JP2012237403A - Fixing structure, and method of bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing structure and fixing method of a bearing, that can surely fix the bearing supporting a shaft even when a large axial force is generated in the bearing, secure the fixation of the bearing by a caulking ring without enhanced processing accuracy, and attain them without enlargement of caulking equipment for attaching the caulking ring.SOLUTION: The fixing structure of a bearing is configured to caulk a cylindrical caulking ring 3 to an annular groove 10 formed in a shaft 1. The groove 10 is formed from a first groove 5 and a second groove 4 defined by an annular protruding part 8 provided at the middle of the groove width in the axial direction so that its upper end is protruded to substantially the same height as the shaft diameter. The caulking ring 3 has a ring inside surface including a first inside surface 3b facing the first groove 5 and a second inside surface 3c facing the second groove 4, and is configured to be engaged with the annular protruding part 8.

Description

  The present invention relates to a bearing fixing technique, and more particularly to a bearing fixing structure and a fixing method for fixing a bearing that supports a pinion shaft of an electric power steering apparatus to the pinion shaft.

  For the purpose of improving fuel efficiency, there are an increasing number of cases in which an electric power steering device is used as a steering device for an automobile, and there is a demand for mounting on a larger automobile. For this reason, each component constituting the electric power steering is required to have higher strength than before.

  In a rack and pinion type steering apparatus that is commonly used, among the bearings that support the pinion shaft, a method for fixing the bearing on the steering wheel side is to form a cylindrical groove in an annular groove formed on the pinion shaft. A method of caulking the caulking ring is adopted.

  Examples of prior art bearing fixing structures include those shown in Patent Document 1 and Patent Document 2, for example. Patent Document 1 discloses a bearing fixing structure in which a clearance between the caulking ring and the pinion shaft, which is likely to occur when the inner ring of the ball bearing is fixed to the pinion shaft by the caulking ring, is not generated. Yes.

  Patent Document 2 discloses a bearing fixing structure that can securely fix a component to the shaft even if there is a manufacturing error of the shaft and the component that fixes the axial position of the shaft.

Japanese Patent Laid-Open No. 2007-9940 JP 2008-57589 A

  The bearing fixing structures of Patent Document 1 and Patent Document 2 are obtained by caulking a cylindrical caulking ring in an annular groove, and by devising the shape of the bearing, the shaft, and the caulking ring, This prevents a gap from being formed between the caulking rings and securely fixes the bearing.

Such a bearing fixing structure has the following problems.
In the structure shown in Patent Document 1, since the inner ring of the bearing is configured to be provided with a groove having a notched cross-sectional shape and fitted with a caulking ring, the bearing structure becomes complicated. As a result, the bearings are designed exclusively and are not versatile, which is a major factor in increasing production costs. In addition, in order to securely tighten the crimping ring without any gap between the shaft groove and the bearing, the load from the crimping jig must be large, resulting in an increase in the size of the crimping equipment. This was a major factor in increasing costs.

  In the structure shown in Patent Document 2, the width of the groove (length in the axial direction) is formed large, and the width of the crimping ring corresponding to this width is also large. The load increases. As a result, there is a need for equipment that enables a large load in the caulking process, and the equipment becomes large.

  In both of the above-mentioned Patent Documents 1 and 2, etc., the both ends of the caulking ring are inserted with a predetermined length between the groove side wall and the end surface of the bearing so that the caulking process can be surely performed. The length in the axial direction and the length in the axial direction of the annular groove required precise machining.

  In the conventional fixing structure of the bearing 200 shown in FIG. 7, the caulking ring 300 is in contact with the rounded portion 600 at the corner of the groove 500. In such a structure, when the axial force F0 is generated in the bearing 200, the direction of the reaction force F1 that the crimping ring 300 receives from the shaft 100 is the normal direction of the contact surface. In the portion in contact with the rounded portion 600, a component force F2 in the axial diameter direction is generated. When the diameter of the caulking ring 300 is expanded by the component force F2, the caulking ring 300 moves in the axial direction so as to slide along the rounded portion 600 at the corner of the groove 500. Low ability to hold in direction.

  The present invention has been made in view of the above circumstances, and its purpose is to ensure that even when a large axial force is generated in the bearing that supports the pinion shaft due to the output of the motor of the electric power steering device or the external force from the road surface. A bearing that can be fixed and that can secure the bearing with a caulking ring without improving the machining accuracy, and can achieve these objectives without enlarging the caulking equipment for mounting the caulking ring. It is to provide a fixing structure and a fixing method.

The above object of the present invention can be achieved by the following constitution.
(1) In a bearing fixing structure for fixing a bearing by caulking a cylindrical caulking ring in an annular groove formed in the shaft,
The groove is formed of a first groove and a second groove defined by an annular ridge formed in the middle of the groove width in the axial direction, and the inner surface of the caulking ring faces the first groove. A bearing fixing structure comprising a ring first inner side surface and a ring second inner side surface facing the second groove and engaging with the annular raised portion.
(2) The bearing fixing structure according to (1), wherein the annular ridge is configured so that an upper end thereof is raised to a height substantially equal to the shaft diameter.
(3) The depth of the second groove located on the side opposite to the bearing relative to the first groove located on the bearing side with respect to the annular ridge is configured to be shallower (1) or The bearing fixing structure according to (2).
(4) The caulking ring is configured such that the inner surface of the ring is held by the annular ridge and does not contact the bottom of the first groove located on the bearing side with respect to the annular ridge. The bearing fixing structure according to any one of (1) to (3), wherein:
(5) In a bearing fixing method of fixing a bearing by caulking a cylindrical caulking ring in an annular groove formed in the shaft,
The groove is partitioned into a first groove and a second groove by an annular ridge formed in the middle of the groove width in the axial direction, and when the crimping ring is crimped, one end surface of the crimping ring is A method for fixing a bearing, wherein a crimping pressure is applied in a state where the ring makes contact with the bearing and the inner surface of the ring faces the annular ridge, and the annular ridge is caused to bite into the inner surface of the ring.

According to the bearing fixing structure of the present invention, when the caulking ring is caulked and installed, the inner surface of the caulking ring and the annular ridge are correspondingly caulked and engaged with the groove. Since the caulking ring is attached so as to bite by the caulking operation of the caulking process itself, the bearing can be fixed with high accuracy regardless of the machining accuracy of the caulking ring mounting site.
Further, according to the bearing fixing structure of the present invention, the second groove can secure a space where the plastic deformation portion of the counter-bearing side end of the caulking ring can be easily deformed, so that the pressure during plastic deformation is effective. It is a structure that can be escaped. As a result, the load during caulking can be kept small, and the processing equipment can be downsized.

According to the bearing fixing method of the present invention, when the caulking ring is caulked and attached, the caulking ring inner surface and the annular bulging portion are caulked in a state of facing each other. The inner surface of the ring is plastically deformed and pushed between the bearing and one side wall of the annular ridge, and this pushed portion is processed to match the actual dimensions of the bearing and one side wall of the annular ridge. As a result, the bearing can be reliably locked without depending on the length dimension of the crimping ring, the groove dimension accuracy, and the like.
Further, according to the bearing fixing method of the present invention, at the time of the plastic deformation, the second groove is deformed while securing a space where the plastic deformation portion of the counter-bearing side end of the caulking ring is easily deformed. The deformation resistance can be reduced, and the load during caulking can be kept small.

It is a principal part expanded sectional view of 1st Embodiment which shows the fixing structure of the bearing of this invention. It is the expanded sectional view which expanded a part of groove | channel shown in FIG. It is explanatory drawing shown in the principal part cross section which shows the state before crimping in which the crimping ring was mounted | worn to the axis | shaft in 1st Embodiment of this invention. It is a principal part expanded sectional view of FIG. It is sectional drawing in the middle of the crimping of the crimping ring in 1st Embodiment of this invention. It is a principal part expanded sectional view of 2nd Embodiment which shows the fixing structure of the bearing of this invention. It is sectional drawing which shows the fixing structure of the bearing of a prior art example.

  Hereinafter, an embodiment of a bearing fixing structure according to the present invention will be described with reference to the drawings.

(First embodiment)
1 shows a bearing fixing structure after caulking in the first embodiment of the present invention, FIG. 2 is a partially enlarged view of FIG. 1, and FIGS. 3 and 4 show a state before caulking, Reference numeral 5 denotes the middle of caulking. In FIG. 3, the bearing and the caulking ring are shown as cross sections.

In the present embodiment, a state in which a ball bearing (hereinafter simply referred to as “bearing”) is assembled to a pinion shaft (hereinafter simply referred to as “shaft”) is shown. That is, as shown in FIG. 1, a cylindrical caulking ring 3 is caulked in an annular groove 10 formed in the shaft 1 (see FIG. 3) to fix the bearing 2 so that it cannot move in the axial direction. This is a bearing fixing structure.
As one feature of the present embodiment, the groove 10 is provided with an annular ridge portion 8 whose upper end 8a rises to substantially the same height as the shaft diameter in the middle of the groove width in the axial direction. Thus, the first groove 5 on the bearing side and the second groove 4 on the opposite bearing side are partitioned.

The first groove 5 formed from the annular ridge 8 to the bearing 2 side is formed with an annular groove round portion 6 at the base of the annular ridge 8 on the side opposite to the bearing 2. The groove depth is increased toward the groove bottom 6 a of the portion 6. Further, the annular raised portion 8 is provided with a side surface 7 rising from the groove rounded portion 6 with a steep slope in the axial outer diameter direction (the direction of the upper end 8a).
As shown in FIG. 2, a portion near the upper end 8 a of the side surface 7 is provided with a crowning portion 7 a configured such that the side surface 7 slightly expands toward the bearing 2. By providing the crowning portion 7a, when the axial force of the bearing 2 is applied to the caulking ring 3, the edge load of the portion of the ring first inner side surface 3b of the caulking ring 3 in contact with the side surface 7 is reduced. Generation | occurrence | production can be reduced and the capability to hold | maintain the bearing 2 to an axial direction can be improved.
The shape of the upper end 8a of the annular ridge 8 is preferably rounded to avoid stress concentration in the ring groove 9.

On the other hand, as shown in FIG. 1, the caulking ring 3 includes a ring first inner surface 3 b whose inner surface faces the first groove 5 and a ring second inner surface 3 c which faces the second groove 4. Has been.
Therefore, the caulking ring 3 is configured such that one end of the ring first inner side surface 3b is in contact with the side surface 7 with respect to the annular ridge portion 8 and the ring second inner side surface 3c is opposite to the bearing side from the upper end 8a of the annular ridge portion 8. The second groove 4 is configured to extend, for example, to about 2/3 of the length of the second groove 4 (left side in FIG. 1). The shape of the ring outer surface 3a is not particularly limited. For example, as shown in FIG. 1, it can be structured such that the ring outer surface 3a is narrowed inwardly toward the counter-bearing side end 3f. Further, when the caulking ring 3 is pushed into the first groove 5, the side surface 7 and the ring outer surface 3 a should be substantially perpendicular to make it difficult for a gap to be generated between the side surface 7 and the caulking ring 3. preferable.

  As described above, in the present embodiment, when the crimping ring 3 is crimped, the ring inner surface (the ring first inner surface 3b and the ring second inner surface 3c) of the crimping ring 3 and the annular ridge 8 And are correspondingly crimped and engaged with the groove 10. This will be described in detail in a later-described caulking method, but the caulking ring 3 is attached so as to bite in accordance with the dimension between the other end surface 35 and the side surface 7 by the caulking operation of the caulking process itself. Therefore, for example, the caulking ring 3 only needs to have the non-bearing side end 3f positioned on the second groove 4 side with the bearing side end 3e in contact with the other end surface 35, and the dimensional accuracy thereof is relatively rough. Good accuracy.

  Further, in the present embodiment, the anti-bearing side end 3f of the caulking ring 3 does not contact the side surface of the groove 10 (the anti-bearing side surface 4a). This is a structure in which the pressure at the time of plastic deformation is effectively released because plastic deformation can be performed without receiving a reaction force from the wall surface that hinders plastic deformation of the anti-bearing side end 3f of the caulking ring 3. . As a result, the load during caulking can be kept small, and the processing equipment can be downsized.

In the present embodiment, the depth of the second groove 4 located on the side opposite to the bearing is smaller than the first groove 5 located on the bearing 2 side with respect to the annular ridge 8.
As described above, since the second groove is formed shallow, the shaving amount of the shaft can be minimized. Furthermore, the rigidity can be increased with respect to the force in the anti-bearing direction of the annular ridge portion 8 (force for moving the bearing 2 in the axial direction). Further, during the caulking process, the inner surface of the caulking ring 3 comes into contact with the second groove 4 earlier than the first groove 5, so that the caulking ring 3 is in the first position as shown in FIG. It is possible to easily avoid contact with the groove bottom 6a of the groove 5.

  As described above, the caulking ring 3 is configured so as not to be in contact with the bottom surface of the first groove 5 so that the caulking ring 3 is not affected when a large axial force is generated in the bearing 2. The radial component of the load (F2 in FIG. 7) can be kept low. As a result, the deformation of the caulking ring 3 is effectively suppressed, and the force for holding the bearing 2 is improved as compared with the prior art.

The caulking method of the caulking ring 3 will be described with reference to FIGS.
First, the groove 10 is provided with an annular raised portion 8 whose upper end 8a rises to the same height as the shaft diameter in the middle of the axial width of the shaft 2.
In the caulking process, as shown in FIG. 3, the shaft 1 is externally fitted in the order of the bearing 2 and the caulking ring 3. At this time, the one end surface 34 of the bearing 2 comes into contact with the first step surface 25 and stops. Further, the bearing side end 3 e of the caulking ring 3 abuts on the other end surface 35 of the bearing 2.

  At this time, the position of the crimping ring 3 with respect to the groove 10 is such that the ring inner surface 3d (ring inner surface before crimping) of the crimping ring 3 faces the annular ridge 8 as shown in FIG. The counter bearing side end 3 f of the caulking ring 3 is positioned in the second groove 4.

In this state, for example, a caulking jig having a substantially conical hole so as to press the caulking ring outer surface 3a and the counter-bearing side end 3f of the caulking ring 3 with a caulking jig (not shown). The caulking ring 3 is caulked in the axial radial direction by axial caulking using a tool, radial caulking, rolling caulking, or the like.
The caulking ring 3 is actually plastically deformed instantly by the action of the caulking force. For example, in the initial stage of caulking, as shown in FIG. 8 begins to deform so that it bites in. Then, a ring groove 9 that matches the shape of the upper end portion of the annular raised portion 8 is formed in the caulking ring 3.

  Thus, in this embodiment, when the crimping ring 3 is crimped and mounted, the ring inner surface 3d of the crimping ring 3 and the annular ridge 8 are crimped so that the annular ridge is formed. The inner surface of the ring is plastically deformed by the portion 8 and is pushed between the bearing 2 and the first groove 5, and processing corresponding to the actual dimensions of the bearing 2 and the first groove 5 is performed. That is, the dimension of the portion having the function of locking the bearing 2 of the caulking ring 3 is determined by caulking, so that it does not depend on the length dimension of the caulking ring 3, the dimensional accuracy of the groove 10, and the like. The bearing 2 can be reliably locked.

Further, when the inner ring side surface 3 d to be crimped is deformed so as to be divided into the first groove 5 and the second groove 4, the counter-bearing side end 3 f of the crimping ring 3 does not contact the side surface 4 a of the groove 10. . That is, since the plastic deformation of the anti-bearing side end 3f of the caulking ring 3 during the caulking process is easy to deform in the axial direction (anti-bearing direction), the conventional plastic deformation due to the groove side surface is hindered. The load during caulking can be kept small without receiving a large resistance during deformation.
Compared with the conventional structure without the second groove 4, that is, the caulking force when the entire caulking ring 300 is pushed into the groove 500 as in the prior art as shown in FIG. Can be concentrated in the vicinity of the annular ridge 8 and the load at the time of caulking can be kept small by the relatively sharp shape of the annular ridge 8.
Moreover, when the shape of the ring outer surface 3a is substantially perpendicular to the side surface 7, the crimping ring 3 can be crimped efficiently in the axial radial direction. The ring outer surface 3a may be substantially conical or slightly curved.
Further, the shape of the upper end 8a of the annular ridge 8 is preferably rounded to avoid stress concentration in the ring groove 9.

(Second Embodiment)
FIG. 6 shows a cross-sectional view of relevant parts in the second embodiment of the present invention.
FIG. 6 is a sectional view showing a bearing fixing structure after caulking in a second embodiment of the present invention.
In FIG. 6, the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.
The caulking structure in the present embodiment is basically the same structure as in the first embodiment, but compared to the first embodiment, the annular ridge 8 moves to the bearing 2 side and the width of the second groove 4 is increased. Is formed large. The depth of the second groove 4 is also slightly deeper than that of the first embodiment. Also, the shape of the ring outer surface 3a is a structure that is not squeezed inward in the ring diameter toward the non-bearing side end 3f. Therefore, the volume of the portion of the caulking ring 3 that has entered the second groove 4 is increased. A taper surface 30e is provided at the bearing side end 3e of the caulking ring 3, and a taper surface 30f is provided at the counter bearing side end 3f.

  Since the annular ridge portion 8 has moved to the bearing 2 side in this way, the volume of the portion on the side opposite to the bearing side end 3f in the caulking ring 3 from the annular ridge portion 8 can be increased. The strength of the portion on the bearing side end 3f side can be improved.

The first and second embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like can be made as appropriate. That is, the shape of the annular raised portion, the shape of the caulking ring, and the like can be changed as appropriate.
In the above embodiment, the case where the bearing inner ring is fixed to the shaft has been described. However, the same fixing structure can be used when the bearing outer ring is fixed to the housing.

1 shaft 2 bearing 3 caulking ring 3a ring outer surface 3b ring first inner side surface 3c ring second inner side surface 4 second groove 5 first groove 6 groove rounded part 6a groove bottom 7 side 7a crowning part 8 annular raised part 8a upper end 9 Ring groove 10 Groove

Claims (5)

In the bearing fixing structure in which a cylindrical caulking ring is caulked in an annular groove formed in the shaft to fix the bearing,
The groove is formed of a first groove and a second groove defined by an annular ridge formed in the middle of the groove width in the axial direction, and the inner surface of the caulking ring faces the first groove. A bearing fixing structure comprising a ring first inner side surface and a ring second inner side surface facing the second groove and engaging with the annular raised portion.   2. The bearing fixing structure according to claim 1, wherein an upper end of the annular raised portion is configured to rise to substantially the same height as the shaft diameter. 3.   The depth of the said 2nd groove | channel located in an anti-bearing side is shallower than the said 1st groove | channel located in the said bearing side with respect to the said cyclic | annular protruding part, The structure characterized by the above-mentioned. Bearing fixing structure.   The caulking ring is configured such that an inner surface of the ring is held by the annular ridge, and does not contact a groove bottom of the first groove located on the bearing side with respect to the annular ridge. The bearing fixing structure according to any one of claims 1 to 3. In a method for fixing a bearing, in which a cylindrical caulking ring is caulked in an annular groove formed in the shaft to fix the bearing,
The groove is partitioned into a first groove and a second groove by an annular ridge formed in the middle of the groove width in the axial direction, and when the crimping ring is crimped, one end surface of the crimping ring is A method for fixing a bearing, wherein a crimping pressure is applied in a state where the ring makes contact with the bearing and the inner surface of the ring faces the annular ridge, and the annular ridge is caused to bite into the inner surface of the ring.

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