JPS61132816A - Numerical control device - Google Patents

Abstract

PURPOSE:To raise the accuracy and the reliability by extracting selectively a side quantity from an inclination of a free curved surface in a measuring point and a contact pressure of a displacement gauge, and correcting a read value by a red error calculated from its slide quantity. CONSTITUTION:When measuring a shape of an object to be worked 3 which has been worked by a tool 6, a contact pressure of a micro-displacement gauge 11, a correlative data of a component force and a slide quantity in the X axis direction of the contact pressure of its displacement gauge 11, and a free curved surface constant are inputted in advance to an external storage device 14 from a keyboard 16. In this state, the micro-displacement gauge 11 is positioned at an optional measuring point, and thereafter, a displacement quantity is inputted, and also a process for correcting the input value by a quantity corresponding to the slide quantity is repeated in an optional deciding range.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a numerical control device having a function of measuring the shape of a workpiece having a free-form surface using a contact type displacement type.
More specifically, the present invention relates to a numerical control device that measures the shape accuracy of a workpiece (object to be measured) having a free-form surface shape in equipment such as a lathe, a machining center, and a three-dimensional measuring device.

[Background of the invention]

As a lathe device using numerical control of this type, one having a configuration as shown in FIG.
Publication No. 45). This configuration was developed by the applicant.

In the numerically controlled lathe shown in Fig. 4, 1 is the processing machine main body, 2 is a chuck that grips the workpiece 3, 4 is an XZ table, and 5 is a
6 is a tool stand, 6 is a cutting tool, 7a and 7b are motors for moving the XZ child table, and 7c is a motor for driving the chuck 2 in the direction indicated by the arrow. Also, 11 is a tool stand 5
12 is an amplifier circuit for amplifying the detection output signal from the detector 11, and 13 is an A/D converter for converting an analog signal into a digital signal.

Further, 8 indicates an NC control device, which includes a tape reading section 81 that reads data from the NC tape 9, an arithmetic processing device 82, a control section 83, amplifiers 84a, 84b, 84c, and detecting data from the detector 11. It consists of a data input section 85 for inputting data to the arithmetic processing device 82 and an external display control section 87 for controlling the display of output data from the arithmetic processing device 82 on an external display (CRT) 15 .

This configuration is for measuring the workpiece 3 by simultaneously controlling the contact type detector 11 in two axes in the x and Z directions. That is, in order to measure the free-form surface shape of the workpiece 3 machined with the tool 6, the measurement control command information is stored in the N
Each drive motor 7a, 7 is activated by a command from the C tape 9.
By driving b, the xZ child table is arbitrarily driven, and the arithmetic processing unit 82 reads the amount of displacement of the minute displacement meter 11 at each measurement point, and calculates the shape error.

FIG. 2 is a diagram illustrating the slipping situation in the minute displacement meter 11 of FIG. 4, and the case where the shape at an arbitrary measurement point Pi is measured by the minute displacement meter 11 will be described as follows.

That is, the tactile pressure of the minute displacement meter 11 causes the displacement meter body or the mechanism supporting the displacement meter to slip in the direction of point P'i. Therefore, the arithmetic processing device 8 shown in FIG.
2 is judged as measurement information at point Pi, so there is a problem that the displacement amount read by the central processing unit 82 includes an error ΔZi due to slippage of the displacement meter. The error AZi due to this slippage increases in proportion to the magnitude of the contact pressure of the minute displacement meter 11 and the inclination of the free-form surface at the measurement point.

In addition, FIG. 3 is a graph in which the amount of slip ΔXi in the apparatus shown in FIG. 4 is plotted for each magnitude of the X-axis direction component force Fx of the displacement meter tactile pressure. As is clear from Fig. 3, in order to eliminate the above-mentioned problem, it is necessary to reduce the contact pressure of the minute displacement meter 11 to less than Igf, but such a displacement meter is extremely expensive and is not a good idea. do not have.

[Purpose of the invention]

The present invention has been made in view of the problems in the prior art described above, and it is an object of the present invention to provide a numerical control device that improves measurement accuracy, can be configured with an inexpensive displacement meter, and is compatible with automation.

[Summary of the invention]

In order to achieve the above object, the present invention measures in advance the X-axis direction component of the displacement meter contact pressure and the slip amount in a numerical control device, and stores the measured values.

From the inclination of the free-form surface of the workpiece at any measurement point and the tactile pressure of the minute displacement meter used, the X-axis component force of the tactile pressure of the displacement meter (
Fx), the calculated result is compared with the stored result, the amount of slip is determined from the comparison result, and the measured value is corrected based on the amount of slip.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIG.

(Embodiment 1) In FIG. 1, the same reference numerals as in FIG. 4 have the same functions. In FIG. 1, there is an external storage device 14 that stores correlation data between the aspherical constant of the cross section of the workpiece, the contact pressure of the minute displacement meter, the X-axis component force of the minute displacement meter, and the slip amount, etc. A keyboard 16 for inputting and instructing correlation data, etc., an external storage device control section 86, and a keyboard information input circuit 88 are additionally installed.

That is, in FIG. 1, the tool 6 and the contact-type minute displacement meter 11 are fixed to the tool stand 5. As shown in FIG.

Further, the tool stand 5 has a table drive motor 7a.

7b is fixed to the upper surface of the xZ child table which can be moved in the Z and X axis directions, respectively.

The xZ child table is installed in the processing machine main body 1.

Further, a workpiece 3 is attached to a chuck 2 in the processing machine main body 1 so that its axis is parallel to two axes.

Note that the output signal from the minute displacement meter 11 in this example is amplified by an amplifier circuit 12 and further converted into a digital signal by an A/D conversion circuit 13.

On the other hand, the trajectory command of the minute displacement meter 11 for performing on-machine measurement is programmed in advance on the control command tape 9, and the information from this control command tape 9 is read and the table drive motors 7a, 7b and spindle drive motor 7 are
A numerical control device 8 is installed to control c.

This numerical control device 8 is connected to an external storage device (FD
)14 external storage device control unit 86 for reading the information of 14
, an external display controller 87 that outputs information to the printer or CRT external display 15 that outputs shape error analysis processing results, etc., and the control command tape 9.

A tape reading section 81 for reading information, and outputting a command for moving the xz child table based on the information read by the tape reading section 81, as well as basic information for measurement value correction processing and the correction processing, which will be described later. An arithmetic processing unit 82 performs arithmetic processing such as creating a slip correction map, and an xZ child table and a spindle (not shown) equipped with a workpiece 3 at the tip are driven based on output commands from the arithmetic processing unit 82. Respective drive motors 7a, 7b, 7
a control section 83 for controlling the drive of the drive motors 7a to 7C; a data input section 85 for inputting the data information output from the arithmetic processing section 13 and outputting the results from the arithmetic processing section 828; It consists of a keyboard information input circuit 88 that reads key-in information from the keyboard 16 indicating correlation data between the component force in the X-axis direction and the amount of slip.

Now, in order to measure the shape of the workpiece 3 after machining with the tool 6, the contact pressure of the minute displacement meter 11, the correlation data between the component force in the X-axis direction of the contact pressure of the displacement meter 11 and the slip amount, and Free-form surface constants are input in advance into the external storage device 14 from the keyboard 16. x due to measurement control command from NC tape 9
The Z table is driven to position the minute displacement meter 11 at the point Pi in FIG. 2, and the displacement Ω'i is input. Here, since the input displacement amount a' is a value measured at the point P'i where the slippage occurred, the following correction is performed.

In other words, the slope at point Pi (Xi, Zi) of a free-form surface generally expressed as F (X) is expressed by the first-order differential equation F'
Arctangent of (Xi) (θi = tan""(F'
(Xi) )), the X-axis direction component force FXi of the minute displacement meter contact pressure at point Pi is F Xi = tanθiF = tan(tan-'(
F'(Xi))・F=F'(Xi)・F
......(1). Here, F: tactile pressure of the minute displacement meter (gf) From the correlation data between the force in the X-axis direction of the tactile pressure of the minute displacement meter and the amount of slip, which was input in advance.

The slip amount ΔXi at the time of the component force FXi is extracted, and the measured value is corrected as follows.

In other words, the true measured value Qi is Ωi=Q'i+Δ2 (2
) where ΔZi=tan θ・AXi=F' (Xi)
・AXi ... Since it can be approximated by (3), (Equation 2
) (Formula 3), Mi=Q'i'+F'(Xi) ・
AXi --(4).

In this way, after positioning the minute displacement meter at an arbitrary measurement point, the process of inputting the amount of displacement and correcting the input value by an amount corresponding to the amount of slip is repeated in an arbitrary determination range.

According to this embodiment, since the reading error caused by the displacement meter slipping is corrected from the position of the minute displacement meter immediately after the first positioning, highly accurate measurement can be achieved.

(Example 2) In Example 1, a case was described in which the reading error was calculated from the amount of slippage that occurred and was corrected from the actual reading value. X of
Find the axial component force FXi, and extract the slip amount ΔXi when the component force FXi is the same from the correlation data between the X-axis component of the small displacement meter tactile pressure and the slip amount, which was input in advance. Correct the measurement point coordinates as follows. That is, X1=Xi-AXi Zi=F(X'i)+1'1=F(Xi-AXi)-1
11'i = 45) Therefore, the shape error can be determined by comparing the ideal free-form surface shape at t'i with the measurement point coordinates determined by equation (5).

According to this embodiment, since the points at which slipping occurs are compared with the ideal free-form surface shape, the effect of highly accurate shape measurement can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, when measuring a workpiece (or object to be measured) having a free-form surface shape with a numerical control device using a contact-type micro-displacement meter, measurement is performed in advance and stored. Based on the correlation data between the minute displacement meter and the amount of slip,
The amount of slip is selectively extracted from the inclination of the free-form surface at the measurement point and the contact pressure of the displacement meter, the reading error is calculated from the amount of slip, and that error is eliminated from the reading value, resulting in extremely high accuracy and reliability. This has the effect of allowing highly accurate shape measurement. Moreover, since there is no need to use a particularly high-precision displacement meter, an inexpensive measurement system can be constructed.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of a numerical control device showing an embodiment of the present invention, Fig. 2 is a diagram illustrating the slipping situation of a minute displacement meter,
FIG. 3 is a characteristic diagram for explaining the X-axis component force of the displacement meter contact pressure, and FIG. 4 is a schematic configuration diagram of a numerical control device previously developed by the applicant. 1... Processing machine main body, 2... Chuck, 3... Workpiece. 4...xZ child table 5...tool stand, 6...tool, 7a-7c...table drive motor, 8...numerical control device, 9...NG tape, 11...micro Displacement meter, 12... Amplification circuit, 13... AD conversion circuit, 1
4... External storage device, 15... External display, 16.
...Keyboard, 81...Tape reading unit, 82...
Arithmetic processing unit, 83...control unit, 84a-84c...
- Amplifier section, 85... Data input section, 86... External storage device control section, 87... External display control section, 88.
・・Keyboard information input circuit・ Agent Masaaki Akimoto, Patent Attorney Figure 1 Figure 2 Zi Z Figure 3 Figure 4

Claims (1)

[Claims] In the numerical control device that measures the shape accuracy of a free-form surface of the workpiece on a table movable in at least two axes using a minute displacement meter that detects the displacement of the workpiece (or the object to be measured), input means for instructing and inputting information such as the tactile pressure of the minute displacement meter, the correlation data between the component force in the X-axis direction of the tactile pressure of the displacement meter and the slip amount, and the free-form surface constant; an external storage means whose reading is controlled by the input means; a control means which controls the positioning of at least one of a workpiece forming a free-form surface shape or the minute displacement meter; It is equipped with a shape detection means capable of measuring a cross-sectional shape, and an arithmetic processing means for eliminating detection errors from the data obtained from the detection means, and the control means is configured to detect a measurement point at an arbitrary measurement point on the workpiece. determining the amount of slippage of the minute displacement meter when positioning the minute displacement meter, calculating a detection error corresponding to the amount of slippage, and eliminating the detection error from the data obtained from the detection means. A numerical control device that measures the shape accuracy of the workpiece.