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] A widely known application of metal multi-wrapped tubes is the brake tubes of automobiles. The brake tubes are bent three-dimensionally to fit the shape of the underfloor of the vehicle. In order to connect such tubes to various devices, annular protrusions are formed on both ends of the tube, and flare nuts are attached so as to abut against the annular protrusions. The tube is connected to various devices by fastening the flare nut with the end of the tube inserted into the various devices. Such tube bending is generally performed with two flare nuts that fit both ends of the tube attached. For example, the device disclosed in Patent Document 1 below is known as a device 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 a tube with a flare nut installed in the wrong direction, so that the head portion abuts against the annular protrusion, is bent, the tube will be defective.

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

[0006] The inspection method of the present invention is an inspection method for 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 with the threaded portion abutting the annular protrusion, and image data obtained by imaging an imaging range including the flare nut is divided into an outside area at the tip side and an inside area on the opposite side, 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, and whether or not the threaded portion is present on the outside area side is estimated 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] According to this inspection method, the amount of variation in brightness value in the image data is divided into two areas, and by comparing the magnitude of the amount of variation within each area, it is possible to estimate whether the threaded portion is at the tip side. Compared to the process of recognizing the shape and dimensional characteristics of the threaded portion and the head from the image data, this method can detect abnormalities in the nut installation direction with simpler processing. Effect of the Invention

[0008] According to the present invention, an abnormality such as a flare nut being incorrectly attached can be detected by simple processing. [Brief description 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. [Diagram 2] FIG. 1B is a diagram showing a part of the system in FIG. 1A as viewed from the direction of arrow II. [Diagram 3] FIG. 4 is a perspective view showing a part of the main configuration of the receiving portion. [Figure 4] 4 is a view showing the receiving portion of FIG. 3 as viewed from the direction of arrow IV. [Diagram 5] FIG. [Figure 6]FIG. 4 is a perspective view showing a state in which the inspection mechanism inspects the processed tube. [Figure 7] FIG. 7 is a view showing a state as seen from the direction of arrow VII in FIG. 6. [Figure 8] FIG. 2 is a diagram showing the system configuration of an inspection mechanism. [Figure 9] 11A and 11B are diagrams 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 an abnormality in tube supply. [Figure 11] FIG. 13 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] 4 is a flowchart showing an example of a process of the tube bending system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] As an example, the brake tube of an automobile is a metal tube that is used as a pipe that transmits the pressure generated in the master cylinder to the brake unit installed on each wheel. The end of the brake tube is 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 an ISO flare specified by the International Organization for Standardization (ISO) or a double flare specified by the Japan Automotive Engineering Society (JASO). The brake tube is processed for end processing that forms an annular protrusion with a flare nut attached to the outer circumference, and is three-dimensionally bent to fit the shape of the underfloor of the automobile.

[0011] Fig. 1A is a plan view showing the overall configuration of a tube bending system. The tube bending system (hereinafter, abbreviated as the processing system) 1 includes a bending machine 2 that bends a tube to be processed Ta (see Fig. 1B) into a predetermined shape, and a tube supplying 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 plurality of types 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 supplying machine 3. Thereafter, the tube Tb bent by the bending machine 2 is collected in an accumulation 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 projections Pr formed at both ends, and two flare nuts F are attached to the outer periphery of the tube Ta so that they abut the annular projections Pr. The flare nut F has a threaded portion Fa with a male thread and a head portion Fb adjacent to the threaded portion Fa to which a tightening torque is input. In the illustrated example, the left and right flare nuts F have different axial dimensions. The tube Ta is covered with a coating layer C of a resin material, and the coating layer C is peeled off from each end to a predetermined range R1, R2 in accordance with the dimensions of the flare nut F to be attached. After the coating layer C is peeled off, the end processing is performed to form the annular projections Pr with the flare nut F attached.

[0013] As shown in FIG. 1A and FIG. 2, the tube supplying machine 3 has an end-collecting mechanism 10 that performs an end-collecting operation of a flare nut F on the tube Ta, a conveying mechanism 11 that conveys the tube Ta to the bending machine 2 after the end-collecting operation, and an inspection mechanism 12 that uses the operation of the end-collecting mechanism 10 to detect abnormalities in the tube Ta to be bent by the bending machine 2. The conveying mechanism 11 has a hand 13 that holds the tube Ta after the end-collecting operation and inspection. The hand 13 is provided so as to be freely 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 tube Ta for which no abnormality is detected by the inspection mechanism 12 is delivered to the bending machine 2 by the conveying mechanism 11. On the other hand, the tube Ta for which an abnormality is detected is collected by the conveying mechanism 11 into a defective product box B, which is an example of a collection means provided within the operating range of the conveying mechanism 11.

[0014] The end-commencing operation by the end-commencing mechanism 10 is an operation of moving two flare nuts F to the end side of the tube Ta to be processed 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, as shown in FIG. 1B. The flare nuts F are not fixed to the tube and are movable in the axial direction, so that the end-commencing operation is performed for bending. As shown in FIG. 1A and FIG. 2, the end-commencing mechanism 10 includes a first set in which a pair of receiving parts 15 is arranged in the upper stage, and a second set in which a pair of receiving parts 15 is arranged in the lower stage. The interval between the pair of receiving parts 15 provided in each of the upper stage and the lower stage can be set arbitrarily. For example, as shown in the example shown in the figure, by setting the interval between the pair of receiving parts 15 arranged in the upper stage to be narrow and the interval between the pair of receiving parts arranged in the lower stage to be wide, two types of tubes Ta to be processed, long and short, can be fed in and bent alternately. An inspection mechanism 12, which will be described in detail later, is installed in each receiving section 15. The edge pushing mechanism 10 and receiving section 15 thus arranged 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 them from each other.

[0015] 3 and 4, the receiving section 15 includes a tube receiving plate 16 that extends in a direction 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 in the other receiving section 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. Also, the combination of two actuators 17 provided on each of the pair of receiving sections 15 corresponds to an example of a driving means according to the present invention.

[0016] The tube receiving plate 16 has a first inclined portion 18 that is inclined toward the bending machine 2 (the right side in FIG. 4) in the vertical direction, and a second inclined portion 19 that is perpendicular to the first inclined portion 18. A groove-shaped pocket 20 that receives one 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 arranged on the opposite sides of the annular protrusion Pr with the flare nut F in between, and the tube receiving plates 16 move relatively in directions away from each other, the flare nuts F are moved toward the end of the tube Ta, enabling an end-pulling 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-collecting mechanism 10 via a feed mechanism 25. The feed mechanism 25 includes a belt conveyor 26 provided adjacent to the tube input section 4, and a supply mechanism 27 that supplies the processed tube Ta transported by the belt conveyor 26 to the end-collecting mechanism 10 one by one.

[0018] As shown in Figure 5, the supply mechanism 27 is disposed 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 movable along the first inclined portion 18 of the tube receiving plate 16, and an actuator 29 which 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, and is generally formed in a horizontal, generally T-shape. The second portion 28b is connected to a driving 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 tube Ta to be processed. As a result, as shown in A and B of FIG. 5, when the slide member 28 moves along the first inclined portion 18 in a state in which the tube Ta to be processed is guided to the tip portion of the slide member 28 waiting at a position lower than the belt conveyor 26, only one tube Ta to be processed 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 the gravity acting on the tube Ta acts on the side approaching the first inclined portion 18. Therefore, the tube Ta is less likely to separate from the first inclined portion 18, and the tube Ta is prevented from falling off during movement. Then, as shown in C of Fig. 5, when the first portion 28a of the slide member 28 carrying the tube Ta reaches the upper end of the first inclined portion 18, the tube Ta rolls on the second inclined portion 19 of the tube receiving plate 16 in the direction of the arrow and enters the pocket 20.

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

[0021] The inspection mechanism 12 includes a stage 30 fixed to the frame 3a of the tube supplying machine 3, an arm 31 extending obliquely 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 directed toward the stage 30. The bracket 32 ​​includes a main body 32a fixed to the arm 31 and a camera attachment part 32b fixed to the main body 32a. The digital camera 33 corresponds to an example of an imaging means. Since 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 end moving mechanism 10 can be moved to a predetermined position on the stage 30. Therefore, when the end moving operation by the end moving mechanism 10 is completed, the processed 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 imaging. An example of the output image data displayed on a display is shown in FIG.

[0023] As shown in Fig. 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 camera 33 and detect abnormalities in the tube Ta. A programmable logic computer (PLC) 36 is provided in the processing system 1 as a computer for controlling each part such as the bending machine 2, the end-collecting mechanism 10 of the tube supplying machine 3, and the conveying mechanism 11. A touch panel 37 is connected to the PLC 36, and the PLC 36 appropriately accepts 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 information is exchanged between each PC 35 and the PLC 36 based on a predetermined logic. This allows the inspection mechanism 12 to inspect the tube Ta in conjunction with the end-collecting operation performed by the end-collecting mechanism 10.

[0024] Here, the inspection performed by the inspection mechanism 12 will be described. The inspection mechanism 12 detects (1) a tube supply abnormality caused by erroneous supply in which the tube supplying machine 3 receives the processed tube Ta in the left-right reverse direction, and (2) a nut installation direction abnormality caused by erroneous assembly in which the flare nut F is installed in the opposite direction to the annular protrusion Pr from the normal direction. Note that the inspection mechanism 12 may perform either (1) or (2) above.

[0025] (1) Detection of tube supply abnormalities There are two methods for detecting tube supply abnormalities: (a) Detection of anomalies based on the extent of peeling of coating layer C As shown in Fig. 1B, the peeling ranges R1 and R2 of the tube Ta are different on the left and right. Therefore, by identifying the boundary position P1 between the peeling range R1 on one side and the non-peeling range R, and the boundary position P2 between the peeling range R2 on the other side and the non-peeling range R, it is possible to determine whether the tube supplying machine 3 received the tube Ta in the correct orientation or the reverse orientation. If it is known that the position of either the boundary position P1 or P2 is different from the correct position, it is also known that the other is different, so it is sufficient to identify the position of either the boundary position P1 or P2. Note that when it is not necessary to distinguish between the boundary position P1 and the boundary position P2, they will be represented as the boundary position P1 in the following explanation.

[0026] Based on the image data acquired by the digital camera 33, the PC 35 identifies which pixel of the image data the boundary position P1 is located at, and detects a tube supply abnormality if there is a difference between the pixel position and a correct pixel position acquired and stored in advance. As described above, the positional relationship between the digital camera 33 and the stage 30 is fixed, and the processed 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 location 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, X1b, the sum of the brightness values ​​of the pixels in that area is calculated. Then, a difference value D between the sum of areas X1a and X1b is calculated. If there is no boundary position P1 in area X1, there is almost no difference in the brightness value of the image data between areas X1a and 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, calculate the difference value D according to (a3) ​​above. Then, the change in the difference value D becomes as shown in the graph of FIG.

[0032] (a5) Since the point where the center of area X1 is boundary position P1 is the maximum value of difference value D, the pixel position where 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 tube to be processed Ta is positioned relative to the stage 30 by the end-compressing operation of the end-compressing mechanism 10. Therefore, the end position P3 (see FIG. 10) of the tube to be processed Ta on the stage 30 is uniquely determined by the axial dimension of the attached flare nut F. If there is a flare nut F with a different axial dimension due to erroneous feeding of the tube to be processed Ta in the opposite left and right directions, the end position P3 on the stage 30 will be different from that in the case of normal feeding. By utilizing this, the pixel number of the image data at which the end position P3 is located is identified, and the pixel position is compared with the correct pixel position of the end position P3 previously acquired and stored. If there is a difference, it is detected as a tube feeding abnormality. As with the abnormality detection in (a) above, if one end position P3 differs from the normal position, it is found that the other end position P3 also differs from the normal position, so it is sufficient to identify one end position P3 of the tube to be processed Ta.

[0034] The method by which PC35 identifies the pixel location of terminal position P3 is as follows.

[0035] (b1) Grayscale the image data to remove any 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 direction. Then, the pixel brightness value p xy The sum sum in the y-axis direction x Calculate the sum sum x is expressed by 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. The average value is smooth. x is expressed by Equation 2.

number

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

number

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

[0040] (2) Detection of abnormal nut installation direction The nut installation direction abnormality is detected by identifying the threaded portion Fa of the flare nut F, which has uneven threads, based on the light and dark information of the image data, and identifying whether the side of the threaded portion Fa is on the tip side or the opposite side of the tube Ta to be processed. In other words, the image data is divided into an outside area on the tip side of the tube Ta to be processed and an inside area on the opposite side, and the amount of variation in brightness value in the outside area is compared with the amount of variation in brightness value in the inside area, and 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 the nut installation direction abnormality. A specific example of this process is as follows.

[0041] (a) Grayscale the image data to remove any color components, and then 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 between adjacent pixels in the direction of axis Ax (x-axis direction) is taken, 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 will be. Variation amount diff x is expressed by Equation 4.

number

[0043] (c) As shown in (ii) of FIG. 11, the area X2 is shifted in the x-axis direction along the image of the flare nut F, and the amount of variation diffx is calculated for each area X2 to obtain data for plotting the graph of FIG. 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 amount of variation diffx, a threshold value th2 that is greater than zero and smaller than the amount of variation in the threaded portion Fa is preset. Then, for the region less than the threshold value th2, an area Sa belonging to the outside area Oa is calculated, and an area Si belonging to the inside area Ia is calculated.

[0046] (f) The data of the variation amount diffx corresponding to the threaded portion Fa has a value larger than the threshold value th2. Therefore, the area on the side of the threaded portion Fa becomes 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 presumed 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 is presumed that the threaded portion Fa is present on the inside area Ia side, and therefore the flare nut F is detected as being installed in the opposite direction, which is an abnormality in the nut installation direction.

[0047] In (d) above, the outside area Oa and the inside area Ia are set by dividing the data obtained in (c) in half at the center in the x-axis direction, but dividing the data region in half 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 the above (e) and (f), a threshold value th2 is set, and the area of ​​the area less than the threshold value th2 is calculated for each of the outside area Oa and the inside area Ia, and the magnitude relationship of the fluctuation amount of the brightness value is compared, but this is merely one example of a processing method based on the magnitude relationship of the fluctuation amount. For example, without setting the threshold value th2, the presence of the threaded 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 supplying 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 to 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 required for bending, such as a profile that specifies the bending shape.

[0051] In step S3, the PLC 36 controls the feed 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-collecting mechanism 10 (see Figs. 3 to 5). Next, in step S4, the PLC 36 controls the end-collecting mechanism 10 to perform an end-collecting operation on the workpiece tube Ta fed into the receiving section 15. As a result, the workpiece tube Ta is positioned with respect to the stage 30. Next, in step S5, the PLC 36 controls the feed mechanism 25 of the tube supplying machine 3 to control the start of inspection by the inspection mechanism 12. A 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, the PC 35 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 the process to step S11. In step S13, the PC 35 controls the digital camera 30 so that the tube Ta positioned on the stage 30 is imaged.

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

[0055] In step S6, the PLC 36 refers to the information on the judgment result received from the PC 35, and proceeds to step S7 if there is no abnormality, and proceeds to step S8 if there is an abnormality. 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] On the other hand, in step S8, the PLC 35 executes an abnormality detection process. As the abnormality detection process, the PLC 36 controls the transport 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 displays a warning display 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 display.

[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 embodiment to which the present invention is applied has been described above with reference to the drawings, the present invention is not limited to the above embodiment and can be embodied in various forms within the scope of the gist of the present invention.

[0059] As another form of end-alignment mechanism, for example, a mechanism that has a diagonally downward inclined member on which the tube to be processed can roll under its own weight, and a guide member that guides the flare nut to the stage while moving it toward the end of the tube to be processed rolling on the inclined member, and that can guide the tube to the stage using these inclined members and guide members to position the tube to be processed on the stage, can be used as the end-alignment mechanism.

[0060] The invention that can be specified from the above-mentioned embodiment and its modified examples will be disclosed below. Note that, in order to facilitate understanding of the disclosed invention, the reference symbols and figure numbers used in the description of the above-mentioned embodiment are written in parentheses, but the invention is not limited to the shapes, structures, etc. of the configurations shown in the drawings.

[0061] The inspection method of the disclosed invention is an inspection method for inspecting a tube with a flare nut (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 with the threaded portion abutting the annular protrusion, and the image data obtained by imaging an imaging range including the flare nut is divided into an outside area (Oa) on the tip side and an inside area (Ia) on the opposite side, the amount of variation in brightness value within the outside area and the amount of variation in brightness value within the inside area are compared, and based on the magnitude relationship between these amounts of variation, it is estimated whether the threaded portion is present on the outside area side, thereby detecting an abnormality in which the flare nut is attached in the opposite direction to the correct direction.

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

[0063] The following notes are further disclosed: The tube bending system disclosed herein is a tube bending system that bends a workpiece tube, which includes a metal tube having two annular protrusions formed at both ends and two flare nuts attached, one each to the outer periphery of the metal tube so as to correspond to each of the two annular protrusions, into a predetermined shape, and includes a bending machine that bends the workpiece tube, and a tube supplying machine that receives the workpiece tube and supplies it to the bending machine, wherein the tube supplying machine has an end moving mechanism that performs an end moving 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 moving 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 to be processed by utilizing the edge-collecting operation that is performed from when the tube is received by the tube supply machine until it is bent by the bending machine. Since no physical operation dedicated to inspection of the tube to be 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, since abnormalities in the tube to be processed can be detected before it is fed to the bending machine, it is possible to prevent the occurrence of defective products before bending.

[0065] In one aspect of the present disclosure, the inspection mechanism may include a stage on which the processed tube positioned by the edge pressing operation is placed, an imaging means set on the stage for outputting image data obtained by imaging an imaging range including the flare nut and having a fixed positional relationship with the stage, an imaging control means for controlling the imaging means so that the imaging range is imaged with the processed tube positioned on the stage, and an abnormality detection means for detecting the abnormality of 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, an abnormality can be detected simply by comparing the position of each part of the processed tube positioned on the stage with the normal position of each part. There is no need to recognize the dimensions or outer shape of the processed tube to be inspected from the image data.

[0067] The end-pushing mechanism may have an appropriate configuration. For example, the end-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, receive the tube to be processed on the opposite side of the annular protrusion with the flare nut in between, and are movable in the axial direction, and a driving means that is capable of independently driving the pair of left and right tube receiving members, and may position the tube to be processed 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 to be processed can be distinguished between left and right. According to this embodiment, a tube to be processed that is fed in the opposite left and right direction can be detected as a tube feed abnormality before bending. This can prevent a defective product from being produced due to erroneous feeding even though the tube to be processed is good. If the tube to be processed that has a tube feed abnormality is fed again in the correct direction, a good product can be produced.

[0070] In this aspect, the abnormality detection means may detect the tube supply abnormality by identifying the position of the end of the tube to be processed based on the image data (Appendix 5). In addition, when the surface of the tube to be processed 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 the boundary position between the peeled area where the coating layer has been peeled off and the non-peeled area where the coating layer has not been peeled off based on the image data (Appendix 6). Since the tube to be processed is positioned on the stage, these positions differ between normal and abnormal conditions. Therefore, by identifying these positions, it is possible to detect the tube supply abnormality.

[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 is abutted against the annular protrusion in a direction opposite to the normal direction (Appendix 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 formed with a male thread and a head 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 an 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 or not 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 value in the image data into two areas and comparing the magnitude relationship of the amount of variation within each area, it is possible to estimate whether the threaded portion is on the tip side. Compared to the process of recognizing the shape and dimensional characteristics of the flare nut from the image data in order to distinguish between the threaded portion and the head, an abnormality in the nut installation direction can be detected with a simpler process.

[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 when 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 rather than 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 (return 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. A method for inspecting a tube with a flare nut, in which a 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 an end thereof in a normal direction such that the threaded portion abuts against the annular protrusion, comprising: Image data obtained by imaging 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 a variation in brightness value in the outside area with a variation in brightness value in the inside area; and detecting an abnormality in which the flare nut is attached in a direction opposite to a 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, further comprising the steps of: calculating an area of ​​a region for which the amount of variation is less than a threshold value greater than zero for each of the outside area and the inside area; and estimating whether or not the threaded portion is present on the outside area side based on a 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 attached to it to a bending machine.

Images