JPS6324119Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to an apparatus for annealing welding wire by heating it with electricity, and more specifically, it prevents sparks between the current-carrying electrode roller (hereinafter referred to as electrode roller) and the welding wire by preventing the running welding wire from deflecting. The present invention relates to an electrical annealing device for welding wire configured to avoid such occurrence. Drawn wire rods are often subjected to suitable heat treatment depending on their use, and one such heat treatment is annealing, which softens the wire rod, and is widely used in the field of welding wire. The mainstream method of annealing welding wire (hereinafter simply referred to as wire) is the so-called batch method, in which the wire is wound into a coil, placed in a heating furnace, heated for several to several dozen hours, and then cooled at an appropriate rate. However, the continuous current heating annealing method is attracting attention from the viewpoint of improving product homogeneity and productivity. In other words, in this method, the wire is brought into contact with an electrode roller while running in the axial direction, and is heated by electricity, and the temperature is rapidly raised to the required temperature by the Joule heat generated inside the wire, so the heating time is only a few seconds, and the production speed is reduced. The quality is extremely high. Figure 1 is a conceptual diagram showing a continuous current annealing line under consideration by the present inventors, and is an example of a case in which cold drawn wire is continuously annealed before being subjected to pickling and plating treatment. . The device is composed of a wire supply section A, an annealing section B, and a wire take-off section C. First, in the supply section A, the wire W (for example, wire diameter 2.8 mmφ) pulled out from the payoff bobbin 1 is transferred to the auxiliary take-off machine 6. It travels while being picked up and supplied to the annealing section B. The annealing part B has electrode rollers a ₁ ,
a ₂ , a ₃ (hereinafter representatively referred to as a); ceramic rollers b ₁ , b ₂ , b ₃ , b ₄ , b ₅ and line runout prevention roller 9, etc. are arranged as shown in the figure. While the wire W passes between them, the wire W is heated by electric power, annealed, and air-cooled. Note that b ₄ and b ₅ are air-cooled ceramic rollers in which several rollers are loosely fitted on the same axis, and since the wire storage length is several tens of meters, the annealing wire W is air-cooled while passing through these rollers. . Then, it reaches the wire pulling section C, and the main pulling machine 1
1. It sequentially passes through the vertical dancer rollers 12 and is supplied to the next process. By the way, the wire in the above-mentioned current heating annealing operation runs between each roller at high speed, and the wire runs between the electrode rollers a.
Since the current is applied from the point of contact with the contact point, the point of contact must be unstable, unlike in the case of a fixed contact. Therefore, the contact between the electrode roller a and the wire may be insufficient momentarily, and sparks may occur between the electrode roller a and the wire, causing spark scratches on the surface of the wire, or in extreme cases. There were times when the wire broke. Furthermore, the generation of sparks also caused spark scratches on the surface of the electrode roller a, resulting in an increased frequency of replacement of the electrode roller a. If the wire breaks, the entire annealing line will stop, causing a drop in productivity, and since the wire stops unevenly, the wire will become tangled or wrapped between the rollers.
The task of removing these has become extremely troublesome.
Furthermore, when restarting operation, the wires had to be routed correctly throughout the line, which required a great deal of effort. The present invention has been developed in view of these circumstances, and its purpose is to provide an electrical annealing device that can stabilize the contact between the electrode roller and the running wire and prevent the generation of sparks in the annealed part. It is something to do. The configuration of the present invention that achieves the above object is, in an electrical annealing apparatus for a wire, in which a plurality of rollers are arranged along the running line of the wire,
The gist is that the circumferential speed of at least the electrode roller among the rollers disposed in the annealing section is set so as to satisfy the following formula (1), and annealing is performed while applying tension to the running wire. It has the following. Vn ₊₁ = Vn {1+α(Tn ₊₁ −Tn)} + β …(1) [Vn ₊₁ : Circumferential speed of n+1st roller (m/min) Vn: Circumferential speed of nth roller (m/min) ) Tn ₊₁ : Wire temperature at the n+1st roller (°C) Tn: Wire temperature at the nth roller (°C) α: Coefficient of linear expansion of the wire β: Positive correction speed (m/min)] Hereinafter, the present invention will be described. I will explain the history of the research. First, the present inventors closely observed the state of spark generation. As a result, it was found that sparks occur frequently when the running wire between the rollers has a large deflection. That is, FIG. 2 is an explanatory diagram showing the spark generating means, and shows a state in which the wire W let out from the electrode roller a is causing a line runout phenomenon. In the figure, the contact point _E1 between electrode roller a and wire W becomes point E2 when wire W swings to position F, and _{point E3} when wire W swings to position G.
Move to each point. Normally, the cycle of line runout is very short, and when line runout occurs, the contact points mentioned above move as if jumping into each other. That is, one point on the wire W intermittently separates from or comes into contact with one point on the electrode roller a, and as a result, the electrode roller a and the wire W
A spark occurs between. After considering the above situation, the inventors of the present invention came up with the idea that it is absolutely necessary to suppress the swing of the running wire as much as possible in order to prevent the generation of sparks, and in order to realize this. As a result of intensive research, we succeeded in eliminating the deflection of the running wire and preventing the generation of sparks by adopting the above configuration. In other words, the runout of the running wire is an expression of slack in the wire between the rollers due to insufficient tension being applied to the running state of the wire, and this tension is constantly changing from a microscopic perspective. are doing. Therefore, slack in the wire repeatedly occurs and disappears periodically, and even when slack occurs, the degree of slack differs each time. In this way, insufficient tension in the wire causes wire deflection, which is the cause of spark generation, so it is a shortcut and important to eliminate tension defects in order to prevent sparks. be. However, the cause of tension failure is not fully understood, and it is thought that the cause is that the rotational speed of the electrode roller on the downstream side is relatively slow compared to the running speed of the wire. Ta. In other words, the wire runs without sufficient tensile strength. When we conducted research to find out the cause of insufficient tension, we found that the slack in the wire mainly occurred between electrode rollers a ₁ and a ₂ and between electrode rollers a ₂ and a ₃ . It was found that this phenomenon hardly occurs between the rollers, especially in the air-cooled roller section. However, the basic difference between the annealing section and the air cooling section is whether the temperature is being increased or decreased. That is, in the annealing section, the wire is heated between electrode rollers to raise its temperature, and then cooled and lowered in the air-cooled roller section. Therefore, the wire becomes longer as it undergoes thermal expansion as the temperature rises as it passes between the electrode rollers, and conversely contracts during the subsequent cooling process, but the wire length changes to the positive side due to this thermal expansion. Naturally, slack occurs in the wire and a wire runout phenomenon occurs. Under these circumstances, it was considered necessary to increase the circumferential speed of each roller in the annealing section to correspond to the longer wire length. The degree of this speed increase must be proportional to the degree of linear expansion of the wire, and this can be expressed as a general equation as shown in equation (2). Note that the right-hand side of equation (2) is sometimes referred to as V′. Vn ₊₁ = Vn {1+α(Tn ₊₁ −Tn)} …(2) [Vn ₊₁ : Circumferential speed of n+1st roller (m/min) Vn: Circumferential speed of nth roller (m/min) Tn ₊₁ : Wire temperature at the n+1st roller (°C) Tn: Wire temperature at the nth roller (°C) α: Linear expansion coefficient of the wire β: Positive correction several degrees (m/min)] Therefore, (2) When the circumferential speed of each roller was adjusted to match the formula (see Comparative Example 2 shown in Table 1 below), the slack in the wire between the rollers was almost eliminated and spark generation was reduced, but the final A slight spark occurred at the electrode roller. After further consideration of the cause, we came to the following conclusion. In other words, if the roller circumferential speed is set to V' to match equation (2), the wire running speed and roller circumferential speed will be the same, so the wire will not slack and sparks should be prevented. Yes, but
In this case, the roller in question is only capable of feeding the wire supplied from the upstream roller to the downstream roller (in other words, the roller is only capable of passing the wire supplied from the upstream roller to the downstream roller).
It merely rotates at a circumferential speed, but not at a circumferential speed that can positively apply tension to the wire between it and the upstream roller. The contact pressure between the roller and the wire at this time is extremely small, and if the tension fluctuates as described above, the wire easily separates from the roller and generates sparks. Therefore, it is necessary to increase the contact pressure between the roller and the wire, and for this purpose, it is necessary to generate tension in the wire between the roller and the upstream roller. In other words, in order to generate tension in the wire between the roller and its upstream roller, the circumferential speed of the roller must be such that the entire length of the wire fed from the upstream roller per unit time is sent to the downstream roller. In other words, the circumferential speed of the roller must be the same as the speed increase due to the linear expansion caused by the annealing heat, plus a positive correction speed. is required, and when expressed as a general formula, it becomes as shown in the above formula (1). Example 1
(See Table 1), the circumferential speeds of the rollers in the annealing section were adjusted to match equation (1), and no sparks were generated. This is because appropriate tension is applied to the wire between the rollers, eliminating wire runout, and at the contact point between the roller and the wire, the wire is fed while contacting the roller with an appropriate amount of contact pressure. . Note that the positive correction speed β mentioned above has an appropriate range depending on the wire diameter, material, surface quality, running speed, etc., and the lower limit is the smallest value that ensures the above effect, but zero Unless otherwise specified, a certain effect will be emitted, so there is no need to set it in a limited manner. On the other hand, if the correction speed becomes too large, the difference between the roller circumferential speed and the wire running speed becomes large, which increases the amount of wear on the contact surface between the roller and the wire, especially the current-carrying surface of the electrode roller, and increases the frequency of roller replacement. It is desirable to set this by considering the degree of wear of the roller. The present invention is roughly constructed as described above, and can almost eliminate the runout of the running wire between the rollers, as well as ensure the contact between the roller and the wire, especially the contact between the electrode roller and the wire. Thereby, the generation of sparks can be completely eliminated. Examples of the present invention will be described below. FIG. 3 is an explanatory diagram showing the main parts of the annealing part of the current annealing device, in which electrode rollers a ₁ , a ₂ , and a ₃ are connected to a motor (not shown) via a rotating shaft extending through the plane of the paper.
Each of the rollers actively rotates in the direction of the arrow, and the wire W runs between these rollers in the direction of arrow D. Note that the ceramic rollers b ₁ and b ₂ are freely rotating rollers. In the above device, the circumferential speeds of the electrode rollers a ₁ , a ₂ , and a ₃ were set as shown in Table 1, and the spark generation state was investigated, and the results shown in Table 1 were also obtained.

[Table] Comparative Example 1 is an example in which the circumferential speed of each electrode roller is the same with respect to the wire speed, and no spark was generated at electrode roller a ₁ , but sparks were generated at electrode rollers a ₂ and a ₃ . . Wire W connects electrode rollers a ₁ and a ₂
It was in a state of swinging between electrode rollers _a2 and _a3 . In Comparative Example 2, the peripheral speed of the downstream roller is higher than that of the upstream roller by the amount of elongation due to heating of the wire W, that is, the peripheral speed of electrode roller a ₁ is set to 40 m/min, while the peripheral speed of electrode roller a ₂ is set to 40 m/min. Speed 40.28m/min,
Electrode roller _A3 is set at 40.45 m/min.
Although no sparks were observed on electrode rollers a ₁ and a ₂ , sparks were generated on electrode rollers a ₃ . Furthermore, there was almost no deflection of the wire W. Comparative example 3 is an example in which the circumferential speed of a ₂ and a ₃ is lower than that of electrode roller a ₁ , and the spark is caused by electrode roller a ₁ ,
This occurs frequently in a ₃ . Embodiment 1 is an example in which the circumferential speed of electrode roller a ₁ is the same as the wire speed, and the circumferential speed of electrode rollers a ₂ and a ₃ is faster than the wire speed by more than the elongation due to heating.
No sparks were generated at all a ₁ , a ₂ , and a ₃ . Also, no wobbling of the wire between the rollers was observed. In Example 2, the circumferential speeds of the electrode rollers a ₂ and a ₃ were increased as in Example 1, but the amount of speed increase was much greater, and no sparks were observed at all. However, the wear of the electrode rollers was large and the frequency of replacement increased.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the outline of the wire annealing device, Fig. 2 is an explanatory diagram showing the spark generation situation,
FIG. 3 is an explanatory view of the main part of the annealing part according to the current annealing apparatus of the present invention. a ₁ , a ₂ , a ₃ ... electrode roller, b ₁ to b ₅ ... ceramic roller, B ... annealing section, W ... wire.

Claims (1)

[Scope of Claim for Utility Model Registration] In a welding wire current annealing device in which a plurality of rollers are arranged along the traveling line of the welding wire, at least one of the current-carrying electrode rollers among the rollers disposed in the annealing section is provided. An electrical annealing device for a welding wire, characterized in that the circumferential speed is set to satisfy the following formula (1), and the running wire is annealed while applying tension. Vn ₊₁ = Vn {1 + α (Tn ₊₁ − Tn)} + β …(1) [Vn ₊₁ : n ₊ 1st roller circumferential speed (m/min) Vn: nth roller circumferential speed (m /min) Tn ₊₁ : Wire temperature at the n ₊ 1st roller Tn: Wire temperature at the nth roller α: Coefficient of linear expansion of the wire β: Positive correction speed (m/min)]