Electrical generator or motor structure – Dynamoelectric – Linear
Reexamination Certificate
2000-08-07
2001-09-04
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Linear
C409S201000, C409S216000, C409S235000, C901S041000, C074S490030
Reexamination Certificate
active
06285098
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a linear drive comprising a carrier and a carrier housing on which the carrier is supported such that it is longitudinally movable, and drive elements provided on said carrier and said carrier housing and used for producing a relative movement between said carrier and said carrier housing.
BRIEF DESCRIPTION OF THE PRIOR ART
Such linear drives are primarily used in machine tools for producing a feed motion between a tool and a workpiece. In particular, such linear drives are used in the still young field of machine tools with parallel structures. Recently, in particular hexapod machine tools have become known in the case of which the actual machining module is supported on a machine frame via six struts of adjustable length. By purposefully varying the strut lengths, feed motions of the tool to the workpiece can be realized in all six spatial degrees of freedom, i.e. three translatory degrees of freedom and three rotational degrees of freedom. A machine tool of this type is known e.g. from US-A-5 401 128, which discloses linear drives of the type mentioned at the start for the struts.
Other hexapod structures are known from German patent applications P 196 36 100.1 and P 196 36 099.4 of the applicant of the present application.
Nowadays, modern machine tools have to fulfil high requirements on the force absorbing ability, feed and production accuracy and dynamic behaviour. Efficient control means suitable for realizing new machining strategies, such as high-speed machining processes or the production of complicated three-dimensional shapes, require, for optimum utilization, new drive concepts which can only be realized to a limited extent by conventional drive elements.
In the field of linear drives, for example, spindle drives have been known for a long time whose performance is, however, limited by the conversion of a rotary movement into a linear movement. The direct linear drives which have been used up to now for moving machine tool tables or carriages can, due to their voluminous structural design, only be used to a limited extent for the above-mentioned machining strategies.
Also the electric linear motor, which is known from U.S. Pat. No. 5,401,128 and which is there used as a hexapod machine tool strut of adjustable length, is in need of improvement, especially as far as its dynamic behaviour is concerned.
SUMMARY OF THE INVENTION
It is therefore the object of the present invention to provide a hexapod machine tool equipped with a compact, stiff strutting structure and relative length adjustment for the struts, which is particularly suitable for use as a high-speed machine tool.
This permits the realization of a particularly light but still stiff structure allowing, due to its small mass, high accelerations and decelerations and increasing therefore the maximum possible production speed and production accuracy in comparison with the hitherto known hexapod machine tool.
In addition, the length adjustment structure of the struts with a respective linear drive can now also be implemented as an extremely slender component so that there will be a greater freedom of design for arranging a plurality of linear drives, a fact which is of interest in the area of the machining module in particular in the case of comparatively small hexapod machine tools.
The drive elements of the linear drive, i.e. the respective magnets and coils, are provided on the carrier side on inner surfaces of the carrier in a particularly space-saving manner.
For optimally compensating the forces and moments acting on the carrier due to the drive elements and for improving the running properties of the carrier in its support on the housing, the drive elements of the carrier are provided in pairs and arranged on respective opposed surfaces of the carrier.
A particularly compact embodiment will be obtained when the drive elements, i.e. the respective coils and magnets of the carrier housing, are arranged within the open areas of the cross-sectional profile of the carrier in such a way that they fill almost the whole residual free space of the cross-sectional profile; sub-areas of these drive elements may definitely extend beyond the carrier. This also applies to structural designs in the case of which sub-areas areas of the drive elements of the carrier housing project into the open areas of the cross-sectional profile of the carrier.
In order to provide a carrier structure which is particularly light but, nevertheless, very stiff, the carrier comprises two U-shaped profiled bodies which are arranged such that their bottom sides face each other. Between these bottom sides a lightweight supporting element is arranged in the central area of the carrier, i.e. in the region of the smallest areal moments of inertia, said lightweight supporting element being provided with a plurality of empty spaces, through holes or openings.
REFERENCES:
patent: 3579001 (1971-05-01), Pelenc et al.
patent: 4247794 (1981-01-01), Jooss et al.
patent: 4831290 (1989-05-01), Clauss et al.
patent: 5401128 (1995-03-01), Lindem et al.
patent: 5486727 (1996-01-01), Heidelberg et al.
patent: 768146 (1997-04-01), None
patent: 2194907 (1988-03-01), None
Patent Abstracts of Japan, vol. 18, No. 320 (E-1563) of Jun. 17, 1994 & JP 06070534A of Mar. 11, 1994 (Yaskawa Electric Corp.).
Patent Abstracts of Japan, vol. 97, No. 10 of Oct. 31, 1997 & JP 09150334 of Jun. 10, 1997 (Toyodo Mach Works Ltd.).
Patent Abstracts of Japan, vol. 17, No. 675 (M-1526) of Dec. 13, 1993 & JP 05228761A of Sep. 7, 1993 (Canon Inc.).
Konvicka Jan
Nestler Rainer
Wieland Frank
Fraunhofer-Gesellschaft zur Forderung der angewandten Forderung
Jones Judson H.
Laubscher & Laubscher
Ramirez Nestor
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