JPS588954B2 - Seam welding ultrasonic inspection equipment - Google Patents

Description

[Detailed Description of the Invention] This invention provides in-process (
In Process) This relates to a non-destructive testing device.

Conventionally, an effective in-process inspection device using ultrasonic waves has been invented for spot welding, but no such effective in-process inspection device exists for seam welding.

This invention provides a device that performs in-process non-destructive testing using a single transducer, in which an ultrasonic transducer for transmitting and receiving is attached to one electrode to send out pulsed ultrasonic waves, and the other electrode The welding condition is quantitatively determined by detecting the ultrasonic waves reflected by the ultrasonic reflecting surface provided on the welding surface and by detecting the change in the wave height value.

First, the temporal change in the peak value of the ultrasonic reflected wave during welding time, which is the basis of this invention, will be explained based on the results of an experiment.

Figure 1 is a diagram showing the arrangement of electrodes, ultrasonic vibrators, and materials to be welded, and the progress state of ultrasonic waves during welding using a device to which this invention is applied, and Figure 2 is a diagram showing the progress of ultrasonic waves detected by the vibrator and displayed on a cathode ray tube. In this figure, 1 is an electrode, 2 is an ultrasonic transducer for transmitting and receiving, and a hole 3 made in electrode 1 is a diagram showing a multiple reflection waveform.
It is attached to the inner end surface 31 of.

Reference numeral 4 denotes the other electrode facing the electrode 1, 5 a hole formed in the electrode 4, and 51 an inner end surface of the hole 5 forming an ultrasonic reflecting surface.

6 is the tip surface of electrode 1, 7 is the tip surface of electrode 4, 8 and 9
are the materials to be welded, 10 is the contact surface of the materials 8 and 9 to be welded,
11 is a contact surface of the material to be welded 8 with the tip surface 6 of the electrode 1; 12;
13 is the contact surface of the welding material 9 with the tip surface 7 of the electrode 4; 13 drives the ultrasonic vibrator 2; and detects an electric signal converted when an ultrasonic reflected wave is input to the ultrasonic vibrator 2. It is a transmitting and receiving device.

T is a transmitted wave, B1 is a first reflected wave that is a combination of the reflected waves of the transmitted wave T reflected at the tip surface 6 and contact surfaces 10, 11, and 12 of the electrode 1, and input to the vibrator 2; The first reflected wave B1 is reflected from the inner end surface 31 of the hole 3 of the electrode 1.
C is the second reflected wave that travels in the direction of the electrode 4 again and is reflected and synthesized at the tip surface 6 and the contact surfaces 10, 11 and 12 of the electrode 1. , 11 and 12 is reflected by the ultrasonic reflecting surface 51, and then transmitted again through the contact surfaces 10, 11 and 12, and reaches the vibrator 2.

The main components of the first reflected wave B1 are the contact surface 11 and the electrode 1.
The reflected wave B1 monotonically decreases as the contact state between the contact surface 11 and the electrode 1 improves and the contact area increases as the energization time elapses.

Further, the reflected wave B2 changes substantially in a manner similar to that of the reflected wave B1.

On the other hand, since the reflected wave C from the reflecting surface 51 passes through the weld twice, it is affected by changes in physical properties due to the temperature rise of the welded materials 8 and 9, so it may not be as accurate as the reflected waves B1 and B2. It doesn't change.

Figure 3 is a diagram showing the relationship between welding time and the peak value of reflected wave C, from time 0 when welding current begins to flow to a certain point A.
The peak value of the reflected wave C increases monotonically as the welding time passes.

The reason for this is that the temperature of the contact surfaces 10, 11 and 12 increases with the passage of welding time, and the contact condition improves.

Furthermore, as the welding time elapses, it rapidly decreases from time A to time B.

When inspecting the cross section of the welded part, it is found that a minute molten part (nugget) begins to form in the process from time A to time B.

That is, the change from time A to time B is considered to be due to the rapid attenuation of the ultrasonic waves when the metal near the bonding surface 10 undergoes a phase change from solid to liquid phase.

Therefore, by detecting this time point B, it is possible to detect whether or not a melted portion is formed.

As the energization time further elapses, the peak value of the reflected wave C increases again, and the energization ends at time D.

FIG. 4 is a diagram showing the relationship between the difference H2-H1 between the peak value H2 at the end of the energization time D of the reflected wave C and the peak value H1 at the time B and the diameter of the molten part. A good correlation has been obtained.

Therefore, by selectively detecting the reflected wave C by a gate circuit, detecting the peak value H2 of the reflected wave at the end of the energization time and the peak value H1 at time B, and calculating the difference H2 - H1. Since it is possible to know the diameter of the fused portion that is formed, it is possible to make a highly reliable estimate of the quality of the welded portion from this.

In addition, compared to the conventional transmission method that has two transducers, one for transmitting and the other for receiving, which is used in spot welding inspection equipment, the method of this invention passes through the weld twice, so it is difficult to melt. The change in the peak value of the ultrasonic reflected wave corresponding to the diameter of the part increases, and more accurate results can be obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ultrasonic inspection apparatus for seam welding according to the present invention will be described below with reference to the drawings.

FIG. 5 is a front view showing the configuration of an embodiment of the ultrasonic inspection apparatus for seam welding according to the present invention, and FIG. 6 is a sectional view taken along line 1--2 in FIG.

In the figure, reference numerals 14 and 15 indicate a pair of disc-shaped electrodes that weld the materials 8 and 9 to be welded by applying current to them while sandwiching and applying pressure;
a, 16b, 16c, 16a are one of the disk-shaped electrodes 1
A plurality of holes drilled along the circumference of 4, 17a, 17
b, 17c, 17d are these holes 16a, 16b, 16c,
The ultrasonic transducers 16d are each incorporated in the ultrasonic transducers 16d, and are connected to the transmitting/receiving device 13 via lead wires 18a, 18b, 18c, and 18d.

19 is an ultrasonic reflecting surface provided along the circumference of the other disc-shaped electrode 15, and 20 is a molten part (nugget) formed in the materials to be welded 8, 9.

Next, the operation of an embodiment of the ultrasonic inspection apparatus for seam welding according to the present invention configured as described above will be explained based on the drawings.

First, the materials to be welded 8 and 9 are sandwiched between a pair of disc-shaped electrodes 14 and 15, and when the current is applied while applying pressure and the materials are rotated in the directions of arrows A and B in the figure, the materials to be welded 8 and 9 are moved in the direction of arrow C. While moving, a fused portion 20 is formed inside and seam welding is performed.

Now, the transmitter/receiver 13 is activated to transmit the ultrasonic transducers 17a, 1.
When ultrasonic waves are transmitted from 7b, 17c, and 17d, the ultrasonic waves transmitted to a position away from the welding portion are reflected by the circumferential surface of one disc-shaped electrode 14 and return to the ultrasonic transducer L7a.
, 17b, 17c, and 17d.

(B1 wave in the figure) On the other hand, a part of the ultrasonic wave (T wave in the figure) sent out on the line connecting the centers of both disc-shaped electrodes 14 and 15 passes through the welding part and passes through the other disc-shaped electrode. The ultrasonic wave reaches an ultrasonic reflector 19 provided at 15, where it is reflected and returns to its original state.

(Wave C in the figure) This C wave passes through the weld twice, so it changes significantly depending on the physical condition of the weld, that is, whether the joint is melted or not. The degree of permeability varies depending on the size of the melted portion 20.

Therefore, by detecting the magnitude of this C wave, it is possible to determine the weld contact state of the weld for the reason explained in detail above.

In this embodiment, four ultrasonic vibrators are incorporated, so four spots on the seam welding line can be spot-inspected while the disc-shaped electrode 14 goes around once. If the number of children is increased, inspection of finer pitches becomes possible.

FIG. 7 and FIG. 8 show a pair of electrodes and one disc-shaped electrode 14.
This is a diagram showing a case where the backing money 2 is composed of the backing money 21 and the backing money 21.
1 is formed with an ultrasonic reflecting surface 22, which performs the same function as that of the embodiment shown in FIGS. 5 and 6.

As is clear from the above description, this invention involves sandwiching stacked materials to be welded from both sides between a pair of disc-shaped electrodes or a single disc-shaped electrode and a backing metal, and welding by applying pressure and electricity. In a welding device, an ultrasonic transducer placed on one electrode is driven to send out ultrasonic waves in the form of pulses, and a reflective surface formed on the other electrode allows the ultrasonic waves to propagate through the material to be welded. This reflected wave passes through the welding material again and returns to the ultrasonic transducer, which is detected during ultrasonic transmission, and from the change in the peak value of the detected reflected wave, the welding material is detected. This system is designed to determine the condition of the molten part (nugget) formed in the material, and it is possible to judge whether the welding condition is good or bad at the same time as welding, even though only one ultrasonic transducer is used. It is possible to make highly accurate judgments, and can have great practical effects.

[Brief explanation of drawings]

Fig. 1 shows the arrangement of electrodes, ultrasonic transducers, and materials to be welded during welding using a device to which the present invention is applied, and the progress state of ultrasonic waves. Fig. 2 shows the progress of ultrasonic waves detected by the transducer. Figure 3 is a diagram showing the relationship between welding time and the peak value of reflected wave C, and Figure 4 is a diagram showing the waveform of reflected wave C.
Fig. 5 is a diagram showing the relationship between the difference H2-H1 between the peak value R2 at the end of the energization time C and the peak value H1 at the time B and the diameter of the molten part. FIG. 6 is a front view showing the configuration of an embodiment of the device, FIG. 6 is a diagram showing the line ■-■ in FIG. 5, and FIGS. 7 and 8 are a pair of ultrasonic inspection devices for seam welding according to the present invention. FIG. 3 is a diagram showing a case where the electrode is composed of one disc-shaped electrode and a backing metal. In the figure, 13 is a transmitting/receiving device, 14.15 is a disc-shaped electrode, 17a, 17b, 17c, and 17d are ultrasonic transducers,
19 and 22 are ultrasonic reflecting surfaces, and 21 is a backing metal. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A pair of discs, one of which is provided with an ultrasonic transducer and an ultrasonic reflecting surface formed on the other, or a pair of discs and a backing metal. electrodes, a device that clamps and pressurizes the material to be welded between the pair of electrodes and applies a welding current, and drives the ultrasonic vibrator intermittently to send out ultrasonic waves in a pulsed manner. A method of seam welding characterized by comprising a transmitting/receiving device for detecting ultrasonic waves reflected from an ultrasonic reflecting surface by the ultrasonic transducer and outputting the detected waves as an electric signal, and determining whether the welding condition of the welded material is good or bad. Ultrasonic inspection equipment. 2. The ultrasonic inspection device for seam welding according to claim 1, wherein a plurality of ultrasonic transducers are arranged along the circumference of the electrode.