JP7176539B2 - How to select a rolling bearing - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of selecting a rolling bearing for use in steel manufacturing equipment, and more particularly to a method of selecting a rolling bearing that provides a more appropriate radial clearance for the rolling bearing.

A rolling bearing is one of the most important parts among the many parts that make up a machine. In addition, in recent years, in steel manufacturing facilities, demands for high load, high speed, long life, etc. have been increasing. Therefore, selection of the optimum rolling bearing is important from an environmental point of view, such as energy saving, because it leads not only to longer bearing life but also to reduced friction.
One factor in bearing selection is the bearing clearance (radial clearance). It is known that if the rolling bearing has a small clearance during operation, the number of rollers supporting the load increases and the fatigue life increases. However, as the amount of negative clearance increases, the fatigue life decreases significantly. Therefore, in general, the bearing clearance (initial bearing internal clearance) is set to a clearance that is slightly larger than zero during operation (dynamic clearance). Bearings are selected as follows (see Non-Patent Document 1).

Here, there are two factors in reducing the clearance: the reduction due to the fitting (interference) between the bearing and the shaft or the housing, and the reduction due to the temperature difference between the inner and outer rings during operation. The amount of clearance reduction due to fitting with the shaft or housing can be derived from the amount of fitting and the Young's modulus of the material, so it can be calculated quantitatively.
On the other hand, regarding the temperature difference between the inner and outer rings during operation, conventionally, it was assumed that the temperature difference between the inner ring temperature and the outer ring temperature of the bearing under normal operating conditions was about 5 to 10°C. selection of bearing clearance. Further, the inner ring temperature and the outer ring temperature are assumed to be constant in the circumferential direction.
In addition, since the clearance of the bearing has a great influence on the service life of the bearing, conventionally, by using a material with a small coefficient of thermal expansion for the inner ring of the bearing, the change in the raceway diameter of the inner and outer rings due to the temperature difference between the inner and outer rings is minimized. is also proposed to be reduced (see Patent Document 1).

Rolling bearings for industrial machinery・No. 1103 2016 AX-3, NSK Ltd., January 2016, p A174-175, p A69

Japanese Patent Application No. 2010-216816

However, the temperature difference between the inner and outer rings is affected by the lubricating oil actually used for the bearing, the ambient temperature (usage atmosphere), etc., so it is very difficult to predict the temperature difference.
In particular, with the above conventional method, in the case of bearings operated at high speed and high load, the amount of clearance reduction tends to be greater than the expected temperature difference between the inner and outer rings of the bearing, resulting in an excessively small clearance and internal preload. It was found that there was a problem that the clearance was too small, leading to breakage. Rolling bearings are used at high speeds and under high loads in steel manufacturing equipment, so the impact is great.
Also, if the clearance is selected based on the idea that the temperature difference is constant in the circumferential direction, the temperature tends to rise in the direction of the load when the load applied to the bearing increases. In this case, in order to select the optimum bearing clearance, it is necessary to accurately grasp the temperature distribution of the bearing and calculate the amount of thermal expansion of each of the inner and outer rings of the bearing.
SUMMARY OF THE INVENTION It is an object of the present invention to make it possible to select a more optimal rolling bearing with a more optimal radial clearance amount.

In order to solve the problem, one aspect of the present invention is a method for selecting a rolling bearing to be used in steel manufacturing equipment, wherein the rolling bearing is installed at a target location during operation of the steel manufacturing equipment in which the target rolling bearing is used. The temperature of the inner and outer rings of the existing rolling bearing is measured, and based on the temperature difference between the inner and outer rings of the existing rolling bearing measured above, the thermal expansion of the inner and outer ring raceway diameters of the selected rolling bearing Estimate the temperature difference reduction amount, which is the reduction amount of the internal clearance caused by the difference in the amount, and use the estimated temperature difference reduction amount to determine the bearing internal clearance of the rolling bearing to be selected when selecting the rolling bearing. The gist is to do.
As the temperature difference used when estimating the amount of decrease in temperature difference, it is preferable to employ the value of the largest temperature difference among the temperature differences between the inner and outer rings along the circumferential direction.

According to the aspect of the present invention, it is possible to more accurately estimate the decrease in the clearance due to the temperature difference between the inner and outer rings during operation. As a result, according to the aspect of the present invention, it is possible to select a rolling bearing having a more accurate bearing clearance, which contributes to improving the accuracy of operation of steel manufacturing equipment.

1 is a diagram illustrating an example of a target steel manufacturing facility according to an embodiment of the present invention; FIG. It is a figure explaining the processing example of the selection method of the bearing which concerns on embodiment based on this invention. It is a figure explaining the temperature measurement of the inner-outer ring|wheel which concerns on embodiment based on this invention. It is a figure which shows the example of the temperature measurement position by the side of an outer ring which concerns on embodiment based on this invention. It is a figure explaining the example of the temperature of the inner ring|wheel and the outer ring|wheel which were measured.

Next, embodiments of the present invention will be described with reference to the drawings.
In this embodiment, an annealing line as shown in FIG. 1 is taken as an example of the target steel manufacturing equipment, and the bearing of the bridle of the tension leveler 1 (shape straightening machine) involved in the transportation of the steel plate in the line is selected. set to target. This embodiment is suitable for rolling bearings used in high-load, high-speed rotation environments in steel manufacturing facilities.
In this embodiment, the outer ring is a fixed ring and the inner ring is a rolling wheel. Also, the rolling bearing of the present embodiment is a roller bearing. Further, in this embodiment, it is assumed that a load is applied to the bearing in the vertical direction.

(Constitution)
As shown in FIG. 2, the rolling bearing selection method of the present embodiment includes an existing temperature measurement step 2, a temperature difference decrease amount estimation step 3, and an internal clearance determination step 4.
<Existing temperature measurement process 2>
In the existing temperature measurement step 2, the temperature of the inner ring and outer ring of the existing rolling bearing installed at the location to be selected is measured while the steel manufacturing facility in which the target rolling bearing is used is in operation.
For the measurement of temperature, the value when the equipment is in steady operation is adopted. Moreover, it measured several times and used the average value.
As shown in FIG. 3, the existing temperature measurement process 2 of this embodiment comprises an inner ring temperature measurement sensor 13 that measures the temperature of the inner ring 10A of the rolling bearing 10, and an outer ring temperature measurement sensor 14 that measures the temperature of the outer ring 10B. and

The inner ring-side temperature measurement sensor 13 is arranged between the inner peripheral surface of the inner ring and the outer peripheral surface of the shaft, as shown in FIG. 3, for example. In this embodiment, as shown in FIG. 3, the inner ring side temperature measurement sensors 13 are arranged at two positions, namely, an upper position and a lower position along the direction of load application. A signal cable of each sensor 13 is electrically connected to a wireless transmitter 15 . The inner ring side temperature measurement sensor 13 may be configured to indirectly measure the temperature of the inner ring 10A. For example, the inner ring side temperature measurement sensor 13 may measure the temperature at a position near the inner ring 10A of the shaft 11 to which the inner ring 10A is connected, and calculate the temperature of the inner ring 10A from the measured temperature based on heat transfer theory.

The outer ring side temperature measurement sensor 14 is provided between the outer peripheral surface of the outer ring 10B and the housing 12 as shown in FIG. 3, for example. As shown in FIG. 4 , a plurality of outer ring-side temperature measurement sensors 14 are arranged along the circumferential direction of outer ring 10B, and the cable of each sensor is electrically connected to wireless transmitter 15 .
The wireless transmitter 15 is configured by, for example, a wireless LAN, and transmits the input measured temperature signal.

Although FIG. 3 illustrates a case where two wireless transmitters 15 are used, the number of wireless transmitters 15 may be one or three or more depending on the layout of various devices.
In addition, the existing temperature measurement process 2 has a temperature difference calculator 16 .
The temperature difference calculation unit 16 inputs temperature signals measured by the inner ring side temperature measurement sensor 13 and the outer ring side temperature measurement sensor 14 via the wireless transmission device 15 . The temperature difference calculator 16 takes the average value of the temperature signals measured by the two inner ring side temperature measurement sensors 13 as the temperature of the inner ring 10A. Here, on the side of the inner ring 10A, which is a rotating ring, each temperature along the circumferential direction is the same temperature.

The temperature difference calculation unit 16 obtains the temperature distribution of the temperature difference between the inner and outer rings along the circumferential direction based on the temperature measurement values at a plurality of points along the circumferential direction of the outer ring 10B, which is the stationary ring (see FIG. 5). ), the largest temperature difference between the inner and outer rings is calculated. In this embodiment, the temperature distribution of the outer ring 10B along the circumferential direction based on the temperature measurement values at a plurality of points along the circumference of the outer ring 10B, which is the fixed ring, is calculated. The lowest temperature X is obtained, and the lowest temperature X is subtracted from the temperature measurement value of the inner ring 10A to obtain the temperature difference ΔT between the inner and outer rings to be employed. As the temperature difference ΔT between the inner and outer rings to be adopted, the temperature at the outer ring position within a range of ±5 degrees in the circumferential direction around the position of the lowest temperature X may be adopted.

The temperature difference between the inner and outer rings is measured on the non-loaded side (lowest position in this embodiment) opposite to the load input position (upper in this embodiment). It may be regarded as a value with a large temperature difference between the rings. However, if the temperature distribution is obtained and determined from the obtained temperature distribution, the largest temperature difference value among the temperature differences between the inner and outer rings can be obtained more reliably.

<Temperature difference decrease amount estimation step 3>
In the temperature difference decrease amount estimation step 3, based on the temperature difference between the inner and outer rings obtained by the temperature difference calculation unit 16, the internal A temperature difference decrease amount δt, which is a clearance decrease amount, is estimated.
The temperature difference decrease amount is calculated, for example, by the following formula.
δt [mm] = α・ΔT・D0
here,
α: Linear expansion coefficient of bearing material ΔT [°C]: Temperature difference between inner ring 10A and outer ring 10B D0 [mm]: Raceway diameter of outer ring 10B.

<Internal clearance determination step 4>
The internal clearance determination step 4 determines the initial bearing internal clearance δ0 in the radial direction of the selected rolling bearing using the temperature difference reduction amount estimated in the temperature difference reduction amount estimation step 3 when selecting the rolling bearing. .
Here, the bearing internal clearance is obtained by, for example, the following formula.
δu = δ0 + δf + δt
here,
δu [mm] : Operating clearance δ0 [mm] : Bearing internal clearance δf [mm] : Decrease in internal clearance due to interference δt [mm] : Decrease in temperature difference.

Here, the reduction amount δf of the internal clearance due to the interference is geometrically calculated.
In the internal clearance determining step 4, the bearing internal clearance δ0 that makes the operating clearance δu a predetermined value is obtained from the above equation.
The operating clearance is normally set to zero or a slightly positive value.
Then, a rolling bearing having the bearing internal clearance obtained in the internal clearance determining step 4 is selected, and the selected bearing is adopted when the next bearing is replaced.

(effect)
This embodiment has the following effects, for example.
(1) This embodiment is a method for selecting a rolling bearing to be used in a steel manufacturing facility, and an existing rolling bearing installed at a target location during operation of the steel manufacturing facility in which the target rolling bearing is used. The temperature of the inner ring 10A and the outer ring 10B of the bearing is measured, and based on the measured temperature difference between the inner ring 10A and the outer ring 10B of the existing rolling bearing, the difference in the amount of thermal expansion between the inner ring raceway diameter and the outer ring raceway diameter of the rolling bearing to be selected. Estimate the amount of reduction in temperature difference, which is the amount of reduction in the internal clearance caused by the temperature difference.
According to this configuration, it is possible to more accurately estimate the decrease in the clearance due to the temperature difference between the inner and outer rings during operation. As a result, it is possible to select a rolling bearing having a more accurate bearing clearance, which contributes to improving the accuracy of operation of steel manufacturing equipment.

(2) In this embodiment, as the temperature difference used when estimating the temperature difference reduction amount, the largest temperature difference value among the temperature differences between the inner and outer rings along the circumferential direction is adopted.
That is, in this embodiment, the temperature distribution in the circumferential direction of the inner ring 10A and the outer ring 10B of the bearing is measured, and the measured temperature distribution is based on the measurement result of the location where the temperature difference between the inner ring 10A and the outer ring 10B is the largest. Select the optimum bearing clearance for In general, when the bearing clearance is eliminated and the bearing raceway surface is pressurized, the service life is significantly reduced compared to when the clearance is excessive (see Non-Patent Document 1).

On the other hand, in the present embodiment, by using the measurement result of the portion where the temperature difference between the inner and outer rings is large, it is possible to increase the clearance to be set and design on the safe side.
That is, according to this configuration, by measuring the temperature distribution in the circumferential direction of the inner ring 10A and the outer ring 10B of the bearing, the effect of the temperature distribution in the circumferential direction can be investigated and the amount of change in the inner and outer ring raceways can be derived. became possible. By setting the initial clearance so that the derived raceway diameter of the inner and outer rings eliminates the clearance during operation, the service life of the bearing can be greatly improved.
By integrating the elongation in the circumferential direction based on the temperature distribution of the temperature difference in the circumferential direction, the amount of gap reduction due to the temperature difference (temperature difference reduction amount) can be obtained from the amount of elongation due to the temperature difference. can be

(3) In the present embodiment, when measuring the temperature of the inner ring 10A and the outer ring 10B of the existing rolling bearing, the temperature of the fixed ring of the inner ring 10A and the outer ring 10B of the existing rolling bearing is measured at a plurality of points in the circumferential direction. is measured, the temperature distribution of the temperature difference between the inner and outer rings along the circumferential direction is determined based on the measurement, and the temperature difference used when estimating the temperature difference reduction amount is determined from the determined temperature distribution.
According to this configuration, it is possible to determine the temperature difference between the inner and outer rings to be adopted based on the environment of the actual installation position.

(4) In the present embodiment, temperature measurement sensors are provided on the inner ring 10A and the outer ring 10B of the existing rolling bearing, and the measurement value signals measured by the temperature measurement sensors are received via wireless communication means. Obtain the temperature of the inner ring 10A and the outer ring 10B of the bearing.
According to this configuration, the temperature information can be obtained remotely.

The bearing of the bridle of the tension leveler (shape corrector) in the annealing line (see Fig. 1) was verified, and the optimum clearance of the bearing (designation number: 24032CAME4S11) was selected.
The conditions for using this existing bearing were that the outer ring 10B was a fixed ring, the inner ring 10A was a rotating ring, and the fit of the shaft 11 was an interference fit of m6, and the fit of the housing 12 was a clearance fit of G7. The rotation speed of the shaft 11 was 840 rpm, and the bearing load was 10000 kgf.
In the target annealing line, when the bearing was used with a CN clearance (initial clearance δ0: 0.110 mm), the usable period was 3 months, which was a very short life.
Therefore, verification was performed using the C3 clearance based on the present invention.

As described above, the decrease in bearing clearance has two elements: decrease δf due to fitting between shaft 11 and housing 12, and decrease δt due to temperature difference between inner and outer rings during operation.
The decrease δf of the clearance due to the fitting of the bearing can be obtained from the surface pressure Pm generated between the shaft 11 and the bearing 10, which are interference-fit, and the magnitude of the surface pressure Pm can be obtained from the following formula. Table 1 summarizes the symbols and numerical values used in the derivation of the surface pressure Pm due to the fitting of the bearing 10 this time.

As a result, the surface pressure Pm generated between the shaft 11 and the bearing 10 was 1.25 kgf/mm ² . The expansion amount of the inner ring raceway diameter due to the surface pressure Pm can be obtained by the following formula.

From the formula, it was found that the inner ring raceway diameter expands by 0.058 mm.
Next, we measured the effect of temperature on the bearing clearance.
Based on this embodiment, the effect of the load and the number of rotations on the temperature distribution along the circumferential direction of the bearing 10 was measured. The measurement results are shown in FIG.
The clearance was derived from the measurement results in FIG. The size of the clearance S is expressed by the following formula, where De is the raceway diameter of the outer ring 1, Di is the raceway diameter of the inner ring, and Dw is the diameter of the roller 10C.
S = De - Di - 2Dw

Based on this formula, when the temperature of the outer ring 10B, inner ring 10A, and rollers 10C rises, the operating clearance S' after the temperature change can be expressed by the following formula. Here, α is the linear expansion coefficient, Δte is the average temperature rise of the outer ring 10B, Δti is the temperature rise of the inner ring 10A, and Δtw is the temperature rise of the rollers 10C.
S'=De.(1+α..DELTA.te)
−Di (1 +α・Δti) −2Dw (1 +α・Δtw)
Further, the amount of temperature rise is expressed by the following formula, where t0 is the initial temperature.
Δt = ti - t0

Based on the above equation for the amount of temperature rise Δt and the equation for the residual clearance S, the clearance size S′ after the temperature rise is expressed by the following equation.
S′ = S − {α·De (ti −te )
+2α・Dw(tw−ti)−α・S(ti−t0)}
Here, from α≈0 and t0≈0, it can be approximated as α·S(ti −t0) ≈0.

Further, since the diameter Dw of the roller 10C is smaller than the outer ring raceway diameter De and the inner ring raceway diameter Di, ignoring the amount of expansion of the roller 10C, the clearance size S' after the temperature rise can be expressed by the following equation. I can.
It can be expressed as S' = S - α · De (ti - te).
i.e.
δt = S−S′ = α·De (ti − te) = α·De·ΔT.
Thus, the temperature difference decrease amount δt can be derived from the temperature difference between the inner ring temperature ti and the outer ring temperature te of the bearing. At this time, the value at the position with the largest temperature difference in the circumferential direction was adopted.

Calculating the amount of decrease in the clearance based on the results of temperature measurement of the bearing, it was found that the decrease was δt=0.075 mm.
Therefore, δf+δt = 0.133 mm because it is the sum of the raceway diameter due to fitting and the decrease in clearance due to temperature.
It is desirable to select a bearing so that the size of the operating clearance δu is slightly larger than zero (see Non-Patent Document 1). .170 mm) was selected.
When a bearing with a clearance of C3 selected based on the present invention was used in actual operation, it became possible to use it continuously for 12 months or longer.

2 Existing temperature measurement process 3 Temperature difference decrease amount estimation process 4 Internal clearance determination process 10 Bearing 10A Inner ring 10B Outer ring 11 Shaft 12 Housing 13 Inner ring side temperature measurement sensor 14 Outer ring side temperature measurement sensor 15 Wireless transmitter 16 Temperature difference calculator δt Temperature Decrease amount

Claims (3)

A method for selecting a rolling bearing for use in steel manufacturing equipment, comprising:
Measuring the temperature of the inner ring and outer ring of the existing rolling bearing installed at the target location during operation of the steel manufacturing facility where the target rolling bearing is used,
Amount of reduction in internal clearance caused by the difference in thermal expansion between the inner ring raceway diameter and the outer ring raceway diameter of the selected rolling bearing based on the temperature difference between the inner ring temperature and the outer ring temperature of the existing rolling bearing measured above. , estimating the amount of temperature difference decrease,
When selecting a rolling bearing, the bearing internal clearance of the rolling bearing to be selected is determined using the temperature difference reduction estimated above ,
As the temperature difference used when estimating the temperature difference reduction amount, the largest temperature difference value among the temperature differences between the inner and outer rings along the circumferential direction is adopted.
A method for selecting a rolling bearing characterized by: When measuring the temperature of the inner ring and the outer ring of the existing rolling bearing, the temperature of the fixed ring of the inner ring and the outer ring of the existing rolling bearing is measured at a plurality of points in the circumferential direction, and based on the measurement, Find the temperature distribution of the temperature difference between the inner and outer rings along the circumferential direction,
2. The method of selecting a rolling bearing according to claim 1, wherein the largest temperature difference used when estimating the temperature difference decrease amount is determined from the determined temperature distribution. It has a temperature measurement sensor that measures the temperature of the inner ring and the outer ring of the existing rolling bearing, and by receiving the measurement value signal measured by the temperature measurement sensor via a wireless communication means, the existing rolling bearing 3. The method of selecting a rolling bearing according to claim 1, wherein temperatures of the inner ring and the outer ring are obtained.

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