JPH0311873B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention detects X-rays generated from the workpiece by deflecting and scanning the electron beam, thereby relatively moving the electron beam and the workpiece. The present invention relates to an automatic positioning method for an electron beam welding machine that automatically determines the position such as the center coordinates of a circular welding line.

[Prior art]

FIG. 1 is a block diagram showing a conventional automatic positioning device for an electron beam welding machine using deflection scanning of an electron beam. In the figure, 1 is an electron beam, 2 is a deflection coil, 3 is a current amplifier that drives the deflection coil 2,
4 is a signal generator for controlling the amount of deflection of the electron beam 1; 5 is the object to be welded; 6 is the welding line; and 7 is an X generated from the electron beam irradiation position on the surface of the object to be welded 6.
ray, 8 is an X that detects the X-ray 7 and converts it into an electrical signal.
ray detector; 9 is an X-ray detection device that processes the detection signal of the X-ray detector 8; 10 is a signal generator 4 signal and X-ray detector;
A signal processing and display device that processes the output signal of the line detection device 9 and displays the weld line position; 11 is a weld line detection device that is composed of an X-ray detector 8, an X-ray detection device 9, and a signal processing and display device 10; be.

The conventional automatic positioning device is configured as described above, and performs electron beam welding after positioning the workpiece by the following operations. First, a deflection current is applied to the deflection coil 2 via the signal generator 4 and the current amplifier 3,
The electron beam 1 focused on the object to be welded 5 scans the object to be welded 5 following the deflection current. During scanning, X-rays 7 generated from the irradiation position of the electron beam 1 on the workpiece 5 are detected by the X-ray detector 8 and converted into electrical signals by the X-ray detection device 9 . The converted electric signal and the current signal of the deflection coil 2 are input to the signal processing display device 10, and the deflection angle of the electron beam 1 and the intensity of the X-rays are displayed on the cathode ray tube in synchronization. FIG. 2 shows the displayed pattern.

In FIG. 2, 21 is a display signal of the electron beam 1, and 22 is an electron beam axis signal corresponding to the irradiation position on the workpiece 5 when the electron beam 1 is in a stationary state without deflection scanning. Note that the horizontal axis of the figure represents the deflection coil current, and the vertical axis represents the intensity of X-rays. The reason why the display signal 21 is attenuated in the middle in this figure is because the electron beam 1 enters the gap between the seams at the welding line 6 during scanning, and as a result, the intensity of the generated X-rays decreases. Line detector 8 and therefore X
This is because the electric signal of the line detection device 9 also becomes smaller. For positioning, the object to be welded is moved while watching the pattern on the cathode ray tube so that the welding line 6 and the electron beam axis are aligned.

Since the conventional automatic positioning device performs positioning by such an operation, in the case of a circular welding line 31 as shown in FIG. The object to be welded 5 had to be rotated while observing the pattern to align one axis of the electron beam with the circular welding line 31.

In particular, for a plurality of circular welding lines 31, the center of rotation of the workpiece 5 is moved for each circular welding line 31, and the workpiece 5 is rotated and positioned each time while looking at the pattern displayed on the cathode ray tube. There were some disadvantages, such as the need for multiple operations.

[Summary of the invention]

The present invention detects the welding line by deflecting an electron beam to scan a welding line at one location of a circular welding line, and detects the welding line by deflection current amount I10 of the electron beam when the welding line is detected.
a step of moving the detected welding line to a preset distance D in the opposite direction to the deflection direction of the electron beam; and a step of deflecting and scanning the electron beam on the welding line that has been moved to the distance D to detect the welding line. Deflection current amount I of the electron beam when the welding line is detected
11, and obtaining the angle β as the amount of change in the deflection angle of the electron beam from the deflection current amount I10 and the deflection current amount I11, and calculating the distance D and the angle β.
a step of determining the distance l between the electron beam deflection means and the workpiece based on the above, and a step of deflecting and scanning the electron beam in the X-axis direction of the circular welding line to cross between the welding lines, respectively. The amount of deflection current I1 from the electron beam axis to each welding line is detected by detecting the welding line of
I2 is determined, and the deflection angles α1, α1, in the X-axis direction are determined based on the deflection current amounts I1, I2.
The step of determining α2 is the step of scanning the electron beam deflection in the Y-axis direction of the circular weld line, and when crossing between the weld lines, detecting each weld line, and detecting the deflection current from the electron beam axis to each weld line. Determine the amounts I3 and I4, respectively, and calculate the deflection current amounts I3 and I4.
a step of determining the deflection angles α3 and α4 in the Y-axis direction based on the distance l and the deflection angles α1 and α2;
Find the distances X1 and X2 from the electron beam axis to each welding line based on the above, and find the distances Y1 and Y2 from the electron beam axis to each welding line based on the distance l and the deflection angles α3 and α4. , further calculating the center coordinates of the circular welding line from distances X1, X2 and distances Y1, Y2;
or a step of aligning the center position of the circular welding line with the electron beam axis of the electron beam, thereby making it possible to easily position even a plurality of circular welding lines. Our goal is to provide the following.

[Embodiments of the invention]

FIG. 4 shows an embodiment of the present invention. In the figure, numerals 1 to 9 are the same as the conventional device described above. However, unlike the conventional device, the deflection coils 2 are provided at four locations, front, back, left and right, in order to scan the electron beam 1 in the front, back, left and right. Corresponding to the provision of the four deflection coils 2, a deflection direction switch 47 for switching the deflection direction is provided between the current amplifier 3 and the deflection coil 2, unlike the conventional device. The X-rays generated from the workpiece 5 by the projected electron beam 1 are
The radiation is detected by the ray detector 8 and converted into an electrical signal by the X-ray detection device 9. The electric signal is transmitted to the deflection amount detection device 41
A peak value is detected by a peak detector 46 in the inner part, and a deflection current at the peak time is detected. Next, those data, that is, the distance l between the workpiece 5 and the deflection coil 2, and the amount of deflection current obtained from the deflection amount detection device 41 and the peak detector 46 are measured from the beam axis to the welding line and the circular welding line 31. The distance to the center coordinates of is input to the arithmetic unit 42 for calculation. Then, based on the calculated distance, the X-Y axis table 43 on which the workpiece 5 is placed is moved by the motor 44 via the NC control device 45 so that the center coordinates of the electron beam axis and the circular welding line coincide. let

Note that although the deflection amount detection device 41, the peak detector 46, and the calculation device 42 are shown as being provided on each axis of the X-Y axis table, they may be used in common.

The automatic positioning device configured as described above performs automatic positioning by the following operation. First, the workpiece 5 with the circular welding line 31 is placed on the X-Y axis table 43, and the irradiation position of the electron beam 1 when no deflection is applied and the center coordinates of the circular welding line 31 almost match. The workpiece 5 to be welded is set as follows. Next, the deflection direction is set in the deflection direction switch 47 so that the deflection direction of the electron beam 1 is in the X-axis direction, and as shown in FIG. The electron beam 1 is scanned so as to cross the circular welding line 31 at two locations.
At this time, the X-rays 7 generated from the workpiece 5 are reduced at the circular weld line 31. Therefore, the X-rays 7 generated from the workpiece 5 are detected by an X-ray detector 8 and an X-ray detector 9.
is detected, converted into an electrical signal, a peak detector 46 detects a decrease in the X-ray signal, and a deflection amount detection device 41 determines the amount of deflection current at that time.

Next, in order to perform the same operation in the Y-axis direction, the deflection direction switch 47 changes the deflection direction of the electron beam 1 to the Y-axis direction, and the same operation is performed. As a result, as shown in Figure 5, a total of 4
The decrease in the X-ray signal at these locations and the deflection current at that time are determined.

By the way, if the deflection current of the electron beam 1 from the approximate center coordinates of the circular welding line 31 to one point on the circular welding line 31 is _I1 and the deflection angle at that time is _α1 , then the deflection current _I1 is the deflection angle Since it is proportional to α ₁ , the relationship is shown by the following equation.

α ₁ =AI ₁ ...(1) Here, A is a constant determined by the characteristics of the device. The distance between the irradiation position of the electron beam 1 and one point on the circular welding line 31 when no deflection is applied, that is, the distance X ₁ shown in FIG. 5, is the distance between the workpiece 5 and the center of the deflection coil 2. Assuming that l is a known value, it is determined by the relationship shown in the following equation.

X ₁ = l _tao α ₁ ...(2) Similarly, as shown in Fig. 5, the circular weld line 31
The distances X ₁ , X ₂ , Y ₁ , and Y ₂ to the four points are calculated. Circular welding line 31 from distances X ₁ , X ₂ , Y ₁ , Y ₂
The center coordinates (X, Y) of can be obtained from the following equation.

_X = _{X 1 +} The center coordinates of the circular welding line 31 (X
Y) is determined, and the NC controller 45 moves the X-Y axis table via the motor 44 or moves the electron gun to match the axis of the electron beam 1 with the center coordinates of the circular welding line 31.

Generally, in the case of a circular welding line 31, the radius r is known, so if the centers are matched by automatic positioning, the X-Y axes can be moved by the radius r and welding can be performed automatically and accurately.

In the above explanation, the explanation starts from the state where the distance l between the center of the deflection coil 2 or the deflection lens and the workpiece 5 has already been calculated and determined. The method will be explained based on FIG. First, the electron beam 1 is scanned in the X-axis direction, the welding line is detected from the decrease in the X-rays 7, and the amount of deflection current _I10 of the electron beam 1 up to the welding line is determined.
Next, move the X-Y axis table 43 or the electron gun to move the welding line position in the X-axis direction by a previously known set distance D.
move only. Next, the electron beam 1 is scanned in the same X-axis direction, the welding line is detected by the same means, and the amount of deflection current I ₁₁ of the electron beam 1 up to the welding line is determined. Incidentally, the angle β, which is the amount of change in the deflection angle of the electron beam 1 caused by moving the deflection currents I ₁₀ and I ₁₁ by a previously known set distance D, can be found by the following equation.

β=A|I ₁₀ −I ₁₁ | ...(5) Here, A is a constant.

On the other hand, the angle β, the set distance D, and the distance l between the center of the deflection coil and the workpiece 5 have the following relationship.

l=D/β...(6) Therefore, by this equation (6), if β and D are known, l
is required. Therefore, the amount of deflection current I ₁₀ and
Input the data of I ₁₁ to the arithmetic unit 42, and use equation (5) and (6)
The distance l can be found by calculating based on the formula.

Based on the distance l obtained in this way, the position of the center coordinates of the circular welding line 31 described above is determined.

In the above embodiment, X-rays were used to detect welding lines, but
Irradiation of the electron beam 1 causes secondary electrons to be applied to the workpiece 5.
Since the secondary electrons are reflected from the welding line, the object of the present invention can be similarly achieved even if the secondary electrons are used for detecting the welding line. Furthermore, in the above embodiment, the movement of the X-Y axis table 5 is controlled by the NC control device 44 as a method for aligning the center of the circular welding line 31 calculated by the calculation device 42 with the axis of the electron beam 1. However, the electron beam 1 may be moved by using an NC control device to drive the X-Y moving device of the electron gun for the electron beam 1. Of course, the center of the circular welding line obtained from the arithmetic unit 42 may be displayed on a display such as a cathode ray tube, and the X-Y axis table or the electron gun of the electron beam 1 may be moved manually. Furthermore, the center coordinates of the circular welding line 31 can also be corrected by beam deflection.

〔Effect of the invention〕

As explained above, the present invention has the effect of greatly reducing the time and labor required for welding, since the center coordinates of the circular weld line are automatically and accurately determined, unlike conventional devices. Furthermore, unlike in the case of conventional devices, the coordinate positions can be continuously and automatically determined even for a plurality of circular welding lines, so welding labor and time are significantly reduced and accurate welding is possible.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a conventional automatic positioning device, Fig. 2 is a line diagram showing display signals displayed on a signal processing display device in a conventional automatic positioning device, and Fig. 3 is a welded object having a circular weld line. Fig. 4 is a configuration diagram showing an embodiment of the present invention; Fig. 5 is an explanatory diagram showing the relationship between the distance from the beam axis of the electron beam to the welding line and the deflection angle; Fig. 6 is a deflection coil. FIG. 3 is an explanatory diagram for determining the distance from to the object to be welded. In the figure, 1 is an electron beam, 2 is a deflection coil,
3 is a current amplifier, 4 is a signal generator, 5 is a workpiece to be welded, 7 is an X-ray, 8 is an X-ray detector, 9 is an X-ray detection device, 31 is a circular welding line, 41 is a deflection amount detection device,
42 is an arithmetic unit, 43 is an X-Y axis table, 44
is a motor, 45 is an NC control device, 46 is a peak detector, and 47 is a deflection direction switch. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. An automatic positioning method for an electron beam welding machine that automatically determines the position of the center coordinates of the circular welding line by deflecting and scanning the electron beam of the electron beam deflecting means onto the circular welding line of the workpiece. , a step of deflecting an electron beam to scan a welding line at one location of the circular welding line to detect the welding line, and determining an amount of deflection current I10 of the electron beam when the welding line is detected; a step of moving the electron beam to a preset distance D in the opposite direction to the deflection direction of the electron beam; detecting the welding line by deflecting the electron beam to scan the welding line that has been moved to the distance D; and detecting the welding line; determining an angle β as a change in the deflection angle of the electron beam from the deflection current amount I10 and the deflection current amount I11, and based on the distance D and the angle β. and the distance l between the electron beam deflection means and the workpiece
When the electron beam is deflected and scanned in the X-axis direction of the circular welding line and crosses between the welding lines, each welding line is detected and the amount of deflection current from the electron beam axis to each welding line is calculated. While finding I1 and I2,
a step of determining deflection angles α1 and α2 in the X-axis direction based on the deflection current amounts I1 and I2; and a step of deflecting and scanning the electron beam in the Y-axis direction of the circular welding line to cross between the welding lines, respectively. Detect the welding lines of and calculate the deflection current amounts I3 and I4 from the electron beam axis to each welding line, respectively,
a step of determining deflection angles α3, α4 in the Y-axis direction based on the deflection current amounts I3, I4; and determining distances X1, X1, from the electron beam axis to each welding line based on the distance l and the deflection angles α1, α2.
In addition to determining X2, distances Y1 and Y2 from the electron beam axis to each welding line are determined based on the distance l and the deflection angles α3 and α4, and further distances X1,
a step of determining the center coordinates of the circular welding line from A method for automatically positioning an electron beam welding line, comprising a step of aligning center positions.