JP2006341308A - Non-copper-plated wire for welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-copper-plated wire for welding capable of consistently melting a sliding contact to be formed between a power supply chip and a wire surface during the welding, and preventing any accidental solidification at the sliding contact during the continuous welding, and having excellent wire feedability and arc stability, and excellent welding workability with less spatter and fume. <P>SOLUTION: When the carbon dioxide gas-shielded welding is performed under the condition that the average current is 150-170 A, the power supply length of a power supply chip is 2-4 mm, the distance between the power supply chip and a base material is 20-24 mm, and the diameter of a free loop is 700-800 mm, the probability that the voltage drop between the power supply chip and a welding wire during the welding in a current area of 140-180 A exceeds 0.41 V is ≥70%. One or two or more of greases selected from a group consisting of vegetable, animal, mineral and synthetic oils is deposited on the wire surface by 0.25-1.5 g per 10 kg of the wire. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a copper plating-free welding wire that is a solid wire or flux-cored wire having no copper plating layer.

In general, for MAG (CO ₂ , CO ₂ + Ar) gas shielded arc welding, MIG welding, etc., a welding wire having a small diameter (diameter 0.8 to 1.6 mm) is used. The welding wire is used for welding in a form wound on a spool or loaded in a pail pack. At the time of welding using this welding wire, the wire is pulled out from the spool (or pail pack) by the feeding roller of the feeder, and pushed into the liner included in the subsequent conduit cable, via this liner, Feed to the power feed tip in the welding torch at the welding position.

  The conduit liner used here is a flexible guide tube formed by spiraling a steel wire, and the length is usually from about 3 to 6 m to a length from 10 to 20 m to the welding point. It is used in accordance with the selection. In such a series of welding wire feeding work, even if the welding site such as a construction site is narrow, or where there is a height difference or a bent part, regardless of these feeding conditions, It is necessary to supply the welding wire stably at a constant speed. This is the wire feedability which is one of the important quality characteristics of the welding wire.

  The welding wire is pushed into the conduit liner by the feeding force of the feeding roller, while receiving the feeding resistance due to contact friction from the inner surface of the conduit liner. At this time, when the conduit liner is in a simple use environment close to a straight state, the feeding resistance is not so large and no problem arises in feeding performance. However, in a complicated usage environment such as a large number of bending points, a small bending radius (curvature radius), or a long liner, the feeding resistance increases and the balance with the feeding force is increased. Collapse and feedability are significantly reduced.

  For this reason, in order to ensure stable feeding performance, it is necessary to lower the feeding resistance from the feeding liner. In order to reduce the feeding resistance and improve the feeding performance of the wire, generally, a lubricant (oil, solid lubricant) is applied to the surface of the wire for arc welding.

Conventionally, as a method for improving the feedability of the welding wire, an appropriate amount of oil is applied to the wire surface (Patent Document 1), and a solid lubricant such as MoS ₂ is applied to the wire surface. (Patent Document 2), annealing at an intermediate diameter to reduce wire strength, generating cracks in the wire surface, and retaining oil or the like inside the cracks (Patent Documents 3, 4, 5, 6), wire surface Techniques (Patent Documents 7, 8, and 9) have been proposed in which recesses are formed in the recesses and the recesses are filled with various powders.

  As described above, the prior art has been developed mainly for the purpose of reducing the wire feeding resistance during welding. For the purpose of improving the arc stability, a technique (Patent Documents 10, 11, and 12) in which a concave portion is formed on the surface of the wire and an arc stabilizer is filled in the concave portion has been proposed.

JP 08-157858 JP 06-285678 A JP 55-04-0068 JP-A-56-144892 JP 08-267284 A JP 2000-117486 A JP 58-184095 A JP 08-99188 JP2004001061 JP-A-5-069181 JP 2000-107881 A JP 2000-271780 A

  However, in the prior art described in each of the above-mentioned publications, since the sliding contact between the wire feeding tip and the wire surface is not stabilized, the conventional solid wire for arc welding has a wire feeding property. And arc stability are not always sufficient. For this reason, development of the wire for arc welding which has few spatter | spatters and fumes and has favorable welding workability is desired.

  As an important factor governing the feedability of the welding wire, the present inventors have solidified and fixed after the welding current flows from the power supply tip to the wire surface and the sliding contact is locally melted (hereinafter referred to as “fixed”). I found out that there is a phenomenon of fusion. When the power feed tip and the wire are fused, this force amplifies the frictional force on the inner surface of the conduit liner and significantly increases the feed resistance. When the feeding resistance exceeds 10 kgf, the clamping force of the feeding roller is exceeded, and slip occurs between the roller and the wire. Since the feeding roller is generally harder than the welding wire, the surface of the wire is scraped by slip, and the metal powder mainly composed of the shavings accumulates inside the conduit liner or power feed tip, thereby improving the feeding performance of the wire. Inhibit.

  The present invention has been made in view of such problems, and stably melts the sliding contact formed between the power supply tip during welding and the wire surface, and suddenly breaks at the sliding contact during continuous welding. An object of the present invention is to provide a copper plating-free welding wire that is excellent in wire feedability and arc stability without causing solidification, and has good welding workability with less spatter and fume. .

  The welding wire without copper plating according to the present invention uses a power supply tip having a power supply length of 2 to 4 mm at an average current of 150 to 170 A, and the distance between the power supply tip and the base material is 20 to 24 mm. When the diameter of the free loop caused by the wire winding is 700 to 800 mm and the carbon dioxide gas shield welding is performed, the gap between the power supply tip and the welding wire at the time of welding in the current range of 140 to 180 A is obtained. The probability that the voltage drop amount exceeds 0.41V is 70% or more, and one or two or more types of oils and fats selected from the group consisting of vegetable oil, animal oil, mineral oil and synthetic oil are 0.25 to 10 kg per 10 kg of wire. It is characterized by adhering 1.5 g.

  In this welding wire without copper plating, the probability that the voltage drop amount exceeds 0.41 V is preferably 80% or more. Further, it is more preferable that the probability that the voltage drop amount exceeds 0.41 V is 90% or more.

Moreover, in this invention, 1 type (s) or 2 or more types selected from the group consisting of MoS ₂ , WS ₂ , and ZnS are provided on the surface of the wire surface or a surface layer portion having a depth of 100 μm from the wire surface to 0.1. It is preferable that 01 to 0.25 g is attached.

  According to the present invention, the sliding contact formed between the power supply tip and the wire surface at the time of welding can be stably melted and solidified suddenly at the sliding contact at the time of continuous welding. There is no. Thereby, the wire feeding property and the arc stability are excellent, and a welding wire having good welding workability with less spatter and fume can be obtained.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. According to the present invention, the feeding resistance of the welding wire is essentially generated by the flow of the welding current, and a mechanical force such as a frictional force between the wire and the conduit liner is simply used. It was made based on the idea that it was not due to stress.

  FIG. 1 shows an apparatus for measuring the fusing force and feeding resistance. The welding wire 11 unwound from the reel 1 is supplied to a conduit liner 3 (length: 6 m) by a feeding roller 2 and is fed through the conduit liner 3 and fed to a torch 5. The feeding roller 2 is fixed on the table 4b, and the table 4b is provided on the gantry 4a so as to be movable in the wire feeding direction. The conduit liner 3 is formed with a one-turn curved portion in the middle in order to give a mechanical resistance to the welding wire inserted through the inside. The end of the conduit liner 3 on the feed roller 2 side is supported by a support device 8, and this support device 8 is fixed on the gantry 4a. A welding voltage is applied between the power supply tip 30 of the torch 5 and the welded plate 6 by a commercially available thyristor-controlled welding power source 12, and the welding wire 11 delivered from the torch 5 and the welded plate 6 are connected. An arc is formed. When the welding wire 11 fed from the feeding roller 2 passes through the conduit liner 3 and is fed from the torch 5 toward the welded plate 6, the feeding resistance acting on the welding wire 11 is the welding wire 11. Becomes a stress that presses the movable table 4b. Therefore, a load cell 9 is provided between the support device 8 or the gantry 4a and the movable table 4b, and the stress is applied to the stress between the feed roller 2 and the support device 8 or the gantry 4a. Obtained by measuring the repulsive force when going away from 2, and thereby the feeding resistance.

  In addition, the load cell 5 a is attached to the center of the torch 5, and the fusion force between the power feed tip 30 and the wire 11 is measured. The load cell 5 a has a hole through which the wire 11 can pass at the center, and the wire 11 passes through this hole and reaches the power supply chip 30. When a welding current is supplied from the power supply tip 30 to the wire 11, a local fusion occurs between the power supply tip 30 and the wire 11, and the power supply tip 30 receives stress downward by the wire 11. This stress is measured using the load cell 5a. Hereinafter, the stress acting on the power supply chip 30 is referred to as chip resistance. When a welding current flows through the load cell 5a, the load cell 5a is burned out. For this reason, the load cell 5a is electrically completely insulated from the torch 5, and the welding current is directly supplied from the welding power source 12 to the power feed tip 30.

  Further, a hall element 10 is provided in the current supply cable of the welding power source 12, and a welding current is obtained as the hall current detected by the hall element 10. The welding voltage is obtained by detecting the voltage between the torch 5 and the plate 6 to be welded by the voltmeter 7. These feeding resistance, tip resistance, welding current and welding voltage are input to the measuring instrument 12 and recorded.

  FIG. 2 is a graph showing the relationship between the welding current measured by this measuring apparatus and the feeding resistance. When the welding current does not flow (when the welding current is 0), even if the welding wire 11 is fed at a speed of 12 m / min, the feeding resistance is small (20 N or less). And only a simple mechanical frictional force between the conduit liner 3 and the like. On the other hand, when welding is started and the welding current is increased, the feeding resistance is increased particularly after the welding current exceeds 100A. In FIG. 2, the average value of the feeding resistance at each welding current is indicated by ■, and the upper limit value and the lower limit value of the dispersion of the feeding resistance are indicated by error bars. As shown in FIG. 2, when the welding current is increased, the feeding resistance is increased and the variation of the feeding resistance is also increased. As described above, the feeding resistance is generated when a welding current flows between the feeding tip and the welding wire. As the welding current increases, the feeding resistance increases and the variation thereof increases.

  This increase in feeding resistance is due to the fact that a welding current flows from the power supply tip of the torch 5 to the welding wire 11 and the sliding contact is melted and then fused. As a result of experimental studies by the present inventors, the most effective method for reducing this fusion force is that the sliding contact is stably softened during welding and the molten state is continued. I found it. Even if the welding current flows, if the sliding contact is stable and solid, or is softened or melted stably, the fusion force is reduced, the chip resistance is reduced, and the feeding resistance is also reduced.

  This principle does not depend on the type of welding wire, and does not depend on the surface state of the wire, for example, the type of metal plating. The welding current is generally several tens to several hundreds A, and it is difficult for such a high current to flow through the sliding contact so that the sliding contact is always in a solid state. Practically, it is preferable to always soften and melt rather than repeating intermittent softening, melting and solidification.

  Whether the sliding contact is constantly softened or melted needs to measure the temperature of the sliding contact, but it is difficult to directly measure the temperature of the sliding contact, and some alternative value is necessary.

It is the free electrons in the metal that carry the current and heat flow in the sliding contact. Based on this principle, a certain relationship expressed by the following formula 1 is established between the contact temperature (T _max ) and the voltage drop amount (E _C ) at the contact. Here, _TERT is the temperature of the power feed tip, and L is the Lorentz number (2.45 × 10 ⁻⁸ (V / K) ² ).

From this relationship, it can be seen that when the voltage drop amount (E _C ) increases, the contact temperature T _max increases, and when the voltage drop amount (E _C ) exceeds a certain value, the contact melts. Specifically, for example, if the power supply chip temperature _TERT is room temperature (300K), the amount of voltage drop at which the copper constituting the power supply chip is melted (melting point 1356K) is 0.41V. Further, the relationship between the voltage drop amount E _C and the contact temperature T _max when the temperature T _{ERT of the} power feeding chip becomes 300K, 400K, 500K, 600K, 700K, 800K, and 900K is as shown in FIG. In FIG. 3, the leftmost curve is the case where the power supply tip temperature _TERT is room temperature (300K), and the power supply tip temperature _TERT increases to 400K, 500K, 600K, 700K, 800K, and 900K as it goes to the right. To go.

  A conventional wire without copper plating has a relatively low surface contact electric resistance and a large variation, so that there is a large variation in the voltage drop amount, which is 0.41 V (hereinafter, “ Widely distributed above and below the melting voltage.

This voltage drop amount can be adjusted by adjusting the surface state of the welding wire. Specifically, there are the following five methods.
(1) The skin pass process using fats and oils in the final process, which has been considered essential in the past, is omitted.
(2) Up to the final product diameter, after drawing to the final product diameter with a lubricant containing one or two kinds of Na soap or K soap, washing with water having a temperature of 30 ° C. or more and drying. , Improve the electrical uniformity of the wire surface. Furthermore, the electrical resistance of the wire surface is uniformly increased by treating the wire surface with hot water or hot high pressure steam.
(3) By using roller die drawing or micromill drawing using a dry lubricant as appropriate, uniform irregularities in the wire longitudinal direction are generated on the wire surface. By forming this minute and smooth convex portion, the electrical resistance of the surface is uniformly increased.
(4) After drawing to the final product diameter, using a strand furnace, a high frequency induction heating furnace, or the like, an ultrathin oxide film is formed on the wire surface at a temperature and time at which the wire surface is not subjected to excessive surface oxidation. This uniformly increases the electrical resistance of the surface.
(5) The sulfide is left on the wire surface.

  By using these methods in combination in accordance with factory production equipment, the wire surface can be easily melted. The wire surface is always softened and melted uniformly by the welding current by generating and leaving uniform fine and smooth protrusions, ultra-thin oxide film, and sulfide throughout the entire length and circumference of the wire surface. I found out that The present technology can be applied to a solid wire that does not contain flux and a flux-cored wire that contains flux.

  The voltage drop during welding is measured by the following method. When a normal power supply chip is used, since the length of the power supply hole is about 40 mm, the wire and the power supply hole are contacted by a plurality of contacts. Even when the amount of voltage drop between the power supply chip and the wire is measured in a state of contact with a plurality of contacts, the amount of voltage drop is measured to be extremely small because the plurality of contacts are in parallel.

  Therefore, as shown in FIG. 4, the insulation sleeve is inserted, leaving only the tip of the power supply tip 2 to 4 mm, welding is performed in a state where the contact is macroscopically located, and the amount of voltage drop is measured. . 4A is a cross-sectional view showing the power supply chip, and FIG. 4B is a cross-sectional view showing a torch equipped with the power supply chip. The torch 20 is covered with an insulating cover 22, and a cable 21 is connected thereto, and the welding wire 11 is sent to the torch 20 through the cable 21. A conductive connecting portion 23 is provided at the lower end of the torch 20, and a power cable 24 is connected to the connecting portion 23. A part of the lower surface of the connecting portion 23 protrudes downward, and the upper end portion of the main body 31 of the power supply chip 30 is screwed to the protruding portion. Therefore, the power cable 24 and the main body 31 of the power feeding chip 30 are electrically connected via the conductive connection portion 23. In addition, an insulating cylinder 25 is fitted around the protrusion, and a sleeve 26 is fitted and connected to the outside of the insulating cylinder 25. A power supply chip 30 is disposed in the sleeve 26. The insulating cylinder 25 is provided with a shield gas introduction pipe 27, and the shield gas is supplied into the sleeve 26 through the introduction pipe 27. The power feed tip 30 is provided with a hole through which a welding wire is inserted at the center of the main body 31, and an insulating sleeve is provided on most of the peripheral surface except for the 3 to 4 mm portion of the power feed tip tip 33 in the hole. 32 is provided. The insulating sleeve 32 has an inner diameter of 2.0 mm and an outer diameter of 3.2 mm, for example, so that the welding wire and the main body 31 are not in electrical contact with the conductive main body 31. On the other hand, at the tip 33 of the power feed tip 30, the size of the hole is slightly larger than that of the welding wire, the diameter is smaller than that of the insulating sleeve 32, and the welding wire passing through the conductive main body 31 and the hole. 11 is in direct contact. Thereby, the welding current is directly supplied to the tip 33 of the power feed tip 30. No current is supplied to the welding wire from other metal parts. The anode 28 is electrically connected to the power supply chip 30 in the sleeve 26, a cathode is attached to the end of the wire wound around the spool 1, and the potential difference between the anode 28 and the cathode (not shown) is digital. It is measured with a recorder (not shown).

For example, in the case of a wire having a diameter of 1.2 mm, welding may be performed with an average current of 150 to 170 A using the torch 20 and the power feed tip 30. In the present invention, the average current is a time average of welding currents observed with a current meter of a welding machine. If the internal resistance of the digital recorder is sufficiently large, the current flowing through the potential difference recording circuit can be ignored, and the end of the welding wire 11 in contact with the power feed tip 30 and the end of the welding wire 11 wound around the spool 1 are Equipotential. Thereby, by measuring the potential difference between the anode 28 and the cathode, the potential difference between the welding wire 11 and the tip portion 33 of the power feed tip 30 can be measured. The welding current waveform is taken into the digital recorder in complete synchronization with this potential difference signal. For detection of the welding current, a shunt or a Hall element 10 may be used. It is desirable to use the Hall element 10 because it is resistant to noise. The shield gas may be welded with 100% CO ₂ and the relationship between the welding current and the voltage drop may be measured. This is because the current value fluctuates greatly by welding under the condition that an instantaneous short circuit occurs, and the voltage drop in the current from about 100 A to 400 A can be measured. An example of the measurement is shown in FIG.

  5A and 5B show the results of plotting the relationship between the welding current value at each time and the voltage drop amount at the corresponding time. FIG. 5A is a comparative example that is out of the scope of the present invention, and FIG. 5B is an example that falls within the scope of the present invention. Even if the average current is 160 A, since the droplet repeats the short-circuit transition and the globule transition, the current at that moment is distributed over a wide range from 20 A to 400 A. The instantaneous voltage drop is plotted against each current value, and the state of the contact can be estimated from this voltage drop amount. The melting voltage of metallic copper is 0.41V. Therefore, the critical voltage drop amount at which the contact is stably softened and melted is 0.41V.

  FIGS. 6A and 6B show probability density distributions of voltage drop amounts in the 40A range where the instantaneous current values of FIGS. 5A and 5B are 140A to 180A. Specifically, the voltage drop amount and the welding current are time-synchronized, for example, measured at intervals of 2 ms, and the ratio of plots exceeding 0.41 V among all plots having current values of 140 to 180 A was obtained. Is. That is, in FIGS. 6A and 6B, the probability density that the voltage drop amount exceeds 0.41 V is integrated (the area of the hatched portion), and the probability that the voltage drop amount exceeds 0.41 V is obtained. FIG. 6A shows the probability density distribution of the voltage drop amount of a conventional wire without copper plating, and the probability of exceeding 0.41 V is about 0.5. When welding is performed using such a wire, the sliding contact is repeatedly melted and solidified, so that fusion frequently occurs and stable welding cannot be performed. On the other hand, FIG. 6B shows a wire according to an embodiment of the present invention, and the probability of exceeding 0.41 V is 0.9 or more. In the wire of the embodiment of the present invention, the sliding contact is always melted and stable welding can be performed.

From such knowledge, in the present invention, a welding wire without copper plating that can achieve the effects of the present invention,
(1) A free loop caused by wire wrapping using a power supply chip having a power supply length of 2 to 4 mm at an average current of 150 to 170 A and a distance between the power supply chip and the base material of 20 to 24 mm. When the carbon dioxide gas shield welding is performed with the diameter of 700 to 800 mm,
(2) It is defined that the probability that the voltage drop amount between the power supply tip and the welding wire at the time of welding exceeds 0.41 V is 70% or more in the current region where the instantaneous current value is 140 to 180A.
(3) Further, in the welding wire without copper plating of the present invention, one or two or more kinds of oils and fats selected from the group consisting of vegetable oil, animal oil, mineral oil and synthetic oil are 0.25 to 1 per 10 kg of wire. .5g is attached.

  The condition (1) is a welding condition when the voltage drop amount (2) is measured. In the present invention, welding is performed in the entire range where the average welding current is 150 to 170 A, and the voltage drop at that time is measured. For example, even if welding is performed at an average welding current of 160 A, that is, even if an instruction value of 160 A is set in the current meter of the welding machine, the actual current instantaneously varies from 20 to 400 A. From this varying current, the voltage drop at 140A to 180A is extracted as will be described later.

  As shown in (2), welding is performed with an average welding current of 150 to 170 A, and the actual current is 140 to 180 A from the plot (FIG. 6) showing the relationship between the actual current and the voltage drop amount. It is necessary to extract the plot, and the ratio of the voltage drop amount exceeding 0.41V is 70% or more, that is, the probability that the voltage drop amount exceeds 0.41V is 70% or more. is there. When this probability is 70% or more, even if welding is performed at any current in a feeding system in which a 6 m conduit liner cable is wound once in the middle, the feeding resistance does not exceed 60N. This is shown in FIG. 11 of the embodiment described later. Therefore, in the wire of the present invention, the probability that this voltage drop amount exceeds 0.41 V is 70% or more.

  On the other hand, if the amount of oil in (3) is below the lower limit value of 0.25 g / 10 kg of wire, the feeding resistance exceeds 60 N due to the mechanical frictional force of the conduit liner. On the other hand, when the amount of oil in (3) exceeds 1.5 g / 10 kg of wire, the amount of clogging in the conduit liner increases, and slipping at the feeding roller occurs.

  If the probability that the voltage drop exceeds 0.41V is 80% or more, the feed resistance may exceed 50N even if welding is carried out at any current in the feed system wound once in the middle of the 6m conduit liner cable. Absent. This is shown in FIG. Therefore, it is preferable that the probability that the voltage drop amount exceeds 0.41 V is 80% or more. Furthermore, assuming that the probability that the voltage drop exceeds 0.41V is 90% or more, the feed resistance exceeds 40N even if welding is performed at any current in the feed system wound once in the middle of the 6m conduit liner cable. There is nothing. This is shown in FIG. Therefore, it is more preferable that the probability that the voltage drop amount exceeds 0.41 V is 90% or more.

Furthermore, in the present invention, one or two or more selected from the group consisting of MoS ₂ , WS ₂ , and ZnS are added to the surface of the wire surface or a surface layer portion having a depth of 100 μm from the wire surface with a ratio of 0.1 or more per 10 kg of wire. It is preferable that 01 to 0.25 g is attached. In a feeding system in which one or more selected from the group consisting of MoS ₂ , WS ₂ , and ZnS is attached in an amount of 0.01 g or more per 10 kg of wire, one turn in the middle of a 6 m conduit liner cable In any welding condition, the variation range of the feeding resistance does not exceed 10N. On the other hand, if the amount of adhesion exceeds 0.25 g / 10 kg of wire, the amount of clogging in the conduit liner cable becomes excessive, which is not preferable.

  This correspondence between the amount of voltage drop and the state of the sliding contact is a basic phenomenon that can be realized without distinction between solid wire and flux-cored wire. The state of the sliding contact is also affected by how much force the wire contacts the power feed tip. When the contact force is zero, the contact electrical resistance becomes infinite and stable power feeding cannot be performed. If the contact force of 50 gf or more can be maintained, the sliding contact will be stabilized. When the apparent diameter (free loop diameter) of the wire passing through the power supply tip is 700 to 800 mm, the sliding contact is stabilized if the wire surface is properly adjusted without distinction between solid wire and flux-cored wire. .

  Next, a description will be given of a voltage drop when a wire is drawn by a roller die using a solid wire having no copper plating. Table 1 below shows the composition of the welding wire used.

  An original wire having a diameter of 5.25 to 5.6 mm was pickled, and then wire drawing was performed by combining a hole die and a roller die. In the step of drawing a wire having a diameter of 5.5 mm until the diameter reaches 1.2 mm, the total diameter reduction amount is 4.3 mm. FIG. 7 is a graph showing the diameter reduction amount using a roller die (roll diameter reduction amount) on the horizontal axis and the voltage drop amount during welding on the vertical axis. The probability that the voltage drop at that time exceeds 0.41 V is shown in Table 2 below. In Table 2, “the threshold voltage with a probability exceeding 70%” means a voltage with a probability of 70% when the voltage drop amount exceeds the threshold voltage in the graph shown in FIG. is there. For example, in Example 2, the “threshold voltage with a probability exceeding 70%” is 0.46V, and this is because the probability that the voltage drop amount exceeds 0.46V (integrated probability density) is 70%. Is meant to be. Therefore, at 0.41 V lower than 0.46 V, the “probability that the voltage drop amount exceeds 0.41 V” in Example 2 is 76%, which is higher than 70%.

  It can be seen from FIG. 7 that the voltage drop is clearly improved by reducing the diameter using a roller die (as the roll diameter decreases).

  In addition, after intermediate annealing at a diameter of 2.4 mm, pickling, drawing with Na soap using a hole die to the final diameter, and then thoroughly washing with hot water of 30 ° C. or more, to the surface An extremely thin oxide film is formed, and the voltage drop is clearly improved. FIG. 8 shows the relationship between the product of the temperature of cleaning water and the cleaning time on the horizontal axis and the amount of voltage drop on the vertical axis. The probability that the voltage drop at that time exceeds 0.41 V is shown in Table 3 below. It can be seen that the amount of voltage drop during welding increases as the cleaning time increases or the temperature of the cleaning water increases.

  Further, the wire was instantaneously heated to a high temperature in the atmosphere using a high frequency induction heating device (oscillation frequency: 20 kHz). FIG. 9 shows the relationship between the induction heating temperature and the voltage drop during welding. Table 4 below shows the probability that the voltage drop amount at that time exceeds 0.41V. It can be seen that when the heating temperature is 300 ° C., the amount of voltage drop increases rapidly. When the temperature of the wire was raised above 450 ° C., the wire was annealed and softened, and there was a problem as a welding wire.

  FIG. 10 shows the relationship between the amount of ZnS on the wire surface and the amount of voltage drop, with the amount of ZnS on the horizontal axis and the amount of voltage drop on the vertical axis. Table 4 below shows the probability that the voltage drop amount at that time exceeds 0.41V. As shown in FIG. 10, the amount of voltage drop is increased by applying an appropriate amount of oil and ZnS to the wire surface. It can also be seen that the amount of voltage drop increases as the amount of ZnS increases. In addition, it has been clarified that other sulfides have the same relationship.

  Next, an experiment was performed using a solid wire having a chemical composition equivalent to JIS YGW11. Table 2 below shows the composition of this solid wire.

  Pickling when the diameter is 5.25 mm, and then performing cold wire drawing, cleaning, and surface treatment with the contents shown in Examples 1 to 5 below to finish the wire with a diameter of 1.170 to 1.200 mm It was. For surface treatment, palm oil was used as vegetable oil, beef tallow was used as animal oil, and polyisobutene was used as synthetic oil. In addition, the same effect was confirmed also about the wire finished to the diameter of 0.6 thru | or 1.6 mm, and the wire with a flux.

  The degree of the effect is adjusted by changing the welding current using the experimental apparatus shown in FIG. 1 to an appropriate voltage, using a torch with a length of 6 m, and making a one-turn curve so that the diameter becomes 300 mm in the middle. The feeding resistance in the feeding system was measured and the feeding performance was evaluated.

"Example 1"
Until the diameter is changed from 5.5 mm to 1.2 mm, dry-draw wire with Na soap using all hole dies, soak and wash in hot water at 60 ° C for 2 seconds at the product diameter, dry and then synthesize 0.8 g of oil was applied per 10 kg of wire. The skin pass of the reduction surface using fats and oils in the product diameter is not performed.

  FIG. 11 shows the relationship between the welding current and the feeding resistance in this case. The upper limit value of the feeding resistance is less than 60N. The feeding force of the feeding roller is about 100N, and if the upper limit value of the feeding resistance is less than 100N, the feeding roller does not slip and the generation of metal powder or the like can be prevented. Although slight wire speed fluctuation occurs, the minimum necessary condition that the metal powder does not clog the power supply tip, spring liner, conduit tube, etc. due to the metal powder is satisfied.

"Example 2"
Until the diameter is changed from 5.5 mm to 2.4 mm, dry drawing is performed using Na soap with all the hole dies, and roller die drawing is performed until the diameter is changed from 2.4 mm to 1.25 mm. Until the diameter is changed from 1.25 mm to 1.2 mm, dry drawing with Na soap is performed with a hole die, and immersion cleaning is performed for 2 seconds with 70 ° C. hot water at the product diameter. 0.8 g was applied per 10 kg of wire.

  FIG. 12 shows the relationship between the welding current and the feeding resistance in this case. The upper limit value of the feeding resistance is less than 50N, the feeding speed fluctuation is reduced, and the amount of spatter generated is also reduced.

"Example 3"
Until the diameter is changed from 5.5mm to 1.28mm, wire drawing mainly using Na soap is performed with a roller die, and when the diameter is 1.28mm to 1.2mm, dry drawing using Na soap is performed with a hole die. Then, immersion cleaning was performed for 2 seconds with 65 ° C. hot water at a product diameter, and after drying, 0.8 g of synthetic oil was applied per 10 kg of wire.

  FIG. 13 shows the relationship between the welding current and the feeding resistance in this case. In the third embodiment, the feeding resistance is further stabilized, and the probability of occurrence of a welding defect or the like even at a high current is extremely reduced.

Example 4
Until the diameter was changed from 5.5 mm to 1.25 mm, wire drawing with K soap was mainly performed with a roller die, and Na soap was used with a hole die until the diameter was changed from 1.25 mm to 1.2 mm. Dry wire drawing was performed, and immersion cleaning was performed for 2 seconds with 65 ° C. hot water in the product diameter. After drying, 0.8 g of synthetic oil was applied per 10 kg of wire, and 0.015 g of MoS ₂ was applied per 10 kg of wire.

  FIG. 14 shows the relationship between the welding current and the feeding resistance in this case. The feed resistance is stabilized at a low level, and the amount of spatter and fume generated is greatly reduced.

"Example 5"
Until the diameter is changed from 5.5 mm to 1.25 mm, a soap selected from Na soap and K soap by a roller die, an inorganic softening point adjusting agent such as nitrite and phosphate, MoS ₂ , WS ₂ , And a mixture with a sulfide selected from the group consisting of ZnS is mainly used as a lubricant, and until the diameter is changed from 1.25 mm to 1.2 mm, a dry method using Na soap with a hole die. The wire is drawn, immersed and washed in hot water at 65 ° C. for 2 seconds in the product diameter, further heated for 2 seconds with high-temperature steam at 110 ° C., dried, and then 0.8 g of synthetic oil per 10 kg of wire, MoS ₂ , WS ₂ , and ZnS were applied in an amount of 0.05 g per 10 kg of wire (0.15 g per 10 kg of wire in total of sulfides).

  FIG. 15 shows the relationship between the welding current and the feeding resistance in this case. The feeding resistance is hardly affected by the welding current, and there is no wire speed fluctuation in the entire practical current range.

An apparatus for measuring fusing force and feeding resistance is shown. It is a graph which shows the relationship between the welding current measured by this measuring apparatus, and feeding resistance. The relationship between the voltage drop E _C and the contact temperature T _max when the temperature T _{ERT of the} power supply chip is 300K, 400K, 500K, 600K, 700K, 800K, and 900K is shown. (A) is sectional drawing which shows the electric power feeding chip | tip, (b) is sectional drawing which shows the torch which attached this electric power feeding chip | tip. (A), (b) shows the result of plotting the relationship between the welding current value at each time and the voltage drop at the corresponding time, (a) is a comparative example that is out of the scope of the present invention, and (b) is the present. Examples which fall within the scope of the invention. (A), (b) shows the probability density distribution of the voltage drop amount in the 40A range of the currents 140A-180A of FIGS. 5 (a), (b). It is the graph which arranged the amount of diameter reduction (roll diameter reduction) using a roller die on the horizontal axis, and arranged the voltage drop amount at the time of welding on the vertical axis. It is a graph which shows the relationship between both taking the product of the temperature of washing water, and the washing | cleaning time on a horizontal axis, and making voltage drop amount into a vertical axis | shaft. It is a graph which shows the relationship between the induction heating temperature and the voltage drop amount at the time of welding. It is a graph which shows the relationship between a ZnS amount and a voltage drop amount by taking a ZnS amount on a horizontal axis and taking a voltage drop amount on a vertical axis. It is a graph which shows the relationship between the welding current of Example 1, and feeding resistance. It is a graph which shows the relationship between the welding current of Example 2, and feeding resistance. It is a graph which shows the relationship between the welding current of Example 3, and feeding resistance. It is a graph which shows the relationship between the welding current of Example 4, and feeding resistance. It is a graph which shows the relationship between the welding current of Example 5, and feeding resistance.

Explanation of symbols

1: Reel 2: Feeding roller 3: Conduit liner 5: Torch 6: Welded plate 8: Support device 11: Welding wire 12: Welding power source 20: Torch 21: Cable 22: Insulating cover 23: Connection portion 24: Power cable 25: Insulating cylinder 26: Sleeve 28: Anode 30: Feeding tip 31: Conductive body 32: Insulating sleeve 33: Tip of feeding tip

Claims (4)

Using a power supply tip having a power supply length of 2 to 4 mm at an average current of 150 to 170 A, setting the distance between the power supply tip and the base material to 20 to 24 mm, and setting the diameter of the free loop due to wire wrapping When carbon dioxide gas shield welding is performed at 700 to 800 mm, there is a probability that the voltage drop amount between the power supply tip and the welding wire at the time of welding exceeds 0.41 V in the current region where the instantaneous current value is 140 to 180 A. 70% or more, characterized in that 0.25 to 1.5 g of one or more oils and fats selected from the group consisting of vegetable oil, animal oil, mineral oil and synthetic oil are attached per 10 kg of wire. Wire for welding without copper plating. The copper plating-free welding wire according to claim 1, wherein the probability that the voltage drop exceeds 0.41 V is 80% or more. The copper plating-free welding wire according to claim 1, wherein a probability that the voltage drop amount exceeds 0.41 V is 90% or more. One or two or more selected from the group consisting of MoS ₂ , WS ₂ , and ZnS adhere to 0.01 to 0.25 g per 10 kg of wire on the surface of the wire or the surface layer having a depth of 100 μm from the wire surface. 5. The welding wire without copper plating according to claim 1, wherein the wire has no copper plating.

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