JP2019130541A - Welding method - Google Patents

Abstract

To provide a welding method which prevents a softening layer from being generated on a surface of a metal mold, to suppress abrasion and breakage.SOLUTION: Provided is a welding method according to an embodiment, that forms a weld zone to be processed by a metal mold of a predetermined shape according to a processing map. The welding method includes the steps of: setting an initial condition for welding; matching a cross section of the weld zone and the processing map, and setting a borderline region containing a processing borderline to become a surface of the metal mold after processing, in a calculation region; predicting occurrence of a softening layer concerning the calculation region; determining the quality of welding on the basis of an occurrence prediction result of the softening layer; and changing welding conditions in accordance with a quality determination result of the welding quality.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a welding technique for making a mold and repairing a damaged part.

  Products used for automobile bodies and the like are produced by pressing a steel plate using a press die. Further, casting products such as engine blocks are produced by casting using a mold. Since a mold such as a press mold or a mold is used continuously for a long time, wear or breakage may occur on the molding surface, particularly on a high load portion such as an edge portion or a strong pressure portion. When wear or breakage occurs on the molding surface of the mold, the surface is scratched and the quality of the product is degraded.

  Therefore, Patent Document 1 proposes a method for manufacturing a press die in which a high-load portion has a predetermined hardness. In this manufacturing method, a welding material for base treatment is welded to a high-load portion of a formed part made of an iron-based material, and build-up welding is performed thereon with a build-up welding material made of high-speed steel, and the build-up part is predetermined. The shape is processed.

JP 2014-208363 A

  In order to reduce the cost of a mold, a technique for repairing and repairing a damaged portion of the mold by welding is known. In the repair of the mold, the welded material is welded and welded to the repaired portion to form a welded portion, and then machined to cut into the original shape. However, welding has a problem that a softened layer is generated in a HAZ (Heat Affected Zone). If a softened layer of the welded portion appears on the surface of the mold after machining, there is a possibility that it becomes a new cause of wear and breakage of the mold after repair. Similarly, when a new mold is created using a welding technique, there is a concern about problems due to the appearance of a softened layer on the mold surface.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a welding method capable of preventing the occurrence of a softened layer on the surface of a mold and suppressing wear and breakage. Is to provide.

  A welding method according to an aspect of the present invention is a welding method for forming a welded portion that is processed into a mold having a predetermined shape according to a processing map, the step of setting initial conditions for welding, and a cross section of the welded portion. Matching the processing map, setting a boundary region including a processing boundary line that becomes the surface of the mold after processing as a calculation region, predicting generation of a softened layer in the calculation region, and the softening layer And a step of determining whether or not the welding quality is good based on the prediction result of the occurrence of welding, and a step of changing the welding conditions based on the result of the quality judgment of the welding quality.

  According to the present invention, it is possible to prevent the softening layer from being generated on the surface of the mold, and to suppress wear and breakage.

It is a flowchart which shows the welding method which concerns on embodiment. It is a flowchart which shows the calculation area | region determination process of FIG. It is a figure explaining the method of determining a calculation area | region. It is a figure explaining the method of determining a calculation area | region. It is a figure which shows an example of a structure of the metal mold | die in which a welding part is formed with the welding method which concerns on embodiment. It is a figure which shows the VI-VI cross section of FIG. It is a figure explaining the state which matched the cross section of the welding part, and the process map.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Equivalent components in each drawing are denoted by the same reference numerals, and redundant description is omitted.

  The present invention relates to a welding method for forming a welded portion that is processed into a mold having a predetermined shape according to a processing map. In the welding method according to the embodiment, for example, a welding material is welded to a damaged part of a mold to form a welded part, or a welded part is formed when a new mold is created. When repairing a mold, a welded material is formed on the damaged part of the mold that has been worn or damaged to form a welded part, and the welded part is processed and repaired according to a processing map. When repairing a damaged part of a mold by TIG welding, there is a problem that heat affected zone (Heat Affected Zone: HAZ) is softened because TIG welding has a large heat input.

  On the other hand, in laser clad welding, since it is easy to control the total amount of heat and the melting point, it is considered that the generation of the softened layer can be reduced as compared with TIG welding, but it is difficult to eliminate the generation of the softened layer itself. The softened layer is similarly generated in the welded portion for creating a new mold. Therefore, in the embodiment, by considering the shape of the mold after processing and predicting the generation position of the softened layer and determining the welding conditions, it is possible to prevent the softened layer from being generated on the surface of the mold, Suppresses wear and damage.

  FIG. 1 is a flowchart for explaining a welding method according to an embodiment. FIG. 1 shows a method for determining welding conditions. FIG. 2 shows the calculation area determination step (S2) of FIG. In FIGS. 1 and 2, for convenience, the method for determining the welding conditions is illustrated using a flowchart, but the process / procedure as a “method” is shown, and welding is performed on the damaged portion of the mold. Whether or not the welding apparatus is automatically controlled is not limited.

  With reference to FIG. 1, the overall flow of a method for determining the welding conditions of a mold will be described. As shown in FIG. 1, first, welding conditions are initially set (S1). In the initial setting of the welding conditions, for example, known or standard welding conditions such as conventional values, experience values, know-how values, experimental values, simulation values, and the like are set. In the case of laser clad welding, laser output, scanning position / pattern, material supply amount / speed, etc. are set.

  Next, a calculation area that is a target for which the occurrence of the softened layer is predicted is determined (S2). The calculation area is determined in consideration of the shape of the mold after processing. The calculation area determination method will be described later in detail. And generation | occurrence | production of a softening layer is estimated about the calculation area | region determined by S2 (S3). The generation prediction of the softened layer includes, for example, prediction of the material and generation region of the softened layer. The material of the softened layer can be predicted by, for example, a method described in Japanese Patent Application Laid-Open No. 2004-4034.

  Thereafter, whether the weld quality of the welded portion is good or not is determined based on the predicted generation of the softened layer obtained in S3 (S4). The quality of the welding quality is judged by the presence or absence of the occurrence of a softened layer at the location that becomes the mold surface after processing. If the occurrence of a softened layer is observed at a location on the mold surface after processing, it is determined that the welding quality is NG.

  When there is no problem in the welding quality (S4, YES), the welding condition determination method ends, and the initial condition set in S1 becomes the condition for welding performed on the damaged portion of the mold thereafter. On the other hand, when there is a problem in the welding quality (S4, NO), the initial conditions set in S1 are changed so as to suppress the generation of the softened layer (S5). For example, in laser clad welding, in order to suppress the generation of a softened layer, the time during which the powder material is in a molten state can be reduced and the cooling rate of the molten region can be increased. For this purpose, it is possible to change welding conditions such as “narrowing the laser irradiation diameter” and “increasing the scanning speed”.

  Here, FIG. 2 and the calculation region determining step will be described in detail. As shown in FIG. 2, the calculation region determination step includes determination of the thermal energy stable region (S 21), determination of the hardening region (S 22), and matching between the cross-sectional shape of the welded portion and the processing map (S 23). . In FIG. 2, it is described that each process is executed in the order of S21 to S23. However, these processes may be executed from any of them and may be executed simultaneously.

  Since it takes a very long time to verify / calculate the generation prediction of the softened layer one by one in all regions and feed back to the welding conditions, in the embodiment, the region in which the calculation is performed is limited (S21 to 23). In S4, in order to determine whether or not the softened layer appears on the surface of the mold when the welded portion is processed, the softened layer in the region including the processing boundary line that becomes the surface of the mold after processing is determined. Occurrence prediction is necessary. Therefore, in S23, a region including a processing boundary line that becomes the surface of the mold after processing is determined as a calculation region.

  First, determination of the thermal energy stable region (S21) will be described with reference to FIG. FIG. 3 shows a cross-section at a position where the heat input amount of the welded portion is maximized. When welding is performed on the base material 10, the temperature continuously changes from a region heated from the melting boundary toward the base material 10 to a temperature close to the melting point of the material to a region hardly affected by heat. A place where a change occurs in the microstructure in this region is referred to as a heat affected zone 11. The welded portion 13 includes a weld metal (melted region) 12 that has been melted and solidified, and a heat-affected zone 11 in which a structural change has occurred due to heat of welding. The weld metal 12 has a composition in which the weld material and the base material 10 are mixed.

  As shown in FIG. 3, the base material 10 is formed with a welded portion 13 in which a weld metal 12 is built up. A region in contact with the weld metal 12 of the base material 10 becomes the heat affected zone 11. In laser clad welding, the thermal energy of the laser becomes unstable immediately after the start and immediately before the end of welding. For this reason, in the welded portion 13 formed on the base material 10, the region immediately after the start of welding and the region immediately before the end are set as the excluded region 14 that is excluded from the calculation region for the prediction of occurrence of the softened layer, and the stable region 15 in which the thermal energy is stabilized. The calculation area.

  Next, determination of the curing region will be described with reference to FIG. In general, the softened layer 11 a is formed on the heat affected zone 11 of the base material 10. Therefore, the melting region made of the weld metal 12 in the welded portion 13 is excluded from the calculation region in which the generation prediction of the softened layer is performed. Further, as shown in FIG. 5, in laser cladding welding or the like, the melting region becomes a high temperature of about 1500 ° C., so that the heat affected zone 11 has a two-layer structure of a softened layer 11a and a hardened region 11b due to a quenching effect. Accordingly, the hardened region 11b of the welded portion 13 is also excluded from the calculation region in which the occurrence of the softened layer is predicted.

  Finally, matching (S23) between the cross-sectional shape of the welded portion and the processing map will be described with reference to FIGS. Drawing 5 is a figure showing an example of composition of metallic mold 1 in which a welding part is formed by a welding method concerning an embodiment. 6 shows a VI-VI cross section of FIG. The VI-VI cross section is in the XZ plane in the XYZ orthogonal coordinate system of FIG. Here, an example in which the damaged portion 2 is formed in the mold 1 and the welded portion is formed in the damaged portion 2 by the welding method according to the embodiment will be described. In FIG. 6, the damaged part 2 of the mold 1 is a repaired part. Repairing the mold 1 by shaping the welded portion 13 to the original shape by forming the welded portion 13 by overlay welding the damaged material to the damaged portion 2 and cutting the welded portion 13 according to the processing information (processing map). Is done. The processing map is created from CAD / CAM data of the mold 1.

  FIG. 7 is a diagram for explaining a state in which the cross section of the welded portion 13 and the processing map are matched. In FIG. 7, the cross section of the welded portion 13 is divided into 72 regions of a to l columns in the horizontal direction and 1 to 6 rows in the vertical direction. The processing boundary line 3 becomes the surface of the mold 1 after processing. If the softened layer 11a of the welded part 13 appears on the surface of the mold 1 after processing, it may become a new cause of wear and damage of the mold 1 after repair.

  Therefore, the cross section of the welded portion 13 (filled location) is matched with the processing map, and the boundary region including the processing boundary line 3 that becomes the surface of the mold 1 after processing is set as the calculation region for predicting the occurrence of the softened layer. To do. In the example shown in FIG. 7, among the divided areas, a column 6 rows, b column 6 rows, c column 5 rows, d column 5 rows, e column 4 rows, f column 4 rows through which the machining boundary line 3 passes. It is an area and a boundary area of g column 4 rows, h column 4 rows, i column 4 rows, j column 4 rows, k column 3 rows, l column 2 rows, l column 1 row.

  Moreover, the part removed by the said process among the welding parts 13 does not need to perform generation | occurrence | production prediction of a softening layer. Therefore, the removal region 4 to be removed by processing is specified as a region that does not require verification / calculation, and is excluded from the computation region. In FIG. 7, the area above the machining boundary 3 is excluded from the calculation area as the removal area 4. The removal region 4 is c column 6 row, d column 6 row, e column 5-6 row, f column 5-6 row, g column 5-6 row, h column 5-6 row, i column 5-6 row, It becomes j column 5-6 row, k column 4-6 row, l column 3-6 row.

  Thus, according to the welding method according to the embodiment, it is possible to determine the welding condition by predicting the generation position of the softened layer in consideration of the shape of the mold after processing. Thereby, it is possible to prevent the softened layer from being generated on the surface of the mold after processing, and to suppress wear / breakage. Further, by limiting the calculation area in which the generation prediction of the softened layer is limited, the calculation amount of the generation prediction of the softened layer can be reduced, and the time required for verification / calculation can be reduced.

  As described above, the quality determination of the welding quality in S4 is determined as a non-defective product when a softened layer does not appear at a location that becomes the surface of the mold 1 after processing. That is, the presence or absence of the softening layer expected in S3 is specified along the processing boundary 3 shown in FIG. For example, when the generation of the softened layer is recognized in the region of FIG. 7d column 5 rows, the welding conditions for the entire 5th row are changed in S5. If the control accuracy of the welder is improved, it is possible to change the welding conditions only in the predicted softened layer generation region.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Metal mold | die 2 Damaged part 3 Process boundary line 4 Removal area | region 10 Base material 11 Heat affected zone 12 Weld metal 13 Welded zone 14 Exclusion zone 15 Stable zone 11a Softening layer 11b Hardening zone

Claims (1)

A welding method for forming a welded portion to be processed into a mold having a predetermined shape according to a processing map,
A process for setting initial welding conditions;
Matching the cross section of the weld and the processing map, and setting a boundary region including a processing boundary line to be the surface of the mold after processing as a calculation region;
Predicting the occurrence of a softened layer for the computation region;
A step of determining whether the welding quality is good or not based on the predicted generation result of the softened layer;
Based on the quality determination result of the welding quality, changing the welding conditions;
Having
Welding method.

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