Joints and connections – Member deformed in situ – Deformation occurs simultaneously with assembly
Reexamination Certificate
1999-04-21
2001-09-25
Knight, Anthony (Department: 3629)
Joints and connections
Member deformed in situ
Deformation occurs simultaneously with assembly
C403S274000
Reexamination Certificate
active
06293725
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a collet designed to accommodate varying thrust loads in a mechanical coupling. The application also relates to a method in accordance therewith.
DESCRIPTION OF THE RELATED ART
More specifically, the invention relates to a two piece collet, which is axially compressed to expand in a radial direction. In the expanded position, the collet has a flexibility for biasing fixation of elements, supported on a spindle in a mechanical assembly. The invention also provides a method for a resilient, axial fixation of elements supported on the spindle.
Collets of the type referred to are often used in gear boxes, e.g. in an auto gear transmission, where the collet is applied for axially holding gears which are supported on a splined axle. In this application, the collet must be designed to accommodate substantial thrust loads, in the range of about 30-50 kN, e.g., and still having expected axial and radial deformation properties so as not to collapse, but rather to display a certain flexibility also after the initial deformation on assembly. The collet is applied between gears or in contact with a supporting surface, but should be free to rotate on the spindle so as not to cause undue wear. In operation, varying thrust loads may be applied to the collet, as the result of shifting torque.
A prior art collet for application in gear boxes is a one piece ring-shaped element (see
FIGS. 1
a
and
1
b
) designed with a V-shaped notch or depression, running centrally in the inner periphery of the collet for controlling the radial expansion.
A drawback in this collet is the limited property of flexibility in expanded position. This drawback may be explained from the V-shaped depression acting more or less as a breaking or folding notch.
Another drawback of the prior art collet is the difficulty in production of consistently achieving an optimum dimensioning of the notch, taking into account a subsequent treatment in terms of stress-relieving heating to control the hardness of the material.
Yet another drawback of the prior art, one piece collet is its susceptibility for radial contraction of the ends upon axial compression and deformation, causing the collet to be axially and rotatably locked to the spindle. In case of a gear transmission, the locked collet will cause wear on the spindle and on the engaging gears.
SUMMARY OF THE INVENTION
An object of this invention is therefore to provide a collet, specifically but not exclusively for above said application, which is designed to operate with desired resilient properties within a present load interval.
Furthermore, an object is to provide a collet which is not dependant on subsequent material treatment to achieve the desired properties, whereby the drawbacks of the prior art collet are eliminated.
Briefly, the invention relates to a collet for accommodating varying thrust loads in a mechanical coupling, comprising a first cylinder shaped sleeve formed to overlap in coaxial relation with a second sleeve, said first sleeve having a cylinder wall designed for deformation under radial expansion when the sleeves are axially compressed upon assembly on a spindle where the collet is applied for a biasing, axial fixation of gears which are supported on the spindle. Said second sleeve is formed in one end with a conical transition section rising from a cylinder section and adjoining an end section of greater radius in the second sleeve, the conical transition section having a slope angle relative to a longitudinal axis, wherein the first sleeve, upon axial compression of the sleeves, is caused to be plastically deformed and to expand in radial direction under guidance of the conical section such that an arcuate flange is formed in the first sleeve and acting upon the sloping surface of the conical section, thereby providing a resilient, axial fixation of the gears when the collet is maintained within or near a yielding, axial pressure.
By introducing a collet comprising the above said features, there is also suggested a method of providing a resilient, axial fixation of gears supported on a spindle in a mechanical assembly, wherein a two piece collet is designed to be inserted between gears, or between gears and a support surface. The collet is axially compressed and caused to expand in radial direction under an axial load which is applied to the ends of the collet, wherein the radial expansion is controlled in such way that the collet is maintained within or near a yielding pressure in the assembly.
REFERENCES:
patent: 2185725 (1940-01-01), Elliott
patent: 2466057 (1949-04-01), Somma
patent: 3265413 (1966-08-01), Currie
patent: 3837755 (1974-09-01), Benoit et al.
patent: 4053247 (1977-10-01), Marsh, Jr.
patent: 4172621 (1979-10-01), Yoshida
patent: 4508321 (1985-04-01), Morimoto
patent: 5000612 (1991-03-01), Swars
patent: 5090837 (1992-02-01), Mower
patent: 5431379 (1995-07-01), Takagi
patent: 5685663 (1997-11-01), Sadri
patent: 5718131 (1998-02-01), Bobbitt, III
Bochna David E.
Knight Anthony
Young & Thompson
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