Machine element or mechanism – Gearing – Adjustable
Patent
1998-02-19
2000-01-18
Graysay, Tamara L.
Machine element or mechanism
Gearing
Adjustable
475162, 101248, F16H 3500, B41F 13008
Patent
active
060149078
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to an adjusting device for providing changes of the angle of rotation between two rotary elements, which are driving and driven, respectively, and which under normal operation conditions shall be driven at one and the same rotary speed, comprising on one hand a first gear unit with a frame body, the first gear unit acting between the elements and being co-rotatively connected with one of said elements, in order to accompany it during rotation, input and output members being rotatable relative to the first gear unit in order to, when necessary, readjust or differentiate the angle of rotation between the elements, and on the other hand a second gear unit arranged to cooperate with an adjusting shaft that is rotatable between a given, not moving rest position during said normal operation conditions, and another position, the shaft during such rotation activating the second gear unit in order to transfer to one of the rotary members of the first gear unit a relative motion of the angle of rotation, which motion after a gear reduction by means of this gear unit provides for a restricted change of the angle of rotation between said driving and driven elements via the other rotary part.
1. Background of the Invention
In some fields of mechanical engineering, there is a need of fine adjustment of the positioning of the angle of rotation between two elements or shafts, which are driving and driven, respectively. This is the case for, e.g., printing machines in which a plurality of cylinders are normally driven synchronously by means of a main driving cylinder or shaft, for instance via bevel gear drives, external toothed transmission gears or gear belt transmissions. Now and then during operation, the need may arise of performing small corrections of the positions of the driven cylinders relative to the main driving cylinder, either in regard to the speed, for instance for fine-adjusting the tension in a continuous paper passing through the machine, or in regard to the adjustment of the angle of rotation of the individual cylinders in order to guarantee an accurate accordance between different printings on the continuous paper in consecutive cylinders. In both these cases, there are pronounced wants for the possibility of making a coarse adjustment within the range of 360.degree., followed by fine adjustments within a restricted region of angles of rotation, but with a very high resolution. Thus, an imaginary point on the envelope surface of the individual printing cylinder shall preferably be capable of being readjusted by a distance that amounts to a few millimeters, with a resolution of a few microns.
2. Prior Art
Previously known adjusting devices for the fine adjustment of cylinders in printing machines (e.g., of the type being commercially available under the denominations Tandler PD2, Conic HD and Harmonic Drive HDUA, respectively) have the general inconvenience that the driving cylinder or shaft has to be geared down before the fine adjustment of the driven cylinders can be made, to thereafter be geared up to full rotary speed, after having attained the desired position. This leads to considerable power losses and a troublesome release of heat. Furthermore, the accuracy of the fine adjustment is mediocre, at least as long as the device comprises merely two gear steps to guarantee the desired compactness.
An adjusting device of the initially generally described type is previously disclosed in WO 94/23223 (see also DE 43 10 158). It is true that in practice, this construction has the task of, when needed, making possible a differentiation of the rotary speeds of two output shafts or elements which are driven by a common axle, but in theory it could be modified for an application in a printing machine, i.e., in such a way that the angle of rotation of one single element is readjusted relative to a main driving element. According to this known construction, the first or primary gear unit consists of a cycloidal gear and the secondary gear unit of a planet
REFERENCES:
patent: 4286476 (1981-09-01), Stiff
patent: 4363270 (1982-12-01), Ury et al.
patent: 5123300 (1992-06-01), Himmelein et al.
patent: 5651314 (1997-07-01), Gentle
Graysay Tamara L.
Joyce William C
Scandrive Control AB
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