JP6455089B2 - Metal tube length measuring device - Google Patents

Description

  The present invention relates to a length measuring device for a metal tube, and more particularly to a device for measuring the length of a hot-worked metal base tube.

  As one of the metal tubes, a seamless metal tube is known. A seamless metal pipe is manufactured as follows, for example.

  First, a billet heated in a heating furnace is pierced and rolled. Thereby, a raw tube is obtained. Rolling or the like is performed on the raw tube. Thereby, the intended seamless metal pipe is obtained.

  When producing a seamless metal tube, for example, knowing the size of the raw tube before rolling is important for stably producing the intended seamless metal tube.

  A method for measuring the length of a raw tube is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-318316. In this publication, when capturing an image of each end of a red hot object, a camera to capture an image is automatically selected from a plurality of cameras. A camera is selected based on the determination of the presence / absence of an object and the presence / absence of an edge. At that time, the threshold value is set in consideration of the temperature information of the object.

JP 7-318316 A

  An object of the present invention is to provide an apparatus capable of efficiently measuring the length of a hot worked metal tube.

  The metal tube length measuring device according to the embodiment of the present invention is a device for measuring the axial length of a hot-worked metal base tube. The apparatus includes a first camera, a second camera, one end specifying unit, an image selecting unit, the other end specifying unit, and a length calculating unit. The first camera images one end of the metal pipe in the radial direction. The metal pipe is conveyed in the radial direction to a predetermined measurement position. The second camera is disposed on the other end side in the axial direction than the first camera. The second camera images the metal pipe in the radial direction from a plurality of imaging positions. The one end specifying unit specifies the position of one end based on an image including one end taken by the first camera. The image selection unit selects an image including the other end from the images of the metal tube taken by the second camera. The other end specifying unit specifies the position of the other end based on the image selected by the image selecting unit. The length calculation unit calculates the axial length of the metal base tube based on the position of one end specified by the one end specifying unit and the position of the other end specified by the other end specifying unit.

  The metal tube length measuring device according to the embodiment of the present invention can efficiently measure the length of a hot-worked metal tube.

It is a schematic diagram which shows schematic structure of the length measuring apparatus of the metal tube by embodiment of this invention. It is a schematic diagram which shows schematic structure of the camera with which the length measuring apparatus of a metal tube shown in FIG. It is a flowchart which shows the one end specific process which an image control apparatus performs. It is explanatory drawing which shows the positional relationship of the lens and CCD element which a camera main body has, and a metal elementary tube. It is explanatory drawing which shows an example of the image containing the one end image | photographed with the camera. It is a flowchart which shows the other end specific process which an image control apparatus performs. It is explanatory drawing which shows an example of the image containing the other end image | photographed with the camera. It is a flowchart which shows the length measurement process which an image control apparatus performs. It is a schematic diagram which shows schematic structure of the application example of the length measuring apparatus of the metal pipe by embodiment of this invention. It is a schematic diagram which shows schematic structure of the other application example of the length measuring apparatus of the metal pipe by embodiment of this invention.

  The metal tube length measuring device according to the embodiment of the present invention is a device for measuring the length of a hot-worked metal base tube. The apparatus includes a first camera, a second camera, one end specifying unit, an image selecting unit, the other end specifying unit, and a length calculating unit. The first camera images one end of the metal pipe in the radial direction. The metal pipe is conveyed in the radial direction to a predetermined measurement position. The second camera is disposed on the other end side in the axial direction than the first camera. The second camera images the metal pipe in the radial direction from a plurality of imaging positions. The one end specifying unit specifies the position of one end based on an image including one end taken by the first camera. The image selection unit selects an image including the other end from the images of the metal tube taken by the second camera. The other end specifying unit specifies the position of the other end based on the image selected by the image selecting unit. The length calculation unit calculates the length of the metal base tube based on the position of one end specified by the one end specifying unit and the position of the other end specified by the other end specifying unit.

  When the metal element tube is conveyed in the axial direction, the metal element tube may slip when the conveyance of the metal element tube is stopped. In this case, the metal pipe does not stop at a predetermined position. Therefore, when there is only one camera for photographing one end, there is a possibility that one end cannot be photographed by the camera. Therefore, when photographing one end of the metal base tube conveyed in the axial direction, it is necessary to install a plurality of cameras. Alternatively, it is necessary to provide one camera so as to be movable in the axial direction of the metal tube.

  On the other hand, in the said apparatus, the one end of the metal base tube conveyed by radial direction is image | photographed with a 1st camera. Therefore, the time required for specifying the position of one end can be shortened compared with the case where there are a plurality of cameras that capture one end and the case where the camera that captures one end can move in the axial direction of the metal tube.

  In the above apparatus, the second camera images the metal tube from a plurality of imaging positions. Therefore, the position of the other end can be specified even when the lengths of the metal pipes to be measured are different.

  In addition, the metal tube taken by the second camera is conveyed in the radial direction. Therefore, compared to the case where the sheet is conveyed in the axial direction, the sliding in the axial direction when the conveyance is stopped does not occur. As a result, if the approximate length of the metal tube is known in advance, it can be predicted from which shooting position the other end is included in the image taken from. Therefore, the time required to search for an image including the other end can be shortened.

  Here, the hot-worked metal tube is a metal tube at a stage prior to the seamless metal tube as a product. More specifically, it refers to a metal tube that is heated to emit infrared light.

  In the above apparatus, the second camera may include a plurality of fixed cameras. Here, the plurality of fixed cameras are arranged at different positions in the axial direction of the metal base tube. Alternatively, the second camera may be movable in the axial direction of the metal tube.

  The device preferably further comprises a rotating device. The rotating device rotates the metal pipe in the circumferential direction at the measurement position.

  The shape of one end and the other end may differ in the circumferential direction. Therefore, accurately grasping the shapes of the one end and the other end is important for improving the measurement accuracy of the length of the metal tube.

  In the above aspect, one end and the other end of the metal base tube can be photographed at different positions in the circumferential direction. Therefore, the shape of one end and the other end can be specified. As a result, the accuracy of measuring the length of the metal tube can be improved.

  Preferably, the device further includes a first adjustment unit and a second adjustment unit. A 1st adjustment part adjusts the exposure time of a 1st camera, and makes the luminance value of the metal tube | pipe image | photographed with the 1st camera a predetermined magnitude | size. A 2nd adjustment part adjusts the exposure time of a 2nd camera, and makes the luminance value of the metal tube | pipe image | photographed with the 2nd camera a predetermined magnitude | size. The first camera photographs one end with the exposure time adjusted by the first adjustment unit. The second camera photographs the other end with the exposure time adjusted by the second adjustment unit.

  In the said aspect, the optimal image for the measurement of the length of a metal elementary tube can be obtained. Therefore, it is possible to improve the accuracy of measuring the length of the metal pipe.

  Preferably, the device further includes a first calculation unit and a second calculation unit. The first calculation unit calculates the length per pixel of the image captured by the first camera based on the image of one end captured by the first camera. The second calculation unit calculates the length per pixel of the image captured by the second camera based on the image of the other end captured by the second camera. The one end specifying unit specifies the position of one end based on the length per pixel calculated by the first calculation unit. The other end specifying unit specifies the position of the other end based on the length per pixel calculated by the second calculation unit.

  In the said aspect, the precision of the length measurement of a metal elementary tube can further be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

  FIG. 1 is a schematic diagram showing a schematic configuration of a metal tube length measuring device 10 (hereinafter simply referred to as device 10) according to an embodiment of the present invention. The apparatus 10 includes a plurality of cameras 12, a rotation device 14, an image processing device 16, and a rotation / lift control device 18.

  As shown in FIG. 2, each of the plurality of cameras 12 includes a camera body 12A, a filter 12B, and a case 12C. The camera body 12A is, for example, a camera that can capture a plurality of still images per second. The camera body 12A includes a lens and a CCD element. The filter 12B is disposed at a position that covers the lens of the camera body 12A. The filter 12B transmits infrared light and absorbs visible light. Case 12C houses camera body 12A. The case 12C protects the camera body 12A from dust and water. A glass window 12D is provided on the front surface of the case 12C. In order to prevent dust from adhering to the glass window 12D, for example, air is periodically sprayed onto the glass window 12D. Case 12C is water cooled.

  The plurality of cameras 12 includes cameras 121 to 126.

  The camera 121 is disposed near one axial end (hereinafter simply referred to as one end) of the metal base tube 20. The position of the camera 121 in the axial direction of the metal base tube 20 is fixed. That is, the camera 121 is immovable in the axial direction of the metal tube 20. The camera 121 images one end of the metal base tube 20 from the radial direction.

  The cameras 122 to 125 are disposed on the other end side in the axial direction of the metal base tube 20 than the camera 121. The cameras 122 to 125 are arranged in a line in the axial direction of the metal tube 20. The camera 122 is disposed closest to the camera 121. The camera 123 is arranged next to the camera 122. The camera 124 is disposed next to the camera 123. The camera 125 is disposed next to the camera 124. The positions of the cameras 122 to 125 in the axial direction of the metal base tube 20 are fixed. That is, the cameras 122 to 125 are not movable in the axial direction of the metal tube 20. The cameras 122 to 125 photograph the metal base tube 20 from the radial direction. Any of the cameras 122 to 125 captures the other end of the metal base tube 20 in the axial direction (hereinafter simply referred to as the other end). Among the cameras 122 to 125, the shooting areas (fields of view) of two adjacent cameras overlap. Thereby, any one of the cameras 122 to 125 can photograph the other end of the metal base tube 20. The distance of the cameras 122 to 125 from the camera 121 is set in advance. Specifically, for example, the distance from the center of the image captured by the camera 121 to the center of the image captured by the cameras 122 to 125 is set in advance.

  The camera 126 is disposed on the other end side in the axial direction of the metal base tube 20 than the camera 121. The camera 126 is arranged at a position different from the cameras 122 to 125. The position of the camera 126 in the axial direction of the metal base tube 20 is fixed. That is, the camera 126 cannot move in the axial direction of the metal tube 20. The camera 126 images the metal base tube 20 from the radial direction. The image captured by the camera 126 is used to specify which of the cameras 122 to 125 is capturing the other end of the metal tube 20.

  Here, the metal base tube 20 is, for example, a metal tube obtained by piercing and rolling a heated billet, and is a metal tube at a stage prior to a seamless metal tube as a product. That is, the metal base tube 20 is a hot-worked metal tube. In other words, the metal tube 20 is a metal tube that emits infrared light.

  The metal base tube 20 is transported in the radial direction by a plurality of transport devices 22. The plurality of transfer devices 22 are arranged side by side in the axial direction of the metal base tube 20. The transport device 22 is, for example, a transport band. The plurality of transfer devices 22 are arranged side by side in the axial direction of the metal base tube 20. The plurality of transfer devices 22 are controlled by a transfer control device 24. As a means for conveying the metal base tube 20 in the radial direction, there are, for example, a walking beam or a kicker that gives a speed in the radial direction in addition to the conveyance band.

  The metal base tube 20 is rotated in the circumferential direction by the plurality of rotating devices 14. The plurality of rotating devices 14 are controlled by a rotation / lift control device 18. The plurality of rotating devices 14 are arranged side by side in the axial direction of the metal base tube 20. The rotating device 14 includes, for example, a pair of rollers 14A and 14A. The roller 14A is rotated by a driving source such as a motor, for example. The rotating device 14 further includes a lifting device. The lifting device lifts and lowers the pair of rollers 14A and 14A. That is, the metal base tube 20 moves up and down by the rotating device 14. When the pair of rollers 14 </ b> A and 14 </ b> A is positioned at the lower end, the metal base tube 20 is supported by the transport device 12. That is, the pair of rollers 14 </ b> A and 14 </ b> A is located away from the metal base tube 20. On the other hand, when the pair of rollers 14A and 14A is positioned at the upper end, the metal base tube 20 is supported by the pair of rollers 14A and 14A. At this time, the metal base tube 20 rotates in the circumferential direction by the rotation of the pair of rollers 14A and 14A.

  The image control device 16 controls photographing of the metal base tube 20 by the plurality of cameras 12. Data sent from the rotation / elevation control device 18, the conveyance control device 24 and the host computer 26 is input to the image control device 16. Here, the host computer 26 monitors the entire manufacturing process of the metal blank 20. The data sent from the host computer 26 is, for example, data relating to the metal base tube 20. The data regarding the metal base tube 20 is, for example, the diameter and the axial length of the metal base tube 20, the temperature of the metal base tube 20, and the like. The data sent from the rotation / elevation control device 18 is data indicating that the metal tube 20 has been raised to a predetermined rotation position, for example. The data sent from the conveyance control device 24 is data indicating that the metal base tube 20 has been conveyed to a predetermined position (position where photographing by a plurality of cameras 12 is performed), for example.

  The image control device 16 stores a table 16A. The table 16A shows the correspondence between the temperature of the metal tube 20 and the initial value of the exposure time when the camera 12 captures the metal tube 20. The image control device 16 refers to the table 16A to obtain an exposure time corresponding to the temperature of the metal base tube 20 sent from the host process computer 26. The image control device 16 captures the metal base tube 20 with the camera 12 based on the acquired exposure time.

  Subsequently, a control process executed by the image control device 16 will be described with reference to FIGS.

  First, the one end specifying process executed by the image control device 16 will be described with reference to FIG. The image control device 16 executes one-end identification processing when the metal base tube 20 is transported to a predetermined position by the transport device 22 and the metal base tube 20 is rotated in the circumferential direction by the rotating device 14. To do.

  First, in step S11, the image control device 16 determines whether or not it is the first shooting. In the case of the first shooting (step S11: YES), the image control device 16 reads from the table 16A the exposure time corresponding to the temperature of the metal base tube 20 sent from the host computer 26 in step S12. . Subsequently, in step S <b> 13, the image control device 16 photographs one end of the metal base tube 20 based on the exposure time read from the table 16 </ b> A.

  Subsequently, in step S14, the image control device 16 determines whether or not the luminance value of one end of the metal shell 20 in the captured image is equal to or higher than the target value. Specifically, it is as follows. First, the image control device 16 extracts pixels having a luminance value equal to or higher than a predetermined threshold value in a captured image. An average value of the luminance values of the extracted pixels is calculated. The calculated average value is compared with the target value.

  If the calculated average value is equal to or greater than the target value (step S14: YES), the image control device 16 calculates the length per pixel based on the captured image in step S15. The details will be described below.

  FIG. 4 is an explanatory diagram showing the positional relationship between the lens 13A and the CCD element 13B included in the camera body 12A and the metal base tube 20. In FIG. 4, f indicates a focal length. Referring to FIG. 4, the optical axis L1 of the camera body 12A passes through the center C1 of the calibration jig 28, the center C2 of the lens 13A, and the center C3 of the CCD element 13B. When the diameter R of the metal base tube 20 is different from the diameter r of the calibration jig 28, the visual field length (length in the vertical direction of the visual field) T1 of the camera 121 when photographing the metal base pipe 20 is The field of view length of the camera 121 when taking a picture (length in the vertical direction of the field of view) T0 is shorter. For this reason, the length per pixel of the image captured by the camera 121 differs between when the metal base tube 20 is photographed and when the calibration jig 28 is photographed.

  A circle (hereinafter, referred to as a circle 20 </ b> A) indicating the metal pipe 20 shown in FIG. 4 is represented by the following formula (1).

  Here, x and y indicate coordinates when the center C1 of the calibration jig 28 is used as a reference.

  In FIG. 4, a straight line A1 that intersects with the circle 20A is represented by the following equation (2).

Here, L is the distance in the horizontal direction from the center C2 to the center C1. H is a distance (camera installation height) from the lower end of the calibration jig 28 to the center C2. θ ₀ is the optical axis angle (camera mounting angle). That is, θ ₀ is an angle formed by a straight line A2 that passes through the center C2 and extends in the vertical direction, and the optical axis L1. θ ₀ is expressed by the following equation (3). θ ₁ is an angle formed by the optical axis L1 and the straight line A1.

  From the equations (1) and (2), the intersection point X between the circle 20A and the straight line A1 is calculated. Subsequently, a straight line A3 passing through the intersection point X and perpendicular to the optical axis L1 is calculated. Subsequently, an intersection CP of a straight line (line connecting the center C2 and the lower end of the CCD element 13B) A4 and the straight line A3 that defines the upper end of the field of view is calculated. Subsequently, the length of the perpendicular drawn from the intersection CP to the optical axis L1 is calculated. The length of the perpendicular corresponds to half the length ((T1) / 2) of the captured image in the vertical direction. That is, the length per pixel is calculated by dividing the length of the perpendicular by half the number of pixels in the vertical direction of the photographed image.

  Subsequently, in S16, the image control device 16 specifies the position of one end of the metal base tube 20 included in the captured image. Specifically, first, one end of the metal base tube 20 is calculated. Here, as shown in FIG. 5, the one end 1 </ b> E is a point located on the other end side in the axial direction among the edges on the one end side in the axial direction of the photographed metal base tube 20. Subsequently, the image control device 16 calculates a distance D1 between the one end 1E and the reference position RP1. The distance D1 is a distance in the axial direction of the metal base tube 20. The reference position RP1 is, for example, the center of the image captured by the camera 121. The distance D1 is calculated by multiplying the number of pixels from the one end 1E to the reference position RP1 by the length per pixel calculated in S15. Thereafter, the image control device 16 ends the identification process.

  If the calculated average value is not equal to or greater than the target value (step S14: NO), the image control device 16 adjusts the exposure time in S17. The adjustment of the exposure time is performed by PID control, for example. When the adjustment of the exposure time is completed, one end of the metal base tube 20 is photographed with the adjusted exposure time (step S13). Subsequent processing executed by the image control device 16 is as already described.

  The other end specifying process executed by the image control device 16 will be described with reference to FIG. The image control device 16 performs the other end identification process when the metal base tube 20 is transported to a predetermined position by the transport device 22 and the metal base tube 20 is rotated in the circumferential direction by the rotating device 14. Run. The other end specifying process may be performed in parallel with the one end specifying process, or may be performed after the one end specifying process is completed.

  First, in step S <b> 21, the image control device 16 selects the camera 12 that can photograph the other end of the metal base tube 20 among the cameras 122 to 125. Specifically, the camera 126 photographs the other end of the metal tube 20. Here, the cameras 122 to 125 and the camera 126 have a predetermined positional relationship. Therefore, the positional relationship between the other end of the metal shell 20 and the cameras 122 to 125 can be acquired based on the image captured by the camera 126. Based on the acquired positional relationship, the camera 12 that can photograph the other end of the metal tube 20 is selected. As the exposure time of the camera 126, for example, an exposure time corresponding to the average value of the exposure times stored in the table 16A is set. When the brightness is insufficient or halation occurs, the exposure time is adjusted as in the case of the camera 121.

  Subsequently, in step 22, the image control device 16 determines whether or not it is the first shooting. In the case of the first shooting (step S22: YES), the image control device 16 reads from the table 16A the exposure time corresponding to the temperature of the metal base tube 20 sent from the host computer 26 in step S23. . Subsequently, in step S24, the image control device 16 photographs the other end of the metal tube 20 based on the exposure time read from the table 16A.

  Subsequently, in step S25, the image control device 16 determines whether or not the luminance value of the other end of the metal shell 20 in the captured image is equal to or higher than a target value. Specifically, it is as follows. First, the image control device 16 extracts pixels having a luminance value equal to or higher than a predetermined threshold value in a captured image. An average value of the luminance values of the extracted pixels is calculated. The calculated average value is compared with the target value.

  When the calculated average value is equal to or greater than the target value (step S25: YES), the image control device 16 confirms in step 26 that the other end of the metal tube 20 is included in the captured image. As a method for confirming whether or not the other end is included, for example, whether there is a boundary where the brightness value changes rapidly in the left-right direction of the captured image, and whether the boundary extends in the vertical direction of the captured image. There is a method of confirming based on whether or not. In addition, when the other end is not included in the photographed image, for example, (1) Step S21 may be performed again, or (2) whether the other end is included in the image photographed by another camera. It is also possible to select the image including the other end. The above (2) can be realized, for example, by performing a series of processes after the process of step S21 is completed for all the cameras 122 to 125. Subsequently, in step S27, the image control device 16 calculates the length per pixel based on the captured image. Note that the method for calculating the length per pixel is the same as the method already described (the method adopted in the one-point specifying process), and thus detailed description thereof is omitted.

  Subsequently, in step S28, the image control device 16 specifies the position of the other end of the metal shell 20 included in the photographed image. Specifically, first, the image control device 16 calculates the other end of the metal base tube 20. Here, as shown in FIG. 7, the other end 2 </ b> E is a point that is located closest to one end in the axial direction at the edge on the other end side in the axial direction of the photographed metal base tube 20. Subsequently, the image control device 16 calculates a distance D2 between the other end 2E and the reference position RP2. The distance D <b> 2 is a distance in the axial direction of the metal base tube 20. The reference position RP2 is, for example, the center of the image captured by the selected camera 12 selected in S21. The distance D2 is calculated by multiplying the number of pixels from the other end 2E to the reference position RP2 by the length per pixel calculated in S26. Thereafter, the image control device 16 ends the other end identification process.

  If the calculated average value is not equal to or greater than the target value (step S25: NO), the image control device 16 adjusts the exposure time in step S29. The adjustment of the exposure time is performed by PID control, for example. When the adjustment of the exposure time is completed, the other end of the metal tube 20 is photographed with the adjusted exposure time (step S24). Subsequent processing executed by the image control device 16 is as already described.

  The length measurement process executed by the image control device 16 will be described with reference to FIG. First, in step S31, the image control device 16 determines whether the one end specifying process and the other end ending process are completed. If not finished (step S31: NO), the image control device 16 waits until the process is finished. If it has been completed (step S31: YES), the image control device 16 calculates the length of the metal blank 20 in step S32. Specifically, the distance between the camera 12 (camera 121) that captured the image used to specify the position of one end and the camera 12 (any of cameras 122 to 125) that captured the image used to specify the position of the other end. That is, the distance between the reference position RP1 and the reference position RP2, the distance D1, and the distance D2 are added. Thereafter, the image control device 16 ends the length measurement process.

  In the apparatus 10, one end of the metal base tube 20 that has been conveyed in the radial direction is photographed by the camera 121. Therefore, the time required to specify the position of one end can be shortened compared to the case where there are a plurality of cameras that capture one end and the case where the camera that captures one end can move in the axial direction of the metal tube 20.

  In the apparatus 10, the other end of the metal base tube 20 is photographed by one camera 12 selected from the four cameras 122 to 125. Therefore, the position of the other end can be specified even when the length of the metal base tube 20 to be measured is different.

  In the apparatus 10, the photographing of the metal elementary tube 20 is repeated until the photographed metal elementary tube 20 has a predetermined luminance value. Therefore, the accuracy of specifying the positions of one end and the other end of the metal base tube 20 is improved.

  In the apparatus 10, the positions of one end and the other end of the metal tube 20 are specified using the length per pixel calculated every time an image is taken. Therefore, the accuracy of specifying the positions of one end and the other end of the metal base tube 20 is improved.

  In the apparatus 10, photographing is performed while rotating the metal pipe 20 in the circumferential direction. Therefore, for example, even if there is a shape defect at one end and the other end of the metal base tube 20, the positions of the one end and the other end can be specified with high accuracy.

[Application example 1 of the device]
With reference to FIG. 9, apparatus 10A according to application example 1 of the embodiment of the present invention will be described. The device 10 </ b> A does not include the camera 126 compared to the device 10. In this case, the number of cameras 12 required for specifying the position of the other end of the metal base tube 20 can be reduced.

  In the apparatus 10A, for example, the camera 12 that captures the other end of the metal base tube 20 is specified as follows. First, the metal elementary tube 20 is photographed by the four cameras 122 to 125. Subsequently, an image including the other end of the metal base tube 20 is selected from the captured images of the metal base tube 20. Subsequently, the camera that captured the selected image is selected. As the exposure time of the cameras 122 to 125, for example, an exposure time corresponding to the average value of the exposure times stored in the table 16A is set. When luminance shortage or halation occurs, the exposure time is adjusted as described in the above embodiment.

[Application example 2 of the device]
With reference to FIG. 10, apparatus 10B according to application example 2 of the embodiment of the present invention will be described. Compared with the apparatus 10, the apparatus 10 </ b> B includes only a camera 122 as the camera 12 that photographs the other end of the metal base tube 20. The camera 122 is arranged to be movable in the axial direction of the metal base tube 20. In this case, the number of cameras 12 required for specifying the position of the other end of the metal base tube 20 can be reduced.

  In the apparatus 10B, for example, the metal elementary tube 20 is photographed while moving the camera 122, and the position where the other end of the metal elementary tube 20 can be photographed is specified.

  As mentioned above, although embodiment of this invention has been explained in full detail, these are illustrations to the last and this invention is not limited at all by the above-mentioned embodiment.

  For example, the length per pixel may not be calculated every time an image is taken.

  For example, in the device 10A and the device 10B, the image control device 16 receives data related to the approximate length of the metal tube 20 from the host computer 26, and shoots the other end of the metal tube 20 based on the data. 12 may be specified.

  For example, photographing during exposure time control may be performed by all cameras regardless of the presence or absence of a tube end in the image. In this case, control of the camera that captures the tube end converges, but if the same control is performed on a camera that does not capture the tube end, the exposure time diverges. Therefore, when a certain number of pixels having a certain luminance or higher cannot be found, the control is not further performed and the next shooting is started. As a result, the exposure time is controlled only by the camera that photographs the tube end.

10: Device, 121: Camera, 122: Camera, 123: Camera, 124: Camera, 125: Camera, 14: Rotating device, 16: Image control device, 20: Metal base tube

Claims (5)

An apparatus for measuring the length of a hot-worked metal tube,
A single first camera in which a position of the metal pipe in the axial direction is fixed and an axial end of the metal pipe is photographed in the radial direction;
Means for conveying the metal pipe in the radial direction to a predetermined measurement position at which one end of the metal pipe in the axial direction is photographed by the first camera;
A second camera that is disposed on the other end side in the axial direction from the first camera, and shoots the metal element tube in a radial direction from a plurality of imaging positions in the axial direction of the metal element tube;
One end specifying unit for specifying the position of the one end based on an image including the one end captured by the first camera;
Based on the image of the metal tube taken by the second camera, the other end specifying unit that specifies the position of the other end;
Based on the position of the one end specified by the one end specifying unit and the position of the other end specified by the other end specifying unit, a length calculating unit that calculates the length of the metal base tube ,
The second camera includes a plurality of fixed cameras arranged at different positions in the axial direction,
A third camera used to identify which of the plurality of fixed cameras is photographing the other end of the metal tube;
The other end specifying unit acquires a positional relationship between the other end of the metal base tube and the plurality of fixed cameras based on an image taken by the third camera, and the metal based on the acquired positional relationship. A metal element tube that selects the fixed camera capable of photographing the other end of the element tube and identifies the position of the other end based on an image including the other end of the metal element tube photographed by the selected fixed camera. Length measuring device. The length measuring apparatus for a metal pipe according to claim 1, further comprising:
An apparatus for measuring a length of a metal pipe, comprising: a rotating device that rotates the metal pipe in a circumferential direction of the metal pipe at the measurement position. The length measuring apparatus for a metal pipe according to claim 1 or 2, further comprising:
A first adjustment unit that adjusts an exposure time of the first camera and sets a luminance value of the metal tube taken by the first camera to a predetermined magnitude;
A second adjustment unit that adjusts an exposure time of the second camera and sets a luminance value of the metal shell taken by the second camera to a predetermined magnitude;
The first camera photographs the one end with the exposure time adjusted by the first adjustment unit,
The apparatus for measuring a length of a metal tube, wherein the second camera photographs the other end with an exposure time adjusted by the second adjustment unit. It is the length measuring apparatus of the metal pipe according to claim 3,
The first adjustment unit and the second adjustment unit are devices for measuring the length of a metal tube, referring to a table, for obtaining an exposure time corresponding to the temperature of the metal tube sent from the host computer. The length measuring apparatus for a metal pipe according to any one of claims 1 to 4, further comprising:
A first calculation unit that calculates a length per pixel of an image captured by the first camera each time an image is captured based on the image of the one end captured by the first camera;
A second calculator that calculates the length per pixel of the image captured by the second camera each time an image is captured based on the image of the other end captured by the second camera;
The one end specifying unit specifies the position of the one end based on the length per pixel calculated by the first calculation unit,
The said other end specific | specification part is a length measuring apparatus of the metal elementary tube which specifies the position of the said other end based on the length per pixel which the said 2nd calculation part calculated.

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