The invention pertains to a clamping device for fixing a wheel rim of a vehicle wheel to a shaft of a balancing machine.
More particularly, the invention relates to a clamping device of the type such as described in the preamble of claim 1; e.g., of the type as described in DE-OS 1 928 054, which is incorporated herein by reference.
DE 28 07 343 A1 describes a clamping device in which the centering bolts that are referred to as pins in this publication contain a longitudinal cavity. Pins that are prestressed by means of springs are displaceably arranged in these longitudinal cavities, with the ends of said pins respectively protruding in the axial direction from the centering cone. A wheel rim of a vehicle wheel should be suspended on and consequently pre-centered on the ends of the pins such that the centering bolts can respectively engage into and center the mounting holes of a wheel rim with their centering cone when the clamping flange is tightened against the locating flange.
The centering bolts are connected to the clamping flange by means of screws such that they can be exchanged. Due to mounting tolerances as well as the resilience of the centering bolts, inaccuracies in the radial position of the centering cones on the ends of the centering bolts may occur such that a precise centering of a wheel rim is no longer possible.
This disadvantage becomes particularly evident if the rear ends of the centering bolts are provided with pins that can be inserted into different holes in the clamping flange in accordance with the different hole arrangements in wheel rims, e.g., as it is the case with another clamping flange that is available on the market (company pamphlet xe2x80x9cTypenspannflanschexe2x80x9d of the firm HAWEKA Auswuchttechnik Horst Warkotsch GmbH, 30928 Burgwedel, Impressum (e.g., reprint no.) 304-10/94-1000/2D). In this case, a certain play between the centering bolts and the clamping flange is unavoidable, i.e., centering errors are also unavoidable.
A clamping device of the type described in the preamble of Claim 1 is known from the initially mentioned DE-OS 1 928 054. In this case, openings are arranged in the locating face of the locating flange, with the inside dimension of said openings corresponding to the diameter of the pins, and with the average radial distance of said openings from the rotational axis of the shaft of the balancing machine corresponding to the radial distance of the centering bolts from the rotational axis of the shaft of the balancing machine. However, this known clamping device is not suitable for wheel rims with different hole arrangements.
The invention is based on the object of developing a clamping device of the pertinent type which can be used for different hole arrangements and in which the risk of centering errors is reduced.
According to the invention, this object is attained with the characteristics disclosed in the characterizing portion of Claim 1.
The basic idea of the invention consists of counteracting the possible radial inaccuracies in the radial position of the centering cones on the ends of the centering bolts by centering the ends during the clamping process due to their engagement into an annular groove in the locating flange, and thusly inaccuracies in the position of the centering bolts are corrected. The annular groove is simultaneously able to exactly center centering bolts of different hole arrangements that, however, have the same radial position.
According to one practical additional development of the invention, the centering bolts can be conventionally inserted into bores in the clamping flange. In this application of the known principle, the advantage of the invention can be seen in the fact that the tolerances in the plug-type connection can be significantly higher without causing centering errors.