JPH028856B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a precision cutting system, and more particularly to a novel cutting system capable of finishing a quadratic curved surface such as a spherical or aspherical surface into a mirror surface using a diamond tool or the like.

1960-1970 in the field of precision cutting technology
In the 1990s, processing machines with a processing accuracy of 1 micron were researched and developed. Then, in the 1970s, processing machines aimed at submicron (0.1 micron) became required in fields such as semiconductors and space rockets, and in the 1980s, laser technology
Inspired by VLSI technology, processing machines with processing accuracy of 0.1 micron or less have become required.

However, the above-mentioned mirror finishing technology of about 0.1 micron has been mainly performed by grinding, and the target of these mirror finishing processes is simply a flat surface or a circumference obtained by grinding the outer periphery of a bar. The technical challenge of mirror-finishing quadratic surfaces (paraboloids, hyperboloids), etc., which is limited to surfaces, and achieving this through cutting has not been possible with conventional processing machines. It's almost impossible.

The reason for this is that apart from the socio-economic point that the demand and request for mirror finishing processing of quadratic curved surfaces etc. was extremely limited, from a purely technical point of view, the machines that make up the processing machine The influence of component temperature on machining accuracy and the influence of the feed drive system on the tool (for example, the accuracy of the guide surface, the resolution of the drive motor itself, the accuracy of the feed screw, the accuracy of the position feedback detector, and the response of the drive system) (Contains various error factors in terms of quality, etc.)
There are problems such as.

In particular, the latter problem is that while the aforementioned plane or circumferential grinding process basically targets the control of relative movement between the tool (grinding wheel) and the workpiece in a uniaxial direction, for example, when grinding a quadratic curved surface, At the same time, feed control is required in two axial directions, and when this is combined with the currently required high precision of the machined surface, this involves complex unresolved technical problems.

For example, currently, simultaneous two-axis (x, y) feed drive control itself does not take into account the machining accuracy.
Naturally, this has already been realized using NC machine tools.

However, with NC machine tools, the accuracy of detecting the amount of movement of tables, etc. is at most 1 micron, and even with specially manufactured tools it is about ±0.5 micron.

Furthermore, regarding the NC device itself, if the minimum resolution command value is 0.01 (micron/pulse) and the maximum cutting feed rate is 600 mm/min, it will be 600 x 10 ³ /60 [micron/sec] x 1/0.01 [pulse/micron]. ] = 1MHz, and the pulse distribution speed is required to be high, so
There are circumstances that make it difficult to perform interpolation calculations within the NC device.

In addition, the position detector for feedback can measure a certain amount of movement, and is 0.01 μm.
At present, only a laser length measuring device is available with a certain degree of accuracy, and simply incorporating a laser length measuring device leaves the problem that the drive system cannot respond to the error signal obtained.

The present invention aims to go beyond the current state of the art, and its purpose is to control the relative position between a tool and a workpiece with an accuracy of about 1μ or ±0.5μ. A precise position measurement system such as a laser interferometer is further installed in the drive control system to measure the actual position of the tool tip, and calculations are made based on this measurement data and the measurement data in advance or at that time. By providing the difference between the theoretical value data (theoretical position data of the tool tip to form the desired machined surface) using a micro-displacement drive system with good sequential response characteristics, the The aim is to bring the tip position of the tool as close to the theoretical value as possible.

Still another object of the present invention is to realize the minute displacement drive system using piezoelectric effects and magnetostrictive effects. This is because such electromagnetic elements perform minute displacement operations with relatively good responsiveness to electrical commands.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the general configuration of a system according to the present invention. In the figure, 11 indicates a drive control system that provides relative movement between the cutting tool T attached to the cutting machine 12 and the workpiece W, and 11-1 indicates each drive necessary for the relative movement. This is an axial movement command section that gives commands in the axial direction, and this command section may be constituted by a numerical control device of a machine tool, or may be a control device using a "servo system" to be described later. In the following explanation, in order to facilitate understanding, the drive axis direction is a Cartesian coordinate system (orthogonal coordinate axis), and two axis directions, X and Y, will be explained as an example.

In the case of a numerical control device, the amounts to be moved in the X and Y directions are output from the command unit 11-1 at regular intervals as ΔX and ΔY, respectively, and are given to the drive unit 11-2. Also, in the case of the control device configured by the servo system, ΔX and ΔY are given, but in this case, ΔY depends on ΣΔX and the control device (11-1)
It is assumed that the calculation is made within

The drive unit 11-2 receives input command data ΔX,
It shows a part that accepts ΔY and drives a servo motor for driving the X and Y axes, and shows a servo amplifier for each axis, a servo motor, a ball screw connected to the output shaft of the motor, and a numerical control device 11-1.
It has come to include equipment (for example, a rotary encoder or a resolver) that generates position feedback signals ΔXF and ΔYF.

12 is a cutting machine, and the figure shows an example in which the workpiece W does not move in the X and Y axes and the tool support TS is driven in the X and Y axes by a drive unit 11-2. However, it may be configured in the opposite way.

13 is a correction system provided corresponding to the drive command section 11-1 and the drive section 11-2. The correction system 13 is provided with a precision measuring section 13-1 that precisely measures the amount of axial movement of the cutting tool T or its tool rest TS, and this measuring section 13-1 is constructed using, for example, a laser interferometer. Reference numeral 13-1A denotes an interferometer regarding the Y axis, and its output y represents the amount of displacement of the mirror MRy attached to the tool rest TS from a certain reference position _y0 . Reference numeral 13-1B indicates a laser interferometer regarding the X axis, and its output x represents the amount of displacement of the mirror MRx attached to the tool rest TS from a certain reference position _x0 . Note 13-1A, 13
The arrow between -1B indicates correction of the installation error of the mirrors MRy and MRx and the error of the mirror itself. 13-
2 is the current value data x in the X-axis direction given from the precision measurement section 13-1, that is, the tool T or the tool post
A theoretical value data supply unit that provides a theoretical Y-axis direction position y _t (=f(x)) corresponding to the X-axis direction position of the TS, which is a specific determined X-axis direction position.
Theoretical values f (x ₀ ), f corresponding to x ₀ , x ₁ , x ₂ , x ₃ ...
(x ₁ ), f(x ₂ ), ... may be calculated in advance, or when the values x ₀ , x ₁ , x ₂ ... are given, high-speed calculations can be performed using a computer, etc. Then f(x ₀ ), f
(x ₁ ), f(x ₂ )... may be calculated each time. And these theoretical value data f(xj)
It is necessary to calculate the effective digits of at least the same number as one output y of the precision measuring section 13-1.

13-3 is an arithmetic unit that calculates the difference between the Y-axis direction position y and data f(x) given correspondingly; 13-4 is a calculation unit that calculates the Y of the tool T based on this difference;
Correct the position in the direction by a minute amount δy and calculate y and f(x)
This is a micro-displacement drive unit that slightly displaces the turret TS so that the

Reference numeral 13-5 designates a coefficient α for the output of the arithmetic unit 13-3, which specifies the correction amount δy and the difference f.
This is provided to maintain an appropriate relationship between (x) and y. It is possible to use a piezoelectric effect, a magnetostrictive effect, etc. as the minute displacement drive section 13-4.

FIG. 2 is a plan view showing the arrangement of a cutting machine and a laser interferometer in an embodiment of the present invention, and FIG. 3 is a view taken along the Z arrow in FIG.

In FIGS. 2 and 3, a saddle 22 is mounted on the bed 21 so as to be movable in the X direction.
A movable table 23 is further mounted on 2 so as to be movable in the Y direction. The saddle 22 can be moved in the X direction by the X-axis drive motor 24 and feed screw 24A. Similarly, the movable table 23 can be moved in the Y direction by the Y-axis drive motor 25 and feed screw 25A. 24B,
25B indicates a resolver for position feedback. A tool mounting base 31 is fixedly provided on the moving base 23, and a minute displacement drive unit 32 is mounted on the right side of the tool mounting base 31.
A tool holder 33 having a tool T fixed thereto is further provided at the right end of the drive section 32. In other words, by exciting the drive section 32, the tool T can be displaced by a minute amount with respect to the mounting base 31 in the Y direction together with the holding section 33. Furthermore, a plane mirror MRx for measuring the position of the moving table 23 in the X-axis direction is attached to the upper surface of the moving table 23, and a mirror for measuring the position of the moving table 23 in the Y-axis direction is attached to the mounting table 31. A spindle unit 41 with a workpiece W attached to its tip is mounted and fixed on the upper right side of the bed 21, and a pulley 42 of the unit 41 is mounted and fixed.
The rotation of the drive motor 44 is transmitted through a timing belt 43 and a pulley 45 on the shaft of the motor 44. In order to minimize the vibrations caused by the rotation of the motor 45, it is necessary to take sufficient anti-vibration measures.

On the other hand, the laser beam is emitted from the laser beam oscillator LG, passes through the semi-transparent mirror MR1 and the interferometer INFX, and the reflected light from the mirror MRx is input to the interferometer INFX. It is now possible to measure the amount of movement.

In the Y-axis direction, the light is deflected at right angles by semi-transparent mirror MR1, further deflected at right angles by mirrors MR2 and MR3 as shown in the figure, passes through laser interferometer unit INFY for Y-axis, and is reflected from mirror MRy. The same INFY is now receiving the same INFY.

In the processing machine shown in FIGS. 2 and 3, the precision of the guide surfaces for the movement of the saddle 22 and the moving table 23 in the X and Y axes must be maintained at high precision by using, for example, hydrostatic bearings. Regarding the accuracy of each guide surface, we have already measured the error in advance and stored it in memory. For example, when moving the saddle, we read the error data from the memory to cancel the error and use it as a movement command. additions are being made. However, it goes without saying that such correction is based on the premise that the relationship between the error value and the X-axis position is reproducible. In the above example, the error value was corrected on the same coordinate axis as the direction of movement X of the saddle, but of course this also applies even when the axial direction of the error to be corrected and the direction of movement of the saddle are perpendicular to each other.

FIG. 4 shows an example in which the mirror MRy for detecting the position in the Y-axis direction is attached to the side closer to the cutting tool T than the minute displacement drive section 32 in FIG.

In the embodiment shown in FIG. 4, more accurate y information can be received than in the case shown in FIG. 3, but some conditions are added to the mounting of the mirror MRy.

FIG. 5A shows an example of the coupling relationship between the minute displacement drive section 32, the tool mount 33, and the cutting tool T installed on the movable table 23. Figure B is a view taken along arrow V in figure A.

In FIG. 1A, the tool mount 33 is supported by a support member 51 having a hydrostatic bearing inside thereof, and is movable only in the Y direction. A minute displacement drive section 32 is disposed between the right end flange portion 33A of the tool mount 33 and the left side surface of the other mount 52, and conical projections are formed at both ends of the drive section. 33A, the tension springs 53 and 54 are inserted into the conical holes carved on the left side of the mounting base 52, respectively.
These act to draw the tool mount 33 to the right, so that the conical hole and the protrusion are in close contact with each other.

The main body 32 surrounded by the broken line of the drive section 32
A piezoelectric element is incorporated in A, and an arbitrary DC voltage of about 1000 volts at maximum is supplied from a variable DC voltage power supply 55. When an electric field (VOlt) is applied in the thickness direction to a piezoelectric element having a thickness of l, commercially available piezoelectric elements will expand by Δl. Its characteristic equation is approximately given by Δl/l=0.5×10 ^-6 [1/V·mm]. That is, if l = 1 mm and an electric field of K = 1000 (Volt) is applied to both ends, Δl = 0.5 x 10 ^-6 x 1000 x l = 0.5 x 10 ^-3 [mm] = 0.5 micron.

FIG. 6 shows another embodiment, in which A is a plan view, B is a side view, and C is a sectional view taken along the line I in FIG. The mounting base TS is shown in A, B, and C in the same figure.
A vertically extending support 62 is provided at the right end of the
One end of the micro-displacement drive unit 64 is fixed to the side surface of the support, and the other end (left end) is attached to the mounting base TS.
Static pressure bearing portions 63-1 (X-axis direction) and 63-2 (vertical direction) formed on the side surface of the corner portion 63 provided above
The tool mount 61 is supported statically by the tool holder 61 and fixed to the right end surface of the tool mount 61.

Therefore, the position of the tool mount 61 in the Y-axis direction is regulated by the minute displacement drive section 64. As shown in part W in the figure, the boundary surface in the X-axis direction of the corner portion 63 may have a static pressure bearing surface, but the air pressure supplied thereto is a large load against the expansion and contraction of the minute displacement drive portion 64. Consideration will be given to ensure that this does not occur.

FIG. 7 shows yet another embodiment. In the same figure, there is a knife edge 71-
1 is formed, and the edge 71-1 is fitted into a V-shaped groove 73 at the lower left end of the mounting base 72. Furthermore, the tool holder 71 has a compression spring 75 moored under the head and neck of a bolt 74 screwed onto the mounting base 72.
It is constantly being pulled to the right.

Further, a bolt 76 is inserted into the holding body 71 from below.
is screwed onto the mounting base 72 and is constantly drawn downward toward the mounting base 72 by a compression spring 77 as shown in the figure. On the other hand, on the upper surface of the mounting base 72 is a minute displacement drive unit 80 whose right end is fixed with a bolt 79.
A steel ball 81 is arranged at the left tip of the drive unit 80.
is attached and in contact with the tool holder 71.

Therefore, the tool T fixed to the holder 71 by the bolt 71-2 can swing about the knife edge 71-1 as a fulcrum by exciting the minute displacement drive section 80, and as a result, the tool T can be swung around the knife edge 71-1 as a fulcrum.
It is possible to make a small amount of displacement in the direction. At this time, the amount of displacement in the vertical direction does not pose a problem since the amount of displacement in the Y direction is small.

Figure B shows a plan view of Figure A, Figure C shows a front view, and Figure D shows a sectional view taken along the line -- of Figure A. In addition, in order to improve the response to minute displacements of the tool T, the holder 7
1 and the characteristics of the compression springs 75 and 77 should be taken into consideration. In addition to the above-mentioned example, for example, a method may be used in which the driving portion 32A is fixed between the members 33A and 52 as shown in FIG. FIG. 8 shows an example in which a minute displacement is applied to the workpiece in a machining method in which the workpiece W is fixed and the tool T is rotated to perform cutting. This figure corresponds to the case where the tool holder 33 and the workpiece W in FIG. 4 have been replaced.

FIG. 9 is a diagram showing the configuration of a minute displacement drive unit using piezoelectric elements. In the figure, piezoelectric elements 91, 92, and 93 of length l are arranged in series, and electrodes are provided between each element and at both ends. Silver foils 94 to 97 are interposed. 98 and 99 are insulators, 100 and 101 are coupling members, and 102 is a support body. And silver foil 9
5 and 97 are grounded, and silver foils 94 and 96 are connected to the high voltage side of the variable DC power supply 103.

FIG. 4B shows the relationship between the voltage K applied to both ends of one piezoelectric element 91 having a length l and the elongation Δl.

When l=1mm and K=1000 volts, Δl=0.0005mm
When K=3000 or more, it becomes saturated.

Considering the height of the supply voltage, for example, K=about 500 volts can give an elongation of about 0.25 microns. By setting K±ΔK=500±300 (Volt), a change of ±300 volts can cause a displacement of ±0.15 microns, resulting in +0.1~
A minute displacement of +0.4 (μ) can be generated. In Figure A, three piezoelectric elements are arranged in series, so 0.1×3 to 0.4×3 => 0.3μ to 1.2μ, and adjustment can be made within a range of ±0.45μ with 0.75μ as the center. This adjustment is possible by changing the DC voltage K.

FIG. 10 shows a control system for the micro-displacement drive unit using a numerical control device in the machining system according to the present invention. In the figure, the cutting tool T moves the surface of the rotating workpiece W toward +X by P2 from
While moving to P3, the desired shape is processed by cutting in the Y direction. Although the figure shows an example in which the workpiece W is machined in a convex shape, it goes without saying that the machined surface may be concave.
Now, from the laser interferometer 110, X by the laser,
The measurement pulses LPX, LPY (given every 0.01 micron) in the Y-axis direction are sent to the laser counters 111, 1.
12 shall be given. On the other hand, 121 is the machining origin P2 of the desired curved surface in machining the workpiece W.
This is the machining origin setting section that sets (XWO, YWO).

The counters 111 and 112 are reset when the moving body 23 in FIG. 2 is positioned at the origin P1 (XO, YO) specific to the processing machine. Point P
1 to point P2. This movement path may be straight lines P1 and P2, but considering that the trajectory of the tip of the tool T enters cutting of the machining curved surface SF from point P2, when it approaches point P2, it will move in the tangential direction at point P2. It is best to make it so that Tool T mounted on the moving table 23 to point P2
When the tip of
GX and GY allow pulses LPX and XPY to pass through.

The numerical control device 122 responds to the signals CX and CY after receiving the command for preliminary movement from point P1 to P2 to issue a command for simultaneous two-axis control regarding the X and Y axes for the machining curved surface SF. Servo out outputs ΔX and ΔY are applied to servo units 123 and 124, respectively, at each sampling time, thereby causing X-axis servo motor 125 and Y-axis servo motor 126 to rotate. As a result, the moving table 23 moves the tip of the tool T so that it follows a trajectory that approximates the curved surface SF.

Further, position feedback pulses FBPX and FBPY regarding the X and Y axes are applied to the numerical control device 122.

For these values of servo out ΔX and ΔY from the numerical control device 122, the tip of the tool T has a speed error of F/ωc inherent to the drive control system (F is the feed rate and ωc is the loop gain of the drive system). Moreover, the accuracy of the detection position is usually about 0.5 to 1 micron. Since we are now attempting to cut the workpiece W into a machining curved surface of 0.1 micron or less, there will be a difference between the theoretical position on the curved surface and the actual tool tip position. In order to minimize this difference, the correction system 13 shown in FIG. 1 is used. This correction system uses counters 131 and 1 to measure the position of the tool T in the X-axis direction and the Y-axis direction from point P2 during cutting.
32 for accurate counting and a counter 13 in the X-axis direction.
The theoretical value in the Y-axis direction corresponding to the value of 1 is read out from the memory M as F(xk), the difference from the measured position in the Y-axis direction is calculated by the calculation unit 135, and this is provided to the conversion unit 138. Y via the power converter 139
This is done by applying a minute displacement in the axial direction to the driving section 140. As can be seen from FIG. 2, this drive by the drive unit 140 is performed on the movable table 23.

136, 137, and 136A form a generation unit for the coincidence signal COiN, and after determining the amount of movement x (N) in the X-axis direction in advance, the number N of laser counting pulses LPX is set in the setting unit 136A. It's becoming like that. 136 is a counter into which the pulse LPX is input.

137 is a comparator, and when the contents of the counter 136 match N, the coincidence signal COiN is generated and the counter 136 is cleared. This match signal
COiN is emitted every time the moving table 23, and thus the tool T, moves x(N), that is, N×0.01 micron. Then, the value of the counter 132 is set in the register 133 by this signal COiN, and is also memory-outed from the memory M to the buffer register 134.

Further, this signal COiN is provided as a counting input to an address counter 144 for the memory M.

As shown in the figure, in the memory M, addresses (ADRS) and data (DATA) are shown as a pair, and each address 0, 1, 2, 3, ... is located every 0.01 x N microns from point P2 in the X-axis direction. corresponds to the location
x0, x1, x2, ... indicate those values. (However, x0
= 0) In this example, the memory M is RAM (Random Access
A computer that instantaneously calculates F(xk) from the contents of the counter 131 shown as ROM (Read Only Memory) or ROM (Read Only Memory) may be used instead.

Also, for the memory M, RAM and ROM are used, but since the theoretical values are used sequentially, the data F(x0), F(x1),
...F(xn) may be calculated and three or five of these may be sequentially taken into the buffer. In this case, the buffer has an intermediate buffer in addition to the final one (134).

Furthermore, in the example of memory M in FIG. 10, F(x)
The data itself was theoretical value data with approximately the same number of effective digits as the value of the Y-axis laser counter 132, but from the perspective of saving memory capacity, F(xi) was increased with respect to F(xi-1). It is also possible to store only the amount or decrease amount in the memory as a value ΔF(xi) corresponding to xi. In such a system, F(xk) is given as F(xk)=F(x0)+ _k 〓 ^k=1 ΔF(xk). Therefore the first value F(xo)
need to be given.

Reference numerals 141 and 142 indicate correction means for correcting the contents of the counters 132 and 131. Such a correction means is, for example, a laser mirror MRx shown in FIG.
When the value of The content of the document is modified. Similarly, the correction means 141 corrects the contents of the counter 132 when the value of Y changes as Δy(Xi) with respect to the movement of the laser mirror MRy only in the X-axis direction, so as to cancel this change.

The signal E is a signal line that informs the numerical control device 122 of the contents of the counter 131.
2 determines that the tool T has reached a point P3, that is, the machining end position, and retracts the tool T.

FIG. 11 shows a control system using a servo system instead of a numerical control device. In this figure, the same symbols and numbers used in FIG. 10 indicate the same components.

In this servo system, the moving speed of the moving table 23 (tool T) in the X-axis direction is set to a constant value. This speed is set by the X-axis direction speed setting section 121-1 in the setting section 121, and its output Vx is
The signal is applied to the X-axis drive servo motor 125 via a converter 151 and a servo amplifier 152.

The part surrounded by a broken line in the center of the figure shows the drive control system CTRL of the moving table 23 in the Y-axis direction, and the control system CTRL receives a laser pulse in the X-axis direction.
The output of a counter 131 that counts LPX is given. Further, 153 is a timing pulse SP1, SP2, . . . for calculation at every fixed sampling time SP.
...This is a pulse generator that generates SP5, and takes in the contents of the counter 131 to the register 154 at the first timing SP1. At the same time, register 155
The contents of the counter 132 for the Y-axis direction are taken in. (Note that the register 154 does not necessarily need to capture all valid digits of the counter 131.) At the next timing step SP2, based on the contents x of the register 154, the arithmetic unit 156
(x) is calculated.

This function f(x) does not necessarily have to match the function F(x) for calculating the theoretical value given from the memory M, but is approximately determined in consideration of the accuracy and responsiveness of the X and Y axis drive system. be able to. At step SP3, the calculation result (calculated value) at step SP2 is stored in the register 157.

Next, in step SP4, the difference calculation unit 158
calculates the difference between the contents of registers 155 and 157. The result is stored in register 159 at step SP5. The value of the register 159 is given to the Y-axis drive servo motor 126 via a D/A converter 160 and a servo amplifier 161.

On the other hand, the coincidence signal COiN is also input to the register 155, and the contents of the register 155 are given to the calculation unit 135 at this timing (COiN), and the difference with the contents of the buffer register 134 is given to the conversion unit 138. Power converter 139
The minute displacement drive section 140 is driven through the micro displacement drive section 140.

Regarding the register 155, since there is no direct relationship between the timing at which the signal COiN is issued and the timing at which SP1 is issued, another register (not shown) is provided to capture the value of the counter 132 when the coincidence signal COiN is issued. In this way, the value of this other register may be input to the arithmetic unit 135. The control systems described above in FIGS. 10 and 11 each have a minute displacement drive section 140 in the Y-axis direction, and the signal for driving this is a combination of the theoretical value F(x) and y obtained from the laser system. What they have in common is that they try to gain from the differences.

Modifications of the above embodiments will be described below.

In the examples shown in FIGS. 2 to 8, the minute displacement drive sections are all arranged between the cutting tool T and the moving table 23, and this is partly due to the load portion for the drive sections. This is intended to prevent a decrease in responsiveness, but if a certain level of responsiveness can be ensured in this respect, the distance between the movable base 23 and the feed screw 25A, for example, the lower surface of the movable base 23 in FIG. A minute displacement driving section may be provided between the moving table 23 and the nut screwed into the feed screw 25A.

Furthermore, in the example shown in FIG. 9, piezoelectric elements 91, 92, 93 are replaced with silver foils 94, 95, 9
6 and 97, however, it may be constructed using only an integrated piezoelectric element if the necessary amount of displacement can be obtained. In addition, in the embodiments of the present invention (Figs. 10 and 11), xi-xi-1 was set to a constant value (0.01 x N microns), but it is possible to make this N variable, so that the correction operation can be performed in the X-axis direction. It is also possible to not limit the positions to just regular intervals.

To do this, the values of x1, x2, . . . , xi, . Bye.

Furthermore, if the characteristic of the displacement .DELTA.l with respect to the voltage K in FIG. 9(b) is not a perfect linear portion, the designation section 13-5 of FIG. 1 corrects .alpha. as described above. Further, if the characteristic has hysteresis, the hysteresis characteristic regarding f(x)-y is stored in advance, and the specification unit 13
-5 may be output by considering its hysteresis characteristics when outputting α.

As explained above, in the present invention, when the cutting tool and the workpiece move relative to each other, a correction system is provided which applies a minute displacement in the cutting direction of the tool using a relatively responsive drive means, and precision measurement is performed. Since the amount to be corrected (in the cutting direction) given from the system and theoretical value data is quickly corrected, the trajectory of the cutting tool on the workpiece surface is formed almost exactly as the theoretical value. This has the effect of making it possible.

Therefore, in processing a Schmitt lens, for example, a curved surface conforming to the theoretical value is formed, so that an optical system using the same lens can be made simpler than before.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a system according to the invention;
Fig. 2 is a plan view of a processing machine according to an embodiment of the present invention, Fig. 3 is a view taken in the direction of the Z arrow in Fig. 2, and Fig. 4 shows a mounting position of the laser mirror in the Y-axis direction closer to the cutting tool than in Fig. 3. Fig. 5A is a plan view of one embodiment of the micro-displacement drive mechanism, Fig. 5B is a view taken from arrow V in Fig. 5A, and Fig. 6 is a micro-displacement drive using a hydrostatic bearing. Fig. 7 shows another example of a minute displacement drive part having a knife edge support mechanism. In the figure shown, figure A is a detailed sectional view of the main part, figure B is a plan view, figure C is a front view,
Figure 8 is a cross-sectional view taken along the - line in figure A, Figure 8 is a diagram showing an example of a processing machine in which a workpiece is fixedly connected to a minute displacement drive unit to rotate a cutting tool, Figure 9
Figure A is a diagram showing an example of configuring a micro-displacement drive unit using a piezoelectric element, Figure B is a graph showing the voltage and elongation characteristics of one piezoelectric element, and Figure 10 is a diagram showing this machining system using a numerical control method. Detailed block diagram of the system when implemented. FIG. 11 is a detailed block diagram of the system when implemented using the servo method. 11... Drive control system, 11-1... Axis movement command section,
11-2...Drive unit, 12...Cutting machine, 13...
Correction system, 13-1... Precision measurement section, 13-2... Theoretical value data supply section, 13-3... Calculation section, 13-4...
minute displacement drive section, 21...bed, 22...saddle,
23...Moving table, 24...X-axis drive motor, 25...Y
Shaft drive motor, 24A, 25A...Feed screw, 24
B, 25B...Resolver, 31...Tool mounting stand, 41
...Spindle unit, 42...Pulley, 43...Timing belt, 44...Drive motor.

Claims (1)

[Scope of Claims] 1. A cutting system that forms a desired machined surface on the workpiece by relatively moving a workpiece and a cutting tool, comprising: forming a machined surface that approximates the desired machined surface on the workpiece; a drive control system that relatively moves the tool post that supports the cutting tool and the workpiece for cutting; and a positional accuracy of the drive control system that determines coordinate values representative of the tool tip while the drive control system is driving. a precision measurement system for measuring with higher accuracy; and a theoretical value data supply means for supplying theoretical value data regarding coordinate values in the cutting direction of the tool in response to data in one coordinate axis direction obtained from the precision measurement system. , minute displacement drive means for minutely displacing the tool in the cutting direction on the tool post based on the difference between the value of the tool cutting direction coordinate axis obtained from the precision measurement system and the output of the theoretical value data supply means; A precision cutting system characterized by: 2. The precision cutting system according to claim 1, wherein a laser interferometer is used as the precision measurement system. 3. The precision cutting system according to claim 1, wherein an electromagnetic displacement element is used as the minute displacement driving means. 4. Precision cutting according to claim 1, characterized in that the theoretical value data supplying means includes a memory that stores in advance theoretical value data for position data in the one coordinate axis direction in pairs. system. 5. The theoretical value data supplying means includes a calculation unit that calculates theoretical value data in the cutting direction corresponding to the position data in the one coordinate axis direction each time. Precision cutting system as described in Scope 1. 6. The precision cutting system according to claim 1, wherein the drive control system includes a numerical control device. 7. The precision cutting system according to claim 1, wherein the drive control system is constructed using a servo system.