JPS6252242B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for accurately measuring the diameter of a running wire rod without contact.

In general, contact-type mechanical measuring instruments have traditionally been used to measure the diameter of stationary or slow-moving wire rods, and they maintain sufficient accuracy for practical use. . However, various difficulties arise in mechanically measuring the accurate diameter of a wire rod running at high speed, and this method is rarely used.

Therefore, a method that combines an optical method and an electrical method, which has been used conventionally, is shown in Fig. 1A.
There is a measuring device as shown below.

In this method, light from a light source 1 is converted into parallel light by a condenser lens 2, and is irradiated onto a linear body 3, which is then passed through an enlarged projection device 4 on the opposite side to a light receiving device 5,
For example, it is projected onto a photoelectric conversion device, and from the projected image on the light receiving device 5 (see FIG. 1B), a change in the amount of light in a limited field of view is converted into a current change (see FIG. 1C), The change in the diameter of the wire rod is measured from the current change using an analog display or a digital display. However, with this method, it is difficult to maintain sufficient accuracy due to changes in the amount of light from the light source and changes in the characteristics of the photoreceptor due to various causes.

The present invention eliminates such conventional drawbacks by irradiating the linear object with parallel light and enlarging and projecting it from the opposite side using an optical device. A slit parallel to the wire rod is provided so that the projected image includes the slit parallel to the wire rod, and this projected image is projected onto a television camera tube and scanned at right angles to the wire rod. The output signal of one scanning line is extracted, the ratio of the diameter of the wire rod to the slit interval is measured, and the calculation is performed using the accurate slit dimensions set in advance to determine the exact diameter of the wire rod. Regardless of changes in the amount of light or changes in the characteristics of the photoreceptor,
This allows measurements to be displayed at appropriate time intervals.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a side view of a portion of an optical device for carrying out the diameter measurement method of the present invention, and FIG. 3 is a plan view thereof, in which the same parts as in FIG. 1 are given the same reference numerals. In the figure, 6 is a parallel slit having an accurate slit width S, as shown in detail in FIG.
It is held by the holding frame 6a. Reference numeral 7 denotes a television image pickup tube, in which a parallel beam of light from a condenser lens 2 illuminates the slit 6 and the linear object 3 running approximately at its center, and a magnifying projection lens 4 clearly images the slit 6 and the linear object 3 in the same plane. TV camera tube 7
to project. 4A is an enlarged plan view showing the relative position of the slit 6 and the wire rod 3, and FIG. 4B is a side view thereof, where D indicates the diameter of the wire rod 3. FIG. 5 is an explanatory diagram of the image projected onto the television image pickup tube 7 (an enlarged projected image of the P section in FIG. 4B), where S'' indicates the enlarged slit width, and D'' similarly indicates the diameter of the wire rod.

When the image projected onto the television image pickup tube 7 is scanned perpendicularly to the line frame 3 and the output of one scanning line is extracted from the video signal that is the output signal of the image pickup tube 7, the output is shown in FIG. The signal waveform shown is obtained.
In the figure, S' corresponds to the slit width, and D' corresponds to the wire rod diameter.

As shown in FIG. 7, this signal waveform is input from the television image pickup tube 7 to a switch circuit 9 that operates at appropriate time intervals according to a switch control signal 8, and the output of one scanning line of the image pickup tube 7 is output at appropriate time intervals. The signal is taken out, amplified by the amplifying circuit 10, and D'/S' is measured by the measuring circuit 11. This D'/S' is not affected by changes in the light source 1 due to changes in the power source due to various causes, and subtle changes in the performance of the image pickup tube 7 due to changes in the power source also affect the value of D'/S'. does not affect Next, the preset slit width constant S is entered from the constant circuit 13, and the calculation circuit 12 calculates S×D'/S'=D. If necessary, the data is displayed in analog form on an analog display 16 via a DA converter 15.

In this way, there is no need to contact the running line rod 3, so it is not affected by the running speed, and by accurately measuring the width of the parallel slit 6 with accurate dimensions in advance, S×D'/S' The wire rod diameter D, which is the calculation result of =D, can be displayed accurately at appropriate time intervals without being affected by various power source fluctuations.

As explained above, according to the present invention, the factors that affect the accuracy of the measured diameter are the dimensional accuracy of the slit width, the parallel accuracy of the wire rod and the slit, the accuracy of the projected image on the image pickup tube, and the accuracy of the wire rod and the slit. The perpendicular accuracy when scanning the projected image and the resolution of the image pickup tube are completely unaffected by minute changes in the brightness of the light source or changes in performance over time of the projected image receiver, so sufficient accuracy is maintained. This has the effect of making it possible to maintain measurements on the order of μm.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of a conventional measurement method that combines an optical method and an electrical method, and A is a schematic diagram of the device;
B is a linear projection image on the light receiving device, C is a current curve diagram of photoelectric conversion by the light receiving device, FIG. 2 is a side view of the optical device portion that implements the diameter measurement method of the present invention, and FIG. 3 is a plan view thereof. , FIG. 4A is an enlarged plan view showing the relative position of the slit and the wire rod, FIG. 4B is a side view thereof, FIG. 5 is an explanatory diagram of the image projected on the TV camera tube, and FIG. 6 is the TV FIG. 7 is a diagram showing the scanning line output waveform of the image pickup tube. FIG. 7 is a block diagram showing an embodiment of the measuring method of the present invention from the television image pickup tube to the display device. 1...Light source, 2...Condenser lens, 3...
Linear body, 4... Enlargement projection device, 5... Light receiving device,
6...Slit, 7...TV image pickup tube, 8...Switch control circuit, 9...Switch circuit, 10...
Amplifying circuit, 11...Measuring circuit, 12...Calculating circuit, 13...Constant circuit, 14...Digital display, 15...D-A converter, 16...Analog display.

Claims (1)

[Scope of Claims] 1. A slit that is slightly wider than the diameter of the moving rod and parallel to the moving rod is placed in the same plane as the moving moving rod, and a parallel light beam is irradiated from one side of the moving rod to The included slit image is magnified by an optical device and projected onto a television image pickup tube, this projected image is scanned at right angles to the linear object, and one scanning line output is extracted at appropriate time intervals from the video signal and amplified. The first step is to measure the ratio D'/S' of the length D' corresponding to the diameter of the wire rod to the interval S' corresponding to the slit width expanded by the measuring circuit, and the second step is to measure The slit size S, which was accurately measured by the mechanical method, and D'/S', which were previously measured in the first step, are put into a calculation circuit to calculate the diameter of the wire rod D = S x D'/S'. A method for measuring the diameter of a running line rod, characterized in that the diameter is displayed digitally or analogously.