JP4743176B2 - Combination ball bearings and double row ball bearings - Google Patents

Description

  The present invention includes, for example, combination ball bearings used in industrial machines, robot joints and turning mechanisms, rotary tables and spindle turning mechanisms in machine tools, medical equipment, semiconductor / liquid crystal manufacturing devices, optical and optoelectronic devices, etc. The present invention relates to a double-row ball bearing, and more particularly, to a ball bearing used for an application in which a radial load and an axial load in both directions, particularly a large moment load is applied as a load.

  Usually, in a ball bearing, such as a deep groove ball bearing, as shown in FIG. 21, the ball 3 is rotatably held between the raceway surfaces of the inner ring 2 and the outer ring 1 to hold sealed grease and prevent leakage to the outside. Or the seal | sticker 5 is mounted | worn on the axial direction end surface between the inner ring | wheel 2 and the outer ring | wheel 1 in order to prevent the foreign material penetration | invasion from the exterior to the inside of a bearing. Further, as the ball guide holder 4 for holding the ball 3, as shown in FIG. 22, a crown-shaped (cantilever ring structure) ball guide synthetic resin holder in which a required number of pocket portions 6b are formed in the ring portion 6a. Is adopted as standard.

As shown in FIG. 22, the ball guide holder 4 normally has a pocket inner surface 6 c that holds the ball 3 formed in a spherical shape having a curvature slightly larger than the curvature of the ball 3. As shown in FIG. 23, the movement amount in the radial direction is determined by the smaller one of the clearance ΔR ₁ between the ball 3 and the pocket inner diameter side end surface or the clearance ΔR ₂ between the ball 3 and the pocket outer diameter side end surface. The
Further, as shown in FIG. 24, the amount of movement of the cage 4 in the axial direction is determined by the clearance ΔS ₁ between the ring-side pocket inner surface 6c and the ball 3 in one direction, and the other direction is determined by the pocket column portion 6d. The ball is positioned by a clearance ΔS ₂ between the ball locking portion 6 e formed at the tip and the ball 3.

The cage 4 is usually manufactured by injection molding. However, when the cage is separated from the mold, the cage 4 is separated in the axial direction (so-called axial draw type). At this time, since the relationship between the inner diameter φd _{P of the} pocket surface and the distance between the pair of ball locking portions 6e, that is, the diameter H of the mouth diameter is φd _P > H, the ball locking portion 6e forms a pocket at the time of release. When the molding die member (spherical member) passes through, deformation occurs. You have to take the so-called unreasonable form.

Therefore, it is necessary for the ball engaging portion 6e to maintain flexibility so as not to leave a breakage, a crack, or a large plastic deformation that causes a functional problem when releasing.
In addition, the ball locking portion 6e has _a relationship that the ball diameter φD _a with respect to the outer diameter H between the opposing ball locking portions 6e is φD _a > H. When inserting into the pocket portion 6b, it is necessary that the ball locking portion 6e is not damaged or chipped even when passing between the ball locking portions 6e. The structure is such that it cannot be removed from the ball 3.

Under normal general rotation conditions, the cage 4 is unlikely to come out of the ball 3, but due to conditions such as large vibration during bearing rotation or inclination between the outer ring 1 and the inner ring 2 due to moment load or other factors. In an application in which an offset load is applied to the ball locking portion 6e of the cage 4, it is easy to come off, so it is necessary to maintain the strength to prevent the cage 4 from falling off (disconnecting) in the axial direction.
If the balls 3 are removed in the axial direction in at least some of the pocket portions 6b, adjacent balls in the circumferential direction come into contact with each other, and heat generation or wear occurs due to sliding contact between the balls. Leads to seizure and ball damage. The cage 4 also suffers from problems such as wear and chipping due to the uneven contact of the drop-off portion.

In the above-described applications, in order to satisfy the conflicting requirements of both, selection of an appropriate cage resin material, selection of the content of a reinforcing material such as glass fiber, and the optimum diameter of the ball locking portion 6e Several problems need to be solved before the final specification design is established, such as the selection of the dimension H.
On the other hand, in the case of an angular ball bearing, as shown in FIG. 25 and FIG. 26, a so-called rice bran cage 7 having a double-sided ring structure is generally used. In the case of a narrow ball bearing, a ball guide cage having a crown-shaped cantilever ring structure has been proposed as a measure for further reducing the axial width of the ball bearing.
JP 2004-333588 A (first page, FIG. 1)

However, in the narrow angular contact ball bearing disclosed in Patent Document 1, the ball diameter has to be reduced especially for the purpose of reducing the axial width of the bearing for the purpose of space saving in the axial direction. Since the cross-sectional thickness of the cage is thin, the annular strength of the ring portion is reduced, and the cage is easily deformed, there is an unsolved problem that the cage is easily pulled out in the axial direction described above.
In particular, in the applications described above, there are many cases in which operation is performed with a large moment load acting as a load, and there is a difference in the revolution speed of each ball due to the variation in the load load of each ball, resulting in an unbalanced load on the cage. There is a concern that the cage may be deformed and the cage may come off in the axial direction due to a load applied to the ball locking portion. If the cage strength is extremely increased, as described above, the locking portion may be damaged or cracked due to deformation load when the ball passes through the locking portion when releasing from the mold or when the cage is incorporated. Occurrence and plastic deformation will occur.

  Therefore, the present invention has been made paying attention to the above-mentioned unsolved problems of the conventional example, and when a crown-shaped cage is adopted for the purpose of space saving in the axial direction, the axial displacement of the cage is prevented. It is an object of the present invention to provide a ball bearing that is not generated, and that can exhibit stable rotational performance without damaging or damaging the ball and damaging the cage.

  In order to achieve the above object, a combination ball bearing according to claim 1 is configured by combining two rows of narrow ball bearings, and each narrow ball bearing has a ring portion on one side, and the other of the ring portions. A combined ball bearing in which a ring-shaped ball guide retainer having a required number of pocket portions for holding balls on its side is arranged on the combined surface side, and the pocket portion is the ring portion. A ball locking portion that prevents the ball from being pulled out formed on the tip portion opposite to the tip portion of the pocket portion with respect to the axial distance between the center of curvature of the pocket portion and the tip of the ball locking portion. The value obtained by adding the axial clearance between the pocket surface of the pocket portion and the ball to the axial clearance between the end portions of the two opposing cages in a state where the center of curvature coincides with the center of curvature of the ball is small. It is characterized by being set to be.

In addition, the combined ball bearing according to claim 2 is characterized in that, in the invention according to claim 1, the ball guide retainer is formed of a synthetic resin material.
Further, the combined ball bearing according to claim 3 is the invention according to claim 1 or 2, wherein each of the narrow ball bearings is in the axial direction of the inner and outer rings on the ring portion side and the ball on the opposite side through the ball. An annular seal body is disposed on the end surface portion.

Furthermore, the combined ball bearing according to claim 4 is characterized in that, in the invention according to claim 3, the annular seal body is in contact with at least one of the outer ring and the inner ring of the narrow ball bearing.
Still further, the double row ball bearing according to claim 5 has a configuration of a narrow double row ball bearing, and each row has a ring portion on one side and a ball on the other side of the ring portion. A double-row ball bearing in which a crown-shaped ball guide cage formed with a required number of pocket portions to be held is arranged with the ring portion side facing the inner side in the axial direction of the bearing,
The pocket portion has a ball locking portion that prevents a ball formed at a tip portion on the opposite side to the ring portion, and an axial distance between the center of curvature of the pocket portion and the tip of the ball locking portion. In contrast, the axial clearance between the pocket surface of the pocket portion and the ball in the axial clearance between the ring portion end portions of the two opposing cages in a state in which the center of curvature of the pocket portion and the center of curvature of the ball coincide with each other. The feature is that the value obtained by adding the direction clearance is set to be small.

A double row ball bearing according to claim 6 is characterized in that, in the invention according to claim 5, the ball guide retainer is formed of a synthetic resin material.
Further, the double-row ball bearing according to claim 7 is the invention according to claim 5 or 6, wherein the double-row ball bearing is in the inner and outer ring axial directions on the ring portion side and the ball on the opposite side through the ball. An annular seal body is disposed on the end surface portion.

  Furthermore, the double-row ball bearing according to claim 8 is characterized in that, in the invention according to claim 7, the annular seal body is in contact with at least one of the outer ring and the inner ring of the narrow ball bearing.

  According to the present invention, in a combination bearing in which two rows of narrow ball bearings are combined, or in a double row ball bearing with narrow width, with respect to the axial distance between the center of curvature of the pocket portion and the tip of the ball locking portion, The axial clearance between the pocket surface of the pocket portion and the ball is added to the axial clearance between the ring portion end portions of the two opposing cages in a state where the center of curvature of the pocket portion and the center of curvature of the ball are matched. When the cage moves in the axial direction due to inner / outer ring inclination due to moment load, the larger diameter of the ball comes into contact with the cage end surface of the other combined bearing. Since the portion does not slip until the portion exceeds the ball locking portion, an effect that the ball and the cage can be reliably prevented from falling off is obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an essential part showing a state in which two single-row ball bearings according to the first embodiment of the present invention are combined. FIG. 2 is a cross-sectional dimension ratio (B / H) and deformation of inner and outer rings in the radial direction. FIG. 3 is a graph showing the relationship between the sectional dimension ratio (B / H) and the sectional secondary moment I, and FIG. 4 is an explanatory diagram for explaining the amount of deformation in the radial direction of the inner ring. FIG. 5, FIG. 5 is an explanatory diagram for explaining a method for calculating the cross-sectional secondary moment of the inner ring, and FIG. 6 is a graph showing the relationship between the cross-sectional dimension ratio (B / H) and the deformation amount of the inner and outer rings in the radial direction. FIG. 7 is a graph showing the relationship between the cross-sectional dimension ratio (B / H) and the secondary moment I of cross section, FIG. 8 is a graph showing a comparison of moment rigidity between the product of the present invention and a conventional cross roller bearing, and FIG. Is a graph showing a comparison of calculated moment stiffness in various bearings, FIG. 10 is a cross-sectional view showing a ball guide cage 11 is a partial perspective view of the cage viewed from the inside in the radial direction, FIG. 12 is an arrow view viewed from the direction of the arrow Y in FIG. 10, FIG. 13 is a sectional view taken along the line ZZ in FIG. FIG. 15 is a view showing a cage, (a) is a view as seen from the direction of arrow X in FIG. 10, and (b) a modified example thereof. (C) is an enlarged view showing a modified example of the cage shown in (b), (d) is a diagram showing an interference state of the cage, and (e) is an interference avoidance state of the cage. FIG.

As shown in FIG. 1, the combination bearing 100 of the present invention has a configuration in which two single-row angular ball bearings 100A and 100B are combined in two rows on the back so that the contact angle represents a square shape.
Here, in each of the single row angular ball bearings 100A and 100B, as shown in FIG. 1, a large number of balls 103 are rotatably arranged between the raceway groove 101a of the outer ring 101 and the raceway groove 102a of the inner ring 102. It has the structure of a narrow bearing.

In addition, the material of the inner ring 102, the outer ring 101, and the ball 103 is a bearing steel (for example, SUJ2, SUJ3, etc.) under standard use conditions, but depending on the use environment, a stainless steel material (for example, a corrosion resistant material) Martensitic stainless steel materials such as SUS440C, austenitic stainless steel materials such as SUS304, precipitation hardening stainless steel materials such as SUS630), titanium alloys and ceramic materials (for example, Si ₃ N ₄ , SiC, Al ₂ O ₃ , ZrO) ₂ etc.) may be adopted.

The lubrication method is not particularly limited, and mineral oil-based grease or synthetic oil-based grease (for example, lithium-based or urea-based grease) or oil can be used in a general use environment, and fluorine-based grease or fluorine in high-temperature environment applications. Series lubricants or solid lubricants such as fluororesin and MoS ₂ can be used.
Narrow bearings are sizes not applicable to standard angular contact ball bearings (78XX, 79XX, 70XX, 72XX, 73XX series, etc.) defined by the International Organization for Standardization (ISO). The sectional dimension ratio (B / H) between the axial sectional width B and the radial sectional height H (= (outer ring outer diameter D−inner ring inner diameter d) / 2) is (B / H) < The bearing is 0.63.

A narrow double-row ball bearing has a cross-sectional dimension ratio (B2 / H2) of an axial cross-sectional width B2 and a radial cross-sectional height H2 (= (outer ring outer diameter D2-inner ring inner diameter d2) / 2). B2 / H2) A narrow double row angular high ball bearing with <1.2.
For example, in the case of 7208A (angular ball bearing with a contact angle of 30 degrees) as a conventional ball bearing, the inner ring inner diameter φ40 mm, the outer ring outer diameter φ80 mm, and the axial sectional width (bearing unit width) B is 18 mm. (B / H) = 0.9.

  Therefore, in the angular ball bearings 100A and 100B of the present embodiment, the sectional dimension ratio (B / H) = 0.45 (the inner ring inner diameter and the outer ring outer diameter remain the same, and the axial sectional width (bearing single body width) is 9 mm. ). As a result, radial load, axial load in both directions, and moment load can be received, space saving of 1/2 in the axial dimension can be achieved, and the single row 7208A can be replaced, and torque can be reduced. High rigidity can be achieved.

Of course, if necessary, the cross-sectional dimension ratio (B / H) of the angular ball bearing 100 may be set to be less than 0.45 or more than 0.45 (where (B / H) <0.63). Absent.
Thus, the reason why B / H <0.63 is as follows.
2 and 3 are standard thin ball bearings (bearing inner diameter: φ38.1 mm, bearing outer diameter: φ47.625 mm, bearing width: 4.762 mm, cross-sectional dimension ratio (B / H)). = 1) as a reference, the inner and outer ring rings are deformed in the radial direction when the bearing inner diameter is changed without changing the bearing outer diameter and bearing width (that is, when the value of (B / H) is changed). properties (see Fig. 4: an inner ring of illustration) and radial cross-sectional secondary moment I: shows the result of comparison (see FIG. 5 calculated as I = bh ^3/12).

  6 and 7 are also used as standard thin ball bearings (bearing inner diameter: φ63.5 mm, bearing outer diameter: φ76.2 mm, bearing width: 6.35 mm, cross-sectional dimension ratio (B / H) = 1) as a reference, the radius of the inner and outer ring rings when the bearing inner diameter is changed without changing the bearing outer diameter and bearing width (that is, when the value of (B / H) is changed) The result of having compared the deformation characteristic of a direction and the cross-sectional secondary moment I of the radial direction is shown.

In any of the bearings, (B / H) = 0.63, and the change in the rigidity increase rate gradient is remarkable. That is, the increase in the secondary moment I of the cross section becomes significant, and the decrease in the deformation amount of the inner and outer ring in the radial direction becomes saturated.
Therefore, in this embodiment, it is possible to prevent bearing deformation due to lathe processing during inner / outer ring production or processing force during polishing processing, which is a problem with conventional ultra-thin bearings, and bearing accuracy such as roundness and uneven thickness Can be improved.

Deformation of inner and outer rings when bearings are fixed with inner ring retainers and outer ring retainers (especially when they are assembled with a clearance fit with the shaft or housing). In addition, it is possible to prevent torque defects and rotational accuracy defects caused by deformation, or problems such as increased heat generation, wear and seizure.
Single-row ball bearings are difficult to apply preload or moment load in one row, but by combining multiple rows of two or more rows, radial load, axial load and moment load can be applied. It becomes possible to do.

Further, since each ball always contacts the inner and outer raceway grooves at two points, an increase in torque due to a large spin of the ball can be suppressed as in a four-point contact ball bearing. Since the rolling resistance is lower than that of the bearing, a reduction in torque can be realized.
FIG. 8 is a comparison data of the relative inclination angle of the inner and outer rings when a moment load is applied to each bearing of the single-row product of the present invention (two-row rear combined bearing with a contact angle of C-shape) and the cross roller bearing. It is.

Here, the main dimensions of the measuring bearing are
Invention product:
Inner ring inner diameter: φ170
Outer ring outer diameter: φ215
Single unit width: 13.5mm
Rolling element pitch circle diameter: φ192.5
Contact angle 35 °
(B / H = 0.60)
Cross roller bearing:
Inner ring inner diameter: φ130
Outer ring outer diameter: φ230
Assembly width: 30mm
Rolling element pitch circle diameter: φ189.7
It is.

As is apparent from FIG. 8, for both the present invention product and the cross roller bearing in which the pitch circle diameters of the rolling elements are substantially the same, the comparison data of the moment stiffness is about the present invention product about the cross roller bearing. It was confirmed that the moment rigidity was maintained 1.3 times.
In addition to the above experiments, the product of the present invention and the cross roller bearing were assembled into the shaft and housing, and then rotated at a low speed by a motor (belt drive). In the case of the cross roller bearing, rotation irregularity due to torque fluctuation was actually confirmed.

  Furthermore, when the width dimension is about half that of the conventional standard single row ball bearing, the ball diameter is also about half that of the conventional ball bearing, but conversely, the number of balls per row is increased, and the bearing rigidity is conventional. Increased against ball bearings. In addition, when applied to the arm joint of a turning robot, etc., low-speed oscillating rotation is almost the case, so even if the bearing load capacity is reduced by reducing the ball diameter, the rolling fatigue life time is practical. There is no problem.

  Other industrial machines, robot joints and turning mechanisms, machine tool turntables and spindle turning mechanisms, medical equipment, semiconductor / liquid crystal manufacturing equipment, optics and optoelectronic devices, etc. Since there are many applications for rotation, rolling fatigue life time is hardly a problem.

  FIG. 9 is a comparison of calculated moment stiffness of various bearings. In the case of the same size (calculation example is equivalent to bearing name No. 7906A (contact angle 30 °) and the inner and outer diameter dimensions are the same: inner ring inner diameter φ30 mm, outer ring outer diameter φ47 mm), the two rows of narrow angular combinations according to claim 1 In the ball bearings (contact angle 30 °: bearing calculation example), the invention examples A to E in which the radius of curvature of the raceway grooves (Da is the ball diameter) of the inner and outer rings are changed. The moment rigidity is higher than that of the combined angular contact ball bearing and the four-point contact ball bearing. For example, the present invention example B is 2.4 times the cross roller bearing and 1.9 of the conventional standard two-row combined angular contact ball bearing. It is possible to maintain a moment rigidity that is 3.3 times that of a 4-point contact ball bearing.

The design preload clearances are -0.010 mm for the invention examples A to E, standard two-row combination angular contact ball bearings and 4-point contact ball bearings, and -0.001 mm for the cross roller bearings, which are standard in practical use. Calculated as a value.
In addition, the appropriate ball diameter of the narrow ball bearing in the present embodiment varies depending on the presence or absence of a seal or the like, but in order to increase rigidity, if the ball diameter is extremely reduced, the ball and the inner and outer ring raceway grooves Since the surface pressure between the contact portions increases and the pressure scar resistance may be lowered, approximately 30 to 90% of the bearing width (B) is desirable.

Note that the contact angle θ is approximately 60 ° or less, preferably 50 ° or less, more preferably, in order to suppress the ball and the inner / outer ring groove contact portion from climbing onto the shoulder portions of the inner and outer rings when a large moment load is applied. 40 ° or less is preferable, but if it is less than 20 °, the allowable axial load and the allowable moment load are reduced, which is not preferable.
In this embodiment, a ball guide retainer 110 for positioning a large number of balls 103 in the circumferential direction is disposed on the combination surface side of the single row angular ball bearings 100A and 100B, and an annular seal is provided on the opposite side to the combination surface. A body 120 is provided.

  As shown in FIGS. 10 to 12, for example, the ball guide retainer 110 includes a ring portion 111, and pillar portions protruding in the axial direction at a plurality of locations at substantially equal intervals in the circumferential direction on one end portion of the ring portion 111. 112, a plurality of pockets 113 formed between the pillars 112 to hold the balls 103 so as to be rollable in the circumferential direction, and formed at the tip of the pockets 113 opposite to the ring part 111. It has a configuration of a flexible crown-shaped cage including a pair of ball locking portions 114 that prevent the balls 103 from coming out. The cage 110 is made of, for example, a synthetic resin material such as polyamide, polyacetal, or polyphenylene sulfide, and a material in which a reinforcing material such as glass fiber or carbon fiber is mixed into the synthetic resin material is used as necessary.

As shown in FIG. 1, the ball guide cage 110 is arranged on the single row angular ball bearings 100 </ b> A and 100 </ b> B so that the ring portion 111 is on the combination surface side.
Here, as shown in FIG. 13, the curvature center O of the pocket portion 113 coincides with the curvature center of the ball 103 with respect to the axial distance L between the curvature center O of the pocket portion 113 and the tip of the ball locking portion 114. The value ΔG + ΔP obtained by adding the axial clearance ΔP between the pocket surface 113a of the pocket portion 113 and the ball 103 to the axial clearance ΔG between the ends of the ring portions 111 in the two opposing cages 110 in the state where they are set to be (1 ) Is set so as to be small as represented by the formula.

L> ΔG + ΔP (1)
By adopting such a dimensional configuration, due to the inclination of the inner and outer rings due to the moment load, as shown in FIG. 14, the cage 110 is changed from the state shown in the chain line to the state shown in the solid line by one single row angular ball bearing, for example, 100A. When the ring portion 111 moves in the axial direction, the large diameter portion of the ball 103 is brought into contact with the ring engaging portion 114 by contacting the ring portion 111 of the cage 110 of the other single-row angular ball bearing 100B combined with the ring portion 111. The tip is not exceeded (that is, Δ in FIG. 14 becomes a positive value), and it is possible to reliably prevent the retainer 110 from dropping, that is, the ball 103 from being detached from the pocket portion 113 (that is, FIG. 14). A margin is left for Δ in the middle).

Here, the cages 110 of the angular ball bearings 100A and 100B both revolve at substantially the same speed, the relative sliding speed of both the cages 110 is extremely small, and both are in contact on a flat surface. Parts are less likely to wear or break.
The above configuration cannot exert an effect when the bearing is used in a single row. However, in the case of an angular contact ball bearing, the single row can only apply an axial load in one direction because of the structure. Most of them are used in combination, and the frequency of application when implemented is high.

By disposing the retainer 110 so as to have the relationship of the above formula (1) in the combined bearing 100, it is possible to reliably prevent the retainer 110 from coming off from the ball 103, and the ball engagement of the retainer 110. The selection range of the shape design of the stopper 114 can be expanded, and the design is facilitated.
Further, in this embodiment, in order to increase the load capacity and rigidity of the bearing, the circumferential pitch between adjacent balls 103 is shifted as much as possible to the opposite side of the combination side end face (FIG. 1: X ₁ > X ₂ ) and held. The ring part 111 of the vessel 110 is arranged so as to be on the bearing combination end face side so that the distance between the operating points for increasing the moment rigidity can be increased.

15 (b) is a crown-shaped cage 110 having the same basic structure as FIG. 15 (a). However, the pocket portions 113 adjacent to each other at least at one place in the circumferential direction of the ring portion 111 are cut in advance. And it is set as the structure which gave predetermined clearance (DELTA) R between each cut surface.
By adopting such a structure, the rolling element pitch circle diameter deviates from the pitch circle diameter of the cage due to the difference in thermal expansion coefficient between the cage 110 and the inner and outer rings and the variation in the dimensional accuracy and roundness of the cage. Even in this case, the ball 103 has both the flexibility in the radial direction due to the cantilever shape and the elastic deformation in the circumferential direction (flexibility in the circumferential direction) due to the gap ΔR between the cut surfaces. In addition, the tension force between the ball portion and the pocket portion 113 can be buffered to prevent the cage 110 from being damaged or worn, and torque unevenness and heat generation due to sliding contact resistance between the ball 103 and the pocket portion 113 can be further reduced.

  In addition, since the ball bearing of the present invention has a small ball diameter due to its structure, the radial thickness of the ring portion 111 of the cage 110 cannot be increased (as can be understood from FIG. (It is necessary to position the gap between the inner ring outer diameter and outer ring inner diameter with an appropriate gap, and the gap between the inner ring outer diameter and outer ring inner diameter is approximately proportional to the ball diameter and is narrow) Further, due to the narrow structure, the gap in the axial direction is narrow and the axial thickness is inevitably reduced. For this reason, since the ring portion 111 of the cage 110 is extremely smaller than a standard size bearing, and it is difficult to obtain dimensional accuracy such as roundness, the cage structure having the ring portion 111 as shown in FIG. In particular, the above-described cage damage and wear prevention effect and torque unevenness and heat generation reduction effect can be obtained.

Further, in the cage structure shown in FIG. 15 (b), as shown in FIG. 15 (c), the circumference between the opposing cages is formed at the corners of the cut surface and the side surface of the cage ring portion. For example, a C chamfered portion 115 is preferably provided as a guide mechanism for preventing directional interference.
By providing the C chamfered portion 115 in this way, when an external load such as a moment load is applied to the bearing, the balls and cages between the combined bearing rows are caused by the relative inclination of the inner and outer rings and the deformation of the inner and outer rings. The revolving speeds of the cages are different, the cages 110 are relatively deformed in the axial direction, and the cages 110 interfere with each other in the circumferential direction as shown in FIG. possible.

  Therefore, by forming the chamfered portion as described above, as shown in FIG. 15 (e), it is possible to avoid the interference in the circumferential direction between the cages 110 in each row, increasing the rotational torque, Problems such as wear and damage can be eliminated. Although the inclination angle β of the C chamfered portion 115 is not particularly defined, the inclination angle β is preferably 45 ° or less in consideration of the friction coefficient of the contact portion. The width C is selected to be an appropriate value according to the gap ΔG of the opposing cage 110, the amount of axial movement of the cage 110, and the like.

Further, the shape for avoiding interference is not limited to the C chamfered portion 115 as long as it is a structure that can avoid interference such as an R chamfered portion.
Furthermore, when using a resin cage such as polyamide in the cage 110 having a structure in which a gap ΔR is provided at one location of the ring portion 111 as shown in FIG. 15B, the clearance ΔR of the cut portion is as follows: It is preferable to set as follows.

Now, when the temperature around the bearing changes or when the temperature rises during use, the relative expansion amount in the circumferential direction on the ball pitch circle diameter resulting from the difference in the linear expansion coefficient between the inner ring and the ball and the cage is E1, and the circumference of the bearing When the circumferential expansion amount on the ball pitch circle diameter of the cage due to the impregnation of moisture, oil, etc. into the cage, which occurs due to the environmental condition of the cage, is E2, the clearance ΔR of the cut portion is ΔR ≧ E1 + E2. ……… (2)
Set to.

For example, the present invention is as follows when applied to the product of the present invention (the following conditions) in FIG.
・ Inner ring, outer ring and ball material (SUJ2): linear expansion coefficient: 12.5 × 10 ^-6
・ Cage material (polyamide 66): Linear expansion coefficient: 80 × 10 ⁻⁶
Ball pitch circle diameter: 192.5 (mm)
・ Maximum bearing temperature rise value: 100 (° C) (If the normal temperature is 20 ° C, the bearing temperature is 120 ° C)
-Resin water expansion coefficient: 0.3 (%)
Design Example The circumferential relative expansion amount E1 due to the difference in thermal expansion is E1 = (80 × 10 ⁻⁶ −12.5 × 10 ⁻⁶ ) × 100 × 192.5 × π = 4.08 (mm)
The amount of circumferential expansion E2 due to water absorption is
E2 = 0.3 / 100 × 192.5 × π = 1.81 (mm)
Set to.

From the above equation (2), ΔR ≧ 4.08 + 1.81 = 5.89 (mm), and rounded off to ΔR ≧ 6 (mm).
With such a setting, even when the bearing is heated during rotation or used under high-humidity environmental conditions, the gap 110R does not become negative and the cage 110 is stretched in the circumferential direction. Thus, it is possible to prevent problems such as heat generation and torque increase due to interference and tension between the ball 103 and the cage pocket portion 113, and wear and breakage of the pocket.

However, if the clearance ΔR is set larger than necessary, the circumferential rigidity of the bearing becomes non-uniform due to the uneven distribution of balls, and the non-rotation synchronization component (NRRO value) increases in the cage revolution cycle. May occur.
When using this bearing for a circular table device that holds the workpiece, such as when turning a machine tool, factors that increase the NRRO value and deteriorate the surface quality of the workpiece, such as roundness and pulling It becomes.

FIG. 16 is a calculation result of the radial runout amount of the inner ring generated due to the difference in the circumferential rigidity of the bearing when one of the balls is pulled out from the equally distributed state of the present invention in FIG.
The larger the set preload clearance of the bearing (that is, the greater the set preload load), the greater the swinging amount. However, in order to keep it to 0.1 μm or less, which is thought to affect the machining accuracy, the preload clearance is set to about −30 μm or less. It is preferable to suppress.

In addition, since the ball diameter of the present invention product is 6.35 mm, the clearance ΔR is set to a value that satisfies the above equation (2) and is equal to or less than the ball diameter to be used (6 mm in this setting). In this case, by selecting an appropriate preload clearance, it is possible to suppress the swing amount to 0.1 μm or less, which does not cause a practical problem.
This setting is not limited to the resin material, but can be applied when using a material having a large difference in linear expansion coefficient between the inner ring and the ball and the cage material.

In this example, the cage has a linear expansion coefficient larger than that of the inner ring and ball, and the case where the temperature of the bearing rises has been taken as an example. Since the same clearance ΔR is reduced when the temperature of the temperature is lower than the normal temperature, the present invention is also applicable to that case.
Next, as shown in FIG. 17, the annular seal body 120 is configured to be in contact or non-contact with the inner ring 102 or the outer ring 101 corresponding to the side where the annular seal body 120 is inserted. The annular seal body 120 is disposed on the opposite end surfaces of the inner and outer ring axial directions through the ring portion 111 and the ball 103 of the cage 110 of both the single row angular ball bearings 100A and 100B.

The annular seal body 120 is housed in seal housing grooves 121 and 122 formed on the axial end surfaces of the outer ring 101 and the inner ring 102.
The annular seal body 120 is a non-contact type (non-contact with the inner ring 102) that is inserted into a fitting groove 121a formed in the seal housing groove 121 of the outer ring 101, and is reinforced with a reverse L-shaped metal core 125. The rubber seal (for example, nitrile rubber / acrylic rubber or fluorine rubber) 126 is used.

  Here, the rubber seal 126 of the single row angular contact ball bearing 100A includes a fitting portion 126a fitted in the fitting groove 121a, and an annular plate extending from the fitting portion 126a toward the inner ring 102 while being curved outward in the axial direction. Part 126b. Further, the rubber seal 126 of the single row angular ball bearing 100B has a plane symmetrical shape with the rubber seal 126 of the single row angular ball bearing 100A sandwiching the combination surface.

  By forming the rubber seal 126 of the annular seal body 120 in this way, the internal space volume between the annular seal body 120 and the ball 103 can be maintained, and a considerable amount of grease is present in the vicinity of the ball 103 as shown in FIG. Can be encapsulated. Further, since the distance between the ball 103 and the seal surface is short, the grease adhering to the seal is also circulated by rotation, which can contribute to lubrication of the rolling contact portion.

  Further, on the combined surface side of the single-row angular ball bearings 100A and 100B, the ring portion 111 of the retainer 110 causes a space between the inner diameter surface of the outer ring 101 and the outer diameter surface of the ring portion 111 and between the outer diameter surface of the inner ring 102 and the ring portion 111. The opening between the inner diameter surfaces of the two is narrow, and also serves as a labyrinth mechanism. For this reason, the grease can be prevented from leaking to the combined surface, and the bearing can be easily handled until the bearing is assembled into the machine. In the configuration of the above embodiment, the seal mounting side is the outer end surface after the bearing is assembled. In addition, since the ring portion 111 side of the cage 110 is an opposing surface of the two bearings, leakage of grease and entry of foreign matter / dust into the bearing can be reliably prevented.

In the above-described embodiment, the case where the two single-row angular ball bearings 100A and 100B are combined in the back surface with a contact angle of a C shape is not limited to this, but as shown in FIG. The front angle may be combined so that the contact angle is a reverse C shape.
Moreover, although the said embodiment demonstrated the case where the annular seal body 120 was a non-contact type which does not contact the inner ring seal accommodation groove | channel 122, it is not limited to this, In the inner ring seal accommodation groove | channel 122 shown in FIG. A contact-type annular seal body having a lip portion 127 to be contacted or a metal seal caulked in an outer ring seal groove can be applied. In contrast to the above embodiment, the annular seal body 120 may be fitted on the inner ring 102 side so as to be in contact or non-contact with the outer ring.

  In the above embodiment, the pitch circle diameter of the balls 103 is as shown in the following equation (3). However, when it is desired to increase the moment rigidity by increasing the number of balls per row of the bearing, the following equation (4) The pitch circle diameter of the balls 103 may be shifted to the outer ring side, or the following equation (5) may be used as necessary to shift the pitch circle diameter of the balls 103 to the inner ring 102 side. (Not shown).

Ball pitch circle diameter = (inner ring inner diameter + outer ring outer diameter) / 2 (3)
Ball pitch circle diameter> (inner ring inner diameter + outer ring outer diameter) / 2 (4)
Ball pitch circle diameter <(inner ring inner diameter + outer ring outer diameter) / 2 (5)

  If necessary, the ball pitch circle diameters of the left and right ball bearings to be combined may not be the same value, and the diameters of the balls 103 of the left and right ball bearings to be combined may not be the same value. In addition, the sectional dimension ratio (B / H) of the two ball bearings to be combined is not the same. For example, the smaller ball diameter is (B / H) = 0.28, and the larger ball diameter is (B / H). ) = 0.62. Further, the axial pitch of the balls 103 may not be the center of the axial direction, and the axial pitch of the balls 103 may be shifted in the axial direction in order to secure the distance between the application points of the moment and the moment of attachment of the seal and the cage. Good.

  Further, in the above embodiment, a pre-loaded clearance combined angular contact ball bearing is used in order to increase the moment rigidity, but when rigidity and accuracy are not so much required (in contrast, when further lower torque or lower temperature rise is required). If necessary, a combination angular ball bearing with a clearance may be used.

Next, with reference to FIG. 20, the double row angular contact ball bearing which is an example of embodiment of the 2nd aspect (corresponding to Claim 5) of this invention is demonstrated.
In this double row angular contact ball bearing 200, a plurality of balls 203 are rolled by a cage 210 between the double row raceway groove 201a of the outer ring 201 and the raceway grooves 202a of two inner rings 202A and 202B formed separately from each other. The sectional dimension ratio (B2 / H2) between the axial sectional width B2 and the radial sectional height H2 (= (outer ring outer diameter D2—inner ring inner diameter d2) / 2) is (B2 / H2) < 1.2.

  Here, the retainer 210 is a crown-shaped retainer having the same configuration as that of the first embodiment described above, and the same reference numerals are given to the corresponding parts to the first embodiment, and the detailed description thereof will be given here. Although omitted, as shown in FIG. 13 in the first embodiment described above, the pocket portion 113 curvature center O with respect to the axial distance L between the curvature center O of the pocket portion 113 and the tip of the ball locking portion 114. And the axial clearance ΔP between the pocket surface 113a of the pocket portion 113 and the axial direction of the ball 203 in the axial clearance ΔG between the ends of the ring portion 111 in the two cages 210 facing each other in a state where the center of curvature of the ball 203 and the ball 203 are matched. Is set to be small (L> ΔG + ΔP).

Then, seal receiving grooves 221 and 222 similar to those in the first embodiment are formed symmetrically on the left and right axial end surfaces of the outer ring 201 and the inner rings 202A and 202B, respectively. The annular seal body 220 is accommodated symmetrically.
The annular seal body 220 is disposed on the inner and outer ring axial end surface portion on the opposite side through the ball 203 from the ring portion 111 of the cage 210.

The annular seal body 220 is a non-contact type (non-contact with the inner rings 202A and 202B) that is inserted into the fitting groove 221a formed in the seal housing groove 221 of the outer ring 201, and is reinforced with an inverted L-shaped metal core 225. A reinforced rubber seal (for example, nitrile rubber / acrylic rubber or fluorine rubber) 226 is used.
Here, the rubber seal 226 has a fitting portion 226a fitted into the fitting groove 221a, and an annular plate portion 226b extending from the fitting portion 226a toward the inner rings 202A and 202B while being curved outward in the axial direction. .

Here, in the second embodiment, a case where the double-row angular contact ball bearing 200 is replaced with a double-row combination angular contact ball bearing of 7208A (contact angle 30 °) is taken as an example.
7208A has an inner ring inner diameter φ40 mm, an outer ring outer diameter φ80 mm, and an axial sectional width (bearing single body width) B of 18 mm, so the sectional dimension ratio (B / H) = 0.9. Therefore, in the double-row angular contact ball bearing 200 of the present embodiment, the sectional dimension ratio (B2 / H2) = 0.90 (the inner ring axial direction sectional width (bearing single body width) B2 is 18 mm).

As a result, the same effects as those of the first embodiment can be obtained, and the radial load, the axial load in both directions, and the moment load can be received. Torque and higher rigidity can be achieved.
Of course, if necessary, the cross-sectional dimension ratio (B2 / H2) may be set to be less than 0.90 or more than 0.90 (B2 / H2) <1.2).

  Similarly to the first embodiment described above, the curvature center of the pocket portion 113 and the curvature of the ball 203 with respect to the axial distance L between the center of curvature of the pocket portion 113 and the tip of the ball locking portion 114. The value obtained by adding the axial clearance between the pocket surface of the pocket portion 113 and the ball 203 to the axial clearance between the ends of the ring portions 111 in the two opposing cages 210 in a state where the centers coincide with each other is small. Therefore, the balls and the cage can be reliably prevented from falling off due to the influence of the inner and outer ring inclinations caused by the moment load.

Also in this second embodiment, in order to increase the moment rigidity, the ball pitch circle diameter is shifted to the outer ring outer diameter side with a double row angular ball bearing, or the ball diameter and ball pitch circle of each row with a double row angular ball bearing. The diameter may be changed.
In any case, the application examples related to the structure of the annular seal body 220, whether or not it is mounted, the structure of the cage, and the like are based on the single-row ball bearing described in the first embodiment. Moreover, you may use on any conditions of a preload and a clearance gap similarly to embodiment of the said 1st aspect.

It is principal part sectional drawing for demonstrating the combination ball bearing made into the back combination which is an example of 1st aspect (corresponding to Claim 1) of this invention. It is a graph which shows the relationship between a cross-sectional dimension ratio (B / H) and the deformation amount of the inner and outer ring | wheels of a radial direction. It is a graph which shows the relationship between a cross-sectional dimension ratio (B / H) and a cross-sectional secondary moment I. It is explanatory drawing for demonstrating the deformation amount of the radial direction of an inner ring | wheel. It is explanatory drawing for demonstrating the calculation method of the cross-sectional secondary moment of an inner ring | wheel. It is a graph which shows the relationship between a cross-sectional dimension ratio (B / H) and the deformation amount of the inner and outer ring | wheels of a radial direction. It is a graph which shows the relationship between a cross-sectional dimension ratio (B / H) and a cross-sectional secondary moment I. It is a graph which shows the comparison of the moment rigidity of this invention product and the conventional cross roller bearing. It is a graph which shows the comparison of the calculated moment rigidity in various bearings. It is sectional drawing in alignment with the radial direction of a holder | retainer. It is the fragmentary perspective view which looked at the holder | retainer from radial direction inner side. It is an arrow view seen from the arrow Y direction of FIG. It is sectional drawing on the ZZ line of FIG. It is explanatory drawing explaining an effect | action when a holder | retainer moves to an axial direction. (A) is an arrow view seen from the arrow X direction of FIG. 10, (b) is an arrow view showing the modification of (a), (c) is an enlarged view showing a modification of the cage shown in (b). (D) is a figure which shows the interference state of a holder | retainer, (e) is a figure which shows the interference avoidance state of a holder | retainer. It is a characteristic diagram which shows the relationship between a pre-loading gap and the amount of run-out around one ball. It is principal part sectional drawing which shows the state which enclosed grease in FIG. It is principal part sectional drawing which shows the combination bearing made into the front combination. It is principal part sectional drawing which shows the other example of a cyclic | annular sealing body. It is principal part sectional drawing for demonstrating the double row angular contact ball bearing which is an example of embodiment of the 2nd aspect (corresponding to Claim 5) of this invention. It is sectional drawing which shows the conventional deep groove ball bearing. It is a perspective view which shows the holder | retainer of FIG. It is sectional drawing on the BB line of FIG. It is sectional drawing on the AA line of FIG. It is sectional drawing which shows the conventional angular contact ball bearing. It is a side view which shows the holder | retainer of FIG.

Explanation of symbols

100 Combination Ball Bearings 100A, 100B Single-row angular contact ball bearing 101 Outer ring 101a Outer ring raceway groove 102 Inner ring 102a Inner ring raceway groove 103 Ball 110 Ball guide retainer 111 Ring part 112 Column part 113 Pocket part 114 Ball locking part 115 C chamfering part 120 Annular seal bodies 121 and 122 Seal receiving groove 200 Double row angular contact ball bearing 201 Outer ring 201a Outer ring raceway grooves 202A and 202B Inner ring 202a Inner ring raceway groove 230 Ball 220 Annular seal bodies 221 and 222 Seal receiving groove

Claims (8)

Each of the narrow ball bearings is composed of two rows of narrow ball bearings. Each narrow ball bearing has a ring portion on one side and a required number of pocket portions for holding balls on the other side of the ring portion. A combined ball bearing in which the guide retainer is arranged on the combination surface side on the ring side,
The pocket portion has a ball locking portion that prevents a ball formed at a tip portion on the opposite side to the ring portion, and an axial distance between the center of curvature of the pocket portion and the tip of the ball locking portion. In contrast, the axial clearance between the pocket surface of the pocket portion and the ball in the axial clearance between the ring portion end portions of the two opposing cages in a state in which the center of curvature of the pocket portion and the center of curvature of the ball coincide with each other. A combination ball bearing characterized in that the value obtained by adding the directional clearance becomes smaller.   The combination ball bearing according to claim 1, wherein the ball guide cage is formed of a synthetic resin material.   3. Each of the narrow ball bearings is characterized in that an annular seal body is disposed on the inner and outer ring axial end surface portions on the opposite side of the ball guide retainer via the ring portion side and the ball. Combination ball bearings described in 1.   The combined ball bearing according to claim 3, wherein the annular seal body is in contact with at least one of an outer ring and an inner ring of the narrow ball bearing. A crown-shaped ball having a configuration of a narrow double-row ball bearing, each row having a ring portion on one side and a required number of pocket portions holding the ball on the other side of the ring portion. A double row ball bearing in which the guide cage is arranged with the ring side facing the inner side in the axial direction of the bearing,
The pocket portion has a ball locking portion that prevents a ball formed at a tip portion on the opposite side to the ring portion, and an axial distance between the center of curvature of the pocket portion and the tip of the ball locking portion. In contrast, the axial clearance between the pocket surface of the pocket portion and the ball in the axial clearance between the ring portion end portions of the two opposing cages in a state in which the center of curvature of the pocket portion and the center of curvature of the ball coincide with each other. A double-row ball bearing characterized in that the value obtained by adding the directional clearance becomes smaller.   The double-row ball bearing according to claim 5, wherein the ball guide cage is formed of a synthetic resin material.   7. The double row ball bearing according to claim 5 or 6, wherein an annular seal body is disposed on the inner and outer ring axial end surface portions on the opposite side of the ball guide retainer via the ring portion side and the ball. The double row ball bearing described.   The double-row ball bearing according to claim 7, wherein the annular seal body is in contact with at least one of an outer ring and an inner ring of the narrow ball bearing.

Images