JP4334184B2 - Cylindrical roller bearing and shaft assembly and design method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention is used in the spindle or the like of a machine tool, relates a bearing bore in the assembly and the design how the cylindrical roller bearing and the axis of the tapered surface.
[0002]
[Prior art]
Some spindles of machine tools that require high speed and high accuracy in bearings use rolling bearings having an inner ring inner diameter surface as a tapered surface. In such applications, if the radial clearance of the bearing is excessive, problems such as deterioration of the spindle accuracy may occur, and if the radial clearance is excessively small, problems such as abnormal heat generation and early peeling of the bearing may occur. The radial clearance adjustment is important. For this reason, the radial gap can be adjusted by expanding the inner ring fitted to the shaft by the action of the tapered surface and adjusting the amount of expansion with the depth of press-fitting in the axial direction.
[0003]
FIG. 4 shows an example of this type of conventional bearing. The double row bearing 1 is a cylindrical roller bearing with an inner ring collar, and has two rows of raceway surfaces 2a, 2b, 3a, 3b arranged in the axial direction on the inner ring 2 and the outer ring 3. The raceways 3a and 3b of the outer ring 3 are formed in a continuous cylindrical surface. The rolling elements 4a and 4b in each row are held by a cage (not shown). An inner diameter surface 2 c of the inner ring 2 is a tapered surface and is fitted to the outer periphery of the tapered portion 6 a of the shaft 6. The radial internal clearance δ of the bearing can be adjusted by press-fitting the shaft 6 using the tapered surface and expanding the inner ring 2 as described above.
[0004]
[Problems to be solved by the invention]
Since the inner diameter surface 2c of the inner ring 2 has a tapered shape, the wall surfaces t1 and t2 from the inner ring inner diameter surface to the raceway surfaces 2a and 2b are different in the raceway surfaces 2a and 2b. Since the amount of expansion of the raceway surfaces 2a and 2b due to the fitting varies depending on the thickness, as shown in FIG. 5, the mutual difference δ _S between the radial gaps between the two rows of raceway surfaces 2a and 2b is increased. Get out. This mutual difference δ _S becomes an expansion amount difference S between the columns.
If this mutual difference δ _S is large, the bearing load concentrates on the rolling elements 4a in the rows with small radial gaps, so that abnormal heat generation and early separation of the bearings may occur. In addition, the accuracy of the taper angle between the shaft 6 and the inner ring 2 is poor, and when the shaft 6 and the inner ring 2 are extremely non-uniformly fitted, the probability of occurrence of the above heat generation and early peeling problems increases.
[0005]
An object of the present invention is an assembly of a cylindrical roller bearing and a shaft and a design thereof, in which the radial gap between the raceways of the double row after fitting is small, and abnormal heat generation and early separation of the bearing can be prevented. Is to provide a method .
[0007]
[Means for Solving the Problems]
The assembly of this inventions the cylindrical roller bearing and the shaft, the axis having a cylindrical roller bearing of double row inner ring having an inner diameter surface and a tapered surface, the tapered portion fitted state interference fit to the inner diameter surface of the inner ring When the inner diameter surface of the inner ring is manufactured aiming at a desired reference taper angle, and the taper angle of the taper portion of the shaft is manufactured aiming at −3 seconds with respect to the reference taper angle, The tolerance of the taper angle with respect to the target angle of the taper part of the shaft and the inner ring inner surface,
If the bearing width is larger than 37 mm, both the shaft and inner ring should be in the range of -3 seconds to +3 seconds.
When the bearing width is 37 mm or less, both the shaft and inner ring are in the range of -6 seconds to +6 seconds.
It is characterized by that.
In the case of this configuration, since the tolerance of the taper angle after processing with respect to the target angle of the taper portion of the shaft and the inner ring inner surface is within the above range, between the two rows of raceway surfaces after fitting the shaft and the bearing, The difference between the radial gaps becomes smaller than a predetermined value. For this reason, there is no concentration of bearing load on one of the rolling element rows, and abnormal heat generation and early separation of the bearing are prevented.
[0008]
Design method for the assembly of the cylindrical roller bearing and the shaft of this invention, a cylindrical roller bearing of double row inner ring having an inner diameter surface and a tapered surface, the tapered portion to be fitted in a state close fit to the inner diameter surface of the inner ring The difference in the taper angle at which the difference in expansion between the raceways of the double row in the inner ring is not more than a predetermined value, and the relationship between the taper angle difference and the bearing width is analyzed by a finite element method. The difference in taper angle between the taper portion of the shaft and the inner ring inner surface (the taper angle of the shaft minus the taper angle of the inner ring inner surface) is determined by the difference between the calculated taper angle and the bearing width. From the relationship, if the bearing width is larger than 37 mm, the range is -9 seconds to +3 seconds.
When the bearing width is 37 mm or less, the range is from -15 seconds to +9 seconds,
It is characterized by that. In this case, the difference in radial gap between the two rows of raceway surfaces after fitting the shaft and the bearing becomes smaller than a predetermined value. For this reason, there is no concentration of bearing load on one of the rolling element rows, and abnormal heat generation and early separation of the bearing are prevented.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The assembly of the rolling bearing and the shaft according to the first proposal Examples and shaped state that is a basis of the present invention will be described in conjunction with FIG. The assembly of the rolling bearing and the shaft is composed of a double row rolling bearing 1 and a shaft 6, the inner surface 2 c of the inner ring 2 of the rolling bearing 1 is a tapered surface, and the shaft 6 is formed on the inner surface 2 c of the inner ring 2. It has the taper part 6a to fit. The shaft 6 is a main shaft in a machine tool, for example.
The inner ring 2 and the outer ring 3 of the rolling bearing 1 have two rows of raceway surfaces 2a, 2b, 3a, 3b arranged in the axial direction, and the rolling elements 4a, 4b in each row are arranged between the raceway surfaces facing each other. Yes. The rolling elements 4a and 4b in each row are held in a cage 5 provided for each row. The rolling bearing 1 is a cylindrical roller bearing, and the rolling element 4 is composed of rollers. The inner ring 2 has flanges 7 and 8 on both sides and the center, the outer ring 3 has no flanges, and the two rows of raceway surfaces 3a and 3b are formed in a continuous cylindrical surface.
The materials of the inner ring 2, the outer ring 3, and the rolling elements 4a and 4b are made of steel such as bearing steel. The above is the basic configuration.
[0010]
In the first proposed example , the difference in taper angle between the tapered portion 6a of the shaft 6 and the inner diameter surface 2c of the inner ring 2 (shaft taper angle−taper angle of the inner ring inner diameter surface)
When the bearing width B is larger than 37 mm, the range is -9 seconds to +3 seconds.
When the bearing width B is 37 mm or less, a range of -15 seconds to +9 seconds,
It is what.
[0011]
An embodiment of the present invention will be described. This implementation embodiment in the above basic structure, the inner surface 2c of the inner ring 2 made aiming at the desired reference taper angle, and the -3 seconds taper angle of the tapered portions 6a of the shaft 6 with respect to the reference taper angle Aim to produce. In this case, the tolerance of the taper angle with respect to the target angle of the tapered portion 6a of the shaft 6 and the inner ring inner surface 2c is as follows.
When the bearing width B is larger than 37 mm, both the shaft 6 and the inner ring 2 are in the range of -3 seconds to +3 seconds,
When the bearing width B is 37 mm or less, both the shaft 6 and the inner ring 2 are set in the range of −6 seconds to +6 seconds.
The desired reference taper angle is, for example, a reference taper ratio of 1/12 or 1/30, which is a taper ratio usually employed.
[0012]
According to the configuration of the first proposed embodiment Oyo BiMinoru facilities embodiment, any two rows of the raceway surfaces 2a, the smaller the relative difference of the radial clearance between 2b, preventing overheating and premature flaking of the rolling bearing 1 can do. The reason will be described below.
[0013]
The difference in expansion between the two rows of raceway surfaces 2a and 2b of the inner ring 2 fitted to the shaft 6 is
(1) An angular difference between the taper angle of the shaft 6 and the taper angle of the inner ring inner surface 2c, and
(2) Inner ring 2 tightening allowance,
As a result of FEM (finite element method) analysis and experiment verification, it was found that the calculation was based on
S = a × Δα + b × Y + c (1)
However,
S: Expansion amount difference (μm) between two raceways of the inner ring,
(= Large-diameter track diameter expansion amount of the inner ring inner diameter surface−Small-diameter track diameter expansion amount),
Δα: Angle difference (in seconds) between shaft taper angle and inner ring inner surface taper angle,
(= Shaft taper angle-bearing inner surface taper angle),
Y: Inner ring tightening margin (μm) given to the axial center of the raceway surface on the inner ring inner diameter surface smaller diameter side
a, b, c: Constants set for each combination of shaft and bearing used.
The constants a, b, and c are numerical values determined by FEM analysis or experiment.
[0014]
In the range of the inner ring interference allowance Y that is normally used as the main spindle of a machine tool, the angular difference between the shaft taper angle at which the expansion difference S between the two rows of raceway surfaces 2a and 2b is ± 1 μm or less and the inner ring inner surface taper angle As a result of calculating Δα for the bearings of various model numbers using the above equation (1), FIG. 2 was obtained. The reason why the expansion difference S is set to ± 1 μm or less is defined as a substantially maximum range where it is understood from the experience so far that problems such as abnormal heat generation and early peeling do not occur in the bearing. The vertical axis in FIG.
[0015]
From FIG. 2, for bearings with a bearing width B greater than 37 mm, the angle difference Δα is about −9 to +3 seconds (median −3 seconds), and for bearings with a bearing width B of 37 mm or less, the angle difference Δα is about − From 15 seconds to +9 seconds (median value -3 seconds), it can be seen that the expansion difference S between the two rows of raceway surfaces 2a and 2b is ± 1 μm or less. Strictly speaking, it can be seen from FIG. 2 that the range of the angle difference Δα is different for each model number, and the median value thereof is different, but it is inconvenient to change the target value (median value) for each model number. Therefore, the range of the angle difference Δα was determined as described above.
[0016]
A normal bearing is manufactured using a reference taper ratio of 1/12 or 1/30 as a taper surface of the inner ring inner surface 2c. Since it is known from FIG. 2 that the angle difference [Delta] [alpha] should be a median value of -3 seconds, the taper angle of the shaft may be manufactured at a taper reference angle of the inner ring inner diameter surface of -3 seconds.
Moreover, when the range of the angle difference Δα is assigned as a tolerance to the taper angle between the bearing and the shaft, the taper surface of the bearing inner diameter surface is manufactured aiming at a desired reference angle, and the taper portion of the shaft is formed on the inner ring inner surface. When the bearing is manufactured with a reference angle of -3 seconds, if the bearing width B is greater than 37 mm, both the shaft 6 and the inner ring 2 are ± 3 seconds. If the bearing width B is 37 mm or less, both the shaft 6 and the inner ring 2 are ± 6 seconds. When the taper angle between the shaft 6 and the inner ring 2 is manufactured in this way, after the inner ring 2 and the shaft 6 are fitted, the mutual difference in radial gap between the two rows of raceway surfaces 2a and 2b becomes ± 1 μm. Therefore, abnormal heat generation and early peeling of the rolling bearing 1 can be prevented.
[0017]
Next, another reference proposal example of the present invention will be described with reference to FIG. This example of the reference proposal is based on the basic configuration described with reference to FIG. 1, and the difference in expansion between the two raceways 2a and 2b of the inner ring 2 is estimated by calculation for the rolling bearing 1, and this amount is used as a radial clearance when the bearing alone. It is given as a mutual difference (difference between radial gaps in each row).
For example, when it is calculated that the B row expands by 1 μm larger than the radial clearance of the raceway surface 2a of the A row of the inner ring 2 when the bearing is assembled, the radial clearance of the raceway surface 2b of the B row is A It is 1 μm smaller than the row. In order to reduce the radial gap in the B row, for example, a larger rolling element 4b in the B row than the rolling element 4a in the A row is used.
As a result, the radial clearance when the rolling bearing 1 is incorporated into the shaft 6 can be made the same on the raceway surfaces 2a and 2b of each row. This method is particularly effective when the taper angle of the shaft 6 is formed at the same angle as the taper angle of the inner ring inner surface. If this method is used when the taper angle of the shaft 6 is formed on the inner ring inner surface 2c, the angle difference Δα will not vary and the angle difference Δα = 0 will always be obtained, so the expansion amount difference S can be reduced more accurately. can do. Further, after measuring the taper angle between the shaft 6 and the inner ring inner surface 2c, the radial difference between the bearings alone may be determined by calculation and adopted.
[0019]
【Example】
Example 1
In the 1st proposal example demonstrated with FIG. 1, the dimension of each part of the rolling bearing 1 was made into the following value. That is, the inner diameter D1 of the inner ring 2 was 130 mm, the outer diameter D2 was 200 mm, and the bearing width B was 52 mm. Shaft 6 is a hollow shaft, the inner diameter _{d i} is 78mm.
In the case of the rolling bearing 1 having this size, it was determined by FEM analysis that the above equation (1) becomes the following equation (2).
S = 0.1064 × Δα + 0.0092 × Y + 0.004 (2)
At this time, the taper angle of the taper portion 6a of the shaft 6 was processed with a reference angle +9 seconds ± 3 seconds, and the taper angle of the inner ring inner surface 2c was processed with a reference angle + 12 seconds ± 3 seconds. That is, the angle difference Δα = −9 to +3.
[0020]
In the case of the bearing 1 of this embodiment, the range of the tightening allowance Y of the inner ring 2 that is normally used as the main shaft of the machine tool is 20 to 70 μm. When the angle difference Δα and Y are substituted into the equation (2), S = −0.77 to +0.97 μm. Therefore, the expansion amount difference S between the two rows of raceway surfaces 2a and 2b due to the fitting between the shaft 6 and the inner ring 2 is suppressed to 1 μm or less. Therefore, the possibility of abnormal heat generation and early peeling in the bearing 1 can be reduced.
[0021]
( Test example )
In other reference proposal examples described in conjunction with FIG. 3, as in the first embodiment, the inner diameter D1 of the bearing inner ring 2 is 130 mm, the outer diameter D2 is 200 mm, and the bearing width B is 52 mm as shown in FIG. Shaft 6 is a hollow shaft, the inner diameter _{d i} is 78mm.
In this case, it was found that the taper angle of the taper portion 6a of the shaft 6 was the reference angle +6 seconds, and the taper angle of the inner ring inner surface 2c was the reference angle +14 seconds. That is, the angle difference Δα = 6-14 = −8.
Since the range of the tightening allowance Y of the inner ring 2 is 20 to 70 μm, if the expansion amount difference S between the two rows of raceway surfaces 2a and 2c due to the fitting of the shaft 6 and the inner ring 2 is calculated by the equation (2), S = −0.66 to −0.20 μm, and the median was about −0.4 μm. At this time, when the rolling element 4b having a diameter 0.2 μm larger than that of the large-diameter side raceway surface 2a is inserted into the small-diameter side raceway surface 2b of the inner ring inner diameter surface 2c when the bearing alone is used, the shaft 6 and the inner ring 2 are fitted. The expansion amount difference S between the two rows of raceway surfaces 2a and 2b is suppressed to S = −0.26 to +0.20 μm. Therefore, it is possible to reduce the possibility of abnormal heat generation and early peeling in the rolling bearing 1.
[0022]
【The invention's effect】
Assembly of the inventions of the cylindrical roller bearing and the shaft of this becomes more a shaft having a cylindrical roller bearing of double row inner ring having an inner diameter surface and a tapered surface, the tapered portion fitted to the inner diameter surface of the inner ring When the inner diameter surface of the inner ring is manufactured aiming at a desired reference taper angle and the taper angle of the taper portion of the shaft is aimed at -3 seconds with respect to the reference taper angle, The tolerance of the taper angle with respect to the target angle of the tapered part and the inner ring inner surface is set within a predetermined range, so that the radial gap between the raceways of the double row after fitting is small, preventing abnormal heat generation and premature peeling of the bearing. it can be.
Design method for the assembly of the cylindrical roller bearing and the shaft of this invention, a cylindrical roller bearing of double row inner ring having an inner diameter surface and a tapered surface, the tapered portion to be fitted in a state close fit to the inner diameter surface of the inner ring The difference in the taper angle at which the difference in expansion between the raceways of the double row in the inner ring is not more than a predetermined value, and the relationship between the taper angle difference and the bearing width is analyzed by a finite element method. The difference in taper angle between the taper portion of the shaft and the inner ring inner surface (the taper angle of the shaft minus the taper angle of the inner ring inner surface) is determined by the difference between the calculated taper angle and the bearing width. From the relationship, when the bearing width is larger than 37 mm, the range is -9 seconds to +3 seconds. When the bearing width is 37 mm or less, the range is -15 seconds to +9 seconds. The difference in radial clearance between Atmospheric heating and premature flaking can be prevented.
[Brief description of the drawings]
FIG. 1 is a sectional view of an assembly of a rolling bearing and a shaft according to a first embodiment of the present invention.
FIG. 2 is a view showing a relationship between a bearing width and a taper angle difference at which a difference in expansion amount is a predetermined value or less in the assembly.
FIG. 3 is a cross-sectional view of an assembly of a rolling bearing and a shaft according to another reference proposal example .
FIG. 4 is a cross-sectional view of a conventional example.
FIG. 5 is an operation explanatory diagram of the conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Rolling bearing 2 ... Inner ring 2a, 2b ... Raceway surface 2c ... Inner diameter surface 3 ... Outer ring 4 ... Rolling element 6 ... Shaft 6a ... Tapered part

Claims (2)

It consists of a double row cylindrical roller bearing having an inner diameter surface of the inner ring as a tapered surface, and a shaft having a tapered portion that fits into the inner diameter surface of the inner ring.
When the inner diameter surface of the inner ring is manufactured aiming at a desired reference taper angle, and the taper angle of the taper portion of the shaft is aimed at -3 seconds with respect to the reference taper angle, the taper portion of the shaft And the tolerance of the taper angle with respect to the target angle of the inner ring inner surface,
If the bearing width is larger than 37 mm, both the shaft and inner ring should be in the range of -3 seconds to +3 seconds.
When the bearing width is 37 mm or less, both the shaft and inner ring are in the range of -6 seconds to +6 seconds.
An assembly of a cylindrical roller bearing and a shaft characterized by the above. A double row cylindrical roller bearing having a tapered inner surface on the inner ring, and a shaft having a tapered portion that fits tightly on the inner surface of the inner ring, and the expansion amount of the double row raceway surface in the inner ring The difference in taper angle at which the difference is a predetermined value or less, and the relationship between the taper angle difference and the bearing width is determined based on finite element method analysis and experimental verification,
The difference in taper angle between the tapered part of the shaft and the inner ring inner diameter surface (taper taper angle−taper angle of the inner ring inner diameter surface) is determined from the relationship between the obtained taper angle difference and the bearing width. In this case, the range is from -9 seconds to +3 seconds.
When the bearing width is 37 mm or less, the range is from -15 seconds to +9 seconds,
A method for designing an assembly of a cylindrical roller bearing and a shaft, characterized in that

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