JP4364610B2 - Roller bearing - Google Patents

Description

  The present invention relates to a crowning shape of a roller rolling surface or a raceway surface in a roller bearing, and more specifically, roller rolling in a cylindrical roller bearing (FIG. 1B) and a tapered roller bearing (FIG. 1C). It can be applied to moving surfaces and inner and outer raceways.

  When the contact part is in line contact like a roller bearing, the surface pressure distribution in the axial direction is generated almost uniformly to extend the fatigue life, and no edge stress is generated at the end face of the contact part even in a misaligned state. It is necessary to do so. Misalignment refers to, for example, a shaft system in which both ends are supported by two bearings, and the bearing centers of both ends are mounted so as to be displaced in a direction perpendicular to the axis, thereby causing the raceway surface and rolling element of the inner ring or outer ring. This is a state where the rolling surface is relatively inclined.

  As one of the prior arts, Japanese Utility Model Laid-Open No. 5-22845 describes a device related to the crowning shape of a tapered roller bearing. The generatrix of the roller rolling surface is a straight line, trapezoidal crowning is applied to the inner ring raceway surface, and full crowning is applied to the outer ring raceway surface to prevent galling with the end face of the collar when tilting.

  Japanese Utility Model Laid-Open No. 5-89943 discloses a device formed by a flat surface and three stages of crowning.

  Japanese Patent Laid-Open No. 8-232960 describes a device in which the center of the full crowning is offset to the large end face in order to prevent edge loading in a tapered roller bearing structure with a cantilever support structure.

Japanese Patent Laid-Open No. 2000-257637 is characterized in that a bus is divided into a plurality of zones and the shape of the bus is approximated by an arc for each zone or formed into a shape that satisfies a theoretical value. .
Japanese Patent Application Laid-Open No. 2000-346078 discloses that the equivalent stress distribution in the longitudinal direction is made uniform, and the damage received by the material in the vicinity of the contact surface in the longitudinal direction of the contact region is evenly distributed. It is a device that presents a crowning curve that gives static or dynamic load capacity.

  In JP 2001-65574 A, the sum of the crowning amount on the rolling element side and the inner ring raceway surface side defines the drop amount at two points (X = 0.425 Le) in the roller bus line direction from the center of the rolling element or the race ring. It is characterized by satisfying the following formula. Alternatively, a linear portion 0.5 to 0.9 times the effective contact length is provided, and a partial crowning composed of a curved portion having a radius 50 to 125 times the effective length is provided at both ends thereof. .

  Japanese Patent Application Laid-Open No. 2001-82114 discloses a crowning device relating to a tappet roller, in which an upper limit and a lower limit of a crowning drop amount δ at a position x in the axial direction are determined by a formula with the center as an origin. It also presents a method for defining the crowning profile so that it exists between logarithmic crownings at positions 0.85 times and 1.0 times half the effective contact length.

  Japanese Patent Application Laid-Open No. 2001-124089 has a shape obtained by approximating a crowning curve related to a cylindrical roller bearing by an exponential function. This shape is not particularly considered for misalignment.

  Japanese Patent Laid-Open No. 2001-241446 discloses a device in which a straight line portion and a crowning portion of a bus bar shape are connected so as to share a tangent line, and a contact angle of an outer ring raceway surface is 12 to 17 °. Yes.

In Japanese Patent Application Laid-Open No. 2002-235749, a crowning curve is composed of a combination of circular arcs, and is expressed as a function, but is represented by the slope of the curve. Absent. Further, the present invention is not particularly considered for misalignment, and is not applicable when the contact surface is short.
Japanese Utility Model Publication No. 5-22845 Japanese Utility Model Publication No. 5-89943 JP-A-8-232960 Japanese Patent Application Laid-Open No. 2000-257637 JP 2000-346078 A JP 2001-65574 A JP 2001-82114 A JP 2001-1224089 A JP 2001-241446 A Japanese Patent Laid-Open No. 2002-235749

When the contact part is in line contact like a tapered roller bearing, the axial surface pressure distribution is generated almost uniformly to extend the fatigue life, and the inner and outer rings and the rolling elements are relatively inclined. It is necessary to prevent edge stress from being generated at the end face of the contact portion even in the misaligned state.
An object of the present invention is to provide a crowning curve that does not cause an edge load even when misalignment occurs in a contact portion between a rolling element and a bearing ring of a rolling bearing having a line contact portion, and has a long fatigue life. is there.

In the first aspect of the present invention, the ratio l / D of the contact length 1 excluding the chamfer width from the roller total length to the roller diameter D is 1 . A roller bearing having 5 or less rollers, wherein at least one of the inner ring raceway surface, the outer ring raceway surface, and the roller rolling surface has a crowning, and the shape of the crowning is expressed by the following formula (1): A roller bearing obtained by satisfying 4 ≦ K ₁ ≦ 1.7 and −20 ≦ K ₂ ≦ −10.

The invention of claim 2 is a roller bearing used under misalignment, wherein at least one of the inner ring raceway surface, the outer ring raceway surface and the roller rolling surface has a crowning, and the shape of the crowning is expressed by the formula ( 1) Based on 1), K ₁ = 1.4, K ₂ = −10, the maximum drop amount z _{m at} which no edge load is generated is obtained, and the crowning length x is obtained from the formula (2). A roller bearing characterized by being x _m or less.

According to the present invention, for the contact length l where the chamfer width is removed from the total length of the roller, the l / D is 1 . For a roller of 5 or less, if 1.4 ≦ K ₁ ≦ 1.7 and −20 ≦ K ₂ ≦ −10, the minimum maximum drop amount at which no edge load occurs is obtained from Equations 1 and 2, the load is large. However, the edge load is not generated when there is misalignment, and the maximum surface pressure can be minimized when there is no misalignment.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  It is known that an edge load greater than the contact surface pressure at the center of the contact portion occurs at the end portion of the object that makes line contact, and the fatigue life is shortened. In order to prevent this, a method of making the rolling element surface into a convex curve has been widely adopted and is called the technical term “crowning”.

  Regarding the optimal crowning curve, Johns, PM and Gohar, R. described the optimal rolling element curve represented by equation (3) in "Roller bearings under radial and eccentric loads" (TRIBOLOGY international June 1981 pp.131-136). Advocated.

Here, z is the amount of crowning drop, Q is the load, ν is the Poisson's ratio, l is the contact part length, E is the Young's modulus, _bo is the contact half width at the center of the contact part, a is ½ of the contact part length, x represents an axial length (see FIG. 1A). 1B shows a cross section of the cylindrical roller bearing, and FIG. 1C shows a cross section of the tapered roller bearing. In either case, a plurality of rollers 6a and 6b are rotatably interposed between the raceways of the inner rings 2a and 2b and the outer rings 4a and 4b. Retained.

  As a calculation example, a contact portion between a φ10 × 10 roller and a φ50 × 15 steel roller is taken up. When crowning is performed on a φ10 × 10 roller, the crowning shape of Equation (3) under the calculation conditions shown in Table 1 is as shown in FIG. At this time, the bus of the φ50 × 15 steel roller is a straight line.

In Table 1, when the crowning is not performed, the contact half width b _{0 at the} center of the contact portion is obtained by Expression (4).

However, R is an equivalent radius and is calculated | required by following Formula.
1 / R = 1 / R ₁ + 1 / R ₂
Here, R ₁ and R ₂ are the radii of the respective contact portions.
E ′ is called an equivalent elastic modulus and is obtained by the following equation.
1 / E ′ = (1−ν ² ) / E
FIG. 3 shows the contact surface pressure calculated based on elastic mechanics when the misalignment is 0 and a load of 9.81 kN is applied to the crowning shape of FIG. Under high surface pressure, an increase in surface pressure is observed at the end. When misalignment 3/1000 is given to this time, the surface pressure distribution becomes as shown in FIG. 4, and this tendency becomes remarkable.

In consideration of misalignment, it is necessary to modify equation (3) in order to use equation (3) for the design of the rolling element shape. Therefore, the constant term of Equation (3) is parameterized, and K ₁ and K ₂ are introduced and given as Equation (5).

The crowning curve is obtained by optimizing the coefficients K ₁ and K ₂ in the equation (5). Mainly, K ₁ means that the crowning design is determined in consideration of a load larger than the design load. The crowning region is determined by K ₁ , K ₂ and the maximum drop amount z _m as given by equation (6).

FIG. 5 to FIG. 7 show the results of calculating the influence of K ₁ , K ₂ , and z _m on the maximum surface pressure of each roller when misalignment = 3/1000. When the ratio l / D of the roller contact length 1 excluding the chamfer width from the roller total length to the roller diameter D is 0.7 in FIG. 5, 1.0 in FIG. 6, and 1.5 in FIG. It is. From these figures, it can be seen that edge load does not occur when 1.4 ≦ K ₁ ≦ 1.7. As shown in FIGS. 5 (b), 6 (c), and 7 (b), the influence of K ₂ is not so much, but when K ₁ is small or z _m is small, K ₂ is small. Edge load is unlikely to occur. Thus, K ₂ is smaller. However good, there is a tendency that a maximum surface pressure is slightly Smaller K _2, 1% of the surface pressure increase in K ₂ = -20 are seen for K ₂ = 0. Therefore, −20 ≦ K ₂ ≦ 0 is desirable.

  Next, the surface pressure distribution when the parameters in Table 2 are used is shown in FIGS. It can be seen that edge loading does not occur at misalignment = 3/1000.

When 1 / D = 1.5, z _m = 15 μm, K ₁ = 1.3, K ₂ = −10 or K ₁ = 1.4, and K ₂ = 0, as shown in FIGS. 11 and 12, respectively. In FIG. 13, edge load does not occur even when K ₁ = 1.4 and K ₂ = −10. That is, when there is misalignment, if z _m is constant, it is necessary to make K ₂ -10 or less and lengthen the straight portion. Therefore, if there is misalignment, K ₁ = 1.4 and K ₂ = −10 are used to obtain z _m where no edge load occurs, and when this z _m is not changed, the crowning region is set to K ₁ = 1.4. , K ₂ = −10, and x _m determined by Equation 6 must be given.

  In addition, the roller bearing of the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention.

a is a diagram showing a crowning shape, b is a sectional view of a cylindrical roller bearing, and c is a sectional view of a tapered roller bearing. It is a diagram which shows a crowning shape. a is a diagram showing a contact surface pressure distribution, and b is an enlarged view of an end portion in a. a is a diagram showing a contact surface pressure distribution, and b is an enlarged view of an end portion in a. a is a graph showing the relationship between K ₁ and the maximum surface pressure, b is a graph showing the relationship between K ₂ and the maximum surface pressure, and c is a graph showing the relationship between z _m and the maximum surface pressure. a is a graph showing the relationship between K ₁ and the maximum surface pressure, b is a graph showing the relationship between z _m and the maximum surface pressure, and c is a graph showing the relationship between K ₂ and the maximum surface pressure. a is a graph showing the relationship between K ₁ and the maximum surface pressure, b is a graph showing the relationship between K ₂ and the maximum surface pressure, and c is a graph showing the relationship between z _m and the maximum surface pressure. a is a diagram showing a contact surface pressure distribution, and b is an enlarged view of an end portion in a. a is a diagram showing a contact surface pressure distribution, and b is an enlarged view of an end portion in a. a is a diagram showing a contact surface pressure distribution, and b is an enlarged view of an end portion in a. a is a diagram showing a contact surface pressure distribution, and b is an enlarged view of an end portion in a. a is a diagram showing a contact surface pressure distribution, and b is an enlarged view of an end portion in a. a is a diagram showing a contact surface pressure distribution, and b is an enlarged view of an end portion in a.

Explanation of symbols

2a, 2b Inner ring 4a, 4b Outer ring 6a, 6b Roller 8a, 8b Cage

Claims (2)

The ratio l / D of the contact length 1 excluding the chamfered width from the roller length to the roller diameter D is 1 . A roller bearing having 5 or less rollers, wherein at least one of the inner ring raceway surface, the outer ring raceway surface, and the roller rolling surface has a crowning, and the shape of the crowning is expressed by the following formula (1): A roller bearing obtained by satisfying 4 ≦ K ₁ ≦ 1.7 and −20 ≦ K ₂ ≦ −10.
A roller bearing used under misalignment, wherein at least one of the inner ring raceway surface, the outer ring raceway surface and the roller rolling surface has a crowning, and the shape of the crowning is expressed as K ₁ based on the formula (1). = 1.4, K ₂ = −10, the maximum drop amount z _{m at} which no edge load occurs is obtained, and the crowning length x is set to be equal to or less than the maximum crowning length x _m obtained from the equation (2). A featured roller bearing.