JPS58108406A - Measuring apparatus for outside diameter of steel pipe - Google Patents

Abstract

PURPOSE:To measure the outside diameter of a steel pipe in an on-line manner, by providing an outside-diameter measuring apparatus with a screw mechanism having thread parts different in pitch for moving phtodetectors disposed opposite to a projector in opposite directions according to the diameter of a steel pipe to be measured. CONSTITUTION:The pitch of a thread part 11 for moving one detector 2a is made large, while the pitch of a thread part 12 for moving the other detector 2b is made small, and the thread parts are opposite in thread direction to each other. If the projection angle of light from a projector 1 is theta with respect to a fixing rest 5 and the radius of a steel pipe X is (r), the distances between the positions where the detectors 2a and 2b are set in measuring the steel pipe outside diameter on one hand and a reference line alpha on the other are represented by (1+costheta)r and (1-costheta)r, respectively. Therefore, if a ball screw 10 is employed having the thread parts 11, 12 with a pitch ratio of (1+costheta):(1-costheta), it is possible to set the detectors 2a, 2b at their respective predetermined reference positions by means of a single driver 4 at all times even if the diameter of the steel pipe X to be measured changes and the central position thereof changes.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a steel pipe outer diameter measuring device Y-0. What is meant by keeping the product within a predetermined external clearance value in a steel pipe production line i?
This is extremely important for quality assurance. For this reason, a device to measure the outer diameter online - IjXR - has been installed, and it has become essential in the manufacturing process. An example is shown in Figure 1. In the figure, (1) is a light projector (2) (2) is a photodetector, and these are installed so as to sandwich the wrinkle measuring steel pipe between them.

In order to satisfy the required accuracy of this measuring device (usually ±0.1■), the photodetector (2) must have a resolution of about 20 Fm, but the visual field of the detector (2) is usually Since 2000 times is ll[, the field of view F with a resolution of 20 μm is
It becomes i40■.

The measurable outer diameter range required for this is good.
Since the distance is approximately 410 m, move the detector (2) (2) to the reference position according to the outer diameter of the steel pipe to be measured (3) and determine the outer diameter #1 using the reference value + measured value. There is/
The detector position shown by the solid line in the figure is the position when measuring the outer diameter of the maximum diameter steel pipe to be measured (A), and the dashed line is the minimum diameter Mil.
This is the position when measuring the outer diameter of fixed steel pipe products.

The mechanism for moving the two-piece detector (2) (2) is as follows: To ensure accuracy, two detectors (2 bars 2) are moved into one drive unit by means of a symmetrical pole screw (3). (4)
A mechanism is adopted that moves the K and K at the same time.

However, the so-called symmetrical ball screw (3), in which screws with the same bit length are formed in opposite directions on the left and right, can be used only when the center of the steel pipe remains the same even when the outer diameter changes, i.e. This is only a line in which the conveyor stand can be moved up and down according to the outer diameter size, and in a normal line with a fixed stand type, it is necessary to change the moving distance of the three detectors individually according to the outer diameter. In such cases, such measuring devices cannot be used.

To solve this problem, there is a method of attaching an independent moving device to each of the two detectors and moving them individually, or a method of arranging several fixed detectors and moving only one of them. However, the former method is disadvantageous in terms of cost, and also has the disadvantage that the measuring device becomes larger in proportion to the number of drive mechanisms, resulting in spatial restrictions on the installation location. There are also problems such as being disadvantageous in terms of maintenance. Similarly, in the case of a casual user, there are problems in that the price is disadvantageous, the entire detector becomes large, and there are spatial restrictions on the setting location.

The present invention has been made to overcome the drawbacks of the conventional measuring devices as described above, and provides a comparatively inexpensive and compact measuring device that can be used even on lines with fixed mounts.1. This is what we are trying to do.

An embodiment of the outer diameter measuring device according to the present invention will be described below with reference to FIGS. 2 to 5.

In the figure, (1) is a floodlight, (2) a light detector, (4) is a drive device, (5) is a fixed frame, and (11 is a ball screw. Photodetector (2). (2) is a one-way Two pieces are arranged for the outer diameter #1 of the constant, and are set to the reference position by the drive mechanism (4) It takes 1 N! to move the ball screw (A) to the position indicated by the -AN line by rotating the ball screw (A) by the drive mechanism (4).

Therefore, in the present invention, the ball position is configured as shown in FIG. 3. That is, the screw that moves one of the detectors (2A)! ! The pitch of 1106 is increased, and the screw part (2b) that moves the other detector (2b) is
2) The pitch is made small, and the screw directions are opposite to each other.

The pitch ratio of threaded portions a1 and (6) can be found from FIG. Now, fix the projection angle from the projector (1) using the mounting frame (5).
) If θ is K for K, and r is the radius of the steel pipe, then the distances between the position where detectors "C2a) and (2b) are set and the reference line -) when measuring the outside diameter of the steel pipe are, respectively. As shown in the figure, K(1+cosθ)re (1-eos#)r
・Here, let's graph the relationship with the radius r with the amount of movement as y.The detector (2a) is y=(1+cosθ)
r, detector (2b) is y==-(1-cos #)
r・Therefore, the screw 1lscl of the detector (2a)
I and detector (2b) O thread Its (1 pitch ratio is (
1+coa #): (1-eosθ) If a ball screw α1 having a threaded portion Q10 with the above pitch ratio is used, the diameter of the steel pipe to be measured can be determined by one drive device (4). The detector (2m) (2b) can be constantly installed at a predetermined reference position tK even if the center position changes. As shown in FIG. 1, the conventional device is the same in terms of simplicity of construction and size, and can be made into a small and inexpensive device.

As explained above, the steel pipe outer diameter measuring device according to the present invention can also be used in the case of an expansion and fixing frame line, and the device can be made compact and inexpensive due to its relatively simple configuration. There are other effects.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional measuring device, Fig. 2 is a block diagram showing an embodiment of the measuring device according to the present invention, Fig. 3 is an enlarged view of a ball screw, and Fig. 4 is a block diagram of a conventional measuring device. The explanatory diagram, FIG. 5, is a graph showing the relationship between the steel pipe radius r and the detector movement amount y. 5)... Fixed frame, QQ... Ball screw, (1102... Threaded part. WIT applicant Nippon Kokan Co., Ltd.

Claims (1)

[Claims] A floodlight that emits light toward the steel pipe to be measured from a predetermined angle θ direction with respect to the mount WJK of the steel pipe to be measured, and two or more photodetectors installed on the opposite side of the floodlight with the steel pipe to be measured sandwiched between them. The photodetector is moved in the opposite direction according to the @ of the steel pipe to be measured (1+cos #): (1-cos
#kIII of a steel pipe characterized by having a screw mechanism having threaded portions with different pitches in the ratio of #kIII
l-determining device.