KR100355760B1 - Method and apparatus for controlling state of ball bearing using exciter - Google Patents

Abstract

The present invention relates to a spindle bearing state control technique using an electromagnetic exciter capable of compensating and controlling the spindle stiffness according to the driving load of the spindle in real time using an electromagnetic contactless exciter. It uses an electromagnetic exciter to have a rotating shaft, detects vibration during rotation through a vibration sensor, and analyzes the frequency response appearing in the detected vibration signal to detect the bearing's state such as a change in bearing stiffness and preload, By controlling the driving of the exciter based on this detection result, the rotational degree and rigidity of the spindle can be optimally controlled, thereby increasing the stability of the intelligent spindle system and realizing high-speed, high-precision performance.

Description

Method and apparatus for controlling spindle bearing state using electromagnetic excitation {METHOD AND APPARATUS FOR CONTROLLING STATE OF BALL BEARING USING EXCITER}

The present invention relates to a technique for controlling a state of a spindle bearing, and more particularly, to a method and apparatus for controlling a state of a spindle bearing using an electromagnetic exciter suitable for monitoring and compensating control of a state of the spindle bearing using an electromagnetic exciter. .

As is well known, high speed spindle systems supported by ball bearings, which are most widely used in production, are subject to thermal deformation due to heat generation of bearings and motors during operation, which is characterized by a large number of static stiffness and dynamic characteristics of the spindle. Cause change. In particular, the change in the calorific value, the cooling condition and the change in the ambient temperature according to the change of the operating load condition act as a major factor to change the stiffness of the spindle, causing many problems such as the stability of the spindle rotation and the degree of machining.

Therefore, in order to solve the above problems, it is very necessary to monitor the bearing state inside the main spindle used during operation in real time to compensate and control the bearing to the optimum state, but these techniques are not known at present.

The present invention has been made in view of the above points, and provides a spindle bearing state control method and apparatus using an electromagnetic exciter capable of compensating and controlling the spindle stiffness according to the driving load of the spindle in real time using an electromagnetic contactless exciter. Its purpose is to.

In accordance with an aspect of the present invention, there is provided a method for monitoring and compensating a bearing state of a spindle system having a rotating shaft surrounded by a housing with a ball bearing interposed therebetween. Calculating and storing an initial stiffness coefficient and a damping coefficient of the main axis in the state of being made; Detecting a vibration generated during operation of the spindle system and detecting a frequency change generated when the rotary shaft is rotated; Obtaining a frequency response function based on the detected vibration signal and the detected frequency change; Calculating a stiffness coefficient during operation and a damping coefficient during operation of the main shaft by analyzing the obtained frequency response function; And comparing the initial stiffness coefficient and the damping coefficient with the calculated stiffness coefficient during operation and the damping coefficient during operation to detect an amount of change, and having an electromagnetic exciter mounted on a predetermined portion of the housing based on the detected amount of change. The present invention provides a spindle bearing state control method using an electromagnetic exciting device, which is configured to compensate for a stiffness change of the spindle.

According to another aspect of the present invention, there is provided an apparatus for monitoring and compensating a bearing state of a spindle system having a rotating shaft surrounded by a housing with a ball bearing interposed therebetween, corresponding to a shock wave signal provided from the outside. An electromagnetic exciter which excites the main shaft by an excitation force and generates a frequency change signal of the main axis generated during operation; A vibration sensor mounted on a predetermined portion of the housing to detect vibration generated in the spindle system; A signal processor obtaining a frequency response function based on the detected vibration signal and the detected frequency change signal; The obtained frequency response function is analyzed by a numerical analysis algorithm to calculate the stiffness coefficient during operation and the damping coefficient during operation of the main shaft, and the preset stored initial stiffness coefficient and the damping coefficient and the calculated stiffness coefficient during operation and the damping during operation. An analysis / compensation controller for comparing the coefficients to detect the change amount and generating an exciter drive control signal corresponding to the detected change amount; And an electromagnetic exciter configured to generate a shock wave signal for driving the exciter in response to the exciter drive control signal provided from the analysis / compensation controller and to drive the electromagnetic exciter with the generated shock wave signal. Provides a bearing state control device.

1 is a conceptual block diagram of a spindle bearing state control apparatus using an electromagnetic exciter according to a preferred embodiment of the present invention;

FIG. 2 is a cross-sectional view of an electromagnetic exciting device showing an example of the electromagnetic exciting device shown in FIG. 1; FIG.

3 is a block diagram of an example of the exciter driver shown in FIG.

<Description of the code | symbol about the principal part of drawing>

102 housing 104 rotation axis

106: Ball Bearing 108: Electromagnetic Exciter

110: vibration sensor 120: signal processor

130: analysis / compensation controller 140: exciter driver

302, 304: input selection block 306: channel selection block

308: voltage control block 310: triangle wave generation block

312: comparison block 314: amplification block

The above and other objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings by those skilled in the art.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the core technical gist of the present invention is to have a rotating shaft using an electromagnetic type of exciter in an intelligent spindle, to sense vibration during rotation through a vibration sensor, and to analyze the frequency response appearing in the detected vibration signal of the bearing. By detecting the state of the bearing such as the change in the rigidity and the preload, and controlling the drive of the exciter based on the detection result, to control the rotational degree and rigidity of the main shaft to the optimal state, the object of the present invention through this technical means It can be easily achieved.

1 is a conceptual block diagram of a spindle bearing state control apparatus using an electromagnetic exciter according to a preferred embodiment of the present invention. The spindle bearing state control apparatus includes an electromagnetic exciter 108, a vibration sensor 110, and a signal processor 120. , An analysis / compensation controller 130 and an exciter driver 140.

Referring to FIG. 1, an electromagnetic exciter 108 is mounted inside the housing 102 and has a rotating shaft 104 with a desired force (ie, with shock waves) in a non-contact manner without damaging the rotating shaft 104. By applying a static force to the rotating shaft 104 in accordance with the driving force (PWM pulse) provided from the exciter driver 140 to be described later, the ball bearing 106 located between the housing 102 and the rotating shaft 104 It functions to increase or decrease the stiffness, and transmits an excitation frequency change signal generated by driving the exciter driver 140 to the signal processor 120. Here, shock wave excitation means excitation of all frequencies.

That is, the stiffness of the main shaft is reduced due to the thermal deformation during operation, the stiffness is reduced, so in this case it is necessary to increase the stiffness of the main shaft, for this purpose by exciting the electromagnetic exciter (108) to rotate the rotating shaft ( Pulling 104 causes a radial force to act on the ball bearing 106, and as a result, the preload of the ball bearing 106 increases, thereby increasing the rigidity of the ball bearing 106. The damping function adjustment of the main shaft is also performed like the stiffness control, and in practice, the stiffness control and the damping function adjustment are simultaneously performed.

At this time, the axial monitoring and radial monitoring of the main shaft can be performed using the electromagnetic exciter 108, the axial monitoring using the electromagnetic exciter 108 in the axial direction by vibrating the vibration sensor 110 Means to obtain a vibration signal through, the radial monitoring means to obtain a vibration signal through the vibration sensor 110 by the excitation in the radial direction using the electromagnetic exciter (108). The present invention corresponds to the radial monitoring method since the electromagnetic exciter 108 has a radial excitation.

As the electromagnetic exciter 108 performing the function as described above, for example, an electromagnetic exciter having a shape as shown in FIG. 2 can be used.

Referring to FIG. 2, the electromagnetic exciter 108 applies a current to a coil 1085 wound around each pole 1083 / a-1083 / h of the stator 1081, and each pole 1083 of the stator 1081. / a-1083 / h) are electromagnets with N and S poles, respectively, which operate on the principle of generating electromagnetic force and applying force to the axis of rotation of the spindle system.

Where each pole pair consists of two opposite poles (e.g., 1083 / a-1083 / e, 1083 / b-1083 / f, 1083 / c-1083 / g, 1083 / d-1083 / h) Each function as one channel. When the driver selects and excites the pole pairs facing up and down, the excitation force is applied in the up and down direction of the main axis. When all the pole pairs are selected and excited, the excitation force is applied to the whole axis. Works.

On the other hand, the vibration sensor 110 is mounted on an outer predetermined portion of the housing 102 (for example, the portion adjacent to the ball bearing 106) to detect the vibration generated when the intelligent spindle rotates, that is, the bearing By detecting the vibration signal of the excited rotating body 104 is transmitted from the inner ring to the outer ring through the ball to the housing 102, the vibration signal detected here is transmitted to the signal processor 120.

Next, the signal processor 120 includes, for example, a digital signal processor, and inputs an excitation input (vibration frequency change) provided from the electromagnetic exciter 108 and a vibration signal provided from the vibration sensor 110. The frequency response function is calculated accordingly. For example, assuming that the spindle system is a single degree of freedom, the frequency response function H (ω) in the spindle system can be calculated as shown below.

In Equation 1, F denotes a force, X denotes a displacement, M denotes a mass, C denotes a damping coefficient, and K denotes a stiffness coefficient.

At this time, in the present invention, since the shock wave excitation having all frequency bands is performed, the response characteristic for each frequency at the time of excitation can be obtained. Therefore, in the present invention, the frequency response function of the whole spindle system can be obtained.

Then, the signal processor 120 transfers the information data on the frequency response function calculated through the above-described process to the analysis / compensation controller 130.

Meanwhile, the analysis / compensation controller 130 is, for example, a computer system with a built-in numerical analysis algorithm. The analysis / compensation controller 130 stores the initial stiffness coefficient and the attenuation coefficient measured while the main axis is in the optimal state, and the signal processor 120 By calculating the frequency response function received from the CEM using a numerical analysis algorithm, dynamic characteristics such as natural frequency and stiffness of the main axis are measured, and a comparison between the stiffness and attenuation coefficients obtained as a result of the measurement and the initial stiffness and attenuation coefficients stored in the The change amount is calculated, and a driving control signal (ie, a driving control signal for increasing or decreasing the rigidity of the main shaft) for driving the electromagnetic exciter is generated and transmitted to the exciter driver 140 based on the calculated change amount.

In addition, the exciter driver 140 may be configured to provide an excitation drive signal (PWM pulse) adaptive to the electromagnetic exciter 108 in response to a drive control signal from the analysis / compensation controller 130. It has a manual compensation mode for providing a drive signal (PWM pulse) to the electromagnetic exciter 108 in response to the drive control signal selected in accordance with the operation, such an exciter driver 140 is shown in FIG. It can be configured as shown.

3 is a block diagram of an exciter driver employable in the spindle bearing state control apparatus according to the present invention. The exciter driver 140 includes a first input selection block 302, a second input selection block 304, A channel selection block 306, a voltage adjusting block 308, a triangle wave generation block 310, a comparison block 312 and an amplification block 314. In addition, the comparison block 312 includes four comparators 312/1-312/4, and the amplification block 314 includes four amplifiers 314/1-314/4.

Referring to FIG. 3, the first input selection block 302 generates a sweep wave when executing the automatic compensation mode. The first input selection block 302 is configured to generate a sweep wave. In response, a sweep wave is generated and delivered to the channel selection block 306.

In addition, the second input selection block 304 generates any one of a signal (eg, a static signal, a manual shock signal, and an automatic shock signal) corresponding to the driver's operation when executing the manual compensation mode. 306). Here, the static signal is used to generate the excitation force to pull the main shaft with a constant force. It is used when the system is used as an actuator, and the manual shock signal is used to check the state of the ball bearing during operation. Each time the main axis has a main axis, the automatic shock signal is for generating a shock wave signal for the excitation every predetermined time interval (eg, 1 minute, 5 minutes, etc.).

Next, the channel selection block 306 is for the driver to select a channel in the manual compensation mode, and as shown in FIG. 2, the electromagnetic exciter has four channels (that is, 1083 / a-1083 / e channels, Four channel buttons are provided, assuming that they have 1083 / b-1083 / f channels, 1083 / c-1083 / g channels, and 1083 / d-1083 / h channels.

In addition, although not shown in FIG. 3, the voltage adjusting block 308 has a variable resistor, and adjusts the current amount to the corresponding channel by varying the voltage value of the selected channel according to the driver's operation. The triangular wave generation block 310 generates triangular wave signals and provides them to one end of each comparator 312/1-312/4 in the comparison block 312.

On the other hand, the comparison block 312 may be composed of, for example, four comparators 312/1-312/4, each comparator 312/1-312/4 is a triangular wave signal to a set of inputs The output from the voltage adjusting block 308 is input to the other end to generate a shock wave signal for excitation, that is, a PWM signal.

In addition, the amplification block 314 may be comprised of four amplifiers 314/1-314/4, each connected to the output of each comparator 312/1-312/4, with each corresponding comparator 312/1 312/4) amplifies the PWM signal output to the predetermined predetermined level and delivers it to the electromagnetic exciter 108 of FIG.

Therefore, the spindle bearing state control apparatus according to the present invention having the configuration as described above obtains the initial stiffness and initial attenuation of the spindle system by adjusting the spindle to an initial optimum state, and then frequency response function after a predetermined time of operating the spindle system again. To calculate the stiffness and damping coefficients of the spindle, compare the initial stiffness and damping coefficients with the stiffness coefficients and damping coefficients during operation, and obtain the amount of change, based on the calculated amount of change (stiffness and damping change of the spindle system). Therefore, by using the excitation force to compensate the control of the bearing stiffness, not only can the stability of the intelligent spindle system be improved, but also high speed and high accuracy can be expected.

As described above, according to the present invention, an intelligent main shaft is provided with an electromagnetic exciter to have a rotating shaft, a vibration sensor detects vibration during rotation, and analyzes a frequency response appearing in the detected vibration signal to stiffness the bearing. By detecting the state of the bearing such as change and preload, and controlling the driving of the exciter based on the detection result, it is possible to improve the stability of the intelligent spindle system because it controls the rotation degree and rigidity of the spindle optimally. In addition, high speed and high accuracy can be realized.

Claims (11)

A method of monitoring and compensating a bearing condition of a spindle system having a rotating shaft surrounded by a housing with a ball bearing interposed therebetween, Calculating and storing an initial stiffness coefficient and a damping coefficient of the spindle in a state in which the spindle system is set and operated in an optimal state; Detecting a vibration generated during operation of the spindle system and detecting a frequency change generated when the rotary shaft is rotated; Obtaining a frequency response function based on the detected vibration signal and the detected frequency change; Calculating a stiffness coefficient during operation and a damping coefficient during operation of the main shaft by analyzing the obtained frequency response function; And Comparing the initial stiffness coefficient and the damping coefficient with the calculated stiffness coefficient during operation and the damping coefficient during operation to detect the change amount, and based on the detected change amount, having an electromagnetic exciter mounted on a predetermined portion of the housing Spindle bearing state control method using electromagnetic excitation consisting of a process for compensating the change in the rigidity of the spindle. The method of claim 1, wherein the frequency response function is calculated as in the following equation. (In the above equation, F is force, X is displacement, M is mass, C is damping coefficient, and K is stiffness coefficient.) 3. The method of claim 1 or 2, wherein the method further comprises the step of exciting the electromagnetic exciter once with a predetermined constant excitation force each time the driver operates the button during operation of the spindle system. Spindle Bearing Condition Control Method Using Exciter. The spindle bearing state according to claim 1 or 2, wherein the method further comprises a step of exciting the electromagnetic exciter with a predetermined excitation force at a predetermined predetermined time interval according to a driver setting. Control method. An apparatus for monitoring and compensating a bearing condition of a spindle system having a rotating shaft surrounded by a housing with a ball bearing interposed therebetween, An electromagnetic exciter which excites the main axis with an excitation force corresponding to the shock wave signal provided from the outside, and generates a frequency change signal of the main axis generated during operation; A vibration sensor mounted on a predetermined portion of the housing to detect vibration generated in the spindle system; A signal processor obtaining a frequency response function based on the detected vibration signal and the detected frequency change signal; The obtained frequency response function is analyzed by a numerical analysis algorithm to calculate the stiffness coefficient during operation and the damping coefficient during operation of the main shaft, and the preset stored initial stiffness coefficient and the damping coefficient and the calculated stiffness coefficient during operation and the damping during operation. An analysis compensation controller comparing the coefficients to detect the change amount and generating an exciter drive control signal corresponding to the detected change amount; And Spindle bearing state using an electromagnetic exciter comprising an exciter driver which generates a shock wave signal for driving the exciter in response to the exciter drive control signal provided from the analysis compensation controller, and drives the electromagnetic exciter with the generated shock wave signal. controller. 6. The apparatus of claim 5, wherein the frequency response function is calculated as in the following equation. (In the above equation, F is force, X is displacement, M is mass, C is damping coefficient, and K is stiffness coefficient.) 6. The spindle bearing state control device according to claim 5, wherein the analysis compensation controller is a computer. 7. The vibrator driver according to claim 5 or 6, wherein: A first input selection block for generating a sweep wave signal corresponding to the exciter driving control signal provided from the analysis compensation controller when the automatic compensation mode of the control device is performed; A second input selection block which, when performing the automatic compensation mode of the control device, generates a shock wave signal for driving the electromagnetic exciter in response to a driver operation; A channel selection block having a plurality of channel selection buttons corresponding to the number of channels of the electromagnetic exciter, and transferring the shock wave signal to a selected channel when the driver selects any one of the plurality of channel selection buttons; A triangular wave generation block generating a triangular wave signal when the control device is operated; And And an comparing means for comparing the shock wave signal of the selected channel or the swept wave signal and the triangular wave signal, respectively, to generate a pulse signal for the corresponding excitation, and to transmit the pulse signal to the corresponding channel in the electromagnetic excitation device. Main spindle bearing state control device. 9. The apparatus of claim 8, wherein the shock wave signal includes a static signal, a passive shock wave signal, and an automatic shock wave signal. 9. The apparatus of claim 8, wherein the apparatus further comprises voltage adjusting means for manually adjusting a voltage level of the sweep wave or shock wave signal. 9. The apparatus of claim 8, wherein the apparatus further comprises amplifying means for amplifying the generated pulse signal to a predetermined predetermined level.