TWI460567B - Method for error compensating and method for measuring workpiece using the same - Google Patents

Description

Error correction method and workpiece measurement method using the error correction method

The invention relates to an error correction method and a workpiece measurement method using the error correction method, in particular to an error correction method and a workpiece measurement method using software processing.

In the field of ultra-precision measurement, methods for improving measurement accuracy generally start with hardware design, such as contact measurement devices with high measurement accuracy. In order to ensure the measurement accuracy, high-precision precision parts such as high-precision guide rails, probes and interferometers are usually used in contact measuring devices. In addition, in order to obtain accurate measurement results, the mechanical transmission and assembly accuracy of the measuring device are also highly demanded, which further increases the manufacturing cost of the measuring device. Therefore, the overall price of the existing ultra-precision measuring devices is generally very high, which limits the wide application of ultra-precision measuring devices.

In view of the above situation, it is necessary to provide an error correction method which can reduce the cost of the measuring device and can ensure the measurement accuracy, and a workpiece measuring method using the error correction method.

An error correction method includes the following steps: providing a measuring device, the measuring device comprising two probes and a guide rail; measuring and correcting the true straightness error of the guide rail, and performing true straightness error on the guide rail During the measurement process, a standard ball and a standard plane are provided, so that the standard ball and the standard plane are respectively located on two sides of the measuring device, and one of the probes is in contact with the surface of the standard ball to measure the standard ball, and another test is performed. The head is in contact with the standard plane to measure the standard plane. The measurement of the standard sphere and the standard plane and the installation tilt error of the standard plane are used to obtain the true straightness error of the guide rail; fitting the installation tilt angle of the probe; The shape error of the probe; and the system error correction file is generated.

A workpiece measuring method includes the following steps: providing a measuring device comprising two measuring heads and a guide rail; measuring and correcting the true straightness error of the guide rail, and providing a standard in the process of measuring the true straightness error of the guide rail The ball and the standard plane are such that the standard ball and the standard plane are respectively located on two sides of the measuring device, one of the probes is in contact with the surface of the standard ball to measure the standard ball, and the other probe is in contact with the standard plane to the standard The plane is measured, and the true straightness error of the guide rail is obtained by measuring the standard sphere and the standard plane and the installation tilt error of the standard plane; fitting the tilt angle of the probe; calculating the shape error of the probe; generating system Error correction file; providing a workpiece having a curved surface or a curved line; measuring the curved surface or curve of the workpiece by using a measuring device; The true straightness error of the guide rail is measured and corrected; the tilt angle error of the probe is corrected; the shape error of the probe is corrected; and the system generates measurement error.

In the above error correction method and the workpiece measurement method using the error correction method, high measurement accuracy can be obtained by correcting the error of the measurement device due to various factors. Since the effect of various errors on the measurement accuracy is reduced by the method of software correction, the accuracy requirements for manufacturing, assembly, and transmission of the measuring device using the error correction method can be appropriately reduced to reduce the number of precision parts used at higher prices. Thereby, the manufacturing cost of the measuring device is greatly reduced.

100‧‧‧Error correction method

20‧‧‧Measurement device

21‧‧‧ probe

23‧‧‧ rails

40‧‧‧Standard ball

50‧‧‧ standard plane

200‧‧‧Workpiece measurement method

60‧‧‧Workpiece

1 is a flow chart of an error correction method according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of measuring a standard sphere in the error correction method shown in FIG. 1. FIG.

3 is a flow chart of a workpiece measuring method according to an embodiment of the present invention.

Fig. 4 is a schematic view showing the measurement of the workpiece in the workpiece measuring method shown in Fig. 3.

The error correction method provided by the present invention and the workpiece measurement method using the error correction method will be further described in detail below with reference to the accompanying drawings and embodiments.

Referring to FIG. 1 and FIG. 2, the error correction method 100 provided by the present invention includes the following steps: S102, providing a measuring device 20, which is a contact measuring device, including a measuring head 21 and a guide rail 23, in the measuring device 20 The number of the probes 21 is two; S104, the true straightness error e ₁ of the guide rail 23 is measured and corrected; the true straightness error e _{1 of the} guide rail 23 can be measured and corrected by the following method. First, a standard ball 40 and a standard plane 50 are provided such that the standard ball 40 and the standard plane 50 are respectively located on two sides of the measuring device 20. Next, one of the probes 21 of the measuring device 20 is brought into contact with the surface of the standard ball 40 to measure the standard ball 40. Another probe 21 is in contact with the standard plane 50 to measure the standard plane 50.

Then, a probe 21 scans the surface of the standard ball 40 to obtain a series of scan data (Xn, dz1 _n ) of the standard sphere 40 (n = 1, 2, 3, ...). The other probe 21 measures the standard plane 50, and the offset data (Xn, dz2 _n ) of the guide rail 23 (n = 1, 2, 3, ...) can be acquired.

A straight line fit is performed based on the offset data (Xn, dz2 _n ) to obtain a fitted value k and an additional value b.

The standard plane 50 is stored in the tilt error. Assuming that the tilt angle of the standard plane 50 is θ, the tilt angle can be obtained according to the following formula: k=tan θ (1)

The true straightness error e1 of the guide rail 23 is: e1=dz2 _n -(k*Xn+b) (2)

After the correction of the true straightness error e1 of the guide rail 23, the correction value L1 is: L1=dz1 _n +e1 (3)

S106, fitting the mounting tilt angle α of the probe 21; the tangent angle of the contact point between the probe 21 and the standard ball 40 is β, and since it is stored at the installation tilt angle α, it is assumed that the true straightness error e _{1 of the} guide rail 23 is corrected. The measured value is L ₂ , then: L ₂ = L ₁ *(cos(α)+sin(α)*tan(β)) (4)

Assuming that the probe 21 does not have a theoretical value L' when the tilt angle α is installed, the mounting tilt angle α of the probe can be fitted by a nonlinear least squares method.

S108, calculating the shape error e ₂ of the probe 21; obtaining the true straightness error e ₁ of the guide rail 23 and the mounting tilt angle α of the probe 21 by the foregoing steps, according to the following formula: e ₂ =L ₁ -L' ( 5)

The shape error e _{2 of the} probe can be obtained.

S110, generating a system error correction file.

According to the obtained shape error e ₂ , it is associated with the tangent angle β of each contact point of the probe 21 and the standard ball 40, and a systematic error correction file can be generated.

Referring to FIG. 1 , FIG. 3 and FIG. 4 simultaneously, the workpiece measuring method 200 provided by the present invention includes the following steps:

S202, generating system error correction data by using the error correction method 100;

S204, providing a workpiece 60 having a curved surface or a curved line;

S206, using the measuring device 20 or a curved surface of the workpiece is measured; hypothesis of the workpiece is A, the measurement is not performed when the correction value A _1.

S208, measuring and correcting the true straightness error e of the guide rail 23; Since the true straightness error e of the guide rail 23 may vary at each measurement, the true straightness error e of the guide rail 23 can be measured and corrected in the same manner as in the step S104.

S210, the installation tilt angle α error of the probe 21 is corrected; because the installation tilt angle α of the probe 21 is a fixed value, after the true straightness error e of the guide rail is measured in step S208, the computer can measure the probe 21 The installation tilt angle α error is automatically corrected.

S212, the shape error e ₂ of the probe 21 is corrected; since the shape error e _{2 of the} probe 21 is also a fixed value, the computer can automatically correct it.

S214, the system generates a measurement error Err.

By the foregoing steps, the measured value A ₂ after correction of various errors can be calculated: A ₂ = (A ₁ + e) * (cos (α) + sin (α) * tan (β)) - e ₂ (6)

Therefore, the measurement error Err is obtained: Err=A ₂ -A=(A ₁ +e)*(cos(α)+sin(α)*tan(β))-e ₂ -A (7)

In the embodiment of the present invention, the software correction method for establishing a mathematical model in the computer is used to correct various errors in the measurement, thereby obtaining higher measurement accuracy and reducing the manufacturing, installation and transmission of the measuring device 20. The accuracy is required, so the cost is reduced.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and cannot be limited thereto. The scope of the patent application for this case. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

Claims (8)

An error correction method includes the following steps: providing a measuring device, the measuring device comprising two probes and a guide rail; measuring and correcting the true straightness error of the guide rail, and measuring the true straightness error of the guide rail a standard ball and a standard plane, the standard ball and the standard plane are respectively located on two sides of the measuring device, one of the probes is in contact with the surface of the standard ball to measure the standard ball, and the other probe is in contact with the standard plane The standard plane is measured, and the true straightness error of the guide rail is obtained by measuring the standard sphere and the standard plane and the installation tilt error of the standard plane; fitting the installation tilt angle of the probe; calculating the shape error of the probe; And generate system error correction files. For example, in the error correction method described in claim 1, wherein one of the two side heads scans the surface of the standard ball during the measurement of the true straightness error of the guide rail, and obtains a series of scanning of the standard ball. Data, another probe on the two side heads measures the standard plane, can collect the offset data of the guide rail, and perform straight line fitting according to the offset data to obtain the fitted value and the added value, and the fitting value is equal to the inclination of the standard plane. The tangent of the angle, based on the offset data, the fitted value, and the added value, the correction value after the correction of the true straightness error of the guide rail is obtained. The error correction method described in claim 2, wherein the installation tilt angle of the probe is fitted by a least squares method. The error correction method according to claim 1, wherein the measuring device is a contact measuring device. A method of measuring a workpiece, comprising the following steps: Providing a measuring device comprising two probes and a guide rail; measuring and correcting the true straightness error of the guide rail, and providing a standard ball and a standard plane during the measurement of the true straightness error of the guide rail, so that the standard ball is provided And the standard planes are respectively located on both sides of the measuring device, one of the probes is in contact with the surface of the standard ball to measure the standard ball, and the other probe is in contact with the standard plane to measure the standard plane, by using the standard ball And the standard plane measurement and the standard plane installation tilt error, the true straightness error of the guide rail is obtained; the installation tilt angle of the probe is fitted; the shape error of the probe is calculated; the system error correction file is generated; and a workpiece is provided. The workpiece has a curved surface or a curved line; the surface or curve of the workpiece is measured by a measuring device; the true straightness error of the guide rail is measured and corrected; the tilt angle error of the mounting head is corrected; and the shape error of the measuring head is corrected; And the system generates measurement errors. The workpiece measuring method according to claim 5, wherein in the step of measuring and correcting the true straightness error of the guide rail, one of the two side heads scans the surface of the standard ball to obtain a series of standard balls. Scanning data, the other side of the two heads measure the standard plane, the offset data of the guide rail can be collected, and the straight line fitting is performed according to the offset data to obtain the fitted value and the added value, and the fitting value is equal to the standard plane. The tangent of the tilt angle is based on the offset data, the fitted value, and the added value to obtain a correction value after the true straightness error of the guide rail is corrected. The workpiece measuring method according to claim 6, wherein the mounting tilt angle of the probe is fitted by a least squares method. The workpiece measuring method according to claim 5, wherein the measuring device is a contact type measuring method Measuring device.