JP2000248485A - Roll-supporting device in paper machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roll-supporting device in a paper machine, hardly suffering surface damage to a raceway surface of a bearing even in a high temperature environment and capable of securing a long durable life. SOLUTION: At least an inner ring 11 and an outer ring 13 of a self-aligning roller bearing for supporting a roll neck part 3 of a drier roll are composed of a steel material containing >=0.3 and <=3.0 wt.% Si, >=0.1 and <=3.0 wt.% Ni, >=0.05 and <=1.0 wt.% V, and >=0.05 and <0.25 wt.% Mo singly or in combination, and formed so that the surface hardness may be >=58 HRC of Rockwell hardness to make the material and the surface hardness after the hardening and tempering processes excellent in rolling fatigue characteristics and surface damage resistance, stable even at high temperature, and to elongate endurance life of the roll-supporting device used in a high temperature environment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supporting device for rotatably supporting a dryer roll or the like of a paper machine by a double row roller bearing.

[0002]

2. Description of the Related Art In general, a paper machine is provided with a crossing section, a press section,
It consists of a drying section and a finishing section, and various rolls are arranged in each section. As an example of these rolls, a dryer roll in a drying section will be described.

[0003] A large number of dryer rolls are arranged in a staggered manner in the drying section, and wet paper squeezed and dewatered by the press rolls of the press section is wound around these dryer rolls, dried, and dried in the finishing section. Conveyed. FIG. 1 shows the structure of a dryer roll according to an embodiment of the present invention. This dryer roll comprises a cylindrical roll body 1 and a pair of roll necks 3 and 4 having end plates 2 for sealing both ends of the roll body 1, and each roll neck 3 and 4 has a double-row automatic roll. It is rotatably supported by an aligning roller bearing 5.

[0004] At the center of the roll body 1, a steam inlet pipe 6 for internally heating a dryer roll is piped through one roll neck 3. A large number of holes 7 are provided in the steam introduction pipe 6. Water condensed from the holes 7 and heated to heat the roll body 1 is pumped up by a pumping car 8 and passed through the roll neck 3. The waste water is discharged to the outside by a drain pipe 9. Pumping car 8
There is also a dryer roll using a siphon instead of.

FIG. 2 shows an enlarged view of the bearing on the roll neck 3 side. The self-aligning roller bearing 5 includes an inner race 11 having a double row of raceways 10 on the outer peripheral surface, and a spherical raceway 12 on the inner peripheral surface.
A double row roller 14 is rotatably held by a retainer 15 between outer races 13 having outer races 13.
Is fitted on the inner peripheral surface of the housing 16, and the inner race 11 has a tapered hole on the inner peripheral side, and is fitted to the roll neck 3 via a tapered sleeve 17.

Since the above-mentioned dryer roll is internally heated by high-temperature steam, the temperature of the roll neck also rises,
The supporting device of the dryer roll is used in a high temperature environment.
The bearing rings and rollers of the double row roller bearings of these roll supporting devices are made of quenched SUJ2 or SUJ3 high-carbon chromium bearing steel. Tempered at a higher temperature than the operating temperature.

[0007]

As described above, a double row roller bearing of a roll supporting device such as a dryer roll of a paper machine is used in a high temperature environment, so that an oil film is hardly formed on a raceway surface, and peeling and the like are difficult. Surface damage such as smearing may be a problem. In addition, when a self-aligning roller bearing having a tapered hole is employed in the double row roller bearing, the inner ring is fixed with a relatively high fitting stress, so that the value of the repetitive stress due to the rolling of the roller is increased, and the inner ring is increased. May have a shortage of rolling fatigue characteristics, and a short service life of the roll supporting device may be a problem.

It is an object of the present invention to provide a roll supporting device for a paper machine which is less likely to cause surface damage on a raceway surface of a bearing even in a high-temperature environment and can secure a long durability life.

[0009]

In order to solve the above-mentioned problems, the present invention relates to a roll supporting device for a paper machine in which a roll is rotatably supported on a housing by a double row roller bearing. Is contained by mass% as an alloying element and contains Si in an amount of 0.3% or more and 3.0% or less,
And Ni is 0.1% or more and 3.0% or less, and V is 0.0% or more.
5% or more and 1.0% or less, Mo is 0.05% or more and 0.1% or less.
A steel material containing less than 25%, alone or in combination, was used, and the surface hardness was set to Rockwell hardness HRC 58 or more.

[0010] The alloy element of the steel material forming at least the bearing ring of the bearing contains Si in an amount of 0.3 to 3.0% because Si suppresses softening in a high temperature range and has a heat resistance of a rolling bearing. This is because there is an effect of improving the properties. 0.3%
When the content is less than 3.0%, the effect is saturated, and the effect is saturated, and the hot workability and the coating property are deteriorated. Since the machinability is reduced, the upper limit is limited to 3.0%.

Ni is 0.1-3.0%, V is 0.05-
The reason for containing 1.0% and Mo individually or in combination of 0.05 to less than 0.25% is as follows.

Ni forms a solid solution in steel to strengthen the matrix, suppresses the structural change in the rolling fatigue process, especially when the bearing is used at a high temperature, and has a hardness in a high temperature range. Is also suppressed. Therefore, Ni has an effect of improving rolling fatigue characteristics and surface damage resistance under a high temperature environment. In order to obtain these effects, it is necessary to contain Ni in an amount of 0.1% or more. Therefore, the lower limit when adding Ni is set to 0.1%. However, N exceeds 3.0%
When i is contained, a large amount of retained austenite is generated during the quenching treatment, so that a predetermined hardness cannot be obtained,
In addition, since the cost of steel material becomes high, the upper limit is limited to 3.0%.

V combines with carbon to precipitate fine carbides, refines crystal grains to improve strength and toughness, suppresses softening during high-temperature tempering, and also suppresses softening in high-temperature regions. I do. Therefore, like Ni, V has the effect of improving rolling fatigue characteristics and surface damage resistance under a high temperature environment. In order to obtain this effect, the lower limit of the V content is set to 0.05%. The reason why the upper limit is limited to 1.0% is that when V is contained in a large amount exceeding 1.0%,
This is because machinability and hot workability are reduced.

Mo improves the hardenability of steel, prevents temper embrittlement, and also suppresses softening at high temperatures. Therefore, Mo also has an effect of improving rolling fatigue characteristics and surface damage resistance under a high temperature environment. In order to obtain this effect, the lower limit of the Mo content is set to 0.05%. M
When the o content is 0.25% or more, the machinability decreases and the cost of steel material also increases. Therefore, the upper limit is limited to less than 0.25%.

Even if the bearing is tempered at a high temperature by the action of each of the alloy elements described above, the surface hardness of the bearing is set to Rockwell hardness HRC 58 or more, thereby preventing surface damage such as peeling and smearing. Generation can be prevented.

In the steel material, M
By adding n at 0.2% or more and 1.5% or less and Cr at 0.3% or more and 5.0% or less, the rolling contact fatigue properties and surface damage resistance of the bearing can be further improved. .

That is, both Mn and Cr improve the hardenability of the steel material, Mn forms a solid solution in the steel to strengthen the steel, and Cr forms carbides to strengthen the steel. The lower limit of the Mn content is set to 0.2% and the lower limit of the Cr content is set to 0.3% in order to obtain these effects. Further, the upper limit of the Mn content is limited to 1.5% in order to avoid a decrease in machinability, and the upper limit of the Cr content is limited to 5.0%, because the formation of large carbides is restricted. This is to prevent embrittlement due to

By forming a carbonitrided layer at least on the surface layer of the bearing ring of the bearing and making the amount of retained austenite of the carbonitrided layer 10% by volume or more, high toughness is imparted to the surface layer of the bearing ring. The generation and propagation of cracks can be suppressed, and the durability life of the roll support device can be further extended.

That is, when the nitrogen content of the surface layer is increased by the carbonitriding treatment, the Ms point (martensite transformation start temperature) of the surface layer is lowered, and when this is quenched, untransformed austenite is increased in the surface layer. Remains. Retained austenite has high toughness and work hardening characteristics, and functions to suppress the generation and propagation of cracks. In the surface layer having a lowered Ms point, the martensitic transformation starts later than the inside and the amount of transformation is smaller than the inside, so that residual compressive stress is formed in the surface layer and the fatigue strength of the surface layer is improved. I do.
The reason why the amount of retained austenite in the carbonitrided layer is set to 10% by volume or more is to obtain these effects. On the other hand, since the amount of retained austenite is reduced by high-temperature tempering, the dimensional change due to decomposition of the retained austenite during use can be suppressed.

The roll supporting device is preferably applied to a dryer roll.

As the inner race of the double row roller bearing, a race fitted to the neck portion of the roll with a tapered hole can be adopted. Further, as the double row roller bearing, a self-aligning roller bearing can be adopted.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a dryer roll of a paper machine using the roll supporting device of the present invention. This dryer roll has a cylindrical roll body 1 as described above,
The roll body 1 includes a pair of roll necks 3 and 4 each having a head plate 2 that seals both ends of the roll body 1.
Are rotatably supported by double row self-aligning roller bearings 5.

At the center of the roll body 1, a steam introduction pipe 6 for internally heating the dryer roll is piped through one roll neck 3. A large number of holes 7 are provided in the steam introduction pipe 6. Water condensed from the holes 7 and heated to heat the roll body 1 is pumped up by a pumping car 8 and passed through the roll neck 3. The water is discharged to the outside through the drain pipe 9.

FIG. 2 shows an enlarged view of the bearing on the roll neck 3 side. The self-aligning roller bearing 5 includes an inner race 11 having a double row of raceways 10 on the outer peripheral surface, and a spherical raceway 12 on the inner peripheral surface.
, A plurality of rows of barrel-shaped rollers 14 are rotatably held by retainers 15 between outer races 13 having outer ring 13.
6, the inner race 11 has a tapered hole on the inner peripheral side, and is fitted to the roll neck 3 via a tapered sleeve 17, and the tapered sleeve 17 is
Is fixed in the axial direction. The bearing on the roll neck 4 side has the same configuration.

The inner race 11 and the outer race 13 are made of steel having the chemical composition shown in the following Table 1 as an embodiment, and
After heating to 0 ° C to 860 ° C, quenching into a salt bath, 35
Tempered at 0 ° C. In some examples, heating before quenching was performed in a carburizing atmosphere to which ammonia gas was added, and carbonitriding was also performed. The tempering temperature of the carbonitrided steel was 230 ° C.

The inner ring 1 of the self-aligning roller bearing 5 of the above embodiment
1 and outer ring 13 are the result of the inspection by sample extraction,
All of them had a surface hardness of Rockwell hardness HRC 58 or more, and those subjected to carbonitriding had an amount of retained austenite in the carbonitrided layer of 10% by volume or more.

[0027]

[Table 1]

Examples and comparative examples will be described below.

[0029]

EXAMPLES Test pieces and inner rings (Examples 1 to 6 in Table 1) which had been subjected to the above-mentioned quenching and tempering treatment were prepared from steels having the six chemical components shown in Table 1 as raw materials. Example 1
Test pieces and inner rings (Examples 7 and 8 in Table 1) in which some of the steel materials shown in FIG. 6 were carbonitrided were also prepared.

[0030]

[Comparative Example] Test pieces and inner rings (Comparative Examples 1 to 4 in Table 1) prepared by quenching and tempering high carbon chromium bearing steels SUJ2 and SUJ3 and steels having two kinds of chemical components out of the chemical component range of the present application are prepared. did. As for the material using SUJ2, a test piece and an inner ring (Comparative Example 5 in Table 1) which were also subjected to the carbonitriding treatment were prepared.

With respect to any of the test pieces and the inner rings of the above Examples and Comparative Examples, a dimensional stability test, a peeling test, a smearing test, and a rolling fatigue test under a high fitting stress were performed.

The outline and results of each test are as follows.

(1) Dimensional Stability Test The inner ring that had been tempered at 350 ° C. and 230 ° C. was kept at a constant temperature of 250 ° C. and 150 ° C., respectively, and the dimensional change rate of the inner diameter was measured. The holding time was 2500 hours, and the rate of change in shrinkage was indicated by a negative value. Table 2 shows the test results.

[0034]

[Table 2]

The inner rings of Examples 1 to 6 and Comparative Example 3 have a dimensional change rate of 0.01% or less and exhibit excellent dimensional stability. In Examples 7 and 8 in which the carbonitriding treatment was performed, although the dimensional change rate was slightly larger than these, the standard (0.015
% Or less). Comparative Examples 1 and 2 have a small dimensional change rate, but show a dimensional change in shrinkage in a test of tempering at 350 ° C. and holding at 250 ° C., so that the fitting stress of the inner ring may be excessive. Comparative Example 4, which contains a large amount of Cr and Mo, has a high coefficient of expansion and is out of the standard.

(2) Peeling Test In the peeling test, a ring-shaped test piece having a gentle curvature in a cylindrical portion was attached to a drive shaft and a driven shaft parallel to the drive shaft, and the cylindrical surfaces of both test pieces were pressed together. It rolls by hitting. The dimensions of each test piece were 40 mm in diameter, 12 mm in height, and 60 mm in the sub-curvature radius of the cylindrical portion. The cylindrical surface of the test piece on the drive shaft side was ground to a roughness of Rmax 3 μm, and the cylindrical surface of the test piece on the driven shaft side. Is mirror-finished. The peeling strength is evaluated by the peeling area ratio of the cylindrical surface of the driven shaft side test piece at the end of the test. A peeling test was performed on Examples 1 and 7 and Comparative Examples 1 and 3 under the following test conditions. Note that the same type of sample was used as a pair for both the test piece on the drive shaft side and the test piece on the driven shaft side.

The maximum surface roughness of the test piece: 3.0 μm (on the drive shaft side),
0.2 μm (driven shaft side) ・ Contact surface pressure Pmax: 2.3 GPa ・ Lubricant oil: Turbine oil VG46 ・ Drive shaft rotation speed: 2000 rpm ・ Total rotation speed: 4.8 × 10 ⁵ times

[0038]

[Table 3]

Table 3 shows the test results. Each of the test pieces of the examples had a peeling occurrence area ratio of about 1%,
Shows excellent peeling strength. Each test piece of the comparative example has a large peeling generation area ratio that is three times or more that of the example.

(3) Smearing test In the smearing test, two ring-shaped test pieces having the same shape as the peeling test are similarly rolled using the same apparatus as the peeling test. In this test, the driven shaft is driven to rotate at a constant speed, and the driving shaft is gradually increased in speed from the driven shaft at a constant speed. The cylindrical surface of the driven shaft side test piece has the same surface roughness Rmax as the drive shaft side test piece.
The difference is that it is finished to 3 μm. The smearing strength is evaluated based on the speed ratio between the drive shaft and the driven shaft when smearing occurs on the cylindrical surface of the test piece. A smearing test was performed on Examples 1 and 7 and Comparative Examples 1, 3, and 5 under the following test conditions. In this test, the specimens of the sliding pair were of the same kind.

· Maximum surface roughness of the test piece: 3.0 µm · Contact surface pressure Pmax: 2.1 GPa · Lubricating oil: Turbine oil VG46 · Drive shaft rotation speed: Increase from 200 rpm by 100 rpm · Driven shaft rotation speed: 200 rpm Table 3 also shows the results of the fixed test. In the test pieces of the examples, smearing does not occur up to a large speed ratio of 1.4 times or more as compared with the comparative example 1. In each test piece of the comparative example, smearing occurred at a speed difference of about half of that of the example.

(4) Rolling Fatigue Test In the rolling fatigue test, a roller is press-fitted into the inner surface of a ring-shaped test piece assuming an inner ring, and a tensile stress is applied in the circumferential direction of the test piece. A method was used in which the test piece provided with a roller was rolled with a rotating roller, and tests were performed on Examples 1 and 7 and Comparative Examples 1, 3, and 5 under the following test conditions.
In this test, the sample number N was set to 10, and the fatigue strength was set to L.
The evaluation was made based on 10 lifespans (the number of times that 90% of the samples can be used without being damaged).

Test specimen dimensions: outer diameter 20 mm, inner diameter 14 mm, length 20 mm Fitting stress: 425 MPa (tensile stress on the test piece rolling surface) Mating roller dimensions: diameter 12 mm, length 12 mm, sub-curvature Radius 480 mm Contact stress Pmax: 3.0 GPa Load speed: 6120 operations / minute The test results are shown in Table 3. Comparative example is high temperature 300 ℃
Although the life was significantly shortened by tempering at 350 ° C., Example 1 tempered at a higher temperature of 350 ° C., and Comparative Examples 1 and 3 tempered at a low temperature of 180 ° C. and Comparative Example 5 tempered at a low temperature at a carbonitriding treatment Longer lifespan than. Example 7 in which the carbonitriding treatment is performed has a longer life.

From the results of the above tests, those of Examples are as follows.
It can be seen that peeling and smearing are unlikely to occur, exhibit excellent rolling fatigue characteristics even under high fitting stress, and have little aging change in dimensions during use.

[0045]

As described above, the roll supporting apparatus for a paper machine according to the present invention provides a double row roller bearing for supporting at least a race of a double row roller bearing by adding 0.3% by mass of Si as an alloy element.
% Or more and 3.0% or less, Ni is 0.1% or more and 3.0% or less, V is 0.05% or more and 1.0% or less, and Mo is 0.05% or more and 0% or more. Made of steel containing less than 25%, alone or in combination, with a surface hardness of at least Rockwell hardness HRC 58, so that the bearing material and surface hardness after quenching and tempering are stable even at high temperatures. As a result, it is possible to obtain excellent rolling fatigue characteristics and surface damage resistance, extend the durable life of the roll supporting device used in a high-temperature environment, and prolong the maintenance cycle of the paper machine.

The rolling contact characteristics can be improved by adding Mn of 0.2% or more and 1.5% or less and Cr of 0.3% or more and 5.0% or less by mass% as an alloying element. Surface toughness can be further improved, and a carbonitrided layer is formed on at least the surface layer of the bearing ring of the bearing, and the amount of residual austenite of the carbonitrided layer is set to 10% by volume or more, so that the surface layer has high toughness. , The generation and propagation of cracks can be suppressed, and the durability life of the roll support device can be further extended.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of a dryer roll in which a roll supporting device according to an embodiment is incorporated.

FIG. 2 is an enlarged longitudinal sectional view showing a bearing portion of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roll body part 2 End plate 3, 4 Roll neck part 5 Self-aligning roller bearing 6 Steam introduction pipe 7 hole 8 Pumping car 9 Drainage pipe 10 Track 11 Inner ring 12 Track 13 Outer ring 14 Roller 15 Cage 16 Housing 17 Taper sleeve 18 Nut

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yukihisa Tsumori 3066 Oyumida, O-Fuji, Kuwana-shi, Mie F-term in NTN Corporation (reference) 3J101 AA15 AA25 AA43 AA54 AA62 BA53 BA56 BA70 DA02 DA03 EA02 FA06 FA31 GA60 4L055 CF01 CG14 EA25 EA27 EA29 FA30

Claims (6)

[Claims] 1. A roll supporting device for a paper machine in which a roll is rotatably supported on a housing by a double row roller bearing, wherein at least the race of the bearing is at least 0.3% by mass as an alloy element and at least 0.3% by mass. 3.0% or less, Ni is 0.1% or more and 3.0% or less, and V is 0.05% or less.
% And 1.0% or less, Mo is 0.05% or more and 0.2% or less.
Made of steel containing less than 5% alone or in combination,
A roll supporting device for a paper machine, wherein the surface hardness is at least Rockwell hardness HRC58. 2. The steel material has a mass% as an alloying element,
2. The roll supporting device for a paper machine according to claim 1, wherein Mn is added at 0.2% or more and 1.5% or less, and Cr is added at 0.3% or more and 5.0% or less. 3. The roll supporting apparatus for a paper machine according to claim 1, wherein a carbonitrided layer is formed on at least the surface of the bearing ring of the bearing, and the amount of retained austenite of the carbonitrided layer is 10% by volume or more. . 4. The roll supporting device for a paper machine according to claim 1, wherein said roll is a dryer roll. 5. The roll supporting device for a paper machine according to claim 1, wherein an inner ring of the double row roller bearing is fitted to a neck portion of the roll with a tapered hole. 6. The roll supporting device for a paper machine according to claim 1, wherein said double row roller bearing is a self-aligning roller bearing.