JPH0329862B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a so-called refiner member, which is a member that controls the beating of pulp fibers in a paper manufacturing process. The refiner member of the present invention is suitable for defibration and defibration of waste paper fibers, synthetic fibers, and animal fibers such as wool, as well as for defibration of virgin pulp fibers. Furthermore, the member of the present invention is also applicable to devices used for crushing grains, seeds, and the like. [Prior art] Pulp produced in the pulping process is sent to the papermaking process in a state dispersed in water, but paper made as is is often fluffy and has low strength, so it is usually not passed through the papermaking process. Prior to this, a beating process (beating the pulp to loosen it) is performed using a device called a refiner. Through this treatment, the outer layer of the fibers of the pulp is torn, the inner layer is exposed to water, and the water completely penetrates into the pulp, causing it to swell significantly. As a result, the fibers become significantly plasticized and flexible, allowing them to be easily deformed during the dewatering process of papermaking, and also improve the bonding strength between fibers. When the beating is further progressed, hair-like substances are generated on the surface of the fibers, which increases the ability of the fibers to intertwine with each other, strengthens the bonds between the fibers, and improves the strength. As described above, the beating treatment of pulp has a great influence on the properties of paper and plays an important role in the paper manufacturing process. Currently, there are two types of refiners used for this purpose: disk-type refiners and cone-type refiners. A conical refiner has a rotating plug (rotor) and its housing (stator) with longitudinally arranged metal bars, and the fibers are refined while flowing parallel to the bars. In addition, disc-type refiners include those that have a fixed disc and a rotating disc facing it, those that have two opposing rotating discs, and those that have two fixed discs and a rotating double-sided disc placed between them. . In any case, both the disc type and the conical type actually have teeth or grooves on the grinding surface that beats the fibers, and rotates at high speed (600 to 1200 rpm) to crush the pulp fibers. The mechanism is such that the uneven grinding surfaces pass through gaps that approach each other, thereby receiving the beating action. For this reason, the surface of the ground surface is required to have excellent chemical resistance (corrosion resistance) to water, as well as a high beating effect and excellent abrasion resistance. Incidentally, precipitation hardening stainless steel such as 17Cr-4NiPH copper is currently used as parts for refiners, but its wear resistance is not sufficient and it cannot be used continuously for 1 to 3 months. The teeth on the grinding surface were worn out and damaged, resulting in a significant deterioration in beating performance and had to be replaced. [Problems to be Solved by the Invention] The present invention advantageously solves the above-mentioned problems, and aims to provide a member for a refiner which has extremely excellent wear resistance as well as corrosion resistance. [Means for Solving the Problems] The present inventors have conducted extensive research to achieve the above object, and have found that a thermally sprayed coating of carbide-metal cermet or a metal base layer is applied to the ground surface of a refiner member. It has been found that forming a two-layer thermal spray coating consisting of a carbide surface layer and a carbide surface layer is extremely effective in achieving the intended purpose. That is, the coating thus obtained is much harder (Hv 1100-1300) compared to current materials;
In addition to having excellent corrosion resistance, the coating surface has fine irregularities that effectively hook the pulp fibers, resulting in a marked improvement in beating performance. The present invention is based on the above findings. That is, the present invention is a member that controls the disintegration and beating of pulp fibers containing moisture, and the grinding surface of the member is provided with a carbide-metal cermet spray coating, or a metal spray coating first layer and a carbide spray coating second layer. This is a refiner member equipped with a two-layer thermal sprayed coating consisting of: In this invention, carbides in the sprayed coating include WC, TiC, WC-TiC, Cr ₃ C ₂ , ZrC, TaC,
At least one selected from NbC, VC, B ₄ C and Mo ₂ C, and the metals include Co, Ni,
At least one selected from Ni-Cr and Ni-Al is each advantageously suited. Here, in the carbide-metal cermet spray coating of the first invention, the metal content in the coating is 5 to 5.
It is preferable to set it to 40wt% (hereinafter simply expressed as %). This is because if the metal content is less than 5 wt%, the adhesion between the sprayed coating and the object to be treated will be reduced, and the mutual bonding force of the film-forming particles will be reduced. On the other hand, if it exceeds 40%, the inherently high hardness of carbide and the surface function for beating fibers will deteriorate. The thickness of the carbide-metal cermet sprayed coating is preferably about 30 to 300 .mu.m.
This is because when the film thickness is less than 30 μm, there are many pores in the sprayed coating, and therefore the object to be treated is likely to be corroded.
On the other hand, if the thickness exceeds 300 μm, the residual stress of the sprayed coating becomes large and the adhesion to the object to be treated decreases, and the use of expensive sprayed materials causes a cost disadvantage. Next, in the two-layer thermal spray coating of the second invention, the metal coating thickness and the carbide coating thickness are respectively 10 to 10.
200 μm, preferably about 10 to 200 μm.
This is because if the metal coating thickness is less than 10μm,
The original undercoat action is insufficient. On the other hand, if the thickness exceeds 200 μm, the function as an undercoat will reach a saturated state and there will be no value in increasing the film. Further, if the carbide film thickness is less than 10 μm, the surface of the undercoat cannot be completely covered. On the other hand, if it exceeds 200 μm, it will only increase the cost and will have little effect in increasing the thickness as a refiner film. Further, the surface roughness of the outermost layer of the thermal spray coatings of the first and second inventions is preferably in the range of Ra 0.01 to Ra 5 μm. The reason for this is that with a surface roughness of Ra 0.01 μm or less, it requires a great deal of effort and expense to polish the surface, whereas with a surface roughness of Ra 5 or more, fiber adhesion becomes excessive and power costs increase due to increased water resistance. becomes larger. As the thermal spraying method, any conventionally known method can be used, such as an atmospheric pressure plasma spraying method, a reduced pressure plasma spraying method, and a thermal spraying method using a combustion flame of hydrocarbon gas as a heat source. FIG. 1a schematically shows the main parts of a disc-type refiner equipped with a refiner member according to the present invention. In the figure, numeral 1 is a rotating shaft, 2 is a rotating disk, and 3 and 4 are refiner members attached to the rotating disk 2 and a housing (not shown), respectively. These refiner members 3 and 4
In this example, a grinding surface is formed with a tooth-shaped uneven pattern on the surface, as shown in FIG. 5 is a thermally sprayed coating formed on the surface of the ground surface. 6 shows the flow of water containing pulp fibers, and the fibers are beaten while passing through the gap (usually about 0.1 to 1.0 mm) between the refiner members 3 and 4, which are tooth-shaped discs. Become. [Operation] The uneven pattern, such as a tooth pattern, formed on the surface of precipitation-hardened stainless steel, which is used as a conventional disc-shaped or conical refiner member, is a smooth metal surface when viewed microscopically. . Now, when water containing pulp fibers passes through the gap formed by the two tooth molds, the fibers are torn by the pressure of the two tooth molds.The fibers will easily slip on a smooth metal surface, and Since a large amount of coexisting water acts as a lubricant, the beating effect is extremely low. One possible solution to this problem is to narrow the gap between the two tooth impressions, but if the gap is made smaller, there will be more opportunities for the tooth impressions to come into contact with each other, resulting in mechanical damage to the tooth impressions. . In this respect, the surface of the carbide-metal cermet thermal spray coating according to the present invention has a state in which fine carbide particles are microscopically arranged in a forest and are fixed by metal, so that the adhesion efficiency of pulp fibers is high, and both Since there is little escape from the tooth pressure, the fibers are effectively beaten. Moreover, since the teeth of the refiner do not need to be particularly narrow, and an appropriate spacing is maintained, there is no risk of mechanical damage as seen with existing tooth forms. In addition, by increasing the rotational speed of the refiner, the contact resistance of the fibers attached to the surface of the sprayed coating with water increases, and this resistance alone can promote the fluffing phenomenon of the fibers, which improves the overall refining effect. will further improve. Furthermore, the carbide-metal cermet thermal spray coating of the present invention has good adhesion to the substrate, and also has corrosion resistance and
Its hardness is far superior to that of current precipitation-hardening stainless steels, so it does not peel off even when rotated at high speed underwater, and can be used stably for long periods of time. Above, we have mainly explained the case where a carbide-metal cermet thermal spray coating is formed.
Even in the case of a two-layer thermal sprayed coating structure consisting of a first layer and a second carbide sprayed layer, the same effect as described above can be obtained because the surface is made up of fine carbide particles. [Example] Example 1 Using the refiner shown in FIG. 1, an experiment was conducted under the following conditions. ● Experimental conditions (1) Tooth disc material: 17Cr-4Ni precipitation hardening stainless steel (JIS G4303 SUS 630) was used.
Finished with a hardness of Hv330-350. (2) Pulp fibers used and their concentration: water containing 5% virgin pulp fibers (3) Disk rotation speed: 800 rpm (4) Type of thermal spray coating: WC, TiC, WC-TiC,
_Cr3C2 , ZrC, TaC, NbC _, VC, _B4C , _Mo2C
Carbide-metal cermet (5) Thermal sprayed coating thickness: 100μm (6) Thermal sprayed coating surface roughness: Ra: 0.3 to 5μm ( 7) Comparative example SUS630 was used in an untreated state. A coating made of Al ₂ O ₃ , ZrSiO ₄ sprayed to a thickness of 100 μm A coating made of a Ni-Cr (80/20) alloy sprayed to a thickness of 100 μm Changes in tooth shape when the refiner was operated for 5 months under the above conditions The results of the investigation are shown in Table 1. During the operation period, after one month, and after three months, the effectiveness of the sprayed coating was evaluated by visually observing the tooth shape of the disk. Also,
Collect the fiber-containing water that has passed through the device, and use a magnifying glass to loosen the fibers contained in it.
The beating effect of the fibers was also evaluated by observing the condition. As is clear from the table, all of the refiner members (Nos. 1 to 10) coated with the carbide-metal cermet sprayed coating according to the present invention showed that the sprayed coating remained in a healthy state even after 5 months of operation. No change was observed in the shape of the teeth. In addition, the pulp fibers treated with the refiner member of the present invention are
It was well massaged and dispersed well in water.

[Table] The reason for this is that the refiner member according to the present invention has high hardness, so it will not be worn out even when it comes into contact with pulp fibers, and the fibers will adhere well to the fine irregularities on the surface of the coating, resulting in improved refining effects. This is thought to be the result of an increase in On the other hand, in the conventional untreated refiner member (No. 14), deformation was observed in the tooth profile after one month of operation, and significant deformation was observed after three months. Also, thermal spray coatings using oxide ceramics such as Al ₂ O ₃ (No. 11) and ZrSiO ₄ (No. 12) are
Adhesion to the base material was weak, and peeling was observed after one month of operation, and most of the coating peeled off after three months. This tendency was also observed in No. 13, which was thermally sprayed with Ni-Cr alloy, and the pulp fiber loosening effect was only low. The reason for this is that the surface of oxide ceramics and Ni-Cr alloy sprayed coatings is
This is thought to be because, microscopically, it is an aggregate of molten particles, so the adhesion effect of pulp fibers is weak, and therefore the beating effect is low. Example 2 Using the refiner shown in FIG. 1 above, experiments were conducted under the following conditions, and Table 2 shows the results of investigating changes in the shape of the teeth and the beating effect. ● Experimental conditions (1) Type of sprayed coating 1st layer: Co, Ni, Ni-Cr, Ni-Al 2nd layer: WC, TiC, WC-TiC, Cr ₃ C ₂ , ZrC,
TaC, NbC, VC, B ₄ C, Mo ₂ C (2) Sprayed coating thickness 1st layer: 80-100μm 2nd layer: 50-70μm (3) Surface roughness of sprayed coating: Ra0.3-5μm (4 ) Comparative example SUS630 was used in an untreated state. Coating made of Ni-Al alloy sprayed to a thickness of 150 μm (5) Evaluation items and methods: Same as Example 1

〔Effect of the invention〕

As described above, the refiner member according to the present invention has excellent pulp fiber refining action and can maintain its performance over a long period of time, thereby improving the pulp fiber refining efficiency and, in turn, improving the quality of the product. Ru. In addition, as the lifespan of refiner parts is extended, the plant can operate continuously, which greatly reduces complicated operations such as repairing refiner parts and replacing them with new parts, which helps reduce product manufacturing costs. can also be expected to be highly efficient.

[Brief explanation of the drawing]

FIG. 1a is a schematic diagram of the main part of a disc-type refiner equipped with a refiner member according to the present invention, and FIG. 1b is a sectional view of the grinding surface. 1... Rotating shaft, 2... Rotating disk, 3, 4... Refiner member, 5... Thermal spray coating, 6... Water flow containing pulp fibers.

Claims (1)

[Scope of Claims] 1. A member that controls the disintegration and beating of pulp fibers containing water, the ground surface of which has surface roughness.
1. A refiner member comprising a roughened carbide-metal cermet sprayed coating having an Ra in the range of 0.01 to 5 μm. 2 The carbides in the sprayed coating are WC, TiC, WC-
The refiner member according to claim 1, which is at least one selected from TiC, Cr ₃ C ₂ , ZrC, TaC, NbC, VC, B ₄ C and Mo ₂ C. 3. The refiner member according to claim 1, wherein the metal in the thermal spray coating is at least one selected from Co, Ni, Ni-Cr, and Ni-Al. 4. A member that controls disintegration and beating of pulp fibers containing moisture, and forms a two-layer thermal sprayed coating on the ground surface thereof, consisting of a lower metal sprayed first layer and an upper carbide sprayed second layer, A member for a refiner, characterized in that the second layer has a surface roughness Ra within a range of 0.01 to 5 μm. 5 The carbides in the sprayed coating are WC, TiC, WC-
The refiner member according to claim 4, which is at least one selected from TiC, Cr ₃ C ₂ , ZrC, TaC, NbC, VC, B ₄ C and Mo ₂ C. 6. The refiner member according to claim 4, wherein the metal in the thermal spray coating is at least one selected from Co, Ni, Ni-Cr, and Ni-Al.