JPS5890441A - Precision machining system - Google Patents

Abstract

PURPOSE:To compensate a difference from the theoretical value by a drive part, by furnishing a tool holder, sliding in the Y direction driven by a micro-displacement drive part, on a tool rest, and by measuring the position of the tool holder with an optical measuring instrument. CONSTITUTION:The X and Y positions of a tool holder 4 are measured by laser measuring instruments 12, 13, and the output pulses therefrom are counted by counters 14, 20. The calculated value X of the X-axis counter 14 is fed into an operator circuit 15, and the theoretical position on the Y axis corresponding to the X-axis position is calculated according to the desired curvature to be machined. The output value y with the Y-axis counter 20 is compared with the theoretical value Y of the operator circuit 15 to control a micro-displacement element 6. The counted value y held at a holder circuit 21 is compared with the theoretical value Y by the comparator 20, and every difference exceeding a specific value DELTAy is fed into an additive register 19 to give a drive signal DELTAY for driving a certain distance, and thus tool rest 5 is driven for DELTAY step by step. Accordingly the micro-displacement element can be always held in work within a proper range.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a precision cutting system for finishing an axially symmetrical quadratic curved surface into a square shape.

Recently, in the field of NvM processing, laser technology, ultra-L 81
Due to the influence of Vt @ temple, processing machines for processing n1 of 0.1 micron or more are being used. However, conventional machining machines with a machining degree of 0.1 μm or more are mostly grinding processes, and the machining target is a simple flat surface or a circumferential direction, which is best achieved by grinding the outer periphery of a rod-shaped member. was limited to. For this reason, it is possible to machine paraboloids, hyperboloids, etc. to a g-plane finish, and the technical challenge of doing so by cutting has not been possible with conventional processing machines.

The reason for this is that the demand for custom-finishing quadratic curved surfaces is limited! # Aside from the circumstances, from a purely technical perspective, the model number depends on the machining accuracy of the mechanical parts of the processing machine, and the machining accuracy of the feed drive system for the tool, such as the guide surface tank. The resolution of the motor itself, the precision of the feed screw, the accuracy of the position feedback detector,
Alternatively, error factors such as drive system responsiveness may be considered.

On the other hand, while the latter machining process targets the aforementioned horizontal and circumferential surfaces, cutting processing that targets secondary @planes requires control in two axial directions at the same time.

Conventionally, feed drive control that performs two-axis (X, Y) control simultaneously has been actually carried out by a 11Nc' machine tool, if machining accuracy is not considered. However, with NC machine tools, the accuracy of detecting the amount of movement of mining tables, etc. is 1.
Even if it is a special one, it is about ±0.5 micron.

Furthermore, regarding the IC machine tool itself, if the small resolution command value is set to 0.01 (microns/pulse) and the maximum cutting feed speed is 600111/min, the number of pulses is ! The speed is 41! It is also necessary to perform interpolation calculations on NC' machine tools for the required rounding.

Furthermore, the only position detector that can perform feedback control is a laser length measuring device that can measure the amount of movement with a certain degree of precision, and that can achieve an accuracy of about 0.01 microns. Even if a laser length measuring device is used, there is a problem in that the drive system cannot respond to a neglected error signal.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a training cutting system capable of cutting a quadratic curved surface with a processing accuracy of 0.1 micron or more. .

The present invention provides a tool post which is driven by an X-axis drive system and a Y@drive system to a desired position on the XY plane, and which uses a micro-displacement drive unit to position the tool post along the Y-axis at high speed and with high precision. A tool holder is provided to hold the tool holder, and the position of the tool holder is measured optically (using an IJ measuring instrument), and the difference between this sub-length value and the theoretical value is compensated for by the minute displacement drive part, and this The present invention is characterized in that each time the amount of compensation in the minute displacement drive section exceeds a predetermined set value, the Y441 sea bream driving system is driven to bring the amount of compensation within a predetermined value.

The following is the fruit of this invention! The M example will be explained in detail with reference to the block diagram shown in FIG. In the figure, 1 is the cutting tool and the rotating shaft 2
Cutting is carried out by contacting the workpiece 3 which is held and rotationally driven. The cutting tool ^1 is then driven to move relative to the workpiece 3 to cut the surface into a desired shape. In the following explanation, the driving direction of the cutting tool 1 is a straight line consisting of a Y axis parallel to the rotation axis 2 and an X axis perpendicular to the rotation axis 2. Let it be a coordinate system. The cutting tool 1 is held in a tool holder 4, and the tool holder 4 is held in a tool post 5 via a small displacement resistor 6.

2 to 4 are a cross-sectional view, a top view, and a sectional view taken along the line ff-ff in FIG. 2, showing the tool post 5. That is, the tool holder g4 is held with respect to the tool rest 5 via a hydrostatic bearing so that it can move forward and backward in the Y@ direction in the figure. A cutting tool J41 is attached to the front end of this tool holding part 4, and a minute f-position element 6 is interposed between the rear end and the end wall 5A protruding from the end of the tool rest 5, and both ends thereof are It is a solid layer.

FIG. 5 is a battle face diagram showing an example of the butterfly micro-displacement element 6, in which, for example, three piezoelectric elements 6It are arranged in a layered manner with electrodes 62, 63, 64° 65, such as silver foil, interposed between both ends and 1. 41! ! A connecting member 67 is provided via # bodies 66 and 66.

Then, the voltage *es*tt4 is grounded, and a voltage of several hundred volts is applied between this ground level and the voltage 62.65 to cause the piezoelectric element 61 to expand and contract in the stacking direction.

FIG. 6 is a diagram showing an example of the relationship between the voltage applied to such a minute f-level element 6 and the amount of extension Δl. For example, when the thickness lxl
Suppose that it is possible to apply a voltage of =500v to a pressure 11E element of m and give an elongation of 0.25μ. Here, the applied voltage is controlled within the range of 500±300v to drive the piezoelectric element 111I! If a displacement of ±0.15μ is to be produced, by stacking three piezoelectric elements, the entire displacement will be 0.15μ.
．． The thickness can be controlled within the range of 3μ to 1.2μ. On the other hand, the change in thickness of such a minute displacement element with respect to the applied voltage becomes approximately linear when the voltage is controlled within an appropriate range, and the response is also extremely good. Therefore, by controlling the voltage applied to the minute f-position resistor 6, the tool holder 4 can be driven in the Y-axis direction relative to the tool rest 5, and the position of the cutting tool 1 can be controlled. .

In FIG. 1, reference numeral 7 denotes an X-axis drive mechanism for driving the tool rest 5 in the X-axis direction, and includes, for example, a drive motor and a shaft that is rotationally driven by this motor. The X@ drive handling mechanism 1 drives the tool post 5 at a constant speed in the X-axis direction by the X-axis servo amplifier 9 in accordance with the setting value of the X-axis movement speed setter 8. In addition, 10 is a Y that drives the tool rest 5 in the Y@length direction.
s drive@Shiru, for example with a drive motor.

A feed screw is provided which is rotationally driven by this motor and which is screwed into the tool rest 5.

The drive motor is controlled by the Y-axis servo amplifier II to drive the tool post 5 in the Y-axis direction.

Reference numeral 12.13 denotes an X-axis sub-length measuring device and a Y-axis sub-length measuring device for detecting the position fil of the tool holding portion 4 in a non-contact manner, such as a laser length measuring device that utilizes interference from a laser source. In addition,
Since the cutting tool 1 is attached to the tool holder 4, the position of the cutting edge at the tip of the tool 1 to be cut can be determined from the position of the tool holder 4. and then move the tool holder 4 in the X-axis direction every fixed distance from the X-axis sub-length tool 12.
For example, a pulse is output every 0.01μ. Also Y4
1] A pulse is similarly output from the ya length measurement 91B in response to movement in the direction. Then, the output pulse of the XS length measuring device 12 that detects the position in the X-axis direction is sent to the X-axis position counter 14.
The position of the tip of the cutting tool l in the X-axis direction is detected by counting. The count of this X-axis counter 14 is 1 [x
fcx) to the Hiroma circuit 15. This f(ri calculation circuit 15 calculates the theoretical position f (X,) on the Y axis corresponding to the position X on the X axis of the cutting J411 according to the desired cutting direction. f (rJ'&
g and one input of the addition register 19. On the other hand, the output pulse of y@length measurement@IB is the Y-axis position counter 2.
The count value corresponding to the position of the cutting edge on the cutting surface 141, ie, the Y-axis actual measurement value yk, is supplied to the second comparator 18 via the first comparator 17 and the hold circuit 21. Then, the output of the first comparison 527 is converted into a voltage at a predetermined ratio by the minute displacement element drive circuit 22, and the output is converted into a voltage at a predetermined ratio to
Apply to.

The second comparator 18 also has a count value of the Y@position counter 20 held in the hold circuit 21, that is, an actual measurement value y.
and the logical value Y of the data register 16 are given, their contents are compared, and each time the difference exceeds a predetermined value Δγ, a certain distance ll is added to the other input of the addition register 19.
Apply Y to the drive signal to drive l. And the Y-axis servo amplifier 11 is given the addition output of the addition register 19.
In response to this drive signal, the tool rest 5 is driven stepwise by a predetermined distance ΔY. By setting the predetermined value Δy to an appropriate value, the control voltage for the minute displacement element 6 is maintained within an appropriate range, and the straightness is not affected or an excessive voltage is not applied.

With such a configuration, prior to the start of cutting, the "cutting tool 1" is connected to the workpiece S by the IIIJ# thread (not shown).
The machining origin is driven to X0eY (1, and all counters and registers are reset. Then, when cutting starts, the X-axis servo amplifier 9 is valved according to the setting value of the X @ movement speed setting device 8, and the Xa drive mechanism 1, a cutting tool 1 is driven at a constant speed from the outer periphery of the workpiece S toward the center.

Then, depending on the position of the tool rest 4 that holds the cutting tool 1 in the X-axis direction, the
A pulse is output every time. And this pulse is x@ca
The counter 14 counts to obtain the actual measurement value X of the cutting tool 1 with respect to the machining origin XoK. This measured value X is given to the f(g) arithmetic circuit 16 for calculation, and a logical value Y in the Y-axis direction corresponding to the value is given to the addition register 19 via the data register 16. In this case, since the actual measurement value I is given as a digital value from the K is set so that the value of the actual measurement value X is updated and the calculation is performed.

On the other hand, depending on the position of the cutting tool 1 in the Y-axis direction, Y-axis - Jfk
Pulses output from the Y-axis position counter 20 are counted by the Y-axis position counter 20, and this actual value y is held in synchronization with the update of the output data of the first comparator 17 and the upper HeX@Iffli1 counter 14. The signal is applied to the hold circuit 21.

Then, the actual measured value y outputted from the hold circuit 21 and the theoretical value Y given from the data register 16 are given to the second comparator 18 for comparison, and each time the difference exceeds a predetermined value Δyk, the other of the addition registers I9 This output drives the Y41] driving mechanism 10 via the Y-axis servo amplifier 11, and moves the position of the cutting tool 1 in the Y-axis direction by ΔY in steps. At the same time, the first comparator 17 divides the measured value y from the theoretical side Y, converts it into a voltage via the minute displacement element drive circuit 21 according to this value, and controls the voltage applied to the minute displacement element 6. to control the position of the J4 deep holding part 4.

Here, in FIG. 1, the second comparator 18, addition register 192, and hold circuit 21 are not provided, and the data register 1
6 output to the first comparator 17 and Y-axis servo amplifier 1
Think about what you give to 1. In this case, for example, as shown in Figure @7, the cutting tool l is moved to the machining origin (X・, Yo
) in the X-axis direction, the theoretical value f (X6) * f (11)
ef(it)... is given. Note that this theoretical value f((transformation) is the ideal curve 4 [1
1FCX:. Then, the Y-axis section #isostructure 10 is driven via the Y-axis servo amplifier 11 according to the above-mentioned theoretical value f(to), and the actual measured value y gradually changes to the theoretical value f(
approach). Then, during this period of time, the difference between the measured value y and the theoretical value f(2) is obtained by the first comparator 17, and this value Yl is applied to the minute displacement element 6 via the minute displacement element drive circuit 22t to drive it. That's what I do. However, in such a case, the actual measured value y, such as the position xs on the X axis shown in the diagram
The theory (if(d) and when the difference becomes large enough, the signal Yσ that controls the minute displacement element 6 also becomes large,
If the linearity is exceeded by deviating from the proper control range, the motor may become uncontrollable.

On the other hand, in the actual WAfPIl, as shown in FIG. 8, when the second comparator 18 detects that the difference between the actual value y and the theoretical value f (X) exceeds the predetermined value Δy, the drive is driven a predetermined distance. The drive signal ΔY to be added is supplied to the adder circuit 19. Therefore, the Y-axis servo amplifier 11 is given a signal that is the sum of the theoretical value f(ri) and the drive signal ΔY, and the difference between the apparent theoretical value f((revolution) and the actual value y becomes large). As a result, the Y-axis servo amplifier 11 drives the Y-axis drive mechanism IO with this apparent difference as a target, so the actual measured value y rapidly approaches the theoretical value f (d. Therefore, the drive signal for the minute displacement element 6 Yσ can be controlled within a predetermined appropriate range ±Cmaw, and good linearity and accurate control can be achieved.

Therefore, the error caused by the mechanical drive mechanism regarding the position of the cutting tool in the direction of cut is corrected by a minute f-position element that utilizes the magnetic pressure solder effect, and if the voltage applied to this minute displacement element exceeds the appropriate range. Since the cutting tool is driven by the drive mechanism to reduce the amount of correction, the minute displacement element always operates within an appropriate range.

Note that the present invention is not limited to the above-mentioned implementation sequence; for example, the actual measurement value X returned from the output pulse of the Alternatively, f(→The calculation circuit may be one that quickly calculates the theoretical value Y in the Y-axis direction of the desired cutting surface S from the given actual measurement value X. The present invention is not limited to this, and for example, a memory may be provided in which a logical value Y calculated in advance is stored, and the stored contents may be sequentially read out by VC.

Furthermore, since the minute f-position element has a very good response to the drive signal, if it is sensitive, the output of the tenth ratio e unit 17 and the minute displacement element drive circuit 23 are connected to each other as shown by the broken line in FIG.
An integrating circuit 22 may be inserted between the two. FIG. 9 is a diagram showing one line of such an integrating circuit 23. For example, a multi-bit digital signal given from the first comparator 17 is converted into an analog signal by a digital-to-analog converter DA, and then connected to a resistor R, and the first switch SW, decrement via: @device op.

Enter. This operational term I6op is an integral capacitor C, a discharge resistor R1, and a second switch SW between input and output.
, are connected in parallel. And the first switch SW! selects the resistor R1, and the second switch 8W
! is opened to integrate the above analog signal, and after the integration is completed, select the first switch sw, #'i ground potential side, and close the second switch sw, to discharge the photoelectric charge of the integrating capacitor C. .

FIG. 10 is a circuit diagram showing the minute displacement element drive circuit 22, in which a transistor Tr 31 (b) is used to control the applied voltage of several hundred volts to the minute displacement element 6.
The collectors and emitters of l, Try, and Try are connected in cascade. That is, the signal Yσ applied to the input terminal TK is applied to the base of the transistor Trl via the buffer amplifier OPl. On the other hand, transistor Trl
The construction of *Tr2 *Try connects the ivy and collector in cascade, and connects the collector and base of transistor Tr3, transistors Try, Tr! Resistors R, , R, , R are inserted between the bases of the transistor Try and the emitter of the base transistor Tr1 of the transistor Try. A power supply P of several hundred volts and a minute displacement element 6 are connected between the emitter of the transistor Tr1 and the collector of the transistor Try.
A series circuit is connected. In this way, each transistor T r 1 1 T r ! The voltage applied between the emitter of lTrH and the transistor Trl is approximately 1/3 of the wake-up pressure of #L, and the voltage applied between the emitter of transistor Trl and the transistor Trl,
Tr! The requirement for the collector breakdown voltage of eTrl can be relaxed.

Furthermore, in the above actual IM example, f(phantom calculation circuit 15 is configured to output the theoretical value Y for the machining origin Y0, but the previous position in the X-axis direction
The difference YH-Yn-1 between the logical value yn-t corresponding to 5 and the logical value Yn corresponding to the current position Xn in the X-axis direction may be output.

As described in detail above, according to the present invention, the positional difference in the cutting direction of the cutting tool caused by the mechanical drive mechanism can be corrected by a micro-displacement element whose displacement is electrically controlled, and the micro-displacement element When the voltage applied to the cutting tool exceeds an appropriate range, the cutting tool is driven by the drive mechanism to reduce the amount of correction.

Therefore, it is possible to provide a mechanical cutting system that is capable of cutting quadratic curved surfaces with extremely high precision and that allows the minute displacement element to always operate within an appropriate range.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG.
3 and 4 are a plan view showing the above-mentioned actual AI turret, a J11 side view, a view taken along the line IY-mV in FIG.
The figure is a four-sided view showing an example of the minute displacement element of the above-mentioned example, Figure 6 is a diagram showing the relationship between the applied voltage and the amount of extension of the minute displacement element, and Figure vfJ7 explains the operation of the conventional device. Fig. 8 is a diagram explaining the operation of the device of the present invention, Fig. 9 t
Another fruit of this invention! The 10th is a diagram showing an integration circuit of M columns, and the 10th diagram is a diagram showing one part of the micro-displacement element drive circuit of the present invention. l... Cutting tool, 2... Rotating shaft, 3... Loe object, 4... Tool holding part, 5... Tool rest, 6... Micro displacement element, 7... X @ drive mechanism, 10...ys drive mechanism, 12...X-axis length measuring device, 13...Y@sub length device,
15...f (phantom circuit, 17... first comparator,
18...Second Ratio II! ! 2 vessels. Figure 1 Figure 2? f! 3! '1 9th vA 10th Ward・

Claims (1)

[Scope of Claims] A workpiece that is held and rotationally driven by a rotating shaft, a tool holder that holds a cutting tool for cutting this workpiece, a tool rest that holds this tool holder, and a tool rest that holds this tool holder. an X-axis drive mechanism that drives the tool rest in a direction perpendicular to the cutting direction of the cutting tool; and the tool holder and the tool rest. an X-axis and a micro-displacement element that is interposed between the tool rest and drives the tool rest in the cutting direction with respect to the tool holder, and an X-axis and a An f (g) arithmetic circuit that outputs a logical value in the Y-axis direction of a desired cutting surface according to the actual measured value given from the Y@ side lengthening device and the X-axis lengthening device; a micro-displacement element driving circuit that displaces the micro-displacement element in the cutting direction according to the difference between the theoretical value given by the Y@side length machine and the actual value given from the Y@side length machine; and a second comparator that drives a Y-axis drive mechanism to maintain the f position in the micro-displacement confectionery within a predetermined range.