JP2007152371A - Inspection system of welding spot position - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection system of welding spot positions, a system that reduces the number of processes for inspecting spot positions by extracting the spot welding positions as three-dimensional information and comparing it with CAD data. <P>SOLUTION: The system includes: an indicator 10 for pointing out the positions of spots 60 of the spot welding performed on a workpiece such as an automobile body; a pair of cameras arranged away from each other by a prescribed distance; an identifying section 13 comprising three light emitting elements 13A, 13B, 13C attached to the indicator 10 in a manner unaligned with one another; and a decision section which, on the basis of an imaging signal from each camera, calculates the three-dimensional position of the spot 60 in contact with the indicator 10, from the position of each light emitting element on its image in the identifying section, and which decides the correct position of the spot 60 of the spot welding performed on the workpiece by collating it with the three-dimensional position of the spot preliminarily registered. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a welding spot position inspection system that is used in a process of manufacturing a body of an automobile and inspects the position of a spot welding mark (hereinafter referred to as a spot) applied to a workpiece.

  In the body process of automobile production, the pressed steel sheet is joined using an automated welding robot or the like to form the skeleton of the automobile body. In the body process, the number (number) and position (position) of spot welding spots applied to the body are confirmed. Hereinafter, such confirmation work is referred to as NP check.

  As a method of NP check, conventionally, an operator checks the position and number of hit points after spot welding by checking the spot-welded body and its design drawing one by one. However, such work requires a lot of time and labor since there are about 4000 spot welding spots per vehicle.

Therefore, in order to reduce the labor of the worker, a system for performing an NP check using a computer can be considered.
As shown in FIG. 7, the NP check system 100 includes a two-dimensional position measuring device 110 having a camera 102 disposed at the tip of a movable arm 101 and a personal computer 120. In the NP check system 100, the personal computer 120 receives data of an image captured by the camera 102, analyzes the image to calculate the position of the hit point, and stores the calculated hit point position in the personal computer 120 in advance. It is determined whether or not the position of the spot welding spot spot applied to the body is within the allowable range as compared with the position of the design data hitting point.

  However, in the NP check system 100 shown in FIG. 7, when the spot welding hit point position is calculated, the base data is two-dimensional data captured by the camera. 3D CAD (computer-aided design) data is difficult to collate.

  In addition, since the range that can be captured by the camera 102 is limited, it is necessary to perform camera shooting several times when performing NP check of one vehicle. When calculating the position of the hit point in the image data captured at each imaging position, it is necessary to calculate the position in absolute coordinates and to set the origin serving as a reference for absolute coordinates. Such setting of the origin is cumbersome and needs to be performed before the inspection. In addition, since it is necessary to set the origin accurately, there is a problem that preparation man-hours increase.

  Further, when the shape of the workpiece is three-dimensionally complicated, if the data referred to by the personal computer 120 is two-dimensional position information, there is a possibility that the collation determination may be mistaken. Further, such a misjudgment may occur due to variations in the shape of the spot welding dent.

  The present invention was created in view of such circumstances, and by extracting the spot welding spot position as three-dimensional information and comparing it with CAD data, the number of spot welding spot position inspections can be reduced. It aims at providing the welding spot position inspection system which aims at reduction.

  In order to achieve the above object, a welding spot position inspection system according to the present invention is provided in an indicator that indicates the position of a spot welding spot applied to a workpiece such as an automobile body and the indicator so as not to be in line with each other. An identification unit composed of three light emitting elements, a pair of cameras arranged toward the identification unit and spaced apart from each other by a predetermined interval, and an indication from the position of each light emitting element based on an imaging signal from each camera Calculates the 3D position of the hitting point that the tool is in contact with, and compares it with the registered 3D position of the hitting point in advance to determine whether the spot welding spot position on the workpiece is in the correct position. And a determination unit.

  In the welding spot position inspection system of the present invention, preferably, the light emitting element is an infrared light emitting element and the camera is an infrared camera. In the present invention, it is preferable that the pointing device is composed of a rod-shaped protruding portion and a flat portion fixed to one end of the protruding portion, and the light emitting element of the identification portion is provided on the surface of the flat portion. It has been.

In this way, the welding spot position inspection of the present invention makes it possible to recognize the three-dimensional position of the spot by instructing the spot with the pointing tool, and by comparing with CAD data whether the position is correct or not. Whether or not is the correct position can be automatically determined.
In addition, since the operator can detect the three-dimensional position of the point of hitting by making the tip of the pointing tool contact the spot of spot welding, there is no need to check the position while looking at the drawing, which is very simple. Inspection can be completed in a short time by work. Therefore, according to the welding spot position inspection system of the present invention, the inspection man-hour can be greatly reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a view showing a welding spot position inspection system 1 according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a region A in FIG.
As shown in the figure, the welding spot position inspection system 1 includes a pointing tool 10 that indicates the position of a spot (ie, spot) 60 that has been spot welded on a workpiece 50 such as a body, and a calibration that is attached to the workpiece 50 and outputs a reference. , A camera unit 30 including a pair of cameras disposed toward the pointing tool 10 and the calibration marker 20, and a personal computer 40 as a determination unit.

As shown in FIG. 2, the indicator 10 includes a rod-like protrusion 11, a flat part 12 fixed to one end of the protrusion 11, an identification part 13 provided on a flat surface of the flat part 12, It is composed of In addition, the protrusion part 11 and the flat part 12 are comprised, for example with a hard material, and the indicator 10 maintains a fixed form by these.
Here, the identification unit 13 includes three infrared light emitting elements 13A, 13B, and 13C fixedly arranged on a plane on the flat portion 12. The three infrared light emitting elements 13A, 13B, and 13C are arranged, for example, at the vertices of a triangle, preferably at the vertices of an equilateral triangle so as not to be aligned on a straight line. Then, on the extension of a line that passes through the center of gravity of a triangle defined by connecting each infrared light emitting element 13A, 13B, 13C with a line and is perpendicular to the plane of the flat portion 12 on which the infrared light emitting elements 13A, 13B, 13C are installed. The tip 10A of the indicator 10 is located at Each infrared light emitting element 13A, 13B, 13C is configured to be lit by a drive circuit (not shown) when a button 11A attached to the protruding portion 11 is pressed.

  Next, the calibration marker 20 is attached to the workpiece 50 for use. For example, the calibration marker 20 is also composed of an infrared light emitting element and always emits light. As will be described later, the calibration marker 20 is used to calibrate (calibrate) the origin of CAD data and the origin of measurement data. In addition, the calibration marker 20 is each installed in the some site | part of the workpiece | work 50 decided beforehand, for example, the relative positional relationship of those calibration markers 20 is considered, The origin of measurement data is set by the personal computer 40.

  Next, as shown in FIG. 3, the camera unit 30 is configured as a stereo camera including a pair of cameras 31 and 32 that are fixedly held at a predetermined distance D from each other. It is fixedly arranged on the section 35 (FIG. 1) and connected to the personal computer 40 via the cable 36. Each camera 31, 32 is an infrared camera. Thereby, each camera 31 and 32 images the calibration marker 20, images the identification unit 13 of the pointing tool 10 brought with respect to the hit point position of the work 50, and the personal image signal to be described later. The data is sent to the computer 40.

Next, the personal computer 40 will be described. The personal computer 40 may have a known configuration, and the following functions can be realized by operating software.
That is, the personal computer 40 receives the imaging signals from the cameras 31 and 32 of the camera unit 30 and reads the positions of the plurality of calibration markers 20 on the screen by image processing. Since the position of each calibration marker 20 is determined in advance in the design data, the origin is set for the measurement data from the relative positional relationship of each calibration marker 20 extracted from the imaging signal.

Further, the personal computer 40 receives imaging signals from the cameras 31 and 32 of the camera unit 30, and reads the positions of the infrared light emitting elements 13A, 13B, and 13C of the identification unit 13 on the screen by image processing.
The personal computer 40 then uses the infrared light emitting elements according to the so-called triangulation and stereoscopic theory based on the positions of the infrared light emitting elements 13A, 13B, and 13C on the screens of both the cameras 31 and 32 on the screen. The three-dimensional positions of 13A, 13B, and 13C are calculated. That is, as shown in FIG. 3, using two cameras 31, 32, each infrared light emitting element 13A, 13B, 13C attached to the pointing device 10 is captured by the two cameras 31, 32, and the personal computer 40 is used. Thus, the position of each infrared light emitting element 13A, 13B, 13C is calculated according to the principle of triangulation.

  Furthermore, the personal computer 40 considers that the direction and distance from the attachment position to the tip of each infrared light emitting element 13A, 13B, 13C in the pointing tool 10 are constant, and each infrared light emitting element 13A, 13B, 13C. The three-dimensional position (x, y, z) of the tip 10A of the pointing tool 10 when the light is emitted is calculated. The three-dimensional position (x, y, z) of the tip 10A of the pointing tool 10 referred to here means that the tip 10A of the pointing tool 10 contacts a spot welding hit point 60 (see FIG. 2) as will be described later. In other words, it is the three-dimensional position (x, y, z) of the spot welding spot 60.

  Next, the personal computer 40 collates the three-dimensional position (hereinafter referred to as detection data) of the tip of the pointing tool 10 with CAD data. Here, the CAD data has the three-dimensional position coordinates of the hit point 60 in advance, and the personal computer 40 collates the coordinates of the hit point 60 one by one. Then, the personal computer 40 determines whether or not the detected data is within a certain allowable range with respect to the CAD data. The allowable error is arbitrary. Furthermore, the personal computer 40 can display the determination result on a display or print it on a print sheet.

  Since the personal computer 40 confirms the position of the welding spot for various workpieces, prior to the spot welding spot position inspection work, the personal computer 40 receives a signal for designating the workpiece type, for example, the vehicle type, and executes the spot position inspection program. The CAD data including the three-dimensional coordinates of the hit points on the design data is read from a storage device such as a hard disk corresponding to the work type, for example, the car type.

The welding spot position inspection system 1 according to the embodiment of the present invention is configured as described above, and an inspection operation of the welding spot position using the inspection system 1 will be described.
First, preparation work for starting inspection is performed. A work 50 to be inspected, that is, a vehicle is carried into a work place where the welding spot position inspection system 1 is installed. Then, the personal computer 40 is activated, a work type, for example, a vehicle type signal is input, and a hit point position inspection program is activated. Further, as shown in FIG. 4, calibration markers 20 are attached to a plurality of predetermined parts of the workpiece 50, and these calibration markers 20 are photographed by the camera unit 30, and the camera unit 30 is photographed by the personal computer 40. 50 imaging signals are transmitted. Then, the personal computer 40 sets the origin for the measurement target imaged by the camera unit 30 from the relative positional relationship of the calibration markers 20 extracted from the imaging signal. In this way, the preparation work for starting the inspection is completed.

Next, the inspection is started. FIG. 5 is a flowchart of the dot inspection.
First, in step S1, when the personal computer 40 receives an inspection start instruction from the operator, the personal computer 40 displays a regular dot position to be checked on the display 41 as shown in FIG. In the illustrated example, six regular hit points are displayed on the display 41. Thereby, the operator can check the approximate position and the number of hit points 60 of spot welding in advance by looking at the display 41.

Next, in step S2, the operator applies the tip 10A of the pointing tool 10 to the hitting point 60 based on the display on the display 41, and the tip 10A of the pointing tool 10 is in contact with the hitting point 60 in step S3. The button 11A for making each infrared light emitting element 13A, 13B, 13C emit light is pushed.
In step S4, the worker activates the cameras 31 and 32 in a state where each infrared light emitting element 13A, 13B, and 13C emits light, and the worker contacts the tip 60 of the pointing tool 10 with the hit point 60. The three infrared light emitting elements 13A, 13B, and 13C are photographed. Imaging signals including images of the work 50 photographed by the cameras 31 and 32 and the infrared light emitting elements 13A, 13B, and 13C are sent to the personal computer 40.

  In step S5, the personal computer 40 determines each infrared light emitting element 13A, 13B, 13C on both screens 31 and 32 on the screen and the distance between them according to the so-called triangulation and stereoscopic vision theory. The three-dimensional positions of the infrared light emitting elements 13A, 13B, and 13C are measured. And based on the information of the three-dimensional position of each infrared light emitting element 13A, 13B, 13C, the three-dimensional position of the tip 10A of the pointing tool 10 is calculated. Thereby, the three-dimensional position of the hitting point where the tip 10A of the pointing tool 10 is in contact can be acquired. In step S6, the cameras 31 and 32 are stopped, and the information on the three-dimensional position of the hit point 60 obtained in step S7 is stored in a storage device such as a hard disk of the personal computer 40.

  Such measurement of the position of the hit point 60 is repeated by the number of hit points 60. Since the range that can be captured by the cameras 31 and 32 at a time is determined, in order to inspect the number of hits of the entire vehicle, the above operation is repeated by changing the installation location of the camera unit 30.

  When the measurement is completed for all the hit points 60, in step S8, the three-dimensional coordinates of the hit points on the CAD data and the three-dimensional coordinates of the obtained hit points are collated one by one, and the measured hit points are within a predetermined allowable range. It is determined whether or not it is inside.

  Then, information on the determination result for each hit point is stored in a storage device such as a hard disk of the personal computer 40. The information of the determination result is displayed on the display of the personal computer 40 or printed on a print sheet according to the operator's request. By displaying the result or printing and outputting the result in this way, the operator can confirm the result of the position inspection of the spot welding spot.

  As described above, according to the welding spot position inspection system 1 according to the embodiment of the present invention, when the portable welding tool 10 is used to inspect the position of the spot welding spot 60, it is provided in the pointing tool 10. By using the identification unit 13 and the pair of cameras 31 and 32, the three-dimensional position with respect to the hit point 60 that is in contact with the tip 10A of the pointing tool 10 is calculated, and the position data of the hit point defined on the design data by the personal computer 40 and By collating, it is possible to automatically determine whether or not the spot welding spot 60 is in the correct position.

  Thus, since the welding spot position inspection system 1 can calculate the three-dimensional position of the spot welding spot 60 applied to the workpiece 50, it can be easily compared with the CAD data. Moreover, the origin of measurement data can be easily calibrated by sticking the calibration marker 20 to the workpiece 50. In addition, since the operator performs the position inspection of the spot 60 by pointing the spot welding point 60 using the pointing tool 10 one by one, it is possible to prevent erroneous determination.

  Furthermore, since the operator can detect the three-dimensional position of the hitting point 60 by bringing the tip 10A of the pointing tool 10 into contact with the spot welding hitting point 60, there is no need to check the position while viewing the drawing. Inspection can be completed in a short time by a very simple operation. Therefore, according to the welding spot position inspection system 1, the number of inspection steps can be reduced. As a result, it is possible to shorten the inspection work that conventionally required 72 hours for one unit to about 12 hours.

Although detailed above, the present invention can be implemented in various forms without departing from the spirit of the present invention. For example, in the above-described embodiment, the personal computer 40 is used as the determination unit. However, the present invention is not limited to this, and a dedicated electronic computer can also be used as the determination device.
In the above-described embodiment, the infrared light emitting elements 13A, 13B, and 13C are used as the light emitting elements of the identification unit 13, and the infrared cameras 31 and 32 are used as the camera unit 30, but the present invention is not limited thereto. Obviously, other types of cameras may be used.
In the above description, the vehicle body is exemplified as the workpiece. However, the present invention is not limited to the body, and the present invention can be applied to other workpieces such as a vehicle door subjected to spot welding. is there.

It is a figure showing a welding spot position inspection system concerning an embodiment of the present invention. It is an enlarged view of the area | region A in FIG. It is a figure which shows the camera and indicator which concern on embodiment of this invention. It is a figure which shows the state which attached the calibration marker to the predetermined some site | part of a workpiece | work. It is a flowchart of the spot inspection in the welding spot position inspection system which concerns on embodiment of this invention. It is a figure which shows the display state of the regular dot position to check on a display. It is a figure which shows the conventional NP check system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Welding point position inspection system 10 Indicator 11 Protrusion part 11A Button 12 Flat part 13 Identification part 13A, 13B, 13C Infrared light emitting element 20 Calibration marker 30 Camera part 31, 32 Camera 35 Support part 36 Cable 40 Personal computer 50 Work 60 RBI

Claims (3)

An indicator indicating the position of the spot welding spot applied to a workpiece such as an automobile body,
An identification unit composed of three light emitting elements provided in the indicator so as not to be in line with each other;
A pair of cameras arranged toward the identification unit and separated from each other by a predetermined distance;
Based on the image pickup signal from each camera, the three-dimensional position of the hit point that the indicator is in contact with is calculated from the position of each light emitting element, and is compared with the three-dimensional position of the hit point registered in advance. A welding spot position inspection system, comprising: a determination unit that determines whether or not a spot position by spot welding applied to is in a correct position.   The welding spot position inspection system according to claim 1, wherein the light emitting element is an infrared light emitting element, and each of the cameras is an infrared camera. The indicator is composed of a rod-like projecting portion and a flat portion fixed to one end of the projecting portion, and the light emitting element of the identification portion is provided on the surface of the flat portion. The welding spot position inspection system according to claim 1 or 2.

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