JP2005257028A - Rolling bearing unit for swing arm and magnetic disk drive device - Google Patents

Abstract

To improve the mounting accuracy of a swing arm with an inexpensive structure.
A pair of ball bearings (13, 13) is provided between an inner peripheral surface of both ends of a shaft member (12a) and an outer peripheral surface of both ends of an outer cylinder (14a). A predetermined preload is applied to the pair of ball bearings 13, 13 by applying an axial load in a direction in which one of the pair of inner rings 16, 16 approaches the other inner ring 16. A screw hole 27 that does not penetrate in the axial direction is formed in the distal end surface of the shaft member 12a, and the top cover can be coupled and fixed to the shaft member 12a by a screw coupled to the screw hole 27. A fitting portion 30 having a male screw portion 31 formed on the outer peripheral surface is provided at the base end portion of the shaft member 12a, and the male screw portion 31 is screwed into a screw hole formed in the substrate portion and tightened, thereby tightening the shaft member 12a. Can be coupled and fixed to the substrate portion. A cylindrical portion constituting the base end portion of the swing arm is freely fitted and fixed to the outer cylinder 14a.
[Selection] Figure 1

Description

  The present invention relates to a swing arm rolling bearing unit and a magnetic disk, which are used to swingably displace a swing arm incorporated in a magnetic disk drive device such as a hard disk drive device (HDD) or a flexible disk drive device (FDD). The present invention relates to an improvement of a drive device.

  An HDD used as a storage device such as a computer has a structure as shown in FIGS. A hard disk drive device (HDD) 1 shown in FIGS. 8 to 9 includes a casing main body 2, an electric motor 4 mounted on a substrate section 3 that is a base portion constituting the casing main body 2, and a predetermined position on the hard disk 5. A head stack assembly (hereinafter referred to as “HSA”) 6 for writing a signal and reading the signal from an arbitrary position is provided. When used, the hard disk 5 is rotated at a high speed by the electric motor 4.

  The HSA 6 is a rolling bearing that rotatably supports a swing arm 7 having a magnetic head 25 at a distal end portion and a cylindrical portion 8 constituting a base end portion of the swing arm 7 with respect to a part of the substrate portion 3. A unit 9 and a voice coil motor (BCM) 10 that swings and displaces the swing arm 7 around the central axis of the cylindrical portion 8 are provided. Further, as shown in detail in FIG. 10, the rolling bearing unit 9 includes a shaft member 12 having a through-hole 11 penetrating in the axial direction at the center thereof, a pair of ball bearings 13 and 13, and an outer cylinder. 14. Of these, the shaft member 12 corresponds to the inner member recited in the claims. Each of the ball bearings 13 and 13 includes an inner ring 16 having a deep groove type inner ring raceway 15 on an outer peripheral surface, an outer ring 18 having a deep groove type outer ring raceway 17 on an inner peripheral surface, and the inner ring raceway 15 and the outer ring raceway 17. And a plurality of balls 19, 19 each of which is a rolling element. Further, an annular protrusion 20 protruding radially inward is formed at an axially intermediate portion of the inner peripheral surface of the outer cylinder 14.

  The pair of ball bearings 13, 13 as described above has both end portions in the axial direction of the outer cylinder 14 in a state in which one end surface in the axial direction of each outer ring 18, 18 abuts on both side surfaces of the annular protrusion 20. These outer rings 18 and 18 are internally fitted and fixed by adhesion. Further, of the pair of ball bearings 13, 13, one axial end surface (the lower end surface in FIG. 10) of the inner ring 16 constituting one (lower in FIG. 10) of the ball bearing 13 is the base of the shaft member 12. The inner ring 16 is attached to a portion near the base end of the shaft member 12 in a state where it is abutted against one side surface (upper side surface in FIG. 10) of the flange portion 21 having an outward flange shape formed at the end portion (lower end portion in FIG. 10). The outer fitting is fixed by bonding. On the other hand, of the pair of ball bearings 13, 13, the inner ring 16 constituting the other (upper side in FIG. 10) is located near the tip of the shaft member 12 (upper end portion in FIG. 10). It is fitted externally so that it can be displaced in the axial direction.

  In order to support the base end portion of the swing arm 7 (FIGS. 8 and 9) with respect to a part of the substrate portion 3 by the rolling bearing unit 9 as described above, the inner surface ( 9 and 10), the flange portion 21 of the shaft member 12 is placed on the peripheral edge portion of the screw hole 22 formed in a part of the substrate portion 3. Then, a screw 24 inserted through a part of the top cover 23 provided on the distal end side (the upper end side in FIG. 10) of the shaft member 12 and the through hole 11 formed in the shaft member 12 is inserted into the screw hole 22. The shaft member 12 and the top cover 23 are coupled and fixed to the substrate portion 3 by screwing and tightening. In addition, a cylindrical portion 8 provided at the base end portion of the swing arm 7 is externally fitted and fixed around the outer cylinder 14. Furthermore, in the state where the inner ring 16 constituting the other ball bearing 13 of the pair of ball bearings 13 and 13 is pressed in a direction approaching the inner ring 16 constituting the one ball bearing 13, the shaft member A predetermined preload is applied to the pair of ball bearings 13 and 13 by being fixed to the outer peripheral surface near the tip of 12 by adhesion. In order to apply a predetermined preload to the ball bearings 13, 13, the operation of pressing the inner rings 16, 16 toward each other is performed by pressing the shaft member 12 between the inner surface of the substrate portion 3 and the top cover 23. This is performed before being sandwiched between one surface (the lower surface in FIGS. 9 and 10).

  In the assembled state as described above, the magnetic head 25 (FIGS. 8 and 9) supported on the tip of the swing arm 7 moves along with the hard disk 5 (FIGS. 8 and 9) as the swing arm 7 swings. The signal is read and written while moving so as to follow the surface while being close to the surface.

  Patent Document 1 describes that in addition to the rolling bearing unit 9 shown in FIG. 10, the rolling bearing units 9 a and 9 b shown in FIGS. 11 to 12 can also be used for the swing support portion of the swing arm 7. ing. In the case of the structure shown in FIG. 11, the annular protrusion 20 (FIG. 10) is not formed on the inner peripheral surface of the outer cylinder 14. Instead, a spacer 26 is fitted in an intermediate portion in the axial direction of the inner peripheral surface of the outer cylinder 14. The axial end surfaces of the outer rings 18, 18 constituting the pair of ball bearings 13, 13 are abutted against both axial end surfaces of the spacer 26. In the case of the structure shown in FIG. 12, in the structure shown in FIG. 11, the outer cylinder 14 is omitted, and the outer rings 18 and 18 and the spacer 26 constituting the pair of ball bearings 13 and 13 are It can be directly fitted and fixed to the cylindrical portion 8 (FIGS. 8 and 9) provided at the base end portion of the swing arm 7 (FIGS. 8 and 9).

  In addition to the structure shown in FIGS. 10 to 12 described above, a combination bearing in which a pair of ball bearings are combined so as to overlap each other and a preload is applied to the swing bearing unit 7 for swing arm swing. It may be used for the support part. In the case of such a structure, since the inner ring and the outer ring constituting the pair of ball bearings are in contact with each other in a state where a preload is applied, the preload amount to be applied is uniquely determined by the dimensions of these ball bearings. The preload amount cannot be adjusted easily. Further, when such a structure is used for the swing support portion of the swing arm and when it is required to change the preload amount, it is necessary to change the design of each ball bearing. For this reason, it is practically difficult to adopt this structure.

  In the case of the conventional structure shown in FIGS. 10 to 12 described above, a through-hole penetrating in the axial direction for inserting a screw 24 in the center of the shaft member 12 in order to couple and fix the top cover 23 to the shaft member 12. A hole 11 is formed. Further, a flange portion 21 is formed at the base end portion of the shaft member 12 so as to abut against the inner surface of the substrate portion 3 of the casing 2. In the case of such a conventional structure, the mounting accuracy of the base end portion of the swing arm 7 (FIGS. 8 to 9) with respect to the substrate portion 3 is such that one side surface of the flange portion 21 that contacts the substrate portion 3 (FIG. 10). ˜12) and the right angle between the outer peripheral surface of the shaft member 12 and the portion where the inner rings 16, 16 are fitted, the side surface of the flange 21 and the inner surface of the through hole 11 It is also affected by the dimensional accuracy and shape accuracy. For example, if the perpendicularity between one side surface of the flange portion 21 and the inner surface of the through hole 11 is poor, the swing arm 7 is easily tilted when the swing arm 7 is attached. However, it is troublesome to improve the squareness of the inner surface of one side surface of the flange portion 21 and the through-hole 11, which causes a cost increase.

In recent years, portable computers have been reduced in size and thickness, and accordingly, it is required to reduce the size and thickness of magnetic disk drive devices such as HDDs. On the other hand, the miniaturization of the HDD can be dealt with by reducing the diameter of the hard disk from 3.5 inches to 2.5 inches, and further to 1.8 inches. Further, the rolling bearing incorporated in the HSA 6 can be dealt with by reducing the diameters of the inner ring and the outer ring. On the other hand, in order to reduce the thickness of the HDD, it is necessary to reduce the axial dimension of the swing support portion of the swing arm 7. The axial dimension of the swing support portion can be reduced to some extent by selecting a small axial dimension for each rolling bearing. However, in recent years, there has been a demand for ultra-thin HDDs, and in order to meet this demand, there is a limit to simply selecting a rolling bearing with a small axial dimension.
As prior art documents related to the present invention, there is Patent Document 2 in addition to Patent Document 1.

Japanese Patent Laid-Open No. 10-318255 JP 2003-194050 A

  In view of the above-described circumstances, the swing arm rolling bearing unit and the magnetic disk drive device of the present invention have an inexpensive structure, improve the mounting accuracy of the swing arm, and reduce the size and thickness of the magnetic disk drive device. Invented accordingly.

  Of the rolling bearing unit for swing arm and the magnetic disk drive device of the present invention, the rolling bearing unit for swing arm described in claim 1 is used in the same manner as the conventional rolling bearing unit for swing arm described above. An inner member that is fixed to a base that does not rotate sometimes, an outer cylinder that is disposed around the inner member and that can be fitted and supported on the outer peripheral surface of the base end of the swing arm, and the outer cylinder and the inner member Each outer ring is fixed at two axial positions on the inner peripheral surface of the outer cylinder, and each inner ring is fixed at two axial positions on the outer peripheral surface of the inner member so that they can be relatively rotated. A pair of rolling bearings. A preload is applied to the pair of rolling bearings by applying an axial load in a direction approaching the inner rings constituting the pair of rolling bearings.

  In particular, in the rolling arm unit for swing arm of the present invention, a screw hole formed in a state where it does not penetrate in the axial direction on one end surface opposite to the side fixed to the base portion of the inner member; An outward flange-shaped flange formed on a part of the outer peripheral surface of the inner member, and the screw hole formed on the inner side formed on the outer peripheral surface of the inner member near the other end on the base side. A fitting portion for fitting to the base portion. And the inner ring | wheel which comprises one rolling bearing of said 1 pair of rolling bearings is abutted on the said collar part.

  According to a seventh aspect of the present invention, there is provided a magnetic disk drive device according to the present invention, comprising the above-mentioned swing arm rolling bearing unit, a swing arm fixed to the outer peripheral surface of the outer cylinder, and a base portion to which an inner member is fixed. Use a magnetic disk with a diameter of 5 inches or less.

  In the case of the rolling bearing unit for a swing arm and the magnetic disk drive device of the present invention configured as described above, a screw that does not penetrate in the axial direction on one end surface opposite to the side fixed to the base portion of the inner member. A hole is formed. For this reason, the top cover can be coupled and fixed to the inner member by screwing a screw inserted through a part of the top cover into the screw hole and further tightening. Moreover, in the case of the present invention, a fitting portion for fitting to the base portion is formed on the outer peripheral surface of the inner member near the other end on the base side. The outer peripheral surface can be easily processed so as to be coaxial with the other portion on which the inner ring is fitted on the outer peripheral surface of the inner member. For this reason, a through-hole penetrating in the axial direction is formed in the center of the inner member, and the inner member is fixed to the base by coupling a screw inserted through the through-hole to a screw hole formed in the base. The mounting accuracy of the swing support portion of the swing arm can be made higher than in the case of the conventional structure. That is, in the case of such a conventional structure, this mounting accuracy is affected by the dimensional accuracy and shape accuracy of the inner surface of the through hole and the side surface of the flange formed on the base side of the outer peripheral surface of the inner member. Because of the large size, it is difficult to increase the mounting accuracy at low cost. On the other hand, in the case of the present invention, the accuracy of the shape and dimensions of the outer peripheral surface of the fitting portion can be increased without increasing the cost, and the side surface of the collar portion formed on the inner member is used as the base portion. Even in the case of abutment, the accuracy of the shape and dimensions of the side surface does not greatly affect the accuracy of mounting the inner member. For this reason, the mounting accuracy of the swing support portion of the swing arm can be increased at low cost.

  In the case of the present invention, since the screw hole is not formed inside the fitting portion, the rigidity of the fitting portion can be sufficiently increased. For this reason, the mounting accuracy of the swing arm can be further increased. Furthermore, since the magnetic disk drive apparatus of the present invention uses a magnetic disk having a diameter of 2.5 inches or less, the mounting accuracy of the swing support portion of the swing arm can be increased by employing the configuration of the present invention. The effect said is remarkable.

When carrying out the present invention, preferably, as described in claim 2, each rolling bearing is an angular ball bearing in which at least one of the inner ring and the outer ring is a shoulder ring. .
According to this preferred configuration, even when the ball diameter of each ball bearing and the PCD (pitch circle diameter) of the plurality of balls are the same, as compared with the case where each rolling bearing is a deep groove type ball bearing, more balls are used. Can be assembled. For this reason, the bearing rigidity can be improved.

More preferably, as described in claim 3, a male screw portion for screwing into a screw hole formed in the base portion is formed in the fitting portion of the inner member, and the flange portion is formed on the inner member. The part near the other end is formed at a part deviated to one end side from the male screw part. The screw hole is prevented from reaching at least the same position as the male screw portion in the axial direction of the inner member.
According to this more preferable configuration, the inner member can be easily coupled and fixed to the base.

Furthermore, more preferably, as described in claim 4, of the inner rings constituting at least one of the pair of rolling bearings, the inner portion in the axial direction with respect to the center of the rolling element constituting the rolling bearing. Of the outer ring constituting the rolling bearing is made smaller than the axial dimension of the inner part in the axial direction with respect to the center of the rolling element. More preferably, in addition to such a configuration, among the inner rings constituting at least one of the rolling bearings, the axial dimension of the outer portion in the axial direction with respect to the center of the rolling element constituting the rolling bearing is configured as the rolling bearing. Of the outer ring, the axial dimension of the outer portion in the axial direction is made smaller than the center of the rolling element.
According to this more preferable configuration, it is possible to form an axial gap between the inner rings facing each other in a state where the axial end surfaces of the outer rings constituting the pair of rolling bearings are in contact with each other. For this reason, this gap can be used to apply an appropriate preload to the pair of rolling bearings, and the preload can be changed by changing the size of the gap without changing the design of each rolling bearing. Easy to adjust. In addition, in order to bring the axial end surfaces of the pair of outer rings into contact with each other, unlike the conventional structure described above, preload is applied to each rolling bearing without providing an annular protrusion or spacer between the pair of outer rings. It can be granted. For this reason, the total axial length of the rolling bearing portion can be reduced, the axial dimension of the swing support portion of the swing arm is reduced, and the magnetic disk drive device can be easily made extremely thin. Further, according to a more preferable configuration, the total axial length of the rolling bearing portion including the inner member can be further reduced.

More preferably, as described in claim 5, a fixed position preload is applied to a pair of rolling bearings so as to form a combination on the back surface.
According to this more preferable configuration, the outer cylinder can be hardly inclined with respect to the inner member, and the moment rigidity of the outer cylinder and the swing support portion of the swing arm fixed to the outer cylinder can be increased.

More preferably, as described in claim 6, the inner member is made of any one of austenitic stainless steel, martensitic stainless steel, and aluminum alloy.
According to this more preferable configuration, it is possible to improve the performance of a magnetic disk drive device incorporating a swing arm rolling bearing unit. First, when the inner member is made of either austenitic stainless steel or martensitic stainless steel, the corrosion resistance of the inner member and the magnetic disk device can be increased. Further, when the inner member is made of an aluminum alloy, the inner member and the magnetic disk device can be reduced in weight.

  FIG. 1 shows Embodiment 1 of the present invention corresponding to claims 1 to 3 and 5 to 7. The rolling bearing unit 9c of the present embodiment includes a shaft member 12a that is an inner member, an outer cylinder 14a, and a pair of ball bearings 13 and 13. Of these, the shaft member 12a is made of an austenitic stainless steel such as SUS303 or SUS306, a martensitic stainless steel such as SUS440C, an aluminum alloy such as A2017-74, and the like on the tip surface (upper end surface in FIG. 1). A screw hole 27 that does not penetrate in the axial direction is formed. A through hole penetrating in the axial direction is not formed in the shaft member 12a. Further, an outward flange-like flange portion 28 is formed on the outer peripheral surface of the shaft member 12a near the base end (portion near the lower end in FIG. 1), and at the base end portion of the shaft member 12a, the flange 28 A small-diameter portion 29 having a smaller diameter and a fitting portion 30 having a larger diameter than the small-diameter portion 29 are provided in order from the side of the flange portion 28 at a portion that is distant to the proximal end side. Further, a male thread portion 31 is formed on the outer peripheral surface of the fitting portion 30. With respect to the axial direction of the shaft member 12 a, the screw hole 27 does not reach the same position as the male screw portion 31 and the flange portion 28.

  Around such a shaft member 12a, an outer cylinder 14a formed in a cylindrical shape as a whole is arranged. An outward flange-like flange portion 32 is formed on the outer peripheral surface of one axial end portion (upper end portion in FIG. 1) of the outer cylinder 14a, and the annular protrusion 20 is formed on the inner peripheral surface of the intermediate portion.

  Each of the pair of ball bearings 13 and 13 includes an inner ring 16 having a deep groove or angular inner ring raceway 15 on the outer peripheral surface, and an outer ring 18 having a deep groove type or angular outer ring raceway 17 on the inner peripheral surface. A plurality of balls 19, 19 provided between the inner ring raceway 15 and the outer ring raceway 17 so as to roll freely. The plurality of balls 19 and 19 are held in a freely rollable manner by a cage not shown. Although not shown, a contact-type or non-contact-type seal ring is provided between the end outer peripheral surface of the inner ring 16 and the end inner peripheral surface of the outer ring 18 as necessary.

  The pair of ball bearings 13 and 13 as described above have the outer rings 18 and 18 fitted and fixed to the outer cylinder 14a by adhesion, and one end surfaces in the axial direction of the outer rings 18 and 18 are fixed to the outer cylinder 14a. It abuts against both axial side surfaces of the annular projection 20 formed on the inner peripheral surface of the cylinder 14a. One of the pair of inner rings 16, 16 (the lower side in FIG. 1) has one inner ring 16 on one side surface (upper side surface in FIG. 1) of the flange portion 28 formed near the base end of the shaft member 12a. I'm hitting it. In addition, the other inner ring 18 of the pair of inner rings 16, 16 is pressed in a direction approaching the one inner ring 18 (an axial load is applied). In this state, the inner rings 16, 16 are externally fitted and fixed to both ends in the axial direction of the shaft member 12a. With this configuration, a fixed position preload is applied to the pair of ball bearings 13 and 13 so as to form a back surface combination.

  With the rolling bearing unit 9c of the present example configured as described above, the base end portion of the swing arm 7 (see FIGS. 8 and 9) is made part of the base plate portion 3 (see FIGS. 8 and 9) of the casing 2. In order to swingably support, the male screw portion 31 formed on the outer peripheral surface of the fitting portion 30 provided at the base end portion of the shaft member 12 a is screwed into the screw hole 22 formed in a part of the substrate portion 3. And tighten further. With this configuration, the fitting portion 30 is fitted into the screw hole 22 and the shaft member 12 a is coupled and fixed to the substrate portion 3.

  Further, the top cover 23 (see FIG. 10) is overlaid on the distal end surface of the shaft member 12a, and the male screw portion of the screw 24 (see FIG. 10) through which a part of the top cover 23 is inserted is connected to the shaft member 12a. The screw hole 27 formed on the tip surface is screwed and further tightened. Thus, the top cover 23 is coupled and fixed to the shaft member 12 a and the substrate portion 3. Moreover, the cylinder part 8 (refer FIG. 8-9) which comprises the base end part of the said swing arm 7 is externally fixed by adhesion | attachment to the said outer cylinder 14a. The structure of the HDD other than the rolling bearing unit 9c is the same as that of the conventional structure shown in FIGS. Further, when using the HDD constructed by incorporating the rolling bearing unit 9c, the hard disk 5 (see FIGS. 8 and 9) having a diameter of 2.5 inches or less is used.

  In the case of the rolling bearing unit for a swing arm and the magnetic disk drive device of the present invention configured as described above, the shaft member 12a is penetrated in the axial direction on the tip surface opposite to the side fixed to the substrate portion 3. A screw hole 27 that is not to be formed is formed. For this reason, the top cover 23 is fixedly coupled to the shaft member 12a by screwing the male screw portion of the screw 24 through which a part of the top cover 23 (see FIG. 10) is inserted into the screw hole 27 and further tightening. it can.

  Moreover, in the case of the present invention, the shaft member 12a is fitted into a screw hole 22 (see FIG. 10) formed in a part of the substrate portion 3 in a portion near the base end on the substrate portion 3 side on the outer peripheral surface of the shaft member 12a. The fitting part 30 for doing is formed. For this reason, the outer peripheral surface of this fitting part 30 can be easily processed so that it may become coaxial with the other part which fits the inner ring | wheels 16 and 16 in the outer peripheral surface of the said shaft member 12a. Therefore, as shown in FIG. 10 described above, the through hole 11 penetrating in the axial direction is formed in the central portion of the shaft member 12, and the screw hole 22 formed in the substrate portion 3 with the screw 24 inserted through the through hole 11. As a result, the mounting accuracy of the swing support portion of the swing arm 7 can be made higher than in the case of the above-described conventional structure in which the shaft member 12 is connected and fixed to the substrate portion 3. That is, in the case of such a conventional structure, this mounting accuracy is the perpendicularity between the inner surface of the through hole 11 and the side surface of the flange portion 21 formed on the substrate portion 3 side of the outer peripheral surface of the shaft member 12. Since it is greatly affected by the dimensional accuracy and shape accuracy between the inner surface and the side surface, it is difficult to increase the mounting accuracy at low cost. On the other hand, in the case of the present invention, if the coaxiality between the outer peripheral surface of the fitting portion 30 and the portion where the inner rings 16, 16 are fitted on the outer peripheral surface of the shaft member 12a is good. good. In order to improve the coaxiality, the outer peripheral surface of the fitting portion 30 may be processed with reference to the fitting portion of the shaft member 12a. Such processing can be easily performed. For this reason, the accuracy of the shape and dimensions of the outer peripheral surface of the fitting portion 30 can be increased without increasing the cost. Even when one side surface of the flange portion 28 formed on the shaft member 12a is abutted against the inner surface of the substrate portion 3, the mounting accuracy is greatly affected by the accuracy of the shape and dimensions of the one side surface of the flange portion 28. Absent. Further, since the screw hole 27 formed in the shaft member 12a is used only for attaching the top cover 23, even if the perpendicularity between the screw hole 27 and one side surface of the flange portion 28 is not so good. The mounting accuracy is not affected. For this reason, the mounting accuracy of the swing support portion of the swing arm 7 can be increased at low cost. Furthermore, since the magnetic disk drive apparatus of the present invention uses the hard disk 5 having a diameter of 2.5 inches or less, the mounting accuracy of the swing support portion of the swing arm 7 is increased by adopting the configuration of the present invention. The effect that you can do is remarkable.

  Further, when each ball bearing 13, 13 constituting the rolling bearing unit 9 c is an angular type in which at least one of the inner ring 16 and the outer ring 18 is a shoulder drop race ring, each ball bearing 13 , 13 can be assembled with a large number of balls 19, 19 even when the ball diameters of the ball bearings 13, 13 and the PCDs of the balls 19, 19 are the same. For this reason, the bearing rigidity can be improved.

  Furthermore, in the case of the present embodiment, a male screw portion 31 is formed in the fitting portion 30 provided at the base end portion of the shaft member 12a, and this male screw portion 31 is screwed into the screw hole 22 formed in the substrate portion 3. The shaft member 12a is coupled and fixed to the substrate portion 3 by further tightening. Further, the screw hole 22 is prevented from reaching the same position as the male screw portion 31 and the flange portion 28 with respect to the axial direction of the shaft member 12a. For this reason, this shaft member 12a can be easily coupled and fixed to the substrate portion 3. Further, since the rigidity of the fitting portion 30 can be increased, the mounting accuracy of the swing arm 7 can be further improved.

  Further, in the case of the present embodiment, a fixed position preload is applied to the pair of ball bearings 13 and 13 so as to be a rear combination. For this reason, the outer cylinder 14a can be hardly inclined with respect to the shaft member 12a, and the moment rigidity of the outer cylinder 14a and the swing support portion of the swing arm 7 fixed to the outer cylinder 14a can be increased.

  Further, when the shaft member 12a is made of any one of austenitic stainless steel, martensitic stainless steel, and aluminum alloy, the performance of the HDD incorporating the rolling bearing unit 9c can be improved. For example, when the shaft member 12a is made of either austenitic stainless steel or martensitic stainless steel, the corrosion resistance of the shaft member 12a and the HDD can be increased. Further, when the shaft member 12a is made of an aluminum alloy, the weight of the shaft member 12a and the HDD can be reduced.

Next, FIG. 2 shows Embodiment 2 of the present invention, which also corresponds to claims 1 to 3 and 5 to 7. In the case of the rolling bearing unit 9d of the present embodiment, the outer cylinder 14a (see FIG. 1) is omitted in the structure of the first embodiment described above. A cylindrical spacer 26 is sandwiched between the outer rings 18 and 18 constituting the pair of ball bearings 13 and 13. The outer rings 18 and 18 and the spacer 26 are directly fitted and fixed to the cylindrical portion 8 (see FIGS. 8 and 9) that constitutes the base end portion of the swing arm 7. In the case of this embodiment, the diameter of the swing support portion of the swing arm 7 can be made smaller by the amount that the outer cylinder 14a can be omitted, and the HDD incorporating the rolling bearing unit 9d can be easily downsized.
Since other configurations and operations are the same as those in the first embodiment described above, the same reference numerals are given to the equivalent parts, and duplicate descriptions are omitted.

  Next, FIG. 3 shows Embodiment 3 of the present invention, which also corresponds to claims 1 to 3 and 5 to 7. In the case of the rolling bearing unit 9e of the present embodiment, the flange portion 28a having an outward flange shape is formed on the outer peripheral surface of the distal end portion of the shaft member 12b in the structure of the first embodiment shown in FIG. The flange portion 28 (see FIGS. 1 and 2) is not formed on the outer peripheral surface near the end. Of the pair of ball bearings 13 and 13, one end surface in the axial direction (upper end surface in FIG. 3) of the inner ring 16 constituting the other (upper side in FIG. 3) ball bearing 13 is used as one side surface of the flange portion 28a. (Bottom side of FIG. 3).

In the case of this embodiment, the inner ring 16 constituting one of the ball bearings 13 (downward in FIG. 3) of the pair of ball bearings 13, 13 is replaced with the inner ring 16 constituting the other ball bearing 13. A predetermined preload is applied to the pair of ball bearings 13, 13 by pressing in the direction approaching.
Since other configurations and operations are the same as those of the first embodiment shown in FIG. 1 described above, the same reference numerals are given to the equivalent parts, and duplicate descriptions are omitted.

Next, FIG. 4 shows Embodiment 4 of the present invention, which also corresponds to claims 1 to 3 and 5 to 7. In the case of the rolling bearing unit 9f of the present embodiment, it has a structure in which the second embodiment shown in FIG. 2 is combined with the third embodiment shown in FIG. That is, in the case of the present embodiment, the flange portion 28a having an outward flange shape is formed on the outer peripheral surface of the tip end portion of the shaft member 12b with the structure of the second embodiment shown in FIG. Of the pair of ball bearings 13, 13, one end surface in the axial direction (upper end surface in FIG. 4) of the inner ring 16 constituting the other (upper side in FIG. 4) is used as one side surface of the flange portion 28 a. (Bottom side of FIG. 4).
Since other configurations and operations are the same as those of the second embodiment shown in FIG. 2 and the third embodiment shown in FIG. 3, the same parts are denoted by the same reference numerals and are duplicated. The description to be omitted is omitted.

Next, FIG. 5 shows Embodiment 5 of the present invention corresponding to all claims. In the case of the rolling bearing unit 9g of the present embodiment, of the inner ring 16a, 16a constituting the pair of ball bearings 13a, 13a in the structure of the first embodiment shown in FIG. the axial dimension L _a in the axial direction both side portions with respect to the center of the balls 19 and 19 constituting the 13a, the L _b, both have small. Therefore, respective axial dimension L _a, L _b is, among the outer ring 18, 18 constituting the ball bearing 13a, a 13a, axially with respect to the center of the balls 19 and 19 constituting the ball bearing 13, 13 It becomes smaller than the axial dimensions L _a ′ and L _b ′ of both side portions (L _a <L _a ′, L _b <L _b ′). And the axial direction one end surfaces of the outer ring | wheels 18 and 18 which comprise said 1 pair of ball bearings 13a and 13a are mutually abutted. Of the inner rings 16a and 16a constituting the pair of ball bearings 13a and 13a, the other end surface in the axial direction of one (downward in FIG. 5) of the inner ring 16a is formed in a portion near the base end of the shaft member 12a. It abuts against one side surface of the portion 28 (the upper side surface in FIG. 5).

In the case of this embodiment configured in this way, the inner rings 16a, 16a facing each other are in contact with each other in the state where the axial end surfaces of the outer rings 18, 18 constituting the pair of ball bearings 13a, 13a are in contact with each other. In addition, the axial gap 33 can be formed. For this reason, it is possible to apply an appropriate preload to the pair of ball bearings 13 and 13 using the gap 33, and without changing the design of the ball bearings 13 and 13, Preload can be easily adjusted by changing the size. Moreover, in order to bring the axial end surfaces of the pair of outer rings 18 and 18 into contact with each other, the conventional structure shown in FIGS. 10 to 12 described above, and the case of the first to fourth embodiments shown in FIGS. Differently, it is possible to apply a preload to each of the ball bearings 13a and 13a without providing the annular protrusion 20 and the spacer 26 between the pair of outer rings 18 and 18. For this reason, the total axial length of the rolling bearing unit 9g can be reduced. Therefore, the axial dimension of the swing support portion of the swing arm 7 (see FIGS. 8 and 9) is reduced, and it becomes easy to achieve a very thin HDD. In the case of the present embodiment, the axial dimension L _b of the inner part of each inner ring 16a, 16a in the axial direction is made smaller than the axial dimension L _b ′ of the inner part of each outer ring 18, 18 in the axial direction (L _b <L _b is smaller than ') as well, the axial dimension L _a of the axial outer portion of the inner races 16a, 16a axially outer portion each outer ring axial dimension L _a of 18, 18' (L _a <L _a ′). For this reason, the total axial length of the rolling bearing unit 9g including the shaft member 12a can be further reduced.
Since other configurations and operations are the same as those of the first embodiment shown in FIG. 1 described above, the same reference numerals are given to the equivalent parts, and duplicate descriptions are omitted.

Next, FIG. 6 shows a rolling bearing unit 9h according to a sixth embodiment of the present invention, which also corresponds to all claims. In the case of the present embodiment, only the inner ring 16a constituting one ball bearing 13a (downward in FIG. 6) of the pair of ball bearings 13 and 13a in the structure of the first embodiment shown in FIG. in, and the axial dimension L _a in the axial direction both side portions with respect to the center of the balls 19 and 19 constituting the one of the ball bearing 13a, the L _b, both small. In this embodiment, the effect is inferior to that of the embodiment 5 shown in FIG. 5 described above, but the total length in the axial direction of the rolling bearing unit 9h including the shaft member 12a can be reduced.
Other configurations and operations are the same as those of the first embodiment shown in FIG. 1 and the fifth embodiment shown in FIG. The description to be omitted is omitted.

Next, FIG. 7 shows Embodiment 7 of the present invention, which also corresponds to all the claims. In the case of the present embodiment, only the inner ring 16a constituting the other (upper side in FIG. 6) of the pair of ball bearings 13 and 13a in the structure of the first embodiment shown in FIG. 1 is used. in, and the axial dimension L _a in the axial direction both side portions with respect to the center of the balls 19 and 19 constituting the other of the ball bearing 13a, the L _b, both small. Even in this embodiment, the effect is inferior to that of the embodiment 5 shown in FIG. 5, but the total length in the axial direction of the rolling bearing unit 9i including the shaft member 12a can be reduced.
Since other configurations and operations are the same as those in the first and fifth embodiments shown in FIGS. 1 and 5 described above, the same parts are denoted by the same reference numerals, and redundant description is omitted.

  In addition, although illustration is abbreviate | omitted, the structure of either of the structures of Examples 2-4 shown in above-mentioned FIGS. 2-4 and the structure of Examples 5-7 shown in above-mentioned FIGS. Any of these structures can be combined. For example, each of the balls constituting the ball bearings 13 and 13 among the inner rings 16 and 16 constituting the ball bearings 13 and 13 in the structure of any one of the embodiments 2 to 4 shown in FIGS. The axial dimensions of both side portions in the axial direction with respect to the centers of the balls 19 and 19 are the axes with respect to the centers of the balls 19 and 19 constituting the ball bearings 13 and 13 among the outer rings 18 and 18 constituting the ball bearings 13 and 13. Make it smaller than the axial dimension of both side parts. Also in the case of such a configuration, the total axial length of the rolling bearing units 9d to 9f can be reduced as in the case of the fifth embodiment shown in FIG.

  Also, the inner ring 16 constituting one of the ball bearings 13 on the side provided with the fitting portion 30 of the pair of ball bearings 13 and 13 in the structures of the embodiments 2 to 4 shown in FIGS. Only (or only the inner ring 16 constituting the other ball bearing 13 on the side opposite to the fitting portion 30), and the center of each ball 19, 19 constituting this one ball bearing 13 (or the other ball bearing 13). The axial dimensions of both side portions in the axial direction are set so that each of the ball bearings 13 (or the other ball bearing 13) of the outer ring 18 constituting the one ball bearing 13 (or the other ball bearing 13) constitutes one ball bearing 13 (or the other ball bearing 13). It can also be made smaller than the axial dimension of both sides in the axial direction with respect to the center of the balls 19 and 19. Even in such a configuration, the effect is inferior to that in the case of the fifth embodiment shown in FIG. 5, but the same as in the sixth embodiment shown in FIG. 6 or the seventh embodiment shown in FIG. Moreover, the axial total length of the rolling bearing units 9d to 9f can be reduced.

  In addition, in the case of each Example mentioned above, it demonstrated about the case where the external thread part 31 was formed in the outer peripheral surface of the fitting part 30 of the shaft members 12a and 12b which are inner members. However, the present invention is not limited to such a structure. For example, the fitting portion 30 is fitted into a circular hole formed in a part of the substrate portion 3 with the outer peripheral surface of the fitting portion 30 as a simple cylindrical surface and having the inner peripheral surface as a simple cylindrical surface. It can also be fixed. Also in this case, it is possible to easily process the outer peripheral surface of the fitting portion 30 coaxially with other portions on the outer peripheral surfaces of the shaft members 12a and 12b that externally fit the inner rings 16 and 16a. Therefore, the mounting accuracy of the swing support portion of the swing arm 7 (see FIGS. 8 and 9) can be increased with an inexpensive structure.

Sectional drawing which shows the rolling bearing unit of Example 1 of this invention. The figure similar to FIG. 1 which shows the same Example 2. FIG. The figure similar to FIG. 1 which shows the same Example 3. FIG. The figure similar to FIG. 1 which shows the same Example 4. FIG. The figure similar to FIG. 1 which shows the same Example 5. FIG. The figure similar to FIG. 1 which shows the same Example 6. FIG. The figure similar to FIG. 1 which shows the same Example 7. FIG. The figure which shows one example of HDD which incorporated the swing arm supported by the rolling bearing unit used as the object of this invention in the state which removed the top cover. AA sectional drawing of FIG. The partial expanded sectional view which abbreviate | omits one part and shows the state which integrated the rolling bearing unit of the 1st example of the conventional structure in the rocking | fluctuation support part of the swing arm shown in FIG. Sectional drawing which shows the rolling bearing unit of the 2nd example of conventional structure. Sectional drawing which shows the rolling bearing unit of the 3rd example of conventional structure.

Explanation of symbols

1 Hard disk drive (HDD)
2 Casing body 3 Substrate 4 Electric motor 5 Hard disk 6 Head stack assembly (HSA)
DESCRIPTION OF SYMBOLS 7 Swing arm 8 Cylindrical part 9, 9a-9i Rolling bearing unit 10 Voice coil motor 11 Through-hole 12, 12a, 12b Shaft member 13, 13a Ball bearing 14, 14a Outer cylinder 15 Inner ring track 16, 16a Inner ring 17 Outer ring track 18 Outer ring 19 ball 20 annular projection 21 flange 22 screw hole 23 top cover 24 screw 25 magnetic head 26 spacer 27 screw hole 28, 28a flange 29 small diameter part 30 fitting part 31 male thread part 32 flange part 33 gap

Claims (7)

  An inner member that is fixed to a base that does not rotate when in use, an outer cylinder that is disposed around the inner member and that can be fitted and supported on the outer peripheral surface of the base end of the swing arm, and the outer cylinder and the inner member The outer rings are fixed at two axial positions on the inner peripheral surface of the outer cylinder, and the inner rings are fixed at two axial positions on the outer peripheral surface of the inner member. A swing arm rolling bearing provided with a pair of rolling bearings and applying an axial load in a direction approaching each other to the inner rings constituting the pair of rolling bearings, thereby applying a preload to the pair of rolling bearings. In the unit, a screw hole formed in a state where the inner member does not penetrate in the axial direction on one end surface opposite to the side fixed to the base portion, and a part of the outer peripheral surface of the inner member. Formed on the outer flange surface of the inner member and the other end of the inner member near the other end, which is closer to the other end, where the screw hole is not formed on the inner side. A swing arm rolling bearing unit comprising a fitting portion, wherein an inner ring constituting one of the pair of rolling bearings is abutted against the flange portion.   The rolling bearing unit for a swing arm according to claim 1, wherein each rolling bearing is an angular ball bearing in which at least one of the inner ring and the outer ring is a shoulder ring.   A male screw part for screwing into a screw hole formed in the base part is formed in the fitting part of the inner member, and the flange part is disengaged to one end side from the male screw part near the other end of the inner member. 3. The swing arm rolling bearing unit according to claim 1, wherein the screw hole does not reach at least the same position as the male screw portion in the axial direction of the inner member.   Of the inner ring constituting at least one of the pair of rolling bearings, the axial dimension of the inner portion in the axial direction with respect to the center of the rolling element constituting the rolling bearing is defined as the outer ring constituting the rolling bearing. The rolling bearing unit for a swing arm according to any one of claims 1 to 3, wherein the rolling bearing unit is smaller than the axial dimension of the inner part in the axial direction with respect to the center of the rolling element.   The rolling bearing unit for a swing arm according to any one of claims 1 to 4, wherein a fixed position preload is applied to a pair of rolling bearings so as to form a rear combination.   The rolling bearing unit for swing arms according to any one of claims 1 to 5, wherein the inner member is made of any one of austenitic stainless steel, martensitic stainless steel, and aluminum alloy. A rolling bearing unit for a swing arm according to any one of claims 1 to 6, a swing arm fixed to the outer peripheral surface of the outer cylinder, and a base portion to which an inner member is fixed, and having a diameter of 2.5 inches or less. A magnetic disk drive that uses a magnetic disk.

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