KR101184310B1 - Active compensated spindle, rotational accuracy compensating method using the same, and machining device having the same - Google Patents

Abstract

 The present invention relates to a spindle housing, a shaft rotatably installed in the spindle housing, the shaft being driven by a driver, and installed between the spindle housing and the shaft and between the spindle housing and the shaft by application of an electrical signal. Electromagnet unit for generating a; and a rotary sensor installed on one side of the shaft, the rotary sensor for measuring the rotational angle of the shaft during the rotational drive of the shaft, and a data portion including correction information of the rotational precision according to the rotational angle of the shaft And a controller configured to apply a control signal to the electromagnet unit based on the information of the rotary sensor and the data unit such that a control force corresponding to the rotation angle is applied to the shaft at each rotation angle of the shaft. The present invention relates to a processing apparatus provided with a shaft By each angle of rotation is applied to continuously control the shaft it is possible to improve the rotational accuracy of the spindle.

Description

ACTIVE COMPENSATED SPINDLE, ROTATIONAL ACCURACY COMPENSATING METHOD USING THE SAME, AND MACHINING DEVICE HAVING THE SAME}

The present invention relates to an active correction spindle configured to apply a control force to the shaft to improve the rotational accuracy during rotational drive of the shaft, a rotational precision correction method using the same, and a machining apparatus having the same.

The spindle used in a machining apparatus such as a lathe refers to an apparatus for rotating a machining object at a set speed. For example, in the case of a lathe, the workpiece is fixed to the spindle and rotated, and the cutting depth and the feed are given to the machining tool installed on the tool bar to cut the workpiece.

Recently, as the size of the object to be processed is miniaturized, the rotational accuracy of the spindle has emerged as an important problem. Air bearings and the like are used to improve rotational accuracy. However, even when air bearings and the like are used, a certain amount of rotational errors cannot be avoided due to manufacturing errors or techniques.

Nevertheless, if a precision of several tens of nanometers or less is required, active calibration is required to overcome these technical limitations, and various studies on active compensation of such a spindle have been conducted.

The present invention has been made in view of the above, and is intended to improve the rotational accuracy of the spindle by continuously applying a control force to the shaft at every rotational angle of the shaft.

In order to achieve the above object, the present invention provides a spindle housing, a shaft rotatably installed in the spindle housing and driven by a driver, and installed between the spindle housing and the shaft and by the application of an electrical signal. An electromagnet unit for generating a magnetic force between the spindle housing and the shaft, a rotary sensor installed at one side of the shaft, and measuring a rotational angle of the shaft during the rotational drive of the shaft, and a rotational precision according to the rotational angle of the shaft. A data unit including correction information, and a controller configured to apply a control signal to the electromagnet unit based on the information of the rotary sensor and the data unit such that a control force corresponding to the rotation angle is applied to the shaft for each rotation angle of the shaft. Active compensation spindle and lathe with same It discloses.

The electromagnet unit includes a magnetic core installed on an inner wall of the spindle housing and wound by a coil, and a rotor core installed on an outer circumferential surface of the shaft and disposed at a position facing the first magnetic core. The controller may be configured to adjust the strength or direction of the magnetic field generated in the magnetic core by adjusting the current amount or the direction of the current applied to the coil.

At the front end of the magnetic core may be additionally provided with a ring-shaped permanent magnet for generating a reference magnetic force for the rotor core.

The controller may be further connected to the controller for applying a control signal to the driver, in this case, the driver controller may be configured to receive the measurement information of the rotary sensor to apply to the controller.

A cover made of a magnetic material may be installed at the front end of the spindle housing so as to face the rotor core.

On the other hand, the present invention in the rotation accuracy correction method using the active correction type spindle, the step of calculating the correction information of the rotation accuracy by measuring the eccentric error according to the rotation angle of the shaft, and drives the shaft to rotate, Measuring a rotational angle of the shaft when the shaft is rotated, and applying a control force corresponding to the rotational angle to each of the rotational angles of the shaft based on information of the rotary sensor and the data unit; Disclosed is a method for correcting rotation accuracy using an active correction spindle.

According to the present invention having the above configuration, the control force corresponding to the rotation angle of the shaft can be applied variably, it is possible to improve the correction performance of the rotation accuracy.

In addition, according to the configuration as described above, it is possible to precise control of the three-axis direction control force applied to the shaft by adjusting the currents applied to each coil of the electromagnet unit.

1 is a perspective view of an active calibrated spindle according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the active calibrated spindle shown in FIG. 1. FIG.
Figure 3 is a block diagram of an active correction spindle according to an embodiment of the present invention.
4 is a view from the rear of the tip housing to which the electromagnet unit is mounted;
5 is an enlarged cross-sectional view of the electromagnet unit shown in FIG. 2.
6 is a graph showing an eccentric error according to the rotation angle of the shaft.

Hereinafter, an active correction spindle according to the present invention, a rotation precision correction method using the same, and a lathe having the same will be described in more detail with reference to the accompanying drawings.

1 is a perspective view of an active compensation spindle according to an embodiment of the present invention, Figure 2 is a cross-sectional view of the active compensation spindle shown in FIG. And, Figure 3 is a block diagram of an active correction spindle according to an embodiment of the present invention.

1 to 3, the active compensation spindle 100 includes a spindle housing 110, a shaft 120, a driver 130, an electromagnet unit 140, a rotary sensor 150, a data unit 160, And a controller 170.

The spindle housing 110 configures the appearance of the spindle and functions to rotatably receive the shaft 120. The spindle housing 110 may be configured by assembling a plurality of housings in the form of a cylinder. In this embodiment, the first and second intermediate housings 111 and 112, the front housing 113, and the rear housing 114 are assembled. The form is illustrated. A support 116 for supporting the spindle housing 110 is installed below the first intermediate housing 111. The support 116 has a structure that can be fixed to the installation surface of the processing device or measuring device.

The shaft 120 is installed to be relatively rotatable in the spindle housing 110, and one end of the shaft 120 is configured to be coupled with the workpiece. As the shaft 120 rotates, the workpiece also rotates with the shaft 120.

The journal bearing 117 may be installed between the shaft 120 and the first intermediate housing 111, and the axial direction (Z-axis direction) load of the shaft 120 may be provided on the first and second intermediate housings 111 and 112. Thrust bearings 118 supporting them may be installed.

The driver 130 is installed at one end of the shaft 120 and drives the shaft 120 to rotate. The driver 130 is in the form of an electric motor and is coupled to the outer circumferential surface of the shaft 120 end.

The electromagnet unit 140 is installed between the spindle housing 110 and the shaft 120, and serves to generate a magnetic force between the spindle housing 110 and the shaft 120 by the application of an electrical signal. When the driver 130 is installed at one end of the shaft 120, the electromagnet unit may be installed at the other end of the shaft. For example, the driver 130 may be installed at the rear end of the first intermediate housing 111, and the electromagnet unit 140 may be installed at the opposite side of the driver 130, that is, the front housing 113.

4 is a rear view of the tip housing on which the electromagnet unit is mounted, and FIG. 5 is an enlarged cross-sectional view of the electromagnet unit shown in FIG. 2.

The electromagnet unit 140 may include magnetic cores 141 to 144 installed on the inner wall of the spindle housing 110, and a rotor core 145 installed on the outer circumferential surface of the shaft 120.

The magnetic cores 141 to 144 are installed on the inner wall of the tip housing 113 and have a rod shape extending in the shaft 120 direction. The magnetic cores 141 to 144 are wound by the coils 141a to 144a and generate a magnetic field as current flows in the coils 141a to 144a. The magnetic cores 141 to 144 may be formed in the form of an iron core or in the form of a stacked core in which magnetic materials are stacked.

The magnetic cores 141 to 144 are first and second magnetic cores 141 and 142 installed in pairs along the Y-axis direction, and third and fourth magnetic cores 143 and 144 installed in pairs along the X-axis direction. It includes. The first and second magnetic cores 141 and 142 are disposed on both sides of the shaft 120 along the Y axis direction, and the third and fourth magnetic cores 143 and 144 are disposed on both sides of the shaft 120 along the X axis direction. do.

The rotor core 145 is formed of a magnetic material similarly to the magnetic cores 141 to 144 and is disposed at a position facing the magnetic cores 141 to 144. The rotor core 145 is a ring shape surrounding the outer circumferential surface of the shaft 120 and is fixed to the outer circumferential surface of the shaft 120. As the shaft 120 rotates, the rotor core 145 has a structure that rotates relative to the magnetic cores 141 to 144.

As a current flows in the coils 141a to 144a wound around the magnetic cores 141 to 144, a magnetic field is generated in the magnetic cores 141 to 144, and between the magnetic cores 141 to 144 and the rotor core 145. Attraction occurs due to the magnetic field, which acts as an external force on the shaft 120.

4 and 5, the magnetic field B1 generated by the first and second magnetic cores 141 and 142 is shown. The magnetic fields generated in the first and second magnetic cores 141 and 142 are formed in a loop shape along the periphery of the shaft 120. Although not shown in the drawing, the third and fourth magnetic cores 143 and 144 also generate a similar type of magnetic field.

The attractive force between the magnetic cores 141 to 144 and the rotor core 145 may be adjusted by adjusting the current flowing through the coils 141a to 144a. The magnitude and direction of the external force in the Y-axis direction can be adjusted by adjusting the amount of current and the direction of the current applied to the coils 141a and 142a wound on the first and second magnetic cores 141 and 142. In addition, it is possible to adjust the magnitude and direction of the external force in the X-axis direction by adjusting the current amount and the direction of the current applied to the coils 143a and 144a wound on the third and fourth magnetic cores 143 and 144.

Permanent magnets 148 generating a reference magnetic force with respect to the rotor core 145 may be installed at the tips of the magnetic cores 141 to 144. This embodiment illustrates that the permanent magnet 148 is formed in the shape of a circular ring. The permanent magnet 148 has N poles and S poles on both sides thereof. The permanent magnet 148 generates a magnetic field having a predetermined size even when no current is applied to the magnetic cores 141 to 144 and the coils 141a to 144a.

The shape of the permanent magnet 148 is not limited to the ring shape, and the permanent magnet 148 may be installed at the ends of each of the magnetic cores 141 to 144 as an independent structure (for example, a rectangular shape). have.

5 shows the magnetic fields B2 and B3 generated by the permanent magnet 148. According to this, the magnetic force lines coming from one surface of the permanent magnet 148 enter the other surface via the magnetic cores 141 to 144 and the rotor core 145. Due to such a magnetic field, a constant magnetic force is generated between the spindle housing 110 and the shaft 120.

The permanent magnet 148 is not an essential configuration for external force control between the spindle housing 110 and the shaft 120, but by installing the permanent magnet 148, the amount of current applied to the magnetic cores 141 to 144 can be reduced. The amount of current can also be easily adjusted.

A fixing ring 146 for fixing the magnetic cores 141 to 144 may be installed between the magnetic cores 141 to 144 and the permanent magnet 148. The fixing ring 147 may also be installed at the tip of the rotor core 145. These fixing rings 146 and 147 may be formed of a magnetic material such as steel.

A cover 115 of a magnetic material (for example, steel) is installed at the tip of the spindle housing 110. The cover 115 is fixed to the tip of the tip housing 113 and the shaft 120 is exposed to the outside of the cover 115. The cover 115 is installed to have a surface facing the portion where the rotor core 145 is installed. Some of the magnetic fields generated in the magnetic cores 141 to 144 are driven in the Z-axis direction, and the magnetic force generated thereby generates a relative external force between the rotor core 145 and the cover 115. Therefore, the external force in the Z-axis direction of the shaft 120 may also be adjusted by adjusting the magnetic field generated in the magnetic cores 141 to 144.

Referring back to FIG. 2, the rotary sensor 150 is installed at one side of the shaft 120 and measures the rotation angle of the shaft 120 when the shaft 120 is driven to rotate. The rotary sensor 150 is installed on one side of the driver 130 and may be implemented as various types of rotary encoders.

The data unit 160 has a function of storing information regarding correction of rotation accuracy according to the rotation angle of the shaft 120, and has a form capable of storing information such as a memory. The correction information of the rotation accuracy can be detected by measuring the eccentric error of the shaft 120 in advance. The sensor is attached to the shaft 120 and the shaft 120 is rotated by the driver 130 to measure the eccentric error of the shaft 120.

6 is a graph showing an eccentric error according to the rotation angle of the shaft.

The solid line in the graph of FIG. 6 represents an eccentric distance from the reference position (dotted line) at the corresponding angle, and accordingly, it can be seen that the eccentric distance varies irregularly for each rotation angle of the shaft 120. These graphs can be obtained for the X, Y, and Z axis directions using three-axis sensors, respectively.

According to the present invention, the rotational accuracy is compensated by applying an external force to the shaft 120 so as to eliminate the eccentric error as described above. That is, after the displacement of the shaft 120 is calculated in advance for each rotation angle of the shaft 120, external force is applied in a direction to compensate for the eccentricity of the shaft 120 for each angle. Based on the eccentric error as shown in FIG. 4, the external force to be applied to the shaft 120 can be calculated for each X, Y, and Z axis direction, and the amount of current and the current direction to be applied to each coil 141a to 144a are calculated from this. Can be calculated. The information calculated in this way is stored in the data unit 160, which may be automatically calculated and stored by a predetermined algorithm.

The controller 170 is electrically connected to the rotary sensor 150 and the data unit 160, and applies a control signal to the electromagnet unit 140 based on the information applied therefrom.

The controller 170 adjusts the amount of current or the current direction applied to each of the coils 141a to 144a so that a control force corresponding to the rotational angle is applied to the shaft 120 at each rotational angle of the shaft 120. Here, the controller 170 individually applies a control signal to the coils 141a to 144a wound on the first to fourth magnetic cores 141 to 144.

For reference, the control unit 170 is a concept including a configuration for supplying a current to each coil (141a to 144a). However, a current supply unit for supplying current may be separately provided between the controller 170 and the electromagnet unit 140. In this case, the controller 170 controls the operation of the current supply unit.

The driver 170 for controlling the driver 130 may be connected to the controller 170. The driver controller 175 receives the measurement information (rotation angle) of the rotary sensor 150 continuously (or at a predetermined angle) during rotation driving of the shaft 120, and applies it to the controller 170. The controller 170 matches a rotation angle applied by the rotary sensor 150 with correction information (ie, information on current to be applied to each coil) at the rotation angle, and then corresponds to a current corresponding to each rotation angle. Is applied to each of the coils 141a to 144a.

When the eccentric position of the shaft 120 changes irregularly as shown in the graph of FIG. 6 while the shaft 120 rotates once, the controller 170 is variable to the shaft 120 according to the rotation angle of the shaft 120. Ensure control is continuously applied.

In the present exemplary embodiment, the driver controller 175 for controlling the driver 130 is separately provided. However, the driver controller 175 may be integrally formed with the controller 170.

The method of correcting the rotation accuracy using the active correction spindle of the present invention is as follows.

First, as described above, the correction information of the rotation precision is calculated by measuring the eccentricity error according to the rotation angle of the shaft 120 using the sensor. The correction information includes the current amount and the current direction to be applied to each coil 141a to 144a for each rotation angle of the shaft 120, which is stored in the data unit 160 and applied to the controller 170.

Next, the shaft 120 is driven to rotate, and the rotation angle of the shaft 120 is measured when the shaft 120 is driven to rotate. Information about the rotation angle detected by the rotary sensor 150 is continuously applied to the control unit 170 (or at a predetermined time interval).

Next, the correction information of the data unit 160 and the rotation information of the shaft 120 are matched so that a control signal corresponding to each rotation angle of the shaft 120 is applied to the electromagnet unit 140, thereby providing a rotation angle for each rotation angle. Corresponding control force is applied to the shaft 120. This process is repeated every time the shaft 120 continues to rotate, bar control force corresponding to it can be applied variably for each rotation angle, it is possible to improve the correction performance of the rotation accuracy.

The active compensation spindle 100 described above is applicable to a processing apparatus, a measuring apparatus, etc. for processing or measuring a processing object. The machining device (or measuring device) rotates the object (or measurement object) using the active compensation spindle 100, and cuts the object (or measurement object) that is rotated using the tool module (or measurement module). It has a structure to measure (or measure). The active compensation spindle 100 of the present invention can be applied to various devices such as ultra precision lathes, laser processing machines, measuring machines, and the like.

In the above described with reference to the accompanying drawings, the active correction spindle according to the present invention, a rotation precision correction method using the same, and a processing apparatus having the same, the present invention is limited by the embodiments and drawings disclosed herein Various modifications may be made by those skilled in the art without departing from the spirit of the present invention.

Claims (11)

Spindle housing;
A shaft rotatably installed in the spindle housing and rotatably driven by a driver;
An electromagnet unit installed between the spindle housing and the shaft and generating a magnetic force between the spindle housing and the shaft by application of an electrical signal;
A rotary sensor installed at one side of the shaft and measuring a rotation angle of the shaft when the shaft is driven to rotate;
A data unit including correction information of rotation accuracy according to the rotation angle of the shaft; And
A control unit for applying a control signal to the electromagnet unit based on the information of the rotary sensor and the data unit such that a control force corresponding to the rotation angle is applied to the shaft at each rotation angle of the shaft,
Information related to the control force corresponding to the rotation angle is calculated based on an eccentric error corresponding to the rotation angle of the shaft measured in advance, and stored in advance in the data unit,
And the control unit outputs a control signal corresponding to the rotation angle of the shaft by matching the rotation angle of the shaft applied from the rotary sensor with the information related to the control force stored in the data unit. The method of claim 1, wherein the electromagnet unit,
A magnetic core installed on an inner wall of the spindle housing and wound by a coil;
Is installed on the outer circumferential surface of the shaft, comprising a rotor core of a magnetic material disposed in a position facing the magnetic core,
And the controller controls the strength or direction of the magnetic field generated in the magnetic core by adjusting the current amount or the direction of the current applied to the coil. The method of claim 2, wherein the magnetic core,
First and second magnetic cores installed in pairs along the Y-axis direction; And
It includes a third and fourth magnetic core installed in pairs along the X axis direction,
And the controller is configured to apply a control signal to the first to fourth magnetic cores individually. The method of claim 2,
And the rotor core has a ring shape surrounding the outer circumferential surface of the shaft. The method of claim 2,
And the rotation accuracy correction information includes information on a current to be applied to the magnetic core. The method of claim 2,
And a permanent magnet installed at the front end of the magnetic core, the permanent magnet generating a reference magnetic force with respect to the rotor core. The method of claim 3,
Further comprising a cover installed to the front end of the spindle housing facing the rotor core,
The cover has an active compensation spindle, characterized in that having a magnetic material to adjust the external force in the Z-axis direction of the shaft through the magnetic field control generated in the first to fourth magnetic core. The method of claim 1,
The driver is installed at one end of the shaft,
And the electromagnet unit is installed at the other end of the shaft. The method of claim 1,
And a driver controller for applying a control signal to the driver and receiving the measurement information of the rotary sensor and applying the measured information to the controller. In the method of correcting the rotation accuracy using the active correction spindle according to any one of claims 1 to 9,
Calculating correction information of rotation accuracy by measuring an eccentric error according to the rotation angle of the shaft;
Driving the shaft in rotation and measuring a rotational angle of the shaft when the shaft is in rotation; And
And matching a rotation angle of the shaft applied from the rotary sensor with information related to the control force stored in the data unit, and applying a control force corresponding to the rotation angle to the shaft for each rotation angle of the shaft. Rotation accuracy correction method using an active correction type spindle. A tool module for cutting the processing object; And
A processing apparatus comprising an active compensation spindle according to any one of claims 1 to 9 for rotating the object to be processed when the object is to be processed.

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