, wherein the ceramics powder is sprayed while being preheated to 75 to 99 ° C. until the spraying is completed .