JPH0244634B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a flux-cored wire for welding,
In particular, it relates to a flux-cored wire for welding with improved feeding stability and straightness. [Prior Art] Flux-cored wire for welding is made by filling a metal sheath with powdered flux, and it is made with various raw materials (slag forming agent, arc stabilizer, gas The amount used has been rapidly increasing because it has the advantage of being able to incorporate flux components (generating agents, alloying ingredients, etc.), and has excellent welding workability and the ability to obtain beautiful bead shapes. . Most of the flux-cored wires currently used for welding have a diameter of 1.2 mm.
It has a circular cross section of 1.4 mm and 1.6 mm, and is used as a consumable electrode for carbon dioxide gas welding. [Problems to be solved by the invention] However, since the conductive part of a flux-cored wire for welding is essentially only the metal sheath, the current density during welding is higher than that of a solid wire of the same diameter, and the melting rate is low. fast. Therefore, the wire feeding speed must be considerably high, and in order to ensure stable welding workability under such high-speed feeding,
A high level of feed stability and straightness is required. Particularly recently, fully automatic welding has become popular in order to promote high efficiency and labor saving in welding work, and the length of the feed system has increased to more than 10 m, sometimes even 20 to 30 m, in order to expand the working range. In some cases, long wire feeding systems are used, and in order to respond to both trends in long wire feeding and high-speed welding, wire feeding stability and straightness are essential improvements. . Under these circumstances, in order to improve feeding performance and straightness, we eliminated curling and twisting of the wire, smoothed the wire surface, reduced feeding friction by applying lubricant, and improved the wire winding form. , etc. have been studied, and each has achieved some degree of effectiveness. However, depending on the feeding conditions, accidents may occur, such as the wire becoming distorted within the conduit tube, reducing feeding performance and straightness, or the wire buckling, making feeding impossible. The present invention aims to solve these problems and provide a flux-cored wire for welding that can provide a sound welded part with excellent feeding stability and straightness. [Means for Solving the Problems] The present invention provides a flux-cored wire for welding in which the inside of a metal sheath is filled with powdery flux. The gist is that ε is 25 to 55%. Elongation rate of the outer surface during local bending ε (%) =
d/D+d×100……(1) However, D: Minimum inner diameter that will prevent cracks from occurring when the wire is tightly wound several times in a spring shape d: Diameter of the wire [Function] Flux-cored wire for welding is generally Next 2
Manufactured by two methods. One method is to bend a metal band into a tube shape, fill it with powder flux, and then draw it to a predetermined cross-sectional dimension. In this method, powder flux is filled into the wire from the open end, and then the wire is drawn to a predetermined cross-sectional size. In order to increase productivity with these methods,
It is advantageous to make the diameter and thickness of the raw tube large before wire drawing, and it has come to be possible to increase the diameter and thickness of the raw tube as much as possible without impairing wire drawability. Furthermore, no particular consideration was given to the particle size of the flux filled inside, and from the perspective of reducing product costs, raw materials that seemed to be somewhat coarse were generally used. Therefore, the elongation rate ε of the outer surface due to local bending of currently commercially available flux-cored wires for welding is less than 25%. Here, the elongation rate ε of the outer surface due to bending is
This refers to the elongation rate at which no cracks occur when the wire is made into a spring shape and wound tightly several times as shown in FIG. 1, and is a value expressed by the following equation (1). Elongation rate ε (%) = {π (D + 2d) / π (D + d) - 1
}×100 = {D+2d/D+d−1}×100 = d/D+d×100 ……(1) However, D: Minimum inner diameter at which cracks do not occur when the wire is tightly wound several times in a spring shape, d : Diameter of the wire On the other hand, according to the present inventors, as the elongation rate ε increases, stable feeding performance can be obtained even in a bent welding posture, and distortion correction (so-called correction) in the manufacturing process of the wire itself can be achieved. It was confirmed that stable straight-line performance could be obtained. Furthermore, the present inventors conducted various studies in order to clarify the characteristics that would fully satisfy the feeding stability and straightness as a product wire. As a result, it was found that a product wire whose elongation rate ε is in the range of 25 to 55% can satisfy both of the above two requirements. That is, as will be clarified in the examples below, those whose elongation rate ε is within the range of 25 to 55%,
There is no risk of wire bending or buckling even in long feeding systems or feeding systems with considerable bends, and wire strain relief work during the manufacturing process can be carried out without any inconvenience. Therefore, stable straightness can be obtained. For wires with an elongation rate ε of less than 25%, feeding resistance increases in a bent feeding system, making feeding performance unstable, and strain relief during the manufacturing process may also be difficult due to wire breakage or broken wires. This becomes insufficient and the straightness becomes unstable. On the other hand, if the elongation rate ε exceeds 55%, the wire may bend due to feeding resistance or buckle within the feeding system, making feeding impossible. Note that the means for keeping the elongation rate ε of the outer surface during local bending within the above appropriate range is not particularly limited, and the area reduction rate necessary to draw the wire to the target cross-sectional dimension and the elongation accompanying it are not particularly limited. Depending on the degree of reduction, etc., the material and size of the material, the timing and conditions of intermediate annealing, etc. may be adjusted, and the particle size of flux particles filled inside may be adjusted depending on the area reduction rate. For example, using JIS G 3141 standard SPCE material, which is a typical sheath material, a 16 mm ^w × 1.2 mm ^t steel strip is formed into a tubular shape (6.3 mm) and 100 meshes (hereinafter abbreviated as #100) are formed.
For example, if a product wire of 1.2 mm or 1.4 mm is manufactured by filling the following powder flux and then wire drawing, the wire diameter is 4.0 mm.
By performing intermediate annealing (at 550 to 600° C.) for about 1 hour when the elongation decreases to ~4.5 mm, a product wire having an elongation rate ε within the above-mentioned preferred range can be obtained. However, the timing and conditions of intermediate annealing, flux particle size, etc. should be set arbitrarily depending on the physical properties and area reduction rate of the sheath material, and cannot be uniformly stipulated. It is also possible to secure an appropriate elongation rate ε without intermediate annealing by adjusting the area reduction rate, flux, etc. according to the mechanical and chemical properties of the steel. In addition, when performing intermediate annealing, the 500 to 700
It is desirable to carry out the process at a temperature of ℃ or below. [Example] A large number of flux-cored wires with different elongation rates ε were manufactured by using SPCE steel strips of various sizes as sheath materials and combining them with titania-based fluxes of various grain sizes (flux ratio: 13%). The feedability and straightness of each wire as a product wire were investigated. The results are summarized in Table 1 together with the flux particle size, intermediate annealing conditions, etc. However, the method for measuring wire feedability and straightness and the winding provided to the product wire were as follows. <Wire feedability> As shown in Figure 2, 6m conduit tube 1
A loop 1a (3 turns) with a diameter of 300 mm is formed in the center of the , and a curvature of 0.01 (R = 100 mm) is formed near the tip.
Three curves 2 are formed, a curved torch 3 is attached to the tip, and each test wire W wound around a wire spool 4 is fed into the conduit tube 1 by the feed roll 5. The feeding resistance and the feeding speed using the feeding speed measuring device 6 are measured. Then, the average feeding resistance value (upper row of Table 1) and feeding speed fluctuation rate V ₀ (lower row of Table 1) are determined. Here, the feeding speed fluctuation rate V ₀ is the ratio of the wire feeding speed V ₂ to the rotational speed V ₁ of the feeding roll 5 (see equation (2) below). V ₀ (%) = (1-V ₂ /V ₁ ) × 100 ... (2) The evaluation of wire feeding performance is the average feeding resistance value: 4
Kg, feeding speed fluctuation rate: Based on 10%, those below these values are judged as "Good: marked with ○", and those exceeding these values are judged as "Poor: marked with ×", and are shown in Table 1. shown respectively. <Wire straightness> As shown in Figure 3, 3m conduit tube 1
The curved torch 3 is attached to the tip of the welding tip 7, each test wire W wound around the wire spool 4 is fed into the conduit tube 1, and the wire W protrudes 150 mm from the tip of the welding tip 7. The straightness is judged by the magnitude of the runout. The deflection of the tip of the wire is expressed by the average value () of l from the average indicated point P to each indicated point 150 mm apart by continuously feeding 200 wires. : 2mm or less...○: 2-5mm...△ : 5mm or more...×

【table】

【table】

[Table] As is clear from Table 1, those with an elongation rate ε of less than 25% in local bending generally have many breaks and broken lines during the manufacturing process and have poor straightness. On the other hand, when the elongation rate ε exceeds 55%, buckling accidents occur during feeding. On the other hand, when the elongation rate ε is within the appropriate range of 25 to 55%, there are almost no wire breakage, wire breakage accidents, etc. during the manufacturing process, and the feedability and straightness are also good. [Effects of the Invention] The present invention is configured as described above, but the point is that the elongation rate ε in local bending is used as an evaluation criterion for product wires.
By setting the value within a specific range, a flux-cored wire for welding with good feedability and straightness was realized without causing any particular problems during wire drawing.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the shape of the wire, which is the evaluation standard for the elongation rate ε, Figure 2 is an explanatory diagram showing the wire feedability test method, and Figure 3 is an explanatory diagram showing the wire straightness test method. be. DESCRIPTION OF SYMBOLS 1... Conduit tube, 3... Curved torch, 4... Wire spool, 5... Feeding roll, 6... Feeding speed measuring device, 7... Welding chip, W... Test wire.

Claims (1)

[Scope of Claims] 1. A flux-cored wire for welding in which the inside of a metal sheath is filled with powdery flux:
A flux-cored wire for welding, characterized in that the elongation rate ε of the outer surface during local bending expressed by equation (1) is 25 to 55%. Elongation rate of the outer surface during local bending ε (%) =
d/D+d×100……(1) However, D: Minimum inner diameter that prevents cracks from occurring when the wire is tightly wound several times in a spring shape d: Diameter of the wire