Bearings – Linear bearing – Recirculating
Reexamination Certificate
2000-06-08
2002-01-15
Morano, S. Joseph (Department: 3617)
Bearings
Linear bearing
Recirculating
C384S043000, C384S044000, C104S106000, C104S119000
Reexamination Certificate
active
06338573
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART STATEMENT
1. Field of the Invention
The present invention relates to a universal guide device that is used in sliding portions of various machine tools, part-conveying systems, and so on and is capable of guiding a movable object or material over a conveyance path containing both straight and curved regions.
2. Related Art
For example, on a product line or the like in a plant, if all processing stations are arranged linearly, then no problems will take place. However, depending on the space of the plant in which a machine is installed or on the contents of the processing performed in processing stations, it may be necessary to change the direction of conveyance of materials to be processed between two adjacent processing stations. In this case, it is customary to use a pallet changer or the like to achieve a change in the direction of conveyance. Unfortunately, additional space and cost for installing the pallet changer or the like are necessary.
Known means for modifying the direction of conveyance of materials or objects without using a pallet changer include universal guide devices (as described in Laid-open, unexamined Japanese patent application Nos. 293319/1988 and 50333/1994) capable of guiding materials continuously along a path including both straight and curved lines and curved guide devices (as described in Laid-open, unexamined Japanese patent application No. 186028/1988) capable of guiding materials continuously along an annular path.
These universal guide devices and curved guide devices each comprise a track rail, a slider, and a number of balls. The rail forms longitudinally extending surfaces on which the balls roll. The slider is mounted to span the rail. Load-rolling surfaces opposite to the rolling surfaces of the rail and an endless circular path for the balls are formed on and in the slider. The endless circular path includes the load-rolling surfaces. The balls roll in the endless circular path of the slider and between the rolling surfaces of the rail and the load-rolling surfaces of the slider carry a load. The slider moves along the rail in response to rolling movement of the balls.
In the former universal guide device, each load-rolling surface of the slider is partitioned into straight load regions formed linearly and curved load regions shaped into an arc in conformity with the curvature of the rail. In each straight load region of the rail, the load acting on the slider is carried by the balls rolling in the straight load region. In each curved region, the load is carried by the balls rolling in the curved region. As a result, even if straight and curved regions are intermingled on the track rail, the slider can move along the rail through the straight and curved regions continuously.
In the latter curved guide device, the track rail is shaped into an arc having a given curvature. The load-rolling surface of the slider is shaped into an arc in conformity with the curvature of the rail. All the balls interposed between the load-rolling surface of the slider and the rolling surface of the rail roll on while carrying the load acting on the slider. In consequence, the slider can make a curved motion along the rail.
In these conventional universal guide devices and curved guide devices, the load-rolling groove or race in the slider is shaped into an arc in conformity with the curvature of the track rail to permit movement of the slider through the curved region of the rail. Therefore, it has been necessary to machine the load-rolling surface in conformity with the curvature of the rail. Consequently, it has been impossible to directly use the sliders of conventional mass-produced linear guide devices that are available in the market. Hence, the production cost is increased. Furthermore, a different slider is necessary for each different curvature of track rail. Therefore, it is laborious to machine the sliders and to manage finished products.
Where the load-rolling surface of a slider is machined into an arc, the direction of bending of the curved region of a track rail is limited to one direction, left or right. Although it is possible to transport materials and objects annularly, it is impossible to convey materials along a track including two curved regions bent in different directions such as an S-shaped track.
On the other hand, in a path between two adjacent machining stations on a product line, if materials can be transported, no problems take place. It is considered that capability to carry very large loads is not necessary in curved regions of the rail. However, during a machining process, a machining force acting on a material needs to be sustained reliably by a guide device. Straight regions of the rail are required to have ability to carry a larger load than curved regions. In the aforementioned conventional universal guide device, the load-rolling surface formed on the slider is divided into straight and curved load regions. Therefore, the straight regions of the rail have decreased ability to sustain loads. Consequently, a machining force acting on materials cannot be sufficiently sustained.
Where materials are actually transported using such universal guide devices, it is necessary to construct a moving table device from two or more universal guide devices in order to transport such materials stably. In particular, two track rails are placed parallel to each other. Plural sliders are mounted to each track rail. A table is mounted so as to span all of these sliders. The materials to be transported are placed on this table.
Where the table is moved only through a linear region or only through a curved region, if all the sliders are mounted directly to the table, no problems take place. The table can be smoothly moved. However, where the table is moved from a curved region to a straight region or vice versa continuously, if all the sliders are directly mounted to the same table, the configuration of one slider relative to the track rail is restricted by other sliders. This makes it difficult to move the table smoothly. Accordingly, where plural universal guide devices of the construction described above are used to construct the moving table device, it has been impossible to mount the sliders directly to the table.
OBJECTS AND SUMMARY OF THE INVENTION
In view of the foregoing problem, the present invention has been made. It is an object of the present invention to provide a universal guide device which can directly use sliders heretofore employed in linear guide devices and which do not need different sliders for each different radius of track rail and thus can be fabricated at lower cost than conventionally.
It is another object of the invention to provide a universal guide device in which sliders can move through two curved regions of a track rail continuously along the rail even if the two curved regions are bent in different directions and in which the sliders can move from a straight region to a curved region or vice versa continuously without sacrificing the ability of the rail to sustain a load in the straight region even if the rail contains both straight and curved regions.
It is a further object of the invention to provide a moving table device comprising plural parallel track rails and plural sliders mounted to each track rail, the moving table device being characterized in that smooth movement of the sliders is assured even if a table is supported by the sliders that are four or more in number.
To achieve the objects described above, a universal guide device in accordance with the present invention comprises: a track rail including a straight region and a curved region shaped into an arc with a given radius of curvature and having ball-rolling surfaces on both its side surfaces, the ball-rolling surfaces extending longitudinally; a slider having a saddlelike cross section and mounted to span the track rail; load-rolling surfaces formed on the slider and located opposite to the rolling surfaces, respectively, of the rail; and an endless circular path for a number of balls. The circular path
Hoshide Kaoru
Kouchi Minoru
Michioka Hidekazu
Mochizuki Hiroaki
Jules Frantz F.
Morano S. Joseph
THK Co. Ltd.
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