Test rotor for balancing machine

Details Test rotor for balancing machine Test rotor for balancing machine

1999-11-19

2001-10-23

Chapman, John E. (Department: 2856)

Measuring and testing

Instrument proving or calibrating

Dynamometer

C073S487000

Reexamination Certificate

active

06305211

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a test rotor for balancing machines having a plurality of receptacles for test weights in which fitting surfaces are provided becide the receptacles against which fitting surfaces of the test weights are placed.
Balancing machines, particularly universal balancing machines, are checked for precision with test rotors. Such tests are carried out when the machine is initially accepted by the customer or else later as the need arises. With test rotors, for example, the smallest achievable residual unbalance or the unbalance reduction ratio is tested, whereby the test means, i.e. the test rotor and the test weights, as well as the process sequences are all specified in greater detail in International Standard ISO 2953, incorporated herein by reference. Normally, the test weights or test masses are screw fitted along the circumference of the rotor, and their centers of gravity and masses must be precisely known. ISO 2953, Section 10.2.3, provides information about the necessary precision in the three directions, namely, for the distance of the compensation planes in which the test weights must be arranged, for the compensation radii and for the angle positions of the test weights. An unbalance reduction ratio of 95% translates into a tolerance of 0.5%. Thus, for example, the angle position of the test weights has to be accurate to within 0.29°. For this purpose, in a known manner, the test weights are provided with a fitting collar that is associated with a fitting borehole section at the far end of the screw-in borehole on the rotor. When the test weights are screwed in, the fitting surfaces can seize and the threads can be stripped, which then damages the rotor and frequently renders it unusable.
SUMMARY OF THE INVENTION
The present invention is based on the objective of creating a test rotor of the type mentioned above but which is characterized by the simple, precise and secure manner in which the weights are positioned.
The overall objective is achieved, according to the present invention, in that the fitting surfaces for the angle positioning are level surfaces that run in the lengthwise direction of the rotor.
With the invention, it was found for the first time that the placement of the test weights on level fitting surfaces of the rotor in the radial and circumferential directions of the rotor ensures the required positioning precision. It turned out that a fitting surface positioning in the third direction, however, is superfluous. Level, angular-accurate fitting surfaces can be produced more simply and less expensively than fitting boreholes that must be drilled with angular accuracy. This is especially the case when a level fitting surface which has been made in one single operation, for example, by means of milling, is associated with a several receptacles or screw-in boreholes and extends preferably over the entire axial length of the rotor section provided for receiving the test weights. In many cases, the required positioning precision is achieved with the placement of the test weight on just one level fitting surface, which results in further simplification and cost reduction.
Another embodiment of the invention provides that two fitting surfaces that run parallel to each other are provided on both sides, equidistant from the receptacle. Here, it is not necessary to control the placement onto the fitting surface, which is only required with one level fitting surface since, when fitting surfaces are arranged on both sides, the associated surfaces are also automatically placed on both sides. A simple production is ensured if the fitting surfaces are formed by the side surfaces of a longitudinal slot.
An especially advantageous embodiment is one in which the longitudinal slot is stepped and the side surfaces have different distances pairwise since, in this manner, test weights with different fitting collars can be precisely positioned. The diameter of the fitting collar or the width of the slot can also be associated with test weights having different masses.


REFERENCES:
patent: 4716761 (1988-01-01), Ito et al.

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