Joints and connections – Interfitted members – Rotary binding cam or wedge
Reexamination Certificate
1999-01-28
2001-06-19
Browne, Lynne H. (Department: 3629)
Joints and connections
Interfitted members
Rotary binding cam or wedge
C403S350000, C403S348000, C403S371000
Reexamination Certificate
active
06247870
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device which can be used to fit in a reversible way a mechanical component equipped with a cylindrical hub onto a cylindrical shaft, and in particular to a device that allows a tractor roller for yarn, usually of a plastic material, to be fitted onto a metal shaft which is circular in section.
2. Background Art
Devices have been known some time that allow the reversible fitting of mechanical components with conical bores onto cylindrical shafts by means of a split or bushing with cylindrical internal surface and conical external surface. A groove on the external surface of the bush allows the same bush to be fixed to the hub by screws or grub-screws, while a keyway is cut into the internal surface of the bush and the external surface of the shaft to allow the bush to be keyed to the shaft.
However, the laboriousness of the operation to produce the keyways and the play that results, with time, between hub and shaft, make this solution unadvisable, particularly if the mechanical component is of plastic material.
Friction-fitting devices have also been known for fitting mechanical components with cylindrical bores, comprising at least one pair of conical split bushes, which bear respectively on the hub and on the shaft involved in the fitting.
To allow the transmission of a torque via friction, these devices must develop considerable radial forces that bear against the hub of the mechanical component. Therefore, such fitting devices require mechanical components with hubs that are very large in relation to the shaft diameters. They could also present dismantling problems due to the two bushes jamming onto the surfaces with which they are in contact.
An alternative technique widely used particularly for fitting yarn tractor rollers onto metal shafts consists of the provision of a plurality of threaded through-holes disposed radially along the external surface of the roller to accommodate pressure screws, which exercise a force on one piece by means of their end while the screw stem is screwed into a threaded hole in the other piece. When tightened the screws hold the shaft securely creating a detachable coupling of the roller to the same shaft.
However, this solution, which is adequate for the transmission of low torques between shaft and hub, has the drawback that it is difficult to center the mechanical component precisely on the shaft and therefore does not allow a correct balancing of the roller in motion. A further, but no less significant, drawback is that the screw holes accommodating the screws could damage the same yarn by acting as an impediment to the free sliding of thread.
OBJECTS OF THE INVENTION
An object of the present invention is to provide a device for the reversible fitting of mechanical components—in particular of mechanical components subject to low torques—to cylindrical shafts that is self-centering, which does not involve the presence of roughness on the external surface of the roller and which is simple to produce and operate.
SUMMARY OF THE INVENTION
This object is achieved by the present invention which relates to a device for the fitting of mechanical components equipped with a cylindrical hub onto shafts of circular section, comprising at least one hub end collar that includes a substantially elliptical seat or opening, and a bush so shaped as to engage in said elliptical seat said bush having an elastically deformable external side surface that presents a first size, measured perpendicularly to the axis of the same bush, which falls between the minor diameter and the major diameter of said elliptical seat and a second size, measured perpendicularly to the same axis, which is less than the minor diameter of the elliptical seat.
Preferably the bush of the device according to the invention presents at least one cutout that confers elasticity on it and that defines the said second dimension.
This bush can thus be inserted into the elliptical seat in an unlocked position in which the first size corresponds to the major diameter of the elliptical seat, thereafter it is rotated and forced so that its greater size results close to the minor diameter of said elliptical seat. In this second position not only the major size of said bush, but also the cutout gap—and therefore the cross-sectional area of the bush perpendicular to the axis of the same bush—is reduced.
Thus, arranging the shaft internally in both the cylindrical hub and the bush and positioning the bush in the elliptical seat of the hub end collar, thereafter rotating the same bush in said seat until it is forced to reduce said cutout gap(s), a locking, i.e. a fitting, of the shaft to the mechanical component is thus achieved.
A preferred embodiment of the invention will be described, by way of example and not of limitation, with reference to the attached drawings in which:
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patent: 4602411 (1986-07-01), Brown
patent: 4632437 (1986-12-01), Robson et al.
patent: 4738561 (1988-04-01), Röttger
patent: 5048998 (1991-09-01), Viets
patent: 5356183 (1994-10-01), Cole
patent: 5460458 (1995-10-01), Caceres
patent: 5931598 (1999-08-01), Wang
patent: 34 41 457 (1986-05-01), None
patent: 399 265 (1909-02-01), None
patent: 2 151 713 (1985-07-01), None
Bochna David Eric
Browne Lynne H.
Millen White Zelano & Branigan P.C.
Scaglia S.p.A.
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