Measuring and testing – Rotor unbalance – Dynamic
Reexamination Certificate
1999-01-05
2001-06-26
Kwok, Helen (Department: 2856)
Measuring and testing
Rotor unbalance
Dynamic
C409S131000
Reexamination Certificate
active
06250155
ABSTRACT:
TECHNICAL FIELD
The invention relates to a method for the balancing of rotors and more particularly of tool holders of machining devices, in the case of which the size and direction of an imbalance of the rotor is ascertained in a computer of a balancing machine and balancing is performed by spreading apart at least two balancing elements with a predetermined degree of imbalance by movement into corresponding positions of adjustment.
Furthermore the invention relates to a device for the performance of the method comprising computer operated balancing machine, in which the size and direction of an imbalance of the rotor is ascertained, and comprising at least two balancing elements, by which the imbalance of the rotor is compensated for by spreading apart into corresponding positions of adjustment.
BACKGROUND OF THE INVENTION
Problems in connection with rotor imbalance in machining device such as machine tools are being made more serious by the use of ever increasing speeds of such machining tools, as for example in the case of high speed cutting (HSC). Attempts are frequently made to compensate for undesired imbalance of rotors, which leads to vibrations. One of the known methods produces imbalance compensation with the aid of imbalance correcting rings as disclosed in the patent publication WO 90/11 862.
In the method and apparatus in accordance with this publication WO 90/11 862 two balancing rings are employed in order to correct a lack of balance of a tool holder and tool. The balancing rings are so spread out in their angular position in relation to the tool holder that the imbalance produced by same is equal and opposite to the imbalance of the tool bolder together with the tool. In order to set the spread of the balancing rings scales are provided on the balancing ring, which extend for example from zero to 359° (complete circle) or only from 90 to 180°. The setting of the balancing rings by with the aid of such scales is complicated and leads to misunderstandings during setting the angle of spread. As a rule poorly phrased directions for use and tables are provided, which combine both the spread and also the imbalance to be set on the balancing rings. This means that only persons trained in balancing techniques are able to make use of such directions for use and tables, something also requiring much time. Furthermore such directions for use and tables frequently only relate to certain specific tool holders with tools of the same manufacturer so that this system is inflexible and not sufficiently accurate.
OBJECT OF THE INVENTION
One object of the invention is to provide a method and an apparatus for balancing rotors, and more particularly tool holders of machine (or chip cutting) tools with the purpose of allowing simple, universal and accurate setting of positions of balancing elements without special knowledge of balancing technology.
SUMMARY OF THE INVENTION
For this purpose the method of the invention is characterized in that the positions of adjustment of the balancing elements is determined from the measured imbalance of the rotor and the size of the balancing elements, that the rotor is turned in the balancing machine until a balance position is reached in which the position of adjustment of the one balancing element is at a predetermined position in relation to balancing machine, that a visible marking is projected onto the balancing element, when the rotor is in the balance position, that the balancing element is set in its position of adjustment by bringing a mark provided on the balancing element into alignment with the visible marking and that the last three steps mentioned are repeated for the other balancing element.
For setting the spread of the balancing elements, that is to say for turning the balancing elements into the positions of adjustment, it is thus no longer necessary to have recourse to tables or directions for use. In fact, the visible marking, which is turned on in the balance position of the rotor and is turned off again, when the balance position is left, indicates the point, into which the balancing element must be turned until a mark provided on the balancing element is aligned with the visible marking and accordingly the position of adjustment of the balancing element is reached.
As pairs of balancing elements are utilized having different degrees of imbalance, the degree of imbalance of the respectively employed pair of balancing elements is supplied to the computer. From such data and the imbalance of the rotor the position is then calculated at which the marks of the balancing elements must be set in order to correct the imbalance of the rotor. The marks may for this purpose be arranged at any desired point on the periphery of the balancing elements providing that their position in relation to the maximum imbalance of the balancing element is set in the computer.
Furthermore it is an advantage for the rotation of the rotor into the positions of adjustment to be performed automatically under the control of the computer. Since the information concerning the positions of adjustment is set in the computer, no extra effort will be required in performing the rotation of the rotor and manipulation of the rotor by hand is avoided. Also a failure to find the position of adjustment is avoided because of the rotor being rotated so fast that the turning on of the marking is not able to be discerned.
Furthermore it is an advantage for the visible marking to be produced by a laser, which is controlled by the computer, it being an advantage in this respect for the visible marking to be a line, aligned with the rotor axis, projected onto the rotor. This ensures that the visible marking impinges on the balancing rings even if the same are arranged at different points on the rotor, as for example at different levels above the adapter of the balancing machine. In order to ensure that the visible marking is not overlooked on turning the balancing elements by hand, it is an advantage if the visible marking is caused to flash in a predetermined angular range preceding and following the balance position and in the balance position is presented continuously.
Using the method of the invention it is possible to perform both static balancing in one balancing plane and also dynamic balancing in two balancy planes. For the latter case the steps, which were performed for balancing in the first balancy plane, are repeated for the second balancy plane.
In order to ensure that there are no misunderstandings as to which marking relates to which set of balancy elements when balancing is performed in two planes (dynamically), it is an advantage for the markings for the two balancing planes to be arranged mutually angularly offset, preferably by 60°. In order to provide a further distinction between the two markings it is possible for the markings for the two balancing planes to be in different colors. This ensures that the two sets of balancing elements may be reset to the correct positions of adjustment in the two balancing planes.
The apparatus for performing the method is characterized by a marking device, which under the control of the computer projects visible markings on the balancing elements, when the rotor is located in its balanced~position at which the positions of adjustment of the balancing elements are in a predetermined position in relation to the balancing machine.
For (dynamic) balancing in two planes it is an advantage to provide one marking device for each balancing plane.
It is an advantage for the balancing elements to be balancing rings, which have a first mark at the point of imbalance. Although as a reference point for the adjustment of the balancing ring it is also possible to use a grub screw, with which the balancing ring may be set in its position, a mark, preferably a marking line, is preferred, because it may then be more accurately performed.
In accordance with an advantageous form of the device the balancing rings possess a second mark, which is offset through 180° in relation to the first mark. This means that the two balancing rings m
Harborth Andreas
Hormann Dionys
Hofmann Mess und Auswuchttechnik GmbH & Co.
Kwok Helen
Reed Smith Hazel & Thomas LLP
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