Grinding system, grinding method and method for manufacturing steel product

Abstract

To provide a grinding system, a grinding method and a manufacturing method for s steel product, each enabling materialization of efficient grinding.SOLUTION: A grinding system comprises: a shape measurement device which measures a three-dimensional shape and a posture of a grinding-target material; a detection device which detects a position and a shape of a grinding-target portion existing on a surface of the grinding-target material; a grinding device (6) comprising a grinder which grinds the grinding-target portion; a movement mechanism which moves the grinding-target material relatively with respect to the shape measurement device and the grinding device; a grinder control device (5) which generates a track for the grinder for grinding the grinding-target portion, on the basis of the three-dimensional shape and the posture of the grinding-target material measured by the shape measurement device and controls the grinding device in such a manner that the grinder moves along the track; and a movement mechanism control device (12) which when the shape measurement device measures the grinding-target material and when the grinder grinds the grinding-target portion, controls the movement mechanism in such a manner that the grinding-target material moves relatively with respect to the shape measurement device and the grinding device.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a grinding system, a grinding method, and a manufacturing method for a steel product. The present disclosure particularly relates to a grinding system, a grinding method, and a manufacturing method for a steel product for removing defects present on the surface of a product such as a steel pipe, a steel bar, or a round bar. [Background technology]

[0002] In the manufacture of steel pipes or steel bars, defects (flaws) may occur on the outer surface of the product. Since defects occur at random positions on the outer surface of the product and the shapes of the products vary, conventionally, defects are often removed manually by grinding with a grinder.

[0003] As a method for automatically removing defects, for example, Patent Document 1 discloses a defect grinding system that detects the position of a defect in a target material, generates a trajectory for a grinding tool to grind the defect, and moves the grinding tool along the trajectory to grind the defect. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7248148 Summary of the Invention [Problem to be solved by the invention]

[0005] According to Patent Document 1, defects (flaws) present at various positions can be ground and removed. Here, for example, when the target material is a long cylindrical product such as a steel pipe, a steel bar, or a round bar, linear defects may exist over a wide area. In addition, defects may exist beyond the movable range of the grinding device (for example, a range of about 180° that the grinding device faces). There has been a demand for a method that can efficiently grind such defects without relying on human labor. Here, efficient grinding refers to grinding that is performed with fewer measurements or grinding times for one defect than in the conventional technology.

[0006] An object of the present disclosure, made in consideration of the above circumstances, is to provide a grinding system, a grinding method, and a manufacturing method for steel products that enable efficient grinding. [Means for solving the problem]

[0007] (1) A grinding system according to an embodiment of the present disclosure, A shape measuring device for measuring the three-dimensional shape and orientation of a workpiece; A detection device for detecting the position and shape of a portion to be ground that is present on the surface of the workpiece; a grinding device including a grinding tool for grinding the grinding target portion; a moving mechanism that moves the workpiece relative to the shape measuring device and the grinding device; a grinding tool control device that generates a trajectory of the grinding tool for grinding the portion to be ground based on the three-dimensional shape and orientation of the workpiece measured by the shape measuring device and the position and shape of the portion to be ground detected by the detection device, and controls the grinding tool so that the grinding tool moves along the trajectory; and a movement mechanism control device that controls the movement mechanism so that the workpiece moves relative to the shape measuring device and the grinding device when the shape measuring device measures the workpiece and when the grinding target portion is ground by the grinding tool.

[0008] (2) As an embodiment of the present disclosure, in (1), The workpiece is a circular material having a circular axial cross section.

[0009] (3) As an embodiment of the present disclosure, in (1) or (2), The moving mechanism includes: a rotation mechanism that moves a circumferential position of the workpiece relative to the shape measuring device and the grinding device; and a slide mechanism that moves the axial position of the workpiece relative to the shape measuring device and the grinding device.

[0010] (4) As an embodiment of the present disclosure, in any one of (1) to (3), The movement mechanism control device relatively moves the circumferential and axial positions of the workpiece based on the position and shape of the portion to be ground.

[0011] (5) As an embodiment of the present disclosure, in any one of (1) to (4), When the size of the grinding target part is larger than the movable range of the grinding tool, the grinding tool control device generates a trajectory within the movable range and controls the grinding device so that the grinding tool moves along the trajectory; The movement mechanism control device determines the relative movement amounts of the circumferential and axial positions of the workpiece based on the size of the portion to be ground and the movable range of the grinding tool.

[0012] (6) As an embodiment of the present disclosure, in any one of (1) to (5), The movement mechanism control device determines the relative movement amount of the circumferential position and axial position of the workpiece by prioritizing the larger sized portion to be ground and excluding other portions to be ground that overlap with the larger sized portion to be ground.

[0013] (7) A grinding method according to an embodiment of the present disclosure, a shape measuring process for measuring a three-dimensional shape and attitude of a workpiece by a shape measuring device; a detection step of detecting a position and a shape of a portion to be ground that is present on a surface of the workpiece; a grinding process for generating a trajectory along which a grinding tool of a grinding device moves, based on the measured three-dimensional shape and attitude of the workpiece and the detected position and shape of the portion to be ground, and moving the grinding tool along the trajectory to grind the portion to be ground, In the shape measuring step and the grinding step, the workpiece is moved relative to the shape measuring device and the grinding device.

[0014] (8) A method for producing a steel product according to an embodiment of the present disclosure includes: (7) The grinding method is used to grind the portion to be ground on the surface of the steel product, which is the workpiece. Effect of the Invention

[0015] According to the present disclosure, it is possible to provide a grinding system, a grinding method, and a method for manufacturing steel products that enable efficient grinding. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing an overview of a grinding system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram showing an example of a defect in the present disclosure. [Figure 3A] FIG. 3A is a diagram showing the marking positions and grinding rotation positions. [Figure 3B] FIG. 3B is a diagram showing a process flow of the grinding method. [Figure 4A] FIG. 4A is a diagram for explaining the carriage position calculation. [Figure 4B] FIG. 4B is a diagram for explaining the carriage position calculation. [Figure 4C] FIG. 4C is a diagram for explaining the carriage position calculation. [Diagram 5] FIG. 5 is a diagram showing a circumferential marking detection flow. [Figure 6] FIG. 6 is a diagram showing an outline of a circumferential development. [Figure 7A] FIG. 7A is a diagram for explaining a method for determining a cutout range of a peripheral development view. [Figure 7B] FIG. 7B is a diagram showing a geometric model for calculating the angle of the workpiece. [Figure 8A] FIG. 8A is a diagram showing a cutout area on a two-dimensional image. [Figure 8B] FIG. 8B is a diagram showing the created circumferential development view. [Figure 9A] FIG. 9A is a diagram showing detection of a marking. [Figure 9B] FIG. 9B is another diagram illustrating detection of the markings. [Figure 9C] Figure 9C is another diagram showing the detection of markings. [Figure 9D] Figure 9D is another diagram showing the detection of markings. [Figure 9E] Figure 9E is another diagram showing the detection of markings. [Figure 9F] Figure 9F is another diagram showing the detection of markings. [Figure 9G] Figure 9G is another diagram showing the detection of markings. [Figure 9H] Figure 9H is another diagram showing the detection of markings. [Figure 9I] Figure 9I is another diagram showing the detection of markings. [Figure 10] Figure 10 is a diagram showing the flow of rotation to the grinding rotation position i. [Figure 11] Figure 11 is a diagram showing the flow from three-dimensional imaging to trajectory generation. [Figure 12] Figure 12 is a diagram showing the flow of executing the grinding operation at the grinding rotation position i. [Figure 13] Figure 13 is a diagram explaining the effect of reducing the number of workers.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, with reference to the drawings, a grinding system, a grinding method, and a method for manufacturing a steel product according to an embodiment of the present disclosure will be described. In each figure, the same or corresponding parts are denoted by the same reference numerals. In the description of this embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate.

[0018] Conventionally, to remove defects occurring over a wide area of ​​a workpiece, for example a circular material, a human worker performs grinding work while moving or rotating the workpiece. Even in a system that automates defect removal, the work is considered by dividing it into the following elements. When analyzing grinding work performed by a worker, the grinding work includes (element 1) identifying the location of the defect in the longitudinal direction of the workpiece, (element 2) identifying the location of the defect in the circumferential direction of the workpiece, and (element 3) removing the defect by pressing a grinding tool against the defective position. Below, the system etc. will be explained while dividing the work into such elements as appropriate.

[0019] (Overall system configuration) 1 shows an overview of the grinding system according to this embodiment. The grinding system is a system for removing defects present on the surface of a workpiece 1, and includes a shape measuring device, a detection device, a grinding device, a moving mechanism, a grinding tool control device, and a moving mechanism control device 12. The detection device, the grinding tool control device, and the moving mechanism control device 12 may be configured, for example, by one computer or multiple computers connected via a network.

[0020] In this embodiment, the workpiece 1 is, for example, a circular material having a circular cross section in the axial direction, specifically, a cylindrical long member such as a steel pipe, etc. On the surface of the workpiece 1, there is a grinding target portion 2 such as a defect to be ground.

[0021] In this embodiment, a three-dimensional shape measuring device 3 (an example of a shape measuring device) measures the three-dimensional shape and orientation of a workpiece 1. The three-dimensional shape measuring device 3 is a measuring device that can simultaneously obtain two-dimensional image information, generally called a 3D camera, and three-dimensional point cloud (solid) information.

[0022] In this embodiment, an image processing device 4 (an example of a detection device) detects the position and shape of the grinding target portion 2 present on the surface of the workpiece 1. The image processing device 4 detects the position and shape of the grinding target portion 2 by processing images captured by the three-dimensional shape measuring device 3. For the image processing, a known method using a machine learning model such as deep learning may be used.

[0023] Here, the grinding device is a device equipped with a grinding tool for grinding the part to be ground 2. The grinding tool control device is a device for controlling the grinding device. The grinding tool control device generates a trajectory of the grinding tool for grinding the part to be ground 2 based on the three-dimensional shape and posture of the workpiece 1 and the position and shape of the part to be ground 2, and controls the grinding tool to move along the trajectory. In this embodiment, a robot operation control device 5 (an example of a grinding tool control device) performs inverse kinematic calculation based on the position of the part to be ground 2 detected by the image processing device 4. In this embodiment, a motion trajectory of the articulated robot 6 (an example of a grinding device) is generated such that a grinding wheel 8 (an example of a grinding tool) provided on the grinder 7 is pressed against the position of the part to be ground 2. The articulated robot 6 operates according to the generated motion trajectory, and the grinding wheel 8 comes into contact with the workpiece 1 to grind the part to be ground 2. At this time, a grinding reaction force measuring device 9 may measure the reaction force generated in the grinder 7. The robot operation control device 5 may control the operation of the articulated robot 6 so as to press or release (release) the grindstone 8 so that the measured reaction force becomes a target reaction force in grinding.

[0024] The grinding system according to the present embodiment includes a moving mechanism for moving the workpiece 1 relative to the three-dimensional shape measuring device 3 and the articulated robot 6. The moving mechanism may include a rotation mechanism for rotating the workpiece 1 relative to the three-dimensional shape measuring device 3 and the articulated robot 6, and a slide mechanism for moving the workpiece 1 relative to the three-dimensional shape measuring device 3 and the articulated robot 6 in a direction different from the rotation direction. In the present embodiment, the grinding system has a moving carriage 10 (an example of a slide mechanism) for moving the articulated robot 6 in the axial direction of the workpiece 1 relative to the workpiece 1 as the moving mechanism. In the present embodiment, the grinding system has a turning roller 11 (an example of a rotation mechanism) for rotating the workpiece 1 in the circumferential direction of the workpiece 1 relative to the three-dimensional shape measuring device 3 and the articulated robot 6 as the moving mechanism. Here, the three-dimensional shape measuring device 3 can also be moved in the axial direction of the workpiece 1 by a slide mechanism (not shown). In the present embodiment, the three-dimensional shape measuring device 3 moves in the axial direction of the workpiece 1 in conjunction with the moving carriage 10 (i.e., in conjunction with the articulated robot 6). In this way, the measurement range of the three-dimensional shape measuring device 3 and the movable range of the articulated robot 6 are linked to each other.

[0025] In the example of FIG. 1, the articulated robot 6 is installed on a moving carriage 10 that can move in the axial direction of the workpiece 1. The workpiece 1 is installed on a turning roller 11 so as to be rotatable around its axis. The moving carriage 10 and the turning roller 11 are controlled by a moving mechanism control device 12. The moving mechanism control device 12 can freely adjust the position of the articulated robot 6 in the axial direction (longitudinal direction) relative to the workpiece 1 by using the moving carriage 10. The moving mechanism control device 12 can also freely adjust the angle (rotation angle) of the workpiece 1 around its axis relative to the three-dimensional shape measuring device 3 and the articulated robot 6 by rotating the workpiece 1 by using the turning roller 11. The moving mechanism control device 12 controls the moving mechanism so that the workpiece 1 moves relative to the three-dimensional shape measuring device 3 and the articulated robot 6 when the workpiece 1 is measured by the three-dimensional shape measuring device 3 and when the grinding target portion 2 is ground by the grinding wheel 8. The movement mechanism control device 12 may relatively move the circumferential position and the axial position of the workpiece 1 based on the position and shape of the portion to be ground 2. Although details will be described later, when the size of the portion to be ground 2 is larger than the movable range of the grinding wheel 8, the movement mechanism control device 12 may determine the relative movement amount of the circumferential position and the axial position of the workpiece 1 based on the size of the portion to be ground 2 and the movable range of the grinding wheel 8.

[0026] FIG. 2 is a diagram showing an example of a defect in the present disclosure. The portion 2 to be ground may be a defect itself present on the surface of the workpiece 1 (see the upper diagram in FIG. 2), or may be a marking applied so as to include a defect as in this embodiment. The type, shape, and dimensions of the portion 2 to be ground are not limited to a specific one. In this embodiment, a marking is applied to a defect detected by non-destructive inspection (NDI) performed on a line separate from the grinding line, and then the workpiece 1 is sent to the grinding line. Then, in this embodiment, grinding is performed with the marking on the workpiece 1 as the "portion to be ground 2."

[0027] (Grinding method) 3A shows an image of the marking positions and the grinding rotation positions for grinding by the turning roller 11. Using logic described below, the grinding rotation angles θpi (i=0 to N, N is the number of grinding rotation positions, i.e., the number of markings) corresponding to each marking in the circumferential direction are calculated. By rotating by θpi from the initial position (i=0) by the turning roller 11, the markings are set to be in the optimal positions (i.e., within the movable range of the articulated robot 6, which is the grinding device, and within the measurement range of the three-dimensional shape measuring device 3).

[0028] Here, the grinding system can execute a grinding method for grinding a portion to be ground 2 on the surface of a steel product, which is a workpiece 1, in a manufacturing method for steel products. The grinding method executed by the grinding system has a shape measuring step, a detection step, and a grinding step, and in the shape measuring step and the grinding step, the workpiece 1 is moved relative to the shape measuring device and the grinding device. Here, the shape measuring step is a step of measuring the three-dimensional shape and attitude of the workpiece 1 by the shape measuring device. The detection step is a step of detecting the position and shape of the portion to be ground 2 present on the surface of the workpiece 1. Also, the grinding step is a step of generating a trajectory along which a grinding tool of the grinding device moves based on the measured three-dimensional shape and attitude of the workpiece 1 and the detected position and shape of the portion to be ground 2, and moving the grinding tool along the trajectory to grind the portion to be ground 2.

[0029] FIG. 3B shows an example of a specific process flow of such a grinding method. First, the position of the marking in the axial direction of the workpiece 1 is obtained. The position of the marking may be obtained, for example, by measuring the surface of the workpiece 1 with the three-dimensional shape measuring device 3, or may be obtained using an external sensor separate from the three-dimensional shape measuring device 3. With reference to the obtained marking positions in the longitudinal direction of the workpiece 1, the number of carriage positions (the number of positions to which the movable carriage 10 moves) M and the carriage position Lpk (k=0 to M) are calculated (step S1). The carriage position Lp0 (k=0) is the initial position.

[0030] The movable carriage 10 moves to each calculated position (step S2). That is, the grinding system moves the three-dimensional shape measuring device 3 and the articulated robot 6. Then, at each position, the three-dimensional shape measuring device 3 detects markings in the circumferential direction of the workpiece 1 (step S3), and the number N of required grinding rotation positions and the grinding rotation angle θpi of each marking are calculated.

[0031] The turning roller 11 is rotated based on the calculated angle information so that the workpiece 1 is placed at an appropriate grinding rotation position i (step S4). The workpiece 1 is 3D measured by the 3D shape measuring device 3, a processing trajectory is generated based on the shape, and grinding is performed (step S5). The grinding is repeated the number of grinding rotation positions N (No in step S6), and when grinding is completed at all grinding rotation positions i (Yes in step S6), the carriage moves to the next position (carriage position). The carriage moves the number of carriage positions M (No in step S7), and steps S2 to S6 are repeated. When grinding is completed at all carriage positions k (Yes in step S7), grinding of one workpiece 1 is completed.

[0032] As described above, in the present embodiment, in the shape measuring process and the grinding process, the workpiece 1 is moved relative to the three-dimensional shape measuring device 3 and the articulated robot 6. As a result, even if a defect exists outside the measurement range of the three-dimensional shape measuring device 3 and outside the movable range of the articulated robot 6, the defect can be detected and ground by moving the workpiece 1 relatively, enabling efficient grinding.

[0033] (Position calculation of the moving cart 10) FIG. 4A is a diagram for explaining the carriage position calculation, showing an image of the marking position and the shooting range. The distance from the longitudinal origin to the marking start position is Lsk (k=0 to M), and the size of the marking is Lk. Markings that overlap in the longitudinal direction (axial direction of the workpiece 1) are considered to be one marking. Table 1 lists each marking and combinations of multiple markings, and for markings larger than Lm, which is the shooting range of the three-dimensional shape measuring device 3 in one shot, the long marking flag is set to "1", and the rest are set to "0". The end position Lek of marking k is calculated using formula (1).

[0034] Lek=Lk+Lsk … Equation (1)

[0035] [Table 1]

[0036] Furthermore, the notation and position of multiple markings (combinations of multiple markings) use the format and calculation formula shown in Table 2. For example, multiple markings with a marking No. of "1-2" refer to a combination of markings "1" and "2". Hereinafter, the marking position processing flow will be explained using this marking list as an example. The marking position processing flow corresponds to the detailed flow of step S1 in FIG. 3B.

[0037] [Table 2]

[0038] (Step 1) As shown in Table 3, a column “1-shot grinding range ranking” is added in which markings with the long marking flag set to “0” are ranked in descending order of length.

[0039] [Table 3]

[0040] (Step 2) The carriage position Lp1 is calculated for the marking with the first place "one shot grinding range ranking" as shown in Table 4. When the first place marking is marking k, the carriage position Lp1 is calculated by formula (2).

[0041] Lp1=Lsk+Lk / 2 … Equation (2)

[0042] [Table 4]

[0043] (Step 3) As shown in Table 5, a process is performed to delete combinations or single markings included in the marking with the No. 1 "one shot grinding range ranking." In other words, a process is performed to delete markings that overlap with large size markings.

[0044] [Table 5]

[0045] (Step 4) As shown in Table 6, the carriage position Lp2 of the marking with the next largest "1-shot grinding range ranking" is calculated using formula (2). However, Lp1 in formula (2) should be read as Lp2.

[0046] [Table 6]

[0047] (Step 5) The above steps (step 2) to (step 4) are repeated until there are no markings other than the long marking flag (for all markings whose long marking flag is "0"). If there are no long marking flags, the process of calculating the position of the movable carriage 10 ends.

[0048] (Step 6) Here, as shown in FIG. 4B, the dolly positions Lpk and Lpn are adjusted so that the center of the single marking or multiple markings coincides with the center of the imaging range.

[0049] (Step 7) Calculations are performed for the remaining long markings as shown in Table 7. Also, as shown in FIG. 4C, ΔLp may be set as the overlapping margin between the photographing range and the grinding range of the long markings. At this time, the number of grinding times Sk of the long markings, the total grinding range Lpak, the grinding start position Lpask, and each grinding position Lpkn (n=1 to Sk) are calculated using formulas (3) to (6). Here, Sk in formula (3) is rounded up and given as an integer.

[0050] Sk=(Li+ΔLp) / Lm … Equation (3) Lpak=Lm+(Sk-1)(Lm-ΔLp) … Equation (4) Lpask=(Lpak-Li) / 2 … Equation (5) Lpkn=Lsi-Lpask+n(Lm-ΔLp) / 2 … Formula (6)

[0051] [Table 7]

[0052] (Step 8) In Table 8, the trolley positions Lpk for all individual or multiple markings are calculated.

[0053] [Table 8]

[0054] (Step 9) In Table 9, the list is organized as a list of only the bogie position Lp, multiple marking flags, and long marking flags, and then arranged in ascending order of Lpk.

[0055] [Table 9]

[0056] (Step 10) As shown in Table 10, when multiple long markings exist, a process may be performed to align the flag numbers of each long marking.

[0057] [Table 10]

[0058] Here, by executing the process of step 3, the movement mechanism control device 12 can determine the relative movement amount of the axial position of the workpiece 1 by prioritizing the large-sized portion to be ground 2 (marking) and excluding other portions to be ground 2 that overlap with the large-sized portion to be ground 2. The same process is also performed for the circumferential position. Therefore, the grinding system according to this embodiment enables efficient grinding.

[0059] (Method of detecting circumferential markings) FIG. 5 shows the circumferential marking detection flow, i.e., the detailed flow of step S3 in FIG. 3B. First, the creation range of the "circumferential development" is specified. Next, the rotation time ttr of the turning roller 11 is calculated, and a turning roller rotation start command is output. At the same time, a continuous shooting command is issued to the three-dimensional shape measuring device 3, and the circumferential development creation process is performed until the rotation time ttr has elapsed by the timer. After ttr has elapsed, a turning roller rotation stop command is issued, the marking is detected from the created circumferential development, the position is calculated, and the number of grinding rotation positions N and the grinding rotation angle θpi are determined. Then, the turning roller 11 is rotated so that the workpiece 1 is at the appropriate grinding rotation position i based on the determined angle information.

[0060] FIG. 6 is a diagram showing an overview of a circumferential development view. While continuously rotating the workpiece 1, two-dimensional images are taken at regular intervals by the three-dimensional shape measuring device 3. As shown in FIG. 6, an image is cut out from a specific location where the workpiece 1 appears in the taken image, and these cut-out images are arranged in the order of shooting to create a circumferential development view. The circumferential development view is a diagram in which the longitudinal position of the workpiece 1 is plotted on the horizontal axis and the angular position is plotted on the vertical axis. The marking position is calculated from the circumferential development view. The excess part in FIG. 6 is an overlapping part obtained by rotation exceeding 360°.

[0061] FIG. 7A is a diagram for explaining a method of determining a cutting range of a circumferential development view, and shows the relationship between an image of a taken two-dimensional image and parameters for determining which position on the image is to be cut out. The workpiece position (upper) pU and the workpiece position (lower) pL in the image serving as a reference for the cutting position are calculated by formulas (7) and (8).

[0062] pU = a1×Dp + b1... Formula (7) pL = a2×Dp + b2... Formula (8)

[0063] Here, Dp is the diameter of the workpiece. The diameter Dpp of the workpiece on the pixel is calculated from formula (9).

[0064] Dpp = pU - pL... Formula (9)

[0065] The cutting position (upper) ys and the cutting position (lower) ye on the image are calculated by formulas (10) and (11).

[0066] ys = pU + Dpp×cU... Formula (10) ye = pU + Dpp×cE... Formula (11)

[0067] Here, a1, b1, a2, and b2 are arbitrary coefficients, but for example, they are determined by taking pictures of the workpiece 1 in multiple patterns with different diameters, plotting the top and bottom positions of each image, and finding them as a function of Dp using the least squares method. cU and cE are ratio parameters between 0 and 1, and are parameters that determine which height position of the workpiece 1 in the image is to be cut out. They are set so that the relationship cE>cU is satisfied. Figure 7B shows a geometric model for calculating the angle of the workpiece 1. The angle and arc length of the area reflected on the surface of the workpiece 1 are calculated by pU, pL, ys, and ye. The angle θa to the cutout position (upper) ys and the angle θb to the cutout position (lower) ye are calculated by equations (12) and (13), with the upper position of the workpiece 1 reflected in the image taken by the three-dimensional shape measuring device 3 being 0°.

[0068] θa=cos -1 {(50-cU) / 50} … Equation (12) θb=cos -1 {(50-cU-cE) / 50} … Equation (13)

[0069] In addition, using the angle obtained by the above formula, the cutout angle range θr and the cutout arc length ΔR are calculated from formulas (14) and (15).

[0070] θr=a4×θb-a3×θa … Equation (14) ΔR=Dp / 2×θs … Equation (15)

[0071] Here, a3 and a4 are parameters that can be arbitrarily set and are desirably set in the range of 0 to 2. a3 and a4 are parameters that complement the error between the reality and the geometric model, and are appropriately changed according to the values ​​of cU, cE, etc.

[0072] FIG. 8A shows the cutout range on a two-dimensional image. As shown in the figure, when the vertical axis of the image is the y axis and the horizontal axis is the x axis, the cutout range is defined as a rectangle with two points, (xs, ys) and (xe, ye), as diagonal vertices. ys and ye are calculated using equations (10) and (11). xs and xe are set based on the range that can be photographed by the three-dimensional shape measuring device 3 and the range in which the articulated robot 6 can operate. Here, when the x-direction positions of xs and xe in the three-dimensional space are xs3 and xe3, the above-mentioned photographing range Lm is set according to equation (16) for consistency.

[0073] Lm=xe3-xs3 … Formula (16)

[0074] Furthermore, when the rotational peripheral speed of the workpiece 1 is V, the photographing interval tc and the rotation time ttr during photographing are calculated by equations (17) and (18).

[0075] tc=ΔR / V(s) … Equation (17) ttr=tc(360+α) / θr … Equation (18)

[0076] α is a margin for creating a circumferential development view, and it is desirable to set a value of 360° or more.

[0077] Fig. 8B shows the created peripheral development. While the workpiece 1 rotates at a peripheral speed V, images are taken for a rotation time ttr at intervals tc, and the images cut out from the range determined by (xs, ys) and (xe, ye) are arranged in the order of taking the images, thereby creating a peripheral development.

[0078] 9A to 9I are diagrams showing detection of markings of various patterns. First, FIG. 9A illustrates the marking positions in the peripheral development. In this embodiment, the horizontal axis of the peripheral development is set to the longitudinal position L, the vertical axis is set to the angular position, and the upper left corner is called the 0 point. The angular position of the marking existence start position from the 0 point of the i-th marking (shown as marking i) is θsi, and the angular range of existence is θi. In addition, the longitudinal position of the marking existence start position from the 0 point is Lsi, and the longitudinal range of existence is Li. Table 11 is a list of markings that exist in the peripheral development. At this time, a marking with θsi≧360° (marking 2 in FIG. 9A) is excluded from the list as a duplicated marking.

[0079] [Table 11]

[0080] FIG. 9B shows an example of a circumferential development diagram in which a small-sized marking exists alone. Here, θm in the diagram is the smaller value of the angle range that can be photographed by the three-dimensional shape measuring device 3 in one shot or the movable range of the articulated robot 6. Here, a marking in the angle range θ>θm is considered to be a large marking, and the large marking flag is set to "1". For markings that are not large markings, the large marking flag is set to "0". Here, the marking end position θei, Lei are calculated by equations (19) and (20). Also, the grinding rotation angle θpi at the grinding rotation position i is calculated by equation (21).

[0081] θei=θsi+θi … Equation (19) Lei=Lsi+Li … Equation (20) θpi=θsi+θi / 2 … Equation (21)

[0082] Table 12 shows a list of markings. This list includes the angular position, longitudinal position (axial position) and marking flag of each marking calculated by equations (19) to (21), and is created for each carriage position of the mobile carriage 10. In the example of Table 12, there is only one line because there is a single marking, but in the case of multiple markings described below, the list will have multiple lines.

[0083] [Table 12]

[0084] FIG. 9C shows an example where there are multiple small markings. Table 13 shows a list of these markings. Table 14 shows the definitions of the angles and positions of the multiple markings (how the values ​​are determined). Table 15 shows the organized list of multiple markings. The markings in the list are organized in the following procedure.

[0085] [Table 13]

[0086] [Table 14]

[0087] [Table 15]

[0088] A flag (grinding possibility flag in 1 position) is set for markings that can be ground in 1 position, i.e., without rotating the workpiece 1. If the large marking flag is "1", i.e., θi>θm, the grinding possibility flag in 1 position becomes "0". Conversely, if θi≦θm, the grinding possibility flag in 1 position becomes "1".

[0089] Next, the markings whose grinding possibility flag at position 1 is "1" are ranked by the existence range angle. The marking with the largest existence range angle (largest size) is set to the first place.

[0090] As in step 3 of the above cart position calculation, a process is performed to delete large markings and overlapping markings. For the other markings, the process of selecting the marking with the largest existence range angle and deleting overlapping markings is repeated until all grinding possibility flags at one position become "1". Here, the grinding order is set in ascending order of grinding angle (rotation angle) θp.

[0091] FIG. 9D shows an example where a small marking exists between multiple small markings. Table 16 shows the marking list. In this example, a small marking (4) exists between multiple valid markings (2-3). If the range angle of a small marking is included in the range angle of a large marking, the small marking can be ignored (deleted) because they can be ground together. This allows for more efficient grinding.

[0092] [Table 16]

[0093] FIG. 9E shows an example of large-sized marking. For markings with a large marking flag of "1", the number of grinding passes Si for the large marking, the total grinding range θpai, the grinding start position θpasi, and each grinding rotation angle θpin (n=1 to Si) are calculated using formulas (22) to (25). Here, it is assumed that Δθp is set as the overlapping margin of the large marking grinding range. Also, Si in formula (22) is rounded up and given as an integer.

[0094] Si=(θi+Δθp) / θm … Equation (22) θpai=θm+(Si-1)(θm-Δθp) … Equation (23) θpasi=(θpai-θi) / 2 … Equation (24) θpin=θsi-θpasi+n(θm-Δθp) / 2 … Equation (25)

[0095] The large markings are ground independently from the other markings. As shown in the list of large markings in Table 17, the large markings have multiple grinding rotation angles θpin (n=1 to Si) for one marking.

[0096] [Table 17]

[0097] FIG. 9F shows a circumferential development of a pattern in which large and small markings exist. Table 18 shows a marking list. For the large marking, the grinding angle calculated by formulas (22) to (25) is used, regardless of the presence of other markings.

[0098] [Table 18]

[0099] FIG. 9G shows a circumferential development of a marking pattern where θsi is 0. In this way, the marking where “θsi=0” is a duplicated marking is ignored. Table 19 shows the marking list in this case.

[0100] [Table 19]

[0101] Figure 9H shows a circumferential development of the diagonal marking pattern. Table 20 shows the marking list.

[0102] [Table 20]

[0103] The calculation for setting the grinding range of the oblique marking is explained below. First, the contour length Lci of the marking i determined to be a large marking is calculated.

[0104] If the condition of the following equation (26) is satisfied, the diagonal marking flag is set to "1".

[0105] (Li+θi) / (Lci / 2)>ac … Equation (26)

[0106] Here, ac is a diagonal marking determination threshold, which is a parameter that can be set arbitrarily. Then, the minimum circumscribing rectangle of the diagonal marking is calculated, and the positions of the four corners of this rectangle (Lr1, θr1), (Lr2, θr2), (Lr3, θr3), and (Lr4, θr4) are calculated.

[0107] Also, a straight line fitting is performed on the bounding rectangle. The reference point of the bounding rectangle is determined by the magnitude of the coefficient a of the fitting straight line function "θ=aL+b". In the example of FIG. 9H, a is a value less than 0. When calculating θ=aL+b1 for one (upper) long side of the bounding rectangle, b1 is calculated using formula (27).

[0108] b1=θr2 / aLr2 … Equation (27)

[0109] Calculations are performed for the reference rectangle assumed as the grinding range. The coordinates (Lr5, θr5) of reference point 1 are calculated using equations (28) and (29), respectively.

[0110] Lr5=(θr5-b1) / a … Equation (28) θr5=θpai+θm / 2 … Equation (29)

[0111] In addition, the coordinates (Lr6, θr6) of reference point 2 are calculated using equations (30) and (31), respectively.

[0112] Lr6=Lr1 … Formula (30) θr6=θr2 … Equation (31)

[0113] The angle range θref and length range Lref of the reference rectangle are calculated by equations (32) and (33), respectively.

[0114] θref=θsi-θpasi+θm-θr2 … Equation (32) Lref=Lr5-Lsi … Formula (33)

[0115] Also, another reference rectangle is set as shown in Fig. 9I. The coordinates (Lr7, θr7) of reference point 3 are calculated by equations (34) and (35), respectively.

[0116] Lr7=Lr3 … Formula (34) θr6=θr4 … Equation (35)

[0117] The total grinding angle range θalli and the total grinding longitudinal range Lalli are calculated by equations (36) and (37), respectively.

[0118] θalli=θr4-θr2 … Equation (36) Lalli = Lr3 - Lr1 … Equation (37)

[0119] The number of grinding passes, Si, is calculated by the formula (38). Si in the formula (38) is rounded up and given as an integer.

[0120] Si=θall / θref … Equation (38)

[0121] The circumferential movement amount θti and the axial movement amount Lti are calculated by equations (39) and (40), respectively.

[0122] θti=(θalli-θref) / (Si-1) … Equation (39) Lti=(Lalli-Lref) / (Si-1) … Equation (40)

[0123] The angle grinding lap allowance Δθri and the position grinding lap allowance ΔLri are calculated by equations (41) and (42), respectively.

[0124] Δθri=θsi-θr2 … Equation (41) ΔLri=Lsi-Lr1 … Formula (42)

[0125] The grinding rotation angle θpin is calculated by equation (43), where j is an integer ranging from 1 to Si.

[0126] θpin=θpai1+(j-1)×θti… Equation (43)

[0127] In the above calculation, a publicly available image processing function or the like may be used. As shown in FIG. 9I, the grinding rotation angle θpin, the angle grinding lap allowance Δθri, the position grinding lap allowance ΔLri, and the axial movement amount Lti are calculated so that the reference rectangle can be overlapped to cover the oblique marking. Table 21 is a marking list including these calculated values.

[0128] [Table 21]

[0129] Table 22 is an example of a final marking list. According to such a marking list, grinding is performed in the order of "diagonal marking", "large marking", "single marking", and "multiple marking". Within the same category, grinding is performed in the order of smallest grinding rotation angle θpi. The number of rows in the marking list is equal to the number of grinding rotation positions N. Based on this list, mask processing for generating the grinding trajectory and movement of the carriage position (additional processing) for large marking and diagonal marking may be performed.

[0130] [Table 22]

[0131] (How to generate a trajectory) Fig. 10 shows the flow of rotation at the grinding rotation position i, which corresponds to the detailed flow of step S4 in Fig. 3B. The turning roller 11 rotates to rotate the workpiece 1 to the grinding rotation angle θpi at the grinding rotation position i. The turning roller rotation angle θti and the rotation time ttri at this time can be calculated by Equation (44) and Equation (45).

[0132] θti=Dp / Dt×(θpi-θp(i-1)) … Equation (44) ttri=θti / V … Equation (45)

[0133] Here, Dt is the turning roller diameter. By issuing a command to the turning roller 11 to rotate for a rotation time ttri, it becomes possible to rotate the workpiece 1 at a desired angle.

[0134] FIG. 11 shows a flow from 3D photography at the grinding rotation position i to trajectory generation, and corresponds to a detailed flow of the process up to step S5 in FIG. 3B just before grinding. First, measurement is performed by the 3D shape measuring device 3. The measured data is in a format in which 3D point cloud (solid) information is linked to a 2D image. First, the range of the marking at the grinding rotation position i is cut out on the 2D image of the measured data. This is to prevent the marking from being mixed with other markings and generating a trajectory. Next, using a known color extraction filter (for example, an HSV color extraction filter), only the marking is extracted on the 2D image. By applying a filter that sets the inside of the range to "1" and the outside of the range to "0", it is possible to extract only the desired color as a binary image. By further applying a median filter, a Gaussian filter, a contour area threshold filter, a scaling filter, or the like to the binary image extracted here, a noise-free binary image of only the marking can be obtained. By cutting out only the part where the marking exists, 3D point cloud data of only the marking can be obtained. Through this series of processes, it is possible to obtain 2D-3D data of the markings only. The trajectory is generated based on this 3D data.

[0135] Here, a further mask may be set. For example, the positions pU, pL of the workpiece 1 on the image are found by the above formula, but a mask may be set so as to cut only an area with a narrower spacing above and below that. For example, a mask may be set from the upper position pU of the workpiece 1 on the image down to the position ymU. Also, for example, a mask may be set from the lower position pL of the workpiece 1 on the image up to ymL. The positions of ymU and ymL on the image may be calculated by formulas (46) and (47).

[0136] ymU=pU+Dpp×(cmU+Dpp×amU) … Equation (46) ymL=pL-Dpp×(cmL+Dpp×amL) … Formula (47)

[0137] Here, cmU, cmL, amU, and aML are parameters that can be set arbitrarily. cmU and cmL are parameters that set the ratio of the mask range to the diameter Dpp of the workpiece 1 on the image. Also, amU and aML are parameters that correct the mask range according to the diameter, and it is desirable to set them between 0 and 1.

[0138] Trajectory generation is performed by setting grinding parameters and arranging "processing control points (control points)" according to the obtained 3D data of only the marking. The grinding parameters are a group of parameters for setting the distance from which part of the 3D point cloud of the marking to place the control points, the interval between the control points, the interval of the "pass" to be ground at one time, the angle and distance at which contact or separation will occur, etc. Each set control point is sent to the articulated robot 6 as trajectory data.

[0139] (Method of controlling grinding tool) FIG. 12 shows the flow of the grinding operation execution at the grinding rotation position i, corresponding to the detailed flow of grinding in step S5 of FIG. 3B. When the trajectory data is transmitted, the articulated robot 6 starts operating. After the articulated robot 6 operates and one grinding is completed, additional processing is required for large markings and diagonal markings. In the case of other markings, the grinding at the grinding rotation position i is completed.

[0140] Additional processing is performed during large marking grinding. Based on the marking information list, the rotation angle θti of the turning roller 11 is determined by Equation (48). Here, j in the equation satisfies 1 < j < Si, indicating the j-th rotation position in the marking at the grinding rotation position i.

[0141] θti = Dp / Dt × (θpij - θpi(j - 1)) … Equation (48)

[0142] After rotating the turning roller 11 by the angle θti, the already created trajectory data is transmitted to the articulated robot 6, and the articulated robot 6 executes the grinding operation. Then, by repeating "rotation of the turning roller 11 and grinding" up to the set number of grinding times Si, it becomes possible to grind large markings by diverting the initially created trajectory. That is, in the case of large markings (when the size of the grinding target part 2 is larger than the movable range of the grinding wheel 8), a trajectory within the movable range of the grinding wheel 8 (within the measurement range of the three-dimensional shape measuring device 3) is generated at the position of the angle θpi1 of the workpiece 1. Then, the articulated robot 6 is controlled so that the grinding wheel 8 moves along the generated trajectory, and grinding is performed. After that, the workpiece 1 is rotated to the angle θpi2, and grinding is performed with the same trajectory as the trajectory created at the position of the angle θpi1. In this way, grinding and rotation are repeated until the workpiece 1 rotates to the angle θpiSi.

[0143] When generating a trajectory, it takes time to perform 3D photography, color extraction processing, and trajectory generation calculations. Therefore, by reusing trajectory data that has been created once, it is possible to grind the large marking efficiently. Here, after grinding Si times, it is necessary to return the rotation of the turning roller 11 to the position where the original trajectory was generated. The rotation angle θre in this case is determined by equation (49).

[0144] θre=-Dp / Dtx(Si-1)θti … Equation (49)

[0145] The turning roller 11 is rotated by θre to complete grinding at the grinding rotation position i.

[0146] In addition, additional processing is performed when grinding the oblique marking. The rotation angle θti of the turning roller 11 based on the marking information list is calculated by formula (48) in the same way as for the large marking.

[0147] After rotating the turning roller 11 by angle θti, the position of the moving carriage 10 is moved by Lti, and the already created trajectory data is sent to the articulated robot 6, which then executes the grinding operation. By repeating "rotation of the turning roller 11, movement of the carriage, and grinding" up to the set number of grinding times Si, it becomes possible to grind the large marking by reusing the initially created trajectory. After grinding Si times, the turning roller 11 is rotated by θre, and grinding at the grinding rotation position i is completed. The rotation angle θre is calculated by equation (49) in the same way as for the large marking.

[0148] (Effect of reduction in number of employees) FIG. 13 is a diagram illustrating the effect of reducing the number of workers. If the number of workers performing grinding work using the grinder 7 before implementing the method of this embodiment is set to 100, the number of workers after implementation was 13. By providing the above-mentioned grinding system, grinding method, and manufacturing method for steel products that enable efficient grinding, and automating the work, it is possible to reduce the number of workers performing grinding work (labor saving). Furthermore, the automation of the work is expected to further improve safety.

[0149] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications or corrections based on the present disclosure. Therefore, it should be noted that these modifications or corrections are included in the scope of the present disclosure. For example, the functions included in each component or each step (process) can be rearranged so as not to be logically inconsistent, and multiple components or steps can be combined into one or divided. The embodiments of the present disclosure can also be realized as a program executed by a processor included in the device or a storage medium on which a program is recorded. It should be understood that these are also included in the scope of the present disclosure. [Explanation of symbols]

[0150] 1 Work material 2 Grinding target part 3. 3D shape measuring device (example of shape measuring device) 4. Image processing device (an example of a detection device) 5 Robot motion control device (an example of a grinding tool control device) 6 Articulated robot (an example of a grinding device) 7. Grinder 8 Grindstone (an example of a grinding tool) 9 Grinding reaction force measuring device 10 Mobile cart (an example of a mobile mechanism) 11 Turning roller (an example of a moving mechanism) 12. Movement mechanism control device

Claims

1. A shape measuring device for measuring a three-dimensional shape and attitude of a workpiece; A detection device for detecting the position and shape of a portion to be ground that is present on the surface of the workpiece; a grinding device including a grinding tool for grinding the grinding target portion; a moving mechanism that moves the workpiece relative to the shape measuring device and the grinding device; a grinding tool control device that generates a trajectory of the grinding tool for grinding the portion to be ground based on the three-dimensional shape and orientation of the workpiece measured by the shape measuring device and the position and shape of the portion to be ground detected by the detection device, and controls the grinding tool so that the grinding tool moves along the trajectory; a movement mechanism control device that controls the movement mechanism so that the workpiece moves relative to the shape measuring device and the grinding device when the shape measuring device measures the workpiece and when the grinding target portion is ground by the grinding tool.

2. The grinding system according to claim 1 , wherein the workpiece is a circular material having a circular axial cross section.

3. The moving mechanism includes: a rotation mechanism that rotates the workpiece in a circumferential direction of the workpiece relative to the shape measuring device and the grinding device; The grinding system according to claim 1 or 2, further comprising a slide mechanism that moves the workpiece in an axial direction of the workpiece relative to the shape measuring device and the grinding device.

4. The grinding system according to claim 3 , wherein the movement mechanism control device relatively moves a circumferential position and an axial position of the workpiece based on a position and a shape of the portion to be ground.

5. When the size of the grinding target part is larger than the movable range of the grinding tool, the grinding tool control device generates a trajectory within the movable range and controls the grinding device so that the grinding tool moves along the trajectory; The grinding system according to claim 4 , wherein the movement mechanism control device determines the relative movement amounts of the circumferential and axial positions of the workpiece based on the size of the portion to be ground and the movable range of the grinding tool.

6. 2. The grinding system according to claim 1, wherein the movement mechanism control device determines the relative movement amounts of the circumferential and axial positions of the workpiece by prioritizing the grinding target portion having a larger size and excluding other grinding target portions that overlap with the grinding target portion having a larger size.

7. a shape measuring step of measuring a three-dimensional shape and attitude of the workpiece by a shape measuring device; a detection step of detecting a position and a shape of a portion to be ground that is present on a surface of the workpiece; a grinding process for generating a trajectory along which a grinding tool of a grinding device moves, based on the measured three-dimensional shape and attitude of the workpiece and the detected position and shape of the portion to be ground, and moving the grinding tool along the trajectory to grind the portion to be ground, The grinding method includes moving the workpiece relative to the shape measuring device and the grinding device in the shape measuring step and the grinding step.

8. A method for manufacturing an iron or steel product, comprising grinding a portion to be ground on a surface of the iron or steel product, which is the workpiece, by the grinding method according to claim 7.

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