Conveyor speed measuring device and conveyor speed measuring method

Abstract

The present invention provides a conveying speed measuring device that improves the accuracy of conveying speed measurement by accommodating vibrations that include two directions perpendicular to the conveying direction of the conveyed material. [Solution] A transport speed measuring device used in a transport system for transporting a material that has a circular outer shape when viewed in the transport direction and extends with the transport direction as its longitudinal direction, comprising: a center coordinate measuring unit for measuring the center coordinates of the material to be transported; a laser Doppler velocometer; a mirror that reflects a laser emitted from the laser Doppler velocometer and guides it to the material to be transported; a rotational drive mechanism for rotating the mirror; and a first control unit that controls the rotational drive mechanism so that the laser follows the center coordinates.

Description

Technical Field

[0001] The present invention relates to a conveyance speed measurement device and a conveyance speed measurement method.

Background Art

[0002] Generally, when performing heat treatment or polishing such as full circumferential polishing on a cylindrical material such as a metal pipe, a skew conveyance method is adopted in which the cylindrical material is linearly conveyed while being rotated. In this skew conveyance method, since the material is conveyed as skew rolls with many turning rollers angled, it is difficult to control the linear conveyance speed of the cylindrical material at a constant speed due to variations in the angles, roll diameters, roll widths, etc. of the respective turning rollers.

[0003] Taking the case of heat-treating a cylindrical material with an induction heating device as an example, the heat input temperature for heat-treating the cylindrical material is proportional to the time the cylindrical material stays in the IH (Induction Heating) coil. Therefore, if the cylindrical material cannot be conveyed at a constant speed, unevenness in heat input occurs in the circumferential and longitudinal directions, leading to a deterioration in heat treatment quality. Similarly, when polishing the cylindrical material, since the time the cylindrical material contacts the polishing buff is proportional to the polishing amount, variations in the conveyance speed directly result in polishing unevenness.

[0004] In order to solve such problems, Patent Document 1 discloses a conveyance speed control device for a circular long material during conveyance by the following skew rolls. The conveyance speed control device includes a touch roller, a rotational peripheral speed detector, a horizontal rotation device, a rotation angle detector, and an arithmetic device.

[0005] The touch roller rotates while contacting the outer surface of the circular long material. The rotational peripheral speed detector is connected to the rotation axis of the touch roller and measures its rotational peripheral speed. The horizontal rotation device supports the touch roller and the rotational peripheral speed detector so as to be rotatable in the horizontal direction from below. The rotation angle detector detects the rotation angle of the horizontal rotation device. The arithmetic device calculates the conveyance speed in the longitudinal direction of the circular long material from the detected rotational peripheral speed value and the detected rotation angle value.

[0006] Furthermore, Patent Document 2 discloses the following length measuring device for electric resistance welded (ERW) steel pipes. This length measuring device measures the transport speed of the ERW steel pipe using a laser Doppler velocometer. The laser Doppler velocometer is mounted on the side of the ERW steel pipe so that its distance from the pipe can be changed. This length measuring device includes a position control device that controls the position of the laser Doppler velocometer so that its distance from the ERW steel pipe remains constant. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 4-164711 [Patent Document 2] Japanese Patent Publication No. 2019-15609 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, the conveying speed measurement method described in Patent Document 1 above detects the circumferential speed of the long circular material using a touch roller, but there are issues with speed measurement errors due to the slippage of the touch roller, and wear management of the touch roller is necessary.

[0009] Therefore, Patent Document 2 proposes a length measurement method using a laser Doppler velocometer, which is a non-contact speed sensor, in order to solve the problems of Patent Document 1. However, Patent Document 2 assumes that the steel pipe is transported using a V-roller (a roller with a V-shaped recess when viewed in the transport direction), and the position control of the Doppler velocometer can respond to the lateral sway of the steel pipe (sway in the axial direction of the roller), but it is difficult to respond to vertical and lateral sway, including the vertical direction which is perpendicular to the transport direction and the lateral direction. In particular, when skew transporting, vertical and lateral sway (eccentricity of the cylindrical material) occurs, so it is important to respond to such sway of the cylindrical material.

[0010] In view of the above issues, the present invention aims to provide a conveying speed measuring device and a conveying speed measuring method that improve the accuracy of conveying speed measurement by responding to vibrations including two directions perpendicular to the conveying direction of the conveyed material. [Means for solving the problem]

[0011] A conveying speed measuring device according to one aspect of the present invention is a conveying speed measuring device used in a conveying system that conveys a material to be conveyed, which has a circular outer shape when viewed in the conveying direction and extends with the conveying direction as its longitudinal direction, A center coordinate measuring unit for measuring the center coordinates of the material to be conveyed, A laser Doppler velocometer and A mirror that reflects the laser emitted from the laser Doppler velocometer and guides it to the material to be transported, A rotational drive mechanism for rotating the aforementioned mirror, The system comprises a first control unit that controls the rotational drive mechanism so that the laser follows the central coordinates (first configuration).

[0012] Furthermore, in the first configuration described above, the center coordinate measuring unit is An outer diameter sensor comprising a first light emitter and a first light receiver arranged opposite to each other in a first direction perpendicular to the transport direction, and a second light emitter and a second light receiver arranged opposite to each other in a second direction perpendicular to the transport direction and the first direction, wherein the transported material is configured to pass through its interior, A center coordinate calculation unit calculates the center coordinates based on the light signals output from the first and second light receivers, respectively. A configuration having the following is also possible (second configuration).

[0013] Furthermore, in the first or second configuration described above, the first control unit is A mirror angle calculation unit calculates the angle of the mirror such that the center coordinates are located on the extension of the optical path of the laser reflected by the mirror, A mirror angle control unit controls the rotation drive mechanism to control the angle of the mirror to a target value which is the calculated angle of the mirror, A configuration having the following is also possible (third configuration).

[0014] Furthermore, in the third configuration described above, a linear drive mechanism is provided to linearly drive the laser Doppler velocometer so that the distance between it and the mirror is variable, A second control unit controls the linear drive mechanism so that the optical path length between the laser Doppler velocometer and the transported material becomes a predetermined target value, based on a first distance between the center coordinates and the rotation axis of the mirror obtained in the process of calculating the angle of the mirror by the mirror angle calculation unit. A configuration including the following is also possible (fourth configuration).

[0015] Furthermore, in the fourth configuration described above, the second control unit is A linear target position determination unit determines the linear target position of the laser Doppler velocometer such that the optical path length becomes the predetermined target value based on the first distance, A linear control unit controls the linear drive mechanism to control the position of the laser Doppler velocometer to the determined linear target position, A configuration having the following is also possible (fifth configuration).

[0016] Furthermore, in the fourth or fifth configuration described above, the second control unit may be configured to control the optical path length to be the predetermined target value ± depth of field (sixth configuration).

[0017] Furthermore, in any of the above configurations 1 to 6, the transport system may be configured to transport the material to be transported in a skew manner (configuration 7).

[0018] Furthermore, a method for measuring the conveying speed according to one aspect of the present invention is a method for measuring the conveying speed used in a conveying system that conveys a material to be conveyed, which has a circular outer shape when viewed in the conveying direction and extends with the conveying direction as its longitudinal direction, A first step is to measure the central coordinates of the material to be conveyed, A second step of calculating an angle of the mirror such that the center coordinates are located on an extension of an optical path along which laser emitted from the laser Doppler velocimeter is reflected by the mirror and guided to the conveyed material; A third step of controlling a rotation drive mechanism that rotationally drives the mirror so as to control the angle of the mirror to a target value that is the calculated angle of the mirror (eighth configuration).

Advantages of the Invention

[0019] According to the present invention, by corresponding to vibrations including two directions orthogonal to the conveyance direction of the conveyed material, it is possible to improve the measurement accuracy of the conveyance speed.

Brief Description of the Drawings

[0020] [Figure 1] FIG. 1 is a diagram showing a configuration example of a conveyance system. [Figure 2] FIG. 2 is a diagram showing a configuration example of a conveyance speed measurement device. [Figure 3] FIG. 3 is a diagram showing a configuration example of an outer diameter sensor. [Figure 4] FIG. 4 is a diagram showing an internal configuration example of a controller. [Figure 5] FIG. 5 is a diagram for explaining a method of calculating a mirror angle. [Figure 6] FIG. 6 is a diagram showing a configuration example of a mirror angle control unit. [Figure 7] FIG. 7 is a diagram showing a configuration example of a linear control unit.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.

[0022] <Conveyance System> Figure 1 shows the configuration of a transport system 10 according to an exemplary embodiment of the present disclosure. The transport system 10 is equipment for transporting material 100, and as a process performed while transporting, the configuration in Figure 1 allows for heat treatment of the material 100 as an example. In the drawings from Figure 1 onward, the transport direction is denoted as the Z direction, the horizontal direction as the X direction, and the vertical direction as the Y direction. The X, Y, and Z directions are orthogonal to each other.

[0023] The material to be conveyed 100 is a cylindrical material that extends with the conveying direction as its longitudinal direction. Cylindrical materials include, for example, metal pipes such as steel pipes. However, the material to be conveyed 100 is not limited to cylindrical materials; it may also be a solid material such as a round bar. In other words, the material to be conveyed 100 only needs to have a circular outer shape when viewed in the conveying direction.

[0024] The transport system 10 comprises turning rolls 1A, 1B, induction heating device 2, outer diameter sensor 3, laser Doppler velocometer 4, mirror 5, motors 6A, 6B, PLG (pulse generators) 7A, 7B, inverters 8A, 8B, and calculation unit 9.

[0025] Turning roll 1A is positioned on the upstream side in the conveying direction, and turning roll 1B is positioned on the downstream side in the conveying direction. Multiple turning rolls 1A and 1B are arranged in the conveying direction at an angle to form skew rolls. The material to be conveyed 100 is conveyed by turning rolls 1A and 1B in a skew direction. In skew conveying, the material to be conveyed 100 rotates in the circumferential direction (around a central axis extending in the longitudinal direction) while being conveyed in a straight line in the conveying direction.

[0026] The induction heating device 2 performs induction heating on the material to be conveyed 100 using a heating coil 21 to carry out the heating treatment. The heating coil 21 is positioned on the exit side of the downstream turning roll 1A and on the inlet side of the upstream turning roll 1B. The material to be conveyed 100, which has been conveyed downstream from the downstream turning roll 1A, passes through the heating coil 21 and is conveyed to the upstream turning roll 1B.

[0027] The outer diameter sensor 3 is positioned between the turning rolls 1A, which are aligned in the conveying direction. The outer diameter sensor 3 is a sensor that detects the outer diameter coordinates of the material being conveyed 100 by the turning rolls 1A. The outer diameter sensor 3 is used to measure the center coordinates (coordinates of the central axis) of the material being conveyed 100, but details will be described later.

[0028] The laser Doppler velocometer 4 and mirror 5 are positioned near the outer diameter sensor 3. The laser Doppler velocometer 4 utilizes the laser Doppler effect to measure the transport speed (straight-line speed in the transport direction) of the transported material 100, which is being transported by the turning roll 1A, based on the reflected light obtained by irradiating the material with a laser. The laser Doppler velocometer 4 can detect only the straight-line speed component of the transported material 100, regardless of the circumferential speed component, by mounting it in a predetermined orientation.

[0029] Mirror 5 is a mirror that reflects the laser emitted from the laser Doppler velocometer 4 toward the transported material 100. The angle of Mirror 5 can be adjusted to make the laser follow the transported material 100. The control of the laser Doppler velocometer 4 and Mirror 5 will be described later.

[0030] Motors 6A and 6B rotate turning rolls 1A and 1B, respectively. PLG7A and 7B generate pulse signals representing the rotational speed of motors 6A and 6B, respectively. Inverters 8A and 8B control the rotational speed of motors 6A and 6B based on the pulse signals output from PLG7A and 7B, respectively.

[0031] The calculation unit 9 generates a speed command based on the measurement result of the transport speed by the laser Doppler velocometer 4 and sends the speed command to inverters 8A and 8B.

[0032] <Conveyor Speed ​​Measurement Device> Figure 2 shows the configuration of the transport speed measuring device 15 included in the transport system 10 described above. The transport speed measuring device 15 includes an outer diameter sensor 3, a laser Doppler velocometer 4, and a mirror 5, as well as a first sensor amplifier 331, a second sensor amplifier 332, a controller 11, a rotary drive mechanism 12, a linear drive mechanism 13, and a display 14.

[0033] <<About center coordinate detection>> In a conveying system 10 that performs skew conveying, if the conveyed material 100 has a bend in the longitudinal direction, eccentric rotation occurs in the conveyed material 100, causing it to sway in the vertical and horizontal directions. The conveying speed measuring device 15 is capable of measuring the center coordinates of the conveyed material 100 as it sways in the vertical and horizontal directions. Here, the method for measuring the center coordinates will be described.

[0034] Figure 3 shows the configuration of the outer diameter sensor 3. Figure 3 is a plan view in a plane perpendicular to the transport direction. The outer diameter sensor 3 includes a first light emitter 311, a first light receiver 321, a second light emitter 312, and a second light receiver 322. The first light emitter 311 and the first light receiver 321 are paired, and the second light emitter 312 and the second light receiver 322 are paired. The first light receiver 321 and the second light receiver 322 are linear sensor type.

[0035] The first light emitter 311 and the first light receiver 321 are arranged opposite each other in the Y direction (vertical direction). Parallel light L1 emitted from the first light emitter 311 is received by the first light receiver 321. The second light emitter 312 and the second light receiver 322 are arranged opposite each other in the X direction (horizontal direction). Parallel light L2 emitted from the second light emitter 312 is received by the second light receiver 322.

[0036] Within the area enclosed by the first light emitter 311, the first light receiver 321, the second light emitter 312, and the second light receiver 322, the material to be transported 100 passes in the transport direction (Z direction). As a result, a portion of the parallel light L1 emitted from the first light emitter 311 is blocked by the material to be transported 100, while the remaining portion reaches the first light receiver 321 without being blocked by the material to be transported 100. Therefore, the amount of light received is small in the region Ax where the material to be transported 100 is projected onto the first light receiver 321 in the Y direction, and large in the region outside of region Ax.

[0037] Similarly, a portion of the parallel light L2 emitted from the second light emitter 312 is blocked by the transported material 100, while the remaining portion reaches the second light receiver 322 without being blocked by the transported material 100. Therefore, the amount of light received is small in region Ay, where the transported material 100 is projected onto the second light receiver 322 in the X direction, and large in the region outside region Ay. Regions Ax and Ay represent the outer diameter region of the transported material 100.

[0038] The light received by the first light receiver 321 is converted into a first light-receiving signal Sr1, which is an electrical signal corresponding to the amount of light received. The first light-receiving signal Sr1 indicates the distribution of the amount of light received in the X direction. The first light-receiving signal Sr1 is input to the first sensor amplifier 331 and output as the first amplifier signal Sa1. The light received by the second light receiver 322 is converted into a second light-receiving signal Sr2, which is an electrical signal corresponding to the amount of light received. The second light-receiving signal Sr2 indicates the distribution of the amount of light received in the Y direction. The second light-receiving signal Sr2 is input to the second sensor amplifier 332 and output as the second amplifier signal Sa2.

[0039] The first amplifier signal Sa1 and the second amplifier signal Sa2 are input to the controller 11. Here, Figure 4 is a diagram showing the internal configuration of the controller 11. The controller 11 has a center coordinate calculation unit 111. Based on the first amplifier signal Sa1 and the second amplifier signal Sa2, the center coordinate calculation unit 111 calculates the center coordinates C(Cx,Cy) (Figure 3) of the material to be transported 100. Specifically, since the X-direction edge coordinates Ex1 and Ex2, which are the position coordinates of both ends of region Ax in the X direction, can be detected as positions where the amount of light received changes abruptly, the X-direction center position Cx between the X-direction edge coordinates Ex1 and Ex2 can be calculated. Similarly, since the Y-direction edge coordinates Ey1 and Ey2, which are the position coordinates of both ends of region Ay in the Y direction, can be detected as positions where the amount of light received changes abruptly, the Y-direction center position Cy between the Y-direction edge coordinates Ey1 and Ey2 can be calculated.

[0040] <<Regarding mirror rotation control>> As shown in Figures 2 and 4, a rotational drive mechanism 12 is provided corresponding to the mirror 5. The rotational drive mechanism 12 rotates the mirror 5. The rotational control of the mirror 5 using such a rotational drive mechanism 12 will now be described.

[0041] As shown in Figure 4, the controller 11 includes a mirror angle calculation unit 112 and a mirror angle control unit 114. The mirror angle calculation unit 112 calculates the mirror angle θ of the mirror 5 based on the calculated center coordinates C(Cx,Cy), such that the laser emitted from the laser Doppler velocometer 4 and reflected by the mirror 5 follows the center coordinates C(Cx,Cy). Note that for the laser to follow the center coordinates C(Cx,Cy), the laser reflected by the mirror 5 is reflected from the outer surface of the material being transported 100, but the center coordinates C(Cx,Cy) are located on the extension of the optical path of the laser reflected by the mirror 5.

[0042] The method for calculating this mirror angle θ will be explained using Figure 5. Figure 5 is a plan view of a plane perpendicular to the transport direction. Let the center coordinates of the transported material 100 at the initial position be C(Cx,Cy)=(a,b). If the laser emitted from the laser Doppler velocometer 4 is reflected at the position of the rotation axis J of the mirror 5 and the angle that the optical path makes with respect to the X direction (X-axis) toward the center coordinates C(Cx,Cy) of the transported material 100 at the initial position is α, then α is expressed by the following formula.

number

[0043] Let the center coordinates C'=(a',b') of the transported material 100' after eccentricity. If β is the angle that the laser beam emitted from the laser Doppler velocometer 4 makes with the X direction (X-axis) of the optical path that is reflected at the rotation axis J of the mirror 5 and heads toward the center coordinates C' of the transported material 100' after eccentricity, then β is expressed by the following formula.

number

[0044] Then, the mirror angle θ of the mirror 5 (the angle of the controlled mirror 5' relative to the mirror 5 at the initial position) for the laser to track the center coordinate C' of the transported material 100 after eccentricity is expressed by the following formula.

number

[0045] The mirror angle θ calculated in this way is input to the mirror angle control unit 114. Here, Figure 6 shows an example of the configuration of the mirror angle control unit 114. The mirror angle control unit 114 includes a deviation calculation unit 114A and a PI (Proportional-Integral) controller 114B. The deviation calculation unit 114A calculates the deviation Δθ between the mirror angle θ (target value) and the mirror angle detection value θfb detected by the rotation drive mechanism 12. The PI controller 114B generates and outputs a control output OUT1 based on the set proportional and integral gains and the deviation Δθ. The rotation drive mechanism 12 (controlled object) rotates the mirror 5 based on the control output OUT1. As a result, the angle of the mirror 5 is controlled to the mirror angle θ.

[0046] As described above, in the transport speed measuring device 15 according to this embodiment, the mirror 5 is angle-controlled so that the laser irradiated from the laser Doppler velocometer 4 follows the central coordinate C of the transported material 100 which sways in the vertical and horizontal directions. This allows the laser to be appropriately reflected by the transported material 100 and returned to the laser Doppler velocometer 4, suppressing the laser Doppler velocometer 4 from going out of its field of view and improving the accuracy of speed measurement by the laser Doppler velocometer 4. Although the vertical and horizontal swaying of the transported material 100 is specific to skew transport, the present invention can be effectively applied to any transport configuration in which vertical and horizontal swaying occurs, even if it is not skew transport.

[0047] As a method for detecting the center coordinates of the material being transported, one could, for example, install a camera in the direction from which the material is approaching and use the camera to photograph the end face of the material. However, this method is limited by the fact that the detection response speed must be sufficient relative to the rotational speed of the material being measured. Another limitation is that the material being transported must not be bent. If the material being transported is bent, the center coordinates of the end face of the material being transported will be misaligned with the center coordinates of the point where the laser is irradiated by the laser Doppler velocometer. In contrast, the method using an outer diameter sensor, as in this embodiment, eliminates the above limitations.

[0048] <<Regarding Linear Control of Laser Doppler Velocity Meters>> As shown in Figures 2 and 4, a linear drive mechanism 13 is provided in conjunction with the laser Doppler velocometer 4. The linear drive mechanism 13 linearly drives the laser Doppler velocometer 4 closer to or further away from the mirror 5. Linear control of the laser Doppler velocometer 4 using such a linear drive mechanism 13 will be described below.

[0049] As shown in Figure 4, the controller 11 includes a linear target position determination unit 113 and a linear control unit 115. The linear target position determination unit 113 calculates the distance t between the laser Doppler velocometer 4 and the rotation axis J, based on the distance l' (distance between the center coordinate C' of the eccentric transported material 100' and the rotation axis J) obtained in the process of calculating the mirror angle θ in the mirror angle calculation unit 112, such that the optical path length between the laser Doppler velocometer 4 and the eccentric transported material 100' becomes a predetermined target optical path length Lref. The distance t is expressed by the following formula. (t+(l'-r))×2=Lref t = Lref / 2 - (l' - r) However, r is the radius of the material being conveyed 100 (half of its outer diameter).

[0050] The linear target position determination unit 113 outputs the linear position PL of the laser Doppler velocometer 4, corresponding to the distance t calculated in this manner, to the linear control unit 115. Here, Figure 7 shows an example of the configuration of the linear control unit 115. The linear control unit 115 includes a deviation calculation unit 115A and a PI controller 115B. The deviation calculation unit 115A calculates the deviation ΔPL between the linear position PL (target value) and the linear position detection value PLfb detected by the linear drive mechanism 13. The PI controller 115B generates and outputs a control output OUT2 based on the set proportional gain and integral gain and the deviation ΔPL. The linear drive mechanism 13 (controlled object) linearly drives the laser Doppler velocometer 4 based on the control output OUT2. As a result, the linear position of the laser Doppler velocometer 4 is controlled to the linear position PL.

[0051] Here, the gain parameters in the PI controller 115B are set so that the linear position of the laser Doppler velocometer 4 falls within the focal depth of the laser Doppler velocometer 4 (e.g., ±20 mm). As a result, the optical path length between the laser Doppler velocometer 4 and the transported material 100 can be controlled to the target optical path length Lref ± focal depth as the laser tracks the central coordinate C of the transported material 100, thereby stabilizing the measurement by the laser Doppler velocometer 4.

[0052] Furthermore, the display unit 14 (Figure 2) provided on the transport speed measuring device 15 can display the speed measured by the laser Doppler velocometer 4.

[0053] <<Applications of measured conveying speeds>> As described above, the transport speed measuring device 15 according to this embodiment can improve the accuracy of measuring the transport speed of the transported material 100 by the laser Doppler velocometer 4. The transport speed measured with such accuracy can be used for the following applications, for example.

[0054] For example, in the transport system 10 shown in Figure 1, the calculation unit 9 generates a speed command based on the measured transport speed such that the transport speed of the material to be transported 100 remains constant. The inverters 8A and 8B control the speed of the motors 6A and 6B respectively based on the generated speed command. As a result, the speed of the material to be transported 100 passing through the heating coil 21 remains constant, and unevenness in heat treatment can be suppressed.

[0055] For example, when applying a skew conveying system to equipment that performs polishing on the entire circumference of a conveyed material, uneven polishing can be suppressed by controlling the conveying speed of the conveyed material to a constant level based on the conveying speed measured by a laser Doppler velocometer.

[0056] For example, when performing non-destructive testing (flaw detection) while skew-transporting a material, a marking device is installed on the exit side of the skew-transport section. The marking device marks the location where a flaw is detected in the material being transported. By applying the transport speed measuring device according to this embodiment to such equipment, the flaw detection location on the material being transported can be calculated by integrating the accurately measured transport speed. This allows the marking device to accurately mark the location where a flaw is detected, reducing the amount of marking removed. [Explanation of Symbols]

[0057] 1A, 1B Turning Rolls 2 Induction heating device 3. Outer diameter sensor 4. Laser Doppler Velocity Meter 5 Mirror 6A, 6B motors 7A, 7B PLG (Pulse Generator) 8A, 8B Inverter 9 Arithmetic section 10 Conveying Systems 11. Control Unit 12 Rotary drive mechanism 13 Linear drive mechanism 14 Display 15. Conveyor speed measuring device 21 Heating coil 100 Material to be conveyed 111 Center coordinate calculation section 112 Mirror Angle Calculation Unit 113 Linear target position determination unit 114 Mirror Angle Control Unit 114A Deviation calculation section 114B PI controller 115 Linear Control Unit 115A Deviation calculation section 115B PI controller 311 1st Floodlight 312 Second floodlight 321 1st receiver 322 2nd receiver 331 First Sensor Amplifier 332 Second Sensor Amplifier J rotation axis L1,L2 parallel light

Claims

1. A conveying speed measuring device used in a conveying system for conveying a material that has a circular outer shape when viewed in the conveying direction and extends with the conveying direction as its longitudinal direction, A center coordinate measuring unit for measuring the center coordinates of the material to be conveyed, A laser Doppler velocometer and A mirror that reflects the laser emitted from the laser Doppler velocometer and guides it to the material to be transported, A rotational drive mechanism for rotating the aforementioned mirror, A first control unit controls the rotation drive mechanism so that the laser follows the central coordinates, A transport speed measuring device equipped with the following features.

2. The aforementioned central coordinate measuring unit is An outer diameter sensor comprising a first light emitter and a first light receiver arranged opposite to each other in a first direction perpendicular to the transport direction, and a second light emitter and a second light receiver arranged opposite to each other in a second direction perpendicular to the transport direction and the first direction, wherein the transported material is configured to pass through its inner surface. A center coordinate calculation unit calculates the center coordinates based on the light signals output from the first and second light receivers, respectively. A transport speed measuring device according to claim 1, having the following features.

3. The first control unit is, A mirror angle calculation unit calculates the angle of the mirror such that the center coordinates are located on the extension of the optical path of the laser reflected by the mirror, A mirror angle control unit controls the rotation drive mechanism to control the angle of the mirror to a target value which is the calculated angle of the mirror, A transport speed measuring device according to claim 1, having the following features.

4. A linear drive mechanism that linearly drives the laser Doppler velocometer so that the distance between it and the mirror is variable, A second control unit controls the linear drive mechanism so that the optical path length between the laser Doppler velocometer and the transported material becomes a predetermined target value, based on a first distance between the center coordinates and the rotation axis of the mirror obtained in the process of calculating the angle of the mirror in the mirror angle calculation unit. The transport speed measuring device according to claim 3, comprising:

5. The second control unit is, A linear target position determination unit determines the linear target position of the laser Doppler velocometer such that the optical path length becomes the predetermined target value based on the first distance, A linear control unit controls the linear drive mechanism to control the position of the laser Doppler velocometer to the determined linear target position, A transport speed measuring device according to claim 4, having the following features.

6. The transport speed measuring device according to claim 4, wherein the second control unit controls the optical path length to be a predetermined target value ± depth of field.

7. The conveying system is configured to skew the conveyed material, as described in any one of claims 1 to 6, for the conveying speed measuring device.

8. A method for measuring the conveying speed used in a conveying system that conveys a material to be conveyed, which has a circular outer shape when viewed in the conveying direction and extends with the conveying direction as its longitudinal direction, A first step is to measure the central coordinates of the material to be transported, A second step is to calculate the angle of the mirror such that the center coordinates are located on the extension of the optical path through which the laser emitted from the laser Doppler velocometer is reflected by the mirror and guided to the material to be transported, A third step involves controlling a rotational drive mechanism that rotates the mirror so as to control the angle of the mirror to a target value which is the calculated angle of the mirror. A method for measuring conveying speed, including the method described above.

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