JP2013036913A - Length measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a length measurement device capable of accurately measuring a length of a long material under conveyance.SOLUTION: The length measurement device 1 includes a passage detection unit 3 arranged on a conveyance line 2 at an upstream side in the conveyance direction, a position detection unit 4 arranged at a downstream side in the conveyance direction, a calculation unit 5 for calculating the length of a long material, and a control unit 6 for controlling the calculation unit 5 and the like. The passage detection unit 3 includes a plurality of sets of passage light projection units 31 projecting light to the conveyance line 2 and passage light reception units 32 respectively arranged facing the passage light projection units 31 across the conveyance line 2. The position detection unit 4 includes a light projection unit 41 that projects light substantially perpendicular to the conveyance direction toward the conveyance line 2 and scans the conveyance line with the light in parallel with the conveyance direction, and a light receiving unit 42 arranged facing the light projection unit 41 across the conveyance line 2 and receiving the light from the light projection unit 41.

Description

  The present invention relates to a length measuring device. In particular, the present invention relates to a length measuring apparatus that can accurately measure the length of a long material being conveyed.

Conventionally, as a device for measuring the length of a long material such as a steel pipe, steel bar, or die steel on a conveyance line during conveyance, there is a device that presses a roller against the long material and measures the length from the number of rotations of the roller. Are known. However, in such an apparatus, a large error occurs due to slippage between the roller and the long material.
As a measuring apparatus for preventing such an error, as shown in FIG. 1, a light receiving unit including a lens and a plurality of light receiving elements arranged in the transport direction, and a light source are arranged in the transport direction across the transport line. A measuring device is known that is provided in a direction orthogonal to each other so that a material on a transport line passes between a light receiving unit and a light source (see Patent Document 1).
In this measuring apparatus, when the rear end of the long material passes through a predetermined position, the position of the front end of the long material is detected from the position of the light receiving element that receives light from the light source, and the detected position of the front end The length of the long material is calculated from the predetermined position through which the rear end has passed. However, in such an apparatus, even if the position of the front end of the long material in the transport direction is the same, the pass line varies, and the distance from the light receiving unit varies in the direction perpendicular to the transport direction. If it fluctuates between positions P1 and P2, the position of the light that passes through the front end of the long material and is received by the light receiving element fluctuates between positions Q1 and Q2. Therefore, the position of the detected front end varies, and a large error occurs in the length of the long material to be measured.

  Moreover, a measuring apparatus provided with a plurality of optical sensors for detecting the passage of the end of the long material in the transport direction is known (see Patent Document 2). In this measuring apparatus, the position of the front end of the long material when any one of the light sensors detects the passage of the rear end of the long material, which light sensor is between which light sensor and the front end. It is calculated from the information and the estimated transport speed of the long material. Then, the length of the long material is calculated from the calculated position of the front end and the position of the optical sensor detecting the rear end. The estimated transport speed is calculated from the time passing through the plurality of optical sensors. However, in such an apparatus, since the estimated conveyance speed is used for calculating the length of the long material, the accuracy of the estimated value of the conveyance speed must be increased in order to improve the measurement accuracy. In order to increase the accuracy of the estimated value of the conveyance speed, the number of photosensors must be increased. If the number of photosensors increases, there is a problem that it takes time to maintain the photosensors.

Also, a measuring device is known that includes two detectors that detect the passage of a front end and a rear end of a long material and a laser Doppler velocimeter (see Patent Document 3). In this measuring apparatus, the length of the long material is calculated from the time when the front end and the rear end of the long material are detected and the conveyance speed of the long material measured by the laser Doppler velocimeter. Since this measuring apparatus can measure the length of a long material with high accuracy, it is widely used for measuring the length of a long material.
The laser Doppler velocimeter projects laser light on a long material, and detects the conveyance speed by the reflected light. However, the amount of light received by the light receiving unit is large depending on the distance from the light projecting unit and the light receiving unit to the long material, the angle between the surface of the long material that reflects the laser light and the optical axis of the laser light, and the like. fluctuate. If the amount of received light decreases, there is a possibility that the conveyance speed cannot be measured.
Therefore, when the long material is a steel pipe or steel bar, it is measured accurately by adjusting the distance from the laser beam projecting part and the light receiving part to the long material according to the outer diameter of the steel pipe or steel bar. be able to.
However, when the long material is a shape steel, there are various cross-sectional shapes, such as H-shape steel, angle-shape steel, and Z-shape steel, and the inclination of the surface that reflects the laser beam changes depending on how it is placed, so the distance to the shape steel In addition to adjusting the laser beam, there is a problem that the positions of the light projecting part and the light receiving part of the laser light must be adjusted in accordance with the inclination of the surface of the die steel that reflects the laser light. In FIG. 2, the cross section of each shape steel is shown. In particular, when a plurality of cross-sectional shape steels are transported to the same transport line, it takes time since the positions of the laser light projecting part and the light receiving part must be adjusted in accordance with the cross-sectional shape of the steel mold.

JP 51-32659 A JP 11-237214 A Japanese Patent Laid-Open No. 62-240805

  The present invention has been made to solve such a problem of the prior art, and an object of the present invention is to provide a length measuring device that can accurately measure the length of a long material being conveyed. .

  The inventors can accurately adjust the length of the long material during the conveyance even if the pass line of the long material fluctuates or the long material having various cross-sectional shapes is conveyed on the same conveyance line. The length measuring device that can be measured was examined. As a result of the investigation, the position of the end of the long material is detected by the light orthogonal to the conveyance line, so that it is not affected by fluctuations in the pass line of the long material or the cross-sectional shape of the long material. It was found that the length can be measured with high accuracy.

  The present invention has been completed on the basis of the results of the above-described investigation by the present inventors. That is, in order to solve the above-mentioned problem, the present invention is a length measuring device that measures the length of a long material conveyed in a conveyance line during conveyance, and includes an upstream side and a downstream side in the conveyance direction. A passage detection unit that is provided on any one side of the long material and detects that the end of the one side of the long material passes through a predetermined position; and the other side of the upstream side and the downstream side in the transport direction A position detection unit that detects a position of the other end of the long material at the time of passage detected by the passage detection unit, and the other side of the long material detected by the position detection unit A calculation unit that calculates the length of the long material from the position of the end of the sheet and the predetermined position, and the position detection unit projects light substantially orthogonal to the conveyance direction toward the conveyance line. A light projecting unit that scans the light in parallel with the transport direction, the light projecting unit, and the transport line A light receiving unit that faces and sandwiches the light from the light projecting unit, and the passage detection unit detects that the one end of the long material has passed the predetermined position. And detecting the position of the other end of the long material from the position where the light received by the light receiving portion of the parallel scanned light is blocked by the long material and the position where the light is not blocked by the long material. A length measuring device is provided.

In the present invention, the term “substantially orthogonal” includes not only the case of being completely orthogonal, but also including the orthogonality that fluctuates within a range that does not affect the measurement accuracy of the length required for the length measuring device of the present invention. It represents.
According to the present invention, since the position of the end of the long material is detected by the light projected from the light projecting portion so as to be substantially orthogonal to the transport direction and parallel scanned in the transport direction, the long material pass line Even if the position of the long material fluctuates in the direction perpendicular to the conveyance direction or the cross-sectional shape of the long material changes variously, the position detection unit detects the end of the long material. The position does not change. Therefore, the length of the long material can be accurately measured.

  Preferably, the light receiving unit includes a light guide extending in a transport direction and a photodetector provided on one end side of the light guide, and a part of light incident on the light guide from the light projecting unit is the light guide. Guided to a photodetector.

  According to such a preferable light receiving portion, the light guide rod can easily change the length in the carrying direction, and therefore the range in the carrying direction in which the light receiving portion can receive light can be easily lengthened.

  In addition, the present invention is a length measuring device that measures the length of a long material conveyed in a conveying line during conveyance, and is provided on either the upstream side or the downstream side in the conveying direction. The passage detection unit that detects that the end of the one side of the long material passes through a predetermined position, and is provided on the other side of the upstream side and the downstream side in the transport direction, and the passage detection A position detection unit that detects a position of the other end of the long material at the passage time detected by the unit, a position of the other end of the long material detected by the position detection unit, and the predetermined position A calculation unit that calculates the length of the long material from the position of the light source, the position detection unit projecting light toward the transport line, and the light projecting unit across the transport line An imaging unit with a telecentric lens provided opposite to the imaging unit, the imaging unit The optical axis of the telecentric lens is provided so as to be substantially orthogonal to the transport direction, and the transport is detected when the passage detection unit detects that the one end of the long material has passed the predetermined position. The other end of the long material conveyed through a line is imaged, and the position detection unit detects the position of the other end of the long material from a captured image captured by the imaging unit. A length measuring device is provided.

In the present invention, the term “substantially orthogonal” includes not only the case of being completely orthogonal, but also including the orthogonality that fluctuates within a range that does not affect the measurement accuracy of the length required for the length measuring device of the present invention. It represents.
Here, the telecentric lens will be described. FIG. 3 is an explanatory diagram of a telecentric lens.
In the telecentric lens, a light beam emitted from a subject parallel to the optical axis is taken into an optical system. Therefore, even if the distance between the subject and the optical system changes, the size of the image does not change. FIG. 3A is a diagram illustrating a relationship between a subject and an image with a conventional lens. Even if the subject is the same size, the image of the subject far from the lens becomes smaller. FIG. 3B is a diagram showing the relationship between the subject and the image in the telecentric lens. Even if a subject of the same size is located at a position far from the telecentric lens, the image has the same size.
FIG. 3C is a diagram showing an optical path in a conventional lens. In the conventional lens, the imageable range can be represented by an angle viewed from the center of the lens. This angle is called the angle of view and is defined by the angle between the principal rays.
FIG. 3D is a diagram showing an optical path in the telecentric lens. The telecentric lens is an optical system arranged so that principal rays parallel to the optical axis pass through the focal point, and the angle of view is 0 °. Therefore, the image does not change even if the distance between the subject and the telecentric lens changes.

  According to the present invention, the light that is substantially orthogonal to the transport direction is selected from the light projected from the light projecting unit by the telecentric lens, and a captured image is formed by the selected light. And since the position of the end of the long material is detected from the captured image, even if the pass line of the long material fluctuates and the position of the long material fluctuates in the direction orthogonal to the conveying direction, Even if the cross-sectional shape of the material changes variously, the position of the end of the long material detected by the position detection unit does not change. Therefore, the length of the long material can be accurately measured.

  According to the present invention, the length of a long material being conveyed can be accurately measured.

FIG. 1 is a configuration diagram of a part of a conventional length measuring apparatus. FIG. 2 is a cross-sectional view of the mold steel. FIG. 3 is an explanatory diagram of a telecentric lens, FIG. 3 (a) is a diagram showing the relationship between a subject and an image in a conventional lens, and FIG. 3 (b) is a diagram of the subject and image in a telecentric lens. FIG. 3C is a diagram showing an optical path in a conventional lens, and FIG. 3D is a diagram showing an optical path in a telecentric lens. FIG. 4 is a configuration diagram of the length measuring apparatus according to the first embodiment. FIG. 5 is a transition diagram of the light receiving state of the light receiving sensor and the light receiving unit, and FIG. 5A is a transition diagram of the light receiving state of the light receiving sensor and the light receiving unit when there is no front end of the die steel in the detection range, FIG. 5B is a transition diagram of the light receiving state of the light receiving sensor and the light receiving unit when the front end of the die steel is within the detection range. FIG. 6 is a flowchart of a measuring method using the same length measuring device. FIG. 7 is a configuration diagram illustrating another example of the light receiving unit. FIG. 8 is a configuration diagram of a length measuring apparatus according to the second embodiment. FIG. 9 is an image obtained by binarizing the captured image captured by the imaging unit. FIG. 10 is a flowchart of a measuring method using the same length measuring device.

(First embodiment)
Hereinafter, the length measuring apparatus 1 according to the first embodiment of the present invention will be described with reference to the accompanying drawings as appropriate.
FIG. 4 is a configuration diagram of the length measuring device 1 and is a view of the transport line 2 as viewed from above.
The length measuring device 1 measures the length of the long material conveyed on the conveyance roll 21 of the conveyance line 2 during conveyance. The long material is conveyed along the conveyance line 2 in the direction of arrow A. There is no restriction | limiting of a material or a cross-sectional shape in a long material, For example, a steel pipe, a bar steel, a shape steel, a flat steel etc. are mentioned, However, In this embodiment, the length measuring apparatus 1 is demonstrated taking a shape steel as an example.
The length measuring device 1 includes a passage detection unit 3 provided on the upstream side in the conveyance direction of the conveyance line 2, a position detection unit 4 provided on the downstream side in the conveyance direction, and a calculation unit that calculates the length of the long material. And 5. Moreover, the length measuring apparatus 1 is provided with the control part 6 which controls the calculating part 5 grade | etc.,.
The length measuring device 1 detects the position of the front end, which is the downstream end when the rear end, which is the upstream end of the shape steel K, has passed through the passage detection unit 3, and detects the length of the shape steel K. Measure the thickness.

The passage detection unit 3 detects that the rear end of the shape steel K passes a predetermined position. The passage detection unit 3 includes a plurality of passage light projecting units 31 that project toward the transport line 2 and a plurality of passage light receiving units 32 that are provided to face the passage light projecting unit 31 with the transport line 2 interposed therebetween. It is equipped with a set. The passage light projecting unit 31 is, for example, a laser diode, and the passage light receiving unit 32 is, for example, a photodiode. In the present embodiment, the number of sets of the passage light projecting unit 31 and the passage light receiving unit 32 is n. The set of the passage light projecting unit 31 and the passage light receiving unit 32 is referred to as a passage detection set 33, and the passage detection set 33 provided on the most upstream side in the transport direction is referred to as a first passage detection set 33. The passage detection set 33 provided on the downstream side next to the set 33 is referred to as a second passage detection set 33, and hereinafter, similarly referred to as a third passage detection set 33 or the like.
Each passage detection set 33 is provided at a predetermined interval in the transport direction. This predetermined interval is, for example, 2 m.
The passage light projecting unit 31 and the passage light receiving unit 32 are provided such that a straight line connecting the both is substantially orthogonal to the transport direction. The passage detection set 33 is arranged so that the light projected from the passage light projecting unit 31 and received by the passage light receiving unit 32 passes through a predetermined position where the passage of the rear end of the steel plate K is desired to be detected.
The passage detection unit 3 includes a signal transmission unit 34 that is connected to each passage light receiving unit 32 and transmits a passage signal of the rear end of the steel plate K to the control unit 6. The signal transmission unit 34 changes the predetermined detection state of each passage detection set 33 when each passage light receiving unit 32 changes from a state where it does not receive light from each passage light projecting unit 31 to a state where it receives light. Assuming that the rear end of the steel plate K has passed through the position, a passing signal is transmitted to the control unit 6.
For example, if the conveyance speed of the steel shape K is about 4 m / s, a passage signal is sent from the passage detection set 33 at intervals of about 0.5 seconds.

The position detection unit 4 detects the position of the tip of the shape steel K when the passage detection unit 3 passes the predetermined positions of the rear end of the shape steel K.
The position detection unit 4 projects light substantially orthogonal to the transport direction toward the transport line 2, and projects the light projecting unit 41 that scans the light in parallel with the transport direction, and the light projecting unit 41 and the transport line 2. A light receiving unit 42 that receives light from the light projecting unit 41 is provided so as to face each other in the horizontal direction.
The light projecting unit 41 includes a semiconductor laser 411 that emits laser light (light) L1, a polygon mirror 412 that reflects the laser light L1 while rotating, a plane mirror 413, and a parabolic mirror 414. The polygon mirror 412 rotates in the direction of arrow B.
The laser beam L1 emitted from the semiconductor laser 411 is reflected in the order of the polygon mirror 412, the plane mirror 413, and the parabolic mirror 414. The parabolic mirror 414 is curved so that the laser beam L1 reflected by the plane mirror 413 is reflected in a direction substantially perpendicular to the transport direction.
Accordingly, the laser beam L1 emitted from the semiconductor laser 411 is projected onto the conveyance line 2 so as to be substantially orthogonal to the conveyance direction, and the polygon mirror 412 is rotated. To scan in parallel. A detection range for detecting the position of the tip of the steel plate K is provided inside the range in which the laser beam L1 is scanned in parallel. This detection range must be wider than the interval between the passage detection sets 33.
The light projecting unit 41 includes a light receiving sensor 415 that receives the laser light L1 reflected by the flat mirror 413, and the calculation unit 5 is arbitrarily set based on the time when the light receiving sensor 415 receives the laser light L1. The scanning position of the laser beam L1 at the time is calculated. The light receiving sensor 415 is, for example, a PIN photodiode.

The light receiving unit 42 has a light receiving range so that the position detection unit 4 covers the detection range in which the position of the front end of the steel plate K is detected in the transport direction. When the mold steel K is not present at the scanning position of the laser beam L1, the laser beam L1 is received by the light receiving unit 42. However, when the mold steel K is present at the scanning position of the laser beam L1, the laser beam L1 is blocked by the mold steel K. 42 does not receive light. The light receiving unit 42 transmits to the control unit 6 whether or not the light receiving state is receiving light from the light projecting unit 41.
The light receiving unit 42 may have any configuration as long as it detects whether or not the laser beam L1 is projected into the light receiving range. For example, the light receiving unit 42 includes a plurality of photodiodes arranged in the transport direction. 421. When any one of the photodiodes 421 receives light from the light projecting unit 41, the control unit 6 assumes that the light receiving unit 42 is in a light receiving state, and any of the photodiodes 421 also receives light from the light projecting unit 41. When light is not received, the light receiving unit 42 is not in a light receiving state.
As another example of the light receiving unit 42, a configuration including a parabolic mirror that condenses the laser light L1 and a photodiode that detects the condensing laser light L1 may be employed.

Determination of whether or not the front end of the shape steel K is within the detection range of the position detection unit 4 and a method for detecting the position of the front end when the front end is within the detection range will be described.
5A is a transition diagram of the light receiving state of the light receiving sensor 415 and the light receiving unit 42 when the front end of the shape steel K is not within the detection range, and FIG. 5B is a front view of the shape steel K within the detection range. It is a transition diagram of the light-receiving state of the light-receiving sensor 415 and the light-receiving unit 42 when there is a light. The state where light is received is turned on, and the state where light is not received is turned off. When parallel scanning is performed at 1 kHz, the interval between ON and ON of the light receiving sensor 415 is 1 msec.
A case where there is no front end of the shape steel K within the detection range will be described.
The light receiving sensor 415 is turned on when the laser beam L1 scanning the parabolic mirror 414 is received. The light receiving unit 42 is on while the laser beam L1 scans the detection range. The portion where the light receiving unit 42 is turned off in the drawing is when the laser beam L1 is scanning outside the range where the light receiving unit 42 can receive light.
Next, the case where the front end of the shape steel K exists in the detection range will be described.
The light receiving sensor 415 is turned on when the laser beam L1 scanning the parabolic mirror 414 is received as in the case where the steel plate K is not in the detection range.
And since the light-receiving part 42 is scanning the laser beam L1 from the front to the back of the conveyance direction, when the laser beam L1 is scanning downstream from the front end of the steel plate K, that is, parallel scanning is performed. When the laser beam L1 is received by the light receiving portion 42 at a position where it is not blocked by the steel mold K, the laser beam L1 is on. When the laser beam L1 is scanning upstream of the front end of the steel mold K, that is, parallel scanning is performed. When the received light of the laser beam L1 at the light receiving portion 42 is at a position where it is blocked by the steel mold K, the laser light L1 is turned off and changes from on to off at the front end of the steel mold K.

Accordingly, when the light receiving state of the light receiving unit 42 remains on while the laser beam L1 scans the detection range, it is determined that there is no front end of the shape steel K within the detection range, and the laser beam L1 is detected. If the light receiving state of the light receiving unit 42 is changed from on to off while scanning the range, it is determined that the front end of the shape steel K exists within the detection range.
When the front end of the steel plate K is within the detection range, the time difference between the time when the light receiving state of the light receiving unit 42 changes from on to off and the time when the light receiving sensor 415 receives the laser beam L1 is obtained. The position of the front end of the shape steel K is obtained from the time difference. In order to obtain the position of the front end of the shape steel K from the time difference between the time when the light receiving state of the light receiving unit 42 changes from on to off and the time when the light receiving sensor 415 receives the laser light L1, the laser light L1 is received by the light receiving sensor 415. The relationship between the time after the light is received and the scanning position of the laser beam L1 on the conveying line 2 is obtained from calculation or test, and the position of the front end of the steel plate K is obtained from the obtained relationship and the detected time difference.

Next, a method for detecting the length of the shape steel K using the length measuring device 1 will be described.
FIG. 6 shows the flow of the measurement method.
First, the control unit 6 sets a variable m indicating the number of times the passage detection unit 3 has detected the passage of the rear end of the shape steel K to 1 (step 1, hereinafter referred to as S1).
When conveyance of the shape steel K is started and a passing signal is received from the signal transmission unit 34 (S2), the control unit 6 receives light in the light receiving sensor 415 and the light receiving unit 42 in one scan at the time of scanning of the next laser light L1. Is stored in a storage unit (not shown) together with the variable m (S3).
Then, it is determined whether or not the variable m is n or more (S4). If the variable m is not n or more, 1 is added to the variable m (S5), the process returns to S2, waits for the next passing signal, and repeats S2 to S5.
If the variable m is greater than or equal to n in S4, the calculation unit 5 is caused to calculate the length of the shape steel K, assuming that the rear end of the shape steel K has passed through the location of the passage detection set 33 provided on the most downstream side.
The calculation unit 5 obtains data in which the front end of the shape steel K is detected within the detection range from the on / off transition data of the light receiving state in the light receiving sensor 415 and the light receiving unit 42 stored in the storage unit in S3. Search for. As described above, this search is determined based on whether or not the light receiving state of the light receiving unit 42 is changed from on to off while the laser beam L1 scans the detection range (S6).
And if the data in which it is detected that the front end of the shape steel K exists in the detection range are searched, the position of the front end of the shape steel K in the data is obtained. As described above, the position of the front end is obtained from the time difference between the time when the light receiving state of the light receiving unit 42 changes from on to off and the time when the light receiving sensor 415 receives the laser light L1 (S7).
Next, the position of the rear end of the shape steel K when the front end of the shape steel K is within the detection range is obtained as follows. The passage detection set 33 through which the rear end has passed when the position of the front end of the shape steel K is detected is obtained by the variable m stored together with the data when the front end of the shape steel K is within the detection range. For example, if the variable m is 1, it is the first passage detection set 33, and if the variable m is 2, it is the second passage detection set 33. Then, the predetermined position where the obtained passage detection set 33 detects the passage of the rear end of the shape steel K is the position of the rear end of the shape steel K (S8).
Next, the calculating part 5 calculates the length of the shape steel K from the position of the front end and the position of the rear end of the obtained shape steel K (S9).

According to the length measuring device 1 of the present embodiment, the position of the front end of the long material is detected by the light projected from the light projecting unit 41 so as to be substantially orthogonal to the transport direction and scanned in parallel in the transport direction. Therefore, even if the pass line of the long material fluctuates and the position of the long material fluctuates in a direction orthogonal to the conveying direction, or the cross-sectional shape of the long material changes variously, the position detector 4 Does not change the position of the front end of the long material detected. Therefore, the length of the long material can be accurately measured.
In particular, in the present embodiment, the light projecting unit 41 and the light receiving unit 42 are arranged in the horizontal direction so that the position of the front end of the long material can be easily detected, but the laser light L1 from the light projecting unit 41 is generated. Since it is almost orthogonal to the transport direction, the length of the long material is accurately measured even if the path line of the long material fluctuates and the distance between the light projecting unit 41 and the light receiving unit 42 and the long material fluctuates. it can.

In the above-described embodiment, the example in which the light receiving unit includes a plurality of light receiving elements has been described. However, the configuration of the light receiving unit is not limited to the above example, and for example, the following configuration may be used.
FIG. 7 is a configuration diagram illustrating another example of the light receiving unit. The light receiving unit 42a includes a light guide 422 extending in the transport direction and a photodetector 423 attached to one end of the light guide 422. The photodetector 423 is, for example, a photodiode, an avalanche photodiode, a photomultiplier tube, or the like. The light guide 422 is made of a transparent material, and has a rough surface on which the laser light L1 is irregularly reflected on the inner surface 422a opposite to the incident side of the laser light L1 from the light projecting unit 41.
The laser beam L1 from the light projecting unit 41 is irregularly reflected by the inner surface 422a, and is repeatedly reflected by the inner surface of the light guide 422, and a part thereof is detected by the photodetector 423. Even with such a light receiving part 42a, an effect equivalent to that of the light receiving part 42 described above can be obtained.
In addition, according to the light receiving unit 42a, the length of the light guide 422 in the transport direction can be easily changed, so that the light receiving range in the transport direction in which the light receiving unit 42a can receive light can be easily lengthened.
And while extending the light-receiving range of the conveyance direction which the light-receiving part 42a can receive, and lengthening the range of the conveyance direction in which the light projection part 41 carries out parallel scanning of the laser beam L1, the detection range of the front end of the shape steel K is made into a conveyance direction. Can be long. And if the detection range of the front end of the shape steel K is lengthened in the conveyance direction, the interval between the passage detection sets 33 can be lengthened, so the number of passage detection sets 33 can be reduced and the cost can be reduced. .

In the present embodiment, the passage detection unit 3 detects the passage of the rear end of the die steel K, and the position detection unit 4 detects the position of the front end of the die steel K at that time. The position detection unit 4 is provided on the upstream side in the conveyance direction, the passage detection unit 3 detects the passage of the front end that is the downstream end of the steel mold K, and the rear end that is the upstream end of the steel mold K at that time The position detector 4 may detect the position.
In the present embodiment, a plurality of passage detection sets 33 are provided, but a single set may be used.
Further, in the passage detection unit 3, the passage of the steel plate K is detected such that the light from the passage light projecting unit 31 is directly received by the passage light receiving unit 32, but the light from the passage light projecting unit 31 is transmitted to the steel plate K. The passage of the steel plate K may be detected by reflecting the reflected light and allowing the passage light receiving unit 32 to receive the reflected light.

(Second Embodiment)
Next, a length measuring apparatus according to the second embodiment will be described.
The length measurement device according to the present embodiment is different from the length measurement device according to the first embodiment in the configuration of the position detection unit 4, and the configuration that is not related to the position detection unit 4 is the same.
FIG. 8 is a configuration diagram of the length measuring device 1a. The same number is attached | subjected to the same structure as the length measuring apparatus which concerns on 1st Embodiment, and description is abbreviate | omitted.
The position detection unit 7 includes a light projecting unit 71 that projects light toward the transport line 2 and an imaging unit 72 with a telecentric lens 73 that faces the light projecting unit 71 and the transport line 2 in the horizontal direction. . The imaging unit 72 is a CCD camera, for example. A plurality of imaging units 72 are juxtaposed in the transport direction. The imaging unit 72 is provided so that the optical axis of the telecentric lens 73 is substantially orthogonal to the transport direction. A detection range is provided inside a range in the transport direction in which the imaging unit 72 can capture an image. This detection range must be wider than the interval between the passage detection sets 33.
The imaging unit 72 always images the conveyance line 2 during conveyance of the steel pattern K, and even when the passage detection unit 3 detects the passage of the rear end of the mold steel K, the imaging unit 72 of the mold steel K conveyed through the conveyance line 2 is captured. The front end is imaged.
Further, the position detection unit 7 includes an image processing unit 74, and the image processing unit 74 binarizes the image captured by the imaging unit 72 with a predetermined density, and controls the binarized image to the control unit. 6 is transmitted. Based on the binarized image, the control unit 6 determines whether or not the front end of the shape steel K is within the detection range, and when the front end is present, calculates the position of the front end.
The light projecting unit 71 may be anything that emits light, such as an LED or a light bulb.
Moreover, although the number of the imaging parts 72 was made into multiple, one may be sufficient.

Next, determination of whether or not the front end of the shape steel K is within the detection range of the position detection unit 7 and a method for detecting the position of the front end when the front end is within the detection range will be described.
FIG. 9 is an image obtained by binarizing the captured image captured by the imaging unit 72. The image is displayed by connecting the captured images captured by the plurality of imaging units 72.
In FIG. 9, the front end of the shape steel K is reflected in the central portion of the image. If the shape steel K is present in the detection range, the portion becomes a dark image, so that the binarized image is displayed as a dark image.
Therefore, if a high-density image extends from the upstream side in the transport direction toward the downstream side in the binarized image, it can be determined that the front end of the steel plate K is within the detection range. The extended tip represents the position of the front end of the steel plate K. And since the position of each pixel of a picked-up image and the position of the conveyance direction in a detection range are related, the position of the front end of the steel K can be calculated from the position of the pixel of the extended front end part. FIG. 9 illustrates the case where the imaging unit 72 captures a two-dimensional image, but the same can be done in the case where the imaging unit 72 is a line sensor that captures a one-dimensional image.

Next, a method for detecting the length of the steel plate K using the length measuring device 1a will be described.
FIG. 10 shows the flow of the detection method.
First, the control unit 6 sets a variable m indicating the number of times that the passage detection unit 3 detects passage (S11).
When conveyance of the shape steel K starts and a passage signal is received from the signal transmission unit 34 (S12), the control unit 6 stores the data of the captured image of the imaging unit 72 at that time together with the variable m in a storage unit (not shown). (S13).
And it is judged whether the variable m is more than n (S14). If the variable m is not n or more, 1 is added to the variable m (S15), the process returns to S12, waits for the next passing signal, and repeats S12 to S15.
If the variable m is greater than or equal to n in S14, the calculation unit 5 is caused to calculate the length of the shape steel K, assuming that the rear end of the shape steel K has passed through the location of the passage detection set 33 provided on the most downstream side.
The calculation unit 5 searches for data in which it is detected that the front end of the shape steel K is within the detection range from the data of the captured image of the imaging unit 72 stored in the storage unit in S13. As described above, this search is determined based on whether or not a binarized image has a dark image extending from the upstream side in the transport direction toward the downstream side (S16).
And if the data in which it is detected that the front end of the shape steel K exists in the detection range are searched, the position of the front end of the shape steel K in the data is obtained. As described above, the position of the front end is obtained from the position of the extended pixel at the front end (S17).
Next, the position of the rear end of the shape steel K when the front end of the shape steel K is within the detection range is obtained as follows. The passage detection set 33 through which the rear end has passed when the position of the front end of the shape steel K is detected is obtained by the variable m stored together with the data when the front end of the shape steel K is within the detection range. For example, if the variable m is 1, it is the first passage detection set 33, and if the variable m is 2, it is the second passage detection set 33. And the predetermined | prescribed position where the calculated | required passage detection set 33 detects the passage of the rear end of the shape steel K is the position of the rear end of the shape steel K (S18).
Next, the calculating part 5 calculates the length of the shape steel K from the position of the front end and the position of the rear end of the obtained shape steel K (S19).

According to the length measuring apparatus 1a of the present embodiment, light that is substantially orthogonal to the transport direction is selected from the light projected from the light projecting unit 71 by the telecentric lens 73, and the captured image is captured by the selected light. It is formed. And since the position of the end of the long material is detected from the captured image, even if the pass line of the long material fluctuates and the position of the long material fluctuates in the direction orthogonal to the conveying direction, Even if the cross-sectional shape of the material changes variously, the position of the end of the long material detected by the position detection unit 7 does not change. Therefore, the length of the long material can be accurately measured.
In particular, in the present embodiment, the light projecting unit 71 and the imaging unit 72 are arranged in the horizontal direction so that the position of the front end of the long material can be easily detected. However, since the telecentric lens is used, Even if the path line of the material fluctuates and the distance between the light projecting unit 71 and the imaging unit 72 and the long material fluctuates, the length of the long material can be accurately measured.
In the present embodiment, the passage detection unit 3 detects the passage of the rear end of the shape steel K, and the position detection unit 7 detects the position of the front end of the shape steel K at that time. Provided on the downstream side of the direction, the position detection unit 7 is provided on the upstream side in the transport direction, and the passage detection unit 3 detects the passage of the front end, which is the downstream end of the die steel K, and is the upstream end of the die steel K at that time The position detector 7 may detect the position of the rear end.

DESCRIPTION OF SYMBOLS 1, 1a ... Length measuring device 2 ... Conveyance line 3 ... Passage detection part 4 ... Position detection part 41 ... Light projection part 42, 42a ... Light-receiving part 422 ... Light guide Rod 5 ... Calculation unit 7 ... Position detection unit 71 ... Light projection unit 72 ... Imaging unit 73 ... Telecentric lens K ... Shape steel (long material)
L1 ... Laser beam (light)

Claims (3)

A length measuring device that measures the length of a long material conveyed in a conveyance line during conveyance,
A passage detection unit that is provided on either the upstream side or the downstream side in the transport direction and detects that the end of the one side of the long material passes a predetermined position;
A position detection unit that is provided on the other side of the upstream side and the downstream side in the transport direction and detects the position of the other side end of the long material at the passage time detected by the passage detection unit;
A calculation unit that calculates the length of the long material from the position of the other end of the long material detected by the position detection unit and the predetermined position;
The position detection unit projects light substantially orthogonal to the transport direction toward the transport line, and projects a light projecting unit that scans the light in parallel with the transport direction, and sandwiches the light projecting unit and the transport line. A light receiving portion that receives light from the light projecting portion, and when the passage detection portion detects that the one end of the long material has passed the predetermined position, The length of the other end of the long material is detected from a position where light reception by the light receiving unit of the parallel scanned light is blocked by the long material and a position where the light is not blocked by the long material. Measuring device. The light receiving unit includes a light guide extending in the transport direction and a photodetector provided on one end side of the light guide,
The length measuring device according to claim 1, wherein a part of light incident on the light guide rod from the light projecting unit is guided to the photodetector. A length measuring device that measures the length of a long material conveyed in a conveyance line during conveyance,
A passage detection unit that is provided on either the upstream side or the downstream side in the transport direction and detects that the end of the one side of the long material passes a predetermined position;
A position detection unit that is provided on the other side of the upstream side and the downstream side in the transport direction and detects the position of the other side end of the long material at the passage time detected by the passage detection unit;
A calculation unit that calculates the length of the long material from the position of the other end of the long material detected by the position detection unit and the predetermined position;
The position detection unit includes a light projecting unit that projects light toward the transport line, and an imaging unit with a telecentric lens provided to face the light projecting unit across the transport line,
The imaging unit is provided such that the optical axis of the telecentric lens is substantially orthogonal to the conveyance direction, and the passage detection unit detects that the one end of the long material has passed the predetermined position. To image the other end of the long material conveyed through the conveying line,
The position detection unit detects a position of the other end of the long material from a captured image captured by the imaging unit.

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