Bearings – Linear bearing – Recirculating
Reexamination Certificate
1999-11-24
2001-09-11
Hannon, Thomas R. (Department: 3682)
Bearings
Linear bearing
Recirculating
C384S051000
Reexamination Certificate
active
06287005
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a roller guiding apparatus for use in linear guides and the like of various industrial machines such as machine tools and so on.
In order to cope with this problem, in case of a rolling guide apparatus employing balls, the ability of attenuating or damping vibrations during the sliding and rolling movement of the balls is enhanced by positively utilizing differential slips of the balls caused by differences in the ball diameter in the center and the periphery of their contacting portions (see Japanese Patent Application Laid-Open No. H07-35136 for example).
In the case of balls used as rolling members, however, a rolling guide apparatus is sometimes liable to have an insufficient load-bearing capacity when applied to heavy machine tools, large-sized machines and so on.
On the other hand, rollers may be used in place of balls, and in this case, rollers of a cylindrical shape can provide an increased load-bearing capacity but do not have self-alignment and differential slips like balls, so no satisfactory vibration-damping capability can be expected.
SUMMARY OF THE INVENTION
In view of the above, the present invention is intended to obviate the above-described problems of the prior art and has for its object to provide a novel and improved roller guiding apparatus of the character described above which employs rollers having high rigidity as compared with balls and which has excellent self-alignment and vibration-damping capability as well.
In order to achieve the above object, according to the present invention, there is provided a roller guiding apparatus comprising:
an elongated traveling rail having a roller-rolling surface formed thereon;
a movable body having a roller-rolling surface formed in opposition to the roller-rolling surface of said traveling rail; and
a multitude of rollers interposed between the opposed roller-rolling surfaces of said traveling rail and said movable body:
wherein said rollers are each formed with a pair of arc-shaped portions having a diameter gradually decreasing from a central portion thereof toward opposite ends thereof, and
wherein each of said roller-rolling surfaces has a pair of first regions corresponding to said arc-shaped portions of each of said rollers, said first regions being each formed into an arc surface having a radius of curvature slightly greater than that of a corresponding arc surface of each roller such that each roller can be in contact at its opposite side arc surfaces with the corresponding arc surfaces of said opposed roller-rolling surfaces to thereby cause a differential slip therebetween.
With this arrangement, using as rolling members the rollers each having the opposite side arc-shaped portions provides for an increased length of contact between each roller and the opposed roller-rolling surfaces in comparison with balls, so that the load-carrying capacity of the apparatus for supporting a load applied thereto can be increased and excellent self-alignment can be obtained as well.
Moreover, during rolling, the rollers are in contact at their opposite side arc-shaped portions with the opposite side arc surfaces of said opposed roller-rolling surfaces to thereby cause differential slips therebetween, thus increasing the vibration-amping capability of the apparatus due to the resultant sliding frictional resistance.
in a preferred form of the invention, the central portion of each of said rollers comprises a central cylindrical portion of a cylindrical configuration. With this construction, it is easy to fabricate the rollers and perform measurements thereof as well.
In addition, when applied by a light load, the rollers being in contact at their central cylindrical portion with the opposed roller-rolling surfaces can travel in a smooth and light manner without causing differential slip, whereas when applied by a heavy load such as during a cutting operation and the like, the rollers are placed in contact at their opposite side arc-shaped portions with the opposite side arc surfaces of the roller-rolling surfaces, so that there arise differential slips therebetween, thus enhancing the vibration-damping capability of the apparatus.
In another preferred form of the invention, each of said roller-rolling surfaces has a second region corresponding to said central cylindrical portion of each roller, said second region comprising an arc-shaped surface contiguous to said opposite side arc surfaces of each roller-rolling surface. With this construction, when acted by a light load, the opposite ends of said central cylindrical portion of each roller are placed into point contact with the arc-shaped surface of the second region, thus ensuring smoother and lighter movements of the rollers.
Preferably, the second region of each of said roller-rolling surfaces comprises a flat linear portion. With this construction, the area of contact between each roller and the roller-rolling surfaces becomes great, increasing the load-bearing capacity of the apparatus.
On the other hand, the central portion of each of said rollers may comprise a central arc-shaped portion. This serves to enhance the self-alignment of the rollers.
In a further preferred form of the invention, each of said roller-rolling surfaces has a second region which corresponds to the central arc-shaped portion of each roller and which has a radius of curvature slightly greater than that of the central arc-shaped portion of each roller. This construction serves to further enhance the self-alignment of the rollers.
In a still further preferred form of the invention, each of said roller-rolling surfaces has a second region which corresponds to the central arc-shaped portion of each roller and which has a radius of curvature substantially equal to that of the central arc-shaped portion of each roller. With this construction, the load-bearing capacity and the vibration-damping capability of the apparatus can be increased.
Preferably, each of said opposed roller-rolling surfaces consists of a pair of opposite side arc surfaces so that each roller is in contact at its opposite side arc-shaped portions with the opposite side arc surfaces of the opposed roller-rolling surfaces at four points. With this construction, each roller contacts the opposite side arc surfaces of each roller-rolling surface at two points, thus increasing the load-bearing capacity of the apparatus in comparison with the case in which each roller contacts each roller-rolling surface at one point.
Also, in this case, the points of contact of the opposed roller-rolling surfaces with respect to each roller when lightly loaded are bottoms of the opposite side arc surfaces of the roller-rolling surfaces, whereas when heavily loaded, the points or portions of contact expand from the respective bottoms of the two arc surfaces of the roller-rolling surfaces toward the opposite sides thereof, thereby increasing the vibration-damping capability.
Preferably, said rollers on said traveling rail at an upper and opposite sides thereof are held in place and connected with each other by means of corresponding roller connectors, respectively. With this construction, during rolling movements of the rollers, the central axis of each roller can be precisely guided in a direction perpendicular to the traveling direction of the movable body, i.e., perpendicular to the longitudinal direction of the traveling rail.
The above and other objects, features and advantages of the present invention will become more readily apparent from the following detailed description of preferred embodiments of the invention when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4702622 (1987-10-01), Teramachi
patent: 5005988 (1991-04-01), Lyon
patent: 5836701 (1998-11-01), Vranish
Brinks Hofer Gilson & Lione
Hannon Thomas R.
Teramachi Hiroshi
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