JPH06166982A - Dehydrating unit for papermaking machine - Google Patents

Abstract

PURPOSE:To provide the subject dehydrating unit good in resistance to corrosion and wear. CONSTITUTION:The objective dehydrating unit is so designed as to slide with one surface of a papermaking wire to control the dehydration from the pulp liquor on the other surface. The part to be contacted with the papermaking wire consists of an alloy prepared by calendering and heat-treating an Ni alloy having a composition comprising 14-23wt.% of Cr, 14-20wt.% of Mo, 0.2-5wt.% of W, 0.2-7wt.% of Fe, 0.2-2.5wt.% of Co and the balance Ni with inevitable impurities. By this constitution, sufficient hardness of this alloy can hold high wear resistance and corrosion resistance against sulfates and sodium hydroxide in pulp liquor. Besides, as the alloy has been put to intense calendering, its structure is fine, leading to little wearing of the papermaking wire as the counterpart for sliding. Furthermore, because the alloy is a material obtained by calendering, a continuous material can easily be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dewatering unit provided in a wire part of a paper machine for promoting or suppressing dewatering from pulp liquor. In particular, it is excellent in corrosion resistance and abrasion resistance and is used for papermaking. The present invention relates to a dehydration unit that does not easily wear a wire.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional fourdrinier paper machine. Reference numeral 2 is an endless paper making machine commonly called a paper making wire. The wire is formed by forming a bronze wire, a plastic wire, or the like into a warp or weft in a mesh shape, and is stretched between the breast roll 4 and the coach roll 6.

A head box 8 is provided above the breast roll 4, and pulp liquid is jetted onto the surface of the wire 2 from a nozzle 10 called a slice lip of the head box 8. The pulp liquid is
A slurry in which fine mineral powders called pulp fibers and fillers are dispersed in water.

Then, the water in the pulp liquid jetted onto the surface of the wire 2 (the upper surface in the drawing) is extracted from the surface (rear surface) on the opposite side of the wire 2 to form a pulp layer on the surface of the wire 2. Are formed. In addition, when the formed pulp layer reaches the coach roll 6, it is sent to the pressing step of the next step, water is squeezed, and further a drying step,
It is designed to be sent to the coating process. A tank 12 called saveall is provided below the wire 2 to collect white water (slurry containing fine pulp fibers, filler, etc.) discharged from the back surface of the wire 2. .

The above paper machine is provided with various dewatering units for controlling dewatering from the pulp liquid on the wire 2. Reference numeral 14 is a forming board, and the forming board 14 limits the dehydration from the pulp liquid to a certain level or less by coming into contact with the back surface of the wire 2. That is, the forming board 14 is usually provided with a hole penetrating in the thickness direction, and the dehydration amount is increased by increasing the opening ratio of this hole,
Further, the dehydration amount can be reduced by reducing the aperture ratio.

Reference numeral 16 is a hydrofoil, and this hydrofoil 16 promotes dehydration by making line contact with the back surface of the wire 2 and scraping off water droplets, and between the surface and the back surface of the wire 2. It has a function of generating a negative pressure and promoting dehydration of the back surface of the wire 2.

Reference numeral 18 is a suction foil,
By enclosing the periphery of the hydrofoil 16 that contacts the back surface of the wire 2 and applying a negative pressure, a stronger dewatering action is performed.

Further, reference numeral 20 is a suction box, and this suction box 20 has many through holes like the forming board 14, and a negative pressure is applied to the back surface of the wire 2 through these through holes. , Has done even more powerful dehydration.

The reason for using a wide variety of dewatering units as described above depends on the quality of the paper depending on the dewatering mode of the wire 2 (in which range slow dewatering is performed and in what range rapid dewatering is performed). This is because that. Generally, the dehydration in the initial stage before the formation of the pulp layer on the surface of the wire 2 is as slow as possible, and after the dehydration has progressed to a certain extent and the pulp layer is formed on the wire and stabilized, the dehydration should be as strong as possible. It is considered ideal.

FIG. 4 shows a conventional example of a twin wire type paper machine. In this paper machine, the first wire 2
2, the pulp liquid is supplied from the nozzle 28 of the head box 26 between the second wires 24.

Even in the twin wire type paper machine, the forming board 30 or the wires 22 and 24 which are dehydrated by the centrifugal force by running both the wires 22 and 24 while curving to a predetermined radius of curvature. A dewatering unit such as a hydrofoil (also referred to as a deflector) 32 that promotes dewatering from the back surface of the pulp is provided so that dewatering from the pulp liquid is performed according to a predetermined dewatering mode.

[0012]

Since the above pulp liquid contains residual components of the chemical liquid such as sulfate and caustic soda used in producing pulp from wood, it may corrode metals, and Since the filler is an additive consisting of clay, talc, minerals such as calcium carbonate,
A wrapping action will be performed on an object that comes into contact with it. Therefore, the various dewatering units used under the environment in which the pulp liquid containing such a component intervenes is required to have corrosion resistance and wear resistance. Ceramics such as silicon and silicon carbide are used.

By the way, for the purpose of improving the productivity of the above paper machine, its width dimension (dimension in the direction orthogonal to the paper surface of the drawing) tends to be large.
It can be up to 7 meters.

However, it is not easy to manufacture such a long product from a single piece of ceramics, and it is generally necessary to adopt a structure in which a large number of ceramic segments having a width of several tens of centimeters are arranged in the width direction. Absent. In addition, in such a structure, continuity in the width direction is lost at the joint between the segments, so that abnormal wear occurs on the wire at this portion, and the quality profile (moisture density, density ) May cause non-uniformity. In addition, as a material used for such an application, stainless steel or a material obtained by welding a hard material such as cemented carbide on its surface can be considered, but stainless steel has insufficient wear resistance and Since alloys have insufficient corrosion resistance, they must be replaced or re-polished at short intervals, which means that they are unsuitable materials for paper machines that are assumed to be in continuous operation.

The present invention has been made in view of the above circumstances, and provides a dewatering unit capable of producing paper having excellent wear resistance and corrosion resistance and having a uniform profile in the width direction. With the goal.

[0016]

In order to achieve such an object, the invention of claim 1 slides on one surface of the papermaking wire to remove the pulp liquid from the other surface of the papermaking wire. A dehydration unit for controlling dehydration, wherein Cr: 14 to 23%, Mo: 14 to 20%, W: on the surface of the contact portion with the papermaking wire in the dehydration unit.
0.2-5%, Fe: 0.2-7%, Co: 0.2-
It is characterized by comprising an alloy obtained by rolling and heat treating a Ni alloy having a composition of 2.5%, balance Ni and unavoidable impurities. The invention of claim 2 relates to claim 1
The dehydration unit according to the invention is characterized in that it is a hydrofoil having a sharp edge that comes into line contact with one surface of the papermaking wire. The invention of claim 3 is characterized in that the dewatering unit in the invention of claim 1 is a forming board that comes into surface contact with one surface of the papermaking wire. The invention of claim 4 is characterized in that a through-hole is provided which penetrates in the thickness direction of the dehydration unit of the invention of claim 1.

[0017]

The dewatering unit of the present invention contains a hard filler and a corrosive sulfate or caustic soda because the Ni-Mo intermetallic compound is finely and uniformly dispersed in the Ni alloy matrix. It has sufficient corrosion resistance and wear resistance in a use condition where it slides on a wire under the condition of pulp liquid intervening. Further, since it can be manufactured by rolling, a long product having the same cross section can be easily manufactured.

[0018]

FIG. 1 shows an embodiment of a hydrofoil to which the present invention is applied. Reference numeral 40 denotes a base formed of a plastic material such as high-density polyethylene, and a blade 42 made of the nickel alloy according to the present invention is attached to a part of the surface of the base. The base 40 is supported by a frame 43 provided across the width of the paper machine in the width direction (direction orthogonal to the wire advancing direction shown by the arrow in FIG. 1), and between them, there is a dovetail 46 and An engagement structure including the dovetail groove 48 is adopted. Therefore, in the hydrofoil of FIG.
Can be integrally drawn out or inserted along the width direction of the paper machine. Further, since the base 40 is made of a relatively lightweight plastic material, it can be easily handled by a worker.

In the illustrated case, projections 50 for engagement are provided on the bottoms of the blades 42, respectively.
The blade 42 is fixed to the base 40 by being pressed into 2. In addition, a through hole (omitted in FIG. 1) is provided in the blade outside the range where the pulp liquid is supplied (or both ends in the width direction that are not cut into so-called ears and thus do not affect the quality of the product). A bolt may be inserted into the through hole and fixed by screwing the bolt into the base 40. Further, in the illustrated case, the blade 42 is provided only at the tip portion including the sharp edge portion that makes line contact with the wire 2 and the area that makes surface contact due to the deflection of the wire 2 (the portion that is deflected downward by gravity and negative pressure). However, it goes without saying that it may be provided so as to cover the entire upper surface of the base 40.

FIG. 2 shows an embodiment of a suction box to which the present invention is applied. Reference numeral 54 is a top board made of the nickel alloy of the present invention.
The top board 54 is provided so as to cover the upper opening of the box main body 56 having a U-shaped cross section. The box main body 56 is made of stainless steel or the like, and has a suction port 58 connected to a negative pressure source such as a turbo blower or a vacuum pump on the side thereof, and the bottom thereof has an internal storage. Drainage outlet 60 for discharging white water
Is provided. A large number of through holes 62 are provided in the top board 54, and a negative pressure is applied from the inside of the box to the lower surface of the wire 2 through the through holes 62 to dehydrate the pulp liquid on the surface of the wire. It is supposed to do. Instead of forming the entire topboard 54 with the Ni alloy of the present invention as shown in the figure, the surface (the range of sliding with the wire) may be covered with a thin plate of Ni alloy. The forming board used in the paper machine as one of the dewatering units has almost the same structure as the top board 54 of the suction box, and therefore the required dewatering capacity (usually much smaller than that of the suction box). ) Depending on the through hole 6
It can be obtained by changing the aperture ratio and plane shape of No. 2 or making the sliding surface with the wire a predetermined radius of curvature.

Next, the nickel alloy forming the blade 42 and the top board 54 will be described. This alloy has corrosion resistance to sulfates and caustic soda contained in pulp liquor, and hardness sufficient to obtain wear resistance to sliding with wires in white water containing mineral filler. There is. That is, in weight% Cr:
14-23%, Mo: 14-20%, W: 0.2-5
%, Fe: 0.2 to 7%, Co: 0.2 to 2.5%, Ni alloy ingot having a composition consisting of balance Ni and unavoidable impurities, hot forged and hot rolled under normal conditions. The hot rolled material is subjected to normal conditions (1100
The solution treatment is performed at a temperature of up to 1200 ° C to form an austenite structure. Then, in the state of austenite structure, cold working gives a plastic working rate of 70% or more, preferably 80% or more, and then this is carried out at 450 to 800 ° C, preferably 500 to 600 ° C, 0.3 By holding for at least an hour, preferably at least 0.5 hour, fine Ni-
A Mo-based intermetallic compound can be deposited in the matrix.

Next, the reasons for limiting the components and manufacturing conditions of the alloy having the above composition as described above will be explained. A. Component composition a) Cr The Cr component has a function of significantly improving the passivation ability of the austenite matrix and improving the corrosion resistance, but if the content thereof is less than 14%, the corrosion resistance particularly in an oxidizing atmosphere is When the content exceeds 23%, the austenite structure becomes unstable and a structure in which fine Ni-Mo intermetallic compounds are precipitated in the austenite matrix can be stably formed. It becomes impossible to do so, and it causes a decrease in corrosion resistance.
Limited to ~ 23%.

B) Mo Mo The Mo component has a function of improving strength by forming a Ni-Mo intermetallic compound which is finely and uniformly precipitated in the matrix as described above by binding with Ni. When the content is less than 14%, the desired effect cannot be obtained. On the other hand, when the content exceeds 20%, the hot and cold rolling properties are deteriorated. Limited to 20%.

C) WW component has the action of forming a solid solution in the austenite matrix to improve the strength, but if its content is less than 0.2%, the desired strength-improving effect cannot be obtained. 5% content
If it exceeds 1.0, the hot and cold rolling properties will be deteriorated, so the content was limited to 2 to 5%.

D) Fe Fe component has an effect of improving hot and cold rolling properties, but if its content is less than 0.2%, the desired effect cannot be obtained on the other hand. If the amount exceeds 7%, the strength will decrease, so the content is set to 0.
It was limited to 2 to 7%.

E) Co The Co component has the function of forming a solid solution in the austenite matrix and stabilizing it to stabilize the precipitation of the intermetallic compound during the precipitation hardening treatment, but its content is 0.2%. If it is less than 0.2%, the effect is not obtained. On the other hand, even if the content exceeds 2.5%, no further improvement effect is exhibited by this effect. Limited to ~ 2.5%.

B. Manufacturing conditions a) Cold rolling ratio If the cold rolling ratio is less than 70%, precipitation of the intermetallic compound by precipitation hardening after cold rolling is not sufficiently performed, and in this case, H
Since it is not possible to obtain a hardness of 48 or more in RC, the cold rolling rate is limited to 70% or more. Further, particularly when the cold rolling rate is 80% or more, a hardness of 56 or more in HRC is obtained, which is more preferable. When performing this cold working, the cold rolling mill is used so that the total rolling reduction (working rate) is 70% (80%) or more at a rolling reduction of 3 to 4% per pass. When the hot rolling is continued, a thin plate of Ni alloy is obtained. The thin plate at this stage has a hardness of 45 (50) or more in HRC due to work hardening. The processing rate is 95
% Or more is more preferable. Ni with the above composition
Processing of the alloy at a processing rate of 95% or more can be easily carried out by using a roll made of cemented carbide. A thin plate having an HRC of 60 or more can be obtained by processing to 95% or more in this way and performing precipitation hardening treatment as described later.

B) Precipitation hardening treatment If the above-mentioned thin plate is held at a temperature of 450 to 800 ° C for 0.3 hours or more, the intermetallic compound is deposited and the HRC hardness becomes 48 or more. Here, if the treatment temperature is less than 450 ° C, it takes a long time to precipitate the intermetallic compound, which is not preferable in terms of productivity. On the other hand, if the treatment temperature exceeds 800 ° C, an alloy that forms a solid solution in the austenite matrix is formed. Since the ratio of the components is increased, the precipitation of the intermetallic compound cannot be satisfactorily performed, and the hardness of 48 or more cannot be obtained by HRC. Therefore, the temperature is limited to 450 to 800 ° C.
Further, particularly, if the above-mentioned thin plate is held at a temperature of 500 to 600 ° C. for 0.5 hour or more, a material having a high hardness of HRC 56 or more is obtained, which is more preferable.

Next, a specific method of manufacturing a dehydration unit using the above Ni alloy will be described. First, a high-frequency induction furnace was used to prepare molten Ni alloys having the composition shown in Table 1 below, and the diameter was 150 mm and the length was 4 mm.
Cast a 00 mm ingot. 1 for this ingot
Hot forged at a starting temperature of 200 ° C to a thickness of 5
A plate material of 0 mm is obtained, and this plate material is subjected to hot rolling at a starting temperature of 1200 ° C to obtain a hot rolled material having a thickness of 20 mm,
Next, this hot rolled material was subjected to solution treatment under the condition of holding it at 1150 ° C. for 2 hours, and then subjected to cold working at the rolling rate also shown in Table 1, followed by the same conditions as shown in Table 1. By performing the precipitation hardening treatment in 1., the production methods 1 to 15 of the present invention were performed to produce the blade of FIG.

Further, the tensile strength, hardness (HRC) and corrosion resistance of the blade obtained as described above were measured, and the measurement results are shown in Table 1. In addition, Table 1 shows, as a comparative example, the results of the same type of experiment for cemented carbide and stainless steel. In addition, the corrosion resistance was measured by using the ferric chloride corrosion test method for stainless steel of JIS G 0578.

[0031]

[Table 1]

As is clear from Table 1, the products of the present invention 1 to 1
Each of the dehydration units manufactured by No. 5 has higher strength than conventional metal materials, and also has no significant weight loss in a corrosive environment, and has an extremely high corrosion resistance. You know that you have. On the other hand, the conventional cemented carbide products have higher hardness than the products of the present invention, but have low strength, and a considerable weight loss is observed in terms of corrosion resistance, and the corrosion resistance is greatly inferior. ing.

The kind or specific shape of the dehydration unit to which the Ni alloy of the present invention can be applied is not limited to the above-mentioned embodiment, and for example, a predetermined radius of curvature for a twin wire type paper machine. It is needless to say that the present invention can be applied to a forming board having a curved shape and a hydrofoil whose upper surface is inclined at different angles in order to obtain different dewatering performance.

[0034]

As described above, the dehydration unit using the Ni alloy of the present invention has the following effects. I. Since it has sufficient hardness, it can exhibit sufficient abrasion resistance against the lapping action of the pulp liquid. B. Sufficient corrosion resistance can be exhibited against the sulfate and caustic soda contained in the pulp liquid. C. Since it is subjected to the strong rolling treatment, its structure is fine and uniform, so that the papermaking wire that slides with the dehydration unit is less likely to wear. D. It is a material obtained by rolling treatment, and since this rolling treatment is generally performed continuously using rolls,
A long material can be easily obtained, and therefore, it can be easily applied to a dehydrating unit of a wide paper machine.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a hydrofoil according to an embodiment of the present invention.

FIG. 2 is a transverse sectional view of a suction box according to another embodiment of the present invention.

FIG. 3 is a side view showing an example of a conventional fourdrinier paper machine.

FIG. 4 is a side view showing a conventional example of a twin wire type paper machine.

[Explanation of symbols]

2 wire 40 base 42
Edge 54 Top board 56 Box body 6
2 through holes

Claims (4)

[Claims] 1. A dewatering unit for controlling dewatering from the pulp liquid on the other surface of the papermaking wire by sliding on one surface of the papermaking wire, wherein the papermaking wire in the dewatering unit. The contact area with Cr is 14:
23%, Mo: 14 to 20%, W: 0.2 to 5%, F
e: 0.2 to 7%, Co: 0.2 to 2.5%, balance Ni
A dewatering unit for a paper machine, which is made of an alloy obtained by subjecting a Ni alloy having a composition of unavoidable impurities to rolling and heat treatment. 2. The dewatering unit for a paper machine according to claim 1, wherein the dewatering unit is a hydrofoil having a sharp edge in line contact with one surface of the papermaking wire. 3. The dewatering unit for a paper machine, wherein the dewatering unit is a forming board that comes into surface contact with one surface of a papermaking wire. 4. A dewatering unit for a paper machine, wherein the dewatering unit is provided with a hole penetrating in a thickness direction thereof.