JPH0825101A - Ultra-precision cutting device and method by piezoelectric position control - Google Patents

Abstract

(57) [Summary] [Purpose] It has a plurality of cutting tools, and the cutting edge position of the cutting tools can be freely adjusted in a short time, thereby coping with the change of the cutting edge position due to wear or the like. The present invention provides an ultra-precision cutting device and method by piezoelectric position control that can adjust the position of a cutting edge in a short time, can continue ultra-precision cutting for a long time, and can perform ultra-precision cutting more efficiently than conventional methods. A rotary driving device for holding and rotating a workpiece, a plurality of tools for holding a plurality of tools at intervals, and a tool for finely displacing a tool position, and a tool for rotating a tool. A moving table 16 that moves orthogonally to the rotation axis. The tool 20 is
It has a cutting tool holding plate 22 for holding a plurality of cutting tools, and a piezoelectric element 24 for supporting the cutting tool holding plate at three points and displacing the supporting point minutely in parallel with the rotation axis. The plate is slightly displaced to adjust the positions of the cutting edges of the plurality of cutting tools, and the workpiece is cut with the plurality of cutting tools.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-precision cutting device and method for controlling the position of a plurality of cutting tools using a piezoelectric element.

[0002]

2. Description of the Related Art The limit of the accuracy of cutting processing has been improved with the times, and at present, ultra-precision cutting of 0.1 μm or less can be performed on a limited object. One example of such ultra-precision cutting is a processing method called “single-point diamond turning”, in which a single-crystal diamond tool and an ultra-precision lathe are used to cut the work with a single tool while rotating the work with a lathe, and then use a soft metal. (aluminum,
Copper, etc.) can be mirror-finished with high precision. Such ultra-precision cutting is applied to laser optical components, computer disk materials, VTR cylinders, laser disks, and the like.

[0003]

However, in the conventional ultra-precision cutting, a precise mirror surface can be obtained, but there is a problem that the cutting efficiency is low because the cutting is performed with one cutting tool. For this reason, there has been a demand for an ultra-precision cutting method capable of increasing the processing efficiency by simultaneously using a plurality of cutting tools and performing mirror surface cutting.

[0004] In order to satisfy such demands, there is known a method of processing a polygon mirror used for a laser printer or the like. In this processing method, as schematically shown in FIG. 10, a tool 2 (fly cut tool) having two cutting tools 1 is rotated to cut each surface of the polygon mirror 3 having a hexagonal prism. The two tools 1 are slightly displaced from each other, so that high efficiency cutting can be performed by simultaneously operating the two tools, and a mirror surface can be obtained by operating only one of the tools. .

[0005] However, in machining using a fly-cut tool, the cutting edge position of the cutting tool cannot be freely adjusted because the cutting tool 1 is fixed, so that it takes time to adjust the cutting edge position before machining and wear and the like. Therefore, when the position of the cutting edge is changed, there is a problem that the blade cannot be used in a short time.

The present invention has been made to solve such a problem. That is, an object of the present invention is to have a plurality of cutting tools, and to be able to freely adjust the cutting edge positions of the plurality of cutting tools in a short time, thereby coping with the change in the cutting edge position due to wear or the like. It is an object of the present invention to provide an ultra-precision cutting device and method by piezoelectric position control that can adjust the position of a blade edge in a short time and perform ultra-precision cutting for a long time while performing ultra-precision cutting with higher efficiency than conventional methods.

[0007]

According to the present invention, there is provided a rotary drive device for holding and rotating a workpiece and a bit displacement device for holding a plurality of bits at an interval and minutely displacing the bit position. A moving table for moving the bite displacement device orthogonally to a rotation axis of a rotary driving device, wherein the bite displacement device supports a bite holding plate for holding a plurality of bits, and the bite holding plate at three points. A piezoelectric element for minutely displacing the support point in parallel with the rotation axis, and applying a voltage to the piezoelectric element to minutely displace the bite holding plate to adjust the positions of the cutting edges of the plurality of bits, thereby forming a cover. An ultra-precision cutting device by piezoelectric position control, characterized in that a workpiece is cut with a plurality of cutting tools.

According to a preferred embodiment of the present invention, the bite displacement device further includes a base positioned substantially parallel to the bite holding plate and fixed to the moving table, and a pressurizing device for urging the bite holding plate toward the base side. An apparatus and an elastic support device for elastically holding the cutting tool holding plate and preventing movement perpendicular to the rotation axis, wherein the piezoelectric element is sandwiched between the cutting tool holding plate and the base. Further, the bite displacement device further has a position sensor for detecting displacement of the support point.

Further, according to the present invention, a work holding plate for holding and rotating a workpiece and supporting a plurality of tools is supported by three piezoelectric elements, and a voltage is applied to the piezoelectric elements to support points. Is finely displaced in parallel with the rotation axis of the workpiece to adjust the positions of the cutting edges of the plurality of tools, and then the plurality of tools are moved orthogonally to the rotation axis, thereby cutting the workpiece with the plurality of tools. An ultra-precision cutting method by piezoelectric position control, characterized by processing.

[0010]

According to the apparatus and method of the present invention, a tool for displacing a tool includes a tool for holding a plurality of tools, a tool for supporting the tool at three points, and a support point parallel to the rotation axis. Since the piezoelectric element has a piezoelectric element for performing minute displacement, the supporting point is minutely displaced in parallel with the rotation axis of the workpiece by the piezoelectric element, thereby causing the bite holding plate to perform minute displacement and small tilt parallel to the rotation axis. It is possible to freely adjust the positions of the cutting edges of the plurality of cutting tools in a short time. Therefore, by holding and rotating the workpiece by the rotation drive device, adjusting the cutting edge positions of the plurality of tools by the tool displacement device, and moving the plurality of tools orthogonal to the rotation axis by the moving table, Ultra-precision cutting is possible, and even if the position of the cutting edge of the cutting tool changes due to wear or the like, the position of the cutting edge can be adjusted in a short time in response to the change, and the ultra-precision cutting can be continued for a long time.

[0011]

Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing the working principle of ultra-precision cutting according to the present invention. In this figure, an ultra-precision cutting device 10 according to the present invention includes a rotary driving device 12 for holding and rotating a workpiece 5 and a bit displacement for holding a plurality of bits 14 at an interval and minutely displacing the bit position. The apparatus includes a device 20 and a moving table 16 for moving the bite displacement device 20 perpendicularly to the rotation axis of the rotary drive device 12. Each of the plurality of cutting tools 14 may be a diamond cutting tool.

The tool 20 has a plurality of cutting tools 14.
And a piezoelectric element 24 that supports the bite holding plate 22 at three points and slightly displaces the support point in parallel with the rotation axis. A voltage is applied to the piezoelectric element 24. Then, the tool holding plate 22 is minutely displaced (slightly displaced and slightly tilted in parallel with the rotation axis) so that the positions of the cutting edges of the plurality of bits can be adjusted.

With such a structure, as schematically shown in FIG. 1B, a cutting tool displacement device 20 using a piezoelectric element 24 is used.
By aligning the cutting edge positions of the cutting tools 14, the cutting positions of the three cutting tools 14 are sequentially increased, that is, the cuts are sequentially increased, so that cutting can be performed three times in one pass with a machining efficiency of three times. Becomes Also, the workpiece 5 (hereinafter, referred to as
By using a hydrostatic bearing for the rotating shaft of the workpiece (referred to as a workpiece), the rotational accuracy of the workpiece 5 can be improved, and ultra-precision cutting to obtain a mirror surface by cutting can be realized. Even if only one cutting tool 14 is used in the present working principle, the cutting tool 14 is moved by the displacement of the plurality of piezoelectric elements 24 of the cutting tool displacement device 20 (hereinafter, referred to as a displacement table).
(See FIG. 6 described later) to control and change the width and length of the cutting waste. For this reason, not only machining efficiency and surface roughness, but also machining quality and tool life can be improved.

FIG. 2 is an overall sectional view of the cutting tool displacement device 20 (displacement table). In this figure, the cutting tool displacement device 20 further includes a base 25 positioned substantially parallel to the cutting tool holding plate 22 and fixed to the moving table.
A pressurizing device 26 that urges the bite holding plate 22 toward the base side (downward in the figure), and an elastic support device that elastically holds the bite holding plate and prevents movement perpendicular to the rotation axis (horizontal movement in the figure). 27. Further, a plurality of piezoelectric elements 24
Are sandwiched between the cutting tool holding plate 22 and the base 25. Further, the bite displacement device 20 has a position sensor 28 for detecting displacement of the support point.

That is, as shown in FIG. 2, the displacement table 20 is roughly divided into a base 25 and a cutting tool holding plate 22 (hereinafter referred to as an upper plate).
The book (only one is shown in the figure) is sandwiched. Further, a preload is applied between the base 25 and the upper plate 22 by a spring 26a of a preload device 26 so that the upper plate 22 and the piezoelectric element 24 are not separated. Spring 26a
Is preferably an elastic member such as a coil spring, a disc spring, or rubber. Further, in order to clarify the relationship between the driving voltage applied to the piezoelectric element 24 and the actual displacement of the displacement table 20,
The displacement table has a built-in capacitance-type non-contact displacement sensor 28 with a resolution of 50 nm, so that the actual displacement can be measured in-process.

The elastic support device 27 comprises a flat thin plate 27a, a base casing 29, bolts 31 and the like. The periphery of the thin plate 27a is fixed to the base 25 via the base casing 29 by bolts 31.
Is fixed to the upper plate 22 by bolts 31. With this configuration, the horizontal force acting on the cutting tool can be transmitted to the base 25 as the in-plane stress of the thin plate 27a without applying a horizontal load or a tensile load to the piezoelectric element 24.

Further, in FIG. 2, reference numeral 32 denotes a tool plate to which a plurality of cutting tools are directly attached, and the tool plate 32 is fixed to the upper plate 22 by bolts or the like (not shown). Also, 33
Is an O-ring, and 34 is a cover, which seals the inside of the displacement table 20 so that hydraulic oil and water droplets do not enter inside during use.

Table 1 shows the specifications of the piezoelectric element 24 used, and the maximum displacement is about 16 μm. The piezoelectric element 24 is a solid actuator, and has characteristics such as rigidity, stability, and responsiveness that can sufficiently withstand actual cutting.

[0019]

[Table 1]

Using the ultra-precision cutting device 10 having the above-described configuration, the workpiece 5 is held and rotated and driven to
4 is supported by three piezoelectric elements 24, and a voltage is applied to the piezoelectric elements 24 to slightly displace the supporting points in parallel with the rotation axis of the workpiece 5, thereby cutting the cutting edges of the plurality of cutting tools 14. By adjusting the position and then moving the plurality of cutting tools 14 orthogonally to the rotation axis, thereby cutting the workpiece 5 with the plurality of cutting tools 14, it is possible to perform ultra-precision cutting and wear. Even if the cutting tool position changes, the position of the cutting edge can be adjusted in a short time in response to the change, so that ultra-precision cutting can be continued for a long time.

Hereinafter, test results by the apparatus and method of the present invention will be described. Table 2 shows the configuration of the ultra-precision cutting experiment system used for the test.

[0022]

[Table 2]

As shown in Table 2, a single crystal diamond was used for the tool (tool 14) to obtain a sharp cutting edge, and the shape of the cutting edge was configured as shown in FIG. 3 with reference to a milling tool. . 3A is a front view, FIG. 3B is a plan view, and FIG. 3C is a side view.
Is the processing surface (main cutting edge). The work 5 is cut by moving the cutting tool 14 in the direction of the arrow in FIG. A cemented carbide tool bit was used for rough cutting of the work.

As the processing machine, a rotary surface grinding device having an hydrostatic bearing having a rotational accuracy of 0.1 μm or less was used. The cutting resolution can be attained by 1 μm only by using the same grinding apparatus, and by using the displacement table 20, about 0.1 μm can be achieved. Rotary driving device 12
And a rotary table was used as the moving table 16. That is, the work 5 was arranged on the grindstone shaft, and the cutting tool 14 and the displacement table 20 were arranged on the rotary table.
An aluminum alloy was used for the work material (work 5). FIG. 4 shows the shape of the work.

FIG. 5 is a diagram showing the relationship between the drive voltage of the displacement table 20 and the actual displacement. The linearity was good at a driving voltage of 100 V at the maximum, and the reproducibility of the displacement was also good.
In this test, three piezoelectric elements 24 were simultaneously driven using a piezoelectric element driving power supply and a displacement measuring device (not shown). FIG. 6 is a diagram showing the positional relationship between the cutting tool 14 and the workpiece 5 based on the displacement table 20. In FIG. 6, (a) shows the attitude of the cutting tool 14 at a driving voltage of 0 V, and the sub cutting edge is positioned parallel to the work 5. (B) is drive voltage 5
0V and (c) are the positions of the cutting tool 14 at 100V, which are 0.063 ° and 0.0126 ° with the workpiece 5, respectively.
At an angle. Note that these angles can be changed by the attachment position of the cutting tool 14 to the cutting tool holding plate 22 or the relative position of the piezoelectric element to the table moving direction.

FIGS. 7A and 7B are diagrams showing a processing method and a processing route in this test, wherein FIG. 7A is a side view, and FIG.
FIG. 3 is a plan view when viewed from above. A, B, C in FIG. 7 (B)
By fixing the three diamond cutting tools 14 at the positions, the three diamond cutting tools 14 can sequentially pass and cut the lower surface of the work 5 in the order of A, B, and C. The number of the bytes 14 is not limited to three, but may be two or four or more. In addition, the attachment position of the cutting tool 14 is arranged such that the plurality of cutting tools 14 do not act on the work 5 at the same time. This arrangement is shown in FIG.
As shown in (B), it may be located at the same position as the piezoelectric element 24, or may be arranged in a row on the cutting tool holding plate 22,
Further, they may be arranged separately.

In this test, one cutting tool 14 was fixed to the center of the displacement table 20 as shown in FIG. In this test, the diamond cutting tool 14 is placed on a rotary table (moving table 16), and the center path of the displacement table 20 has a radius of 175 m from the center of rotation of the table.
m. Therefore, the feed speed is the peripheral speed at the center of the displacement table, and is 50 to 100 mm / min (33 to 67 μm).
m / rev). The work rotation speed is 1500 rpm
m (cutting speed v297 to 509 m / min), and the cutting depth was 2 to 10 μm / pass.

In the apparatus shown in FIG. 7, first, a basic experiment for transferring the cutting edge shape of the single crystal diamond tool 14 to the work 5 was performed, and the work 5 was cut and transferred to the tool 14 while supplying cutting oil in the form of a mist. . FIG. 8 is a cross-sectional pattern showing the cutting edge transfer of one cutting tool obtained by the basic test. It can be seen from this figure that the shape of the cutting edge is roughly transferred. However, it was considered that the blade surface did not hit the work surface in parallel due to the mounting accuracy of the upper surface of the displacement table.
While rotating the cutting tool 6, the blade surface of the diamond cutting tool 14 was inclined by the displacement table 20 as shown in FIG.

FIG. 9 shows the obtained cut surface roughness. As apparent from FIG. 9, R _max 60nm, specular good before and after R _a 13 nm was obtained. At this time, the inclination of the cutting tool was given in such a state that a voltage of 100 V was applied to two of the three piezoelectric elements and a displacement of about 12.5 μm was obtained.

As described above, according to the apparatus and method of the present invention, the bite displacement device 20 supports the bite holding plate 22 for holding the plurality of bits 14 and the bite holding plate 22 at three points. And the piezoelectric element 24, which slightly displaces the support point in parallel with the rotation axis, so that the support point is minutely displaced in parallel with the rotation axis of the workpiece 5 by the piezoelectric element 24, whereby the cutting tool holding plate 22 is moved in parallel with the rotation axis. Parallel minute displacement and minute tilt can be performed, and the cutting edge positions of the plurality of cutting tools can be freely adjusted in a short time. Accordingly, the workpiece 5 is held and rotated by the rotation drive device 12,
By adjusting the positions of the cutting edges of the plurality of cutting tools by the cutting tool displacing device 20 and moving the plurality of cutting tools orthogonally to the rotation axis by the moving table 16, ultra-precision cutting is possible, and the cutting tool position due to wear or the like is possible. Therefore, the position of the cutting edge can be adjusted in a short time in response to the change, so that ultra-precision cutting can be continued for a long time.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

[0032]

As described above, the ultra-precision cutting device and method using piezoelectric position control according to the present invention has a plurality of cutting tools, and the cutting edge positions of the plurality of cutting tools can be freely adjusted in a short time. Therefore, even if the cutting edge position changes due to wear, etc., the cutting edge position is adjusted in a short time in response to this, so that ultra-precision cutting can be continued for a long time and ultra-precision cutting can be performed more efficiently than conventional methods , Etc. have excellent effects.

[Brief description of the drawings]

FIG. 1 is a view showing a processing principle of ultra-precision cutting according to the present invention.

FIG. 2 is an overall sectional view of a cutting tool displacement device (displacement table).

FIG. 3 is a diagram showing a cutting edge shape of a cutting tool.

FIG. 4 is a diagram showing a work shape.

FIG. 5 is a diagram illustrating a relationship between a driving voltage of a displacement table and an actual displacement.

FIG. 6 is a diagram showing a positional relationship between a cutting tool and a workpiece by a displacement table.

FIG. 7 is a diagram showing a processing method and a processing path in a test.

FIG. 8 is a cross-sectional shape pattern showing the transfer of the cutting edge of one cutting tool.

FIG. 9 is a view showing a cut surface roughness obtained by a test.

FIG. 10 is a view schematically showing a conventional processing method.

[Explanation of symbols]

 1 byte 2 fly cut tool 3 polygon mirror 5 workpiece (work) 10 ultra-precision cutting device 12 rotation drive device 14 byte 16 moving table (rotary table) 20 byte displacement device (displacement table) 22 byte holding plate (upper plate) 24 Piezoelectric element 25 Base 26 Preload device 26a Spring 27 Elastic support device 28 Displacement sensor

Claims (4)

[Claims] 1. A rotary drive device for holding and rotating a workpiece, a bit displacement device for holding a plurality of bits at an interval and minutely displacing the bit position, and a rotary drive device for rotating the bit position device. A moving table that moves orthogonally to a rotation axis; the bite displacement device includes a bite holding plate that holds a plurality of bits; and the bite holding plate is supported at three points, and the support point is parallel to the rotation axis. A micro-displaced piezoelectric element, and applying a voltage to the piezoelectric element to finely displace the bite holding plate to adjust the positions of the cutting edges of the plural bits, thereby cutting the workpiece with the plural bits. An ultra-precision cutting device using piezoelectric position control. 2. The tool according to claim 1, further comprising: a base positioned substantially parallel to the tool holding plate and fixed to the moving table; a pressurizing device for urging the tool holding plate toward the base; 2. The piezoelectric device according to claim 1, further comprising: an elastic supporting device that holds the piezoelectric element and prevents movement perpendicular to the rotation axis, wherein the piezoelectric element is sandwiched between a cutting tool holding plate and a base. Ultra-precision cutting device with position control. 3. The cutting machine according to claim 1, wherein the cutting tool further includes a position sensor for detecting a displacement of the support point. 4. A workpiece holding and rotating drive is performed, a tool holding plate for holding a plurality of tools is supported by three piezoelectric elements, and a voltage is applied to the piezoelectric elements to rotate a support point of the workpiece. Adjusting the positions of the cutting edges of the plurality of tools by making a small displacement parallel to the axis, and then moving the plurality of tools orthogonally to the rotation axis, thereby cutting the workpiece with the plurality of tools. Ultra-precision cutting method by piezoelectric position control.