JPS6123077B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing flux-cored wire that is applied to manual welding and automatic and semi-automatic welding. A rolling process is applied along the groove-shaped notch,
It is characterized by automatically filling the groove-shaped void to be formed with flux. Traditionally, in the production of flux-cored wire,
Polished strip steel having a substantially rectangular cross section that has been rolled and cut into appropriate dimensions has been used as a raw material for the outer shell metal, and there are a large number of technical papers and reports related to this. However, with the recent spread of flux-cored wire, the demand for this type of wire is increasing, and the price of raw steel strip is rising year by year, so the conventional manufacturing method, which uses polished steel strip as the main raw material, has begun to bring about various problems. Ta. In other words, to summarize these problems, first of all,
In response to the rapid increase in wire production, it has become difficult to secure a quantity of raw material steel strip with stable composition, and in recent years, the cost of product wire has increased due to the soaring price of steel strip. In particular, the former is considered to be an issue that should be extremely important in welding materials made from steel strips. Currently, from the above-mentioned viewpoints, it is common to use rimmed steel as the material for raw steel strips. However, as is well known, a steel strip material (hot coil) hot-rolled from a rimmed steel ingot forms a pure iron-like rim layer on the outside, while having a segregation zone of impurity elements such as P and S in the center. There are drawbacks. In order to overcome these difficulties, the present inventors
We have already developed a method (Japanese Patent Application No. 49-29480) for producing flux-cored wire by automatically filling the groove-shaped voids that appear during the plastic working process using welding rod wire as material (Japanese Patent Application No. 1982-29480), and published the results. It has gained. In other words, unlike steel strips, wire rods for welding rods are, in principle, steel ingots that are elongated in the longitudinal direction, so the rim and segregation bands have the advantage of being almost evenly distributed at each location of the wire. This is one reason why conventional welding methods using wire rods, such as manual welding, _Co2 welding, and submerged arc welding, have become more popular than flux-cored wire welding methods using strip steel. It is something that exists. Furthermore, in the case of wire rods for welding rods, the ladle analysis value almost represents the wire rod portion, which is advantageous in terms of quality control of raw material components. Furthermore, compared to steel strips, wire rods can be easily supplied in quantity as raw materials for welding materials. For the reasons mentioned above, in the present invention, a wire for welding rods is used as the material, especially from the viewpoint of composition. Furthermore, raw steel strips are normally regulated to prevent them from collapsing during transportation, as well as from rolling and cutting processes, and are supplied as small coils weighing around 100 kg, so they must be welded and joined fairly frequently during wire production. This increases the speed of wire production, but also has the disadvantage of significantly lowering the operating rate of the equipment. For the reasons described above, the present inventors have already developed the use of wire rods, particularly core wire rods for welding rods that are stable in terms of component quality, economical efficiency, and supply materials, as flux-cored wire raw materials. However, the present invention has conducted further research and developed a method for producing homogeneous flux-cored wire with high efficiency by plastically deforming the same wire most effectively. That is, the present invention involves roll processing on a continuous production line, in which a welding rod wire material is used as a raw material, a part of it is cut and removed in the shape of a continuous groove in the axial direction, and a rolling roll is press-fitted along this continuous groove. By applying this process, a continuous U-shaped groove is formed, and after this U-shaped groove is automatically filled with flux, the mouth of this groove is closed, and the wire drawing process is performed on the same production line, thereby reducing the raw material wire material. This method has succeeded in making the most effective use of the above-mentioned merits and improving production efficiency. In the manufacturing method of the present invention, first, a groove-shaped notch continuous in the axial direction is provided in the wire rod for the welding rod core on a continuous production line at the top in the axial direction, and the specific method is as follows. As described above, a commonly used cutting tool such as a rotary cutter or a cutting tool made of sintered alloy or high-speed steel is pressed against the running wire to cut a groove of the desired shape and depth on its surface. In this case, guide rolls on both sides are installed before and after the cutting tool to ensure the straightness of the wire and prevent the wire from wobbling. Note that one or more cutting tools are used depending on the degree of groove machining. In addition, this continuous groove-like notch also serves as a guide groove for press-fitting the roll during plastic deformation due to rolling in the next process, and its cross-sectional shape is U.
It is letter-shaped or V-shaped. Due to the difficulty of cutting, multiple cutting tools are used to first form a V-shaped cutting groove, and then the V-shaped tool is used to form a U-shaped groove for easy rolling.
By forming the groove, wear and tear on the tool can be minimized. Further, the depth is such that the depth of cut of the cutting groove is 10 to 67% for the purpose of reducing the roll guide effect during rolling and the work hardening of the wire to a target hardness or less. In other words, in the present invention, the lower limit of the cutting rate is set to 10% to prevent troubles during manufacturing such as wire disintegration and wire breakage during wire drawing due to work hardening, and from the viewpoint of wire feedability during welding. The upper limit is Bitkers hardness of 220,
This point was taken into consideration. It is clear that this is valid from the experimental results shown in FIG. 7, which will be described later. Therefore, if the depth of cut is less than 10%, the cross section of the wire will have a Vickers hardness of 220 or more, which is undesirable because it is likely to cause the various troubles mentioned above. Next, FIG. 1 shows through experiments that forming cutting grooves in a part of the drawn wire material is effective in minimizing work hardening of the wire sheath. In the figure, the horizontal axis represents the degree of wire processing, and the vertical axis represents the cross-sectional hardness of the wire sheath. As is clear from FIG. 1, the hardness of the outer skin of the wire when a portion of the wire is cut is lower overall than when the wire is not cut. Additionally, the cutting grooves also become deeper. In other words, depth of cut (=depth of cutting groove/wire diameter x
100%, see Figure 1) increases, the outer skin hardness tends to decrease. This is because the C and Mn contents of the drawn wire material that forms the wire sheath are high within the JIS standard component range and are easily work hardened.
It does not require intermediate annealing and is convenient for high-speed production of small diameter wires such as 1.2φ without troubles such as wire breakage. Therefore, the technology of the present invention makes it possible to cold-make a special steel wire containing alloying elements such as Cr, Mo, and Ni, which was difficult to produce using conventional methods. In this case, the experimental conditions are (1)
The wire rod is a 6φ welding rod wire that corresponds to the JIS G3503-1964 standard, (2) the type of filling flux is titania type for _Co2 welding, and (3) the flux filling rate is
It was 15%. Moreover, the experimental results shown in FIG. 2 show that by increasing the cutting depth, the outer skin hardness of the cold-formed small diameter wire decreases. By the way, in this experiment, (1) welding rod wire according to JIS G3503-1964 standard was used as the wire, (2) the filling flux was CaF ₂ -CaCO ₃ system for Co ₂ welding, and (3) the flux filling rate was
16% and (4) the final cold-made wire outer diameter is
The test was carried out under the condition of 1.2φ. As is clear from FIG. 2, as the depth of cut increases, the wire outer skin hardness decreases, and almost reaches equilibrium from 67% or higher. Therefore, taking into account the loss of the wire rod to be cut, the industrially effective upper limit of the cutting depth may be 67%. During roll rolling, a press-fitting roll is introduced and rolled using a continuous notched groove as a guide groove. Therefore, in a high-speed wire production line, the formability of flux-filled grooves by the method of the present invention is higher than that of conventional methods in terms of processing rate of wire cross section. It is much better because it equalizes. Furthermore, by providing the cut groove on the top, there is no line run-out during the initial forming process compared to the conventional method of roll-pressing round-section wire rods all at once, and as a result, the straightness and Flux-filled grooves with extremely high uniformity can be formed by roll processing. Therefore, according to the method of the present invention, it is easy to regulate the flux supply from the feed nozzle during automatic flux filling, the uniformity of flux filling is significantly improved, the wire manufacturing speed can be greatly improved, and the wire productivity is improved. It was a marked improvement. Furthermore, in the present invention, as described above, the work hardening of the wire rod is suppressed to the minimum due to the effect of the cutting process, and the rigidity of the part corresponding to the wire closing part of the processed groove is small, so it is easy to close the groove opening after filling with flux. Moreover, there is no loss of filling flux due to re-opening of the closed portion during wire handling. Furthermore, when manufacturing ultra-fine diameter wires, wire breakage caused by minute cracks that occur at the wire joints is a problem that often occurs.With the present invention, work hardening during wire manufacturing is suppressed to a minimum, so this problem is significantly reduced. hard. The present invention will be described in detail below based on examples. FIG. 3 is a block diagram showing an example of the method for manufacturing flux-cored wire according to the present invention. Hereinafter, the present invention will be explained in detail based on FIG.
First, a wire rod for a welding rod is supplied from a wire coil stand 1 having a required diameter, and drawn to a wire diameter suitable for rolling by a continuous wire drawing machine 2 (hereinafter, this wire rod is referred to as a wire drawing rod). Moreover, this drawn wire material can be annealed and softened by passing through a heating device 3, if necessary. In this case, annealing can be performed using any device that can perform the annealing while the wire is moving at high speed. For example, a method of heating a predetermined section of the drawn wire material by directly applying current to it via a current-carrying roll, or a method of induction heating using a high-frequency current are effective. This annealing process is necessary because the outer diameter of the raw hot coil wire is large, so the continuous wire drawing machine 2
This is a case where work hardening is significant when reducing the outer diameter to a predetermined outer diameter to obtain a drawn wire material. Therefore, if a relatively small-diameter soft wire rod hot-formed in a steel mill is selected as the raw material, this annealing step, which complicates the process, can be omitted. Next, the cutting step 4, which is an element of the present invention, is a processing stand equipped with one or more cutting tools in order to remove the top of the wire drawing material so that the next rolling step 5 can be easily performed. Moreover, incorporating this process into such a wire production line has an important meaning of preventing work hardening of the product wire, as will be described later. In the rolling process 5, first, rolls are sequentially press-fitted from the top of the drawn wire material that was cut and removed in the cutting process 4, and the powder and
Forms a U-shaped groove convenient for filling with granular flux. In this case, the cut groove in step 4 exhibits a guiding effect during roll press-fitting, making the U-shaped groove forming operation extremely easy. This makes the conventional method, which does not take such step 4 into consideration, more efficient. The rolled wire drawing material is filled with flux supplied from a flux hopper 9, and then passed through a conventional forming machine 6 and a continuous wire drawing machine 7, and then wound into a winding machine 8 in the form of a completed flux-cored wire.
Below, this flux-cored wire is the same as the conventional one.
Sent to drying and product coiling process. In this case, if the forming rolls of the forming machine 6 are driven in the same way as the rolling rolls, wire breakage will be less likely to occur and higher speed production will be possible. In addition, the drive methods for these rolls include one that adjusts the rotation speed of each individual roll to match the elongation rate of the wire material during processing, and one that adjusts the circumferential speed of all rolls, both of which are effective. be. However, the former is the composition of the filling flux,
Since it is easy to adjust the roll rotation speed in accordance with changes in the wire elongation rate due to changes in the density and flux filling rate, it is suitable as equipment for producing a wide variety of products in small quantities. By the way, one of the features of the method of the present invention is, needless to say, that the wire rod for welding rods is plastically worked into a shape that is convenient for flux filling. It is desirable to adopt the following method to facilitate the final wire drawing. From this point of view, the method of the present invention has great significance because it includes a cutting step, compared to the conventional method using only roll rolling. FIG. 4 shows an example A of wire rod processing carried out by the present inventor in comparison with a conventional example B. That is, in the method of the present invention, the top of the wire rod A supported by a guide roll is first cut with one cutting tool or a plurality of cutting tools arranged in series, and then the cut groove is used as a guide to perform rolling. Press the roll toward the center of the wire to form a U-shaped groove. As mentioned above, such a step has never been attempted in the conventional method. That is, in the conventional method, as illustrated in FIG. 2B, the top of the wire rod A is pressurized with a presser roll to form an occluded circular cross section, and then the roll is press-fitted toward the center of the wire. However, in this conventional method, the wire rod is work-hardened during the cut-out circle processing, and therefore, problems such as wire breakage are likely to occur during the subsequent wire drawing, especially when making a small diameter wire. On the other hand, in the case of the present invention, a fixed amount of flux adjusted according to the purpose of use is fed into the U-shaped flux-filled groove formed while minimizing work hardening, and the flux is completely filled into the U-shaped groove. to be filled. Thereafter, the opening of the U-shaped groove is closed with a roll and a chi, and in the process of ri, the wire is reduced in diameter with a roll or a wire drawing hole die to finish the wire with the required outer diameter. As mentioned above, the present invention, prior to roll press-fitting,
It is characterized by forming cutting grooves with a cutting tool, and this process is advantageous in minimizing work hardening of the wire rod, and since the cutting grooves serve as a guide during roll press-fitting, the wire rod during processing is It has been confirmed through experiments that the wire is less likely to deviate from the roll and enables higher-speed wire production. Further, in consideration of productivity, the cross section of the wire according to the present invention is preferably a simple tube shape as illustrated in FIG. Further, the form of the flux to be filled does not necessarily have to be in the form of powder or granules, but may be in the form of a paste to which water glass is added, for example, so as to be suitable for high-speed supply. Furthermore, as an example of the industrial application of the present invention, the performance of gas shield and non-gas shield welding wires produced by the production method of the present invention will be shown below. Example 1 (1) Type and outer diameter of welding wire Co ₂ welding wire 1.2
mm (2) Composition of flux powder Fill the wire with five types of flux having the compositions shown below in an amount of 15 to 16% of the total weight of the wire.

【table】

[Table] (3) Wire rod Outer diameter 6.5mm Chemical composition C 0.07% P 0.011% Si 0.01〃 S 0.012〃 Mn 0.46〃 Cu 0.032〃 (4) Number of cutting tools 1 piece (5) Depth of cut 15% (6) Rolling Number of roll stands: 5 (7) The 1.2 mmφ wire manufactured under conditions of a wire manufacturing speed of 700 m/min or more at the final diameter had a cross-sectional hardness of the outer skin of Hv215, and good productivity was achieved with no wire breakage occurring during manufacturing. . (8) Welding (JIS Z3111 and Z3112) Welding was performed under the following conditions. The wire feeding performance during welding was good and the arc state was stable, and the performance of the weld metal was also satisfactory as described below. Welding current 280A _Ca2 amount 20/min Welding voltage 23V Number of passes 10 passes Base material SM−41

[Table] Example 2 (1) Type and outer diameter of welding wire Non-gas shielded welding wire 2.0mm (2) Composition of flux powder Several types of flux with the following composition were added to the total weight of the wire at a rate of 16 to 17 mm. Fill in the range of %.

【table】

[Table] (3) Wire rod Outer diameter 8mm Chemical composition C 0.08% P 0.011% Si 0.01 S 0.022% Mn 0.55% (4) Number of cutting tools 3 (5) Depth of cut 20% (6) Number of rolling roll stands 4 Group (7) Wire manufacturing speed at final diameter: 600 m/min The 2.0 mmφ wire manufactured under the above conditions has a cross-sectional hardness of Hv200, and the hardness of the end, which corresponds to the wire closing part of the processing groove, is particularly low, making it difficult to process the closing process. It was easy and good productivity was obtained. (8) Welding (JIS Z3111 and Z3112) Welding was performed under the following conditions. The wire feeding performance during welding was good, there was no directivity of the wire, and the arc was stable, and the performance of the weld metal was also satisfactory as described below. Welding current 400A Number of passes 10 Welding voltage 30V Base material SM−41

[Table] As described above, the flux-cored wire manufacturing method of the present invention uses a particularly compositionally stable wire rod for welding rods, provides cut grooves in this raw material wire rod, and forms groove-shaped cavities obtained by plastic working. Because it is an integrated process of filling the wire with flux, forming, and drawing the wire, it has become possible to save labor at the wire production factory, improving productivity, as well as improving the product's flux filling rate and wire shape quality. Therefore, in the field of automatic welding, where there is a strong demand for higher quality and cheaper welding materials in the future,
In particular, the industrial value of the method of the present invention is high. It goes without saying that depending on the factory size and other circumstances, the steps before and after Step 4 in the diagram can be separated.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between the processing degree and the cross-sectional hardness of the wire sheath in the present invention, Fig. 2 is a diagram showing the relationship between the depth of cut and the cross-sectional hardness of the wire sheath, and Fig. 3 is a diagram showing the relationship between the cutting rate and the cross-sectional hardness of the wire sheath. FIG. 4A is a block explanatory diagram showing an example of the manufacturing method; FIG.
B is a diagram showing a conventional rolling method. 1... Wire coil stand, 2... Continuous wire drawing machine, 3... Heating device, 4... Cutting stand, 5...
...Rolling roll stand, 6... Forming roll stand, 7... Continuous wire drawing machine, 8... Winding machine, 9... Flux hopper.

Claims (1)

[Claims] 1 A continuous groove-like notch is cut in the axial direction of the coated arc welding rod core wire material, and the groove-shaped void formed by rolling along this groove-like notch is automatically filled with flux, and the forming process is performed. A method for producing a flux-cored wire.