JPH04142409A - Apparatus for measuring diameter optically - Google Patents

Abstract

PURPOSE: To remove dirt and dusct by covering a light source and a first lens with a first tube, and covering a second lens and a measuring section with a second tube. CONSTITUTION: A light source comprising a lens 12 and diaphragms 14, 16 projects a light beam 18 to a wire 4 from a direction perpendicular thereto. The beam 18 passed through a diaphragm 20 and a measuring diaphragm 22 is converged through a lens 24 to a photoelectric measuring cell 28. Tubes 30, 32 hold the lenses 12, 14, respectively, (while covering) in the (facing) direction of the wire 4. The tubes 30, 32 are exposed to high pressure (supplied) by a pipe 34 and compressed air. Majority of the compressed air is discharged through a pipe 36 between the diaphragms 14, 16 and a pipe 38 between the diaphragms 20, 22. Remaining part of the compressed air is discharged through a pipe 40 between the lens 12 and the diaphragm 14 and a pipe 42 between the diaphragm 22 and the lens 24. Perfect removal is recognized on the circumferential wall surface at the opening of thin pipes 40, 42. Consequently, the air is jetted through a thin pipe for the lenses 12, 24 so that dust can be removed as much as possible.

Description

[Detailed description of the invention]

[0001]

[Industrial application field]

The present invention relates to a device for measuring the diameter of elongated objects. [0002]

[Conventional technology]

For example, the elongated object may be a wire or fiber. [0003] The measurement device described above must be fast and accurate, and must not affect the speed of the object passing through the device. [0004] In this type of measuring device, the object travels in a light beam region. This beam field is formed by the light source and the first lens. The area is blocked by the object passing through it and guided to the photoelectric measurement cell by the second lens. The portion of the area occluded is directly proportional to the product of the object diameter and the occluded length. If the occluded length is constant, the surface (part of the area) is proportional to the diameter of the object. [0005] Also, a laser beam that is approximately parallel to the object is used,
There is a method in which a laser beam is projected onto an object. This method is disclosed in US Pat. No. 3,851,180 and German Patent Publication No. 2,026,803, among others. [0006]

[Problem to be solved by the invention]

The photoelectric conversion process described above presents a major problem. The quantity (diameter) obtained by the above measurement is governed by the ambient temperature. Therefore, for example, a positive temperature characteristic (pos
itive temperature coeffic
Techniques are utilized to compensate for temperature, such as a light source powered through a resistor with ient=PTC). However, stable and accurate measured quantities cannot be obtained. [0007] A second problem with the photoelectric conversion process is that the intensity of the light beam does not become constant depending on the state of the object. If the object deviates from its normal course, for example if it is displaced by vibration, it will be measured as a different diameter even though there is no change in diameter. [0008] The third problem with the above photoelectric conversion process is that measurement is extremely difficult in a lumpy environment. In reality, it cannot be said that the intensity of the light beam will not decrease if there is debris. [0009] On the other hand, in the second method in which the laser beam is used, the first and second problems are solved. However, in an environment with a lot of debris (dust), it becomes difficult to measure the diameter (ie, the third problem above). The equipment utilized to solve this problem is very expensive. [0010]

[Means to solve the problem]

This invention corrects the above problems. [0011] According to the invention, an apparatus for measuring the diameter of an elongated object is provided. The above device includes a light source, a first lens, a first aperture disposed close to the first lens, a second aperture, a second lens disposed proximate to the second aperture, and a measurement device. It has a department. A first tube that covers the first lens and the first aperture, and a second tube that covers the second lens and the second aperture are respectively arranged. Means for supplying pressurized air is also connected to the first and second tubes. [0012] According to an embodiment of the invention, said means (for supplying air) are constituted by a pipe or a plurality of pipes. Each tube is connected to a pipe consisting of at least two pipes, one narrower than the other. A narrow pipe opening is located between the lens and the diaphragm. The opening of the thick pipe is located further away from the lens than the distance between the lens and the diaphragm. [0013] According to another embodiment of the invention, the apparatus changes the positional relationship between the object and the generated light beam when the object disappears from (the area of) the light beam. Means, the above object is caused by vibration etc. (area of) the above light beam
a measured quantity adjustment means for compensating for fluctuations in the measured quantity when the object disappears from the light beam (
It is equipped with a means for returning to the area of [00143] Even if the object disappears from the light beam, for example by a slight movement between two small pistons or by the arrangement of small guide wheel means, another located in the place. It is difficult to change between the two small pistons if the object is inflexible. In this case, since the optical path, that is, light source - lens - measurement stop - lens - cell is moved,
The light beam no longer deviates from the object. [0015] If the object disappears from the light beam, the light beam is no longer obstructed and the measured quantity must be O (zero). However, due to external influences, such as (fluctuations in) temperature or dust, as mentioned above (the measured amount becomes O)
It won't happen. When adjusting the measured quantity in the above device to O, different techniques are used. [0016] The first method is, for example, an electrical method, in which the intensity of the light source is changed until the measured quantity becomes O (zero). Another method is to correct by a computer program until the compensation amount of the actually measured diameter measurements stored for adjustment is O. [0017] If the object falls out of the light beam, a reference object whose diameter is already known is introduced into (in the region of) the light beam instead. In this case, a state of O equilibrium cannot be obtained, but the measured amount can be made to match the reference amount. [0018] The adjustment is very simple (takes only a few seconds) and the object is again introduced into (the area of) the light beam. [0019] The O (zero) adjustment is generated periodically depending on the surrounding conditions in which the diameter is measured. [0020] When measuring the diameter of the iron wire in an extreme environment, for example, an environment such as the outlet of a zinc tank, (measurement) errors are likely to occur, so the above-mentioned periodic adjustment becomes frequent. [0021] In addition, there is an embodiment as a measurement diaphragm that compensates for the difference in intensity of the light beam, independent of the position of the object. In the illustrated example, the configuration is such that the measurement results are not affected by the type of object. [0022]

【Example】

The present invention will be explained in more detail below based on the drawings. [0023] In FIG. 1, a device 2 for measuring the diameter of a wire 4 is shown. The device 2 is, for example, a light emitting diode (LED).
), a frosted glass 8 through which light rays emitted from the light source 6 are transmitted, and an elongated airtight chamber 10. This elongated hermetic chamber 10 is formed as long as possible in order to produce a region of the light beam that has a constant intensity in all regions in the area cross-section (of the light beam). Light beam 1 formed by lens 12 and aperture 1416
8 is irradiated from a direction perpendicular to the wire 4 . The beam 1 that has passed through the aperture 20 and the measurement aperture 22
8 is focused through lens 24 onto photoelectric measurement cell 28 . The tube 30.32 holds (covers) and (orients) the two lenses 12.24 in the direction of the wire 4, respectively. This tube 30.3
2 (provided) by pipe 34 and compressed air
Exposed to high pressure. Most of the compressed air is discharged via a pipe 36 between the throttles 14 and 16 and a pipe 38 between the throttles 20 and 22. The remaining part of the compressed air is supplied to a pipe 40 between the lens 12 and the diaphragm 14 and a pipe 40 between the diaphragm 22 and the lens 24.
2. [0024] According to the device 2 described above, it has been confirmed that a small amount of dust remains on the wall surface around the opening of the thick pipe 36.38 in the tube 30.32. On the other hand, it has been confirmed that the walls around the openings of the thin pipes 40 and 42 are completely removed. For this reason, a thin pipe is used to blow out the dust to the lens 12.24 so that as much dust as possible can be removed. [0025] In FIGS. 2A and 2B, a device for changing the relative positional relationship between the beam 18 and the wire 4 is schematically shown. According to FIG. 2(a), the wire 4
runs straight through (the area of) the beam 18 along two small guide wheels 44,46. Around the wire 4, there are two small air pistons 48°50
is located. In (a) above, the small air piston 48.50 is not pressurized. In FIG. 2(b), the small air piston 48,50 is shown with the desired pressure applied. A small air piston 48,50 causes the wire 4 to leave the travel path when it is not necessary to pass through said travel path (the normal situation in which it passes through the area of the beam 18). If the need for adjustment arises (for wire 4), it is returned to the state shown in (a). [0026] FIGS. 3A and 3B show a case where the aperture 22 is not adjusted and a case where the aperture 22 is adjusted, respectively. The concentric circles in FIGS. 3(a) and 3(b) respectively collectively capture points having substantially equal light intensities (in the cross section of the light beam 18) of equal light intensity (in the beam 18); A line connecting points) is a curve. The light intensity is slightly higher at the center than at the periphery. Therefore, the light intensity of circle 182 is
4, the light intensity of circle 184 is higher than the light intensity of circle 186, and so on (the light intensity of circles with small numbers is higher than the light intensity of circles with large numbers). )become. According to FIG. 3(a), the wire 4 in position (I) is exposed to a higher light intensity (beam) than the wire 4 in position (II). In position (I) above,
An increased diameter is measured from position (II) above. In this case, the edges 222 and 2 in the measurement diaphragm 22
24 is adjusted as shown in FIG. 3(b), the wire 4
Since the same light intensity is received regardless of the position of the light, the above-mentioned problem is eliminated. As a result, by adjusting the measurement aperture 22, the diameter can be measured even if the position of the wire 4 moves from its original position. [0027] FIG. 4 shows an example of an electrical method for compensating the amount measured under desired conditions when the intensity of the light source 6 varies. [0028] The photoelectric conversion measurement device 28 receives the light beam and generates a current i that is proportional to the intensity of the received light. This current i is converted into a voltage via an amplifier 60 and a resistor 62. This voltage is further amplified via amplifier 64. An O (zero) voltage is set via resistors 66 and 68, and an amplification constant is defined via resistor 70. The amplified voltage is directed by switch 72 to amplifier 74 and analog output cuff 6 . A portion of the amplified voltage is read into screen 78. [0029] The diameter of the wire 4 produced by the normal process is measured with switch 72 closed and switch 84 opened. If a certain condition is given by the oscillator 86 and the transistor 87, i.e. when the wire 4 deviates from the light beam (state (b) in FIG. 2), the switch 72 is opened and the switch 84 is opened. is closed. In this case, from a normal point of view, the output of the amplifier 74 should be 0 (zero). However, in rare cases, changes in the surrounding environment may occur. When the output of the amplifier 74 becomes smaller than the output of the amplifier 64, -15V is output to the amplifier 82 whose amplification constant is defined by the resistor 81. This voltage is brought to O by the Zener diode, switch 90 is closed,
Current is supplied to resistor 89. A positive pulse is supplied to counter 94 via oscillator 93. [0030] The counter 94 is connected to a digital-to-analog converter 96, and the light source 6 is supplied with a larger current (than presently) via a resistor 98. The positive pulses are applied until equilibrium is reached. The output of the amplifier 64 is O
If the output of the amplifier 82 becomes +15
V, the switch 92 is closed, and the Schmitt trigger 91 is output. Counter 94 is now supplied with current until the negative pulses balance out. In this case, a smaller current (than present) is supplied to the light source 6 via the resistor 98. [0031] The electrical scheme (circuit) further includes a resistor 100 with a positive temperature coefficient to compensate for temperature changes between the two regulating devices. [0032] Test The following is a comparison example between the measurement results obtained by the apparatus of the present invention and the measurement results obtained by the current measurement apparatus using a laser beam. [0033] The measurement rate (@degrees) was 1 time/second, and the adjustment of the device by the device of the present invention was performed every 2 minutes. The above adjustment takes several seconds (per time). [0034] Table standard diameter = 0.300 mm Device of this invention Laser beam device divergence (μ
m) 0.200~0.300 0.300~0
．． 400 value
As a result of more than 100, the measuring device of the present invention achieved an accuracy more than 8 times that of the laser beam device. The above measurement results are highly accurate when measuring the diameter of a wire that is approximately perfectly circular. Also, if the outer diameter is non-circular (measured on the wire), the wire may be inserted between two devices placed at different angles to each other. [0035]

【Effect of the invention】

According to the invention, a relatively inexpensive photoelectric conversion process and a process for compensating the measured results are utilized. Therefore, changes in the surrounding environment are compensated for at each desired time.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the device of the invention.

FIG. 2 is a schematic diagram showing an apparatus for varying the relative position of a light beam and an object;

FIG. 3 is a schematic diagram showing a measurement aperture.

FIG. 4 is a schematic diagram showing a device for adjusting the intensity of a light source.

[Explanation of symbols]

2... Diameter measuring device, 4... Wire, 6... Light source, 8... Ground glass, 10... Airtight chamber, 12...
First lens, 14.16...Aperture, 18...Light beam, 20...Aperture, 22...Measurement aperture, 24...
・Second lens, 28... Photoelectric measurement cell, 30.32.
...Tube, 34...Pipe, 36, 38.40.
42... (connection) pipe.

【Document name】

[Figure 1] drawing ↑

[Figure 2]

[Figure 3] (a) (b)

[Figure 4]

Claims (4)

[Claims] 1. A light source, a first lens, a first aperture disposed after the lens, and a first tube disposed so as to cover the first lens and the first aperture. , a second diaphragm, a second lens disposed after the diaphragm, a second tube disposed so as to cover the second diaphragm and the second lens, a measuring section, and the second lens. an apparatus for measuring the diameter of an elongated object, comprising: a tube; and means for providing pressure to the second tube. 2. The means for supplying pressure comprises a pipe means and a plurality of pipe members, and the first and second tubes are respectively comprised of the pipe means and the plurality of pipe members. The opening of the thin pipe member is arranged between the lens and the diaphragm, and the opening of the other thick pipe member extends from the lens to the lens. and the aperture, the at least two
2. The device of claim 1, wherein the device is connected by two pipe members. 3. Means for changing the positional relationship between the object and the generated light beam when the object disappears from the light beam, and when the object disappears from the light beam due to vibration or the like. 3. The device as claimed in claim 1, further comprising means for adjusting the measured quantity for compensating for variations in the measured quantity and means for returning the object to the light beam. 4. A measuring diaphragm according to claim 1, further comprising a measuring diaphragm capable of compensating the measured output independently of the position of the object even when the intensity of the light beam varies. equipment