Spring devices – Bendable along flat surface – Flexural support
Reexamination Certificate
1998-06-05
2001-02-20
Graham, Matthew C. (Department: 3613)
Spring devices
Bendable along flat surface
Flexural support
C267S165000
Reexamination Certificate
active
06189875
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a positioning device comprising an X-beam on which a carriage provided with a positioning head is movable in an X-direction, a first Y-beam on which a first carriage is movable in a Y-direction, a second Y-beam on which a second carriage is movable in the Y-direction, while a first end of the X-beam is connected to the first carriage of the first Y-beam by means of a first coupling, and a second end of the X-beam is connected to the second carriage of the second Y-beam by means of a second coupling such that the X- and Y-beams are oriented in an H-arrangement, said device further comprising drive means for separately driving the carriages on the Y-beams and the carriage with the positioning head on the X-beam.
Such a positioning device is known from EP-B1-0 109 718. The couplings between the X-beam and the carriages on the Y-beams are formed therein by pivot shafts oriented in a Z-direction which connect the parts to one another with rotation possibility. To enable a rotation of the X-beam about the Z-axis, one end of the X-beam is constructed as a sliding coupling in the X-direction. A positioning device is used for accurately positioning the one part, which is supported by the positioning head of the carriage on the X-beam, with respect to another part, which is supported by a machine part which is usually stationary. This is, for example, a component which is to be placed on a printed circuit board. The ever continuing miniaturization of components leads to ever stricter requirements being imposed on the accuracy with which components are to be positioned with respect to one another.
SUMMARY OF THE INVENTION
It is an object of the invention to improve the accuracy of the device.
The positioning device is for this purpose characterized in that the first coupling is formed by two mutually perpendicular leaf springs which extend approximately in the X-direction and the Y-direction, respectively, one end of each leaf spring being fastened to the first end of the X-beam and the other end of each leaf spring being fastened to the first carriage of the first Y-beam, the line of intersection of said leaf springs forming an axis of rotation which extends in the Z-direction, the second coupling is formed by only one leaf spring which extends approximately in the Y-direction, one end of said leaf spring being fastened to the second end of the X-beam and the other end to the second carriage of the second Y-beam, said leaf spring having a comparatively high stiffness in the Y-direction and a comparatively low stiffness in the X-direction.
The first coupling is a kind of cross-spring hinge. The (imaginary) line of intersection of the two leaf springs forms a very accurate axis of rotation about which the X-beam can perform a rotation relative to the carriage on the first Y-beam. The stiffness in the X-direction is comparatively high and in the Y-direction comparatively low for the leaf spring of the first coupling which extends approximately in the X-direction, whereas this is exactly the opposite for the leaf spring which is perpendicular thereto. To render possible a rotation of the X-beam, which will usually relate to very small rotations, the leaf spring of the second coupling must have a comparatively low stiffness in the X-direction and a comparatively high stiffness in the Y-direction. The stiffness in the Z-direction is obviously also high for all leaf springs. The great advantage of the leaf spring couplings is that they are absolutely free from play and free from friction. The stiffness against rotation about the longitudinal axis of the X-beam is high because the leaf springs extend in the Y-direction. The construction of the X-beam in relation to the Y-beams is statically fully defined. The leaf spring of the second coupling also allows for a change in length of the X-beam in the X-direction caused by temperature changes.
Another great advantage is that the orientation around the Z-axis of a component to be positioned, such as a component on a printed circuit board, can be very accurately adjusted. It is possible to have the X-beam undergo a small angular rotation in that, for example, one of the carriages on the Y-beam is caused to continue a little farther or less far, whereby a fine angular correction of the component is achieved.
Preferably, the X-beam and the Y-beams lie substantially in one and the same plane. As a result, the center of gravity of the total moving construction (the X-beam plus the carriages plus the positioning head) lies approximately in the plane in which the driving forces are exerted. This also enhances the positioning accuracy.
REFERENCES:
patent: 2793028 (1957-05-01), Wheeler
patent: 2932482 (1960-04-01), Dickie
patent: 2947067 (1960-08-01), Vice et al.
patent: 2966049 (1960-12-01), Ormond
patent: 4183627 (1980-01-01), Camerik
patent: 5315890 (1994-05-01), Long
patent: 1120711 (1961-12-01), None
patent: 0109718 (1984-05-01), None
Biren Steven R.
Graham Matthew C.
U.S. Philips Corporation
LandOfFree
Positioning device with H-drive having spring coupling... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Positioning device with H-drive having spring coupling..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Positioning device with H-drive having spring coupling... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2577221