Measuring and testing – Rotor unbalance – Dynamic
Reexamination Certificate
2002-07-03
2003-07-22
Kwok, Helen (Department: 2856)
Measuring and testing
Rotor unbalance
Dynamic
C073S001140
Reexamination Certificate
active
06595052
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to the precise correction of imbalance of rotating work pieces and more particularly to new and improved self-calibrating work piece balancing machines having the capability to automatically determine and correct the imbalance of rotating parts and to automatically self-calibrate under predetermined operating conditions and further to new and improved processes for the automatic calibration of work piece balancing machines.
2. Description of the Prior Art
Production equipment such as automatic work piece balancing machines for rotating metallic work pieces at high rotational speeds and effecting the dynamic balancing thereof by adding balancing weights in appropriate locations thereon or by removal of mass therefrom have been successfully employed for many years. Highly developed machines in this category have balance computers that calculate the amount of weight adjustment needed for dynamically balancing different work pieces and control the balancing speeds and many other machine operations. More particularly these balance computers function with the machine hardware to precisely locate the positions in selected balancing planes on the work piece where weight correction is needed for work piece balancing and for activating the tools to accomplish the actual weight correction. These precisioned operations are required for an effective single balancing operation or for the repeated rotational balancing of a quantity of unbalanced work pieces in mass production operations.
For such work, the balancing machines need to be precisely calibrated so that the exact location on each individual work piece for weight-adjustment can be quickly and precisely determined and the appropriate balance weight adjustment quickly made. Prior to the present invention, work piece balancing machines required a time consuming and tedious manual process of stopping and starting the rotating machine to manually add and remove calibration weights to a master or selected standard work piece for calibrating the machine. Such prior calibrating procedures were prone to various human errors and required great skill and care to avoid calibration mistakes. Personal care also had to be taken by the operator since it was generally necessary to physically handle, add, and remove calibration weights with respect to the standard or master and the starting and stopping of the machine for the calibration thereof.
SUMMARY OF THE INVENTION
In contrast to the prior machines and calibration processes, the new and improved self-calibrating work piece balancing equipment and processes of this invention reduces machine down-time for calibration and to a large extent eliminates the labor and skill including attention to precise detail previously required of the operator to manually calibrate a balancing machine. This advancement is achieved in this invention by the unique incorporation of one or more automatic load or force injecting units, hereinafter referenced as unbalance injector devices, into a new and improved dynamic balancing machine featuring automatic self calibration. These on-board devices provide hands-free selection and changing of calibration loads and along with other machine equipment cooperate to form and complete a new and improved self-calibrating work piece balancing machine. These unbalance injection devices are uniquely operative in this invention in that known unbalancing loads are automatically injected into the rotating chucks or other workpiece mountings of the machine to establish inertia axes offset from the rotational axis of a standard or master work piece rotatably driven therein. Known moments are resultantly established at predetermined correction planes that extend through the work piece whose values are fed to a balance computer of the machine for the automatic calibration thereof. Such calibration can be readily and quickly accomplished with minimal operator input and in many cases, while the master is being continuously rotatably driven. Moreover, these unbalance injector devices are generally arranged into the machine construction so that they are offset to one or both ends or extremities of a calibrating master or known standard workpiece operatively mounted for rotation in the machine. The physical characteristics of the calibrating work piece are not changed such as in prior calibration procedures and the calibrating workpieces are not physically handled or touched by the calibrating operator except for machine loading and unloading.
For single plane calibration, base line imbalance measurements are taken from the rotating master or known standard and fed to a balance computer incorporated into the balancing machine where the data is registered. The unbalance injection device is then automatically activated to inject known imbalance loads into a base injection plane of the machine. This plane may transversely extend through the unbalance injector device and the spindle or other machine component securing the calibrating work piece and operatively mounting the injector device for rotation of these components about a spin axis. This injected force is, in effect, linearly translated as an unbalancing load to the master in a predetermined correction or calibration plane parallel to the base plane and transverse of the work piece spin axis. The cradle supporting the work piece mounting and spinning equipment is usually mounted by suspension spring construction and is subject to vibratory excitation from the rotational imbalance of the master or standard during machine calibration, as well as from unbalanced workpieces subsequently balanced by the machine.
Vibratory and positional signals reflecting these known imbalance loads and the location of the eccentricity as applied to the standard or master by the unbalance injector device are received by synchronizer and vibration pick up units. Data from these pick-ups are fed to the balance computer in a first calibration thereof. The machine is stopped and the part rotated relative to the work piece holding chuck or other securement a predetermined number of degrees, 180 degrees for example. Known imbalance loads from the imbalance injection device are again injected into the machine and translated to the standard or masterwork piece in the correction plane and the final calibration readings are taken. With known calibration imbalance loads applied in specific locations in known correction planes, the balance computer will identify and store the known imbalance data and calibrate with reference thereto.
With such calibration, the computer will subsequently recognize imbalance loads and eccentricities in unbalanced work pieces being processed with the machine and effect the accurate weight correction and location to effect the dynamic balancing of such work pieces.
For double plane calibration at least two unbalance injecting devices and associated controller are integrated the balancing machine and the balance computer thereof so that known unbalancing loads injected into a rotating portion of the machine are translated from the injection planes through the machine into calibration planes through a calibrating master or known standard workpiece operatively mounted in the machine. These calibrating planes are spaced apart from one another and the unbalancing loads cause the inertia axis of the master or standard to misalign with respect to the spin axis thereof. The magnitude of the resulting dynamic unbalance is used to calculate the moment or couple generated at a predetermined spin rpm. The injected unbalances generate vibrations, which are picked up by spaced pick up devices and generate data supplied to the balance computer to effect the calibration thereof.
This new and improved self-calibrating machine can be easily calibrated by different machine operators of varying skills including those that are mechanically oriented and can follow prescribed procedures but have little calibration experience. The machine may be conditioned for the automatic cali
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