JP2772895B2 - Ultrasonic method for measuring spot welds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for arranging a spot weld in water and setting a water distance from a focusing probe so that a beam focus is located below the spot weld. The present invention relates to a method for measuring a spot weld using sound waves.

[0002]

2. Description of the Related Art A spot weld is arranged in water, and a water distance from a focusing probe is set so that a beam focus is located below the spot weld. The measuring method is, for example, “welding technique” 19
It is disclosed in March, 1989, issue, pages 60 to 65, "Ultrasonic measurement of resistance spot welds by image processing". The technique described in the above-mentioned magazine is also disclosed in the Journal of the Japan Welding Society, Vol. Have been.

According to an article in the magazine, for example, when a probe is run in the X direction and a cross section near a weld is viewed, FIG.
"Comparison between cross section and scanning graph" can be performed as shown in FIG. In other words, "the two ends of the scanning graph are non-joined portions and indicate a boundary eco-height of 20, but as they approach the joined portion, multiple reflections with the joined bottom surface gradually increase, and a part of the reflected wave from the bottom surface is reduced. Eco-friendly because it is blocked by the border
The height decreases 21. Beyond the joint boundary, multiple reflections with the joint bottom surface increase, and the eco-height increases again. At the center of the joint, the bottom eco-height of the joined lower base material is mainly 23. (See page 62). Then, the graphs are collected and subjected to image processing to determine the nugget portion.

[0004]

In this graph, the existence of the nugget portion is determined by the increase in the eco-height and the appearance of the top portion. However, depending on the height of the top portion, the nugget portion is determined. May not exist, so
Experiments have shown that the boundary between the corona bond and the nugget is also difficult to understand. Therefore, even in the case where the nugget part is not actually configured, there is a possibility that the image is displayed as if the nugget is configured.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to compare the position of the top in the scanning graph with a reference value, and then compare the nugget position with the reference value. After determining the success or failure of
It is an object of the present invention to provide a method for measuring a spot weld by ultrasonic waves, which can accurately detect the whole nugget.

[0006]

In order to achieve the above object, a method for measuring a spot welded portion by ultrasonic waves according to the present invention comprises scanning a probe at a constant pitch in each of an X direction and a Y direction. Scan graph of interface echoes and the minimum interface echo value and non-junction boundary
Set in advance a reference value from a surface echo height, as compared to the reference value of the peak value the predetermined interfacial echo in the scanning graph, if the peak value is larger than the reference value, both sides of the peak portion Is determined as a nugget component, and the entire nugget is detected by integrating the nugget components.

[0007]

With the configuration described above, the focusing probe is set to X
Each scan graph is obtained while moving at a constant pitch in the axial direction and the Y-axis direction, and the peak value of the interface echo in the scan graph is compared with a reference value. If the value is larger than the value, it is determined that there is a nugget configuration, and the size of the nugget is determined. Then, the respective scan graphs determined to have the structure of the nugget are accumulated, and the whole image of the nugget is detected from the accumulated data. If the nugget is determined not to be composed, its data is not included in the accumulation, so that the detection of the entire nugget becomes extremely accurate.

[0008]

An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a configuration diagram of a nugget monitor suitable for use in the measurement of a spot weld by ultrasonic waves according to the present invention, wherein 1 is a focusing probe, which is disposed in a water tank 2. The welding member 3 to be measured is also immersed in the water tank 2. The water distance between the focusing probe 1 and the welding member 3 is shorter than the focal length of the beam of the focusing probe 1. Reference numeral 4 denotes a scanner which moves the focusing probe 1 at a constant pitch in the X-axis direction or the Y-axis direction. The scanner 4 performs the search while moving the focusing probe 1 in a predetermined direction. The boundary echo signal at the point is sent to the pulsar receiver 5. 6 and 7, the focusing probe 1 is X
Sensors for limiting both ends of movement in the case of moving in the direction, and sensors 6 and 8 are sensors in the Y direction.

The boundary echo signal at each point is accumulated by the peak detector 9, for example, the boundary echo value at each point in the X direction at Y = 0 is accumulated, and FIG.
Is generated. And
The peak value 11 of the interface eco in the graph 10 is compared with a predetermined reference value described later, and if the peak value is larger than the reference value, it is displayed on both sides of the peak portion. It is determined that the part between the minimum interface eco-values 12 and 13 is the nugget component. The data determined to have this nugget component is sent to the A / D board 14.

The above operation is performed at a constant pitch in the X direction and the Y direction, respectively, and these are performed by the A / D converter.
When it is sent to the board 14, it is integrated and digitized and displayed on the CPU 15 as a whole view of the nugget as a plan view in FIG. 3 or a side view as in FIG. 3 and 4, the nugget diameter D, the center of the nugget 0, the corona bond zone 16 and the like can be clearly determined.

FIG. 2 shows a transducer having a diameter of 12.5 mm, a focal length of 25.4 mm, and a frequency of 10 MHz. Water distance 18.
5 mm. Under the condition of a plate thickness of 0.8 mm × 0.8 mm, the thin line scan graph 10 shows a case where a nugget is sufficiently formed, and the thick line scan graph 17 shows a case where a nugget is not formed.

As a result of the experiment, the peak value 11 when the nugget is sufficiently formed varies slightly depending on the plate thickness, but is about 55 from the lowest interface echo value 12 to the non-joint interface echo height 18. %. Since the thickness may be close to 60% and the thickness may be close to 50%, the nugget is formed by comparing these values with the peak value 11 using these values as reference values. And the boundaries of the nugget at that time. Also, the thick line scanning graph 1
The peak value 19 at 7 is in the range of 55% or less and is usually
In the case of the plate thickness of, it is determined that the nugget is not formed because it is below the reference value.

As described above, in the method of measuring a spot welded portion by ultrasonic waves according to the present invention, each scanning graph is obtained while moving the focusing probe 1 at a constant pitch in the X-axis direction and the Y-axis direction. The presence or absence of a nugget configuration and the size of the nugget are determined on the scan graph.

[0014]

According to the present invention, the probe is scanned at a constant pitch in each of the X direction and the Y direction to obtain a scanning graph of the interface echo in each direction and to obtain the lowest interface echo value.
Reference value is set in advance from the height of the interface echo at the non-joined part
And, compared with the reference value of the peak value the predetermined interfacial echo in the scanning graph, if the peak value is larger than the reference value, while the minimum surfactant echo values displayed on both sides of the peak portion It was determined that the nugget components. Thus to detect a full picture of the nugget by integrating the nugget components, nuggets of whether is configured determine
The fracture is the lowest interfacial echo value and the non-zygosity interface echo height
Thus, the nugget is clearly distinguished by using a reference value set in advance and no erroneous information is given, and at this time, the whole picture of the nugget can be accurately measured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a nugget monitor suitable for use in measuring a spot weld by ultrasonic waves according to the present invention.

FIG. 2 is an exemplary diagram of a scanning graph.

FIG. 3 is a plan view of the entire nugget obtained by the measuring method according to the present invention.

FIG. 4 is a side view thereof.

FIG. 5 is a known scanning graph.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Focusing probe 2 Water tank 3 Welding member 10, 17 Scan graph 11 Peak value of interface echo 12, 13 Minimum interface eco value

Claims (1)

(57) [Claims] 1. A spot welding part is placed in water, and a water distance from a focusing probe is set so that a beam focus is located below the spot welding part, and the spot welding part is measured by ultrasonic waves. In the method, the probe is X
Scanning at a constant pitch in each of the direction and the Y direction to obtain a scanning graph of the interface echo in each direction.
From the lowest interface echo value and the non-joint interface echo height
Set in advance a reference value, the peak value of the interface echo in the scanning graph compared with the predetermined reference value, a minimum the peak value is greater than the reference value, which is displayed on both sides of the peak portion A method for measuring a spot welded portion by ultrasonic waves, wherein a portion between the interface echo values is determined to be a nugget component, and the entire nugget is detected by integrating the nugget components.