JP2003113840A - Ball bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball bearing which suppresses generation of any smearing attributable to the slip on a raceway surface of inner and outer rings, reduces heat generation of the bearing caused by the slip, and suppresses any temperature fluctuation. SOLUTION: In this ball bearing, the sectional height is set to be 20-25% of the inside diameter, the width is set to be 150-160% of the sectional height, the ball diameter is set to be 45-49% of the sectional height, the radius of curvature of a race groove of the inner and outer rings is set to be 53-55% of the ball diameter, and a chemical conversion coating is performed on the raceway surface of the inner and outer rings, or the coating is squeezed by applying the pressure to the surface of the coating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an expander roll that is arranged in a wire part, a press part, or the like of a papermaking machine to extend wrinkles of paper, a twisting wire machine that manufactures a wire, etc. The present invention relates to a ball bearing suitable for use under a light load or in a state where the inner ring and the outer ring have a relative inclination.

[0002]

2. Description of the Related Art As shown in FIG. 5, a general expander roll 100 has a curved roll, and a single curved roll shaft 101 has dozens of bearings (ball bearings) 110. It is installed at intervals. The inner ring of the ball bearing 110 is mounted so as to fit loosely on the roll shaft 101, and the outer ring of the ball bearing 110 is mounted on the bearing case 10.
It is mounted on a cylindrical bobbin 103 that forms a roll through the two. The bobbins 103 are connected to each other by a sleeve 104 and an O-ring 105 mounted on the outer diameter surface of the sleeve 104. The O-ring 105 needs to have sufficient flexibility so that the axial gap between the end faces of the adjacent bobbins 103 can be changed during one rotation of the bobbins 103.

On the other hand, when the O-ring 105 does not have sufficient flexibility, the balls of the ball bearing 110 move axially within the raceways of the inner and outer rings. In this case, the contact angle of the ball bearing 110 fluctuates between plus and minus during one rotation of the bobbin 103.

An example of a conventional ball bearing used in such an expander roll 100 is shown in FIGS. 6 and 7. The ball bearing 20 of FIG. 6 includes an outer ring 21, an inner ring 22, a plurality of rolling elements (balls) 23 inserted between the outer ring 21 and the inner ring 22, and a retainer 24 that rotatably holds the balls 23.
And a seal member 25 for blocking the bearing space from the outside. The seal member 25 has one end fixed to a recess formed in the inner diameter surface of the outer ring 21 along the circumferential direction, and the other end facing the recess of the outer ring 21 on the outer diameter surface of the inner ring 22. It is provided so as to be in sliding contact with the concave portion formed in. Further, the cross-section height (dimension in the radial direction from the inner ring inner diameter surface to the outer ring outer diameter surface) H is 35 to 40% of the inner diameter d, and the width B is 90 to 10 of the cross-section height H.
0% (here, 93%), the ball diameter Da is 50 to 60% (here, 60%) of the sectional height H, and the radius of curvature (ri, ri, of the inner ring raceway groove and the outer ring raceway groove). re)
Is 51 to 52% of the ball diameter Da (here, 51.7%, respectively).
It was set to 5%. ). No special treatment such as coating is applied to the inner and outer ring raceways. In the example shown in FIG. 6, under the above high-speed and light-load use conditions,
Due to heat generation due to slippage on the contact surface with the ball 23, fine seizure damage on the rolling surface of the ball and the inner ring / outer ring raceway surface, which is called smearing on the inner ring / outer ring track, was likely to occur.

On the other hand, the ball bearing 30 shown in FIG. 7 has specifications that take measures against smearing that occurs in the ball bearing 20 shown in FIG. In the ball bearing 30, the ball diameter Da is set to 45% to 49% of the sectional height H, and the radius of curvature (r
i, re) is 53 to 55% (here, 53%) of the ball diameter Da, and the inner ring / outer ring raceways are coated with a chemical conversion treatment film (here, a manganese phosphate salt is coated). There is. The other basic configurations such as the cage 34 and the seal member 35 are the same as those of the ball bearing 20 shown in FIG.

[0006]

The ball bearing used in the expander roll described above has a relatively high speed outer ring rotation such that the dmN exceeds 350,000, and the bearing load is limited to the bearing case and the bobbin's own weight. Used under extremely light weight conditions. Under such conditions, even in the example shown in FIG. 7, smearing may occur on the inner ring / outer ring raceways due to heat generation due to slippage on the contact surface with the balls 33. When smearing occurs on the inner ring / outer ring raceways, the noise and vibration associated with rotation increase, which affects products using such ball bearings, making them unusable. Further, in the expander roll 100, a plurality of O-rings 105 (eg, three O-rings 105) are provided on the outer diameter surface of the sleeve 104 that connects the bobbins 103 to each other in order to improve the sealing performance so that moisture does not enter the inside of the bearing case 102. Above) may be provided. In this case, the crushing margin of the O-ring 105 between the inner diameter surface of the bobbin 103 and the outer diameter surface of the sleeve 104 becomes large, and the axial gap between the end surfaces of the adjacent bobbin 103 during one rotation of the bobbin 103. Ball bearing 11
It was easy to fall into the state where the balls moved in the axial direction within the 0 inner ring / outer ring raceway surface (the state where the contact angle of the ball bearing 110 swings to plus or minus). In such a state, smearing may occur. Therefore, the conventional ball bearing has been required to be improved to suppress the occurrence of smearing.

The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress the occurrence of smearing due to slippage on the inner ring / outer ring raceways and to prevent the bearing from sliding. An object of the present invention is to provide a ball bearing capable of reducing heat generation and suppressing temperature fluctuation of the bearing.

[0008]

The inventors of the present invention have reduced the power loss by preventing the deterioration of the lubricant and the rupture of the oil film to reduce the dynamic torque of the ball bearing, thereby reducing the heat generation of the ball bearing and the temperature fluctuation. We paid attention to the fact that it is effective in suppressing the occurrence of smearing. Then, under the conditions of relatively high rotation and light load, the inventors should appropriately set the lubricity of the bearing internal grease, the contact state between the inner ring / outer ring raceway surface and the balls, and the coating strength (difficulty of removal). so,
It has been found that the slip on the raceways of the inner and outer rings can be reduced to suppress the temperature rise of the bearing and the occurrence of smearing due to the slip. The above object of the present invention is a ball bearing used for grease lubrication, in which balls are held between an inner ring and an outer ring via a cage, and the cross-sectional height is 20 to 25 with an inner diameter.
%, The width is 150 to 160% of the sectional height, the ball diameter is 45 to 49% of the sectional height, the radius of curvature of the inner ring and the outer ring raceway groove is 53 to 55% of the ball diameter, and the inner ring and the outer ring This is achieved by a ball bearing characterized in that the coating is crushed by applying a chemical conversion coating to the raceway surface or applying pressure to the coating surface.

According to the present invention, since the ratio of the sectional height to the inner diameter, the ratio of the width to the sectional height, and the ball diameter are appropriately set, the internal space of the bearing is wide and the space other than the space where the balls revolve is revolved. A wide space can be secured, and the grease can be kept stationary without being moved by the balls or the cage. Therefore, the heat generated by stirring the grease is reduced, the bearing temperature can be lowered, and the temperature fluctuation can be reduced. Also, the bearing P
Since the CD (pitch circle diameter) can be reduced, heat generation of the bearing is reduced. Since the decrease in the viscosity of the grease base oil is reduced, the oil film thickness can be maintained, the breakage is less likely to occur, and smearing is less likely to occur.

Further, according to the present invention, since the radius of curvature of the raceway groove of the inner ring and the outer ring is 53% to 55% of the ball diameter, the contact ellipse area between the ball and the raceway surface of the inner ring / outer ring becomes small, which causes contact. Spin friction is reduced and heat generation can be reduced. As a result, since the decrease in viscosity of the grease base oil is small, it is possible to maintain the oil film thickness, make it difficult to break, and prevent smearing. Further, since the centering property of the bearing is improved by increasing the radius of curvature of the inner ring / outer ring raceway groove, the bearing can obtain the same effect even with respect to the inclination of the inner ring / outer ring.

Further, according to the present invention, since the raceways of the inner and outer rings are coated or crushed by applying pressure to the coating surfaces, even if the grease film is broken, the raceway between the inner and outer races and the balls are Since it is difficult for the contact portion to make metal contact, smearing can be suppressed. In addition, since the coating is rolled by applying pressure to the coating surface and crushing it, it becomes thin and difficult to remove, and it becomes more difficult to make metal contact, and the removed coating particles mix in grease and cause acoustic deterioration of the bearing. In most cases, the coated particles that have been removed do not deteriorate the grease. Sealing members may be provided at both axial ends of the ball bearing. At this time, the grease in the bearing space can be efficiently stirred.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. FIG. 1 shows an embodiment of a sealed ball bearing according to the present invention. The ball bearing 10 according to the present embodiment includes an outer ring 11, an inner ring 12, balls 13 inserted between the outer ring 11 and the inner ring 12, a cage 14 that holds the balls 13 at regular intervals in the circumferential direction, and a seal member 15. It is composed of. Cage 1
4 and the seal member 15 correspond to the ball bearings 20 and 3 shown in FIGS.
Its structure and operation are the same as those of No. 0. As a specification of the ball bearing 10, the sectional height H is 20% to 25% of the bearing inner diameter d.
The width B is 150% to 160% of the sectional height H, and the ball diameter Da is 45% to 50% of the sectional height H.

According to the above-mentioned specifications, since the ball bearing 10 has a large internal space and a space other than the space around which the balls 13 revolve, the grease is not moved by the balls 13 and the cage 14 and settles in that space. To be Therefore, heat generated by stirring the grease is reduced, so that the bearing temperature can be lowered and the temperature fluctuation can be reduced. Further, since the PCD of the bearing is reduced, heat generation of the bearing is reduced, and the viscosity of the grease base oil is less likely to be reduced, so that the oil film thickness can be maintained and the fracture is less likely to occur. Therefore, smearing is less likely to occur at the contact portion between the inner ring / outer ring raceway groove and the ball.

The radius of curvature (ri, re) of the inner ring / outer ring raceways of the ball bearing 10 is 53% to 55% (ri, r) of the ball diameter Da.
Since e = 0.53 to 0.55 Da), the contact ellipse between the balls and the inner ring / outer ring raceway surface (the size of the running trace generated at the contact portion with the rolling element) becomes smaller, and the spin friction caused by the contact is reduced. It becomes smaller and heat generation can be reduced. For this reason, the decrease in the viscosity of the grease base oil is reduced, the oil film thickness can be maintained, the breakage is less likely to occur, and smearing is less likely to occur.

Inner ring 11 of ball bearing 10 according to the present embodiment
Further, the raceway surface of the outer ring 12 is coated with a chemical conversion coating. Therefore, even if the grease film breaks, the inner ring /
Smearing is less likely to occur because the metal contact does not occur between the outer ring raceway surface and the balls. Further, when pressure is applied to the chemical conversion coating to crush it, the coating becomes difficult to remove and metal contact becomes difficult. At the same time, it is possible to prevent the taken-off coating particles from being mixed in the grease, so that it is possible to prevent acoustic deterioration of the bearing and also prevent deterioration of the grease.

As the chemical conversion coating, a manganese phosphate-based coating having good abrasion resistance is usually used, but other coating such as zinc phosphate-based coating may be used. As a method of applying pressure to the coating to crush it, there is a method of incorporating a plurality of balls into the coated inner and outer rings and rotating the inner or outer ring while applying an axial load. At this time, the axial load may extend in both the forward and reverse directions to widen the range in which the coating is crushed. Furthermore, there is also a method in which a rotating pressing jig is pressed against the rotating inner or outer raceway groove to apply pressure to the coating to crush it. The outer diameter of the pressing jig is set so that the curvature becomes the same as the curvature of the ball in the cross section in one direction.

Next, for the purpose of clarifying the action and effect of the ball bearing 10, a comparative experiment between the ball bearing 10 according to this embodiment and the ball bearings 20 and 30 of the conventional specifications will be conducted. The outer diameter, inner diameter, width, and other dimensions of each ball bearing are the same as described above. The detailed specifications of each ball bearing are shown in Table 1 below.

[0018]

[Table 1]

In this experiment, the test apparatus 1 shown in FIG.
20 is used. The test apparatus 120 is rotatably supported at both ends, and has a curved roll shaft 121, and a bearing portion P provided on the shaft at a predetermined interval. In the bearing part,
The ball bearings 10, 20 and 30 described above can be arranged according to the test. Other configurations are shown in FIG.
It is the same as the expander roll shown in.

In this test, the ball bearings 10 and 2 were rotated at different rotational speeds for a predetermined time at each rotational speed.
Examine each of the 0 and 30 temperature variations. As a test method, the rotation speed is increased to the maximum speed condition of the ball bearing, and the bearing temperature with respect to the rotation speed is measured twice for each ball bearing. Based on the results of this test, FIG. 3 shows a graph comparing the inner ring temperature with respect to each rotation speed. In this figure, the first measured value of each ball bearing (simply a bearing in the figure) and the second measured value are marked with a symbol. According to this figure, the ball bearing 2
The result of 0 is that the bearing temperature of the second time is almost the same as the bearing temperature of the first time. In the ball bearing 20, the second bearing temperature was not lower than the first measured value. The reason is that the grease was not stably held in the bearing space at the first measurement for each ball bearing. Means Further, with the ball bearing 30, although the measured value of the second bearing temperature was slightly lower than that of the first bearing temperature, it was not sufficient. On the other hand, for the ball bearing 10 according to the present invention, at the time of the second measurement, the measured value at each rotation speed was significantly lower than the first temperature of the bearing. Therefore, in the ball bearing 10, it was found that the grease was stably held in the bearing space during the first measurement.

Next, in order to measure and compare the temperature fluctuations of the ball bearings 10 and 30 when the ball bearings 10 and 30 were rotated at a predetermined rotation speed for a long time, the following tests were conducted. Rotation speed 2
The inner ring temperature (T i) of each ball bearing when measured at 000 rpm and rotated for 250 hours is measured. FIG. 4 is a graph showing the test time and the inner ring temperature with respect to the elapsed time, based on the results of this test. In this figure, the horizontal axis represents the test time (h) and the vertical axis represents the inner ring temperature (Ti) with respect to the test time (h). According to this figure, the temperature of the ball bearing 30 fluctuates in the range of 65 ° C. to 102 ° C. from the start of the test to the elapse of a predetermined time.
On the other hand, in the ball bearing 10 according to the present embodiment, from 30 ° C. to 5 ° C. from the start of the test to the elapse of a predetermined time.
The temperature fluctuates in the range of 0 ° C. Therefore, when the ball bearing 10 is rotated at a predetermined rotation speed for a long time, the temperature fluctuation of the ball bearing 10 is
It was found that it was significantly smaller than the ball bearing 30.

Based on the specifications of each ball bearing and the above two test results, the inventors have made clear the following points. (1) When the ratio of the ball diameter to the sectional height is small and the ratio of the radius of curvature of the inner ring / outer ring raceway groove to the ball diameter is large, the bearing temperature is low and the temperature fluctuation can be small. (2) In addition to (1), the bearing temperature is lower and the temperature fluctuation can be reduced when the ratio of the sectional height to the inner diameter is small and the ratio of the width to the sectional height is large. From these points, by setting the specifications of the ball bearing as shown in the ball bearing 10 of Table 1, the slip of the ball on the inner ring / outer ring raceway surface can be reduced under the conditions of relatively high rotation and light load of the outer ring. it can. Therefore, according to the ball bearing having such specifications, smearing due to slippage can be significantly suppressed, and it has been found that the temperature fluctuation of the bearing can be reduced.

The present invention is not limited to the above-described embodiment, but can be appropriately modified and improved. The seal member of the ball bearing is not limited to a so-called contact type in which both ends are fixed or slidably contact with the outer ring and the inner ring, respectively.
For example, a so-called non-contact type seal member in which a gap is provided between the end portion of the seal member and the inner diameter surface of the inner ring may be used. However, from the viewpoint of suppressing fluctuations in bearing temperature and occurrence of smearing, it is preferable to use a contact-type seal member that can efficiently stir grease in the bearing space.

[0024]

EFFECTS OF THE INVENTION According to the present invention, the lubricity of the grease inside the bearing and the inner ring
Contact state between outer ring raceway surface and balls and coating strength (difficulty in removing)
By appropriately setting, it is possible to suppress the occurrence of smearing due to slippage on the inner ring / outer ring raceway surface, reduce the heat generation of the bearing due to slippage, and suppress the temperature fluctuation. Can be provided.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a ball bearing of the present invention.

FIG. 2 is a schematic structural diagram showing a test apparatus used for a comparative test.

FIG. 3 is a graph showing a comparison of the inner ring temperature with respect to the rotation speed of the ball bearing of the present invention and the ball bearing of the conventional specification.

FIG. 4 is a graph showing a comparison of inner ring temperature fluctuations between the ball bearing of the present invention and a conventional ball bearing.

FIG. 5 is a schematic structural diagram of an expander roll.

FIG. 6 is a vertical sectional view showing a conventional ball bearing.

FIG. 7 is a vertical sectional view showing another conventional ball bearing.

[Explanation of symbols]

10 ball bearings 11 outer ring 12 inner ring 13 Rolling elements (balls) 14 cage 15 Seal member 100 expander roll 101 roll axis 102 bearing cover 103 bobbin 104 sleeve 105 O-ring 110 bearings (ball bearings) 120 test equipment

Continued front page    F term (reference) 3J101 AA03 AA32 AA42 AA52 AA62                       BA02 BA53 BA54 BA55 CA13                       DA05 FA01 FA32 FA33 FA60                       GA60

Claims (2)

[Claims] 1. A ball bearing used for grease lubrication, in which balls are held by a cage between an inner ring and an outer ring, the cross-sectional height being 20 to 25% of the inner diameter of the bearing, and the width being the cross-sectional height. 150-160% of the ball diameter and 45-49% of the cross-sectional height
And the radius of curvature of the inner ring raceway groove and the outer ring raceway groove is 5
A ball bearing characterized in that the content thereof is 3 to 55%, and that the raceway surfaces of the inner ring and the outer ring are provided with a chemical conversion treatment coating, or the coating is crushed by applying pressure to the coating surface. 2. The ball bearing according to claim 1, wherein seal members are provided at both ends in the axial direction.