JPH06229742A - Method for measuring curvature, outer diameter, and circularity of tubular item simultaneously - Google Patents

Abstract

PURPOSE:To allow the highly accurate simultaneous measurement of curvature, outer diameter, and circularity of a tubular item by taking advantage of common points in the measurement of curvature and outer diameter. CONSTITUTION:A tubular item 1 to be measured is supported from below at two points separated from each other in the axial direction. The item 1 is then scanned by means of a distance detector using a laser beam 7 while being rotated one or more turn in the circumferential direction. The distances L1, L2 from a reference point S on the outside of the item 1 to the opposite edges P1, P2 on the surface of the item 1 are then determined based on the scanning speed V and the scanning times T0, T1, T2. Outer diameter D and the distance L0 from the reference point S and the center 0 are determined based on the measurements L1, L2. Curvature of the item 1 is determined based on the maximum and minimum measurements of the distance L0. The circularity of the item 1 is determined based on the variation of outer diameter in the circumferential direction caused by rotation of the item 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the bending, outer diameter and roundness of a cylindrical object such as a pipe or a machine shaft.

[0002]

2. Description of the Related Art In quality inspection of long cylindrical objects such as pipes and machine shafts, it is essential to measure bending, measuring outer diameter and measuring roundness. Conventionally, as a method for measuring the bending of a cylindrical object such as a pipe or a machine shaft, there is a method in which a thread is stretched at both ends of the object to be measured by human power and a gap between the object and the thread is measured to measure the bending. As a method of automatically measuring the bend, the object to be measured is supported from below at two locations in the axial direction, and the distance from the reference point to the surface of the object to be measured is continuously measured while rotating one or more revolutions in the circumferential direction. There is one that automatically measures the bend by obtaining the difference between the maximum value and the minimum value of the distance measurement values.

Regarding the outer diameter measurement of a cylindrical object,
So far, several automatic measurement methods have been proposed and put into practical use. A method of measuring the outer diameter of a measurement object by irradiating the measurement object with a band of light such as a laser and detecting the width of the shadowed area of the measurement object with a detector on the opposite side of the measurement object. Measure the distance from two reference points facing each other with a known distance to sandwich the object to the surface of the object, and subtract the two distance measurement values from the distance between the reference points to determine the outer diameter of the object. There are ways to ask.

Further, in the roundness measurement, the outer diameters of a plurality of points in the circumferential direction of the object to be measured are measured and calculated from the fluctuation of the measured values.

[0005]

In the quality inspection of a long cylindrical object such as a pipe or a machine shaft, bending measurement,
It is essential to measure the outer diameter and the roundness. However, conventionally, the bending measurement and the outer diameter and circularity measurement are measurements in the axial direction of the measurement object, whereas the bending measurement is measurement in the axial direction of the measurement object. Therefore, the measurement is performed in another place or another device, and there is a problem in terms of the number of personnel required for the measurement, facility cost, and the like.

Therefore, according to the present invention, the curvature, the outer diameter, and the roundness can be simultaneously and highly accurately measured for a cylindrical object by utilizing the common points of the bending measurement and the outer diameter measurement. The purpose is to provide a method.

[0007]

For this purpose, a method for simultaneously measuring the bending, outer diameter, and roundness of a cylindrical object according to the present invention is such that the cylindrical object is measured from below at two axially distant circumferences. Is rotatably supported, and a reference point located outside the measurement object at one or a plurality of positions in the axial direction of the measurement object, and two straight lines parallel to the straight line passing through the reference point are used for the measurement. Two measurement points in contact with the surface of the object are set, and the distance from the reference point to the two measurement points on the surface of the object is changed by changing the position of the object in the circumferential direction for one rotation or more. The length of a perpendicular line drawn from the reference point to the two tangents is measured, and the bending, outer diameter, and roundness of the measured object are simultaneously obtained from the measured values.

[0008]

The present invention will be described with reference to the reference numerals of the embodiments.
Distances L ₁ and L ₂ from a reference point S outside the object 1 to two measuring points (edges) P ₁ and P _{2 on} the surface of the object 1 are measured. From these two distance measurement values L ₁ and L ₂ , the outer diameter D at the measurement position of the measurement object 1 and the distance L _o from the reference point S to the center O in the cross section of the measurement object 1 are obtained. As described above, the outer diameter D of the measurement object 1 and the distance L _O from the reference point S to the center O of the measurement object 1 are continuously measured while rotating the measurement object 1 in the circumferential direction for one rotation or more. taking measurement. Distance L _O
The bending of the measured object 1 can be obtained from the maximum value and the minimum value of the measured values of. Since the outer diameter of the measurement object 1 is measured by rotating the measurement object 1 in the circumferential direction, the roundness of the measurement object 1 can be obtained from the change in the outer diameter value of the measurement object 1 in the circumferential direction. As a result, the bending, outer diameter, and roundness of the measurement object 1 can be measured at the same time.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 and FIG. 2 are schematic views showing a state in which the bend, outer diameter and roundness of a pipe are measured in the embodiment.

The object to be measured 1 is supported by a turning roller 2 at two axial positions from below and is rotatable in the circumferential direction. The turning roller 2 is preferably an electric type, but may be a manual type. The turning roller 2 is provided with an angle detector 5 for detecting the rotation angle of the measurement object 1 in the circumferential direction.

The reason why the object to be measured 1 is supported at two positions in the axial direction is that if the object to be measured 1 is supported at three or more positions, the bending originally possessed by the object to be measured 1 is corrected and the bending cannot be measured accurately. As described above, the shape in the longitudinal direction of the measurement object 1 supported from below at two locations in the longitudinal direction is affected by the bending in the measurement object 1 originally, and also the influence of the vertical deflection due to the weight of the measurement object 1. I will receive it, but I will explain it later,
It is possible to accurately measure the bend originally possessed by the object to be measured 1 without being affected by the deflection due to its own weight.

The distance detector 3 is arranged so as to sandwich the measurement object 1 supported by the turning roller 2,
The signal from the distance detector 3 is processed by the data processing device 4.

3 to 5 illustrate the measuring principle of the distance detector 3.

As shown in FIG. 3, the laser light projecting portion 3a is provided.
And the light receiving portion 3b are arranged on both sides so as to sandwich the measurement object 1. Spot-shaped laser light 7 emitted from the light source 6
Is scanned in a fan shape by the polygon mirror 8, and then the lens 9
Then, the object to be measured 1 is scanned in parallel at a constant speed, and is condensed by the lens 10 on the opposite side of the object to be measured 1 and received by the light receiving element 11.

When the received signal is converted into an electric signal,
As shown in FIG. 4, the signal becomes zero only during the time when the laser is shielded by the measurement object 1. At this time, the scanning start time of the laser is T ₀ , the time when the laser starts to be shielded by the measurement object 1 is T ₁ , and the time when the shielding of the laser by the measurement object is completed is T 1.
_Set to ₂ .

As shown in FIG. 5, when the laser is scanned in parallel at a constant speed V, the laser scanning distance is obtained by multiplying the laser scanning speed by time. Therefore, the laser scanning start point is used as a reference. The distances L ₁ and L _{2 to} both edges P ₁ and P ₂ of the measured object 1 when the point S is set are L ₁ = V × (T ₁ −T ₀ ) L ₂ = V × (T ₂ −T ₀ ) Is required.

[0018] be obtained from the two distance measurements, the distance L _O from the outer diameter value D and the reference point S at a certain position axially of the measuring object 1 to the center O of the cross section, in the following equations You can D = L ₂ −L ₁ L _O = (L ₁ + L ₂ ) / 2

As the distance detector in this case, in addition to the above-mentioned method, a distance measuring method such as a triangulation method is used to sandwich the object to be measured so that the line connecting the distance detectors from both sides passes through the center of the object to be measured. Two reference points, for example, a method of measuring the distance from the measurement origin of the distance detector to the surface of the object to be measured can be used. In this case, the distance between the two reference points needs to be known in advance.

Next, a method of simultaneously performing the bending measurement of the object 1 and the outer diameter and roundness measurement using the distance detector 3 described above will be described.

The position of the distance detector 3 may be any direction in the circumferential direction of the measuring object 1 as long as the distance detecting direction connects the reference point S and the center O of the measuring object 1. In order to simplify the explanation, it is assumed that distance detection is performed in the vertical direction. Further, the installation position of the distance detector 3 with respect to the longitudinal direction of the measured object 1 is preferably arranged at a plurality of positions in the longitudinal direction when the curved object 1 has a complicated shape. If the bending of the object 1 has a simple shape, the 1 near the center of the two measurement object supporting positions in the longitudinal direction.
By arranging it in one place, it is possible to accurately determine the bend. In the following, an example in which the distance detector 3 is arranged at one place will be described assuming that the curved shape of the measured object 1 is a simple arc shape.

The measuring object 1 is supported from below by two turning rollers 2, and the measuring object 1 is rotated by one or more revolutions in the circumferential direction by the distance detector 3 by the above method. and the distance L _O from the outer diameter D and the distance reference point S to the center O of the workpiece in the cross-section continuously measured. An example of the measured value is shown in FIG.

[0023] L _O maximum value L _{O MAX} measurements, when the minimum value is L _{O MIN,} the bend M at the position of the measurement object 1 in the supported section by turning the roller 2 can be calculated using the following expression . _{M = (L O MAX -L O} MIN) / 2

When the long measuring object 1 is supported at two points from below, the bending occurs due to its own weight.
When the is rotated in the circumferential direction, it always faces the vertical direction, so that it does not affect the change in the distance L _o to the cross-sectional center of the measured object 1. The change in L _O due to rotation is due to the whirling of the measured object 1 due to bending.

Further, according to this method, since the measured object 1 is rotated in the circumferential direction to measure the outer diameter, the measured value of the outer diameter for one round in the circumferential direction of the measured object 1 is stored, By comparing them, the change in the outer diameter value of the measurement object 1 in the circumferential direction, that is, the roundness of the measurement object 1 can be easily obtained.

Therefore, with this method, it is possible to simultaneously measure the bending, outer diameter, and roundness of the object 1.

FIG. 7 shows a flow chart of the measuring operation in this embodiment.

The interval between the turning rollers 2 is set according to the length of the object 1. The measurement object 1 is placed on the turning roller 2, and the distance detector 3 is set at the midpoint between the two turning rollers 2. Start outer diameter measurement. The outer diameter is measured continuously at regular sampling intervals.
The turning roller 2 is rotated in the circumferential direction to change the outer diameter measurement position of the measurement object 1. The outer diameter is measured at this position. This rotation and the operation of measurement are performed until the measurement object 1 makes one rotation or more in the circumferential direction. The rotation angle of the measurement object 1 is detected by the rotation angle detector 5. The outer diameter measurement may be performed each time the rotation of the object to be measured 1 is stopped, or may be performed while rotating. The measured values are taken into the data processing device 4, and the data processing described above is performed to obtain the bend, the outer diameter, and the roundness.

The sampling cycle for distance measurement is about 10 ms when a laser rangefinder is used as a detector, but it is better to shorten the sampling interval as much as possible to capture a large amount of data and perform processing such as averaging. Will get better. Further, it is better in terms of accuracy that the movement pitch in the circumferential direction of the object to be measured 1 is made as fine as possible. However, the more data is taken, the longer the data processing time is, so it is necessary to set an appropriate number of data.

[0030]

As described above, according to the present invention,
At the time of quality inspection of long cylindrical objects such as pipes and machine axes, the bending and outer diameter and roundness of the measured objects, which were conventionally measured at different places or individual devices, can be measured at the same time. It is possible to measure with high accuracy, and it is possible to greatly reduce the number of personnel required for measurement and equipment costs.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a state in which the bending, outer diameter, and roundness of a measurement object are measured in an example of the present invention.

FIG. 2 is a schematic side view of the above embodiment.

FIG. 3 is a configuration diagram of a main part for explaining a measurement principle of the distance detector in the above embodiment.

FIG. 4 is a graph showing a signal level at the time of receiving a laser, which explains the measurement principle.

FIG. 5 is a diagram showing a laser scanning state of a main part for explaining the measurement principle.

FIG. 6 is a graph showing a change in the distance from the distance measurement reference point to the center of the measurement object according to the rotation of the measurement object in the above example.

FIG. 7 is a flowchart of a measurement operation in the above embodiment.

[Explanation of symbols]

 1 Measured Object 2 Turning Roller 3 Distance Detector 3a Light Emitting Section 3b Light Receiving Section 4 Data Processing Device 5 Angle Detector 6 Light Source 7 Laser Light 8 Polygon Mirror 9 Lens 10 Lens 11 Photosensitive Element

Claims (1)

[Claims] 1. A cylindrical measurement object is rotatably supported from below at two axially distant locations, and at the outside of the measurement object at one or a plurality of positions in the axial direction of the measurement object. A reference point located at, and two measurement points at which two straight lines parallel to a straight line passing through the reference point are in contact with the surface of the object to be measured, and the position of the object to be measured in the circumferential direction for one rotation or more is set. While changing, the distance from the reference point to the two measurement points on the surface of the object to be measured is measured as the length of a perpendicular line drawn from the reference point to the two tangent lines, and from the measured value, the bending of the object is measured. A method for simultaneously measuring the bending of a cylindrical object and the outer diameter and the roundness, which is characterized by simultaneously obtaining the outer diameter and the roundness.