JP2012206188A - High-precision processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-precision processing apparatus that can perform high-precision processing by preventing a tool from being bent due to processing loads such as cutting resistance and grinding resistance to.SOLUTION: The high-precision processing apparatus includes a tool 4 having a columnar processing surface and rotating the processing surface by a rotary shaft 24, and performs processing by bringing the columnar processing surface of the tool 4 into contact with a workpiece 1 while rotating the columnar processing surface. The high-precision processing apparatus includes: a circling drive motor 5 for allowing the rotary shaft 24 of the tool 4 to circle in a horizontal direction relative to the workpiece 1; a torque sensor 17 for acquiring both output values of the circling drive motor 5 during processing and non-processing; a calculating part 14 for calculating the bending amount of the tool 4 relative to the rotary shaft 24 based on the output values of the circling drive motor 5 during processing and non-processing to determine the circling amount of a circling for balancing the bending amount; and a control part 16 for controlling the circling drive motor 5 so that the rotary shaft 24 of the tool 4 is situated by the circling amount of the circling.

Description

  The present invention relates to a high-precision machining apparatus that obtains high-precision straightness, straightness, cylindricity, flatness, and other shape accuracy in a short time, and is particularly caused by machining loads such as cutting resistance or grinding resistance. It is intended to improve the machining accuracy by accurately correcting the deflection of the tool.

  The conventional high-precision processing apparatus has a problem in that dimensional accuracy deteriorates due to thermal deformation caused by heat generated from the drive motor, frictional heat from the sliding surface of the table, cutting heat generated from the processing point, and the like. In addition, if the tool is accidentally chucked diagonally with respect to the spindle axis, the outer diameter of the chuck and cutting teeth of the tool is eccentric, or the tool is eccentrically chucked, the tool rotates. In this case, the envelope of the outer diameter of the cutting edge portion is the sum of the outer diameter of the tool and the amount of runout, and the groove width to be machined has a problem that a machining error corresponding to the amount of runout of the tool occurs.

  Therefore, in the conventional high-precision processing equipment, the position of the rotating tool is measured by a measuring instrument installed on the processing machine, and the change in relative position with respect to the workpiece is obtained to include an error due to thermal displacement. By calculating the outer diameter of the upper tool and inputting the apparent outer diameter of the tool to the NC control unit, the tool coordinates in the NC control unit are corrected in-line, and high dimensional accuracy is obtained. (For example, see Patent Document 1).

  Further, when the machining speed is increased in order to shorten the machining time, the machining load increases, and the tool is bent due to the influence. For this reason, workpieces that require high shape accuracy have been processed at a lower processing speed, which has a problem that the processing time becomes longer. Therefore, the conventional high-precision machining device estimates the amount of tool deflection from the spindle spindle motor current or spindle spindle power, and tilts the spindle spindle relative to the workpiece in accordance with the tool deflection amount. High shape accuracy is obtained (see, for example, Patent Document 2).

Japanese Patent No. 4172450 Japanese Patent No. 375886

  The conventional processing method of the former high-precision processing apparatus is for improving the dimensional accuracy of the workpiece, and there is a problem that the shape accuracy such as the perpendicularity, cylindricity, and flatness of the workpiece cannot be improved. there were. In the latter high-precision machining apparatus, the amount of tool deflection is estimated from the motor current of the spindle spindle or the power of the spindle spindle. The motor current of the spindle main shaft or the power of the spindle main shaft changes according to the main component force acting in the tangential direction of the tool in the machining load. There is a problem that the accuracy of estimating the amount of bending of the tool is poor because it works in the radial direction of the tool and directly measures the back component force that causes the bending of the tool, and it cannot cope with the fluctuation of the machining load.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a high-precision machining apparatus that can accurately measure the deflection of a tool and improve machining accuracy.

This invention
In a high-precision machining apparatus that has a cylindrical machining surface and includes a tool that rotates the machining surface with a rotation axis, and performs machining by contacting the workpiece while rotating the cylindrical machining surface of the tool.
A turning drive motor for turning the rotation axis of the tool horizontally with respect to the workpiece;
A sensor for obtaining an output value at the time of non-machining and an output value at the time of machining of the turning drive motor;
An operation for calculating a turning amount of the turning for eliminating the bending amount by calculating a bending amount with respect to the rotation axis of the tool from an output value at the time of non-machining of the turning drive motor and an output value at the time of machining. And
And a control unit that controls the turning drive motor so that the rotation axis of the tool becomes the turning amount of the turning.

The high-precision machining apparatus of the present invention is
In a high-precision machining apparatus that has a cylindrical machining surface and includes a tool that rotates the machining surface with a rotation axis, and performs machining by contacting the workpiece while rotating the cylindrical machining surface of the tool.
A turning drive motor for turning the rotation axis of the tool horizontally with respect to the workpiece;
A sensor for obtaining an output value at the time of non-machining and an output value at the time of machining of the turning drive motor;
An operation for calculating a turning amount of the turning for eliminating the bending amount by calculating a bending amount with respect to the rotation axis of the tool from an output value at the time of non-machining of the turning drive motor and an output value at the time of machining. And
A control unit that controls the turning drive motor so that the rotation axis of the tool becomes the turning amount of the turning,
Since the bending of the tool due to the machining load such as cutting resistance or grinding resistance is eliminated by measuring the reaction force against the back component force, high-precision machining can be performed.

It is a perspective view which shows the structure of the high precision processing apparatus of Embodiment 1 of this invention. It is a top view which shows the structure of the high precision processing apparatus shown in FIG. It is a side view which shows the structure of the high precision processing apparatus shown in FIG. It is a schematic diagram for demonstrating the relationship between the turning amount of the front-end | tip of the tool of the high precision processing apparatus shown in FIG. 1, and the displacement amount of a displacement sensor. It is the schematic diagram seen from the rotating shaft direction of the tool for demonstrating the relationship of the processing load of the tool and workpiece | work of the high precision processing apparatus shown in FIG. It is the schematic diagram seen from upper direction for demonstrating the relationship of the processing load in the high precision processing apparatus shown in FIG. It is a figure which shows the state of the tool bent by the influence of the back component force of a high precision processing apparatus. It is a figure which shows the state which turned the tool according to the deflection amount of the tool of the high precision processing apparatus in Embodiment 1 of this invention. It is a schematic diagram for demonstrating the relationship between the back component force and the reaction force with respect to a back component force of the high precision processing apparatus shown in FIG. It is a top view which shows the structure of the high precision processing apparatus of Embodiment 2 of this invention.

Embodiment 1 FIG.
Embodiments of the present invention will be described below. 1 is a perspective view of the configuration of a high-precision machining apparatus according to Embodiment 1 of the present invention, FIG. 2 is a top view showing the configuration of the high-precision machining apparatus shown in FIG. 1, and FIG. 3 is the high-precision machining apparatus shown in FIG. FIG. 4 is a side view showing the configuration of the machining apparatus, FIG. 4 is a schematic diagram for explaining the relationship between the turning amount of the tool tip of the high-precision machining apparatus shown in FIG. 1 and the displacement amount of the displacement sensor, and FIG. FIG. 6 is a schematic view seen from the direction of the rotation axis of the tool for explaining the relationship between the machining load of the tool and workpiece of the high-precision machining apparatus shown in FIG. 6, and FIG. 7 is a schematic diagram viewed from above, FIG. 7 is a diagram showing the state of the tool bent under the influence of the back component force of the high-precision machining apparatus, and FIG. 8 is a diagram showing the high level in Embodiment 1 of the present invention. The figure which shows the state which turned the tool according to the deflection amount of the tool of a precision processing apparatus, FIG. 9 is the height shown in FIG. It is a schematic view for explaining the relationship between the reaction force against the back component force and back component force in degrees machining apparatus.

In the drawing, a high-precision machining apparatus performs high-precision straightness, straightness, cylindricity, flatness, and other shapes in a short time, and includes a tool 4 for machining a workpiece 1, a workpiece 1 and a tool 4. In order to change the relative distance between the Z axis table 20 that is movable relative to the Z axis that is the thickness direction of the workpiece 1 and the X axis that is orthogonal to the Z axis and that is the feed direction of the tool 4 A movable X-axis table 21, a Y-axis table 22 movable relative to a Y-axis orthogonal to the Z-axis and the X-axis, respectively, and a rotating shaft 24 of the tool 4 with respect to the workpiece 1 are turned in the horizontal direction. A turning drive motor 5;
A ball screw 6 driven by the turning drive motor 5, a torque sensor 17 as a sensor for detecting an output torque using the output value when the turning drive motor 5 is not processed and the output value when processed as an output value of the turning drive motor 5, A work spindle 2 mounted on the Y-axis table 22 and holding the work 1 and rotating on the central axis 23, and a tool spindle 3 holding the tool 4 at a position facing the work 1 and rotating on the rotary shaft 24. With.

  Further, a spindle holder 8 for holding the tool spindle 3, a turning base 7 on which the spindle holder 8 is placed, a turning guide 9 formed on the lower surface of the turning base 7, and an X-axis table 21. A lower base 25 for installing the turning guide 9 on the upper surface, a displacement sensor 10 for detecting a relative displacement amount between the lower base 25 and the turning base 7, a motor driver 11 for driving and controlling the turning drive motor 5, A first converter 15 that converts the signal of the torque sensor 17; a second converter 12 that converts the signal of the displacement sensor 10; and a data center 13 that stores the value of the output torque of the turning drive motor 5 when not processed. In order to eliminate the deflection amount, the deflection amount of the tool 4 with respect to the rotary shaft 24 is calculated from the output torque value stored in the data center 13 and the output torque value at the time of machining. A calculation unit 14 that determines a turning amount of the turning of the rotating shaft 24 of the tool 4 and a control unit that drives the turning drive motor 5 by controlling the motor driver 11 so that the rotating shaft 24 of the tool 4 has a turning amount of turning. 16.

  The tool 4 has a cylindrical machining surface, and the machining surface rotates on the rotation shaft 24 via the tool spindle 3. Then, machining is performed by contacting the workpiece 1 while rotating the cylindrical machining surface of the tool 4. Then, in order to make a turning around the machining point A in a plane including the machining point A and the rotating shaft 24 of the tool 4 by the drive of the turning drive motor 5, the turning guide 9 has a Y axis passing through the machining point A. It is formed in an arc shape centered on the direction axis. Therefore, by driving the turning drive motor 5, the turning base 7, the spindle holder 8, the tool spindle 3, and the tool 4 are turned along the turning guide 9 through the ball screw 6. The tool 4 is driven relative to the workpiece 1 in the X-axis direction, the Y-axis direction, and the Z-axis direction using the X-axis table 21, the Y-axis table 22, and the Z-axis table 20, thereby 1 can be processed into an arbitrary shape.

The operation of the high precision machining apparatus of the first embodiment configured as described above will be described. First, the turning amount h3 at the tip of the tool 4 will be described with reference to FIG. The turning amount h3 of the tip of the tool 4 can be obtained by obtaining the displacement amount of the turning base 7 measured by the displacement sensor 10, that is, the displacement amount of the displacement sensor 10 through the second converter 12.
That is, when the ratio of the distance h1 from the turning center point B to the tip of the tool 4 and the distance h2 from the turning center point B to the position of the displacement sensor 10 is, for example, 1: 5, the turning amount h3 at the tip of the tool 4 is It becomes 1/5 of the displacement amount h4 of the displacement sensor 10 and can be detected. In addition, although the example which detects the turning amount of the turning base 7 was shown, it can also be calculated from the turning amount of the spindle holder 8.

  Next, the machining load F will be described with reference to FIGS. The machining load F on the workpiece 1 of the tool 4 can be decomposed into a main component force Fc and a back component force Ft. The main component force Fc is a tangential force at the machining point A of the tool 4 and is an element that determines the magnitude of the power required to rotate the tool spindle 3. Further, the back component force Ft is a force in the radial direction at the processing point A of the tool 4, that is, a force pressing the tool 4 against the workpiece 1, and is an element by which the tool 4 bends.

Next, the relationship between the deflection amount Y of the tool 4 with respect to the rotating shaft 24 and the back component force Ft will be described with reference to FIG. As is clear from FIG. 7, the deflection amount Y is the same as the deflection amount of the tool 4 with respect to the rotating shaft 24. When the back component force Ft shown above is applied to the machining point A on the tool 4, the tool length of the tool 4 is L, the distance from the tip of the tool 4 to the machining point A is L1, and the difference between L1 and L1 Is L2, the longitudinal elastic modulus of the tool 4 is E, and the moment of inertia of the cross section is I, the bending amount Y of the tool 4 is expressed by the following equation (1) from the bending equation of the cantilever.
Y = (Ft × L2 ³ / (3 × E × I)) × (1+ (3 × L1) / (2 × L2))
L1 and L2 are numerical values determined in advance according to machining conditions, E is determined according to the material of the tool 4, and I is determined according to the cross-sectional shape of the tool 4, respectively. Therefore, if the back component force Ft is known, the deflection amount Y of the tool 4 can be estimated.

  Factors that cause the machining load F to fluctuate include runout of the workpiece 1 caused by misalignment between the workpiece 1 and the workpiece spindle 2, runout of the tool 4 caused by misalignment between the tool 4 and the tool spindle 3, and the workpiece before machining. The shape accuracy of 1 and the change of the state of the tool 4 due to processing can be mentioned. If the machining load F fluctuates due to such factors, the back component force Ft shown above fluctuates accordingly, and the amount of deflection of the tool 4 also fluctuates. That is, the tool 4 bends due to the influence of the back component force Ft, and as a result, the perpendicularity of the workpiece 1 deteriorates as shown in FIG. Moreover, since the back component force Ft fluctuates for every part which processes the workpiece | work 1, the deflection amount of the tool 4 fluctuates. As a result, since the perpendicularity of the workpiece 1 changes for each part to be machined, the swell as shown in FIG.

  In order to solve this problem, in Embodiment 1 of the present application, as shown in FIG. 8, the tool spindle 3 is turned around the processing point A in the direction in which the tool 4 is pressed against the workpiece 1. The turning amount of the tool spindle 3 at this time is for eliminating the bending amount Y of the tool 4 and is the amount by which the tip of the tool 4 moves. Therefore, the deflection amount Y of the tool 4 is detected during machining, and the turning amount of the tool spindle 3 is adjusted according to the deflection amount Y.

  However, the direct measurement of the deflection amount Y of the tool 4 during machining means that vibration due to machining load, the influence of cutting water and grinding water, and the work 1 rotates at a higher speed than during normal measurement. This is difficult. Therefore, the above-described back component force Ft is measured and detected. The back component force Ft during processing is transmitted to the turning drive motor 5 via the turning base 7 and the ball screw 6. In other words, the turning drive motor 5 during processing outputs a drive force having a magnitude obtained by adding a drive force for holding the tool spindle 3 in place and a reaction force Ft ′ against the back component force Ft.

Therefore, first, the output torque of the turning drive motor 5 at the time of non-machining as a driving force for holding the tool spindle 3 in place is measured using the torque sensor 17, and the data is transmitted via the first converter 15. Accumulate in the center 13. Next, the output torque of the turning drive motor 5 being processed is measured by the torque sensor 17.
Next, the result of calculating the difference between the output torque during non-machining and the output torque during machining by the calculation unit 14 corresponds to the reaction force Ft ′ with respect to the back component force Ft. By repeating this calculation during machining, a reaction force Ft ′ with respect to the back component force Ft can be obtained in accordance with the machining location.

  Next, the relationship between the back component force Ft and the reaction force Ft 'with respect to the back component force Ft will be described with reference to FIG. When the ratio of the distance h5 from the turning center point B to the machining point A and the distance h6 to the turning drive motor 5 is, for example, 1: 5, 1/5 of the reaction force Ft ′ to the back force Ft is the back force. Corresponds to Ft. The deflection amount Y of the tool 4 can be calculated by substituting the estimated back component force Ft into the above equation (1). Then, the reaction force Ft ′ with respect to the back component force Ft is detected for each processed part, and the deflection amount Y of the tool 4 can be calculated for each processed part.

As described above, when the ratio of the distance h1 from the turning center point B to the tip of the tool 4 and the distance h2 to the displacement sensor 10 is 1: 5, the displacement amount of the displacement sensor 10 is the deflection amount Y. The turning drive motor 5 is driven so as to be 5 times. By adjusting the drive amount of the turning drive motor 5 for each machining location, it is possible to obtain a workpiece 1 that can be machined with a good squareness and in which the waviness of the machining surface is suppressed.
In the first embodiment, the example in which the displacement sensor 10 is used as a sensor for monitoring the displacement amount of the turning base 7 is shown. However, the present invention is not limited to this, and an encoder is installed in the turning drive motor 5. Even if this encoder is used, the same operation can be performed.

  According to the first embodiment, the reaction force against the back component force that causes the bending of the tool is measured, and even if the machining load fluctuates during machining, the turning amount of the tool turning is adjusted according to this fluctuation. It becomes possible to obtain a highly accurate shape accuracy. Further, since the output value of the drive motor is measured by the output torque, the measurement accuracy is improved.

Embodiment 2. FIG.
In the first embodiment, an example in which the output torque is used as the output value of the turning drive motor 5 is shown. However, the present invention is not limited to this, and as shown in FIG. It is possible to install the wattmeter 18 as a sensor for measuring the output power as the output value of the turning drive motor 5 and detect the output power using the wattmeter 18 to perform the same as in the first embodiment. The same effects as those of the first embodiment can be obtained. Furthermore, in this case, since the active power can be measured even if the phase of the voltage and the current does not match, high measurement accuracy can be obtained. Further, since it is not necessary to install the power meter and the turning drive motor close to each other, it is possible to reduce the size of the periphery of the turning drive motor.

Embodiment 3 FIG.
In the second embodiment, an example in which the output power from the motor driver 11 to the swing drive motor 5 is measured has been described. However, the present invention is not limited to this, and the output current from the motor driver 11 to the swing drive motor 5 is measured. As an output value of the swing drive motor 5, an ammeter as a sensor is installed instead of the wattmeter 18 at the same location as the wattmeter 18 of the second embodiment, and an output current is measured. And the same effects as those of the above-described embodiments can be obtained. Further, in this case, an ammeter for measuring the output current is inexpensive and the cost can be reduced. In addition, since it is not necessary to install the ammeter and the swing drive motor close to each other, it is possible to reduce the size of the periphery of the swing drive motor. Moreover, since it is small compared with a wattmeter, the periphery of a control part can also be reduced in size.

  In each of the above-described embodiments, an example is shown in which the workpiece 1 is rotated by the workpiece spindle 2 to perform machining. However, the present invention is not limited to this. This can be performed in the same manner as the embodiment, and the same effect can be obtained.

  In each of the above embodiments, an example including the Z-axis table 20, the X-axis table 21, the Y-axis table 22, and the like has been described. However, the present invention is not limited to this. This can be performed in the same manner as in the embodiment, and the same effect can be obtained.

1 work, 2 work spindles, 3 tool spindles, 4 tools,
5 slewing drive motor, 11 motor driver, 14 calculation unit, 16 control unit,
17 Torque sensor, 18 Wattmeter, 20 Z-axis table, 21 X-axis table,
22 Y-axis table, 24 rotation axis, A machining point, B turning center point.

Claims (6)

In a high-precision machining apparatus that has a cylindrical machining surface and includes a tool that rotates the machining surface with a rotation axis, and performs machining by contacting the workpiece while rotating the cylindrical machining surface of the tool.
A turning drive motor for turning the rotation axis of the tool horizontally with respect to the workpiece;
A sensor for obtaining an output value at the time of non-machining and an output value at the time of machining of the turning drive motor;
An operation for calculating a turning amount of the turning for eliminating the bending amount by calculating a bending amount with respect to the rotation axis of the tool from an output value at the time of non-machining of the turning drive motor and an output value at the time of machining. And
A high-precision machining apparatus, comprising: a control unit that controls the turning drive motor so that a rotation axis of the tool becomes a turning amount of the turning. The high-precision machining apparatus according to claim 1, wherein an output value of the turning drive motor is obtained from an output torque of the turning drive motor. The high precision machining apparatus according to claim 1, wherein the output value of the turning drive motor is obtained from output power from a motor driver to the turning drive motor. The high precision machining apparatus according to claim 1, wherein the output value of the turning drive motor is obtained from an output current from a motor driver to the turning drive motor. A work spindle that holds and rotates the work;
A tool spindle that holds the tool at a position facing the workpiece and rotates on the rotating shaft;
In order to change the relative distance between the workpiece and the tool, the Z-axis which is the thickness direction of the workpiece, the X-axis which is orthogonal to the Z-axis and which is the feed direction of the tool, the Z-axis and the X-axis Each having a Y axis perpendicular to
The said turning drive motor performs the said turning centering | focusing on the said processing point in the plane containing a processing point and the rotating shaft of the said tool, It is any one of Claim 1 thru | or 4 characterized by the above-mentioned. High precision processing equipment. A holding unit for holding the workpiece;
A tool spindle that holds the tool at a position facing the workpiece and rotates on the rotating shaft;
In order to change the relative distance between the workpiece and the tool, the Z-axis which is the thickness direction of the workpiece, the X-axis which is orthogonal to the Z-axis and which is the feed direction of the tool, the Z-axis and the X-axis Each having a Y axis perpendicular to
The said turning drive motor performs the said turning centering | focusing on the said process point in the plane containing a process point and the rotating shaft of the said tool. High precision processing equipment.

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