Joints and connections – With fluid pressure responsive component
Patent
1997-07-24
1999-01-05
Kim, Harry C.
Joints and connections
With fluid pressure responsive component
403373, 403 5, 279 403, F16B 202
Patent
active
058554467
DESCRIPTION:
BRIEF SUMMARY
The present invention generally relates to a hydraulic clamp bushing of the type which comprises a double walled sleeve, a closed pressure chamber between said sleeve walls, a hydraulic pressure medium trapped in said chamber between the sleeve walls and means for pressurizing the pressure medium, and in which one of the sleeve walls, or both walls, is/are formed so as to expand radially outwards and/or inwards when the pressure medium is pressurized, whereby the clamp bushing becomes clamped to a shaft, a hub or another means, in particular against a rotatable shaft. A typical clamp bushing of said type is shown for instance in the U.S. Pat. No. 4,093,052 (inventor Curt G Falk).
Clamp bushings of this type are well suited for connecting a hub to a bushing or a hollow shaft for transmitting axial forces and/or rotary torques, and they can for instance be used for mounting of rotary tools on a machine spindle. In some cases there may appear problems with such conventional clamp bushings for the reason that the sleeve walls expand in a bow form when the hydraulic pressure medium is pressurized, thereby providing an almost point formed line of contact of the wall against the shaft during the initial phase of the pressurization, and this may make the clamp bushing become obliquely mounted on the shaft. Clamp bushings of the said type generally also have a contact surface to engage the shaft and/or the hub which is shorter than the total length of the bushing. For reducing the risque that the clamp bushing is mounted obliquey located on the shaft, and for providing a high torque transmission ability such clamp bushings therefore often are formed with relative great axial length. Long clamp bushings generally give small radial and axial wobbling.
In many cases it is, however, necessary that the(clamp bushing, for technical reasons, be made relatively short, and in such cases there may appear problems with axial and radial wobbling of the tool which is mounted on the shaft. Such problem may for instance appear when tools and other means having a relatively great diameter are mounted on a machine spindle by means of a relatively short clamp bushing, for instance upon mounting of rotary knives, cutting rolls, saw blades, grinding wheels etc. on a machine spindle. Special problems may appear for instance in the type of cutting apparatus, in which a plate formed material is feed in between two overlapping cutting rolls which cut or shear the plate into strips. For obtaining a good cutting result it is important that the overlapping cutting rolls are located very close to each other and that the cutting knives or rolls are subjected to a very minimum of wobbling. Even a very slight axial wobbling results in a bad cutting result and a risque that the cutting rolls collide, what in turn leads to a quick wear of the cutting rolls.
A fixed hub or a fixed ring which is moved on a shaft may, at a maximum, be mounted obliquely as shown with the dotted lines in FIG. 8, which figure is an illustration of the background of the invention. In said figure the following symbols are used: of a mm)
If the values of X and .DELTA.D are relatively small as compared with B and D.sub.1 the following geometrical relationship is obtained:
Thus, said geometrical relationship gives a maximum wobbling which is a product of the play .DELTA.D and the out diameter D.sub.1, divided by the width B.
Tests have shown that the following formula is obtained when using a bushing of conventional hydraulic type: is reduced by a factor kn when a hydraulic clamp bushing is used.
The reason for appearance of wobbling when using relatively short clamp bushings of the above mentioned type can be looked for in the fact that the radially expandable sleeve or sleeves expand in bow form when the pressure medium is pressurized (compare right half of figure), and this means that there is an almost point formed line of contact between the sleeve and the shaft or the spindle at the centre of the sleeve during the initial phase of the pressurization, and that the conta
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patent: 3507507 (1970-04-01), Tobler et al.
patent: 3626506 (1971-12-01), Spieth
patent: 3663027 (1972-05-01), Klipping
patent: 4264229 (1981-04-01), Falk et al.
patent: 4531856 (1985-07-01), Gebelius
patent: 4940354 (1990-07-01), Holderegger et al.
patent: 5079836 (1992-01-01), Swars
patent: 5102253 (1992-04-01), Conti
ETP Transmission AB
Kim Harry C.
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