Bearings – Linear bearing – Recirculating
Reexamination Certificate
1999-06-14
2001-04-03
Hannon, Thomas R. (Department: 3682)
Bearings
Linear bearing
Recirculating
C384S043000, C384S044000, C384S049000
Reexamination Certificate
active
06210039
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a linear motion guide device using rolling balls and to a table guide device using the linear motion guide device.
BACKGROUND ART
As examples of the conventional linear motion guide device of this type, for example, the devices disclosed in Japanese Patent Laid-Open Publication No. SHO 55-46045 and No. SHO 55-46046 are well known. That is, each of the devices comprises a track rail and a movable block having an L-shape in section, and the movable block further comprises a horizontal portion opposing to an upper surface of the track rail and a suspending portion opposing to one side surface of the track rail.
Two rows of rolling balls were disposed to be rollable between two opposing surfaces of the upper surface of the track rail and the horizontal portion of the movable block, and between two opposing surfaces of the one side surface of the track rail and the suspending portion of the movable block, respectively.
The conventional linear motion guide device of this type has a following contact-angle structure. Namely, in the two rows of rolling balls provided on the upper surface of the track rail, a contact angle line constituted by a line connecting the two contact points of the rolling balls to the ball rolling grooves corresponding to the respective ball rows is set to extend toward the track rail and is formed so as to incline toward a side of the suspending portion with respect to a vertical line passing a center of the rolling ball in a case of the ball row positioned close to the suspending portion side, while the other contact angle line in a case of a ball row positioned at the other side of the suspending portion is set to extend toward the track rail and is formed so as to incline toward an opposing side of the suspending portion.
In contrast, in the pair of rolling balls provided on the side surface of the track rail, a contact angle line constituted by a line connecting the two contact points of the rolling balls to the ball rolling grooves corresponding to the respective ball rows is set to extend toward the track rail and is formed so as to incline toward a side of the horizontal portion with respect to a horizontal line passing a center of the rolling ball in a case of the ball row positioned close to a side of the horizontal portion, while the other contact angle line in a case of a ball row positioned at the other side of the horizontal portion is set to extend toward the track rail and is formed so as to incline toward an opposing side of the horizontal portion.
Due to an employment of such contact-angle structure, a load-bearing capacity against loads to be applied from various directions including vertical and horizontal directions can be enhanced. In particular, it becomes possible to increase a supporting rigidity against a moment in a direction for rotating the movable block around the track rail.
In the prior art technics described above, however, since the supporting rigidity against the moment in the direction for rotating the movable block around the track rail is high, there were posed following problems. Namely, when the movable block in a state having a working error in attaching surfaces thereof is fixed to a table and then the track rail is fixed to a fixed bed, a misalignment is caused between the track rail and the movable block and an excessive force is applied to the track rail and the movable block, thus resulting in increasing of sliding resistance and promoting early wear of the ball rolling grooves and rolling balls per se. Such misalignment will be avoided by increasing working precision of the respective members of the device. However, the working precision has a limit itself and involves a cost increasing.
The present invention is achieved for solving the aforementioned problems and an object of the present invention is to provide a linear motion guide device and a table guide device using the linear motion guide device which has an automatic controllability and enables to realize a supporting structure having a high rigidity.
DISCLOSURE OF THE INVENTION
In order to achieve the afore-mentioned object, the present invention provides a linear motion guide device comprising:
a track rail having a rectangular-shape in section and at least one ball rolling groove formed respectively to an upper surface and one side surface of the track rail;
a movable block having a L-shape in section, comprising a horizontal portion provided with ball rolling grooves corresponding to ball rolling grooves formed to the upper surface of the track rail and a suspending portion provided with ball rolling grooves corresponding to ball rolling grooves formed to the one side surface of the track rail; and
a row of rolling balls disposed to be rollable between corresponding ball rolling grooves formed to the upper surface of the track rail and the horizontal portion of the movable block and between corresponding ball rolling grooves formed to the side surface of the track rail and the suspending portion of the movable block, respectively;
wherein each of the ball rolling grooves has a circular-arc-shape in section having a deep-groove shape having a groove depth set to approximately ⅓ to ½ of a diameter of the rolling ball.
According to the present invention, the movable block is formed in L-shape in section and has a supporting construction in which only the upper surface and one side surface of the track rail are supported by the horizontal portion and the suspending portion at a right angle, so that it becomes possible to increase a degree of freedom in a direction for inclining the horizontal portion and the suspending portion around a corner portion between the horizontal portion and the suspending portion. Therefore, even if the track rail and the movable block are formed with a working error or the device is formed with an error in a degree of parallelism between a mating surface to which the track rail is attached and a mating surface to which the movable block is fixed, a position of the movable block can be automatically adjusted and controlled by displacements of the contact points of the rolling balls rolling in the ball rolling grooves.
In addition, each of the ball rolling grooves is formed so as to have a deep-grooved shape. Therefore, even if the contact points of the rolling balls are displaced by the automatically controlling function, the rolling ball contacts to intermediate portions of an inner circumferential surface of the ball rolling groove, the intermediate portions being far deep positions from a side peripheral edge portion of the ball rolling groove. As a result, a load to be applied to the rolling ball can be dispersed and supported by the inner circumferential surface of the ball rolling groove, and there is no fear of edge-load being applied to the side peripheral edge portion of the ball rolling groove, thus achieving a high automatic controllability.
Further, the movable block is formed to be opened at one side thereof, so that the movable block can be subjected to a grinding work using a large-sized grinding stone to form the ball rolling grooves. In addition, even in a case of the deep-grooved type, the grinding work can be performed at a high efficiency, thus improving the productivity of the device.
Furthermore, the movable block is formed in an L-shape and has no under-cut portion, and the track rail is also formed in a simple rectangular-shape in section, so that the movable block can be easily formed by a drawing operation and the productivity can be improved.
In one aspect of this invention, there can be also provided a linear motion guide device in which a contact angle line constituted by a line connecting the two contact points of the rolling ball disposed between the corresponding ball rolling grooves formed to the horizontal portion of the movable block and the upper surface of the track rail is set to extend toward the track rail and is formed so as to incline toward a side of the suspended portion with respect to a vertical line passing a center of t
Armstrong, Westerman Hattori, McLeland & Naughton
Hannon Thomas R.
THK Co. Ltd.
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