SU1433690A1 - Method of checking the penetration canal in electron-beam welding - Google Patents

Abstract

The invention relates to electron beam welding, in particular to methods of controlling the process of forming a weld, and can be used to control the welding process. The purpose of the invention is to increase the informativeness of the control when welding with a scanning electron beam by obtaining data on the topography of the channel of penetration. In order to obtain information about the topography of the channel of penetration, a data file is formed in which each position of the electron beam on the scanning trajectory is correlated with the depth of the electron beam into the material being welded. The data array allows you to determine the topography of the penetration channel and build its axonometric image. The method of control of the penetration channel can be used when selecting the shapes of the scanning path and the welding mode MOB to obtain high-quality welds with the required penetration depth. 1 hp, f-ly,. 1 il. (L

Description

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; The invention relates to electron-beam welding, in particular to methods of observing the process of forming a weld, and can be used to control the welding process.

 The purpose of the invention is to increase the informativity of the control when welding with a scanning electron beam by obtaining data on the topography of the penetration channel,

The method of controlling the penetration channel during electron beam welding by a scanning electron beam consists in forming a data array by measuring at each position of the electron beam on the scanning trajectory of two scanning coordinates and the depth of the electron beam in the material being welded. An axon metric image of the penetration channel is obtained from the formed data array.

The drawing shows the scheme of the method.

The electron beam gun 1 guides the welding electron beam 3 to the product 2 to be welded. Using the scan generator 4 and the clone systems 5 and 6, the electron beam is scanned in a plane with the X and Y coordinate axes and 11 U y are proportional to the position of the beam in the corresponding coordinates. : When welding, a penetration channel is formed in the product, which represents the special vapor-gas cavity. Geometry-: the shape and size of the penetration channel depend on the parameters of the welding process, the scan shape; electron beam, the distribution of: energy along the scanning trajectory,: the material being welded, hydrodynamic and gas in the processes in the weld pool. The topography of the penetration channel carries information about the process of the formation of welded gava. The determination of the amount of penetration of the electron beam into the material being welded is carried out by measuring the intensity of the x-ray radiation of the penetration channel with the help of the x-ray detector 7 and the measuring signal processing device 8.

The x-ray source is distributed over the channel surface.

melting. In this case, a significant part of the radiation comes from the bottom of the channel, the position of which determines the depth of penetration. X-rays are attenuated by a layer of non-molten metal according to the following law.

I i.e,

where i

P i

- intensity of the radiation source;

-.linear attenuation coefficient;

-the thickness of the layer of non-melted material.

Using the above expression and measuring the X-ray intensity, it is possible to calculate the amount of electron beam penetration into the material being welded in accordance with the expression

Z d

.- - ъ

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where d is the thickness of the product to be welded.

The conversion of the detector signal into the amount of electron beam penetration into the material being welded is performed by the measurement signal processing device 8. In order to obtain information on the topography of the penetration channel during welding by a scanning electron beam, an array of data is formed in which each position of the electron beam on the scanning trajectory is matched by the amount of depth of the electron beam in the material to be welded. This is achieved by the fact that at each position of the beam on the scanning trajectory, two coordinates Uj and Uy of the position of the beam in the scanning plane and the depth of the electron beam into the material being welded Z are measured.

The data array allows to determine the topography of the penetration channel, in particular, to construct its axonometric image. An array of data on the topography of the penetration channel can be entered into a computer for the purpose of further processing and controlling the process of electron beam welding.

The construction of an axonometric image of the perforation channel is carried out as follows. The and, and, U-2 signals are received by the three-dimensional transformation facility 9, two outputs of which are connected to the coordinate inputs X and Y of the video monitor 10. In the three-dimensional conversion device, the input signals are output to the output in accordance with the following expressions

k, and,

where K ,, Kg, K ..

X - K, Uy, Y + K4U, y

K,

K j. - scale image coefficients By changing the scale factors K.- K, you can transform the axonometric image according to the corresponding coordinates. In this case, both the scale of the image and the direction of the axes of the image can be changed.

When building an axonometric image, three coordinates of the bottom of the melting channel are used. Two of these coordinates correspond to the position of the beam on the scanning plane, and the third coordinate is the depth of the electron beam into the product being welded. This depth is calculated by a fast-acting signal processing device 8, made, for example, in the form of a logarithmic amplifier, according to the signal of the X-ray detector 7. The detector 7 is small and can be considered as a point detector. The distance from the detector 7 to the product to be welded is chosen to be significantly larger than the thickness of the product to be welded.

The image of the penetration channel can be constructed using the obtained data set on various plotters, graphic terminals.

The image on the screen of a video monitoring device is constructed as a three-dimensional image of a three-dimensional body on a plane. For this purpose, a three-dimensional conversion device 9 is used, the outputs of which receive two coordinates of the scanning of the electron beam and the coordinate of the depth of the electron beam into the material being welded,

On the screen of a video monitor, for which, for example, a cathode-ray tube can be used, an image of a channel is shown

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three coordinates X, Y, Z, and in the plane of coordinates X, Y occurs synchronously, with a welding beam, a scanning of the light spot, describing the axonometric scan image of the welding electron beam.

The Z coordinate of the image is formed by the signal about the penetration of the electron beam into the material U being welded. In this case, the light beam of the video monitor will move across the bottom of the image of the melting channel. The image of only the bottom of the penetration channel is not obvious, since at each point it is difficult to select the depth of the beam, therefore it is also advisable to obtain an image of the base of the penetration channel. For this purpose, a switch 11 is used, which periodically interrupts the signal from u2 to the video monitor and makes it equal to zero. In this case, the axonometric image outlines both the base of the penetration channel and its bottom,

The switching frequency of switch 1 must be high enough so that at each point in the image the depth signal receives a value equal to UjiH and a value equal to zero.

If the welding process is carried out without scanning the electron beam, then on the screen of the video monitoring device you will see an image of two luminous points, one of which is fixed, corresponds to the base of the melting channel, and the other to the bottom of the melting channel. The distance between the points characterizes the penetration channel penetration into the material being welded.

The tests are carried out with a control device made in the form of an electron beam functional scanning unit, a penetration meter with an x-ray sensor located on the reverse side of the welded joint, a three-dimensional conversion device with a switch, a video control device (oscilloscope),

The welding is performed in an ELU-9B installation, with a U 250 AM power source and a CEP-2M-1 welding electron gun on AMgb alloy samples with dimensions of mm. Block function

national scanning moves the electron beam along | A group of trajectories containing 6A discrete points. The scan frequency is measured in the range of 0 t 100 Hz to 2 kHz. A scintillation sensor with a BDS-6 photomultiplier tube is used as an X-ray detector. The sensor is placed 150 mm from the pairing product.

 Welding is performed on the following: modes: accelerating voltage vct - 25 kV; welding current Ter 0–70 ma; welding speed V (-g 35 m / h; measures of beam scanning across the joint Ay 0–2 mm; along joint A, 0–8 mm; scanning frequency f - 100–2000 Hz.

As a result of the tests on the oscilloscope screen, a clear image of a part of the penetration channel on the scanning contour is observed. There are changes in the depth of penetration along the scanning ontur, as well as general oscillations of the bottom of the penetration channel, into the hydrodynamic processes in the weld pool. When itfeaeHHH is in the form of a scanning trajectory, a change in the shape of the karaal is observed.

I By changing the scale coefficients of the three-dimensional transformation device: images of channel 1 | trophide in longitudinal and transverse cross sections were obtained.

I As a result of tests established by ijio, the prop channel control method can be used to select the shape and size of the trajectory ||, cannons and welding modes for producing quality welded joints with the required penetration depth, as well as for research hydrodynamic phenomena in welding Shanne.

In connection with the placement of the sensor on the back side of the welded joint, limitations are imposed on

measures of the paired product, which allows the method to be used both for research purposes and for control and management under production conditions.

The method allows real-time monitoring of the penetration channel topography. In this case, rapid changes associated with the hydrodynamic processes of the weld pool are recorded.

Claims (2)

1. A method for monitoring the penetration channel in electron beam welding, which measures the X-ray intensity from the opposite side of the beam to the side of the product being welded, processes the measurement signal to determine the amount of penetration of the electron beam into the material being welded, characterized in that, in order to increase the information content control when welding by scanning electron beam by obtaining data on the topography of the penetration channel, form an array of data measured in each position of the electron beam On the scanning path, two coordinates, scans and the amount of electron beam penetration into the material to be welded, and an axonometric image of the melting channel is formed from the data set formed. 2. The method according to claim 1, which is different from the fact that, in order to obtain an axonometric image of the penetration channel on the screen of the video monitor, a movement of the video monitor set is synchronous with the welding beam 0 five Two image coordinates, and the signal about the penetration of the electron beam into the material being welded, form the third image coordinate.