DE1573644B2 - Method and device for balancing - Google Patents

Description

60

The invention relates to a method and a device for balancing rotors by multiple Measurement runs in which the unbalance according to size and angular position and interim compensation the measured unbalance is measured. In particular, the invention is suitable for balancing machines for the automatic measurement and compensation of an imbalance.

In the case of successive measuring processes with intermediate compensation, the problem arises that the remaining unbalance after the compensation is in the same or almost the same place can lie like the unbalance measured before the compensation, which is eliminated by the compensation should. In order to compensate for the residual imbalance, the material would have to be the same or almost the same Can be removed from the point where material has already been removed. It is common not possible because this would damage the body to be balanced. When the material acceptance through. Drilling takes place and the amount of material accepted is determined by the drilling depth of the drill then it can happen that the drill plunges into an existing hole or into such a hole Would have to cut the borehole. This would of course mean that the amount of material removed would become uncontrollable Way depending on the drilling depth. It can also damage the tool and Enter workpiece.

The problems outlined arise above all in automatic balancing machines. A balancing machine does not "know" whether the drill is going into a previously drilled hole or the drilling depth corresponds to an actually removed amount of material. This is one of the Reasons why the balancing accuracy of automatic balancing machines is lower than that of manual balancing. In the case of automatically working balancing machines, one is generally up limited a single measurement and compensation process. If you want to balance more precisely, you have to usually a manual balancing process to remove the residual imbalance.

The invention is based on the object of avoiding the difficulties outlined.

In a method of the type mentioned at the outset, this is done according to the invention in that at every compensation the imbalance is always compensated at a point which is opposite to the measured one Angular position is slightly offset in a single predetermined direction.

The invention takes advantage of the fact that one of the size is essentially correct Compensation for the imbalance, which is, however, afflicted with a small angular error, is then obtained Remaining unbalance offset by an angle of approximately 90 ° compared to the previous unbalance is.

If, therefore, according to the invention, every time one arbitrarily finds a small angle error in provides a predetermined and always the same direction, then the imbalance moves in the successive Measurements in jumps of approximately 90 ° around the circumference of the balancing body, see above that one can provide up to four equalization processes and yet the equalization always takes place in different places of the scope.

It is evident that the residual imbalances obtained will usually be considerably smaller than the originally existing unbalance, so that the measured unbalances converge to zero.

A method for balancing watch balances is known in which the material is removed the balance tires are certainly carried out at different points when compensating for the unbalance (German Auslegeschrift 1052 914, patent specification

40041 of the Office for Inventions and Patents in East Berlin). This is a static balancing by allowing the balance wheel to settle in their center of gravity and the attachment of fixed additional imbalances of the same size. It doesn't happen there either a measurement of the unbalance size nor a compensation of a measured unbalance.

As said, the invention can be used with particular advantage in automatically operating balancing machines. The invention therefore also relates to a balancing machine for automatically measuring and compensating for an unbalance with a measuring device for the unbalance according to size and angular position, a size memory for the measured unbalance size, a compensation device which can be controlled by the size memory, an angle memory for the angular position of the unbalance, screwing means for screwing the balancing body into a position determined by the angular memory relative to the compensating device ¹ and a program by which the measuring, screwing and compensating process can be controlled in succession, and consists in turning the balancing body through the screwing means is brought into such a position relative to the compensating device that the compensation takes place at a point slightly offset from the position of the measured unbalance in a predetermined direction, and that several successive measuring and compensating processes can be controlled by the program.

It is particularly advantageous if the balancing machine has an automatic measuring range switchover which automatically switches to the next more sensitive measuring range during the measurement causes the measured value to be a specified percentage of the respective activated measuring range not reached.

It can then be used in the various successive balancing processes with increasingly sensitive ones Measuring ranges are worked to the same extent as the originally existing unbalance is already partially balanced. One can do this with one for automatic balancing machines balance unusual accuracy.

The arrangement will advantageously be made in such a way that the program unit does not have any further measuring and Compensating process controls if at the forward. previous measuring process in the most sensitive measuring range was worked. If already during a measuring and compensation process in the most sensitive measuring range has been worked, then it would be pointless to have further measurement or compensation processes follow. Because with the size after exactly correct compensation of the measured unbalance and a smaller one Angular error the position of the unbalance by approximately 90 ° jumps, it is advisable if the program control unit has a maximum of four measurement and compensation processes taxed.

An embodiment of the invention is described below with reference to the figures.

F i g. 1 illustrates the change in the angular position the imbalance in the case of a compensation of the measured imbalance provided with an angular error;

F i g. Figure 2 shows schematically an automatic balancing machine according to the invention.

In Fig. 1, the vector U denotes an imbalance measured during a measurement process. It will be here and below. for the sake of simplicity it is assumed that a purely static unbalance is being compensated, or only the unbalance is considered in a compensation plane. It is known that any unbalance of a rotor can be represented by two such vectors in two planes (compensation planes) and measured as such, and the described method can be used individually for each of these planes. In the compensation process following the measurement, the size of the. The unbalance is essentially balanced out exactly. However, let there be a certain angular error φ between the theoretically required compensation, which is represented by the dashed vector T , and the compensation actually taking place, represented by the vector A. In Fig. 1 this is shown somewhat exaggerated. It can be seen that there is a resulting residual unbalance, which is represented by the vector R , which encloses an angle with the unbalance U originally present. It is :

180 ° - »

The table below shows the angle changes ψ and the residual imbalances R (in percent of 17) for various error angles φ . You can see that for φ -> 0 the angle change is ψ_ ^ 90 °.

V ₀ R in ° / o of U 0 90 0 0.5 89.75 0.87 1 89.5 1.75 2 89 3.49 3 88.5 5.22 4th 88 7.0. 5 87.5 8.7 6th 87 10.5 7th 86.5 12.2 8th 86 13.9 9 85.5 15.65 10 85 17.4 15th 82.5 26.1 20th 80 34.7 25th 77.5 43.3 30th 75 51.8 35 72.5 60.1 40 70 68.4 45 67.5 76.5 50 65 84.5 55 62.5 92.4 60 60 100.0

If the equalization is not complete even in terms of size, then

A <U,

the angle ψ ' by which the unbalance "jumps" would be smaller than the angle ψ given above. It is now evident that an imbalance cannot be ideally compensated for practically immediately, and this applies in particular to automatically operating balancing machines. This is due to the fact that with a relatively large initial imbalance (»Ur-

imbalance «) must first work with a correspondingly large measuring range. Both the sizes and the angle measurement will be afflicted with a certain error, and in practice the compensation will also have size and angle errors with respect to the measured errors. For precise balancing, it is therefore necessary, after the first compensation, to check the unbalance by means of a further measuring run and to determine and compensate the remaining unbalance with a more sensitive measuring range. However, it cannot be ruled out that the residual unbalance R lies at the same point as the original unbalance U, for example if the compensation actually takes place without angular errors, but not sufficiently in terms of size. The imbalance can also jump by approximately 90 ° in one direction during a first compensation process and jump back again by approximately 90 ° during a second compensation process. The difficulties outlined above then arise. The invention therefore provides that through an arbitrarily introduced angle error, "jumping" always takes place in a desired predetermined direction, so that one can be sure of always being able to compensate for the imbalances at different points on the balancing body in several successive balancing processes. This arbitrary angular error must of course be slightly larger than the spread that is to be expected when measuring the position and when turning the balancing body into its processing position.

F i g. 2 shows an automatic balancing machine operating according to the method according to the invention, d. H. a balancing machine in which the unbalance is measured according to size and position and then is automatically balanced.

The unbalance measurement

A balancing body 10 is driven by a drive motor 12 via a gear 14, 16, 18. The unbalance forces or vibrations are converted by a transmitter 20 in a known manner according to size and phase position into a corresponding electrical signal, which is amplified in a measuring amplifier 22 and fed to two phase-sensitive rectifiers 24 and 26 connected in series or in parallel. An auxiliary voltage generator 28 rotates with the unbalanced body 10, the rotor of which is excited with a direct voltage U _{via a switch S 12} and which phase shifts two of them by 90 ° against each other via an adjustable phase shifter 30. delivers alternating voltages that are pushed and synchronized with the balancing body rotation. These are fed in a known manner as control voltages to the two phase-sensitive controlled rectifiers 24 and 26, so that two DC voltages arise at their outputs 32 and 34. These DC voltages correspond to the components of the imbalance in relation to two mutually perpendicular planes which are determined by the phase position of the auxiliary voltages or the position of the rotor of the phase shifter 30. The DC voltage at the output 34 is fed to a servomotor 38 during the first unbalance measurement process via an amplifier 36 and a switch contact S ₁₁ (the function of which will be explained later), which drives the rotor of the phase shifter 30 depending on the polarity of the DC voltage according to one or the other adjusted in the other direction. The "reference planes" are twisted in such a way that one component of the imbalance becomes zero. The other DC voltage at the output 32 then corresponds to the absolute size of the unbalance, while the position of the phase shifter 30 provides a measure of the angular position of the unbalance.

The measured value at the output 32 of the rectifier 24 is sent once to a range switch 40 fed. This range switch causes the measuring amplifier 22 to switch to the respective , next sensitive measuring range, provided the output DC voltage a predetermined percentage, e.g. B. 20% of the full scale value not reached. This ensures that the machine always works in the most favorable measuring range.

The measuring range switch 40 sends a signal to a control device via a further output 42 44, the function of which will be described later. The one that results after switching the measuring range A signal at output 32, which corresponds to the size of the unbalance, is fed to a memory 46 and also - for checking purposes - displayed on an instrument 48. It is therefore after the adjustment has been carried out of the phase shifter 30, the size of the unbalance in the memory 46 and the position of the unbalance in the Phase shifter 30 stored.

The balancing process

The compensation process is automatically initiated by the control device 44 after the end of the measurement process. For this purpose, the balancing body is first screwed into such a position that the measured unbalance comes to rest under a processing machine (not shown), such as a drill. For this purpose, instead of the direct voltage U =, an alternating voltage Uta is applied to the rotor of the generator 28 via the switch contact S _12. This alternating voltage induces alternating voltages in the stator windings of the generator 28 and causes corresponding currents in the stator windings of the phase shifter 30, which are connected in a known manner to the stator windings of the generator. As a result, alternating output voltages are generated in the two crossed rotor windings of the phase shifter 30 ″ as if the generator were rotating during measurement operation. The two alternating output voltages behave like sine to cosine of the angle α between the rotors of generator 28 and phase shifter 30. The alternating voltage t / «I is also applied _{to the input of the phase-sensitive rectifier 24 and 26 via the switch contact S 13.} At the output of the rectifier, voltages proportional to cos« and sin α are obtained S _{11 is} now placed on a motor 50, which rotates the balancing body via a gear 52, 54 and the gear 14, 16, 18. This changes the position of the generator rotor and thus the angle α. The amplitude of the cos α voltage on the phase shifter rotor is changed. The balancing body 10 is in a defined position relative to the phase shifter rotor 30 rotated, namely so that cos α = 0 is α = 90 °. The arrangement can of course easily be chosen so that in this position the measured unbalance is below the processing machine. After the balancing body has been screwed in, the control unit

44 ζ. B. switched on a drill whose drilling depth is determined by the memory 46. That is in itself known and not shown here.

In order to be able to control an angle error in the compensation for the reasons described, a resistor 56 is located in the circle of the cos α voltage, to which a relatively small error voltage is fed from a voltage source 58 via a switch S _2. This has the same frequency and phase as the voltage 17 and causes the balancing body 10 to be rotated to an angle slightly different from 90 ° relative to the phase shifter rotor.

The imbalance is not compensated exactly at the measured angle. As a result, the residual imbalance jumps in one direction according to the principles explained in FIG. 1. There remains a residual imbalance R , which, however, is usually in a more sensitive measuring range than the original imbalance. After the end of the equalization process, the control device 44 initiates a new measurement process and equalization. The measuring range switch 40 will generally switch to a more sensitive measuring range, and the balancing body 10 will be rotated into a position for compensation which is rotated about 90 ° with respect to the position in the previous compensation. During the next measuring and balancing process, the unbalance jumps again in the same direction, etc. Up to four measuring and balancing processes can be started automatically without the balancing having to take place twice at the same point or at almost the same point. After the third balancing process or when work is already in progress in the most sensitive measuring range, the control unit 44 opens the contact S ₂ , so that the next balancing takes place without angular errors and the balancing process is then ended. The measuring range in which work is being carried out is reported to the control device 44, as described, via the output line 42 of the measuring range switch 42.

It is clear that the angular error φ can also be entered during the measurement by balancing the adjustment using the A-C phase shifter combination on the measuring amplifier or an auxiliary voltage circuit by phase shifting the measurement voltage U _7n or the auxiliary voltage U _h · cos ω t so disturbs that the determined imbalance does not enter exactly under the compensation tool, but shifted by the angle φ with respect to the compensation tool, whereupon the compensation is inevitably carried out shifted by φ. This jR-C phase shifter device in the measuring amplifier or in the auxiliary voltage branch can preferably be switched off so that the angle error φ is no longer entered in the last measuring and compensation process.

It is of course also possible (preferably in the case of small balancing machines, in which the associated balancing machine tool is also small), the balancing tool or the entire machine tool with the first rotor, in order to adjust the intended angular error φ and get back to the point in the last balancing process, in which the unbalance sits, start, with z. B. for angle error = φ and angle error = 0 on the tool or machine swivel device, two limiting stops are attached.

1 sheet of drawings 409 507/15

Claims (6)

Patent claims: 1. Procedure for balancing rotors by repeated measurement runs in which the unbalance is measured according to size and angular position, and intermediate compensation of the measured Imbalance, characterized in that each time the imbalance is compensated, it is always compensated at one point, which is slightly offset from the measured angular position in a single predetermined direction is. 2. Balancing machine for the automatic measurement and compensation of an imbalance according to the Method according to claim 1 with a measuring device for the unbalance according to size and angular position, a size memory for the measured unbalance size, a compensation device, which can be controlled by the size memory, an angular memory for the angular position of the unbalance, Screwing means for screwing the balancing body into one determined by the angular memory Position relative to the compensating device and a program by which the measuring, screwing and compensating process can be controlled one after the other, characterized in that that the turning of the balancing body by the screwing means in such a position to the compensation device the effect is that the compensation is somewhat related to the position of the measured unbalance in a predetermined direction offset position takes place, and that the program work several successive measuring and compensation processes can be controlled. 3. Balancing machine according to claim 2, characterized in that it is an automatic Measuring range switchover, which automatically switches over to the next more sensitive measuring range, provided that the measured value has a specified percentage of the activated measuring range not reached. 4. balancing machine according to claim 3, characterized in that the program mechanism does not control any further measurement and compensation processes if in the previous measurement process was worked in the most sensitive measuring range. 5. balancing machine according to one of claims 1 to 4, characterized in that the Program switching mechanism controls a maximum of four measurement and compensation processes. 6. balancing machine according to claim 4 or 5, characterized in that the last balancing process the equalization is effected without displacement.