Inspection method

Abstract

To provide an inspection method for detecting such abnormality that a flare nut is erroneously mounted by simple processing.SOLUTION: An inspection method for setting a tube with a flare nut including a screw part and a head part to be mounted on the outer periphery of a metal tube having an annular projection formed on its end in a normal direction at which the side of the screw part of the flare nut abuts on the annular projection as an inspection object includes: dividing image data obtained by imaging an imaging range including the flare nut into an outside area on the tip side and an inside area on an opposite side to the tip side; comparing a variation amount of a brightness value in the outside area with a variation amount of a brightness value in the inside area; and estimating whether or not the screw part exists on the side of the outside area on the basis of a magnitude relation of the variation amount, and thereby detecting such abnormality that the flare nut is mounted in a direction reverse to the normal direction.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] The present invention relates to an inspection method. [Background technology]

[0002] Automotive brake tubes are a widely known application of metal multi-wrapped tubes. Brake tubes are bent three-dimensionally to fit the shape of the vehicle's underfloor. To connect such tubes to various devices, annular protrusions are formed on both ends of the tube, and flare nuts are attached so that they abut against the annular protrusions. The tube is connected to various devices by inserting the end of the tube into the device and tightening the flare nuts. Such tube bending is generally performed with two matching flare nuts attached to both ends of the tube. For example, the device disclosed in Patent Document 1 below is known as an apparatus for bending metal tubes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3148663 Summary of the Invention [Problem to be solved by the invention]

[0004] The flare nut should be installed so that the threaded portion abuts against the annular protrusion, but if the flare nut is installed in the wrong direction, so that the head portion abuts against the annular protrusion, and the tube is bent, the product will be defective.

[0005] Therefore, one object of the present invention is to provide an inspection method that can detect an abnormality such as an incorrect installation of a flare nut using simple processing. [Means for solving the problem]

[0006] The inspection method of the present invention is a method for inspecting a tube with a flare nut, in which the flare nut, including a threaded portion and a head, should be attached to the outer periphery of a metal tube having an annular protrusion formed at its end, in the correct direction so that the threaded portion abuts the annular protrusion.The method divides image data obtained by capturing an image of an imaging range including the flare nut into an outside area at the tip and an inside area on the opposite side, compares the amount of variation in brightness value within the outside area with the amount of variation in brightness value within the inside area, and estimates whether the threaded portion is present on the outside area side based on the magnitude relationship of the amount of variation, thereby detecting an abnormality in which the flare nut has been attached in the opposite direction to the correct direction.

[0007] This inspection method divides the amount of variation in brightness values ​​in the image data into two areas, and by comparing the magnitude of the variation within each area, it is possible to estimate whether the threaded portion is on the tip side.Compared to processing that distinguishes between the threaded portion and the head by recognizing the shape and dimensional characteristics from image data, this method can detect abnormalities in the nut installation direction with simpler processing. [Effects of the Invention]

[0008] According to the present invention, an abnormality such as an incorrect installation of a flare nut can be detected by simple processing. [Brief explanation of the drawings]

[0009] [Figure 1A] FIG. 1 is a plan view showing the overall configuration of a tube bending system. [Figure 1B] FIG. 2 is a plan view showing an example of a tube to be processed. [Figure 2] FIG. 1B is a diagram showing a part of the system of FIG. 1A as viewed from the direction of arrow II. [Figure 3] FIG. 4 is a perspective view showing a part of the main configuration of the receiving section. [Figure 4] 4 is a view showing the receiving portion of FIG. 3 as viewed from the direction of arrow IV. [Figure 5] FIG. 10 is a side view illustrating the operation of the supply mechanism. [Figure 6]FIG. 10 is a perspective view showing a state in which the inspection mechanism inspects the tube to be processed. [Figure 7] FIG. 7 is a view showing the state as seen from the direction of arrow VII in FIG. 6. [Figure 8] FIG. 1 is a diagram showing the system configuration of an inspection mechanism. [Figure 9] FIG. 10 is a diagram showing an example of a method for detecting a tube supply abnormality. [Figure 10] 10A and 10B are diagrams showing another example of a method for detecting abnormal tube supply. [Figure 11] FIG. 10 is a diagram showing an example of a method for detecting an abnormality in the nut mounting direction. [Figure 12] An example of image data used for inspection. [Figure 13] 10 is a flowchart showing an example of processing of the tube bending system. DETAILED DESCRIPTION OF THE INVENTION

[0010] As an example, automotive brake tubes are made of metal and are used as piping to transmit the pressure generated in the master cylinder to the brake units installed on each wheel. The ends of the brake tubes are then processed for high pressure with a flare nut attached. Examples of high-pressure end processing include end processing that forms an annular protrusion, such as the ISO flare specified by the International Organization for Standardization (ISO) or the double flare specified by the Japan Automotive Engineering Society (JASO). The brake tubes undergo end processing to form an annular protrusion with a flare nut attached to the outer periphery, and three-dimensional bending to fit the shape of the vehicle's underfloor.

[0011] Figure 1A is a plan view showing the overall configuration of a tube bending system. The tube bending system (hereinafter referred to as the processing system) 1 includes a bending machine 2 that bends a tube to be processed Ta (see Figure 1B) into a predetermined shape, and a tube supply machine 3 that receives the tube to be processed Ta and supplies it to the bending machine 2. The processing system 1 can bend a variety of tubes to be processed Ta with different overall lengths. The tube to be processed Ta is fed into a tube input section 4 by an operator (not shown) for the tube supply machine 3. The tube Tb bent by the bending machine 2 is then collected in a collection section 5 provided in the bending machine 2.

[0012] As shown in FIG. 1B, the tube Ta is a straight metal tube T with annular protrusions Pr formed at both ends, with two flare nuts F attached to the outer periphery of the tube. Each flare nut F has a threaded portion Fa with a male thread and a head portion Fb adjacent to the threaded portion Fa where tightening torque is applied. In the illustrated example, the left and right flare nuts F have different axial dimensions. The tube Ta is covered with a resin coating layer C, which is stripped from each end to a predetermined range R1 or R2 to match the dimensions of the flare nut F to be attached. After the coating layer C is stripped, the end is processed to form the annular protrusions Pr with the flare nut F attached.

[0013] As shown in FIGS. 1A and 2 , the tube supplying machine 3 includes a aligning mechanism 10 that aligns the flare nuts F on the workpiece tube Ta, a conveying mechanism 11 that conveys the workpiece tube Ta to the bending machine 2 after the aligning operation, and an inspection mechanism 12 that uses the operation of the aligning mechanism 10 to detect any abnormalities in the workpiece tube Ta to be bent by the bending machine 2. The conveying mechanism 11 includes a hand 13 that grips the workpiece tube Ta after the aligning operation and inspection. The hand 13 is retractable relative to an arm 14 as shown by the arrow. The arm 14 is driven to rotate around a rotation center C by an electric motor E. The workpiece tube Ta for which no abnormalities are detected by the inspection mechanism 12 is delivered to the bending machine 2 by the conveying mechanism 11. On the other hand, the workpiece tube Ta for which an abnormality is detected is collected by the conveying mechanism 11 into a defective product box B, an example of a collection means, located within the operating range of the conveying mechanism 11.

[0014] As shown in FIG. 1B , the end-compressing operation by the end-compressing mechanism 10 involves moving two flare nuts F toward the end of the workpiece tube Ta so that one of the two flare nuts F abuts against one of the two annular protrusions Pr and the other of the two flare nuts F abuts against the other of the two annular protrusions Pr. Because the flare nuts F are not fixed to the tube and are axially movable, the end-compressing operation is performed for bending. As shown in FIGS. 1A and 2 , the end-compressing mechanism 10 includes a first set of a pair of receiving portions 15 arranged on the upper tier and a second set of a pair of receiving portions 15 arranged on the lower tier. The spacing between the pairs of receiving portions 15 on the upper and lower tiers can be set arbitrarily. For example, as shown in the illustrated example, by narrowing the spacing between the pair of receiving portions 15 on the upper tier and widening the spacing between the pair of receiving portions on the lower tier, two types of workpiece tube Ta, long and short, can be fed in and bent alternately. Each receiving section 15 is equipped with an inspection mechanism 12, which will be described in detail later. The edge-pushing mechanism 10 and receiving section 15 arranged in this manner have a symmetrical structure and are identical to each other. In the following description, they will not be distinguished from each other unless it is necessary to distinguish between them.

[0015] 3 and 4, the receiving unit 15 includes a tube receiving plate 16 that extends perpendicular to the axis Ax and is arranged so as to be movable in the direction of the axis Ax, and an actuator 17 that drives the tube receiving plate 16 in the direction of the axis Ax. An actuator 17 is also provided on the other receiving unit 15, and can drive the tube receiving plate 16 in the same direction. The tube receiving plate 16 corresponds to an example of a tube receiving member. Furthermore, the combination of two actuators 17, one provided on each of the pair of receiving units 15, corresponds to an example of a driving means according to the present invention.

[0016] The tube receiving plate 16 has a linear first inclined portion 18 that is inclined toward the bending machine 2 (to the right in FIG. 4 ) relative to the vertical direction, and a second inclined portion 19 that is perpendicular to the first inclined portion 18. A groove-like pocket 20 that receives a single tube Ta is formed in the second inclined portion 19. The width of the pocket 20 is slightly larger than the outer diameter of the tube Ta and smaller than the outer diameter of the flare nut F. Therefore, when the pair of tube receiving plates 16 are positioned on opposite sides of the annular protrusion Pr with the flare nut F sandwiched between them, when the tube receiving plates 16 move relative to each other in directions away from each other, the flare nut F is moved toward the end of the tube Ta, enabling an end-pushing operation. The pocket 20 corresponds to an example of a receiving groove.

[0017] 3 to 5, the processed tube Ta fed into the tube input section 4 (FIGS. 1A and 2) is fed into the receiving section 15 of the end gathering mechanism 10 via a feeding mechanism 25. The feeding mechanism 25 includes a belt conveyor 26 provided adjacent to the tube input section 4, and a feeding mechanism 27 that supplies the processed tube Ta transported by the belt conveyor 26 to the end gathering mechanism 10 one by one.

[0018] As shown in Figure 5, the supply mechanism 27 is arranged between the outlet portion 26a of the belt conveyor 26 and the receiving portion 15, and includes a slide member 28 which is a movable member that can move along the first inclined portion 18 of the tube receiving plate 16, and an actuator 29 that drives the slide member 28.

[0019] The slide member 28 includes a first portion 28a extending along the first inclined portion 18 and a second portion 28b extending perpendicularly from the first portion 28a, forming a generally horizontal T-shape overall. The second portion 28b is connected to a drive rod 29a of an actuator 29. The thickness of the first portion 28a is set to be equal to or smaller than the outer diameter of the workpiece tube Ta. As a result, as shown in FIGS. 5A and 5B , when the workpiece tube Ta is guided to the tip portion of the slide member 28, which is waiting at a position lower than the belt conveyor 26, and the slide member 28 moves along the first inclined portion 18, only one workpiece tube Ta is placed on the tip portion of the first portion 28a of the slide member 28 and lifted along the first inclined portion 18. The tip portion of the first portion 28a is inclined downward toward the first inclined portion 18. Therefore, a reaction force from the first portion 28a against gravity acting on the workpiece tube Ta acts on the side approaching the first inclined portion 18. Therefore, the workpiece tube Ta is less likely to separate from the first inclined portion 18, and the workpiece tube Ta is prevented from falling off during movement. Then, as shown in Fig. 5C, when the first portion 28a of the slide member 28 carrying the workpiece tube Ta reaches the upper end of the first inclined portion 18, the workpiece tube Ta rolls in the direction of the arrow on the second inclined portion 19 of the tube receiving plate 16 and enters the pocket 20.

[0020] 6 and 7, when the workpiece tube Ta enters the pocket 20, one of the end-collating mechanisms 10 moves the tube receiving plate 16 to the right in Fig. 7, and the other end-collating mechanism 10 on the opposite side (not shown) pulls the workpiece tube Ta in the opposite direction, thereby completing the end-collating operation. The receiving section 15 is provided with an inspection mechanism 12 that detects any abnormalities in the workpiece tube Ta.

[0021] The inspection mechanism 12 includes a stage 30 fixed to the frame 3a of the tube feeder 3, an arm 31 extending diagonally upward from the frame 3a, a bracket 32 ​​extending from the arm 31 in the direction of the axis Ax, and a digital camera 33 fixed to the bracket 32 ​​and facing the stage 30. The bracket 32 ​​includes a main body 32a fixed to the arm 31 and a camera mounting portion 32b fixed to the main body 32a. The digital camera 33 corresponds to an example of an imaging means. Because the stage 30 and the digital camera 33 are fixed to the common frame 3a, the positional relationship between the stage 30 and the digital camera 33 is fixed. The tube receiving plate 16 of the edge-collecting mechanism 10 is movable to a predetermined position on the stage 30. Therefore, when the edge-collecting operation by the edge-collecting mechanism 10 is completed, the tube Ta is positioned on the stage 30.

[0022] The digital camera 33 captures an image of an imaging range set to a range including the flare nut F of the workpiece tube Ta positioned on the stage 30, and outputs image data obtained by the imaging. An example of the output image data displayed on a display is shown in FIG.

[0023] As shown in Figure 8, the inspection mechanism 12 further includes a personal computer (PC) 35 provided for each digital camera 33 in order to process image data acquired by the digital cameras 33 and detect abnormalities in the workpiece tube Ta. A programmable logic computer (PLC) 36 is provided in the processing system 1 as a computer that controls various components, such as the bending machine 2, the tube supplying machine 3, the end-collecting mechanism 10, and the conveying mechanism 11. A touch panel 37 is connected to the PLC 36, and the PLC 36 accepts appropriate operations from an operator via the touch panel 37. Each PC 35 is connected to the PLC 36 by a communication cable 39 via a hub 38, and various types of information are exchanged between each PC 35 and the PLC 36 based on predetermined logic. This allows the inspection mechanism 12 to inspect the workpiece tube Ta in conjunction with the end-collecting operation performed by the end-collecting mechanism 10.

[0024] Here, we will explain the inspections performed by the inspection mechanism 12. The inspection mechanism 12 detects (1) a tube supply abnormality caused by the tube supply machine 3 receiving the processed tube Ta in the wrong left-right direction, and (2) an abnormality in the nut installation direction caused by an incorrect assembly in which the flare nut F is installed in the opposite direction to the annular protrusion Pr. Note that either (1) or (2) above may be performed.

[0025] (1) Tube supply abnormality detection There are two methods for detecting tube supply abnormalities: (a) Abnormality detection based on the peeling range of coating layer C As shown in Figure 1B, the peeling areas R1 and R2 of the workpiece tube Ta are different on the left and right sides. Therefore, by identifying the boundary position P1 between the peeling area R1 on one side and the non-peeling area R, and the boundary position P2 between the peeling area R2 on the other side and the non-peeling area R, it is possible to determine whether the tube supplying machine 3 received the workpiece tube Ta in the correct orientation or the reverse orientation. If it is determined that either boundary position P1 or P2 is different from the correct position, it is also determined that the other is different, so it is sufficient to identify either boundary position P1 or P2. Note that when there is no need to distinguish between boundary position P1 and boundary position P2, they will be referred to as boundary position P1 in the following explanation.

[0026] Based on the image data acquired by the digital camera 33, the PC 35 identifies the pixel number of the image data at which the boundary position P1 is located, and compares that pixel position with a correct pixel position acquired and stored in advance, and if there is a difference, detects a tube supply abnormality. As described above, the positional relationship between the digital camera 33 and the stage 30 is fixed, and the workpiece tube Ta is positioned relative to the stage 30 by the edge-aligning operation of the edge-aligning mechanism 10. Therefore, it is sufficient to compare the pixel position of the boundary position P1 with the correct pixel position without measuring the length of the peeling range R1.

[0027] The method by which the PC 35 identifies the pixel position of the boundary position P is as follows.

[0028] (a1) Grayscale the image data to remove the color elements. Then, store the brightness value for each pixel of the grayscaled image data. In this case, the brightness value is the pixel value of the grayscale image. Note that when using a color image, luminance is used as the brightness value.

[0029] (a2) As shown in FIG. 9, a rectangular area X1 is set on the tube Ta to be processed in the image data, and the area X1 is divided into two equal parts, left and right, to form areas X1a and X1b.

[0030] (a3) For each area X1a and X1b, the sum of the brightness values ​​of the pixels in that area is calculated. Then, the difference value D between the sum of area X1a and the sum of area X1b is calculated. If there is no boundary position P1 within area X1, there is almost no difference in the brightness values ​​of the image data between area X1a and area X1b. Therefore, the difference value D between the sums of areas X1a and X1b is close to 0.

[0031] (a4) While shifting the rectangular area X1 in the direction of the axis Ax along the tube to be processed, the difference value D is calculated according to (a3) ​​above. Then, the change in the difference value D becomes as shown in the graph in FIG.

[0032] (a5) Since the point where the center of area X1 is the boundary position P1 is the maximum value of the difference value D, the pixel position where the difference value D calculated in (a4) above is the maximum value is identified as the pixel position of boundary position P1.

[0033] (b) Anomaly detection based on the end position of the processed tube Ta The workpiece tube Ta is positioned relative to the stage 30 by the end-aligning operation of the end-aligning mechanism 10. Therefore, the end position P3 (see FIG. 10 ) of the workpiece tube Ta on the stage 30 is uniquely determined by the axial dimension of the attached flare nut F. If a flare nut F with a different axial dimension exists due to the erroneous feeding of the workpiece tube Ta in the opposite direction, the end position P3 on the stage 30 will differ from that in the case of normal feeding. Using this fact, the pixel position of the end position P3 in the image data is identified, and that pixel position is compared with the correct pixel position of the end position P3 previously acquired and stored. If there is a discrepancy, a tube feeding abnormality is detected. As with the abnormality detection described in (a) above, if one end position P3 differs from the correct position, it is determined that the other end position P3 also differs from the correct position. Therefore, it is sufficient to identify one end position P3 of the workpiece tube Ta.

[0034] The method by which the PC 35 identifies the pixel location of the terminal position P3 is as follows.

[0035] (b1) Grayscale the image data to remove the color components, and store the brightness value at each pixel of the grayscaled image data.

[0036] (b2) As shown in (i) of FIG. 10, the axis Ax is set as the x-axis, and the y-axis is set perpendicular to the x-axis. Then, the pixel brightness value p xy The sum sum in the y-axis direction x Calculate the sum sum x is expressed as Equation 1.

number

[0037] (b3) As shown in (ii) of FIG. 10, image data is smoothed in the x-axis direction. Specifically, the sum sum x Average the three pixels. x is expressed as Equation 2.

number

[0038] (b4) As shown in (iii) of Figure 10, the difference value D of the average value smoothx x Calculate the difference value D x is expressed as Equation 3.

number

[0039] (b5) As shown in (iv) of Figure 10, the difference value D x is greater than a predetermined threshold value th1 is identified as the pixel position corresponding to the terminal position P3 of the processed tube Ta.

[0040] (2) Detection of abnormal nut installation direction Abnormal nut installation direction is detected by identifying the threaded portion Fa of the flare nut F, which has uneven threads, based on the brightness information in the image data, and determining whether the side of the threaded portion Fa is on the tip side or the opposite side of the tube Ta. In other words, the image data is divided into an outside area on the tip side of the tube Ta and an inside area on the opposite side, and the amount of variation in brightness value within the outside area is compared with the amount of variation in brightness value within the inside area. Based on the magnitude relationship between these amounts of variation, it is estimated whether the threaded portion Fa is on the outside area side, thereby detecting abnormal nut installation direction. A specific example of this process is as follows.

[0041] (a) Grayscale the image data to remove the color components, and store the brightness value at each pixel of the grayscaled image data.

[0042] (b) As shown in (i) of Figure 11, an area X2 of size n x (a2 - a1) is set. Then, in area X2, the difference in brightness values ​​between adjacent pixels in the direction of axis Ax (x-axis direction) is calculated, and the absolute values ​​of these differences are all added together. This value represents the amount of variation in brightness within area X2. The greater the variation in brightness between adjacent pixels, the larger the numerical value of this variation. Variation amount diff x is expressed by Equation 4.

number

[0043] (c) As shown in (ii) of Figure 11, area X2 is shifted in the x-axis direction along the image of flare nut F, and the amount of variation diffx is calculated for each area X2 to obtain data that can be used to draw the graph in Figure 11.

[0044] (d) As shown in (iii) of Figure 11, the data obtained in (c) above is divided into two equal parts at the center in the x-axis direction, and the data at the tip of the division is designated as data belonging to the outside area Oa, and the data on the opposite side is designated as data belonging to the inside area Ia.

[0045] (e) For the variation amount diffx, a threshold value th2 that is greater than zero and smaller than the variation amount in the thread portion Fa is set in advance. Then, for the region less than the threshold value th2, the area Sa belonging to the outside area Oa is calculated, and the area Si belonging to the inside area Ia is calculated.

[0046] (f) The data for the variation amount diffx corresponding to the threaded portion Fa has a value greater than the threshold value th2. As a result, the area on the threaded portion Fa side is smaller. Therefore, by comparing the areas So and Si on both sides, if the area So of the outside area Oa where the threaded portion Fa should be is smaller than the area Si of the inside area Ia, it can be assumed that the installation direction of the flare nut F is correct. In other words, if the area So of the outside area Oa is larger than the area Si of the inside area Ia, it can be assumed that the threaded portion Fa is located on the inside area Ia side, and the flare nut F is detected as being installed in the wrong direction, indicating an abnormal nut installation direction.

[0047] In (d) above, the data obtained in (c) above was divided into two equal parts at the center in the x-axis direction to set the outside area Oa and the inside area Ia, but dividing the data region into two equal parts is merely an example. The allocation of the outside area Oa and the inside area Ia may be changed as appropriate depending on the dimensional ratio between the head Fb and the threaded portion Fa of the flare nut F assumed to be inspected.

[0048] In (e) and (f) above, a threshold value th2 is set, the area of ​​the region less than the threshold value th2 is calculated for each of the outside area Oa and the inside area Ia, and the magnitude of the brightness value fluctuation is compared. However, this is merely one example of a processing method based on the magnitude of the fluctuation. For example, without setting a threshold value th2, the presence of the thread portion Fa can be estimated by comparing the integral value of the fluctuation amount contained in the outside area Oa with the integral value of the fluctuation amount contained in the inside area. In this case, if the integral value of the outside area Oa is greater than the integral value of the inside area Ia, it is estimated that the installation direction of the flare nut F is correct. Conversely, if the integral value of the outside area Oa is smaller than the integral value of the inside area Ia, it is estimated that the installation direction of the flare nut is incorrect.

[0049] Next, the flow of processing executed by the PC 35 and the PLC 36 will be described with reference to Fig. 13. The routine in Fig. 13 includes a routine executed by the PLC 36 to control the operation of the bending machine 2 and the tube supply machine 3 of the processing system 1, and a routine executed by the PC 35 to control the operation of the inspection mechanism 12 and perform image processing and abnormality determination processing. These routines are executed in parallel by the PLC 36 and the PC.

[0050] In step S1, the PLC 36 sets the product number assigned to each product to be bent by the processing system. In step S2, the PLC 36 performs operation start setting and searches a database in which product information is associated with the product number to obtain information necessary for bending, such as a profile that specifies the bending shape.

[0051] In step S3, the PLC 36 controls the feeding mechanism 25 of the tube supplying machine 3 to move the workpiece tube Ta fed into the tube input section 4 to the receiving section 15 of the end gathering mechanism 10 (see FIGS. 3 to 5). Next, in step S4, the PLC 36 controls the end gathering mechanism 10 to perform an end gathering operation on the workpiece tube Ta fed into the receiving section 15. As a result, the workpiece tube Ta is positioned relative to the stage 30. Subsequently, in step S5, the PLC 36 controls the The provided inspection start flag F is set to ON.

[0052] In the other routine, in step S11, the PC 35 checks the content of the inspection start flag F and stores the content of the inspection start flag F. Then, it reads out information necessary for the inspection, such as pixel information on the peel boundary position and pixel information on the terminal position of the processed tube Ta corresponding to the set product number.

[0053] In step S12, if the inspection start flag F is ON, the PC 35 proceeds to step S13, and if the inspection start flag F is not ON, the PC 35 returns to step S11. In step S13, the PC 35 controls the digital camera 30 so that an image of the processed tube Ta positioned on the stage 30 is captured.

[0054] In step S14, the PC 35 processes the image data acquired by the digital camera 30 and executes an abnormality determination process to detect the above-mentioned tube supply abnormality and nut installation direction abnormality. Note that, in detecting tube supply abnormalities, both a method based on the boundary of the peeled layer of the processed tube Ta and a method based on the terminal position may be implemented, or either one may be implemented. If the PC 35 detects at least one of these abnormalities as a result of the abnormality determination process, it retains the determination result that there is an abnormality. If none of these abnormalities are detected, it retains the determination result that there is no abnormality. In step S15, the PC 35 transmits the retained information on whether there is an abnormality or no abnormality to the PLC 36 as the determination result.

[0055] In step S6, the PLC 36 refers to the information on the judgment result received from the PC 35, and if there is no abnormality, the process proceeds to step S7, and if there is an abnormality, the process proceeds to step S8. In step S7, the PLC 35 controls the conveying mechanism 11 (see FIG. 2) so that the inspected workpiece tube Ta is supplied to the bending machine 2, and also controls the bending machine 2 so that the workpiece tube Ta is bent by the bending machine 2.

[0056] Meanwhile, in step S8, the PLC 35 performs an abnormality detection process. As the abnormality detection process, the PLC 36 controls the conveying mechanism 11 so that the processed tube Ta in which an abnormality has been detected is collected into a defective product box B (see FIG. 2), and also displays a warning message on a display device such as a touch panel 37 (FIG. 8). Note that audio information such as a warning sound can be output instead of or together with the warning message.

[0057] The PC 35 functions as an example of an imaging control means by executing the processes of steps S11 to S13 in FIG. 13, and functions as an example of an abnormality detection means by executing the process of step S14 in FIG.

[0058] Although the embodiments to which the present invention is applied have been described above with reference to the drawings, the present invention is not limited to the above-described embodiments and can be embodied in various forms within the scope of the gist of the present invention.

[0059] Another form of end-alignment mechanism is, for example, a mechanism that has a downwardly inclined inclined member on which the tube to be processed can roll under its own weight, and a guide member that guides the tube to be processed onto the stage while moving the flare nut toward the end as the tube rolls on the inclined member, and that can guide the tube to the stage using these inclined member and guide member to position the tube to be processed on the stage.

[0060] The inventions that can be identified from the above embodiments and their modifications are disclosed below. Note that, to facilitate understanding of the disclosed inventions, the reference symbols and figure numbers used in the description of the above embodiments are written in parentheses, but the inventions are not limited to the shapes, structures, etc. of the components shown in the drawings.

[0061] The inspection method of the disclosed invention is an inspection method for inspecting a flare nut-attached tube (Ta), in which a flare nut (F) including a threaded portion (Fa) and a head (Fb) is to be attached to the outer periphery of a metal tube (T) having an annular protrusion (Pr) formed at its end, in the correct direction so that the threaded portion abuts the annular protrusion. The method divides the image data obtained by capturing an image of an imaging range including the flare nut into an outside area (Oa) on the tip side and an inside area (Ia) on the opposite side, compares the amount of variation in brightness value within the outside area with the amount of variation in brightness value within the inside area, and estimates whether the threaded portion is present on the outside area side based on the magnitude relationship between these amounts of variation, thereby detecting an abnormality in which the flare nut is attached in the opposite direction to the correct direction.

[0062] This inspection method divides the amount of variation in brightness values ​​in the image data into two areas, and by comparing the magnitude of the variation within each area, it is possible to estimate whether the threaded portion is on the tip side.Compared to processing that distinguishes between the threaded portion and the head by recognizing the shape and dimensional characteristics from image data, this method can detect abnormalities in the nut installation direction with simpler processing.

[0063] Furthermore, the following notes are disclosed: The tube bending system disclosed herein is a tube bending system that bends a workpiece tube into a predetermined shape, the workpiece tube including a metal tube having two annular protrusions formed at both ends and two flare nuts attached to the outer periphery of the metal tube, one of which corresponds to each of the two annular protrusions, and includes a bending machine that bends the workpiece tube, and a tube supply machine that receives the workpiece tube and supplies it to the bending machine. The tube supply machine has an end-pushing mechanism that performs an end-pushing operation to move the two flare nuts toward the end of the workpiece tube so that one of the two flare nuts abuts one of the two annular protrusions and the other of the two flare nuts abuts the other of the two annular protrusions, and an inspection mechanism that uses the end-pushing operation to detect abnormalities in the workpiece tube to be bent by the bending machine (Appendix 1).

[0064] This tube bending system detects abnormalities in the tube being processed by utilizing the edge-collapsing operation performed during the process from when the tube is received by the tube feeder to when it is bent by the bending machine. Because no physical operation dedicated to inspection of the tube being processed is required, it is possible to suppress the decrease in throughput that occurs when an inspection process is incorporated into the system. In addition, because abnormalities in the tube being processed can be detected before it is fed to the bending machine, it is possible to prevent the generation of defective products before the bending process.

[0065] In one aspect of the present disclosure, the inspection mechanism may include a stage on which the processed tube positioned by the edge-aligning operation is placed, an imaging means set on the stage that images an imaging range including the flare nut and outputs image data obtained, and has a fixed positional relationship with the stage, an imaging control means that controls the imaging means so that the imaging range is imaged while the processed tube is positioned on the stage, and an abnormality detection means that detects the abnormality in the processed tube based on the image data (Appendix 2).

[0066] According to this aspect, since the positional relationship between the stage and the imaging means is fixed, the imaging range set on the stage is constant. Therefore, abnormalities can be detected simply by comparing the positions of each part of the tube to be processed positioned on the stage with the normal positions of each part. There is no need to recognize the dimensions or outer shape of the tube to be inspected from image data.

[0067] The edge-pushing mechanism may have any appropriate configuration. For example, the edge-pushing mechanism may include a pair of left and right tube receiving members that are formed with a receiving groove having a width larger than the outer diameter of the tube to be processed and smaller than the outer diameter of the flare nut, the tube receiving members receiving the tube on the opposite side of the annular protrusion with the flare nut in between and are movable in the axial direction, and a drive means that can independently drive the pair of left and right tube receiving members, and the tube to be processed may be positioned with respect to the stage by moving one of the pair of left and right tube receiving members to a predetermined position on the stage and moving the other of the pair of left and right tube receiving members in a direction away from the stage (Appendix 3).

[0068] In one aspect of the present disclosure, the processed tube is prepared as an article to which different types of flare nuts having different axial dimensions are to be attached as the two flare nuts, and the abnormality detection means may detect, as the abnormality, a tube supply abnormality in which the tube supply machine receives the processed tube in an opposite left-right orientation (Appendix 4).

[0069] When flare nuts with different axial dimensions are attached to both ends of a tube to be processed, the tube can be distinguished as left or right. According to this embodiment, a tube to be processed that is fed in the wrong direction can be detected as a tube feeding error before bending. This prevents a defective tube from being produced due to incorrect feeding even though the tube is good. A good tube can be produced by re-feeding the tube with the tube feeding error in the correct direction.

[0070] In this aspect, the abnormality detection means may detect the tube supply abnormality by identifying the position of the end of the workpiece tube based on the image data (Appendix 5). Furthermore, if the surface of the workpiece tube is covered with a coating layer and the coating layer is peeled off from both ends by lengths that differ on the left and right sides depending on the axial dimensions of each of the two flare nuts, the abnormality detection means may detect the tube supply abnormality by identifying, based on the image data, the boundary position between the peeled area where the coating layer has been peeled and the non-peeled area where the coating layer has not been peeled (Appendix 6). Because the workpiece tube is positioned on the stage, these positions differ between normal and abnormal conditions. Therefore, tube supply abnormalities can be detected by identifying these positions.

[0071] In one aspect of the present disclosure, the abnormality detection means may detect, as the abnormality, an abnormality in the nut installation direction in which at least one of the two flare nuts abuts against the annular protrusion in a direction opposite to the normal direction (Supplementary Note 7). In this case, it is possible to prevent the occurrence of defective products in which a tube cannot be connected to a connection target.

[0072] In this aspect, each of the two flare nuts has a threaded portion on which a male thread is formed and a head portion adjacent to the threaded portion, and the abnormality detection means may detect an abnormality in the nut installation direction by dividing the image data including the image of the flare nut into an outside area on the tip side and an inside area on the opposite side, comparing the amount of variation in brightness value in the outside area with the amount of variation in brightness value in the inside area, and estimating whether the threaded portion is present on the outside area side based on the magnitude relationship between these amounts of variation (Appendix 8).

[0073] According to this aspect, by dividing the amount of variation in brightness values ​​in the image data into two areas and comparing the magnitude of the variation within each area, it is possible to estimate whether the threaded portion is on the tip side. Compared to processing that recognizes the shape and dimensional characteristics of the flare nut from image data to distinguish between the threaded portion and the head, this method makes it possible to detect abnormalities in the nut installation direction with simpler processing.

[0074] In one aspect of the present disclosure, the tube supplying machine further has a conveying mechanism that conveys the processed tube to the bending machine after the end-aligning operation, and if the inspection mechanism detects the abnormality, the conveying mechanism may convey the processed tube to a recovery means provided within the operating range of the conveying mechanism instead of conveying it to the bending machine (Appendix 9). [Explanation of symbols]

[0075] 1: Tube bending system 2: Bending machine 3: Tube supply machine 10: Edge alignment mechanism 11:Transport mechanism 12: Inspection mechanism 15: Reception Department 16: Tube receiving plate (tube receiving member) 17: Actuator (driving means) 20: Pocket (receiving groove) 30: Stage 33: Digital camera (imaging means) 35:PC B: Defective product box (recovery method) C: Covering layer F: Flare nut Fa:Threaded part Fb:Head P1, P2: Boundary position Pr: Annular protrusion R1, R2: Peeling range R: Non-peeling area T: Metal tube Ta: Tube to be processed

Claims

1. An inspection method for a flare nut-attached tube, in which a flare nut including a threaded portion and a head is to be attached to the outer periphery of a metal tube having an annular protrusion formed at the end thereof in a normal direction so that the threaded portion abuts against the annular protrusion, Image data obtained by capturing an image of an imaging range including the flare nut is divided into an outside area on the tip side and an inside area on the opposite side, comparing the amount of fluctuation in brightness value in the outside area with the amount of fluctuation in brightness value in the inside area; and detecting an abnormality in which the flare nut is attached in a direction opposite to the normal direction by estimating whether or not the threaded portion is present on the outside area side based on the magnitude relationship of the amount of variation. Testing method.

2. 2. The inspection method according to claim 1, wherein the areas of the regions relating to the amount of variation where the amount of variation is less than a threshold greater than zero are calculated for each of the outside area and the inside area, and whether or not the thread portion is present on the outside area side is estimated based on the relationship in size between the areas.

3. 3. The inspection method according to claim 1, wherein the abnormality is detected during a process of feeding the tube with the flare nut to a bending machine.

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