KR-102963508-B1 - Angular ball bearings

KR102963508B1KR 102963508 B1KR102963508 B1KR 102963508B1KR-102963508-B1

Abstract

An angular ball bearing comprises an inner ring having an inner ring raceway groove with a cross-sectional arc on its outer surface, an outer ring having an outer ring raceway groove with a cross-sectional arc on its inner surface, and a plurality of balls formed to freely move between the inner ring raceway groove and the outer ring raceway groove. The ratio of the radius of curvature of the inner ring raceway groove to the ball diameter, Ri, is 54 to 58%, and the ratio of the radius of curvature of the outer ring raceway groove to the ball diameter, Ro, is 51 to 58%, and Ri ― Ro ≥ 0 points. Additionally, at least the inner ring raceway groove has a maximum surface pressure of 4.7 to 6.0 GPa when the sum of the permanent deformation amounts of the ball and the inner ring raceway groove at the center of the contact portion between the ball and the inner ring raceway groove is 1/10,000 of the ball diameter. By doing so, an angular ball bearing is provided that can reduce heat generation and suppress damage caused by external impact loads when stationary.

Inventors

소가 슈지
가츠노 요시아키

Assignees

닛본 세이고 가부시끼가이샤

Dates

Publication Date: 20260511
Application Date: 20210915
Priority Date: 20200928

Claims (9)

An inner ring having an inner ring raceway groove in the shape of a cross-sectional arc on the outer surface, and An outer ring having an outer ring raceway groove in the shape of a cross-sectional arc on its inner surface, and An angular ball bearing having a plurality of balls formed to freely move between the inner ring raceway groove and the outer ring raceway groove, The ratio of the groove radius of curvature of the inner ring raceway groove to the ball diameter (Ri) is 54 to 58%, the ratio of the groove radius of curvature of the outer ring raceway groove to the ball diameter (Ro) is 51 to 58%, and also Ri ― Ro ≥ 0 points, together with An angular ball bearing characterized by having a surface hardened layer formed at least in the inner ring raceway groove by surface hardening treatment, such that the maximum surface pressure is 4.7 to 6.0 GPa when the sum of the permanent deformation amounts of the ball and the inner ring raceway groove at the center of the contact portion between the ball and the inner ring raceway groove is 1/10,000 of the ball diameter.
In Article 1, Angular ball bearing with Ri ― Ro ≥ 1 point.
In Article 1, An angular ball bearing in which a surface hardened layer formed by machining is formed in at least the inner ring raceway groove.
In Article 1, An angular ball bearing in which a surface hardened layer formed by machining is formed only in the inner ring raceway groove among the inner ring raceway groove and the outer ring raceway groove.
In any one of paragraphs 1 to 4, An angular ball bearing in which the material of the ball is ceramic.
In any one of paragraphs 1 to 4, Angular ball bearing having a ball diameter/cross-sectional height ratio of 0.39 to 0.65.
In Article 6, An angular ball bearing having a ratio of ball diameter to cross-sectional height of 0.55 to 0.65.
In any one of paragraphs 1 to 4, An angular ball bearing used in machine tool spindles of 800,000 or more, and is an angular ball bearing with preload applied.
In any one of paragraphs 1 to 4, At least one of the inner ring and the outer ring is made of steel containing C: 0.2 to 1.2 mass%, Si: 0.7 to 1.5 mass%, Mo: 0.5 to 1.5 mass%, Cr: 0.5 to 2.0 mass%, the remainder being Fe and unavoidable impurity elements, and also, An angular ball bearing having a surface carbon concentration of 0.8 to 1.3 mass% and a surface nitrogen concentration of 0.2 to 0.8 mass%.

Description

Angular ball bearings The present invention relates to an angular ball bearing, and in particular, to a ball bearing used for main spindles for various machine tools, motors, etc. Recently, machine tools have been increasing the speed of their spindles to improve machining efficiency and productivity, and consequently, the rotational speed of angular ball bearings used in machine tool spindles is also rising. Generally, when angular ball bearings rotate at high speeds, significant slippage occurs at the contact points between the balls and the raceway due to spin or gyroscopic motion. Additionally, the internal clearance of the bearing decreases due to the influence of centrifugal forces acting on the inner ring or balls, increasing the contact pressure between the balls and the raceway. Consequently, heat generation increases. As the amount of heat increases, the viscosity of the oil decreases, causing the oil film to break at the rolling contact area between the balls and the raceway. This leads to problems such as bearing sheathing, increased thermal displacement of the spindle, and deterioration of machining precision. Conventional techniques for reducing heat generation in angular ball bearings include, for example, setting the ratio of the groove curvature radius of the outer ring to 50.5 to 53% and the ratio of the groove curvature radius of the inner ring to 52.5 to 60% (see Patent Document 1), or setting the ratio of the groove curvature radius of both the outer ring and the inner ring to 54 to 57% (see Patent Document 2). FIG. 1 is a partially enlarged cross-sectional view of an angular ball bearing, which is an example of a ball bearing of the present invention. Figure 2 is a schematic diagram illustrating spin slip. Figure 3 is a schematic diagram for explaining spin slipping, showing an enlarged view of the inner ring raceway groove of the inner ring. FIG. 4 is a schematic diagram for explaining spin slip, FIG. 4(a) is a diagram showing the direction in which centrifugal force acts, FIG. 4(b) is a diagram showing the amount of spin when the ratio of the inner ring groove curvature radius is large, and FIG. 4(c) is a diagram showing the amount of spin when the ratio of the inner ring groove curvature radius is small. Figure 5 is a graph obtained from calculation showing the relationship between the inner ring groove curvature radius ratio (Ri) and the total spin heat generation amount between the inner ring side and the outer ring side under analysis condition 1. Figure 6 is a graph obtained from calculation showing the relationship between the outer ring groove curvature radius ratio (Ro) and the total spin heat generation amount of the inner ring side and the outer ring side under analysis condition 1. Figure 7 is a graph showing the relationship between Ri ― Ro and the ratio of inner ring surface pressure to outer ring surface pressure obtained from the calculated values under analysis condition 1. Figure 8 is a graph obtained from calculation showing the relationship between the inner ring groove curvature radius ratio (Ri) and the total spin heat generation amount between the inner ring side and the outer ring side under analysis condition 2. Figure 9 is a graph obtained from calculation showing the relationship between the outer ring groove curvature radius ratio (Ro) and the total spin heat generation amount of the inner ring side and the outer ring side under analysis condition 2. Figure 10 is a graph obtained from calculation showing the relationship between the inner ring groove curvature radius ratio (Ri) and the total spin heat generation amount between the inner ring side and the outer ring side under analysis condition 3. Figure 11 is a graph obtained from calculation showing the relationship between the outer ring groove curvature radius ratio (Ro) and the total spin heat generation amount between the inner ring side and the outer ring side under analysis condition 3. Figure 12 is a graph obtained from calculation showing the relationship between the inner ring groove curvature radius ratio (Ri) and the total spin heat generation amount between the inner ring side and the outer ring side under analysis condition 4. Figure 13 is a graph obtained from calculation showing the relationship between the outer ring groove curvature radius ratio (Ro) and the total spin heat generation amount between the inner ring side and the outer ring side under analysis condition 4. Hereinafter, an angular ball bearing related to an embodiment of the present invention will be described in detail with reference to the drawings. Additionally, in this specification, "∼" indicating a numerical range is used to mean that the values described before and after it are included as lower and upper limits. FIG. 1 illustrates an angular ball bearing used in a main spindle for a machine tool as an example of an angular ball bearing of the present invention. An angular ball bearing (1) comprises an inner ring (2) h