JPS61131854A - Measuring apparatus for workpiece machined by lathe - Google Patents

Abstract

PURPOSE:To efficiently carry out a measurement of machining with pinpoint accuracy by providing a measuring apparatus for a workpiece machined by a lathe with means for correcting a setup error of a workpiece, an accuracy error of a machine, and an error due to thermal deformation when a machining and a measurement are carried out by a large lathe using the indication of a present position. CONSTITUTION:A measuring apparatus for a workpiece machined by a lathe is provided with a laser length measuring machine 11 for an X axis of a machine, a laser length measuring machine 9 for a Z axis, a laser length measuring machine 8 for straightness, and a laser length measuring machine 10 for tilt. Further, the measuring apparatus automatically corrects data measured by laser at all times using an interface 14 for correction, an air sensor 15, and an object temperature sensor 16-A, 16-B to keep various dimensions measured by laser unchanged for minimizing effects on a measuring accuracy due to thermal deformation of a workpiece 4. The measuring apparatus is also provided with a microcomputer 17 for storing data from an interface 13 for the length measuring machines and for performing arithmetic operations on the data, a present position indicating unit 19 for indicating the result of the arithmetic operation, and a touch sensor 12 taking the place of a cutting tool tip for accurately measuring the axial diameter and length of the workpiece.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a lathe workpiece measuring device, and particularly to a device for measuring workpieces on a lathe, which corrects setup errors and machine precision errors of loaded workpieces on a large lathe.
The present invention relates to a lathe workpiece measuring device suitable for making it possible to measure the true dimensions of a workpiece. .

[Background of the invention]

Traditionally, the finishing accuracy measurement of workpieces on large machine tools is
There are cases in which direct measurement is performed using a micrometer or bow gauge, and cases in which the current position is displayed using a dedicated high-resolution scale attached to each axis of the machine, and measurements are made using this as a reference. In the former case, you will need to prepare a large micrometer or bow gauge each time.

It requires a lot of time, effort and measurement know-how. On the other hand, in the latter case, since it can be measured by the movement of the mechanical feed axis, it has the advantage that it is simple and can be measured in a short time. Table 1 is an example of literature on measurement using the conventional current position display function.

Table 1 However, the larger the machine tool, the more likely it is to be affected by setup errors or machine precision of the workpiece, and the current position display and
The error between the actual size and the actual size increases, and for parts that require high precision, a large micrometer or bow gauge must be used.

Hereinafter, problems in using the current position display function in conventional large machine tools, particularly large lathes, will be explained.

(1) First, there is the influence of setup errors of the workpiece.

FIG. 9 is an explanatory diagram showing the setup error of a workpiece in a large lathe, and shows the relationship between the machine body and the workpiece. 1 is a spindle head stock, 2 is a spindle face plate, 3 is a workpiece head, 4 is a workpiece, 5 is a steady rest, 6 is a carriage, 7 is a carriage bed, and 20 is a cutting tool.

Generally, when loading a large and long shaft workpiece, such as a rotor shaft, on a lathe, one end is chucked by the spindle face plate 2, and the other end is supported by a steady rest 5. When the weight of the workpiece is large, steady rest support has a higher loading capacity than support at the other end by aligning the center axis, and has the effect of preventing deformation of the workpiece itself.Furthermore, the improved setup rigidity makes heavy cutting easier. It is often supported by a steady rest because it is possible.

The steady rest 5 has adjustable functions in the vertical and horizontal directions so that it can support any outside diameter, but this poses a problem.
Misalignment is likely to occur between the machine axis CM and the workpiece axis CW. Furthermore, it is difficult to measure the amount of misalignment, and in addition, when the weight of the workpiece is large, it is even more difficult to make subtle corrections.

Normally, after roughly aligning the center between the spindle face plate 2 and the steady rest 5, the workpiece 4 is rotated, the rotational whirlpool is corrected, and then idle rotation is continued to ensure that the workpiece 4 does not come out of the spindle face plate 2. After checking, the first setup is completed and the processing process begins.

Therefore, since the CM and CW of the workpiece 4 are deviated by an angle α, when the outside diameter of the workpiece is cut in a straight line with the cutting tool 20, or when the diameter of the workpiece is set at An error will occur between the diameter of the stopper 5 and the diameter.

(2) The second factor is the influence of the straightness of the machine.

FIG. 10 is an explanatory diagram showing the straightness error in a large-sized lathe, and shows the relationship between the carriage bed 7 and the workpiece 4.

In general, the larger the machine tool, the more difficult it is to adjust the straightness of the shaft for a long stroke. It changes from time to time due to reasons such as deformation of the foundation and bending and deformation of the machine due to loading of heavy objects. Therefore, for large machines.

Periodic accuracy correction is essential, but especially in the case of a lathe, if the carriage bed 7 is deformed due to a decrease in straightness as shown in the figure, the carriage 6 and the tool 2o on it When cutting the outer diameter of the workpiece, since it does not move in a straight line but moves in a meandering direction.

cause an error. Furthermore, since the amount of meandering is twice as large as the diameter, it becomes a major error factor in processing and measurement.

(3) Thirdly, there is the influence of the running movement of the machine.

Figure 11 is an explanatory diagram showing the running method on a large lathe.
The relationship between the travel of the carriage 6 and the workpiece 4 is shown. 2
1 is a scale installed in the Z-axis direction, 22-A, 22-
B indicates the read head of the scale. When play occurs between the carriage bed 7 and the carriage 6, as shown in FIG. 1, a tilt of Δθ is caused depending on the traveling direction and position. One of the factors that increases Δ0 is a decrease in the straightness of the carriage bed 7.

At this time, if the carriage 6 is tilted, an error will occur in the axial direction between the carriage movement amount H6 caused by the scale 21 attached to the Z-axis and the movement amount H by which the cutting edge of the cutting tool 20 actually moves.

The axial error increases in proportion to the distance K between the cutting tool 20 and the scale 21, but it is difficult to reduce the distance K due to the layout of one machine, and even if a slight inclination Δθ occurs,
The error in the axial direction becomes large. Therefore, no matter how accurate the scale itself is, errors will occur in processing or measurement based on the current position display.

(4) Fourthly, there is the influence of temperature changes between the scale 21 and the workpiece 4.

The scale 21, which is generally used for displaying the current position, is made of precision parts and is therefore installed in a space isolated from the outside, such as inside a bed cover. Therefore, since the workpiece 4 and the scale 21 are not in the same space, the amount of thermal deformation of the workpiece 4 differs from the amount of thermal deformation of the scale 21 depending on changes in temperature during day and night, summer and winter, and the like.

Moreover, since the relative relationship changes from time to time, even if the same workpiece 4 is processed or measured with the same machine and the same dimensions (using the current position indication by the scale 21), the results will not be the same.

This will result in an error. Furthermore, if the workpiece 4 is long, the error will be further magnified.

As mentioned above, in large lathes, due to the influence of setup of the workpiece, influence of machine precision, influence of thermal deformation due to temperature changes, etc., it is difficult to obtain a scale with high precision and high resolution according to conventional methods. Even if a current position display is used, errors will inevitably occur in processing or measurement.

[Purpose of the invention]

The present invention has been made in view of the above, and its purpose is to prevent setup errors, machine precision errors, and thermal deformation of the workpiece when machining and measuring using the current position display on a large lathe. It is an object of the present invention to provide a lathe workpiece measuring device capable of correcting all errors and measuring workpieces with high precision and efficiency.

[Summary of the invention]

The features of the present invention include a sensor for measuring X-axis movement distance of one machine, a sensor for measuring two-axis movement distance, a sensor for measuring Z-axis straightness, a sensor for measuring machine inclination, and a workpiece of each of the above sensors. an object temperature sensor for correcting measurement errors due to thermal deformation of the sensor p, an arithmetic device that stores the data of each sensor p and others and performs necessary calculations, a display device that displays the calculation results of the arithmetic device; A touch sensor attached to the machine that generates a data input signal to an arithmetic unit is provided to touch a necessary part of the workpiece, and the touch sensor is configured to detect setup errors of the workpiece, precision errors of the machine, and thermal deformation of the workpiece. The present invention is designed to automatically correct errors and measure the axial diameter and axial length of the workpiece.

[Embodiments of the invention]

Embodiments of the present invention shown in FIGS. 1 to 7 and 8.
This will be explained in detail using figures.

FIG. 1 is an overall configuration diagram showing an embodiment of a lathe workpiece measuring device of the present invention. In Fig. 1, 1 is the spindle headstock, 2 is the spindle face plate, 3 is the workpiece bed, 4 is the workpiece, 5 is the steady rest, 6 is the carriage, 7 is the carriage bed, and 8 is the laser length measurement for straightness. 9 is a Z-axis circumferential laser length measuring device, 10 is a tilt laser length measuring device, 11 is an X-axis laser length measuring device, 12 is a touch sensor that replaces the tool cutting edge, 13 is an interface for each length measuring device, 14 is a A correction interface for the laser length measuring device; 15 is an air sensor that feeds back atmospheric pressure and temperature; 16-A;

16-B is an object temperature sensor for correcting measurement according to thermal deformation of the object to be measured; 17 is an interface 1 for length measuring device;
A microcomputer stores data from 3 and performs calculations, 18 is a display interface for displaying computer correction calculation results, and 19 is a current position display device.

FIG. 2 is a bird's-eye view of FIG. In Figure 2, 10
0-A, 100-B, 100-C: are stands for the laser length measuring device, and 101 is a cover for the laser oscillator.

Setup errors and machine accuracy errors for workpiece 4 also occur in the vertical direction of the Y-axis, but by aligning various lasers and sensors at almost the same height as the workpiece axis, the measurement accuracy of errors in the Y-axis direction can be improved. The aim is to simplify the measurement system by minimizing the influence of

Next, the principle of measuring the axial diameter and axial length of the workpiece (object to be measured) 4 shown in FIG. 1 will be explained.

FIG. 3 is a diagram showing the principle of measuring the shaft diameter of the workpiece 4. The things that have the greatest influence on the shaft diameter measurement are the misalignment of the workpiece 4 due to setup errors and the left and right straightness of the machine in the Z-axis direction. Therefore, it is assumed that the workpiece 4 shown in the figure is misaligned with respect to the machine axis at an angle α, and the carriage bed 7 is meandering with a decrease in straightness. The laser length measuring devices used for shaft diameter measurement are a straightness laser length measuring device 8, a Z-axis circumference laser length measuring device 9, and an X-axis circumference laser length measuring device 11. Set the machine to the reference position (
After moving the machine to the machine origin) and resetting the laser length measuring devices 8, 9゜11, move the machine in the Z-axis direction and measure the Z-axis straightness over the entire stroke in advance. Based on the data at this time. , the straightness ΔX corresponding to an arbitrary Z-axis movement distance can be found. Next, the outer diameter dimension D1 of the predetermined reference point P of the workpiece 4, P2. D, is directly determined precisely with a micrometer or a bow gauge. next,
Move the touch sensor 12 from the machine reference position and move it to the reference point P.
1゜Touch P2 and change the amount of movement X,...,Z
, and X, Z. At this time, 2. The mechanical straightness AX, 4x, corresponding to
The relative relationship between e1I and the axis of the workpiece 4 is clarified.

Therefore, the outer diameter D at any point P0 of the workpiece 4
I is the movement tXo, Z0 and ΔXO (machine straightness) when the machine movement point touch sensor 12 is touched.
It can be found by

FIG. 4 is a schematic diagram of shaft diameter measurement. Next, a more detailed explanation will be given using FIG. 4. In Fig. 4.

The relative relationship between the straightness laser beam Bew+ and the workpiece axis is determined by the rectangle Q□, R□g R4p Qz. At this time, the distance between Qo and R-work @L-work is
It can be expressed using known measurement data of Dll Xl and Δx1, and similarly, the distance ML2 between Q2 and R2 can be expressed using data of +D21 X21 ΔX2. In addition, the distance between R1 and R7 is also the difference between the laser length measurement data z2 and Zl (Z, -Z,)
It can be expressed as Therefore, the outer diameter at any point P of the workpiece 4.

1'; II:, by proportional calculation from Ll and L2. , and the moving distance III to the point pH obtained by the touch sensor 12! It can be obtained by subtracting XI and straightness Δx0. That is, D
, is D,=2 (Lo−X.−ΔX,) −−−−−−
It is expressed as (1).

As mentioned above, if you measure the straightness of the entire Z*III stroke and the outer diameter of the reference point, D2 in advance, you can subsequently measure the outer diameter of the workpiece 4 at any position. 6 FIG. 5 is a diagram showing the principle of measuring the axial length of the workpiece 4. When determining the axial length measurement points A and Btjll'l of the workpiece 4, the touch sensor 12 is used to touch the 8 points A and Btjll'l, and the movement distance therebetween is 2A.2. If we take the difference (Z, -ZA) between them, we should be able to express the desired axial length H = (Z, -ZA). However, as shown in Figure 1, the angle QA, If a slope of Q is generated, a mere (Z, -Z,) will cause an error. Therefore, using the laser length measuring device lo for inclination and the laser length measuring device 11 for the X axis, both point A and B teno data XAlznt θ1 and X,
, Z, , θ3, the true axial length H is calculated and corrected.

FIG. 6 is a schematic diagram for measuring the axial length, and a more detailed explanation will be given below using FIG. 6. In Fig. 6, in a quadrilateral AA'B' B whose side is the desired axial length H,
AA' is XA, BB' is X.

A'B' can be found by CZm-Z, ), and the angles AA'B and BB'A' can be found from OA and θ, respectively, and the shape of the quadrilateral AA'B'B is determined. Therefore, the dimension H is this square ^A' B
' It can be calculated by geometric calculation of B.

At this time, it goes without saying that when determining XA and X, the aforementioned axis diameter measurement principle is used.

Note that in order to minimize the influence of thermal deformation of the workpiece 4 on measurement accuracy, the correction interface 14 shown in FIG.
The laser measurement data is always automatically corrected by the air sensor 15 and object temperature sensors 16-A and 16-B installed near the workpiece, so that even if the workpiece 4 undergoes thermal deformation, various laser measurement dimensions do not change. It has a simple structure.

Next, an embodiment of various processes including various calculations in the microcomputer 17 of FIG. 1 will be described using the flow and chart shown in FIG.

First, move the machine to the reference point in step 2. Next, reset each laser length measuring device to zero in step 2. Then, at step C, the straightness of the entire Z-axis stroke is measured. In addition.

The straightness measurement data at this time is shown in Fig. 8. However, since continuous data for the entire stroke cannot be obtained, measurements are taken at specified pitches, and the straightness at any position between each pitch is measured. The degree is determined by proportional calculation. Next, ■
Then, the straightness data is stored in the microcomputer 17. ■In the next step, print out the straightness data.

Also, in ■, the standard diameter is D using a micrometer, bow gauge, etc.

D2 is measured, and the measured data is entered into the microcomputer 17 in step 2. On the other hand, at (tag), Dl is touched by the touch sensor 12, and at (■), the data of X□ and Z□ is input to the microcomputer 17 by a touch signal. Also, in [phase], D8 is detected by the touch sensor 12.
At 0, the data of X,, Z, is input to the microcomputer 17 by the touch signal.
The microcomputer 17 calculates the relative position of the workpiece with respect to the reference optical axis beam using the data of ■, ■, ■, and 0. At 60, the data of each laser length measuring device is automatically corrected in response to thermal deformation of the workpiece due to object temperature. . The above is the initial data input.

Next, at 0, either shaft diameter measurement or shaft length measurement is selected. This changes the calculation software in the microcomputer 17. In the case of shaft diameter measurement, first, the machine moves to the measurement point at O, and the touch sensor 12 touches the measurement point at O.

Input Xo and Zo by a touch signal at O, calculate the straightness Δx0 of the measurement point, and further calculate the distance INI Lo from the reference optical axis to the center of the workpiece axis using the microcomputer 1.
Calculate with 7. At step o, the microcomputer 17 calculates the diameter D0 of the measurement point. In addition.

O is for adding automatic correction to the data obtained by the laser length measuring device. 0 means the workpiece axis diameter.

is displayed, and print Do with O. Hereinafter, if the shaft diameter measurement is to be repeated, return to O.

For axial length measurement, move the machine to one end A of the measurement point using ◎. At 0, the touch sensor 12 touches point A, and at 0, the touch signal causes Z&lxA.

The θ angle is input to the microcomputer 17.

The machine moves to the other end B of the measurement point at O. Touch point B with the touch sensor 12 at O, and Z by the touch signal at 0.
X,, θ, are input to the microcomputer 17.

Then, at 0, the microcomputer 17 calculates the axial length H. Note that 0 is for automatically correcting data during each measurement. Next, display the workpiece axial length H with o, and print the axial length H with . Hereafter, if the axial length measurement is to be repeated, return to O.

As described above, according to the embodiment of the present invention, data is corrected during machining or measurement using the current position display of a large lathe, so that the shaft diameter and shaft length of the workpiece 4 can be corrected. can be measured with high precision and efficiency.

Furthermore, by comparing the machine correction data with the movement data of each axis, it is possible to diagnose the accuracy of the machine itself, and it is possible to correct the machine accuracy appropriately.

Furthermore, when the machine is numerically controlled, more accurate NG control is possible by inputting correction data to the control device.

〔Effect of the invention〕

As explained above, according to the present invention, when machining and measuring are performed using the current position display on a large lathe, the setup error of the workpiece is 1. The precision error of the machine.

It is possible to perform highly accurate and highly efficient workpiece measurement by correcting all thermal deformation errors, and it is also possible to correct the degree of machine correction, and if the machine is numerically controlled,
This has the effect of allowing highly accurate NG control by inputting the correction data into the control device.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the lathe workpiece measuring device of the present invention, FIG. The figure is a schematic diagram of axial length measurement, and Figure 5 is a diagram of the principle of axial length measurement of a workpiece. Fig. 6 is a schematic diagram of axis length measurement, Fig. 7 is a flowchart showing an example of various processing including various calculations in the microcomputer of Fig. 1, and Fig. 8 is a straightness? ll'! FIG. 9 is an explanatory diagram showing a setup error of a workpiece in a large lathe. Fig. 10 is an explanatory diagram showing the straightness error in a large lathe;
FIG. 11 is an explanatory diagram showing how the large lathe runs. 4... Workpiece, 8... Laser j for straightness (1 length, 9
...Z-axis laser length measuring device, 10-mount tilt laser 711'
! Long, 11...X-axis laser length measuring device, [2...Touch sensor, 13...Interface, 14...Inner face for correction, 15...Air sensor, L6
-A, 16-13...Object temperature sensor, 12...Microcomputer (1 other person)゛-

Claims (1)

[Claims] 1. In a lathe workpiece measuring device, a sensor for measuring an X-axis movement distance of a machine, a sensor for measuring a Z-axis movement distance, a sensor for measuring Z-axis straightness, and a sensor for measuring a machine inclination. , an object temperature sensor for correcting measurement errors caused by thermal deformation of the workpiece of each of the sensors, an arithmetic device that stores data from each of the sensors and performs necessary calculations, and displays calculation results by the arithmetic device. a display device that generates a data input signal to the arithmetic unit; and a touch sensor that touches a necessary part of the workpiece attached to the machine that generates a data input signal to the arithmetic unit; A lathe workpiece measuring device characterized in that the lathe workpiece measuring device is configured to measure the shaft diameter and shaft length of the workpiece by automatically correcting thermal deformation errors of the workpiece. 2. The lathe workpiece measuring device according to claim 1, wherein the machine is a carriage that slides on a carriage bed of a lathe. 3. The lathe workpiece measuring device according to claim 1 or 2, wherein each of the measurement sensors uses a laser.