JP6071447B2 - Cage, rolling bearing and dental handpiece - Google Patents

Description

  The present invention relates to a cage, a rolling bearing provided with the cage, and a dental handpiece.

Generally, a rolling bearing rolls in a state in which an outer ring and an inner ring arranged on the same axis, a plurality of rolling elements arranged between the inner ring and the outer ring, and the rolling elements are evenly arranged in the circumferential direction. A retainer that can be freely held.
By the way, in the case of a rolling bearing cage, when used in a machine tool or dental handpiece that rotates at high speed, it is an issue to improve durability characteristics such as heat resistance, seizure resistance, and wear resistance. Become.

In view of the above-described problems, it is conceivable that the cage is formed of a resin material having excellent heat resistance and wear resistance, such as a polyamideimide resin.
However, the polyamide-imide resin is generally expensive compared to other resin materials. Furthermore, since polyamideimide resin is difficult to injection mold, it is necessary to form a cage by cutting, and the processing cost is also expensive.

Therefore, for example, a technology for injection molding a cage using a resin material in which glass fiber, carbon fiber, or the like is blended with heat-resistant injection-moldable polyphenylene sulfide (PPS), polyether ether ketone (PEEK), or the like is disclosed. (For example, refer to Patent Document 1).
Furthermore, in order to improve the seizure resistance of the cage, a technique in which a dynamic pressure groove in which V-shaped grooves in a plan view are arranged in a herringbone shape is formed on the guide surface of the cage made of an injection-moldable resin material. Is disclosed (for example, see Patent Document 2).

Japanese Patent No. 4962103 JP 2008-19937 A

However, in the cage described in Patent Document 1, durability such as wear resistance of the cage may not be sufficiently ensured only by blending glass fiber or carbon fiber.
Further, in the cage described in Patent Document 2, since the dynamic pressure grooves are formed by arranging the grooves in a herringbone shape, the structure of the mold may be complicated and the cost may be increased. .
Furthermore, in the cage described in Patent Document 2, since the dynamic pressure groove is not formed around the through hole in which the rolling element is accommodated, the cage is deformed when the cage is rotated, and the outer ring and the inner ring There is a risk of contact with the cage at high contact pressure. In addition, since the shape of the dynamic pressure groove is complicated, the cage cannot be formed with high accuracy, and the outer ring, the inner ring, and the cage may come into contact with each other at a high contact pressure when the cage is rotated. Therefore, there is a possibility that the durability of the cage cannot be secured sufficiently.

  Then, this invention is made | formed in view of the situation mentioned above, Comprising: It aims at provision of a low-cost retainer, a rolling bearing, and a dental handpiece while ensuring durability.

In order to solve the above-described problems, the cage of the present invention rolls in a state in which a plurality of rolling elements arranged on a ring body having an outer ring and an inner ring arranged on the same axis are evenly arranged in the circumferential direction. An annular cage that is movably held, wherein at least one of an outer circumferential surface and an inner circumferential surface of the cage has a fluid dynamic pressure between the ring body and the cage when the cage is rotated. And a plurality of the dynamic pressure grooves are formed along the axial direction of the cage and parallel to the circumferential direction .
A first side surface disposed on the downstream side in the relative rotational direction of the ring body as viewed from the cage;
A second side surface formed continuously with the first side surface and disposed upstream of the ring body in the relative rotational direction as viewed from the cage, wherein the first side surface is more than the second side surface. The area is formed wide, and when viewed from the axial direction, is formed so as to be along the circumferential direction rather than the second side surface. The dynamic pressure groove and the second dynamic pressure groove are provided, and the bottom portion of the first dynamic pressure groove and the bottom portion of the second dynamic pressure groove are formed at positions shifted from each other in the circumferential direction. It is characterized by having.

According to the present invention, by providing the dynamic pressure groove on at least one of the outer peripheral surface and the inner peripheral surface of the cage, the outer pressure ring that constitutes the ring body and the dynamic pressure groove of the cage, Fluid dynamic pressure can be generated between at least one of the inner rings. Thereby, at the time of rotation of a cage | basket, it can suppress that a cage | basket and at least any one of the outer ring | wheel and inner ring | wheels which oppose a dynamic pressure groove contact with a high contact pressure. In addition, since the dynamic pressure grooves are formed in plural along the axial direction of the cage and parallel to the circumferential direction, rigidity can be ensured over the entire circumference of the cage. Therefore, it is possible to suppress the cage from being deformed when the cage is rotated, and to prevent the outer ring and the inner ring constituting the ring body from coming into contact with the cage at a high contact pressure. Thereby, since the wear of the cage can be suppressed, the durability of the cage can be ensured.
In addition, since the wear of the cage can be suppressed, a resin material having lower heat resistance and wear resistance than the prior art can be employed. Further, for example, a plurality of dynamic pressure grooves that generate fluid dynamic pressure can be easily formed with high accuracy simply by sliding the mold in the axial direction. Therefore, a cage that can ensure durability can be formed at low cost.
Further, the first side surface disposed on the downstream side in the relative rotation direction of the ring body as viewed from the cage has an area larger than the second side surface disposed on the upstream side in the relative rotation direction of the ring body as viewed from the cage. Since it is widely formed, a predetermined fluid dynamic pressure can be generated by the first side surface disposed on the downstream side in association with the relative rotation between the cage and the ring body. In addition, the first side surface disposed on the downstream side in the relative rotation direction when viewed from the cage is more circumferential than the second side surface disposed on the upstream side in the relative rotation direction when viewed from the cage. Since it is formed along the direction, air resistance can be suppressed by moving the air along the first side surface from the upstream side to the downstream side in the relative rotation direction of the ring body as viewed from the cage. . Therefore, a rolling bearing with good rotational efficiency can be formed.
Further, since the bottom portion of the first dynamic pressure groove and the bottom portion of the second dynamic pressure groove are formed at positions shifted from each other in the circumferential direction, a thin portion is formed in the radial direction of the cage. Can be prevented. Therefore, even when the dynamic pressure grooves are provided on both the inner peripheral surface and the outer peripheral surface of the cage, the strength of the cage can be ensured.

  An annular base portion; and a plurality of pairs of claw portions that are erected from the base portion toward one side in the axial direction and are capable of holding the rolling element in a freely rollable manner. The pressure groove is formed on at least one of an inner peripheral surface and an outer peripheral surface of the base portion.

  According to the present invention, since the rolling elements are provided with a plurality of pairs of claw portions that can be freely rolled, the rolling elements can be reliably held. A cage provided with a pair of claw portions is suitable as a cage for a so-called deep groove ball bearing.

  In addition, the base portion includes an overhanging portion that is formed so as to protrude either inside or outside in the radial direction, and the dynamic pressure groove is formed at least on a peripheral surface of the overhanging portion. Yes.

  According to the present invention, when the rolling bearing is formed, the peripheral surface of the projecting portion that projects from the base portion to either the inside or the outside in the radial direction can be used as the cage guide surface. Furthermore, by forming a dynamic pressure groove on the cage guide surface, which is the peripheral surface of the overhang portion, when the cage rotates, the cage guide surface formed on the overhang portion of the cage, the outer ring and the inner ring At least one of them can be prevented from contacting at a high contact pressure. Therefore, since the wear of the cage can be suppressed, the durability of the cage can be ensured.

  The rolling bearing according to the present invention includes the above-described cage, and the dynamic pressure groove is formed at least on a cage guide surface of the cage.

  According to the present invention, since the cage is provided and the dynamic pressure groove is formed at least on the cage guide surface, when the fluid dynamic pressure is generated, at least one of the cage guide surface, the outer ring, and the inner ring is generated. It can suppress that a heel contacts with a high contact pressure. Therefore, durability can be ensured and a low-cost rolling bearing can be formed.

  In addition, when the rolling bearing is used, if the relative rotational speed between the inner ring and the cage is higher than the relative rotational speed between the outer ring and the cage, the movement on the inner peripheral surface of the cage. When a relative rotational speed between the outer ring and the cage is higher than a relative rotational speed between the inner ring and the cage, the dynamic pressure groove is provided on the outer peripheral surface of the cage. It is characterized by that.

  According to the present invention, when the relative rotation speed between the inner ring and the cage is higher than the relative rotation speed between the outer ring and the cage, a dynamic pressure groove is provided on the inner circumferential surface of the cage, and the outer ring and the cage When the relative rotational speed of the inner ring is higher than the relative rotational speed of the inner ring and the cage, a dynamic pressure groove is provided on the outer peripheral surface of the cage. Fluid dynamic pressure can be generated between the heel and the cage. Thereby, it can suppress that either the outer ring | wheel and an inner ring | wheel with a high relative rotational speed with respect to a holder | retainer, and a holder | retainer contact with a high contact pressure. Therefore, since the wear of the cage can be suppressed, the durability of the cage can be ensured. In particular, the higher the rotation speed, the higher the fluid dynamic pressure can be generated, and the wear of the cage can be reliably suppressed, so that it is suitable for rolling bearings such as dental handpieces.

  Moreover, the dental handpiece of the present invention is characterized by including the above-described rolling bearing.

  According to the present invention, since the rolling bearing described above is provided, durability can be ensured and a low-cost dental handpiece can be formed.

According to the present invention, by providing the dynamic pressure groove on at least one of the outer peripheral surface and the inner peripheral surface of the cage, the outer pressure ring that constitutes the ring body and the dynamic pressure groove of the cage, Fluid dynamic pressure can be generated between at least one of the inner rings. Thereby, at the time of rotation of a cage | basket, it can suppress that a cage | basket and at least any one of the outer ring | wheel and inner ring which oppose a dynamic pressure groove contact with a high contact pressure. In addition, since the dynamic pressure grooves are formed in plural along the axial direction of the cage and parallel to the circumferential direction, rigidity can be ensured over the entire circumference of the cage. Therefore, it is possible to suppress the cage from being deformed when the cage is rotated, and to prevent the outer ring and the inner ring constituting the ring body from coming into contact with the cage at a high contact pressure. Thereby, since the wear of the cage can be suppressed, the durability of the cage can be ensured.
In addition, since the wear of the cage can be suppressed, a resin material having lower heat resistance and wear resistance than the prior art can be employed. Further, for example, a plurality of dynamic pressure grooves that generate fluid dynamic pressure can be easily formed with high accuracy simply by sliding the mold in the axial direction. Therefore, a cage that can ensure durability can be formed at low cost.

It is explanatory drawing of a dental handpiece. It is side surface sectional drawing containing the central axis of the head part of a dental handpiece. It is side surface sectional drawing of the rolling bearing which concerns on 1st embodiment. It is an external appearance perspective view of the retainer concerning a first embodiment. It is explanatory drawing when the retainer which concerns on 1st embodiment is seen from the inner side of radial direction. It is explanatory drawing when the retainer which concerns on 1st embodiment is seen from an axial direction. It is explanatory drawing when the rolling bearing which concerns on the modification of 1st embodiment is seen from an axial direction. It is side surface sectional drawing of the rolling bearing which concerns on 2nd embodiment. It is explanatory drawing when the retainer which concerns on 2nd embodiment is seen from the inner side of radial direction. It is explanatory drawing when the retainer which concerns on 2nd embodiment is seen from an axial direction. It is explanatory drawing of the other shape of a dynamic pressure groove.

Hereinafter, a retainer (corresponding to a “retainer” in claims) according to the first embodiment, a rolling bearing and a dental handpiece provided with the retainer will be described. In addition, below, after demonstrating the dental handpiece which concerns on embodiment, it demonstrates in order of the rolling bearing which concerns on 1st embodiment, and a retainer.
FIG. 1 is an explanatory view of a dental handpiece 1.
As shown in FIG. 1, the dental handpiece 1 is provided with various tools 5 such as a drill and a grindstone in a detachable manner on a head portion 3 provided on a distal end side of a main body portion 2. In the following description, the rotation axis of the tool 5 of the dental handpiece 1 will be described as the central axis O.

FIG. 2 is a side cross-sectional view including the central axis O of the head portion 3 of the dental handpiece 1.
As shown in FIG. 2, the tool 5 is attached to the rotary shaft 7 in the head portion 3. Inner rings 36 and 36 of a pair of rolling bearings 30 and 30 are extrapolated on the rotary shaft 7 side by side in the axial direction. The outer rings 31, 31 of the pair of rolling bearings 30, 30 are respectively attached to the housing 8 of the head portion 3. Thereby, the rotating shaft 7 and the tool 5 are rotatably supported by the housing 8 of the head part 3 via a pair of rolling bearings 30 and 30.
A turbine blade 9 is provided between the pair of rolling bearings 30 on the outer peripheral surface of the rotating shaft 7. The rotary shaft 7, the tool 5, and the inner rings 36, 36 of the pair of rolling bearings 30, 30 rotate around the central axis O by injecting high-pressure air to the turbine blade 9. The rotating shaft 7 and the tool 5 can rotate only in one direction θ (hereinafter referred to as “rotating direction θ”), for example. Moreover, the rotation speed of the tool 5 of the dental handpiece 1 of this embodiment is, for example, about 300000 rpm to 400000 rpm.

(Rolling bearing of the first embodiment)
FIG. 3 is a side sectional view of the rolling bearing 30 according to the first embodiment. Since the pair of rolling bearings 30 and 30 (see FIG. 2) have the same shape, only one (upper side in FIG. 2) rolling bearing 30 will be described below, and the other (lower side in FIG. 2). The description of the rolling bearing 30 is omitted. Further, the center axis of the rolling bearing 30 is in common with the center axis O of the tool 5 of the dental handpiece 1. Therefore, in the following description, the central axis of the rolling bearing 30 is the central axis O, and the rotational direction of the inner ring 36 of the rolling bearing is θ. In the following description, a direction along the central axis O is referred to as an “axial direction”, a direction perpendicular to the central axis O is referred to as a “radial direction”, and a direction around the central axis O is referred to as a “circumferential direction”.

  As shown in FIG. 3, the rolling bearing 30 includes an outer ring 31 and a ring body 20 including an inner ring 36 disposed coaxially with the outer ring 31 on the inner side in the radial direction of the outer ring 31, and an outer ring 31 constituting the ring body 20. And a plurality of rolling elements 35 disposed between the inner ring 36 and a retainer 60 that holds the plurality of rolling elements 35 so as to be freely rollable in a state of being evenly arranged in the circumferential direction.

The outer ring 31 constituting the ring body 20 is a cylindrical member made of a metal material such as stainless steel having a predetermined thickness in the axial direction, and is formed, for example, by forging or machining.
An outer ring rolling surface 34 is formed at an intermediate portion in the axial direction of the inner peripheral surface 32 of the outer ring 31. The outer ring rolling surface 34 has a side section formed in an arc shape along the outer surface of the rolling element 35. The curvature radius in the side surface cross section of the outer ring rolling surface 34 is formed to be substantially the same as or slightly larger than the curvature radius of the outer surface of the rolling element 35. The outer ring rolling surface 34 is formed over the entire circumference of the inner circumferential surface 32 of the outer ring 31, and the outer surfaces of a plurality of rolling elements 35 arranged in an annular shape can come into contact with each other.

The inner ring 36 constituting the ring body 20 is a substantially cylindrical member made of a metal material such as stainless steel having the same thickness as the outer ring 31 in the axial direction, and is formed by forging or machining, for example. .
An inner ring rolling surface 39 is formed at an axial intermediate portion of the outer circumferential surface 37 of the inner ring 36. The inner ring rolling surface 39 has a side section formed in an arc shape along the outer surface of the rolling element 35. The curvature radius in the side surface cross section of the inner ring rolling surface 39 is formed to be substantially the same as or slightly larger than the curvature radius of the outer surface of the rolling element 35. The inner ring rolling surface 39 is formed over the entire circumference of the outer circumferential surface 37 of the inner ring 36, and the outer surfaces of the plurality of rolling elements 35 arranged in an annular shape can come into contact with each other.
The inner ring 36 rotates at high speed around the central axis O together with the rotating shaft 7 and the tool 5 (both see FIG. 2) of the dental handpiece 1.

  The rolling element 35 is formed in a spherical shape from a metal material such as stainless steel or a ceramic material such as zirconia. A plurality of rolling elements 35 (seven in this embodiment) are arranged between the outer ring rolling surface 34 of the outer ring 31 and the inner ring rolling surface 39 of the inner ring 36, and the outer ring rolling surface 34 and the inner ring rolling surface. It rolls along 39. The plurality of rolling elements 35 are equally arranged in an annular shape along the circumferential direction so as to be freely rollable by a retainer 60.

(Retainer according to the first embodiment)
The retainer 60 is made of, for example, a synthetic resin such as polyphenylene sulfide (PPS), polyether ether ketone (PEEK), liquid crystal polymer (LCP), polyether sulfone (PES), polyimide (PI), polyamideimide (PAI), or the like. It is a cylindrical member. The retainer 60 is disposed coaxially with the inner ring 36 and the outer ring 31 between the inner ring 36 and the outer ring 31, and the plurality of rolling elements 35 disposed between the inner ring 36 and the outer ring 31 are arranged in the circumferential direction. It is held so that it can roll freely in a state of being evenly arranged. The axial length (thickness) of the retainer 60 is formed substantially the same as the axial thickness of the inner ring 36 and the outer ring 31.

  Further, when the retainer 60 is disposed between the inner ring 36 and the outer ring 31, the distance between the outer peripheral surface 62 of the retainer 60 and the inner peripheral surface 32 of the outer ring 31 is such that the inner peripheral surface 61 of the retainer 60 and the inner ring 36 are separated. It is formed so as to be narrower than the distance from the outer peripheral surface 37. When the inner ring 36 rotates at high speed and the plurality of rolling elements 35 revolve around the central axis O in the rotation direction θ, the retainer 60 rotates in the rotation direction θ as the plurality of rolling elements 35 revolve.

FIG. 4 is an external perspective view of the retainer 60.
As shown in FIG. 4, the peripheral wall 60a of the retainer 60 is formed with a plurality of through holes 63 (seven in this embodiment) penetrating in the radial direction. The through holes 63 are formed at substantially equal intervals in the circumferential direction at an intermediate portion in the axial direction of the retainer 60.
The diameter of the through hole 63 is formed to be larger than the diameter of the rolling element 35 (see FIG. 2), and the rolling element 35 can be loosely inserted. Thereby, the rolling element 35 can be held in the through hole 63 so as to be freely rollable by the retainer 60.

FIG. 5 is an explanatory diagram when the retainer 60 is viewed from the outside in the radial direction.
As shown in FIG. 5, the outer peripheral surface 62 of the retainer 60 is provided with a plurality of (14 in the present embodiment) dynamic pressure grooves 70 that generate fluid dynamic pressure. The dynamic pressure groove 70 has an outer peripheral surface 62 that is recessed inward in the radial direction, and is formed along the axial direction of the retainer 60 and in parallel with the circumferential direction. In the present embodiment, the outer peripheral surface 62 of the retainer 60 faces the inner peripheral surface 32 of the outer ring 31 that functions as a guide wheel, and a retainer guide surface 62a that generates fluid dynamic pressure between the outer ring 31 and the outer ring 31 (claims). Equivalent to “Cage guide surface”.

FIG. 6 is an explanatory diagram when the retainer 60 is viewed from the axial direction.
As shown in FIG. 6, the dynamic pressure groove 70 has a relative rotation direction of the outer ring 31 (see FIG. 3) when viewed from the retainer 60 (in this embodiment, the retainer 60 rotates in the rotation direction θ and the outer ring 31 is fixed). Therefore, it corresponds to the direction opposite to the rotational direction θ.) And the second side surface disposed on the upstream side in the relative rotational direction of the outer ring 31 when viewed from the retainer 60. 72, and is substantially V-shaped when viewed in the axial direction. The area of the first side surface 71 is formed to be larger than the area of the second side surface 72. Thereby, a predetermined fluid dynamic pressure can be generated between the retainer guide surface 62 a of the retainer 60 and the inner peripheral surface 32 (see FIG. 3) of the outer ring 31.

  Here, when it is defined as a straight line L1 (see a two-dot chain line in FIG. 6) along the radial direction and passing through the boundary between the first side surface 71 and the second side surface 72, the inclination angle α of the first side surface 71 with respect to the straight line L1 is The inclination angle β of the second side surface 72 with respect to the straight line L1 is set to be larger. By forming the first side surface 71 and the second side surface 72 of the dynamic pressure groove 70 in this way, the second side surface 72 is made to extend along the radial direction from the first side surface 71, and the first side surface 71 is moved to the second side surface 72. It can form so that it may follow along the circumferential direction rather. Thereby, the air resistance can be suppressed by moving the air between the retainer guide surface 62 a of the retainer 60 and the inner peripheral surface 32 (see FIG. 3) of the outer ring 31 along the first side surface 71.

Further, as shown in FIG. 5, the dynamic pressure grooves 70 are formed along the axial direction of the retainer 60 and in parallel with the circumferential direction, and therefore, the retainer 60 is formed rather than the case where the dynamic pressure grooves 70 are not formed. The section modulus of the cross section perpendicular to the axial direction can be improved. Therefore, rigidity is ensured over the entire circumference of the peripheral wall 60a of the retainer 60. Moreover, the bottom part 70a which becomes the boundary of the 1st side surface 71 and the 2nd side surface 72 which forms the dynamic pressure groove 70 is arrange | positioned so that the through-hole 63 may be straddled along an axial direction. Therefore, also in the vicinity of the through hole 63 of the retainer 60, the section modulus of the cross section orthogonal to the axial direction can be improved, so that rigidity is ensured.
Moreover, since the dynamic pressure groove 70 is provided along the axial direction of the retainer 60, the dynamic pressure groove 70 can be formed by sliding the mold along the axial direction. Therefore, the retainer 60 can be easily formed by injection molding.

(Operation of the first embodiment)
Next, the operation of the retainer 60 and the rolling bearing 30 according to the first embodiment will be described.
As shown in FIG. 2, in the rolling bearing 30 of the first embodiment, the outer ring 31 is fixed to the head portion 3 of the dental handpiece 1, and the inner ring 36 is the rotating shaft 7 and the tool 5 of the dental handpiece 1. At the same time, it rotates at high speed around the central axis O in the rotation direction θ. At this time, the plurality of rolling elements 35 revolve around the central axis O in the rotation direction θ due to the high speed rotation of the inner ring 36. Furthermore, the retainer 60 rotates in the rotation direction θ as the plurality of rolling elements 35 revolve.
Here, as shown in FIG. 4, a dynamic pressure groove 70 is provided on the outer peripheral surface 62 (the retainer guide surface 62 a) of the retainer 60. Therefore, as shown in FIG. 3, fluid dynamic pressure is generated between the retainer guide surface 62 a of the retainer 60 and the inner peripheral surface 32 of the outer ring 31 due to the high-speed rotation of the inner ring 36. During rotation, the contact between the retainer 60 and the outer ring 31 is suppressed.

(Effects of the first embodiment)
According to the first embodiment, by providing the dynamic pressure groove 70 on the outer peripheral surface 62 of the retainer 60, the dynamic pressure groove 70 of the retainer 60, the outer ring 31 that forms the ring body 20, facing the dynamic pressure groove 70, and In the meantime, fluid dynamic pressure can be generated. Thereby, it can suppress that the retainer 60 and the outer ring | wheel 31 which opposes a dynamic pressure groove contact with a high contact pressure. Further, since the dynamic pressure groove 70 is formed in plural along the axial direction of the retainer 60 and in parallel with the circumferential direction, rigidity can be ensured over the entire circumference of the retainer 60. Therefore, it is possible to suppress the retainer 60 from being deformed when the retainer 60 is rotated, and to prevent the outer ring 31 and the retainer 60 from contacting with a high contact pressure. Thereby, since the wear of the retainer 60 can be suppressed, the durability of the retainer 60 can be ensured.
In addition, since the wear of the retainer 60 can be suppressed, a resin material having lower heat resistance and wear resistance than the prior art can be employed. Further, for example, by simply sliding the mold in the axial direction, the plurality of dynamic pressure grooves 70 for generating fluid dynamic pressure can be easily formed with high accuracy. Therefore, the retainer 60 that can ensure durability can be formed at low cost.

  Further, the first side surface 71 disposed on the downstream side in the relative rotation direction of the outer ring 31 constituting the ring body 20 when viewed from the retainer 60 is arranged in the relative rotation direction of the outer ring 31 constituting the ring body 20 as viewed from the retainer 60. Since the area is formed wider than the second side surface 72 disposed on the upstream side, a predetermined fluid dynamic pressure is generated by the first side surface 71 disposed on the downstream side in accordance with the relative rotation between the retainer 60 and the outer ring 31. Can be generated. Further, the first side surface 71 disposed on the downstream side in the relative rotational direction when viewed from the retainer 60 is more than the second side surface 72 disposed on the upstream side in the relative rotational direction when viewed from the retainer 60 when viewed from the axial direction. Is also formed along the circumferential direction, so that air is moved along the first side surface 71 from the upstream side to the downstream side in the relative rotation direction of the outer ring 31 when viewed from the retainer 60, thereby reducing the air resistance. Can be suppressed. Therefore, the rolling bearing 30 with good rotational efficiency can be formed.

  Further, the retainer 60 can be formed at low cost by injection molding with a resin material.

  In addition, the rolling bearing 30 of the first embodiment includes the retainer 60 described above, and the dynamic pressure groove 70 is formed at least on the retainer guide surface 62 a side. Therefore, the retainer guide surface 62 a and the inner peripheral surface 32 of the outer ring 31. Can be prevented from contacting at a high contact pressure. Therefore, it is possible to form the rolling bearing 30 that can secure durability and is low in cost.

  Moreover, since the dental handpiece 1 of 1st embodiment is equipped with the above-mentioned rolling bearing 30, durability can be ensured and the low-cost dental handpiece 1 can be formed.

(Modification of the first embodiment)
FIG. 7 is an explanatory diagram when the rolling bearing 30 according to the modification of the first embodiment is viewed from the axial direction.
Then, the rolling bearing 30 and the retainer 60 which concern on the modification of 1st embodiment are demonstrated.
In the rolling bearing 30 according to the first embodiment, the dynamic pressure groove 70 is formed only on the outer peripheral surface 62 of the retainer 60 (see FIGS. 3 and 4).
On the other hand, as shown in FIG. 7, in the rolling bearing 30 according to the modification of the first embodiment, in addition to the first dynamic pressure groove 70 formed on the outer peripheral surface 62 of the retainer 60, This is different from the first embodiment in that a second dynamic pressure groove 75 is formed on the inner peripheral surface 61 of the retainer 60. Detailed description of the same components as those in the first embodiment will be omitted, and only different portions will be described.

  As shown in FIG. 7, when the retainer 60 is disposed between the inner ring 36 and the outer ring 31, the distance between the outer peripheral surface 62 of the retainer 60 and the inner peripheral surface 32 of the outer ring 31, and the inner periphery of the retainer 60. The distance between the surface 61 and the outer peripheral surface 37 of the inner ring 36 is formed to be substantially equal. When the inner ring 36 rotates at high speed and the plurality of rolling elements 35 revolve around the central axis O in the rotation direction θ, the retainer 60 rotates in the rotation direction θ as the plurality of rolling elements 35 revolve.

A second dynamic pressure groove 75 is formed on the inner peripheral surface 61 of the retainer 60. The second dynamic pressure groove 75 has an inner peripheral surface 61 that is recessed outward in the radial direction, and is formed along the axial direction of the retainer 60 and in parallel with the circumferential direction.
The second dynamic pressure groove 75 has a relative rotation direction of the inner ring 36 (see FIG. 3) as viewed from the retainer 60 (in this modification, the inner ring 36 rotates at a higher speed than the retainer 60, and therefore the rotation direction θ of the inner ring 36). The first side surface 76 disposed on the downstream side of the retainer 60 and the second side surface 77 disposed on the upstream side in the relative rotational direction of the inner ring 36 when viewed from the retainer 60 are substantially V-shaped when viewed from the axial direction. Is formed. The area of the first side surface 76 is formed to be larger than the area of the second side surface 77. Thereby, a predetermined fluid dynamic pressure can be generated between the retainer 60 and the outer peripheral surface 37 of the inner ring 36.
Similarly to the first dynamic pressure groove 70, the second dynamic pressure groove 75 is formed such that the first side surface 76 is more along the circumferential direction than the second side surface 77 when viewed from the axial direction.
Here, the bottom portion 70a of the first dynamic pressure groove 70 and the bottom portion 75a of the second dynamic pressure groove 75 are formed so as to be shifted from each other in the circumferential direction. For example, in the present embodiment, the bottom portion 75 a of the second dynamic pressure groove 75 is disposed at a position corresponding to the intermediate portion in the circumferential direction of the first dynamic pressure groove 70. As a result, the bottom portion 70a of the first dynamic pressure groove 70 and the bottom portion 75a of the second dynamic pressure groove 75 are not formed at the same position in the circumferential direction, so that the retainer 60 is thin in the radial direction. It is possible to suppress the formation of a large part.

(Operation of Modification of First Embodiment)
As shown in FIG. 7, in the rolling bearing 30 according to the modification of the first embodiment, the outer ring 31 is fixed to the head portion 3 (see FIG. 2) of the dental handpiece 1. When the dental handpiece 1 is used, the inner ring 36 rotates at a high speed in the rotation direction θ around the central axis O together with the rotation shaft 7 and the tool 5 (both see FIG. 2) of the dental handpiece 1. At this time, the retainer 60 rotates in the rotational direction θ as the plurality of rolling elements 35 revolve. Accordingly, when the dental handpiece 1 is used (that is, when the rolling bearing 30 is used), the relative rotational speed between the outer ring 31 and the retainer 60 is higher than the relative rotational speed between the inner ring 36 and the retainer 60.
Here, since the first side surface 76 of the second dynamic pressure groove 75 is formed so as to be along the circumferential direction rather than the second side surface 77, the air runs along the first side surface 76 when the inner ring 36 rotates at a high speed. The air resistance is suppressed and the predetermined fluid dynamic pressure is generated. Further, a predetermined fluid dynamic pressure is generated between the inner peripheral surface 32 of the outer ring 31 and the outer peripheral surface 62 of the retainer 60 (that is, the retainer guide surface 62a) as in the first embodiment.

(Effects of Modification of First Embodiment)
According to the modification of the first embodiment, when the relative rotational speed between the outer ring 31 and the retainer 60 is higher than the relative rotational speed between the inner ring 36 and the retainer 60, the second dynamic pressure is applied to the outer peripheral surface 62 of the retainer 60. Since the groove 75 is provided, fluid dynamic pressure can be generated between the outer ring 31 and the retainer 60 having a high relative rotational speed with respect to the retainer 60. Thereby, when the retainer 60 rotates, it can suppress that the outer ring | wheel 31 and the retainer 60 contact with a high contact pressure. Therefore, since the wear of the retainer 60 can be suppressed, the durability of the retainer 60 can be ensured. In particular, the higher the rotation speed, the higher the fluid dynamic pressure can be generated, and the wear of the retainer 60 can be reliably suppressed, so that it is suitable for the rolling bearing 30 such as the dental handpiece 1.

(Second embodiment)
FIG. 8 is a side sectional view of the rolling bearing 230 according to the second embodiment.
Next, the rolling bearing 230 and the retainer 260 according to the second embodiment will be described.
In the rolling bearing 30 according to the first embodiment, the retainer 60 is formed in a cylindrical shape, and a through-hole 63 capable of holding the rolling element 35 in a freely rolling manner is formed in the peripheral wall 60a (see FIG. 3). ).
On the other hand, as shown in FIG. 8, in the rolling bearing 230 according to the second embodiment, the retainer 260 can hold the base portion 260a and the rolling element 35 in a freely rollable manner. It differs from 1st embodiment by the point provided with 265,265. Detailed description of the same components as those in the first embodiment will be omitted, and only different portions will be described.

FIG. 9 is an explanatory diagram when the retainer 260 according to the second embodiment is viewed from the outside in the radial direction.
As shown in FIG. 9, the retainer 260 according to the second embodiment is erected from the base portion 260a toward the one side in the axial direction (upper side in FIG. 9) from the base portion 260a, and the rolling element 35 (FIG. 8). A pair of claw portions 265 and 265 (seven sets in the present embodiment) that can be held in a rollable manner.
As shown in FIG. 8, the base portion 260a is arranged coaxially with the outer ring 31 and the inner ring 36, and is formed in an annular shape. The base portion 260a has a predetermined thickness in the radial direction, and is disposed at an intermediate portion between the outer ring 31 and the inner ring 36 in the radial direction.

An end portion on the other side (lower side in FIG. 8) of the base portion 260a is a protruding portion 264 that is formed to protrude outward in the radial direction.
When the retainer 260 is disposed between the inner ring 36 and the outer ring 31 on the same axis as the inner ring 36 and the outer ring 31, the retainer 260 is separated from the outer peripheral surface 262 of the overhang portion 264 and the inner peripheral surface 32 of the outer ring 31. The distance is formed to be narrower than the distance between the inner peripheral surface 261 of the retainer 260 and the outer peripheral surface 37 of the inner ring 36. When the inner ring 36 rotates at a high speed and the plurality of rolling elements 35 revolve around the central axis O in the rotation direction θ, the retainer 260 rotates in the rotation direction θ as the plurality of rolling elements 35 revolve.

FIG. 10 is an explanatory diagram when the retainer 260 according to the second embodiment is viewed from the axial direction.
As shown in FIG. 10, a plurality of dynamic pressure grooves 70 that generate fluid dynamic pressure are provided on the outer peripheral surface 262 of the overhang portion 264 of the retainer 260. That is, the outer peripheral surface 262 of the retainer 260 faces the inner peripheral surface 32 of the outer ring 31 that functions as a guide wheel, and the retainer guide surface 262a that generates fluid dynamic pressure between the outer ring 31 and the retainer 260 Equivalent to the “vessel guide surface”).
The dynamic pressure groove 70 has an outer peripheral surface 262 that is recessed inward in the radial direction, and is formed along the axial direction of the retainer 260 and parallel to the circumferential direction. The configuration of the dynamic pressure groove 70 is the same as that in the first embodiment. That is, the area of the first side surface 71 is formed to be larger than the area of the second side surface 72, and the inclination angle α of the first side surface 71 with respect to the straight line L1 is the inclination of the second side surface 72 with respect to the straight line L1. It is set to be larger than the angle β. Therefore, even when the dynamic pressure groove 70 is formed on the outer peripheral surface 262 of the overhang portion 264 of the retainer 260 as in the present embodiment, the same effect as in the first embodiment can be obtained.

As shown in FIG. 9, seven pairs of claw portions 265 and 265 are erected on the end surface on one side (the upper side in FIG. 9) of the base portion 260a in the axial direction.
The pair of claw portions 265 and 265 are erected along the axial direction in a state of being curved in an arc shape so that the distance between the respective distal ends approaches each other from the other side in the axial direction to the one side. ing.
The inner surfaces between the pair of claw portions 265 and 265 are continuously formed in an arc shape and have a curvature slightly larger than the diameter of the rolling element 35 (see FIG. 8). Between the pair of claw portions 265 and 265 is a pocket portion 263 that can hold the rolling element 35 in a freely rollable manner. The opening diameter between the tip portions of the pair of claw portions 265 and 265 is smaller than the diameter of the rolling element 35. Therefore, the pair of claw portions 265 and 265 can be held so as to roll freely without dropping the rolling elements 35.

(Effect of the second embodiment)
According to the second embodiment, since the plurality of pairs of claw portions 265 and 265 that can hold the retainer 260 in a rollable manner are provided, the rolling element 35 can be reliably held. Moreover, the retainer 260 provided with a pair of claw portions 265 and 265 is suitable as a retainer 260 for a so-called deep groove ball bearing.

  In addition, when the rolling bearing 230 is formed, the outer peripheral surface 262 of the projecting portion 264 that projects outward in the radial direction of the base portion 260a can be used as the retainer guide surface 262a. Furthermore, by forming the dynamic pressure groove 70 on the retainer guide surface 262a of the base portion 260a, the retainer guide surface 262a formed on the base portion 260a of the retainer 260 and the outer ring 31 are in high contact when the retainer 260 rotates. Contact with pressure can be suppressed. Therefore, since the wear of the retainer 260 can be suppressed, the durability of the retainer 260 can be ensured.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  In the first embodiment, the rolling bearing 30 of the tool 5 of the dental handpiece 1 has been described as an example. However, the application of the rolling bearings 30 and 230 of each embodiment is not limited to the tool 5 of the dental handpiece 1. For example, the rolling bearings 30 and 230 according to the embodiments may be applied as spindle motor bearings for rotating the disk of the information recording / reproducing apparatus, and the rolling bearings according to the embodiments may be used as bearings for the tool 5 of a machine tool that rotates at high speed. 30,230 may be applied.

  In each embodiment, the outer ring 31 is fixed and the inner ring 36 rotates, and the distance between the outer peripheral surfaces 62 and 262 of the retainers 60 and 260 and the inner peripheral surface 32 of the outer ring 31 is the inner peripheral surface of the retainers 60 and 260. The rolling bearings 30 and 230 of the so-called outer ring guide type, which are narrower than the distance between the 61 and 261 and the outer peripheral surface 37 of the inner ring 36, have been described as an example. In contrast, the inner ring 36 is fixed and the outer ring 31 rotates, and the distance between the inner peripheral surfaces 61 and 261 of the retainers 60 and 260 and the outer peripheral surface 37 of the inner ring 36 is the outer peripheral surface 62 of the retainers 60 and 260. , 262 and the inner ring surface 32 of the outer ring 31, the present invention may be applied to a so-called inner ring guide type rolling bearing that is narrower than the separation distance. In this case, since the outer ring rotates, a dynamic fluid pressure can be generated between the inner ring having a high relative rotational speed and the inner peripheral surface of the retainer by providing a dynamic pressure groove on the inner peripheral surface of the retainer. it can. Further, in this case, a dynamic pressure groove may be provided also on the outer peripheral surface of the retainer to generate fluid dynamic pressure between the outer ring and the outer peripheral surface of the retainer.

  In the retainer 260 of the second embodiment, an end portion on the other side (lower side in FIG. 8) of the base portion 260a is a protruding portion 264 that is formed to protrude outward in the radial direction. On the other hand, for example, without providing the overhang portion 264, the outer peripheral surface 262 of the base portion 260a is disposed close to the inner peripheral surface 32 of the outer ring 31, and the dynamic pressure groove 70 is provided on the outer peripheral surface 262 of the base portion 260a. It is good also as a structure.

FIG. 11 is an explanatory diagram of another shape of the dynamic pressure groove 70.
The dynamic pressure groove 70 of each embodiment is formed in a substantially V shape when viewed from the axial direction by the first side surface 71 and the second side surface 72, but the shape of the dynamic pressure groove 70 is different from that of each embodiment. There is no limit.
For example, as shown in FIG. 11, a dynamic pressure groove 70 is formed by a first side surface 71, a second side surface 72, and a bottom surface 73 that connects the first side surface 71 and the second side surface 72 and is orthogonal to the radial direction. May be. Also in this case, fluid dynamic pressure can be generated between the retainer guide surface 62a and the inner peripheral surface 32 (see FIG. 3) of the outer ring 31, so that the same effects as those of the embodiments can be obtained.

  In addition, it is possible to appropriately replace the components in the above-described embodiments with known components without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Dental handpiece 20 ... Ring body 31 ... Outer ring 35 ... Rolling body 36 ... Inner ring 60, 260 ... Retainer (retainer) 61, 261 ... Inner peripheral surface 62, 262 ... outer peripheral surface 62a, 262a ... retainer guide surface (cage guide surface) 70 ... (first) dynamic pressure groove 70a ... bottom 71 ... first side 72 ... Second side 75 ... (second) dynamic pressure groove 75a ... bottom 260a ... base portion 264 ... overhang portion 265 ... claw portion θ ... direction of rotation

Claims (6)

An annular cage that holds a plurality of rolling elements arranged in a ring having an outer ring and an inner ring arranged on the same axis in a circumferentially arranged state so as to freely roll.
At least one of the outer peripheral surface and the inner peripheral surface of the retainer is provided with a dynamic pressure groove that generates fluid dynamic pressure between the ring body and the retainer when the retainer rotates.
A plurality of the dynamic pressure grooves are formed along the axial direction of the cage and parallel to the circumferential direction ,
The dynamic pressure groove is
A first side surface disposed on the downstream side in the relative rotational direction of the ring body as viewed from the cage;
A second side surface formed continuously with the first side surface and disposed on the upstream side in the relative rotation direction of the ring body as viewed from the cage;
With
The first side surface is formed to have a larger area than the second side surface, and is formed along the circumferential direction than the second side surface when viewed from the axial direction.
The outer peripheral surface and the inner peripheral surface of the cage are provided with the first dynamic pressure groove and the second dynamic pressure groove, respectively.
The retainer, wherein the bottom portion of the first dynamic pressure groove and the bottom portion of the second dynamic pressure groove are formed at positions shifted in the circumferential direction . The cage according to claim 1,
An annular base,
A plurality of sets of claw portions that are erected from the base portion toward the one side in the axial direction, and capable of holding the rolling elements in a freely rollable manner;
With
The cage is characterized in that the dynamic pressure groove is formed in at least one of an inner peripheral surface and an outer peripheral surface of the base portion. The cage according to claim 2, wherein
The base portion includes a protruding portion formed to protrude on either the inner side or the outer side in the radial direction,
The cage, wherein the dynamic pressure groove is formed at least on a peripheral surface of the overhanging portion. A cage according to claim 1,
The rolling bearing according to claim 1, wherein the dynamic pressure groove is formed at least on a cage guide surface of the cage. The rolling bearing according to claim 4 ,
When the rolling bearing is used, if the relative rotation speed between the inner ring and the cage is higher than the relative rotation speed between the outer ring and the cage, the dynamic pressure groove is formed on the inner circumferential surface of the cage. When the relative rotational speed between the outer ring and the cage is higher than the relative rotational speed between the inner ring and the cage, the dynamic pressure groove is provided on the outer peripheral surface of the cage. Characteristic rolling bearing. A dental handpiece comprising the rolling bearing according to claim 5 .

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