CA2048531A1 - Bearing and method of manufacturing same - Google Patents
Bearing and method of manufacturing sameInfo
- Publication number
- CA2048531A1 CA2048531A1 CA002048531A CA2048531A CA2048531A1 CA 2048531 A1 CA2048531 A1 CA 2048531A1 CA 002048531 A CA002048531 A CA 002048531A CA 2048531 A CA2048531 A CA 2048531A CA 2048531 A1 CA2048531 A1 CA 2048531A1
- Authority
- CA
- Canada
- Prior art keywords
- bearing
- shaft
- axial direction
- base portion
- mounting base
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R22/00—Safety belts or body harnesses in vehicles
- B60R22/34—Belt retractors, e.g. reels
- B60R22/36—Belt retractors, e.g. reels self-locking in an emergency
- B60R22/42—Belt retractors, e.g. reels self-locking in an emergency having means for acting directly upon the belt, e.g. by clamping or friction
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C11/00—Pivots; Pivotal connections
- F16C11/04—Pivotal connections
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C17/00—Sliding-contact bearings for exclusively rotary movement
- F16C17/02—Sliding-contact bearings for exclusively rotary movement for radial load only
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/02—Parts of sliding-contact bearings
- F16C33/04—Brasses; Bushes; Linings
- F16C33/06—Sliding surface mainly made of metal
- F16C33/14—Special methods of manufacture; Running-in
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C2220/00—Shaping
- F16C2220/40—Shaping by deformation without removing material
- F16C2220/46—Shaping by deformation without removing material by forging
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C2220/00—Shaping
- F16C2220/60—Shaping by removing material, e.g. machining
- F16C2220/66—Shaping by removing material, e.g. machining by milling
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Mounting Of Bearings Or Others (AREA)
- Automotive Seat Belt Assembly (AREA)
- Motor Or Generator Frames (AREA)
- Sliding-Contact Bearings (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A bearing is formed into a ring-shaped configuration in which a mounting base portion and a bearing portion which supports a shaft define an L-shaped cross section. The center of the bearing portion in the axial direction of the shaft is set at a position which is superimposed on the base portion in the axial direction, or in close proximity to the position of the base portion in the axial direction. The bearing is manufactured first by subjecting a flat plate to burring work to form a ring-shaped bearing blank in which the mounting base portion and the bearing portion define an L-shaped configuration, and then subsequently compression-molding the bearing portion of the bearing blank into prescribed dimensions in the axial direction.
A bearing is formed into a ring-shaped configuration in which a mounting base portion and a bearing portion which supports a shaft define an L-shaped cross section. The center of the bearing portion in the axial direction of the shaft is set at a position which is superimposed on the base portion in the axial direction, or in close proximity to the position of the base portion in the axial direction. The bearing is manufactured first by subjecting a flat plate to burring work to form a ring-shaped bearing blank in which the mounting base portion and the bearing portion define an L-shaped configuration, and then subsequently compression-molding the bearing portion of the bearing blank into prescribed dimensions in the axial direction.
Description
SPECIFICATION
TITLE OF THE INVENTION
BEARING AND METHOD OF MANUFACTURING SAME
BAC~GRO~ND OF THE INVENTION
This invention relates to a bearing of a shaft which supports a lever or the like, and to a method of manufacturing the bearing. More particularly, the invention relates to a ring-shaped bearing in which a mounting base portion and a bearing portion for supporting a shaft are formed into an L-shaped configuration, and to a method of manufacturing such a bearing.
The seat belt apparatus of an automotive vehicle generally is provided with a retractor for taking up a webbing. The retractor is so adapted that a reel shaft which takes up the webbing is freed for rotation under ordinary conditions, thereby making it possible for the webbing to be pulled freely from the reel shaft so that the webbing will not restrain the passenger wearing it.
At the occurrence of an emergency such as a collision, however, the reel shaft is locked against rotation by locking means so that the webbing is incapable of being pulled from the reel shaft. This allows the webbing to restrain and protect the passenger.
Though the means for locking the reel shaft which takes up the webbing is capable of reliably halting the rotation of the reel shaft per se, there are occasions when excess webbing that has been taken up on the reel 2~
shaft is pulled off as a result of tightening even through the reel shaft has been stopped from rotating.
In order to prevent such pulling off of the webbing due to tightening, a seat belt retractor of the kind shown in Fig. 4 has been proposed.
As illustrated in Fig. 4, a seat belt retractor 1 comprises a pendulum attached to a frame 2 for being tilted when subjected to an impact force in excess of a predetermined value, a ratchet 5 coaxially fixed to a reel shaft (not shown) which takes up a webbing 4, a link 6 actuated by tilting of the pendulum 3 so that a pawl 6a thereof engages with a tooth of the ratchet 5 and is moved upward by a turning force produced by the ratchet 5, and a stopper member 8 turnably mounted on the frame 2 for being turned by upward movement of the link 6 so as to clamp the webbing 4 between itself and a wall member 7.
With the seat belt retractor 1 of this type, the stopper member 8 clamps the webbing 4 per se between itself and the wall member 7 at the occurrence of an emergency, as a result of which the webbing 4 can be prevented from being pulled out due to sudden tightening.
In the conventional seat belt retractor 1 which prevents pull-out of the webbing 4 due to sudden tightening of the webbing, the stopper member 8 is turnably supported on the frame 2 by a shaft 9. In this case, the shaft 9 has both its ends supported on the - 3 - 2~2~
frame 2 by a palr of bearings 10, as shown in Fig. 5.
As shown in greater detail in Fig. 6, each bearing 10, which ordinarily is formed by burring work, has a ring-shaped configuration formed to have a bearing portion lOa and a mounting base portion lOb which, in combination, are bent to have an L-shaped cross section.
In the bending work performed by burring, the bending radius is comparatively large. As a result, the bearing 10 is such that a center point c, along the axial direction, of a bearing surface a of the bearing portion lOa is remote from the mounting base portion lOb in terms of the axial direction.
Accordingly, in the case where both ends of the shaft 9 are supported by the pair of bearings 10, as shown in Fig. 5, the centers cl, c2 of the bearing surfaces a of the two bearings 10 become far apart.
Furthermore, in order to minimize the stress produced when a load is received from the shaft 9, the surface area of the bearing portion lOa which supports the shaft 9 is enlarged. As a result, there is large a distance a1 between the centers of loads f which act upon the bearing surfaces a of the bearing portions lOa due to the load from the shaft 9, namely the distance between the centers c1, c2 of the bearing portions lOa.
When there is such a large distance al between the centers c1, c2 of the loads f in the two bearings 10, this inevitably leads to a large moment M which is produced by the shaft 9. As a result, the bending ~8~
stress developed by the shaft 9 also is enlarged. This means that the shaft 9 must be provided with enough strength to resist this bending stress. In order to assure the strength of the shaft 9, however, its diameter must be increased. In particular, when the stopper member 8 clamps the webbing 4 per se between itself and the wall member 7 in the retractor 1, a large load F is applied to the shaft 9. Thls makes it necessary to provide the shaft 9 with an especially large diameter. As a consequence, the shaft 9 not only requires use of a large amount of material owing to its larger size, but the weight and cost of the shaft a'so increase correspondingly.
Furthermore, reducing the size and weight of the bearing 10 to the maximum extent possible is desirable in terms of reducing the overall weight of the vehicle.
To this end, it has been contemplated to make the plate ~-thickness of the bearing 10 as small as possible.
However, when the plate thickness of the bearing 10 is made small, the bearing surface a becomes too distant from the mounting base portion lOb in the case of the bearing 10 formed by burring, as described above. Owing to this great distance, the buckling strength at the bent portion A shown in Fig. 6 becomes too small. As a ~5 consequence, when a load acts upon the shaft 9 in the z direction, the bent portion A is deformed and, hence, the bearing portion lOa and shaft 9 move in the z direction, thus reducing the clamping force.
- s-SVMMARY OF THE INVENTION
An object of the present invention is to provide a bearing, and a method of manufacturing the same, in which stress produced by a load acting upon a shaft can be minimized, as a result of which the shaft can be greatly reduced in size and formed at low cost.
Another object of the present invention is to provide a bearing, and a method of manufacturing the same, in which weight can be reduced and sufficient strength assured.
According to the present invention, the foregoing objects are attained by providing a ring-shaped bearing in which a mounting base portion and a bearing portion which supports a shaft are formed into an L-shaped configuration, characterized in that a center of the bearing portion in an axial direction is set at a position which is superimposed on the base portion in the axial direction, or in close proximity to the position of the base portion in the axial direction.
Further, according to the present invention, there is provided a method of manufacturing a bearing characterized by a step of forming, by burring, a flat plate into a ring-shaped bearing blank in which a mounting base portion and a bearing portion which supports a shaft are formed into an L-shaped configuration, and a pressing step of subsequently compression-molding the bearing portion of the bearing blank into prescribed dimensions in an axial direction.
In the bearing of the present invention constructed as set forth above, the center of the bearing surface of the bearing in the axial direction is set at a position superimposed on the mounting base portion in the axial direction, or at a position which is very close to the mounting base portion in the axial direction.
Accordingly, when the shaft is supported by the bearing portions of a pair of the bearings, the distance between the centers of the bearing surfaces of these bearing portions is reduced in comparison with the conventional bearing. Consequently, the bending moment produced by the load which acts upon the shaft is reduced and so is the bending stress developed by the shaft. As a result, the diameter of the shaft can be greatly reduced. Furthermore, even in a case where the shaft is supported by the bearing of this invention and another bearing, such as the conventional bearing, the distance between the centers of the bearing portions of these bearings is reduced.
Since the center of the bearing surface in the axial direction is superimposed on the mounting base portion in the axial direction or is situated in close proximity to the mounting base portion in the axial direction, there is a substantial increase in the strength of the bent portion between the bearing portion and the mounting base portion. Accordingly, even if the plate thickness of the bearing is made small, the bent portion will not undergo buckling deformation and, as a result, the bearing portion and the shaft will not move in the direction perpendicular to the axial direction.
In the method of manufacturing the bearing according to the present invention, the bearing is molded by press machining. Therefore, merely assuring the dimen~ional precision of the press mold ma~es it possible to improve the accuracy of the bearing hole and also to mass-produce a high-precision bearing in a simple manner.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification. The invention accordingly comprises the features of construction, combinations of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a sectional view illustrating an embodiment of a bearing according to the present nventlon;
Fig. 2 is a sectional view schematically illustrating the state in which a shaft is supported by the bearing of this embodiment;
Fig. 3 is for describing a method of manufacturing a bearing according to the embodiment of the invention, in which (a) is a diagram illustrating the step for manufacturing a bearing blank and (b) is a diagram illustrating a bearing pressing step;
Fig. 4 is a perspective view showing a seat belt retractor according to the prior art;
Fig. 5 is a sectional view schematically illustrating the state in which a shaft is supported by a bearing according to the prior art; and Fig. 6 is a sectional view showing the bearing according to the prior art.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Fig. 1 is a sectional view, similar to that of Fig.
6, showing an embodiment of the present invention, and Fig. 2 is a partial sectional view, similar to that of Fig. 5, showing the state in which a shaft is supported using the bearing according to this embodiment.
Further, components identical with those of the prior art shown in Figs. 4 through 6 are designated by line reference characters and need not be described again.
An apostrophe (') is attached to reference numerals of portions which correspond to those of Figs. 4 through 6 but which are different.
As illustrated in Fig. 1, a bearing 10' according to this embodiment includes a bearing portion 10a' having a bearing surface a whose center c is set at a position superimposed on a mounting base portion 10b' in the axial direction. Accordingly, the bearing 10' has a high strength against bending at a bent portion A
between the bearing portion 10a' and the mounting base portion 10b'.
It should be noted that the center c of the bearing surface a need not necessarily be at a position which is superimposed on the mounting base portion lOb in the axial direction. Depending upon the plate thickness, it will sufflce if the center c of the bearing surface a is situated at a position very close to the base portion lOb' in comparison with the prior art.
Accordingly, in a case where the shaft 9 is supported by the bearings 10' of the embodiment, as shown in Fig. 2, the centers c1, c2 of the bearing surfaces a in the axial direction of the two bearings 10' at both ends of the shaft 9 are much closer together in comparison with the prior-art bearing 10. As a result, the distance between the centers of the two bearing surfaces a, namely a distance a2 between the centers c1, c2 of loads f acting upon the bearing 10', is less than the distance a1 between the centers c1, c2 of loads f acting upon the bearing 10 of the prior art (i.e., a2 < a1).
With regard to support of the shaft 9 by the bearings 10' of this embodiment in which the distance a2 between the centers c1, c2 of loads f is thus reduced, the bending moment M produced by the shaft 9 also is reduced by (a2/a1)2 over the prior art. As a result, the bending stress developed by the shaft 9 also is made small.
Since the strength of the bearing 10' against bending is enlarged, the bent portion A of the bearing 10' does not undergo deformation when the load f is received from the shaft 9, even if the plate thickness of the bearing 10' is made small. Accordingly, the bearing lOa' and the shaft 9 will not move in the z direction, and therefore a sufficient clamping force can be assured for the stopper member 8 relative to the webbing 4.
A method of forming the bearing 10~ according to this embodiment will now be described.
As shown in Fig. 3(a), first a bearing blank 10"
exhibiting a comparatively large bending radius and having a bearing portion lOa" and a mounting base portion lOb" defining an L-shaped configuration is formed by burring work just as in the method of manufacturing the bearing according to the prior art.
Next, as shown in Fig. 3(b), the bearing blank 10" is set in a lower mold 11 in a state where a hole lOc" of a bearing portion lOa" of the bearing blank 10" is mated with a cylindrical projection lla protruding from the lower mold 11. Then, after an upper mold 12 is set upon the upper end oE the bearing portion 10", the bearing lOa" is urged from above by a press via the upper mold 12, whereby the bearing portion lOa' is compressed to a predetermined length. Thus is formed the bearing 10' of this embodiment.
In accordance with this method of manufacture, the inner diameter of the hole lOc in the bearing portion lOa' can be formed to a high precision merely by - 11 - 2~l3~ 3~
assuring that the dimensions of the mold 11 have a prescribed accuracy. Accordingly, not only is the positional accuracy of the shaft 9 improved, but also the possibility that the shaft 9 and the bearing portion lOa' of the bearing 10' will be offset is almost eliminated. In addition, the durability of the shaft 9 and bearing 10' is improved. Furthermore, according to the manufacturing method of the invention, the bearing 10' of high precision can be mass-produced in a simple manner.
Though an embodiment has been described in which the present invention is applied to the bearing of a retractor in a seat belt apparatus, it goes without saying that the invention is applicable also to the 15 bearings of other shafts.
In addition, in the embodiment described above, the two bearings supporting the shaft 9 both employ the bearing according to this invention. However, it goes without saying that the same effects can be obtained even if one bearing is the bearing of the present invention and the other bearing is a different bearing.
In accordance with the bearing of the present invention, as will be evident from the foregoing description, the bearing surface of the bearing is moved 25 closer to the mounting base portion in comparison with the prior-art bearing, and therefore strength against bending is greater in comparison with the prior-art bearing. Accordingly, the plate thickness of the bearing can be made much smaller and it is possible to make the bearing light in weight. In addition, the bearing portion of the bearing will not be deformed by a load from the shaft when the shaft is supported, thus making it possible to prevent the shaft from moving in the direction perpendicular to the axial direction.
In a case where a shaft is supported by a pair of the bearings according to the invention, the distance between the centers of the loads which act upon the bearing is made smaller than that in the prior-art bearing, and therefore the bending moment and bending stress developed by the shaft are reduced in comparison with those of the prior art. Accordingly, the diameter of the shaft can be made much smaller. This makes it possible to economize on the material constituting the shaft, and to reduce cost. Moreover, since the diameter of the shaft can be reduced, it is possible to realize a further reduction in an apparatus formed using the bearing of the invention.
Furthermore, in a case where the bearing is applied to the retractor of a seat belt apparatus, the bending moment which acts upon the shaft is small and therefore the retractor can be provided with a much larger force for clamping the webbing.
In accordance with the method of manufacturing the bearing according to the present invention, the inner diameter of the hole in the bearing portion can be formed to a high precision merely by assuring that the ^ 13 ~
dimensions of the press mold have a prescribed accuracy.
Accordingly, not only is the positional accuracy of the shaft improved, but also the possibility that the shaft and the bearing portion of the bearing will be offset is almost eliminated. In addition, the durability of the shaft and bearing is improved. Furthermore, according to the manufacturing method of the invention, a bearing of high precision can be mass-produced in a simple manner.
0 As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended i5 claims.
TITLE OF THE INVENTION
BEARING AND METHOD OF MANUFACTURING SAME
BAC~GRO~ND OF THE INVENTION
This invention relates to a bearing of a shaft which supports a lever or the like, and to a method of manufacturing the bearing. More particularly, the invention relates to a ring-shaped bearing in which a mounting base portion and a bearing portion for supporting a shaft are formed into an L-shaped configuration, and to a method of manufacturing such a bearing.
The seat belt apparatus of an automotive vehicle generally is provided with a retractor for taking up a webbing. The retractor is so adapted that a reel shaft which takes up the webbing is freed for rotation under ordinary conditions, thereby making it possible for the webbing to be pulled freely from the reel shaft so that the webbing will not restrain the passenger wearing it.
At the occurrence of an emergency such as a collision, however, the reel shaft is locked against rotation by locking means so that the webbing is incapable of being pulled from the reel shaft. This allows the webbing to restrain and protect the passenger.
Though the means for locking the reel shaft which takes up the webbing is capable of reliably halting the rotation of the reel shaft per se, there are occasions when excess webbing that has been taken up on the reel 2~
shaft is pulled off as a result of tightening even through the reel shaft has been stopped from rotating.
In order to prevent such pulling off of the webbing due to tightening, a seat belt retractor of the kind shown in Fig. 4 has been proposed.
As illustrated in Fig. 4, a seat belt retractor 1 comprises a pendulum attached to a frame 2 for being tilted when subjected to an impact force in excess of a predetermined value, a ratchet 5 coaxially fixed to a reel shaft (not shown) which takes up a webbing 4, a link 6 actuated by tilting of the pendulum 3 so that a pawl 6a thereof engages with a tooth of the ratchet 5 and is moved upward by a turning force produced by the ratchet 5, and a stopper member 8 turnably mounted on the frame 2 for being turned by upward movement of the link 6 so as to clamp the webbing 4 between itself and a wall member 7.
With the seat belt retractor 1 of this type, the stopper member 8 clamps the webbing 4 per se between itself and the wall member 7 at the occurrence of an emergency, as a result of which the webbing 4 can be prevented from being pulled out due to sudden tightening.
In the conventional seat belt retractor 1 which prevents pull-out of the webbing 4 due to sudden tightening of the webbing, the stopper member 8 is turnably supported on the frame 2 by a shaft 9. In this case, the shaft 9 has both its ends supported on the - 3 - 2~2~
frame 2 by a palr of bearings 10, as shown in Fig. 5.
As shown in greater detail in Fig. 6, each bearing 10, which ordinarily is formed by burring work, has a ring-shaped configuration formed to have a bearing portion lOa and a mounting base portion lOb which, in combination, are bent to have an L-shaped cross section.
In the bending work performed by burring, the bending radius is comparatively large. As a result, the bearing 10 is such that a center point c, along the axial direction, of a bearing surface a of the bearing portion lOa is remote from the mounting base portion lOb in terms of the axial direction.
Accordingly, in the case where both ends of the shaft 9 are supported by the pair of bearings 10, as shown in Fig. 5, the centers cl, c2 of the bearing surfaces a of the two bearings 10 become far apart.
Furthermore, in order to minimize the stress produced when a load is received from the shaft 9, the surface area of the bearing portion lOa which supports the shaft 9 is enlarged. As a result, there is large a distance a1 between the centers of loads f which act upon the bearing surfaces a of the bearing portions lOa due to the load from the shaft 9, namely the distance between the centers c1, c2 of the bearing portions lOa.
When there is such a large distance al between the centers c1, c2 of the loads f in the two bearings 10, this inevitably leads to a large moment M which is produced by the shaft 9. As a result, the bending ~8~
stress developed by the shaft 9 also is enlarged. This means that the shaft 9 must be provided with enough strength to resist this bending stress. In order to assure the strength of the shaft 9, however, its diameter must be increased. In particular, when the stopper member 8 clamps the webbing 4 per se between itself and the wall member 7 in the retractor 1, a large load F is applied to the shaft 9. Thls makes it necessary to provide the shaft 9 with an especially large diameter. As a consequence, the shaft 9 not only requires use of a large amount of material owing to its larger size, but the weight and cost of the shaft a'so increase correspondingly.
Furthermore, reducing the size and weight of the bearing 10 to the maximum extent possible is desirable in terms of reducing the overall weight of the vehicle.
To this end, it has been contemplated to make the plate ~-thickness of the bearing 10 as small as possible.
However, when the plate thickness of the bearing 10 is made small, the bearing surface a becomes too distant from the mounting base portion lOb in the case of the bearing 10 formed by burring, as described above. Owing to this great distance, the buckling strength at the bent portion A shown in Fig. 6 becomes too small. As a ~5 consequence, when a load acts upon the shaft 9 in the z direction, the bent portion A is deformed and, hence, the bearing portion lOa and shaft 9 move in the z direction, thus reducing the clamping force.
- s-SVMMARY OF THE INVENTION
An object of the present invention is to provide a bearing, and a method of manufacturing the same, in which stress produced by a load acting upon a shaft can be minimized, as a result of which the shaft can be greatly reduced in size and formed at low cost.
Another object of the present invention is to provide a bearing, and a method of manufacturing the same, in which weight can be reduced and sufficient strength assured.
According to the present invention, the foregoing objects are attained by providing a ring-shaped bearing in which a mounting base portion and a bearing portion which supports a shaft are formed into an L-shaped configuration, characterized in that a center of the bearing portion in an axial direction is set at a position which is superimposed on the base portion in the axial direction, or in close proximity to the position of the base portion in the axial direction.
Further, according to the present invention, there is provided a method of manufacturing a bearing characterized by a step of forming, by burring, a flat plate into a ring-shaped bearing blank in which a mounting base portion and a bearing portion which supports a shaft are formed into an L-shaped configuration, and a pressing step of subsequently compression-molding the bearing portion of the bearing blank into prescribed dimensions in an axial direction.
In the bearing of the present invention constructed as set forth above, the center of the bearing surface of the bearing in the axial direction is set at a position superimposed on the mounting base portion in the axial direction, or at a position which is very close to the mounting base portion in the axial direction.
Accordingly, when the shaft is supported by the bearing portions of a pair of the bearings, the distance between the centers of the bearing surfaces of these bearing portions is reduced in comparison with the conventional bearing. Consequently, the bending moment produced by the load which acts upon the shaft is reduced and so is the bending stress developed by the shaft. As a result, the diameter of the shaft can be greatly reduced. Furthermore, even in a case where the shaft is supported by the bearing of this invention and another bearing, such as the conventional bearing, the distance between the centers of the bearing portions of these bearings is reduced.
Since the center of the bearing surface in the axial direction is superimposed on the mounting base portion in the axial direction or is situated in close proximity to the mounting base portion in the axial direction, there is a substantial increase in the strength of the bent portion between the bearing portion and the mounting base portion. Accordingly, even if the plate thickness of the bearing is made small, the bent portion will not undergo buckling deformation and, as a result, the bearing portion and the shaft will not move in the direction perpendicular to the axial direction.
In the method of manufacturing the bearing according to the present invention, the bearing is molded by press machining. Therefore, merely assuring the dimen~ional precision of the press mold ma~es it possible to improve the accuracy of the bearing hole and also to mass-produce a high-precision bearing in a simple manner.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification. The invention accordingly comprises the features of construction, combinations of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a sectional view illustrating an embodiment of a bearing according to the present nventlon;
Fig. 2 is a sectional view schematically illustrating the state in which a shaft is supported by the bearing of this embodiment;
Fig. 3 is for describing a method of manufacturing a bearing according to the embodiment of the invention, in which (a) is a diagram illustrating the step for manufacturing a bearing blank and (b) is a diagram illustrating a bearing pressing step;
Fig. 4 is a perspective view showing a seat belt retractor according to the prior art;
Fig. 5 is a sectional view schematically illustrating the state in which a shaft is supported by a bearing according to the prior art; and Fig. 6 is a sectional view showing the bearing according to the prior art.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Fig. 1 is a sectional view, similar to that of Fig.
6, showing an embodiment of the present invention, and Fig. 2 is a partial sectional view, similar to that of Fig. 5, showing the state in which a shaft is supported using the bearing according to this embodiment.
Further, components identical with those of the prior art shown in Figs. 4 through 6 are designated by line reference characters and need not be described again.
An apostrophe (') is attached to reference numerals of portions which correspond to those of Figs. 4 through 6 but which are different.
As illustrated in Fig. 1, a bearing 10' according to this embodiment includes a bearing portion 10a' having a bearing surface a whose center c is set at a position superimposed on a mounting base portion 10b' in the axial direction. Accordingly, the bearing 10' has a high strength against bending at a bent portion A
between the bearing portion 10a' and the mounting base portion 10b'.
It should be noted that the center c of the bearing surface a need not necessarily be at a position which is superimposed on the mounting base portion lOb in the axial direction. Depending upon the plate thickness, it will sufflce if the center c of the bearing surface a is situated at a position very close to the base portion lOb' in comparison with the prior art.
Accordingly, in a case where the shaft 9 is supported by the bearings 10' of the embodiment, as shown in Fig. 2, the centers c1, c2 of the bearing surfaces a in the axial direction of the two bearings 10' at both ends of the shaft 9 are much closer together in comparison with the prior-art bearing 10. As a result, the distance between the centers of the two bearing surfaces a, namely a distance a2 between the centers c1, c2 of loads f acting upon the bearing 10', is less than the distance a1 between the centers c1, c2 of loads f acting upon the bearing 10 of the prior art (i.e., a2 < a1).
With regard to support of the shaft 9 by the bearings 10' of this embodiment in which the distance a2 between the centers c1, c2 of loads f is thus reduced, the bending moment M produced by the shaft 9 also is reduced by (a2/a1)2 over the prior art. As a result, the bending stress developed by the shaft 9 also is made small.
Since the strength of the bearing 10' against bending is enlarged, the bent portion A of the bearing 10' does not undergo deformation when the load f is received from the shaft 9, even if the plate thickness of the bearing 10' is made small. Accordingly, the bearing lOa' and the shaft 9 will not move in the z direction, and therefore a sufficient clamping force can be assured for the stopper member 8 relative to the webbing 4.
A method of forming the bearing 10~ according to this embodiment will now be described.
As shown in Fig. 3(a), first a bearing blank 10"
exhibiting a comparatively large bending radius and having a bearing portion lOa" and a mounting base portion lOb" defining an L-shaped configuration is formed by burring work just as in the method of manufacturing the bearing according to the prior art.
Next, as shown in Fig. 3(b), the bearing blank 10" is set in a lower mold 11 in a state where a hole lOc" of a bearing portion lOa" of the bearing blank 10" is mated with a cylindrical projection lla protruding from the lower mold 11. Then, after an upper mold 12 is set upon the upper end oE the bearing portion 10", the bearing lOa" is urged from above by a press via the upper mold 12, whereby the bearing portion lOa' is compressed to a predetermined length. Thus is formed the bearing 10' of this embodiment.
In accordance with this method of manufacture, the inner diameter of the hole lOc in the bearing portion lOa' can be formed to a high precision merely by - 11 - 2~l3~ 3~
assuring that the dimensions of the mold 11 have a prescribed accuracy. Accordingly, not only is the positional accuracy of the shaft 9 improved, but also the possibility that the shaft 9 and the bearing portion lOa' of the bearing 10' will be offset is almost eliminated. In addition, the durability of the shaft 9 and bearing 10' is improved. Furthermore, according to the manufacturing method of the invention, the bearing 10' of high precision can be mass-produced in a simple manner.
Though an embodiment has been described in which the present invention is applied to the bearing of a retractor in a seat belt apparatus, it goes without saying that the invention is applicable also to the 15 bearings of other shafts.
In addition, in the embodiment described above, the two bearings supporting the shaft 9 both employ the bearing according to this invention. However, it goes without saying that the same effects can be obtained even if one bearing is the bearing of the present invention and the other bearing is a different bearing.
In accordance with the bearing of the present invention, as will be evident from the foregoing description, the bearing surface of the bearing is moved 25 closer to the mounting base portion in comparison with the prior-art bearing, and therefore strength against bending is greater in comparison with the prior-art bearing. Accordingly, the plate thickness of the bearing can be made much smaller and it is possible to make the bearing light in weight. In addition, the bearing portion of the bearing will not be deformed by a load from the shaft when the shaft is supported, thus making it possible to prevent the shaft from moving in the direction perpendicular to the axial direction.
In a case where a shaft is supported by a pair of the bearings according to the invention, the distance between the centers of the loads which act upon the bearing is made smaller than that in the prior-art bearing, and therefore the bending moment and bending stress developed by the shaft are reduced in comparison with those of the prior art. Accordingly, the diameter of the shaft can be made much smaller. This makes it possible to economize on the material constituting the shaft, and to reduce cost. Moreover, since the diameter of the shaft can be reduced, it is possible to realize a further reduction in an apparatus formed using the bearing of the invention.
Furthermore, in a case where the bearing is applied to the retractor of a seat belt apparatus, the bending moment which acts upon the shaft is small and therefore the retractor can be provided with a much larger force for clamping the webbing.
In accordance with the method of manufacturing the bearing according to the present invention, the inner diameter of the hole in the bearing portion can be formed to a high precision merely by assuring that the ^ 13 ~
dimensions of the press mold have a prescribed accuracy.
Accordingly, not only is the positional accuracy of the shaft improved, but also the possibility that the shaft and the bearing portion of the bearing will be offset is almost eliminated. In addition, the durability of the shaft and bearing is improved. Furthermore, according to the manufacturing method of the invention, a bearing of high precision can be mass-produced in a simple manner.
0 As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended i5 claims.
Claims (2)
1. A ring-shaped bearing in which a mounting base portion and a bearing portion which supports a shaft are formed into an L-shaped configuration, characterized in that a center of said bearing portion in an axial direction is set at a position which is superimposed on said base portion in the axial direction, or in close proximity to the position of said base portion in the axial direction.
2. A method of manufacturing a bearing comprising the steps of:
forming, by burring, a flat plate into a ring-shaped bearing blank in which a mounting base portion and a bearing portion which supports a shaft are formed into an L-shaped configuration; and a step of subsequently compression-molding the bearing portion of said bearing blank into prescribed dimensions in an axial direction.
forming, by burring, a flat plate into a ring-shaped bearing blank in which a mounting base portion and a bearing portion which supports a shaft are formed into an L-shaped configuration; and a step of subsequently compression-molding the bearing portion of said bearing blank into prescribed dimensions in an axial direction.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2208643A JPH0491835A (en) | 1990-08-07 | 1990-08-07 | Bearing and production thereof |
| JP208643/1990 | 1990-08-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2048531A1 true CA2048531A1 (en) | 1992-02-08 |
Family
ID=16559643
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002048531A Abandoned CA2048531A1 (en) | 1990-08-07 | 1991-08-07 | Bearing and method of manufacturing same |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPH0491835A (en) |
| KR (1) | KR920004216A (en) |
| CA (1) | CA2048531A1 (en) |
| DE (1) | DE4126190A1 (en) |
| FR (1) | FR2665934B1 (en) |
| GB (1) | GB2247288B (en) |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1867412A (en) * | 1928-12-28 | 1932-07-12 | Cleveland Graphite Bronze Co | Method of making bearings |
| GB552013A (en) * | 1941-07-14 | 1943-03-19 | Phillips & Powis Aircraft Ltd | Improvements in bearings for shafts and rods |
| DE845490C (en) * | 1943-06-07 | 1952-07-31 | Gen Motors Corp | Method of manufacturing bearings |
| GB1104603A (en) * | 1965-10-20 | 1968-02-28 | Takaichi Mabuchi | Bearing of a miniature electric motor |
| DE1957703A1 (en) * | 1969-11-17 | 1971-05-27 | Schmidt Gmbh Karl | Method and device for the production of bundles |
| US4173375A (en) * | 1978-04-14 | 1979-11-06 | Westinghouse Electric Corp. | Remote lubrication system for vertical motor shafts |
| US4578848A (en) * | 1982-09-09 | 1986-04-01 | Aeplc | Method for the manufacture of flanged bearings |
| JPS59199133A (en) * | 1983-04-28 | 1984-11-12 | Oiles Ind Co Ltd | Production of flanged coil bush bearing and die used for production thereof |
| JPS6329362U (en) * | 1986-08-05 | 1988-02-26 | ||
| JPH0443622Y2 (en) * | 1988-03-04 | 1992-10-15 |
-
1990
- 1990-08-07 JP JP2208643A patent/JPH0491835A/en active Pending
-
1991
- 1991-08-01 KR KR1019910013349A patent/KR920004216A/en not_active Application Discontinuation
- 1991-08-06 FR FR9110016A patent/FR2665934B1/en not_active Expired - Fee Related
- 1991-08-07 GB GB9116980A patent/GB2247288B/en not_active Expired - Fee Related
- 1991-08-07 CA CA002048531A patent/CA2048531A1/en not_active Abandoned
- 1991-08-07 DE DE4126190A patent/DE4126190A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| FR2665934A1 (en) | 1992-02-21 |
| DE4126190A1 (en) | 1992-03-12 |
| GB2247288B (en) | 1995-03-22 |
| FR2665934B1 (en) | 1996-02-23 |
| GB9116980D0 (en) | 1991-09-18 |
| GB2247288A (en) | 1992-02-26 |
| KR920004216A (en) | 1992-03-27 |
| JPH0491835A (en) | 1992-03-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |