RU2550979C2 - Weld surface quality control procedure - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to welding and can be used for measuring control over weld quality, evaluation of welder qualification and weld material quality. Proposed procedure comprises measurement of weld geometrical sizes with the help of pattern and their comparison with sides set by standing specifications. Measurement results are used to calculate cross-section area of the weld. Sizes set by standing specifications are used to calculate cross-section area of the weld pattern. Now, said areas are compared to calculate the weld surface quality index.

EFFECT: high precision of weld surface quality.

2 cl, 2 tbl

Description

The invention relates to the field of welding and can be used to visually measure the quality control of welds obtained by surfacing, soldering or any known welding method, during the formation of which there is a liquid phase of the weld material, crystallizing in the field of gravity, when assessing the qualifications of welders, quality assessment of welding consumables.

A known method of quality control of welded butt joints (see Belchuk G.A. Welded joints in hull structures. - L .: Sudostroenie, 1969, p. 89-99), which is carried out by measuring the geometric parameters of the welds to determine their compliance with GOST 5264 -80. The disadvantage of this method is that in the control process only the height and width of the weld are measured, however, the strength characteristics of the welded joints are influenced by both the radius and the angle of transition from the deposited metal to the base. In addition, in the control process by this method it is impossible to quantify the quality of the surface of the weld and its deviation from the geometric center of the axis of the weld

A known method of controlling a weld by measuring with a template the geometric dimensions of the welds of the joints (RF patent No. 2032140, IPC G01B 3/14, 03/27/1995) and subsequent evaluation of the quality of the weld by comparing the data obtained with the dimensions established by the normative and technical documents. This template allows you to measure the leg of the weld, the width and length of the weld, the angle of inclination of the weld. The disadvantage of this method is that in the control process it is impossible to quantify the quality of the surface of the weld and its deviation from the geometric center of the axis of the weld.

A known method of controlling a weld (RF patent No. 2194601, IPC V23K 26/02, 20.12.2002), in which the registration of defects is carried out by continuously reading the height of the weld along the butt joint. The disadvantage of this method is that in the control process only the height of the weld is measured and only by this parameter, although continuously measured along the entire length of the weld, the quality of the weld is evaluated, and other geometric parameters of the weld are not taken into account.

The closest in technical essence to the claimed solution is a method for evaluating welded butt joints, described in RF patent No. 2205366 for the invention "Device for monitoring the geometric parameters of welded butt joints", IPC G01B 17/00, 05/27/2003.

In the specified invention, the assessment of the quality of the weld occurs by comparing the measured geometric dimensions of the weld, namely the width, height and radius of the transition with the standard. Evaluation is carried out using a device that includes a template that sets the geometric parameters of the seam in accordance with the requirements of regulatory documentation. This template is made in the form of an electrical circuit. As a measuring element, there is a box made of ferromagnetic material with an excitation winding, measuring and mounting vibration transducers. By changing the density of the magnetic fluid poured into the box, fix the change in the geometric dimensions of the weld. A means of measuring the deviation of the parameters of the controlled seam from the set is made in the form of an electronic circuit. On the screen of a two-beam oscillographic tube, the deviations of the measured geometric dimensions of the weld from the standard are observed visually.

The specified invention describes a method for measuring specific geometric parameters of welds (height, width, radius of transition from the weld metal to the base). However, this method according to the measured geometric parameters of the weld (width, height, transition radius) does not allow to quantify the quality of the weld, since it does not provide quantitative evaluation criteria. In addition, the prototype method does not allow to take into account the change in the shape of the weld surface caused by the presence of defects, such as surface pores, fistulas, surface cracks, undercuts, deviations and distortions of the axis of the weld from its geometric center, etc.

An object of the present invention is to provide a method for quantitatively controlling the quality of a weld surface in a convex shape.

The technical result is achieved due to the fact that in the proposed method for determining the quality of the weld by measuring the geometric dimensions of the weld, the cross-sectional areas of the weld are calculated. According to the given dimensions, the shape of the weld standard and the cross-sectional area of the weld standard are calculated. By comparing the absolute values of the deviation of the cross-sectional areas of the weld from the area of the standard determine the quality index of the weld.

The above methods for controlling the quality of the surface of the weld do not allow one to determine how distorted in comparison with the standard the shape of the controlled weld is due to defects (surface pores, fistulas on the surface, cracks, undercuts, bending of the axis of the weld from the center, etc. ) The shape of the standard in the prototype is set in the form of an electronic circuit based only on the geometric dimensions established by the regulatory documentation and does not take into account the surface tension of the molten weld metal acting in the field of gravity. The angle between the perpendicular section to the weld and the horizontal plane of the weld is not taken into account either. In the inventive method, all these parameters are taken into account.

1. Achieving quantitative quality control of the surface of the weld consists in determining the quality index of the weld, determined from the following ratio:

Where

Q - weld quality index,%;

N = L / dL + 1 - the number of measured sections of the weld with a measurement step of dL greater than or equal to 0.01 mm;

L is the length of the weld, mm;

j is the current value of the area of the measured section of the weld;

- абсолютное отклонение площади j-го сечения сварного шва от площади сечения эталонного сварного шва; $$S_j^{\mathrm{ABOUT}T\mathrm{TO}L}$$

- the absolute deviation of the area of the j-th section of the weld from the cross-sectional area of the reference weld;

;

;

B is the measurement width in the range from 1.1 e to 10 e;

e is the width of the specified reference weld, mm;

- измеренные значения координат поверхности сварного шва с шагом dx от 0,01 мм до 2 мм; $$Z_j^F(x)$$

- measured values of the coordinates of the surface of the weld with a step dx from 0.01 mm to 2 mm;

Z, x are the coordinates of the curve in the coordinate system Z0X;

Z ^E (x) - a curve that determines the shape of the reference weld;

S ^E - the cross-sectional area of the reference weld.

2. The method according to claim 1, characterized in that the shape of the reference weld is determined by the specified dimensions of the weld from the following ratio:

Where

Z = Z (x) - curve, for given values of a _k , e, g, φ determines the shape of the curve of the reference weld Z ^E (x);

and _k is the capillary constant of the molten material of the weld, mm;

g is the height of the reference weld, mm;

φ is the angle between the plane perpendicular to the axis of the weld in the coordinate system Z0X and the horizon line;

R ₀ is the radius of curvature of the curve Z = Z (x) at x equal to 0; wherein the cross-sectional area of the reference weld is determined in the range of values from x greater than or equal to 0 to x less than or equal to "e" and the following formula:

The invention is illustrated by the following example.

Example

The quality of five samples of welded joints made in accordance with the flow chart for hazardous technical devices (hoisting-and-transport equipment, the standards of defectiveness for which are established in the normative and technical documentation RD 03-606-03 and RD 22-326-97) were determined along the length seam 400 mm. Welded joints were made in accordance with the requirements of GOST 14771-76 from 10 mm thick plates from 09G2S mild steel by semi-automatic welding in a carbon dioxide medium with steel wire of 08G2S grade 1.2 mm in diameter. The weld is made in the lower position, for which the angle φ is 0 degrees.

In accordance with the requirements of GOST 14771-76, these welded joints have the symbol C21, for which the following standard dimensions of the weld are established:

The width of the weld e is equal to 14 mm;

The height of the weld g is 1 mm.

For this type of wire, the value of the capillary constant a _{k is} taken equal to 4.9 mm [B. Berezovsky Mathematical models of arc welding T. 1. Mathematical models of arc welding. - Chelyabinsk: Publishing house of SUSU, 2002. - 586 p.].

. Полученные в каждом сечении значения, заносили в память компьютера.Surface scanning of all five welded joints was performed by a 2D triangulation laser scanner. Scanning of the surface of welded joints was carried out at a length of 400 mm in cross sections at a measurement width of V mm. In this case, with a step of dx mm, the surface of the first section was first scanned, then the laser beam was moved along the axis of the seam with a step of dL mm and the surface of the second section was scanned, after which the laser beam was again moved along the axis of the seam by one step and the next section was scanned. Scanning the surface of subsequent sections and beam movements is carried out similarly. In each section, the coordinates of the points of the surface, described in the coordinate system as a function, were measured $$Z=Z_j^F(x_i)$$

. The values obtained in each section were entered into the computer memory.

The shape of the weld standard, Z ^E (x), was determined by numerically solving the equation $$\frac{Z\text{'}\text{'}\text{'}\text{'}(x)}{{(\mathrm{one}+{(Z\text{'}\text{'}(x))}^2)}^{\frac{3}{2}}}-\frac{Sin\varphi }{a_K^2}x-\frac{Cos\varphi }{a_K^2}Z(x)+\frac{\mathrm{one}}{R_0}=0$$

With the value of the angle φ = 0 °, the equation of the form of the virtual standard takes the following form:

Given standard values of weld width e equal to 14 mm specified by GOST 14771-76 and weld height g equal to 1 mm, surface tension coefficient for steel a _k equal to 4.9 mm [B. Berezovsky Mathematical models of arc welding, t. 1. Mathematical models of arc welding. - Chelyabinsk: SUSU Publishing House, 2002. - 586 p.], The radius of curvature R _{0 of the} function Z ^E (x) at a point x equal to 0, determined in the process of solving the above equation, by the sweep method [Computational methods of applied boundary value problems. - M. Mir, 1982. - 294 p.] Calculated the shape of the standard of the weld Z ^E (x). The calculated values are given in table. 1. Based on the data of table 1 by the trapezium method [Piskunov N.S. Differential and integral calculus for technical colleges: in 2 volumes T. 1. Textbook for technical colleges. - M .: Science. The main edition of the physical and mathematical literature, 1985. - 432 p.], According to the formula:

вычисляли площадь эталона сварного шва S^Э.

calculated the area of the standard of the weld S ^E.

By comparing the area of each cross section, the controlled seam with the area of the standard of the weld, the deviation area was determined.

The calculation of the quality index of the facing seam was performed according to the formula:

The values of the initial parameters of all examined five welds and their quality index are given in table. 1. In the table. 2 shows the regulatory requirements for quality control of the surface of the weld and assessment of the quality of the surface of the weld according to the prototype and the claimed method.

Thus, the above information indicates that when using the claimed invention, the necessary combination of conditions:

the method embodying the claimed invention in its implementation, allows to quantify the surface quality of the weld according to the shape of the bulge.

for the claimed invention in the form described in the claims, the possibility of its implementation using the methods and methods described above or known prior to the priority date is confirmed;

means embodying the claimed invention in its implementation, is able to ensure the achievement of the perceived by the applicant technical result.

Therefore, the claimed invention meets the requirement of "industrial applicability" under applicable law.

Claims (2)

1. A method of controlling the quality of the surface of the weld, including measuring the geometric dimensions of the weld using a template and comparing them with the specified dimensions of the reference weld, characterized in that according to the results of measuring the geometric dimensions of the weld, the cross-sectional areas of the weld are calculated from the given sizes of the reference weld the seam determine its shape and calculate the cross-sectional area of the reference weld, while the quality of the surface of the weld is judged by the quality index of the surface of the weld Q which is determined from the following ratio:

Where
Q - weld quality index,%;
N = L / dL + 1 - the number of measured weld sections with a measurement step dL greater than or equal to 0.01 mm;
L is the length of the weld, mm;
j is the current value of the area of the measured section of the weld;

- the absolute deviation of the area of the j-th section of the weld from the cross-sectional area of the reference weld;

In - the width of the measurement in the range from 1.1 e to 10 e;
e is the width of the specified reference weld, mm;

- measured values of the coordinates of the surface of the weld with a step dx from 0.01 mm to 2 mm;
Z, x are the coordinates of the curve in the coordinate system Z0X;
Z ^E (x) - a curve that determines the shape of the reference weld;
S ^E - the cross-sectional area of the reference weld. 2. The method according to claim 1, characterized in that the shape of the reference weld is determined by the specified dimensions of the weld from the following ratio:

Where
Z = Z (x) - curve defining at given values a _to e, g, φ form a reference weld Z curve ^E (x);
and _k is the capillary constant of the molten material of the weld, mm;
g is the height of the reference weld, mm;
φ is the angle between the plane perpendicular to the axis of the weld in the coordinate system Z0X and the horizon line;
R ₀ is the radius of curvature of the curve Z = Z (x) at x equal to 0;
wherein the cross-sectional area of the reference weld is determined in the range of values from x greater than or equal to 0 to x less than or equal to "e" and the following formula:

.