JP6447220B2 - Shape detection method for overlay welding - Google Patents

Description

  The present invention relates to a shape detection method for overlay welding, and particularly to a shape detection method useful for determining a welding target position when overlay welding is performed on the surface of a cooling wall panel.

  A water-cooled wall panel as a cooling wall panel in a boiler or the like has a large number of cooling water pipes that are refrigerant pipes arranged in parallel, and the opposite side surfaces of adjacent cooling water pipes are connected by fillet welding to both side edges of the plate fins. It has a structure. The surface of such a water-cooled wall panel facing the inside of the furnace is covered by overlay welding with stainless steel, nickel-base alloy or the like in order to prevent corrosion thinning. In general, in order to automate build-up welding, for example, in Patent Document 1, the target position is adjusted with a teach pendant, and then the welding manipulator is moved and controlled based on the applied voltage detected by the arc sensor unit.

JP2011-251289A

  However, since the water-cooled wall panel has a relatively complicated shape and a large individual difference, and also causes deformation during welding, the conventional overlay welding method adjusts the welding target position in advance and applies applied voltage. However, there is a problem that proper automatic welding is difficult even when the position of the vertical welding torch is adjusted to the welded portion.

  Accordingly, the present invention solves such problems and provides a method for detecting the shape of a build-up welding target that is useful when performing build-up welding of a cooling wall panel having a relatively complicated shape and large shape change. The purpose is to do.

  In order to achieve the above object, according to the first aspect of the present invention, fillet welding (3) is performed on adjacent side surfaces of a plurality of refrigerant pipes (1) arranged side by side on both side edges of a flat fin (2). When the surface of the cooling wall panel (P) is build-up welded, the connecting portion of the fin (2) is connected from one top surface of the adjacent refrigerant pipe (1). Then, the surface shape reaching the other top surface of the refrigerant pipe (1) is detected, and the approximate circle (SC, SC ′) is detected for the portion following the outer periphery of each refrigerant pipe (1) in the detected surface shape. The apex of these approximate circles is determined as the top inflection point (C, C ′), and the fillet weld (3) is the point where the amount of change in the difference between the approximate circle and the surface shape exceeds a predetermined value. And the predetermined value from the approximate straight line (SL) of the fin (2). Ete other side edge inflection point of the fillet weld points spaced (3) (B, B') and determined.

  In the first aspect of the invention, since the top surface inflection point and the fillet welding one and the other side edge inflection points can be accurately determined for the adjacent refrigerant pipes, the displacement of the welded portion and the deformation at the time of welding are determined. Even if the shape changes greatly due to, for example, automatic welding can be performed with the welding target position of overlay welding appropriately determined.

  In the second aspect of the present invention, an area in which the slope of the change in distance from the center of at least one of the approximate circles (SC, SC ′) to the surface shape among the surface shapes becomes a substantially constant value is defined as the fin. It is determined that the part is (2).

  According to the second aspect of the present invention, the approximate straight line can be created by accurately specifying the fin portion, so that the other side edge inflection point of the fillet weld can be determined more accurately.

  The reference numerals in the parentheses refer to the correspondence with specific means described in the embodiments described later.

  As described above, according to the shape detection method for build-up welding object of the present invention, automatic build-up welding of a cooling wall panel having a relatively complicated shape and a large shape change can be appropriately performed.

It is a one part perspective view of the water cooling wall panel which is a build-up welding object. It is sectional drawing of a part of water cooling wall panel. It is the figure which plotted the measurement point data of the surface shape of the water cooling wall panel which performs overlay welding. It is a figure which shows the value in each position of the difference of the distance from the center of an approximate circle to each surface measurement point, and the radius of an approximate circle. It is a figure which shows the value in each position of the first-order differential value of a difference. It is the figure which plotted the measurement point data of the fin part. It is a figure which shows the inclination of the distance change from the center of a left approximate circle to each surface measurement point. It is a figure which shows the inclination of the distance change from the center of a right approximate circle to each surface measurement point. It is the figure which plotted the data obtained by superimposing the data of FIG. 7 and FIG. It is a figure which shows the detection accuracy of a top surface inflection point. It is a figure which shows the detection accuracy of one side edge inflection point of a fillet weld part. It is a figure which shows the detection accuracy of the other side edge inflection point of a fillet weld part.

  The embodiment described below is merely an example, and various design improvements made by those skilled in the art without departing from the gist of the present invention are also included in the scope of the present invention.

  FIG. 1 shows an appearance of an example of a water-cooled wall panel as a cooling wall panel that is an object of overlay welding, and FIG. 2 shows a cross section thereof. The water cooling wall panel P has a structure in which a plurality of circular cooling water pipes 1 are arranged in parallel and these cooling water pipes 1 are connected by thick plate-like fins 2. The connection is made by continuous fillet welding (reference numeral 3 in FIG. 2) of the opposite side surfaces of the adjacent cooling water pipes 1 to both side edges of the fins 2.

  In FIG. 2, the surface of the water-cooled wall panel P covered by overlay welding (upper surface in the figure) is the surface of the cooling water pipe 1, the surface of the fillet weld 3, and the surface of the fin 2 having the groove 4. It is formed and extends in the piping direction (see FIG. 1). The recessed groove portion 4 is repeated between the cooling water pipes 1 adjacent to each other in the panel width direction (left-right direction in FIG. 1).

  When overlay welding is performed on the surface of such a water-cooled wall panel P, the top surface inflection points C and C ′ of the adjacent cooling water pipes 1 forming the cross section of the recessed groove portion 4 and the fillet weld portion 3 It is necessary to determine the positions of a total of 6 points of inflection points A, A ′, B, B ′ on both sides. That is, from these six inflection points A, A ′, B, B ′, C, C ′, for example, the welding target position of the first layer of overlay welding is set to the center position between the points BB ′, The welding target position of the second layer is set as the position of points A to A ′, and the welding target position of the nth layer is set as a position calculated from the points C to C ′ and an approximate circle described later. Therefore, it is necessary to accurately determine the inflection points A, A ′, B, B ′, C, and C ′. A procedure for determining the positions of these inflection points A to C ′ will be described below.

  First, the surface shape of the water-cooled wall panel P is measured using a laser displacement meter or the like. The obtained surface shape is the same as the panel cross-sectional shape described above, as shown in FIG. In view of the fact that the shape of the cooling water pipe 1 portion is substantially circular and stable, approximate circles SC and SC ′ are obtained from the surface measurement point data of the laser displacement meter of this portion using the least square method or the like. The apexes of the approximate circle are the top surface inflection points C and C ′ of the refrigerant pipe 1.

  One side inflection point A, A 'of the fillet weld 3 is the difference between the approximate circle SC, SC' and the surface measurement point data MD, that is, from the center of the approximate circle SC, SC 'to each surface measurement point. And the amount of change in the difference between the approximate circles SC and SC ′ radii exceeds a predetermined value. Here, FIG. 4 shows the value of the difference between the distance from the center of the approximate circle SC, SC ′ to each surface measurement point and the radius of the approximate circle SC, SC ′ at each x coordinate position of the groove 4. FIG. 5 shows what value the first differential value of the difference takes at each x-coordinate position. Then, the positions of the side edge inflection points A and A ′ are determined by setting an appropriate threshold for the first-order differential value.

  The other side edge inflection points B and B ′ of the fillet weld portion 3 coincide with this as shown in FIG. 6 by utilizing the fact that the surface measurement point data of the fin 2 portion are arranged in a substantially straight line. An approximate straight line SL is created, and points that are separated from the approximate straight line SL by a predetermined value are set as side edge inflection points B and B ′.

  Of the surface shape of the water-cooled wall panel P, the identification of the fin 2 part is performed as follows. That is, when the distances from the centers of the approximate circles SC and SC ′ to the respective surface measurement points are calculated, the gradient (first-order differential value) of the change in the calculated distance becomes a constant value as the surface shape is closer to a straight line. . Here, FIG. 7 shows the gradient of the change in distance from the center of the left approximate circle SC in FIG. 3 to each surface measurement point, and FIG. 8 shows each surface from the center of the right approximate circle SC ′ in FIG. Indicates the slope of the change in distance to the measurement point. In FIG. 7 and FIG. 8, there are two regions where the inclination of the change is almost constant, because this is because there is a straight line part in the fillet weld 3 part. Therefore, the data of FIG. 7 and FIG. 8 are overlaid to emphasize the change (FIG. 9). In this case as well, an area where the inclination of the change is almost constant is determined as the fin 2 part, and an approximate straight line is created. To do.

FIGS. 10 to 12 show the positional accuracy of the inflection points A, A ′, B, B ′, C, and C ′ determined by such a procedure for 25 different samples. According to this, all the inflection points A to C ′ are determined with sufficient accuracy within 0.5 mm. And the determination of such inflection points A to C ′ is performed at an appropriate location of each concave groove portion 4 extending along the cooling water pipe 1, so that the position of the fillet welded portion is shifted or deformed by welding. Even if there is a place, the shape to be welded can be detected accurately, and automatic welding can be performed with the welding target position appropriately determined based on this.

DESCRIPTION OF SYMBOLS 1 ... Cooling water piping (refrigerant piping), 2 ... Fin, 3 ... Fillet welding, P ... Water cooling wall panel (cooling wall panel), A, A '... One side edge inflection point, B, B' ... The other Side edge inflection points, C, C ′, top inflection points, SC, SC ′, approximate circle, SL, approximate line.

Claims (2)

A cooling wall panel formed by fillet welding adjacent side faces of a plurality of refrigerant pipes arranged side by side to both side edges of a flat fin, and adjacent to each other when overlay welding the surfaces of the cooling wall panels The surface shape from one top surface of the refrigerant pipe to the other top surface of the refrigerant pipe through the connecting portion of the fin is detected, and the portion of the detected surface shape that follows the outer periphery of each refrigerant pipe is Approximate circles are set, and the apexes of these approximate circles are determined as top inflection points, and the change in the difference between the approximate circle and the surface shape exceeds a predetermined value at one side edge change of the fillet weld. A shape detection method for overlay welding, characterized in that it is determined as a bending point, and a point separated from the approximate straight line of the fin beyond a predetermined value is determined as the other side edge inflection point of the fillet welding. 2. The meat according to claim 1, wherein an area in which a slope of a change in distance from the center of at least one of the approximate circles to the surface shape is a substantially constant value among the surface shapes is determined as the fin portion. A method for detecting the shape of a welded object.