JP2009222642A - Welding inspection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a welding inspection system for shortening the period required for inspection. <P>SOLUTION: The welding inspection system changes the direction of emission, and determines the propriety of the state of a nugget of a welding section based on the waveform of the level of reflected ultrasonic wave. A method of changing the emitting direction of the ultrasonic wave is divided into two stages of rocking operations. The one operation is a search rocking operation (S21-S24) of sequentially varying it in the small amount direction about a predetermined direction. Based on the level of the reflected wave detected during this operation, the direction close to the emitting direction suitable for the inspection is determined as a center emitting direction (S22). The other operation is a determination rocking operation (S26-S30) of sequentially varying it in the large amount direction about the center emitting direction. The search rocking operation is about the center emitting direction, so that the state of the nugget is determined rapidly. Therefore, the state of the nugget is appropriate, so that the period required for the inspection of the welding section is shortened. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a welding inspection system that inspects a welded portion of a member to be inspected.

  Conventionally, spot welding has been widely used in joining steel structures used in automobiles and the like. In this spot welding, as shown in FIG. 11, a nugget N is formed on the welded portion 43 (also referred to as “spot mark”) of the upper plate 41 and the lower plate 42 that are the members to be inspected W after the welding. The determination as to whether or not spot welding is appropriately performed is made based on whether or not the state of the nugget N is appropriate, for example. Recently, a method of using ultrasonic waves for inspection of the nugget N has been proposed. When performing an inspection using this ultrasonic wave, it is necessary to make the ultrasonic wave enter the welded portion 43 of the member W to be inspected perpendicularly. A method for automating this inspection has been proposed.

  For example, Japanese Patent Application Laid-Open No. 2006-153710 discloses a waveform of a level of a reflected wave from a welded portion 43 of a member W to be inspected (automatically swinging an inspection probe to change an emission direction of ultrasonic waves ( Hereinafter, a welding inspection system for determining whether or not the state of the nugget N of the welded portion 43 is appropriate based on “reflected wave level waveform”) is described.

JP 2006-153710 A

  By the way, in order to obtain a reflected wave level waveform for determining the state of the nugget N of the welded portion 43, it is necessary to align the central axis of the inspection probe with the normal direction of the welded portion 43. However, the welded portion 43 may be distorted due to wear of spot welding electrodes or impact during spot welding, and the normal direction of the welded portion 43 is not constant. Therefore, it is necessary to finely perform the swinging operation of the inspection probe in a wide range so that the central axis of the inspection probe is in the normal direction of the welded portion 43. If it does so, time required in order to test | inspect the one welding part 43 may become long.

  For example, in the above-described welding inspection system, the inspection probe is swung in 12 directions until the inspection probe is in an attitude that can obtain an optimum reflected wave level waveform (hereinafter referred to as “optimum attitude”). Takes up to 10 seconds or more. If the direction of swinging the inspection probe is reduced to shorten the time, the posture may not be optimal. In addition, when the speed of the swing operation of the inspection probe is increased, the processing speed of the signal input from the inspection probe cannot catch up, so only the reflected wave level waveform in an intermittent posture can be obtained, and the optimum reflected wave level The waveform may not be obtained.

  The present invention has been conceived under the circumstances described above, and an object thereof is to provide a welding inspection system capable of shortening the time required for inspection.

  In order to solve the above problems, the present invention takes the following technical means.

  The welding inspection system provided by the present invention emits ultrasonic waves to the welded portion of the member to be inspected, and inspects whether or not the state of the nugget formed in the welded portion is appropriate using the reflected wave. A welding inspection system, wherein the ultrasonic wave and its reflected wave are brought into and out of contact with the welded portion, and a plurality of preset emission directions of the ultrasonic wave centered on a predetermined direction. First control means for sequentially changing the direction of the ultrasonic wave from the welded portion of the ultrasonic wave detected by the probe means during a period in which the first control means is changing the emission direction of the ultrasonic wave. Based on the level of the reflected wave, the central emission direction determining means for determining the direction close to the ultrasonic emission direction suitable for the inspection as the central emission direction, and the ultrasonic emission direction is determined by the central emission direction determining means. Is Second control means for sequentially changing in a plurality of preset directions more than the direction of change by the first control means with the center emission direction as the center, and the second control means for the ultrasonic wave Whether or not the state of the nugget of the weld is appropriate based on the waveform of the level of the reflected wave from the weld of the ultrasonic wave detected by the probe means during the period of changing the emission direction Nugget state determination means for determining whether or not the nugget state determination means determines that the state of the nugget is appropriate.

  According to this configuration, a direction close to a direction suitable for inspection is determined as the center emission direction by the center emission direction determination means. Since the center emission direction is the center, the emission direction of the ultrasonic wave can be quickly directed to a direction suitable for inspection, and the state of the nugget can be determined quickly. Therefore, if the state of the nugget is appropriate, the time required for the inspection of the welded portion can be shortened. Since the emission direction of the ultrasonic wave changed by the first control unit is smaller than that by the second control unit, the time required for determining the central emission direction is short. Further, if the changing speed of the emission direction by the first control means is made faster than that by the second control means, the time required for determining the center emission direction can be further shortened. Therefore, the time required for the inspection according to the present configuration can be made shorter than when the emission direction is changed around the predetermined direction by the second control unit from the beginning.

  In a preferred embodiment of the present invention, the displacement means is attached to the probe means with an elastic member interposed therebetween and displaces the probe means in a direction orthogonal to the predetermined direction. A pressing unit that presses the probe unit substantially vertically with a predetermined pressing force;

  According to this configuration, the posture of the probe means is changed by being displaced by the displacement means while being pressed against the welded portion by the pressing means. Thereby, the emission direction of the ultrasonic wave is changed. Therefore, the first control means and the second control means can change the emission direction of the ultrasonic wave by displacing the probe means by the displacement means.

  In a preferred embodiment of the present invention, the displacement means and the pressing means are manipulators.

  According to this configuration, since the manipulator that moves the inspection probe to each welded portion also serves as the displacement means and the pressing means, it is not necessary to prepare a separate device as the displacement means and the pressing means, and the cost for that. Can be reduced. In addition, since the mounting of the inspection probe to the manipulator is simplified, the accuracy of positioning the inspection probe is improved. In addition, cable wiring that is a signal input / output path between the devices is reduced.

  In a preferred embodiment of the present invention, an angle formed by the center emission direction determined by the center emission direction determination means and the emission direction changed by the second control means is the predetermined direction and the first direction. It is smaller than the angle formed by the emission direction changed by the control means.

  According to this configuration, it is possible to reduce the time required for changing the emission direction by the second control unit. Therefore, the time required for the inspection of the welded portion can be further shortened.

  In a preferred embodiment of the present invention, the center emission direction determining means is configured such that when the first control means changes the emission direction of the ultrasonic waves and the level of the reflected wave becomes a predetermined level or more. The emission direction is determined as the central emission direction.

  According to this configuration, if the predetermined level is appropriately set, the center emission direction becomes a direction close to a direction suitable for inspection. Therefore, since the center emission direction is the center, the emission direction of the ultrasonic wave can be quickly directed in a direction suitable for inspection, and the state of the nugget can be determined quickly. Therefore, if the state of the nugget is appropriate, the time required for the inspection of the welded portion can be shortened.

  In a preferred embodiment of the present invention, the center emission direction determining means determines the emission direction when the level of the reflected wave is maximum as the center emission direction.

  According to this configuration, the center emission direction is closer to a direction suitable for inspection. Therefore, since the center emission direction is the center, the emission direction of the ultrasonic wave can be directed to a direction suitable for inspection earlier, and the state of the nugget can be determined earlier. Therefore, if the state of the nugget is appropriate, the time required for the inspection of the welded portion can be further shortened.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  1 and 2 are diagrams for explaining a first embodiment of a welding inspection system according to the present invention. FIG. 1 is a block diagram showing an overall configuration of the welding inspection system A1, and FIG. 2 is a diagram showing a configuration in the vicinity of the inspection probe 9. As shown in FIG. The welding inspection system A1 determines whether or not the spot welding is properly performed by inspecting the state of the nugget N of the welded portion 43 formed by spot welding.

  The welding inspection system A1 includes a manipulator 1, a robot control device 2, a swing control device 3, an inspection determination device 4, a CCD camera 5, an air cylinder 6, a horizontal swing device 7, an elastic member 8, and an inspection probe 9. ing. The welding inspection system A1 automatically moves the inspection probe 9 sequentially to each of the plurality of welds 43 (spot marks) formed on the member W to be measured, and automatically determines the quality of spot welding at each weld 43. Judgment can be made.

  The manipulator 1 moves the inspection probe 9 in the R direction of FIG. 1, for example, and sequentially conveys the inspection probe 9 to each welded portion 43 of the member W to be inspected. The manipulator 1 is a so-called six-axis robot, and is provided at a base member fixed to a floor or the like, six arms connected to the base member via six axes, and both ends or one end of the six arms. The motor is composed of six drive motors (servo motors) and an encoder provided in each drive motor (not shown).

  In the manipulator 1, six drive motors are driven to rotate by a drive signal from the robot control device 2, whereby each arm is displaced, thereby moving the inspection probe 9 to a predetermined position. The manipulator 1 moves the inspection probe 9 between the upper position of each welded portion 43 of the member to be inspected W and the standby position based on preset teaching data. Each encoder detects the rotational position of each drive motor and outputs a detection signal to the robot controller 2.

  The robot control device 2 is for controlling the operation of the manipulator 1 and the operation of the air cylinder 6 attached to the manipulator 1. The robot control device 2 recognizes the displacement state of each arm and the current position of the inspection probe 9 attached to the tip arm from the detection signal input from each encoder of the manipulator 1.

  The robot control device 2 drives and controls each drive motor of the manipulator 1 based on the recognized current position of the inspection probe 9 and a work program stored in advance in a memory (not shown). That is, the memory of the robot control device 2 stores teaching data representing the operation locus of the manipulator 1 together with the work program in advance, and the robot control device 2 inspects the spot welding of the welded portion 43 of the member W to be inspected. When the start is instructed, the manipulator 1 is operated at a predetermined timing based on the teaching data. Further, the robot control device 2 controls driving of the air cylinder 6. Further, the robot control device 2 instructs the swing control device 3 to start a swing operation, and instructs the inspection determination device 4 to start the quality determination of spot welding of the welded portion 43.

  A CCD camera 5 is attached to the arm 11 at the tip of the manipulator 1 by using a substantially V-shaped bracket 12 in a sectional view. The CCD camera 5 accurately matches the position of the central axis M (corresponding to the central axis of the ultrasonic wave emitted from the inspection probe 9) in the longitudinal direction of the inspection probe 9 to the center position of each welded portion 43 of the member W to be inspected. It is used for this purpose.

  The CCD camera 5 is connected to the swing control device 3. The swing control device 3 performs predetermined processing on the image signal picked up by the CCD camera 5 and pattern-matches the welded portion 43 (spot mark) of the member W to be inspected based on the obtained image data. Detect by the method. The swing control device 3 determines that the center axis M of the inspection probe 9 is in the vicinity of the center position of the spot mark when the spot mark comes to the approximate center position of the imaging screen, and determines the determination result. Transmit to the robot controller 2. The robot control device 2 stops the inspection probe 9 at a position above the center position of the welded portion 43 by stopping the manipulator 1 based on the signal.

  An air cylinder 6 is attached to the lower part of the main body 12 a of the bracket 12. The air cylinder 6 functions as a pressing mechanism that presses the inspection probe 9 against the member W to be inspected, and is extendable in the vertical direction in FIG. The air cylinder 6 is driven by a drive signal from the robot controller 2 and is displaced from the normally contracted state to the extended state, and presses the tip of the inspection probe 9 against the member W to be inspected with a predetermined pressing force.

  After stopping the movement of the inspection probe 9 by the manipulator 1, the robot control device 2 outputs a drive signal to the air cylinder 6 and operates the air cylinder 6 so as to press the tip of the inspection probe 9 against the member W to be inspected. Let The distance by which the inspection probe 9 moves up and down by the air cylinder 6 is determined in advance so that the inspection probe 9 is not damaged even if it contacts the member to be inspected W when the air cylinder 6 is extended. The stop position of the air cylinder 6, that is, the stop position when the air cylinder 6 is displaced from the retracted state to the extended state and the stop position when the air cylinder 6 is displaced from the extended state to the retracted state are set by a proximity switch or the like (not shown). It may be.

  A horizontal rocking device 7 is provided below the air cylinder 6. The horizontal rocking device 7 is for displacing the inspection probe 9 in a direction orthogonal to the central axis M. The horizontal oscillating device 7 includes two oscillating devices, and an X direction oscillating device 71 for displacing the inspection probe 9 in a predetermined direction (this direction is referred to as “X direction”) and a direction orthogonal to the X direction. It comprises a Y-direction swinging device 72 that displaces the inspection probe 9 in this direction (referred to as “Y-direction”).

  Each of the X-direction oscillating device 71 and the Y-direction oscillating device 72 has a motor (not shown), and each motor is independently driven by a drive signal from the oscillating driving device 10. When the tip of the inspection probe 9 is not pressed against the member W to be inspected, the horizontal swing device 7 displaces the position of the central axis M of the inspection probe 9 in the X direction, the Y direction, or an oblique direction that combines both directions. This displacement control is used for fine adjustment when the position of the center axis M is accurately aligned with the center position of the welded portion 43.

  Further, when the tip of the inspection probe 9 is pressed against the member W to be inspected, the tip of the inspection probe 9 is fixed at the center position of the welded portion 43. Only the portion (the end fixed to the elastic member 8 of the inspection probe 9) is displaced in the X direction, the Y direction, or an oblique direction that combines both directions. With this displacement, the inclination of the central axis M of the inspection probe 9 changes in the X direction, the Y direction, or an oblique direction that combines both directions. This displacement control is used for a swing operation for searching for an optimum posture by changing the inclination of the central axis M. The control of the swing operation of the inspection probe 9 will be described later.

  The swing drive device 10 includes a control unit 101, an X direction drive unit 102 that drives the X direction swing device 71, and a Y direction drive unit 103 that drives the Y direction swing device 72. When the control signal is input from the swing control device 3, the control unit 101 operates the X direction swing device 71 and the Y direction swing device 72 by the X direction drive unit 102 and the Y direction drive unit 103.

  As shown in FIG. 2, a moving plate 73 is provided below the horizontal swing device 7. The moving plate 73 is connected to the Y-direction swinging device 72 and is displaced in the X direction, the Y direction, and a direction in which those directions are combined.

  An elastic member 8 made of a substantially rectangular parallelepiped resin is attached to the lower surface of the moving plate 73. The elastic member 8 is elastically deformable and is interposed between the horizontal swing device 7 and the inspection probe 9. Therefore, when the horizontal swing device 7 displaces the moving plate 73 in the XY plane with the tip of the inspection probe 9 pressed against the member W to be inspected, the elastic member 8 reduces the displacement amount of the moving plate 73 by one. This is absorbed and transmitted to the base end of the inspection probe 9. Accordingly, only the base end portion of the inspection probe 9 is slightly displaced in the horizontal plane, and the central axis M of the inspection probe 9 is inclined by a small angle with respect to the normal direction n of the member W to be inspected at the center position of the welded portion 43. To achieve the operation.

  The shape of the elastic member 8 is not limited to a substantially rectangular parallelepiped shape, and may be a substantially cylindrical shape, a substantially triangular prism shape, or the like. For example, a resin such as rubber is suitable as the elastic member 8. However, the elastic member 8 is not limited to a resin as long as it is an elastic member that can realize the swing operation of the inspection probe 9. For example, phosphor bronze or the like. It is also possible to use a plate material or spring material made of a metal having the above elastic properties. In short, since the elastic member 8 functions as a cushioning material when the displacement force of the horizontal oscillating device 7 is transmitted to the inspection probe 9, the elastic member 8 has an elastic deformation characteristic capable of appropriately oscillating the inspection probe 9. As long as it is, the material is not particularly limited.

  An inspection probe 9 is provided below the elastic member 8. The inspection probe 9 includes an elastically deformable probe holder 91 attached to the lower part of the elastic member 8 and a substantially cylindrical main body 92. The probe holder 91 is provided with a recess (not shown), and the upper portion of the main body 92 is accommodated in the recess. The elastic member 8 and the probe holder 91 may be formed integrally.

  The inspection probe 9 includes a water chamber type flexible membrane probe. That is, the inspection probe 9 is filled with water in a main body 92 in which an opening for emitting ultrasonic waves and incident reflected waves is formed at the tip (lower end in FIG. 2), and the opening is a thin film made of silicon rubber. It is configured with a plug. The silicon rubber bulges from the opening into a substantially hemispherical shape due to water pressure, and this bulge portion serves as a contact portion 93 that makes the inspection probe 9 contact the welded portion 43 of the member W to be inspected.

  A transmitter (not shown) for emitting ultrasonic waves is provided inside the main body 92 near the other end surface (upper surface). When the transmitting part emits ultrasonic waves toward the contact part 93, the ultrasonic waves are emitted to the welded part 43 of the member W to be inspected through the contact part 93. Further, the ultrasonic wave (hereinafter referred to as echo) reflected in the welded portion 43 is incident on the main body 92 via the contact portion 93 and received by a receiving portion (not shown) in the main body 92. Since the contact portion 93 is filled with water, the contact surface changes flexibly according to the shape of the welded portion 43, and can come into contact with the welded portion 43 stably with an extremely high degree of adhesion. Further, since the main body 92 and the contact portion 93 are filled with water, the ultrasonic waves and their echoes are propagated between the welded portion 43 with high efficiency and the sensitivity reduction is suppressed as much as possible. Yes.

  Returning to FIG. 1, the inspection determination device 4 is connected to the inspection probe 9. The inspection determination device 4 is composed of, for example, a notebook personal computer, converts an electrical signal (analog signal) obtained by detecting an echo input from the inspection probe 9 into a digital signal, and the state of the nugget N is based on this signal. A pass / fail judgment is performed. The quality determination procedure is incorporated in a dedicated software program stored in a memory (not shown) in the inspection determination device 4. The inspection determination device 4 includes a monitor (not shown), and a waveform representing an echo detection signal transmitted from the inspection probe 9 is displayed on the monitor in real time.

  FIG. 3 is an example of a waveform displayed on the monitor screen of the inspection determination device 4. The horizontal axis of the monitor screen indicates time, and the vertical axis of the monitor screen indicates the peak value (echo level) of the waveform. When the nugget state (hereinafter referred to as “nugget state”) is normal, a plurality of peaks are shown in the waveform at a predetermined time interval D based on the plate thickness of the upper plate 41 and the lower plate 42 as shown in FIG. Is repeatedly detected, and the attenuation curve C connecting the peak values of these peaks outputs a waveform pattern that draws a predetermined attenuation curve.

  The inspection determination device 4 performs pass / fail determination of the nugget state based on an echo level waveform (hereinafter referred to as an “echo waveform”). The nugget pass / fail judgment is performed by evaluating the number of detected peaks, the peak value H of each peak, the time interval D between each peak, the presence or absence of a peak that does not originally appear, and the like. The condition for determining whether the nugget state is good may be obtained from data obtained by inspecting a plurality of good nugget states in a sample manner.

  The quality determination of the nugget state based on the echo waveform should be performed in a state (optimal posture) in which the inspection probe 9 is pressed against the welded portion 43 of the member W to be inspected in an appropriate direction. Therefore, when searching for the optimal pressing direction by swinging the inspection probe 9 as in the present embodiment, it is determined whether the nugget state is good or not after setting the inspection probe 9 in the optimal direction by the search. Basic.

  However, whether or not the pressing direction of the inspection probe 9 against the welded portion 43 is appropriate is performed while observing the echo waveform displayed on the monitor screen, as in the case of the nugget state determination. In this embodiment, if the base end portion of the inspection probe 9 is displaced and an echo waveform that is determined to be normal is output at any displacement position, the nugget state is determined to be normal at that time, and the inspection probe 9 The search for the pressing direction to the welded portion 43 ends. If no echo waveform that is determined to be normal is output at any displacement position, the nugget state is determined to be defective.

  That is, the process of searching for the optimum pressing direction of the inspection probe 9 against the welded portion 43 searches for whether or not a substantially normal echo waveform can be obtained. It is also. Therefore, when the pressing direction in which the nugget state is determined to be normal is found during the process of searching for the optimal pressing direction of the inspection probe 9 to the welded portion 43, the inspection determination device 4 immediately performs the search operation. It has a function to stop (hereinafter, this function is referred to as “auto freeze function”). In the welding inspection system according to the present embodiment, the processing time for determining the quality of each welded portion 43 of the member W to be inspected is shortened as much as possible by this auto freeze function.

  When the inspection determination device 4 changes the pressing direction of the inspection probe 9 against the welded portion 43 of the member W to be inspected while determining the echo waveform, if a normal echo waveform is found, the automatic freeze function immediately The determination process is stopped, and an auto freeze signal indicating that the determination process is completed is transmitted to the robot controller 2. When the robot control device 2 receives this auto freeze signal, it transmits a control signal for stopping the operation of the horizontal swing device 7 to the swing control device 3, and the swing control device 3 receives this control signal. The operation of the horizontal swing device 7 is stopped.

  The inspection determination device 4 also outputs a digitized echo detection signal input from the inspection probe 9 to the swing control device 3.

  The swing control device 3 is composed of, for example, a personal computer, and performs spot mark position detection processing based on an operation program stored in a memory (not shown) and an image signal captured by the CCD camera 5. Further, the swing control device 3 drives and controls the swing drive device 10 based on a control signal from the robot control device 2 to operate the horizontal swing device 7 and swing the inspection probe 9.

  In the present embodiment, before the swing operation for determining whether the nugget state is good (hereinafter referred to as “determination swing operation”), the swing operation for determining the center of the determination swing operation (hereinafter referred to as “determination swing operation”). It is characterized in that it is called “search swing motion”. In the search swing operation, a rough swing operation is performed relatively quickly in a wide range. The swing control device 3 determines the inclination of the central axis M of the inspection probe 9 when the echo level exceeds a predetermined value in the search swing operation as the center of the next determination swing operation, and performs the search swing. Stop operation. In the determination swing operation, a fine swing operation is performed relatively slowly in a narrow range around the inclination of the central axis M determined in the search swing operation.

  Hereinafter, the search swing operation by the swing control device 3 will be described.

  The swing control device 3 controls the drive of the swing drive device 10 and displaces the base end portion of the inspection probe 9 in a plurality of directions by the horizontal swing device 7. As a result, the pressing direction of the inspection probe 9 against the welded portion 43 changes around the normal direction n of the member W to be inspected. FIG. 4 is a diagram for explaining the displacement of the base end portion of the inspection probe 9 and the inclination of the central axis M of the inspection probe 9 in the search swinging operation.

  As shown in FIG. 4A, the horizontal oscillating device 7 displaces the center of the base end portion of the inspection probe 9 in the XY plane in a trajectory that draws a plurality of arcs while passing through the center position P0. FIG. 4A is a view of the inspection probe 9 as viewed from above, and the center position P0 coincides with the origin of the XY coordinates. The trajectory is composed of an arc portion and a linear portion indicating the diameter or radius of a circle (see dotted line S) assumed in the arc, and these are continuously connected.

  The radius L (for example, 2 mm) of the circle S and the division number D (for example, 4) of the circle S are set and input in advance in the swing control device 3. The radius L of the circle S and the division number D of the circle S can be set and changed in the swing control device 3, and are not limited to the above values. If the radius L and the number of divisions D are reduced, the trajectory is shortened, so the time required for rocking is shortened, but the search range is narrow and rough. On the other hand, when the radius L and the number of divisions D are increased, the search range becomes wider and narrower, but the trajectory becomes longer, so the time required for rocking becomes longer. The search rocking motion is intended to perform a rough rocking motion over a wide range. Therefore, it is desirable that the radius L is set to a length capable of searching the necessary range, and the division number D is made as small as possible. Note that the swinging trajectory of the inspection probe 9 is not limited to the above-described trajectory, and may be a trajectory that travels in a spiral shape toward the center position P0.

  The swing control device 3 transmits a drive signal to the swing drive device 10 so that the center of the base end portion of the inspection probe 9 moves along the trajectory shown in FIG. The swing drive device 10 operates the X-direction swing device 71 and the Y-direction swing device 72 that are the horizontal swing device 7 based on the drive signal. The moving plate 73 is displaced by the movement operation of the two swinging devices 71 and 72 in each direction, and thereby the base end portion of the inspection probe 9 is displaced.

  More specifically, assuming that the upward direction in FIG. 5A is the Y direction, the horizontal rocking device 7 is separated from the center position P0 by the distance L from the center position P0 in the Y direction. Move to position P1 (see a). Next, it is moved so as to return once from the position P1 to the center position P0 (see b), and is moved from the center position P0 to a position P2 away from the position P1 by a distance L (see c). The movement from the position P1 to the center position P0 and the movement from the center position P0 to the position P2 may be performed continuously.

  Next, the center of the base end portion of the inspection probe 9 is placed on the circumference of the circle S from the position P2 to the position P3 where the angle α formed by the center position P0 is 90 degrees while keeping the radius L from the center position P0 constant. Move along (see d). Thereafter, after moving from the position P3 to the position P4 through the diameter of the circle S, the center of the base end portion of the inspection probe 9 is moved so as to finally return to the center position P0.

  When the horizontal oscillating device 7 moves the center of the base end of the inspection probe 9 from the position P1 to the position P2 (see b and c) and from the position P3 to the position P4, the moving speed is kept at V1. Be drunk. This is to properly perform the process of monitoring the echo level performed to determine the center of the determination swing operation. Since the search swing operation is not for searching for an optimal echo waveform in the examination determination device 4, the moving speed v can be set to a relatively high speed. In the present embodiment, 4 mm / sec, which is twice the moving speed v ′ during the determination swing operation described later, is set. However, it is set as appropriate depending on the material of the member W to be inspected and the nugget diameter. Note that when moving from the center position P0 to the position P1 (see a), when moving from the position P2 to the position P3 (see d), and when moving from the position P4 to the center position P0, the purpose is to move. There is no limit to the speed of movement.

  FIG. 5 is a diagram for explaining the inclination of the central axis M of the inspection probe 9. As shown in the figure, the moving plate 73 is moved by the horizontal oscillating device 7 in the XY plane while the horizontal oscillating device 7 and the inspection probe 9 are pressed against the member W to be inspected by the air cylinder 6 with a predetermined pressing force P. When the inside is displaced, a force (hereinafter referred to as “combined force”) obtained by combining the pressing force P by the air cylinder 6 and the displacement force Q by the horizontal swing device 7 is transmitted to the inspection probe 9 through the elastic member 8. Is done.

  Since the contact portion 93 of the inspection probe 9 is pressed against the welded portion 43 of the member W to be inspected by the pressing force P by the air cylinder 6, it does not move even when the combined force is applied. Therefore, as shown in the figure, the central axis M is covered by the contact portion 93 (the central position O of the welded portion 43 in the figure) by a component parallel to the displacement force Q of the combined force acting on the base end portion. The inspection member W is tilted at a small angle β with respect to the normal direction n of the inspection member W.

  Then, since the horizontal oscillating device 7 displaces the center of the base end portion of the inspection probe 9 along the track shown in FIG. 4A, the central axis M is shown in FIG. 4B with the contact portion 93 as a fulcrum. Thus, after tilting in the Y-axis direction by a small angle β in the + direction (upper left direction in the same figure (b)) and-direction (lower right direction in the same figure (b)), it is 90 ° counterclockwise. By changing the tilt direction, the X-axis direction is tilted by a small angle β in the + direction (upper right direction in FIG. 5B) and the − direction (lower left direction in FIG. 5B).

  The swing control device 3 monitors an echo detection signal input from the examination determination device 4 while the search swing operation is performed. When the center axis M of the inspection probe 9 coincides with the normal direction of the weld 43, which is the optimum pressing direction against the weld 43, the echo level becomes maximum, but the normal direction of the weld 43 If the angle deviates by 1 degree or more, the echo detection signal hardly appears. In the present embodiment, when the echo level exceeds a predetermined value, it is determined that the central axis M has approached the normal direction of the weld 43, and the search swing operation is stopped. Then, the determination swing operation is performed around the inclination of the central axis M at this time.

  The determination swing operation is controlled in the same manner as the search swing operation, but the operation distance L ′ from the swing center, the number of divisions D ′ in the swing direction, and the moving speed v ′ are different. Since the determination swing operation is performed when the center axis M approaches the normal direction of the weld 43, the operation distance L 'can be reduced. In the present embodiment, the operating distance L ′ is set to, for example, ¼ of the operating distance L in the search swing operation, but is appropriately set depending on the material of the member W to be inspected, the nugget diameter, and the like. On the other hand, in the determination swing operation, it is necessary to align the center axis M with the normal direction of the welded portion 43. Therefore, it is necessary to increase the number of divisions D 'in the swing direction and perform a fine swing operation. In the present embodiment, for example, twelve, but it is necessary to appropriately set the number of divisions so that the minimum number of divisions is obtained in a range where the determination of the inspection is reliably performed. Further, since the determination swing operation is for searching for an optimal echo waveform in the inspection determination device 4, it is necessary to match the processing speed of the signal input from the inspection probe 9. Therefore, in the present embodiment, the moving speed v ′ is set to 2 mm / sec. However, the moving speed v ′ is appropriately set depending on the processing capability of the inspection determination device 4.

  FIG. 6 is a diagram for explaining the displacement of the base end portion of the inspection probe 9 in the determination swing operation.

  The center position P0 'is the center position of the base end portion of the inspection probe 9 when the search swing operation is stopped. In the determination swing operation, the division number D ′ in the swing direction is set to 12, so the horizontal swing device 7 moves the base end portion of the inspection probe 9 in the direction from the center position P 0 ′ to 12. The movement control is the same as in the case of the search swinging operation. According to the arrow shown in the figure, the movement is sequentially performed from the center position P0 'to the position P12', and finally moved back to the center position P0 '.

  When the horizontal oscillating device 7 moves the center of the base end portion of the inspection probe 9 from the position P0 ′ to the position P1 ′ (see a ′), and moves it from the position P12 ′ to the center position P0 ′, the circle S ′ When moving along the circumference, there is no limit on the moving speed because it is intended to move. However, when moving on the diameter of the other circle S ′, the moving speed v ′ is applied.

  Next, the inspection procedure in the above configuration will be described with reference to the flowcharts shown in FIGS. FIG. 7 is a flowchart for explaining an inspection procedure, and FIG. 8 is a flowchart for explaining a swing operation process performed by the swing control device.

  First, when the inspection is started, the manipulator 1 is driven by the robot controller 2, and the inspection probe 9 is moved based on the teaching data so as to scan on the member W to be inspected (S1). During this movement, the surface of the member W to be inspected is imaged by the CCD camera 5 (S 2), and the imaging signal imaged by the CCD camera 5 is sent to the swing control device 3.

  In the swing control device 3, the image pickup signal sent from the CCD camera 5 is converted into a digital signal, and an image is analyzed based on the converted signal to determine whether or not a spot mark formed on the member W to be inspected is detected. (S3). When a spot mark is detected in the swing control device 3 (S3: YES), the image analysis operation is temporarily stopped in the swing control device 3 (S4), and the swing control device 3 applies to the robot control device 2. A signal indicating that a spot mark has been detected is sent.

  In the robot control device 2, when a signal indicating that a spot mark has been detected is sent from the swing control device 3, the operation based on the teaching data of the manipulator 1 is stopped (S <b> 5). A signal indicating that the manipulator 1 has been stopped is sent.

  Thereby, in the swing control device 3, the image captured by the CCD camera 5 is re-taken (S6), the luminance gravity center position (center position O) of the spot mark is calculated (S7), and the center of the inspection probe 9 is calculated. A control signal is output to the swing drive device 10 so as to move the axis M to the center position P0.

  The swing drive device 10 drives the horizontal swing device 7 based on a control signal from the swing control device 3 and moves the inspection probe 9 so that the center axis M of the inspection probe 9 coincides with the center position P0. (S8).

  Next, the swing control device 3 sends a signal to the robot control device 2 to lower the air cylinder 6. When the robot control device 2 receives this signal, it sends a drive signal to the air cylinder 6 to extend it, and the air cylinder 6 is extended in response to this drive signal (S9). As a result, the inspection probe 9 is lowered downward, and the contact portion 93 of the inspection probe 9 comes into contact with the surface of the spot mark.

  When the lowering of the inspection probe 9 is completed, the quality of the spot nugget state is determined (S10). The pass / fail judgment will be described later. When the pass / fail determination is completed, the robot controller 2 retracts the air cylinder 6 and displaces the inspection probe 9 upward (S11).

  When the robot controller 2 receives a signal from the air cylinder 6 indicating that the degeneration operation of the air cylinder 6 has been completed, the robot controller 2 determines whether or not there is a spot mark to be inspected (S12), and the spot mark to be inspected remains. If it is present (S12: NO), the process returns to step S1, the manipulator 1 is activated, and detection of the next spot mark on the member W to be inspected is started. That is, in the robot control device 2, a signal indicating that the retracting operation of the air cylinder 6 has been completed is sent to the swing control device 3, and the swing control device 3 resumes image analysis.

  On the other hand, in step S12, when there is no spot mark to be inspected (S12: YES), the inspection operation ends (S13), and the robot control device 2 moves the manipulator 1 to the standby position and the inspection ends. .

  Next, the quality determination of the spot nugget state will be described. The pass / fail judgment is started when a signal indicating that the extension operation is completed is input from the air cylinder 6 to the robot controller 2. The robot control device 2 transmits a swing operation start signal to the swing control device 3, and transmits an echo detection start signal to the examination determination device 4. The swing control device 3 that has received the swing operation start signal starts the swing operation process shown in the flowchart of FIG.

  First, the horizontal swing device 7 is driven, and a search swing operation is started (S21). The horizontal oscillating device 7 starts a search oscillating operation for displacing the inspection probe 9 along the oscillating trajectory as shown in FIG. As shown in FIG. 5, the contact portion 93 of the inspection probe 9 is pressed against the member to be inspected W with a predetermined pressing force P by the air cylinder 6, and the base end portion of the inspection probe 9 is the horizontal swing device 7. Is displaced in the horizontal direction. Therefore, as shown in FIG. 4B, the central axis M of the inspection probe 9 is tilted by a small angle β in the direction (XY plane) perpendicular to the normal direction of the member W to be inspected. The main body 92 swings.

  Next, it is determined whether or not the level of the echo input from the examination determination device 4 exceeds a predetermined value (S22). After receiving the echo detection start signal, the inspection determination device 4 oscillates an ultrasonic wave in the inspection probe 9, converts the echo detection signal input from the inspection probe 9 into a digital signal, and sends it to the oscillation control device 3. You are typing. The swing control device 3 compares the echo level input from the examination determination device 4 with a predetermined value set in advance.

  If the echo level does not exceed the predetermined value (S22: NO), it is determined whether or not the search swing operation (the operation of moving P0 to P4 shown in FIG. 4A) has been completed (S23). . If not completed (S23: NO), the process returns to step S22, and the search swing operation is continued. On the other hand, if the process is completed (S23: YES), the echo level does not exceed a predetermined value in the search swing operation, so it is determined that the nugget state in the spot mark is defective (S29), and the swing operation process is performed. Is terminated. When the swing operation process is completed, the swing control device 3 sends a signal indicating the end to the robot control device 2.

  When the echo level exceeds a predetermined value (S22: YES), the search swing operation is stopped (S24). Next, for the determination swing operation, the swing center is changed and the swing trajectory is set (S25).

  Next, the horizontal swing device 7 is driven, and the determination swing operation is started (S26). The horizontal oscillating device 7 starts a determination oscillating operation for displacing the inspection probe 9 along the oscillating trajectory as shown in FIG. At this time, a start signal of the determination swing operation is transmitted to the robot controller 2. The robot control device 2 that has received the start signal transmits a start signal for determining whether the nugget is good or bad to the inspection determination device 4. The inspection determination device 4 determines whether the nugget state is normal or not based on the echo waveform. If the inspection determination device 4 determines that the nugget state is normal, the inspection determination device 4 immediately stops the determination process by the auto freeze function, and sends the auto freeze signal to the robot controller 2. Send to. When the robot control device 2 receives this auto freeze signal, it transmits a stop signal to the swing control device 3.

  In the swing control device 3, it is determined whether or not a stop signal is input from the robot control device 2 (S27). If the stop signal has not been input (S27: NO), it is determined whether or not the determination swing operation (the operation of moving P0 'to P12' shown in FIG. 6) has ended (S28). If not completed (S28: NO), the process returns to step S27, and the determination swing operation is continued. On the other hand, when the process is finished (S28: YES), since the inspection determination device 4 cannot determine that the nugget state is appropriate in the determination swing operation, it is determined that the nugget state in the spot mark is defective (S29). The swing operation process is terminated. When the swing operation process is completed, the swing control device 3 sends a signal indicating the end to the robot control device 2. The robot control device 2 that has received the signal transmits a stop signal for determining whether the nugget is good or bad to the inspection determination device 4.

  When a stop signal is input from the robot controller 2 (S27: YES), the determination swing operation is stopped (S30), and the swing operation process is ended.

  Next, the operation of the welding inspection system A1 will be described.

  In the present embodiment, since the search center of the determination swing operation is determined by the search swing operation, the time required for the determination swing operation is shortened. The time required for the entire swing operation is also shortened compared to the case of the determination swing operation alone.

  For example, when the determination swing operation is performed at the moving speed v ′ = 2 mm / sec on the trajectory (the number of divisions D ′ = 12 of the circle S ′ and the radius L ′ = 2 mm of the circle S ′) shown in FIG. The maximum time required for the end of the dynamic operation is {12 (= 12 × 2 mm / 2 mm / sec) + α} seconds. α is the time required for movement not related to the determination (movement from position P0 'to position P1' in FIG. 6 or movement along the circumference of circle S '). Since the movement speed of these movements is sufficiently faster than v ′, α is a negligible time.

  When the search swing operation is performed at the moving speed v = 4 mm / sec in the trajectory shown in FIG. 4A (the number of divisions D of the circle S = 4, the radius L of the circle S = 2 mm), the search swing operation ends. The maximum time required for this is {2 (= 4 × 2 mm / 4 mm / sec) + α} seconds. Subsequently, on the trajectory shown in FIG. 6 (the number of divisions D ′ of the circle S ′ = 12 and the radius L ′ of the circle S ′ = 0.5 mm), the determination swing operation was performed at the moving speed v ′ = 2 mm / sec. In this case, the maximum time required until the end of the determination swing operation is {3 (= 12 × 0.5 mm / 2 mm / sec) + α} seconds. Therefore, the maximum time required for the entire swing operation is {5 (= 2 + 3) + α} seconds, which is 7 (= 12−5) seconds (58.3%) shorter than the case of only the determination swing operation.

  Assuming that the average values of the actual required times of the search swing motion and the determination swing motion are each half of the maximum time, 3.5 {= (12/2) − (2/2) − (3/2)} second inspection time is shortened. For example, since there are about 3000 spot traces in one automobile, if the time taken to inspect each spot trace is reduced by 3.5 seconds, the inspection time can be reduced by about 3 hours. Note that the time required for the swinging operation can be further shortened by increasing the moving speed v in the search swinging operation or by reducing the radius L ′ of the circle S ′ in the determination swinging operation.

  In the above embodiment, when the search swing operation is completed without the echo level exceeding the predetermined value (YES in step S23 in FIG. 8), it is determined that the nugget state in the spot mark is defective. However, there is a possibility that the optimum posture may be obtained at a position deviating from the trajectory of the search swing motion. Therefore, the determination swing motion may be performed with the swing center and the operation distance L from the swing center as they are. Good.

  In the above-described embodiment, the two-stage swing operation of the search swing operation and the determination swing operation is performed. However, the search swing operation may be further performed in two steps or more.

  In the above embodiment, the inspection determination device 4 determines pass / fail during the determination swing operation after determining the swing center of the determination swing operation in the search swing operation. The determination device 4 may make a pass / fail determination. In this case, it is necessary to make the auto freeze function work when it is determined that the nugget state is normal even during the search swinging operation.

  In the above embodiment, when the echo level exceeds a predetermined value, the search rocking operation is stopped and the determination rocking operation is started. However, the present invention is not limited to this. For example, the posture of the inspection probe 9 with the maximum echo level may be stored, and the determination swing operation may be performed with the posture as the center. In this case, the flowchart of the swing operation process is as shown in FIG.

  First, the horizontal rocking device 7 is driven to start a search rocking operation (S31), zero is input as an initial value to the maximum value Emax of the echo level, and the initial posture of the rocking center is stored ( S32). Specifically, the coordinate value of the center position P0 in FIG. Next, it is determined whether or not the echo level E input from the examination determination device 4 is greater than the maximum value Emax (S33).

  If the echo level E does not exceed the maximum value Emax (S33: NO), the process proceeds to step S36. On the other hand, when the echo level E exceeds the maximum value Emax (S33: YES), the maximum value Emax is updated (S34), and the posture at that time is stored (S35). Specifically, the coordinate value of the center of the base end portion of the inspection probe 9 at that time in FIG.

  Next, it is determined whether or not the search swing operation has been completed (S36). If not completed (S36: NO), the process returns to step S33, and the search swing operation is continued. On the other hand, when the process is completed (S36: YES), the trajectory of swing is set with the stored posture as the swing center (S37), and the determination swing operation is performed (S38 to S42). Steps S38 to S42 are the same as steps S26 to S30 in the flowchart shown in FIG.

  In this case, although the time required for the search swing operation increases, the posture closer to the optimal posture is set as the center of the determination swing operation, so that the time required to reach the optimal posture can be reduced. Therefore, depending on the case, the time required for pass / fail judgment can be further shortened.

  In the above-described embodiment, the determination of stopping the search swing operation is performed based on whether or not the echo level exceeds a predetermined value, but the present invention is not limited to this. For example, an integrated value of an echo level for a predetermined time or an integrated value of an echo level exceeding a predetermined value may be used. Moreover, you may make it judge by these combinations.

  In the above embodiment, the robot control device 2, the swing control device 3, and the inspection determination device 4 are separate devices, but the present invention is not limited to this. You may comprise so that the function of two or all of these apparatuses may be implement | achieved by one computer.

  In the above embodiment, the inspection probe 9 is pressed against the member W to be inspected by the air cylinder 6 and the base end portion of the inspection probe 9 is displaced by the horizontal swing device 7, but these are performed by the manipulator 1. You may do it.

  FIG. 10 is a diagram for explaining the second embodiment of the welding inspection system according to the present invention, and is a block diagram showing the overall configuration of the welding inspection system A2. In the figure, the same or similar elements as those in the first embodiment are denoted by the same reference numerals. The welding inspection system A2 differs from the welding inspection system A1 in that the functions of the air cylinder 6 and the horizontal swing device 7 are performed by the manipulator 1. The welding inspection system A2 does not have the air cylinder 6 and the horizontal swing device 7, and does not have the swing drive device 10 for driving the horizontal swing device 7. Further, since there is no need to control the horizontal swing device 7, the swing control device 3 in the welding inspection system A1 is a positioning control device 3 'that performs only positioning control.

  Since the welding inspection system A2 does not require the air cylinder 6, the horizontal rocking device 7, and the rocking drive device 10, the cost for these devices can be reduced. Moreover, since the attachment of the inspection probe 9 to the manipulator 1 is simplified, the positioning accuracy of the inspection probe 9 is improved. In addition, cable wiring that is a signal input / output path between the devices is reduced.

  In the above-described embodiment, the ultrasonic emission direction is changed by displacing the base end portion in a state where the tip of the inspection probe 9 is pressed against the member to be inspected W. However, the ultrasonic emission is performed by other methods. The direction may be changed.

  The welding inspection system according to the present invention is not limited to the above-described embodiment. The specific configuration of each part of the welding inspection system according to the present invention can be varied in design in various ways.

It is a block diagram showing the whole composition of a 1st embodiment of the welding inspection system concerning the present invention. It is a figure which shows the structure of an inspection probe vicinity. It is a wave form diagram displayed on a monitor of an inspection judging device in case a nugget state is normal. It is a figure for demonstrating the 1st rocking locus of a test | inspection probe. It is a figure for demonstrating the tilted inspection probe. It is a figure for demonstrating the 2nd rocking locus of a test | inspection probe. It is a flowchart for demonstrating the test | inspection procedure of the welding test | inspection system concerning 1st Embodiment. It is a flowchart for demonstrating the rocking | fluctuation operation process performed with a rocking | fluctuation control apparatus. It is a flowchart for demonstrating another rocking | fluctuation operation process. It is a block diagram which shows the whole structure of 2nd Embodiment of the welding inspection system which concerns on this invention. It is sectional drawing of a to-be-inspected member.

Explanation of symbols

1 Manipulator (displacement means, pushing means)
2 Robot control device 3 Swing control device (first control means, second control means, center emission direction determination means)
4 Inspection determination device (nugget state determination means)
5 CCD camera 6 Air cylinder (pressing means)
7 Horizontal swing device (displacement means)
71 X-direction swing device 72 Y-direction swing device 8 Elastic member 9 Inspection probe (probe means)
92 Main body 93 Contact portion 10 Swing drive device N Nugget W Member to be inspected

Claims (6)

A welding inspection system for inspecting whether or not the state of the nugget formed in the welded portion is appropriate using the reflected wave by emitting ultrasonic waves to the welded portion of the member to be inspected,
Probe means that contacts the weld and enters and exits the ultrasonic wave and its reflected wave;
First control means for sequentially changing the emission direction of the ultrasonic waves in a plurality of preset directions centered on a predetermined direction;
Based on the level of the reflected wave from the weld of the ultrasonic wave detected by the probe means during the period in which the first control means changes the emission direction of the ultrasonic wave, Center emission direction determining means for determining a direction close to the sound wave emission direction as the center emission direction;
The ultrasonic wave emission direction is sequentially changed to a plurality of preset directions with the central emission direction determined by the central emission direction determination unit as a center, which is greater than the direction changed by the first control unit. A second control means;
Based on the waveform of the level of the reflected wave from the weld of the ultrasonic wave detected by the probe means during the period in which the second control unit changes the emission direction of the ultrasonic wave, the weld Nugget state determination means for determining whether or not the nugget state is appropriate,
With
When the nugget state determination means determines that the state of the nugget is appropriate, the inspection of the weld is terminated.
Welding inspection system characterized by that. A displacement means attached to the probe means via an elastic member, and displacing the probe means in a direction perpendicular to the predetermined direction;
A pressing means for pressing the probe means with a predetermined pressing force substantially perpendicularly to the weld,
Further comprising
The welding inspection system according to claim 1. The displacement means and the pressing means are manipulators,
The welding inspection system according to claim 2. The angle formed by the center emission direction determined by the center emission direction determining means and the emission direction changed by the second control means is the predetermined direction and the emission direction changed by the first control means. Smaller than the angle,
The welding inspection system according to claim 1. The center emission direction determination means determines the emission direction when the reflected wave level becomes a predetermined level or more as the center emission direction when the first control means changes the emission direction of the ultrasonic waves. ,
The welding inspection system according to claim 1. The center emission direction determining means determines the emission direction when the level of the reflected wave is maximum as the center emission direction.
The welding inspection system according to claim 1.

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