JPS5997794A - Production of steel wire for welding - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing fully automatic and semi-automatic welding steel wire that is copper-plated and has excellent feedability.

Generally, 0.00 is used for 002 gas shield welding, MIG welding, etc.
Copper-plated welding steel wire with a diameter of 8 to 2.4 mm is used. These welding wires are normally used for welding while being wound around a spool or bobbin, or loaded into a cylindrical container called a pail nok. When these wires are used, they are installed in the feeder, which is an accessory device of the welding machine, and are connected to a flexible conduit tube extending 93 to 20 meters through the feed roller, welding torch,
Welding is often performed through contact tips.

There are three types of feeding methods for welding wire using flexible conduit tubes: push type, pull type, and push-pull type, but the bush type is used more often because it is easier to handle. However, the conduit tube of the bush type feeder is usually 3 m long, and when welding a wide area, a length of about 20 m is used, and at this time problems arise in wire feedability.

'The bath welding wire is required to be fed at a constant speed. However, the wire is affected by the contact resistance between the flexible conduit's guide tube, such as the liner, torch, and tip, and the resistance force of the flexible conduit tube's bending part and the resistance force that prevents it from passing through completely. There are almost no on-site operations in which flexible conduit tubes are in the WW state, and they are usually used in a bent state.The more bends there are, and the smaller the bend radius, the greater the resistance to passing through the bends. When the contact resistance becomes large, the feeding rate of the welding wire becomes uneven and eventually the feeding stops. This causes various welding defects such as instability of the welding arc, irregular bead shapes, poor fusion, and undercuts.

Under these circumstances, as welding work becomes more complex, faster, and wider, welding wires that have low frictional resistance with flexible conduit liners, can be fed smoothly and stably, and can always be fed at a constant speed. In other words, there has been a strong demand for a welding wire with stable feedability.

In order to improve the feedability of the Wise itself, as in the wire disclosed in Japanese Patent Publication No. 50-3256, liquid lubricating oil is applied to the surface of the wire, which has a sufficiently microscopically dense and smooth surface. Although methods are known for increasing the lubricating ability and reducing the feeding resistance, it has not always been possible to obtain a method that shows stable feeding performance. The reason for this is that the surface of the wire is dense and smooth, so it is difficult to apply liquid lubricant evenly and stably to the surface of the wire, and in order to achieve the desired performance, a large amount of lubricant must be applied. This is because they did not obtain the desired results. Furthermore, lubricating oil applied to the wire surface in an unnecessarily large amount only causes material change in the welded portion or adversely affects welding workability.

As a welding steel wire that overcomes the drawbacks of conventional wires, the present applicant has developed a wire disclosed in Japanese Patent Application Laid-open No. 144892/1983. A hexagonal-shaped horizontal groove is formed on the surface of this welding planer wire. This transverse groove is within an angle of 30 to 150 degrees with respect to the longitudinal direction of the wire,
This is a groove formed in the circumferential direction of the wire, and the groove as a whole exhibits a hexagonal pattern. With this wire, it is possible to deposit as little liquid lubricant as possible in a stable and uniform manner in the longitudinal direction of the wire. That is, since the liquid lubricant f is retained in the cracks on the wire surface and the surface of the wire becomes microscopically oil-impregnated, the contact resistance with the shiconduit liner, which has an extremely good lubrication ability on the wire surface, is reduced. As a result, the feeding resistance itself is low, the fluctuation range is narrowed, and the wire feeding performance is stabilized. By stabilizing and uniformizing the wire feeding performance, the shear arc is stable, and welding defects such as irregular bead shapes and poor fusion do not occur. Furthermore, since the liquid lubricant is kept in a stable state within the plating cracks, stable feeding is achieved with a minimum amount of wire adhesion, resulting in bits, blowholes, etc. caused by excess lubricant. Excellent welding workability is achieved without the occurrence of welding defects.

The present invention is a preferable method for manufacturing a welding steel wire with a hexagonal groove formed on the wire surface, which has good feedability, and improves the drawability of the wire, making the process continuous, and improving productivity. The purpose is to provide a manufacturing method that can In order to achieve this object, the present invention involves subjecting hot-rolled steel wire to a process of annealing in a neutral or reducing gas atmosphere, a descaling process, a wire drawing process, a plating process, and a skin pass wire drawing process. The gist is:

The manufacturing method of the present invention will be explained below in comparison with a conventional manufacturing method.

Conventionally, when manufacturing a welding steel wire having hexagonal grooves on the wire surface using a hot-rolled steel wire of 5 to 6 mmφ as a raw wire, the raw wire is subjected to a descaling process, a wire drawing process, an annealing process, It was manufactured by sequentially performing a plating process and a skin pass process. In this case, the annealing is a punch-type annealing performed in an atmospheric gas for the purpose of removing stress from the wire rod hardened by wire drawing. For example, 7 in a nitrogen gas atmosphere.
Batch annealing is performed at 00°C for 4 hours. Due to this annealing
The steel wire is lowered to a predetermined tensile strength and 91
J (The surface layer of the wire adheres to the surface of the shear wire in the previous process and is softened by moisture, lubricant, etc. brought into the F1 furnace, and becomes a hard internal oxide layer with a depth of several μm to 10 μm. Then, plating A part of the wire surface that deteriorates plating adhesion is removed by pre-treatment washing, and after the thickness of the internal oxidation layer is adjusted, plating such as copper plating is performed.

In this way, the wire rod exhibits a triple-layered masonry wire cross section, with a soft and elongated plating layer on the outer periphery, a hard inner diffused layer formed and trained by annealing in the middle, and an elongated wire material that has been softened and annealed inside. is obtained.

The plated steel wire thus obtained is drawn to a desired product diameter in a final wire drawing step. When the wire is drawn in the final wire drawing process, the adhesion between each layer is not impaired, and the thinnest and least elongated part of the intermediate internal oxidation layer whose thickness has been adjusted is used as the starting point, and the wire is drawn in the horizontal groove or in the circumferential direction of the wire surface. This results in the formation of tortoise-shell-shaped grooves on the wire surface.

In this conventional manufacturing method, batch annealing, which is long-time annealing of 2 hours or more, is arranged in the middle of a series of manufacturing steps, making it difficult to make each step continuous. This is because the time required for each process such as wire drawing and plating is within a few minutes.
This is because if only annealing takes several hours, an extremely long annealing furnace must be installed for continuous operation. Another drawback is that raw hot-rolled steel wire generally has a
The tensile strength varies by about kgf/Im2, but since such steel wires have been used for wire drawing in the past, they are prone to rough dies and wire breakage. -4 Good It did not exhibit good wire drawability.

The method of manufacturing steel wire for welding of the present invention can realize continuous manufacturing process by performing batch annealing at the beginning of each process, which requires a long time, which has been an obstacle to continuous process. This manufacturing method improves wire drawability by drawing a steel wire that has been softened after annealing and has less variation in tensile strength.

A specific example of the method for manufacturing a welding steel wire according to the present invention will be described below based on the flowchart of the manufacturing process shown in FIG.

lAi for carbon dioxide gas arc welding as original hot rolled steel wire
! A wire (,, rIs z3312), 5.5 mmφ was used and subjected to the following steps. FIG. 2(a) is a metallurgical microscope photograph (X400) showing a cross section of the original wire.

(,) Wire drawing annealing: This annealing process is applied to the product (0.8~2.4
The purpose is to obtain the appropriate tensile strength that the wire should have (mmφ), to reduce the variation in the tensile strength of the raw wire, and to form hexagonal grooves on the wire surface during the subsequent wire drawing process. This is done for the purpose of forming an internal oxidation layer on the wire surface. Therefore, this annealing should be carried out in an atmosphere with a very low oxygen content, i.e. 100 ppm.In order to reduce the oxygen content in the furnace, inert gas such as nitrogen gas or argon gas is used. , nitrogen gas, carbon dioxide, or other neutral gas atmosphere. Alternatively, annealing may be performed in an atmosphere of a reducing gas such as carbon oxide. In this example, nitrogen gas was used in consideration of running costs, safety, etc.

When annealing is carried out in such a gas atmosphere, the oxygen brought from oxygen sources such as moisture adhering to the wire subjected to annealing or impurities in the atmosphere gas is in an elevated state and the iron in the false wire is also absorbed. It reacts with alloying elements such as silicon and manganese, which have strong affinity, to form an internal oxide layer made of oxides such as Fe2SiO4 and FeMnO2 within approximately 10 μm from the wire surface.

At this time, some nitrides inevitably generated by nitrogen in the nitrogen gas atmosphere are also contained in the internal oxide layer. A small amount of iron oxide is also generated on the surface of the wire, but it is removed in the next descaling step along with the scale that is generated and present on the surface of the steel wire during hot rolling.

FIG. 2(b) is a metallurgical micrograph (x40'o) showing a cross section of an annealed steel wire, and it can be seen that an internal oxidation layer is formed.

To explain the preferred annealing conditions here, in order to achieve the purpose of softening annealing and the purpose of generating a hard internal oxide layer on the wire surface layer, the annealing temperature is 650°C in a neutral or reducing gas atmosphere or a mixed gas atmosphere. As mentioned above, it is desirable that the annealing time (holding time) is 1 hour or more. The lower limit of the annealing temperature is 650°C, in order to generate cracks on the wire surface during the wire drawing process in the later process, and to generate the amount of internal oxide layer necessary to obtain the entire wire for the desired welding process. the required temperature. On the other hand, there is no particular upper limit, but considering energy costs, it is preferably 900°C or less. Appropriate annealing time is determined depending on the annealing temperature, but when the annealing temperature is 650 to 900°C, the annealing time is preferably 1 to 5 hours, and if it is less than 1 hour, it is difficult to form an internal oxidation layer, and the annealing time is 5 hours. Exceeding this amount becomes wasteful in terms of energy costs. In this example, the temperature is 800℃ in a nitrogen gas atmosphere.
Batch type annealing was performed for 2 hours.

The steel wire thus annealed at a predetermined temperature and for a predetermined time to form an internal oxide layer and softened is cooled.
It is supplied to the next process.

(b) Mechanical descaling; (e) Pickling: The annealed steel wire is descaled before being drawn. This is because, in addition to scale during hot rolling, some iron oxides generated during annealing are present on the surface of the steel wire, and if the wire is drawn as is, it will adversely affect wire drawability. In addition, in (C) pickling, the thickness of the internal oxidation layer is adjusted so that hexagonal grooves are well formed in the wire drawing process in the subsequent process.

If the raw wire is descaled before annealing, the scale during hot rolling has been removed (
b) Mechanical descaling can be omitted.

(d) Wire drawing process: This wire drawing process reduces the steel wire to 5.5 m.
The area is reduced from mφ to 2.0 mmφ. The steel wire supplied to the wire drawing process is shown in Figure 2 (b), and has a cross section with a double structure: the surface layer is a hard internal oxidation layer with little elongation, and the internal steel wire is softened and elongated. ze, but
When this wire is drawn, tortoiseshell-shaped cracks occur in the internal oxidation layer in the circumferential direction of the wire surface due to the difference in elongation rate. The cracks on the wire surface that occur in this process, together with the cracks that occur in the subsequent skin pass wire drawing process, form hexagonal grooves on the wire surface that improve the feedability of the product welding pan wire.

(e) Plating pretreatment, (f) Plating treatment: After drawing the pot wire to reduce the diameter from 5.5 mm to 20 mm, pre-plating treatment is performed to pickle the wire to improve plating adhesion to the wire surface. After removing any foreign matter that may impair the quality of the wire and creating a wire with a clean surface, plating such as pot plating is applied. In this example, the wire was pickled by immersing it in 15% hydrochloric acid (temperature: 30° C.) for 2 minutes, and then electrolytic copper plating was performed at a current density of 2 A/dm 2 for a immersion time of 2 minutes.

(g) Skin pass treatment, (h) lubricant application Niskin pass treatment to polish the surface of the plated steel wire and reduce the wire diameter f2. O, mmφ to desired product diameter (
In this example, the diameter is reduced to 1.2 (positive φ). The wire subjected to the Sukijino 4 process has a soft and elongated plating layer on the outer periphery, an annealing process in the middle, and (d) elongation! A wire with a cross-section of a triple structure of a hard internal oxidation layer with cracks formed in the process, and a steel wire with internal elongation, and 9 steel wires are skin-pass treated without impairing the adhesion between each layer. Following the wire drawing process (d) in the previous step, tortoiseshell-shaped cracks are generated in the internal oxidation layer on the wire surface. A feeding lubricant is applied to the surface of the product wire, but when a liquid wire drawing lubricant used in skin-gloss wire drawing is used in combination, the lubricant application step (h) can be omitted. The lubricant applied to the wire surface is a liquid lubricant such as fat, mineral oil, or wet wire drawing lubricant.

In this manner, the manufacturing method of the present invention manufactures a welding steel wire through the steps (,) to (h). FIG. 2(C) is a metallurgical micrograph (X400) showing the surface condition of the product wire, and it can be seen that hexagonal-shaped cracks are formed on the surface. In addition, in the specific example of the above manufacturing process, (d) After the wire drawing process, the coiler makes the sheared wire into a loop with a diameter of 800 mm and conveys it horizontally on a conveyor to perform zero plating pretreatment, and (f) plating treatment. By passing it through, the steps from (d) wire drawing to (f) plating were made into a continuous process.

The steel wire for welding manufactured in this manner has a hexagonal-shaped crack on the surface of the wire, and liquid lubricant infiltrates into the crack, resulting in a stable microscopic oil-impregnated state. Therefore, by contacting the inner wall of the conduit liner during interrogation,
The liquid lubricant present in the cracks is discharged, resulting in good wire feeding performance with little variation.

EXAMPLES Table 1 shows changes in the tensile strength of steel wires when the method of manufacturing welding pot wires of the present invention is compared with all conventional examples. Both the present invention example and the conventional example used the same hot-rolled steel wire for carbon dioxide arc welding (JIS z3a12), 5.5 mmφ, as the raw wire. The example of the present invention is manufactured according to the steps shown in the flowchart of FIG. 1, and the conventional example is manufactured according to the steps shown in the flowchart of FIG. 1. In the flowchart of FIG. , 720°C x 4 hours).

As is clear from Table 1, the steel wire according to the present invention before wire drawing has a smaller variation (standard deviation) in tensile strength of about IA than the conventional example, and therefore has very good wire drawability. becomes. Incidentally, the variation in the tensile strength of the steel wire before the skin pass is small in both the inventive example and the conventional example, and the drawability during skin pass wire drawing is at the same level and is good in both cases.

Table 1 As explained above, the present invention is a method for manufacturing a steel wire for welding having a hexagonal-shaped crack on the surface, which improves the drawability of the steel wire and makes it possible to make the process continuous. The value is great.

[Brief explanation of the drawing]

Figure 1 is a flowchart of the manufacturing process of steel wire for welding according to the present invention, Figure 2 (a) is a metallurgical microscope photograph (x400) showing the cross section of the raw wire, and Figure 2 (b) is a wire drawing. A metallurgical microscope photograph (X40
0) and FIG. 2(c) are metallurgical microscope photographs (X400) showing the surface condition of the product wire. 1st Okaichi 4ε Figure 2 3

Claims (1)

[Claims] A process of annealing hot rolled steel wire in a neutral or reducing gas atmosphere, a descaling process, a wire drawing process, a plating process,
Skinno'? 1. A method for producing a welding steel wire having hexagonal grooves on the wire surface, the method comprising sequentially performing a series of wire drawing steps.