JP2009168090A - Double-row rolling bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure improving durability in a double-row rolling bearing unit, including an outer ring 3, in which clean metal material is exposed in both of double rows of outer ring raceways 2 and 2 provided on the inner circumferential surface of the outer ring 3. <P>SOLUTION: In a cross section at a supposed plane including the center axis of the outer ring 3, plasticity flow lines as the directions of plastic deformation of the metal material composing the outer ring 3 do not cross any of generating lines of both outer ring raceways 2 and 2. A start point of the plasticity flow lines are set to exist in axial direction intermediate parts of shoulder parts 21 existing between both outer ring raceways 2 and 2. The start point is set at a position between the width direction center of the shoulder part 21 and less than 1/4 of the width of the shoulder part 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improvement in a bearing outer ring among double row rolling bearing units constituting a rotation support portion for rotatably supporting wheels of various vehicles such as automobiles and railway vehicles. A bearing outer ring incorporated in a double-row rolling bearing unit that is an object of the present invention includes a double-row back combination type outer ring raceway at two positions in the axial direction of the inner peripheral surface. In such a bearing outer ring, the outer peripheral surface is a cylindrical surface whose outer diameter does not substantially change in the axial direction, and the inner peripheral surface has the smallest inner diameter in the axial direction intermediate portion. However, the shape is inclined in a direction in which the inner diameter gradually increases as it goes toward both ends in the axial direction. The cylindrical surface whose outer diameter does not substantially change in the axial direction refers to a shape in which the outer diameter does not change except for chamfered portions provided at both end edges in the axial direction. Moreover, if the double row rolling bearing unit used as the object of the present invention is a double row, it is not limited to a ball bearing but also includes a tapered roller bearing.

  In order to rotatably support the wheels of various vehicles, a double-row angular ball bearing 1 of a rear combination type as shown in FIG. 8 is widely used. This double-row angular ball bearing 1 includes an outer ring 3 having double-row outer ring raceways 2 and 2 on its inner peripheral surface, a pair of inner rings 5 and 5 having inner ring raceways 4 formed on their outer peripheral surfaces, A plurality of balls 6, 6 are provided between the outer ring raceways 2, 2 and the inner ring raceways 4, 4 of the inner races 5, 5, respectively, for holding these balls 6, 6. A pair of cages 7 and 7 are provided. In such a double-row angular ball bearing 1, for example, the outer ring 3 is fitted and fixed to the housing 8, and the inner rings 5 and 5 are fitted and fixed to the rotary shaft 9. The rotating shaft 9 is rotatably supported inside the housing 8.

  The outer ring 3 and the both inner rings 5 and 5 constituting such a double-row angular ball bearing 1 are described in, for example, Patent Documents 1 to 5, etc., forging, rolling, cutting or cutting. By grinding, it is processed into a predetermined shape and size. For example, the outer ring 3 has been conventionally manufactured by a process as shown in FIG. First, the conventional method for manufacturing a bearing outer ring will be described.

In the conventionally known method for manufacturing a bearing outer ring shown in FIG. 9, first, a cylindrical material 10 as shown in (A) is cut into a predetermined length from a long raw material. obtain.
Next, the material 10 is subjected to upsetting by crushing in the axial direction between the pressing surfaces facing each other in a pair of molds, so that the outer peripheral surface is a convex arc surface as shown in FIG. The first intermediate material 11 is
Next, the second intermediate material 12 shown in (D) is obtained by subjecting the first intermediate material 11 to backward extrusion as shown in (C) → (D). In this backward extrusion process, the first intermediate material 11 is crushed in the axial direction between the die 13 and the punch 14, and the surplus material extruded along with the crushing is moved rearward in the pressing direction of the punch 14. Thus, the second intermediate material 12 including the disc-shaped bottom plate portion 15 and the cylindrical peripheral wall portion 16 is obtained.
Next, a punched cylindrical third intermediate material 17 as shown in (E) is obtained by performing a punching process for punching and removing the bottom plate portion 15 on the second intermediate material 12. This punching is performed by piercing the second intermediate material 12 with a punching punch using a plus processing machine.
After the third intermediate material 17 is made in this way, the third intermediate material 17 is cold rolled (CRF) to obtain a fourth intermediate material 18 as shown in FIG.
The fourth intermediate material 18 obtained in this way is subjected to necessary finishing such as cutting and polishing to form the outer ring raceways 2 and 2, as shown in FIG. 8 described above. Thus, the outer ring 3 constituting the double-row angular ball bearing 1 is completed.

  By the way, the said raw material 10 for making the said outer ring | wheel 3 uses the column-shaped thing produced by cut | disconnecting the elongate material with a circular cross section to the predetermined length rolled by the steel manufacturer. It has been conventionally known that the composition (cleanliness) of the columnar material 10 obtained in this way is not uniform, as described in Patent Document 6. That is, it is described in Patent Document 6 that nonmetallic inclusions are easily present in the central portion of the material 10 (a columnar portion closer to the center from the center to a radius of 40 to 50%) and the cleanliness is low. For example, it is conventionally known. When a metal material with low cleanliness is exposed to a portion where the rolling surfaces of the balls 3, 3 (FIG. 8) are in rolling contact among the outer ring raceways 2, 2 provided on the inner peripheral surface of the outer ring 3. In this part, it becomes difficult to ensure the rolling fatigue life.

  In consideration of these matters, it is preferable that the metal material present in the central portion of the material 10 is not exposed to at least the portion of the outer ring races 2 and 2 where the rolling contact surface is in rolling contact. . However, according to the conventional manufacturing method shown in FIG. 9 described above, the center-side metal material 20 existing at the center of the material 10 is formed on the outer ring raceway 3 of either of the outer ring raceways 3 and 3. It will be exposed to the surface, and it will be difficult to ensure the rolling fatigue life of the outer ring raceway 3.

  In view of such circumstances, Patent Documents 7 and 8 regulate the direction of plastic deformation when a cylindrical material is plastically deformed by forging to form an outer ring having a double row outer ring raceway on the inner peripheral surface. Thus, there is described an invention in which the thickness of the central metal material is reduced even if the central metal material is not exposed on the surfaces of both outer ring raceways or is exposed. That is, Patent Documents 7 and 8 describe an invention that regulates the direction of a plastic flow line indicating the direction in which the metal material constituting the outer ring is plastically deformed with respect to a cross section in a virtual plane including the central axis of the outer ring. Has been. Specifically, in the case of the invention described in Patent Document 7, with respect to the cross section, the starting point of the plastic flow line, that is, the intersection of the plastic flow line and the generatrix of the inner peripheral surface of the outer ring is determined. The outer ring is positioned at the center in the axial direction. At the same time, the angle between the plastic flow line and the tangent at the rolling contact portion of the outer ring raceway with the ball is regulated to 45 degrees or less. In the case of the invention described in Patent Document 8, the angle between the plastic flow line and the tangent at the rolling contact portion with the ball in the outer ring raceway is restricted to 0 to 30 degrees.

  According to the structure of the invention described in Patent Documents 7 and 8 as described above, the durability of the double row rolling bearing unit can be improved as compared with the conventional structure, but it is sufficient even when the use conditions become severe. There is room for improvement from the aspect of ensuring high durability. That is, there is a possibility that foreign matters such as water may be mixed in the grease which is a lubricant, a load applied during use becomes large, a rotation speed during use becomes fast, and the use conditions become severe, the above Patent Document 7, In the structure of the invention described in No. 8, there is a possibility that sufficient durability cannot always be secured. For example, in the case of the structure of the invention described in Patent Document 8, even if a clean metal material is exposed on the surface of one of the outer ring raceways, the surface of the other outer ring raceway is not necessarily clean. However, there is a possibility that the central metal material is exposed.

JP-A-9-176740 JP-A-9-280255 JP-A-11-140543 JP 2002-79347 A JP 2003-230927 A JP 2006-250317 A JP 2006-220195 A JP 2006-220221 A

  In view of the circumstances as described above, the present invention realizes a structure in which a clean metal material can be exposed on any of the double-row outer ring raceways provided on the inner peripheral surface of the outer ring, and incorporates the outer ring. It was invented to realize a structure capable of improving the durability of the double row rolling bearing unit.

The double row rolling bearing unit of the present invention includes a single outer ring, a pair of inner rings, and a plurality of rolling elements, like the conventional double row rolling bearing unit.
Of these, the outer ring is provided with double-row outer ring raceways on the inner peripheral surface. The outer ring was made by subjecting metal materials such as bearing steel, medium carbon steel, and high carbon steel to plastic working such as forging and turning such as turning and grinding. The outer peripheral surface is a cylindrical surface whose outer diameter does not substantially change in the axial direction, the inner peripheral surface has the smallest inner diameter in the axial middle portion, and both side portions of the axial middle portion are axially opposite ends. The shape is inclined in the direction in which the inner diameter gradually increases toward the part.
The inner rings have inner ring raceways on their outer peripheral surfaces.
The rolling elements are provided between the outer ring raceways and the inner ring raceways so that a plurality of rolling elements can roll freely in each row.

In particular, in the double-row rolling bearing unit of the present invention, the plastic flow lines indicating the direction in which the metal material constituting the outer ring is plastically deformed with respect to the cross section of the outer ring including the central axis of the outer ring are Do not cross any of the buses of the outer ring raceway.
When implementing such a double row rolling bearing unit of the present invention, preferably, the starting point of the plastic flow line exists between the double row outer ring raceways as in the invention described in claim 2. It exists in the axial direction intermediate part of a shoulder part. When the width dimension of the shoulder portion in the axial direction is W, the axial distance from the width direction center of the shoulder portion to the start point is set to W / 4 or less.

  According to the double-row rolling bearing unit of the present invention configured as described above, both outer ring raceways formed at two axially spaced positions sandwiching a portion of the inner peripheral surface having the smallest inner diameter. Of these, at least the portion where the rolling element load is applied does not need to expose the metal material near the center, which has a low degree of cleanliness among the materials. For this reason, the rolling fatigue life of the both outer ring raceways can be secured, and the degree of freedom in design for ensuring the durability of the double row rolling bearing including the bearing outer ring provided with these outer ring raceways can be improved.

  1 and 2 show an example of an embodiment of the present invention. The feature of the present invention is that the double-row outer ring raceway 2 provided on the inner peripheral surface of the outer ring 3 by regulating the direction of the plastic flow line indicating the direction in which the metal material constituting the outer ring 3 is plastically deformed. 2 is a portion less than 40% (more preferably less than 50%) of the radius from the center of the material 10 shown in FIG. 2 (A) and is inferior in cleanliness (disadvantageous from the viewpoint of ensuring durability). This is to prevent the center-side metallic material 20 (see FIGS. 2 and 3) from being exposed (which tends to have non-metallic inclusions having a large particle size). Since the structure and operation of the other parts are the same as those of the conventional structure shown in FIG. 8, the illustration and description of the equivalent parts are omitted or simplified, and the following description will focus on the characteristic parts of the present invention.

  FIG. 1 shows the so-called metal flow in which the metal material structure moves as the metal material is plastically deformed by forging. It is the figure represented by the cross section regarding the virtual plane to include. In FIG. 1, a plurality of curves (forging lines) i and i described inside the outer ring 3 represent the cross-sectional shape of the metal flow. That is, the outer ring 3 provided with the double-row outer ring raceways 2 and 2 on the inner peripheral surface shown in FIG. 1 is made of a columnar material 10 as shown in FIG. → (B) → (C) → (D) → (E) As shown in FIG. 1, by sequentially plastically deforming and further performing finishing and turning, which are finishing processes, To do.

  When the outer ring 3 is manufactured in this way, the metal material constituting the material 10 moves in the radial direction and the axial direction with plastic deformation. In other words, in the process of processing the material 10 into the outer ring 3 by forging, the metal material extruded from the radial center portion by crushing the radial center portion of the material 10 is radially outward and Move to the axial end. Along with this movement, the metal material is deformed in a complicated manner. That is, when it is assumed that a plurality of cylinders, each of which freely deforms in accordance with plastic deformation of the metal material, are present in the material 10, these cylinders are in the process of processing the material 10 into the outer ring 3. , Deform intricately. Each of the curves (a) and (b) represents the direction and degree of deformation, and the metal material constituting the material 10 moves toward the outer diameter side (upper side in FIG. 1) while the axial end (see FIG. 1). 1 represents a state of moving toward the left and right end portions of 1. In addition, in the middle part of each of the above curves A and B, the curve B connecting the portions that protrude most forward in the movement direction (outer diameter side or axial end side) (the ends of the curves A and A) is These are plastic flow lines indicating the direction in which the metal material undergoes plastic deformation. The metal material in the central portion of the material 10 moves most in the portion along the plastic flow line (curved line). 1 represent the rolling contact points (center points of the contact ellipses) between the outer ring raceways 2 and 2 and the rolling surfaces of the balls 6 and 6 (see FIG. 8). . The straight lines β and β are tangents related to the buses of the outer ring raceways 2 and 2 at the rolling contact points. The straight lines γ and γ are the normal lines (the direction of the contact angle related to the balls 6 and 6 above). ) Respectively.

  As described above, the metal material at the center of the material 10 is the center-side metal material 20 with poor cleanliness. Therefore, it is possible to prevent the center metal material (center side metal material 20) from reaching the two outer ring raceways 2 and 2 (when finishing is completed). This is necessary in terms of ensuring the durability of the row rolling bearing unit. For this reason, in the case of this example, the plastic flow line (curved line B) does not intersect with any of the buses of the outer ring raceways 2 and 2.

For this reason, in the case of this example, the processing conditions of the outer ring 3 are regulated so that the plastic flow line (curve B) satisfies the following two conditions.
First of all, the direction of the plastic flow line (curved line B) is directed to the outside in the radial direction as much as possible (the amount of inclination in the axial direction is reduced).
Second, the starting point O of the plastic flow line (curved line B) (the intersection of the plastic flow line and the generatrix of the inner peripheral surface of the outer ring 3) is the portion between the outer ring raceways 2 and 2; And it is located as close to the center as possible. Specifically, when the width dimension in the axial direction of the shoulder portion 21 existing between the outer ring raceways 2 and 2 is W, the width from the center in the width direction of the shoulder portion 21 to the start point O is described. The axial distance is suppressed to W / 4 or less.

  In the case of this example, by satisfying the above two conditions, the plastic flow lines (curved lines B) do not cross any of the buses of both the outer ring races 2 and 2 so that both the outer ring races 2 and 2 The metal material in the central portion is prevented from reaching the surface. For this reason, the rolling fatigue life of the both outer ring raceways 2 and 2 can be ensured, and the durability of the double row rolling bearing including the outer ring 3 provided with both the outer ring raceways 2 and 2 can be ensured.

With respect to the structure of the present example as described above, as shown in FIG. 4A, the ratio of the amount of inclination in the axial direction increases in the direction of the curve B ′, which is a plastic flow line (curve B ′). And the central axis of the outer ring 3 is reduced), the plastic flow line (curve B ′) intersects with the generatrix of any outer ring raceway 2. In such a case, the metal material (center side metal material 20) at the center of the material 10 reaches the surface of any one of the outer ring raceways 2.
Further, as shown in FIG. 4B, even when the starting point of the curve b, which is a plastic flow line, deviates from the shoulder 21, the surface of either or both outer ring raceways 2 is The center side metal material 20 will reach.
Further, in the case of the structure described in any of FIGS. 4A and 4B, it is impossible to sufficiently ensure the durability of the double row rolling bearing.

  In addition, although it does not ask | require in particular about the processing method of the said outer ring | wheel 3 which can make a plastic flow line (curve (b)) into a shape as shown in FIG. 1, it can process in the process as shown, for example in FIG. That is, as shown in FIG. 2 (A), a metal columnar material 10 that can be quenched and hardened after plastic working, such as an iron-based alloy such as medium carbon steel, bearing steel, and carburized steel, is sequentially added. Perform plastic working or punching. Then, after passing through the first intermediate material 11a shown in (B), the second intermediate material 12a shown in (C), and the third intermediate material 17a shown in (D), the fourth intermediate material shown in (E). 18a is obtained. Further, the fourth intermediate material 18a is subjected to necessary cutting and grinding to form the outer ring 3 constituting the double-row angular ball bearing 1 as shown in FIG. Hereinafter, the process of processing the material 10 into the fourth intermediate material 18a will be described in order. Of the following processes, the upsetting process, the front-rear extrusion process, and the punching process shown in (A) → (D) are basically performed hot or warm. The rolling process shown in D) → (E) is performed in a cold manner. However, if a small outer ring 3 is formed and a metal material having excellent ductility is used, the entire process is performed if possible. You may go cold.

First, in the upsetting process, as shown in FIG. 2 (A) → (B), the outer diameter is expanded while the material 10 is crushed in the axial direction, and the intermediate portion in the axial direction swells. The first intermediate material 11a is used. The basic implementation status of such an upsetting process is the same as the upsetting process in the conventional manufacturing method shown in FIG.
In the case of this example, the first intermediate material 11a shown in FIG. 2B is processed into the second intermediate material 12a shown in FIG. Thus, in the front-rear extrusion process for processing the first intermediate material 11a into the second intermediate material 12a, a die having an inner surface shape that matches the surface shape of the second intermediate material 12a and a punch having an outer surface shape are used. use. Among these, the inner surface shape of the die is a bottomed cylindrical shape as shown in the shape of the second intermediate material 12a shown in FIG. The circular convex part which has the height dimension of is provided. A space between the outer peripheral surface and the inner peripheral surface of the circular convex portion is a cylindrical molding space for forming the lower portion of the second intermediate material 12a. The punch is pushed into the upper portion of the second intermediate material 12a to process the inner surface shape and upper end surface of the upper portion, and the tip of the punch is formed from the inner diameter of the die. Also have a small outer diameter.

In order to obtain the shape of the plastic flow line as shown in FIG. 1, the diameter of the tip of the punch and the tip of the circular convex portion of the die is the center side metal of the first intermediate material 11a. It is preferable that the material 20 is larger than the diameter of the part exposed to the both axial end surfaces of the first intermediate material 11a.
Similarly, in order to obtain the shape of the plastic flow line, when the punch has a structure in which the tip portion and a large-diameter portion having a larger diameter than the tip portion are continuous by a step portion, the tip It is preferable that the length from the end face of the portion to the stepped portion is substantially the same as the height of the circular convex portion of the die.

  In order to process the first intermediate material 11a into the second intermediate material 12a by the front-rear extrusion process, the first intermediate material 11a is placed in the die on one side surface (lower surface) of the first intermediate material 11a. ) Is set in a state in which it is brought into contact with (places) the circular convex portion. Next, the punch is pressed strongly against the central portion of the other surface in the axial direction of the first intermediate material 11a, and between the tip surface (lower surface) of the punch and the tip surface (upper surface) of the circular convex portion, Crush the middle part of one intermediate material in the axial direction. Then, the metal material pushed out in the radial direction along with the crushing is pushed into the cylindrical forming space and the punch together with the metal material present in the radially outward portion of the first intermediate material 11a. It moves to the cylindrical space which exists between the outer peripheral surface of this punch and the inner peripheral surface of the said die behind in the direction. And it is set as the said 2nd intermediate raw material 12a which provided the partition part 23 in the axial direction intermediate part internal diameter side of the cylindrical part 22 as shown to (C) of FIG.

In order to facilitate the removal of the second intermediate material 12a from the die, the die can be moved up and down, and the first die for processing the inner surface shape of the lower portion of the second intermediate material 12a. It is preferable that the second intermediate material 12a and the second die for processing the lower end surface of the second intermediate material 12a are separably combined.
In addition, the first intermediate material 11a can be processed into the second intermediate material 12a by performing the extrusion process in two stages in addition to the front / rear extrusion process, or the front extrusion process and the rear process. It can also be carried out by performing extrusion in two stages before and after. Which method is adopted is selected in consideration of the direction of the plastic flow line obtained, the capacity of the press machine that can be used, and the like.

  In any case, after the second intermediate material 12a as described above is taken out from the die, the same punching and rolling processes as those in the conventional manufacturing method described above are performed, so that (D ) Through the third intermediate material 17a shown in FIG. 2E and the fourth intermediate material 18a as shown in FIG. In the punching process, a punching punch (not shown) is pushed into the inner diameter side of the second intermediate material 12a while the second intermediate material 12a is held on the inner peripheral surface of the receiving die (not shown), and the partition wall 23 is moved. Remove by punching. By such a punching process, the third intermediate material 17a is formed, as shown in FIG. 2D, in which the inner diameter of the central portion in the axial direction is smaller than the inner diameter of the portions near both ends. Next, in the rolling process, the inner and outer peripheral surfaces of the third intermediate material 17a are plastically deformed into a shape corresponding to the peripheral surfaces of both rollers by a pair of rollers (not shown) to obtain the fourth intermediate material 18a.

  The fourth intermediate material 18a is thicker than the completed outer ring 3 {see FIG. 2E and the chain line in FIG. 3}. Therefore, the fourth intermediate material 18a is subjected to predetermined cutting (turning) processing and grinding processing to complete the outer ring 3. 2A to 2E show changes in the distribution state of the center-side metallic material 20 as the processing progresses. The boundary line between the center side metal material 20 and the clean metal material present in the periphery corresponds to either the curve (forging line) a or b shown in FIG. 2E and FIG. 3, the distribution state of the central metal material 20 and the cross-sectional shape of the outer ring 3 after completion at the stage of the fourth intermediate material 18a are indicated by chain lines. . As is apparent from the cross-sectional shape of the outer ring 3 represented by the chain line and the boundary line, a plastic flow line indicating the direction in which the metal material is plastically deformed is formed on the inner peripheral surface of the outer ring 3. There is no crossing with the buses of the double row outer ring raceways 2 and 2. Further, the starting point of the plastic flow line is located substantially at the center of the shoulder portion 21 provided between the outer ring raceways 2 and 2.

  As is clear from FIG. 2E and FIG. 3, the plastic flow line is not crossed with the buses of the outer ring races 2 and 2, and the starting point of the plastic flow line is set to the both outer ring races. 2 and 2, if it is positioned substantially at the center of the shoulder portion 21 provided between the two, the outer ring raceways 2, 2 are provided with a highly clean metallic material (from the center of the material 10, from the center). The portion having a radius of 40 to 70%, more preferably the portion having a radius from the center of 50 to 70%) is exposed. For this reason, the rolling fatigue life of both the outer ring raceways 2 and 2 is ensured, and the degree of freedom in design for ensuring the durability of the wheel bearing rolling bearing unit including the outer ring 3 provided with the both outer ring raceways 2 and 2 is improved. Can be planned.

The result of the simulation performed to confirm the effect of the present invention will be described. In this simulation, with respect to the cross section of the outer ring 3 shown in FIG. 1, the difference in the direction of the plastic flow line (curved line B) and the starting position is that of the double row outer ring raceways 2 and 2 formed on the inner peripheral surface of the outer ring. The influence on the maximum diameter of non-metallic inclusions expected to appear on the surface was determined by the extreme value statistical method. Incidentally, as the maximum diameter of nonmetallic inclusions appearing on the surface of the outer ring raceways 2,2 are large, possible to secure the rolling fatigue life of these two outer ring raceways 2, 2 (e.g., L ₁₀ life) becomes difficult. In other words, the smaller the diameter of the non-metallic inclusions appearing on the surface portions of these outer ring raceways 2 and 2, the better.

First, Table 1 below shows that the direction of the plastic flow line (curve b) is the maximum diameter of non-metallic inclusions appearing on the surfaces of the outer ring raceways 2 and 2 and the rolling of the outer ring raceways 2 and 2. It is shown in regard to fatigue life (L ₁₀ life) to exert influence the obtained results. In Table 1, the symbol “◯” indicates that the plastic flow line intersects with at least one of the outer ring raceways 2 and 2, and the symbol “×” indicates that neither of the buses intersects. Respectively. In addition, the numerical values described in the columns of the raceway surfaces 1 and 2 represent the maximum diameter (μm) of the nonmetallic inclusion that is expected to appear on the surface of the outer ring raceway 2. Also, the unit of L ₁₀ life is time. In Table 1, (1) to (3) are comparative examples that are out of the technical scope of the present invention, and (4) to (7) are examples of the present invention.

  As is clear from Table 1 above, according to the structure in which the plastic flow line does not intersect with the buses of any of the outer ring raceways 2 and 2, the maximum diameter of the non-metallic inclusions appearing on the surfaces of these outer ring raceways 2 and 2 The rolling fatigue life of these outer ring raceways 2 and 2 can be secured. On the other hand, when the plastic flow line intersects with the bus bar of any outer ring raceway 2, the maximum diameter of the non-metallic inclusions appearing on the surface of the outer ring raceway 2 is increased. For example, when water is mixed in the grease for lubrication, the durability of the double row rolling bearing unit cannot be ensured.

  Next, Table 2 below shows the result of the extreme value statistical survey on the influence of the starting point position of the plastic flow line on the maximum diameter of the nonmetallic inclusions appearing on the surfaces of the outer ring raceways 2 and 2. It shows about. In Table 2, (1) to (3) are structures corresponding to the invention described in claim 2, and (4) and (5) are from the invention described in claim 2. Indicates the disengaged structure. FIG. 5 shows specific positions of the starting points (1) to (5).

From Table 2 as described above, the starting point of the plastic flow line is present in the middle portion in the axial direction of the shoulder portion 21 existing between the double-row outer ring raceways 2 and 2, and the axial direction of the shoulder portion 21 is related. When the width dimension is W, the axial distance from the center in the width direction of the shoulder 21 to the start point is preferably 0.4 W or less, more preferably W / 4 (0.25 W) or less. I understand.
As is apparent from the simulations showing the respective results in Tables 1 and 2, the direction of the plastic flow line is restricted to a direction that does not intersect any of the outer ring raceways 2 and 2, and the starting point position of the plastic flow line Is restricted to a portion closer to the center of the shoulder portion 21, the maximum diameter of the non-metallic inclusions appearing on the surfaces of the outer ring raceways 2 and 2 can be kept small, resulting in a defect caused by moisture mixed into the grease. It is possible to prevent premature delamination starting from non-metallic inclusions under lubrication and sufficiently ensure the durability of the double row rolling bearing.

  Next, various outer rings 3 for constructing the double-row angular ball bearing 1 as shown in FIG. 8 described above are produced by changing the processing conditions, and the outer ring raceway 2 provided on the inner peripheral surface of each outer ring 3. The results of tests on durability 2 will be described. The double row angular contact ball bearing had an inner diameter of 40 mm, an outer diameter of 74 mm, a width of 39 mm, and a working point distance (distance between the intersections of the line representing the contact angle of the ball in each row and the central axis) of 57 mm. Among the constituent members of such a double-row angular ball bearing, the pair of inner rings 5 and 5 were made by the method described in paragraphs [0015] and [0016] of the specification of Patent Document 8 described above. The manufacturing method of the inner rings 5 and 5 is not a feature of the present invention and is described in detail in the above-mentioned Patent Document 8, and thus detailed description thereof is omitted.

  The outer ring 3 was manufactured by the method shown in FIG. Specifically, as the columnar material 10 shown in FIG. 2A, a high carbon chromium bearing steel type 2 (SUJ2) having a diameter of 40 mm and an axial dimension of 40 mm was prepared. Next, the above-mentioned material 10 heated to 1100 to 1200 ° C. is subjected to upsetting by crushing it in the axial direction (vertical direction) with a 24500 kN (2500 Ton · f) press machine until the axial dimension becomes 30 mm. It was set as the 1st intermediate material 11a shown to 2 (B). Next, the first intermediate material 11a is forged as described above to form the second intermediate material 12a as shown in FIG. 2C, and then the partition wall portion 23 is punched to obtain the ( A third intermediate material 17a as shown in FIG. Further, the third intermediate material 17a is cold-rolled to form the original part of the outer ring raceways 2 and 2 on the inner peripheral surface, and the inner diameter of each part including both ends is set to a predetermined dimension. After finishing the fourth intermediate material 18a shown in FIG. 2E, the fourth intermediate material 18a was turned to form the outer ring 3. Next, the outer ring 3 was heated to 840 ° C., held for 1 hour, and then quenched, and then subjected to tempering treatment at 180 ° C. × 2 hours, and the surface hardness of the outer ring 3 was set to HRC61. Next, the outer ring 3 was ground to improve the dimensional accuracy of each part of the outer ring 3 including both the outer ring raceways 2 and 2.

As in the case of the invention described in Patent Document 8, the outer ring 3 obtained in this way is divided into two at the intermediate portion in the axial direction, and the inner peripheral surface as shown in FIG. A semi-outer ring 25 having a single-row outer ring raceway 2 is combined, and the semi-outer ring 25 and the inner ring 5 are combined to form a single-row angular ball bearing unit 26 as shown in FIG. Then, the durability (L ₁₀ life) of the semi-outer ring 25 constituting the ball bearing unit 26 is measured by a measuring method as shown in FIG. 6 as in the case of the invention described in Patent Document 8. The relationship between the measurement results, the direction of the plastic flow line {whether or not to cross (contact) the bus of the outer ring raceway 2}, and the starting point was organized.

In order to measure the durability, first, the ball bearing unit 26 is placed in the container 28 with the inner ring 5 attached to the rotating shaft 27. In this container 28, a liquid 29 in which 5% by mass of water is mixed with lubricating oil (VG 10) is stored, and the entire ball bearing unit 26 is immersed in the liquid 29. Next, the inner ring 5 was rotated at 1000 min ⁻¹ while applying an axial load of 8820 N by the rotary shaft 27, and the vibration generated in the ball bearing unit 26 was continuously measured with a vibration meter. When the measured value of vibration (vibration at a frequency considered to be caused by damage to the outer ring raceway 2) caused by the separation of the outer ring raceway 2 on the inner peripheral surface of the semi-outer ring 25 exceeds a certain value, the rotation is performed. The shaft 27 was stopped, the time from the start of rotation to the stop was recorded, and this time was defined as the life of the ball bearing unit 26 based on the damage of the outer ring raceway 2. Further, the extracted semi-outer ring 25 was cut in the radial direction and the cross section thereof was observed to determine the direction and starting point of the plastic flow line. Ten such measurements were made for each sample of the same type (made by the same manufacturing method), and the L ₁₀ life was examined. The results are shown in Table 3 below. In Table 3, the value of the maximum diameter of the inclusion was determined by extreme value statistics based on the direction of the plastic flow line and the starting point position.

The measurement results shown in Table 3 are shown in FIG. In FIG. 7, the horizontal axis indicates the starting point position of the plastic flow line, the vertical axis indicates the L ₁₀ life, and the symbol “▲” indicates the plastic flow line and the generatrix of the outer ring raceway 2 with respect to the direction of the plastic flow line. The symbol “●” indicates that they are not in contact (contact), and that they are in contact with each other. As can be seen from the description in Table 3 and FIG. 7, the starting point of the plastic flow line is set near the center of the shoulder 21, and the plastic flow line and the bus of the outer ring raceway 2 are crossed. If not, sufficient durability can be obtained by securing a rolling fatigue life even under severe lubricating conditions such as when water is mixed in the lubricating oil.

  That is, if the starting position of the plastic flow line is equal to or less than ¼ of the width W of the shoulder portion 21 from the central position of the shoulder portion 21, the maximum diameter of the nonmetallic inclusion appearing on the surface of the outer ring raceway 2 Is reduced, and the rolling fatigue life of the outer ring raceway 2 is extended. On the other hand, when the starting position of the plastic flow line exceeds 1/4 of the width W, or when the plastic flow line comes into contact with the bus of the outer ring raceway 2, it appears on the surface of the outer ring raceway 2. The maximum diameter of the non-metallic inclusion is increased, and as a result, the rolling fatigue life of the outer ring raceway 2 is shortened.

The fragmentary sectional view for demonstrating the plastic flow line which shows the direction in which the metal material which comprises the outer ring | wheel incorporated in the double row rolling bearing unit of this invention deforms plastically. Sectional drawing which shows one example of the manufacturing method for obtaining a preferable plastic flow line in order of a process. Sectional drawing which shows a 4th intermediate material. The fragmentary sectional view which shows two examples of the unpreferable plastic flow line. The schematic diagram for demonstrating the starting position of a plastic flow line. Sectional drawing which shows the implementation condition of the durability test done in order to confirm the effect of this invention. The graph which shows the result of this durability test. Sectional drawing which shows an example of the rotation support part provided with the angular type double row ball bearing provided with the bearing outer ring used as the object of the manufacturing method of this invention. The figure similar to FIG. 1 which shows the manufacturing method of the bearing outer ring | wheel conventionally known.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Double row angular contact ball bearing 2 Outer ring raceway 3 Outer ring 4 Inner ring raceway 5 Inner ring 6 Ball 7 Cage 8 Housing 9 Rotating shaft 10 Material 11, 11a First intermediate material 12, 12a Second intermediate material 13 Die 14 Punch 15 Bottom plate 16 Peripheral wall parts 17, 17a Third intermediate material 18, 18a Fourth intermediate material 20 Center side metal material 21 Shoulder part 22 Cylindrical part 23 Partition part 25 Semi-outer ring 26 Ball bearing unit 27 Rotating shaft 28 Container 29 Liquid

Claims (2)

  A single outer ring having a double row outer ring raceway on the inner peripheral surface, a pair of inner rings having inner ring raceways on each outer peripheral surface, and each row between these outer ring raceways and both inner ring raceways. A plurality of rolling elements each provided so as to be freely rollable, and the outer ring is formed by subjecting a metal material to plastic working and shaving, and the outer peripheral surface has an outer diameter in the axial direction. Is a cylindrical surface that does not substantially change, and the inner peripheral surface has the smallest inner diameter in the axial intermediate portion, and the inner diameter gradually increases as both side portions of the axial intermediate portion move toward both axial end portions. In the double-row rolling bearing unit having an inclined shape, with respect to a cross section in a virtual plane including the central axis of the outer ring, the plastic flow lines indicating the direction in which the metal material constituting the outer ring is plastically deformed are the two outer rings. Characterized by not crossing any of the buses of the orbit Double row rolling bearing unit that.   The starting point of the plastic flow line exists in the axially intermediate portion of the shoulder portion existing between the double row outer ring raceways, and when the width dimension in the axial direction of the shoulder portion is W, this shoulder The double row rolling bearing unit according to claim 1, wherein an axial distance from a center in a width direction of the portion to the start point is W / 4 or less.

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