JPS61167809A - Measuring method of internal and external diameters - Google Patents

Abstract

PURPOSE:To measure diameter size easily with high accuracy by fitting plural displacement detectors which detect the quantity of displacement perpendicular to the plane part of a detector fitting jig linearly on the plane part. CONSTITUTION:The array direction of plural displacement detectors 7' on the detector fitting jig 8 is set on the X axis and the direction of the interval between the jig 8 and a body 1 to be measured is set on the Y axis. The jig 8 is moved toward the object 1 to press the plural detectors 7' against the object 1, and measured values are obtained by the respective detectors 7'. Respective X-axial coordinates of the detectors 7' are calculated previously from the arrangement of the detectors 7'. This data set indicate coordinate values on the arcuate shape of the object in the coordinate system XY. This measured arcuate shape is considered to be part of a circle and then a processor operates the most accurate coefficient from the measurement data set and further obtains the diameter by using the coefficient.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for measuring the inner and outer diameter dimensions of circular objects (including circular arc parts) such as rotating shafts, rolls, wheels, gears, and pipes. This is an effective method that can be applied to measuring large workpieces that are several meters long.

<Conventional technology> Ensuring one-dimensional accuracy is one of the important issues in processing and assembling large workpieces, and high diameter dimensional accuracy is also required for round workpieces such as large reduction gear gears and turbine rotors. requested.

There are two methods that have been put into practical use to measure the diameter of large round workpieces.

To explain one of them based on Fig. 2, the measurement object 1
is sandwiched from both sides by jig 2, and between them, t)tD
In other words, the diameter is measured by some method)
A typical measuring device to which this method is applied is a micrometer. Another measurement method will be explained based on FIG. In FIG. 3(a), the measurement object 1
In this method, a π tape 3 is wound around the 0th round, and the diameter is determined from the circumferential length L measured by the π tape 3 as diameter=L/π (π: pi).

FIG. 3 (bNc) The friction disk 4 is the object to be measured 10
The object 1 to be measured is rotated while being pressed against the surface, and the number of revolutions n of the friction disk 4 when the object 1 to be measured 1 rotates once is measured. If the diameter d of the friction disk 4 is known, [)=dX
The diameter of the object to be measured 1 can be determined as n.

However, the former method shown in Figure sI2 has a measurable limit of about 2 meters in diameter due to constraints such as the operability of the measuring instrument and measurement accuracy. or.

A method of measuring the sag using a laser length measuring device has also been implemented, but this requires a large and highly accurate measuring device.

In addition, the latter two methods shown in FIGS. 3(a) and 3(b) are effective methods when applied to measuring the diameter of large workpieces, but 30 wraps of π tape may result in poor accuracy and friction disk 4. The reality is that there are many error factors such as slippage, making it difficult to measure diameters with high precision.

Recently, a new method has been developed that can measure the diameter of large circular objects (including arcuate parts) with high precision.

This newly developed measurement method will be explained with reference to FIG. The movable table 5 is moved to a reference surface 6 by a drive device (not shown).
A displacement detector 7 placed on the moving table 5 detects the gap between the reference surface 6 and the object to be measured 1 (more specifically, a large amount of change in the gap). Measure. Note that the amount of movement of the moving table 5 is measured by a movement amount detection device (not shown).

In FIG. 4, the moving direction of the moving table 5 is the X axis.

Consider the y-axis perpendicular to this x-axis.

The moving table 5 is moved in the direction of the arrow in the figure, and the moving distance of the moving table 5 is x1. A measurement value y1 from the displacement detector 7 at this time is obtained.

As the moving table 5 moves, "t sy□xl I 3'
m s... is obtained, and a data set within a certain movement range (
xi, yi) Find i ==1, 2, 3, -N.

At this time, data cella) (xi, yi) is the coordinate system X7
This represents the coordinate values on the arc shape of the measuring object 10 in .

If we consider that the measured arc shape is a part of a circle expressed by the well-known general formula for circles, Dataset (x
i, yi), the most probable coefficient g m ′ a
The CO value can be estimated and the diameter determined using the coefficient g s ' m ' by the arithmetic processing unit.

It can be determined by D=2X4ηT - (2).

<Problem that the invention seeks to solve> By the way, the measurement method shown in Fig. 4 is not suitable for practical use.

The following problems remained. That is, this measurement method is a method in which the movable table 5 is moved on the reference plane 6 by a drive device (not shown) to obtain the movement 11xi and the measured value yt of the displacement detector 7.

In order to obtain highly accurate measurements, a highly accurate drive device,
A reference surface 6 without ridges was required.

Conversely, backlash and reference plane 6 when driving moving table 5
If there is a ridge 9 (straightness error), the measured value y1 by the displacement detector 7 will be incorrect. However, it has been difficult to realize such a highly accurate driving device and reference plane.

In view of the above-mentioned prior art, the present invention aims to provide a method for measuring inner and outer diameter dimensions that can easily and accurately measure the diameter of a large circular object (including a circular arc portion). shall be.

Means for Solving the Problems> The present invention achieves the above object by installing a plurality of displacement detectors arranged at intervals on a flat part of a detector mounting jig for detecting displacement in a direction perpendicular to the flat part. The distance from the flat surface to the arc-shaped object to be measured is measured by each displacement detector, and the mounting position of each displacement detector and the distance measured by each displacement detector are determined. The method is characterized in that the diameter of the object to be measured is determined by calculating a plurality of pieces of data as part of a circle. In FIG. 1, reference numeral 1 indicates an object to be measured, a part of which has an arc shape.

A plurality of displacement detectors 7' are arranged in a straight line on the flat surface of the detector mounting jig 8, and measure the distance between the detector mounting jig 8 and the object to be measured 1.

In Fig. 1, the direction in which the plurality of displacement detectors 7' are arranged on the detector mounting jig 8 is the Y axis, and the direction of the distance between the detector mounting jig 8 and the measurement object l is the Y axis. Think of it as an axis.

The detector mounting jig 8 is moved in the direction of the object to be measured 1, the plurality of displacement detectors 7' are pressed against the object to be measured 1, and the measured value y1 (1=1. 2....
N) is obtained. N is the number of displacement detectors (first
In the figure, it is N; 7).

On the other hand, from the arrangement of the plurality of displacement detectors 7', the X-axis seat f'l xi (1=1', 2 e...
・aN) t' is determined in advance (for example, the X coordinate of the leftmost detector is set to X1sso, and the X coordinate of the other detector 7' is set by the amount of deviation from the leftmost detector).

The finally obtained dataset (xi, yi) i =
1°2, . . . , N represent coordinate values on the arc shape of the measuring object 10 in the coordinate system XY.

Considering that the arc shape measured here is a part of a circle expressed by the well-known general formula for circles, % formula % (1), the measurement data set ( x
l, y i) (i=i −2−”・* N), the most probable value of the coefficient gsf−C can be calculated by the method of least squares, and furthermore, the value of the coefficient g.

Using f and e, the diameter can be found as follows: D = 2 x Hachisen' e (2). The details of the equation transformation are left to you, but the coefficients g, f
, c are obtained by solving the simultaneous equations of equation (3).

where N: number of measurement data sets The method according to the invention provides -
This method measures the arcuate shape of the part to be measured in multiple measurements, and estimates and evaluates the diameter of the object from the results. Therefore,
Compared to the conventional method shown in FIG. 4, the device configuration is simple and does not require a high-precision drive device or reference surface, making it easy to put it into practical use.

Note that the distance between the detector mounting jig 8 and the measurement target 1 is
In measuring l, a problem arises due to deviations in the zero point adjustment positions of the respective displacement detectors. As a countermeasure for this, with multiple displacement detectors 7' mounted on the detector mounting jig 8, press the detectors onto a jig (for example, a straight edge) that has been guaranteed to have sufficient straightness accuracy. A method may be adopted in which the state at that time is set as yi=0 (1=1, 2, . . . , N).

In addition, although a contact-type displacement detector is shown as an example in Fig. 1, any other detector can be used as long as it can measure the distance between the detector mounting jig A8 and the object to be measured 1. is possible. In other words, optical.

The application of detectors such as eddy current type and capacitance type can be considered.

In addition, although Figure 1 shows an example of measuring the outer diameter of the object to be measured (measuring the shape of a convex arc), the method described above can also be applied as is to measuring the inner diameter (measuring the shape of a concave arc). Of course.

Incidentally, the number of displacement detectors arranged on the detector mounting jig 8 (
N) Therefore, the evaluation accuracy of the target object radius R differs. Although the details vary depending on the dimensions of the R1 detector mounting jig 8 of the object, generally N=10 to 20. [If it is done once, there is no practical problem.

<Effects of the Invention> As explained above, according to the diameter measuring method according to the present invention,
The convex and concave arc shapes of the part to be measured are measured and the diameter (radius or curvature) of the part to be measured is estimated from the results, making it easy and highly accurate to measure the diameter of particularly large workpieces. It becomes like this. Moreover, since no large-scale equipment is required for measurement, the cost required for measurement can be reduced.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one configuration of the present invention, and FIG. 2 is a diagram showing one configuration of the present invention. FIGS. 3 and 4 are explanatory diagrams of conventional examples, respectively. In the drawing. 1 is the object to be measured, 5 is a moving platform. 6 is the reference plane. 7.7' is a displacement detector, 8 is the detector mounting jig. x and y are coordinate axes.

Claims (1)

[Claims] A plurality of displacement detectors for detecting the amount of displacement in a direction perpendicular to the flat part are installed in a straight line at intervals on the flat part of the detector mounting jig, and each displacement detector detects an arc shape from the flat part. By measuring the distance to the object to be measured, and calculating the multiple data consisting of the mounting position of each displacement detector and the distance measured by each displacement detector, assuming that it is a part of a circle. A method for measuring inner and outer diameter dimensions, characterized by determining the diameter of an object to be measured.