KR100393891B1 - Welding method of Tailored Welded Blank using Electrode Roller System - Google Patents

Abstract

The present invention relates to a T.W.B. manufacturing method for producing a tailored blank product having excellent productivity and quality in the manufacturing process of a press working material assembled by welding a plurality of dissimilar steel sheets according to the purpose. In the laser welding of the precisely cut material according to the present invention, the allowable width can be increased up to 0.4 mm, and the quality is improved by eliminating the hardening of the weld and the productivity is improved by preheating. It can be improved compared to the existing. For this purpose, T.W.B manufacturing method using electric resistance welding roll was selected instead of the existing roller system method.

Description

Manufacturing method of tailored blank sheet using electrode roller system {Welding method of Tailored Welded Blank using Electrode Roller System}

Field of invention

According to the present invention, a tailored welded blank (TWB) plate for automobiles is used for automobile use by laser welding after cutting a press molding material having different, different materials, or different thicknesses according to the use. It relates to a manufacturing method of. In particular, the present invention relates to a method for manufacturing a tailored blank (TWB) product having excellent productivity and quality in a manufacturing process of a press-working material to be assembled after welding. In order to manufacture (Tailored Welded Blank) plate as a roller system, the roller system is provided as a non-contact roller and a welding roller, respectively, and a welding roller is usually provided as an upper / lower electrode roller having an internal water cooling device. The outer ends of both welded plates are fixed up and down with the upper platform and the support of the lower, respectively, and the edges of the welded objects are pressed and pressed on the lower electrode rollers, and then energized to the electrode rollers. a ₃ transformation point or more and then heated to the electrode roller 50 to ℃ processed hot-rolled re-positive blood welding plate Relates to a process for preparing a TWB steel sheet characterized in that the edge joint, hayeoseo welding.

This TWB steel sheet manufacturing method is already widely used as a manufacturing method for automobile press processing materials in Europe, USA and Japan, etc., and two or three lasers are cut after tailoring them for the purpose. It is made by welding by laser).

According to the related art, when laser welding a sheet having a different thickness or a different thickness, the gap between the two sheets becomes difficult or impossible, and even a sheet cut by a press or a shear is attached. As shown in the figure, most gaps occur.

Therefore, four methods have been generally used to achieve the above object.

Firstly, there is a method of minimizing welding allowable gap through welding by precision processing by mold and crop shear to enable welding to within 0.1mm. Notelfer of Thyssen Group in Germany manufactures door inners in this way and was developed by incorporating Notelfer's unique mold expertise.

However, not only the precision mold control technology, but also the welding section of the workpiece on the wear side of the mold is more easily expressed 0.1 mm more easily, so that when one side becomes 0.05 mm, the welding is impossible. After that, there is a problem such as the need to rework the die blade, and even a slight burr is a difficult manufacturing method is not allowed. However, it has the advantage of excellent productivity in manufacturing with only simple straight welding such as excellent mold technology and door inner. This is how Hyundai's T.W.B manufacturing method is introduced.

Second is the press rolling method of the welded cross section developed by Soudronic in Switzerland. This is a method of filling a gap between plates by clamping a sheet having a thin thickness and then joining a thick sheet to the thin sheet and rolling the edge of the thick sheet. In this way, the weld gap can be as high as 0.3mm even without the precision mold technology, so the stability of the quality is very high. However, due to excessive rolling of one side, the loss of productivity due to the increase of the weld hardness and the clamping process were not considered. In addition, the rolling (rolling press) has a problem that the durability of the roller is also worsened.

Third is the Precision Shearing technology from Bill, USA. In this technology, the edge of the plate to be welded is cut by the precision shearing machine, and the welding is performed. In this process, the gap between the welding sections is adjusted to within 0.07mm and the equipment is very simple. The loss of productivity is considered to be as much as cutting at the shearing machine and the addition of a continuous work process in terms of productivity.

Fourth, welding method using Tandem Laser source of A.W.S of USA. At this time, the allowable gap can be up to 0.3mm. This is a device that compensates the gap by making two laser heads at two laser sources and making laser focusing at two points. .

However, because two lasers are used, if the equipment is expensive and one of the two fails, it cannot be produced, and the equipment failure also lowers the operation rate of the equipment.

In addition, the laser has a disadvantage in that the productivity is gradually reduced because the production speed varies depending on the gap.

Therefore, the present invention manufactures a tailored welded blank (Tailored Welded Blank) excellent in productivity and quality in the press material process for welding and assembling a plurality of dissimilar steel sheet in accordance with the purpose in order to solve the above-mentioned conventional technical problems. The purpose is to provide a method for doing so.

Laser welding is affected by the gap between the two welded objects unless beam quality is a problem. The technical problem required in the manufacture of the TWB (Tailored Welded Blank) steel sheet is to minimize the gap between the two welded joints anyway. In the present invention, a weldable gap can be secured up to 0.4 mm in order to secure a good formability, so that the quality of the welded part and the quality of the welded part are not a problem during molding, and to maintain the highest productivity. It is an object of the present invention to maintain the formability of the welded part and the base material and improve the productivity 15% or more compared to the conventional laser welding speed.

1 is an explanatory diagram of a related apparatus for applying the welding roller system according to the present invention.

2 shows a general edge quality state in a laser butt weld.

3 is a step-by-step explanatory diagram of the process of the present invention for welding the upper edge.

Key symbols for the drawings:

1,1-1,1-2. Plate (blank) material 2,2-1,2-2. Upper roller 3. Lower roller

4. Position fixing platform 5. Plate support 6. Laser beam

7,8,9. Welder inspector

The present invention is based on a welding method using a rolling roll. That is, the present invention is the above-described automotive T.W.B. Rolling process using a roller system in the manufacturing process of steel sheet material, and in this case, the roller manufacturing method characterized in that the T.W.B. manufacturing method characterized in that the roller is used as an electrode roller. Plate refers to the welding of different materials or the thickness of different materials according to the application and then laser welding. Steel plates are used for automobiles. However, in most cases of laser welding, gaps are formed between two plates during press, shearing, etc., and this gap makes welding impossible and therefore rollers. It is necessary to serve to fill the gap by squeezing the plate on the thick side by rolling by the system. In the present invention, when the thicknesses of the two plates differ from each other as the to-be-welded material to be welded, as shown in FIG. In this case, the two boards are pulled into the shuttle type. At this time, the thin plate stops first, and then, if it is fixed, the thick plate is bitten and glued to the thin plate. Then, the roller system is started to operate the edge of the thick plate ( by pressing the edges together to close the gap between the two plates.

1 and 3 show the roller system of the present invention for rolling the edge cross section of the weld. Here, the upper rolls are usually two, and the rolls on the side of the thin plate serve as a supporting area for the plate. On the other hand, the upper and lower rolls on the thick plate side are composed of electrode rolls. One of the features of the roller system according to the present invention is used as an electric resistance electrode roller. Since a method of mash seam welding using electrode rolls is known, the description of electric resistance welding will be omitted.

As described above, the present invention has developed a device by replacing a roll with an electrode roll in a roller system. The following description will be made. As shown in FIG. 2, the influence of edge quality in laser butt welds is shown. Edge is influenced by straightness (Gap) and shear to break ratio, shear angle and shear direction, and is influenced by various factors such as burr. A gap occurs between the two welded objects. Therefore, this should be compensated by rolling the edge of thick material by a general roller system to fill the gap. However, as described above, when the shuttle type is used, not only the productivity is lowered but also the welded end portion becomes stronger, which impairs workability and worsens the durability of the roller system.

Therefore, in order to solve this problem, the present invention replaces a roller system with an electrode roll and performs rolling by resistance heating of the welded object with an electrode roller above the A ₃ transformation point before performing laser welding. In this case, not only the pressing force is reduced, but also the processing is easy, and even if the allowable gap is 0.3mm to 0.4mm, it is easily formed by rolling with the electrode roller, and the productivity is usually increased by 15% due to the preheating effect even in laser welding. In terms of quality, the hardness has been increased in the edge rolling state, but if it is pressurized using an electrode roller and cooled slowly around 50 ° C above the A ₃ transformation point, residual stresses are removed and the heat treatment effect after rolling (by electrode roller) Heating from A ₃ to around 50 ° C.) can be reliably obtained.

Referring to Figure 3 for the roller operation by the electrode roller in the present invention as follows.

First, the thick plate to be welded is loaded by a hydraulically loaded clamping jaws, and the plate is mounted on the lifting platform 4 and the plate support as shown in Fig. 3 (a). 5) Positioning stop between. Next, lift up the other lifting platform 4 and push the thin plate 1-1 to be welded toward the thick plate 1-2 so that the plate above the lower roller 3 as shown in Fig. 3 (c). Close the edges.

As a result of the above-mentioned causes in the close contact process, the thickness of the blank to be welded is different from each other as shown in Fig. 3 (b) between the two plates (1-1) and (1-2). There is a gap between the edges where the plate blanks abut.

Next, as shown in Fig. 3 (c), the lower electrode roller 3 serves as a support roller, and is positioned below the blank, and the upper electrode rollers respectively support rollers. The upper roller (2-1) of the thin plate and the upper roller (2-2) of the thick plate are positioned above the plate, which in the former case is supported by the support (5) and the position fixing platform (4). The plate 1-1 is held on and held by the upper roller 2-1 on the lower roller 3, which is the support roller, and in the latter case, the support 5 and the lifting platform 4 are also held. Plate (1-2) supported by the sheet) is heated and compressed by the upper electrode roller (2-2) on the lower support roller (3) to close the gap between the plates (1-1) (1-2). Fill it up. At this time, the upper and lower rollers (2-2) and (3) are constituted by electrode rollers, and the thick plate (1-2) is pressed by these electrode rollers (2-2) and (3) which are already heated to By heating the edge portion in the manner described above and pressing the thick plate at the same time to fill the gap between the two plate by stretching.

After welding, the clamping holding these plates is released and the plate transfer facilities are returned to their original position to transfer the next plate to the weld.

The present invention is characterized in that the welding speed is increased by easily pressing and pressing the sheet in the hot state compared to the conventional method by using the above-described mechanism, and also giving a preheating effect with the laser welding performed immediately. Here, the electrode rolls 2-2 and 3 are air-cooled after welding the plate, and then water-cooled with a conventional water-cooling apparatus, and then oiled to prevent rust. Of course, the joining of the plate is completed by the gap filling and welding by the above-mentioned compression.

According to the present invention, it can be seen that the welding speed with heterogeneous plates or plates with different thicknesses is usually improved by 15% or more (for example, the average value of 7.5 MPM to 8.6 MPM) according to the preheating effect of the welding heat. there was.

As described above, in view of the gap adjustment by the simple cold processing, the conventional roller system was able to increase the edge hot working effect by heating and rolling the welded object to 50 ° C. above the A ₃ transformation point by using the electrode roller of the present invention. As a result, it was possible to suppress the improvement of the material properties and the decrease of the service life due to the compressive strength of the rollers. In particular, welding was possible even when the gap between the plates was 0.4 mm. In addition, as described above, since the preheating effect before welding, productivity is also greatly improved.

According to the present invention, the conventional roller system was able to achieve a large edge rolling effect by heating the welded object to 50 ° C. above the A ₃ transformation point by hot rolling by using an electrode roller in view of the gap adjustment by simple cold machining. The improvement of material properties and the reduction of service life due to the roller's compressive strength could be suppressed. In particular, welding was possible even when the allowable gap was up to 0.4mm. In addition, since the preheating effect before laser welding, the productivity is also greatly increased compared to the conventional.

Claims (1)

In the method for welding manufacturing a tailored welded blank (T.W.B.) plate for automobiles by laser, Each outer end of each plate of different or different thickness is fixed up and down by the upper platform and the lower support, respectively, and the inner edge of the plate, which is the welded part to be joined, is used as a support roller. The upper electrode roller is brought into close contact with each other on the lower electrode roller, and then an upper roller as a non-contact roller is installed on the edge of the thin plate among the edges of the welded material placed on the lower electrode roller to prevent the thin plate from being pressed. The upper electrode roller as a welding roller is installed on the edge of the thick plate, and the upper and lower electrode rollers are energized in the state where the edge of the thick plate is pressed, and the welded object is heated to 50 ° C. above the A ₃ transformation point. Edge of the positive plate material by hot rolling the thick edge of the plate Extended well tailored blank manufacturing method of (TWB) plate using an electrode system, characterized in that the roller such that a gap between the bonding mekkueo.